GB526514A - Improvements in or relating to machine tools - Google Patents

Abstract

526,514. Hydraulically-operated grinding &c. machine tools. CINCINNATI GRINDERS, Inc. March 18, 1939, No. 8697. Convention date, March 21, 1938. [Class 60] [Also in Group XXIX] A lever 46 movable about a pivot 68 to control relative movements of machine tool parts such as the movement of a grinding-wheel relatively to the work, is moved manually a short distance to rock a link 59 about an axis 51 into a position where a spring 55 can complete the movement of the lever 46, the rate of this movement being determined by hydraulic control means. The link 59 is made of two relatively slidable parts forced apart by the spring 55, one part being pivoted to a crank pin 61 on the lever 46 so that in the position shown in Fig. 7 the line of tension 67 of the link passes to the left of the pivot 68 but when the lever 46 is rotated clockwise this line moves to the right of the pivot 68 and the compression of the spring 55 causes the link to rotate the lever further, through the crank pin 61. Fluid is admitted to a cylinder 13 to actuate a piston 14 connected to a rod 10 fixed to the tool-carrier, under the control of a servomotor device comprising a plunger 16 controlling parts in a cylinder 15, the plunger being moved in one direction by a spring 17 and in the opposite direction by a lever 18 pivoted to the rod 10 and to a rod 20 moved axially by the rotation of a grooved cam 35 rotated by the lever 46. The groove comprises three inclinations corresponding respectively to a quick movement to bring the tool up to the work, a slow movement while grinding, and a quick movement after the piston 14 reaches the end of its stroke and for the purpose of opening the valves to increase the fluid pressure so as to lock the grinder while finishing off. The movement of the lever 46 is checked by a dash-pot comprising a piston 80 working in a fluid cylinder 69 and actuated by a rod 78 connected to the lever 46. The piston has perforations and the first part of the movement of the rod 78 takes up lost motion and then closes the perforations at that end. The piston stroke comprises three parts corresponding respectively to the three stages in the inclination of the cam 35. In the first, the fluid escapes through a valve comprising a plunger 88 fitting loosely in a cylinder 86, in the second, the passage to the cylinder is closed and escape is through a passage partially obstructed by the conical end of a screw, and in the third the piston opens a valve 106 to allow the fluid to flow around the valve.