FR2754484A1 - IMPROVEMENT FOR A TIGHTENING DEVICE OF THE TYPE INCLUDING A PISTON-OPERATED LEVER - Google Patents

Abstract

Clamping device for retaining a construction part to be machined or welded, of the type comprising a lever (2) mounted to pivot about an axis of rotation with respect to a device body (4) to be actuated in pivoting by the displacement of the piston of a cylinder with a longitudinal axis between a first position called the inactive release position, and a second position called the active clamping position, said lever (2) being connected to the end (8) of the piston rod (6) by means of control and connection means characterized in that it comprises means for transmitting the force intended to allow obtaining a significant clamping force of the lever (2) which is substantially constant during that said lever pivots between an attack position (C) remote from the clamping position (B) and a position close to the clamping position (B) of the lever.

Description

IMPROVEMENT FOR TYPE TIGHTENING DEVICE

  INCLUDING A PISTON-DRIVEN LEVER

  The present invention relates to a clamping device comprising a lever actuated hydraulically or pneumatically by a piston of the type used to hold workpieces

or solder.

  In the industrial field, it is necessary to retain the parts so that, for example, they can be machined or assembled by welding. Of course, various devices are used, such as, for example, clamps or sleeper systems, operated manually, which have a number of drawbacks. Also, manufacturers have developed automatic clamping systems, which include at least one lever actuated from an inactive release position to an active clamping position and vice versa, by the displacement of a piston which can be controlled pneumatically or hydraulically. . There are many known clamping devices of the type comprising a jack controlling the pivoting of a lever arm by means of a connecting rod or of several rods, in particular the clamping devices described by patent applications.

  French published under the numbers 2 340 798 or 2 536 323.

  In all of these documents, the clamping devices described have the drawback of having a clamping force exerted by the lever during its passage from the inactive release position to the active clamping position which does not reach values satisfactory that when said lever is in a position located in the vicinity very close to its active clamping position, the clamping force having relatively low values during the majority of the passage between the

two positions.

  In addition, the various devices described are generally heavy, complicated and often have openings allowing chips, dirt or weld spatter to get inside the device, thus preventing the proper functioning of the mechanism. The object of the present invention is to remedy the drawbacks presented by current devices by simple and reliable means allowing the clamping device to present a clamping force.

  satisfactory while providing a seal against various soils.

  Thus, according to the main characteristic of the invention, the clamping device intended to hold a construction part to be machined or welded is of the type comprising a lever mounted pivoting about an axis of rotation relative to a device body to be pivotally actuated by the displacement of the piston of a jack between a first position called the inactive release position, and a second position called the active clamping position, said lever being connected to the end of the piston rod by means of control and connection means, and comprises force transmission means intended to allow the obtaining of a large and substantially constant lever clamping force while said lever pivots between an attack position distant from the position tightening and a position close to the position

lever tightening.

  According to an additional characteristic, the control and connection means comprise at least one connecting rod pivotally mounted, on the one hand on the clamping lever around a secondary pivot axis, and on the other hand either on a member of said control and connection means either directly on the piston rod around a main pivot axis, the force transmission means being constituted by guide means intended to guide the main pivot axis in a trajectory at less inclined in part

  relative to the longitudinal axis of the cylinder.

  According to one embodiment of the invention, the connecting rod is pivotally mounted at one of its ends around a main pivot axis on an intermediate piece movable in translation of the control and connecting means, said piece being carried by the end of the piston rod and at the other of its ends around a secondary pivot axis on the mounting part or the arm of the clamping lever. According to an additional characteristic, the guide means comprise inclined guide means constituted by inclined ramps intended to guide end rollers disposed on the main pivot axis along a path at least partially inclined

  relative to the longitudinal axis of the cylinder.

  According to another characteristic, the guide means consist of blind guide lights located on the internal faces of the side walls of the body of the device, said lights comprising vertical rectilinear ramps extended by the ramps

inclined.

  In addition, according to one embodiment, the inclined ramps are located above the horizontal plane which contains the axis of rotation of the lever. According to a variant, the guide means comprise inclined guide means constituted by inclined ramps at least

partly curved.

  According to an additional characteristic, the inclined ramps are inclined upwards and towards the lever with respect to the longitudinal axis of the jack in a median plane of general symmetry of the device.

Tightening.

  According to another characteristic, the distance between the main pivot axis and the secondary pivot axis carried by the connecting rod is less than the orthogonal distance between the axis

  longitudinal of the cylinder and the axis of rotation of the clamping lever.

  In addition, according to one embodiment, the inclined ramps are curved so that the angle formed between the longitudinal axis of the connecting rod and the straight line perpendicular to the tangent to the curvature of the inclined ramp at said point o is located the roller is substantially constant when said end rollers run through said ramps between an attack position and a position close to an intermediate clamping position. In addition, the clamping device may comprise a protection member integral in rotation with the lever which comprises a circular upper wall and two lateral cheeks, the

  protection can be made of aluminum.

  According to an additional characteristic, the clamping device

has a detection system.

  Other characteristics and advantages of the invention will emerge

  of the description which will follow with regard to the appended drawings which are not

  given only by way of nonlimiting examples.

  Figures 1 to 9 illustrate a particular embodiment of the

  clamping device according to the invention.

  Figure 1 shows the clamping device and the cylinder in view

  lateral exterior in the inactive release position.

  Figure 2 shows said device in external side view

in its clamping position.

  Figure 2a shows the device in its clamping position in side view along F. Figure 2b shows the device in its clamping position in

top view.

  Figures 3a, 3b and 3c illustrate in longitudinal section in a median plane different positions of the clamping, Figures 3'b and 3'c

  illustrating the respective positions of the end rollers.

  Figure 3a illustrates the device in the inactive position of

  release as shown in Figure 1.

  Figure 3b illustrates the device between its inactive position

  release and its clamping position.

  Figure 3'b is an enlarged view of the roller and the means of

  inclined guidance when the device is in the position of Figure 3b.

  Figure 3c illustrates the locked device, the piston rod being

  in the locked position and the lever in the clamped position.

  Figure 3'c is an enlarged view of the roller and the means of

  inclined guide when the device is in the position of FIG. 3c.

  Figure 4 shows the body of the device in cross section

according to AA.

  FIG. 5 illustrates the body of the device in longitudinal section.

  Figure 6 is a view similar to Figure 4 showing the

  clamping device with its constituent elements.

  Figure 7 illustrates in perspective the arm protection member

  lever, the lever and the control and connecting means.

  FIG. 8 represents two curves illustrating the force for tightening the lever as a function of its position for the device according to the invention (line

  full) and for a conventional type device (dotted line).

  Figure 9 is an enlarged view of the roller, a portion of the connecting rod and inclined guide means when the device

  is between its inactive release position and its clamping position.

  The clamping device (1) according to the invention, of general median plane of symmetry (P), comprises a clamping lever bearing the general reference (2) mounted so as to pivot about a transverse axis of rotation (3) on a body of device (4), allowing said lever to be movable between two positions, a first position (A) illustrated in FIG. 1 and FIG. 3a, called the inactive position for releasing the part to be welded or machined, and a second position (B ) illustrated in FIG. 2, called the active clamping position. The clamping lever (2) is pivotally actuated about its axis (3) by the displacement of the piston rod (6) of a cylinder (7) of longitudinal axis (ZZ ') by means control and link (MC). Said means comprise at least one connecting rod (16) with longitudinal axis (RR ') pivotally mounted, on the one hand on the clamping lever (2) around a secondary pivot axis (23), and on the other hand around a main pivot axis (22) either on another member of said control and connection means (MC) or directly on the piston rod (6), and are thus intended to transmit

  to the clamping lever (2) the force supplied to the device (1) by the jack (7).

  According to the invention, the clamping device (1) comprises means for transmitting the force (MT) intended to allow obtaining a large and satisfactory clamping force (EF1), substantially constant during the pivoting of the lever. between a position close to a position called the attack position (C) and a position close to its position

active clamping (B).

  Clamping devices of the conventional type known in the prior art have a relatively low clamping force (EF) during the pivoting of the lever, from its inactive position (A) to a position (K) close to its active position of tightening (B), said force increasing suddenly between said position (K) and the tightening position (B), as shown in Figure 8 illustrating in dotted lines the force of force of the lever (EF) as a function of the position of the lever relative to its active clamping position, that is to say as a function of the parameter (k) illustrated in FIG. 3b. The device (1) according to the invention is intended to allow a satisfactory clamping force (EF) to be obtained (corresponding to a force (EF1) illustrated in FIG. 8) and constant for positions (K1, K2, K3) of the clamping lever remote from the clamping position (B) and from the position (K) as shown by the curve illustrated in solid lines in FIG. 8, this for an identical force supplied by the jack (7) to the clamping device (1 ) than

  in the case of conventional type devices.

  To do this, the clamping device (1) comprises guide means (MG) comprising inclined guide means (MI); said guide means (MG) being intended to guide the main pivot axis (22) of the connecting rod (16) in a trajectory at least partially inclined relative to the longitudinal axis (ZZ ') of the jack, they thus constitute the means for transmitting the force (MT) of the device. According to a preferred embodiment of the invention, the body (4) of the clamping device (1) consists of an upper part (9a) inside which pivots the clamping lever (2), and d 'a part

  lower (9b) in which slides the piston rod (6) of the cylinder (7).

  Note that the clamping device (1) comprises fixing means (MF) of said cylinder, so as to allow the adaptation to said device of several types of cylinder, as well as the easy replacement of a defective cylinder. According to the illustrated embodiment, said cylinder (7) is fixed to the lower part (9b) of the device (1) by means of four threaded rods (43) arranged longitudinally parallel to the axis (ZZ ') to the four corners of its cross section and which thus constitute said fixing means (MF). According to this preferred embodiment, the piston rod (6) movable in translation is of cylindrical shape; in addition, the seal between the cylinder (7) and the piston rod (6) can advantageously be obtained using lip seals so as to

  allow the inclination of said rod while minimizing wear on the seals.

  According to the preferred embodiment of the invention illustrated in FIGS. 3a, 3b, 3c, 4, 5, 6 and 7, the upper part (9a) of the body (4) of the clamping device has the general shape of a yoke ( 100) which is formed by two parallel side walls (O10a, 10b) creating between them a slot (11) of width L1 intended for the passage of the lever (2), said parallel side walls (10a, 10b) are, moreover, drilled a transverse hole (12) of axis (XX ') in which is engaged the transverse axis of rotation (3) of

  lever (2) as illustrated in Figure 2a, 4 and 5.

  Said lever (2) comprises a lever arm (14) extending an embedding part (13) which constitutes its actuation and pivoting part on which is pivotally mounted the connecting rod (16) of the control and connection (MC) as illustrated in FIGS. 3a, 3b, 3c and 7. In addition, the lever (2) advantageously comprises a protective member (15), as shown in FIGS. 2a, 2b and 7 secured in rotation to the arm lever (14), said member being intended to cover the parts of the lever (2) which, when it is pivoted from its clamping position (B) to its inactive position (A), move from the outside (EX) of the yoke (100) inside (IN) thereof. Said member comprises, on the one hand, an upper wall (15a) of width L2 adjusted to the width L1 of the slot and whose external shape is circular with radius Ri, centered on the axis (XX ') and, d' on the other hand, two lateral protective cheeks (40a, 40b) extending said upper wall (S15a) and whose external faces are thus distant from the width L2. Said cheeks (40a, 40b) have the shape of a sector of a circle centered on the axis (XX ') of radius Ri. The protective member is advantageously made according to the use made of the device (1) in a material intended to allow projections and other dirt not to adhere to it, such as, for example, aluminum alloy when uses the device (1) to perform welding on steel parts. Note, moreover, that it is hollowed out in its rear part so as not to interfere with the internal mechanism of the device when the lever is pivoted from its active clamping position (B) to its release position (A). According to the preferred embodiment, the lower part (9a) of the body (4) forms a closed chamber (17), inside which is arranged the actual mechanism of the clamping device (1). It consists of two side walls (18a, 18b) respectively extending the two parallel side walls (O10a, 10b) of the yoke (100) as well as a rear wall (19) and a front wall (20), the wall rear extending

  advantageously up to the slot (11) of the yoke (100).

  According to the preferred embodiment, the lower part (9a) of the clamping device (1) is mounted directly on a pneumatic or hydraulic cylinder (7) with a longitudinal axis (ZZ '), the end (8) of the rod piston (6) is intended to move substantially vertically between an expansion position (A1), illustrated in Figure 3a, corresponding to the inactive position (A) of the lever (2) and a so-called locking position (B1), illustrated in Figure 3c o the lever is in its active clamping position (B). Note that as in all clamping devices using the toggle principle, between the two positions (A1, B1) of the piston rod, the latter passes through an intermediate clamping position (Dl) not shown, during which the lever arm (14) has just pivoted to be in its active clamping position (B), said lever remaining in its active position (B) while the piston rod passes from said intermediate clamping position ( Dl) to its locking position (B1) and vice versa. Note that the positions (A1, B1 and Dl) of the end of the piston rod correspond to the positions (A'1, B'1 and D'1) of the end roller on the

  inclined guide rails described later.

  According to a preferred embodiment, the control and connection means (MC) are constituted by an intermediate piece movable in translation (21) carried by the piston rod (6) of the jack (7) and integral in displacement with the end (8) of said rod and by the connecting rod (16) pivotally mounted at one of its ends on said intermediate piece around the main pivot axis (22) and mounted at the other of its ends on the arm lever (14) or the mounting part (13) of the clamping lever. (2) around a secondary pivot axis (23), as shown in Figures 3a, 3b and 3c. Note that the length of the link (L5), that is to say the distance between the main and secondary pivot axes (22, 23) is less than the orthogonal distance (L6) between the pivot axis (XX ', 3) of the lever (2) and the longitudinal axis (ZZ') of the piston rod (6). Said intermediate part has the general shape of a U consisting of an end wall (21c) and two vertical side walls (21a, 21b) distant by a distance L3, as shown in FIGS. 6 and 7. Said vertical side walls carry transversely at their upper ends (25a, 25b) the main pivot axis (22) on which is mounted the connecting rod (16). Said axis (22) is provided at each of its ends with a roller or end bearing (24a, 24b) intended to be guided in its movement

  substantially vertical by the guide means (MG).

  Note that the connecting rod (16) is mounted at one of its ends between the vertical side walls (21a, 21b) of the intermediate piece (21) and at the other of its ends in a slot (26) located in the mounting part (13) of the lever (2). It goes without saying that the device could for example comprise two parallel connecting rods arranged on either side of the sliding part and of the embedding part of the lever without however departing from the protective field of the invention. Similarly, said link (16) and its axis (22) could be mounted directly on the end of the piston rod,

for example.

  According to this preferred embodiment of the invention, the guide means (MG) intended to guide the main pivot axis (22) consist of two blind guide slots (30a, 30b) located on the internal faces (28a , 28b) of the side walls (10a, 10b, 18a, 18b) of the body (4) of the device (1), as shown in Figures 4, 5 and 6. Said blind lights (30a, 30b) each have a ramp of vertical rectilinear guide (50a, 50b) extended by an inclined guide ramp (27a, 27b), said inclined ramps constituting the means for

  inclined guide (MI) of the guide means (MG).

  Thus, the main pivot axis (22) and therefore the intermediate part (21) and the end (8) of the piston rod (6) which are integral with it are driven in a rectilinear and vertical axis trajectory ( ZZ '), on the one hand, then successively in an inclined path relative to said axis (ZZ'), on the other hand, when the end rollers (24a, 24b) of said main axis are guided in the slots (30a , 30b) successively along the vertical rectilinear ramps (50a, 50b) then inclined ramps (27a, 27b) thus allowing the piston rod (6) to move between its expansion positions (A1) and its locking position (B1) illustrated respectively in Figures 3a and 3c. Note therefore that said positions (A1, B1) of the end of the piston rod (8) correspond respectively to the position (A'1) of the rollers (24a, 24b) on the straight guide rails (50a, 50b) and at the position (B'1) of said

  rollers on the inclined ramps (27a, 27b) illustrated in Figure 3'b and 3'c.

  According to the preferred embodiment of the invention, said ramps (27a, 27b) are constituted by independent parts intended to be positioned and fixed in ramp housings located in the internal faces (28a, 28b) of the side walls (10a , 10b, 18a, 18b) of the body (4). Said ramps are positioned so that they are traversed by the end rollers (24a, 24b) of the main pivot axis (22) between a first position of the rollers called the attack position (C'I) , illustrated in Figure 3'b and a second position of the rollers known as the locking position (B'I) illustrated in Figure 3'c. On the one hand, note that the position (C'1) of the rollers corresponds to a position (Cl) of the end of the piston rod (8) located between its expansion position (A1) and its intermediate clamping position ( Dl) as well as at an intermediate position (C) of the lever as illustrated in FIG. 3b, and on the other hand that the position (B'1) of the rollers corresponds to the locking position of the rod (B1) illustrated in FIG. 3c. In addition, according to the preferred embodiment, said ramps are positioned in the space located above the plane

  horizontal (Hi) containing the axis of rotation (3) of the lever (2).

  Note, moreover, that the ramps (27a, 27b) are advantageously inclined in the median plane (P) so as to extend upward (HA) in the direction of the clamping lever (2). They are advantageously curved either over their entire length as shown in Figures 3'b and 3'c or only on the portion where the rollers pass from their attack position (C'I) to their intermediate position. clamping (D'i) corresponding to the intermediate position (Dl) of the rod, then can be straight between the positions

  clamping (D'I) and locking (B'I) intermediate rollers.

  During the course of the inclined ramps (27a, 27b) by the rollers (24a, 24b) of the pivot axis (22) carrying the connecting rod (16), the longitudinal axis (RR ') of said rod forms a angle c (with the line (Q), said line (Q) being the line perpendicular to the tangent (T) to the inclined ramp at point M traversed by the roller as shown in Figure 9. Note that the inclined ramps (27a , 27b) are curved so that the angle a is substantially constant during said travel of the rollers between their attack position (C'1) and a position close to

  their intermediate clamping position (D'I).

  Thus, as shown in FIGS. 3'b and 3'c, the end rollers (24a, 24b) are guided in the slots (30a, 30b) along the longitudinal axis (ZZ ') between the relaxation positions (A 'I) and attack (C'1) then along an inclined trajectory with respect to the axis (ZZ') between the position of attack (C'1) and locking (B'1) passing through the intermediate clamping position (D'1). Therefore, when the rollers pass from their positions (C'1) to their position (B'1) by traversing the inclined ramps (27a, 27b) the orthogonal distance (d) between the main pivot axis (22) which carries them and the longitudinal axis (ZZ ') increases as shown in Figure 3'c, therefore the distance between the axis (ZZ') and the end of the piston rod (8) which passes from position (C1) at

  the position (B1) also increases.

  It goes without saying that said ramps could be machined directly inside the blind lights; however, the curvature of the ramps must be machined with precision in order to obtain the expected effect of increasing the transmitted force, it therefore seems preferable to make them separately before positioning and fixing them in housings located in the extension of the vertical straight ramps of the blind lights. Note that the parts comprising said ramps

  can be advantageously made of steel.

  Note, moreover, that the vertical side walls (21a, 21b) of the intermediate piece (21) are distant by a distance L3 greater than the width L2 of the upper wall (15a) of the protective member (15) , so that the latter can, when it is pivoted towards the inactive position (A) of the lever, become housed in the space (29) located between said vertical walls. In addition, the member (15) of circular external shape is hollowed out in its rear portion so as not to interfere with the main pivot axis (22) in the inactive release position.

(A) of the clamping lever (2).

  According to the preferred embodiment, the clamping device (1) comprises a detection system (SD) which can advantageously be of the electromagnetic type comprising at least two sensors (41a, 41b) arranged inside the chamber (17) of the body (4) intended to detect the position in which the clamping device is located, i.e. the lever arm (14) or the piston rod (6), by sending a signal to a control unit when the clamping device is in their detection position. Said sensors (41a, 41b), as shown in FIGS. 3a, 3b, 3c and 6, can be arranged along the front wall (20) and against a side wall (18b) of the body (4) in order to be able to detect the position

  a detection finger (42) integral with the intermediate piece (21).

  It goes without saying that one can limit the amplitude of the pivoting of the lever arm by adding a stop ring of the device around the

  piston rod in order to modify the length of the stroke of said rod.

  Similarly, a variant consists in modifying the shape of the lever arm to give it a suitable shape so that the clamping device can effect the clamping of a piece to be welded

  against a vertical plane or an inclined plane, for example.

  Of course, the invention is not limited to the embodiments described and shown by way of examples, but it includes

  also all technical equivalents and their combinations.

Claims (12)

  1. Clamping device (1) intended to retain a construction part to be machined or welded, of the type comprising a lever (2) mounted to pivot about an axis of rotation (XX ', 3) relative to a body of device (4) for being pivotally actuated by the displacement of the piston of a cylinder (7) with a longitudinal axis (ZZ ') between a first position (A) called the inactive release position, and a second position (B) called active clamping position, said lever (2) being connected to the end (8) of the piston rod (6) by means of control and connection means (MC) characterized in that it comprises means of force transmission (MT) intended to allow a substantially constant tightening force of the lever (2) (EF1) to be obtained while said lever pivots between an attack position (C) distant from the position clamp (B) and a   position close to the lever clamping position (B).   2. Clamping device (1) according to claim 1 characterized in that the control and connection means (MC) comprise at least one connecting rod (16) of longitudinal axis (RR ') pivotally mounted, of a part on the clamping lever (2) around a secondary pivot axis (23), and secondly either on a member of said control and connection means (MC) or directly on the piston rod (6) around a main pivot axis (22) and in that the force transmission means (MT) consist of guide means (MG) intended to guide the main pivot axis (22) in a trajectory at least partly inclined with respect to the axis longitudinal (ZZ ').   3. Clamping device (1) according to claim 2, characterized in that the connecting rod (16) is pivotally mounted at one of its ends around a main pivot axis (22) on an intermediate piece movable in translation (21) control and connection means (MC), said part being carried by the end (8) of the piston rod (6) and at the other of its ends around a secondary pivot axis ( 23) on the mounting part (13) or the arm (14) of the lever clamping (2).   4. Clamping device (1) according to any one of   Claims 2 and 3 characterized in that the guide means (MG)   include inclined guide means (MI) constituted by inclined ramps (27a, 27b) intended to guide end rollers (24a, 24b) arranged on the main pivot axis (22) along a trajectory   at least partly inclined with respect to the longitudinal axis (ZZ ').   5. Clamping device (1) according to claim 4, characterized in that the guide means (MG) consist of blind guide lights (30a, 30b) located on the internal faces (28a, 28b) of the side walls (18a, 18b) of the body of the device (4), said lights comprising vertical rectilinear ramps (50a, 50b) extended by the inclined ramps (27a, 27b).   6. Clamping device (1) according to claim 5, characterized in that the inclined ramps (27a, 27b) are located above the plane   horizontal (Hi) which contains the axis of rotation (3) of the lever (2).   7. Clamping device (1) according to any one of   Claims 2 to 6, characterized in that the guide means (MG)   comprise inclined guide means (MI) constituted by   inclined ramps (27a, 27b) at least partially curved.   8. Clamping device (1) according to one of claims 4 to 7   characterized in that the inclined ramps (27a, 27b) are inclined upwards (HA) and towards the lever (2) relative to the longitudinal axis (ZZ ')   in a median plane (P) of general symmetry of the clamping device (1).   9. Clamping device (1) according to any one of   claims 2 to 8 characterized in that the distance (L5) between the axis of   main pivot (22) and the secondary pivot axis (23) carried by the connecting rod (16) is less than the orthogonal distance (L6) between the longitudinal axis of the jack (ZZ ') and the axis of rotation (XX ', 3) of the clamping lever (2) 10. Clamping device according to claim 4 and one   any one of claims 2 to 9 characterized in that the ramps   inclined (27a, 27b) are curved so that the angle C formed at a point M of the inclined ramps between the longitudinal axis (RR ') of the connecting rod (16) and the line (Q) perpendicular to the tangent (T) to the inclined ramp at point M o is the roller (24a, 24b) is substantially constant when the end rollers (24a, 24b) travel through said ramps between an attack position (C'1) and an   position close to an intermediate clamping position (D'1).   11. Clamping device (1) according to any one of   previous claims characterized in that it comprises a member   protection (15) integral in rotation with the lever (2) which comprises an upper wall (15a) of circular shape and two lateral cheeks (40a, b). 12. Clamping device (1) according to any one of   previous claims characterized in that it comprises a system detection (SD).