JPS5915726B2 - Hot extrusion method for active metal tubes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for hot extruding active metal tubes, and by hot extruding without changing the viscosity of the lubricant during extrusion, seizure and rubbing between the billet and the tool can be prevented. The main purpose is to have no defects and have particularly excellent inner surface properties and morphology, and to not cause new pollution problems associated with pickling of extruded tubular bodies.

Metals such as titanium, titanium alloys, zirconium, and zirconium alloys are known as so-called active metals, but when hot extruding these active metals to obtain pipes, it is difficult to extrude the metals compared to other steel pipe extrusions. Moreover, it is extremely easy to seize with tools, and seizure due to lack of lubrication during extrusion is a very important problem in extrusion of active metals.

In other words, when the active metals mentioned above come into contact with other metals, even at low temperatures, they tend to react and form new alloys with other metals (this new alloy is more likely to form under high temperature and high pressure). Therefore, if the active metal comes into contact with the tool due to lack of lubrication between the tool and the billet during hot extrusion, the bond between the tool and the billet is very likely to seize.

Furthermore, if new alloys such as those mentioned above occur during the extrusion process, the material that is subsequently extruded will have a severely uneven surface over its entire length, which will severely deteriorate the surface condition of the product and cause it to become unusable as a product. Not only can the tool no longer be used, but the tool itself cannot be used again, which is a very serious problem in obtaining high quality active metal tubes.

In order to avoid such a situation, the inventors have put a lot of thought into it, and as a result, as disclosed in Japanese Patent Publication No. 1122 of 1982, the inventors have developed a coating made of iron on the inner peripheral surface of a tubular billet made of active metal. We proposed a method of hot extruding a layer and a coating layer made of copper on the inner peripheral surface of the iron coating layer.
Although this technology can be applied uniformly to extrusion ratios of around 10 to 50, and the product quality is excellent,
There was a problem that caused new problems in the post-processing of extruded products.

In other words, since a coating layer made of copper is formed as a shielding member, decopper removal is performed by immersion in nitric acid.
The gas generated at that time could not be completely removed using normal exhaust gas equipment, and it led to new pollution problems.
Therefore, developing an exhaust gas device that can completely remove generated gas requires the interruption of actual operations, and is problematic both economically and in terms of industrial policy.

In view of the above-mentioned circumstances, the present invention is the result of intensive research and does not change the viscosity of the lubricant during extrusion.
Succeeded in developing a hot extrusion method that enables the production of high-quality activated metal tubes, and also succeeded in developing a post-processing method that does not cause new pollution problems associated with pickling treatments, etc. Therefore, its characteristics are that a sleeve made of a material having higher deformation resistance than the billet is inserted into the inner circumferential surface of a tubular billet made of an active metal via a lubricant to form a sleeve assembly; This sleeve assembly is heated, placed in a container, and hot extruded with a mandrel inserted into the sleeve assembly to prevent the lubricant from flowing out in the counter-extrusion direction.

Hereinafter, the method for hot extrusion of active metal tubes according to the present invention will be described in detail based on the illustrated embodiments.

FIG. 1 shows a cross section of a sleeve assembly A, a billet whose inner surface has been treated prior to hot extrusion, where 1 is a tubular billet made of active metal, and 2 is the inner peripheral surface of the billet 1. A sleeve 3 is formed on the inner peripheral surface of the lubricant 2, and is made of a material with higher deformation resistance than the billet 1. In the most desirable embodiment, the tip of the sleeve 3 (in the figure, the left The extending portion 3A extends, for example, 50 m1 m from the billet end face in the extrusion direction, and the extending portion 3A is designed to substantially function as a mandrel during extrusion, and also extends in the opposite extrusion direction (right side in the figure). In this case, a flange 3B is formed on the sleeve 3, and this flange 3B is fitted into the billet end face recess 1A, so that the lubricant 2 flows out in the counter-extrusion direction not only before extrusion but also during extrusion. is being prevented.

In order to form the assembly A shown in FIG. In one case, the lubricant 2 is filled without a gap between the outer circumferential surface of the sleeve 3, and in the other, the lubricant liquefied with bi/goo like water glass is applied to the outer circumferential surface of the sleeve 3 in advance, and after drying, the lubricant 2 is In any case, it is natural that the lubricant 2 is evenly distributed, but it is desirable to provide a shield 4 at the top of the lubricant 2 to prevent the lubricant 2 from flowing out. .

The lubricant 2 contains a glass powder having a poise of about 400 to 1000 poise relative to the extrusion temperature (700°C to 900°C) and a part of graphite. -6248) lubricant, i.e., in weight percent, SiO□...28-37%, B2O
3... Section 14-17, K2O-17-22%, CaO
-1.5~6%, MgO...1~5%, pbo...
A lubricant comprising 16-36% and the remainder unavoidable impurities is preferred.

Of course, other glass or vitreous materials commonly employed in hot extrusion of active metals may also be used.

Referring to FIGS. 2 and 3, 1.2 and 3.4, the assembly (material to be extruded) A is heated at a suitable extrusion temperature (700°C to 90°C).
00°C) and hot extrusion and its extrusion behavior are illustrated.

In FIGS. 2 and 3, 5 is a container, into which the billet sleeve assembly A is inserted with the sleeve extension 3A in the extrusion direction.

A die holder 7 supporting a die 6 is supported by a die backer 8 and fitted into one end opening of the container 5, and a cylindrical ram 10 having a dummy block 9 at the tip is fitted into the other end. A mandrel support rod 13 that supports the rear end of the mandrel 11 passing through the billet sleeve assembly A via a screw plug 12 is fitted inside the billet sleeve assembly A.

Note that the 77 dorel is made of hot work tool steel.

Furthermore, a disk glass 14 is provided on the die 6 and the die holder 1 to provide lubrication between the billet 1 and the tool.

The billet 1 is pushed to the left in the figure through the advancement of the cylindrical ram 10, but the billet 1 is pushed inside and outside the extruded tube B by the annular space formed by the die 6 and the sleeve extension 3A. The diameter is set and the material is extruded at a temperature of 0.degree. C., but during this extrusion, the lubricant 2 and the mandrel 11 are separated via the sleeve 3.

It takes several seconds from the charging of the billet in FIG. 1 to the completion of extrusion in FIG. Therefore, during extrusion, the lubricant 2 maintains a uniform lubricating effect and is discharged in the extrusion direction with a uniform thickness. When the extrusion tools such as 10 and mandrel 11 are retreated as shown in FIG. 3 and 4, the sleeve 3 is pulled out together.

The above is a preferred embodiment of the present invention, but as the billet and sleeve assembly A, those illustrated in FIGS. 4 and 5 may also be adopted.

The assembly A'L shown in FIG. 4 is positioned on the same plane as the billet end face of the sleeve 3,
When hot extruding is carried out by using a tube, the temperature at the initial stage of extrusion is as shown in Fig. 6. It is desirable to provide 3A.

However, even with the assembly A' shown in FIG. 4, only the portion of the tip bevel B' causes a decrease in yield, and if this is sacrificed, the viscosity change of the extruded medium temperature lubricant 2 will be reduced. Since there is no such thing, the intended purpose can be achieved.

In addition, the assembly A" shown in FIG.
This prevents the lubricant 20 from flowing out in the opposite direction of extrusion, and although the processing is slightly more complicated than assembly A shown in FIG. 1, the intended purpose can be effectively achieved.

Next, an example of an embodiment of the present invention will be shown, and the inner surface properties of the extruded tube will be explained when the conventionally adopted stainless steel extrusion method is applied to the active metal tube hot extrusion method.

Here, the stainless steel extrusion method will be outlined with reference to FIG.

In FIG. 7, 100 is a cylindrical billet, 12
It is made of stainless steel heated to around 00°C, and has glass 101 on its outer circumferential surface and glass 102 on its inner circumferential surface.

Then, the billet 100 is charged into a container 103 and extruded at °C through an annular space defined by a die 105 having an inner glass 104 and a mandrel 106.

That is, in the case of stainless steel extrusion, the inner surface of the billet is exposed to a cold (approximately 200° C.) mandrel 106 through a glass 102.
It is extruded by contacting with.

The glass used for stainless steel is one with little viscosity change, and the billet temperature is sometimes as high as around 1200°C.The glass 102 between the billet and the mandrel does not lose its lubricating effect, but Zr.

Since the glass for Ti is an unstable glass with a low viscosity, it is easily affected by the mandrel.

Material of the sleeve 3 in the embodiment assembly A of the present invention...
・・Material of billet 1 in SUS 310 sliver assembly A・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・Titanium alloy extrusion ratio・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・42 Inner lubricant thickness ・・・・・・・・・
・・・・・・・・・・・・・・・・・・0.5711jI
lExtrusion temperature・・・・・・・・・・・・・・・・・・
At 830°C, according to the conventional method (the so-called stainless steel method), as shown in the separately attached reference photo 1 (as shown in the separately attached reference photo 1), there were scratches on the extrusion tip due to scratches. It has been found that such defects occur especially when the viscosity of the lubricant is low or when the amount is large.On the other hand, as shown in Reference Photo 2 attached separately, the present invention It can be seen that there are no rubbing defects.

In addition, as shown in reference photo 3 attached separately, according to the stainless steel method, rubbing defects occur from the center of extrusion to the rear end.
In the case of the present invention, there is no such defect as shown in Reference Photo 4 attached separately.

Furthermore, in the stainless steel method, as shown in Reference Photo 5 attached separately, seizure occurs over the entire length, and this seizure phenomenon occurs when the viscosity is high and the degree of heat taken by the mandrel is large.

In this way, as a characteristic of active metals, there is a fine line between rubbing defects and seizure, and one tends to be emphasized more than the other.This is because the extrusion temperature is intermediate compared to that of stainless steel (1200℃), However, because of its low applicability over a wide range, even a slight deviation in temperature causes a large change in viscosity.In this respect, the present invention is a method in which the lubricant on the inner circumferential surface of the billet and the mandrel are separated through a sleeve and extruded. Therefore, there is no viscosity change during extrusion of the lubricant, and there are fewer rubbing defects. Especially when the sleeve has an extension in the extrusion direction that exhibits a so-called mandrel function, This makes it possible to obtain high-quality active metal tubes with excellent inner surface properties through hot extrusion, and in addition, there is no need for deoxidation treatment of the extruded tube body, which reduces pollution problems. There is no trigger.

Note that titanium, zirconium alloys, etc.
As long as the sleeve 3 is extruded at a temperature of 50° C. and has high-temperature proof strength, the sleeve 3 is not limited to 5US310, and Hastelloy and Nimonic are more effective, but they are expensive.

Therefore, based on the temperature of the extruded material, extrusion ratio, and high temperature deformation resistance, 5US
316°5US304 may also be applicable.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a billet sleeve assembly (extruded material) according to the present invention, Fig. 2 is a sectional view of hot extrusion, and Figs. 3 1 to 3 4 are main parts of extrusion behavior and tool withdrawal. 4 and 5 are cross-sectional views of the billet sleeve assembly on the other side, and FIG. 6 is a cross-sectional view of the initial stage of extrusion using the assembly of FIG. 4. FIG. 7 is an explanatory diagram of the conventional step/less extrusion method. DESCRIPTION OF SYMBOLS 1... Billet, 2... Lubricant, 3... Sleeve, 3A... Sleeve extension part, 11... Mandrel.

Claims (1)

[Claims] 1. A sleeve made of a material with higher deformation resistance than the billet is inserted into the inner peripheral surface of a tubular billet made of active metal via a lubricant to form a sleeve assembly, and this sleeve assembly is heated. hot extrusion of an active metal tube, characterized in that the active metal tube is charged into a container and hot extruded with a mandrel inserted into the sleeve assembly to prevent the lubricant from flowing out in a counter-extrusion direction. Extrusion method. 2. The method for hot extruding an active metal tube according to claim 1, wherein the sleeve of the sleeve assembly extends in the extrusion direction from the end face of the billet.