JP5376161B2 - Collet chuck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a collet chuck capable of highly accurately processing by restraining deformation of a workpiece by grasping by uniform grasping force, even in the thin annular ring-shaped workpiece nonuniform in an inner peripheral surface. <P>SOLUTION: A draw bar is constituted of a first draw bar 3a sliding in a through-hole 7 arranged in a chuck body 2 and a second draw bar 3b sliding in a through-hole 13 arranged in the first draw bar 3a, and respective sliding contact parts A and B between tapered surfaces 15a and 15b of the respective draw bars and a tapered surface 25 of a collet 4 and a workpiece gripping part 24 are respectively dividedly limited to a local range of the circumference. While setting a clearance Sa between a sliding shaft part 12a of the first draw bar 3a and the through-hole 7 as a minimum clearance capable of sliding the first draw bar 3a, a clearance Sb between a sliding shaft part 12b of the second draw bar 3b and the through-hole 13 is set as a clearance larger than a nonuniform quantity of a workpiece inner peripheral surface, and the respective draw bars 3a and 3b are respectively independently operated. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a collet chuck including a collet divided into a plurality of segments, and more particularly to an inner diameter collet chuck that grasps an inner peripheral surface (inner diameter) of an annular workpiece.

  Conventionally, when a chuck device attached to a lathe or the like is used to grasp and process the inner peripheral surface of a thin annular workpiece with a small wall thickness, a collet chuck with less deformation of the workpiece due to grasping force than a three-claw chuck has been used. Is called. In this collet chuck, a chuck body attached to a spindle end of a lathe is provided with a collet that grips a workpiece and a draw bar that is in sliding contact with the collet. The draw bar includes a tapered portion having a tapered surface on the outer peripheral surface. The collet grips a workpiece on the outer peripheral surface, has a tapered surface on the inner peripheral surface, and is divided into a plurality of segments by slits.

  In the collet chuck, when the draw bar slides back and forth in the axial direction in the through hole of the chuck body, the tapered surface of the tapered portion of the draw bar comes into sliding contact with the tapered surface of each segment of the collet, and each segment has a radius. The diameter of the collet is increased in the direction, and the grip portion of the outer peripheral surface of each segment of the collet comes into contact with the inner peripheral surface of the work to grip the work.

  As such a collet chuck, Patent Document 1 discloses an inner diameter collet chuck. This inner diameter collet chuck can suppress the deformation of the workpiece that lowers the machining accuracy, especially when machining an extremely thin annular workpiece, and can hold the workpiece while ensuring the roundness of the inner diameter. The surface can be processed with high accuracy.

JP-A-8-19909

  The inner diameter collet chuck of Patent Document 1 is effective for a work having a uniform inner peripheral surface, for example, a work surface having a good roundness, but is not uniform on the inner peripheral surface. It is impossible to grasp a workpiece having an elliptical inner diameter such as a forged product or a cast product with a uniform grasping force. Therefore, if the inner peripheral surface is a non-uniform workpiece, and a thin annular workpiece is grasped, the workpiece may be deformed and machining accuracy may be deteriorated.

  The present invention solves the above-mentioned problems in the prior art. Even a thin annular workpiece with a non-uniform inner peripheral surface can be grasped with a uniform grasping force to suppress workpiece deformation and processed with high accuracy. An object of the present invention is to provide a collet chuck that can be used.

  In order to solve the above problems, the present invention provides a chuck body with a collet that grips a workpiece and a draw bar that is in sliding contact with the collet. The draw bar has a tapered surface on the outer peripheral surface, and slides in the through hole in the axial direction. The collet grips the inner peripheral surface of the workpiece on the outer peripheral surface, and a tapered surface is formed on the inner peripheral surface and is divided into a plurality of segments by slits. The tapered surface of the draw bar is compared with the tapered surface of the collet. In a collet chuck in which the collet expands by sliding and the workpiece gripping part abuts on the workpiece and grips the workpiece, the draw bar is composed of a plurality of draw bars, and each draw bar slides between the tapered surface and the inside of the through hole. Each having a sliding shaft portion that moves, and each sliding contact portion between the tapered surface of each draw bar and the tapered surface of the collet, and the workpiece gripping portion, respectively. In addition to being divided into the local ranges of the above, a predetermined gap different between the sliding shaft portion of each draw bar and the through-hole in which they slide is provided, and each draw bar is operated independently. And

  The draw bar includes a first draw bar that slides in a through hole provided in the chuck body and a second draw bar that slides in a through hole provided in the first draw bar, and the first draw bar slides. The clearance between the shaft portion and the through hole provided in the chuck body is set to a minimum clearance that allows the first draw bar to slide, while the sliding shaft portion of the second draw bar and the first draw bar are provided. The gap between the through holes is larger than the non-uniform amount of the work inner peripheral surface.

  In addition, the tapered surfaces of the two draw bars and the sliding contact portions of the tapered surface of the collet are alternately arranged at circumferentially equal positions on the inner peripheral surface of the collet, and the workpiece gripping portion on the outer peripheral surface of the collet And the two workpiece gripping portions are arranged symmetrically on the outer peripheral surface of each segment, the sliding contact portion is arranged at the center of each segment, and the workpiece gripping portion is slid. It is characterized in that it is arranged evenly on the left and right with respect to the contact portion.

  According to the collet chuck of the present invention, even a thin annular workpiece having an uneven inner peripheral surface can be grasped with a uniform grasping force, so that deformation of the workpiece can be suppressed and machining can be performed with high accuracy. it can.

It is a collet chuck front view of an embodiment of the present invention. It is II-II sectional drawing of FIG. It is the C section enlarged view of FIG. FIG. 2 is an enlarged view of the center portion of the collet chuck in FIG. 1.

  Hereinafter, a collet chuck according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the left-right direction in FIG. 2 is referred to as “axial direction”, the right side is referred to as “front”, and the left side is referred to as “rear”. The direction orthogonal to the axial direction is referred to as “radial direction”, the chuck shaft center (center line) side is referred to as “inner”, and the opposite side is referred to as “outer”.

  First, the overall configuration of the collet chuck will be described with reference to FIGS. A collet chuck 1 shown in FIGS. 1 and 2 is an inner diameter collet chuck that is attached mainly to a spindle end of a lathe and grasps an inner peripheral surface (inner diameter) of an annular workpiece.

  The collet chuck 1 includes a chuck body 2, a draw bar 3, a collet 4, and a work stopper 5. The collet chuck 1 is attached to the spindle end of a lathe (not shown) via an adapter 6 attached to the rear end face of the chuck body 2. The chuck body 2 is provided with a through hole 7 in which the draw bar 3 is in sliding contact with the shaft center. On the other hand, a flange portion 8 for attaching the adapter 6 is formed on the outer peripheral portion of the chuck body 2, and a fitting shaft portion 9 into which the collet 4 is inserted is formed in front of the flange portion 8.

  The draw bar will be described. As shown in FIG. 2, the draw bar 3 slides in the through hole 7 of the chuck body 2 in the axial direction, and transmits the thrust of a rotating cylinder (not shown) as a drive source to the collet 4. The draw bar 3 is connected to a piston rod (not shown) of the rotary cylinder by a connecting member (not shown) that is screwed into the rear threaded portion 10. The front portion is a tightening taper portion 11 formed with a taper surface 15 slidably contacting the taper surface 25 of the inner peripheral surface of the collet 4, and the rear portion is a slide that slides in the through hole 7 of the chuck body 2. A shaft portion 12 is formed.

  The draw bar 3 of the present invention is composed of a plurality of members, and in the present embodiment, it is composed of two draw bars, a first draw bar 3a and a second draw bar 3b. Each of these draw bars includes a tightening taper portion 11a, a sliding shaft portion 12a (first draw bar 3a), a tightening taper portion 11b, and a sliding shaft portion 12b (second draw bar 3b).

  In the first draw bar 3a, the sliding shaft portion 12a slides in the through hole 7 formed in the chuck body 2, and the through hole 13 through which the second draw bar 3b is inserted is formed in the shaft center. A female thread 14 for connecting to the piston rod of the rotating cylinder is formed at the rear end of the through hole 13. The female screw 14 is processed to have a larger diameter than the inner diameter of the through hole 13. On the other hand, as shown in FIG. 3, a taper surface 15a is formed on the outer peripheral surface of the tightening taper portion 11a so as to be in sliding contact with the taper surface 25 of the inner peripheral surface of the collet 4, and this taper surface 15a expands forward. It is a tapered taper.

  As shown in FIG. 4, the front end surface of the tightening taper portion 11a of the first draw bar 3a is divided up to the vicinity of the front end surface 22 of the chuck body 2 by the radially processed slits 17, and the tapered surface 15a is divided. Yes. In the present embodiment, the tightening taper portion 11a is divided into three equal parts in a fan shape. The three slits 17 are fitted with the tightening taper portions 11b of the second draw bar 3b, which is also divided into three. The through hole 13 in the portion where the slit 17 is formed is a square hole so that the central portion of the tightening taper portion 11b of the second draw bar 3b can be accommodated. Since it is three places, it is formed in a substantially equilateral triangle.

  As shown in FIG. 4, each tapered surface 15 a divided by the slit 17 has a sliding contact portion with the collet 4 not in the entire taper surface but in sliding contact with the collet 4 in a local range. In the present embodiment, the relief portion 16 is formed on the outer periphery, and the local sliding contact portion A with the collet 4 in the first draw bar 3a is the central portion in the circumferential direction of each of the fastening taper portions 11a divided into fan shapes. That is, there are three locations at the center of each tapered surface 15a.

  The second draw bar 3b has a sliding shaft portion 12b that slides in the through hole 13 of the first draw bar 3a at the rear portion, and the male screw 19 formed at the rear end portion of the rotary cylinder is the same as the first draw bar. It is connected to a piston rod (not shown). The tightening taper portion 11b of the second draw bar 3b is also formed with a tapered surface 15b on the outer peripheral surface thereof similarly to the first draw bar 3a, and the taper angle and diameter are the same as those of the first draw bar 3a. The tightening taper portion 11b is radially divided into three with a predetermined thickness in the circumferential direction so as to be fitted into the three slits 17 of the tightening taper portion 11a of the first draw bar 3a, and the tapered surface 15b is divided. Has been.

  Thus, each taper surface 15b of the fastening taper portion 11b that is divided and fitted into the slit 17 becomes a local sliding contact portion B with the collet 4 in the second draw bar 3b. Therefore, the local sliding contact portions A and B in the circumferential direction of the taper surfaces 15 (taper surfaces 15a and 15b) of the integrated draw bar 3 (first draw bar 3a and second draw bar 3b) are shown in FIG. There will be a total of 6 locations with the circumference divided into 6 equal parts.

  As described above, the collet chuck 1 includes the two draw bars 3a and 3b having the tapered surfaces 15a and 15b, respectively. The sliding contact portions A and B between the tapered surfaces and the collet 4 have a plurality of circumferential directions. The part which is divided into the local range and where the load of the draw bar 3 acting on the collet 4 acts is partially limited.

  As shown in FIG. 3, the collet chuck 1 is provided with different predetermined gaps between the sliding shaft portions 12a and 12b of the two draw bars 3a and 3b and the through-holes 7 and 13 with which they slide. . Specifically, a minimum gap Sa in which the first draw bar 3a can slide is provided between the sliding shaft portion 12a of the first draw bar 3a and the through hole 7 of the chuck body 2. On the other hand, a gap Sb larger than the non-uniform amount of the work inner peripheral surface is provided between the sliding shaft portion 12b of the second draw bar 3b and the through hole 13 of the first draw bar 3a.

  The rotating cylinder that drives the two draw bars by thrusting is a double cylinder in which the two cylinders move independently, and has two piston rods (not shown), each of which can be operated independently. Is. In addition, the two draw bars are restricted by the rotation stop bolt 18 and the guide groove provided in the chuck body, and the rotation around the axis is regulated. The guide groove is an elongated hole and the two draw bars slide back and forth. It is possible.

  The collet 4 will be described. An annular collet 4 having a flange portion 20 at the rear portion is fitted on the outer periphery of the fitting shaft portion 9 of the chuck body 2, and the flange portion 20 is fixed to the end surface of the flange portion 8 of the chuck body 2 with a bolt. As shown in FIGS. 3 and 4, the outer peripheral surface of the collet 4 is divided into a plurality of segments 23 by slits 21 from the front end surface 29 to the front portion of the flange portion 20. In the present embodiment, the collet 4 is divided into six by six slits 21.

  The six segments 23 of the collet 4 are formed with a workpiece gripping portion 24 that grips a workpiece on the outer peripheral surface of the front end portion, and a tapered surface 25 that expands forward on one inner peripheral surface. The tapered surface 25 of each segment 23 is attached to the chuck body 2 with the tapered surface 15 (tapered surface 15a, tapered surface 15b) of the draw bar 3 (first draw bar 3a, second draw bar 3b) in contact with the tapered surface 25. ing. In the collet 4, only the flange portion 20 is fitted into the fitting shaft portion 9, and the tip portion is not in contact with the small diameter shaft portion 9, so that each segment 23 receives a bending moment from the tapered surface 15 of the draw bar 3. Furthermore, it is easy to elastically deform outward in the radial direction.

  The workpiece gripping portion 24 of each segment 23 is divided by being provided with a plane portion 26 as shown in FIG. 4 so that the contact with the inner peripheral surface of the workpiece does not come into contact with the entire surface. It comes in contact with and grips. In the present embodiment, the outer peripheral surface of the collet 4 is processed into a polygonal shape by twelve flat surface portions 26 that equally divide the circumference, and the 12 outer peripheral surfaces between the flat surface portions 26 are used as the work gripping portions 24. In this way, the collet chuck 1 has a plurality of workpiece gripping portions 24 of each segment 23 of the collet 4 that abuts on the inner peripheral surface of the workpiece, as in the sliding contact portions A and B between the draw bar 3 and the collet 4. It is divided into local ranges.

  The six slits 21 are inserted at every other center in the plane portion 26, and two workpiece gripping portions 24 are arranged symmetrically in the circumferential direction on the outer peripheral surface of each segment 23. Further, regarding the positional relationship in the circumferential direction of the sliding contact portions A and B between the workpiece gripping portion 24 and the draw bar 3, one sliding contact portion A or B is located at the center of each segment 23. That is, the workpiece gripping portions 24 are provided equally to the sliding contact portions A and B, and six collet sliding contact portions A and B are alternately arranged in the middle of the workpiece gripping portion 24. Since the draw bars 3 (the first draw bar 3a and the second draw bar 3b) are restricted from rotating by the anti-rotation bolts 18, the above positional relationship is maintained even when the draw bar 3 slides.

  An annular work stopper 5 having a flange portion 27 at the rear portion is inserted into the outer peripheral surface of the collet 4, and the flange portion 27 is fixed to the flange portion 20 of the collet 4 with bolts. The front end surface 28 of the work stopper 5 is located behind the front end surface 29 of the collet 4, and the inner peripheral surface of the work W can be gripped by the work gripping portion 24 of the collet 4. The workpiece W is positioned in the axial direction by bringing the rear end face of the work W into contact with the front end face 28. The work stopper 5 also has a function of receiving the axial cutting force applied to the work W in the rearward direction.

  The collet chuck 1 can cope with the width dimension of the workpiece W by changing the position of the front end face 27 of the workpiece stopper 5 back and forth. The work stopper 5 is formed thinly in front of the flange portion 27 and is bent so as not to hinder the movement of the collet 4 when a load is received radially outward from the collet 4. The clearance between the outer peripheral surface of the collet 4 at the rear of the work gripping portion 24 and the inner peripheral surface of the work stopper 5 is prevented from entering cutting oil or chips by a seal member 30 (O-ring in the present embodiment). Further, when the cutting oil or chips enter the collet 4 such as the taper surfaces 15 and 25 or the sliding gaps Sa and Sb of the draw bar 3, the collet front end face 29 is blocked by the chip cover 31 attached to the second draw bar 3b. It is prevented. The chip cover 31 is attached to the second draw bar 3B with a fixing screw 32 so as to be movable in the axial direction, and is urged rearward by a spring 33 so as to be in close contact with the collet front end face 29 at all times.

  Next, the operation of the collet chuck 1 will be described. In the following description, the collet 4 segment that engages with the draw bar at the sliding contact portion A is 23a, the segment that is engaged at the sliding contact portion B is 23b, the workpiece gripping portion 24 of the segment 23a is 24a, and the segment gripping of the segment 23b is performed. The part 24 is distinguished from 24b.

  In the collet chuck 1 configured as described above, an annular workpiece W is attached to the workpiece gripping portions 24a and 24b on the outer periphery of the collet, and only the first draw bar 3a is moved backward by the driving force of a rotating cylinder (double cylinder). Move to. Then, a load (bending moment) for expanding the diameter toward the radially outer side is applied to the collet 4 by the action of the three collet sliding contact portions A. Then, only the three segments 23a with which the three collet sliding portions A are in sliding contact receive a bending moment and elastically deform outward in the radial direction, and grip the workpiece W with the respective workpiece gripping portions 24a.

  Next, like the first draw bar 3a, the second draw bar 3b is moved rearward, and the collet 4 is expanded radially outward at the three sliding contact portions B of the second draw bar 3b. At this time, the thrust of the rotating cylinder is the same as that of the first draw bar 3a. Then, this time, the three segments 23b with which the sliding contact portion B comes into sliding contact receives a bending moment and elastically deforms outward in the radial direction, and grasps the workpiece W with the respective workpiece gripping portions 24b.

  Next, the function and effect of the embodiment of the present invention will be described. In the collet chuck 1 configured as described above, the gap Sa of the first draw bar 3a is set to a minimum amount by which the first draw bar 3a can slide, so that when the first draw bar 3a is operated, Each workpiece gripping part 24a centripetally grips and grips the workpiece W. In the second draw bar 3b, the gap Sb is set to be larger than the non-uniform amount of the work inner peripheral surface. Therefore, when the work inner peripheral surface is non-uniform during the operation of the second draw bar 3b. The segment 23b having the workpiece grasping portion 24b follows the radial direction within the gap Sb to grasp the inner peripheral surface of the workpiece W. That is, there is an effect of grasping the inner peripheral surface of the workpiece W while maintaining the grasping accuracy of the workpiece W centered by the workpiece gripping portion 24a.

  Further, the work grasping part 24 of each segment 23 of the collet 4 is equally divided by the plane part 26 at the circumference, and two work gripping parts 24 are arranged symmetrically on the outer peripheral surface of the segment 23. Since the slidable contact portions A and B are arranged in the center and the work gripping portions 24 are arranged equally to the left and right with respect to the slidable contact portions A and B, the work gripping portions 24a and 24b of the segments 23a and 23b elastically deformed by a bending moment. The effect that 24b grasps | tracks uniformly by the internal peripheral surface of the workpiece | work W arises.

  With these actions, it is possible to accurately grip an annular workpiece having a non-uniform inner peripheral surface, such as poor roundness of the inner peripheral surface of the workpiece, with a uniform grasping force. Therefore, even a thin annular workpiece that is easily distorted can be processed with high accuracy while suppressing deformation due to grasping.

  The present invention is not limited to the above-described embodiment, and can be implemented by appropriately changing a part of the configuration without departing from the gist of the invention. For example, the division of the first draw bar and the second draw bar is not limited to three divisions, and the division number 6 of the collet 4 and the division number 12 of the work gripper 24 can be changed. Further, when the local sliding contact portion A between the first draw bar 3 a and the collet 4 is provided, a relief portion may be provided on the tapered surface 25 side of the collet 4 to divide the tapered surface 25.

DESCRIPTION OF SYMBOLS 1 Collet chuck 2 Chuck main body 3 Draw bar 3a 1st draw bar 3b 2nd draw bar 4 Collet 7 Through hole 12 Sliding shaft part 13 Through hole 15 Tapered surface 21 Slit 23 Segment 24 Work holding part 25 Tapered surface A Sliding contact part B Sliding contact Part Sa Gap Sb Gap

Claims (3)

The chuck body is equipped with a collet that grips the workpiece and a draw bar that slides in contact with the collet. The draw bar has a tapered surface on the outer peripheral surface and slides back and forth in the axial direction inside the through hole. The peripheral surface is gripped, a tapered surface is formed on the inner peripheral surface, and the slit is divided into a plurality of segments. The tapered surface of the draw bar is in sliding contact with the tapered surface of the collet, and the collet expands in diameter. In the collet chuck where the part abuts against the workpiece and grips the workpiece,
The draw bar is composed of a plurality of draw bars, and each draw bar is provided with the tapered surface and a sliding shaft portion that slides in the through-hole, and each slide bar includes a tapered surface and a tapered surface of the collet. The contact portion and the workpiece gripping portion are each divided into a circumferential local range, and a predetermined gap that is different from each other is provided between the slide shaft portion of each draw bar and the through-hole in which they slide. A collet chuck characterized in that each draw bar is applied and operated independently.   The draw bar includes a first draw bar that slides in a through hole provided in the chuck body, and a second draw bar that slides in a through hole provided in the first draw bar, and a sliding shaft portion of the first draw bar And a through hole provided in the first draw bar, and a through hole provided in the first draw bar. 2. The collet chuck according to claim 1, wherein the gap between the holes is a gap larger than a non-uniform amount on the inner peripheral surface of the workpiece.   The tapered surfaces of the two draw bars and the sliding contact portions of the tapered surface of the collet are alternately arranged at circumferentially equal positions on the inner peripheral surface of the collet, and the work gripping portion on the outer peripheral surface of the collet is circular. Dividing equally around the circumference, two workpiece gripping portions are arranged symmetrically on the outer peripheral surface of each segment, the sliding contact portion is arranged at the center of each segment, and the workpiece gripping portion is placed on the sliding contact portion The collet chuck according to claim 1, wherein the collet chuck is arranged evenly on the right and left sides.

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