JPH06210999A - Forming method of three-dimensional shape - Google Patents

Abstract

PURPOSE:To form three-dimensional shape in an epoch-making manner at a low cost by a method wherein ink is discharged selectively onto and solidified on a shaped workpiece set in a shape-forming space which is kept at a temperature of the point of solidification of the ink or below. CONSTITUTION:A three-dimensionally shaped substance is formed by repeating an operation of discharging ink selectively onto and solidifying it on a shaped workpiece set on a support, with a nozzle or the support moved in parallel, in a shape-forming space kept at the temperature of the point of solidification of the ink. Concretely, a device for forming the three-dimensionally shaped substance is held in a heat-insulating structure case 1, the shape-forming space 2 kept at the temperature of the freezing point or below is provided, and a main scanning moving rail 3 which can make the nozzle 5 operate along it is disposed. Besides, subordinate scanning moving rails 4a and 4b along which the main scanning moving rail 3 can operate are fixed on the wall surfaces of the heat-insulating structure case 1 being opposite to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modeling a three-dimensional object which can be used as a prototype model or a master model based on voxel data output from a three-dimensional model built in a computer or a CT scanner.

[0002]

2. Description of the Related Art A stereolithography method is known as a conventional three-dimensional shaping method. This is because the UV laser device that can move the liquid surface of the UV curable resin freely in XY along the liquid surface selectively irradiates the laser to cure the resin on the surface layer of the liquid surface to form horizontal slices, and then the slice thickness. Only the process of raising and lowering the intermediate molding object is repeated.

[0003]

The above-mentioned method has achieved remarkable results in terms of continuous automatic drivability, but the ultraviolet ray laser is expensive and has a short life, so that the apparatus itself and the operating cost are high. The resin is harmful and difficult to handle, the residual stress remains because it is difficult to obtain accuracy because the ultraviolet curing resin shrinks during curing, and a huge amount of time proportional to the area is required when modeling a cross section with a thick wall. I have a problem.

[0004]

According to the present invention, in a molding space maintained at a temperature below the freezing point, water droplets are selectively discharged to a molding intermediate object placed on a supporting table while the nozzle or the supporting table is moved in parallel to freeze the adhered water droplets. This is a method of growing a modeling intermediate by repeating the process of repeating the process of forming a slice that is firmly integrated with the modeling intermediate and then opening the distance between the support and the nozzle by the slice thickness. .

Even if the ice is thin, it has sufficient strength as long as it can be handled in a temperature environment below the freezing point, and since the viscosity of the water droplets is low, it freezes in close contact with the adhering molding intermediate product and freezes inside. It is possible to create a three-dimensional object excellent in accuracy and strength.

In order to prevent clogging caused by freezing of a nozzle operating in a molding space having a temperature below the freezing point, it is necessary to heat the nozzle with a heater or the like and cover the periphery with a heat insulating material so that hot water is discharged. Good. At this time, the attached water droplets cause the surface layer of the intermediate molding object to change from liquid to solid in the depth direction with an inclination due to the heat capacity of the water droplets, and as a result, the adhered water droplets and the intermediate molding object are completely integrated. This results in simultaneous refreezing, which is very effective in increasing the bond strength between the adhered water droplets and the molding intermediate.

As a method of maintaining the temperature below the freezing point in the modeling space, an electric refrigerator system comprising a compression / volatilization cycle of a refrigerant is preferable, but simply a cooling substance such as dry ice that volatilizes at a temperature below the freezing point is used. It may be arranged in the space. At the same time, a dehumidifying device and defrosting device are installed side by side to prevent mechanical frost and ice from sticking to mechanical devices such as intermediate molding objects, nozzle operation mechanism and support platform lifting mechanism, and the molding space is saved to save cooling energy. It goes without saying that it must have a heat insulating structure. In principle, the temperature of the molding space should be below the freezing point, but if it is too low, the water droplets will freeze before they come into close contact with the intermediate molding object, depending on the initial discharge temperature and the droplet size. Not preferable. Considering this, the temperature is 0
A temperature of about -30 ° C is suitable.

Since the present invention uses the ideal ink of water that does not contain any dissolved or dispersed substance, there is no problem of nozzle clogging and it is possible to reduce the opening cross-sectional area of the nozzle from the aspect of ink preparation. There are no restrictions. In some cases, water drops are colored with water-soluble dyes such as direct dyes and acid dyes, which have excellent compatibility with water, and by using different colors with multiple nozzles, the surface is colored in any pattern. You can easily create things.

Regarding the discharge method, the on-demand type is preferable because the response frequency per nozzle is low, but the speed can be increased by using multiple nozzles, and the structure can be simplified when incorporated in the apparatus. Any method such as a method usually used in an inkjet printer can be selected. The response frequency is about 3,000 to 10,000 in the piezo drive system, and about 40,000 to 50,000 in the bubble jet system.

As in the case of an ink jet printer, the nozzle sweeps a plane in a main scanning / sub-scanning procedure, so-called raster scanning. Therefore, the shaping speed is mainly the sweep area velocity regardless of the cross-sectional shape or the cross-section clogging. Depends on. For this reason, as in the case of the optical molding method, in the case of a case having a thick cross section, only the outer shell is molded, and instead of molding the entire solid, only the honeycomb structure is molded to reinforce the outer shell, which is a heavy burden on software. There is no need to devise.

In an experiment, a bubble jet printer head having 32 nozzles having a square opening with a side of 0.03 mm and a response frequency of 50,000 was used.
Calculate the sweep area velocity for a m x 300 mm build plane. Since a width of 0.96 mm (32 x 0.03 mm) can operate at 1,500 mm (0.03 mm x 50,000) per second, it is possible to move 0.2 mm to operate in the main scanning direction of 300 mm.
If the nozzle switching time in the sub-scanning direction is negligible, it takes 62 seconds ((300 mm / 0.9 mm) to operate 300 mm in the sub-scanning direction.
6 mm) × 0.2) required. If there is no volume expansion of the water droplets discharged from the nozzle, it can be assumed that the water droplets are averaged and frozen in the same shape and volume.
620,000 seconds ((300 mm / 0.03 mm) x 6 for growing a 300 mm x 300 mm modeling plane by 300 mm
2 papers), that is, 172 hours.

As can be seen from this calculation procedure, the molding speed is proportional to the cube of the nozzle diameter and proportional to the response frequency to the first power. Therefore, in the above calculation, one side of the nozzle is tripled 0.09 mm, and the response frequency is Assuming a piezo drive system of 1/5 of 10,000, the required time is 31 hours (1
72 hours x 5 / (3 x 3 x 3)).

In the case of the three-dimensional molding of the ultraviolet curable resin by the stereolithography method, it is considered that the stacking step for each slice is unavoidable, and in order to reduce it, the slice thickness is reduced even though it takes voxel data preparation time and equipment operation time. Although thinning and post-polishing work are performed, according to the present invention, a method of leaving a completed three-dimensional object in the same posture for a while in an environment above the freezing point or 90 ° for more accurate finishing By laying it sideways and rotating it on the horizontal axis for a while in an environment above the freezing point, the convex portion of the step receives relatively more heat from the outside air than the concave portion, so the dissolution speed is faster, and the water dissolved from the convex portion of the step is closer. The surface of the three-dimensional object can be easily smoothed by refreezing. More simply, a method of stroking by hand may be used.
Utilizing this is convenient because it is possible to easily create a three-dimensional object having a smooth surface without stacking steps even with rough voxel data.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an example of a conceptual sectional view for carrying out the present invention. Reference numeral 1 is a heat insulating structure case for housing the apparatus, 2 is a modeling space which is maintained at a temperature below freezing point, 3 is a main scanning moving rail along which a nozzle 5 can move in the main scanning direction, 4a and 4b are heat insulating structure case 1 A sub-scanning moving rail fixed to the upper part of the facing wall surface, along which the main-scanning moving rail 3 can move, 5 is a nozzle for ejecting water droplets, 6 is a support for placing a modeling intermediate, and 7 is a support for each slice thickness unit. A support stand elevating shaft capable of ascending and descending 6, an intermediate molding object 8, and a water droplet 9 attached to the intermediate molding object 8.

[0015]

EFFECTS OF THE INVENTION According to the present invention, the precision and strength are extremely excellent, the equipment cost can be reduced by one digit or more compared with the conventional equipment, and the operating cost is almost only the cooling energy cost. The modeling method of becomes possible. The three-dimensional object according to the present invention can be used as a prototype model as it is for practical use in design evaluation, and can be stored and stored.
Transport can also be handled by using a cooling case. In addition, if necessary, a female mold can be created using silicon rubber, gypsum, clay, etc. for the master model, and easily transferred to various metal / resin materials for industrial production.

[Brief description of drawings]

FIG. 1 is an example of a conceptual cross-sectional view for carrying out the present invention.

[Explanation of symbols]

 1: Heat insulation structure case 2: Modeling space 3: Main scanning moving rail 4a: Sub scanning moving rail 4b: Sub scanning moving rail 5: Nozzle 6: Support stand 7: Support stand lifting shaft 8: Modeling intermediate product 9: Water droplet

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[Procedure amendment]

[Submission date] January 25, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of Invention] Three-dimensional shape forming method

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modeling a three-dimensional object which can be used as a prototype model or a master model based on voxel data output from a three-dimensional model built in a computer or a CT scanner.

[0002]

2. Description of the Related Art A stereolithography method is known as a conventional three-dimensional shaping method. This is because the UV laser device that can freely move the liquid surface of the UV curable resin along the liquid surface in the XY direction is used to selectively irradiate the laser to cure the resin on the surface of the liquid surface to form horizontal slices. Only the process of raising and lowering the intermediate molding object is repeated.

[0003]

The above-mentioned method has achieved remarkable results in terms of continuous automatic drivability, but the ultraviolet ray laser is expensive and has a short life, so that the apparatus itself and the operating cost are high. The resin is harmful and difficult to handle, the residual stress remains because it is difficult to obtain accuracy because the ultraviolet curing resin shrinks during curing, and a huge amount of time proportional to the area is required when modeling a cross section with a thick wall. I have a problem.

[0004]

According to the present invention, in the modeling space maintained at a temperature below the freezing point of the ink, the intermediate modeling object placed on the support is
The nozzle or support base is moved in parallel while the ink is selectively ejected, and the work of solidifying the adhered ink is repeated to form a slice that is firmly integrated with the intermediate molding object. This is a method of growing a modeling intermediate by repeating the process of opening the slice thickness.

Hereinafter, description will be made on the premise of an ink containing water as a main component. Even if water is solidified, that is frozen, even if it is thin, it has sufficient strength as long as it can be handled in a temperature environment below the freezing point. It is possible to create a three-dimensional object having no bubbles and excellent in accuracy and strength. By the way, the hardness of ice is 1.5 at 0 ℃ and 3 at -30 ℃.
(Calcite) to 4 (fluorite).

In order to prevent clogging due to freezing of a nozzle operating in a molding space having a temperature below the freezing point, the nozzle is heated by a heater or the like, and its surroundings are covered with a heat insulating material so that hot water or hot water is discharged. You can do this. At this time, the attached water droplets cause the surface layer of the intermediate molding object to change from liquid to solid in the depth direction with an inclination due to the heat capacity of the water droplets, and as a result, the adhered water droplets and the intermediate molding object are completely integrated. Will result in simultaneous refreezing,
It is very effective in increasing the bond strength between the adhered water droplets and the intermediate product.

As a method for maintaining the temperature below the freezing point in the molding space, an electric refrigerator system comprising a refrigerant compression / vaporization cycle is preferable, but it is possible to directly vaporize the solid directly and cool the object without humidity. Alternatively, dry ice (sublimation point −78.50 ° C.) having a large latent heat may be arranged in the space. Needless to say, the modeling space needs to have a heat insulating structure in order to save cooling energy. Further, if necessary, a dehumidifying device may be provided to prevent mechanical frost from sticking to mechanical devices such as a molding intermediate product, a nozzle operating mechanism and a support platform elevating mechanism. In principle, the temperature of the molding space should be below the freezing point, but if it is too low, the water droplets will freeze before they come into close contact with the intermediate molding object, depending on the initial discharge temperature and the droplet size. Not preferable.

Since the present invention uses the ideal ink of water that does not contain any dissolved or dispersed substance, there is no problem of nozzle clogging and it is possible to reduce the opening cross-sectional area of the nozzle from the aspect of ink preparation. There are no restrictions. In some cases, water droplets are colored with a dye or pigment dispersion that has excellent compatibility with water, such as direct dyes and acid dyes, and by using different colors with multiple nozzles, the surface is colored in any pattern. A shaped object can be easily created.

Regarding the discharge method, the on-demand type is preferable because the response frequency per nozzle is low, but the speed can be increased by using multiple nozzles, and the structure can be simplified when it is incorporated into the apparatus. Any method such as a method usually used in an inkjet printer can be selected. Incidentally, the response frequency is 3,000 to 10,000.

As in the case of an ink jet printer, the nozzle sweeps a plane in a main scanning / sub-scanning procedure, so-called raster scanning. Therefore, the shaping speed is mainly the sweep area velocity regardless of the cross-sectional shape or the cross-section clogging. Depends on. For this reason, as in the case of the optical molding method, in the case of a case having a thick cross section, only the outer shell is molded, and instead of molding the entire solid, only the honeycomb structure is molded to reinforce the outer shell, which is a heavy burden on software. There is no need to devise.

In an attempt, a bubble jet printer head having 400 multi-nozzles having a square opening with a side of 0.025 mm and a response frequency of 5,000 was used.
The modeling speed in the case of a modeling space of 300 mm × 300 mm × 300 mm is calculated. However, it is assumed that the nozzle openings of the multi-nozzle are connected without a gap. 10m
125 mm per second with a width of m (400 x 0.025 mm)
(0.025mm x 5,000) Since it can operate, 30
It takes 2.4 seconds (300 mm to move in the 0 mm main scanning direction).
/ 125 mm), and if the nozzle switching time in the sub-scanning direction is negligible, it takes 72 sheets ((300 mm / 10 mm) × 2.4) to operate 300 mm in the sub-scanning direction. If the water droplets ejected from the nozzle have no volume expansion, it can be assumed that they are averaged and frozen in the same shape and volume. Eventually, a plane of 300 mm × 300 mm is grown to a height of 300 mm by 864, 000 seconds ((300 mm / 0.025 mm) × 72 seconds), that is, 240 hours are required. In the above calculation, a multi-nozzle (1
2,000 pieces), the required time is 0.02
One line of 5 mm is 0.0002 seconds (1/5000), so it takes 2.4 seconds to move 300 mm in the sub-scanning direction ((300 mm / 0.025 mm) x 0.0002 seconds).
28,800 to grow to a height of 300 mm
Seconds ((300 mm / 0.025 mm) × 2.4 seconds), that is, 1 / 30th of the previous case, is required for 8 hours.

As can be seen from the above calculation procedure, the molding speed is proportional to the cube of the nozzle diameter, and is proportional to the response frequency and the cube of the number of mounted nozzles.
Assuming that one side of the nozzle is four times as large as 0.1 mm, the required time is 1/64 (1 / (4 × 4 × 4)).

In the case of the three-dimensional molding of the UV curable resin by the stereolithography method, it is inevitable that the stacking step for each slice is unavoidable. However, according to the present invention, a method of leaving a completed three-dimensional object in the posture as it is for a while in an environment above the freezing point, or for more accurate finishing is 90 ° By laying it sideways and rotating it on the horizontal axis for a while in an environment above the freezing point, since the convex portion of the step receives relatively more heat from the outside air than the concave portion, the dissolution speed is faster, and the water dissolved from the convex portion of the step is The surface of the three-dimensional object can be easily smoothed by re-freezing because it spreads in the adjacent concave portion. More simply, a method of stroking by hand may be used.
Utilizing this is convenient because it is possible to easily create a three-dimensional object having a smooth surface without stacking steps even with rough voxel data.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an example of a conceptual sectional view for carrying out the present invention. Reference numeral 1 is a heat insulating structure case for housing the apparatus, 2 is a modeling space which is maintained at a temperature below freezing point, 3 is a main scanning moving rail along which a nozzle 5 can move in the main scanning direction, 4a and 4b are heat insulating structure case 1 A sub-scanning moving rail fixed to the upper part of the facing wall surface, along which the main-scanning moving rail 3 can move, 5 is a nozzle for ejecting water droplets, 6 is a support for placing a modeling intermediate, and 7 is a support for each slice thickness unit. A support stand elevating shaft capable of ascending and descending 6, an intermediate molding object 8, and a water droplet 9 attached to the intermediate molding object 8.

[0015]

EFFECTS OF THE INVENTION According to the present invention, the precision and strength are extremely excellent, the equipment cost can be reduced by one digit or more compared with the conventional equipment, and the operating cost is almost only the cooling energy cost. The modeling method of becomes possible. The three-dimensional object according to the present invention can be used as a prototype model as it is for practical use in design evaluation, and can be stored and stored.
Transport can also be handled by using a cooling case. In addition, if necessary, a female mold can be created using silicon rubber, gypsum, clay, etc. for the master model, and easily transferred to various metal / wood Hh materials for industrial production.

[Brief description of drawings]

FIG. 1 is an example of a conceptual cross-sectional view for carrying out the present invention.

[Explanation of reference numerals] 1: Heat insulating structure case 2: Modeling space 3: Main scanning movement rail 4a: Sub scanning movement rail 4b: Sub scanning movement rail 5: Nozzle 6: Support stand 7: Support stand lift shaft 8: Modeling intermediate 9: Water drop

Claims (3)

[Claims] 1. In a modeling space maintained at a temperature below the freezing point, water droplets are selectively discharged to a molding intermediate object placed on a supporting table while moving a nozzle or the supporting table in parallel, and the adhering water droplets are frozen. A three-dimensional shape forming method characterized by repeating the work of shaving. 2. The three-dimensional modeling method according to claim 1, wherein the water droplets are hot water heated to room temperature or higher. 3. The three-dimensional shaping method according to claim 1, wherein the water droplets are colored.