EP0615817A1 - Clamping device, especially for clamping metal sheets or profiles against each other - Google Patents

Abstract

The device includes a body (1) which can be divided into two parts, a means (2) for actuating in terms of translation being mounted integrally with the body in order to actuate a mechanical linkage (5-12), the said mechanical linkage (5-12) actuating a clamping arm (14) integral with a lever. The mechanical linkage (5-12) includes a link rod (5), one end (5b) of which is guided by a first groove (8) integral with the body (1) and the other end (5a) of which is guided parallel to the direction A of displacement of the actuator (2), the said groove (8) forming an angle with the direction of displacement A of the actuator (2).

Description

The invention relates to a clamping device, in particular for the application of metal sheets or profiles against one another.

The invention is particularly useful for the assembly and automated welding of automobile bodies, a process in which collets apply body sheets against each other during welding.

Known clamping devices generally comprise a housing separable into two parts, on which is mounted at one end an actuating means in translation such as a pneumatic cylinder for actuating a mechanical coupling, said mechanical coupling successively comprising a carriage and a connecting rod to move a lever secured to a clamping arm. Such clamping devices are described in French patent 88 06176 published under the number 2 630 953, the content of which is considered to be an integral part of the present description.

Generally, the pneumatic cylinders used in these clamping devices are equipped with flow limiters, so as to obtain a substantially constant speed of movement of the cylinder, and damping systems intended to prevent any sudden impact at the end of the cylinder stroke.

• . Les limiteurs de vitesse et les systèmes d'amortissement qui limitent la vitesse de réponse du vérin constituent un empêchement à une augmentation importante des cadences.
• . Les limiteurs de débit et les systèmes d'amortissement sont des systèmes coûteux, mais surtout encombrants du fait que la place nécessaire à un vérin entièrement équipé est supérieure d'environ trente pour cent à la place nécessaire à un vérin sans équipement.

This state of the art has two drawbacks:

• . Speed limiters and damping systems that limit the speed of response of the actuator constitute an obstacle to a significant increase in rates.
• . Flow limiters and damping systems are expensive systems, but above all bulky because the space required for a fully equipped cylinder is about thirty percent greater than the space required for a cylinder without equipment.

The invention aims to create a new clamping device, in which the start and stop shocks are naturally damped, which allows the use of an actuating means without speed limitation or additional damping, such as an ordinary pneumatic cylinder of reduced dimensions.

The subject of the invention is a clamping device, in particular for the application of metal sheets or profiles one against the other, of the type comprising a body separable into two parts, a means of actuation in translation such as a cylinder being mounted integral with the body for actuating a mechanical coupling, said mechanical coupling actuating a clamping arm integral with a lever, characterized in that the mechanical coupling comprises a connecting rod, one end of which is guided by a first groove integral with the body and the other end is guided parallel to the direction of movement of the jack, said first groove forming an angle with the direction of movement of the jack.

• - l'autre extrémité de bielle est montée sur un axe guidé dans une rainure, ledit axe guidant simultanément la tige de vérin et ladite autre extrémité.
• - la première rainure est symétrique par rapport à une trajectoire moyenne, ladite trajectoire comportant un premier arc montant, un deuxième arc descendant et un troisième arc sensiblement parallèle à la direction du vérin .
• - le premier arc montant fait avec la direction de déplacement du vérin un angle compris entre 45° et 60°, de manière à obtenir une faible vitesse angulaire du bras de serrage en début ou en fin de mouvement ;
• - le deuxième arc descendant fait avec la direction de déplacement du vérin un angle inférieur à 30°, de manière à obtenir une vitesse angulaire élevée du bras de serrage en milieu de trajectoire ;
• - le troisième arc présente une courbure en rampe de forme, de manière à obtenir un ralentissement et un contact en douceur du bras de serrage avec les tôles à serrer ;
• - le deuxième arc descendant comporte une partie rectiligne faisant un angle inférieur à 30° avec la direction de déplacement du vérin, raccordée à une autre partie rectiligne faisant un angle inférieur à 10° ;
• - l'attelage mécanique comporte une biellette dont une extrémité est guidée par ladite première rainure solidaire du corps et dont l'autre extrémité est montée sur un axe solidaire du levier du bras de serrage.

According to other features of the invention

• - The other end of the connecting rod is mounted on an axis guided in a groove, said axis simultaneously guiding the jack rod and said other end.
• - The first groove is symmetrical with respect to an average trajectory, said trajectory comprising a first rising arc, a second descending arc and a third arc substantially parallel to the direction of the jack.
• - The first rising arc made with the direction of movement of the jack at an angle between 45 ° and 60 °, so as to obtain a low angular speed of the clamping arm at the start or at the end of movement;
• - The second descending arc made with the direction of movement of the jack an angle less than 30 °, so as to obtain a high angular speed of the clamping arm in the middle of the trajectory;
• - The third arc has a ramp-shaped curvature, so as to obtain a slowdown and a gentle contact of the clamping arm with the sheets to be clamped;
• - The second descending arc comprises a rectilinear part making an angle less than 30 ° with the direction of displacement of the jack, connected to another rectilinear part making an angle less than 10 °;
• - The mechanical coupling includes a link, one end of which is guided by said first groove secured to the body and the other end of which is mounted on an axis secured to the lever of the clamping arm.

• La figure 1 représente une vue en perspective avec arrachement partiel d'un mode de réalisation du dispositif selon l'invention.
• Les figures 2 à 10 représentent schématiquement le fonctionnement d'un autre mode de réalisation du dispositif selon l'invention.
• La figure 11 représente une vue schématique partielle agrandie correspondant à un mode de réalisation préférée de l'invention.

The invention will be better understood thanks to the description which follows given by way of nonlimiting example with reference to the appended drawings in which:

• FIG. 1 represents a perspective view with partial cutaway of an embodiment of the device according to the invention.
• Figures 2 to 10 schematically represent the operation of another embodiment of the device according to the invention.
• FIG. 11 represents an enlarged partial schematic view corresponding to a preferred embodiment of the invention.

Referring to Figure 1, a device according to the invention comprises a housing 1 separable into two parts assembled to form a body.

An actuating means such as a pneumatic cylinder is mounted integral and fixed relative to the base 1a of the body 1, which is itself fixedly mounted to form a clamp for clamping body sheets (not shown).

The pneumatic cylinder has a rod 2 able to move in the direction of the arrow Asous the thrust of the cylinder. Rod 2 is drilled to receive an axis prisoner 3 guided by a groove 4 when moving in the direction of arrow A.

A connecting rod 5 is coupled to the axis 3 so as to move under the thrust of the jack.

The connecting rod 5 has at one end 5a a bore corresponding to the axis 3 and at the other end 5b a bore corresponding to a guide axis 6.

The guide axis 6 carries a roller 7 which moves in a groove 8, so that the end 5b of the connecting rod moves in a movement imposed by the contour of the groove 8 forming a guide path for the roller 7.

According to the invention, the guide path 8 has a trajectory which comprises a first arc 9 which forms an angle with the direction Ade movement of the axis 6 away from the guide groove of the axis 3, then a vertex 10, a second arc 11 which forms an angle approaching the groove 4 for guiding the axis 3 and a third rectilinear arc and substantially parallel to the direction of movement A of the axis 3.

The connecting rod 5 imposes in its movement a movement on a connecting rod 12 also articulated in rotation around the axis 6 at one end 12a, while the other end 12b of the connecting rod 12 and articulated in rotation around an integral axis 13 a clamping arm 14.

In known manner, the clamping arm 14 is mounted on an axis 15 integral with the housing 1, so as to pivot in the direction of the arrow R around the axis 15 under the action of the cylinder rod 2 acting on the coupling of the connecting rod 5 and the connecting rod 12.

In known manner, the angle between the connecting rod 5 and the connecting rod 12 must always remain less than 90 °, so as to obtain a constant clamping force and to avoid any bracing effect.

• Sur la figure 2, la tige 2 du vérin est dans la position correspondant à la position de l'axe 3 à une extrémité de la rainure 4 et à l'ouverture complète du dispositif de serrage.

With reference to FIGS. 2 to 10, in which the identical reference numbers indicate elements identical or similar to those of FIGS. 1 and 2, the operation of the device according to the invention is as follows:

• In FIG. 2, the rod 2 of the jack is in the position corresponding to the position of the axis 3 at one end of the groove 4 and to the complete opening of the clamping device.

In this position, the only permissible movements of the device correspond to a thrust of the jack in the direction of arrow A, owing to the fact that the axis 3 comes to bear substantially on the end of the groove 4 and that the roller 7 also comes in abutment on the end of the groove 8, these two supports opposing any further retraction of the jack in a direction opposite to that of arrow A.

To pass from FIG. 2 to FIG. 3, the thrust of the jack in the direction of arrow A causes the advancement of the axis 3 in the groove 4 by an incrementable distance a and the progression of the roller 7 according to the rising arc 9 of trajectory which forms an angle with the direction of movement A.

The rotation R of the arm 14 around the axis 15, which corresponds to the advance of the roller 7 is low and between 9 and 12 degrees of angle. It can also be seen that the start of the movement was carried out without shock or sudden jolt, even when using a cylinder devoid of damping system or speed limiter.

Between FIG. 3 and FIG. 4, the rod of the jack 2 and the axis 3 have progressed by an additional increment a in the direction of the arrow A, so that the center of the roller 7 has slightly exceeded the top 10 of trajectory of the groove 8 and is at the start of the second arc 11 and so that the arm 14 has rotated by an additional angle between 10 and 13 degrees of angle.

By comparison with the device of the prior art described in patent 88 06 176, the rotation of the arm 14 is less according to the invention than the rotation of a corresponding device of the prior art: consequently, the start of the movement in the direction of arrow A is carried out according to the invention at a slower speed and lower rotation of the arm 14; due to the fact that this robust arm has a high inertia, it also results therefrom that the shocks at start-up are notably reduced.

Between FIG. 4 and FIG. 5, the rod of the jack 2 and the axis 3 have progressed by an additional increment a in the direction of the arrow A, so that the center of the roller 7 is substantially in the middle of the trajectory arc 11 and so that the arm 14 has rotated by an additional angle between 25 and 30 degrees of angle.

Between FIG. 5 and FIG. 6, the rod of the jack 2 and the axis 3 have progressed by an additional increment a in the direction of the arrow A, so that the center of the roller approaches the end of the trajectory arc 11, and so that the arm 14 has rotated by an additional angle of between 25 and 30 degrees of angle.

Between FIG. 6 and FIG. 7, the rod of the jack 2 and the axis 3 have progressed by an additional increment a in the direction of the arrow A, so that the center of the roller has slightly exceeded the end of the 'arc of trajectory 11 and so that the arm 15 has rotated an additional angle between 15 and 20 degrees of angle.

The center of the roller 7 is located in this position at the start of an arc 20 of trajectory which is not cross-line as in the case of FIG. 1, but which has a curvature similar to the curvature of the ramp of shape described in French patent 88 06176, the function and shape of which were determined to avoid any bracing effect and to obtain a large clamping range compatible with long-term use despite the wear of the moving parts and corresponding guide paths.

Compared with the prior art, the rotation of the arm between FIGS. 5 and 7 appears to be effected at much higher speed, which corresponds to an apparent acceleration.

Between FIG. 7 and FIG. 8, the rod of the jack 2 and the axis 3 have progressed by an additional increment a in the direction of the arrow A.

In the position of FIG. 8, the center of the roller 7 is located at the start of the shaped ramp corresponding to the contact of the arm 15 with sheets not shown.

The rotation of the arm 15 between Figures 7 and 8 is between 5 and 8 degrees of angle, which corresponds to an apparent deceleration compared to the previous phase.

According to the invention, the use of the ramp of known shape to avoid bracing thus leads to an additional deceleration and to a "soft landing" on the sheets to be clamped.

Between FIG. 8 and FIG. 9, the jack rod 2 and the axis 3 have progressed by a distance corresponding to the tightening of the sheets, at a position of the roller center 7 located substantially in the middle of the arc 20 corresponding to the shape ramp and an additional rotation of the arm 14 less than two degrees of angle corresponding to the taking up of the mechanical clearances during the application of the clamping force coming from the jack rod 2 and transmitted by the link rod 5 - link 12 to the clamping arm 15.

Figure 10 corresponds to a clamping position corresponding to the maximum allowable wear of the device: between Figure 8 and Figure 10, the cylinder rod 2 and the axis 3 have advanced by a distance t corresponding to the total stroke tightening the device; the roller 7 is in abutment on the end of the groove 8 and the clamping arm 14 has rotated by an additional angle relative to FIG. 8, of value less than 4 degrees of angle.

• . Dans une première phase de déplacement dans le sens de la flèche A, correspondant à un arc "montant" 9 de trajectoire, le bras de serrage 15 présentant une inertie important tourne à vitesse angulaire plus faible dans le sens de la flèche R.
• . Dans une deuxième phase de déplacement dans le sens de la flèche A correspondant à un arc "descendant" 10 de trajectoire, le bras de serrage 15 présentant une inertie importante tourne à vitesse angulaire plus rapide dans le sens de la flèche R.
• . Dans une troisième phase de déplacement dans le sens de la flèche A correspondant à un arc 20 de direction sensiblement parallèle à la flèche A, le bras de serrage 15 ralentit pourve- nir au contact des tôles à serrer, en douceur et sans chocs.

The invention provides the following advantages over the prior art, in which a carriage moving at the same speed as that of the jack produced a uniform movement of a clamping arm:

• . In a first phase of movement in the direction of arrow A, corresponding to a "rising" arc 9 of trajectory, the clamping arm 15 having a high inertia rotates at lower angular speed in the direction of arrow R.
• . In a second phase of movement in the direction of arrow A corresponding to a "descending" arc 10 of trajectory, the clamping arm 15 having a high inertia rotates at faster angular speed in the direction of arrow R.
• . In a third phase of movement in the direction of arrow A corresponding to an arc 20 of direction substantially parallel to arrow A, the clamping arm 15 slows down to come into contact with the sheets to be clamped, smoothly and without shocks.

In particular, when the arc 20 corresponds to a ramp of known shape to avoid the device bracing, there is obtained an unforeseen dynamic effect of slowing down when approaching the sheets: this technical effect results in part from the change in curvature between the arc 11 and the arc 20, and in particular of the inversion of curvature.

Due to the reversibility of the movements, the advantages of the invention are obtained whatever the direction of movement of the jack rod 2.

With reference to FIG. 11, a preferred embodiment of guide groove 8 according to the invention has a constant width and is substantially symmetrical around a mean trajectory having a first rising arc 9, a vertex 10, a second descending arc 11 and a third arc 20.

The rising arc 9 has a straight end 9a which forms with the direction of movement A an angle 16 of between 45 ° and 60 ° and an end 9b in the form of an arc of a circle corresponding to the roller 7.

The descending arc 11 comprises, from the apex 10, a circular arc 11a has the same curvature as the circular arc 9b, then a rectilinear segment 11 b forming with the direction of movement A an angle 17 less than 30 ° , then a second rectilinear segment 11 c making with the direction of movement an angle 18 less than 10 degrees.

The arc 20 corresponding to the shape ramp is connected at 19 to the second rectilinear segment 11c, the point 19 corresponding to an inversion of curvature with respect to the general shape of the descending arc 11.

The ends of the average trajectory corresponding to semi-cylindrical end machining operations correspond to the stopping and disengagement of the milling cutter machining the groove 8, and to the external shape of the roller 7 intended to be guided by the groove 8.

The invention set out in relation to a particular embodiment, but on the contrary covers any modification of shape and any variant of execution within the scope and spirit of the invention: in particular, the invention also covers devices mechanically equivalents in which a roller-guide groove assembly is replaced by a groove-guide roller assembly; the slow, fast and slow phases of the angular movement of the clamping arm 14 being retained in the kinematic transposition.

The invention covers in particular devices of the kind comprising a pivoting, articulated or similar connection between an actuator of any kind (cable, electric motor, mechanical jack driving a ball screw, etc.) in place of a connection fixed of the particular embodiment described above.

Claims (8)

1. - Clamping device, in particular for the application of metal sheets or profiles against one another, of the type comprising a body separable into two parts, a means of actuation in translation being mounted integral with the body for actuating a mechanical coupling, said mechanical coupling actuating a clamping arm integral with a lever, characterized in that the mechanical coupling (5-12) comprises a connecting rod, one end (5b) of which is guided by a first groove (8) integral with the body (1) and the other end (5a) is guided parallel to the direction (A) of movement of the jack (2) said first groove (8) forming an angle (16) with the direction of movement (A) of the jack (2). 2. - Device according to claim 1, characterized in that the other end (5a) of connecting rod is mounted on an axis (3) guided in a groove (4), said axis (3) simultaneously guiding the rod (2) cylinder and said other end (5a). 3. - Device according to one of claims 1 or 2, characterized in that the first groove (8) is symmetrical with respect to an average trajectory, said trajectory comprising a first rising arc (9), a second descending arc (10 ) and a third arc (20) substantially parallel to the direction of the jack. 4. - Device according to claim 3, characterized in that the first rising arc (9) made with the direction of movement (A) of the jack (2) an angle (16) between 45 ° and 60 °, so as to obtain a low angular speed of the clamping arm (14) at the start or end of movement. 5. - Device according to claim 3, characterized in that the second descending arc (11) made with the direction of movement (A) of the jack (2) an angle (17) less than 30 °, so as to obtain a speed high angle of the clamping arm (14) in the middle of the trajectory. 6. - Device according to claim 3, characterized in that the third arc (20) has a curved ramp shape, so as to obtain a deceleration and a gentle contact of the clamping arm (14) with the sheets to be clamped . 7. - Device according to one of claims 3 to 6, characterized in that the second descending arc (11) comprises a rectilinear part (11a) making an angle less than 30 ° with the direction of movement (A) of the jack (2 ), connected to another rectilinear part making an angle less than 10 °. 8. - Device according to one of the preceding claims, characterized in that the mechanical coupling comprises a link (12), one end (12a) of which is guided by said first groove (8) secured to the body (1) and of which l the other end (12b) is mounted on an axis (13) integral with the lever of the clamping arm (14).

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