BEARING BASED LEVELING ASSEMBLY FOR THREE-DIMENSIONAL OBJECT PRINTING

Abstract

A three-dimensional object printer comprises a conveyor having a surface configured to convey a three-dimensional object in a first direction; and a leveling assembly configured to level a surface of the three-dimensional object as the conveyer conveys the three-dimensional object in the first direction, the leveling assembly comprising (i) a roller having a cylindrical shape, the roller having an outer surface that moves upon the surface of the three-dimensional object to level the surface of the three-dimensional object; and (ii) a guide device arranged between the roller and the planar surface of the conveyer, the device being configured to mechanically interact with the roller to maintain a constant distance between the outer surface of the roller and the planar surface of the conveyer.

Claims

1. A three-dimensional object printer comprising: a conveyor having a planar surface configured to convey a three-dimensional object in a first direction, the first direction being parallel to the planar surface; and a leveling assembly arranged along the conveyer and configured to level a surface of the three-dimensional object as the conveyer conveys the three-dimensional object in the first direction, the leveling assembly comprising: a roller having a cylindrical shape about a longitudinal axis and arranged in the second direction with respect to the planar surface of the conveyer, the roller being configured to rotate about the longitudinal axis, the longitudinal axis being parallel to the planar surface of the conveyer and perpendicular to the first direction, the roller having an outer surface that moves upon the surface of the three-dimensional object to level the surface of the three-dimensional object; and a guide device arranged between the roller and the planar surface of the conveyer, the device being configured to interact mechanically with the roller to maintain a constant distance between the outer surface of the roller and the planar surface of the conveyer.

2. The three-dimensional object printer of claim 1, the leveling assembly further comprising: an actuator configured to move the guide device in the second direction with respect to the surface of the conveyer to adjust the maintained distance between the outer surface of the roller and the planar surface of the conveyer.

3. The three-dimensional object printer of claim 1, the guide device comprising: a bearing, the bearing having a rotational axis that is parallel with the longitudinal axis of the roller, the bearing having an outer surface that moves against the outer surface of the roller as the roller rotates.

4. The three-dimensional object printer of claim 3, the bearing comprising: a first bearing and a second bearing, the first bearing being arranged at a first end of the roller, the second bearing being arranged at a second end of the roller.

5. The three-dimensional object printer of claim 4, the guide device further comprising: a member connected to the first bearing and connected to the second bearing, the member being configured to keep the first bearing in alignment with the second bearing.

6. The three-dimensional object printer of claim 2 further comprising: a controller operably connected to the actuator, the controller being configured to operate the actuator to move the guide device.

7. The three-dimensional object printer of claim 6, wherein the controller is configured to operate the actuator to move the bearing a predefined distance from the planar surface of the conveyer such that the three-dimensional object passes between the planar surface of the conveyer and the roller without making contact with the roller.

8. A leveling assembly for retrofitting a three-dimensional object printer having (i) a conveyor having a planar surface configured to convey a three-dimensional object in a first direction, the first direction being parallel to the planar surface, and (ii) a roller arranged along the conveyer and configured to level a surface of the three-dimensional object as the conveyer conveys the three-dimensional object in the first direction, the roller having a first end and a second end and a cylindrical shape about a longitudinal axis that is perpendicular to the first direction and parallel to the planar surface of the conveyer, the roller having an outer surface that moves upon the surface of the three-dimensional object to level the surface of the three-dimensional object as the object moves in the first direction, the leveling assembly comprising: a guide device configured to be arranged between the roller and the planar surface of the conveyer, the device being configured to interact mechanically with the roller to maintain a constant distance between the outer surface of the roller and the planar surface of the conveyer; and an actuator operatively connected to the guide device, the actuator being configured to adjust a distance between an upper surface of the guide device and the planar surface to position the guide device for removal of a portion from the surface of the three-dimensional object.

9. The leveling assembly of claim 8, wherein the actuator is further configured to move the guide device in the second direction with respect to the surface of the conveyer to adjust the maintained distance between the outer surface of the roller and the planar surface of the conveyer.

10. The leveling assembly of claim 8, the guide device comprising: a bearing, the bearing having a rotational axis that is parallel with the longitudinal axis of the roller, the bearing having an outer surface that moves against the outer surface of the roller as the roller rotates.

11. The leveling assembly of claim 10, the bearing comprising: a first bearing and a second bearing, the first bearing being arranged at a first end of the roller, the second bearing being arranged at a second end of the roller.

12. The leveling assembly of claim 11, the guide device further comprising: a member connected to the first bearing and connected to the second bearing, the member being configured to keep the first bearing in alignment with the second bearing.

13. The leveling assembly of claim 9 further comprising: a controller operably connected to the actuator, the controller being configured to operate the actuator to move the guide device.

14. The leveling assembly of claim 13, wherein the controller is configured to operate the actuator to move the bearing a predefined distance from the planar surface of the conveyer such that the three-dimensional object passes between the planar surface of the conveyer and the roller without making contact with the roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The foregoing aspects and other features of the method and device are explained in the following description, taken in connection with the accompanying drawings.

[0013] FIG. 1 shows a three-dimensional object printing system having a leveling assembly according to the disclosure.

[0014] FIG. 2 shows a controller and actuator for positioning a bearing of the leveling assembly.

[0015] FIG. 3 shows an alternative embodiment having a member that attaches to both bearings.

[0016] FIG. 4 shows a side view of the printing system of FIG. 1.

[0017] FIGS. 5A and 5B depict the operation of the leveling assembly.

[0018] FIG. 6 shows perspective view of a prior art three-dimensional object printing system.

[0019] FIG. 7 shows a side view of the prior art printing system of FIG. 6.

[0020] FIGS. 8A and 8B depict the ripple effect caused by run-out in the roller of the leveling assembly in the prior art printing system of FIG. 6.

DETAILED DESCRIPTION

[0021] For a general understanding of the environment for the three-dimensional object printing system disclosed herein as well as the details for the three-dimensional object printing system, reference is made to the drawings. In the drawings, like reference numerals designate like elements.

[0022] FIG. 1 shows a three-dimensional object printing system 400 according to the disclosure. Similar to the printing system 100, the printing system 400 includes a conveyer 404 having a substantially planar surface 412 upon which printed parts, such as the part 416 are placed. The conveyer 404 is configured to convey the part 416 in the conveying direction X, which is parallel to the surface 412 of the conveyer 404.

[0023] However, the printing system 400 differs from the system 100 because it includes a leveling assembly 424. The leveling assembly 424 includes a leveling roller 408 and at least one guide device. The roller 408 is similar to the roller 108 of the printing system 100. The roller 408 is arranged above the surface 412 of the conveyer 404 in the vertical direction Y, which is normal to the surface 412 of the conveyer 404. The roller 408 is generally cylindrical about a longitudinal axis that extends in the lateral direction Z, which is parallel to the surface 412 of the conveyer 404 and orthogonal to the conveying direction X. In one embodiment, the roller 408 is manufactured within one micron of variability in its straightness. However, the roller 408 has imperfect roundness that results in run-out, as described above with respect to the roller 108.

[0024] The leveling assembly 424 is designed to compensate for the imperfect roundness of the roller 408 without incurring the substantial costs of correcting the run-out in each roller 408. The guide device is arranged between the roller 408 and the surface 412 of the conveyer 404. The guide device is configured to interact mechanically with the roller 408 to maintain a constant distance between the outer surface of the roller 408 and the surface 412 of the conveyer 404. As shown in FIG. 1, the guide device comprises a pair of precision bearings 428. The bearings 428 have an outer surface that abuts a portion of the outer surface of the roller 408 that is closest to the surface 412 of the conveyer 404. The bearings 428 are held at a particular distance from the surface 412 of the conveyer 404 so the outer surface of the roller 408 is kept at a constant distance from the surface 412 of the conveyer 404. As the roller 408 rotates about its longitudinal axis on the bearings 428, the run out in the roller 408 pushes the roller away from the conveyer 404 when the diameter of the roller increases in the vertical Y direction and moves towards the conveyor when the diameter of the roller decreases in the vertical direction Y.

[0025] In some embodiments, the leveling assembly 424 further comprises at least one actuator connected to the bearings 428 and the actuator is configured to move the bearings 428 in the vertical direction Y to adjust the distance maintained between the outer surface of the roller 408 and the surface 412 of the conveyer 404. FIG. 2 shows one embodiment of an actuator 504 that is paired with one of the bearings 428. The actuator 504 is configured to move the bearing 428 up and down in the vertical direction Y to adjust the distance between the outer surface of the roller 408 and the surface 412 of the conveyer 404. A similar actuator 504 (not shown) is paired with the other of the bearings 428 on the opposite side of the conveyer 404.

[0026] In one embodiment, the printing system 400 further comprises a controller 508. The controller 508 is configured to operate the actuator 504 to adjust the distance between the outer surface of the roller 408 and the surface 412 of the conveyer 404. In some embodiments, the controller 508 is configured, after each layer of the part 416 is formed, to operate the actuator 504 to increase the distance between the outer surface of the roller 408 and the surface 412 of the conveyer 404. In some embodiments, the controller 508 is further configured, as required, to operate the actuator 504 to adjust the distance between the outer surface of the roller 408 and the surface 412 of the conveyer 404 to be sufficiently large to enable the part 416 to pass underneath the roller 408 without making contact with the roller 408. In some embodiments, the controller 508 is also configured to operate other parts of the printing system 400, such as the conveyer 404 or an ejector head that forms the layers of the part 416. In other embodiments, the controller 508 is a separate controller for the leveling assembly 424.

[0027] FIG. 3 shows an alternative embodiment in which the bearings 428 of the leveling assembly 424 are each attached to a U-shaped member 604. The member 604 is configured to keep the bearings 428 aligned with one another and is operated by actuator 608 to move the bearings 428. The actuator 608 operates to move the member 604 and the roller bearings 428 up and down in the vertical direction Y. In one embodiment, the actuator comprises a drive 612 that operates a lead screw 616. The lead screw 616 is operably connected to the member 604 such that rotations of the lead screw 616 cause the member 604 to move up or down in the vertical direction Y. The controller 508 is configured to operate the actuator 1032 in the same way described with respect to the previous embodiments.

[0028] FIG. 4 shows a side view of the printing system 400. As shown, the bearing 428 abuts the roller 408 at a point on the outer surface of the roller 408 that is closest to the surface 412 of the conveyer. The bearing 428 is held in place by the actuator 504 such that a distance D is maintained between the outer surface of the roller 408 and the surface 412 of the conveyer 404. As shown in FIG. 5A and FIG. 5B, the outer surface of the roller 408 moves upon the upper surface 420 of the part 416 as the conveyer 404 feeds the part 416 in the conveying direction X. As the roller 408 rotates, the bearing 428 also rotates and enables the run-out in the roller 408 to move the roller away from and towards the surface 412 of the conveyer 404 in the vertical direction Y depending on the increase and decrease in the diameter of the roller, respectively. In this way, the distance D between the outer surface of the roller 408 and the surface 412 of the conveyer 404 remains constant, regardless of the rotational position of the roller 408. As a result, the leveling assembly 424 flattens the surface 420 of the part 416 without the rippling effect that would otherwise be caused by the run-out in the roller 408.

[0029] It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems, applications or methods. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art, which are also intended to be encompassed by the following claims.