JP5517603B2 - Retaining structure for retaining tool and retaining tool - Google Patents

Description

  The present invention relates to a holding structure for holding a tool for attaching a tool to a main shaft of a machine tool. Specifically, the shank portion is tapered by pulling a pull stud provided on an axis of the shank portion of the holding tool. The present invention relates to a holding structure for a holding tool and a holding tool that are fitted into a hole.

As a holding structure of a holding tool that has been widely known, there is one shown in Japanese Patent Laid-Open No. 2001-239406 and Patent Document 1. Hereinafter, an example of the holding structure of the holder disclosed in Patent Document 1 will be described with reference to FIG. 5 (FIG. 1 of Patent Document 1). In addition, as for the shank part 22 of FIG. 5, the pull stud 23, etc., the upper half in the figure shows a retracted state, and the lower half shows an open state.
A taper hole 7 having a corresponding tapered shape for detachably mounting the tapered shank portion 22 of the holder 20 is provided at the tip of the main shaft 5 that is rotatably supported by the housing 1 of the machine tool. Yes. Reference numeral 2 denotes a bearing.
For the rear part of the shank part 22 in the holder 20, the front part 23a of the pull stud 23 is integrally fixed in a state where it can be inserted into a deep part on the axis of the internal space 6 of the main shaft 5, Further, a bulging portion 24 is provided at the rear portion of the pull stud 23.
A tip of a draw bar 31 (shown as an example of the pulling tool 30) in the internal space 6 inside the main shaft 5 and provided for moving the ball 34 forward and backward between the open position 14 and the tightening position 15 A ball holding member 32 is integrally provided on the part side, and a ball receiving hole 33 is formed at the tip of the ball holding member 32, and the surface of the ball 34 is pulled with the inner peripheral surface of the main shaft 5. The studs 23 are stored so as to be exposed toward the outer peripheral surface of the stud 23. 8 is a pull stud insertion hole, 10 is a hole for a pulling tool, 11 is a spring accommodating hole, 37 is a spring, and 39 is a spring receiving member.
On the other hand, on the inner peripheral surface of the main shaft 5, in a state where the ball 34 is positioned at the open position 14 by the advancement of the ball holding member 32, the passage of the bulging portion 24 formed on the deep side of the pull stud 23 is not hindered. A recess 14 for retracting the ball 34 is provided so that the ball 34 can be retracted in the outer peripheral direction. Further, when the ball 34 is in the tightening position 15 due to the retraction of the ball holding member 32, the ball 34 is in the bulging portion of the pull stud 23. Engaging with the outer periphery of the engaging surface 25 of the front side slope, the shank portion 22 is also retracted together with the pull stud 23, and the outer surface of the tapered shank portion 22 in the holder on the inner surface of the tapered hole 7 on the main shaft side. A ball contact surface 17 is provided on the inner peripheral surface of the main shaft 5 so as to maintain a state in which the corresponding contact pressure is applied to 22a.
A groove (engagement groove) 28 that is open to the rear end is formed on the outer periphery of the flange portion (鍔) 21 a around the main body portion 21 in FIG. 5, and the groove 28 is attached to the front end surface 5 a of the main shaft 5. A non-illustrated piece (also referred to as a driving piece) is detachably inserted to prevent the rotation of both.
Although not shown, a holding portion for holding the tool is formed on the front surface 21b of the flange portion (鍔) 21a as is well known, and the tool is held by the holding portion.

JP 2001-239406 A

In this conventional holder holding structure,
A pull stud 23 having a bulging portion 24 is provided at the rear axial position of the shank portion 22 in the holder 20, and a plurality of balls are engaged from the periphery with respect to the outer periphery of the engaging surface of the bulging portion 24 at the axial position. In addition to the internal structure of the main shaft 5, the structure of the rear portion of the shank portion 22 of the holder 20 is simplified, and in addition, the axial position of the shank portion 22 is unevenly distributed. There is an effect that can be drawn in a good balance.
However, the anti-rotation of the shank portion 22 in the state where the tapered shank portion 22 of the holder 20 is attached to the tapered hole 7 provided in the tip portion of the main shaft 5 is the outer periphery of the flange portion (鍔) 21a. An unillustrated piece (also referred to as a drive piece) attached to the front end surface 5a of the main shaft 5 is detachably inserted into the groove (engagement groove) 28 provided in FIG. Therefore, the engagement state of both has a dimensional allowance (play) in the rotation direction in order to facilitate the attachment / detachment operation, and the accuracy of the follow-up operation of the holder 20 is inferior to the rotation operation of the main shaft 5. There was a problem.

An object of the present application is to provide a holding structure for a holder that can simplify the internal structure of the main shaft and the configuration of the shank portion of the holder.
Another object of the present invention is to provide a holding structure and a holding tool of the holding tool with high accuracy in which the follow-up operation of the holding tool becomes faithful to the turning operation of the main shaft.
Other objects and advantages will be readily apparent from the drawings and the following description associated therewith.

The holding tool holding structure according to the present invention is a means for detachably attaching the tapered shank portion 22 of the holding tool 20 to the tip of the main shaft 5 that is rotatably supported by the housing 1 of the machine tool. A tapered hole 7 having a tapered shape is provided,
For the rear part of the shank part 22 in the holder 20, the tip part 23a of the pull stud 23 is integrally fixed to a deep part on the axis line of the internal space 6 of the main shaft 5 so as to be insertable. Further, a bulging portion 24 is provided at the rear portion of the pull stud 23, and
In the inner space 6 inside the main shaft 5, a ball holding member 32 is integrally formed on the front side of the draw bar 31 provided for moving the ball 34 forward and backward between the open position 14 and the tightening position 15. The ball holding holes 32 are respectively formed at the front portions of the ball holding members 32, and the surfaces of the balls 34 are exposed to the inner peripheral surface of the main shaft 5 and the outer peripheral surface of the pull stud 23, respectively. In the state,
On the other hand, on the inner peripheral surface of the main shaft 5, in a state where the ball 34 is positioned at the open position 14 by the advancement of the ball holding member 32, the passage of the bulging portion 24 formed on the deep side of the pull stud 23 is not hindered. A recess 14 for retracting the ball 34 is provided so that the ball 34 can be retracted in the outer peripheral direction. Further, when the ball 34 is in the tightening position 15 due to the retraction of the ball holding member 32, the ball 34 is in the bulging portion of the pull stud 23. Engaging with the outer periphery of the engaging surface 27 of the front side slope, the shank portion 22 is also retracted together with the pull stud 23, and the outer surface of the tapered shank portion 22 in the holder is formed on the inner surface of the tapered hole 7 on the main shaft side. In the holding structure of the holder in which the ball contact surface 17 is provided on the inner peripheral surface of the main shaft 5 so that the state in which 22a is in contact can be maintained.
The shape of the ball contact surface 17 provided on the inner peripheral surface of the main shaft 5 is formed in a long concave groove shape parallel to the axial direction of the main shaft 5, and the ball contact surface formed in the concave groove shape. 17 cross-sectional shape, the movement of the ball 34 along the longitudinal direction of the ball abutment surface 17 but allows, is the ball 34 moves in the circumferential direction of the main shaft 5 is formed in a concave curved surface that is not allowed Yes,
The shape of the engaging surface 27 of the front side slope in the bulging portion 24 of the pull stud 23 is formed in a long concave groove shape toward the deep side , and the gradient of the groove bottom surface is pulled toward the deep side. The cross-sectional shape of the engaging surface 27 formed in the above-described concave groove shape is inclined so as to be far from the axis of the stud 23, and the ball 34 is relative to the longitudinal direction of the engaging surface 27. movement is allowed, that the ball 34 moves in the circumferential direction of the bulging portion of the pull stud 23 is made by forming a concave curved surface which is not allowed.

Preferably, the rear portion of the main body of the holder 20 includes a tapered shank portion 22, and the front portion of the pull stud 23 is attached to the rear portion of the shank portion 22.
It is fixed integrally to a deep part on the inner space axis of the main shaft 5 so that it can be inserted,
Furthermore, the rear portion of the pull stud 23 is a holding tool having a bulging portion 24,
The configuration of the spindle 5 of the machine tool for mounting the shank portion 22 in the holder is rotatably supported by a frame, and the tapered shank portion 22 in the holder is attached to and detached from the tip of the spindle 5. It has a tapered hole 7 with a corresponding tapered shape for free mounting,
In the inner space inside the main shaft 5, a ball holding member 32 is integrally formed on the front side of the draw bar 31 provided for moving the ball 34 forward and backward between the open position 14 and the tightening position 15. The ball holding member 32 is formed with a ball receiving hole 33 at the front portion thereof, and the surface of the ball is exposed to the inner peripheral surface of the main shaft 5 and the outer peripheral surface of the pull stud 23, respectively. In
On the other hand, on the inner peripheral surface of the main shaft 5, in the state in which the ball reaches the open position by the advancement of the ball holding member 32, the outer peripheral direction is prevented without obstructing the passage of the bulging portion formed on the deep side of the pull stud 23. A recess 14 for retracting the ball is provided so that it can be retracted.
In a state where the ball is in the tightening position by the retraction of the ball holding member 32, the ball engages with the outer periphery of the engaging surface 27 of the front side slope at the bulging portion of the pull stud 23, and the pull stud 23 is pulled in. At the same time, the shank portion 22 is also retracted, and a ball contact surface 17 is provided on the inner peripheral surface of the main shaft 5 so that the outer surface of the tapered shank portion 22 in the holder can be kept in contact with the inner surface of the tapered hole on the main shaft side. And
The shape of the ball contact surface 17 provided on the inner peripheral surface of the main shaft 5 is formed in a long concave groove shape parallel to the axial direction of the main shaft 5, and the ball contact surface formed in the concave groove shape. 17 cross-sectional shape, the movement of the ball along the longitudinal direction of the ball abutment surface 17 but allows, is the ball is moved in the circumferential direction of the main shaft 5 is each other to form the concave curved surface is not allowed ,
The shape of the engagement surface 27 of the front side slope in the bulging portion 24 of the pull stud 23 in the holder 20 is formed in a concave groove shape that is long toward the deep side , and the gradient of the groove bottom surface is on the deep side. The slope is far from the axis of the pull stud 23 toward the
The cross-sectional shape of the engaging surface 27 formed in the above-described concave groove shape is
While the ball 34 allows relative movement along the longitudinal direction of the engagement surface 27 ,
That the ball 34 moves in the circumferential direction of the bulging portion of the pull stud 23 is made by forming a concave curved surface which is not allowed.

   As described above, the present invention includes the pull stud 23 including the bulging portion 24 on the rear axis of the shank portion 22 of the holder 20, and the outer periphery of the engaging surface of the bulging portion 24 in the axial position is Since the configuration is such that a plurality of balls are engaged and pulled in from the periphery, the configuration of the rear portion of the shank portion 22 in the holder 20 is simplified, and the axial position of the shank portion 22 is drawn in a balanced manner without being unevenly distributed. There is an effect that can.

  In addition, in the present invention, the shape of the ball contact surface provided on the inner peripheral surface of the main shaft 5 is formed in a long groove shape parallel to the axial direction of the main shaft 5, and the cross-sectional shape of the groove 17. The ball 34 is formed in a curved fitting groove that allows the ball 34 to move along the longitudinal direction of the concave groove 17 but does not allow the ball 34 to move in the circumferential direction of the main shaft 5. The shape of the engaging surface 27 of the front side slope in the bulging portion 24 of the 23 is formed in a long concave groove shape with a gradient that increases the diameter on the deep side, and the cross section of the concave groove 27 The shape of the curved engagement groove 27 is such that the ball 34 is allowed to move relative to the longitudinal direction of the concave groove 27 but the ball 34 is not allowed to move in the circumferential direction of the bulging portion of the pull stud 23. Because it is formed, even if its configuration is simple, it can be understood from FIG. As described above, only by retracting the ball 34 in the direction of the arrow 44 by the ball holding member 32, the bulging portion 24 of the pull stud 23 can be retracted, and the inner surface of the main shaft 5 is applied to the ball 34. The concave groove at the front side becomes the fitting groove 17, the engaging surface of the front side slope in the bulging portion 24 of the pull stud 23 becomes the meshing groove 27, and the three members are meshed and fixed in the circumferential direction. Two effects are produced simultaneously, that is, a strict integral rotation in the circumferential direction of the shank portion 22 with respect to the rotation of the shank, and an improvement in accuracy related to the rotation.

FIG. 3 is a longitudinal sectional view for explaining the relationship between a main shaft, a holding tool, and a pulling tool, in which (A) shows an unclamped state and (B) shows a clamped state. 1 is a sectional view taken along line IIA-IIA, FIG. 1B is a sectional view taken along line IIB-IIB, FIG. 1C is a sectional view taken along line IIC-IIC, and FIG. FIG. 11 is a cross-sectional view taken along the line IIC-IIC, excluding the ball. In the sectional view for explaining the relationship between the fitting groove provided on the inner peripheral surface of the main shaft, the engagement groove provided on the outer peripheral surface of the bulging portion of the pull stud of the holder, and the ball in the pulling tool, The enlarged view of the III arrow position of FIG. 1 (B). FIG. 4 is a view for explaining the positional relationship between the engagement groove provided on the outer peripheral surface of the bulging portion of the pull stud of the holder and the ball, (A) is a partial cross-sectional view, and (B) is a partial front view. Sectional drawing around the spindle of a machine tool for explaining a conventional example.

  Embodiments of the present invention will be described below with reference to the drawings. In the above-mentioned background art section, FIG. 5 is used as an illustration for explaining the technical matters described in Patent Document 1. In the following description, the configuration (means), the functions, properties, and features of the members, etc. that are given the same reference numerals as those used in FIG. 5 are the new member configurations and combinations added in the following description. Except for matters relating to the explanation, etc., since it is known from Japanese Patent Application Laid-Open No. 2003-260260 and is common technical knowledge, this point will be explained briefly.

  In the drawing, reference numeral 1 denotes a housing of a machine tool, and a taper-shaped shank portion 22 of a holder 20 is detachably mounted on a tip portion of a main shaft 5 that is rotatably supported by the housing. A tapered hole 7 having a corresponding tapered shape is provided. The slope of the tapered hole 7 is arbitrary, but as is known from JIS, in Japan, 7/24, 1/10 taper, etc. are often used. 2 indicates a bearing. In the internal space (hollow part) 6 of the main shaft, 8 is a hole for inserting a pull stud, 10 is a hole for accommodating the pulling tool 30, and 11 is a hole for accommodating the spring 37.

  On the inner peripheral surface of the hollow portion 6 of the main shaft 5, a large-diameter retracting recess 14 is provided around. In the state in which the pulling ball 34 is located at the open position 14 by the advancement of the ball holding member 32, the retracting recess 14 is formed in the deep portion of the pull stud 23 as shown in FIGS. The dimension corresponding to the size of the ball 34 (large diameter) so that the ball 34 can be retracted in the outer peripheral direction so as not to prevent the bulging portion 24 formed on the side from being pulled out (passed) to the right side in the figure. A recess 14 for evacuation is provided.

Further, the ball tightening position (small diameter portion) 15 on the inner peripheral surface of the main shaft 5 is in contact with the retracting recess 14 as shown in FIGS. Attached surface 17 is provided. The shape of the ball contact surface 17 provided on the inner peripheral surface of the main shaft 5 is formed in a long concave groove shape parallel to the axial direction of the main shaft 5, and the cross-sectional shape of the concave groove 17 is that the ball 34 is a concave groove. Although the movement along the longitudinal direction of 17 is allowed, the curved surface of the ball 34 is not allowed to move in the circumferential direction of the main shaft 5. Since the curved surface serves as a fitting groove, for example, it is formed into a curved surface corresponding to the curved surface of the ball 34 or a curved U-shape (V-shape) slightly smaller than the curved surface on the outer periphery of the ball 34. You just have to.
The number of the concave grooves 17 is equally provided at three locations on the inner peripheral surface of the main shaft 5 as is apparent from FIG. Note that the number of the concave grooves 17 may be plural, that is, two or more such as two places and four places arranged in the circumferential direction.
16 indicates the presence of an introduction slope. The introduction slope is a funnel-like slope for guiding the balls 34 from the recesses 14 for retraction to the grooves 17 as the fitting grooves to the grooves 17 respectively. Due to the presence of this, even if the position of the ball 34 is slightly shifted in the rotational direction with respect to the inner surface of the main shaft 5, the ball 34 can be properly guided and introduced into each concave groove 17.

A front part 23a (also referred to as a front part) of the pull stud 23 is integrally fixed to the rear part of the shank part 22 at the rear part of the main part 21 in the holder 20 as shown in FIG. . As the fixing means, as is well known, the two may be screwed together so as to be integrally rotatable, or may be formed of an integral material. Further, the shank portion 22 may be hollow or solid. In the state of FIG. 1, the pull stud 23 can be inserted into the deep portion of the axial position of the internal space 6 of the main shaft 5. Further, a bulging portion 24 is provided at the rear portion of the pull stud 23 as is well known. In the figure, 21a, 21b, 22a, 25 are each a well-known saddle part, a part for holding a tool (not shown), a taper part having a slope corresponding to the taper hole 7, and other well-known machine tools. The front side slope which made the slope so that the ball | bowl of the arbitrary magnitude | sizes in this pulling tool can be engaged is shown.

In the inner space 6 inside the main shaft 5, a draw bar 31 for advancing and retracting the ball 34 between the open position 14 and the tightening position 15 is provided as a pulling tool 30 as is widely known. .
As is well known, a drawbar advance / retreat mechanism (not shown) is connected to the rear part of the drawbar 31, and a part of the drawbar 31 is configured on the front side of the drawbar 31 (may be integrated with the drawbar 31). A ball holding member 32 is integrally provided with a member 31a interposed. Although the ball holding member 32 is often formed in a cup shape, there is a type in which a plurality of arms corresponding to the number of balls protrude from the front side of the draw bar 31. A plurality (three in total in FIG. 2) of ball receiving holes 33 are formed at the tip of the ball holding member 32, and the surface of the ball 34 is formed on the main shaft 5, as can be understood from the drawings. The inner peripheral surface 17 and the outer peripheral surface 27 of the pull stud 23 are accommodated so as to be exposed to each other.

The shape of the engaging surface 27 of the front side slope in the bulging portion 24 of the pull stud 23 is such that the bulging portion is pressed so strongly toward the deep portion that the ball 34 of the ball receiving hole 33 advances and retreats. It is formed in a concave groove shape having a long gradient with a gradient that expands (protrudes) toward the deep side of 24 (in many cases, approximately 30 degrees as understood from θ1 in FIG. 4A). is there.
The sectional shape of the concave groove 27 allows the ball 34 to move relative to the longitudinal direction of the concave groove 27, but allows the ball 34 to move in the circumferential direction of the bulging portion of the pull stud 23. It is formed into a curved surface that is not formed, and is a curved surface that constitutes a meshing state.
Since the curved surface serves as the engagement groove 27, for example, a curved surface corresponding to the curved surface of the ball 34 or a curved U-shape (V-shaped) slightly smaller than the curved surface on the outer periphery of the ball 34 is formed. You just have to.
26 indicates the presence of the introduction groove. The introduction groove 26 is a funnel-shaped slope for guiding the surface of the ball 34 on the pull stud side from the position of the recess 14 for retraction toward the concave groove 27 as the meshing groove to each meshing groove 27. When this exists, the ball 34 can be properly guided and introduced into the meshing grooves 27 even if the position of the ball 34 is slightly shifted in the rotational direction with respect to the peripheral surface of the pull stud 23. it can.
The number of the engaging grooves 27 which are the ball contact surfaces corresponds to the engaging grooves 17 and is equally provided at three places around the bulging portion 24 as is apparent from FIG. is there. In addition, the number of the engagement grooves 27 may be a plurality, that is, two or more such as two places, four places, etc., which are equally arranged in the circumferential direction.
In addition, 37 in the spring accommodating hole 11 pulls in the ball 34 as shown in FIG. 1B, and maintains the state in which the fitting groove 17 and the engagement groove 27 are locked in the rotation direction via the ball 34. A spring for energizing in the direction of arrow 44 is shown, and generally a disc spring or a winding spring as shown in the figure is used. 38 is a step (spring receiver) provided on the draw bar 31 side, and 39 is a spring receiving member provided on the main shaft 5 side. In the unclamped state of FIG. 1A, the spring 37 is compressed by the draw bar 31 as is well known, and in the clamped state, the draw bar 31 is retracted by a mechanism not shown in the well known manner. Reference numeral 43 denotes an arrow in the forward direction (unclamping direction), and 44 denotes an arrow in the backward (retraction) / (clamp) direction.

The use state of the above configuration will be described. After removing another holding tool using "ATC" in the previous process,
The main shaft 5 and the pulling tool 30 are in the state shown in FIG. On the other hand, the holder 20 is mounted using “ATC” as shown in the figure. The attachment means is arbitrary, but “ATC” may be used as is well known.
Next, the draw bar 31 is loosened, and the ball 34 is pulled into the position shown in FIG. In the retraction process, one surface of the ball 34 is introduced into the fitting groove 17, and the other surface is introduced into the inclined surface of the engaging groove 27 (an inclined surface of about 30 degrees in FIG. 4A). While moving along with the ball 34, the ball 34 is directed to the deep part, and the state shown in FIGS. 1B and 3 is obtained.
Accordingly, when the ball 34 is in the tightening position 15 in FIG. 1B due to the retraction of the ball holding member 32, the ball 34 constitutes a part of the front side slope 25 in the bulging portion 24 of the pull stud 23. As shown in FIG. 4 (A), it engages with an engagement surface 27 that is an inner circumferential surface of the meshing groove 27 in an inclined state in which the rear portion that expands has a diameter.
On the other hand, the other surface of the ball 34 stays in the middle of the deep fitting groove 17 as shown in FIG.

1 ... Housing,
2 ... Bearing
5 ... Spindle,
6 ... Internal space (hollow part),
7: Tapered hole,
8 ... Pull stud insertion hole,
10 ... Hole for pulling tool,
11 ... Spring accommodating hole,
14 ... Ball opening position (large diameter part),
15: Ball tightening position (small diameter part),
16 ... Introductory slope,
17 ... concave groove (fitting groove),
20 ... retainer,
21 ... Main part,
21a ・ ・ ・ 鍔,
21b ・ ・ ・ Tool holder,
22 ... Shank part,
22a ・ ・ ・ Tapered part,
23 ... Pull stud,
24 ... bulge part,
25 ... front side slope for engagement,
26 ... introduction groove,
27 ... concave groove (meshing groove),
30 ...
31 ... Drawbar,
32 ... Ball holding member,
33: Ball receiving hole,
34 ... ball,
37 ... spring,
38 ... Step (spring receiver),
39 ... Spring receiving member,
θ1 ... Angle of the meshing slope 27,
43 ... Forward direction (unclamp) arrow,
44 ... Retraction (retraction) (clamp) direction arrow.

Claims (2)

The tip of the main shaft that is rotatably supported by the housing of the machine tool is provided with a tapered hole with a corresponding tapered shape for detachably mounting a tapered shank portion in the holder,
With respect to the rear part of the shank part in the holder, the front part of the pull stud is integrally fixed to the deep part on the axis of the inner space of the main shaft so as to be insertable, and further to the rear part of the pull stud. Has a bulge,
A ball holding member is integrally provided on the front side of the draw bar in the internal space inside the main shaft and provided to advance and retract the ball between the open position and the tightening position. Each ball receiving hole is formed in the tip of each, and the surface of the ball is stored in a state of being exposed to the inner peripheral surface of the main shaft and the outer peripheral surface of the pull stud,
On the other hand, on the inner peripheral surface of the main shaft, the ball can be retracted in the outer peripheral direction without obstructing the passage of the bulging portion formed on the deep side of the pull stud when the ball is positioned at the open position by the advancement of the ball holding member. Provided with a recess for retracting the ball,
In a state where the ball is in the tightening position by the retraction of the ball holding member, the ball engages with the outer periphery of the engaging surface of the front side slope in the bulging portion of the pull stud, and the shank portion is pulled together with the pull stud retracting. The holding structure of the holder is provided with a ball contact surface on the inner peripheral surface of the main shaft so that the outer surface of the tapered shank portion of the holder can be kept in contact with the inner surface of the taper hole on the main shaft side. In
The shape of the ball contact surface provided on the inner peripheral surface of the main shaft is formed in a long groove shape parallel to the axial direction of the main shaft, and the cross-sectional shape of the ball contact surface formed in the groove shape , the movement of the ball along the longitudinal direction of the ball abutment surface but allows, is the ball is moved in the circumferential direction of the main shaft is Yes formed concavely curved unacceptable,
The shape of the engaging surface of the front side slope in the bulging portion of the pull stud is formed in a concave groove shape that is long toward the deep side , and the gradient of the bottom surface of the groove is the axis of the pull stud toward the deep side. and each other in the gradient as the distance from the cross-sectional shape of the engagement surface is formed on the groove shape, but the ball is allowed relative movement along the longitudinal direction of the engagement surface, said holding structure of the holder the balls are moved in the circumferential direction of the bulging portion of the pull stud, characterized in that formed in the concave curved surface is not allowed.
The rear part of the main body of the holder is provided with a tapered shank part, and the front part of the pull stud is attached to the rear part of the shank part.
It is fixed to the deep part on the inner space axis of the main shaft so that it can be inserted integrally.
Furthermore, the rear part of the pull stud is a holder provided with a bulging part,
The configuration of the spindle of the machine tool for mounting the shank portion in the holder is rotatably supported by a frame, and the tapered shank portion of the holder is detachably attached to the tip of the spindle. It has a tapered hole with a corresponding tapered shape for
In the inner space inside the main shaft, a ball holding member is integrally provided on the front side of the draw bar provided for moving the ball forward and backward between the open position and the tightening position, thereby holding the ball. A ball receiving hole is formed in each tip of the member, and the surface of the ball is stored in a state where the surface is exposed toward the inner peripheral surface of the main shaft and the outer peripheral surface of the pull stud,
On the other hand, on the inner peripheral surface of the main shaft, the ball can be retracted in the outer peripheral direction without hindering the passage of the bulging portion formed on the deep side of the pull stud when the ball reaches the open position by the advancement of the ball holding member. Provided with a recess for retracting the ball,
In a state where the ball is in the tightening position by the retraction of the ball holding member, the ball engages with the outer periphery of the engaging surface of the front side slope in the bulging portion of the pull stud, and the shank portion is pulled together with the pull stud retracting. In addition, a ball contact surface is provided on the inner peripheral surface of the main shaft so that the outer surface of the tapered shank portion of the holder can be in contact with the inner surface of the taper hole on the main shaft side.
The shape of the ball contact surface provided on the inner peripheral surface of the main shaft is formed in a long groove shape parallel to the axial direction of the main shaft, and the cross-sectional shape of the ball contact surface formed in the groove shape , the movement of the ball along the longitudinal direction of the ball abutment surface but allows, is the ball is moved in the circumferential direction of the main shaft are each other to form a concave curved surface that is not permitted,
The shape of the engagement surface of the front side slope at the bulging part of the pull stud in the holder is formed in a long concave groove shape toward the deep side , and the gradient of the groove bottom surface is pulled toward the deep side. The slope is far from the stud axis ,
The cross-sectional shape of the engagement surface formed in the above-mentioned concave groove shape is
The ball allows relative movement along the longitudinal direction of the engagement surface ,
Holder, characterized in that the said ball is moved in the circumferential direction of the bulging portion of the pull stud is formed in a concave curved surface which is not allowed.

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