Counterweight attachment technique

A drive shaft comprising:

• an aluminum tube having an outer surface facing radially away from an axis about which the drive shaft rotates,
• a steel counterweight having an inner surface and an outer surface, the inner surface of the counterweight being attached to the outer surface of the aluminum tube by resistance welding,
• a transition material disposed between the outer surface of the aluminum tube and the inner surface of the counterweight, the transition material having a first surface adjacent to the inner surface of the steel counterweight and a second surface adjacent to the outer surface of the aluminum tube, the first surface being steel and having an outward projection thereon and the second surface being aluminum without outward projections in an area to be welded;
• and
• a steel-steel bond formed between the inner surface of the counterweight and the first surface of the transition material, and an aluminum-aluminum bond formed between the second surface of the transition material and the outer surface of the aluminum tube by passing an electrical current through the counterweight, the transition material, and the aluminum tube while maintaining pressure on the outer surface of the counterweight against the aluminum tube.

A method of attaching a steel counterweight to a tubular aluminum drive shaft, the steel counterweight having an inner surface and an outer surface, and the aluminum drive shaft having an outer surface facing radially away from an axis about which the aluminum drive shaft rotates, the method comprising the steps of:

• forming an outward projection on the inner surface of the steel counterweight;
• disposing a transition material between the outer surface of the aluminum drive shaft and the inner surface of the steel counterweight, the transition material having a first surface adjacent to the inner surface of the steel counterweight and a second surface adjacent to the outer surface of the aluminum drive shaft, the first surface being steel and the second surface being aluminum, both the first and second surfaces without outward projections in an area to be welded;
• and
• resistance welding the counterweight to the aluminum drive shaft by passing an electrical current through the counterweight, the transition material, and the aluminum drive shaft while maintaining pressure on the outer surface of the counterweight against the drive shaft, thereby creating a steel-steel bond between the inner surface of the counterweight and the first surface of the transition material and an aluminum-aluminum bond between the second surface of the transition material and the outer surface of the aluminum drive shaft.

A drive shaft comprising:

• an aluminum tube having an outer surface facing radially away from an axis about which the drive shaft rotates,
• a steel counterweight having an inner surface and an outer surface, the inner surface of the counterweight having a projection thereon and being attached to the outer surface of the aluminum tube by resistance welding;
• a transition material disposed between the outer surface of the aluminum tube and the inner surface of the counterweight, the transition material having a first surface adjacent to the inner surface of the steel counterweight and a second surface adjacent to the outer surface of the aluminum tube, the first surface being steel and the second surface being aluminum, both the first and second surfaces without outward projections in an area to be welded;
• and
• a steel-steel bond formed between the inner surface of the counterweight and the first surface of the transition material, and an aluminum-aluminum bond formed between the second surface of the transition material and the outer surface of the aluminum tube by passing an electrical current through the counterweight, the transition material, and the aluminum tube while maintaining pressure on the outer surface of the counterweight against the aluminum tube.

A method of attaching a steel counterweight to a tubular aluminum drive shaft, the steel counterweight having an inner surface and an outer surface, and the aluminum drive shaft having an outer surface facing radially away from an axis about which the aluminum drive shaft rotates, the method comprising the steps of:

• disposing a transition material between the outer surface of the aluminum drive shaft and the inner surface of the steel counterweight, the transition material having a first surface adjacent to the inner surface of the steel counterweight and a second surface adjacent to the outer surface of the aluminum drive shaft, the first surface being steel and the second surface being aluminum, the transition material further having at least two layers including a steel layer the first surface and aluminum layer at the second surface;
• forming a steel projection between the inner surface of the counterweight and the first surface of the transition material for concentrating heat generation in the steel counterweight at a steel-steel bond formed between the inner surface of the counterweight and the first surface of the transition material and preventing excess heat from being transmitted to an aluminum-aluminum bond formed between the second surface of the transition material and the outer surface of the aluminum drive shaft when the counterweight is resistance welded to the aluminum drive shaft;
• and
• resistance welding the counterweight to the aluminum drive shaft passing an electrical current through the counterweight, the transition material, and the aluminum drive shaft while maintaining pressure on the outer surface of the counterweight against the drive shaft, thereby creating the steel-steel bond between the inner surface of the counterweight and the first surface of the transition material and the aluminum-aluminum bond between the second surface of the transition material and the outer surface of the aluminum drive shaft.

A drive shaft comprising:

• an aluminum tube having an outer surface facing radially away from an axis about which the drive shaft rotates;
• a steel counterweight having an inner surface and an outer surface, the inner surface of the counterweight being attached to the outer surface of the aluminum tube by resistance welding;
• a transition material disposed between the outer surface of the aluminum tube and the inner surface of the counterweight, the transition material having a first surface adjacent to the inner surface of the steel counterweight and a second surface adjacent to the outer surface of the aluminum tube, the first surface being steel and the second surface being aluminum, the transition material further having at least two layers including a steel layer at the first surface and an aluminum layer at the second face;
• and
• a steel projection between the inner surface of the counterweight and the first surface of the transition material for concentrating heat generation in the steel counterweight at a steel-steel bond formed between the inner surface of the counterweight and the first surface of the transition material and preventing excess heat from being transmitted to an aluminum-aluminum bond formed between the second surface of the transition material and the outer surface of the aluminum tube when the counterweight is resistance welded to the aluminum tube by passing an electrical current through the counterweight, the transition material, and the aluminum tube while maintaining pressure on the outer surface of the counterweight against the aluminum tube.

A metallic composite adapted for attachment to a tubular aluminum drive shaft by resistance welding for balancing the aluminum drive shaft during rotation, the aluminum drive shaft having an outer surface facing radially away from an axis about which the aluminum drive shaft rotates, comprising:

• a steel counterweight having an inner surface;
• a transition material having first surface and a second surface, the first surface being steel and the second surface being aluminum, the transition material further having at least two layers including a steel layer at the first surface and an aluminum layer at the second surface;
• and
• a steel projection between the inner surface of the counterweight and the first surface of the transition material for concentrating heat generation in the steel counterweight at a steel-steel bond formed between the inner surface of the counterweight and the first surface of the transition material and preventing excess heat from being transmitted to an aluminum-aluminum bond formed between the second surface of the transition material and the outer surface of the aluminum drive shaft when the counterweight is resistance welded to the aluminum drive shaft.