7.1) Individual valve functions could be made with a servo valve. An exact programmable, reproducible and memorisable setting is then available for this function.
Examples: release, pre-blow, support air
Among the machine settings there are machine settings of intensities or speeds that are important and those that are less important.
For example, the speed of penetration of the mould into the material is important for positive forming. The penetration should have a reproducible speed. When the same job step is repeated the reproducibility of the speed once optimised may be important for the quality of the part. The clamp frame speed is less important, it should be as fast as possible.
The intensity of the pre-blow blast can be very important, as well as that of the release. Here we have the possibility to select each valve as a servo valve. On principle, a servo valve is a ball valve with a setting that can be programmed and stored. The intensity once programmed is reproducible and is stored along with the part data. Once a setting has been optimised it is again safely available for repeat orders.
On principle each function that is actuated by a pneumatic valve can be fitted with a servo valve. Important and frequently selected options are:
- support air,
- lift table,
- lower table slowly,
- lower plug assist.
Altogether 100 steps are available for programming, which practically is an infinitely variable adjustment! Older techniques such as cascade valves are superseded by this technology.
The decision to use servo valves simply depends on the accuracy that is desired or required for repeated job steps. Furthermore there are widely differing assessments of the importance. Of course each additional and accurately reproducible function will upgrade the range of applications of the machine.
All servo valves can be retrofitted, though mostly not without a service on the spot.
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