JP6132523B2 - Metal powder for metal stereolithography, manufacturing method of three-dimensional structure, and manufacturing method of molded product - Google Patents

Description

  The present invention is based on metal powder used for metal stereolithography that forms a desired three-dimensional shape by laminating a sintered layer obtained by irradiating a metal powder with a light beam, and metal stereolithography using the metal powder. The present invention relates to a method for manufacturing an injection mold, an injection mold made of the metal powder, and a molded product manufactured using the injection mold.

  Conventionally, injection molds are mainly manufactured by a method of removing a steel block for molds with a machine tool. In recent years, injection molds have been manufactured by a metal stereolithography method that forms a desired three-dimensional shape by laminating sintered layers obtained by irradiating a metal powder with a light beam and sintering.

  For example, in a metal stereolithography method, a method is known in which a model produced using a metal stereolithography metal powder containing 60 to 80% by weight of an iron-based powder made of chromium molybdenum steel is used as an injection mold. (See Patent Document 1).

Japanese Patent No. 3687667

  However, since the powder described in Patent Document 1 has a hardness as low as about HV400, when used in a plastic injection mold containing a reinforcing material such as glass or carbon, the mold is worn and damaged. Moreover, since the thermal conductivity is as low as about 10 W / mK, the mold cooling capacity is low. Furthermore, since the corrosion resistance to water is low, there is a problem that rusting and clogging occur when water is poured into a water pipe formed inside the mold in order to cool the injection molded plastic.

  This invention is made | formed in view of such a point, and provides the metal powder for metal stereolithography which can obtain the molded article excellent in hardness, thermal conductivity, and corrosion resistance. The present invention also provides a method for producing an injection mold using the metal powder, an injection mold comprising the metal powder, and a molded product produced using the injection mold. is there.

The metal powder for metal stereolithography of the present invention that solves the above problems is a metal powder for metal stereolithography, which includes Fe, Cr, Ni, Cu, and Ti, and includes Co, Si, or Mn. However, when Fe + Cr + Ni + Cu + Ti + Co + Si + Mn is 100% by weight, Fe is 70.9 % to 76% by weight, Cr is 10% to 13% by weight, Ni is 4% to 9% by weight, and Cu is 3 %. 0.7 wt% to 7 wt%, Ti 1.7 wt% to 3 wt%, Co 0 wt% to 4 wt%, Si 0 wt% to 0.5 wt%, and Mn 0 It is characterized by being not less than 0.5% and not more than 0.5%, Cr + Ni is not less than 16% and not more than 19%, Cu + Ti + Co is not less than 8% and Si + Mn is not less than 0% and not more than 1%.

The metal powder for metal stereolithography of the present invention that solves the above problems is a metal powder for metal stereolithography, which includes Fe, Cr, Ni, Cu, and Ti, and includes Co, Si, or Mn. However, when Fe + Cr + Ni + Cu + Ti + Co + Si + Mn is 100% by weight, Fe is 70.9 % to 76% by weight, Cr is 10% to 13% by weight, Ni is 4% to 9% by weight, and Cu is 3 %. 0.7 wt% to 7 wt%, Ti 1.7 wt% to 3 wt%, Co 0 wt% to 4 wt%, Si 0 wt% to 0.5 wt%, and Mn 0 It is characterized by being not less than 0.5% and not more than 0.5%, Cr + Ni is not less than 16% and not more than 19%, Cu + Ti + Co is not less than 8% and Si + Mn is not less than 0% and not more than 1%.

The method for producing a molded article according to the present invention is characterized by being molded using an injection molding die produced by using the above-described method for producing a three-dimensional structure .

  ADVANTAGE OF THE INVENTION According to this invention, the metal powder for metal stereolithography which can obtain the molded article excellent in hardness, thermal conductivity, and corrosion resistance can be provided. In addition, according to the present invention, there is provided a method for producing an injection mold using the metal powder, an injection mold comprising the metal powder, and a molded product produced using the injection mold. be able to.

It is a schematic sectional drawing which shows an example of the metal stereolithography apparatus used for the manufacturing method of the metal mold | die for injection molding of this invention. It is a schematic top view of the metal stereolithography apparatus shown in FIG. It is explanatory drawing which shows the preparation method of modeling process data. It is explanatory drawing which shows an example of a laser irradiation pattern. It is a scanning electron microscope (SEM) photograph which shows one example of the metal powder of this invention. It is a cross-sectional microscope picture of the magnification of 50 times of the metal stereolithography thing manufactured with the metal powder of this invention. It is explanatory drawing which shows an example of the metal mold | die for injection molding manufactured with the metal powder of this invention. It is explanatory drawing which shows an example of the metal mold | die for injection molding manufactured with the steel material block for metal mold | die.

  Embodiments of the present invention will be described in detail below.

  The metal stereolithographic metal powder of the present invention (also abbreviated as “metal powder”) is a metal that forms a three-dimensional shape by laminating a sintered layer obtained by irradiating a metal powder material with a light beam. Metal powder used for stereolithography, Fe 71% to 76% by weight, Cr 10% to 13% by weight, Ni 4% to 9% by weight, Cu 4% to 7% Wt% or less, Ti 2 wt% to 3 wt%, Co 0 wt% to 4 wt%, Si 0 wt% to 0.5 wt%, Mn 0 wt% to 0.5 wt% It is characterized by comprising the following: Cr + Ni: 16% by weight to 19% by weight; Cu + Ti + Co: 8% by weight to 9% by weight; and Si + Mn: 0% by weight to 1% by weight.

  In the metal powder of the present invention having the above composition, if Cr is less than 10% by weight, Ni is less than 4% by weight, and Cr + Ni is less than 16% by weight, the corrosion resistance is lowered.

  If Cr exceeds 13% by weight, Ni exceeds 9% by weight, and Cr + Ni exceeds 19% by weight, it is not preferable because the thermal conductivity decreases.

  If Cu is less than 4% by weight, Ti is less than 2% by weight, and Cu + Ti + Co is less than 8% by weight, the material hardness is not preferable.

  If Cu exceeds 7% by weight, Ti exceeds 3% by weight, Co exceeds 4% by weight, Cu + Ti + Co exceeds 9% by weight, and Si + Mn exceeds 1% by weight, the thermal conductivity is unfavorable.

  Note that Fe may contain inevitable impurities such as C which may be mixed in the powder manufacturing process.

  As a more preferable composition of the metal powder of the present invention, Fe is 70.9 wt% or more and 74.5 wt% or less, Cr is 11.7 wt% or more and 12.3% wt% or less, and Ni is 5.7 wt% or more. 6.3% by weight or less, Cu 3.7% to 4.3% by weight, Ti 1.7% to 2.3% by weight, Co 2.7% to 3.3% by weight In the following, it is desirable to contain Si in an amount of 0 to 0.3% by weight and Mn in an amount of 0 to 0.3% by weight.

  Next, the manufacturing method of the injection mold according to the present invention will be described.

  The method for producing an injection mold of the present invention includes a step of irradiating the metal powder with a light beam to obtain a first sintered layer, and forming the metal powder on the first sintered layer. It has the process of obtaining the metal mold | die which consists of a three-dimensional shaped molded object by repeating the process of irradiating a light beam, and laminating | stacking a 2nd sintered layer.

  FIG. 1 is a schematic cross-sectional view showing an example of a metal stereolithography apparatus used in the method for manufacturing an injection mold according to the present invention.

  FIG. 1A shows a powder laminating process, FIG. 1B shows an initial modeling process, and FIG. 1C shows a state just before the modeling is completed. In the figure, 1 is a base plate for creating a shaped object, 2 is a shaped object, 3 is a space (chamber) for creating a shaped object, 4 is a metal powder stored in the chamber 3, and 5 is in the chamber 3 Elevating table 6, 6 is a metal powder supplied to the chamber 3, 7 is a space (chamber) in which the metal powder 6 is stored, 8 is an elevating table provided in the chamber 7, and 9 is a metal powder 6 supplied to the chamber 3. A squeezing blade 10 is a laser beam for melting a metal powder spread on a base plate 1 placed in a chamber 3 by a predetermined thickness, 11 is a laser oscillator for oscillating the laser beam 10, and 12 is A scanning optical system for optically scanning the laser light 10 in the X and Y directions, 13 is a condensing lens for condensing the laser light 10 on the base plate 1, and 14 is a scanning optical system 12. Includes a light lens 13, itself shows a movable processing head in the X and Y directions.

  In the manufacturing process of the present invention, after the lifting table 5 is lowered by a predetermined thickness Δt and the lifting table 8 is raised by a predetermined thickness Δt ′ (Δt <Δt ′), the metal powder is transferred from the chamber 7 to the chamber 3 by the squeezing blade 9. (FIG. 1A). Thereafter, by irradiating only a necessary portion with the laser beam 10, the metal powder laid on the base plate 1 can be selectively melted and solidified (FIG. 1B). By repeating this operation, a desired three-dimensional shape (model 2) can be created (FIG. 1C).

  FIG. 2 is a schematic top view of the metal stereolithography apparatus shown in FIG. The chamber 3 and the chamber 7 are spaces closed in the X and Y directions, and have specifications that can store the metal powder 4 and the metal powder 6.

  In addition, the above only shows an example of a metal stereolithography apparatus used in the present invention, provided with a means for spreading metal powder for a predetermined thickness and a means such as a light beam for melting and solidifying the metal powder, It can be applied to the present invention.

  The method for manufacturing an injection mold according to the present invention further comprises forming a portion of the sintered layer that is not irradiated with a light beam in the method of laminating a sintered layer, and the portion of the metal that is not sintered that is not irradiated with the light beam. It has the process of removing the powder and forming a passage for passing the medium inside the injection mold. If the metal stereolithography apparatus shown in FIG. 1 and FIG. 2 is used, the water pipe formed inside the mold for cooling the injection-molded plastic can be brought as close as possible to the molded product. A mold can be made. Further, since the injection mold can make the temperature distribution of the injection molded product uniform, it is possible to obtain a molded product with very little deformation.

  FIG. 3 is an explanatory diagram showing a method of creating modeling data. Reference numeral 15 denotes a 3D-CAD model, and 16 denotes a cross-sectional shape model obtained by slicing an STL file generated from the 3D-CAD model 15 into N layers by a predetermined thickness Δt.

  FIG. 4 is an explanatory diagram showing an example of a laser irradiation pattern. Reference numeral 17 denotes an optical scanning path of the laser beam 10.

  The irradiation path of the laser beam 10 is created based on the 3D-CAD model 15. The STL file generated from the 3D-CAD model 15 is sliced by N layers by a predetermined thickness Δt, and each cross-sectional shape model 16 is set as an irradiation range. Any scanning path 17 such as a parallel line shape or a lattice shape can be considered as the optical scanning pattern of the laser beam 10 within the irradiation range, any of which may be used. The optical scanning means may be selected to use an optical system such as a galvanometer mirror provided in the processing head 14, move the processing head 14 itself, or perform these simultaneously.

  FIG. 5 is a scanning electron microscope (SEM) photograph showing an example of the metal powder of the present invention. In manufacturing a metal mold using the metal stereolithography apparatus as described above, what kind of metal powder is used is greatly related to the characteristics of the metal mold.

  FIG. 6 is a cross-sectional photomicrograph at a magnification of 50 times of a metal stereolithography manufactured with the metal powder of the present invention. It is the enlarged photograph which observed the surface which grind | polished the 20 mm square metal block manufactured by laser sintering with the metal stereolithography apparatus as shown in FIG. 1 using the metal powder of this invention at 50 times the magnification.

  The average particle size of the metal powder of the present invention is 10 μm or more and 50 μm or less, preferably 10 μm or more and 38 μm or less. The average particle diameter indicates an average particle diameter based on the volume of the powder particles, that is, a particle having an average volume of 10 μm or more and 50 μm or less in an aggregate of one powder whose particle size distribution is required. The particle size distribution and the particle size are calculated using a laser diffraction / scattering method in which a powder particle group is irradiated with laser light and an intensity distribution pattern of diffracted / scattered light emitted therefrom is evaluated. If the average particle diameter is less than 10 μm, a problem of powder lamination due to aggregation occurs, and if it exceeds 50 μm, a problem of reduction in modeling density occurs.

  The method for producing an injection mold according to the present invention is characterized by further comprising a step of performing at least one of a solution heat treatment and an age hardening heat treatment after the step of obtaining a mold made of a three-dimensional shaped article. . High hardness and high thermal conductivity can be obtained by applying a solution heat treatment and an age hardening heat treatment to the product after the shaping process. The solution heat treatment is a treatment in which a material is rapidly cooled so that no precipitate is formed during cooling after being heated and held at a temperature at which the alloy components of the material can be dissolved. The age hardening heat treatment refers to a treatment for precipitating alloy elements dissolved in the steel as fine intermetallic compounds by heating and holding the solution-treated heat-treated steel at a certain temperature.

  Examples of the invention are described in more detail below.

Example 1
Processing experiments were performed using the metal stereolithography apparatus shown in FIG. In the drawing, a fiber laser was used as the laser beam 10. The wavelength is 1070 nm, CW oscillation, the laser output is 400 W, and the beam spot diameter when condensing on the base plate 1 is 0.15 mm. As the scanning optical system 12, galvanometer mirrors were used in both the X direction and the Y direction. The optical scanning range by the galvanometer mirror is X250 mm and Y250 mm.

  The laminated thickness of the metal powder laid on the base plate 1 was 0.04 mm. After laying 0.04 mm of metal powder on the base plate 1 with the squeezing blade 9, the laser beam 10 was irradiated. The irradiation path is as shown in FIG. 4A, and the optical scanning speed (= laser scanning speed) by the galvanometer mirror is 900 mm / sec.

  The used metal powder is a metal stereolithography powder made of Cr, Ni, Cu, Ti, Co, Si, Mn, and Fe. The average particle diameter of the metal powder is 20 μm (0.02 mm). As the metal powder, powder 1 to powder 13 were used. The content (% by weight) of each component is as shown in Table 1 below.

  A test model of 60 mm × 60 mm × 20 mm was manufactured using a base plate of 150 mm × 150 mm × 25 mm using the metal powder and S50C material. After completion of the modeling process, the model was subjected to 500 ° C. age-hardening heat treatment, and each physical property value of hardness, thermal conductivity, and corrosion resistance was evaluated. In order to use it for a plastic injection mold containing a reinforcing material such as glass or carbon, the material hardness is required to be 50 HRC or more in consideration of mold durability. Further, in order to efficiently cool the injection-molded mold, it is required that the thermal conductivity is 15 W / mK or more and that the water pipe wall does not rust even when water is passed through the water pipe formed inside the mold. .

  Therefore, as an evaluation standard, the material hardness was measured with a Rockwell hardness tester or a Vickers hardness tester, and the hardness was evaluated as “◯” when the hardness was 50 HRC or more and “X” when it was less. The thermal conductivity was measured by a laser flash method. Corrosion resistance is determined by flowing general industrial water continuously for one month in the passage formed inside the molding assuming a passage for passing the medium formed inside the mold. What was confirmed was set as x. The experimental results are shown in Table 2 below.

  From the result of Table 2, the hardness, thermal conductivity, and corrosion resistance of the shaped article made of the metal powder of the present invention all exceeded the set values. On the other hand, when Cr and Ni are less than the component range of the present invention, the corrosion resistance is inferior. When Cu, Ti and Co are less than the component range of the present invention, the hardness is low, and the amount of alloy components other than Fe is low. When more than the component range of the present invention, the thermal conductivity was low. As mentioned above, the effect of this invention which can obtain the molded article excellent in hardness, thermal conductivity, and corrosion resistance is acquired by using the metal powder of the component range of this invention.

(Example 2)
Using the apparatus, processing method, and processing conditions as shown in Example 1, processing experiments were performed. The metal powder used is a metal shaping powder composed of the same components as powder 1, powder 2 and powder 3 shown in Example 1. In this example, four types of each were used with different average particle sizes.

  After the modeling process was completed, the density of the model was evaluated. If the modeling density is less than 95% by weight, voids called voids may be transferred to the injection-molded product to cause an appearance defect. Therefore, the modeling density is 95% by weight or more and ◯ is less. The experimental results are shown in Table 3 below.

  From the results in Table 2, the modeling density of the modeled article made of the metal powder having an average particle size of 10 μm or more and 50 μm or less exceeded the set value. On the other hand, the modeling object which consists of a powder with a small average particle diameter or a large powder resulted in a low modeling density.

(Example 3)
An injection mold as shown in FIGS. 7 and 8 was manufactured using the apparatus, the processing method, and the processing conditions as shown in Example 1.

  FIG. 7 is an explanatory view showing an example of an injection mold manufactured with the metal powder of the present invention. In FIG. 7, 18 is an injection-molded product, 19 is an injection mold produced by the metal stereolithography method, and 20 is a cooling water pipe formed inside the injection mold produced by the metal stereolithography method.

  FIG. 8 is an explanatory view showing an example of an injection mold manufactured with a steel block for molds. In FIG. 8, 18 is an injection-molded product, 21 is an injection-molding mold manufactured with a steel block for molds, and 22 is a cooling water pipe formed inside an injection-molding mold manufactured with a steel block for molds.

  An injection molding experiment was conducted using the injection mold shown in FIGS. The experimental results are shown in Table 4 below.

  According to the results shown in Table 4, the injection mold shown in FIG. 7 manufactured by the metal stereolithography method of the present invention can arrange the water pipe for cooling the injection molded plastic along the shape of the molded product. Therefore, the cooling time of the molded product can be shortened by 50% by weight as compared with the injection mold manufactured with the steel block for mold shown in FIG.

  The metal powder for metal stereolithography of the present invention can be used for injection molds, automobile parts, and the like because it can obtain a molded article having excellent hardness, thermal conductivity, and corrosion resistance.

DESCRIPTION OF SYMBOLS 1 Base plate 2 Modeling object 3 Modeling chamber 4 Metal powder in modeling chamber 5 Modeling side raising / lowering table 6 Metal powder in powder supply chamber 7 Powder supply chamber 8 Powder side raising / lowering table 9 Squeezing blade 10 Laser beam 11 Laser oscillator 12 Scanning optics System 13 Condensing lens 14 Laser processing head 15 3D-CAD model 16 Cross-sectional shape model 17 Scanning path of laser light 18 Injection molded product 19 Injection mold manufactured by metal stereolithography method 20 Injection manufactured by metal stereolithography method Cooling water pipe formed inside the molding die 21 Injection molding die made from the steel block for mold 22 Cooling water pipe formed inside the injection mold made from the steel block for mold

Claims (6)

Metal powder for metal stereolithography,
Including Fe, Cr, Ni, Cu, and Ti, and may include Co, Si, or Mn;
When Fe + Cr + Ni + Cu + Ti + Co + Si + Mn is 100% by weight,
Fe: 70.9 % to 76% by weight, Cr: 10% to 13% by weight, Ni: 4% to 9% by weight, Cu: 3.7 % to 7% by weight, Ti 1.7 wt% or more and 3 wt% or less, Co is 0 wt% or more and 4 wt% or less, Si is 0 wt% or more and 0.5 wt% or less, Mn is 0 wt% or more and 0.5 wt% or less, A metal powder for metal stereolithography, wherein Cr + Ni is 16 wt% or more and 19 wt% or less, Cu + Ti + Co is 8 wt% or more, and Si + Mn is 0 wt% or more and 1 wt% or less. 2. The metal powder for metal stereolithography according to claim 1, wherein an average particle size of the metal powder is 10 μm or more and 50 μm or less. A step of irradiating the metal powder for metal stereolithography according to claim 1 or 2 with a light beam to obtain a first sintered layer, and forming the metal powder on the first sintered layer to form a light A method for producing a three-dimensional structure by metal stereolithography, comprising the step of obtaining a three-dimensional shaped object by repeating a step of irradiating a beam and laminating a second sintered layer.   The three-dimensional structure is an injection mold, and in the method of laminating the sintered layer, a portion not irradiated with a light beam is formed on the sintered layer, and a portion not irradiated with the light beam is not sintered 4. The method for producing a three-dimensional structure according to claim 3, further comprising a step of removing the metal powder and forming a passage for allowing the medium to pass inside the injection mold.   The method for producing a three-dimensional structure according to claim 3 or 4, further comprising a step of performing at least one of a solution heat treatment and an age hardening heat treatment after the step of obtaining the three-dimensional structure.   A method for producing a molded product, characterized by being molded using an injection mold produced using the method for producing a three-dimensional structure according to claim 4 or 5.