Patent GB-778219-A (GB)
Title: Apparatus for positioning a stop or other part of a machine, more particularly a machine tool
IPC: G05B19/04
Filed: 1954-06-09
Abstract: 778,219. Counting-apparatus. BERLINER MASCHINENBAU-AKT.-GES. VORM L. SCHWARTZKOPFF. June 9, 1954 [June 12, 1953], No. 16911/54. Class 106 (1). [Also in Group XXII] In means for adjusting the position of a machine part, e.g. a machine-tool slide, a stop is displaced on the machine bed by a screw rotated by an electric motor, whose number of rotations is controlled by a counting mechanism co-operating with a pre-selector, and the slide is then fed against the stop. To compensate for pitch errors in the screw, two screws 1 are used and their nuts 2 are coupled by a lever 3 having the stop 5 pivoted thereon so as to average the screw pitches. The screws are driven by gears 8 thereon and a pinion 10 rotatable through oppositely-rotating electromagnetic clutches 11, 12, respectively driven from the motor 14 directly and through reverse gear 13. One gear 8 is adjustable on its screw 1 for relative adjustment of the nuts 2, and the screws and gears are selected to move the stop 1 mm. for one rotation of the motor. The motor also drives three contacts 21, 20 19 corresponding to units of 10 mm., 1 mm. and tenths and hundredths mm. respectively, and a nut on a screw 26 driven from contact 20 gives linear displacements in units of 100 mm. The contacts and the nut are in circuit with the preselector 27, the nut sliding along a graduated contact-scale 18. Operation.-The indicators of the preselector are set according to the number of mms. and fractions thereof in the required displacement of the slide. Actuation of a push-button 41 connects the motor to the screws 1 through clutch 11, energizes the counting mechanism and starts the motor, e.g. at 3000 r.p.m. When the nut reaches a point on the contact-scale 18 corresponding to the setting of indicator k of the preselector, a relay 49 is closed to connect the indicator i to the corresponding contact of a disc 17 and when rotation of contact arm 21 closes this contact, a relay 50 is energized to reduce the motor speed to 500 r.p.m. Also, a relay 52 is actuated to connect indicator h to the corresponding contact of a disc 16 and after rotation of the contact arm 20 to close this contact, a relay 53 reduces the motor speed to 6 r.p.m. and a relay 55 connects indicators f and g to the required contacts of a disc 15. Rotation of the contact arm 19 closes its contacts and a relay 56 is actuated to de-energize clutch 11 and bring the stop 5 to rest in its set position. The slide may then be fed to bring a finger 6 thereon against the stop 5. At the same time the motor is reversed by switch 57 to drive the contact arms backwards until, when they are re-set to zero, a limit-switch 58 is operated by the nut and screw 26 to de-energize relay 56 and stop the motor. Initial actuation of pushbutton 44 energizes clutch 12 instead of clutch 11 for rotation of screws 1 in the opposite direction. The slide may carry several fingers 6 spaced 1000 mm. apart on the slide, these being brought selectively into position by the preselector to increase the range of adjustment.