EP0783065A1 - Shuttering with forming panels and automatic tensioning means - Google Patents

Abstract

The shuttering assembly consists of two parallel panels (10,12) and a locking system with at least one long bolt (18,20) which joins the panels together. The long bolts are fixed to one panel and pass through guides (29) in the other before being locked by a ram which has its body (39) fixed to the second panel and rods (40,42) extending in opposite directions. The tips of the two rods have cam surfaces (110) which interact with matching surfaces on traction members (28,36) on the ends of the long bolts. The cam surfaces on the rods can be on two adjacent forked tips which fit on either side of the long bolts to engage with the traction members, and the ram can be in the form of a hydraulic cylinder.

Description

The present invention relates to a metal formwork used for the construction of walls or other reinforced concrete works.

Such forms are known, of the type comprising two forms arranged substantially parallel to each other and a formwork for tightening the forms comprising at least one tie connecting the two forms, the tie being immobilized in traction by a first end on a first form, the second panel comprising means for axially guiding the tie rod in which it is free to slide.

In the state of the art, the forms are connected to one another by one or more threaded tie rods extending substantially perpendicular to the forms. These tie rods cross the formwork right through and carry at each end a nut which bears against the external surface of the formwork. In order to tighten the forms, and in particular to bring them closer, the nuts are screwed in abutment against the forms, so that the gap between the latter decreases and that they come to be applied against spacers.

Such an operation is relatively tedious and long. In addition, it requires the presence of an operator at the rear of each section, which makes it difficult to adjust their spacing when the backward movement of at least one section is insufficient for an operator to be able to access it. In addition, it is common to use an impact wrench to screw the nuts. This use causes noise pollution.

The invention aims to provide a formwork, the approximation and tightening of the forms can be done in a simple and convenient manner by a single operator.

To this end, the invention relates to a formwork of the aforementioned type, characterized in that the tightening device for the formwork comprises a jack, which is arranged substantially transversely to the tie rod, this jack comprising on the one hand, a body fixed on the second form and on the other hand, a movable jack rod provided at its end with a cam actuating surface for the tie rod, which tie rod comprises at its second end a cam follower adapted to cooperate with said cam in order to cause the two panels to be tightened when the actuator is actuated.

• la contre-came est formée de deux parties coplanaires disposées de part et d'autre de l'axe du tirant et la surface de came est en deux parties coplanaires portées par deux dents d'une fourchette prolongeant la tige de vérin, le tirant étant disposé entre les deux dents de la fourchette,
• la contre-came est portée par un manchon traversé de part en part par le tirant et le tirant comporte, à sa seconde extrémité, une butée de blocage du manchon,
• la seconde banche comporte un passage traversant de guidage du tirant,
• le tirant est une tige filetée,
• la première banche comporte un dispositif de blocage unidirectionnel du tirant dans lequel est immobilisé en traction la première extrémité du tirant,
• le dispositif de blocage unidirectionnel comporte deux demi-écrous délimitant un conduit taraudé de réception du tirant et présentant à leur extrémité un chanfrein extérieur tronconique, ces deux demi-écrous étant reçus libres dans une cage dont la paroi d'extrémité en regard de l'extrémité chanfreinée des deux demi-écrous comporte un passage central pour le tirant et forme un siège concave à surface d'appui conique, le dispositif de blocage comportant en outre un ressort hélicoïdal axial prenant appui sur ladite cage et sollicitant les deux demi-écrous vers le siège conique, les deux demi-écrous étant déplaçables entre une position de blocage dans laquelle ils forment coin entre le siège et le tirant lorsque ce dernier est tiré hors du dispositif, et une position de libération dans laquelle ils sont dégagés du siège et du tirant lorsque ce dernier est poussé dans le dispositif,
• le coffrage comporte une paire de tirants disposés sensiblement parallèlement et reliant les deux banches, chaque tirant étant immobilisé en traction à une première extrémité sur la première banche, la seconde banche comportant des moyens de guidage axial de chaque tirant dans lesquels chaque tirant est libre de coulisser, et le vérin est un vérin à double tige dont chaque tige est munie à son extrémité d'une surface de came adaptée pour coopérer avec une contre-came portée par un tirant correspondant,
• le vérin est un vérin hydraulique.

According to particular embodiments, the invention may include one or more of the following characteristics:

• the cam follower is formed of two coplanar parts arranged on either side of the axis of the tie rod and the cam surface is in two coplanar parts carried by two teeth of a fork extending the cylinder rod, the tie rod being placed between the two teeth of the fork,
• the cam follower is carried by a sleeve traversed right through by the tie rod and the tie rod comprises, at its second end, a stop for blocking the sleeve,
• the second section has a through passage for guiding the tie rod,
• the tie rod is a threaded rod,
• the first section comprises a unidirectional blocking device for the tie rod in which the first end of the tie rod is immobilized in traction,
• the unidirectional blocking device comprises two half-nuts delimiting a threaded conduit for receiving the tie rod and having at their end a frustoconical external chamfer, these two half-nuts being received free in a cage whose end wall opposite the chamfered end of the two half-nuts has a central passage for the tie rod and forms a concave seat with a conical support surface, the locking device further comprising an axial helical spring bearing on said cage and urging the two half-nuts towards the conical seat, the two half-nuts being movable between a blocking position in which they form a wedge between the seat and the tie rod when the latter is pulled out of the device, and a release position in which they are released from the seat and the tie rod when the latter is pushed into the device,
• the formwork comprises a pair of tie rods arranged substantially parallel and connecting the two forms, each tie rod being immobilized in traction at a first end on the first branch, the second branch comprising means for axially guiding each tie rod in which each tie rod is free slide, and the jack is a double rod jack, each rod of which is provided at its end with a cam surface adapted to cooperate with a cam follower carried by a corresponding tie rod,
• the cylinder is a hydraulic cylinder.

• la figure 1 est une vue en coupe transversale d'un coffrage selon l'invention, avant réglage de l'écartement des banches ;
• la figure 2 est une vue en coupe longitudinale d'un dispositif de blocage unidirectionnel entrant dans la composition du coffrage de la figure 1 ;
• la figure 3 est une vue partielle en coupe prise suivant la ligne III-III de la figure 1 ;
• les figures 4 et 5 sont des vues analogues à celle de la figure 2, représentées à des stades différents de fonctionnement ;
• la figure 6 est une vue analogue à celle de la figure 1, après réglage de l'écartement des banches ; et
• la figure 7 est une vue partielle en coupe prise suivant la ligne VII-VII de la figure 6.

The invention will be better understood on reading the description which follows, given solely by way of example, and made with reference to the drawings in which:

• Figure 1 is a cross-sectional view of a formwork according to the invention, before adjusting the spacing of the forms;
• Figure 2 is a longitudinal sectional view of a unidirectional locking device used in the composition of the formwork of Figure 1;
• Figure 3 is a partial sectional view taken along line III-III of Figure 1;
• Figures 4 and 5 are views similar to that of Figure 2, shown at different stages of operation;
• Figure 6 is a view similar to that of Figure 1, after adjusting the spacing of the formwork; and
• FIG. 7 is a partial sectional view taken along line VII-VII of FIG. 6.

The formwork shown in Figure 1 has two forms 10, 12, arranged vertically, face to face and substantially parallel to each other. Each panel comprises a parallelepipedic frame 14 closed on one side by a panel 16 delimiting a formwork surface.

The forms are connected together by a tightening and tightening device comprising two pairs of tie rods, arranged two by two in two vertical parallel planes. In the figures, only two tie rods, denoted respectively 18 and 20, are shown. They are contained in the same vertical plane P (plane of Figures 1 and 6), perpendicular to the shuttering surfaces 16. These tie rods are formed by threaded rods.

In its upper part, the first section 10 comprises a support 22 in which is fixed a device 24 for unidirectional locking of the tie rod 18. The device will be described in detail with reference to FIGS. 2, 4 and 5.

In its upper part, the second section 12 also comprises a support 26, in which is integrated a device 28 for pulling the tie rod 18. The device 28 is disposed behind a passage 29 for guiding the tie rod in which the latter is free to slide.

The devices 24 and 28 are arranged at substantially the same height, so that the tie rod 18 extends substantially horizontally.

The tie rod 20 is arranged in the lower part of the formwork. It crosses the shuttering walls 16 along guide passages 30, 32 behind which are welded reinforcement angles 30A, 32A. The tie rod is immobilized in traction at a first end by a unidirectional locking device 34 similar to the device 24. The locking device 34 is for example welded to the frame 14 of the first section. The second end of the tie rod 20 is engaged in a traction device 36, similar to the device 28 and carried by the second panel 12.

A hydraulic cylinder 38 with double rod is integrated in the second section 12 to actuate the traction devices 28 and 36. It is controlled by a hydraulic hand pump not shown. The axis of this jack extends in the plane P defined by the tie rods 18 and 20 and is arranged substantially perpendicular to the tie rods. The body of the jack 39 is fixed to the structure of the panel 12, while the actuating rods, denoted respectively 40 and 42, are directed upwards and downwards in order to simultaneously actuate the traction devices 28 and 36 This cylinder allows the simultaneous movement of the two actuating rods 40, 42 in opposite directions.

In Figure 2 is shown the device 24 for unidirectional locking of the tie rod 18. The device 34 is identical.

Such a device comprises a cylindrical cage 50 open at its two ends in which are received two free half-nuts 52, 54 and a helical spring 56.

The cage 50 comprises a tube 58 closed at its first end by a sleeve 60 and at its second end by a crown 62 forming the bottom.

The sleeve 60 has an axial passage 64 for guiding the tie rod 18. It has on its inner face a conical bearing surface 66 bordering the passage 64. It thus forms a concave blocking seat for the two half-nuts 52,54.

These two half-nuts are identical. They are each formed of a half-sleeve, cut along a longitudinal plane.

The two associated half-nuts define an axial duct 68 for receiving the tie rod 18. This duct is tapped over its entire length.

Each half-nut has two successive sections 70, 72 of substantially equal length and of different thickness. The section 70, oriented towards the seat 60 has an external overthickness 74. It has at its end opposite the seat 60, an external frustoconical chamfer 76, whose angle at the top is substantially equal to that of the bearing surface 66 At this same end, the axial duct 68 is flared by an internal chamfer 78.

The opposite end of the extra thickness 74 delimits an annular bearing front 80 for the spring 56. A groove 82 with an inclined side wall is also formed externally on the section 72.

As shown in FIG. 2, the spring 56 surrounds the section 72. It is compressed between the bearing front 80 and the crown 62 and urges the two half-nuts 52, 54 against the bearing surface 66. The half nuts thus form a wedge between the seat 60 and the tie rod 18, guaranteeing the immobilization in traction of the latter.

In FIG. 3 is shown in detail the traction device 28 of FIG. 1. This device comprises a sleeve 100 crossed by a cylindrical duct 102 with a smooth wall of diameter slightly greater than that of the tie rod 18. This sleeve has in its side wall outer two grooves 104, 106 symmetrical with respect to the plane P.

The grooves 104, 106 are delimited by flat bottoms 104A, 106A and two banks two by two coplanar. A first bank 104B, 106B (FIG. 1) extends perpendicular to the axis of the sleeve, while the other bank 104C, 106C defines with it a non-zero angle. These two banks 104C, 106C form a two-part cam follower inclined by about 30 ° relative to the axis of the jack. The two parts 104C, 106C of the cam follower are adapted to cooperate with a corresponding cam surface in two parts 110, 112 carried at the end of teeth 114, 116 of a fork 118 extending axially the cylinder rod 40.

The distance between the teeth 114, 116 is substantially equal to the distance separating the bottoms 104A, 106A, the teeth thus being partially received in the grooves 104, 106. The two parts 110, 112 of the cam surface are coplanar and are inclined by relative to the cylinder axis of the same angle as the banks 104C, 106C delimiting the cam follower.

The sleeve 100 and the fork 118 are protected by two side walls 120, 122 of the support 26 and by a front closure wall 124, in which is formed the passage 29 for guiding the tie rod 18. This passage is extended by an overbore 126 for guiding the sleeve 100 in translation. A rear wall 127 of the support 26 has a complementary coaxial passage 128 also ensuring the guiding in translation of the sleeve 100.

The traction device 28 further comprises a locking nut 130 associated with a lock nut 132 screwed to the end of the tie rod 18 beyond the sleeve 100. The nut and the lock nut form a sleeve locking stop on the tie rod 18.

The traction device 36 is similar to the device 28, the fork extending the cylinder rod 42. However, the device 36 is mounted turned 180 ° relative to the axis of the tie rod.

In order to arrange the formwork for casting, the two forms are placed face to face, for example using a crane. An operator then introduces the tie rods 18 and 20 from the rear of the second section 12 through the sleeves 100. Tubular spacers 134, 136 are then interposed between the forms at the level of the passages of the tie rods. These spacers have lengths corresponding to the desired interval between the forms. The operator then pushes the tie rods 18, 20, through the spacers until their first ends penetrate the passages 64 of the one-way locking devices.

As shown in Figure 4, explaining the operation of the device 24, the end of the tie rod 18, introduced in the direction of the arrow F1, pushes the two half-nuts 52, 54 towards the crown 62 against the action of the spring 56. The two half-nuts then move apart in the direction of the arrows F2, F3. The inner edge of the crown 62 is then received in the groove 82.

The spacing of the half-nuts allows the passage of the tie rod 18, as shown in FIG. 5. The tie rod can thus be put in place, without it being necessary to screw the latter in the two half-nuts.

The tie rod is pushed in until the nuts 130, 132, previously arranged at the other end of the tie rod, come into contact with the sleeve 100.

When the tie rod is released, the two half-nuts 52, 54 tighten in the direction of the arrows F4, F5 (FIG. 2) around the tie rod under the action of the spring 56. The guidance of the two half-nuts is ensured by the conical surface 66 of the seat 60 and by the inclined walls of the groove 82 cooperating with the crown 62. The loosening of the tie rod 18 leads to the state shown in FIG. 2, in which the two half-nuts form a wedge between the seat 60 and the tie rod 18, and thus ensure the traction lock of the tie rod in the direction of the arrow F6 .

The tie rod 20 is mounted and immobilized in a similar manner.

In order to bring the two formwork together and to tighten it, the operator actuates the hydraulic cylinder with two rods, using the hand pump, in order to cause the simultaneous exit of the cylinder rods.

It will then be understood that in each traction device 28, 36, the fork 118 acts on the cam follower 104C, 106C, forming a reaction, by means of the cam surface in two parts 110, 112. During the vertical movement of the fork 118, the sleeve 100 moves horizontally relative to the panel 12 and bears against the nut 130 screwed onto the tie rod. The latter being immobilized, at its other end, in the blocking device, the sleeve 100, blocked by the nut 130, cannot move relative to the ground, so that the second section 12 approaches the first section 10 by sliding one or other of the formwork on the ground.

The simultaneous action of the upper 28 and lower 36 traction devices ensures a bringing together of the two forms which remain continuously parallel. When the desired distance between the two forms is reached, as shown in FIG. 6, the spacers 134, 136 are in contact respectively with the front walls of the supports 22, 26 and the formwork surfaces 16. They are thus kept tight at a distance determined by the length of the spacers.

In this situation, as shown in Figure 7, the fork 118 of the traction completely surrounds the sleeve 100. The sleeve 100 is then partially removed from the overbore 126 ensuring its guidance.

After the casting of the structure and sufficient curing of the concrete, the nuts 130 and the locknuts 132 are removed in order to release the tie rods. The latter are then extracted from the locking devices by unscrewing. In the state shown in Figure 2, the tie rod 18 can indeed be unscrewed by rotation, the two half-nuts 52, 54 together defining a conduit provided internally with a thread complementary to that of the thread of the tie rod 18. The formwork thus separated are then removed.

After dismantling the tie rods, the cylinder should be retracted for later use.

Such an arrangement allows easy adjustment of the spacing of the formwork without the need for an operator to be placed behind one of the formwork during the approximation and tightening.

In addition, it allows mounting of the tie rods by a single operator placed behind the second section 12. In fact, the locking of the tie rods takes place automatically in the unidirectional locking devices 24, 34. Furthermore, the disassembly of those -This is done by a simple manual unscrewing from the rear of the second section 12.

Claims (9)

Formwork of the type comprising two forms (10, 12) arranged substantially parallel to each other and a formwork for tightening the forms comprising at least one tie (18, 20) connecting the two forms (10, 12), the tie being immobilized in traction by a first end on a first form (10), the second form (12) comprising means (29) for axially guiding the tie rod (18, 20) in which it is free to slide, characterized in that the device for tightening the formwork (10,12) comprises a jack (38) which is arranged substantially transversely to the tie rod (18, 20), this jack comprising on the one hand, a body (39) fixed on the second form (12) and on the other part, a movable cylinder rod (40) provided at its end with a cam surface (110, 112) for actuating the tie rod (18, 20), which tie rod comprises at its second end a cam follower (104C, 106C) adapted to cooperate with said cam (110, 112) in order to cause the tightening of the two panels s (10, 12) when the actuator is actuated. Formwork according to claim 1, characterized in that the cam follower is formed from two coplanar parts (104C, 106C) arranged on either side of the axis of the tie rod and in that the cam surface is in two parts coplanar (110,112) carried by two teeth (114,116) of a fork (118) extending the cylinder rod (40), the tie being disposed between the two teeth of the fork. Formwork according to claim 1 or 2, characterized in that the cam follower (104C, 106C) is carried by a sleeve (100) traversed right through by the tie rod (18, 20) and the tie rod comprises, at its second end, a stop (130, 132) for blocking the sleeve. Formwork according to any one of the preceding claims, characterized in that the second panel (12) has a through passage (29,32) for guiding the tie rod (18,20). Formwork according to any one of the preceding claims, characterized in that the tie rod (18, 20) is a threaded rod. Formwork according to any one of the preceding claims, characterized in that the first form (10) comprises a device (24, 34) for unidirectional locking of the tie rod (18, 20) in which the first end of the tie rod is immobilized in traction. Formwork according to claims 5 and 6 taken together, characterized in that the unidirectional locking device (24, 34) comprises two half-nuts (52, 54) delimiting a threaded conduit (68) for receiving the tie rod (18, 20) and having at their end a frustoconical external chamfer (76), these two half-nuts being received free in a cage (50), the end wall facing the chamfered end of the two half-nuts (52, 54) has a central passage (64) for the tie rod (18, 20) and forms a concave seat with a conical support surface (66), the locking device further comprising an axial helical spring (56) bearing on said cage ( 50) and urging the two half-nuts (52, 54) towards the conical seat (60), the two half-nuts (52, 54) being movable between a locking position in which they form a wedge between the seat (60) and the tie rod (18, 20) when the latter is pulled out of the device, and a posit release ion in which they are released from the seat (60) and the tie rod (18) when the latter is pushed into the device. Formwork according to any one of the preceding claims, of the type comprising at least one pair of tie rods (18, 20) arranged substantially parallel and connecting the two forms (10, 12), each tie rod (18, 20) being immobilized in traction at a first end on the first branch (10), the second branch (12) comprising means (29, 32) for axial guidance of each tie (18, 20) in which each tie rod is free to slide, characterized in that the jack (38) is a double rod jack (40,42) each rod of which is provided at its end with a cam surface (110,112) adapted to cooperate with a counter cam (104C, 106C) carried by a corresponding tie rod. Formwork according to any one of the preceding claims, characterized in that the cylinder is a hydraulic cylinder.

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