The Whitworth quick return mechanism is a type of mechanical linkage used to create a faster return stroke than the forward stroke in a reciprocating motion. It was invented by Sir Joseph Whitworth in the mid-19th century and is commonly found in machines like shapers and slotters.
How it Works:
The mechanism utilizes a crank and connecting rod arrangement, similar to a slider-crank mechanism, but with a crucial difference: the crank is connected to the connecting rod at a point that is offset from the center of the crank.
This offset creates a non-symmetrical motion. During the forward stroke, the crank rotates at a relatively constant speed, resulting in a slow and steady movement of the connecting rod and the driven member. However, during the return stroke, the offset creates a faster rotation of the crank, leading to a quicker movement of the connecting rod and the driven member.
Advantages:
- Increased Productivity: The quick return mechanism allows for faster cutting or shaping cycles, increasing production efficiency.
- Reduced Cycle Time: The faster return stroke significantly reduces the overall cycle time, boosting productivity.
- Versatility: The mechanism can be adapted to various machine designs and applications.
Applications:
- Shapers: These machines use the Whitworth quick return mechanism to move the cutting tool back and forth rapidly, allowing for efficient shaping of metal.
- Slotters: Slotters employ the mechanism to create slots or grooves in metal parts.
- Other Machine Tools: The mechanism can also be found in other machine tools where a quick return stroke is beneficial, such as planers and milling machines.
Example:
Imagine a shaper cutting a piece of metal. The forward stroke is used to perform the cutting action, which requires a slow and controlled movement. The return stroke, however, needs to be fast to minimize the time spent moving the tool back to its starting position. The Whitworth quick return mechanism achieves this by ensuring a faster return stroke than the forward stroke.
