Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

MOLD FOR HOT-FORMING Zn-PLATED STEEL SHEET

a technology of zn-plated steel and hot-forming tool, which is applied in the direction of manufacturing tools, shaping tools, vacuum evaporation coating, etc., can solve the problems of hot pressing method, zn softening, product shape and surface quality of formed steel sheets, etc., to inhibit zn adhesion, reduce zn reactivity, and reduce zn reactivity

Inactive Publication Date: 2017-02-09
KOBE STEEL LTD
View PDF2 Cites 11 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a forming tool that can prevent Zn adhesion during the hot forming of Zn-plated steel sheets. This is achieved by controlling the surface profile of the coating film in contact with the Zn-plated steel sheet. The coating film should have a roughness of 2.0 μm or less, preferably 1.0 μm or less, to inhibit Zn adhesion. Additionally, the root-mean-square slope of the surface should also be regulated to further prevent Zn adhesion. The inventor has discovered that amorphous-carbon coating films with a hydrogen content of 25 atom % or less are suitable for reducing reactivity with Zn and preventing adhesion.

Problems solved by technology

The hot pressing method has problems such as the following.
However, since the melting point of Zn is lower than the heating temperature of the steel sheet, the Zn softens during the high-temperature forming.
In the case where this adhesion of Zn is serious, the shape of the forming tool is changed, arousing problems concerning product shape and the surface quality of the formed steel sheet.
However, the ceramic coating film is not considered to be sufficient for inhibiting the Zn adhesion to the forming tools.
However, in the case of Zn, which becomes soft at a lower temperature than the magnesium, only the means of Patent Document 1 and Patent Document 2 cannot sufficiently inhibit adhesion to the forming tool.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0046]In Example 1, the influences of the composition and hydrogen content of a coating film on Zn adhesion resistance were examined. Hereinafter, a coating film formed on a substrate surface is often referred to as a coating.

[0047]A mirror-surface substrate constituted of SKD11 and having an HRC of 60 and a substrate Ra of 0.005 μm was prepared as a substrate for evaluating the surface profile of a coating. Meanwhile, a mirror-surface bending tool constituted of SKD61 and having a substrate Ra of 0.01 to 3 μm was prepared for evaluating Zn adhesion resistance. As a coating, each of coating films of nitrides, i.e., TiN, CrN and TiAlN, as conventional coating films, DLC films having the hydrogen contents shown in Table 1, and the DLC films containing Si or W as shown in Table 1 was formed on a surface of the substrate.

[0048]These coatings were formed by the un-balanced magnetron sputtering method. The film deposition conditions for the un-balanced magnetron sputtering method included...

example 2

[0061]In Example 2, the influence of the surface profile of a DLC film on Zn adhesion resistance was examined.

[0062]Samples were produced in the same manner as in Example 1, except that a substrate was coated with a DLC film having a hydrogen content of 10 atom % and the Ra, RΔq and Rsk were changed as shown in Table 2. In Example 1 and Example 3, which will be given layer, a substrate having a mirror surface was used. In this Example 2, however, the roughness of the substrate was varied by the method described above, and a DLC film was formed thereon. Thus, samples which varied in the Ra, RΔq and Rsk were prepared.

[0063]A Zn adhesion evaluation test was conducted in the same manner as in Example 1 to evaluate Zn adhesion resistance. The results thereof are shown in Table 2.

TABLE 2Evaluationof ZnRaRΔqRskadhesionNo.(μm)(°)(−)resistance10.010.01−2.0020.10.03−2.0030.50.05−1.0041.00.10−0.5152.00.30−0.2163.00.40−0.2372.00.60−0.1382.00.70−0.1392.00.300.52

[0064]The following can be seen fr...

example 3

[0065]In Example 3, the influence of the proportion of sp2 bonds in a DLC film on Zn adhesion resistance was examined.

[0066]Samples were produced in the same manner as in Example 1, except that one of the coating films was formed by the arc ion plating (AIP) method and that the voltage which was applied to the substrate during film deposition by the AIP method or UBMS method was changed to thereby form DLC films differing in the proportion of sp2 bonds as shown in Table 3. The hydrogen content was regulated in the same manner as in Example 1. The film deposition conditions for the arc ion plating method included a substrate temperature of 400° C., a total gas pressure of 4 Pa and a bias voltage of −50 V. A Zn adhesion evaluation test was conducted in the same manner as in Example 1 to evaluate Zn adhesion resistance.

[0067]The proportion of sp2 bonds was ascertained by EELS analysis. The measurement conditions for the EELS analysis are as follows.

EELS analysis apparatus: Tridiem, man...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
temperatureaaaaaaaaaa
surface roughnessaaaaaaaaaa
surface roughnessaaaaaaaaaa
Login to View More

Abstract

A forming tool for use in a hot forming of a Zn-plated steel sheet is provided. At least a portion of the forming tool to be in contact with the Zn-plated steel sheet during the hot forming is covered with an amorphous-carbon coating film. The amorphous-carbon coating film satisfies the following conditions (1) to (4): (1) a film thickness is 0.5 μm or larger; (2) a surface has an arithmetic mean roughness Ra of 2.0 μm or less; (3) the surface has a root-mean-square slope RΔq of 0.50° or less; and (4) a hydrogen content is 30 atom % or less.

Description

TECHNICAL FIELD[0001]The present invention relates to a forming tool for hot forming of Zn-plated steel sheets. The present invention particularly relates to a forming tool which is used in performing a hot pressing, after a Zn-plated steel sheet is heated at a high temperature in the austenite range. The hot pressing is referred to also as hot stamping, die quenching, press quenching, or hot pressing.BACKGROUND ART[0002]The hot pressing method has problems such as the following. The hot pressing method is a technique in which a blank that is a steel sheet is heated usually to a temperature range of austenite of 800 to 900° C. and then rapidly cooled and simultaneously formed into a desired part shape by means of a water-cooled forming tool. The steps from the heating of the steel sheet to the pressing are conducted in the air from the standpoint of cost. Consequently, for the purpose of inhibiting scale formation due to steel sheet oxidation, a Zn-plated steel sheet which has a pla...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(United States)
IPC IPC(8): B21D37/01B21D24/00B21D22/20
CPCB21D37/01B21D24/00B21D22/20C23C14/0605C23C14/024C23C14/0057C23C14/34
Inventor YAMAMOTO, KENJI
Owner KOBE STEEL LTD
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com