Abstract: A folding machine has workpiece sensing means including an emitter by which an "outside" corner in the workpiece edge approaching the operating locality of the machine can be sensed, such sensing causing the feed length by which the workpiece is advanced step-by-step through the operating locality to be reduced; this conventionally causes pleating in the folded over edge portion. In addition, delay means is provided by which, after the emitter has been re-covered by the workpiece, the feed length reduction continues for a given number of further feed steps.

Abstract: In a thermo-cementing and folding machine which has a suck-back facility, by which at the end of an adhesive-applying operation adhesive supplied through the nozzle (22) is sucked back into the nozzle so as to prevent `drooling`, auxiliary suck-back steps are introduced at timed intervals following the primary suck-back operation, through controlled amounts, in order to counter further risk of `drooling` caused by thermal expansion of the adhesive in the nozzle (22). The number of auxiliary suck-back steps is variable according to the adhesive supply rate at the time of termination of the adhesive-applying operation.

Abstract: A numerically controlled motor provides a drive at a rate which is proportional to rotation of an independently driven shaft. In addition, the ratio of such rate to such rotation can be varied by a control circuit by which, in response to each pulse supplied by an encoder on said shaft, an incremental value, corresponding to an analogue signal supplied by a potentiometer to an A-D converter, which converts said signal to said value, is supplied to an accumulator, which sums the successively supplied increment values and, at a predetermined cumulative value, "overflows", such "overflow" supplying a drive signal to the n.c. motor. The potentiometer is manually set by an operator to vary the increment value and thus the frequency of "overflow" in relation to shaft rotation. The control circuit also enables "reverse" and "fast forward" drive to the motor independently of the shaft.