JPS63215357A - Continuous casting method - Google Patents

Abstract

PURPOSE:To improve the quality of a casting product and the safety of casting operation by detecting molten surface position of molten metal in a tundish, automatically conversing the variation into the motion of a molten metal controlling rod and holding the molten surface level of a metal to the fixed position. CONSTITUTION:The molten metal controlling rod 3 is arranged in a melting furnace 1 and also a float 8 and a sensor 9 are arranged each in the tundish 4. When position of the float 8 in the tundish 4 (the molten surface level of the molten metal) is varied, an A/D converter 10 and a personal computer 11 operate the position variating value of the float 8 through the sensor 9, and drive a driving device 13 and a direct moving system 14, to drive the molten metal controlling rod 3 under variable speed control. In this way, as the molten surface level in the tundish 4 is always held to the fixed position, the variation of the molten metal head is extremely a little. Therefore, the quality of the casting product is improved and also the safety of the casting operation is remarkably improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for maintaining a constant liquid level of molten metal in a tundish during continuous casting, that is, the pressure (head) of molten metal applied to a mold during continuous casting. , relates to a method for continuously casting castings with high precision, stable quality, and performance while preventing breakouts.

[Conventional technology]

In the conventional continuous casting method, a molten metal control rod installed in a metal melting furnace (crucible), which melts and stores a predetermined amount of metal, is supported by a ball screw, etc., and this ball screw is controlled manually or by a gear motor, etc. A common method is to lower the molten metal control rod in the melting furnace at a speed of It is true.

In such continuous casting, the temperature of the mold, the amount and speed of extrusion of molten metal from the mold, the amount of cooling water, etc. are controlled in order to maintain a constant solidification interface of the cast product formed and drawn from the mold. Typically, the temperature of the mold is detected and the amount of cooling water is controlled based on that temperature, with other conditions kept constant.

However, in such continuous casting, there are limits to the control of the descending speed of the molten metal control rod in the melting furnace, that is, the amount of molten metal supplied into the tundish, by the drive or gear motor, etc. When casting a cast product, there are problems in that slight fluctuations in the amount of molten metal supplied make continuous casting impossible, and continuous casting becomes impossible with metals that easily break out, such as non-ferrous metals.

Even in normal continuous casting, slight fluctuations in the supply amount of the molten metal and fluctuations in the withdrawal speed of the cast material affect the quality and performance of the resulting product, so it is desirable to reduce them as much as possible. Furthermore, in this continuous casting, it is undesirable from the viewpoint of labor saving that the operator must constantly monitor the casting equipment in order to avoid pressure fluctuations of the molten metal in the tundish that can lead to breakouts. The inability to continuously change the casting speed was a disadvantage in producing a wide variety of cast products.

[Purpose of the invention]

The purpose of the present invention is to automatically control the liquid level of molten metal in the above-mentioned continuous casting to prevent fluctuations in the pressure of molten metal applied to the mold, and to improve the ability to respond in real time to continuous changes in casting speed. To provide a new casting method.

[Structure of the invention]

The object of the present invention is to lower a molten metal control rod provided in a metal melting furnace at a constant speed, supply the molten metal in the melting furnace into a tundish, and cast the metal through a mold provided in the tundish. In the method, the liquid level of the molten metal in the tundish is adjusted by sensing the liquid level position of the molten metal in the tundish and automatically converting fluctuations in this liquid level position into variable speed movement of a molten metal control rod. This can be achieved by holding constant.

That is, the present invention focuses on the fact that in order to solve various technical problems of continuous casting, such as breakouts, it is necessary to maintain a constant head of molten metal applied to the mold in the tundish. They discovered that by keeping the liquid level of the molten metal in the tundish constant, it is possible to keep the head applied to the mold constant, and arrived at the present invention.

Embodiments of the present invention will be specifically described below based on the drawings.

The figure is a flowchart diagram illustrating one aspect of the continuous casting method of the present invention. As shown in the figure, a predetermined amount of metal 2 melted in the melting furnace 1 is continuously supplied into the tundish 4 by lowering a molten metal control rod 3 provided in the melting furnace 1. The molten metal 2 in the tundish 4 is in the mold 5
The material is extruded while being molded through the material, cooled by a cooling device 6, and taken up by a group of pinch rollers 7.

A feature of the present invention is that in such a continuous casting method, the position of the molten metal liquid level in the tundish 4 is detected and the fluctuation of this liquid level position is automatically converted into variable speed movement of the molten metal control rod 3. Specifically, a float 8 is installed above the molten metal liquid level, the position of this float 8 is detected by a sensor 9, and when the position W of this float 8 (the liquid level of the molten metal) changes, the sensor 9 detects the position of the float 8. A/D converter 1 via 9
0 and the PC 11 calculate the fluctuation value of the position of the float 8 (the liquid level of the molten metal), and based on this, the control device 12) drives the drive device 13 such as a stepping motor or servo motor, and the linear motion system 14 (support column 15) to drive the molten metal control rod 3
By operating the tank at variable speed, the liquid level in the tundish is kept constant. That is, the position of the float 8 above the liquid level of the molten metal 2 in the tundish 4 is monitored by the sensor 9 during the entire casting process, and as soon as the position of the float 8 changes, the control device 1
2 moves, the melting control rod 3 is operated at variable speed, and the liquid level of the molten metal 2 in the tundish 4 is instantly adjusted (
The head that is added to the mold is returned to its original level.

〔Effect of the invention〕

According to the present invention, since the liquid level of the molten metal in the tundish, that is, the head applied to the mold can be kept constant, fluctuations in the head applied to the mold during continuous casting can be made extremely small, and substantially breakout can be prevented. Such stabilization of continuous casting improves the quality and performance of the cast product, significantly improves the safety and workability of casting, and makes it possible to save labor.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining the ILi aspect of the continuous casting method of the present invention. DESCRIPTION OF SYMBOLS 1... Melting furnace, 3... Molten metal control rod, 8... Float, 9... Sensor, 13... Drive device, 14 Direct motion system.

Claims (2)

[Claims] (1) A method in which a molten metal control rod provided in a metal melting furnace is lowered at a constant speed, molten metal in the melting furnace is supplied into a tundish, and the molten metal in the tundish is cast through a mold provided in the tundish. The liquid level of the molten metal in the tundish is maintained constant by detecting the liquid level position of the molten metal in the tundish and automatically converting fluctuations in the liquid level position into variable speed movement of the molten metal control rod. A continuous casting method characterized by: (2) In claim 1, the means for detecting the liquid level position of the molten metal in the tundish is a means for placing a float on the liquid level of the molten metal and detecting the position of the float with a sensor. A continuous casting method characterized by adopting.