Collet holding structure for machine tools

Abstract

To provide a collet holding structure for a machine tool that can be easily applied to machine tools equipped with conventional collet holding structures. [Solution] A collet holding structure for a machine tool comprising a spindle 4 rotatably supported on the machine tool body, a flange member 6 attached to the spindle, a collet member 8 mounted on the flange member 6, and a retraction member 10 for retracting the collet member 8 to the rear. In the first usage configuration, the flange member 6 is attached to the spindle 4, and the collet member 8 is attached to the retraction member 10. In the second usage configuration, a spacer member 11 is attached between the spindle 4 and the flange member 6, and a connecting mechanism 12 is attached between the retraction member 10 and the collet member 8, and a petal-shaped connecting mechanism can be used as the connecting mechanism 12.

Description

[Technical Field]

[0001] The present invention relates to a collet holding structure for a machine tool, wherein the collet member is mounted on the main shaft of the machine tool by engaging a tapered portion on the collet member side with a tapered portion on the main shaft side of the machine tool. [Background Art]

[0002] For example, as a collet holding structure for holding a workpiece or the like, a structure using a collet member has been put into practical use (see, for example, Patent Document 1). As a machine tool using such a collet holding structure, one having the structure shown in FIG. 5 is known, for example. Referring to FIG. 5, a conventional collet holding structure includes a flange member 102 attached to a main shaft (not shown) on a machine tool body side, a collet member 104 attached to the flange member 102, and a retracting member 106 attached to the collet member 104. An insertion hole 108 is provided in a central portion of the flange member 102, and the collet member 104 is inserted into the insertion hole 108. A plurality of through holes (not shown) are provided around the insertion hole 108 in the flange member 102, and the flange member 102 is attached to the main shaft by screwing fixing bolts 110 to a front end face (not shown) of the main shaft through these through holes.

[0003] An annular boss portion 112 is provided at a distal end portion of the flange member 102, and the insertion hole 108 extends from the annular boss portion 112 to a rear end of the flange member 102. An enlarged diameter tapered portion is provided at a distal end portion of the insertion hole 108 of the flange member 102 (that is, an inner peripheral surface of the annular boss portion 112), and an enlarged diameter tapered portion is provided at a distal end portion of the collet member 104.

[0004] Furthermore, a female threaded portion 118 is provided at the tip of the retractable member 106, and a male threaded portion 120 is provided at the rear end of the collet member 104. The collet member 104 is attached to the tip side of the retractable member 106 by screwing the female threaded portion 118 and the male threaded portion 120 together. In addition, a mounting through hole 122 is provided in the flange member 102, and a rotation-preventing member 124 is attached to this mounting through hole 122. When attached in this manner, the pin portion 126 at the tip of the rotation-preventing member 124 engages with a pin groove recess 128 provided on the outer circumferential surface of the collet member 104 so as to be able to slide in the axial direction, thereby preventing the relative rotation of the collet member 104 with respect to the flange member 102.

[0005] Furthermore, in relation to the retractable member 106, for example, a fluid cylinder mechanism (not shown) is provided. When this fluid cylinder mechanism extends, the collet member 104 moves via the retractable member 106 towards the tip indicated by arrow 114, opening the collet member 104. This allows, for example, the workpiece to be removed from the collet member 104. When the fluid cylinder mechanism retracts, the collet member 104 moves via the retractable member 106 in the direction indicated by arrow 116, opening the collet member 104 into a gripping state. This allows, for example, the workpiece to be held in the collet member 104. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Publication number 1-44250 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, such a collet holding structure has the following problems. Specifically, when attempting to remove the collet member 104 from the flange member 102 for maintenance, the rotation-preventing member 124 is removed from the flange member 102, and then the collet member 104 is rotated in the loosening direction to release the screw-in state between the female threaded portion 118 on the retraction member 106 side and the male threaded portion 120 on the collet member 104 side. Also, when attempting to attach the collet member 104 (or another collet member 104) to the flange member 102 after maintenance, the male threaded portion 120 of the collet member 104 is screwed into the female threaded portion 118 on the retraction member 106 side through the insertion hole 108 of the flange member 102 and tightened in the tightening direction, and then the rotation-preventing member 124 is attached to the mounting through hole 122 of the collet member 104 and its pin portion 126 is engaged with the pin groove 128 of the collet member 104. Therefore, the process of removing the collet member 104 from the flange member 102 and attaching the collet member 104 to the flange member 102 becomes complicated and cannot be completed in a short amount of time.

[0008] The object of the present invention is to provide a collet holding structure for a machine tool that can be easily applied to machine tools equipped with conventional collet holding structures, and that allows for easy and quick replacement of collet members. [Means for solving the problem]

[0009] The collet holding structure for a machine tool of the present invention comprises a spindle rotatably supported by the machine tool body, a flange member attached to the tip of the spindle, a collet member fitted into an insertion hole of the flange member, and a retraction member for retracting the collet member to the rear, A spacer member is configured to be attachable between the main shaft and the flange member, and a connecting mechanism is configured to be attachable between the retraction member and the collet member, and the axial lengths of the main shaft in the spacer member and the connecting mechanism correspond to each other. In the first mode of use, the flange member is attached to the main shaft and the collet member is attached to the retractable member; and in the second mode of use, the flange member is attached to the main shaft via the spacer member and the collet member is attached to the retractable member via the connecting mechanism.

[0010] In such a collet holding structure for a machine tool, it is preferable to provide a first female screw hole on the tip surface of the spindle, a first through hole in the flange member, a second through hole in the spacer member corresponding to the first screw hole of the spindle, and a second female screw hole in the flange member corresponding to the first through hole. With this configuration, in the second usage form, the second fixing screw is screwed into the first female screw hole of the spindle through the second through hole of the spacer member, and the first fixing screw is screwed into the second female screw hole of the spacer member through the first through hole of the flange member, thereby allowing the spacer member to be easily attached between the spindle and the flange member.

[0011] Furthermore, it is preferable to provide a first female threaded portion at the tip of the retractable member, a first male threaded portion at the rear end of the collet member, a second male threaded portion at the rear end of the first connecting member of the connecting mechanism, and a second female threaded hole at the tip of the second connecting member. With this configuration, in the second usage form, the second male threaded portion of the first connecting member is screwed into the first female threaded portion of the retractable member, and the second female threaded portion of the second connecting member is screwed into the first male threaded portion of the collet member. In this way, the connecting mechanism can be easily attached between the retractable member and the collet member.

[0012] Furthermore, it is preferable to provide a first mounting through-hole in the flange member and a second mounting through-hole in the spacer member, and in the second usage configuration, to attach a first rotation-blocking member to the first mounting through-hole and a second rotation-blocking member to the second mounting through-hole. With this configuration, the first rotation-blocking member can prevent the relative rotation of the collet member with respect to the flange member, and the second rotation-blocking member can prevent the relative rotation of the first connecting member with respect to the spacer member.

[0013] Furthermore, the connecting mechanism can be constructed from a petal-shaped connecting mechanism, with the first petal-connecting member used as the first connecting member and the second petal-connecting member used as the second connecting member. [Effects of the Invention]

[0014] According to the collet holding structure for a machine tool described in claim 1 of the present invention, a spacer member is configured to be attachable between the spindle and flange member on the machine tool body side, and a connecting mechanism is configured to be attachable between the retraction member and the collet member. Since the axial lengths of the spindle in the spacer member and the connecting mechanism correspond, in the first usage configuration in which the flange member is attached to the spindle, it can be used as a collet chuck structure in a normal usage configuration. In the second usage configuration in which the flange member is attached to the spindle via the connecting mechanism and the collet member is attached to the retraction member via the connecting mechanism, it can be used as a collet chuck structure in which the chuck member can be easily replaced. This second usage configuration can be easily applied to existing machine tools, and it is possible to structurally convert existing machine tools to one in which the chuck member can be easily replaced. [Brief explanation of the drawing]

[0015] [Figure 1] An exploded perspective view showing a part of a second usage mode in one embodiment of a tool holding structure for a machine tool according to the present invention. [Figure 2] A cross-sectional view from an oblique angle showing the tool holding structure of Figure 1 in the second usage configuration. [Figure 3]Figure 3(a) is a simplified diagram showing the connecting mechanism of the tool holding structure in the unconnected state, and Figure 3(b) is a simplified diagram showing this connecting mechanism in the connected state. [Figure 4] Figure 1 is an exploded perspective view showing a portion of the tool holding structure in its first usage configuration. [Figure 5] A cross-sectional view of the collet holding structure of a conventional machine tool, seen from an oblique angle. [Modes for carrying out the invention]

[0016] Hereinafter, an embodiment of a collet holding structure for a machine tool according to the present invention will be described with reference to the attached drawings. In Figures 1 and 2, the illustrated collet holding structure 2 comprises a flange member 6 attached to the spindle 4 (see Figure 2) of a machine tool (for example, an NC lathe), a collet member 8 mounted on the flange member 6, and a retraction member 10 for retracting the collet member 8. The spindle 4 is rotatably supported on the spindle portion (not shown) of the machine tool body. As will be described later, in the first mode of use (see Figure 4), the flange member 6 is attached to the tip of the spindle 4 and the collet member 8 is attached to the tip of the retraction member 10. In the second mode of use (see Figures 1 and 2), the flange member 6 is attached to the tip of the spindle 4 via a spacer member 11 and the collet member 8 is attached to the tip of the retraction member 10 via a connecting mechanism 12.

[0017] The main shaft 4 is composed of a hollow shaft-shaped member, with a central through-hole 14 in its center, and multiple (for example, six) first female screw holes 16 are provided on its tip surface at circumferential intervals. The illustrated flange member 6 comprises a cylindrical flange body 18, and an annular flange portion 20 projecting forward (to the lower right in Figure 2) is provided on the tip surface of this flange body 18. This flange member 6 is provided with an insertion hole 22 extending in the front-rear direction (in other words, in the axial direction of the main shaft 4, from the upper left to the lower right in Figures 1 and 2), and this insertion hole 22 extends in the axial direction from one end (front end) to the other end (rear end) of the flange member 6 (flange body 18 and annular flange portion 20).

[0018] The flange member 6 is provided with a plurality of (for example, six) first through holes 24 spaced apart in the circumferential direction, corresponding to the first female screw holes 16 on the spindle 4 side. First fixing screws 26 are used to attach the flange member 6. For example, when attaching the flange member 6 to the spindle 4, the first fixing screws 26 pass through the first through holes 24 of the flange member 6 and are screwed into the first female screw holes 16 of the spindle 4. The state where the flange member 6 is directly attached to the tip end portion of the spindle 4 in this manner constitutes a first usage mode (see FIG. 4). This first usage mode has a structure that is substantially the same as a conventional collet holding structure; refer also to FIG. 5 for the specific structure thereof.

[0019] The illustrated collet member 8 includes a hollow cylindrical collet body 28, and a plurality of (for example, three as shown in FIG. 1) slits 30 are provided spaced apart in the circumferential direction on the tip end side of the collet body, and these slits 30 extend from the tip end to near the center in the axial direction. A first male screw portion 32 is provided at the rear end portion of the collet body 28.

[0020] The tip end portion of the collet member 8 is provided with a diameter-expanding tapered portion 34 that increases in diameter toward the front in the axial direction, and corresponding to this diameter-expanding tapered portion 34, a diameter-expanding tapered portion 36 that increases in diameter toward the front in the axial direction is provided on the inner peripheral portion of the insertion hole 22 at the tip end portion of the flange member 6. With this configuration, when the collet member 8 is moved in the direction indicated by arrow 38 in a manner described later, the diameter-expanding tapered portion 34 on the collet member 8 side is pressed against the diameter-expanding tapered portion 36 on the flange member 6 side, the collet member 8 is elastically deformed in the radial direction to enter a gripping state where it grips a workpiece, and when the collet member 8 is moved in the direction indicated by arrow 40 in a manner described later, the diameter-expanding tapered portion 34 on the collet member 8 side separates from the diameter-expanding tapered portion 36 on the flange member 6 side, and the collet member 8 returns to its original state to enter an open state (grip-released state) where it releases the grip of the workpiece.

[0021] A first female threaded portion 44 is provided at the distal end of the retracting member 10 so as to correspond to a first male threaded portion 32 of the collet member 8, the first male threaded portion 32 of the collet member 8 is screwed onto the first female threaded portion 44, and the state in which the collet member 8 is directly attached to the retracting member 10 in this manner constitutes a first mode of use (see Fig. 4). Although not illustrated in the drawing, a cylinder mechanism (for example, a pneumatic cylinder mechanism) for retracting the retracting member 10 rearward (in the direction indicated by arrow 38) is provided on the rear end side of the retracting member 10.

[0022] With this configuration, in the first mode of use, when the output portion of the cylinder mechanism is extended, for example, the collet member 8 moves in the direction indicated by arrow 40 via the retracting member 10 to enter a grip release state (open state), and when the output portion is contracted, for example, the collet member 8 moves in the direction indicated by arrow 38 via the retracting member 10 to enter a gripping state.

[0023] In this collet holding structure 2, as shown in Fig. 1 and Fig. 2, a coupling mechanism 12 is configured to be attachable between the retracting member 10 and the collet member 8. To further describe, the illustrated coupling mechanism 12 is formed of a petal coupling mechanism known per se, and includes a first petal coupling member 52 and a second petal coupling member 54 that are detachably coupled to each other. In this embodiment, the first petal coupling member 52 is in the shape of a hollow sleeve, an annular inner flange 56 protruding radially inward is provided at one end (distal end) thereof, and a plurality of (six in this embodiment) petal-shaped recesses 58 are provided on the inner peripheral portion of the annular inner flange 56 at intervals in the circumferential direction. A second male threaded portion 60 is provided at the other end (rear end) of the first petal coupling member 52 so as to correspond to the first female threaded portion 44 of the retracting member 10, and by screwing the second male threaded portion 60 onto the first female threaded portion 44, the first petal coupling member 52 of the coupling mechanism 12 can be attached to the distal end of the retracting member 10.

[0024] Furthermore, the second petal connecting member 54 is hollow sleeve-shaped, and one end (tip) of it is provided with a second female threaded portion 62 corresponding to the first male threaded portion 32 of the collet member 8. By screwing the second female threaded portion 62 onto the first male threaded portion 32, the second petal connecting member 54 can be attached to the rear end of the collet member 8. The other end of the second petal connecting member 54 is provided with an annular outer flange 64 that protrudes radially outward, and a plurality of petal-shaped projections 66 (six in this embodiment) are provided on the outer circumference of this annular outer flange 64 at intervals in the circumferential direction.

[0025] In the second mode of use, in which a connecting mechanism 12 is installed between the retraction member 10 and the collet member 8, a spacer member 11 is installed between the spindle 4 and the flange member 6. The length of this spacer member 11 (i.e., the axial length of the spindle 4) corresponds to the length of the connecting mechanism 12 (i.e., the axial length of the spindle). By configuring it in this way, the positional relationship between the spindle 4 and the flange member 6 and the retraction member 10 and the collet 8 in the first mode of use (in other words, the mode of use without the spacer member 11 and the connecting mechanism 12) can be kept the same as the positional relationship between the spindle 4 and the flange member 6 and the retraction member 10 and the collet 8 in the second mode of use (in other words, the mode of use with the spacer member 11 and the connecting mechanism 12).

[0026] The spacer member 11 is provided with a second through-hole 68 corresponding to the first female threaded hole 16 on the spindle 4 side, and a second fixing screw 70 is used to attach the spacer member 11 to the spindle 4. The spacer member 11 is attached to the tip of the spindle 4 by screwing the second fixing screw 70 through the second through-hole 68 of the spacer member 11 into the first female threaded hole 16 of the spindle 4. The tip of the spacer member 11 is further provided with a plurality of second female threaded holes (not shown) corresponding to the first through-hole 24 of the flange member 6, and the flange member 6 is attached to the tip of the spacer member 11 by screwing the first fixing screw 26 through the first through-hole 24 into the second female threaded holes of the spacer member 11.

[0027] The petal-shaped recess 58 in the first petal connecting member 52 and the petal-shaped projection 66 of the second petal connecting member 54 of the connecting mechanism 12 are configured as shown in Figure 3. In Figure 3, for ease of understanding, the first petal connecting member 52 is shown with a solid line and the second petal connecting member 54 is shown with a dashed line. As shown in Figure 3(a), the shapes of the petal-shaped recess 58 of the first petal connecting member 52 and the petal-shaped projection 66 of the second petal connecting member 54 correspond, and these petal-shaped projections 66 are formed to be somewhat smaller than these petal-shaped recesses 58.

[0028] With this configuration, when the second petal connecting member 54 is rotated relative to the first petal connecting member 52 in the direction indicated by arrow 70, for example, to position it at the release angle, as shown in Figure 3(a), the multiple petal-shaped recesses 58 on the first petal connecting member 52 side and the multiple petal-shaped protrusions 66 on the second petal connecting member 54 side align, and these petal-shaped protrusions 66 can be removed through these petal-shaped recesses 58.

[0029] Furthermore, when the second petal connecting member 54 is rotated relative to the first petal connecting member 52, for example in the direction indicated by arrow 72, to position it at the connecting angle, as shown in Figure 3(b), the multiple petal-shaped projections 66 on the second petal connecting member 54 side disengage from the multiple petal-shaped recesses 58 on the first petal connecting member 52 side in the circumferential direction, and the multiple petal-shaped projections 66 on the second petal connecting member 54 side engage with the annular inner flange 56 of the first petal connecting member 52, thereby achieving a connected state.

[0030] In this collet holding structure 2, a first rotation-preventing member 44 is provided as a first rotation-preventing means to prevent the relative rotation of the collet member 8 with respect to the flange member 6. In this embodiment, the flange member 6 is provided with a first mounting through hole 76 that penetrates radially, and a female thread portion is provided on a part of the inner circumferential surface of this first mounting through hole 76. A male thread portion is provided on a part of the outer circumferential surface of the first rotation-preventing member 74, and a pin portion 78 is provided at its tip. In addition, an elongated pin groove recess 80 is provided on the outer circumferential surface of the collet member 8.

[0031] With this configuration, the first rotation-preventing member 74 is screwed into the first mounting through-hole 76 of the flange member 6, and its tip pin portion 78 is inserted into the pin groove recess 80 of the collet member 8. This pin portion 78 prevents the collet member 8 from rotating relative to the flange member 6. Furthermore, since the pin portion 78 of the first rotation-preventing member 74 is inserted into the pin groove recess 80 so as to be movable in the axial direction (indicated by arrows 38 and 40), movement of the collet member 8 in the retraction direction (i.e., gripping direction) indicated by arrow 38, and movement in the release direction (i.e., gripping release direction) indicated by arrow 40 are permitted.

[0032] Furthermore, in the second usage configuration (with the spacer member 11 and the connecting mechanism 12 attached), a second rotation-blocking member 84 is provided as a second rotation-blocking means to prevent the relative rotation of the first petal connecting member 52 of the connecting mechanism 12 with respect to the spacer member 11. In this embodiment, the spacer member 11 is provided with a second mounting through-hole (not shown) that penetrates radially, and a female threaded portion is provided on the inner circumferential surface of this second mounting through-hole. A male threaded portion is provided on the outer circumferential surface of the second rotation-blocking member 84, and a pin portion 86 is provided at its tip. In addition, an elongated pin groove recess (not shown) similar to the pin groove recess 80 of the collet member 8 is provided on the outer circumferential surface of the first petal connecting member 52.

[0033] With this configuration, the second rotation-blocking member 84 is screwed into the second mounting through-hole (not shown) of the spacer member 11, and the pin portion 86 at its tip is inserted into the pin groove recess (not shown) of the first petal connecting member 52. This pin portion 86 prevents the first petal connecting member 52 from rotating relative to the spacer member 11. Furthermore, since the pin portion 86 of the second rotation-blocking member 84 is inserted into this pin groove recess so as to be movable in the axial direction (directions indicated by arrows 38 and 40), movement of the first petal connecting member 52 in the retraction direction (i.e., gripping direction) indicated by arrow 38, and movement in the release direction (i.e., gripping release direction) indicated by arrow 40 are permitted.

[0034] In this collet holding structure 2, the first usage configuration shown in Figure 4 is typically used. This first usage configuration is substantially the same as that of the conventional holding structure shown in Figure 5, but with the spacer member 11 and the connecting mechanism 12 omitted in Figure 2. Referring to Figures 2 and 4 (and structurally, also refer to Figure 5 which shows the conventional usage configuration), in this usage configuration, the flange member 6 is attached to the tip of the main shaft 4, and the collet member 8 is attached to the tip of the retraction member 10. The first fixing screw 74 is screwed into the first mounting through hole 76 of the flange member 6, and its pin portion 78 is inserted into the pin groove recess 80 on the collet member 8 side, thereby preventing relative rotation of the collet member 8 with respect to the flange member 6.

[0035] In this first mode of use, as can be seen from Figures 2 and 4, when the retraction member 10 is moved in the retraction direction, the collet member 8 is retracted in the direction indicated by arrow 38 (see Figure 2), and the enlarged tapered portion 34 on the collet member 8 side comes into contact with the enlarged tapered portion 36 on the flange member 6 side, tightening radially and creating a gripping state in which the workpiece (not shown) is gripped. When the retraction member 10 is moved in the push-out direction, the collet 8 is pushed out in the direction indicated by arrow 40, and the tightening state of the collet member 8 is released, resulting in a release state.

[0036] Furthermore, when switching from the first mode of use to the second mode of use shown in Figures 1 and 2 (in other words, a mode of use in which the collet member 8 can be easily replaced), for example, the first rotation-blocking member 74 is loosened so that its pin portion 78 retracts from the pin groove recess 80 on the collet member 8 side, and in this state the collet member 8 is rotated in the removal direction to remove the collet member 8 from the retraction member 10, and the first fixing screw 26 is loosened to remove the flange member 6 from the main shaft 4.

[0037] After removing the collet member 8 and flange member 6 in this manner, as shown in Figure 1, for example, the first petal connecting member 52 of the connecting mechanism 12 is attached to the tip of the retraction member 10, and the second petal connecting member 54 of the connecting mechanism 12 is attached to the rear end of the chuck member 8. Subsequently, the spacer member 11 is attached to the tip of the main shaft 4 by the second fixing screw 70, and the second rotation-preventing member 84 is screwed into the second mounting through hole (not shown) of the spacer member 11, and the pin portion 86 at its tip is inserted into the pin groove recess (not shown) of the first petal connecting member 52, thereby preventing the relative rotation of the first petal connecting member 52 with respect to the spacer member 11.

[0038] Subsequently, a flange member 6 is attached to the tip of the spacer member 11 by a first fixing screw 26, and the second petal connecting member 54 is connected to the first petal connecting member 52 through the insertion hole 22 of the flange member 6. As can be understood from Figures 3(a) and (b), this connection is made by first positioning the petal-shaped projection 66 of the second petal connecting member 54 inside the petal-shaped recess 58 of the first petal connecting member 52, and then rotating the second petal connecting member 54 by approximately 30 degrees in the direction indicated by arrow 72, for example, so that the petal-shaped projection 66 is positioned at an angle where it is away from the petal-shaped recess 58 of the first petal connecting member 52. By inserting it in this way and rotating it in a predetermined direction, the first petal connecting member 52 and the second petal connecting member 54 can be connected. Subsequently, the first rotation-preventing member 74 is screwed into the first mounting through-hole 76 of the flange member 6, as described above, and its pin portion 78 is inserted into the pin groove recess 80 on the collet member 8 side, thereby preventing the collet member 8 from rotating relative to the flange member 6.

[0039] In this second mode of use, as can be seen from Figure 2, when the retraction member 10 is moved in the retraction direction, the collet member 8 is retracted in the direction indicated by arrow 38 (see Figure 2) via the connecting mechanism 12 (first petal connecting member 52 and second petal connecting member 54), and the enlarged tapered portion 34 on the collet member 8 side comes into contact with the enlarged tapered portion 36 on the flange member 6 side, resulting in a gripping state. Furthermore, when the retraction member 10 is moved in the pushing direction, the collet member 8 is pushed out in the direction indicated by arrow 40, and the tightening state of the collet member 8 is released, resulting in a release state.

[0040] As explained above, in this collet holding structure 2, by attaching a spacer member 11 between the main shaft 4 and the flange member 6 in a normal collet holding structure, and by attaching a connecting mechanism 12 between the retraction member 10 and the collet member 8, it is possible to provide a collet holding structure in which the collet member 8 can be easily and quickly replaced. Furthermore, existing collet holding structures can be modified into highly practical structures that allow for easy replacement of the collet member 8. In this case, by preparing a collet member 8 with a second petal connecting member 54 attached to its rear end, it becomes possible to easily replace the collet member 8 with the second petal connecting member 54 without replacing the second petal connecting member 54.

[0041] Although one embodiment of the collet holding structure according to the present invention has been described above, the present invention is not limited to this embodiment, and various changes and modifications are possible without departing from the scope of the present invention.

[0042] For example, in the embodiment described above, the first petal connecting member 52 is configured to have a petal-shaped recess 58, and the second petal connecting member 54 is configured to have a petal-shaped projection 66. However, conversely, the first petal connecting member 52 may be configured to have a petal-shaped projection, and the second petal connecting member 54 may be configured to have a petal-shaped recess. [Explanation of symbols]

[0043] 2. Collet retention structure 4 spindle 6. Flange member 8. Collet Member 10 Retractable member 11 Spacers 12 Connection mechanism 22 Through hole 52 Second petal connecting member 54 Second petal connecting member 58 Petal-shaped recesses 66 Petal-like projections 74 First motion blocking member 84 Second motion blocking member

Claims

1. A collet holding structure for a machine tool comprising a spindle rotatably supported by the machine tool body, a flange member attached to the tip of the spindle, a collet member fitted into an insertion hole in the flange member, and a retraction member for retracting the collet member to the rear, A spacer member is configured to be attachable between the main shaft and the flange member, and a connecting mechanism is configured to be attachable between the retraction member and the collet member, and the axial lengths of the main shaft in the spacer member and the connecting mechanism correspond to each other. A collet holding structure for a machine tool, characterized in that, in a first mode of use, the flange member is attached to the spindle and the collet member is attached to the retracting member, and in a second mode of use, the flange member is attached to the spindle via the spacer member and the collet member is attached to the retracting member via the connecting mechanism.

2. A first female screw hole is provided on the tip surface of the main shaft, a first through hole is provided in the flange member corresponding to the first female screw hole, and a second through hole is provided in the spacer member corresponding to the first screw hole of the main shaft, as well as a second female screw hole corresponding to the first through hole of the flange member. The collet holding structure for a machine tool according to claim 1, characterized in that, in the first mode of use, the first fixing screw is screwed into the first female screw hole of the main spindle through the first through hole of the flange member, and in the second mode of use, the second fixing screw is screwed into the first female screw hole of the main spindle through the second through hole of the spacer member, and the first fixing screw is screwed into the second female screw hole of the spacer member through the first through hole of the flange member.

3. The tip of the retractable member is provided with a first female threaded portion, and the rear end of the collet member is provided with a first male threaded portion that is screwed into the first female threaded portion. The connecting mechanism includes a first connecting member attached to the retractable member and a second connecting member attached to the collet member, wherein the rear end of the first connecting member is provided with a second male threaded portion corresponding to the first female threaded portion of the retractable member, and the tip of the second connecting member is provided with a second female threaded portion corresponding to the first male threaded portion of the collet member. The collet holding structure for a machine tool according to claim 1, characterized in that, in the first mode of use, the first male threaded portion of the collet member is screwed into the first female threaded portion of the retracting member, and in the second mode of use, the second male threaded portion of the first connecting member is screwed into the first female threaded portion of the retracting member, and the second female threaded portion of the second connecting member is screwed into the first male threaded portion of the collet member.

4. The collet holding structure for a machine tool according to claim 3, characterized in that the flange member is provided with a first mounting through-hole extending in the radial direction, a first rotation-preventing member is attached through the first mounting through-hole, the first rotation-preventing member allows the collet member to move in the axial direction relative to the flange member and prevents the collet from rotating relative to the flange member, and the spacer member is provided with a second mounting through-hole extending in the radial direction, a second rotation-preventing member is attached through the second mounting through-hole in the second usage configuration, the second rotation-preventing member allows the first connecting member to move in the axial direction relative to the spacer member and prevents the first connecting member from rotating relative to the spacer member.

5. The collet holding structure for a machine tool according to claim 3, characterized in that the connecting mechanism is composed of a petal-shaped connecting mechanism, the first connecting member is a first petal connecting member, and the second connecting member is a second petal connecting member.

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