Clamping device

Abstract

The invention relates to a device D for clamping a part on a tooling, comprising an actuator 1 and a clamp 2, the clamp 2 being articulated about a pivot axis X and moving over a defined path between a clamping position and a release position, this device D also comprising fixed and movable guide members 3 which cooperate to drive the clamp 2 with a rotational movement about the pivot axis X at least at the end of its path towards its release position and with a translational movement at least at the end of its path towards its clamping position, this device D further comprising fixed and movable bearing elements 4 which cooperate selectively, at least at the end of the path of the clamp 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 clamp and allowing the clamp 2 to be braced on the part to be clamped, this clamping device D further comprising a covering hood 5, 5a, 5b comprising a first end 50 cooperating with the clamp 2 by a pivot connection and a second end 51 cooperating with the body 10 by a translational connection.

Description

Description Title of the invention: clamping device

[0001] The invention relates to a compact clamping device. More specifically, the invention relates to a device configured to clamp a workpiece onto a tool during a machining operation, for example.

[0002] In fact, the invention is a device of the type comprising a cylinder and a flange actuated by the cylinder, said flange being able to move from a clamping position for a workpiece to a release position in which the flange is retracted. This release position facilitates the placement or removal of the workpiece on said device.

[0003] Such an example of a flange is presented in document EP1697088B1. It describes a device for clamping a part onto a tool, comprising a cylinder and a flange, 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 about a pivot axis on the rod and selectively driven by the rod, this flange moving over a determined stroke between a clamping position and a release position, and undergoing rotation over at least part of its stroke.

[0004] In fact, document EP1697088B1 presents a device for clamping a workpiece onto a tool, comprising a cylinder and a clamp. The cylinder is selectively actuated by a pressurized fluid and comprises a body fixed to the tool during operation and a rod movable relative to the body. The clamp is articulated about a pivot axis on the rod and selectively driven by the rod. This clamp travels a predetermined distance between a clamping position and a release position, and undergoes rotation over at least part of its stroke. This device further comprises guide members and support elements. These guide members include a guide member fixed relative to the body and a movable guide member linked to the clamp. These fixed and movable guide members cooperate to drive the clamp in a rotational movement about the pivot axis, at least at the end of its stroke towards its position of release and following a translational movement at least at the end of its stroke towards its clamping position. In addition, these support elements include a fixed support element relative to the body and a movable support element linked to the flange, these fixed and movable 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 guiding members, a sliding contact parallel to the translational movement of the flange and allowing the flange to brace against the part to be clamped.

[0005] The device thus described therefore comprises a flange moving from a clamping position to a release position and vice versa by successive and combined translational and rotational movements.

[0006] This clamping device has the advantages of being compact, fast, retractable, powerful, and moreover with a flange that is not very prone to buckling.

[0007] However, despite all these advantages compared to other existing clamping flanges, such a device still has disadvantages.

[0008] 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, and fluids of all kinds can enter.

[0009] This can cause jamming during the operation of the clamping device.

[0010] Protecting the device with a silicone bellows covering the housings, openings, and crevices could be considered, but this compromises the compactness of the clamping device. Furthermore, the complex movement of the clamp prevents proper enclosing with this type of protection. Finally, this type of elastomeric bellows protection can degrade rapidly under the chemical attack of the fluids in contact with it, as well as the exposure to hot chips.

[0011] A second drawback lies in the fact that the device's flange must move rapidly from a relaxed position to a clamped position under the action of a pressurized fluid actuating the cylinder, therefore with a fluid flow fast. But it is also necessary that the flange comes into clamping position on a part to be clamped with sufficient clamping force, but below a determined maximum threshold, for example to avoid the clamping force being damaging to the workpiece, which requires very fine adjustment of the pressure of the pressurized fluid actuating the cylinder, with a slower fluid flow.

[0012] To meet these two requirements, the device must be able to transition from a rapid flow of pressurized fluid to a slower flow and vice versa at a specific time, which can vary depending on the flange and the cylinder stroke. Determining this time involves precisely detecting the position of the device's flange during its stroke as it transitions from the release position to the clamping position of the part being clamped. This can be achieved by equipping the device with a flange displacement detector, but this is an expensive additional piece of equipment that requires a power supply. This hinders the development of a simpler device.

[0013] A third drawback lies in the fact that the device's flange has a nozzle whose flat end is designed to bear against a surface of the workpiece to be clamped. Sometimes, the surface is not parallel to the flat end of the nozzle. In this case, the nozzle's contact with the workpiece is only localized, and the workpiece may slip or the surface may be marked by the nozzle.

[0014] In this context, the invention aims to provide an improved clamping device having in preamble the characteristics of the clamping device described above but free from all or part of the defects previously mentioned.

[0015] To this end, the invention relates to a device for clamping a workpiece onto 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 clamp being articulated about a pivot axis on the rod and selectively driven by the rod, this clamp moving over a predetermined stroke between a clamping position and a release position, and undergoing rotation over at least part of its stroke, 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 movable guide members cooperating to drive the flange in a rotational movement around the pivot axis at least at the end of its stroke towards its release position and in a translational movement at least at the end of its stroke towards its clamping position, and these support members comprising a support member fixed relative to the body and a movable support member linked to the flange, these fixed and movable support members 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 the flange to be braced against the part to be clamped.

[0016] Advantageously, this clamping device includes at least one cover hood 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.

[0017] This makes it possible to offer a clamping device that remains compact while providing simple and economical protection against seizing elements, this protection being able to follow the complex movements of the clamp.

[0018] According to a particular feature of the invention, the first end of the cover(s) comprises two shafts originating from the cover and extending laterally in opposite directions, cooperating by fitting into reciprocal bearings of the flange to form pivoting connection means.

[0019] According to another feature of the invention, the second end of the cover(s) have lateral edges configured to slide in opposite tracks of the body to form translational linking means.

[0020] This proposed protection is simple to mount on the clamping device.

[0021] According to another feature of the invention, at least one cover hood includes an elastically deformable part.

[0022] This allows for even more precise tracking of the bridle's movements.

[0023] According to another feature of the invention, this clamping device includes a cover cover whose elastically deformable part has a non-deformable configuration when the clamp is in the clamping position, and which has a deformed configuration when the clamp is in the release position.

[0024] According to another feature of the invention, this clamping device includes a cover cover whose elastically deformable part has a non-deformable configuration when the clamp is in the relaxed position, and which has a deformed configuration when the clamp is in the tightening position.

[0025] According to yet another feature of the invention, the clamping device includes detection means configured to detect when the flange is in translation only during the movement of the flange from the release position to the clamping position, these detection means including an orifice in the body configured to be closed by the flange during its sliding contact parallel to the translational movement against said body of the device, said orifice being followed by an air supply channel.

[0026] The detection system determines the flange's position by blocking the orifice, which changes the pressure in the air supply channel. A pressure sensor on the channel's supply system detects orifice blockage when the flange moves from the relaxed to the clamped position, provided the flange is in a purely linear motion. This allows the flow rate and pressure of the device's cylinder to be controlled, reducing the fluid flow and enabling fine-tuning of the clamping force. Adjusting the orifice's position along the device body determines the point at which the fluid flow rate is reduced.

[0027] According to yet another feature of the invention, the clamping device comprises two parallel clamps longitudinally and two respective cylinders.

[0028] This allows for clamping in two adjacent areas, and increases the clamping surface of the flange ends over a surface area of part to be flanged. This is especially true if this surface is not parallel to the ends of the flanges.

[0029] According to an alternative or complementary embodiment of the invention, each flange of the clamping device comprises a beak having at its end a flat area pivotally mounted on a ball joint.

[0030] This ensures that the contact of the nozzle of the flange(s) on the surface of the part is made over a surface and not over a line or a point.

[0031] Other objects and advantages of the present invention will become apparent during the following description, which refers to the accompanying drawings illustrating an example of an embodiment and in which:

[0032] [Fig.1] is a front perspective view of a clamping device exhibiting characteristics of a flange and a cylinder known from the state of the art;

[0033] [Fig.2] is a rear perspective view of a clamping device from Figure 1;

[0034] [Fig.3] is a partial cross-sectional view of the device illustrated in figures 1 and 2 but with the flange in the released position, the section being made along a plane parallel to the median plane of this device;

[0035] [Fig.4] is a cross-sectional view of the device illustrated in figures 1 and 2, taken along the median plane of this device;

[0036] [Fig.5] is a front perspective view of a clamping device in the maximum clamping position according to the invention, said device including in particular the characteristics of the flange and the cylinder of the device of figure 1;

[0037] [Fig.6] is a rear perspective view of the clamping device in Figure 5;

[0038] [Fig.7] is a cross-sectional view of the device illustrated in figures 5 and 6, taken along the median plane of this device;

[0039] [Fig.8] is a front perspective view of the clamping device of figure 5 when the clamp is in an intermediate position between the release position and the clamping position, in translation position only;

[0040] [Fig.9] is a rear perspective view of the clamping device in Figure 8;

[0041] [Fig.10] is a cross-sectional view of the device illustrated in figures 8 and 9, taken along the median plane of this device;

[0042] [Fig.11] is a front perspective view of the clamping device of figure 5 when the clamp is in the maximum release position;

[0043] [Fig.12] is a rear perspective view of the clamping device in Figure 11;

[0044] [Fig.13] is a cross-sectional view of the device illustrated in figures 11 and 12, taken along the median plane of this device;

[0045] 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 flange 2. The flange has a beak 20 oriented in a direction referred to as forward when the clamping device D is in the clamping position as illustrated in Figure 5. The clamping device thus has a front and a rear defined by the beak 20. The left side of Figures 4, 7, 10, and 13 is considered to be oriented forward, and the right side is considered to be oriented rearward.

[0046] The operation of the clamping device D with respect to the movement of the flange 2 under the action of the cylinder 1 follows the characteristics described in document EP1697088B1 and reproduced below. Figures 1 to 4 correspond respectively to Figures 1, 2, 4 and 5 of said document EP1697088B1 and depict a clamping device according to the prior art.

[0047] Thus, the cylinder 1 is a double-acting hydraulic cylinder and includes a body 10 fixed in operation to the tooling itself arranged for example in a machining center, and a rod 11 movable relative to the body 10 of this cylinder.

[0048] The cylinder body 10 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 high-pressure hydraulic source while the other is connected to a low-pressure reservoir.

[0049] 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.

[0050] The flange 2 thus moves, 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.

[0051] 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 pressurized fluid into the second chamber 102 of this cylinder 1.

[0052] 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 linked to the flange 2, and the support elements 4 similarly comprising a support element 41 fixed relative to the body 10 and a movable support element 42 linked to the flange 2.

[0053] The fixed and movable guide members, 31 and 32, cooperate to drive the flange 2 in a rotational movement around the pivot axis X at least at the end of the stroke of this flange towards its release position, and to drive the flange 2 in a translational movement at least at the end of the stroke of this flange towards its clamping position.

[0054] For their part, the fixed and mobile support elements, 41 and 42, cooperate, at least at the end of the stroke of the flange 2 towards its clamping position, to offer each other, at a distance from the guide elements 3, a sliding contact parallel to the translational movement of the flange 2 and allowing the flange 2 to be braced on the part to be clamped.

[0055] Advantageously, the rod 11 preferably extends along a translation axis Z which passes between the guide members 3 and the support elements 4.

[0056] Here, the movable guide member 32 comprises a cam formed of two grooves, cut symmetrically in 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 grooves presents a path which continuously approaches the pivot axis X from the first end 321 of this path to its second end 322. This path includes a straight path portion 320r which terminates at the first end 321 and a curved path portion 320c, adjacent to the straight path portion 320r and terminating at the second end 322.

[0057] Figure 3 shows only one cam, the other cam being deduced by symmetry with respect to plane M.

[0058] The fixed guide element 31 consists of a pair of pins or rollers, fixed to the body 10 of the cylinder 1 and respectively engaged in the grooves forming the cam. The body 10 has two pins or rollers 31, one visible in Figure 3, the other being deduced by symmetry with respect to plane M.

[0059] As shown in Figure 3, 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 which the rod 11 makes to drive the flange 2 towards its release position.

[0060] 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.

[0061] 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 rests symmetrically with respect to this same median plane M.

[0062] In the embodiment of the invention illustrated here in the figures, the rod 11 exits the cylinder 1 on the side of its first chamber 101.

[0063] In this case, the fixed guide member 31 and the fixed support element 41 are advantageously supported by a portion 100 of the cylinder body 10, which is shaped like a yoke. The flange 2 is then guided in its median plane M between two parallel, opposing faces, 100a and 100b, belonging to this yoke-shaped portion 100. This embodiment allows a significant rotation of the flange 2 between its clamping and release positions, typically a rotation of 90 degrees or more.

[0064] In addition to the elements described above, the clamping device D includes at least one cover cap 5, for example in the form of a plate having two ends 50, 51 and two lateral 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 a yoke, and perpendicular to these faces.

[0065] The at least one cover 5 includes a first end 50 towards flange 2. This first end 50 cooperates with this flange via a pivot joint, also known as a pivot joint. To achieve this, the at least one cover 5 comprises two shafts carried by the same virtual axis of rotation parallel to the pivot axis X. These two shafts originate from the first end 50 of the cover 5 and extend in opposite directions. These shafts cooperate by fitting into reciprocal bearings machined into the flange 2. The bearings and the shafts form pivot joint means between the at least one cover 5 and the flange 2.

[0066] Of course, other embodiments of a pivot joint can be envisaged in the spirit of the invention.

[0067] The at least one cover cap 5 includes 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 joint, also called a translational joint. In fact, the two parallel faces 100a and 100b, belonging to part 100, have grooves forming slides in which the lateral edges 52 slide. The slides and edges form sliding connection means.

[0068] Of course, here too other embodiments of a pivot joint can be envisaged in the spirit of the invention.

[0069] The at least one cover hood 5 may also include an elastically deformable zone 53, in particular under the action of a force whose vector is parallel to the median plane M.

[0070] According to an embodiment of the invention illustrated in Figures 5 to 13, the clamping device D comprises a front cover cover 5a on the front of the clamping device D as particularly illustrated in Figures 5, 8 and 11, and it includes a rear cover 5b on the rear of the clamping device D, as particularly illustrated in Figures 6, 9, and 12. The cross-sectional views in Figures 7, 10, and 13 allow the front cover 5a and rear cover 5b to be shown simultaneously in the same figures. These cross-sectional views also clearly distinguish the deformation zones 53 of the cover caps 5a and 5b. As can be seen in these figures, the elastically deformable portion 53 of the front cover 5a is not deformed when the clamp 2 is in the clamping position, and it is deformed when the clamp 2 is in the loosening position. Conversely, the elastically deformable portion 53 of the rear cover 5b is not deformed when the clamp 2 is in the loosening position, and it is deformed when the clamp 2 is in the clamping position.Thus the hoods follow the complex movement of the flange 2 to protect the mechanisms of this clamping device D in a simple and compact way.

[0071] Each cover cover 5a, 5b is preferably but optionally made of metallic material, in particular steel.

[0072] According to a particular embodiment of the invention, the fixed support element 41 of the clamping device D has an orifice 6 on its surface against which the movable support element 42 of the clamp 2 slides. This orifice 6 is followed by an air supply channel. Air is blown through this channel and this orifice 6.

[0073] When the movable support element 42 closes the hole 6 by sliding against the fixed element 41, an increase in the pressure of the air blown into the now-closed orifice 6 can be detected. This indicates that the flange 2 has completed its pivoting and is entering its translational phase to come into contact with the workpiece to be clamped, subsequently clamping itself against it. The flow rate of the fluid supplying the cylinder 1 of the clamping device D can then be reduced to finely adjust the descent of the flange 2 and the clamping force.

[0074] This provides inexpensive and simple means of detecting when the flange is in translation only during its movement from the release position to the clamping position. These detection means include, among other things, orifice 6.

[0075] A second opening in the upper part of the body, also connected to the channel, advantageously prevents the air supply channel from being completely blocked.

[0076] According to yet another particular embodiment of the invention, not illustrated here, the clamping device comprises two parallel flanges oriented longitudinally in a front / rear direction. Each flange is actuated by a corresponding cylinder. Each flange may include a single roller or pin moving within a cam. The device may also include a central plate supported by the median plane M in which two cams are placed and in which rollers or pins attached to only one of the flanges 2 act independently.

[0077] According to another particular embodiment of the invention, not illustrated here, the nozzle 20 of the flange 2 comprises a movable element with a ball joint at its end, configured to be interposed between the nozzle 20 and a part to be flanged. This movable element comprises, on the one hand, a ball joint that fits into a housing corresponding to the end of the nozzle 20, and on the other hand, a flat area configured to be aligned with and in contact with a part to be flanged. This embodiment can, of course, be applied to both flanges 2 of the device described in the preceding paragraph.

[0078] This results in a compact, robust D-type clamping device that is more resistant to environmental stresses. Its lifespan is thus improved and its maintenance reduced.

[0079] Adjusting the descent of flange 2 towards its clamping position can be done at suitable speeds, at little cost and by means not requiring significant maintenance.

[0080] In addition, this clamping device also ensures better support of the parts to be clamped and limits the creation of clamping marks on the part to be clamped.

Claims

Demands

1. A clamping device (D) for a workpiece on a tool, comprising a cylinder (1) and a clamp (2), the cylinder (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 clamp (2) being articulated about a pivot axis (X) on the rod (11) and selectively driven by the rod (11), this clamp (2) moving over a determined stroke between a clamping position and a release position, and undergoing rotation over at least part of its stroke, this clamping device (D) further comprising guide members (3) and support elements (4), these guide members (3) comprising a guide member fixed (31) relative to the body (10) and a movable guide member (32) linked to the clamp (2). ,these fixed and movable guide members cooperating to drive the flange (2) in a rotational movement about the pivot axis (X) at least at the end of its stroke towards its release position and in a translational movement at least at the end of its stroke towards its clamping position, and these support elements (4) comprising a fixed support element (41) relative to the body (10) and a movable support element (42) linked to the flange (2), these fixed and movable support elements cooperating selectively, at least at the end of the stroke of 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 the flange (2) to be braced against 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 flange (2) by a pivoting joint, a second end (51) cooperating with the body (10) by a translational joint.

2. Clamping device (D) according to claim 1, characterized in that the first end (50) of the cover(s) (5, 5a, 5b) has two shafts originating from the cover (5, 5a, 5b) and extending laterally in opposite directions, these shafts cooperating by fitting into reciprocal bearings of the flange (2) to form pivoting connection means.

3. Clamping device (D) according to any one of the preceding claims, characterized in that the cover cap(s) (5, 5a, 5b) have lateral edges (52) configured to slide in opposite channels of the body (10) to form translational connecting means.

4. Clamping device (D) according to any one of the preceding claims, characterized in that at least one cover hood (5, 5a, 5b) comprises an elastically deformable part (53).

5. Clamping device (D) according to claim 4, characterized in that it comprises a cover hood (5a) the elastically deformable part (53) of which has a non-deformable configuration when the clamp (2) is in the clamping position, and which has a deformed configuration when the clamp (2) is in the release position.

6. Clamping device (D) according to claim 4 or claim 5, characterized in that it comprises a cover hood (5b) the elastically deformable part of which (53) has a non-deformable configuration when the clamp (2) is in the clamping position, and which has a deformed configuration when the clamp (2) is in the release position.

7. Clamping device (D) according to any one of the preceding claims, characterized in that it comprises detection means configured to detect when the flange (2) is in translation only during the movement of the flange (2) from the release position to the clamping 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 said body (2) of the clamping device (D), said orifice (6) being followed by an air supply channel.

8. Clamping device (D) according to any one of the preceding claims, characterized in that it comprises two parallel flanges (2) longitudinally and two respective cylinders (1).

9. Clamping device (D) according to any one of claims 1 to 7, characterized in that the flange (2) of the clamping device (D) comprises a spout (20) having at its end a flat area pivotally mounted on a ball joint.