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MECHANISM / PIC MICROCONTOLLER

EXAMINATION QUESTION

V. Ryan © 2006-2017

 

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1. Part of a production process involves a hole being drilled in a piece of round section brass bar. The diagram below shows the bar ready to be held between two jaws leading to for drilling.

   

1a. In the space below design a mechanism that could be used to clamp both jaws together, holding the bar securely so that it can be safely drilled.

   
 

 

 

 

 

 

 

 

1b. Add labels and notes to explain your design.
 
 
 
 
   

POSSIBLE ANSWER

   

   

NOTES

   

The tommy bar is used to turn the screw thread. As this happens the thread pushes the movable jaw on to the brass bar. The bar is held securely in the ‘vee blocks’ and it can be drilled safely. When drilling is complete, the screw thread is loosened by turning the tommy bar in the opposite direction - releasing the bar.

   
 
 
1c. Name the most suitable material for the manufacture of the jaws.
 
   
2d. Why is the material you have named the most suitable?
 
 
   
POSSIBLE ANSWERS
   
1c. Name the most suitable material for the manufacture of the jaws.
Hardened Steel
   
1d. Why is the material you have named the most suitable?

The steel jaws are tougher than the brass bar and will not wear down over time. This means that the jaws will not need replacing.

 
 

2. In order the increase the speed of the production line an automatic clamping device has been included. When the bar is to be drilled it is clamped automatically in the right position. A PIC Microcontroller monitors inputs to control the automatic system.
A dark sensor (sensor A) detects when the brass bar is the correct position and a micro-switch (Sensor B) detects when the guard is in position. When both switches are activated the clamping mechanism works.

   
   

2a. In the space below draw the systems diagram that represents INPUT - PROCESS - OUTPUT for the operation of the production line shown above.

   
   
POSSIBLE ANSWER
   
   
 
   
 
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