JPH0335824A - Method for deep drawing titanium sheet - Google Patents

Abstract

PURPOSE:To prevent seizure in composite forming by forming a titanium sheet with sandwiching fluoroplastic or polyolefin sheets having a specified thickness between both sides of the titanium sheet. CONSTITUTION:The titanium sheet 4 is deep-drawn by using a punch 1, a die 2 and a blank holder 3. Then the titanium sheet is formed with sandwiching the fluoroplastic or polyolefin sheets 5, 5 having a thickness 0.07-0.2mm between both sides of the titanium sheets 4. In this way, the deep drawing limits of the titanium sheet can be improved.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention provides a sink for a sink, a bathtub, and a bathtub using thin titanium plates.
This relates to a method for forming deep drawn parts such as automobile parts.

(Prior technology) Due to its strength and corrosion resistance, titanium is widely used in aircraft, chemical plants, ships, etc. Recently, titanium thin sheets have been deep-drawn and used for sinks, bathtubs, automobile parts, etc. Application to deep-drawn parts has begun to be considered. However, when performing deep drawing, titanium tends to seize in the mold, which not only causes galling defects on the plate and impairs its commercial value, but also reduces the forming limit, which limits its application.

The reason why seizure tends to occur in the mold is as follows. Titanium naturally has a good affinity with carbon and nitrogen in steel, making it easy to form compounds such as TiC and TiN. When tool steel containing a large amount of carbon in steel is used for a mold, if the surface of the mold comes into contact with the surface of titanium, TiC is generated on the surface of the mold, causing burn-in on the surface of the mold.

This TiC is hard, and not only does it further scrape the surface of the thin titanium plate, which is softer than tool steel, causing galling, but it also increases the coefficient of friction between the mold and titanium, making it difficult for titanium to flow in and reaching the forming limit. decreases.

If a mold made of tool steel is used in this way, seizure will occur, so it is possible to use other plastic molds or cement molds, but these tools are not common, and the size and size of the tool There are problems with the accuracy and durability of the surface finish.

It is also possible to use sweat oil or high viscosity lubricant containing extreme pressure additives as the lubricant2, but in this case as well, metal contact between the titanium and the mold is unavoidable and it is difficult to prevent seizure. In addition, a step for removing O lubricating oil is required after molding, which increases manufacturing costs.

(Problems to be Solved by the Invention) To prevent seizure that occurs when deep-drawing a thin titanium plate using a mold using tool steel.1 To improve the deep-drawing limit of a thin titanium plate.C.

It is essential for improving the surface quality of products.

The present invention provides a method for forming a thin titanium plate 6 that can prevent seizure in a t-composite type in which stretch forming and drawing are performed simultaneously.

(Means for Solving the Problems) In order to solve the above problems, the present inventors completed an FF study, and in deep deterioration forming of titanium thin plates, the thickness ranges from 0.07 to 0.21. This is a deep drawing method for thin titanium plates, which is characterized by forming sheets of fluorine resin or polyolefin on both sides with scissors.

(Function) The reason why the present invention can prevent seizure that occurs when deep drawing a titanium thin plate is considered to be as follows.

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

Table 1 shows the material and thickness of the titanium thin plate, the usage method and thickness of the fluororesin or polyolefin sheet, and the critical drawing ratio and degree of seizure on the mold for cylindrical deep drawing and square cylinder deep drawing. This is a survey of molding.

Here, the critical drawing ratio is the value obtained by dividing the maximum blank size that can be formed without wrinkles or cracks by the punch dimension, and in the case of cylindrical deep drawing, it is the value obtained by dividing the blank diameter by the punch diameter. In the case of square cylinder deep drawing, it is the value obtained by dividing the length of one side of the square blank by the length of one side of the punch.

The higher the limit drawing ratio, the better the formability, and the higher the limit drawing ratio, the better the formability.

Formability is improved not only when forming with a square or square punch, but also when forming into a long sword shape or other complex shapes.

Table 2 shows the ingredients contained in the titanium thin plates used and their mechanical properties. Types 1 and 2 are JIS H
As a representative example of the 4600 classification, a case with a plate thickness of 0.85u is compared.

Figure 2 shows a polytetrafluoroethylene sheet formed from a JIS 1 type titanium thin plate with a thickness of 0.95 mm in Table 2 using a rectangular cylinder punch with a square shape of 75 sides. 3 is a graph showing the critical drawing ratio and the failure state of a polytetrafluoroethylene sheet when the thickness of the polytetrafluoroethylene sheet is changed.

When a fluororesin or polyolefin sheet is sandwiched between both sides and molded as shown in FIG. 1, the critical drawing ratio is greatly improved as shown in Table 1 and FIG. 2.

For example, as shown in Figure 142, when forming with a square cylinder punch of 75 mm on a side using JIS 1 type plate thickness 0.9 tsm, do not use polytetrafluoroethylene and apply anti-rust oil to both sides. When it is coated and molded, the limiting drawing ratio is 2.07, but the thickness is 0.07~0.
When molding with 20 gm of polytetrafluoroethylene placed on both sides, the critical drawing ratio reaches 2.80, which is 0 compared to the former.
．． 73 will also improve.

This effect of improving the limit drawing ratio is an incredible effect when compared with the case of forming a steel plate of ordinary steel. For example, in the case of cold-rolled steel sheets made of ordinary steel, G3L according to the JIS standard.
As the steel plate for general use (SPCC) shown in No. 41 is changed to steel plate for drawing (SPCD) and steel plate for deep drawing (S P CE), the critical drawing ratio usually increases by around 0.1.

In other words, raise the material grade by 2 ranks and increase from 5pcc to 5P.
Even if you change to CE, the limit drawing ratio will only improve by around 0.2. On the other hand, when polytetrafluoroethylene sheets are sandwiched between both sides of a thin titanium plate and formed, the critical drawing ratio is improved by 0.73 compared to when there is no sandwiching, which is much more significant than changing the material grade. It can be seen that this has the effect of improving deep drawing formability.

However, if this polytetrafluoroethylene sheet is too thin, it will break during molding and cause seizure, leading to a decrease in the critical drawing ratio, so the thickness should preferably be 0.07 mm or more. Moreover, if it is too large, it will not only increase the manufacturing cost (but also cause wrinkles that occur on the flange part during molding to be easily printed on the titanium thin plate, causing a decrease in the critical drawing ratio. Therefore, the upper limit was set at 0.2 m.

In addition, even if a polytetrafluoroethylene sheet is used on only one side, it will cause burn-in on the unused side.
The improvement in the limit drawing ratio is also small and not appropriate. If a polytetrafluoroethylene sheet is not available, another fluororesin sheet or a polyolefin sheet such as polyethylene or polypropylene may be used, but the effect of improving the critical drawing ratio will be small.

Further, as shown in FIG. 1, other advantages of molding by sandwiching fluororesin or polyolefin sheets on both sides include the following points.

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

Fluororesin or polyolefin sheets are on both sides and act as a lubricant, and the thickness of the sheet is 0.07 mm.
This is because if the thickness is 0.2 mm, the sheet will not be damaged until the molding is completed, so the titanium surface and the mold surface will not come into direct contact and will not be affected by the surface finish such as the surface roughness of titanium.

Next, there is no need to use lubricating oil containing extreme pressure additives or high viscosity, and the degreasing process after molding can be omitted or simplified.

(Effects of the Invention) The present invention is extremely effective for deep drawing of titanium thin plates. In addition, it has a seizure prevention effect not only for deep drawing, but also for other stretch forming using molds and composite forming where drawing and stretch forming are performed simultaneously for complex shapes, and has a wide range of applications. It is wide.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the present invention in which a titanium thin plate is formed by sandwiching a polytetrafluoroethylene sheet on both sides, and Figure 2 shows the critical drawing ratio and polytetrafluoroethylene sheet thickness change. It is a chart showing the state of sheet damage of tetrafluoroethylene. Agent Patent Attorney Tate Chanogi Mistake 2 θl θ2

Claims (1)

[Claims] 1. A method for deep drawing a thin titanium plate, which comprises forming a sheet of fluororesin or polyolefin having a thickness of 0.07 mm to 0.2 mm on both sides.