Abstract: A monitoring device for an injection molding machine whereby the state of resin sheared by a rotating screw can be easily monitored. During the period from the start to end of metering process, the rate of heat generated by a heater for heating an injection cylinder is obtained by multiplying an on/off ratio B of the heater by a coefficient K and stored in a memory location THmem(n). Also, a time elapsed from the start of the metering is obtained by adding up a processing period T and stored in a memory location Tim(n). The heat generation rates of the heater stored in memory and corresponding to the respective elapsed times are displayed in graph form. The temperature of the injection cylinder represents heat generated by the heater plus heat generated due to resin shearing.

Abstract: A controller of injection molding machine capable of stabilizing a peak pressure of resin appearing when an injection process is switched to a pressure-holding process, by reducing the variation of the peak pressure. Resin pressure Pr is detected at every predetermined sampling period ?t. There is a time lag between the time at which the resin pressure reaches an injection/pressure-holding switch determining resin pressure P(v?p) and the sampling time t2 at which the resin pressure that has reached the value P(v?P) is detected. Hence, a difference Ve between the detected resin pressure value Pr? and the switch determining resin pressure P(v?p) is obtained. The transition time period T in which pressure should be changed from a pressure-holding start pressure Ps to a pressure-holding pressure Pp is corrected by T=T0??×Ve to make the transition time period T shorter when the difference Ve is greater, to thereby hold down the peak pressure Pmax. By this, the variation ?Pmax of the peak pressure Pmax is reduced.

Abstract: A controller for an injection molding machine capable of reducing an extension of a cycle time in a screw retreat process after the end of measurement, obtaining a more accurate and uniform measured resin amount, and determining measurement conditions in a short period of time. After the measurement is finished, the screw is stopped from rotating and retreated at a first speed V1. The screw is reversely rotated at a predetermined speed Rv in a set zone. As this is done, the screw is retreated at a second speed V2 lower than the first speed V1. After the reverse rotation zone is terminated, the screw is stopped from rotating and retreated at a third speed V3 to a set retreat stop position. By doing this, the cycle time can be made shorter than in the case where the retreat and reverse rotation of the screw are performed separately. Since the retreating speed of the screw is low while the screw is being reversely rotated, a sudden pressure change can be suppressed, so that precise measurement can be made.

Abstract: A crosshead position Cf for obtaining a set mold clamping force is obtained based on a mold touch position Ct obtained in mold clamping process in immediately preceding molding cycle, and a crosshead is allowed to move to the position Cf. During that time, it is determined whether a load La of a servomotor for mold clamping operation which drives a toggle mechanism exceeds a judgment load Ls, and a crosshead position Ca when the load La exceeds the judgment load Ls is stored as a mold touch position. In the next molding cycle, a crosshead position Cf where the set mold clamping force is obtained is obtained based on this stored mold touch position.

Abstract: There is provided the torque limiter for limiting a torque command to be output when pressure feedback control of the pressure holding step is performed. After the start of the pressure holding step, the torque limiter limits output toque of the servomotor for injection for a predetermined time period after the screw starts to move backward. As a result, the output torque in the backward direction of the screw is limited and reduced, whereby the speed of backward movement of the screw is reduced, and decrease of the pressure applied to the resin becomes moderate, thus abrupt drop of the pressure can be avoided.

Abstract: A method of and an apparatus for measuring and evaluating characteristics of material resin using an injection molding machine. Injections of resin are performed with different resin temperatures TCi and different injection velocities Vj to detect injection pressures Pr at set screw positions. Data of combinations (Pr, V, TC) of an N number of injection pressures, injection velocities and resin temperatures are obtained. An interdependency relation function PVT(t, v(x),x) expressing correlation among the injection pressure, the injection velocity and the resin temperature is obtained as PVT(t, v(x), x)=A(x)e??(x)Tv(x)?(x) according to a least square method using the obtained data, where ?(x) represents a degree of dependency on injection velocity influencing the injection pressure and “log A(x)??(x)T” represents a degree of dependency on resin temperature influencing the injection pressure.

Abstract: A screw is rotated at a set speed and retreated by performing back pressure control for keeping a resin pressure at a set pressure. When the retreat position of the screw reaches a change point set nearby a set metering completion position, the back pressure control for keeping the resin pressure at a set resin pressure is stopped. A command for positioning the screw at a metering completion position is output to position the screw at the metering completion position. At the same time, when a screw position reaches the change point, the screw is reversed by a set value at a set speed.

Abstract: A controller of an injection molding machine which compensates a delay in an injection velocity changeover and a delay at the time of changeover to the pressure-holding process, and is capable of more accurate and stable injection velocity control and changing control from the injection velocity control to pressure control. In the injection process, a motion command is outputted in every sampling period ? according to the command injection velocity. When a screw position overshoots the set velocity changeover positions Psw(2) and Psw(1), a motion command based on a velocity command of the next interval is outputted from the next period. However, there is time lag between the point when the set changeover position is reached and the point when the motion command is changed after detection thereof. There generates a motion deficiency in a motion amount shown by mark A and overshoot shown by B.

Abstract: An injection screw position Xa, injection speed Va, and injection pressure Pa are read. A deceleration distance D the injection screw moves from the point where the injection operation has been stopped at the current moment to be decelerated by maximum deceleration till the point where the injection speed is reduced to zero is determined from a corrected deceleration in which the amount of correction ? is added to a predetermined deceleration A inherent in the machine and the read injection speed Va. The determined deceleration distance D is multiplied by the amount of change in injection pressure with respect to the amount of change in the injection screw position to determine a predicted increment in pressure (D·?P/?X). The predicted increment in pressure is added to the current injection pressure Pa to determine an injection pressure Pa* predicted when the screw is suddenly decelerated at the current moment.

Abstract: The retraction of the screw is controlled on the basis of the pressure deviation between the set resin pressure and the detected resin pressure. Furthermore, the screw is caused to rotate at a set speed. Moreover, when the deviation between the metering completion position and the current screw retraction position drops to a value that is equal to or less than a set value, control of the retraction of the screw based on the pressure deviation is stopped, and the control is switched to positioning control based on the positional deviation. Furthermore, a screw rotational speed command in which the pressure deviation component between the set resin pressure and the current resin pressure is corrected from the screw rotational speed component that is decelerated in proportion to the positional deviation is determined and output.

Abstract: A controller and a method for an ejector mechanism in an injection molding machine for appropriately setting a terminal position of a forward motion of ejector pins of the ejector mechanism. The terminal position of the forward motion is set to a position where an elastic force of return springs does not exceed a retaining force of a brake device for retaining the ejector pins at the terminal position. The elastic force of the springs are detected during the ejector pins are moved forward. A position of the ejector pins immediately before the detected elastic force of the springs exceeds the retaining force of the brake device is determined and displayed on a display device as a criterial position. The terminal position of the forward motion of the ejector pins is set not to exceed the determined criterial position.

Abstract: A controller of injection molding machine capable of stabilizing a peak pressure of resin appearing when an injection process is switched to a pressure-holding process, by reducing the variation of the peak pressure. Resin pressure Pr is detected at every predetermined sampling period ?t. There is a time lag between the time at which the resin pressure reaches an injection/pressure-holding switch determining resin pressure P(v?p) and the sampling time t2 at which the resin pressure that has reached the value P(v?P) is detected. Hence, a difference Ve between the detected resin pressure value Pr? and the switch determining resin pressure P(v?p) is obtained. The transition time period T in which pressure should be changed from a pressure-holding start pressure Ps to a pressure-holding pressure Pp is corrected by T=T0??×Ve to make the transition time period T shorter when the difference Ve is greater, to thereby hold down the peak pressure Pmax. By this, the variation ?Pmax of the peak pressure Pmax is reduced.

Abstract: A crosshead position Cf for obtaining a set mold clamping force is obtained based on a mold touch position Ct obtained in mold clamping process in immediately preceding molding cycle, and a crosshead is allowed to move to the position Cf. During that time, it is determined whether a load La of a servomotor for mold clamping operation which drives a toggle mechanism exceeds a judgment load Ls, and a crosshead position Ca when the load La exceeds the judgment load Ls is stored as a mold touch position. In the next molding cycle, a crosshead position Cf where the set mold clamping force is obtained is obtained based on this stored mold touch position.

Abstract: A load determining device for an electrically-operated injection molding machine in which a load exerted on a movable part is detected based on the motor current or by an observer, with removing the influence of motor temperature. Upon start of continuous molding, a maximum load detected during retreat motion of an ejector or movable part is stored as a reference value Lr0. In every molding cycle, a maximum detected load Lra during the retraction of the ejector is determined. In the next molding cycle, load La detected during advance of the ejector is corrected based on the reference value Lr0 and the maximum detected load Lra to eliminate the influence of motor temperature rise, thereby determining the load Lfx(n) during the advance of the ejector. When there occurs a change in temperature of the ejector driving motor, the load detected based on the motor current or by the observer varies even if the actual ejector load is constant.

Abstract: An electric servo motor is controlled through a pressure control loop wherein a control object is the injection mechanism of an electric injection molding machine. A band elimination filter, which attenuates a frequency component of a band with predetermined width to be determined based on the resonance frequency of the control object, is provided in the pressure control loop.

Abstract: A monitoring device for an injection molding machine whereby the state of resin sheared by a rotating screw can be easily monitored. During the period from the start to end of metering process, the rate of heat generated by a heater for heating an injection cylinder is obtained by multiplying an on/off ratio B of the heater by a coefficient K and stored in a memory location THmem(n). Also, a time elapsed from the start of the metering is obtained by adding up a processing period T and stored in a memory location Tim(n). The heat generation rates of the heater stored in memory and corresponding to the respective elapsed times are displayed in graph form. The temperature of the injection cylinder represents heat generated by the heater plus heat generated due to resin shearing.

Abstract: The retraction of the screw is controlled on the basis of the pressure deviation between the set resin pressure and the detected resin pressure. Furthermore, the screw is caused to rotate at a set speed. Moreover, when the deviation between the metering completion position and the current screw retraction position drops to a value that is equal to or less than a set value, control of the retraction of the screw based on the pressure deviation is stopped, and the control is switched to positioning control based on the positional deviation. Furthermore, a screw rotational speed command in which the pressure deviation component between the set resin pressure and the current resin pressure is corrected from the screw rotational speed component that is decelerated in proportion to the positional deviation is determined and output.

Abstract: A screw is rotated at a set speed and retreated by performing back pressure control for keeping a resin pressure at a set pressure. When the retreat position of the screw reaches a change point set nearby a set metering completion position, the back pressure control for keeping the resin pressure at a set resin pressure is stopped. A command for positioning the screw at a metering completion position is output to position the screw at the metering completion position. At the same time, when a screw position reaches the change point, the screw is reversed by a set value at a set speed.

Abstract: An electric servo motor is controlled through a pressure control loop wherein a control object is the injection mechanism of an electric injection molding machine. A band elimination filter, which attenuates a frequency component of a band with predetermined width to be determined based on the resonance frequency of the control object, is provided in the pressure control loop.

Abstract: A method of and an apparatus for precisely determining a separating force of a molded product from a mold by an ejector in an injection molding machine. A load exerted on an ejector mechanism in operation without a product molded in the mold is constituted by an inner resistance of the ejector mechanism. The inner resistance includes frictional force produced within the ejector mechanism and resilient forces of springs for returning ejector pins to retracted positions thereof. On the other hand, the load exerted on the ejector mechanism in operation with a product molded in the mold is constituted by the inner resistance and the separating force of the molded product from the mold. Thus, a difference between the loads detected in driving the ejector mechanism with and without a molded product at each ejector position precisely represents the separating force of the molded product from the mold.