JPS6362310B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for controlling pouring into a ladle. In particular, the present invention relates to a method for automatically controlling the tilting of a ladle by turning on and off a tilting actuator.

[Conventional technology and problems]

When pouring castings, it is desirable to pour the molten metal gently and at a constant rate. Particularly when a roll is made by centrifugal casting, where an outer shell is first formed and then a second molten metal is poured into it, it is necessary to pour the second molten metal as gently as possible. This is because if the flow of the molten metal to be cast is disturbed, the boundary with the outer shell will be disturbed and the quality of the roll will deteriorate.

Traditionally, pouring has been done using a ladle,
Typically, a ladle has a structure in which a spout is formed at the upper edge. In such a top pouring ladle, the pouring speed is controlled by changing the angle of inclination of the ladle.

However, it is extremely difficult to accurately control the pouring speed by changing the angle of inclination of a ladle containing a large amount of molten metal, and the reality is that this method relies on the empirical intuition of skilled workers. It is. In this method, the flow rate of the molten metal must be adjusted while visually measuring it, so it is extremely difficult to maintain it at a desired level at all times.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method of maintaining the pouring rate faithfully to a desired set level by automatically controlling the tilting of the ladle.

[Means for solving problems]

As a result of intensive research in view of the above problems, the present inventor discovered that there is a certain amount of delay (time difference) between the tilting of the ladle and the start of change in the molten metal flow rate, and that due to this, the flow rate can be adjusted to a predetermined level by tilting the ladle. Although it is difficult to maintain the delay, it has been discovered that the above object can be achieved by a control method that takes such a delay into account.

Based on this discovery, the automatic ladle pouring control method of the present invention is based on the following: △T is the time difference until the tilting operation of the ladle appears as a change in the velocity of the molten metal flow rate, and △T is calculated from the pouring speed at a certain point in time. Obtain the predicted value of the subsequent casting weight, compare the predicted value with the weight set value after △T based on the setting pattern, and if the set value is larger than the predicted value, turn on the tilting actuator of the ladle, otherwise If so, the operation of turning it off is repeated, and the casting speed is then controlled according to the set pattern.

[Effect]

The principle of the present invention will be explained with reference to FIGS. 1 and 4. First, the control method shown in FIG. 4 will be shown as a comparative example.
It is assumed that the curve A indicating the weight of poured metal differs from the straight line B indicating the set pattern by Δw ₁ at time t ₁ . Even if the ladle is tilted so as to immediately reduce this difference Δw ₁ to 0, the flow rate of the molten metal does not immediately increase. Due to this delay, the pouring amount still remains lower than the set pattern B by Δw ₂ at time t ₂ . Therefore, the ladle will continue to tilt. However, since there is a certain delay in increasing the pouring speed relative to the tilting of the ladle, the pouring speed remains high even if the pouring amount matches the set pattern, and the actual pouring amount exceeds the set pattern. (e.g. t ₃ ). Even if the tilting movement is stopped or reversed in this state, the drop in casting speed will be delayed, and the set pattern will be exceeded again, and this time it will become too small. Such fluctuations are repeated, and casting is performed in a state like curve C, which fluctuates greatly near the set pattern. This is not a satisfactory pouring pattern.

In contrast, FIG. 1 shows the pouring pattern of the present invention. First, the casting speed at t ₂ is determined from the increase Δw in the pouring amount in the minute time Δt between times t ₁ and t ₂ , and the predicted value C after the time difference ΔT is determined using the casting speed. If this predicted value C is smaller than the set value D of the set pattern B as shown in the figure, the ladle is tilted. This is because fluctuations in the casting speed appear after ΔT. When the ladle is tilted while performing such control at minute intervals of time Δt such as t ₃ , t ₄ , etc., the actual pouring pattern A slowly approaches the set pattern, and once it matches, it changes to the fourth pattern. It follows the set pattern very faithfully without causing large fluctuations as shown in the figure.

〔Example〕

The present invention will be explained in further detail by the following examples.

FIG. 2 shows an example of an apparatus for carrying out the method of the invention. The ladle 1 is provided with an electric motor 2, and a support member 3 fixed to the shaft of the electric motor 2 is hung on a hook 5 of a telemeter-type measuring instrument 4. Moreover, the measuring instrument 4 is suspended by a suitable hook. A casting mold 4 is arranged at a pouring position below the ladle 1. Furthermore, the electric motor 2 is connected to a suitable microcomputer device 7 via a cable 6. The measuring instrument 4 and the microcomputer device 7 each have an antenna 8,
9 is provided.

FIG. 3 is a flowchart illustrating the method of the present invention. Data of a setting pattern is input into the microcomputer device 7 in advance. After the start of casting, the weight of the entire ladle is measured by the scale 4 and transmitted to the microcomputer device 7 (A). By subtracting the weight of the ladle device itself using the microcomputer device 7, the amount of casting is determined. Alternatively, the signal from the measuring device 4 itself may be adjusted to represent the casting amount. As shown in FIG. 1, the pouring speed at time t ₂ is determined from the change Δw in the pouring amount during the minute time Δt between times t ₁ and t ₂ (B). In one preferred embodiment, Δt is less than a fraction of ΔT.

The time difference ΔT from when the ladle 1 is tilted until the pouring amount increases varies depending on the size of the ladle, but in one example is about 3 to 4 seconds. Since the pouring speed during △T is almost constant, the pouring amount after △T is △T
can be found by linear extrapolation. The value is set as the predicted value (C). Next, the predicted value and the set value according to the setting pattern are compared (D). If the predicted value is larger, the ladle tilting is turned off, and if it is smaller, it is turned on (E, F). Furthermore, the casting speed is determined at time _t3 after △t, and then △T
The tilting of the ladle is controlled by determining the later predicted value and comparing it with the set value. Do not perform operations like this in the future.
As the amount of pouring is increased every t, the pouring amount gradually approaches the set pattern, and after matching the set pattern, it does not greatly exceed it. In this respect, the control pattern is significantly different from the control pattern shown in FIG.

In the method of the present invention, when the predicted value is larger than the set value, the tilting of the ladle is turned off, that is, the tilting of the ladle is left as it is, and the ladle is not rotated in the reverse direction. I think that rotating the ladle in the opposite direction would speed up the control, but it has the disadvantage that the range of variation in the pouring amount becomes wider. Therefore, the operation of turning off the tilting of the ladle is important in obtaining stable control.

〔Effect of the invention〕

The automatic pouring control method of the present invention takes into account the time difference △T until the ladle tilting action appears as a change in the velocity of the molten metal flow rate, and calculates the difference between the predicted value of the pouring amount after △T and the set value. Since the tilting of the ladle is turned on and off by comparison, the pouring amount pattern can be made very close to the set pattern. In particular, since the tilting of the ladle is controlled on and off, the pouring amount pattern is extremely stable.

[Brief explanation of drawings]

FIG. 1 is a graph showing the control method of the present invention, FIG. 2 is a diagram showing an example of an apparatus for carrying out the method of the present invention, and FIG. 3 is a flowchart of the control method of the present invention. 4 is a graph showing a control method of a comparative example.

Claims (1)

[Claims] 1. A method for controlling the casting speed according to a set pattern by automatically controlling the tilting of a ladle having a tilting actuator, wherein the tilting operation of the ladle causes a change in the velocity of the flow rate of the molten metal. Let △T be the time difference until it appears, and △
A predicted value of the casting weight after T is obtained, and the predicted value is compared with a weight set value after △T, and if the set value is larger than the predicted value, the tilting actuator is turned on; otherwise, it is turned off. An automatic ladle pouring control method characterized by repeating the following operations. 2. The method according to claim 1, wherein the casting speed is determined from changes in ladle weight at the beginning and end of a minute time Δt that is sufficiently smaller than the time difference ΔT. automatic pouring control method. 3. The automatic ladle pouring control method according to claim 2, wherein the tilting actuator is turned on and off at every minute time Δt.