JP2016087719A - Grinding wheel and manufacturing method of grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding wheel and a manufacturing method of the grinding wheel, capable of grinding a workpiece having a grinding object part of a different shape with excellent finish accuracy, by providing a plurality of kinds of grindstone layers of different properties in the axial direction.SOLUTION: A grinding wheel 10 comprises a disc-like member 13 and a grindstone layer 16 arranged on an outer peripheral surface of the disc-like member, and the grindstone layer comprises a plurality of circumferential directional divided grindstone chips divided in a circumferential direction, and the plurality of respective circumferential directional divided grindstone chips are formed by arranging a first grindstone chip 11 and a second grindstone chip 12 of different properties in an axial direction, and in the plurality of respective circumferential directional divided grindstone chips, a boundary part between the first grindstone chip and the second grindstone chip is defined as an axial directional boundary part, and among the plurality of circumferential directional divided grindstone chips, the axial directional boundary part in at least three circumferential directional divided grindstone chips continuously arranged in the circumferential direction, is aligned toward a predetermined direction in the axial direction in order of at least the three circumferential directional divided grindstone chips continuously arranged in the circumferential direction.SELECTED DRAWING: Figure 3

Description

本発明は、砥石車及び砥石車の製造方法に関する。   The present invention relates to a grinding wheel and a method for manufacturing a grinding wheel.

従来、例えば、自動車用クランクシャフトのジャーナルやクランクピン等を研削加工する研削砥石がある（下記特許文献１参照）。特許文献１に開示される研削砥石には、砥石車を形成する円板状部材の外周面に、異なる性状を有する２種類の砥石層がチップ状に分割されて設けられている。詳細には、円板状部材の外周面の回転軸方向両端角部は、研削時に大きな研削抵抗が生じるため、粒径が大きな砥粒によって形成された摩耗しにくい砥石層が設けられている。また、外周面の両端角部の間の円筒部には、大きな研削抵抗が生じないので、高い仕上げ精度が望める、粒径が小さく摩耗しやすい砥粒によって形成された砥石層が設けられている。しかし、上記においては、摩耗しにくい砥石層と摩耗しやすい砥石層とが軸方向で隣り合い、同時に研削作業を行なうので、両砥石層の摩耗の度合いが異なり、境界部に段差が発生してしまう。このため、工作物にこの段差が転写され、仕上げ精度が悪化する虞がある。   Conventionally, for example, there is a grinding wheel for grinding a journal, a crankpin, and the like of a crankshaft for an automobile (see Patent Document 1 below). In the grinding wheel disclosed in Patent Document 1, two types of grinding stone layers having different properties are provided in a chip shape on the outer peripheral surface of a disk-shaped member forming a grinding wheel. More specifically, the corners at both ends in the rotation axis direction of the outer peripheral surface of the disk-shaped member are provided with a grinding wheel layer that is formed from abrasive grains having a large grain size and is difficult to wear, because a large grinding resistance is generated during grinding. In addition, since a large grinding resistance does not occur in the cylindrical portion between both end corners of the outer peripheral surface, a grindstone layer formed of abrasive grains having a small particle size and easy to wear can be provided, which enables high finishing accuracy. . However, in the above, since the grindstone layer that is hard to wear and the grindstone layer that is easy to wear are adjacent to each other in the axial direction and grinding is performed at the same time, the degree of wear of both the grindstone layers differs, and a step occurs at the boundary. End up. For this reason, this level | step difference is transcribe | transferred to a workpiece and there exists a possibility that finishing accuracy may deteriorate.

そこで、特許文献１の研削砥石では、２種類の砥石チップによって形成された軸方向の境界部を、外周面の周方向において、図６に示すような連続した一直線形状とはせず、図３に示すように１つずつ互い違いにずれる、いわゆる千鳥状に配置している。これにより、摩耗しにくい砥石層と摩耗しやすい砥石層との間の境界部における大きな段差の発生が抑制され、延いては工作物に転写される段差の発生が抑制される。   Therefore, in the grinding wheel of Patent Document 1, the boundary in the axial direction formed by the two types of grinding wheel tips is not formed into a continuous straight line shape as shown in FIG. 6 in the circumferential direction of the outer peripheral surface. As shown in FIG. 1, they are arranged in a staggered manner, which are staggered one by one. Thereby, generation | occurrence | production of the big level | step difference in the boundary part between the grindstone layer which is hard to wear, and the grindstone layer which is easy to wear is suppressed, and also generation | occurrence | production of the level | step difference transferred to a workpiece is suppressed.

特開平１１−１８８６４０号公報Japanese Patent Laid-Open No. 11-188640

しかしながら、上述の研削砥石では、外周面の周方向において、境界部を１つずつ互い違いにずらすのみである。このため、摩耗しにくい砥石層と摩耗しやすい砥石層との間の境界部における摩耗による段差の発生を十分抑制することは困難である。   However, in the above-described grinding wheel, only the boundary portions are staggered one by one in the circumferential direction of the outer peripheral surface. For this reason, it is difficult to sufficiently suppress the occurrence of a step due to wear at the boundary between the grindstone layer that is difficult to wear and the grindstone layer that is easy to wear.

本発明は上記課題に鑑みてなされたものであり、異なる性状の砥石層が軸線方向に２種類設けられ、異なる形状の被研削部を有した工作物を良好な仕上げ精度で研削可能とする、砥石車及び砥石車の製造方法を提供することを目的とする。   The present invention has been made in view of the above problems, and two types of grindstone layers having different properties are provided in the axial direction, so that a workpiece having a portion to be ground having different shapes can be ground with good finishing accuracy. An object is to provide a grinding wheel and a method for manufacturing the grinding wheel.

本発明に係る砥石車は、円板状部材と、前記円板状部材の外周面に配置される砥石層と、を備える砥石車であって、前記砥石層は、周方向に分割される複数の周方向分割砥石チップを備え、前記複数の周方向分割砥石チップのそれぞれは、性状の異なる第一砥石チップ及び第二砥石チップが軸線方向に配列されて形成され、前記複数の周方向分割砥石チップのそれぞれにおいて前記第一砥石チップと前記第二砥石チップとの境界部は、軸線方向境界部と定義し、前記複数の周方向分割砥石チップのうち周方向に連続して配置される少なくとも３つの周方向分割砥石チップにおける前記軸線方向境界部は、周方向に連続して配置された前記少なくとも３つの周方向分割砥石チップの順に前記軸線方向の所定の方向に向かって整列している。   The grinding wheel according to the present invention is a grinding wheel comprising a disk-shaped member and a grinding wheel layer disposed on an outer peripheral surface of the disk-shaped member, and the grinding wheel layer is divided into a plurality in the circumferential direction. Each of the plurality of circumferentially divided grindstone chips, each of the plurality of circumferentially divided grindstone chips is formed by arranging first and second grindstone chips having different properties in the axial direction, and the plurality of circumferentially divided grindstone chips In each of the chips, a boundary part between the first grindstone chip and the second grindstone chip is defined as an axial boundary part, and at least three of the plurality of circumferentially divided grindstone chips are continuously arranged in the circumferential direction. The axial boundary portions of the two circumferentially divided grindstone chips are aligned in a predetermined direction in the axial direction in the order of the at least three circumferentially divided grindstone chips continuously arranged in the circumferential direction.

これにより、少なくとも３つの各周方向分割砥石チップの各軸線方向境界部は、周方向において常に２本の境界部が軸方向で互い違いに配置されるだけの従来技術に対し、外周面の周方向に向かって、軸線方向に大きな幅を有して連続的に配置される。このため、性状が異なるため発生する第一砥石チップと第二砥石チップとの間の摩耗による段差が、従来技術において、性状が異なるため発生する２種類の砥石層の間の摩耗による段差より緩やかになり、延いては工作物の仕上げ精度も良好となる。   Thereby, each axial direction boundary part of at least 3 each circumferential direction division | segmentation grindstone chip is the circumferential direction of an outer peripheral surface with respect to the prior art which only two boundary parts are always arrange | positioned alternately in an axial direction in the circumferential direction. In this case, they are continuously arranged with a large width in the axial direction. For this reason, the step due to wear between the first grindstone tip and the second grindstone tip due to different properties is more gradual than the step due to wear between the two types of grindstone layers caused by different properties in the prior art. As a result, the finishing accuracy of the workpiece is also improved.

本発明に係る砥石車の製造方法は、上記の砥石車の製造方法であり、前記円板状部材の外周面に前記複数の周方向分割砥石チップのそれぞれの前記第一及び第二砥石チップを配置することにより前記砥石層を形成する。このような製造方法によって、上記と同様の効果を得る砥石車が製造できる。   A grinding wheel manufacturing method according to the present invention is the above-described grinding wheel manufacturing method, wherein the first and second grinding wheel tips of each of the plurality of circumferentially divided grinding wheel tips are provided on an outer peripheral surface of the disk-shaped member. The said grindstone layer is formed by arrange | positioning. With such a manufacturing method, a grinding wheel can be manufactured that achieves the same effects as described above.

第一実施形態に係る砥石車を示す正面図である。It is a front view which shows the grinding wheel which concerns on 1st embodiment. 図１Ａの砥石車の側面図である。It is a side view of the grinding wheel of FIG. 1A. 周方向分割砥石チップＡ〜Ｐの表面状態を示す模式図である。It is a schematic diagram which shows the surface state of circumferential direction division grindstone chip | tip AP. 砥石層の軸線回りの展開図面である。Fig. 3 is a development drawing around the axis of the grinding wheel layer. 図３のＳ部拡大図である。It is the S section enlarged view of FIG. 第一実施形態に係る砥石車を装着した研削盤を示す図である。It is a figure which shows the grinding machine with which the grinding wheel which concerns on 1st embodiment was mounted | worn. 第一実施形態に係る砥石車と工作物Ｗとの関係を示す図である。It is a figure which shows the relationship between the grinding wheel and workpiece W which concern on 1st embodiment. 第二実施形態に係る砥石車と工作物Ｗとの関係を示す図である。It is a figure which shows the relationship between the grinding wheel and workpiece W which concern on 2nd embodiment.

＜第一実施形態＞
（砥石車の構成）
以下、本発明の砥石車の第一実施形態を図面に基づいて説明する。図１Ａに示すように、砥石車１０は、円板状ベース１３（本発明の円板状部材に相当する）と、円板状ベース１３の外周面に配置される砥石層１６と、を備える。円板状ベース１３は、鉄、アルミニウム等の金属又は樹脂等で成形される。円板状ベース１３は、砥石車１０の回転軸線回り（以降、軸線回りとのみ称す）に回転駆動される。なお、以降、特別な説明なしに軸線といった場合、砥石車１０の回転軸線のことをいう。砥石層１６は、周方向に等分に分割される複数（本実施形態では１６個）の周方向分割砥石チップＡ〜Ｐを備える。なお、砥石車１０は、例えば自動車用クランクシャフトのクランクピン、ジャーナル等のような外周に設けられた凹溝を研削対象とする総形の砥石車である。 <First embodiment>
(Configuration of grinding wheel)
Hereinafter, a first embodiment of a grinding wheel of the present invention will be described with reference to the drawings. As shown in FIG. 1A, the grinding wheel 10 includes a disk-shaped base 13 (corresponding to the disk-shaped member of the present invention), and a grindstone layer 16 disposed on the outer peripheral surface of the disk-shaped base 13. . The disk-shaped base 13 is formed of a metal such as iron or aluminum or a resin. The disc-shaped base 13 is rotationally driven around the rotation axis of the grinding wheel 10 (hereinafter, only referred to as the axis). In the following description, the term “axis” refers to the rotational axis of the grinding wheel 10 without any special explanation. The grindstone layer 16 includes a plurality (16 in this embodiment) of circumferentially divided grindstone chips AP that are equally divided in the circumferential direction. The grinding wheel 10 is a grinding wheel of a general shape that has a concave groove provided on the outer periphery, such as a crankpin of a crankshaft for an automobile, a journal, or the like, to be ground.

各周方向分割砥石チップＡ〜Ｐは、円板状ベース１３の外周面上周方向に、アルファベット順に並んで配置される。図１Ｂ、図２に示すように、各周方向分割砥石チップＡ〜Ｐは、２個の第一砥石チップ１１，１個の第二砥石チップ１２及び２個の混合部を備える。第一砥石チップ１１，第二砥石チップ１２及び混合部は、それぞれ性状の異なる砥石である。なお、各周方向分割砥石チップＡ〜Ｐが備える各２個ずつの混合部はそれぞれ同様の形状及び性状を有するが、判別するため、周方向分割砥石チップＡ〜Ｐがそれぞれ備える各混合部を混合部１８ａ〜１８ｐと称して説明する。つまり、周方向分割砥石チップＡは、混合部１８ａ，１８ａを備え、周方向分割砥石チップＢは、混合部１８ｂ，１８ｂを備える。各周方向分割砥石チップＣ〜Ｐについても同様に、それぞれ混合部１８ｃ，１８ｃ〜１８ｐ，１８ｐを備える。そして２個の第一砥石チップ１１、１個の第二砥石チップ１２及び各混合部１８ａ〜１８ｐは、各周方向分割砥石チップＡ〜Ｐにおいて、それぞれ軸線方向に予め設定された順序で整列し配列される。   Each circumferential division | segmentation grindstone chip | tip AP is arrange | positioned along with the alphabetical order on the outer peripheral surface upper peripheral direction of the disk-shaped base 13. As shown in FIG. As shown in FIG. 1B and FIG. 2, each circumferentially divided grindstone chip AP includes two first grindstone chips 11, one second grindstone chip 12, and two mixing units. The 1st whetstone tip 11, the 2nd whetstone tip 12, and a mixing part are grindstones from which a property differs, respectively. In addition, although each two mixing parts with which each circumferential direction division | segmentation grindstone chip | tip AP is provided have the same shape and property, respectively, in order to discriminate | determine, each mixing part with which each circumferential direction division | segmentation grindstone chip | tip AP is each equipped with. This will be described as mixing units 18a to 18p. That is, the circumferentially divided grindstone chip A includes mixing units 18a and 18a, and the circumferentially divided grindstone chip B includes mixing units 18b and 18b. Similarly, each of the circumferentially divided grindstone chips C to P includes mixing portions 18c, 18c to 18p, and 18p, respectively. Then, the two first grindstone chips 11, the one second grindstone chip 12, and the mixing portions 18 a to 18 p are aligned in a predetermined order in the axial direction in each circumferentially divided grindstone chip AP. Arranged.

上述の予め設定された順序について、周方向分割砥石チップＡを代表として説明する。周方向分割砥石チップＡにおいて、予め設定された順序は、第一砥石チップ１１→混合部１８ａ→第二砥石チップ１２→混合部１８ａ→第一砥石チップ１１の順である。つまり、図１Ｂに示すように各第一砥石チップ１１は、円板状ベース１３の外周面の軸線方向においてＲ形状で形成された両端の角部（Ｒ部）に配置される。第二砥石チップ１２は、外周面の軸線方向において各第一砥石チップ１１，１１の間の中央部である円筒部（Ｃ部）に配置される。そして、混合部１８ａ，１８ａは、各第一砥石チップ１１と第二砥石チップ１２との間にそれぞれ配置される。周方向分割砥石チップＢ〜Ｐについても同様である。なお、後に詳述するが、各周方向分割砥石チップＡ〜Ｐそれぞれにおいて、第一砥石チップ１１と第二砥石チップ１２との境界部は、軸線方向境界部と定義し、本実施形態においては、混合部１８ａ〜１８ｐが軸線方向境界部に相当する。   About the above-mentioned preset order, the circumferential direction division grindstone chip | tip A is demonstrated as a representative. In the circumferentially divided grindstone tip A, the preset order is the order of the first grindstone tip 11 → the mixing portion 18 a → the second grindstone tip 12 → the mixing portion 18 a → the first grindstone tip 11. That is, as shown in FIG. 1B, each first grindstone chip 11 is disposed at the corners (R portions) at both ends formed in an R shape in the axial direction of the outer peripheral surface of the disc-shaped base 13. The second grindstone tip 12 is disposed in a cylindrical portion (C portion) that is a central portion between the first grindstone tips 11 and 11 in the axial direction of the outer peripheral surface. And the mixing parts 18a and 18a are each arrange | positioned between each 1st grindstone chip | tip 11 and the 2nd grindstone chip | tip 12. FIG. The same applies to the circumferentially divided grindstone chips B to P. In addition, although explained in full detail later, in each circumferential division | segmentation grindstone chip | tip AP, the boundary part of the 1st grindstone chip | tip 11 and the 2nd grindstone chip | tip 12 is defined as an axial direction boundary part, and in this embodiment. The mixing portions 18a to 18p correspond to the axial boundary portion.

図２に示すように、第一砥石チップ１１は、ＣＢＮ、ダイヤモンド等の超砥粒１４（本発明の砥粒に相当）を結合材１５で結合し形成されたものである。なお、図２は、全周方向分割砥石チップＡ〜Ｐの表面状態を示す模式図である。第一砥石チップ１１は、一例として、粒度＃８０のＣＢＮ砥粒が、ビトリファイド結合材１５により、集中度２００で例えば４〜８ｍｍの厚さに矩形形状に結合されて成形される。従って、第一砥石チップ１１は、砥石の粒径が大きな粗研削用であり、硬度が高く比較的摩耗しにくい砥石チップである。後に詳述するが、図３に示すように、各周方向分割砥石チップＡ〜Ｐのうち、周方向で隣り合う４つずつの各周方向分割砥石チップＡ〜Ｄ、Ｅ〜Ｈ、Ｉ〜Ｌ、Ｍ〜Ｐがそれぞれ備える各４つの第一砥石チップ１１の軸線方向の幅は異なる。   As shown in FIG. 2, the first grindstone tip 11 is formed by bonding superabrasive grains 14 (corresponding to the abrasive grains of the present invention) such as CBN and diamond with a binder 15. In addition, FIG. 2 is a schematic diagram showing the surface states of the circumferentially divided grindstone chips AP. As an example, the first grindstone tip 11 is formed by bonding CBN abrasive grains having a particle size of # 80 in a rectangular shape to a thickness of, for example, 4 to 8 mm with a concentration of 200 by vitrified binder 15. Accordingly, the first grindstone tip 11 is for rough grinding with a large grindstone particle size, and is a grindstone tip that has high hardness and is relatively difficult to wear. As will be described in detail later, as shown in FIG. 3, among the circumferentially divided grindstone chips A to P, four circumferentially divided grindstone chips A to D, E to H, and I to 4 that are adjacent in the circumferential direction. The widths in the axial direction of each of the four first grindstone tips 11 provided in L and MP are different.

図２に示すように、第二砥石チップ１２は、ＣＢＮ、ダイヤモンド等の超砥粒１９（砥粒に相当）を結合材２０で結合し形成されたものである。結合材２０は、第一砥石チップ１１の結合材１５より弾性力のある結合材である。第二砥石チップ１２は、一例として、粒度＃８００のＣＢＮ砥粒が、レジノイド結合材２０により、集中度３０で例えば４〜８ｍｍの厚さに矩形形状に結合されて成形される。レジノイド結合材２０としては、例えばフェノール樹脂が使用される。   As shown in FIG. 2, the second grindstone tip 12 is formed by bonding superabrasive grains 19 (corresponding to abrasive grains) such as CBN and diamond with a binder 20. The binding material 20 is a binding material having elasticity more than the binding material 15 of the first grindstone chip 11. As an example, the second grindstone tip 12 is formed by bonding CBN abrasive grains having a particle size of # 800 in a rectangular shape to a thickness of, for example, 4 to 8 mm with a concentration of 30 by the resinoid binder 20. As the resinoid binder 20, for example, a phenol resin is used.

従って、第二砥石チップ１２は、砥石の粒径が小さな仕上げ研削用であり、硬度が低く比較的摩耗しやすい砥石チップである。後に詳述するが、図３に示すように、各周方向分割砥石チップＡ〜Ｐのうち、周方向で隣り合う４つずつの各周方向分割砥石チップＡ〜Ｄ、Ｅ〜Ｈ、Ｉ〜Ｌ、Ｍ〜Ｐがそれぞれ備える各４つの第二砥石チップ１２の軸線方向の幅は異なる。   Therefore, the second grindstone tip 12 is for finish grinding with a small grindstone particle size, and is a grindstone tip with low hardness and relatively easy wear. As will be described in detail later, as shown in FIG. 3, among the circumferentially divided grindstone chips A to P, four circumferentially divided grindstone chips A to D, E to H, and I to 4 that are adjacent in the circumferential direction. The widths in the axial direction of each of the four second grindstone chips 12 provided in L and MP are different.

図２に示すように、混合部１８ａ〜１８ｐは、第二砥石チップ１２が有する粒度＃８００の例えばＣＢＮ砥粒（超砥粒１９）と、第一砥石チップ１１が有する粒度＃８０の例えばＣＢＮ砥粒（超砥粒１４）とが、ほぼ均一に混在した砥石部分である。混合部１８ａ〜１８ｐでは、ビトリファイド結合材１５及びレジノイド結合材２０も混在している。よって、混合部１８ａ〜１８ｐは、第一砥石チップ１１と第二砥石チップ１２の両方の特性を有しており、摩耗のし易さは、第一砥石チップ１１と第二砥石チップ１２とのほぼ中間であるといえる。混合部１８ａ〜１８ｐの軸線方向の幅は、各超砥粒１４、１９が１〜２個分収容可能な幅であることが好ましい。なお、各混合部１８ａ〜１８ｐの各軸線方向幅Ｌａ（図３の展開図参照）は、ほぼ同じであるものとする。また、混合部１８ａ〜１８ｐの厚さは、第一砥石チップ１１、及び第二砥石チップ１２とほぼ同じであるものとする。   As shown in FIG. 2, the mixing units 18 a to 18 p include, for example, CBN abrasive grains (super abrasive grains 19) having a particle size # 800 of the second grindstone chip 12 and CBN grains having a particle size # 80 of the first grindstone chip 11. Abrasive grains (superabrasive grains 14) are parts of a grindstone where they are mixed almost uniformly. In the mixing portions 18a to 18p, the vitrified binder 15 and the resinoid binder 20 are also mixed. Therefore, the mixing portions 18a to 18p have the characteristics of both the first grindstone tip 11 and the second grindstone tip 12, and the ease of wear is determined between the first grindstone tip 11 and the second grindstone tip 12. It can be said that it is almost in the middle. The width in the axial direction of the mixing portions 18a to 18p is preferably a width that can accommodate one or two superabrasive grains 14 and 19. In addition, each axial direction width | variety La (refer the expanded view of FIG. 3) of each mixing part 18a-18p shall be substantially the same. Moreover, the thickness of the mixing parts 18a-18p shall be substantially the same as the 1st whetstone chip 11 and the 2nd whetstone chip 12. FIG.

このように形成された同じ厚さの各砥石チップ１１、１２，１１及び混合部１８ａ〜１８ｐが、円板状ベース１３の外周面に軸線方向に上記で説明した順番で並べられて周方向分割砥石チップＡ〜Ｐがそれぞれ形成される。   The grindstone chips 11, 12, 11 and the mixing portions 18 a to 18 p having the same thickness formed in this way are arranged in the order described above in the axial direction on the outer peripheral surface of the disc-shaped base 13 and divided in the circumferential direction. Grinding stone tips A to P are respectively formed.

（混合部１８ａ〜１８ｐのオーバーラップについて）
前述した図３は、円板状ベース１３の外周面の砥石層１６を軸線周りに展開した展開図である。ここでは、周方向で隣り合う各混合部１８ａ〜１８ｐのオーバーラップについて説明するため、周方向分割砥石チップＡ〜Ｄを抜き出し代表として説明する。図３のＳ部拡大図である図４に示すように、周方向分割砥石チップＡが備える図１Ｂの右側の混合部１８ａと、周方向分割砥石チップＡと周方向で隣接する周方向分割砥石チップＢが備える軸線方向境界部のうち前記右側の混合部１８ａに対応する図１Ｂの右側の混合部１８ｂとは、各混合部１８ａ、１８ｂの軸線方向における幅Ｌａの各中央位置（中心線ＣＬ参照）同士が、一致しないよう配置されている。また、図４に示すように、混合部１８ａと混合部１８ｂとは、円板状ベース１３の軸線方向において所定量αだけオーバーラップするよう配置されている。 (About overlap of mixing parts 18a-18p)
FIG. 3 described above is a developed view in which the grindstone layer 16 on the outer peripheral surface of the disk-shaped base 13 is developed around the axis. Here, in order to explain the overlap of the mixing portions 18a to 18p adjacent in the circumferential direction, the circumferentially divided grindstone chips A to D will be described as representative representatives. As shown in FIG. 4, which is an enlarged view of the S part in FIG. 3, the right-side mixing unit 18 a of FIG. 1B provided in the circumferential division grindstone chip A, and the circumferential division grindstone adjacent to the circumferential division grindstone chip A in the circumferential direction. The right side mixing unit 18b in FIG. 1B corresponding to the right side mixing unit 18a among the axial direction boundaries provided in the chip B is the center position (center line CL) of the width La in the axial direction of each mixing unit 18a, 18b. References) are arranged so as not to match each other. As shown in FIG. 4, the mixing unit 18 a and the mixing unit 18 b are arranged so as to overlap each other by a predetermined amount α in the axial direction of the disc-shaped base 13.

また、周方向で隣り合う各混合部１８ｂと１８ｃ、及び１８ｃと１８ｄの各混合部相互間の配置も、混合部１８ａと混合部１８ｂとの間と同様の関係を有する。さらには、他の混合部１８ｅ〜１８ｐも、周方向で隣り合う各混合部相互間の配置は、混合部１８ａと混合部１８ｂとの間と同様の関係を有する。ただし、オーバーラップする所定量αの大きさは、同じでなくてもよい。   In addition, the arrangement between the mixing portions 18b and 18c and the mixing portions 18c and 18d adjacent in the circumferential direction has the same relationship as that between the mixing portion 18a and the mixing portion 18b. Furthermore, the other mixing units 18e to 18p also have the same arrangement between the mixing units adjacent in the circumferential direction as between the mixing unit 18a and the mixing unit 18b. However, the size of the predetermined amount α that overlaps may not be the same.

なお、以降において、各周方向分割砥石チップＡ〜Ｐが、それぞれ２個ずつ有する各混合部１８ａ〜１８ｐを説明する場合、特別な断りがない限り、説明は、図３における右側の混合部１８ａ〜１８ｐのみについて説明するものとする。   In the following description, when each of the circumferentially divided grindstone chips A to P describes each of the mixing units 18a to 18p having two each, unless otherwise specified, the description is provided on the right mixing unit 18a in FIG. Only ˜18p will be described.

また、図３、図４に示すように、本実施形態では、外周面の周方向に連続して配置された各４個（少なくとも３つに相当）の周方向分割砥石チップＡ〜Ｄ、及びＩ〜Ｌの各混合部１８ａ〜１８ｄ、及び１８ｉ〜１８ｌの軸線方向の各中央位置は、各４個の各周方向分割砥石チップＡ〜Ｄ、及びＩ〜Ｌが周方向に連続して配置された順に、図３、図４において軸線方向における左方向（所定の方向に相当）に向かって整列している。   In addition, as shown in FIGS. 3 and 4, in this embodiment, each of four (at least three) circumferentially divided grindstone chips A to D arranged continuously in the circumferential direction of the outer peripheral surface, and At each central position in the axial direction of each of the mixing portions 18a to 18d and 18i to 18l of I to L, each of the four circumferentially divided grindstone chips A to D and I to L is continuously arranged in the circumferential direction. 3 and 4, they are aligned toward the left direction (corresponding to a predetermined direction) in the axial direction.

また、外周面の周方向に連続して配置された４個（少なくとも３つに相当）の各周方向分割砥石チップＥ〜Ｈ、及びＭ〜Ｐの各混合部１８ｅ〜１８ｈ、及び１８ｍ〜１８ｐの軸線方向の各中央位置は、各４個の各周方向分割砥石チップＥ〜Ｈ、及びＭ〜Ｐが周方向に連続して配置された順に、図３、図４において軸線方向における右方向（所定の方向）に向かって整列している。このような周方向分割砥石チップＡ〜Ｐの配置によって、各混合部１８ａ〜１８ｐは軸線方向に大きな幅を有して連続的で曲線的な大きなうねり形状を形成することができる。   Moreover, each of the circumferentially divided grindstone chips E to H and M to P mixed portions 18e to 18h and 18m to 18p arranged continuously in the circumferential direction of the outer peripheral surface. Each of the center positions in the axial direction of each of the four circumferential direction divided grindstone chips E to H and M to P is arranged in the order in which the circumferential direction is continuously arranged in the circumferential direction in FIGS. 3 and 4. They are aligned toward (predetermined direction). Due to the arrangement of the circumferentially divided grindstone chips A to P, each of the mixing portions 18a to 18p can have a large width in the axial direction and form a continuous and large wavy shape.

このような曲線的なうねり形状は、外周面の周方向において隣り合う各混合部１８ａ〜１８ｐ間の軸線方向のオーバーラップの各所定量αを調整することによって自在に得られる。うねりの形状は、実際に研削実験を行ない、混合部１８ａ〜１８ｐに発生する摩耗量が良好に抑制される形状を選択すればよく、その形状はどのようなものでもよい。この場合、各混合部１８ａ〜１８ｐの軸線方向の各中央位置（ＣＬ）における、例えば周方向中点同士を各混合部１８ａ〜１８ｐの添え字のアルファベット順に滑らかにつないだ場合、ＳＩＮカーブとなるよう各混合部１８ａ〜１８ｐを配置してもよい。   Such a curved waviness shape can be freely obtained by adjusting each predetermined amount α of the overlap in the axial direction between the mixing portions 18a to 18p adjacent in the circumferential direction of the outer peripheral surface. The shape of the waviness may be any shape as long as the amount of wear generated in the mixing portions 18a to 18p is satisfactorily suppressed by actually performing a grinding experiment. In this case, for example, when the middle points in the circumferential direction at the respective center positions (CL) in the axial direction of the mixing portions 18a to 18p are smoothly connected in the alphabetical order of the subscripts of the mixing portions 18a to 18p, a SIN curve is obtained. The mixing units 18a to 18p may be arranged as described above.

また、図１Ｂに示すように、第一砥石チップ１１と第二砥石チップ１２との間に形成される各混合部１８ａ〜１８ｐ（軸線方向境界部）は、円板状ベース１３の外周面において、外周面の軸線方向における両端の各Ｒ部の一部に配置される。つまり、第一砥石チップ１１，１１は、各Ｒ部の一部に配置され、第二砥石チップ１２は、円筒部（Ｃ部）及び各Ｒ部の残りの一部に配置される。   Further, as shown in FIG. 1B, each mixing portion 18 a to 18 p (axial boundary portion) formed between the first grindstone tip 11 and the second grindstone tip 12 is formed on the outer peripheral surface of the disc-shaped base 13. , Are arranged in a part of each R portion at both ends in the axial direction of the outer peripheral surface. In other words, the first grindstone tips 11 and 11 are arranged in a part of each R part, and the second grindstone chip 12 is arranged in a cylindrical part (C part) and the remaining part of each R part.

なお、上記においては、各周方向分割砥石チップＡ〜Ｐがそれぞれ２個ずつ有する各混合部１８ａ〜１８ｐのうち、図３における右側の混合部１８ａ〜１８ｐのみについて説明した。しかし、図３における左側の混合部１８ａ〜１８ｐも同様に形成されている。   In addition, in the above, only the mixing parts 18a-18p of the right side in FIG. 3 were demonstrated among each mixing part 18a-18p which each circumferential direction division grindstone chip | tip AP has two each. However, the left mixing portions 18a to 18p in FIG. 3 are also formed in the same manner.

（周方向分割砥石チップＡ〜Ｐの製造方法）
次に、周方向分割砥石チップＡ〜Ｐの製造方法について説明する。第一砥石チップ１１を製造するため、まず超砥粒１４および結合材１５等を混合した粉体が、凹矩形形状のプレス下型上に均一厚さに充填される。その後、プレス下型上に充填された粉体が、第１上型によりプレスされて砥石チップが矩形状に成形される。そして、プレス成形された砥石チップが乾燥され、乾燥後に焼成されて第一砥石チップ１１が完成する。なお、第二砥石チップ１２についても、超砥粒１４および結合材１５が、超砥粒１９および結合材２０に変更されるだけであり、第一砥石チップ１１と同様の方法によって製造される。 (Manufacturing method of circumferential direction division grindstone chip AP)
Next, the manufacturing method of circumferential direction division grindstone chip | tip AP is demonstrated. In order to manufacture the first grindstone chip 11, first, a powder obtained by mixing the superabrasive grains 14, the binder 15, and the like is filled on the concave rectangular press lower die with a uniform thickness. Thereafter, the powder filled on the lower press mold is pressed by the first upper mold, and the grindstone chip is formed into a rectangular shape. Then, the press-molded grindstone chip is dried, fired after drying, and the first grindstone chip 11 is completed. The second grindstone chip 12 is also manufactured by the same method as the first grindstone chip 11 except that the superabrasive grains 14 and the bonding material 15 are changed to the superabrasive grains 19 and the bonding material 20.

混合部１８ａ〜１８ｐは、第一砥石チップ１１と第二砥石チップ１２との境界部を相互に接触させた状態で焼成することにより製作する。焼成した第一砥石チップ１１，第二砥石チップ１２の接触部分近傍では、結合材１５及び結合材２０が溶融する。このような状態で、各第一砥石チップ１１，及び第二砥石チップ１２の各超砥粒１４、１９が混ざり合い混合部１８ａ〜１８ｐが形成される。   The mixing portions 18a to 18p are manufactured by firing in a state where the boundary portions between the first grindstone tip 11 and the second grindstone tip 12 are in contact with each other. In the vicinity of the contact portion between the fired first grindstone chip 11 and second grindstone chip 12, the bonding material 15 and the bonding material 20 are melted. In such a state, the superabrasive grains 14 and 19 of the first grindstone tips 11 and the second grindstone tips 12 are mixed to form the mixing portions 18a to 18p.

このように形成された各周方向分割砥石チップＡ〜Ｐは、前述した配置の規則に従って円板状ベース１３の外周面の周方向全周に接着剤（図略）により連続的に貼付される。   The circumferentially divided grindstone chips A to P formed in this way are continuously stuck with an adhesive (not shown) on the entire circumference in the circumferential direction of the outer peripheral surface of the disc-shaped base 13 in accordance with the arrangement rules described above. .

（研削盤２５の構成）
次に、砥石車１０が装着されて工作物Ｗを研削加工する研削盤２５について図５に基づいて説明する。図５に示すように、ベッド２６上には、テーブル２７が摺動可能に載置され、サーボモータ２８によりボールネジを介してＺ軸方向に移動される。テーブル２７上には、主軸台２９と心押台３０とが対向して取り付けられ、主軸台２９と心押台３０との間に工作物ＷがＺ軸方向にセンタ支持される。主軸台２９には主軸３１が回転可能に軸承され、サーボモータ３２により回転駆動される。工作物Ｗは主軸３１にケレ回し等により連結されて回転駆動される。 (Configuration of grinding machine 25)
Next, the grinding machine 25 to which the grinding wheel 10 is mounted to grind the workpiece W will be described with reference to FIG. As shown in FIG. 5, a table 27 is slidably mounted on the bed 26 and is moved in the Z-axis direction by a servo motor 28 via a ball screw. A spindle stock 29 and a tailstock 30 are mounted on the table 27 so as to face each other, and the workpiece W is center-supported in the Z-axis direction between the spindle stock 29 and the tailstock 30. A spindle 31 is rotatably supported on the spindle stock 29 and is driven to rotate by a servo motor 32. The workpiece W is connected to the main shaft 31 by rotation or the like and rotated.

ベッド２６上には、砥石台３４が摺動可能に載置され、サーボモータ３５によりボールネジを介してＺ軸と直角に交差するＸ軸方向に移動される。砥石台３４には砥石軸３６が回転可能に軸承され、ビルトインモータ３７により回転駆動される。砥石軸３６の先端には砥石車１０の円板状ベース１３に穿設された中心穴３８が嵌合されてボルトにより固定されている。   A grinding wheel base 34 is slidably mounted on the bed 26, and is moved by a servo motor 35 in the X-axis direction that intersects the Z-axis at right angles via a ball screw. A grinding wheel shaft 36 is rotatably supported on the grinding wheel base 34 and is driven to rotate by a built-in motor 37. A center hole 38 drilled in the disc-shaped base 13 of the grinding wheel 10 is fitted to the tip of the grinding wheel shaft 36 and fixed by bolts.

ＣＮＣ装置４０は、サーボモータ２８，３２，３５及びビルトインモータ３７の駆動回路４１乃至４４に接続されている。ＣＮＣ装置４０は、研削加工時に研削加工用ＮＣプログラムを順次実行して砥石車１０に工作物Ｗを研削加工させる。   The CNC device 40 is connected to the drive circuits 41 to 44 of the servo motors 28, 32 and 35 and the built-in motor 37. The CNC device 40 sequentially executes the NC program for grinding at the time of grinding to cause the grinding wheel 10 to grind the workpiece W.

（研削盤の作動について）
ＣＮＣ装置４０は、砥石車１０に工作物Ｗを研削加工させるときは、研削加工用ＮＣプログラムを実行し、砥石車１０を高速回転速度で回転させる回転指令を、ビルトインモータ３７の駆動回路４４に出力する。また、ＣＮＣ装置４０は、工作物Ｗを研削加工に適した周速度で回転させる回転指令を、主軸３１を回転駆動するサーボモータ３２の駆動回路４２に出力する。次に、工作物Ｗが砥石車１０と対向する位置にテーブル２７をＺ軸方向に移動させる送り指令が、サーボモータ２８の駆動回路４１に出力される。 (About the operation of the grinding machine)
When the grinding wheel 10 is ground by the grinding wheel 10, the CNC device 40 executes a grinding NC program and sends a rotation command to rotate the grinding wheel 10 at a high rotational speed to the drive circuit 44 of the built-in motor 37. Output. Further, the CNC device 40 outputs a rotation command for rotating the workpiece W at a peripheral speed suitable for grinding to the drive circuit 42 of the servo motor 32 that rotationally drives the main shaft 31. Next, a feed command for moving the table 27 in the Z-axis direction to a position where the workpiece W faces the grinding wheel 10 is output to the drive circuit 41 of the servo motor 28.

砥石車１０が工作物Ｗの研削箇所と対向すると、砥石台３４をＸ軸方向に粗研削送り速度で前進移動させる指令が、サーボモータ３５の駆動回路４３に出力される。これにより、砥石車１０は、図略のクーラントノズルからクーラントを供給されながら工作物Ｗを研削加工する。   When the grinding wheel 10 faces the grinding part of the workpiece W, a command for moving the grinding wheel base 34 forward in the X-axis direction at a rough grinding feed rate is output to the drive circuit 43 of the servo motor 35. Thereby, the grinding wheel 10 grinds the workpiece W while being supplied with coolant from a coolant nozzle (not shown).

次に、砥石車１０によって工作物Ｗを研削する場合について詳細に説明する。前述したとおり、工作物Ｗはクランクシャフトであり、研削する部位は、クランクシャフトの凹部である、例えば、図６に示すクランクジャーナル４５及びクランクジャーナルの回転軸方向両側面４６，４７である。以後、クランクジャーナル４５及び回転軸方向両側面４６，４７は、凹部とのみ称す場合がある。図６に示すように、砥石車１０は、総形の研削砥石であり、凹部よりも軸線方向（Ｚ軸方向）において若干大きな形状を有している。このため、砥石車１０が、凹部内に切り込まれると、砥石車１０は、摩耗のしにくい第一砥石チップ１１を備えた軸線方向両端部（Ｒ部）で、凹部の両側面４６，４７（斜線部）を研削によって除去加工しながら切り込む。そして、砥石車１０の外周面の円筒部（Ｃ部）が、凹部の底面であるクランクジャーナル４５の外周面に到達すると、摩耗し易い第二砥石チップ１２によって、凹部の底面（クランクジャーナル４５の外周面）が研削され、仕上げ加工が行なわれる。   Next, the case where the workpiece W is ground by the grinding wheel 10 will be described in detail. As described above, the workpiece W is a crankshaft, and the parts to be ground are, for example, the crank journal 45 shown in FIG. 6 and both sides 46 and 47 of the crank journal in the rotation axis direction. Hereinafter, the crank journal 45 and both side surfaces 46 and 47 in the direction of the rotation axis may be referred to only as recesses. As shown in FIG. 6, the grinding wheel 10 is an overall grinding wheel, and has a slightly larger shape in the axial direction (Z-axis direction) than the recess. For this reason, when the grinding wheel 10 is cut into the recess, the grinding wheel 10 is at both axial ends (R portion) provided with the first grinding wheel tip 11 that is difficult to wear, and both side surfaces 46, 47 of the recess. Cut while removing (shaded area) by grinding. Then, when the cylindrical portion (C portion) on the outer peripheral surface of the grinding wheel 10 reaches the outer peripheral surface of the crank journal 45 which is the bottom surface of the concave portion, the bottom surface of the concave portion (the The outer peripheral surface) is ground and finished.

このとき、周方向分割砥石チップＡ〜Ｐの混合部１８ａ〜１８ｐは、砥石車１０の外周面の周方向において、曲線状のうねりを有して形成されている。つまり、混合部１８ａ〜１８ｐは、工作物Ｗの研削時に摩耗が抑制されやすい形状にて形成されている。このため、摩耗による、摩耗しにくい第一砥石チップ１１と摩耗し易い第二砥石チップ１２との間の混合部１８ａ〜１８ｐの段差の発生は、効果的に抑制される。   At this time, the mixing portions 18 a to 18 p of the circumferentially divided grindstone chips A to P are formed with curved waviness in the circumferential direction of the outer peripheral surface of the grinding wheel 10. That is, the mixing portions 18a to 18p are formed in a shape in which wear is easily suppressed when the workpiece W is ground. For this reason, generation | occurrence | production of the level | step difference of the mixing parts 18a-18p between the 1st whetstone chip 11 which is hard to wear, and the 2nd whetstone chip 12 which is easy to wear by wear is suppressed effectively.

また、図１Ｂに示すように、第一砥石チップ１１と第二砥石チップ１２との間に形成される各混合部１８ａ〜１８ｐ（軸線方向境界部）は、外周面において、外周面の軸線方向における両端の各Ｒ部の一部に配置される。つまり、第一砥石チップ１１，１１は、各Ｒ部の一部に配置され、第二砥石チップ１２は、円筒部及び各Ｒ部の残りの一部に配置される。このため、円筒部（Ｃ部）には混合部１８ａ〜１８ｐが配置されない。従って、混合部１８ａ〜１８ｐに摩耗が発生し段差が生じても、円筒部（Ｃ部）に設けられる第二砥石チップ１２によって研削される工作物Ｗの凹部の底面（クランクジャーナル４５の外周面）には、前記段差は転写されず、良好な仕上げ精度を得ることができる。   Moreover, as shown to FIG. 1B, each mixing part 18a-18p (axial direction boundary part) formed between the 1st grindstone chip | tip 11 and the 2nd grindstone chip | tip 12 is an axial direction of an outer peripheral surface in an outer peripheral surface. It is arranged in a part of each R part of both ends in. That is, the first grindstone tips 11 and 11 are arranged in a part of each R part, and the second grindstone chip 12 is arranged in a cylindrical part and the remaining part of each R part. For this reason, the mixing parts 18a-18p are not arrange | positioned at a cylindrical part (C part). Therefore, even if wear occurs in the mixing portions 18a to 18p and a level difference occurs, the bottom surface of the concave portion of the workpiece W to be ground by the second grindstone tip 12 provided in the cylindrical portion (C portion) (the outer peripheral surface of the crank journal 45). ) Is not transferred, and good finishing accuracy can be obtained.

（実施形態における効果）
上記説明から明らかなように、第一実施形態によれば、砥石車１０は、円板状ベース１３（円板状部材）と、円板状ベース１３の外周面に配置される砥石層１６と、を備える砥石車１０であって、砥石層１６は、周方向に分割される複数（１６個）の周方向分割砥石チップＡ〜Ｐを備え、各周方向分割砥石チップＡ〜Ｐのそれぞれは、性状の異なる第一砥石チップ１１及び第二砥石チップ１２が軸線方向に配列されて形成される。複数（１６個）の周方向分割砥石チップＡ〜Ｐのそれぞれにおいて第一砥石チップ１１と第二砥石チップ１２との境界部は、軸線方向境界部と定義する。そして、複数（１６個）の周方向分割砥石チップＡ〜Ｐのうち周方向に連続して配置される各４個（少なくとも３つ）の周方向分割砥石チップＡ〜Ｄ、及びＩ〜Ｌ、または周方向分割砥石チップＥ〜Ｈ、及びＭ〜Ｐにおける軸線方向境界部は、周方向に連続して配置された各４個（少なくとも３つ）の周方向分割砥石チップＡ〜Ｄ、及びＩ〜Ｌまたは周方向分割砥石チップＥ〜Ｈ、及びＭ〜Ｐの順に軸線方向の所定の方向に向かって整列している。 (Effect in embodiment)
As is clear from the above description, according to the first embodiment, the grinding wheel 10 includes a disk-shaped base 13 (disk-shaped member), and a grinding wheel layer 16 disposed on the outer peripheral surface of the disk-shaped base 13. The grindstone wheel 16 includes a plurality (16 pieces) of circumferentially divided grindstone chips A to P divided in the circumferential direction, and each of the circumferentially divided grindstone chips A to P is provided. The first grindstone tip 11 and the second grindstone tip 12 having different properties are arranged in the axial direction. The boundary between the first grindstone tip 11 and the second grindstone tip 12 in each of the plural (16) circumferentially divided grindstone tips A to P is defined as an axial boundary. And each of four (at least three) circumferentially divided grindstone chips A to D and I to L arranged continuously in the circumferential direction among a plurality (16) of circumferentially divided grindstone chips A to P, Or the axial direction boundary part in circumferential direction division grindstone chip EH and MP is each four (at least 3) circumferential direction division grindstone chips AD arranged continuously in the circumferential direction, and I. ˜L or circumferentially divided grindstone chips E to H, and M to P are aligned in the axial direction in a predetermined direction.

これにより、各４個（少なくとも３つ）の各周方向分割砥石チップＡ〜Ｄ、及びＩ〜Ｌまたは周方向分割砥石チップＥ〜Ｈ、及びＭ〜Ｐの各軸線方向境界部は、周方向において常に２本の境界部が軸方向で互い違いに配置されるだけの従来技術に対し、外周面の周方向に向かって、軸線方向に大きな幅を有して連続的に配置される。このため、性状が異なるため発生する第一砥石チップ１１と第二砥石チップ１２との間の摩耗による段差は、従来技術における、性状が異なるため発生する２種類の砥石層の間の摩耗による段差より緩やかなものにでき、延いては工作物Ｗの仕上げ精度も良好なものとすることができる。   As a result, each of the four (at least three) circumferentially divided grindstone tips A to D and I to L or the circumferentially divided grindstone chips E to H and M to P has an axial boundary portion in the circumferential direction. In contrast to the conventional technique in which two boundary portions are always alternately arranged in the axial direction, the two boundary portions are continuously arranged with a large width in the axial direction toward the circumferential direction of the outer peripheral surface. For this reason, the level | step difference by abrasion between the 1st grindstone chip | tip 11 and the 2nd grindstone chip | tip 12 which generate | occur | produces because a property differs is a level | step difference by abrasion between two types of grindstone layers which generate | occur | produce in the prior art because of a different property. It can be made more gradual, and the finishing accuracy of the workpiece W can also be improved.

また、第一、第二砥石チップ１１、１２の各性状（砥石の粒径、硬度、結合材の種類など）の異なり度合いによって、第一砥石チップ１１と第二砥石チップ１２との間に発生する摩耗による段差の度合いに差が生じる。このときには、砥石車１０の周方向に連続して配置される分割砥石チップＡ〜Ｐの各軸線方向境界部の軸方向位置の変化量を段差の度合いに応じて変更すればよい。例えば、段差が大き過ぎるときには、各軸線方向境界部の軸方向位置の変化量、即ち、周方向で隣り合う各軸線方向境界部の軸線方向におけるオーバーラップの各所定量αを小さくし、かつ軸方向における軸線方向境界部の変化幅をより広げるよう変更すればよい。また、段差が小さいときには、各軸線方向境界部の軸方向位置の変化量である軸線方向のオーバーラップの各所定量αを大きくしてもよい。このようにすることで、摩耗による砥石層１６の段差を効率的に分散でき、工作物Ｗの仕上げ精度をより良好なものとすることができる。   Moreover, it occurs between the first grindstone tip 11 and the second grindstone tip 12 depending on the degree of difference between the properties of the first and second grindstone tips 11 and 12 (grain size, hardness, type of binder, etc.). There is a difference in the level of the step due to wear. At this time, the amount of change in the axial position of each axial boundary portion of the divided grinding wheel chips A to P continuously arranged in the circumferential direction of the grinding wheel 10 may be changed according to the degree of the step. For example, when the step is too large, the amount of change in the axial position of each axial boundary portion, that is, each predetermined amount α of overlap in the axial direction of each axial boundary portion adjacent in the circumferential direction is reduced, and the axial direction What is necessary is just to change so that the change width of the axial direction boundary part in may be expanded more. When the level difference is small, each predetermined amount α of the overlap in the axial direction, which is the amount of change in the axial position of each axial boundary, may be increased. By doing in this way, the level | step difference of the grindstone layer 16 by abrasion can be disperse | distributed efficiently, and the finishing precision of the workpiece W can be made more favorable.

また、第一実施形態によれば、第一砥石チップ１１は、砥粒の粒径が大きくて硬度が高く、第二砥石チップ１２は、砥粒の粒径が小さくて硬度が低く、第一砥石チップ１１は、砥石層１６の軸線方向の両端部に配置され、第二砥石チップ１２は、砥石層１６の軸線方向の中央部に配置されている。   Further, according to the first embodiment, the first grindstone tip 11 has a large grain size and high hardness, and the second grindstone tip 12 has a small grain size and low hardness. The grindstone tip 11 is disposed at both ends in the axial direction of the grindstone layer 16, and the second grindstone chip 12 is disposed at the central portion in the axial direction of the grindstone layer 16.

これにより、例えば、外周全周に凹部を備えた円柱状の工作物Ｗの凹部を研削する際、良好に研削できる。つまり、研削量が多く研削抵抗の大きな凹部の内側側面は、砥粒の粒径が大きく硬度が高い第一砥石チップ１１による砥石層１６によって研削するので、砥石層１６の摩耗が抑制される。また、研削抵抗が小さな凹部の底面を砥粒の粒径が小さく硬度が低い第二砥石チップ１２による砥石層１６によって研削するので、仕上げ精度が向上する。   Thereby, for example, when the concave portion of the columnar workpiece W provided with the concave portion on the entire outer periphery is ground, the grinding can be favorably performed. That is, the inner side surface of the recess having a large amount of grinding and a large grinding resistance is ground by the grindstone layer 16 of the first grindstone tip 11 having a large grain size and high hardness, so that wear of the grindstone layer 16 is suppressed. In addition, since the bottom surface of the recess having a small grinding resistance is ground by the grindstone layer 16 of the second grindstone tip 12 having a small grain size and low hardness, the finishing accuracy is improved.

また、第一実施形態によれば、砥石層１６は、円筒部（Ｃ部）と、円筒部（Ｃ部）の両端に配置される各Ｒ部とを備え、第一砥石チップ１１は、各Ｒ部の一部に配置され、第二砥石チップ１２は、円筒部及び各Ｒ部の残りの一部に配置され、軸線方向境界部は、各Ｒ部の一部に配置される。このとき、各Ｒ部の一部は工作物Ｗの円筒外周面に直接接触しない。このため、各Ｒ部の一部に形成される軸線方向境界部に摩耗による段差が発生しても、工作物Ｗの円筒外周面には段差が転写されず、仕上げ精度が良好となる。   Moreover, according to 1st embodiment, the grindstone layer 16 is provided with a cylindrical part (C part) and each R part arrange | positioned at the both ends of a cylindrical part (C part), and the 1st grindstone chip | tip 11 is each Arranged in a part of the R part, the second grindstone tip 12 is arranged in the cylindrical part and the remaining part of each R part, and the axial boundary part is arranged in a part of each R part. At this time, a part of each R part does not contact the cylindrical outer peripheral surface of the workpiece W directly. For this reason, even if a step due to wear occurs at the axial boundary formed in a part of each R portion, the step is not transferred to the cylindrical outer peripheral surface of the workpiece W, and the finishing accuracy is improved.

また、第一実施形態によれば、各軸線方向境界部は軸線方向に所定の幅を有し、当該所定の幅の中には各軸線方向境界部の軸線方向両端に配置された性状の異なる第一、第二砥石チップ１１、１２の各砥粒が混在して混合部１８ａ〜１８ｐを形成する。   Further, according to the first embodiment, each axial boundary portion has a predetermined width in the axial direction, and in the predetermined width, the properties arranged at both axial ends of each axial direction boundary portion are different. The abrasive grains of the first and second grindstone chips 11 and 12 are mixed to form the mixing portions 18a to 18p.

混合部１８ａ〜１８ｐでは、性状の異なる２種の砥粒１４、１９が混在しているので、混合部１８ａ〜１８ｐの摩耗量は混合部１８ａ〜１８ｐの軸線方向両側の各第一、第二砥石チップ１１、１２の各摩耗量の間の大きさとなる。このため、摩耗後において、混合部１８ａ〜１８ｐは、混合部１８ａ〜１８ｐの両側の各第一、第二砥石チップ１１、１２を緩やかな傾斜で接続し、各第一、第二砥石チップ１１、１２間における急傾斜な段差の発生を効果的に抑制する。   Since two types of abrasive grains 14 and 19 having different properties are mixed in the mixing portions 18a to 18p, the wear amount of the mixing portions 18a to 18p is the first and second on both sides in the axial direction of the mixing portions 18a to 18p. It becomes a size between the wear amounts of the grindstone tips 11 and 12. For this reason, after wear, the mixing portions 18a to 18p connect the first and second grindstone tips 11 and 12 on both sides of the mixing portions 18a to 18p with a gentle inclination, and the first and second grindstone tips 11 are connected. , 12 is effectively suppressed from occurring.

また、第一実施形態によれば、各混合部１８ａ〜１８ｐは円板状ベース１３（円板状部材）の外周面の周方向において隣接する混合部との軸線方向におけるオーバーラップ量（所定量α）が変化される。   Moreover, according to 1st embodiment, each mixing part 18a-18p is the overlap amount (predetermined amount) in the axial direction with the adjacent mixing part in the circumferential direction of the outer peripheral surface of the disk-shaped base 13 (disk-shaped member). α) is changed.

このように、各混合部１８ａ〜１８ｐ間のオーバーラップの所定量αを変化させることによって、軸線方向境界部を円板状ベース１３の外周面の周方向に連続的に接続する形状を外周面の周方向に向かって所望の形状にできる。例えば、各混合部１８ａ〜１８ｐの軸線方向の各中央位置における周方向の各中点を各混合部１８ａ〜１８ｐの添え字のアルファベット順に滑らかにつないだ際、つないだ曲線がＳＩＮカーブを形成するようオーバーラップの所定量αを調整して各混合部１８ａ〜１８ｐを配置してもよい。これにより、摩耗によって、性状が異なる第一砥石チップ１１と第二砥石チップ１２との間で発生する段差を、所望の形状、大きさとすることができ、延いては工作物Ｗの仕上げ精度が非常に良好なものとなる。また、上記効果と、段差を緩やかな傾斜とする各混合部１８ａ〜１８ｐ自体が有する効果とが複合されると、その効果はさらに大きくなる。   Thus, by changing the predetermined amount α of the overlap between the mixing portions 18a to 18p, the shape that continuously connects the axial boundary portion in the circumferential direction of the outer peripheral surface of the disc-shaped base 13 is changed to the outer peripheral surface. It can be made into a desired shape toward the circumferential direction. For example, when each middle point in the circumferential direction at each central position in the axial direction of each mixing unit 18a-18p is smoothly connected in alphabetical order of the subscripts of each mixing unit 18a-18p, the connected curve forms a SIN curve. The mixing portions 18a to 18p may be arranged by adjusting the predetermined amount α of overlap. Thereby, the level | step difference which generate | occur | produces between the 1st grindstone chip | tip 11 and the 2nd grindstone chip | tip 12 from which a property differs by abrasion can be made into a desired shape and magnitude | size, and the finishing precision of the workpiece W is also extended. It will be very good. In addition, when the above effect is combined with the effect of each mixing unit 18a to 18p itself having a gentle step, the effect is further increased.

＜第二実施形態＞
次に、第二実施形態について説明する。第二実施形態は、第一実施形態に対して砥石車の研削対象である凹部に対する相対的な大きさが異なるのみである。第一実施形態では、砥石車１０は外周の凹部よりも大きな断面形状を有した総形の研削砥石とした。しかし、第二実施形態では、砥石車１１０は、図７に示すように、凹部内に収容可能な大きさである。なお、砥石車１１０の構成は、第一実施形態の砥石車１０と同様である。よって、同様の構成には、第一実施形態と同様の符号を付して説明する。 <Second embodiment>
Next, a second embodiment will be described. The second embodiment is different from the first embodiment only in the relative size with respect to the recess that is a grinding target of the grinding wheel. In the first embodiment, the grinding wheel 10 is an overall grinding wheel having a larger cross-sectional shape than the outer peripheral recess. However, in the second embodiment, the grinding wheel 110 is sized to be accommodated in the recess as shown in FIG. The configuration of the grinding wheel 110 is the same as that of the grinding wheel 10 of the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and described.

砥石車１１０によって工作物Ｗを研削する場合について説明する。前述したとおり、工作物Ｗはクランクシャフトであり、研削対象はクランクシャフトの凹部である。図７に示すように、砥石車１１０は、軸線方向において、凹部内に収容可能な大きさで形成されている。このため、砥石車１１０は、凹部の軸線方向両側面４６，４７を研削によって除去加工するため、図７に示す矢印Ａｒ１，矢印Ａｒ２の方向にそれぞれ切り込む。つまり、砥石車１１０は、摩耗しにくい第一砥石チップ１１を備えた軸線方向両端部（Ｒ部）で、凹部の両側面４６、４７を除去加工する。そして、両側面４６、４７の除去加工が終了すると、砥石車１１０の外周面が凹部の底面（外周面）に到達し、摩耗し易い第二砥石チップ１２を備えた砥石車１１０の外周面の円筒部（Ｃ部）によって凹部の底面の仕上げ研削加工が行なわれる。上記以外は、すべて第一実施形態と同様である。このような態様によっても、第一実施形態と同様の効果が得られる。   A case where the workpiece W is ground by the grinding wheel 110 will be described. As described above, the workpiece W is a crankshaft, and the object to be ground is a concave portion of the crankshaft. As shown in FIG. 7, the grinding wheel 110 is formed in a size that can be accommodated in the recess in the axial direction. For this reason, the grinding wheel 110 cuts in the directions of the arrows Ar1 and Ar2 shown in FIG. 7 in order to remove the axially opposite side surfaces 46 and 47 of the recess by grinding. That is, the grinding wheel 110 removes both side surfaces 46 and 47 of the recess at both axial ends (R portion) provided with the first grinding wheel tip 11 that is not easily worn. When the removal processing of both side surfaces 46 and 47 is completed, the outer peripheral surface of the grinding wheel 110 reaches the bottom surface (outer peripheral surface) of the recess, and the outer peripheral surface of the grinding wheel 110 provided with the second grinding wheel tip 12 that easily wears. Finish grinding of the bottom surface of the concave portion is performed by the cylindrical portion (C portion). Except for the above, everything is the same as in the first embodiment. Also by such an aspect, the same effect as the first embodiment can be obtained.

なお、上記第一および第二実施形態における砥石車１０の製造方法では、円板状ベース１３（円板状部材）の外周面に、すでに形成された１６個（複数）の各周方向分割砥石チップＡ〜Ｐを配置することにより砥石層１６を形成した。しかし、このような製造方法に限らず、各周方向分割砥石チップＡ〜Ｐを予め形成せず、周方向分割砥石チップＡ〜Ｐを構成する第一及び第二砥石チップ１１，１２を外周面に別々に貼り付けて製造してもよい。この場合、周方向分割砥石チップＡ〜Ｐは、混合部１８ａ〜１８ｐを備えず、幅及び実体を有さない軸線方向境界部のみを備えることとなる。つまり第一砥石チップ１１と第二砥石チップ１２とを混合部１８ａ〜１８ｐを介在させずに隣接させることとなる。これによっても、相応の効果は得られる。   In the method for manufacturing the grinding wheel 10 in the first and second embodiments, 16 (plural) circumferentially divided grindstones already formed on the outer peripheral surface of the disk-shaped base 13 (disk-shaped member). The grindstone layer 16 was formed by disposing the chips A to P. However, not limited to such a manufacturing method, the circumferentially divided grindstone chips A to P are not formed in advance, and the first and second grindstone chips 11 and 12 constituting the circumferentially divided grindstone chips AP are arranged on the outer peripheral surface. It may be manufactured by pasting separately. In this case, the circumferentially divided grindstone tips A to P do not include the mixing portions 18a to 18p, and include only the axial boundary portion having no width and substance. That is, the 1st whetstone chip 11 and the 2nd whetstone chip 12 will be made to adjoin, without interposing mixing parts 18a-18p. This also provides a reasonable effect.

また、各周方向分割砥石チップＡ〜Ｐの混合部１８ａ〜１８ｐを本実施形態とは異なる製造方法で製造してもよい。つまり、混合部１８ａ〜１８ｐを単体でプレスし製造して、第一砥石チップ１１と第二砥石チップ１２との間に介在させてもよい。これによっても上記実施形態と同様の効果が得られる。   Moreover, you may manufacture the mixing parts 18a-18p of each circumferential direction division | segmentation grindstone chip | tip AP by the manufacturing method different from this embodiment. That is, the mixing portions 18a to 18p may be pressed and manufactured as a single unit and interposed between the first grindstone tip 11 and the second grindstone tip 12. This also provides the same effect as the above embodiment.

また、第一および第二実施形態においては、周方向分割砥石チップを周方向に１６個配置したが、これより多くてもよいし、少なくてもよい。   In the first and second embodiments, 16 circumferentially divided grindstone chips are arranged in the circumferential direction, but the number may be more or less than this.

また、第一および第二実施形態においては、図１Ｂに示すように、第一砥石チップ１１と第二砥石チップ１２との間に形成される各混合部１８ａ〜１８ｐ（軸線方向境界部）は、砥石層１６の両端の各Ｒ部の一部に設けられている。しかし、この態様には限らない。各混合部１８ａ〜１８ｐは、各Ｒ部の残りの一部、または円筒部に設けられていてもよい。これによっても相応の効果は得られる。   Moreover, in 1st and 2nd embodiment, as shown to FIG. 1B, each mixing part 18a-18p (axial direction boundary part) formed between the 1st grindstone chip | tip 11 and the 2nd grindstone chip | tip 12 is shown. , Provided on a part of each R portion at both ends of the grindstone layer 16. However, it is not limited to this aspect. Each mixing part 18a-18p may be provided in the remaining part of each R part, or a cylindrical part. This also provides a reasonable effect.

また、第一および第二実施形態においては、１種類の材質で形成された工作物Ｗに対し、研削抵抗の異なる形状部位に応じて２種類の第一，第二砥石チップ１１，１２を組み合わせて砥石車１０，１１０を構成した。しかし、この態様には限らず、複数の種類の材質が継ぎ合わされた工作物に対して、各材質に応じた各砥石チップを組み合わせて砥石車を構成してもよい。これによっても、上記実施形態と同様の効果が得られる。   In the first and second embodiments, two types of first and second grindstone tips 11 and 12 are combined for a workpiece W formed of one type of material in accordance with a shape portion having a different grinding resistance. The grinding wheels 10 and 110 were configured. However, the present invention is not limited thereto, and a grinding wheel may be configured by combining grindstone tips corresponding to the respective materials with respect to a workpiece in which a plurality of types of materials are joined together. Also by this, the same effect as the above embodiment can be obtained.

１０，１１０…砥石車、１１…第一砥石チップ、１２…第二砥石チップ、１３…円板状ベース（円板状部材）、１４，１９…超砥粒（砥粒）、１５…ビトリファイド結合材、１６…砥石層、１８ａ〜１８ｐ…混合部、２０…レジノイド結合材、２５…研削盤、Ａ〜Ｐ…周方向分割砥石チップ、Ｗ・・・工作物。 DESCRIPTION OF SYMBOLS 10,110 ... Grinding wheel, 11 ... First grindstone chip, 12 ... Second grindstone chip, 13 ... Disc base (disc member), 14, 19 ... Superabrasive (abrasive), 15 ... Vitrified bond 16: Grinding wheel layer, 18a to 18p ... Mixing unit, 20 ... Resinoid binder, 25 ... Grinding machine, AP ... Circumferentially divided grinding wheel tip, W ... Workpiece.

Claims (6)

円板状部材と、
前記円板状部材の外周面に配置される砥石層と、
を備える砥石車であって、
前記砥石層は、周方向に分割される複数の周方向分割砥石チップを備え、
前記複数の周方向分割砥石チップのそれぞれは、性状の異なる第一砥石チップ及び第二砥石チップが軸線方向に配列されて形成され、
前記複数の周方向分割砥石チップのそれぞれにおいて前記第一砥石チップと前記第二砥石チップとの境界部は、軸線方向境界部と定義し、
前記複数の周方向分割砥石チップのうち周方向に連続して配置される少なくとも３つの周方向分割砥石チップにおける前記軸線方向境界部は、周方向に連続して配置された前記少なくとも３つの周方向分割砥石チップの順に前記軸線方向の所定の方向に向かって整列している、砥石車。 A disk-shaped member;
A grindstone layer disposed on the outer peripheral surface of the disk-shaped member;
A grinding wheel equipped with
The grindstone layer includes a plurality of circumferentially divided grindstone chips divided in the circumferential direction,
Each of the plurality of circumferentially divided grindstone tips is formed by arranging first and second grindstone tips having different properties in the axial direction,
In each of the plurality of circumferentially divided grindstone tips, a boundary portion between the first grindstone tip and the second grindstone tip is defined as an axial boundary portion,
Among the plurality of circumferentially divided grindstone chips, the axial boundary in at least three circumferentially divided grindstone chips that are continuously arranged in the circumferential direction is the at least three circumferential directions that are continuously arranged in the circumferential direction. A grinding wheel that is aligned in the order of the divided grinding wheel chips in a predetermined direction in the axial direction. 前記第一砥石チップは、砥粒の粒径が大きくて硬度が高く、
前記第二砥石チップは、砥粒の粒径が小さくて硬度が低く、
前記第一砥石チップは、前記砥石層の軸線方向の両端部に配置され、
前記第二砥石チップは、前記砥石層の軸線方向の中央部に配置される、請求項１に記載の砥石車。 The first grindstone tip has a large grain size and high hardness,
The second grindstone tip has a small grain size and low hardness,
The first grindstone tip is disposed at both ends in the axial direction of the grindstone layer,
2. The grinding wheel according to claim 1, wherein the second grinding wheel tip is disposed at a central portion in an axial direction of the grinding wheel layer. 前記砥石層は、円筒部と、前記円筒部の両端に配置される各Ｒ部とを備え、
前記第一砥石チップは、前記各Ｒ部の一部に配置され、
前記第二砥石チップは、前記円筒部及び前記各Ｒ部の残りの一部に配置され、
前記軸線方向境界部は、前記各Ｒ部の一部に配置される、請求項２に記載の砥石車。 The grindstone layer includes a cylindrical portion and R portions disposed at both ends of the cylindrical portion,
The first grindstone tip is disposed in a part of each R portion,
The second grindstone tip is disposed on the remaining part of the cylindrical portion and each R portion,
The grinding wheel according to claim 2, wherein the axial direction boundary portion is disposed at a part of each R portion. 前記各境界部は前記軸線方向に所定の幅を有し、当該所定の幅の中には前記各境界部の前記軸線方向両端に配置された前記性状の異なる前記第一、第二砥石チップの前記各砥粒が混在して混合部を形成する、請求項１〜３の何れか１項に記載の砥石車。   Each of the boundary portions has a predetermined width in the axial direction, and the first and second grindstone chips having different properties disposed at both ends of the boundary portion in the axial direction are included in the predetermined width. The grinding wheel according to claim 1, wherein the abrasive grains are mixed to form a mixing portion. 前記各混合部は前記円板状部材の外周面の前記周方向において隣接する前記混合部との軸線方向におけるオーバーラップ量が変化する、請求項４に記載の砥石車。   5. The grinding wheel according to claim 4, wherein the amount of overlap of each of the mixing portions in the axial direction with the mixing portion adjacent in the circumferential direction of the outer peripheral surface of the disk-shaped member varies. 砥石車の製造方法であって、
前記砥石車は、請求項１〜５の何れか１項に記載の砥石車であり、
前記砥石車の製造方法は、
前記円板状部材の外周面に前記複数の周方向分割砥石チップのそれぞれの前記第一及び第二砥石チップを配置することにより前記砥石層を形成する砥石車の製造方法。 A method of manufacturing a grinding wheel,
The grinding wheel is the grinding wheel according to any one of claims 1 to 5,
The grinding wheel manufacturing method is:
A grinding wheel manufacturing method for forming the grinding wheel layer by disposing the first and second grinding wheel tips of each of the plurality of circumferentially divided grinding stone tips on an outer peripheral surface of the disk-shaped member.

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