JPH0763727B2 - Buckling prevention method for width reduction press - Google Patents

Description

TECHNICAL FIELD The present invention relates to a buckling prevention method when a material is subjected to width reduction by a width reduction press.

[Prior Art] It has been researched to perform a width reduction of a material such as a slab by a press capable of obtaining a large width reduction amount. Thus, when the width reduction by pressing is performed, the material buckles when the width reduction amount increases. In order to prevent this buckling, it is necessary to press the front and back surfaces of the material with a pressing roll to perform width reduction.

[Problems to be Solved by the Invention] However, even if the width is reduced by pressing with a press roll,
If the pressing force of the pressing roll is too large, dent deformation due to the pressing roll occurs on the upper and lower surfaces of the slab when the width reduction amount is large.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to prevent buckling deformation from occurring due to the pressing roll during width reduction over the entire length of the material and to effectively prevent buckling.

[Means for Solving the Problems] In the present invention, when both sides of a material are pressed by a pair of upper and lower presser rolls and the material is width-reduced by a width reduction press die, the pair of upper and lower presser rolls are respectively width-reduced. About 10 of power
It sets a force of less than or equal to%.

[Function] The material is pressed down by the pressing roll with a force of about 10% or less of the width reduction force, and the width is reduced by the pair of upper and lower pressing rolls, and the width is reduced by about 10% or less of the width reduction force, respectively. Since the material is pressed, the material is prevented from buckling and surface dents.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an outline of an apparatus used in the present invention. In the figure, 1 is a housing, 2a and 2b are opposed to each other by pressing cylinders 3a and 3b, and a pair of left and right dies for width-reducing a material 4 such as a slab. ,
Material 5 and 6 hold the center of the material 4 in the width direction from above and below
It is a pair of upper and lower presser rolls for preventing the buckling of the. The set force Pα for pressing the material of the press rolls 5 and 6 is Pα≈0.1Pw, where Pw is the width reduction force of the molds 2a and 2b.

When the material 4 is thickened in the vertical direction by performing the width reduction by the molds 2a and 2b, when the force above the set force Pα acts on the upper and lower pressing rolls 5 and 6 due to the thickness increase, the pressing rolls 5 and 6 are Material 4
Since the material 4 is pushed upwards or downwards, the material 4 is not dented by the pressing rolls 5 and 6, and the slab is not buckled during width reduction.

Next, set the force Pα of the presser rolls 5 and 6 by 10% of the width reduction force Pw.
The reason for the degree will be described based on the data obtained by the hot steel model experiment.

The agent 4 having the original slab width W is subjected to width reduction by keeping the width reduction force Pw and the width reduction amount ΔW constant and changing the set force P of the presser rolls 5 and 6 to P ₁ , P ₂ , P ₃ ... Buckling amount of material tip at that time a
(See FIG. 2) was measured. When this is shown in the graph,
As shown in FIG. 4, the material tip buckling amount a is large when the set force P when pressing by the presser rolls 5 and 6 is small, but the material tip buckling amount a becomes small when the set force P is large. I understand. If the maximum allowable buckling amount of the material tip is a _e , buckling of the material tip is acceptable if the setting force of the presser rolls 5 and 6 is larger than Pα, but buckling of the material tip is acceptable if it is smaller than Pα. I know what I can't do.

Next, for the material 4 having the original slab width W, the width reduction force Pw and the width reduction amount ΔW are kept constant, and the set forces P of the presser rolls 5 and 6 are set to P ₁ and P.
₂ , P ₃ ... was changed to perform width reduction, and the surface depression amount b (see FIG. 3) of the material at that time was measured. This is shown in the graph in Fig. 5. When the set force P when pressing with the presser rolls 5 and 6 is small, the surface dent amount b of the material is small, but when the set force P is large, the surface dent amount is large. b
Turns out to be bigger. The maximum allowable dent depth of the material
When b _e, surface indentation amount when the setting force Pα is found to be smaller than the allowable maximum dent amount b _e.

Therefore, from the graphs of FIGS. 4 and 5, when the material is subjected to the width reduction, the original slab width W, the width reduction force Pw, and the width reduction amount Δ
When the width is reduced by W, if the setting force Pα of the pressing rolls 5 and 6 is set, the material will not have unacceptable buckling or surface dents. Thus, the ratio of Pα and Pw is the result of various experiments. Met. Therefore, the setting force Pα of the presser rolls 5 and 6 may be 10% or less of the width reduction force Pw.

FIG. 6 shows the results of measuring the plate thickness distribution after the width press when the pressing roll setting force of the hot steel was changed. Board width 40
0 mm, width reduction 88 mm, presser roll width 100 mm, press temperature
Experiments were conducted at 1100 ° C. Presser roll force is 10% of width reduction force
In the case of No. 2, as shown by the curve A, a smooth plate thickness distribution with convexes on both ends is shown, and in particular, no dent deformation due to the press roll has occurred. On the other hand, when the width reduction force is 30%, as shown by the curve B, a dent deformation amount occurs in the central portion.

It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the buckling prevention method for a width reduction press of the present invention, it is possible to reliably prevent the buckling of the tip of the material, and the thickening of the material causes a force greater than the set force to act on the pair of upper and lower presser rolls. Then, the pair of upper and lower presser rolls are pushed or raised or lowered by the increase in the thickness of the material, so that it is possible to prevent surface dents due to the presser rolls, and therefore, various excellent effects such as good product quality can be obtained. Can play.

[Brief description of drawings]

FIG. 1 is an explanatory view of an apparatus used in the method of the present invention, FIG. 2 is an explanatory view of buckling caused by width reduction, FIG. 3 is an illustration of surface dent caused by width reduction, and FIG. 4 is a presser roll. Fig. 5 is a graph showing the relationship between the set force and the amount of buckling of the material tip, Fig. 5 is a graph showing the relationship between the press roll setting force and the amount of material surface indentation, and Fig. 6 is the case where the press roll setting force by hot steel is changed. 3 is a graph showing the results of measuring the plate thickness distribution after the width pressing. In the figure, 2a and 2b are molds, 3a and 3b are reduction cylinders, 4 is material, 5,
6 indicates a presser roll.

Claims (1)

[Claims] 1. When both sides of a material are pressed by a pair of upper and lower press rolls and the width of the material is reduced by a width reduction press die, the pair of upper and lower press rolls each have a width reduction force of about 1 mm.
A buckling prevention method for a width reduction press, which is characterized by setting a force of 10% or less.