Turning – Severing or cut-off – Interrelated means for tool infeed and circumrotation
Patent
1983-03-15
1985-11-12
Husar, Francis S.
Turning
Severing or cut-off
Interrelated means for tool infeed and circumrotation
82 19, B23B 2100, B23B 328
Patent
active
045520453
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a positioning device adapted to position a workpiece, a tool or the like on a lathe or other machine for machining a revolving workpiece with a tool. The positioning device provided by this invention ensures, among other things, a high positioning accuracy and an improved machining efficiency.
BACKGROUND ART
With the increasing demand for precision-machined parts, a variety of positioning devices have recently been developed and put to use to meet the demand. A conventional positioning device will first be explained with reference to FIGS. 1 and 2 which illustrate a cam-type lathe incorporating the device. A headstock 1 includes a main spindle 2 fitted with a chuck 3 adapted to rotate a workpiece 4. A tool 5 is secured by a tool holder 6 and a tool mount 7 to a table 9 adapted to move in opposite X-directions. Table 9 and a table 10, adapted to move in opposite Y-directions, are driven respectively by cams 13 and 14 through links 11 and 12. A stop 15 is provided to limit the position of the table 10.
As illustrated in FIG. 2 table 9 and table 10 are each so designed that a movable section 16 thereof shifts along a guide 17. Because the sliding movement of the movable section 16 of the table relative to the guide 17 must be suitably accurate, it is common practice to interpose contrivances such as a sliding member 18 and a screw 19 associated therewith to apply a preliminary pressure as shown in FIG. 2. However, if a preliminary pressure is applied to the sliding member 18, a large frictional force is generated between the guide 17 and the movable section 16 of the table to cause a "stick slip" which leads to decreased accuracy.
Moreover, when the stop 15 is utilized to limit the position of table 10, the stop is caused to undego elastic deformation by the force acting thereon from the table 10, and this means that the force with which table 10 abuts the stop 15 must be constant in order to maintain constant the amount of elastic deformation. Thus, the friction force generated between the movable section 16 and the guide 17 influences the magnitude of forces with which the table 10 contacts the stop 15, with the result that positioning accuracy is adversely affected.
It may be contemplated to employ balls or rollers in lieu of sliding member 18 to reduce the friction force by way of a rolling mechanism, but such an arrangement has been found to be of little practical value for achieving high-precision positioning because of dimensional variation of the balls or rollers.
SUMMARY OF THE INVENTION
This invention relates to a positioning device comprising an X-direction carriage or slide table and a Y-direction cross slide or slide table which are slidable in two directions perpendicular to each other, stops which delimit accurate stop positions for the slide tables, cams and levers for shifting the slide tables, biasing the means for biasing the two slide tables toward the stops and linear drive means for shifting at least one of the two slide tables over a predetermined distance against the respective biassing means. In accordanace with this invention, the two slide tables are accurately positioned by the cams and levers in association with the stops, and when a replacement of the workpiece on the tables or of the tool is necessary, the slide tables are shifted by the linear drive means from a machining position to a position that permits easy replacement, whereby high-precision positioning over a long period of time can be assured.
BRIEF DESCRITPION OF THE DRAWINGS
FIG. 1 is a schematic plan view showing the conventional cam-type lathe;
FIG. 2 is a cross-sectional view taken along the line AA' of FIG. 1;
FIG. 3 is a plan view showing a lathe as an embodiment of this invention;
FIG. 4 is a front view in partial section of the lathe of FIG. 4;
FIG. 5 is a side-elevation view in partial section of such lathe;
FIG. 6 is a front view in section of the headstock thereof;
FIG. 7 is a cross-sectional view of such headstock taken along the line BB' of FIG. 6;
FIG. 8
REFERENCES:
patent: 2663977 (1953-12-01), Gerard et al.
patent: 2934812 (1960-05-01), Allen
patent: 3492897 (1970-02-01), Cunningham et al.
patent: 3708923 (1973-01-01), Youden
patent: 3946471 (1976-03-01), Link
Hara Shoji
Hasegawa Morimichi
Imanishi Kiyokazu
Inoue Mamoru
Husar Francis S.
Matsushita Electric - Industrial Co., Ltd.
Terrell William E.
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