Method and apparatus for producing parts by selective sintering

• US 5,017,753 A
• Filed: 06/22/1990
• Issued: 05/21/1991
• Est. Priority Date: 10/17/1986
• Status: Expired due to Term

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Deckard, Carl R.
• Primary Examiner(s): ALBRITTON, CLARENCE
• Application Number:
  US07/545,142
• Time in Patent Office: 333 Days
• Field of Search: 219/121.63, 219/121.64, 219/121.65, 219/121.66, 219/121.6, 219/121.85, 219/121.12, 219/121.35, 219/121.14, 219/121.13, 219/121.21
• US Class Current: 264/497
• CPC Class Codes: B05C 19/00 Apparatus specially adapted for applying particulate materials to surfaces
• CPC Class Codes: B05C 19/008 Accessories or implements for use in connection with applying particulate materials to surfaces; not provided elsewhere in B05C19/00
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/366 Scanning parameters, e.g. hatch distance or scanning strategy
• CPC Class Codes: B22F 10/80 Data acquisition or data processing
• CPC Class Codes: B22F 12/10 Auxiliary heating means
• CPC Class Codes: B22F 12/41 characterised by the type, e.g. laser or electron beam
• CPC Class Codes: B22F 12/44 characterised by the configuration of the radiation means
• CPC Class Codes: B22F 12/49 Scanners
• CPC Class Codes: B22F 12/52 Hoppers
• CPC Class Codes: B22F 12/57 Metering means
• CPC Class Codes: B22F 12/63 Rollers
• CPC Class Codes: B22F 12/70 Gas flow means
• CPC Class Codes: B22F 2003/1052 assisted by energy absorption enhanced by the coating or powder
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 3/004 Filling molds with powder feeding material to presses in general B30B15/302
• CPC Class Codes: B22F 3/105 by using electric current other than for infrared radiant energy, laser radiation or plasma B22F3/11 takes precedence; by ultrasonic bonding B22F3/115 takes precedence
• CPC Class Codes: B22F 3/26 Impregnating making ferrous alloys by impregnation C22C33/0242
• CPC Class Codes: B22F 7/02 of composite layers B22F7/002 takes precedence
• CPC Class Codes: B23K 26/08 : Devices involving relative movement between laser beam and workpiece
• CPC Class Codes: B23K 26/082 : Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/34 : Laser welding for purposes other than joining
• CPC Class Codes: B29C 35/045 : using gas or flames
• CPC Class Codes: B29C 41/12 : Spreading-out the material on a substrate , e.g. on the surface of a liquid
• CPC Class Codes: B29C 41/46 : Heating or cooling
• CPC Class Codes: B29C 64/153 : using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: C23C 24/08 : by application of heat or pressure and heat C23C24/04 takes precedence
• CPC Class Codes: C23C 24/10 : with intermediate formation of a liquid phase in the layer
• CPC Class Codes: C23C 26/02 : applying molten material to the substrate
• CPC Class Codes: G05B 19/41 : characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path G05B19/25, G05B19/31, G05B19/37, G05B19/39, G05B19/40 take precedence
• CPC Class Codes: G05B 2219/49013 : Deposit layers, cured by scanning laser, stereo lithography SLA, prototyping
• CPC Class Codes: G05B 2219/49018 : Laser sintering of powder in layers, selective laser sintering SLS
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Preferably, the powder dispensing mechanism includes a drum which is moved horizontally across the target area and counter-rotated to smooth and distribute the powder in an even layer across the target area. A downdraft system provides controlled temperature air flow through the target area to moderate powder temperature during sintering.

Claims

1. An apparatus for producing a part comprising:

beam means for selectively emitting a directed energy beam;

structure for providing a target area for producing the part;

means for dispensing powder into said target area including,

a drum,

means for moving the drum from one end of the target area to the other end, and

means for counter-rotating the drum;

means for directing air flow through the target area to moderate powder temperature; and

control means for moving the aim of the beam and for modulating the beam means to selectively sinter within defined boundaries a layer of powder dispensed in said target area,

the control means being operable to effect selective sintering of sequential layers of powder within respective defined boundaries to produce a part comprising a plurality of layers sintered together.

2. A method of producing a part comprising the steps of:

depositing a first portion of powder onto a target surface, including the substeps of--

depositing a mound of powder proximate one end of the target surface,

moving a counter-rotating drum from said one end of the target surface in the direction of another end to contact the mound and leave a layer of powder between the drum and said one end;

scanning the aim of a directed energy beam over the target surface;

sintering a first layer of the first powder portion corresponding to a first cross-sectional region of the part by operating the beam when the aim of the beam is within boundaries defined by said first cross-sectional region;

inducing air flow to the target surface to moderate the temperature of the sintered and unsintered powder deposited thereon;

depositing a second portion of powder onto the first sintered layer;

scanning the aim of a directed energy beam over the first sintered layer;

sintering a second layer of the second powder portion corresponding to a second cross-sectional region of the part by operating the beam when the aim of the beam is within boundaries defined by said second cross-sectional region,

the first and second layers being joined during the sintering of said second layer; and

depositing successive portions of powder onto the previous sintered layers and sintering a layer of each successive portion to produce a part comprising a plurality of sintered layers.

3. An apparatus for moderating temperature of a powder being sintered in a target area, comprising:

a support defining the target area and including a medium porous to air and a plenum for directing air passing through the medium away from the target area;

means for dispensing powder into the target area;

means for selectively sintering powder in the target area;

means for directing air to the target area; and

means for controlling the temperature of the air prior to reaching the target area.

4. The apparatus in accordance with claim 3, wherein said directing means comprises a chamber surrounding said target area and a blower fan impelling air into the chamber.

5. The apparatus in accordance with claim 3, said selective sintering means comprising a directed energy beam and means for controlling the aim of the beam and for modulating the beam.

6. The apparatus in accordance with claim 3, said dispensing means comprising a drum, means for moving the drum from one end of the target area to the other end, means for counter-rotating the drum, and means for depositing a mound of powder proximate said one end.

7. The apparatus in accordance with claim 3, said temperature controlling means comprising a heating element disposed in the air.