JP2011104714A - Method for suppressing initial wear of surface grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for suppressing initial wear of surface grinding wheels capable of suppressing initial wear of the surface grinding wheels and holding a width dimension of a workpiece with high accuracy. <P>SOLUTION: This method is used in a two-sided surface grinding device for simultaneously surface-grinding both surfaces of the workpiece W by a pair of rotatable surface grinding wheels 13 and 14 arranged oppositely. When a grinding wheel 31 for dressing is inserted between the pair of surface grinding wheels 13 and 14 after performing surface-grinding for the workpiece W and dressing is performed by cutting the surface grinding wheels 13 and 14 in relation to the grinding wheel 31 for dressing, the number of times of cutting of the surface grinding wheels 13 and 14 in relation to the grinding wheel for dressing is set to secure projecting amount of abrasive grains by leaving worn abrasive grains 25. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for suppressing the initial wear of a surface grinding wheel that suppresses the initial wear of the surface grinding wheel and can maintain the width dimension of the workpiece with high accuracy.

  As a double-head surface grinding apparatus that feeds a workpiece between two surface grinding wheels facing each other and simultaneously grinds both surfaces of the workpiece, a device described in Patent Document 1, for example, is known. Conventionally, in a workpiece such as a cam ring used in a vane pump, the width dimension tolerance C of the workpiece (cam ring) is finished within, for example, ± 5 μm by surface grinding.

  In such a cam ring used in the vane pump, in order to prevent the seizure of the rotor accommodated in the cam ring and the leakage of the pressure oil from the side clearance at the time of the high pressure of the vane pump, according to the width of the cam ring. Combination fitting is performed so that the side clearance of the rotor incorporated in the cam ring is maintained at a target dimension. However, in order to simplify the assembly process of the vane pump, attempts have been made to eliminate the combination fitting. In order to eliminate such combination fitting, it is necessary to finish the width dimension tolerance of the cam ring within ± 1 μm, for example.

JP 2008-229817 A

  As shown in FIG. 10, in the case where the resinoid CBN grindstone is used as the surface grindstone of the above-described double-head surface grinder, as shown in FIG. 10, the surface grindstone is first trued and immediately mounted on the double-head surface grinder. Immediately after the dressing is performed after grinding a predetermined number of objects, the wear unstable region Z1 in which the initial wear of the grindstone is large, and the wear stable region Z2 in which the grindstone wear amount proceeds at a constant rate according to the grinding amount thereafter. It becomes. For this reason, in the wear stable region Z2 in which the grinding wheel wear amount proceeds at a constant rate, by using the automatic width dimension correction function, as shown by a two-dot chain line S in FIG. Can be within a target of ± 1 μm. However, in the unstable wear zone Z1 immediately after mounting the grindstone and immediately after the dressing dress, the change in the amount of grindstone wear is unstable. Therefore, even if the width dimension correction is performed, the target width dimension tolerance C of the workpiece is obtained. There was a problem that could not be done.

  The present invention has been made in view of the above-described conventional problems, and suppresses initial wear of a surface grinding wheel, and suppresses initial wear of a surface grinding wheel capable of ensuring the tolerance of the width dimension of a workpiece with high accuracy. It is intended to provide a method.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a surface grinding wheel in a double-sided surface grinding apparatus that simultaneously grinds both surfaces of a workpiece by a pair of rotatable surface grinding wheels arranged opposite to each other. An initial wear suppression method comprising: cutting a surface of the workpiece, inserting a dressing grindstone between the pair of surface grindstones, cutting the surface grindstone into the dressing grindstone, and sharpening the dress In this case, the number of cuts of the surface grinding wheel with respect to the dressing grindstone is set so as to leave the worn abrasive grains and ensure the protruding amount of the abrasive grains.

  A feature of the invention according to claim 2 is that, in claim 1, dressing is carried out so as to leave worn abrasive grains while ensuring a protruding amount of the abrasive grains of 12 to 15 μm.

  According to a third aspect of the present invention, in the first or second aspect, when the surface grinding wheel is mounted on the double-sided surface grinding device and the surface grinding wheel is trued, The truing is performed by relatively moving the outer peripheral surface of a diamond truer having a predetermined width rotatable around an axis parallel to the grinding surface of the grindstone in the radial direction of the surface grinding grindstone with a small cutting amount of 5 μm or less.

  A feature of the invention according to claim 4 is that, in any one of claims 1 to 3, the surface grinding wheel is composed of a resinoid CBN wheel.

  According to the invention according to claim 1, the feature of the invention according to claim 1 is that surface grinding in a double-head surface grinding apparatus that simultaneously grinds both surfaces of a workpiece with a pair of rotatable surface grinding wheels arranged opposite to each other. A method for suppressing the initial wear of a grindstone, when a workpiece is surface ground and then a dressing grindstone is inserted between a pair of surface grindstones and the surface grindstone is cut into the dress grindstone and dressed sharply Since the number of cuts of the surface grinding wheel with respect to the dressing wheel is set so as to keep the abrasive grains protruding while leaving the worn abrasive grains, the worn abrasive grains fall off while ensuring the abrasive protrusion. It can remain without causing it. Thereby, initial wear immediately after carrying out the dressing can be suppressed, and the width dimension tolerance of the workpiece can be maintained within the target intersection by the automatic width dimension correcting function.

  According to the second aspect of the present invention, the dressing interval is not shortened because the dressing is performed so as to leave the worn abrasive grains while securing the protruding amount of the abrasive grains of 12 to 15 μm.

  According to the third aspect of the present invention, when the surface grinding wheel is trued by attaching the surface grinding wheel to the double-sided surface grinding device, the surface grinding wheel can be rotated around an axis parallel to the grinding surface of the surface grinding wheel. Because the truing is performed by moving the outer peripheral surface of the diamond truer with a predetermined width relative to the radial direction of the surface grinding wheel with a small incision amount of 5 μm or less, the crushed abrasive grains are reduced, and the unevenness at the tip of the abrasive grains is reduced. Can be formed into a flat state. Thereby, in addition to the effect of the invention according to claim 1, it is possible to suppress the initial wear immediately after mounting the grindstone even immediately after mounting the grindstone mounted on the double-sided surface grinding apparatus, and the automatic width dimension correcting function. The workpiece width dimension tolerance can be maintained within the target intersection.

  According to the invention which concerns on Claim 4, since the surface grinding grindstone is comprised from the resinoid CBN grindstone, control of the protrusion amount of an abrasive grain can be easily performed with a dressing dress.

It is sectional drawing of the surface grinding wheel part of the double-head surface grinding apparatus which shows embodiment of this invention. FIG. 2 is a view taken along the line 2-2 in FIG. It is a figure which shows the state which truing a surface grinding grindstone. It is a figure which shows the unevenness | corrugation of the abrasive grain of a surface grinding grindstone. It is a comparison figure which shows the change of the grindstone wear amount with respect to the grinding number after a grindstone attachment. It is a figure which shows the state which dresses a surface grindstone sharply. It is the figure seen from the arrow along the 7-7 line of FIG. It is a comparison figure which shows the change of the grindstone wear amount with respect to the grinding number after dressing dress. It is a figure which shows the change of the abrasive grain protrusion amount with respect to the frequency | count of dress cutting. It is a figure which shows the change of the wear amount of the grindstone with respect to the grinding amount in the past, and the width dimension of a workpiece. It is a figure which shows the state which truing the conventional surface grinding grindstone.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a method for suppressing initial wear of a surface grinding wheel according to the present invention will be described with reference to the drawings. 1 and 2, the vertical double-head surface grinding apparatus includes a pair of surface grinding wheels 13 and 14 that are opposed to each other in the vertical direction and rotate about the coaxial grinding wheel shafts 11 and 12.

  Further, as is well known, the vertical double-head surface grinding apparatus has a swingable carrier 15 in which a pocket hole 16 for holding a cylindrical workpiece W rotatably is formed. The thickness of the carrier 15 is made thinner than the width of the workpiece W, and the workpiece W is fed between the pair of surface grinding wheels 13 and 14 by the swing of the carrier 15, and both surfaces of the workpiece W are surface ground. Surface grinding is performed simultaneously by the grinding wheels grinding surfaces 13a and 14a of the grinding wheels 13 and 14.

  The workpiece W is, for example, a cam ring having a predetermined width used for a vane pump, and the outer periphery thereof is formed in a perfect circle shape, and has a cam-shaped inner peripheral surface that houses the rotor in the center.

  The pair of surface grinding wheels 13, 14 includes cup-shaped metal substrates 17, 18 whose inner and outer circumferences are concentrically fixed to the lower and upper ends of coaxial grinding wheel shafts 11, 12 that can rotate around a vertical axis. I have. Ring-shaped grindstone layers 19 and 20 having a predetermined thickness are formed on the upper and lower surfaces of the metal substrates 17 and 18, and grindstone grinding surfaces 13 a and 14 a parallel to each other are formed on the respective tip surfaces of the grindstone layers 19 and 20. Has been. The grindstone layers 19 and 20 are made of a resinoid CBN grindstone in which a large number of CBN abrasive grains are bonded with resinoid bonds.

  Each of the grindstone shafts 11 and 12 is rotationally driven by a grindstone shaft driving means (not shown) and is advanced and retracted in the vertical direction by a grindstone shaft feeding means (not shown). Further, at least one of the grindstone shafts 11 and 12 can be vertically cut by a grindstone shaft cutting means (not shown).

  FIG. 3 shows a state in which the grinding surfaces 13a and 14a of the surface grinding wheels 13 and 14 are trued before the surface grinding wheels 13 and 14 are attached to the grinding wheel shafts 11 and 12, respectively.

  Such truing is performed using a diamond truer. Conventionally, as shown in FIG. 11, a surface grinding wheel 13 (14) is mounted on a truing arbor 3 rotatably supported by both centers 1 and 2. Further, as the diamond truer 5, a diamond truer 5 having a thin diamond truer portion 7 in which diamond grains are bonded to the outer periphery of a disk-shaped metal substrate 6 by a metal bond or the like is used. Then, as shown in FIG. 11, the diamond truer 5 is tilted by a predetermined angle with respect to the grindstone grinding surface 13a (14a) of the surface grinding grindstone 13 (14), and the diamond truer 5 is grinded with the grindstone grinding surface 13a (14a). The diamond truer 5 is cut in the X direction with a large cutting amount (for example, 15 μm), and the diamond truer 5 is relatively reciprocated in the radial direction (Y direction) along the grinding wheel grinding surface 13a (14a). The grindstone grinding surface 13a (14a) is trued by the edge portion of the truer 5.

  Thus, conventionally, since the cutting amount of the diamond truer 5 is large, the edge grinding surface 13a (14a) of the surface grinding stone 13 (14) is trued by the edge portion of the diamond truer 5. As shown in FIG. 4A, the abrasive grains 25 of the surface grinding grindstone 13 (14) are easily crushed, and the claw level difference L1 at the tip of the abrasive grains 25 is increased to about 1.5 μm by the crushing. Therefore, immediately after mounting the grinding wheel 13 (14) thus trued to the double-headed surface grinding apparatus and grinding the workpiece W, the irregularities at the tip of the abrasive grains 25 are large, and therefore, FIG. As shown in (A), the initial wear (abrasion wheel wear amount) of the abrasive grains 25 is large and the initial wear is not stable until the surface of about 200 workpieces W is ground, and the width dimension tolerance of the work W is not stable. C cannot be secured within a predetermined target intersection (for example, ± 1 μm).

  When about 200 workpieces W are ground, as shown in FIG. 4B, the sharp tip of the abrasive grain 25 is worn and flattened, and the uneven step L2 at the tip of the abrasive grain 25 is zero. After that, the abrasive grains 25 are gradually worn in proportion to the number of ground workpieces W.

  Therefore, in the present embodiment, the surface grinding wheel 13 (14) is set so that the grinding wheel wear amount immediately after mounting the grinding wheel is set to a constant wear stable region Z2, and the target width dimension tolerance can be secured by automatic width dimension correction. The truing was changed as follows.

  That is, as shown in FIG. 3, the grinding wheel grinding surface 13 a (14 a) is directed upward to the mounting jig 22 installed on the upper surface of the rotary table 21 that can rotate about the vertical axis. And install. The attachment jig 22 has the same attachment reference surface as the double-head surface grinding apparatus. Further, the rotatable diamond truer 23 for truing the grindstone grinding surface 13a (14a) of the surface grinding grindstone 13 (14) has diamond abrasive grains 25 bonded to the outer periphery of a disk-shaped metal substrate 24 by a metal bond or the like. A ring-shaped diamond truer portion 26 having a wide width (for example, 10 mm) was fitted, and the diamond truer 23 was arranged so that the rotation center thereof was parallel to the grinding wheel grinding surface 13a (14a). In this state, the diamond truer 23 and the rotary table 21 are rotated, and the diamond truer 23 is cut in the axial direction (X direction) of the surface grinding wheel 13 (14) with a small cutting amount of 5 μm or less, preferably about 2 μm. At the same time, the grinding wheel grinding surface 13a (14a) is trued by the outer peripheral surface 26a of the wide diamond truer portion 26 by reciprocating in the radial direction (Y direction) of the grinding wheel grinding surface 13a (14a).

  As described above, by reducing the cutting amount of the diamond truer 23 and using the outer peripheral surface 26a of the wide diamond truer portion 26 to true the grindstone grinding surface 13a (14a), the surface grinding grindstones 13 and 14 are removed. Immediately after mounting the grindstone mounted on the double-sided surface grinder, the crushing abrasive grains of the grindstone 25 on the grindstone grinding surface 13a (14a) are reduced, and the uneven step at the tip of the abrasive grain 25 has a flatness of 0.5 μm or less. It became possible to be molded into a proper state. That is, even immediately after mounting the grindstone, a flattened abrasive grain 25 as shown in FIG. 4 (B) can be realized. As shown in FIG. A grindstone surface state that becomes the wear stable region Z2 can be created.

  As a result, as shown in FIG. 5A, initial wear immediately after the surface grinding wheels 13 and 14 are attached to the grindstone shafts 11 and 12 can be reduced, and the amount of wear of the grindstone is proportional to the number of grinding wheels. Thus, the automatic width dimension correcting function can make the width dimension tolerance of the workpiece W within a target tolerance (for example, 1 μm).

  6 and 7 show a state in which the grindstone grinding surfaces 13a and 14a of the surface grinding wheels 13 and 14 are dressed conspicuously every time a predetermined number of workpieces W (for example, 1500) are ground. Indicates a rotatable dressing disc on which a plurality of stick grindstones 31 as dressing grindstones are attached at equal angular intervals on the circumference. The stick grindstone 31 is a WA (white alundum) grindstone.

  In the dressing dress, with the dressing disc 30 rotated, as shown in FIG. 6, a stick grindstone 41 is inserted between the rotating surface grindstones 13 and 14, and the grindstone shafts 15 and 16 are attached to the stick. The surface grinding wheels 13 and 14 are dressed conspicuously while cutting the grinding wheel 31 by a minute amount. That is, the resinoid bond holding the abrasive grain 25 is scraped off by the stick grindstone 31 so that the abrasive grain 25 protrudes by a necessary amount.

  By the way, in this type of dressing dress, a fine cut (for example, 3 μm) is conventionally used to scrape off the resinoid bond so that the abrasive grains 25 worn away by grinding are dropped and the sharp abrasive grains 25 are projected. Is repeated about 200 times to perform a dressing for making the abrasive grains 25 protrude 15 μm or more. However, by performing such a dress cycle, the worn abrasive grains 25 fall off and new sharp abrasive grains 25 with large irregularities are protruded. Therefore, immediately after the dressing is performed, FIG. As shown in (2), until about 200 workpieces W are ground, the initial wear of the abrasive grains 25 is large and the initial wear is not stable, and the width tolerance of the workpiece W is set to the target intersection (± 1 μm). The current situation is that it cannot be kept within.

  Therefore, in the present embodiment, in order to allow the workpiece W to be finished within the target width dimension tolerance by making the grinding wheel wear amount after the dressing dress constant and performing automatic width dimension correction, By making the fine cutting frequency of the surface grinding wheels 13 and 14 about 50 times that of the conventional 1/4, the abrasive grains 25 remain without dropping while securing the protruding amount of the abrasive grains 25. It has succeeded in making it happen. In this case, according to the experimental results, the protrusion amount of the abrasive grains 25 is slightly smaller than the protrusion amount when the cutting number is 200 as shown in FIG. 12 to 15 μm), however, this protrusion amount is an amount that does not hinder surface grinding of the workpiece W, and the dress interval is not shortened.

  In this way, by reducing the number of cuttings of the dressing dress to about 1/4 (50 times) of the conventional dressing, it is possible to produce the workpiece without grinding about 200 workpieces W after the conventional dressing dressing is performed. The grindstone surface condition that did not exist can be realized immediately after the dressing.

  Therefore, according to the present embodiment, as shown in FIG. 8 (B), the grindstone surface state in which the grindstone wear becomes a constant wear stable region Z2 can be created immediately after the dressing is performed. With the width dimension correcting function, the width dimension tolerance of the workpiece W can be within the target intersection (± 1 μm), and it is possible to eliminate the complicated combination fitting in the cam ring of the conventional vane pump.

  In addition, the cutting frequency of the dressing dress described in the embodiment is about 50 times, which is a value obtained as a result of an experiment using an existing vertical double-sided surface grinding apparatus, and the present invention is not necessarily limited to 50 times. As a guideline, the above-described results can be obtained by reducing the number of cuts to about 1/4 of the conventional number of cuts. The point is that the number of times of cutting can leave the worn abrasive grains 25 while securing the protruding amount of the abrasive grains 25.

  In the above-described embodiment, an example in which a CBN grindstone in which CBN abrasive grains are bonded by a resinoid bond is used as the surface grindstones 13 and 14 of the double-sided surface grinder has been described. Although effective in terms of easy control of the amount, the present invention is not particularly limited to resinoid bonds or CBN abrasive grains.

  It should be noted that the present invention is effective by performing only the dressing dress performed for each predetermined number of grindings as described in the above embodiment.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited to the configurations described in the embodiments, and can take various forms within the scope described in the claims. Is.

  The method for suppressing the initial wear of a surface grinding wheel according to the present invention is suitable for use in a double-head surface grinding apparatus that performs surface grinding on both surfaces in the width direction of a workpiece with a resinoid CBN wheel.

DESCRIPTION OF SYMBOLS 11, 12 ... Grinding wheel axis | shaft, 13, 14 ... Surface grinding grindstone, 13a, 14a ... Grinding wheel grinding surface, 23 ... Diamond truer, 25 ... Abrasive grain, 31 ... Dressing grindstone (stick grindstone), W ... Workpiece.

Claims (4)

A method for suppressing initial wear of a surface grinding wheel in a double-sided surface grinding apparatus for simultaneously grounding both surfaces of a workpiece by a pair of rotatable surface grinding wheels arranged oppositely,
After the surface of the workpiece is ground, a dressing grindstone is inserted between the pair of surface grindstones. A method for suppressing the initial wear of a surface grinding wheel, wherein the number of cuts of the surface grinding wheel with respect to the dressing wheel is set so as to ensure a protruding amount of the abrasive grains.   2. The method for suppressing the initial wear of a surface grinding wheel according to claim 1, wherein dressing is performed so as to leave worn abrasive grains while ensuring a protruding amount of the abrasive grains of 12 to 15 [mu] m.   3. When the surface grinding wheel is trued when the surface grinding wheel is attached to the double-sided surface grinding device, the surface grinding wheel is mounted around the axis parallel to the grinding surface of the surface grinding wheel. A method for suppressing initial wear of a surface grinding wheel, characterized in that truing is carried out by relatively moving the outer peripheral surface of a rotatable diamond truer with a small cutting amount of 5 μm or less in the radial direction of the surface grinding wheel. 4. The method for suppressing the initial wear of a surface grinding wheel according to claim 1, wherein the surface grinding wheel is composed of a resinoid CBN wheel.

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