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JICOSH Home > Case Studies > Case No.28
Case No.28

Worker crashed while adjusting punch press crankshaft

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[Circumstances of the Incident]

This accident occurred at a  plant that manufactures machines to develop photograph film, etc.

While the details  are not fully known, as the victim was engaged in processing work all by himself using a turret punch press, the accident apparently occurred as a result of the the process indicated below:

A turret punch press is a numerically controlled machine that can continue automatic processing once the operator has put the raw materials in place. The machine that the victim was using is estimated to have suddenly stopped during its operation because of some trouble.

After judging that some abnormality occurred to the crankshaft, the victim climbed onto the table and inserted a handcrank (a manual tool) to turn the crankshaft.

When the crankshaft suddenly started to move again, the handcrank was also rotated, striking a hard blow to the victim's head.

The handcrank was used roughly once a month as a manual tool  to adjust any gaps that occurred when the crankshaft stopped at the top dead center.  


The following can be considered as the causes of this accident.

1 When the turret punch press stops operations under the automatic mode, it must be changed to a manual mode to turn the crankshaft from the outside. Immediately after the accident, however, the machine's display indicated that it was in the automatic mode.

2. The grip portion of the handcrank the victim was using has a length of some 90cm, posing a risk of striking anyone within a wide reach. The victim was working within that range.

3. Although press machines are legally required to undergo specified voluntary inspection once every year, no inspection had been carried out on the relevant press.

[Type of business] Optical machines/lens manufacturing
[Type of accident] Crash
[Number of victims] One fatality