| 摘要 |
A wrought steel conduit bushing is provided. The bushing is formed from a blank by use of bending, stretching, setting, piercing, extruding, flattening, flaring and drawing techniques. Initially, a flat piece of iron is drawn into a cup and a flange is set. The closed end of the cup is reverse drawn to form a double shell or wall. The closed end of the cup is pierced and the resulting opening is extruded. The inner shell is then expanded to form a smooth annular ring with the outer shell to permit the passage of insulated wire without scarring the insulation. The inner shell is flared and flattened to complete the annular ring and to complete an inner cylindrical wall which may be threaded for mounting on rigid conduit. One or more ground lugs are then formed by bending a tang to provide an integral ground connection.
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