JP6960867B2 - Laminated modeling equipment - Google Patents

Description

In the present invention, for example, a three-dimensional shaped product is produced by repeating a step of selectively solidifying a powder bed of each layer while laminating a powder bed formed of a powder material made of metal particles in a vacuum chamber. It is related to a modeling device.

A three-dimensional shaped object is created by selectively solidifying the powder bed of each layer while laminating the powder bed formed of a powder material made of metal particles that can be melted and solidified by irradiation with an electron beam in a vacuum chamber. Laminated molding equipment to be manufactured is known. In the laminated modeling apparatus using the electron beam as described above, since the powder material is negatively charged by the irradiation of the electron beam, the individual powder materials may repel each other due to the Coulomb force and the powder material may scatter. Therefore, there is a method in which an auxiliary gas is introduced into the vacuum chamber of the apparatus and the auxiliary gas is positively charged in the vicinity of the irradiation point of the electron beam to electrically neutralize the powder material (see, for example, Patent Document 1). .. Further, there is a method of irradiating a material arranged on a work area with an electron beam while supplying a reactive gas that increases the conductivity of the powder surface of the powder material (see, for example, Patent Document 2).

Special Table 2010-526964A Japanese Patent Application Laid-Open No. 2011-506761

However, since the gas introduced into the vacuum chamber easily diffuses, in the ones described in Patent Document 1 and Patent Document 2, the gas for preventing the scattering of the powder material is introduced into the entire vacuum chamber. In particular, there is a problem that when the vacuum chamber becomes large, the amount of gas required increases and the production cost increases, as in the case of modeling a large-sized object.

The present invention has been made to solve the above-mentioned problems, and while preventing the powder materials charged by the irradiation of the electron beam from repelling each other and scattering, the vacuum chamber is used to prevent the scattering. It is intended to obtain a laminated molding apparatus capable of reducing the amount of gas introduced into the.

The laminated molding apparatus of the present invention manufactures a three-dimensional shaped object by repeating a step of selectively solidifying the powder bed of each layer while laminating a powder bed formed of a powder material in a vacuum chamber. An apparatus, which is an electron beam irradiating means for irradiating a powder bed with an electron beam for solidifying a powder material, a mounting table provided in the scanning range of the electron beam and having an adjustable height, and a mounting table mounted on the mounting table. a powder bed forming unit for forming a powder bed, the gas to be positive ionized by irradiation of the electron beam and a gas introducing portion for introducing the passing area of the electron beam, the gas introduction portion than Knudsen number is 0.3 The gas is introduced into the passage region in the state of a large molecular flow .

According to the laminated molding apparatus of the present invention, since the gas introduction portion for ejecting the molecular flow of the gas cationized by the irradiation of the electron beam into the passing region of the electron beam is provided, the powder materials charged by the irradiation of the electron beam are mutually charged. It is possible to reduce the amount of gas introduced into the vacuum chamber in order to prevent scattering while preventing repulsion and scattering.

It is the schematic which shows the laminated modeling apparatus in Embodiment 1 of this invention. It is a side view which shows the gas introduction part which concerns on Embodiment 1 of this invention. It is a top view which shows the gas introduction part which concerns on Embodiment 1 of this invention. It is the schematic which shows the laminated modeling apparatus in Embodiment 2 of this invention. It is a side view which shows the gas introduction part which concerns on Embodiment 2 of this invention. It is a top view which shows the gas introduction part which concerns on Embodiment 2 of this invention.

Embodiment 1.
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 2B. FIG. 1 is a schematic view showing a laminated modeling apparatus according to the first embodiment. In the laminated modeling apparatus 100, the electron gun 2, that is, the electron beam irradiating means is housed in the electron gun chamber 3, that is, the storage chamber, which is installed above the vacuum chamber 1. The electron gun 2 faces the floor portion 1a of the vacuum chamber 1 and irradiates the electron beam EB to a predetermined scanning range. The floor portion 3a of the electron gun chamber 3 is provided with an opening 3b for communicating the electron gun chamber 3 and the vacuum chamber 1, and the electron beam EB emitted from the electron gun 2 passes through the opening 3b in the vacuum chamber. It is irradiated in 1. The opening 3b can be opened and closed by a shutter (not shown), and the vacuum chamber 1 and the electron gun chamber 3 are shut off by closing the opening 3b except when the electron beam EB is irradiated, and the degree of vacuum in the vacuum chamber 1 is reduced. It is possible to maintain.

The electron beam EB can operate the irradiation point by deflecting it by an electromagnetic force. Further, the electron beam EB spreads from the electron gun 2 to the floor portion 1a at a predetermined spreading angle. In the first embodiment, the region where the path of the electron beam moves when the irradiation destination of the electron beam EB moves within the scanning range is defined as the passing region of the electron beam EB, and the passing region in the vacuum chamber 1 is the passing region S1 and the electrons. The passing area in the gun chamber 3 is defined as the passing area S2. The area of the opening 3b is equal to or larger than the horizontal cross-sectional area of the passing region S2 at the height of the floor 3a, and the electron beam EB passes through the opening 3b regardless of the path in the passing region S2. It is designed to enter the vacuum chamber 1. Further, since the spread of the electron beam EB is larger toward the lower side, the horizontal cross-sectional area of the passing region S1 is larger than the horizontal cross-sectional area of the passing region S2.

On the floor portion 1a, a molding region portion 1b on which the powder material 7 which is a raw material of the three-dimensional laminated model 8 is spread is formed in the scanning range of the electron beam EB. The bottom surface of the modeling area 1b is formed by a work base 5 whose height can be adjusted by the elevating mechanism 6, that is, a mounting table, and the depth of the modeling area 1b is adjusted by raising and lowering the work base 5. ..

On the floor portion 1a, a powder floor forming mechanism 92 for laying the powder material 7 stored in the powder box 91 on the work base 5 is installed. The powder bed forming mechanism 92 moves and reciprocates the upper part of the modeling region portion 1b to supply a predetermined amount of the powder material 7 into the modeling region portion 1b, and spreads the powder material 7 on the work base 5. The powder box 91 is, for example, a rectangular parallelepiped box, and when the powder bed forming mechanism 92 comes downward, the powder material 7 is dropped and the powder material 7 is supplied to the powder bed forming mechanism 92. The powder material 7 is a powdery material that solidifies to form a three-dimensional model, and is melt-solidified or sintered and solidified by being irradiated with an electron beam EB from the electron gun 2. The powder material 7 is, for example, a powder material of metal particles such as a cobalt-chromium molybdenum alloy or a titanium alloy, but is not limited to this, and may be melt-solidified or sintered by irradiation with an electron beam EB. ..

Further, a gas introduction portion 10 is installed on the floor portion 1a. The gas introduction unit 10 is arranged in the vicinity of the modeling region portion 1b, and locally introduces the scattering prevention gas G in the molecular flow state into the passage region S1 of the electron beam EB via the ejection pipe 104. Further, the gas introduction unit 10 is connected to the gas supply unit 13 provided on the side wall of the vacuum chamber 1 via a pipe 103. The gas supply unit 13 is connected to a container 12 provided outside the vacuum chamber 1 via a pipe 102, and supplies the anti-scattering gas G held in the container 12 to the gas introduction unit 10. The container 12 is connected to the vacuum pump 11 via a pipe 101, and holds the anti-scattering gas G decompressed by the vacuum pump 11.

The gas introduction section 10 and the plate 4 will be described in more detail. 2A and 2B are a side view and a plan view showing the gas introduction unit 10. Actually, the powder material 7 is spread around the plate 4, but in FIGS. 2A and 2B, the powder material spread around the plate 4 is omitted. The plate 4 is, for example, a metal plate having a square cross section, and a groove portion 4a is provided in a range where the electron beam EB is irradiated. When the powder material 7 is spread on the work base 5, the powder material 7 is also spread in the groove 4a to form the first layer powder floor 71.

The gas introduction unit 10 is provided with a plurality of ejection pipes 104 on the side surface of the electron beam EB on the passing region S1 side. Each ejection pipe 104 is, for example, a thin tube having a circular cross section, is provided in the gas introduction portion 10 at a height V1 from the floor portion 1a, and extends from the gas introduction portion 10 toward the passage region S1 of the electron beam EB. .. The end of the ejection pipe 104 on the passing region S1 side and the groove portion 4a are separated by a predetermined distance H1. The plurality of ejection pipes 104 are arranged along the width direction of the plate 4, and the number thereof is set according to the width of the plate 4, and the anti-scattering gas G ejected from the ejection pipe 104 covers the entire upper portion of the plate 4. It is designed to cover. Therefore, no matter what path the electron beam EB passes through in the passage region S1, the electron beam EB irradiates the shatterproof gas G, and the shatterproof gas G is cationized by the irradiation of the electron beam EB. NS. The shatterproof gas G is not particularly limited as long as it is cationized by irradiation with the electron beam EB, but from the viewpoint of preventing oxidation of the powder material, an inert gas such as argon or helium is used. Is desirable.

The anti-scattering gas G is introduced from the ejection pipe 104 as a molecular flow. More specifically, the Knudsen number K, which is an index indicating whether the flow of the shatterproof gas G is a viscous flow or a molecular flow, is set to be larger than 0.3. In the first embodiment, since the representative length of the system is the inner diameter D of the ejection pipe 104, the Knudsen number K is K = λ / D using the mean free path λ of the shatterproof gas G and the inner diameter D of the ejection pipe 104. It is represented by. The Knudsen number K is set by adjusting the mean free path λ and the inner diameter D of the ejection pipe 104. The mean free path λ can be adjusted by adjusting the pressure of the shatterproof gas G. When the inner diameter D is reduced to adjust the Knudsen number K, the number of ejection pipes 104 is increased according to the amount of change in the inner diameter D, and the width of the entire ejection pipe 104 is adjusted to the width of the plate 4.

Since the anti-scattering gas G introduced as a molecular flow is suppressed from diffusing as in the case of a viscous flow and flows linearly from the ejection pipe 104 as shown in FIG. 2B, the anti-scattering gas G is It is locally introduced into the passing region S1 of the electron beam EB.

Next, the operation will be described. After evacuating the inside of the vacuum chamber 1 to stabilize the degree of vacuum in the vacuum chamber 1, the work base is set so that the height from the upper surface of the plate 4 to the upper surface of the floor portion 1a is one layer of the powder floor 71. The height of the work base 5 is adjusted, and the work base 5 is heated by irradiating the work base 5 with an electron beam for preheating. The electron beam for preheating has a lower output than the electron beam EB that melts and solidifies the powder material by adjusting beam parameters such as beam output, beam focus, and beam scanning speed. After heating the work base 5, the powder material 7 is spread on the work base 5. At this time, the powder material 7 is also spread over the groove 4a of the plate 4 to form the first layer powder bed 71. The powder bed 71 of the first layer is preheated by heat conduction from the heated work base 5. As a result, the temperature of the powder material forming the first layer powder bed 71 rises, so that the powder material is negatively charged by the irradiation of the electron beam EB, and the powder materials are prevented from repelling and scattering due to the Coulomb force. NS. The reason why the scattering of the powder material can be suppressed by the above-mentioned temperature rise is that the electric charge is conducted due to the decrease in the electric resistance due to the temperature rise, and the charge of the powder material is suppressed.

After preheating the powder bed 71, the anti-scattering gas G held in the container 12 is sent to the gas introduction section 10, and the anti-scattering gas G is locally introduced into the passing region S1 of the electron beam EB through the ejection pipe 104.

Next, the electron beam EB is irradiated to the powder bed 71 of the first layer according to a preset irradiation pattern, and the powder material of the powder bed 71 of the first layer is selectively solidified. At this time, in the vicinity of the powder bed 71, the anti-scattering gas G introduced into the passing region S1 is irradiated to the electron beam EB, and cations are generated by the interaction between the anti-scattering gas G and the electron beam EB. The cations electrically neutralize the powder material 7 of the first layer powder bed 71, which is negatively charged by irradiation with the electron beam EB. When the solidification of the powder material is completed for the first layer powder bed 71, the irradiation of the electron beam EB is stopped, the height of the work base 5 is lowered by the thickness of the second layer powder bed (not shown), and the first layer A second layer of powder bed is formed on the first layer of powder bed 71 in the same manner as in the case of the eyes. Since the temperature of the second layer powder bed rises due to the residual heat of the first layer powder bed 71 solidified by the electron beam EB, the powder material forming the second layer powder bed becomes negative due to the irradiation of the electron beam EB. It is charged and repelled by the Coulomb force, and the scattering of the powder material 7 is suppressed.

After the formation of the second layer powder bed, the anti-scattering gas G is locally introduced into the passing region S1 of the electron beam EB as in the case of the first layer, and the electron beam EB is irradiated to irradiate the second layer powder bed. The powder material of 71 is selectively solidified. Before irradiating the second layer powder bed with the electron beam EB, the second layer powder bed may be repreheated by irradiating the electron beam for preheating. The same applies to the third and subsequent layers, and the process of selectively solidifying the powder beds of each layer while laminating the powder beds is repeated to manufacture the three-dimensional laminated model 8 on the work base 5.

The effect of the first embodiment will be described. In order to confirm the effect of the first embodiment, the electron beam EB when the negatively charged powder material repels and scatters due to the Coulomb force in the case where the anti-scattering gas G is locally introduced and the case where the anti-scattering gas G is not introduced. The current values were measured as "allowable current values" and compared. In the measurement of the permissible current value, first, the degree of vacuum in the vacuum chamber 1 is stabilized, the powder material 7 made of metal particles is uniformly spread in the groove 4a with a thickness of 100 μm, and then the powder material 7 spread is covered. And irradiate the electron beam EB. Further, the powder material is not preheated, and the powder material 7 at room temperature is irradiated with the electron beam EB. Under this condition, the current value of the electron beam EB is gradually increased, and the current value of the electron beam EB is measured when the scattering of the powder material is confirmed. The presence or absence of scattering of the powder material 7 is confirmed by visually checking the inside of the vacuum chamber 1 from the viewing window (not shown) of the vacuum chamber 1 for about 2 seconds after the irradiation of the electron beam EB. In the comparison of the permissible current values, the measurement is performed a plurality of times each when the shatterproof gas G is locally introduced and when it is not introduced, and the average value is calculated and compared. As a result of measuring the permissible current value as described above, the average value of the permissible current value when the shatterproof gas G is not introduced is about 0.6 mA, which is the permissible current value when the shatterproof gas G is locally introduced. The average value was about 1.1 mA, and it was confirmed that the introduction of the local anti-scattering gas G had the effect of increasing the permissible current value. Even if the introduction of the anti-scattering gas G is local, such an effect is obtained by the cations generated by the interaction between the anti-scattering gas G introduced into the passing region S1 and the electron beam EB. It is considered that the charged powder material 7 was electrically neutralized.

According to the first embodiment, it is possible to reduce the amount of the anti-scattering gas introduced into the vacuum chamber while preventing the powder materials charged by the irradiation of the electron beam from repelling each other and scattering. More specifically, since it is provided with a gas introduction unit that introduces a molecular flow of the anti-scattering gas that is cationized by irradiation of the electron beam into the passing region of the electron beam, the anti-scattering gas is locally introduced into the passing region of the electron beam. It is possible to do. Therefore, it is not necessary to introduce the anti-scattering gas into the entire vacuum chamber, and the amount of the anti-scattering gas introduced into the vacuum chamber is reduced. Reducing the amount of the shatterproof gas introduced can reduce the cost of the shatterproof gas, suppress the increase of gas molecules in the vacuum chamber, and suppress the decrease in the degree of vacuum. As a result, the decrease in the energy of the electron beam due to the collision between the gas molecule of the anti-scattering gas and the electron beam is also suppressed, so that the increase in the amount of energy input to the electron beam can be suppressed.

Further, since the gas introduction portion is installed on the floor portion of the vacuum chamber, the anti-scattering gas is introduced in the vicinity of the powder bed, and the scattering of the powder material can be prevented more effectively.

Embodiment 2.
Hereinafter, Embodiment 2 of the present invention will be described with reference to FIGS. 3 to 4B. The same or corresponding parts as those in FIGS. 1 to 2B are designated by the same reference numerals, and the description thereof will be omitted. The second embodiment is different from the second embodiment in that the gas introduction unit is installed in the electron gun chamber. FIG. 3 is a schematic view showing the laminated modeling apparatus according to the second embodiment. In the laminated modeling apparatus 200, a gas introduction portion 20 is installed on the floor portion 3a of the electron gun chamber 3. The gas introduction unit 20 is arranged in the vicinity of the opening 3b, and locally introduces the scattering prevention gas G in the molecular flow state into the passage region S2 of the electron beam EB via the ejection pipe 204. Further, the gas introduction unit 20 is connected to the gas supply unit 23 provided on the side wall of the electron gun chamber 3 via a pipe 203. The gas supply unit 23 is connected to the container 12 via a pipe 202, and supplies the anti-scattering gas G held in the container 12 to the gas introduction unit 20.

The gas introduction unit 20 will be described in more detail. 4A and 4B are a side view and a plan view showing the gas introduction unit 20. The gas introduction portion 20 is provided with a plurality of ejection pipes 204 on the side surface on the opening 3b side. The ejection pipe 204 is, for example, a plurality of thin pipes having a circular cross section, is provided in the gas introduction portion 20 at a height V2 from the floor portion 3a, and extends from the gas introduction portion 20 side toward the opening 3b. The end of the ejection pipe 204 on the opening 3b side and the opening 3b are separated by a predetermined distance H2. The plurality of ejection pipes 204 are arranged along the width direction of the opening 3b, the number of which is set according to the width of the opening 3b, and the anti-scattering gas G ejected from the ejection pipe 204 is the opening 3b. It is designed to cover the entire upper part. Therefore, no matter what path the electron beam EB passes through in the passage region S2, the electron beam EB irradiates the shatterproof gas G, and the shatterproof gas G is cationized by the irradiation of the electron beam EB. NS.
The point that the anti-scattering gas G is introduced as a molecular flow from the ejection pipe 204 and locally introduced into the passage region S2 is the same as that of the first embodiment. Further, when the inner diameter D of the ejection pipe 204 is reduced to adjust the Knudsen number K, the number of the ejection pipes 204 is increased according to the amount of change in the inner diameter D, and the width of the entire ejection pipe 204 is set to the width of the opening 3b. match.

Since other configurations are the same as those in the first embodiment, the description thereof will be omitted.

Next, the operation will be described. Similar to the first embodiment, the degree of vacuum in the vacuum chamber 1 is stabilized, the height of the work base 5 is adjusted, and then the work base 5 is heated by the electron beam for preheating. After heating the work base 5, the powder material 7 is spread on the work base 5 and in the groove 4a of the plate 4 to form the first layer powder bed 71 in the groove 4a. The powder bed 71 of the first layer is preheated by heat conduction from the work base 5. After preheating the powder bed 71, the anti-scattering gas G held in the container 12 is sent to the gas introduction section 20, and the anti-scattering gas G is locally introduced into the passing region S2 of the electron beam EB through the ejection pipe 204.

After the shatterproof gas G is introduced into the passage region S2, the electron beam EB is irradiated to the powder bed 71 of the first layer according to a preset irradiation pattern. At this time, the shatterproof gas G and the electron beam EB interact with each other in the vicinity of the opening 3b in the electron gun chamber 3 to generate cations. This cation enters the vacuum chamber 1 through the opening 3b, reaches the vicinity of the powder bed 71 of the first layer, and is negatively charged by the irradiation of the electron beam EB. Material 7 is electrically neutralized. When the solidification of the powder material of the first layer powder bed 71 is completed, the irradiation of the electron beam EB is stopped, and the height of the work base 5 is lowered by the thickness of the second layer powder bed (not shown). After that, the second layer powder bed is formed on the first layer powder bed 71 in the same manner as in the case of the first layer. The following is the same as that of the first embodiment, and thus the description thereof will be omitted.

According to the second embodiment, since the gas introduction section for introducing the molecular flow of the anti-scattering gas into the passing region of the electron beam is provided as in the first embodiment, the powder materials charged by the irradiation of the electron beam repel each other. It is possible to reduce the amount of the anti-scattering gas introduced into the vacuum chamber while preventing the scattering.

In addition, the amount of shatterproof gas to be introduced can be further reduced. More specifically, since the gas introduction section for introducing the anti-scattering gas into the passing region of the electron beam is installed in the electron gun chamber, the width to be covered by the ejection pipe provided in the gas introduction section is larger than that of the first embodiment. Is also getting smaller. This is because, as described above, the electron beam has a predetermined spreading angle, and the spreading becomes larger toward the lower side. Therefore, the horizontal cross-sectional area of the passing region in the electron gun chamber is smaller than the horizontal cross-sectional area of the passing region in the vacuum chamber. Because. Since the width to be covered by the ejection pipe is the width of the passage region of the electron beam, the width to be covered by the ejection pipe in the second embodiment is the width that the ejection pipe needs to cover in the first embodiment. It is possible to reduce the number of ejection pipes and to further reduce the amount of anti-scattering gas to be introduced.

Further, in the present invention, the embodiments and configurations can be appropriately combined, and the configurations can be partially modified or omitted without departing from the spirit of the present invention.

1 Vacuum chamber, 1a floor, 1b modeling area, 2 electron gun, 3 electron gun chamber, 4 plate, 4a groove, 5 work base, 7 powder material, 71 powder floor, 8 three-dimensional laminated model, 10, 20 Gas introduction part, 104, 204 ejection pipe, 100, 200 laminated molding equipment, EB electron beam, G shatterproof gas, S1, S2 passage area,

Claims (3)

It is a laminated molding device that manufactures a three-dimensional shaped object by repeating the process of selectively solidifying the powder bed of each layer while laminating the powder bed formed of the powder material in a vacuum chamber.
An electron beam irradiation means for irradiating the powder bed with an electron beam for solidifying the powder material,
A mounting table provided in the scanning range of the electron beam and whose height can be adjusted,
A powder bed forming portion that is placed on the above-mentioned stand and forms the powder bed, and a powder bed forming portion.
And a gas inlet for introducing a gas to a cation by irradiation of the electron beam passing region of the electron beam,
The gas introduction unit is a laminated molding apparatus characterized in that the gas is introduced into the passage region in a state of a molecular flow having a Knudsen number of more than 0.3. The laminated molding apparatus according to claim 1, wherein the gas introduction portion is installed on a floor portion having a modeling region portion on which the powder material is spread. The laminated modeling device according to claim 1, wherein the gas introduction unit is installed in a storage chamber for accommodating the electron beam irradiation means.

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