Device for clamping a workpiece on a tool

Abstract

A device for clamping a workpiece on tool includes a ram and a clamp, the ram being selectively actuated by a pressurized fluid. The ram includes a body which, when in use, is secured to the tool and a slide mounted such that it can slide with respect to the body. The clamp is hinged with the slide about a pivot axis. The body includes a front face beyond which the clamp projects when it is in a clamping position in order to clamp the workpiece. In addition, the clamp has a release position which it reaches at least partially by pivoting about the pivot axis. The slide includes a piston and a rod that are assembled to one another. The pivot axis is offset by a predetermined distance with respect to the axis of the rod in the direction of the front face.

Claims

1. A clamping device for clamping a workpiece on a tool, the device comprising: a body comprising a front face and a lower portion fixed to the tool when operating; a cylinder having an axis directed along direction and being disposed within the lower portion; a slide that is slidably mounted relative to the body and movable along the axis of the cylinder, wherein the slide comprises a piston and a rod joined by assembly; a flange hinged about a pivot axis on the slide to move from a clamping position to a release position, wherein the pivot axis is offset by a predetermined distance relative to an axis of the rod in a second direction of the front face; a groove in the body; and a finger extending from and directly attached to the flange and through the groove and cooperating to drive the flange in a rotational movement about the pivot axis at least to completion of travel towards the release position and through a translation movement at least to completion of travel towards the clamping position, wherein translational movement of the finger within the groove causes the flange to pivot about the pivot axis towards the clamping position, the groove enclosing the finger and comprising a first portion and a second portion, the first portion being parallel to the axis of the cylinder and the second portion being substantially perpendicular to the first portion; wherein when the flange is in the clamping position, (i) the workpiece can be clamped between the flange and the tool and (ii) the flange is substantially perpendicular to and projects beyond the front face, and when the flange is in the release position, the flange points substantially along the direction of the axis of the cylinder.

2. The clamping device according to claim 1, wherein the groove extends according to a trajectory where the first portion is parallel to a direction of translation of the flange and the second portion is oriented obliquely relative to the first portion, the finger being located in the first portion when the flange is in or near the clamping position and in the second portion when the flange is driven to pivot.

3. The clamping device according to claim 1, wherein the finger is located at a distance from the pivot axis, away in a direction of translation of the rod from the clamping position to the release position.

4. The clamping device according to claim 1 wherein the piston and the rod are assembled by screwing into each other.

5. The clamping device according to claim 1, wherein the body comprises a cap for closing a cylinder chamber delimited by the piston and a bore of the body wherein the piston slides.

6. The clamping device according to claim 1, further comprising upper support elements that each comprise a fixed upper support element, fixed relative to the body, and a mobile upper support element connected to the flange, the fixed and mobile upper support elements cooperating, at least to completion of travel of the flange towards the clamping position, to mutually provide sliding contact parallel to the translation movement of the flange and oppose pivoting of the flange towards the release position.

7. The clamping device according to claim 1, further comprising lower support elements that each comprise a lower fixed support element, fixed relative to the body, and a lower mobile support element connected to a rod, the fixed and mobile lower support elements cooperating, at least on completion of travel of the flange towards the clamping position, to mutually provide sliding contact parallel to the translation movement of the flange.

8. The clamping device according to claim 1, further comprising a detection conduit terminating on a fixed upper support element and configured to connect in fluid communication with a device for detecting a fluid leak.

9. A method for mounting a clamping device, wherein the clamping device comprises: a body comprising a front face and a lower portion fixed to the tool when operating; a cylinder having an axis directed along a direction and being disposed within the lower portion; a slide that is slidably mounted relative to the body and movable along the axis of the cylinder, wherein the slide comprises a piston and a rod joined by assembly; a flange hinged about a pivot axis on the slide to move from a clamping position to a release position, wherein the pivot axis is offset by a predetermined distance relative, to an axis of the rod in a second direction of the front face; a groove in the body; and a finger extending from and directly attached to the flange and through the groove and cooperating to drive the flange in a rotational movement about the pivot axis at least to completion of travel towards the release position and through a translation movement at least to completion of travel towards the clamping position, wherein translational movement of the finger within the groove causes the flange to pivot about the pivot axis towards the clamping position, the groove enclosing the finger and comprising a first portion and a second portion, the first portion being parallel to the axis of the cylinder and the second portion being substantially perpendicular to the first portion; wherein when the flange is in the clamping position, (i) the workpiece can be clamped between the flange and the tool and (ii) the flange is substantially perpendicular to and projects beyond the front face, and when the flange is in the release position, the flange points substantially along the direction of the axis of the cylinder; the method comprising: placing the rod on the body to have it terminate in the body, and assembling the piston on a terminating part of the rod.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood and other particular features and advantages will emerge from the following description, the description making reference to the appended drawings, in which:

(2) FIG. 1 is a perspective view of the clamping device according to a first embodiment of the invention, in gripping position;

(3) FIG. 2 is a view similar to FIG. 1, in a release position;

(4) FIG. 3 is a plan view of the device of FIG. 1;

(5) FIG. 4 is a side elevation of the device of FIG. 1, in an intermediate position between the gripping position and the release position;

(6) FIG. 5 is a view of the detail V of FIG. 4, the device being in the gripping position;

(7) FIG. 6 is a sectional view of the device according to a longitudinal plane in gripping position;

(8) FIG. 7 is a view similar to FIG. 6, in the release position;

(9) FIG. 8 is a view of the detail VIII of FIG. 4;

(10) FIG. 9 is a view similar to FIG. 6 of a flange according to a second embodiment of the invention.

DETAILED DESCRIPTION

(11) A clamping device according to a first embodiment of the invention is intended to clamp a workpiece on a tool. The device comprises a body 1 fixed on the tool, for example by means of a collar 10 screwed onto the tool. The body 1 essentially comprises a cylindrical part 11 to one side of the collar 10, and a part in the form of a clevis 12 opposite the cylindrical part 11. Arbitrarily and for clearer description, it is considered that the bottom of the device is the cylindrical part 11 and the top is the clevis 12. However, the device can be mounted on the tool in any orientation.

(12) The clamping device also comprises a flange 2 mounted mobile between two wings 120 of the clevis 12. The flange 2 comprises an arm 20 at the end of which a support point is intended to clamp the workpiece. The flange 2 has a gripping position in which it projects beyond a front face 13 of the body 1 and in which it is likely to clamp the workpiece on the tool, as shown in FIGS. 1, 4 and 6. It also has a release position in which the front face 13 is totally released upwards and the arm 20 is raised, as shown in particular in FIGS. 2 and 7. The flange 2 projects upwards.

(13) A cylinder 3 is housed in the cylindrical part 11. It comprises a bore 31 made in the body 1 and in which a slide 32 is mounted to slide. A cap 33 blocks the bore 31 by being screwed onto the exterior of the cylindrical part 11 of the body 1. The slide 32 is divided into two parts joined together: a piston 321 and a rod 322. The piston 321 has the form of a disc from which a threaded part projects 3210 placed at the centre of the disc. The rod 322 comprises a threaded muff 3221, followed by a smooth part 3222 then a foot 3223 wider than the smooth part 3222. The smooth part 3222 is adjusted to slide in a neck 14 of the body 1, succeeding the bore 31, whereas the foot 3223 is located beyond the neck 14, in the space between the wings 120 of the clevis 12. The threaded part 3210 is screwed into the muff 3221 of the rod 322. A first chamber 35 is delimited in the bore 31 between the piston 321 and the cap 33 while a second chamber 36 is delimited between said piston 321 and the neck 14. On the outside the cylindrical part 11 comprises two shallow distribution throats 113, 114. Each distribution throat 113, 114 is in communication with one of the chambers 35, 36 of the cylinder 3 by means a respective supply conduit 1130, 1140. Sealing throats are provided on either side of the distribution throats to insulate the latter when the body 1 of the device is placed in a cylindrical housing of the tool, not shown here. Two channels are to be provided terminating in the housing opposite the distribution throats to supply the cylinder 3 with pressurised fluid such as oil or air via the distribution throats 113, 114 and the supply conduits 1130, 1140.

(14) The flange 2 is hinged about a pivot axis A on the foot 3223 of the slide 32. Due to the form of the foot 3223, it is possible to offset the pivot axis A relative to the axis of the slide 32 such that the latter is for example offset in the direction of the front face 13 by a value close to the radius of the smooth part 3222 of the rod 322. The flange 2 reaches the release position by pivoting about the pivot axis A. The movement of the flange 2 also comprises a sliding phase given by the sliding of the piston 321. The flange 2 comprises a flange clevis 21 comprising two wings 210 which enclose the foot 3223. The pivot axis A is made by a trunnion 22 passing through the wings 210 of the flange clevis 21 and the foot 3223.

(15) The device comprises guide members which comprise a fixed guide member 15 relative to the body 1 and a mobile guide member 16 connected to the flange 2 cooperating together to cause pivoting of the flange 2 about the pivot axis A to completion of travel towards the release position. The guide members 15, 16 also impose translation movement to completion of travel towards the gripping position.

(16) The fixed guide member 15 is formed by two grooves 150 made respectively in the wings 120 of the clevis 12 passing through. The groove 150 extends according to a trajectory whereof a first portion 1501 is parallel to the direction of translation of the flange 2 and a second portion 1502 is oriented obliquely relative to the first portion 1501, practically at 90. The second portion 1502 is oriented towards the rear, opposite the front face 13. The two portions are connected by a curved portion. The groove 150 is extended downwards to create a passage 1503 opposite the pivot axis A when the flange 2 is in gripping position. This passage enables introduction of the trunnion 22 during assembly of the device.

(17) The mobile guide member is a finger 16 in the form of a nipple. In practice, the nipple 16 is screwed onto the flange 2 and comprises a cylindrical head of diameter adjusted to the width of the groove 150. The nipple 16 is placed above the pivot axis A.

(18) The clamping device comprises also upper support elements 4 and lower support elements 5. The upper support elements 4 comprise an upper fixed support element 41, fixed relative to the body 1, and a mobile upper support element 42 connected to the flange 2. The upper fixed support element 41 is formed by two support surfaces substantially vertical in front of the wings 120 of the clevis 12. The mobile upper support element 42 comprises two stubs projecting from the faces of the flange 2 and offering two vertical support surfaces when the flange 2 is in gripping position. In this way, the upper fixed and mobile support elements 41, 42 cooperate to completion of travel of the flange 2 towards the gripping position to mutually offer sliding contact parallel to the translation movement of the flange 2 and oppose pivoting of the flange 2 towards the release position.

(19) The lower support elements 5 comprise a lower fixed support element 51, fixed relative to the body 1, and a lower mobile support element 52 connected to the rod 322. The lower fixed support element 51 has the form of a groove placed along the foot 3223 of the rod 322 between the wings 210 of the flange clevis 21. The lower mobile support element 52 comprises a support surface borne by the foot 3223 opposite the groove 51. The fixed and mobile lower support elements 51, 52 cooperate to completion of travel of the flange 2 towards the gripping position to mutually offer sliding contact parallel to the translation movement of the flange 2. In cooperation with the upper support elements 4, the flange 2 is retained very rigidly when it is placed supported against a workpiece to be clamped, with support planes which opposing the torque generated by contact with the flange 2 on the workpiece in front of the device.

(20) A detection conduit 19 is provided terminating on the upper fixed support element 41, as shown in FIG. 5, and intended to be connected in fluid communication with a device for detecting a fluid leak. For this, the detection conduit 19 comprises a joining section terminating in a detection throat 115, between the collar 10 and the sealing throat closest to the collar 10. The mobile upper support element comprises an indentation which is opposite the output of the detection conduit 19 when the flange has completed travel towards the gripping position. It could therefore be considered that the flange has not been stopped by the workpiece to be clamped, and therefore the workpiece is absent in this position.

Operation of the Device

(21) It is supposed that the device is initially in the gripping position, as shown in FIG. 1. The piston 321 is towards the bottom such that the first chamber 35 has reduced volume. With the flange 2 placed at the very bottom, the fixed and mobile support elements are in contact with each other. The flange 2 is oriented to project beyond the front face 13.

(22) The flange 2 is actuated by sending pressurised fluid to the first chamber 35. The fluid of the second chamber 36 escapes and lets the piston 321 rise. The flange 2, driven by the foot 3223, also rises with a translation movement, guided also by the finger 16 which circulates in the first portion 1501 of the grooves 150. When the finger 16 arrives at the end of the first portion 1501, the upper support elements 4 are released from each other. The finger releases in the second portion 1502 of the groove 150, causing pivoting of the flange 2 about the pivot axis A on the foot 3223 of the cylinder 3 in the direction of arrow F1. The upper mobile support element passes over the clevis 12. The flange 2 then reaches the release position in which it does not project beyond the front face 13, but in which the arm 20 is placed above the clevis 12 pointing upwards. The space before the device is released to remove a workpiece and put one in place.

(23) To achieve clamping of the workpiece, the cylinder 3 is controlled in the reverse direction, that is, the pressurised fluid is sent to the second chamber 36 and allows it to escape from the first chamber 35. The piston 321 commences displacement downwards. The finger 16 is forced to traverse the groove 150 in the second portion 1502, causing pivoting of the flange 2 in reverse of arrow F1, that is, towards lowering of the arm 20 above the workpiece beyond the front face 13. When the finger reaches the first portion 1501 of the groove 150, the piston 321 continues its sliding course by driving the flange 2 downwards. The upper support elements engage by being opposite. When the arm 20 comes into contact with the workpiece at the level of the support point and exerts clamping force on it, the flange 2 is supported against the clevis 12 at the level of the upper support elements 4. It also tends to press the rod 322 of the cylinder 3 against the groove at the level of the lower support elements 5. The flange 2 is held supported rigidly on the workpiece.

(24) According to a second embodiment, shown in FIG. 9, a clamping device is distinguished from the device according to the first embodiment in that the slide 32 is made in a single workpiece comprising the rod 322 and the piston 321.

(25) To install such a device, the rod 322 of the slide is introduced into the neck 14 by passing it through the chamber of the cylinder. The trunnion 22 id then put in place to assemble the rod 322 with the flange 2. The cap 33 is screwed onto the body 1 to close the chamber 35 of the cylinder. The operation of the device is the same as for the first embodiment.

(26) The invention is not limited to the embodiments described above.