JP2001079723A - Tool holder and tool mounting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid lowering of holding rigidity caused by a fitting clearance and to carry out double constraint with comparatively low working precision in the case of constituting a fitting part against a main spindle of a double constraint type tool holder of a plural number of members. SOLUTION: A fitting projected part 60 of this tool holder 10 is made hollow, and a plural number of grooves 76 a cross-section shape of which is semi-circular and extending along the axial direction are formed with equal angular intervals on an inside of a peripheral wall of the fitting projected part 60. A thin groove bottom 78 and a thick bank part 80 are alternately formed on the peripheral wall. Consequently, it is possible to realize double constraint by absorbing a dimensional error of the fitting projected part 60 and a fitting hole 18 by making the fitting projected part 60 easy to deform in the peripheral direction while avoiding lowering of flexural rigidity of the fitting projected part 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool holder and a tool mounting device for mounting a processing tool on a machine tool.

[0002]

2. Description of the Related Art As a kind of tool holder, there is a tool holder having a fitting projection fitted into a fitting hole of a tool holding shaft such as a main shaft of a machine tool. A typical example is a tool holder having a tool shank defined in JIS B 6339.
The fitting projection of the tool holder has an outer peripheral surface that is a 7/24 taper. On the other hand, a fitting hole having an inner peripheral taper surface corresponding to the outer peripheral taper surface is formed in the tool holding shaft of the machine tool. The tool holder is attached to the tool holding shaft by being tightly fitted to the peripheral taper surface.

[0003] Further, in the microfilm of Japanese Utility Model Application No. 60-23900, a two-sided constraint type tool holder is described. In this tool holder, the outer peripheral taper surface of the tool holder and the inner peripheral taper surface of the tool holding shaft are tightly fitted to each other, and the first end surface of the tool holder is brought into contact with the second end surface of the tool holding shaft. Thus, two-sided constraint is realized.
Specifically, the fitting projection of the tool holder to the tool holding shaft is
The tapered sleeve has an outer peripheral tapered surface and a straight fitting portion fitted to the tapered sleeve so as to be relatively movable in the axial direction. The straight fitting portion has a pull stud provided at one end thereof, and the other end is integrally connected to a flange having a first end surface. A plurality of compression coil springs are disposed between the flange and the tapered sleeve as elastic members for urging the two in a direction in which they are always separated from each other. Therefore, when the pull stud is pulled into the fitting hole and the first end face is brought into contact with the second end face,
The outer peripheral taper surface is brought into close contact with the inner peripheral taper surface by the elastic force of the compression coil spring, and the two-sided constraint is realized. If the processing tool is held on the tool holding shaft via the two-face constraint type tool holder, the processing tool can be held with high rigidity.

[0004]

However, since the fitting projection of the tool holder has a tapered sleeve and a straight fitting part that slide with each other, the fitting clearance between the two is provided. As a result, the holding rigidity of the working tool cannot be reduced, and it cannot be said that it is still sufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to realize a two-sided constraint while avoiding a decrease in the holding rigidity of a working tool due to the above-described clearance. According to the present invention, a tool holder and a tool mounting device of the following aspects can be obtained. As in the case of the claims, each aspect is divided into sections, each section is numbered, and if necessary, the other sections are cited in a form in which the numbers are cited. This is for the purpose of facilitating the understanding of the present invention, and should not be construed as limiting the technical features and combinations thereof described in the present specification to the following embodiments. Further, when a plurality of items are described in one section, it is not always necessary to adopt all of the items together, and it is also possible to take out and adopt only some of the items. (1) An end face, a fitting projection that extends in a direction perpendicular to the end face and forms an outer peripheral tapered surface whose diameter gradually decreases as the outer peripheral face moves away from the end face, and a side opposite to the fitting projection with respect to the end face. A tool holder provided with a tool holding portion for holding a processing tool, wherein the fitting protrusion is hollow, and a thin, elastically deformable peripheral wall of the hollow fitting protrusion is provided. Easy portions and hardly deformable portions that protrude inward in the radial direction with respect to the easily deformable portions and that are hard to elastically deform are each extended substantially in the axial direction and alternately three or more in the circumferential direction. A tool holder characterized by being formed (claim 1). In the tool holder described in this section, since the fitting projection is formed integrally, there is no decrease in holding rigidity due to the fitting clearance as in the conventional two-face restraint type tool holder. The fitting protrusion is easily deformed in the circumferential direction (elastic deformation with a reduced diameter, hereinafter referred to as reduced diameter) by the formation of the easily deformable portion. Since the dimensional error with the hole can be absorbed, the two-sided constraint can be realized without increasing the processing accuracy so much. In addition, the fitting projection is formed with a difficult-to-deform portion extending substantially in the axial direction, whereby the bending rigidity of the fitting projection is maintained at a high level. Can be kept sufficiently high. The easily deformable portion and the hardly deformable portion are desirably formed continuously from the large diameter portion to the small diameter portion of the outer peripheral tapered surface. The ratio of the easily deformable portion and the hardly deformable portion in the circumferential direction may be the same or may be larger. Further, the ratio of the easily deformable portion and the hardly deformable portion in the circumferential direction may be different between the large diameter portion and the small diameter portion of the fitting projection. For example, when the taper of the outer peripheral taper surface is equal to the taper of the inner peripheral taper surface, the large diameter portion and the small diameter portion have the same diameter reduction amount, and the small diameter portion has a higher deformation rate. Is desirably increased. (2) The tool holder according to (1), wherein the easily deformable portions are formed at equal angular intervals. If the easily deformable portions are formed at equal angular intervals, the elastic deformation of the fitting protrusions occurs substantially uniformly in the circumferential direction, and the fitting protrusions are reduced in diameter favorably. (3) On the inner peripheral surface of the peripheral wall, three or more grooves each having a substantially semicircular cross section formed along a plane including the center line of the fitting protrusion are formed, and the bottom of each of the grooves is formed. The tool holder according to the above mode (1) or (2), wherein portions to be formed each constitute the easily deformable portion, and portions between adjacent grooves form the hardly deformable portions. In this tool holder, since the thickness of the peripheral wall gradually increases from the easily deformable portion to the adjacent hardly deformable portion, the thickness of the peripheral wall rapidly changes at the boundary between the easily deformable portion and the hardly deformable portion. Compared to the case, stress concentration is less likely to occur at the boundary. Also,
The semicircular groove can be easily formed by machining. (4) A pull stud having a male screw portion at the tip is made to penetrate the hollow fitting projection in the axial direction, and into a female screw hole formed at a portion of the tool holder closer to the tool holding portion than the end face, The male thread is screwed (1) or
The tool holder according to any one of the above aspects (3) (Claim 2). Since the fitting projection of the tool holder is hollow, it is difficult to form a female screw hole for screwing the pull stud as in a normal tool holder. further,
If the pull stud is screwed into the portion where the easily deformable portion is formed, the pull stud may hinder the deformation of the portion. Therefore, it is desirable that the female screw hole for screwing the male screw portion of the pull stud is formed in a portion where the easily deformable portion is not formed. (5) a first end surface, and a first fitting portion extending in a direction perpendicular to the first end surface, and abut on the fixing member fixedly provided on the tool holding shaft of the machine tool and the first end surface. A second end surface, a second fitting portion extending in a direction perpendicular to the second end surface and fitting with the first fitting portion, and the second fitting portion is opposite to the second fitting portion with respect to the second end surface. A tool mounting device including a tool holder having a tool holding portion provided to hold a processing tool, wherein one of the first fitting portion and the second fitting portion includes the first and the second fitting portions. A second end surface and an opening that opens to an end surface corresponding to one of the second end surface, the inner peripheral surface is a fitting hole that forms an inner peripheral tapered surface whose diameter decreases as the distance from the opening, the first fitting portion And the other of the second fitting portion extends perpendicularly from the end surface corresponding to the other side, and the outer peripheral surface is formed on the inner peripheral taper surface. A thin, easily deformable portion, a deformable portion, and a thin-walled easily deformable portion formed on the peripheral wall forming at least one of the inner peripheral taper surface and the outer peripheral taper surface. Are hardly elastically deformed and protrude in the radial direction with respect to each other.
A tool mounting device, wherein the tool mounting device is formed by at least one piece. In the tool mounting device described in this section,
At least one of the fitting hole having the inner peripheral tapered surface and the fitting protrusion having the outer peripheral tapered surface is formed by a peripheral wall having an easily deformable portion and a hardly deformable portion. In the case where the fitting protrusion is formed by a circumferentially elastically deformable peripheral wall having an easily deformable portion and a hardly deformable portion, the same effect as the fitting protrusion in the tool holder described in (1) is achieved. can get. When the fitting hole is formed by a peripheral wall that is easily elastically deformed in the circumferential direction, the diameter of the fitting hole is enlarged (referred to as diameter expansion). When both the fitting protrusion and the fitting hole are formed by a circumferential wall that is easily elastically deformed in the circumferential direction, both diameter reduction and diameter expansion occur. In this case, even if the dimensional error between the fitting hole and the fitting projection is large, the dimensional error can be absorbed. The fitting protrusion may be provided on the fixing member or the tool holder, and the fitting hole is provided on the opposite member. (6) The tool mounting device according to the above mode (5), wherein the first fitting portion is the fitting hole, and the second fitting portion is the fitting projection. (7) The tool mounting device according to (6), wherein the easily deformable portion and the hardly deformable portion are provided on the tool holder. (8) The tool mounting device according to the mode (6) or (7), wherein the easily deformable portion and the hardly deformable portion are provided on the fixing member. (9) The tool attachment device according to the above mode (5), wherein the first fitting portion is the fitting projection, and the second fitting portion is the fitting hole. (10) On the surface of the peripheral wall opposite to the outer peripheral taper surface or the inner peripheral taper surface, three grooves each having a substantially semicircular cross section are respectively formed along a plane including a center line of the fitting projection. The portions formed above and forming the bottoms of the grooves respectively constitute the easily deformable portions, and the portions between the adjacent grooves constitute the hardly deformable portions (5) to (9). The tool mounting device according to any one of the above. In this tool mounting device, the same effect as the tool holder described in the item (3) can be obtained. (11) The tool mounting device according to the above mode (10), wherein the thickness of the easily deformable portion is made thicker on the smaller diameter side of the outer peripheral tapered surface or the inner circumferential tapered surface on the larger diameter side. In the tool mounting device described in this section, for example, by increasing the thickness of the easily deformable portion on the small diameter side of the tool holder, a fitting portion for fitting the pull stud is formed, and the pull stud is formed. It is easy to guide.

[0006]

FIG. 1 shows a tool holder 10 according to one embodiment of the present invention. This tool holder 1
Numeral 0 is used for attaching / detaching a processing tool such as a cutting tool to / from a spindle 12 of a machine tool indicated by a two-dot chain line. The main shaft 12 has a center hole 16 opening in the front end face 14.
Has a fitting hole 18 into which the tool holder 10 is fitted. The inner peripheral surface of the fitting hole 18 is a tapered inner peripheral surface whose diameter decreases as the distance from the front end surface 14 increases, and the taper is 7/24. Drive keys 20 are provided at two positions on the front end face 14 that are separated from each other in the diameter direction. The drive key 20 is projected forward from the end face 14 of the main shaft 12 in the axial direction.

A flange portion 22 is formed at an intermediate portion in the axial direction of the tool holder 10 and protrudes radially outward.
Both end surfaces of the flange portion 22 are formed at right angles to the axis, and a rear end surface 24 of the two end surfaces which faces the main shaft 12 abuts on the front end surface 14 so that the main shaft 1 of the tool holder 10 is formed.
2 is defined. Engagement grooves 26 extending in the axial direction from the rear end surface 24 are formed at two locations in the flange portion 22 that are separated in the diameter direction. By the engagement between the engagement groove 26 and the drive key 20, torque is transmitted from the main shaft 12 to the tool holder 10. Further, an annular groove 28 is formed along the outer periphery of the flange portion 22. The annular groove 28 is a V-shaped groove in which the width of both side surfaces decreases toward the bottom.

A cylindrical tool holder 30 extends in the axial direction from the front end face of the flange 22 opposite to the main shaft 12. Keys 32 are provided at two locations on the front end face of the flange portion 22 that are separated in the diametrical direction. The key 32 is a key groove 3 provided in the flange portion 22 in the same phase as the engagement groove 26.
4 is fixed by bolts. The tool holding portion 30 has a female screw hole 36 passing through the center thereof. The tool holding unit 30 in the present embodiment is suitable for holding a face mill 38 (shown by a two-dot chain line) as a cutting tool, and includes a through hole 40 formed in the front mill 38 and a tool holding unit 30. And are fitted,
The key 32 and the key groove 42 formed in the front milling cutter 38 are engaged with each other and fixed by the set bolt 44. The male screw part 46 of the set bolt 44 has the female screw hole 3
6, the flange portion 48 of the set bolt 44 is brought into contact with the counterbore bottom surface 50 of the front milling cutter 38, and the front milling cutter 38 is fixed to the tool holder 10.

A pull stud 52 is screwed into a portion of the female screw hole 36 opposite to the side where the set bolt 44 is screwed. The pull stud 52 has a substantially cylindrical shape, is provided with a male screw portion 54 screwed into the female screw hole 36 at one end, and an engagement portion 5 with which the draw bar of the machine tool is engaged at the other end.
8 are provided. The pull stud 52 has a fitting projection 60.
And the engaging portion 58 protrudes from the fitting protrusion 60. The front end of the shaft of the pull stud 52 has a shoulder surface 6.
The pull stud 52 is fixed to the tool holder 10 by the shoulder surface 66 contacting the opening peripheral portion 68 of the female screw hole 36.

The fitting portion 60 extends axially from the rear end surface 24 of the flange portion 22, and the outer peripheral surface thereof decreases in diameter as the distance from the end surface 24 increases. An outer peripheral taper surface 72 having a minimum diameter at the distal end portion 70 is formed. The taper of the outer peripheral taper surface 72 is 7/24. The fitting projection 60 is hollow. Specifically, a shape in which a bottomed hole 74 that opens at the tip end portion 70 and extends in the axial direction and a plurality of grooves 76 that extend substantially along the outer peripheral tapered surface 72 on the peripheral wall of the bottomed hole 74 is used. are doing. Therefore, the peripheral wall of the fitting projection 60 has at least the inner diameter of the bottomed hole 74 and is configured not to contact the pull stud 52 provided through the fitting projection. The bottomed hole 74 and the groove 76 are formed in the flange portion 22.
, And communicates with the female screw hole 36.

As shown in FIG. 2, the groove 76 has a partially circular cross section that is convex outward in the radial direction, and the grooves 76 are formed at equal angular intervals.
Individually formed. The thickness of the peripheral wall at the groove bottom 78 of the groove 76 is a thickness that is easily elastically deformed in the circumferential direction, and the thickness of the peripheral wall at the bank 80 between the adjacent grooves 76 is a thickness that is difficult to elastically deform. . In the present embodiment,
Since the groove 76 is slightly more inclined than the outer peripheral tapered surface 72, the thickness of the peripheral wall at the groove bottom 78 is reduced
It is gradually increased toward. Since the radius of the groove 76 is constant, as shown in FIG. 3, the overlapping portion of the groove 76 increases as approaching the tip portion 70, and
Is reduced so as to approach the thickness at the groove bottom 78.

Processing of the peripheral wall of the fitting projection 60 will be described. First, a hole inclined with respect to the axis is formed in the fitting protrusion 60 by a drill. Eight cylindrical holes are formed in a partially overlapping state, and the material remaining in the center is then cut and removed with a large diameter drill or cutting tool. A part of the hole formed by the drill becomes the groove 76, and a part from which the material remaining in the center is removed becomes the bottomed hole 74. The fitting projection may be formed by another method, such as being formed hollow by casting.

Next, the attachment and detachment of the tool holder 10 with respect to the main shaft 12 will be described. When the tool holder 10 is detached from the main shaft 12, the fitting projection 60 retains its size when formed. When the fitting projection 60 is inserted into the fitting hole 18, first, the outer peripheral tapered surface 72 abuts on the inner peripheral tapered surface 18, and the engaging portion 58 is located in a drawbar gripping device (not shown). Become. In this state, when the drawbar is retracted, the groove bottom 78 is mainly contracted in the circumferential direction, and the diameter of the fitting projection 60 is reduced.
Eventually, the rear end face 24 and the front end face 14 are strongly pressed, and the axial movement of the tool holder 10 with respect to the main shaft 12 stops. The close contact between the rear end face 24 and the front end face 14 and the tight fit between the outer tapered surface 72 and the inner tapered surface 18 are both achieved, and the two-sided constraint of the tool holder 10 is realized.

In the present embodiment, since the fitting projection 60 of the tool holder 10 is integrally formed, the holding rigidity due to the fitting clearance between the components is different from the conventional case where the fitting projection 60 is formed by a plurality of components. There is no drop. In addition, since the fitting protrusion 60 is easily deformed, the fitting protrusion 60 and the fitting hole 1 are not easily deformed.
8 can be absorbed, and the two-sided constraint can be realized without increasing the processing accuracy so much. In addition, the bank 80 extending in the axial direction is thickened,
Since the bending rigidity of 0 is maintained high, the rigidity of the tool holder 10 itself is also maintained high, and it is possible to easily achieve the securing rigidity of the cutting tool by the main shaft 12 via the tool holder 10.

As is apparent from the above description, in the present embodiment, the fitting projection 60 constitutes the “fitting projection or the second fitting part” in the claims, and the fitting hole 18 is formed. The “first fitting part” is formed, the front end of the main shaft 12 forms a “fixing member”, the groove bottom 78 forms a “deformable part”, and the bank 80 forms a “deformable part”. , The rear end face 24 constitutes an “end face or a second end face”, and the front end face 14 constitutes a “first end face”.
Is composed.

In the above embodiment, the groove 76 is inclined more than the outer tapered surface 72, but may be inclined in the same direction as the outer tapered surface 72.
Furthermore, in the present embodiment, eight grooves 76 are formed at equal angular intervals, and the grooves 76 are formed substantially adjacent to each other in the large diameter portion. However, the number of grooves is reduced to reduce the interval between the grooves. May be larger. It is sufficient that three or more grooves are formed,
It is desirable that six or more be formed.

Next, a second embodiment will be described. Since the second embodiment has almost the same portions as the first embodiment, only different portions will be described. In the first embodiment, the taper of the outer peripheral taper surface 72 and the taper of the inner peripheral taper surface 18 are both 7/24. For this reason, the deformation amount is equal between the base end portion having a large diameter near the rear end surface 24 and the front end portion having a small diameter. In the elastic deformation region, the deformation rate at the base end cannot be sufficiently increased. On the other hand, in this embodiment, the taper of the outer peripheral taper surface is slightly increased while the taper of the inner peripheral taper surface 18 remains 7/24. As a result, in the fitting protrusion having the outer peripheral tapered surface, the deformation amount at the time of fitting becomes larger as the base end portion is closer to the end surface 24 and has a larger diameter, and the deformation amount becomes smaller at the tip portion having a smaller diameter. . The amount of deformation can be changed in the axial direction in proportion to the diameter of the fitting protrusion, and the deformation rates of the base end and the front end can be equalized. In other words, the tight fitting at the base end of the fitting projection 60 can be sufficiently strengthened.

The embodiment of the present invention has been described above, but this is an exemplification, and the present invention is not limited to the embodiment described in the section [Problems to be Solved by the Invention, Means for Solving the Problems, and Effects of the Invention]. And various modifications and improvements based on the knowledge of those skilled in the art.

[0019]

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a tool holder according to an embodiment of the present invention.

FIG. 2 is a II-II cross section in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

[Explanation of symbols]

10: Tool holder 12: Spindle 14: Front end face
18: fitting hole 24: rear end face 60: fitting projection
72: outer peripheral taper surface 76: groove 78: groove bottom 80: embankment

Claims (3)

[Claims] An end face, a fitting projection extending in a direction perpendicular to the end face, and having an outer peripheral tapered surface whose diameter gradually decreases as the outer peripheral face moves away from the end face, and a fitting projection opposite to the end face. A tool holder provided on the side and holding a processing tool, wherein the fitting projection is hollow, and the peripheral wall of the hollow fitting projection is thin and elastically deformed. Three easily deformable portions and three hardly deformable portions that protrude radially inward with respect to the easily deformable portions and that are hardly elastically deformed extend substantially in the axial direction and alternately in the circumferential direction. A tool holder characterized by being formed as described above. 2. A pull stud having a male thread portion at a tip,
2. The male screw part is axially penetrated through the hollow fitting projection, and the male screw part is screwed into a female screw hole formed in a part of the tool holder closer to the tool holding part than the end face. Tool holder as described. 3. A fixing member having a first end surface and a first fitting portion extending in a direction perpendicular to the first end surface, the fixing member being fixedly provided on a tool holding shaft of a machine tool; A second end face that abuts, a second fitting part that extends in a direction perpendicular to the second end face and fits with the first fitting part, and the second fitting part is opposite to the second end face. A tool holder having a tool holder provided on the side and holding a processing tool, and any one of the first fitting portion and the second fitting portion,
It is a fitting hole having an opening that opens to an end surface corresponding to one of the first and second end surfaces, and an inner peripheral taper surface whose diameter decreases as the inner peripheral surface moves away from the opening, The other of the one fitting portion and the second fitting portion extends in a direction perpendicular to the end surface corresponding to the other portion, and a fitting protrusion that forms an outer peripheral taper surface whose outer peripheral surface corresponds to the inner peripheral taper surface, In addition, a thin-walled easily deformable portion which is easily elastically deformed on the peripheral wall forming at least one of the inner peripheral tapered surface and the outer peripheral tapered surface, and which protrudes radially with respect to the easily deformable portion, is elastically deformed with thick wall A tool mounting device, wherein three or more hardly deformable portions are formed alternately in the circumferential direction in a state of extending substantially in the axial direction.