Patent GB-221890-A (GB)
Title: Improvements in and relating to electric welding
IPC: B23K9/025
Filed: 1923-06-23
Abstract: 221,890. Marks, E. C. R., (Pabst Co., F.). June 23, 1923. Uniting by fusion.-In an electric welding machine, particularly for welding the longitudinal seams of a series of axially aligned tubes, the work is mounted in a carriage traversed by a motor, the motor circuit and the driving connection between the motor and the carriage being automatically disconnected by the carriage. A series of tubes 40 are secured by clamps 70 on a wheeled carriage 24 which is traversed by a rack and pinion 35, Fig. 6, on a shaft 34 driven by friction gear 33, 32 from a shaft 31 rotated by worm gear from a motor 26. A series of pairs of clamps are secured to a pair of parallel tubes 72 on the carriage, the tubes being rocked by a piston operated by compressed air. The clamps on one tube are carried by brackets adjustable on and secured by bolts to the tube, whereas the clamps on the other tube are carried by brackets rotatably mounted on the tube and adjusted by screws 93 carried by brackets 99 fixed by bolts to the tube. Compressed air is first admitted to the cylinder so as to tighten the clamps slightly on the tube 40, the seams are then aligned at the junction of successive tubes by guides 95, Fig. 13, on rotatable and vertically adjustable arms 96 mounted on the carriage. Full pressure of air is then supplied to clamp the tubes in the carriage and the arms then elevated and swung out of the way. The metal electrode 43 is secured in a clamp 102 on the insulated end of an overhanging arm 101, Fig. 17, carried by a support 46, Fig. 1, which is vertically adjusted by a rack 48 and pinion 50, Fig. 6, on a shaft 51 driven by friction gear 52, 53 from the shaft 31. The electrode clamp consists of a pair of jaws 103, 104, Fig. 17, non-rotatably mounted in a casing 106, which is rotated upwardly by a handle 117 when the jaws are to be opened and is returned either by hand or by a spring into contact with a stop when the jaws are to be closed. The casing is closed by plugs 107 and between one plug and the slidable jaw 104 is inserted a diaphragm 108 and a perforated flanged ring 109 to form a chamber 111, which, in the position shown, is open to compressed air passing through tubes 114, 113 and passages 119, 120 so as to clamp the electrode. On rotating the casing upwards the passage 120 is put out of alignment with the passage 119 and air is exhausted from the chamber through exhaust ports so as to free the jaws. In order to oppose the tendency of the support 46 to move downwardly due to the weight of the parts, the support passes through a casing 189, Fig. 18, secured to the casing 47, Fig. 6, the casing 189 having a conical end 192 engaged by a series of spring-pressed members 191 forming together a conical annulus. A water or air-cooled member is positioned in the tube under the electrode to cool the weld. This member consists of a conically-bored head rotatably adjustable on and secured by a screw to the conical end of a tube 181, which is pivoted to a bracket 183 and passes through a spring- pressed block 185 adjusted by screws 187, 188. The cooling fluid circulates either from an inlet 181<1> through the head and back by a concentric tube to an outlet 183<1> or vice-versa. Current from an alternator 200, Fig. 2, is connected to the electrode through main-switch 202, welding- switch 142, adjustable reactance 213 and wire 204, the welding circuit being completed from the work 40 and framing 20 through switch 142. The motor circuit is in parallel therewith through wire 214, switch 143, overload and underload electromagnetic circuit breaker 165, motor 211, controller 210, and framing 20. The speed of the motor is thus controlled by the arc to keep the length of the arc constant. The electrode is passed through an insulating guide 125 and the lower end brought adjacent the work. The switch 142 is then put in, the electrode brought into contact with the work and then raised to strike the arc and the motor switch 143 put in, and the friction drive then engaged as described below. When the carriage reaches the desired position an adjustable stop 130 thereon engages a pin 132 on a spring-controlled lever 131 so as to push down a rod 134, Fig. 8, connected thereto and thus move arms 135, 141 on the pivot 136 so as to disengage a hook 156 from the shoulder 160 on the pivoted armature 161. This hook is pivoted to a casing 157 sliding on a bar 138 and connected by a rod 155, Fig. 6, to one arm of an elbow lever 150, 151, which is mounted on a sleeve 147 rotatable on a shaft 56 and which is normally under control of a spring 153 tending to open the switch 142. The switch is connected by a rod 144 and arm 145 to a collar 146 fixed also to the sleeve 147. Disengagement of the hook thus allows the spring 153 to open the switch. The motor switch 143 is connected by a rod 144<1> to an arm 145<1> secured to the shaft 56. The sleeve 147 has a handle 158, and the shaft 56 a handle 63, which are connected together by bevelled pins 159', 159, Fig. 21, so that counterclockwise rotation of the sleeve 147 also rotates the shaft 56 to open the switch 143 and release the friction gear. The pin 159' is spring-pressed and has a lateral pin 216 which engages a cam on the framing so as to withdraw the pin 159<1> and thus allow the handle 63 to close the motor switch and put in the friction gear when the welding switch is open. The motor switch may be opened independently of the welding switch. The shaft 56 has a cam wheel 58 engaging a cam 60 on a spring-pressed beam 61 fixed to the shafts 34, 51 so that when the switches are opened the shafts are drawn back to release the friction wheels. The shafts 34, 51 may be rotated by hand wheels 55, 65 for starting or adjustment purposes, either when the friction gear and motor are in operation or when the friction gear has been withdrawn by rotating the handle 63. Should the motor current be too small, the armature 161, Fig. 8, is moved by the spring 153 and hook away from the electromagnet to disengage the hook and stop the machine. Should the motor current be too largea pivoted armature 166 is drawn towards theelectromagnet and a pin 170 thereon releases thehook and stops the machine. The armature 166 has an extension containing a spring which presses a pin 172 against the armature 161. The spring is adjustable by a screw to vary the overload.