Increasingly, the management of large precast concrete plants and house-building plants is used in the production of a line for non-formwork molding of precast concrete products. This technology was known back in the 70s in the USSR, but in connection with the decisions of "state criminals" in the 90s, the industry of its application was destroyed to the ground. Now the tasks of officials have not changed much, so only foreign BOF equipment is presented on the market. These are: extruders (Elematic), splitformers (Weiler, Echo), vibropresses (Tensyland, Technospan).

BOF lines make it possible to manufacture: hollow core slabs, piles, beams, road slabs, fence structures, wall and interior partitions, trays, lintels and other reinforced concrete products in large quantities, of high quality. However, not always production with the use of BOF can be economically justified, and not always imported equipment means the best. At its core, all this equipment works according to the same principle: “I loaded concrete - I got reinforced concrete products at the output”, however, extruders, splitformers and vibropresses have a different design and related features.

The extruder feeds the concrete onto the forming element of the machine with the help of an auger. Given the constant contact of the working mechanisms of the machine with a hard mixture, they wear out quickly, but the finished products are of very high quality.

The design of the splitformer provides for the installation of vibrators on the forming equipment of the machine. Replacing tooling or other maintenance on a splitformer is time consuming.

The vibropress mechanism is much simpler and consists in compacting the mixture in front of the shaping tool. However, this type of BOF machines makes very high demands on concrete, and any violation of the concrete mix preparation technology leads to production defects and equipment failure.

Lack of "fool-proof". BOF lines presented in Russia are fully imported equipment made in Spain, Finland and other countries. Imported equipment does not have guaranteed protection against various industrial accidents that often occur in Russia. The equipment of all types of lines (regardless of the features) requires the use of high quality concrete and does not allow filler fractions larger than a given size to enter the mechanisms. Any "accidental" bolt, nut or large stone can put the molding machine out of action. In real Russian conditions, it can be very problematic to ensure the high quality of the concrete mix entering the plant. The quality of the mixture is not the only requirement. Cleaning the machine from concrete residues upon completion of molding and other mandatory procedures require additional equipment and special observance of the production work schedule. It was precisely because of the lack of highly qualified specialists in the workshops of reinforced concrete factories in the 70s of the last century that the BOF technology did not find its application.

The cost of lines for formworkless molding of reinforced concrete products

The cost, as well as the productivity of the BOF lines, is several times higher compared to the implementation of the technology using classic metal molds in the production of reinforced concrete products. Investments in such production can be expedient only if there is a constant high demand for reinforced concrete products (not just high, but very high demand - taking into account the huge productivity of these lines).

The average cost of a turnkey set of BOF equipment is about 60 million rubles! The high cost also distinguishes ordinary spare parts for BOF lines, which in fact is exacerbated by the long delivery times for the necessary spare parts.

Difficulties in modernizing lines. The production of various types of concrete products on the BOF lines became possible thanks to removable shaping equipment, however, it is simply impossible to convert such a line to another type of production without capital investments. It is also necessary to keep in mind the complexity of the operation of changing the tooling on a splitformer and, again, take into account the average cost of tooling for one product - about 1 million rubles.

The problem of coordination of working drawings. Despite the high declared number of products that, from a technical point of view, can be manufactured on the BOF lines, the number of albums of agreed working drawings is much less. And it is simply impossible to use inconsistent products in multi-storey construction.

In practice, the introduction of such "capricious" formworkless molding lines is justified only if a guaranteed wide sales of products (for several years ahead) and compliance with the highest requirements for the organization of production.

Moscow 1981

Published according to the decision of the section of the factory technology of concrete and reinforced concrete of the NTS NIIZhB Gosstroy of the USSR dated March 6, 1981.

The technology for the production of prestressed reinforced concrete structures by the formless method at all stages (preparation of concrete mix, preparation of steel stands, laying and tensioning of reinforcement, molding, heat treatment, cutting a strip of hardened concrete into products and their transportation) is described. The requirements for the quality of finished products are given.

FOREWORD

In recent years, the USSR has been developing the formless production of reinforced concrete structures on linear stands, on which products of a constant section along the length of the stand can be manufactured by continuous molding: multi-hollow floor panels, flat and trough-shaped slabs, single-layer and three-layer wall panels, etc.

These Recommendations are intended for practical use at prefabricated reinforced concrete plants, where formless production of reinforced concrete structures will be introduced on linear stands equipped with self-propelled forming units and other equipment purchased from Max Roth (Germany) or reproduced in the USSR under the license of this company, and also describe the order of the technological process.

The formless production method using self-propelled forming units provides for special requirements for the quality of concrete mixtures, their transportation to the forming units, the control of a continuously moving forming unit, the laying and tensioning of reinforcement, heat treatment, stripping and transportation of products.

The recommendations were drawn up on the basis of a practical verification of the provisions of the technical documentation of the Max Roth equipment under production conditions at the Seversky Concrete Concrete Plant of Glavsreduralstroy of the USSR Ministry of Tyazhstroy.

The recommendations were developed by the NIIZhB Gosstroy of the USSR (candidates of technical sciences S.P. Radashevich, E.Z. Akselrod, M.V. Mladova, V.N. Yarmakovskiy, N.N. Kupriyanov) with the participation of Glavsreduralstroy of the Ministry of Heavy Construction of the USSR (engineers E.P. Varnavsky, S.N. Poish, V.N. Khlybov) and UralpromstroyNII project of Gosstroy of the USSR (candidates of technical sciences A.Ya. Epp, R.V. Sakaev, T.V. Kuzina, I.V. Filippova, Yu. N. Carnet, engineer V.V. Anishchenko).

Directorate of NIIZhB

GENERAL PROVISIONS

1.1. These Recommendations apply to the manufacture of prestressed concrete products up to 1.5 m wide and up to 30 cm high (hollow-core floor panels and wall panels) from heavy and lightweight concrete using the formless method.

1.3. Features of formless production under the license of Max Rot are:

multi-stage continuous molding of products from rigid concrete mixtures;

implementation of vibration impact on the concrete mixture by working bodies by contact only with the mixture (surface layer-by-layer compaction);

continuous movement of the compacting elements of the machine relative to the laid concrete mixture.

The technological line for the formless production of prestressed concrete products must have the following set of equipment:

steel stands size 150´ 4 m with oil heating registers under them (technological lines with equipment reproducible in the USSR can have smaller stands);

hydraulic tensioning devices for group tensioning of reinforcement and compensation of tension losses during heating of the stand and reinforcement during heat treatment (group hydraulic jacks);

hydraulic jack type "Paul" for a single tension of reinforcement (single hydraulic jack);

self-propelled rebar spreader with deflecting and cutting devices;

coil holders for wire or strand reinforcement;

self-propelled forming unit with dosing bins;

trolleys with a heat-insulating blanket to cover the freshly molded concrete strip for the duration of the heat treatment;

vibroknife for cutting raw concrete mass;

saws with a diamond blade for cutting hardened concrete;

self-propelled hoisting and transport machine with pneumatic suction cups for removal from the stand and transportation of finished products;

stand cleaning machine;

installation for heating oil (coolant) type MT-3000 (Heinz company) or HE-2500 (Karcher company).

In addition, the production line must have a special post for washing the molding unit.

1.4. The peculiarity of the molding is that the forming unit, made in the form of a portal, on which distributing hoppers, three stages of compacting vibroelements, movable void formers, shaping and separating moving elements, a lubrication and plasticization system of the stand and controls, is mounted, moves smoothly with the help of adjustable rope-tensioning hydraulic device. At the same time, the forming unit, by means of an automatic device, lays and presses the transverse upper rod reinforcement and smoothes the open surface of the product.

1.5. The forming unit allows, by appropriate readjustment, to produce products of various widths and thicknesses. At the same time, the total width of the molded products does not exceed 3.6 m, the height is not more than 30 cm.

1.6. For the manufacture of products, concrete mixtures with a hardness of 20 - 40 s (GOST 10181 -81) can be used.

2. TECHNOLOGY FOR MANUFACTURING REINFORCED CONCRETE STRUCTURES BY THE NO-SHELL METHOD

concrete mix requirements

2.1. Hollow-core panels and solid slabs are formed from a concrete mixture on a dense aggregate with a design concrete grade for compressive strength of 300 - 500.

2.2. For forming multi-hollow panels and solid slabs, concrete mixtures with a hardness of (25 ± 5) s according to GOST 10181-81 can be used at a molding speed of (1.0± 0.2) m/min.

2.3. For the preparation of concrete, cement with a normal cement paste density (NCCT) of no more than 27% should be used. The use of cements with a higher HCFC can lead to a violation of the ratio between sand and cement and, consequently, to poor mix formability.

2.4. Sand must comply with the requirements of GOST 10268-70. The presence of grains larger than 10 mm in the sand is not allowed.

The strength of the aggregate must be at least 2 times greater than the strength of concrete.

2.6. In order to meet the requirements for the rigidity of the concrete mixture and the strength of concrete, it is necessary to determine the following characteristics of raw materials for calculating and correcting the composition of the concrete mixture:

for cement

activity R c , MPa - in each batch;

NGNT, % - 1 time per shift;

density ρ, g/cm 3 - for each type of cement;

for sand

bulk density g , kg / m 3 - 1 time per shift;

standard (standard deviation) of grains larger than 5 mm per shift, % - in each batch;

particle size module M kr - 1 time per shift;

contamination (elutriation), % - 1 time per shift;

natural humidity, % - 1 time per shift;

for crushed stone

density ρ, g/cm 3 - for each open pit;

bulk density g , kg / m 3 - 1 time per shift;

standard of grains larger than 5 mm per shift, % - in each batch;

contamination, % - 1 time per shift;

strength (crushability), MPa - in each batch;

natural humidity, % - 1 time per shift.

According to the characteristics obtained, the factory laboratory calculates the composition of the concrete mixture, guided by the provisions set forth in paragraphs. - these Recommendations.

Shch = Shch p - 0.01shch p (to + f), (2)

where to and f- standards of grains larger than 5 mm per shift, respectively, in crushed stone and sand, %;

Shch r - estimated amount of crushed stone, kg.

In this case, the consumption of mixed sand P cm and mixed crushed stone W cm is determined by the formulas

(3)

where with and d- accordingly, the amount of sand in crushed stone and crushed stone in sand,%;

W cm \u003d W + P - P cm. (4)

2.10. Correction of consumption of materials depending on the moisture content of aggregates W, the presence of sand in crushed stone and crushed stone in sand, cement activity R c , NGCT, voids of crushed stone a carried out if the value newly obtained during the test differs from the previously used one as follows:

W - by ± 0.2%; R - by ± 2.5 MPa; NGCT - by ± 0.5%;

a - by ± 1.0; M cr - by ± 0.1.

2.11. The strength of concrete is determined by the results of testing cubes molded from a control sample of concrete with a weight, the specific pressure of which is 4 · 10 -3 MPa. The bulk density of freshly molded samples should be equal to the theoretical (calculated) bulk density with a tolerance± 2%. Control cubes are steamed together with the product on the stand.

Testing of samples to determine the strength is carried out in a hot state (3 samples per stand).

2.12. The molding of wall panels and blocks is carried out from concrete mixtures on a porous aggregate, while using concrete: structural - grades M150 - M200, structural and heat-insulating - grades M50 - M100 and heat-insulating - grades M15 - M25.

2.13. In the manufacture of structural and heat-insulating lightweight concrete grades M50 - M100, a mixture of expanded clay gravel fraction 5 - 10 mm grade for bulk density not higher than 500 and fraction 10 - 20 mm grade for bulk density not higher than 400, expanded clay sand grade for bulk density not higher 800, meeting the requirements of GOST 9759-76.

For the manufacture of a heat-insulating layer of large-porous concrete M15 - M25, it is recommended to use expanded clay gravel fraction 10 - 20 grade for a bulk density of not more than 350.

In the manufacture of structural expanded clay concrete grades M150 - M200, it is necessary to use expanded clay gravel with a fraction of 5 - 10 mm of a grade of strength not lower than H125.

2.14. The workability of the concrete mixture for structural expanded clay concrete should be characterized by rigidity in the range of 20 - 40 s according to GOST 10181 -81.

2.15. The working dosage of materials for batching is issued by the factory laboratory at least once per shift with a mandatory check of the stiffness of the concrete mix of the first batches.

2.16. Dosing of cement, water and aggregates should be carried out in accordance with GOST 7473-76.

Dosing of expanded clay gravel and porous sand should be carried out by volume-weight method with adjustment of the composition of the mixture based on the control of the bulk density of large porous aggregate and sand in the weight dispenser.

2.17. The preparation of concrete mixture for heavy structural and structural-heat-insulating lightweight concrete is recommended to be carried out in forced-action mixers.

The preparation of the concrete mixture for the heat-insulating layer of coarse-porous concrete should be carried out in concrete mixers with gravity action.

2.18. The duration of mixing of a concrete mixture of a given hardness is set by the factory laboratory in accordance with GOST 7473-76 and is observed with accuracy± 0.5 min.

2.19. Control of the mixing mode is carried out at least twice a shift.

2.20. The rigidity of the concrete mixture coming from each concrete mixer is checked at least three times during the formation of one stand.

Stand preparation

2.21. After removing the finished products, the stand is cleaned by moving a cleaning machine along it, which is installed on the stand with a crane.

2.22. The cleaning machine can operate in two modes:

"normal cleaning" - when cleaning the stand without dried concrete;

"Full brush mode" - if there are residues of dried concrete on the stand.

2.23. To clean a large amount of raw concrete residues, a special scraper in the form of a bucket with side walls is hung on the cleaning machine. To clean hardened concrete, which has a strong adhesion to the stand, a scraper beam suspended from the machine is used. The speed of the machine is selected in such a way that the stand is cleaned in one pass of the machine.

2.24. A stand with a small amount of small residues of concrete crumbs is cleaned with a jet of water supplied from a hose under pressure.

Laying and tensioning reinforcement

2.25. Reinforcement is laid after cleaning the stand. The wire (strands) are drawn using a self-propelled rebar spreader consisting of three or six coil holders located behind the stands from the side of group hydraulic jacks.

The self-propelled rebar spreader must move along the stand at a speed of 30 m/min.

Fixation of the reinforcement in the stops at the ends of the stand is carried out manually.

2.26. A batch of wires (strands) fixed on the bench is tightened with a single hydraulic jack at the passive end of the bench until the assembly tension of the reinforcement is equal to 90% of the specified force.

The operation is repeated until the installation tension of all reinforcing elements is set.

2.27. After tensioning the reinforcement, protective brackets must be installed on the stand in case of breakage of the reinforcing elements during its final tension.

2.28. The tension of the entire reinforcement package to 100% of the specified force is performed by a group hydraulic jack at the active end of the stand after the self-propelled forming unit is installed on it and prepared for operation.

The entire process must be carried out in accordance with Max Roth's instructions.

Molding

2.29. The forming unit is installed by a crane on the passive end of the stand; receiving hoppers are installed on the unit, and the power cable and the cable of the rope-tensioning system are delivered to the active end of the stand using a rebar spreader trolley and attached, respectively, to the electrical connector and the bracket of a special stop located behind the group hydraulic jacks.

2.30. Adjustment and adjustment of the forming unit is carried out on the basis of the instructions for servicing the forming unit included in the set of technical documentation for the equipment supplied by the manufacturer, as well as in accordance with these Recommendations.

2.31. The void formers must be installed in such a way that the distance from the stand surface to the lower edge of the rear part of the void formers corresponds to the design in the product, and in the front part it is 2 mm higher. The rear part of the boards and dividing partitions must be installed 1 mm higher than the stand, and the front part - 2 mm.

2.32. Vibrocompactors of the 1st stage are installed in accordance with the thickness of the base of the manufactured panels. The front of the bars supported by the rubber buffers must be set 5 mm higher than the rear. In this case, the rear part of the vibrocompactors of the 1st stage should be lowered by 5 mm from the bottom surface of the void formers following them.

2.33. Vibratory compactors of the 2nd stage are installed in such a way that their rear part is at a distance of 5 mm above the void formers.

The angle of inclination of the vibrocompactors is chosen depending on the thickness of the panel and the consistency of the concrete mixture.

2.34. The mechanical ramming device for sinking transverse reinforcement must be installed in the lower position 10 mm above the top mark of the molded product. In this case, the back part of the 3rd stage vibrocompactors or the surface of the steel sheet of the stands serves as a control mark.

2.35. The plates on which the 3rd stage vibratory compactors are attached must be installed horizontally and rest on rubber shock absorbers. In this case, the working sealing plate in contact with the concrete mixture will take the design inclined position.

2.36. A block of bunkers with a total capacity of 10 m 3 with an automatic device for loading the concrete mixture and supplying the mixture to the hoppers is installed using an overhead crane on the portal of the molding machine and fixed with bolts.

2.37. Before the start of molding, the operation of all three stages of vibrocompaction, void formers, sides and dividing partitions, and the automatic concrete supply mechanism should be checked at idle.

2.38. The rotation of the vibrators of all three stages of compaction must be carried out towards the movement of the molding machine. If the direction of rotation does not match, the phases must be changed.

2.39. When adjusting the position of the sides and dividing partitions that form the side edges of the products, it is necessary to exclude the possibility of contact between the sides and the stand during the molding process. The installation of the sides and dividing partitions is carried out at the highest point of all the stands, to determine which the forming unit sequentially moves along all the stands after their installation before trial molding.

2.40. The gap between the 2nd stage vibratory compactors and the tensioned top reinforcement should be (20± 5) mm.

2.41. Before the start of molding, the unit is set in its original position at the beginning of the passive end of the stand; the hoppers of the automatic loading mechanism are filled with concrete mixture supplied from the bucket with the help of an overhead crane.

2.42. Before molding, a device is installed to maintain and fix the stressed reinforcement. Its installation is carried out in such a position of the forming unit, when the distance between the distribution hopper of the 1st stage of compaction and the reinforcement spacers is 100 - 150 mm. The direction of the wires (strands) must coincide with the direction of the stand axis; if necessary, adjust the position of the guide bars.

2.43. During the molding process, the concrete mixture must be fed into the feed hoppers of all three stages of compaction in an amount equal to 1/3 of the volume of the hopper, which provides a constant backwater necessary for uniform supply of the mixture under the compacting organs of the machine. In the absence of mixture back-up in feed bins, the mixture is supplied under the compacting bodies in insufficient quantities, which leads to undercompacting of concrete in the products.

2.44. Dosing of the mixture from feed bins is carried out by gates placed on the rear wall of the bins using slider levers.

The reciprocating movement of the 2nd and 3rd stage dosing hoppers should be adjusted to 20 - 30 counts / min. At the same time, it is necessary to supply such an amount of concrete mixture to the 3rd stage of compaction that would form a small roller in front of the vibrocompactors. This requirement is met by dosing the mixture from the 3rd stage hopper, as well as by changing the height of the mechanical compactor.

2.45. Forming of products should be carried out continuously throughout the entire stand without stopping the forming unit. The molding speed, depending on the stiffness of the mixture and the height of the molded product, must be selected experimentally and can be taken equal to 0.5 - 2.0 m/min.

When forming multi-hollow panels from concrete mixtures with a stiffness (25± 5) with recommended speed (1.0± 0.2) m/min. When forming three-layer wall panels with a thickness of 250 - 300 mm from concrete mixtures with a hardness of 20 - 40 s, a speed of 1.0 - 1.5 m / min is recommended.

The total duration of the molding of a stand strip 150 m long should not exceed 3 hours, and the strength of cube samples molded at the beginning of concreting before heat treatment should not exceed 0.5 MPa.

2.46. When forming multilayer panels of expanded clay concrete, the back part of the vibrocompactors of the 1st stage is installed according to the drawing of the product above the surface of the stand at a distance equal to the thickness of the lower structural layer of the product; the hopper gate should be installed 100 - 120 mm above the lower structural layer.

2.47. The rear part of the vibrocompactors of the 2nd stage is set 10 mm above the specified heat-insulating layer, and the gate of the dosing hopper - 50-60 mm.

In this case, the vibrators of the 2nd stage of compaction must be switched off.

2.48. The rear part of the vibrocompactors of the 3rd stage is installed above the surface of the stand at a distance equal to the thickness of the product, and the gate of the dosing hopper is 100-120 mm above the surface of the product.

2.49. The treatment of the stand with OE-2 lubricant and the plasticization of the lower layer of the concrete mixture with water is carried out using special devices installed in the front part of the forming unit.

2.50. Before the end of molding, 2 m before the edge of the stand, it is necessary to remove the bars of the reinforcement guides. The concrete mixture must be fed into the hoppers of the loading device and supply hoppers evenly in such a way that by the end of the molding it will be completely used up.

2.51. After the molding is completed, the unit moves close to the turntable of the tension rope, its movement stops and all functional units of the unit are turned off.

2.52. At the end of molding at each stand, the molding unit is washed with a high-pressure water jet at a specially equipped washing post.

After the working shift, a general washing of the forming unit is carried out. Prior to this, it is advisable to dismantle the 2nd and 3rd stages of sealing. Mechanical impact (tapping) is prohibited. All mechanisms and motors must be covered before washing.

Molding defects and their elimination

2.53. Wire break (strands). Check to see if any of the three sealing steps are in contact with the wire. Otherwise, the wire may trap and break in the compacted concrete.

2.54. Violation of the adhesion of the strand to concrete or deviation from the design position. It is necessary to check whether the wire (strands) and vibrocompactors of the 2nd stage are in contact and whether the aggregate fraction of more than 10 mm does not get into the concrete mixture.

2.55. Roughness of the upper surface of the panels and transverse cracks. It is recommended to check that the consistency of the concrete mixture is the required one, as well as the conformity of the required molding and dosing speeds of the concrete mixture for the 3rd stage of compaction.

2.56. Cracks on the bottom surface of the panels. It is necessary to check the angle of inclination when installing the 1st stage vibratory compactors. In the case of a large angle of inclination, the horizontal component increases during the movement of the working body and can lead to discontinuities (exceeds the adhesive force of the concrete mixture with the stand).

The position of the 1st stage vibratory compactors in relation to the void formers should be checked. If they are installed incorrectly, the void formers will destroy the already compacted base of the panels.

2.57. Formation of cracks on the side faces of panels. It is recommended to check the speed of movement of the boards and separating elements and, if necessary, correct it.

It should be checked whether the sides and separating elements are in contact with the stand.

2.58. Insufficient wall compaction between voids. The dosage of the concrete mixture in the 2nd stage of compaction should be checked. It is recommended to check the angle of inclination of the 2nd stage vibratory compactors and their operation.

2.59. When checking the operation of vibratory compactors, it is necessary to make sure that all vibrators are in good condition.

The vibration amplitude of the seals should be:

for the 1st stage - 0.9 - 1.0 mm;

for the 2nd stage - 0.7 - 0.8 mm;

for the 3rd stage - 0.3 - 0.35 mm.

heat treatment

2.60. During the molding period, the oil heated in the oil heating unit up to 100 °C and circulating in the bench registers ensures the temperature of the steel sheets of the bench at least 20 °C.

2.61. Upon completion of molding and coating of freshly molded concrete with a heat-insulating blanket, the oil temperature is raised to 170–200 °C for 7 hours, which ensures the stand temperature is about 90 °C, and the concrete warms up to 65–70 °C.

The control of the concrete temperature during the heat treatment period is carried out according to the graphs of the relationship between the oil temperature in the system and the concrete temperature based on the oil temperature readings on the control panel of the oil heating plant.

2.62. Isothermal heating is carried out for 7 hours, while the oil temperature gradually decreases to 100 °C.

2.63. Cooling of products before the transfer of stress to concrete is not allowed [see. "Guidelines for the heat treatment of concrete and reinforced concrete products" (M., 1974)]. The transfer of compression forces to concrete is recommended to be carried out no later than 0.5 hours after the end of the isotherm and testing of control samples. In this case, the temperature of the concrete should be reduced by no more than 15 - 20 ° C relative to the temperature of the concrete during isothermal heating.

2.64. During heat treatment, the stand and fittings are tightened when they are extended by an automatic device mounted on group hydraulic jacks, due to the operation of a limit switch and an automat for maintaining the tension of the fittings. The operation time of the machine is recommended to be set using a time relay for 3 minutes.

Cutting products and their transportation

2.65. The tension is released by a group hydraulic jack at the active end of the stand, followed by trimming of the reinforcement at the passive end of the stand.

2.66. Cutting a concrete strip into products of a given length is carried out with a saw with a diamond blade, starting from the passive end of the stand. Use of abrasive disks is possible. The time of one transverse cut of a concrete mass with a width of 3.6 m is 5 minutes.

2.67. The removal of products from the stand and their storage at the free end of the stand or its continuation is carried out by a self-propelled lifting and transport machine with pneumatic suction cups.

2.68. Further transportation of products to an export trolley or car is carried out by an overhead crane using a special traverse of a no-lift lift.

Quality control of finished products

2.69. Quality control of finished products is carried out by the plant's technical control department on the basis of current regulatory documents (TU, working drawings) and these Recommendations.

2.70. The deviation of the dimensions of multi-hollow panels should not exceed:

in length and width -± 5 mm;

in thickness - ± 3 mm.

2.71. The thickness of the protective layer of concrete to the working reinforcement must be at least 20 mm.

2.72. Panels must have straight edges. In individual panels, the curvature of the lower or side surface is allowed no more than 3 mm over a length of 2 m and no more than 8 mm along the entire length of the panel.

2.73. There should be no sinks on the lower (ceiling) surface of the panels. On the upper and side surfaces of the panels, separate small shells with a diameter of not more than 10 mm and a depth of up to 5 mm are allowed.

2.74. Collapses are not allowed in the panels, as well as filling of hollow channels with concrete.

2.75. Panels are produced without reinforced ends.

2.76. The appearance of the panels must meet the following requirements:

the lower (ceiling) surface must be smooth, prepared for painting without additional finishing;

on the lower (ceiling) surface of the panels, local sagging, grease and rust spots and open air pores with a diameter and depth of more than 2 mm are not allowed;

sagging and sagging along the longitudinal lower edges of the panels are not allowed;

it is not allowed to cut concrete along the horizontal edges of the ends of the panels with a depth of more than 10 mm and a length of 50 mm per 1 m of the panel;

cracks are not allowed, except for shrinkage surface cracks with a width of not more than 0.1 mm;

slippage of stressed reinforcement is unacceptable.

2.77. Deviations from the design dimensions of wall panels should not exceed:

by lenght

for panels up to 9 m long - +5, -10 mm;

for panels longer than 9 m - ± 10 mm;

height and thickness - ± 5 mm.

2.78. The difference between the diagonals of the panels should not exceed:

for panels up to 9 m long - 10 mm;

for panels longer than 9 m - 12 mm.

2.79. Non-flatness of panels, which is characterized by the largest deviation of one of the corners of the panel from a plane passing through three corners, should not exceed:

for panels longer than 9 m - 10 mm.

2.80. Panels must have straight edges. Deviation from a straight line of the real surface profile and panel ribs should not exceed 3 mm over a length of 2 m.

Over the entire length of the panel, the deviation must not exceed:

for panels up to 9 m long - 6 mm;

for panels longer than 9 and - 10 mm.

2.81. Sinks, air pores, local bulges and depressions on the surface of the panel intended for painting should not exceed:

in diameter - 3 mm;

in depth - 2 mm.

2.82. Grease and rust spots on the surface of the products are not allowed.

2.83. It is not allowed to break concrete ribs with a depth of more than 5 mm on the front surfaces and 8 mm - on non-front surfaces, with a total length of more than 50 mm per 1 m of the panel.

2.84. Cracks in the panels are not allowed, with the exception of local single surface shrinkage cracks with a width of not more than 0.2 mm.

2.85. The moisture content of concrete in panels (in % by weight) should not exceed 15% for concrete on porous gravel and 20% for concrete on porous crushed stone.

The moisture content of the concrete in the panels is checked by the manufacturer at least once a month.

Wall panel finishing

2.86. Obtaining the texture of wall panels is carried out using special equipment. Applying a cement-sand finishing mortar to the surface of the concrete strip and obtaining a smooth front surface of the products is carried out using a finishing unit attached to the forming unit and consisting of a mortar hopper and smoothing bars.

2.87. When decorative relief finishing of products with cement-sand mortars, one should be guided by the "Instructions for finishing the facade surfaces of panels for external walls" (VSN 66-89-76).

3. SAFETY

3.1. At the plant, where the production of prefabricated reinforced concrete structures by the formless method on linear stands is organized, all work is carried out in accordance with the "Rules for safety and industrial sanitation at factories and factory polygons of reinforced concrete products" (M., 1979), as well as chapter SNiP III-16-80 Concrete and reinforced concrete prefabricated structures.

3.2. Special safety rules for carrying out certain technological operations (heating oil, laying and tensioning fittings on the bench, cutting finished products, etc.) are set out in special instructions for carrying out these works contained in the technical documentation for the equipment and supplied with the equipment by the plant -manufacturer.

3.3. Special safety regulations should be duplicated on posters in the shop.

3.4. Personnel arriving at the plant must undergo a special training course on the technology of working at the stand, pass the test and undergo quarterly briefings.

3.5. When working on an oil heating installation, it is necessary to take into account the “Recommendations for reducing the fire hazard of installations using flavored heat transfer oil AMT-300” (M., 1967).

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MODERN TECHNOLOGICAL LINES FOR THE PRODUCTION OF FLOOR SLABS

MODERN PROCESS LINES FOR THE FLOOR SLABS PRODUCTION

E.C. Romanova, P.D. Kapyrin

E.S. Romanova, P.D. Kapyrin

GOU VPO MGSU

The article discusses modern technological lines for the production of floor slabs by the formless molding method. The technological process, the composition of the line are disassembled, the characteristics of the equipment used are indicated.

In current article the modern process lines for off-formwork slabs production is investigating. The whole technological process is examined as well as lines composition. The characteristics and qualities of the used equipment are mentioned.

At present, the key to the success of the enterprise for the production of concrete products is the production of a wide range of products. Consequently, a modern enterprise, plant, combine needs automated production lines, easily adjustable equipment, universal machines, and the use of energy-saving and energy-efficient technologies.

Technologies for the production of reinforced concrete products and structures can be divided into traditional (conveyor, aggregate-flow, cassette) and modern, among which a special place is occupied by continuous formless molding.

Formless molding, as a technology, was developed during the Soviet Union and was called "combine-plating technology". Today, the technology is in demand in Russia; with each operating experience, it is improved by our specialists, while using the experience of foreign companies.

The technological process of the formless molding method is as follows: products are molded on a heated metal floor (about 60 ° C), reinforced with prestressed high-strength wire or strands, the molding machine moves along the rails, leaving behind a continuous band of molded reinforced concrete.

Three methods of continuous formless molding are known: vibrocompression, extrusion and tamping.

Packing method

The essence of the tamping method is as follows: the forming machine moves along rails, while the compaction of the concrete mixture in the forming plant is carried out by special hammers. On fig. 1 shows a diagram of a molding machine for continuous ramming.

Rice. 1 Scheme of the forming plant for continuous molding by tamping

The lower layer of the concrete mixture is placed on the molding paths from the hopper 1 and compacted with a high-frequency vibration compactor 3. The upper layer of the concrete mixture is fed from the hopper 2, and is also compacted with a high-frequency compactor 6. Additionally, the surface of the slab is compacted with a shock-vibration rammer. Stabilizing plates 4 are installed after both surface compactors to improve the compaction of the concrete mix. The method is not widely used, since the installation is extremely difficult both to operate and maintain.

extrusion method

The technological process consists of several successive stages:

1. Previously, a special track cleaning machine cleans the metal coating, and then lubricates the tracks with oil.

2. Reinforcing ropes are stretched, which are used for reinforcement, tension is created.

3. Then the movement of the extruder 1 begins (Fig. 2), which leaves behind a strip of molded reinforced concrete 2 (Fig. 2).

Rice. 2 extruder

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The concrete mixture in the screw-stone extruder is injected through the holes of the forming equipment in the direction opposite to the movement of the machine. Forming proceeds horizontally, and the forming machine, as it were, is repelled from the finished product. This ensures uniform compaction along the height, making extrusion indispensable for molding large-sized products with a height of more than 500 mm.

4. Then the product undergoes heat treatment - it is covered with heat-insulating material, and the stand itself is heated from below.

5. After the concrete has gained the required strength, the slab is cut to the design length with a diamond saw with a laser sight, having previously relieved the stress.

6. After sawing, the hollow core slabs are removed from the production line using lifting clamps.

The technology makes it possible to produce slabs 5-10% lighter than traditional ones. The high compaction of the concrete mixture provided by the screws makes it possible to save about 20 kg of cement per cubic meter of the mixture.

In addition to the advantages, the technology has significant disadvantages:

The operating costs are high. Rigid concrete mix is ​​abrasive causing auger wear

Extrusion equipment is designed for cement and inert materials only of the highest quality (usually grade M500)

Limited range of products. Extrusion is not intended for the formation of beams, columns, crossbars, poles and other products of small section.

vibrocompression method

The vibrocompression method is optimal for the manufacture of any products with a height of not more than 500 mm. The forming machine is equipped with vibrators to compact the concrete mixture. It is reliable and durable, does not contain wearing parts. The range of manufactured products is diverse, with equal success produced hollow core slabs, ribbed slabs, beams, crossbars, poles, lowering piles, lintels, etc. An important advantage of the forming machine is its unpretentiousness to the quality of raw materials and the associated efficiency. High quality products are achieved using cement grade 400, sand and gravel of medium quality.

Let us consider a modern complex for the formless production of hollow core slabs (Fig. 3) and describe in detail the technological process.

The production cycle of formless molding includes the following operations: cleaning and lubricating the molding track, laying out the reinforcement, tensioning the reinforcement, preparing the concrete mixture, molding products, heat treatment, relieving stress from reinforcement, cutting products into segments of a given length, and export of finished products.

The complex includes:

Industrial decks

Slipformer

concrete aspirator

Multifunctional trolley

Automatic plotter (marker)

Universal Sawing Machine

Saw for fresh concrete

Rice. 3 Technological line for the production of prestressed hollow core slabs

Technical characteristics and advantages of manufactured products:

1. High strength characteristics.

2. High dimensional accuracy.

4. Possibility of manufacturing various standard sizes in length with any step.

5. The possibility of manufacturing oblique ends of products (it is possible to cut at any angle).

6. Possibility of forming openings in ceilings for the passage of ventilation and sanitary blocks due to the use of shortened plates, as well as making these openings of standard width and position in plan when molding products.

7. The production technology ensures strict observance of the specified geometric parameters.

8. Estimated uniformly distributed load without dead weight for the entire range from 400 to 2000 kgf/m2.

Product range

Table 1

Floor slabs 1197 mm wide

Thickness, mm Length, m Weight, kg

120 mm 2.1 to 6.3 565 to 1700

1.8 to 9.6

From 705 to 3790

From 2850 to 5700

Floor slabs 1497 mm wide

1.8 to 9.6

From 940 to 5000

From 3700 to 7400

7.2 to 14

From 5280 to 10260

Brief description and characteristics of the equipment

1. Production decks (Fig. 4)

Rice. 4 Technological floor device: 1 - threaded stud; 2 - base (foundation); 3 - channel; 4 - reinforcing mesh; 5 - metal-plastic pipe for heating; 6 - concrete screed; 7 - insulation and concrete screed; 8 - metal sheet coating

The concrete base under the technological floor must be perfectly flat and have a slight slope towards the sewer. The floor is heated by an electric cable or hot water up to +60°C. For enterprises that have their own boiler room, it is more profitable to use water heating. In addition, with water heating, the floor heats up faster. The technological floor is a complex engineering structure that must withstand the weight of the molded reinforced concrete products. Therefore, the thickness of the metal sheet is 12-14 mm. Due to a thermal change in the length of the metal sheet (up to 10 cm on a hundred-meter track), the sheet is fixed with metal plates with a millimeter gap. The preparation and welding of a metal sheet should be carried out at the highest level, since the cleaner the surface of the sheet is processed, the smoother the ceiling surface of the plate.

2. Slipformer (Fig. 5)

Rice. 5 Slipformer

Forming machine - Slipformer (w = 6200kg) - designed for the manufacture of hollow core slabs. The machine is equipped with all the necessary equipment, including accessories such as electrical cables, cable drum, water tank and top surface smoothing device - finisher.

The required slab thickness is achieved by replacing the pipe-formwork kit (replacement takes about 1 hour). The electro-hydraulic control of the machine is designed for the work of one operator.

The machine is equipped with four drive wheels with electric drive and a variator, which provides a variety of travel and molding speeds depending on the type of floor slab being produced and the concrete mixture used. Usually the speed varies from 1.2 to 1.9 m/min.

The machine is equipped with one fixed front and one hydraulic rear concrete mix hopper. It is also equipped with two adjustable power vibrators. The machine has one cable reel with hydraulic drive and complete with electric cable (maximum length 220 m). The finisher is provided with a mounting device and electrical connection.

The pipe-formwork set is equipped with a hydraulic drive, the side formwork elements are suspended, which ensures good grip with the guides. Concrete is fed through a double hopper with two controlled outlets.

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manually (the volume of concrete for each socket is 2 cubic meters). There is one galvanized water tank.

The machine is configured according to the type of concrete available at the plant.

3. Aspirator for concrete (Fig. 6)

Rice. 6 Concrete aspirator

The aspirator is designed to remove uncured (fresh) concrete (w=5000kg, 6000x1820x2840) and is used for cutting profiles in slabs and manufacturing slabs with protruding reinforcement. The aspirator can also be used to clean the floor along the rails as well as between production stands. The drive has two forward speeds and two reverse speeds. Low speed is 6.6 m/min, high speed is 42 m/min.

The aspirator includes:

1. One built-in filter and filter housing including:

10 m2 filter surface

Polyester needle and felt filter with a microporous water and oil repellent outer layer

Automatic valve that changes bag filters with air injection every 18 seconds

Waste container under the filter

Concrete separator located in front of the outlet.

2. Aspiration device in a soundproof housing. Maximum air supply - 36 kPa, motor 11 kW.

3. Centrifugal pump and one additional tank for water nozzle.

4. One 500L galvanized water tank.

Suction nozzle with built-in manually operated water nozzle and

spring balancing device attached to the crossbar, allows for transverse and longitudinal movement. Waste container with a capacity of 1090 l. equipped with two pneumatic sealing valves. The container has a hook that facilitates its lifting, as well as a device for cleaning the container by means of a lift. The height-adjustable work platform is designed to clean the rails. The aspirator has a hook with an eyelet, an air compressor with a capacity of 50 liters, an electric switch and a control box with the possibility of installing up to 4 remotes.

4. Multifunctional trolley (Fig. 7)

Rice. 7 Multifunctional trolley

The trolley (w=2450kg, 3237x1646x2506) is powered by a battery, performing the following three functions:

1. Stretching of reinforcing ropes and wire along production stands

2. Lubrication of production stands

3. Cleaning of production stands

The machine is equipped with: an anchor plate for fastening cables and fittings, a scraper for cleaning production stands, a spray gun for applying a lubricant, a hand brake.

5. Automatic plotter (marking device) (Fig. 8)

Rice. 8 Plotter

The plotter (w = 600 kg, 1600x1750x1220) is designed for automatic marking of plates and drawing drawings on them according to any geometric data made in exD format (working speed 24 m/min), for example, cutting angle, cut-out areas and project identification number. The plotter control panel is touch-sensitive. Slab data can be transferred to the plotter using any medium -

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or by connecting to a network wirelessly. For measurements with an accuracy of ±1 mm, a laser is used.

6. Universal sawing machine (Fig. 9)

Rice. 9 Universal Sawing Machine

This sawing machine (w=7500kg, 5100x1880x2320) allows you to saw hardened boards of the required length and at any angle. The machine uses 900-1300 mm discs with a diamond cutting edge; discs are designed for sawing boards with a maximum thickness of 500 mm. The speed of the machine is 0-40 m/min. Sawing speed 0-3 m / min, there is a variety of adjustments. The sawing speed is set automatically by economical adjustment of the saw motor power. Cooling water is supplied at a rate of 60 liters per minute. The cutting disc is cooled on both sides by jets regulated by a pressure and flow sensor installed in the water supply system. The front mounted nozzles can be easily rotated for quick saw blade changes. The sawing speed is adjustable for optimal operation.

The sawing machine has the following characteristics:

1. Electric motors for precision movement.

2. The sawing machine is fully automatic.

3. The operator only needs to enter the cutting angle.

4. Manual positioning is done with a laser beam.

7. Saw for fresh concrete (Fig. 10)

Rice. 10 Fresh concrete saw

Manual saw (m= 650 kg, 2240x1932x1622) for slitting the fresh concrete mix in order to obtain slabs of non-standard widths different from those specified in the molding machine. The maximum plate height is 500 mm. The saw blade is electrically driven. To save money, the used diamond blade (1100-1300) can be recycled. Positioning and movement of the machine is carried out manually. The saw moves along the stand on rollers, and is supplied with power by means of a cable.

The use of such a technological process allows:

Provide increased bearing capacity of floor slabs (since reinforcement is carried out by prestressed reinforcement)

Ensure high flatness of the upper surface due to the forced smoothing of the surface of the plates

Ensure strict observance of the specified geometric parameters

To produce slabs with high strength characteristics due to the forced compaction of the lower and upper layers of concrete, etc.

We have considered modern technological lines for the production of floor slabs. These technologies meet most of the requirements for modern precast concrete production. Therefore, they are promising, i.e. their use allows the enterprises of efficiency, reinforced concrete, etc. be competitive and fully meet the needs of the customer.

Literature

1. Utkin VL New technologies of the construction industry. - M. : Russian publishing house, 2004. - 116 p.

2. http://www.echo-engineering.net/ - equipment manufacturer (Belgium)

3. A. A. Borshchevsky, A.S. Ilyin; Mechanical equipment for the production of building materials and products. Textbook for universities on special. “Production is building. ed. and structures. - M: Alliance Publishing House, 2009. - 368 pp.: ill.

1. Utkin V. L. New technologies of the building industry. - M: the Russian publishing house, 2004. - 116 with.

2. http://www.echo-engineering.net/ - the manufacturer of the equipment (Belgium)

3. A.A. Borschevsky, A.S. Ilyin; the Mechanical equipment for the manufacture of building materials and products. The textbook for high schools on “Pr-in builds. ed. and designs. Publishing house the Alliance, 2009. - 368c.: silt.

Key words: ceilings, molding, technologies, formwork, equipment, production lines, slabs

Keywords: overlappings, formation, technologies, a timbering, the equipment, technological lines, plates

The article was submitted by the Editorial Board of the Vestnik MGSU

Manufacture by formless molding on long stands of a wide range of reinforced concrete products

On the lines of formless molding (LBF), the production of hollow flooring slabs, piles, columns, crossbars, beams, lintels, airfield slabs (PAGs), side stone, and fence sections has been mastered. All products undergo design and documentary study in the leading specialized design organizations of the country.

A unique technology for the production of road slabs has been patented in full compliance with the profile GOSTs. In the work - documentation for the production of power transmission poles.

Development, production and supply of equipment for formworkless molding of reinforced concrete products on long stands is one of the priority areas of activity.

Product range

Performance

Shutterless Forming Line ST 1500
(6 lanes of 90 meters, product width - up to 1500 mm)

Product type	Unit measurements	Performance
		per day	per month	per year (250 days)
floor slabs width 1500 mm, height 220 mm	Linear meters	540	11 340	136 000
	M 3	178	3 738	44 856
floor slab width 1200 mm, height 220mm	Linear meters	540	11 340	136 000
	M 3	142	2 982	35 784
piles 300mm x 300mm	Linear meters	2 160	45 360	544 320
	M 3	194	4 074	48 900
crossbars 310 mm x 250 mm	Linear meters	2 160	45 360	544 320
	M 3	194	4 074	48 900
crossbars 400mm x 250mm	Linear meters	1 620	34 020	408 240
	M 3	162	3 402	40 824

In total more than 30 standard sizes of products.

Note: as the number, width, and length of lanes change, performance changes.

Specifications

Characteristic	LBF-1500
Installed power (minimum), kW * depending on configuration	200 *
Workshop overall dimensions (minimum), m	18 x 90
Height to the GAK crane, m	6
lifting equipment
Number of overhead cranes, pcs.	2
Overhead crane lifting capacity, not less than, tons	10

Service staff

The number of service personnel is given for one shift

№	the name of the operation	Number of workers, people
1.	Cleaning and lubrication of the track, laying out the wire with tension, covering with a protective coating, transferring stress to concrete, export of finished products to the warehouse	3
2.	Forming, washing the forming machine	2
3.	Cutting	1
4.	Overhead crane control	2
Total		8

Brief description and principle of operation

The technological process begins with the cleaning of one of the molding tracks with a specialized machine for cleaning the tracks and spraying lubricant on it in the form of a fine air dispersion. The average cleaning speed with a special machine is 6 m/min. Cleaning time - 15 minutes. The treadmill is lubricated immediately after cleaning with a knapsack pump.

Track cleaning and lubrication

After that, using a wire laying machine, the rebar is unwound from the reels and laid out on the track.

After laying out the required amount of wire (in accordance with the album of working drawings), it is tensioned using a hydraulic tensioning group. The ends of the wire are fixed in the die holes of the stops using collet clamps. The ends of the wire are cut off with a manual cutting machine and covered with a protective cover, after which the track is ready for molding. On average, it takes no more than 70 minutes to lay out the reinforcing wire, taking into account the time for filling, disembarking heads, trimming the ends and tensioning the wire.

With the help of an overhead crane (with a lifting capacity of at least 10 tons), the forming machine is installed on the rails of the forming track behind the stops of the beginning of the track. A power cable is unwound from a hydraulic cable drum and powered from a 380 V workshop network. The traction cable is unwound from the traction winch of the machine and fixed to the anchor at the end of the track.

Ready-mixed concrete is fed into the storage hopper of the forming machine with the help of a concrete supply tank by an overhead crane. The traction winch and vibrators are switched on. During the continuous process of molding the track, the concrete mixture is timely fed into the storage hopper. The average speed of the molding machine in the production of hollow core slabs is 1.5 m/min; taking into account the time for installing the machine, we take 90 minutes. After the completion of the molding of one track, the molding machine is installed with a crane at the washing station and thoroughly washed by the high-pressure machine washing machine from the remains of the concrete mixture. The track with the tape of the molded product is covered with a special covering material using a trolley for laying out the protective coating and left for the duration of the heat treatment process.

heat treatment

The heat treatment process goes according to the following scheme: 2 hours temperature rise to 60-65˚С, 8 hours exposure, 6 hours cooling.
After the concrete product reaches the transfer strength, the covering material is removed, and the tape is examined by the workers of the factory laboratory, who mark the tape into segments of the design length for subsequent cutting.
After that, a hydraulic block for relieving stress from 3 cylinders produces a smooth release and transfer of the tension force of the reinforcement to the concrete of the product. Then the reinforcement is cut, this is done using a manual hydraulic group and takes, taking into account the time it takes to put it into working position, no more than 10 minutes.

The cutting of the strip is carried out by a special plate cross-cutting machine equipped with a high-strength diamond-coated cut-off wheel.

The cutting machine is installed by a crane on the rails at the beginning of the track. A power cable is wound from the hydraulic drum and powered from a 380 V workshop network. The required amount of water is poured into the tank. Cutting is carried out by the operator of the cutting machine in manual or automatic mode. The duration of cutting a hollow-core slab with a diamond-coated cutting disc is about 2 minutes. We take the estimated length of the slab as 6mm, from here we get 14 cuts, the time for cutting the slabs on one track is about 30 minutes; together with the operation of installing the machine and moving it, we take 70 minutes.

Finished slabs are stacked on a cargo trolley by an overhead crane using a technological gripper for transportation of slabs and transported to the warehouse of finished products. The side surfaces of the plates are marked by QCD employees in the prescribed manner.

After forming each track, the machine is installed on the stand, after which the forming machine and the punch-matrix are washed. Rinsing is carried out with a jet of water at a pressure of 180 - 200 atmospheres. This operation takes about 20 minutes.

Washing the forming machine

Price

1. Technological equipment - from 25 million rubles (depending on configuration)
2. Equipment for technological floors - from 8 million rubles (depending on the configuration)
3. Services (installation, commissioning - from 5 million rubles (depending on the scope of work).

The prices on this site are for reference only.

A commercial offer is made to the Customer in the course of negotiations and is valid for 30 days from the date of its presentation.

You can see an example

Other conditions

The warranty period is 12 months.

OAO 345 Mechanical Plant offers to organize a visit of our specialists free of charge to coordinate the placement of the LBF-1500 at the Customer's site.

Other conditions are agreed upon at the conclusion of the contract.

Today, the technology of non-formwork formation of reinforced concrete products has become quite widespread. It has been known for a long time - since the late 1970s, when a large-scale all-Union construction of panel houses was carried out. But under pressure from certain circles, the technology became of little use, and in the 90s it practically ceased to be used in Russia.

Until recently, the main suppliers of equipment for the production of reinforced concrete products using the technology of formless formation were three foreign companies that provided the supply of vibropresses, extruders and splitformers.

Features of the lines of non-formwork formation of reinforced concrete products

BOF lines are a specialized set of equipment that allows for the formation of beams, piles, lintels of road and hollow slabs, as well as other reinforced concrete products for wide use in various fields of construction. At the same time, the use of BOF is far from always economically feasible - this is due to the technical features of the equipment, which wears out quite quickly, after which it requires maintenance or expensive overhaul.

The design of the splitformer used in the formation of reinforced concrete products using formless technology provides for the installation of vibrators, which form the main equipment of the forming machine. The disadvantage of this design is the need for a long high-precision adjustment, further maintenance also takes a lot of time.

The mechanism of operation of a classic vibropress is much simpler than a splitformer, first of all, it consists in the gradual compaction of the mixture in front of the shaping tool. At the same time, the BOV equipment makes very high demands on the qualitative composition of the concrete mix. If the quality of the mixture is insufficient or if unforeseen fractions, bolts and even small stones get into the mixture, the equipment may produce defective products or even fail.

The high quality of the concrete mixture and the absence of impurities in it is not the only requirement for production using the technology of formless formation of reinforced concrete products. Particular attention should be paid to the systematic maintenance of the equipment. After each stage of production, it must undergo high-quality cleaning in compliance with routine maintenance.

The key disadvantage is the high price

The cost of the BOF production line is much higher (on average, about 55-65 million rubles) than the organization of production by means of "classic" technological lines (a set of equipment), which the Intek Plant offers on a turnkey basis. It is also worth noting the high cost of components for formworkless molding lines, in addition, all this can be aggravated by the protracted delivery time of the necessary components.

Investments in the production of reinforced concrete products using the technology of formless molding can only be justified at large enterprises provided with a constant flow of orders, for example, long-term implementation of large infrastructure projects of regional or national importance, where all regulations for the technical operation of this equipment are strictly observed.

Of the minuses, it is also worth noting the complexity of modernizing the BOF line. The production of various types of reinforced concrete products on such lines is possible with the help of special removable molding equipment, but it is simply not possible to reconfigure the BOF line for another type of production without huge investments. In addition, there are difficulties in the procedure for replacing tooling on a splitformer, and the cost of tooling for the production of one product is at least 1 million rubles.