Countermeasures against slug
What is slug?
During stamping, if the material is punched, the punched piece is originally removed, but the piece sticks together with the punch and floats up, sometimes getting under the material.
This phenomenon is called "Slug".
If the stripper is pushed in this state, the material may be dented by slug, resulting in product defects or damage to the die.
Early detection of slug can work below.
・Reducing the number of defective products produced
・Prevention of outflow of defective products
・Reduction of die damage
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We have the device PS-482/484/488, PS-474, PS464/462 for detecting slug to take measures against slug by measuring the displacement of the stripper for each stroke.
*Our slug detector = Stripper displacement detector
Detection procedure of our slug detector
In general, slug detector uses an eddy-current proximity sensor installed in the die to monitor the closest distance at about B.D.C between the stripper and the sensor for each stroke. It detects changes of the closest distance due to slug and then notifies an abnormality to the press machine.
Our bottom dead center detector (slug detector) captures the closest distance (sample value) between the stripper and the eddy-current proximity sensor for each stroke.
It averages the acquired sample values to create a standard value.
If the difference between the standard value and the sample value (displacement) exceeds the setting value, it will be judged as slug.
Setting valuesu can be set both + and - against the standard value.
The standard value changes with each stroke. therefore, it is less susceptibility of noises such as the material thickness fluctuation and the B.D.C fluctuation due to SPM fluctuation etc. when detecting slugs, and can detect slight displacement caused by slugs.
*Our eddy-current proximity sensor
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The standard value (average of the sample value of the time before last and the last time) is updated continually.
- The material thickness fluctuation
- The B.D.C fluctuation due to the temperature expansion of the press and the die, etc.
- The drift of the internal voltage due to the temperature fluctuation of the detector, etc.