FR2987294A1 - Clamping device for clamping workpiece i.e. lengthened rod, on gripper carrier system of e.g. transfer machine, has push rod pushing clamping jaws towards workpiece during axial displacement of casing with regard to head part holder - Google Patents

Abstract

The device has a tubular casing (1) that is ready to be held in axial translation on a frame of a transfer machine. A workpiece (4) i.e. lengthened rod, is actuated by a relative axial displacement of the casing with regard to an axially fixed thrust (3). A head part holder (5) is movable in translation with regard to the casing. The head part holder is ready to receive and support the workpiece. A push rod (8) arranged interdependent of the casing pushes clamping jaws (6) towards the workpiece during an axial displacement of the casing with regard to the head part holder.

Description

The present invention relates to means for clamping and holding a workpiece on a machining tool gripper system. Numerous machining machines, such as turning machines or transfer machines, comprise a gripper holder for receiving and actuating a centrally located gripper into which a portion of a workpiece can be engaged. machined. An example of such a clamp engaged in a clamp holder pin is shown in longitudinal section in Figure 1 attached to this patent application. The collet holder 1 is capable of being held in axial translation along its proximal end section 1a on the frame of a transfer machine or on the spindle of a turning or milling machine. The body of the gripper holder 1 is generally tubular, with an axial passage li in which a gripper 2 engages. The distal end portion 1b of the gripper holder 1 comprises a conical inner bearing 1c 15 on which engages a corresponding conical outer surface 2a of the clamp 2. The clamp 2 comprises a front face 2b bearing axially against a stop or cap 3 which is itself fixed in axial translation on the frame of the machine-transfer or on the spindle of turning or milling machine. The clamp 2 comprises an axial passage 2c, and longitudinal slots 2d allowing the spacing or the approximation of the wall of the clamp 2 around the axial passage 2c, for the clamping or loosening of a workpiece engaged in said axial passage 2c. The clamping of the workpiece is obtained by axial thrust of the clamp holder 1 in the direction of the cup 3. A clearance of the workpiece is obtained by axial withdrawal of the clamp holder sleeve 1 away from the The embodiment illustrated in FIG. 1 relates to a clip which clamps a piece radially from the outside to the inside. There are also known clamps capable of radially clamping a piece from the inside to the outside.

These clamps function perfectly when the workpieces have circular or substantially circular cross-sectional shapes. But a first problem is that these clamps do not properly tighten the workpieces that have shapes deviating from a circular cross section.

A second difficulty is that these clamps require the engagement of a relatively long section of the workpiece, within the clamp, and this engaged section can not be machined otherwise than by a subsequent recovery.

As a result, many parts can not be machined entirely on a transfer machine or a turning or milling machine other than by fitting added clamping devices, which are added to the outside of the machine. the clamp holder, and which are therefore very bulky and hinder the approach of the tools. The problem proposed by the present invention is therefore to allow the holding of workpieces on a clamping machine tool holder system, without increasing the size beyond the usual size of a clamp holder socket, by allowing the holding of parts whose shapes do not necessarily have a circular section, and allowing a more complete machining parts without recovery on another machine. To achieve these and other objects, the invention provides a workpiece clamp for clamping a workpiece to a machining tool clamping system, comprising a socket capable of being machined. held in axial translation on the frame of a transfer machine or on the spindle of a turning or milling machine, and comprising workpiece holding and clamping means actuated by a relative axial displacement of the sleeve by relative to an axially fixed stop; according to the invention, the device comprises: - a workpiece head, driven in rotation by the sleeve, movable in translation relative to the sleeve, fixedly held in translation relative to the spindle of a turning or milling machine, or machine-transfer frame, and adapted to receive and support the workpiece, - at least one piece clamping jaw, rotatably mounted on the workpiece head, and adapted to clamp the workpiece on the workpiece head - A pusher, integral with the sleeve, and pushing the jaw towards the workpiece during an axial displacement of the sleeve relative to the workpiece head. In this way, the clamping maneuver can be performed in the same way as in the known clamps, namely by axial displacement of the sleeve, and the clamping is obtained without increasing the size of the standard clamp. Preferably, the device comprises two jaws in opposition, biased towards one another by the pusher. The pusher, which is itself guided in the workpiece head, effectively determines the position of the workpiece by the force transmitted to the workpiece by the jaws. According to an advantageous embodiment, the jaws are sectors of cylinder, limited by a longitudinal edge of support and a longitudinal edge of the clamping, the longitudinal edge of support being shaped according to a profile of the piece to machining, the longitudinal clamping wedge forming oblique clamping ramp cooperating with the pusher, the jaws being mounted displaceably in axial rotation around a longitudinal axis of the workhead in a housing in interrupted cylinder sector with a longitudinal axis of the head-piece. The rotational movement of the jaws in a cylinder sector housing of the workpiece head achieves excellent clamping while minimizing the size of the clamping device. According to an advantageous embodiment, the workpiece head has a bearing surface shaped to receive the workpiece, in an area where the housing receiving the jaws is interrupted. In this way, the strength of the workpiece is optimized in three faces, namely the two faces against which the jaws bear, and the face resting on the bearing surface. The workpiece can thus be effectively held over a great length, and none of its sections is obscured for machining. In practice, it may advantageously be provided that the workpiece head has an insert support, forming the workpiece support surface, forming the inner surface of the housing containing the jaws, and guiding the pusher in its axial displacement.

This device can thus be produced economically. Preferably, it is provided that the device comprises return springs ensuring the return of the jaws relative to each other in the open position. It can be traction springs, engaged between the longitudinal edges of clamping jaws.

Preferably, it is also possible for the workpiece head to be pushed axially away from the bushing by elastic means, and remains in axial abutment against the axially fixed abutment. In this way, the piece is held in a determined manner in axial position. On the jaws, the longitudinal clamping edges may advantageously be plane and oblique, and the pusher may comprise oblique corresponding corner clamping faces. The realization is simplified. However, it is found that such clamping faces and longitudinal edges of clamping can not be supported on their entire surface in all the angular positions of the jaws.

Preferably, it can be provided that, in the clamping position, the clamping faces of the pusher bear against their entire surface against the longitudinal edges of the clamping jaws.

6055FDEP.docx 2987294 4 The structure of the pusher inside the clamp-holder socket makes it possible to envisage the reservation of a channel for conduction of fluid under pressure, making it possible to bring fluid under pressure from the machine-transfer frame. or the spindle of a turning or milling machine, and to project this fluid onto the surfaces intended to receive and clamp the workpiece on the workhead. This allows the machining debris to be removed from the previous parts to ensure reliable positioning of a new workpiece. Other objects, features and advantages of the present invention will become apparent from the following description of particular embodiments, with reference to the accompanying drawings, in which: FIG. 1 is a longitudinal sectional view of a device of FIG. workpiece holding of the prior art, with radial clamping pliers; - Figure 2 is a longitudinal sectional view of a workpiece clamping device according to the present invention in part release position; FIG. 3 is a cross-section along the sectional plane A-A of the device of FIG. 2, in the same position; - Figure 4 is a longitudinal section of the device of Figure 2, in the work clamping position; - Figure 5 is a cross section along the section plane B - B of the device 20 of Figure 4; and FIG. 6 is a perspective view from below of the device of FIGS. 2 to 5, the outer part of the workpiece head having been removed to reveal the jaws and the return springs. In the embodiment illustrated in FIGS. 2 to 6, a workpiece clamping device comprises a tubular bush 1, the proximal end portion 1a of which is adapted to be held in axial translation on the frame of FIG. a machine-transfer or on the spindle of a turning or milling machine. The device further comprises means for holding and clamping a workpiece 4. In the example shown, the workpiece 4 is an elongated rod, with a slightly bulged end 4a, and with a second end 4b curved in L and having an outgrowth 4c, the assembly being able to constitute a gripping arm for a pen.

The holding and clamping means of the workpiece 4 are actuated by a relative axial translational movement of the sleeve 1 relative to an axially fixed abutment 3.

According to the invention, the holding and clamping means of the workpiece 4 comprise a workhead 5, two clamping jaws 6 and 7 (FIGS. 3 and 5), and a pusher 8. The workpiece head 5 comprises a tubular proximal section 5a, slidably engaged in the distal end portion 1b of the sleeve 1, and comprises a tubular sector open tubular distal section 5b with a peripheral wall 5c and a core central 5d. The peripheral wall 5c and the central core 5d provide a housing 5e generally in the cylinder sector, interrupted upwards in FIG. 5 due to the interruption of the peripheral wall 5c, and 10 having a longitudinal axis. In the embodiment illustrated, the peripheral wall has a constant thickness, and the central core has a cylindrical outer face concentric with the peripheral wall 5c, so that the housing 5e is also concentric with the peripheral wall 5c.

The jaws 6 and 7, as illustrated in Figure 5, are cylinder sectors, limited by a longitudinal support edge, respectively 6a and 7a, and a longitudinal clamping edge, respectively 6b and 7b. The longitudinal support edge 6a or 7a is shaped according to a profile of the workpiece 4, so as to cover a large length of a side face 20 of the workpiece 4. The jaws 6 and 7 being in opposition the piece 4 is thus held by its two opposite lateral faces. The longitudinal tightening edge 6b or 7b cooperates with the pusher 8 which engages at the corner between the jaws 6 and 7. The central core 5d of the workpiece head 5 comprises a bearing surface 25f which is shaped to receive the workpiece 4 according to its underside, providing a stable and reliable support. Preferably, the bearing surface 5f has the same longitudinal and transverse profile as the lower face of the workpiece 4. In practice, to ensure a good ease of manufacture of the tooling, the central core 5d may be a insert on the workpiece head 5, as shown in the figures, the assembly being effected by screws such as the screw 5g. The pusher 8 comprises a proximal section 8a which is engaged inside the sleeve 1 and inside the proximal section 5a of the workpiece head 5, and which is fixed by a screw 9 to the sleeve 1.

The proximal portion 8a of the pusher 8 has a shoulder 8b against which a compression spring 16 is engaged between this shoulder 8b and the proximal section 5a of the workhead 5, to push back the head-holder. 5 and hold it permanently in abutment against the axially fixed abutment 3. The pusher 8 comprises a distal section 8c having a plane upper face 8d sliding under the central core 5d as illustrated in FIGS. 3 and 5, having a peripheral surface cylindrical 8th sliding in the peripheral wall 5c of the workpiece head 5, and having two clamping faces 8f and 8g whose spacing is reduced as one approaches the distal end 8h of the pusher 8, thus forming oblique wedge clamp faces. In this way, the central core 5d is an insert support, which forms the bearing surface 5f of the workpiece 4, which forms the inner surface of the housing 5e containing the jaws 6 and 7, and which guides the push 8 in its axial translation. As can be seen in FIG. 6, the jaws 6 and 7 are biased by two traction springs 10 and 11 which tend to bring their longitudinal tightening edges 6b and 7b closer to one another so as to spread the jaws 6 and 7 vis-à-vis the workpiece 4. The springs 10 and 11 are engaged in appropriate peripheral grooves 12 and 13 of the pusher 8 (Figure 2). The operation of this device is explained below. In the position illustrated in Figures 2 and 3, the device is in the loosened state, in which the jaws 6 and 7 are away from the workpiece 4, the pusher 8 is moved axially with the sleeve 1 relative to the workpiece head 5. This position allows the loading or unloading of workpiece. It should be noted that, in this position, in FIG. 3, the clamping faces 8f and 8g of the pusher 8 bear only part of their surface 25 against the respective longitudinal clamping edges 6b and 7b of the jaws 6 and 7. This support partial is not a disadvantage, since no effort must be applied between the corresponding surfaces in this loose state. By axial displacement D (FIG. 6) of the bushing 1 and of the pusher 8 in the direction of the workpiece holding head 5, the pusher 8 is forced between the jaws 6 and 7 to the clamping position illustrated in FIGS. 5. In this movement, the oblique wedge faces 8f and 8g of the pusher 8 force the respective rotation R6 and R7 (Figure 3) of the jaws 6 and 7 in the housing 5e until the longitudinal support songs 6a and 7a strongly tighten the lateral faces of the workpiece 4. In this position, as illustrated in FIG. 5, the clamping faces 8f and 8g of the pusher 8 bear against their entire surface against the longitudinal edges of the workpiece. clamping 6b and 7b jaws 6 and 7, ensuring a good distribution of clamping forces.

Subsequently, by withdrawal of the pusher 8 in the opposite direction of the axial displacement D (FIG. 6), the jaws 6 and 7 which are biased in the released position as illustrated in FIGS. springs 10 and 11 (FIG. 6) to release the machined part 4.

In the embodiment which has been illustrated in the figures, the workpiece 4 is clamped by two jaws 6 and 7 in opposition. One could conceive, according to a simplified embodiment of the invention, that one of the two jaws 6 or 7 is fixed, the other jaw being only mobile in rotation and biased by the pusher 8.

It is also conceivable that the central core 5d is not coaxial with the outer peripheral wall face 5c. It will be understood that the bearing surface 5f and the longitudinal supporting edges 6a and 7a which abut against the workpiece 4 should preferably be shaped to apply correctly over the entire surface of the workpiece 4. central core 5d and the jaws 6 and 7 thus constitute tools that are adapted in shape according to the workpiece 4. According to an advantageous embodiment, there is further provided fluid ejection means for cleaning the zone of the workpiece head 5 receiving the workpiece 4, to eliminate any risk of remanence of waste previously machined parts 20. It is indeed necessary that the area of the workpiece head 5 to receive the workpiece 4 is clean, to ensure proper positioning of the workpiece 4 brought by an automatic system. For this, as illustrated in FIG. 2, the screw 9 for fastening the pusher 8 in the sleeve 1 has a central channel 9a, which continues with an axial channel 8i in the pusher 8 to open into a radial chamber 14 which even by an axial passage 15 to the zone occupied by the workpiece 4. Thus, a fluid coming from the machine can be ejected by the axial passage 15 longitudinally on the surfaces of the zone intended to be subsequently occupied by the workpiece 4, that is to say on the longitudinal support edges 6a, 7a and on the bearing surface 5f, these same surfaces being intended to receive and clamp the workpiece 4 on the head The present invention is not limited to the embodiments that have been explicitly described, but it includes the various variants and generalizations thereof within the scope of the claims hereinafter.

6055FDEP.docx

Claims (10)

CLAIMS1 - Workpiece clamping device, for clamping a workpiece (4) on a clamping machine tool holder system, comprising a sleeve (1) adapted to be held in axial translation on the frame of a transfer machine or on the spindle of a turning or milling machine, and comprising workpiece holding and clamping means actuated by a relative axial displacement of the sleeve (1) with respect to a stop axially fixed (3), characterized in that it comprises: - a workhead (5) driven in rotation by the sleeve (1), movable in translation relative to the sleeve (1), held fixed in translation relative to the spindle of a turning or milling machine or to the machine-transfer frame, and adapted to receive and support the workpiece (4), - at least one workpiece jaw (6, 7) mounted rotating (R6, R7) on the work head (5), and able to clamp the workpiece (4) on the head workpiece holder (5), - a pusher (8), integral with the sleeve (1), and pushing the jaw (6, 7) towards the workpiece (4) during an axial displacement (D) of the sleeve (1) relative to the workhead (5). 2 - Workpiece clamping device according to claim 1, characterized in that it comprises two jaws (6, 7) in opposition, biased towards one another by the pusher (8). 3 - Workpiece clamping device according to claim 2, characterized in that the jaws (6, 7) are cylinder sectors, limited by a longitudinal bearing edge (6a, 7a) and a longitudinal clamping edge (6b, 7b), the longitudinal bearing edge (6a, 7a) being shaped according to a profile of the workpiece (4), the longitudinal tightening edge (6b, 7b) forming oblique clamping ramp cooperating with the pusher (8), the jaws (6, 7) being mounted displaceably in axial rotation (R6, R7) about a longitudinal axis of the workpiece head (5) in a housing (5e) in an interrupted cylinder sector with an axis longitudinal axis of the workhead (5). 4 - Workpiece clamping device according to claim 3, characterized in that the workpiece head (5) has a bearing surface (5f) shaped to receive the workpiece (4), in a zone wherein the housing (5e) receiving the jaws (6, 7) is interrupted. 5 - Workpiece clamping device according to one of claims 3 or 4, characterized in that the workpiece head (5) comprises an insert piece support (5d), forming the bearing surface (5f) of part, forming the inner surface 6055FDEP.docx 2987294 9 housing (5e) containing the jaws (6, 7), and guiding the pusher (8) in its axial displacement (D). 6 - Workpiece clamping device according to any one of claims 3 to 5, characterized in that it comprises return springs (10, 11) for restoring the jaws (6, 7) relative to each other in the open position. 7 - Workpiece clamping device according to any one of claims 3 to 6, characterized in that the workpiece head (5) is pushed axially away from the sleeve (1) by elastic means ( 16), and remains in axial abutment against the axially fixed stop (3). 8 - Workpiece clamping device according to any one of claims 3 to 7, characterized in that the longitudinal clamping edges (6b, 7b) are flat and oblique, and in that the pusher (8) comprises corresponding oblique wedge clamping faces (8f, 8g). 15 9 - Workpiece clamping device (4) according to claim 8, characterized in that, in the clamping position, the clamping faces (8f, 8g) of the pusher (8) bear against their entire surface against the longitudinal tightening edges (6b, 7b) of the jaws (6, 7). 10 - Workpiece clamping device according to any one of claims 1 to 9, characterized in that it further comprises means for supplying fluid under pressure (9a, 8i, 14, 15) to bring a fluid under pressure from the spindle of the turning or milling machine or the machine-transfer frame and to project this fluid onto the surfaces (6a, 7a, 5f) for receiving and clamping the workpiece (4) on the workhead (5). 25