CN107433714B

CN107433714B - Special fusion micro-comb powder spreading method and powder spreading device for powder 3D printing

Info

Publication number: CN107433714B
Application number: CN201710336340.5A
Authority: CN
Inventors: 请求不公布姓名
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-05-25
Filing date: 2017-05-13
Publication date: 2024-03-19
Anticipated expiration: 2037-05-13
Also published as: CN107433714A

Abstract

A special fusion micro-comb powder spreading method for powder 3D printing and a printer thereof belong to the field of machinery. A powder falling process, a powder overflow removing micro-carding powder spreading process or a powder overflow reserving micro-carding powder spreading process are integrated; the method comprises the step of using a fusion groove with linear gradual change of cross section characteristics, and is structurally characterized in that a shovel-shaped structure of a comb-shaped powder scraping sheet is utilized, a front edge part is processed into a thinner comb-shaped sawtooth-shaped plane curve, and the plane of the curve is overlapped with the surface of a molding bin opening; the comb-shaped powder scraping sheet slides on the surface of the molding bin opening, and the tips of the saw teeth just enable redundant powder to be separated towards the two sides of the tooth tips so as to fill a powder falling-free area of selective powder falling; compared with the prior art, the invention has the most important advantages of simple structure, high efficiency, capability of improving the efficiency by more than 2-3 times and popularization and application values.

Description

Special fusion micro-comb powder spreading method and powder spreading device for powder 3D printing

[ technical field ]

The invention belongs to the technical field of machinery, and particularly relates to a rapid layer-by-layer powder spreading method special for laser sintering and spray-sticking type 3D printing.

[ background Art ]

At present, a 3D printer for sintering powder layer by layer and bonding powder layer by layer is increasingly used as an important means for industrial processing, the powder paving technology and device directly influence the printing speed and printing quality of a workpiece, most of powder paving devices of the existing powder 3D printer are provided with a piston bin type powder storage device capable of lifting and a falling powder type powder supply device, the powder paving devices collect or fall powder in front of a flat powder scraping sheet, a mound-shaped strip-shaped powder pile with a layer thickness of dozens of layers is piled up, then the powder scraping sheet (also called a scraper) is required to push the powder pile horizontally to uniformly spread powder, and the powder pile can possibly shift a tiny forming structure of a shallow part of a forming bin without a firm foundation when the powder pile is too high or the powder paving speed is too high, so that the scraper speed is required to be reduced, the process is long even 40 seconds to 2 minutes for a medium printing scale forming machine, and the powder paving speed is slow and the efficiency is low.

Detailed description of the technical background: three-dimensional printing (3 dp) is mainly powder bond molding. The specific process of 3DP is as follows: after each layer is bonded, the forming cylinder is lowered a distance (equal to the layer thickness), the powder supply cylinder is raised a certain height, excess powder is pushed out, and the powder is pushed to the forming cylinder by the powder spreading roller, spread and compacted. The spray head moves according to the two-dimensional geometric information of the next section under the control of a computer, selectively sprays the adhesive, and finally forms a layer. The principle is very similar to that of a printer, namely the name of three-dimensional printing is obtained. The powder collecting device collects the excessive powder when the powder spreading roller spreads the powder. The powder is sent, spread and sprayed repeatedly, and finally the three-dimensional powder is bonded, so that the product is produced.

The 3DP technology is mature. In 1989, emanual Sachs et al, the university of Massachusetts, U.S. Pat. No. 3DP patent, one of the core patents in the category of droplet ejection forming of non-forming materials. Manufacturers using 3DP technology, mainly ZC corporation (3 DSystems 2011), ex-One, rikon institute, japan, zprinter, R-series three-dimensional printers. The israel objectgeometry (Stratasys 2012) in 2000 introduced a printing device Quadra based on a combination of 3Dink-Jet and SLA processes. The 3DP printing apparatus can use a large amount of materials including gypsum, plastic, ceramic, metal, etc., and can print color parts, enabling the formation of parts having complex shapes inside. Such printers increase speed by multiple heads and nozzles. In domestic aspects, the university of Qinghua, the university of western security traffic, shanghai university and the like are also actively researched and developed. The 3DP molding speed is high, and a color prototype can be made. The 3DP technology has high molding speed and low molding material price, and is suitable for being used as a desktop type rapid molding device. Meanwhile, as pigment is added in the binder, a color prototype can be manufactured, which is one of the most competitive characteristics of the process. The whole forming process does not need to be supported, the removal of the redundant powder is more convenient, and the method is particularly suitable for making a prototype with a complex inner cavity. Of course, because the 3DP molded part has low strength, only a conceptual model can be made, but a functional test part cannot be made. The 3DP technology has been widely used in foreign household appliances, automobiles, aerospace, marine, industrial design, medical, and other fields. Currently, the mainstream full-color 3D portrait printing in the market mostly adopts the 3DP technology.

The metallic 3D printing SLS technology is the most leading and potential technology in 3D printing systems. Along with the demands of technological development and popularization and application, the direct manufacture of metal functional parts by rapid prototyping becomes a main development direction of rapid prototyping. The rapid prototyping method for directly manufacturing metal functional parts at present mainly comprises the following steps: laser net shape (LENS, laserEngineeredNetShaping), selective laser sintering (SLS, selectiveLaserSintering) and selective laser melting (SLM, selectiveLaserMelting, SLM), direct metal laser sintering (DMLS, directMetalLaserSintering), and electron beam melting techniques (EBM, electronBeamMelting), among others. The SLS technology uses a laser as an energy source, and uniformly sinters powder on a processing plane by a laser beam. A layer of very thin (sub-millimeter level) powder is uniformly paved on a workbench as a raw material, and a laser beam is scanned according to layered two-dimensional data by a scanner at a certain speed and energy density under the control of a computer. After scanning by the laser beam, the powder at the corresponding position is sintered into a solid sheet with a certain thickness, and the loose powder state is still maintained at the non-scanning position. After this layer is scanned, the next layer needs to be scanned. And repeating the steps until all the layers are scanned. And removing excessive powder, polishing, drying and other appropriate post-treatments to obtain the part. The SLS technique is suitable for complex part fabrication. The SLS technology was first proposed by CarlDeckard and JoeBeaman, ostin of Texas university, 1989, and later established the DTM company and began the SLS commercial product SinterSation in 1992. In 2001, 3DSystems purchased DTM, and completed the technology integration. SLS treatable raw materials include plastic powders (nylon, polystyrene, polycarbonate, etc., direct laser sintering), metal powders (direct process, indirect process, and two-member process), ceramic powders (binders including inorganic binders, organic binders, and metal binders are used). SLS has been successfully applied in many industries, such as automotive, shipbuilding, aerospace, and aviation. In addition to DTM company, germany EOS company has developed a corresponding series of molding equipment. In China, such as university of North China, north China institute of technology and North China, beijing automatic forming limited company and the like, a great deal of important results are achieved, such as an RAP-I type laser sintering rapid forming system developed by the university of North China, AFS-300 laser rapid forming equipment developed by the Beijing automatic forming limited company and the like. SLS has been successfully applied to a plurality of industries such as automobiles, shipbuilding, aerospace and aviation at present, and mainly relates to links such as rapid prototype manufacturing, rapid mould and tool manufacturing, small-batch production and the like.

[ summary of the invention ]

The purpose of the invention is that:

the method aims to solve the problems and improve: the powder spreading speed is very low, the structure is complex, the efficiency is low, and the like.

The invention realizes the above purpose through the following technical scheme:

comprising the following steps: the process of fusion powder falling, the process of micro-combing powder spreading and the rolling process (the rolling can be used optionally).

Fusion powder falling process:

the main structure is as follows: a fusion powder supply roller, a powder falling sheet, a powder supply motor, a powder storage bin and the like; the fusion powder falling process comprises the following steps: the powder feeding motor and the fusion powder feeding roller are driven to rotate to bring the stored powder in the powder storage bin to the bottom through the self fusion groove space, and the fusion groove carrying the powder is a closed space when contacting the powder falling sheet, so that the self thrust of the powder pushes the powder falling sheet away, and the powder falls down; the number of the powder falling sheets is as large as the number of the groove groups of the fusion grooves, the grooves of the same group are distributed on the same circumference, and the number of the grooves is 2 or more than 2; the other group is distributed on the other circumference, and the number of the grooves is 2 or more than 2; positional relationship of all grooves: seen along the axis direction of the fusion powder supply roller, 2 groups are sequentially overlapped end to end and are divided into an overlapped area and a single groove area; the cross section of the fusion groove is characterized in that the cross section of the groove is unchanged in a non-coincident region and the cross section is the same, the cross section gradually decreases until reaching zero in the coincident region, namely the depth of the groove gradually decreases to zero in the coincident region; the powder is discharged from the single groove and the single powder falling sheet in the non-overlapping area, and the powder is discharged from the double groove and the double powder falling sheet simultaneously in the overlapping area, wherein the quantity of the discharged powder is equal to the sum of the discharged powder of the double powder falling sheets. Thus, an absolute linear output of the powder is theoretically obtained, which is absolutely inexorable in the volumetric variable displacement pump technology-! Thus, 1 powder falling area with controllable powder amount and uniform powder falling is formed.

The other function of the powder falling sheet is that when the fusion powder supply roller stops rotating, the elastic force is recovered to enable the powder falling sheet to seal the section of the fusion groove, and the falling of powder is instantaneously stopped; the powder falls into the forming cylinder through the hopper to form a plurality of strip-shaped powder dwarf walls, and the middle branching lines of the dwarf walls are just overlapped with the straight line track running by the tooth-shaped front edges of the comb-shaped powder scraping sheets, so that the preparation is made for carding and flattening.

* Further, the above-mentioned uniform powder-falling areas can be set in plural on the same fusion powder-feeding roller, each uniform powder-falling area contains even groups of groove groups of 2 groups, 4 groups, etc., which are present in pairs, and every 1 pair must have the above-mentioned fusion characteristics.

* Further, the shape of the groove cross section: the powder falling sheet can be trapezoidal, rectangular and arc-shaped, is optimally in a shape with a narrow lower part and a wide upper part, has self compensation function when being slidingly matched with a contact point of the powder falling sheet in the shape with the narrow lower part and the wide upper part, and has little influence on sealing due to abrasion without influencing a fit clearance.

And (3) a micro-carding powder spreading process:

the method comprises the steps of powder overflow removal and powder paving or powder overflow remaining and powder paving:

the process of removing powder and spreading powder, namely, the process of selectively or uniformly dropping powder to a forming cylinder, then scraping powder by using a comb-shaped powder scraping sheet which has a shovel-shaped appearance and is processed with a tooth-shaped front edge and simultaneously sweeping powder accumulated in a powder overflow area; the tooth-shaped front edge of the shovel-shaped appearance is beneficial to reducing the resistance of the powder pile to the powder scraping sheet, which is similar to the water diversion effect of the head of the ship, has small mechanical interference to the deep part of the forming bin, and can greatly improve the powder spreading speed.

The process of powder remaining and spreading, namely, after selectively or uniformly falling powder, a forming cylinder is scraped by using a comb-shaped powder scraping sheet which has a shovel-shaped appearance and is processed with a tooth-shaped front edge, or directly spreading powder by using a straight powder scraping sheet, wherein the straight powder scraping sheet is one of the most used scraping plate shapes at present; the powder quantity and uniformity can be well controlled in the powder dropping process, so that excessive powder can not be accumulated in front of the flat powder scraping sheet, disturbance to a paved powder layer is reduced, the powder dropping height is improved, or a convex column is added at the surface of a powder dropping channel of a mechanical vibration or funnel so as to disturb the falling of the powder, and the powder is uniformly dropped in front of the flat powder scraping sheet as much as possible.

After the powder spreading processes (only part of one powder spreading period) are finished, the period is finished after the laser sintering molding or the glue spraying molding process is carried out; then the piston on the forming cylinder descends one layer of height again, the powder supply cylinder piston of the powder supply cylinder is lifted by 1 layer of height again, and then the next round of forming process is carried out, and the process is repeated.

The comb-shaped powder scraping sheet has the structural characteristics that:

the essential characteristics are a shovel-shaped appearance structure, and the front edge part is processed into a thin comb shape and has a sawtooth shape; the tip part is thinner, the structure far away from the tip part is thicker, the contact line of the powder layer with the surface of the forming cylinder is a sawtooth-shaped curve, the sawtooth-shaped curve has a certain width (about 1/10-100 mm) and is a plane curve, the plane of the curve coincides with the surface of the forming bin mouth, the shovel-shaped appearance is suitable for shoveling powder, the impact on the forming powder layer in the previous period is smaller, the resistance is also small, and the powder layer is suitable for rapid carding. The comb-shaped powder scraping sheet slides on the surface of the forming bin opening, powder higher than the surface of the forming bin opening is shoveled like a snow shovel, and the tips of the saw teeth just enable redundant powder to be separated towards the two sides of the tooth tips so as to fill a powder falling-free area of selective powder falling.

* Furthermore, the vibrator is used for vibrating the comb-shaped part at the front edge of the comb-shaped powder scraping sheet on the structure of the comb-shaped powder scraping sheet, so that powder contacted with the comb-shaped powder scraping sheet is easy to slide and add, the impact force on powder of a forming cylinder can be further reduced, and the resistance is smaller.

* Further, the saw tooth root portion of the spade-shaped saw tooth suitable for spading powder can be processed with a residual powder channel running along the translation direction, so that powder separated by the tooth tip portion and sliding accumulated to the tooth root portion during spading powder is not excessively accumulated, and is transferred along the residual powder channel, and the residual powder is removed at the end of powder laying or actively.

* Further, the synchronous powder sweeping and discharging process refers to: powder in a powder overflow area (13) accumulated in the powder scraping process of the comb-shaped powder scraping sheet is moved out of a toothed area at the front end of the comb-shaped powder scraping sheet in time through a spiral brush or a powder suction device or a displacement powder scraping plate or a powder blowing device and the like; the structure of the spiral brush is that bristles are rooted on a cylinder, the direction of the bristles points to the radial direction, and the whole cylinder is not fully covered with bristles, but spirally distributed or purely axially distributed on the cylinder; the powder suction device is structurally characterized in that a pipeline is used for sucking redundant powder; the structure of the displacement powder scraping plate is a spiral body or a translational sheet-shaped object; the structure of the powder blowing device is that a pipeline is used for blowing off redundant powder; it should be noted that: removing excess powder by transporting it out of the forming cylinder or re-spreading it over a large area of the forming cylinder surface not being scraped; the problem of pits of shearing force between powder bodies can be generated when the powder is scraped at high speed when the powder overflow area (13) is excessively filled, and even the suspension formed object body of the upper layer is pushed.

* Further, the uniformity powder falling process refers to: uniformly falling powder in the vertical direction of the comb-shaped powder scraping sheet, wherein the powder quantity falls once or repeatedly; with respect to the uniform powder falling process, the selective powder falling refers to a strip-shaped area of a front edge tooth tip running path of the comb-shaped powder scraping sheet for falling powder on the forming cylinder, and the width of the strip-shaped area is smaller than the interval between the front edge tooth tips of the comb-shaped powder scraping sheet, so that the powder falling area is necessarily present, and therefore, a powder strip exceeding the thickness of a layer needs to be accumulated in the strip-shaped area, and the following needs to be pointed out: the meaning of selective powder falling is that the requirement on the fine control degree of powder falling is greatly reduced, because any conventional machine cannot accurately form the thickness of the powder falling layer into the target thickness at one time, powder can only be piled excessively, and hidden danger is caused to disturbance formed objects during powder scraping; the area outside the strip-shaped area of the running path of the front edge tooth tip part of the comb-shaped powder scraping sheet is free of powder falling or only small amount of powder falling; the powder falling mechanism is a funnel-shaped through hole at the lower end, and the through hole uses a valve structure to enable powder to fall or prevent falling and falling speed.

The invention has the beneficial effects that:

compared with the prior art, the invention has the advantages of simple structure, greatly accelerated powder spreading speed, capability of improving the powder spreading speed by more than 2-3 times, and popularization and application values.

[ description of the drawings ]

The invention is further described with reference to the preferred embodiments in the following with reference to the accompanying drawings:

fig. 1 is a schematic diagram of a principle of a powder falling sheet and a cylindrical rotor type powder falling device.

Fig. 2 is a schematic diagram of a cone-shaped rotor type powder falling device for fusing powder falling sheets.

Fig. 3 is a schematic diagram of a special micro-comb quick powder spreading method for laser sintering and spray-bonding type 3D printing.

Fig. 4 schematic diagram of special fusion micro-comb powder spreading device for powder 3D printing

Description of the reference numerals:

(1) Fusion rotor

(2) Structural cavity

(3) Thrust spring piece

(4) Powder falling tablet

(5) Leaning wall

(6) Fixing screw

(7) Powder material inlet

(8) Powder outlet

(9) Vacuum inhalation powder

(10) Discharged powder

(11) Rotating shaft

(12) 2 channels with the same circumference

(13) Another 2 channels with the same circumference

(14) One-way pressure release valve

(15) Pressure relief duct

(20) Channel overlapping portion

(21) Powder inlet shape

(22) Powder outlet shape

(41) (42) powder falling tablet

(51) Comb-shaped powder scraping sheet

(52) Comb-shaped teeth of powder scraping sheet

(53) Forming cylinder

(54) Powder return brush

(55) Powder return brush shaft

(56) Powder return motor

(57) Rotary axle center of back brush

(58) Circumferential track of back painting

(59) Wedge-shaped front edge of brush for back painting

(60) Powder surface after powder spreading

(61) Selective powder fall region

(62) Areas without powder falling

(63) Powder overflow area

(64) Direction of scraping powder

(65) Comb-shaped powder scraping sheet reduced full view

(66) Reduced overall view of back painting

(70) Fusion powder supply roller

(71) Powder storage bin

(72) Powder falling tablet

(73) Powder supply motor

(74) Fusion groove

(75) Guide rail

(76) Powder pressing roller

(77) Fusion powder falling area

(78) Support frame

(79) Powder spreading funnel

(80) Fixing screw

(81) Residual powder channel

(82) Powder storage bin/cavity stripping part

(83) Motor shaft

(84) Powder falling gap

(85) Powder storage

[ example ]

As shown in fig. 1:

the left hand side of the figure is a detailed illustration of the fusion rotor (1) moving out; a total of 4 channels, 2 identical circumferential channels (12) and 2 other identical circumferential channels (13); the length of each channel is slightly more than 1/8 of the circumference radian; namely 45 degrees; there is thus a channel overlap (20) with an angle of about 10-20 degrees.

The right side of the figure is a perspective view of the whole oil pump seen along the direction of the rotating shaft (11) of the fusion rotor (1), and the superposition part (20) of the 4 channel distribution perspective viewing channels is clearly visible, namely, 2 identical circumference channels (12) and the other 2 identical circumference channels (13) are respectively and oppositely distributed (180 degrees); the center point of each channel is at an angle of 90 degrees to ensure that the entire circumference is filled with channels and that there are 4 identical overlapping areas.

The powder falling sheet (41) and the powder falling sheet in the figure 2 are fastened on the structural cavity (2) by the fixing screw (6), the parts are basically the same (see the description of figure 2 in detail), and the leaning wall (5) is tightly contacted with the back of the powder falling sheet (41); ensure that the channel ≡! (7) (8) respectively a powder input port and a powder output port; (9) powder material sucked in by vacuum; the graph shows that the powder sucked in by vacuum is instant; (10) In practical cases, the powder is filled in the whole inlet and outlet space, and the action principle of feeding and discharging is conveniently expressed in the figure and is not shown.

When used as a hydraulic motor: the one-way pressure release valve (13) will function: in a short time of starting the motor, the channel cannot reach full vacuum instantaneously, the phenomenon of channel oil trapping occurs back, full torque cannot be generated, and starting cannot be performed. The pressure relief port (14) may be vented to a low pressure oil area or to the outside of the engine.

(21) The shape of the circular powder input port is adopted; (22) The shape of a square powder outlet is adopted, and the powder is drawn in from the hole; only all channels are visible, since each channel has only about 1/8 of a circular arc, and is sealed for oil pressure input in any position of the fusion rotor (1). (22) Is favorable for fixedly mounting the powder falling sheet (41),

due to the sealing of the contact sliding area, 1 plane leaning wall is needed, and the powder falling sheet (41) is convenient to fixedly install.

According to the rotation direction of an arrow in the figure, the upper powder falling sheet (41) in the figure is kept in surface contact with the fusion rotor (1) due to the action of surface dragging, one is contacted with the bottom of the channel, and the vacuum state of the channel on the right side is formed (a closed space surrounded by 3 surfaces: the surface of the channel, the surface of the tip contact part of the powder falling sheet (41) and the inner surface on the structural cavity (2)); the other has slid off the side area on which the channel contacts, the tip being displaced a distance.

As shown in fig. 2:

in principle, the fusion rotor (1) is completely identical to fig. 1, with the difference that it is cone-shaped. The sealing is different from the situation of fig. 1, and the fusion rotor (1) is tightly matched with the inner surface of the structural cavity (2) under the upper thrust of the thrust spring piece (3), so that the sealing is excellent.

The lower right corner is an enlarged oblique view of the powder falling sheet (4), and the shape and the working mode of the powder falling sheet are easy to show; after the fixing screw (6) is fastened, the fixing screw tightly leans against the leaning wall (5) and is exactly aligned to the circumference where the 2 groups of channels are positioned; the annular bending of the powder falling sheet (4) is easy to generate displacement along the normal direction of the conical surface of the fusion rotor (1); along with the rotation of the fusion rotor (1), the contact end of the powder falling sheet (4) and the fusion rotor (1) are clung to the surface to slide, and when the powder falling sheet slides out of the channel.

The diagram right below is a disassembled part diagram of the structural cavity (2), and (7) and (8) are respectively a powder input port and a powder output port; the upper drawing in the figure is a sectional view of the entire oil pump viewed along the direction perpendicular to the rotation shaft (11) of the fusion rotor (1); as in fig. 1; the 2 same circumference channels (12) and the other 2 same circumference channels (13) are respectively distributed (180 degrees) relatively.

(21) (22) circular powder inlet and powder outlet shapes, respectively, from which the powder is viewed; only all channels are visible, since each channel has only about 1/8 of a circular arc, and is sealed for oil pressure input in any position of the fusion rotor (1).

The cross-sectional variation characteristics of the channels are described in detail in the summary of the invention.

As shown in fig. 3:

the powder scraping device is dragged by a powder spreading motor, the powder contact part of the powder scraping device is a comb-shaped powder scraping sheet (51), and the comb-shaped powder scraping sheet (51) horizontally moves along a powder scraping direction (64) and sweeps on the surface of a forming cylinder (53); the whole graph (65) is reduced by comparing the comb-shaped powder scraping sheet, so that a powder overflow area (63) generated in the actual powder scraping process can be seen; the height of the powder surface of the powder falling-off area (62) is slightly lower than the upper surface of the forming cylinder (53) by 0.1-3 mm (the height difference is formed by the fact that a piston in the forming cylinder descends after one forming cycle is completed), the selective powder falling-off area (61) is a strip-shaped area, the height of powder accumulation is slightly protruded between the upper surface 01-3 mm of the forming cylinder (53), a path travelled by a wedge-shaped front edge (59) of the powder scraping sheet is located at the center line position, the wedge-shaped front edge of the comb-shaped tooth (52) of the powder scraping sheet enables the selective powder falling-off area (61) of the strip-shaped area to be divided into 2 sides, the powder shortage area of the powder falling-off area (62) is just filled, excessive accumulation of the powder overflow area (63) is swept by a powder returning brush (54), and a circumference track (58) of the powder returning brush can just sweep to the accumulated powder without contacting the surface position of the forming cylinder (53), and the following details: the back painting is shown in a reduced full graph (66); a powder return motor (56) is fixed on the powder scraping device and drives a powder return brush shaft (55) to rotate around a powder return brush rotating shaft center (57); the powder surface (60) after powder spreading can be compacted by a powder compacting roller and is a flat surface flush with the surface of the forming cylinder (53).

The powder falling process is completed by a powder spreading hopper, and the scraped excessive powder can be recovered by a powder returning bin for reuse; the tooth-shaped front edge of the shovel-shaped appearance is favorable for reducing the resistance of the powder pile to the powder scraping sheet, and the action is similar to the water diversion effect of the head part of the ship, so that the mechanical interference to the powder layer at the shallow part of the forming bin is small, the powder spreading speed can be greatly improved, and the efficiency is improved.

As shown in fig. 4:

fusion micro-comb powder spreading device: mainly comprises the following components: the powder falling assembly, the powder spreading assembly and the powder pressing roller. The structure and principle are basically the same as those described in fig. 1 and 2.

The guide rail (75) restricts the fusion micro-comb powder spreading device to move in 1 dimension, and the bracket (78) connects all the components together; a motor shaft (83) of a powder supply motor (73) drives a fusion powder supply roller (70) to rotate, a fusion groove (74) carries powder in a powder storage bin (71) to the bottom, powder is scraped out by a powder falling sheet (72) fixed by a fixing screw (80), and 1 powder falling sheet (72) is separated by a certain distance in particular for the purpose of clearing the internal structure; the 2 powder falling sheets correspond to 2 groups of fusion grooves; forming 1 fusion powder falling area (77) (4 fusion powder falling areas are shown in the figure, and more in practical application), leading out powder from a powder spreading funnel (79) by a powder storage funnel (85), and finally falling from a powder falling gap (84); there are 4 fused powder dropping areas in the figure. For clarity of internal structure, (82) is the hopper/cavity stripper portion and is separated by a distance.

The fusion powder falling area, namely the selective powder falling area, just falls on the area where the path travelled by the wedge-shaped front edge (59) of the powder scraping sheet is positioned at the central position of the front edge, and the micro-carding powder spreading process is carried out.

After the micro-carding and powder spreading process is completed, the powder layer is compacted by a powder pressing roller (76). Then the fusion micro-comb powder spreading device is moved out of the forming cylinder, the powder spreading layer is subjected to selective sintering or bonding treatment by utilizing laser sintering or glue spraying, and the process is repeated circularly until the process is completed; like fig. 1, the scraped excess powder can be recycled by a return bin for reuse. Other non-essential configurations are not relevant to the elucidation of the invention and are omitted here.

A residual powder channel (81) running along the translation direction is processed at the saw tooth root part of the saw tooth shape.

The fusion micro-comb powder spreading device works on the surface of the forming bin shown in fig. 3.

The present invention is not limited to the above-described preferred embodiments:

any person who is in the light of the present invention can obtain other products in various forms, however, any change in shape or structure is within the scope of the present invention, and all the technical solutions that are the same or similar to the present application are included.

Claims

1. The special fusion micro-comb powder spreading method for 3D printing of powder comprises the following steps: a powder falling process, a powder overflow removing micro-carding powder spreading process or a powder overflow reserving micro-carding powder spreading process are integrated; in the process of fusion powder falling, a powder supply motor drives a fusion powder supply roller to rotate and conveys stored powder in a powder storage bin to the bottom through a space formed by a fusion groove, the fusion groove is a closed space when contacting a powder falling sheet, and the self-thrust of the powder pushes the powder falling sheet away to fall; the method is characterized in that: the number of the powder falling sheets is as large as the number of the groove groups of the fusion grooves, the grooves of the same group are distributed on the same circumference, and the number of the grooves is 2 or more than 2; the other group is distributed on the other circumference, and the number of the grooves is 2 or more than 2; positional relationship of all grooves: seen along the axis direction of the fusion powder supply roller, 2 groups are sequentially overlapped end to end and are divided into an overlapped area and a single groove area; the cross section of the fusion groove is characterized in that the cross section of the groove is unchanged in a non-coincident region and the cross section is the same, the cross section gradually decreases until reaching zero in the coincident region, namely the depth of the groove gradually decreases to zero in the coincident region; the powder is discharged from the single groove and the single powder falling sheet in the non-overlapping area, and the powder is discharged from the double groove and the double powder falling sheet simultaneously in the overlapping area, wherein the quantity of discharged powder is equal to the sum of discharged powder from the double powder falling sheets; the process of removing the powder overflowed and micro-combing and paving the powder is a process of selectively or uniformly discharging the powder from a forming cylinder, then scraping the powder by using a comb-shaped powder scraping sheet which has a shovel-shaped appearance and is processed with a tooth-shaped front edge, and simultaneously sweeping the powder accumulated in a powder overflow area; the process of spreading the powder by the overflow-remaining micro-comb is a process of scraping the powder by using a comb-shaped powder scraping sheet which has a shovel-shaped appearance and is processed with a tooth-shaped front edge after selectively or uniformly falling the powder on a molding cylinder, or directly spreading the powder by using a straight scraping plate; after the powder spreading processes are finished, the laser sintering molding or the glue spraying and bonding molding process is carried out, and then the one-round molding process is finished; then the piston on the forming cylinder descends one layer of height again, and then the next round of forming process is carried out, and the cycle is repeated; the comb-shaped powder scraping sheet is of a shovel-shaped appearance structure, and the front edge part is processed into a thinner comb shape and is provided with a sawtooth shape; the tip part is thinner, the structure far away from the tip part is thicker, the contact line of the powder layer on the surface of the forming cylinder is a sawtooth-shaped curve, the sawtooth-shaped curve is a plane curve, the width of the curve is 1/10-100 mm, and the plane of the curve coincides with the surface of the forming bin opening; the comb-shaped powder scraping sheet slides on the surface of the molding bin opening, and the tips of the saw teeth just enable redundant powder to be separated towards the two sides of the tooth tips so as to fill a powder falling-free area of selective powder falling.

2. The method for paving the fusion micro-comb special for 3D printing of powder of claim 1, wherein the comb-shaped powder scraping sheet is structurally installed and used for vibrating a comb-shaped part at the front edge of the comb-shaped powder scraping sheet by using an oscillator.

3. The fusion micro-comb powder spreading method special for powder 3D printing of claim 1, wherein the uniform powder falling process is characterized in that: uniformly falling powder in the vertical direction of the comb-shaped powder scraping sheet, wherein the powder quantity falls once or repeatedly; in the process of uniform powder falling, the selective powder falling refers to a strip-shaped area of a tooth point running path of the front edge part of the comb-shaped powder scraping sheet, wherein the powder falling sheet is arranged in a mode that the powder falling width is smaller than the pitch of the tooth points of the front edge part of the comb-shaped powder scraping sheet, so that the powder falling area is necessarily present or not, a powder belt exceeding the layering thickness needs to be accumulated in the strip-shaped area, and no powder falling exists in an area outside the strip-shaped area of the tooth point running path of the front edge part of the comb-shaped powder scraping sheet.

4. The method for paving powder by using the fusion micro-comb specially for 3D printing of powder according to claim 1, wherein the root area of the serrated saw teeth suitable for shoveling powder is kept to be a smooth curved surface or is provided with a residual powder channel running along a translation direction, so that powder separated by a tooth tip and slipped and accumulated to the tooth root during shoveling is prevented from being excessively piled up and transferred along the residual powder channel, and the residual powder is actively removed at the end of paving powder.

5. The fusion micro-comb powder paving method special for powder 3D printing, which is characterized in that the process of sweeping the powder accumulated in the powder overflow area is as follows: powder in the powder overflow area (13) accumulated in the powder scraping process of the comb-shaped powder scraping sheet is timely moved out of the toothed area at the front end of the comb-shaped powder scraping sheet by a spiral brush or a powder suction device or a powder blowing device; the spiral brush has the structure that bristles root on a cylinder, the direction of the bristles points to the radial direction, and the whole cylinder is not fully covered with the bristles, but is spirally distributed or purely axially distributed on the cylinder; the powder suction device is structurally characterized in that a pipeline is used for sucking redundant powder; the structure of the powder blowing device is that the excess powder is blown out of the molding cylinder by using a pipeline or is spread on a large area of the surface of the molding cylinder which is not scraped.

6. The fusion micro-comb powder spreading method special for powder 3D printing according to claim 1, wherein the cross section of the groove is shaped as follows: the powder falling plate is in a trapezoid shape with a lower narrow upper wide shape or an arc shape with a lower narrow upper wide shape, and has self compensation function when being in sliding fit with a contact point of the lower narrow upper wide shape of the powder falling plate, and abrasion does not affect a fit clearance.