SURFACE GRINDING MACHINE

Abstract: A surface grinding machine capable of grinding the end surface of a workpiece (10) without leaving any unground protruding portion at the centre thereof by imparting rotation on its own axis and around a chuck holder or eccentric rotation to either a chuck (14) for holding the workpiece (10) or a cup-shaped grinding wheel (12) by a planetary gear mechanism (25, 26).

Description: The present invention relates to a "face grinder" or surface grinding machine used for grinding, for example, the end surface of a cylindrical workpiece. A surface grinding machine having the structure shown in Figs. 4 to 7 is generally known and comprises too wheel heads 4, one for rough grinding and the other for finishing, which are provided side by side on a support bed 1 and mounted such as to be vertically displaceable thereon. A rotary indexing table 6 is disposed under the wheel heads so as to face such, as shown in Figs. 4 and 5, and a multiplicity of chucks 8 are disposed on the index table 6, as shown in Figs. 6 and 7. The wheel heads 4 are provided with cup-shaped grinding wheels 2 which are rotated by drive motors 3. The table 6 and the chuck 8 are rotated by a drive motor 5 and a drive motor 7, respectively. A workpiece 9 is supplied to the chuck 8 at the loading position of the table 6 and is held by an appropriate method. The grinding wheel 2 cuts the workpiece 9 which is being rotated together with the chuck 8, whereby the end surface of the workpiece 9 is ground to a predetermined dimension. The end surface of the workpiece 9 which has been ground by the known surface grinding machine bears the grinding marks shown in Fig. 8 if the workpiece has a centre hole 9 a and bears the grinding marks shown in Fig. 9 if the workpiece has no centre hole. Accordingly, when the wheel 2 becomes worn locally, the workpiece 9 without a centre hole 9 a has a protruding portion 9 b (see Fig. 10) left unground due to the partial wear of the wheel 2, so that the required working accuracy for the workpiece 9 is not obtained. As a result, the life of the wheel 2 is short, thereby necessitating frequent changes of the wheel, and it is difficult to obtain good working efficiency. Japanese Specification -A-58126051 discloses a surface grinding machining comprising a rotary wheel support or machine head supporting a grinding wheel (3b), at least one chuck (14) carried by a support table (4) or bed for receiving work-pieces to be ground and being disposed facing said grinding wheel (3b) when located on said head, each said chuck (14) and said wheel head including the wheel stock or head are mounted so as to be rotatable (see Figure 4), whereby each said chuck (14) is also mounted so that its rotary axis is eccentrically rotatable by drive means (19-23) about the axis of a chuck holder (5). It will be appreciated that the grinding wheels and supports rotate about a common axis and that each chuck (14) rotates only about its own axis which is fixed relative to rotary support table (4). Accordingly, it is an object of the present invention to provide a surface grinding machine which never or rarely produces a protruding portion due to partial wheel wear, unlike hitherto surface grinding machines. To achieve this aim, a surface grinding machine according to the present invention comprises a rotary wheel support or machine head (11) for supporting a cup-shaped grinding wheel (12) which is vertically displaceable and adjustable, at least one chuck (14) carried by a support table (13,27) or bed for receiving work-pieces (10) to be ground and being disposed facing said grinding wheel (12) when located on said head (11), the or each said chuck (14) and said wheel head (11) including the wheel stock or head (11) are mounted so as to be rotatable; characterised by the feature that the grinding wheel (12) including any wheel stock or head, is mounted on the machine head (11) to extend around and eccentrically relative to the axis of rotation (0') of the rotary grinding wheel support of the machine head (11) and having a single common axis of rotation (0') with said rotary support of the wheel head. The machine head is the rotatable part of the machine which supports the cup-shaped wheel including any wheel stock or head for mounting on the machine head. The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a vertical fragmentary elevational view in part section of a part of a grinding machine according to the invention; Fig. 2 is a horizontal sectional view of the embodiment shown in Fig. 1 taken along the line A - A' of Fig. 1; Fig. 3 is an explanatory schematic plan view illustrating the path of a workpiece under the grinding wheel of the machine of Fig. 2; Fig. 4 is a schematic front elevational view of a conventional surface grinding machine; Fig. 5 is a side elevational view of the machine of Fig. 4; Fig. 6 is a fragmentary vertical section of a part of the machine of Fig. 4; Fig. 7 is a sectional view of the surface grinding machine shown in Fig. 5; taken along the line B - B'; Figs. 8 and 9 illustrate the grinding marks which are produced on the end surfaces of workpieces; and Fig. 10 is a vertical sectional view of a wheel and a workpiece which illustrates the wheel in a condition where it has been partially worn and a protruding portion is left unground in the centre of the workpiece. Referring now to Figs. 1 to 3, which show an embodiment of the invention, the centre 0 of rotation of a cup-shaped grinding wheel 12 including its head is deviated by the necessary distance X from the centre 0 ' of the wheel so that the wheel and head is eccentric with respect to the axis of rotation 0 thereof. A plurality of chucks 14 (only one shown) are provided on rotary indexing table 27 and each chuck 14 is connected to a motor 28 provided under the index table 27 by a shaft 29. The workpiece 10 therefore rotates only about its own axis. This structural arrangement moves the grinding wheel 12 in such a manner that it follows the path as shown in Fig. 3, enabling the end surface of the workpiece to be ground without a protruding centre portion remaining unground. As is described above, with operation of the surface grinding machine constructed according to the present invention, no protruding portion remains unground at the centre of the grinding surface of a workpiece even when a grinding wheel is partially worn. Thus high working accuracy is obtained and the life of a grinding wheel is prolonged. In particular, the prolonged life of a wheel, which dispenses with the need for frequent changing of the wheel, improves working efficiency. Where technical features mentioned in any claim herein are followed by reference symbols, those reference symbols are included solely for the purpose of increasing the intellegibility of the claims.

Claims: A surface grinding machine comprising a rotary wheel support or machine head (11) for supporting a cup-shaped grinding wheel (12) which is vertically displaceable and adjustable, at least one chuck (14) carried by a support table (13,27) or bed for receiving work-pieces (10) to be ground and being disposed facing said grinding wheel (12) when located on said head (11), the or each said chuck (14) and said wheel head (11) including the wheel stock or head (11) are mounted so as to be rotatable; characterised by the feature that the grinding wheel (12) including any wheel stock or head, is mounted on the machine head (11) to extend around and eccentrically relative to the axis of rotation (0') of the rotary grinding wheel support of the machine head (11) and having a single common axis of rotation (0') with said rotary support of the wheel head. A machine as claimed in claim 1, in which said chuck (14) is rotatable about the axis ( 0 ) of the chuck holder (15,16) and the drive means includes a drive motor (21) and a planetary gear mechanism (25,26).

Inventors: NISHIO, KIYOSHI, TANAKA, ARIHISA ASAHI DIAMOND INDUSTRIAL CO. LTD.
Applicants: ASAHI DIAMOND INDUSTRIAL CO. LTD., NISSEI INDUSTRIAL CO., LTD.
Application year: 1985
Main classification: B24B7
IPC codes: B23Q1, B24B7