CN106623928A - Device for entering and exiting of shielding gas on two sides of forming bin of metal 3D printing equipment - Google Patents

Abstract

The invention provides a device for the entry and exit of protective gas on both sides of a forming chamber of a metal 3D printing equipment. Generally, the air outlet and air inlet equipment of the internal working chamber of the metal selection forming equipment are simple channel devices or rectangular devices. The common problem is that the airflow generated by the air inlet during the laser sintering powder process is difficult to blow away the black smoke and metal vapor plasma generated by the interaction between the laser and the powder, which causes a large loss of laser power and causes melting The irregular shape of the pool seriously affects the molding quality and molding accuracy of the molded parts. Or blow the black smoke of powder sintering near the air inlet to the powder layer near the air outlet to affect the printing work. The present invention is mainly to design a specific device so that the airflow forms a stable laminar flow and effectively blows away the black smoke and metal vapor plasma generated during laser sintering powder, which can increase the utilization rate of laser energy by about 10%-15%, and effectively improve The quality and precision of the molded parts make the density of the molded parts close to 100%.

Description

A device for the entry and exit of protective gas on both sides of the forming chamber of metal 3D printing equipment

technical field

The invention relates to a device for protecting gas in and out of the forming chamber of metal 3D printing equipment, which mainly solves the problem of serious loss of laser caused by black smoke and metal plasma generated during laser sintering powder in the process of selective laser melting and forming, so that it can Improve the utilization rate of laser energy by about 10%-15%, and effectively improve the quality and precision of molded parts, making the density of molded parts close to 100%.

Background technique

Today's market environment is undergoing tremendous changes. On the one hand, consumers' needs are increasingly personalized and diversified; on the other hand, product manufacturers are all focusing on the fierce competition in the global market. Faced with such a rapidly changing and unpredictable buyer's market, manufacturers must not only quickly design products that meet people's consumption needs, but also produce them quickly in order to seize the market. The traditional mass production mode responds slowly to the market and cannot quickly respond to market demand. For this reason, industrialized countries have been working hard to develop new manufacturing technologies and improve the level of manufacturing development in the past ten years, so as to occupy a place in the fierce global competition. Thanks to the development and progress of computer, microelectronics, information, automation, new materials and modern enterprise management technology, major changes have taken place in product design, processing and manufacturing, quality inspection, production management and enterprise management, resulting in a batch of new Manufacturing technology and manufacturing mode, manufacturing engineering and science have achieved unprecedented development.

Rapid prototyping technology is gradually formed and developed under this background. The development of rapid prototyping technology has greatly shortened the product design and manufacturing cycle, improved the first-time success rate of product design and manufacturing, and reduced product development costs, thus bringing fundamental changes to the manufacturing industry. Rapid prototyping (RP) is a new type of product manufacturing that integrates computer-aided design and manufacturing technology, reverse engineering technology, layered manufacturing technology (SFF), material removal forming (MPR), and material adding forming (MAP) technologies. technology. In layman's terms, rapid prototyping technology is to use three-dimensional CAD data to accumulate layers of materials into solid prototypes through rapid prototyping machines. In the case of increasingly fierce market competition, product innovation and speed to market, as well as the flexibility of manufacturing technology must become the core competitiveness of enterprises. Together, rapid prototyping technology and virtual reality technology are important means and powerful tools for product digital development. At the same time, they have also become an integral part of the advanced manufacturing technology group and have been more and more widely used in the manufacturing industry. Compared with the traditional manufacturing process, after adopting laser rapid prototyping and laser rapid molding technology, the mold preparation work of product trial production and mass production can be operated in parallel, which can significantly shorten the cycle of new product design and trial production, and save product development costs.

Among them, the most widely used laser rapid prototyping technology is selective laser melting (as shown in Figure 1). Selective laser melting (SLM-Selective Laser Melting) is a direct forming method for metal parts and is the latest development of rapid prototyping technology. This technology is based on the most basic idea of rapid prototyping. It uses layer-by-layer addition to directly form parts with specific geometric shapes according to CAD data. During the forming process, the metal powder is completely melted to produce metallurgical bonding. This technology breaks through the traditional processing method to remove the concept of forming, and adopts the method of adding materials to form parts, which minimizes the waste of materials; the forming process is almost not limited by the complexity of the parts, so it has great flexibility, especially suitable for Manufacture of small batches of one-piece products.

At present, various companies, research institutions, universities and other institutions at home and abroad have developed various molding equipment for selective laser melting technology. Although the molding equipment has differences in structure and shape, its working principle is very similar (as shown in Figure 2). There are still some problems that are common in these already produced devices. Problem 1: During the molding process, because the laser sintering powder layer will generate a large amount of black smoke and metal vapor plasma, the laser power will be greatly attenuated, resulting in poor quality and poor dimensional accuracy of the molded parts. Some even directly affect the quality of single-layer powder melting, making it difficult to continue the printing process.

Question 2: Even if the protective gas is enough to blow away the black smoke and metal vapor plasma during the molding process without affecting the power of the laser, but because some equipment has a relatively large printing format, in order to avoid excessive stress on the entire surface during laser scanning, you will generally choose Diagonal scanning or checkerboard scanning, at this time, the black smoke and large particles near the air outlet will be blown and scattered on the surface of the workpiece near the air suction port, thus affecting the powder spreading and sintering quality of the next layer.

Faced with this problem, the present invention designs a device installed at the gas outlet and suction port of the working compartment of the selective melting molding equipment, which can make the protective gas form a stable and strong laminar flow, thereby greatly improving the single-layer sintering performance and improving the molded parts. precision and quality.

Contents of the invention

In order to overcome the defects described in the background technology, the present invention designs a set of protective gas inlet and outlet devices installed on both sides of the molding bottom plate from the printing mechanism and molding process of the related metal printer. The purpose of this device is to prevent the black smoke and metal vapor plasma (as shown in Figure 3) generated by the interaction between the laser and the powder from being blown away by the airflow generated by the air inlet during the laser sintering powder process during the printing process, so as to prevent The power loss of the laser is large, which causes the irregular shape of the molten pool, which seriously affects the molding quality and molding accuracy of the molded parts. Or blow the black smoke of powder sintering near the air inlet to the powder layer near the air outlet to affect the printing work. The specific device of the present invention is to make the air flow form a stable laminar flow (as shown in Figure 4) and effectively blow away the black smoke and metal vapor plasma generated during the laser sintering powder, thereby increasing the laser energy by about 10%-15%. Utilization rate, and effectively improve the quality and precision of molded parts, so that the density of molded parts is close to 100%.

1. A device for the ingress and egress of protective gas in the internal working chamber of metal 3D printing equipment, which is characterized in that: the device is composed of two parts, namely an air inlet device and an air outlet device; the two devices are parallel and opposite in the forming chamber Placed on both sides of the forming base;

The air flow of the air intake device is divided into upper and lower layers, and the flow channels of the upper and lower layers are separated by a partition; the end of the lower flow channel near the air inlet is 50mm long, and it is horizontally forward; Angle to the exit, the upper flow channel has no inclination, and is horizontal to the exit;

The upper and lower flow channels are vertically separated by multiple plates to form a cuboid channel. The end of the vertical partition is 5-10mm away from the gas outlet so that the gas can be mixed evenly before going out from the gas outlet.

The air outlet device is composed of five parallel flow channels up and down, and the air outlet of the air outlet device is designed to be curved.

2. Further, the plates are made of thin stainless steel plates with a thickness of 1 mm. The height of the air inlet device is 30mm, the height of the air outlet device is 50mm, and the width of the air inlet device and the air outlet device is equal to the width of the substrate in the corresponding printing equipment.

3. Further, the airflow of the air intake device is divided into upper and lower layers with heights of 20mm and 10mm respectively.

4. Furthermore, the air outlet of the air intake device is composed of multiple small holes, the diameter of the air outlet hole of the upper flow channel is 4mm, and the diameter of the air outlet hole of the lower flow channel is 3mm.

5. Further, the end of the vertical partition of the air inlet device is 10mm away from the air outlet.

6. Further, the five channels of the air outlet device are separated by partitions and distributed evenly in the height direction; the arc-shaped bending area and the horizontal and vertical areas are all connected tangentially, and the central angles are all 90 degrees.

7. Further, there are screw holes on both sides of the air intake device to be fixed in the working compartment; the left side of the air outlet device is designed to facilitate the connection with the air extraction motor equipment outside the equipment, and the shape and size of the interface are the same as those of the corresponding equipment. The suction device has the same shape.

8. Further, the air inlet and outlet devices are placed in parallel on both sides of the molding base material, the horizontal distance and vertical distance from the lower left corner of the air inlet device to the molding base material are both 10 mm, and the lower right corner of the air outlet device is 10 mm from the molding base material. The horizontal distance of the material is 10mm and the vertical distance is 5mm.

The specific features of the device of the present invention are as follows.

1. A device for the protection gas in and out of the internal working compartment of metal 3D printing equipment consists of two parts, namely the air intake device and the air outlet device. The two devices are parallel and opposed to each other and placed on both sides of the forming bottom plate in the forming chamber. The lower left corner of the air inlet device is 10mm horizontally and vertically away from the forming substrate, and the lower right corner of the air outlet device is 10mm horizontally and 5mm vertically away from the forming substrate. (as shown in Figure 7). The height of the air inlet device is designed to be 30mm, and the height of the air outlet device is set to 50mm. The width of both devices is equal to the width of the forming substrate of the actual metal printing equipment used. During the actual printing process, the shielding gas will blow the black smoke and black particles to the direction of the suction port. Due to the effect of gravity, some black particles may fall on the scanning area and cause unnecessary impact. Therefore, the outlet device is slightly higher than the inlet device when installed, so that the laminar flow has an oblique upward angle to reduce the probability of black particles falling on the scanning area.

2. The material of the air inlet device and the air outlet device are all stainless steel sheets with a thickness of 1mm. The airflow of the air intake device is divided into upper and lower layers with heights of 20mm and 30mm respectively, and the flow channels of the upper and lower layers are separated by a partition. The end of the lower channel near the air inlet is 50mm long, and it is horizontally forward; the end near the air outlet is 100mm long, and it is inclined upward at a 5-degree angle to the outlet. The upper channel has no inclination and is horizontal to the outlet. The purpose of dividing the air intake layer into two layers is to obtain a laminar flow that is more suitable for blowing away black smoke. The 5-degree inclination of the lower flow channel will make the air flow carry the black impurities to flow upwards, that is, give the black impurities an initial velocity upwards, and then the horizontal laminar flow of the upper flow channel will carry the black impurities directly to the position of the air outlet. Flow, the cooperation of the upper and lower flow channels can avoid the disadvantages of falling to the other end of the slice data due to the gravity of the black particles when printing large-format slice data, and play a better protective role.

3. The upper and lower flow passages of the air intake device are vertically separated by multiple thin plates, so that each layer of air flows vertically separately. In addition, the air outlet of the air intake device is composed of many small holes. The purpose of the small holes is to prevent the airflow from the flow channel from being transported over a long distance, and the flow velocity of each part is different, resulting in turbulent flow near the air inlet, which cannot blow effectively. Go smoky. Among them, the diameter of the air outlet hole of the upper flow channel is 4mm, and the air outlet of the lower flow channel is narrower, with a hole diameter of 3mm.

4. The air outlet device is composed of 5 flow channels, and the multiple flow channels are also to prevent the air flow from being disturbed. The air outlet is designed to be curved and the radius of the curved arc is 35mm. The purpose is to provide a better transition when the airflow turns and is more beneficial to the flow of the airflow.

5. There are two screw holes on both sides of the air intake device. During specific installation, two screw holes can be reserved in the corresponding position inside the working chamber to cooperate with the air intake device. The left side of the air outlet device finally converges at a square converging port , can be directly connected to the suction filter device of the equipment.

6. The air inlet and outlet devices are arranged in parallel on both sides of the forming substrate. Because the horizontal and vertical distance between the air inlet device and the substrate is too far, it will be difficult to completely blow away impurities such as black smoke, and if the distance is too close, it will It is very easy to blow off the powder layer on the substrate, so according to the process experience, the horizontal distance and vertical distance from the lower left corner of the air inlet device to the forming substrate are both 10mm; while the horizontal and vertical distance from the position of the air outlet device to the substrate is too If it is far away, the black impurities brought by the air intake device cannot be sucked in time and effectively, and if it is too close, it is easy to suck away the powder on the substrate, and because the air intake device has an angle of 5 degrees upward, the right side of the air outlet device is designed according to process experience. The horizontal distance from the lower corner to the molding base material is 10mm and the vertical distance is 5mm.

Description of drawings

Fig. 1 Schematic diagram of selective laser melting equipment (including: 1, PC terminal 2, fiber laser 3, beam isolator 4, beam expander 5, vibrating mirror 6, F-θ mirror 7, air outlet 8, scraper 9, recycling Filtration system 10, recovery cylinder 11, molding cylinder 12, powder supply cylinder)

Figure 2 Partial structural diagram of the forming chamber of the selective laser melting equipment (including: 13, scraper 14, forming bottom plate 15, air inlet 16, and air outlet)

Figure 3 Schematic diagram of selective laser melting process (including: 17, black smoke and metal vapor plasma 18, laser beam 19, metal particles)

Figure 4 Schematic diagram of air flow between the inlet and outlet

Figure 5. A side view of the air intake device (including: 20, reserved screw holes)

Figure 5. Top view of B air intake device

Figure 5. Schematic diagram of the inclination angle of the lower airway of the C air intake device

Figure 5. The physical picture display of the D air intake device

Figure 6. A isometric side view of the air outlet device

Figure 6. Front view of B outlet device

Figure 6. Top view of C outlet device

Figure 6. The physical picture of the D gas outlet device

Figure 7 is a schematic diagram of the placement of the air inlet and outlet devices and a schematic diagram of the inclined air flow (including: 21, the forming substrate 22, the air outlet device 23, and the air inlet device)

Figure 8. A schematic diagram of the engine impeller and printing substrate

Figure 8. Schematic diagram of the bottom surface of the impeller of the B engine

detailed description

The present invention will be summarized in further detail below in conjunction with specific embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

Specific examples:

This embodiment is the application of the air inlet and outlet device in the selective laser melting equipment in the manufacturing process of the aluminum alloy engine impeller (Fig. 8.A). It is well known that aluminum alloy powder is lighter than other metal powders, and its fluidity is poor, the effect of powder spreading is not good, and it is easy to generate dust. Therefore, during the process of selective laser melting, black smoke and sparks are easily generated above the molten pool. And as shown in Figure 8.B, some engine impellers are larger in size, so the slices at the bottom are larger.

When choosing a general horizontal air inlet and outlet device, it is difficult to blow away a large number of black particles and smoke in time because the air flow does not form a strong and stable laminar flow. At this time, the laser power will be greatly attenuated, resulting in the bottom powder cannot be melted penetration, and irregular molten pool morphology. This not only affects the scanning and melting of the lower layer of powder, but also easily warps the sintered body due to stress, blocks the scraper from scraping the powder, and eventually leads to the termination of the printing process. Even if some devices can blow away the black smoke and particles in time without affecting the power of the laser, the cut surface of the impeller shown in Figure 8.B is too large, and the airflow on the intake side will blow the burned black particles Take away from the laser powder interaction area, but the black particles will still fall to the other side of the slice data due to gravity, which will affect the powder laying accuracy of the lower layer and the sintering of the laser, and affect the internal performance of the molded part. In severe cases, the printing The process stops. When the air inlet and outlet device in the present invention is selected, the laminar flow formed by the two layers of stable airflow at the air inlet can easily take away impurities such as black smoke generated by the interaction of laser powders, and the lower airflow has an inclination angle of 5 degrees obliquely upward. Make the lower layer laminar flow have an oblique upward initial velocity, that is, give the black impurities an oblique upward initial velocity, and when they encounter the upper layer parallel laminar flow, they are taken away horizontally. When installing, the air outlet is slightly higher than the air inlet, and the suction of the air outlet will suck the black impurities brought by the air inlet obliquely upward. The practicality of this device can not only improve the forming accuracy of the printed parts, but also enable some difficult-to-machine workpieces to be successfully processed.

The air inlet and outlet device of the present invention has been designed for better assembly with the printer. For example, two screw holes are respectively arranged at both ends of the air inlet device, and a quadrilateral interface is left on one side of the air outlet device to directly connect with the printer. The suction connection of the device. This kind of device is developed by combining metal printing equipment and technology and actual printing experience, which can make metal printing work easier, improve the performance of printed workpieces, and expand the shape range of metal printed parts. In addition, the manufacturing material of this device is cheap and easy to obtain, and the manufacturing method can be directly processed by a stainless steel sheet machine, which has the advantages of simple manufacturing, low processing cost, strong practicability, etc., is suitable for mass production, and has great economic benefits.

Claims (8)

1. A device for the ingress and egress of protective gas in the internal working chamber of metal 3D printing equipment, which is characterized in that: the device is composed of two parts, namely an air inlet device and an air outlet device; the two devices are parallel and opposite in the forming chamber Placed on both sides of the forming base; The air flow of the air intake device is divided into upper and lower layers, and the flow channels of the upper and lower layers are separated by a partition; the end of the lower flow channel near the air inlet is 50mm long, and it is horizontally forward; Angle to the exit, the upper flow channel has no inclination, and is horizontal to the exit; The upper and lower flow channels are vertically separated by multiple plates to form a cuboid channel, and the end of the vertical partition is 5-10mm away from the gas outlet so that the gas can be mixed evenly before going out from the gas outlet; The air outlet device is composed of five parallel flow channels up and down, and the air outlet of the air outlet device is designed to be curved. 2. The device according to claim 1, characterized in that: said plates are made of thin stainless steel plates with a thickness of 1 mm. The height of the air inlet device is 30mm, the height of the air outlet device is 50mm, and the width of the air inlet device and the air outlet device is equal to the width of the substrate in the corresponding printing equipment. 3. The device according to claim 1, characterized in that: the airflow of the air intake device is divided into upper and lower layers with heights of 20mm and 10mm respectively. 4. The device according to claim 1, characterized in that: the air outlet of the air inlet device is composed of a plurality of small holes, wherein the diameter of the air outlet hole of the upper flow channel is 4mm, and the diameter of the air outlet hole of the lower flow channel is 3mm. 5. The device according to claim 1, wherein the end of the vertical partition of the air inlet device is 10mm away from the air outlet. 6. The device according to claim 1, wherein the 5 flow channels of the air outlet device are separated by partitions and are evenly distributed in the height direction; the arc-shaped bending area is connected tangentially to the horizontal and vertical areas, and the central angle is 90 degrees. 7. The device according to claim 1, screw holes are left on both sides of the air inlet device to be fixed in the working chamber; the left side of the air outlet device is designed to be conveniently connected with the air extraction motor equipment outside the equipment, and the interface is reserved. The shape and size correspond to the shape of the suction device of the corresponding equipment. 8. The device according to claim 1, the placement position of its air inlet and outlet devices is to be arranged in parallel on both sides of the molding substrate, the lower left corner of the air inlet device is 10mm from the horizontal distance and the vertical distance of the molding substrate, and the air outlet The horizontal distance from the lower right corner of the device to the molding substrate is 10mm and the vertical distance is 5mm.