KR102428015B1 - Apparatus and method for mixing raw material of selective laser sintering 3D printing - Google Patents

Abstract

The present invention relates to an apparatus and method for mixing raw materials of SLS type 3D printer. The apparatus comprises: a used powder drum for storing used powder remaining after use in product molding; a new powder drum for storing fresh powder; a mixing powder drum for receiving and mixing the used powder of the used powder drum and the new powder of the new powder drum; a weight measuring means for measuring the weight of each of the used powder drum, the new powder drum, and the mixed powder drum; and a conveying and mixing means for conveying and mixing the powder stored inside the used powder drum, the new powder drum, and the mixed powder drum by using compressed air according to a measurement result of the weight measuring means. The present invention can measure the amount of used powder and new powder and automatically supply and mix the same at a certain ratio.

Description

Apparatus and method for mixing raw material of selective laser sintering 3D printing

The present invention relates to an SLS type 3D printer, and more particularly, to a raw material mixing apparatus and method for an SLS type 3D printer capable of mixing new powder and used powder in a predetermined ratio.

A 3D printer is a manufacturing device that outputs successive layers of material like a two-dimensional printer and laminates them to make an object, and is mainly used for prototype sample production, etc. because it can quickly produce an object based on digitized drawing information.

The product molding method of this 3D printer includes the SLA (Stereo Lithography Apparatus) method, which injects a laser into the photocurable resin so that the injected part is cured, the SLS (Selective Laser Sintering) method, which sinters using a functional polymer or metal powder, FDM (Fused Deposition Modeling) method that extrudes molten resin and molds it, DMT (Laser-aid Direct Metal Tooling) method that directly forms metal with a high-power laser beam, LOM (Laminated Object Manufacturing) method, which is a mechanical bonding molding method, photocurability There is a DLP (Digital Light Processing) method in which the resin is cured by irradiating light to the lower part of the water tank.

Among these 3D printers, the SLS (Selective Laser Sintering) type 3D printer, which forms 3D products by sintering functional polymer or metal powder, mixes new powder and used powder with raw material powder in a certain ratio. use.

Specifically, the operation of mixing new powder and used powder in the conventional 3D printer of the SLS method is as follows. First, the raw material, ie, the powder, in the build cylinder that has been molded is separated from the molded object, and the remaining powder is made into used powder. Then, after measuring the weight of the used powder, the total weight of the raw material is adjusted to the set weight by manually supplying the new powder to the raw material drum at a ratio determined according to the measured value. Then, the used powder in the raw material drum and the new powder are mixed using a raw material mixing device.

But. According to the raw material mixing method of the conventional SLS-type 3D printer, the user had to remember the weight of the used powder and manually supply the new powder to the raw material drum according to the set ratio. In addition, a human error occurred in the process of manually supplying the new powder to the raw material drum, making it difficult to manage the ratio of the used powder to the new powder, and there was a problem that the user had to always stand by the printer during this mixing process. Moreover, since a separate mixing device for mixing the raw materials must be provided in the 3D printer, there is a problem in that noise and heat are generated and power consumption is increased.

Prior Art Document 1: Korean Patent Registration No. 10-2002003 (2019.07.22. Announcement)

Prior Art Document 2: Korean Patent Registration No. 10-1886537 (2018.08.07. Announcement)

The present invention was invented to solve the above problems, and it provides a raw material mixing apparatus and method for an SLS type 3D printer capable of measuring the amount of used powder and new powder and automatically supplying and mixing them at a certain ratio. aim to

Another object of the present invention is to provide a raw material mixing apparatus and method for an SLS 3D printer capable of reducing noise and heat generated in the process of supplying and mixing raw materials and reducing power consumption.

In order to achieve the above object, the raw material mixing apparatus of the SLS type 3D printer according to the present invention includes: a used powder drum for storing used powder remaining after being used for product modeling; new powder drum for storing fresh powder; a mixing powder drum for receiving and mixing the used powder of the used powder drum and the new powder of the new powder drum; weight measuring means for measuring the weight of each of the used powder drum, the new powder drum, and the mixing powder drum; and a conveying and mixing unit for conveying and mixing the powder stored in the used powder drum, the new powder drum, and the mixing powder drum using compressed air according to the measurement result of the weight measuring unit.

Preferably, the weight measuring means includes a first load cell for measuring the weight of the used powder drum, a second load cell for measuring the weight of the new powder drum, and a third load cell for measuring the weight of the mixed powder drum a first vacuum ejector for transferring the used powder stored in the used powder drum to the mixing powder drum, and a load cell, wherein the transferring and mixing means transfers the new powder stored in the new powder drum to the mixed powder drum a second vacuum ejector, and a third vacuum ejector for mixing the used powder and the new powder stored in the mixing powder drum.

More preferably, the method further includes compressed air supply means for supplying compressed air to the first vacuum ejector, the second vacuum ejector, and the third vacuum ejector, wherein the compressed air supply means includes: an air compressor; a filter installed on a downstream side of the air compressor to remove impurities and moisture in the compressed air generated from the air compressor; a regulator installed on the downstream side of the filter and adjusting the pressure of the compressed air that has passed through the filter; It is installed on the downstream side of the regulator and is turned on so that compressed air positively pressured by the regulator is supplied to at least one of the first vacuum ejector, the second vacuum ejector, and the third vacuum ejector, or inside the compressed air supply means The start valve is turned OFF so that the compressed air remaining in the exhaust is discharged to the outside; And it is installed on the downstream side of the start valve, the first vacuum ejector, the second vacuum ejector, and the third vacuum ejector by controlling the ON/OFF of the three flow paths respectively connected to the compressed air to the vacuum ejector It includes a solenoid valve to allow supply.

Here, each of the first vacuum ejector, the second vacuum ejector, and the third vacuum ejector includes: a main body formed in a cylindrical pipe shape and having a straight flow path through which compressed air flows in one direction; a compressed air inlet formed in an annular or spiral shape along the periphery of the main body and allowing compressed air to be introduced into the flow path; And it is formed on the rear side of the main body, it includes a powder suction port for sucking the powder by the negative pressure generated by the flow of the compressed air.

Preferably, the second vacuum ejector operates so that the powder stored in the mixing powder drum is drawn out of the mixing powder drum, passes through a circulation path of a certain length, and then flows back into the mixing powder drum, and the circulation path It extends from the lower portion of the mixing powder drum and is connected to the upper portion of the mixing powder drum, and the second vacuum ejector is installed on the lower side of the mixing powder drum on the circulation path.

Additionally, it further includes a full sensor for detecting whether the powder stored in the mixing powder drum is full.

In addition, the raw material mixing method using the raw material mixing device of the SLS type 3D printer according to the present invention, a) using a full sensor to check whether the powder mixing drum is full; b) measuring the weight (L1) of the used powder stored in the used powder drum using the first load cell; c) measuring the weight (L2) of the new powder stored in the new powder drum using the second load cell; and d) comparing the weight of the used powder measured by the first load cell with the weight of the new powder measured by the second load cell, so that the ratio of the used powder and the new powder in the mixing powder drum becomes a set ratio. controlling the operation of the second vacuum ejector, and the third vacuum ejector.

Preferably, in step d, assuming that the set ratio of the used powder and the new powder is A:B, the weight of the used powder (L1)×B and the value of the weight of the new powder (L2)×A In comparison, when the weight (L1)×B of the used powder is larger, the first vacuum ejector is operated to transfer the used powder from the used powder drum into the mixing powder drum, and the second vacuum ejector is operated to It is characterized in that the new powder is transferred into the mixing powder drum, and the third vacuum ejector is operated to mix the used powder and the new powder in the mixing powder drum.

Here, after step d, if the weight (L2) of the new powder is not 0, the first vacuum ejector, the second vacuum ejector, and the third vacuum ejector are continuously operated, and the weight (L2) of the new powder is 0 When the second vacuum ejector is stopped, the operation of the first vacuum ejector and the third vacuum ejector is stopped when the weight (L1)×B of the used powder becomes smaller than the weight (L2)×A of the new powder. characterized by stopping.

Preferably, in step d, assuming that the set ratio of the used powder and the new powder is A:B, the weight of the used powder (L1)×B and the value of the weight of the new powder (L2)×A In comparison, if the value of the weight (L2) × A of the new powder is larger, the first vacuum ejector is operated to transfer the used powder from the used powder drum into the mixing powder drum, and the second vacuum ejector is operated to It is characterized in that the new powder is transferred into the mixing powder drum, and the third vacuum ejector is operated to mix the used powder and the new powder in the mixing powder drum.

Here, after step d, if the weight (L1) of the used powder is not 0, the first vacuum ejector, the second vacuum ejector, and the third vacuum ejector are continuously operated, and the weight (L1) of the used powder is 0 , stops the operation of the first vacuum ejector, and when the value of the new powder weight (L2) × A becomes smaller than the weight of the used powder (L1) × B, the operation of the second vacuum ejector and the third vacuum ejector is stopped. characterized by stopping.

According to the present invention, the used powder and the new powder can be transferred and mixed into the mixing powder drum by using a vacuum ejector without using a separate transfer mechanism such as a transfer screw and a separate mixing mechanism such as a stirrer.

In addition, according to the present invention, compressed air and powder can be discharged with a vortex flow while being mixed with each other by the vacuum ejector. It is possible to increase the transfer and mixing efficiency of the powders.

In addition, according to the present invention, it is possible to properly transfer and mix the used powder and the new powder while maintaining the ratio of the used powder and the new powder in the mixing powder drum at a set ratio by comparing the weights of the new powder and the used powder.

1 is a conceptual diagram schematically showing the configuration of a raw material mixing apparatus of an SLS system 3D printer according to the present invention;
2 is a view showing a compressed air supply means of the raw material mixing device of the SLS method 3D printer according to the present invention;
3 is a cutaway perspective view showing the vacuum ejector of the raw material mixing device of the SLS type 3D printer according to the present invention;
4 is a flowchart schematically illustrating a raw material mixing method of the SLS method 3D printer according to the present invention.

Hereinafter, preferred embodiments of the raw material mixing apparatus and method of the SLS type 3D printer according to the present invention will be described in detail with reference to the accompanying drawings. For reference, in describing the present invention below, terms referring to the components of the present invention are named in consideration of the functions of each component, and therefore should not be construed as limiting the technical components of the present invention. will be

Referring to FIG. 1, the present invention provides a raw material mixing apparatus for an SLS-type 3D printer that forms a 3D product by sintering a powder as a raw material, comprising: a used powder drum 100 for storing used powder used for product molding; New powder drum 200 for storing new powder; a mixing powder drum 300 for receiving and mixing the used powder of the used powder drum 100 and the new powder of the new powder drum 200; a weight measuring means for measuring the weight of each of the used powder drum 100 , the new powder drum 200 , and the mixing powder drum 300 ; and transferring and mixing the powder stored in the used powder drum 100 , the new powder drum 200 , and the mixing powder drum 300 using compressed air according to the measurement result of the weight measuring means comprising means.

Here, the weight measuring means includes a first load cell 410 (LC1) installed under the used powder drum 100 to measure the weight of the used powder drum 100 and the weight of the used powder stored therein, the new powder It is installed in the lower part of the drum 200 to measure the weight of the new powder drum 200 and the weight of the new powder stored therein. It is installed in the lower part of the second load cell 420 (LC2), and the mixing powder drum 300 and a third load cell 430 (LC#3) for measuring the weight of the mixing powder drum 300 and the weight of the mixed powder stored therein.

The conveying and mixing means is installed on the first conveying path 10 connecting the used powder drum 100 and the mixing powder drum 300 and transfers the used powder stored in the used powder drum 100 to the mixed powder drum. The first vacuum ejector 510; E1 for transferring to 300 is installed on the second transfer path 20 connecting the new powder drum 200 and the mixing powder drum 300 to the new powder drum 200. A second vacuum ejector (520; E2) for transferring the stored new powder to the mixing powder drum 300, and a third vacuum ejector (530; E3) for mixing the used powder and new powder stored in the mixing powder drum 300 include

With this configuration, the used powder stored in the used powder drum 100 and the new powder stored in the new powder drum 200 are vacuum ejector ( It is possible to transfer and mix the mixing powder drum 300 using the 510 , 520 , and 530 .

Preferably, the raw material mixing device of the SLS type 3D printer according to the present invention is compressed air toward the conveying non-mixing means, that is, the first vacuum ejector 510 , the second vacuum ejector 520 , and the third vacuum ejector 530 . It further includes a compressed air supply means for supplying the.

Referring to FIG. 2 , the compressed air supply means includes an air compressor 610 , a filter 620 , a regulator 630 , a start valve 640 , and a solenoid valve 650 . The air compressor 610 compresses external air into high-pressure air. The filter 620 is installed on the downstream side of the air compressor 610 and serves to remove impurities and moisture in the compressed air generated from the air compressor 610 . The regulator 630 is installed on the downstream side of the filter 620 and serves to adjust the pressure of the compressed air passing through the filter 620 to a set pressure. The start valve 640 is installed on the downstream side of the regulator 630 , and the compressed air positively pressured by the regulator 630 is supplied to the first vacuum ejector 510 , the second vacuum ejector 520 , and/or the third vacuum It is turned on to be supplied to the ejector 530 side, or turned off so that the compressed air remaining inside the compressed air supply means is discharged to the outside. The solenoid valve 650 is installed on the downstream side of the start valve 640 and is connected to the first vacuum ejector 510 , the second vacuum ejector 520 , and the third vacuum ejector 530 . By controlling ON/OFF, it is controlled so that compressed air is supplied to the corresponding vacuum ejector. Additionally, a micro filter 660 for further filtering fine impurities and moisture of the compressed air that has passed through the filter 620 may be installed between the filter 620 and the regulator 630 .

By such a compressed air supply means, the compressed air compressed in the air compressor 610 has impurities and moisture removed and is positively pressured to a set pressure and supplied to the vacuum ejectors 510 , 520 , 530 , thereby providing powder by the vacuum ejectors. of uniform transport and mixing is possible.

Referring to FIG. 3 , each of the first vacuum ejector 510 , the second vacuum ejector 520 , and the third vacuum ejector 530 is configured to form a vortex by compressed air. Specifically, the vacuum ejector 510 includes a cylindrical pipe-shaped body 511 , a compressed air inlet 512 , and a powder suction port 513 .

The body 511 has a linear flow path 511a through which compressed air flows in one direction therein. The compressed air inlet 512 is formed in an annular or spiral shape along the circumference of the main body 511 , and allows the compressed air of the compressed air supply means to be introduced into the flow path 511a of the main body 511 . And, the powder inlet 513 is formed on the upstream side of the compressed air inlet 512, that is, on the rear side of the main body 511, and due to the negative pressure generated by the compressed air flow inside the main body 511, the main body 511 ), a negative pressure region NP is created on the rear side, and the powder inside the used powder drum 100 is sucked in the negative pressure region.

For convenience, only the first vacuum ejector 510 is illustrated in FIG. 3 , but the second vacuum ejector 520 and the third vacuum ejector 530 are also configured the same as the first vacuum ejector 510 .

Here, the compressed air inlet 512 is formed in an annular or spiral shape along the circumference of the main body 511, and the compressed air and powder transferred in the linear flow path 511a of the main body 511 are mixed with each other and have a vortex flow. It may be discharged to the outside of the body 511 . The vortex flow discharge of the compressed air and powder can increase the transfer and mixing efficiency of the powder.

Preferably, in the third vacuum ejector 520 , the powder stored in the mixing powder drum 300 is withdrawn to the outside of the mixing powder drum 300 and passes through the circulation path 30 of a predetermined length, and then the mixing powder drum 300 again. It works to flow into the inside of To this end, the circuit 30 extends from the lower portion of the mixing powder drum 300 and is connected to the upper portion of the mixing powder drum 300 , and the third vacuum ejector 300 is located on the lower side of the mixing powder drum on the circuit 30 . is installed on

With this configuration, the used powder and the new powder stored in the mixing powder drum 300 can be mixed with each other while circulating along the circulation path 30 by the third vacuum ejector 300 without using a separate stirring mechanism.

Additionally, the raw material mixing apparatus of the SLS type 3D printer according to the present invention further includes a full sensor 440 for detecting whether the powder stored in the mixing powder drum 300 is full. The pool sensor 440 is installed on the mixing powder drum 300 and serves to determine whether the mixing process is started by checking the amount of mixed powder in the mixing powder drum 300 .

Hereinafter, a raw material mixing method using the raw material mixing apparatus of the SLS type 3D printer according to the present invention will be described with reference to FIGS. 1 to 4 .

First, it is checked whether the mixed powder of the used powder and the new powder is filled in the mixed powder drum 300 using the full sensor 440 of the mixed powder drum 300 . As a result of the measurement of the full sensor 440 , if the mixing powder is full in the mixing powder drum 300 , the raw material mixing process is ended, otherwise the raw material mixing process is started.

Next, the weight L1 of the used powder stored in the used powder drum 100 is measured using the first load cell 410 installed under the used powder drum 100 . In this case, the weight L1 of the used powder may be measured by calculating the weight difference between the weight of the used powder drum 100 that is empty and the weight of the used powder drum 100 containing the used powder.

Next, the weight L2 of the new powder stored in the new powder drum 200 is measured using the second load cell 420 installed in the new powder drum 200 . In this case, the weight L2 of the new powder may be measured by calculating the difference in weight between the empty new powder drum 200 and the new powder drum 200 containing the new powder.

Next, by comparing the weight (L1) of the used powder measured by the first load cell 410 with the weight (L2) of the new powder measured by the second load cell 420, the used powder of the mixing powder drum 300 is The operation of the first vacuum ejector 510 , the second vacuum ejector 520 , and the third vacuum ejector 530 is controlled so that the ratio of the powder and the new powder becomes a set ratio.

Here, assuming that the set ratio of the used powder and the new powder is A:B, compare the weight of the used powder (L1)×B with the value of the weight of the new powder (L2)×A to determine the weight of the used powder ( When the value of L1)×B is larger, the first vacuum ejector 510 is operated to transfer the used powder of the used powder drum 100 into the mixing powder drum 300 , and the second vacuum ejector 520 is operated to transfer the new powder of the new powder drum 200 into the mixing powder drum 300 , and operate the third vacuum ejector 530 to mix the used powder and the new powder in the mixing powder drum 300 .

Subsequently, if the weight (L2) of the new powder is not 0, the first vacuum ejector 510, the second vacuum ejector 520, and the third vacuum ejector 530 are continuously operated, and the weight of the new powder (L2) ) becomes 0, the operation of the second vacuum ejector 520 is stopped. In addition, when the value of the weight (L1)×B of the used powder is smaller than the value of the weight (L2)×A of the new powder, the operation of the first vacuum ejector 510 and the third vacuum ejector 550 is stopped.

On the other hand, by comparing the value of the weight (L1)×B of the used powder and the value of the weight (L2)×A of the new powder, if the value of the weight (L2)×A of the new powder is larger, the first vacuum ejector 510 ) to transfer the used powder of the used powder drum 100 into the mixing powder drum 300, and operate the second vacuum ejector 520 to mix the new powder in the new powder drum 200 into the mixing powder drum 300. It is transferred inside, and the third vacuum ejector 530 is operated to mix the used powder and the new powder in the mixing powder drum 300 .

Subsequently, if the weight (L1) of the used powder is not 0, the first vacuum ejector 510, the second vacuum ejector 520, and the third vacuum ejector 530 are continuously operated, and the weight of the used powder (L1) ) becomes 0, the operation of the first vacuum ejector 510 is stopped. In addition, when the value of the weight (L2)×A of the new powder is smaller than the value of the weight (L1)×B of the used powder, the operation of the second vacuum ejector 520 and the third vacuum ejector 530 is stopped.

As described above, the raw material mixing method of the SLS method 3D printer according to the present invention compares the weights of the new powder and the used powder, and maintains the ratio of the used powder and the new powder in the mixing powder drum at a set ratio, while mixing the used powder and the new powder. It can be transported and mixed appropriately.

The embodiments of the present invention described above are merely illustrative of the technical idea of the present invention, and the protection scope of the present invention should be interpreted by the following claims. In addition, various modifications and variations are possible without departing from the essential characteristics of the present invention by those of ordinary skill in the art to which the present invention pertains. It should be interpreted as being included in the scope of rights.

10: first transfer path 20: second transfer path
30: circuit 100: used powder drum
200: new powder drum 300: mixing powder drum
410: first load cell 420: second load cell
430: third load cell 440: pull sensor
510: first vacuum ejector 511: body
511a: straight flow path 512: compressed air inlet
513: powder inlet NP: negative pressure area
520: second vacuum ejector 530: third vacuum ejector
610: air compressor 620: filter
630: regulator 640: start valve
650: solenoid valve 660: micro filter

Claims (11)

A raw material mixing method using a raw material mixing device of an SLS system 3D printer, comprising:
a) using a full sensor to check whether the mixing powder drum is full of powder;
b) measuring the weight (L1) of the used powder stored in the used powder drum using the first load cell;
c) measuring the weight (L2) of the new powder stored in the new powder drum using the second load cell; and
d) Comparing the weight of the used powder measured by the first load cell and the weight of the new powder measured by the second load cell, the first vacuum ejector, the second controlling the operation of the vacuum ejector, and a third vacuum ejector,
In step d, assuming that the set ratio of the used powder and the new powder is A:B, compare the weight of the used powder (L1)×B with the value of the weight of the new powder (L2)×A to compare the used powder When the value of weight (L1)×B is larger, the first vacuum ejector is operated to transfer the used powder in the used powder drum into the mixing powder drum, and the second vacuum ejector is operated to mix the new powder in the new powder drum. A raw material mixing method of an SLS method 3D printer, in which the used powder and the new powder in the mixing powder drum are mixed by transferring them into the powder drum and operating the third vacuum ejector.
The method of claim 1,
After step d,
If the weight (L2) of the new powder is not 0, continue to operate the first vacuum ejector, the second vacuum ejector, and the third vacuum ejector,
When the weight (L2) of the new powder becomes 0, the operation of the second vacuum ejector is stopped,
The raw material mixing method of the SLS method 3D printer, which stops the operation of the first vacuum ejector and the third vacuum ejector when the weight of the used powder (L1)×B becomes smaller than the weight of the new powder (L2)×A.
The method of claim 1,
In step d above, assuming that the set ratio of the used powder and the new powder is A:B, compare the weight of the used powder (L1)×B with the value of the weight of the new powder (L2)×A to compare the new powder When the value of weight (L2)×A of is larger, operate the first vacuum ejector to transfer the used powder in the used powder drum into the mixing powder drum, and operate the second vacuum ejector to mix the new powder in the new powder drum A raw material mixing method of an SLS method 3D printer, in which the used powder and the new powder in the mixing powder drum are mixed by transferring them into the powder drum and operating the third vacuum ejector.
4. The method of claim 3,
After step d,
If the weight (L1) of the used powder is not 0, continue to operate the first vacuum ejector, the second vacuum ejector, and the third vacuum ejector,
When the weight (L1) of the used powder becomes 0, the operation of the first vacuum ejector is stopped,
The raw material mixing method of the SLS method 3D printer, which stops the operation of the second vacuum ejector and the third vacuum ejector when the value of the new powder weight (L2)×A becomes smaller than the weight of the used powder (L1)×B. delete delete delete delete delete delete delete

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