DOCTOR BLADE UNIT FOR AN ADDITIVE MANUFACTURING SYSTEM HAVING A PULVEROUS STARTING MATERIAL

Abstract

The present invention relates to a doctor blade unit for an additive manufacturing system having a pulverous starting material. By means of the doctor blade unit according to the invention, improved linearity of the doctor blade and parallelism with respect to the build plane are achieved. The doctor blade is suspended on a crossmember by means of adjustable fastening elements, and the crossmember in turn is fastened, on one side by means of a fixed bearing and on the other side by means of a floating bearing, to a guide support.

Claims

1. A doctor blade unit for an additive manufacturing system with a pulverous starting material, comprising a doctor blade (1) and a suspension system (2) which is to be mounted in a horizontally movable manner in the additive manufacturing system, characterized in that the suspension system (2) comprises a crossmember (3) which is mounted on the one side in a locating bearing (4) and on the other side in a floating bearing (5), the crossmember (3) is connected via the locating bearing (4) and the floating bearing (5) in each case to a guide bracket (6), and the doctor blade (1) is fastened in a suspended manner below the crossmember (3) via a multiplicity of fastening means (7) along its length, the fastening means (7) permitting a spacing adjustment between the doctor blade (1) and the crossmember (3) for the parallel orientation of the doctor blade (1) with respect to a construction level of the additive manufacturing system.

2. The doctor blade unit as claimed in claim 1, characterized in that the doctor blade (1) comprises a single blade, double blade or multiple blade.

3. The doctor blade unit as claimed in claim 1, characterized in that the guide brackets (6) are suitable for guidance with torque rigidity in the additive manufacturing system.

4. The doctor blade unit as claimed in claim 1, characterized in that the crossmember (3) is configured as a hollow body.

5. The doctor blade unit as claimed in claim 1, characterized in that the crossmember (3) has a rectangular or oval cross section.

6. The doctor blade unit as claimed in claim 1, characterized in that the locating bearing (4) encloses the crossmember (3) on its periphery on at least two sides, and prevents a movement of the crossmember (3) relative to the locating bearing (4) in all three spatial directions.

7. The doctor blade unit as claimed in claim 1, characterized in that a centering pin is attached to the inner periphery of the locating bearing (4), which centering pin is in positively locking engagement with a corresponding bore in the crossmember (3).

8. The doctor blade unit as claimed in claim 1, characterized in that the floating bearing (5) encloses the crossmember (3) on its periphery with sliding elements in such a way that a movement of the crossmember (3) relative to the floating bearing (5) along its longitudinal axis is made possible, while a movement in the two spatial directions which are perpendicular with respect thereto is prevented.

9. The doctor blade unit as claimed in claim 1, characterized in that the doctor blade (1) has a length of from 0.1 to 5 m.

10. The doctor blade unit as claimed in claim 1, characterized in that the parallelism deviation ΔP, defined as the difference between the greatest and smallest spacing between the doctor blade (1) and the construction level, is from 1 to 50 μm.

11. The doctor blade unit as claimed in claim 1, characterized in that the suspension system (2) has from 3 to 30, fastening means (7) per meter of doctor blade length.

12. The doctor blade unit as claimed in claim 1, characterized in that, during running operation of the additive manufacturing system, a change in the spacing of the doctor blade (1) from the crossmember (3) is possible by means of electromechanical and/or hydraulic actuators which act on the fastening means (7).

13. The doctor blade unit as claimed in claim 1, characterized in that the fastening means (7) are screwed bolts.

14. The doctor blade unit as claimed in claim 2, characterized in that the guide brackets (6) are suitable for guidance with torque rigidity in the additive manufacturing system.

15. The doctor blade unit as claimed in claim 14, characterized in that the crossmember (3) is configured as a hollow body.

16. The doctor blade unit as claimed in claim 9, wherein the doctor blade (1) has a length of from 0.3 to 3 m.

17. The doctor blade unit as claimed in claim 10, wherein the parallelism deviation ΔP is from from 10 to 25 μm.

18. The doctor blade unit as claimed in claim 11, wherein the suspension system (2) has from 3 to 10 fastening means (7) per meter of doctor blade length.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0029] FIG. 1 is a lateral sectional view of the doctor blade unit.

[0030] FIG. 2 is a perspective view of the doctor blade unit as viewed from the locating bearing side.

[0031] FIG. 3 is a perspective view of the doctor blade unit as viewed from the floating bearing side.

[0032] FIG. 4 is a perspective sectional view of the doctor blade unit with a section through a fastening means.

[0033] FIG. 5 is an enlarged detail from FIG. 4 which shows the lower region of the fastening means and the doctor blade.

DESCRIPTION OF THE FIGURES

[0034] The figures show merely one preferred design variant as an example for the invention. They are therefore not to be understood as restrictive.

[0035] FIG. 1 shows a lateral sectional view of a doctor blade unit according to the invention which is shown perspectively once again in FIG. 2 and FIG. 3. That design variant of the doctor blade unit which is shown in the figures is equipped with a doctor blade (1) with a double blade. The suspension system (2) comprises the crossmember (3) which, in the figure, is mounted on the left-hand side in the locating bearing (4) and on the right-hand side in the floating bearing (5) which are in turn connected in each case to a guide bracket (6). In this example, the doctor blade (1) is fastened to the crossmember (3) by way of seven fastening means (7) in the form of bolts with terminal threads and associated nuts. The length of the doctor blade (1) is 2 m. Accordingly, the doctor blade suspension system has 3.5 fastening means per meter of doctor blade length. The parallelism deviation ΔP which was achieved in this way was 10 μm.

[0036] The crossmember (3) supports its own weight and the mechanical load of the doctor blade (1). Its deflection can be compensated for via the fastening means (7), with the result that the doctor blade (1) which is suspended below it can be oriented rectilinearly and parallel to the construction level. As can be seen in FIGS. 2 and 3, the crossmember (3) is configured in this example as a tubular hollow body with a rectangular cross-sectional area and rounded edges. The guide brackets (6) are provided, for guidance with torque rigidity, with in each case two rail receptacles (8) which can be brought into engagement with rails with a substantially trapezoidal cross section in the manner of a dovetail connection. These rails are attached on the side of the construction container to the working surface. In this way, a distortion-free movement of the doctor blade unit over the construction level in order to level the applied powder is ensured.

[0037] As can be seen in FIG. 3, the floating bearing (5) is formed here by means of four sliding elements (9) which surround the crossmember (3). An expansion of the crossmember (3) in its longitudinal axis is therefore possible. The crossmember (3) is held rigidly on the locating bearing side, but can expand in the direction of the floating bearing side and can slide through the floating bearing (5), with the result that no constraint forces are introduced into the crossmember (3).

[0038] In FIG. 4 and FIG. 5, the region around a fastening means (7) is depicted on an enlarged scale in a sectional illustration. In the example which is shown, the bolts of the fastening means (7) run in a guide sleeve in the interior of the crossmember (3). The bent-over regions specify the maximum actuating travel for the adjustment of the blades (10). The two blades (10) are fastened below a solid central block (11) so as to be symmetrically centered in the middle. The fastening takes place in corresponding cutouts of the solid central block (11) via horizontal bolts, to which the blades (10) are fastened by way of spacer elements so as to be separated from one another. To the sides of this, the two pre-wipers (12) are attached to the outer sides of the central block (11).

[0039] A laser sensor system can be attached, for example, to the guide brackets (6) for active control of the doctor blade unit (not shown in the figures), which laser sensor system monitors linearity and parallelism of the doctor blade (1). The information obtained in this way can then be used for re-adjustment, for example, via electric actuating motors which drive the nuts, or piezoelectric elements.

LIST OF DESIGNATIONS

[0040] 1 Doctor blade

[0041] 2 Suspension system

[0042] 3 Crossmember

[0043] 4 Locating bearing

[0044] 5 Floating bearing

[0045] 6 Guide bracket

[0046] 7 Fastening means

[0047] 8 Rail receptacle

[0048] 9 Sliding element

[0049] 10 Blade

[0050] 11 Central block

[0051] 12 Pre-wiper