JP3605499B2 - Mold temperature control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a mold having temperature detecting means for detecting a mold temperature of a casting mold, and control means for controlling a flow rate of cooling water for cooling the mold based on the detected mold temperature. Mold temperature control device.
[0002]
[Prior art]
Since the temperature of the casting mold rises due to injection of a high-temperature molten metal, cooling water is supplied to the inside of the casting mold to achieve cooling. The following are known as such mold temperature control devices.
[0003]
Japanese Patent Laying-Open No. 57-97838 discloses a method in which water supply is started when a mold temperature reaches a water supply start temperature, and water supply is stopped when the mold temperature reaches a water supply stop temperature. That corrects the water supply stop temperature based on a deviation between the temperature and the target temperature.
[0004]
Japanese Patent Publication No. Hei 2-28416 discloses that a mold temperature at the start of pouring is measured, and a fixed amount of cooling water determined based on the level of the mold temperature at the start of pouring is supplied to casting 1 What is supplied over a cycle is described.
[0005]
Japanese Patent Publication No. 2-55154 discloses that a mold temperature at the start of pouring is measured, and a solenoid valve and a solenoid valve are determined based on a flow control card selected based on the level of the mold temperature at the start of pouring. A description is given of an apparatus which controls the supply amount of cooling water through a variable throttle.
[0006]
[Problems to be solved by the invention]
By the way, the method described in Japanese Patent Application Laid-Open No. 57-97838 controls the timing of stopping the supply of water without controlling the flow rate of the cooling water, so that it is difficult to finely control the mold temperature. There is.
[0007]
Further, those disclosed in Japanese Patent Publication No. 2-28416 and Japanese Patent Publication No. 2-55154 have a problem that it is difficult to perform a control that accurately grasps a change state of a mold temperature. That is, even if the mold temperature detected at the start of pouring is the same, the required cooling water flow rate is different between the case where the mold temperature rises sharply and the case where the mold temperature rises slowly. However, the above problem cannot be solved by control based only on the mold temperature at the start of pouring.
[0008]
The present invention has been made in view of the above circumstances, and has as its object to provide a mold temperature control device capable of accurately controlling the mold temperature of a casting mold.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 includes a temperature detecting unit that detects a mold temperature of a casting mold, and a cooling unit that cools the mold based on the detected mold temperature. Control means for controlling the flow rate of the cooling water, the control means calculates a time change rate of the mold temperature based on the detected mold temperature, The flow rate of the cooling water is feed-forward controlled from the start of pouring according to a future mold temperature predicted based on the temperature.
[0010]
According to the above configuration, the future change tendency of the mold temperature can be predicted based on the detected time change rate of the mold temperature. Therefore, the feedforward control for increasing or decreasing the flow rate of the cooling water based on the prediction is performed. Is performed from the start of pouring , whereby the mold temperature can be stabilized in a desired range.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0012]
1 to 5 show an embodiment of the present invention. FIG. 1 is a diagram showing a split surface of a fixed die, FIG. 2 is a diagram showing a split surface of a movable die, and FIG. FIG. 4 is a graph showing a change in mold temperature from the start of operation, and FIG. 5 is a graph showing a change in mold temperature and a change in cooling water flow rate during one cycle.
[0013]
1 of the die for casting a cylinder block of an engine, showing a split surface of the fixed die D _1. The fixed mold D ₁ has a cavity surface 1 for molding a cylinder block, four guide pins 2 for guiding the movement of a movable mold D ₂ described later, and a pouring port for pouring the cavity surface 1. 3 is provided.
[0014]
Figure 2 shows a split surface of the movable die D ₂ is coupled to the stationary die D _1. The movable mold D ₂ includes a central core 4 slidably guided by guide pins 2 extending from the fixed mold D _1, and a top core 6 forming a cavity surface 5 in cooperation with the central core 4. A ground core 7, a left core 8, and a right core 9 are provided. The top core 6, the ground core 7, the left core 8, and the right core 9 are movable with respect to the central core 4 by cylinders 10 to 13, respectively.
[0015]
The stationary mold D ₁ includes two temperature sensors S ₁ for measuring the mold _temperature, S ₁ is provided (see FIG. 1). Also the movable die D ₂ has its top side core 6, the ground-side core 7, the left core 8, the right core 9 and the temperature sensor S ₂ to S ₆ 5 pieces of the mold temperature measuring respectively the central core 4 (See FIG. 2).
[0016]
As shown in FIG. 3, the top core 6, the ground core 7, the left core 8, the right core 9, and the center core 4 (the left core 8, the right core 9, and the center) of the fixed mold D _{1 and the} movable mold D _2. Cooling water is supplied to the core 4 from a cooling water supply source 16 via a cooling water supply pipe 17..., And the cooled cooling water is discharged via a cooling water discharge pipe 18. . Each cooling water supply pipe 17 is provided with a flow meter 19 for detecting the flow rate of the cooling water and a flow control valve 20 for controlling the flow rate of the cooling water in series.
[0017]
Controller 21 composed of a microcomputer, controls the flow rate of the cooling water based on the detected mold temperature at each temperature sensor S ₁ to S _6. That is, the mold temperature detected as a resistance value by the temperature sensors S _{1 to} S ₆ is converted into a current value by the converters 22 and input to the control device 21, and the control device 21 performs cooling based on the mold temperature. A target value of the flow rate of water is set, and the opening of the flow control valves 20 is controlled so that the flow rate of the cooling water detected by the flow meters 19 matches the target value. The change in the flow rate of the cooling water is recorded on a recorder 23 connected to the control device 21.
[0018]
Incidentally, the top side core 6, the land side core 7 of the stationary mold D ₁ and the movable die D _2, the left core 8, the flow control of the cooling water for the right core 9 and the central core 4 are each independently and substantially since executed based on the same program, it will be described below the flow control of the cooling water with respect to the fixed die D ₁ as a representative.
[0019]
FIG. 4 shows a process in which the temperature of the mold, which has dropped to room temperature due to the stoppage of operation on a holiday, for example, rises due to restart of operation. Here, one chevron waveform corresponds to one cycle of casting (pouring → curing → product removal and release agent application → mold clamping). In the first region (1), in order to raise the mold temperature from room temperature to an appropriate temperature, casting is performed for 5 to 6 cycles with the supply of cooling water stopped. In this case, since the mold temperature has not risen to an appropriate temperature, the running of the hot water is insufficient and the quality of the product is poor, so that the product is dissolved and reused.
[0020]
In the region (2) where the casting of the subsequent 15 to 20 cycles is performed, the variation of the mold temperature falls within the castable range a, so that the product is temporarily good, and the variation of the mold temperature is narrower than the castable range a. In the region (3) falling within the ideal range b, more stable casting is possible. Then, in the regions (2) and (3), the flow rate control of the cooling water according to the present invention is performed.
[0021]
As shown in FIG. 5, one cycle A of casting includes a pouring step A ₁ , a curing step A ₂ , a product removal and release agent applying step A ₃ , and a mold clamping step A _4. hot mold temperature by injecting in step a ₁ melt rapidly increases, the mold temperature is lowered slowly by cooling the curing process a _2. The mold temperature by the product take-out and the releasing agent applying step A ₃ in parting by heat dissipation effect and a release agent applied by the cooling effect decreases rapidly, the reduction of the heat dissipation effect by the mold clamping step A ₄ in clamping Due to the transfer of the residual heat from the high-temperature portion, the mold temperature gradually decreases.
[0022]
In each of the steps A _{1 to} A ₄ , the mold temperature T of the fixed mold D ₁ continuously detected by the temperature sensors S ₁ and S ₁ is input to the control device 21, and the control device 21 transmits the mold temperature T The mold temperature change rate dT / dt is calculated every second as a deviation dT of the predetermined time dt (1 second in the embodiment). The mold temperature change rate dT / dt corresponds to the tangent (tan θ) of the inclination angle θ of the change curve of the mold temperature T.
[0023]
The controller 21 provides the optimum opening of the flow control valves 20... Corresponding to the respective mold temperatures T such that the opening of the flow control valves 20... When the mold temperature T is 300 ° C. is 50%. The degrees are stored in advance as a table. Therefore, when the mold temperature change rate dT / dt is calculated every second, the mold temperature T one second after the calculation time is predicted based on the mold temperature change rate dT / dt. Can be. That is, if the mold temperature at a certain moment is T ₁ and the mold temperature change rate is dT ₁ / dt, the mold temperature one second after that is predicted to be T ₁ + dT ₁ . The control device 21 searches the table for the target opening of the flow control valves 20 based on T ₁ + dT ₁ based on the predicted mold temperature one second later, so that the target opening can be obtained. Are feed-forward controlled.
[0024]
Thus, when the mold temperature T is increasing, the flow control valves 20 are opened with good responsiveness to increase the flow rate Q of the cooling water, and when the mold temperature T is decreasing, the flow control valves 20 are adjusted. As the cooling water flow rate Q is reduced with a good response, the mold temperature T falls within the ideal range b in FIG. 4 and stable casting becomes possible.
[0025]
Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made.
[0026]
For example, in the embodiment, the calculation of the mold temperature change rate dT / dt and the prediction of the mold temperature T are performed every second, but the time intervals can be changed as appropriate.
[0027]
【The invention's effect】
As described above, according to the invention described in claim 1, a future change tendency of the mold temperature can be predicted based on the detected time change rate of the mold temperature. By performing feedforward control for increasing or decreasing the flow rate of the cooling water from the start of pouring , the mold temperature can be stabilized in a desired range.
[Brief description of the drawings]
FIG. 1 is a diagram showing a split surface of a fixed mold. FIG. 2 is a diagram showing a split surface of a movable mold. FIG. 3 is an entire configuration diagram of a mold temperature control device. FIG. 4 is a mold temperature from the start. FIG. 5 is a graph showing a change in mold temperature and a change in cooling water flow rate during one cycle.
dT / dt Mold temperature time change rate D ₁ Fixed mold (mold)
D ₂ movable mold (mold)
Q Flow rate of cooling water S _{1 to} S ₆ Temperature sensor (temperature detecting means)
T Mold temperature 21 Controller (control means)

Claims (1)

Casting mold (D _1, D ₂₎ of the mold temperature detecting means for detecting the temperature (T) and (S ₁ ~S _6), it detected the mold based on the mold temperature (T) (D ₁ , D ₂ ), the control means (21) for controlling the flow rate (Q) of the cooling water for cooling the mold.
The control means (21) calculates a time change rate (dT / dt) of the mold temperature (T) based on the detected mold temperature (T), and calculates the time change rate (dT / dt) based on the time change rate (dT / dt). A mold temperature control device characterized in that the flow rate (Q) of cooling water is feed-forward controlled from the start of pouring according to a predicted future mold temperature (T).

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