Abstract: A method of indicating an open/close state of a check valve of an injection molding machine simply and more accurately. The method detects screw rotational force during injection and displays in wave form on the screen of a display device changes in detected rotational force. An open/close state of the check valve can be indicated based on the waveform pattern displayed on the display screen because the screw rotational force waveform pattern changes when the check valve closes. From the fact that the screw rotational force waveform pattern changes when the check valve closes, the open/close state of the check valve can be indicated from the displayed waveform.

Abstract: Screw rotation speeds and screw rotating torques are measured at predetermined time intervals during metering and substituted into a previously-assumed function to determine a maximum screw rotating torque at each screw rotation speed. An allowable upper limit of screw rotating torque is set for each screw rotation speed on the basis of the determined maximum screw rotating torque. If a screw rotating torque exceeding the allowable upper limit is detected during metering after the allowable upper limit is set, the screw rotation is stopped or changed.

Abstract: When a resin passage of a check ring is opened, resin backflow occurs during time when an injection screw is moved forward, and a reverse rotational force is applied to the screw by resin backflow. On the other hand, when the resin passage is closed, there is no resin backflow and the reverse rotational force applied to the screw is greatly reduced. Consequently, after completion of metering process and before injection process, the screw is moved forward after the screw has been rotated in reverse a predetermined amount to prevent resin backflow. At this time, a maximum value of the reverse rotational force applied to the screw is detected. Until the detected maximum reverse rotational force reaches a reference value or less, the reverse rotation amount is increased sequentially and respective molding cycles are carried out.

Abstract: When a screw equipped with a check ring is moved forward, torque acting on the screw is detected, and whether the check ring is closed is determined on the basis of the detected torque. The screw is rotated in reverse when the check ring is determined not to be closed, and the reverse rotation of the screw is stopped when the check ring is determined to be closed. The reverse rotation of the screw is thereby controlled so that the screw is rotated in reverse by an optimal amount for reliably closing the check ring.

Abstract: While a check ring of a screw of an injection molding machine is in open state, an absolute value (|? resin pressure / ? rotation amount |) of a variation of a resin pressure per unit variation of the screw reverse rotation becomes greater than a predetermined reference value. However, after the check ring is closed, |? resin pressure / ? rotation amount | becomes equal to or less than the reference value. From this, detecting if the |? resin pressure / ? rotation amount | during reverse rotation of the screw, it is possible to determine that the check ring is closed or not. As a result, it is possible to obtain a screw reverse rotation amount which is optimal for reliably closing the check ring.

Abstract: An injection molding machine nozzle capable of letting heat escape from a nozzle end portion and preventing the occurrence of cobwebbing with a simple structure. A heat conducting member is mounted on the nozzle end portion. When the end of the nozzle is contacted against a mold the heat conducting member also contacts the mold. The heat conducting member is composed of the material having heat conductivity equal to or greater than that of the nozzle. The heat of the nozzle end portion is conducted to the heat conducting member and released at the mold, thus preferentially cooling only melted resin of the nozzle end portion. Cobwebbing does not occur even when the mold is opened and the molded article is removed because the melted resin of the muzzle end portion has been cooled.

Abstract: Torques and resin pressures applied to a screw are detected during the forward movement of the screw and coefficients of correlation between the detected torques and resin pressures are calculated. When the check ring is open, the flight of the screw receives resin pressure, and the screw torque increases proportionally to the resin pressure due to resin backflow, so the coefficients of correlation between the screw torques and the resin pressures are higher than a reference value. When the check ring closes, the flight of the screw no longer receive resin pressure, so the screw torque decreases and the coefficients of correlation become lower than the reference value. The check ring is determined to be closed when the coefficients of correlation become lower than the reference value.

Abstract: When the screw moves forward, resin backflow occurs. The backflow acts on the screw, applying torque to the screw. During forward movement of the screw, screw torque is produced as shown in FIG. 3A if the check ring is not worn, or as shown in FIG. 3B if the check ring is worn, because wear increases the backflow and delays the closure of the check ring. The magnitude of the peak screw torque and the associated time and screw position vary depending on the presence or absence of wear, so wear of the check ring is estimated from variations in these physical quantities.

Abstract: An injection molding machine estimates a check valve wear amount, making it possible to predict a check valve use limit. At start of injection, the check valve is at a position advanced a stroke S0 with respect to a screw position (a position of a check seat that contacts the check valve and closes a resin flow channel). As the screw advances, the check valve retreats and closes when the screw moves a distance X0. When the check valve is worn ?S (S1=S0+?S), it closes when the screw moves X1. Since the check valve stroke and the distance the screw moves until the check valve closes are proportional, S0/X0=S1/X1=a. Therefore, ?S=aX1?S0, and the wear amount ?S can be obtained by detecting the check valve closing position X1 and using this position X1 and the known stroke S0. The closing position is detected from the peak value of rotational force acting on the screw. Once the wear amount is obtained, the check valve use limit can be predicted from an allowable value of wear.

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: When a metering process is started, a screw rotates at a preset rotating speed, thereby carrying out back pressure control to keep the pressure of a resin at a preset pressure, and retreats. When the screw is located near a preset metering completion position, the control mode is switched to positioning control for the preset metering completion position, and a screw rotation stop command is outputted. The screw overruns for some distance before its rotation stops after it retreats and stops at the preset metering completion position. A resin quantity for the overrun is corrected to obtain a preset metered resin quantity by reversely rotating the screw by a rotational amount corresponding to the overrun.

Abstract: The invention provides an injection molding capable of adjusting a detection level with a simple structure and detecting a deposit level of the resin pellets near a plasticizing screw. A cooling jacket is mounted so that a resin supplying hole of the cooling jacket communicates with a resin supplying hole of a heating cylinder. A sensor head mounted on a sensor mounting plate is inserted into the resin supplying hole through a sensor insertion port provided on a hopper plate and a resin inlet and detects the deposit level of the resin pellets deposited in the resin supplying hole. Changing the extent of insertion of the sensor head enables the resin pellets deposit detection level to be changed, and further, enables the deposit level near the outer periphery of the screw to be detected. Setting the sensor detection direction perpendicular to the resin deposit direction enables dirtying of the sensor detection surface by the resin pellets to be reduced, thus enabling erroneous detection readings to be reduced.

Abstract: An injection molding machine capable of accurately detecting a rotational force exerted on a screw by resin backflow to easily evaluate states of resin backflow and closure of a check valve. In a state where the screw is stopped axially and rotationally after metering is finished, a load exerted on the screw in the rotational direction is detected. This load is a rotational force exerted on the screw from resin remaining between flights of the screw (resistance torque component). During injection, a load T exerted on the screw in the direction of rotation is detected, and the resistance torque component is subtracted from the detected load T to obtain a backflow torque component generated by resin flowing back through the check valve. By simultaneously displaying waveforms of backflow torque components in a plurality of molding cycles to be overlapped, stability of closure of the check valve is readily evaluated.

Abstract: A method of indicating an open/close state of a check valve of an injection molding machine simply and more accurately. The method detects screw rotational force during injection and displays in wave form on the screen of a display device changes in detected rotational force. An open/close state of the check valve can be indicated based on the waveform pattern displayed on the display screen because the screw rotational force waveform pattern changes when the check valve closes. From the fact that the screw rotational force waveform pattern changes when the check valve closes, the open/close state of the check valve can be indicated from the displayed waveform.

Abstract: An injection molding machine capable of appropriately adjusting a control condition for a reverse rotation of a screw and a method for adjusting the control condition. Molding is repeated with an amount of a reverse rotation of the screw performed after completion of metering and before injection to be varied in each molding cycle. In injection, resin flows backward until a check valve becomes closed. A peak value of a rotational force causing reverse rotation of the screw by the back flow of resin and other physical amounts are detected as indices of resin back-flow amount. An evaluation value of the control condition is obtained by inputting the indices of resin back-flow amount, metering time, etc. into an evaluation function. The value of screw reverse rotation amount with which the highest evaluation value is obtained is set for the screw reverse rotation.

Abstract: If a screw is moved forward after a metering step is completed, the screw moves in a state where a check ring on a tip end of the screw is in open state. Resin flows in a direction opposite to the injection direction. A rotational force is applied to the screw due to the backflow of the resin. If the check ring closes a resin passage, the rotational force acting on the screw is reduced. A peak time of the screw rotational force is detected as closing point in time of the check ring. Physical amounts such as a screw rotational force and a screw position at that timing are detected. Since the closing point in time of the check ring is precisely detected, correction of the injection/hold pressure switching position and the injection speed switching position can be adjusted more precisely. It is possible to precisely determine whether a molded article is non-defective or defective based on the detected physical amount.

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: When a metering process is started, a screw rotates at a preset rotating speed, thereby carrying out back pressure control to keep the pressure of a resin at a preset pressure, and retreats. When the screw is located near a preset metering completion position, the control mode is switched to positioning control for the preset metering completion position, and a screw rotation stop command is outputted. The screw overruns for some distance before its rotation stops after it retreats and stops at the preset metering completion position. A resin quantity for the overrun is corrected to obtain a preset metered resin quantity by reversely rotating the screw by a rotational amount corresponding to the overrun.

Abstract: The invention provides an injection molding capable of adjusting a detection level with a simple structure and detecting a deposit level of the resin pellets near a plasticizing screw. A cooling jacket is mounted so that a resin supplying hole of the cooling jacket communicates with a resin supplying hole of a heating cylinder. A sensor head mounted on a sensor mounting plate is inserted into the resin supplying hole through a sensor insertion port provided on a hopper plate and a resin inlet and detects the deposit level of the resin pellets deposited in the resin supplying hole. Changing the extent of insertion of the sensor head enables the resin pellets deposit detection level to be changed, and further, enables the deposit level near the outer periphery of the screw to be detected. Setting the sensor detection direction perpendicular to the resin deposit direction enables dirtying of the sensor detection surface by the resin pellets to be reduced, thus enabling erroneous detection readings to be reduced.

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.