Additive manufacturing

Abstract

The invention relates to additive manufacturing. Some examples include a melting apparatus for an additive manufacturing machine. The melting apparatus includes a housing movable in an x-direction across a build area for containing build material and flux. A heat source is housed in the housing for directing thermal energy to the build area and includes a warming source for emitting a first emission spectrum and a melting source for emitting a second emission spectrum. The control device is used to continuously modulate the thermal energy level generated by the heat source during the build cycle.

Description

[0001] This application is a divisional application of patent application number 201780089318.3, filed April 21, 2017, entitled "Additive Manufacturing". BACKGROUND

[0002] Additive manufacturing machines produce 3D objects by building up layers of construction material. Some additive manufacturing machines are commonly referred to as "3D printers." 3D printers and other additive manufacturing machines make it possible to convert a CAD (computer aided design) model or other digital representation of an object into a physical object. The model data can be processed into slices, each slice defining a portion of one or more layers of construction material that will form the object. BRIEF DESCRIPTION OF DRAWINGS

[0003] Figure 1 is a schematic side view of an example melting apparatus for an additive manufacturing machine according to aspects of the present disclosure.

[0004] Figure 2 is a flowchart of an example method of operating a melting apparatus of an additive manufacturing machine according to aspects of the present disclosure.

[0005] Figure 3 is a flowchart of another example method of operating a melting apparatus of an additive manufacturing machine according to aspects of the present disclosure.

[0006] Figure 4 is a schematic side view of an additive manufacturing machine according to aspects of the present disclosure.

[0007] Figures 5A-8B is a schematic side view and a schematic top view showing the sequence of an example four-pass melting cycle using a melting system of an additive manufacturing machine according to aspects of the present disclosure. DETAILED DESCRIPTION

[0008] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration specific examples in which the disclosure can be practiced. It is to be understood that other examples can be utilized and structural or logical changes can be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. It should be understood that features of the various examples described herein can be combined, in part or whole, with each other, unless specifically noted otherwise.

[0009] In some additive manufacturing processes, thermal energy is used to melt particles in a powdered build material together to form a solid object. The thermal energy to melt the build material can be generated, for example, by applying a liquid fusing agent to a thin layer of powdered build material in a pattern based on a slice of the object, and then exposing the patterned area to melting energy. A melting energy-absorbing component in the fusing agent absorbs the melting energy to help sinter, fuse, or otherwise melt the build material. The process is repeated layer by layer and slice by slice to complete the object.

[0010] Figure 1 is a schematic side view of a fusing apparatus 10 for an additive manufacturing machine according to aspects of the present disclosure. The fusing apparatus includes a housing 12, a thermal source 14, and a control device 16. The housing 12 is movable in an x-axis direction across a build area 18. The build area 18 can contain build material 20 and fusing agent 22. The thermal source 14 is contained in the housing 12. The thermal source 14 directs thermal energy toward the build area 18. The thermal source 14 includes a warming source or first thermal source 24 for emitting a first emission spectrum and a fusing source or second thermal source 26 for emitting a second emission spectrum.

[0011] The thermal source 14 remains energized during all cycles of a three-dimensional object build process. The warming source and the fusing source 24, 26 emit different color temperatures (i.e., emission spectra). The warming source 24 can be adjusted to maintain un-melted build material at a target control temperature. The melting energy from the fusing source 26 can vary and can be adjusted at each stage of the build process. The warming source 24 and the fusing source 26 can be independently and separately adjusted to emit independently modulated emission spectra.

[0012] Figure 2 is a flowchart of an example method 30 of operating a fusing apparatus of an additive manufacturing machine according to aspects of the present disclosure. At 32, thermal energy is generated by a thermal source. The thermal energy includes separate emission spectra including a first emission spectrum and a second emission spectrum. Each of the first emission spectrum and the second emission spectrum is oriented to emit longitudinally along a y-axis. At 34, the thermal source is translated along an x-axis over a build area. At 36, the thermal energy is continuously delivered on the build area during a build process of a three-dimensional object.

[0013] Figure 3is a flowchart of another example method 40 of operating a fusing apparatus of an additive manufacturing machine in accordance with aspects of the present disclosure. At 42, within a build chamber, radiant thermal energy is produced by a thermal energy source. The radiant thermal energy is separated into a first emission spectrum and a second emission spectrum. At 44, the thermal energy source is translated bi-directionally in a plane above a build area within the build chamber. At 46, the translating thermal energy source delivers first stage energy having the first emission spectrum to raise a thermal level of build material and fusing agent accommodated on the build area above a melting temperature. At 48, second stage energy having the second emission spectrum is delivered to maintain the melting temperature. At 50, the build material and fusing agent accommodated on the build area are convectively cooled. At 52, during construction of a three-dimensional object, within the build chamber, the maintained radiant thermal energy production maintains a warming temperature below the melting temperature.

[0014] Figure 4 One example of an additive manufacturing machine 100 including a fusing system 10 is shown. In addition to the fusing system or assembly 10, the additive manufacturing machine 100 includes a dispensing assembly 60 that is movable above a build chamber 58. The fusing system 10 and the dispensing assembly 60 are movable along an x-axis above the build chamber 58. The dispensing assembly 60 includes a print head 62 (or other suitable liquid dispensing assembly) mounted to a dispensing carriage 64 to selectively dispense fusing agent 22 and other liquid agents (if used). The build chamber 58 can accommodate build material 20 and fusing agent 22 as layers are formed. The build chamber 58 can be any suitable structure to support or accommodate build material 20 for fusing within a build area 18, including a bottom layer of build material 20 and in-process slices as well as other object structures. For example, for a first layer of build material 20, the build chamber 58 can include a platform surface that is vertically movable along a y-axis to accommodate the layering process. For subsequent layers of build material 20, the build area 18 can be formed on a bottom build structure within the build chamber 58 that includes un-fused build material and fused build material forming object slices. A controller 16 can control the energy levels, as discussed further below. The controller 16 can also control other functions and operations of the additive manufacturing machine 100.

[0015] During the entire build process or build cycle of the three-dimensional object, thermal energy is continuously emitted from the heat sources 14 to comply with Flicker regulations that adjust for power usage surges. The energy levels of the lamps of the heat sources 14 can be individually modulated, adjusted, and tuned during the build process to achieve target powder temperatures and part temperatures. Alternatively, the energy levels of the lamps can be modulated, adjusted, and tuned together in (group) sets or by source type during the build process to achieve target powder temperatures and part temperatures. For example, the warming source 24 and the fusing source 26 can be independently and separately adjusted to emit independently modulated emission spectra. In one example, the power of the warming source 24 can be adjusted by a control loop using thermal feedback from the infrared camera 70 and the controller 16, such as a proportional-integral-derivative (PID) controller. For example, the energy level of the warming source 24 can be modulated using the PID controller 16 based on temperature feedback from the non-contact IR sensor to maintain the build material temperature at a target setpoint. In one example, the energy level of the fusing source 26 is modulated based on a predetermined power modulation. In another example, the energy level of the fusing source 26 is modulated based on thermal feedback of the molten build material temperature using a non-contact IR camera and a PID controller. In one example, the pulse width modulation (PWM) varies between 69% and 78% within a four-stage fusing cycle.

[0016] Figures 5A-8B are schematic side and top views showing an example sequence of a four-stage fusing cycle using a fusing system of an additive manufacturing machine. Each stage includes a plurality of operations that can occur simultaneously during the respective stage. The fusing system 10 and the distribution assembly 60 move bidirectionally along the same motion path above the build area 18 within the build chamber 58 so that the carriages 12, 64 can follow each other across the build area 18. The dual-carriage fusing system in which the carriages 12, 64 move along the same motion path facilitates faster slew speeds and overlapping functions in each stage. According to one example, the direction of movement of the stages is indicated by the arrows in Figures 5A-8B The carriages 12, 64 of the fusing system 10 and the distribution assembly 60 move entirely and integrally across the build area 18 and can be positioned on either side of the build area 18. Typically, rollers 72 can be included on the fuser carriage 12 to spread the build material 20 to form a layer on the build area 18. The distributor carriage 64 carries the agent distributor 62 to distribute the fusing agent 22 onto each layer of the build material 20. The heat sources 14 carried by the carriage 12 heat and irradiate the layered build material 20 and the fusing agent 22.

[0017] With respect to the heat sources 14 of the fusing system 10, the heat sources 14 can include any suitable number and type of heat sources to heat and irradiate the build material. Heat sources 14 including lower color temperature warming lamps and higher color temperature fusing lamps can provide control of heating and fusing of the build material. Figures 5A-8B The illustrated heat sources 14 include warming and fusing sources 24, 26. The fusing sources 26 can have a higher color temperature to sufficiently heat the fusing agent 22 and build material 20 to selectively fuse the build material 20. The warming sources 24 can have a lower color temperature to selectively heat the build material 20 without causing the build material to fuse. In one example, the fusing sources 26 have a 2750 Kelvin color temperature. The fusing sources 26 can include a series of heat lamps each arranged longitudinally parallel to a main axis disposed along the y-axis. In one example, the warming sources 24 have a 1800 Kelvin color temperature. Other color temperatures can also be suitable. Single or multiple warming and fusing sources 24, 26 can be included. The fusing lamps 24 are used to irradiate the build material 20 with fusing energy.

[0018] Referring to Figure 5A and Figure 5B , in a first phase of the example sequence, the fuser carriage 12 moves across the build area 18 starting from the left side of the build area 18 toward the right side of the build area 18. The warming lamps 24 are energized to heat the underlying slice of build material 20 in front of the roller 72 as the roller 16 forms a first layer or next layer of build material 20 across the build area 18. The roller 72 is positioned to contact the build material 20 during the first spreading phase. Thermal energy from the warming sources 24 reflects from the previous layer of build material 20 to uniformly heat the build area. After the first phase is complete, the fuser carriage 12 is positioned at the right side of the build area 18 and is prepared for a second spreading phase.

[0019] The second phase is illustrated in Figure 6A and Figure 6B . In the second phase, as the fuser carriage 12 moves back across the build area 18 from the right side to the left side, the warming sources 24 are turned on to heat the new layer of build material 20 in front of the distributor carriage 64 that follows the fuser carriage 12 across the build area 18 to distribute fusing agent and / or detailing agent onto the heated build material 20 based on the pattern of the next object slice. The roller 72 can complete the spreading of build material 20 in front of the warming lamps 24 and the distributor carriage 64 that can not have been fully spread during the first phase.

[0020] The third phase is illustrated in Figure 7A and Figure 7BThe third phase is a fusing phase. In the third phase, the distributor carriage 64 moves from left to right above the build area 18 to distribute the fusing agent and / or detailing agent 22 onto the build material 20, with the fuser carriage 12 following, where the fusing source 26 is turned on to expose the patterned build material to fusing energy.

[0021] In the fourth phase, as shown in FIG. 4C, the fuser carriage 12 moves from right to left above the build area 18, and the fusing source 26 is turned off to expose the patterned build material to no fusing energy. Figure 8A and Figure 8B In the fourth phase, as shown in FIG. 4C, the fuser carriage 12 moves from right to left above the build area 18, and the fusing source 26 is turned off to expose the patterned build material to no fusing energy. The four-phase process can be repeated for successive layers of build material as the object is manufactured layer-by-layer and slice-by-slice. When all layers of build material for the three-dimensional object have been completed, the build cycle is complete.

[0022] While specific examples have been shown and described herein, various alternatives and / or equivalents can be used in place of the specific examples shown and described herein without departing from the scope of the disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and their equivalents.

Claims

1. A melting device for an additive manufacturing machine, comprising: a housing movable in an x-direction across a build area for containing build material and flux; a roller attached to the housing and configured to spread the build material, the roller being raiseable and lowerable in a y-direction perpendicular to the x-direction and positioned to contact the build material during the spreading; a heat source housed in the housing, the heat source configured to direct radiant thermal energy toward the build region, the radiant thermal energy being separated into a first emission spectrum for delivering first-stage energy to raise the thermal level of the build material and the flux above a melting temperature, and a second emission spectrum for delivering second-stage energy to maintain the melting temperature; and A control device configured to: Repeatedly bidirectionally translating the heat source in a plane above the build area to alternately deliver first stage energy-second stage energy and then second stage energy-first stage energy; and After the spreading of the building material, the roller is lifted in the y-direction to avoid thermal contact between the roller and the building material.

2. The melting apparatus of claim 1 , wherein the heat source is configured to continuously modulate the radiant heat energy during a build cycle.

3. The melting apparatus of claim 2, wherein during the build cycle, the first emission spectrum is adjustable independently of the second emission spectrum.

4. The melting apparatus of claim 1 , wherein the heat source comprises a warming source having controlled pulse width modulation within the build cycle.

5. The melting apparatus of claim 1 , wherein the control device comprises an infrared camera and a proportional-integral-derivative controller.

6. The melting apparatus of claim 1, wherein the heat source comprises a melting source comprising at least two lamps. 7 . The melting apparatus of claim 1 , wherein the first emission spectrum has a lower emission energy level than the second emission spectrum.

8. A method of operating a melting system of an additive manufacturing machine to form a three-dimensional object, comprising: spreading a build material over a build area via a roller, wherein the roller is positioned in contact with the build material during the spreading; generating thermal energy from a heat source, the thermal energy having a separate emission spectrum including a first emission spectrum and a second emission spectrum, each of the first emission spectrum and the second emission spectrum being oriented to emit longitudinally along a y-axis; translating the heat source over the build area along an x-axis to deliver a first phase of energy having the first emission spectrum and a second phase of energy having the second emission spectrum; as well as During the building process of the three-dimensional object, the thermal energy is continuously delivered to the building area so as to alternate between first stage energy-second stage energy and then second stage energy-first stage energy, wherein the first emission spectrum is used to raise the thermal level of the build material and flux contained on the build area to above a melting temperature, and the second emission spectrum is used to maintain the melting temperature, wherein, after the spreading, the roller is lifted away from the build material to avoid thermal contact between the roller and the build material.

9. The method according to claim 8, comprising: heating a build material contained on the build area to a first temperature according to the first emission spectrum; and The build material and flux contained on the build area are heated to a second temperature by the second emission spectrum, wherein the second temperature is greater than the first temperature.

10. The method according to claim 8, comprising: During the building process, the energy level of the continuously delivered thermal energy is modulated.

11. The method according to claim 8, comprising: The heat source is controlled to deliver a modulated level of the thermal energy.

12. A method of operating a melting system of an additive manufacturing machine to form a three-dimensional object, comprising: The build material is spread over a build area in the build chamber by rollers, wherein said roller being positioned in contact with said building material during said spreading; In the construction chamber, radiant heat energy is generated by a thermal energy source, and the radiant heat energy is separated into a first emission spectrum and a second emission spectrum; bidirectionally translating the thermal energy source in a plane above a build area within the build chamber to: delivering a first phase of energy having the first emission spectrum to raise a thermal level of a build material and flux contained on the build area to above a melting temperature; delivering a second phase of energy having the second emission spectrum to maintain the melting temperature; repeatedly translating the thermal energy source in the plane to alternately deliver first stage energy-second stage energy and then second stage energy-first stage energy, wherein after the spreading, the roller is lifted off the build material to avoid thermal contact between the roller and the build material; convectively cooling the build material and the flux contained on the build area; and During the building process of the three-dimensional object, within the build chamber, radiant heat energy generation is maintained to maintain a warming temperature below the melting temperature.

13. The method according to claim 12, comprising: During the building process, the energy level of the continuously delivered thermal energy is modulated. The method of claim 12 , wherein during the construction process, the first emission spectrum is adjustable independently of the second emission spectrum.

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