JP3408631B2 - Injection compression molding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection compression molding machine for a compression compression molding machine for plastics and the like, in which mold clamping control is performed so that the wall thickness is uniform even in an asymmetrical molded product.

[0002]

2. Description of the Related Art In a conventional injection compression molding machine, when asymmetrically shaped parts are molded, the pressure distribution inside the mold becomes asymmetric during compression, resulting in unevenness and the fixed mold and the movable mold do not close in parallel. The thickness of the product was uneven and only an unsatisfactory molded product was obtained. For example, a cross-sectional view of a conventional injection compression molding machine on the mold clamping side is shown in FIG. 14. In this device, a pair of molds 7 and 8 are mounted between a fixed mold platen 1 and a movable mold platen 2. The resin 10 injected from the injection device into the molded product cavity 9 is compressed and molded. Mold clamping cylinders 4 are provided at four corners of the fixed mold board 1, and mold clamping force is transmitted from the mold clamping ram 5 inside to the mold boards 1 and 2 through the nut 6 and the tie rod 3. In addition, the mold clamping oil is 5
From the portion indicated by 0, it flows in the direction of arrows such as a, b, c, ... G, h, and flows into the mold clamping chambers 4a of the four mold clamping cylinders. At the time of molding, the resin 10 is injected into the molded product cavity 9 with the mold slightly opened as shown in the figure, and the resin 10 is compressed to fill the cavity 9 for molding. By slightly opening the mold at the time of injection in this way, the resin flow resistance in the mold is reduced by the amount of the opening, so that the mold clamping force can be reduced accordingly. Further, as described above, by applying compression after injection, the pressure inside the mold is made uniform, and a molded product with low distortion and no warp or sink can be expected. However, if the molded product is asymmetrical, the resin pressure distribution in the mold will also be asymmetrical, and this will cause the fixed and movable molds to not close in parallel during compression, resulting in a large variation in the molded product thickness. Occurs. That is, originally, as shown in (a) → (b) of FIG. 15, the fixed / movable molds should be compressed while maintaining the parallel state. However, as shown in (a) → (c), There has been a problem that the thickness of the molded product becomes uneven due to collapse.

[0003]

As described above, in the prior art, when injection-compressing an asymmetric molded product, the resin pressure distribution in the mold becomes asymmetric, so that the fixed and movable molds are parallel to each other. There was a drawback that the thickness of the molded product was not uniform and the thickness of the molded product was not uniform. Therefore, the present invention appropriately controls the pressures or flow rates of four mold clamping cylinders in a mold clamping device having mold clamping cylinders at four corners when an asymmetric molded product is injection-compressed and molded. An object of the present invention is to provide an injection compression molding machine that can make the wall thickness uniform and solve the above-mentioned conventional problems.

[0004]

Therefore, according to the present invention, in a mold clamping apparatus having mold clamping cylinders at four corners, an electric pressure adjusting valve is provided in each of the mold clamping side hydraulic passages of the four mold clamping cylinders. , The pressure control valve controls the mold clamping pressure in the compression process in one or more stages in time for each mold clamping cylinder, and automatically according to the wall thickness deviation at the four corners of the actual molded product. For correcting and changing the set value of the pressure regulating valve,
Also, the set values of the pressure control valve according to the wall thickness deviations at the four corners of the molded product were calculated by a correction formula with the wall thickness deviation as a variable at the beginning, and after the data of a certain number of conditions was collected, The optimum condition is calculated and set by using the multiple regression analysis. Furthermore, an electric flow rate control valve is provided in each of the four mold clamping cylinder hydraulic pressure flow passages. The mold clamping oil flow rate in the compression process is controlled by one step or a plurality of steps in time for each mold clamping cylinder, and the flow rate adjusting valve is automatically adjusted according to the wall thickness deviation at the four corners of the actual molded product. The set value of is modified and changed, and this is used as a means for solving the problem. In addition, the set values of the flow rate control valve according to the wall thickness deviations at the four corners of the molded product were calculated by a correction formula with the wall thickness deviation as a variable at the beginning, and after the data of a certain number of conditions was collected, Optimal conditions are calculated and set using multiple regression analysis, and an electric flow rate control valve and an electric pressure control valve are further provided in each of the four mold clamping cylinder hydraulic passages. The mold clamping oil flow rate is controlled by the flow rate adjusting valve in the first compression step for each mold clamping cylinder, and the mold clamping pressure is controlled by the pressure adjusting valve in the next second compression step. The set values of the pressure adjusting valve are automatically corrected and changed according to the thickness deviations at the four corners of the product, and the flow rate adjusting valve and the pressure adjusting valve of the molded product are adjusted according to the thickness deviations at the four corners. Initially, the set value is calculated by a correction formula with the thickness deviation as a variable, and Since when the number of data can be collected as it becomes as calculates and sets the usage and optimum multiple regression analysis, it is an unit for which a problem solution.

[0005]

[Operation] In the mold clamping device having the mold clamping cylinders at the four corners,
An electric pressure adjusting valve is provided in the hydraulic passages on the mold clamping side of each of the four mold clamping cylinders, and the mold clamping pressure in the compression process is set to one stage or multiple stages in time for each mold clamping cylinder by the pressure regulating valve. Control. At this time, the wall thickness deviation of the molded product is calculated for each molding shot by automatically calculating and changing the set value of the pressure adjusting valve according to the wall thickness deviation of the four corners of the actual molded product. The mold clamping pressure is controlled so that
Finally, the thickness of the molded product can be made uniform. Further, the set value of the pressure control valve is calculated by a correction formula in which the thickness deviation is used as a variable in the beginning, and after the data of a certain number of conditions can be collected, the optimum condition is determined using multiple regression analysis. By calculating and setting, the thickness deviation of the molded product can be corrected automatically and quickly, and an injection compression molded product with a uniform molded product thickness can be easily obtained in a few tens of shots.

Further, for the injection compression molded product which is more suitable for the flow rate control than the pressure control, an electric flow rate adjusting valve is similarly provided in each of the mold clamping side hydraulic flow passages of the four mold clamping cylinders. With the same flow rate adjusting valve, the mold clamping flow rate in the compression step is temporally controlled in one stage or a plurality of stages for each mold clamping cylinder.
At this time, the wall thickness deviation of the molded product is calculated for each molding shot by automatically correcting and changing the set value of the flow rate adjusting valve at the four corners of the actual molded product according to the wall thickness deviation. It is possible to control the mold clamping oil flow rate so as to correct it with the shot of, and finally to make the thickness of the molded product uniform. Furthermore, at first, the set value of the flow rate control valve is calculated by a correction formula with the thickness deviation as a variable, and after the data of a certain number of conditions can be collected, the multiple regression analysis is used to calculate the optimum condition. By setting the above, the thickness deviation of the molded product can be corrected automatically and quickly, and an injection compression molded product with a uniform molded product thickness can be easily obtained in a few tens of shots.

Further, in order to correspond to the injection compression molded product suitable for either the pressure control or the flow rate control, an electric flow rate adjusting valve and an electric pressure control valve are provided in the hydraulic flow passages on the mold clamping side of each of the four mold clamping cylinders. It is also possible to provide an adjusting valve, control the mold clamping oil flow rate by the flow rate adjusting valve in the first compression step for each mold clamping cylinder, and control the mold clamping pressure by the pressure adjusting panel in the next second compression step. . At this time, by automatically calculating and changing the set values of the flow rate adjusting valve and the pressure adjusting valve according to the thickness deviations at the four corners of the actual molded product,
For any molded product, the flow rate and pressure of the mold clamping oil can be controlled so as to correct the wall thickness deviation of the molded product in each subsequent shot, and finally the molded product wall thickness can be made uniform. Further, the set values of the flow rate control valve and the pressure control valve are calculated by a correction formula with the thickness deviation as a variable at the beginning, and after the data of a certain number of conditions can be collected, the multiple regression analysis is used. By calculating and setting the optimum conditions, the thickness deviation of the molded product can be corrected automatically and quickly, and an injection compression molded product with a uniform molded product thickness can be easily obtained in a few tens of shots. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments of the drawings. FIGS. 1 to 13 show the embodiments of the present invention. First of all,
The first embodiment of FIG. 6 will be described. FIG. 1 is a sectional view of the injection compression molding machine of this embodiment on the mold clamping side. FIG. 2 is a sectional view taken along line AA of FIG. Shown in. In FIG. 1, 1 is a fixed platen, 2 is a movable platen, 3 is a tie rod, 4 is a mold clamping cylinder, 5 is a mold clamping ram, 6 is a nut, 7 is a fixed mold,
8 is a movable mold, 9 is a cavity, and 10 is a resin, which are the same as those in the conventional example. By the way, when molding a molded product having a non-uniform shape as shown in FIG.
In the conventional apparatus, the pressure distribution of the resin 10 in the cavity 9 of FIG. 1 becomes asymmetrical, and even pressure exerted on the four mold clamping cylinders will cause the mold to be twisted and closed, resulting in the thickness of the molded product. Becomes uneven. Therefore, in this embodiment, the mold clamping chambers 4a of the four mold clamping cylinders 4 are arranged as shown in FIG.
An electric pressure adjusting valve 11 is connected to each of the cylinders, and the pressure of each mold clamping cylinder is controlled to be constant by this pressure adjusting valve 11. Therefore, as shown in FIG. 4 or 5, the mold clamping pressure of each mold clamping cylinder can be set to one stage or two or more stages for compression. Then, as shown in the pressure control flow chart of FIG. 6, the mold clamping pressure can be changed and compressed. Then, the mold clamping pressure is changed as shown in the pressure control flow chart of FIG.

The change of the setting of the mold clamping pressure will be explained below. In the first one shot, the uniform mold clamping pressure is set in each of the four cylinders, and then the wall thicknesses at the four corners of the actual molded product (see FIG. 3). H _{P1 to} H _P4 ) are measured and the mold clamping pressure is corrected by the following correction formula. However, the symbols are determined as follows. H _Pi : Thickness of four corners of the molded product (i = 1 to 4) H ₀ : Average thickness of molded product (average of the four corners thickness) P ₀ : Uniform set pressure of each cylinder for a given mold clamping force P _Ci : Set pressure of each cylinder (i = 1 to 4) The subscript corresponds to the cylinder closest to each of the four corners of the molded product 1) Up to the nth time (the number of data is insufficient for multiple regression analysis) If)

[Equation 1] Where α is a relaxation coefficient (about 0.5 to 1)

2) From the (n + 1) th time (when the number of data capable of multiple regression is accumulated) Using multiple regression analysis, the multiple regression equation of each mold clamping pressure with respect to the molded product wall thickness at the four corners is given by the following equation. It is represented by a function f _i such as

## EQU2 ## H _Pi = f _i (P _C1, P _C2 , P _C3 , P _C4 ) where i = 1 to 4 Next, using this multiple regression equation, the wall thickness deviations (H _Pi −H
₀ ) is minimized, and the optimum P _Ci is calculated. The number of times n is determined by the number of data required for multiple regression analysis, and as described above, when the compression is a single stage clamping pressure,
It is about n = 5. When the number of stages of compression is two or more, the respective mold clamping pressures are increased by the number of stages, and the compression can be similarly corrected. However, since the number of data required for multiple regression increases, the number of times n also increases.

Next, the second embodiment will be described with reference to FIGS. 7 to 10. FIG. 7 is a sectional view of the injection compression molding machine of this embodiment on the mold clamping side. The cross-sectional view of B-B in FIG.
These are the same as FIGS. 2 and 3, respectively. The present embodiment is characterized in that an electric flow rate adjusting valve 12 of FIG. 7 is provided in place of the electric pressure adjusting valve 11 of FIG. 1, and the other structures are the same as those of the first embodiment. As shown in FIG. 7, in the mold clamping chambers 4a of the four mold clamping cylinders 4, the electric flow rate adjusting valves 12 are respectively provided.
Are connected, and the flow rate of the pressure oil to each mold clamping cylinder is controlled to be constant by the flow rate adjusting valve 12, so that the mold clamping oil flow rate of each mold clamping cylinder is as shown in FIG. 8 or FIG. It can be compressed by setting it in one stage or two or more stages. Then, as shown in the flow rate control flow chart of FIG. 10, the mold clamping oil flow rate is changed.

The change in the setting of the mold clamping oil flow rate will be described below. In the first shot, the uniform mold clamping oil flow rate is set for each of the four cylinders, and then the wall thicknesses at the four corners of the actual molded product (see FIG. 3 HP _{P1 to} HP ₄ ) are measured and the mold clamping oil flow rate is corrected by the following correction formula. However, the symbols are determined as follows.
Note that H _Pi and H ₀ are the wall thicknesses at the four corners of the molded product and the average wall thickness, as in the first embodiment. Q ₀ : Equal set flow rate of each cylinder corresponding to a predetermined mold clamping speed Q _Ci : Set flow rate of each cylinder (i = 1 to 4) The subscript corresponds to the cylinder closest to each of the four corners of the molded product 1 ) Up to the nth time (when the number of data is insufficient for multiple regression analysis)

[Equation 3] However, β: relaxation coefficient (about 0.5 to 1)

2) From the (n + 1) th time (when the number of data capable of multiple regression is accumulated) Using multiple regression analysis, the multiple regression equation of each mold clamping oil flow rate with respect to the molded product wall thickness at the four corners is calculated as follows. It is represented by a function g _i like an expression.

Equation 4] _{H Pi = g i (Q C1} , Q C2, Q C3, Q C4) where, i = 1 to 4 and then by using this regression equation, the four corners of the wall thickness deviation (H _Pi -H
₀ ) is minimized, and the optimum Q _Ci is calculated. The number of times n is the same as in the first embodiment, and is determined by the number of data required for multiple regression analysis. When the compression is performed in two stages or more, the flow rates of the mold clamping oils can be corrected in the same manner only by increasing the mold clamping oil flow rates by the number of stages. However, since the number of data required for multiple regression increases, the number of times n also increases.

Next, the third embodiment will be described with reference to FIGS. 11 to 13. FIG. 11 is a sectional view of the injection compression molding machine of the present embodiment on the mold clamping side. 2 and 3, respectively. The present embodiment is characterized in that an electric flow rate adjusting valve 12 of FIG. 7 is provided in the flow path in addition to the electric pressure adjusting valve 11 of FIG. 1, and the other structure is the same as that of the first embodiment. Is. As shown in FIG. 11, an electric pressure adjusting valve 11 and an electric flow rate adjusting valve 12 are connected to the mold clamping chambers 4a of the four mold clamping cylinders 4, respectively. The mold clamping oil pressure and flow rate are controlled to be constant. Therefore, in this embodiment, the pressure and the flow rate of each mold clamping cylinder can be set in two stages or more as shown in FIG. That is, to explain with the two-stage compression in FIG. 12, since the compression stroke becomes large in the first-stage compression (first compression process), the flow rate of each mold clamping cylinder is controlled,
In the second stage (second stage compression step), the mold is not displaced so much and resin compression due to the mold internal pressure occurs, so the mold clamping pressure is controlled. Then, as shown in the flow rate / pressure control flow chart of FIG. 13, the setting of the flow rate and pressure of the mold clamping oil is changed.

The change of the setting of the mold clamping oil flow rate and pressure will be described below. In the first one shot, the uniform mold clamping oil flow rate and pressure are set in each of the four cylinders, and then 4 of the molded product of the embodiment is set. Measure the wall thickness of the corner (H _{P1 to} H _{P4 in} FIG. 3) and correct the mold clamping oil flow rate by the following correction formula. However, the symbols are determined as follows. Note that H _Pi and H ₀ are the wall thicknesses and average wall thicknesses at the four corners of the molded product, as in the first embodiment, and P ₀ and Q ₀ are the same for each mold clamping cylinder as in the first and second embodiments. Set pressure and set flow. Q _kCi : Set flow rate of each cylinder in kth stage compression P _kCi : Set pressure of each cylinder in kth stage compression where k = 1 to 2, i = 1 to 4 The cylinder closest to each of the four corners of the molded product corresponds 1) Up to the nth time (when the number of data is insufficient for multiple regression analysis)

[Equation 5]

[Equation 6] However, α, β: relaxation coefficient (about 0.5 to 1)

2) From (n + 1) th time (when the number of data capable of multiple regression is accumulated) Using multiple regression analysis, multiple regression formulas of each mold clamping oil flow rate / pressure with respect to the molded product thickness at the four corners _Is represented by a function h _i as follows.

[ _Formula 7] HPi = h _i (Q _1C1, Q _1C2, Q _1C3, Q _1C4, P
_2C1, P _2C2, P _2C3, P _2C4 ) where i = 1 to 4 Next, using this multiple regression equation, the wall thickness deviations at the four corners (H _Pi −H
₀ ) is minimized and the optimum Q _1Ci and P
_{Calculate 2Ci} . In addition, Q 2 _Ci and P which are not in the above formula
_{Set 1Ci} to a sufficiently large value (actually, it is not related to control). The number of times n is determined by the number of data required for multiple regression analysis, and when the compression has two stages of mold clamping oil flow rate / pressure as described above, n = 9.

[0017]

As described in detail above, according to the present invention, either or both of the electric pressure adjusting valve and the electric flow adjusting valve are installed in the hydraulic circuit of each of the four mold clamping cylinders. By molding while correcting the mold clamping pressure or mold clamping oil flow rate of each cylinder during injection compression due to the thickness deviation of the four corners of the molded product, it is possible to easily obtain a molded product with a uniform molded product thickness. it can. As a result, it is possible to solve the problem of uneven wall thickness that has occurred in the past with asymmetrical injection-molded products.
Further, the range of molded products to which injection compression can be applied is greatly expanded.

[Brief description of drawings]

FIG. 1 is an injection compression molding machine showing a first embodiment of the present invention.
It is a partial cross section side view.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a shape diagram of the molded product of FIG.

FIG. 4 is a change diagram of a mold clamping pressure at a first stage of compression when molding is performed by the molding machine of FIG. 1.

5 is a change diagram of the mold clamping pressure at two stages of compression when molding is performed by the molding machine of FIG.

6 is a control flow chart of a mold clamping pressure by the molding machine of FIG.

FIG. 7 is an injection compression molding machine 1 showing a second embodiment of the present invention.
It is a partial cross section side view.

8 is a change diagram of the mold clamping oil flow rate of the first stage of compression when molding is performed by the molding machine of FIG.

9 is a change diagram of a mold clamping oil flow rate of two stages of compression when molding is performed by the molding machine of FIG. 7.

10 is a control flow chart of a mold clamping oil flow rate by the molding machine of FIG.

FIG. 11 is a partial sectional side view of an injection compression molding machine showing a third embodiment of the present invention.

FIG. 12 is a change diagram of a mold clamping oil flow rate / pressure at two stages of compression when molding is performed by the molding machine of FIG. 11.

13 is a control flow chart of mold clamping oil flow rate / pressure by the molding machine of FIG. 11. FIG.

FIG. 14 is a partial sectional side view of a conventional injection compression molding machine.

FIG. 15 is an explanatory diagram of a mold operation in injection compression.

[Explanation of symbols]

1 Fixed Mold Board 2 Movable Mold Board 3 Tie Rod 4 Mold Clamping Cylinder 4a Mold Clamping Cylinder 4a Mold Clamping Chamber 5 Mold Clamping Ram 6 Nut 7 Fixed Mold 8 Movable Mold 9 Cavity 10 Resin 11 Electric Pressure Regulator 12 Electric Flow Regulator 20 four corners of the wall thickness of the molded article _{H P1, H P2, H P3} , H P4 moldings

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-269751 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (6)

(57) [Claims] 1. A mold clamping device having mold clamping cylinders at four corners, wherein each of the four mold clamping cylinders is provided with an electric pressure regulating valve in a hydraulic passage on the mold clamping side, and the mold is used in a compression process by the pressure regulating valves. The clamping pressure is controlled in one step or multiple steps in time for each mold clamping cylinder, and the set value of the pressure control valve is automatically modified and changed according to the wall thickness deviation at the four corners of the actual molded product. An injection compression molding machine characterized by: 2. The injection compression molding machine according to claim 1, wherein the set values of the pressure control valve according to the wall thickness deviations at the four corners of the molded product are initially set by a correction equation using the wall thickness deviation as a variable. An injection compression molding machine characterized by calculating and setting optimum conditions using multiple regression analysis after the calculation and collection of data for a certain number of conditions. 3. A mold clamping device having mold clamping cylinders at four corners, wherein an electric flow rate adjusting valve is provided in each of the mold clamping side hydraulic flow paths of the four mold clamping cylinders, and the mold for compression process is provided by the flow rate adjusting valves. The clamping oil flow rate is controlled in one step or multiple steps in time for each mold clamping cylinder, and the set value of the flow rate adjustment valve is automatically corrected according to the thickness deviation of the four corners of the actual molded product. An injection compression molding machine characterized by being changed. 4. The injection compression molding machine according to claim 3, wherein the set values of the flow rate adjusting valve according to the wall thickness deviations at the four corners of the molded product are initially set by a correction equation using the wall thickness deviation as a variable. An injection compression molding machine characterized by calculating and setting optimum conditions using multiple regression analysis after the calculation and collection of data for a certain number of conditions. 5. A mold clamping device having mold clamping cylinders at four corners, wherein each of the four mold clamping cylinders is provided with an electric flow rate adjusting valve and an electric pressure adjusting valve in a hydraulic flow path on a mold clamping side, and each mold clamping cylinder is provided. For each cylinder, the mold clamping oil flow rate is controlled by the flow rate adjusting valve during the first compression step, and the mold clamping pressure is controlled by the pressure adjusting valve during the next second compression step.
An injection compression molding machine, characterized in that the set values of the flow rate adjusting valve and the pressure adjusting valve are automatically modified and changed according to the wall thickness deviation of a corner. 6. The injection compression molding machine according to claim 5, wherein the set values of the flow rate control valve and the pressure control valve according to the wall thickness deviations at the four corners of the molded product are set as variables at the beginning. The injection compression molding machine is characterized in that the optimum condition is calculated and set by using the multiple regression analysis after the data of a certain number of conditions can be collected by the correction formula.