JP2009119544A - Surface working method and rolling member using the working method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface working method capable of continuously forming fine recess parts on the surface of a workpiece by electric discharge. <P>SOLUTION: An electrode 8 of an electrode tool 3 is formed by filling a conductive material 7 into a recess part 6 provided in an insulating film 5 on the surface of a tool body 4, then the electrode tool 3 and a workpiece 1 are relatively moved, so that the electrode 8 of this electrode tool 3 is repeatedly circulated to an electric discharge position. Then, after an electric discharge phenomenon occurs between the electrode 8 of the electrode tool moved to an electric discharge working position A, and the workpiece 1, the electrode 8 of the electrode tool 3 is restored by re-filling the conductive material 7 into the recess part 6 provided in the insulating film 5 on the surface of the tool body 4, in a period while this electrode 8 moves to the electric discharge working position A again by relative movement between the electrode tool 3 and the workpiece 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a mechanical element such as a rolling bearing that realizes friction reduction by a relative motion mainly of rolling, and is particularly suitable for operating conditions such as frequent starting and stopping, swinging motion, or operating conditions such as low speed and high load. The present invention relates to a suitable rolling contact surface processing method.

  In rolling contact parts such as rolling bearings, direct contact of objects is prevented and friction and wear are reduced by using a fluid lubrication state due to the fluid dynamic pressure effect between the objects generated by the relative motion of the objects. can do.

  However, when the amount of lubricating oil is small or when the speed is low, the dynamic pressure effect is small and the lubricating oil film is not formed, and there is a risk of causing solid contact. In particular, in recent years, low-viscosity lubricating oil has been used to reduce torque, and the amount of lubricating oil supplied from the outside has decreased, so the possibility of a solid contact state is even higher. .

  However, even if the amount of lubricating oil in the vicinity of the contact portion is insufficient, lubrication is possible if the surface of the contact portion holds the lubricating oil. Japanese Patent Application Laid-Open No. H10-228688 discloses a technique for retaining lubricating oil in a recess. This technique can improve boundary lubrication performance at low speeds.

  In this patent document 1, the fine recessed part is formed by barrel processing. The formation of the concave portion by barrel processing is also disclosed in Patent Document 2.

  Furthermore, Patent Document 3 discloses that fine irregularities are formed on the surface of a rolling part by barreling after shot blasting.

  Further, Patent Document 4 discloses a metal powder injection molding method in which a recess is formed on a rolling surface of a rolling bearing by mixing a thermoplastic resin and metal powder and allowing the resin to flow out during heat treatment to form a recess. It has been introduced.

  Patent Document 5 introduces the use of a depression on the surface of a ceramic rolling element as a lubricating oil reservoir.

  Patent Document 6 introduces the formation of minute concave portions on the surface by a roller burnishing process in which a roller on which minute convex portions are formed is pressed against the surface of a rolling member.

  Further, Patent Document 7 introduces a method of forming a minute recess on a rolling sliding surface by irradiating a short pulse laser.

  On the other hand, in a plain bearing, a technique is generally used in which lubricating performance is improved by forming a number of grooves having a depth of about the oil film thickness on a sliding surface. This utilizes the fact that a hydrodynamic dynamic pressure action occurs because the depth of the sliding surface changes due to the presence of the groove. An example in which this effect is applied to a rolling bearing is disclosed in Patent Document 8. The technique disclosed in Patent Document 8 attempts to prevent slippage by pressing a rolling element in which a slip occurs at a portion to which a relatively small load is applied against a race ring with a pressure due to a dynamic pressure action. However, the technique of Patent Document 8 is based on the premise that sufficient lubricating oil is supplied to the contact portion from the outside of the contact portion, as in a general hydrodynamic bearing.

  Further, Non-Patent Document 1 discloses an example in which a deep concave portion is provided in a thrust flat plain bearing that supports high surface pressure. This is intended to improve the boundary lubrication performance by discharging the lubricating oil from the recess accompanying thermal expansion. However, this technique is not intended to generate hydrodynamic dynamic pressure effects.

  By the way, the hydrodynamic dynamic pressure action is mainly generated by the viscosity of the fluid, the speed of the contact surface, and the wedge shape of the contact surface. In normal rolling contact, the contact portion of the member is inevitably in the shape of a wedge. Therefore, if a certain viscosity or speed is applied, an oil film is formed and the contact surface is separated.

  However, when trying to increase the dynamic pressure action at low speed, it is difficult to control the viscosity of the fluid, so it is necessary to improve the wedge shape. That is, it is conceivable to increase the dynamic pressure action at a low speed by providing a micro wedge shape on the surface in addition to the macro wedge shape.

  In a rolling bearing, it is considered that oil film formation at low speed is improved by providing a shallow concave portion that generates a dynamic pressure action. However, when the speed is low, supply of lubricating oil from the outside to the contact portion cannot be expected.

  The inventors of the present invention are not allowed to contact the rolling contact portion under operating conditions where frequent starting / stopping operation, rocking motion, or low speed and high load cannot be expected from the outside. By forming a large number of shallow dynamic pressure generating recesses that generate dynamic pressure action due to the presence of lubricating oil, and providing a lubricating oil storage recess deeper than the dynamic pressure generating recess on this dynamic pressure generating surface By supplying lubricating oil from the deep lubricating oil reservoir recess and the dynamic pressure action of the shallow small number of dynamic pressure generating recesses, a sufficient lubricating oil film can be formed even at low speeds, directly It has been found that contact damage can be prevented and surface damage can be prevented by boundary lubrication even at extremely low speeds.

  In order to embody this knowledge, it is important to provide recesses with different sizes and depths at the rolling contact portion with high accuracy. However, in the above conventional processing method, the size and depth of the opening surface of the recesses are important. There is a problem that it is difficult to arbitrarily control the thickness in the order of μm, or unnecessary convex portions are generated around the processed portion.

As a method for solving such a problem, it is conceivable to employ a surface processing method by electric discharge machining.
In electric discharge machining, concave portions whose sizes, depths, and positions are controlled to the order of μm can be provided with good reproducibility, and projections and the like are hardly generated around the concave portions. Furthermore, it is possible to provide recesses having different sizes, depths, and positions on the same surface by performing electric discharge machining on the same surface a plurality of times, which is an advantageous method for solving the above problem. .

However, in the electric discharge machining, since the electrode as a tool is worn, it is necessary to repair it. Regarding the restoration of this electrode, there are technologies disclosed in Patent Document 9 and Patent Document 10.
However, these electrode repair methods are not suitable for mass production because continuous electrical discharge machining cannot be performed because the machining must be temporarily stopped for repair.

Japanese Patent Laid-Open No. 02-168021 JP 05-288221 A Japanese Patent Application Laid-Open No. 08-232964 Japanese Patent Laid-Open No. 10-227313 JP 2000-205267 A JP 2004-116766 A JP-A-2005-32148 JP 2006-105361 A JP-A-11-309626 JP 2005-509533 A H.Kotera, A.Mori, N.Tagawa, PROPOSAL OF A SEIZURE PREVENTING METHOD IN HEAVILY LOADED SLIDING PAIRS, Synopses of the International Tribology ConferenceKobe, 2005, D-04

  Accordingly, the present invention provides a surface processing method capable of continuously forming fine recesses on the surface of a workpiece by electric discharge machining so that the electrode can be repaired without stopping electric discharge machining. It is what.

  The present invention applies electrical energy between the electrode tool and the workpiece, and transfers the electrode shape of the electrode tool to the workpiece by a discharge phenomenon between the electrode of the electrode tool and the workpiece. In the surface machining method using electric discharge machining that forms a recess on the surface of the electrode, the electrode of the electrode tool is formed by filling the recess provided in the insulator film on the surface of the tool body with a conductive material, and this electrode tool electrode The electrode tool and the workpiece are moved relative to each other so as to repeatedly circulate to the electric discharge machining position, and the electrode of the electrode tool moved to the electric discharge machining position generates an electric discharge phenomenon with the workpiece. The conductive material is refilled in the recesses provided in the insulator film on the surface of the tool body until the electrode tool and workpiece are moved to the electric discharge machining position again due to relative movement between the electrode tool and the workpiece. The electrode is repaired.

As the material for the insulator film on the surface of the tool body, various resins and ceramics can be used.
The insulator film is provided with a recess for forming an electrode. The shape of the recess corresponds to the shape of the recess formed on the surface of the workpiece. The concave portion of the insulator film is filled with a conductive material, and the filled conductive material functions as an electrode. A large number of these electrodes are continuously provided on the surface of the tool body. By relatively moving the tool body and the workpiece, the electrodes provided on the tool body move one after another to the electric discharge machining position, and the workpiece is processed. Electrical discharge machining was continuously performed between the workpieces.

  The electrode tool and the workpiece are controlled so as to move relative to each other so that the electrode of the electrode tool repeatedly circulates to the electric discharge machining position, and the electrode of the electrode tool moved to the electric discharge machining position is discharged between the workpiece and the workpiece. After the phenomenon occurs, the electrode is moved again to the electric discharge machining position by the relative movement between the electrode tool and the workpiece.

  Then, during the process until the electrode worn by the electric discharge machining moves again to the electric discharge machining position, the electrode material of the electrode tool is refilled with a conductive material in the recess provided in the insulator film on the surface of the tool body. I tried to repair it.

  As a method for refilling the conductive material, the conductive powder is supplied to the worn portion of the electrode filled in the concave portion provided in the insulator film, and the conductive powder is compressed by a compression roller to fill the concave portion. A method of scraping off excess conductor powder adhering to the surface of the insulator film of the main body with a scraper can be employed. By this method, since the worn electrode is repaired before the worn electrode moves to the electric discharge machining position again, the electric discharge machining is continuously performed without stopping the electric discharge machining when the electrode is repaired. be able to.

As described above, according to the present invention, it is possible to continuously repair an electrode that performs electric discharge machining without stopping electric discharge machining, so that fine concave portions are continuously formed on the surface of the workpiece. Can do.
Therefore, when the surface processing method of the present invention is used, fine concave portions can be accurately and efficiently processed by electric discharge machining on the surface of the rolling / sliding member, the rolling element of the rolling bearing, and the inner and outer rings. it can.

FIG. 1 shows an example of the surface processing method of the present invention in which minute concave portions 2 are formed on the surface of a cylindrical workpiece 1 such as a roller by electric discharge machining.
The electrode tool 3 used in the example of FIG. 1 includes a cylindrical tool body 4 formed of a conductor such as metal, an insulator film 5 provided on the surface of the tool body 4, and an insulator film 5 It consists of an electrode 8 formed by filling the provided recess 6 with a conductor powder 7. A large number of the electrodes 8 are provided on the outer peripheral surface of the tool body 4 at a predetermined interval.

  The electrode tool 3 and the cylindrical workpiece 1 rotate in opposite directions with parallel rotation axes, and an insulating oil is interposed between the electrode tool 3 and the workpiece 1 so that the electrode tool 3 and the workpiece 1 are processed. Due to the DC voltage applied between the workpiece 1 and the electrode tool 3 and the cylindrical workpiece 1, the discharge phenomenon occurs at the closest position (A in FIG. 1). Due to this discharge phenomenon, the shape of the electrode 8 of the electrode tool 3 is transferred to the surface of the workpiece 1, the concave portion 2 corresponding to the shape of the electrode 8 is formed on the surface of the workpiece 1, and the electrode 8 is consumed. For discharge, pulse discharge using a capacitor, a transistor, or the like can be used, and the processing depth of the recess 2 can be controlled by controlling the discharge voltage.

  The electrode tool 3 and the workpiece 1 are rotated so that the peripheral speeds coincide with each other in opposite directions, and the electrodes 8 on the peripheral surface of the electrode tool 3 are repeatedly circulated one after another to the electric discharge machining position. . The electrode 8 is consumed due to the discharge phenomenon, and the electrode 8 is recessed.

  The dent of the consumed electrode 8 is backfilled with the conductor powder 7 and repaired while the consumed electrode 8 returns to the electric discharge machining position. In this backfilling, the conductive powder 7 is supplied to the worn portion of the electrode 8 filled in the concave portion 6 provided in the insulator film 5, and the conductive powder 7 is compressed by the compression roller 9 to be conductive in the concave portion 6. The body powder 7 is packed, and the excess conductor powder 7 adhering to the surface of the insulator film 5 of the tool body 4 is scraped off by the scraper 10.

  After the workpiece 1 is rotated once and the machining is completed, a new workpiece 1 is set and the electric discharge machining is repeated. As described above, electric discharge machining can be continuously performed while repairing the electrode 8.

  Next, (a), (b), and (c) of FIG. 2 are surface processing methods using the plate-like electrode tool 3, and the processing principle is the same as the example of FIG.

  In the example of FIG. 2, the electrode tool 3 includes a plate-like tool body 4 formed of a conductor such as metal, an insulator film 5 provided on the surface of the tool body 4, and the insulator film 5. The electrode tool 3 is reciprocated and the cylindrical workpiece 1 is rotated relative to the reciprocating electrode tool 3 to reciprocate the electrode tool 3. The electrode 8 of the electrode tool 3 is repeatedly circulated to the electric discharge machining position A by the movement and the rotational movement of the workpiece 1.

  The repair of the worn electrode 8 is performed by setting the plate-shaped electrode tool 3 to the position shown in FIG. Then, as shown in FIG. 2A, the conductor powder 7 is supplied to the worn portion of the electrode 8 filled in the recess 6 provided in the insulator film 5, and the conductor powder 7 is supplied to the compression roller 9 as shown in FIG. In this method, the conductive powder 7 is packed in the concave portion 6 and the conductive powder 7 attached to the surface of the insulator film 5 of the tool body 4 is scraped off by the scraper 10.

  And the new workpiece 1 can be processed continuously by repeating the process of (a), (b), (c) of FIG.

  Next, FIGS. 3A and 3B show an example in which a minute recess 2 is formed on the inner diameter surface of the annular workpiece 1, and the processing principle is shown in FIG. 1 and FIG. This is basically the same as the example.

  In this example, a cylindrical electrode tool 3 is inserted inside an annular workpiece 1, and the electrode tool 3 is reciprocated while rotating, and the annular workpiece 1 is moved with respect to the electrode tool 3. , The minute recesses 2 are formed on the inner diameter surface of the annular workpiece 1 by electric discharge machining.

  In this example, the scraper 10 has an axisymmetric shape and is in contact with the electrode 8 on the circumference. For example, when it is desired to dispose the recesses 2 on the same circumference on the inner diameter surface of the workpiece 1, the pattern of the recesses 6 on the insulator film 5, that is, the pattern of the electrodes 8, depends on the feed rate of the electrode tool 3 What is necessary is just to arrange | position so that it may twist with a pitch.

  Next, FIG. 4 is an example in which a minute concave portion 2 is formed on the surface of a roller of a cylindrical roller bearing using the surface processing method of the present invention. The surface processing method of the present invention is particularly suitable for such a cylindrical surface. It is suitable for processing. In FIG. 4, reference numeral 11 denotes a cylindrical roller, 12 denotes an outer ring, 13 denotes an inner ring, and 14 denotes a cage. The minute recess 2 is shown by a black circle on the surface of the cylindrical roller 12.

  In the surface processing method of the present invention, the insulator film 5 is provided on the surface of the tool body 4, the recess 6 for filling the insulator film 5 with the conductive material is formed, and the conductive material filled in the recess 6 becomes the electrode 8. An electrode tool 3 is used. Therefore, since the shape and arrangement of the electrode 8 can be arbitrarily set, by repeating electric discharge machining using the electrode tool 3 having a different pattern of the electrode 8, concave portions having different sizes, depths, and positions can be formed on the same surface. It is possible to provide easily, and it is possible to easily provide a deep concave portion for supplying lubricating oil and a shallow concave portion for generating a dynamic pressure action on the surface of the rolling / sliding member.

  Further, by combining etching processing, laser processing, or the like different from the surface processing method of the present invention with the surface processing method of the present invention, different types of recesses can be formed on the surface of the roller or inner ring of the cylindrical roller bearing. Furthermore, it is applicable not only to a cylindrical roller bearing but also to other rolling bearings.

It is a conceptual diagram which shows an example of the surface processing method of this invention. (A) (b) (c) is a conceptual diagram which shows the other example of the surface processing method of this invention. (A) (b) is a conceptual diagram which shows the other example of the surface processing method of this invention. It is the schematic of the cylindrical roller bearing to which the surface processing method of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Workpiece 2 Recess 3 Electrode tool 4 Tool body 5 Insulator film 6 Recess 7 Conductor powder 8 Electrode 9 Compression roller 10 Scraper

Claims (8)

  By applying electric energy between the electrode tool and the work piece, the electrode tool's electrode shape is transferred to the work piece by the discharge phenomenon between the electrode tool and the work piece, and the surface of the work piece is recessed. In the surface machining method using electric discharge machining, the electrode of the electrode tool is formed by filling a recess provided in the insulator film on the surface of the tool body with a conductive material, and the electrode of the electrode tool is positioned at the electric discharge machining position. The electrode tool and the workpiece are moved relative to each other so as to circulate repeatedly, and the electrode tool moved to the electric discharge machining position generates an electric discharge phenomenon between the electrode tool and the electrode tool. The electrode tool of the electrode tool is repaired by refilling the recess provided in the insulator film on the surface of the tool body with the conductive material until it moves to the electric discharge machining position again due to relative movement with the workpiece. A surface processing method characterized by the above.   The electrode tool includes a cylindrical tool body, an insulator film provided on the surface of the tool body, and an electrode made of a conductive material filled in a recess provided in the insulator film. 2. The surface machining method according to claim 1, wherein the workpiece is rotated and the electrodes of the electrode tool are repeatedly circulated to the electric discharge machining position by the rotation of the electrode tool and the workpiece.   The electrode tool comprises a plate-shaped tool body, an insulator film provided on the surface of the tool body, and an electrode of a conductive material filled in a recess provided in the insulator film. The electrode tool is reciprocated, The cylindrical workpiece was rotated with respect to the reciprocating electrode tool, and the electrode tool electrode was repeatedly circulated to the electrical discharge machining position by the reciprocating motion of the electrode tool and the rotational motion of the workpiece. The surface processing method according to claim 1.   The electrode tool comprises a cylindrical tool body, an insulator film provided on the surface of the tool body, and an electrode made of a conductive material filled in a recess provided in the insulator film. Insert inside the workpiece, reciprocate while rotating this electrode tool, rotate the annular workpiece against the rotating / reciprocating electrode tool, and rotate and reciprocate the electrode tool. 2. The surface machining method according to claim 1, wherein the electrode of the electrode tool is repeatedly circulated to the electric discharge machining position by the rotational movement of the workpiece.   5. Surface processing for performing electrical discharge machining according to claims 1 to 4 using a plurality of electrode tools having different electrode shapes, and forming recesses having different sizes, depths, and positions on the surface of the same workpiece. Method.   A surface machining method for forming recesses having different sizes, depths, and positions on the surface of the same workpiece by combining the electric discharge machining according to claim 1 and another surface machining method different from electric discharge machining.   A rolling / sliding member having a fine recess formed on the surface by the surface processing method according to claim 5 or 6.   The rolling bearing which formed the fine recessed part in the at least one surface of the rolling element and the inner and outer ring | wheels by the surface processing method of Claim 5 or 6.

Images