GB2455913A

GB2455913A - Grinding apparatus

Info

Publication number: GB2455913A
Application number: GB0823443A
Authority: GB
Inventors: Kiyotaka Inque
Original assignee: Musashi Seimitsu Industry Co Ltd
Current assignee: Musashi Seimitsu Industry Co Ltd
Priority date: 2007-12-27
Filing date: 2008-12-23
Publication date: 2009-07-01
Also published as: GB0823443D0; JP2009154262A

Abstract

Grinding apparatus includes a grindstone 5 rotatable about a grindstone rotational axis (X1 fig 1) and relatively movable with respect to a work such as a cam shaft blank 19, the grindstone 5 being formed by adhering grinding grains to a core 6, the core 6 including a core parallel part 6a parallel with the grindstone rotational axis (X1 fig 1) and at least one core projecting part 6b, continuous with at least one axially opposed end of the core parallel part 6a and having a diameter larger than that of the core parallel part 6a; and the grinding grains 7 such as CBN are adhered to surfaces of both the core parallel part 6a and the at least one core projecting part 6b. Several core projecting parts 6b may be provided, continuous with opposing ends of the core parallel part 6a. The at least one core projecting part 6b may include a core perpendicular surface (6i fig. 3) perpendicular to the grindstone axis (X1 fig 1), a core concave surface (6g fig. 3), one end of which is continuous with the core perpendicular surface (6i fig. 3) and the other end of which is continuous with the core parallel part 6a. The concave surface (6g fig. 3) avoids a connection part between surfaces of the work having a round shape (123h fig 9) when it should have an acute angle (23h fig. 7).

Description

1 2455913 Grinding Apparatus

FIELD OF THE INVENTION

The present invention relates to a grinding apparatus for grinding an outer circumferential surface of a work by means of a grindstone.

BACKGROUND ART

There has been known a conventional technique for grinding an outer circumferential surface of a cam-shaft blank, which has been formed by casting, by means of a grindstone so as to form a groove between a first cam lobe and a second cam lobe (see, JP2004-36662A).

In addition, there has been known a technique for grinding an outer circumferentia' surface of a cam-shaft blank by means of a grindstone so as to form a cam lobe whose cross-section perpendicular to an axis line thereof is S..

: non-circular (see, JP Patent No. 3850224). *ISS * S S...

SUMMARY OFTHE INVENTION

*...*.

When a groove is ground in an outer circumferential surface of a work, such as a cam shaft, and also an outer :. circumferential surface of a projecting part, such as a cam lobe and a journal adjacent to the groove, is ground, it is general to * .: 25 firstly grind the groove in the outer circumferential surface of the work by means of a first grindstone, and thereafter to grind the outer circumferential surface of the projecting part adjacent to the groove by means of a second grindstone that is different from the first grindstone. Namely, it is general that the groove is firstly ground by a first grinding apparatus having the first grindstone, and subsequently the outer circumferential surface of the projecting part adjacent to the groove is ground by a second grinding apparatus having the second grindstone.

However, this grinding method is disadvantageous in that a total process period for the outer circumferential surface of the work is long.

In addition, the grindstone used for grinding the outer circumferential surface of the work is formed by electro-depositing grinding grains, such as CBN, of a predetermined size onto the outer circumferential surface of a core. Herein, in general, an end (nose) of a tip for cutting the core has a nose radius of about 0.4 mm, in order that the end of the tip does not crack off. Thus, when a core is cut and processed by such a tip, as shown in Figs. 8 and 9, a core connection part 106h, which is located between a core parallel part 106a formed on an outer circumferential surface of a core 106 so as to be in parallel with a grindstone rotational axis and a core perpendicular part 106e formed thereon so as to be perpendicular to the grindstone rotational axis, is cut into a round shape corresponding to the nose radius of the tip end.

Then, when grinding grains 107 are adhered to the round-shaped core connection part 106h, the grinding grains 107 are also positioned along the round contour thereof. When S...

: a work 120 is ground by the thus formed grindstone 105, a *.S.

connection part 123h between an outer circumferential surface 123a and a side surface 123e of a projecting part 123 of the * work 120 is correspondingly ground into a round shape, even when the connection part 123h should have an acute angle.

The present invention has been made in view of the :::: above circumstances. The object of the present invention is to * 25 provide a grinding apparatus capable of performing a grinding process for a short period of time, when a groove is ground in an outer circumferential surface of a work and a projecting part adjacent to the groove is ground. Another object of the present invention is to provide a grinding apparatus capable of grinding the connection part with an improved grinding accuracy, when a connection part between an outer circumferential surface and a side surface of a work is ground.

The present invention is a grinding apparatus in which a grindstone formed by adhering grinding grains to a core is held so as to be rotatable about a grindstone rotational axis and to be relatively movable with respect to a work, wherein: the core includes: a core parallel part in parallel with the grindstone rotational axis; and core projecting parts which are continuous with axially opposed ends of the core parallel part and have diameters larger than that of the core parallel part; and the grinding grains are adhered to surfaces of both the core parallel part and the core projecting parts.

According to the present invention, simultaneously with an outer circumferential surface of a projecting part of a work being ground by the core parallel part, grooves adjacent to axially opposed ends of the projecting part of the work can be ground by the core projecting parts. Accordingly, for a case wherein a groove is ground in an outer circumferential surface of a work and a projecting part adjacent to the groove is ground, the grinding process can be performed for a short period of time.

Alternatively, the present invention is a grinding apparatus in which a grindstone formed by adhering grinding grains to a core is held so as to be rotatable about a grindstone S...

rotational axis and to be relatively movable with respect to a work, wherein: the core includes: a core parallel part in parallel * ****.

* with the grindstone rotational axis; and a core projecting part which is continuous with at least one axial end of the core parallel part and has a diameter larger than that of the core :: : parallel part; the core projecting part has, on the side of the * 25 core parallel part, a core parallel-part-side surface continuous with the core parallel part; the core parallel-part-side surface has: a core perpendicular surface perpendicular to the grindstone rotational axis; and a core concaved surface which is concaved farther away from the core parallel part than the core perpendicular surface, with one end of the core concaved surface being continuous with the core perpendicular surface and the other end thereof being continuous with the core parallel part; and the grinding grains are adhered to surfaces of both the core parallel part and the core projecting part.

According to the present invention, since the core concaved surface is concaved, the grinding grains adhered to the core concaved surface are located on a position concaved from a position of the grinding grains adhered to the core perpendicular surface, or the grinding grains adhered to the core concaved surface are less convex toward the work as compared with the grinding grains adhered to the core perpendicular surface. Thus, in a projecting part of the work, a connection part between an outer circumferential surface of the projecting part and a side surface thereof can be effectively prevented from being ground into a round shape. Alternatively, an area that is ground into a round shape and a round degree of the round shape can be reduced. Accordingly, when a connection part between an outer circumferential surface and a side surface of a work is ground by a grindstone, the connection part can be ground with an improved grinding accuracy (more specifically, with a desired acute-angle accuracy).

BRIEF DESCRIPTION OF THE DRAWINGS

: Fig. 1 is a partial sectional view showing a grinding apparatus according to one embodiment of the present invention, and a work that has been ground by the grinding S.....

* apparatus.

Fig. 2 is a partial sectional view showing a state immediately before a grinding process, in which grooves are ground in an outer circumferential surface of a work and side * 25 surfaces of projecting parts adjacent to the grooves are ground, by means of the grinding apparatus of the present embodiment.

Fig. 3 is an enlarged view of a main part of Fig. 2.

Fig. 4 is a partial sectional view showing a first-phase grinding state of the grinding process, in which the grooves are ground in the outer circumferential surface of the work and the side surfaces of the projecting parts adjacent to the grooves are ground, by means of the grinding apparatus of the present embodiment.

Fig. 5 is a partial sectional view showing a second-phase grinding state of the grinding process, in which the grooves are ground in the outer circumferential surface of the work and the side surfaces of the projecting parts adjacent to the grooves are ground, by means the grinding apparatus of the present embodiment.

Fig. 6 is a partial sectional view showing a third-phase grinding state of the grinding process, in which the grooves are ground in the outer circumferential surface of the work and the side surfaces of the projecting parts adjacent to the grooves are ground, by means of the grinding apparatus of the present embodiment.

Fig. 7 is an enlarged view of a main part of Fig. 6.

Fig. 8 is a partial sectional view showing a third-phase grinding state of a grinding process, in which groove are ground in an outer circumferential surface of a work and side surfaces of a projecting part adjacent to the grooves are ground, by means of a conventional grinding apparatus.

Fig. 9 is an enlarged view of a main part of Fig. 8. SI..

: BEST MODE FOR CARRYING OUT THE INVENTION

*::::* An embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a partial sectional view showing a grinding apparatus according to one embodiment of the present invention, and a work that has been ground by the grinding apparatus. Fig. 2 is a partial sectional :: view showing a state immediately before a grinding process, in * ** 25 which grooves are ground in an outer circumferential surface of a work and side surfaces of projecting parts adjacent to the grooves are ground, by means of the grinding apparatus of the present embodiment. Fig. 3 is an enlarged view of a main part of Fig. 2. Fig. 4 is a partial sectional view showing a first-phase grinding state of the grinding process by means of the grinding apparatus of the present embodiment. Fig. S is a partial sectional view showing a second-phase grinding state of the grinding process by means of the grinding apparatus of the present embodiment. Fig. 6 is a partial sectional view showing a third-phase grinding state of the grinding process by means of the grinding apparatus of the present embodiment. Fig. 7 is an enlarged view of a main part of Fig. 6.

At first, a cam shaft 20, which is an example of the work, is described with reference to Fig. 1. The cam shaft 20 is used for a valve control of a multi-cylinder engine. A plurality of cam lobes 23, 24, 25, and a journal 26, which are examples of the projecting parts, are formed in an axial direction at respective predetermined intervals therebetween. Between the plurality of cam lobes 23, 24, 25 and the journal 26, there are formed a plurality of grooves 21 and 22.

The plurality of cam lobes 23, 24, and 25 have non-circular sectional surfaces perpendicular to the axis line, and respectively have semi-circular base parts 23m, 24m, and 25m, and cam-top parts 23n, 24n, and 25n projecting outward from the base parts.

As shown in Fig. 2, the cam shaft 20 is formed by grinding an outer circumferential surface of a cam-shaft blank 19, which has been drawn out from a die, not shown, by means : of a grinding apparatus 1. Namely, the cam-shaft blank 19 is S...

formed radially and axially larger than the plurality of cam lobes 23, 24, 25 and the journal 26 and the plurality grooves 21 and * 22, which are to be formed from the cam-shaft blank 19. That is, the cam- shaft blank 19 includes a margin 18 of predetermined dimensions.

As shown in Fig. 1, the grinding apparatus 1 is provided * 25 with a grindstone 5 supported by a shaft member 2 of a grindstone rotating apparatus. The grindstone 5 is interposed between mounting plates 3 and 4, and is rotatable about a grindstone rotational axis Xl. On the other hand, a cam-shaft rotating apparatus (not shown) is arranged in parallel with the grindstone rotational axis Xl. The cam-shaft rotating apparatus is configured to rotate the cam-shaft blank 19 about a cam-shaft rotational axis X2 (which is adjusted so as to be in parallel with the grindstone rotational axis Xl), while supporting opposed ends of the cam-shaft blank 19.

Next, the grindstone 5 is described with reference to Fig. 2. The grindstone 5 is formed by electro-depositing a plurality of grinding grains 7, made of CBN or the like, onto an outer circumferential surface of a core 6, by an adhesive 8 such as nickel plating. The core 6 has a core parallel part 6a in parallel with the grindstone rotational axis Xl, and core projecting parts Gb which are continuous with axially opposed ends of the core parallel part 6a and have diameters larger than that of the core parallel part 6a.

Each of the core projecting parts 6b has, on an outer circumferential surface thereof, a core larger-diameter parallel part 6d having a diameter larger than that of the core parallel part 6a. Further,the core projecting part 6b has, on a side of the core parallel part 6a, a core parallel-part-side surface 6e continuous with the core parallel part 6a. On the other side opposed to the core parallel part 6a, the core projecting part 6b has a core outside surface 6f. Further, the core projecting part 6b has a core inside round part 6j of a round shape between the core larger-diameter parallel part 6d and the core : parallel-part-side surface 6e, and a core outside round part 6k of a round shape between the core larger-diameter parallel part 6d and the core outside surface 6f.

*S*S..

* * The core parallel-part-side surface 6e is described in detail with reference to Figs. 1 to 3. The core parallel-part-side surface 6e has a core perpendicular surface 6i that is perpendicular to the grindstone rotational axis Xl, and a core * ** 25 concaved surface 6g that is concaved from the core perpendicular surface 6i to a side of the core outside surface 6f, with one end of the core concaved surface 6g being continuous with the core perpendicular surface 6i and the other end thereof being continUous with the core parallel part 6a (in the core concaved surface 6g, a portion connected to the core parallel part 6a is also shown as a core connection part 6h.) Next, a method for grinding the grooves 21 and 22 in the outer circumferential surface of the cam-shaft blank 19 and for grinding the cam lobe 23 and/or the journal 26 adjacent to the grooves 21 and 22 is described with reference to Figs. 1 to 7.

The grindstone 5 fitted to the grindstone rotating apparatus (details thereof are not shown) is rotated about the grindstone rotational axis Xl. Meanwhile, the cam-shaft blank 19 fitted to the cam-shaft rotating apparatus (details thereof are not shown) is rotated about the cam-shaft rotational axis X2.

Then, as shown in Fig. 2, the rotating grindstone 5 is relatively moved toward the rotating cam-shaft blank 19 in a direction perpendicular to the cam-shaft rotational axis X2.

After the rotating grindstone 5 has been brought into contact with the cam-shaft blank 19, the grindstone 5 repeatedly moves forward and rearward in accordance with the shape of the cam lobe 23.

By repeating the forward and rearward movement, the grinding grains 7 adhered to the core outside surface 6f grind the cam-shaft blank 19. Thus, as shown in Fig. 4, there are firstly formed a side surface 24e of the cam lobe 24 and a side surface 25e of the cam lobe 25. *S.S

As the grinding process proceeds, as shown in Fig. 5, in addition to the grinding of the side surface 24e of the cam lobe 24 and of the side surface 25e of the cam lobe 25 by the grinding grains 7 adhered to the core outside surface 6f, the grinding grains 7 adhered to the core parallel part 6a grind an outer circumferential surface 23a of the cam lobe 23. Further, the grinding grains 7 adhered to the (right and left) core : 25 perpendicular surfaces 6i of the core parallel-part-side surfaces 6e of the core projecting parts 6b grind the opposed side surfaces 23e of the cam lobe 23. At the same time, the grinding grains 7 adhered to the core larger-diameter parallel parts 6d of the core projecting parts 6b, adhered to the core inside round parts 6j of the core projecting parts 6b, and adhered to the core outside round parts 6k of the core projecting parts 6b start to grind and form the groove 21 between the cam lobe 24 and the cam lobe 23 as well as the groove 22 between the cam lobe 23 and the cam lobe 25.

As the grinding process further proceeds, as shown in Fig. 6 and 7, the side surface 24e of the cam lobe 24 and the side surface 25e of the cam lobe 25 are ground by the grinding grains 7 adhered to the core outside surfaces 6f. In addition, the grinding grains 7 adhered to the core perpendicular surfaces 6i of the core parallel-part-side surfaces 6e of the core projecting parts 6b continuously grind the side surfaces 23e of the cam lobe 23. Simultaneously, the grinding grains 7 adhered to the core parallel part 6a further grind the outer circumferential surface 23a of the cam lobe 23. Also, the grinding grains 7 adhered to core-larger-diameter parallel parts 6d, the core inside round parts 6j, and the core outside round parts 6k of the core projecting parts 6b continuously grind and form the groove 21 between the cam lob 24 and the cam lobe 23 as well as the groove 22 between the cam lobe 23 and the cam lobe 25.

Thereafter, the grindstone 5 is separated from the cam shaft 20, so that the formation of the cam lobe 23 and the grooves 21 and 22 adjacent to the cam lobe 23 is completed.

As shown in Fig. 7, the grinding apparatus 1 of the present embodiment has the following features. Each of the core projecting parts 6b has, on the side of the core parallel part 6a, the core parallel-part-side surface 6e continuous with the core parallel part 6a. The core parallel-part-side surface 6e has the core perpendicular surface 6i perpendicular to the grindstone rotational axis Xl, and the core concaved surface 6g : 25 which is concaved farther away from the core parallel part 6a than the core perpendicular surface 6i, with one end of the core concaved surface 6g being continuous with the core perpendicular surface 6i and the other end thereof being continuous with the core parallel part 6a. The grinding grains 7 are adhered to the surfaces of both the core parallel part 6a and the core projecting parts 6b. Thus, the grinding grains 7 adhered to the core concaved surface 6g are located on a position concaved from a position of the grinding grains 7 adhered to the core perpendicular surface 6i, and therefore are not convex toward the cam lobe 23. As a result, in the projecting part of the cam lobe 23, the connection part 23h between the outer circumferential surface 23a and the side surface 23e can be effectively prevented from being ground into a round shape.

The grooves 21 and 22 are simultaneously ground relative to the outer circumferential surface 23a of the cam lobe 23. Thus, the sectional surfaces of the grooves 21 and 22 perpendicular to the cam-shaft rotational axis X2 are of non-circular shapes that are substantially similar to the shape of the cam lobe 23.

As described above, in the grinding apparatus 1 in which the grindstone 5 formed by adhering the grinding grains 7 to the core 6 is held so as to be rotatable about the grindstone rotational axis Xl and to be relatively movable with respect to the cam shaft 20, the core 6 has the core parallel part 6a in parallel with the grindstone rotational axis Xl, and has the core projecting parts 6b which are continuous with the axially opposed ends of the core parallel part 6a and which have *..* diameters larger than that of the core parallel part 6a, with the grinding grains 7 being adhered to both of the surfaces of the core parallel part 6a and the core projecting parts 6b.

Therefore, simultaneously with the outer circumferential surface 23e of the cam lobe 23 being ground by the core parallel part 6a, the grooves 21 and 22 adjacent to the opposed ends of the cam lobe 23 of the cam shaft 20 can be ground by the core : 25 projecting parts 6b.

Alternatively, in the grinding apparatus 1 in which the grindstone 5 formed by adhering the grinding grains 7 to the core 6 is held so as to be rotatable about the grindstone rotational axis Xl and to be relatively movable with respect to the cam shaft 20, the core 6 has the core parallel part 6a in parallel with the grindstone rotational axis Xl, and has the core projecting part 6b which is continuous with at least one axial end of the core parallel part 6a and which has a diameter larger than that of the core parallel part 6a; the core projecting part 6b has, on the side of the core parallel part 6a, the core parallel-part-side surface 6e continuous with the core parallel part 6a; the core parallel-part-side surface 6e has the core perpendicular surface 61 perpendicular to the grindstone rotational axis Xl, and the core concaved surface 6g which is concaved farther away from the core parallel part 6a than the core perpendicular surface 6i, with one end of the core concaved surface 6g being continuous with the core perpendicular surface 6i and the other end thereof being continuous with the core parallel part 6a; and the grinding grains 7 are adhered to both of the surfaces of the core parallel part 6a and the core projecting part 6b. Therefore, the grinding grains 7 adhered to the core concaved surface 6g are located on a position concaved from a position of the grinding grains 7 adhered to the core perpendicular surface 6i. As a result, in the cam lobe 23 of the cam shaft 20, the connection part 23h between the outer circumferential surface 23a and the side surface 23e can be effectively prevented from being ground into a round shape.

: In the above embodiment, due to the provision of the core concaved surface 6g, the grinding grains 7 adhered to the core concaved surface 6g are concaved from the grinding grains 7 adhered to the core perpendicular surface 6i to the side of the core outside surface 6f. However, a case in which the grinding grains 7 adhered to the core concaved surface 6g are coplanar :: with the grinding grains 7 adhered to the core perpendicular : 25 surface 6i is not excluded from the present invention at least upon the filing of this patent application. In addition, an embodiment in which the grinding grains 7 adhered to the core concaved surface 6g are somewhat convex toward the side of the cam lobe 23 as compared with the grinding grains 7 adhered to the core perpendicular surface 6i is not excluded from the present invention at least upon the filing of this patent application. In this case, the connection part 23h between the outer circumferential surface 23a and the side surface 23e in the thus formed cam lobe 23 is somewhat likely to have a round shape (in this case, the effect of the present invention resides in that the degree of the round shape is smaller than conventional cases).

In the above embodiment, although the cam shaft is taken as an example of a work having grooves and projecting parts adjacent to the grooves, the present invention can be applied to various other products. a... * a * * * *... * * *I*. * S S..

S S * * S. a *5 * * S* *.

Claims

1. A grinding apparatus in which a grindstone formed by adhering grinding grains to a core is held so as to be rotatable about a grindstone rotational axis and to be relatively movable with respect to a work, wherein: the core includes: a core parallel part in parallel with the grindstone rotational axis; and core projecting parts which are continuous with axially opposed ends of the core parallel part and have diameters larger than that of the core parallel part; and the grinding grains are adhered to surfaces of both the core parallel part and the core projecting parts.

*:

2. A grinding apparatus in which a grindstone formed by adhering grinding grains to a core is held so as to be rotatable about a grindstone rotational axis and to be relatively movable with respect toawork, *..

* wherein: *:::: the core includes: a core parallel part in parallel with the grindstone rotational axis; and a core projecting part which is continuous with at least one axial end of the core parallel part and has a diameter larger than that of the core parallel part; the core projecting part has, on the side of the core parallel part, a core parallel-part-side surface continuous with the core parallel part; the core parallel-part-side surface has: a core perpendicular surface perpendicular to the grindstone rotational axis; and a core concaved surface which is concaved farther away from the core parallel part than the core perpendicular surface, with one end of the core concaved surface being continuous with the core perpendicular surface and the other end thereof being continuous with the core parallel part; and the grinding grains are adhered to surfaces of both the core parallel part and the core projecting part.

3. A grinding apparatus substantially as described herein with reference to the accompanying Figures 1 to 9. * I è I. I 0ISs

I I * IS.

S 11... * .

I I..

S * S.. I * * S. I S. 5 * SS I.