China's machinery manufacturing industry is in an industrial state of transformation and development. The industry's technical level is developing rapidly, production concentration is high, and market access is very large. Our company has advanced machinery manufacturing technology, a group of outstanding machinery manufacturing R&D personnel and perfect standardized quality supervision and management, and is committed to the globalization, networking, automation and green development of the machinery manufacturing industry. A sprocket is a wheel with cog-style sprocket teeth that engages the exact pitch blocks on the link link or cable. Sprockets are widely used in chemical, textile machinery, escalators, wood processing, three-dimensional parking garages, agricultural machinery, food processing, instrumentation, mechanical transmission in petroleum and other industries. When the sprockets used by the existing ships are damaged, the damaged parts are often welded and repaired by welding. During the welding process, a welding platform is required. The existing welding platform is not convenient for various chains with different inner diameters. The sprocket is fixed, and the sprocket cannot be positioned at multiple points, which is inconvenient for welding and maintenance. The purpose of the utility model is to provide a sprocket welding platform with a multi-point positioning mechanism, which can fix various sprockets with different inner diameters, and can rotate the sprockets horizontally 360°, and the rotated sprockets can be Therefore, the sprocket can be positioned at multiple points, which is convenient for welding and maintenance, so as to solve the problems raised in the above-mentioned background technology. Compared with the prior art, the beneficial effects of the present utility model are: 1. Through the use of the chute, the slider, the clamping jaw, the conical column and the electric push rod, the inner ring of the sprocket can be sleeved on the three sets of clamping jaws; When the electric push rod is used to drive the conical column to move down, the claws are pressed to move along the chute, so that the claws can fix various sprockets with different inner diameters on the boss; 2. Through bearings, support columns, gears and positioning mechanisms When the sprocket on the boss is rotated, the conical column is raised by the electric push rod, the support plate is rotated, and the sprocket on the boss is driven to rotate, and the sprocket is rotated to the position that needs to be repaired. After that, mesh the limit pin with the tooth slot of the gear, and then lower the conical column through the electric push rod, so that the claws fix the sprocket, and the multi-point position of the sprocket can be positioned.