Method for producing a green compact using a pressing tool, a pressing tool, a green compact, and a sintered part

Patent metadata

Field	Value
Publication number	US-11318533-B2
Application number	US-201816494554-A
Country	US
Kind code	B2
Filing date	Mar 14, 2018
Priority date	Mar 14, 2017
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

A method for producing a green compact uses a pressing tool including a die, a first punch to be displaced in an axial direction, a second punch to be displaced in a radial direction through a channel in the die and a receptacle having a filling opening. The method includes locating the second punch before or during filling of a powdery material into the receptacle so as to be outwardly offset in the radial direction relative to an inner peripheral surface, filling the powdery material into the receptacle, and moving at least the first punch and the second punch and compressing the material in the receptacle, with the second punch being moved in the radial direction toward the receptacle only so far that it is disposed flush with a region of the inner peripheral surface. A pressing tool, a green compact and a sintered part are also provided.

First claim

The invention claimed is:

1. A green compact produced by compression of a powdery material, the green compact comprising:
a first end and a second end defining an axial direction therebetween;
a longitudinal axis extending along said axial direction;
a wall region extending parallel to said longitudinal axis and along said axial direction from said first end to said second end;
said wall region including a subregion spaced apart from said first end and said second end;
said wall region having a compressed first surface texture outside said subregion; and
said subregion having a second surface texture being different from said first surface texture;
wherein said subregion has no undercuts to said wall region and ends flush with said wall region or is offset into the green compact by no more than 0.1 mm relative to said wall region in a radial direction.

2. The green compact according to claim 1 , which further comprises first and second parting lines disposed between said subregion and said wall region, said subregion extending along said axial direction between said first and second parting lines, and said first and second parting lines forming a transition from said first surface texture to said second surface texture.

3. The green compact according to claim 2 , wherein at least one of said parting lines has a curved shape.

4. The green compact according to claim 1 , which further comprises a portion tapering along said axial direction, said portion having a largest cross section and a smallest cross section transverse to said axial direction, said portion having a ratio between said largest cross section and said smallest cross section of at least 2:1, and said subregion being disposed on said portion.

5. A sintered part, comprising:
a heat-treated green compact according to claim 1 ;
said heat-treated green compact having a third surface texture disposed in a region of said first surface texture; and
said heat-treated green compact having a fourth surface texture in a region of said second surface texture.

6. A method for producing the green compact according to claim 1 , the method comprising the following steps:
providing a pressing tool including at least one die extending along the axial direction between a first end face and a second end face of the at least one die and forming an inner peripheral surface of the at least one die with an opening between the end faces, the inner peripheral surface forming a receptacle for the green compact, at least one first punch being movable along the axial direction from one of the end faces of the die into the receptacle, and at least one second punch being movable along a radial direction through a channel in the die toward the receptacle, the inner peripheral surface having a region disposed along the axial direction between the one end face, from which the first punch is movable, and the opening;
a) placing the second punch outwardly offset in the radial direction relative to the inner peripheral surface before or during step b);
b) filling a powdery material into the receptacle; and
c) moving at least the first punch and the second punch and compressing the material in the receptacle, the second punch being moved in the radial direction toward the receptacle only far enough to be disposed flush with or to protrude into the receptacle by no more than 0.1 mm at least relative to the region of the inner peripheral surface in the radial direction.

7. The method according to claim 6 , which further comprises placing the second punch offset in step a) or during step b) so far in the radial direction relative to the inner peripheral surface that the material filled in step b) is also disposed in the channel.

8. The method according to claim 7 , which further comprises displacing the material disposed in the channel through the opening into the receptacle as a result of the movement of the second punch in step c).

9. The method according to claim 6 , which further comprises providing the second punch with at least one first punch part and at least one second punch part being movable independently of one another.

10. The method according to claim 9 , which further comprises placing the punch parts next to one another along the axial direction.

11. The method according to claim 6 , which further comprises using the second punch to compact said subregion of said wall region of the green compact extending along the axial direction from said first end to said second end of the wall region in step c), the subregion being spaced apart at least from the first end or from the second end.

12. The method according to claim 6 , which further comprises placing the second punch on a portion of the green compact that tapers along the axial direction, and providing a ratio of at least 2:1 between a largest cross section and a smallest cross section of the portion transverse to the axial direction.

13. A green compact produced by compression of a powdery material, the green compact comprising:
a first end and a second end defining an axial direction therebetween;
a longitudinal axis extending along said axial direction;
a wall region extending parallel to said longitudinal axis and along said axial direction from said first end to said second end;
said wall region including a subregion spaced apart from said first end and said second end;
said wall region having a compressed first surface texture outside said subregion;
said subregion having a second surface texture being different from said first surface texture; and
first and second parting lines disposed between said subregion and said wall region, said subregion extending along said axial direction between said first and second parting lines, and said first and second parting lines forming a transition from said first surface texture to said second surface texture;
wherein at least one of said parting lines has a curved shape.

14. A sintered part, comprising:
a heat-treated green compact according to claim 13 ;
said heat-treated green compact having a third surface texture disposed in a region of said first surface texture; and
said heat-treated green compact having a fourth surface texture in a region of said second surface texture.

15. A green compact produced by compression of a powdery material, the green compact comprising:
a first end and a second end defining an axial direction therebetween;
a longitudinal axis extending along said axial direction;
a wall region extending parallel to said longitudinal axis and along said axial direction from said first end to said second end;
said wall region including a subregion spaced apart from said first end and said second end;
said wall region having a compressed first surface texture outside said subregion; and
said subregion having a second surface texture being different from said first surface texture;
a portion tapering along said axial direction, said portion having a largest cross section and a smallest cross section transverse to said axial direction, said portion having a ratio between said largest cross section and said smallest cross section of at least 2:1, and said subregion being disposed on said portion.

16. A sintered part, comprising:
a heat-treated green compact according to claim 15 ;
said heat-treated green compact having a third surface texture disposed in a region of said first surface texture; and
said heat-treated green compact having a fourth surface texture in a region of said second surface texture.

Assignees

• Gkn Sinter Metals Engineering Gmbh

Inventors

• Tiller Stefan
• Schmitt Rainer
• Bornemann Nils

Classifications

• B28B3/086

  The rams working in different directions · CPC title

• B30B11/007

  using a plurality of pressing members working in different directions · CPC title

• B22F3/03 Primary

  Press-moulding apparatus therefor · CPC title

• B30B15/022

  Moulds for compacting material in powder, granular of pasta form · CPC title

• B22F3/02 Primary

  Compacting only · CPC title