Layer transfusion with transfixing for additive manufacturing

Patent metadata

Field	Value
Publication number	US-9904223-B2
Application number	US-201213624507-A
Country	US
Kind code	B2
Filing date	Sep 21, 2012
Priority date	Sep 23, 2011
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

An additive manufacturing system comprising a transfer medium configured to receive the layers from a imaging engine, a heater configured to heat the layers on the transfer medium, and a layer transfusion assembly that includes a build platform, and is configured to transfuse the heated layers onto the build platform in a layer-by-layer manner to print a three-dimensional part.

First claim

The invention claimed is:

1. An additive manufacturing system for printing a three-dimensional thermoplastic part, the additive manufacturing system comprising:
an imaging engine configured to develop imaged layers of a thermoplastic-based powder;
at least two rollers, wherein each roller is positioned in a fixed position and rotatable about an axis of rotation, wherein at least a first roller comprises a nip roller and a second roller comprises a release roller spaced a first distance from the nip roller, wherein the fixed positions of the nip roller and the release roller are proximate a build plane wherein the nip roller and the release roller define a path of travel of a belt proximate the build plane and wherein the travel path descends in a rotational direction toward the build plane proximate the nip roller and ascends in a rotational direction away from the build plane proximate the release roller,
the rotatable belt having a front side and a back side, the front side configured to receive a developed layer of a themoplastic-based powder and the back side configured to engage the at least two rollers wherein the developed layer has a leading edge and a trailing edge and a width defined by first and second side surfaces;
a build platform configured to move and receive the imaged layers from the belt in a layer-by-layer manner to print the three-dimensional part on the build platform;
a gantry configured to move the build platfoiiu in a reciprocating pattern such that a top surface of the three-dimensional part being formed on the build platform travels within the build plane and out of the build plane, the movement being synchronized with the rotational rate of the belt wherein the gantry is configured to move the top surface of the three-dimensional part being formed in the build plane a second distance from a first build plane location to a second build plane location wherein the second distance is longer than the first distance, wherein the first build plane location is located a third distance in an upstream direction of the nip roller such that the three-dimensional part being formed on the build platform is not in contact with the imaged layer or the belt at the first build plane location, and the leading edge of the imaged layer is configured to register with a front location of the build platform at the nip roller as the top surface of the three-dimensional part being formed moves in the build plane such that the imaged layer is transferred to the previously printed layer in a line by line manner across the width of the imaged layer utilizing pressure and heat as the nip roller rotates and the build platform is moved from the first build location to the second build location, and wherein the second build plane location is located a distance from the release roller such that the trailing edge is configured to disengage the belt as the top surface of the three-dimensional part being formed moves in the build plane;
a cooling unit positioned between the nip roller and the release roller, the cooling unit configured to actively cool the imaged layers while it remains on the belt.

2. The additive manufacturing system of claim 1 , wherein the travel path of the rotatable belt moves the belt from the imagine engine, in between the nip roller and build platform, past the cooling unit and around the release roller.

3. The additive manufacturing system of claim 1 , and further comprising a first heater configured to heat the imaged layer on the belt.

4. The additive manufacturing system of claim 1 and further comprising:
a pressure sensor in communication with the movable build platform and configured to sense the pressure between the nip roller and the movable build platform wherein the sensor is configured to transmit a signal indicative of the sensed pressure; and
a controller configured to receive the signal from the pressure sensor and to send a signal to the movable build platform based upon the received signal from the pressure sensor to adjust the pressure between the nip roller and the movable build platform on a subsequent transfusion of an imaged layer.

5. The additive manufacturing system of claim 4 and further comprising:
a height sensor configured to measure a height of the three-dimensional part and to transmit a signal indicative of the sensed height of the three-dimensional part; and
the controller is configured to receive the signal from the height sensor and to send a signal to the movable build platform based upon the received signal from the height sensor to adjust the pressure between the nip roller and the movable build platform on a subsequent transfusion of an imaged layer.

6. The additive manufacturing system of claim 1 , wherein the imaging engine comprises an electrophotography engine which is configured to develop the imaged layers from the thermoplastic-based powder.

7. The additive manufacturing system of claim 1 , wherein the belt comprises a multiple-layer belt.

8. The additive manufacturing system of claim 1 , wherein the gantry is configured to move the build platform in a reciprocating rectangular pattern.

9. The additive manufacturing system of claim 1 , and further comprising a second heater configured to heat a surface of the three-dimensional part prior to engaging the nip roller.

10. The additive manufacturing system of claim 1 , and further comprising a second cooling unit located downstream from the release roller, the cooling unit configured to actively cool the top surface of the three dimensional part to hold the printed three-dimensional part at about an average part temperature that is below a deformation temperature of the three-dimensional part.

11. The additive manufacturing system of claim 1 , wherein the nip roller comprises a heatable roller.

12. An additive manufacturing system for printing a three-dimensional thermoplastic part, the additive manufacturing system comprising:
an imaging engine configured to develop imaged layers of a thermoplastic-based powder;
at least three rollers, wherein each roller is positioned in a fixed position and rotatable about an axis of rotation, wherein at least a first roller comprises a nip roller wherein the fixed position of the nip roller is proximate a build plane and wherein the fixed position of at least a second roller of the at least three rollers is located a distance from the build plane;
a rotatable belt having a first surface and a second surface, the rotatable belt configured to receive imaged layers of a thermoplastic-based powder on the first surface, each imaged layer having a length from a leading edge to a trailing edge and a width from a first side to a second side, wherein the second surface of the belt is configured to engage the at least three rollers and wherein the at least three rollers define a path of travel of the belt wherein the travel path of the belt proximate the build plane follows a first distance between a transfer engaging location at the nip roller and a transfer disengaging location, and the travel path descends in a rotational direction toward the nip roller and ascends in a rotational direction away from the build plane proximate the transfer disengaging location;
a build platform configured to move and receive the imaged layers from the belt in a layer-by-layer manner to print the three-dimensional part on the build platform; and
a gantry configured to move the build platform in a reciprocating pattern such that a top surface of the three-dimensional part being formed on the build platform travels within the build plane and out of the build plane, the movement being synchronized with the rotational rate of the belt wherein the gantry is confi

Assignees

• Stratasys Inc

Inventors

• Chillscyzn Steven A
• Comb James W
• Hanson William J
• Sanders J Randolph
• Bacus Michael W

Classifications

• Y10T156/17

  Surface bonding means and/or assemblymeans with work feeding or handling means · CPC title

• G03G15/169

  with means for preconditioning the toner image before the transfer (G03G15/095 and G03G15/11 take precedence) · CPC title

• B33Y10/00

  Processes of additive manufacturing · CPC title

• G03G15/2021

  Plurality of separate fixing and/or cooling areas or units, two step fixing · CPC title

• G03G2215/1695

  at the second or higher order transfer point · CPC title