GB1190294A - Improvements in or relating to Drilling Machines - Google Patents

Abstract

1,190,294. Drilling machines. DRUCKMASCHINENWERKE LEIPZIG VEB. 5 July, 1968, No. 32223/68. Headings B3B and B3C. In a drilling machine having a drilling template 12 mounted beneath a worktable 4 and an index bolt 58 mounted on the machine frame coaxially with the drill spindle, the template 12 is explored systematcially line by line by an exploring device while the worktable 4 is stationary and when a centring hole in the template is located the exploring device, together with the template and worktable, is drawn by the shortest route into alignment with the drill spindle and fixed in position by an exploring bolt 39. The worktable 4 is airfloated on a slideway 6 which extends along a cross-slide air-floated on further slideways 6 carried by side members 2 on a pedestal 1. A conduit system, Fig. 2 (not shown), applies pressure air or suction to the slideways 6 all of which are protected by cover plates 9, 10. A plate 11 forming the underside of the worktable 4 carries guides in which the template 4 is removably secured by screws 14 having tapered collars. A bridge structure 17 movable on rollers along rails 15 secured to the plate 11 has an exploring carriage 23 mounted on rollers for movement therealong. An endless flexible element 22 circulates continuously around a series of pulleys 21 one of which is coupled to a drive means. Two clamp devices 25, 27 provided on the carriage 23 for gripping the element 22 are actuated by electromagnets 24, 26 and arranged such that actuation of either one moves the carriage 23 in the appropriate direction across the bridge structure 17 and actuation of both moves the bridge structure along the rails 15. Appropriate actuation of the clamp devices 25, 27 to move the carriage line by line across the template 12 is effected by switches actuated by line-exploring pins 36, 37 which co-operate with a series of line holes along one edge of the template. The exploring bolt 39 is loaded by a spring 63 and slides in a cylindrical member 47 slidably mounted in the carriage 23 and loaded by a lighter spring 40. When the exploring bolt 39 locates one of centring holes 34 in the template 12 the cylindrical member 47 is advanced by the spring 40 so that the bolt 39 enters the hole and opening of contacts 45, 48 releases the clamp devices 25, 27 to halt the carriage 23. Associated with each centring hole 34 is an indicator hole 35 suitably positioned to receive one of four indicator pins 41 which are spaced around the bolt 39 and associated with preselector switch means whereby a hole in drilled is the workpiece only if the centring hole 34 has an indicator hole corresponding to the size of drill in use. If the preselected indicator pin 41 does not enter an indicator hole electromagnets 29 actuate levers 30 to retract the cylindrical member 47 and withdraw the bolt 39 from the centring hole 34 so that the carriage 23 resumes its movement across the template 12. Provided the pin 41 enters an indicator hole 35 contacts 49, 50 are closed so that pressure air is supplied to the slideways 6 and a slip clutch couples a rotary drive means to a pulley 52 having wound thereon a flexible cable 53 which passes through guide bushes 54, 56 to the carriage 23 and is maintained at a predetermined minimum tension by a weight 53<SP>11</SP>. Rotation of the pulley 52 draws the carriage 23 together with the template 12 and worktable 4 into a position wherein the point of attachment of the cable 53 is vertically above the guide bushes 54, 56 so that the exploring bolt 39 is aligned with the index bolt 58 and the upper guide bush 56 is free to move upwardly under resilient loading to actuate switch means which interrupts the supply of air to the slideways 6 and pressurizes an hydraulic cylinder 61 to raise the index bolt 58. A conical end 59 on the index bolt is urged into a conical hole in the cylindrical member 47 so that the exploring bolt is pressed into the centring hole 34 by the spring 63 and a closure member 44 on the member 47 firmly clamps the template 12. A time-delay relay then applies suction to the slideways 6 to inhibit movement of the worktable and drilling or reaming of the workpiece is either initiated automatically or a signal is given to the machine operator that drilling can commence.