JPH03180207A - Die for extruding titanic material to be formed - Google Patents

Abstract

PURPOSE:To prevent generation of linear flaws due to seizure by making at least the inner face of hole on a side, which the product of the distance from the centroidal point of the front shape of a die hole and the length of side is maximum, into a prescribed roughness. CONSTITUTION:The side which the product of the distance from the centroidal point 5 and the length of side is maximum is the side of 57.7mm long situated on X-axis. Therefore, the inner face of the die hole on the side of 57.7mm long is finished in <=Ra 10mum of roughness by grinding with a buff, sandpaper and wet type grinding wheel, etc. And the inner faces of die holes on other sides may be finished in <=Ra 10mum of roughness or made into usual finishing with a grinder or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a titanium profile extrusion die used for hot extrusion of titanium profiles. In this specification, titanium means pure titanium or a titanium alloy unless otherwise specified.

[Conventional technology]

Manufacture of a shape material by hot extrusion is performed by inserting a heated billet into a container and then inserting the billet into a die hole of a die in a lubricated state using a stem. The cross-sectional shape of the manufactured mold material matches the front shape of the die hole. FIG. 1O shows a die used in the production of L-profiles.

The die hole 2 of the die l has an L-shaped front view, and the entrance side of the hair ring part 3 that determines the shape of the mold material is an approach part 4 that is gradually narrowed toward the bearing part 3.

Die materials such as die steel, high-speed steel, and cemented carbide are known, but although high-speed steel and cemented carbide have excellent heat resistance and wear resistance, they are expensive, so die steel is often used. Therefore, dies made of die steel are often used for extruding titanium shapes.

[Problem to be solved by the invention]

However, when hot extruding a titanium profile using an extrusion die made of inexpensive die steel, even if sufficient lubricant is supplied between the inner surface of the die hole and the material surface, It is inevitable that some seizure will occur, and the surface of the extruded titanium profile will have streaks in the extrusion direction due to seizure.

The present invention was made in view of the above situation, and an object of the present invention is to provide a die for extruding a titanium profile material that can prevent scratches due to seizure from occurring on the surface of the profile material even when die steel is used as the raw material. shall be.

[Means for solving the problem] It is clear that the seizure that occurs during hot extrusion of titanium shapes is similar to that of general steel materials, and is caused by insufficient lubrication. Technologies to improve lubricity during hot extrusion include:
A die in which the inner surface of the die hole is made into a finely uneven surface and the lubricant is trapped on this uneven surface was developed in 1983.
It is disclosed in Japanese Patent No.-13287. According to research conducted by the present inventors, this die is effective for easily processable materials such as aluminum alloys, but is hardly effective for difficult processable materials such as titanium.

In light of this situation, the present inventors have conducted various studies on countermeasures against seizure when hot extruding titanium shapes from a different perspective than lubricant tramping, and have obtained the following knowledge. .

The seizure that occurs during hot extrusion of titanium profiles is affected by the roughness of the inner surface of the die hole, but the tendency is opposite to that of lubricant trapping, where the flatter the inner surface of the die hole is, the more seizure occurs. It becomes difficult. In addition, when looking at the extruded titanium mold material, the streaks due to seizure do not occur evenly on each surface, but are concentrated on a specific surface, and that surface is the die hole. This is the surface that was in contact with the inner surface of the die hole of the side that has the largest product of the distance from the center of gravity and the side length in the front shape of the die hole.

The present invention has been made based on the above findings, and the inner surface of the die hole of at least the side surrounding the die hole where the product of the distance from the center of gravity and the length of the side in the front shape of the die hole is the largest, has a Ra of 10 μm. The gist is a die for extruding titanium shapes with the following roughness.

[Function] By smoothing the inner surface of the die hole, the die of the present invention can reliably prevent seizure during hot extrusion of a titanium profile even if the die material is inexpensive die steel. .

The reason why the inner surface of the die hole to be smoothed is the inner surface of the die hole of the side where the product of the distance from the center of gravity and the length of the side in the front shape of the die hole is at least the largest among the sides surrounding the die hole. This is because it has become clear from statistical analysis of a large number of operational results that streaks due to seizure occur intensively on the surface of the mold material that was in contact with the inner surface of the die hole.

The reason why the roughness of the inner surface of the die hole to be smoothed is less than I Oam is that if it exceeds 0 μm, it is not possible to prevent scratches due to seizure from occurring on the surface of the mold material. It is thought that this is because a lubricating film with a uniform thickness is formed between the inner surface of the die and the material surface, making it difficult for local film breakage to occur due to stress concentration.

(Example) Examples of the die for extruding titanium profile materials of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the front shape of the die hole, particularly the hair ring part, in the die of the present invention, (a) is a dimensional drawing thereof, and (b) is a drawing schematically showing the shape of the die hole. The front shape of the hair ring part is L-shaped, and the length is 51.
The 1m side is the X axis, the length perpendicular to this side is 44.5 + m
If the side of a is the y-axis, the center of gravity 5 in the front shape of the hair ring is expressed in x-y coordinates (16, 7, 18,
0).

That is, if the front shape of the bearing part is divided into two rectangles A and B as shown in Fig. 1(b), the center of gravity 5 (
x, y) are expressed as 1/2A x XA+1/2B x X BA + BA+B.

However, Ax, By: Length of rectangle A and rectangle B in the X-axis direction Ay, By: Length of rectangle A and rectangle B in the y-axis direction A, B: Area of rectangle A and rectangle B, and
In the die shown in FIG. 1, the side with the largest product of the distance from the center of gravity 5 (x, y) and the side length is located on the X axis and has a length of 57.
The sides will be 7 mm. Therefore, with this die, length 5
The inner surface of the die hole on the 7.7 mm side has a roughness of Ra10.
Finished to below μm. In order to make the inner surface of the die hole have an Ra of 10 μm or less, it may be performed by, for example, puff polishing, polishing with sandpaper, wet grindstone polishing, or the like.

The inner surface of the die hole on the other sides may be finished to an Ra of 10 μm or less, or may be finished normally by a grinder or the like with an Ra of about 15 μm. Note that the inner surface of the die hole whose Ra is 10 μm or less refers to each surface of the bearing portion and the approach portion that come into contact with the material.

The die whose hole shape is shown in FIG. 2 is a die used for extruding T-shaped materials, and in the case of this die, the center of gravity 5 in the front shape of the die hole is located at (20, 122, 5),
The side with the maximum product of the distance from the center of gravity 5 and the side length has a length of 41.4I1m.

Therefore, in this die, the inner surface of the die hole on at least the side having a length of 41.4 m among each side is made to have a Ra of 10 μm or less.

Similarly, in the dies whose hole shapes are shown in FIGS. 3 to 9,
The center of gravity and the side with the maximum result are as shown in Table 1, and the inner surface of the die hole is set to have an Ra of 10 μm or less for one or more sides including at least the side with the maximum result.

Table 1 Next, the results of actual hot extrusion of a titanium profile using the die shown in FIG. 1 will be described.

After heating a billet with a diameter of 174 m+a made of AMS4936A (Ti-6Al-6V-23n) to 1060°C, the billet was inserted into a container, and then it was lubricated through the die hole of the die at a speed of 300 mm/sec using a stem. Extruded. The die is made of 5KD61 die steel, and the inner surface of the die hole is adjusted to a constant roughness on all sides, and the roughness (Ra) is 1um, 10μm,
There were three types of 15 gm.

The surface roughness of the extruded L-shaped material was suppressed to 2 to 4 .mu.m on all surfaces of the die hole when the surface roughness of the inner surface of the die hole was 7 .mu.m. Similarly, when the die hole inner surface roughness was 10 .mu.m, the roughness was suppressed to 7 to 9 .mu.m on all surfaces of the mold material. but,
When a die with a die hole inner surface roughness of 15 μm was used, streaks were generated on the surface of the mold material that was in contact with the side marked with side i57.7, making it impossible to measure the roughness.

Also, when using a die with a T-shaped die hole as shown in Figure 2, when the die hole inner surface roughness was 7 μm, the surface roughness of the mold material was kept at 2 to 4 μm, and even when the die hole was 10 μm, it was suppressed to 7 to 10 μm. , with a roughness of 15 μ copper, the side length is 41.4 mm.
Lines appeared on the surface of the mold material that was in contact with the edges, making it impossible to measure the roughness.

[Effects of the Invention] As explained above, the titanium profile extrusion die of the present invention prevents the occurrence of streaks due to seizure even when hot extrusion is performed using a die made of inexpensive die steel. As a result, the die cost does not increase and there is no need for rework after extrusion, making it possible to efficiently produce high-quality titanium shapes with good surface properties at low cost.

[Brief explanation of drawings]

FIG. 1(a) is a dimensional diagram showing an example of the front shape of the die hole in the die of the present invention, FIG. 1(b) is a schematic diagram for explaining the method of calculating the center of gravity position, and FIGS. Dimensional drawing showing the front shape of the die hole in another die of the invention, 1st
FIG. 0(a) is a front view of a conventional extrusion die, and FIG. 0(b) is a sectional view taken along the line [-1] of FIG. 0(a). 1 Die, 2: Die hole, 5; Center of gravity Applicant: Sumitomo Metal Industries, Ltd. (b) Figure 5 Funeral Diagram 704 Figure 4゜

Claims (1)

[Claims] (1) A die for extruding a shape material made of pure titanium or titanium alloy, in which at least the product of the distance from the center of gravity and the length of the side in the front shape of the die hole is the largest among the sides surrounding the die hole. The inner surface of the die hole on the side is Ra10μm
A die for extruding titanium shapes, characterized by having the following roughness: