JP2000246522A - Chuck, bar stock holding device and automatic lathe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a bar stock from being oscillated when the bar stock is rotated, and thereby enhance the processing accuracy of the bar stock to a great extent by enhancing the bar stock holding function of a chuck itself. SOLUTION: A chuck 10 is provided with a first and a second slotting part 14 and 16 to be provided for the front and rear ends in the axial direction of a cylindrical main body 12. In the first slotting part 14, the application of pressure to the tapered surface of each outer circumference of respective main body portions divided so as to be formed up by three slits 18, thereby allows the bar stock holding surface 24 of an inner circumference to be contracted in diameter so as to let the bar stock be fixedly held. The second slotting part 16 is provided with an inner cylindrical member 30 to be mounted to the rear end area of the cylindrical main body 12, and pressure is applied to a male screw part 38 over each outer circumference of respective main body portions 28 inwardly in the radial direction by the main body portions 28 and inner cylindrical portions 24, which are divided so as to be formed up by respective three pieces of slits 26 and 32. This constitution thereby causes an elastic deflection permitting the bar stock to be held by the bar stock holding surface 40 of the inner circumference of the inner cylindrical member 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar gripping chuck which can be mounted on a machine tool such as a lathe and a bar gripping device provided with the chuck. Further, the present invention relates to an automatic lathe provided with such a bar gripping device.

[0002]

2. Description of the Related Art In a machine tool such as an NC lathe capable of performing automatic turning (collectively referred to as an automatic lathe in this specification), a bar-shaped material (bar material) to be machined is detachably attached to a rotating spindle. A bar comprising a chuck having a hollow cylindrical main body formed with an elastically deformable gripping portion, and an operating mechanism for elastically deforming the gripping portion of the chuck to cause the gripping portion to firmly grip the bar. Devices incorporating a device are known. The chuck is usually installed concentrically at the inner tip of a hollow rotating spindle. The operating mechanism includes a hollow sleeve member that is concentrically housed in the main shaft and is movable in the axial direction, and a driving device that moves the sleeve member in the main shaft in the axial direction.

Conventionally, in this type of bar gripping device, a plurality of (normally three) slits are provided at one end in the axial direction of the chuck as a gripping portion, and a slit is formed. In general, the bar is gripped by operating to apply a pressure inward in the radial direction to the outer peripheral surface of the rod to reduce the diameter of the slit. In this case, a tapered surface for receiving pressure is formed on the outer peripheral surface of the slit portion of the chuck.

[0004] On the other hand, the operating mechanism employs either a configuration in which the sleeve member is fixedly connected to the chuck or a configuration in which the sleeve member moves relative to the chuck. In the former configuration, a tapered working surface capable of engaging with a tapered surface on the outer periphery of the slit portion is formed at a tip end portion of the spindle surrounding the chuck, and when gripping the bar, the sleeve member is attached to the spindle along with the chuck. The gripping pressure is obtained by pressing the tapered surface against the working surface by displacing the tapered surface inward. Further, in the latter configuration, the sleeve member surrounds the chuck, and a tapered working surface that can be engaged with the tapered surface on the outer periphery of the slit is formed at the tip portion thereof. By displacing the member with respect to the chuck in the tip direction of the spindle and pressing the working surface against the tapered surface,
Get the gripping pressure.

[0005]

In the above-mentioned automatic lathe provided with the conventional bar gripping device, when a large number of products are continuously formed by turning from a long bar, the bar is rotated from the rear end to the rotating spindle. The bar is inserted and supplied to the chuck, and the bar is processed by sequentially projecting the required length of the bar from the chuck. At this time, it is known that during the turning operation of the front end processed portion of the bar material gripped by the chuck, deflection occurs in the rear unprocessed portion of the high-speed rotating bar material due to the inherent bending of the bar material. Have been. In addition, as a factor that further increases the run-out, since the bar material generally has an uneven outer diameter in the length direction, the grip portion having the slit structure has a local annular area on the inner peripheral surface thereof (usually a chuck). The mechanical structural factor that the bar can be gripped only in the tip region) can be cited.

[0006] As a characteristic of the above-mentioned run-out that occurs during turning of a bar, it is known that an unprocessed portion behind the chuck causes rotation like a standing wave (also referred to as a skipping phenomenon) in a rotating spindle. When such a phenomenon occurs, the processed end portion of the bar protruding from the chuck vibrates, and the processing accuracy (dimensional accuracy, concentricity, cylindricity, surface roughness, etc.) is deteriorated. Therefore, conventionally, measures are taken to eliminate the deflection of the bar by providing a bar anti-sway device rotatably supporting the bar supplied to the rotary spindle behind the rotary spindle. However, depending on the processing accuracy required for the product, such a bar steadying device may be excessively installed. In addition, the arrangement of the bar steadying device is not only an addition of a mechanical mechanism, but also in an automatic machining system using an NC lathe or the like, a control mechanism for the bar steadying device is required. There is a fear that equipment costs will rise.

By the way, the chuck generally holds the bar material inserted from its rear end with the grip portion at the front end, so that a portion other than the grip portion has an inner diameter larger than the outer diameter of the bar material to be processed. You. The gripping portion of the chuck has an inner diameter slightly larger than the outer diameter of the bar to be machined in a no-load state, and grips the bar in a local annular area on its inner peripheral surface when the diameter is reduced. At this time, in order to reduce the deflection of the bar, it is conceivable to reduce the inner diameter of the portion other than the gripping portion of the chuck, but in that case, it becomes difficult to insert the bar into the chuck. The inner diameter can be reduced only to the extent. Therefore, it is difficult to sufficiently suppress the deflection of the bar with such a configuration.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a chuck for holding a bar, which can be mounted on a machine tool such as a lathe, by suppressing the deflection of the bar during rotation by improving the bar holding function of the chuck itself. Accordingly, it is an object of the present invention to provide a chuck capable of significantly improving the processing accuracy of a bar. Another object of the present invention is to provide a bar gripping device that can be mounted on a machine tool such as a lathe, provided with a high-performance chuck capable of suppressing run-out during rotation of the bar, and a bar capable of avoiding an increase in equipment cost of the machine tool. An object of the present invention is to provide a material holding device.
Still another object of the present invention is to provide an automatic lathe provided with such a bar gripping device and capable of preventing the structure of the automatic machining system from becoming complicated.

[0009]

In order to achieve the above object, the invention according to the first aspect has an elastically deformable grip provided on a cylindrical main body, and the bar can be released from the grip. A chuck that can be gripped at a plurality of positions, wherein the gripping portions are provided at a plurality of locations spaced apart in the axial direction of the tubular main body. According to a second aspect of the present invention, in the chuck according to the first aspect, the grip portion is provided at a first slit provided at one axial end of the cylindrical main body, and at a second axial end of the cylindrical main body. And a second slit which is provided.

According to a third aspect of the present invention, there is provided the chuck according to the second aspect, wherein each of the first and second slits has a tapered surface formed along an outer peripheral surface thereof. According to a fourth aspect of the present invention, there is provided the chuck according to the third aspect, wherein one of the first and second slit portions has a tapered surface formed by a male screw.

The invention according to claim 5 is the invention according to claim 3 or 4.
2. The chuck according to claim 1, wherein an inner cylindrical member having a corresponding slit is mounted on one inner peripheral surface of the first and second slits. According to a sixth aspect of the present invention, there is provided the chuck according to any one of the first to fifth aspects, and an operating mechanism configured to elastically deform the gripping portion of the chuck to cause the gripping portion to releasably grip the bar. The present invention provides a bar gripping device.

According to a seventh aspect of the present invention, there is provided the bar gripping device according to the sixth aspect, wherein the operating mechanism elastically deforms a plurality of gripping portions of the chuck by operations related to each other. . The invention according to claim 8 is the invention according to claim 6.
Or the rod holding device according to 7, wherein the operating mechanism comprises a sleeve member concentrically arranged on the chuck and movable in the axial direction, and a driving device for moving the sleeve member in the axial direction. provide.

According to a ninth aspect of the present invention, there is provided a bar gripper provided with the chuck according to the third aspect, and an operating mechanism for elastically deforming the gripper of the chuck to cause the gripper to releasably grip the bar. In the apparatus, an actuating mechanism detachably engages with the respective tapered surfaces of the first and second slit portions of the chuck and presses the tapered surfaces when engaged. The present invention provides a bar gripping device characterized by having a second working surface.

According to a tenth aspect of the present invention, there is provided a bar gripper provided with the chuck according to the fourth aspect, and an operating mechanism for elastically deforming the gripper of the chuck to cause the gripper to releasably grip the bar. In the apparatus, an operating mechanism engages with an axially movable female screw that is screwed to a male screw that constitutes one tapered surface of the chuck, and detachably engages with the other tapered surface of the chuck, and forms the tapered surface when engaged. A bar gripping device comprising: a pressing surface; An eleventh aspect of the present invention is the invention according to any one of the sixth to tenth aspects.
The present invention provides an automatic lathe characterized in that the bar gripping device described in the above item is incorporated in a rotating spindle.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the drawings, the same or similar components are denoted by common reference numerals. Referring to FIGS. 1 and 2, a chuck 10 according to a first embodiment of the present invention is shown in cross-sectional and end views, respectively. The chuck 10 fixedly holds a bar (not shown), and can be mounted on a main shaft of a machine tool such as an automatic lathe. The chuck 10 includes a hollow cylindrical main body 12 capable of receiving a rod therein, and elastically deformable gripping parts 14 provided at a plurality of positions spaced apart in the axial direction of the cylindrical main body 12.
16. These grip portions 14 and 16 are provided with a first slit 14 provided at the front end in the axial direction of the cylindrical main body 12.
And a second slit 16 provided at the rear end in the axial direction of the cylindrical main body 12.

The first slit portion 14 has three slits 18 formed in the axial direction from the front end face 12a of the cylindrical main body 12 over a predetermined length, thereby forming the main body divided into three parts. Each of the portions 20 is adapted to be able to elastically flex radially. A tapered surface 22 is formed on the outer peripheral surface of each body portion 20 of the first slit portion 14. Further, the inner peripheral surfaces of the main body portions 20 of the first slit portion 14 cooperate with each other to act as a cylindrical bar gripping surface 24. Therefore, the first slit portion 14 applies a radially inward pressure to each tapered surface 22 so that each body portion 20 elastically bends, the bar gripping surface 24 is reduced in diameter, and the chuck 10 is closed. In this state, the bar is fixedly held. When the radial pressure on the first slit 14 is released, each body portion 20 is elastically restored and the bar gripping surface 2
4, the chuck 10 is opened to release the bar.

The second slit 16 has three slits 26 formed in the axial direction from the rear end face 12b of the cylindrical main body 12 over a predetermined length, thereby forming the main body divided into three parts. Each of the portions 28 is adapted to be able to elastically flex radially. Rear end surface 12b of cylindrical body 12
An inner cylindrical member 30 having a corresponding slit is attached to an inner peripheral surface area adjacent to the inner cylindrical member 30. That is, the inner cylindrical member 30
Is provided with three slits 32 at positions corresponding to each of the three slits 26 of the cylindrical main body 12, whereby each of the three divided inner cylinder portions 34 is elastically bent in the radial direction. Is available. The inner cylindrical member 30 is fixed to the inner peripheral surface of the cylindrical main body 12 by, for example, an adhesive at a base end portion 36 having no slit 32, while each inner cylindrical portion 34 is formed on the outer peripheral surface of the cylindrical main body 12. It slidably contacts the inner peripheral surface. The axial end face 30 a of the inner cylinder member 30 on the side of the slit 32 is disposed on substantially the same plane as the rear end face 12 b of the tubular main body 12.

On the outer peripheral surface of each main body portion 28 of the second slit portion 16, there is provided a male screw portion 38 which works in cooperation with each other. Also, the inner cylindrical member 30 attached to the cylindrical main body 12
The inner peripheral surfaces of the respective inner cylindrical portions 34 cooperate with each other to act as cylindrical bar gripping surfaces 40. Accordingly, the second slit 16 applies a radially inward pressure to each of the male threaded portions 38 so that each of the main body portions 28 and each of the inner cylindrical portions 34 are formed.
Is bent to reduce the diameter of the bar gripping surface 40 and grip the bar. When the radial pressure on the second slit 16 is released, the main body portions 28 and the inner cylinder portions 34 are restored, and the bar gripping surface 40 is expanded, thereby releasing the bar.

As shown in FIG. 3, in the chuck 10, an annular concave portion 4 extending in the circumferential direction along the outer peripheral surface is provided in a connection area between each inner cylindrical portion 34 and the base end portion 36 of the inner cylindrical member 30.
2 is preferably formed. The annular concave portion 42 has an effect of reducing the thickness of the inner cylindrical member 30 at that portion and improving the flexibility of each inner cylindrical portion 34 with respect to the base end portion 36. Further, it is desirable that the outer peripheral surface 34a of each inner cylindrical portion 34 extends in a tapered shape from the axial end surface 30a toward the annular concave portion 42 as shown in the figure. According to such a configuration, the contact area between each main body portion 28 and each inner cylinder portion 34 in the second slit portion 16 is reduced, so that it occurs when the second slit portion 16 is elastically deformed. Each body part 28
There is an advantage that the friction force between the inner cylinder portion 34 and the inner cylinder portion 34 is reduced.

According to the chuck 10 having the above configuration,
Since the first and second slit portions 14 and 16 are provided at the front end and the rear end in the axial direction of the cylindrical main body 12, respectively, the slits 14 and 16 are locally annular in the bar gripping surfaces 24 and 40. Even if the bar is gripped only in the region, the bar is gripped by the chuck 10 at two locations separated in the axial direction. Therefore, for example, in an automatic lathe, when the chuck 10 grips a long bar and turns the tip of the bar, when the bar is essentially bent or has an uneven outer diameter. However, due to the excellent bar gripping function of the chuck 10 itself, it is possible to minimize the deflection of the rear unprocessed portion of the high-speed rotating bar.

In the chuck 10, an inner cylindrical member 30 is provided at the rear end in the axial direction of the cylindrical main body 12, and
The bar material holding surface 40 having an inner diameter smaller than the inner diameter of the rod material is formed. In this case, when the pressure is not applied to the second slit portion 16,
Any size may be used as long as it does not make it difficult to insert the bar into the inside. Nevertheless, according to chuck 10,
Since the bar holding surface 40 can be elastically reduced in diameter to an inner diameter as close as possible to the outer diameter of the bar, the deflection of the bar can be sufficiently suppressed, and the processing accuracy (dimensional accuracy, concentricity, Cylindricity, surface roughness, etc.) can be significantly improved.
At this time, the first slit portion 14 needs a gripping pressure capable of firmly fixing and gripping the bar, but the second slit portion 16 needs to be strong enough to firmly fix the bar. At least, it is sufficient that a gripping pressure that can sufficiently suppress the deflection of the bar is obtained.

As a method of manufacturing the chuck 10, the following two methods can be proposed. In the first method, the slit 1
In a predetermined region of the front end and the rear end of the cylindrical main body 12 in which the 8, 8 are not formed, three slits 18,
26 is engraved. In a separate step, a predetermined area at the rear end of the inner cylindrical member 30 where the slit 32 is not formed
The slits 32 are engraved. Next, while aligning the slits 26 and 32, the inner cylinder member 30 is fixed to the rear end portion of the cylindrical body 12 using an adhesive or the like as described above. In the second method, first, the inner cylindrical member 30 having no slit 32 is fixed to the rear end portion of the cylindrical main body 12 not having the slits 18 and 26 using an adhesive or the like as described above. . Next, three slits 18 are cut in a predetermined region of the front end of the cylindrical main body 12 by machining to form a first slit.
A slit 14 is formed. Further, a cutting blade is collectively inserted into a predetermined region at the rear end of the cylindrical main body 12 and the inner cylindrical member 30, and three slits 26 and 32 are carved to form the second slit 16. In either method, the first
Using a conventional chuck with only a slot,
The chuck 10 can be manufactured by forming the second slit 16 in a later step.

FIG. 4 shows a bar gripping device 50 according to a first embodiment of the present invention having the chuck 10 incorporated in a rotary spindle 52 of an automatic lathe. FIG. 4 is an enlarged cross-sectional view of a main part of the bar holding device 50. The rotating spindle 52 is
It is rotatably accommodated in the headstock 56 via the bearing device 54, and is rotationally driven by a drive source (not shown) in a state where the bar to be processed is firmly gripped. The rotating main shaft 52 has a hollow cylindrical structure, and an elongated bar is fed into the inside from the rear end.

The bar gripping device 50 includes a chuck 10 installed concentrically in the inner tip region of the rotating main shaft 52 and first and second slit portions 14 and 16 of the chuck 10 which are elastically deformed and slid. An operating mechanism 58 is provided for causing the split portions 14 and 16 to releasably grip the bar. Actuation mechanism 58
A sleeve member 60 concentrically housed in the rotating main shaft 52 so as to be slidable in the axial direction;
And a driving device 62 for moving the inside in the axial direction. The driving device 62 can adopt a known configuration in a conventional general chuck operating mechanism, and thus the description is omitted.

The sleeve member 60 is a hollow cylindrical body capable of receiving a rod material, and has a female screw portion 64 which can be screwed to each of the male screw portions 38 of the chuck 10 in the front end region of the inner surface thereof.
The chuck 10 and the sleeve member 60 are fixedly connected to each other via a male thread 38 and a female thread 64. Therefore, the chuck 10 is displaced in the axial direction along with the sleeve member 60 when the sleeve member 60 of the operation mechanism 58 moves in the axial direction in the main shaft 52. It should be noted that such a connection structure using a screw portion is generally and conveniently employed to facilitate replacement of the chuck 10. Supplementally, the easily replaceable chuck 10 is provided with a groove 44 (FIG. 1) extending from substantially the center in the axial direction of the cylindrical main body 12 to the rear end surface 12b at a predetermined angular position on the outer peripheral surface of the cylindrical main body 12. The groove 44 receives a detent 66 that fixes the chuck 10 to the rotating main shaft 52 in the rotation direction when the chuck 10 is mounted on the rotating main shaft 52.

A tapered working surface 68 which can be engaged with each tapered surface 22 of the first slit portion 14 of the chuck 10 is formed in a tip region of the rotary spindle 52 surrounding the chuck 10. Therefore, as the chuck 10 is displaced in the direction (axially rearward) drawn into the main shaft 52 by the operating mechanism 58, each tapered surface 2 of the first slit portion 14 is displaced.
2 is pressed against the working surface 68 of the rotating spindle 52. As a result, a radially inward pressure is applied to each tapered surface 22 to reduce the diameter of the bar gripping surface 24, and the first slit portion 14 is closed. Also, when the chuck 10 is displaced from the closed state by the operating mechanism 58 in the direction in which the chuck 10 is pushed out from the main shaft 52 (forward in the axial direction), each tapered surface 22 of the first slit portion 14 becomes an operating surface 68 of the rotary main shaft 52. Detached from As a result, the radial pressure on the first slit portion 14 is released, and the bar gripping surface 24 expands in diameter.
Is opened.

In the bar gripping device 50, the operating mechanism 5
8, the first and second slit portions 14 of the chuck 10,
The bars can be firmly gripped by the chuck 10 by elastically deforming the members 16 in an operation related to each other as follows, that is, a series of operations of the sleeve member 60. First, the chuck 10 is set to the open state, a long bar is inserted into the inside of the rotary spindle 52 from the rear end thereof, and supplied to the chuck 10 through the sleeve member 60. And
With the required processing length of the bar protruding from the chuck 10, the operating mechanism 58 is started, and the chuck 10 is displaced in the direction of being pulled into the main shaft 52 integrally with the sleeve member 60. Thereby, first, the bar gripping surface 24 of the first slit portion 14 is reduced in diameter as described above, and the bar is gripped firmly.

When each tapered surface 22 of the first slit portion 14 of the chuck 10 engages with the operating surface 68 of the rotary spindle 52, the axial movement of the chuck 10 stops. In this state, the operation mechanism 58 continues to operate, and the sleeve member 60
Is further displaced in a direction of being drawn into the main shaft 52. Then, as shown in FIG. 5, the female screw portion 64 of the sleeve member 60 is formed.
Is strongly pressed against the threaded screw surface 72 of each male screw portion 38 of the second slit 16 of the chuck 10. Due to the contact surface pressure P at this time, a radially inward pressure is applied to the screw surface 72 of each of the male screw portions 38, and each of the inner cylindrical portions 34 of the inner cylindrical member 30 bends to reduce the diameter of the bar gripping surface 40. Then, the second slit 16 is closed (arrow Q). In this way, following the first slot 14, the bar gripping surface 40 of the second slot 16 grips the bar.

When the second slit 16 is in the closed state, the operating mechanism 58 is operated to move the sleeve member 60 to the chuck 1.
0 is moved from the main shaft 52 in the pushing direction. Then, the contact surface pressure applied by the thread surface 70 of the female thread portion 64 of the sleeve member 60 to the thread surface 72 of each male thread portion 38 of the second slit 16 disappears. Thereby, the second slot 1
The radial pressure on 6 is released, the bar gripping surface 40 expands, and the second slit 16 is opened. Subsequently or substantially at the same time, the first slit 14 is opened as described above, and the bar is released from the chuck 10.

As described above, in the bar holding device 50, the male screw portion 38 of the chuck 10 and the female screw portion 6 of the sleeve member 60 are provided.
The second slit portion 16 of the chuck 10 is elastically deformed by utilizing the pressure of the contact surface with the chuck 4. Therefore, it is important that the male screw portion 38 and the female screw portion 64 have a screw structure having at least a tapered screw surface such as a trapezoidal screw or a triangular screw. Further, according to such a configuration, by a series of axial movements of the sleeve member 60, the bar is first firmly fixed and gripped by the first slit 14, and then the second slit 16 is moved by the second slit 16. The bar can be gripped by a gripping pressure that can sufficiently suppress the deflection of the bar. Here, the additional axial movement of the sleeve member 60 to apply gripping pressure to the second slit 16 also acts to increase the bar gripping pressure at the first slit 14. In lathes, it is an essential requirement to carry out high-precision machining that the bar is firmly gripped as close as possible to the turning part.
The bar holding device 50 satisfies such requirements.

According to the bar gripping device 50 having the above-described structure, the high-performance chuck 10 capable of suppressing the runout of the bar during rotation is provided. Processing with high accuracy (dimensional accuracy, concentricity, cylindricity, surface roughness, etc.) becomes possible. Therefore, in an automatic lathe in which the bar gripping device 50 is built in the rotary spindle 52, an increase in equipment costs is avoided, and the structure of the automatic machining system is not complicated.

Further, in the bar holding device 50, the operating mechanism 5
8 is a series of operations of the sleeve member 60, and the chuck 1
Since the first and second slit portions 14 and 16 are continuously elastically deformed, the structure of the operating mechanism 58 is extremely simple. In particular, the second slit 16 of the chuck 10 uses the contact surface pressure between the external thread 38 and the internal thread 64 of the sleeve member 60, which is employed to facilitate replacement of the chuck 10, by using a rod. Since the configuration is such that the material gripping pressure is obtained, there is an advantage that the operating mechanism 58 can be used without modifying the conventionally used configuration.

FIGS. 6 and 7 show a chuck 80 according to a second embodiment of the present invention. The chuck 80 is formed by forming the second slit portion 82 into an integral structure by eliminating the inner cylindrical member 30 in the chuck 10 described above. Since the chuck 80 has substantially the same configuration as the chuck 10 except for the configuration of the second slit portion 82, the same or similar components are denoted by the same reference numerals and description thereof is omitted.

The second slit 82 of the chuck 80
The cylindrical body 12 is provided with three slits 84 engraved from the rear end face 12b in the axial direction over a predetermined length, whereby each of the three divided body portions 86 is elastically bent in the radial direction. Can be used. On the outer peripheral surface of each main body portion 86 of the second slit portion 82, a male screw portion 88 acting in cooperation with each other is provided. In addition, cylindrical main body 1
2 is a region adjacent to the rear end surface 12b, the inner diameter of which is smaller than that of the central region, whereby the second slit portion 8 is formed.
A cylindrical bar gripping surface 90 cooperating with each other is formed on the inner peripheral surface of each of the two main body portions 86. Therefore, the second slit portion 82 applies a radially inward pressure to each male screw portion 88, whereby each main body portion 86 bends and the bar gripping surface 90 is reduced in diameter, thereby gripping the bar. Second slit 82
When the radial pressure is released, the main body portions 86 are restored, and the bar gripping surface 90 expands to release the bar.

The bar gripping surface 90 of the second slit 82 of the chuck 80 is such that it is not difficult to insert the rod into the chuck 80 when no pressure is applied to the second slit 82. What is necessary is just to have the inside diameter dimension of. Further, in the chuck 80, each male screw portion 8 of the second slit portion 82
It is preferable to form an annular concave portion 92 extending in the circumferential direction along the outer peripheral surface between the central portion 8 and the central region of the cylindrical main body 12. The annular concave portion 92 has an effect of reducing the thickness of the cylindrical main body 12 at that portion and improving the flexibility of each main body portion 86.

The operation and effect equivalent to those of the chuck 10 are also obtained by the chuck 80 having the above configuration. That is, due to the excellent bar gripping function of the chuck 80 itself, it is possible to minimize the deflection of the rear unprocessed portion of the bar that rotates at a high speed. Moreover, since the chuck 80 does not require the inner cylindrical member 30, the number of parts and the number of manufacturing steps can be reduced. The chuck 80 is provided with the above-described operation mechanism 58.
The bar holding device 50 can be configured in combination with the above.
In that case, the processing accuracy of the bar by the automatic lathe can be significantly improved.

FIGS. 8 and 9 show a chuck 100 according to a third embodiment of the present invention. In the chuck 100, the second slit portion 102 is formed as an integral structure, excluding the inner cylindrical member 30 in the chuck 10 described above. Since the chuck 100 has substantially the same configuration as the chuck 10 except for the configuration of the second slit 102, the same or similar components are denoted by the same reference numerals and description thereof is omitted.

The second slit 102 of the chuck 100
Is provided with three slits 104 engraved over a predetermined length in the axial direction from the rear end face 12b of the cylindrical main body 12, whereby each of the three divided main body parts 106 is elastically deformed in the radial direction. It can be deflected. Second
On the outer peripheral surface of each body portion 106 of the slit portion 102,
A tapered surface 108 extending adjacent to the rear end surface 12b is provided. Further, the inner diameter of the cylindrical main body 12 is smaller than that of the central area in the area adjacent to the rear end face 12b, so that the inner peripheral faces of the main body portions 106 of the second slit 102 cooperate with each other. A cylindrical bar gripping surface 110 is formed. Accordingly, the second slit 102 applies a radially inward pressure to each tapered surface 108,
Each body portion 106 is bent, and the bar gripping surface 110 is reduced in diameter,
Hold the bar. When the radial pressure on the second slit 102 is released, each main body portion 106 is restored, the bar gripping surface 110 is expanded, and the bar is released.

As described above, the second slit 102 of the chuck 100 is formed by the tapered surface 22 of the first slit 14.
It has a configuration in which a gripping pressure is obtained by a tapered surface 108 that is inclined in substantially the same direction as in FIG. The bar gripping surface 110 of the second slit 102 of the chuck 100 is in contact with the second slit 102.
When the pressure is not applied to the chuck 100, the inner diameter may be such that the insertion of the bar into the chuck 100 is not difficult. In the chuck 100, a shoulder surface 112 extending substantially parallel to the front end surface 12 a is formed between each tapered surface 22 of the first slit portion 14 and the front end surface 12 a of the tubular main body 12.

The operation and effect equivalent to those of the chuck 10 are also obtained by the chuck 100 having the above configuration. That is, due to the excellent bar gripping function of the chuck 100 itself,
It is possible to minimize the run-out of the rear unprocessed portion of the high-speed rotating bar. Moreover, in the chuck 100,
Since the inner cylinder member 30 is unnecessary, the number of parts and the number of manufacturing steps can be reduced. Note that, in the chuck 100, FIG.
As in the case of the chuck 10 shown in FIGS. 3 to 3, the second slit portion 102 can be formed by assembling an inner cylinder member on the rear end side of the cylindrical main body 12. In addition, the cylindrical body 12
An annular recess similar to the annular recess 92 in the chuck 80 of FIG. 6 can be formed at a desired position on the outer peripheral surface of the chuck 80.

The above-described chuck 100 is combined with an operating mechanism having a configuration different from that of the above-described operating mechanism 58 to be used in FIG.
Can be configured. FIG. 10 shows a second embodiment of the bar gripping device 120 according to the present invention equipped with the chuck 100 by using a rotary spindle 1 of an automatic lathe.
22 is shown in a state of being built in. The rotary spindle 122 is installed on a headstock (not shown) of an automatic lathe like the rotary spindle 52 shown in FIG. 4, and is rotationally driven by a drive source (not shown) while firmly holding a bar to be processed. Is done. The rotating main shaft 122 has a hollow cylindrical structure, and an elongated rod is fed from the rear end to the inside.

The bar gripping device 120 includes a chuck 100 installed concentrically in the inner tip region of the rotary spindle 122,
First and second slit portions 14, 10 of chuck 100
An actuating mechanism 124 that elastically deforms 2 and allows the slit portions 14 and 102 to releasably grip the bar.
The operating mechanism 124 includes a sleeve member 126 concentrically accommodated in the rotating main shaft 122 so as to be slidable in the axial direction, and a driving device 128 for moving the sleeve member 126 in the main shaft 122 in the axial direction. The driving device 128
Since a known configuration of a conventional general chuck operating mechanism can be employed, description thereof will be omitted.

The sleeve member 126 is a hollow cylindrical body capable of receiving a bar, and can accommodate the chuck 100 in the front end region of the inner surface thereof so as to be slidable in the axial direction. In a region near the front end of the inner surface of the sleeve member 126, a first tapered first shape which can be engaged with each tapered surface 22 of the first slit portion 14 of the chuck 100 is provided.
A working surface 130 is formed. Also, a tapered second working surface 132 engageable with each tapered surface 108 of the second slit 102 of the chuck 100 is provided on an inner surface region of the sleeve member 126 which is separated from the first working surface 130 by a predetermined distance. Is formed. The distance between the first working surface 130 and the second working surface 132 of the sleeve member 126 is such that the first and second working surfaces 130 and 132 are
08 is set to a size that allows simultaneous contact.

Between the rear end surface 12b of the chuck 100 and the sleeve member 126, the direction in which the chuck 100 is pushed out of the sleeve member 126, that is, each tapered surface 22, 10
A compression spring 134 is provided, which urges 8 away from the first and second working surfaces 130, 132. On the other hand, a cap 136 having a locking surface 138 capable of engaging with each shoulder surface 112 of the chuck 100 is detachably attached to the tip of the rotating main shaft 122. Cap 136 is attached to rotating spindle 122
Of the chuck 10
0, and retains the chuck 100 so that the chuck 100 does not fall off the sleeve member 126. In this state, the chuck 100 includes the sleeve member 126 and the cap 1
36, and is fixedly supported under the bias of a compression spring 134. When replacing the chuck 100, the cap 136 is removed from the rotating spindle 122 and the chuck 10 is removed.
0 may be extracted from the sleeve member 126.

In the bar gripping device 120, the operating mechanism 124 causes the first and second slit portions 14, 102 of the chuck 100 to perform operations related to each other as follows, ie, a series of operations of the sleeve member 126. By elastically deforming the material, the bar can be firmly gripped by the chuck 100. First, the chuck 100 is set in an open state, a long bar is inserted into the rotary spindle 122 from the rear end thereof, and supplied to the chuck 100 through the sleeve member 126. Then, with the required processing length of the bar protruding from the chuck 100, the operating mechanism 124 is started, and the sleeve member 126 is moved in the direction of being pushed out from the rotary main shaft 122 (axially forward). At this time, chuck 1
00 is locked by the cap 136 in the axial forward movement within the main shaft 122, so that the sleeve member 1 is attached to each tapered surface 22 of the first slit portion 14 of the chuck 100.
The first working surface 130 of the sleeve member 126 is pressed against the first working surface 130 of the second slit portion 102 of the chuck 100 at the same time.

In this manner, a pressure is applied radially inward to each tapered surface 22 of the first slit portion 14 of the chuck 100 to reduce the diameter of the bar gripping surface 24,
A radially inward pressure is applied to each tapered surface 108 of the slit portion 102 to reduce the diameter of the bar gripping surface 110, and as a result, the first and second slit portions 14, 102 are simultaneously closed. State. As a result, the bar material is
And the bar gripping surface 24 of the second slit portions 14, 102;
It is gripped by 110.

When the sleeve member 126 of the actuating mechanism 124 is moved from the closed state in a direction in which the sleeve member 126 is drawn into the rotary main shaft 122 (axially rearward), the chuck 100 is pressed against the cap 136 under the bias of the compression spring 134. In this state, the first and second working surfaces 130 and 132 of the sleeve member 126 are respectively connected to the respective tapered surfaces 22 and 1 of the first and second slit portions 14 and 102 of the chuck 100.
08 at the same time. As a result, the radial pressure on the first and second slit portions 14 and 102 is released, and the bar gripping surfaces 24 and 110 expand in diameter, and the first and second slit portions 14 and 102 are simultaneously In the opened state, the bar is released from the chuck 100.

As described above, in the bar holding device 120, the first and second slit portions 14 and 102 can be closed simultaneously to hold the bar by a series of axial movements of the sleeve member 126. Here, as described above, in a lathe, it is an essential requirement to perform high-precision machining by firmly gripping the bar as close as possible to the turning portion. In order for the bar gripping device 120 to satisfy such requirements, the axially forward movement of the sleeve member 126 must be the second until the first slot 14 firmly fixes and grips the bar. It is necessary to configure so as not to be hindered by engagement with the slit portion 102. For this purpose, when the first slit portion 14 firmly fixes and holds the bar, the second slit portion 102 does not firmly fix the bar, and the deflection of the bar is sufficiently suppressed. It is important to adjust the amount of bending of the first and second slit portions 14 and 102, the inner diameter of the bar gripping surfaces 24 and 110 when there is no load, and the like so as to grip the bar as much as possible. .

According to the bar holding device 120 having the above-described configuration, the bar 100 is provided with the high-performance chuck 100 capable of suppressing the run-out of the bar during rotation. High precision (dimensional accuracy, concentricity, cylindricity,
Surface roughness). Therefore, in an automatic lathe in which the bar gripping device 120 is built in the rotary spindle 122, an increase in equipment cost is avoided, and the structure of the automatic machining system is not complicated. Further, in the bar gripping device 120, the operating mechanism 124 includes the sleeve member 1
Since the first and second slit portions 14 and 102 of the chuck 100 are simultaneously elastically deformed by the series of operations 26, the configuration of the operating mechanism 124 is extremely simple.

[0050]

As is apparent from the above description, according to the present invention, the bar gripping function of the chuck itself, which can be mounted on a machine tool such as a lathe, is improved, and the bar which may be generated during the bar processing is improved. Rotational runout can be suppressed as much as possible. Accordingly, if the machine tool is equipped with the chuck of the present invention,
The processing accuracy of the bar can be significantly improved. In addition, the bar holding device equipped with a high-performance chuck capable of suppressing the deflection of the bar during rotation enables the bar to be processed with high accuracy without the need to provide a bar steadying device.
It is possible to avoid soaring equipment costs for machine tools. Further, the automatic lathe provided with such a bar gripping device can not only significantly improve the processing accuracy of the bar, but also can prevent the structure of the automatic processing system from becoming complicated.

[Brief description of the drawings]

FIG. 1 is a sectional view of a chuck according to a first embodiment of the present invention.

FIG. 2 is an end view of the chuck of FIG. 1 as viewed from the direction of arrow II.

FIG. 3 is a partially enlarged sectional view of the chuck of FIG. 1;

FIG. 4 is a cross-sectional view showing the bar holding device according to the first embodiment of the present invention mounted on a rotating spindle of an automatic lathe.

FIG. 5 is a partially enlarged sectional view of the bar gripping device of FIG. 4;

FIG. 6 is a sectional view of a chuck according to a second embodiment of the present invention.

FIG. 7 is an end view of the chuck in FIG. 6 as seen from the direction of arrow VII.

FIG. 8 is a sectional view of a chuck according to a third embodiment of the present invention.

FIG. 9 is an end view of the chuck of FIG. 8 as seen from the direction of arrow IX.

FIG. 10 is a cross-sectional view showing a state in which the bar holding device according to the second embodiment of the present invention is mounted on a rotating spindle of an automatic lathe.

[Description of Signs] 10, 80, 100: chuck 12: tubular body 14: first slot 16, 82, 102: second slot 18, 26, 32, 84, 104 slit 22, 108: tapered surface 24, 40, 90, 110: bar holding surface 30: inner cylindrical member 38, 88: male screw portion 50, 120: bar holding device 52, 122: rotary spindle 58, 124: operating mechanism 60, 126 ... Sleeve members 62,128 ... Drive device 64 ... Female screw part 68 ... Working surface 70,72 ... Screw surface 130 ... First working surface 132 ... Second working surface

Claims (11)

[Claims] 1. A chuck having an elastically deformable grip provided on a cylindrical body and capable of releasably gripping a bar in the grip, wherein the grip is separated in an axial direction of the cylindrical body. A chuck provided at a plurality of locations. 2. The grip section comprises a first slit provided at one axial end of the cylindrical main body and a second slit provided at the other axial end of the cylindrical main body. The chuck according to claim 1. 3. The chuck according to claim 2, wherein a tapered surface is formed along an outer peripheral surface of each of the first and second slits. 4. The chuck according to claim 3, wherein the tapered surface of one of the first and second slits is a threaded surface of a male screw. 5. The chuck according to claim 3, wherein an inner cylindrical member having a corresponding slit is attached to one inner peripheral surface of the first and second slits. 6. A chuck according to claim 1, further comprising: an operating mechanism for elastically deforming the grip portion of the chuck to cause the grip portion to releasably grip a bar. A bar gripping device characterized by the above-mentioned. 7. The bar holding device according to claim 6, wherein the operating mechanism elastically deforms the plurality of holding portions of the chuck by operations related to each other. 8. The apparatus according to claim 6, wherein the actuating mechanism comprises a sleeve member concentrically arranged on the chuck and movable in the axial direction, and a driving device for moving the sleeve member in the axial direction. Bar holding device. 9. A bar holding device, comprising: the chuck according to claim 3; and an operating mechanism that elastically deforms the holding portion of the chuck to cause the holding portion to releasably hold the bar. An actuating mechanism removably engages with the respective tapered surfaces of the first and second slit portions of the chuck, and presses the tapered surfaces when engaged. A bar gripping device comprising: a second working surface. 10. A bar holding device comprising: the chuck according to claim 4; and an operating mechanism that elastically deforms the holding portion of the chuck to cause the holding portion to releasably hold the bar. An actuating mechanism, an axially movable female screw threadedly engaged with the male screw forming the one tapered surface of the chuck, and detachably engaged with the other tapered surface of the chuck; A bar gripping device comprising: an operating surface for pressing a tapered surface. 11. An automatic lathe wherein the bar gripping device according to claim 6 is incorporated in a rotating spindle.