Patent GB-1044894-A (GB)
Title: Improvements in or relating to bonding of materials
Inventor: TOMSON ERIC
IPC: B29C65/00
Filed: 1964-04-24
Abstract: 1,044,894. Seaming non-metallic sheet material. OMEGA LABORATORIES Ltd. April 26, 1965 [April 24, 1964], No. 17215/64. Heading B5K.. Materials 6 at least one of which is wholly or partly thermoplastic are bonded together by feeding the materials 6 through a bonding head 3, 4, supplying ultrasonic power to the head 3, 4, and controlling the supply of ultrasonic power to the head 3, 4 in accordance with the feeding rate so as to provide the same amount of power for each individual " stitch." Bonding in the form of " stitches " denotes bonding consisting of a plurality of individual bonds which may be separated from each other longitudinally or may make up a seam by overlapping the ends of the individual bonds- In one embodiment, Fig. 1, ultrasonic electrical energy is supplied by an ultrasonic generator 1 comprising an oscillator and an amplifier to a magnetostrictive transducer 2 which converts the electrical energy into mechanical vibrations which are transmitted to a probe 3. An anvil 4 is mounted to move towards and away from the probe 3 and is urged towards the probe 3 by a spring when it is in compression, this compression being controlled by a motor 8 through a linkage 12, e.g. an eccentric and rod mechanism. The material 6 is fed by a transport mechanism 7 of the type used in standard needle sewing machines and which is driven by the motor 8 through a linkage 9, e.g. an eccentric and rod mechanism. The speed of the motor 8 is controlled through a variable resistance 10 operated by a foot pedal 11. The linkages 9, 10 are arranged so that when the material 6 is stationary, i.e. during the return stroke of the mechanism 7, the spring 5 is compressed to urge the anvil 4 against the probe 3. A switch 14 operable in response to movement of the anvil 4 controls a control and timing device 15 which controls the generator 1 and provides, in certain circumstances, a bias for the transducer by way of a line 16. The device 15 meters the energy supply, e.g. by acting purely as a timing device and triggering the oscillator for a certain length of time, the generator power remaining constant. Alternatively, the time of operation of the oscillator could vary depending on the timing of the stitching and the power could be varied to match. Also, it can operate to bias back the transducer and thus control the power and cut-off the ultrasonic vibrations. In a second embodiment, Figs. 4 and 5 (both not shown), a motor 55 is mounted beneath a table top 51 and may be controlled by a foot pedal. A rod 72 provided with an arbor 73 to co-operate with an ultrasonic probe 74 is reciprocated by the shaft 57 of the motor 55 through a pulley 56, a belt 58, reduction pulley gearing 60, a belt 59, a pulley 61, a shaft 62, a universal joint 66, a shaft 67, a universal joint 68, a shaft 69, and a variable eccentric 70. A tension spring 75 acts on the eccentric 70 through a rod 76 so that the arbor 73 presses on the probe 74 with a predetermined pressure which is adjustable by moving the eccentric 70 by a knob 79. The pressure of afoot 80 which co-operates with the arbor 73 is adjustable by a knob 81 which alters the compression of a spring 82. Movement of a lever 84 rotates a cam 85 to lift the reciprocating mechanism away from the workpiece. The probe 74 is formed as the end of a horn on a velocity transformer 88. A lower transformer 89 is mounted directly on a transducer 90 in an oilfilled casing 91 in an outer casing 92. Cool air is circulated between the casings 91, 92 by a blower 94. The feed mechanism 100 for the workpiece comprises a toothed member 102 on a member 103 attached to bell-crank levers 104, 105 operated by arms 106, 107 reciprocated by a double eccentric arrangement 108 driven by a shaft 109 driven by a toothed belt 65 so that the member 102 executes a substantially rectangular movement. A cam 112 on the shaft 109 operates a switch 114 to provide power for the probe 74 when the arbor 73 is in its lowermost position.