Apparatus for forming 3D objects

Abstract

An apparatus for forming 3D objects from metallic powder, includes a delivery mechanism adapted to emit a flow of metallic powder at sufficiently high velocity to enable it to form a solid mass on a substrate; and a positioning mechanism adapted to set or adjust the distance and/or angle between the delivery mechanism and the substrate as powder builds up on the substrate. A control system is adapted to receive measured geometry data representing the state of the object as it builds and to control adjustment of the positioning means in response to that data for accurate formation of the object.

Claims

1. An apparatus for forming 3D objects from a metallic powder comprising: a delivery mechanism including a cold spray nozzle, the cold spray nozzle configured to emit a beam of metallic powder at a velocity to enable the metallic powder to form a solid mass on a substrate; a positioning mechanism including a robotic arm including a five axis computer numerical controlled (CNC) frame or six axis industrial arm, the robotic arm securing and moving the substrate with respect to the delivery mechanism, so as to set or adjust a distance or an angle between the delivery mechanism and the substrate as the metallic powder builds up on the substrate; a control system including a computerized system to send control signals to the delivery mechanism and the positioning mechanism dependent on a 3D object to be formed, the control system configured to cause the positioning mechanism to continuously reorient and maintain a perpendicular angle of attack of the beam of the metallic powder as the 3D object forms from the metallic powder, wherein a function of defining a geometry of the 3D object is moved entirely to the control system such that the five axis CNC frame or the six axis industrial arm produces a motion in accordance with the geometry of the 3D object unconstrained by a geometry of the delivery mechanism and unconstrained by a geometry of the positioning mechanism.

2. The apparatus according to claim 1, wherein the metallic powder moves from the delivery mechanism to the substrate at a speed of 200 m/s to 2000 m/s.

3. The apparatus according to claim 1, wherein the metallic powder comprises a pure metal powder or an alloyed metal powder, atomized to an average size of between 5 and 50 microns in diameter.

4. The apparatus according to claim 1, wherein the metallic powder is at a temperature of between 0° C. and 500° C.

5. The apparatus according to claim 1, wherein the positioning mechanism maintains or adjusts a vertical and a horizontal spacing between the delivery mechanism and the substrate.

6. The apparatus according to claim 1, wherein the positioning mechanism maintains or adjusts an angular relationship between the delivery mechanism and the substrate in at least two axes.

7. The apparatus according to claim 1, wherein the robotic arm secures and moves the substrate with respect to the delivery mechanism such that the 3D object is formed by applying a sequence of layers, wherein each layer of the sequence of layers is formed of the metallic powder.

8. The apparatus according to claim 1, wherein the positioning mechanism further includes a gripping mechanism to grip the substrate.

9. The apparatus according to claim 1, wherein the computerized system sends control signals to the delivery mechanism and the positioning mechanism dependent on the 3D object being formed.

10. The apparatus according to claim 1, further comprising a housing disposed around the cold spray nozzle and the robotic arm prevents or minimizes egress of the metallic powder from the apparatus.

11. The apparatus according to claim 1, further comprising a 3D scanner to provide geometry data to the control system and, based on the geometry data, the control system causes the delivery mechanism and the positioning mechanism to adjust for accurate formation of the 3D object.

12. The apparatus according to claim 1, wherein the positioning mechanism further includes a substrate gripper which facilitates automated ejection of the 3D object when complete.

13. The apparatus according to claim 1, wherein the positioning mechanism further includes a screw or a belt driven axes mounted on linear guide rails, mounted either to the substrate or to the delivery mechanism, one or the other being held stationary, or where both the substrate and the delivery mechanism are mounted to separate axes.

14. The apparatus according to claim 1, further comprising a 3D scanner located proximate to the robotic arm such that during a time of not emitting the beam of metallic powder and not building up the metallic powder on the substrate secured on the robotic arm, the 3D scanner scans the 3D object to determine geometry data of the 3D object, and provides the geometry data to the control system and, based on the geometry data, the control system causing the delivery mechanism and the positioning mechanism to adjust for accurate formation of the 3D object.

15. The apparatus according to claim 1, wherein the robotic arm is a sole robotic arm including a sole five axis computer numerical controlled (CNC) frame or a sole six axis industrial arm, and wherein the function of defining the geometry of the 3D object is moved entirely to the control system such that the sole five axis CNC frame or the sole six axis industrial arm produces the motion in accordance with the geometry of the 3D object unconstrained by the geometry of the delivery mechanism and unconstrained by the geometry of the positioning mechanism.

Description

DRAWINGS

(1) Some preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, of which:

(2) FIG. 1 is an isometric view of a 3D printer;

(3) FIG. 2 is an isometric view showing certain internal parts of the printer;

(4) FIG. 3 is an isometric view showing detail of some parts of the printer; and

(5) FIG. 4 illustrates the manner in which an object may be formed by way of the printer.

DETAILED DESCRIPTION

(6) With reference to FIGS. 1-3, and particularly FIG. 3, the 3D printer 1 has a robotic arm 2 having a grip 3 for holding a substrate (not shown), and a spray nozzle 4. When the printer is in use a substrate is held by the grip 3 and a high velocity flow of heated pressurised air is emitted from the nozzle 4. A feeder feeds metallic powder to the air so that it also leaves the nozzle at high velocity and contacts the substrate. The arm 2 is adjustable so that the metallic powder moves in a vector of desired distance and angle so that it contacts the substrate in a manner suited to forming a desired product. As layers of the powder build up on the substrate the arm 2 reorients to maintain or adjust the desired distance and angle to the substrate.

(7) Referring to FIG. 1, the printer is housed within an easily managed enclosure 5. FIG. 2 illustrates the printer without the enclosure, and in particular within a build chamber 6. The build chamber supports a computerised system with an interface 7 for setting and providing manually generated or automatic computerised control commands to the robotic arm 2 and spray nozzle 4. The chamber 6 has a window 8 for conveniently viewing the printer when in use and an upper vent 9 to allow for escape of hot air.

(8) The computerised system may be adapted to interpret CAD drawings and use these to determine the type and number of control signals sent to the robotic arm 2 and spray nozzle 4.

(9) FIG. 4 schematically illustrates a substrate 10 on which a cylinder has been formed about an axis 6. The cylinder has been created in powder deposition steps or layers 11-15. As illustrated, the cylinder has not been built in a directly linear manner by rather in an ‘inflated’ manner, where each layer combines to produce the overall linear vertical dimension.

(10) The 3D printer is preferably formed to work at high speed and so that it can print metallic objects accurately from the powder with minimal restrictions in terms of the geometry of the objects.

(11) Preferably the robotic arm 2 causes a beam of the metal powder to moves across the surface of the substrate so that the beam remains substantially perpendicular to its point of contact of the substrate or a part formed on the substrate. This is enabled by the control functions of the printer's computerised system. The printer also enables the angle of the beam to be reoriented to less than perpendicular if need be, for example in order to form the desired 3D shape.

(12) In some embodiments of the invention the robotic arm 2 may comprise a five axis CNC frame or a six axis industrial arm. The selection of one or the other may depend on whether speed or accuracy is the most important consideration.

(13) In a preferred embodiment the build chamber 6 serves to physically contain excess powder to enable it to be collected and reused or recycled. The chamber 6 also keeps powder away from nearby equipment that can be damaged by exposure to the powder.

(14) In some embodiments of the invention the amount of excess powder is sensed and control parameters adjusted to reduce it, and therefore the risk of associated hazards.

(15) In some embodiments of the invention the printer has a 3D surface scanner within the build chamber 6. This is preferably located within reach of the robotic arm 2 and allows the printer to check the build level of an object during powder deposition breaks.

(16) In preferred embodiments of the invention it is desirable for the substrate or spray nozzle 4, or both, to be attached to a motion control system that can continuously reorient and maintain the angle of attack of the beam of powder generally perpendicular. In addition, a sophisticated digital control system may process a targeted 3D object geometry and generate appropriate tool paths that facilitate deposition to result in a 3D item that best matches the targeted geometry.

(17) While some preferred embodiments have been described by way of example it should appreciated that modifications and improvements can occur without departing from the scope of the invention.