JP5216313B2 - Control method of online blending type injection molding machine - Google Patents

Description

  The present invention relates to a continuous plasticizing type injection molding machine (hereinafter referred to as an injection molding machine) in which a continuous plasticizing device and an injection device are connected via an accumulator device that temporarily accumulates a plasticized molten resin (hereinafter referred to as plasticized resin) Online blend type injection molding machine), and in particular, the online blend type injection molding machine that controls the actual molding cycle time for each shot to be close to the preset molding cycle time by adjusting the raw material supply amount of the feeder. Relates to the control method.

  Conventionally, in order to improve the efficiency of the injection molding machine, the plasticizing device and the injection device are separated, and an accumulator is provided between them, and the resin plasticized by the plasticizing device is stored in the accumulator, and intermittently from this accumulator. An on-line blend type injection molding apparatus that increases the operating rate of a plasticizing apparatus by supplying plasticizing resin to the injection apparatus is already known.

  In general, the continuous plasticizing type injection molding apparatus shows a tendency that the discharge pressure of the plasticizing apparatus becomes high in the metering step of supplying the plasticized resin from the accumulator to the injection apparatus. This is because the resin pressure loss between the accumulator and the injection device is added and the mechanical friction loss for retracting the injection plunger is added compared to the process of simply storing the plasticized resin in the accumulator. doing. The fluctuation in the discharge pressure of this plasticizer causes uneven plasticization, and when the discharge pressure rises abnormally, vent-up occurs, resin leaks from the joints of the open / close valve and resin flow path, etc. Furthermore, since the thrust load of the plasticizing screw becomes large, there arises a problem that it is necessary to increase the rigidity of the screw driving device.

  In order to prevent an increase in the discharge pressure of the plasticizer, the resin pressure loss and the mechanical friction loss may be compensated by positively retracting the injection plunger during measurement. However, if the injection plunger is retracted positively, the resin pressure in the injection cylinder may be reduced to a negative pressure. Even if the injection plunger is retracted by a predetermined amount, a predetermined amount of plasticized resin is placed in the injection cylinder. Cannot be weighed, and the molded product becomes a so-called short shot with an insufficient amount of resin.

  To solve these problems, a continuous plasticizing device for synthetic resin material, an accumulator device comprising a cylinder and a plunger connected to the outflow passage of the continuous plasticizing device, and an open / close valve in the outflow passage of the accumulator device An injection device composed of an injection cylinder and an injection plunger connected via an outlet, and the outflow passage of the continuous plasticizing device can communicate with the outflow passage of the accumulator device even when the plunger of the accumulator device is in the extrusion limit position. A continuous plasticizing injection molding method using a configured continuous plasticizing injection molding device, wherein a metering step of causing a predetermined amount of plasticizing resin to flow into an injection cylinder by retreating the injection plunger while advancing the plunger of the accumulator device In order to maintain the discharge pressure of the continuous plasticizer within a predetermined range, In addition to causing the operation and retraction of the injection plunger, the plasticizing resin continues to be supplied to the injection cylinder even after the injection plunger retracts by a predetermined amount and substantially stops, and the resin pressure in the injection cylinder reaches a predetermined value or more. Then, the method of closing an on-off valve and shifting to an injection process has been proposed. (Patent Document 1)

JP-A-5-131509

  By the way, when continuous molding is performed with an on-line blend type injection molding machine, not only timer settings such as the injection timer (TR1) and cooling timer (TR3) but also the raw material supply amount, that is, the feed amount and the molding quality amount are large in the molding cycle. Affect. If the feed amount is too small, the molding cycle becomes long, and if the feed amount is too large, the raw material in the resin accumulator device cannot be completely processed for each shot, and overflow occurs. Therefore, it is necessary to set an appropriate value for the feed amount in accordance with the target molding cycle and molding quality amount. For example, the feed amount is calculated and set by the following equation.

(Feed amount calculation example)
Feed amount appropriate value (kg / h) = (molding quality amount (kg) / setting cycle (sec)) × 3600 (sec)
If the injection timer (TR1) or cooling timer (TR3) timer settings are changed during molding with the feed amount calculated using the above formula, the setting cycle will fluctuate, so the feed amount must be recalculated and re-input each time. was there.

  In addition, when the feed amount is set to be smaller than the actually required feed amount, the actual cycle becomes long and easy to notice, but when the feed amount is set to be large, it is difficult to notice. This is because if the feed amount is an appropriate value, the timeout of the cooling timer (TR3) and the metering time are almost equal, but if the feed amount is set to a large value, the amount of raw material stored in the resin accumulator device increases, so the metering time Is also shortened. Even if the metering time is shortened, the cycle is not completed unless the cooling timer (TR3) times out. Since the continuous molding is performed according to the set timer, it seems to be stable in the molding cycle and becomes difficult to notice. However, if this situation continues for a long time, the amount of raw material stored in the resin accumulator device gradually increases, and a large amount of raw material stays in the resin accumulator device, and eventually overflows. For this reason, the operator must constantly monitor the monitoring data of the molding cycle and the metering time and continue to adjust the feed amount, and this monitoring and adjustment work is a heavy burden for the operator (operator) who is operating the injection molding machine. It was. Moreover, in the above-mentioned patent document 1, there was no suggestion which solves the problem in such continuous molding.

The present inventors have, as a result of various investigations and research to solve the above problems, when the actual molding cycle time per shot is different from the set molding cycle time which is set in advance, a raw material feed rate of the feeder It has been found that the above-mentioned problems can be solved by automatically adjusting.
Accordingly, an object of the present invention, if different from actual molding cycle time set molding cycle time which is set in advance, a control method for online blend injection molding machine is controlled so as to automatically adjust the raw material supply amount of the feeder It is to provide.

In order to achieve the above object, a control method of an on-line blend type injection molding machine according to the present invention comprises a screw rotation that rotates a screw that melts and kneads a synthetic resin material charged in a heating cylinder and plasticizes it at a predetermined speed. A continuous plasticizer for the synthetic resin material comprising a feeder for continuously supplying and controlling a required amount of the synthetic resin material into the heating cylinder, and a plasticized resin extruded from the continuous plasticizer. A cylinder chamber connected to a leading outlet, a first plunger provided in the cylinder chamber so as to be capable of advancing and retracting, and an accumulator device having a first drive means for driving the first plunger forward and backward, and the accumulator device being extruded from the accumulator device An injection cylinder chamber having a plastic resin inflow port connected to a flow path for guiding the plasticized resin, and formed in communication with the injection direction of the injection cylinder chamber An injection nozzle section, a second plunger provided in the injection cylinder chamber so as to be able to advance and retract, and a second drive means for driving the second plunger forward and backward, and driving the second plunger in the injection direction from the injection nozzle. A control method for continuously performing injection molding using an on-line blend type injection molding machine having an injection device for injecting a plasticized resin into a mold cavity, the sum of an injection timer, a cooling timer, and an interval timer The set molding cycle time consisting of the timer set value and the mold opening / closing time monitor value is compared with the actual molding cycle time, and if there is a difference between the two, the raw material supply amount of the feeder is adjusted. .

  According to the present invention, since the feed amount is constantly monitored and automatically corrected during operation of the online blend type injection molding machine, the operator is freed from the work of sticking to the injection molding machine and adjusting the feed amount. It becomes.

  Hereinafter, a preferred example based on the embodiment of the present invention will be described in detail with reference to FIGS.

  FIG. 1 shows a longitudinal sectional view of main components of a general online blend type injection molding machine to which the present invention is applied. In FIG. 1, reference numeral 10 denotes a twin-screw extruder constituting the above-described plasticizing device, and a main synthetic resin material, for example, polypropylene (PP), is provided from a main feeder device MF disposed above the twin-screw extruder. It is supplied to the hopper 10A according to the rotation speed of the feeder motor M. On the left side, a sub-feeder device SF is arranged, and an auxiliary molding material such as talc is similarly supplied to the hopper 10A according to the rotation speed of the feeder motor M. The molding material supplied from the hopper 10A into the heating cylinder 10C of the twin-screw extruder 10 is melted, kneaded and plasticized by two screw shafts 10B joined via a gear box by a motor 10D. VT1 and VT2 are an open vent and a vacuum vent, respectively.

  An accumulator 12 formed integrally with the heating cylinder 10C is disposed on the left end side of the biaxial extruder 10. In the upper and lower cylinder chambers 12A, 12B of the accumulator 12, a plunger tip 12C provided at the lower end portion of the plunger 12D is disposed. The upper end portion of the plunger 12D is coupled to the piston PS1, and the piston PS1 is connected by the hydraulic cylinder device 12E. It can move up and down.

  As shown by the arrows in the figure, the molten resin, that is, the plasticized resin, flows into the cylinder chamber 12B from the left end portion of the twin-screw extruder 10 through the outlet FG1. Since the discharge pressure of the twin-screw extruder 10 is relatively low, the piston PS is moved upward in order to keep the resin pressure when the plasticized resin flowing into the cylinder chamber 12B flows in low. During this time, the valve VL1 provided at the lower part of the accumulator 12 is closed. Although not shown, a load cell is disposed in the middle of the plunger 12D, and the piston PS1 is hydraulically controlled by the load cell so that the resin pressure in the cylinder chamber 12B is within a predetermined range.

  Reference numeral 14 is an injection device, and when the valve VL1 is opened, an injection cylinder formed on the injection side of the injection device 12 through the inflow port FG2 is used to store the plasticized resin accumulated in the cylinder chamber 12B. Accept within 14A. That is, during the metering process, plasticizing resin is supplied from the inlet FG2 into the injection cylinder 14A, whereby the cone-shaped plunger tip 14C provided at the left end of the plunger 14D moves backward to the right. In that case, the piston PS2 is retracted by supplying and discharging pressure oil to the injection cylinder device 14E so that the resin pressure in the cylinder chamber 12B and the injection cylinder 14A, that is, the discharge pressure of the twin-screw extruder 10 does not become higher than a predetermined value. It is designed to move. During the metering operation, the valve VL2 is closed and opened after the metering is completed, and the molten resin in the injection cylinder 14A moves the piston PS2 to the left to form the mold cavity formed in the mold device 16 via the nozzle NZ. It is injected into (not shown). In the mold apparatus 16, the supply and discharge of the cooling water is controlled through an on-off valve set with a timer (not shown).

FIG. 2 is a conceptual block diagram for explaining the gist of the present invention. In FIG. 2, the reference symbol MC indicates the main body side of the online blend injection molding machine, and the reference symbol CTR generates a shot operation command signal group SG that commands continuous operation of the online blend injection molding machine MC. Reference symbol PFL indicates the main part of the flow of processing by a control program provided in the control device.
That is, in the process flow PFL of the program stored in the program memory PGM, the difference between the set molding cycle time (SCT) preset as a parameter in the data memory DAM and the actual molding cycle time (RCT) in the actual shot is It is calculated by the central processing unit CPU, and the feed amount is calculated and adjusted according to the value. In that case, adjustment of the feed amount is performed by designating the number of rotations of the motor M of the main feeder MF and the sub-feeder SF in FIG. 1 each time.

FIG. 3 is a flowchart for explaining the PFL in more detail.
Now, it is confirmed that the continuous molding operation is possible, and the total number Z of molded products to be manufactured is set as one of the parameters. When a control program start command is given in step ST0, first, in step ST1. Index i is set to 1. Next, in step ST2, it is determined whether or not the value of the index i is 1. If the result is affirmative YES, the first shot operation is commanded. Next, in step ST6, the parameters P1, P2 and the data at the previous shot operation are taken from a predetermined area of the data memory DAM in the control device.

  Here, the parameter P1 is an allowable time (sec) when an actual molding cycle time (hereinafter referred to as an actual cycle RCT) is regarded as a set molding cycle time (hereinafter referred to as a setting cycle SCT). For example, when P1 = 0.1, if the actual cycle is within an error range of 0.1 sec with respect to the set cycle, it is considered that the actual cycle RCT = set cycle SCT.

The parameter P2 is an allowable time value (%) with respect to the difference (absolute value) between the monitoring value of the measuring time (hereinafter referred to as the actual measuring time RT) and the cooling timer (TR3).
For example, in the case of actual weighing time RT <cooling timer TR3,
| (1− (RT / TR3)) | × 100%> P2
If it becomes, correct the feed amount.

That is, in step ST7, it is determined whether or not the actual cycle RCT> the set cycle SCT. If YES, a feed amount correction command CN0 is given in step ST8. The corrected feed amount Q ′ (kg / h) corresponding to this command CN0 is
Q ′ (kg / h) = Q + (Q × Qrev)
It is. here,
Qrev (feed amount correction rate) = (actual cycle RCT−set cycle SCT) / set cycle SCT
Is defined.

When the determination in step ST7 is negative NO, it is further determined in step ST9 whether or not the actual cycle RCT is equal to the set cycle SCT. If the determination is step YES, the actual measurement time RT is further set to the cooling timer setting time TR3 in step ST10. It is determined whether or not the value has been exceeded. If NO in ST9 and ST10, it is confirmed in step ST11 that RCT <SCT, and a feed amount correction command CN1 is given in step ST12. The corrected feed amount Q ′ (kg / h) corresponding to the command CN1 is the same as the command CN0,
Q ′ (kg / h) = Q + (Q × Qrev)
It is. here,
Qrev (feed amount correction rate) = (actual cycle RCT−set cycle SCT) / set cycle SCT
Is defined.

On the other hand, when the determination in step ST10 is YES, in ST13,
| (1− (RT / TR3)) | × 100% <= P2
It is determined whether or not. If it is equal to or less than P2, that is, within an allowable value, a command without correcting the feed amount is given in ST15. In ST13,
| (1− (RT / TR3)) | × 100%> P2
If this is the case, a feed amount correction command CN2 is given in ST14. In this command CN2, the corrected actual cycle time (RCT ′) is newly defined as follows. That is,
Corrected actual cycle time (RCT ′) = actual cycle RCT−cooling timer set value TR3 + actual weighing time RT
Then, Qrev (feed amount correction rate) = (corrected actual cycle RCT′−set cycle SCT) / set cycle SCT
The corrected feed amount Q ′ (kg / h) is
Q ′ (kg / h) = Q + (Q × Qrev)
It becomes.

When the correction of the feed amount is commanded in each of the steps ST8, ST12, ST14, the next shot operation based on the feed amount corrected in the step ST16 is commanded. Further, since the feed amount correction is not commanded in ST15, the shot operation of ST16 is commanded with the same feed amount as that at present.
Next, in step ST17, the index i is incremented by 1 to become i + 1. Next, in ST2, the determination is negative, so in step ST4, it is determined whether or not the total number of molded articles Z has been reached. In the case of negative NO in ST4, in ST6, the parameters and each data by the previous shot operation are fetched from the data memory. Thereafter, the same process as described above is continued. In ST4, when the number i of shot operations reaches the total number Z of molded products, the end of the shot operation is commanded in step ST5, and the continuous molding control program is terminated.

Next, a more specific example of calculating the feed amount in route 1 to route 4 without correcting or correcting each feed amount shown in FIG. 2 will be described.
As a molding example, a molded product having a mass of 680 g is set cycle SCT = 60.0 sec, that is, injection timer TR1 = 7.0 sec, cooling timer TR3 = 35.0 sec, interval timer INT = 8.0 sec, mold opening time monitor Molding is performed under the conditions of value = 5.5 sec and mold closing time monitor value 4.5 sec. Parameters P1 = 0.05 (sec) and P2 = 5.0 (%).

(A) Feed amount calculation example in the case of route 1, that is, set cycle SCT <actual cycle RCT:
In the mode for manually setting the feed amount, the feed amount is automatically calculated during molding with the feed amount set value Q = 40.0 kg / h, the actual cycle RCT = 61.2 sec, and the metering time RT = 36.2 sec. Switched.
As described above, P1 = 0.05 (sec) and P2 = 5.0 (%). Therefore,
| RCT-SCT | = | 61.2-60.0 | = 1.2> P1
Therefore, the actual cycle RCT> the set cycle SCT. on the other hand,
| (1− (actual metering time RT / cooling timer TR3)) | × 100 (%) = | (1- (36.2 sec / 35.0 sec)) | × 100 = | (1-1.34) | × 100 = 3.4 (%) <P2
In this case, the feed amount correction rate (Qrev) = (actual cycle RCT−setting cycle SCT) / setting cycle SCT = (61.2−60.0) /60.0=0.02
Therefore, the corrected feed amount (Q′kg / h) = Q + (Q × Qrev) = 40.0 + (40.0 × 0.02) = 40.8
It is.

(B) Feed amount calculation example 1 in the case of route 2, that is, set cycle SCT = actual cycle RCT:
In the above molding example, the actual cycle RCT during molding in the mode in which the feed amount is calculated as white motion is 59.98 sec. At this time, Q = 41.9 kg / h, actual measurement time RT = 33.4 sec
Further, as described above, P1 = 0.05 (sec) and P2 = 5.0 (%). Therefore,
| RCT-SCT | = | 59.98-60.0 | = | −0.02 | <P1
Therefore, it is considered that the actual cycle RCT = the set cycle SCT. on the other hand,
| (1− (actual weighing time RT / cooling timer TR3)) | × 100 (%) = | (1− (33.4 / 35.0)) | × 100 = (1−0.954) × 100 = 4.6% <P2
Therefore, the corrected feed amount is not calculated, and the previous feed amount (41.9 kg / h) is maintained and continued.

(C) Feed amount calculation example 2 in the case of route 3, that is, set cycle SCT = actual cycle RCT:
In the above molding example, the actual cycle RCT during molding in the mode for automatically calculating the feed amount is 59.98 sec.
At this time, Q = 43.0 kg / h and actual measurement time RT = 31.93 sec.
Further, as described above, P1 = 0.05 (sec) and P2 = 5.0 (%).
In this case, | RCT-SCT | = | 59.98-60.0 | = | −0.02 | <P1
Therefore, it is considered that the actual cycle RCT = the set cycle SCT. But,
| (1- (RT / TR3)) | × 100 (%) = (1- (31.93 / 35.0)) × 100 = (1−0.912) × 100 = 8.8 (%)> P2
Therefore, the corrected feed amount is calculated.
Corrected actual cycle time (RCT ′) = actual cycle RCT−cooling timer TR3 + actual weighing time RT
= 60.0-35.0 + 31.93 = 56.93 sec
It is. Therefore,
Feed amount correction rate (Qrev) = (corrected actual cycle RCT′−setting cycle SCT) / setting cycle SCT = (56.93−60.0) × 60.0 = −0.51
Also, the corrected feed amount (Q′kg / h) = Q + (Q × Qrev)
= 43.0 + (43.0 × (−0.51)) = 43.0−2.2 = 40.8.

(D) Feed amount calculation example in the case of route 4, that is, set cycle SCT> actual cycle RCT:
In the above molding example, the injection timer (TR1) was changed from 7.0 sec to 8.5 sec during molding in the mode for automatically calculating the feed amount. The feed amount output immediately before the setting change is 40.8 kg / h, the actual cycle RCT is 60.0 sec, and the actual weighing time RT is 33.4 sec.
Setting cycle SCT = injection timer TR1 + cooling timer TR3 + interval timer INT + mold opening time + mold closing time = 8.5 + 35.0 + 8.0 + 5.5 + 4.5 = 61.5 sec> actual cycle RCT
It is. Further, as described above, P1 = 0.05 (sec) and P2 = 5.0 (%).
In this case, | RCT-SCT | = | 60.0-61.5 | = | −1.5 |> P1
Therefore, it is considered that the actual cycle RCT <the set cycle SCT. further,
| (1- (RT / TR3)) | × 100 (%) = (1- (33.4 / 35.0)) × 100 = (1−0.954) × 100 = 4.6 (%) < P2
It is.
That is, the allowable time value for P2 is smaller than the value of the set parameter P2, but the allowable time value for P1 is larger than the value of the set parameter P1, so the corrected feed amount is calculated.
Here, the feed amount correction rate (Qrev) = (actual cycle RCT−setting cycle SCT) / setting cycle SCT = (60.0−61.5) /61.5=−0.024
It is. Therefore, the corrected feed amount (Q′kg / h) is
Q′kg / h = Q + (Q × Qrev) = 40.8 + (40.8 × (−0.024))
= 40.8-0.995 = 39.805 (≈ 39.8 kg / h)
It becomes.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to those illustrated, and various modifications can be made by those skilled in the art. For example, the drive means of the accumulator device of an online blend type injection molding machine or the advance / retreat drive on the injection side can be configured using an electric servo motor .
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[1] A screw rotating motor that rotates a plasticizing plastic resin material that has been charged into a heating cylinder, plasticized by melting and kneading, and a predetermined amount of the synthetic resin material continuously into the heating cylinder. A continuous plasticizing device for the synthetic resin material consisting of a feeder unit for supply control, a cylinder chamber connected to an outlet for guiding the plasticized resin extruded from the continuous plasticizing device, and a cylinder chamber connected to the cylinder chamber so as to be able to advance and retract. An accumulator device having a first plunger and a first drive means for driving the first plunger back and forth, and an inflow port for the plasticized resin connected to a flow path for guiding the plasticized resin extruded from the accumulator device. An injection cylinder chamber, an injection nozzle portion formed in communication with the injection direction of the injection cylinder chamber, a second plunger provided in the injection cylinder chamber so as to be movable forward and backward, and the same Online blending type injection molding having an injection device that includes a second driving means for driving the plunger back and forth and driving the second plunger in the injection direction to inject plasticized resin into the mold cavity from the injection nozzle This is a control method for continuous injection molding using a machine, where the set molding cycle time consisting of the timer setting value and the mold opening / closing time monitor value is compared with the actual molding cycle time, and there is a difference between the two Is a control method for an on-line blend type injection molding machine that adjusts the raw material supply amount of the feeder so that the actual molding cycle time becomes equal to the set molding cycle time.

It is a longitudinal cross-sectional view of the main components of a general online blend type injection molding machine to which the present invention is applied. It is a conceptual block diagram explaining the summary of this invention. It is a flowchart for demonstrating the processing method of the control program by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Twin screw extruder 12 Accumulator 14 Injection apparatus 16 Mold apparatus MF Main feeder SF Sub feeder M Feeder motor

Claims (1)

A screw rotation motor that rotates a plasticizing plastic resin material that is melted, kneaded and plasticized in a heating cylinder at a predetermined speed, and continuously supplies and controls a required amount of the synthetic resin material into the heating cylinder. A continuous plasticizing device for the synthetic resin material comprising a feeder portion, a cylinder chamber connected to an outlet for guiding the plasticized resin extruded from the continuous plasticizing device, and a first chamber that is capable of moving forward and backward in the cylinder chamber An accumulator device having a plunger and a first drive means for driving the first plunger back and forth, and an injection cylinder having a plastic resin inlet connected to a flow path for guiding the plastic resin extruded from the accumulator device Chamber, an injection nozzle portion formed in communication with the injection direction of the injection cylinder chamber, a second plunger provided in the injection cylinder chamber so as to be able to advance and retreat, and the second plunger An on-line blend type injection molding machine comprising a second drive means for driving the plunger back and forth, and having an injection device for injecting plasticized resin into the mold cavity from the injection nozzle by driving the second plunger in the injection direction A control method for continuously performing injection molding using
When the set molding cycle time consisting of the timer setting value and the mold opening / closing time monitor value, which is the sum of the injection timer, the cooling timer, and the interval timer, is compared with the actual molding cycle time. A control method for an on-line blend type injection molding machine that adjusts the raw material supply amount of the feeder.

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