JP2007030072A - Draw-down chuck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a draw-down chuck, which prevents a jaw from moving in the circumferential direction by heavy cutting of a work. <P>SOLUTION: A guide surface 18 vertical to the chuck axis CL is provided on the tip of a draw bar 8, and the guide surface 18 is provided with a groove part 18a with which a projecting part 17b provided on the lower surface of the jaw is engaged. The projecting part 17b of the jaw 17 is engaged with the groove part 18a, and the jaw 17, the fitting surface 17a of which is abutted on an abut surface 16a, is fixed to the draw bar 8 by a fitting bolt 21, whereby the circumferential force F generated in the jaw 17 by heavy cutting of the work W is canceled by the frictional force generated between the lower surface 17d of the jaw 17 and the guide surface 18 of the draw bar 8 by the fitting bolt 21 and by the engagement state of the projecting part 17b of the jaw with the groove part 18a of the guide surface 18. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  According to the present invention, a protrusion protruding forward from the tip of the draw bar is provided with an arc-shaped contact surface having the same dimensions as the arc-shaped mounting surface formed on the jaw, and the lower surface of the jaw is provided at the tip of the draw bar. The present invention relates to a draw-down chuck in which a guide surface is provided that abuts against the guide surface and is fixed to a draw bar with a mounting bolt.

Conventionally, drawdown chucks have a plurality of inclined axis guide holes that are inclined with respect to the chuck axis in the chuck body, and each guide hole is slidably fitted with a draw bar and moved back and forth in the chuck axis direction. Each draw bar is advanced and retracted in the direction of the tilt axis by the draw sleeve. The protrusion protruding forward from the tip of the draw bar is provided with an arc-shaped contact surface having the same dimensions as the arc-shaped mounting surface formed on the jaw, and the lower surface of the jaw is applied to the tip of the draw bar. It is known that a guide surface that is in contact is provided, and a jaw that is in contact with the contact surface and the guide surface is fixed to a draw bar with a mounting bolt. Patent Document 1 describes that a jaw is pressed in the direction of the guide surface with a mounting bolt, and Patent Document 2 describes that a jaw is pressed in the direction of the contact surface with a mounting bolt.
JP 2000-343307 A JP 2002-103109 A

  Conventionally, when machining is performed on a workpiece clamped by a plurality of jaws, a circumferential force is generated in each jaw, and the force is generated between the attachment surface of the jaw and the contact surface of the draw bar, and the lower surface of the jaw. Is canceled by the frictional force generated between the guide surface and the guide surface. In Patent Document 1, a friction force is generated between the lower surface of the jaw and the guide surface by pressing the jaw in the direction of the guide surface with a mounting bolt. In Patent Document 2, a frictional force is generated between the attachment surface of the jaw and the contact surface by pressing the jaw in the direction of the contact surface with a mounting bolt. However, if heavy cutting is performed on the workpiece, the circumferential force generated in each jaw becomes large, and the force cannot be canceled out by the frictional force. As a result, the workpiece clamping accuracy may decrease. Further, if the frictional force is to be increased by using a large-diameter mounting bolt, it is necessary to enlarge the jaw. Furthermore, there has been a problem that the jaw that moves must be supported by the shearing stress of the mounting bolt, and the mounting bolt cannot be made of a small diameter.

  Therefore, an object of the present invention is to solve the above-described problems, and an object of the present invention is to provide a drawdown chuck in which a jaw does not move in the circumferential direction by heavy cutting of a workpiece.

  The drawdown chuck of the present invention has a plurality of inclined axis guide holes inclined with respect to the chuck axis in the chuck body, and a draw bar having a jaw is slidably inserted into each guide hole, and the chuck axis is moved back and forth in the chuck axis direction. A draw-down chuck in which each draw bar is moved forward and backward in the direction of the tilt axis by a moving draw sleeve, and the protrusion protruding forward from the tip of the draw bar has the same dimensions as the arcuate mounting surface formed on the jaw. A certain arc-shaped contact surface is provided, and a guide surface is provided at the tip of the draw bar with which the lower surface of the jaw comes into contact. The jaw that is in contact with the contact surface and the guide surface is attached to the draw bar by a mounting bolt. In the drawdown chuck fixed to the guide, the guide surface is provided perpendicular to the chuck axis, and the guide surface is provided on the lower surface of the jaw. A groove with which the protrusion is engaged is provided, the protrusion on the lower surface of the jaw is engaged with the groove, and the jaw with the attachment surface abutting on the abutment surface of the protrusion is secured to the drawbar with an attachment bolt. It is characterized by comprising. Specifically, a plurality of protrusions are provided on the lower surface of the jaw from the inside to the outside, and grooves for engaging each protrusion are provided on both the left and right sides of the guide surface.

  In the present invention, a guide surface perpendicular to the chuck axis is provided at the tip of the draw bar, a groove for engaging the protrusion provided on the lower surface of the jaw is provided on the guide surface, and the protrusion on the lower surface of the jaw is used as the groove. By engaging the jaw with the mounting surface in contact with the abutment surface to the draw bar with the mounting bolt, the circumferential force generated in each jaw due to heavy cutting of the workpiece is applied by the mounting bolt. The frictional force generated between the lower surface of the jaw and the guide surface of the draw bar is canceled by the engagement state between the protrusion of the jaw and the groove portion of the guide surface. In addition, a plurality of protrusions are provided on the lower surface of the jaw from the inside to the outside, and grooves for engaging each protrusion are provided on both the left and right sides of the guide surface. Therefore, it is not necessary to use a large-diameter mounting bolt in order to increase the frictional force and shear stress. Furthermore, by using a small-diameter mounting bolt, a jaw corresponding to a small-diameter workpiece can be fixed to the draw bar, and more types of workpieces can be accommodated.

  The chuck body 2 of the drawdown chuck 1 shown in FIGS. 1 and 2 is such that the rear end surface 4 a of the front body 4 is closed by the rear cover 5 by the mounting bolt 3. A draw sleeve 6 is disposed on the chuck axis CL of the chuck body 2. The front body 4 is provided with a plurality (three) of guide holes 7 having an inclined axis DL inclined with respect to the chuck axis CL. A cylindrical draw bar 8 is slidably inserted into each guide hole 7. A cut portion 9 is formed at a position corresponding to each draw bar 8 of the large diameter portion 6 a of the draw sleeve 6, and a small diameter shaft portion 10 provided at the rear end of the draw bar 8 is fitted into each cut portion 9. Each draw bar 8 is connected to the draw sleeve 6 by latching the latching piece 11 formed at the rear end 10 to the large diameter portion 6 a of the draw sleeve 6. An attachment hole 12 is provided in the chuck body 2 so as to open to the guide hole 7. An anti-rotation member 14 that is prevented from coming off by a stopper member 13 is rotatably inserted into the mounting hole 12. The draw bar 8 is prevented from rotating by the engagement between the leading end of the rotation preventing member 14 and the rotation preventing groove 15 formed on the outer peripheral surface of the draw bar 8.

  A protrusion 16 is formed at the tip of the draw bar 8 so as to protrude forward. The protrusion 16 is provided with an arcuate contact surface 16a having the same dimensions as the arcuate mounting surface 17a formed inside the jaw 17. Further, a guide surface 18 that is perpendicular to the chuck axis CL is provided at the tip of the draw bar 8. The guide surface 18 is provided with a groove portion 18a with which a plurality of protrusions 17b provided on the jaw 17 are engaged. Each groove 18a is provided on both the left and right sides of the guide surface 18 as shown in FIG. A female thread portion 19 is provided on each of the contact surface 16 a and the guide surface 18. Next, the jaw 17 will be described. An arcuate workpiece contact surface 17c is provided outside the jaw 17 so as to correspond to the inner diameter of the workpiece W to be clamped. A plurality of (two) protrusions 17b are provided on the lower surface 17d of the jaw 17 from the inner side 17a to the outer side 17c. A mounting bolt mounting hole 20 is provided from the upper surface 17e toward the lower surface 17d. Accordingly, the jaw 17 is fixed to the draw bar 8 by the mounting bolt 21 in a state where the protrusion 17b is engaged with the groove 18a of the guide surface 18 and the mounting surface 17a is in contact with the contact surface 16a of the protrusion 16. It is like that. Further, since the jaw 17 is pressed in the direction of the guide surface 18 by the mounting bolt 21, a frictional force is generated between the lower surface 17 d of the jaw 17 and the guide surface 18. As shown in FIG. 5, when the mounting bolt mounting hole 20 is provided from the inner side 17 a to the outer side 17 c of the jaw 17, the jaw 17 is pressed in the direction of the contact surface 16 a by the mounting bolt 21. A frictional force is generated between the mounting surface 17a and the contact surface 16a of the draw bar 8.

  The drawdown chuck 1 having the above configuration is fixed to the front end of the main shaft portion 30 such as a lathe by a mounting bolt 22 provided in the chuck body 2, and the chuck body 2 rotates with the rotation of the main shaft portion 30. The draw sleeve 6 is connected to a piston (not shown) of a rotating cylinder (not shown) installed at the rear end of the main shaft portion 30 via a connecting rod 31, and the draw sleeve 6 is moved in the chuck axis CL direction by the operation of the piston. The draw bar 8 advances and retracts in the direction of the tilt axis DL as it advances and retreats. From this, the clamp of the work W retracts the piston, and the work 17 is attached to the stopper 23 fixed to the front body 4 by the jaw 17 that moves backward along the chuck axis CL via the draw bar 8 and moves outward in the chuck radial direction. The state in which W is attracted, the unclamp of the workpiece W advances the piston, and the jaw 17 moving inward in the chuck radial direction while moving forward along the chuck axis CL via the draw bar 8 is separated from the workpiece W. It is.

  When the workpiece W clamped by the drawdown chuck 1 is cut, a circumferential force F is generated in each jaw 17 in the opposite direction to the rotation direction of the chuck body 2 as shown in FIG. It will be. Conventionally, the force F is pressed against the guide surface 18 or the abutting surface 16a by the mounting bolt 21 to press the jaw 17 between the lower surface 17d of the jaw 17 and the guide surface 18 and against the mounting surface 17a of the jaw 17. The frictional force generated between the contact surface 16a cancels out. However, when heavy cutting is performed on the workpiece W, the force F generated in the jaw 17 may be so large that it cannot be canceled out by the frictional force. Further, the jaw 17 that moves in the circumferential direction may not be supported by the shearing stress of the mounting bolt 21.

  Therefore, in the draw down chuck 1 described above, a guide surface 18 that is perpendicular to the chuck axis CL is provided at the tip of the draw bar 8, and a groove portion that engages the projection 17 b provided on the lower surface 17 d of the jaw 17 with the guide surface 18. 18a is provided, and the protrusion 17b of the jaw 17 is engaged with the groove portion 18a and the jaw 17 in a state where the attachment surface 17a is in contact with the contact surface 16a is fixed to the draw bar 8 by the attachment bolt 21. The large circumferential force F generated in each jaw 17 due to heavy cutting of the friction between the lower surface 17d of the jaw 17 by the mounting bolt 21 and the guide surface 18 of the draw bar 8, and the protrusion of the jaw 17 It can be canceled by the engagement state of 17b and the groove portion 18a of the guide surface 18. Further, a plurality of protrusions 17b are provided on the lower surface 17d of the jaw 17 from the inner side 17a to the outer side 17c, and grooves 18a for engaging the respective protrusions 17b are provided on both the left and right sides of the guide surface 18, thereby Since the jaws 17 do not move in the circumferential direction during the machining, it is not necessary to use the large-diameter mounting bolt 21 in order to increase the frictional force and shear stress. Further, by using the small-diameter mounting bolts 21, the jaws 17 corresponding to the small-diameter workpiece W1 as shown in FIG. 5 can be fixed to the draw bar 8, and more types of workpieces W can be handled.

It is a front view of the drawdown chuck | zipper of this invention, and is a figure which shows the state which clamped the workpiece | work. It is the II-II sectional view taken on the line of FIG. FIG. 3 is a view as viewed from III in FIG. 2. FIG. 4 is a IV view of FIG. 2. It is a figure which shows other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Draw down chuck 2 Chuck body 6 Draw sleeve 7 Guide hole 8 Draw bar 16 Protrusion part 16a Contact surface 17 Jaw 17a Mounting surface 17b Projection part 17d Bottom surface 18 Guide surface 18a Groove part 21 Mounting bolt 17c Work contact surface CL Chuck axis DL Inclination Axis

Claims (2)

The chuck body is provided with a plurality of guide holes with inclined axes that are inclined with respect to the chuck axis, and a draw bar with a jaw is slidably inserted into each guide hole, and each draw bar is moved by a draw sleeve that moves back and forth in the chuck axis direction. A draw-down chuck that is advanced and retracted in the direction of the tilting axis, wherein the protrusion protruding forward from the tip of the draw bar has an arc-shaped contact surface having the same dimensions as the arc-shaped mounting surface formed on the jaw. A draw-down chuck is provided in which a guide surface with which the lower surface of the jaw contacts is provided at the tip of the draw bar, and the jaw in contact with the contact surface and the guide surface is fixed to the draw bar with a mounting bolt. In the above, the guide surface is provided perpendicular to the chuck axis, and the guide surface is provided with a groove for engaging a protrusion provided on the lower surface of the jaw, Drawdown chuck, characterized by comprising adhered to the drawbar the lock being in contact with the mounting surface to the contact surface of the protruding portion by the mounting bolts with the lower surface of the projection of ® U to engage the groove. 2. The drawdown chuck according to claim 1, wherein a plurality of protrusions are provided on the lower surface of the jaw from the inside to the outside, and grooves for engaging the protrusions are provided on both left and right sides of the guide surface.

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