Abstract: A drive arrangement comprises an a.c. induction motor (M1) having a rotary output shaft, and a drive control (FIG. 2), by which the speed of rotation of the shaft is controlled. The drive control comprises a signalling arrangement (e.g. a transducer (T) supplying an analogue signal converted by an analogue-to-digital converter (ADC) or a direct digital signalling arrangement) for supplying a digital signal having a value corresponding to the desired speed of rotation of the motor shaft, together with a processor (CPU) which receives the digital signal and at least one other input and processes the digital signal in accordance therewith. The processor supplies a corresponding, but modified, digital output signal to a digital-to-analogue converter (DAC) which converts the digital output signal to an analogue control signal and supplies it to an inverter which, in response thereto, drives the a.c. induction motor.

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.

Abstract: In a thermo-cementing and folding machine, a gear pump operates to supply adhesive at a rate which is dependent upon the speed of rotation of a main drive shaft, by which workpiece feeding means of the machine is driven. The machine has also a facility for varying the rate of feed of a workpiece by the workpiece feeding means without varying the speed of rotation of the main drive shaft. The ratio of the rotational speed of the shaft to the operating rate of the pump is varied in response to variation of the workpiece feed rate. This arrangement is achieved by computer control, the gear pump being driven by a stepping motor for this purpose. In addition, at the end of each work cycle, use of a stepping motor facilitates "suck back" of adhesive, and a "fast forward" adhesive upon initiation of the next work cycle.