CLAMPING JAW AND CHUCK

Abstract

A clamping jaw for a chuck includes a jaw body on which there is formed at least one jaw step having a step head, which has a sensor on its end face, for holding a clamping insert which is formed from a base leg and two fastening legs projecting from the base leg. On each of the opposite longitudinal sides of the step head there is formed a threaded bore for receiving a fastening screw whose screw head is received in a through-opening which is formed in the fastening leg of the clamping insert that is assigned to the longitudinal side, wherein, on each side, the longitudinal axes of the threaded bore and of the through-opening assigned thereto have an offset when the base leg bears against the end face. Also, a chuck has a chuck body, in which such clamping jaws are arranged in uniformly-distributed radial jaw guides.

Claims

1. A clamping jaw (4) for a chuck (1), having a jaw body (6) on which at least one jaw step (7) is formed, which step has a step head (9) having a sensor on its end face (22), for holding a clamping insert (10) that is formed from a base leg (11) and two fastening legs (12) that project away from the base leg (11), wherein a threaded bore (32) is formed, in each instance, on the opposite longitudinal sides of the step head (9), to hold a fastening screw (33), the screw head (34) of which is held in a passage opening (35) that is formed in the fastening leg (12) of the clamping insert (10), which leg is assigned to the longitudinal side, and wherein on each side, the longitudinal axes of the threaded bore (32) and of the passage opening (35) assigned to it have an offset when the base leg (11) rests against the end face (22).

2. The clamping jaw (4) according to claim 1, wherein the fastening screws (33) are formed as cylinder screws having a cylindrical screw head (34).

3. The clamping jaw (4) according to claim 1, wherein an undercut (20) having a console radius is formed below the step head (9) on the base of the jaw step.

4. The clamping jaw (4) according to claim 3, wherein a groove (21) is formed on the two sides of the step head (9), in each instance, offset in the direction of the end face (22), relative to the threaded bores (32), which groove runs parallel to the end face (22).

5. The clamping jaw (4) according to claim 1, wherein the end face (22) on the step head (9) runs inclined by a console angle from the outside to the inside, relative to the longitudinal axis.

6. The clamping jaw (4) according to claim 5, wherein the console angle amounts to between 7? and 12?, in particular 10?.

7. The clamping jaw (4) according to claim 5, wherein the side of the base leg (11) of the clamping insert (10) that faces the end face (22) runs at an incline with a clamping insert console angle that is 0.20? to 0.50? smaller than the console angle.

8. The clamping jaw (4) according to claim 1, wherein a clamping insert (36) that requires turning out is made available together with a countersunk screw (38), in which insert the passage opening (35) has a conical surface (39) as a countersunk bore on the outside.

9. The clamping jaw (4) according to claim 8, wherein the longitudinal axis determined by the conical surface (39) and the longitudinal axis of the related threaded bore (32) have a center offset ?x.

10. The clamping jaw (4) according to claim 1, wherein a guide strip (30) that is T-shaped in cross-section is formed on the jaw body (6), in which strip an undercut (20) having a double recess is formed in every throat.

11. A chuck (1) having a chuck body (2), in which clamping jaws (4) according to claim 1 are arranged in radial jaw guides (3) uniformly distributed over the circumference.

Description

[0017] Further advantages, characteristics, and details of the invention are evident from the claims, the following description of preferred embodiments, as well as the drawings. These show:

[0018] FIG. 1 a perspective representation of a chuck having three clamping jaws, with a workpiece clamped in place in an external clamp, with symbolically represented data transmission from one of the clamping jaws,

[0019] FIG. 2 a perspective representation of an isolated clamping jaw, without clamping inserts,

[0020] FIG. 3 a representation of an isolated clamping jaw, corresponding to FIG. 2, having two clamping inserts,

[0021] FIG. 4 a top view of the clamping jaw from FIG. 3,

[0022] FIG. 5 a side view of the clamping jaw from FIG. 3,

[0023] FIG. 6 a perspective view of an isolated clamping insert,

[0024] FIG. 7 a perspective view of an isolate clamping insert in a perspective that deviates from FIG. 6,

[0025] FIG. 8 a front view of the clamping jaw from FIG. 3,

[0026] FIG. 9 the section along the line IX-IX from FIG. 8,

[0027] FIG. 10 the section X-X from FIG. 8,

[0028] FIG. 11 a representation corresponding to FIG. 9, for alignment of the clamping insert,

[0029] FIG. 12 the detail XII from FIG. 11,

[0030] FIG. 13 a representation corresponding to FIG. 3, with an alternative clamping insert at the upper jaw head,

[0031] FIG. 14 a side view of the clamping jaw from FIG. 13,

[0032] FIG. 15 the section XV-XV from FIG. 14,

[0033] FIG. 16 the detail XVI from FIG. 15,

[0034] FIG. 17 a side view of the chuck from FIG. 1,

[0035] FIG. 18 the detail XVIII from FIG. 8, and

[0036] FIG. 19 the detail XIX from FIG. 17.

[0037] In FIG. 1, a chuck 1 is shown that has a chuck body 2, in which clamping jaws 4 are arranged in radial jaw guides 3 distributed uniformly over the circumference. In the exemplary embodiment shown, three radial jaw guides 3 having correspondingly inserted three clamping jaws 4 are shown, wherein, however, a different number of radial jaw guides 3 having assigned clamping jaws 4 is also possible, in particular also a chuck 1 having two clamping jaws 4 or 4, 5, 6 or more than 6 clamping jaws 4. In standard use, the chuck 1 is assigned, in a usual manner, to the working spindle of a machine tool, wherein rotator drive of the chuck 1 takes place by means of the machine tool, as does provision of the activation force to produce the desired clamping force. The radio waves shown symbolically in FIG. 1 indicate the transmission of data to be transmitted wirelessly from the clamping jaws 4 used in the chuck 1 to a reception unit of the machine tool.

[0038] The clamping jaws 4 themselves are shown in detail in FIGS. 2 to 5 and have a jaw body 6, on which at least one jaw step 7 is formed, having a step head 9 for holding a clamping insert 10.

[0039] In the exemplary embodiment shown, two of the jaw steps 7 are shown, wherein here, too, it holds true that a different number is possible, in other words also a clamping jaw 4 having only one jaw step 7, having three jaw steps 7 or having four or five jaw steps 7 can be implemented, depending on the demands of the required clamping conditions. It should be pointed out that the jaw body 6 of the clamping jaw 4 is structured as a step reversal jaw, in other words, in a simple manner, a switch from the outer clamping of the workpiece 31 shown in FIG. 1 to an inner clamping is possible by means of simple reversal of the clamping jaws 4 in the jaw guides 3 of the chuck 1.

[0040] The clamping jaw 4 has a sensor 16 on each jaw step 7, on the end face 22 of the step head 9. Furthermore, the step head 9 is configured for holding the clamping insert 10, which is formed from a base leg 11 and two fastening legs 12 that project away from the base leg 11. On the opposite longitudinal sides of the step head 9, a threaded bore 32 is formed, in each instance, for holding a fastening screw 33, the screw head 34 of which is held in a passage opening 35 that is formed in the fastening leg 12 of the clamping insert 10 that is assigned to the longitudinal side. On each side, the longitudinal axes of the threaded bore 32 and the passage opening 35 assigned to it form an offset when the base leg 11 lies against the end face 22. As FIG. 10, in particular, shows, the fastening screws 33 are formed as cylinder screws having a cylindrical screw head. By means of this structure, it is guaranteed that when a clamping force is in effect, the clamping insert 10 can deform, in such a manner that no clamping force is absorbed by way of the screw head 34, and the sensor 16 can correctly detect the total clamping force that is in effect.

[0041] Below the step head 9, an undercut 20 is formed at the base of the jaw step 7, having a console radius, wherein a groove 21 is formed on the two sides of the step head 9, in each instance, offset relative to the threaded bores 32 in the direction of the end face 22, which groove runs parallel to the end face 22, so that a defined region is delimited for the introduction of force.

[0042] The end face 22 on the step head 9 runs, from the outside to the inside, inclined relative to the longitudinal axis by a console angle, wherein in the exemplary embodiment shown in FIGS. 11 and 12, the console angle amounts to 10?. It should be noted, in this regard, that the side of the base leg 11 of the clamping insert that faces the end face 22 runs at an incline at a clamping insert console angle that is 0.20? to 0.50? smaller than the console angle. In the exemplary embodiment, a clamping insert console angle of 9.75? is shown, which thereby is smaller than the console angle by a lead angle ?? of 0.25?.

[0043] FIGS. 13 to 16 show the case that a clamping insert 36 that requires turning out must be used for clamping a workpiece 31 having an individual clamping diameter. The contour to be achieved by turning it out is shown with a broken line in FIG. 13. This clamping insert 36 that requires turning out is relatively soft, in any case softer than the conventional clamping insert 10 that is shown in FIG. 13 with a fluted gear mechanism 37. For the purpose of turning it out, the clamping insert 36 that requires turning out is made available together with a countersunk screw 38, in which the passage opening 35 has a conical surface 39 on the outside, as a countersunk bore, wherein the longitudinal axis determined by the conical surface 39 and the longitudinal axis of the related threaded bore 32 has a center offset ?x (FIG. 16). For the purpose of turning it out, the countersunk screw 38 is used, so as to guarantee an unambiguous fixation of the position of the clamping insert 36 that requires turning out, wherein after it is turned out, the countersunk screw 38 is replaced with the fastening screw 33 having the cylindrical screw head 34, as shown in FIG. 15 on the side that lies on the bottom.

[0044] FIGS. 18 and 19 indicated that a guide strip 30 that is T-shaped in cross-section is formed on the jaw body 6, on which strip an undercut 40 having a double recess 41 is formed in every throat, and this allows a clear increase in the size of the radius, to reduce the notch stress, as compared with the conventional embodiment shown with broken lines in FIG. 19.

[0045] In general, it holds true that a sensor location 15 is formed on the end face 22 for placement of the sensor 16. In this regard, the sensor location 15 is formed by a pocket 17 in which the sensor 16 is arranged. The sensor 16 itself is formed as a strain gauge 18, in particular as a metal strain gauge, which is welded on in the pocket 17, wherein the contacting surfaces are arranged by way of a passage 19, which is made available for passing through a data line and/or an energy supply line 24 (FIG. 9).

[0046] The clamping inserts 10 themselves have a shape that is U-shaped in cross-section, wherein a counter-pocket 23 is formed on the inner side of the base leg 11, in the center between the fastening legs 12, the dimensions of which counter-pocket is coordinated with those of the pocket 17.

[0047] If clamping in place of a workpiece now takes place, as is evident from FIG. 1, then this is bent in a defined manner by means of the recess formed by the counter-pocket 23 in the clamping insert 10 and by means of the pocket 17 in the end face, in the manner of a bending beam, namely stretched, and this also has an effect on the strain gauge 18, and this brings about a change in resistance or tension that is proportional to the clamping force that is in effect. In this regard, the undercut 20 below the step head 9 brings about a non-disrupted, homogeneous flow of force.

[0048] It should furthermore be noted that for protecting the sensor 16, the pocket 17 that holds the sensor 10 is closed off by means of a cover, which can preferably be removed only in a destructive manner. Finally, it is also evident that a first holder 26 for an electronics housing 27 is provided in the jaw body 6, which holder is connected with the pocket 17 by way of the passage 19, and that a second holder 28 for an energy storage unit 29, in particular a rechargeable battery or a capacitor, is provided in the jaw body 6, which holder is also connected with the passage 19 of the pocket 17. The data recorded by the metal strain gauge 18 can thereby be passed along to the electronics housing 27, in which the required electronics components for data collection and evaluation are accommodated, wherein the raw data or processed data of the sensor 16 are made available to the machine tool in a contact-free manner, by way of a receiver unit.

REFERENCE SYMBOL LIST

[0049] 1 chuck [0050] 2 chuck body [0051] 3 jaw guide [0052] 4 clamping jaw [0053] 5 radio waves [0054] 6 jaw body [0055] 7 jaw step [0056] 9 step head [0057] 10 clamping insert [0058] 11 base leg [0059] 12 fastening leg [0060] 15 sensor location [0061] 16 sensor [0062] 17 pocket [0063] 18 strain gauge [0064] 19 passage [0065] 20 undercut [0066] 21 groove [0067] 22 end face [0068] 23 counter-pocket [0069] 24 data line/energy supply line [0070] 26 first holder [0071] 27 electronics housing [0072] 28 second holder [0073] 29 energy storage unit [0074] 30 guide strip [0075] 31 workpiece [0076] 32 threaded bore [0077] 33 fastening screw [0078] 34 screw head [0079] 35 passage opening [0080] 36 clamping insert that must be turned out [0081] 37 fluted gear mechanism [0082] 38 countersunk screw [0083] 39 conical surface [0084] ?? lead angle [0085] ?x center offset