FR3122843A1 - clamping device - Google Patents

Abstract

Clamping device. The invention relates to a device D for clamping a part on a tool, comprising a cylinder 1 and a clamp 2, the clamp 2 being articulated around a pivot axis X and moving over a determined stroke between a position of tightening and a release position, this device D also comprising fixed and mobile guide members 3 cooperating to drive the flange 2 following a rotational movement around the pivot axis X at least at the end of its travel towards its position release and following a translation movement at least at the end of its travel towards its tightening position, this device D further comprising fixed and mobile support elements 4 cooperating selectively, at least at the end of the travel of the flange 2 towards its clamping position, to mutually offer, at a distance from the guide members 3, a sliding contact parallel to the translational movement of the flange and allowing an arching of the flange 2 on the part to be clamped, this device if clamping D further comprising at least one cover cap 5, 5a, 5b comprising a first end 50 cooperating with the flange 2 by a pivoting connection and a second end 51 cooperating with the body 10 by a connection in translation. Figure for abstract: Fig.13

Description

clamping device

The invention relates to a clamping device having a small footprint. More specifically, the invention relates to a device configured to clamp a part to a tool during a machining operation, for example.

In fact, the invention is a device of the type comprising a cylinder and a clamp actuated by the cylinder, said clamp being able to pass from a clamping position of a part to be clamped to a release position for which the clamp is in the position of withdrawal. This release position makes it easier to fit or remove the part to be tightened on said device.

Such an example of a flange is presented in the document EP1697088B1. There is described a device for clamping a part on a tool, comprising a cylinder and a clamp, the cylinder being selectively actuated by a pressurized fluid and itself comprising a body fixed in operation to the tool and a rod movable relative to the body, and the flange being articulated around a pivot axis on the rod and selectively driven by the rod, this flange struggling over a determined stroke between a tightening position and a release position, and undergoing rotation over at least part of its travel.

In fact, document EP1697088B1 presents a device for clamping a part on a tool, comprising a cylinder and a clamp, the cylinder being selectively actuated by a pressurized fluid and itself comprising a body fixed in operation to the tool. and a movable rod relative to the body, and the flange being articulated around a pivot axis on the rod and selectively driven by the rod, this flange struggling over a determined stroke between a tightening position and a release position, and undergoing rotation over at least part of its travel. This device further comprises guide members and support elements, these guide members comprising a guide member fixed relative to the body and a movable guide member linked to the flange, these fixed and movable guide members cooperating to drive the flange in a rotational movement around the pivot axis at least at the end of its travel towards its release position and in a translational movement at least at the end of its travel towards its tightening position. In addition, these support elements comprise a support element fixed relative to the body and a mobile support element linked to the flange, these fixed and mobile support elements cooperating selectively, at least at the end of the stroke of the flange towards its clamping position, to offer each other, at a distance from the guide members, a sliding contact parallel to the translational movement of the flange and allowing an arching of the flange on the part to be clamped.

The device thus described therefore comprises a flange passing from a clamping position to a release position and vice versa by successive and combined translation and rotation movements.

This clamping device has the advantages of being compact, fast, retractable, powerful, and moreover with a clamp that is not very subject to buckling.

However, despite all these advantages compared to other existing clamps, such a device still has drawbacks.

A first drawback lies in the fact that such a device has openings through which the mechanisms of the device are visible and accessible through which machining chips, dust, fluids of all kinds can enter.

This can cause seizures during the operation of the clamping device.

It may be envisaged to protect the device with a silicone bellows covering the housings, openings and crevices, but this is detrimental to the compactness of the clamping device. In addition, the complex movement of the flange does not ensure a good rollover with this type of protection. Finally, this type of elastomer bellows-type protection can quickly degrade under the action of chemical attacks from the fluids in contact as well as the contact of hot shavings.

A second drawback lies in the fact that the flange of the device must pass from a release position to a clamping position quickly under the action of a pressurized fluid actuating the cylinder, therefore with a rapid fluid flow. But it is also necessary for the clamp to come into the clamping position on a part to be clamped with a sufficient clamping force, but below a determined maximum threshold, for example to prevent the clamping force from damaging the part. to be machined, which requires a very fine adjustment of the pressure of the pressurized fluid actuating the jack, with a slower fluid flow.

To meet these two requirements, it is necessary for the device to be able to switch from a fast flow of fluid under pressure to a slower flow and vice versa at a determined moment which can vary according to the flange and the cylinder stroke. . To determine this moment, it is possible to seek to precisely detect the position of the flange of the device in its travel causing it to pass from the release position to the clamping position of the part to be clamped. To do this, the device can be fitted with a flange displacement detector, but this constitutes costly additional equipment which must be electrically powered. This is detrimental to obtaining a device that is simple to produce.

A third drawback lies in the fact that the flange of the device has a beak, the flat end of which is configured to bear against a surface of the part to be clamped. Sometimes the surface is not parallel to the flat end of the spout. In this case, the support of the nose on the part is punctual, and the part can slip or the surface can be marked by the nose.

In this context, the object of the invention is to propose an improved clamping device having, as a preamble, the characteristics of the clamping device described above but free from all or part of the defects mentioned above.

To this end, the invention relates to a device for clamping a workpiece on a tool, comprising a cylinder and a clamp, the cylinder being selectively actuated by a pressurized fluid and itself comprising a body fixed in operation to the tooling and a rod movable relative to the body, and the flange being articulated around a pivot axis on the rod and selectively driven by the rod, this flange struggling over a determined stroke between a tightening position and a release position , and undergoing rotation over at least part of its travel, this device further comprising guide members and support elements, these guide members comprising a guide member fixed relative to the body and a movable guide member linked to the flange, these fixed and mobile guide members cooperating to drive the flange following a rotational movement around the pivot axis at least at the end of its travel towards its release position and following vant a translational movement at least at the end of its travel towards its clamping position, and these support elements comprising a support element fixed relative to the body and a movable support element connected to the flange, these elements fixed and mobile support cooperating selectively, at least at the end of the stroke of the flange towards its clamping position, to offer each other, at a distance from the guide members, a sliding contact parallel to the translational movement of the flange and allowing an arching of the flange on the part to be tightened.

Advantageously, this clamping device comprises at least one cover cap comprising two ends, a first end cooperating with the flange by a pivoting connection, a second end cooperating with the body by a translational connection.

This makes it possible to propose a clamping device which remains compact while providing simple and economical protection against seizing elements, this protection being able to follow the complex movements of the clamp.

According to a particular feature of the invention, the first end of the covering cowl(s) comprises two shafts coming from the cowl and extending laterally in opposite directions, cooperating by interlocking in reciprocal bearings of the flange to form connecting means pivoting.

According to another feature of the invention, the second end of the cover or covers have side edges configured to slide in slideways facing each other of the body to form connection means in translation.

This envisaged protection is simple to mount on the clamping device.

According to another feature of the invention, the at least one cover cap comprises an elastically deformable part.

This makes it possible to follow the movements of the bridle even more precisely.

According to another feature of the invention, this clamping device comprises a cover cap whose elastically deformable part has a configuration without deformation when the clamp is in the clamping position, and which has a deformed configuration when the clamp is in the clamping position. relaxation.

According to another feature of the invention, this clamping device comprises a cover cap, the elastically deformable part of which has a configuration without deformation when the clamp is in the release position, and which has a deformed configuration when the clamp is in the released position. Tightening.

According to yet another feature of the invention, the clamping device comprises detection means configured to detect when the clamp is in translation only during the movement of the clamp from the release position to the tightening position, these detection means comprising an orifice in the body configured to be closed off by the flange during its sliding contact parallel to the translational movement against said body of the device, said orifice being continued by an air supply channel.

The detection means make it possible to know the position of the flange by plugging the orifice, which varies the pressure in the air supply channel. A pressure sensor at the supply means of this channel thus makes it possible to detect a blockage of the orifice when the flange passes from the release position to the tightening position, and that the flange is in a translational movement alone . It is then possible to control the flow rate and the pressure of the fluid of the cylinder of the device in order to reduce it and carry out a fine adjustment of the tightening. Adjusting the position of the orifice along the body of the device defines when the fluid flow is reduced.

According to yet another feature of the invention, the clamping device comprises two flanges parallel to each other longitudinally and two respective cylinders.

This makes it possible to provide clamping on two close areas, and increase the clamping surface of the ends of the clamps on a surface of a part to be clamped. This is especially true if this surface is not parallel to the ends of the flanges.

According to an alternative or complementary embodiment of the invention, each flange of the clamping device comprises a spout having at its end a flat zone pivotally mounted on a ball joint.

This allows the contact of the nose of the flange or flanges on the surface of the part to be made on a surface and not on a line or a point.

Other aims and advantages of the present invention will appear during the description which will follow, referring to the attached drawings illustrating an example embodiment and in which:

is a front perspective view of a clamping device having characteristics of a clamp and of a jack known from the state of the art;

is a rear perspective view of a clamping device of the ;

is a partial sectional view of the device illustrated in Figures 1 and 2 but whose flange is in the release position, the section being made along a plane parallel to the median plane of this device;

is a sectional view of the device illustrated in FIGS. 1 and 2, taken along the median plane of this device;

is a front perspective view of a device for clamping in the maximum tightening position according to the invention, said device comprising in particular the characteristics of the clamp and of the cylinder of the device of the ;

is a rear perspective view of the clamping device of the ;

is a sectional view of the device illustrated in FIGS. 5 and 6, taken along the median plane of this device;

is a front perspective view of the clamping device of the when the clamp is in the intermediate position between the release position and the tightening position, in the translation position only;

is a rear perspective view of the clamping device of the ;

is a sectional view of the device illustrated in FIGS. 8 and 9, taken along the median plane of this device;

is a front perspective view of the clamping device of the when the strap is in the maximum release position;

is a rear perspective view of the clamping device of the ;

is a sectional view of the device illustrated in FIGS. 11 and 12, taken along the median plane of this device;

As shown in Figures 5 and following, the present invention relates to a clamping device D for clamping a workpiece. This clamping device D comprises a cylinder 1 and a clamp 2. The clamp comprises a nose 20 oriented towards a so-called forward direction when the clamping device D is in the clamping position as illustrated in the . The clamping device has in fact a front and a rear defined by the beak 20. The left side of Figures 4, 7, 10 and 13 is considered to be facing forward, and the right side is considered to be facing towards back.

The operation of the clamping device D with regard to the movement of the clamp 2 under the action of the jack 1 incorporates the characteristics described in the document EP1697088B1 and reproduced below. Figures 1 to 4 correspond respectively to Figures 1, 2, 4 and 5 of said document EP1697088B1 and show a clamping device according to the prior art.

Thus, the cylinder 1 is a double-acting hydraulic cylinder and comprises a body 10 fixed in operation to the tool itself arranged for example in a machining center, and a rod 11 movable relative to the body 10 of this cylinder .

The body 10 of the cylinder has a bore inside which a piston 12, integral with the rod 11, delimits a first chamber 101 and a second chamber 102 of variable and complementary volumes, each of which can be connected to a hydraulic source of high pressure while the other is connected to a low pressure tank.

The flange 2, which is articulated on the rod 11 around a pivot axis X, is driven at will by the rod 11, itself driven by the piston 12.

The flange 2 thus struggles, over a determined stroke, between a clamping position illustrated in particular in Figures 1, 2, 4, and in Figures 5 to 7, and a release position, illustrated in Figures 3 and 11 to 13.

Under these conditions, the flange 2 is driven from its release position to its clamping position by admission of pressurized fluid into the first chamber 101 of the cylinder 1, and is driven from its clamping position to its release position by admission of fluid under pressure in the second chamber 102 of this cylinder 1.

The device D comprises guide members 3 and support elements 4, the guide members 3 themselves comprising a guide member 31 fixed relative to the body 10 and a movable guide member 32 connected to the flange 2, and the support elements 4 comprising, in the same way, a support element 41 fixed relative to the body 10 and a movable support element 42 linked to the flange 2.

The fixed and mobile guide members, 31 and 32, cooperate to drive the flange 2 following a rotational movement around the pivot axis X at least at the end of the travel of this flange towards its release position, and to drive the flange 2 following a translational movement at least at the end of the race of this flange towards its clamping position.

For their part, the fixed and mobile support elements, 41 and 42, cooperate, at least at the end of the race of the flange 2 towards its clamping position, to offer each other, at a distance from the guide members 3 , a sliding contact parallel to the translational movement of the flange 2 and allowing an arching of the flange 2 on the part to be clamped.

Advantageously, the rod 11 preferably extends along a translation axis Z which passes between the guide members 3 and the support elements 4.

Here, the movable guide member 32 comprises a cam formed by two grooves, symmetrically cut into the flange 2 on either side of a median plane M of the device, this median plane M being transverse to the pivot axis X and constituting a plane of symmetry for the flange 2 and for the rod 11. Each of the grooves has a path which continuously approaches the pivot axis X from the first end 321 of this path towards its second end 322. This path comprises a rectilinear path portion 320r which terminates at the first end 321 and a curved path portion 320c, adjacent to the rectilinear path portion 320r and terminating at the second end 322.

The has only one cam, the other cam being deduced by symmetry with respect to the plane M.

The fixed guide member 31 is itself constituted by a pair of studs or rollers, fixed to the body 10 of the cylinder 1 and respectively engaged in the grooves forming the cam. The body 10 comprises two studs or rollers 31, one visible on the , the other being deduced by symmetry with respect to the plane M.

As shown in , each stud or roller 31 is located above a plane T which is transverse to the rod 11 and which contains the pivot axis X, when following a direction which corresponds to the movement carried out by the rod 11 for drag strap 2 to its release position.

The movable support element 42 consists of a support heel which is carried by the flange 2 and which extends symmetrically on either side of the median plane M of the device.

The fixed support element 41 is itself constituted by an external support surface of the body 10 of the cylinder 1, on which the support heel 42 is supported symmetrically with respect to this same median plane M.

In the embodiment of the invention illustrated here in the figures, the rod 11 comes out of the cylinder 1 on the side of its first chamber 101.

In this case, the fixed guide member 31 and the fixed support element 41 are advantageously carried by a part 100 of the body 10 of the jack which is shaped as a yoke, and the flange 2 is then guided in its median plane M between two parallel faces facing each other, 100a and 100b, belonging to this part 100 forming a yoke. This embodiment allows significant rotation of the flange 2 between its tightening position and its release position, typically a rotation of amplitude equal to or greater than 90 degrees.

In addition to these elements described above, the clamping device D comprises at least one cover cap 5, for example in the form of a plate having two ends 50, 51 and two side edges 52. The at least one cover cap 5 is placed between the two parallel faces 100a and 100b, belonging to the part 100 forming the yoke, and perpendicular to these faces.

The at least one cover 5 comprises a first end 50 in the direction of the flange 2. This first end 50 cooperates with this flange by a pivot connection called pivot connection. To do this, the at least one cover cover 5 comprises two shafts carried by the same virtual axis of rotation parallel to the pivot axis X. These two shafts come from the first end 50 of the cover 5 and extend in opposite directions. These shafts cooperate by interlocking in reciprocal bearings hollowed out in the flange 2. The bearings and the shafts form pivoting connection means between the at least one cover 5 and the flange 2.

Of course, other embodiments of a pivot connection can be envisaged in the spirit of the invention.

The at least one cover 5 comprises a second end 51 opposite the first end 50. This second end 51 cooperates with the body 10 of the clamping device D by a sliding connection called a translational connection. In fact, the two parallel faces 100a and 100b, belonging to the part 100 comprise grooves forming slides in which the side edges 52 slide or slide. The slides and the edges form sliding connection means.

Of course, here also other embodiments of a pivot connection can be envisaged in the spirit of the invention.

The at least one cover 5 may also comprise an elastically deformable zone 53, in particular under the action of a force whose vector is parallel to the median plane M.

According to an embodiment of the invention illustrated in Figures 5 to 13, the clamping device D comprises a front cover 5a on the front of the clamping device D as particularly illustrated in Figures 5, 8 and 11, and it comprises a rear covering cap 5b on the rear of the clamping device D as particularly illustrated in FIGS. 6, 9 and 12. The cross-sectional views of FIGS. same figures the front 5a and rear 5b cover covers. These sectional views also make it possible to clearly distinguish the deformation zones 53 of the cover caps 5a, 5b. As can then be seen in these figures, the elastically deformable part 53 of the front cover 5a is not deformed when the flange 2 is in the tightening position, and it is deformed when the flange 2 is in the release position. Conversely, the elastically deformable part 53 of the rear cover 5b is not deformed when the flange 2 is in the release position, and it is deformed when the flange 2 is in the tightening position. Thus the covers follow the complex movement of the flange 2 to protect in a simple and compact way the mechanisms of this clamping device D.

Each cover cap 5a, 5b is preferably but optionally made of metallic material, in particular steel.

According to a particular embodiment of the invention, the fixed support element 41 of the clamping device D comprises on its surface against which the movable support element 42 of the clamp 2 slides an orifice 6. This orifice 6 is continued by an air supply channel. Air is blown through this channel and this orifice 6.

When the movable support element 42 closes the hole 6 by sliding against the fixed element 41 by translation, an increase in the pressure of the air blown into the orifice 6 then blocked can be detected. We then know that the clamp 2 has finished its pivoting and that it is entering its translation phase to come into contact with the part to be clamped and then come to butt against it. It is then possible to lower the flow rate of the fluid supplying the cylinder 1 of the clamping device D to finely adjust the descent of the clamp 2 and the clamping force.

Thus, inexpensively and simply, detection means are obtained for detecting when the flange is in translation only during the movement of the flange from the release position to the tightening position. These detection means include, among other things, the orifice 6.

A second orifice in the upper part of the body also connected to the channel advantageously makes it possible not to completely block the air supply channel.

According to yet another particular embodiment of the invention not illustrated here, the clamping device comprises two flanges parallel to each other longitudinally in a front/rear direction. Each flange is controlled by a corresponding cylinder. Each flange may have a single roller or stud moving in a cam. The device may also comprise a central plate carried by the median plane M in which two cams are placed and in which rollers or studs act independently attached to only one of the flanges 2.

According to another particular embodiment of the invention not illustrated here, the spout 20 of the clamp 2 comprises a movable element in ball joint connection at its end configured to be inserted between the spout 20 and a part to be clamped. This mobile element comprises on the one hand a ball joint which is embedded in a housing corresponding to the end of the spout 20, and on the other hand a flat zone configured to come opposite and in contact with a part to be clamped. Of course, this embodiment can be applied to the two flanges 2 of the embodiment of the device described in the previous paragraph.

A clamping device D is thus obtained that is compact, robust, and more resistant to attack from its environment. Its lifespan is improved and its maintenance reduced.

The adjustment of the descent of the flange 2 towards its clamping position can be done at appropriate speeds and this at little cost and by means that do not require significant maintenance.

In addition, this clamping device also provides better support for the parts to be clamped and limits the creation of clamping marks on the part to be clamped.

Claims (9)

Clamping device (D) of a part on a tool, comprising a jack (1) and a flange (2), the jack (2) being selectively actuated by a pressurized fluid and itself comprising a body (10) fixed in operation to the tool and a rod (11) movable relative to the body (11), and the flange (2) being articulated around a pivot axis (X) on the rod (11) and selectively driven by the rod (11), this clamp (2) struggling over a determined stroke between a tightening position and a release position, and undergoing a rotation over at least part of its stroke, this clamping device (D) comprising in addition to guide members (3) and support elements (4), these guide members (3) comprising a fixed guide member (31) relative to the body (10) and a movable guide member (32) linked to the flange (2), these fixed and mobile guide members cooperating to drive the flange (2) in a rotational movement around the pivot axis (X) at least at the end of its travel towards its release position and following a translation movement at least at the end of its travel towards its tightening position, and these support elements (4) comprising a fixed support (41) with respect to the body (10) and a mobile support element (42) connected to the flange (2), these fixed and mobile support elements cooperating selectively, at least at the end of the the flange (2) towards its clamping position, to provide each other, at a distance from the guide members (3), with a sliding contact parallel to the translational movement of the flange (2) and allowing an arching of the flange (2) on the part to be clamped, this clamping device (D) comprising at least one cover cap (5,5a,5b) comprising two ends, a first end (50) cooperating with the clamp (2) by a connection in pivoting, a second end (51) cooperating with the body (10) by a connection in translation. Clamping device (D) according to claim 1, characterized in that the first end (50) of the covering cover(s) (5,5a,5b) comprises two shafts coming from the cover (5,5a,5b) and s 'extending laterally in opposite directions, these shafts cooperating by interlocking in reciprocal bearings of the flange (2) to form pivoting connection means. Clamping device (D) according to one of the preceding claims, characterized in that the covering cap(s) (5, 5a, 5b) have lateral edges (52) configured to slide in slideways facing one on the other of the body (10) to form means of connection in translation. Clamping device (D) according to one of the preceding claims, characterized in that the at least one cover cap (5,5a,5b) comprises an elastically deformable part (53). Clamping device (D) according to claim 4, characterized in that it comprises a cover cap (5a) whose elastically deformable part (53) has a configuration without deformation when the clamp (2) is in the clamping position , and which has a deformed configuration when the clamp (2) is in the released position. Clamping device (D) according to Claim 4 or Claim 5, characterized in that it comprises a cover cap (5b) whose elastically deformable part (53) has a configuration without deformation when the clamp (2) is in the tightening position, and which has a deformed configuration when the flange (2) is in the release position. Clamping device (D) according to one of the preceding claims, characterized in that it comprises detection means configured to detect when the clamp (2) is in translation only during the movement of the clamp (2) of the release position towards the tightening position, these detection means comprising an orifice (6) in the body (10) configured to be closed by the flange (2) during its sliding contact parallel to the translational movement against the said body (2 ) of the clamping device (D), said orifice (6) being continued by an air supply channel. Clamping device (D) according to one of the preceding claims, characterized in that it comprises two flanges (2) parallel to each other longitudinally and two respective cylinders (1). Clamping device (D) according to one of Claims 1 to 7, characterized in that the flange (2) of the clamping device (D) comprises a nose (20) having at its end a flat zone mounted pivoting on a ball joint.