JPH03258424A - Die for forming aluminum can made of tungsten carbide base sintered hard alloy - Google Patents

Abstract

PURPOSE:To prolong the life of a die for forming an aluminum can by specifying the content of Cr in tungsten carbide base sintered bard alloy and specifying the diameters of fine grains of the tungsten carbide and tantalum carbide. CONSTITUTION:Cr of 0.16-0.48wt.% for the rate shared in the whole enter into sold solution in Co of a bonded phase forming component of the tungsten carbide base sintered bard alloy and the tungsten carbide and tantalum carbide being dispersed phase forming components are composed of fine grains having average grain diameter <=2mum. In this way, wear resistance can be improved and excellent corrosion resistance can be given to a working die for drawing an aluminum can, the life of the die can be prolonged and the finished surface of the aluminum can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides aluminum (Aρ) cans which not only have excellent wear resistance and corrosion resistance, and therefore have a long service life, but also have a clean finished surface. Made of moldable tungsten carbide (hereinafter referred to as WC)-based cemented carbide A
This relates to a mold for forming Ω cans.

[Conventional technology]

Conventionally, in general, in the production of Al1 can molding molds, Co: 6 to 12% is used as a binder phase forming component, and tantalum carbide (hereinafter TaC) is used as a dispersed phase forming component. ): 6 to 2
A WCC cemented carbide having a composition of 0%, and the remainder consisting of WC as a dispersed phase forming component and unavoidable impurities is used.

[Problem to be solved by the invention]

However, in the above-mentioned conventional A1 can forming mold made of WC-based cemented carbide, the raw material powder is fine, e.g.
Even if WC powder or TaC powder is used, it is impossible to avoid grain growth during sintering, and after sintering, it becomes coarse grains with an average grain size of 5 or more, and as a result, the binder phase Formation of a pool was observed, and in the case of A and Q can bottom shapes, the direct contact area between Co as a binder phase forming component and 11, which is the material to be formed, is large, so the wear progresses quickly and takes a relatively short time. In addition to reaching the end of its service life, there are other problems such as the binding phase being corroded by the cooling water used when forming the Ap can bottom, and the finished surface of the Al1 can being easily scratched because WC and TaC are coarse particles.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors conducted research focusing on the above-mentioned WCC cemented carbide in order to develop an Al1 can forming mold with excellent wear resistance and corrosion resistance. When Cr is contained as a solid solution in Co as a phase-forming component to form a Co-Cr alloy, the grain growth of WC and TaC as dispersed phase-forming components during sintering is suppressed by the action of this Cr. It has been refined to an average particle size of 21! In a structure where WC and TaC have become fine particles with an average particle size of 2 or less, there is no formation of a binder phase pool, and the binder phase is extremely thin between the dispersed phase particles. As a result, during can manufacturing, the proportion of direct contact between the binder phase and Al of the workpiece material is drastically reduced, and the contact between fine WC and TaC and the workpiece material slows down the progress of wear. significantly suppressed,
In addition, the C0Cr alloy binder phase has excellent corrosion resistance, so
Research has shown that a clean surface finish can be obtained.

This invention was made based on the above research results, and contains Co: 4 to 12% as a binder phase forming component, TaC as a dispersed phase forming component: 6 to 20%, and the remainder is a dispersed phase forming component. In a WCC cemented carbide having a composition consisting of WC as a component and unavoidable impurities, 0.16 to 0.48% of Cr is contained as a solid solution in Co as a binder phase forming component. At least, the average particle size of WC and TaC as the dispersed phase forming components is 2.
W made of WCC cemented carbide with fine grains less than ts
It is characterized by A and Q can bottom molds made of C-based cemented carbide.

Next, the reason why the component composition in the mold of the present invention is limited as described above will be explained.

(a) C.

The Co component has the effect of improving the strength of the mold, but
If the content is less than 4%, the desired strength improvement effect cannot be obtained, while if the content exceeds 12%, a binder phase pool will be formed and the wear resistance will decrease. Therefore, its content was determined to be 4 to 12%.

(b) Cr The Cr component contains Co-Cr, which is dissolved in Co as described above.
By forming an alloy, it suppresses the grain growth of WC and TaC during sintering, and maintains the grain size at an average grain size of 2 or less, thereby improving the wear resistance of the mold and improving the wear resistance of the mold itself. It has the effect of forming a binder phase and contributing to improving corrosion resistance, but if its content is less than 0.16%, the desired effect cannot be obtained; If the proportion exceeds 0.48% of the total, carbides will precipitate in the binder phase and the strength will decrease, so the content was set at 0.16 to 0.48%. .

(c) TaC The TaC component has excellent solid lubricity and is a component that exhibits poor weldability to Al, which is the can material to be made.
TaC is an essential component of can-making molds, but if its content is less than 6%, the above-mentioned properties of TaC cannot be fully exhibited, while if its content exceeds 20%, , the proportion of WC is relatively small, and TaC
Since WC is softer than WC, it causes a decrease in wear resistance, so its content is set at 6 to 20%.

In addition, in the mold of this invention, the average particle size of WC and TaC as dispersed phase forming components is set to be 2 μs or less, because if the average particle size exceeds 2 - and becomes coarse, bonding will occur as described above. This is based on the reason that phase pools are more likely to be formed, and as a result, the progress of wear in this area becomes significantly faster, or the finished surface is more likely to be damaged by the coarse dispersed phase.

〔Example〕

Next, the mold of the present invention will be specifically explained using examples.

WC powder, TaC powder, CO powder, and Cr powder each having an average particle size shown in Table 1 were prepared as raw material powders, and these raw material powders were blended in the proportions also shown in Table 1, After mixing in a ball mill for 72 hours,
The powder body is press-formed under a pressure of 5 ton/c-, sintered in a vacuum at a predetermined temperature within the range of 1300 to 1500°C, and then finished by grinding. :Hm+wφ×Wall thickness: Hollow cylindrical hollow cylindrical Aρ can drawing molds 1 to 4 of the present invention and conventional Al can drawing molds 1 and 2 were manufactured, respectively.

Next, these various Al can drawing molds were used in the fourth stage of a four-stage drawing process, and two
At a can making speed of 50 cans/sin, diameter: 6h + mφ x length =
150 mm x wall thickness: O, Hm aluminum cans are drawn,
The number of cans produced until the end of its service life was measured. Also, Al
The surface condition of one can was also observed. These results are shown in Table 1.

〔Effect of the invention〕

From the results shown in Table 1, in all of the Al can drawing molds 1 to 4 of the present invention, WC and TaC constituting the dispersed phase become fine particles due to the action of Cr contained in solid solution in the binder phase. Since the drawing process is essentially a direct contact between the work material AN and the dispersed phase, it exhibits excellent wear resistance, and the binder phase itself also has excellent corrosion resistance. In addition to exhibiting a long service life, Al cans also have a beautiful finished surface.
In the one-can drawing molds 1 and 2, even if fine powder is used as the raw material powder, the dispersed phase becomes coarse particles due to grain growth during sintering, so during drawing, the binder phase and Ap of the workpiece are As a result, the wear of the binder phase progresses, resulting in a relatively short service life.Furthermore, the coarse dispersed phase causes scratches, and it is clear that the finished surface is cloudy. be.

As mentioned above, the AΩ can molding die of the present invention has a long service life, and the Al cans produced therewith have industrially useful properties such as a clean finished surface.

Claims (1)

[Claims] (1) A composition containing Co: 4-12% by weight as a binder phase-forming component, tantalum carbide: 6-20% by weight as a dispersed phase-forming component, and the remainder consisting of tungsten carbide as a dispersed phase-forming component and unavoidable impurities. In the tungsten carbide-based cemented carbide having a composition, 0.16 to 0.48% by weight of Cr is contained as a solid solution in Co as the binder phase forming component to form the dispersed phase forming component. A mold for forming an aluminum can made of a tungsten carbide-based cemented carbide, characterized in that it is made of a tungsten carbide-based cemented carbide made of fine particles of tungsten carbide and tantalum carbide with an average particle size of 2 μm or less.