# US 2021/0331384 A1 · Fusing three-dimensional (3d) object layers

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- Number: US 2021/0331384 A1
- Document ID: US20210331384A1
- Status: Published application
- Kind: A1
- Application number: 16/608,923
- Filed: 2018-07-31
- Published: 2021-10-28
- Earliest claimed: 2018-07-31
- Assignees: Hewlett-Packard Development Company, L.P.
- Applicants: Hewlett-Packard Development Company, L.P.
- Inventors: Alvin Post; Brent Ewald
- Web page: https://patentgrep.com/patent/US20210331384A1

## CPC

- B29C 64/165: using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber
- B29C 64/209: Heads; Nozzles
- B29C 64/218: Rollers
- B29C 64/232: for motion along the axis orthogonal to the plane of a layer
- B29C 64/236: for motion in a direction within the plane of a layer
- B29C 64/268: using laser beams; using electron beams [EB]
- B29C 64/282: of the same type, e.g. using different energy levels
- B33Y 10/00: Processes of additive manufacturing
- B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING

## Abstract

In an example implementation, a method of fusing a 3D object layer includes, with a non-scanning, stationary energy system positioned over a work area, simultaneously irradiating the entirety of the work area uniformly with fusing light, wherein a carriage casts a shadow onto a portion of the work area and prevents fusing light from irradiating the portion of the work area when positioned between the fusing light and the work area. The method includes, with a first pass of the carriage from a first side to a second side of the work area, spreading a first layer of build material and dispensing a liquid fusing agent onto the first layer such that exposure time to the fusing light is unequal across the first layer, and with a second pass, returning the carriage to the first side. The method includes spreading a next layer of build material and dispensing a liquid fusing agent onto the next layer with a third pass of the carriage from the first side to the second side, such that the exposure time to the fusing light is made equal across the first layer.

## Claims

### Claim 1

A method of fusing a 3D object layer comprising:
with a non-scanning, stationary energy system positioned over a work area, simultaneously irradiating the entirety of the work area uniformly with fusing light, wherein a carriage casts a shadow onto a portion of the work area and prevents fusing light from irradiating the portion of the work area when positioned between the fusing light and the work area;
with a first pass of the carriage from a first side to a second side of the work area, spreading a first layer of build material and dispensing a liquid fusing agent onto the first layer such that exposure time to the fusing light is unequal across the first layer;
with a second pass, returning the carriage to the first side;
with a third pass of the carriage from the first side to the second side, spreading a next layer of build material and dispensing a liquid fusing agent onto the next layer such that the exposure time to the fusing light is made equal across the first layer.

### Claim 2 (depends on 1)

A method as in claim 1, further comprising:
prior to the first pass, deploying a roller from the carriage, the roller contacting the build material and spreading it into the first layer during the first pass.

### Claim 3 (depends on 1)

A method as in claim 1, further comprising:
parking the carriage on the second side for a delay period to increase the exposure time to the fusing light across the first layer.

### Claim 4 (depends on 1)

A method as in claim 1, further comprising:
after the first pass and before the second pass, retracting the roller on the carriage so that the roller does not contact the build material during the second pass.

### Claim 5 (depends on 1)

A method as in claim 1, further comprising:
after the second pass and before the third pass, deploying the roller on the carriage so that the roller contacts build material and spreads it into the next layer during the third pass.

### Claim 6 (depends on 2)

A method as in claim 2, wherein the carriage moves at a speed that is substantially the same in the first pass and the third pass.

### Claim 7

A method of fusing a 3D object layer comprising:
spreading a layer of build material onto a work area with two passes of a spreading roller, a first pass moving the roller from a first side to a second side of the work area, and a second pass moving the roller back to the second side;
dispensing a liquid fusing agent onto the layer from a dispenser in a third pass that moves the roller and the dispenser together from the first side to the second side;
returning the roller and dispenser to the first side in a fourth pass; and,
continually irradiating the whole work area simultaneously and uniformly with fusing light except when the roller or dispenser pass over the work area and block the fusing light from reaching the work area.

### Claim 8 (depends on 7)

A method as in claim 7, further comprising:
wherein the roller is carried on a first carriage, deploying the roller on the first carriage prior to the first pass such that the roller contacts the build material on the first and second passes; and,
retracting the roller on the first carriage after the second pass and before the third pass such that the roller does not contact the build material on the third and fourth passes.

### Claim 9 (depends on 8)

A method as in claim 8, further comprising:
wherein the dispenser is carried on a second carriage, leaving the second carriage parked on the first side of the work area during the first and second passes.

### Claim 10 (depends on 7)

A method as in claim 7, further comprising:
parking the roller for a warming delay period on the second side after the first pass or on the first side after the second pass to provide additional time for fusing light to warm the layer of build material.

### Claim 11 (depends on 7)

A method as in claim 7, further comprising:
after the fourth pass, parking the roller and dispenser on the first side for a fusing delay period to provide additional time for fusing light to fuse areas of the layer of build material where liquid fusing agent has been dispensed.

### Claim 12 (depends on 11)

A method as in claim 11, wherein parking the roller and dispenser on the first side comprises parking the roller and dispenser on a pen servicing side of the work area with the roller positioned between the work area and the dispenser.

### Claim 13

A method of fusing with a stationary lighting assembly, comprising:
spreading a first layer of powdered build material onto a platform in a first pass of a roller over the platform from a first side to a second side of the platform;
spreading the first layer a second time in a second pass that moves the roller and a dispenser over the platform from the second side to the first side;
parking the roller adjacent to the first side, and selectively dispensing a liquid fusing agent onto the first layer in a third pass that moves the dispenser from the first side to the second side;
parking the dispenser adjacent to the second side, and spreading a next layer of powdered build material over the first layer; and,
simultaneously and continuously irradiating the entire platform with fusing energy from a stationary lighting assembly such that the entire first layer receives a uniform amount of fusing energy.

### Claim 14 (depends on 13)

A method as in claim 13, wherein selectively dispensing a liquid fusing agent onto the first layer happens during the second pass and the dispenser is returned to the second side during the third pass.

### Claim 15 (depends on 13)

A method as in claim 13, further comprising:
after the third pass, leaving the roller parked adjacent to the first side and parking the dispenser adjacent to the second side during a fusing delay period to provide additional time for fusing energy to fuse areas of build material patterned with liquid fusing agent.