JPH067966B2 - Deep drawing method for titanium sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a sink for sink, a bath,
The present invention relates to a method of forming deep drawn parts such as automobile parts.

(Prior Art) Titanium is widely used in aircrafts, chemical plants, and ships due to its strength and corrosion resistance. Recently, titanium sheets have been deep-drawn to form sinks for sinks, bathtubs, automobile parts, etc. Application to deep drawing parts has begun to be considered. However, when deep drawing is performed, titanium is apt to cause seizure in the mold, which not only causes galling and scratches on the plate to impair the commercial value, but also lowers the molding limit, limiting the application.

The reason why seizure is likely to occur on the mold is as follows. Titanium originally has an affinity for carbon and nitrogen in steel and easily forms compounds such as TiC and TiN. When tool steel containing a large amount of carbon in steel is used for the die, when the die surface comes into contact with the titanium surface or TiC is formed on the surface of the mold, causing seizure on the surface of the mold.

This TiC is hard and not only scratches the surface of the titanium thin plate, which is softer than tool steel, to cause galling flaws, but also increases the friction coefficient between the mold and titanium, making it difficult for titanium to flow in and forming limit. Is reduced.

Since seizure occurs when a mold using tool steel is used in this way, other plastic molds or cement molds may be considered, but these tools are not common, and the size and There is a problem with the accuracy and durability of the surface finish.

It is also possible to use a lubricating oil containing an extreme pressure additive or a high-viscosity lubricating oil as the lubricating oil, but even in this case, metal contact between titanium and the mold cannot be avoided and seizure prevention is difficult. However, the manufacturing cost is increased because a step of removing the lubricating oil after molding is required.

(Problems to be solved by the invention) Preventing seizure that occurs when a titanium thin plate is deep-drawn by a mold using tool steel improves the deep-drawing limit of the titanium thin plate and also improves the surface quality of the product. It is essential for improvement.

The present invention provides a method for forming a titanium thin plate capable of preventing seizure in composite forming in which stretch forming and drawing are performed at the same time.

(Means for Solving the Problems) The present inventors have completed the results of various studies in order to solve such problems, and in the deep drawing of a titanium thin plate, the thickness of the titanium thin plate was 0 without applying a lubricating oil. 0.1 mm to 0.
This is a deep-drawing method for a titanium thin plate, characterized in that a sheet of 2 mm fluororesin or polyolefin is sandwiched between both sides and molded.

(Operation) The reason why the seizure that occurs when the titanium thin plate is deep-drawn by the present invention can be prevented is considered as follows.

Figure 1 shows a method of forming a titanium thin plate by sandwiching a fluororesin or polyolefin sheet on both sides.
1 is a punch, 2 is a die, 3 is a wrinkle retainer, 4 is a titanium thin plate, and 5 is a fluororesin or polyolefin sheet.

Table 1 shows the material and thickness of the titanium thin plate, the method of using the fluororesin or polyolefin sheet and the limiting drawing ratio and the degree of seizure on the die when the thickness is changed. This is a survey on molding.

Here, the limit drawing ratio is a value obtained by dividing the size of the largest blank that can be formed without wrinkling and cracking by the punch size, and in the case of cylindrical deep drawing, the diameter of the blank is divided by the diameter of the punch. The value is the value obtained by dividing the length of one side of the square blank by the length of one side of the punch in the case of deep drawing of a rectangular tube.

The higher the limit drawing ratio, the better the moldability, and the moldability is improved not only when the punch has a cylindrical shape or a square shape, but also when the rectangular shape or another complicated shape is used.

Table 2 shows the components contained in the titanium thin plate used and the mechanical properties thereof. The 1st and 2nd types compare the case of 0.65mm plate thickness as a representative example of JIS H4600.

Fig. 2 shows the thickness of the polytetrafluoroethylene sheet when the titanium thin plate of JIS Class 1 0.95 mm thick was used to form a square rectangular punch with a side of 75 mm. It is a graph which shows the limit drawing ratio when changing and the damage state of the sheet of polytetrafluoroethylene.

When a sheet of fluororesin or polyolefin is sandwiched between both sides as shown in FIG. 1, the limiting drawing ratio is greatly improved as shown in Table 1 and FIG.

For example, as shown in FIG. 2, JIS 1 type plate thickness 0.95
When forming with a square-shaped square cylinder punch with a side of 75 mm using mm, if you use rust preventive oil on both sides without using polytetrafluoroethylene and mold, the limiting drawing ratio is 2.07, whereas When a 0.1-0.2 mm thick polytetrafluoroethylene is placed on both sides and molded, the limiting drawing ratio is 2.
It reached 80 and improved by 0.73 compared to the former.

The effect of improving the limiting drawing ratio is an incredible effect when compared and compared when forming a steel plate of ordinary steel. For example, in the case of cold rolled steel plate of ordinary steel, JIS standard G3141
From the general-purpose steel plate (SPCC) shown in Fig. 2 to the drawing steel plate (S
The limit drawing ratio is usually improved by about 0.1 with the increase in PCD) and deep drawing steel plate (SPCE).

That is, the material grade is increased by 2 ranks and SPCC to SP
Even if it is changed to CE, the limiting aperture ratio is improved only by about 0.2. On the other hand, when a sheet of polytetrafluoroethylene is sandwiched on both sides of a titanium thin plate,
It can be seen that the limit drawing ratio is improved by 0.73 as compared with the case where it is not sandwiched, and there is a marked improvement effect of deep drawing formability rather than a change in material grade.

However, if this sheet of polytetrafluoroethylene is too thin, it will be damaged during the molding and seizure will occur, leading to a reduction in the limiting drawing ratio. Therefore, the thickness is preferably 0.1 mm or more. If it is too thick, not only the manufacturing cost will increase, but also wrinkles that occur in the flange portion during molding will be easily printed on the titanium thin plate, and this will cause a reduction in the limiting drawing ratio, so the upper limit was made 0.2 mm.

Also, even if you use a sheet of polytetrafluoroethylene on only one side, seizure will occur on the unused side,
The improvement of the limit draw ratio is also small and not appropriate. When there is no polytetrafluoroethylene sheet, other fluororesin sheets or polyolefin sheets such as polyethylene and polypropylene may be used, but the effect of improving the limiting drawing ratio becomes small.

In addition, as shown in FIG. 1, the following points can be raised as another advantage of forming a sheet of fluororesin or polyolefin on both sides.

First, a high limiting drawing ratio can be obtained regardless of the surface finish such as the surface roughness of titanium.

Fluorine resin or polyolefin sheet is on both sides and acts as a lubricant, and the thickness of the sheet is 0.1mm.
If the thickness is 0.2 mm, the sheet will not be damaged until the molding is completed, and the titanium surface and the mold surface do not come into direct contact with each other, and the surface finish such as the surface roughness of titanium is less likely to be affected.

Next, it is not necessary to use a lubricant containing an extreme pressure additive or a lubricant having a high viscosity, and the degreasing step after molding can be omitted or simplified.

(Effect of the Invention) The present invention is extremely effective for deep drawing of a titanium thin plate. In addition to deep-drawing, it also has the effect of preventing seizure not only for other overhang forming using a die and for composite forming in which draw forming and tension forming are performed at the same time in a complicated shape, and it is extremely applicable. It is wide.

[Brief description of drawings]

FIG. 1 is an explanatory view of the present invention in which a titanium thin plate is formed by sandwiching a polytetrafluoroethylene sheet on both sides, and FIG. 2 is a limiting drawing ratio and polytetrafluoroethylene for a change in the sheet thickness of polytetrafluoroethylene. 5 is a chart showing a sheet damage state of FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-55-149727 (JP, A) JP-B-51-3702 (JP, B1) JP-B-55-18171 (JP, B2) "Press Technology" ( Vol. 22, No. 4), Nikkan Kogyo Shimbun, pp. 35-40

Claims (1)

[Claims] Claim: What is claimed is: 1. In deep drawing of a titanium thin plate having excellent seizure resistance, a thickness of 0.1 is obtained without applying lubricating oil.
A deep-drawing method for a titanium thin plate, which comprises forming a sheet of fluororesin or polyolefin of mm to 0.2 mm on both sides.