JP2015030911A - Method for processing dimple - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing dimples, capable of further reducing costs with a lightened workload in comparison with a conventional method and completely eliminating the undesired possibility of particles remaining.SOLUTION: A masking sheet 1 having open holes corresponding to the predetermined positions of fine dimples and an electrode sheet 4 having protrusions 3 corresponding to the respective holes 2 are superimposed such that each of the protrusions 3 is fitted into the midway position of each of the holes 2 to have a predetermined depth. A lining sheet 5 is thus made. In a state that the lining sheet is pressed such that the electrode sheet 4 is opposed to the inner peripheral surface of a cylinder bore 7 (bore) through the masking sheet 1, the gap between the electrode sheet 4 and the inner peripheral surface of the cylinder bore 7 is filled with an electrolyte 9. The side of the electrode sheet 4 makes a negative electrode and a cylinder block 6 (metal component) makes a positive electrode. Due to a direct current flowing between both of the electrodes, the inner peripheral surface of the cylinder bore 7 opposed to each of the protrusions 3 is subjected to electropolishing to form fine dimples 12.

Description

  The present invention relates to a dimple processing method for forming a large number of minute recesses in a regular arrangement on an inner peripheral surface of a cylinder bore or the like in an engine cylinder block.

  In general, the inner peripheral surface of a cylinder bore in an engine cylinder block is subjected to dimple processing for the purpose of improving lubricity. In this type of dimple processing, particles with high hardness ( Many shot blasts that project a projection material) onto a processed surface to form a large number of micro-dents are employed.

  At this time, in order to form the micro dents in a regular arrangement, a cylindrical masking sheet having a hole formed in accordance with the planned position of the micro dents is created and inserted into the cylinder bore. After coating, shot blasting is performed so that a minute depression is formed only in a holed portion.

  The following patent documents 1 and 2 have already been proposed as prior art document information relating to a method of dimple machining the inner peripheral surface of a cylinder bore using this type of shot blasting.

JP 2006-315082 A JP 2010-13993 A

  However, in the conventional method in which dimple processing is performed using shot blasting, there is a problem that the masking sheet that receives the projection of the particles becomes a consumable material and increases the cost, and a large amount of particles remain after processing. In addition, there is a problem in that cleaning for removing such a large amount of particles is necessary and the work load is increased, and the anxiety that particles remain cannot be completely eliminated.

  The present invention has been made in view of the above-mentioned circumstances, and a dimple processing method that can reduce costs and reduce the work load as compared with the prior art and that can completely eliminate the fear of remaining particles. The purpose is to provide.

  The present invention relates to a dimple processing method for forming a large number of minute recesses in a regular arrangement on the inner peripheral surface of a bore formed in a metal member, the holes being drilled in accordance with the positions where the minute recesses are to be formed. A masking sheet and an electrode sheet having a convex portion corresponding to each hole of the masking sheet are inserted into the halfway position of each hole so that the depth of each hole is regulated to a predetermined value. And the inner sheet is pressed against the inner peripheral surface of the bore so that the electrode sheet faces the inner peripheral surface of the bore through the masking sheet. A gap is filled with an electrolytic solution, and a direct current is passed between the electrode sheet side as a cathode and the metal member side as an anode, thereby exposing to a perforated portion of the masking sheet and The inner peripheral surface of the bore that faces the convex portion to be subjected to electrolytic polishing is characterized in that to form the recesses minute.

  In this way, it becomes possible to form a minute recess by electrochemically dissolving the inner peripheral surface of the bore exposed at the perforated portion of the masking sheet and facing each convex portion of the electrode sheet. The masking sheet does not need to be damaged as much as when used for shot blasting, so that the lining sheet composed of the masking sheet and the electrode sheet can be reused, and the cost can be greatly reduced. Moreover, since a large amount of particles does not remain after processing as in the case of using shot blasting, cleaning for removing a large amount of particles is unnecessary, and the work burden is greatly reduced. Makes it possible to completely eliminate the anxiety that particles remain.

  At this time, since the depth of each hole of the lining sheet can be arbitrarily set by the protruding length of the convex portion of the electrode sheet, the depth is equal to the optimum inter-electrode distance for performing the electropolishing. If set, electrolytic polishing can be effectively performed with the distance between the inner peripheral surface of the bore and each convex portion of the electrode sheet as an optimum value.

  Further, in the present invention, it is preferable to immerse the entire metal member in the electrolytic solution and fill the gap between the electrode sheet and the inner peripheral surface of the bore with the electrolytic solution. In this way, the inner periphery of the electrode sheet and the bore A narrow gap between the surfaces can be easily and reliably filled with the electrolytic solution.

  Furthermore, in the present invention, it is preferable to press the lining sheet against the inner peripheral surface of the bore by using a balloon, and in this way, after the inner peripheral surface of the bore is covered with the lining sheet, the balloon is placed inside thereof. It is possible to simply press the lining sheet against the inner peripheral surface of the bore simply by disposing it and expanding it by introducing air.

  According to the dimple processing method of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, since the lining sheet can be repeatedly reused, the cost can be greatly reduced compared to the conventional case, and when shot blasting is used. Thus, since it is not necessary to remove a large amount of particles after processing, it is possible to remarkably reduce the work load, and furthermore, it is possible to completely eliminate the anxiety that particles remain when shot blasting is used.

  (II) According to the invention described in claim 1 of the present invention, the distance between the inner peripheral surface of the bore and each convex portion of the electrode sheet is effective as the optimum inter-electrode distance for performing electrolytic polishing. Since electropolishing can be performed, dimple processing with high productivity can be realized by shortening the processing time as much as possible.

  (III) According to the invention described in claim 2 of the present invention, the entire metal member is immersed in the electrolytic solution, and the space between the electrode sheet and the inner peripheral surface of the bore is filled with the electrolytic solution. It is possible to fill the narrow gap between the inner peripheral surface and the electrolyte solution easily and reliably.

  (IV) According to the invention described in claim 3 of the present invention, after the inner peripheral surface of the bore is covered with the lining sheet, the lining sheet can be simply formed by disposing a balloon inside thereof and inflating it by introducing air. It can be pressed against the inner peripheral surface of the bore.

It is a perspective view of the masking sheet used for the dimple processing method of the present invention. It is a perspective view of the electrode sheet used for the dimple processing method of the present invention. It is sectional drawing of the state which accumulated the masking sheet and the electrode sheet. It is a perspective view of the state where a masking sheet and an electrode sheet were piled up. It is sectional drawing which shows the state which coat | covered the inner peripheral surface of the cylinder bore with the lining sheet. It is the schematic which shows the state which immersed the whole cylinder block in electrolyte solution. It is sectional drawing which shows the state which formed the micro dent by electropolishing.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 7 show an example of an embodiment of the present invention. In the example shown here, dimple processing is performed on the inner peripheral surface of a cylinder bore (bore) in a cylinder block (metal member) of an engine. In this case, a technique as described in detail below is employed so that a large number of dimples can be formed in a regular arrangement on the inner peripheral surface of the cylinder bore.

  That is, in this embodiment, a masking sheet 1 made of a resin having insulation and corrosion resistance that is drilled in accordance with a position where a minute depression is to be formed as shown in FIG. 1, and a masking sheet 1 as shown in FIG. As shown in FIGS. 3 and 4, the conductive electrode sheet 4 having the convex portions 3 corresponding to the respective holes 2 is inserted into the middle positions of the respective holes 2 and the respective convex portions 3 are inserted into the respective positions. One lining sheet 5 is formed by overlapping and integrating the depth 2 of the hole 2 (see FIG. 3) to a predetermined value.

  Then, as shown in FIG. 5, the lining sheet 5 is arranged so that the electrode sheet 4 faces the inner peripheral surface of the cylinder bore 7 in the cylinder block 6 through the masking sheet 1. The inner peripheral surface is covered with the lining sheet 5, and then, as shown in FIG. 6, the entire cylinder block 6 is immersed in the electrolytic solution 9 in the immersion tank 8, and the balloon 10 is arranged inside the lining sheet 5. Then, the lining sheet 5 is pressed against the inner peripheral surface of the cylinder bore 7 by the inflated balloon 10, and even after the pressing, the space between the electrode sheet 4 and the inner peripheral surface of the cylinder bore 7 is the electrolyte solution. 9 to be filled.

  Next, when a direct current from a power source 11 is passed between the electrode sheet 4 side as a cathode and the cylinder block 6 side as an anode, the mask sheet 1 is exposed in a perforated portion as shown in FIG. Then, the inner peripheral surface of the cylinder bore 7 facing the projections 3 of the electrode sheet 4 is subjected to electrolytic polishing to form micro-dents 12 (dimples). A cylinder bore 7 formed on the inner peripheral surface in a regular arrangement is obtained.

  Thus, when the dimple processing is performed as described above, the inner peripheral surface of the cylinder bore 7 exposed to the perforated portion of the masking sheet 1 and facing the convex portions 3 of the electrode sheet 4 is electrochemically applied. It is possible to form the fine recess 12 by dissolving in the resin, and it is not necessary to give the masking sheet 1 such a large damage as in the case of shot blasting. Therefore, the lining sheet 5 comprising the masking sheet 1 and the electrode sheet 4 Can be reused, and the cost can be greatly reduced, and since a large amount of particles do not remain after processing as in the case of shot blasting, The need for cleaning is eliminated, and the work load is greatly reduced. Furthermore, it is possible to completely eliminate the anxiety that particles remain.

  At this time, the depth d (see FIG. 3) of each hole 2 of the lining sheet 5 can be arbitrarily set by the protruding length of the convex portion 3 of the electrode sheet 4, so that the electrolytic polishing is performed. If the depth is set equal to the optimum distance between the electrodes, the electrolytic polishing can be effectively performed with the distance between the inner peripheral surface of the cylinder bore 7 and each convex portion 3 of the electrode sheet 4 as an optimum value. It becomes possible.

  Therefore, according to the above-described embodiment, the lining sheet 5 can be reused repeatedly, so that the cost can be greatly reduced as compared with the prior art, and a large amount of particles after processing as in the case of using shot blasting. Therefore, it is possible to remarkably reduce the work load, and furthermore, it is possible to completely eliminate the anxiety that particles remain, such as when shot blasting is used. Moreover, since the distance between the inner peripheral surface of the cylinder bore 7 and each convex part 3 of the electrode sheet 4 can be effectively electropolished as the optimum inter-electrode distance for performing electropolishing, The dimple processing with high productivity can be realized by shortening the time as much as possible.

  Further, particularly in this embodiment, the entire cylinder block 6 is immersed in the electrolytic solution 9 so that the space between the electrode sheet 4 and the inner peripheral surface of the cylinder bore 7 is filled with the electrolytic solution 9. A narrow gap with the inner peripheral surface of the cylinder bore 7 can be easily and reliably filled with the electrolyte 9, and the lining sheet 5 is pressed against the inner peripheral surface of the cylinder bore 7 using the balloon 10. Therefore, after the inner peripheral surface of the cylinder bore 7 is covered with the lining sheet 5, the lining sheet 5 is simply pressed against the inner peripheral surface of the cylinder bore 7 simply by placing the balloon 10 on the inner side and inflating it by introducing air. Can do.

  The dimple processing method of the present invention is not limited only to the above-described embodiment, and the metal member does not necessarily have to be an engine cylinder block, and the bore formed therein is not necessarily limited to the cylinder bore. Of course, various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Masking sheet 2 Hole 3 Convex part 4 Electrode sheet 5 Liner sheet 6 Cylinder block (metal member)
7 Cylinder bore (bore)
9 Electrolyte 10 Balloon 12 Small depression d Hole depth

Claims (3)

  A dimple processing method for forming a large number of minute depressions in a regular arrangement on the inner peripheral surface of a bore formed in a metal member, and a masking sheet that is drilled in accordance with the formation positions of the minute depressions; The electrode sheet having a convex portion corresponding to each hole of the masking sheet is overlaid so that each convex portion is fitted to the middle position of each hole and the depth of each hole is defined to a predetermined value. An electrolyte solution is provided between the electrode sheet and the inner peripheral surface of the bore in a state where the inner sheet is pressed against the inner peripheral surface of the bore so that the electrode sheet faces the masking sheet. And a direct current is passed between the electrode sheet side as a cathode and the metal member side as an anode, thereby exposing to a perforated portion of the masking sheet and facing each convex portion of the electrode sheet. Dimpled method characterized by relative inner circumferential surface of the bore that is subjected to electrolytic polishing to form a recess micro.   2. The dimple processing method according to claim 1, wherein the entire metal member is immersed in an electrolytic solution, and the space between the electrode sheet and the inner peripheral surface of the bore is filled with the electrolytic solution.   The dimple processing method according to claim 1 or 2, wherein the lining sheet is pressed against the inner peripheral surface of the bore using a balloon.

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