Patent GB-1161800-A (GB)
Title: Improvements in Bonding Metal Parts Involving their Rubbing Contact.
IPC: B23K20/12
Filed: 1966-10-07
Abstract: 1,161,800. Welding by pressure. CATERPILLAR TRACTOR CO. 7 Oct., 1966 [21 Oct., 1965], No. 45041/66. Heading B3R. In bonding metal parts together the parts are engaged in relative reciprocatory rubbing contact across a common interface to render the surfaces in contact plastic and as the reciprocatory motion ends sufficient pressure is applied to the parts to squeeze flash from the interface. A machine for bonding the parts comprises a frame 22, drive means 23 for reciprocating one workpiece WP1, a fixture 24 for holding the other workpiece WP2, loading means 26 for pressing the pieces together and balance means 27 for dynamically balancing the motion of the drive means. The drive means includes a motor 28 on a plate 31 both of which are able to be moved upwardly by a lever to disconnect the drive. The motor output shaft is connected by pulleys and a belt 41 to drive a shaft 37 mounted in bearings on the frame 22, the shaft 37 carrying a brake disc engageable by brake blocks to stop its rotation. An eccentric journal keyed to the shaft 37 is encircled by a bearing in the inner end of a connecting rod 54 connected at its outer end to a block 50 in which the workpiece WPI is secured. A balance arm 27 is mounted on another eccentric journal on the shaft 37, 180 degrees out of phase with the first journal and the outer end of the arm 27 is connected to the frame 22 by springs. The block 50 is mounted on the fixture 24 by balls in V grooves and a vertically movable block 68 is provided in the fixture 24 to carry the workpiece WP2. A lever 72 pivoted to the frame 22 at 73 engages a block 77 on the block 68 and carries a weight 78 to provide heating cycle pressure and a weight 97 for an increased pressure. The weight 97 is carried on a rod 81 kept spaced from the lever 72 by a pin operated by a solenoid 83. Inert gas supply tubes 88, 89 are provided. In operation with the workpieces in their blocks the motor rotates the shaft 37 and reciprocates the piece WP1 with the lever 72 initially out of engagement with the block 68. After a short wear-in period during which the gas flow is started and the parts are rubbed under the load of the block 68 the lever applies the load of the weight 78 and when the surfaces have been heated to plastic condition the motor is deenergized, the motor is lifted to disconnect the motor from the shaft 37, the brake is operated and the solenoid 83 energized to apply weight 97 to squeeze out plastic material as a flash from the workpieces. Rectangular section mild steel parts 1 inch by “ inch are bonded with a heating pressure of 8400 p.s.i. for 5 seconds after a wear-in of 2 or 3 seconds. The pressure is increased to 22,000 p.s.i. at the end of the cycle. In a modified apparatus the motor 28 is slidably mounted, is normally biased by a spring to a position in which tension is exerted on the drive belt and is slidably from this position by a piston and cylinder device to disconnect the drive. The load applying means employs a pneumatic piston and cylinder device instead of weights and the brake is actuated by a solenoid. The motor moving cylinder, the load applying cylinder and the braking solenoid are controlled by a timer device but can be actuated manually. In a further modification the balance arm is coupled to another identical fixture so that two bonds are performed simultaneously.