Patent GB-750334-A (GB)
Title: Improvements in or relating to method and machine for moving work past a tool, especially for joining pieces of material
IPC: D01D5/06
Filed: 1953-08-05
Abstract: 750,334. Sewing-machines. SELBY SHOE CO. Aug. 5, 1953 [Nov. 26, 1952], No. 21599/53. Class 112. [Also in Groups VIII and XXXVIII] A method of moving work past a tool in accordance with a predetermined pattern comprises the steps of drawing the pattern to scale with respect to a pair of co-ordinate axes; preparing two information carriers, such as electrically conductive lines, each of said carriers relating the respective distances from one of said co-ordinate axes to a plurality of points on the pattern with the corresponding curvilinear distances along the pattern from a reference point thereon; and employing said carriers to govern relative movement between the tool and the work. The Specification describes the stitching of a pattern upon a shoe upper. It is stated that the invention is also particularly applicable to staples, heat and pressure sealing devices, and other similar machines in which it is desirable to move the work past the tool at a controlled rate, as well as in accordance with a predetermined pattern. Fig. 5 shows a pattern 156, and Figs. 6 and 7 show the two information carriers, in the form of guide curves 157 and 158, which are derived from the pattern. The abscissa of each point on the curve 157 is equal to the ordinate AY of the corresponding point A on the pattern, and the ordinate of said point on curve 157 is equal to the distance AS along the pattern from the datum point O to the point A. Similarly, the abscissa of the corresponding point on curve 158 is equal to the abscissa AX of point A, and the ordinate is equal to the distance AS. The work is secured by clamps 106, Fig. 4, to a rectangular frame 11 disposed beneath the needle of a sewing-machine 20, the frame being mounted for independent movement along a pair of rods 108 and 115 disposed at right-angles to each other. Guide curves 33, 34 are drawn upon a strip of paper 147 driven linearly by a rotary drum 151. Tracing points 36, 36a are arranged to follow the respective curves by movement parallel to the axis of the drum, movement of point 36 being transmitted to cause equal movement of frame 11 along rod 115, and movement of point 36a causing equal movement of frame 11 along rod 108; whereby the line of stitching reproduces the pattern from which the guide curves were derived. The sewing- machine is mounted on a base 104. A sleeve 107, carried by one edge of frame 11, slides upon rod 108, the opposite edge of the frame being provided with rollers which ride upon the base 104. A transverse edge of the frame carries a pair of spaced arms 145 connected by a rod 144 upon which is slidably mounted a block 143, the latter being slidable upon a rod 146 which is mounted on the base 104 parallel to rod 108. The latter is fixed at one end to a sleeve 112 slidable on rod 115, the latter being carried by the base 104. The other end of rod 108 is provided with a roller 113 disposed in a channel member 114 secured to base 104. The strip of paper 147 has perforated edges engaged by teeth 150 provided at the ends of the drum 151, the latter being rotated by means of a gear 152, a gear-box 153 and a flexible coupling 154 from the main spindle of the sewing-machine. Print 36 is carried by a block 118 slidably mounted on a rod 120 secured to an arm 121 which overhangs drum 151. Block 118 and sleeve 112 are interconnected by a cable 24a driven by a reversible motor 21a, whereby point 36 follows curve 34 and sleeve 112 is moved correspondingly along rod 115. Point 36a is carried by a block 132 slidable on a rod 133, blocks 132 and 143 being interconnected by a cable 131 driven by a reversible motor 128, whereby point 36a follows curve 34 and block 143 is moved correspondingly along rod 146. The control circuit for one of the reversible motors is shown in Fig. 2. The guide curve 33, which is drawn in graphite or a conductive ink, is earthed at 76. The tracing point 36 is connected through a source of bias voltage 73 to the grid 71 of a double triode thermionic valve 47. The anode 65 associated with grid 71 is connected by a lead 45 to one end of the coil 44 of a relay 43, and the cathode 66 associated with grid 71 is connected by a lead 62 to the secondary winding of a transformer 50. The second anode 56 is connected by a lead 55 to the opposite end of said winding, and the second cathode 58 is connected by a lead 46 to the opposite end of coil 44. The arm 77 of the relay, when the coil is not energized, rests against a contact 80 connected by a lead 87 to terminals 88, 90 of a reversing switch 85. Arm 77, when coil 43 is energized, bears against a contact 78 connected by a lead 82 to the terminals 83, 84 of switch 85. The pivoted end of arm 77 is connected by a lead 91 to a power lead 52. A power lead 53 is connected by a lead 92 to the field coils 41, 42 of the reversible motor 21a, the opposite ends of the field coils being respectively connected by leads 93 and 94 to the middle terminals 95, 96 of switch 85. When point 36 makes contact with line 33, bias is applied to grid 71 to prevent flow of current through coil 44. With the handle 103 of switch 85 to the right, field coil 41 is energized and the motor will move the point to the left. Assuming handle 103 to be towards the right and the point initially in contact with the line, movement of the point will break contact with the line to remove the bias from grid 71. Coil 44 will then be energized to bring arm 77 against contact 78, thereby energizing coil 42 to reverse the motor for moving the point to the right. The point will thereby maintain contact with the left-hand side of the moving line. If handle 103 is moved to the left, the point will maintain contact with the right-hand side of the line. Cables 24a and 131 are employed as electrical conductors between the lines 33, 34 and the thermionic tubes which are mounted in the base 104. It is stated that the line follower may be of any other suitable type, e.g. photo-electric.