JP2009107070A - Method and device for lapping - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for lapping, which increases the accuracy of the shape of a workpiece as well as the surface roughness, flatness, and smoothness of the surface of the workpiece. <P>SOLUTION: This method for lapping uses a lapping device. The lapping device includes: a lapping tool having a reciprocatingly driving part for a lapping tool, a mounting part for mounting the lapping tool on the reciprocatingly driving part, synthetic resin spherical lap balls, and an elastic support part for elastically supporting the lap balls on the mounting part; a table for mounting the workpiece thereon; and a feed mechanism for relatively moving the table in three axis directions orthogonal to each other. The method includes steps of: (102) obtaining a lapped amount from the difference between the workpiece surface shape data measured and the target shape; (103) obtaining a lap force from the lapped amount; (104) obtaining the feed position of the lapping tool for obtaining the pressing force thereof; and (105) lapping by moving the lapping tool to set the position of the lapping tool relative to each point on the surface to be machined, at the feed position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a lapping method and apparatus for performing surface processing with abrasive grains in a lapping agent by relatively moving a lap and a workpiece, and more specifically, after measuring the shape of a workpiece with high accuracy. The present invention relates to a lapping method and apparatus capable of realizing high-precision shape accuracy and surface accuracy by performing lapping using the measurement result.

  In lapping, a lapping agent is interposed between a tool called a lap and a workpiece, and the surface of the workpiece is machined by relative movement between the lap and the workpiece. The purpose is to improve the flatness and smoothness. As the lapping agent, a suspension in which free abrasive grains are dispersed in a liquid is usually used. An apparatus for performing this lapping process is generally an apparatus dedicated to lapping and cannot be shared with other machine tools and processing apparatuses.

As conventional processing apparatuses using loose abrasive grains, the following Patent Document 1 and Patent Document 2 are well known. Patent Document 1 describes a processing head for rotating an elastic spherical tool to process a workpiece in a polishing liquid. Patent Document 2 describes a polishing apparatus in which an elastic spherical tool is rotated by a rotating spindle and a free curved surface is polished through polishing abrasive grains dispersed in a slurry.
Japanese Patent Laid-Open No. 5-92362 JP 2002-361546 A

  As described above, lapping equipment is necessary to perform lapping, and in order to install lapping equipment in addition to machine tools, it is inevitable to secure installation space and increase equipment costs. Increased the processing and manufacturing costs. The processing apparatuses described in Patent Document 1 and Patent Document 2 are also dedicated machines and have similar problems. Furthermore, the tools of Patent Document 1 and Patent Document 2 need to be rotationally driven, and there is a problem that the structure of the tool and the drive mechanism become complicated.

  In general, lapping is not so good in terms of processing efficiency, and further improvement in processing efficiency has been demanded. Furthermore, with regard to the supply of the wrapping agent to the processing position, skilled techniques and careful work by the operator are required in order to perform a constant and uniform supply. The lapping process is aimed at improving the surface roughness of the workpiece surface and improving the flatness / smoothness as described above. The shape accuracy of the workpiece basically depends on the pre-processing, and the lapping processing cannot improve the shape accuracy of the workpiece.

  Therefore, the present invention improves the problems and drawbacks in the lapping process as described above, enables automatic machining with high accuracy and high machining efficiency with a simple configuration tool using a conventional machine tool, An object of the present invention is to provide a lapping method and apparatus capable of improving not only the surface roughness, flatness and smoothness of the workpiece surface but also the shape accuracy of the workpiece.

  In order to achieve the above object, a lapping method of the present invention comprises a reciprocating drive unit for reciprocating vibration of a lapping tool, an attaching unit for attaching to the reciprocating drive unit, a spherical wrapping ball made of synthetic resin, A wrapping tool having an elastic support portion that elastically supports the lap sphere with respect to the mounting portion, a table for mounting a workpiece, and the wrapping tool and the table relative to each other in three orthogonal directions A lapping method using a lapping device having a feed mechanism for moving the workpiece, wherein a processing amount of lapping is calculated based on a difference between measurement data obtained by measuring a machining surface shape of the workpiece and a target shape of the workpiece And a procedure for obtaining a pressing force of the lapping tool against a workpiece to achieve the machining amount under a predetermined machining condition A procedure for obtaining a feed position of the lapping tool for obtaining a pressing force of the lapping tool, and the lapping tool by the feed mechanism so that the position of the lapping tool with respect to each point on the surface of the workpiece is the feed position. And a procedure for performing lapping by moving the.

  In the lapping method described above, it is preferable that the lapping tool is provided with a protrusion amount adjusting portion that adjusts a protrusion amount of the wrap ball with respect to the attachment portion.

  In the lapping method described above, the target shape of the workpiece can be a flat surface, and high-precision flat surface processing can be performed.

  In the lapping method described above, the target shape of the workpiece can be an arbitrary three-dimensional curved surface, and high-precision three-dimensional curved surface processing can be performed.

  The lapping apparatus according to the present invention includes a reciprocating drive unit that reciprocally vibrates a wrapping tool, a mounting unit that is attached to the reciprocating drive unit, a spherical wrap ball made of synthetic resin, and the mounting unit. A wrapping tool having an elastic support portion that elastically supports the lap ball, a table for attaching a workpiece, and a feed mechanism that relatively moves the wrapping tool and the table in three axial directions perpendicular to each other. And a controller that controls the feed mechanism to move the lapping tool to a target position. The control unit is configured to obtain a processing amount of lapping processing from a difference between measurement data obtained by measuring a processing surface shape of the workpiece and a target shape of the workpiece, and the processing amount in a predetermined processing condition. For obtaining the pressing force of the wrapping tool against the workpiece for achieving the above, a procedure for obtaining a feed position of the wrapping tool for obtaining the pressing force of the wrapping tool, and the lapping for each point on the surface of the workpiece The lapping process is performed by moving the lapping tool by the feed mechanism so that the position of the tool is the feed position.

  In the above wrapping apparatus, it is preferable that the wrapping tool includes a protrusion amount adjusting unit that adjusts a protrusion amount of the wrap ball with respect to the attachment portion.

  In the above wrapping apparatus, the wrap ball is preferably made of a polyamide-based resin.

  Since this invention is comprised as mentioned above, there exist the following effects.

  Automatic machining with high accuracy and high machining efficiency is possible with a simple tool using a conventional machine tool. Moreover, there is no need to install a dedicated wrapping device, and problems such as securing an installation space and a significant increase in equipment cost can be avoided. As a result, the processing / manufacturing cost of the product can be reduced. Furthermore, not only the surface roughness, flatness, and smoothness of the workpiece surface, but also the shape accuracy of the workpiece can be greatly improved.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a lapping tool 1 used in the lapping method and apparatus of the present invention. The lapping tool 1 can be attached to a conventional machine tool for lapping. The attachment part 11 is for attaching the lapping tool 1 to the output shaft 31 of the reciprocating drive part 3 (refer FIG. 2) mentioned later. A connection hole 17 is formed in the upper portion of the attachment portion 11. The output shaft 31 of the reciprocating drive unit 3 is inserted into the connection hole 17, and the attachment unit 11 and the output shaft 31 are fixed by the fixing bolt 16.

  An adjustment screw 13 is connected below the attachment portion 11. The adjustment screw 13 is screwed into a female screw on the inner peripheral side of the adjustment dial 12 and is prevented from rotating with respect to the attachment portion 11 by a mechanism such as a key and a key groove. Furthermore, the upper part of the adjustment screw 13 is accommodated in the cavity 18 inside the attachment part 11, and the position of the adjustment screw 13 can be adjusted vertically with respect to the attachment part 11. The adjustment dial 12 is supported so as to be rotatable with respect to the mounting portion 11 and can be locked in rotation. Therefore, if the adjustment dial 12 is unlocked and rotated, the adjustment screw 13 can be moved up and down, and if the adjustment dial 12 is locked, the position of the adjustment screw 13 can be fixed.

  A coil spring-like elastic support portion 14 is fixed to the lower end portion of the adjustment screw 13. A spherical wrap ball 15 is fixed to the lower end portion of the elastic support portion 14. The wrap ball 15 is a solid body made of polyamide resin (so-called nylon or the like). The wrap ball 15 is preferably made of a material that has appropriate flexibility and appropriately holds the free abrasive grains in the wrapping agent. Synthetic resins such as polyamide resins and polypropylene resins are suitable. The elastic support portion 14 can be expanded and contracted vertically according to the spring constant of the coil spring. The wrap ball 15 is elastically supported by the elastic support portion 14.

  The protrusion amount of the wrap ball 15 with respect to the attachment portion 11 can be adjusted by rotating the adjustment dial 12. The adjustment dial 12 and the adjustment screw 13 constitute a protrusion amount adjustment unit. By adjusting the position (protrusion amount) of the lap ball 15 with respect to the mounting portion 11, the pressing force of the lap ball 15 against the workpiece can be adjusted, and the optimum according to the type of workpiece and the target surface accuracy. The pressing force can be set easily.

  FIG. 2 is a diagram showing the configuration of the wrapping apparatus 2 of the present invention. A conventional machine tool can be used as the wrapping device 2. The reciprocating drive unit 3 and the wrapping tool 1 are attached to the main shaft of a vertical machine tool (for example, a machining center or a milling machine) as shown in the figure. It can be set as the wrapping apparatus 2 of invention. Therefore, it is not necessary to install a dedicated wrapping apparatus, and problems such as securing an installation space and a significant increase in equipment cost can be avoided. As a result, the processing / manufacturing cost of the product can be reduced.

  A column 22 is erected from the rear of the bed 21 of the wrapping device 2, and a spindle head 23 is provided on the column 22 so as to be movable in the Z-axis direction (here, the vertical direction). Further, although a Z-axis feed mechanism for moving the spindle head 23 in the Z-axis direction is provided in the column 22, illustration is omitted here. The Z-axis feed mechanism may be composed of a ball screw mechanism including a ball nut and a Z-axis feed screw and a Z-axis feed motor.

  A main shaft 24 is rotatably supported on the main shaft head 23. The main shaft 24 can be fixed so as not to rotate. A tool mounting portion for attaching a tool in a replaceable manner is provided at the lower end portion of the main shaft 24. The reciprocating drive unit 3 is a drive unit for reciprocating vibration of the lapping tool 1. Here, the output shaft 31 of the reciprocating drive unit 3 performs reciprocal vibration in the Z-axis direction, and the frequency of the reciprocating vibration is about 10 to 20 Hz and the amplitude is about 5 mm.

  The lapping tool 1 is fixed to the output shaft 31 of the reciprocating drive unit 3, and a taper shank provided at the upper part of the reciprocating drive unit 3 is mounted and fixed to the tool mounting portion at the lower end of the main shaft 24. The reciprocating drive unit 3 may be configured to generate a reciprocating motion on the output shaft 31 by an electric motor or the like installed therein, or an internal mechanism for converting the rotational motion of the main shaft 24 into the reciprocating motion of the output shaft 31. You may make it provide in. In the latter case, a structure for stopping the rotation of the main body of the reciprocating drive unit 3 with respect to the spindle head 23 is required.

  A table 25 for mounting and fixing the workpiece 4 is installed on the upper surface of the bed 21. The table 25 is provided so as to be movable in the X and Y axis directions on a horizontal plane orthogonal to the Z axis direction. Further, although an X-axis feed mechanism and a Y-axis feed mechanism for moving the table 25 in the X and Y axis directions are provided, illustration is omitted here. The X-axis feed mechanism and the Y-axis feed mechanism may also be composed of a ball screw mechanism and a feed motor. The X, Y, and Z axes are orthogonal to each other to form an orthogonal coordinate system. The wrapping tool 1 and the workpiece 4 can be moved relative to each other in three orthogonal directions by means of the X, Y, and Z axis feed mechanisms, and can process a three-dimensional arbitrary curved surface.

  A processing tank 26 is installed so as to surround the periphery of the workpiece 4 fixed on the table 25. The connecting portion between the processing tank 26 and the table 25 is kept watertight by a seal or the like so that the lapping agent does not leak out. The lapping agent is stored inside the processing tank 26 so that the workpiece 4 is completely immersed in the lapping agent. The upper surface of the processing tank 26 is open and does not hinder processing. When a conventional machine tool is used, it is preferable that the processing tank 26 has a structure that can be easily removed.

  Actual processing is performed as follows. The workpiece 4 and the processing tank 26 are mounted on the table 25, and a lapping agent is injected into the processing tank 26 so that the workpiece 4 is immersed in the lapping agent. The adjustment dial 12 is rotated to adjust the vertical position of the lap ball 15 and the pressing force of the lap ball 15 against the workpiece 4 is set. The vibration drive of the reciprocating drive unit 3 is started and the spindle head 23 is lowered to the machining position. Then, relative movement in the X, Y, and Z axis directions is performed along the shape of the processing surface to perform lapping processing. Note that the lapping tool 1 does not rotate and only reciprocating vibration is applied.

  Due to the reciprocating vibration of the lapping tool 1, the lapping ball 15 is pressed against the surface of the workpiece 4 or separated from the surface of the workpiece 4. By this movement of the wrap ball 15, the inflow and outflow of the wrap agent between the wrap ball 15 and the workpiece 4 are continuously repeated. As a result, the supply and removal of the lapping agent is repeated between the lapping ball 15 and the workpiece 4 to automatically update the lapping agent to a fresh lapping agent, and the machining efficiency is improved by the movement of the abrasive grains in the lapping agent. . In addition, the use of the processing tank 26 eliminates the need for operator's skill in supplying the lapping agent, and enables automatic operation of the lapping apparatus 2.

  The relative movement of the lapping tool 1 and the workpiece 4 in the X, Y, and Z-axis directions can be performed using the NC machining program of the previous machining as it is or with slight modifications such as changing the offset amount. it can. Even when the same NC machining program is used, the pressing force of the lap ball 15 against the workpiece 4 can be arbitrarily set by rotating the adjustment dial 12 to adjust the vertical position of the lap ball 15.

  In FIG. 2, the processing tank 26 is mounted on the table 25. However, the form of the processing tank is not limited to this, and any type can be used as long as it can hold the lapping agent on the processing surface. It may be a thing. For example, a container opened only on the upper surface may be used as a processing tank, and the periphery of the processed portion of the workpiece may be surrounded by a wall formed of clay or a sealing material. Clay and sealing materials can also be installed directly on the workpiece. Further, as described above, it is preferable to use a processing tank, but processing without using a processing tank is also possible.

  Next, the example of a process by the wrapping apparatus 2 is given. A nylon sphere having a diameter of 6 mm was used as the lapping sphere, and the lapping agent was a mixture of water, chickenpox, and diamond abrasive grains. As a workpiece, lapping processing of a cemented carbide V10 (JIS notation) in a planar shape was performed. The pressing force of the lapping ball was 20 N or less. As a result, a smooth mirror surface having a surface roughness (maximum height Rz) of 0.07 μm was obtained.

  The pressing force of the wrapping ball is about 200 N when the surface roughness is about 1 μm when the diameter of the wrapping ball is 6 mm, and is about 20 N when the surface roughness is 0.1 μm or less. When the diameter of the wrap ball is smaller than this, it is necessary to reduce the pressing force.

  As described above, the lapping apparatus 2 performs normal lapping for improving the surface roughness, flatness, and smoothness of the workpiece surface. Next, a machining method for improving the shape accuracy of a workpiece by lapping using the lapping apparatus 2 will be described. FIG. 3 is a flowchart showing the procedure of the lapping method. Hereinafter, each procedure of the lapping method of the present invention will be described with reference to FIG.

  In the lapping method of the present invention, first, in step 101, the three-dimensional shape of the workpiece to be lapped is measured with high accuracy. The measurement device uses a high-precision three-dimensional measurement device, a confocal laser microscope, an atomic force microscope, or the like, and performs measurement with high accuracy of 1 μm or less. Next, in step 102, a lapping amount at each point of the workpiece is obtained from the difference between the target shape of the workpiece and the three-dimensional shape data measured in step 101.

  Next, in step 103, a lapping force (a lapping ball pressing force) for obtaining the lapping amount is obtained. Although the lapping amount and the lapping force are considered to be in a proportional relationship, the proportionality constant is obtained in advance through experiments or the like. At this time, the adjustment dial 12 and the adjustment screw 13 are set at the standard positions. The amount of lapping processing also depends on other processing conditions, but the other processing conditions may be fixed to the conditions for actual processing. The processing conditions other than the lapping force include the material of the workpiece, the type and composition of the lapping agent, the diameter and material of the lapping ball, the relative moving speed of the lapping tool and the workpiece.

  Next, in step 104, the position of the lapping tool for obtaining the lapping force is obtained from the three-dimensional shape data of the workpiece and the lapping force at each point on the machining surface of the workpiece. Since the lapping force is generated by the elastic constant of the elastic support portion 14, the position of the lapping tool for obtaining a desired lapping force is uniquely determined. If the position of the lapping tool at each machining point is connected, the locus of the lapping tool with respect to the workpiece is obtained. The locus of the lapping tool can be saved as an NC (numerical control) machining program.

  Next, in step 105, an NC machining program for instructing the locus of the lapping tool is executed by the lapping apparatus 2 to perform lapping. When the lapping process is executed, the lap force can be adjusted to be stronger or weaker than the standard by the adjustment dial 12. By performing the lapping process as described above, the difference between the 3D shape data of the workpiece obtained by the 3D shape measurement and the target shape is removed with high accuracy by the lapping process, and the surface roughness of the workpiece surface As well as improving the shape accuracy of the workpiece.

  For example, when the target shape of the workpiece is a flat surface, the portion having a large deviation from the flat surface obtained by the three-dimensional shape measurement is processed more to make the finished shape of the lapping processing a highly accurate planar shape. it can. The target shape of the workpiece may be an arbitrary three-dimensional curved surface. For example, any three-dimensional curved surface shape such as a rotating paraboloid, a spherical surface, or a cylindrical surface can be processed. By measuring the deviation of the workpiece from the target shape by the three-dimensional shape measurement and machining more portions with a large deviation, a highly accurate three-dimensional curved surface shape can be formed.

  Each procedure shown in FIG. 3 can be performed using an NC (Numerical Control) device (not shown) provided in the wrapping device 2. If the NC device has an NC machining program automatic creation function, it is possible to smoothly execute from the NC machining program creation to lapping.

  As described above, according to the lapping method and apparatus of the present invention, it is possible to perform automatic machining with high accuracy and high machining efficiency by using a tool with a simple configuration using a conventional machine tool. Moreover, there is no need to install a dedicated wrapping device, and problems such as securing an installation space and a significant increase in equipment cost can be avoided. As a result, the processing / manufacturing cost of the product can be reduced. Furthermore, the lapping method of the present invention can greatly improve not only the surface roughness, flatness, and smoothness of the workpiece surface but also the shape accuracy of the workpiece.

  According to the present invention, automatic machining with high accuracy and high machining efficiency can be performed with a tool having a simple configuration using a conventional machine tool. Moreover, it is not necessary to install a dedicated wrapping device, and the processing / manufacturing cost of the product can be reduced. Furthermore, not only the surface roughness, flatness, and smoothness of the workpiece surface, but also the shape accuracy of the workpiece can be greatly improved.

It is a figure which shows the structure of the lapping tool 1 used for this invention. It is a figure which shows the structure of the wrapping apparatus 2 of this invention. It is a flowchart which shows the procedure of the lapping processing method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lapping tool 2 Lapping device 3 Reciprocating drive part 4 Workpiece 11 Mounting part 12 Adjustment dial 13 Adjustment screw 14 Elastic support part 15 Lapping ball 16 Fixing bolt 17 Connection hole 18 Hollow part 21 Bed 22 Column 23 Spindle head 24 Spindle 25 Table 26 Processing tank 31 Output shaft

Claims (7)

A reciprocating drive unit (3) for reciprocatingly vibrating the lapping tool (1);
An attachment portion (11) for attachment to the reciprocating drive portion (3), a spherical wrap ball (15) made of synthetic resin, and the wrap ball (15) elastically against the attachment portion (11) A lapping tool (1) comprising an elastic support (14) for supporting
A table (25) for mounting the workpiece (4);
A lapping method using a lapping apparatus having a feed mechanism for relatively moving the lapping tool (1) and the table (25) in three axis directions orthogonal to each other,
A procedure (102) for determining a lapping machining amount from a difference between measurement data obtained by measuring a machining surface shape of the workpiece (4) and a target shape of the workpiece (4);
A procedure (103) for obtaining a pressing force of the lapping tool (1) on the workpiece to achieve the machining amount under a predetermined machining condition;
A procedure (104) for obtaining a feed position of the lapping tool (1) for obtaining a pressing force of the lapping tool (1);
Procedure (105) for performing lapping by moving the lapping tool (1) by the feed mechanism so that the position of the lapping tool (1) with respect to each point on the surface of the workpiece (4) is the feed position. A lapping method comprising: A lapping method according to claim 1,
The lapping tool (1) is a lapping method comprising a protrusion amount adjusting portion (12, 13) for adjusting a protrusion amount of the wrap ball (15) with respect to the attachment portion (11). The lapping method according to any one of claims 1 and 2,
A lapping method, wherein the target shape of the workpiece (4) is a flat surface, and high-precision planar processing is performed. The lapping method according to any one of claims 1 and 2,
A lapping method in which a target shape of the workpiece (4) is an arbitrary three-dimensional curved surface and high-precision three-dimensional curved surface machining is performed. A reciprocating drive unit (3) for reciprocatingly vibrating the lapping tool (1);
An attachment portion (11) for attachment to the reciprocating drive portion (3), a spherical wrap ball (15) made of synthetic resin, and the wrap ball (15) elastically against the attachment portion (11) A lapping tool (1) comprising an elastic support (14) for supporting
A table (25) for mounting the workpiece (4);
A feed mechanism for relatively moving the lapping tool (1) and the table (25) in three axial directions perpendicular to each other;
A controller that controls the feed mechanism to move the lapping tool (1) to a target position;
The controller is
A procedure (102) for determining a lapping machining amount from a difference between measurement data obtained by measuring a machining surface shape of the workpiece (4) and a target shape of the workpiece (4);
A procedure (103) for obtaining a pressing force of the lapping tool (1) on the workpiece to achieve the machining amount under a predetermined machining condition;
A procedure (104) for determining a feed position of the lapping tool (1) for obtaining a pressing force of the lapping tool (1);
Procedure (105) for performing lapping by moving the lapping tool (1) by the feed mechanism so that the position of the lapping tool (1) with respect to each point on the surface of the workpiece (4) is the feed position. A wrapping device that performs the above. A wrapping apparatus according to claim 5, wherein
The lapping tool (1) is a lapping apparatus comprising a projecting amount adjusting portion (12, 13) for adjusting the projecting amount of the wrap ball (15) with respect to the mounting portion (11). The wrapping apparatus according to any one of claims 5 and 6,
The lapping sphere (15) is a wrapping device made of a polyamide-based resin.

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