JPS60131928A - Prevention of strain at bottom end of coil in batch-wise annealing furnace - Google Patents

Abstract

PURPOSE:To prevent generation of strain in a coil by the effect of annealing by forming a slope of an upgrade from the inside and outside atop a coil receiving base and placing the coil wound in a way as to have the inclination meeting the slope on said base. CONSTITUTION:A coil receiving base 6' is placed on the cylindrical supporting base 4 in an inner case 1 and a slope 8 of an upgrade from the inside toward the outside is formed atop said base. The angle of inclination of the slope 8 is preferably about 1/100. A coil 7' which is wound to have the inclination so as to contact smoothly with the slope 8 is placed on said receiving base and is heated by a heater 9, then a gaseous atmosphere is supplied into the case through a supply pipe 10 to anneal the coil. Even if a difference in thermal expansion arises between the coil 7' and the base 6' on account of the above-mentioned annealing, the coil 7' is kept free from forced deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing distortion of the lower end of a coil in a hatch type annealing furnace.

Conventionally, annealing furnaces are used to improve the mechanical properties of steel and improve workability, and as a pedestal for supporting cylindrical thin plate coils, for example, as shown in Japanese Utility Model Application No. 57-87053, A circular plate with a flat top surface is well known.

However, in this type of coil holder, when the cylindrical thin plate coil is supported with its center axis vertically and annealed at a predetermined temperature, the coil holder 6 curves as shown in FIG.
It also deforms along the upper surface of the pedestal 6.

On the other hand, coil holders require high-temperature strength, so for example, S
High-grade stainless steel such as O3310S (25Cr 2ONi) 0) is used, and generally has a larger coefficient of thermal expansion than the materials to be annealed, such as ordinary steel and silicon steel, and its value is 12 × 10-'/°c for ordinary steel and silicon steel. ,5US310
S is about 1.5 times different from 18 x 10-bit C. Therefore, when the coil pedestal is deformed at height 714, the outer periphery of the lower end of the coil is forced to deform due to the thermal expansion difference with the coil due to the coil pedestal, causing distortion, and ultimately leaving a defective part that must be removed. This causes inconveniences that cause a decrease in yield.

That is, the yunni coil 7. shown in the strain generation mechanism explanatory diagram of FIG. Both coil pedestals 6 are horizontal, and due to the difference in thermal expansion coefficient between the coil and the coil pedestal, there is a difference in the amount of thermal expansion in the horizontal outer radial direction, and the coil pedestal moves toward the outer diameter of the coil by that difference. This will cause distortion.

The present invention has been made in view of the above-mentioned circumstances, and its gist is that in a batch type annealing furnace, an inclined surface rising from the inside to the outside is formed on the upper surface of the coil holder. The point is that by placing the wound coil on top of this at an angle of about 1 to match the slope of the pedestal, the coil will not be distorted even if there is a difference in thermal expansion between the coil pedestal and the coil. It is in.

This will be explained in detail below based on the drawings.

That is, FIG. 3 shows one embodiment of the present invention, in which a cylindrical inner case 1 is shown which covers the coil in the furnace and contains a protective atmosphere gas to prevent oxidation of the ζ steel.

The lower end of this inner case I is placed on the seal sand within a3 of the base 2.

A cylindrical support 4 having a predetermined height is fixed to the upper surface of the base 2, and a predetermined number of ventilation plates 5 are bored in the side wall of the support 4.

In the figure, 6' is a coil holder embodying the present invention, and an inclined surface 8 having an upward slope from the inside to the outside is formed on the upper surface of the holder. The bevel angle of the inclined surface 8 is preferably approximately 1/100, regardless of the size of the pedestal and the coil.

A coil 7° is placed on the coil holder 6'', which is wound at an angle so as to smoothly contact the inclined surface 8.The winding shape of the coil 7' is RPC (edge position control). This can be sufficiently controlled by using conventional techniques such as a device to gradually move a coil edge detector according to the thickness of the coil.

A plurality of heaters 9 are arranged on the base 2, and are heat sources for heating the coil 7'' to a predetermined temperature.

10 is a support stand 4. The coil 7 passes through the center of the coil holder 6゛.
The atmospheric gas supply pipe extends almost to the center of the
A protective atmosphere gas is supplied through this supply pipe 10.

However, by configuring the coil as described above, the strength of the coil becomes weaker toward the outer periphery. It becomes less susceptible to forced deformation due to expansion differences.

That is, as shown in the explanatory diagram of the distortion prevention mechanism in Fig. 4, the coil 7'' and the coil pedestal 6'' are tapered, and since the amount of thermal expansion of the coil pedestal 6'' is greater than that of the coil 7'', the coil 7'' is tapered due to thermal expansion. The taper of the pedestal 6" is the coil 7'
Since the taper is more horizontal, the closer to the outer diameter the coil 7
Since a gap A is created between the coil holder 6'' and the coil holder 6'', the outer circumferential portion of the coil 7'' is not subjected to any force that would cause strain due to tension.

Therefore, even if there is a difference in thermal expansion between the coil pedestal and the coil, the outer peripheral portion of the coil, which is most susceptible to the thermal expansion difference, is prevented from being forcibly deformed by the coil pedestal.

Incidentally, the effect of the strain prevention method of the present invention on yield reduction is obtained when the coil outer diameter is φ1500+aa to φ1800 mm.

In a coil weighing approximately 15 to 20 tons, the conventional method had a yield reduction of 5 to 2%, whereas the method of the present invention significantly improved the yield to 0.1 to 0.3%.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing how a conventional coil holder is used, Fig. 2 is an explanatory diagram of the strain generation mechanism, Fig. 3 is a sectional view showing an embodiment of the present invention, and Fig. 4 is a diagram showing the state of use of a conventional coil holder. FIG. 1... Inner case, 2... Base, 3... Groove. 4... Support stand, 5... Ventilation plate, 6.6'... Coil holder 7.7°... Coil, 8... Inclined surface, 9...
··heater. 10... Atmosphere gas supply pipe, A... Gap 27 wins back 2':j Sakae? , /7 Of course

Claims (1)

[Claims] In a batch type annealing furnace, a sloping surface rising from the inside to the outside is formed on the top surface of the coil pedestal, and the coil is wound onto this surface with an inclination that matches the slope of the pedestal. A method for preventing distortion of a lower end of a coil in a batch type annealing furnace, characterized in that the lower end of a coil is placed on the coil.