CH629996A5 - Pretensioning bench - Google Patents

Description

The invention relates to a prestressing bench for the production of elongated products.

The technology for manufacturing elongated prestressed concrete products, such as beams, joists, railway ties, etc., has evolved considerably in recent years.

The prestressing benches have reached considerable lengths, reaching 60 to 100 m, and the products are produced in series on these benches.

According to the traditional technique, the molds occupy the length s of the bench and the products are separated by partitions in the form of combs which overlap the threads or are threaded thereon. In this technique, the formwork material consists of mold elements having approximately the length of the prestressing bench, and these elements rest directly on the ground or the base slab.

Despite the many advantages of this technique, certain drawbacks are very important: mold bases, for example made of plastic, must be provided and these mold bases are subject to wear and must be regularly cleaned, which is not without problems, because it is then necessary to open the molds and handle the elements by means of external systems; it is impossible to vibrate all of the forms and it is only possible to vibrate the concrete inside the molds, in particular by needle vibrators, the action of which is insufficiently homogeneous and effectiveness is limited.

Finally, the demolding of the products poses problems when it is desired to adopt more sophisticated forms of products, such as in particular the shapes of certain crosspieces or beams of the type described in French patent No. 77.27722 filed on September 14, 1977 in the name of the incumbent. Indeed, if such a shape is molded according to the traditional technique, the jointing between the mold base and the lateral impressions poses problems which can go as far as the practical impossibility of producing said shapes, for lack of being able to demold them in the frame. of a truly industrialized process.

According to another technology described in particular in French patents N ° 73.44993 of December 17, 1973 and N ° 77.09136 of March 28, 1977, both deposited in the name of the holder, the molds no longer have the length of the bench, but are made up of 35 modules or batteries of parallel molds or modules, which are mounted on a support by means of sliding pads allowing the relative longitudinal displacement of the modules when the wires are released. This technology allows the elimination of mold bottoms in plastic blocks, the simplification of combs io for lengthening the beams and positioning of the wires; it also allows the vibration of the molds themselves and not only of the concrete poured into the molds.

Thus is solved, in particular, the problem of manufacturing products such as the beam described in patent No. 77.27711 of 45 September 14, 1977 cited above.

One of the particularities of this technology by modules or formwork batteries lies in their defined length. Each battery can comprise a certain number of forms each capable of ensuring the manufacture of a beam or a product of a well defined length. A prestressing bench can include several batteries of different lengths from one to the other.

This characteristic and the interchangeability of the batteries make it possible to manufacture industrially, under the best conditions, the range of beams best suited to the needs of the market. s5 This technology does not however make it possible to manufacture the beams comprising so-called seam steels, because the mold base is fixed.

In the traditional technique, the seam steels are fixed to the mold base in a slot made in a solid mold base 60 made of neoprene or similar plastic material, and they penetrate several centimeters into this mold base. When the molds are tightened, the slot closes on the seam steels due to the elasticity of the plastic mold base and the casting can be carried out suitably.

65 The object of the present invention is an embodiment of the molds applicable with one or other of the known technologies thus described and allowing, among other advantages, the manufacture of beams of the type described in the aforementioned patent N ° 77.27722, as well as

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other products of sophisticated shape, whether or not provided with sewing irons or, in general, irons or elements extending beyond the mold base.

The prestressing bench according to the invention is characterized in that the flanks of two neighboring molds are mounted integral with one another on a longitudinal plate sliding on a chassis under the action of cleats carried by at least one bar perpendicular to the axis of the molds and sliding along its axis in said chassis, said tabs cooperating with stops integral with said plates and said bar being actuated in both directions by any appropriate means, the tabs of the sliding bar and the stops of the mold-carrier plates being arranged such that a displacement of the bar in one direction causes the closure of all the molds of a module and a displacement in the opposite direction causes the opening of all said molds.

The invention is particularly usable in combination with the battery technology of molds described in the aforementioned patents No. 73.44993 and No. 77.09136. In this case, the fixed support frame of the movable mold sides is a mold battery frame resting by means of shock absorbers on a support frame secured to civil engineering. However, the invention can also be used in combination with the traditional technique, that is to say with very long molds, the fixed frame resting directly on civil engineering.

The arrangements of the invention are more fully described, by way of example, with reference to the appended drawing, in which:

fig. 1 shows in longitudinal section a preferred embodiment of opening molds according to the invention;

fig. 2 is a detailed view of FIG. 1;

fig. 3 is a perspective view of a section of beam provided with sewing irons achievable with means of the invention;

fig. 4 to 8 illustrate a block forming the mold end; fig. 4 is a perspective view; fig. 5 and 6 illustrate in section and in elevation with partial section the upper part of the block, and FIGS. 7 and 8 illustrate in section and in elevation with partial section the lower part of the block.

In the example shown, the prestressing bench is of the type in which the molds are arranged in batteries or modules 1 carrying a series of parallel molds 2 formed from the cheeks 3,

the assembly being mounted on a stiffening frame 6 whose lateral parts 7 constitute running rails and which rests by means of shock absorbers-slides 9 on a base support frame 8.

Such a prestressing bench has a series of such modules or batteries 1, aligned one behind the other on the support frame 8 whose length can reach 50 to 100 m.

As explained above, in this technology, the modules normally correspond to the manufacture of a product of defined length: the sides of the molds of each battery are fixed on their chassis and are not tightened on a bottom of the mold. plastic for preparation of casting; on the other hand, the batteries or modules are sliding on the pads 9 and when the prestressing wires are relaxed, they move by longitudinal sliding. Cylinders mounted on the support 8 and cooperating with tabs carried by the chassis 6 allow them to be brought back to their initial position fixed by stops linked to the support chassis 8.

This technology allows the vibration of the mold batteries by external means not shown, which makes it possible to achieve concrete performance higher than that obtained by vibration of the concrete with the vibrating needle.

However, this improvement has the drawback of providing products with very smooth walls, which, in the case of beams, makes it preferable to produce beam walls provided with lateral notches 4, as described in patent N ° 77.27722 of September 14, 1977 cited above; such a beam is shown in fig. 3.

The demolding of such beams is however not easy;

on the other hand, it is not possible to produce beams of the type of FIG. 2, comprising 13 so-called seam steels; in fact, if a mold base consisting of a block of flexible plastic material in which the steels 13 are inserted is retained, one loses one of the advantages of the technology by mold batteries and, on the other On the other hand, there is a problem of jointing between the bottom of the mold and the lateral cavities 4, which can go so far as to make demolding impossible.

However, to be industrially valid, a long prestressing bench must allow both the production of standard products of length defined according to a range appropriate to the market, as well as products of particular lengths and special products such as steel beams. seam 13 and lateral reliefs 4 of FIG. 3. The various problems raised by these products must therefore be solved on the same basic material.

There is shown in Figs. 1 and 2 the provisions of the invention allowing the production of beams provided with sewing steels such as steels 13 of FIG. 3.

In fig. 1, it can be seen that the chassis 6 of the battery 1 carries, in addition, at least one transverse bar 14 sliding along its axis and driven by the end jacks 15 and 16. This bar carries the tabs 17.

Referring to fig. 2, we see that the flanks (or cheeks) contiguous 3a, 3b of two neighboring molds are connected by plates 18 of which they are integral.

The plates 18 rest and slide on the frame 6 (fig. 1); they carry stops 19 cooperating with the cleats 17.

The tabs 17 and the stops 19 are arranged so that a movement of the bar 14 to the right causes successive opening of all the molds, while a movement to the left causes their tightening or closing.

In the example shown, this result is obtained with tabs 17 of different lengths, while the stops 19a, 19b carried by a plate 18 are spaced the same length for all the plates.

The distance between the left ends of the cleats 17 is equal to the center distance of the molds when tightened, while the distance between the right ends of the cleats 17 increases from one stop to the next by an amount corresponding to the opening mold sought, for example 0.5 cm from the cleat 17 to the next.

An equivalent result could be obtained with two tabs 17 per plate 18, one cooperating with the stop 19a, the other with the stop 19b; another solution consists in having cleats 17 of equal length equidistant to the length of the center distance of the molds and associated with stops 19a, 19b whose spacing varies from one plate 18 to the next, regularly, or increasing , or decreasing.

The invention is not limited to the embodiment shown. Nevertheless, it is advantageous, for reasons of stiffening of the stops 19 and of stability of the molds, to connect the stops 19a and 19b to each other by walls 19c so as to form boxes whose walls are sufficiently large to be crossed by the bar 14; the lower parts 19d then prevent the walls of the molds from tilting laterally.

In the case where the product to be produced does not include the seam steels 13 of FIG. 3, the bottom of the mold can be formed by the lateral parts of the adjacent plates 18 which come together during tightening, or also by metal parts 20 provided with any relief or desired shape.

The system of the invention therefore ensures easy demolding, in particular for the production of beams with lateral reliefs 4, as shown in FIG. 3.

In the case where seam steels such as the steels 13 of FIG. 3, the mold base will include a flexible seal 21, sandwiched between the plate 18 and the metal bottom pieces 20, this seal being formed of two parts, each linked to a mold flank, which come together when the mold is tightened.

This solution allows the production of a notched beam provided with sewing steels. The part of the mold which is subject to relatively frequent replacements is reduced to the seal 21.

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For producing the ends of molds, the invention provides for the use of comb blocks (FIGS. 4 to 8) made of elastic plastic, Neoprene for example.

As shown in fig. 4 to 8, these blocks have a non-negligible length, of the order of 20 cm, so as to leave between the beams molded in the same mold a length of free steel of the same order and to form the ends of the beams, avoiding losses of milt. They are also used for positioning steels through their channels 23.

As shown, these blocks are formed of two superimposed parts, a lower part 29 shown in detail in FIGS. 7 and 8 and an upper part 30 shown in FIGS. 5 and 6.

The upper part fits on the lower part by its relief 24 corresponding to the recesses 25 in the lower part, so that the seal is ensured, as well as the maintenance in position of the upper part.

The lower part occupies the bottom of the mold up to the level of the lowest prestressing wire; it is provided with at least borders of dimensions greater than those of the closed mold base, to be compressed when the mold is closed. To this end, a vertical slot 26 is provided which extends over the entire length of the block at the bottom of the latter, as well as reliefs 27, 28 at the ends of the block 29 and 31 on the edge of its face. superior. This arrangement allows the block 29 to adapt to the mold base reliefs corresponding to the notches 4 in FIG. 3 and ensure sealing without requiring too high a compressive force.

The upper part 30 of the block has a longitudinal lower slot 32 in line with the wires. If the wires are superimposed as shown, a single slit is enough; otherwise, several slots 32 will be provided. These slots have longitudinal grooves 23 at the location of the wires, to ensure the positioning of the latter. When the mold is closed, the slots 32 close by elasticity.

A housing 34 is provided in the middle zone of the block 30, the bottom of this housing being at a level lower than that of the highest wire. Said wire is therefore accessible in the housing 34, which makes it possible to grasp it with the demolding and lifting machine, in order to carry out the lifting of the beams.

The shape of the end block described above, forming a comb in two parts, ensures with its grooves and its reliefs or bosses, the seal between the comb, the lateral planes of the mold and the bottom of the mold.

Such end blocks can be used in any location of the mold, which makes it possible to manufacture beams or other products of special dimensions, or different from each other.

(s The mold release can be carried out before or after sectioning the prestressing wires, and can be combined with lifting using the said wires.

The prestressing bench of the invention obviously includes all the provisions specific to this type of device and which, for clarity, have not been described or shown.

Thus, it includes means for placing and tensioning the prestressing wires, means for concreting, heating or baking, cutting up, lifting, etc.

The heating or steaming means are shown diagrammatically at 22, 25 fig. 2. They can be heat transfer fluid distribution pipes or electrical resistances. It is also possible to provide lower radiant panels, etc.

As indicated above, the provisions of the invention are applicable to a traditional bench and in particular to a bench provided with 30 very long molds. In this case, the chassis 6, instead of constituting the chassis of a battery or module mounted on the shock absorbers 9, will be directly fixed on the base support 8 or on the civil engineering.

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3 sheets of drawings

Claims (11)

629,996 1. Prestressing bench for the production of elongated products, characterized in that the sides of two neighboring molds (2) are mounted integral with one another on a longitudinal plate (18) sliding on a frame (6) under the action of cleats (17) carried by at least one bar (14) perpendicular to the axis of the molds and sliding along its axis in said chassis, said tabs (17) cooperating with stops (19a, 19b) integral with said plates and said bar being actuated in both directions by any suitable means, the catches of the sliding bar and the stops of the mold-holder plates being arranged so that a displacement of the bar in one direction causes the closing of all the molds of a module and a movement in the opposite direction causes all of said molds to open. 2. Prestressing bench according to claim 1, characterized in that the stops have the form of plates traversed by the cleat bars. 2 3. Prestressing bench according to one of claims 1 or 2, characterized in that the two stops carried by a plate and crossed by a bar are joined together and stiffened by at least one wall. 4. Prestressing bench according to one of claims 1 to 3, characterized in that the stops are equidistant, the cleats being of unequal lengths, the lateral faces of one side of the cleats being equidistant from the length of the center distance of the molds, while the distance between the lateral faces of the other end of the cleats increases from one stop to the next by an amount equal to the desired opening. 5. Prestressing bench according to one of claims 1 to 3, characterized in that the tabs are of equal length, equidistant from the center-to-center length of the molds, and cooperate with stops integral with the sliding plates whose spacing varies regularly and in the same direction from one plate to the next. 6. Prestressing bench according to one of claims 1 to 5, characterized in that each mold base is divided into two parts each linked to one of the sides of the mold, and each of these parts is formed by a seal flexible clamped between the base plate of a pair of flanks of neighboring molds and a metal element at the bottom of the mold secured to one of the flanks. 7. Prestressing bench according to one of claims 1 to 6, characterized in that the ends of the molds are produced in the form of blocks of elastic material formed by two superposed parts, one occupying the bottom of the mold up to the level of the first prestressing wire, the other coming to adapt to the first and being provided with at least one channel slot for the passage and positioning of the wires. 8. Prestressing bench according to claim 7, characterized in that the upper part of the block forming the mold end is provided with a median housing whose depth is sufficient to expose at least one of the prestressing wires. 9. Prestressing bench according to one of claims 7 or 8, characterized in that the lower part of the block is provided with raised edges intended to be compressed when the mold is closed. 10. Prestressing bench according to one of claims 7 to 9, characterized in that the lower part of the block is provided with a longitudinal vertical slot open on the lower face of said part. 11. Prestressing bench according to one of claims 7 to 10, characterized in that the length of the block is 15 to 25 cm.