JP2000326052A - Three-dimensional article manufacturing method and three-dimensional article manufacturing apparatus - Google Patents

Abstract

(57) [Problem] To provide a three-dimensional article manufacturing method and a three-dimensional article manufacturing apparatus capable of quickly and easily manufacturing a three-dimensional article having high strength and rigidity, excellent accuracy, and surface roughness by utilizing rapid prototyping. I do. SOLUTION: A mold manufacturing process P1 for forming a mold from a thermoplastic material, and an easy fusion metal which is melted at a temperature lower than the softening point of the thermoplastic material is poured into the mold and solidified to form a cast product. A three-dimensional product manufacturing method, comprising: a gold casting process P2; and a mold removing process P3 of dividing and removing the mold and removing the cast product as a target three-dimensional product. No special heating and melting equipment is required, a mold can be easily created in a design office or the like, and a plurality of three-dimensional products can be manufactured using the single mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a three-dimensional article such as a part, a product, and a model, and more particularly to a method and an apparatus for manufacturing a three-dimensional article requiring high strength and rigidity.

[0002]

2. Description of the Related Art Rapid prototyping (RP) is a technique for rapidly and easily realizing computer stereoscopic data.
That. A photolithography method in which a liquid synthetic resin is exposed to cause a photochemical reaction to partially solidify it, and a selective laser sintering method (SLS method) in which powder is irradiated with a laser beam to partially solidify it Is well known. The details of rapid prototyping are described in, for example, Takeshi Nakagawa and Yoji Marutani, "Additive Manufacturing System" (Industry Research Council).

[0003] Generally, in rapid prototyping,
Since many thin layers having a thickness of 10 μm to 1 mm are stacked and formed, a complicated shape can be created without changing the process. Taking advantage of this feature, for example, if rapid prototyping is introduced into design work such as optimizing the shape of parts while repeating experiments, experimental models can be manufactured at low cost at any time from 3D CAD data. become. That is, it is possible to shift the design work to a form centered on three-dimensional CAD, and achieve so-called concurrent.

[0004] Further, it is also possible to entrust a user to design a product and realize a custom design production for increasing the added value of the product by one-piece production according to demand.

However, conventional materials for rapid prototyping do not always have high strength and rigidity enough to withstand use as a product housing or an experimental model.

[0006] In order to solve these problems, there is a method of post-processing a molded article and replacing a resin material for rapid prototyping with metal. Often used is vanishing model casting
(Investment casting). In this method, a molded article made by rapid prototyping is buried in molding sand, and molten metal is poured from above. Then
The heat decomposes the shaped object into a gas or melts and soaks into the sand, and the shape of the shaped object is directly replaced by metal.

[0007] Japanese Patent Application Laid-Open No. 7-195141 discloses that a model is manufactured by stereolithography, the model is immersed in a slurry of ceramic, and then refractory particles are sprinkled. Shows how to make it.

Further, a metal powder such as stainless steel is used for SLS.
There is also used a method of shaping as a material of the method and finishing by infiltrating copper or the like or impregnating the resin with the material.

According to these methods, it is possible to produce a molded article having higher strength and rigidity than a molded article made of only a resin material.

[0010] Japanese Patent Application Laid-Open No. H10-156514 discloses a method in which a three-dimensional body is formed by a stereolithography apparatus using a metal powder or the like having a surface coated with a thermoplastic resin as a raw material, and sand is applied thereto to form a shell. Shows a method of impregnating a three-dimensionally shaped body by bringing a molten metal into contact therewith.

[0011]

The above prior arts require large-scale equipment for post-processing. In the vanishing model casting method, equipment for heating and melting the metal to a temperature of 600 ° C. or higher is required. In addition, the SLS method using metal powder requires equipment for infiltration for keeping the molded article at a high temperature for a long time, and pressurizing and depressurizing equipment for infiltrating the molded article with resin.

[0012] These facilities also require considerable skill to operate. It is conceivable to use equipment owned by other companies, but in such a case, it takes time to logistics, and the simplicity and quickness, which are features of rapid prototyping, are impaired.

[0013] Further, in the above-mentioned prior art, the precision and the surface roughness of the formed article are inferior. Therefore, when a shaped article having a smooth surface or a shaped article with high precision is required, a large amount of labor and time are required for finishing, and there is still a problem in terms of simplicity and quickness.

An object of the present invention is to provide a three-dimensional article manufacturing method and a three-dimensional article manufacturing apparatus capable of quickly and easily manufacturing a three-dimensional article having high strength and rigidity, excellent accuracy, and surface roughness by utilizing rapid prototyping. It is to be.

[0015]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a mold manufacturing process for forming a mold from a thermoplastic material, and a method for easily melting the mold at a temperature lower than the softening point of the thermoplastic material. The present invention proposes a method of manufacturing a three-dimensional product including an easy-fusion gold casting process in which gold is poured into a mold and solidified to form a cast product, and a mold removing process in which the mold is divided and removed to take out the cast product as a target three-dimensional product. In this way, a mold is made of a thermoplastic material, and the fusible alloy melted at a temperature lower than the softening point of the thermoplastic material is poured into the mold and solidified into a cast product, utilizing rapid prototyping. A three-dimensional product having excellent accuracy and surface roughness as well as strength and rigidity can be manufactured quickly and easily.

[0016] The thermoplastic material is a resin material or a resin composite material. In the mold manufacturing process, the thermoplastic material powder is partially sintered to form a thin layer, and the thin layers are stacked to form the mold. A selective laser sintering (SLS) shaping process may be included. In this case, a three-dimensional product having a complicated three-dimensional shape can be manufactured using a commercially available modeling device without complicating the process.

When the thermoplastic material is a composite material containing a resin and inorganic material beads, deformation of a mold which occurs at the time of casting can be suppressed, and a three-dimensional product with high accuracy can be manufactured. If the thickness of the mold is reduced, the time required to cool the mold into which the easily fused metal is cast is reduced, and in that sense, a three-dimensional product can be manufactured quickly.

The thermal conductivity of the inorganic material beads is desirably higher than the thermal conductivity of the resin. This is because the time required to cool the mold into which the easily fused metal is cast can be reduced, and a three-dimensional product can be manufactured more quickly.

In any of the three-dimensional article manufacturing methods, the mold manufacturing step may include a mold smoothing step for smoothing the surface of the mold. Since the surface of the mold only needs to be smoothed only once, the trouble of smoothing the surfaces of a plurality of three-dimensional articles having the same shape can be omitted, and a large number of three-dimensional articles having a smooth surface can be manufactured quickly and easily.

[0020] The mold removing step may include a casting smoothing step for smoothing the surface of the casting. In general, concave portions that are difficult to reach in the mold smoothing process become convex portions in the casting smoothing process, so that a three-dimensional product having a smooth surface can be manufactured quickly and easily.

The mold manufacturing step includes a step of forming a flow path for heat exchange inside the mold.
A mold cooling step of cooling a mold by circulating a cooling fluid through the flow path may be included. In this method, the time required to cool the mold into which the easy-fusion alloy is cast is reduced, the material properties of the easy-fusion alloy are improved, and a three-dimensional article having high strength and less likely to be deformed by creep can be quickly manufactured.

The easy fusion casting step may include a step of placing a reinforcing material in the mold before pouring the easy fusion metal into the mold, so that a three-dimensional article having high strength and rigidity can be manufactured.

[0023] The mold manufacturing step includes a step of forming a flow path for heat exchange inside the mold, and the easy-fusion gold casting step heats the mold by circulating a heating fluid through the flow path. A mold heating step can also be included. Defects caused by the non-uniform solidification of the easy fusion metal in contact with the reinforcing material at room temperature can be avoided, and a three-dimensional product having high strength and rigidity can be reliably manufactured.

If a small metal piece having a higher melting point than that of the easy-fusion metal is used as the reinforcing material, a three-dimensional product having higher strength and rigidity can be manufactured.

In the case where the method includes a reinforcing material forming step of partially sintering a metal powder having a melting point higher than that of the easy-fusion metal to form a thin layer and stacking the thin layers to form the reinforcing material, the reinforcing material with respect to the volume of the mold is included. , And a three-dimensional article having particularly high strength and rigidity can be manufactured.

By including a reinforcing material infiltration step of infiltrating a metal into the porous reinforcing material, a three-dimensional article having particularly high strength and rigidity can be manufactured quickly and easily by utilizing a commercially available molding apparatus. it can.

If the mold removing step includes a step of applying a shock or vibration to the mold to separate the mold and the casting, the three-dimensional article stuck in the mold can be easily taken out, and has a complicated and fragile shape. Three-dimensional products can be manufactured simply and reliably.

An offset mold shape creating step of offsetting all or a part of the shape of the target three-dimensional article to create a mold shape suppresses deformation of the mold during casting,
Highly accurate three-dimensional products can be manufactured.

A mold shape designing apparatus provided with an offset mold making means for offsetting all or a part of the shape of the target three-dimensional article to the outside and creating the outer shape of the mold, or
For fixing the mold to a mold shape design device provided with a mold matching shape creating means for creating a partial shape for aligning the divided molds with each other, or a holder for suppressing deformation of the mold. The use of a mold shape design device provided with a retainer fixed shape creating means for creating the partial shape of the above makes it possible to quickly and easily manufacture a high-precision three-dimensional product while saving the trouble of shape manipulation.

If a flow path forming means for adding the shape of the flow path to the shape of the mold is provided, a three-dimensional article having high strength and rigidity can be manufactured quickly and reliably without labor for shape operation.

In the case where the reinforcing member shape creating means for creating the shape of the reinforcing member based on the target shape of the three-dimensional article is provided, a three-dimensional article having particularly high strength and rigidity can be manufactured while saving the trouble of the shape operation. .

If a temperature controller is used to keep the molten fusible alloy at a temperature 5 ° C. to 20 ° C. lower than the softening point of the thermoplastic material, the temperature of the fusible alloy is adjusted so that the mold is not deformed by casting. It is possible to easily and safely produce a three-dimensional product without the need for melting.

[0033] If a temperature controller for keeping the heating fluid at a temperature lower than the softening point of the thermoplastic material and higher than the melting point of the fusible alloy, and a pump for discharging the heating fluid to the flow path are provided. In addition, the need for preparing and flowing a liquid for preheating the mold on which the reinforcing material is placed can be eliminated, and a three-dimensional product having high strength and rigidity can be easily and reliably manufactured.

If the heating fluid is a polyhydric alcohol or a mixture containing a polyhydric alcohol as a main component, the liquid for preheating the mold does not cause environmental pollution, and a three-dimensional product having high strength and rigidity can be obtained. Safe, simple and reliable production.

A temperature controller for maintaining the heating fluid at a temperature lower than the softening point of the thermoplastic material and higher than the melting point of the fusible alloy; and supplying the heating fluid or the cooling fluid to the flow path. A pump for discharging, and a valve for switching the discharge of the heating fluid or the cooling fluid to one of the flow paths, a discharge port of a liquid for preheating the mold, and a cooling port for cooling the mold. This eliminates the need for reconnecting the liquid discharge port, and makes it possible to produce a three-dimensional product with high rigidity safely, simply, reliably, and quickly.

When a small piece of metal coated with easy-fusion gold is employed, the labor for preparing a reinforcing material according to the shape of the three-dimensional article can be omitted, and a three-dimensional article having high rigidity can be manufactured quickly and easily.

When the metal is iron or an iron-based alloy, the affinity between the reinforcing material and the easy-fusion alloy is enhanced, so that a three-dimensional article having high strength and rigidity can be manufactured quickly and easily.

When the ratio of the maximum size to the minimum size of the metal pieces measured along three directions perpendicular to each other is set to be three times or more, the reinforcing material with respect to the volume of the mold is set. Since the filling rate is increased, a three-dimensional article having higher rigidity can be manufactured.

In the case where a screen for separating the reinforcing material from the molten easy-fused metal is provided, the easy-fused metal can be reused, and a three-dimensional article having high strength and rigidity can be manufactured quickly, simply, and at low cost.

In the easy fusion financial solution apparatus which also serves as a heating fluid circulation apparatus, required equipment can be reduced in size and cost, and a three-dimensional product having high strength and rigidity can be manufactured quickly, simply, and at low cost.

In the easy fusion financial solution apparatus also serving as the easy fusion gold recycling apparatus, the required equipment can be reduced in size and cost, and a three-dimensional product having high strength and rigidity can be manufactured quickly, simply, and at low cost.

When an easy-fusion alloy containing bismuth and tin as main components is employed, the easy-fusion alloy is unlikely to cause environmental pollution, and a three-dimensional product having high strength and rigidity can be used safely, simply, and easily.
Can be manufactured reliably.

Further, 0.5% to 5% of copper or 0.5%
When 5% to 5% of silver is contained in the easy-fusion alloy, the material properties of the easy-fusion alloy can be improved, and a three-dimensional product having high strength and rigidity and less likely to be deformed by creep can be manufactured safely, simply, and reliably. .

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, referring to FIGS.
Embodiments of a method and apparatus for manufacturing a three-dimensional article according to the present invention will be described.

<< Embodiment 1 >> FIG. 1 is a flowchart showing a processing procedure of a three-dimensional article manufacturing method P according to the present invention. A three-dimensional product manufacturing method P for manufacturing a completed three-dimensional product M3 from CAD data D describing the shape of a target three-dimensional product includes a mold manufacturing process P1, an easily fused gold casting process P2, and a mold removal process P3. .

The mold manufacturing process P1 is a process of making the mold M1 by the SLS method based on the CAD data D. The easy fusible alloy casting step P2 is a step of pouring molten easy fusible metal into the mold M1, and then cooling and solidifying it. The mold M1 into which the easily fused gold is cast is referred to as a cast mold M2. The mold removing step P3 is a step of removing the mold M1 from the cast mold M2 and leaving a finished three-dimensional product M3 made of easy fusion gold.

FIG. 2 is a flowchart showing a more detailed processing procedure of the mold manufacturing process P1. The data receiving step P11 is a step of receiving CAD data D as a solid model from a connected computer and converting the solid model into surface shape data D1 as a surface model.

The mold shape creating step P12 is a step of offsetting the surface shape data D1 to create the outer shape data D2, and combining these to create mold shape data D3.

To the mold shape data D3, a partial shape such as a mold division surface T1 necessary for using the modeled object W as the mold M1 is also added.

The SLS molding step P13 is a step of manufacturing a mold M1 having a shape described by the mold shape data D3 by the SLS method.

FIG. 3 is a view showing the structure of the SLS molding apparatus A used in the SLS molding step P13. The SLS modeling apparatus A includes a container A1 for holding the material powder S, a recoater A2 for flattening the surface of the material powder S, and a feed screw A8.
Recoater driving device A that reciprocates recoater A2 by turning
3, a laser head A4 for irradiating the surface of the material powder S with a laser beam, a scanner A5 for scanning the laser head A4 back and forth, right and left, an elevator A6 for placing and supporting the material powder S and the object W, and an elevator A6. And a control device A9 that controls the operation of the SLS modeling apparatus A as a whole.

The recoater driving signal X1 is a signal for operating the recoater driving device A3 and supplying electric power. The scanner and laser drive signal X2 is a signal for controlling the scanning path of the laser head A4 and blinking of the laser beam and supplying power. The elevator drive signal X3 is a signal that controls the operation of the elevator A6 and supplies power.

FIG. 4 is a diagram showing the operation of the SLS modeling apparatus A of FIG. The SLS modeling apparatus A irradiates the surface of the flattened material powder S with a laser beam while scanning the material powder S, sinters the material powder S, and has the cross-sectional shape of the modeled object W described by the mold shape data D3. Make layers. Then, a plurality of layers are stacked to create a modeled object W having a target three-dimensional shape.

Upon receiving the mold shape data D3, the control device A9 generates three-dimensional data having a three-dimensional shape of the modeled object W based on the data D3. Next, for lamination,
The intersection of this three-dimensional data with the horizontal plane at the height of each layer is calculated, the cross-sectional shape of the modeled object W is calculated, and for each layer, a recoater drive signal X1, a scanner, a laser drive signal X2, an elevator drive signal X3 Is automatically generated.

The SLS modeling apparatus A causes the material powder S to be placed on the elevator A6 or the modeled object W by these drive signals.
And reciprocate the recoater A2 to flatten the surface of the material powder S. The surface of the material powder S is irradiated with a laser beam from the laser head A4.

The scanner A5 scans the laser head A4 along the cross section of the object W. The material powder S is sintered by the laser beam to form a thin layer.

The elevator A6 is lowered by the thickness of one layer, and preparations are made for stacking a new layer on the model W.

By such an operation, finally, the mold M1
Is made.

The commercially available SLS molding apparatus A uses nylon powder as the material powder S. Nylon, which is a polymer having high crystallinity, has a sharp softening point which can be regarded as a melting point, and its temperature is about 190 ° C. Since this softening point temperature is sufficiently higher than the melting point of the easy-fusion alloy which is 160 ° C. or less, it can be used as a mold for casting the easy-fusion alloy as a molded article W.

FIG. 5 is a flow chart showing a method for realizing the easy fusion gold casting process P2. Mold cleaning process P
Reference numeral 21 denotes a step of removing the material powder S remaining inside the mold M1 and the material powder S adhering to the mold M1 to produce a cleaned mold M11.

The mold smoothing step P22 is a step of smoothing a step appearing on the surface of the cleaned mold M11 by polishing or painting when the mold M1 is manufactured by lamination.

The easy-fused gold melting step P23 is a step of heating and melting the easily-fused gold F so as not to exceed the melting point of the material of the mold M1, thereby providing the easily-fused gold melt F1.

FIG. 6 is a chart showing an example of the composition of the easy fusion metal F that can be used. Among these easy-fusion alloys F, those containing cadmium and lead are difficult to use, and therefore, a practical material is bismuth or tin eutectic alloy having a melting point of 138 ° C. Since the melting point of the fusible alloy F is low, a large-scale casting facility is unnecessary. The easy-fusion-gold casting step P24 is a step of casting the easy-fusion gold melt F1 into the cleaned mold M11 to produce an unsolidified mold M12.

In the easy fusion gold cooling step P25, the unsolidified mold M
This is a step of cooling the molten metal 12 and solidifying the cast easily fused gold melt F1 to produce a cast mold M2.

FIG. 7 is a view showing a mold removing step P3. The casting smoothing step P33 is a step of smoothing the surface of the casting M21 by polishing or painting to obtain a finished three-dimensional product M3.

In the mold dividing step P31, the mold M1 surrounding the cast mold M2 is divided at the mold dividing plane, and the casting M
This is the step of taking out 21.

The die removing step P32 is a step of removing the divided mold M1 from the casting M21 stuck in the mold M1. Depending on the shape of the casting M21 and the mold dividing surface T1, the mold M1 may not easily come off from the casting M21. In such a case, in addition to the mold setting process P31,
A die cutting process P32 is required.

According to the three-dimensional article manufacturing method P, a completed three-dimensional article M3 made of the easy fusion metal F is produced. The strength of the fusible alloy F represented by the tensile strength is about 60 MPa, and the rigidity represented by the Young's modulus is about 30 GPa.
When these values are compared with nylon used in a commercially available SLS molding apparatus, the strength is about 3 times and the rigidity is about 15 times.

The finished three-dimensional product M3 made of the easy fusion metal F can be easily polished and smoothed by painting. In addition, the three-dimensional article manufacturing method P does not include a step that requires extensive equipment. Therefore, when the three-dimensional article manufacturing method P is used, a three-dimensional article having not only high strength and rigidity but also excellent accuracy and surface roughness can be quickly and easily manufactured by utilizing rapid prototyping.

Next, the three-dimensional article manufacturing method P will be described in detail with reference to examples. In this example, an ornament used as an interior is made. The three-dimensional cedar shape is described by CAD data D prepared in advance.

In the data receiving step P11, the CAD data D is converted into a surface model to convert the surface shape data D1.
make. FIG. 8A is a diagram schematically illustrating the surface shape R1 described by the surface shape data D1.

In the mold shape forming step P12, the surface shape data D1 is offset to the outside and the outer shape data D2 is offset.
make. FIG. 8B is a diagram schematically illustrating the outer shape R2 described by the outer shape data D2. Further, the surface shape R1 is subtracted from the external shape R2 to form a shell shape having a substantially uniform thickness. If the thickness of the mold M1 is made uniform, deformation of the mold M1 caused by a temperature change during casting can be minimized.

The shell shape thus formed is added with various partial shapes necessary for using the modeled object W as the mold M1 to form a mold shape R3. The partial shape includes a mold dividing surface T1 for dividing the mold M1 into a plurality of pieces, a bit pin T2 for aligning the position of the mold M1, a support leg T3 for holding the mold M1 vertically, and a fusion of the metal to the mold M1. A gate T4 for pouring the object F1 and an air vent T5 for replacing the air in the mold M1 with the fusible gold melt F1.
A clipping point T6 for assembling the divided mold M1 with a clip metal fitting; a fixing leg T7 for attaching to the fixing metal fitting for suppressing deformation of the mold M1; a flow path T8 for flowing a liquid for heating or cooling the mold M1; Is included. FIG. 8C is a diagram showing the template shape R3 described by the template shape R3 data.

The shape operation for forming the mold shape R from the CAD data D is usually performed manually by a CAD operator. To support this, Modeler C is prepared as dedicated CAD software. The modeler C automatically or extremely performs an operation of offsetting the surface shape R1 to form the external shape data D2 and the shell shape, an operation of determining the mold division surface T1, an operation of adding various partial shapes to the shell shape, and the like. It has commands for easy operation.

FIG. 9 is a diagram showing an example of the screen of the modeler C. The commands of the modeler C are registered in the menu C1, and the CAD operator can execute a complicated shape operation by a simple operation using these commands. For example, the “outer shape” command is a command for generating a new three-dimensional shape by offsetting the selected three-dimensional shape outward.

Therefore, if the “outer shape” command is executed after selecting the surface shape R1, the outer shape R2 can be easily created. Further, if the “shell shape” command is executed after selecting the outer shape R2 and the surface shape R1, the shape can be easily formed. Further, as shown in the illustrated screen, a reference point Q is set on the surface of the shell shape, and then a “gate” command is executed, thereby adding the gate T4.

In the SLS molding process P13, a commercially available SLS
The mold shape data D3 is transmitted to the molding apparatus A, and the mold shape R
A model W having a three-dimensional shape is formed, that is, a mold M1.

In the mold cleaning step P21, the mold M
1 is turned upside down and vibrated to drop the material powder S clogging the inside of the mold M1. The material powder S attached to the inner surface of the mold M1 inserts a thin rubber tube into the mold M1,
Air is blown out from the end face to remove it. Thus, the cleaned mold M11 is produced.

In the mold smoothing step P22, the inner surface of the cleaned mold M11 is smoothed to a predetermined surface roughness. As a method of smoothing, there are a polishing method of removing a convex portion of a step using a paper file or the like, a coating method of filling a concave portion of the step with a filling paint, and a method of using both.

In the easy fusion gold dissolving step P23, the easy fusion gold F
It is convenient to use a dedicated electric furnace H in order to melt and maintain the temperature at an appropriate temperature.

FIG. 10 is a diagram showing the structure of the electric furnace H. The crucible H1 contains a bismuth and tin eutectic alloy having a melting point of 138 ° C., and is melted by the heat generated by the heater H3 to form a fusible gold melt F1. When the fusible gold melt F1 is overheated, it is easily oxidized by oxygen in the air. Therefore, the crucible H1 is indirectly heated using the glycerin bath H2 to prevent overheating of the fusible gold melt F1.

The glycerin bath H2 is provided with a thermostat H4 for controlling energization of the heater H3. When the temperature of glycerin exceeds a predetermined set temperature due to the heat generated by the heater H3, the thermostat H4 operates to activate the heater H3.
Turn off the power to 3. The temperature of the glycerin bath H2 and the fusible gold melt F1 is kept at the set temperature of the thermostat H4. The optimum set temperature of the thermostat H4 is determined by the mold M
It depends on the material. Usually, the temperature is set at 5 ° C. to 20 ° C. lower than the softening point. Instead of glycerin, a polyhydric alcohol such as ethylene glycol may be used.

When nylon is used as the material powder S, the set temperature may be set to 185 ° C., considering that its softening point is about 190 ° C. Nylon has a sharp softening point and hardly softens even at 185 ° C.

Note that the pouring outlet H5 of the electric furnace H is connected to the crucible H
1 so as to prevent the oxide floating on the surface of the fusible gold melt F1 from flowing into the mold M1 from the spout H5.

In the easy fusion gold pouring step P24, first, the cleaned mold M11 divided into a plurality is assembled by attaching the clip J3 to the clipping point T6, and further, the support leg T3 is fixed to the base J1. Support vertically. In addition, a fixing leg T7 is attached to a fixing metal fitting J2 attached to the base metal fitting J1 to suppress deformation of the mold M1 due to casting. This is placed so that the gate T4 is located directly below the outlet H5 of the electric furnace H, and the easy fusion metal F is poured from above.

In the easy fusible alloy cooling step P25, the unsolidified mold M12 is allowed to cool for a while to solidify the easy fusible melt F1. FIG. 11 is a view showing the structure of the cast mold M2 thus produced.

In the mold dividing step P31, the cast mold M2
Is inserted into the gap between the molds M1 surrounding the mold M1 and twisted to remove the divided mold M1, thereby taking out the casting M21. When nylon is used as the material of the mold M1, there is no need to use a mold release agent or the like, since the affinity between nylon and the easily fused metal F is very small.

However, depending on the shape of the casting M21 and the mold dividing surface T1, the casting M21 may fit into the divided mold M1 and may be difficult to remove. Punching process P3
In 2, the mold M1 is held so that the cast product M21 that is stuck is on the top, and the portion of the mold M1 around the cast product M21 is hit with a hammer I2. In this case, due to the difference in density between the nylon and the easily fused metal F, the casting M21 comes out of the mold M1.

Nylon, which is a material of the mold M1, is not easily broken by impact or vibration, but slightly elastically deforms when a large force is applied. Therefore, in many cases, using this method, the casting M21 can be separated from the mold M1 without breaking the casting M21. FIG. 12 is a diagram showing operations performed in the die-setting step P31 and the die-cutting step P32.

In the casting smoothing step P33, the surface of the casting M21 is smoothed to a predetermined surface roughness by polishing or painting. Also in the mold smoothing step P22, the inner surface of the mold M1 is smoothed, but it is difficult to sufficiently smooth the recesses of the mold M1 that are hard to reach.

However, since the concave portion of the mold M1 becomes a convex portion of the cast product M21 by casting, the concave portion that could not be sufficiently smoothed in the mold smoothing process P22 is polished or removed in the cast product smoothing process P33. Coating can be performed sufficiently and smoothed. When the mold smoothing step P22 and the casting smoothing step P33 are combined in this way, it is possible to sufficiently smooth the entire surface of the casting M21.

The mold M1 removed in the mold dividing step P31 and the mold removing step P32 can be used repeatedly 10 times or more. This repetitive use is one of the features of the present invention.
One. Therefore, when a plurality of completed three-dimensional objects M3 are produced, as much as possible of the surface of the mold M1 is smoothed in the template smoothing step P22,
Casting leveling process P33
Can be saved.

Example 2 If beads of an inorganic material such as glass are mixed with the material powder S, the strength and rigidity of the mold M1 can be increased and deformation during casting can be suppressed. In addition, the thickness of the mold M1 can be reduced, and heat can be easily radiated. Thereby, in the easy fusion gold cooling step P25, the unsolidified mold M12
Is reduced, and the completed three-dimensional object M3 is obtained more quickly.

Further, if beads made of a material having a high thermal conductivity such as metal are used, the time for cooling the unsolidified mold M12 can be further reduced.

<< Embodiment 3 >> The mold M1 is used in the mold manufacturing process P1.
If a flow path for heat exchange is formed inside the mold M1 when making the unsolidified mold M in the easy-fusion-metal cooling step P25,
For the purpose of speeding up the cooling of the cooling liquid 12, a cooling liquid can be flowed through the flow path. This method can freely control the solidification time of the easily fused gold melt F1, unlike the method of reducing the thickness of the mold M1. Therefore, the casting M having a complicated shape
Even 21 can be made accurately. In addition, since the meltable alloy F1 can be rapidly solidified, the crystal of the meltable alloy F used as the material of the casting M21 becomes finer, and the material properties of the casting M21 are improved.

As a method of further increasing the strength and rigidity of the finished three-dimensional product M3, a method of forming a reinforcing material with a metal having a melting point higher than that of the easy fusion metal F and placing it in the mold M1 in advance before casting. is there. However, in this method, the template M1
When the ratio of the volume of the reinforcing material to the volume of
The cast fusible gold melt F1 is cooled in contact with the reinforcing material at room temperature and solidifies unevenly, so that casting is not performed well.

In order to cope with this, it is effective to preheat the reinforcing material and the mold M1 to a temperature higher than the melting point of the fusible alloy F in advance. Also in this case, if a flow path is formed inside the mold M1, before casting the easily fused gold melt F1,
The mold M1 can be preheated by flowing a heating liquid through the flow path.

In order to support a shape operation for forming a flow path inside the mold M1, a dedicated “flow path” command is registered in the modeler C used in the mold shape creation step P12. This command defines an intermediate surface between the inner surface and the outer surface of the mold M1 such that the ratio of the distance to the inner surface and the distance to the outer surface is constant, and generates a flow path T8 along the intermediate surface. Also, joints are provided at the inlet and outlet of the flow channel T8 so that tubes can be connected.

It is convenient to use a liquid circulating device G to flow a cooling or heating liquid through a flow path formed inside the mold M1.

FIG. 13 is a view showing the structure of the liquid circulation device G. The liquid circulation device G includes a high-temperature glycerin tank G1 for supplying high-temperature glycerin heated by the heater H3.
And a normal temperature glycerin tank G2 for supplying normal temperature glycerin
And both have. Like the electric furnace H, the high-temperature glycerin tank G1 is provided with a heater H3 and a thermostat H4 to keep the temperature of glycerin at about 185 ° C.

The pump G3 discharges high-temperature or normal-temperature glycerin to the discharge port G5. The temperature of the discharged glycerin can be switched by operating the valve G4.
That is, depending on the purpose of using the liquid circulation device G, when pre-heating the mold M1 in the easy-fusion gold casting step P24, high-temperature glycerin is discharged, and the unsolidified mold M12 is cooled in the easy-fusion gold cooling step P25. Switches the valve G4 so that glycerin at normal temperature is discharged. The liquid circulation device G may serve as an electric furnace H.
In this case, the glycerin bath H2 of the electric furnace H is used as the high-temperature glycerin tank G1 of the liquid circulation device G.

There are several ways to make a stiffener that will be placed inside mold M1 before casting.

One method is to prepare a large number of small pieces of steel and coat them with the easy fusion metal F to form a reinforcing material. Iron-based metals such as steel are particularly suitable for use as reinforcing materials because they have a strong affinity for the easy-fusion metal F. This reinforcing material can be prepared in large quantities in advance and used as needed. The reinforcement of small pieces of steel is effective in improving the rigidity of the completed three-dimensional object M3, but the strength is not significantly improved because the reinforcements are not in contact with each other.

When the filling rate of the reinforcing material with respect to the volume of the mold M1 is increased, the rigidity can be further improved. The filling rate of the spherical small pieces is about 50%, but the filling rate can be increased to 70% or more by using flaky or rod-like small pieces and further filling them while vibrating. According to experiments by the inventors, among the dimensions of the metal pieces measured along three mutually orthogonal directions, if the ratio of the largest dimension to the smallest dimension is three times or more, the mold Since the filling rate of the reinforcing material with respect to the volume of the solid is increased, a three-dimensional article having higher rigidity can be manufactured.

Another method is the SLS method using a metal powder such as stainless steel as the material powder S, and is a method of producing a reinforcing material having an optimum shape based on the shape of the completed solid object M3. In the SLS method in which metal powder is used as the material powder S, since the shaped object W is generally made porous, a method of infiltrating a metal such as bronze into this and filling the pores of the shaped object W to increase the strength has already been adopted. Has been put to practical use. With this method,
Since the filling rate of the reinforcing material with respect to the volume of the mold M1 can be increased, the strength and rigidity of the completed three-dimensional object M3 can be greatly improved at the same time. SLS using metal powder as material powder S
Although the method has drawbacks such as a long modeling time and poor accuracy, when the molded article W is used as a reinforcing material in this way, it can be used without any particular problem.

FIG. 14 is a diagram showing an example in which a reinforcing material made by the SLS method is used. The shape of the reinforcing member J4 can be created by offsetting the surface shape R1 inward. That is,
In the mold shape creation process P12, the outer shape R2 and the reinforcing material J1
4 can be made simultaneously.

The unnecessary three-dimensional object M3 is melted,
Easy fusion F can be reproduced. In this case, in order to separate the reinforcing material mixed in the easy fusion metal F, it is convenient to use a dedicated easy fusion metal reproducing device U. FIG. 15 is a diagram illustrating the structure of the easy fusion gold reproducing device U.

The easy fusible metal recycling apparatus U has a screen U1 having many small holes, and separates the easy fusible gold melt F1 from the reinforcing material. The screen U1 is heated by the heater U2 to a temperature equal to or higher than the melting point of the fusible alloy F. When the completed three-dimensional object M3 is placed on the screen U1,
The completed three-dimensional object M3 is melted by the heat transmitted from the screen U1, and is transformed into a fusible alloy melt F1 including a reinforcing material. Of these, only the easy fusion metal F1 falls from the small hole of the screen U1 and is cooled by the water tank U3 to become a solid easy fusion metal F.

[0109] The easy-fusion-metal recycling apparatus U may also be configured to also serve as the electric furnace H. In this case, the crucible H1 of the electric furnace H is placed in place of the water tank U3 of the easy fusion gold recycling device U. FIG. 16 is a diagram showing the structure of the easy-fusion-metal recycling apparatus U configured to also serve as the electric furnace H.

<< Embodiment 4 >> In the mold manufacturing process P1, SL
Instead of using the S molding device A, an optical molding device or FDM
It is also possible to use an additive manufacturing apparatus by another method, such as a modeling apparatus.

For example, in an optical shaping apparatus, shape data in a computer is cut along a horizontal plane at equal intervals in the height direction to create a slice figure. Next, slice figure data is sequentially taken out from the lower end, and a light beam is applied to, for example, a photo-curable resin based on the shape to form a solidified layer. After forming one solidified layer, the base on which the photocurable resin is mounted is lowered relatively, and the uncured resin layers having the same interval are stacked thereon, and this is sequentially turned to the upper end. Repeat the operation. As a result, a desired mold is obtained.

Example 5 A material containing 0.5% to 5% of copper or 0.5% to 5% of silver instead of using a bismuth and tin eutectic alloy as the easy-fusion gold F Can also be used. Preferably, it is a material to which about 2% of copper or silver is added. Bismuth and tin eutectic alloys have the problem that, among practical metallic materials, their strength and rigidity are low, and even with a small force, creep tends to increase in proportion to time, even if the force is small. .

However, when copper or silver is added to the fusible alloy F, the crystal becomes finer, so that strength and rigidity are increased and creep is suppressed. The melting point is somewhat higher, but is not a problem. If the content of copper or silver exceeds 5%, the melting point becomes too high, while if it is less than 0.5%, the melting point becomes too high.
Material properties are not improved.

[0114]

According to the present invention, a mold is made of a thermoplastic material, and the fusible alloy melted at a temperature lower than the softening point of the thermoplastic material is poured into the mold and solidified to form a cast product. Utilizing rapid prototyping, it is possible to quickly and easily manufacture a three-dimensional product having high strength and rigidity, as well as excellent accuracy and surface roughness.

At this time, since no equipment that becomes high temperature is used, a three-dimensional product made of metal can be easily manufactured even in a closed working environment such as a design office.

The mold can be used repeatedly 10 times or more. Therefore, when a plurality of completed three-dimensional objects are to be produced, in the mold smoothing step,
By smoothing as much of the surface of the mold as possible, the casting product smoothing step, which requires the number of completed solid objects, can be saved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure of a three-dimensional item manufacturing method P according to the present invention.

FIG. 2 is a flowchart showing a more detailed processing procedure of a mold manufacturing process P1.

FIG. 3 is a view showing the structure of an SLS modeling apparatus A used in an SLS modeling step P13.

FIG. 4 is a view showing the operation of the SLS modeling apparatus A of FIG.

FIG. 5 is a flowchart showing a method for realizing an easy fusion gold casting process P2.

FIG. 6 is a chart showing an example of a composition of an easy fusion metal F that can be used.

FIG. 7 is a view showing a mold removing step P3.

FIG. 8 is a diagram showing a surface shape R1, an outer shape R2, and a mold shape R3.

FIG. 9 is a diagram illustrating an example of a screen of a modeler C;

FIG. 10 is a view showing the structure of an electric furnace H.

FIG. 11 is a view showing the structure of a completed mold M2.

FIG. 12 is a diagram showing operations performed in a mold dividing step P31 and a die removing step P32.

FIG. 13 is a diagram showing a structure of a liquid circulation device G.

FIG. 14 is a diagram showing an example in which a reinforcing material made by the SLS method is used.

FIG. 15 is a view showing the structure of an easy fusion gold reproducing device U.

FIG. 16 is a view showing a structure of an easy-fusion-metal recycling apparatus U configured to also serve as an electric furnace H.

[Explanation of symbols]

 A Selective laser sintering (SLS) molding machine A1 Container A2 Recoater A3 Recoater drive A4 Laser head A5 Scanner A6 Elevator A7 Elevator drive A8 Feed screw A9 Controller C Modeler C1 Menu D CAD data D1 Surface shape data D2 External shape Data D3 Mold shape data F Easy fusion gold F1 Easy fusion gold melt G Liquid circulation device G1 High temperature glycerin tank G2 Room temperature glycerin tank G3 Pump G4 Valve G5 Discharge port H Electric furnace H1 Crucible H2 Glycerin bath H3 Heater H4 Thermostat H5 Outlet I Lever I2 Hammer J1 Base bracket J2 Fixing bracket J3 Clip bracket J4 Reinforcement M1 Mold M11 Cleaned mold M12 Unsolidified mold M2 Cast mold M21 Cast product M3 Finished product P Completed product Method P1 Mold manufacturing process P11 Data receiving process P12 Mold shape forming process P13 SLS molding process P2 Easy fusion casting process P21 Mold cleaning process P22 Mold smoothing process P23 Easy fusion melting process P24 Easy fusion casting process P25 Easy fusion cooling Process P3 Mold removal process P31 Die-cutting process P32 Die-cutting process P33 Casting product smoothing process Q Reference point R1 Surface shape R2 Outer shape R3 Mold shape S Material powder U Easy fusible metal recycling device U1 Screen U2 Heater U3 Water tank T1 Mold split surface T2 Bit pin T3 Support leg T4 Gate T5 Air handling T6 Clipping point T7 Fixed leg T8 Channel W Modeling object X1 Recoater drive signal X2 Scanner laser drive signal X3 Elevator drive signal Z Rapid prototyping peripheral device

Continued on the front page (72) Inventor Noriyuki Sadaoka 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Power & Electricity Development Division, Hitachi, Ltd. (72) Ryuichiro Iwano 7-2, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi, Ltd. Power and Electricity Development Division (72) Inventor Seiji Hayano 3105-1 Higashi-Naganuma, Inagi-shi, Tokyo F-term (reference) 4E093 TA10 4E094 AB71

Claims (22)

[Claims] 1. A mold manufacturing process for forming a mold from a thermoplastic material, and an easy fusion metal melted at a temperature lower than a softening point of the thermoplastic material is poured into the mold and solidified to form a cast product. A method of manufacturing a three-dimensional article, comprising: a gold casting step; and a mold removing step of dividing and removing the mold and removing the casting as a target three-dimensional article. 2. The method for manufacturing a three-dimensional product according to claim 1, wherein the thermoplastic material is a resin material or a composite material of a resin, and the mold manufacturing step includes partially firing the powder of the thermoplastic material. A method of manufacturing a three-dimensional product, comprising: a selective laser sintering (SLS) forming process of forming a thin layer by tying the thin layers to form the mold. 3. The method of manufacturing a three-dimensional product according to claim 1, wherein the mold manufacturing step includes a step of forming a flow path for heat exchange inside the mold, and the easy-fusion gold casting step. A mold cooling step of cooling the mold by circulating a cooling fluid through the flow path. 4. The method for manufacturing a three-dimensional product according to claim 1, wherein the easy-fusion-metal casting step includes a step of placing a reinforcing material in the mold before pouring the easy-fusion metal into the mold. A method for producing a three-dimensional article, comprising: 5. The method of manufacturing a three-dimensional product according to claim 4, wherein the mold manufacturing step includes a step of forming a flow path for heat exchange inside the mold, A method for manufacturing a three-dimensional article, comprising a mold heating step of heating the mold by circulating a heating fluid through the flow path. 6. The method for producing a three-dimensional article according to claim 4, wherein a metal piece having a melting point higher than that of the fusible alloy is used as the reinforcing material. 7. The method for manufacturing a three-dimensional product according to claim 4, wherein a metal powder having a melting point higher than that of the fusible alloy is partially sintered to form a thin layer, and the thin layers are stacked to form the reinforcing material. A method for producing a three-dimensional article, comprising a reinforcing material forming step of producing a three-dimensional article. 8. The method for manufacturing a three-dimensional article according to claim 7, further comprising a reinforcing material infiltration step of infiltrating a metal into the porous reinforcing material. 9. A mold shape design apparatus for supporting the creation of the mold shape in the method for manufacturing a three-dimensional article according to claim 1, wherein all or a part of the shape of the target three-dimensional article is outside. A mold shape designing apparatus, characterized in that the mold shape designing apparatus is provided with an offset mold creating means for offsetting the mold to create an outer shape of the mold. 10. The mold shape design apparatus for supporting the creation of the mold shape in the method for manufacturing a three-dimensional article according to claim 9, wherein the mold for creating a partial shape for mutually aligning the plurality of divided molds is provided. A mold shape design device comprising a matching shape creating means. 11. The mold shape design apparatus for supporting the creation of the mold shape in the method for manufacturing a three-dimensional article according to claim 9, wherein a partial shape for fixing the mold to a retainer that suppresses deformation of the mold is created. A mold shape designing apparatus, comprising: a retainer fixed shape creating means. 12. The mold shape designing apparatus for creating the mold shape in the method for manufacturing a three-dimensional article according to claim 3 or 5, further comprising a flow path forming means for adding the shape of the flow path to the shape of the mold. A mold shape design apparatus characterized by the above-mentioned. 13. The reinforcing member shape designing apparatus for creating the shape of the reinforcing member according to the method for manufacturing a three-dimensional article according to claim 7, wherein the reinforcing member creates the shape of the reinforcing member based on the shape of the target three-dimensional article. A reinforcing member shape designing apparatus comprising a shape creating means. 14. The easy fusion financial solution apparatus for melting the easy fusion metal in the method for producing a three-dimensional article according to claim 1, wherein the molten easy fusion metal is 5 ° C. or less from the softening point of the thermoplastic material. An easy fusion financial solution device, comprising a temperature controller for keeping the temperature at 20 ° C. lower. 15. A heating fluid circulating apparatus for supplying the heating fluid for heating the mold in the method for producing a three-dimensional article according to claim 5, wherein the heating fluid is higher than a softening point of the thermoplastic material. A heating fluid circulating device comprising: a temperature controller for maintaining a temperature lower than the melting point of the fusible alloy; and a pump for discharging the heating fluid to the flow path. 16. The heating fluid circulation device according to claim 15, wherein the heating fluid is a polyhydric alcohol or a mixture containing a polyhydric alcohol as a main component. 17. The heating / cooling fluid circulation device used in the mold cooling step according to claim 3 or the mold heating step according to claim 5, wherein the heating fluid is lower than a softening point of the thermoplastic material. A temperature controller for maintaining the temperature higher than the melting point of the fusible alloy; a pump for discharging the heating fluid or the cooling fluid to the flow channel; and the heating fluid or the cooling to one flow channel. A heating / cooling fluid circulation device, comprising: a valve for switching the discharge of the working fluid. 18. An easy-fusion alloy regenerating apparatus which takes out the easy-fusion alloy by melting the unnecessary three-dimensional article by the method for manufacturing a three-dimensional article according to any one of claims 6 to 8, wherein: An easy fusion metal reproducing apparatus, comprising: a screen for separating the reinforcing material from the easy fusion gold. 19. The easy-fusion financial solution apparatus according to claim 14, wherein the easy-fusion financial solution apparatus also serves as the heating fluid circulation device according to claim 15. 20. The easy fusion financial solution apparatus according to claim 14, wherein the easy fusion financial solution apparatus also serves as the easy fusion money reproduction apparatus according to claim 18. 21. The easy fusible alloy used in the method for producing a three-dimensional article according to claim 1, wherein bismuth and tin are contained as main components. 22. The easy fusion metal used in the method for producing a three-dimensional article according to claim 21, wherein the easy fusion metal contains 0.5% to 5% of copper or 0.5% to 5% of silver. Fusion money.