JPS6147626B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for automatically pouring molten metal into a mold.

In order to pour molten metal into a mold without causing defects due to pouring, in principle, it is sufficient to pour the molten metal while always keeping the molten metal in a sump provided at the sprue of the mold.

However, since the molten metal swallowing speed usually differs between the initial and final stages of pouring, it is necessary to control the pouring speed during pouring in order to maintain the molten metal in the sump. Recently, automatic pouring methods have mainly been based on flogram setting pouring speed control, which electronically detects the molten metal level in the sump and feeds back this as a control target to maintain the molten metal level at a constant level. An additional automatic pouring method is used.

The conventional automatic pouring method described above is shown in Figures 1 to 4.
This will be explained based on the diagram.

FIG. 1 is a diagram showing a device for carrying out an automatic pouring method, and the device includes a mold sump 1, a ladle 2, a ladle tilting cylinder 3, and an electromagnetic device for controlling the ladle tilting cylinder 3. The control device 5 has a control circuit that determines a pouring speed pattern, and a detector 6 that detects the level of molten metal in the mold sump 1. As this detector 6, it is possible to use a two-dimensional sensor.

FIG. 2 employs a two-dimensional sensor as the detector 6 of FIG. 1, and shows an image of the state of the mold sump 1 formed within the field of view of the detector from directly above or diagonally above. In the figure, the image consists of a flow 7 of hot water from the ladle 2, a bright area 8 consisting of the molten metal, and a dark area 9 consisting of other areas, where a is the state immediately after the start of pouring, and b is the state immediately after the start of pouring. A state in which the pouring is controlled to maintain the standard level shown in FIG. 3 during pouring, and c shows a state in which the molten metal exceeds the standard level shown in FIG. 3 and fills the mold. The detection unit 6 can detect the hot water level by measuring changes in the size of the bright areas 8 or dark areas 9 of this image.

FIG. 3 is a diagram showing the molten metal level in the mold sump 1, and FIG. 4 is a diagram showing the pouring speed pattern of a certain type of mold and the corresponding ladle tilting speed pattern. In the figure, T ₀ is the time when the molten metal starts to be dispensed from the ladle 2, and the ladle 2 is tilted at a high speed V ₀ during the T ₀ period. After the start of tapping, the molten metal reaches the third stage.
During the period T ₁ until the reference level shown in the figure, that is, the target level to be maintained, is reached, the ladle 2 is tilted at medium tilting speeds V ₁ and V ₂ in order to quickly pour hot water into the mold. Control.

At point A shown in Fig. 4, the molten metal flows into the mold sump 1.
reach the standard level. During the period _T2 from when the molten metal reaches the standard level until the mold completes the cupping, it is divided into multiple time periods, e.g. _t1 to _t5 , and _V3
The ladle 2 is tilted at a tilting speed of ~V ₇ . _V3 ～ _V7
is an appropriate speed to keep the level of the hot water as constant as possible under normal pouring conditions, and is programmed in advance. Then, at point B shown in FIG. 4, the mold completes making the teacup and becomes full. During the period T ₃ after the mold has finished filling the ladle 2 with a tilting speed V ₈
Turn it in the opposite direction and drain the water. In this way, one cycle of pouring work is completed. The above-mentioned pouring speed control program is determined to match the teacup characteristics of the mold. However, during actual pouring work, there are various disturbance factors, and it is difficult to maintain the molten metal level in the mold sump 1 at a reference level. Therefore, for example, if the molten metal level in the mold sump ₁ reaches the upper limit level LOW shown in _FIG . let Normal t ₁ ~ _{t 4}
Since the ladle tilting speed during this period is low, the pouring speed does not decrease rapidly but slowly decreases, and the molten metal level smoothly returns to the reference level shown in FIG. 3. On the other hand, if the molten metal level in the mold sump 1 reaches a predetermined lower limit level during the period _t1 to _t4 , the tilting speed of the ladle 2 will be slightly reduced by the detection signal from the detection unit 6. The speed is increased and the molten metal level is smoothly returned to the reference level shown in FIG. When the molten metal level returns to the reference level, the ladle 2 begins to tilt again according to the tilting speed determined by the control program.

Moreover, during the period _t1 to _t4 , the molten metal level in the mold sump 1 reaches the overflow level shown in FIG.
When the detection signal from the detector 6 indicating this state is maintained for a certain period of time, it is determined that the mold is full, and the ladle 2 is reversely tilted to stop pouring.

Finally, if the molten metal level in the mold reservoir reaches the upper limit level LOW during period _t5 , and the detection signal from detector 6 indicating this state is maintained for a certain period of time, it is determined that the mold has completed filling. Ladle 2 at tilting speed V ₈
Reverse tilt to drain hot water.

The conventional automatic pouring method has been described in detail above, but this conventional automatic pouring method has the following drawbacks. That is, when the molten metal level reaches the upper limit level L during the pouring period, the tilting speed of the ladle 2 is reduced and the molten metal injection speed is corrected to decrease, but the mold is lower than the corrected molten metal injection speed. The molten metal swallowing speed may be slow. In such a case, the molten metal level rises and immediately reaches the overflow level, and even though the mold is not full of molten metal, it is misdiagnosed that the mold is full, and ladle 2 is reversed and pouring is stopped. It will end up being put away.
Furthermore, since there is a time lag due to mechanical operation delays and the like from when the detection unit 6 detects the overflow level until the ladle 2 actually starts to reverse, the mold swallowing speed of the molten metal is affected as described above. If this is very slow, there is a risk that the molten metal will overflow from the mold sump 1.

In order to solve the above-mentioned drawbacks, the present invention provides an automatic pouring method in which a setting level for reversing the ladle is provided in addition to the overflow level, and the amount of molten metal poured can quickly follow changes in the molten metal level. The purpose is to provide

Hereinafter, an embodiment of the automatic pouring method according to the present invention will be described based on the mold pouring speed pattern shown in FIG. 5 and the ladle tilting speed pattern corresponding thereto.

In the figure, T ₀ is the time when the molten metal starts to be dispensed from the ladle 2, and the ladle 2 is tilted at a high speed V ₀ during the T ₀ period. During the period T ₁ after the start of tapping until the molten metal reaches the reference level, the ladle 2 is tilted at medium speeds V ₁ and V ₂ to quickly pour hot water into the mold. At point A, the molten metal reaches the reference level of the mold sump 1.

During the period _T2 from when the molten metal reaches the standard level until the mold completes the potting process, the ladle 2 is tilted at a tilting speed of _V3 to _V7 , divided into a plurality of time periods.

V ₃ to _{V 7} are appropriate speeds to keep the molten metal level as constant as possible under normal pouring conditions, and are programmed in advance. Then, at point B, the mold completes filling the teacup and becomes full. During the period _T3 after the mold has finished filling the teacup, the ladle 2 is reversely tilted at a tilting speed _V9 to drain the hot water. In this way, one cycle of pouring work is completed. Next, if the molten metal level in the mold sump 1 reaches the upper limit level LOW during periods t ₁ , t ₂ , and t ₅ due to disturbance factors, the detection unit 6
On the other hand, if the molten metal level in the mold sump 1 reaches the lower limit level during the same period, the ladle tilting speed is decreased based on the detection signal from the detection unit 6. is slightly increased to maintain the molten metal level at the reference level. Also, during the same period, if the molten metal level in the mold reservoir 1 reaches the overflow level C and the detection signal from the detector 6 indicating this state is maintained for a certain period of time, the ladle 2 is tilted backwards and the molten metal is poured. to stop. If the molten metal level in the mold sump reaches the upper limit level LOW during period t ₆ and the detection signal from detector 6 indicating this state is maintained for a certain period of time, ladle 2 is reversely tilted at speed V ₉ . Have them drain the water.

The pouring control method described above is the same as the conventional method, but the present invention is such that the ladle 2 is temporarily reversed when the molten metal level reaches a predetermined set level during the pouring cycle. Has characteristics.

The setting level for reversing this ladle 2 is:
It may be the upper limit level L shown in FIG. 3 or a plurality of levels provided between the upper limit level L and the overflow level C. For example, when the molten metal level in the sump 1 reaches the upper limit level LOW during period _t3 (corresponding to point C in Fig. 5), the ladle 2 is rotated at a tilting speed of V ₈ based on the detection signal from the detection unit 6. and then rapidly reduce the pouring rate. This lowers the molten metal level. When the molten metal level reaches the reference level I after the period _t4 has elapsed, the ladle 2 is again rotated forward at a tilting speed _V6 and tilted according to the tilting speed determined by the control program.

As explained above, in the automatic pouring method of the present invention, the ladle is temporarily rapidly reversed to reduce the amount of molten metal poured, so the amount of molten metal poured can quickly follow changes in the molten metal level. This is an excellent method in that even if the mold swallows the molten metal at a slower speed than the molten metal injection speed, the pouring operation will not be stopped and the risk of molten metal overflowing from the sump can be prevented. It will be effective.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a device for carrying out the automatic pouring method, and Figure 2 is a diagram showing the state in which the level of molten metal in the mold sump is detected by the detector shown in Figure 1. Immediately after starting the melt, b shows the state in the middle of pouring, c shows the state filled with molten metal, Figure 3 shows the molten metal level in the mold sump of Figure 1, and Figure 4 shows the conventional automatic pouring method. FIG. 5 shows the mold pouring speed pattern and the corresponding ladle tilting speed pattern according to the automatic pouring method according to the present invention. FIG. 1; sump, 2; ladle, 5; control device, 6; detector.

Claims (1)

[Scope of Claims] 1. The molten metal is poured into the mold by monitoring the level of the molten metal in the mold sump with a detector, and the pouring time is divided into a plurality of time periods, and the ladle is tilted for each period. In the automatic pouring method that controls the speed, the ladle is reversed when the level of hot water in the mold sump reaches a predetermined level in each of the time periods. Hot water method. 2. The automatic pouring method according to claim 1, wherein the set level is an upper limit level higher than the reference level. 3. The automatic pouring method according to claim 1, wherein a plurality of setting levels are provided.