CN1295051C - Rapid forming system for direct manufacturing metal parts - Google Patents

Abstract

The present invention discloses a rapid forming system which directly manufactures metal parts. A gas inlet and a gas outlet are arranged in both sides of a gas protection cavity; the upper surfaces of both ends of the system are provided with a left and a right powder dropping devices for containing metal powder. The powder dropping devices are controlled by a motor to discharge powder; a powder outlet of the system is communicated with the left and the right powder dropping devices. A scraper is positioned in the gas protection cavity and is controlled by the motor to move bidirectionally in the horizontal direction. A laser scanning device is positioned between the left and the right powder dropping devices. The top of the gas protection cavity is provided with a laser window; the bottom of the gas protection cavity is provided with a working cavity. A piston which moves up and down and is controlled by the motor is arranged in the working cavity. Light beams emitted by the laser scanning device are focalized on powder which needs to be processed on the upper surface of the piston through the laser window. The present invention can directly produce metal parts with good mechanical properties, such as high density, high strength, high precision, etc., and any complicated shape. The present invention has the characteristics of high manufacturing speed and low manufacturing cost.

Description

A rapid prototyping system for direct manufacturing of metal parts

technical field

The invention belongs to the field of rapid manufacturing, in particular to a rapid prototyping system for directly manufacturing metal parts.

Background technique

Practice has proved that using rapid prototyping technology to make polymer parts is effective, but there are many technical difficulties in making metal parts. Although some rapid prototyping methods can directly manufacture metal parts, more are obtained through indirect methods. For example: Selective Laser Sintering (Selective Laser Sintering, SLS) method - by selecting high-melting point metal powder materials and low-melting point powder materials to manufacture metal parts, that is, mixing two metal powders with different melting points or adding some kind of metal powder to the metal powder Binder, using a small laser power (generally below 100W) to melt part of the low melting point metal powder or binder, the molten powder material is bonded to the surrounding unmelted metal powder to form a rough body, and then the green body is subjected to high temperature Roasting, metal infiltration and other post-processing to form metal parts. Using the existing methods to quickly manufacture complex metal parts has a series of problems such as low density, poor mechanical properties, high production cost, complicated manufacturing process and long production cycle. In order to solve these problems, a selective laser melting (Selective Laser Melting, SLM) method that can directly manufacture high-density metal parts has been developed.

The Fraunhofer Institute in Germany developed SLM technology in 2002. At present, the German MCP company and F&S company are already producing and selling SLM machines. The equipment they manufactured can directly manufacture metal parts without subsequent treatment such as metal penetration. Moreover, a workpiece with 100% compactness can be obtained. However, the galvanometer laser scanning system is adopted in the equipment they manufactured, which can only produce metal parts of 5cm ² per hour, and the production efficiency is low; moreover, the machines they manufacture are larger in size and higher in price.

In China, there have been patent applications for the rapid prototyping method, system and powder feeding device for direct manufacturing of metal parts, which are respectively "method and system for rapid thin-wall forming of powder materials by laser vaporization sintering" (publication number CN1363440A, open date August 14, 2002) and "Laser three-dimensional rapid micro-molding nano-phase powder feeding device" (publication number is CN2553946Y, and the public date is June 4, 2003). The SLVS method is used to manufacture metal parts-that is, the heat source of the laser is used to irradiate the low melting point and low boiling point metal alloy powder material (the particle size is generally less than 50 microns). After the laser is focused, the energy is highly concentrated, and the output energy of the laser beam is controlled. , the focus position and the moving speed of the beam and the material, etc., can make the powder material in the center of the spot vaporize and evaporate instantly, while the power density at the edge of the spot is small, and the part in contact with the powder cannot reach the energy required for vaporization. Can be melted, then cooled and solidified into metal parts. It can be seen from the above that only thin-walled metal parts can be manufactured with this equipment, and the metal powder is limited to low melting point and low boiling point metal powder. In addition, the above-mentioned powder feeding device has disadvantages such as complex structure, high manufacturing cost, and mainly transporting nano-phase powder materials.

Contents of the invention

The object of the present invention is to overcome the above disadvantages and provide a rapid prototyping system for directly manufacturing metal parts. The invention can directly manufacture metal parts with any complex shape and good mechanical properties such as high density, high strength and high precision. In addition, by adopting the rapid prototyping system of the present invention, the production speed of metal parts can be accelerated and the production cost can be reduced.

A rapid prototyping system for directly manufacturing metal parts provided by the present invention includes a processing space and a laser scanning device, and is characterized in that: gas inlets and outlets are arranged on both sides of the gas protection chamber, and there are holes on both ends for containing metal powder. The left and right powder falling devices, the powder falling device is controlled by the motor, and its powder outlet is connected to the gas protection chamber; the scraper is located in the gas protection chamber, and is controlled by the motor to move in two directions along the horizontal direction; the laser scanning device is located in the Between the left and right powder falling devices, there is a laser window on the top of the gas protection chamber, a working chamber at the bottom of the gas protection chamber, and a piston controlled by a motor to move up and down in the working chamber, and a laser scanning device. The emitted light beam is focused on the metal powder to be processed on the upper surface of the piston through the laser window.

The invention can directly manufacture metal parts with good mechanical properties such as high density, high strength and high precision in any complex shape. In addition, by adopting the rapid prototyping system of the present invention, the production speed of metal parts can be accelerated, the production cost can be reduced, and funds can be saved. This system is suitable for direct manufacturing of high-density metal parts.

Description of drawings

Fig. 1 is a structural schematic diagram of the SLM rapid prototyping system of the present invention.

Fig. 2 is a structural schematic diagram of a specific embodiment of the powder falling device in Fig. 1 .

FIG. 3 is a schematic structural diagram of a specific embodiment of the laser scanning device in FIG. 1 .

Figure 4 is a control flow chart of the SLM rapid prototyping system.

Detailed ways

Below in conjunction with accompanying drawing and example the present invention is described in further detail.

As shown in Figure 1, in the SLM rapid prototyping system of the present invention, the processing space 9 is composed of left and right powder falling devices 10, 11, laser window 13, scraper 15, piston 18, gas protection chamber 19, working chamber 20 and laser The scanning device 21 is composed. Metal powder is housed inside the left and right powder falling devices 10 and 11, and its powder outlet communicates with the gas protection chamber 19. As shown in Figure 2, the left and right powder falling devices 10 or 11 are provided with impellers 22 with blades 23, and the rotation of the impellers is controlled by a stepping motor. When the two blades turn to the outlet position, the powder automatically falls into the gas protection chamber 19 in. The scraper 15 is located inside the gas protection chamber 19, and the ordinary motor controlled by the frequency converter controls the scraper 15 to move bidirectionally along the horizontal direction for powder spreading. From the left powder falling device 10 to the right powder falling device 11 or from the right powder falling device 11 to the left powder falling device 10, one layer of powder is spread every time; the laser scanning device 21 is located between the left and right powder falling devices 10 and 11. A laser window 13 is arranged on the top of the gas protection chamber 19 . A working chamber 20 is provided at the bottom of the gas protection chamber 19, and a piston 18 is arranged in the working chamber 20, and the piston 18 moves up and down in the vertical direction controlled by a separate stepping motor. The laser beam emitted by the laser scanning device 21 acts on the powder to be processed on the upper surface of the piston 18 through the laser window 13 , and the protective gas enters from the air inlet 12 and is discharged from the gas outlet 14 during the working process. Every time one layer is processed, the piston 18 descends by the thickness of one layer. In the figure, 16 represents the processed part of the workpiece; 17 represents redundant metal powder.

As shown in FIG. 3 , the laser scanning device 21 is composed of an X-axis guide rail 1 , a Y-axis guide rail 2 , polarizers 4 and 7 , a slider 5 , and a focusing mirror 6 . The X-axis guide rail 1 and the Y-axis guide rail 2 are composed of screw rods. The Y-axis guide rail 2 can move in both directions along the horizontal direction under the control of the servo motor. The X-axis guide rail 1 can move along the vertical Y axis on the horizontal plane under the control of another servo motor. The shaft guide rail 2 moves in both directions. The slider 5 can move bidirectionally on the Y-axis guide rail 2 through a screw rod, the focusing mirror 6 and the lower polarizer 4 are fixed on the slider 5 , and the upper polarizer 7 is fixed on the upper end of the Y-axis guide rail 2 . The light beam 8 emitted by the laser changes its running direction through the upper polarizer 7 and the lower polarizer 4 , and after being focused by the focusing mirror 6 , it is focused on the metal powder to be processed on the upper surface of the piston 18 through the laser window 13 .

The control flow chart of the above-mentioned rapid prototyping system is shown in Figure 4. First, the metal powder is preheated to a certain temperature through the preheating device; secondly, a layer of metal powder with a predetermined thickness is spread on the processing platform through the computer-controlled powder falling mechanism; finally, the metal parts are designed with 3D modeling software such as Pro/Engineer and Unigraphic After being processed by slicing software, it is saved as an STL file, and the data information of the STL file is sent to the SLM rapid prototyping system machine. Under the laser scanning system of the X-Y axis scanning mode of the drawing ceremony, the laser is controlled by the computer according to the design. The scanning trajectory runs, the metal powder is melted, and it is manufactured layer by layer. Because when the X-Y axis scanning system of drawing ceremony is adopted, the distance from the processing platform after laser focusing is stable at a specific value, so the spot size will not change, the laser energy density is stable, and it is easy to ensure the processing accuracy; in addition, the two-dimensional vibration In the mirror laser scanning system, the focused spot becomes bigger and bigger as it moves farther away, resulting in a gradual decrease in laser energy density. If no compensation measures are taken, it may lead to lower precision of metal parts and a decrease in processing speed. slow. Therefore, in order to increase the processing speed and obtain higher precision of metal parts, in this rapid prototyping system, we adopt the laser scanning system of X-Y axis scanning method of drawing ceremony. At the same time, we have adopted a powder spreading device combined with an upper and lower powder mechanism and a scraper, and the processing space is located in it, which makes the processing space more compact, reduces the amount of protective gas, and saves costs.

Claims (3)

1, a kind of rapid forming system of direct manufacturing metal parts, comprise processing space and laser scanning device, it is characterized in that: the both sides of gas shield chamber (19) are provided with inlet, outlet (12,14), it is provided with the left and right powder discharging device (10,11) that is used to install metal dust above two ends, powder discharging device is by its powder delivery of Electric Machine Control, and its meal outlet communicates with gas shield chamber (19); Scraper plate (15) is positioned at gas shield chamber (19), makes bidirectional-movement by the Electric Machine Control along continuous straight runs; Laser scanning device (21) is positioned between the left and right powder discharging device (10,11); be provided with laser window (13) at the top of gas shield chamber (19); be provided with working chamber (20) in the bottom of gas shield chamber (19); be provided with the piston (18) by its vertical motion of Electric Machine Control in the working chamber (20), the light beam that laser scanning device (21) sends focuses on the powder to be processed of piston (18) upper surface by laser window (13).

2, system according to claim 1, it is characterized in that: the structure of described laser scanning device (21) is: X-axis guide rail (1) and Y-axis guide rail (2) are made of screw mandrel, but the former is by servomotor control along continuous straight runs motion down, down in horizontal plane upper edge movement in vertical direction, slide block (5) is positioned at Y-axis guide rail (2) and upward and along the Y-axis guide rail slides the latter by another servomotor control; Focus lamp (6) and following polariscope (4) are fixed on the slide block (5), last polariscope (7) is fixed on the upper end of Y-axis guide rail (2), after the light beam (8) that is sent by laser instrument passes through last polariscope (7) and following polariscope (4) successively and changes traffic direction, pass through focus lamp (6) again and focus on, be radiated on the metal dust to be processed that is positioned at piston (18) upper surface by working window (13) again.

3, system according to claim 1 and 2 is characterized in that: for the impeller (22) of band blade (23), by the rotation of Electric Machine Control impeller, make powder fall into gas shield chamber (19) in the described left and right powder discharging device (10,11).

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