Abstract: A product acceptance/rejection judgment method in an injection molding machine, which makes it possible to properly and quickly set judgment standard parameters and accurately judge whether a product is acceptable or not. Based on injection pressures and screw positions periodically sampled during each of a plurality of injection processes in nondefective product molding, an injection pressure curve group represented as a function of the screw position and an injection pressure curve group represented as a function of the time period elapsed from the start of injection are displayed on two coordinate systems (6, 7) on a display screen.

Abstract: An injection/hold pressure control apparatus which permits the production of high-quality molded articles without the need of using an expensive internal mold pressure sensor. When a plurality of points specifying a target injection/hold pressure curve represented as a function of the time period elapsed after the start of injection are manually input in succession, a processor (109) of a numerical control unit (100) calculates a group of target injection/hold pressure data on the basis of the target pressure curve drawn on a screen of a display unit (113), and stores them in a lookup table in a shared memory (102). Upon start of the injection, a comparator (11), connected to a pressure sensor (4) mounted on an injection screw (1) for detecting an actual injection/hold pressure, is connected to the numerical control unit through a first changeover switch (6).

Abstract: An injection apparatus of an injection-molding machine is described, including a servomotor for screw rotation including a pulse coder, the motor being driven in accordance with the difference between a command output from a control section of the injection-molding machine and an output from the pulse coder, thereby rotating a screw. During injection and pressure hold processes in which the motor is rendered nonoperative, the screw rotates as molten resin flows backward, if a check valve attached to the screw does not function normally, and this situation is detected as an abnormality of the check valve by a control section.

Abstract: A crank mold clamping apparatus capable of variably adjusting a mold-opening stroke for permitting usage of various types of molds which includes a numerical control apparatus for controlling a servomotor for driving a crank plate connected to a movable platen in forward and reverse rotation within a limited rotation region. The numerical control apparatus calculates a rotation angle between rotational positions of the crank plate corresponding to mold clamping and mold-opening end positions of the movable plate, respectively, so that the crank plate is rotated for the calculated rotation angle in the direction of mold-opening or mold-closing to perform mold-opening or mold-closing when a mold-opening stroke, determined in accordance with the size of a mold to be used, is supplied.

Abstract: A molding condition recording apparatus having a manual data input device with a CRT. The manual data input device has various keys for inputting parameters of various groups used for controlling injection, hold, metering and cylinder temperature, and for inputting molding defect indication data. A microprocessor for a programmable machine controller causes the input parameters and the molding defect indication data to be stored in a molding condition storage region of a shared memory (S5). The microprocessor then discriminates similarity between the thus stored molding condition and the molding condition already registered in a molding condition/molding defect storage file of a memory other than the shared memory (S7). If there is similarity between these molding conditions, the microprocessor causes the CRT to display an alarm message thereon together with the parameter already registered in the file and the mold defect indication data (S12).

Abstract: An automatic mold thickness adjusting method is provided, which is capable of effecting mold thickness adjustment in a short time by a low-cost mold clamping apparatus using a general-purpose motor for mold thickness adjustment, and of preventing an overcurrent from flowing in the motor. A crosshead is retreated to a position behind a position (LO) for production of a set mold clamping force when the crosshead reaches a lock-up position before a die-touch state is attained, or when the die-touch state is established in a crosshead position before the aforesaid position (LO), and a rear platen is advanced so that the die-touch state is attained.

Abstract: An injection control method for an electrically-operated injection molding machine is provided, which is capable of sharply increasing the injection speed of a low-priced electric injection molding machine. A command pulse train is supplied to a servo circuit for an injection servomotor whereby substantial rotary motion of the injection servomotor is initially prevented, as a result of the fact that the torque limit value (Ts) is set at a value sufficient to establish equilibrium between the output torque of the injection servomotor and the resin pressure acting on the injection screw. The error between the target rotational position of the injection servomotor and an actual rotational position thereof then is allowed to increase until it reaches a feed stop positional error (Fs).

Abstract: A method and an apparatus for pressure control of a motor-operated injection-molding machine, which are capable of effecting various modes of multi-stage pressure control smoothly without mounting a special servomotor on the injection-molding machine or replacing servomotor with another servomotor. When a shift is made from an injection process into a first pressure hole stage of a pressure hold process, or from each pressure hold stage to a pressure hold stage subsequent thereto, a central processing unit for numerical control calculates a modification amount. This modification amount is obtained by dividing a value, obtained by subtracting a maximum injection pressure or a torque limit value for a preceding pressure hold stage from a torque limit value for a subsequent pressure hold stage, by a required modification frequency. The modification frequency is obtained by dividing a predetermined switching time for the subsequent pressure hold stage by a hold pressure control operation execution period (S7).

Abstract: A method for positioning an operating unit of an electrically-operated injection molding machine at a predetermined operating position in an optimum manner, by using widths of positive-side and negative-side regions of an allowable positioning zone which are set independently of one another in accordance with the operating direction of the operating unit and the function to be achieved by the operating unit. Positioning of a screw at an injection-end position is completed when the actual screw position (PA) is equal to or less than the sum of a target injection-end position (PS) and the positive-side region width (W1), which is set to "0", and is equal to or larger than the value obtained by substracting the negative-side region width (W2) from the target position (PS), so that the screw is positioned at the target injection-end position or a screw-moving position which slightly exceeds the target position by a permissible distance, to thereby actually control an amount of shot.

Abstract: A method and an apparatus for controlling the back pressure of a motor-driven injection molding machine, capable of achieving an optimum plasticized state of a molten resin by continuously and smoothly varying a screw receding speed during metering.

Abstract: A drive system abnormality detecting apparatus of an injection-molding machine includes a microprocessor (19) for a controller, which causes a display unit (24) to indicate the occurrence of an abnormal situation. The drive of a servomotor (5) for an injection is stopped when the microprocessor concludes that the difference between the driving current of the servomotor and the output of a force detector, indicative of the resin pressure inside a cylinder (2), is not within predetermined permissible limits. The motor driving current and the detector output are individually periodically detected, during the time interval between the start of injection to the end of metering. By doing th is, the microprocessor prevents production of defective moldings, attributable to the occurrence of an abnormal situation in a screw drive system, and damage to components of the screw drive system and dies.

Abstract: A method for removing resin clogging a nozzle in a motor-driven injection molding machine, which is capable of removing resin clogged in the nozzle without an excessive load being continuously applied to a servomotor for driving a screw.When the nozzle is clogged with resin, pulse distribution to a servo-circuit is started to move the screw to a foremost position thereof (S1). If a feed stop state, wherein the pulse distribution is stopped by an increase of the deviation of an actual movement amount from a command movement amount for the servomotor above a predetermined value, is not ended before passage of a time set by a timer started at the time the feed stop state occurs (S3-S6), the forward movement of the screw is stopped by an alarm process (S7).

Abstract: A software servo control apparatus for use in an electrically-operated injection molding machine, which is capable of changing servo control variable constants, without the need of changing hardware arrangement, for greatly enhancing versatility for the machine, and of effecting appropriate pressure control. A servo control microprocessor (13) operates, in accordance with a servo control program, to determine a commanded current on the basis of a positional deviation amount, obtained from an output of a pulse encoder (5), and a moving command. The servo control microprocessor also determines an amount of a change in the output of the pulse encoder, and supplies a power amplifier (6) with the difference between the commanded current and an output of the same amplifier, for control of the drive of a servomotor (2). Further, the output of the amplifier is restricted to a value less than a commanded torque on the basis of an output of a pressure sensor (4) and the commanded torque.

Abstract: During a mold thickness adjustment process of an injection molding machine, a mold touch position at which the mold halves of a mold contact each other is detected, and the mold temperature is detected by means of thermocouples attached to the mold halves, respectively. Also, the mold thickness is obtained based on the position where a movable platen and a stationary platen of the injection molding machine contact each other, which is obtained previously, and the detected mold touch position.After a molding operation is started, the mold temperature (Tn1, Tn2) is detected in each of molding cycles, and the amount of change of the mold thickness (.DELTA.e) during the period between the preceding cycle and the current cycle is calculated (S14) based on the change of mold tempreature (.DELTA.T) during the period between the two cycles, the mold thickness (e), and the thermal expansion coefficient (k). The mold touch position for the current cycle (P) is obtained (S16) based on the calculated value.

Abstract: A method and an apparatus for automatic zero adjustment of an injection-molding machine, in which an axis driven by a servomotor can be automatically returned to its origin with accuracy and speed. When a one-revolution signal is produced after the axis reaches a deceleration position, a preset coordinate position of a reference point is written in a current-value register. Subsequently, when the axis driven toward an absolute position reaches the absolute position, the preset coordinate position of the reference point is corrected with use of a correction value calculated on the basis of a known coordinate position of the absolute position and the register value. When the axis driven toward the reference point reaches the corrected position, the preset reference point coordinate position is written in the current-value register.

Abstract: A switching control method which can smoothly effect transfer from a pressure holding step to a metering and kneading step in an injection-molding machine employing a servomotor as an injection shaft driving source for axially driving a screw. At completion of the pressure holding step, follow-up of an error register of a servo circuit driving the injection shaft servomotor is effected so as to bring an error amount accumulated within the error register to zero (steps S6 to S8). A value of torque limit acting on the servomotor is then switched from a set value for pressure holding to a set value for metering and kneading (step S11). Further, the follow-up of the error register is again executed over a predetermined period of time from the time of execution of the switching of the torque limit (step S13). Subsequently, transfer is effected to the metering and kneading step (step S14).

Abstract: A direct pressure type mold clamping apparatus for an injection-molding machine is capable of performing high speed mold closing and opening operations and of producing a required mold clamping force, without the use of a large sized motor, the mold clamping apparatus being driven by two motors. A movable platen is driven by servomotor at high speed to a die touch position. An error register of a servo circuit is supplied with distributed pulses which correspond to a moving amount from the die touch position to a set mold clamping force producing position. The movable platen is then driven in a mold clamping direction with a greater driving force by an induction motor. Thereafter, pulse signals outputted by a position detector are supplied to the error register corresponding to movement of the movable platen to gradually reduce an error value of the error register. When the error register value is reduced to zero, arrival at the set mold clamping force producing position is determined.

Abstract: A direct-pressure type mold clamping apparatus of an injection-molding machine, capable of performing high-speed mold closing and opening operations and of producing a required mold clamping force, without the use of a large-sized motor, is driven by two motors. The mold clamping apparatus includes a ball screw (6) engaging a ball nut (7) which is movable in unison with a movable platen (1). The ball screw is coupled to a servomotor (10) through a transmission mechanism (8, 9, 11, 17), and is also coupled to an induction motor (12) through the transmission mechanism, a speed reducer (14), and a clutch (15). A numerical control unit (20) controls the servomotor, the induction motor, and the clutch. After the movable platen, drive by the servomotor, is moved at high speed to a die touch position, the movable platen is driven to a set mold clamping force producing position with a greater driving force, by both the servomotor and the induction motor.

Abstract: An injection molding machine includes a numerical control system in communication with a host computer, the numerical control system having incorporated therein a computer, wherein the injection molding machine can itself start and stop in operation on the basis of stored data indicating that the injection molding machine is in a state capable of being operated or in a state incapable of being operated. Pre-processing is executed in response to a start-up signal from the host computer (steps S4 through S9). If a malfunction or abnormality happens during the pre-processing, the location and thus the existence of the abnormality is stored in memory of the numerical control system. After completion of the pre-processing, if the stored abnormalities are judged to be restorable on the basis of the storage contents in the memory, an abnormality restoration processing is executed (S17) and, subsequently, automatic operation is carried out (S11).

Abstract: A suckback method and apparatus is capable of positively effecting a suckback operation in an injection molding machine using a servomotor as an injection axis drive source for axially driving a screw. When the screw reaches a metering completion position, screw rotation is stopped and a follow-up operation for an error register is carried out so that an error amount accumulated in the error register becomes equal to zero (steps S1, S4, S5). Then, a torque limit for the servomotor and for application of back pressure is released (step S8), and the screw is driven backwardly by the servomotor by a predetermined suckback amount (step 11).