Directional powder spreading device for laser selective melting formingTechnical Field
The invention relates to the field of selective laser melting, in particular to a selective laser melting forming directional powder spreading device.
Background
The laser selective melting technology belongs to one of 3D printing technologies, is a revolutionary manufacturing technology developed in recent years, takes discrete-stacking as a basic principle, selectively melts metal powder through high-energy laser, and finally forms three-dimensional parts with small size and complex structure through layer-by-layer melting and stacking, and has the advantages of high forming speed, high forming freedom, single-piece small-batch production and the like, so that the laser selective melting technology has rapid application and development in the fields of aerospace, medical industry and the like.
However, when the conventional powder spreading mechanism spreads powder, a doctor blade having a length longer than the length of the substrate is generally used to spread the powder over the entire surface of the substrate. Because the laser selectively scans and melts the powder in the printing process, the powder in the space where the parts are not placed is not utilized, the traditional powder paving mode greatly increases the consumption of the powder, particularly expensive metal powder such as noble metal, superalloy and the like, and greatly increases the printing cost. And when the powder is cleaned after printing is finished, the excessive metal powder also increases the cleaning workload.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a laser selective melting forming directional powder spreading device, which is used for reducing the requirement and consumption of expensive metal powder and reducing the time cost of powder removal after printing.
The specific technical scheme is as follows:
The laser selective melting forming directional powder spreading device comprises a powder bin, a first moving mechanism, a second moving mechanism, a powder spreading scraper and a substrate, wherein the substrate is horizontally arranged at the bottom of a printing bin, the powder bin is arranged above the substrate and is used for containing powder for printing, the first moving mechanisms are horizontally arranged on two side walls of the printing bin which are arranged in parallel along a first direction respectively, the second moving mechanism is horizontally arranged between the two first moving mechanisms along a second direction, and horizontally moves along the first direction under the action of the first moving mechanism, and the first direction and the second direction are two orthogonal directions on a horizontal plane;
The powder spreading scraper is vertically arranged on the second moving mechanism and horizontally moves along the second direction under the action of the second moving mechanism, the size of a powder outlet of the powder bin is matched with the size of an upper port of the powder spreading scraper, when the powder bin is in butt joint with the powder spreading scraper, powder falls into the powder spreading scraper from the powder bin, and an annular adhesive tape is arranged at the bottom of the powder spreading scraper and used for scraping the powder.
The first moving mechanism comprises a first shell, a first motor, a first screw rod and a first connecting block, wherein the first shell is fixedly connected to the side wall of the printing bin, the axis of the first shell is parallel to a first direction, the first motor is fixedly connected to one axial end of the inside of the first shell, one end of the first screw rod is fixedly connected with an output shaft of the first motor in a coaxial mode, the other end of the first screw rod is rotatably connected with the other axial end of the first shell, the first screw rod can rotate around the axis of the first screw rod under the action of the first motor, a through hole is formed in the first connecting block, internal threads matched with the first screw rod are formed in the through hole, and the first connecting block is arranged on the first screw rod through the through hole.
Further, the first shell adopts 6063 aluminum alloy profile.
The second movement mechanism comprises a cross beam, a second shell, a second motor, a second screw rod and a second connecting block, wherein two ends of the cross beam are respectively arranged on the first movement mechanism and horizontally move along a first direction under the action of the first movement mechanism;
The second shell is fixedly connected to the cross beam, the axis of the second shell is parallel to the second direction, the second motor is fixedly connected to one axial end inside the second shell, one end of the second lead screw is fixedly connected with an output shaft of the second motor in a coaxial mode, the other end of the second lead screw is rotationally connected with the other axial end of the second shell, the second lead screw can rotate around the axis of the second lead screw under the action of the second motor, a through hole is formed in the second connecting block, an internal thread matched with the second lead screw is arranged in the through hole, and the second connecting block is arranged on the second lead screw through the through hole.
Furthermore, the cross beam and the second shell are made of 6063 aluminum alloy profiles.
Further, the powder bin is of a shell structure with a hollow inside, a powder inlet at the top of the powder bin is used for loading powder for printing, a powder outlet at the bottom of the powder bin is used for outputting the powder, a spring sliding cover is arranged at the powder outlet, the spring sliding cover is closed under the action of no external force, namely the powder outlet is closed, and when the powder laying scraper is in butt joint with the powder outlet of the powder bin, the spring sliding cover is opened.
Further, the powder spreading scraper is a hollow shell pipeline, the whole shell pipeline is in a form of being narrow at the upper part and wide at the lower part, the shell pipeline is divided into two sections, the upper half section is a rectangular pipeline, the lower half section is a prismatic table-shaped pipeline, and the bottom of the lower half section is rectangular.
Further, the powder bin, the powder spreading scraper and the substrate are all made of 316L stainless steel.
Further, a gap of 1mm is reserved between the bottom plane of the powder spreading scraper and the plane of the substrate, and a gap of 30 mu m is reserved between the lower end of the annular adhesive tape arranged at the bottom and the substrate.
The laser selective melting forming directional powder spreading method is realized according to the laser selective melting forming directional powder spreading device, and comprises the following steps:
S1, installing the laser selective melting forming directional powder spreading device in a printing bin according to requirements, and filling powder for printing in the powder bin;
s2, a control end sends out a signal to drive the motor I and the motor II to rotate positively or reversely, so that the powder spreading scraper moves to the lower end of the powder bin to receive powder;
S3, the control end drives the motor I and the motor II to rotate positively or reversely, so that the powder spreading scraper moves according to a set path, and powder falls onto the substrate through a channel in the powder spreading scraper and is spread by the annular adhesive tape;
s4, executing a subsequent laser sintering step;
s5, repeatedly executing S2-S4 until printing is completed.
The beneficial effects of the invention are as follows:
(1) The invention can avoid spreading powder on the whole substrate in the metal printing and powder spreading process, reduce the consumption of powder in the printing process, reduce the exploitation and processing of new metal raw materials, reduce the damage to the environment, meet the requirement of sustainable development, and particularly greatly reduce the cost of materials in the printing of noble metals.
(2) According to the invention, after the metal 3D printing is finished, the parts buried by the metal powder are cleaned from the powder bed, and because the cleaning process is carried out in a narrow isolation space through the glove window, the process is generally complicated, so that less powder is used in the printing process, the subsequent cleaning workload can be directly reduced, and the processing period is shortened.
Drawings
FIG. 1 is a schematic diagram of a laser selective melting forming directional powder spreading device in an embodiment of the invention.
Fig. 2 is a cross-sectional view of the powder cartridge structure in an embodiment of the invention.
Fig. 3 is a schematic structural view of a longitudinal movement mechanism in an embodiment of the present invention.
Fig. 4 is a schematic structural view of a lateral movement mechanism in an embodiment of the present invention.
Fig. 5 is a schematic diagram of connection between the second connection block and the scraper in the embodiment of the invention.
Fig. 6 is a cross-sectional view of a doctor blade configuration in an embodiment of the invention.
Fig. 7 is a schematic bottom view of a doctor blade structure in an embodiment of the invention.
In the figure, a powder bin 1, a first moving mechanism 2, a shell 1, a motor 2-2, a screw rod 2-3 and a connecting block 2-4, a second moving mechanism 3, a shell 2-1, a motor 3-2, a screw rod 3-3 and a connecting block 3-4, a powder spreading scraper 4, an annular adhesive tape 4-1 and a base plate 5.
Detailed Description
The objects and effects of the present invention will become more apparent from the following detailed description of the preferred embodiments and the accompanying drawings, in which the present invention is further described in detail. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in figure 1, the directional powder spreading device for laser selective melting forming comprises a powder bin 1, a first moving mechanism 2, a second moving mechanism 3, a powder spreading scraper 4 and a substrate 5. The base plate 5 is arranged horizontally at the bottom of the printing bin, and the powder bin 1 is arranged right above the base plate 5, and the powder falling port of the powder bin is vertically downward. The vertical direction is taken as the z direction, a pair of vertical and parallel wall surfaces of the printing bin are taken as side walls, the normal direction of the side walls is the y direction, the other pair of vertical and parallel wall surfaces are taken as front walls and rear walls, the normal direction of the front walls and the rear walls is the x direction, the x direction and the y direction are mutually perpendicular and are positioned on the same plane, and the x direction is also the conventional moving direction of a scraper of the existing powder paving device. The two side walls of the printing bin are respectively and horizontally provided with a first moving mechanism 2 along a first direction (namely, the x direction in fig. 1), a second moving mechanism 3 is horizontally arranged between the two first moving mechanisms 2 along a second direction (namely, the y direction in fig. 1), and two ends of the second moving mechanism 3 are respectively arranged on the two first moving mechanisms 2 and can horizontally move along the first direction under the action of the first moving mechanisms 2. The powder spreading scraper 4 is vertically arranged on the second movement mechanism 3 and can horizontally move along the second direction under the action of the second movement mechanism 3. Preferably, the powder bin 1, the powder spreading scraper 4 and the substrate 5 are all made of 316L stainless steel.
As shown in fig. 2, the powder bin 1 is a hollow shell structure, the powder for printing can enter the powder bin 1 from the powder inlet at the top and fall out from the powder outlet at the bottom, the spring sliding cover is arranged at the powder outlet, and the spring sliding cover is closed without any external force, so that the powder cannot fall out through the powder outlet. The size of the powder outlet of the powder bin 1 is matched with the size of the upper port of the powder spreading scraper 4, the powder spreading scraper 4 pushes the spring sliding cover in the process of abutting joint between the lower part of the powder bin 1 and the powder outlet, powder falling from the powder bin 1 can completely enter the powder spreading scraper 4 to realize the receiving of the powder, and when the powder spreading scraper 4 moves away, the spring sliding cover is closed again under the action of the spring.
Preferably, the lower end of the powder bin 1 is provided with a structure bent towards the first direction, and the design ensures that when the powder bin 1 is closely attached to the front wall or the rear wall of the printing bin, the powder spreading scraper 4 cannot collide with the front wall or the rear wall, and on the other hand, the bent structure slows down the falling speed of powder, so that the powder can be better received.
As shown in FIG. 3, the first movement mechanism 2 comprises a shell I2-1, a motor I2-2, a screw rod I2-3 and a connecting block I2-4. The shell I2-1 is a 6063 aluminum alloy profile, is fixedly connected to the side wall of the printing bin and has an axis parallel to the x direction, and is internally provided with a motor screw structure consisting of a motor I2-2 and a screw I2-3, wherein the motor screw structure is formed by the motor I2-2 and the screw I2-3, and the shell I2-1 plays a role in protection. In the motor screw structure, a motor I2-2 is fixedly connected to one axial end of a shell I2-1, one end of a screw I2-3 is coaxially and fixedly connected with an output shaft of the motor I2-2, and the other end of the screw I2-3 is rotationally connected with the other axial end of the shell I2-1, so that the screw I2-3 can rotate around the axis of the motor I2-2 under the action of the motor I2-2. The first connecting block 2-4 comprises a connecting platform and a protruding structure on the connecting platform, a through hole is formed in the protruding structure, an internal thread matched with the first lead screw 2-3 is arranged in the through hole, the first connecting block 2-4 is arranged on the first lead screw 2-3 through the through hole, when the first lead screw 2-3 rotates, the first connecting block 2-4 can horizontally move along the x direction, and at the moment, the first lead screw 2-3 plays a role of a guide rail.
As shown in FIG. 4, the second movement mechanism 3 comprises a cross beam, a second shell 3-1, a second motor 3-2, a second screw rod 3-3 and a second connecting block 3-4. The two ends of the cross beam are respectively and fixedly connected to the connecting platforms of the first connecting block 2-4, the cross beam and the second shell 3-1 are also made of 6063 aluminum alloy profiles, the second shell 3-1 is fixedly connected to the cross beam, a motor screw rod structure is arranged in the second shell, and the second shell 3-1 plays a role in protection. In the motor screw structure, a motor II 3-2 is fixedly connected to one axial end of a housing II 3-1, one end of a screw II 3-3 is coaxially and fixedly connected with an output shaft of the motor II 3-2, and the other end of the screw II 3-3 is rotationally connected with the other axial end of the housing II 3-1, so that the screw II 3-3 can rotate around the axis of the motor II 3-2. And a through hole is formed in the second connecting block 3-4, an internal thread matched with the second screw rod 3-3 is formed in the through hole, the second connecting block 3-4 is arranged on the second screw rod 3-3 through the through hole, and when the second screw rod 3-3 rotates, the second connecting block 3-4 can horizontally move along the y direction.
The longitudinal movement mechanism 2 is matched with the transverse movement mechanism 3, and the corresponding connecting blocks are moved on the corresponding screw rods through forward rotation and reverse rotation of the motor I2-2 and the motor II 3-2, so that the powder spreading scraper 4 is driven to realize self-defined movement in the x direction and the y direction.
As shown in fig. 5, the powder spreading scraper 4 is fixedly connected with the second connecting block 3-4. As shown in fig. 6, the powder spreading scraper 4 is a shell pipeline, the shell pipeline is divided into two sections, the upper half section is a rectangular pipeline, the lower half section is a prismatic table-shaped pipeline, the bottom is rectangular, and the whole powder spreading scraper 4 is in a form of being narrow at the upper part and wide at the lower part. As shown in fig. 7, the bottom of the powder spreading scraper 4 is provided with a notch-shaped groove, and an annular adhesive tape 4-1 is arranged in the groove and used for scraping the powder. In the embodiment, a gap of 1mm is formed between the bottom plane of the powder spreading scraper 4 and the plane of the substrate 5, a gap of 30 μm is formed between the lower end of the annular adhesive tape 4-1 and the substrate 5 after the annular adhesive tape 4-1 is arranged, and in the powder spreading process, the powder can be scraped when the powder spreading scraper 4 spreads powder in the x direction and the y direction, and a metal powder layer with the thickness of 30 μm is spread.
According to the above-mentioned laser selective fusion forming directional powder spreading device, the embodiment also provides a laser selective fusion forming directional powder spreading method, which specifically comprises the following steps:
S1, installing the laser selective melting forming directional powder spreading device in a printing bin according to requirements, and filling powder for printing in the powder bin 1.
And S2, the control end sends out a signal to drive the motor I2-2 and the motor II 3-2 to rotate positively or reversely, so that the powder spreading scraper 4 moves to the lower end of the powder bin 1 to receive powder.
And S3, driving the motor I2-2 and the motor II 3-2 to rotate positively or reversely by the control end so that the powder spreading scraper 4 moves according to a set path, and the powder falls onto the substrate 5 through a channel in the powder spreading scraper 4 and is spread by the annular adhesive tape.
And S4, executing the subsequent laser sintering step.
S5, repeatedly executing S2-S4 until printing is completed.
It will be appreciated by persons skilled in the art that the foregoing description is a preferred embodiment of the invention, and is not intended to limit the invention, but rather to limit the invention to the specific embodiments described, and that modifications may be made to the technical solutions described in the foregoing embodiments, or equivalents may be substituted for elements thereof, for the purposes of those skilled in the art. Modifications, equivalents, and alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.