JP2008142796A - Compound whetstone - Google Patents

Abstract

An object of the present invention is to easily prevent cracking or chipping of an abrasive layer by filling a recess opening in the grinding surface of an abrasive layer with a brittle material and improving the function of discharging grinding scraps. A composite grindstone is provided.
A plurality of grindstone chips having an abrasive grain layer 12 containing superabrasive grains are affixed to a core mounted on a grindstone shaft that is rotatably supported about an axis on a grindstone table of a grinder. In a grindstone 10 in which a grinding surface 15 formed on a grain layer contacts and grinds a workpiece supported by a workpiece support device of the grinding machine so as to be rotationally driven at a grinding point. A plurality of recesses 20 are formed in the grinding surface, and the recesses are filled with a brittle material 50 having a high porosity or a vitrified grinding stone material having a high porosity.
[Selection] Figure 4

Description

  The present invention relates to a composite grindstone in which a grinding surface of an abrasive grain layer is filled with a brittle material including a hollow sphere and a porous material.

An abrasive layer containing superabrasive grains such as diamond or cubic boron nitride is formed on the outer peripheral surface of a disk-shaped core that is driven to rotate about the rotation axis, and a predetermined width is provided on the outer peripheral surface of the abrasive layer. Patent Document 1 discloses a grooved grindstone in which an inclined groove having a depth is engraved with an inclination of about 25 to 45 degrees with respect to the axis of the core. According to such a grooved grindstone, the grinding liquid can be effectively introduced to the grinding point along the inclined groove, and the removal amount by grinding is about 1.5 times that of the grindstone without the inclined groove. Increase the grinding efficiency.
JP 2000-354969 (paragraphs [0007], [0026], FIG. 1)

  However, according to the above-mentioned grooved grindstone, the inclined grooves are engraved to both end surfaces of the abrasive layer perpendicular to the rotation axis, and each end surface and the side wall surface of the inclined groove form an acute angle. There is a problem that the strength of is insufficient at the acute angle portion, and cracking or chipping of the abrasive layer is likely to occur due to grinding resistance. In addition, the grindstone is required to have an improved grinding waste discharging function as one of basic functions.

  The present invention has been made in view of the conventional problems, and it is easy to cause cracks and chipping of the abrasive layer by filling a concave portion opened in the grinding surface of the abrasive layer with a brittle material. Therefore, it is possible to provide a composite grindstone that can be prevented and improve the function of discharging grinding scraps.

  In order to solve the above-described problem, the structural feature of the invention according to claim 1 is that a superabrasive grain is attached to a core that is mounted on a grindstone shaft that is rotatably supported on a grindstone table of a grinder so as to be rotatable about an axis. A plurality of grindstone chips having an abrasive layer including affixed, and a grinding surface formed on the abrasive layer abuts a workpiece supported rotatably on the workpiece support device of the grinder at a grinding point. In the grindstone for grinding, the abrasive layer is formed with a plurality of recesses opened in the grinding surface, and the recesses are filled with a brittle material having a high porosity or a vitrified grindstone material having a high porosity. That is.

  The structural feature of the invention according to claim 2 is that, in claim 1, the recess is a plurality of inclined grooves inclined in the circumferential direction of the grindstone.

  The structural feature of the invention according to claim 3 is that, in claim 1, the recesses are a plurality of hole-like recesses scattered on the grinding surface.

  According to the first aspect of the present invention, in the grindstone in which a plurality of grindstone chips having an abrasive layer containing superabrasive grains are stuck to the core, the porosity of the brittle material having a high porosity filled in the recesses opened in the grinding surface Are continuously destroyed by grinding, and a large number of destroyed pores form grinding waste discharge pockets, so that grinding waste can be effectively discharged to enable highly efficient grinding.

  In addition, the dynamic pressure of the grinding fluid supplied to the grinding point can be released by the collection of fine spaces generated by the broken pores. In addition, even when a portion where stress tends to concentrate on the abrasive layer is formed by forming the recess, it is reinforced by filling the recess with a brittle material to prevent the stress from concentrating, so that the abrasive layer is ground. It is possible to prevent cracking or chipping due to resistance.

  Also, when the recess is filled with vitrified grinding stone material with high porosity (made of abrasive grains bonded by vitrified bond), the scrap formed by the vitrified bond can also be used as grinding dust discharge pocket. Efficiently drains and enables highly efficient grinding. Similarly, the dynamic pressure of the grinding fluid supplied to the grinding point can be released by the high porosity pores formed by the vitrified bond. Moreover, it is reinforced by filling a recessed part with a vitrified grinding stone material, and it can prevent that an abrasive grain layer produces a crack and a chip | tip by grinding resistance.

  According to the second aspect of the present invention, at the grinding point through which the inclined groove passes, the dynamic pressure of the grinding fluid supplied to the grinding point is high brittle material with high porosity or high porosity filled in the inclined groove. It is released by the vitrified grindstone material, and the workpiece is not displaced in the direction away from the grindstone to increase the work size, thereby improving the grinding accuracy, particularly the roundness.

  In addition, even if the end face of the abrasive grain layer parallel to the circumferential direction of the grinding wheel and the side wall surface of the inclined groove form an acute angle, it is reinforced by the brittle material or vitrified abrasive material filled in the inclined groove. It is possible to prevent the strength from being insufficient at the acute angle portion in the circumferential direction of the grindstone, and to prevent the abrasive grain layer from being cracked or chipped at the acute angle portion.

  According to the third aspect of the invention, the pores of the brittle material filled in the plurality of hole-shaped recesses scattered on the grinding surface are broken by grinding, and the broken pores form the discharge pockets for the grinding waste. The waste pockets temporarily hold the grinding waste and discharge it with higher efficiency than the grinding point. Also, when high porosity vitrified grinding stone material is filled in a plurality of hole-shaped recesses scattered on the grinding surface, the waste pockets are formed by vitrified bond pores. Can be discharged.

  An embodiment of a composite grindstone according to the present invention will be described below based on the drawings. FIG. 1 shows a grindstone including a segment type grindstone tip, and FIG. 2 shows a grinder on which the grindstone is mounted.

  In the grindstone tip 11 of the grindstone 10, an abrasive layer 12 in which superabrasive grains are bonded by vitrified bonds is formed on the outer peripheral side, and an underlayer 13 not including the superabrasive layer is laminated on the inside of the abrasive grain layer 12 to be integrated. Is formed. In the grindstone 10, a plurality of arc-shaped grindstone chips 11 each comprising an abrasive layer 12 and an underlayer 13 are arranged on the outer peripheral surface of a disk-shaped core 14 formed of a metal such as iron or aluminum, a resin, or a general grindstone. The base layer 13 is attached to the core 14 with an adhesive on the bottom surface. The grindstone 10 is attached by a core 14 to a grindstone shaft 32 that is supported on a grindstone base 31 of a grinder 30 shown in FIG. A workpiece W is rotatably supported on the workpiece support device 33 of the grinding machine 30, and the grinding surface 15 formed on the abrasive layer 12 of the grindstone 10 by the advance of the grindstone table 31 is applied to the workpiece W at a grinding point P. The outer peripheral surface of the workpiece W is ground by abutting with the above.

  FIG. 3 shows an arc-shaped grindstone tip 11, and the abrasive grain layer 12 is formed by bonding superabrasive grains 16 such as CBN and diamond to a thickness of 3 to 5 mm with vitrified bonds 17. For adjustment, particles such as aluminum oxide (Al2O3) may be mixed as an aggregate instead of superabrasive grains. The underlayer 13 is formed by bonding the underlayer particles 19 with a vitrified bond 17 to a thickness of 1 to 3 mm. When vitrified bond 17 is employed, the chip characteristics are excellent due to the characteristics of the pores, and the sharpness becomes good, so that the grinding wheel can be ground to a good surface roughness by reducing the wear amount of the grindstone. However, as the binder, in addition to the vitrified bond 17, a resin bond or a metal bond can be used. Further, an inclined groove 20 as a concave portion described later is formed at a depth h from the surface of the abrasive grain layer 12.

  As shown in FIG. 4, the grinding surface 15 of the grindstone 10 has a plurality of inclined grooves 20 as recesses having a width b that is inclined with respect to the circumferential direction of the grindstone, and at least one slant regardless of the rotational phase of the grindstone 10. The groove 20 is engraved so as to pass up and down the grinding point P. The inclined groove 20 reaches the end faces 21 and 22 of the abrasive grain layer parallel to the circumferential direction of the grindstone, and the end face 21 and the side wall face 23 of the inclined groove 20 and the end face 22 and the side wall face 24 of the inclined groove 20 form an acute angle. is doing. The inclined groove 20 is filled with a brittle material body 50 in which porous particles such as a shirasu balloon (brittle material) are bonded by vitrified bonds.

  In addition, as shown in FIG. 4, the inclined groove 20 filled with the brittle material body 50 always passes through the grinding point P, so that the inclined groove 20 is filled with the brittle material body 50 as described above. The brittle material (shirasu balloon) is porous, and small balloon-like (porous) shirasu balloons are continuously broken down to form voids one after another, so that the grinding fluid supplied to the grinding point P The generated dynamic pressure is released. Then, the workpiece W is not displaced in the direction away from the grindstone 10 to increase the work size, and the grinding accuracy, particularly roundness, is improved.

  Here, it is possible to effectively prevent generation of dynamic pressure in the grinding fluid supplied to the grinding point P, and to incline filled with a brittle material body 50 that can ensure high grinding accuracy and a long grinding wheel life. Conditions for creating the groove 20 are as described below from experiments and the like. The inclined groove 20 (filled with the brittle material body 50; hereinafter the same in this paragraph) has at least one, preferably two or more grinding points P within the axial length of the grinding point P regardless of the rotational phase of the grindstone 10. Is passed up and down. The groove circumferential width c, which is the width of the inclined groove 20 in the circumferential direction of the grindstone, is preferably shorter because the interval between the superabrasive grains 16 exposed on the grinding surface 15 is increased by the groove circumferential width c. In order to reduce the number of manufacturing steps, it is better that the number of grooves is small. The pitch of the inclined grooves 20 in the circumferential direction of the grindstone is preferably longer because the pitch between the inclined grooves 20 is difficult to manufacture and the strength of the grindstone tip 11 is reduced. It is better not to make the total area of the inclined grooves 20 too large since increasing the size will reduce the number of superabrasive grains 16 involved in grinding and increase the amount of grinding wheel wear.

  In consideration of these conditions, for example, a method for determining the number n of the inclined grooves 20 and the inclination angle α, which are suitable when the workpiece W having a width of 15 mm is plunge cut ground with the grindstone 10 having an outer diameter of 350 mm, will be described below. . The inclination angle α is an angle formed between the inclined groove 20 and the end surface 21 of the abrasive layer 12, that is, the circumferential direction of the grindstone, and the length in the axial direction of the grinding point P is 15 mm, which is the same as the width of the workpiece W.

  The width b in the groove normal direction of the inclined groove 20 is about 1 mm in order to reduce the groove circumferential width c, which is the length of the inclined groove 20 in the circumferential direction of the grindstone in consideration of the strength of the grindstone for grinding. It is good to do. When the inclination angle α of the groove circumferential width c and the inclined groove 20 is increased to about 15 degrees, the groove circumferential width c is reduced, and the spread of the interval between the superabrasive grains 16 by the inclined groove 20 can be suppressed.

  Thus, in the present embodiment, when the workpiece W having a width of 15 mm is plunge cut with the grindstone 10 having an outer diameter of 350 mm, the width of the workpiece W, that is, the axis of the grinding point P, regardless of the rotational phase of the grindstone 10. An example of the specifications of the inclined groove 20 (filled with brittle material) determined so that the two inclined grooves 20 pass up and down the grinding point P within the length of the direction is as follows. The depth h is 7 mm, the inclination angle α is 15 degrees, and the number n is 39.

  Next, a method of manufacturing a grindstone with an inclined groove will be described with reference to FIG. As shown in FIG. 5A, an arc-shaped concave surface 42 a corresponding to the arc surface of the grindstone chip 11 having the outer diameter of the grindstone 10 is fitted to the inner bottom portion of the rectangular outer mold 41. Is formed on the upper surface of the lower mold 42. The lower mold 42 is filled with abrasive layer powder 44 in which the superabrasive grains 16 and the vitrified bonds 17 constituting the abrasive layer 12 are mixed, and a portion to be the inclined groove 20 is formed by a partition (not shown). It is formed as a groove-shaped recess, and the recess is filled with a brittle material body 50 in which a shirasu balloon and vitrified bond are mixed. Then, the abrasive layer powder 44 and the brittle material body 50 are leveled so as to be uniform. In this state, as shown in FIG. 5B, the pressing die as the first upper die 45 is lowered along the inner surface of the outer die 41 to temporarily press the abrasive layer powder 44 and the brittle material body 50. The abrasive grain layer 12 and the brittle material layer 52 are temporarily formed into an arc shape.

  Subsequently, as shown in FIG. 5C, the ground layer powder 46 including the ground particles 19 is filled above the temporarily press-molded abrasive grain layer 12 and the brittle material layer 52, and the ground layer powder. The body 46 is leveled so that the thickness is uniform. In this state, as shown in FIG. 5 (d), the second upper mold 47 is lowered along the inner surface of the outer mold 41, and the ground layer powder 46, the abrasive grain layer 12, and the brittle material layer 52 are simultaneously placed. Press. As a result, the base layer 13 is press-molded integrally with the abrasive grain layer 12 and the brittle material layer 52 inside, and the arc-shaped grindstone chip 11 is formed. Thereafter, the second upper mold 47 is raised, and the grindstone chip 11 is released from the outer mold 41 and the lower mold 42.

  Next, the operation of the inclined grooved grindstone 10 of this embodiment will be described. The grindstone 10 is mounted on the grindstone base 32 supported by the grindstone base 31 of the grinding machine 30 shown in FIG. 2 by the core 14 and is driven to rotate, and the workpiece W is transferred to the work support device 33 including the headstock and the tailstock. It is supported and rotated. The coolant is supplied from the coolant nozzle 35 attached to the grindstone cover 34 to the grinding point P between the grindstone 10 and the workpiece W, and the grindstone base 31 is ground and fed toward the workpiece W. Is ground.

  In this case, in the grindstone 10 in which a plurality of grindstone chips 11 having an abrasive grain layer 12 containing superabrasive grains are affixed to the core, a high-porosity brittle material body (filled in the inclined grooves 20 opened in the grinding surface 15 ( The pores of the shirasu balloon (50) are continuously destroyed by grinding, and a large number of destroyed pores form grinding waste discharge pockets, so that the grinding waste can be effectively discharged to enable high-efficiency grinding. Further, the dynamic pressure of the grinding fluid supplied to the grinding point P can be released by the collection of fine spaces generated by the broken pores. Further, by forming the inclined groove 20, a point where stress is easily concentrated on the abrasive grain layer 12 (for example, the angle formed between the end faces 21 and 22 orthogonal to the circumferential direction of the grindstone and the side wall surfaces 23 and 24 of the inclined groove 20 is an acute angle). Even when a portion where the abrasive grain layer 12 becomes thin) occurs, the stress concentration is prevented by filling the inclined groove 20 with the brittle material body 50, so that the abrasive grain layer 12 is cracked by the grinding resistance. Or chipping can be prevented.

  Although at least one inclined groove passes above and below the grinding point, the present invention is not limited to this, and there may be a portion where the inclined groove does not pass in a part of the grinding surface of the grindstone.

  Next, 2nd Embodiment of the composite grindstone concerning this invention is described below based on drawing.

  In the present embodiment, as shown in FIG. 6, a hole-like hole-like recess 55 having an open surface is formed as a recess opening on the surface of the abrasive grain layer, and a brittle material body is formed in the hole-like recess 55. 50 is filled. And the hole-shaped recessed part 55 with which this brittle material body 50 was filled is arrange | positioned so that it may be scattered on the grinding surface 65 of the grindstone 60. FIG. Since other configurations are the same as those of the first embodiment, the description thereof is omitted.

  According to the composite grindstone of this embodiment, in the process in which the brittle material body 50 is scraped from the surface by grinding, a large number of fine holes are generated by the shirasu balloon, and grinding scraps are retained and discharged efficiently in the fine holes. Efficiency can be improved.

  In this embodiment, the shirasu balloon is used as the brittle material, but the present invention is not limited to this, and known hollow spheres and porous materials can be appropriately selected and used.

  In the above embodiment, a brittle material body such as a shirasu balloon is used as a material filled in the recess. However, the present invention is not limited to this. For example, a vitrified bond is used as a binder, and CBN (cubic boron nitride) or Vitrified whetstone materials using diamond as abrasive grains may be used.

The whole figure of the grindstone which consists of a segment type grindstone tip which shows an embodiment of the invention. The figure which shows the state which grinds a workpiece with the grinder equipped with the grindstone with an inclined groove. The figure which shows a grindstone chip. The figure which shows the state which engraved the some inclined groove | channel on the grinding surface of the grindstone so that at least 1 inclined groove | channel might pass a grinding point up and down. The figure which shows the manufacturing process of a grindstone chip. The figure which shows the composite grindstone of other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Whetstone, 11 ... Whetstone tip, 12 ... Abrasive grain layer, 14 ... Core, 15 ... Grinding surface, 16 ... Superabrasive grain, 20 ... Inclined groove, 31 ... Whetstone base, 50 ... Brittle material (brittle material body), 55 ... hole-shaped recess, 60 ... grinding stone, 61 ... grinding stone tip, 65 ... grinding surface, P ... grinding point, W ... workpiece.

Claims (3)

A plurality of grindstone chips having an abrasive layer containing superabrasive grains are affixed to a core that is mounted on a grindstone shaft that is rotatably supported around an axis on a grinding wheel head of a grinding machine, and formed on the abrasive grain layer. In a grindstone that grinds a workpiece with a ground surface abutting at a grinding point on a workpiece supported so as to be rotationally driven by the workpiece support device of the grinding machine,
The abrasive grain layer is formed with a plurality of recesses that open to the grinding surface, and the recesses are filled with a brittle material having a high porosity or a vitrified grinding stone material having a high porosity. .   2. The composite grindstone according to claim 1, wherein the concave portions are a plurality of inclined grooves inclined in the circumferential direction of the grindstone. The composite grindstone according to claim 1, wherein the concave portions are a plurality of hole-shaped concave portions scattered on the grinding surface.

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