JPH0371933B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for stabilizing the quality of a die-cast product by stabilizing the temperature of a die in die-casting using die casting.

"Prior Art" The spray device for a die-casting machine disclosed in the conventional Japanese Patent Application Laid-Open No. 60-92046 is equipped with a temperature sensor that detects the mold temperature of a casting mold, and a mold release agent spray or a cooling water spray. Mold temperature data T representative of the casting mold is determined from the temperature data detected by the spray operation control means to be activated and the temperature sensor, and the operating time of the spray operation control means is determined according to this mold temperature data. It merely includes a temperature discrimination control circuit that changes the temperature. The spray device is configured to output temperature discrimination signals TS1 to TS5 corresponding to the temperature range classification to which the mold temperature data T belongs to the timer control circuit 5 in accordance with the mold temperature data T. For example, one mold temperature data Tm corresponds to a certain temperature range.
As long as Tn≦Tm≦Tn+1, a fixed temperature discrimination signal TSm continues to be output, and the mold temperature can only be controlled within a few limited temperature ranges, resulting in poor control accuracy. Ta. In addition, the conventional spray device for a die casting machine disclosed in JP-A-60-92047 uses a temperature sensor that detects the mold temperature of a casting mold and responds to the mold temperature data detected by this temperature sensor. It is merely equipped with a spray controller that controls the spraying time of the mold release agent spray or cooling water spray. In this spray device, the mold temperature of the casting mold is detected by a temperature sensor, and the spraying time of the spray is controlled according to the detected temperature data T. is temperature data T1 to Tn of each part of the casting mold 1 given from thermocouples 21 to 2n, or 1
When the temperature change rate δ, which is the mold temperature before the shot minus the current shot mold temperature, is given, the next spraying time is determined based on the preset relational expression t=f(T) or t=f(δ). Since it is calculated and determined, changes in disturbances (air temperature, cooling water temperature, cooling water flow rate, etc.)
When the mold is changed, the relationship between the mold temperature and the next spraying time changes, making it difficult to put it into practical use and having the disadvantage of poor mold temperature control accuracy.

"Problems to be Solved by the Invention" The present invention has been made to solve the above-mentioned problems, and it is possible to quickly raise the mold temperature to a stable casting temperature that is the set temperature, and also to prevent external disturbances. The purpose of the present invention is to provide a die-casting method that allows the mold temperature to always follow the stable casting temperature well even when there are changes in the mold temperature or changes in the mold, and that can significantly reduce product defects caused by the mold temperature. shall be.

"Means for Solving the Problems" For the above purpose, according to the present invention, the mold temperature is measured for each shot by a temperature sensor provided in the mold, and the mold temperature of the current shot is set as the set temperature. When comparing the stable casting temperature and the mold temperature one shot before, if the current mold temperature of the shot is significantly lower than the stable casting temperature set as the set temperature and is in the waste casting region or unstable casting region, the product will be released from the mold. By setting the timer value to a preset minimum value that does not damage the mold and performing mold release agent spray and/or air blow for a short period of time, the mold temperature is quickly raised to a stable casting temperature, and the current When the mold temperature of the shot is in the stable casting range, compare the current shot mold temperature with the stable casting temperature, and also compare the current shot mold temperature with the mold temperature one shot ago to stabilize the mold temperature. A die casting method is provided which is characterized in that the timer value of the previous shot is increased or decreased to determine the timer value of the next shot so that the timer value of the previous shot can be maintained in the casting region, and the mold release agent spray and/or air blow is performed.

"Operation" According to the above configuration, while the mold temperature of the shot is currently lower than the stable casting temperature and is in the throw away casting region or the unstable casting region, the timer value is set to the minimum value, so the mold is released. Cooling by agent spray and/or air blowing is minimized and the mold temperature is quickly raised to a stable casting region. In addition, if the mold temperature rises to the stable casting region, compare the current shot mold temperature with the stable casting temperature, and compare the current shot mold temperature with the stable casting temperature.
The mold temperature is compared with the mold temperature before the shot, and the timer value for the previous shot is determined by increasing or decreasing the timer value for the previous shot to maintain the room temperature within the stable casting range, and the timer value for the next shot is then sprayed with mold release agent and/or air blowed. Even if there are changes in external disturbances or changes in the mold, the mold temperature will always follow the set stable casting temperature.

The casting state of die casting can be roughly divided into a waste casting region, an unstable casting region, and a stable casting region, as shown in FIG. 2, depending on the mold temperature during casting. The feature of the method of the present invention is that the mold temperature of the current shot is compared with the stable casting temperature, and the mold temperature of the current shot is compared with the mold temperature of one shot before, and the mold temperature of the current shot and the mold temperature of one shot before are compared, and the mold temperature of the current shot and the mold temperature of one shot before are compared, and the mold temperature of the current shot and the mold temperature of one shot before are compared, and the mold temperature of the current shot and the mold temperature of one shot before are compared, and the mold temperature is In the stable casting region, the timer value of mold release agent spray and/or air blow is controlled to the optimum value, aiming at early stabilization of mold temperature and constant stabilization. Next, the operation of the control method in each of the waste casting region, unstable casting region, and stable casting region will be explained.

First, in the waste casting area, the purpose is to raise the mold temperature, not to cast a quality product. Therefore, the timer value for the next shot is set to the minimum value that does not interfere with product release.

In the unstable casting region, the mold temperature has not yet risen sufficiently, but has reached a temperature level at which good products can also be cast. Therefore, the timer value is set to a minimum value that does not cause damage to the mold when releasing the product.

In the stable casting region, the mold temperature is in a region where the highest quality product can be expected to be cast, so the timer value is determined so that the mold temperature does not always deviate from the stable casting temperature. First, the current shot mold temperature and 1
The mold temperature before the shot and the stable casting temperature are compared, and if the mold temperature of the current shot is lower than the stable casting temperature and lower than the mold temperature of one shot before, the timer value for the next shot is decreased. Second, if the mold temperature of the current shot is lower than the stable casting temperature and higher than the mold temperature of the previous shot, the timer time for the next shot is set to 1.
The timer value is set to be the same as before the shot. Thirdly,
The current shot mold temperature is equal to the stable casting temperature, and 1
If the mold temperature is lower than the temperature before the shot, the timer value for the next shot is decreased. Fourth, if the mold temperature of the current shot is equal to the stable casting temperature and higher than the mold temperature of the previous shot, the timer value for the next shot is increased. Fifth, if the mold temperature of the current shot is equal to the stable casting temperature and equal to the mold temperature of one shot before, the timer value of the next shot is made the same as the timer value of one shot before. Sixth, if the mold temperature of the current shot is higher than the stable casting temperature and higher than the mold temperature of the previous shot, the timer value for the next shot is increased.
Seventh, if the mold temperature of the current shot is higher than the stable casting temperature and lower than the mold temperature of the previous shot, the timer value of the next shot is made the same as the timer value of the previous shot.

"Embodiments" Next, the present invention will be specifically described with reference to embodiments shown in FIGS. 1 to 3.

As shown in FIG. 3, a temperature sensor 2 is attached to the aluminum die casting mold 1. As shown in FIG.
The voltage output of the temperature sensor 2 is amplified by a voltage amplifier 3 and introduced into a programmable sequential controller (hereinafter referred to as PC) 20. The PC 20 includes an analog/digital input circuit 4 for converting an analog signal into a digital signal, a temperature comparison circuit 5 for comparing the stable casting temperature as a set temperature and the current mold temperature of the shot as an actual temperature, and a timer. Arithmetic circuit 6 that computes values
, a timer circuit 7 that sends an ON-OFF signal to the valve control circuit, and an electromagnetic valve control circuit 8 that controls the release agent spray time and air blow time. The output of the electromagnetic valve control circuit 8 is introduced into a release agent electromagnetic valve 9 and an air electromagnetic valve 10, and from a release agent nozzle 11 facing the aluminum die-casting mold 1, the output is used to cool the mold and produce the product. A mold release agent is sprayed to aid in mold release, and an air blow is applied to the aluminum die casting mold 1 from an air nozzle 12 to cool the mold and to remove residual mold release agent.

"Operation" In the above configuration, the operation of this embodiment will be explained mainly using the flowchart shown in FIG. The temperature sensor 2 captures the temperature of the aluminum die-casting mold 1 in the form of a voltage value (mV). The captured voltage value is
It is amplified by the voltage amplifier 3 and converted into a digital value by the analog/digital input circuit 4 in the PC 20, and the current mold temperature A of the shot is obtained. The mold temperature A of the current shot is subjected to the following comparison process by the temperature comparison circuit 5.

First, the current mold temperature A of the shot is compared with the minimum casting temperature SL, which is lower than the preset stable casting temperature ST, and the current mold temperature A of the shot is compared to the minimum casting temperature.
If it is lower than SL (A<SL), it is determined that the casting is in the waste casting region, and the spray timer value t1 of the first mold release agent, which is preset as the timer value for the next shot, is obtained. If the current mold temperature A of the shot is equal to or higher than the minimum casting temperature SL (A≧SL), proceed to the next comparison process.

Second, the current shot mold temperature A is the minimum casting temperature
If it is equal to or higher than SL, the mold temperature A is compared with the stable casting region lower limit temperature ST', which is the lower limit of the stable casting region. If the mold temperature A of the current shot is lower than the stable casting region lower limit temperature ST'(SL≦A≦ST'), it is determined that casting is in the unstable casting region, and the preset timer value for the next shot is set. Obtain the release agent spray timer value t2 of 2. The second timer value t2 is the same as or slightly longer than the first timer value t1. On the other hand, the current shot mold temperature A
is higher than the stable casting region lower limit temperature ST'(A>
In ST′), it is determined that the casting is in the stable casting region, and the process proceeds to the next comparison process.

Third, if the current mold temperature A of the shot is equal to or higher than the stable casting region lower limit temperature ST', the mold temperature A is compared with the stable casting temperature ST, and the process proceeds to the next comparison process.

First, the mold temperature A of the current shot is compared with the mold temperature A' of the previous shot. Then, get the timer value as follows. First, if mold temperature A is lower than stable casting temperature ST and lower than mold temperature A' of one shot before (A<ST, and A≦A'), and if mold temperature A is the same as stable casting temperature ST and 1 Mold temperature before shot
If it is smaller than A' (A=ST and A<A'), the timer value t for the next shot is calculated by subtracting the preset increase/decrease time x from the timer value t' for the current shot.
is obtained by the arithmetic circuit 6. Current shot mold temperature A
When is greater than the stable casting temperature ST and the mold temperature A' or more before one shot (A>ST and A≧A'),
And the current shot mold temperature A is the stable casting temperature ST
and is larger than the mold temperature A' of the previous shot (A = ST and A >A'), the timer value t' of the current shot plus the preset increase/decrease time x is calculated for the next shot. The timer value t is obtained by the arithmetic circuit 6. The current shot mold temperature A is the stable casting temperature.
If the mold temperature A′ of the current shot is smaller than ST but larger than the mold temperature A′ of the previous shot, the mold temperature A of the current shot is the stable casting temperature.
If the mold temperature A' of the current shot is larger than ST but smaller than the mold temperature A' of the previous shot, or if the mold temperature A of the current shot is the same as the stable casting temperature ST and the mold temperature A' of the previous shot, the timer of the current shot is Obtain the timer value t for the next shot, which is the same as the value t'.

The timer value t for the next shot obtained as described above is taken into the timer circuit 7 as a set value, and the output timing of the electromagnetic valve control circuit 8 is controlled. The solenoid valve control circuit 8 opens the mold release agent solenoid valve 9 and the air solenoid valve 10 so that the mold temperature A is a stable casting temperature within the stable casting region.
The mold release agent spray and air blow are performed on the die-casting mold 1 from the mold release agent nozzle 11 and the air nozzle 12 so that ST is obtained. Mold release agent spray was originally used for die casting mold 1.
The purpose is to assist in releasing the product from the mold, but it also has the function of cooling the die casting mold 1.

"Other Examples" In the examples described above, the timer value including the mold release agent spray and air blow was controlled, but even if only the mold release agent spray time or the air blow time was controlled, the mold Temperature can be controlled.

According to the method of this embodiment, by comparing the current mold temperature of the shot with the stable casting temperature, it is possible to distinguish between the waste casting region, the unstable casting region, and the stable casting region. From a judgment standpoint, all die-cast products in the waste casting area are judged to be defective, and die-cast products in the unstable casting area are judged to be priority check items.
Furthermore, if the die-cast products in the stable casting region are determined to be sampling check products and the die-cast products are classified, there is an advantage that the time required to determine the quality of the die-cast products can be shortened.

``Effects'' As described above, the die casting method of the present invention measures the mold temperature for each shot using a temperature sensor installed in the mold, and also achieves a stable casting temperature using the current mold temperature of the shot as the set temperature. If the current mold temperature of the shot is significantly lower than the stable casting temperature set as the set temperature and is in the waste casting region or unstable casting region, the mold temperature will be lowered when releasing the product. By setting the timer value for the next shot to a preset minimum value that does not cause damage to the mold and performing mold release agent spray and/or air blow for a short period of time, the mold temperature is quickly raised to a stable casting temperature, and the current If the mold temperature of the shot rises to the stable casting region, compare the current mold temperature of the shot with the stable casting temperature, and
The mold temperature of the current shot is compared with the mold temperature of one shot before, and the timer value of the previous shot is determined by increasing or decreasing the timer value of the previous shot so that the mold temperature can be maintained within the stable casting range, and the timer value of the next shot is determined. /Or because air blowing is performed, the timer value is set to the minimum value while the shot mold temperature is lower than the stable casting temperature and is in the waste casting region or unstable casting region, so the mold is not sprayed with release agent. and/
Alternatively, cooling by air blowing is minimized and the mold temperature is quickly raised to the stable casting region, and if the mold temperature rises to the stable casting region, the current mold temperature of the shot is In addition to comparing the stable casting temperature, the mold temperature of the current shot and 1
The mold temperature before the shot is compared, and the timer value for the previous shot is determined by increasing or decreasing the timer value for the previous shot in order to maintain the mold temperature within a stable casting range, and the mold release agent spray and/or air blow is performed. Even if there are changes in external disturbances or changes in the mold, the mold temperature always follows the set stable casting temperature.
This has the excellent effect of significantly reducing defects in die-cast products due to mold temperature.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing the operation of an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the casting area divided based on mold temperature, and Fig. 3 is a block diagram showing the configuration of the apparatus of the embodiment. It is. ...Sacrificial casting area, ...Unstable casting area, ...Stable casting area, 1...Aluminum die casting mold, 2...Temperature sensor, 3...Voltage amplifier, 9...Solenoid valve for mold release agent , 10... Solenoid valve for air, 11... Nozzle for mold release agent, 12...
Air nozzle, 20...Programmable sequential controller.

Claims (1)

[Claims] 1. The mold temperature for each shot is measured using a temperature sensor installed in the mold, and the mold temperature of the current shot is compared with the stable casting temperature set as the set temperature, and the mold temperature of one shot before is compared. If the current mold temperature of the shot is significantly lower than the stable casting temperature set as the set temperature and is in the dump casting region or unstable casting region, the temperature must be set in advance to a level that will not damage the mold when releasing the product. By setting the timer value to the minimum value set and performing mold release agent spray and/or air blow for a short period of time, the mold temperature can be quickly raised to a stable casting temperature. If the mold temperature of the shot is currently in the stable casting range, In addition to comparing the mold temperature of the current shot with the stable casting temperature, the mold temperature of the current shot is compared with the mold temperature of one shot before, and the timer value of the previous shot is set to maintain the mold temperature in the stable casting range. A die casting processing method characterized by increasing or decreasing a timer value for the next shot, and spraying a mold release agent and/or blowing air.