Upper powder feeding mechanism of metal 3D printer and metal 3D printer

Abstract

The upper powder feeding mechanism of the metal 3D printer comprises a powder storage bin, a partition plate is arranged in the powder storage bin and divides the inner space of the powder storage bin into an upper powder chamber and a lower powder chamber, a powder adding opening and a cover plate are arranged at the top of the powder storage bin, and a powder supplementing opening is formed between the upper powder chamber and the lower powder chamber; the powder storage bin is provided with a powder supplementing switch assembly capable of opening and closing the powder supplementing opening, a base is arranged at the position of a lower end opening of the powder storage bin, the base is provided with a powder outlet and a drawing type powder falling switch assembly capable of opening and closing the powder outlet, and the outer side wall of the powder storage bin is connected with an air pressure balance pipe communicated with the upper portion of the powder discharging chamber. The air pressure balance pipe is provided with an air valve capable of controlling on-off of the air pressure balance pipe. When the powder feeding mechanism is applied to the metal 3D printer, continuous and precise powder supply can be achieved, shutdown is not needed in the process of adding powder into the powder feeding chamber in the midway, and the work efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal 3D printers, and in particular to an upper powder feeding mechanism of a metal 3D printer and the metal 3D printer. Background Art

[0002] Currently, Slm process metal 3D printers generally use two powder supply methods.

[0003] The first is double-cylinder powder feeding from below, that is, the laser sintering working surface and the powder supply cylinder are placed side by side at the bottom. When working, the laser completes a layer of sintering, and the working surface moves down by a sintering layer thickness under the drive of the cylinder body. The synchronous powder supply cylinder is moved up a certain distance under the drive of the cylinder body, and the powder is pushed out above the working surface. The powder scraper then moves horizontally to level the powder supply cylinder and the working surface, so that the powder forms a dense layer thickness on the working surface again, and the laser starts sintering. Reciprocating, that is, forming a closed-loop sintering work of the Slm process metal 3D printer with double-cylinder powder feeding from below. The disadvantages of the double-cylinder powder feeding technology are: 1. The double cylinders (working surface cylinder body, powder supply cylinder body) are placed side by side at the bottom, which doubles the size of the equipment's working cabin, thereby causing the overall size of the equipment and all cooperating working parts (such as the scraper module) to become larger, and the equipment manufacturing cost (including cabin manufacturing cost and whole machine manufacturing cost) increases. 2. The size of the working chamber doubles, and the demand for protective gas doubles; this results in slower inflation and greater sealing risks; 3. The powder supply cylinder is built-in, and the amount of powder stored is fixed. Refilling powder midway requires downtime, which takes up equipment working time and reduces processing efficiency.

[0004] The second method is to feed powder on a roller, that is, there are only the sintering working surface and the cylinder body in the working chamber. After the upper powder feeding device sinters a working surface, the working surface moves down a layer thickness driven by the cylinder body. The upper powder feeding device slides down a certain amount of powder driven by the roller, and then the scraper flattens the powder to form a powder layer of precise thickness on the working surface. This reciprocating process forms a closed-loop sintering operation of the SLM process metal 3D printer with single-cylinder upper powder feeding. The disadvantages of the roller-feeding powder technology are: 1. The lower powder roller is equipped with a powder storage trough, and the powder in the powder trough is a discrete amount. When a powder trough rotates to the powder dropping position, all the powder in the powder trough falls together, making it difficult to achieve continuous and precise powder supply; 2. The roller and the powder trough are prone to sticking to powder, which causes the roller rotation to be obstructed and the powder to stick in the trough without falling. Summary of the Invention

[0005] In view of this, an object of the present invention is to provide an upper powder feeding mechanism for a metal 3D printer, which can achieve continuous and precise powder supply.

[0006] The technical solution adopted by the present invention to solve the technical problem is:

[0007] The powder feeding mechanism of the metal 3D printer includes a powder storage cabin, a partition is provided inside the powder storage cabin, and the partition divides the internal space of the powder storage cabin into an upper powder chamber and a lower powder chamber, the top of the powder storage cabin is provided with a powder adding port, the powder storage cabin is provided with a cover plate capable of opening and closing the powder adding port, a powder replenishing port is provided between the upper powder chamber and the lower powder chamber, the powder storage cabin is provided with a powder replenishing switch assembly capable of opening and closing the powder replenishing port, a base is provided at the lower end of the powder storage cabin, a powder outlet and a pull-out powder dropping switch assembly capable of opening and closing the powder outlet is provided on the base, an air pressure balancing pipe connected to the upper part of the lower powder chamber is connected to the outer wall of the powder storage cabin, the end of the air pressure balancing pipe can be inserted into the working cabin of the metal 3D printer to connect the lower powder chamber with the inner cavity of the working cabin, and the air pressure balancing pipe is provided with an air valve capable of controlling its on and off.

[0008] In a preferred embodiment of the invention, the gas valve is an electric valve or a solenoid valve, and a mounting position is provided on the powder storage cabin. A sensor capable of detecting the height of powder in the lower powder chamber is provided at the mounting position.

[0009] In a preferred embodiment of the invention, the powder replenishing switch assembly includes a first drawer door for closing the powder replenishing port, and a first driver capable of driving the first drawer door to move and open the powder replenishing port.

[0010] In a preferred embodiment of the invention, a guide rail for guiding the first sliding door is provided on the inner side wall of the powder storage compartment.

[0011] In a preferred embodiment of the invention, a bottom plate is fixed under the base, a powder drop port aligned with the powder outlet is provided on the bottom plate, a movable cavity is left between the bottom plate and the base, the pull-out type powder drop switch assembly includes a second pull-out door located in the movable cavity, the second pull-out door is provided with a powder guide groove connecting the powder outlet and the powder drop port, the second pull-out door is connected to a second driver that can drive it to move left and right so that the powder guide groove can be moved to a position staggered with the powder outlet.

[0012] In a preferred embodiment of the invention, the powder outlet, powder drop outlet, and powder guide groove are all long strip opening structures arranged along the front-to-back direction, the left-right width of the powder guide groove is greater than the left-right width of the powder outlet, and the left-right width of the powder guide groove is smaller than the left-right width of the powder outlet.

[0013] In a preferred embodiment of the present invention, a mounting groove is provided on the upper surface of the bottom plate, and a brush capable of brushing the lower surface of the second drawing door is provided in the mounting groove.

[0014] In a preferred embodiment of the invention, two vertical powder discharge grooves communicating with the movable cavity are provided on the bottom plate, and the two vertical powder discharge grooves are respectively located on the left and right sides of the powder drop port.

[0015] In a preferred embodiment of the invention, a flexible windproof structure arranged around the powder drop-out opening is provided on the lower surface of the bottom plate.

[0016] A metal 3D printer comprises a working cabin and an upper powder feeding mechanism according to any one of claims 1 to 9, wherein the powder storage cabin is fixed to the top of the working cabin, the top of the working cabin is provided with a powder feeding hole corresponding to the powder outlet, and when the powder outlet is opened, the lower powder chamber is connected to the inner cavity of the working cabin, and the end of the air pressure balance pipe is connected to the inner cavity of the working cabin.

[0017] The beneficial effects of the present invention are:

[0018] 1. When the upper powder feeding mechanism is used in a metal 3D printer, it can achieve continuous and precise powder supply, and there is no need to stop the machine during the process of adding powder to the upper powder chamber, which is conducive to improving work efficiency;

[0019] 2. The setting of the air pressure balance pipe can balance the pressure in the powder lowering chamber and the working chamber, avoiding powder backblowing caused by the pressure in the working chamber being higher than that in the powder lowering chamber;

[0020] 3. The arrangement of the flexible windproof structure can form a powder discharge channel, which can prevent the circulating wind field in the working cabin from disturbing the powder during the falling process and causing powder splashing to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a perspective view of the present invention;

[0022] Figure 2 It is a cross-sectional view of the first working state of the present invention;

[0023] Figure 3 is a cross-sectional view of the second working state of the present invention;

[0024] Figure 4 This is a three-dimensional diagram of the present invention without the cover plate;

[0025] Figure 5 It is an exploded view of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0027] It should be noted that all directional indications in this invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative positional relationships and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly. In addition, the descriptions of "preferred" and "less preferred" in this invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "preferred" or "less preferred" may explicitly or implicitly include at least one such feature.

[0028] Reference Figures 1 to 5 The present invention proposes an upper powder feeding mechanism of a metal 3D printer, including a powder storage cabin 100, characterized in that a partition 101 is provided inside the powder storage cabin 100, and the partition 101 divides the internal space of the powder storage cabin 100 into an upper powder chamber 102 and a lower powder chamber 103, a powder adding port 104 is provided on the top of the powder storage cabin 100, and a cover 105 capable of opening and closing the powder adding port 104 is provided on the powder storage cabin 100, a powder replenishing port 106 is provided between the upper powder chamber 102 and the lower powder chamber 103, and a powder replenishing port 106 capable of opening and closing the powder replenishing port 104 is provided on the powder storage cabin 100. 6, a powder replenishing switch assembly, a base 108 is provided at the lower end of the powder storage cabin 100, a powder outlet 109 and a pull-out powder dropping switch assembly 110 capable of opening and closing the powder outlet 109 are provided on the base 108, an air pressure balance pipe 111 connected to the upper part of the lower powder chamber 103 is connected to the outer wall of the powder storage cabin 100, the end of the air pressure balance pipe 111 can be inserted into the working cabin of the metal 3D printer to connect the lower powder chamber 103 with the inner cavity of the working cabin, and an air valve 112 capable of controlling its on and off is provided on the air pressure balance pipe 111.

[0029] When the upper powder feeding mechanism is used on a metal 3D printer, the powder storage cabin 100 is fixed on the top of the working cabin. The top of the working cabin is provided with a powder feeding hole corresponding to the powder outlet 109. When the powder outlet 109 is opened, the lower powder chamber 103 is connected to the inner cavity of the working cabin, and the end of the air pressure balance pipe 111 passes through the top wall or side wall of the working cabin and is connected to the inner cavity of the working cabin.

[0030] Preferably, the air valve 112 is an electric valve or a solenoid valve, and the powder storage compartment 100 is provided with a mounting position 113, at which a sensor capable of detecting the powder height in the lower powder chamber 103 is provided. The sensor can be a distance sensor capable of detecting the powder height, a photoelectric sensor capable of detecting whether the powder height line is lower than a set position, or a weighing sensor capable of weighing the powder in the lower powder chamber 103.

[0031] Before starting the metal 3D printer, an appropriate amount of metal powder is added to both the upper powder chamber 102 and the lower powder chamber 103 of the powder storage compartment 100. During operation, the powder outlet 109 on the base 108 is intermittently opened to continuously add powder to the 3D printer. The operation of the upper powder feeding mechanism includes the following stages:

[0032] 1. During the pressure balance phase, the cover 105 on the top of the powder storage compartment 100 is closed, and the air valve 112 on the pressure balance pipe 111 is opened to balance the air pressure in the lower powder chamber 103 with the air pressure in the working compartment of the 3D printer.

[0033] 2. During the powder dropping stage, the powder outlet 109 is opened to allow the metal powder in the lower powder chamber 103 to fall into the working chamber. Since the width of the powder outlet 109 is fixed and the pressure in the lower powder chamber 103 is balanced with that in the working chamber, powder backblowing caused by the pressure in the working chamber being greater than that in the lower powder chamber 103 is avoided. Therefore, when the total amount of metal powder in the lower powder chamber 103 exceeds a certain threshold, the flow rate of powder falling from the powder outlet 109 is basically unchanged. Therefore, the pull-out powder dropping switch assembly 110 controls the opening time of the powder outlet 109 to achieve precise powder dropping amount control.

[0034] 3. In the powder replenishing stage, when the total amount of metal powder in the lower powder chamber 103 is lower than the set value, the powder replenishing port 106 is opened, and the metal powder in the upper powder chamber 102 falls into the lower powder chamber 103, so that the total amount of powder in the lower powder chamber 103 is kept above the threshold value, and the flow rate of the powder falling from the powder outlet 109 remains basically unchanged.

[0035] 4. Powder Addition Stage: After the 3D printer has been operating for a period of time, the amount of metal powder in the upper powder chamber 102 decreases significantly. At this point, the powder replenishment port 106 needs to be closed to separate the lower powder chamber 103 from the upper powder chamber 102. The cover 105 of the upper powder chamber 102 is then opened to add powder to the upper powder chamber 102. Although the upper powder chamber 102 is open, it does not affect the air pressure in the lower powder chamber 103. The air pressure in the lower powder chamber 103 is in equilibrium with the air pressure in the working chamber, which does not affect the powder drop at the powder drop port, allowing the 3D printer to continue operating normally. After the upper powder chamber 102 is fully filled with powder, the cover 105 is closed to form a seal.

[0036] 5. In the secondary powder replenishing stage, since the powder outlet 109 is intermittently opened to add powder to the working chamber, the powder replenishing port 106 can be opened after the powder outlet 109 is closed to replenish powder into the lower powder chamber 103. At the same time, under the action of the air pressure balance pipe 111, the air pressure in the lower powder chamber 103, the upper powder chamber 102 and the working chamber can all reach air pressure balance.

[0037] 6. By cycling through the above-mentioned steps 2 to 5, continuous and precise powder supply can be achieved, and there is no need to stop the machine during the process of adding powder to the upper powder chamber 102, which is conducive to improving work efficiency.

[0038] In a preferred embodiment of the present invention, the powder replenishment switch assembly includes a first drawable door 115 that seals the powder replenishment port 106, and a first actuator 116 capable of driving the first drawable door 115 to move and open the powder replenishment port 106. The first actuator 116 can be a pneumatic cylinder, an electric push rod, or other device, with a pneumatic cylinder being preferred. To guide the first drawable door 115, a guide rail 117 is provided on the inner sidewall of the powder storage compartment 100. The first drawable door 115 is provided with a slide groove 1151 that slidably engages with the guide rail 117.

[0039] The powder supply port 106 may be provided on one side of the partition 101 or on the partition 101 .

[0040] In the above scheme, the partition 101 and the first sliding door 115 are both flat plates and are parallel to each other. In order to improve the sealing of the first sliding door 115, a sealing strip can be set between the first sliding door 115 and the right inner wall of the powder storage compartment 100. In addition, the upper surface of the first sliding door 115 needs to be in close contact with the lower surface of the partition 101.

[0041] In certain embodiments of the present invention, the powder replenishing switch assembly may also adopt other structural forms, for example, a door panel that can be flipped open and closed and a motor that can drive the door panel to rotate and open.

[0042] In a preferred embodiment of the present invention, a bottom plate 118 is fixed below the base 108. A powder drop port 119 aligned with the powder outlet 109 is provided on the bottom plate 118. A movable cavity is left between the bottom plate 118 and the base 108. The pull-out powder drop switch assembly 110 includes a second pull-out door 121 located in the movable cavity. The second pull-out door 121 is provided with a powder guide groove 122 connecting the powder outlet 109 and the powder drop port 119. The second pull-out door 121 is connected to a second driver 123 capable of driving it to move left and right so that the powder guide groove 122 can be moved to a position staggered with the powder outlet 109. The second driver 123 can be a device such as a cylinder or an electric push rod, with a cylinder being the most preferred.

[0043] In the above scheme, the powder outlet 109, the powder drop outlet 119, and the powder guide groove 122 are all long strip opening structures arranged along the front-to-back direction. The left-right width of the powder guide groove 122 is greater than the left-right width of the powder outlet 109, and the left-right width of the powder guide groove 122 is less than the left-right width of the powder drop outlet 119. When the powder outlet 109, the powder drop outlet 119, and the powder guide groove 122 are aligned, the powder in the lower powder chamber 103 can fall normally through the powder outlet 109, the powder guide groove 122, and the powder drop outlet 119. When the second sliding door 121 moves to a position that offsets the powder guide groove 122 from the powder outlet 109, the second sliding door 121 closes the powder outlet 109. At this time, the powder in the lower powder chamber 103 cannot fall. The left and right widths of the powder guide groove 122 are set to be larger than the width of the powder outlet 109, and the width of the powder drop outlet 119 is set to be larger than the width of the powder guide groove 122. This can prevent the powder from being affected by the inner wall of the powder guide groove 122 and the inner wall of the powder drop outlet 119 when falling, thereby reducing the powder falling speed, so that the flow rate of the falling powder can always be maintained within the set range, thereby achieving continuous and precise powder supply.

[0044] Furthermore, the upper surface of the bottom plate 118 is provided with a mounting groove 124, which houses a brush (not shown) capable of scrubbing the lower surface of the second drawer door 121. This brush removes metal powder from the lower surface of the second drawer door 121 as it moves sideways, significantly reducing the risk of powder becoming stuck between the second drawer door 121 and the bottom plate 118. Preferably, the mounting groove 124 is annular, with the brush arranged around the upper end of the blanking port.

[0045] Furthermore, two vertical powder discharge grooves 126 are provided on the bottom plate 118, communicating with the movable chamber. The two vertical powder discharge grooves 126 are located on the left and right sides of the powder outlet 119. The arrangement of the vertical powder discharge grooves 126 can discharge powder between the second drawer door 121 and the bottom plate 118, further reducing the occurrence of powder jamming between the second drawer door 121 and the bottom plate 118.

[0046] Furthermore, the lower surface of the base plate 118 is provided with a flexible windproof structure 127 arranged around the powder drop opening 119. Flexible windproof structure 127 adopts a brush-like structure, with a rigid metal or plastic ring as the mounting ring. The mounting ring is filled with flexible bristles. These bristles naturally droop to form a powder drop channel, thereby preventing the circulating wind field in the working chamber from disturbing the powder during the falling process, thereby causing powder splashing.

[0047] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made based on the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A powder feeding mechanism of a metal 3D printer, comprising a powder storage cabin (100), characterized in that: The powder storage cabin (100) is provided with a partition (101) inside, and the partition (101) divides the internal space of the powder storage cabin (100) into an upper powder chamber (102) and a lower powder chamber (103). The top of the powder storage cabin (100) is provided with a powder adding port (104). The powder storage cabin (100) is provided with a cover plate (105) capable of opening and closing the powder adding port (104). A powder replenishing port (106) is provided between the upper powder chamber (102) and the lower powder chamber (103). The powder storage cabin (100) is provided with a powder replenishing switch assembly capable of opening and closing the powder replenishing port (106). A base (108) is provided at the lower end of the powder storage cabin (100), and a powder outlet (109) and a pull-out powder drop switch assembly capable of opening and closing the powder outlet (109) are provided on the base (108); an air pressure balance pipe (111) communicating with the upper part of the lower powder chamber (103) is connected to the outer wall of the powder storage cabin (100); the end of the air pressure balance pipe (111) can be inserted into the working cabin of the metal 3D printer to connect the lower powder chamber (103) with the inner cavity of the working cabin; and an air valve (112) capable of controlling the opening and closing of the air pressure balance pipe (111) is provided on the air pressure balance pipe (111).

2. The upper powder feeding mechanism of the metal 3D printer according to claim 1, characterized in that: The air valve (112) is an electric valve or a solenoid valve. The powder storage cabin (100) is provided with a mounting position (113). A sensor capable of detecting the height of powder in the lower powder chamber (103) is provided at the mounting position (113).

3. The upper powder feeding mechanism of the metal 3D printer according to claim 1, characterized in that: The powder replenishing switch assembly comprises a first drawer door (115) for closing the powder replenishing port (106), and a first driver (116) capable of driving the first drawer door (115) to move and open the powder replenishing port (106).

4. The upper powder feeding mechanism of the metal 3D printer according to claim 3, characterized in that: A guide rail (117) for guiding the first drawer door (115) is provided on the inner side wall of the powder storage compartment (100).

5. The upper powder feeding mechanism of the metal 3D printer according to claim 1, characterized in that: A bottom plate (118) is fixed below the base (108), and a powder drop port (119) aligned with the powder outlet (109) is provided on the bottom plate (118), and an active cavity is left between the bottom plate (118) and the base (108), and the pull-out type powder drop switch assembly includes a second pull-out door (121) located in the active cavity, and a powder guide groove (122) connecting the powder outlet (109) and the powder drop port (119) is provided on the second pull-out door (121), and the second pull-out door (121) is connected to a second driver (123) capable of driving it to move left and right so that the powder guide groove (122) can move to a position offset from the powder outlet (109).

6. The upper powder feeding mechanism of the metal 3D printer according to claim 5, characterized in that: The powder outlet (109), the powder drop outlet (119), and the powder guide groove (122) are all long strip opening structures arranged along the front-to-back direction, the left-right width of the powder guide groove (122) is greater than the left-right width of the powder outlet (109), and the left-right width of the powder guide groove (122) is less than the left-right width of the powder drop outlet (119).

7. The upper powder feeding mechanism of the metal 3D printer according to claim 5 or 6, characterized in that: The upper surface of the bottom plate (118) is provided with a mounting groove (124), and a brush (125) capable of brushing the lower surface of the second drawing door (121) is provided in the mounting groove (124).

8. The upper powder feeding mechanism of the metal 3D printer according to claim 6, characterized in that: Two vertical powder discharge grooves (126) communicating with the active cavity are provided on the bottom plate (118), and the two vertical powder discharge grooves (126) are respectively located on the left and right sides of the powder drop port (119).

9. The upper powder feeding mechanism of the metal 3D printer according to claim 5 or 6, characterized in that: The lower surface of the bottom plate (118) is provided with a flexible windproof structure (127) arranged around the powder dropping port (119).

10. A metal 3D printer, characterized in that: It comprises a working cabin and an upper powder feeding mechanism as described in any one of claims 1 to 9, the powder storage cabin (100) is fixed on the top of the working cabin, the top of the working cabin is provided with a powder feeding hole corresponding to the powder outlet (109), when the powder outlet (109) is opened, the lower powder chamber (103) is connected to the inner cavity of the working cabin, and the end of the air pressure balance pipe (111) is connected to the inner cavity of the working cabin.

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