CN112873834A

CN112873834A - Additive manufacturing equipment and control method thereof

Info

Publication number: CN112873834A
Application number: CN202110070294.5A
Authority: CN
Inventors: 曾思齐; 司妞; 梁冬生; 林江波; 黄鸿喜
Original assignee: Hunan Farsoon High Tech Co Ltd
Current assignee: Hunan Farsoon High Tech Co Ltd
Priority date: 2021-01-19
Filing date: 2021-01-19
Publication date: 2021-06-01
Anticipated expiration: 2041-01-19
Also published as: CN112873834B

Abstract

An additive manufacturing device and a control method thereof are disclosed, wherein the device comprises a working platform, N printing mechanisms and a base pillar, wherein the N printing mechanisms are sequentially arranged around the base pillar at intervals and form relative rotation with the base pillar, and the distances from the printing mechanisms to the center of the base pillar are in an arithmetic progression; the printing mechanism comprises a powder storage box, a scanning system and a scraper mechanism, wherein the lower end of the powder storage box is provided with a powder discharging roller, powder in the powder storage box is charged or magnetized to generate electric charge or magnetism opposite to the electric charge or magnetism on the base pillar, the powder is controlled to fall from at least one side of the powder storage box, the falling powder is adsorbed on the surface of the base pillar or a sintered powder layer on the surface of the base pillar, the scraper mechanism is used for scraping the powder adsorbed on the surface of the base pillar or the sintered powder layer on the surface of the base pillar, and the scanning system is used for scanning and sintering the scraped powder. The additive manufacturing equipment and the control method thereof not only improve the printing efficiency, but also ensure the printing quality of the workpiece.

Description

Additive manufacturing equipment and control method thereof

Technical Field

The application relates to the technical field of additive manufacturing, in particular to additive manufacturing equipment and a control method thereof.

Background

The additive manufacturing technology is an advanced manufacturing technology with the distinct characteristics of digital manufacturing, high flexibility and adaptability, direct CAD model driving, high speed, rich and various material types and the like, and has a very wide application range because the additive manufacturing technology is not limited by the complexity of the shape of a part and does not need any tool die. The Selective Laser Melting (SLM) is one of the rapidly developed additive manufacturing technologies in recent years, and it uses powder material as raw material, and adopts Laser to scan the cross section of three-dimensional entity layer by layer to complete prototype manufacturing, and is not limited by the complexity of part shape, and does not need any tooling die, and its application range is wide. The basic process of the selective laser melting process is as follows: the powder feeding device feeds a certain amount of powder to the surface of the working platform, the powder paving device flatly paves a layer of powder material on the bottom plate of the forming cylinder or the upper surface of the formed part, and the laser galvanometer system controls laser to scan the powder layer of the solid part according to the cross section outline of the layer with approximately unchanged spot size and beam energy, so that the powder is melted and bonded with the formed part below; after the section of one layer is sintered, the working platform is lowered by the thickness of one layer, the powder spreading device is used for spreading a layer of uniform and compact powder on the working platform, the section of a new layer is scanned and sintered, and the whole prototype is manufactured through scanning and stacking of a plurality of layers.

Although the application range of the additive manufacturing equipment is more and more extensive at present, the quality of printed products is also continuously improved. However, in the field of additive technology, further improvement of printing efficiency and printing quality is still an ongoing goal and difficulty.

Disclosure of Invention

In view of the above, it is necessary to provide an additive manufacturing apparatus and a control method thereof that improve printing efficiency and printing quality in view of the above technical problems.

In order to achieve the purpose, the invention provides additive manufacturing equipment which comprises a working platform, N printing mechanisms and a cylindrical base pillar with charges or magnetism, wherein the N printing mechanisms and the cylindrical base pillar are arranged on the working platform, the N printing mechanisms are sequentially arranged around the base pillar at intervals and form relative rotation motion with the base pillar, the distance between each printing mechanism and the center of the base pillar is in an arithmetic progression, the tolerance is the layer thickness, and N is an integer greater than or equal to 2; wherein the content of the first and second substances,

the printing mechanism comprises a powder storage box, a scanning system and a scraper mechanism located between the powder storage box and the scanning system, wherein a powder discharging roller is arranged at the lower end of the powder storage box and used for charging or applying magnetism to powder in the powder storage box to generate electric charge or magnetism opposite to the electric charge or magnetism on a base column and controlling the powder to fall from at least one side of the powder storage box, so that the falling powder is adsorbed on the surface of the base column or a sintered powder layer located on the surface of the base column, the scraper mechanism is used for scraping the powder adsorbed on the surface of the base column or the sintered powder layer located on the surface of the base column, and the scanning system is used for scanning and sintering the scraped powder.

Preferably, the N printing mechanisms are fixedly arranged on the working platform, and the base columns are arranged on the working platform and rotate according to a preset direction.

As a further preferable aspect of the present invention, N is 3, and the adjacent printing mechanisms form a first line segment and a second line segment with the center of the pillar, respectively, and an included angle between the first line segment and the second line segment is an angle a.

As a further preferable scheme of the present invention, a powder returning chamber is provided between the scraper mechanism and the powder storage box, and a bottom surface of the powder returning chamber is lower than a bottom surface of the scraper mechanism for recovering excess powder scraped by the scraper mechanism.

As a further preferable aspect of the present invention, the powder returning chamber is connected to a powder recovering system, and the powder recovering system generates a negative pressure so that the inert gas recovers the excess powder.

As a further preferable aspect of the present invention, the scanning system is disposed in the first cavity, and at least one side of the first cavity is provided with a cavity communicated with the first cavity, for recovering smoke generated by scanning and sintering performed by the scanning system.

As a further preferable scheme of the invention, one side of the first cavity, which is close to the powder storage box, is provided with a second cavity, the other side of the first cavity is provided with a third cavity, the bottom of the third cavity is provided with a milling cutter used for removing burrs generated on a sintering surface, and the third cavity is used for recovering chips generated in the working process of the milling cutter.

As a further preferred aspect of the present invention, the second cavity and the third cavity are respectively connected to a gas circulation system, so that the gas circulation system sucks away smoke and/or debris.

In a further preferred embodiment of the present invention, the pillar has a hollow structure.

Based on the same inventive concept, the present invention also provides a control method of the additive manufacturing apparatus described in any one of the above, including the steps of:

the method comprises the following steps that firstly, N printing mechanisms and a base pillar are driven to form relative rotation movement, and the base pillar is charged;

secondly, respectively controlling the powder in the powder storage boxes of the N printing mechanisms to fall after being filled with charges with the polarity opposite to that of the charges on the base pillar by the powder discharging roller so as to enable the charged powder to be adsorbed on the surface of the base pillar or the sintered powder layer on the surface of the base pillar;

thirdly, respectively controlling scraper mechanisms of the N printing mechanisms to scrape powder adsorbed on the surface of the base pillar or the sintered powder layer on the surface of the base pillar;

step four, respectively controlling scanning systems of the N printing mechanisms to scan and sinter the scraped powder so as to finish the printing of the current N layers;

moving the N printing mechanisms respectively by N layer thicknesses along respective radial directions far away from the center of the base pillar;

and step six, returning to execute the step two until the process is finished after the workpiece is printed.

By adopting the technical scheme, the additive manufacturing equipment and the control method thereof have the following beneficial effects:

1. the printing speed is high, and multi-layer printing of one working cycle can be realized by setting the number of printing mechanisms.

2. The printing method is particularly suitable for printing large annular workpieces, and the printed annular workpieces are printed from inside to outside of the circumference, so that the internal stress is balanced, the workpieces are not easy to curl and crack due to the internal stress, and the printing quality of the workpieces is better ensured.

3. Because the printing sequence of the workpieces is that the workpieces are printed from inside to outside from the circumference, the method conforms to the rule of the optimal mechanical strength of radial growth of blade workpieces such as airplane turbines.

Drawings

FIG. 1 is a schematic diagram of an additive manufacturing apparatus according to an embodiment;

FIG. 2 is a top view of FIG. 1;

FIG. 3 is an enlarged view of a portion of FIG. 2;

FIG. 4 is a schematic diagram of a first process state provided by the additive manufacturing apparatus in one embodiment;

FIG. 5 is a schematic diagram of a second process state provided by the additive manufacturing apparatus in one embodiment;

FIG. 6 is a schematic diagram of a third process state provided by the additive manufacturing apparatus in one embodiment;

FIG. 7 is a schematic diagram of a fourth process state provided by the additive manufacturing apparatus in one embodiment;

FIG. 8 is a schematic diagram of a fifth process state provided by the additive manufacturing apparatus in one embodiment;

fig. 9 is a schematic diagram of a sixth process state provided by the additive manufacturing apparatus in an embodiment.

In the figure: 1. printing mechanism, 10, motion track, 2, work platform, 3, pillar, 11, powder storage box, 12, scanning system, 13, scraper mechanism, 111, powder, 112, burr, 121, powder feeding roller, 14, powder returning cavity, 15, first cavity, 16, second cavity, 17, third cavity, 18, milling cutter, 19, powder recycling system, 20, gas circulation system, three-layer powder (01, 02, 03), 101, first printing mechanism, 102, second printing mechanism, 103 and third printing mechanism.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

As shown in fig. 1 to 3, the present invention provides an additive manufacturing apparatus, including a working platform 2, N printing mechanisms 1 disposed on the working platform 2, and a cylindrical base pillar 3 with charges or magnetism, where the N printing mechanisms 1 are sequentially disposed at intervals around the base pillar 3 and form a relative rotation motion with the base pillar 3, distances from centers of the base pillars 3 to the printing mechanisms 1 are in an arithmetic progression, a tolerance is a layer thickness, and N is an integer greater than or equal to 2; wherein the content of the first and second substances,

the printing mechanism 1 comprises a powder storage box 11, a scanning system 12 and a scraper mechanism 13 positioned between the powder storage box 11 and the scanning system 12, wherein the lower end of the powder storage box 11 is provided with a powder discharging roller 121 for charging or applying magnetism to the powder 111 in the powder storage box 11 to generate electric charge or magnetism with polarity opposite to that of the electric charge or magnetism on the base pillar 3 and controlling the powder 111 to fall from at least one side of the powder storage box so that the falling powder 111 is adsorbed on the surface of the base pillar 3 or a sintered powder layer on the surface of the base pillar 3, the scraper mechanism 13 is used for scraping and leveling the powder surface of the powder 111 adsorbed on the surface of the base pillar 3 or the sintered powder layer on the surface of the base pillar 3, and the scanning system 12 is used for scanning and sintering the scraped powder 111.

In one embodiment, as shown in fig. 3, the powder discharge roller 121 is connected to a high voltage negative electrode to make the powder 111 negatively charged after falling; the pillars 3 are connected to the positive electrode, so that the powder 111 can be adsorbed on the pillars 3 or the sintered powder layer on the surface of the pillars 3 by positive and negative attraction, and the particles of the powder 111 are negatively repelled from each other, and the adsorbed surface is uniform, such as three layers of powder (01, 02, 03) in fig. 2. It is of course also possible to apply magnetism to the powder 111 and the pillars 3. In addition, the powder dropping roller 121 is installed vertically to the horizontal plane and is driven to rotate counterclockwise by a driving mechanism to drop the powder 111 in the powder storage box 11 from one side or both sides (the powder 111 is dropped from only one time in fig. 3, which facilitates to reduce the space occupied by the apparatus).

It should be noted that fig. 1 to 3 illustrate three printing mechanisms 1, i.e., N is 3, but in the implementation, N may be 2, 4, 5, etc. according to the design requirement, which is not illustrated herein.

Preferably, for convenience of arrangement, 3 printing mechanisms 1 are fixedly arranged on the working platform 2, the base pillar 3 is arranged on the working platform 2 and rotates in a preset direction, for example, in a clockwise direction, at this time, the 3 printing mechanisms 1 respectively comprise a first printing mechanism 101, a second printing mechanism 102 and a third printing mechanism 103 which are arranged from inside to outside and in a clockwise direction, that is, the first printing mechanism is closest to the center of the base pillar 3, and the third printing mechanism 103 is farthest from the center of the base pillar 3. The adjacent printing mechanisms 1 respectively form a first line segment and a second line segment with the circle center of the base column 3, and the included angle between the first line segment and the second line segment is an angle a.

Preferably, a powder returning cavity 14, which may be an elongated cavity, is provided between the scraper mechanism 13 and the powder storage box 11, and a bottom surface of the powder returning cavity 14 is lower than a bottom surface of the scraper mechanism 13 for recovering the excess powder 111 scraped by the scraper mechanism 13. The powder return chamber 14 is also connected to a powder recovery system 19, said powder recovery system 19 generating a negative pressure to allow the inert gas to recover the excess powder 111.

As shown in fig. 2 and 3, the scanning system 12 is disposed in the first cavity 15, and a cavity communicated with the first cavity 15 is disposed on at least one side of the first cavity 15, for recovering smoke generated by scanning and sintering performed by the scanning system 12. Specifically, the scanning system 12 may be a scanning head of various modes, and the scanning head is preferably composed of a fiber laser, a single-axis galvanometer and a field lens, and has a low cost and a simple principle. Fiber laser does not draw, and the unipolar shakes the mirror axis of rotation and 3 pivot spaces of pillar are perpendicular, and the section is preferred to be formed by a strip and the parallel line segment of 3 axes of rotation of pillar, and laser passes through the unipolar and shakes the mirror swing, and the field lens guarantees that the light spot is unanimous in the scanning area, and preferred light spot is unanimous, and 3 clockwise rotations of rotatory pillar, the scanning head scans every route planned in proper order, like this, after 3 rotatory a week of pillar, the sintering has also been accomplished on the present layer.

Further preferably, a second cavity 16 is arranged on one side of the first cavity 15 close to the powder storage box 11, a third cavity 17 is arranged on the other side of the first cavity, a milling cutter 18 for removing burrs 112 generated on the sintering surface is arranged at the bottom of the third cavity 17, the milling cutter 18 can be in a roller shape and is driven by a driving mechanism to perform rotary motion so as to remove the burrs 112 generated on the sintering surface; the third cavity 17 is used for recovering chips generated by the milling cutter 18 in the working process, and the surface milled by the milling cutter 18 is smooth, so that conditions are created for laying powder on the next layer. Preferably, the bottom surface of the milling cutter 18 is slightly lower than the bottom surface of the scraper mechanism 13, for example, the distance from the bottom of the milling cutter 18 to the center of the base cylinder 3 is smaller than the distance from the bottom of the scraper mechanism 13 to the center of the base cylinder 3 by 0.05mm, so that the milling cutter 18 can remove the burr 112 generated on the sintering surface without affecting the sintered powder layer.

The second cavity 16 and the third cavity 17 are tightly attached to the first cavity 15, and the second cavity 16 and the third cavity 17 are connected to the first cavity 15 through two absorption windows, respectively, and the second cavity 16 and the third cavity 17 are further connected to the gas circulation system 20, respectively, so that the gas circulation system 20 sucks away the smoke and/or debris to ensure the cleanliness of the sintering process powder 111.

The additive manufacturing equipment is particularly suitable for large annular workpieces, and of course, solid workpieces can be printed, so that the selected base column material is consistent with the powder material, and after printing is finished, the base column part is used as one part of the workpiece, and only the redundant base column part is cut off.

In specific implementation, the base pillar 3 may be a solid or hollow structure, preferably a hollow structure, so that when the size of the annular workpiece is too large, the hollow structure can save the cost of the base barrel, wherein the specific size of the base pillar 3 needs to be selected according to the size of the workpiece to be printed.

It should be noted that the powder storage box 11, the powder returning cavity 14 and the scraper mechanism 13 may be spliced, and of course, the powder storage box 11 and the powder returning cavity 14 may be integrally arranged; the first, second and

third cavities

15, 16, 17 may be integrally or jointly arranged.

Based on the same inventive concept, the present invention also provides a control method of the additive manufacturing apparatus according to any one of the above embodiments, including the steps of:

the method comprises the following steps that firstly, N printing mechanisms 1 and a base column 3 are driven to form relative rotation movement, and meanwhile, the base column 3 is charged;

secondly, respectively controlling the powder 111 in the powder storage boxes 11 of the N printing mechanisms 1 to fall after being charged with charges with the polarity opposite to that of the charges on the base pillars 3 by the powder discharge roller 121, so that the charged powder 111 is adsorbed on the surfaces of the base pillars 3 or the sintered powder layers on the surfaces of the base pillars 3;

step three, respectively controlling scraper mechanisms 13 of the N printing mechanisms 1 to scrape the powder 111 which is adsorbed on the surface of the base column 3 or the sintered powder layer on the surface of the base column 3;

step four, respectively controlling the scanning systems 12 of the N printing mechanisms 1 to scan and sinter the scraped powder 111 to complete the printing of the current N layers;

step five, moving the N printing mechanisms 1 by N layer thicknesses along respective radial directions far away from the circle center of the base column 3;

It should be noted that the technical scheme of the invention is mainly suitable for printing annular workpieces, especially large annular workpieces, and can greatly improve the printing efficiency.

For the purpose of promoting an understanding of and enabling persons skilled in the art to practice the subject invention, reference will now be made in detail to the accompanying drawings.

Fig. 4 to 9 mainly illustrate the printing process of one-step forming and three-layer scanning of the three printing mechanisms 1.

As shown in fig. 4, a circle represents the pillar 3 or a powder package having completed n scanning cycles, and as described below with reference to the pillar 3, a small rectangle represents three printing mechanisms 1 (as shown in fig. 4, the first printing mechanism 101, the second printing mechanism 102, and the third printing mechanism 103, respectively), three scanning heads are distributed on three moving tracks 10 radially radiating from the rotation center of the pillar 3, and the closest points of the first printing mechanism 101, the second printing mechanism 102, and the third printing mechanism 103 are respectively at the closest distances n, 2n, 3n, and n are scanning layer thicknesses (after passing through the milling cutter 18) to the pillar 3 in a clockwise number, and the moving tracks 10 of adjacent printing mechanisms 1 are separated by an angle a.

Preferably, a scanning head space is provided for the cutter retraction of the following printing mechanism 1, interference between the scanning head and a layer is prevented when a certain layer is stacked, the second printing mechanism 102 performs delayed scanning relative to the first printing mechanism 101, the third printing mechanism 103 performs delayed scanning relative to the second printing mechanism 102, that is, when the base column 3 rotates a + b (b is smaller than a) degrees, the first printing mechanism finishes the scanning layer thickness corresponding to a + b, and the second printing mechanism 102 starts scanning, so that b degrees are added. That is, the angles of the start points of the first layer, the second layer and the second layer are different by a, and the angles of the real-time scanning positions of the first layer, the second layer and the second layer are different by b. It should be noted that the specific delay time of adjacent printing mechanisms, i.e. the specific value of the b angle, can be specifically set according to the needs, and is not limited in the present invention.

As shown in FIG. 5, when the pillars 3 continue to rotate to 2a +2b degrees, the first layer has scanned a circle corresponding to 2a +2b degrees, the second layer has scanned a circle corresponding to a + b degrees, and the third layer starts scanning.

As shown in fig. 6, the pillar 3 is rotated to 180+ c degrees (i.e. the rotation angle of the pillar 3 is greater than 180 degrees), the first layer has scanned a circumference of 180+ c degrees, the first layer is about to close, and it can be seen that the second layer and the third layer have a step-like arc length corresponding to each short b angle in the previous layer.

As shown in fig. 7, the base pillar 3 rotates 360 degrees, and due to the angle difference b between the second layer and the first layer, the first printing mechanism 101 does not interfere with the second layer, and the first layer finishes scanning and closing, at this time, the first printing mechanism 101 stops scanning, and immediately moves 3n along the moving track 10 away from the rotation center of the base pillar 3 to prepare for the next scanning period.

As shown in fig. 8, the base pillar 3 continues to rotate to 360+ a + b degrees, the scanning head does not interfere with the third layer due to the angular difference b existing between the third layer and the second layer, the second layer completes scanning closure, at this time, the second printing mechanism 102 stops scanning, and immediately moves 3n along the moving track 10 away from the rotation center of the base pillar 3 to prepare for the next scanning period.

As shown in fig. 9, the base pillar 3 continues to rotate to 360+2a +2b, the third layer finishes scanning and closes, and the third printing mechanism 103 stops scanning and moves 3n along the moving track 10 away from the rotation center of the base pillar 3 to prepare for the next scanning period.

The timing for completing three-level scanning for one scanning cycle is described above, and the following scanning cycles in the same manner.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The additive manufacturing equipment is characterized by comprising a working platform, N printing mechanisms and a cylindrical base pillar with charges or magnetism, wherein the N printing mechanisms and the cylindrical base pillar are arranged on the working platform, the N printing mechanisms are sequentially arranged around the base pillar at intervals and form relative rotation with the base pillar, the distance between each printing mechanism and the center of the base pillar is in an arithmetic progression, the tolerance is the layer thickness, and N is an integer greater than or equal to 2; wherein the content of the first and second substances,

2. The additive manufacturing apparatus according to claim 1, wherein the N printing mechanisms are fixedly disposed on a working platform, and the pillars are disposed on the working platform and rotate in a preset direction.

3. The additive manufacturing apparatus of claim 1, wherein N is 3, and the adjacent printing mechanisms form a first line segment and a second line segment with the center of the base pillar, respectively, and the included angle between the first line segment and the second line segment is an angle a.

4. Additive manufacturing device according to claim 1, wherein a powder return chamber is provided between the scraper mechanism and the powder storage tank, and a bottom surface of the powder return chamber is lower than a bottom surface of the scraper mechanism for recovering excess powder scraped by the scraper mechanism.

5. Additive manufacturing apparatus according to claim 4 wherein the powder recovery chamber is connected to a powder recovery system that generates a negative pressure to allow the inert gas to recover excess powder.

6. Additive manufacturing device according to claim 1, wherein the scanning system is arranged in the first cavity, and a cavity communicating with the first cavity is arranged on at least one side of the first cavity for recovering fumes generated by scanning and sintering performed by the scanning system.

7. Additive manufacturing device according to claim 6, wherein the first cavity is provided with a second cavity on one side close to the powder storage tank and a third cavity on the other side, the bottom of the third cavity is provided with a milling cutter for removing burrs generated on the sintering surface, and the third cavity is used for recovering chips generated during the operation of the milling cutter.

8. Additive manufacturing apparatus according to claim 7, wherein the second and third cavities are each connected to a gas circulation system for the gas circulation system to suck away smoke and/or debris.

9. Additive manufacturing apparatus according to any one of claims 1 to 8, wherein the base pillar is a hollow structure.

10. A method of controlling an additive manufacturing apparatus according to any one of claims 1 to 9, comprising the steps of: