JPS63212029A - Metallic die for edging press - Google Patents

Abstract

PURPOSE:To obtain the die for edging press difficult to cause a thermal fatigue crack by composing the titled die so as to fit a liner to the die main body by using the constraining tool constraining its movement only in the thickness direction by providing the liner by covering the face coming into contact with the slab of the die main body. CONSTITUTION:In the die of the press device performing edging in a specific width by feeding a hot slag between a pair of dies which open and close periodically, a liner 10 is provided by covering the face 2 relative to the slab of the die main body 1. This liner 10 is composed so as to be fitted to the metal die main body 1 by the constraining tool 8 constraining only the slab contact face 11 side at the upper and lower ends in the longitudinal direction. The liner 10 can thus be subjected to thermal expansion and contraction freely along the slab face without constraining in the longitudinal and height directions. Consequently the die of long service life difficult to cause thermal fatigue crack can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a mold for a press apparatus' for continuous width reduction of a hot slab.

(Prior Art) Conventionally, an integral mold made of tool steel or the like is used as a width reduction press mold (hereinafter simply referred to as a mold).

In order to extend the service life (usable life) of the mold, a method has been proposed in which a heat-resistant material such as 13 Cr is built up on the surface of the mold, or it is used alternately in multiple pairs of molds. (Refer to Japanese Unexamined Patent Publication No. 55-86637) (Problem to be solved by the invention) In the width reduction process, the mold is repeatedly heated and cooled, and the resulting thermal stress causes heat to be applied to the mold surface. Fatigue cracks occur. The life of the mold is determined by the time it takes for this crack to occur and the speed at which the crack progresses.

As mentioned above, metal molding can be achieved by overlaying the surface of the mold with a material that does not easily cause thermal fatigue cracks even when subjected to repeated thermal stress, or by alternately using multiple pairs of molds to reduce thermal stress. It can greatly extend the life of the mold.

However, these conventional techniques do not prevent the occurrence of thermal stress itself between the mold surface, which is repeatedly heated and cooled, and the mold rear surface, which is maintained at a nearly constant temperature. When the mold is used, the mold surface finally cracks (
Cracks) occur.

The present invention aims to solve the problems of the prior art, prevent the occurrence of thermal fatigue cracks on the mold surface, and extend the life of the mold semi-permanently.

[Structure of the Invention] (Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems. In the mold of a press machine that is fed and rolled down to a predetermined width, a liner is provided to cover the surface of the mold body facing the slab, and only the slab contact surface side of the liner is restrained at the upper and lower ends of the liner in the longitudinal direction. This is a mold for a width reduction press, characterized in that the liner is attached to a mold body using a restraining device.

(Function) A liner is provided to cover the surface of the mold body that comes into contact with the slab, and this liner is attached to the mold body by a restraint that restrains its movement only in the thickness direction, and is attached to the mold body in the longitudinal and height directions. Since the liner is not constrained by
This prevents thermal stress from occurring in the liner due to the difference in expansion and contraction of the liner as it heats and cools.

(Example 1) A first embodiment of the present invention will be described with reference to FIG. 1.2.

1 is a mold body made of a heat-resistant material such as tool steel, and in the center of the longitudinal direction (slab advancing direction indicated by the arrow) of surface 2 of the mold body 1 facing the slab (not shown), there is a mold body parallel to the slab. A parallel part 3 is provided, and an entrance inclined part 4 and an exit inclined part 5 are provided in succession to the parallel part 3 on the slab entry and exit sides of the mold body 1, respectively.

A rectangular notch 6.6 is provided on the upper and lower surfaces in the height direction of the surface 2 of the mold body l facing the slab. Restraints 8, 8 each having an L-shaped cross section and having locking pieces 7 projecting in the direction are fixed with a large number of screws 9.9.

So as to cover the surface 2 of the Nio mold body l facing the slab,
A liner 10 is provided along this surface 2. This liner lO is the surface that presses the slab, that is, the slab contact surface 11
Rectangular locking portions 12.12 are provided at the upper and lower ends of the rod over the entire length thereof.

The thickness Do of the central part of the liner 10 is equal to the thickness p of both sides thereof.
It is formed smaller than l. The thickness of the liner increases almost linearly to DI at the inclined portions 13 near both measuring portions, and the slab contact surface 11 of the liner IO is concave.

Note that Do is approximately 30■■, DI is approximately 40■■, liner height is approximately 310s■, and the portion where the thickness is small is approximately 70% of the liner height.

Then, the locking piece 7 protruding from the restraint tool 8 locks the liner 10.
The locking portions 12 of the liner 10 are engaged to restrain the liner lO from flying out from the mold body l, and the liner 10 is brought into close contact with the mold body l.

A gap g is formed between the upper end surface of the liner lO and the central side surface of the restraint tool 8. This gap g is liner l
The size of the thermal expansion of liner IO is the same as or larger than the thermal expansion allowance, and the movement in the longitudinal direction of liner IO is not restricted by restraint 8, so the thermal expansion and contraction of liner IO is not restricted in any way. Since the liner 10 can freely thermally expand and contract along the surface 2 of the mold body 1 facing the slab without being exposed to heat, thermal stress is not generated in the liner 10 and thermal fatigue cracks do not occur. .

In addition, the height d of the locking part 2 of the liner 10 is formed to be sufficiently larger than the gap g, and the liner 10 is curved in the longitudinal direction along the entrance side slope part 4 and the exit side slope part 5 of the mold body l. As a result, the liner 10 will not come off from the mold body l due to the impact force caused by the width reduction of the slab, and the liner lO
thermally expands and contracts freely along the slab contact surface 11 while tightly restrained by the restraint 8, but the temperature Ts of the surface of the liner 10 in contact with the slab is equal to the average temperature of the liner 10. Since it becomes larger than T11, as shown in FIG. 3, the liner IO is bent in the height direction and protrudes in an arc shape toward the slab side.

A force F shown by an arrow is applied to the liner 10 as the width of the slab is lowered, and the liner 10 is pressed against the mold body 1 when the width of the slab is lowered.
The material is forcibly pressed and bent back, generating bending stress, and this stress is repeatedly applied.

This bending stress Y (kg/mm2) is given by the following equation. (See Figure 6) Y=Eα(Ts - Tm) where E is Young's modulus (kg/mm"), α is the coefficient of thermal expansion, Ts is the liner surface temperature ("C), and Tm is the liner average temperature. .

As mentioned above, thermal fatigue cracks can be prevented from forming in the liner by restraining only the slab contact side of the liner, but if the above-mentioned unbending stress is repeatedly applied, the liner will become fatigued and the liner will crack. It has been found that this may occur and damage the liner.
In order to prevent the occurrence of cracks due to such superposition of working stress, the inventors of the present invention have repeatedly conducted numerous experiments using liners of various shapes, and have found that the liner can be The number of slabs that can be processed by (
The number of slabs processed) is the thickness of the center of the liner. heavily influenced by D.

It has been found that the occurrence of cracks can be prevented by setting the value to 80II11 or less.

FIG. 7 is a graph showing the relationship between the number of slabs processed and the liner thickness Do. It has been found that by setting the number of slabs to 80 ■ or less, the occurrence of cracks can be prevented and the number of slabs processed can be increased semi-permanently.

Note that similar results were obtained with the liners used in Examples 2 to 4 below. Furthermore, from the viewpoint of strength and machining, it is appropriate that the thickness of the liner be 15II11 or more.

(Example 2) A second example of the present invention will be described with reference to FIG. (Note that the sectional view is omitted because it is the same as FIG. 2.) In the second embodiment, a liner divided into a central liner 14, an inlet liner 15, and an outlet liner 16 is used. 17 and 18 are the entrance liner 1 to prevent the entrance liner 15 and the exit liner 16 from coming off the mold body l.
5. A screw for fixing the exit liner 16 to the mold body l. A gap G is formed between the entry liner 15, the exit liner 16, and the center liner, and the center liner 1
4 is configured to freely thermally expand and hang in the longitudinal direction without being restrained by the inlet liner 15 and the outlet liner. (The inlet liner 15 and the outlet liner 16 are only fixed at the ends near the central liner with screws 17 and 18, and the opposite ends are not fixed, so they can freely expand thermally in the longitudinal direction.) (This is clear.) Note that in Example 2, the gap G was set to 4.5 mm.

Since the other configurations are the same as those in the first embodiment, the same reference numerals are given to the drawings and the explanation will be omitted.

(Example 3.4) In place of the liner in Example 1.2, a liner of uniform thickness was used as shown in FIG. 5. Other configurations are in Example 1
．． It is the same as 2.

[Effect of the invention] The surface of the mold is covered with a liner that is separate from the mold body, and this liner can freely expand or contract thermally, so even if the mold is used for a long time, fatigue cracks will not occur. never occurs.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the first embodiment of the mold according to the present invention, Fig. 2 is a cross-sectional view taken along the line - Fig. 2, Fig. 3 is a cross-sectional view showing the deformed state of the liner during use, and Fig. 4 is A plan view similar to FIG. 1 of the second embodiment, and FIG. A cross-sectional view of the liner of the fourth embodiment,
FIG. 6 is a graph showing the relationship between liner thickness and unbending stress, and FIG. 7 is a graph showing the relationship between liner thickness and the number of slabs processed. In the figure, l is the mold body, 2 is the surface facing the slab, and 3 is the mold body.
4 is the parallel part, 4 is the entrance inclined part, 5 is the exit inclined part, 6 is the mounting part, 7 is the locking piece, 8 is the restraint, 9 is the screw, IO is the liner, 11 is the slab contact surface, 12 is the a locking part; 13 is an inclined part;
14 is a central liner, 15 is an inlet liner, 16 is an outlet liner, and 17 and 18 are screws. Figure 6: 1 bu floating

Claims (2)

[Claims] (1) In the mold of a press machine that intermittently feeds a hot slab between a pair of molds that are opened and closed periodically and reduces the width to a predetermined width, a liner is installed to cover the surface of the mold body facing the slab. A mold for width reduction press, characterized in that the liner is mounted on a mold body by a restraining device that restrains only the slab contacting surface side of the liner at the upper and lower ends of the liner in the longitudinal direction. (2) The width reduction press mold according to claim 1, wherein the liner has a thickness of 15 to 80 mm.