Moulding tool and method for powder injection moulding a cemented carbide or cermet component

Patent metadata

Field	Value
Publication number	US-10569332-B2
Application number	US-201615278771-A
Country	US
Kind code	B2
Filing date	Sep 28, 2016
Priority date	Sep 29, 2015
Publication date	Feb 25, 2020
Grant date	Feb 25, 2020

Abstract

A moulding tool for powder injection moulding a cemented carbide or cermet component includes a through hole. The moulding tool further includes at least a first and a second tool part arranged to define at least one mould cavity for forming a component. At least one inlet channel introduces moulding material into the mould cavity. The inlet channel extends through the first tool part to the mould cavity, and has an outlet end having an outlet opening for discharging moulding material from the inlet channel into the mould cavity. At least one core forms a through hole in the component, the core having an end and being arranged to extend into the mould cavity along a longitudinal axis (X) in a direction towards the outlet opening of the inlet channel. The end of the core is arranged to close the outlet opening of the inlet channel and the core is arranged movably along the longitudinal axis (X) such that the end of the core may engage with the outlet opening of the inlet channel.

First claim

The invention claimed is:

1. A moulding tool for powder injection moulding a cemented carbide or cermet component, said moulding tool comprising:
at least a first and a second tool part arranged to define at least one mould cavity for forming a component;
at least one inlet channel for introducing moulding material into the at least one mould cavity, said inlet channel extending through the first tool part to the mould cavity, the at least one inlet channel including an outlet end having an outlet opening for discharging moulding material from the inlet channel into the mould cavity;
at least one core forming a through hole in the component, said core being hollow and having an end and being arranged to extend into the mould cavity along a longitudinal axis in a direction towards the outlet opening of the inlet channel, the end of the core being arranged to close the outlet opening of the inlet channel, wherein the core is arranged to move along the longitudinal axis such that the end of the core engages with the outlet opening of the inlet channel, the core including means for holding a cold plug; and
an ejector pin slidably arranged in the core, wherein the ejector pin is positioned in the hollow core such that a space for receiving moulding material is delimited by the ejector pin and a wall of the hollow core.

2. The moulding tool according to claim 1 , wherein the end of the core is arranged to be inserted into the inlet channel through the outlet opening of the inlet channel.

3. The moulding tool according to claim 2 , wherein the end of the core and at least a contact section of the inlet channel have a cylindrical shape, wherein the outer diameter of the end of the core is dimensioned such that a longitudinal end portion of the core sealingly contacts the contact section of the inlet channel.

4. The moulding tool according to claim 1 , wherein an end surface of the core is arranged to abut against the outlet end of the inlet channel or against the first tool part.

5. The moulding tool according to claim 1 , wherein the at least a portion of the inlet channel has a tapered cross-section.

6. The moulding tool according to claim 1 , wherein the core is movable from a first position, in which the end of the core is at a predetermined distance from the outlet opening of the inlet channel, to a second position in which the end of the core closes the outlet opening of the inlet channel.

7. The moulding tool according to claim 6 , wherein the predetermined distance is selected such that a flow of moulding material entering the mould cavity impinges on the end of the core and is deflected in radial direction.

8. The moulding tool according to claim 1 , wherein the inlet channel extends into the mould cavity through the first tool part and the core is arranged to extend into the mould cavity through the second tool part, wherein tool parts are arranged opposing each other and wherein the core and the inlet channel each extend through the center of the respective first and second tool part.

9. The moulding tool according to claim 8 , wherein the core and the inlet channel are aligned such that the longitudinal axis extends through the center of the core and the center of the inlet channel.

10. A method for manufacturing a cemented carbide or cermet component having at least one through hole, the method comprising the steps of:
providing an injection moulding tool according to claim 1 ;
filling the mould cavity by introducing moulding material into the mould cavity through the outlet opening of the inlet channel;
moving the core to close the outlet opening of the inlet channel;
cooling the component for a predetermined cooling time;
opening the moulding tool;
removing the component from the moulding tool; and
sintering the component.

11. The method according to claim 10 , wherein the step of filling the mould cavity comprises the sub steps:
introducing moulding material into the mould cavity until a first predetermined pressure is reached in the mould cavity; and
pressurizing the mould cavity with moulding material at a second predetermined pressure, which is equal or lower than the first pressure until the outlet opening is closed.

12. The method according to claim 10 , further comprising prior to filling the mould cavity, positioning the ejector pin such that the core and the ejector pin delimits the space for the cold plug; and after opening the moulding tool, moving the ejector pin to eject the cold plug.

Assignees

• Sandvik Intellectual Property

Inventors

• Jansson Carl-Åke Gunnar

Classifications

• C22C29/04

  based on carbonitrides · CPC title

• C04B35/64

  Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F}) · CPC title

• C22C29/08

  based on tungsten carbide · CPC title

• B29K2103/00

  Use of resin-bonded materials as moulding material · CPC title

• B22F3/225 Primary

  by injection molding · CPC title