WO2021006897A1

WO2021006897A1 - Fusing lamps with varied output power

Info

Publication number: WO2021006897A1
Application number: PCT/US2019/041242
Authority: WO
Inventors: Eric Collins; Morgan Scott DIVINE; Robert D. Davis; Pierre J. Kaiser; Michael Ewe; Arthur H. Barnes
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2019-07-10
Filing date: 2019-07-10
Publication date: 2021-01-14

Abstract

A system, method, and apparatus for varying output power for two or more fusing lamps in a 3D printer is disclosed. For example, the system includes a first fusing lamp to operate at a first voltage and a second fusing lamp to operate at a second voltage. The system may include a controller communicatively connected to the first fusing lamp and the second fusing lamp, wherein the controller sets the first voltage and the second voltage in response to a multi-lamp power output setting, a lamp power minimum, and a lamp power maximum.

Description

FUSING LAMPS WITH VARIED OUTPUT POWER

BACKGROUND

[0001] In additive manufacturing, such as three dimensional (3D) printing, the build material utilized may be spread by a movable carriage. The movable carriage may also include fusing lamps to emit energy towards the build material.

[0002] When a fusing agent is deposited into the build material, the fusing agent may absorb energy emitted by the fusing lamps. The absorbed energy may be converted to heat sufficient to fuse the build material together in that region. After the fusing lamps emit energy towards the build material, another layer of fresh build material may be deposited on or spread across a build platform for further application of fusing agent and fusing by the fusing lamps. Layer by layer build material may be added and fused until a 3D object is formed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Certain examples are described in the following detailed description and in reference to the drawings, in which:

[0004] Fig. 1 is a block diagram of an example system for varying output power for two fusing lamps in a 3D printer.

[0005] Fig. 2 is a schematic diagram for an example system for varying output power to two fusing lamps in a 3D printer, the lamps being active.

[0006] Fig 3 is a block diagram for an example movable carriage of a 3D printer, the movable carriage including three fusing lamps.

[0007] Fig. 4 is a schematic diagram for an example movable carriage of a 3D printer, the movable carriage including three fusing lamps in an activated state.

[0008] Fig. 5 is a schematic diagram for an example movable carriage of a 3D printer, the movable carriage including three fusing lamps in an activated state each lamp with their own power output.

[0009] Fig. 6 is a block diagram for an example of two fusing lamps with voltages controlled by a multi-lamp voltage calculator.

[0010] Fig. 7 is a flow diagram of an example method 700 for varying output power for two fusing lamps in a 3D printer. [0011] The same numbers are used throughout the disclosure and the figures to reference like components and features. Numbers in the 100 series refer to features originally found in Fig. 1 , numbers in the 200 series refer to features originally found in Fig. 2, and so on.

DETAILED DESCRIPTION

[0012] The present disclosure relates to additive manufacturing such as 3D printing. In general, the techniques described here refer to the way power output can be varied in fusing lamps used to induce fusing of build material particles together. In these devices build material may need to be spread over a build area of a build platform. Fusing agent may be added and then fusing lamps may turn on to deliver power, for example by radiation, to the build material and fusing agent. As used herein, build material may include powder as well as short fiber build materials that may, for example, have been cut into short lengths from long strands or threads of material. Build materials may also be plastic, ceramic, metal powders, or other powder-like materials alone or in combination with one another. Use of the term powder may refer to a specific type of build material, however other types of build material may be used in place of powder and describing powder in this specification is used as one example of the present technique. Further, at time the build material may be spread and later have printing liquid applied to it. Even when other components such as printing liquid or fusing agent added, it may still be generally referred to as build material and still be within the scope of the present techniques. The build material, fusing agent, and 3D printing systems generally disclosed herein may also refer to chemical binder systems and metal type 3D printing systems. Accordingly, references to fusing agent also may refer to chemical binding or metal type 3D printing including the methods and build material corresponding to those respective systems taking into account the techniques disclosed herein.

[0013] In some 3D printing systems with a shared spreading and fusing carriage, build material, such as powder from the spreading process can accumulate on the fusing lamp glass. The fusing lamps can melt this powder, causing additional powder to collect on the fusing lamp glass of the carriage. The accumulated powder can disrupt the fusing process, damage the 3D printed parts, or necessitate lamp glass replacement. When contamination becomes excessive, the build can fail, and cleaning the lamp glass is difficult, sometimes resulting in broken fusing lamp glass.

[0014] The present disclosure also relates to the concept of unequal power distribution between fusing lamps and the method to determine the appropriate power of the two fusing lamps or lamp regions for the purposes of minimizing lamp glass contamination while controlling the fused part temperature to a set point. The present techniques enables granular control over the power distribution by fusing lamp to develop different fusing processes for a range of materials and part properties.

[0015] The techniques disclosed in this specification provide a variable power output based on the power set by the controller. This variable power can be governed by a percentage of power, an explicit definition for power output, or other power settings. In an example, each fusing lamp power output is governed by a proportional-integral-derivative (PID) feedback controller and using a temperature set point to determine an output voltage. The PID controller may provide a single term output used to calculate the voltages for each of the fusing lamps to provide a portion of the target power output. In an example, a load balancing calculation may determine separate output voltages for the center and outer fusing lamps. This kind of load balancing process can include a proportional term, a minimum lamp power value, and maximum lamp power value. A load balancing calculation applies the proportional term to the PID controller output voltage to determine voltages for each lamp and further rebalances the distribution of voltages to enforce the minimum and maximum power output value for each lamp.

[0016] Fig. 1 is a block diagram of an example system for varying output power for two fusing lamps in a 3D printer 100. The 3D printer 100 may operate by fusing enacted by a first fusing lamp 102 and a second fusing lamp 104. The second fusing lamp 104 may be located proximate to an edge 106 of a movable carriage 108. The first fusing lamp 102 is located further from the edge 106 compared to the second fusing lamp 104. In an example, the first fusing lamp 102 may be located in the center of the movable carriage 108 and the second fusing lamp 104 may be located towards the edge 106 of the movable carriage 108.

[0017] The first fusing lamp 102 and the second fusing lamp 104 may be controlled by a controller 1 10. In an example, the controller individually calculates the voltage for each of the first fusing lamp 102 and the second fusing lamp 104. Although two fusing lamps are shown, any number of lamps more than two is contemplated as part of this system. Further, while two distinct lamps are shown, the techniques shown here may also apply to a single fusing lamp with at least two regions that can be independently adjusted for a specified power output.

[0018] The movable carriage 108 is located above a build platform 1 12 upon which build material 1 14 may be deposited in a build area. In an example, the build material is a powder although other spreadable build materials are possible. In an example, the movable carriage 108 has a dual purpose as a build material spreader and can spread the build material 1 14 along the surface of the build platform 1 12.

[0019] The 3D printer 100 may also eject fusing agent 1 16 using a print pen into the build material at locations designated for fusing. In an example, the fusing agent 1 16 is a liquid although other agents to enable fusing are also contemplated. The fusing agent 1 16 may heat up when exposed to sufficient energy thereby causing the build material surrounded by the fusing agent to fuse together. Rather than providing a single output voltage for both the first fusing lamp 102 and the second fusing lamp 104, the controller 1 10 independently sets the voltage for each of the fusing lamps.

[0020] Fig. 2 is a schematic diagram for an example system for varying output power to two fusing lamps in a 3D printer, the lamps being active. Like numbered items are as discussed above with respect to Fig. 1 . When the lamps are active, the movable carriage 108 may be moving across the portion of the build platform 1 12 where the build material 1 14 and fusing agent is deposited. The first fusing lamp 102 is operating at a first voltage to emit a first power output 200. The second fusing lamp 102 is operating at a second voltage to emit a second power output 202.

[0021] In an example, the first voltage and second voltage differ and are set by the controller 1 10. In an example, the second voltage is set to be lower than the first voltage so that the second power output 202 is lower than the first power output 200. In an example, the fusing lamp closest to the edge 106 of the movable carriage 108 is set by the controller to emit a lower power output relative to the power output of a fusing lamp further from the edge of the movable carriage. In an example, more than two fusing lamps may be included in a system and activated. In an example with more than two fusing lamps, the center most fusing lamp, or fusing lamp furthest from an edge of the movable carriage 108 is set to have the highest power output.

[0022] The movable carriage 108 may be used to spread build material 1 14 across the build platform 1 12. Each trip across the build area of the build platform where the build material is accumulating may be referred to as a pass. During each pass across the build area, the movable carriage may operate the fusing lamps, spread build material, or both. In an example, the build material may have different intrinsic qualities in the way that it fuses based on the specific material being used.

In an example, one build material may fuse together more strongly if it is first exposed to a lower power fusing lamp followed by a higher power fusing lamp. In another example, another build material used may fuse a different color if a temporally short and intense amount of heat is used from a single fusing lamp. In an example, loose build material may inadvertently fuse to the edge 106 of the movable carriage 108 if the second power output 202 is too high. To address each of these and other granular lamp control manufactures, the controller 1 10 may individually set the voltages for each of the fusing lamps for each pass of the movable carriage across the build area of the build platform 1 12.

[0023] In an example, the movable carriage 108 is used to spread the build material 1 14 or has the potential to accumulate build material 1 14 on its edge 106 through static cling or other means. To account for this possibility, the controller 1 10 may set the voltage for the second fusing lamp 104 to be low relative to the voltage of the first fusing lamp 102. In an example, the second voltage for the second fusing lamp 104 would be low enough that build material 1 14 in contact with the edge 106 of the movable carriage 108 would be less likely to fuse and stick to the fusing glass on the movable carriage 108. Using a lower voltage for a lower power output by the second fusing lamp reduces the risk of damage or occlusion of portions of the fusing plate glass on the movable carriage 108.

[0024] In an example, the total power output of all of the fusing lamps in the movable carriage is held constant to match a target power output setting set by the controller 1 10. This target power output setting may correspond to a manually set value determined by a user, a set value adjusted by a preprogramed routine, a calculated value based on a measurement of temperature in the build area, a target temperature provided to the controller, or another similar value. Accordingly, while the total power felt by the fusing agent remains relatively constant, the exact proportions of power provided by each fusing lamp may change relative to one another. For example, if the power provided by the second fusing lamp 104 is decreased, the power provided by the first fusing lamp may be increased to ensure the target power output setting is delivered to the build area by the total collection of fusing lamps delivering power in that direction.

[0025] In an example, each fusing lamp has a lamp power minimum. The lamp power minimum may be set by the controller or set by the design of the fusing lamp where its particular power minimum is communicated to the controller to be accounted for in the controller calculations. A fusing lamp may have a power minimum in order to reduce potential lag times in lamp functionality. For example, as the movable carriage 108 makes passes according to a certain schedule it may need to activate the fusing lamps to a certain level by the time a pass is being made. It takes a substantially longer time to power up a completely powered off fusing lamp rather than raise the power level of a fusing lamp that is already on at a particular lamp power minimum. Enforcing a lamp power minimum enables the 3D printer to have the fusing lamps at a desired power output more quickly, thereby increasing the quality of the build with each pass. Keeping a lamp close to a desired power level reduces cases where a lamp is unable to reach a desired power level in time for a pass of the carriage across a build area.

[0026] In an example, the controller 1 10 represents a combination of component including a fusing lamp servo, load balancer, and a separate fusing lamp controller for each fusing lamp. In this example, each fusing lamp has a corresponding sine wave converter to take a pulse width modulated signal and convert it into a voltage to be supplied to the fusing lamp. In an example, a target temperature may be provided to the load balancer which calculates a split needed so that the target temperature may be achieved while also splitting the power to be delivered by each of the lamps involved. In an example the load balancer may also account for lamp minimums and lamp maximums such that if one of the lamps would be set above a maximum or below a minimum the setting is stopped at the respective max or min and the remaining difference is made up for by the load balancer shifting power to be delivered to another fusing lamp. Accordingly, while the term controller is used herein, many of the same operations may be done by load balancer, in cases where load balancing is used.

[0027] Fig. 3 is a block diagram for an example movable carriage of a 3D printer, the movable carriage including three fusing lamps. Like numbered items are described above with respect to Fig. 1 .

[0028] The movable carriage 108 is shown with three fusing lamps including the first fusing lamp 102 the second fusing lamp 104 and the third fusing lamp 300. In this example, the third fusing lamp is closer to a second edge of the movable carriage 108 when compared to the first fusing lamp 102. In an example, the first fusing lamp 102 may be located between the second fusing lamp 104 and the third fusing lamp 300. In an example, the first fusing lamp 102 may be located centrally within a movable carriage 108 while the second fusing lamp 104 and the third fusing lamp 300 are located towards the inner periphery of the movable carriage 108. Each of the fusing lamps may be independently controlled by the controller 1 10.

[0029] Fig. 4 is a schematic diagram for an example movable carriage of a 3D printer, the movable carriage including three fusing lamps in an activated state. Like numbered items are as described with respect to Fig. 1 , Fig. 2, and Fig. 3.

[0030] The first fusing lamp 102 is shown operating at a first voltage set by the controller 1 10 to emit a first power output 200. The second fusing lamp 104 and the third fusing lamp 300 are shown operating at a second voltage set by the controller 1 10 to each emit a second power output 202. In an example, the second power output 202 is less than the first power output 200. In an example, the second power output is reduced in order to reduce the amount of build material 1 14 inadvertently fused to the first edge 106 or the second edge 302 of the movable carriage 108. In an example, the second edge 302 may also be used in spreading build material as the movable carriage 108 moves across a build platform.

[0031] Fig. 5 is a schematic diagram for an example movable carriage of a 3D printer, the movable carriage including three fusing lamps in an activated state each lamp with their own power output. Like numbered items are as described above with respect to Fig. 1 , Fig. 2, and Fig. 3.

[0032] The third fusing lamp 300 may be set to operate with a third voltage by the controller 1 10. The third fusing lamp 300 operating with a third voltage outputs a third power output 500 that differs from the second power output 202 and the first power output 200. In an example, the third power output 500 may be less than the first power output 200. In an example, the third power output 500 may be more than the second power output 200. Any combinations of power outputs by the fusing lamps may be contemplated and enacted by the controller 1 10 in order to meet the specifications of a particular build. In an example, a build for a 3D printer may use a material or fusing agent that is applied in a non-uniform or customized way.

Accordingly, the use of multiple fusing lamps and a controller 1 10 may allow adjustable power output for each of the fusing lamps that can change with each pass of the movable carriage. Furthermore, more than three fusing lamps are

contemplated in these techniques where the fusing lamps be set to different power output levels by the controller.

[0033] Fig. 6 is a block diagram for an example of two fusing lamps with voltages controlled by a multi-lamp voltage calculator. Like numbered items are as described above with respect to Fig. 1 .

[0034] The controller 1 10 may include a multi-lamp voltage calculator 600. In certain instances, a controller 100 may receive an instruction to provide a specified total power output to the build material. Using this specified total power output, the multi-lamp voltage calculator 600 may calculate what power output should be provide by each of the fusing lamps the controller 1 10 is connected to. Further, the multi-lamp voltage calculator 600 may need to account for any lamp power maximums and lamp power minimums.

[0035] In an example, each fusing lamp has a lamp power maximum. The lamp power maximum may be set by the controller. Lamp power maximums may be set in order to reduce possible lamp degradation or fire risk due to overheating. To account for both the lamp power minimum and the lamp power maximums, a multi lamp voltage calculator 600 may adjust the power output of one or more lamps to comply with these minimums and maximums while still ensuring the specified total power output by the fusing lamps meets a specified total power output figure designated for particular pass. In an example, this power output can change each pass and accordingly, the power output for each lamp may change with each pass of the movable carriage over the build area. Once a power output for a particular lamps is determined by the multi-lamp voltage calculator 600, the controller 1 10 may then identify the voltage needed for each lamp to reach its designated power output and set the voltage for each lamp for a particular pass.

[0036] Fig. 7 is a flow diagram of an example method 700 for varying output power for two fusing lamps in a 3D printer. At block 702, the method 700 includes setting a first voltage and a second voltage with a controller in response to a multi lamp power output setting, a lamp power minimum, and a lamp power maximum. At block 704, the method 700 includes operating a first fusing lamp at the first voltage. At block 706, the method 700 includes operating a second fusing lamp at the second voltage.

In an example, the method 700 includes calculating, with the controller, a multi-lamp power output setting based on a target output power value provided to the controller, wherein the first fusing lamp operating at a first voltage and the second fusing lamp operating at the second voltage provide the target output power value based on the multi-lamp power output setting calculated by the controller. The method 700 may occur with the first fusing lamp and the second fusing lamp located on a movable carriage. In this example, the movable carriage may pass over a build platform. In an example, the method 700 may occur with the second fusing lamp located proximate to an edge of the movable carriage. In this example, the first fusing lamp is located further from the edge of the movable carriage compared to the distance between the edge of the movable carriage and the second fusing lamp. In this example, the multi-lamp power output setting also sets the first voltage to be greater than the second voltage.

In an example, the first voltage and the second voltage are re-set each time the first fusing lamp and the second fusing lamp pass over a build area. In another example, the method 700 may occur with the first fusing lamp and the second fusing lamp located on a movable carriage including a first edge and a second edge. In this example, the second fusing lamp is located proximate to a first edge of the movable carriage. Also in this example, the method 700 includes operating a third fusing lamp at the first voltage, where the third fusing lamp is located proximate to a second edge of the movable carriage. In this example, the first fusing lamp is located between the second fusing lamp and the third fusing lamp and the first voltage is greater than the second voltage. The method 700 may also include setting, with the controller, the multi-lamp power output setting based on a manually set value without performing a mathematical operation using the manually set value prior to setting the multi-lamp power output setting. The method 700 may also include calculating with the controller, the multi-lamp power output setting from a target temperature provided to the controller. In an example, the controller may calculate the multi-lamp power output setting from a target temperature that is provided to the controller for each pass of a plurality of passes the first fusing lamp and the second fusing lamp make over a build platform.

Claims

CLAIMS What is claimed is:

1 . A system for varying output power for two or more fusing lamps in a 3D printer, comprising:

a first fusing lamp to operate at a first voltage;

a second fusing lamp to operate at a second voltage;

a controller communicatively connected to the first fusing lamp and the

second fusing lamp, wherein the controller sets the first voltage and the second voltage in response to a multi-lamp power output setting, a lamp power minimum, and a lamp power maximum.

2. The system of claim 1 , wherein the controller is to calculate the multi-lamp power output setting based on a target output power value provided to the controller, wherein the first fusing lamp operating at a first voltage and the second fusing lamp operating at the second voltage combine to provide the target output power value based on the multi-lamp power output setting calculated by the controller.

3. The system of claim 1 , wherein the first fusing lamp and the second fusing lamp are located on a movable carriage.

4. The system of claim 3, wherein the movable carriage is passed over a build platform.

5. The system of claim 4, wherein:

the second fusing lamp is located proximate to an edge of the movable

carriage;

the first fusing lamp is located further from the edge of the movable carriage compared to the distance between the edge of the movable carriage and the second fusing lamp; and wherein the multi-lamp power output setting sets the first voltage to be greater than the second voltage.

6. The system of claim 1 , wherein the first voltage and the second voltage are re-set each time the first fusing lamp and the second fusing lamp pass over a build area on the build platform.

7. The system of claim 1 , comprising:

a movable carriage, wherein the first fusing lamp and the second fusing lamp are located on the movable carriage comprising a first edge and a second edge, wherein the second fusing lamp is located proximate to a first edge of the movable carriage;

a third fusing lamp to operate at the first voltage, the third fusing lamp located proximate to a second edge of the movable carriage, wherein the first fusing lamp is located between the second fusing lamp and the third fusing lamp, wherein the first voltage is greater than the second voltage.

8. The system of claim 1 , wherein the controller sets voltage based on a manually set value.

9. The system of claim 1 , wherein the controller calculates the multi-lamp power output setting from a target temperature provided to the controller.

10. The system of claim 1 , wherein the controller calculates the multi-lamp power output setting from a target temperature that is provided to the controller for each pass of a plurality of passes the first fusing lamp and the second fusing lamp make over a build area of a build platform.

1 1. A method for varying output power for two or more fusing lamps in a 3D printer, comprising:

setting a first voltage and a second voltage with a controller in response to a multi-lamp power output setting, a lamp power minimum, and a lamp power maximum; operating a first fusing lamp at the first voltage; and

operating a second fusing lamp at the second voltage.

12. The method of claim 1 1 , comprising calculating, with the controller, the multi-lamp power output setting based on a target output power value provided to the controller, wherein operating the first fusing lamp at a first voltage and operating the second fusing lamp at the second voltage provide the target output power value based on the multi-lamp power output setting calculated by the controller.

13. The method of claim 1 1 , wherein the first fusing lamp and the second fusing lamp are located on a movable carriage.

14. An apparatus for varying output power for two or more fusing lamps in a 3D printer, comprising:

a movable carriage to move over a build platform;

a first fusing lamp to operate at a first voltage, the first fusing lamp located on the movable carriage;

a second fusing lamp to operate at a second voltage, the second fusing lamp located on the movable carriage proximate to an edge of the movable carriage, wherein the first fusing lamp is located further from the edge of the movable carriage compared to the distance between the edge of the movable carriage and the second fusing lamp; and

a controller communicatively connected to the first fusing lamp and the

second fusing lamp, wherein the controller sets the first voltage and the second voltage in response to a load balance setting, a lamp power minimum, and a lamp power maximum, wherein the multi-lamp power output setting sets the first voltage to be greater than the second voltage.

15. The apparatus of claim 14, wherein a third fusing lamp operates at a third voltages.