VIBRATORY WELDING PROCESS

PURPOSE:To improve the weld strength against separation by a method wherein welding allowance increased parts, each of which extends in the direction, in which each rib is disposed in upright, are provided at both end parts in longitudinal direction of the tip face of each rib. CONSTITUTION:A box outer 11 and a box inner 14 are respectively held by jigs 8 and 9, which are respectively fixed to the stationary surface plate and to the vibratory surface plate of a vibratory welding set so as to bring ribs 12, 22 and 32 of both the members into contact with surfaces to be welded 15, 25 and 35 under pressure by bringing the stationary surface plate near to the vibratory surface plate and to vibrate the vibratory surface plate under the state just mentioned above. As a result, the tips of the respective ribs 12, 22 and 32 and the surfaces to be welded 15, 25 and 35 contacting with the tips of the ribs 12, 22 and 32 melt by frictional heat. After the vibration of the vibratory surface plate for the predetermined period of time, the box inner 14 on the vibratory surface plate is stopped at the predetermined position with respect to the box outer 11 and the vibration is stopped and melt portions are cooled down. At that time, in the weld portion 16 at the tip of the rib 12, both end parts 16a and 16b in longitudinal direction of the rib 12 are welded with larger excess amount of melt (welding allowance) by the volume of the welding allowance increased part 12b than the amount of weld at its intermediate part 16c. A grab box 10 (not shown) is obtained by being removed from the jigs 8 and 9 after being cooled.