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55 - 7947 Equipment Engineering and Design
Hydraulic Structural problem
A machine for making egg boxes out of paper pulp contains a large horizontally-moving platen carrying four heavy brass moulds, of total weight 800kg. The platen reciprocates with a period of 10 seconds, carried on two long Origa double-acting rodless pneumatic cylinders. At one end of its travel, the platen meets a vertically-travelling mould. (See sketch)
Two special fabricated steel brackets suspend the platen from the two sliding piston plates on top of the cylinders. The movement of the platen is cushioned by shock absorbers at each end of its travel.
After 14 days of continuous working, one of the brackets snapped and the platen fell to the floor.
1. What has caused the failure? Discuss how this has occurred and justify your answer. You may wish to use basic calculations if appropriate.
2. Design an improved fluid power (pneumatic/hydraulic) system to prevent the recurrence of the failure. Draw a suitable circuit to control and operate the new system.
3. Discuss other possible design improvements, drive systems, to the machine and the cost implications of the failure and the redesign.
All Calculations must be shown in full; otherwise no credit will be given.
All Theory and discussions must be directed and related to this problem. Lists of general/generic design issues, management techniques etc are not acceptable and will lose marks; all discussions must be related to the problem at hand.
References in Harvard format. Use diagrams or illustrations where useful.
Assessment criteria –PBL reports, module 7947 equipment engineering & design
Assessment criteria –PBL reports, module 7947 equipment engineering & design
See Marking Criteria sheet on Black Board.