CN103752825B - Utilize the device and method of metal melting deposition formation thin-walled workpiece - Google Patents

Abstract

The invention discloses and a kind ofly utilize the device and method of metal melting deposition formation thin-walled workpiece: comprise metal wire material and wire feed running roller, nozzle does x-y plane motion according to the cross section profile information of thin-walled workpiece, extrude simultaneously and control molten metal fluid flow, the metal liquid of melting is deposited on substrate equably, thin-walled parts cross section profile is formed after quick cooling, after one formable layer completes, substrate declines the height of a cross-sectional layers, carry out the deposition of lower one deck again, circulation like this, finally obtain the product prototype of metal thin-wall structural member, there is process flexibility high, constant product quality, heat affected area is little, workpiece thermal deformation is little, the advantage that following process amount is little, effectively improve manufacture efficiency and the performance of thin-walled workpiece, and greatly reduce manufacturing cost, improve the possibility that metal melting deposition process carries out producing in batches.

Description

Apparatus and method for forming thin-walled structural parts by metal fusion deposition

technical field

The invention relates to the field of rapid prototyping of metal thin-walled structural parts, in particular to a device and method for manufacturing thin-walled structural parts by using a metal fusion deposition method (FDM).

Background technique

Rapid prototyping technology is a high-tech emerging in the late 1980s, which integrates CAD/CAM, numerical control and material science technologies. The basic idea is: using layered software, the three-dimensional solid model established by CAD is divided into a series of thin section layers, and the forming system adopts bonding (sintering), polymerization or chemical reaction according to the two-dimensional data formed by each section layer. By means of such means as liquid (or bonded solid) materials are selectively solidified layer by layer, so as to quickly accumulate solid models. At present, more mature rapid prototyping processes include: stereolithography (SL), laminated entity manufacturing (LOM), selective laser sintering (SLS), and fused deposition modeling (FDM). Among them, FDM is a fast, safe and cheap rapid prototyping process, which has the advantages of easy operation, non-toxic and tasteless. Since this process has the above-mentioned remarkable advantages, it has developed extremely rapidly. FDM systems currently account for about 30% of the installed rapid prototyping systems worldwide.

So far, most of the thin-walled parts are the key parts of the product. Aerospace products generally require large structural size, light weight, and high precision, so there are more thin-walled parts. For example, the wing is a typical thin-walled part. At present, many thin-walled parts with high precision requirements in China are mostly completed by traditional turning, milling, planing, and grinding. In foreign countries, ultrasonic vibration cutting and high-speed cutting technologies are used for manufacturing. However, these methods are prone to deformation during manufacturing, and it is difficult to meet the accuracy requirements, which seriously affects product quality. Therefore, the rapid and high-precision processing of thin-walled parts is still a major problem in mechanical manufacturing. In addition, in the design and manufacture of airfoils, in order to reduce weight, it is common to use foam plastics or different types of honeycomb as the core material of the sandwich structure, but such a structure also increases the processing steps and time.

The materials currently used in the fused deposition method are mainly wires or powders of paraffin, plastics, ceramics, etc. In terms of fuse wire, the main materials are ABS, elastomer, cast wax and polycool thermoplastic. Compared with the pure aluminum block, the tensile strength of the parts obtained by the University of California, fused deposition with metal aluminum is increased by 30%, the hardness is increased by 100%, and the microstructure of the parts is significantly refined. However, at present, the use of fused deposition method (FDM) to manufacture thin-walled structural parts, especially the method of using metal wires as raw materials, has not been reported.

Contents of the invention

The object of the present invention is to provide a device and method for forming thin-walled structural parts by metal fusion deposition.

In order to achieve the above object, the present invention adopts the following technical solutions.

A device for forming thin-walled structural parts by metal fused deposition, the device for forming thin-walled structural parts includes a substrate and a metal fused deposition module, the metal fused deposition module includes a bracket, a threaded pipe arranged on the bracket, and a threaded tube arranged on the The heating block on the pipe and the heating pipe arranged in the heating block, the outlet end of the threaded pipe is provided with a nozzle opposite to the substrate, and the inlet end of the threaded pipe is provided with a wire feeding mechanism.

The surface of the substrate is flat, and the substrate can be continuously heated.

The metal fused deposition module is arranged above the substrate, the metal fused deposition module can move horizontally, and the substrate can be raised and lowered.

The substrate and the metal fused deposition module are arranged in a protective cover filled with protective gas, and the cross-sectional profile of the thin-walled structural part is formed in the environment filled with protective gas.

The device for forming thin-walled structural parts also includes a pre-heating device for forming a uniform temperature field between the outlet of the nozzle and the substrate.

The above-mentioned method for forming a thin-walled structural member using a device for forming a thin-walled structural member by metal fusion deposition includes the following steps:

1) Use the heating tube to heat up the heating block to the set temperature;

2) After step 1), the metal wire is used as the forming material, and the wire feeding mechanism is used to transport the metal wire from the inlet of the threaded pipe to the nozzle. During the transportation, the metal wire is transformed into melting by the temperature of the heating block At the same time, the metal fused deposition module is moved in a plane according to the cross-sectional profile information of the thin-walled structural member. During the plane movement, the molten metal flows out from the nozzle and is deposited on the substrate. The molten metal deposited on the substrate After cooling, a layer of cross-sectional profile of thin-walled structural parts is formed;

3) The substrate is lowered to the height of the cross-sectional profile of one layer, and then the molten metal flowing out of the nozzle is used to deposit the next layer of cross-sectional profile, so that the next layer of cross-sectional profile is formed on the cross-sectional profile of the substrate;

4) Repeat step 3) until a complete thin-walled structural member is obtained.

Before depositing the cross-sectional profile of the first layer, the temperature of the substrate is adjusted to be as close as possible to but lower than the melting point of the deposited metal, and the temperature of the substrate is maintained until a complete thin-walled structural part is obtained.

The flow of molten metal is controlled by the nozzle and the wire feeding speed.

The diameter of the metal wire is in millimeter order to micron order.

During the process of the molten metal flowing out from the nozzle and being deposited on the substrate or cross-sectional profile, the molten metal is gradually solidified from a molten state under the action of an external uniform temperature field.

The beneficial effects of the present invention are reflected in:

The invention adopts threaded pipe, nozzle, heating block and heating pipe to realize melting metal wire and output metal liquid for forming, which not only has reasonable structure, low cost and easy maintenance, but also can solve the problem that the molten state of metal material is difficult to control, making the metal wire The material is smoothly transformed into liquid metal and deposited on the substrate, and a complete thin-walled structural member composed of multi-layer deposition structures is obtained through the lifting and matching of the substrate.

In the invention, the metal wire is sent to the nozzle by the wire feeding mechanism and heated to a molten state. The nozzle moves in the x-y plane according to the cross-sectional profile information of the thin-walled structural part, and at the same time controls the flow rate of the molten metal liquid to make the viscous metal liquid evenly It is deposited on the substrate, and after rapid cooling, the cross-sectional profile of the thin-walled part is formed. After one layer of molding is completed, the substrate is lowered by the height of the cross-sectional layer, and then the next layer is deposited. In this cycle, the product prototype of the metal thin-walled structural part is finally obtained. , due to the use of the principle of fused deposition and the use of metal as the forming material, it has the advantages of high processing flexibility, stable product quality, small heat-affected zone, small thermal deformation of the workpiece, and small follow-up processing. The manufacturing efficiency and performance of thin-walled structural parts are greatly reduced, and the possibility of mass production by fused deposition methods is improved.

Description of drawings

Fig. 1 is the schematic diagram of the present invention utilizing the metal fused deposition method to form a thin-walled structural part;

Figure 2 is an electron microscope structure diagram of the same cladding layer with different magnifications; (a) is magnified 40 times; (b) is magnified 120 times;

In the figure: 1. Base plate; 2. Front heating device; 3. Nozzle; 4. Heating block; 5. Heating pipe; 6. Support; 7. Threaded pipe; 8. Metal wire; 9. Wire feeding mechanism.

detailed description

The present invention will be further described below in conjunction with drawings and embodiments.

Referring to FIG. 1 , the device for forming thin-walled structural parts by metal fused deposition according to the present invention includes a substrate 1 and a metal fused deposition module. The surface of the substrate 1 is flat, and the substrate 1 can be continuously heated. The metal fused deposition module is arranged on Above the substrate 1, the metal fusion deposition module can move horizontally, and the substrate 1 can be lifted; the metal fusion deposition module includes a support 6, a threaded pipe 7 arranged on the support 6, a heating block 4 arranged on the threaded pipe 7 and a In the heating tube 5 in the heating block 4, the outlet end of the threaded tube 7 is provided with a nozzle 3 opposite to the substrate 1, and the inlet end of the threaded tube 7 is provided with a wire feeding mechanism 9; the device for forming a thin-walled structural member also includes A pre-heating device 2 for forming a uniform temperature field between the outlet of the nozzle 3 and the substrate 1 .

The substrate 1 and the metal fused deposition module can be placed in a protective cover filled with protective gas, and the cross-sectional profile of the thin-walled structural member is formed in the environment filled with protective gas.

Based on the above-mentioned device for forming thin-walled structural parts, the present invention provides a method for forming thin-walled structural parts by metal fusion deposition. To the nozzle, a heating tube is installed inside the heating block (specifically, a heating aluminum block). According to the different melting points of the metal wire, different temperatures can be adjusted so that the metal wire is heated to a molten state when it is sent to the nozzle. The nozzle moves in the x-y plane according to the cross-sectional profile information of the thin-walled structural parts, and at the same time squeezes and controls the flow of molten metal, so that the viscous metal liquid is evenly deposited on the preheated substrate, and a thin layer of metal is formed after rapid cooling. For the cross-sectional profile of the wall structure, after one layer is formed, the next layer is deposited, and so on, and finally the product prototype of the metal thin-wall structure is obtained.

The above-mentioned method for forming a thin-walled structural member by metal fused deposition comprises the following steps:

1) Use the heating tube 5 to heat up the heating block 4 to the set temperature; 2) After step 1), use the metal wire 8 as the forming material, and use the wire feeding mechanism to feed the metal wire 8 (generally, the diameter of the metal wire is less than 2mm) from the inlet of the threaded pipe 7 to the nozzle 3, the metal wire 8 is transformed into a molten metal by the temperature of the heating block during the conveying process; at the same time, the metal fused deposition module is The contour information moves in a plane, and the nozzle is one of the components of the metal fusion deposition module. When the metal fusion deposition module moves, the nozzle also moves correspondingly. During the plane movement, the molten metal flows out from the nozzle 3 and deposits on the substrate 1 , the molten metal deposited on the substrate 1 is cooled to form a cross-sectional profile of a thin-walled structural member; 3) The substrate 1 is lowered to the height of the cross-sectional profile, and then the molten metal flowing out of the nozzle 3 is used for the next layer Deposition of the cross-sectional profile, so that the cross-sectional profile of the next layer is formed on the cross-sectional profile on the substrate 1; 4) Step 3) is repeated until a complete thin-walled structural member is obtained.

In this method, before depositing the cross-sectional profile of the first layer, the temperature of the substrate 1 is adjusted to be as close as possible to but lower than the melting point of the deposited metal, so that the cross-sectional profile deposited on the substrate is close to a molten state, and before obtaining a complete thin-walled structural part , maintain the temperature of the substrate 1, and control the flow rate of the molten metal through the nozzle 3 and the wire feeding speed; during the process of the molten metal flowing out from the nozzle 3 to depositing on the substrate or the cross-sectional profile, the molten metal is in a uniform temperature field outside Under the action, it gradually solidifies from the molten state.

The following is a specific introduction: as shown in Figure 1, in the forming process of thin-walled structural parts, the metal wire 8 is used as the forming material, and the metal wire 8 enters the threaded pipe 7 through the wire feed roller until the nozzle 3, and the threaded pipe 7 is formed by The bracket 6 is positioned, the outside of the threaded pipe 7 is the heating block 4 with the heating pipe 5 inside, the threaded pipe 7, the nozzle 2, the bracket 6, the heating pipe 5 and the heating block 4 are fixed together, the nozzle, the heating block, the bracket, the threaded pipe and wire feeding rollers are all set above the substrate, which can realize the overall movement in the x-y direction. The substrate 1 is fixed on the worktable that can move up and down, and the mutual independent control system ensures the relationship between each other (up and down movement of the substrate and x-y direction movement) does not interfere and can coordinate with each other. According to the different melting points of the metal wire, the temperature of the heating block can be adjusted differently through the heating tube, so that the metal wire has been melted to form a molten liquid when it is sent to the nozzle part and is extruded through the nozzle. Under the control of the computer, the nozzle follows a thin-walled structure. The cross-sectional profile information of the workpiece moves in the x-y plane, and the extruded molten liquid (droplet) is deposited on the upper surface of the substrate 1 at a certain speed v, so that the metal molten material is selectively deposited on the substrate 1. After rapid cooling (the metal itself solidifies quickly), a layer of thin-walled structural parts (such as wings) is formed (section layer), and the substrate 1 is fixed on a worktable that can move up and down. After the completion, the substrate is lowered to the height of a cross-sectional layer, and then the next layer is deposited, and this cycle is repeated, and finally the product prototype of the thin-walled structural part is obtained. Using this method greatly improves the formability of thin-walled structural parts.

In order to avoid metal oxidation during the forming process, the entire forming should be carried out in a protective cover filled with protective gases such as argon or nitrogen.

Parameters such as the thickness of each layer of deposition can be controlled by a computer and its parameter settings can be adjusted and optimized according to the requirements of the part.

Preheating the substrate can ensure the fusion of the metal droplet and the substrate, and the temperature of the substrate after preheating is as close as possible to and lower than the melting point of the metal wire. During the forming process, the substrate is kept at the preheated temperature.

The present invention takes solder wire (metal wire) as the research object to conduct a preliminary test. When it is heated above the melting point of the solder wire to form molten droplets, it is dropped on the unheated substrate and the substrate heated to about 5°C below the melting point for comparison. , respectively cut samples for metallographic analysis (perpendicular to the length of the forming track). After being polished by sandpaper, it was corroded with ferric chloride hydrochloric acid aqueous solution, and then its spreading state and internal structure were compared by electron microscopy, as shown in Figure 2. The visual results are obtained through experiments. When the substrate is heated to close to the melting point of the metal wire, the deposition is performed. At this time, the combination of the droplet and the substrate is the best, and they can be well fused together. When the substrate has not been preheated, the droplet deposition is performed. , the molten droplets solidify quickly and cannot be well integrated with the substrate, which easily leads to deformation of the final formed thin-walled structural part.

A pre-heating device is installed near the workpiece at the nozzle outlet, and the pre-heating device provides a uniform temperature field.

In addition, through tests, the present invention also finds that the smaller the size of the droplet, the higher the accuracy of forming the workpiece. At the same time, the greater the roughness of the substrate, the more unfavorable it is for the spreading of the droplet, and it also prevents the fusion of the droplet and the substrate well.

Parameters such as wire diameter, nozzle diameter, deposition rate, and substrate temperature can be adjusted and optimized according to part requirements.

Metal wire is a forming material, and in order to ensure forming accuracy, its diameter is generally less than 2 mm or even to the micron level.

The present invention replaces the laser with a heating block 4 with a heating tube 5 to keep the molten metal material just above the melting point. The movement of the nozzle is controlled by the CAD layered data. When it moves along the x-y direction, the molten metal wire material It is extruded from the nozzle and solidified to form a thin layer of contour shape, each layer thickness ranges from 0.025-0.762mm, layer by layer, and finally forms a model of thin-walled structural parts. Another innovative point of the present invention is to adopt metal wire material. Its biggest advantage is dimensional stability. It is not only easy to form, but also has high forming precision. Time and environmental exposure will not change the size or other characteristics of the formed workpiece. After reaching room temperature, the dimensions are fixed. In addition to the above features, by adding a pre-heating device, the formed thin-walled structural parts have achieved unexpected improvements in performance: on the one hand, the molten liquid slows down the solidification process after it flows out of the nozzle; on the other hand, the formed structure The parts are in a relatively uniform temperature field, and the molten metal is gradually cooled and solidified to complete the deposition, reduce the internal stress of the formed parts, strengthen the fusion between the layers of the parts, and avoid pores inside the final formed thin-walled structural parts, thereby avoiding cracking.

The invention has the following advantages: (1) no expensive laser is used, and the maintenance is simple and the cost is low. (2) The wire material is easy to replace during the forming process. The metal wire is used for direct forming, and the metal wire can be removed after processing. No material waste will be caused. (3) The molding speed is fast. Through experiments, the highest molding speed of models with certain structural characteristics can reach 60cm ³ /h. Through software optimization and technological progress, it is expected to reach a high speed of 200cm ³ /h.

The present invention is not only a new method for thin-walled structural parts manufacture, but also an innovation in materials of fused deposition method (FDM). Processing with this method has high flexibility, stable product quality, small heat-affected zone, small thermal deformation of the workpiece, and small follow-up processing, which effectively improves the performance of thin-walled structural parts and greatly reduces manufacturing costs.

Claims (10)

1. A device for forming thin-walled structural parts by metal fused deposition, characterized in that: the device for forming thin-walled structural parts includes a substrate (1) and a metal fused deposition module, and the metal fused deposition module includes a bracket (6) , the threaded pipe (7) arranged on the bracket (6), the heating block (4) arranged on the threaded pipe (7) and the heating pipe (5) arranged in the heating block (4), the threaded pipe (7) The outlet end of the pipe is provided with a nozzle (3) opposite to the base plate (1), and the inlet end of the threaded pipe (7) is provided with a wire feeding mechanism (9). 2 . The device for forming thin-walled structural parts by metal fused deposition according to claim 1 , characterized in that: the surface of the substrate ( 1 ) is flat, and the substrate ( 1 ) can be continuously heated. 3 . 3. A device for forming thin-walled structural parts by metal fused deposition according to claim 1, characterized in that: the metal fused deposition module is arranged above the base plate (1), the metal fused deposition module can move horizontally, and the base plate (1) It can be raised and lowered. 4. A device for forming thin-walled structural parts by metal fused deposition according to claim 1, characterized in that: the substrate (1) and the metal fused deposition module are arranged in a protective cover filled with protective gas, and the thin-walled The cross-sectional profile of the structural part is formed in an environment filled with protective gas. 5. A device for forming thin-walled structural parts by metal fused deposition according to claim 1, characterized in that: the device for forming thin-walled structural parts also includes a device for connecting the outlet of the nozzle (3) with the substrate ( 1) The front heating device (2) that forms a uniform temperature field between them. 6. A method for forming a thin-walled structural member using a device for forming a thin-walled structural member by metal fused deposition as claimed in claim 1, characterized in that: comprising the following steps: 1) Use the heating tube (5) to heat up the heating block (4) to the set temperature; 2) After step 1), the metal wire (8) is used as the forming material, and the wire feeding mechanism (9) is used to transport the metal wire (8) from the inlet of the threaded pipe (7) to the nozzle (3), and the wire The material (8) is transformed into molten metal by the temperature of the heating block during the conveying process; at the same time, the metal fused deposition module is moved in a plane according to the cross-sectional profile information of the thin-walled structural member, and the molten state is made to move during the plane motion. The metal flows out from the nozzle (3) and is deposited on the substrate (1), and the molten metal deposited on the substrate (1) is cooled to form a layer of cross-sectional profile of the thin-walled structural member; 3) The substrate (1) is lowered to the height of the cross-sectional profile of one layer, and then the molten metal flowing out of the nozzle (3) is used to deposit the next layer of cross-sectional profile, so that the next layer of cross-sectional profile is formed on the substrate (1) on the cross-sectional profile; 4) Repeat step 3) until a complete thin-walled structural member is obtained. 7. The method for forming a thin-walled structural part by using the device for forming a thin-walled structural part by metal fused deposition according to claim 6, characterized in that: before depositing the cross-sectional profile of the first layer, the temperature of the substrate (1) is adjusted to as much as possible The temperature of the substrate (1) is maintained close to but lower than the melting point of the deposited metal until a complete thin-walled structure is obtained. 8. The method for forming a thin-walled structural part by using the device for forming a thin-walled structural part by metal fusion deposition according to claim 6, characterized in that: the flow rate of the molten metal is controlled by the nozzle (3) and the wire feeding speed. 9 . The method for forming a thin-walled structural member using a metal fused deposition forming device according to claim 6 , characterized in that: the diameter of the metal wire ( 8 ) is on the order of millimeters to microns. 10. The method for forming a thin-walled structural part by using the device for forming a thin-walled structural part by metal fusion deposition according to claim 6, characterized in that: the molten metal flows out from the nozzle (3) and is deposited on the substrate or the cross-sectional profile During the process, the molten metal is gradually solidified from the molten state under the action of the external uniform temperature field.