Method for forming molded article by press molding

Patent metadata

Field	Value
Publication number	US-10960633-B2
Application number	US-201615552654-A
Country	US
Kind code	B2
Filing date	Mar 18, 2016
Priority date	Mar 20, 2015
Publication date	Mar 30, 2021
Grant date	Mar 30, 2021

Abstract

Method of forming a compact based on the press forming method provides a compact having high density and not having cracking or surface roughness in a product and without compact adhesion to press forming mold wall occurring, including steps: filling raw material powder in a cavity formed by an outer mold and lower punch, or outer mold and lower punch and core rod, pressing and forming raw material powder between an outer punch and lower punch, and extracting the compact obtained out of the outer mold by the lower punch, wherein a lubricating film of a press forming mold lubricant containing oil as main component is formed on at least part of outer mold inner surface, or outer mold inner surface and core rod outer circumferential surface before filling the raw material powder in the cavity, and press forming so that compact density ratio is not less than 93%.

First claim

The invention claimed is:

1. A method of forming a compact based on a press forming method, comprising:
filling raw material powder in a cavity formed by:
an outer mold and a lower punch, or
an outer mold, a lower punch and a core rod,

pressing the raw material powder between an upper punch and the lower punch so as to form a compact, and
pressing the compact out of the outer mold,
wherein:
before the raw material powder is filled in the cavity, a lubricating film of a press forming mold lubricant is formed on at least a part of an inner surface of the outer mold, or an inner surface of the outer mold and an outer circumferential surface of the core rod,
the press forming mold lubricant consists of
an oil as a main component,
15 to 35 mass % of an extreme-pressure agent, based on a total amount of the press forming mold lubricant, and
10 to 20 mass % of a solid lubricant, based on the total amount of the press forming mold lubricant,

the press forming mold lubricant is formed by adding the solid lubricant and the extreme-pressure agent to a mineral oil, and
the press forming mold lubricant has a viscosity in a range of from 700 to 22000 mPa·s at 25° C., and
the raw material powder is pressed and formed into the compact so that a density ratio of the compact is not less than 93%.

2. The method of forming a compact based on a press forming method according to claim 1 , wherein:
the lower punch consists of multiple lower punches,
each surface of the multiple lower punches forms part of an outer circumference of the compact, and
the lubricating film of the press forming mold lubricant is formed on a part of the surface of at least one lower punch.

3. The method of forming a compact based on a press forming method according to claim 1 , wherein:
the upper punch consists of multiple upper punches,
each surface of the multiple upper punches forms part of an outer circumference of the compact, and
the lubricating film of the press forming mold lubricant is formed on a part of the surface of at least one upper punch.

4. The method of forming a compact based on a press forming method according to claim 1 , wherein a thickness of the lubricating film is from 5 to 40 μm.

5. The method of forming a compact based on a press forming method according to claim 1 , wherein the raw material powder contains an iron-based powder as a main component.

6. The method of forming a compact based on a press forming method according to claim 1 , wherein the solid lubricant contains at least one selected from the group consisting of graphite, a metal sulfide, a metallic soap, and a wax.

7. The method of forming a compact based on a press forming method according to claim 6 , wherein the solid lubricant contains graphite.

8. The method of forming a compact based on a press forming method according to claim 7 , wherein the graphite has an average particle diameter of from 1 to 50 μm.

9. The method of forming a compact based on a press forming method according to claim 1 , wherein the extreme-pressure agent is molybdenum dialkyldithiophosphate.

10. The method of forming a compact based on a press forming method according to claim 1 , wherein:
the filling of the raw material powder in a cavity includes absorption of a part of the press forming mold lubricant in gaps among the raw material powder by capillary action, and
the pressing of the raw material powder so as to form the compact includes squeezing the absorbed press forming mold lubricant from the gaps among the raw material powder to between the compact and the wall of the mold by the pressing force.

11. The method of forming a compact based on a press forming method according to claim 1 , wherein the raw material powder filled in a cavity formed by an outer mold, a lower punch and a core rod.

Assignees

• Hitachi Chemical Co Ltd

Inventors

• Onodera Satoshi
• Ueda Katsuhiko
• Kohida Tomoyuki
• Ichikawa Junichi

Classifications

• B30B15/0011 Primary

  lubricating means · CPC title

• C10M171/02

  Specified values of viscosity or viscosity index · CPC title

• B30B11/00

  Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses (for clay or mixtures containing cement B28B; for plastics materials B29) · CPC title

• B22F2003/026

  Mold wall lubrication or article surface lubrication · CPC title

• B30B11/02

  using a ram exerting pressure on the material in a moulding space · CPC title