Abstract: A two-stage flow-control electrohydraulic servovalve has a pilot-stage (14) and a second-stage valve spool (6) mounted for sliding movement relative to a body (1). The pilot-stage (14) is arranged to provide an output pressure, which is used to selectively displace the second-stage spool (6) relative to the body, to establish flow through the second-stage. The second-stage spool has a plurality of lobes, which are overlapped with respect to passageways communicating with the control ports (3,4). A spool position feedback servoloop is closed about the second-stage valve spool and the pilot-stage. The improvement provides a compensation circuit (21) for modifying the command signal (e.sub.c) so as to compensate for the "dead zone" in the normal second-stage flow-to-displacement characteristics, such that the second-stage output flow will be substantially proportional to the command signal.

Abstract: A control circuit (10) for an extrusion die (13) is operatively arranged to supply a command signal (e.sub.c) to an actuator (24,25) for controlling the movement of a mandrel (11) relative to a die head (12) as plasticized material is extruded through an orifice (14) to form a parison (15). The controller includes a memory (28) for receiving and storing a plurality of initial set points supplied from a keypad (29). A recalculation circuit (42) is operatively arranged to recalculate the magnitude of each set point according to the equation S.sub.n(r) =(S.sub.n(i) -G.sub.1)B+G.sub.2, where S.sub.n(r) is the recalculated value a particular set point, G.sub.1 is a first reference die gap, G.sub.2 is a second reference die gap, B is a scaling factor, and S.sub.n(i) is the corresponding initial set point stored in memory. The recalculation circuit is operatively arranged to supply each recalculated set point to the memory to replace the initial set point stored therein.

Abstract: An apparatus for controlling the tool position in a machine tool, permitting position data and adjustment speed data to be altered without the operator having to consider the actual value of such data. The apparatus comprises an alteration memory adapted to have alteration data in the form of absolute values or percentages entered thereinto and to hold such data available for a subsequent calculation process involving the data relating to the tool position or adjustment speed, respectively.The calculation is automatically carried out with the aid of gating means within the apparatus. Alternatively possible is an overwriting of data with values entered without calculation.

Abstract: A control circuit is adapted to control the movement of a pintle relative to the die head of extrusion apparatus. A command signal is supplied to a signal generator, which produces a first output signal in the form of a series of continuous voltage triangles, and a second output signal in the form of unit pulses. An impedance matrix contains a plurality of potentiometers which may be remotely connected to a summing amplifier. The potentiometers are arranged in a numerical order. Odd-numbered potentiometers are supplied with the triangular output signal from the signal generator. Even-numbered potentiometers are supplied with the signal generator triangular output signal, but which has been phase-shifted by half the width of one triangle. The pulse output from the signal generator is supplied to a decoder, which successively connects pairs of numerically-adjacent potentiometers with the summing amplifier during overlapping time intervals.

Abstract: Apparatus is provided for generating a self-adjusting saw-tooth wave in response to an input signal containing a plurality of successive start pulses separating time intervals of variable length. The apparatus includes an integrator for generating a ramp signal during each time interval, a comparator for comparing the value of the integrator output signal with a predetermined maximum value and for supplying, at the end of each time interval, the difference therebetween as a correction signal to modify the slope of the ramp signal generated during the next subsequent time interval. The slope of the ramp signal is adjusted to accommodate variations in length of successive time intervals so that the peak value of such ramp signals will equal a predetermined maximum value at the end of successive time intervals of equal length.

Abstract: A jig is provided for storing setting data of apparatus having a plurality of adjacent slidable setting members. The positions of the members relative to the frame and to each other determines the setting data of the apparatus. The jig includes a plurality of bars mounted on a frame for independent sliding movement relative thereto, and a set screw for releasably holding the bars in desired positions. Each bar has an end face arranged to be selectively contacted by an aligned setting member.

Abstract: An improved regulator is provided for varying the rotational speed of a screw conveyor arranged to supply material to a variable-volume chamber having a piston slidably mounted in a cylinder. The regulator produces a sum signal proportional to the algebraic sum of positive input signals reflecting the desired degree of chamber filling and the desired discharge volume, and negative input signals reflecting the actual filling volume and the actual degree of chamber filling. This sum signal is converted to a proportional time-dependent signal which is used to adjust the speed of the conveyor. The conveyor speed is increased or decreased by an amount depending on the magnitude and polarity of the sum signal. In use, the regulator practices an improved method of regulating the speed of a conveyor.

Abstract: A control circuit is adapted to control the movement of a pintle relative to the die head of extrusion apparatus. A command signal is supplied to a signal generator, which produces a first output signal in the form of a series of continuous voltage triangles, and a second output signal in the form of unit pulses. An impedance matrix contains a plurality of potentiometers which may be remotely connected to a summing amplifier. The potentiometers are arranged in a numerical order. Odd-numbered potentiometers are supplied with the triangular output signal from the signal generator. Even-numbered potentiometers are supplied with the signal generator triangular output signal, but which has been phase-shifted by half the width of one triangle. The pulse output from the signal generator is supplied to a decoder, which successively connects pairs of numerically-adjacent potentiometers with the summing amplifier during overlapping time intervals.