JPH0246963A - Method of controlling die temperature of die casting - Google Patents

Abstract

PURPOSE:To shorten the time required for test casting by measuring the temp. of a die and controlling the injection speed of the molten metal to be packed into the cavity of the die according to the measured die temp. CONSTITUTION:Temp. measurement is executed by a die temp. measuring instrument 8 via a temp. sensor 8a disposed to the die 1 when the machine starts. A controller 11 compares the measured temp. value and the set temp. value previously inputted thereto and judges whether normal casting or test casting from the value. The controller commands a speed controller 20 to increase an injection speed and to change the advance speed of a plunger tip 7 of an injection cylinder 6 in case of the test casting. The controller outputs a test casting signal to announce the test casting to an operator. The molten metal is injected at the injection speed of a prescribed pattern. The die is heated up to an adequate temp. in the test casting in this way and the time required for the test casting is shortened. The timing for the change from the test casting to the normal casting is exactly detected and the fraction defective is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a mold temperature control method for rapidly raising the mold temperature when the mold temperature is too low in die casting.

In conventional die casting manufacturing, conditions such as molten metal temperature, pouring time, and pouring pressure greatly affect the casting product lfL and defective rate. In particular, if the temperature of the mold is lower than the set proper temperature, there is a risk that dimensional defects in the casting, poor rotation, etc. will occur. Therefore, in order to prevent the occurrence of casting defects, methods of preheating the mold with a mold drying burner, etc., or carrying out test tests, are used to adjust the mold temperature using the heat of the molten metal. A method is commonly used to increase the

Problems to be Solved by the Invention However, among the methods described above, in the case of the former method of preheating using a mold temperature controller, etc., the equipment becomes large and takes up space, and it is not necessary to use a mold temperature controller, etc. There was a problem in that this required additional equipment costs.

In the case of the latter method, which involves test casting, it does not increase the size and does not incur extra costs, but it is not possible to warm the mold to the appropriate temperature before casting, and therefore, at the beginning of the casting work, Before carrying out the actual casting of the product, it was first necessary to carry out a test casting. Therefore, it is desirable to finish this test carry-in in a short time and switch to the main casting, but in the case of the conventional method, the injection speed at which the molten metal is injected into the mold cavity of the die-casting machine is lower than the test casting. The problem was that test casting took a long time until the mold reached the appropriate temperature for casting, since the casting speed was the same as the actual casting of the product.

In addition, the number of test casting shots required to raise the mold temperature to the appropriate temperature varies depending on the casting conditions, making it difficult to judge the end time of the test casting and relying on the worker's discretion to make the decision. was the current situation.

However, they misjudged when the mold should reach the appropriate temperature, that is, when to finish the test casting and switch to the actual casting of the product. Since main casting is performed in a state where the incidence of defects is high, there is a problem that the defect rate of the product is high. On the other hand, if the switching time is too slow, test casting will continue longer than necessary, resulting in an increase in the number of unnecessary test castings.

This illumination was achieved under the technical auspices mentioned above.
It is an object of the present invention to provide a mold temperature control method in die casting that can rapidly raise the mold temperature through test casting and accurately determine the end time of test casting, that is, the timing of switching to main casting.

Means to Solve the Problem As a means to solve the above problem, Kitamon's method measures the temperature of the mold during die casting.
The present invention is characterized by a port that controls the injection speed of the molten metal filling the cavity of the mold according to the measured mold temperature.

Operation By adopting the above method, when performing casting, the temperature of the mold is first measured, and it is determined from this measured value whether or not test casting is necessary. In other words, if the measured value of the mold temperature is lower than the optimum casting temperature, it is determined that the mold needs to be warm during test casting, and the molten metal is injected at a faster speed than during actual casting to fill the cavity of the mold. . Therefore, by completing the casting in the furnace time, the upper temperature limit of the mold becomes faster and the time required for test casting is reduced.
It is also possible to reduce the number of test castings required to raise the temperature of the mold to the appropriate casting temperature.

In addition, the mold temperature is measured each time during pre-filling to determine whether test casting is necessary or not, so when the mold temperature rises to an appropriate temperature and it is time to finish test casting, By accurately capturing the timing, the process can be switched to actual casting of the product.

Embodiment Hereinafter, one embodiment of this north gate will be explained based on FIGS. 1 to 6.

Figure 1 shows the configuration of a die casting machine that performs die casting using the mold temperature control method of this embodiment.A mold 1 consists of a movable mold 2 and a fixed mold 3. A cavity 4 is formed by the mold 3. Further, an injection sleeve 5 is provided at the lower side of the fixed mold 3, and its end 5a communicates with the lower end of the cavity 4, so that the injection sleeve 5 is approximately horizontal. , are fitted to be slidable in the axial direction, and by moving the plunger tip 6 forward (rightward in FIG. 1), the molten metal in the sleeve 7 is forced into the cavity 4. Also, in the mold 1, a temperature sensor 8a of a mold temperature measuring device 8 is installed in the cavity 4.
The mold temperature measuring device 8 measures the mold temperature at the portion where the temperature sensor 8a is installed and outputs the measured value.

On the other hand, the control system of the die casting machine compares the mold temperature measurement value input from the mold temperature set value @8 with the mold temperature set value input in advance to determine whether it is test casting or not. A control device @9 that judges whether it is casting or not and outputs a command based on the result of this judgment, and an injection device that controls the injection speed of molten metal by the injection cylinder 6 based on the signal output from the control device 9. It is comprised of a speed control device 1o, and a die-casting machine control device 11 that controls starting and stopping of this die-casting machine and sends signals to the control device 9 when starting and stopping the die-casting machine.

In addition, the control device 9 makes a judgment that if the temperature of the mold is lower than the temperature suitable for casting, the incidence of casting defects is high. The shot casting is determined to be test casting, and a command is sent to the injection speed control device @10 to increase the injection speed. By making the injection speed by the injection cylinder faster than the injection speed during the main casting of the product, the filling of the molten metal into the cavity 4 is completed faster than during the main casting, and the molten metal, which is at a higher temperature than during the main casting, is transferred to the mold 1. The temperature of the mold 1 is rapidly raised by the heat transferred from the molten metal to the mold 1.

Therefore, the temperature of the mold 1 is increased by the test casting, and after reaching the appropriate temperature, the actual casting of the product is performed.

Figure 6 shows the change in molten metal temperature during filling.
Point 8 is the filling completion point during main casting, and the melt fA at that time
The temperature is T2. Further, point A is the filling completion point during test casting, and the melting temperature at that time is TI. Therefore, as can be seen from this figure, TI > T2, and the mold 1 can be filled with high-temperature molten metal during test casting.

Further, FIG. 2 shows a flowchart of a control program installed in the m control device 9, and control during vI manufacturing will be explained based on this flowchart.

When the program starts, first in step 1, a starting signal outputted from the die-casting machine controller 11 at the time of starting the die-casting machine is detected, and if the starting signal is not detected, detection is repeated until it is detected. Then, when the activation signal is detected, step 2
Proceed to.

Proceeding to step 2, the temperature sensor 8 disposed in the mold 1
The mold temperature is measured by the mold temperature measuring device 8 via a, and then in step 3 the control device 11 uses the measured mold temperature measurement value Tk and the suitability of the mold inputted in advance. The temperature, that is, the mold temperature set value TS is compared, and for example, if the mold temperature is higher than the set temperature <Tk≧TS
In this case, it is determined that this is not test casting but actual product casting, and the process returns to step 1 and waits until the next activation signal is output. Also, the mold temperature is lower than the set temperature.
If k < TS, it is determined that test casting is to be performed and the process proceeds to step 4.

In step 4, a command is issued to the injection speed control device 10 to speed up the injection speed, and this command causes the injection speed control device @10 to speed up the bending speed of the plunger tip 7 of the injection cylinder 6 for test casting. change. Next, when proceeding to step 5, a test casting signal is output, and for example, this signal lights up an indicator light to notify the operator that the current casting is test casting, and the process returns to step 1. Wait until the next activation signal is detected.

On the other hand, the injection cylinder 6 injects the molten metal at a predetermined pattern of injection speed,
The basic pattern of this injection speed is shown in Figure 3 with χ
As shown by the solid line in the diagram with the injection time on the axis and the displacement position of the plunger tip on the y-axis, there is a low-speed section from injection start point 0 to point Pa, and a low-speed section from point Po to point Qo. It consists of a high-speed section. Moreover, this basic pattern can be changed by the injection speed control device 10, and the control device @
As an example of changing the pattern when increasing the injection speed for test casting based on the command from 9, as shown by the broken line in the diagram in Figure 3, the low speed section from point O to point Pa of the basic pattern is changed to Speed up and O-P+ -
As shown in the first pattern with IQI and the dashed line in the diagram in Figure 4, the low-speed section from point O to point PO in the basic pattern is shortened and the transition to the high-speed section is brought forward to increase speed. The second pattern is O→P2→Q2,
Alternatively, as shown by the broken line in the diagram of FIG. 5, there is a third pattern in which the high-speed section from point Po to Qo of the basic pattern is sped up to 0→P1→Q3, and a third pattern of these first... Second. There are various patterns (not shown) that suitably combine the third patterns. By changing the injection speed pattern from the basic pattern to these patterns, the injection speed of the current is made faster than during the actual rusting, and the molten metal is filled into the cavity of the mold in a short time. Therefore, the amount of temperature rise in the mold per shot increases, the number of test casting shots required for the mold to rise to the appropriate temperature for construction decreases, and the time required for test casting is shortened. .

In addition, the mold temperature is measured every time when performing the pouring process to determine whether test casting is necessary or not. It is possible to accurately grasp the situation and switch to regular casting. Therefore, by being able to accurately determine when to switch from test casting to main casting of products, it is possible to prevent the switching timing from being delayed or too early, to minimize the number of test castings, and to prevent an increase in defective products. .

As described in detail, the mold temperature control method for die casting manufacturing of the present invention measures the temperature of the mold during die casting, and adjusts the temperature of the mold according to the measured mold temperature. By controlling the injection speed of the molten metal filling the cavity, the mold can be heated to the appropriate temperature with a small number of test castings, so the time required for test casting can be shortened. In addition, since the timing of switching from test casting to main casting can be accurately determined, it is possible to reduce the defective rate of products and to minimize the hanging of test products.

[Brief explanation of the drawing]

Figures 1 to 6 show an example of this method. Figure 1 is an explanatory diagram showing the combination of a die-casting machine, Figure 2 is a flowchart of a control program, and Figure 3 is a low-speed section. Fig. 4 is a diagram showing an injection pattern with a shortened low-speed section, Fig. 5 is a diagram showing an injection pattern with a high-speed section sped up, and Fig. 6 is a diagram showing an injection pattern with a shortened low-speed section. FIG. 3 is a diagram showing changes in molten metal temperature. 1...Mold, 2...Movable type, 3...Fixed type,
4... Cavity, 5... Injection sleeve,
6... Cutting cylinder, 7... Plunge ↑/Dep, 8... Mold temperature measuring device, 8a... Temperature sensor, 9... Control device, 10... Injection speed control device , 11...Die casting machine control device. Figure 3

Claims (1)

[Claims] A mold for die-casting, characterized in that when performing die-casting, the temperature of the mold is measured, and the injection speed of the molten metal to be filled into the cavity of the mold is controlled according to the measured mold temperature. Temperature control method.