JP2638110B2 - Mold temperature control method in die casting - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold temperature control method for rapidly increasing a mold temperature when die temperature is too low in die casting.

Conventional technology In die casting, the temperature of the molten metal, casting time,
Conditions such as casting pressure greatly affect the quality and defective rate of the casting. In particular, if the temperature of the mold is lower than the set appropriate temperature, there is a possibility that a dimensional defect of the casting, a run-out defect or the like may occur. Therefore, as a method of adjusting the mold temperature to prevent occurrence of casting defects, a method of preheating the mold with a mold temperature controller or a gas burner, or a test casting is performed, and the mold temperature is controlled by the heat of the molten metal. Is generally performed.

Problems to be Solved by the Invention However, among the above-mentioned methods, in the former case in which preheating is performed using a mold temperature controller or the like, the apparatus is increased in size and takes up space, and a mold temperature controller or the like is used. Therefore, there is a problem that the equipment cost is extra.

In the case of the latter method of test casting, the mold does not increase in size and does not require extra cost, but the mold cannot be kept at an appropriate temperature before casting.
At the beginning of the casting operation, before the main pouring of the product,
First, it was necessary to perform test casting. Therefore,
It is desirable to terminate the test casting in a short time and switch to the main casting.However, in the case of the conventional method, the casting operation is performed under the same casting conditions as during the main casting of the product during the test casting. However, there is a problem that it takes a long time to perform test casting until the mold reaches a temperature suitable for casting. In addition, since the number of shots of test casting required to raise the temperature to an appropriate mold temperature is not constant depending on the casting conditions, it is difficult to determine the end time of test casting, and the determination depends on the intuition of the operator. Was the current situation.

However, when the mold is at an appropriate temperature, i.e., when the test casting is terminated and the timing of switching to the main casting of the product is incorrect, if the timing of switching to the main casting is too early, the mold is insufficiently heated and the casting failure is caused. Since the main pouring is performed in a state where the incidence rate is high, there is a problem that the defective rate of the product increases. Conversely, if the switching time is too late, the test casting is continued for an unnecessarily long time, and there is a problem that the number of unnecessary test castings increases.

The present invention has been made under the above-mentioned technical background, and a die casting capable of quickly raising the mold temperature by test casting and accurately grasping the timing of the end of the test casting, that is, the timing of switching to the main casting. It is an object of the present invention to provide a method of controlling a mold temperature in casting.

Means for Solving the Problems As a means for solving the above problems, a mold temperature control method in die casting according to the present invention includes forming a dummy cavity in a place other than a cavity of a product part of a mold, and forming the dummy cavity. By opening and closing the communication part to the cavity, when performing die casting, by measuring the temperature of the mold, by opening and closing the communication part to the dummy cavity according to the measured mold temperature It is characterized in that the volume of the entire cavity is changed, and the amount of the molten metal to be filled is increased or decreased in accordance with the change in the volume of the cavity.

Action By adopting the above method, when performing casting,
First, the temperature of the mold is measured, and it is determined from this measured value whether test casting is necessary. That is, when the measured value of the mold temperature is lower than the proper casting temperature, it is determined that the temperature of the mold is required to be raised by test casting, and the communication portion with the dummy cavity of the mold is opened, and the amount of hot water is increased. To control. Therefore, as the amount of the molten metal filled in the mold increases, the temperature of the mold rises faster, the time required for test casting decreases, and test casting for raising the mold to an appropriate casting temperature is performed. The number of times can be reduced. In addition, when performing casting, the mold temperature is measured each time to determine whether or not test casting is necessary. It is possible to switch to the final casting of the product by properly capturing it.

Embodiment An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the configuration of a guy casting machine that performs a die casting structure by performing the mold temperature control method of this embodiment. A mold 1 is composed of a movable mold 2 and a fixed mold 3. A cavity 4 is formed by the fixed mold 3. An injection sleeve 5 is provided on the lower side of the fixed mold 3.
One end 5a thereof is provided substantially horizontally in communication with the lower end of the cavity 4. A plunger tip 7 of an injection cylinder 6 is fitted in the sleeve 5 so as to be slidable in the axial direction. By moving the plunger tip 6 forward (to the right in FIG. 1), the molten metal in the sleeve 7 is pressed into the cavity 4. A hot water supply port 5c is opened in the upper part on the other end 5b side of the injection sleeve 5, and the molten metal is supplied from the hot water supply device 8 into the injection sleeve 5 through the hot water supply port 5c.

The mold 1 has a temperature sensor 9a of the mold temperature measuring device 9.
Is provided at a main portion near the cavity 4, and the mold temperature measuring device 9 measures the mold temperature at the portion where the temperature sensor 9a is provided, and outputs the measured value. ing.

Further, the mold 1 is formed with an auxiliary runner 10 which is a dummy cavity. As shown in FIGS. 2 and 3, the auxiliary runner 10 is formed at a portion outside the cavity 4 of the product part and between the movable mold 2 and the fixed mold 3. An opening / closing pin 11 is provided at the base end (the lower side in FIG. 3). When the pin 11 is driven forward by the hydraulic cylinder 12 (to the left in FIG. 3), it closes the entrance of the auxiliary runner 10 and is driven by the hydraulic cylinder. When it is retracted (rightward in FIG. 3), the entrance of the auxiliary runner 10 is opened, the volume of the entire cavity is increased, and the flow of molten metal into the auxiliary runner 10 is allowed. .

On the other hand, the control system of the die casting machine compares the mold temperature measured value input from the mold temperature measuring device 9 with the previously set mold temperature set value, and determines whether the test casting is performed or the main casting is performed. Is determined, and
A control device 13 that outputs a command based on the result of this determination,
A hot water supply control device 14 for controlling the hot water supply amount based on a signal output from the control device 13; and a start and stop of the die casting machine, and a signal to the control device 13 at the time of start and stop. And a die-casting machine control device 15 for sending the same.

Also, the judgment by the control device 13 is that if the temperature of the mold is lower than the temperature suitable for performing casting, the incidence of casting defects is high, so that the cast product is excluded from the product as a test cast product. It is determined that shot casting is test casting.

Then, when it is determined that test casting is performed, the hydraulic cylinder
A command is sent to 12 and the opening / closing pin 11 is retracted to make the auxiliary runner 10
Of the molten metal supplied by the hot water supply control device 14 into the sleeve 5 from the time of the main casting of the product, that is,
The hot water supply device 8 is controlled so as to increase the amount of molten metal by the same amount as the increase in the cavity volume, the amount of molten metal filled in the mold 1 is increased, and the portion of the auxiliary runner 10 is also filled with molten metal. Become like

Therefore, the amount of heat transferred from the increased amount of molten metal to the mold 1 is increased, so that the amount of temperature rise of the mold 1 for each test casting is increased. The time required for test pouring is also reduced.

FIG. 4 is a graph showing the relationship between the number of shots and the mold temperature when the mold temperature control method of this embodiment is performed and when the casting is performed by the conventional test casting method. When test casting was performed by the method, a non-defective product was obtained in the eighth shot, whereas in the present embodiment, the mold was sufficiently heated by the three shots of the test casting, and the fourth shot was used. A good product could be obtained from

FIG. 5 shows a flowchart of a control program installed in the control device 13, and the control during casting will be described based on this flowchart.

When the program starts, first, in step 1, a start signal output from the die casting machine control device 15 at the time of starting the die casting machine is detected. If the start signal is not detected, detection is repeated until the start signal is detected. When an activation signal is detected, step 2 is executed.
Proceed to.

Proceeding to step 2, the temperature sensor disposed on the mold 1
The mold temperature is measured by the mold temperature measuring device 9 via 9a, and then in step 3, the control device 13 transmits the measured mold temperature measured value Tk and the appropriateness of the previously inputted mold. The temperature is compared with the mold temperature set value Ts,
For example, when the mold temperature is higher than the set temperature and Tk ≧ Ts,
It is determined that it is not the test casting but the main casting of the product, and the process returns to step 1 and waits until the next start signal is output. If the mold temperature is lower than the set temperature and Tk <Ts, it is determined that test casting is performed, and the process proceeds to step 4.

In step 4, a command is sent to the hot water supply device 8 to increase the amount of hot water, and in step 5, a command is sent to the hydraulic cylinder 12, and the opening / closing pin closing the entrance of the auxiliary runner 10 is opened. 11 is driven backward and the auxiliary runner 10
Communicate.

Then, proceeding to step 6, a test casting signal is output. For example, by turning on an indicator light by this signal, the operator is informed that the casting currently being performed is test casting, and the process returns to step 1 to return to the next step. And waits until a start signal is detected.

In addition, when performing casting, the mold temperature is measured each time to determine whether or not test casting is necessary. It can be accurately captured and switched to main casting. Therefore, the timing of switching from the test casting to the main casting of the product can be accurately grasped, so that the switching time can be prevented from being delayed or too early, the test casting can be minimized, and the increase in defective products can be prevented. .

Effect of the Invention As described above, the die temperature control method in die casting according to the present invention forms a dummy cavity in a place other than the cavity of the product part of the die, and opens and closes a communication part to the dummy cavity. As possible,
When performing die casting, the temperature of the mold is measured, and the communication portion to the dummy cavity is opened and closed according to the measured mold temperature, thereby changing the volume of all the cavities and changing the volume of the cavity. Since the amount of molten metal to be filled is adjusted according to the change in volume, the mold can be raised to an appropriate temperature with a small number of test castings.
The time required for test casting can be reduced. In addition, since the timing of switching from test casting to main casting can be accurately grasped, there is an effect that the defect rate of products can be reduced and the amount of test castings can be minimized.

[Brief description of the drawings]

1 to 5 show an embodiment of the method of the present invention. FIG. 1 is an explanatory view showing the structure of a die casting machine, FIG. 2 is a cross-sectional view of an auxiliary runner, FIG. FIG. 4 is a longitudinal sectional view of the auxiliary runner, FIG. 4 is a graph showing the relationship between the number of shots and mold temperature, and FIG. 5 is a flowchart of a control program. 1 ... mold, 2 ... movable mold, 3 ... fixed mold, 4 ... cavity, 5 ... injection sleeve, 6 ... injection cylinder,
7 plunger tip, 8 hot water supply device, 9 mold temperature measuring device, 9a temperature sensor, 10 auxiliary runner, 11
…… Opening pin, 12 …… Hydraulic cylinder, 13 …… Control device,
14 ... Hot water supply control device, 15 ... Die casting machine control device.

Continuation of the front page (56) References JP-A-1-186256 (JP, A) JP-A-61-119366 (JP, A) JP-A-59-64149 (JP, A) JP-A-62-85916 (JP, A) , A) JP-A-62-199254 (JP, A)

Claims (1)

(57) [Claims] 1. A die cavity is formed in a place other than a cavity of a product part of a mold, and a communicating part with the dummy cavity is made openable and closable so that the temperature of the mold is reduced when performing die casting. By measuring and opening and closing the communication part to the dummy cavity according to the measured mold temperature, the volume of all cavities is changed, and the amount of molten metal to be filled is increased or decreased according to the change in the volume of the cavity. A die temperature control method in die casting.