Collet actuator for tool holder

[0002] This application claims priority under U.S.C. § 119 (e) to U.S. Provisional application Ser. No. 60/096,428, filed Aug. 13, 1998, which is expressly incorporated by reference herein.

[0003] The present invention relates to a tool holder, and particularly to a tool holder for a high-precision machining center. More particularly, the present invention relates to a collet actuator for use in a tool holder.

[0004] Tool holders are typically used to mount machine tools such are drills, reamers, or grinders to a drill press, machining center, or other machining device. A spindle on the machining device spins the tool holder and the machine tool mounted thereon relative to a workpiece to drill, ream, grid, or otherwise machine the work piece into a desired shape.

[0005] Some tool holder are configured to be removed easily from the machining device to facilitate tool holder replacement and quick change-over between machine tool types or sizes, or to replace worn machine tools. Typically, a machine tool is first gripped by the tool holder and then the tool holder itself is mounted to the machining device.

[0006] According to the present invention, a tool holder includes a body formed to include a collet chamber and a collet-mover chamber, a coilet mounted for movement in the collet chamber, and a collet mover positioned to lie in the collet-mover chamber and coupled to the collet to move the collet relative to the body. The collet includes a tool-gripping surface arranged to define a tool-receiving chamber adapted to receive a machine tool therein.

[0007] The collet moves along a central axis of the body between a tool-grip position to cause the tool-gripping surface to move radially inwardly toward the central axis to grip the machine tool in the tool-receiving chamber and a tool-release position to cause the tool-gripping surface to move radially outwardly away from the central axis to release the machine tool. The collet mover draws the collet along the central axis to the tool-grip position in response to rotation of the collet mover about an axis of rotation in the collet-mover chamber and pushes the collet along the central axis to the tool-release position in response to rotation of the collet mover about an axis of rotation in the collet-mover chamber.

[0008] In preferred embodiments, the body is formed to include a passageway and includes an exterior surface having an edge that defines an access aperture opening into the passageway. The tool holder further includes a driver positioned in the passageway to engage the collet mover to move the collet relative to the body to cause the tool-gripping surface of the collet to engage the machine tool. The access aperture provides access to the driver while the tool holder is mounted on a machining center so that an operator may use a small handle tool, e.g. an alien wrench, to rotate the driver in the passageway and thereby move the collet relative to the body to cause the collet to grip the machine tool while the tool holder remains mounted to the machining center. Therefore, removal of the tool holder from the machining center prior to removal of the machine tool from the tool holder is unnecessary.

[0009] Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.

[0010] The detailed description particularly refers to the accompanying figures in which:

[0011] FIG. 1 is a side elevation view of a tool holder, with portions broken away, gripping a machine tool and showing the tool holder including a conical shank positioned to lie in a spindle (shown in phantom), a body positioned to lie outside of the spindle, a collet positioned to lie in the body to grip the machine tool, a collet actuator positioned to lie in the body to move the collet relative to the body to grip the machine tool, a tool holder-change flange positioned to interconnect the conical shank and the body, and a drive tool positioned to extend into the body at a position “below” the tool holder-change flange to engage and operate the collet actuator to cause the movement of the collet relative to the body to either grip or release the machine tool;

[0012] FIG. 2 is an exploded assembly view of a tool holder in accordance with a first preferred embodiment of the present invention showing the tool holder including a body, a tool holder-change flange coupled to the body, a collet aligned for positioning in the body, a collet actuator including a cylindrical worm gear and a worm, and a T-shaped drive tool positioned to engage and rotate the worm;

[0013] FIG. 3 is a side elevation view of the tool holder of FIG. 2, with portions broken away, showing the worm engaging the worm gear to rotate the worm gear in response to rotation of the drive tool and the worm gear engaging the collet to draw the collet into engagement with the body in response to rotation of the worm gear;

[0014] FIG. 3ais a view similar to a portion of FIG. 3 showing movement of the collet to the right to grip a machine tool received therein in response to rotation of the drive tool, worm, and worm gear;

[0015] FIG. 4 is a transverse sectional view taken along line 4—4 of FIG. 3 showing the worm engaging the worm gear;

[0016] FIG. 5 is an exploded assembly view of a tool holder in accordance with a second preferred embodiment of the present invention showing the tool holder including a body, a tool holder-change flange coupled to the body, a collet aligned for positioning in the body, a collet actuator including a driven bevel gear and a drive bevel gear, and a T-shaped drive tool positioned to engage and rotate the drive bevel gear;

[0017] FIG. 6 is a side elevation view of the tool holder of FIG. 5, with portions broken away, showing the drive bevel gear engaging the driven bevel gear to rotate the drive bevel gear in response to rotation of the drive tool and the driven bevel gear engaging the collet to draw the collet into engagement with the body in response to rotation of the driven bevel gear;

[0018] FIG. 7 is a transverse sectional view taken along line 7—7 of FIG. 6 showing the drive bevel gear engaging the driven bevel gear;

[0019] FIG. 8 is an exploded assembly view of a tool holder in accordance with a third preferred embodiment of the present invention showing the tool holder including a body, a tool holder-change flange coupled to the body, a collet aligned for positioning in the body, and a collet actuator including a pair of wedges and a differential screw;

[0020] FIG. 9ais a side elevation view of the tool holder of FIG. 8, with portions broken away, showing the differential screw engaging the wedges to push the wedges apart in response to rotation of the drive tool and the wedges engaging cam surfaces on the body to draw the collet into engagement with the body in response to separation of the wedges;

[0021] FIG. 9bis a transverse sectional view taken along line 9b—9bof FIG. 9ashowing the differential screw engaging the wedges;

[0022] FIG. 10ais a view similar to FIG. 9ashowing radially outward movement of the wedges to draw the collet further to the right to grip a machine tool received therein;

[0023] FIG. 10bis a transverse sectional view taken along line 10b—10bof FIG. 10ashowing the differential screw moving the wedges radially outward;

[0024] FIG. 11 is an end view of a collet suitable for use in the tool holder shown in FIGS. 2 and 5;

[0025] FIG. 12 is a section of the tool holder taken along line 12—12 of FIG. 11;

[0026] FIG. 13 is an end view of a second embodiment of a collet that is suitable for use in the tool holder of FIGS. 2 and 5;

[0027] FIG. 14 is a sectional view of the tool holder taken along line 14—14 of FIG. 13;

[0028] FIG. 15 is an end view of a third embodiment of a collet that is suitable for use in the tool holder of FIGS. 2 and 5;

[0029] FIG. 16 is a sectional view of the tool holder taken along line 16—16 of FIG. 15;

[0030] FIG. 17 is an end view of a fourth embodiment of a collet that is suitable for use in the tool holder of FIGS. 2 and 5;

[0031] FIG. 18 is a sectional view of the tool holder taken along line 18—18 of FIG. 17;

[0032] FIG. 19 is an end view of a fifth embodiment of a collet that is suitable for use in the tool holder of FIGS. 2 and 5; and

[0033] FIG. 20 is a sectional view of the tool holder taken along line 20—20 of FIG. 19.

[0034] A tool holder 1 according to the present invention is shown in FIG. 1. Tool holder 1 includes a conical shank 2, a tool holder-change flange 3 coupled to conical shank 2, a body 4 coupled to tool holder-change flange 3, a collet 5 positioned to lie in body 4 to grip a machine tool 6, and a collet actuator 7 positioned to lie in body 4 to move collet 5 relative to body 4 to cause collet 5 to grip machine tool 6.

[0035] Collet actuator 7 includes a collet mover 8 coupled to collet 5 and a driver 9 rotated by a drive tool 11. Driver 9 is positioned to engage collet mover 8 so that collet mover 8 draws collet 5 axially inward in response to rotation of drive tool 11 in one direction to grip machine tool 6 and pushes collet 5 axially outward in response to rotation of the drive tool 11 in an opposite direction to release machine tool 6 so that machine tool 6 can be released and replaced without removing tool holder 1 from spindle 13.

[0036] Conical shank 2 is configured to be mount in a spindle 13 (in phantom) of a machining center and tool holder-change flange 3 is configured to be gripped by an automated tool holder changer (not shown) to facilitate the removal of tool holder 1 from spindle 13 and insertion of another tool holder (not shown) into spindle 13 by the tool holder changer. Tool holder 1 may be rigidly or otherwise mounted to other machining devices such as, for example, drills, drill presses, or CNC machines.

[0037] Collet actuator 7 is accessible to an operator while tool holder 1 is mounted on spindle 13 to permit an operator to change machine tool 6 without removing tool holder 1 from spindle 13. Body 4 is formed to include a collet chamber configured to receive collet 5, an actuator chamber 17 including a collet-mover chamber 19 configured to receive collet mover 8, and a passageway 29 configured to receive driver 9. Body 4 further includes an exterior surface 23 including an edge 35 defining an access aperture 27 positioned axially outward of spindle 13 and tool holder-change flange 3. By positioning access aperture 27 outside of spindle 13, an operator may insert drive tool 11 into the interior region of body 4 to engage and operate collet actuator 7 so that collet 5 may be moved relative to body 4 to grip or release machine tool 6 without removing tool holder 1 from spindle 13.

[0038] Referring to FIG. 2, a tool holder 10 includes a collet 20, a depth-adjustment screw 30, a collet mover 40, a driver 50, and a body 60. Collet mover 40 is mounted for rotation in a collet-mover chamber 61 formed in body 60 using a snap ring 70 that fits into an annular channel 62 formed in body 60. Collet 20 includes a body 21 and a threaded post 22 that is configured to mate in threaded engagement with a threaded aperture 41 formed in collet mover 40 when collet 20 is mounted in a collet chamber 63 formed in body 60 as shown, for example, in FIG. 3. Collet 20 is arranged to move relative to body 60 back and forth along central axis 44 in response to rotation of collet mover 40 about axis 44.

[0039] Depth-adjustment screw 30 is mounted for rotation in a threaded aperture 23 formed in post 22 of collet 20 to enable an operator to rotate screw 30 using a screw rotator tool during machine set-up to set the operating depth of a machine tool 6 (shown in FIG. 3a) extending into a tool-receiving chamber 24 formed in collet 20 and retained in tool holder 10. Depth-adjustment screw 30 includes an inner end 31 that lies in tool-receiving chamber 24 and engages a tool (not shown) received therein and an outer end 32 configured to be coupled to the screw rotator tool (not shown). Threads 33 on depth-adjustment screw 30 threadedly engage the threads provided in aperture 23 formed in post 22 of collet 20.

[0040] Collet mover 40 is a worm gear and driver 50 is a worm having a helical drive thread 51 that threadedly engages an exterior gear-teeth thread 42 formed on an outer surface 43 of collet mover 40. Body 60 is formed to include a passageway 64 arranged to communicate with collet-mover chamber 61 so that driver 50 can be rotated about central axis 52 to cause collet mover 40 to rotate in collet-mover chamber 61 about axis of rotation 44.

[0041] Body 60 further includes an exterior surface 75 having a edge 77 defining an access aperture 79 opening into passageway 64. Driver 50 includes an exposed head 53 that is accessible through access aperture 79 into passageway 64 in body 60 so that an operator can engage a drive tool 54 to head 53 and operate the tool (e.g., allen wrench) to rotate driver 50 in passageway 64 about central axis 52. Driver 50 is mounted for rotation in passageway 64 formed in body 60 using a snap ring (not shown) that fits into an annular channel (not shown) formed in body 60 and arranged to communicate with passageway 64 (see snap ring 80 and annular channel 165 for guidance in FIGS. 5-7).

[0042] As shown in FIG. 3a, a shank 91 of machine tool 6 is first inserted into the tool-receiving chamber 24 formed in collet 20 while the tool-gripping surface(s) 25 of collet 20 are “relaxed” and not wedged radially inwardly to grip shank 91 of tool 6. Rotation of driver 50 about central axis 53 in a first direction rotates collet mover 40 about axis of rotation 44 and, due to threaded engagement of threaded post 22 of collet 20 and threaded aperture 41 of collet mover 40, creates a draw on collet 20 so that collet 20 is actuated and moved from left to right relative to body 60 in FIG. 3. As the collet 20 moves to the right, a “wedging action” causes the tool-gripping surface(s) 25 to move radially inwardly to grip shank 91 of tool 6 very tightly so that tool 6 is retained in tool holder 10.

[0043] Rotation of driver 50 about central axis 53 in an opposite second direction causes collet mover 40 to push collet 20 from right to left relative to body 60 in FIG. 3 so as to “release” shank 91 of tool 6 from the tight grip of collet 20 so that machine tool 6 can be removed from tool holder 10. Snap ring 70 retains collet mover 40 in position in collet-mover chamber 61 has a bearing surface 71 that serves as the thrust-bearing base to pull against while collet mover 40 draws collet 20 further into body 60. Body 60 includes an integral bearing wall 81 positioned on the opposite side of collet mover 40 from snap ring 70 that has a bearing surface 73 that servers as thrust-bearing base to support collet mover 40 as collet 20 is pushed axially outward from body 60.

[0044] Referring to FIG. 5, a tool holder 100 includes a collet 20, a depth adjustment screw 30, a collet mover 140, a driver 150, and a body 160. Collet mover 140 is mounted for rotation in a collet-mover chamber 61 formed in body 160 using a snap ring 70 that fits into an annular channel 62 formed in body 160. Collet 20 includes a body 21 and a threaded post 22 that is configured to mate in threaded engagement with a threaded aperture 41 formed in collet mover 140 when collet 20 is mounted in a collet chamber 63 formed in body 160 as shown, for example, in FIG. 6.

[0045] Depth-adjustment screw 30 is mounted for rotation in a threaded aperture 23 formed in collet 20 to enable an operator to rotate screw 30 using a tool (not shown) during machine setup to set the operating depth of a tool (not shown) extending into a tool-receiving chamber 24 formed in collet 20 and retained in tool holder 10. Collet 20 also includes tool-gripping surface(s) 25 in tool-receiving chamber 24.

[0046] Collet mover 140 is a driven bevel gear and driver 150 is a drive bevel gear having a tapered gear-teeth thread 151 that threadedly engages an exterior tapered gear-teeth thread 142 formed on an outer surface 143 of collet mover 140. Body 160 is formed to include a passageway 164 arranged to communicate with collet-mover chamber 161 so that driver 150 can be rotated about central axis 152 to cause collet mover 140 to rotate in collet-mover chamber 161 about axis of rotation 44. Body 160 further includes an exterior surface 175 having a edge 177 defining an access aperture 179 opening into passageway 164. Driver 150 includes an exposed head 153 that is accessible through access aperture 179 into passageway 164 in body 160 so that an operator can engage a drive tool 154 to head 153 and operate the tool (e.g., allen wrench) to rotate driver 150 in passageway 164 about central axis 152. Driver 150 is mounted for rotation in passageway 164 formed in body 160 using a snap ring 80 that fits into an annular channel 165 formed in body 160.

[0047] Shank 91 of tool 6 shown in FIG. 3acan be gripped by collet 20 in the manner shown in FIG. 3aby using drive tool 154 to rotate driver 150 which, in turn, rotates collet mover 140. Rotation of driver 150 about central axis 153 in a first direction rotates collet mover 140 about axis of rotation 44 and, due to threaded engagement of threaded post 22 of collet 20 and threaded aperture 141 of collet mover 140, creates a draw on collet 20 so that collet 20 is actuated and moved from left to right relative to body 160 in FIG. 6. Rotation of driver 150 about central axis 153 in an opposite second direction causes collet 20 to move from right to left relative to body 160 in FIG. 6 so as to release shank 91 of tool 6 from the tight grasp of collet 20.

[0048] Snap ring 70 retains collet mover 140 in position in collet-mover chamber 161 and serves as the thrust-bearing base to pull against while collet mover 140 draws collet 20 further into body 160. Body 160 includes an integral bearing wall 181 positioned on the opposite side of collet mover 140 from snap ring 70 that has a thrust surface 183 that servers as thrust-bearing base to support collet mover 140 as collet 20 is pushed axially outward from body 160.

[0049] Referring to FIG. 8, a tool holder 200 includes a collet 220, a collet mover 240 including first and second wedges 241, 242, a driver 250, and a body 260. Collet 220 includes a body 221, a base 222, and a shank 223 coupled to body 221 and base 222 and arranged to define first and second wedge-receiving spaces 224, 225 therebetween. Shank 223 is formed to include an aperture 226 for receiving driver 250 therein and allowing rotation of driver 250 about an axis of rotation 251. Collet 20 further includes a tool-receiving chamber 234 and tool-gripping surface(s) 235 in tool-receiving chamber 234. Compression springs 236 (see FIG. 8) are arranged to act against base 222 and against body 260 as shown, for example, in FIG. 9a.

[0050] Collet base 222 is sized to fit into a base chamber 266 formed in body 260 as shown in FIGS. 8 and 9aand collet body 221 is sized to fit into a collet chamber 267 formed in body 260. Collet shank 223 passes through a wedge-receiving chamber 261 formed in body 260 to expose the openings into aperture 226 to open regions of wedge-receiving chamber 261.

[0051] Wedges 241, 242 cooperate to define collet mover 240 and are mounted for reciprocating movement in a wedge-receiving chamber 261 formed in body 260. Wedge 241 includes an aperture 243 having a right-hand thread 244 and wedge 242 includes an aperture 245 having a left-hand thread 246 therein. Wedge 241 includes a first cam follower 246 engaging a first drive cam 262 formed on body 260 and arranged to face into wedge-receiving chamber 261 and a second cam follower 247 engaging a first release cam 263 formed on body 260 and arranged to face into wedge-receiving chamber 261. Wedge 242 includes a first cam follower 248 engaging a second drive cam 264 formed on body 260 and arranged to face into wedge-receiving chamber 261 and a second cam follower 249 engaging a second release cam 265 formed on body 260 and arranged to face into wedge-receiving chamber 261.

[0052] Driver 250 is a differential screw having a right-hand thread 253 on one end 252 and a left-hand thread 254 on an opposite end 255. When driver 250 is rotated about axis 251 in one direction, it causes equal spreading of wedges 241, 242 apart and when driver 250 is rotated about axis 251 in the opposite direction it brings wedges 241, 242 closer together equally.

[0053] Body 260 further includes an exterior surface 275 having a edge 277 defining an access aperture 279 opening into passageway 264. Driver 250 includes an exposed head 256 that is accessible through access aperture 279 into a passageway 264 formed in body 260 so that an operator can engage a tool (not shown) to head 256 and operate the tool (e.g., allen wrench) to rotate driver in passageway 264 about central axis 251. Passageway 264 includes one reach 268 having an outer opening formed in an exterior surface of body 260 and an inner opening communicating with wedge-receiving chamber 261 and another reach 269 having an outer opening formed in an exterior surface of body 260 and an inner opening communicating with wedge-receiving chamber 261 as shown, for example, in FIG. 8.

[0054] Collet 220 is positioned initially in a tool-releasing position as shown in FIG. 9ato enable an operator to insert the shank of a tool easily into tool-receiving chamber 234 of collet 220. Wedges 241, 242 of collet mover 240 are positioned by driver 250 to lie in close but spaced-apart relation from one another in radially inward positions as shown, for example, in FIG. 9b.

[0055] Shank 91 of tool 6 is gripped by collet 220 as shown in FIG. 10aby rotating driver 250 about axis 251 in a first direction to move wedges 241, 242 away from one another in wedge-receiving chamber 261 to create a draw on collet 220 so that collet 220 is actuated and moved from left to right relative to body 260 as shown in FIG. 10a. First cam follower 246 on wedge 241 rides on first drive cam 262 on body 260 and first cam follower 248 on wedge 242 rides on second drive cam 264 on body 260 to cause collet 220 to move to the right. As the collet 220 moves to the right, a wedging action causes the tool-gripping surface(s) 235 to move radially inwardly to grip shank 91 of tool 6 very tightly.

[0056] Shank 91 of tool 6 is released by collet 220 by rotating driver 250 about axis 251 in an opposite, second direction to move wedges 241, 242 toward one another in wedge-receiving chamber 261. Second cam follower 247 on wedge 241 rides on first release cam 263 on body 260 and second cam follower 249 on wedge 242 rides on second release cam 265 on body 260 to cause collet 220 to move relative to body 260 back to the left to reach its initial position shown in FIG. 8. As the collet 220 moves to the left, a releasing action causes the tool-gripping surface(s) 235 to move radially outwardly to release shank 91 of tool 6.

[0057] Five collets suitable for use in a tool holder such as the ones shown in FIGS. 2 and 5 are illustrated in FIGS. 11-20. The collet shown in FIGS. 11 and 12 has no splits in it and is configured to “collapse” slightly in a controlled manner to grip a tool received therein in response to compressive forces generated by collet mover 40 and driver 50 or collet mover 140 and driver 150. The collet shown in FIGS. 13 and 14 has a single split therein as shown best in FIG. 13. The collet shown in FIGS. 15 and 16 has multiple splits therein. The collet shown in FIGS. 17 and 18 includes two split lines 308 that go all the way to the depth of the I.D. bore, clean through all the segments and a scalloped relief 309 to allow the segment 310 to wrap around a tool received in the collet without interference. The collet shown in FIGS. 19 and 20 is the same as the collet shown in FIGS. 17 and 18 except there is no split that extends to the I.D. bore. The body of these collets are capable of being used in tool holder 200 by coupling said bodies to shank 223 of collet 220.

[0058] Although the invention has been disclosed in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of the invention as recited in the following claims.