JPS61100636A - Method and apparatus for uniformly pulling metal material - Google Patents

Abstract

PURPOSE:To prevent breakage from a tensile force applied part or the vicinity thereof in a tension test, by providing temp. difference such that the temp. of the tensile force applied part of a metal material becomes lower than that of the part to be pulled thereof. CONSTITUTION:Both end parts of a pipe 1 are grasped by chucks 2a while the central part thereof is heated in a heating furnace 3 using a heater 3a and the chuck parts 2a are pulled to apply plastic deformation to the pipe 1. At this time, the end parts of the pipe 1 are lower than the central part thereof in temp. and strength becomes high toward the end parts corresponding to a temp. gradient. Therefore, no breakage is generated at the chuck parts 2 and the vicinities thereof and uniform pulling can be performed and dimensional correction such as the removal of bending, the adjustment of a wall thickness and the reduction in residual stress are enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method and apparatus for uniformly stretching metal materials suitable for uniformly stretching materials.

[Background of the invention]

Conventional tensioning devices reduce the cross-sectional area of the central part to prevent breakage near the chuck part, as seen in JIS standard tensile test pieces, such as No. 1 test piece. All I had to do was grab the end of it with a zipper. However, when a rod, plate, or tube having a constant cross-sectional area in the longitudinal direction is pulled, there is a drawback that the rod, plate, or tube cannot be pulled evenly because the rod, plate, or tube has a constant cross-sectional area in the longitudinal direction because the rod, plate, or tube breaks due to constriction near the chuck portion.

[Purpose of the invention]

An object of the present invention is to provide a method and apparatus for uniformly pulling a metal material having a constant cross-sectional shape while preventing breakage from the tensile force applying portion and its vicinity.

[Summary of the invention]

Generally, the strength of a metal material decreases as the temperature rises. According to the present invention, when the material is pulled uniformly without changing its cross-sectional area, the temperature of the part of the metal material to which the tension is applied is higher than that of the part to which the tensile force is applied. By adding such a temperature difference,
This is to prevent breakage from the tensile force application area and its vicinity.

['Embodiments of the invention]

Embodiments of the present invention will be described using FIGS. 1 to 4.

FIG. 1 is a diagram showing the relationship between yield stress and temperature of zirconium soba. As seen in this figure, in general, the higher the temperature of a metal material, the lower its deformation resistance. therefore,
The method and apparatus of the present invention take advantage of this property.

FIG. 2 is an explanatory diagram of a uniform tensioning device, in which both ends of the tube 1 are gripped by chucks 2a while the center portion of the tube 1 is heated in a heating furnace 3 using a heater 3a. Part 2 is stretched and plastically deformed. At this time, the temperature of the ends of the tube 1 is lower than that of the center, and the strength increases toward the ends according to the temperature gradient. Therefore, no breakage occurs in the chuck portion 2 or its vicinity. In this case, the material may be a rod or a plate. Further, although a heater is used as a heat source, other heating methods such as high frequency heating means and combustion heating means 2 may be used.

According to this embodiment, since the metal material is heated, the tensile load can be smaller than when it is cold, and the function of the tension device 2 can be reduced.

FIG. 3 shows another embodiment of the uniform tensioning device, in which a cooling pipe 4 is provided in the chuck part 2 to cool one end of the tube, and while cooling water or a cooling liquid such as helium is passed through it, the tube is 1 is stretched and plastically deformed. At this time, the temperature of the ends of the tube 1 is lower than that of the center, and the strength increases toward the ends according to the temperature gradient. Therefore, no breakage occurs in the chuck part 2 or its vicinity. In this case, the material may be a rod or a plate.
Although a cooling pipe was used as the cooling means, a hole may be made directly in the chuck portion and cooling water or a cooling liquid may be passed through the hole.

According to this embodiment, there is an effect that the metal material is stretched cold and plastically deformed.

FIG. 4 shows yet another embodiment of the uniform tensioning device, in which heated fluid such as oil heated using a heating means (not shown) is injected into the tube 1 through the inlet 5a and discharged through the outlet 5b. At the same time, while heating the tube 1, cooling water or cooling liquid is circulated through the cooling pipe 4 using a cooling means (not shown) to cool the chuck part 2 while pulling the tube 1 to plastically deform it. It is. At this time, the temperature at the ends of the tube is lower than that at the center, and the strength increases toward the ends according to the temperature gradient. Therefore, no breakage occurs in the chuck portion 2 or its vicinity. In this case, a cooling pipe was used as a cooling means, but a hole was made directly in the chuck part.
According to this embodiment, since the material is heated, the deformation resistance is smaller than when it is cold, so the device and its functions can be small.

In this embodiment, heating fluid was circulated through the tube as a heating means for the tube, but the tube 1 could be heated in the furnace by using a heating furnace that includes the entire device or a heating furnace that includes only the center portion of the tube. The tube 1 may be stretched and plastically deformed while heating and simultaneously cooling the tube end. In this case, the material may be a plate or a bar.

As described above, since the metal material can be stretched uniformly, it is possible to stretch the material to correct dimensions such as removing bends, adjust wall thickness, reduce residual stress, etc.

〔Effect of the invention〕

As explained above, according to the present invention, when pulling a metal material whose thickness and width are constant in the longitudinal direction, the material can be pulled uniformly without causing breakage near the chuck part. Dimensional correction such as removing bends by pulling, adjusting wall thickness, reducing residual stress, etc. are possible.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between yield stress and temperature of zirconium alloy, Fig. 2 is an explanatory diagram of a uniform tensioning device related to the present invention, and Fig. 3 is an explanatory diagram of another embodiment of the uniform tensioning device.
FIG. 4 is an explanatory diagram of still another embodiment of the uniform tensioning device. 1... Pipe, 2... Chuck part, 3... Heating furnace, 5
a...Heating fluid inlet, 5b...Heating fluid outlet,
4... Cooling 1 degree (2 recesses etc. ￥-3 diagram)

Claims (1)

[Scope of Claims] 1. By providing a temperature difference such that the temperature of the part of the metal material to which tensile force is applied is lower than that of the part to which tension is applied,
A method for uniformly stretching a metal material, which is characterized by increasing the strength of a part to which a tensile force is applied than a part to be stretched, thereby preventing breakage from the part to which tension is applied and its vicinity. 2. An apparatus for uniformly tensioning a metal material, characterized in that it is provided with means for applying a temperature difference such that the temperature of the part of the metal material to which a tensile force is applied is lower than that of the part to be stretched. 3. An apparatus for uniformly tensioning a metal material according to claim 2, characterized in that a heating means is provided for heating a portion of the metal material to be stretched. 4. An apparatus for uniformly tensioning a metallic material as set forth in claim 2, characterized in that a cooling means is provided for cooling a portion of the metallic material to which a tensile force is applied. 5. The apparatus for uniformly tensioning a metal material according to claim 2, further comprising a heating means for heating a part of the metal material to be stretched and a cooling means for cooling a part of the metal material to which a tensile force is applied. A device for uniformly tensioning metal materials.