WO2015155827A1

WO2015155827A1 - Collet chuck, chuck device, and method for manufacturing machined product

Info

Publication number: WO2015155827A1
Application number: PCT/JP2014/060139
Authority: WO
Inventors: 夢周金; 裕司小口
Original assignee: 株式会社ダイヤ精機製作所
Priority date: 2014-04-08
Filing date: 2014-04-08
Publication date: 2015-10-15
Also published as: JPWO2015155827A1; KR101801502B1; KR20160102567A; TWI574773B; JP6208851B2; TW201538270A

Abstract

The present invention improves shape accuracy of a machined product by preventing shifting of gripping position in an axial direction, thereby achieving a reduction in the rate of defects. This collet chuck (10) is equipped with a cylindrical main collet (11) and a cylindrical secondary collet (12) that is disposed on the inner periphery side of the main collet (11) so as to be movable in the axial direction with respect to the main collet (11). The main collet (11) has multiple slits (11a) that extend in the axial direction, a surface to be pressed (11b) that is provided on the outer periphery of the main collet and formed into a tapered shape or a reverse-tapered shape toward one side in the axial direction, said surface to be pressed being a surface to which a pressure for increasing/decreasing the inner diameter of the main collet (11) is applied, and a main-side inclined surface (11c) that is provided on the inner periphery and formed into a reverse-tapered shape obliquely inclined toward the tip side in the axial direction. The secondary collet (12) has multiple slits (12a) that extend in the axial direction, a gripping surface (12b) that is provided on the inner periphery of the secondary collet and grips a member to gripped, and a secondary-side inclined surface (12c) that is provided on the outer periphery and formed into a reverse-tapered shape for making contact with the main-side inclined surface.

Description

Collet chuck, chuck device, and manufacturing method of processed product

The present invention relates to a collet chuck, a chuck device, and a method of manufacturing a processed product, and more particularly to a fixing structure at the time of processing a part suitable for improving the processing accuracy in the axial direction of a processed part.

Generally, various machine tools used when machining precision parts require chuck devices for gripping materials and tools. For this chuck device, for example, a collet chuck that has a slit and can be expanded and contracted in the radial direction is used. The collet chuck is provided with a pressure surface to be tapered or inversely tapered, and the collet chuck opens and closes by driving an action member such as a sleeve or a drawbar having a pressure surface corresponding to the pressure surface in the axial direction. Operates and grips parts, tools, and the like by the gripping portion. Such a chuck device is particularly suitable for performing various types of front surface processing while holding the work material on the main shaft, and then performing the back surface processing by transferring the front end of the semi-processed product after the front surface processing to the rear surface main shaft. This is an extremely important part for ensuring the shape accuracy of the processed parts.

As a conventional chuck device, there is known a device configured such that a cylindrical sleeve having a slit can be accommodated inside a normal collet chuck in order to grip work materials having different diameters ( See

Patent Documents

1 and 2 below). There is also known a chuck structure in which a clamp arm is accommodated inside a collet chuck (see Patent Document 3 below).

JP 2007-152509 A Japanese Utility Model Publication No. 51-39899 Japanese Utility Model Publication No.57-7448

However, in the conventional chuck device described above, when a process with a large load is performed in the axial direction such as drilling or broaching while the work material is gripped, the work material escapes in the axial direction with respect to the grip portion. As a result, the processing accuracy in the axial direction of the processed part deteriorates or the gripped surface of the processed part is damaged, which may cause a defect. In particular, when the load is applied during the above-described back surface processing, an axial displacement occurs between the front surface processing portion and the back surface processing portion. In addition, when the outer surface of the semi-processed product has a reverse taper shape that is inclined obliquely toward the base end side in the axial direction, the semi-processed product easily escapes to the front end side of the chuck device when processing the back surface. It becomes easy to do.

Therefore, the present invention solves the above-mentioned problems, and the problem is that the shape accuracy of the processed part can be improved and the defect rate can be reduced by preventing the gripping position from shifting in the axial direction. It is to realize a collet chuck, a chuck device, and a manufacturing method of a processed product.

In view of such circumstances, the collet chuck of the present invention includes a cylindrical main collet, and a cylindrical sub-collet that is arranged to be movable in the axial direction relative to the main collet on the inner peripheral side of the main collet. The main collet is a plurality of slits extending in the axial direction and a surface provided on the outer periphery and pressed to expand and contract the inner diameter of the main collet, on either side of the axial direction A pressurized surface configured in a tapered or reverse tapered direction, and a main-side inclined surface configured in a reverse tapered shape provided on the inner periphery and inclined obliquely toward the distal end side in the axial direction, The sub-collet is configured in a plurality of slits extending in the axial direction, a gripping surface provided on the inner periphery for gripping a gripped material, and an inversely tapered shape provided on the outer periphery and in contact with the main inclined surface A secondary inclined surface. To. In other words, this collet chuck is an outer diameter gripping type collet chuck that grips the outer diameter of the material to be gripped.

According to the present invention, the inner diameter of the main collet expands and contracts depending on whether pressure is applied to the surface to be pressed, whereby the main-side inclined surface of the main collet drives the auxiliary-side inclined surface of the sub-collet in contact with the main collet. Since the inner diameter of the sub collet expands and contracts, the material to be gripped can be gripped from the outside by the gripping surface provided on the inner periphery of the sub collet. In this gripping state, if a force is applied to the gripped material in the axial direction from the distal end side, the secondary collet that grips the gripped material tends to move toward the base end side in the axial direction with respect to the main collet. However, since the secondary collet is in contact with the main inclined surface, the internal diameter of the secondary collet is reduced and the gripping force of the secondary collet on the gripped material is increased. Misalignment is less likely to occur. In addition, the occurrence of damage to the surface portion of the gripping material in contact with the gripping surface is suppressed by reducing the displacement of the gripping material.

In the present invention, it is preferable to further include an axial spring that biases the sub-collet toward the distal end side in the axial direction with respect to the main collet. According to this, even when the gripping force is increased by receiving the force toward the proximal end in the axial direction with respect to the main collet in the gripping state of the material to be gripped, the main collet has shifted to the released state. Sometimes the secondary collet is biased by the axial spring toward the tip in the axial direction, making it easier for the secondary collet to release the gripped material, and the secondary collet compressing the axial spring by inserting the gripped material Even when the gripping material is gripped while being pushed to the base end side of the main collet, it is easy to return to the original position when the gripping material is released.

In the present invention, it is preferable that the sub collet has a positioning locking portion that locks and positions the gripped material from the base end side in the axial direction when in the released state. According to this, the position accuracy of the auxiliary collet and the material to be grasped in the axial direction can be ensured by grasping the material to be grasped in contact with the positioning locking portion. The positioning locking portion may be provided on a part of the gripping surface (for example, the base end in the axial direction of the gripping surface), and is separated from the gripping surface (for example, on the base end side in the axial direction). It may be provided at a position. At this time, the gripping surface of the sub-collet may have an engaging gripping portion that protrudes in the radial direction to enable jumping and gripping. In this case, it is desirable that the positioning locking portion is provided apart from the proximal end side in the axial direction of the engagement gripping portion.

In the present invention, it is preferable that the gripping surface of the sub-collet is a frustum-shaped surface that is inclined obliquely toward the tip end side in the axial direction. That is, it is preferable that the gripping surface is configured in a reverse taper shape that is inclined obliquely toward the tip end side in the axial direction if the collet chuck is an outer diameter gripping type as described above. According to this, when the gripping surface of the sub-collet is configured in a reverse taper shape according to the shape of the material to be gripped, the material to be gripped will receive the processing force when subjected to an axial processing force or impact. Further, the possibility that the position shifts to the tip side in the axial direction opposite to the direction of the impact increases, and the above configuration of the present invention can further prevent the position shift and avoid the damage to the gripped material. Become prominent.

In the present invention, it is preferable that the main collet is provided with a guide surface extending in the axial direction on the inner periphery, and the sub-collet is provided with a guided surface in sliding contact with the guide surface and guided in the axial direction on the outer periphery. According to this, when the guided surface of the main collet is guided in the axial direction by the guide surface of the main collet, when the secondary collet moves in the axial direction with respect to the main collet, the axis deviation or angle of the gripping surface of the secondary collet Since the change is suppressed, it is possible to prevent the processing accuracy of the gripped material from being lowered even when the supply position of the gripped material (insertion depth with respect to the main collet) varies.

In this case, the slit of the main collet and the slit of the sub-collet are formed to extend from the distal end edge in the axial direction toward the proximal end side, and the guide surface is an axis line with respect to the main inclined surface. Preferably, the guided surface is formed in a region disposed on the proximal side in the axial direction with respect to the sub-inclined surface. According to this, while the slot of the main collet and the slot of the sub-collet are both formed from the tip edge in the axial direction, the region on the tip side in the axial direction is configured to expand and contract, The guide surface is provided in a region arranged on the base end side in the axial direction with respect to the main inclined surface, and the guided surface is provided in a region arranged on the base end side in the axial direction with respect to the sub-side inclined surface. Since it is provided, since the deformation of the guide surface and the guided surface when the main collet and the sub-collet are opened and closed is reduced, it is possible to suppress a decrease in guiding accuracy in the axial direction of the sub-collet with respect to the main collet.

In the present invention, a main side step is provided on the inner periphery of the main collet, and a sub side step is provided on the outer periphery of the sub collet in the axial direction with respect to the main side step. It is preferable that the sub collet is prevented from coming off toward the tip end side in the axial direction with respect to the main collet by the sub side step contacting the main side step. According to this, the sub collet is prevented from coming off toward the front end side in the axial direction with respect to the main collet by the engagement structure of the main side step portion and the sub side step portion. The secondary collet can be prevented from falling out of the main collet when the material to be grasped is discharged by a knockout pin or the like. In addition, when the above-described axial spring is provided, the secondary collet is returned to the retaining position by the axial spring when the gripping material is released. On the other hand, the secondary collet can always be set to the initial position. Note that the structure for preventing the secondary collet from being removed from the primary collet is not limited to the configuration having the primary side stepped portion and the secondary side stepped portion, and as a result, the secondary collet is provided by a member provided separately from the collet chuck in the chuck device or machine tool. The collet may be held in the main collet.

In the present invention, it is preferable that at least one of the main-side inclined surface of the main collet and the auxiliary-side inclined surface of the sub-collet is formed with a groove that intersects with the axial direction. Since the corner portion of one inclined surface generated by providing this groove bites the other inclined surface, it is possible to reduce the positional deviation in the axial direction between the main collet and the sub-collet in the gripping state.

Next, the chuck device of the present invention is configured to be movable in the axial direction with the above-described collet chuck and pressurizes the main collet in the axial direction to expand and contract in the radial direction (to generate a reduced diameter on the inner periphery). And a working member. According to this, when the acting member pressurizes the surface to be pressurized of the main collet, the main collet is operated, and the secondary side is interposed via the reverse tapered fitting structure of the primary side inclined surface and the secondary side inclined surface that are in contact with each other. The collet also works. For example, the diameter of the main collet is reduced by pressurizing the action member, whereby the diameter of the sub-collet is reduced and the object to be grasped is gripped. At this time, the surface to be pressed of the main collet is a surface pressed in the axial direction by the action member in order to expand and contract the inner diameter, and is tapered toward at least one side in the axial direction or It shall be comprised by reverse taper shape. In this case, the sub-collet is retained in the main collet by being prevented from coming off at the tip end in the axial direction, and the chuck device attaches the sub-collet to the tip end in the axial direction with respect to the main collet. It is preferable to further comprise a biasing axial spring.

Next, a method for manufacturing a processed product according to the present invention is a method for manufacturing a processed product in which the workpiece is processed by forming the processed product in a state where the workpiece is gripped by the chuck device. The collet chuck, and an action member configured to be movable in the axial direction and pressurizing the main collet in the axial direction to expand and contract in the radial direction (for example, to reduce the inner diameter). The main collet and the sub-collet are in a released state by disposing the operating member in a release driving position, and the workpiece is mounted on the inner peripheral side of the sub-collet, and then the operating member is The main collet and the sub-collet are placed in a gripping state by being placed in a grip driving position, and the workpiece is processed.

In the present invention, the sub-collet is held against the main collet by being prevented from coming off at the front end side in the axial direction, and the chuck device moves the sub-collet toward the front end side in the axial direction with respect to the main collet. It is preferable to further comprise a biasing axial spring. According to this, the secondary collet is prevented from slipping off toward the distal end side in the axial direction, and is urged toward the distal end side in the axial direction by the axial spring, so that the secondary collet is axially moved when the workpiece is released. Since the spring returns to the retaining position, the sub collet can always be set to the initial position with respect to the main collet before the workpiece is inserted. Therefore, when the workpiece is introduced, the accuracy of the introduction position of the workpiece in the axial direction with respect to the sub-collet can be increased, and as a result, the machining accuracy can be improved. Of course, it is possible to prevent the sub collet from falling out of the main collet when the workpiece is taken out (for example, when the gripping material is discharged by a knockout pin or the like). The structure for preventing the secondary collet from coming off from the main collet may be provided between the main collet as described above, or between a member provided separately from the collet chuck in the chuck device or machine tool. It may be provided.

In the present invention, the sub-collet has a positioning locking portion (for example, a base end in the axial direction of the gripping surface) that locks and positions the workpiece from the base end side in the axial direction when in the released state. It is preferable that the workpiece is gripped by the sub collet in a state of being abutted against the positioning locking portion when being mounted on the inner peripheral side of the sub collet. According to this, since the workpiece is gripped by the secondary collet while being abutted against the positioning locking portion, the axial position of the workpiece relative to the secondary collet can be made constant. It is possible to reduce the variation in the dimension in the axial direction of the product obtained by processing the workpiece, and to increase the shape accuracy in the axial direction of the product.

In this case, the chuck device further includes an axial spring that biases the secondary collet toward the distal end in the axial direction with respect to the primary collet, and the workpiece is mounted on the secondary collet. It is preferable that the workpiece is held by the sub collet in a state where the workpiece is abutted against the positioning locking portion and the axial spring is compressed. According to this, since the axial spring biases the secondary collet toward the distal end side in the axial direction, the workpiece can be mounted from the distal end side of the secondary collet so that the axial spring is compressed. Since the workpiece can be maintained in a state where it is abutted against the positioning locking portion, the workpiece can be reliably positioned when it is gripped by the sub-collet, and the workpiece is processed with respect to the sub-collet. The positional accuracy in the axial direction of the material can be further increased.

In the present invention, the first step of mounting the workpiece on a spindle and performing a front machining, and passing the workpiece after the front machining is transferred to a back spindle provided with the chuck device, It is preferable to include a second step of gripping the workpiece by the chuck device, and a third step of performing a back machining on the workpiece mounted on the back spindle. According to this, even when a processing force is applied to the base end side in the axial direction with respect to the work piece in the back surface processing, if the work piece tries to move to the base end side in the axial direction by the processing force, The gripping force on the workpiece increases due to the sliding contact structure between the sub-side inclined surface and the main-side inclined surface between the collet and the main collet. As a result, the displacement of the workpiece toward the proximal end in the axial direction is increased. It can be avoided. Therefore, the machining accuracy in the axial direction of the workpiece can be increased, and damage caused between the workpiece and the gripping surface of the sub collet can be reduced. Moreover, since the position shift in the axial direction of the workpiece during back surface processing can be prevented, the processing shift in the axial direction between the front surface processed portion and the back surface processed portion in the processed product can be reduced.

Furthermore, another collet chuck of the present invention comprises a cylindrical main collet, and a cylindrical sub-collet arranged on the outer peripheral side of the main collet so as to be movable in the axial direction with respect to the main collet, The main collet is a plurality of slits extending in the axial direction and a surface provided on the inner periphery and pressed to expand and contract the outer diameter, and is tapered toward either side in the axial direction or A pressure-receiving surface configured in an inversely tapered shape, and a main-side inclined surface provided on the outer periphery and configured to be inclined toward the tip end side in the axial direction, and the sub-collet is in the axial direction A plurality of slits extending to the outer periphery, a gripping surface provided on the outer periphery for gripping the object to be gripped, a sub-side inclined surface provided on the inner periphery and configured in a tapered shape to contact the main-side inclined surface, It is characterized by having. In other words, this collet chuck is an inner diameter gripping type collet chuck that grips the inner diameter of the material to be gripped.

Here, it is preferable to further include an axial spring that urges the sub-collet toward the distal end side in the axial direction with respect to the main collet. Further, the sub collet has a positioning locking portion that locks and positions the gripped material from the base end side in the axial direction when in the released state (for example, on the base end side in the axial direction of the gripping surface). ) Is preferable. Furthermore, it is preferable that the gripping surface of the sub collet is a frustum-shaped surface that is inclined obliquely toward the distal end side in the axial direction. That is, in the case of the inner diameter gripping type, this gripping surface is preferably configured in a tapered shape that is inclined obliquely toward the tip end side in the axial direction. Preferably, the main collet has a guide surface extending in the axial direction on the outer periphery, and the sub-collet has a guided surface in sliding contact with the guide surface and guided in the axial direction on the inner periphery. Further, in this case, the slit of the main collet and the slit of the sub-collet are formed so as to extend from the front end edge in the axial direction toward the base end side, and the guide surface is in relation to the main inclined surface. Preferably, the guided surface is formed in a region arranged on the base end side in the axial direction with respect to the sub-inclined surface. A main side step is provided on the outer periphery of the main collet, and a sub side step is provided on the inner periphery of the sub collet in the axial direction with respect to the main side step. It is preferable that the sub collet is prevented from coming off toward the front end side in the axial direction with respect to the main collet by the step part coming into contact with the main side step part. Furthermore, it is preferable that the gripping surface of the sub-collet has an engaging gripping portion protruding in the radial direction that enables jumping and gripping. In this case, it is desirable that the positioning locking portion is provided apart from the proximal end side in the axial direction of the engagement gripping portion. Moreover, it is preferable that the groove | channel of the direction which cross | intersects an axial direction is formed in at least any one surface of the main side inclined surface of a main collet, and the sub-side inclined surface of a sub collet.

This other collet chuck can be used in the above chuck device. That is, instead of the action member, the action member is configured to be movable in the axial direction and is used together with an action member that pressurizes the main collet in the axial direction and expands or contracts in the radial direction (so that the outer diameter is increased). At this time, the surface to be pressed of the main collet is a surface pressed in the axial direction by the action member in order to expand and contract the outer diameter, and is tapered toward at least one side in the axial direction. Or it shall be comprised by reverse taper shape. In this case, the sub-collet is retained in the main collet by being prevented from coming off at the tip end in the axial direction, and the chuck device attaches the sub-collet to the tip end in the axial direction with respect to the main collet. It is preferable to further comprise a biasing axial spring.

The chuck device using the another collet chuck is used in the method for manufacturing a processed product of the present invention, and the main collet and the sub-collet are in a released state by disposing the action member at a release drive position. Then, the workpiece is mounted on the outer peripheral side of the sub-collet, and then the working member is disposed at a grip driving position to bring the main collet and the sub-collet into a gripping state, thereby processing the workpiece. It is characterized by that. In this case, the sub-collet is held against the main collet by being prevented from coming off at the front end in the axial direction, and the chuck device moves the sub-collet toward the front end in the axial direction with respect to the main collet. It is preferable to further comprise a biasing axial spring. Further, the gripping surface of the sub-collet has a positioning locking portion that locks and positions the workpiece from the base end side in the axial direction when in the released state (for example, in the axial direction of the gripping surface Preferably, the workpiece is gripped by the sub-collet in a state of being abutted against the positioning locking portion when being mounted on the outer peripheral side of the sub-collet. At this time, the chuck device further includes an axial spring that biases the sub collet toward the front end in the axial direction with respect to the main collet, and the workpiece is mounted on the sub collet. It is preferable that the workpiece is held by the sub collet in a state where the workpiece is abutted against the positioning locking portion and the axial spring is compressed. Further, a first step of mounting the workpiece on a spindle and performing a front machining, and passing the workpiece after the front machining is completed to a back spindle including the chuck device, and the chuck on the back spindle It is preferable to include a second step of gripping the workpiece by an apparatus and a third step of performing a back machining on the workpiece mounted on the back spindle.

In the present invention, the taper shape means that the taper is tapered toward the distal end side in the axial direction, and the reverse taper shape is the taper shape toward the proximal end side in the axial direction. Say that. The cylindrical shape is typically a cylindrical shape, but includes an arbitrary cylindrical shape such as an elliptical cylindrical shape, a long cylindrical shape, and a rectangular cylindrical shape. Furthermore, the frustum-shaped surface means a surface having the shape of the side surface of the frustum, and is typically a truncated cone shape, but may be any shape such as an elliptical truncated cone shape, a long truncated cone shape, a truncated pyramid shape, etc. Includes frustum shape.

According to the present invention, a collet chuck, a chuck device, and a processed product manufacturing method capable of improving the shape accuracy of a processed part and reducing the defect rate by preventing the gripping position from shifting in the axial direction. It is possible to achieve an excellent effect that can be realized.

It is the front view (a) which shows the structure of 1st Embodiment of the collet chuck which concerns on this invention, longitudinal cross-sectional view (b), and sectional drawing (c) which shows the example of the workpiece | work corresponding to this collet chuck. It is the front view (a) and longitudinal cross-sectional view (b) of the main collet of 1st Embodiment. It is the front view (a), BB longitudinal cross-sectional view (b), and side view (c) of the sub collet of 1st Embodiment. It is a disassembled perspective view which shows the structure of embodiment of the chuck apparatus which concerns on this invention including the collet chuck of 1st Embodiment. It is a longitudinal cross-sectional view which shows the example of the internal structure of the chuck | zipper apparatus. It is the longitudinal cross-sectional view (a) which shows the releasing state of the chuck apparatus, and the longitudinal cross-sectional view (b) which shows a holding state. FIG. 5 is process diagrams (a) to (e) showing an embodiment of a method for manufacturing a processed product according to the present invention, and a longitudinal sectional view (f) showing a structure example of a workpiece. The front view (a) which shows 2nd Embodiment of the collet chuck which concerns on this invention, the longitudinal cross-sectional view (b) which shows a releasing state, the longitudinal cross-sectional view (c) which shows the state in the middle of transfer to a holding state, and a holding state It is a longitudinal cross-sectional view (d) shown. It is the longitudinal cross-sectional view (a) which shows the open state of 3rd Embodiment of the chuck | zipper apparatus which has another collet chuck based on this invention, and the longitudinal cross-sectional view (b) which shows a holding state.

[First Embodiment] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, a first embodiment of a collet chuck will be described with reference to FIGS. As shown in FIGS. 1 and 2, the collet chuck 10 of the present embodiment includes a main collet 11 configured as a whole (cylindrical in the illustrated example) and an axial tip inside the main collet 11. As shown in FIGS. 1 and 3, the secondary collet 12 is formed in a cylindrical shape (cylindrical in the illustrated example) as a whole, and the axial direction of the secondary collet 12 is inside the main collet 11. An axial spring 13 disposed and accommodated on the base end side of the main collet 11 and a spring receiver 14 attached to the base end of the main collet 11 in the axial direction and supporting the axial spring 13 from the base end side in the axial direction. Have.

The main collet 11 extends from the distal end edge in the axial direction to the proximal end side (the right side in the figure) and is formed in a range from the middle position to the middle position, and includes a plurality of slits 11a provided (three in the illustrated example) around the axis line. Yes. The base end portion of the slit 11a in the axial direction is a large circular (may be oval or elliptical) opening, and the portion on the tip end side (left side in the drawing) in the axial direction from this opening is It is configured in a slit shape having a certain width. A pressed surface 11b configured in an inversely tapered shape (conical frustum shape) obliquely toward the proximal end side in the axial direction is formed on the outer peripheral portion in the axial formation region of the slit 11a. On the distal end side of the pressurized surface 11b, there is formed an outer peripheral step portion 11p formed on a step surface facing the base end side in the axial direction and perpendicular to the axis.

The main collet 11 is configured such that the inner diameter of the main inclined surface 11c at the tip end portion in the axial direction is expanded and contracted by receiving pressure from a chuck sleeve (action member) described later on the pressed surface 11b. . The main-side inclined surface 11c is provided on the inner periphery of the portion of the main collet 11 that is on the most distal side. The main inclined surface 11c is a frustoconical surface having a predetermined taper angle along the axial direction, and has a reverse taper shape in which the inner diameter increases toward the distal end side of the main collet 11 in the axial direction. Yes. As shown in FIG. 2, annular grooves 11q1 and 11q2 orthogonal to the axis are formed on the main inclined surface 11c. Further, a cylindrical surface 11r disposed between the main-side inclined surface 11c and a main-side step portion 11e described later is formed in a portion adjacent to the base end side in the axial direction of the main-side inclined surface 11c. The cylindrical surface 11r has the same inner diameter as the smallest diameter portion at the proximal end edge in the axial direction of the main inclined surface 11c.

On the inner periphery of the main collet 11, a guide surface 11d made of a cylindrical surface having a constant inner diameter in the axial direction is formed in a region on the proximal end side in the axial direction with respect to the main inclined surface 11c. In addition, a main side step portion 11e having a step surface facing the proximal end in the axial direction is provided between the guide surface 11d and the main inclined surface 11c. In the case of the illustrated example, the guide surface 11d and the main side step portion 11e are formed in a region in the axial direction in which the pressed surface 11b is provided on the outer periphery. The said area | region is an area | region comprised in the main collet 11 more thickly than the part in the base end side of an axial direction. Further, as shown in FIG. 2, the step surface of the main-side step portion 11 e is directed to the base end side in the axial direction and has a tapered step surface 11 e 1 having a truncated cone-like taper inclined obliquely toward the inner peripheral side. The vertical step surface 11e2 is formed adjacent to the outer peripheral side of the tapered step surface 11e1 and orthogonal to the axis. The tapered step surface 11e1 is in contact with the cylindrical surface 11r, and the vertical step surface 11e2 is in contact with the guide surface 11d.

The sub-collet 12 includes a plurality of (three in the illustrated example) slits 12a around the axis extending from the front end edge in the axial direction to the base end side. The base end portion of the slit 12a in the axial direction is a large circular (may be oval or elliptical) opening, and the portion on the tip end side in the axial direction from the opening has a certain width. It has a slit shape. On the inner periphery of the sub-collet 12, in the axial region where the slit 12a is formed, in the illustrated example, the gripped material or workpiece (hereinafter simply referred to as “work W”) is provided at the most distal end side in the axial direction. .) Is formed. The gripping surface 12b only needs to be capable of gripping the outer diameter of the workpiece W by reducing the inner diameter of the sub-collet 12, and is generally configured as a cylindrical surface having a constant inner diameter in the axial direction. Good. However, in the illustrated example, the gripping surface 12b has a reverse tapered inner surface shape whose diameter is increased toward the distal end side in the axial direction. The inner surface shape of the gripping surface 12b corresponds to the outer surface shape of the workpiece, and in this embodiment, the gripping surface 12b is designed to grip the workpiece W having a reverse tapered outer shape toward the tip end side in the axial direction. . In addition, on the proximal end side in the axial direction of the gripping surface 12b, even when the sub collet 12 is in a released state where it is not tightened by the main collet 11, when the workpiece W is inserted into the sub collet 12, A positioning locking portion 12s is provided for contacting and locking from the base end side in the axial direction for positioning.

A sub-inclined surface 12 c that contacts the main-side inclined surface 11 c provided on the main collet 11 is formed on the outer peripheral portion of the sub-collet 12. In the illustrated example, the sub-inclined surface 12c is provided at the most distal end portion of the sub-collet 12. Further, the sub-inclined surface 12c is formed in a truncated cone-like surface having a taper angle along the axial direction, and has a reverse tapered shape in which the outer diameter increases toward the tip end side in the axial direction of the sub-collet 12. Yes. The sub-inclined surface 12c is in close contact with the main-side inclined surface 11c in a state where the workpiece W is gripped, so that the sub-inclined surface 12c has substantially the same taper angle as the main-side inclined surface 11c. It is formed.

A guided surface 12d made of a cylindrical surface having a constant inner diameter in the axial direction is formed on the inner periphery of the secondary collet 12 on the proximal end side in the axial direction with respect to the region where the secondary inclined surface 12c is formed. The Further, a sub-stepped portion 12e having a stepped surface facing the base end side in the axial direction is provided between the guided surface 12d and the sub-side inclined surface 12c. In the illustrated example, the sub-stepped portion 12e is configured in a truncated cone shape (reverse taper shape) that faces the distal end side in the axial direction and is inclined toward the outer peripheral side. In the case of the illustrated example, the guided surface 12d is in sliding contact with the guide surface 11d, whereby the sub collet 12 is guided so as to be movable in the axial direction with respect to the main collet 11. Moreover, the sub-side step part 12e is formed in the position and shape which fit the said main side step part 11e. Specifically, when the main step 11e and the sub step 12e are fitted, the sub step 12e is in close contact with the tapered step surface 11e1 of the main step 11e, but the vertical step surface 11e2. Is spaced from the surface of the sub-step 12e. Due to the engagement structure of the main side step portion 11e and the sub side step portion 12e, the sub collet 12 is retained on the tip end side in the axial direction while being accommodated in the main collet 11.

The workpiece W shown in FIG. 1 (c) having an outer surface shape corresponding to the inner surface shape of the gripping surface 12b of the sub-collet 12 has a shape extended in the axial direction and is inclined obliquely toward the proximal end side in the axial direction. An outer peripheral envelope shape Wo (indicated by an alternate long and short dash line in the figure) having a reverse tapered shape is provided. For example, as an example of the outer peripheral surface shape constituting the outer envelope shape Wo, there is a male screw structure formed around the axis. Further, a small-diameter end Wp that fits the positioning locking portion 12s is formed at the base end in the axial direction of the collet chuck. Further, an axial hole Wi is formed that opens at the opening end at the tip in the axial direction. For example, as an example of the shaft hole Wi, a hexagonal hole into which a tool such as a wrench is fitted may be mentioned.

In the collet chuck 10, when pressure is applied to the pressed surface 11 b of the main collet 11 from the base end side in the axial direction, the inner diameter of the main inclined surface 11 c is reduced, and this is the outer diameter of the auxiliary inclined surface 12 c of the sub collet 12. By reducing the inner diameter of the gripping surface 12b. Therefore, the workpiece W can be gripped inside the sub collet 12. An axial spring 13 is housed in the main collet 11 in a compressed state between the sub-collet 12 and the spring receiver 14. In the released state where the main collet 11 is not tightening the sub-collet 12 by the elastic force of the axial spring 13, the sub-collet 12 is guided by the guided surface 11d of the main collet 11 to the axis line. The secondary side stepped portion 12e is positioned and held at an initial position where it contacts (fits) the main side stepped portion 11e.

Here, the grooves 11q1 and 11q2 provided on the main inclined surface 11c are formed by the annular corners formed by providing the grooves 11q1 and 11q2 in the gripping state on the auxiliary inclined surface 12c. An axial displacement between the main inclined surface 11c and the sub inclined surface 12c is suppressed. However, these grooves 11q and 11q2 do not hinder sliding in the axial direction of the main inclined surface 11c and the sub inclined surface 12c in the released state. In the present embodiment, the grooves 11q1 and 11q2 are formed on the main inclined surface 11c, but may instead be formed on the auxiliary inclined surface 12c, and may be formed on the main inclined surface 11c and the auxiliary inclined surface 11c. You may provide in both the side inclined surfaces 12c. Moreover, in order to obtain the biting action of the corner portion, the groove may be formed so as to extend in a direction intersecting the axial direction.

Further, in the contact structure of the main step 11e and the sub step 12e, the sub step 12e is in close contact with the tapered step surface 11e1 of the main step 11e, and the vertical step surface 11e2 A gap is formed between the sub-step 12. In this way, the tapered step surface 11e1 formed on the inner peripheral side of the main step 11e is brought into contact with the sub step 12e, the sub collet 12 is positioned in the axial direction, and the vertical step formed on the outer periphery. By adopting a structure in which the step surface 11e2 is separated from the sub-side step portion 12e, the internal processing of the main collet 11 is facilitated and the surface accuracy of the tapered step surface 11e1 is easily improved. Moreover, the fluctuation | variation of the retaining position of the axial direction with respect to the main collet 11 of the sub collet 12 resulting from a deformation | transformation when the front-end | tip part of the main collet 11 and the sub collet 12 expands / contracts radially can also be suppressed. The tapered step surface 11e1 does not necessarily need to be tapered, and may be a step surface that can be in close contact with the sub-side step portion 12e in accordance with the surface shape of the sub-step portion 12e. That's fine. Further, the vertical step surface 11e2 does not necessarily need to be a vertical surface, and may be a surface separated from (not in contact with) the sub-stepped portion 12e.

4 and 5 show the structure of the chuck device 20 using the collet chuck 10 described above. However, this collet chuck 10 is slightly different from the collet chuck 10 shown in FIGS. 1 to 3, and the grooves 11q1 and 11q2 are not formed, and the step surface of the main step 11e is entirely formed. It has a surface shape that is in close contact with the sub-step 12e. Even if configured in this way, the basic operational effects are the same as described above. However, for convenience of explanation, the collet chuck shown in FIGS. 4 and 5 and each member included in the collet chuck are denoted by the same reference numerals as in FIGS.

As shown in FIG. 5, the chuck device 20 is a cap in which the collet chuck 10 is accommodated in a chuck sleeve 21 mounted on a main shaft (rear main shaft) 32 of a machine tool and attached to the chuck sleeve 21 from the front end side in the axial direction. The nut 22 is positioned on the distal end side in the axial direction, and is assembled in a state of being biased toward the distal end side by a holding spring 23 such as a coil spring from the proximal end side in the axial direction. Here, the spring receiver 24 shown in FIG. 4 is a stopper that is attached to the chuck sleeve 21 and supports the proximal end side of the holding spring 23. Note that the knockout pin 25 indicated by a two-dot chain line in FIG. 5 is inserted into the main collet 11 from the base end side in the axial direction. The knockout pin 25 always stands by on the proximal end side in the axial direction, and when the workpiece W is discharged, it is driven by a separate mechanism so as to protrude toward the distal end side in the axial direction. Eject to the tip end in the axial direction and discharge.

The chuck sleeve 21 is attached coaxially to the collet chuck 10 with respect to the main shaft 32. A longitudinal groove 21a is formed in the outer peripheral portion of the chuck sleeve 21 on the proximal end side in the axial direction. The longitudinal groove 21a is fitted to the main shaft 32 so that the chuck device 20 rotates around the axis integrally with the main shaft 32. Composed. The chuck sleeve 21 functions as an action member for expanding and contracting the main collet 11 and the sub-collet 12 of the collet chuck 10 in the radial direction. On the inner peripheral portion of the cylindrical chuck sleeve 21 on the distal end side in the axial direction, a frustoconical (reverse tapered) pressure surface 21b is formed so as to open toward the distal end side in the axial direction. . The chuck sleeve 21 is moved in the axial direction by a known drive mechanism. When the chuck sleeve 21 is in the position shown in FIG. 6A (release drive position), the tip portions of the main collet 11 and the sub-collet 12 are in a released state that spreads to the outer peripheral side. On the other hand, when the chuck sleeve 21 moves to the tip end side in the axial direction and is at the position (gripping drive position) shown in FIG. 6B, the pressing surface 21b presses the pressed surface 11b, and the main collet 11 and The secondary collet 12 can be reduced in diameter to be in a gripping state.

The cap nut 22 includes an opening 22a through which the axial end portions of the main collet 11 and the sub-collet 12 can pass, and a positioning surface 22b at the opening inner edge of the opening 22a is an outer peripheral step of the main collet 11. It is in contact with the portion 11p. The base end portion of the cap nut 22 is fixed to the main shaft 32 by a screw structure or the like. The collet chuck 10 is positioned in the axial direction by being urged toward the distal end side in the axial direction by the holding spring 23 while being in contact with the positioning surface 22 b of the cap nut 22. Further, the collet chuck 10 is positioned and fixed in the axial direction with respect to the main shaft 32 even when the chuck sleeve 21 moves in the axial direction relative to the main shaft 32 and the collet chuck 10 is opened and closed. Is done.

In FIG. 6 (a) showing the released state, the

slits

11a and 12a are drawn more open than actual in order to emphasize the expanded state of the main collet 11 and the sub-collet 12. Actually, the natural state is such that no external force is applied, and the gripping force is not generated on the workpiece W (not shown). However, even in this released state, the pressed surface 11b of the main collet 11 abuts on the pressing surface 21b of the chuck sleeve 21 as shown, or the outer periphery of the tip of the main collet 11 is the opening 22a of the cap nut 22. As a result, it is possible to prevent the collet chuck 10 from being displaced or the like. At this time, if the sub-inclined surface 12c of the sub-collet 12 is in contact with the main-side inclined surface 11c of the main collet 11, the axial displacement of the gripping surface 12b of the sub-collet 12 can be avoided as a result. Can do. This is because a defect when inserting the workpiece W into the chuck device 20 in the manufacturing method described later, that is, the workpiece W is not aligned with the tip opening of the gripping surface 12b of the sub-collet 12, and the workpiece W is aligned with the sub-collet 12. It is possible to prevent the situation where it cannot be inserted into the inside of the machine.

On the other hand, in FIG. 6B showing the gripping state, the workpiece W is inserted into the auxiliary collet 12 from the axial front end side (left side in the drawing), and the diameter of the workpiece W is reduced through the main collet 11 by the pressing force of the chuck sleeve 21. The gripping surface 12a of the secondary collet 12 grips the workpiece W. In the process of shifting from the released state to the gripping state, when the workpiece W is inserted into the sub-collet 12 in the released state shown in FIG. 6A, the workpiece W is provided on the proximal end side in the axial direction of the gripping surface 12a. When abutted against the positioning locking portion 12s, the sub collet 12 compresses the axial spring 13 and moves slightly toward the proximal end in the axial direction. At this time, since the guided surface 12d of the sub collet 12 is guided in the axial direction by the guide surface 11d of the main collet 11, the axial displacement of the sub collet 12 hardly occurs. Thereafter, as shown in FIG. 6B, the workpiece W is gripped by the gripping surface 12 b by the movement of the chuck sleeve 21. At this time, when the grooves 11q1 and 11q2 are formed as shown in FIGS. 1 to 3, the corners formed by the grooves 11q1 and 11q2 are formed between the main-side inclined surface 11c and the sub-side inclined surface 12c. As a result, the displacement in the axial direction of the sub collet 12 relative to the main collet 11 when shifting from the released state to the gripping state is reduced. The same applies to the case where the groove is provided on the sub-inclined surface 12c.

In the present embodiment, since the workpiece W is configured in a reverse taper shape that is inclined obliquely toward the proximal end side in the axial direction, the gripping surface 12b of the sub collet 12 is formed in a reverse taper shape that is inclined obliquely toward the distal end side in the axial direction. Therefore, it is easy to move to the tip side in the axial direction. Therefore, if the workpiece W is subjected to drilling or bleaching from the distal end side in the axial direction in the gripping state shown in FIG. 6B, the machining force toward the proximal end side in the axial direction is applied to the workpiece W. If the force is applied, the workpiece W may be displaced in the axial direction due to the impact caused by the fluctuation of the machining force and the gripping force applied from the reverse tapered gripping surface. Further, although different from the situation of the present embodiment, when the workpiece W is not positioned on the proximal end side in the axial direction by the positioning locking portion 12s, the gripping surface 12b or the workpiece W is reversely tapered or tapered. Regardless of whether the shape is cylindrical or cylindrical, the workpiece W may be displaced toward the proximal end in the axial direction by applying the processing force.

However, in the present embodiment, the sub-inclined surface 12c of the sub-collet 12 is formed in a reverse taper shape, and has a reverse-tapered fitting structure in contact with the reverse-tapered main-side inclined surface 11c of the main collet 11. is doing. As a result, when the processing force is applied and the workpiece W tries to move toward the base end side in the axial direction, the sub collet 12 also tends to move toward the base end side in the axial direction with respect to the main collet 11, so Since the gripping force applied to the workpiece W by the gripping surface 12b increases due to the fitting structure, the displacement of the workpiece W in the axial direction (particularly toward the tip end in the axial direction due to the reverse taper shape of the gripping surface 12b and the workpiece W). Misregistration) is suppressed. At this time, when the grooves 11q1 and 11q2 are formed as shown in FIGS. 1 to 3, the corners formed by the grooves 11q1 and 11q2 are formed between the main-side inclined surface 11c and the sub-side inclined surface 12c. As a result, the positional deviation in the axial direction of the sub collet 12 relative to the main collet 11 due to the processing force is further reduced. The same applies to the case where the groove is provided on the sub-inclined surface 12c.

Further, when the positioning locking portion 12 s is provided on the gripping surface 12 b as in the present embodiment, the workpiece W is inserted when the workpiece W is inserted into the sub-collet 12 in the released state of the chuck device 20. Is positioned on the base end side in the axial direction by abutting against the positioning locking portion 12s, and the workpiece W is gripped by the sub-collet 12 in this positioning state, so that the position accuracy of the workpiece W in the axial direction relative to the sub-collet 12 and The reproducibility can be improved. In particular, since the axial spring 13 biases the sub collet 12 toward the front end side in the axial direction with respect to the main collet 11, the positioning accuracy of the workpiece W and the sub collet 12 in the axial direction is further improved. Therefore, by making the machining reference of the workpiece W the sub collet 12, the machining accuracy in the axial direction of the workpiece W can be improved and the reproducibility of the machining shape can be improved.

7A to 7E show a method for processing the workpiece W that can effectively use the collet chuck 10 or the chuck device 20 of the present embodiment, or manufacture of a product manufactured by processing the workpiece W. It is process drawing which shows a method. The headstock 1 is equipped with a main shaft 2, and the raw material W 0 of the workpiece W is gripped by a chuck device 3 provided at the tip of the main shaft 2. The raw material W0 is, for example, a round bar, and may be a material previously formed in a predetermined length corresponding to the workpiece W, or it is assumed that a spindle moving type automatic lathe (Swiss type automatic lathe) or the like is used. The long material may be used. At this time, it is preferable to use the guide bush device 4 (shown by dotted lines) in order to increase the processing accuracy, particularly when the above long material is used.

The raw material W0 is processed by an appropriate tool 5 while being held by the main shaft 2 as shown in FIG. In the case of this embodiment, the tip of the raw material W0 is processed into a taper shape, and screw processing or the like is performed as necessary. For example, when manufacturing a dental implant material (dental implant fixture, dental implant abutment, etc.) as a product, first, a saddle shape of the outer surface of the product is formed, and then a detailed structure of the outer surface, for example, Mold external thread structure (tapping screw, etc.). The cross-sectional shape of the product workpiece W2 made of this dental implant material or the like is shown in FIG. 7 (f), and details will be described later. In many cases, since the saddle shape on the outer surface of the dental implant material has a tapered shape, the outer surface of the workpiece W0 is processed into a tapered shape as shown in FIG. 7B.

Here, as shown in FIG. 7B, the spindle 32 mounted on the back spindle stock 31 is arranged on the same axis as the spindle 2, and the chuck device 20 is arranged at a position facing the raw material W0. . As is well known, the back spindle mechanism including the spindle 32 is preferably movably provided with the spindle 2 in the machine tool. However, if the relative positional accuracy is ensured, the spindle 2 It may be provided in a device different from the device having it.

Next, as shown in FIG. 7 (c), the back spindle stock 31 is moved in the axial direction, and the tip portion of the raw material W0 held by the main shaft 2 is moved to the released chuck device shown in FIG. 6 (a). 20 are inserted into the above-mentioned secondary collets 12. Here, not the back head stock 31 but the head stock 1 may be moved, and the back head stock 31 and the head stock 1 may be moved together. When the positioning locking portion 12s is provided on the gripping surface 12b of the sub-collet 12 as described above, the distal end portion of the raw material W0 comes into contact with the positioning locking portion 12s, and FIG. As shown, the secondary collet 12 is slightly pushed toward the proximal end in the axial direction. At this time, since the secondary collet 12 is urged toward the distal end side in the axial direction by the axial spring 13, the distal end portion of the raw material W0 is maintained in contact with the positioning locking portion 12s.

On the other hand, when the positioning lock 12s is not provided in the secondary collet 12, the insertion depth of the raw material W0 with respect to the secondary collet 12 is set according to the positional relationship between the main shaft 2 and the main shaft 32. At this time, the axial position of the leading end portion of the raw material W0 in the gripping surface 12b is in the axial direction of the main shaft 2 and the main shaft 32 with reference to the initial position of the sub collet 12 positioned by the axial spring 13 in the released state. Determined by the relative spacing of. Here, as a case where the positioning locking portion 12s is not provided, for example, the gripping surface 12b has a reverse taper shape corresponding to the outer shape portion excluding the front end portion and the rear end portion of the workpiece W as in the present embodiment. Although it has an inner shape, there may be a case where it does not have a portion reflecting the shape of the small diameter end Wp of the workpiece W. In addition, when the entire workpiece W is not reversely tapered and has a cylindrical portion at least in a partial region in the axial direction, the gripping surface 12b on the cylindrical surface for gripping the cylindrical portion, It is also possible to do.

As described above, after the raw material W0 is inserted and positioned by any of the above methods, the chuck device 20 shifts to the gripping state. That is, the chuck sleeve 21 is driven in the axial direction, and the main collet 11 and the sub-collet 12 are reduced in diameter to grip the leading end portion of the raw material W0 as shown in FIG. In this state, as shown in FIG. 7C, by using a tool 6 such as a parting tool while simultaneously rotating the main shaft 2 and the rear main shaft 32, the tip portion subjected to the main surface processing from the raw material W0 is removed. Separate. The tip portion is an intermediate workpiece W1 that has been subjected to main surface processing. FIG. 7D shows a state in which the back spindle stock 32 is separated from the spindle stock 1 while the chuck device 20 of the back spindle 32 grips the intermediate work W1.

Thereafter, as shown in FIG. 7E, the back surface machining is performed on the intermediate workpiece W1 held by the chuck device 20 of the back spindle 32. There are no particular limitations on the type and mode of this back surface machining. For example, as shown in the figure, the cutting surface of the intermediate workpiece W1 is drilled with a drill or broach shown as the tool 7, or a tool engagement such as a hexagonal hole is performed. It is typical to form a structure or to perform processing toward the base end side in the axial direction. However, it is not limited to the case where machining is performed in such a manner that a machining force is directly applied to the base end side in the axial direction of the chuck device 20 as shown in the drawing, but the outer peripheral surface (from the chuck device 20) by a cutting tool or the like. Also in the turning process of the protruding portion), when the machining is performed in such a manner that the tool is sent to the base end side in the axial direction with respect to the work W1, the machining force directed toward the base end side in the axial direction is indirectly applied to the workpiece. Will join W1.

When a processing force is applied to the intermediate workpiece W1 toward the proximal end in the axial direction as described above, a force directed toward the proximal end in the axial direction is also exerted on the secondary collet 12, but the secondary collet 12 is affected by the force. Is about to move toward the proximal end in the axial direction, the gripping surface 12b of the sub-collet 12 is further reduced in diameter by the reverse tapered fitting structure of the main-side inclined surface 11c and the sub-side inclined surface 12c. As a result, the axial displacement of the intermediate workpiece W1 relative to the secondary collet 12 and the axial displacement of the secondary collet 12 itself are also suppressed. In addition, it is possible to prevent damage due to the displacement of the outer surface gripped by the gripping surface 12b of the intermediate workpiece W1. This effect is caused by the fact that the

slits

11a and 12a are formed so as to extend from the front end edge in the axial direction of the main collet 11 and the sub collet 12 toward the base end side. 11 and the sub collet 12 are further reduced in diameter by further strengthening the distal end portion than the proximal end portion in the axial direction.

In particular, in the case of the present embodiment, the outer peripheral envelope shape Wo of the intermediate workpiece W1 is formed in a reverse taper shape that is inclined obliquely toward the base end side in the axial direction, and correspondingly, the gripping surface 12b of the sub collet 12 is configured. Is formed in a reverse taper shape inclined obliquely toward the tip end side in the axial direction. Therefore, even when the positioning locking portion 12s is provided on the gripping surface 12b, the gripping state of the intermediate workpiece W1 by the gripping surface 12b of the sub-collet 12 is inherently unstable, and the tip side in the axial direction of the gripping force Due to the component toward, the intermediate workpiece W1 may be displaced toward the tip in the axial direction when receiving an impact. For the same reason, when the reverse tapered fitting structure of the main-side inclined surface 11c and the sub-side inclined surface 12c receives an impact, the auxiliary collet 12 has an axial tip with respect to the main collet 11. There is also a possibility of causing a position shift to the side. However, in the present embodiment, the gripping force exerted on the intermediate workpiece W1 by the gripping surface 12b of the sub-collet 12 increases due to the above reasons even when receiving an impact as described above. Since the tightening force also increases, it is possible to avoid the displacement of the intermediate workpiece W1 and the sub collet 12 described above. Of course, even when the positioning lock 12s is not provided on the gripping surface 12b and the intermediate workpiece W1 may be displaced toward the proximal end in the axial direction, the displacement can be suppressed.

When the collet chuck 10 shown in FIG. 1 to FIG. 3 is used, the grooves 11q1 and 11q2 of the main inclined surface 11c cause the corners formed by the grooves to be opposed to the opposing inclined surface 12c in the gripped state. Since it bites against the main collet 11, the axial displacement of the sub collet 12 with respect to the main collet 11 is further less likely to occur. The same applies to the case where the groove is provided on the sub-inclined surface 12c.

Finally, the finished workpiece W2 is discharged from the chuck 20 using the above-described knockout pin 25 or the like. As an example of the product workpiece W2, as shown in FIG. 6 (f), one constituting a dental implant can be cited. This product workpiece W2 has an outer peripheral envelope shape that is tapered in the axial direction, and an outer peripheral screw structure Ws that forms a tapping screw or the like is formed on the outer peripheral surface. Further, a proximal end in the axial direction is provided with a small-diameter end Wp having a convex curved surface shape. The outer envelope shape, the outer thread structure Ws, and the small diameter end Wp are formed by the main surface processing. Further, the length of the product workpiece W2 in the axial direction is determined by the cutting process at the time of delivery from the main spindle 2 to the rear main spindle 32. By performing this cutting process with the sub collet 12 of the chuck device 20 as a reference while being gripped by the chuck device 20 of the back main shaft 32, the length in the axial direction can be increased, and Consistency with the shape (shaft hole Wi) formed by back surface processing can be improved. Furthermore, a shaft hole Wi is formed in the product workpiece W2 so as to open to the opening end on the tip end side in the axial direction. The shaft hole Wi is formed by the back surface processing.

[Second Embodiment] Next, a second embodiment different from the collet chuck 10 will be described with reference to FIG. A collet chuck 10 'shown in FIG. 8 has a main collet 11', an axial spring 13 'and a spring receiver 14' which are basically the same as those in the first embodiment, but are arranged inside the main collet 11 '. The structure of the sub collet 12 'is different. The sub-collet 12 'of the present embodiment is similar to the above in that it includes a sub-side inclined surface 12c' that is in close contact with the main-side inclined surface 11c 'provided on the tip side in the axial direction of the main collet 11'. On the distal end side in the axial direction of the sub-collet 12 ', an engaging grip portion 12b' protruding from the outer peripheral side to the inner peripheral side is formed as a portion corresponding to the grip surface 12b. The engagement gripping portion 12b ′ protrudes to the inner peripheral side from the inner peripheral surface on the proximal end side in the axial direction of the sub-collet 12 ′. As shown in the drawing, this is a so-called jumping grasp so that the large-diameter portion Ws ′ having a large outer diameter protruding toward the outer peripheral side can grip the workpiece W ′ formed on the proximal end side in the axial direction. This is to make it possible. That is, in the sub-collet 12 ', when the workpiece W' is inserted into the inner peripheral side of the engagement gripping portion 12b ', the engagement gripping portion 12b' exceeds the large diameter portion Ws' and is on the tip end side in the axial direction. The portion of the workpiece W ′ in the can be gripped.

In this embodiment, the locking member 12t ′ is attached and fixed to the base end side in the axial direction from the engagement gripping portion 12b ′ of the sub-collet 12 ′. In the illustrated example, the locking member 12t ′ is fixed to the base end portion of the sub collet 12 ′ by screwing or the like. A positioning locking portion 12s ′ is formed at the tip of the locking member 12t ′ in the axial direction so as to contact the workpiece W ′ and perform positioning in the axial direction. The positioning locking portion 12s 'is disposed at a position spaced apart from the engagement gripping portion 12b' on the proximal end side in the axial direction so that the large diameter portion Ws 'of the workpiece W' can be accommodated. The

Inside the main collet 11 ′, a cylindrical guide member 11d ′ is attached on the proximal end side in the axial direction. Inside the guide member 11d ', a guided surface 12d' provided on the outer peripheral surface of the base end portion of the sub-collet 12 'is guided so as to be slidable in the axial direction. The auxiliary collet 12 'is housed inside the guide member 11d' and is axially distal by an axial spring 13 'supported by a spring receiver 14' attached to the axial base end of the main collet 11 '. Is biased to the side. A positioning pin 12e 'is attached to the base end portion of the sub-collet 12', and this positioning pin 12e 'is inserted into a positioning hole 11e' provided in the guide member 11d '. In the released state of the collet chuck 10 'shown in FIG. 8 (b), the positioning pin 12e' comes into contact with the tip end edge in the axial direction of the positioning hole 11e ', so that the sub-collet 12' is axial with respect to the main collet 11 '. It is positioned on the tip side in the direction and is in a state of being prevented from coming off.

When the workpiece W ′ is inserted into the released collet chuck 10 ′ shown in FIG. 8B and the workpiece W ′ is further pushed in with the workpiece W ′ in contact with the positioning locking portion 12s ′, FIG. As shown in c), the secondary collet 12 'moves toward the proximal end in the axial direction while the axial spring 13' is compressed. At this time, the secondary collet 12 'of the secondary collet 12' is guided by the primary inclined surface 11c 'of the primary collet 11', whereby the secondary collet 12 'is reduced in diameter, and the engaging gripping portion 12b' is The outer surface of the gripped portion having a small outer shape on the tip end side in the axial direction is closer to the larger diameter portion Ws ′ of the workpiece W ′. Further, when the workpiece W ′ is pushed in, the positioning pin 12e ′ comes into contact with the proximal end edge in the axial direction of the positioning hole 11e ′ and is positioned. Thereafter, when the pressurized surface 11b ′ of the main collet 11 ′ is pressurized by an action member (not shown) similar to the first embodiment, the diameter of the main collet 11 ′ is reduced and the main inclined surface 11c ′ is inclined on the sub-side. Since the surface 12c ′ is tightened, the engagement gripping portion 12b ′ of the sub collet 12 ′ grips the workpiece W ′ as shown in FIG. 8 (d).

In the present embodiment, in the gripping state shown in FIG. 8 (d), when a processing force or an impact toward the proximal end in the axial direction is applied to the workpiece W ', the sub collet 12' is applied to the main collet 11 '. On the other hand, even when trying to move to the base end side in the axial direction, the gripping force increases due to the reverse tapered fitting structure of the main inclined surface 11c ′ and the sub inclined surface 12c ′. Can be prevented, and damage to the workpiece W ′ due to the misalignment can also be avoided. In the illustrated example, in the gripping state, the positioning pin 12e ′ is in contact with the axial base end edge of the positioning hole 11e ′, and the sub-collet 12 ′ is positioned in the axial direction with respect to the main collet 11 ′. However, when the above processing force or impact is applied, the gripping force can be temporarily increased even if the auxiliary collet 12 'hardly moves in the axial direction. However, the positioning pin 12e ′ and the axial base end edge of the positioning hole 11e ′ are arranged so that the secondary collet 12 ′ can move to the base end side in the axial direction with respect to the main collet 11 ′ even in the gripping state. Alternatively, the positioning hole 11e ′ may have no opening edge on the base end side in the axial direction.

[Third Embodiment] FIG. 9 is a longitudinal sectional view showing a released state (a) and a gripped state (b) of a chuck device 20 ″ having a third embodiment of another collet chuck. This collet chuck. Is a collet chuck of an inner diameter gripping type that grips the inner diameter of the work from the inside, and has a structure in which the relationship between the inner peripheral side and the outer peripheral side is reversed from the collet chuck 10 of the first embodiment. Further, it is configured in a cylindrical shape (cylindrical shape) having a plurality of slits 11a ″ around the axis, and has an inversely tapered and tapered surface 11b ″ to be pressed on the inner periphery. The pressurized surface 11b ″ includes a tip-side pressurized surface portion having a reverse taper shape (conical truncated cone shape) formed on the distal end side in the axial direction and a tapered shape (conical truncated cone shape) formed on the proximal end side in the axial direction. ) Of the base end-side pressed surface, and is pressed by pressure surfaces 21a "and 22a" of the action member, which will be described later. A tapered (conical frustum-shaped) main-side inclined surface 11c ″ is formed obliquely toward the distal end side in the direction. The collet chuck in the illustrated example is formed from the distal end edge in the axial direction and extends toward the proximal end side. Although it has a split collet structure in which slits 11a ″ that extend and slits 11a ″ (not shown) that are formed from the base edge in the axial direction and extend toward the distal end are alternately formed as seen around the axis, Formed from the leading edge of the direction and extending to the proximal side It may have a single split collet structure having only split Ri.

In the chuck device 20 ″ of the present embodiment, as an action member for driving the main collet 11 ″, a pressure surface 21a ″ having a reverse taper shape (conical truncated cone shape) obliquely directed toward the base end side in the axial direction is provided. In addition, a first action member 21 ″ having a slide shaft portion 21b ″ extending toward the base end side in the axial direction and a slide shaft portion 21b ″ of the first action member 21 ″ are movably inserted in the axial direction. A cylindrical (cylindrical) member having a tapered (conical frustum) pressure surface 22a ″ obliquely directed to the distal end side in the axial direction, and a cylindrical surface having the same diameter on the proximal end side in the axial direction And a second action member 22 ″ having a guide surface 22b ″. Here, the second action member 22 "is fixed to a main shaft (not shown), and the position of the first action member 21" can be changed back and forth by a drive mechanism (not shown).

In the present embodiment, a cylindrical (cylindrical) sub-collet 12 ″ is disposed on the outer peripheral side of the main collet 11 ″. The sub-collet 12 ″ has a plurality of slits 12a ″ formed from the front end edge in the axial direction and extending toward the proximal end around the axis. Further, on the inner periphery of the sub-collet 12 ″, a sub-inclined surface 12c ″ that is in close contact with the main-side inclined surface 11c ″ provided on the outer periphery of the main collet 11 ″ is inclined toward the front end side in the axial direction. It is formed as a surface (conical frustum shape). On the base end side in the axial direction of the sub-collet 12 ″, a base end portion extending in a cylindrical shape is formed in a region where the slit 12a ″ is not formed, and the inner surface of the base end portion is shown in FIG. 9 (a). Thus, it is a guided surface 12d "guided by the guide surface 22b" of the second acting member 22 ". Further, the base end portion of the sub-collet 12" has an axial direction of the main collet 11 ". A step surface 12e ″ that engages with an end surface 11e ″ provided at the base end of the main collet 12 ″ is provided, and the sub-collet 12 ″ is axially oriented with respect to the main collet 11 ″ by contact between the end surface 11e ″ and the step surface 12e ″. The sub-collet 12 ″ is biased toward the distal end side in the axial direction by an axial spring 13 ″ disposed on the proximal end side in the axial direction.

In the present embodiment, the gripping surface 12b ″ provided on the outer periphery of the sub-collet 12 ″ is formed in accordance with the shape of the inner diameter portion of the work W ″. In the illustrated example, the gripping surface 12b ″ is drawn as a simple cylindrical surface. It is. However, depending on the shape of the inner periphery of the workpiece W ″, for example, the gripping surface 12b ″ may be formed on a tapered (conical frustum) surface that is inclined obliquely toward the tip end in the axial direction. If it does in this way, the effect similar to 1st Embodiment which has the said holding surface 12b will be acquired. On the proximal end side in the axial direction of the gripping surface 12b ", there is provided a positioning locking portion 12s" formed as a stepped surface projecting outward from the gripping surface 12b ". The positioning locking portion 12s" When W ″ is mounted from the front end side in the axial direction to the outer peripheral side of the sub-collet 12 ″, it comes into contact with the edge of the work W ″ and positions the work W ″ in the axial direction.

In the present embodiment, the workpiece W ″ is mounted on the outer periphery of the sub-collet 12 ″ from the tip end side in the axial direction in the released state shown in FIG. 9 (a). At this time, the work W ″ is brought into contact with the positioning locking portion 12 s ″ as necessary. At this time, the sub-collet 12 ″ is compressed against the main collet 11 ″ by the axial spring 13 ″ and is axially moved. Then, when the first working member 21 ″ is moved to the proximal side in the axial direction with respect to the second working member 22 ″, the surface 11b ″ to be pressed of the main collet 11 ″. Is pressed against the pressurizing surfaces 21a "and 22a", the diameter of the main collet 11 "is increased, and the main-side inclined surface 11c" of the main collet 11 "expands the auxiliary-side inclined surface 12c" to thereby expand the auxiliary collet. The diameter is increased by 12 ″. As a result, as shown in FIG. 9B, the gripping surface 12b ″ of the sub collet 12 ″ grips the inner diameter of the workpiece W ″ from the inside.

In the present embodiment, in the gripping state of the chuck device 20 ″, when a machining force or an impact is applied to the workpiece W ″ from the front end side in the axial direction, the sub collet 12 ″ moves in the axial direction with respect to the main collet 11 ″. Although it tends to move to the base end side, the gripping force of the gripping surface 12b ″ of the sub-collet 12 ″ on the workpiece W ″ increases due to the tapered fitting structure of the main-side inclined surface 11c ″ and the sub-side inclined surface 12c ″. Therefore, the displacement of the workpiece W ″ and the sub collet 12 ″ in the axial direction is prevented, and damage to the workpiece W ″ due to the displacement is also suppressed.

As shown by a two-dot chain line in FIG. 9B, a cylindrical extension portion extending toward the base end side in the axial direction is formed in the main collet 11 ″, and an outer peripheral surface of the extension portion is defined as a guide surface 11d ″. The guided surface 12d ″ of the sub-collet 12 ″ may be guided along the guide surface 11d ″ in the axial direction. At this time, the base end surface of the extension is used as the main side step portion 11e ″. The main side step portion 11e ″ abuts on the sub side step portion 12e ″ of the sub collet 12 ″ so that the sub collet 12 ″ is positioned in the axial direction with respect to the main collet 11 ″ so as to be prevented from coming off. It may be.

The manufacturing method of the collet chuck, the chuck device, and the processed product according to the present invention is not limited to the illustrated examples described above, and various changes can be made without departing from the scope of the present invention. For example, the anti-slip structure of the grooves 11q1 and 11q2 shown in FIGS. 1 to 3 of the first embodiment and the anti-slip structure of the main side step portion 11e and the sub side step portion 12e may be used in the second embodiment. The above-described anti-slip structure may be used for a corresponding part in the third embodiment.

DESCRIPTION OF SYMBOLS 10 ... Collet chuck, 11 ... Main collet, 11a ... Slot, 11b ... Pressurized surface, 11c ... Main side inclined surface, 11d ... Guide surface, 11e ... Main side step, 12 ... Sub collet, 12a ... Slot, 12b ... Gripping surface, 12c ... Secondary inclined surface, 12d ... Guided surface, 12e ... Secondary side step, 13 ... Axial spring, 14 ... Spring receiver, 20 ... Chuck device, 21 ... Sleeve, 21b ... Pressure surface, 22 ... Cap nut, 23 ... Holding spring, 24 ... Spring receiver, 31 ... (Back) headstock, 32 ... (Back) spindle, W ... Workpiece

Claims

A cylindrical main collet, and a cylindrical sub-collet arranged on the inner peripheral side of the main collet so as to be movable in the axial direction with respect to the main collet,
The main collet is a plurality of slits extending in the axial direction, a surface provided on the outer periphery and pressed to expand and contract the inner diameter of the main collet, and is tapered toward either side in the axial direction. A pressure-receiving surface configured in a shape or a reverse taper shape, and a main side inclined surface configured in a reverse taper shape provided on the inner periphery and obliquely directed to the tip end side in the axial direction,
The sub-collet is configured in a plurality of slits extending in the axial direction, a gripping surface provided on the inner periphery for gripping a gripped material, and an inversely tapered shape provided on the outer periphery and in contact with the main inclined surface A collet chuck having a secondary inclined surface.
A cylindrical main collet, and a cylindrical sub-collet arranged on the outer peripheral side of the main collet so as to be movable in the axial direction with respect to the main collet,
The main collet is a plurality of slits extending in the axial direction and a surface provided on the inner periphery and pressed to expand and contract the outer diameter, and is tapered toward either side in the axial direction or A pressure-receiving surface configured in an inversely tapered shape, and a main-side inclined surface configured in a tapered shape that is provided on the outer periphery and is inclined obliquely toward the distal end side in the axial direction.
The sub-collet is configured in a plurality of slits extending in the axial direction, a gripping surface provided on the outer periphery for gripping a material to be gripped, and a tapered shape provided on the inner periphery and in contact with the main inclined surface. And a collet chuck having a secondary inclined surface.
The collet chuck according to claim 1 or 2, further comprising an axial spring that biases the sub-collet toward the distal end in the axial direction with respect to the main collet.
The said sub collet has the positioning latching | locking part which latches and positions the said to-be-gripped material from the base end side of an axial direction, when it is in a releasing state. The collet chuck described.
The collet chuck according to any one of claims 1 to 4, wherein the gripping surface of the sub-collet is a frustum-shaped surface inclined obliquely toward the tip end side in the axial direction.
The said main collet is provided with the guide surface extended in an axial direction, The said sub collet is provided with the to-be-guided surface slidably contacted with the said guide surface and guided in an axial direction. The collet chuck described in 1.
The slot of the main collet and the slot of the sub-collet are formed so as to extend from the distal end edge in the axial direction toward the base end side, and the guide surface is in the axial direction with respect to the main inclined surface. The guide surface is formed in a region disposed on the proximal side in the axial direction with respect to the sub-inclined surface. The collet chuck described.
The main collet is provided with a main side step, the sub collet is provided with a sub side step that engages with the main side step in the axial direction, and the sub side step is the main side step. The collet chuck according to any one of claims 1 to 7, wherein the sub collet is prevented from coming off toward the tip end side in the axial direction with respect to the main collet by abutting on a portion.
The groove | channel of the direction which cross | intersects an axial direction is formed in at least any one surface of the said main side inclined surface of the said main collet, and the said auxiliary side inclined surface of the said sub collet, The 1st thru | or 8 characterized by the above-mentioned. The collet chuck according to any one of the above.
A collet chuck according to any one of claims 1 to 9, and an action member configured to be movable in the axial direction and pressurizing the main collet in the axial direction to expand and contract in the radial direction. A chuck device characterized by the above.
A method of manufacturing a processed product that forms the processed product by processing the workpiece in a state where the workpiece is held by a chuck device,
The chuck device includes a collet chuck according to any one of claims 1 to 9, an action member configured to be movable in an axial direction and pressurizing the main collet in the axial direction to expand and contract in a radial direction. , And
By placing the action member in the release drive position, the main collet and the sub-collet are released, the workpiece is mounted on the sub-collet, and then the action member is placed in the grip drive position. A method for manufacturing a processed product, wherein the main collet and the sub-collet are held and the workpiece is processed.
The secondary collet is held against the main collet by being prevented from coming off on the axial front end side, and the chuck device is an axis that urges the secondary collet toward the axial front end side with respect to the main collet. The method for manufacturing a processed product according to claim 11, further comprising a directional spring.
The sub-collet has a positioning locking portion that locks and positions the workpiece from the base end side in the axial direction when in the released state, and the workpiece is mounted on the sub-collet. 13. The method for manufacturing a processed product according to claim 11, wherein the workpiece is gripped by the sub-collet while being abutted against the positioning locking portion.