WO2017126193A1

WO2017126193A1 - Method for ending molding cycle of injection molding machine

Info

Publication number: WO2017126193A1
Application number: PCT/JP2016/082774
Authority: WO
Inventors: 祐一朗有馬; 岡崎　芳紀; 努坂尾
Original assignee: 宇部興産機械株式会社
Priority date: 2016-01-21
Filing date: 2016-11-04
Publication date: 2017-07-27
Also published as: CN108290330B; JP6107984B1; CN108290330A; JP2017128059A

Abstract

A method for ending a molding cycle of an injection molding machine includes: a first average running torque calculation step of calculating a first average running torque of a screw 16 in a measurement step; a second average running torque calculation step of calculating a second average running torque in a plurality of times of molding cycles from respective first average running torques of the plurality of times of selected molding cycles and setting the calculated second average running torque as a stable molding torque reference value; and an average running torque comparison step of comparing the first average running torque with the stable molding torque reference value. In the average running torque comparison step, a molding cycle in which the first average running torque reaches an established molding end value from the stable molding torque reference value or falls below the established molding end value is regarded as a final molding cycle to end the molding cycle.

Description

Method for ending molding cycle of injection molding machine

The present invention includes an injection device having an injection device that rotates a screw in a heating barrel and plasticizes a resin material supplied into the heating barrel from the rear of the screw while flowing toward the front of the screw. The present invention relates to a method for finishing a molding cycle of a molding machine.

First, a measurement process for plasticizing (in a molten state) molten resin for one molding cycle in an injection apparatus of an injection molding machine will be described. As shown in FIG. 1, the inline screw type injection device 1 is disposed in a heating barrel 15 in which a material supply unit 14 such as a hopper is formed on the rear side (right side in FIG. 1), and rotatably in the heating barrel 15. A screw 16, a metering drive mechanism (not shown) such as a servo motor for rotating the screw 16, and a heating means 15 a disposed on the outer peripheral surface of the heating barrel 15 are provided. The screw 16 has a spiral flight 16a on its outer peripheral surface. Further, when the screw 16 is disposed in the heating barrel 15, the resin flow path 10 that is spirally continuous is heated by the space between the flights 16 a, the outer peripheral surface of the screw 16, and the inner peripheral surface of the heating barrel 15. It is configured to be formed in the barrel 15. In such an in-line screw type injection device 1, by rotating the screw 16 by the measuring drive mechanism, the pellet-shaped (granular) resin material 14a supplied from the material supply unit 14 into the heating barrel 15 is made of resin. It flows toward the front of the screw 16 (left side in FIG. 1) through the flow path 10. Further, in the in-line screw injection device 1, while the resin material 14a is flowing, the thermal energy from the heating means 15a, the contact between the rotating flight 16 and the resin material 14a, or the contact between the resin materials 14a. The resin material 14a is heated and plasticized (melted state) by the generated shear energy. FIG. 1 shows the start of the weighing process of the in-line screw type injection device 1, and the screw 16 is at the measurement start position (injection completion position).

The resin material 14a flows toward the front of the screw 16, and plasticization (melting) proceeds as the heat receiving distance and the heat receiving time in the resin flow path 10 increase. The resin material 14a is almost completely plasticized when it passes through the check ring 18 in front of the screw 16, and reaches the space (reservoir 15b) in front of the screw head 17 at the tip of the screw 16. In the measuring step, the nozzle 13 at the tip of the heating barrel 15 is pressed by a sprue bush of a mold (not shown), and the resin cutoff opening switching valve (not shown) arranged on the nozzle 13 or the mold is shut off. . Thereby, since the storage part 15b forms the closed space, the plasticized resin material 14a (molten resin) can be stored in the storage part 15b.

Here, the check ring 18 is a backflow prevention valve, and is a hollow cylindrical (ring-shaped) valve body disposed coaxially with the screw 16 so as to be movable by a predetermined amount in the longitudinal direction of the screw 16. The check ring 18 itself is not provided with a drive source for moving the check ring 18 in the longitudinal direction with respect to the screw 16. The check ring 18 is pressed to the front of the screw 16 and moved to the forward limit by the flow pressure of the resin material 14a for flowing the resin flow channel 10 to the front of the screw 16 during the measuring step. Is configured to be maintained in an open state.

On the other hand, in the in-line screw type injection apparatus 1, not only the screw 16 is rotated, but also for injection filling, it can be moved back and forth at a predetermined speed and pressure in the longitudinal direction by an injection driving mechanism (not shown). . The screw 16 is rotated at a predetermined speed by the metering drive mechanism at the same time while the pressure (back pressure) in the forward direction (left side in FIG. 1) is applied by the injection drive mechanism. As a result, the resin material 14a plasticized in the resin flow path 10 is continuously stored in the storage portion 15b in a state where substantially the same pressure as the back pressure in the forward direction is maintained. As a result, as shown in FIG. 2, the screw 16 moves backward while being rotated. Even during the backward movement of the screw 16, the pressure of the resin material 14a in the reservoir 15b in front of the check ring 18 and the pressure of the resin material 14a in the rear resin flow path 10 are substantially the same pressure (≈back pressure). For this reason, the check ring 18 remains in its forward limit position, and the resin channel 10 is kept open. FIG. 2 shows the time when the weighing process of the in-line screw type injection device 1 is completed, and the screw 16 is at the measurement completion position (injection start position).

In the injection drive mechanism, measuring means for measuring the longitudinal position of the screw 16 in the heating barrel 15 is arranged. In such an injection drive mechanism, the plasticized resin material 14a required for one molding cycle is determined from the distance from the measurement start position (injection completion position) to the retracted position of the screw 16 (measurement completion position / injection start position). In other words, the amount of resin material 14a necessary for one injection filling (amount of metered resin) is generally calculated. In the injection drive mechanism, it is determined that the measurement process is completed by moving the screw 16 back to a preset position (measurement completion position / injection start position), and the rotation of the screw 16 and the resin material 14a to the material supply unit 14 are determined. Stop supplying. In the injection drive mechanism, the resin shut-off switching valve in front of the screw 16 is opened, and the screw 16 is advanced at a predetermined speed (injection speed) by the injection drive mechanism, whereby the resin material 14a of the storage portion 15b is made to move. The mold cavity in the mold can be injection filled.

At the start of injection filling, the pressure of the resin material 14a in the reservoir 15b in front of the check ring 18 and the pressure of the resin material 14a in the rear resin flow path 10 are substantially the same pressure (≈back pressure). Therefore, the check ring 18 cannot follow the forward movement of the screw 16. On the other hand, due to the forward movement of the screw 16, a sealing surface (not shown) for closing the resin flow path 10 formed at the retreat limit position of the check ring 18 in the screw 16 moves forward and is formed on the rear end surface of the check ring 18. The resin flow path 10 is closed because it abuts against the sealing surface (not shown). In addition, after the resin flow path 10 is closed, the pressure of the resin material 14a in the reservoir 15b suddenly increases with the advance operation of the screw 16, and the check ring 18 is moved rearward of the screw 16 during the advance operation of the screw 16. Press. Therefore, during the forward movement of the screw 16, the backflow of the resin material 14a in the storage portion 15b to the resin flow path 10 is prevented, and the resin material 14b can be injected and filled into the mold cavity.

After the injection filling process is completed, the molding cycle is completed after holding pressure and cooling solidification time. In a mold clamping device (not shown), a product removal step is performed in which the mold is opened and the resin molded product is taken out of the mold. Further, in the in-line screw injection apparatus 1, as shown in FIG. 1, the screw 16 is rotated and the supply of the resin material 14a from the material supply unit 14 is started, and the measurement process for the next molding cycle is started. Is done.

In the injection filling process of the immediately preceding molding cycle, the material supply unit from the injection start position (measurement completion position) of the screw 16 shown in FIG. 2 to the injection completion position (measurement start position) of the screw 16 shown in FIG. The screw 16 is advanced in a state where the supply of the resin material 14a from 14 is stopped. Therefore, when the supply of the resin material 14a is started, the resin flow path 10 within a predetermined distance from directly below the material supply unit 14 is in a sparse state (starvation state) with almost no resin material 14a. Here, “within a predetermined distance from directly below the material supply unit 14” means that the retraction distance of the screw 16 during the measurement process (retraction amount S shown in FIG. 3) (the screw 16 during the injection filling process) from directly below the material supply unit 14 Of the screw 16 in the longitudinal direction.

Next, the case of terminating the molding cycle in the injection molding machine including the inline screw type injection device 1 will be described with reference to FIGS. In order to simplify the drawings, the inside of the heating barrel 15 is simply illustrated in these drawings.

FIG. 3 shows a state in the heating barrel 15 at the start of the measurement process (at the start of rotation of the screw 16) when the resin material 14a is supplied to the material supply unit 14 in the measurement process described above. A reservoir 15b in front of the screw 16 (check ring 18) in the heating barrel 15 is filled with the resin material 14a plasticized in the previous molding cycle. Also, the resin flow path 10 behind the check ring 18 is filled with the resin material 14a except for “within a predetermined distance from directly below the material supply unit 14” although the plasticized state is different.

When the molding cycle is ended from the state shown in FIG. 3, first, a material supply stop command is transmitted to a material supply device (not shown) to stop the supply of the resin material 14a to the inline screw injection device 1. Even if the supply of the resin material 14a from the material supply unit 14 is stopped, a large amount of the resin material 14a is held in the heating barrel 15 although the plasticization state is different. Therefore, the molding cycle is continued even after the supply of the resin material 14a is stopped. Therefore, after the supply of the resin material 14a is stopped, as the molding cycle proceeds, the resin material 14a of the heating barrel 15 gradually decreases as shown in FIG.

Here, in the measurement process, when the resin material 14a necessary for one injection filling is not stored in the storage portion 15b, that is, the screw 16 does not retract to a preset position (measurement completion position / injection start position) ( If the time required for the screw 16 to reach the measurement completion position) or the time until the screw fluctuates fluctuates, a criterion for determining whether the measurement completion position of the screw 16 has not been reached is required.

For this reason, in addition to reaching the measurement completion position (injection start position) of the screw 16 in addition to the determination that the measurement completion position of the screw 16 has not been reached, the measurement process is started (start of rotation of the screw 16 or start of retraction of the screw 16). In general, the weighing time is monitored and compared with the set weighing time. If the measurement completion position of the screw 16 is not reached during the continuous molding cycle, the metering time is monitored without stopping the molding cycle and stopping the molding cycle. Made. Further, after the molding cycle is stopped, the resin material remaining in the injection apparatus (plasticizing mechanism) is plasticized and discharged (purged) to the outside.

There are various methods for purging (operation). In the inline screw injection apparatus 1, after the molding cycle is finished, first, the inline screw injection apparatus 1 is separated from the mold, and the inline screw injection apparatus. A resin receiving container or the like is arranged in front of the nozzle 13 at the tip of 1. Thereafter, the screw 16 at the injection completion position (measurement start position) is rotated at that position at a constant speed to plasticize the resin material 14a remaining in the in-line screw type injection apparatus 1, while the resin receiving container or the like A method of discharging (purging) is generally used.

As described above, in the molding of a resin molded product, the molding cycle is stopped when the measurement completion position of the screw 16 is not reached during the weighing process. Therefore, even when the supply of the resin material 14a is stopped in order to end the molding cycle, the resin material 14a in the heating barrel 15 gradually decreases in the subsequent molding cycle as shown in FIG. When the situation where the measurement completion position of 16 is not reached is reached, the molding cycle is stopped, so that a defective product with insufficient metering resin amount should not be molded.

However, when the supply of the resin material 14a is stopped in order to finish the molding cycle, several molding cycles before the situation where the measurement completion position of the screw 16 is not reached (the screw 16 is metered) are reached. Also in the molding cycle reaching the completion position), a defective product with insufficient metering resin amount is molded.

This is mainly due to two reasons due to the decrease in the resin material 14a in the injection device (heating barrel 15). That is, in the weighing process after the supply of the resin material 14a is stopped, as shown in FIGS. 3 and 4, the resin material 14a in the heating barrel 15 at the start of the weighing process gradually decreases for each molding cycle. To go. The screw 16 in the measuring process is controlled at a constant speed at a predetermined rotational speed by a measuring drive mechanism. For this reason, as the resin material 14a in the heating barrel 15 decreases, the rotational torque of the metering drive mechanism for maintaining the predetermined rotational speed of the screw 16 decreases, and accordingly, the storage unit 15b has a unit time. A situation occurs in which the volume of the resin material 14a that is allowed to flow is reduced. This situation does not occur in a normal measurement process in which the supply of the resin material 14a is continued (reason 1).

On the other hand, the backward movement of the screw 16 during the measuring process is controlled so that the back pressure applied in the forward direction by the injection drive mechanism is constant. For this reason, with the decrease in the resin material 14a in the heating barrel 15, the retraction speed of the metering drive mechanism for maintaining the back pressure applied to the screw 16 decreases, and accordingly, the storage unit 15b has a unit time. A situation occurs in which the volume of the resin material 14a that is flowed per contact also decreases. This also does not occur in the normal weighing process (reason 2).

For the

reasons

1 and 2 described above, when the supply of the resin material 14a is stopped in order to end the molding cycle, even in the molding cycle in which the screw 16 reaches the measurement completion position, the reservoir 15b A situation occurs in which the volume of the stored resin material 14a is smaller than the volume stored in a normal weighing process, and thereby a defective product having an insufficient amount of measured resin is formed. Therefore, even when the supply of resin material is stopped, defective products with insufficient metered resin amount are not molded, and the molding cycle is terminated at the timing to minimize the amount of resin material held in the injection device. Therefore, there is a demand for a method for completing a molding cycle of an injection molding machine.

Here, in order to detect the lack of the resin material in the injection device (plasticizing mechanism) at the time of detection of material shortage or material shortage during molding, or purge processing (operation), the injection molding of Patent Document 1 is performed. A material detection method for a machine and a method for stopping a purge operation of Patent Document 2 are known.

The material detection method of the injection molding machine of Patent Document 1 is intended to detect the presence or absence of a material (resin material) in a heating cylinder (heating barrel) during a molding cycle or during a purge operation. The material detection method of the injection molding machine of patent document 1 detects the magnitude | size of the load current of a drive motor at the time of the action | operation of a screw rotational drive motor, and an electric current detection value becomes below the preset current setting value, and an electric current setting value A material non-detection signal is output when the following time continues for a preset time or more.

The method of stopping the purge operation in Patent Document 2 is intended to accurately detect the time when the resin discharged from the plasticizing apparatus (injection apparatus) runs out when the purge operation is automatically performed. According to the method for stopping the purge operation in Patent Document 2, after the purge operation is started, the screw driving torque is monitored while rotating the screw at a predetermined rotational speed in the plasticizing apparatus, and the driving torque is set to a predetermined value. The screw rotation is stopped immediately or after a predetermined time has elapsed.

JP-A-4-334426 JP 2006-088557 A

In order to detect the loss of the resin material in the injection device, the material detection method of the injection molding machine of Patent Document 1 detects the load current of the screw rotation drive motor, and the method of stopping the purge operation of Patent Document 2 Monitors the screw drive torque. In other words, both the material detection method of the injection molding machine of Patent Document 1 and the purge operation stop method of Patent Document 2 monitor the rotational torque of the screw, and when this rotational torque becomes a set value or less, It is determined that the resin material in the injection device has reached a desired holding amount (remaining amount).

Here, it is common to control the rotation speed to be constant in the screw during the measuring process or purging operation. In that case, the rotational torque required to keep the rotational speed of the screw constant is not constant but varies. For example, as shown in FIG. 3, even when the weighing process is performed under a normal weighing state from a state where the inside of the heating barrel 15 (plasticizing mechanism) is almost filled with the resin material 14a, the rotational torque of the screw is fluctuate. Further, as the storage volume of the plasticized resin material 14a in the storage portion 15b increases, the rotational torque generated in the screw 16 changes with fluctuation. Furthermore, unexpected unexpected factors (for example, the resin in front of the screw 16 from directly below the material supply unit 14 due to a change in the material supply state such as the supply of the resin material 14a from the material supply unit 14 being stopped). If a flow failure or the like generated in the resin material 14a held in the flow path 10 occurs, fluctuations or changes in the rotational torque generated in the screw 16 may increase, but not decrease.

Also, in the purge operation, when the purge operation proceeds under a normal purge operation state, the rotational torque generated in the screw decreases as the resin material in the injection device decreases. However, since the speed control for rotating the screw at a predetermined rotational speed is also performed in the purge operation, the rotational torque necessary to keep the screw rotational speed constant is not constant, and the rotational torque generated in the screw Decreases with fluctuations. Furthermore, the change in the plasticized state of the resin material in the injection device is maintained by maintaining the heating control of the heating means of the injection device against unexpected unexpected factors and a decrease in the resin material in the injection device. In view of the above, fluctuations in the rotational torque generated in the screw cannot be avoided (see FIG. 2 of Patent Document 2 / screw driving torque (rotational torque) from the start to the end of the purge operation).

Therefore, as in the material detection method of the injection molding machine of Patent Document 1, the load current in a state where the resin material in the injection device has reached the desired holding amount with respect to the fluctuating load current of the screw rotation drive motor. Even if the current setting value is set as a pinpoint, the state in which the load current has decreased to the current setting value is a state in which the load current has temporarily decreased to the current setting value due to fluctuation, and the desired holding amount It may not be in a state of reaching.

Furthermore, in the material detection method of the injection molding machine of Patent Document 1, the condition that the time below the current set value continues for a preset time or longer is added to the detection condition. This is because the load current of the screw rotation drive motor temporarily changes due to fluctuations in the rotation torque due to a decrease in the screw rotation torque as described above, unexpected unexpected factors, etc. It is presumed to avoid false detection due to the drop to the value. However, since the time during which the state reduced to the current set value is maintained varies depending on the type, situation, and degree of the factors of these fluctuations, it is difficult to set a suitable set time. As a result, in the material detection method of the injection molding machine of Patent Document 1, even if the load current decreases to the current set value and the time equal to or less than the current set value continues for a preset time or more, There still remains a possibility that the resin material in the injection apparatus is not in the state of reaching the desired holding amount.

Thus, in the material detection method of the injection molding machine of patent document 1, when supply of the resin material is stopped, the resin material in the injection device has reached the desired holding amount, that is, the resin amount is insufficient. The screw torque corresponding to the timing at which the defective product is not molded and the amount of the resin material held in the plasticizing mechanism is minimized is obtained pinpoint by test molding or the like, and this is also set as a desired value. There is a high possibility that the above state cannot be detected accurately.

On the other hand, in Patent Document 2, when the rotational torque of the screw is reduced to a set value, the resin material in the injection device has reached a desired holding amount (in the case of Patent Document 2, the resin material in the injection device is In addition to the method of “no longer being used”, the moving average value of the rotational torque of the screw is monitored, and when this moving average value drops to the set value, the resin material in the injection device has reached the desired holding amount A method (alternative method) is described (claim 2 of patent document 2 and others).

Here, the moving average value is “in the time series data, an average value for each certain interval is obtained while shifting the interval, and if a graph is created using the moving average value, a long-term A smooth curve representing the trend is obtained ”(extracted from the Internet site“ Statistical WEB / Statistical Tips / Moving Average Calculation Method ”). In the alternative method described in Patent Document 2, a setting value is provided for the moving average value of the screw rotation torque, not the screw rotation torque, so that the purge operation as shown in FIG. From the start to the end, it is considered that the screw driving torque (rotational torque) accompanied by the fluctuation can be converted to a smooth fluctuation to some extent as shown in FIG. Accordingly, the alternative method described in Patent Document 2 erroneously detects a decrease to a temporary set value due to a variation caused by a decrease in rotational torque generated in the screw during the purge operation as described above. It seems to contribute to avoiding the problem.

However, the moving average value as described above is disclosed in Japanese Patent Application Laid-Open No. 2003-259542. The change and fluctuation of the rotational torque of the screw during the purge operation without rotation in the longitudinal direction of the screw are terminated from the start of the purge operation. Can be adopted by treating up to one time series. On the other hand, in the weighing process, since one weighing process in one molding cycle is one time series, when it is determined that the resin material in the injection device has reached a desired holding amount, Patent Document 2 The moving average value can be used only for changes or fluctuations in the rotational torque of the screw during one metering process of a certain molding cycle.

Therefore, it is conceivable to set an appropriate set value on the basis of the average rotational torque obtained by moving and averaging one weighing process of one molding cycle as one time series. However, an unexpected sudden factor or the like may occur in the one weighing process, and in this case, an abnormal rotational torque is generated as compared with a case where the factor does not occur. The average rotational torque obtained by moving average of one weighing process including such abnormal rotational torque is a predetermined amount compared with the average rotational torque obtained by moving average of one weighing process in which the factor does not occur. There is a possibility that a difference has occurred, and therefore there is a problem that the reliability of the reference average rotational torque is low.

In this way, the moving average value described in the purge operation stopping method of Patent Document 2 can be adopted for changes or fluctuations in the rotational torque of the screw during one weighing process that is one time series. Even if an appropriate set value is set based on the average rotational torque obtained by moving average with respect to changes and fluctuations in the rotational torque of the screw during one metering process of a certain molding cycle, There is a problem that the reliability of the rotational torque is low. Therefore, in the method of stopping the purge operation of Patent Document 2, when the supply of the resin material is stopped, the resin material in the injection device has reached a desired holding amount (that is, a defective product with insufficient resin amount is molded). This is a reference for obtaining a screw rotation torque (corresponding to the timing of minimizing the amount of the resin material held in the plasticizing mechanism) by test molding and comparing it with the set value. Since the reliability of the average rotational torque is low, there is a possibility that the desired state cannot be accurately detected.

The present invention has been made in view of the above-described problems. Specifically, after the supply of the resin material is stopped, a defective product with insufficient resin amount is not molded, and the resin material in the injection apparatus It is an object of the present invention to provide a molding cycle end method for an injection molding machine that can end a molding cycle at a timing at which the amount of holding is minimized.

An object of the present invention is to provide an injection apparatus that rotates a screw in a heating barrel and plasticizes the resin material supplied into the heating barrel from the rear of the screw toward the front of the screw. A molding cycle end method of an injection molding machine having
A first average rotational torque calculating step of calculating a first average rotational torque of the screw in a metering step of storing the plasticized resin material up to a set amount in the storage unit of the injection device in one molding cycle;
From the arbitrary molding cycle, the first average rotational torque calculation step is performed in each of a plurality of selected molding cycles, and the plurality of selected molding cycles are determined from each of the obtained first average rotational torques. And calculating a second average rotational torque at the same time, and setting the second average rotational torque as a stable molding torque reference value;
An average rotational torque comparison step of comparing the first average rotational torque in any one molding cycle after setting the stable molding torque reference value with the stable molding torque reference value;
Have
In the average torque comparison step, the first molding torque reaches a set molding end value from the stable molding torque reference value, or a molding cycle in which the first molding torque falls below the set molding end value is defined as a final molding cycle. This is achieved by an injection molding machine molding cycle termination method that terminates the molding cycle in the cycle.

In the molding cycle end method of the injection molding machine according to the present invention, it is preferable not to perform the first average rotational torque calculation step in a predetermined number of molding cycles after the start of molding.

Moreover, in the molding cycle end method of the injection molding machine according to the present invention, from any molding cycle, the first average rotational torque calculation step is performed for each molding cycle,
From the arbitrary molding cycle, start the second average rotational torque calculation step for each molding cycle,
In the average rotational torque comparison step, the first average rotational torque in the molding cycle immediately after the molding cycle in which the stable molding torque reference value is set in the second average rotational torque calculation step is set in the immediately preceding molding cycle. You may make it compare with the said stable shaping | molding torque reference value made.

Furthermore, in the molding cycle end method of the injection molding machine according to the present invention, the selected multiple molding cycles in the second average rotational torque calculating step is set as one set, and the stable molding torque is set for each set. In addition to setting a reference value, in the average rotational torque comparison step, the first average rotational torque of each molding cycle of the one set is compared with the stable molding torque reference value set in the immediately preceding one set. Also good.

On the other hand, in the molding cycle end method of the injection molding machine according to the present invention as described above, each time the molding cycle is restarted after a stop operation including a temporary stop of the molding cycle, the second average rotational torque In the calculation step, it is preferable to set the stable molding torque reference value.

In the molding cycle end method of the injection molding machine according to the present invention, the screw in the heating barrel is rotated, and the resin material supplied into the heating barrel from the rear of the screw is caused to flow to the front of the screw. A method for ending a molding cycle of an injection molding machine having an injection device to be plasticized in between,
A first average rotational torque calculating step of calculating a first average rotational torque of the screw in a metering step of storing the plasticized resin material up to a set amount in the storage unit of the injection device in one molding cycle;
From the arbitrary molding cycle, the first average rotational torque calculation step is performed in each of a plurality of selected molding cycles, and the plurality of selected molding cycles are determined from each of the obtained first average rotational torques. And calculating a second average rotational torque at the same time, and setting the second average rotational torque as a stable molding torque reference value;
An average rotational torque comparison step of comparing the first average rotational torque in any one molding cycle after setting the stable molding torque reference value with the stable molding torque reference value;
Have
In the average torque comparison step, the first molding torque reaches a set molding end value from the stable molding torque reference value, or a molding cycle in which the first molding torque falls below the set molding end value is defined as a final molding cycle. In order to finish the molding cycle in the cycle, after the supply of the resin material is stopped, the defective product with insufficient resin amount is not molded, and the molding cycle ends at the timing to minimize the amount of resin material retained in the injection device Can be made.

It is a schematic sectional drawing which shows the time of the measurement process start of the inline screw type injection device of the injection molding machine based on Example 1 of this invention. It is a schematic sectional drawing which shows the time of completion | finish of the measurement process of the in-line screw type injection apparatus of the injection molding machine based on Example 1 of this invention. It is a schematic sectional drawing which shows the inside of the heating barrel at the time of the measurement process start in which the resin material is supplied to the material supply part. It is a schematic sectional drawing which shows the inside of the heating barrel at the time of the measurement process start after supply of the resin material to a material supply part was stopped. In Example 1, it is an image figure for demonstrating the process for complete | finishing a shaping | molding cycle. In Example 1, it is a graph which shows the 1st average rotational torque etc. of the screw in the measurement process of the shaping | molding cycle just before ending a shaping | molding cycle. In Example 2, it is an image figure for demonstrating the process for ending a shaping | molding cycle.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

With reference to FIG.5 and FIG.6, the molding cycle completion | finish method of the injection molding machine based on Example 1 of this invention is demonstrated. The method for ending the molding cycle of the injection molding machine according to the first embodiment will be described on the assumption that it is implemented by the injection molding machine having the inline screw type injection device 1 described above with reference to FIGS.

FIG. 5 is an image diagram for explaining a process for ending the molding cycle in Example 1 with the horizontal axis as the number of molding cycles (N). The molding cycle (A1 to A5) from the start of the molding cycle (N = 1) to the fifth (N = 5) is defined as the A molding cycle. Unlike FIG. 3 showing the start of the weighing process when the resin material 14a is being supplied to the material supply unit 14, in the molding cycle A1 immediately after starting a new molding cycle, the resin flow path 10 of the screw 16 is not filled. The screw 16 is rotated in a state where there is no resin material 14a, and supply of the resin material 14a is started. Therefore, it takes a predetermined time for the plasticization to proceed while the supplied resin material 14a flows to the front of the screw 16 through the resin flow path 10, and to start storing (measuring) in the storage portion 15b. .

In addition, the temperature of the inline screw type injection device 1 (such as the heating barrel 15 and the screw 16) in the cold state is increased to a temperature suitable for molding a non-defective product after the supply of the resin material 14a is started and stabilized (saturating). It takes a predetermined time to do so. Stable (saturating) until the temperature of the in-line screw injection device 1 is raised to a temperature suitable for molding a non-defective product, or the heat receiving and heat dissipation of the in-line screw injection device 1 itself is balanced. In the meantime, part of the thermal energy due to the shearing energy generated when the heating means 15a, the contact between the rotating flight 16a and the resin material 14a or the contact between the resin materials 14a is not plasticization of the resin material 14a, These resin materials 14a are consumed to raise the temperature of the in-line screw type injection device 1 in direct contact.

On the other hand, before the molding cycle is started, that is, before the resin material 14a is supplied, it is possible to start heating by the heating means 15a of the heating barrel 15 and raise the temperature of the in-line screw injection apparatus 1 in advance. . However, in the molding cycle, the heat history of the inline screw injection device 1 until saturating with heat reception and heat dissipation cannot be complementarily controlled only by the heating control of the heating means 15a as described above. Therefore, the plastic material of the resin material 14a is not plasticized and injection filling is performed, and only the heating control of the heating means 15a is performed. It is difficult to suitably raise the temperature and saturate so that can be molded.

Further, on the mold clamping mechanism and the mold side (not shown), for the same reason, a predetermined time is required until the temperature is raised to a predetermined temperature and stabilized (saturated), and the injection filling of the resin material 14a is performed. In addition, it is difficult to appropriately raise the temperature and saturate the mold clamping mechanism and the mold only by controlling the temperature of a mold temperature adjusting device (temperature controller) connected to the mold side. Therefore, in the A molding cycle after the next molding cycle A2, even if the weighing process can be started from the state shown in FIG. 3, the plasticized state of the resin material 14a in the storage portion 15b and the mold side In order to reach a molding cycle in which the temperature adjustment is stable and a good product can be molded, a predetermined number of molding cycles are required. Naturally, in the molding cycle until reaching the molding cycle capable of molding this good product, a defective product is molded. Between the average rotational torque generated in the screw 16 (first average rotational torque) in the molding cycle in which defective products are molded, and the first average rotational torque in the molding cycle in which non-defective products can be molded, there is an unavoidable variation. Difference more than the difference caused by.

Here, in Example 1, the average value of the rotational torque generated in the screw 16 (first average rotational torque) in the weighing step of storing the plasticized resin material 14a in the storage portion 15b up to a set amount in one molding cycle. ) Is calculated (first average rotational torque calculating step). While the supply of the resin material 14a into the heating barrel 15 is continued, the first average rotational torque calculated in the first average rotational torque calculation step is the second average rotational torque in the second average rotational torque calculation step described later. It is an important numerical value used to calculate the rotational torque.

Also, as described above, the rotational torque generated in the screw 16 fluctuates even when measurement proceeds under normal measurement conditions. In the material detection method of the injection molding machine disclosed in Patent Document 1, the load current in a state in which the resin material in the injection device has reached a desired holding amount during the measurement process in which the rotational torque generated in the screw 16 fluctuates is pinpointed. Since the setting value is set, the above-described problem occurs. On the other hand, in Example 1, the influence of the fluctuation | variation which arose in the rotational torque of the screw 16 can be reduced by averaging the rotational torque which arises in the screw 16 in a measurement process, and handling it as a 1st average rotational torque. Therefore, the rotational torque of the screw 16 can be a stable reference.

Therefore, in order to exclude the unstable molding cycle before reaching the molding cycle capable of molding a good product as described above, the first average rotational torque calculation step is performed in a predetermined number of molding cycles after the molding is started. Preferably not. Depending on the resin molded product, its size and required quality, as well as the molding conditions and injection conditions, the number of molding cycles to reach a molding cycle capable of molding a good product from the start of molding varies. Therefore, it is preferable to obtain in advance a suitable predetermined number of times not to perform the first average rotational torque calculation step by test molding or the like. In Example 1, it is assumed that the predetermined number of times is five, and a good product can be molded from the sixth molding cycle B1.

Next, the first average rotational torque calculation process described above is performed in each of a plurality of selected molding cycles from the sixth molding cycle B1 in which a good product can be molded, and the first average rotational torque of each molding cycle is calculated. . In order to facilitate understanding of the description, in Example 1, the selection method and the number of molding cycles are set to five consecutive times (from the sixth molding cycle B1 to the tenth molding cycle B5). These five molding cycles are collectively referred to as a B molding cycle. In the first embodiment, the first average rotational torque calculation step is performed in each molding cycle (B1 to B5) of the B molding cycle, and the first average rotational torque of each molding cycle is calculated. The first average rotational torque calculated in each of the molding cycles B1 to B5 is summed up almost simultaneously with the completion of the measuring step of the tenth molding cycle B5 (the last molding cycle in the B molding cycle), and the total value is obtained. Is calculated by dividing the number of times by the number of times selected (5 in the first embodiment). Then, the second average rotational torque calculated in the B molding cycle is set as a stable molding torque reference value by a control device (not shown). Thus, the second average rotational torque calculation step is a step of calculating the second average rotational torque and setting the calculated second average rotational torque as the stable molding torque reference value.

In the following description, the stable molding torque reference value set in the second average rotational torque calculation step of the B molding cycle is TB. On the other hand, the first average rotational torque in the eleventh molding cycle immediately after the tenth molding cycle for which the stable molding torque reference value TB is set is the stable molding torque reference value TB that is set in the immediately preceding tenth molding cycle. (Average rotational torque comparison process).

Further, in parallel with the second average rotational torque calculation step in the B molding cycle, a new second average rotational torque calculation step is started from the seventh molding cycle. In the following description, five molding cycles that are continuous from the seventh molding cycle (from the seventh molding cycle C1 to the eleventh molding cycle C5) are collectively referred to as a C molding cycle. Then, substantially simultaneously with the completion of the measurement process of the eleventh molding cycle C5 (the last molding cycle in the C molding cycle), the second average rotational torque is calculated and set as the stable molding torque reference value TC. Similarly to the B molding cycle, the first average rotational torque in the twelfth molding cycle immediately after the eleventh molding cycle for which the stable molding torque reference value TC is set is set in the immediately preceding eleventh molding cycle. It is compared with the stable molding torque reference value TC (average rotational torque comparison step).

Further, in the D molding cycle starting from the eighth molding cycle and the E molding cycle starting from the ninth molding cycle, the second average rotational torque calculation step is newly performed in the same manner, so that the stable molding torque reference value is obtained. TD and TE are set respectively. Then, an average rotational torque comparison step of comparing the first average rotational torque in the molding cycle immediately after the molding cycle in which the respective stable molding torque reference values are set with the stable molding torque reference value set in the immediately preceding molding cycle. Let it be done.

As described above, in Example 1, the first average rotational torque calculating step and the second average rotational torque calculating step are started from the sixth molding cycle in which good products can be molded, and the stable molding torque reference value is set. In the subsequent molding cycle, an average rotational torque comparison step for comparing the stable molding torque reference value calculated and set from the most recent set number of molding cycles with the first average rotational torque in the molding cycle immediately thereafter is performed for each molding cycle. It is characterized by letting it be done.

Here, FIG. 6 shows the first average rotational torque (solid line 1) of the screw 16 in the measuring step of a molding cycle in which a non-defective product can be molded in a certain test molding, and three types of candidate values (dotted line 2, It is a graph which shows the continuous line 3 and the dashed-dotted line 4). As described above, the first average rotational torque is used to calculate the second average rotational torque for one set of molding cycles (five continuous molding cycles) to which the molding cycle related to the first average rotational torque belongs, It is used for comparison with a stable molding torque reference value obtained by one set of molding cycles immediately before the molding cycle related to the first average rotational torque. The set molding end value is a reference value for determining the final molding cycle in the present invention, and is a difference of the first average rotational torque with respect to the stable molding torque reference value (second average rotational torque). In the first embodiment, a method of obtaining a set molding end value by test molding or the like based on a stable molding torque reference value (second average rotational torque) having high reliability as a reference value will be described.

In the graph of FIG. 6, the horizontal axis indicates the number of molding cycles (N), and the 50th molding cycle and thereafter are shown. The vertical axis indicates the rotational torque of the screw 16, and is not the rotational torque value itself, but the percentage when the rated rotational torque of the servomotor of the metering drive mechanism (not shown) that rotates the screw 16 is 100%. It is displayed. The square plotted on the number of times of each molding cycle is the first average rotational torque of the metering step in the molding cycle, and a straight line connecting these squares (solid line 1) is the first average rotational torque of the screw 16. Shows changes. Although slight fluctuations that may be caused by factors that cannot be avoided are confirmed, the difference in the first average rotational torque for each molding cycle is not large and relatively stable from the 50th to the 58th molding cycle. Shows the value.

Here, the dotted line 2, the solid line 3 and the one-dot chain line 4 in FIG. 6 are the stable molding torque reference values set in each molding cycle (the second average rotational torque of the screw 16 of the molding cycle of the five most recent molding cycles). The three types of candidate values of the set molding end value based on the are plotted and smoothly connected. Explaining each candidate value, the dotted line 2 is the stable molding torque reference value reduced by 10% (90% of the stable molding torque reference value), and the solid line 3 is the stable molding torque reference value reduced by 20%. The one-dot chain line 4 is obtained by reducing the stable molding torque reference value by 30% (70% of the stable molding torque reference value).

In the test molding of Example 1, the supply of the resin material 14a is stopped after the completion of the weighing process of the 58th molding cycle in FIG. Therefore, in the 59th and subsequent molding cycles, the first average rotational torque of the screw 16 decreases for each molding cycle. Since the second average rotational torque (stable molding torque reference value) calculated from the first average rotational torque in each of the latest five molding cycles is also affected by the decrease in the first average rotational torque, the dotted line 2, the solid line 3 and The alternate long and short dash line 4 also decreases with each molding cycle. In the case of the molding cycle of FIG. 6, in the average rotational torque comparison step of the 60th (triangle display) molding cycle, the first average rotational torque is a value obtained by reducing the stable molding torque reference value by 20% (solid line 3). In other words, a result of reaching (decreasing) 80% of the stable molding torque reference value was obtained. Further, the 60th molding cycle was the last molding cycle in which a good product was molded.

Thus, in Example 1, it was confirmed by the above-described test molding that 80% of the second average rotational torque (stable molding torque reference value) is the set molding end value. In addition, after the supply of the resin material is stopped, a defective product with insufficient resin amount is not molded, and the first average rotational torque of the screw 16 is molded under the condition that the amount of the resin material held in the injection device is minimized. It was confirmed that it was a molding cycle (60th in the case of Example 1) that reached (decreased) 80% of the second average rotational torque of the latest five times (set number). Therefore, even in actual molding for producing a resin molded product, the object of the present invention can be achieved by setting the molding cycle that satisfies this condition as the final molding cycle.

In the average rotational torque comparison step, the present invention ends the molding cycle with the molding cycle in which the first average rotational torque is lower than the set molding end value as the final molding cycle. Therefore, in the first embodiment, the set molding end value may be set as 80% of the stable molding torque reference value.

In Example 1, the first average rotational torque of the screw 16 is confirmed to be slightly fluctuated due to factors that cannot be avoided. However, the difference in the first average rotational torque for each molding cycle before stopping the supply of the resin material 14a is not large and shows a relatively stable value, and the set molding end value (stable molding torque reference value). There is no fluctuation to reach 80%). In the first embodiment, since the rotation torque average value (first average rotation torque), not the rotation torque itself of the screw 16 in the weighing process, is compared with the stable molding torque reference value, the change in the rotation torque of the screw 16 varies. However, the possibility of erroneous detection as in the material detection method of the injection molding machine of Patent Document 1 is reduced.

In Example 1, the set molding end value is set based on the stable molding torque reference value (second average rotational torque). The stable molding torque reference value (second average rotational torque) is a value obtained by averaging again the first average rotational torque in the molding cycle of the set number of consecutive times (last five times). Therefore, as shown by the solid line 3 in FIG. 6 and the like, the set molding end value of each molding cycle based on the stable molding torque reference value (second average rotational torque) is the first average of the same molding cycle for all three candidates. The fluctuation is suppressed more than the rotational torque. As a result, the possibility of erroneous detection as in the material detection method of the injection molding machine of Patent Document 1 is further reduced.

Further, in a weighing process of a certain molding cycle, a large variation in rotational torque occurs due to an unexpected sudden factor, and even if a variation occurs in the first average rotational torque of the molding cycle, a plurality of first averages By averaging the rotational torque and calculating the stable molding torque reference value (second average rotational torque), the influence of the fluctuation can be suppressed. The stable molding torque reference value calculated in this way is the moving average of the rotational torque of the screw calculated as one time series for one metering step of a certain molding cycle, as in the method of stopping the purge operation in Patent Document 2. It is clear that the reliability is higher than the value.

Furthermore, in Example 1, the second average rotational torque is calculated from the first average rotational torque in the last five consecutive molding cycles, and the stable molding torque reference value is set each time. Therefore, as shown in FIG. 6, the set molding end value based on the stable molding torque reference value (second average rotational torque) in the change (decrease) in the first average rotational torque after the supply of the resin material 14 a is stopped. Changes immediately (follows down). In this way, by setting the latest stable molding torque reference value each time, it can occur even under conditions where good products are molded due to the influence of temperature changes in the environment in which molding is performed, temperature changes in the injection molding machine, etc. Thus, the influence of fluctuations in the first average rotational torque and the second average rotational torque (stable molding torque reference value) can be suppressed, and the desired timing of the molding cycle can be ended.

As described above with reference to FIG. 6, the setting molding end value, the selection method, and the number of times are changed for the setting molding end value and the molding cycle selection method and number of times for calculating the second average rotational torque. It is only necessary to obtain an appropriate set value that can determine the timing at which the defective amount of the resin material is not molded and the holding amount of the resin material in the injection apparatus is minimized by performing the test molding or the like. Further, the first average rotational torque, the second average rotational torque, and the setting end value may be displayed as rotational torque values instead of% display.

However, in view of the high reliability of the stable molding torque reference value in the present invention, the setting end value is a test molding rather than setting the rotational torque value itself of the first average rotational torque obtained by the test molding or the like as the setting value. The first average rotational torque obtained by the above method is set to a setting value associated with the second average rotational torque (stable molding torque reference value) obtained by the same test molding or the like (for example, as in the first embodiment, the setting is completed) It is more preferable that the value be a ratio (%) that decreases from the stable molding torque reference value.

Next, a method for terminating a molding cycle of an injection molding machine according to Embodiment 2 of the present invention will be described with reference to FIG. Also in the second embodiment, it is assumed that the injection molding machine having the inline screw injection device 1 described above is used. Further, the second embodiment differs from the first embodiment only in the timing at which the second average rotational torque calculating step and the average rotational torque comparing step of the screw 16 are performed in the selected molding cycle. Since the other points are basically the same as those in the first embodiment, the same reference numerals as those in the first embodiment are used for the same components, and redundant description is omitted.

In Example 2, as in Example 1, the predetermined number of times that the first average rotational torque calculation step is not performed is five, and a good product can be molded from the sixth molding cycle B1. In the second average rotational torque calculation step, the molding cycle selection method and the number of times for calculating the second average rotational torque are also set to five consecutive times as in the first embodiment.

In Example 2, as in Example 1, the first average rotational torque calculation step is performed in each of the five consecutive B molding cycles from the sixth molding cycle B1 in which a good product can be molded. Further, the second average rotational torque is calculated and the stable molding torque reference value TB is set substantially simultaneously with the completion of the measurement process of the tenth molding cycle B5.

In the second embodiment, unlike the first embodiment, the first average rotational torque calculation step is performed in each molding cycle of five consecutive C molding cycles from the eleventh molding cycle C1. Further, the second average rotational torque is calculated and the stable molding torque reference value TC is set substantially simultaneously with the completion of the metering step of the fifteenth molding cycle C5. Further, the first average rotational torque of each molding cycle (C1 to C5) of the C molding cycle is compared with the stable molding torque reference value TB set in the previous B molding cycle (average rotational torque comparison step).

Furthermore, in Example 2, the first average rotational torque calculation step is performed in each molding cycle of the five consecutive D molding cycles from the 16th molding cycle D1, and the second average rotational torque calculation step is performed. Make it. Further, the first average rotational torque of each molding cycle (D1 to D5) of the D molding cycle is compared with the stable molding torque reference value TC set in the previous C molding cycle.

As described above, in the second embodiment, a plurality of (5 consecutive) molding cycles selected in the second average rotational torque calculation step are set as one set, and a stable molding torque reference value is set for each set. In the average rotational torque comparison step, the first average rotational torque of each set of molding cycles is compared with a stable molding torque reference value set in the immediately preceding one set.

The form of Example 2 is suitable for molding in which the first average rotational torque of the screw 16 does not vary and the first average rotational torque is relatively stable as compared with the molding of Example 1. In particular, when the amount of metering resin required for one molding cycle is small with respect to the size of the injection device, and a non-defective product can be molded in about 5 to 6 molding cycles even if the material supply is stopped, the second average By reducing the number of molding cycles selected in the rotational torque calculation step (2 to 3 times), the fluctuations in the first average rotational torque and the second average rotational torque can be controlled with a relatively simple control compared to the first embodiment. Even if it occurs, this can be reflected. The setting molding end value employed in the average rotational torque comparison step, the molding cycle selection method and the number of times for calculating the second average rotational torque, and the like are the same as those in the first embodiment, and the description thereof will be omitted.

The present invention can be implemented in various forms without being limited to the above embodiment. For example, in Example 1 and Example 2, the first average rotational torque calculation step and the second average rotational torque calculation step are performed from the sixth molding cycle B1 in which a good product can be molded. However, the present invention is not limited to this. It is not something. For example, after the molding is started, the second average rotational torque calculation step is performed a plurality of times selected from an arbitrary molding cycle, and then the calculated stable molding torque reference value is stored in the control device, and another arbitrary From this molding cycle, the average rotational torque comparison step may be performed using this stable molding torque reference value.

In Example 1 and Example 2, the first average rotational torque calculation step and the second average rotational torque calculation step are performed in five consecutive molding cycles from the sixth molding cycle B1 in which a good product can be molded. However, the present invention is not limited to this. For example, from one continuous molding cycle, a plurality of molding cycles may be selected, such as the first and third cycles. In addition, for example, a plurality of molding cycles may be selected by skipping a plurality of times such as the fifth and the tenth from 50 consecutive molding cycles. By selecting such a molding cycle, it is possible to ensure the stability of the value of the second average rotational torque without increasing the load on the control device.

On the other hand, an injection device of an injection molding machine includes a pre-plastic injection device having a configuration different from that of an inline screw injection device. The pre-plastic injection device has a configuration in which a plasticizing cylinder for plasticizing a resin material and an injection cylinder for injecting and filling a resin material are connected on the nozzle side. The pre-plastic injection device is configured to store a resin material plasticized by a plasticizing cylinder having a built-in rotating screw in a storage part in the injection cylinder connected to the front of the plasticizing cylinder through a resin flow path. Has been. In addition, the pre-plastic injection device, after completion of the metering process, advances the plunger that is slidable in the longitudinal direction in the injection cylinder so that the resin material stored in the storage portion is injected and filled into the mold. It is configured. Thus, the pre-plastic injection device is greatly different from the configuration of the in-line screw injection device in that the plasticizing cylinder and the injection cylinder are independent. In the first and second embodiments, the description has been made on the assumption of an injection molding machine having an inline screw type injection device. However, the present invention is not limited to this, and the present invention is also implemented in an injection molding machine having a pre-plastic injection device. Is possible.

DESCRIPTION OF SYMBOLS 1 In-line screw type injection apparatus 10 Resin flow path 13 Nozzle 14 Material supply part 14a Resin material 15 Heating barrel 15a Heating means 15b Storage part 16 Screw 16a Flight 17 Screw head 18 Check ring

Claims

Molding of an injection molding machine having an injection device that rotates a screw in a heating barrel and plasticizes the resin material supplied into the heating barrel from the rear of the screw while flowing toward the front of the screw A cycle end method,
A first average rotational torque calculating step of calculating a first average rotational torque of the screw in a metering step of storing the plasticized resin material up to a set amount in the storage unit of the injection device in one molding cycle;
From the arbitrary molding cycle, the first average rotational torque calculation step is performed in each of a plurality of selected molding cycles, and the plurality of selected molding cycles are determined from each of the obtained first average rotational torques. And calculating a second average rotational torque at the same time, and setting the second average rotational torque as a stable molding torque reference value;
An average rotational torque comparison step of comparing the first average rotational torque in any one molding cycle after setting the stable molding torque reference value with the stable molding torque reference value;
Have
In the average torque comparison step, the first molding torque reaches a set molding end value from the stable molding torque reference value, or a molding cycle in which the first molding torque falls below the set molding end value is defined as a final molding cycle. A method for terminating a molding cycle of an injection molding machine, wherein the molding cycle is terminated in the cycle.
2. The molding cycle end method for an injection molding machine according to claim 1, wherein the first average rotational torque calculation step is not performed in a predetermined number of molding cycles after the start of molding.
From any molding cycle, the first average rotational torque calculation step is performed for each molding cycle,
From the arbitrary molding cycle, start the second average rotational torque calculation step for each molding cycle,
In the average rotational torque comparison step, the first average rotational torque in the molding cycle immediately after the molding cycle in which the stable molding torque reference value is set in the second average rotational torque calculation step is set in the immediately preceding molding cycle. The molding cycle end method of the injection molding machine according to claim 1, wherein the method is compared with the stable molding torque reference value.
The selected plurality of molding cycles in the second average rotational torque calculation step is set as one set, and the stable molding torque reference value is set for each set, and in the average rotational torque comparison step, the one set The molding cycle end method for an injection molding machine according to claim 1 or 2, wherein the first average rotational torque of each molding cycle is compared with the stable molding torque reference value set in the immediately preceding one set. .
5. The stable molding torque reference value is set in the second average rotational torque calculation step every time the molding cycle is restarted after a stop operation including a temporary stop of the molding cycle. 6. A molding cycle end method for an injection molding machine according to claim 1.