Patent GB-1105841-A (GB)
Title: Improvements in or relating to apparatus for cutting wire, rods or strips into precise lengths
Inventor: FITCH CLIFFORD KINGSBURY
IPC: B21F1/02
Filed: 1963-06-21
Abstract: 1,105,841. Shearing wire; straightening. WIRE PRODUCTS & MACHINE DESIGNS Ltd. 17 Sept., 1964 [21 June, 1963], No. 48406/62. Headings B3E and B3W. An apparatus for cutting wire into predetermined lengths comprises a hollow die, means for feeding the wire at a controlled rate through the die, a tool holder continuously rotatable about an axis parallel to and displaced from the axis of the die and at least one cutting tool carried by said holder so as to project therefrom whereby the tool sweeps across the face of the die, means for continuously rotating the tool-holder, and means for co-relating the rate of said feed means with the speed of rotation of the tool-holder in such a manner that all the cut pieces of wire are of a predetermined length. The apparatus includes a feed measuring device having friction rollers 12 and 13 which drive a digital rotary transducer, a rotary wire straightener 16 driven by a motor 19 through a speed regulator 18, a feed mechanism 20 driven by a motor 29 through a speed regulator 28 and a cutter mechanism 33 driven by a motor 37 through a speed regulator 36. The cutter mechanism comprises one or more cutters mounted on the periphery of a rotating cutter holder and mounted in the path of the cutters is the probe 39 of a proximity detector which generates an electrical impulse each time a cutter passes. Associated with the apparatus is a digital computer which comprises essentially an input register which receives information from the feed measuring device, a store which holds the required pin length information and a comparator which compares the information in the register with that in the store. The error between the measured length and the required length is converted into an analogue signal which controls the frequency of the cutter. Comparison is performed at cutting frequency, but if no detectable error exists the register is not cleared and the count therein is allowed to accumulate to permit higher accuracy. The Specification also refers to the use of an impulse cutter, which is not described, for cutting lengths which are outside the speed range of the apparatus and states that when such a cutter is used, the cutter is triggered when the information in the register and the store is identical. A coarse adjustment of the cutter motor speed to compensate for changes in feed speed is achieved by the use of a tacho-generator 31 which gives a voltage proportional to the feedspeed and a tacho-generator 38 which gives a voltage proportional to the cutter-motor speed. The pin length depends on the ratio of the feedspeed to the cutter-speed and this ratio is selected by a manually controlled device (65), Fig. 3 (not shown), the ratio set therein being divided into the output from the tachogenerator 31. The resultant voltage is applied through a closed loop in opposition to the voltage from the tacho-generator 38 to coarsely control the motor-speed. The impulses produced by the cutter proximity detector 53 are also fed to a divide-by-ten circuit and hence to an electro-magnetic counter. Construction of feed measuring device.-The wire passes between three grooved guide wheels 81, 82, 83, Fig. 4, through a guide tube 87, between the friction rollers 12, 13 and then through a further guide 100. The rollers 12, 13 are secured to shafts 89 mounted in blocks 91 slidable between guides 92 and connected by a tension spring 93. Also mounted on each of the shafts 89 is a sprocket 94 and a continuous chain 95 passes round both sprockets and round two coaxial sprockets 96 and 99. The sprocket 96 drives the digital rotary transducer indicating the feed speed, and the sprocket 99 runs free on the same shaft. Construction of the wire straightener, Fig. 7.- A tubular casing 104 is rotatably supported at each end by journals 105, 106 and has mounted therein four roller carriers 110 supported by trunnions accommodated by bearings in the wall of the casing so that the carriers may rotate about an axis at right-angles to the axis of the casing. Each carrier supports two waisted rollers 116, the axes of rotation of which are inclined at an angle to the axis of rotation of the carrier. The position of the rollers 116 relative to the wire is adjusted by rotating the carriers by means of a worm-wheel 117 engaged by a worm 118 mounted on a spindle which has a square end 120. The angular dispositions of the rollers 116 causes them to impart feeding movement to the wire in addition to the feed means described below. In some circumstances the feed means may be omitted and in these cases the rotational speed of the straightener is correlated with the frequency of the cutter passing the die to produce the required cut lengths of wire. Construction of feed mechanism, Fig. 8.-A frame 123 supports four grooved feed rollers 21, 22, 23, 24. The rollers 22 and 24 are rotatably mounted on spindles fixed in the frame and the rollers 21 and 23 are rotatably supported in assemblies 124; 125 which are pivotally mounted in the frame at 126 and 127 respectively and are biased by tension springs 128, 129 which tend to lift the upper rollers away from the lower rollers. The assemblies 124, 125 are pressed down by a beam 132 the position of which is adjusted by a screw and nut assembly 147, 145. To facilitate threading the wire the beam is lifted by a hand-lever 26 connected to two links 135, 138. The speed regulator 28 drives the rollers through a train of gears 150, 151, 152, 156, 167, 158, 159 and 160. Construction of cutter mechanism.- The frame 123 also supports a shaft 34 on which is mounted a disc 166, Fig. 9, formed with four dovetailsection tapered sockets 167. A shearing tool 170 is shaped on one side to engage the dovetail face 169 and is locked by a screw-operated gib 171. Each cutter is further retained by a safety plunger 176, Fig. 10 (not shown), locked by a threaded plug. The cutting edge has a curved portion 178 the radius of which is slightly greater than the radius of the wire to be cut, and the face 179 in which the groove is formed is inclined to relieve the cutting edge. The face 179a which also forms the cutting edge is inclined away from the face of the die 32 to clear the advancing end of the wire 85 after a cut. In a modification an adjustable feed strip is provided in addition to, or in place of, the computer.