JP4072888B2 - Chuck - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chuck suitable for grasping a thin cylindrical workpiece.
[0002]
[Prior art]
Since a thin cylindrical workpiece is soft and easily distorted, conventionally, a technique has been proposed in which a large number of grasping portions are arranged in the chuck circumferential direction to disperse the grasping force. For example, Japanese Patent Laid-Open No. 10-249614 (first conventional example) shows a chuck in which a number of hydraulic cylinders are arranged radially in a chuck body and a workpiece is grasped by a rod of each cylinder. In Japanese Patent Publication No.57-46964 (second conventional example), nine gripping claws are provided at one location in the chuck axis direction, and the remaining six grips until three gripping claws center the workpiece. A chuck is shown in which the gripping claws are provided so as to be displaceable. In Japanese Utility Model Laid-Open No. 55-31532 (third conventional example), three grasping claws that respectively swing are arranged on a plurality of planes perpendicular to the central axis of the chuck, and centering and grasping by these grasping claws. Thus, there is disclosed a chuck in which the center of the workpiece and the grasping center coincide with each other in each plane.
[0003]
[Problems to be solved by the invention]
However, according to the chuck of the first conventional example, since the hydraulic cylinders are arranged in a radial manner, there is a problem in that the centrifugal force acts on the piston during high-speed rotation to reduce the grasping force. According to the chuck of the second conventional example, since all the gripping claws are arranged at one place in the chuck axis direction, sufficient rigidity against the moment due to the cutting force is obtained when a long workpiece is cut in the chuck axis direction. There was a problem that could not be secured. In the chuck of the third conventional example, each of the three grasping claws in each vertical plane is grasped by moving the same distance in the radial direction. However, a gripping claw that cannot grasp the workpiece occurs due to variations in the workpiece outer diameter accuracy, and the workpiece cannot be grasped uniformly. In addition, in order to reduce the grasping load at one grasping point, the grasping portions of the three grasping claws located in each plane are swung so that there are six workpiece grasping points. There was a problem that it could not be more than that and was not suitable for further heavy cutting.
[0004]
Therefore, the problem of the present invention is to suppress a decrease in grasping force due to centrifugal force, increase rigidity, accurately grasp a workpiece with variations in outer diameter dimensions, and can be applied to high-speed rotation, heavy cutting, high-precision machining, In particular, it is to provide a chuck suitable for grasping a thin cylindrical workpiece.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the chuck according to the invention of claim 1 supports a large number of master jaws at two front and rear positions of the chuck body so as to be movable in the chuck radial direction, and supports a work on the three master jaws on the front side. A front centering jaw for centering is provided, and a plurality of remaining master jaws on the front side are provided with a front gripping jaw for grasping the workpiece later than the front centering jaw, and a rear centering centering the workpiece on the three master jaws on the rear side. A post-holding jaw is provided on the remaining master jaws on the rear side to grasp the workpiece later than the rear centering jaw, and a long wedge bar in the chuck axis direction is provided on all master jaws in the longitudinal direction via the wedge. A guide hole for guiding the wedge bar is formed in the chuck body, and the wedge bar is driven in the chuck axis direction. The drive mechanism is provided, said drive mechanism, a first spider that all the wedge bar passes, a driving member for driving the first spider to the chuck axis direction, each wedge bar leading to the front centering jaw to the chuck axis direction A second spider that is connected so as to be movable integrally, a third spider that connects each wedge bar connected to the rear centering jaw so as to be integrally movable in the chuck axis direction, and a first spring that transmits the power of the first spider to the second spider A member, a second spring member for transmitting the power of the first spider to the third spider, and a third spring member for separately transmitting the power of the first spider to each wedge bar connected to the front and rear grasping jaws. Features .
[0008]
The chuck according to the second aspect of the present invention uses the frictional force between the chuck body and the wedge bar to effectively prevent a decrease in the gripping force due to the centrifugal force. Further, the wedge bar is formed with a hole penetrating through a gap in the chuck radial direction.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 4, in the chuck of this embodiment, a holding cylinder 2 is integrally projected on the front portion of the chuck body 1, and a dust-proof cup 3 is fitted on the outer periphery of the holding cylinder 2. Yes. A back plate 4 is assembled with bolts 5 on the rear end surface of the chuck body 1, and a plurality of holes 6 (see FIG. 2) are formed in the back plate 4. The bolts 7 inserted into the holes 6 serve as a main spindle such as a lathe. Attached to.
[0010]
At the front end of the holding cylinder 2, nine front holes 9 are circumferentially provided in the chuck radial direction at equal angular intervals of 40 °, and the front master jaw 10 can slide in each front hole 9. Has been inserted. At the rear end of the holding cylinder 2, nine rear holes 11 in the circumferential direction are provided in the chuck radial direction at an equal angular interval of 40 ° at a phase different from the front hole 9 by 20 °, and each rear hole 11, a rear master jaw 12 is slidably inserted. Accordingly, a total of 18 master jaws 10 and 12 are arranged at two different positions around the chuck axis at equal angular intervals of 20 ° at two positions on the front and rear sides of the chuck body 1 (see FIG. 3).
[0011]
Of the nine front master jaws 10, three master jaws 10A positioned at equal angular intervals of 120 ° are provided with front centering jaws 14 for centering the front end of the thin cylindrical workpiece W. . The remaining six front master jaws 10 are provided with a front grasping jaw 15 for grasping the front end of the work W after the front centering jaw 14. These jaws 14 and 15 are fixed to the inner surface of the holder 16, and the holder 16 is attached to the inner end of the front master jaw 10 with a bolt 18 through a spacer 17.
[0012]
In addition, by adjusting the thickness of the spacer 17, the radial mounting positions of the jaws 14 and 15 with respect to the master jaw 10 (10 </ b> A) are set in accordance with the outer diameter size of the workpiece to be grasped.
[0013]
Of the nine rear master jaws 12, three rear master jaws 12A positioned at equal angular intervals of 120 ° are provided with rear centering jaws 21 for centering the rear end of the thin cylindrical workpiece W. The remaining six rear master jaws 12 are provided with rear grasping jaws 22 for grasping the rear end of the work W after the rear centering jaw 21. These jaws 21 and 22 are attached to the inner end of the rear master jaw 12 by the same attachment structure as the front jaws 14 and 15.
[0014]
The front and rear master jaws 10 (10A) and 12 (12A) are assembled with a wedge bar 24 which is long in the chuck axis direction, and each wedge bar 24 can be separately slid in the chuck axis direction on the holding cylinder 2 of the chuck body 1. A guide hole 25 for guiding is formed. As shown in FIGS. 6 and 7, a flat portion 26 is formed at the front end portion of the wedge bar 24, and a protruding wedge portion 27 is provided on both side surfaces of the flat portion 26 so as to project obliquely downward. The master jaws 10 and 12 are formed with a radial groove 28 into which the flat portion 26 is fitted, and a grooved wedge portion 29 that engages with the protruding wedge portion 27 is recessed in the radial groove 28.
[0015]
The wedge bar 24 is coupled to all the master jaws 10 and 12 through the wedge portions 27 and 29 so as to be slidable in the longitudinal direction. Each master jaw 10 and 12 is closed when the wedge bar 24 is retracted, and when the wedge bar 24 is advanced. Opened. The 6 wedge bars 24 connected to the centering jaws 14 and 21 and the 12 wedge bars 24 connected to the grasping jaws 15 and 22 have slightly different engagement positions in the chuck axis direction of the wedge portions 27 and 29. At the forward end of the wedge bar 24, the grasping jaws 15 and 22 are positioned on a circumference slightly larger in diameter than the centering jaws 14 and 21, and when the wedge bar 24 is retracted, the grasping jaws 15 and 22 are centered. The workpiece W is grasped later than the jaws 14 and 21.
[0016]
As shown in FIGS. 1 and 2, a drive mechanism 32 that drives each wedge bar 24 in the chuck axis direction is installed inside the chuck body 1. The drive mechanism 32 includes three spiders 33, 34, and 35 movably in the chuck axis direction, and the intermediate first spider 33 is guided by a small diameter portion of a guide member 36 fixed to the chuck body 1, and the second spider 33 on the rear side. The spider 34 is guided by the boss portion of the first spider 33, and the front third spider 35 is guided by the large diameter portion of the guide member 36.
[0017]
The boss portion of the first spider 33 is coupled to a draw screw 39 by a bolt 38, and the draw screw 39 is connected to an external actuator (not shown) (for example, a rotary cylinder installed on the main shaft side). A drive member for driving 33 in the chuck axis direction is configured. In addition, 18 holes 40 are formed in the outer peripheral portion of the first spider 33, and all the wedge bars 24 are larger in the chuck radial direction gaps than the sliding gaps between the guide holes 25 and the wedge bars 24. It is penetrated separately via a gap g.
[0018]
As shown in FIG. 5, three holes 41 are formed in the second spider 34, and the rear ends of the three wedge bars 24 connected to the front centering jaw 14 in each hole 41 form a gap g in the chuck radial direction. It is penetrated separately through. A retaining plate 44 is disposed on the back side of the second spider 34 and is fixed to the rear end surface of each wedge bar 24 with a bolt 43. A first compression spring 45 is fitted into the wedge bar 24 between the first spider 33 and the second spider 34, and the second spider 34 is pushed rearward by the spring force to come into contact with the retaining plate 44. Yes. With this configuration, the three wedge bars 24 connected to the front centering jaw 14 are coupled to the second spider 34 so as to be integrally movable in the chuck axis direction, and the power of the first spider 33 is transmitted via the first compression spring 45. 2 is transmitted to the spider 34.
[0019]
As shown in FIG. 1, 18 holes 42 are formed in the third spider 35, and all the wedge bars 24 are individually penetrated through the holes 42 through the gaps g in the chuck radial direction. The three wedge bars 24 connected to the jaw 21 are connected to the third spider 35 by an intermediate flange 46 and a screw 48 so as to be integrally movable in the chuck axis direction. A spring receiver 47 is provided at the rear ends of the three wedge bars 24, and a second compression spring 49 is inserted into the wedge bar 24 between the spring receiver 47 and the first spider 33. Thus, the power of the first spider 33 is transmitted to the third spider 35.
[0020]
On the other hand, as shown in FIG. 2, spring receivers 50 are fixed with bolts 51 to the rear ends of a total of 12 wedge bars 24 connected to the front grasping jaw 15 and the rear grasping jaw 22. An escape hole 52 for allowing the head of the bolt 51 to escape when the wedge bar 24 is retracted is provided. A third compression spring 53 is inserted into the wedge bar 24 between the spring receiver 50 and the first spider 33, and the power of the first spider 33 is transmitted to the front and rear grasping jaws 15 and 22 through the compression spring 53. Each of the 12 wedge bars 24 is transmitted separately.
[0021]
A work stopper 55 is housed inside the guide member 36 so as to be able to advance and retract in the chuck axis direction, and is driven by an external actuator (not shown) on the main shaft side via a screw rod 56 and a draw sleeve 57 to chuck the work W. It can be positioned on the axis.
[0022]
Next, the operation of the chuck configured as described above will be described. In the chuck rest state, the work stopper 55 stops at the retracted end position, the draw screw 39 and the first spider 33 stop at the advanced end position, all the compression springs 45, 49, 53 extend, and all the wedge bars 24 stops at the forward end position, all the master jaws 10 and 12 open outward in the chuck radial direction, and all the jaws 14, 15, 21, and 22 stop at the fully open position.
[0023]
When processing the thin cylindrical workpiece W, the workpiece stopper 55 is advanced, the workpiece W is inserted and positioned by the stopper 55, and then the first spider 33 is retracted by the draw screw 39. As a result, as shown in FIG. 5, the second spider 34 is retracted via the first compression spring 45, the three wedge bars 24 connected to the front centering jaw 14 are retracted, and the wedge action of the wedge portions 27 and 29 is performed. As a result, the three front master jaws 10A are closed, and the three front centering jaws 14 center the three front ends of the workpiece W. At this time, since each wedge bar 24 is connected to the second spider 34 so as to be integrally movable, the three front centering jaws 14 are closed by the same amount, and the front end of the workpiece W can be accurately centered.
[0024]
As the first spider 33 is retracted, as shown in FIG. 1, the third spider 35 is retracted via the second compression spring 49, the three wedge bars 24 connected to the rear centering jaw 21 are retracted, and the wedges are retracted. The three rear master jaws 12A are closed by the wedge action of the portions 27 and 29, and the three rear centering jaws 21 center the three rear ends of the workpiece W. Also at this time, since each wedge bar 24 is connected to the third spider 35 so as to be integrally movable, the three rear centering jaws 21 are closed by the same amount in the chuck radial direction, and the rear end of the workpiece W is closed to the front centering jaw. 14 can be accurately centered at the same timing.
[0025]
After the workpiece W is centered, the 12 wedge bars 24 connected to the front and rear grasping jaws 15 and 22 are retracted via the third compression spring 53 by further retracting the first spider 33, as shown in FIG. By the wedge action of the wedge portions 27 and 29, the six front master jaws 10 and the six rear master jaws 12 are simultaneously closed. The six front grasping jaws 15 grasp the six front end positions of the workpiece W, and the six rear grasping jaws 22 grasp the six rear end positions of the workpiece W. At this time, since the spring force of the third compression spring 53 acts on each wedge bar 24 separately, even if there is a variation in the outer diameter at the grasping position of the workpiece W, this is applied to the third compression spring 53. Thus, both the front and rear ends of the workpiece W can be accurately grasped by the grasping jaws 15 and 22, thereby enabling high-precision machining using a lathe or the like.
[0026]
In addition, the front and rear centering jaws 14 and 21 simultaneously grasp the workpiece W at the same time as the grasping jaws 15 and 22, so that the front end and the rear end of the workpiece W can be grasped powerfully at 9 locations respectively, and heavy cutting with a lathe or the like is possible. It becomes. In addition, since the 18 master jaws 10 and 12 are arranged at different angles around the chuck axis at equal angular intervals, all the jaws 14, 15, 21, and 22 are all around the front end and the rear end of the workpiece W. The entire circumference can be grasped with a uniform force, and deformation of the thin cylindrical workpiece W can be reliably prevented.
[0027]
When the chuck is rotated in this grasping state, the wedge bar 24 is moved forward through the wedge action of the wedge portions 27 and 29 by the centrifugal force acting on the master jaws 10 and 12, and the jaws 14, 15, 21, and 22 are moved. Try to open. However, since all the wedge bars 24 are inserted into the guide holes 25 of the holding cylinder 2 and penetrated through the holes 40, 41, and 42 of the spiders 33, 34, and 35 through the gap g, the wedge bar 24 is It is strongly pressed against the inner surface of the guide hole 25 by the centrifugal force, and a large frictional force is generated in the chuck body 1, and the wedge bar 24 is prevented from moving forward in the chuck axis direction by this frictional force. Accordingly, a decrease in the gripping force of the jaws 14, 15, 21, 22 can be reliably prevented, and the chuck can be rotated at high speed.
[0028]
Note that the number and arrangement interval of the master jaws 10 and 12 are not limited to the above-described embodiment, and can be appropriately changed according to the outer diameter size, thickness dimension, material, and the like of the workpiece W. In addition, the shape and configuration of each part of the chuck can be changed as appropriate without departing from the spirit of the present invention.
[0029]
【The invention's effect】
As described above in detail, according to the first aspect of the present invention, a plurality of centering jaws and grasping jaws are arranged at two positions on the front and rear sides of the chuck body, and a wedge bar connected to these jaws is used as a guide hole of the chuck body. Because it is inserted, it can suppress the decrease in gripping force due to centrifugal force, increase rigidity, accurately grasp workpieces with variations in external dimensions, and can be applied to heavy cutting and high precision machining, especially thin-walled cylinders It can be suitably used for grasping a workpiece . In particular, by having a drive mechanism that separately transmits the power to the wedge bar linked to the centering jaw and the wedge bar linked to the grasping jaw, the centering and grasping accuracy can be further improved with one drive member, It has the effect of accurately grasping thin cylindrical workpieces.
[0032]
According to the invention of claim 2 , since the wedge bar is passed through the three spiders through the gap in the chuck radial direction, the friction force between the chuck body and the wedge bar is effectively used, and the grasping force by the centrifugal force is obtained. There is an effect that can surely prevent the lowering of.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a chuck showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the chuck at a phase different from that of FIG.
FIG. 3 is a front view of the chuck of FIG. 1;
4 is an enlarged view of a central portion of FIG.
5 is a cross-sectional view taken along line AA in FIG.
6 is a cross-sectional view taken along line BB in FIG.
7 is a cross-sectional view taken along the line CC in FIG. 1. FIG.
[Explanation of symbols]
1 .... Chuck body, 10 .... Front master jaw, 12 .... Rear master jaw, 14 .... Front centering jaw, 15 .... Front gripping jaw, 21 ... Rear centering jaw, 22 .... Back gripping jaw, 24 ... Wedge bar 25 ... Guide hole 27 ... Wedge part 29 ... Wedge part 32 ... Drive mechanism 33 ... First spider 34 ... Second spider 35 ... Third spider , 39 .. Draw screw, 40, 41, 42 .. hole, 45 .. First compression spring, 49 .. Second compression spring, 53 .. Third compression spring, 55 .. Work stopper, g. , W. Work.

Claims (2)

A large number of master jaws are supported at two positions on the front and back of the chuck body so as to be movable in the chuck radial direction, and front centering jaws for centering the workpiece are provided on the three front master jaws. A pre-holding jaw is provided to grasp the workpiece later than the front centering jaw, a rear centering jaw is provided for centering the workpiece on the three rear master jaws, and a rear centering jaw is provided to the remaining master jaws on the rear side. A gripping jaw is provided to grasp the workpiece later, and a wedge hole that is long in the chuck axis direction is coupled to all the master jaws so as to be movable in the longitudinal direction via the wedge portion, and guide holes for guiding the wedge bar to the chuck body to form a, a driving mechanism for driving the wedge bars to the chuck axis direction is provided, said drive mechanism, be through a total of wedge bar A first spider, a driving member that drives the first spider in the chuck axis direction, a second spider that connects each wedge bar connected to the front centering jaw so as to be integrally movable in the chuck axis direction, and a rear centering jaw A third spider that connects each wedge bar so as to be integrally movable in the chuck axis direction, a first spring member that transmits the power of the first spider to the second spider, and a second spring that transmits the power of the first spider to the third spider A chuck comprising: a member; and a third spring member for separately transmitting the power of the first spider to each wedge bar connected to the front and rear grasping jaws . The chuck according to claim 1, wherein the first, second and third spiders are formed with holes through which the wedge bar passes through a gap in the chuck radial direction .

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