A three-dimensional (3D) printing system can be used to form 3D objects. A 3D printing system performs a 3D printing process, which is also referred to as an additive manufacturing (AM) process, in which successive layers of material(s) of a 3D object are formed under control of a computer based on the 3D model or other electronic representation of the object. The layers of the object are successively formed until the entire 3D object is formed.
Some implementations of the present disclosure are described with respect to the following figures.
In a 3D printing system, a build material (or multiple different build materials) can be used to form a 3D object, by depositing the build material(s) as successive layers until the final 3D object is formed. A build material can include a powdered build material that is composed of particles in the form of fine powder or granules. The powdered build material can include metal particles, plastic particles, polymer particles, or particles of other materials. The powdered form of the build material makes the build material free flowing in some examples.
Build material(s) can be transported from a build material reservoir (or multiple build material reservoirs) of the printing system to a printing bed (or more simply “bed”) of the printing system, where layers of the build material(s) are formed on the bed. The printing bed can also be referred to as a build platform. A build material is delivered in metered amounts and at specified temperatures.
In some examples, a build material can be transported by a conveyor belt that is able to carry the build material from the reservoir to a target delivery location. A “conveyor belt,” or more simply a “belt,” can refer to a transport structure having a transport surface on which a build material can be provided for transport between different locations in a printing system; note that further structures can be formed on the transport surface, where such further structures can define cavities in which the build material can be received for transport. Such further structures are described further below.
The conveyor belt can be moved by a drive system that includes rollers. A roller can refer to a rotatable member that is able to engage an inner surface of the belt to cause movement of the belt as the roller rotates.
During operation of a printing system, particles of a powdered build material transported by a conveyor belt can seep through small cracks or openings (such as around the side edges of the conveyor belt) and enter a region containing the drive system. Such particles of the build material that enter the drive system can be referred to as stray build material. The stray build material can accumulate over time, and can interfere with proper operation of the drive system. For example, the stray build material can clog up parts of the drive system and may even cause damage to some parts.
To prevent stray build material from entering the drive system from the transport surface of the conveyor belt, a seal can be provided at the side edges of the conveyor belt. The seal can be provided by sealing structures arranged along the side edges of the conveyor belt. However, the sealing structures can wear out over time with use, and can thus be less effective. Also, maintaining and/or repairing such sealing structures can be expensive. Moreover, adding such sealing structures to a printing system can increase the complexity and cost of the printing system.
In accordance with some implementations of the present disclosure, as shown in
The inner surface 116 of the belt 102 includes transport structures 118 defining cavities 120 to carry stray build material that has seeped into an inner region 122 of the belt 102, where the drive system 108 is located in the inner region 122. Each cavity 120 is able to receive a respective volume of stray build material.
The transport structures 118 are inward protrusions that project from the inner surface 116 of the belt 102. In some examples, the inward protrusions can rise from the inner surface 116 of the belt 102 in a direction that is generally perpendicular to the inner surface 116, or in a direction that is inclined at an angle (different from a right angle) with respect to the inner surface 116.
The transport structures 118 effectively provide a teeth profile. Although not shown in
Stray build material refers to build material that has seeped from the outer surface 104 of the belt 102 into the inner region 122. Within the inner region 122, the stray build material can fall downwardly, due to gravity, towards the roller 114. The stray build material can pass through the roller 114 (which has an interstitial design to provide gaps through which the stray build material can pass) to the inner surface 116 of the belt 102. Further details regarding the interstitial design of the roller 114 (and possibly other rollers) of the drive system 108, are discussed further below.
Portions of the stray build material are carried within the cavities 120 between the transport structures 118, upwardly generally along the direction of movement of the belt 102, as indicated by arrow 124.
As shown in
The combination of the inner transport chute 202A and the interconnecting transport chute 204A provides a transport conduit along which the stray build material flows away from the inner surface 116 of the belt 102 to a build material reservoir that is outside the inner region 122 of the belt 102. Generally, a “transport chute” can refer to a structure that defines a path along which a material (e.g. a stray build material) can flow or otherwise be carried.
In other examples, just one transport chute or more than the two separate transport chutes 202A and 204B can be used to carry stray build material from the inner region 122 to outside of the inner region 122.
The ends of the roller 302 are rotatably mounted to side panels 306 and 308 of the printing system 300, where the side panels 306 and 308 are part of a housing of the printing system 300. The side panels 306 and 308 partially define the inner region 122 (
An outer housing 305 is also provided that is adjacent a portion of the outer surface 104 of the belt 102. The outer housing 305 is arranged to maintain a build material between the outer surface 104 of the belt 102 and the inner surface of the outer housing 305.
The interconnecting transport chutes 204A and 204B can be attached to the side panels 308 and 306, respectively.
In
The interconnecting transport chute 204A is provided on the right side of the print system 300 in the view of
The inner transport chute 202B extends to the first end portion of the interconnecting transport chute 204B, to allow for communication of stray build material through the transport path of the inner transport chute 202B to the transport path of the interconnecting transport chute 204B.
In examples according to
Each ring-shaped rolling structure 320 or 322 includes a gear profile (in the form of a toothed wheel), where protrusions of the gear profile of the ring-shaped rolling structure can engage the teeth profile of the inner surface 116 of the belt 102, such that the belt 102 can be moved by rotation of the rolling structure.
Although not entirely visible in
Although not depicted in
As further shown in
The inner transport chutes 202A and 202B can be attached to the inner housing 330 and/or to other structures in the printing system 300.
In some examples, the diverting transport chutes 510 and 512 can form a general upside-down V profile, such that the diverting transport chutes 510 and 512 provide transport paths for stray build material that diverts away (outwardly) from an apex 511 of the upside-down V profile.
The stray build material that is diverted by the diverting transport chutes 510 and 512 fall generally along paths 514 and 516, respectively, towards the roller 114. The stray build material falling along paths 514 and 516 pass through the gaps between the ring-shaped rolling structures 402, and is caught by the cavities 120 formed inside the belt 102. The stray build material diverted by the diverting transport chutes 510 and 512 are passed to the left and right outer target portions of the belt 102, rather than to the middle portion of the belt 102. As a result, when the diverted stray build material is carried by the belt 102 to the upper portion of the build material delivery system 100, the diverted stray build material will fall towards the inner transport chutes 202A and 202B rather than towards the gap 506.
Since gravity is used to move the powdered build material through the inner transport chutes 202A and 202B, the inner transport chutes 202A and 202B are arranged at an incline. The inner transport chute 202A has a longitudinal axis (along its length) that is inclined at an angle α with respect to a horizontal axis. Similarly, the inner transport chute 202B has a longitudinal axis (along its length) that is inclined at an angle −α with respect to the horizontal axis. The angle α is greater than the critical incline angle below which the stray powdered build material will not slide due to friction between the stray powdered build material and the sliding surface of the inner transport chute.
In alternative examples, the inner transport chutes 202A and 202B can be arranged such that the angle α can be set small enough such that the inner transport chutes 202A and 202B can form a general upside-down V profile (similar to that formed by the diverting transport chutes 510 and 512), such that the inner transport chutes 202A and 202B provide transport paths for stray build material that diverts away (outwardly) from an apex (not shown) of the upside-down V profile. This alternative arrangement can eliminate the gap 506, such that the diverting transport chutes 510 and 512 would not have to be provided since there would not be stray build material falling through the eliminated gap 506.
The inner transport chutes 202A and 202B extend a certain vertical distance, which is dependent upon the horizontal distance along which each inner transport chute extends, and the respective angles α and −α of the inner transport chutes. In addition, the interconnecting transport chutes 204A and 204B extend a certain vertical distance back into the build material reservoir 318 (
The printing system 300 further includes the moveable conveyor belt 102 that can be moved in a circulating manner, along circulating direction 608. A circulating belt refers to a belt that moves in a closed loop on a continual basis. In other examples, other types of moveable conveyor belts with other movement patterns can be used.
In examples according to
An outer housing (503 as shown in
In some examples, the build material on the outer surface of the belt 106 (and more specifically, in the cavities defined by the transport structures 606) is transported to the delivery location 106 where the build material is deposited generally as indicated by arrow 622 (due to gravity and the motion of the belt 102) onto an upper surface 625 of a moveable delivery platform 624. The delivery platform 624 is moveable between a lowered position (the position shown in
As shown in
After the metered amount of the build material 626 has been deposited onto the upper surface 625 of the delivery platform 624, the belt 102 can be stopped, and an actuator 628 can be activated to raise the delivery platform 624 to the raised position. At the raised position, the upper surface 625 of the delivery platform 624 on which the deposited build material 626 is provided is substantially at the same height as the upper surface 604 of the printing bed 602 (or substantially at the same height of the upper surface of a target object 631 that has been formed so far by the 3D printing operation on the printing bed 602). Being “substantially at the same height” can mean that the upper surface 625 of the delivery platform 624 and the upper surface 604 of the printing bed 602 (or the upper surface of the target object 631) are aligned so that the deposited build material 626 can be pushed onto the upper surface 604 of the printing bed 602 (or the upper surface of the target object 631) from the upper surface of the delivery platform 624.
The combination of the belt 102, rollers 110, 112, and 114, the delivery platform 624, and the actuator 628 (along with other components, such as the motor to drive the roller 110, 112, and/or 114) can be collectively considered to be a build material delivery system that is useable within the printing system 300. The build material delivery system is to transport a build material from a build material reservoir below the printing bed 602 to the delivery location 106. With this arrangement, the powdered build material can be stored below the printing bed 602, which enables a compact (lower height) architecture (compared to printing systems where the powdered material is stored above the printing bed and is gravity fed to the printing bed).
After the delivery platform 624 has been moved by the actuator 628 to the raised position, a spreader 636 (moveable along a spreading axis 630) can be used to spread the deposited build material 626 across the upper surface of the target object 631. The spreader 636 can be in the form of a blade or a roller, as examples.
As further shown in
In other examples, instead of or in addition to using the printhead 634 to deliver a chemical agent, the 3D printing system 300 can use laser sintering that uses a laser beam to sinter portions of powdered build material to bind such portions. In further examples, techniques or mechanisms according to some implementations can be applied to other types of 3D printing systems in which a powdered build material is to be delivered to a printing bed.
The process further includes forming (at 706) gaps between ring-shaped rolling structures of the roller, the gaps to allow the stray build material to pass from the inner region to the cavities of the belt.
In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.
Filing Document | Filing Date | Country | Kind |
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PCT/US2016/028874 | 4/22/2016 | WO | 00 |