JP2003001344A - Mold for press forming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for press forming which is excellent in abrasion resistance and buildup resistance, and can be used continuously for a long time. SOLUTION: Pulverized buildup spraying material consisting of Cr of 15-40 weight %, Al of 5-20 weight %, Y of 2 or less weight % and the rest of Ni and/or Co is welded to the press forming face of the mold body made of alloy tool steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die for press molding which has excellent wear resistance and build-up resistance and can be continuously used for a long time.

[0002]

2. Description of the Related Art For example, a product such as an automobile door panel is produced by continuously pressing a steel plate with a press molding die. However, due to continuous use over a long period of time, the phenomenon that a so-called build-up is formed on the press forming surface of the forming die due to the adhesion and deposition of the steel sheet and the adhered oxide on the steel sheet, There was a phenomenon that the press-molded surface of the mold was worn. If this buildup or wear occurs, the surface of the steel sheet will be scratched and the quality will deteriorate.Therefore, the operation of the press molding machine is stopped periodically to polish the die or replace it with a new die. Or
There was a problem that it adversely affected productivity.

Therefore, there has been proposed one in which a thermal spray coating such as ceramic is formed on the press molding surface of a molding die to improve wear resistance and build-up resistance. There is a problem that it is easily peeled off by impact and cannot be applied to continuous use for a long time. On the other hand, a product such as an automobile door panel is made of a higher strength steel sheet which is warm (about 400 to 850 in the present invention).
There is a tendency for press working within a range of 0 ° C.), and there has been a demand for development of a press-molding die that can withstand continuous use for a long time even under such conditions.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and is excellent in wear resistance and build-up resistance and can be continuously used for a long time. The present invention has been completed for the purpose of providing a press-molding die that can be continuously used without causing any trouble even when it is pressed by.

[0005]

The press-molding die of the present invention made to solve the above-mentioned problems is 15-40% by weight on the press-molding surface of the mold body made of alloy tool steel.
Of Cr, 5 to 20% by weight of Al, 2% by weight or less of Y, and the balance of Ni and / or Co, and a powder overlay material was overlay welded.

Further, the invention according to claim 2 is one in which the alloy tool steel is SKD11 or SKD61.
Further, the powder build-up material containing an oxide dispersant is defined as the invention according to claim 3, and the oxide dispersant is aluminum oxide, chromium oxide, titanium dioxide, silicon dioxide, zirconium oxide. The invention according to claim 4 includes one or more of magnesium oxide, magnesium oxide, yttrium oxide, and a rare earth oxide.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be shown below. The press-molding die of the present invention is used for warm-pressing a high-strength steel sheet (in the present invention, in the range of about 400 to 850 ° C.), for example, for pressing a door panel for an automobile. It is used in press molding dies for molding. In the present invention, the mold body is SKD1, S
It is made of alloy tool steel such as KD11 or SKD61, and the press-molding surface of the die body has 15 to 15
The powder overlay material is 40% by weight Cr, 5 to 20% by weight Al, 2% by weight or less Y, and the balance is Ni and / or Co. By applying such overlay welding, it has excellent wear resistance equivalent to that of a ceramic sprayed coating, and can also maintain high adhesive strength. Furthermore, it has low reactivity and does not easily cause adhesion and build resistance. It also has an excellent effect on the up property.

The above-mentioned Cr is for forming an oxide protective film at 800 ° C. or lower to impart oxidation resistance, and its content is preferably in the range of 15 to 40% by weight. If it is less than 15% by weight, this effect is not sufficient, and if it exceeds 40% by weight, the alloy phase becomes brittle. Al is for promoting the formation of an alumina protective film at 800 ° C. or higher and the formation of a chromium oxide protective film at 800 ° C. or lower, and the content thereof is 5 to 5.
A range of 20% by weight is preferred. If it is less than 5% by weight, this effect is not sufficient, and if it exceeds 20% by weight, the alloy phase becomes brittle like chromium. The above chromium oxide or alumina protective film has excellent build-up resistance. Y is for improving the oxidation resistance, and its content is preferably 2% by weight or less. The balance consists of Ni or Co, or Ni and Co.

Further, the powder build-up material may contain an oxide dispersant. This oxide dispersant improves wear resistance and is uniformly dispersed in the alloy at a ratio of 2% by volume or less. If it is more than 2% by volume, the oxidation resistant alloy may become brittle and the thermal shock resistance and adhesion of the welded portion may be deteriorated, which is not preferable. As a specific oxide dispersant, one kind or two or more kinds of aluminum oxide, chromium oxide, titanium dioxide, silicon dioxide, zirconium oxide, magnesium oxide, yttrium oxide, and rare earth oxide can be contained. Such a powder overlay material can be overlay welded to the press-molded surface of the die body by a general overlay welding means such as a powder plasma overlay welding method.

[Example] A test piece of a press-molding die was made of the material shown in Table 1, and a powder overlay material of an alloy component shown in Table 1 was formed on the surface of the test piece by a plasma overlay welding method. It was welded by overlay welding. Moreover, as shown in Table 1 as a dispersion strengthening material, they were appropriately added.

[0011]

[Table 1] The meanings of A to K in Table 1 are as follows. A: Cold die steel SKD1 (2C-13Cr) B: Hot die steel SKD61 (0.37C-5Cr) C: TiC (CVD) D: TiCN (PVD) E: NiCoCrAlY (32NI-38.4Co-2)
1Cr-8Al-0.6Y) F: NiCrAlY (67NI-22Cr-8Al-1)
Y) G: CoCrAlY (63Co-25Cr-10Al-
1Y) H: Y ₂ O ₃ I: Al ₂ O ₃ J: TiO ₂ K: Cr ₂ O ₃

The results of the MN test and the high temperature hardness (Hv) measurement at 700 ° C. of the test piece thus obtained are shown in Table 2. In the MN test, as shown in FIG. 1, a build-up raw material (Fe ₂ O ₃ ) was sprinkled between the two test pieces A and B subjected to plasma overlay welding and on the upper surface of the upper test piece A, The test piece was reciprocated while applying a load (8.5 kg) with a half-moon roll, and the test temperature was 850 ° C., test atmosphere air (78% N-20% O), and the test time was 4 hours. The build-up status of each side was evaluated. The evaluation criteria are as follows. ◎ ・ ・ ・ If you lay it down, the build-up raw materials will fall and there is no build-up. ○: Build-up material drops with compressed air of 6 kg / cm ² . X: The build-up raw material does not fall by the above means. In addition, FIG. 1 was provided in a heating furnace in which the atmosphere gas can be adjusted.

[0013]

[Table 2]

As is clear from the results of this test, all of the materials according to the present invention have a hardness (Hv) of 400 or more and are excellent in wear resistance, and are also excellent in build-up resistance. Moreover, no peeling of the welded part was observed, and it was confirmed that the mold can be continuously used for a long time as a press molding die. On the other hand, the same test was conducted using the one without overlay welding and the one with a ceramic sprayed coating as a comparative example, but the one without overlay welding had poor wear resistance and build-up resistance. Further, in the case where the ceramic sprayed coating was formed, the coating was immediately peeled off, and none of them could withstand continuous use for a long time.

[0015]

As is clear from the above description, the present invention is excellent in wear resistance and build-up resistance, can be continuously used for a long time, and can be used for warm press working. It can be continuously used without causing any trouble. Therefore, the present invention, as a press-molding die that eliminates the conventional problems, is extremely important in contributing to industrial development.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an MN test. (However, the heating and atmosphere gas control parts are excluded.)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C22C 19/05 C22C 19/05 B 19/07 19/07 G (72) Inventor Shinji Sato Tokai City, Aichi Prefecture Tokaicho 5-3 Nippon Steel Co., Ltd. Inside the Nagoya Works (72) Inventor Dosei Onishi 1 Toyota-cho, Toyota-shi, Aichi Prefecture F-term inside Toyota Motor Corporation (reference) 4E050 JA01 JB09 JC02 JD03

Claims (4)

[Claims] 1. A press forming surface of a die body made of an alloy tool steel comprises 15 to 40% by weight of Cr and 5 to 20% by weight of A.
1, 2% by weight or less of Y, and the balance of Ni and / or Co
A die for press molding, characterized in that a powder overlay material consisting of is overlay welded. 2. The alloy tool steel is SKD11 or SK.
The die for press molding according to claim 1, which is D61. 3. The press-molding die according to claim 1, wherein the powder facing material contains an oxide dispersant. 4. An oxide dispersant containing one or more of aluminum oxide, chromium oxide, titanium dioxide, silicon dioxide, zirconium oxide, magnesium oxide, yttrium oxide, and a rare earth oxide. The mold for press molding according to.