CLAMPJOINT FOR CONCRETE PILES

Description

[0001] The object of the invention is a stiff adjoint piece for joining concrete piles, particularly reinforced piles, end to end so that those ends of the concrete piles which are joined together comprise base plates that correspond to the cross-section of the pile, the joining means being attached to the base plate and consisting of: projecting locking bars which comprise broad ends provided with at least one stop face pointing towards the said base plate; of locking blocks on the counterpart, provided with a cavity that receives the locking bar, and with a groove transversal to the length of the locking bars, the groove extending as a toroid around the cavity, and with a hole extending from this groove at least approximately in a tangential direction; and of an insert pin which, when the pile joint is made, is driven into the hole so that it rums around the locking bar in the cavity, guided by the circumferential face of the groove, whereby it is simultaneously locked permanently in place because of plastical deformation.

[0002] In Finland and other parts of the world, long concrete piles are provided with adjoint pieces to facilitate handling and transportation.

[0003] An adjoint piece of the type defined above is described in publication FI-76169, and slightly similar joints are described in publications FI-57293 and FI-58669. All these joints employ fork-like locking means in which only very minor locking deformation takes place when they are put in place. These pile joints which are known from before and which are used for the corresponding purpose have numerous disadvantages. First, the structure of the known joints is complex and expensive to implement, or unreliable in use because the joint tends to open under the effect of concussions that occur when the pile is driven to the ground. Consequently, material costs have been great in the constructions used earlier. Furthermore, clampjoints in these earlier constructions had to be welded to the base plate by using load-bearing seams, whereby it was necessary to use thick base plates because of thermal strain. The disengagement or loosening of the joint during driving down again caused all kinds of other problems and, thus, different costs.

[0004] The former patent application FI-852020 of the applicant tried to solve the above-mentioned problem by using a long insert pin which was bent into a doughnut-shaped channel which was jointly formed by the groove of the locking block and the groove of the locking bar opposite the former. Such a pile joint is good because of its great length of deformation which prevents it from opening under any conditions. Because, in publication FI-852020, the joint is implemented by opposite grooves, i.e., by clamping in the direction of the toroid radius, its structure, however, has the same problem as the structures of the other publications mentioned above. All these known structures require that the base plate of the pile be carefully machined into a planar form of an accurate thickness because, otherwise, the joint will either be loose or the insert pin will possibly not go into its place. Disregarding the machining, the welding of the sheet casing of the pile end box to the base plate can cause deformation in the base plate with the consequences described above.

[0005] The object of the invention is to provide a simpler, stiff adjoint piece for reinforced piles which does not have the disadvantages of the earlier known, corresponding joints. A more detailed object of the invention is to provide a stiff joint with low material costs which can be manufactured with low labour costs. Another object of the invention is to provide a pile joint with clamping which will not become loose even after a great number of strikes. Another object of the invention is to provide a pile joint solution with clamping means to which reinforcement bars can be attached by threading or welding. Another object of the invention is to provide a pile joint solution which simply provides a tight mutual joint for the piles.

[0006] The disadvantages of the known structures can be eliminated and the objects of the invention defined above can be accomplished by a pile joint which is characterised by what is defined in the characterising clause of Claim 1.

[0007] The pile joint according to the invention can be used to obtain numerous advantages. Because of the simple construction, considerable savings are obtained in material and labour costs. A clampjoint is obtained which does not become loose even after a lot of striking because a very large locking deformation is created in the insert pin when it is installed in place. This construction also prevents disadvantages caused by water which freezes in the lock housing on the pile-driving site when the joint is made. In addition, a clampjoint is provided which creates a tight joint between the piles, both in a case where the locking block is attached to the inner face of the end part, and particularly in a case where the locking block forms a stop face or a part of it for the joint.

[0008] The invention is described in detail with reference to the appended drawings.

[0009] Fig. 1 is a general top view of the end of a reinforced concrete pile provided with the joint members according to the invention, taken in direction I of Figs. 2 and 3, and as a partly cut view along plane II-II of Figs. 2 and 3.

[0010] Fig. 2 presents a detailed view of the members providing the joint according to the invention as a longitudinal section of the pile along plane III-III of Fig. 1, as the second embodiment thereof.

[0011] Fig. 3 presents the embodiment according to Fig. 2 as an otherwise similar but smaller view than in Fig. 2 with the ends of the pile apart.

[0012] In Figs. 1, 2, and 3, the pile joint according to the invention is generally marked reference number 1. Mutually similar joint bisegments 1a and 1b form a double joint placed end to end, thus forming the joint between the joint ends of the piles. Joint sections 1a and 1b is made from thick enough steel plate and of locking parts in the manner described below. Generally, each joint bisegment comprises the same amount of female joint parts and male joint parts placed symmetrically so that two pile ends provided with similar joint bisegments are placed tightly against one another. Fig. 1 shows one such embodiment comprising female joint parts in two opposite comers and male joint parts in the two other opposite corners. Other arrangements can also be used.

[0013] The end of the pile comprises, in a conventional way per se, base plate 5 with the same cross-sectional shape as the pile, for example square, from which margin collar 7 on the level of the pile outer surface generally projects to the side of the pile, whereby a box-like part is formed, covering the end of the pile, and base plate 5 constituting the end face of the pile. Furthermore, the pile comprises, inside the concrete, at least longitudinal reinforcement bars or starter bars 6.

[0014] The structure described above contains male locking bars 2 extending from base plate 5, female locking blocks 3 and insert pins 4 inside the end of the reinforced pile, according to the invention. Fig. 2 presents an embodiment comprising base plate 5 which is provided with holes 10 through which locking bars 2 and particularly their wide outer ends 20 can be accommodated. Locking block 3 is provided with a hole or cavity 9 through which locking bar 2 can go. Starter bars 6 in the longitudinal direction of the pile are attached directly to locking blocks 3 by welding or threading. Correspondingly, locking bars 2 run through the holes in the base plate and are attached directly to starter bars 6 by welding or threading. In addition, the locking blocks and the locking bars are generally also welded to the base plate, as shown in the figures.

[0015] According to the invention, locking block 3 is provided with groove 8 that surrounds the entire cavity 9 in a toroid-like way on the circumferential face of the cavity, the circumference of the groove being transversal and typically perpendicular to the length of the locking bar and thus to the length of the pile. According to all the embodiments of the invention, this groove comprises annular stop face 24 which points away from end plate 5 of said joint bisegment 1b, i.e., towards the interior of the pile. The stop face is preferably planar and typically perpendicular to length L of the pile. Locking bar 2 is preferably provided with groove 11 that is transversal to the length of the pin and thus to the length of the pile, the groove comprising annular stop face 21 which points towards the base plate to which locking bar 2 is attached. Upon the locking bar penetrating into cavity 9 when joint 1 is assembled, grooves 8 and. 11 are placed against one another, forming a circumferential channel that surrounds locking bar 2, the cross-sectional shape of the channel corresponding to the cross-sectional shape of insert pin 4. According to the invention in particular, the cross-section of the insrt pin and the diameter and location of grooves 8 and 11 are dimensioned so that the insert pin is tightly placed, in grooves 8, 11, distinctly between stop face 24 of locking block 3 and stop face 21 of locking bar 2. In this way, when driven inside the grooves, insert pin 4 clamps joint bisegments 1a and 1b of the piles to be joined towards one another, forming a tight pile joint 1 without clearance. The other surfaces of grooves 8 and 11 are only significant in shaping the locking pin when it is driven in place when the joint is made. This design provides a tight and accurate guiding for insert pin 4 and, thus, a strong joint between the ends of the piles. In locking bar 2, it is also possible to only use its head 20 which is wider than its arm and which comprises the said stop face 21; this embodiment not being shown in the figures, whereby the insert pin penetrates into the circumferential channel formed by groove 8 of the locking block and stop face 21, as described above. However, this structure is not quite as reliable as the one formed by aligned grooves 8, 11.

[0016] Furthermore, each locking block 3 comprises hole 12 which extends from groove 8 essentially in the tangential direction to the outer face of the pile or to the outer face formed by sheet casing 7. This hole is preferably lined, for example, with metal tube 13 with respect to the concrete. Insert pins 4 according to the invention are long or bar-like parts which are straight before installing in place. The length of the insert pin is at least as high as depth H of the hole and the essential part of the circumferential length of the locking block groove 8 together; typically, the length of the insert pin is as high as the depth of the hole and half of the said circumferential length together. The length of the insert pin is preferably as close as possible to the sum of the hole depth and the said circumferential length. The cross-sectional shape of insert pin 4 remains, at least with respect to the essential part of its length, unchanging or integral, starting from initial end 22 of the insert pin which is pushed ahead through hole 12 to groove 8. The cross-section of the insert pin is preferably unchanging along the portion of its length that corresponds to the length that bends in accordance with groove 8. For example, if the insert pin is so long that it bends and fills the entire circumferential length of groove 8, the cross-section of the pin is mainly unchanging along the length which is as long as the circumferential length. The cross-sectional shape and/or the cross-sectional area of the insert pin can vary to the extent of hole 12, i.e., starting from the other ram end; the pin is preferably thicker along this length. In this case, the insert pin better withstands the push exerted on the ram end which is used to place the pin in the channel. The cross-section of insert pin 4 is round, angular, or oval. The cross-section of insert pin 4 is preferably rectangular, whereby it comprises parallel, opposite surfaces 28a and 28b which are placed against said stop faces 21 and 24. The invention does not prevent the insert pin from being slightly sphenoid in the longitudinal direction, whereby the pin penetrates easier into its place and clamps the pile ends towards one another. In this case also, the cross-section remains unchanged. According to the invention, this wedge-sized property is arranged to be formed between opposite surfaces 28a and 28b of the insert pin, whereby the wedge-sized property is placed between stop face 24 of the locking block and stop face 21 of the insert pin. Generally, the wedge-sized property extends approximately evenly along the entire length of the insert pin which is bent into a toroid and is small in quantity, for example, the angle of wedge between surfaces 28a and 28b is about 10° at the most, generally even smaller, such as less than 5°, possibly only 3° - 4° or 1° - 2°. Generally, there is no wedge-sized property in insert pins 4 in the direction of the toroid diameter formed by grooves 8, 11, and thus of the plane of base plate 5, but the insert pins have even widths on the above-mentioned length, because the wedge-sized property is not advantageous here. The wedge-sized property is thus not the same as rounding or bevelling of the end of insert pin 4, which guide and facilitate the penetration of the insert pin into the grooves and which are presented in Fig. 1. In this way, the insert pin can be used to provide the joint described below.

[0017] Piles are extended by pushing the piles provided with the above-mentioned joining parts together end to end, whereby locking bars 2 penetrate from locking blocks 9. With base plates 5 of pile joints 1 squeezing tightly together and, in the embodiments of Figs. 2 and 3, front surfaces 26 of locking blocks 3 squeezing tightly against outer surface 27a of base plate 5 of the opposite joint bisegment 1a, the joint is clamped by driving insert pins.4 according to the invention into each clampjoint which is comprised of a locking bar and locking blocks. When insert pin 4 is pushed in place in the direction of arrow 19 in Fig. 1, it is shaped according to the channel formed by grooves 8 and 11, particularly guided by the circumferential face of groove 8 in the locking block, into an annular strap around locking bar 2, as shown by the line of dots and dashes in the upper right hand corner in Fig. 1. As already described above, the larger the part of the circumferential length of the circumferential or toroidal channel is filled by the locking bar, the more advantageous it is. In any case, the locking bar should fill- an essential part of the circumferential length surrounding locking bar 2, whereby half of the circumferential length can be considered minimum. At the same time, insert pin 4 locks joint bisegments 1a and 1b together at said stop faces 21 and 24 in a phenoidal way, and, because of the large plastical deformation, it is locked into the joint without becoming loose, whereby the joint stays good even after numerous strokes.

[0018] Figs. 2 and 3 present a particularly preferred embodiment of the invention. It comprises holes 25 made for locking blocks 3 in base plate 5, the diameter of the holes being so dimensioned that the locking block fits through the base plate at least at the end part which points outwards from this joint bisegment 1b. The locking block is welded to the base plate at a spot where front surface 26 of the locking block is flushed with outer surface 27b of the base plate. In this solution, it is not necessary to use a machined plate as the base plate of either joint bisegment 1a and/or 1b but, generally, a piece cut from a plate can be used as such. In this case, the thickness of the base plate has no significance because distance T2 between stop face 24 of locking block 3 and front surface 26, and distance T1 between stop face 21 of the locking bar and shoulder 29 define the position of the stop faces in joint 1, no matter what the thickness of base plate 5 is. Consequently, it is necessary to accurately machine only locking blocks 3 and locking bars 2 in this structure. The good clamping accuracy of joint 1 mentioned earlier can be provided by this structure in a simple and advantageous manner. Distinguished from this, a shoulder which is not presented in the figures can be provided on the outer circumference of the locking block, pressing against the above-mentioned inner surface 21 of the base plate. In this case, front surface 26 of the locking block can be arranged at such a distance from this shoulder that it is always placed at least level with outer surface 27b of the base plate or so that it slightly projects therefrom. Alternatively, base plate 5 and a slightly too long locking block 3 attached thereto can be machined from the outside, after the weldings, to form an integral surface 26, 27b, whereby the spot of welding is controlled from stop face 24. This requires machining but less than in prior art solutions, and the accuracy is very good because welding can no longer influence the accuracy.

[0019] The embodiment described above is only one advantageous embodiment of the invention and those skilled in the art understand that numerous modifications can be made thereto without deviating from the scope of the invention. For example, the insert pin can be a self-locking, annular spring. Similarly, the grooves of the locking means can have a rectangular cross-section, they can be shaped like parts of a polygon or they can be round or V-shaped and their longitudinal section can be straight or V-shaped. The insert pins have the same or slightly modified cross-section and/or longitudinal section so that a desired clamping and plastical deformation are achieved. Thus, the scope of the invention is defined within the inventive idea described in the appended claims.

Claims

1. A stiff joint for joining concrete piles end to end, in which each end of the concrete pile that comes to the joint is provided with a base plate (5) that corresponds to the cross-section of the pile and joining members being attached to the base plate, said joining members comprising:

- projecting locking bars (2), welded to said base plate, having a wide head (20) which comprises at least one stop face (21) that points towards the said base plate;

- locking blocks (3), welded to said base plate, on the counterpart which are provided with a cavity (9) for receiving said locking bar (2), and with a groove (8) transversal to the length of the locking bar, the groove extending toroid-like around said cavity (9), and with a hole (12) that extends from this groove at least approximately tangentially; and

- an insert pin (4) with a cross-section which has a same form at least throughout a part of its length, and said pin is driven trough the hole when the pile joint is made so that it is curved around the locking bar (2) in said cavity, guided by the circumferential surface of the groove (8), whereby it is locked permanently in place by plastic deformation effect,

characterised in that:

- said locking block (3) extends through a hole (25) in the base plate (5), the front surface (26) of the locking block is essentially flush with the outer surface (27b) of the base plate (5), and said locking block (3) comprises a stop face (24) in said groove pointing away from said end plate; that

- said stop faces (21 and 24) have a position transversal to the length (L) of the pile; and that

- the cross-section of the insert pin (4) remains at least approximately unchanged throughout a part of its length corresponding the curvature length inside said groove (8), whereby the insert pin clamps the parts of the pile joint together while penetrating to the groove (8) between the stop face (21) of the locking bar (2) and the stop face (24) of the locking block (3).

2. A joint according to Claim 1, characterised in that the locking bar comprises a groove (11) that contains a stop face (21), whereby the insert pin (4) is curved along a channel formed by said grooves (8) and (11) which are against one another, that the gap between the locking block (3) and the outer surface of the pile or a sheet casing (7) that forms this outer surface comprise a guide tube (13) for the insert pin (4), and that said stop face (24) of the locking bar (2) and said stop face (21) of the locking block (3) in the joint (1) are essentially parallel.

3. A joint according to Claim 1 or 2, characterised in that the length of the insert pins (4) is at least as long as the depth (H) of the hole and the essential part of the circumferential length of the groove (8) of the locking block together, typically the length of the insert pin is as long as the depth of the hole and half of the said circumferential length together, and preferably the length of the insert pin is as close as possible to the sum of the depth of the hole and the said circumferential length, whereby the insert pin (4) is curving, when driven in, to an annular form, along the length of the essential part of the circumferential length of the locking bar.

4. A joint according to any of the preceding Claims, characterised in that the cross-section of the insert pin (4) is round, oval or angular, or preferably rectangular, and that the opposite surfaces (28a and 28b) of the insert pin which are placed against said stop faces (21, 24) are either parallel or they constitute a wedge angle with respect to one another in the longitudinal direction of said insert pin.

Ansprüche

1. Ein steifes Verbindungsstück zur Verbindung von Betonsäulen Stoß auf Stoß, wobei jedes Ende der Betonsäulen, das zum Verbindungsstück hinweist, mit einer Basisplatte (5) ausgestattet ist, die dem Querschnitt der Säule entspricht und Verbindungsmittel, die auf der Basisplatte befestigt sind, wobei die besagten Verbindungsmittel Folgendes umfassen:

- vorstehende Schließzylinder (2), welcher mit der Basisplatte verschweißt sind und einen flächigen Kopf (20) aufweisen, der wenigstens eine Anschlagsfläche (21) umfasst, die in Richtung der besagten Basisplatte weist;

- an der besagten Basisplatte des Gegenstücks angeschweißte Verriegelungsblöcke (3), welche eine Kavität (9) zur Aufnahme des besagten Schließzylinders (2) bereitstellen und eine Nut (8) transversal zur Längsrichtung der Schließzylinder aufweisen, wobei sich die Nut sich toroidförmig um die Kavität (9) erstreckt und welche ein Loch (12) aufweisen, das sich wenigstens annähernd tangential zu dieser Nut erstreckt; und

- ein Sicherungsstift (4), der den gleichen Querschnitt über wenigstens einen Teilbereich seiner Länge aufweist, wobei der besagte Stift durch das Loch getrieben wird, wenn die Säulenverbindung erstellt ist, so dass er sich um den Schließzylinder (2) in der besagten Kavität windet, geführt durch die Umfangsfläche der Nut (8), wobei er aufgrund der plastischen Verformung in dieser Stellung verankert wird,

   dadurch gekennzeichnet, dass:

- sich der besagte Verriegelungsblock (3) durch ein Loch (25) in der Basisplatte (5) erstreckt, wobei die Frontfläche (26) des Verriegelungsblocks im Wesentlichen mit der Außenfläche (27b) der Basisplatte (5) eben abschließt und der besagte Verriegelungsblock (3) eine Anschlagsfläche (24) in der besagten Nut umfasst, welche von der besagten Abschlussplatte wegweist;

- die besagten Anschlagsflächen (21 und 24) transversal zur Längsrichtung (L) der Säule ausgerichtet sind; und

- der Querschnitt des Sicherungsstifts (4) wenigstens annähernd in einem Teilbereich seiner Längsausdehnung unverändert bleibt, die der Bogenlänge im Inneren der Nut (8) entspricht, wobei der Sicherungsstift die Teile der Säulenverbindung zusammenklemmt, während er in die Nut (8) zwischen der Anschlagsfläche (21) und dem Schließzylinder (2) und der Anschlagsfläche (24) des Verriegelungsblocks (3) eindringt.

2. Ein Verbindungsstück gemäß Anspruch 1, dadurch gekennzeichnet, dass der Schließzylinder eine Nut (11) umfasst, die eine Anschlagsfläche (21) aufweist, wobei der Sicherungsstift (4) entlang eines Kanals gebogen wird, der aus den besagten zueinander ausgerichteten Nuten (8) und (11) gebildet wird; dass im Bereich zwischen Verriegelungsblock (3) und der Außenfläche der Säule oder der Ummantelung (7), die diese Außenfläche bildet, eine Führungsröhre (13) für den Sicherungsstift (4) ausgebildet ist, und dass die besagte Anschlagsfläche (24) des Schließzylinders (2) und die besagte Anschlagsfläche (21) des Verriegelungsblocks (3) im Verriegelungsstück (1) im Wesentlichen parallel sind.

3. Ein Verbindungsstück gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Länge der Sicherungsstifte (4) wenigstens so lang wie die Summe aus der Lochtiefe (H) und einem wesentlichen Teil der Umfangslänge der Nut (8) im Schließzylinder ist; typischer Weise ist die Länge des Sicherungsstifts so lang wie die Summe aus der Lochtiefe und der halben besagten Umfangslänge und bevorzugt ist eine Länge des Sicherungsstifts, die der Summe aus der Lochtiefe und der besagten Umfangslänge möglichst nahe kommt, wobei der Sicherungsstift (4) beim Hineintreiben in eine kreisringförmige Form, entlang der Verlaufsrichtung des wesentlichen Teils der Umfangslänge im Schließzylinder, gebogen wird.

4. Ein Verbindungsstück gemäß einem der voranstehenden Ansprüche, dadurch gekennzeichnet, dass der Querschnitt des Sicherungsstifts (4) rund, oval oder eckig oder bevorzugt rechteckig ausgebildet ist, und dass die gegenüberliegenden Flächen (28a und 28b) des Sicherungsstifts, die an den besagten Anschlagsflächen (21, 24) anliegen, entweder parallel sind oder einen Keilwinkel zueinander ausbilden, der sich in Längsrichtung des besagten Sicherungsstifts erstreckt.

Revendications

1. Joint rigide de raccordement bout à bout de pieux de béton, dans lequel chaque extrémité de pieu de béton qui participe au joint possède une plaque de base (5) qui correspond à la section du pieu et des organes de raccordement qui sont fixés à la plaque de base, les organes de raccordement comprenant :

des barres de blocage (2) en saillie, soudées à la plaque de base, ayant une tête large (20) qui comporte au moins une face d'arrêt (21) tournée vers la plaque de base,

des blocs de blocage (3), soudés à la plaque de base, sur la partie antagonoste desquels est disposée une cavité (9) de logement de la barre de blocage (2) et d'une gorge (8) transversale à la longueur de la barre de blocage, la gorge s'étendant sons forme toroldale autour de la cavité (9), et avec un trou (12) qui s'étend depuis cette gorge au moins approximativement en direction tangente, et

une broche d'insertion (4) de section de même forme au moins sur toute une partie de sa longueur, la broche étant introduite dans le trou lorsque le joint du pieu est réalisé afin qu'elle soit courbée autour de la barre de blocage (2) dans la cavité, en étant guidée par la surface circonférentielle de la gorge (8), si bien qu'elle est bloquée de façon permanente en position par un effet de déformation plastique,

   caractérisé en ce que
   le bloc de blocage (3) s'étend dans un trou (25) formé dans la plaque de base (5), la surface avant (26) du bloc de blocage est pratiquement au niveau de la surface externe (27b) de la plaque de base (5), et le bloc de blocage (3) comporte une face d'arrêt (24) dans la gorge du côté opposé à la plaque de base, en ce que
   les faces d'arrêt (21 et 24) ont une position transversale à la longueur (L) du pieu, et en ce que
   la section de la broche d'insertion (4) reste au moins approximativement inchangée sur une partie de sa longueur qui correspond à la longueur de partie courbe à l'intérieur de la gorge (8), si bien que la broche d'insertion serre les parties du joint de pieu en coopération tout en pénétrant dans la gorge (8) entre la face d'arrêt (21) de la barre de blocage (2) et la face d'arrêt (24) du bloc de blocage (3).

2. Joint selon la revendication 1, caractérisé en ce que la barre de blocage comporte une gorge (11) qui contient une face d'arrêt (21), si bien que la broche d'insertion (4) est courbée le long d'un canal formé par les gorges (8) et (11) qui sont placées l'une en face de l'autre, en ce que l'espace compris entre le bloc de blocage (3) et la surface externe du pieu ou d'une enveloppe en feuille (7) qui forme cette surface externe comporte un tube de guidage (13) de la broche d'insertion (4), et en ce que la face d'arrêt (24) de la barre de blocage (2) et la face d'arrêt (21) du bloc de blocage (3) dans le joint (1) sont essentiellement parallèles.

3. Joint selon la revendication 1 ou 2, caractérisé en ce que la longueur des broches d'insertion (4) est au moins égale à la profondeur (H) du trou et de la partie essentielle de la longueur circonférentielle de la gorge (8) du bloc de blocage ensemble, habituellement la longueur de la broche d'insertion est aussi longue que la profondeur du trou et la moitié de la longueur circonférentielle considérées ensemble et de préférence la longueur de la broche d'insertion est aussi proche que possible de la somme de la profondeur du trou et de la longueur circonférentielle, si bien que la broche d'insertion (4) se courbe, lorsqu'elle est introduite à l'intérieur, à une forme annulaire, le long de la partie essentielle de la longueur circonférentielle de la barre de blocage.

4. Joint selon l'une quelconque des revendications précédentes, caractérisé en ce que la section de la broche d'insertion (4) est circulaire, ovale ou angulaire ou de préférence rectangulaire, et en ce que les surfaces opposées (28a et 28b) de la broche d'insertion qui sont placées contre les faces d'arrêt (21, 24) soit sont parallèles, soit constituent un angle de coin l'une avec l'autre dans la direction longitudinale de la broche d'insertion.

Drawing