To provide dozens of presses with a flexible heat source which will permit a range of temperature from 320 to 450 ° F. to suit various types of rubber with varying curing times. While an abundance of plant steam is available, it would be difficult to keep traps working on the dozens of presses for such a small load on each press. Flexible steamline connections to presses were difficult to keep tight and resultant steam leaks and moisture created unbearable working conditions.
Each transfer injection splicing press has two platens - an upper platen which is stationary and a lower platen on which the weatherstrip is placed, then raised to closed position by a hydraulic cylinder. A precise amount of uncured rubber stock is injected through the top platen into the cavities to make a secure splice without a lot of excess rubber flash around the joint.
Thermostatically controlled Chromalox Type PT Electric Strip .Heaters are installed in the top and bottom platens of each press, for a total of 2900 watts. A thermal switch is inserted in each platen to control the heaters. A magnetic contactor is also used so that the thermal switches control only the coil circuit and can give accurate temperature control with a variation of only a few degrees.
- It produces the exact molding temperatures for the various types of rubber used in the presses. Low to high temperatures are easily attained and maintained.
- Each of the dozens of presses is self-sufficient heat-wise - each is independent of any central heat source - any number of presses can be operated at one time without any complications.
- Maintenance is insignificant because of the long service life of Chromalox Strip Heaters - no expensive maintenance problems that would be experienced with any alternate heat source.
- It is clean - no combustion by-products, no leaky lines.
- Design of platens is simple and cost is reduced as no coring (drilling) is necessary as in the case of steam units.