Patent GB-1036701-A (GB)
Title: Apparatus for controlling the course of an operating member
IPC: B43L13/02
Filed: 1961-04-18
Abstract: 1,036,701. Machine tool details &c. J. I. SCHAPIRO. July 17, 1962 [April 18, 1961], No. 13867/61. Headings B3B and B3K. [Also in Divisions B6 and G1] Apparatus for controlling the course of an operating member, e.g. a stylus or tool for drawing, tracing, plotting, engraving, or end milling comprises a support member, a plurality of guide pairs, each defined by a guided member supported for movement by a guiding member and including a rotary guide pair 207A, 207B, and a linear or radius guide pair 206A, 206B, which guide pairs are connected in series in the sense of the guided member of the rotary pair being connected to the guiding member of the linear pair, the guiding member of the rotary pair being connected to the support member and the guided member of the linear pair being connected to the operating member, further guide pairs connected to constrain the operating member for two dimensional movement, and in respect of each of said guide pairs, a means for locking the guiding and guided members thereof against relative movement, said locking means being normally in the locked condition, and means for selectively releasing the respective locking means. In the apparatus shown in Fig 1, the further guide pairs comprise a rail 205B supporting a carriage 205A slidable thereon and a rail 204A slidable in a guide 204B which is integral with the carriage 205A. Thus by locking the rail 204A to the guide 204B or the carriage 205A to the rail 205B the operating member, in this case a stylus 201, can be made to draw straight lines parallel to (AK) and at right angles to (AD) the rail 205B respectively by movement of the stylus above a drawing board 201 by an operator using a handle 216. The rotary and linear guide pairs form a compass mechanism mounted on a rail 209B on which a carriage 209A supporting the rotary guide pair 207A, 207B is slidable. The member 207A carries the member 206A which is in the form of a rail and which supports the member 206B. The member 206B is pivotally connected by a rotary guide pair 210 to a carriage 208A slidable on a rail 208B integral with the rail 204A. The position of the member 206B on the rail 206A determines the radius of a circle (B) which can be drawn by the stylus 201 if the rotary guide pair and the guide pairs 204, 205 are not locked. The position of the centre (C) of the circle is determined by the positions of the carriages 209A, 208A on their respective rails 209B, 208B. By locking the guide pairs 209 and 207 the stylus will draw a radius (AC) of the circle B. If the guide pair 207 is now unlocked and the guide pair 205 locked the stylus can be moved along the line AH when locking and unlocking of the pairs 207, 205 will enable a further radius CH to be drawn. Various arrangements for locking and unlocking certain or all of the guide pairs by use of multi-position switches 214, 215 on the handle 216 using an electrical control circuit are described in the Specification. The locking means used is shown at 104, Fig. 8, of the Provisional drawings, and comprises pivoted levers mounted on the particular carriage, which normally grip the associated rail, the levers being held by a spring (not shown) in this position and an electromagnet which when energized pivots the levers to release their grip on the rail. In the case of the rotary guide pair 207 the locking means comprises an electromagnetically actuated clutch mechanism. Fig. 4 shows a similar arrangement to that shown in Fig. 1, but the size of the compass mechanism is minimized by the use of a pantograph arrangement 225 the small scale end of the pantograph being pivotally connected by pin 223 to the carriage 208A and the large scale end of the pantograph carrying the stylus 201. The pin 223 may be positioned at any point within a rectangle 227 and thus the stylus may correspondingly be positioned within a rectangle 226 which is conveniently the size of the drawing board 203. The whole mechanism except the pantograph is mounted below the drawing board, the pin 223 projecting through a hole in the board 203, on a ring bearing 221 so that it may be rotated relative to a drawing board for drawing oblique lines. A clamp screw 228 is provided to hold the mechanism in its adjusted position. In the apparatus shown in Figs. 2, 3, 5 and 8 of the Provisional drawings the stylus 10 is mounted on a head 6 for movement over a drawing board 1, and the stylus may be raised by raising a handle 15 or lowered when it is desired to draw on the board 1. The head 6 is secured to two rails 3 which can slide on a carriage 4 in a direction at right angles to rails 38, 39 on which the carriage 4 is itself slidable. Locking means are again provided so that the stylus may be made to draw straight lines parallel to and at right angles to the rails 3. A cord 124 passes round pulleys 123, 125 at the ends of the rails 3 and is secured to the carriage 4, the pulley 123 rotating a scale 50 on the head 6 so that the distance travelled by the stylus 10 over the board 1 parallel to the rails 3 may be indicated. An endless cord 61, Fig. 5, also passes round pulleys 62 to 71 to rotate a scale 60 to indicate the distance travel by the stylus parallel to the rails 38, 39. A compass mechanism is also provided (see Fig. 8) and comprises a rotary guide pair 96 pivotable about a point 94 on a carriage 95 slidable on rails 97. The rails 97 are secured at one end to a carriage 99 slidable on a rail 100 and are secured at their other end to a rail 102 slidable in bearings 103. The point 94 can be positioned at any point inside a rectangle 105, Figs. 3, 8 and may be held at that point by locking means associated with the carriages and rails described. The rotary guide pair 96 carries a radius arm 91 in the form of two rails 92 and a carriage 112 is slidable on these rails to determine the radius of a circle to be drawn by the apparatus. The carriage 112 itself supports two rails 113 on which a further carriage 115 is slidable, and this carriage is pivotally connected by a pin 88 to the small scale end of a pantograph 80, 81, 82, 83, 84. Fig. 3. The member 81 of the pantograph is pivotally secured at 85 to the frame of the apparatus and its large scale end is secured at 87 to one end of the rails 3. Thus by rotation of the radius arm 91 the stylus 10 is constrained to move in a circle on the board 1. Then by locking the rotary guide pair and unlocking the carriage 115 on the rails 113 a tangent to the circle at the locked position of the arm 91, can be drawn. Cords 131, 127, 124 are provided to indicate the angular position of the arm 91 on a protractor scale 120 on the head 6. The board 1 is mounted for rotation through 45 degrees to either side about a pin 140, Fig. 3, to allow oblique lines to be drawn on the board 1, the angle of the board being indicated by a pointer 142 and scale 141.