JPH0519171Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Field of Industrial Application) The present invention relates to a small diameter roll for electromagnetic stirring in continuous casting equipment. (Prior technology) In continuous steel casting equipment, in order to avoid the formation of dense segregation and pores inside the slab, electromagnetic induction stirring is applied to the slab that has unsolidified residual molten steel inside the solidified shell. Techniques for performing this are well known. For example, in Japanese Patent Application Laid-open No. 59-39454, a set of electromagnetic stirrers using a moving magnetic field installed in the upper support roll area of a large-section bloom continuous casting machine so as to sandwich the long side of the bloom in the slab drawing direction is disclosed. A pair of opposing stirring forces are generated in a horizontal cross section perpendicular to the molten steel to generate a rotational flow in the unsolidified molten steel of the slab,
An electromagnetic stirring device for a large-section bloom continuous casting machine is disclosed, which is configured with a pole pitch of 200 mm to 300 mm, and is characterized in that the frequency of magnetic field movement is a commercial frequency. As shown in FIG. 5, the electromagnetic stirring device in a continuous casting machine needs to be installed close to the slab 2 between the roll arrangements due to its functionality.
Small-diameter rolls 3 are arranged on both sides of the apparatus to ensure roll pitch, but the device indicated by the dotted line in the figure, including the electromagnetic stirring device 1 and the small-diameter rolls 3, is made of non-magnetic material. The purpose of using non-magnetic material in this part is: (1) To prevent the molten steel stirring thrust from decreasing due to disturbance of the magnetic flux density around the electromagnetic stirring device. (2) Suppress the temperature rise of the materials used due to the generation of heat and induced current in the electromagnetic stirring device itself. etc. For this reason, various improvements have been made to the small diameter rolls 3 installed on both sides of the electromagnetic stirring device 1, for example, the following are known. (1) A bush 8-A made of a non-magnetic material is provided on the inner circumference of the non-magnetic hollow roll 5 so that it can rotate between it and the shaft 6 (Fig. 3), and a bush 8-A that is replaced by (2) The non-magnetic solid roll 9 is rotationally supported by a bush 8-A made of a non-magnetic material (Fig. 4).
and one that is supported by a bearing made of non-magnetic material (see Figure 2). (Problems to be solved by the invention) Small-diameter rolls for continuous casting must withstand heavy loads despite restrictions on outer diameter dimensions due to the arrangement of surrounding equipment, and the necessity of using non-magnetic materials. There are the following problems. (1) Due to insufficient pressure receiving area of the bush,
Inconsistency in roll alignment due to bushing wear and an increase in the frequency of segment replacement due to roll failure, and furthermore, due to the use of copper alloy, the occurrence of scratches on the slab due to the bushing pieces biting into the slab. (2) Non-magnetic bearings Stainless steel is usually used, but the rated load is 1/1 compared to normal bearing steel.
The lining cost increases due to increased segment replacement frequency due to misalignment of roll alignment due to bearing wear, and increased production costs. (Means for Solving the Problems) The present invention has been made to advantageously solve the problems of the prior art, and includes: (1) a magnetic bearing is fitted on the inner periphery of a non-magnetic hollow roll; (2) A small-diameter roll for an electromagnetic stirring device, characterized in that the bearing of the non-magnetic solid roll is composed of a non-magnetic water-cooled outer shell and a magnetic bearing provided on the inner periphery of the non-magnetic solid roll. This is a small diameter roll for electromagnetic stirring equipment. (Function) Generally, when a magnetic material is placed within a magnetic flux, an induced current is generated and heat is generated. For this reason, when the electromagnetic stirring device is charged, a strong magnetic field is generated around it, so the small diameter roll located therein has been avoided from being made of magnetic material. However, what is used for small diameter rolls is
It is a non-(weakly) magnetic material such as SUS321, and a small amount of current flows through its surface layer. However, when considering the roll radial direction, the current flows only at the surface, and the depth is expressed as the depth δ from the skin.

[Formula] It can be expressed as: ω: Frequency σ: Electrical conductivity μ: Magnetic permeability. Therefore, as shown in FIGS. 1 and 2, even if a magnetic bearing 8-B is placed on the inner periphery of a hollow roll 5 whose surface layer is a non-(weakly) magnetic material, (Weak) Even if a magnetic bearing 8-B is placed inside a magnetic outer shell 7, no current will flow inside due to the skin effect (a small amount of current flows only in the surface layer). , the adverse effect of temperature rise on the bearing 8-B, the shaft 6, or the solid roll 9 is very small. (Effects of the invention) As described above, the invention has made it possible to use bearings made of magnetic material in small-diameter electromagnetic stirring rolls, thereby extending their service life and reducing the negative impact on slab quality. Remarkable effects such as being able to eliminate the problem can be obtained.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a sectional view showing another embodiment of the invention, Figs. 3 and 4 are sectional views showing a conventional small diameter roll, and Fig. 5 FIG. 2 is a side view showing an electromagnetic stirring device and a small diameter roll. 1... Electromagnetic stirring device, 2... Slab, 3... Small diameter roll, 4... Large diameter roll, 5... Hollow roll,
6...shaft, 7...outer shell, 8-A...butsu, 8
-B...Bearing, 9...Solid roll.

Claims (1)

[Claims for Utility Model Registration] (1) A small diameter roll for an electromagnetic stirring device, characterized in that a magnetic bearing is fitted to the inner periphery of a non-magnetic hollow roll. (2) A small diameter roll for an electromagnetic stirring device, characterized in that the bearing of the nonmagnetic solid roll is composed of a nonmagnetic water-cooled outer shell and a magnetic bearing provided on the inner circumference thereof.