Whitworth quick return mechanism : Definition, Working, Advantages

What is whitworth quick return mechanism ?

The Whitworth quick return mechanism is a mechanical device that converts rotational motion into reciprocating motion. It was invented by Sir Joseph Whitworth, a prominent British engineer, in the 19th century.

The mechanism consists of a rotating crankshaft connected to a connecting rod, which is in turn connected to a sliding block or slider. The slider moves along a straight guide or slider crank, creating a back-and-forth motion.

The distinguishing feature of the Whitworth quick return mechanism is that the forward stroke of the slider is faster than the return stroke. This speed difference allows for efficient operation in certain applications, such as shaping machines or slotting machines.

The mechanism works as follows: as the crankshaft rotates, the connecting rod translates the circular motion of the crankshaft into linear motion, causing the slider to move forward. However, during the return stroke, the connecting rod is configured in such a way that it creates a longer path for the slider to travel, resulting in a slower return speed.

The Whitworth quick return mechanism finds its application in various machines where a reciprocating motion is required, with a quick forward stroke and a slower return stroke. It has been widely used in shaping machines, slotting machines, and other industrial equipment.

Overall, the Whitworth quick return mechanism is a mechanical innovation that allows for efficient and controlled reciprocating motion, enabling the operation of various machines and tools in industries such as manufacturing and metalworking.

history

The Whitworth quick return mechanism was invented by Sir Joseph Whitworth, a prominent British engineer and inventor, in the 19th century. Joseph Whitworth was born in 1803 in Stockport, England, and he made significant contributions to the field of engineering during his lifetime.

Whitworth developed the quick return mechanism as a means to convert rotary motion into reciprocating motion with a speed difference between the forward and return strokes. The mechanism was specifically designed to improve the efficiency and productivity of machines used for shaping and cutting operations.

The invention of the Whitworth quick return mechanism is believed to have taken place in the mid-1840s. Whitworth’s innovative design incorporated a rotating crankshaft, a connecting rod, and a sliding block or slider that moved along a straight guide or slider crank. The mechanism enabled a faster forward stroke and a slower return stroke, resulting in more efficient machining processes.

The Whitworth quick return mechanism quickly gained recognition and was widely adopted in various industrial applications. It revolutionized the performance of shaping machines, slotting machines, and other machines that required reciprocating motion.

Joseph Whitworth’s contributions to engineering extended beyond the quick return mechanism. He was a proponent of standardization in engineering and played a crucial role in establishing the British Standard Whitworth (BSW) thread system, which became widely used in the manufacturing industry.

Whitworth’s dedication to precision engineering and his inventions left a lasting impact on the industrial landscape. His work influenced advancements in machinery, manufacturing processes, and engineering standards, and he is regarded as one of the leading figures of the Industrial Revolution.

The Whitworth quick return mechanism remains an important mechanical innovation, and its principles are still utilized in various machines and industrial applications today. It stands as a testament to Joseph Whitworth’s ingenuity and his contributions to the field of engineering.

parts of Whitworth quick return mechanism

Certainly! Here is an expanded description of the parts of the Whitworth quick return mechanism:

By working together, these four parts create an efficient and controlled reciprocating motion in the Whitworth quick return mechanism. The rotational motion of the crank is converted into an oscillating motion by the slider and slotted bar. The connecting rod then transmits this motion to the ram, enabling it to perform the desired action during the forward stroke.

components

Here is a simplified version:

how does Whitworth quick return mechanism works

The Whitworth quick return mechanism operates as follows:

This continuous rotation of the crank drives the reciprocating motion of the ram, allowing for efficient and controlled operation in various applications, such as shaping machines, slotting machines, and other industrial processes.

Whitworth quick return mechanism working:

The Whitworth quick return mechanism operates in two strokes: the forward stroke and the return stroke.

Forward Stroke:
During the forward stroke, the crank AB moves in a clockwise direction from point B2 to B1.
At the same time, the point X on the connecting rod moves in a clockwise direction from B1 to B2, and the ram moves forward from point Y1 to Y2.
The forward stroke is shown in the figure with a green dotted line.
In the forward stroke, the crank AB completes an angle α.

Return Stroke:
During the return stroke, the crank AB moves in a clockwise direction from point B1 to B2.
At the same time, the point X on the connecting rod moves in a clockwise direction from B2 to B1, and the ram moves in the opposite direction from point Y2 to Y1.
The return stroke is shown in the figure with a red dotted line.
In the return stroke, the crank AB completes an angle β.

This alternating motion of the crank, connecting rod, and ram allows for efficient back-and-forth movement. The forward stroke accomplishes a specific action, and the return stroke resets the mechanism for the next cycle.

Relation between time takes for forward & reversed stroke:

Here is the explanation in English:

1.During the crank’s clockwise movement from B2 to B1, the ram moves forward from Y1 to Y2. The time taken for the forward stroke of the ram is equal to the time taken for the crank to complete angle α.

2. When the crank moves clockwise from B1 to B2, the ram moves in the opposite direction from Y2 to Y1, completing the return stroke. The time taken for the return stroke of the ram is equal to the time taken for the crank to complete angle β.

From the given figure, we can observe that β is smaller than α. This means that the ram moves faster during the return stroke, while it takes more time for the forward stroke.

The ratio of the time taken for the forward stroke to the time taken for the return stroke can be expressed as:

Time for forward stroke / Time for return stroke = α / β

Alternatively, it can be written as:

Time for forward stroke / Time for return stroke = α / (360 – α)

This ratio indicates that the time taken for the forward stroke is longer compared to the return stroke, as α is greater than β. The specific values of α and β depend on the design and configuration of the mechanism.

application of Whitworth Quick Return Mechanism

The Whitworth quick return mechanism has found applications in various machines and industrial processes. Some of the notable applications include:

These are just a few examples of the applications of the Whitworth quick return mechanism. Its ability to provide a quick forward stroke and a slower return stroke makes it suitable for various machines that require reciprocating motion with differing speeds for specific operations.

advantages of Whitworth Quick Return Mechanism

The Whitworth quick return mechanism offers several advantages in its applications. Some of the key advantages are:

Overall, the advantages of the Whitworth quick return mechanism include increased efficiency, enhanced productivity, improved cutting performance, precision and control, versatility, and reliability. These advantages make it a popular choice for applications where efficient reciprocating motion is required.

disadvantages of Whitworth Quick Return Mechanism

While the Whitworth quick return mechanism offers several advantages, there are also some disadvantages associated with its use. Here are a few of the notable disadvantages:

It’s important to note that while the Whitworth quick return mechanism has these disadvantages, they may not be significant in every application. The suitability of the mechanism depends on the specific requirements and constraints of the intended use case. Engineers and designers need to carefully evaluate these factors when considering the implementation of the mechanism.

Reference : https://mm-nitk.vlabs.ac.in/exp/whitworth-mechanism/theory.html

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