JPH04201429A - Controlling apparatus for injection molding - Google Patents

Abstract

PURPOSE:To make it possible to keep stable quality of a molded item even when changes in environmental conditions occur by calculating successively amt. of correction of set values for stabilizing the quality to changes in the environmental conditions from set values of molding condition and detected values of temp. and pressure when a good product is molded. CONSTITUTION:Set values on injection speed and dwelling are input in a main control apparatus console and a test molding is performed to determine an optimum set value, which is transferred to a resin condition-control apparatus. The resin condition-control apparatus calculates a time pattern k0(t) from k=v/R =T/p wherein v is specific vol.; R is a const. determined by the resin; pressure p is a measured time pattern; T is resin temp. On every molding, the time pattern k(t) is calculated and deviation areas from K0(t) at the proceeding molding S1, S2 and S3 are obtd. and slide time t1, t2 and t3 are calculated by a specified calculation equation and points of time A1, A2 and A3 on a time- dwelling pressure curve is shifted by the above described time to determine amt. of correction of set values of pressure. The main control apparatus controls injection speed and resin pressure based on this amt. of correction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for an injection molding machine, and particularly to an improvement in pvT control.

(Prior art) In order to stably produce precision molded products for a long time using an injection molding machine, the following things are important. The temperature of the mold gradually increases due to heat transfer from the resin to the mold during molding. Furthermore 1. From the mold to the molding machine body.

Heat is transferred to the atmosphere, and it takes several hours for the whole to reach a -like temperature. Also, if you observe the temperature and moisture content of the resin supplied from the hot tub over a long period of time, you will notice that it changes gradually. These effects appear on the quality of the molded product, for example, as changes in weight.

FIG. 8 shows measurement data of the mold temperature θ, which is one of the above environmental conditions. In order for such environmental conditions to become constant, molding must be carried out continuously for several hours.

Figure 9 shows the results of producing molded products under varying environmental conditions and measuring the weight of one molded product. When the environmental conditions fluctuate as in this example, no matter how accurately individual molding conditions such as injection speed and pressure are controlled, it is not possible to maintain a stable quality.

Therefore, when performing precision molding, it is necessary to modify the injection speed and pressure settings in accordance with changes in environmental conditions.

Therefore, a control method based on a first-order concept has been proposed under the name of pvT control. (For example, Japanese Patent Application No. 1-284
No. 614 and Japanese Patent Application No. 2-4446). FIGS. 10 and 11 are simplified schematic diagrams for explaining the molding function in an easy-to-understand manner.

In FIG. 10, a screw 101 is disposed inside a heating cylinder 100 so as to be able to rotate and reciprocate, and this screw 101 is driven to reciprocate by an injection cylinder 102 and rotationally driven by a one-rotation drive system 103. . By rotating and reciprocating the screw 101, the resin in the heating cylinder 100 is filled into the cavity 105 of the mold 104 and press-molded.

As shown in FIG. 11(a), the mold is a mold for a molded product, and if the cavity 105 is filled with a resin of a fixed weight for each molded product, molded products with little variation in weight should always be obtained. be.

However, the resin was heated to a high temperature using a heating cylinder.

The resin is melted, filled into a cavity using an injection cylinder, and cooled to near room temperature when taken out as a molded product, so the specific volume (reciprocal of density) of the resin when filled is
The difference ΔV between + and the specific volume v2 when taken out as a molded product is very large.

That is, if the resin is simply poured into a mold, the molded product left in the air will shrink significantly as shown by the broken line on the right side of FIG. 11(a).

This means that the weight of the molded product taken out is less than the desired weight, and the molded product is also smaller in two dimensions.

Therefore, 1. In the normal molding process, resin filling (injection process)
After that, as shown in FIG. 11(b), pressure is applied to the resin using the injection cylinder 102 (pressure holding step), and the difference in specific volume ΔV is
The resin is filled with an amount of extra resin corresponding to .

However, if the environmental conditions change, the resin temperature T at the end of the injection process will change slightly, and the weight will gradually change.

Therefore, when the resin temperature T is high or the mold temperature is high, the specific volume V is large, so the pressure in the pressure holding step is increased and an extra amount of resin is filled. Conversely, when the resin temperature T or the mold temperature is low, the pressure is lowered and less resin is filled. In this way, while measuring the resin temperature T or mold temperature, the set value of pressure p is corrected, and the difference in specific volume ΔV
The general term for methods for making the value as small as possible is pvT control, which takes the symbols of these variables.

To specifically determine the set value of pressure p, use the resin's state equation (Spencer's equation).

(p+ω)(v-π)=R(T+273) (1)
Use. Here, ω, π, and R are constants determined depending on the type of resin. The set value of the pressure p is not a constant value, but must be given as a time function p,(t) in response to temperature changes. The way to give pr (t) in pvT control is as follows.

First, if we draw a constant p'' straight line on a plane with vT as a variable according to equation (1), it will look like the thin line in Figure 12 (p+
~ps). If we draw the trajectory of the resin during the molding process, it will look like the thick line in Figure 12 (A-B→C-D-
E). I indicates the injection process, and 1 is used to fill the mold cavity at high speed with resin heated to TA in the plasticization process.
The temperature does not drop much, but the pressure rises rapidly from pl to p4. pas, m p 4 is the allowable pressure to not destroy the mold, 1 point, B is pl, after reaching 8 is the pressure holding process■
The pressure is maintained up to point C. During this time, the resin is cooled in the mold and its temperature drops to T.

Point C is the intersection of target specific volume v1 and p□8.

The pressure is lowered along the straight line ■ vssv. Point C'
The gate of the mold is closed to complete the pressure holding process, and in the cooling process the molded product is cooled to a point C' near room temperature, and the molded product is taken out. At this point, the temperature is TD, and after further cooling in the air, the temperature is T.
When it comes to E, the specific volume becomes v2. Since it is used as a molded product in the state of specific volume v2, + vl '2
If −ΔV is small and there are few variations, the molded product will be highly accurate. Therefore, 1 normal pressure p1. ! Make it as high as possible.

Alternatively, the set value is selected so as to move the point C as low as possible and to reduce the difference ΔV in specific volume.

The locus in FIG. 12 is drawn for three variables: p+v+T. Since only one variable is defined in each of the steps (1) and (2), it is necessary to define one more variable among the remaining two variables in order to actually draw the trajectory.

The last variable is determined by equation (1). Therefore,
The approximate formula (time pattern) for the time function of the resin temperature is calculated as follows from the set values and measured values that change for each molded product.

Tv (t) = Tw + (8/yr2) *
(TMO-TV)*exp (-a@fl π2
t/52) where TM gives an approximate value of the resin temperature,
TW is the measured value of mold temperature. TMO is the measured value of the resin temperature at the start of holding pressure (point B in FIG. 12), S is the average wall thickness of the molded product, and a@, , is the equivalent thermal conductivity.

(Equation 2) includes the measured value of the mold temperature or resin temperature, so even if the environmental conditions change, the set value can be corrected to minimize the change in the specific volume difference ΔV. The conventional idea of pvT control is that when the environmental conditions change and the mold temperature rises, the overall time pattern of resin temperature changes from equation (2) as shown in Figure 13. (indicated by the dashed line in the figure).Next.

From equation (1), v−v,, pmp□1 (point C in Fig. 12
) is determined, and the time to reach this temperature Tc is also shifted to the right as shown in FIG. 13 (tc→t,').

Thereafter, the specific volume is kept constant at y m y . At this time, by substituting equation (2) into equation (1), the pressure setting value p is corrected to the time pattern shown by the broken line in FIG. When the temperature of the mold decreases, this is the opposite, resulting in the time pattern shown by the dashed-dot line in FIGS. 13 and 14.

(Problem to be solved by the invention) The above is an outline of conventional pvT control, and if the trajectory shown in Figure 12 is always achieved even if the environmental conditions change, the state change of the resin will be constant. The idea is that the quality of the molded product will also be stable. However, the actual molded product is shown in Figures 11(a) and (b).
Especially when it comes to precision molded products, rather than simple shapes as shown in the figure.

Its shape becomes complex. For example, it is normal for there to be a temperature distribution in the resin being filled, as shown in FIG. 11(C). In this example, the shaded area represents the resin in the high temperature range where the temperature drop is small, and the cross lined area represents the resin in the low temperature range where the temperature drop is large. When this is molded under a pressure similar to -, as shown by the broken line on the right side of Figure 1, the amount of shrinkage is different, resulting in stress distribution.
This results in a distorted molded product.

When the locus on the pvT diagram of the resin in FIG. 15, which shows an example of an actual molded product, is experimentally determined, it becomes as shown in FIG. 16. Subscript a in FIG.

b and c indicate the measurement positions at each part a, b, and c of the molded product in FIG. 15. Inside the molten resin beam server 106, the temperature TA and pressure p1 are uniform at first, but when the cavity is filled, the temperature drops and a pressure distribution occurs, such as Ba 1 Bb + B. When it spreads and starts holding pressure, it is C,,C,.

/co, the pressure distribution decreases somewhat, but the temperature distribution remains. Therefore, if you modify the pressure setting while keeping the entire area uniform as in the past, there may be an increase in the amount of resin in some areas.
On the other hand, if the amount decreases, the stress distribution becomes large, and the state of the resin in precision molded products cannot be precisely controlled. Therefore, in the case of precision molding, when the environmental conditions change, the difference in specific volume Δ
v,,Δv5. It is necessary to reduce the difference between ΔV. In addition, as the trajectories become more widely dispersed in a more plurality of molded products, it is becoming important to develop correction methods to reduce these differences.

In view of the above-mentioned problems, the present invention is designed to reduce the influence of environmental conditions such as mold temperature and resin temperature during molding by expressing in advance the influence of these fluctuations on molded product quality as a function. It is an object of the present invention to provide a control device for an injection molding machine that corrects a pressure setting value during molding so as to maintain stable molded product quality even if there are fluctuations.

(Means for Solving the Problems) A control device for an injection molding machine according to the present invention includes a mold temperature detector, a resin temperature detector, and a resin pressure detector as resin condition detection means, and includes injection speed, holding pressure, After molding is performed to obtain a good molded product based on the molding conditions set by the manual means and the means for inputting molding conditions such as resin pressure, detection signals from each of the detectors are sent.・Calculate the time function curve based on a predetermined calculation formula using

After that, the resin condition control device calculates a time function curve each time molding is performed, and calculates the amount of pressure setting value correction in the pressure holding process by determining the deviation area between the time function curve and the time function curve calculated in the immediately preceding molding cycle. and a main controller that controls the injection speed, resin pressure, etc. using the molding conditions and the pressure setting value correction amount.

(Example) First, the principle of the present invention will be explained.

First, consider pressure and temperature changes when molding a plate-shaped molded product as shown in FIG. 15. If the wall is thick, the resin may be cooled to some extent at the gate near the mold entrance, creating a temperature gradient in the thickness direction, or the high-temperature resin may pass through the center and move forward without being cooled much at all.

It is filled forward (towards the right in the figure). When filling is completed, the temperature is uniform or slightly higher at the tip (point C). The pressure is also uniform throughout. However, as the wall thickness decreases, the cooling at the wall surface becomes rapid, the resin being filled is also cooled, and the resin sent forward becomes cooled. Furthermore, the viscosity of the resin increases due to a decrease in temperature, and the resistance of the flow path increases, resulting in an increase in pressure gradient.

This tendency becomes even more severe in precision molded products having complex structures such as branching, and the distribution of the trajectories shown in FIG. 16 mentioned above also becomes large.

Therefore, the injection speed and pressure setting values for precision molded products are not simple, but are determined by the operator through trial and error based on experience and intuition for each molded product.

For example, for the molded product shown in FIG. 15, which has a thin wall thickness and a large temperature gradient and pressure distribution, the time pattern of the injection rate and the pressure p as shown in FIGS. 2 and 3 are set values.

In Figure 2, the injection speed is initially P. The high speed is set in the P1 section to prevent the resin from rapidly cooling and solidifying near the gate. In the P and P2P3 sections, the injection speed is lowered to prevent resin flow disturbances such as jetting. The period between P and P4 is a filling section in which the speed is gradually increased in order to uniformly fill all parts with the resin to be cooled. This is because the resin flow rate gradually decreases at the tip as it cools. The upper part of FIG. 2 shows a traveling wave at the tip of the resin flow when the resin is filled regularly. However, if the speed is increased too much to the end, the flow collides with the wall at the tip, causing a sudden pressure rise, which in turn creates a large stress distribution inside the molded product, so as filling approaches completion, P4P occurs.

Reduce speed in between. At the right end of the upper part of FIG. 2, the arrow that turns back inside the molded product indicates the reversal of the flow due to collision.

Next, when filling is completed, the flow suddenly stops and the pressure increases overall, or at this time, the pressure decreases from the tip of the flow toward the gate, contrary to when filling. This pressure collides with the pressure holding the resin from the gate side in the middle and spreads throughout.

The point at which such a transient state ends is the point at which the actual pressure holding starts, and thereafter no large flow of resin occurs, so that fluctuations in pressure distribution also become small. The resin temperature gradually cools down naturally through heat transfer on the mold cavity wall. As mentioned above, as the wall thickness of the molded product becomes thinner or the shape becomes more complex, the pressure and temperature distribution of the resin during filling will change in a complicated manner, determining the initial state of the pressure holding process, and affecting the molded product later on. Affects stress distribution.

When entering the pressure holding process, starting from the initial state determined in the filling process, a pressure cover turn is set in which the stress distribution is reduced as shown in FIG. 16 described above.

In the above example, where the temperature distribution gradually decreases from the gate side toward the back (right side of the figure) and tends to increase by 1 stress distribution, the setting pattern is as shown in FIG. 3. First Q. In the Q1 section, the temperature at the tip suddenly drops, so the pressure is increased to compress it to a predetermined specific volume ■ as quickly as possible. however.

The pressure is set to a value lower than p0.8 which does not break the mold.

During this time, the resin temperature near the middle of the molded product (point b in Figure 15) also decreases, and the pressure distribution becomes uniform throughout.
Gradually, as shown in FIG. 12, settings close to the pressure cover turn calculated from the concentrated locus are made between Q and 02. The last part Q203 is set for the area near the gate, but the cooling rate of the 1st gate part is faster than the others, so if you set the pressure cover turn too faithfully to the basic pattern, it will half solidify at the 2nd high pressure. This compresses the resin, destroying the gate part and leaving scratch-like marks on the surface. Therefore, Q2Q
In the 3rd section, the pressure setting value is lower than the basic pattern shown in FIG.

These series of injection speed and pressure cover turn settings are unique to each resin and molded product, and are performed solely by the operator's experience and intuition while visually inspecting the quality of the molded product each time the settings are changed. However, since the final product is a highly accurate precision molded product, it turns out that the pattern searched by the operator implicitly includes the flow characteristics and pvt characteristics of the resin of the precision molded product. Become.

Based on this viewpoint, the present invention estimates the flow characteristics from the set pattern, determines a functional relationship, and uses this function to correct the pattern in response to changes in environmental conditions. This makes it possible to realize a pvT control method that accurately controls the state of the resin for complex molded products without having to prepare unique parameters such as resin characteristics and the shape of the mold cavity.

The control method and its implementation method will be explained below using examples.

FIG. 1 shows an injection molding machine and its control system according to the present invention.
Only the parts necessary for explaining the embodiment are shown. The injection molding machine is the same as that shown in FIG. 10, but a resin pressure detector 110 in the entire mold is used as a resin state detection means. Mold temperature detector 111. All in-mold resin temperature detectors 112 are installed in each mold 104, and a resin temperature detector 113 is installed in the heating cylinder 100. Regarding the control system, resin condition control device 11. Only a main controller 12 for controlling resin injection speed and pressure and a mold temperature controller 13 are shown.

The resin condition control device 11 includes a resin pressure detector 110 in all molds.
, the temperature detection signal Sθ from the mold temperature detector 111, the temperature detection signal ST from the resin temperature detector 112 in the mold, the temperature detection signal STM from the resin temperature detector 113, and the main The molding condition signal from the control device 12 is input.

From these signals, the amount of correction Δ of the pressure setting value of the pressure holding process is calculated.
p, is calculated and output to the main controller 12.

A console 14 for an operator to set optimal molding conditions is connected to the main controller 12, and setting inputs are outputted to the resin condition controller 11 as molding condition signals through the main controller 12. The main controller 12 controls the set values set by the operator through the console 14 for the resin injection speed and the resin pressure during the pressure holding process, with the set value corrected by the set value correction amount Δp due to fluctuations in environmental conditions as a target value. I do.

The above control system is realized by a microcomputer.

Next, a resin state control method will be explained.

First, the locus on the pvT diagram during molding is determined.

For this purpose, an estimated value of the resin temperature is required. It is expressed by the following formula.

TM (t)−Tw +a+ (TMI TW)
*exp(-t/τ1) +a2 (TMI Tw) *exp(-t/τ2) (3) Here, TMI
is the measured value or set value of the resin temperature at the start of injection, and τ1
is the set value of the injection time, and τ2 is the set value of the injection + pressure holding time. al+a2 is a constant. However, as shown in FIG. 1, if a resin temperature detector is provided and the resin temperature T can be directly measured, calculation of equation (3) becomes unnecessary.

The relationship between this equation and pvT of equation (1) and the detected pressure value p
(t), the pvT locus during molding can be calculated as shown in FIG. In FIG. 4, the solid line shows the trajectory during the first molding immediately after the start of molding, and the broken line shows the trajectory during the 10th molding. This is a considerably distorted trajectory compared to the ideal case shown in FIG.

The reason for this is, as mentioned above, the difference that occurs because unidistributed trajectories are combined into one trajectory.

In the 10th molding, the mold temperature has increased compared to the 1st molding, so the environmental conditions have changed, and the resin temperature calculated by equation (3) has changed, so the trajectory is like the broken line in Figure 4. Changes to Therefore, this deviation will not disappear unless the pressure cover pattern is changed and a new set value is calculated.

Corrections are made based on the difference in trajectory shown in Figure 4 (deviation area - calculation method will be described later) and the injection speed pattern set by the operator (Po
=Ps). The trajectory is at time tl+ “2+
3, and for each section, as shown in FIG. 3, the point Q, which was initially set by the operator, is shifted in the time axis direction to correct the set value.

When the difference between the initial (to tl) trajectories is large.

Depending on the value, point Q is moved to Q1' or Q1'. The amount of movement (shift time of the pressure holding process) is Δt, which is inversely proportional to the value of Δ2 in the injection speed pattern shown in FIG. That is, since Δ2 is a set value of the injection speed set to prevent an increase in the stress distribution due to a rise in pressure, when this value is large, it is better not to change the set value of the pressure too much.

When the difference in the trajectory in the middle period (t□-t2) is large, Q2 is moved to 02' or Q2'' depending on the value.The amount of movement is Δt2, which is in the middle of the injection speed pattern shown in Fig. 2. It is made proportional to the slope a of the straight line P3P4.a indicates the flow characteristics of the resin, and when α is large, the viscosity of the resin is high or the resistance of the flow path is large, so p must be adjusted significantly.
This means that vT control has no effect. When α is zero or a negative value, even a small modification is sufficiently effective.

When the difference between the trajectories at the final stage (t2 ti) is large, Q3 is moved to 03' or Q3' depending on the value.

The correction amount is Δt, and when Δ1 of the injection speed pattern shown in Figure 2 is large, the flow in the gate part tends to be disturbed greatly, and the gate is likely to break or overpack even during pressure holding. The amount of correction should be small.

Based on the above concept, the operator sets the molding conditions to search for a good molded product, and then uses the data to modify the pressure setting value.

The resin condition control device 11 of the present invention operates according to the procedure shown in FIG.

Before explaining the procedure, the characteristics of the resin are expressed by a pvT diagram as shown in equation (1), but what is ultimately required is the specific volume V. On the other hand, only pressure p and temperature T can be measured.
is calculated from various setting parameters according to equation (3). In the present invention, the pvT trajectory during molding is limited to a limited area.

It can be thought of as pv snow RT (4), so modify it.

Let k-v/R-T/p(5) be the control amount. The pressure p is the measured time pattern p
(t), and for the temperature T, TM(t) of equation (3) is used. In FIG. 5, ko (t) is a time pattern during molding of a non-defective product immediately after the molding conditions are set, which is calculated using this equation. Also, k (t) is the calculated time pattern when the environmental conditions change after that.

S,,S2. S3 is a time pattern k as shown in FIG. (
tl+ calculated from the difference between 1) and k(t)
t2+ is the deviation area for each section of 9.

Then, the shift time Δj++ Δi2+ Δt3 is calculated according to the following equation.

Δt 1 = KI S+ / (1+Δ2) (
6) Δt2−2 S2 (1+α) (7
)Δt,−,S,/(1+Δ,) (8) where, , 2. is a coefficient for converting into time, and α is the slope of the straight lines P and P in FIG. however,
When the slope is negative, it is set as α-0.

Δ is the length of straight lines P and P2, and when +P2 is above Pl, Δ is -0. Δ2 is P4 and P.

If it is above +P'i or P4, it is set as Δ2-0. Further, the correction amount Δp of the pressure set value is determined at point Q1 as shown in FIG. Δ”1+Δt2.Δt3 for Q2 and Q3
Shift the time and decide.

Referring to FIG. 5, the operator makes preparations such as raising the temperature of the mold 104 and the heating cylinder 100, and then inputs the injection speed and holding pressure settings from the console 14 to try molding. The quality of the molded product is determined by visual inspection (Step Sl).

By repeating correction of the setting values and molding several times, the optimum setting values are determined according to the shape of the molded product and the type of resin. This optimal set value is sent to the resin condition control device 11 (step S2). The resin pressure during molding (step S3) is determined by the set value obtained by the operator's experience and intuition in this way.

Using the detected temperature value, equations (3) and (5) are calculated to calculate a time pattern (function) ko(t) (step S4). This time pattern k.

<1> is sent to the resin condition control device 11.

After that, each time molding (step S5) is performed, equation (3), (5
) to calculate the time pattern k(t) (step 56) L, the time pattern k calculated during the previous molding as shown in FIG. (1) and the deviation area S, , S2. s.

is calculated (step S7).

In step 8, the deviation area Sll S2. S3 and Δ1
．． A shift time Δtl+Δj2+Δt3 is calculated from α and Δ2 using equations (6) to (8).

The resin condition control device 11 calculates the correction amount Δp of the pressure setting value and sends it to the main control device 12 (step S9). The main controller 12 controls the injection speed and resin pressure based on the correction amount Δp.

FIG. 7 shows the weight change of the molded article obtained according to the present invention from the start of molding, and it can be seen that it is much more stable than the conventional example shown in FIG. 9.

As is clear from the above description, one feature of the present invention is as follows.

Based on the set values set by the operator for molding and the molding pattern (detected values of temperature and pressure) during molding of a good product, a simple function is used to calculate the correction amount Δp of the set values to stabilize quality against fluctuations in environmental conditions. The reason is that it is calculated sequentially.

In order to configure the control device of the present invention, a mold temperature detector and a resin temperature detector are required to detect changes in environmental conditions, but other control devices and setting devices can be used with existing injection molding machines. You can use what is equipped with. Moreover, the operator.

There is no need to set or adjust parameters for resin condition control, and the correction amount for control is automatically determined during normal operation.

(Effect of the invention) The effect of the present invention will be explained while comparing it with a conventional example.

In conventional pvT control, as shown in Fig. 12, the pressure setting value is basically corrected so that the specific volume v is constant, or
For this purpose, parameters of equation (1) are required for each resin. Furthermore, in the case of a molded product having a complicated shape, a simple trajectory as shown in FIG. 12 is often not achieved. On the other hand, in the present invention, since the time pattern k (t) in equation (5) is calculated only from measured values or normal set values, parameters related to pvT are not directly required. The patterns we are considering include even complex ones, as shown in Figure 6. Furthermore, since not only the total -j value but also the operator's injection speed setting value is used to correct the pressure setting value, information on resin flow characteristics for complex shapes is indirectly supplemented. Therefore, the range of molded products to which it can be applied is considerably wider than in the past.

Comparing the number of specific parameters, in conventional pvT control, the parameters are π and ω in equation (1).

R and a@lIns of formula (2) had to be prepared for each type of resin and each molded product. Against this.

In the present invention, ayo+a2 and (6) to (8) in formula (3)
2. 3 must be prepared, but it can be determined experimentally using the molded product shown in Fig. 15 and then kept constant thereafter. That is, when changing the type of resin or molded product, the operator re-determines the set values each time, and the parameters are automatically changed using the changed set values.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an embodiment of the present invention, Fig. 2 is a diagram for explaining an example of injection speed setting applied to the present invention, and Fig. 3 is a holding pressure applied to the present invention. FIG. 4 is a diagram for explaining an example of pressure setting; FIG. 4 is a diagram for explaining changes in characteristics over time in pvT control; FIG. 5 is a flowchart for explaining the control operation of the present invention; FIG. 7 is a diagram showing an example of the time pattern calculated in the present invention, FIG. 7 is a diagram showing the weight change of a molded product molded according to the present invention, and FIG. Figure 9 shows the change in mold temperature, Figure 9 shows the weight change of a molded product molded using a conventional device, Figure 10 shows the schematic configuration of an injection molding machine, and Figure 11 shows injection molding. A diagram schematically showing the molding operation in the machine, Figure 12 is a v-T diagram for a molded product with a simple shape, Figure 13 is a diagram showing changes in resin temperature over time, and Figure 14 is a pressure setting value. FIG. 15 is a diagram for explaining the flow of resin in a plate-shaped molded product, and FIG. 16 is a v-T diagram for the molded product shown in FIG. 15. In the figure, 100 is a heating cylinder, 101 is a screw, 10
2 is an injection cylinder, and 103 is a rotational drive system. 14 is a mold, and 105 is a cavity. Agent (7783) Patent attorney Noriyasu Ikeda Mimi, Kai Ryo 2 Figures Sales 3 Figures Kan 6 Figures 7 Figures of shape and quantity No. 9 figures / Lll) 笥 IQ Figure Semi 11 Figures % 12 Figures Ryo j 4 Figures Ryo Figure 15 V2 TE Ryo i6 Figure

Claims (1)

[Claims] (1) A means for inputting molding conditions such as injection speed and resin pressure during holding pressure, which includes a mold temperature detector, a resin temperature detector, and a resin pressure detector as resin condition detection means, and the input means After molding is performed to obtain a good molded product based on the molding conditions set in , a time function curve is calculated based on a predetermined calculation formula using the detection signals from each of the detectors. After that, the time function curve is calculated each time molding is performed, and the deviation area between the time function curve and the time function curve calculated in the previous molding cycle is calculated to calculate the amount of pressure setting value correction in the pressure holding process. controlling the injection speed using a control device, the molding conditions and the pressure setting value correction amount;
1. A control device for an injection molding machine, comprising a main control device for controlling resin pressure, etc.