GB1486883A - Manufacture control processes and apparatus therefor - Google Patents

Abstract

1486883 Injection moulding control SAABSCANIA AB 10 Feb 1976 [18 Feb 1975] 05230/76 Heading B5A [Also in Division G3] In a plastics injection moulding machine a sequentially operating system compares the actual temperature of the plastics (at 22) and the moulding pressure (at 23) at prescribed time intervals throughout the cycle with respective reference values and tolerances, produces an electrically readable statement as to whether or not any of the parameters are outside their tolerance, and issues an instruction for taking corrective measures which may be manual or autoteatic. The object is to ensure that the pressure/ time curve has a specific shape (Fig. 1, not shown). The complete sequence is as follows: (a) temperature, (b) mould filling time, i.e. time to reach set peak pressure, (c) to (e) the back pressure at times T2 to T4, measured from the end of (b). In each case the parameter error is obtained in comparators 19 ... 21 and is compared at 26 with the appropriate tolerance issued from 25. The result is resolved into a binary word, Fig. 3, each pair of terms represented whether a parameter is above, below, or within the tolerance band of its set value. This is converted into a corrective instruction, using a memory 31, to operate temperature, pressure, and ram motor regulators 14, 15, 12 and/or give an operator indication. None of the circuits are described.