JP7261285B1 - tap holder - Google Patents

Abstract

An object of the present invention is to provide a tap holder capable of absorbing not only an error in the axial direction but also an error in the rotational direction. A tap holder (1) comprises a tap holder body (2) attached to a spindle of a machine tool, a float shaft (4) held by the tap holder body with an axial clearance and a rotational clearance, and a tap. A locking part (3) that is fixed to the holder body and defines the axial clearance of the float shaft, a tap holding part (6) that holds the tap and is attached to the tip of the float shaft in the axial direction, and a tap holder. micro-movement absorbing means (8) for absorbing axial and rotational micro-movements of the float shaft with respect to the body. [Selection drawing] Fig. 2

Description

The present invention relates to a tool holder attached to a spindle of a machine tool, and more particularly to a tap holder for attaching and fixing a tap.

2. Description of the Related Art Conventionally, it is known that tapping is performed by synchronous control that synchronizes the rotation of a spindle and the feed of a spindle using an NC device. In such synchronous control, if for some reason the rotation of the spindle of the machine tool and the shaft feed do not synchronize and become inconsistent, the ridgeline of the screw thread is shaved and the diameter of the female screw increases or the screw thread becomes thinner. Inconvenience such as In particular, there was a concern that the inconvenience would become more pronounced due to the increase in size and aging of machine tools.

Therefore, as a technique for absorbing the synchronization error between the rotation of the spindle and the axis feed, for example, the tap holder described in Japanese Patent Application Laid-Open No. 2012-91251 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2008-12613 (Patent Document 2) It has been known.

Patent Document 1 discloses a tap holder including a shank member chucked by a tool holder and a tap holder body that holds a tap at one end and is attached to the shank member so that it can move forward and backward. . This tap holder is provided with an elastic member that biases toward the front end in the axial direction and an elastic member that biases toward the rear end in the axial direction in the axial gap between the shank member and the tap holder body. Axial errors can be absorbed.

Patent Document 2 discloses a tap holder consisting of a tap collet that holds a tap at one end and a tapper body that receives the tap collet and non-rotatably grips and fixes the tap collet. An elastically deformable resin ball is held in the through hole of the tapper body with almost no gap. The resin ball protrudes into the concave groove of the tap collet and presses so as to be in close contact with the concave groove. As a result, the tap collet is coupled with the tapper body and restricted from moving in the axial direction.

JP 2012-91251 A JP 2008-12613 A

During the tapping operation, the rotating operation and the axial feeding operation proceed simultaneously. Therefore, if there is an error in the axial direction, there is also an error in the rotational direction. Since the tap holder of Patent Document 1 is provided with an elastic member in the axial gap between the shank member and the tap holder main body, it is possible to absorb an axial synchronization error. However, it cannot absorb synchronization errors in the direction of rotation.

Further, in the tap holder of Patent Document 2, since the resin ball is provided in the through hole of the tapper body, it is possible to absorb a very small amount of movement in the axial direction, but it is possible to absorb the synchronization error in the rotational direction. It is not possible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tap holder capable of absorbing not only axial errors but also rotational errors.

For this purpose, the tap holder according to one aspect of the present invention is held by the tap holder body attached to the main shaft of the machine tool and the tap holder body with an axial clearance and a rotational clearance, and rotates integrally with the tap holder body. A float shaft, a locking portion that is fixed to the tap holder body and regulates the amount of movement of the float shaft in the axial direction, a tap holding portion that holds the tap and is attached to the tip of the float shaft in the axial direction, and the tap A micro-movement absorbing means for absorbing micro-movements of the float shaft relative to the holder body in the axial and rotational directions.

Preferably, the micro-movement absorbing means includes an elastic body that extends so as to pass through the interface between the tap holder body and the float shaft and exerts elastic force in the axial and rotational directions.

Preferably, the elastic body is a cylindrical body having an axis extending in the radial direction of the tap holder body.

Preferably, the micro-movement absorbing means are provided at three locations at equal intervals in the circumferential direction.

Preferably, the tap holding portion is detachably provided with respect to the float shaft.

Preferably, in order to integrally rotate the tap holder body and the float shaft, a drive pin extending through the interface between the tap holder body and the float shaft, and a drive pin provided in the tap holder body for rotating the drive pin and the tap holder body. and a pin receiving hole that defines the amount of travel.

Preferably, the float shaft includes a gripping portion having a center hole for receiving the tap holding portion, and is provided with centering gripping means for centering and gripping the tap holding portion inserted into the center hole with respect to the float shaft.

Preferably, the float shaft is provided with retaining means for preventing the tap holder from coming off the float shaft.

Preferably, the tap holder includes tap centering means for aligning the axis of the tap holder with the axis of the tap.

Preferably, the locking portion includes a guide portion that guides minute axial movement of the float shaft with respect to the tap holder body.

Preferably, the locking part is a pipe fixed to the center hole of the tap holder body and having a fluid passage for supplying coolant or air from the tap holder body side to the tap holding part side.

According to the present invention, it is possible to absorb not only errors in the axial direction but also errors in the rotational direction.

It is a side view showing a tap holder concerning an embodiment of the invention. FIG. 2 is an enlarged view of a portion of FIG. 1; 3 is a cross-sectional view taken along line III-III of FIG. 2; FIG. 3 is a cross-sectional view taken along line IV-IV of FIG. 2; FIG. It is a figure which takes out and shows a tap holder main body, (A) is sectional drawing, (B) is the top view seen from the arrow V of FIG. 5(A). 6(A) is a cross-sectional view, (B) is a plan view seen from arrow VIIb in FIG. 6(A), and (C) is VIIc in FIG. 6(A). 6(D) is a cross-sectional view taken along line VIId--VIId of FIG. 6(A); FIG. It is a figure which takes out and shows a drive pin. It is a figure which takes out and shows an elastic body. FIG. 2 is an enlarged view of a portion of FIG. 1; It is a figure which extracts and shows a tap holding|maintenance part. It is a figure which shows the modification of a tap holding|maintenance part. It is a side view which shows the modification of a tap holder.

An embodiment of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a side view showing a tap holder 1 according to an embodiment of the invention, and FIG. 2 is a partially enlarged view of FIG. In FIG. 1, substantially half of the drawing is a side view, and substantially the remaining half is a cross section. The arrow T in FIGS. 1 and 2 is referred to as the axial front end side, and the direction opposite to the arrow T is referred to as the axial rear end side. 3 is a cross-sectional view along line III-III in FIG. 2, and FIG. 4 is a cross-sectional view along line IV-IV in FIG.

1 and 2, the tap holder 1 according to the present embodiment performs tapping by synchronous control for synchronizing the rotation of the main shaft and the shaft feed using an NC device. The tap holder 1 is for mounting a tap 9 for tapping, and is attached to the spindle of a machine tool. The tap holder 1 includes a tap holder main body 2, a pipe as a locking portion 3, a float shaft 4, and a tap holding portion 6 as main components.

First, the tap holder main body 2 will be described. The tap holder main body 2 is attached to the spindle of the machine tool and positioned on the rear end side of the tap holder 1 . The tap holder body 2 has a central hole 20 extending along the axis of the tap holder 1 represented by a dashed line.

5A and 5B are views showing the tap holder main body 2 taken out, where (A) is a cross-sectional view and (B) is a plan view seen from the arrow V in FIG. 5(A). Further referring to FIG. 5 , the tap holder main body 2 includes a rear end region 21 positioned on the machine tool side and a tip region 22 positioned further to the tip side in the axial direction than the rear end region 21 . Of the center holes 20 , the center hole 20 a axially penetrating the rear end region 21 is formed to have a smaller radial dimension than the center hole 20 b axially penetrating the tip region 22 . As a result, a stepped portion 26 is provided at the boundary of the center hole 20 between the rear end region 21 and the front end region 22 .

The rear end region 21 is provided on its outer peripheral surface with a shank portion 25 that is detachably attached to the spindle of the machine tool. The tip region 22 has a cylindrical shape, for example, and is provided with two through holes 23 and 24 penetrating from the outer peripheral surface toward the center hole 20b. In addition, as shown in FIGS. 1 and 2 , a cylindrical covering portion 27 may be provided on the outer peripheral surface of the tip region 22 to cover the two through holes 23 and 24 .

As shown in FIGS. 2 and 4, of the two through holes, the first through hole 23 formed on the rear end region 21 side is a pin receiving hole through which the drive pin 7, which will be described later, passes. The cross-sectional shape of the first through hole 23 is, for example, an elliptical long hole shape, and the dimension in the axial direction is larger than the dimension in the circumferential direction. Specifically, between the first through hole 23 and the drive pin 7, axial gaps G3, G3 and rotational gaps G4, G4 are provided. The axial clearance G3 may be larger than the rotational clearance G4. The first through hole 23 and the drive pin 7 will be described later.

Of the two through holes, the second through hole 24 formed on the side of the tap holding portion 6 is an elastic body receiving hole through which the elastic body 8 described later passes. The cross-sectional shape of the second through hole 24 is circular, for example. It is preferable that the second through hole 24 and the elastic body 8 are provided in close contact with each other. The elastic body 8 will be described later.

As shown in FIG. 3, it is preferable that the first through-holes 23 and the second through-holes 24 are provided at three locations at equal intervals in the circumferential direction. Furthermore, from the viewpoint of processing, it is preferable that the first through-hole 23 and the second through-hole 24 are provided so as to overlap each other in the axial direction.

As shown in FIGS. 1 and 2 , the engaging portion 3 extending along the axis of the tap holder 1 is fixed to the center hole 20 of the tap holder body 2 . Specifically, the locking portion 3 is a pipe having a fluid passage for supplying coolant or air from the tap holder main body 2 side to the tap holding portion 6 side. The central hole 30 of the pipe 3 extends along the axis of the tap holder 1 represented by the dashed line, like the central hole 20 of the tap holder body 2 .

Although the pipe 3 of this embodiment is fixed to the tap holder body 2 by the lock bolts 35 extending in the radial direction, the tap holder body 2 and the locking portion 3 may be integrally formed. The pipe 3 is sealed by seal rings 31 and 32 attached to the center hole 20 of the tap holder body 2 . The pipe 3 is provided with an outward flange portion 33 protruding radially outward at an intermediate position in the axial direction. Between the outward flange portion 33 and the stepped portion 26 of the tap holder main body 2, an inward flange portion 45 of the float shaft 4, which will be described later, is arranged. The axial dimension of the inward flange portion 45 of the float shaft 4 is set smaller than the axial dimension between the stepped portion 26 of the tap holder body 2 and the outward flange portion 33 of the pipe 3 . Thereby, the pipe 3 defines the axial gaps G1 and G2 of the float shaft 4 . Axial gaps G1 and G2 will be described later.

The outer peripheral surface of the pipe 3 is provided with a contact surface 34 that contacts the inward flange portion 45 of the float shaft 4 on the axial rear end side of the outward flange portion 33 . The contact surface 34 functions as a guide portion that guides minute axial movement of the float shaft 4 with respect to the tap holder body 2 .

Next, the float shaft 4 will be explained. FIG. 6 is a view showing the float shaft taken out, (A) is a cross-sectional view, (B) is a plan view seen from arrow VIIb in FIG. 6 (A), and (C) is FIG. 6A) is a cross-sectional view taken along line VIIc-VIIc, and (D) is a cross-sectional view taken along line VIId-VIId of FIG. 6A. 1, 2 and 6, the float shaft 4 is attached to the tip region 22 of the tap holder body 2 and positioned on the tip side of the tap holder 1. As shown in FIG. The tap holder body 2 has a central hole 40 extending along the axis of the tap holder 1 represented by a dashed line.

The float shaft 4 includes a rear end region 41 received and held by the front end region 22 of the tap holder body 2 and a front end region 42 provided on the front end side of the rear end region 41 in the axial direction. Of the center holes 40 , a center hole 40 a that axially penetrates the rear end side of the rear end region 41 is formed to have a smaller radial dimension than a center hole 40 b that axially penetrates the tip region 42 . As a result, an inward flange portion 45 projecting radially inward is provided in a region from the rear end region 41 of the float shaft 4 to the boundary portion between the center holes 40a and 40b. Two holes 43 and 44 are provided in the rear end region 41 . These holes 43 and 44 are preferably blind holes, unlike the first and second through holes 23 and 24 formed in the tap holder body 2 .

Of the two holes, the first hole 43 formed on the tap holder body 2 side is aligned with the first through hole 23 of the tap holder body 2 in the radial direction while the float shaft 4 is held by the tap holder body 2. communicates with The first hole portion 43 is a hole to which a drive pin 7, which will be described later, is fixed. Drive pin 7 is shown in FIG. The drive pin 7 is driven into the first hole portion 43, and the lower end portion and the first hole portion 43 are pressed and fixed. Furthermore, the upper end of the drive pin 7 passes through the first through hole 23 of the tap holder body 2 . That is, the drive pin 7 extends through the interface between the tap holder body 2 and the float shaft 4 . As a result, the tap holder body 2 and the float shaft 4 rotate together.

As shown in FIG. 4, it is preferable that the dimension in the rotational direction of the first through hole 23 of the tap holder body 2 is larger than the diameter of the drive pin 7 by the gaps G4, G4. Thereby, the first through hole 23 defines the rotational direction gap between the drive pin 7 and the tap holder body 2 . Furthermore, the axial dimension of the first through hole 23 is preferably larger than the diameter of the first hole portion 43 by the gaps G3, G3. Thereby, the first through hole 23 defines the axial clearance between the drive pin 7 and the tap holder body 2 . Further, the gaps G3, G3 in the axial dimension are larger than the gaps G1, G2 described above. The gaps G1, G2, and G3 are the amount of movement of the float shaft 4 in the axial direction, and the gap G4 is the amount of movement of the float shaft 4 in the rotational direction. Since the drive pins 7 are inserted into the first through holes 23 and the first holes 43 described above, the drive pins 7 are provided at three locations at equal intervals in the circumferential direction.

As described above, the rear end region 41 of the float shaft 4 is provided with the inward flange portion 45 projecting radially inward. As shown in FIG. 2 , the inward flange portion 45 is sandwiched between the stepped portion 26 of the tap holder body 2 and the outward flange portion 33 of the pipe 3 . An axial gap G<b>1 is provided between the stepped portion 26 of the tap holder body 2 and the axial rear end portion of the rear end region 41 of the float shaft 4 . Further, an axial gap G2 is provided between the inward flange portion 45 of the float shaft 4 and the outward flange portion 33 of the pipe 3 . Axial errors can be absorbed by the axial gaps G1 and G2. Thus, the float shaft 4 is held by the tap holder body 2 with an axial clearance and a rotational clearance.

As shown in FIGS. 1, 2, and 6, the second hole portion 44 formed on the tip side in the axial direction of the two hole portions is the state in which the float shaft 4 is held by the tap holder body 2, and the above-described hole portion 44 is formed. It communicates with the second through hole 24 of the tap holder main body 2 in the radial direction. The second hole portion 44 is a hole into which the micro-movement absorbing means 8, which will be described later, is fitted. The diameter of the second through hole 24 is preferably substantially the same as the diameter of the second hole portion 44 .

The micro-movement absorbing means 8 absorbs micro-movements of the float shaft 4 with respect to the tap holder body 2 in the axial and rotational directions. Specifically, the micro-movement absorbing means 8 is an elastic body that exerts elastic force in the axial direction and the rotational direction. The elastic body 8 is preferably a cylindrical body having an axis extending in the radial direction of the tap holder body. The material of the elastic body 8 is, for example, rubber or synthetic resin.

FIG. 8 is a perspective view showing the elastic body 8 taken out. As shown in FIG. 8 , the elastic body 8 includes a main body portion 80 and a tubular hole portion 81 extending substantially in the center of the main body portion 80 . The cylindrical hole portion 81 extends in a direction orthogonal to the radial direction with respect to the center hole 40 . As shown in FIGS. 1-3, the elastic body 8 extends so as to pass through the interface between the tap holder body 2 and the float shaft 4 . That is, the elastic body 8 radially extends through the second through hole 24 of the tap holder body 2 and the second hole portion 44 of the float shaft 4 . Since the elastic bodies 8 are inserted into the second through holes 24 and the second hole portions 44 described above, the elastic bodies 8 are provided at three locations at equal intervals in the circumferential direction.

FIG. 9 is a cross-sectional view showing an enlarged centering gripping means and retaining means. As shown in FIGS. 2 and 9 , the tip region 42 of the float shaft 4 is provided with centering gripping means and retaining means for fastening and fixing the tap holding portion 6 to the float shaft 4 . The tip region 42 has a central bore 40b that receives the tap retainer 6 . The tip region 42 functions as a gripping portion that grips the tap holding portion 6 .

In particular, as shown in FIG. 6A, the grip portion 42 of the float shaft 4 includes a male screw portion 47 formed on the rear end side in the axial direction, a tapered outer surface 46 that tapers toward the tip in the axial direction, and a male A third through hole 48 is provided between the threaded portion 47 and the tapered outer surface 46 . As shown in FIG. 6C, the grasping portion 42 is provided with a slot 49 that is open on the front end side in the axial direction and closed on the rear end side in the axial direction. It is preferable that three slits 49 be provided at equal intervals in the circumferential direction. Moreover, as shown in FIG. 6D, it is preferable that three third through holes 48 are provided at equal intervals in the circumferential direction. A sphere 51 (FIG. 9) is arranged in each of the three third through holes 48 .

A clamp nut 50 is attached to the grip portion 42 of the float shaft 4 . Specifically, the clamp nut 50 is a cylindrical member, and has a female threaded portion 57 that is screwed into the male threaded portion 47 of the grip portion 42 on its inner peripheral surface, and a tapered portion that tapers toward the distal end in the axial direction. It includes a tapered inner surface 56 that abuts the tapered outer surface 46 of the portion 42, and a sphere pushing portion 58 that pushes the sphere 51 radially inward.

The centering gripping means centers and grips the tap holding portion 6 with respect to the float shaft 4 . The movement of the centering gripping means is as follows. By rotating the clamp nut 50 , the female threaded portion 57 is screwed into the male threaded portion 47 of the float shaft 4 . As a result, the width of the slot 49 in the circumferential direction becomes narrower, so that the diameter of the grip portion 42 is gradually reduced. The tap holding portion 6 is tightened by the clamp nut 50 over the entire circumference and held by the holding portion 42 . As a result, the tap holding portion 6 can be detachably held, and the tap holding portion 6 can be easily centered.

Next, the tap holder 6 will be described. FIG. 10 is a diagram showing the tap holding portion 6 taken out. The tap holder 6 shown in FIG. 10 holds the tap 9, and employs a so-called taper collet system. The tap holder 6 has a central hole 60 extending along the axis of the tap holder 1 indicated by a dashed line. A tap 9 is held in the center hole 60 . As shown in FIGS. 1, 2 and 10, the tap holder 6 is detachably attached to the tip of the float shaft 4 in the axial direction.

As shown in FIGS. 9 and 10, the tap holding portion 6 includes a mounting portion 61 inserted into the center hole 40b of the float shaft 4 and a holding portion 62 holding the tap 9. As shown in FIG. The mounting portion 61 has a recess 61a formed on its outer peripheral surface with which the spherical body 51 described above is engaged. The concave portion 61a preferably has a hemispherical cross-sectional shape. The recesses 61a may be grooves extending over the entire circumference, or recesses provided at regular intervals in the circumferential direction. As shown in FIG. 9 , the concave portion 61 a is formed at a position radially adjacent to the third through hole 48 when the tap holding portion 6 is attached to the float shaft 4 . Thereby, the ball 51 is positioned between the recess 61 a of the tap holding portion 6 and the third through hole 48 .

The retaining means prevents the tap holding part 6 from coming off from the float shaft 4. - 特許庁The movement of the retaining means is as follows. By rotating the clamp nut 50 , the female threaded portion 57 is screwed into the male threaded portion 47 of the float shaft 4 . As a result, the ball pushing portion 58 of the clamp nut 50 pushes the ball 51 toward the recess 61a, and the ball 51 and the recess 61a are engaged. As a result, the disengagement and rotation of the tap holding portion 6 are restricted.

The holding portion 62 has a holding portion main body 63, a collet 65 provided on the axial leading end side of the holding portion main body 63, and nuts 67 attached to the outer peripheral side and the axial leading end side of the holding portion main body 63 and the collet 65. . A male screw portion 64 is provided on the tip end side of the holding portion main body 63 in the axial direction. A tapered outer surface 66 that tapers toward the tip in the axial direction is provided on the tip side in the axial direction of the collet 65 . The collet 65 is provided with a plurality of slits (not shown) that are open on the axial front end side and closed on the axial rear end side. The nut 67 is a cylindrical member, and has a female threaded portion 68 screwed onto the male threaded portion 64 of the holder main body 63 on its inner peripheral surface, and a tapered outer surface 66 of the collet 65 that tapers toward the tip in the axial direction. and a tapered inner surface 69 that abuts the

The tap holder 6 includes tap centering means for making the axis of the tap holder 1 and the axis of the tap 9 coincide with each other. The movement of the tap centering means is as follows. The nut 67 is rotated to screw the female screw portion 68 into the male screw portion 64 of the holding portion main body 63 . A tapered inner surface 69 of nut 67 tapers into a tapered outer surface 66 of collet 65 . As a result, the width of the slot in the circumferential direction becomes narrower, so that the diameter of the collet 65 is gradually reduced. The tap holding part 6 is tightened by the nut 67 over the entire circumference and held by the collet 65 . Thereby, the tap 9 can be easily centered.

FIG. 11 shows a tap holding portion 6A of a modified example of FIG. 11, the shape of the mounting portion 61 of the tap holding portion 6A shown in FIG. 11 is substantially the same as that of the tap holding portion 6 shown in FIG. is different. Since the tap holder 1 of the present embodiment holds the tap holding portion 6 by the centering gripping means and the retaining means, a plurality of types of tap holding portions 6 and 6A can be selectively used. Although the taper collet method is adopted as the tap centering means for the tap 9 in the tap holding portion 6, there are various methods such as a shrink fitting method in which the tap 9 is held by utilizing thermal contraction and thermal expansion of the tap holding portion 6. may be adopted.

Next, operation|movement of the tap holder 1 which concerns on this Embodiment is demonstrated.

The tap holder 1 according to the present embodiment is attached to a main shaft and synchronizes rotation and shaft feed according to the pitch of the taps 9 . However, due to the increase in size and aging of machine tools, synchronization may be lost and the rotation of the main shaft may not follow the feed of the shaft, resulting in a slight deviation between the rotation of the main shaft and the feed of the shaft.

In the tap holder 1 of this embodiment, an axial gap G1 is provided between the tap holder main body 2 and the float shaft 4, and an axial gap G2 is provided between the float shaft 4 and the engaging portion 3. there is Therefore, it is possible to allow a minute displacement of the tap holder main body 2 in the axial direction (T) or in the opposite direction. Due to this minute displacement, the elastic body 8 is deformed in the axial direction, and the float shaft 4 can be returned to its original position in the axial direction by its elastic restoring force. As a result, the tap 9 moves slightly forward or backward to match its own pitch, so that it is possible to absorb a minute error in the axial direction and achieve synchronization.

Further, the float shaft 4 also has an error in the direction of rotation as well as an error in axial feed. In the tap holder 1 of the present embodiment, rotational direction gaps G4, G4 are provided between the first through hole 23 of the tap holder body 2 and the drive pin 7 fixed to the float shaft 4. As shown in FIG. Therefore, minute displacement in the rotational direction of the tap holder body 2 can be allowed. Due to this minute displacement, the elastic body 8 is deformed in the rotational direction, and its elastic restoring force can return the float shaft 4 to its original position in the rotational direction. As a result, the tap 9 rotates minutely so as to match its own pitch, so minute errors in the direction of rotation can be absorbed and synchronization can be achieved.

As described above, since the tap holder 1 according to the present embodiment is provided with the minute movement absorbing means between the tap holder body 2 and the float shaft 4, the axial direction of the float shaft 4 with respect to the tap holder body 2 and the It can absorb minute movements in the rotational direction and return to its original position. This enables highly accurate tapping. Further, even if the float shaft 4 is slightly displaced axially and rotationally, the elastic body 8 is compressed only until the drive pin 7 and the wall surface of the first through hole 23 contact each other. In other words, the drive pin 7 serves as a mechanical stopper that limits the rotational and axial compression of the elastic body 8 . Since the drive pin 7 restricts large elastic deformation of the elastic body 8, deterioration of the elastic body 8 can be suppressed and durability can be improved.

Furthermore, since the elastic body 8 of the present embodiment is a cylindrical body having an axis extending in the radial direction of the tap holder body 2, the amount of deformation can be increased. It is possible to reliably absorb the axial error and rotational error due to the error of the shaft feed and return it to the original position.

Further, by providing the centering gripping means, the tap centering means of the tap holding portion 6, and the guide portion 34 of the locking portion 3, the axis of the tap 9 can be aligned with the axis of the tap holder 1. It is possible to improve the run-out accuracy.

Although the tap holder 1 of the present embodiment has both the drive pin 7 and the micro-movement absorbing means (elastic body 8), the tap holder 1B shown in FIG. Only the elastic body 8) may be provided alone. Further, in the tap holder 1 of the present embodiment, the drive pin 7 and the micro-movement absorbing means (elastic body 8) are provided at different positions, but they may be provided at the same position.

Further, although the micro-movement absorbing means of this embodiment extends so as to pass through the interface between the tap holder body 2 and the float shaft 4, it does not have to extend so as to pass through their interface. , micro-movement absorbing means may be provided in the gap between the drive pin 7 and the first through hole 23 .

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within an equivalent scope.

INDUSTRIAL APPLICABILITY The present invention is advantageously used in machine tools.

REFERENCE SIGNS LIST 1 tap holder 2 tap holder main body 3 locking portion (pipe) 4 float shaft 6, 6A tap holding portion 7 drive pin 8 micro-movement absorbing means (elastic body) 9 tap 20 center hole 23 Pin receiving hole (first through hole) 34 Guide part (contact surface) 42 Tip region (gripping part) 46 Tapered outer surface 48 Third through hole 50 Clamp nut 51 Sphere 56 Tapered inner surface 61, 61A Tap holder, G1, G2, G3 axial clearance, G4 rotational clearance.

Claims (11)

A tap holder body attached to the spindle of a machine tool;
a float shaft that is held by the tap holder body with an axial clearance and a rotational clearance and that rotates integrally with the tap holder body;
a locking portion that is fixed to the tap holder body and defines the amount of movement of the float shaft in the axial direction;
a tap holder that holds a tap and is attached to the tip of the float shaft in the axial direction;
micro-movement absorbing means for absorbing micro-movements of the float shaft relative to the tap holder body in the axial and rotational directions ;
a drive pin extending through an interface between the tap holder body and the float shaft to integrally rotate the tap holder body and the float shaft;
A pin receiving hole that is provided in the tap holder body and defines the amount of movement in the rotational direction between the drive pin and the tap holder body,
The micro-movement absorbing means is provided at a position different from the drive pin and the pin receiving hole,
A tap holder, wherein a rotational clearance and an axial clearance are provided between the drive pin and the pin receiving hole . 2. The tap holder according to claim 1, wherein said micro-movement absorbing means includes an elastic body extending so as to pass through an interface between said tap holder body and said float shaft and exhibiting elastic force in the axial and rotational directions. 3. The tap holder according to claim 2, wherein said elastic body is a cylindrical body having an axis extending radially of said tap holder body. 4. The tap holder according to any one of claims 1 to 3, wherein said micro-movement absorbing means are provided at three locations at equal intervals in the circumferential direction. The tap holder according to any one of claims 1 to 4, wherein the tap holding portion is detachably provided with respect to the float shaft. the float shaft includes a gripping portion having a central hole for receiving the tap holding portion;
The tap holder according to any one of claims 1 to 5 , further comprising centering gripping means for centering and gripping the tap holding portion inserted into the center hole with respect to the float shaft. 7. The tap holder according to claim 6 , wherein said float shaft has retaining means for preventing said tap holding portion from coming off from said float shaft. The tap holder according to any one of claims 1 to 7 , wherein the tap holder includes tap centering means for making the axis of the tap holder and the axis of the tap coincide with each other. The tap holder according to any one of claims 1 to 8 , wherein the engaging portion includes a guide portion that guides minute axial movement of the float shaft with respect to the tap holder body. 10. The engaging portion is a pipe fixed to the center hole of the tap holder body and having a fluid passage for supplying coolant or air from the tap holder body side to the tap holding portion side. The tap holder described in A tap holder body attached to the spindle of a machine tool;
a float shaft that is held by the tap holder body with an axial clearance and a rotational clearance and that rotates integrally with the tap holder body;
a locking portion that is fixed to the tap holder body and defines the amount of movement of the float shaft in the axial direction;
a tap holder that holds a tap and is attached to the tip of the float shaft in the axial direction;
micro-movement absorbing means for absorbing micro-movements of the float shaft relative to the tap holder body in the axial and rotational directions;
the micro-movement absorbing means includes an elastic body that extends so as to pass through the interface between the tap holder body and the float shaft and exerts elastic force in the axial direction and the rotational direction;
The tap holder, wherein the elastic body is a cylindrical body having an axis extending in a radial direction of the tap holder main body.

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