JPS62148160A - Inner surface grinding grindstone having super abrasive grain and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent the abrupt deterioration of the grindability accompanied by decrease of the diameter of a grindstone, by constituting such that grinding effect becomes harder gradually from the outer peripheral part thereof to at least the use limitation diameter thereof. CONSTITUTION:A lower pressing die 9 is fitted into a cylindrical outer die 1 while a shaft die 3 is fixed in the central part. Next, a raw material powder body is thrown on the upper surface of the lower pressing die 9 and then the surface is leveled, and the upper pressing die 10 is thereafter fitted on the shaft die 3 while it is pressed so that said powder body is compressed to form a grindstone material 12. Here, inclination is formed on the upper surface of the lower pressing die 9 or the lower surface of the upper pressing die 10 so that the thickness of a grindstone becomes larger toward the outer periphery of the pressing die, whereby the thickness of the grindstone after the compression is finished becomes thicker gradually from the use limitation diameter of a grindstone to the outer peripheral part thereof. Thus, the grindstone has a tendency that hard grinding effect becomes stronger gradually from the grindstone start diameter to the use limitation diameter while maintaining the high grindability from the start so that super abrasive grain inner surface grinding grindstones having good grindability can be obtained.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 この発明は、内面研削加工における超砥粒内面研削砥石
とその製造方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a superabrasive internal grinding wheel for internal grinding and a method for manufacturing the same.

〔従来の技術〕[Conventional technology]

従、来、内面研削加工における研削砥石として、高速回
転する研削砥石の内周部分を高密度、高結合度砥石とし
た補強砥石、たとえば、イ）山水明：補強砥石の設計−
補強の限界と最適補強径、精密機械ＶＯＬ、３Ｂ、ＮＯ
，９（１９７２）４Ｂ、が知られている。Traditionally, reinforced grinding wheels have been used as grinding wheels for internal grinding, in which the inner peripheral part of the grinding wheel rotates at high speed and has a high density and high bonding degree, for example, a) Akira Sansui: Design of reinforced grinding wheels -
Reinforcement limits and optimal reinforcement diameter, precision machinery VOL, 3B, NO
, 9 (1972) 4B, is known.

イ）は回転する砥石の遠心力による内周部からの破壊に
対する安全対策として考えられたものであって、砥石の
研削性能の改善のためのものではない。特に、たとえば
、直径５０ｍ５＋以下の砥石径が小さく質量が小さい内
面研削用小型砥石においては、軽量で遠心力も軽減され
るので、前記補強対策なども考慮されていない。A) was considered as a safety measure against destruction from the inner periphery due to the centrifugal force of the rotating whetstone, and is not intended to improve the grinding performance of the whetstone. In particular, for example, in the case of a small grindstone for internal grinding, which has a small diameter of 50 m 5+ or less and has a small mass, it is lightweight and the centrifugal force is reduced, so the above-mentioned reinforcement measures are not taken into account.

また、内面研削砥石の成形方法として、口）砥石内周部
を密化することを目的とする成形方法が考えられている
。この方法を、第６図および第７図に基づいて説明する
。Furthermore, as a method for forming an internal grinding wheel, a forming method is being considered that aims to make the inner circumference of the grindstone denser. This method will be explained based on FIGS. 6 and 7.

１は円筒状の外型、２はこの外型ｌの内に嵌入されだ円
板状の上押型、３はこの上押型２に下端部を嵌入した軸
型、４はこの軸型３と外型１間のキャビティ、５はこの
キャビティ４に投入される立方晶窒化硼素あるいはダイ
ヤモンドなどの砥粒と結合剤などから成る原料粉体、６
はこの原料粉体５を押圧する円板状の上押型、７はこの
上押型６を上方から押し、原料粉体５をキャビティ４内
に均等に充填する仮押型、８はこの仮押型７によりプレ
ス機（図示せず）を用いて圧縮した砥石素材である。1 is a cylindrical outer mold, 2 is a disc-shaped upper mold that is fitted into this outer mold 1, 3 is a shaft mold whose lower end is fitted into this upper mold 2, and 4 is a shaft mold 3 and the outer mold. A cavity between the molds 1, 5 is a raw material powder made of abrasive grains such as cubic boron nitride or diamond, and a binder, which is introduced into the cavity 4;
7 is a disk-shaped upper press die that presses the raw material powder 5; 7 is a temporary press die that presses this upper press die 6 from above and evenly fills the raw material powder 5 into the cavity 4; 8 is a temporary press die that presses the raw material powder 5; This is a grindstone material compressed using a press machine (not shown).

この方法では、第６図（Ａ）に示すように、外型ｌ内に
上押型２を嵌入し、次に、この上押型２の中央部に軸型
３を起立固定し、上押型２．外型１、軸型３で形成され
るキャビティ４内の上押型２上面に所定量の原料粉体５
を投入して、第６図（Ｂ）に示すように１円板上の上押
型６の上面から矢印方向に仮押型７により、プレス機を
用いて圧縮して、成形後、砥石厚みの均一な砥石素材８
とする。In this method, as shown in FIG. 6(A), an upper press die 2 is fitted into an outer die l, then a shaft die 3 is fixed upright in the center of the upper press die 2, and the upper press die 2. A predetermined amount of raw material powder 5 is placed on the upper surface of the upper press mold 2 in the cavity 4 formed by the outer mold 1 and the shaft mold 3.
As shown in FIG. 6(B), from the upper surface of the upper press die 6 on one disc, the temporary press die 7 is compressed using a press machine in the direction of the arrow, and after forming, the grindstone thickness is uniform. Whetstone material 8
shall be.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

ところが、説明してきたように、イ）は研削砥石、特に
内面研削砥石で砥石径が小さいものでは、回転による遠
心力で砥石内周部からの破壊に対しての安全対策として
はそれなりに有効ではあるが、本願の発明の目的とする
研削性能の改善に直接寄与するものではない。However, as explained above, (a) is not an effective safety measure for grinding wheels, especially internal grinding wheels with a small diameter, as a safety measure against damage from the inner circumference of the wheel due to centrifugal force caused by rotation. However, it does not directly contribute to the improvement of grinding performance, which is the objective of the invention of the present application.

また、従来の口）の方法では、研削作用の低下を防ぐた
め、内周部を密化することを目的としたものであるが、
半径方向での密度差を確実に形成しにくいという難点が
あった。In addition, in the conventional method, the aim is to make the inner periphery denser in order to prevent the deterioration of the grinding effect.
There was a problem in that it was difficult to reliably form a density difference in the radial direction.

この点についてさらに詳細に説明する。砥石回転数を一
定した研削作業において、内面研削砥石は本来、外径は
ワークの加工穴径より小さくなければならない、いま、
砥粒と結合剤などから成る原料粉体の圧縮前の充填厚み
をｈと圧縮後の砥石厚みｈ′の比ｈ’／ｈで、圧縮比を
表わすとすると、半径方向の幅が小さく成形時に圧縮方
向に直角方向での砥粒粉体の移動拡がりにより、目標と
する密度差が得られず、特に高圧縮力で圧縮比の小さい
砥石の成形ではこの傾向は大きくなってしまう。This point will be explained in more detail. In grinding work where the speed of the grinding wheel is constant, the outer diameter of the internal grinding wheel must be smaller than the diameter of the hole to be machined in the workpiece.
If we express the compression ratio by the ratio h'/h of the filling thickness of the raw material powder consisting of abrasive grains and binder before compression to h and the thickness of the grinding wheel after compression h', then the width in the radial direction is small and the Due to the movement and spread of the abrasive grain powder in the direction perpendicular to the compression direction, the target density difference cannot be obtained, and this tendency becomes particularly large when forming a grindstone with high compression force and small compression ratio.

才だ、内面研削砥石、特に小径の砥石では、外径の減少
に伴なう砥石の表面速度の低下は゛顕著であり、それに
伴なって単位時間当りの砥粒作動刃数は減少し、研削性
の低下、砥石形状崩れなどによる仕上面あらさ、加工精
度などの砥石性能が悪化するとともに、ドレッシング間
加工出来高が急減するという問題点があった。For internal grinding wheels, especially small-diameter ones, the decrease in the surface speed of the grinding wheel as the outer diameter decreases is remarkable, and the number of abrasive blades operating per unit time decreases accordingly, making the grinding process faster. There were problems in that the performance of the grinding wheel, such as reduced surface roughness, processing accuracy, etc., deteriorated due to the deterioration of the grinding wheel's shape, and the processing yield during dressing decreased sharply.

〔問題点を解決するための手段〕　　、本願の第１の発
明と第２の発明は、それぞれさきに、イ）９口）につい
て説明したような問題点を解決するためになされたもの
で、本願の第１の発明（以下第１の発明という。）は、
研削作用相当部分が立方晶窒化硼素あるいはダイヤモン
ドなどから成る研削砥石において、砥石外周部から少な
くとも砥石使用限界径に至るにしたがって砥石組織を密
化して、研削作用として硬目作用とすることによって、
一定の回転数で、砥石スタート径から使用限界径にわた
って高研削性能を維持し、所要の仕上面粗さ・加工精度
が得られ、研削作用相当部分が大きく、かつ、ドレッシ
ング間加工出来高の減少の低減など研削性能が良い超砥
粒内面研削砥石を提供することをその目的とするもので
ある。　、 また、本願の第２の発明（以下第２の発明という。）は
、砥石成形時において、砥石素材と接する圧縮面に傾斜
状部を有する押型により、抑圧方向に直角方向での圧縮
比を、砥石外周部で最も大きく砥石使用限界径で最も小
さくなるように、成形後の砥石厚みを砥石外周部で最も
厚く砥石使用・限界径で最も薄くしたことにより、圧縮
比が傾向的に変化した砥石組織を有するとともに、研削
性能が良い超砥粒内面研削砥石の製造方法を提案するも
のである。[Means for solving the problem] The first invention and the second invention of the present application have been made in order to solve the problems as explained above in regard to (a) 9), respectively, The first invention of the present application (hereinafter referred to as the first invention) is:
In a grinding wheel whose portion corresponding to the grinding action is made of cubic boron nitride or diamond, the structure of the grinding wheel is made denser from the outer periphery of the wheel to at least the limit diameter for use of the grinder, and the grinding action is made to have a hard grain action.
At a constant rotation speed, high grinding performance is maintained from the starting diameter of the grinding wheel to the working limit diameter, the required finished surface roughness and machining accuracy are obtained, the equivalent part of the grinding action is large, and the processing output during dressing is reduced. The purpose is to provide a super-abrasive internal grinding wheel that has good grinding performance such as reduction in grinding performance. In addition, the second invention of the present application (hereinafter referred to as the second invention) is to increase the compression ratio in the direction perpendicular to the suppression direction by using a pressing die having an inclined portion on the compression surface that contacts the grindstone material during grindstone forming. , the compression ratio changed in a trend by making the thickness of the grinding wheel after forming thickest at the outer periphery of the whetstone and thinnest at the limit diameter for use of the whetstone, so that it was largest at the outer periphery of the whetstone and smallest at the limit diameter for use of the whetstone. This paper proposes a method for manufacturing a superabrasive internal grinding wheel that has a grinding wheel structure and has good grinding performance.

〔作用〕[Effect]

第１の発明の超砥粒内面研削砥石は、研削作用相当部分
が立方晶窒化硼素あるいはダイヤモンドなどから成る研
削砥石において、砥石外周部から少なくとも砥石使用限
界径に至るにしたがって砥石組織を密化して、研削作用
として硬ＩＩ作用としたので、砥石径の減少に伴なう急
激な研削性の劣化を防止して高研削性を維持し、かつ、
研削作用相当部分の砥石層が増大される。The super-abrasive internal grinding wheel of the first invention is a grinding wheel in which the portion corresponding to the grinding action is made of cubic boron nitride or diamond, and the grinding wheel structure is made denser from the outer periphery of the wheel to at least the limit diameter for use of the grinder. , Since the grinding action is hard II action, rapid deterioration of grinding performance due to a decrease in the diameter of the grinding wheel is prevented and high grindability is maintained, and
The grindstone layer in the portion corresponding to the grinding action is increased.

また、第２の発明の超砥粒内面研削砥石の製造方法によ
れば、砥石成形時において、砥石素材と接する圧縮面に
傾斜状部を有する押型により、圧縮成形後の砥石で、少
なくとも砥石使用限界径から砥石外周部に向って傾斜状
に砥石厚みを厚くし、砥粒と結合剤などからなる原料粉
体の圧縮前の充填後高さで圧縮後の砥石厚みを除した圧
縮比が砥石外周部で最も大きく、砥石使用限界径で最も
小さくなるように成形されるので、半径によって圧縮比
の異なる砥石組織が得られ砥石スタート径から少なくと
も砥石使用限界径に至るにしたがって傾向的に硬目研削
作用を有し、研削初めの高研削性を維持して研削性能が
良い超砥粒内面研削砥石が製造される。Further, according to the method for manufacturing a super-abrasive internal grinding wheel of the second invention, at the time of forming the grindstone, at least the use of the grindstone is performed by using a pressing mold having an inclined portion on the compression surface that contacts the grindstone material, so that the grindstone can be used after compression molding. The thickness of the grinding wheel is increased in a slope from the limit diameter toward the outer periphery of the grinding wheel, and the compression ratio of the grinding wheel is calculated by dividing the thickness of the grinding wheel after compression by the height after filling the raw material powder consisting of abrasive grains and binder before compression. Since it is formed so that it is largest at the outer periphery and smallest at the limit diameter of the grindstone, a grindstone structure with a compression ratio that differs depending on the radius is obtained, and the grindstone tends to become harder from the starting diameter of the grindstone to at least the limit diameter of the grindstone. A superabrasive internal grinding wheel that has a grinding action, maintains the high grindability at the beginning of grinding, and has good grinding performance is manufactured.

〔実施例〕〔Example〕

以下にこの発明の一実施例を、第１図ないし第５図を用
いて説明する。An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

符号１〜８は、従来の砥石の成形方法と同一部分または
相当部分を示し、説明の詳細は重複をさけ省く、９は円
筒状の上押型、１０はこの上押型９上のキャビティ４に
装填した立方晶窒化硼素の砥粒と結合剤を主体とする原
料粉体５を押圧して成形する円筒状の上押型、１１はこ
の−Ｌ押型１０と上押型９の圧縮面に設けた傾斜状部、
ｔはこの傾斜状部１１の段差、１２はこの段差ｔがある
傾斜状部１１を設けた上押型９、上押型１０のうち、少
なくとも何れかを用いて成形した砥石素材、１３はこの
砥石素材１２を仕上げた砥石、ａは上記砥石素材８．１
２からつくった砥石の外周部径、ｂは同砥石使用限界径
、αは同研削作用相当部分、βは同非研削作用部分であ
る。Reference numerals 1 to 8 indicate the same parts or equivalent parts as in the conventional grindstone forming method, and the details of the explanation will be omitted to avoid duplication. 9 is a cylindrical upper mold, and 10 is loaded into the cavity 4 on this upper mold 9. A cylindrical upper die 11 is formed by pressing the raw material powder 5 mainly composed of cubic boron nitride abrasive grains and a binder, and 11 is an inclined shape provided on the compression surface of the -L die 10 and the upper die 9. Department,
t is the step of the inclined portion 11, 12 is the grindstone material formed using at least one of the upper mold 9 and the upper mold 10 provided with the inclined portion 11 having the step t, and 13 is the grindstone material. 12 is the finished whetstone, a is the above whetstone material 8.1
b is the diameter of the outer periphery of the grindstone made from No. 2, b is the limit diameter for use of the grindstone, α is the portion corresponding to the grinding action, and β is the portion corresponding to the non-grinding action.

超砥粒内面研削砥石をつくるには、まず、円筒状の外型
１の内部に円板状の上押型２または９を嵌入し、その中
央部に軸型３を起立固定する０次いで、上押型９上面に
所定量の原料粉体５を投入して該粉体表面を水平になら
した後、上方より円板状の上押型ｌＯを軸型３に嵌装し
、さらに、上押型１０上面から矢印方向に仮押型７によ
りプレス機を用いて圧縮後、砥石素材１２をうる。To make a superabrasive internal grinding wheel, first, a disc-shaped upper mold 2 or 9 is fitted inside a cylindrical outer mold 1, and a shaft mold 3 is fixed upright in the center of the upper mold 2 or 9. After putting a predetermined amount of raw material powder 5 on the upper surface of the pressing mold 9 and leveling the powder surface, a disc-shaped upper pressing mold 10 is fitted into the shaft mold 3 from above, and then the top surface of the upper pressing mold 10 is A grindstone material 12 is obtained after compression using a press machine using a temporary pressing die 7 in the direction of the arrow.

砥石素材１２と接する上押型９の上面、あるいは上押型
ｌＯの下面に、砥石素材１２の外周で砥石厚みが大きく
なるように押型外周部に傾斜を形成させることにより、
圧縮後の砥石厚みは、砥石使用限界径から砥石外周部に
向って、厚くなり、［１標の圧縮比になるよう所定の深
さまで仮押型７を押し込むことにより、抑圧方向に直角
な方向（砥石半径方向）での圧縮比が砥石半径で異なる
砥石素材１２をうる。By forming a slope on the outer periphery of the press die on the upper surface of the upper press die 9 in contact with the grindstone material 12 or on the lower surface of the upper press die lO so that the thickness of the grindstone increases at the outer periphery of the grindstone material 12,
The thickness of the whetstone after compression becomes thicker from the limit diameter of the whetstone toward the outer periphery of the whetstone. To obtain a grindstone material 12 whose compression ratio in the grindstone radial direction differs depending on the radius of the grindstone.

なお、砥石素材１２は圧縮後、砥石厚み中央部に中ｑ面
が生じ、密度分布はこれを中心に上下対称になるよう両
押し法などによる。Note that after the grinding wheel material 12 is compressed, a middle q plane is generated at the center of the thickness of the grinding wheel, and the density distribution is made vertically symmetrical with respect to this by a double pressing method or the like.

このように成形した砥石素材１２を乾燥後、焼成する。The grindstone material 12 formed in this manner is dried and then fired.

砥石素材１２の圧縮後における厚み不同は、乾燥後ある
いは焼成後に平面仕上を行って均一な砥石厚みとする。The uneven thickness of the grindstone material 12 after compression is resolved by flattening it after drying or firing to make the grindstone thickness uniform.

たとえば、砥石の外周部径が約２５ｍｍ、厚みが約ｓｍ
ｍの超砥粒内面研削砥石の圧縮成形では、砥石使用限界
径すの部分の圧縮比を、砥石の外周部径ａの部分の圧縮
比に対して、たとえば約３％から１０％の範囲で小さく
すると、適当に緻密な砥石組織となり、この圧縮比の減
少比率％は、成形後の砥石使用限界径すの部分の厚さが
、砥石の外周部の厚さに対して、約０．２ｍ厘から０．
８ｓｍの範囲で小さいことに相当する。For example, the outer diameter of the grindstone is about 25 mm, and the thickness is about sm.
In the compression molding of a super-abrasive internal grinding wheel of m, the compression ratio of the grindstone's usable limit diameter part is set in the range of, for example, about 3% to 10% of the compression ratio of the part of the outer circumferential diameter of the grindstone. If it is made smaller, the grinding wheel structure becomes suitably dense, and the reduction ratio of this compression ratio (%) means that the thickness of the grinding wheel use limit diameter after forming is approximately 0.2 m relative to the thickness of the outer circumference of the grinding wheel. 0.
This corresponds to being small within the range of 8sm.

したがって、上押型９．上押型１０の傾斜形状部１１の
段差ｔが約０．１ｍｍから０．３■鵬の範囲で製作され
ることが好ましい、何故ならば、第１図（Ａ）に示すよ
うな型押し法において段差ｔが０゜１ｍｍ以下では、砥
粒密度に大きさ差がみられず効果が小ざくなるからであ
る。また、第１図（Ｂ）に示すような両押し法において
、段差ｔが０．３ａ＋ｍ以上では、成形後の砥石厚みの
差が０Ｊｔａｔｓ以りと大きくなり、たとえば圧縮力の
小さい場合、圧縮方向に直角な方向での原料粉体５の移
動拡がりの不足により砥石外周部が軟かく粗となるなど
の結果を生じるためである。Therefore, the upper press mold 9. It is preferable that the step t of the inclined portion 11 of the upper stamping die 10 is manufactured within the range of about 0.1 mm to 0.3 mm, because in the stamping method as shown in FIG. 1(A), This is because when the step difference t is 0°1 mm or less, there is no difference in the size of the abrasive grain density, and the effect becomes small. In addition, in the double pressing method as shown in Fig. 1(B), if the step t is 0.3a+m or more, the difference in the thickness of the grinding wheel after forming becomes larger than 0Jtats.For example, if the compression force is small, the compression direction This is because the outer periphery of the grindstone becomes soft and rough due to insufficient movement and spread of the raw material powder 5 in the direction perpendicular to the grinding wheel.

しかして、ＣＢＮ研削砥石の外周部から使用限異径まで
の長さく半径方向の幅）が小さいときは、特に高圧縮力
で原料粉体の圧縮方向に直角な方向での拡がりを増し全
体が同一組織となってしまうため、少なくとも研削砥石
の半径方向の幅（ａからｂ）は、たとえば３ＩＩＩＩＢ
以上が望ましく約５ｆｆｉＩＩｌ付近が適量である。こ
の砥石の外周部径ａから砥石使用限界径すまでの間が研
削に用いる研削作用相当部分αで砥石使用限界径すより
も内側は非研削作用部分βである。However, when the length and radial width from the outer periphery of the CBN grinding wheel to the usable limit diameter is small, especially when the compression force is high, the raw material powder spreads in the direction perpendicular to the compression direction, increasing the overall Since the structure is the same, at least the radial width (a to b) of the grinding wheel is, for example, 3IIIB.
The amount above is desirable, and the appropriate amount is around 5ffiIIIl. The area between the outer peripheral diameter a of the grindstone and the limit diameter for use of the grindstone is a grinding action portion α used for grinding, and the area inside the limit use diameter of the grindstone is a non-grinding action portion β.

つぎに、第１の発明による試験砥石について従来法によ
る比較砥石と対比して説明する。Next, the test whetstone according to the first invention will be explained in comparison with a comparative whetstone according to the conventional method.

試験砥石と比較砥石の成形に当って、砥粒と結合剤を主
体とする原料粉体の組成は同一とする。When forming the test whetstone and the comparison whetstone, the composition of the raw material powder, which mainly consists of abrasive grains and a binder, is the same.

すなわち、砥粒は米国Ｇ、Ｅ社のＣＢＮＩタイプ２３０
／２７０メツシュを使用し、結合剤は特公昭５７−４９
３５１号公報に記載のものに準じたビトリファイドボン
ドを適用し、また、金型材質は一般構造用圧延鋼材また
は機械構造用炭素鋼々材とする。In other words, the abrasive grains are CBNI type 230 manufactured by G and E companies in the United States.
/270 mesh is used, and the binder is Special Publication No. 57-49.
A vitrified bond similar to that described in Publication No. 351 is used, and the mold material is rolled steel for general structures or carbon steel for machine structures.

比較砥石である従来法による成形品は、たとえば第６図
（Ｂ）に示す上、上押型２．６のように砥石素材と接す
る圧縮面の形状が水平である押型を使用して、混合調整
された原料粉体５を外径２６ｍｍ、内径６ｍｍの押型の
キャビティ４内に均等に充Ｉ最した後、成形後の生砥石
の厚みが５．８ｍｍとなるように圧縮比０．６を定めて
押圧し、砥石内径から外径に至る間、抑圧方向に直角な
半径方向での圧縮比は０．６で同一の圧粉密度とする。The comparative grindstone, a molded product made by the conventional method, is mixed and adjusted by using a press die whose compressed surface in contact with the grindstone material is horizontal, such as the upper press die 2.6 shown in FIG. 6(B). After uniformly filling the raw material powder 5 into the cavity 4 of a mold with an outer diameter of 26 mm and an inner diameter of 6 mm, a compression ratio of 0.6 was determined so that the thickness of the green grindstone after molding would be 5.8 mm. The compression ratio in the radial direction perpendicular to the suppression direction is 0.6 and the green density is the same from the inner diameter to the outer diameter of the grindstone.

試験砥石の成形には第（１）図（Ｂ）に示す砥石素材１
２と接する圧縮面において傾斜状部１１を有する上押型
９と上押型１０とを用い、押型形状は外径２６■、内径
６＋ｗｍの円板状で、使用限界直径１４．５ａ＋ｍとし
、第２図に示す傾斜状部１１の段差ｔは０．１５鵬ｍと
する。To form the test whetstone, use the whetstone material 1 shown in Figure (1) (B).
The upper pressing die 9 and the upper pressing die 10 having an inclined part 11 on the compression surface in contact with 2 are used, and the pressing die shape is a disk shape with an outer diameter of 26 cm and an inner diameter of 6+wm, and the usable limit diameter is 14.5a+m, as shown in FIG. The level difference t of the inclined portion 11 shown in is 0.15 m.

そして前記比較砥石と同じ〈原料粉体５を押型キャビテ
ィ内に均等に充填した後、砥石外周部に゛おいて成形後
の生砥石の厚みが８．１層層となるよう圧縮比０．６を
定めて押圧する。すなわち、砥石使用限界径では、成形
後の砥石厚みが５．８■層となり圧縮比０．５７で圧粉
密度を増す。The same as the comparative grindstone (after filling the raw material powder 5 evenly into the mold cavity, the compression ratio is 0.6 so that the thickness of the raw grindstone after forming becomes 8.1 layers at the outer periphery of the grindstone). Determine and press. That is, at the grindstone use limit diameter, the thickness of the grindstone after forming becomes 5.8 layers, and the compaction density increases with a compression ratio of 0.57.

したがって、第２の発明の成形方法によると。Therefore, according to the molding method of the second invention.

砥石外周部での圧縮比０．６の最大値から砥石使用限界
径０．５８の最小値に至る間、砥石直径の減少に伴なっ
て圧縮比は確実に比例的に減少し砥石組織を、密化傾向
とし、傾向的に硬目研削作用とすることが可能である。From the maximum compression ratio of 0.6 at the outer periphery of the grinding wheel to the minimum value of 0.58, which is the limit diameter for use of the grinding wheel, the compression ratio decreases steadily and proportionally as the grinding wheel diameter decreases, changing the structure of the grinding wheel. It is possible to make it tend to become denser and to make it tend to have a hard grinding action.

次いで、比較砥石及びこの第１の発明による試験砥石を
乾燥後、最高温度１２３０℃で所要時間４２時間を要し
て焼成完了後、砥石外径２５ａｍ、内径６ｍＩｎ、厚み
５．６Ｈに整形仕上し、さらに、外周面に半径３．７ｍ
ｍの凸曲面形状に仕上げ加工する。Next, the comparison whetstone and the test whetstone according to the first invention were dried and fired at a maximum temperature of 1230° C. for 42 hours, and then shaped and finished to have an outer diameter of 25 am, an inner diameter of 6 mIn, and a thickness of 5.6 H. , and a radius of 3.7m on the outer circumferential surface.
Finish processing into a convex curved shape of m.

仕上げ後の砥石両側面についてロックウェル硬度計を使
用して、圧子に１．５８ａ＋ｍ　（１／１８インチ）鋼
球を用い試験荷重８０ｋｇでダイヤル目盛（赤）の指示
数値による砥石結合度の測定結果は、比較砥石の結合度
数値が９０から９４であるのに対し、試験砥石は砥石外
周部から使用限界径になるのにしたがって硬い傾向が認
められたが、数値そのものは９１から８５の範囲にあり
両砥石間の結合度に大差はなかった。Results of measuring the bonding degree of the grinding wheel using a Rockwell hardness tester on both sides of the grinding wheel after finishing, using a 1.58a+m (1/18 inch) steel ball as an indenter, and using a test load of 80 kg based on the indicated value on the dial scale (red). The bonding degree values of the comparative whetstones ranged from 90 to 94, while the test whetstones tended to become harder from the outer periphery to the usable limit diameter, but the values themselves ranged from 91 to 85. There was no significant difference in the degree of bond between the two grinding wheels.

第４図に示す砥石形状を有する比較量及び本発明による
試験品を使用して凹曲面形状を有する玉軸受の外輪軌道
面のプランジカット研削を行なう、この実験では、所要
の研削面粗さあるいは加工精度などが満足されない時期
をもって砥石表面の再生ドレッシングを行ない、ドレッ
シング間の加工出来高は、砥石直径が小さくなるにした
がって減少してゆくが、比較砥石では砥石径２５ｍｍに
おける研削初めでのドレッシング間加工出来高は。In this experiment, plunge cut grinding of the outer ring raceway surface of a ball bearing having a concave curved surface shape was performed using a comparative amount having the grindstone shape shown in FIG. 4 and a test product according to the present invention. Regeneration dressing of the grinding wheel surface is performed at the time when the processing accuracy is not satisfied, and the processing output between dressings decreases as the grinding wheel diameter becomes smaller, but with the comparison grinding wheel, the processing output between dressings at the beginning of grinding with a grinding wheel diameter of 25 mm is What is the volume?

（砥石使用量が直径３ＩＩＩＩ消耗した時点で）約１／
２に減少低下した。試験砥石では、（砥石使用量が直径
で２倍の８ｍｍ減少した時点でも）ドレッシング間加工
数は約２／３　＜５減少したのみであった。このことは
砥石の一定回転数の下で、砥石直径が減少して砥石使用
限界径に近づくと傾向的に硬ｌ」研削作用となるように
、圧縮比が砥石使用限界径に近づくにつれ小さくなるよ
うにつくられた効果として理解される。(When the amount of grindstone used is 3III in diameter) Approximately 1/
It decreased to 2. With the test grindstone, the number of machining operations between dressings was reduced by only about 2/3 <5 (even when the amount of grindstone used was reduced by 8 mm, which is twice the diameter). This means that under a constant rotation speed of the grinding wheel, as the diameter of the grinding wheel decreases and approaches the limit diameter for use of the grindstone, the grinding action tends to be hard.As the compression ratio approaches the limit diameter for use of the grindstone, the compression ratio decreases. It can be understood as an effect created in this way.

以上に説明したように、第１の発明の超砥粒内面研削砥
石は、一定の回転数の下で、砥石スタート径から使用限
界径すにわたって高研削作用を維持し、かつ研削作用相
当部分αを増大し、所要の什」−面あらさ・加工精度が
得られ、砥石径が小さくなることによるドレッシング間
加工出来高の減少が小さいなど研削性能が良い。As explained above, the superabrasive internal grinding wheel of the first invention maintains a high grinding action from the starting diameter of the grinding wheel to the usable limit diameter under a constant rotation speed, and has a grinding action equivalent portion α The grinding performance is good, with the required surface roughness and machining accuracy being increased, and the reduction in machining output during dressing due to the smaller diameter of the grinding wheel being small.

また、第２の発明の超砥粒内面研削砥石の製造方法によ
ると、圧縮比を砥石外周部から砥石使用限界径にわたっ
て、傾向的に変化した硬目研削作ｊｌｌの砥石組織を有
する超砥粒内面研削砥石を製造でき、砥石直径の減少に
伴なうドレッシング間加工出来高の急減を改善し、安定
した研削性能の持続が容易であるため、砥石の使用限界
直径をより小さくすることができ、内面研削加工でのＣ
ＢＮ研削砥石の実用化拡大への貢献は多大なものがある
。Further, according to the method for manufacturing a super-abrasive internal grinding wheel of the second invention, the super-abrasive grain has a grinding wheel structure with a hard grinding operation in which the compression ratio tends to change from the outer periphery of the grinding wheel to the limit diameter of the grinding wheel. It is possible to manufacture internal grinding wheels, improve the rapid decrease in processing output during dressing due to a decrease in the diameter of the grinding wheel, and easily maintain stable grinding performance, making it possible to further reduce the usable diameter of the grinding wheel. C in internal grinding
The contribution to the expansion of practical use of BN grinding wheels has been significant.

第２の発明の実施例では、傾斜状部を有する押型として
第２図に示すものを用いたが、これに限定されることな
く使用する原料粉体、砥石径などによって他の形状の押
型を用いても同様な作用。In the embodiment of the second invention, the mold shown in FIG. 2 having an inclined portion was used, but the mold is not limited to this, and other shapes may be used depending on the raw material powder used, the diameter of the grindstone, etc. Same effect when used.

効果を奏しうる。It can be effective.

前記の一実施例では、本願の発す１の好適実施例と思わ
れるものを説明したが、この一実施例に限定されるもの
でなく、たとえば砥粒にダイヤモンドを用いるなど種々
の態様が可能であり、また。In the above embodiment, what is considered to be the preferred embodiment 1 of the present application has been described, but it is not limited to this one embodiment, and various embodiments are possible, such as using diamond as the abrasive grain. Yes, again.

第一の発明の超砥粒内面研削砥石を、第２の発明の超砥
粒内面研削砥石の製造方法によって作ったが、この方法
に限らず他の方法で作っても良いことはいうまでもない
。Although the superabrasive internal grinding wheel of the first invention was made by the method of manufacturing the superabrasive internal grinding wheel of the second invention, it goes without saying that it is not limited to this method and may be made by other methods. do not have.

〔発明の効果〕〔Effect of the invention〕

これまで説明してきたように、第１の発明の超砥粒内面
研削砥石は、研削作用相当部分が立方晶窒化硼素あるい
はダイヤモンドなどから成る研削砥石において、砥石外
周部から少なくとも砥石使用限界径に至るにしたがって
、傾向的に硬目研削作用としたことにより、砥石スター
１１から砥石使用限界径にわたって高研削性を維持し、
研削作用相当部分を増大し、所要の仕上面粗さ・加工精
度が得られ、かつ、ドレッシング間加工出来高の減少の
低減など研削性能を向上することができた。As explained above, the superabrasive internal grinding wheel of the first invention is a grinding wheel in which the portion corresponding to the grinding action is made of cubic boron nitride, diamond, etc., from the outer periphery of the grinding wheel to at least the limit diameter for use of the grinding wheel. Accordingly, by making the grinding action tend to be hard, high grindability is maintained from the grindstone star 11 to the limit diameter for use of the grindstone,
By increasing the area equivalent to the grinding action, the required finished surface roughness and machining accuracy were obtained, and the grinding performance was improved, such as by reducing the decrease in machining output during dressing.

さらに、第２の発明の超砥粒内面研削砥石の製造方法に
よれば、砥石素材と接する圧縮面に傾斜形状部を有する
押型を使用することにより、圧縮後砥石の厚みが異なる
成形体とすることによって圧縮比が傾向的に変化した砥
石組織を有し、研削性能が良い超砥粒内面研削砥石を製
造することができた。Furthermore, according to the method for manufacturing a super-abrasive internal grinding wheel of the second invention, by using a pressing mold having an inclined portion on the compression surface that contacts the grinding wheel material, a molded body having different thicknesses of the grinding wheel after compression is obtained. As a result, we were able to produce a superabrasive internal grinding wheel with a grinding wheel structure in which the compression ratio tended to change, and with good grinding performance.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は、本願の発明の製造方法の説明図。 （Ａ）は傾斜状部を有する押型を片側に用いた片押し法
の場合の断面図、（Ｂ）は傾斜状部を有する押型を両側
に用いた両押し法の場合の断面図。 第２図は同傾斜状部を有する上押型の斜視図、第３図は
同圧縮後の砥石形状を示す斜視断面図、第４図は同仕上
後の砥石形状を示す斜視断面図、第５図はこの発明の砥
石断面図、第６図は従来の成形方法の説明図、（Ａ）は
圧縮前の原料粉体の充Ｊｋｉ状ｙＥを示す断面図、（Ｂ
）は圧縮後の成形を示す断面図、第７図は従来品の砥石
断面図である。 １　　：　外型 ３　　：　軸型 ９　　：　上押型 １０　：　上押型 ｌｌ　：　傾斜状部 １２　：　砥石素材 ａ　　：　外周部径 ｂ　　：　砥石使用限界径 α　　：　研削作用相当部分 ｔ　　　：　段差 各図中、同一符号は同一部分または相当部分を示す。FIG. 1 is an explanatory diagram of the manufacturing method of the invention of the present application. (A) is a sectional view in the case of a single-pressing method in which a pressing die having an inclined portion is used on one side, and (B) is a sectional view in the case of a double-pressing method in which a pressing die having an inclined portion is used on both sides. Fig. 2 is a perspective view of the upper pressing die having the inclined portion, Fig. 3 is a perspective sectional view showing the shape of the grinding wheel after compression, Fig. 4 is a perspective sectional view showing the shape of the grinding wheel after finishing, and Fig. 5 The figure is a sectional view of the grinding wheel of the present invention, FIG. 6 is an explanatory diagram of the conventional forming method, (A) is a sectional view showing the filling Jki shape yE of the raw material powder before compression, and (B
) is a sectional view showing forming after compression, and FIG. 7 is a sectional view of a conventional grindstone. 1: Outer mold 3: Shaft mold 9: Upper mold 10: Upper mold ll: Inclined part 12: Grinding wheel material a: Outer diameter b: Grinding wheel usage limit diameter α: Grinding action equivalent portion t: Steps Same in each figure Symbols indicate the same or equivalent parts.

Claims (1)

【特許請求の範囲】 １）研削作用相当部分が立方晶窒化硼素あるいはダイヤ
モンドなどからなる研削砥石において、砥石外周部から
少なくとも砥石使用限界径に至るにしたがって、傾向的
に硬目研削作用としたことを特徴とする超砥粒内面研削
砥石。 ２）前記研削作用相当部分に関して、砥石成形時におい
て、砥石素材と接する圧縮面に傾斜状部を有する押型に
より、押圧方向に直角方向での圧縮比が、砥石外周部で
最も大きく、砥石使用限界径で最も小さくなるように、
成形後の砥石厚みを砥石外周部で最も厚く砥石使用限界
径で最も薄くしたことを特徴とする超砥粒内面研削砥石
の製造方法。[Scope of Claims] 1) In a grinding wheel whose portion corresponding to the grinding action is made of cubic boron nitride, diamond, etc., the hard grinding action tends to occur from the outer periphery of the grinding wheel to at least the limit diameter for use of the grinding wheel. A super-abrasive internal grinding wheel featuring: 2) Regarding the part corresponding to the grinding action, when forming the grindstone, the compression ratio in the direction perpendicular to the pressing direction is the highest at the outer periphery of the grindstone, due to the press mold having an inclined part on the compression surface that contacts the grindstone material, and this is the limit of the use of the grindstone. so that it is the smallest in diameter,
A method for manufacturing a super-abrasive internal grinding wheel, characterized in that the thickness of the wheel after forming is the thickest at the outer periphery of the wheel and the thinnest at the limit diameter for use of the wheel.