CN107116218A - A kind of use low-melting alloy is easy to the method that metal 3D printing removes support - Google Patents

Abstract

It is easy to the method that metal 3D printing removes support the invention discloses a kind of use low-melting alloy, using double nozzle printing systems, main jet head supply subject material, main component for printed product, secondary shower nozzle supplies low melting point alloy, for the support member of printed product, when being heat-treated after finished product printing shaping, backing material is melted.Present invention can apply to the 3D printing method of direct metal fusing, low-melting alloy auxiliary supporting material can be removed while Technology for Heating Processing is carried out, therefore relative to original processing in whole process, new process procedure is not increased, it can be saved the plenty of time compared to other post processing modes, use manpower and material resources sparingly cost, and can obtain more preferable surface quality.Meanwhile, the low-melting alloy after fusing can more meet the principle of green manufacturing with recycling.

Description

A method to facilitate support removal in metal 3D printing using low melting point alloys

technical field

The invention relates to a metal 3D printing technology, in particular to a method for removing supporting materials in the later stage of metal 3D printing.

Background technique

3D printing technology has outstanding advantages in the manufacture of workpieces with complex shapes through the principle of layer-by-layer superposition. The methods for 3D printing of metal components can be divided into two types, direct energy deposition and powder bed fusion. Among them, the direct energy deposition method uses the nozzle to supply powder or wire, and the energy of the laser or electron beam is used at the nozzle to form The molten pool is directly cladding the raw materials, and stacking them layer by layer according to the predetermined path to obtain the formed metal. Compared with the powder bed fusion type, the direct energy deposition type has a higher printing speed, and can realize simultaneous printing of multiple materials when using a multi-nozzle supply system, so it has a wide range of application prospects.

However, the direct energy deposition method also has major defects, because it is based on the principle of layer-by-layer superposition. Compared with the powder bed fusion method, the overhang angle that can be achieved when printing hollow or overhanging structures is smaller, and it is prone to collapse. At this time, adding support materials is an effective means. But the removal of support material after printing is often undesired. The support of plastic or other polymer material products can be removed with tools such as pliers because of its low hardness, or use soluble materials as supports, and the support materials will be dissolved after the workpiece is soaked in the solution after printing. However, in the 3D printing process of metal materials, it is time-consuming to remove the support material with pliers, the removal effect is not ideal, and it needs to be polished later, and so far no water-soluble metal can be used as an auxiliary support material.

Because the removal of support materials cannot be handled well, when printing overhanging structures with large overhang angles, tiltable worktables, five-axis platforms or robotic arms are generally used to increase the upper limit of the maximum overhang angle that can be achieved, but compared with three-coordinate In this way, complex manual path planning needs to be added, and the cost is high.

Owen J.Hildreth and others used low-carbon steel as a support material when printing stainless steel materials, and used electrochemical corrosion to dissolve the support material. The results were published in the journal "Dissolvable Metal Supports for 3D Direct Metal Printing" article. However, this method needs to select appropriate auxiliary materials and dissolving agents, the operation is more complicated, and it still takes a long time, and the more support materials are used in printing, the longer the dissolution time will be. In addition, support materials and solvents cannot be recycled, which is not in line with the concept of green manufacturing.

Contents of the invention

The purpose of the present invention is to provide a simpler and quicker method for removing auxiliary supports in the later stage of direct energy deposition metal 3D printing, which can remove supports without increasing the process steps, and realize the recycling of support materials.

The technical scheme that the present invention adopts is as follows:

A method of using low-melting-point alloys to facilitate the removal of supports in metal 3D printing. A dual-nozzle printing system is adopted. The main nozzle supplies the main material for printing the main components of the product, and the sub-nozzle supplies low-melting point alloy materials for printing the support of the product. , when the heat treatment is carried out after the finished product is printed and formed, the support is melted.

Further, before printing, first use the host computer software to add auxiliary supports according to the structure of the workpiece to be formed, and then generate slice data including the printing path of each layer, and upload it to the printer.

Further, the printer automatically executes the predetermined path and switches the required nozzles according to the slicing data, moves the main nozzle when printing the main material, and moves the auxiliary nozzle when printing the supporting material; layers are melted and solidified to complete the rough production.

Furthermore, due to the rapid cooling of metals during the 3D printing process, residual stress will be generated, so heat treatment is usually required. The biggest feature of low-melting point alloys is their low melting point (below 232°C). Different metal materials have different heat treatment temperatures, but they are much higher than this temperature. Therefore, they can be melted and removed while heat-treating the finished product. Lose. The melting point of the support material used is lower than the heat treatment temperature of the workpiece during heat treatment.

Further, the selection of the supporting material is based on the main material, and it is required that the melting point of the supporting material is lower than that of the main material.

Further, the support material adopts low melting point alloy.

Furthermore, after the low-melting point alloy is melted, it is collected in a container. Since the melting process only undergoes physical changes and the chemical properties of the material do not change, it can be recycled to remanufacture powder or wire raw materials to realize material reuse.

The beneficial effect that the present invention can realize:

The invention can be applied to the 3D printing method of direct metal melting, and the low-melting point alloy auxiliary support material can be removed while performing the heat treatment process. Therefore, compared with the original process, no new process links are added in the whole process. Other post-processing methods can save a lot of time, save manpower and material costs, and can obtain better surface quality. At the same time, the melted low melting point alloy can be recycled and reused, which is more in line with the principle of green manufacturing.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application, and do not constitute improper limitations to the present application.

Figure 1 Schematic diagram of the suspension structure;

Fig. 2 schematic diagram of support structure;

In the figure: 1 workpiece, 2 low melting point alloy auxiliary support, 3 substrate.

detailed description

It should be pointed out that the following detailed descriptions are all exemplary and are intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

The method disclosed in the present invention uses a low-melting-point alloy to facilitate metal 3D printing to remove supports. A dual-nozzle printing system is adopted. The main nozzle supplies the main body material for printing the main components of the product, and the sub-nozzle supplies the low-melting point alloy material for printing the product. The support member melts the support material during heat treatment after the finished product is printed and formed; specifically, as shown in Figures 1 and 2, the workpiece 1 and the low-melting point alloy auxiliary support are formed on the substrate 3, and the workpiece 1 is assisted by the low-melting point alloy. Support 2 support, in the subsequent process, the low melting point alloy auxiliary support 2 will be melted; the specific process is as follows:

1. Before printing, first use the host computer software to add auxiliary supports according to the structure of the workpiece to be formed, and then generate slice data including the printing path of each layer and upload it to the printer.

2. According to the slicing data, the printer automatically executes the predetermined path and switches the required nozzles, moves the main nozzle when printing the main material, and moves the auxiliary nozzle when printing the supporting material; layers are melted and solidified to complete the rough production.

3. Due to the rapid cooling of metal during the 3D printing process, residual stress will be generated, so heat treatment is usually required. The biggest feature of low melting point alloys is their low melting point (below 232°C). Different metal materials have different heat treatment temperatures, but they are much higher than this temperature. Therefore, they can be melted and removed while heat treating the finished product. Lose.

4. Recycling and reuse of low melting point alloys. After the low-melting point alloy is melted, it is collected in a container. Since the melting process only undergoes physical changes and the chemical properties of the material have not changed, it can be recycled to remanufacture powder or wire raw materials to realize material reuse.

The following is an example of printing a stainless steel arched main body workpiece and using a 200°C bismuth-tin low-melting point alloy as an auxiliary support. The steps of the present invention are as follows:

1. Prepare 316L stainless steel and bismuth-tin low-melting point alloy powder, equip 316L stainless steel into the main nozzle system, and equip bismuth-tin low-melting point alloy powder into the auxiliary nozzle supply system.

2. Upload the workpiece model to the host computer, complete the slicing, import the slicing data into the printer, and start printing.

3. After printing, wrap the supported workpiece with tin foil and put it into the heating furnace for heat treatment, and place it in a reasonable position so that the low-melting point alloy can flow down and collect naturally after melting; set the heating temperature for heat treatment to 600°C, and the holding time for 2 hours; start heat treatment.

4. After the heat treatment, take out the workpiece, separate the workpiece and the substrate, and collect it in a container after the low-melting point alloy is melted. Since only physical changes occur during the melting process, the chemical properties of the material have not changed, so the bismuth-tin low-melting point alloy can be recycled and remanufactured Powder or wire raw materials to realize material reuse.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (7)

1. a kind of use low-melting alloy is easy to the method that metal 3D printing removes support, it is characterised in that beaten using double shower nozzles Print system, main jet head supply subject material, for the main component of printed product, secondary shower nozzle supplies low melting point alloy, uses In the support member of printed product, when being heat-treated after finished product printing shaping, backing material is melted.

2. it is easy to the method that metal 3D printing removes support using low-melting alloy as claimed in claim 1, it is characterised in that Before the printing, first by upper computer software, Auxiliary support is added according to the structure of workpiece to be formed, then generation is comprising every The slice of data of one layer of printing path, and upload on printer.

3. it is easy to the method that metal 3D printing removes support using low-melting alloy as claimed in claim 1, it is characterised in that Printer is according to slice of data, and the automatic shower nozzle performed needed for predefined paths and switching moves main jet in type body material Head, the prismatic pair shower nozzle when printing backing material；Melt layer by layer and solidify completion blank and make.

4. it is easy to the method that metal 3D printing removes support using low-melting alloy as claimed in claim 1, it is characterised in that The fusing point of the backing material of use is less than heat treatment temperature of the workpiece when being heat-treated.

5. it is easy to the method that metal 3D printing removes support using low-melting alloy as claimed in claim 1, it is characterised in that The selection of described backing material is selected according to described material of main part, it is desirable to which the fusing point of backing material is less than main body material Material.

6. it is easy to the method that metal 3D printing removes support using low-melting alloy as claimed in claim 1, it is characterised in that Described backing material uses low-melting alloy.

7. it is easy to the method that metal 3D printing removes support using low-melting alloy as claimed in claim 6, it is characterised in that Described low-melting alloy uses container collection after being melted down, and powder or wire feedstock are remanufactured after recovery, realizes that material is sharp again With.