JPH11227053A - Three-dimensionally shaping method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent intermediate laminates during shaping from becoming unshapable due to the warpage by its thermal stress, in a three-dimensionally shaping device, which forms a shape by laminating polymer films. SOLUTION: In this three-dimensionally shaping method, a three dimensional solid shape is laminatingly shaped through a stock sheet feeding process, in which a stock sheet P having a rear surface applied with a hot melt adhesive thereon is fed onto the top surface of intermediate laminates W under lamination of a shaping table 11, a heating and pressing process, in which the stock sheet P is heated and then pressed against and bonded to the top surface of the intermediate laminates W, and a cutting press for cutting the stock sheet P into a predetermined shape. This stock sheet P is made of a polymer film, on which a large number of pores are formed. As the polymer film, a polyethylene terephthalate film having a thickness of 0.127 mm and pores, and the size of each of which is 1 nm-50 μm, is exempled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional forming method for forming a three-dimensional three-dimensional shape by repeating the operation of laminating thin material sheets and cutting the same into a predetermined shape.

[0002]

2. Description of the Related Art As a three-dimensional forming method of this kind, there is a technique disclosed in, for example, Japanese Patent Application Laid-Open No. 6-278214. This is done by feeding a paper sheet coated on the back side with an adhesive that melts by heating to produce an adhesive force onto the upper surface of the intermediate laminated body that has been laminated up to that time, and then heating this paper sheet with a hot roller while simultaneously heating the upper surface of the intermediate laminated body. Then, an operation of cutting the bonded paper sheet with a laser beam along the contour shape (slice data) of the formed object corresponding to the height position of the bonded paper sheet is repeated, thereby performing a three-dimensional three-dimensional shape additive manufacturing. Things.

[0003]

SUMMARY OF THE INVENTION The above prior art 3
In the three-dimensional molding method, paper sheets are laminated and bonded,
There is a problem in that the molded article after molding expands due to moisture absorption, resulting in dimensional irregularity and poor water resistance. In order to solve such a problem, it is conceivable to use a film made of a polymer such as polyethylene terephthalate instead of a paper sheet. However, the polymer film heated by the hot roller and adhered to the upper surface of the intermediate laminate shrinks as it cools due to heat radiation, causing shear stress between the film layers and causing the film to warp, causing the following problem.

That is, in this type of molding method, first, a base sheet is adhered to a molding table with a double-sided adhesive tape, and a material sheet is laminated and adhered thereon. The material sheet has a large linear expansion coefficient. When a polymer film is used, since the shear stress generated between the film layers due to shrinkage is large, the double-sided tape is peeled off at the peripheral portion of the intermediate laminate at the initial stage of the additive manufacturing and rises up from the modeling table. For this reason, there is a problem that the position of the polymer film to be cut is shifted from the focal point of the laser beam so that the cutting is not performed and modeling is impossible. This peeling is not limited to the adhesive portion of the double-sided tape, and may occur between film layers. This problem is particularly remarkable when the shaped object has a large planar shape, since the warpage due to the shear stress accompanying the shrinkage is extremely large at the four corners or the peripheral portion. An object of the present invention is to solve such a problem by using a polymer film having a large number of holes formed thereon as a polymer film used for lamination.

[0005]

According to the present invention, there is provided a three-dimensional forming method comprising: a step of forming an intermediate sheet on a forming table on which a material sheet having a back surface coated with an adhesive which is melted by heating to generate an adhesive force is applied; A three-dimensional three-dimensional shape is formed by a material sheet feeding step of feeding the upper surface of the laminate, a heating pressing step of heating the material sheet and pressing and bonding the upper surface of the intermediate laminate, and a cutting step of cutting the material sheet into a predetermined shape. In the three-dimensional modeling method for forming by lamination, the material sheet is made of a polymer film having a large number of holes formed therein. Since a large number of pores are formed in the polymer film used for lamination, the apparent modulus of longitudinal elasticity is greatly reduced, and the shear stress generated between the film layers due to shrinkage upon cooling is also reduced.

In the above invention, it is preferable that each pore has a size of 1 nanometer to 50 micrometers.
In this way, since the adhesive does not enter each hole and fill it, the decrease in the longitudinal elastic modulus due to the large number of holes is reliably maintained.

[0007] The material of the polymer film used in the invention of the preceding two aspects is preferably polyethylene terephthalate.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 3 and 4, the apparatus used in this embodiment includes a material sheet supply device 20 that feeds a material sheet P to an upper side of the intermediate laminated body W that has been stacked so far, A heating and pressing device 30 that heats and presses and adheres to the upper surface of the intermediate laminate W;
A cutting device 40 for cutting the bonded material sheet P into a predetermined shape, and a control device 5 for controlling the operation of each of these devices
5 is provided.

Material sheet P used in this embodiment
Are formed with a large number of fine pores continuous with each other, and a hot melt adhesive such as an ethylene-vinyl acetate copolymer is applied to the back surface thereof. The material sheet P of this embodiment has a thickness of 0.005 inches (=
0.127 mm) polyethylene terephthalate film (hereinafter simply referred to as PET film), and the pores are small enough to prevent the adhesive from entering (specifically, the pore diameter is 1 nm to 50 μm). It is manufactured by a known technique such as a blend stretching method, an extrusion stretching method, and an extraction method. Also, this adhesive is melted by heating and reacts to generate adhesive force,
It has no adhesive strength at room temperature. Material sheet P is PET
Not limited to the film, any polymer film having a certain degree of heat resistance, mechanical strength and dimensional stability can be used.

First, the material sheet supply device 20 will be described mainly with reference to FIG. The molding table 11 supporting the intermediate laminate W during lamination has four corners screw-engaged with four lifting feed screws 12 supported on a machine frame (not shown) so as to be rotatable about a vertical axis. Screw 12 is pulley 12a
In addition, it is raised and lowered by being rotated in conjunction with a lifting motor 13 via a belt 14. A PET film P extending upward from a film roll Pa provided on one lower side of the lifting / lowering feed screw 12 passes through the outside of a pair of guide rollers 21a and 21b provided on the upper left and right sides, and is controlled by a control device 55. It is pulled out by the feed roller 22 which is driven to rotate by 23 and is taken up by the collecting roll Pb. The film roll Pa and the collection roll Pb are also driven by the motors 24 and 25.

As shown in FIG. 4, the heating and pressing device 30 is provided above the modeling table 11 and the material sheet supply device 20. X direction (right and left direction in the figure)
A pair of front and rear first guide rails (not shown) are provided, and the moving table 31 of the heating / pressing device 30 has an elongated shape extending in a horizontal Y direction orthogonal to the X direction, and both ends thereof are defined by the first guide rails. It is guided and supported, and is reciprocally translated in the X direction by a feed screw 33 that is rotated and driven by a motor 34. The moving table 31 has a PE along its longitudinal direction.
A predetermined temperature (2
Cylindrical hot roller 3 heated to 80-300 ° C.)
2 is rotatably supported and elastically urged downward. The heated hot roller 32 receives the P which has been sent to the upper side of the intermediate stacked body W being stacked with the movement of the moving table 31.
It rolls on the ET film P, and presses and adheres to the upper surface of the intermediate laminate W while heating. A limit switch 3 which is operated in contact with the upper surface of the intermediate laminated body W and the PET film P which rises together with the modeling table 11 when the upper surfaces thereof reach a predetermined height.
6 are provided.

The cutting device 40 uses a laser beam. As shown in FIG. 4, a second elongated second member extending in the Y direction is provided.
Both ends of the guide rail 44 are guided and supported by the above-mentioned first guide rail, and are reciprocally moved in the X direction by a feed screw 45 driven to rotate by a motor 46. A moving head 41 provided with a laser torch 42 and a mirror box 48b is guided and supported on the second guide rail 44 so as to be able to reciprocate along the Y direction, and is reciprocated by a driving mechanism (not shown). As a result, the laser torch 42, together with the moving head 41, forms the molding table 1 that supports the intermediate laminate W.
1 is moved in the X direction and the Y direction, and its trajectory is CNC-controlled by the control device 55. As shown in FIG.
The laser beam L from the laser oscillator 47 is reflected by a mirror built in mirror boxes 48a and 48b (the mirror box 48a is attached to one end of the second guide rail 44), and is irradiated downward from the laser torch 42 to be stacked in the middle. PET film P adhered to the upper surface of body W
Disconnect. The cutting device 40 is not limited to a device using a laser as described above, and may be a device using another cutting device such as an ultrasonic cutter.

Next, the operation of this embodiment will be described.
Prior to molding, a base sheet Wd (see FIG. 5) is adhered to the upper surface of the molding table 11 lowered as shown in FIG. 4 with a double-sided tape, and the limit switch 3 shown in FIG.
The movable table 31 is moved forward to a position where only the sheet 6 touches the sheet Wd, and the modeling table 11 is raised to a position where the sheet Wd contacts the limit switch 36 and stopped. Next, by operating the cutting device 40, the sheet Wd is cut by the laser beam L along the outermost square outline M1 on the outermost side of the intermediate laminate W, and the modeling table 11 is lowered,
The part outside the outer contour line M1 is peeled off from the upper surface of the modeling table 11, and the moving head 41 is retracted to the reference position shown in FIG.

Next, the PET roll Pa set in the machine frame
The PET film P pulled out from the guide rollers 21a,
21b, the collection roll Pb at the end thereof is set on the machine frame, and the PET film P is driven by the motors 23 to 25.
Is lightly tensioned so that each part is in the state shown in FIG. 4 and FIG. 1 (a). The following operation is automatically performed by the control device 55. First, the movable table 31 moves forward and only the limit switch 36 stops at the position where the limit switch 36 is applied to the intermediate laminate W. Then, the molding table 11 is raised, and the intermediate laminate W (in the case of the first rise, the base sheet Wd ) Is PET film P
When the switch is slightly pushed up, the limit switch 36 contacts the upper surface of the PET film P, and the molding table 11 is stopped. Next, the hot roller 32 that has been heated to the predetermined temperature once retreats to the reference position, advances until it passes through the intermediate laminate W, and then retreats to the reference position again. As a result, the hot roller 32 heated to a predetermined temperature, as shown in FIG.
d) Rolls reciprocatingly while pressing the PET film P in contact with the upper surface, and the PET film P is pressed against the upper surface of the intermediate laminate W (or sheet Wd) while the hot melt adhesive on the rear surface is heated and melted. It is glued.

When the heating and bonding are completed in this way, the cutting device 40 starts operating, and the laser beam L is applied to the upper surface of the intermediate laminated body W (the base sheet Wd in the case of the first operation). Then, the newly bonded PET film P is cut. Moving head 4 supporting laser torch 42
1 moves along an outer contour line M1, an inner contour line M2, a shaping contour line M3, and a dividing line M4 formed between the contour lines M2 and M3 shown in FIG. 2 according to a command from the control device 55. In such a manner, the object is moved in the X direction and the Y direction with respect to the modeling table 11. Then, the PET film P newly bonded to the upper surface of the intermediate laminate W is cut by the laser beam L emitted downward from the laser torch 42 toward the PET film P. FIG. 1C shows this cutting state.

When the cutting is completed, the molding table 11 is lowered, and the PET film P is sent to the collecting roll Pb side by the feed roller 22 so that the cut portion comes off the intermediate laminate W, and the PET film P is stacked for one cycle. Is completed. By repeating the above operation, a three-dimensional solid shape is formed by lamination.

FIG. 5 shows PE bonded to the upper surface of the intermediate laminate W.
FIG. 4 is an enlarged cross-sectional view showing a state in which the T film P is cut by the laser beam L, and is cut in the order of an outer contour line M1, an inner contour line M2, a shaping contour line M3, and a dividing line M4. Control device 5
Reference numeral 5 denotes the contour shape (slice data) of the modeling object corresponding to the height position given by the difference between the stop position of the modeling table 11 in the case of the base sheet Wd and the stop position of the modeling table 11 on the PET film P bonded this time. ) Is calculated, and the laser torch 42 is moved in the X and Y directions so that the inner edge of the shaping contour line M3 having a width slightly larger than the diameter of the laser beam L matches this slice data. Outer contour M1, inner contour M2, and dividing line M
The locus of No. 4 is the same for all the layers of the intermediate laminate W. Each cutting line M1 to M4 of each layer forming the intermediate laminate W
Is continuous in the vertical direction.

In the initial stage of the additive manufacturing, the sheet Wd serving as the base and the PET film P laminated thereon are rapidly cooled because they are close to the modeling table 11,
On the other hand, since the PET film P just adhered thereon is heated by the hot roller 32 and has a high temperature, the temperature gradient of the intermediate laminate W in the thickness direction becomes large. Further, the polymer film such as the PET film P used in this embodiment has a larger linear expansion coefficient than paper or the like, and therefore, the shear stress (thermal stress) generated between the respective film layers due to shrinkage due to heat radiation increases. Therefore, as it is, the bending stress of the four corners of the outer frame portion Wa of the intermediate laminate and the peripheral portion of the modeling portion Wb in the initial stage of the modeling increases, so that the bending stress that tends to curl upward increases. Adhesive double-sided adhesive sheet or PE
The adhesion between the layers of the T film P may be peeled off, and the intermediate laminate W may rise from the modeling table. In particular, when the planar shape of the modeled object is large, the risk increases. When such a floating occurs, the position of the PET film P which has just been bonded and is not cut is shifted from the focal point of the laser beam, so that cutting is not performed, and there is a possibility that the additive manufacturing becomes impossible.

However, in this embodiment, since a large number of continuous pores are formed in the PET film P used for lamination, the apparent longitudinal modulus of elasticity is greatly reduced. Since (including the shear stress generated between the film layers) is proportional to the modulus of longitudinal elasticity, the shear stress generated between the film layers is also reduced. Therefore, even if the planar shape of the modeled object is large, the warpage due to the shear stress at the four corners or the peripheral portion of the intermediate laminate does not become excessive, and the intermediate laminate peels off from the modeling table or between the film layers and floats. Additive manufacturing is not disabled.

Also, in this embodiment, since the size of the holes is 1 nm to 50 μm, the hot melt adhesive does not enter each hole and fill it. The decrease in the longitudinal elastic modulus due to the voids is reliably maintained, and the excessive shear stress due to shrinkage due to cooling is reliably prevented.

In the above embodiment, the PE
Although the cutting by the laser beam L is performed after the T film P is bonded by heating, the present invention can also be applied to a device that is bonded by heating after performing the cutting by the laser beam L.

[0022]

As described above, according to the present invention, since the shear stress generated between the film layers due to shrinkage upon cooling is reduced, even when the planar shape of the modeled object is large, the intermediate laminate can be removed from the modeling table. Alternatively, there is no possibility that the laminate molding becomes impossible due to peeling and floating between the film layers.

According to the structure in which the size of each hole is 1 nm to 50 μm, the decrease in the longitudinal elastic modulus due to the large number of holes is reliably maintained. Excessiveness is reliably prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a molding cycle of an intermediate laminate according to an embodiment of a three-dimensional molding method according to the present invention.

FIG. 2 is a view showing a cutting line of the intermediate laminate shown in FIG. 1 by cutting means.

FIG. 3 is a perspective view showing a schematic structure of an apparatus used in the embodiment shown in FIG. 1;

FIG. 4 shows a first state in which the lifting table is lowered.
It is the whole front view of an embodiment.

FIG. 5 is a cross-sectional view of an intermediate laminate during lamination.

[Explanation of symbols]

11: modeling table, P: material sheet, W: intermediate laminate.

Claims (3)

[Claims] 1. A material sheet supply step of feeding a material sheet having a back surface coated with an adhesive which generates an adhesive force by being melted by heating, to an upper surface of an intermediate laminate on a modeling table which has been laminated so far; A heating and pressing step of heating the material sheet and pressing and bonding to the upper surface of the intermediate laminate, and a cutting step of cutting the material sheet into a predetermined shape.
In a three-dimensional modeling method for layering a three-dimensional shape,
The method according to claim 3, wherein the material sheet is formed of a polymer film having a large number of holes. 2. The size of each of the holes is 1 nanometer or more.
The three-dimensional printing method according to claim 1, wherein the thickness is 50 micrometers. 3. The method according to claim 1, wherein the material of the polymer film is polyethylene terephthalate.