Tool holder and anti-rotation member

Abstract

To provide a tool holder capable of gripping a tap so as not to rotate relative to it even when a collet without a square hole is used. [Solution] A tool holder (1) includes a collet chuck body (10), a collet (20), and a rotation prevention member (40). The collet chuck body has a threaded hole portion (10a) with a male thread on its inner circumferential surface, a straight hole portion (10b) with a larger diameter than the threaded hole portion, and a tapered hole portion (10c) that continues to the straight hole portion and increases in diameter toward the tip, with these hole portions arranged in this order along the axial direction. The collet fits into the straight hole portion and the tapered hole portion and clamps the shank portion (61) of a tap (60). The rotation prevention member screws into the threaded hole portion and has a square hole portion (44) that non-rotatably receives the corner of the tap.

Description

[Technical Field]

[0001] The present invention relates to a tool holder and a rotation-preventing member, and more particularly to a tool holder for gripping a tap having a corner at the rear end of a shank portion, and a rotation-preventing member for preventing relative rotation of the tap. [Background technology]

[0002] A standard shape of a collet used in a tool holder is disclosed in Japanese Patent Laid-Open No. 2004-255474 (Patent Document 1). The collet in Patent Document 1 (hereinafter also referred to as a "standard collet") has a straight end portion and a tapered portion that expands in diameter toward the tip, and the tip of the tapered portion has a nut engaging portion that engages with a nut (fastening member) so as to be rotatable relative to the nut.

[0003] Such a standard collet has a cylindrical tool insertion hole that penetrates in the axial direction, and is configured to grip the shank portion of a cutting tool inserted into the tool insertion hole by tightening the tapered portion with a nut (fastening member). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-255474 A (Patent No. 3899324) Summary of the Invention [Problem to be solved by the invention]

[0005] Standard collets are highly versatile and can grip the shanks of various types of cutting tools (drills, reamers, end mills, etc.). However, dedicated collets have been used for taps used in "tapping," a process used to create internal threads in workpieces. Because taps are more prone to slipping during workpiece processing than other types of cutting tools, a rotation-prevention mechanism is required for the tap and collet. Specifically, taps have a rectangular prism-shaped corner at the rear end of the shank, and tap-specific collets have a square hole at the rear end that accepts the corner of the tap to prevent it from rotating.

[0006] Furthermore, in order to prevent the tap-specific collet itself from rotating relative to the collet chuck body, a rotation prevention mechanism between the collet chuck body and the collet may also be required. In this case, it was necessary to manufacture and store a collet chuck body specifically for taps, separate from the standard specification collet chuck body.

[0007] For this reason, there has been a demand for a technology that can adequately prevent the tap from rotating without using a collet specifically for taps or a collet chuck body specifically for taps, that is, even if a standard collet without a square hole is used.

[0008] The present invention has been made to solve the above-mentioned problems, and its object is to provide a tool holder that can hold a tap so that it cannot rotate relative to the tap even when a collet that does not have a square hole portion is used, and an anti-rotation member that can be applied to the tool holder. [Means for solving the problem]

[0009] A tool holder according to one aspect of the present invention is a tool holder for gripping a tap having a corner at the rear end of its shank, and includes a collet chuck body, a collet, and a rotation-preventing member. The collet chuck body has a threaded hole portion with a male thread on its inner circumferential surface, a straight hole portion with a larger diameter than the threaded hole portion, and a tapered hole portion that continues to the straight hole portion and increases in diameter toward the tip, with these hole portions arranged in this order along the axial direction. The collet fits into the straight hole portion and the tapered hole portion to clamp the shank portion of the tap. The rotation-preventing member screws into the threaded hole portion and has a square hole portion that non-rotatably receives the corner portion of the tap.

[0010] In one embodiment, the corner of the tap is located rearward of the collet, and the anti-rotation member is located rearward of the collet.

[0011] Preferably, the collet chuck body has an annular receiving surface formed at the boundary between the threaded hole portion and the straight hole portion and perpendicular to the axial direction. In this case, the anti-rotation member desirably includes a shank having an internal thread formed on its outer circumferential surface to be threaded onto the external thread, and a flange provided at the tip of the shank and abutting against the receiving surface in the attached state.

[0012] In another embodiment, the corner of the tap is located within an enlarged diameter hole formed in the distal end of the collet, and the tip of the anti-rotation member is disposed within the enlarged diameter hole of the collet.

[0013] Preferably, the square hole is provided so as to pass through the anti-rotation member in the axial direction.

[0014] Typically, the corner portion has a rectangular prism shape, and the rectangular hole portion has a square, elliptical, or groove shape when viewed in the axial direction.

[0015] It is also possible to provide the above-mentioned anti-rotation member as a single unit. [Effects of the Invention]

[0016] According to the present invention, even if a collet without a square hole is used, the tap can be gripped so as to be unable to rotate relative to the collet. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view schematically showing a tool holder according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram schematically illustrating an example of the structure of a tap. [Figure 3] 2A and 2B are diagrams schematically illustrating an example of the structure of the anti-rotation member according to the first embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view schematically showing a tool holder according to a second embodiment of the present invention. [Figure 5] FIG. 1 is a cross-sectional view schematically showing a tool holder equipped with a collet and a collet chuck body dedicated to tapping. [Figure 6] FIG. 10 is a cross-sectional view schematically showing a tool holder having a length adjustment screw provided in a threaded hole portion. [Figure 7] 10A and 10B are diagrams schematically illustrating an example of the structure of another cutting tool. DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

[0019] A tool holder according to an embodiment of the present invention grips a tap having a corner portion at the rear end of the shank portion.

[0020] <Tool holder outline> The schematic configuration of the tool holder 1 will be described with reference to Fig. 1. In Fig. 1, the dashed dotted line O is the axis of the tool holder 1, the arrow T indicates the front side in the axial direction (also referred to as the leading end side), and the opposite direction of the arrow T indicates the rear side in the axial direction (also referred to as the rear end side).

[0021] The tool holder 1 mainly comprises a collet chuck body 10, a collet 20 attached to the axial front side of the collet chuck body 10, and a clamping member 30 attached to the axial front side of the collet 20. When these components are assembled, the tool holder 1 grips a cutting tool 6. The collet 20 is typically a standard collet (standard collet) capable of clamping various types of cutting tools. The collet chuck body 10 has a shape and structure that allows the standard collet 20 to be attached. The collet chuck body 10 is also composed of a standard collet chuck body.

[0022] The collet chuck body 10 includes a shank portion 11, a flange 12 formed on the tip side of the shank portion 11, a cylindrical portion 13 extending from the flange 12 toward the tip side, and a tool mounting portion 14 extending from the cylindrical portion 13 toward the tip side for clamping a cutting tool 6. The collet chuck body 10 also has a through-hole 10h that communicates along the axial direction from the rear end side to the tip side. The shank portion 11 is the portion that is attached to the spindle of a machine tool. The flange 12 is the portion that is gripped when replacing the cutting tool 6. An annular step 15 is provided at the boundary between the tool mounting portion 14 and the cylindrical portion 13. Therefore, the outer diameter of the tool mounting portion 14 is smaller than the outer diameter of the cylindrical portion 13. A male thread 16 is formed on the outer peripheral surface of the tool mounting portion 14.

[0023] The through hole 10h of the collet chuck body 10 has an inner peripheral surface Female thread The tool holder 10 has a continuous (in this order along the axial direction) threaded hole portion 10a with a threaded hole 17 cut into it, a straight hole portion 10b with a larger diameter than threaded hole portion 10a, and a tapered hole portion 10c that continues to straight hole portion 10b and increases in diameter toward the tip. Threaded hole portion 10a is formed by the inner peripheral surface (cylindrical surface) of tubular portion 13 and extends axially with a constant diameter. Straight hole portion 10b and tapered hole portion 10c are formed by the inner peripheral surface of tool attachment portion 14. A standard collet 20 is removably fitted into straight hole portion 10b and tapered hole portion 10c. The threaded hole portion 10a will be described later.

[0024] Collet 20, which is a standard collet, has a cylindrical end portion 21 and a tapered portion 22 that expands in diameter toward the tip. Collet 20 has a tool insertion hole 20h that penetrates from the rear end to the tip along the axial direction. The inner circumferential surface of tool insertion hole 20h is formed by a single cylindrical surface of the same diameter or multiple cylindrical surfaces of different diameters.

[0025] The outer diameter of the tapered portion 22 increases toward the tip side, and the outer peripheral surface of the tapered portion 22 abuts against the inner peripheral surface of the tapered hole portion 10c of the above-mentioned collet chuck body 10. The outer peripheral surface of the end portion 21 abuts against the inner peripheral surface of the straight hole portion 10b of the collet chuck body 10.

[0026] A constricted portion (recess) 23 is formed on the outer peripheral surface of the tip end of collet 20. Collet 20 engages with the tip end of fastening member 30 at constricted portion 23 so as to be relatively rotatable. Collet 20 is provided with a slit (not shown) extending in the axial direction from the axial center of end portion 21 to the tip end of tapered portion 22. A plurality of slits are provided at equal intervals around the circumference.

[0027] The collet 20 reduces in diameter as the tool mounting portion 14 of the collet chuck body 10 is tightened by the fastening member 30, thereby clamping the cutting tool 6. The fastening member 30 is a cylindrical nut with a female thread 31 formed on its inner circumferential surface. The female thread 31 is threadedly engaged with the male thread 16 of the collet chuck body 10. The fastening member 30 has a protrusion 32 that engages with the necked portion 23 of the collet 20 so as to be rotatable relative to the necked portion 23.

[0028] The cutting tools 6 that can be held by the tool holder 1 according to this embodiment include drills, reamers, end mills, and other cutting tools that can conventionally be held by standard collets (hereinafter referred to as "other cutting tools"), as well as taps 60. Fig. 1 shows the state in which the tool holder 1 holds the tap 60. The tool holder 1 (collet chuck body 10) holding the tap 60 is attached to the spindle of a machine tool (not shown), and by synchronizing the rotation and feed of the spindle in the machine tool, tapping can be performed at a constant pitch.

[0029] <Example of tap structure> Unlike other cutting tools such as drills, the tap 60 has a corner 63 at the rear end of the shank 61 to prevent rotation. This is because the tap 60 may slip when subjected to excessive load during tapping (for example, when the workpiece is very hard or the pilot hole is small). An example of the structure of the tap 60 is shown in FIG. 2, and an example of the structure of another cutting tool 64 is shown in FIG. 7.

[0030] Fig. 2(A) is a side view of the tap 60, and Fig. 2(B) is a cross-sectional view taken along line IIB-IIB in Fig. 2(A). Note that the axis of the tap 60 is indicated by a dashed line in Fig. 2(A). The tap 60 has a shank portion 61 with a circular cross section, a cutting portion 62 provided at the tip of the shank portion 61, and a square pillar-shaped corner portion 63 provided at the rear end of the shank portion 61.

[0031] Fig. 7(A) is a side view of another cutting tool 64, and Fig. 7(B) is a cross-sectional view taken along line VIIB-VIIB in Fig. 7(A). The other cutting tool 64, such as a drill, has a shank portion 65 with a circular cross section and a cutting edge portion 66 provided at the tip of the shank portion 65. In the other cutting tool 64, the shank portion 65 does not have a corner at the rear end.

[0032] 2(B), the cross-sectional shape of the corner portion 63 is substantially square. The diagonal length L1 of the corner portion 63 as viewed in the axial direction is substantially the same as the outer diameter φ of the shank portion 61. Therefore, the length L2 of each side of the corner portion 63 is slightly shorter than the outer diameter φ of the shank portion 61.

[0033] <Collet and collet chuck body dedicated to tapping> For comparison with the tool holder 1 according to the present embodiment, Fig. 5 schematically shows a tool holder 100 equipped with a collet 120 dedicated to tapping and a collet chuck body 110. Fig. 5(A) is a cross-sectional view schematically showing a main part of the tool holder 100, which shows a comparison with the tool holder 1 according to the embodiment of the present invention. Fig. 5(B) is a schematic cross-sectional view showing an example of the structure of the collet 120 dedicated to tapping, which corresponds to a cross section taken along line IVB-IVB in Fig. 5(A).

[0034] Tapping collet 120 has a terminal end portion 121 with a hexagonal outer shape and a tapered portion 122 that expands in diameter toward the tip. Tapered portion 122 has a slit 122a formed along the axial direction. In addition, tool insertion hole 120h that passes through tapping collet 120 in the axial direction has a straight hole portion 120a formed mainly in tapered portion 122 and a square hole portion 120b formed in the rear end or terminal end portion 121 of tapered portion 122.

[0035] 5(B), the shape of square hole portion 120b when viewed in the axial direction is a substantially square shape similar to corner portion 63. Therefore, corner portion 63 of tap 60 fits snugly into square hole portion 120b in the attached state (in use state). This prevents relative rotation between tap-specific collet 120 and tap 60.

[0036] As shown in FIG. 5(A), the collet chuck body 110 has a straight hole portion 110a, a hexagonal hole portion (hereinafter referred to as the "hexagonal hole portion") 110b, and a tapered hole portion 110c along the axial direction. The tapered hole portion 110c is located at the tip end of the collet chuck body 110 and receives a tapered portion 122 of the tapping collet 120. The hexagonal hole portion 110b is formed between the tapered hole portion 110c and the straight hole portion 110a. In the attached state, the hexagonal end portion 121 of the tapping collet 120 fits snugly into the hexagonal hole portion 110b of the collet chuck body 110. This prevents relative rotation between the collet chuck body 110 and the tapping collet 120.

[0037] As described above, it has been common to use a collet chuck body 110 and collet 120 specifically designed for taps to prevent rotation of the tap 60. In contrast, the collet chuck body 10 and collet 20 according to this embodiment are of standard specifications that allow other cutting tools 64, such as drills, to be attached.

[0038] <Tap rotation prevention structure: embodiment 1> 1 again, the tool holder 1 according to this embodiment is mainly characterized in that an anti-rotation member 40 is provided in the threaded hole portion 10a of the collet chuck body 10 in order to prevent the tap 60 from rotating. In this embodiment, the collet 20 clamps only the shank portion 61 of the tap 60, and the anti-rotation member 40 holds the corner portion 63 of the tap 60 so that it cannot rotate.

[0039] First, the threaded hole portion 10a will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view schematically showing a tool holder 100A in which a length adjustment screw 150 is provided in the threaded hole portion 10a. The tool holder 100A has a collet chuck body 10 and a collet 20 having the same structure as in this embodiment, but the cutting tool 6 held by the tool holder 100A is a cutting tool 64 (a tool other than a tap, i.e., another cutting tool) that does not have a corner.

[0040] The length adjustment screw 150 is a member for adjusting the projection dimension of the cutting tool 64 from the collet chuck body 10, and is provided so as to be movable in the axial direction within the range of the screw hole portion 10a. Figure 6 As shown in FIG. 1, in the attached state, the rear end surface of the cutting tool 64 and the front end surface of the length adjusting screw 150 come into contact with each other.

[0041] The tool holder 1 according to this embodiment is provided with a rotation prevention member 40 that receives the corner portion 63 of the tap 60 in a non-rotatable manner by utilizing the threaded hole portion 10a for the length adjustment screw 150 formed in the collet chuck body 10.

[0042] An example of the structure of the anti-rotation member 40 will be described with reference to Fig. 3. Fig. 3(A) is a cross-sectional view of the anti-rotation member 40 cut along the axial direction, and Fig. 3(B) is a front view of the anti-rotation member 40 as seen from the tip end side (from the direction IIIB in Fig. 3(A)).

[0043] As shown in FIG. 3(A), the anti-rotation member 40 is Male thread The shaft portion 41 includes a shaft portion 41 having a flange portion 42 formed on the outer peripheral surface thereof, and a flange portion 43 provided at the tip end of the shaft portion 41. The shaft portion 41 is formed of a cylindrical portion extending with a substantially constant diameter along the axial direction. Male thread 42 is formed in the screw hole portion 10a of the collet chuck body 10 Female thread 17. In this way, the anti-rotation member 40 is screwed into the screw hole portion 10a.

[0044] The flange portion 43 is formed by an annular portion concentric with the shaft portion 41. In the attached state, the flange portion 43 is disposed in the straight hole portion 10b of the collet chuck body 10. The outer diameter of the flange portion 43 is slightly smaller than the diameter of the straight hole portion 10b. The flange portion 43 has a constant thickness in the axial direction.

[0045] As shown in FIGS. 3A and 3B, the anti-rotation member 40 has a square hole 44 that penetrates the flange 43 and the shaft 41 in the axial direction. When attached, the square hole 44 receives the square portion 63 in a non-rotatable manner. The shape of the square hole 44 as viewed in the axial direction is, for example, a substantially elliptical shape as shown in FIG. 3B. Specifically, the square hole 44 is defined by two parallel flat surfaces 44a and two arc-shaped surfaces 44b connecting the ends of the two flat surfaces 44a. In this case, two of the four outer surfaces of the square portion 63 (parallel to each other) are in surface contact with the two flat surfaces 44a of the square hole 44, preventing the square portion 63 from rotating within the square hole 44.

[0046] The rectangular hole 44 does not have to be a through hole, but may be a blind hole recessed rearward from the surface 43a of the flange 43.

[0047] Referring again to FIG. 1, in this embodiment, tap 60 is held in collet 20 with corner 63 entirely protruding rearward beyond collet 20. Collet 20 clamps only shank 61 of tap 60. Therefore, anti-rotation member 40 is disposed rearward beyond collet 20. The positions of anti-rotation member 40 and collet 20 in the axial direction do not overlap, and a slight gap is provided between anti-rotation member 40 and collet 20. Note that the two may also be in contact with each other.

[0048] In the attached state, the flange portion 43 of the anti-rotation member 40 abuts against an annular receiving surface 18 formed on the collet chuck body 10. The receiving surface 18 is formed at the boundary (step portion) between the threaded hole portion 10a and the straight hole portion 10b and is perpendicular to the axial direction. The receiving surface 18 is perpendicular to the rear end of the straight hole portion 10b and faces the front end side.

[0049] 1 and 3(A), the flange portion 43 has a surface 43a that faces (or contacts) the rear end surface of the collet 20, and a seating surface 43b that comes into surface contact with the receiving surface 18 of the collet chuck body 10. In this way, the seating surface 43b of the flange portion 43 comes into surface contact with the receiving surface 18, so that the rotation prevention member 40 can be securely coupled to the collet chuck body 10. Specifically, Female thread 17 and the shaft 41 Male thread Even if a slight gap occurs between the anti-rotation member 40 and the tap 60, tilting or displacement of the anti-rotation member 40 can be prevented when the tap 60 is operated. Therefore, tapping using the tap 60 can be performed with high precision.

[0050] Furthermore, in the attached state, a portion of the surface (front end surface) 43a of the flange portion 43 abuts (is in surface contact with) the (four) end surface portions 61a formed at the boundaries between the circular shank portion 61 and the corner portions 63 of the tap 60. This also improves the engagement between the anti-rotation member 40 and the tap 60 in the axial direction. Note that, although the present embodiment has shown an example in which the flange portion 43 is formed by a single annular portion surrounding the outer periphery of the shank portion 41, the present invention is not limited to this example and may be formed by, for example, a plurality of protrusions protruding radially from the shank portion 41.

[0051] As described above, according to this embodiment, even when a collet 20 without a square hole portion and a collet chuck body 10 without a hexagonal hole portion are used, by providing the anti-rotation member 40 that holds the corner portion 63 of the tap 60 non-rotatably, the tap 60 can be gripped so that it cannot rotate relative to the tap. In other words, the collet 120 and collet chuck body 110 dedicated to the tap can be eliminated.

[0052] As a result, it is possible to eliminate the need to change the collet chuck body and the collet when changing the cutting tool 6 from another cutting tool 64 to the tap 60. It is also possible to reduce the space required for managing parts in a factory and to reduce costs.

[0053] <Other examples of square hole shapes> The shape of the square hole portion 44 is not limited to the elliptical shape shown in Fig. 3(B). As shown in Fig. 3(D), the shape of the square hole portion may be substantially square (quadrilateral), which is the same as the shape of the corner portion 63 of the tap 60. The substantially square-shaped square hole portion 46 has four inner wall surfaces that contact (are in surface contact with) all four outer surfaces of the corner portion 63 in the attached state.

[0054] 3(C), the shape of the square hole may be a groove formed straight in the diameter direction of the flange portion 43. The square hole portion 45 is formed within the thickness range of the flange portion 43.

[0055] 3(B) and 3(C) is employed, it is possible to improve the workability of drilling holes in the anti-rotation member 40 compared to the square hole 46 shown in Fig. 3(D). Although it is desirable that the corner 63 of the tap 60 is constrained by two parallel sides of the square hole 44 (45) when viewed in cross section, it is sufficient that the corner 63 is prevented from rotating, and for example, the corner 63 may be constrained by three or more points (lines).

[0056] <Tap rotation prevention structure: embodiment 2> In this embodiment, a rotation prevention structure will be described for a tap (shank portion) with a smaller diameter than that of embodiment 1. Note that the basic configuration of the rotation prevention structure is the same as that of embodiment 1, so only the differences from embodiment 1 will be described below.

[0057] 4 is a cross-sectional view schematically showing a tool holder 1A according to the present embodiment. In the above-described first embodiment, the axial length of the shank portion 61 of the tap 60 is relatively long, so that the entire corner portion 63 can be disposed rearward of the collet 20, as shown in FIG. 1. In contrast, the axial length of the shank portion 61 of the tap 60A according to the present embodiment is relatively short, so that the corner portion 63 cannot be disposed rearward of the collet 20A of the standard specifications.

[0058] Therefore, in this embodiment, as shown in Figure 4, the tip portion 48 of the anti-rotation member 40A is inserted into the large diameter hole portion 20j at the rear end of the collet 20A, thereby making it possible to prevent the tap 60A from rotating.

[0059] Collet 20A is a standard collet for gripping a small-diameter shank portion 61, and does not have the square hole portion provided in tap-specific collet 120 (FIG. 5(A)). In this embodiment, tool insertion hole 20h of collet 20A has straight hole portion 20i formed in tapered portion 22, and large-diameter hole portion 20j formed in end portion 21 and having a larger diameter than straight hole portion 20i. Large-diameter hole portion 20j is a circular hole that is concentric with straight hole portion 20i.

[0060] In the attached state, the shank portion 61 of the tap 60A is located within the straight hole portion 20i, and the corner portion 63 is located within the large diameter hole portion 20j. The collet 20A clamps only the shank portion 61 of the tap 60A at the tapered portion 22. Note that because the end portion 21 of the collet 20A (the outer periphery of the large diameter hole portion 20j) is thin-walled, the tapered portion 22 is more likely to bend, which has the advantage of improving the gripping force on the tap 60A.

[0061] The anti-rotation member 40A in this embodiment does not have the flange portion 43 as in the first embodiment. Male thread The outer shell is formed by the shaft portion 41 on which the tip portion (48) of the shaft portion 41 is formed. Male thread 42 may not be formed. Male thread It is sufficient that the 42 is formed at least on the rear end portion (47) of the shaft portion 41.

[0062] The anti-rotation member 40A has a square hole 44 that penetrates the shaft 41 in the axial direction. In the attached state, a corner 63 of the tap 60A fits into the square hole 44. The shape of the square hole 44 when viewed in the axial direction may be, for example, a substantially elliptical shape, or a substantially square (rectangular) shape, as in the first embodiment. The square hole 44 may also be a blind hole recessed rearward from the tip end surface of the shaft 41.

[0063] In the attached state, the anti-rotation member 40A has a rear end 47 that screws into the threaded hole 10a of the collet chuck body 10, and a front end 48 that protrudes forward from the threaded hole 10a and is located within the large diameter hole 20j of the collet 20A. In other words, the anti-rotation member 40A is disposed across the threaded hole 10a and the straight hole 10b. A corner 63 of a tap 60A is inserted into the front end 48 of the anti-rotation member 40A.

[0064] The outer diameter of the anti-rotation member 40A (shaft 41) is set to the same as that of the large diameter hole of the collet 20A. 20 than the diameter of j Small An annular gap is formed between the tip end 48 of the anti-rotation member 40A and the end end 21. The shaft 41 of the anti-rotation member 40A does not have to have the same outer diameter from one end to the other in the axial direction, and the outer diameter of the tip end 48 may be smaller than the outer diameter of the rear end 47.

[0065] In this way, even if corner 63 of tap 60A cannot be made to protrude rearward beyond the collet, tap 60A can be prevented from rotating by inserting tip 48 of anti-rotation member 40A into large-diameter hole 20j of collet 20A. Furthermore, because tip 48 of anti-rotation member 40A and end 21 of collet 20A do not contact each other, tap 60A can be prevented from rotating without impairing the gripping function of collet 20A.

[0066] Since the anti-rotation member 40A in this embodiment does not have the flange portion 43 as in the first embodiment, it is possible to finely adjust the range of the rear end portion 47 that screws into the threaded hole portion 10a, thereby allowing fine adjustment of the protruding dimension of the tap 60A.

[0067] <Other> The collet chuck body 10 and collet 20 used in this embodiment may be of specifications (standard specifications) that can be shared with other cutting tools 64, and are not limited to known types, as a matter of course.

[0068] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0069] 1, 1A tool holder, 6 cutting tool, 10 collet chuck body, 10a screw hole portion, 10b straight hole portion, 10c tapered hole portion, 18 receiving surface, 20, 20A collet, 20j large diameter hole portion, 40, 40A anti-rotation member, 41 shaft portion, 42 Male thread , 43 flange part, 44,45,46 square hole part, 60,60A tap, 61 shank part, 62 cutting part, 63 square part.

Claims

1. A tool holder for holding a tap having a corner portion at the rear end of a shank portion, a collet chuck body having a threaded hole portion with a female thread cut on its inner peripheral surface, a straight hole portion having a diameter larger than that of the threaded hole portion, and a tapered hole portion connected to the straight hole portion and increasing in diameter toward the tip, which are provided in this order along an axial direction; a collet that fits into the straight hole portion and the tapered hole portion and clamps the shank portion of the tap with the corner portion protruding rearward; a rotation prevention member disposed rearward of the collet, threadedly engaged with the threaded hole, and having a square hole portion that non-rotatably receives the square portion of the tap; the collet chuck body has an annular receiving surface formed at a boundary between the threaded hole portion and the straight hole portion and perpendicular to an axial direction, the anti-rotation member includes a shaft portion having an outer peripheral surface formed with a male thread that screws into the female thread, and a flange portion that is provided at a tip end of the shaft portion and abuts against the receiving surface in an attached state, A tool holder, wherein a surface of the flange portion abuts against an end face portion formed at the boundary between the shank portion and the corner portion of the tap.

2. 2. The tool holder according to claim 1, wherein the square hole portion is provided so as to pass through the anti-rotation member in the axial direction.

3. The corner portion has a quadrangular prism shape, 2. The tool holder according to claim 1, wherein a shape of the rectangular hole portion as viewed in the axial direction is defined by two flat surfaces that are parallel to each other and two arc-shaped surfaces that connect end portions of the two flat surfaces.

4. The corner portion has a quadrangular prism shape, 2. The tool holder according to claim 1, wherein the shape of the rectangular hole portion when viewed in the axial direction is a square or groove shape.

5. the collet is capable of selectively holding the tap and another cutting tool that does not have a corner at its rear end, 2. The tool holder according to claim 1, wherein the threaded hole of the collet chuck body is selectively provided with the anti-rotation member and a length adjusting screw that abuts against a rear end surface of the other cutting tool.

6. A rotation-preventing member for preventing relative rotation of a tap having a corner at the rear end of a shank portion, the rotation-preventing member being applied to a tool holder having a collet chuck body having a threaded hole portion with an internal thread on its inner peripheral surface, a straight hole portion having a diameter larger than that of the threaded hole portion, and a tapered hole portion connected to the straight hole portion and increasing in diameter toward the tip, which are arranged in this order along an axial direction, the tap is held by a collet that fits into the straight hole portion and the tapered hole portion in a state where the corner portion protrudes rearward, a shaft portion having an outer peripheral surface on which a male screw thread is formed to be threadedly engaged with the female screw; a flange portion provided at the tip end of the shaft portion, the flange portion abutting against an annular receiving surface formed at a boundary between the threaded hole portion and the straight hole portion and perpendicular to the axial direction in an attached state; a square hole portion that non-rotatably receives the corner portion of the tap, A rotation-preventing member in which the surface of the flange portion abuts against an end face portion formed at the boundary between the shank portion and the corner portion of the tap in an attached state.

Images