THREE-DIMENSIONAL PRINTING METHOD

Abstract

Disclosed is a three-dimensional printing method for instantly generating a needed molten raw material by way of a resistance heating function during three-dimensional printing. The method can realize three-dimensional printing of material having a high melting point and falls within the technical field of additive manufacturing. The method is characterized by applying a current through a solid raw material and a body to be printed; partially or fully heating the solid raw material located between a guiding device and said body to be printed into a molten state by way of resistance heating; and generating a molten raw material in a space located between the guiding device and the body to be printed. During the accumulation of the molten raw material, an area of the body to be printed and where the molten raw material is to be accumulated and/or is being accumulated is heated; or, the body to be printed is heated; or, the area of the body to be printed and where the molten raw material is to be accumulated and/or is being accumulated is heated, and the body to be printed is heated.

Claims

1. A three-dimensional printing method, which comprises main processes of placing a molten raw material in a forming area used by a three-dimensional printing apparatus, when cooled down, the previously molten raw material being converted into a printed workpiece, the molten raw material being accumulated on the basis of the printed workpiece until an object to be printed is formed, and the accumulated printed workpiece constituting the object to be printed, wherein: in the process of accumulating the molten raw materials, the position in which the molten raw material is placed is determined by the shape and structure of the object to be printed; the forming area used by the three-dimensional printing apparatus refers to a space used by the three-dimensional printing apparatus when printing the object; and during the three-dimensional printing process the molten raw material is obtained by heating a solid raw material, a guiding device is used to guide the movement of the solid raw material, and the molten raw material is a raw material in a molten or semi-molten state, characterized in that, applying a current through the solid raw material and the printed workpiece, heating the solid raw material located between the guiding device and the printed workpiece into a molten state by way of resistance heating, and generating the molten raw material in a space located between the guiding device and the printed workpiece, the form of the solid raw material is linear or rod-shaped, the molten raw material is at the front end of the solid raw material and adheres to the solid raw material, the position of the molten raw material is controlled by the processes of: the molten raw material is pushed toward the printed workpiece or the support platform and is far away from the guiding device by the moving caused by the solid raw material's outputting from the guiding device, and the accumulating position of the molten raw material is controlled by the relative moving between the solid raw material and the printed workpiece, wherein, in the process of accumulating the molten raw materials: heating the area of the printed workpiece where the molten raw material is about to be accumulated and/or is being accumulated, which is independent of the resistance heating generated by applying current through the solid raw material and the printed workpiece; the solid raw material is a conductive material.

2. The three-dimensional printing method according to claim 1, characterized in that, the area of the printed workpiece where the molten raw material is about to be accumulated is heated to generate a molten pool, which is independent of the resistance heating generated by the current applied through the solid raw material and the printed workpiece.

3. The three-dimensional printing method according to claim 1, characterized in that, the solid raw material located between the guiding device and the printed workpiece is partially heated into a molten state by way of resistance heating caused by the current applied through the solid raw material and the printed workpiece, and the molten raw material is generated in a space located between the guiding device and the printed workpiece.

4. The three-dimensional printing method according to claim 1, characterized in that, the solid raw material located between the guiding device and the printed workpiece is completely heated into a molten state by way of resistance heating caused by the current applied through the solid raw material and the printed workpiece, and the molten raw material is produced in a space located between the guiding device and the printed workpiece.

5. The three-dimensional printing method according to claim 1, characterized in that, the current is applied through the solid raw material and the printed workpiece, part or all of the solid raw material in contact with the printed workpiece is heated to a molten state or a semi-molten state by way of resistance heating, and the molten raw material is produced in the space between the solid raw material and the printed workpiece; and/or, the current is applied through the solid raw material and the printed workpiece, part or all of the solid raw material adjacent to the printed workpiece is heated to a molten state or a semi-molten state by way of resistance heating, and the molten raw material is produced in the space between the solid raw material and the printed workpiece; the solid raw material adjacent to the printed workpiece refers to the solid raw material adjoining to the molten raw material being accumulated.

6. The three-dimensional printing method according to claim 1, characterized in that, the printed workpiece is supported by a support platform, and the support platform is a device or structure for supporting the printed workpiece during the three-dimensional printing process.

7. (canceled)

8. The three-dimensional printing method according to claim 1, characterized in that, the heating at the area of the printed workpiece where the molten raw material is about to be accumulated and/or is being accumulated is caused by a method which comprises one or a combination of at least two of plasma heating, electrical arc heating, electromagnetic induction heating, resistance heating, laser heating, electron beam heating, and microwave heating.

9. The three-dimensional printing method according to claim 1, characterized in that, the main steps of the three-dimensional printing method include: Step S1: heating the part of the printed workpiece where the molten raw material is about to be accumulated; Step S2: outputting the solid raw material from the guiding device; Step S3: establishing an electrical connection between the solid raw material and the printed workpiece, that is, the current can flow through the solid raw material and the printed workpiece, which is a resistance connection, not a connection via an electrical arc; Step S4: applying current through the solid raw material and the printed workpiece, partially or completely heating the solid raw material between the guiding device and the printed workpiece into a molten state by way of resistance heating; Step S5: controlling a scanning position of the solid raw material on the printed workpiece by regulating the relative position between the guiding device and the printed workpiece, at the same time outputting the solid raw material from the guiding device; during this process, heating the area of the printed workpiece where the molten raw material is about to be accumulated and/or heating the area of the printed workpiece where the molten raw material is being accumulated, applying current through the solid raw material and the printed workpiece and performing resistance heating on the solid raw material to continuously produce the molten raw material; the guiding device contacting with the solid raw material and the printed workpiece, act as the electric interfaces for the current flowing through the solid raw material and the printed workpiece, or to apply current through an electrode which contacting with the solid raw material and the printed workpiece act as the electric interfaces.

10. The three-dimensional printing method according to claim 1, characterized in that, when there is no need to continue producing the molten raw material, or when the three-dimensional printing is suspended or stopped, the current is applied through the solid raw material and the printed workpiece, with the current intensity that is sufficient to fuse and break the molten raw material between the guiding device and the printed workpiece, or sufficient to fuse and break the molten raw material between the electrode contacting with the solid raw material and the printed workpiece.

Description

DESCRIPTION OF THE DRAWINGS

[0063] FIGS. 1 and 2 are schematic diagrams for describing the principle of a first specific embodiment of a three-dimensional printing method of the present invention, arrows D1 and D2 in FIG. 2 indicating the moving direction; and

[0064] FIG. 3 is a schematic diagram for describing the principle of a second specific embodiment of a three-dimensional printing method of the present invention, arrows D3, D4, and D5 in FIG. 3 indicating the moving direction.

EMBODIMENTS

[0065] Hereinafter, preferred specific embodiments of the present invention are listed and described in detail with reference to the accompanying drawings.

[0066] FIGS. 1 and 2 illustrate a first specific embodiment of a three-dimensional printing method of the present invention: a three-dimensional printing method, which mainly comprises the steps of placing a molten raw material in a forming area used by a three-dimensional printing apparatus, the molten raw material being converted into a printed workpiece (that is, printed workpiece I 1) when cooled down, the molten raw material being accumulated on the printed workpiece until an object to be printed is formed, and the accumulated printed workpiece constituting the object to be printed; wherein, in the process of accumulating the molten raw material, the position where the molten raw material is placed is determined by the shape and structure of the object to be printed (in other words, the three-dimensional printing apparatus controls the accumulation position of the molten raw material according to the computer model data corresponding to the object to be printed); the forming area used by the three-dimensional printing apparatus refers to a space used by the three-dimensional printing apparatus when printing the object; and during the three-dimensional printing process the molten raw material is obtained by heating a solid raw material, a guiding device is used to guide the movement of the solid raw material (i.e., solid raw material I 2), and the molten raw material is a raw material in a molten or semi-molten state,

[0067] the key is:

[0068] applying a current through the solid raw material and the printed workpiece (a heating current is generated through a circuit I 7), partially or completely heating the solid raw material located between the guiding device (i.e., guiding device I 6) and the printed workpiece (i.e., printed workpiece I 1) into a molten state by way of resistance heating, generating a molten raw material (i.e., melting raw material 4) in a space located between the guiding device and the printed workpiece; in this specific embodiment, the intensity of the applied current is an empirical value obtained through multiple tests;

[0069] wherein, in the process of accumulating the molten raw material:

[0070] heating the area of the printed workpiece where the molten raw material is about to be accumulated and where the molten raw material is being accumulated to produce a high temperature area 3 on the surface of the printed workpiece; the heating being independent of the above resistance heating generated by applying current through the solid raw material and the printed workpiece. The heating of the area of the printed workpiece where the molten raw material is about to be accumulated and where the molten raw material is being accumulated is electromagnetic induction heating in terms of the heating method: focusing the high-frequency alternating magnetic field onto the area where the molten raw material is about to be accumulated and where the molten raw material is being accumulated, and using the “skin effect” produced by the high-frequency alternating magnetic field in this area to produce a high-temperature layer (or even a molten layer) on the surface of this area.

[0071] The form of the used solid raw material is linear, and the solid raw material is a conductive material, i.e., a metal wire.

[0072] During the three-dimensional printing process, the printed workpiece is supported by a support platform (i.e., support platform I 11); the support platform is an apparatus used to support the printed workpiece during the three-dimensional printing process.

[0073] The position control processes of the molten raw material are as follows: movement caused by output of the solid raw material from the guiding device pushes the molten raw material away from the guiding device and toward the printed workpiece (in the direction shown by arrow D1); and the relative movement between the solid raw material and the printed workpiece (in the direction shown by arrow D2) controls the accumulating position of the molten raw material. The solid raw material moves with the guiding device (in the direction shown by arrow D2). When the moving speed of the solid raw material I 2 (in the direction shown by arrows D1 and D2, with the support platform I 11 as the reference) is fast enough (such as the speed is 300 mm/s), and at the same time the resistance heating is maintained to continuously produce the molten raw material, a molten raw material flow can be formed: as soon as the solid raw material I 2 enters the space between guiding device I 6 and printed workpiece I 1, it is heated and melted, and the produced molten raw material is immediately pushed to the printed workpiece I 1 and then accumulated; and since the solid raw material I 2 is constantly replenished and the guiding device I 6 is equipped with a heat dissipation structure (such as a water cooling channel), and the printed workpiece I 1 cannot react quickly enough due to its thermal conductivity to reduce the temperature of the melting raw material 4 to below the melting point, the continuous production and positional change of the melting raw material 4 is visually expressed as a molten raw material flow, however the boundary between solid raw material I 2 and the melting raw material 4 is still solid. This is also the main reason why the conductive materials with high melting point (such as tungsten metal) can be used in the present invention.

[0074] In the process of generating and accumulating the molten raw materials, the heating current applied through the printed workpiece I 1 and the solid raw material I 2 can heat and melt the parts of the high temperature area 3 on the printed workpiece surface that are in contact with the molten raw material (the temperature of the high temperature area 3 on the printed workpiece surface is controllable, and its temperature value and the applied current intensity may be empirical values obtained by many tests), and metallurgical welding may be realized between the raw material 5 accumulated on the printed workpiece and the printed workpiece I 1, i.e., realizing the high-strength connection. By controlling the intensity of the above-mentioned heating of the area of the printed workpiece where the molten raw material is about to be accumulated and where the molten raw material is being accumulated and the applied current intensity therefor, it is possible to control whether the connection between the raw material 5 accumulated on the printed workpiece and the printed workpiece I 1 is welding so as to control the connection strength; and in such areas where detachable supports need to be produced, high-strength connections are not required. The detachable support plays a role of supporting the printed parts in the three-dimensional printing technology, just like the scaffolding used in construction (the scaffolding is removed after it is built).

[0075] FIG. 3 illustrates a second specific embodiment of a three-dimensional printing method of the present invention.

[0076] The second specific embodiment comprises: using a plasma 9 to heat an area of the printed workpiece (that is, printed workpiece II 12) where the molten raw material is about to be accumulated, to form an area 10 heated by the plasma on the surface of the printed workpiece; and using a plasma nozzle 8 to guide jetting of the plasma 9 (in the direction shown by arrow D5) and control the jetting area. The printed workpiece II 12 is supported by a support platform II 16, and the support platform II 16 also is a heating platform (with a resistance heating component inside), which heats the entire printed workpiece II 12. The plasma nozzle 8 and the guiding device II 14 move synchronously (in the direction shown by arrow D4), and the solid raw material II 13 moves under the drive of the guiding device II 14 (in the direction shown by arrow D4). The solid raw material II 13 can be moved to the printed workpiece II 12 under the guidance of the guiding device II 14 (in the direction shown by arrow D3). The plasma nozzle 8 is connected to a position-drive mechanism (not shown in the figure); under the control of the position-driven structure the plasma nozzle 8 is always aimed at the area of the printed workpiece (i.e., printed workpiece II 12) where the molten raw material is about to be accumulated; and since the plasma nozzle 8 and the guiding device II 14 together move rapidly (for example, at a speed of 300 mm/s), when the area previously heated by the plasma 9 comes into contact with the molten raw material or solid raw material, this area still has the higher temperature than other areas not heated by the plasma 9 (the temperature of this area is mainly affected by the overall temperature of the printed workpiece II 12, the thermal conductivity of the material of the printed workpiece II 12, the distance between the said area and the plasma nozzle 8 in the direction indicated by arrow D4, the moving speed of the plasma nozzle 8, the temperature of the plasma 9, the heat capacity of the plasma 9 and other parameters, and the empirical values of these parameters can be obtained through multiple tests). The support platform II 16 has conductivity, and current applied through the solid raw material II 13 and the printed workpiece II 12 is generated by a circuit II 15. Heating the printed workpiece II 12 as a whole can reduce the energy required for heating the area where the molten raw material is about to be accumulated and where the molten raw material is being accumulated, thereby reducing system complexity and improving reliability.

[0077] The above embodiments are only preferred specific examples of the present invention, and are not intended to limit the scope of the present invention. The equivalent transformations and modifications made according to the contents of the claims and the description of the present invention still fall within the scope of the present invention.

LIST OF REFERENCE SIGNS

[0078] 1—printed workpiece I [0079] 2—solid raw material I [0080] 3—high temperature area on the printed workpiece surface [0081] 4—melting raw material [0082] 5—raw material accumulated on the printed workpiece [0083] 6—guiding device I [0084] 7—circuit I [0085] 8—plasma nozzle [0086] 9—plasma [0087] 10—area heated by the plasma on the surface of the printed workpiece [0088] 11—support platform I [0089] 12—printed workpiece II [0090] 13—solid raw material II [0091] 14—guiding device II [0092] 15—circuit II [0093] 16—support platform II

SUMMARY

[0094] The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed Description

[0095] In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.