KR102572001B1 - Apparatus for controlling 3d printing considering a viscosity and surface tension of output material and method thereof - Google Patents

Abstract

The present specification discloses a 3D printing control device and method capable of improving the quality of output. By setting the optimal filling density according to the viscosity characteristics of the output material, it is possible to set the minimum output path. In setting the output path, the width of the output path may be set in consideration of the spreading characteristics of the viscosity of the output material after being discharged. The viscosity characteristics of the output material can be calculated by measuring the time at which two ejected droplets meet. By setting the optimal filling density according to the surface tension characteristics of the output material, it is possible to set the minimum output path. In setting the output path, the width of the output path may be set in consideration of the spreading characteristics of the output material after being ejected according to the surface tension of the output material. The surface tension characteristics of the output material can be calculated by measuring the radius of the ejected droplet.

Description

3D printing control device and method considering viscosity and surface tension of output material

The present invention relates to 3D printing.

3D bioprinting, which is a field of application and development of 3D printing technology, is based on 3D printing technology and uses extracellular matrix (ECM) such as collagen or bio-ink that imitates it. It is a technology to create a desired shape by combining ink with cells and other biomaterials. Currently, various methods of 3D bioprinting are being developed according to the desired purpose and biological environment, and various bioinks are also being studied.

1 is an example of 3D printing according to the prior art.

Referring to FIG. 1 , when an output material is a liquid, a scaffold of a 3D mesh structure in a solid state is formed, and an output material (eg, bioink) in a liquid state is laminated. At this time, the material of the scaffold is a material that is naturally decomposed, and 3D printing proceeds in a way that it is naturally decomposed over time after output.

In the case of 3D printing according to such a conventional method, a desired shape can be produced only when output variables are set to optimum conditions according to the output material and the 3D shape to be modeled. When the type of liquid, which is an output material, is changed or the mixing ratio of the same liquid is changed, surface tension and viscosity, which are inherent properties of the liquid, may change, which may affect output quality.

Therefore, whenever the output material is changed, it takes a lot of time and money to find the output setting to have the optimal condition for the new material. Furthermore, there is a problem in that a lot of cost and time is consumed because the output setting value of 3D printing suitable for the output material must be found through several trials and errors. In addition, this method has a disadvantage in that it takes a long time to print because a 3D shape is produced by stacking several layers in order to improve the surface quality of the output.

Republic of Korea Registered Patent Publication 　10-1828345 (2018.02.06)

An object of the present specification is to provide a 3D printing control device and method capable of improving the quality of output.

This specification is not limited to the above-mentioned tasks, and other tasks not mentioned will be clearly understood by those skilled in the art from the description below.

3D printing control device according to the present specification for solving the above problems, processor for setting the width of the output line by the viscosity or surface tension characteristics of the output material according to the height of the dispenser needle from which the output material is discharged; can

According to one embodiment of the present specification, the processor determines the viscosity or surface tension characteristics of the output material according to the height of the dispenser needle higher and lower than the reference height (hereinafter referred to as 'reference height') for determining the surface tension and viscosity flow according to the height of the needle. You can set the width of the output line by

According to one embodiment of the present specification, the reference height TH _Z may be a value calculated by the following formula.

=

: Standard height for determining surface tension and viscosity flow, : Coefficient, : needle inner diameter, : Viscosity ratio of the output material

According to one embodiment of the present specification, the processor may set the width of the output line according to the surface tension characteristics of the output material when the height of the dispenser needle is equal to or less than the reference height.

According to one embodiment of the present specification, the processor may calculate the width (L _D ) of the output line through the following formula.

: Print filling density considering surface tension, : needle inner diameter, : Output line spacing, H: Output height, : the radius of the water drop, : Surface tension ratio of water and the material to be printed, : Volume of droplet printed for surface tension measurement

According to one embodiment of the present specification, when the height of the dispenser needle exceeds the reference height, the processor considers the speed of the liquid discharged through the needle and the moving speed ratio of the needle (hereinafter referred to as 'speed ratio') to determine the viscosity or surface The width of the output line can be set according to the tension characteristics.

According to one embodiment of the present specification, the processor sets the width of the output line according to the viscosity characteristics of the output material when the speed ratio is greater than or equal to a preset reference ratio, and sets the width of the output line when the speed ratio is less than the preset reference ratio. The width of the output line can be set by the surface tension characteristics.

According to one embodiment of the present specification, when setting the width of the output line according to the surface tension characteristics of the output material, the processor may calculate the width (L _D ) of the output line through the following formula.

: Print filling density considering surface tension, : needle inner diameter, : Output line spacing, H: Output height, : the radius of the water drop, : Surface tension ratio of water and the material to be printed, : Volume of droplet printed for surface tension measurement

According to one embodiment of the present specification, when setting the width of the output line according to the viscosity characteristics of the output material, the processor may calculate the width LD of the output line through the following formula.

: Output filling density considering viscosity, : needle inner diameter, : output line spacing, : the maximum time at which printed lines meet, : Viscosity ratio of water and output material, : the time it took for the water to meet each other, : The time it takes for droplets to attach during printing, : Needle height at output, : Coefficient

According to one embodiment of the present specification, the surface tension characteristic of the output material may be a ratio of the surface tension of the output material to the surface tension of water.

According to one embodiment of the present specification, the surface tension ratio of the output material may be calculated using a radius value of a circular drop formed after the dispenser needle is ejected from the bottom by a preset distance.

According to one embodiment of the present specification, the viscosity characteristic of the output material may be a viscosity ratio of the output material to the viscosity of water.

According to one embodiment of the present specification, the viscosity ratio of the output material is calculated using the time value at which two drops meet after two dispenser needles are discharged while maintaining a preset distance apart from the bottom surface by a preset distance it could be

According to one embodiment of the present specification, the processor may further set the extrusion length according to the formula below.

: Volume of output, : inner diameter of the dispenser, : extrusion length

Other specific details of the invention are included in the detailed description and drawings.

According to one aspect of the present specification, when the output material is a liquid mixture, suitable output settings may be created to improve the quality of the output material.

According to another aspect of the present specification, when printing a liquid mixture, it is possible to complete printing in the shortest time with the minimum number of layers by optimally setting the filling density and speed of the print object.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

1 is an example of 3D printing according to the prior art.
2 is a reference diagram to help understand the filling density.
3 is a schematic flow diagram of a method for finding the viscosity of an output material according to the present disclosure.
4 is a reference diagram for a process in which two droplets meet after being ejected.
5 is a reference diagram for a process of filling a space while spreading the material printed along two output lines.
6 is a schematic flow chart of a method for finding the surface tension of an output material according to the present specification.
7 is a reference diagram to aid understanding of surface tension.
8 is a reference image for an example of an output shape.

Advantages and features of the invention disclosed in this specification, and methods for achieving them, will become clear with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present specification is not limited to the embodiments disclosed below and may be implemented in a variety of different forms, and only the present embodiments make the disclosure of the present specification complete, and are common in the art to which the present specification belongs. It is provided to fully inform the technical person (hereinafter referred to as 'one skilled in the art') of the scope of the present specification, and the scope of rights of the present specification is only defined by the scope of the claims.

Terms used in this specification are for describing the embodiments and are not intended to limit the scope of the present specification. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. As used herein, "comprises" and/or "comprising" does not exclude the presence or addition of one or more other elements other than the recited elements.

Like reference numerals throughout the specification refer to like elements, and “and/or” includes each and every combination of one or more of the recited elements. Although "first", "second", etc. are used to describe various components, these components are not limited by these terms, of course. These terms are only used to distinguish one component from another. Accordingly, it goes without saying that the first element mentioned below may also be the second element within the technical spirit of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with meanings commonly understood by those skilled in the art to which this specification belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless explicitly specifically defined. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In 3D printing using a liquid material, results may vary depending on the characteristics of the liquid material and the output height. When the dispenser needle that discharges liquid material is printed close to the floor, the behavior of the liquid material printed will be dominantly influenced by the surface tension of the liquid material. The behavior of a liquid material to be used will be influenced predominantly by the viscosity of the liquid material. For example, if a high-viscosity liquid material is printed with a low filling density, an empty space may occur between paths (output lines) along which the dispenser needle moves due to lack of spreading of the printed liquid. In addition, when the moving speed of the dispenser needle is faster than the speed of filling the empty space between the printed liquid materials, a bubble-shaped space may be generated inside the final printed object, and the thickness of the printed object may increase. Therefore, it is necessary to set the height of the dispense needle, the output speed, and/or the output path optimized according to the characteristics of the output material.

For reference, in this specification, a "dispenser needle" is a part included in a 3D printer, and is a place where liquid, which is an output material, is finally discharged to the outside. In general, 3D printing outputs a material while a dispenser needle moves in a zig-zag manner. At this time, the distance between the paths (output lines) along which the needles moved may vary according to the filling density. In this specification, "filling density (Density _print )" is the ratio of the output line spacing to the inner diameter of the needle. Expressing this mathematically, it is as follows.

: Output filling density

: needle inner diameter

: Output line spacing

2 is a reference diagram to help understand the filling density.

Referring to FIG. 2 , an example in which the spacing of the output lines is different according to the power density when outputting the same shape is shown. When the spreading property of the output material is high, as shown in FIG. On the other hand, when the spreading property of the output material is low, as shown in FIG. Therefore, if the power density is appropriately set according to the characteristics of the output material, a desired shape can be output with the minimum output line, and the output time can be reduced. In this specification, a method for finding an optimal output setting considering viscosity and surface tension among characteristics of an output material will be described.

<Relational expression of the spacing of the output line considering the viscosity of the output material>

First, a method for finding the viscosity of the output material, which is one of the characteristics of the output material, will be described. If the information on the viscosity of the output material is known in advance, this process can be omitted. It is assumed that the liquid material output in this specification is an incompressible Newtonian fluid.

3 is a schematic flow diagram of a method for finding the viscosity of an output material according to the present disclosure.

Referring to FIG. 3 , in step S10, the processor controls the two dispenser needles to be separated from the floor by a preset distance and maintain a preset interval. When the output material is printed, the spreading degree of the liquid may vary depending on the ambient temperature, pressure, material and geometry of the bottom surface. Therefore, when measuring the viscosity of the output material, it is assumed that the ambient temperature and pressure, the material and geometry of the bottom surface are fixed. Preferably, the temperature, pressure, material and shape of the bottom surface are the same as those of the environment to be output. In addition, even if the output material is changed, it is preferable that the distance between the needle and the bottom surface and the distance between the two needles are always constant.

In the next step S11, the processor controls the two dispenser needles to simultaneously discharge the preset amount of the output material. At this time, the two liquid droplets discharged from the two needles meet each other while spreading in all directions due to the energy they have.

In the next step S12, the processor may calculate the viscosity value of the output material using the time value at which the two droplets meet.

4 is a reference diagram for a process in which two droplets meet after being ejected.

4(a) is right after the output material is discharged (t ₀ ). It can be seen that two drops (Liquid) fell on the bottom surface (Solid) at the distance (L _DT ) between the two needles. After a while, as shown in (b) of FIG. 4, the two drops meet. The time taken for the two droplets to meet after ejection (t _f ) is proportional to the viscosity of the output material.

According to one embodiment of the present specification, the time required for the two drops to meet may be directly input. For example, it is a method in which a person uses a stopwatch to measure the time at which two drops meet, and directly inputs the time value.

According to another embodiment of the present specification, time may be measured using a camera. A camera is set up to photograph the two drops. Preferably, the camera may be installed to photograph the two ejected droplets from a vertical upward direction. In addition, the processor sets the start time "t ₀ " when executing step S12, and the camera can continuously output images until the two drops spread and meet. The processor may analyze the image output from the camera to determine the point in time t _f at which the two drops meet.

Meanwhile, in the present specification, the viscosity of the output material may be calculated as a viscosity value as a relative ratio value based on the viscosity of water droplets. That is, the relative viscosity value of the output material is the ratio ( ) can be calculated using The time the two droplets meet is the interval between the droplets ( ) and the height of the needle ( ) is inversely proportional to Therefore, their relationship can be expressed as Equation 2 below.

: Viscosity ratio of water and print material

: Viscosity of the output material

: viscosity of water

: The time it took for the printed materials to meet each other when testing

: time taken for water to meet each other

: drop time

: 2 needle spacing when testing

: Needle height when testing

: Coefficient

On the other hand, when performing actual output rather than a test for measuring viscosity, a needle height different from the preset needle height ( ) and the spacing between output lines ( ) can be used. At this time, the time the printed drops spread and meet ( ) can be represented by the relationship of Equation 3 below.

: The time it takes for droplets to attach during printing

: spacing of output lines

: Needle height when printing

Hereinafter, a method for determining the optimal output setting in consideration of the viscosity characteristics of the output material will be described. Environment where the viscosity of the output material has a lot of influence, for example, when the height of the dispenser needle is relatively high, filling density considering the viscosity ( ) is proportional to the viscosity. In this case, the curing speed of the output material is slower than the output speed, and the spreading speed of the output material according to the viscosity of the output material ( ) is assumed to be faster than the output speed.

5 is a reference diagram for a process of filling a space while spreading the material printed along two output lines.

Figure 5 (a) is a state immediately after output, Figure 5 (b) is a state that the output material spreads, Figure 5 (c) is a state that the output material meets each other and fills the space. Referring first to (a) of FIG. 5 , a relational expression such as Equation 4 below may be derived.

: Output line width immediately after output

: needle inner diameter

: height of output line

: Output line spacing

: Distance of empty spaces between output lines

And referring to (b) and (c) of FIG. 5 , a relational expression such as Equation 5 below may be derived.

: output line width after t time elapses

: height of the output line after t time has elapsed

: distance of free space between output lines after t time has elapsed

: Width just before the output lines meet

: Distance of empty space just before two lines meet (value is 0)

: Change in width until the two lines meet

Filling density considering viscosity ( ) is proportional to the viscosity, so when expressed as an equation, it can be expressed as in Equation 6 below.

: Output filling density considering viscosity

: maximum distance between output lines

: Maximum time at which printed lines meet

Filling density considering the low viscosity calculated by entering the viscosity ratio value of the output material in Equation 6 ( ) can be output. At this time, the interval between the output lines ( ) is the maximum boundary value considering the output speed set below to satisfy the condition. The maximum boundary value ( ) is the maximum time at which the output lines meet ( represents the width that the output line spreads to both sides during and can be derived from Equation 3.

Meanwhile, in FIG. 5 , it is assumed that two output lines are generated simultaneously for convenience of understanding, but the output lines do not necessarily need to be generated simultaneously. In the case of one needle, two output lines may be generated with a time difference. Therefore, the method described herein is not limited according to the generation point of the output line.

<The relational expression of the spacing of the output line considering the surface tension of the output material>

Next, in this specification, a method for finding an optimal output setting considering the surface tension of the output material, which is one of the characteristics of the output material, will be described. First, a method for finding the surface tension of the output material, which is one of the characteristics of the output material, will be described. If information on the surface tension of the output material is known in advance, this process can be omitted. It is assumed that the liquid material output in this specification is an incompressible Newtonian fluid.

6 is a schematic flow chart of a method for finding the surface tension of an output material according to the present specification.

Referring to FIG. 6 , in step S20, the processor controls the dispenser needle to be separated from the floor by a preset distance. When the output material is printed, the spreading degree of the liquid may vary depending on the ambient temperature, pressure, material and geometry of the bottom surface. Therefore, when measuring the surface tension of the output material, it is assumed that the ambient temperature and pressure, the material and geometric shape of the bottom surface are fixed. Preferably, the temperature, pressure, material and shape of the bottom surface are the same as those of the environment to be output. In addition, even if the output material is changed, it is preferable that the distance between the needle and the bottom surface is always constant.

In the next step S21, the processor controls a preset amount of output material to be discharged from the dispenser needle. At this time, the discharged liquid material spreads to form a circular shape, and a difference occurs in the contact angle and radius due to the surface tension of the liquid material.

The surface tension value of the output material may be calculated using the radius value of the circle formed in the next step S22.

According to one embodiment of the present specification, the radius of a circle (drop) formed by discharging the output material may be directly measured. For example, it is a method in which a person measures the radius of a drop using a ruler and directly inputs the radius value.

According to another embodiment of the present specification, the radius of a circle (drop) formed by ejecting the output material may be measured using a camera. A camera is set up to photograph the droplet. Preferably, the camera may be installed to photograph the ejected droplets from a vertical upward direction. The processor may calculate the radius of the drop by analyzing the image output from the camera.

7 is a reference diagram to aid understanding of surface tension.

Referring to FIG. 7, the pressure difference between the outside and inside of the liquid ( ) is the surface tension ( ) and the radius of the droplet ( ) is inversely proportional to If this relationship is expressed using the Young-Laplace Equation, it can be expressed as in Equation 7 below.

: Force per unit length of contact surface between solid-gas, solid-liquid, and liquid-gas

: contact angle

: surface tension

: liquid internal pressure

: gas pressure

In Equation 7, ignoring the contact angle and arranging using only the measured radius of the output material, it can be expressed as Equation 8 below.

: material density

: Surface tension of the printed material

: Volume of droplet printed for surface tension measurement

: gravitational acceleration

And the radius ratio of the output material ( ) can be expressed as Equation 9 below by arranging Equation 8 based on water droplets.

/

: Ratio of surface tension between water and the material to be printed

: Radius of output material droplet

: the radius of the water drop

: Coefficient

In Equation 9, it is assumed that the amount of water droplets is the same as the amount of droplets of the output material. When measuring the surface tension of the output material, a preset amount is discharged, but when performing actual 3D printing using the output material, it can be discharged at various speeds and extrusion amounts. Therefore, when the actual discharged amount is “V”, the radius (r) in which the output material spreads can be expressed as in Equation 10 below.

: Output material droplet radius per unit output length

: Volume of droplets of output material per unit output length

Hereinafter, a method for determining an optimal output setting in consideration of surface tension characteristics of an output material will be described. Environment where the surface tension of the output material has a lot of influence. For example, when the height of the dispenser needle is relatively low, the filling density considering the surface tension ( ) is proportional to the surface tension. Therefore, in the case of printing with a material having a small surface tension, the filling density may be lowered, and in the case of printing with a material having a high surface tension, the filling density may be increased. In this case, the curing speed of the output material is slower than the output speed, and the spreading speed of the output material according to the surface tension of the output material ( ) is assumed to be faster than the output speed. The relational expression for the surface tension ratio and the filling density can be expressed as Equation 11 below.

: Droplet radius per unit output length

: Volume of droplets per unit output length

: Print filling density considering surface tension

: volume of output

H: the height of the output

: total length of the output path

In the relationship between Equation 11 and Equation 1, the inner diameter of the needle ( ) is determined by the hardware in the actual output environment, considering the surface tension characteristics of the output material, the appropriate output line spacing ( ) can be set. At this time, the interval between the output lines ( ) is the maximum boundary value considering the output speed set below to satisfy the condition. The maximum boundary value ( ) is the maximum time at which the output lines meet ( represents the width that the output line spreads to both sides during and can be derived from Equation 3.

<Select a relational expression related to the spacing of output lines according to the output environment>

Previously, the relational expression related to the viscosity of the output material and the relational expression related to the surface tension were examined. For output in the shortest time, an output layer should be determined according to the output shape, and the minimum output path should be optimally set for each layer. As described above, when the dispenser needle from which liquid material is discharged is printed in close proximity to the floor, the behavior of the liquid material to be printed will be dominantly influenced by the surface tension of the liquid material, and In the case of printing, the behavior of the liquid material to be printed will be dominantly influenced by the viscosity of the liquid material. Therefore, it can first be determined which relational expression to use according to the distance between the needle and the bottom surface. At this time, the distance between the needle and the bottom surface may vary depending on the shape to be printed.

8 is a reference image for an example of an output shape.

Referring to (a) of FIG. 8 , a pot-shaped mold can be confirmed. The pot-shaped mold has an empty inside, and a liquid material may be output therein. At this time, the jar shape can be divided into two parts. The narrow part from the bottom corresponds to the body of the jar, and the body has a height H1 higher than that of the side. And the upper part corresponding to the spout of the jar has a lower height (H2) than the side. When printing such a shape, it is preferable to set the height of the needle relatively low so that the body is dominantly influenced by the characteristic, that is, the surface tension of the output material, so that the body is stacked higher than the characteristic of the output material spreading. In addition, it is preferable to set the height of the needle relatively high so that the spout is predominantly influenced by the spreading characteristics of the output material, that is, the viscosity of the output material. Such a state is shown in FIG. 8(b). The height of the needle means the distance from the bottom surface or a previously printed layer. Meanwhile, in the following description considering the example of FIG. 8, it is assumed that the output height is arbitrarily set according to the output shape, but an embodiment in which the processor analyzes the output shape and changes the height according to the entire or partial shape of the output is also possible. .

According to the present specification, the processor may set the width of the output line according to the viscosity or surface tension characteristics of the output material according to the height of the dispenser needle through which the output material is discharged. Depending on the characteristics of the output material, surface tension characteristics will prevail below a certain height, and viscosity characteristics will prevail above a certain height. At this time, the criterion for determining whether the flow of the output material according to the height of the needle is the flow according to the surface tension or the flow according to the viscosity is the inner diameter of the needle ( ), and the viscosity ratio of the output material ( ) can be inversely proportional to If this is expressed as an equation, it is shown in Equation 12 below.

: Standard height for determining surface tension and viscosity flow according to needle height

: Coefficient

The processor may set the width of the output line according to the viscosity or surface tension characteristics of the output material according to the height of the dispenser needle higher or lower than the surface tension and viscosity flow determination standard height (hereinafter referred to as 'standard height').

In this case, the processor may set the width of the output line according to the surface tension characteristics of the output material when the height of the dispenser needle is equal to or less than the reference height. In this case, the processor may calculate the width L _D of the output line through Equation 13 below.

: Print filling density considering surface tension, : needle inner diameter, : Output line spacing, H: Output height, : the radius of the water drop, : Surface tension ratio of water and the material to be printed, : Volume of droplet printed for surface tension measurement

Since Equation 13 has been described above, a repetitive description thereof will be omitted.

On the other hand, when the height of the dispenser needle exceeds a preset reference height, the processor considers the speed of the liquid discharged through the needle and the ratio of the moving speed of the needle (hereinafter referred to as 'speed ratio') to output by viscosity or surface tension characteristics You can set the line width. The speed ratio is expressed as Equation 14 below.

: Average velocity of the liquid discharged from the needle

: Output average speed (needle output movement speed)

The velocity of the liquid ejected through the needle ( ) can be obtained using the continuity equation of the liquid. If this is expressed as a mathematical formula, it is as shown in Equation 15 below.

: Dispenser inner diameter cross-sectional area

: Needle inner diameter cross-sectional area

output average speed ( ) is the height of the layer (regardless of surface tension and viscosity) ), the physical size of the dispenser ( ) is determined by If this is expressed as an equation, it is equal to Equation 16.

In Equation 16, the power density may be applied depending on the viscosity and surface tension. The processor sets the width of the output line according to the viscosity characteristics of the output material when the speed ratio is greater than or equal to the preset reference ratio, and sets the width of the output line according to the surface tension characteristics of the output material when the speed ratio is less than the preset reference ratio. Width can be set. Since the width of the output line according to each case is described in Equations 6 and 11, repetitive descriptions are omitted.

On the other hand, instead of lowering the filling density, the extrusion length ( ) is increased, the printed material spreads to the side to fill the empty space, and the output can be completed while minimizing the output path. extrusion length ( ) means the length of the material output from the dispenser. Multiplying the inner diameter area of the dispenser by the extrusion length means the amount of material used for printing. In this case, the extrusion length ( ) can be expressed as in Equation 17 below.

: volume of output

: inner diameter of dispenser

: Dispenser extrusion length

For reference, in the case of a liquid having a large viscosity value, a large pressure is required to discharge the liquid through the dispenser, so that excessive force is applied to the dispenser, so the inner diameter of the needle ( ), a large needle can be used.

The processor may include an application-specific integrated circuit (ASIC) known in the art to which the present invention pertains, other chipsets, logic circuits, registers, communication modems, data processing devices, etc. to execute the above-described calculation and various control logics. there is. Also, when the above-described control logic is implemented as software, the processor may be implemented as a set of program modules. At this time, the program module may be stored in the memory device and executed by the processor.

The above-described computer program is C / C ++, C #, JAVA that can be read by a processor (CPU) of the computer through a device interface of the computer so that the computer reads the program and executes the methods implemented as a program. , Python, may include code coded in a computer language such as machine language. These codes may include functional codes related to functions defining necessary functions for executing the methods, and include control codes related to execution procedures necessary for the processor of the computer to execute the functions according to a predetermined procedure. can do. In addition, these codes may further include memory reference related codes for which location (address address) of the computer's internal or external memory should be referenced for additional information or media required for the computer's processor to execute the functions. there is. In addition, when the processor of the computer needs to communicate with any other remote computer or server in order to execute the functions, the code uses the computer's communication module to determine how to communicate with any other remote computer or server. It may further include communication-related codes for whether to communicate, what kind of information or media to transmit/receive during communication, and the like.

The storage medium is not a medium that stores data for a short moment, such as a register, cache, or memory, but a medium that stores data semi-permanently and is readable by a device. Specifically, examples of the storage medium include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc., but are not limited thereto. That is, the program may be stored in various recording media on various servers accessible by the computer or various recording media on the user's computer. In addition, the medium may be distributed to computer systems connected through a network, and computer readable codes may be stored in a distributed manner.

Although the embodiments of the present specification have been described with reference to the accompanying drawings, those skilled in the art to which the present specification pertains can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. you will be able to understand Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (14)

Determination of surface tension and viscosity flow according to the height of the dispenser needle When it is below the standard height (hereinafter referred to as 'standard height') The width of the output line is set according to the surface tension characteristics of the output material, and the height of the dispenser needle exceeds the standard height A processor for setting the width of the output line by viscosity or surface tension characteristics in consideration of the speed of the liquid discharged through the needle and the ratio of the movement speed of the needle (hereinafter referred to as 'speed ratio'); including,
The surface tension characteristic of the output material is the ratio of the surface tension of the output material to the surface tension of water,
The viscosity characteristic of the output material is the ratio of the viscosity of the output material to the viscosity of water,
the processor,
When the speed ratio is greater than or equal to a preset reference ratio, the width of the output line is set according to the viscosity characteristics of the output material, and when the speed ratio is less than the preset reference ratio, the width of the output line is set according to the surface tension characteristics of the output material, ,
The reference height (TH _Z ) is a 3D printing control device that is a value calculated by the formula below.
=
: The standard height for determining surface tension and viscosity flow, : Coefficient, : needle inner diameter, : Viscosity ratio of the output material
delete delete delete delete delete delete The method of claim 1,
When the processor sets the width of the output line by the surface tension characteristics of the output material, the 3D printing control device, characterized in that for calculating the width (L _D ) of the output line through the formula below.

: Print filling density considering surface tension, : needle inner diameter, : Output line spacing, H: Output height, : the radius of the water drop, : Surface tension ratio of water and the material to be printed, : Volume of droplet printed for surface tension measurement The method of claim 1,
3D printing control device, characterized in that the processor calculates the width (LD) of the output line through the following formula when setting the width of the output line by the viscosity characteristics of the output material.

: Output filling density considering viscosity, : needle inner diameter, : output line spacing, : the maximum time at which printed lines meet, : Viscosity ratio of water and output material, : the time it took for the water to meet each other, : The time it takes for droplets to attach during printing, : Needle height at output, : Coefficient delete The method of claim 1,
The surface tension ratio of the output material is a 3D printing control device that is calculated using the radius value of the circular drop formed after the dispenser needle is discharged in a state away from the bottom surface by a preset distance. delete The method of claim 1,
The viscosity ratio of the output material is calculated using the time value at which the two drops meet after the two dispenser needles are discharged while maintaining a preset distance apart from the bottom surface by a preset distance. 3D printing control device. The method of claim 1,
The processor, 3D printing control device, characterized in that for further setting the extrusion length according to the formula below.

: Volume of output, : inner diameter of the dispenser, : extrusion length