Powder laying type metal 3D printer wind field

Abstract

The invention discloses an implementation method for uniformizing a wind field and neutralizing powder static electricity of a powder spreading type metal 3D printer. Comprising a main bin, the main bin, a draught fan, a filter and an ion propelling device form a closed cycle, and the ion propelling device is arranged at the height of a powder laying plane. The ion propulsion device includes a positive electrode, a negative electrode, and a high voltage power source. The high-voltage power supply generates an electric field through the positive electrode and the negative electrode to ionize gas, and gas ions generated after ionization are accelerated by the electric field to form ionic wind. And the ionic wind takes away ash on the powder spreading plane and neutralizes charges existing on the surface of the powder, so that powder agglomeration is prevented.

Description

1. Technical Field

[0001] The present invention belongs to the field of additive manufacturing (3D printing), and more precisely, belongs to the field of powder-spreading metal 3D printer equipment, and is used to simultaneously solve the problem of uniformity of the wind field inside the equipment and the problem of electrostatic agglomeration of powder. 2. Background technology

[0002] Problem 1 to be solved: Powder-spreading metal 3D printers, such as SLM metal 3D printers. It is necessary to use flowing inert gas to protect the sintering process from oxidation, and to promptly take away the smoke (mainly metal compounds) generated by the high-temperature sintering process, purify it through the filter element and recycle it to prevent it from depositing on the powder surface and the sintering surface. In order to stably take away the smoke, it is first necessary to obtain a uniform and stable wind field on the powder surface. However, the current technology is very difficult and costly to obtain a uniform wind field. There are two main points in the existing technology, but it is difficult to obtain a parallel, stable and adjustable wind field.

[0003] Typical unstable wind farm solution:

[0004] like Figure 1 As shown, the fan is deployed outside the main compartment and enters the main compartment through a pipe and a bell-shaped joint 3. When the circulating gas is ejected from the bell mouth, the flow velocity and pressure on the cross section are uncontrollable. The internationally accepted solution is to use a rectifier at the bell mouth. However, on the one hand, the rectifier cannot be completely uniform. On the other hand, the rectifier's adjustment of the flow field uniformity is also related to the flow velocity, which is easy to form vortices and make the flow field more turbulent. The essence of this uneven problem lies in the unreasonable distribution of the fan flow. Regardless of the type of mechanical fan, the flow field needs to be distributed through a rectifier, and the problem of uneven flow field cannot be fundamentally solved.

[0012] Problem 2 to be solved: In metal 3D printers that spread powder, static electricity caused by friction between electrical components and moving parts is inevitable. This static electricity will attract powder together to form agglomerates, making it difficult to spread powder and thus seriously affecting the printing quality, which is also known as the powder static electricity problem. The usual solution is to ground all metal parts of the equipment, but due to the effectiveness of grounding and other factors, this static electricity is difficult to completely eliminate. 3. Summary of the invention

[0013] The purpose of the present invention is to solve the problem of uneven wind field in powder-laying metal 3D printers. To this end, this solution completely abandons the mechanical fan solution and uses ion propulsion to achieve the wind field. It includes:

[0014] An ion power module.

[0015] Preferably, the ion power module is deployed inside or outside the powder-laying metal 3D printer or on one side of the powder-laying plane.

[0016] Preferably, the ion power module comprises a positive electrode, a negative electrode, and a high voltage power supply.

[0017] Preferably, the voltage of the high-voltage power supply is 10kV-100kV, the no-load power is ≤2W, the load current is ≤5A, and the average output current is less than or equal to 50mA.

[0018] Preferably, the voltage of the high-voltage power supply is regulated by the powder-laying metal 3D printer control system within a preferred range. The wind speed and air volume increase as the voltage increases and decrease as the voltage decreases, thereby achieving seamless adjustment according to the needs of the specific process.

[0019] Preferably, the positive electrode is connected to the positive electrode of a high voltage power supply.

[0020] Preferably, the negative electrode is connected to the negative electrode of a high voltage power supply.

[0021] Preferably, the lengths of the positive electrode and the negative electrode, as well as the voltage of the high-voltage power supply, are adjusted according to the size of the powder-laying plane, which is specifically determined by experiments. 4. Description of the drawings

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a typical solution for uneven wind field on the market. In the figure: 1 galvanometer, 2 main chamber, 3 bell-shaped joint, 3.1 rectifier, 4 powder chamber, 5 outlet bell-shaped joint, 6 fan, 7 filter.

[0024] Figure 2 The overall structure diagram of the present invention is shown in FIG. Figure 1 Corresponding. In the figure: 8 ion propulsion power modules, 71 throttle valves.

[0025] Figure 3 This is a detailed enlarged view of the ion propulsion power module of the present invention: 8. In the figure: 81 high voltage power supply, 82 negative electrode, 83 positive electrode, 84 wire, 85 wire.

[0026] Figure 4 The schematic diagram of the ion propulsion power module of the present invention is shown in FIG. 91 is a positive electrode, 92 is a negative electrode, 93 is positive ions after ionization, 94 is electrons, and 95 is a high voltage power supply.

[0027] Beneficial effects:

[0028] 1. There are no rotating parts or mechanical parts, the electric field is uniform, and the flow field formed is very stable and has no turbulence, which fully meets the requirements of powder metal 3. D The printer's need for wind farms;

[0029] 2. The generated ion wind can also eliminate the static electricity of powder. The principle is: the positive and negative charge airflow formed by the ion wind neutralizes the charge on the inner surface of the printer. When the powder surface is negatively charged, it will attract the positive charge in the airflow. When the powder surface is positively charged, it will attract the negative charge in the current, so that the static electricity on the powder surface is neutralized and the purpose of eliminating static electricity is achieved. 5. Specific implementation methods

[0030] The content of the present invention can be more easily understood by selecting the following detailed description of the preferred implementation method of the present invention and the embodiments included. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs. When there is a conflict, the definition in this specification shall prevail.

[0031] like Figure 2 As shown, the ion propulsion power module 8 is deployed at a height on the molding plane, replacing the horn-type rectifier 3 in the original solution.

[0032] A part of the airflow generated by the fan 7 enters the main compartment 2, and the other part is regulated by the throttle valve 71 and enters the ion propulsion power module 8. The flow rate of the throttle valve 71 is limited to less than 0.02 cubic meters per second.

[0033] like Figure 3 As shown, the ion propulsion power module 8 is composed of a positive electrode 82 and a negative electrode 83; the positive electrode 82 is connected to the positive electrode of the high-voltage power supply 81 through a wire 84, and the negative electrode 83 is connected to the negative electrode of the high-voltage power supply 81 through a wire 85.

[0034] The positive electrode 82 and the negative electrode 83 are made of oxygen-free copper.

[0035] The voltage of the power source 81 is 30 kV, and the distance L2 between the positive electrode 82 and the negative electrode 83 is 25 mm.

[0036] Its working principle is as follows Figure 4 As shown, under the action of the high voltage electric field, the electrons 94 of the gas molecules are stripped and flow to the positive electrode 91. The gas molecules lose their charge and become positively charged ions 93. Under the action of the electric field, the positive ions 93 move toward the negative electrode 92, forming an ion wind.

[0037] In the powder metal 3D printing system with argon as the protective gas, the generated ion wind speed V is about 1.2m / s.

[0038] When the gas is ionized, the gas passing through the throttle valve 71 will blow the gas mixed with electrons and positive ions toward the powder and the molding surface, neutralizing the static electricity carried by the powder and the warehouse body.

[0039] Since there are no mechanical parts or rotating parts in the entire system, and the electric field is evenly distributed between the positive electrode 82 and the negative electrode 83, a stable laminar ion wind is formed.

[0040] In order to form a more uniform and stable wind field, the positive electrode 82 can be designed into various shapes such as multi-segment combination, serrated, needle-shaped, etc. to meet the needs of different scenarios.

Claims

1. A method for achieving a uniform wind field and neutralizing powder static electricity in a powder-spreading metal 3D printer, characterized in that: It includes a main compartment, which forms a closed circulation loop with a fan, a filter, and an ion propulsion device. The ion propulsion device is deployed at the height of a powder laying plane.

2. The closed circulation loop according to claim 1, characterized in that: The fan outlet is divided into two paths, one of which is introduced into the main compartment, and the other is introduced into the ion propulsion device.

3. The ion propulsion device according to claim 2, characterized in that: Includes positive electrode, negative electrode, and high voltage power supply.

4. The ion propulsion device according to claim 3, characterized in that: The positive electrode and the negative electrode are made of high conductivity materials and are manufactured into suitable shapes according to actual conditions.

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