JP2010115768A - Cbn grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CBN (cubic boron nitride) grinding wheel for drastically improving grinding wheel performance by taking a crystal orientation of CBN abrasive particles into account. <P>SOLUTION: In the CBN grinding wheel 4 in which an abrasive particle layer 2 including the plurality of CBN abrasive particles 6 and a bonding agent 12 is formed around a core 8 attached to a grinding wheel spindle 42 pivoted by a wheel spindle stock 41 of a grinder 40 around an axis of revolution, the respective CBN abrasive particles 6 are single crystal leaf-form abrasive particles including a ä111} surface A which is widest of the CBN abrasive particles 6 and a ä111} surface B parallel to the ä111} surface A. In the abrasive particle layer 2, the ä111} surfaces A and the ä111} surfaces B of the respective CBN abrasive particles 6 are arranged at a right angle to an outer circumferential surface of the grinding wheel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a CBN grindstone used for grinding.

  Conventionally, when steel material is ground efficiently with a grinding wheel, a grindstone using CBN (Cubic Boron Nitride) as abrasive grains is used. In this CBN grindstone 62, as shown in FIGS. 15 and 16, the crystal plane in which the CBN abrasive grains 64 form the abrasive grains themselves on the outer periphery of the disk-shaped base metal (core) 66 is oriented in any direction. Regardless of whether they are arranged or fixed by the binder 12.

Further, according to the invention of Patent Document 1, in the octahedral crystal of diamond, the octahedron surface is exposed (from the surface of the grindstone) in parallel with the rotation direction of the contact surface, or three of which are bounded by the octahedron surface. Any one of the ridge lines is implanted in the grinding surface of the grindstone so as to be exposed (from the surface of the grindstone) in parallel with the direction of the relative rotational speed vector on the contact surface. Thus, a rotary diamond dresser with high wear resistance is provided by enabling dressing using the hardest direction of the diamond crystal plane.
JP 54-86893 A

  However, as shown in FIG. 16, many CBN abrasive grains 64 are generally close to a sphere, and when this is worn, the surface used for cutting becomes flat like a table (see FIG. 17). The contact area with the object increases and the grinding resistance increases. Such an increase in grinding resistance of the abrasive grains caused grinding burns and poor accuracy. Further, the grinding layer in the electrodeposition wheel is formed as a single layer of CBN abrasive grains, and the wear of the CBN abrasive grains directly becomes the life of the grindstone.

  Patent Document 1 discloses a rotary diamond dresser that performs dressing in consideration of the direction of hardness characteristics of the crystal face of octahedral crystal diamond. However, unlike diamond, CBN abrasive grains have single crystal grains with various crystal shapes. By considering the crystal orientation of specific crystal shapes of CBN abrasive grains, the performance of CBN grinding stones can be improved. It was very difficult to come up with a contribution.

  In order to solve the above-described problems, an object of the present invention is to provide a CBN grindstone in which the grindstone performance is remarkably improved by considering the crystal orientation of the CBN abrasive grains.

  In order to solve the above-mentioned problem, a structural feature of the invention according to claim 1 is that a plurality of CBN abrasive grains are provided around a core mounted on a grindstone shaft supported about a rotation axis on a grindstone table of a grinding machine. In the CBN grindstone in which the abrasive grain layer containing the binder and the binder is formed, each of the CBN abrasive grains is parallel to the {111} plane that is the widest plane in the CBN abrasive grain and the {111} plane. A single crystal plate-like abrasive grain having another {111} face, and the abrasive grain layer includes a {111} face and another {111} face of each CBN abrasive grain with respect to a grindstone outer peripheral face. Is oriented in a perpendicular direction.

  The structural feature of the invention according to claim 2 is that, in claim 1, the other {111} face is the second largest face in the CBN abrasive grains.

  The structural feature of the invention according to claim 3 is that, in claim 1 or 2, the core is made of metal and the binder is electrodeposition plating.

  According to the first aspect of the present invention, the {111} plane and other {111} planes of the plate-like CBN abrasive grains are oriented so as to be perpendicular to the outer peripheral surface of the grindstone. In such a case, the {111} plane which is the widest flat plate surface and the other {111} plane form both sides of the plate-like abrasive grains, whereas the surface on which the CBN abrasive grains are worn by grinding is a narrow plane. It becomes. Therefore, even if the abrasive grains are worn by continuous processing, the contact area of the abrasive grains with the workpiece does not change greatly, and the grinding resistance is not increased. Further, since the above-mentioned surface to be abraded becomes a fine uneven surface by cleaving wear, the frictional force is reduced as compared with the case where the surface is worn out smoothly and the grinding resistance can be lowered. Therefore, it is possible to maintain high performance that does not cause grinding burn or poor accuracy.

  According to the invention of claim 2, the plate-like abrasive is sandwiched between two wide {111} planes, the {111} plane which is the widest plane and the other {111} plane which is the second widest plane. Because it is plate-shaped, for example, there is less variation in rake angle compared to regular octahedral abrasive grains, etc., so there is less variation in resistance and wear during processing of individual abrasive grains, and the desired finished surface roughness can be easily obtained. .

  According to the invention according to claim 3, since the abrasive grain layer is a single layer, by providing the CBN abrasive grains on the outer periphery of the conductive core by electrodeposition, the direction perpendicular to the outer peripheral surface of the grindstone It is possible to easily provide abrasive grains.

  Hereinafter, a grinding method and a grindstone used therefor according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a CBN electrodeposited grindstone 4 as a CBN grindstone in which an abrasive layer 2 containing CBN abrasive grains is formed by electrodeposition. FIG. 2 shows an example of a grinder on which the CBN electrodeposited grindstone 4 is mounted. FIG.

  The CBN electrodeposition grindstone 4 includes a disc-shaped core 8 formed of a metal such as iron or aluminum, and a binder (nickel plating) 12 (see FIG. 7) on the outer peripheral surface of the core 8 so that the CBN abrasive grains 6 are electrically connected. It is comprised from the single-layered abrasive grain layer 2 formed by adhere | attaching.

  The CBN electrodeposited grindstone 4 is mounted with a core 8 on a grindstone shaft 42 that is rotatably supported around an axis O on a grindstone base 41 of a grinding machine 40 shown in FIG. The workpiece W is rotatably supported on the workpiece support device 43 of the grinding machine 40, and the grinding surface 45 formed on the abrasive grain layer 2 of the grindstone 4 comes into contact with the workpiece W by the advance of the grindstone table 41. The outer peripheral surface of the workpiece W is configured to be ground.

  Further, as shown in FIGS. 3 and 4, the single crystal body of the CBN abrasive grains 6 shown in FIG. 5 includes a hexagonal {111} plane A, a triangular {111} plane B, and other crystal planes. It is a plate-like abrasive grain. Here, the {111} plane A is the widest plane among the CBN abrasive grains 6, and the other {111} plane B is the second widest plane. The two {111} planes A and B, which are these broad planes, are close-packed planes in which atoms are stacked, and the CBN abrasive grains 6 have a height in the direction parallel to these {111} planes A and B. Has wear resistance. The other (100), (010), and (001) planes, which are not shown as other crystal planes, are equivalent planes that coincide with each other when rotated by 90 degrees on each axis. expressed. In the CBN electrodeposited grindstone 4, a plurality of CBN abrasive grains 6 are oriented at {111} planes A and B at right angles to the outer peripheral surface of the grindstone, and a single abrasive layer is formed on the outer periphery of the core 8. Each CBN abrasive grain 6 is configured by embedding 50 to 70% (preferably 60%) of the whole in a binder 12 formed in a layer form, as shown in FIG.

  Here, an example of a method for selecting plate-shaped abrasive grains having wide {111} planes A and B from CBN abrasive grains 6 including various shapes will be described below. First, as shown in FIG. 8, a mortar-shaped sorting container 50 having a stepped bottom that transitions downward from the outer peripheral side toward the center side is provided, and the sorting container 50 is, for example, a horizontal vibration device 52 having a slider crank mechanism. To install. Then, the CBN abrasive grains 6 to be sorted are arranged on the upper staircase 50 a on the outer peripheral side of the sorting container 50. Then, fine horizontal vibration is applied to the sorting container 50. Then, the CBN abrasive grains 6a having a relatively round shape such as abrasive grains that are easy to roll fall from the upper stage (upper stairs) 50a to the middle stage 50b and further to the lower stage 50c on the center side, and the plate-like CBN abrasive grains 6b that are difficult to roll are upper in the stairs 50a remains. Then, the plate-like CBN abrasive grains 6b remaining on the upper staircase 50a are used except for the abrasive grains 6a accumulated in the lower stage 50c.

  The selected plate-like CBN abrasive grains 6b are arranged on the outer peripheral surface of the core 8 by the following method, for example. First, as shown in FIGS. 10 and 11, each film tape 26 (see FIG. 9) having the adhesive 24 applied to the surface thereof is subjected to, for example, a multi-axis control robot (not shown) having a thin suction nozzle as shown in FIGS. The plate-like CBN abrasive grains 6b are adsorbed and arranged so as to be parallel to each other. The width of the tape 26 is substantially the same as the outer peripheral width of the core 8, and the length of the tape 26 is of a length that covers the entire outer periphery of the core 8. After the plate-like CBN abrasive grains 6b are arranged on the tape 26 to such a length as to cover the outer periphery of the core 8, as shown in FIG. Surround the outer periphery by one round. Then, the tips of the plate-like CBN abrasive grains 6b are brought into contact with the outer peripheral surface of the core 8 so that the film-like tape 26 and the core 8 are relatively positioned so that the abrasive grains 6b stand in the normal direction of the core outer peripheral surface. Secure it so that it does not move. Next, as shown in FIG. 13, nickel plating (binder 12) is performed by electrodeposition. And as shown in FIG. 14, the CBN electrodeposition grindstone 4 is formed by removing the film-like tape 26. In addition, like this manufacturing method, it is not limited to arrange | positioning the plate-like CBN abrasive grain 6b on the outer peripheral surface of the core 8 using a film-like tape, For example, it arrange | positions directly on an outer periphery of a core with a multi-axis control robot. Thus, the abrasive grains may be oriented and arranged at right angles to the outer peripheral surface of the grindstone.

  Next, the operation of the CBN electrodepositing grindstone 4 configured as described above will be described below. The CBN electrodeposition grindstone 4 is mounted on a grindstone shaft 42 supported by a grindstone base 41 of a grinding machine 40 with a core 8 and is driven to rotate. The workpiece W is transferred to a workpiece support device 43 including a headstock and a tailstock. It is supported and rotated. Grinding fluid is supplied from a coolant nozzle (not shown) attached to the grindstone cover 44 toward the contact surface between the grinding surface 45 of the CBN electrodeposited grindstone 4 and the workpiece W, so that the grindstone base 41 faces the workpiece W. The workpiece W is ground by the CBN electrodeposition grindstone 4. In grinding, the wide {111} planes A and B of the plate-like CBN abrasive grains are oriented at right angles to the outer peripheral surface of the grindstone. The contact area of the grain with the workpiece does not change significantly.

  The operation of the CBN electrodeposition grindstone 4 configured as described above will be described below. According to the CBN electrodeposition grindstone 4 of the present embodiment, the {111} planes A and B of the plate-like CBN abrasive grains are oriented so as to be perpendicular to the outer peripheral surface of the grindstone. In such a case, the {111} plane A, which is the widest flat plate surface, and the other {111} plane B parallel to the {111} plane A form both sides of the plate-shaped abrasive grains, whereas CBN is obtained by grinding. The surface on which the abrasive crystal is worn (flank) is a narrow surface. Therefore, even if the abrasive grains are worn by continuous processing, the contact area of the abrasive grains with the workpiece does not change greatly, and the grinding resistance is not increased. Further, since the above-mentioned surface to be abraded becomes a fine uneven surface by cleaving wear, the frictional force is reduced as compared with the case where the surface is worn out smoothly and the grinding resistance can be lowered. Therefore, it is possible to maintain high performance that does not cause grinding burn or poor accuracy.

  Further, the CBN abrasive grains 6b used are plate-shaped sandwiched between two wide {111} planes, the {111} plane which is the widest plane and the other {111} plane which is the second widest plane. For example, since there is less variation in the rake angle than regular octahedral abrasive grains and the like, there is little variation in resistance and wear amount during processing of each abrasive grain 6, and a desired finished surface roughness can be easily obtained.

  Further, since the abrasive grain layer 2 is a single layer, the abrasive grains 6 can be easily provided in a predetermined direction by providing the CBN abrasive grains 6 on the outer periphery of the conductive core 8 by electrodeposition. .

  In the above embodiment, the CBN abrasive grains are held by electrodeposition by nickel plating. However, the present invention is not limited to this. For example, a low melting point metal bond can be used as a binder.

  Further, the {111} plane B parallel to the widest {111} plane A is the second largest plane in the CBN abrasive grains, but is not limited to this. The {111} plane B is plate-shaped. Other than the second, for example, the third widest surface may be used as long as it forms a wide surface of the abrasive grains.

1 is an overall view of a grindstone showing a first embodiment of the present invention. The figure which shows the state which grinds a workpiece with the grinder equipped with the CBN grindstone. The figure which shows the {111} surface of the crystal body of a CBN abrasive grain. The figure which shows the {111} surface of the crystal body of a CBN abrasive grain. The figure which shows a CBN abrasive grain. The figure which shows a CBN abrasive grain. The figure which shows the state by which the CBN abrasive grain was embedded in the plating layer. The figure which shows the method of providing a plate-shaped abrasive grain in the outer periphery of a core. The figure which shows the selection method of a plate-like abrasive grain. Sectional drawing which shows a film-like tape. The figure which shows the state by which the CBN abrasive grain was provided in the film-like tape. The figure which shows the state by which the CBN abrasive grain was provided in the film-like tape. The figure which shows the manufacturing process using a film-like tape. The figure which shows the manufacturing process using a film-like tape. The figure which shows the manufacturing process using a film-like tape. The figure which shows the CBN grindstone of a prior art example. The figure which shows the CBN grindstone of a prior art example. The figure which shows the abrasion state of the CBN abrasive grain of a prior art example.

Explanation of symbols

2 ... abrasive layer, 4 ... CBN grinding wheel (CBN electrodeposition grinding stone), 6 ... CBN abrasive grain, 6b ... plate-like abrasive grain (plate-like CBN abrasive grain), 8 ... core , 12 ... Binder (Electroplating / Nickel plating), 40 ... Grinding machine, 41 ... Grinding wheel base, 42 ... Grinding wheel shaft, A ... {111} plane, B ... Other {111} faces.

Claims (3)

In a CBN grindstone in which an abrasive layer including a plurality of CBN abrasive grains and a binder is formed around a core mounted on a grindstone shaft supported around a rotation axis on a grindstone table of a grinder,
Each of the CBN abrasive grains is a single crystal plate-like abrasive grain having a {111} plane which is the widest surface in the CBN abrasive grains and another {111} plane parallel to the {111} plane. CBN, wherein the abrasive grain layer is provided with {111} planes and other {111} planes of the CBN abrasive grains oriented in a direction perpendicular to the outer peripheral surface of the grindstone. Whetstone.   2. The CBN grindstone according to claim 1, wherein the other {111} surface is the second widest surface in each of the CBN abrasive grains. 3. The CBN grindstone according to claim 1, wherein the core is made of metal and the binder is electrodeposition plating.

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