JP2023141405A - Pull-in type chuck - Google Patents

Abstract

To provide a pull-in type chuck capable of strengthening gripping force on a workpiece by preventing displacement of a master jaw.SOLUTION: In a pull-in type chuck, when a plunger 20 is moved backward, respective master jaws 30 are guided by an inclined guide hole α2 and a plurality of jaws 40 approach to each other, thus placing the chuck in a chucked state in which a workpiece W arranged between the plurality of jaws 40 is gripped, and when the plunger 20 is moved forward, the respective master jaws 30 are guided by the inclined guide hole α2 and the plurality of jaws 40 separate from each other, thus placing the chuck in a non-chucked state in which gripping of the workpiece W is released. A back-up part α3 that abuts from outward to a rear end part of the master jaw 30 in the chucked state is provided on the inner peripheral side of a peripheral wall part 12 of a body 10.SELECTED DRAWING: Figure 3

Description

The present invention relates to a retractable chuck used for gripping a workpiece in a processing device such as a lathe.

2. Description of the Related Art In processing devices such as lathes, a workpiece to be processed is held by a chuck. FIG. 2 of Patent Document 1 discloses a retractable chuck in which a shaft 5 (master jaw) and a plunger 4 are assembled to a chuck main body 1 (body). The master jaw 5 is inserted into an inclined guide hole formed in the front wall of the body 1. A claw 6 (jaw) for chucking the work W is attached to the front end of the master jaw 5, and a rear end of the master jaw 5 is engaged with the plunger 4. As shown in FIG. 5 of the same document, a plurality of sets of master jaws 5 and jaws 6 are provided and arranged rotationally symmetrically with respect to the body 1.

In the retractable chuck of Patent Document 1, when the plunger 4 is moved backward (to the side opposite to the workpiece W) from the state shown in FIG. 3 of the same document, each master jaw 5 is guided by the inclined guide hole. As a result, the plurality of jaws 6 approach each other, resulting in a chucked state in which the workpiece W is gripped, as shown in FIG. 4 of the same document. On the other hand, when the plunger 4 is moved forward (toward the workpiece W side) from the state shown in FIG. Then, as shown in FIG. 3 of the same document, the workpiece W is released from being gripped and becomes a non-chucked state.

JP2015-066655A

In the retractable chuck having the above structure, the force for gripping the workpiece can be increased by increasing the force for retracting the plunger. However, as shown in FIG. 1 of this application, the plunger 20 is When the master jaw 30 is moved to a chuck state, depending on the conditions, there is a possibility that the rear end portion of the master jaw 30 may bend outward using the point _P1 as a fulcrum (see the broken line in the figure). Therefore, there is a problem in that the retracting force _F1 transmitted from the plunger 20 to the master jaw 30 is consumed by the displacement of the master jaw 30, and the increase in the gripping force _F2 of the workpiece W is restricted. Further, there is also the problem that it is difficult to ensure a wide stroke range (stroke range of the plunger 6) in which the workpiece W can be appropriately gripped.

In this regard, even in the retractable chuck of Patent Document 1, if the master jaw 6 is made thicker, the master jaw 6 can be made difficult to displace. However, in this case, the size and weight of the retractable chuck will increase. In lathes, etc., the workpiece W is rotated by rotating the retractable chuck, but as the weight of the retractable chuck increases, the centrifugal force acting on the retractable chuck increases, and the loss of gripping force due to the centrifugal force increases. growing. This makes it difficult to rotate the retractable chuck at high speed.

The present invention has been made to solve the above problems, and provides a retractable chuck that can prevent displacement of the master jaw and increase the gripping force of a workpiece. Another object of the present invention is to provide a retractable chuck that can secure a wide stroke range in which a workpiece can be appropriately gripped. Furthermore, it is also an object of the present invention to realize such a retractable chuck without increasing the size or weight of the device.

The above issues are
A body having a front wall portion in which a plurality of inclined guide holes are formed, and a peripheral wall portion surrounding a space behind the front wall portion (hereinafter referred to as a “cavity portion”);
A plunger arranged in the cavity of the body so as to be movable in the front and rear direction;
a master jaw inserted into each inclined guide hole and having its rear end engaged with the plunger;
a jaw attached to the front end of each master jaw;
When the plunger is moved backward, each master jaw is guided by the inclined guide hole, and as the plurality of jaws approach each other, the workpiece placed between the plurality of jaws is in a chucked state.
When the plunger is moved forward, each of the master jaws is guided by an inclined guide hole, and the plurality of jaws separate from each other, thereby releasing the grip on the workpiece into a non-chucked state, the retractable chuck,
The problem is solved by providing a retractable chuck characterized in that a backup part that contacts the rear end of the master jaw from the outside when in the chuck state is provided on the inner peripheral side of the peripheral wall of the body. be done.

In the retractable chuck of the present invention, the rear end portion of the master jaw in the chucked state is supported from the outside by the backup portion. For this reason, the rear end of the master jaw is prevented from bending outward when in the chuck state, so that most of the retraction force transmitted from the plunger to the master jaw is exerted for gripping the workpiece. Can be done. Therefore, it is possible to increase the gripping force of the workpiece without increasing the thickness of the master jaw. Further, it is also possible to secure a wide stroke range in which the workpiece can be appropriately gripped. In addition, the weight of the retractable chuck can be reduced by reducing its size, so that when the retractable chuck is used in a lathe or the like, it becomes possible to rotate the retractable chuck at high speed.

In the retractable chuck of the present invention, it is preferable that a seal ring for sealing the gap between the inclined guide hole and the outer circumferential surface of the master jaw is attached to the outer circumference of the master jaw. This is because if chips from the workpiece, cutting water, etc. enter the body through the gap, there is a risk of problems such as the retractable chuck not working properly, but the gap is sealed. This is because the occurrence of such problems can be suppressed.

However, if a seal ring is attached to the outer periphery of the master jaw, when assembling the master jaw to the body (when inserting the master jaw from the rear end of the inclined guide hole), the seal ring will be attached to the body. There is a risk of getting caught and getting scratched or cut. For this reason, it is preferable to provide a recessed portion for allowing the seal ring to escape when inserting the master jaw in a region between the inclined guide hole and the backup portion on the inner peripheral side of the peripheral wall portion of the body. This makes it possible to prevent the seal ring from getting caught on the body (particularly on the inner surface of the peripheral wall of the body, located behind the inclined guide hole) when the master jaw is inserted.

However, in the retractable chuck of the present invention, since the backup part is provided on the inner peripheral side of the peripheral wall of the body, even if the retractable part is provided in the area between the inclined guide hole and the backup part as described above, When assembling the master jaw to the body (when inserting the master jaw from the rear end of the inclined guide hole), the seal ring overlaps the backup part until it reaches the area where the slotted part is provided. There is a risk that the seal ring may get caught around the backup part. For this reason, a notch is provided on the outer periphery of the front end of the master jaw, and the notch allows the seal ring to overlap the backup part when the master jaw is inserted (while the front end of the master jaw is inserted into the inclined guide hole). Preferably, the structure is such that the master jaw can be moved to the opposite side of the backup portion inside the inclined guide hole. This makes it possible to prevent the seal ring from getting caught around the backup portion.

In the retractable chuck of the present invention, the manner of engagement between the master jaw and the plunger is not particularly limited. However, if the area around the engaging part of the master jaw or plunger has a complicated structure, it will be difficult to increase the rigidity of the area around the engaging part of the master jaw, etc., and there is a risk that that part will be easily displaced. For this reason, it is preferable that the area around the engaging portion of the master jaw etc. has a structure as simple as possible. Specifically, an engaging protrusion is provided on the outer periphery of the plunger, and an engaging recess is provided on the outer periphery of the rear end of the master jaw on the side opposite to the backup part, and the engaging protrusion is engaged. Preferably, the master jaw engages the plunger by fitting into the recess.

As described above, the present invention makes it possible to provide a retractable chuck that can prevent displacement of the master jaw and increase the gripping force of the workpiece. Further, it is also possible to provide a retractable chuck that can secure a wide stroke range in which a workpiece can be appropriately gripped. Furthermore, it becomes possible to realize such a retractable chuck without increasing the size or weight of the device.

FIG. 2 is a schematic cross-sectional view taken along a plane including the center line _L1 , showing how the master jaw is displaced when the conventional retractable chuck is in the chucked state. FIG. 2 is a cross-sectional view taken along a plane including the center line _L1 when the retractable chuck of the present embodiment is in a non-chucked state. FIG. 2 is a sectional view taken along a plane including the center line _L1 when the retractable chuck of the present embodiment is in the chucked state. FIG. 3 is a diagram showing the state in which the master jaw is inserted into the inclined guide hole of the body of the retractable chuck of the present embodiment, and the center line L _{1 is a cross-sectional view taken along a plane including 1.} FIG. FIG. 3 is a diagram showing how the master jaw is inserted into the inclined guide hole of the body in the retractable chuck of the present embodiment, and the seal ring on the outer periphery of the master jaw is located at the boundary between the first region and the second region. FIG. 3 is a cross-sectional view taken along a plane including the center line L ₁ when located at . FIG. 3 is a diagram showing the master jaw being inserted into the inclined guide hole of the body in the retractable chuck of the present embodiment, and the seal ring on the outer periphery of the master jaw is located at the boundary between the second region and the third region. FIG. 3 is a cross-sectional view taken along a plane including the center line L ₁ when located at . FIG. 3 is a diagram showing how the master jaw is inserted into the inclined guide hole of the body of the retractable chuck according to the present embodiment, and the seal ring on the outer periphery of the master jaw is in the third region when the center line L _{1 is a cross-sectional view taken along a plane including 1.} FIG. FIG. 2 is a cross-sectional view taken along a plane including the center line _L1 , showing how the master jaw is displaced when the retractable chuck of the present embodiment is in the chucked state. FIG. 3 is a diagram showing the vicinity of the front end of the master jaw (without a notch) in the retractable chuck. FIG. 3 is a diagram showing the vicinity of the front end of the master jaw (with a notch) in the retractable chuck.

A preferred embodiment of the retractable chuck of the present invention will be described in more detail with reference to the drawings. 2 and 3 are cross-sectional views of the retractable chuck of this embodiment taken along a plane including the center line _L1 . FIG. 2 shows the retractable chuck in a non-chuck state (the workpiece W is not gripped), and FIG. 3 shows the retractable chuck in the chuck state (the workpiece W is gripped). It shows the time. In the following, for convenience of explanation, the upper side of each drawing (the side on which the workpiece W is arranged) is referred to as the "front" side, and the lower side of each drawing (the side opposite to the side on which the workpiece W is arranged) is referred to as the "front" side. It is explained as "back" side.

The retractable chuck of this embodiment is used to grip a workpiece in a processing device such as a lathe. As shown in FIG. 2, this retractable chuck includes a body 10, a plunger 20, a master jaw 30, and a jaw 40. In each figure including FIG. 2, only one set of master jaws 30 and jaws 40 is depicted, but in reality, a plurality of sets are arranged so as to surround the workpiece W. In this embodiment, three sets of master jaws 30 and jaws 40 are arranged rotationally symmetrically around the center line _L1 . The workpiece W is gripped by the jaws 40 at its outer periphery.

The body 10 is used for assembling the various parts constituting the retractable chuck. The body 10 includes a front wall 11 on the workpiece W side, a peripheral wall 12 that surrounds a space (cavity α ₁ ) behind the front wall 11, and a rear wall 13 that covers the rear of the peripheral wall 11. has been done. A locator 70 for positioning the workpiece W in the direction along the center line _L1 is disposed further on the front side of the front wall portion 11. An inclined guide hole α ₂ is formed in the front wall portion 11 . This inclined guide hole α ₂ penetrates in a direction inclined with respect to the center line L ₁ . The inclined guide hole _α2 is for guiding the master jaw 30. Therefore, like the master jaw 30, the inclined guide holes _α2 are provided at a plurality of locations. In the body 10, the front wall part 11 and the peripheral wall part 12 are integrally formed, but the rear wall part 13 is detachably attached to the peripheral wall part 12. When assembling parts such as the plunger 20 to the body 10, the rear wall portion 13 is removed. This rear wall portion 13 is also called a "rear body."

The plunger 20 is disposed in the cavity α ₁ of the body 10 so as to be movable in the front-rear direction (direction parallel to the center line L ₁ ). The rear end side of the plunger 20 is connected to plunger driving means (not shown) for moving the plunger 20 in the front-back direction. In this embodiment, a drawbar (not shown) is used as the plunger driving means, and by screwing the rear end side (threaded part) of the draw screw 50 attached to the plunger 20 to the drawbar, the drawbar can be moved. The driving force is transmitted to the plunger 20. An engagement protrusion 21 is formed on the outer circumference of the plunger 20 to engage with the rear end of the master jaw 30. The engaging protrusions 21 are provided at locations corresponding to the respective master jaws 30 (in this embodiment, three locations rotationally symmetrical about the center line _L1 ).

The master jaw 30 is for transmitting the driving force transmitted from the drawbar (plunger driving means) to the plunger 20 to the jaw 40. An attachment recess 32 is provided on the inward surface (the surface facing the center line _L1 ) at the front end of each master jaw 30. A jaw 40 is attached to this attachment recess 32 so as to protrude inward (toward the center line _L1 ). As already mentioned, a plurality of master jaws 30 and jaws 40 are arranged, and these master jaws 30 are each inserted into the inclined guide hole _α2 of the body 10.

The master jaw 30 is normally inserted into the inclined guide hole α ₂ from the rear end side (the cavity α ₁ side) of the inclined guide hole α ₂ , as shown in FIGS. 4 to 7. This is because the above-mentioned mounting recess 32 is formed in the front end of the master jaw 30, and the front end of the master jaw 30 has a smaller cross-sectional area than the rear end. This is because it is easier to insert the master jaw 30 from the lower end side of ₂ . 4 to 7 are cross-sectional views taken along a plane including the center line _L1 , showing how the master jaw 30 is inserted into the inclined guide hole _α2 of the body 10 in the retractable chuck of this embodiment. 4 shows a case where the seal ring 60, which will be described later, is in the first region β ₁ , and FIG. 5 shows a case where the seal ring 60 is in the boundary between the first region β ₁ and the second region β ₂ . 6 shows the seal ring 60 at the boundary between the second region β ₂ and the third region β ₃ , and FIG. 7 shows the seal ring 60 at the third region β ₃ .

Further, in this embodiment, a seal ring 60 is attached to the outer peripheral portion of the master jaw 30. This seal ring 60 is fitted into a groove formed annularly along the outer periphery of the master jaw 30. This seal ring 60 seals the gap between the inner peripheral surface of the inclined guide hole α ₂ and the outer peripheral surface of the master jaw 30. Therefore, chips from the workpiece W, cutting water, etc. are difficult to enter into the body 10 through the gap.

Furthermore, an engagement recess 31 is provided at the rear end of each master jaw 30. The engagement protrusion 21 of the plunger 20 is engaged with the engagement recess 31 . In this embodiment, after assembling the master jaw 30 to the body 10 and inserting the plunger 20 into the cavity _α1 , the plunger 20 is engaged by twisting around the center line _L1 . The mating convex portion 21 is engaged with the mating concave portion 31. At the engagement portion between the engagement convex portion 21 and the engagement recess 31, movement of the master jaw 30 in the longitudinal direction (direction parallel to the center line _L1 ) with respect to the plunger 20 is restricted. On the other hand, the movement of the master jaw 30 in the lateral direction (direction perpendicular to the center line _L1 ) with respect to the plunger 20 is not particularly restricted.

Therefore, when the plunger driving means is driven from the non-chucked state shown in FIG. 2 to move the plunger 20 backward (pull the plunger 20 backward) as shown in FIG. 20, the master jaw 30 also moves rearward within the inclined guide hole _α2 . The inclined guide hole α ₂ is inclined with respect to the center line L ₁ so that the rear end thereof is closer to the center line L ₁ than the front end thereof. Therefore, as the master jaw 30 moves backward in the inclined guide hole _α2 , it moves inward (to the side approaching the center line _L1 ). At this time, the jaws 40 also move inward, and the workpiece W is held in the chuck state by the jaws 40. In the chucked state, the engagement convex portion 21 engages deeply with the engagement recess 31.

On the other hand, when the plunger 20 is moved forward (pushing the plunger 20 forward) from the chucked state shown in FIG. Move forward within α ₂ . Since the inclined guide hole α ₂ is inclined as described above, the master jaw 30 moves outward (to the side away from the center line L ₁ ) as it moves forward in the inclined guide hole α ₂ . . At this time, the jaws 40 also move outward, and the grip of the work W by the jaws 40 is released, resulting in a non-chucking state. In the non-chuck state, the engagement convex portion 21 engages shallowly with the engagement recess 31.

In this way, in the retractable chuck, when the plunger 20 pulls the master jaw 30 backward, it enters the chuck state (Fig. 3), and when the plunger 20 pushes the master jaw 30 forward, it enters the non-chuck state (Fig. 3). 2) In the conventional retractable chuck, as shown in FIG. 1, when the chuck is in the chuck state, the rear end of the master jaw 30 bends outward about point _P1 , so that the workpiece W is There was a problem in that it was difficult to increase the gripping force. In this regard, in the retractable chuck according to the present invention, as shown in _FIG . A backup portion α ₃ is provided on the inner peripheral side of the peripheral wall portion 12 of the body 10.

Therefore, as shown in FIG. 8, by supporting the rear end of the master jaw 30 in the chucked state from the outside by the backup part α ₃ , bending of the rear end of the master jaw 30 can be suppressed. I can do it. FIG. 8 is a cross-sectional view taken along a plane including the center line _L1 , showing how the master jaw 30 is displaced (almost not displaced) when the retractable chuck of this embodiment is in the chucked state. The broken line portion in FIG. 8 represents the bending of the rear end portion of the master jaw 30 that would be expected if the backup portion _α3 did not exist. Therefore, most of the retraction force _F1 transmitted from the plunger 20 to the master jaw 30 is exerted to grip the workpiece W. Therefore, it is possible to increase the gripping force _F2 of the workpiece W without increasing the thickness of the master jaw 30. Further, it is also possible to ensure a wide stroke range (stroke range in the front-rear direction of the plunger 20) in which the workpiece W can be appropriately gripped. In addition, the size of the retractable chuck can be reduced to reduce weight, allowing the retractable chuck to rotate at high speeds.

Further, in this embodiment, the support portion 14 is provided at a location on the body 10 located outside the front end portion of the master jaw 30. When the jaws 40 grip the workpiece W, a reaction force (reaction force of the gripping force _F2 ) is applied from the workpiece W to the jaws 30, and the front end of the master jaw 30 may warp outward due to the reaction force. This support portion 14 allows the front end portion of the master jaw 30 to be supported from the outside, thereby suppressing warping of the master jaw 30. The support portion 14 is provided so as to protrude forward from the front wall portion 11 of the body 10.

By the way, when the seal ring 60 is attached to the outer circumference of the master jaw 30 as described above, when the master jaw 30 is inserted from the rear end side of the inclined guide hole α ₂ , as shown in FIGS. There is a risk that the seal ring 60 may get caught on the body 10 and be damaged or cut. Additionally, there is a risk that the seal ring 60 may fall out of the groove on the outer periphery of the master jaw 30. For this reason, in this embodiment, the body 10 is provided with a slotted portion _α4 for letting the seal ring 60 escape. This padded portion α ₄ is provided in a region between the inclined guide hole α ₂ and the backup portion α ₃ (second region β ₂ in FIGS. 4 to 7) on the inner peripheral side of the peripheral wall portion 12 of the body 10. . Thereby, when the seal ring 60 moves in the second region β ₂ , the seal ring 60 can escape to the slotted portion α ₄ . Therefore, it is possible to prevent the seal ring 60 from being damaged or falling off.

However, as described above, if the backup part α ₃ is provided on the inner peripheral side of the peripheral wall part 12 of the body 10, the hollow part α ₄ is provided in the area between the inclined guide hole α ₂ and the backup part α ₃ . Even if this happens, there is a risk that the seal ring 60 may get caught around the backup portion _α3 . Therefore, in this embodiment, as shown in FIG. 4, while the seal ring 60 overlaps the backup portion α ₃ (when the seal ring 60 moves in the first region β ₁ ), the inclined guide hole α ₂ is Inside, the master jaw 30 can be moved to the side opposite to the backup part _α3 (closer to the center line _L1 ). Looking at FIG. 4, it can be seen that the center line _L3 of the master jaw 30 is closer to the inside (closer to the center line _L1 ) than the center line _L2 of the inclined guide hole _α2 . Therefore, the seal ring 60 can be moved in the first region _β1 without hitting the backup portion _α3 .

Specifically, it is done as follows. That is, as already mentioned, the front end of the master jaw 30 is provided with the mounting recess 32 for mounting the jaw 40, but in the conventional retractable chuck, the front end of the master jaw 30 is As shown in 9(a), it has the shape of a cylinder with a part cut out, and its horizontal cross section (cross section cut along a plane perpendicular to the center line _L1 (Fig. 1)) is partially cut out. It has an oval shape. As shown in FIG. 9(b), the elliptical portion occupies more than half of the area in the cross section of the inclined guide hole _α2 , so the front end of the master jaw 30 has the mounting recess 32. First, there is a state in which there is almost no play within the inclined guide hole α ₂ (a state in which it is almost impossible to move in the horizontal direction within the inclined guide hole α ₂ ). FIG. 9 is a diagram showing the vicinity of the front end of the master jaw 30 (without a notch) in the retractable chuck.

In this regard, in this embodiment, as shown in FIG. 10(a), a notch _α5 is provided on the outer peripheral portion of the front end side of the master jaw 30. A pair of notches α ₅ are provided on both sides of the mounting recess 32 . Therefore, as shown in FIG. 10(b), when the front end of the master jaw 30 is inserted into the inclined guide hole _α2 , the front end of the master jaw 30 cannot be moved horizontally within the inclined guide hole _α2 . is possible. Therefore, as shown in FIG. 4, when inserting the front end of the master jaw 30 into the inclined guide hole α ₂ , the seal ring 60 should overlap the first region β ₁ where the backup portion α ₃ exists. , the master jaw 30 can be moved toward the center line _L1 side of the retractable chuck (to the right side of the paper in FIG. 4), and the seal ring 60 can be prevented from hitting the backup portion _α3 . FIG. 10 is a diagram showing the vicinity of the front end of the master jaw 30 (with a notch α ₅ ) in the retractable chuck.

When the master jaw 30 is further inserted into the inclined guide hole _α2 from the state shown in FIG. 4, as shown in FIG. It will be in the state of ₂ . After this state is reached, unless the master jaw 30 is returned to the peripheral wall 12 side of the body 10 from the state where it is closer to the center line _L1 side of the retractable chuck, it will no longer be inserted into the inclined guide hole _α2 . I can't. For this reason, in FIG. 5, the center line _L3 of the master jaw 30 is made to coincide with the center line of the inclined guide hole _α2 . At this time, as shown in FIG. 5, the seal ring 60 is in a state closer to the peripheral wall portion 12 side of the body 10, but the seal ring 60 has reached the second region β ₂ where the hollow portion α ₄ is provided. There is. Therefore, when the seal ring 60 is in the second region _β2 , the seal ring 60 can be released at the slotted portion _α4 .

Thereafter, as shown in FIG. 6, when the seal ring 60 reaches the lower end of the inclined guide hole α ₂ (the boundary between the second region β ₂ and the third region β ₃ ), the seal ring 60 is tilted. Since the force is applied substantially uniformly from the inner circumference of the guide hole _α2 , the master jaw 30 can be inserted smoothly without applying any local force to the seal ring 60 (FIG. 7). After inserting the master jaw 30 into the inclined guide hole _α2 , the jaw 40 (FIG. 2) is attached to the front end of the master jaw 30, and the plunger 20 (FIG. 2) is inserted into the cavity _α1 of the body 10. Then, the engaging convex portion 21 is engaged with the engaging concave portion 22. Thereafter, the rear side of the body 10 is covered with the rear wall portion 13 (rear body), and the assembly of the retractable chuck is completed.

The retractable chuck according to the present invention described above can be used in various applications where it is necessary to grip a workpiece W. Among these, it can be suitably employed in a workpiece processing device that processes the workpiece W, and can be particularly suitably employed in a lathe that performs cutting while rotating the workpiece W.

10 Body 11 Front wall 12 Peripheral wall 20 Plunger 21 Engagement protrusion 30 Master jaw 31 Engagement recess 40 Jaw 60 Seal ring α ₁ Cavity α ₂ Inclined guide hole α ₃ Backup part α ₄ Snotted part α ₅ Notch W work

Claims (4)

A body having a front wall portion in which a plurality of inclined guide holes are formed, and a peripheral wall portion surrounding a space behind the front wall portion (hereinafter referred to as a “cavity portion”);
A plunger arranged in the cavity of the body so as to be movable in the front and rear direction;
a master jaw inserted into each inclined guide hole and having its rear end engaged with the plunger;
a jaw attached to the front end of each master jaw;
When the plunger is moved backward, each master jaw is guided by the inclined guide hole, and as the plurality of jaws approach each other, the workpiece placed between the plurality of jaws is in a chucked state.
When the plunger is moved forward, each of the master jaws is guided by an inclined guide hole, and the plurality of jaws separate from each other, thereby releasing the grip on the workpiece into a non-chucked state, the retractable chuck,
A retractable chuck characterized in that a backup part that contacts the rear end of the master jaw from the outside when in the chuck state is provided on the inner peripheral side of the peripheral wall of the body.
A seal ring for sealing the gap between the inclined guide hole and the outer circumference of the master jaw is attached to the outer circumference of the master jaw,
A slotted part for letting the seal ring escape when inserting the master jaw from the rear end side of the inclined guide hole is provided in the area between the inclined guide hole and the backup part on the inner peripheral side of the peripheral wall of the body. 2. A retractable chuck according to claim 1.
A notch is provided on the outer periphery of the front end of the master jaw,
3. The structure of claim 2, wherein the notch allows the master jaw to be moved to the side opposite to the backup part inside the inclined guide hole while the seal ring overlaps the backup part when inserting the master jaw. Retractable chuck.
An engaging protrusion is provided on the outer periphery of the plunger,
An engagement recess is provided on the outer peripheral portion of the rear end side of the master jaw on the side opposite to the backup portion,
2. The retractable chuck according to claim 1, wherein the master jaw is engaged with the plunger by fitting the engagement protrusion into the engagement recess.

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