CN116213756A

CN116213756A - Method and device for paving powder in flexible area of selective laser melting

Info

Publication number: CN116213756A
Application number: CN202310002717.9A
Authority: CN
Inventors: 邢一思; 李怀学; 胡全栋; 徐�明
Original assignee: AVIC Beijing Aeronautical Manufacturing Technology Research Institute
Current assignee: AVIC Beijing Aeronautical Manufacturing Technology Research Institute
Priority date: 2023-01-03
Filing date: 2023-01-03
Publication date: 2023-06-06

Abstract

The invention relates to a method and a device for paving powder in a flexible area of selective laser melting, wherein a forming substrate is selected according to the size of a part, and the forming substrate is divided into a powder falling area and a powder paving area; selecting a powder feeding roller according to the size of the powder falling area; moving the powder storage box filled with powder to the position right above the powder falling area; setting a starting point and a finishing point of powder spreading movement of a powder spreading baffle according to the size of a forming substrate, wherein the starting point and the finishing point of the powder spreading movement of the powder spreading baffle are the positions of the outer edge of a powder falling area; placing the powder feeding roller at an initial position, setting the rotation number of the powder feeding roller, and performing a single powder spreading experiment; observing whether continuous superfluous powder exists outside the edge of the powder spreading area, if so, recording the rotation number of the powder feeding roller, taking the rotation number as a powder feeding quantity parameter, otherwise, increasing the rotation number of the powder feeding roller until continuous superfluous powder exists outside the edge of the powder spreading area; the purpose is to effectively reduce the powder consumption in the molding process.

Description

Method and device for paving powder in flexible area of selective laser melting

Technical Field

The invention belongs to the field of powder bed additive manufacturing, and particularly relates to a method and a device for paving powder in a flexible area by using laser selective melting.

Background

With the rapid development of the manufacturing technology of aerospace weaponry in China, a large number of key structures adopt complex cavity components, the manufacturing period is long, the finished product rate of products is low when the traditional technology is used for processing, and furthermore, certain complex structures cannot be developed, so that the requirements on the structure, performance and function of an aircraft cannot be met.

The laser selective melting is an advanced manufacturing technology for forming solid parts by data-driven and layer-by-layer accumulated materials, and compared with the traditional subtractive manufacturing, the technology can form a light-weight, complex structure and multi-material gradient structure, has short process flow and less material waste, does not need a die, supports personalized and customized processing, and is widely applied to the fields of aerospace, biomedical treatment, automobiles and the like. The technology is a complex process of mutually coupling various physical fields and highly dynamic by utilizing laser to scan powder which is laid in a forming area in advance and enabling the powder to be fused and deposited.

The powder spreading is the basis of laser scanning melting powder, and the powder spreading refers to spreading a layer of thin powder on a base plate of a forming cylinder, and an energy source can perform specific area melting forming on the powder layer according to the slice pattern of the part. The powder conveying of the selective melting forming equipment mainly comprises a lower powder supply mode and an upper powder falling mode. Both methods are to deliver powder to one end of a molded substrate and then push the powder to the entire substrate plane by a doctor blade.

At present, the whole forming substrate is fully paved in two ways, and the powder paving area range cannot be adjusted in real time according to the size of the forming part. When a large-format forming system forms small-size parts, powder is only required to be fused and formed in a local area in the format, but the current powder spreading device can only spread powder on the whole format, so that the powder demand is far greater than the actual part demand. Taking a large-format molding platform with a molding area of 1200mm and 1200mm as an example, for example, a full-format molding chamber needs to be paved with powder, and when the molding height is 1200mm, the height Wen Jinfen is about 7 tons. Therefore, the current powder spreading system can cause unnecessary increase of powder demand when a large-format platform forms small-size parts, and limits the application range of equipment.

Disclosure of Invention

The invention mainly aims at the problems and provides a method and a device for paving powder in a flexible area by using laser selective melting, which aim to effectively reduce the powder consumption in the forming process.

In order to achieve the above purpose, the invention provides a method for paving powder in a flexible area by selective laser melting, which comprises the following steps:

selecting a forming substrate according to the size of a part, and dividing a powder falling area and a powder spreading area on the forming substrate;

selecting a powder feeding roller with a powder outlet equal to or larger than the powder falling area in the length direction or in the width direction according to the size of the powder falling area;

moving the powder storage box filled with powder to the position right above the powder falling area;

setting a starting point and a finishing point of powder spreading movement of a powder spreading baffle according to the size of the forming substrate, wherein the starting point and the finishing point of the powder spreading movement of the powder spreading baffle are the positions of the outer edge of the powder falling area;

setting the rotation number of the powder feeding roller, and performing a single powder spreading experiment;

and observing whether continuous redundant powder exists outside the edge of the powder spreading area, if so, recording the rotation number of the powder feeding roller, taking the rotation number as a powder feeding quantity parameter, otherwise, increasing the rotation number of the powder feeding roller until continuous redundant powder exists outside the edge of the powder spreading area.

Further, when the initial rotation number of the powder feeding roller is set, if the initial powder spreading experiment is performed, continuous redundant powder is observed outside the edge of the powder spreading area, and whether the initial rotation number is reduced is judged according to the quantity of the continuous redundant powder.

Further, the powder feeding roller needs to return to the initial position of the powder feeding roller after completing the set rotation number each time.

Further, recording the real-time height of the forming substrate, judging the position of a powder spreading baffle, and calculating the height of the forming substrate to be lifted and the height of the forming substrate to be lowered corresponding to the powder spreading baffle; and controlling the corresponding forming substrate to ascend or descend according to the calculated height.

Further, the method for setting the rotation number of the powder feeding roller comprises the following steps:

calculating the powder spreading quantity matched with the size of the powder spreading area according to the size of the powder spreading area;

searching a powder feeding roller for releasing the powder spreading quantity within a certain rotation circle range according to the powder spreading quantity, wherein the powder feeding roller is a powder outlet which is equal to or larger than the length or width of the powder falling area in the length direction;

and setting the rotation number of the powder feeding roller in the obtained rotation number range, and taking the rotation number of the powder feeding roller as the rotation number of the powder feeding roller for paving powder in the forming processing.

In order to achieve the above purpose, the invention provides a laser selective melting flexible region powder spreading device, which comprises:

the powder storage box is provided with a cavity for storing metal powder to be processed and a discharge hole for delivering the metal powder to be processed in the cavity;

the powder feeding roller is detachably arranged on the discharge hole, and a powder feeding component with adjustable length is arranged on the powder feeding roller;

the driving component is connected with the powder feeding roller and is used for driving the powder feeding roller to rotate so as to control the powder discharge amount of the powder storage box;

and the powder spreading baffle is used for spreading the powder falling from the powder outlet from one end to the other end in the area.

Further, the powder feeding roller comprises a roller central shaft, powder blocking soft sleeves arranged at two ends of the roller central shaft and a powder discharging component arranged between the two powder blocking soft sleeves.

Further, the powder discharging component comprises a plurality of powder feeding clapboards arranged on the central shaft wall of the roller, wherein the area between two adjacent powder feeding clapboards is the powder discharging opening.

Further, the powder paving device also comprises a first motion transmission mechanism for driving the powder storage box to move and a second motion transmission mechanism for driving the powder paving baffle to move.

Further, the powder feeding partition boards are four groups, and every two adjacent powder feeding partition boards are vertically arranged at 90 degrees.

The technical scheme of the invention has the following advantages:

1. by flexibly adjusting the powder falling range and the moving area of the powder spreading mechanism, powder spreading in any local area in the formed breadth is realized;

2. the powder demand of large-format laser selective melting in forming small-size parts can be effectively reduced by flexibly paving powder in a local area, the substrate loss can be effectively reduced by adopting a small-size substrate, the processing cost is reduced, and the application range of equipment is expanded;

3. the powder spreading quantity required by the determination of the size of the powder spreading area can be calibrated by the rotation number of the powder feeding roller, so that the quantitative powder feeding of any area is realized.

Drawings

Fig. 1 is a schematic diagram of a structure for dividing a powder spreading area and a powder dropping area according to an embodiment of the present invention.

FIG. 2 is a flow chart of a method for paving powder in a laser selective melting flexible area according to an embodiment of the invention.

Fig. 3 is a schematic structural diagram of a laser selective melting flexible region powder spreading device according to an embodiment of the present invention.

Fig. 4 is a schematic perspective view of a powder feeding roller according to an embodiment of the present invention.

Fig. 5 is a schematic side view of a powder feeding roller according to an embodiment of the present invention.

Fig. 6 is a schematic structural diagram of a method for paving powder in a laser selective melting flexible area according to an embodiment of the invention.

Detailed Description

The following describes in further detail the embodiments of the present invention with reference to the drawings and examples. The following examples are illustrative of the invention and are not intended to limit the scope of the invention.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

The invention provides a method for paving powder in a flexible area by melting in a laser selective area, which comprises the following steps:

selecting a forming substrate 2 according to the size of a part, and dividing the forming substrate 2 into a powder falling area and a powder spreading area;

selecting a powder feeding roller 5 with a powder outlet in the length direction equal to or larger than the powder falling area in the length direction or the width direction according to the size of the powder falling area;

moving the powder storage box 4 filled with powder to the position right above the powder falling area;

setting a starting point and a finishing point of powder spreading movement of a powder spreading baffle plate 3 according to the size of the forming substrate 2, wherein the starting point and the finishing point of the powder spreading movement of the powder spreading baffle plate 3 are the positions of the outer edge of the powder falling area;

placing a powder feeding baffle plate 52 of the powder feeding roller 5 at an initial position, setting the rotation number of the powder feeding roller 5, and performing a single powder spreading experiment;

and observing whether continuous superfluous powder exists outside the edge of the powder spreading area, if so, recording the rotation number of the powder feeding roller 5, taking the rotation number as a powder feeding quantity parameter, otherwise, increasing the rotation number of the powder feeding roller 5 until continuous superfluous powder exists outside the edge of the powder spreading area.

In the above-described embodiments, the flexible region powder spreading method according to the present invention mainly relates to how to adjust the positioning of the powder storage tank 4 in the X direction, the powder falling width of the powder storage tank 4 in the y direction, the limitation of the movement region of the powder spreading baffle 3, the setting of the powder feeding amount, and the like in the case where the powder spreading regions are different. The relevant adjusting method is characterized in the following.

In the present embodiment, for a large-format forming stage, a forming substrate 2 of an arbitrary size smaller than a forming format may be mounted, and the forming substrate 2 is divided into two parts of a powder spreading area and a powder dropping area. The powder spreading area is a part forming area melted by the laser selective area. The powder storage box 4 is provided with a discharge hole which is positioned right above the powder falling area, powder is conveyed into the powder falling area, and the powder spreading baffle 3 starts to perform powder spreading movement from the end head of the powder falling area, so that the powder is spread and conveyed into the powder spreading area. Referring to fig. 1 in detail, a forming substrate 2 with a proper size is arranged on a laser selective melting forming platform 1 according to the size of a part to be formed, and the forming substrate 2 is divided into a powder falling area and a powder spreading area. The area marked by the rectangular frame ABEF is a powder falling area, and the area marked by the rectangular frame CDEF is a powder spreading area.

The powder spreading baffle 3 needs to set the start point and the end point of the powder spreading movement of the powder spreading baffle 3 according to the size of the molding substrate 2. As shown in fig. 1, the start position of the powder spreading is the coordinate position of the outer edge of the powder falling area along the straight line AB in the X-axis direction. The end position is a coordinate position of the outer edge of the molding region CDEF in the X-axis direction along the straight line CD.

The powder storage box 4 can do linear motion along the X-axis direction, the position of the powder storage box 4 is set according to different powder spreading areas, and the powder storage box 4 is not moved in the forming process after being positioned. According to fig. 4, the pre-molding powder bin 4 needs to be positioned directly above the powder drop zone ABEF to ensure that the powder delivered by the discharge port can fall within the powder drop zone.

The powder falling width of the powder storage box 4 needs to be adjusted according to the size of the powder spreading area in the y-axis direction. The powder falling width is mainly adjusted by means of a powder feeding roller 5 arranged at the discharge hole of the powder storage box 4. The powder feeding roller 5 is composed of a roller central shaft 50, a powder blocking soft sleeve 51 and a powder feeding baffle plate 52. The overall length of the powder feeding roller is fixed, the longer the powder blocking soft sleeve 51 is in the direction of the central axis of the roller, the shorter the length of the powder feeding partition plate 52 is, and the shorter the powder feeding width through the powder feeding partition plate 52 is, namely the smaller the powder falling width is. In practical application, powder feeding rollers 5 with different specifications are arranged according to different powder falling width requirements. When selecting the powder feeding roller 5, the length of the powder feeding partition plate 52 of the powder feeding roller 5 is required to be equal to or slightly larger than the length of the powder falling area in the y direction, so as to ensure that the powder falling width of the powder storage box 4 completely covers the effective powder falling area, and it should be noted that the length of the powder feeding partition plate 52 is required to be equal to or slightly larger than the length of the powder falling area in the y direction, or the length of the powder outlet of the powder feeding roller 5 is also required to be equal to or slightly larger than the length of the powder falling area in the y direction.

In order to avoid powder waste as much as possible, the powder feeding amount in each powder spreading period needs to be measured in advance according to the size of a powder spreading area and the thickness requirement of a powder spreading layer. The amount of powder feeding is determined by the number of rotations of the powder feeding roller 5. When a single-layer powder spreading amount measurement experiment is carried out, powder spreading experiments are carried out on a plurality of times of different powder feeding amounts, when continuous redundant powder exists outside the edge of a powder spreading area CD (see figure 1), the fact that the powder spreading area is full of powder and a small number of redundant powder falls is indicated, and the rotation number of the powder feeding roller 5 is recorded to serve as a powder feeding amount parameter. It should be noted that, each time the powder feeding roller 5 completes a set number of rotations, the roller returns to the initial position. And finally, forming the part by laser selective melting. The molding process is shown in fig. 2.

It should be noted that when the initial number of rotations of the powder feeding roller 5 is set, if the continuous surplus powder is observed outside the edge of the powder spreading area in the initial powder spreading test, it is necessary to determine whether to reduce the initial number of rotations according to the amount of the continuous surplus powder, so as to avoid serious waste.

In addition, the method for setting the rotation number of the powder feeding roller 5 comprises the following steps: according to the size of the powder spreading area, the powder spreading amount which is matched with the size of the powder spreading area is calculated, for example, the size of the powder spreading area is 50X50mm, the thickness of the powder spreading layer is required to be 40 psi m each time, the volume can be calculated, the quantity of powder falling into the powder falling area for a single time is approximately obtained according to the volume, the powder feeding roller with the powder opening length equal to or larger than the width is found according to the width of the powder spreading area, the approximate range of the rotation number is obtained according to experience or experimental parameters, the rotation number of the powder feeding roller 5 is set in the approximate range, and the probability that the powder output requirement is exactly met when the powder spreading measurement experiment is carried out for the first time is improved.

According to the embodiment, the method can determine the required powder spreading amount according to the size of the powder spreading area, and the powder feeding amount is calibrated through the rotation number of the powder feeding roller, so that quantitative powder feeding of any area is realized. Meanwhile, the powder demand of large-format laser selective melting in forming small-size parts can be effectively reduced by flexibly paving the powder in a local area, the substrate loss can be effectively reduced by adopting a small-size substrate, the processing cost is reduced, and the application range of equipment is expanded.

The invention also provides a laser selective melting flexible region powder spreading device, which is provided with a movable and positionable powder storage box 4, a flexible and detachable powder feeding roller 5 and a powder spreading baffle plate 3 which can be positioned at will. By adjusting the powder falling position of the powder storage box 4, the powder spreading area of the powder spreading baffle plate 3 and the powder feeding amount of the powder feeding roller 5, powder spreading of any local area in the formed breadth is realized.

The whole structure of the laser selective melting flexible region powder paving device is shown in fig. 3, and the specific characteristics are as follows:

the powder spreading device comprises a forming bin 6 and a system core control unit 9, wherein the forming bin 6 is of a square sealing structure, and a powder storage box 4, a powder feeding roller 5, a driving part (not shown), a powder spreading baffle 3, a first motion transmission mechanism 7 and a second motion transmission mechanism 8 are arranged in the forming bin 6.

The powder storage box 4 is provided with a cavity for storing metal powder to be processed and a discharge hole for delivering the metal powder to be processed in the cavity; the powder feeding roller 5 is arranged on the discharge hole in a detachable mounting structure, and the powder discharge hole is arranged on the powder feeding roller 5, and the detachable mounting structure is in threaded connection, buckle connection and hinge connection; the driving component is connected with the powder feeding roller 5 and is used for driving the powder feeding roller 5 to rotate so as to control the powder outlet of the powder storage box 4, and the powder outlet can be understood to be used for controlling the powder outlet; wherein, the powder spreading baffle 3 is used for spreading the powder falling from the powder outlet from one end to the other end in the area; the first motion transmission mechanism 7 is used for driving the powder storage box 4 to move, and the powder storage box 4 can realize linear motion and positioning by means of the first motion transmission mechanism 7; the second motion transmission mechanism 8 is used for driving the powder spreading baffle plate 3 to move, and the powder spreading baffle plate 3 can realize linear motion and positioning by means of the second motion transmission mechanism 8. The system core control unit 9 is used for controlling the linear motion of the powder storage box 4 and the powder spreading baffle 3 and controlling the rotation of the powder feeding roller 5.

The composition and connection relationship of the powder feeding roller 5 will be described in detail with reference to specific examples. The detailed structure of the powder feeding roller 5 is shown in fig. 4.

The powder feeding roller 5 is installed at the discharge hole of the powder storage tank 4, and a stepping motor (i.e. the driving component) is installed at one end of the powder feeding roller 5 and drives the powder feeding roller 5 to rotate. The powder feeding roller 5 is composed of a roller central shaft 50, a powder blocking soft sleeve 51 and a powder feeding partition plate 52 and is used for controlling the powder discharging amount of the powder storage box 4 and the powder falling width in the y-axis direction. The powder feeding roller 5 is a detachable part, and the powder feeding rollers 5 with different specifications can be replaced according to different powder laying areas. The method is characterized by comprising the following steps of:

the powder feeding roller 5 is driven by a stepping motor to rotate around the axis of the roller central shaft 50; the powder blocking soft sleeve 51 is a cylindrical soft sleeve made of a silica gel material, and the powder blocking soft sleeve 51 is arranged at two ends of the roller central shaft 50 and is distributed in a symmetrical mode. The outer surface of the powder blocking soft sleeve 51 is overlapped with the discharge port of the powder storage box 4 and rotates along with the roller central shaft 50. The powder blocking soft sleeve 51 is soft and elastic, and can be tightly attached to the side wall of the discharge hole of the powder storage box 4 and can freely rotate, so that the powder above the powder blocking soft sleeve 51 is prevented from falling. The powder feeding partition plate 52 is formed by splicing and fixing 4 stainless steel partition plates forming 90 degrees with each other, the edges of the powder feeding partition plate 52 are attached to the side wall of the discharge hole of the powder storage box 4 and can rotate along with the roller central shaft 50, and the top view of the placing position of the powder feeding partition plate 52 is shown in fig. 5. The discharge hole is divided into four parts by the four partition boards, and powder is accumulated in the space between the adjacent partition boards.

Setting the initial position of the powder feeding roller. As shown in fig. 5, when the horizontal center line L of the powder feeding roller 5 is parallel to the molding substrate 2, it is defined as the initial position of the powder feeding roller 5. The powder feeding roller 5 completely seals the discharge hole, and no powder falls down at the moment. When the powder feeding roller 5 rotates around the roller center shaft 50, the powder feeding baffle plate 52 continuously conveys the powder in the powder storage tank 4 onto the forming substrate 2. The longer the powder feeding roller 5 rotates, the more powder is fed.

The embodiment designs a flexible powder spreading device capable of flexibly adjusting the powder falling range, and the device comprises a powder storage box 4 capable of performing positioning movement, a powder spreading baffle plate 3 and a powder feeding roller 5 capable of controlling the powder falling width and the powder feeding amount. The device adopts the mode of falling powder on the upper surface, and the powder laying in any local area in the formed breadth is realized by flexibly adjusting the powder falling range and the moving area of the powder laying mechanism.

The technical solution of the present disclosure will be described below with a specific embodiment disclosed in the present application.

The laser selective melting apparatus selected in the examples had a formed web of 1200mm x 1200mm and a height of 1000mm. The width of the discharge hole of the powder storage box 4 is 1200mm. The roller center shaft 50 of the powder feeding roller 5 is 1200mm long. The part size to be processed is 260mm 280mm, and the part height is 160mm. The size of the selected forming substrate 2 is 350mm, and the forming substrate 2 is arranged at the center of the laser selective melting forming platform 1. The center of the laser selective melting forming platform 1 is set as the coordinate origin of the motion system. The X-axis direction is the powder spreading direction.

Step one: the powder fall region and the powder spread region are determined as shown in fig. 6. Wherein the powder falling area is a rectangular area with 350mm and 50mm. Rectangular area with powder spreading area 350 mm.300mm. The thickness of the powder is 40 μm.

Step two: powder dispensing roller 5 is selected. The length of the powder falling area in the y-axis direction is 350mm, so that the length of the powder feeding partition plate 52 of the powder feeding roller 5 is more than 350mm, the length of the powder feeding partition plate 52 selected in the embodiment is 400mm, and the lengths of the powder blocking hoses 51 at the two ends are 400mm respectively.

Step three: the powder storage tank 4 is filled with powder and moved to just above the powder falling area, and at this time, the coordinate of the powder storage tank 4 in the X direction is-150 mm.

Step four: the start point of the powder spreading movement of the powder spreading baffle plate 52 is set to be the position of the outer edge of the powder falling area, and the X-direction coordinate is-175 mm. The end point of the powder laying movement of the powder laying baffle plate 52 is set to be the position of the outer edge of the powder laying area, and the X-direction coordinate is 175mm.

Step five: powder feeding quantity measurement experiment. The powder feeding roller 5 is placed at the initial position. Setting different rotation numbers of the powder feeding roller 5, carrying out a single powder spreading experiment, and recording the rotation number of the powder feeding roller 5 as 12 circles when continuous redundant powder exists at the outer edge of a powder spreading area.

Step six: according to the measured data, the parameters related to powder laying and other process parameters are set in the core control unit.

Step seven: the powder feeding roller 5 rotates, and the Chu Fen bin starts to fall powder. The powder feeding roller 5 returns to the initial position after 12 turns, and the powder storage bin stops powder falling.

Step eight: the powder spreading baffle 3 performs powder spreading movement in the X-axis direction, and moves from the X coordinate to 175mm.

Step nine: the powder is laser melted.

Step ten: the forming cylinder was lowered by 40 μm.

Step eleven: the powder spreading baffle 3 returns to the X coordinate-175 mm.

Step twelve: and step six, re-executing, and entering the next processing period.

In summary, the powder spreading device adopts a mode of 'falling powder upwards', and realizes the function of locally spreading powder in any area in a formed breadth by a powder conveying system capable of being positioned at will, thereby solving the problem that the powder demand is overlarge when a large-breadth forming system forms small-size parts, and expanding the application range of large-breadth laser selective melting equipment. On the other hand, the large-format forming substrate often weighs hundreds of jin, and the installation and the movement before and after the forming are carried out need to be aided by a crane and other auxiliary tools, if the proper substrate can be selected according to the size of the part, the lifting of the substrate is convenient, and the waste of substrate materials after the linear cutting of the large substrate and the small part is avoided.

The foregoing is merely a preferred embodiment of the present invention, and it should be noted that it will be apparent to those skilled in the art that modifications and variations can be made without departing from the technical principles of the present invention, and these modifications and variations should also be regarded as the scope of the invention.

Claims

1. The method for paving the powder in the flexible area by using the laser selective melting is characterized by comprising the following steps of:

2. The method for paving powder in a flexible area by selective laser melting according to claim 1, wherein when an initial rotation number of the powder feeding roller is set, if a preliminary powder paving experiment is performed, a continuous superfluous powder is observed outside the edge of the powder paving area, and whether to reduce the initial rotation number is judged according to the quantity of the continuous superfluous powder.

3. The method for laying powder in a flexible area by selective laser melting according to claim 1, wherein said powder feeding roller is required to return to an initial position of said powder feeding roller after each completion of a set number of rotations.

4. The method for paving the powder in the flexible area by using the laser selective melting method according to claim 1, wherein the real-time height of the forming substrate is recorded, the position of a powder paving baffle is judged, and the height of the forming substrate to be lifted and the height of the forming substrate to be lowered corresponding to the powder paving baffle are calculated; and controlling the corresponding forming substrate to ascend or descend according to the calculated height.

5. The method for laying powder in a flexible area by selective laser melting according to claim 1, wherein the method for setting the rotation number of the powder feeding roller comprises the following steps:

6. A laser selective melting flexible region powder spreading device, characterized in that the powder spreading device comprises:

7. The laser selective melting flexible area powder spreading device according to claim 6, wherein the powder feeding roller comprises a roller central shaft, powder blocking soft sleeves arranged at two ends of the roller central shaft, and a powder discharging component arranged between the two powder blocking soft sleeves.

8. The laser selective melting flexible area powder spreading device according to claim 7, wherein the powder discharging component comprises a plurality of powder feeding clapboards arranged on the wall of the central shaft of the roller, wherein the area between two adjacent powder feeding clapboards is the powder discharging opening.

9. A laser selective melting flexible area powder spreading device as set forth in claim 6, further comprising a first motion transmission mechanism for driving the powder storage tank to move and a second motion transmission mechanism for driving the powder spreading baffle to move.

10. The laser selective melting flexible area powder spreading device according to claim 8, wherein the four groups of powder feeding clapboards are arranged vertically at 90 degrees between two adjacent powder feeding clapboards.