SINTERING METHOD AND APPARATUS

• US 20120329659A1
• Filed: 06/25/2012
• Published: 12/27/2012
• Est. Priority Date: 06/23/2011
• Status: Active Grant

• Current Assignee: Grid Logic Incorporated
• Original Assignee: Grid Logic Incorporated
• Inventors: Holcomb, Matthew J.
• Granted Patent: US 9,457,403 B2
• Time in Patent Office: Days
• US Class Current: 505/400
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/32 of the atmosphere, e.g. composition or pressure in a building chamber
• CPC Class Codes: B22F 12/13 to preheat the material
• CPC Class Codes: B22F 7/06 of composite workpieces or articles from parts, e.g. to form tipped tools B22F7/002 takes precedence
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: H05B 6/10 Induction heating apparatus, other than furnaces, for specific applications
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

A sintering apparatus comprising a container for holding small particles that contact one another, an electric current generator generating an alternating electric current and a flux concentrator having a collector positioned to be exposed to an alternating magnetic field generated by the alternating electric current and a tip that focuses the alternating magnetic field so that the particles are exposed to the alternating magnetic field, the alternating magnetic field heating surfaces of the particles so that they join and are fused together.

Claims

1. A method of sintering small particles, comprising:

holding the particles in contact with one another;

generating an alternating electric current; and

exposing the particles to an alternating magnetic field generated by the alternating magnetic current so that they heat and join.

2. The method of claim 1, further comprising:

exposing a collector of a flux concentrator to the alternating magnetic field generated by the alternating electric current; and

focusing the alternating magnetic field with a tip of the flux concentrator so that the particles are exposed to the alternating magnetic field.

3. The method of claim 1, wherein each particle has a cross-dimension that is more than 2δ

and δ

is defined as

4. The method of claim 1, wherein the alternating magnetic field has a frequency of at least 100 kHz.

5. The method of claim 3, wherein the frequency is at least 2 MHz.

6. The method of claim 1, wherein the particles are exposed to two different frequencies that cause joining of two different parts of the particles.

7. The method of claim 6, wherein a high-frequency heats smaller parts and a low frequency heats larger parts.

8. The method of claim 7, wherein the two frequencies occur simultaneously.

9. The method of claim 6, wherein the two frequencies occur at different times to heat different types of parts.

10. The method of claim 1, wherein the surfaces heat to above 90% of a melting temperature of the particles in Kelvin.

11. The method of claim 1, wherein the particles include ceramic material.

12. The method of claim 1, wherein the particles include superconductor material.

13. A sintering apparatus comprising:

a container for holding small particles that contact one another;

an electric current generator generating an alternating electric current; and

a flux concentrator having a collector positioned to be exposed to an alternating magnetic field generated by the alternating electric current and a tip that focuses the alternating magnetic field so that the particles are exposed to the alternating magnetic field, the alternating magnetic field heating at least surfaces of the particles so that they join.

14. The sintering apparatus of claim 13, wherein the tip focuses the magnetic field so that a portion of the particles in the container are exposed to the magnetic field.

15. The sintering apparatus of claim 14, further comprising:

a frame;

a component movably mounted to the frame;

an actuator connected between the frame and the component to move the component relative to the frame, movement of the component relative to the frame causing movement of the flux concentrator relative to the particles so that the magnetic field is reduced from a first portion of the particles that has been joined to allow the first portion to cool while exposing a second adjacent portion of the particles to the magnetic field.

16. The sintering apparatus of claim 15, wherein the flux concentrator is mounted to the component so as to move together with the component.

17. The sintering apparatus of claim 15, further comprising:

a processor;

a computer-readable medium connected to the processor; and

a set of instructions on the computer-readable medium that are executable by the processor;

including;

a CNC module that actuates the actuator to cause at least two-dimensional movement.

18. The sintering apparatus of claim 13, further comprising:

a processor;

a computer-readable medium connected to the processor; and

a set of instructions on the computer-readable medium that are executable by the processor;

including;

at least on selectable recipe for selecting a frequency of the alternating magnetic field, wherein each particle has a cross-dimension that is more than 2δ and

δ

is defined as

19. The sintering apparatus of claim 18, wherein the instructions include:

a recipe data store holding a plurality of recipes; and

a recipe selector operable to select one of the recipes.

20. The sintering apparatus of claim 18, wherein the instructions further include:

a frequency modulation module that utilizes the frequency in the recipe to modulate a frequency of the alternating electric current.

21. A method of sintering, comprising:

holding small particles and a part in contact with one another;

pre-heating the part by generating an alternating electric current and exposing the part to an alternating magnetic field generated by the alternating electric current; and

heating only a portion of the particles that are in contact with the part so that the particles of the portion join with the part.

22. The method of claim 21 wherein the alternating electric current for pre-heating the part is a low frequency alternating electric current and the particles are heated by:

generating a high frequency alternating electric current; and

exposing the particles to an alternating magnetic field generated by the high frequency alternating electric current.

23. A sintering apparatus comprising:

a container for holding small particles and a part that contact one another;

a pre-heater that includes an electric current generator generating an alternating electric current, and a coil generating an alternating magnetic field generated so that the part is exposed to the alternating magnetic field of the coil, the alternating magnetic field heating the part; and

a localized heater heating only a portion of the so that the particles of the portion join with the part.