JPS63150632A - Method for measuring consumed resin weight for injection molding machine - Google Patents

Abstract

PURPOSE:To accurately measure the weight of consumed resin by detecting the position of a screw and calculating the consumption weight of resin injected actually by an injection molding machine from the quantity of the movement of the screw. CONSTITUTION:Resin 2 from a hopper 1 falls in a plasticization cylinder 2 and the screw 6 is pushed back. An injection cylinder 4 provided to the rear end of the plasticization cylinder 3 applies injection force to the screw 6, which injects the resin 2 into a metallic mold 7 from a nozzle part 3a. The position of the screw 6 is detected by a rotary encoder 9. A CPU 11 computes the weight of the resin consumed for one-time injection from the output of the rotary encoder 9, the external diameter of the screw, and the specific gravity of the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the weight of resin consumed in an injection molding machine.

[Conventional technology]

In an injection molding machine, a screw inserted into a plasticizing cylinder is rotated, the screw is moved back, the amount of resin required for the molded product is measured, and the resin is injected into the mold by moving the screw forward. Chilled with a machine that produces molded products.

In this type of injection molding machine, it is necessary to accurately grasp the weight of resin injected from the injection molding machine, that is, the weight of consumed resin, in order to control costs and plan material requirements.

Conventionally, the weight of resin consumed by an injection molding machine has been measured by installing a measuring device such as a resin weighing meter somewhere along the path from the resin silo to the end of the injection molding machine.

[Problem that the invention seeks to solve]

With such a method of measuring the weight of consumed resin using a conventional measuring device, it is not possible to accurately measure the weight of consumed resin actually injected from an injection molding machine.

This is because the resin in the area from the mounting position of the measuring instrument to the nozzle part of the plasticizing cylinder of the injection molding machine (for example, the resin in the hole and the resin in the plasticizing cylinder) remains as an uncertain element. It is from. Furthermore, there is a drawback that a dedicated measuring device is required for measuring the weight of consumed resin in addition to the equipment originally provided in the injection molding machine. Furthermore, the conventional method has the disadvantage that it is not possible to separate and measure the weight of consumed resin into a plurality of categories.

An object of the present invention is to provide a method that can accurately measure the consumed weight of resin injected from an injection molding machine.

Another object of the present invention is to provide a method for measuring the weight of resin consumed in an injection molding machine using equipment such as a screw position detector and an arithmetic control unit that are originally provided in the injection molding machine. It is in.

Still another object of the present invention is to provide a method for measuring the weight of consumed resin by dividing it into a plurality of ranges.

[Means for solving problems]

The present invention is used in an injection molding machine that measures the resin necessary for a molded product by rotating a screw inserted into a plasticizing cylinder, moves the screw backward, and injects the resin by moving the screw forward. One of the methods for measuring resin weight is to calculate the screw movement amount t in one injection from the screw position, and to calculate the screw movement amount t, preset screw outer diameter, and resin specific gravity ρ.
The method includes a step of determining the resin weight q consumed in one injection, and a step of integrating the resin weight q to determine the total consumed resin weight Q (=Σq).

Another aspect of the present invention is a step of determining the screw movement amount t in one injection from the screw position, a step of calculating the total screw movement amount L (=Σl) by integrating the screw movement amounts t, and a step of calculating the total screw movement amount L (=Σl). It includes the step of determining the total consumed resin weight Q based on the screw movement measurement and the preset screw outer diameter and resin specific gravity ρ.

Still another aspect of the present invention is a step of determining the amount of screw movement in 91 injections from the child fly position.

A step of calculating the resin weight q consumed in 91 injections from the screw movement amount t, preset screw outer diameter and resin specific gravity ρ, and determining which injection range the consumed resin weight q belongs to. and a step of accumulating the resin weight for each range injection to determine the consumed resin weight for each range injection.

〔Example〕

Hereinafter, nine embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 2, in an injection molding machine to which the present invention is applied, resin 2, which is a material from a hollow tube 1, falls into a plasticizing cylinder 3 due to its own weight. Injection cylinder 4
A screw 6 is rotated by a hydraulic motor 5 attached to the rear of the cylinder, whereby the resin 2 that has fallen is kneaded and sent along the groove to the tip of the cylinder. At this time, the resin 2 is heated by a heater (not shown) on the outer periphery of the plasticizing cylinder 3, and the frictional heat generated by the cross-wire action is added to the resin 2, so that the temperature rises from inside and becomes molten. As the molten resin 2 is stored at the tip of the plasticizing cylinder 3, the pressure of the resin 2 pushes the screw 6 back. By adjusting the amount of retraction, the amount of one injection can be measured. The above is the measurement process.

On the other hand, in the injection process, an injection force is applied to the screw 6 by the injection cylinder 4 attached to the rear end of the plasticizing cylinder 3, and the screw 6 acts as an injection plunger to inject the resin at its tip under high pressure. Then, the liquid is injected into the mold 7 from the nozzle part 3a.

The screw 6 and the piston 4a in the injection cylinder 4 are rotatable with respect to each other but do not move in the axial direction.

Fixed. A rack 8 is attached to the rear end of this piston 4a.
are connected to each other, and a binion 9a is arranged corresponding to the rack 8. A rotary encoder 9 as a screw position detector is incorporated in the binion 9a. The ie pulse is sent out in response to the rotation of the binion 9a.

The encoder 9 is connected to a central processing unit 11 via an interface 10 . The central processing unit 11 has a setting device 12 for setting the outer diameter D of the screw 6 (or the inner diameter of the plasticizing cylinder 3) and the specific gravity ρ of the resin 2 used, and stores values necessary for calculation and calculation results. Also connected are a memory 13 storing programs for causing the central processing unit 11 to perform processing, and a display 14 for displaying calculation results.

In addition, rotary encoder 9. interface 10, central processing unit 11. Setting device 12. It should be noted that the memory 13 and display 14 are originally provided to control the injection molding machine.

The mold 7 has a cavity 7a that is filled with the resin 2 to produce a molded product, and a sprue runner 7b that serves as a passage that guides the resin 2 from the nozzle portion 3a of the plasticizing cylinder 3 to the cavity 7a.

Also, when injecting, as shown in FIG.

There are cases in which the resin 2 is injected into the mold 7 and cases in which purging injection is performed to expel the resin 2 that has accumulated inside the plasticizing cylinder 3 before molding. usually.

/? - For non-injection, the nozzle part 3 of the plasticizing cylinder 3
Release the mold 7 from a to perform injection.

By the way, in an injection molding machine, the weight q of the resin 2 consumed in one injection is proportional to the amount of movement t of the screw 6. Koya, nukuru move it.

It is equal to the amount of screw retraction during metering, and is also equal to the amount of screw advancement during injection. More specifically, the resin weight q is expressed by a linear equation using the screw movement amount t, the screw outer diameter, and the resin specific gravity ρ.

q=ρ-D2t (1) The following invention aims to measure the weight of resin consumed in an injection molding machine by utilizing the relationship of equation (1).

Referring to FIG. 1, when performing injection molding with an injection molding machine, the screw outer diameter D and resin specific gravity ρ are input from the setting device 12, and the total consumed resin weight Q and groove 0 are initially set (
Step 101). The central processing unit 11 stores the screw outer diameter and the resin specific gravity ρ in the memory 13, and also stores the total consumed resin weight Q as O in the memory 13. Next, the central processing unit 11 reads the screw position lS at the start of measurement and the screw position t8 at the end of measurement via the screw position detector 9 and the interface 10 (step 10).
2) Store in the memory 13. The central processing unit 11 is
The difference between these screw positions t0 and t8 is taken to determine the screw movement amount t (=IAo-/-81) (step 103), and stored in memory 1) 13K. Next, the central processing bag M11 calculates the virtual resin weight q consumed in one injection from the screw outer diameter, resin specific gravity ρ, and screw movement amount t stored in the memory 13 using equation (1). Calculate step 1.04).

Store it in the memory 13. The central processing unit 11 has a memory 1
The total consumed resin N amount Q stored in A and the calculated resin weight qPl! : is added (step 105), and this addition result is stored in memory 1 again as a new total consumed resin weight Q.
Store in 3. The central processing unit 11 displays this total consumed resin weight Q on the display 1.1 (Stella 7'l O6
). The central processing bag υ11 is processed from step 102 to step 1
06 action.

The molding operation of the injection molding machine stops (Y in step 107).
By repeating the process up to ES), the total consumed resin weight Q, which is the sum of the resin weight q calculated in step 104, can be obtained as in a linear equation.

Q-Σq ・・・・・・・・・・・・ (2) In the above embodiment, in step 102, the screw position t0 at the start of measurement and the screw position t8 at the end of measurement are read. The screw position tS at the start of injection and the screw position lS at the end of injection may be read. In addition, in the above example, by calculating the amount q) of Hirotsuki, it is possible to obtain candy? Although we are trying to calculate the weight Q of resin for one injection, as shown in Figure 3, it is also possible to calculate the total weight Q of resin consumed after sequentially integrating the amount of screw movement t in one injection. good.

Referring to FIG. 3, when performing injection molding with an injection molding machine, the screw outer diameter and resin specific gravity ρ are input from the setting device 12, and O is initially set as the total screw movement amount (step 301). ). The central processing unit 11 stores the screw outer diameter and the resin specific gravity ρ in the memory 13, and also stores the total screw movement amount as O in the memory 13. Next, intermediate reading is performed (step 302), and the difference between these values is used to calculate the amount of cisfuryu movement t (step 303). The central processing unit 11 adds the calculated screw movement amount t to the total screw movement amount stored in the memory 13 (Stella7'304), and stores this addition result as a new candy screw movement amount in the memory 13 again. Store in. The central processing unit 11 repeats the operations from step 30.2 to step 304 until the molding operation of the injection molding machine is stopped (YES at step 305), thereby performing the operations at step 303 as in the linear equation. A total screw movement amount is obtained by integrating the calculated screw movement amount t.

L=Σl −・・・・・・・・・・・・ (3) Molding operation of the injection molding machine stops (YE in step 305)
S), the central processing unit 11 stores the screw outer diameter and resin specific gravity ρ stored in the memory 13.

Step 3: Calculate the total consumed resin weight Q consumed by the injection molding machine according to the 9th equation from the total screw movement amount and the total screw movement amount.
06) and stored in the memory 13.

12 ・・・・・・・・・・・・ (4) Q=ρ4
DL central processing unit 11 displays this total consumed resin mold ff1-Q on display 14 (step 307).

In the two embodiments described above, the total consumed resin weight Q is measured, but as described below, it may be measured separately for each range injection.

Referring to FIG. 4, in this embodiment, +'eiu consumed resin weight Q is determined depending on whether the whole mold injection or the ie-song injection is performed.

This is an example in which the consumed resin weight QD is divided into two categories: the consumed resin weight QD for total mold injection, and the consumed resin weight Q for total single-song injection. In this case, the screw outer diameter and resin specific gravity ρ are input from the setting device 12, and the consumed resin weight for total mold internal injection QD, total, ... - consumed resin weight for song injection Q
, and both O are initialized (step 401).
. Steps 402 to 404 are the same as steps 102 to 104 in FIG. 1, so their explanation will be omitted. Next, the central processing unit 11 determines whether the injection is full-mold injection or purging injection (step 405). This determination is made, for example, as follows. Namely.

The determination is made based on whether or not the nozzle portion 3a of the plasticizing cylinder 3 is in contact with the mold 7. Therefore, it is sufficient to attach a contact sensor to the nozzle portion 3a or the mold 7. - If it is a multi-song injection (YES in step 405), the central processing unit 11 converts the resin weight q into the resin weight qP for purging injection.
Step 406. ).

Step 407P) Adds the consumed resin weight QP for gas song injection stored in the memory 13 and this purging injection resin weight qP), and uses this addition result as a new total purging injection resin weight Q, memory 1 again as
Store in 3. On the other hand, if the whole mold is injected (Step 10)
5), the central processing unit 11 converts the resin weight q into the resin weight qD for in-mold injection.
D and this resin weight qD for in-mold injection are added (Stella: 7″407D), and this addition result is stored in the memory 13 again as a new overall consumed resin weight QD for in-mold injection.The central processing unit.

The total consumed resin weight Q for 79-song injection and the consumed resin weight QD for injection inside the mold are displayed on the display 14 (step 408). The central processing unit 11 repeats the operations from step 402 to step 408 until the molding operation of the injection molding machine stops (yEs in step 409), so that the injection molding process is performed as in the first-order formula. Resin weight qP
and the candy weight qD for injection into the mold.
The consumed resin weight Q for P-song injection and the consumed resin weight QD for injection into the song mold are determined.

QP=ΣqP ・・・・・・・・・・・・ (
5) QD=ΣqD・・・・・・・・・・・・
・ (6) QG The total weight of consumed resin for in-mold injection # is determined by the ratio a occupied by the cavity 7a in the mold 7, and is also calculated by the weight of the consumed resin for the total molded product QM and the weight of the consumed resin for the total waste material QS. It is divided into two clans. Here, the cavity ratio a is expressed by the following formula.

Therefore, the total consumed resin weight QM for molded products and the total consumed resin weight Qs for waste materials are expressed by a linear equation using the total consumed resin weight QD for injection into the mold and the cavity ratio a.

QM= aQn ・・・・・・・・・・・・
(8)Q3=(1-a)Qo -----・=・・−
--- (9) Referring to FIG. This is an example of sorting into categories. In this case, the screw outer diameter, resin specific gravity ρ, and cavity ratio a are input from the setting device 12, and
Consumption tree weight for certified purging injection 1 finger Q1. Both the total molded product consumed resin weight Q8 and the total waste resin consumed weight Q8 are initially set to O (step 501). Steps 502 to 507P and steps 502 to 506D are the same as steps 402 to 407° and steps 402 to 406D in FIG. 4, respectively.

The explanation will be omitted.

In step 506D, the central processing unit 11 converts the resin weight q into the total in-mold injection resin M amount qD, and then uses the quadratic equation to calculate the sprue runner resin weight (Is and molded product resin weight) consumed in one injection. Calculate qM (steps 506s and 506M).

qS=(1-a)qD・・・・・・・・・・・・
・αO=aqD ・・・・・・・・・・
...α(1) Next, the central processing unit 11 stores the memory 13
(Step 5078)
.

This addition result is stored in the memory 13 again as a new total waste resin consumption weight Q8. Similarly, the central processing unit 11
In step 5, add the total consumed resin weight QM for molded products and the resin weight qM for molded products stored in the memory 13.
07M), this addition result is stored in the memory 13 again as a new total molded product consumed resin weight QM. The central processing unit 11 displays the total E-song injection resin weight QP + the total molded product injection resin weight QM + and the total waste resin consumption Qs on the display 1.1 (step 508). The central processing unit 11 performs the operations of steps 501 to 508.

The molding operation of the injection molding machine stops (Y in step 509).
By repeating up to ES ), the purging injection resin weight qP is calculated as shown in equation (5) and the following equation.

Resin weight qS for sprue runner and resin weight qM for molded product
The total consumed resin weight QP for e-song injection, the total consumed resin weight Qs for waste materials, and the total consumed resin weight QM for molded products are obtained by integrating these.

QS=ΣqS ・・・・・・・・・・・・
(2) Qv=ΣqM・・・・・・・・・・・・
・αj Total resin consumption weight for molded products QM is further divided into two categories, depending on whether the product is good or not, the total consumed resin weight for molded products QG and the consumed resin weight for total defective molded products QN. be done. Methods for determining this defect include 1. For example, as described in Japanese Patent Application No. 175.794 filed earlier by the applicant of the present invention, the measurement time of the resin, the filling time, the amount of cushioning, the completion of holding pressure, etc. The screw position, maximum filling pressure, resin temperature, and mold temperature are extracted as quality control data for each injection degree.

By comparing these extracted quality control data with respective preset upper and lower limit values, it is possible to determine whether the product is good or defective.

Referring to FIG. 6, this embodiment is an example in which the total consumed resin weight for molded products QM is further divided into two general cases: the total consumed resin weight for molded products QG and the consumed resin weight for total defective molded products QN. It is. In this case, the screw outer diameter, resin specific gravity ρ, and cavity ratio a are input from the setting device 12, as well as the total consumed resin weight for purging injection QP, the total consumed resin weight for waste materials QCs, the total consumed resin weight for good molded products. QG and the consumed resin weight QN for total defective molded products are both initially set to O (step 601). Step 602 to Step 60
7P and steps 602~. Step 607. are the same as steps 502 to 507P and steps 502 to 5078 in FIG. 5, respectively, so their explanation will be omitted.

The central processing unit 11 continues to step 6078.

It is determined whether the product is good or not using the method described above (step 610). If it is determined to be good (NO in step 610)
), the central processing unit 11 combines the molded product resin weight QM with the good molded product resin weight qG (step 606, ), and the total molded product consumed resin weight Q6 stored in the memory 13.
Add this and the resin weight qG for a good molded product in step 6.
07o) This addition result is stored in the memory 13 again as a new total molded product consumption resin weight QG. On the other hand, if it is determined to be defective (YES in step 610), the central processing unit 11 sets the resin weight qM for molded products to the resin weight qN for defective molded products (step 606N), and the memory 13
Step 60: Add the total consumed resin weight QN for defective molded products stored in , and this resin weight qN for defective molded products.
7N), this addition result is stored in the memory 13 again as a new consumed resin weight QN for the total defective molded product. The central processing unit 11 calculates the total purging injection resin weight QP e h
The consumed resin weight for waste materials Q3-rb The consumed resin weight for good molded products QG and the consumed resin weight for total defective molded products QN are displayed on the display 14 (step 608). Central processing unit 1
1, the operations of steps 601 to 608 are stopped when the molding operation of the injection molding machine is stopped (YES in step 609).
) by repeating until

As shown in Equation (5), Equation 02, and the following equation, the weight of resin for purging injection qp a The weight of resin for sprue runner qB+
Resin weight qS for good molded products and resin weight q for defective molded products
The total consumed resin for purging injection 1 scene QP + the total consumed resin weight for waste material QSI, the total consumed resin weight for good molded products QG, and the consumed resin weight for recognized defective molded products QN are calculated by integrating N respectively.

Q, =Σqc ・・・・・・・・・・・・
04QN=ΣqN・・・・・・・・・・・・
・ α In the above-mentioned embodiment, the total consumed resin weight Q, total consumed resin weight for purging injection QP + consumed resin weight for injection in approved mold QD + consumed resin weight for total waste material QB + total consumed resin weight for molded product are displayed on the 1 display 14. Consumed resin weight QM + consumed resin weight for total molded products QG, and consumed resin weight for total defective molded products QN
Although this information is simply displayed, it is of course possible to transmit this information to a higher-level management converter.

〔Effect of the invention〕

As explained above, in the present invention, the screw position is detected and the consumed weight of the resin actually injected from the injection molding machine is calculated based on the screw movement view, so it is possible to accurately measure the consumed resin weight. There is an effect. In addition, conventionally, a dedicated measuring device was required to measure the weight of consumed resin, but in the present invention, the weight of consumed resin can be measured using only the equipment originally provided in the injection molding machine. There are advantages. Furthermore, there is an advantage that the weight of consumed resin can be measured separately into a plurality of ranges.

Remaining days below

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining the method for measuring the weight of consumed resin in an injection molding machine according to the first embodiment of the present invention, and FIG. 2 shows the configuration of the injection molding machine and the consumption for realizing the method shown in FIG. A sectional view and a block diagram showing a resin weight measuring device; FIG. 3 is a flowchart for explaining a method for measuring the weight of consumed resin in an injection molding machine according to a second embodiment of the present invention;
FIG. 4 is a flowchart illustrating a method for measuring the weight of consumed resin in an injection molding machine according to the third embodiment of the present invention, and FIG. 5 is a flowchart for measuring the weight of consumed resin in an injection molding machine according to the fourth embodiment of the present invention. Flowchart for explaining the method, No. 6
The figure is a flowchart for explaining a method for measuring the weight of consumed resin in an injection molding machine according to a fifth embodiment of the present invention. 9... Rotary encoder, 10... Interface, 11... Central processing unit, 12... Setting device, 13
...Memory, 14...Display unit. Figure 1 Figure 2 90-Tary encoder Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. By rotating a screw inserted into a plasticizing cylinder, the screw is moved back to measure the resin necessary for the molded product, and the resin is injected by moving the screw forward. A method for measuring the weight of resin consumed in an injection molding machine, which includes the steps of determining the amount of screw movement l in one injection from the screw position, and the step of determining the amount of screw movement l in one injection.
1 from the preset screw outer diameter D and resin specific gravity ρ.
A method for measuring the weight of consumed resin in an injection molding machine, which includes a step of calculating the weight q of resin consumed in one injection, and a step of calculating the total resin weight Q (=Σq) by integrating the resin weight q. 2. The injection molding machine according to claim 1, wherein the screw movement amount l is the screw retraction amount during measurement, which is the difference between the screw position l_E at the start of measurement and the screw position l_S at the end of measurement. How to measure the weight of consumed resin. 3. The injection molding machine according to claim 1, wherein the screw movement amount l is the screw advance amount during injection, which is the difference between the screw position l_S at the start of injection and the screw position l_E at the end of injection. How to measure the weight of consumed resin. 4. By rotating a screw inserted into a plasticizing cylinder, the screw is moved back to measure the resin necessary for the molded product, and by moving the screw forward, the resin is injected. A method for measuring the weight of resin, which includes the steps of determining the amount of screw movement l in one injection from the screw position;
an injection process that includes a step of calculating the total screw movement amount L (=Σl) by integrating the total screw movement amount L, and a step of calculating the total consumed resin weight Q from the total screw movement amount L, a preset screw outer diameter D, and resin specific gravity ρ. How to measure the weight of resin consumed by a molding machine. 5. By rotating a screw inserted into a plasticizing cylinder, the screw is retracted to measure the resin necessary for the molded product, and by advancing the screw, the resin is injected. The method includes a first step of determining the screw movement amount l in one injection from the screw position, and calculating the screw movement amount l, preset screw outer diameter D, and resin specific gravity ρ.
A second step is to determine the weight of resin q consumed in one injection, a third step is to classify which category the consumed resin weight q belongs to, and a step to integrate the resin weight for each category. and a fourth step of determining the weight of consumed resin for each category. 6. The third step includes a step of determining whether the resin weight q is an in-mold injection resin weight q_D injected into the mold or a purging injection resin weight q_P injected during purging injection. The fourth step includes a step of integrating the resin weight q_D for in-mold injection to obtain a total consumed resin weight Q_D (=Σ_q_D) for in-mold injection, and integrating the resin weight q_P for purging injection. The method for measuring the weight of consumed resin in an injection molding machine according to claim 5, comprising the step of determining the total weight of consumed resin for purging injection Q_P (=Σ_q_P). 7. The third step is a step of determining whether the resin weight q is an in-mold injection resin weight q_D injected into the mold or a purging injection resin weight q_P that is purged. , the weight of the resin for injection into the mold q_D is determined by the proportion a (<1
), the fourth step includes a step of dividing resin weight q_M for molded product and resin weight q_S for sprue runner from
A step of integrating the resin weight q_P for purging injection to obtain the total consumed resin weight Q_P (=Σ_q_P) for purging injection, and a step of integrating the resin weight q_M for molded product to obtain the total consumed resin weight for molded product Q_M (=Σ_q_M ), and calculating the consumed resin weight for total waste material Q_S (=Σ_q_S) by integrating the resin weight q_S for the sprue runner. Method. 8. The third step is a step of determining whether the resin weight q is an in-mold injection resin weight q_D injected into the mold or a purging injection resin weight q_P injected during purging. , the weight of the resin for injection into the mold q_D is determined by the proportion a (<1
), the process of dividing the resin weight q_M for the molded product and the resin weight q_S for the sprue runner, and the process of dividing the resin weight q_M for the molded product
The fourth step includes the step of determining whether the resin weight q_G for a good molded product is good as a product or the resin weight q_N for a defective molded product that is defective as a product, and the fourth step includes the step of determining whether the resin weight q_P for purging injection is a step of calculating the total consumed resin weight for purging injection Q_P (=Σ_q_p) by integrating;
A step of integrating the resin weight q_S for the sprue runner to obtain the total waste resin weight Q_S (=Σ_q_S), and a step of integrating the resin weight q_G for the good molded product to obtain the total consumed resin weight Q_G (=Σ_q_Q) for the good molded product. and a step of calculating the total consumed resin weight for defective molded products Q_N (=Σ_q_N) by integrating the resin weight q_N for defective molded products (=Σ_q_N). Resin weight measurement method.