JP2014008558A - Method and apparatus for correcting electrodeposition grindstone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct an electrodeposition grindstone with high accuracy, even if the rigidity of a shank holding abrasive particles is low, by reducing correction resistance of the electrodeposition grindstone.SOLUTION: A method of correcting an electrodeposition grindstone 13 includes a truing step of relatively reciprocating a truer and an abrasive grain layer in an axial direction of a shank, while bringing the truer 32 rotated around a predetermined axis into abutment with the abrasive grain layer 52 in the electrodeposition grindstone 13 rotated around the shank 51. The abutment part of the truer to the abrasive grain layer serves as an annular corner 42a formed in the rotating direction of the truer, and the truer is brought ino point contact with the electrodeposition grindstone.

Description

  The present invention relates to a correction method and a correction device for reshaping or sharpening an electrodeposition grindstone, and more particularly to a correction method and a correction device suitable for an electrodeposition grindstone used for internal grinding of a small diameter hole.

  Conventionally, as a method of correcting an electrodeposited grindstone holding diamond abrasive grains, for example, while rotating the electrodeposited grindstone, the surface of the abrasive grains is increased by truing with a truing roll that rotates around an axis parallel to the rotation axis. Also known is to reduce the grinding resistance of the workpiece (workpiece) by crushing the surface layer part of the abrasive grains with a crushing roll that rotates around a parallel axis in the same way. (See Patent Document 1).

Japanese Patent Laid-Open No. 5-50378

  By the way, in the electrodeposition grindstone used for internal grinding of small-diameter holes such as those provided in miniature bearing races, etc., relatively small-diameter abrasive grains are used, and the shank (base metal) that holds the abrasive grains is also compared. A small diameter (for example, 3 mm in diameter). Since such a shank is a cantilever and has low rigidity, the method of correcting the rotating truing roll or the like simply by contacting the electrodeposition grindstone as in the prior art described in Patent Document 1 There has been a problem that the correction resistance (and hence the accuracy of the internal grinding process) is lowered due to the deflection of the shank caused by the correction resistance. Moreover, in the said prior art, since it was necessary to use two rolls (truing roll and crushing roll) for correction of an electrodeposition grindstone, there also existed a problem that an apparatus became complicated.

  In addition, the number of effective cutting edges decreases as the diameter of an electrodepositing grindstone decreases. For example, an electrodeposited grindstone having a diameter of 3 mm has only one or two effective cutting edges on the same circumference, and therefore the finished surface is rough. It can be said that this is a feature of the electrodeposition grindstone.

  The present invention has been devised in view of such problems of the prior art. By reducing the correction resistance of the electrodeposition grindstone, high-precision correction is achieved even when the rigidity of the shank holding the abrasive grains is low. It is a main object of the present invention to provide an electrodeposition grindstone correction method and an electrodeposition grindstone correction device that enable the above.

  According to a first aspect of the present invention, there is provided a method for correcting an electrodeposited grindstone (13) in which an abrasive grain layer (52) is formed on an outer periphery on one end side of a cylindrical shank (51), and the method is provided around an axis of the shank. In a state where the correction tool (32) rotated around a predetermined axis is in contact with the abrasive layer in the rotated electrodeposition grindstone, the correction tool and the abrasive layer are brought into contact with the shank. A correction step of reciprocating relatively in the axial direction, and the contact portion of the correction tool with respect to the abrasive layer is an annular corner portion (42a) formed along the rotation direction of the correction tool. ).

  In the method for correcting an electrodeposition grindstone according to the first aspect, an annular corner portion of the rotated correction tool is brought into contact with the abrasive layer of the electrodeposition grindstone (that is, substantially point contact). The resistance of the electrodeposition grindstone can be reduced. As a result, even when the rigidity of the shank holding the abrasive grains is low, like the electrodeposition grindstone used for internal grinding of small-diameter holes, high-precision correction is possible. It becomes.

  In the second aspect of the present invention, with respect to the first aspect, the correction tool has a cylindrical part (41a) formed at least on one end side thereof, and the corner part is in the cylindrical part. It forms the connection part of an outer peripheral surface and an end surface.

  In the method for correcting an electrodeposition grindstone according to the second aspect, the correction tool and the abrasive layer of the electrodeposition grindstone are substantially point-contacted in the correction step without complicating the configuration of the correction tool or the correction device. It becomes possible to make it.

  According to a third aspect of the present invention, with respect to the first or second aspect, in the correcting step, the corner portion is separated from the shank by a distance (G) equal to an average particle diameter of abrasive grains constituting the abrasive grain layer. It is characterized by being separated from the outer peripheral surface of the.

  In the method for correcting an electrodeposited grindstone according to the third aspect, it is possible to accurately adjust the cutting edge height of the abrasive grains in the abrasive layer while reducing the correction resistance.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, a ratio of a peripheral speed of the correction tool to a peripheral speed of the electrodeposition grindstone is 0.8. .

  In the method for correcting an electrodeposition grindstone according to the fourth aspect, the surface shape of the abrasive layer is optimized, and as a result, the surface roughness of the workpiece during grinding with the electrodeposition grindstone can be reduced.

  According to a fifth aspect of the present invention, there is provided a correction device (1) for an electrodeposited grindstone (13) in which an abrasive grain layer (52) is formed on an outer periphery on one end side of a cylindrical shank (51), A grindstone base (15) for holding the grinding stone rotatably around the shank axis, a grindstone table (16) for supporting the grindstone base so as to be movable in the axial direction of the shank, and a correction tool around the axis And a tool table (12) that supports the tool support movably in a direction orthogonal to the axial direction of the shank, and the shank shaft and the correction The correction tool is arranged in a direction intersecting with the axis of the tool, and the correction tool has a cylindrical portion (41a) formed at least on one end side thereof, and the end surface and the outer peripheral surface of the cylindrical portion are connected to each other. An annular corner (42a) forming the part Characterized in that it abuts against the abrasive layer.

  In the electrodeposition grindstone correcting apparatus according to the fifth aspect, the annular corner portion of the columnar portion of the rotated correction tool is brought into contact with the abrasive layer of the electrodeposition grindstone. The correction resistance of the electrodeposition grindstone can be reduced without complicating the configuration of the apparatus. As a result, the rigidity of the shank holding the abrasive grains as in the electrodeposition grindstone used for internal grinding of small diameter holes can be reduced. Even if it is low, high-precision correction is possible.

  As described above, according to the present invention, by reducing the correction resistance of the electrodeposition grindstone, there is an excellent effect that high-precision correction is possible even when the rigidity of the shank holding the abrasive grains is low.

It is a principal part top view of the correction apparatus used for the correction method of the electrodeposition grindstone which concerns on this invention. It is a figure which shows arrangement | positioning of a truer and an electrodeposition grindstone in the correction apparatus shown in FIG. It is typical sectional drawing which shows the structure of an electrodeposition grindstone. It is explanatory drawing which shows the truing process by the correction apparatus shown in FIG. It is a figure which shows the modification of arrangement | positioning with the truer and electrodeposition grindstone shown in FIG. It is a figure which shows the truing result (comparison of the surface profile of an abrasive grain layer) by the correction apparatus shown in FIG. 1 ((A) After truing, (B) Before truing). It is a figure which shows the truing result (SEM photograph of the surface of an abrasive grain layer) by the correction apparatus shown in FIG. It is a figure which shows the grinding result (relationship of the number of oscillations and surface roughness) by the electrodeposition grindstone after truing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description, the term indicating the direction follows the direction indicated by the arrow in FIG.

  First, with reference to FIGS. 1-3, the structure of the correction apparatus 1 of the electrodeposition grindstone which concerns on this invention is demonstrated. This correction device 1 has a configuration in which a truing device 3 is attached to an internal grinding machine 2. The internal grinding machine 2 has a well-known configuration, and is driven by a motor (not shown) to hold a worktable W rotatably, and a work table (supporting a main table 11 movably in the left-right direction). (Tool table) 12, a grindstone table 15 for holding the electrodeposition grindstone 13 rotatably by a spindle motor 14, and a grindstone table 16 for supporting the grindstone table 15 movably in the front-rear direction.

  In the internal grinding machine 2, the workpiece W is fixed to the spindle of the spindle stock 11 via the chuck 21. The work table 12 is provided on the first bed 25 so as to be movable along a guide rail 26 extending in the left-right direction. Further, the grindstone table 16 is provided on the second bed 27 so as to be movable along the guide rail 28 extending in the front-rear direction, whereby the electrodeposited grindstone 13 is in the front-rear direction which is the axial direction thereof. Can be moved to.

  The truing device 3 includes a support plate 31 fixed to the right rear portion of the work table 12 and a truer base (tool support) which is attached to the support plate 31 and rotatably holds a truer (correcting tool) 32 by a spindle motor 33. Stand) 34. The truing device 3 is movable in the left-right direction together with the work table 12.

  As shown in FIG. 2, the truer 32 includes a metal shaft portion 41 having a relatively small diameter (here, an outer diameter of 7 mm) and a cutting edge portion 42 provided at the tip of the shaft portion 41. Have. The distal end portion (columnar portion) 41a of the shaft portion 41 is slightly enlarged in diameter, and a blade edge portion 42 having a disk shape with the same diameter is brazed to the end face of the distal end portion 41a. The cutting edge portion 42 is formed of PCD (Polycrystalline Diamond) having higher hardness than the abrasive grains of the electrodeposition grindstone 13 to be described in detail later. Diamond, PVD (Nano-Polycrystalline Diamond), DLC (Diamond-Like Carbon), etc. can be used.

  The truer 32 and the electrodeposition grindstone 13 are held in the correcting device 1 (see FIG. 1) so that their center positions are the same height. Further, the axial direction of the truer 32 (see the axis C1 in FIG. 2) is arranged so as to intersect the axial direction of the electrodeposition grindstone 13 (see the axis C2 in FIG. 2). Here, the crossing angle θ between the axis C1 and the axis C2 is set to 45 °. Due to the arrangement of the truer 32 and the electrodeposition grindstone 13, in the truer 32, an annular corner 42 a that forms a connecting portion between the outer peripheral surface and the end face of the tip portion 41 a (blade edge portion 42) is formed on the electrodeposition grindstone 13. It can come into contact with each other.

  The crossing angle θ is not limited to 45 °, and can be changed as long as the truer 32 and the electrodeposition grindstone 13 can be substantially brought into point contact. However, when the crossing angle θ is set to a very small angle (for example, 5 ° or less), substantial point contact may be impaired. Therefore, a relatively large angle (for example, 20 ° or more) is preferable. Moreover, it is preferable that the angle (angle in the cross section which passes along the axis C1 of the electrodeposition grindstone 13) of the corner | angular part 42a is 90 degrees or less.

  The electrodeposition grindstone 13 is formed on a metal shank (base metal) 51 having a relatively small diameter (here, 3 mm in outer diameter) and a predetermined axial length on the outer periphery on the tip side of the shank 51. And an abrasive layer 52 formed. As shown in FIG. 3, the abrasive grain layer 52 is provided on a base plating layer 53 formed on the outer peripheral surface of the shank 51, and a plurality of abrasive grains 54 are sequentially laminated on the base plating layer 53. It is fixed by the electrolytic plating layer 55 and the electroless plating layer 56. In the abrasive grain layer 52, a plurality of abrasive grains 54 are arranged in a single layer, and the lower part of the abrasive grain 54 abuts the base plating layer 53, while the upper part of the abrasive grain 54 is outward from the surface of the electroless plating layer. It protrudes. Although the abrasive grains 54 are formed of CBN (Cubic Boron Nitride), the present invention is not limited thereto, and known superabrasive grains such as synthetic diamond can be used. The grain size of the abrasive grains 54 is 80/100 (JIS B 4130) based on the opening size of the sieve, and the average grain size is 177 μm.

  Next, with reference to FIG. 4, the truing process (correction process) of the electrodeposition grindstone 13 by the correction apparatus 1 will be described. As a pre-process of the truing process, the internal grinding machine 2 uses the electrodeposition grindstone 13 before truing (before correction) with the grindstone table 16 shown in FIG. The rough grinding step is performed. After the rough grinding process is completed, the truing device 3 can perform the truing process by moving the work table 12 leftward to the predetermined position while retracting the grindstone table 16 to the predetermined position (the right side of the electrodeposition grindstone 13). Toward the side).

  In the truing process, as shown in FIG. 4A, the initial position of the truer 32 is determined by abutting the corner 42 a of the truer 32 against the outer peripheral surface of the shank 51 of the electrodeposition grindstone 13. Subsequently, as shown in FIG. 4B, the corner 42 a is separated from the outer peripheral surface of the shank 51 by a predetermined gap G. This interval G can be set according to the size of the abrasive grains 54 (the amount of protrusion from the outer peripheral surface of the shank 51), and in particular, it may be set to the same size as the average grain size of the abrasive grains 54. . Thereby, it is possible to accurately adjust (homogenize) the protruding amount (cutting edge height) of the abrasive grains 54 in the abrasive grain layer 52 while reducing the truing resistance (correction resistance).

  Next, while maintaining the gap G, as shown in FIG. 4C, the corner portion 42a of the rotating truer 32 was brought into contact with the surface of the abrasive grain layer 52 of the rotating electrodeposition grindstone 13. In this state, the truer 32 and the electrodeposition grindstone 13 (abrasive layer 52) are repeatedly relatively moved in the axial direction of the shank 51. More specifically, the reciprocating movement (oscillation) of the electrodeposition grindstone 13 in the front-rear direction is performed a plurality of times (here, 10 times) in a state where the position of the rotating truer 32 is fixed. At this time, the upper end portion of the abrasive grain 54 in contact with the corner portion 42a of the truer 32 is cut, thereby adjusting the shape of the surface of the abrasive grain layer 52 and sharpening the upper end portion of the abrasive grain 54 (small unevenness). Is formed).

  Then, in the correction apparatus 1, the finish grinding process using the electrodeposition grindstone 13 after truing is implemented as a post process of a truing process. That is, in the correction apparatus 1, the rough grinding process and the finish grinding process can be performed using the same electrodeposition grindstone 13 through the truing process.

  Note that the structure of the truer 32 is not limited to the above-described one, and various modifications can be made as long as it can substantially make point contact with the electrodeposition grindstone 13 at least in a rotating state. For example, as shown in FIG. 5, the axial direction of the truer 32 (see the axis C <b> 1 in FIG. 5) is arranged in parallel to the axial direction of the electrodeposition grindstone 13 (see the axial line C <b> 2 in FIG. 5). The tip portion 41a can be made into an abacus bead shape (a shape in which the bottom portions of two truncated cones are connected). In this case, the blade edge portion 42 forms the outer peripheral edge portion of the maximum diameter portion (the connection portion of the bottom portion of the truncated cone) of the tip portion 41a, and an annular corner portion 42a is formed at the outer peripheral end thereof.

  Hereinafter, with reference to FIGS. 6 to 8, the truing result by the correcting device 1 having the above-described configuration and the grinding result of the workpiece W by the electrodeposition grindstone 13 after truing will be described with reference to more specific examples. Regarding truing conditions, grinding conditions, and the like, matters not particularly mentioned below are the same as those described above.

  Table 1 shows truing conditions in the examples. Here, the peripheral speed ratio is a ratio of the peripheral speed of the truer 32 to the peripheral speed of the electrodeposition grindstone 13 (peripheral speed of the truer 32 / peripheral speed of the electrodeposited grindstone 13), and has three stages (0.4, 0.8, 1.25). The truing process was carried out by switching to. Further, the surface profile of the abrasive layer 52 shown in FIG. 6 was measured by attaching a knife edge stylus to a surface roughness meter.

  In the surface profile of the abrasive grain layer 52 after truing (circumferential speed ratio 0.8) shown in FIG. 6 (A), the surface is obtained by making the cutting edge height uniform compared to before truing shown in FIG. 6 (B). It can be confirmed that the shape is well adjusted and fine irregularities are formed on the upper surface of the abrasive grains 54. Furthermore, it can also be confirmed that a larger-sized recess (chip pocket) is formed between these fine irregularities. More specifically, as shown in FIG. 7, on the upper surface of the abrasive grains 54, fine irregularities having a depth of about 5 μm considered to have occurred due to brittle fracture in the truing process are formed. Is about 20 μm. When the peripheral speed ratio was 0.8, the truing resistance (normal direction) measured with a Kistler three-component dynamometer was 0.07N.

  Table 2 shows the grinding conditions in the examples.

  As shown in FIG. 8, the surface roughness (arithmetic average roughness) Ra of the workpiece W after grinding is 0.15 μm or less for all the circumferential speed ratios in the truing process, and particularly in an electrodeposition grindstone with a circumferential speed ratio of 0.8. Minimum (0.08 μm). The grinding resistance (normal direction) was 1.13, 0.25, and 0.48 N for the electrodeposition grindstones with a peripheral speed ratio of 0.4, 0.8, and 1.25, respectively. In other words, the truing process is most preferably performed at a peripheral speed ratio of 0.8, whereby the surface shape of the abrasive grain layer 52 is optimized, and as a result, the surface roughness of the workpiece during grinding with the electrodeposited grindstone 13 is reduced. Can be reduced.

  As described above, in the truing method (correcting method) and the correcting device for the electrodeposited grindstone according to the present invention, the annular corner 42a of the rotated tourer 32 is brought into contact with the abrasive layer 52 of the electrodeposited grindstone 13. Therefore, the truing resistance during truing of the electrodeposition grindstone 13 can be reduced, and as a result, the electrodeposition grindstone used for internal grinding of a small-diameter hole cantilevered. Even in the case of a low-stiffness shank that forms a beam, high-precision correction is possible by suppressing deflection. Further, in the truing process, not only the shape adjustment of the surface of the abrasive layer 52 but also the sharpening of the upper end of the abrasive grain 54 (formation of minute irregularities) can be performed, so that subsequent steps such as sharpening are unnecessary. It is.

  Although the present invention has been described based on specific embodiments, these embodiments are merely examples, and the present invention is not limited to these embodiments. For example, the electrodeposition grindstone correcting device according to the present invention can be configured separately from the internal grinding machine 2. The structure of the electrodeposition grindstone is not limited to that described above, and other known configurations can be employed. The components of the electrodeposition grindstone correction method and electrodeposition grindstone correction device according to the present invention shown in the above embodiments are not necessarily all essential, and are appropriately discarded as long as they do not depart from the scope of the present invention. It is possible to select.

DESCRIPTION OF SYMBOLS 1 Correction apparatus 2 Internal grinding machine 3 Truing apparatus 11 Headstock 12 Work table (tool table)
13 Electrodeposition grindstone 15 Grinding wheel base 16 Grinding wheel table 32 Truer (tool for correction)
34 Tsurure stand (tool support stand)
41 Shaft part 41a Tip part (columnar part)
42 Cutting Edge 42a Corner 51 Shank 52 Abrasive Grain Layer 54 Abrasive G Gap

Claims (5)

A method for correcting an electrodeposited grindstone in which an abrasive layer is formed on the outer periphery on one end side of a cylindrical shank,
In a state where the correction tool rotated around a predetermined axis is in contact with the abrasive layer in the electrodeposition grindstone rotated around the shank axis, the correction tool, the abrasive layer, A reciprocating process relatively reciprocating in the axial direction of the shank,
The method for correcting an electrodeposited grindstone, wherein the contact portion of the correction tool with respect to the abrasive layer is an annular corner formed along the rotation direction of the correction tool. The correction tool has a cylindrical portion formed on at least one end thereof;
The method for correcting an electrodeposited grindstone according to claim 1, wherein the corner portion forms a connection portion between an outer peripheral surface and an end surface of the cylindrical portion.   3. The electric power according to claim 1, wherein, in the correcting step, the corner portion is separated from the outer peripheral surface of the shank by a distance equal to an average particle diameter of abrasive grains constituting the abrasive grain layer. How to correct the grinding stone.   The method of correcting an electrodeposition grindstone according to any one of claims 1 to 3, wherein a ratio of a peripheral speed of the correction tool to a peripheral speed of the electrodeposition grindstone is 0.8. An electrodeposition grindstone correction device in which an abrasive grain layer is formed on the outer periphery on one end side of a cylindrical shank,
A grinding wheel base for holding the electrodeposition grinding wheel rotatably about the shank axis;
A grindstone table that supports the grindstone table movably in the axial direction of the shank;
A tool support that rotatably supports the correction tool around its axis;
A tool table that supports the tool support movably in a direction perpendicular to the axial direction of the shank;
The shank axis and the correction tool axis are arranged in a direction crossing each other,
The correction tool has a cylindrical portion formed on at least one end thereof, and an annular corner portion that forms a connection portion between the end surface and the outer peripheral surface of the cylindrical portion abuts against the abrasive layer. An electrodeposition grindstone correction device characterized by the above.