JPH06262342A - Automatic molten metal pouring control method - Google Patents

Abstract

PURPOSE:To provide an automatic molten metal pouring control method, in which a high quality cast product can be obtd., by controlling a head from a pouring hole of a ladle to the molten metal surface in the ladle. CONSTITUTION:At each prescribed time interval from starting of the molten metal pouring into a mold, the geometrical shape in the ladle according to a tilting angle of the ladle 1, the weight of the ladle containing the molten metal in the ladle 1 and the tilting angle of the ladle 1 are obtd. From these data, the head from the pouring hole of the ladle 1 to the molten metal surface in the ladle 1 is calculated. The tilting speed of the ladle 1 is controlled so that this head becomes the preset value at each time. Further, the height of the molten metal surface in a sprue cup is detected at each prescribed time interval. According to the difference between this detected height of the molten metal surface and the preset value, the setting value of the head at each time is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for automatically pouring molten metal into a mold.

[0002]

2. Description of the Related Art Various techniques have already been disclosed as control methods for automatically pouring molten metal into a mold. For example, in Japanese Patent Laid-Open No. 62-57758, the variation rate of the surface area of the molten metal in the ladle when the ladle is tilted in advance from the geometrical shape of the ladle is stored, and the variation rate is calculated according to the variation rate. A technique is disclosed in which the tilt angle of the ladle is changed to control the outflow amount of the molten metal from the ladle to a constant level. Japanese Patent Laid-Open No. 4-46665
The publication discloses a technique for controlling the tilting angle of the ladle by calculating the pouring speed from the measured value of the weight by means for measuring the total weight of the ladle including the molten metal.

[0003]

When pouring the molten metal into the mold, the pouring speed is set so that the molten metal from the ladle's spout is accurately poured into the spout cup. is doing. Therefore, the pouring speed is not proportional to the surface area of the molten metal in the ladle when the ladle is simply tilted. Therefore, it is not possible to control the pouring speed to be constant by paying attention to only the fluctuation of the surface area of the molten metal in the ladle. In the control method in which the weight of the molten metal in the ladle is fed back to the pouring speed, since the target is a liquid, a response delay occurs in the pouring speed even if the ladle is tilted. Further, in the vicinity of the start of pouring and the end of pouring, there is a difference in the control characteristics for the pouring speed from the ladle tilt angle, and the pouring speed cannot be controlled with good reproducibility.

Further, in the control method in which the pouring speed is fed back only from the total weight, it is only known that the same amount of molten metal is in the ladle, and if the tilting speed of the ladle at the time of measurement is different, The pouring speed fluctuates. When the pouring speed is calculated from the measured total weight, this total weight needs to be differentiated with respect to time, but there are problems such as time delay for calculation and easy noise.

Further, in order to obtain a high quality cast product,
It is necessary to keep the molten metal surface of the sprue cup of the mold constant. In order to keep the molten metal surface at the sprue cup at a constant height, it is necessary to control the pouring speed appropriately, but it is extremely difficult to find this control formula. Even if the same mold is used for automatic pouring with the same pouring speed pattern, the melt surface of the sprue cup does not always become constant. In the method that controls the tilt angle of the ladle by feeding back only the information of the molten metal surface of the sprue cup, phenomena such as undershoot or overshoot are likely to occur until a predetermined state is reached, resulting in instability. .

[0006]

According to the present invention, a geometric shape in a ladle according to a tilt angle of the ladle and a ladle containing the molten metal in the ladle are provided at predetermined time intervals from the start of pouring. The weight of the pot,
Calculate the tilt angle of the ladle, calculate the head from the tap opening of the ladle to the surface of the molten metal in the ladle from these data, and tilt the ladle so that the head reaches a preset value every time. It is an automatic pouring control method that controls the speed. Further, in the present invention, the height of the molten metal surface of the sprue cup is detected at predetermined time intervals, and the head for each of the times is detected according to the difference between the height of the molten metal surface of the sprue cup and a preset value. This is an automatic pouring control method in which the set value of is increased or decreased.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic view of an automatic pouring device for carrying out the present invention. In the figure, reference numeral 1 denotes a tiltable ladle which stores molten metal. 2 is a sprue cup provided in the mold. 3 is a servomotor for tilting the ladle 1, 4 is a ladle 1
A load cell for measuring the weight of the portion including the servo motor 3 and a control panel 6 for controlling the automatic pouring device, which includes a microcomputer or the like. 7 is a joystick for manually controlling the tilting angle of the ladle, 8 is a ladle 1
A hot water outlet sensor for detecting the hot water from the hot water, a hot water sensor 9 for detecting the hot water being poured from the ladle 1, and a hot spring cup sensor 19 for measuring the hot water surface of the hot spring cup 2.

FIG. 2 is a system configuration diagram of the apparatus shown in FIG. The CPU 11 in the control panel 6 controls the load cell 4, the values of the encoder 5 of the servomotor 3, and the joystick 7.
The tilt angle and the contents of communication with the sequencer 12 are fetched, and a command voltage is sent to the servo motor amplifier 13 based on those contents. The sequencer 12 receives the communication content from the tap sensor 8, the tap sensor 9, the cup sensor 19, and the CPU 11 and signals from the peripheral switches, and controls the automatic pouring device.

Next, the method of controlling the pouring speed will be described with reference to FIG.
Will be explained. In FIG. 3, 16 indicates a horizontal position from the tap opening of the ladle 1, and 17 indicates a molten metal surface position at the time of pouring. This distance becomes the head 15. When pouring the molten metal into the mold, the flow rate of the molten metal over the weir installed near the tap opening of the ladle 1 can be calculated as a polynomial of the square root of the head 15, as shown in JIS B8302. Q is the polynomial that represents the flow rate of the molten metal poured from the ladle 1.
= F (Y). Here, Q is the pouring speed. Time n
If the target pouring speed Qn at
The target head Hn + 1 is √H from the inverse function F ⁻¹ 1 of the function F.
_{It is calculated as n + 1} = F ⁻¹ (Q _n ). The method of obtaining F ⁻¹ is to set the target head √H _n at time n−1 as an initial value, and the polynomial solution can be obtained by the Newton method.

When the ladle 1 is filled with the molten metal at the lathe tilt angle θ, the total weight W is W = G (θ) from the geometrical shape of the ladle 1.
Express. Similarly, the molten metal surface area A in the ladle 1 at the ladle tilt angle θ is A = K (θ) due to the geometrical shape of the ladle. The total weight measured by the load cell 4 at time n is W
_{Let n be} the tilt angle measured by the encoder 5 be θ _rn and the target tilt angle at time n + 1 be θ _{n + 1} , then H _{n + 1} is the weight of the molten metal flowing out (W _n −G (θ _rn )) _Is divided by the melt surface area K (θ _rn ) and the melt density γ, so that (W _n −G (θ _rn )) / K (θ _rn ) / γ = H _{n + 1.}・ (1) There is a relationship. From this relationship, θ _{n + 1} = G ⁻¹ (W _n −K (θ _rn ) × H _{n + 1} × γ) ... (2) The target tilt angle θ _{n + 1} at time n + 1 is obtained. . Also And Therefore Sa - Vomo - Taanpu the command voltage V _n to send the _{13 V n = K p × (} θ n + 1 -θ rn) + K i × θ e ········· (4) to. Here, K _p and K _i are proportional constants. By the above method, the head 15 can be controlled to be the target head H _{n + 1} , and the pouring control can be performed. A flowchart of the above method is shown in FIG.

It is assumed that after several experiments, the total weight measured is differentiated with respect to time and the target Q _n is compared, and a response delay d occurs on the time axis. When running in practice, since it has been found the target pouring speed at a certain time, a target pouring speed of at a certain time n instead of the Q _n, corresponding to the Q n _{+ d} and the time delay d .

Further, the measured value L _n of the sprue cup sensor is set as
Assuming that the target measured value of the melt surface of the sprue cup is L, if the melt surface is lower than the measured value L of the melt surface of the target spout cup, the target head H _{n + 1} is increased, and if it is higher, the target head H _{n +.} Reduce _{1 H n + 1 = (W n} -G (θ rn)) / K (θ rn) / γ + K pp × (L-L n) ······ (5) K pp is a proportional constant. This makes it possible to control the head and make the melt surface of the sprue cup constant. In addition,
The above calculation is performed by the CPU 11 in the control panel 6.

[0013]

According to the method described above, the molten metal head 15 is
Therefore, it is possible to control the pouring speed with high accuracy, and it is possible to produce a higher quality cast product.

[Brief description of drawings]

FIG. 1 is a schematic view of an automatic pouring device showing an embodiment of the present invention.

FIG. 2 is a system configuration diagram of the apparatus shown in FIG.

FIG. 3 is a diagram for explaining a method for controlling a pouring speed.

FIG. 4 is a flowchart showing a control procedure of the present invention.

[Explanation of symbols]

 1 Ladle 3 Servo Motor 4 Load Cell 5 Encoder 8 Hot Spring Sensor 9 Hot Spring Sensor 11 CPU 13 Servo Motor Amplifier 15 Head 19 Hot Spring Cup Sensor

Claims (2)

[Claims] 1. At a predetermined time interval from the start of pouring,
With the geometric shape in the ladle according to the tilting angle of the ladle,
The weight of the ladle containing the molten metal in the ladle and the tilt angle of the ladle are obtained, and the head from the tap opening of the ladle to the surface of the molten metal in the ladle is calculated from these data. An automatic pouring control method, characterized in that the tilting speed of the ladle is controlled so as to reach a preset value for each time. 2. The height of the molten metal surface of the sprue cup is detected at predetermined time intervals, and the height of the molten metal surface of the sprue cup is adjusted according to a difference from a preset value. The automatic pouring control method according to claim 1, wherein the set value is increased or decreased.