JP4189095B2

JP4189095B2 - Camshaft polishing equipment

Info

Publication number: JP4189095B2
Application number: JP25850899A
Authority: JP
Inventors: 久儀吉野
Original assignee: ヤマハマリン株式会社
Priority date: 1999-09-13
Filing date: 1999-09-13
Publication date: 2008-12-03
Anticipated expiration: 2019-09-13
Also published as: JP2001079745A

Description

【０００１】
【発明の属する技術分野】
本発明は、エンジンのカム軸のカムを砥石によって研磨するカム軸用研磨装置に関するものである。
【０００２】
【従来の技術】
従来、この種のカム軸用研磨装置は、カム軸の両端部を保持し、低速で回転するカム軸のカムに高速で回転する砥石を押付ける構造を採っている。砥石は１本のカム軸に対して１個使用し、基準になるカムプロフィールに倣ってカムに対して進退させている。また、この研磨装置は、砥石の押圧力でカム軸が撓むのを阻止する荷重受け部材を備えている。この荷重受け部材は、カム軸の軸線方向から見て砥石と対称の位置であって、研磨するカムの両側の軸部分に添接するように配置している。
【０００３】
【発明が解決しようとする課題】
上述したように構成した従来のカム軸用研磨装置においては、１個の砥石で全てのカムを順次研磨する構造であり、生産性を向上させるには限界があった。このような不具合は、砥石の数量を増大させることによって解消することができる。しかしながら、砥石が増加する分だけ荷重受け部材の数も増大させなければならず、研磨装置の構造が複雑になってしまう。
【０００４】
本発明はこのような問題点を解消するためになされたもので、荷重受け部材の増加により構造が複雑になるのを阻止しながら、生産性が向上するカム軸用研磨装置を提供することを目的とする。
【０００５】
【課題を解決するための手段】
この目的を達成するため、本発明に係るカム軸用研磨装置は、カム軸の両端部を保持し、このカム軸の吸気弁用カムと排気弁用カムとに砥石を回転させて押付けるカム軸用研磨装置において、カム軸の径方向の一方から吸気弁用カムに押付けられる砥石を有する第１の研磨ユニットと、カム軸の径方向の他方から排気弁用カムに押付けられる砥石を有する第２の研磨ユニットと、カム軸の軸線方向において排気弁用カムを挟んで第１の研磨ユニットの砥石とは反対側に配置され、第１の研磨ユニットの砥石と同方向からカム軸に添接する第１の荷重受け部材と、カム軸の軸線方向において吸気弁用カムを挟んで第２の研磨ユニットの砥石とは反対側に配置され、第２の研磨ユニットの砥石と同方向からカム軸に添接する第２の荷重受け部材とを備えているものである。
本発明によれば、一方の砥石をカムに押付ける力を他方の砥石と荷重受け部材とによって受けることができる。すなわち、二つの砥石を吸気弁用カムと排気弁用カムとにそれぞれ押付けたときにカム軸に生じる回転モーメントを相殺することができる。
また、本発明によれば、同一の気筒の吸気弁と排気弁を駆動する吸気弁用カムと排気弁用カムを一方の砥石と他方の砥石とで研磨することによって、二つの砥石を軸線方向に近接させることができる。このため、一方の砥石の押圧力を受ける他方の砥石と荷重受け部材との間隔を狭めることができ、カム軸が撓むのを確実に阻止することができる。
【０００７】
【発明の実施の形態】
以下、本発明に係るカム軸用研磨装置の一実施の形態を図１ないし図３によって詳細に説明する。図１は本発明に係るカム軸用研磨装置の概略構成を示す平面図、図２はカム軸と砥石を拡大して示す平面図、図３は砥石と荷重受け部材の側面図で、同図は図２におけるIII−III線断面図である。
これらの図において、符号１で示すものは、この実施の形態によるカム軸用研磨装置である。この研磨装置１は、３気筒エンジンに使用するカム軸２を研磨するためのもので、カム軸２の両端部を支持して低速で回転させるカム軸駆動ユニット３と、基準になるカム軸４を有するカム形状検出用ユニット５と、このカム形状検出用ユニット５が検出したカムプロフィールに倣って前記カム軸２の吸気弁用カム６、排気弁用カム７を研磨する第１の研磨ユニット８および第２の研磨ユニット９と、荷重受け部材１０（図２および図３参照）とを備えている。
【０００８】
前記カム軸駆動ユニット３は、カム軸２の両端部をそれぞれチャック１１，１２で保持し、図１において左側に位置するチャック１１に接続したモータ（図示せず）によってカム軸２を低速で回転させる構造を採っている。
カム形状検出用ユニット５は、研磨対象の前記カム軸２とは別の基準カム軸４を低速で回転させ、この基準カム軸４の吸気弁用カム１３と排気弁用カム１４に検出子１５をそれぞれ添接させることによって、基準になるカムプロフィールを吸気弁用カム１３と排気弁用カム１４の両方について検出する。このカム形状検出用ユニット５の基準カム軸４の回転に、前記カム軸駆動ユニット３のカム軸２の回転を同期させている。
【０００９】
第１の研磨ユニット８は、カム軸２の吸気弁用カム６を研磨するためのもので、軸線がカム軸２と平行になるように設けた円板状の砥石１６を高速で回転させるとともに、前記カム形状検出用ユニット５が検出した吸気弁用カム１３のカムプロフィールに倣うように砥石１６をカム軸２の径方向に平行移動させて吸気弁用カム６に押付ける構造を採っている。砥石１６の回転方向は、カム軸２の回転方向とは反対方向になるように設定している。また、この第１の研磨ユニット８は、カム軸２の３箇所に形成されている吸気弁用カム６を順次研磨するために、基台１７（図１参照）にカム軸２の軸線方向に沿って移動自在に支持させている。
第２の研磨ユニット９は、カム軸２の排気弁用カム７を研磨するためのもので、前記第１の研磨ユニット８と同様に円板状の砥石１８を高速で回転するように設けるとともに、カム形状検出用ユニット５が検出した排気弁用カム１４のカムプロフィールに倣って砥石１８を平行移動させて排気弁用カム７に押付ける構造を採り、前記第１の研磨ユニット８とはカム軸２の径方向の反対側に配設している。この第２の研磨ユニット９の砥石１８の回転方向は、第１の研磨ユニット８の砥石１６と同一方向に設定している。第２の研磨ユニット９もカム軸２の３箇所の排気弁用カム７を研磨できるように、基台１７にカム軸２の軸線方向に沿って移動自在に支持させている。この実施の形態では、第１の研磨ユニット８の砥石１６の軸線と、第２の研磨ユニット９の砥石１８の軸線と、カム軸２の軸線とが同一平面上に位置するようにしている。このように第１の研磨ユニット８と第２の研磨ユニット９を配設することによって、二つの砥石１６，１８をカム軸２の径方向の一方と他方とからそれぞれカム６，７に押付けることができる。
【００１０】
荷重受け部材１０は、図３に示すように、２個のローラ１９，１９をカム軸２の軸部分２ａに添接させる構造を採り、第１の研磨ユニット８側と第２の研磨ユニット９側とに配設している。すなわち、荷重受け部材１０は、図２に示すように、第１の研磨ユニット８側に設けられた第１の荷重受け部材１０ａと、第２の研磨ユニット９側に設けられた第２の荷重受け部材１０ｂとから構成されている。
第１および第２の研磨ユニット８，９はカム６，７に接離するように移動するため、これらの荷重受け部材１０は、カム軸２に対する位置が変化することがないように、この実施の形態では基台１７に支持させている。
第１の研磨ユニット８に設けた第１の荷重受け部材１０ａは、排気弁用カム７を挟んで第１の研磨ユニット８の砥石１６とは反対側に配置し、この砥石１６と同方向からカム軸２に添接させている。第２の研磨ユニット９に設けた第２の荷重受け部材１０ｂは、吸気弁用カム６を挟んで第２の研磨ユニット９の砥石１８とは反対側に配置し、この砥石１８と同方向からカム軸２に添接させている。このように二つの荷重受け部材１０ａ，１０ｂを配置することによって、前記二つの砥石１６，１８をカム６，７にそれぞれ押付けたときにカム軸２に生じる回転モーメント（図２において反時計方向の回転モーメント）を相殺することができる。
【００１１】
上述したように構成したカム軸用研磨装置１は、カム軸２が基準カム軸４と同期して回転し、第１の研磨ユニット８の砥石１６と第２の研磨ユニット９の砥石１８が基準カム軸４の吸気弁用カム１３と排気弁用カム１４のカムプロフィールと一致するように吸気弁用カム６と排気弁用カム７を研磨する。研磨時には、第１の研磨ユニット８の砥石１６を吸気弁用カム６に押付ける力を第２の研磨ユニット９の砥石１８と荷重受け部材１０とによって受けることができ、第２の研磨ユニット９の砥石１８を排気弁用カム７に押付ける力を第１の研磨ユニット８の砥石１６と荷重受け部材１０とによって受けることができる。
【００１２】
したがって、このカム軸用研磨装置１は、砥石を二つ使用する構造を採っているにもかかわらず、荷重受け部材１０は砥石を一つだけ使用する構造を採る場合と同数、すなわち２個でよい。また、第１の研磨ユニット８の砥石１６で吸気弁用カム６を研磨するとともに、第２の研磨ユニット９の砥石１８で排気弁用カム７を研磨する構造を採っており、同一の気筒の吸気弁と排気弁を駆動する吸気弁用カム６と排気弁用カム７を一方の砥石１６と他方の砥石１８とで研磨できるから、二つの砥石１６，１８を軸線方向に近接させることができる。このため、一方の砥石の押圧力を受ける他方の砥石と荷重受け部材１０との間隔を狭めることができ、カム軸２が撓むのを確実に阻止することができる。
【００１３】
上述した実施の形態では、同一の気筒の吸気弁用カム６と排気弁用カム７を第１の研磨ユニット８と第２の研磨ユニット９とによって研磨する例を示したが、これら両ユニット８，９で同時に研磨するカムは、適宜変更することができる。例えば、第１の研磨ユニット８で図２において左側の端部に位置する吸気弁用カム６を研磨し、第２の研磨ユニット９で同図において右側の端部に位置する排気弁用カム７を研磨してもよい。また、本発明に係るカム軸用研磨装置１で研磨するカム軸２は、３気筒エンジンに使用するものに限定されることはなく、単気筒用エンジン用のものや、４気筒エンジン用のもの、またはＤＯＨＣ型多気筒・単気筒エンジンの吸気カム軸、排気カム軸などでもよい。
【００１４】
また、上述した実施の形態では、基準になるカム軸４に倣うように二つの研磨ユニット８，９を制御する例を示したが、本発明に係る研磨装置は、二つの研磨ユニット８，９をＮＣ装置によって制御してもよい。さらに、研磨ユニットは二つに限定されることはなく、研磨ユニットの数量は適宜変更することができる。
【００１５】
【発明の効果】
以上説明したように本発明によれば、一方の砥石をカムに押付ける力を他方の砥石と荷重受け部材とによって受けることができるから、砥石を二つ使用する構造であるにもかかわらず、荷重受け部材は砥石を一つだけ使用する構造を採る場合と同数でよい。したがって、構造の簡素化を図りながら、二つの砥石で同時にカムを研磨して生産性を向上させることができる。
また、本発明によれば、二つの砥石を吸気弁用カムと排気弁用カムとにそれぞれ押付けたときにカム軸に生じる回転モーメントを相殺することができる。
さらに、本発明によれば、同一の気筒の吸気弁と排気弁を駆動する吸気弁用カムと排気弁用カムを一方の砥石と他方の砥石とで研磨することによって、二つの砥石を軸線方向に近接させることができるから、一方の砥石の押圧力を受ける他方の砥石と荷重受け部材との間隔を狭めることができ、カム軸が撓むのを確実に阻止することができる。このため、カム面を高精度に研磨することができる。
【図面の簡単な説明】
【図１】本発明に係るカム軸２用研磨装置１の概略構成を示す平面図である。
【図２】カム軸２と砥石を拡大して示す平面図である。
【図３】砥石と荷重受け部材１０の側面図である。
【符号の説明】
１…カム軸用研磨装置、２…カム軸、６…吸気弁用カム、７…排気弁用カム、８…第１の研磨ユニット、９…第２の研磨ユニット、１０…荷重受け部材、１６，１８…砥石。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camshaft polishing apparatus for polishing a cam of an engine camshaft with a grindstone.
[0002]
[Prior art]
Conventionally, this type of camshaft polishing apparatus employs a structure that holds both ends of the camshaft and presses a grindstone that rotates at a high speed against the cam of the camshaft that rotates at a low speed. One grindstone is used for each camshaft, and is advanced and retracted with respect to the cam in accordance with a reference cam profile. The polishing apparatus also includes a load receiving member that prevents the camshaft from being bent by the pressing force of the grindstone. The load receiving member is disposed so as to be in contact with the shaft portions on both sides of the cam to be polished, at a position symmetrical to the grindstone as viewed from the axial direction of the cam shaft.
[0003]
[Problems to be solved by the invention]
The conventional camshaft polishing apparatus configured as described above has a structure in which all the cams are sequentially polished with one grindstone, and there is a limit to improving productivity. Such a problem can be solved by increasing the number of grindstones. However, the number of load receiving members must be increased by the increase in the number of grindstones, which complicates the structure of the polishing apparatus.
[0004]
The present invention has been made to solve such problems, and provides a camshaft polishing apparatus that improves productivity while preventing the structure from becoming complicated due to an increase in load receiving members. Objective.
[0005]
[Means for Solving the Problems]
In order to achieve this object, a camshaft polishing apparatus according to the present invention holds both ends of a camshaft, and rotates and presses a grindstone against an intake valve cam and an exhaust valve cam of the camshaft. In the shaft polishing apparatus, a first polishing unit having a grindstone pressed against the intake valve cam from one of the camshaft radial directions and a grindstone pressed against the exhaust valve cam from the other camshaft radial direction. 2 and the camshaft for the exhaust valve in the axial direction of the camshaft are arranged on the opposite side of the grindstone of the first grindstone unit and are attached to the camshaft from the same direction as the grindstone of the first grindstone unit. The first load receiving member and the camshaft for the second polishing unit are arranged on the opposite side of the camshaft for the second polishing unit with the intake valve cam interposed in the axial direction of the camshaft. A second load receiving member to be attached; It is one that is equipped.
According to the present invention, the force for pressing one of the grindstones against the cam can be received by the other grindstone and the load receiving member. That is, it is possible to cancel the rotational moment generated in the cam shaft when the two grindstones are pressed against the intake valve cam and the exhaust valve cam, respectively.
Further, according to the present invention, the two grindstones are axially polished by polishing the intake valve cam and the exhaust valve cam for driving the intake valve and the exhaust valve of the same cylinder with one grindstone and the other grindstone. Can be close. For this reason, the space | interval of the other grindstone which receives the pressing force of one grindstone, and a load receiving member can be narrowed, and it can prevent reliably that a cam shaft bends.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a camshaft polishing apparatus according to the present invention will be described in detail with reference to FIGS. 1 is a plan view showing a schematic configuration of a camshaft polishing apparatus according to the present invention, FIG. 2 is an enlarged plan view showing a camshaft and a grindstone, and FIG. 3 is a side view of the grindstone and a load receiving member. FIG. 3 is a sectional view taken along line III-III in FIG. 2.
In these drawings, reference numeral 1 denotes a camshaft polishing apparatus according to this embodiment. The polishing apparatus 1 is for polishing a camshaft 2 used in a three-cylinder engine, and supports a camshaft drive unit 3 that supports both ends of the camshaft 2 and rotates at low speed, and a reference camshaft 4. And a first polishing unit 8 for polishing the intake valve cam 6 and the exhaust valve cam 7 of the cam shaft 2 according to the cam profile detected by the cam shape detection unit 5. And a second polishing unit 9 and a load receiving member 10 (see FIGS. 2 and 3).
[0008]
The cam shaft drive unit 3 holds both ends of the cam shaft 2 with chucks 11 and 12, respectively, and rotates the cam shaft 2 at a low speed by a motor (not shown) connected to the chuck 11 located on the left side in FIG. The structure to make it take is adopted.
The cam shape detection unit 5 rotates a reference cam shaft 4 different from the cam shaft 2 to be polished at a low speed, and a detector 15 is connected to the intake valve cam 13 and the exhaust valve cam 14 of the reference cam shaft 4. , The reference cam profile is detected for both the intake valve cam 13 and the exhaust valve cam 14. The rotation of the cam shaft 2 of the cam shaft drive unit 3 is synchronized with the rotation of the reference cam shaft 4 of the cam shape detection unit 5.
[0009]
The first polishing unit 8 is for polishing the intake valve cam 6 of the camshaft 2, and rotates a disc-shaped grindstone 16 provided so that the axis is parallel to the camshaft 2 at high speed. The grindstone 16 is moved parallel to the radial direction of the cam shaft 2 and pressed against the intake valve cam 6 so as to follow the cam profile of the intake valve cam 13 detected by the cam shape detection unit 5. . The rotating direction of the grindstone 16 is set to be opposite to the rotating direction of the camshaft 2. Further, the first polishing unit 8 has a base 17 (see FIG. 1) in the axial direction of the camshaft 2 in order to polish the intake valve cams 6 formed at three locations on the camshaft 2 sequentially. It is supported so that it can move along it.
The second polishing unit 9 is for polishing the exhaust valve cam 7 of the camshaft 2 and, like the first polishing unit 8, is provided with a disk-shaped grindstone 18 so as to rotate at high speed. The grindstone 18 is moved in parallel with the cam profile of the exhaust valve cam 14 detected by the cam shape detection unit 5 and is pressed against the exhaust valve cam 7. The first polishing unit 8 is a cam. It is disposed on the opposite side of the shaft 2 in the radial direction. The rotation direction of the grindstone 18 of the second polishing unit 9 is set in the same direction as the grindstone 16 of the first polishing unit 8. The second polishing unit 9 is also supported by the base 17 so as to be movable along the axial direction of the cam shaft 2 so that the three exhaust valve cams 7 of the cam shaft 2 can be polished. In this embodiment, the axis of the grindstone 16 of the first polishing unit 8, the axis of the grindstone 18 of the second polishing unit 9, and the axis of the camshaft 2 are located on the same plane. By disposing the first polishing unit 8 and the second polishing unit 9 in this way, the two grindstones 16 and 18 are pressed against the cams 6 and 7 from one side and the other side of the cam shaft 2 in the radial direction, respectively. be able to.
[0010]
As shown in FIG. 3, the load receiving member 10 has a structure in which two rollers 19, 19 are brought into contact with the shaft portion 2 a of the cam shaft 2, and the first polishing unit 8 side and the second polishing unit 9 are arranged. It is arranged on the side. That is, as shown in FIG. 2, the load receiving member 10 includes a first load receiving member 10 a provided on the first polishing unit 8 side and a second load provided on the second polishing unit 9 side. It is comprised from the receiving member 10b.
Since the first and second polishing units 8 and 9 move so as to be in contact with and away from the cams 6 and 7, these load receiving members 10 are arranged so as not to change their positions with respect to the cam shaft 2. In this form, it is supported by the base 17.
The first load receiving member 10 a provided in the first polishing unit 8 is disposed on the opposite side of the grindstone 16 of the first polishing unit 8 with the exhaust valve cam 7 interposed therebetween, and from the same direction as the grindstone 16. It is in contact with the camshaft 2. Second load receiving member 10b provided in the second polishing unit 9 is disposed on the opposite side of the grinding wheel 18 of the second polishing unit 9 across the intake valve cam 6, the same direction as the grinding wheel 18 It is in contact with the camshaft 2. By arranging the two load receiving members 10a and 10b in this way, the rotational moment generated in the camshaft 2 when the two grindstones 16 and 18 are pressed against the cams 6 and 7 (counterclockwise in FIG. 2). (Rotational moment) can be offset.
[0011]
In the camshaft polishing apparatus 1 configured as described above, the camshaft 2 rotates in synchronization with the reference camshaft 4, and the grindstone 16 of the first polishing unit 8 and the grindstone 18 of the second polishing unit 9 are the reference. The intake valve cam 6 and the exhaust valve cam 7 are polished so as to coincide with the cam profiles of the intake valve cam 13 and the exhaust valve cam 14 of the cam shaft 4. At the time of polishing, the force for pressing the grindstone 16 of the first polishing unit 8 against the intake valve cam 6 can be received by the grindstone 18 of the second polishing unit 9 and the load receiving member 10. The force for pressing the grindstone 18 against the exhaust valve cam 7 can be received by the grindstone 16 of the first polishing unit 8 and the load receiving member 10.
[0012]
Therefore, although this camshaft polishing apparatus 1 has a structure using two grindstones, the load receiving member 10 has the same number as that of a structure using only one grindstone, that is, two. Good. In addition, the intake valve cam 6 is polished by the grindstone 16 of the first polishing unit 8 and the exhaust valve cam 7 is polished by the grindstone 18 of the second polishing unit 9. Since the intake valve cam 6 and the exhaust valve cam 7 that drive the intake valve and the exhaust valve can be polished by one grindstone 16 and the other grindstone 18, the two grindstones 16 and 18 can be brought close to each other in the axial direction. . For this reason, the space | interval of the other grindstone which receives the pressing force of one grindstone, and the load receiving member 10 can be narrowed, and it can prevent reliably that the cam shaft 2 bends.
[0013]
In the above-described embodiment, an example in which the intake valve cam 6 and the exhaust valve cam 7 of the same cylinder are polished by the first polishing unit 8 and the second polishing unit 9 has been described. , 9 can be changed as appropriate. For example, the intake valve cam 6 positioned at the left end in FIG. 2 is polished by the first polishing unit 8, and the exhaust valve cam 7 positioned at the right end in FIG. 2 is polished by the second polishing unit 9. May be polished. Further, the camshaft 2 polished by the camshaft polishing apparatus 1 according to the present invention is not limited to that used for a three-cylinder engine, and is for a single-cylinder engine or a four-cylinder engine. Alternatively, an intake cam shaft , an exhaust cam shaft , or the like of a DOHC type multi-cylinder / single-cylinder engine may be used.
[0014]
In the above-described embodiment, the example in which the two polishing units 8 and 9 are controlled so as to follow the reference cam shaft 4 is shown. However, the polishing apparatus according to the present invention has two polishing units 8 and 9. May be controlled by the NC unit. Furthermore, the number of polishing units is not limited to two, and the number of polishing units can be changed as appropriate.
[0015]
【The invention's effect】
As described above, according to the present invention, since the force for pressing one of the grindstones against the cam can be received by the other grindstone and the load receiving member, the structure uses two grindstones. The number of load receiving members may be the same as when a structure using only one grindstone is employed. Therefore, the productivity can be improved by simultaneously polishing the cam with two grindstones while simplifying the structure.
Further, according to the present invention, it is possible to cancel the rotational moment generated in the cam shaft when the two grindstones are pressed against the intake valve cam and the exhaust valve cam, respectively.
Further, according to the present invention , the two grindstones are axially polished by polishing the intake valve cam and the exhaust valve cam for driving the intake valve and the exhaust valve of the same cylinder with one grindstone and the other grindstone. Therefore, the distance between the other grindstone that receives the pressing force of one grindstone and the load receiving member can be reduced, and the camshaft can be reliably prevented from being bent. For this reason, the cam surface can be polished with high accuracy.
[Brief description of the drawings]
FIG. 1 is a plan view showing a schematic configuration of a polishing apparatus 1 for a camshaft 2 according to the present invention.
FIG. 2 is an enlarged plan view showing a camshaft 2 and a grindstone.
3 is a side view of a grindstone and a load receiving member 10. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cam shaft grinding | polishing apparatus, 2 ... Cam shaft, 6 ... Intake valve cam, 7 ... Exhaust valve cam, 8 ... 1st grinding | polishing unit, 9 ... 2nd grinding | polishing unit, 10 ... Load receiving member, 16 , 18 ... Whetstone.

Claims

In the camshaft polishing device that holds both ends of the camshaft and rotates and presses a grindstone against the intake valve cam and the exhaust valve cam of the camshaft .
A first polishing unit having a grindstone pressed against the intake valve cam from one radial direction of the camshaft;
A second polishing unit having a grindstone pressed against the exhaust valve cam from the other radial direction of the camshaft;
A first load receiving member that is disposed on the opposite side of the grinding wheel of the first polishing unit across the exhaust valve cam in the axial direction of the cam shaft and is in contact with the cam shaft from the same direction as the grinding wheel of the first polishing unit When,
A second load receiving member that is disposed on the opposite side of the grinding wheel of the second polishing unit across the intake valve cam in the axial direction of the cam shaft and that is in contact with the cam shaft from the same direction as the grinding wheel of the second polishing unit And a camshaft polishing apparatus.