JP6462348B2 - Thin plate workpiece grinding method - Google Patents

Description

  The present invention relates to a method for grinding a thin plate workpiece, and more particularly to a method for reducing warpage caused by grinding.

  A cutter for cutting spacers, films, metal foils and the like used for high-precision height adjustment is required to be thin (for example, 2 mm or less) and to have a uniform thickness. For this reason, the surface of the thin plate workpiece is ground to obtain spacers and cutters.

  In the grinding step, the thin plate workpiece is held on a table, and both surfaces of the thin plate workpiece are ground with a rotating grindstone. However, this grinding causes a residual stress on the surface of the thin plate workpiece, and the residual stress warps the thin plate workpiece.

In order to reduce this warp, various attempts have been made in the past. For example, when the thin plate workpiece is a magnetic material, paper is sandwiched between the table and the thin plate workpiece, and grinding is performed in a state where the thin plate workpiece is held by an electromagnet provided on the table.
In this method, since the warpage cannot be reduced to a satisfactory level, the warping must be reduced by hitting the final finish with a hammer, which is troublesome.
In recent years, it may be required to reduce warpage to a level that cannot be achieved by the above-described manual work.

Therefore, the following method has also been developed.
In Patent Document 1, the stress generated in the workpiece is released by heating and slow cooling each time grinding is performed.
In Patent Document 2, it is considered that the rotating shaft of the grindstone is bent due to thermal expansion of the work due to frictional heat at the time of grinding, and as a result, distortion occurs on the grinding surface. It is carried out.

Japanese Patent Laid-Open No. 63-200951 Japanese Patent Laid-Open No. 7-148648

  However, the above Patent Documents 1 and 2 have the disadvantages that the work is complicated and the time required to complete grinding is increased.

The present invention has been made to solve the above problems, and in a method of grinding both surfaces of a thin plate workpiece to obtain a desired thickness, the slit forming step is executed before or after the grinding step. Then, a plurality of slits extending in the radial direction are formed in the outer peripheral portion of the thin plate work at intervals in the circumferential direction.
According to this method, warpage caused by grinding due to slit formation can be reduced.
Preferably, the slits are formed at equiangular intervals.

Preferably, a hole is formed in the center of the thin plate workpiece, and in the slit forming step, the plurality of slits are formed as first slits, and a plurality of radially extending inner peripheral portions of the thin plate workpiece are also formed. These slits are formed as second slits at equal angular intervals in the circumferential direction.
According to this method, the effect of reducing warpage can be further exhibited.
More preferably, the second slit is formed so as to be shifted from the first slit in the circumferential direction.

  Preferably, the sum of the length of the first slit, the length of the second slit, and the radius of the hole is smaller than the diameter of the thin plate workpiece, and the thin plate workpiece has an annular shape in which no slit is formed in the radial intermediate portion. Has a region.

In another aspect of the present invention, in a method of grinding both surfaces of a thin plate workpiece having a hole in the center to obtain a desired thickness, a slit forming step is performed before or after the grinding step, and in the slit forming step, A plurality of slits extending in the radial direction are formed in the inner peripheral portion of the thin plate work at intervals in the circumferential direction.
Preferably, the slits are formed at equiangular intervals.

  Preferably, the slit forming step is performed before the grinding step. According to this method, the effect of reducing warpage can be further exhibited.

Preferably, the thin plate workpiece is obtained by slicing a round bar-shaped material by wire electric discharge machining, and the slit is formed by wire electric discharge machining in a state where a plurality of the thin plate workpieces are stacked.
The thin plate workpiece obtained by the slicing has a small warpage before processing. In addition, since the slits are formed by overlapping a plurality of sheets, work efficiency is good.

Preferably, the thin plate workpiece is circular, and the slit has a length corresponding to 5 to 15% of the diameter of the thin plate workpiece.
Preferably, the slits are formed at 8 to 16 locations.
Preferably, the thickness of the thin plate workpiece is 2 mm or less, more preferably 1 mm or less, and the width of the slit is 1 mm or less, more preferably 0.5 mm or less.

  According to the present invention, warpage can be reduced by a relatively simple method without increasing the grinding time.

It is a top view of the thin plate workpiece ground by the method concerning a 1st embodiment of the present invention. It is a side view which shows the grinding process of the same thin-plate workpiece | work, exaggeratingly shows the thickness of a thin-plate workpiece | work. It is a top view of the thin plate workpiece ground by the method concerning a 2nd embodiment of the present invention. It is a top view of the thin plate workpiece ground by the method concerning a 3rd embodiment of the present invention. It is a top view of the thin plate workpiece ground by the method concerning a 4th embodiment of the present invention.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
First, a cylindrical material made of a metal such as stainless steel is quenched, tempered, and annealed, and a hole is formed on the central axis, and then sliced by wire electric discharge machining to obtain a circular shape having a hole 11. A thin workpiece 10 is obtained.

  Next, a plurality of slits 12 are formed at equal intervals in the circumferential direction by wire electric discharge machining on the outer peripheral portion of the thin plate workpiece 10 in a state where a plurality of the thin plate workpieces 10 are stacked. These slits 12 extend in the radial direction. More preferably, it is on a straight line passing through the center of the thin workpiece 10.

  Next, the altered layer (black skin) generated on both surfaces of the thin workpiece 10 by the wire electric discharge machining is removed by surface grinding as shown in FIG. More specifically, the thin plate workpiece 10 is placed on a table 20 having a built-in electromagnet and held by the magnetic force of the electromagnet (magnet chuck). In this holding state, the grindstone 21 is rotated, the table 20 is moved in the X-axis direction (left-right direction in FIG. 2), and further, the Y-axis direction (direction perpendicular to the paper surface) at the position where the thin plate workpiece 10 is separated from the grindstone 21. And then moving in the X-axis direction, and this is repeated to cut a small amount of one surface of the thin plate workpiece 10, and by repeating this many times, the one surface is ground and the altered layer is removed. Next, the thin plate workpiece 10 is inverted, the other surface of the thin plate workpiece 10 is ground in the same manner as described above, and the deteriorated layer is removed.

Next, both surfaces of the thin workpiece 10 are ground in the same manner as described above.
As described above, when the slit 12 is formed, the warpage caused by grinding for removing the deteriorated layer and subsequent grinding can be reduced.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, not only the slits 12 (first slits) are formed on the outer peripheral portion of the thin workpiece 10, but a plurality of second slits 13 are formed at equal intervals in the circumferential direction on the inner peripheral portion. The second slit 13 is also performed by wire electric discharge machining in a state in which a plurality of thin workpieces 10 are stacked.
The second slit 13 extends in the radial direction, and more preferably is on a straight line passing through the center of the thin plate workpiece 10.

The second slit 13 is located at a position shifted from the first slit 12 in the circumferential direction. In the present embodiment, the number of the second slits 13 is the same as the number of the first slits 12, and each second slit 13 is at a central position between the first slits 12 adjacent in the circumferential direction. By forming the second slit 13, the warp of the thin plate workpiece 10 due to grinding could be further reduced.
The number of the second slits 13 may be less than that of the first slits 12, for example, half.

  The sum of the length of the first slit 12, the length of the second slit 13, and the radius of the hole 11 is smaller than the radius of the thin workpiece 10. Thereby, as shown in FIG. 3, the thin plate workpiece 10 has an annular slit non-formation region 15. The width of the region 15 is preferably 15 to 55% of the diameter of the thin workpiece 10 and more preferably 30 to 40%.

  FIG. 4 shows a third embodiment of the present invention. In this embodiment, the hole 11 is not formed in the thin plate workpiece 10. Since others are the same as those of the first embodiment, detailed description thereof is omitted.

In the first to third embodiments, the thin workpiece 10 after grinding can be used as a circular spacer.
You may use the thin-plate workpiece | work 10 of the said 1st, 2nd embodiment as a cutter. In this case, the outer peripheral edge is sharpened. This processing step may be either before or after the slit forming step or the grinding step.

  FIG. 5 shows a fourth embodiment of the present invention. In this embodiment, the thin plate workpiece 10A has a square shape, and a slit 12A is formed at the center of each side of the outer peripheral portion. The formation of the slit 12A is expected to reduce the warp. These slits 12A extend in the radial direction of the inscribed circle of the side of the thin plate workpiece 10A, and are preferably on a straight line orthogonal to the side and passing through the center of the thin plate workpiece 10A.

  The thin plate workpiece may be a regular polygon other than a square. Also in this case, it is preferable to form a slit at the center of each side. When the thin plate workpiece has a hole in the center in the regular polygonal embodiment, the warp reduction effect can be enhanced by forming the second slit in the same manner as in FIG.

  When there is a hole in the center of the thin plate workpiece, a plurality of slits extending in the radial direction may be formed only in the inner peripheral portion of the thin plate workpiece.

In each said embodiment, although the slit was formed before the grinding process, you may form a slit after a grinding process. In this case, although it is inferior to the said embodiment, the curvature reduction effect is acquired.
In each of the above embodiments, the thin plate workpiece is obtained by slicing the material by wire electric discharge machining. However, the thin plate workpiece may be obtained by cutting out the thin plate material by laser processing or the like. Even in this case, although it is inferior to the case of slicing by wire electric discharge machining, a warp reduction effect can be obtained.

Next, the warp reduction effect will be described in more detail based on experimental data.
Comparative Example 1
A cylindrical material of SUS440 with a diameter of 200 mm is quenched, tempered and annealed, and after forming a 50 mm hole in the center, it is sliced by wire electric discharge machining to obtain a thin plate workpiece with a plate thickness of 1.10 mm It was. The amount of warpage of the thin plate workpiece was 0.03 mm.
Next, as described above, grinding for removing the deteriorated layer on both surfaces of the thin workpiece 10 was performed. The depth of cut in this grinding was 3 μm, and each surface was ground by 0.05 mm to a plate thickness of 1.0 mm. The amount of warpage after grinding increased to 0.15 mm.
Next, the main grinding of the thin workpiece 10 was performed. One surface was ground, inverted to the other surface, and further inverted to grind the one surface. The depth of cut in each grinding was 2 μm, and the plate thickness was reduced to 0.91 mm, 0.82 mm, and 0.73 mm for each grinding. The warpage amount increased to 0.60 mm, 1.00 mm, and 1.05 mm at each grinding.

Comparative Example 2
A slit extending in the radial direction having a width of 0.2 mm and a length of 20 mm was formed by wire electric discharge machining at one location on the outer peripheral portion of the thin plate workpiece after the completion of the grinding, but the warpage amount was not changed.

Example 1
When slits were formed at two locations on the outer peripheral portion of the thin plate workpiece after the completion of the grinding, the amount of warpage was 0.80 mm, indicating an improvement.
Example 2
When slits were formed at equal intervals at four locations on the outer peripheral edge of the thin workpiece after the grinding, the amount of warpage was 0.60 mm, and further improvement was observed.
Example 3
When slits were formed at six locations on the outer peripheral edge of the thin plate workpiece after the completion of the grinding, the amount of warpage was 0.20 mm, and further improvement was observed.
Example 4
When slits were formed at equal intervals at 8 locations on the outer peripheral edge of the thin workpiece after completion of the grinding, the amount of warpage was 0.10 mm, and further improvement was observed. The amount of warpage is approximately one tenth of the amount of warpage of 1.05 mm when no slit is formed.

Example 5
Furthermore, when slits (see FIG. 3) having the same dimensions as the slits of the outer peripheral portion were formed at equal intervals at eight locations on the inner peripheral portion of the thin plate workpiece, the amount of warpage could be reduced to 0.025 mm. Thereby, the curvature reduction effect by putting a slit in an inner peripheral part has been confirmed.

Example 6
Prior to the grinding step, the slits were formed at eight locations on the outer periphery of the thin workpiece, and grinding was performed in the same manner as described above. As a result, the amount of warpage after grinding could be set to 0.050 mm. Example 4 It was possible to improve further. Thereby, it has confirmed that the direction which performs a slit formation process before a grinding process can heighten the curvature reduction effect rather than performing it later.

Example 7
Prior to the grinding step, the slits were formed at 8 locations on the outer peripheral portion and the inner peripheral portion of the thin plate workpiece in the same manner as in Example 5, and when grinding was performed, the amount of warpage was reduced to 0.007 mm. I was able to. Thereby, it has confirmed that the case where a slit was formed in both an outer peripheral part and an inner peripheral part prior to a grinding process could exhibit the curvature reduction effect most.

  As shown in the above embodiment, the warp reduction effect can be expected if there are a plurality of slit forming portions, and the warp reduction effect increases as the number of slits is increased, but the number is preferably 6 to 16. This is because even if the number of slit forming portions is further increased, a significant increase in warpage reduction effect cannot be expected, which affects the mechanical strength.

The final thickness of the thin workpiece is preferably 2 mm or less. This is because warpage due to grinding is not noticeable when the thickness exceeds 2 mm.
The width of the slit is preferably as narrow as possible, and is 1 mm or less.
The length of the slit is preferably 10 mm to 30 mm (5 to 15% of the diameter) when the thin plate workpiece has a diameter of 200 mm. This is because if the slit is long, an increase in the warp reduction effect can be expected, but if it exceeds 30 mm, no significant increase in the warp reduction effect can be expected, which affects the mechanical strength.
The present invention is not limited to the above-described embodiments, and various aspects are possible.

  The present invention can be applied to the manufacture of thin spacers and cutters.

10 Thin plate work 11 Hole 12 Slit (first slit)
13 Slit (second slit)
15 Annular region where no slit is formed

Claims (8)

A method of both surfaces of the thin plate work having a hole in the center is ground to a desired thickness,
Performing the slit forming step before or after the grinding step,
In this slit forming step, a plurality of first slits extending in the radial direction are formed in the outer peripheral portion of the thin plate workpiece at equal angular intervals in the circumferential direction, and the inner peripheral portion of the thin plate workpiece is also radially formed. Forming a plurality of second slits extending at equal angular intervals in the circumferential direction;
The sum of the length of the first slit, the length of the second slit, and the radius of the hole is smaller than the radius of the thin plate workpiece, and the thin plate workpiece has a radially inner end of the first slit at a radial intermediate portion thereof. Between the radial outer ends of the second slits, there is a flat annular region where no slit is formed,
The method for grinding a thin plate workpiece, wherein the first slit extends to an outer peripheral edge of the thin plate workpiece, and the second slit extends to an inner peripheral edge of the thin plate workpiece. 2. The method for grinding a thin workpiece according to claim 1 , wherein the second slit is formed so as to be shifted from the first slit in the circumferential direction. In the method to grind both sides of a thin plate workpiece having a hole in the center to the desired thickness,
A slit forming step is performed before or after the grinding step, and in this slit forming step, a plurality of radially extending slits are formed at equal angular intervals in the circumferential direction on the inner peripheral portion of the thin plate workpiece ,
The method for grinding a thin plate workpiece, wherein the slit extends to an inner peripheral edge of the thin plate workpiece. Grinding method of the thin plate work according to any one of claims 1 to 3, characterized in that executing the slit forming step and before the grinding step. The thin plate work, according to claim 1-4, characterized obtain, to form the slit by wire electrical discharge machining the thin plate work in multiple superimposed on one another by slicing the material round bar shape by wire electrical discharge machining The thin plate workpiece grinding method according to any one of the above. The thin plate workpiece according to any one of claims 1 to 5 , wherein the thin plate workpiece has a circular shape and the slit has a length corresponding to 5 to 15% of a diameter of the thin plate workpiece. Grinding method. The method for grinding a thin plate workpiece according to any one of claims 1 to 6 , wherein the slits are formed at 8 to 16 locations. The method for grinding a thin workpiece according to any one of claims 1 to 7 , wherein the thickness of the thin workpiece is 2 mm or less and the width of the slit is 1 mm or less.

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