JP2008213142A - Chuck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remarkably improve the machining accuracy of a bar material by suppressing the run-out of the bar material in turning by improving the bar material gripping function of a chuck itself. <P>SOLUTION: The chuck 10 comprises a first slit portion 14 and a second slit portion 16 provided on the front and rear ends of a cylindrical body 12 in the axial direction respectively. The first slit portion 14 fixedly grips the bar material by contracting the diameter of the bar material gripping surfaces 24 formed on the inner circumference of the cylindrical body 12 by applying radially inward pressure on the respective tapered surfaces 22 provided on the outer circumferences of respective body portions 20 divided by three slits 18. The second slit portion 16 comprises an inner cylindrical member 30 to be attached to the rear region of the cylindrical body 12. Body portions 28 and inner cylindrical portions 34 divided by respective three slits 26, 32 elastically deform by applying radially inward pressure on the male screw portions 38 provided on the outer circumference of the respective body portions 28. As a result, the bar material is gripped by the bar material gripping surfaces 40 provided on the inner circumference of the inner cylindrical member 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bar gripping chuck that can be installed in a machine tool such as a lathe and a bar gripping apparatus including the chuck. The present invention further relates to an automatic lathe provided with such a bar gripping device.

  In a machine tool (generally referred to as an automatic lathe in this specification) capable of performing automatic turning such as an NC lathe, a hollow cylinder is used to detachably attach a rod-shaped material (bar material) to be processed to a rotating spindle. Incorporating a bar gripping device with a chuck that has an elastically deformable gripping part on the main body, and an operating mechanism that elastically deforms the gripping part of the chuck and firmly grips the bar to the gripping part It has been known. The chuck is usually installed concentrically at the inner tip of a hollow rotating spindle. The actuating mechanism includes an axially movable hollow sleeve member accommodated concentrically within the main shaft, and a drive device that moves the sleeve member in the axial direction within the main shaft.

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

  On the other hand, the operation 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 that can be engaged with the tapered surface on the outer periphery of the slit portion is formed at the tip of the main shaft that surrounds the chuck. When gripping a bar, the sleeve member is attached to the main shaft together with the chuck. Gripping pressure is obtained by displacing the taper surface against the action surface by displacing it in the inward direction. In the latter configuration, the sleeve member surrounds the chuck and a tapered working surface that can be engaged with the tapered surface of the outer periphery of the slit portion is formed at the tip portion of the sleeve member. A gripping pressure is obtained by displacing the member with respect to the chuck toward the tip of the spindle and pressing the working surface against the tapered surface.

  In an automatic lathe equipped with the conventional bar material gripping device described above, when a large number of products are turned continuously from a long bar material, the bar material is inserted into the main spindle from the rear end and supplied to the chuck. Then, processing is performed by sequentially protruding the required processing length portion of the bar from the chuck. At this time, it is known that during the turning operation of the tip processed portion of the bar gripped by the chuck, the deflection of the bar inherently causes a deflection in the rear unmachined portion of the bar rotating at a high speed. It has been. In addition, as a factor that further increases the deflection, since the bar generally has a non-uniform outer diameter in the length direction, the gripping portion having the slit structure has a local annular region (usually a chuck) A mechanical structural factor that the bar can be gripped only in the tip region) can be cited.

  As a feature of the above-described deflection that occurs during turning on a bar, it is known that an unmachined portion behind the chuck causes a rotation like a standing wave (also referred to as a jump rope phenomenon) within the main spindle. When such a phenomenon occurs, the tip machining portion of the bar protruding from the chuck vibrates and the machining accuracy (dimensional accuracy, concentricity, cylindricity, surface roughness, etc.) deteriorates. Therefore, conventionally, a measure has been taken to eliminate the deflection of the bar by providing a bar steadying device that rotatably supports the bar supplied to the rotation main shaft behind the rotation main shaft. However, depending on the processing accuracy required for the product, such a bar steadying device may be an excessive facility. In addition to the addition of a mechanical mechanism, the installation of a bar steadying device also requires a control mechanism for the bar steadying device in an automatic machining system such as an NC lathe. There is a risk that equipment costs will rise.

  By the way, in general, in order for the chuck to hold the bar inserted from the rear end thereof with the holding portion at the front end, an inner diameter larger than the outer diameter of the bar to be processed is given to the portion excluding the holding portion. The grip portion of the chuck has an inner diameter slightly larger than the outer diameter of the rod to be processed in an unloaded state, and grips the rod in a local annular region on the inner peripheral surface when the diameter is reduced. At this time, in order to reduce the deflection of the bar, it is possible to reduce the inner diameter of the portion other than the grip portion of the chuck, but in that case, it is not difficult to insert the bar into the chuck. The inner diameter can only be reduced to a certain extent. Therefore, it is difficult to sufficiently suppress the deflection of the bar with such a configuration.

An object of the present invention is to improve the bar gripping function of the chuck itself in a bar gripping chuck that can be equipped on a machine tool such as a lathe, thereby suppressing the deflection during rotation of the bar. It is another object of the present invention to provide a chuck that can remarkably improve the processing accuracy of a bar.
Another object of the present invention is a bar gripping device that can be mounted on a machine tool such as a lathe, provided with a high-performance chuck that can suppress deflection during rotation of the bar, and a bar that can avoid an increase in the equipment cost of the machine tool. The object is to provide a material gripping device.
Still another object of the present invention is to provide an automatic lathe that includes such a bar gripping device and can prevent the structure of an automatic machining system from becoming complicated.

In order to achieve the above object, the invention according to claim 1 is a chuck having an elastically deformable gripping portion provided in a cylindrical main body and capable of releasably gripping a bar material in the gripping portion. Provided is a chuck characterized in that the chuck is provided at a plurality of locations separated in the axial direction of the cylindrical main body.
According to a second aspect of the present invention, in the chuck according to the first aspect, the gripping portion is provided at the first slit portion provided at one axial end of the cylindrical main body and at the other axial end of the cylindrical main body. A chuck comprising a second slit portion is provided.

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

According to a fifth aspect of the present invention, in the chuck according to the third or fourth aspect, an inner cylinder member having a corresponding slit portion is attached to one inner peripheral surface of the first and second slit portions. Provide a chuck.
A sixth aspect of the present invention includes the chuck according to any one of the first to fifth aspects, and an operating mechanism that elastically deforms the gripping portion of the chuck and causes the gripping portion to releasably hold the bar. A bar material gripping device is provided.

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 the plurality of gripping portions of the chuck by operations related to each other.
According to an eighth aspect of the present invention, in the bar holding apparatus according to the sixth or seventh aspect, the operating mechanism is arranged concentrically with the chuck and is movable in the axial direction, and the sleeve member is moved in the axial direction. Provided is a bar gripping device including a driving device to be moved.

  The invention described in claim 9 is a bar gripping device comprising the chuck according to claim 3 and an operation mechanism that elastically deforms the gripping portion of the chuck and causes the gripping portion to grip the bar releasably. First and second actions that are movable in the axial direction in which the operating mechanism is detachably engaged with the respective tapered surfaces of the first and second slit portions of the chuck and presses the tapered surfaces when engaged. Provided is a bar gripping device comprising a surface.

The invention described in claim 10 is a bar holding device comprising: the chuck according to claim 4; and an operating mechanism that elastically deforms the gripping portion of the chuck and causes the gripping portion to releasably hold the bar. The actuating mechanism is an axially movable female screw that engages with the male screw constituting one tapered surface of the chuck, and an action that removably engages the other tapered surface of the chuck and presses the tapered surface during engagement. A bar material gripping device comprising a surface is provided.
The invention according to claim 11 provides an automatic lathe characterized in that the bar gripping device according to any one of claims 6 to 10 is incorporated in a rotary main shaft.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to improve the rod holding | grip function of the chuck | zipper itself which can be equipped in machine tools, such as a lathe, and to suppress the rotational runout of the bar | rod which may arise during bar | burr processing as much as possible. . Therefore, if the machine tool is equipped with the chuck of the present invention, the processing accuracy of the bar can be remarkably improved.
In addition, the bar gripping device equipped with a high-performance chuck that can suppress the deflection of the bar during rotation enables the bar to be processed with high accuracy without providing a bar steadying device. Increase in machine tool costs can be avoided.
Furthermore, an automatic lathe equipped with such a bar gripping device can not only significantly improve the bar processing accuracy but also prevent the structure of the automatic processing system from becoming complicated.

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 a cross-sectional view and an end view, respectively. The chuck 10 holds a bar (not shown) in a fixed manner, and can be mounted on a spindle of a machine tool such as an automatic lathe. The chuck 10 includes a hollow cylindrical main body 12 that can receive a rod member therein, and elastically deformable gripping portions 14 and 16 that are provided at a plurality of locations spaced in the axial direction of the cylindrical main body 12. The gripping portions 14 and 16 include a first slit portion 14 provided at the front end in the axial direction of the cylindrical main body 12 and a second slit portion 16 provided at the rear end in the axial direction of the cylindrical main body 12. .

  The first slit portion 14 includes three slits 18 that are engraved over a predetermined length in the axial direction from the front end surface 12a of the cylindrical main body 12, and thereby the main portion 20 formed in three divisions. Each can be elastically bent in the radial direction. A tapered surface 22 is formed on the outer peripheral surface of each main body portion 20 of the first slit 14. Further, the inner peripheral surface of each main body portion 20 of the first slit portion 14 acts as a cylindrical bar gripping surface 24 in cooperation with each other. Therefore, in the first slit portion 14, by applying pressure inward in the radial direction to each tapered surface 22, each main body portion 20 is elastically bent and the bar gripping surface 24 is reduced in diameter, and the chuck 10 is closed. The bar is fixed and gripped in a fixed manner. When the radial pressure on the first slot 14 is released, each main body portion 20 is elastically restored, the bar gripping surface 24 is expanded, the chuck 10 is opened, and the bar is removed. release.

  The second slit portion 16 includes three slits 26 which are engraved over a predetermined length in the axial direction from the rear end surface 12b of the cylindrical main body 12, and thereby the main portion 28 formed in three parts is divided. Each can be elastically bent in the radial direction. An inner cylinder member 30 having a corresponding slot is attached to an inner peripheral surface area adjacent to the rear end surface 12b of the cylindrical main body 12. That is, the inner cylinder member 30 is provided with three slits 32 at positions corresponding to the three slits 26 of the cylindrical main body 12, whereby each of the inner cylinder portions 34 formed into three parts is elastic in the radial direction. Can be bent flexibly. The inner cylinder member 30 is a base end portion 36 having no slit 32, and is fixed to the inner peripheral surface of the cylindrical main body 12 with an adhesive, for example. The inner peripheral surface is slidably contacted. The axial end surface 30 a on the slit 32 side of the inner cylinder member 30 is disposed on substantially the same plane as the rear end surface 12 b of the cylindrical main body 12.

  On the outer peripheral surface of each main body portion 28 of the second slit portion 16, a male screw portion 38 that acts in cooperation with each other is provided. Further, the inner peripheral surface of each inner cylindrical portion 34 of the inner cylindrical member 30 attached to the cylindrical main body 12 works as a cylindrical bar gripping surface 40 in cooperation with each other. Therefore, the second slit portion 16 applies a pressure inward in the radial direction to each male screw portion 38, whereby each main body portion 28 and each inner cylinder portion 34 bend, and the bar gripping surface 40 is reduced in diameter. Hold the bar. When the radial pressure on the second slit 16 is released, each main body portion 28 and each inner cylinder portion 34 are restored, the bar gripping surface 40 is expanded, and the bar is released.

  As shown in FIG. 3, in the chuck 10, an annular recess 42 extending in the circumferential direction along the outer peripheral surface may be formed in a connection region between each inner cylindrical portion 34 and the proximal end portion 36 of the inner cylindrical member 30. preferable. The annular recess 42 has the effect of reducing the thickness of the inner cylinder member 30 at that portion and improving the flexibility of each inner cylinder portion 34 with respect to the proximal end portion 36. Further, it is desirable that the outer peripheral surface 34a of each inner cylinder portion 34 extends in a tapered shape from the axial end surface 30a toward the annular recess 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. There is an advantage that the frictional force between each main body portion 28 and each inner cylinder portion 34 is reduced.

  According to the chuck 10 having the above-described configuration, 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. Even if the bar material is gripped only in the local annular regions of the material gripping surfaces 24 and 40, the bar material is gripped by the chuck 10 at two locations separated in the axial direction. Therefore, for example, in an automatic lathe, when a long bar material is gripped by the chuck 10 and the tip machining portion is turned, the bar material is essentially bent and has a non-uniform outer diameter. However, due to the excellent bar holding function of the chuck 10 itself, it is possible to suppress as much as possible the swing of the unprocessed portion of the bar that rotates at high speed.

  Further, in the chuck 10, the inner cylinder member 30 is installed at the rear end in the axial direction of the cylindrical main body 12, and the bar holding surface 40 having an inner diameter smaller than the inner diameter of the cylindrical main body 12 is formed. In this case, the inner diameter of the bar holding surface 40 may be a size that does not make it difficult to insert the bar into the chuck 10 when no pressure is applied to the second slit 16. Nevertheless, according to the chuck 10, the bar gripping surface 40 can be elastically reduced to an inner diameter as close as possible to the outer diameter of the bar, so that the deflection of the bar can be sufficiently suppressed. The processing accuracy (dimensional accuracy, concentricity, cylindricity, surface roughness, etc.) can be remarkably improved. At this time, the first slit portion 14 needs a gripping pressure that allows the rod material to be firmly fixed and gripped, but the second slit portion 16 is not so strong as to fix the rod material firmly. Even if it is not necessary, it is only necessary to obtain a gripping pressure that can sufficiently suppress the deflection of the bar.

  The following two methods can be proposed as a method for manufacturing the chuck 10. In the first method, three slits 18 and 26 are formed by machining in predetermined regions of the front end and the rear end of the cylindrical main body 12 where the slits 18 and 26 are not formed. In a separate process, three slits 32 are formed by machining in a predetermined region at the rear end of the inner cylinder member 30 where the slits 32 are not formed. Next, the inner cylinder member 30 is fixed to the rear end portion of the cylindrical main body 12 using an adhesive or the like as described above while aligning the slits 26 and 32. In the second method, first, the inner cylinder member 30 not formed with the slit 32 is fixed to the rear end portion of the cylindrical main body 12 where the slits 18 and 26 are not formed using an adhesive or the like as described above. . Next, the first slit 14 is formed by cutting three slits 18 in a predetermined region of the front end of the cylindrical body 12 by machining. Further, a cutting blade is put into a predetermined region at the rear end of the cylindrical main body 12 and the inner cylindrical member 30, and each of the three slits 26 and 32 is formed to form the second slit 16. In any method, the chuck 10 can be manufactured by forming the second slit portion 16 in a subsequent process using a conventional chuck having only the first slit portion.

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

  The bar gripping device 50 elastically deforms the chuck 10 concentrically installed in the inner tip region of the rotation main shaft 52 and the first and second slit portions 14 and 16 of the chuck 10 to elastically deform the slit portions 14. , 16 is provided with an operating mechanism 58 for releasably gripping the bar. The actuating mechanism 58 includes a sleeve member 60 that is concentrically accommodated in the rotary main shaft 52 so as to be axially slidable, and a drive device 62 that moves the sleeve member 60 in the main shaft 52 in the axial direction. The driving device 62 can employ a known configuration in a conventional general chuck operating mechanism, and thus the description thereof is omitted.

  The sleeve member 60 is a hollow cylindrical body that can receive a bar, and an internal thread portion 64 that can be screwed into each external thread portion 38 of the chuck 10 is provided 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 the male screw portion 38 and the female screw portion 64. Therefore, the chuck 10 is displaced in the axial direction along with the sleeve member 60 when the sleeve member 60 of the operating mechanism 58 moves in the axial direction within the main shaft 52. Note that such a connection structure using screw parts is generally advantageously employed to facilitate replacement of the chuck 10. If it supplements, the chuck | zipper 10 which can be replaced | exchanged easily is equipped with the groove | channel 44 (FIG. 1) extended from the approximate center of the axial direction of the cylindrical main body 12 to the rear end surface 12b in the predetermined angular position of the outer peripheral surface of the cylindrical main body 12. The groove 44 receives a detent 66 that fixes the chuck 10 to the rotation main shaft 52 in the rotation direction when the chuck 10 is mounted on the rotation main shaft 52.

  A tapered working surface 68 that can be engaged with each tapered surface 22 of the first slit portion 14 of the chuck 10 is formed in the tip region of the rotation main shaft 52 that surrounds the chuck 10. Therefore, as the chuck 10 is displaced in the direction (backward in the axial direction) of being pulled into the main shaft 52 by the operating mechanism 58, each tapered surface 22 of the first slit portion 14 is pressed against the working surface 68 of the rotary main shaft 52. Thereby, pressure inward in the radial direction is applied to each tapered surface 22, the bar gripping surface 24 is reduced in diameter, and the first slit portion 14 is closed. When the chuck 10 is displaced from the main shaft 52 by the operating mechanism 58 from this closed state (forward in the axial direction), each tapered surface 22 of the first slit portion 14 acts on the working surface 68 of the rotary main shaft 52. Detach from. Thereby, the radial direction pressure to the 1st slot part 14 is cancelled | released, the rod-shaped holding | grip surface 24 expands, and the 1st slot part 14 will be in an open state.

  In the bar holding device 50, the operating mechanism 58 elastically deforms the first and second slit portions 14 and 16 of the chuck 10 by the operations related to each other as described below, that is, a series of operations of the sleeve member 60. By doing so, the bar can be firmly held by the chuck 10. First, the chuck 10 is set in an open state, a long bar is inserted into the inside from the rear end of the rotation main shaft 52, passed through the sleeve member 60, and supplied to the chuck 10. Then, the operating mechanism 58 is started in a state in which a required processing length portion of the bar is protruded from the chuck 10, and the chuck 10 is displaced in a direction to be pulled into the main shaft 52 integrally with the sleeve member 60. As a result, first, the bar holding surface 24 of the first slit portion 14 is reduced in diameter as described above, and the bar is firmly held.

  The movement of the chuck 10 in the axial direction stops when each tapered surface 22 of the first slit 14 of the chuck 10 is engaged with the action surface 68 of the rotary spindle 52. In this state, the operation mechanism 58 is continuously operated, 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 thread surface 70 of the female thread portion 64 of the sleeve member 60 is strongly pressed against the thread surface 72 of the thread portion of each male thread portion 38 of the second slit portion 16 of the chuck 10. It is done. Due to the contact surface pressure P at this time, a pressure inward in the radial direction is applied to the threaded surface 72 of each male threaded portion 38, each inner tubular portion 34 of the inner tubular member 30 is bent, and the bar gripping surface 40 is reduced in diameter. (Arrow Q), the second slit 16 is closed. In this way, the bar gripping surface 40 of the second slot 16 grips the bar following the first slot 14.

  From the closed state of the second slit 16, the operating mechanism 58 is operated to move the sleeve member 60 in the direction in which the chuck 10 is pushed out from the main shaft 52. Then, the contact surface pressure that the thread surface 70 of the female thread portion 64 of the sleeve member 60 applies to the thread surface 72 of each male thread portion 38 of the second slit portion 16 disappears. Thereby, the radial direction pressure to the 2nd slit part 16 is cancelled | released, and the bar material gripping surface 40 is expanded in diameter, and the 2nd slit part 16 will be in an open state. Subsequent or substantially simultaneously, the first slit 14 is opened as described above, and the bar is released from the chuck 10.

  As described above, in the bar gripping device 50, the second slit 16 of the chuck 10 is elastically deformed by using the contact surface pressure between the male thread 38 of the chuck 10 and the female thread 64 of the sleeve member 60. ing. 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. Furthermore, with such a configuration, after the rod member is first firmly fixed and gripped by the first slit portion 14 by the series of axial movements of the sleeve member 60, the second slit portion 16 The bar can be gripped with a gripping pressure that can sufficiently suppress the deflection of the bar. Here, the additional axial movement of the sleeve member 60 for applying a gripping pressure to the second slit 16 also acts to increase the bar gripping pressure in the first slot 14. In a lathe, it is indispensable for gripping a bar material as close as possible to the part to be turned, in order to perform highly accurate machining, but the bar gripping device 50 satisfies such a requirement. To meet.

  According to the bar gripping device 50 having the above-described configuration, the bar can be obtained with high precision (without providing a bar steadying device) by providing the high-performance chuck 10 that can suppress the deflection during rotation of the bar. Dimensional accuracy, concentricity, cylindricity, surface roughness, etc.). Therefore, in an automatic lathe in which the bar gripping device 50 is built in the rotary spindle 52, an increase in equipment cost is avoided and the structure of the automatic machining system is prevented from becoming complicated.

  Further, in the bar holding device 50, the operation mechanism 58 is configured to continuously elastically deform the first and second slit portions 14 and 16 of the chuck 10 by a series of operations of the sleeve member 60. The configuration of 58 is extremely simple. In particular, the second slit portion 16 of the chuck 10 utilizes the contact surface pressure between the male screw portion 38 and the female screw portion 64 of the sleeve member 60 that are employed for facilitating replacement of the chuck 10. Since the material gripping pressure is obtained, the operation mechanism 58 has an advantage that it can be used without modifying the conventionally used structure.

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

  The second slit 82 of the chuck 80 includes three slits 84 engraved over a predetermined length in the axial direction from the rear end surface 12b of the cylindrical main body 12, and thereby the main body formed into three parts. Each of the portions 86 can be elastically bent in the radial direction. 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. The cylindrical main body 12 has an inner diameter smaller than that of the central region in the region adjacent to the rear end surface 12b, and thereby cooperates with the inner peripheral surface of each main body portion 86 of the second slit portion 82. A cylindrical bar gripping surface 90 is formed. Therefore, the second slit portion 82 applies a pressure inward in the radial direction to each male screw portion 88, whereby each main body portion 86 bends, and the bar gripping surface 90 is reduced in diameter to grip the bar. When the radial pressure on the second slot 82 is released, each main body portion 86 is restored, the bar gripping surface 90 is expanded, and the bar is released.

  The bar gripping surface 90 of the second slot 82 of the chuck 80 has an inner diameter dimension that does not make it difficult to insert the bar into the chuck 80 when no pressure is applied to the second slot 82. If you have. In the chuck 80, it is preferable to form an annular recess 92 extending in the circumferential direction along the outer peripheral surface between each male screw portion 88 of the second slit portion 82 and the central region of the cylindrical main body 12. The annular recess 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.

  Also with the chuck 80 having the above-described configuration, the same operational effects as the chuck 10 can be obtained. In other words, the excellent bar gripping function of the chuck 80 itself makes it possible to suppress, as much as possible, the swinging of the rear unprocessed portion of the bar that rotates at high speed. Moreover, since the inner cylinder member 30 is unnecessary in the chuck 80, the number of parts and the number of manufacturing steps can be reduced. Further, the chuck 80 can also constitute the bar gripping device 50 in combination with the operation mechanism 58 described above. In that case, the processing accuracy of the bar material by the automatic lathe can be remarkably improved.

  8 and 9 show a chuck 100 according to a third embodiment of the present invention. The chuck 100 is obtained by removing the inner cylinder member 30 in the chuck 10 and forming the second slit 102 in an integral structure. 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 portion 102 of the chuck 100 includes three slits 104 engraved over a predetermined length in the axial direction from the rear end surface 12b of the cylindrical main body 12, and thereby the main body formed into three parts. Each of the portions 106 can be elastically bent in the radial direction. A tapered surface 108 extending adjacent to the rear end surface 12 b is provided on the outer peripheral surface of each main body portion 106 of the second slit portion 102. The cylindrical main body 12 has an inner diameter smaller than that of the central region in a region adjacent to the rear end surface 12b, and thereby cooperates with the inner peripheral surface of each main body portion 106 of the second slit portion 102. A cylindrical bar gripping surface 110 is formed. Therefore, the second slit 102 applies a pressure inward in the radial direction to each tapered surface 108, whereby each main body portion 106 is bent and the bar gripping surface 110 is reduced in diameter to grip the bar. When the radial pressure on the second slot 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 portion 102 of the chuck 100 has a configuration in which a gripping pressure is obtained by the tapered surface 108 that is inclined in substantially the same direction as the tapered surface 22 of the first slit portion 14. The bar gripping surface 110 of the second slit 102 of the chuck 100 has an inner diameter dimension that does not make it difficult to insert the bar into the chuck 100 when no pressure is applied to the second slot 102. If you have. In the chuck 100, a shoulder surface 112 extending substantially parallel to the front end surface 12a is formed between each tapered surface 22 of the first slit portion 14 and the front end surface 12a of the cylindrical main body 12.

The same effect as the chuck 10 can be obtained by the chuck 100 having the above configuration. That is, the excellent bar gripping function of the chuck 100 itself can suppress as much as possible the swing of the unprocessed portion of the back of the bar that rotates at high speed. Moreover, since the inner cylinder member 30 is not necessary in the chuck 100, the number of parts and the number of manufacturing steps can be reduced.
In the chuck 100 as well, as in the chuck 10 shown in FIGS. 1 to 3, the second slit 102 can be configured by assembling the inner cylinder member on the rear end side of the cylindrical body 12. . Further, 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 cylindrical main body 12.

The above-described chuck 100 can be combined with an operation mechanism having a configuration different from that of the above-described operation mechanism 58 to constitute the bar gripping device 120 shown in FIG.
FIG. 10 shows a second embodiment of the bar gripping device 120 according to the present invention provided with the chuck 100 in a state where it is built in the rotary spindle 122 of an automatic lathe. Similar to the rotation spindle 52 shown in FIG. 4, the rotation spindle 122 is installed on a spindle head (not shown) of an automatic lathe and is driven to rotate by a drive source (not shown) while firmly gripping the rod to be processed. Is done. The rotation main shaft 122 has a hollow cylindrical structure, and an elongated bar is fed from the rear end to the inside.

  The bar gripping device 120 elastically deforms the chuck 100 and the first and second slit portions 14 and 102 of the chuck 100 that are concentrically installed in the inner tip region of the rotary spindle 122, and these slit portions 14. , 102 is provided with an operating mechanism 124 for releasably gripping the bar. The operation mechanism 124 includes a sleeve member 126 that is concentrically accommodated in the rotation main shaft 122 so as to be axially slidable, and a drive device 128 that moves the sleeve member 126 in the axial direction within the main shaft 122. The driving device 128 can employ a known configuration in a conventional general chuck operating mechanism, and thus the description thereof is omitted.

  The sleeve member 126 is a hollow cylindrical body that can receive a bar, and the chuck 100 can be accommodated in the front end region of the inner surface so as to be slidable in the axial direction. A tapered first working surface 130 that can be engaged with each tapered surface 22 of the first slit portion 14 of the chuck 100 is formed in the vicinity of the inner surface front end of the sleeve member 126. In addition, in the inner surface region of the sleeve member 126 that is separated from the first working surface 130 by a predetermined distance, a tapered second working surface 132 that can be engaged with each tapered surface 108 of the second slit portion 102 of the chuck 100. Is formed. The distance between the first working surface 130 and the second working surface 132 of the sleeve member 126 is set to a dimension that allows the first and second working surfaces 130 and 132 to simultaneously contact the tapered surfaces 22 and 108 of the chuck 100.

  Between the rear end surface 12 b of the chuck 100 and the sleeve member 126, the chuck 100 is pushed out from the sleeve member 126, that is, the taper surfaces 22 and 108 are separated from the first and second working surfaces 130 and 132. A compression spring 134 is installed. On the other hand, a cap 136 having a locking surface 138 that can be engaged with each shoulder surface 112 of the chuck 100 is detachably attached to the tip of the rotating main shaft 122. When the cap 136 is attached to a predetermined position of the rotation main shaft 122, the locking surface 138 engages with each shoulder surface 112 of the chuck 100 and holds the chuck 100 so as not to fall off from the sleeve member 126. In this state, the chuck 100 is fixedly supported between the sleeve member 126 and the cap 136 under the bias of the compression spring 134. When the chuck 100 is replaced, the cap 136 may be removed from the rotating main shaft 122 and the chuck 100 may be extracted from the sleeve member 126.

  In the bar gripping device 120, the operating mechanism 124 elastically deforms the first and second slit portions 14 and 102 of the chuck 100 by the operations related to each other as described below, that is, a series of operations of the sleeve member 126. By doing so, the bar can be firmly held by the chuck 100. First, the chuck 100 is set in an open state, and a long bar is inserted into the inside thereof from the rear end of the rotary main shaft 122 and is supplied to the chuck 100 through the sleeve member 126. Then, in a state where a required processing length portion of the bar is protruded from the chuck 100, the operation mechanism 124 is started, and the sleeve member 126 is moved in the direction in which the sleeve member 126 is pushed out from the rotating main shaft 122 (forward in the axial direction). At this time, since the chuck 100 is locked in the axial direction forward movement in the main shaft 122 by the cap 136, the first working surface of the sleeve member 126 is fitted to each tapered surface 22 of the first slit 14 of the chuck 100. The second working surface 132 of the sleeve member 126 is pressed against each tapered surface 108 of the second slit 102 of the chuck 100 at the same time.

  In this manner, radial inward pressure is applied 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, and the second slit portion 102. A pressure inward in the radial direction is applied to each of the taper surfaces 108 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. Thereby, the bar is gripped by the bar gripping surfaces 24 and 110 of the first and second slit portions 14 and 102 of the chuck 100.

  From this closed state, when the sleeve member 126 of the operating mechanism 124 is moved in the direction in which the sleeve member 126 is pulled into the rotary main shaft 122 (backward in the axial direction), the chuck 100 is held in a state of being pressed against the cap 136 under the bias of the compression spring 134. Therefore, the first and second working surfaces 130 and 132 of the sleeve member 126 are simultaneously detached from the tapered surfaces 22 and 108 of the first and second slit portions 14 and 102 of the chuck 100, respectively. As a result, the radial pressure applied to the first and second slit portions 14 and 102 is released, the diameters of the bar gripping surfaces 24 and 110 are increased, and the first and second slit portions 14 and 102 are simultaneously moved. The bar is released from the chuck 100 in the open state.

  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, in the lathe, as described above, it is an essential requirement to perform high-precision machining that the bar is firmly held as close as possible to the portion to be turned. In order for the bar gripping device 120 to satisfy such requirements, the axial movement of the sleeve member 126 in the second axial direction is performed until the bar is firmly fixed and gripped by the first slit portion 14. It is necessary to configure so as not to be hindered by the engagement with the slot 102. For this purpose, when the first slit 14 firmly holds and holds the bar, the second slot 102 does not fix the bar firmly and sufficiently suppresses the deflection of the bar. It is important to adjust the amount of bending of the first and second slit portions 14 and 102, the inner diameter dimensions of the rod material gripping surfaces 24 and 110 when no load is applied, etc. so that the bar material can be gripped as much as possible. .

  According to the bar gripping device 120 having the above-described configuration, the bar can be obtained with high precision (without providing a bar steadying device) by providing the high-performance chuck 100 that can suppress the deflection during rotation of the bar. Dimensional accuracy, concentricity, cylindricity, surface roughness, etc.). Therefore, in an automatic lathe in which the bar holding 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 prevented from becoming complicated. Further, in the bar gripping device 120, the operation mechanism 124 is configured to elastically deform the first and second slit portions 14 and 102 of the chuck 100 simultaneously by a series of operations of the sleeve member 126. The configuration is extremely simple.

1 is a cross-sectional view of a chuck according to a first embodiment of the present invention. It is an end elevation from the direction of arrow II of the chuck of FIG. It is a partial expanded sectional view of the chuck | zipper of FIG. It is sectional drawing shown in the state mounted in the rotation main axis | shaft of the automatic lathe of the bar holding | grip apparatus by the 1st Embodiment of this invention. It is a partial expanded sectional view of the bar holding apparatus of FIG. It is sectional drawing of the chuck | zipper by the 2nd Embodiment of this invention. It is an end view from the arrow VII direction of the chuck | zipper of FIG. It is sectional drawing of the chuck | zipper by the 3rd Embodiment of this invention. It is an end view from the arrow IX direction of the chuck of FIG. It is sectional drawing shown in the state mounted in the rotation main axis | shaft of the automatic lathe with the bar holding | grip apparatus by the 2nd Embodiment of this invention.

Explanation of symbols

10, 80, 100 Chuck 12 Cylindrical body 14 First slot 16, 82, 102 Second slot 18, 26, 32, 84, 104 Slit 22, 108 Tapered surface 24, 40, 90, 110 Bar material gripping surface 30 Inner cylinder member 38, 88 Male thread portion 50, 120 Bar material gripping device 52, 122 Rotating spindle 58, 124 Actuating mechanism 60, 126 Sleeve member 62, 128 Drive device 64 Female thread portion 68 Working surface 70, 72 Screw Surface 130 First working surface 132 Second working surface

Claims (11)

  A chuck having an elastically deformable gripping portion provided on the cylindrical main body and capable of releasably gripping a bar material on the gripping portion, wherein the gripping portions are provided at a plurality of positions spaced apart in the axial direction of the cylindrical main body. A chuck characterized in that it is made.   The said holding | grip part consists of the 1st slit part provided in the axial direction one end of the said cylindrical main body, and the 2nd slit part provided in the axial direction other end of this cylindrical main body. Chuck.   The chuck according to claim 2, wherein tapered surfaces are respectively formed along outer peripheral surfaces of the first and second slit portions.   The chuck according to claim 3, wherein the tapered surface of one of the first and second slits is a thread surface of an external thread.   The chuck according to claim 3 or 4, wherein an inner cylindrical member having a corresponding slit portion is attached to one inner peripheral surface of each of the first and second slit portions.   A chuck according to any one of claims 1 to 5, and an operating mechanism that elastically deforms the gripping portion of the chuck and causes the gripping portion to releasably grip a bar. Bar gripping device.   The bar gripping device according to claim 6, wherein the operating mechanism elastically deforms the plurality of gripping portions of the chuck by operations related to each other.   The bar gripping device according to claim 6 or 7, wherein the operating mechanism includes a sleeve member that is arranged concentrically with the chuck and is movable in the axial direction, and a drive device that moves the sleeve member in the axial direction.   4. The bar gripping device comprising: the chuck according to claim 3; and an operating mechanism that elastically deforms the gripping portion of the chuck and causes the gripping portion to grip the bar in a releasable manner. First and second working surfaces that are axially movable to removably engage the respective tapered surfaces of the first and second slit portions of the chuck and press the tapered surfaces when engaged. A bar holding device characterized by comprising:   5. A bar gripping device comprising: the chuck according to claim 4; and an operating mechanism that elastically deforms the gripping portion of the chuck and causes the gripping portion to grip the bar in a releasable manner. An axially movable internal thread that engages with the external thread constituting the one tapered surface of the chuck is removably engaged with the other tapered surface of the chuck and presses the tapered surface during engagement. A bar gripping device comprising a working surface.   An automatic lathe, wherein the bar gripping device according to any one of claims 6 to 10 is incorporated in a rotary spindle.

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