Patent GB-660416-A (GB)
Title: Automatic control mechanism, particularly for moving machine parts
IPC: B23Q15/00
Filed: 1949-05-10
Abstract: 660,416. Actuating machines. BERTHIEZ, C. W. May 10, 1949 [May 12, 1948], No. 12441/49. Class 83 (iii). [Also in Group XXXVII] A control device, particularly for arresting the feed of a machine-tool table, comprises a control member 3 which has at least one projection 6 and is movable with respect to a second member having a slot 7 partially obstructed by resilient means 12 on the side opposed to the control member and a movable element, such as a ball 8, which, when the control member is moved in one direction, is moved by the projection 6 through the unobstructed part of the slot to operate control means, such as a switch 20, and when its control member is moved in the opposite direction, is driven along the slot to a position in which it does not engage the control means. The control member may be a sliding rod 3, Fig. 1, having an annular rib 6, or a rotary shaft 14, Fig. 3, having a projection 15, and the slot 7 is partially closed by a leaf-spring 12 or 12<SP>1</SP>. On downward .movement of the piston or anti-clockwise movement of the shaft, the rib 6 or projection 15 moves the ball out to engage a stud 9 on a leafspring 10 and by means of a plunger 16 operates a switch 20 once, the spring 12 or 12<SP>1 </SP>returning the ball into the recess behind the projection. On the return stroke, the projection forces the ball to the other end of the slot and then outwards against the spring, but without operating the switch. As applied to controlling the movement of a table 24 of a boring and 'milling machine, a pair of spring-loaded control rods 68 and 134, each having three annular ribs are mounted one above the other in a switch-box 55 secured to a bracket 48 on the machine bed. The upper rod 134 controls the speed of the table at any required position through conical-headed dogs 40 placed in a groove 36 in a U-shaped member 28 attached to the table and the lower rod 68 controls the stopping of the table through similar dogs 41 or abutments 148 fitted in another groove 37. The dogs are of three different heights so that, for speed controlling, the smallest size will move the rod 134 only sufficiently to operate the ball 144 controlling the switch 141, the medium size will operate first the switch 141 and then the switch 139 and the largest size will operate switches 141, 139 and then the switch 140, the switches being connected to any known type of speed control system. The final switch 140 is operated by a ball 143 in a cylindrical hole instead of a slot, since it is only operative at the end of a stroke. The rod 68 is similarly operated by the dogs 41, the first switch 90 slowing down the speed in a direct drive, then the switch 91 decreasing speed in a reduction-gear drive so that the table is moving at minimum speed when a stop switch 102 is finally operated; the switch 90 may be short-circuited when the direct drive is not used. When it is desired to stop the table with greater accuracy than can be given by the conical dogs acting on the spherical end of the rod 68 and when it is not necessary for the table to move again in the same direction, the adjustable abutment 148 may be fitted in the groove 37. This abutment, according to the direction of movement of the table, engages one or other of two pistons 128, 129 having ends 126 sloped at the same angle as the heads of the dogs and engaging a ballbearing ring on a pin 124, thus causing the rod 68 to operate the switches 90, 91 to slow down the table. Just before the stop switch 102 is operated, a second stop switch 97 or 133 is directly operated by a pin 131 on one or other -piston. Accurate gauge blocks or a micrometer 151. held by a leaf-spring 152 may be fitted in front of the abutment 148 to provide for accurate initial adjustment of the stopping- point. The final position of test of the table can be determined roughly by an adjustable index 59 on the switch-box and a scale 34 on the table or more accurately by a comparator 113 which indicates the amount of movement of the rod 68 by means of bevelled surfaces 68a acting on a ball 122.