KR101894371B1 - Blade with multi-steps scrapper and powder feeding device blade using the blade - Google Patents

Abstract

Disclosed is a powder feeding device which comprises: a guide member in which raw material powder is fed to an upper surface; and a blade forming a powder layer by transferring the raw material powder supplied on the guide member. Moreover, the blade has a multi-step scraper coming in contact with the raw material powder to transfer the raw material powder.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a blade having a multistage scraper,

The present invention relates to a blade having a multistage scraper and a powder feeder using the multistage scraper, and more particularly, to a blade having a multistage scraper for conveying raw material powder in one direction so as to improve powder transfer and application characteristics, To a powder feeder.

The powder feeder is so-called "Powder Bed System ", which is a device for feeding powder at the beginning of the lamination process. Typical stacking processes using a powder feeder may include a selective laser sintering (SLS) process, a selective laser melting (SLM) process, and an electron beam melting (EBM) process. have.

The selective laser sintering process is an additive manufacturing process or a rapid prototyping process. The selective laser sintering process is repeatedly performed on a layer-by-layer basis using powders to manufacture parts having good mechanical properties. can do. Specifically, a raw material such as a metal powder mixture is transported in a thin layer of, for example, about 0.25 mm, and a laser beam is injected onto the surface of the powder according to the shape of the part to be manufactured so that the powder is mutually adhered. As a result, a two-dimensional solid pattern corresponding to the cross section of the part to be manufactured is formed. If the powder layer is repeatedly formed by repeating this process, a three-dimensional shaped component can be manufactured.

At this time, it is known that the mechanical properties of finished parts are largely influenced by the characteristics of the powder, the energy of the laser, and the means for supplying the powder. For example, the initial pores of the raw material powder may impair the mechanical properties of the product by leaving pores in the finished part, and a separate post-treatment process may be performed to control such pores.

Particularly, the feeding characteristics of the raw material powder largely depend on the design and configuration of the powder feeding means, and conventionally, as such powder feeding means, a rotating roller, a slot hopper, a scraper blade and the like have been employed.

A powder feeder employing the rotating roller is disclosed in U.S. Patent No. 5,155,324 (Deckard, et al., Issued to Deckard et al.). This document shows a reverse rotating roller which forms a target film by sweeping the raw material powder in units of layers.

Further, in the slot hopper method, the powder contained in the hopper is configured to be discharged and supplied through a slot formed at the lower end thereof.

On the other hand, referring to Fig. 1, in which the construction of the scraper blade is simply shown, the scraper blade is configured to feed and supply the powder 100 by the blade 1 in the form of a blade. When the scraper blade 1 transfers the powder 100, an initial frictional force is generated intensively between the end portion of the blade 1 and the powder. This is because the supply characteristic of the powder 100 (for example, The radius of curvature, the density of the powder (100) layer, the surface property of the powder (100) layer, and the like). Particularly, when the scraper blade 1 is in contact with the surface of the powder 100, fine scratches or marks may be left on the surface of the powder layer, which may adversely affect the mechanical properties of the finished product. Furthermore, these factors can be further exacerbated by the non-uniformity of the powder particles (i.e., the degree to which the powder deviates from the sphere or the agglomeration of the particles).

Due to such problems of the powder coating layer, the thickness, density, surface roughness and the like of the lamination portion are significantly different in the production process of the flux bed type melt laminate. Also, in the case of a single scraper, it is difficult to control the thickness, density, flatness, and amount of material used in the powder coating layer of the powder coating layer.

U.S. Patent No. 5,155,324: Method For Selective Laser Sintering With Layerwise Cross-scanning

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a blade having a multi-stage scraper in one direction which can improve the supply characteristic of the powder.

It is still another object of the present invention to provide a multi-stage scraper capable of dispersing an initial frictional force generated between a blade and a raw material powder, improving uniformity of a coating layer, precision in thickness and density, And to provide a powder feeder employing a blade.

In order to accomplish the above object, according to an embodiment of the present invention, a blade having a multi-stage scraper includes a multi-stage scraper, which is conveyed by the scraper located forward of the multi-stage scraper, A buffer space is formed in which a portion of the raw material powder can be stored, and the raw material powder stored in the buffer space can be transferred by the scrapers positioned at the rear.

According to an embodiment of the present invention, a height difference (H) is formed between a lower end of the scraper positioned at the front side and a lower end of the scraper positioned at the rear side, and a height difference between the upper side of the guide member and the lower end of the scraper The distance D1 may be set to be larger than the distance D2 between the upper surface of the guide member 30 and the lower end of the scraper located behind.

According to an embodiment of the present invention, the front inclination of the scraper positioned behind the front inclination of the scraper positioned at the front may be smaller.

According to an embodiment of the present invention, the entire surface of the scrapers may have a predetermined curvature.

According to another aspect of the present invention, there is provided a powder supply apparatus using a blade having a multistage scraper, including: a guide member to which raw material powder is supplied to an upper surface; And a blade having a multi-stage scraper in one direction so that the raw material powder supplied on the guide member is transferred in one direction to form a powder layer.

According to the blade having the multi-stage scraper of the present invention and the powder feeder using the same, the initial frictional force generated by contact with the raw material powder can be effectively dispersed by the multi-stage scrapers provided in the blade. As a result, the raw material powder can be spread evenly, so that the straightness of the powder is improved and a powder layer of uniform density can be obtained.

Advantages and advantages of the present invention will become more apparent from the following detailed description.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view illustrating a blade used in a conventional powder feeder. FIG.
FIG. 2 is a conceptual view schematically showing a configuration of a selective laser sintering system employing a powder feeder having a multi-stage scraper according to an embodiment of the present invention.
FIGS. 3 to 6 are schematic views showing the configuration of the blades of the powder supply device according to the embodiments of the present invention.
7 is a view showing the concept of the maximum width and the average curvature of the powder layer developed by the blade according to the experimental example of the present invention.
8 is a graph showing the feeding characteristics when powder is fed by the powder feeder according to the embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a blade having a multi-stage scraper according to a preferred embodiment of the present invention and its operation and operation will be described in detail with reference to the accompanying drawings. Prior to this, the expression "expanding the raw material powder " used in this specification should be understood to mean to spread the raw material powder by sweeping to the thickness of the powder layer. The "object product" refers to a product that is finally completed by a selective laser sintering process, which is an embodiment of the present invention. Further, in the drawings attached to the present specification, the same reference numerals denote the same components.

FIG. 2 is a conceptual diagram schematically showing a configuration of a selective laser sintering system employing a powder feeder using a blade having a multi-stage scraper according to an embodiment of the present invention.

Referring to FIG. 1, the selective laser sintering system includes a chamber 10 in which a selective laser sintering process is performed, and a powder layer 110 formed by a raw material powder 100 supplied into the chamber 10, And a high energy beam mechanism 20 for irradiating the beam. The high energy beam may be a laser beam or an electron beam.

The inside of the chamber 10 can be appropriately controlled depending on the kind of the raw powder 100 so that the powder layer 110 having suitable and good characteristics and the resulting product can be completed. More specifically, the temperature and humidity within the chamber 10 can be controlled and a gas such as, for example, an inert gas, may be selectively supplied to facilitate the selective laser sintering process.

The high energy beam mechanism 20 includes a high energy beam oscillator 21 for generating a high energy beam and a focusing unit 20 for focusing the beam generated from the high energy beam oscillator 21 to generate a high energy beam 22. [ (23). The high energy beam oscillator 21 may be composed of a conventional YAG laser or a CO ₂ laser well known in the art. The focusing unit 23 is supported on the XY table 24 and can be moved in accordance with coordinates by a separate driving means such as a motor 25 so that a high energy beam 22), that is, a laser beam can be irradiated. However, the configuration of such a high energy beam mechanism 20 is not limited by this embodiment, and various other types of laser generating and irradiating devices may be employed. For example, the focusing unit 23 may be replaced by a scanning mechanism including a prism (not shown) which refracts the input high energy beam 22.

In the selective laser sintering system, a powder feeder using a blade having a multi-stage scraper according to the present invention may be employed.

Specifically, the powder supply device includes a guide member 30 installed in the chamber 10, a lamination plate 31 provided so as to be able to move up and down on the guide member 30, and a raw material powder And a blade 40 having a multi-stage scraper for developing the powder layer 110. [

The laminating plate 31 is installed on the raw material powder receiving port 32 formed in the guide member 30 so as to be vertically movable by the conveying mechanism 33. At this time, the raw material powder 100 is supplied to the upper surface of the laminating plate 31 to form a powder layer 110. The powder layer 110 is irradiated and sintered by the laser beam 22, 200) can be produced three-dimensionally.

The blade 40 transports the raw powder 100 supplied into the chamber 10 and feeds and expands the raw powder 100 onto the lamination plate 31 to form the powder layer 110. Here, the "powder layer 110" means a unit layer of the powder 100 supplied onto the lamination plate 31 in the raw material powder receiving port 32, Forming a unit of a basic process for forming a red pattern. A plurality of such unit layers are laminated and the sintering process proceeds to form a three-dimensional target product 200.

Preferably, the guide member 30 is provided with a raw material powder feed port 34, and the raw material powder feed port 34 may be provided with a raw material feed and convey mechanism 35 capable of raising and lowering up and down. The raw material powder 100 is filled in the upper part of the raw material supply and conveying mechanism 35 and then the raw material supplying and conveying mechanism 35 is gradually raised to supply the raw material powder 100 into the chamber 10. The raw material powder 100 supplied by the raw material supply and conveying mechanism 35 is supplied to the raw material powder receiving port 32 by the blade 40 to form the powder layer 110.

According to the present invention, the blade (40) includes at least two scrapers (41a, 41b) whose cross section is in the form of a blade. The detailed structure and characteristic of such a blade 40 will be described later with reference to Figs. 3 to 6.

The selective laser sintering system configured according to one embodiment of the present invention may be connected to and controlled by a separate computer device 40 in a wired or wireless manner. Preferably, the computer apparatus is capable of, for example, having a CAD / CAM application program and associated data and controlling the two-dimensional coordinates that the high energy beam 22 irradiates. Such a configuration is a conventional technique well known in the art and will not be described in further detail.

3 is a view schematically showing an example of a blade 40 having a multi-stage scraper included in the powder supply apparatus according to the embodiment of the present invention. Here, FIG. 3 represents the shape of the side sectional view of the blade 40 as an example.

Referring to FIG. 3, the blade 40 provided in the powder supply device of the present invention includes at least two of the powder particles, which are arranged in one direction, so as to form a powder layer by transferring the raw powder supplied on the guide member 30 in one direction. The scaffers 41a and 41b are formed on the lower side. In the case of the blade 40 illustrated in FIG. 3, the first scraper 41a and the second scraper 41b are provided.

The scrapers 41a and 41b are brought into direct contact with the raw material powder 100 supplied into the chamber 10 by the raw material supply and conveying mechanism 35 and transferred to the raw material powder receiving port 32, 100) to develop a uniform powder layer 110. [0051] As shown in FIG.

For this purpose, it is preferable that the front surfaces of the scrapers 41a and 41b contacting the raw material powder 100 are formed to be inclined, and the inclination can be appropriately adjusted as needed.

According to the present invention, in at least two scrapers 41a and 41b, the lower end of the first scraper 41a located at the front is positioned higher than the lower end of the second scraper 41b located at the rear side thereof, A predetermined height difference H may be formed between the lower end of the first scraper 41a and the lower end of the second scraper 41b. More specifically, the distance D1 between the upper surface of the guide member 30 and the lower end of the first scraper 41a is smaller than the distance D2 between the upper surface of the guide member 30 and the lower end of the second scraper 41b ). Although in the present specification and the drawings, the distance D1 between the upper surface of the guide member 30 and the lower end of the first scraper 41a is shown and described as being spaced apart at considerable intervals, It should be understood that the distance D1 is set appropriately as a fine interval, for example, depending on the particle size of the powder to be supplied. 3, the lower end of the first scraper 41a and the lower end of the second scraper 41b may be formed to be parallel to the upper surface of the guide member 30. As shown in FIG.

When the blade 40 having the multi-stage scraper configured as described above pushes and feeds the raw material powder 100, the raw material powder 100 sequentially comes in contact with the first and second scrapers 41a and 41b, The frictional force can be dispersed in comparison with the conventional single scraper blade. Particularly, the first scrapers 41a, which are first in contact with the raw material powder 100, transport the powder 100 located in the upper layer portion, and then the second scrapers 41b, which follow it, 100), the friction force can be significantly dispersed and reduced compared to a conventional single scraper blade that is in direct contact with the entire powder heap.

According to the present invention, the distance between the first scraper 41a and the second scraper 41b is preferably set in the range of 1 mm to 5 mm, but is not particularly limited by such a range.

Further, the height difference (H) between the lower end of the first scraper 41a and the lower end of the second strapper 41b is also preferably set within a range of 0.1 mm to 0.5 mm. However, It is not. In another embodiment, the height difference H may be set to be equal to or greater than the thickness of the powder layer 110 formed on the lamination plate 31 by the raw material powder 100.

FIGS. 4 to 6 are views schematically showing still another example of the multi-stage scraper blade 40 provided in the powder supply apparatus according to the embodiment of the present invention.

The blade 401 shown in Fig. 4 has first and second scrapers 411a and 411b having different front inclination degrees. That is, the inclination of the front surface of the second scraper 411b located behind the front scraper 411a located at the front is smaller. In this case, the first scraper 411a may function to primarily transfer the dummy powder 100, and the second scraper 411b may function to develop the material powder 100 more precisely .

Referring to FIG. 5, the blade 402 according to the present embodiment includes a cushioning space SP of a predetermined size, which is closed between a first scraper 412a located at the front and a second scraper 412b located at the rear, . In this case, a part of the raw powder 100 to be primarily transported by the first scraper 412a enters the buffer space SP and is transported again by the second scrapers 412b, It is possible to further reduce the frictional force with the support member 100.

According to another embodiment of the present invention, the blade 403 having a multistage scraper shown in FIG. 6 has first and second scrapers 413a and 413b having a front surface formed with a predetermined curvature. With such a configuration, the frictional force with the raw material powder 100 can be continuously attenuated, so that the powder layer 110 having a more uniform thickness can be formed. Here, the front curvature radius of the first scraper 413a and the curvature radius of the second scraper 413b may be the same or different from each other and are not particularly limited by the present invention.

In the above embodiments, the blades having two scrapers are shown and the structure thereof is described, but the same configurations can be applied even when three or more scrapers are used. That is, a height difference (corresponding to H in FIG. 3) is formed stepwise between the lower ends of the scrapers. The lower end of the scrapers (for example, 41a) A height difference is formed so as to be farther away from the upper surface of the guide member 30 as compared with the lower end. Also, at least one buffer space may be provided between three or more scrapers, and the front inclination of the scrapers may also be set so as to gradually decrease toward the rear.

Further, while embodiments of the present invention illustrate blades with one multistage scraper, it should be understood that more than one multiple blades may be installed, depending on the system to which the powder feeder of the present invention is applied.

Hereinafter, the operation of the selective laser sintering system using the powder supplying apparatus according to the present invention will be described with reference to FIGS. 2 and 3. FIG.

First, the raw material powder 100 is supplied while the atmosphere in the chamber 10 is properly set. The raw material powder 100 may be appropriately selected according to the target product 200 and may be selected from the group consisting of iron or non-ferrous metal powder, polymer powder, ceramic powder or plastic powder (ABS, PVC, polycarbonate ), Etc., or a mixed powder thereof may be selected. The raw material powder 100 is filled in the raw material supply and conveying mechanism 35 and then supplied into the chamber 10 along the raw material powder feed port 34 as the raw material supply and conveyance mechanism 35 is lifted up. do. At this time, it is preferable that the amount of the raw material powder 100 to be supplied is set to be larger than the amount of the powder 100 that is supplied to the raw material powder receiving port 32 to form the powder layer 110.

Then, the blade 40 having the multi-stage scraper pushes the supplied raw material powder 100 and transfers it to the raw material storage port. At this time, a plurality of scrapers 41a and 41b provided on the blade 40 are sequentially contacted with the raw powder 100 as described above to disperse frictional force, and a uniform thickness And the powder layer 110 having a high density can be developed and formed.

Next, a high energy beam 22 is irradiated onto the upper surface of the powder layer 110 in accordance with a data signal transmitted from, for example, an externally installed computer device 50. At this time, the region irradiated with the high energy beam 22 corresponds to the sectional shape of the unit layer in the target product 200 to be finally produced. Next, the powder 100 is bound and sintered by the energy of the high energy beam 22 to form a two-dimensional pattern.

When the sintering of the powder layer 110 is completed as described above, the powder layer 110 corresponding to the next upper layer can be manufactured in the same manner. The feed mechanism 33 of the raw material powder receiving port 32 is also driven so that the laminating plate 31 is pressed against the surface of the unit powder layer 110 It is lowered by the thickness.

In this state, the supplied raw material powder 100 is transferred to the raw material powder receiving port 32 by the blade 40, and a new powder layer 110 is developed and formed on the lamination plate 31 accordingly. Next, by irradiating the high energy beam 22 in the same manner as above, the powder 100 particles of the new powder layer 110 are mutually bonded and sintered.

By repeating the above process, the desired product 200 is completed.

<Experimental Example>

The present inventor conducted an experiment for conveying a raw material powder in comparison with a conventional powder feeder employing a blade having a single scraper in order to confirm the feedability of the powder feeder using a blade having a multistage scraper according to the present invention, Were compared.

The cross-section of each of the scrapers of the conventional single-scraper blade and the multi-stage scraper of the present invention was formed in the same shape, and the powder was flat-expanded using the Fe-Cu mixed powder, Respectively. At this time, the amount of powder was 10 ml, and the blades according to the present invention were composed of two scrapers, and the gap between them was set to 3 mm. Also, experiments were performed by dividing the difference in height between the first scraper located at the front side and the second scraper located at the rear side by 0.1 mm, 0.2 mm, and 0.3 mm, respectively.

The maximum width and average curvature of the powder layer developed by each blade were measured in the above experiment. FIG. 7 shows the concept of these characteristics, and FIG. 8 is a bar graph showing the measurement result.

As shown in the figure, in the conventional single-scraper blade and the multi-stage scraper blade according to the present invention, the maximum width W of the powder layer was not different between the both. However, in the average curvature R, it can be seen that the average curvature of the powder layer by the multi-stage scraper according to the present invention is larger than the average curvature of the powder layer by the conventional single-scraper blade. This means that the straightness of the powder conveyed by the blades having the multi-stage scraper according to the present invention is better than that of the conventional ones, and also the powder straightness thus obtained can be formed in such a manner that the powder layer can be formed with a uniform thickness and density .

As described above, the blades having a multi-stage scraper according to the present invention and the powder feeder using the same can be manufactured by a selective laser sintering (SLS) process, a selective laser melting (SLM) process and an electron beam melting (EBM) Electron Beam Melting) process and so on, it is possible to guarantee excellent supply characteristic of powder.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. There may be even examples.

10: chamber 20: high energy beam mechanism
21: high energy beam oscillator 22: high energy beam
23: Focusing part 24: XY table
30: Guide member 31: Lamination plate
32: raw material powder receiving port 33: conveying mechanism
34: Feedstock for raw material powder 35: Feedstock feeding mechanism
40: blade 41: scraper
41a, 411a, 412a, 413a: a first scraper
41b, 411b, 412b, 413b: a second scraper
50: Computer device

Claims (5)

A blade having a multi-stage scraper in one direction so that a raw material powder supplied from a raw material powder feed port is transferred in one direction to form a powder layer,
A cushioning space is formed so as to be able to store a portion of the raw material powder conveyed by the scraper located at the front between the scraper located forward and the scraper located forwardly of the multi-stage scraper,
The raw material powder stored in the buffer space is conveyed by the scraper located at the rear,
A height difference (H) is formed between a lower end of the scraper located at the front side and a lower end of the scraper located at the rear side and a distance D1 between the upper surface of the guide member formed with the raw material powder feed port and the lower end of the scraper located forward Is set to be larger than a distance (D2) between an upper surface of the guide member and a lower end of the scraper located behind the guide member,
The lower end of the scraper positioned at the front side and the lower end of the scraper positioned at the rear side are formed in parallel to the upper surface of the guide member
Wherein the front surface of the scrapers is formed to have a predetermined curvature. delete The method according to claim 1,
Wherein a front inclination of the scraper located behind the front inclination of the scraper located in front of the blade is smaller than that of the blade. delete A blade having a multi-stage scraper in one direction so that a raw material powder supplied from a raw material powder feed port formed in a guide member installed in a chamber of a powder feeder can be transferred in one direction to form a powder layer,
The blade
A cushioning space is formed between the scraper located at the front and the scraper located at the rear of the multi-stage scraper so as to store a part of the raw material powder conveyed by the scraper located at the front,
The raw material powder stored in the buffer space is conveyed by the scraper located at the rear side
The lower end of the scraper positioned at the front side and the lower end of the scraper positioned at the rear side are formed in parallel to the upper surface of the guide member
Wherein the front surface of the scrapers is formed to have a predetermined curvature.

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