Patent GB-943850-A (GB)
Title: Improvements in or relating to positioning devices
Inventor: SMEETS GERARD GASTON FRANS
IPC: B23Q17/22
Filed: 1961-05-25
Abstract: 943,850. Drilling machine details. PROVINCIAL ENGINEERING Ltd. May 25, 1961, No. 18971/61. Heading B3C. [Also in Divisions B4 and G1] A drilling &c. machine positioning device comprises means for setting a tool slide approximately in a required position and separate means for adjusting the tool holder accurately. A frame 1 and 4 slidably supports a tool slide 2 which is movable by a lead screw 5 rotatable by a wheel 6. A tool post 21 is secured to slide 2 and a bush 22 is provided to guide a drill or marker so that a workpiece W supported on a table 34 can be scribed or drilled. Lead screw 5 is rotatably and slidably journalled at each end in frame 1 and rotatably carries a gear-wheel 10 which is adapted to rotate with screw 5 when a ratchet 12, 13 is engaged. An axially fixed shaft 15 having a gear 11 secured thereto, is rotated by screw 5, and a graduated drum 18 keyed to shaft 15 is slidable on and rotatable with the shaft. Drum 18 is moved along shaft 15 by slide 2 whose sides 36 extend over the drum, and shaft 15 can be rotated relative to screw 5 by locking the latter with a member 9 and rotating a knob 19 secured to the shaft. A micrometer head 20 on screw 5 provides small accurate axial adjustments to screw 5 and a graduated scale 24 extending over rollers 29, 30, 35, 32, cooperating with drum 18 provides the means for setting the approximate position of slide 2. Scale 24 comprises indices and also two sets of windows 27, 27<SP>1</SP> etc.; 28, 28<SP>1</SP> &c., and drum 18 has two helical scales 1-64, so that on rotation of the drum in one direction, one of the scales will be read through windows 27 &c. and in the opposite direction the other scale will be read through windows 28 &c. If lead screw has a pitch of # inch, and gears 10, 11 are of the same size, each complete turn of screw 5 will displace slide 2, # inch, e.g. to the right, and an indication of <SP>8</SP>/ 64 inch will be read through window 27 after first setting scale 24 and drum 18 to read zero. Slide 2 may be de-coupled from lead screw 5 to allow greater adjustment and gears 10, 11 and shaft 15 may be replaced by a belt running over lead screw 5 and a short shaft in place of shaft 15 and the belt may itself carry graduations. Micrometer head 20 comprises a nut 38 which engages the screw thread on lead screw 5, a bearing 37 movable in frame 1 and adapted to be clamped by a screw 33 and a sleeve 40 rotatably held on nut 38 by a ring 49 and graduated collars 41, 44 rotatable relative to each other to set the micrometer head for subsequent axial adjustment of screw 5. Bearing 37 has a slot 46 which co-operates with a key 47 on nut 38, so that with the bearing clamped, rotation of nut 38 will move screw 5, and therefore tool slide 2, axially. In operation, to drill holes C, B, in a workpiece prior to bending the latter, Fig. 6, the following formula is used. A#B = Ia and Ib-0.43R and BA wherein R is the radius of the bend, BA is the bend allowance for material having a thickness T and in this instance BA=<SP>20</SP>/ 1000 and T=<SP>50</SP>/ 1000 and R=O. The collars 41-44 on micrometer head 20 are set in the following manner. Index 52 on collar 41 is set at <SP>50</SP>/ 1000 from index 55, index 51 on collar 44 is set at <SP>50</SP>/ 1000 from index 50, and collars 43, 44 are rotated together until indexes 50, 55 are displaced <SP>20</SP>/ 1000 . The drill is set at point A on the work, and tape 24 and drum 18 are set to zero. Wheel 6 is rotated until distance Ia is read on indicator 24, 18 and is then locked by detent 9 and tape 24 and drum 18 are set to zero. Detent 9 is removed and distance Ib is cranked up on indicator 24, 18. Collars 44-44 on micrometer 20 are rotated as a unit until finger 56 on frame 1 is astride index 55, and nut 38 is rotated until finger 56 is astride index 50, thus moving lead screw 5 and the drill <SP>20</SP>/ 1000  inch axially to cater for the bend allowance, and the hole B is drilled. In drilling holes B, C, the inside dimensions Ia, Ib, or the outside dimensions Oa, Oc may be used for setting the approximate position, and the necessary allowances for bend, thickness of material &c. is met by micrometer head 20, and any combination of collars and scales may be used.