This test accounts for 20% of the Final mark

Transcription

1 1º teste Controlo e Automação Industrial 3 Outubro de 15 Duração 1,5 hora This test accounts for % of the Final mark 1. (a) In today s world, manufacturing processes are becoming more automatized. As an Industrial Engineer briefly explain why is relevant (b) Automation can be achieved in several ways, as, for instance, flexible automation. Explain the advantage over rigid automation. (c) On an upper level, information can be passed directly to upper levels in the manufacturing information structure. Briefly explain what can be achieved with this. (a) The example studied in the class of rigid automation was pneumatics. Briefly explain which are the components of a pneumatic installation (b) Imagine that we need to perform an all-pneumatic cycle A + B C + C A B+ i. Write the equations using the graphical method ii. Did you got a Memory? Briefly explain when it is needed. Figura 1: Lab demonstration iii. Figure represents the basic pneumatic circuit. Can you explain the meaning of the symbols? 3. (a) In sequence b we want to repeat the inner movements 4 times A + B 4(C + C )A B+. Can yo draw a grafcet chart with this new cycle (b) Did you got a counter? Why did you put it working upside-down (c) What s the practical importance of the initial step (d) Can you imagine a real job where such cycle is used? 1

2 4. In the following diagrams are two grafcets with a difference on the transition out of the paralell. Explain what s the observable difference in the behavior of the systems SET CIL A RES CIL B RES CIL A RES CIL B 1 RES CIL A STH a 1 SET CIL A 3 SET CIL B 3 SET CIL B LD temp 1 LD temp 1 4 RES CIL B 4 RES CIL B STH b ORL temp STH b ANL temp 5 SET CIL A 5 RES CIL A STH a SET Set RES Reset STH Start High STL Start Low ANH And High ANL And Low temp is a defined timer, in a symbol table CIL N and n,n1 are the cylinders.

3 1. (a) In today s world, manufacturing processes are becoming more automatized. As an Industrial Engineer briefly explain why is relevant Production rate Price Quality / uniformity (b) Automation can be achieved in several ways, as, for instance, flexible automation. Explain the advantage over rigid automation. Smaller series Adaptivity Tayloring (c) On an upper level, information can be passed directly to upper levels in the manufacturing information structure. Briefly explain what can be achieved with this This allow to gather information on production, line balancing, in order to allow control, management, production control and outcome for instance.. (a) The example studied in the class of rigid automation was pneumatics. Briefly explain which are the components of a pneumatic installation Behind the circuit itself, it requires a compressed air distribution system. This is provided by a compressor located elsewhere. Air supply is controlled by a pressure valve, ans it contains little oil drops. Circuit itself is usually composed of cilinders together with 5/ valves, other valves as for instance the end od movement. (b) Imagine that we need to perform an all-pneumatic cycle A + B C + C A B+ i. Write the equations using the graphical method 3

4 A+ B- C+ C- A- B+ A B C Mem a1 a b1 b c1 c A+ A- B+ B- C+ C- M+ M- 4

5 One possible solution is A+ = b 1 St A = c M 1 B+ = a B = a 1 C+ = b m C = c 1 M+ = c 1 M = b 1 ii. Did you got a Memory? Briefly explain when it is needed. The memory is a 5/ valve, and is used to make a distinctive signal to identical states (sma sensor outputs) but followed by different orders. Figura : Lab demonstration iii. Figure represents the basic pneumatic circuit. Can you explain the meaning of the symbols? Cilinder with 5/ valve (distribution valve) End sensors The escapes are marked as a little triangle and air intake by the round symbol. 3. (a) In sequence b we want to repeat the inner movements 4 times A + B 4(C + C )A B+. Can yo draw a grafcet chart with this new cycle 5

6 RES CIL A;SET CIL B; RES CIL C LD cont 4 1 SET CIL A RES CIL B STH b 3 SET CIL C STH c1 4 RES CIL C ; DEC cont STH c ; ANL cont 5 RES CIL A STH a 6 SET CIL B (b) Did you got a counter? Why did you put it working upside-down It s easier, as the logical value corresponds to zero/non-zero (c) What s the practical importance of the initial step we must garantee that components are in first working position, in order to allow it goes. Otherwise dead locks can arise and /or damage. (d) Can you imagine a real job where such cycle is used? 6

7 We have two movements four strokes and the opposite initial movements. i. The first movements can be of fix something in place, e.g. a box, followed by the push of four items. ii. The first movements coud be a door opening (e.g. truck rear), followed by the push of 4 pieces of cargo inside. iii. Fix a container and provide some mixing of products inside 7

8 4. In the following diagrams are two grafcets with a difference on the transition out of the paralell. Explain what s the observable difference in the behavior of the systems SET CIL A RES CIL B RES CIL A RES CIL B 1 RES CIL A STH a 1 SET CIL A 3 SET CIL B 3 SET CIL B LD temp 1 LD temp 1 4 RES CIL B 4 RES CIL B STH b ORL temp STH b ANL temp 5 SET CIL A 5 RES CIL A STH a SET Set RES Reset STH Start High STL Start Low ANH And High ANL And Low temp is a defined timer, in a symbol table CIL N and n,n1 are the cilinders. Cilinder A moves in opposite directions left The return of A starts after B reach the final position or 1 seconds later, what comes first If B takes 5 seconds, A start after 5 seconds, if B takes 15 seconds A start after 1 seconds right The return of A starts after B reach the final position and 1 seconds have already gone, what comes last If B takes 5 seconds, A start after 1 seconds, if B takes 15 seconds A start after 15 seconds 8