JP2009241189A - Machining method of workpiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machining method of a workpiece, carrying out bore machining of the workpiece easy to have distortion when held with an outer diameter chuck. <P>SOLUTION: This machining method of the workpiece is devised to machine an inner diameter surface of a second hole 15 concentrically arranged with a first hole 14 provided on the workpiece by inserting a click part 5a of a spring collet 5 in the first hole 14, holding the work 10 by the inner diameter chuck 4 by extending the click part in diameter until it makes contact with an inner diameter surface of the first hole with pressure and relatively rotating the workpiece 10 and a tool 16 held by a tool holder 17. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a machining method for accurately machining an inner diameter of a workpiece that is likely to cause distortion with a cutting tool or the like.

  The inner diameter processing of the workpiece is performed by gripping and holding the workpiece from the outside with an outer diameter chuck, and rotating the workpiece and the tool held by the tool holder in this state to process the inner diameter surface of the hole provided in the workpiece with the tool. Is done in a way that In addition to cutting tools, abrasive tools are also used.

In the above-described method of gripping the workpiece with the outer diameter chuck, if the workpiece has a low strength, the workpiece is distorted, and the processing accuracy is deteriorated due to the distortion. For example, Patent Document 1 listed below is a document that mentions this problem. In this patent document 1, when a ring-shaped workpiece is gripped by a collet chuck and the inner diameter of the workpiece is processed, the inner diameter of the workpiece processed by deforming the inside of the workpiece larger than the inlet side due to the displacement of the collet accompanying tightening of the chuck. In order to prevent this, a method has been proposed in which the contact area of the collet claw portion with respect to the workpiece is reduced and the center portion in the thickness direction of the workpiece is held by a chuck.
JP 2007-969 A

  Although the above-mentioned Patent Document 1 eliminates the bias of holding by the chuck and prevents the distortion of the workpiece, the strain of the workpiece itself cannot be eliminated by this method. Further, it is not easy to equalize the distortion in each area of the work by adjusting the holding point, and there is a work to which the method cannot be applied.

  For example, the workpiece 10 shown in FIG. 2 has a boss portion 2 formed on one surface side of the disc-shaped base portion 11 and a concentric first axis having an end surface 3 perpendicular to the axis on the other surface side of the base portion 11. A hole 4 is formed, and a second hole 5 extending from the first hole 4 to the tip of the boss portion 2 is formed. Conventionally, such a workpiece 10 has been processed in the second hole 5 by gripping the outer periphery of the base 11 with an outer diameter chuck. However, since it has a shape that cannot ensure high strength, the holding point is adjusted by the chuck. However, the distortion of the portion where the second hole 5 exists cannot be made uniform. Therefore, in the method disclosed in Patent Document 1, it is not possible to expect complete homogenization of the strain, and it is inevitable that the processing accuracy is lowered due to the influence of strain bias.

  Moreover, since the method of Patent Document 1 reduces the contact area of the chuck with the workpiece, it also adversely affects the holding stability of the workpiece and the stability of processing. In addition, it is necessary to adjust the holding point by the chuck in order to reduce the bias of the strain, and the processing becomes complicated.

  An object of the present invention is to enable stable inner diameter processing with high accuracy even for a workpiece as shown in FIG.

  In order to solve the above-mentioned problem, in the present invention, the claw portion of the inner diameter chuck having a spring collet is inserted into the first hole of the workpiece and the claw portion is expanded in diameter, thereby the claw portion. Is held in pressure contact with the inner diameter surface of the first hole, and in this state, the work and the tool held by the tool holder are rotated relative to each other so as to be concentric with the first hole provided in the work. A method of machining the inner diameter surface of the second hole with the tool is adopted.

  In the inner diameter chuck used in such a method, a pressure transmission medium formed of rubber is arranged inside the spring collet, and the pressure transmission medium is pressurized in the axial direction by a pressure member drawn by a draw bar, and the pressure medium It is preferable to expand the claw portion by radially inflating the spring collet with a bulging pressure transmission medium from the inside to the outside in the radial direction.

  Further, when the first hole has an end surface perpendicular to the axis, it is preferable that the tip of the claw portion of the spring collet is abutted against the end surface to position the workpiece in the axial direction.

  In the method of the present invention, the second hole provided in the workpiece is processed with a workpiece which is distorted when the outer diameter surface is gripped with a pressure capable of obtaining a required holding force by the outer diameter chuck. The effectiveness is demonstrated when the inner diameter processing is performed.

  It is more advantageous to machine a work that does not distort even if the outer diameter surface is gripped with a required pressure, using a general outer diameter chuck. However, the method of the present invention can also be used for the inner diameter machining of such a workpiece, and does not limit the workpiece to be machined.

  In the method of the present invention, since the workpiece is held by the inner diameter chuck, a workpiece that is weak against tightening from the outside (a workpiece that generates strain when the outer diameter surface is gripped by the outer diameter chuck) is also held without generating a large strain. Therefore, a decrease in machining accuracy due to distortion due to the holding force of the workpiece is suppressed.

  If an internal diameter chuck that uses a rubber pressure transmission medium to convert the axial pressure to radial pressure to operate the spring collet is used, uniform pressure acts on each claw of the spring collet, and the claw The diameter expansion amount is constant, and the centering accuracy of the workpiece and the holding stability by the inner diameter chuck are increased, so that better machining accuracy can be expected.

  Further, when the first hole has an end surface perpendicular to the axis, the tip of the claw portion of the spring collet can be abutted against the end surface and the workpiece can be positioned in the axial direction and held by the inner diameter chuck. By adopting, the workpiece can be easily and stably positioned in the axial direction without providing any special positioning means.

  Hereinafter, an embodiment of a workpiece machining method according to the present invention will be described with reference to FIG. 1 of the accompanying drawings. The example machining method is an example of machining the workpiece 10 described in FIG. 2, and the inner diameter of the second hole 15 of the workpiece 10 is set with a tool 16 (in the drawing, a cutting tool). Process.

  1 in the figure is a main shaft of a processing machine (not shown). A face plate 3 is attached to the tip of the main shaft 1 incorporating the draw bar 2 therein, and an inner diameter chuck 4 is assembled to the face plate 3.

  The inner diameter chuck 4 is disclosed in the above-mentioned Patent Document 2, and includes a spring collet 5, a pressure transmission medium 6 disposed inside the collet, and pressurization that pressurizes the pressure transmission medium 6 in the axial direction. The member 7 is combined to hold the workpiece 10 by the spring collet 5 and release the holding by operating the draw bar 2 connected to the pressing member 7 through the joint 8.

  The spring collet 5 has a plurality of claw portions 5a. The claw portion 5a is created by dividing a cylinder into a plurality of circumferentially divided longitudinal grooves 5b arranged at a constant pitch in the circumferential direction, with the base end (left side portion of the dividing groove 5b) side as a fulcrum. Due to the elastic deformation, the diameter of the distal end side can be increased from the proximal end.

  The pressure transmission medium 6 employs a sleeve-like component made of urethane rubber. Further, the pressure member 7 is provided with an end plate 7 b at the tip of a shaft portion 7 a inserted into the center of the spring collet 5. The pressure transmission medium 6 is accommodated in the space between the claw part 5a and the shaft part 7a. Reference numeral 8 in FIG. 1 denotes a protective sleeve that prevents excessive deformation of the claw portion 5a. The protective sleeve 8 may be provided on the outer periphery of the spring collet 5 as required.

  In the inner diameter chuck 4 configured as described above, when the draw bar 2 is pulled, the pressure transmission medium 6 sandwiched between the end plate 7b of the pressure member 7 and the inner end surface of the spring collet 5 is pressurized in the axial direction. The pressure transmission medium 6 swells in the radial direction by the pressurization, and the swelled pressure transmission medium 6 presses the spring collet 5 radially outward from the inside to expand the diameter of the claw portion 5a.

  In FIG. 1, the claw portion 5a of the spring collet 5 is inserted into the first hole 14 of the workpiece 10 until the tip of the claw portion 5a hits the end face 13, and the claw portion 5a is expanded in diameter at this position. To press contact with the inner diameter surface of the first hole 14. When the pressure contact is made, the workpiece 10 is fixed and held by the inner diameter chuck 4. At the same time, the workpiece 10 is axially positioned.

  In this state, the workpiece 10 and the tool 16 held by the tool holder 17 are relatively rotated (in the example shown in the figure, the workpiece 10 is rotated together with the spindle 1), and the tool 16 is fed in a non-rotating state and cut into the workpiece 10. The inner diameter of the second hole 15 is processed.

  The pressure is uniformly applied to each claw portion 5a of the spring collet by the action of the pressure transmission medium 6, so that the diameter expansion amount of each claw portion is constant, the centering accuracy of the workpiece 10 and the holding stability by the inner diameter chuck 4 are improved. It is growing. Since the above inner diameter processing is performed in this state, the processing accuracy is improved as compared with the conventional processing method in which the workpiece is held by the outer diameter chuck and the inner diameter processing of the second hole 15 is performed.

  For example, the thickness t = 2.5 mm and the outer diameter D = 69 mm of FIG. 1 formed of an iron-based sintered alloy, the inner diameter d1 of the first hole 14 = 63 mm, and the inner diameter d2 of the second hole 15 = 32 mm. In the inner diameter machining of the workpiece 10, in the case of the conventional method in which the outer diameter is gripped by the outer diameter chuck, about 4% of the workpieces are determined to be defective because the machining accuracy of the second hole is poor. The workpiece processed by the method of the present invention had a defect rate of zero.

Sectional drawing which shows embodiment of the machining method of this invention Cross section of spring collet Sectional drawing which shows an example of the workpiece | work processed by the method of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main axis | shaft 2 Draw bar 3 Face board 4 Inner diameter chuck 5 Spring collet 5a Claw part 5b Split groove 6 Pressure transmission medium 7 Pressurizing member 7a Shaft part 7b End plate 8 Protection sleeve 10 Work part 11 Base part 12 Boss part 13 End face 14 First hole 15 Second hole 16 Tool 17 Tool holder

Claims (3)

  By inserting the claw portion (5a) of the spring collet (5) into the first hole (14) of the work (10) and expanding the diameter of the claw portion (5a), the claw portion (5a) is The workpiece (10) is held by the inner diameter chuck (4) provided with the spring collet (5) by being brought into pressure contact with the inner diameter surface of the hole (14), and in this state, the workpiece (10) and the tool holder (17 ) Is rotated relative to the inner surface of the second hole (15) concentrically arranged with the first hole (14) provided in the workpiece (10). ) Machining method for workpieces to be machined.   As the inner diameter chuck (4), a pressure transmission medium (6) made of rubber is disposed inside the spring collet (5), and the pressure transmission medium (6) is axially moved by a pressure member (7). The pressure transmission medium (6) is expanded in the radial direction by applying pressure, and the spring collet (5) is pressed radially outward from the inside with the expanded pressure transmission medium (6) to thereby form the claw portion (5a). The workpiece machining method according to claim 1, wherein a workpiece whose diameter is expanded is used.   The first hole (14) has an end surface (13) perpendicular to the axis, and the tip of the claw portion (5a) of the spring collet (5) is abutted against the end surface (13) to pivot the workpiece (10). The workpiece machining method according to claim 1, wherein the workpiece is machined in a direction.

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