Abstract: A method for operating actuators, such as pneumatic valves, in an injection molding machine especially for CD or DVD discs, or other molded articles. The timing of auxiliary processes (such as blowing air into the mold cavity or applying suction to the molded article in the cavity) is set as a function of the instant of completion of a process in the main sequence of operations (especially, cooling the molded article prior to ejection from the mold). In a set and display section the user sets a preferred time tn for each actuator to operate after, or before, a set completion time T of the main-sequence process (e.g., cooling). The time tn can be negative or positive, so that the various actuators turn on before or after the set completion time. A CPU calculates a starting time T±tn, and keeps the actuators on during a following interval tp. The starting time T±tn may be input to a memory, and output to the respective actuator.

Abstract: A method for testing injection-molded discs, such as CD or DVD discs, for the presence of residual stress by placing the discs between two polarizers uses a video screen provided as part of the injection machine's display unit as a light source. The screen is preferably made uniformly bright by removing text or drawings and being set to emit bright white light. The disc is set between and parallel to the two polarizing plates, whose axes are crossed. The machine operator views the screen through the crossed polarizers and freshly-made disc. Stress disturbs the polarization of light transmitted through the disc and shows molding defects as bright patches. The screen can be a CRT or a liquid crystal panel. The light is preferably made uniform by temporarily erasing letters or figures, used to show molding data, from the screen. Preferably a push-button activates and deactivates the bright white screen.

Abstract: Apparatus and method of monitoring an injection molding machine for molding a disc substrate, wherein a display device is controlled based on sensor outputs to display waveforms of operating parameters of the machine, including at least four parameters selected from among a speed and a pressure of injection of a material into a mold cavity, a mold clamping pressure, a backward movement amount of a movable mold half and a position of an injecting screw of the machine, such that each waveform represents a chronological change of a value of the corresponding parameter, and the display device is further controlled to indicate a point of time at which a sprue gate through which the material is injected into the mold cavity is closed, such that the point of time is indicated together with the displayed waveforms of the operating parameters displayed. Also disclosed is a computer-accessible recording medium storing a control program to be executed to practice the method.

Abstract: A device for detecting motion of a movable part of an injection-molding machine uses an encoder coupled to the part which outputs two square waves which are a quarter-cycle out of phase. The two waves are used to generate trigger pulses at four times either encoder waves' frequency. The direction of the phase shift, positive or negative, depends on the forward or backward direction of motion of the part, and the trigger pulses are generated in on one of two logic circuits depending on the direction of motion of the part. The quadrupling of the encoder wave frequency increases the accuracy of motion measurement. The device uses AND/OR logic to generate the two sets of trigger pulses. The trigger pulses are counted to determine the distance the part has moved. The trigger pulses are also latched, and higher-frequency clock pulses are counted during the latched period to calculate the part's speed.

Abstract: Mold clamping method and apparatus wherein a mold closing chamber of a mold clamping device is supplied with a pressurized fluid delivered from a hydraulic power source through a servo valve, to close a mold, and a mold clamping chamber independent of the mold closing chamber is also supplied with the pressurized fluid through the servo valve and a switch valve opened upon completion of the mold closing action, to thereby clamp the mold, and wherein a controller is provided to obtain a mold clamping force on the basis of a sum of a first force based on a fluid pressure in the mold closing chamber and a second force based on a fluid pressure in the clamping chamber, and feedback-control the servo valve such that the obtained mold clamping force coincides with a desired value.