JP4943937B2 - Manufacturing method of three-dimensional shaped object - Google Patents

Description

  The present invention relates to a method for manufacturing a three-dimensional shaped object that irradiates a metal powder with a light beam.

  Conventionally, a light beam is irradiated onto a powder layer formed of metal powder, the powder layer is melted to form a sintered hardened layer, a new powder layer is formed on the sintered hardened layer, and the light beam is irradiated. A method of manufacturing a three-dimensional shaped object by repeating irradiation and forming a sintered hardened layer is known (for example, see Patent Document 1).

  Thus, the manufacturing method for obtaining a three-dimensional shaped object from metal powder by irradiation with a light beam and its lamination can quickly obtain a complicated three-dimensional shaped object.

However, when the three-dimensional modeled object obtained by this manufacturing method is used as, for example, a plastic mold, various machining processes such as processing a through hole for an ejector pin are added after the modeling is completed. In this manufacturing method, a powder layer made of a metal powder is laid on a modeling plate as a base, a sintered hardened layer is formed by irradiating the powder layer with a light beam, and the sintered hardened layer is laminated. In order to improve the adhesion between the modeling plate and the three-dimensional modeled object, the first layer is modeled under a high-energy light beam condition. When receiving a high energy light beam, the surface of the modeling plate made of a steel material is hardened as a structure quenched by rapid heating and quenching in the vicinity of the portion irradiated with the light beam, resulting in a hardness difference in the modeling plate. Therefore, if drilling or turning with a lathe is performed on a hardened part after modeling is complete, drill tip breakage, drill shank breakage, bite tip breakage, etc. are likely to occur. Have difficulty.
JP-T-1-502890

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a method for manufacturing a three-dimensional shaped object that can be easily machined after the three-dimensional shaped object is formed. And

In order to achieve the above object, the invention of claim 1 includes a powder forming step of forming a powder layer by supplying a metal powder to a modeling plate on which a three-dimensional shaped object is formed, and a light beam is applied to the powder layer. An irradiation step of irradiating and melting the powder layer to form a sintered hardened layer, and repeating the irradiation step with the powder layer forming step to laminate the sintered hardened layer to form a three-dimensional shape product. In the manufacturing method of a three-dimensional shaped object to be shaped, during the irradiation step, irradiation is performed on a powder layer formed in the vicinity of a region where predetermined machining is planned after three-dimensional shape shaping in the shaping plate. The low-density sintered hardened layer is formed by making the energy of the light beam to be smaller than that of the light beam applied to the powder layer in the region where machining is not planned.

According to a second aspect of the present invention, in the method for manufacturing a three-dimensional shaped article according to the first aspect , at least a region where predetermined machining is planned after the three-dimensional shape shaping of the shaping plate is performed in advance. It is characterized by being made of a material that is hardened by heat treatment and hardly changes in hardness due to light beam irradiation .

The invention of claim 3 is the method for manufacturing a three-dimensional shaped article according to claim 1, wherein the three-dimensional shaped article is an injection mold, and the predetermined machining is for an ejector pin of the mold. In the case of hole processing, the injection process includes a step of forming a path for blowing gas into the processed hole when the ejector pin slides at the time of mold release in injection molding into a three-dimensional shaped object. Is formed by forming a low-density sintered hardened layer by reducing the irradiation energy of the light beam in the injection step.

According to the invention of claim 1 , the light beam is irradiated with low energy in the vicinity of the area where the machining of the modeling plate is scheduled after the three-dimensional shape modeling, and the hardness change due to quenching is small, The quenching depth is also shallow. Therefore, since the hardness difference between the portion irradiated with the light beam and the portion not irradiated is small in the machined region of the modeling plate, machining after modeling can be easily performed.

According to the second aspect of the present invention, the modeling plate is cured by performing heat treatment in advance, so that the hardness changes only slightly even when irradiated with the light beam. Therefore, since the difference in hardness between the portion irradiated with the light beam and the portion not irradiated within the region where the modeling plate is machined is small, machining after modeling can be easily performed.

According to the invention of claim 3 , when using the injection molding die of the three-dimensional shaped object, when the ejector pin slides at the time of releasing the molded product, the low-density from the outside of the three-dimensional shaped object. By blowing gas through the path formed by the sintered hardened layer, the slidability of the ejector pin is improved, the mold release becomes smooth, the molding cycle time is shortened, and the molding quality is improved. it can.

(First embodiment)
A method for manufacturing a three-dimensional shaped object according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a metal stereolithography machine used in the manufacturing method. The metal stereolithography machine 1 includes a modeling plate 3 on which a powder layer 21 of a metal powder 2 is laid, a modeling table 31 that holds the modeling plate 3 and moves up and down, and a reference for the thickness of the powder layer 21. The reference table 32, the supply tank 4 for supplying the metal powder 2, the material table 41 for raising the metal powder 2 in the supply tank 4, the squeegee 5 for forming the powder layer 21, and the beam for emitting the light beam L A transmitter 6, a condensing lens 61 that condenses the light beam L, and a galvanometer mirror 62 that scans the light beam L onto the powder layer 21 are provided.

  The composition of the metal powder 2 is, for example, chromium molybdenum steel (JIS-SCM440) powder, nickel (Ni) powder, copper manganese alloy (CuMn) powder, and graphite (C) powder, and the blending ratio is, for example, 70 wt. 0.3% by weight of graphite (C) powder is added to the powder of% SCM440, 20% by weight Ni, and 10% by weight CuMn. The material of the modeling plate 3 is, for example, S50C steel, and the hardness is HRC20. The squeegee 5 moves in the direction A and supplies the metal powder 2 on the material table 41 onto the modeling plate 3. The beam transmitter 6 is, for example, a carbon dioxide laser or fiber laser transmitter.

  FIG. 2 shows a flow of the manufacturing method, and FIG. 3 shows an operation of the manufacturing method. First, the modeling plate 3 is placed on the modeling table 31 (step S1). Next, the modeling table 31 is lowered so that the step between the upper surface of the modeling plate 3 and the upper surface of the reference table 32 has a length Δt (step S2). Next, the metal powder 2 on the material table 41 is supplied onto the modeling plate 3 by the squeegee 5. The squeegee 5 moves in the horizontal direction at the same height as the upper surface of the reference table 32, and forms a powder layer 21 having a thickness Δt on the modeling plate 3 (step S3) (see FIG. 3A). Steps S2 and S3 constitute a powder layer forming process.

  Next, the light beam L condensed by the condenser lens 61 is scanned to an arbitrary position by the galvanometer mirror 62 (step S4), and the powder layer 21 is melted and integrated with the modeling plate 3 to be sintered and hardened with a thickness Δt. The layer 8a is formed (step S5) (see FIG. 3B). Steps S4 and S5 constitute an irradiation process.

  Next, it is determined whether or not the shaping has been completed (step S6). If it has not been completed, the process returns to step S2, and steps S3, S4, and S5 are repeatedly executed to sinter harden on the sintered hardened layer 8a. The layer 8b is stacked (see FIGS. 3C and 3D).

  Thus, steps S2 to S6 are repeated until the modeling is completed, and the sintered layers 8a to 8f are stacked (see FIG. 3E). FIG. 4 shows an example of the three-dimensional shaped object 8 that is formed on the modeling plate 3 in this way.

  Next, path data for scanning the light beam L will be described. FIG. 5A shows the appearance of the product model to be manufactured by three-dimensional shape modeling, and FIG. 5B shows the shape of the slice plane in the horizontal direction of the product model. In manufacturing a three-dimensional shaped object, based on the three-dimensional CAD data when the product model 81 is designed, the slice surface of each layer 81a to 81f when the product model 81 is horizontally sliced at a predetermined interval Δt. Cross-sectional data is created, and the scanning path of the light beam L that irradiates the powder layer 21 is determined based on the cross-sectional data. By scanning the powder layer 21 with the light beam L according to the determined scanning path, the three-dimensional shaped object 8 can be formed.

  According to the above-described method, modeling of a three-dimensional shaped object is performed, but in the conventional manufacturing method, even when machining is performed on the modeling plate after modeling, light beam irradiation is performed on the area to be machined, Therefore, the modeling plate is hardened and it is difficult to perform machining after the modeling. An example of an operation for machining a three-dimensional shaped object after modeling will be described. Fig.6 (a) shows the cross section of the three-dimensional shape molded article shape | molded on the plate for modeling by the conventional manufacturing method. In this example, the three-dimensional shaped article 8 has an ejector pin hole 82 formed in the center, and a hole connected to the hole 82 is formed in the modeling plate 3. The region where the modeling plate 3 is joined to the three-dimensional modeled object 8 is irradiated with a high-energy light beam in order to improve the adhesion to the three-dimensional modeled object 8 in the irradiation process, and is rapidly quenched. Thus, a hardened structure E1 is formed and hardened.

  FIG. 6B shows a cross section of the three-dimensional modeled article 8 when the modeling plate 3 is drilled. When drilling is performed on the modeling plate 3 with the drill F to connect to the holes 82 of the three-dimensional modeled article 8, when the tip of the drill F reaches the curing region E1 of the modeling plate 3, the curing region E1 and the other Since there is a hardness difference between the regions, the cutting edge of the drill F may be lost or the drill shank may be broken.

  Therefore, in the present embodiment, in order to facilitate the drilling after modeling, the powder layer formed in the vicinity of the region where the drilling of the modeling plate 3 is scheduled is Do not perform light beam irradiation. FIG.6 (c) shows the cross section of the three-dimensional shaped molded object which did not perform light beam irradiation to the powder layer of the vicinity of the area | region where a punching process is planned. In this figure, a portion where a drilling process is scheduled is indicated by a one-dot chain line G. The three-dimensional shaped object 8 is not formed in the vicinity of the area where the drilling process is planned, and the area near the area where the modeling plate 3 is scheduled to be drilled is a hardened hardening area E1. is not. FIG. 6D shows a cross section of the three-dimensional model 8 at the time of drilling after modeling. The region to be drilled is not irradiated with a light beam, and no difference in hardness occurs. Therefore, even if the shaping plate 3 is drilled, there is little possibility that the cutting edge of the drill F is lost or the drill shank is broken, and the drilling can be easily performed. In addition, the region where the light beam irradiation is not performed is not only a powder layer in the vicinity of the region where drilling is performed after the three-dimensional shape modeling, but also as a powder layer in the vicinity of a region where machining such as turning or cutting is performed. Also good.

(Second Embodiment)
The manufacturing method of the three-dimensional shape molded article which concerns on the 2nd Embodiment of this invention is demonstrated with reference to drawings. In the manufacturing method according to the present embodiment, unlike the first embodiment, the energy of the light beam is reduced in the powder layer formed in the vicinity of the region where the drilling of the modeling plate is scheduled after modeling. Then, irradiation is performed to form a low-density sintered hardened layer. Fig.7 (a) shows the cross section of the three-dimensional shaped molded object shape | molded by the manufacturing method in this embodiment. Of the joint between the modeling plate 3 and the three-dimensional modeled article 8, the vicinity of the area where the drilling process after modeling is planned is irradiated with a low-energy light beam, so the hardness change is small. It becomes the hardening area E2. Since the region where the three-dimensional shaped object 8 is also bonded to the cured region E1 is irradiated with a high-energy light beam, it is a high-density shaped region 83a, but is bonded to the low-cured region E2. The region is a low density modeling region 83b.

  Table 1 shows the energy conditions, the density of the modeled object, the hardness of the cured region of the modeling plate 3, and the depth of the cured region when this light beam is performed with high energy and low energy.

Energy conditions, low energy condition the high-energy conditions to 20 J / mm ² is carried out at 5 J / mm ^2. As a result, the density of the modeled object is lower in the low energy condition than in the high energy condition, the hardness of the cured region of the modeling plate 3 is low, and the depth of the cured region is shallow. In particular, when the hardness of the hardened region is low energy, the hardness is HRC 25 to 30, which is not much different from the original hardness HRC 20 not irradiated with the light beam. FIG. 7B shows a cross section of the three-dimensional modeled object that has been modeled under such conditions when drilling is performed. Since the difference in hardness between the low-curing region E2 and other regions that are not irradiated with the light beam is small, there is little possibility that the tip of the drill F will be lost or the drill shank will be broken, and drilling can be performed easily. be able to.

  Moreover, in the manufacturing method in this embodiment, the light beam irradiation is performed on the low energy conditions about the location where intensity | strength is not required in the three-dimensional molded article 8. FIG. By irradiating under low energy conditions, the manufacturing cost can be reduced and the three-dimensional shaped article 8 can be reduced in weight.

  Next, a modification of the manufacturing method in the second embodiment will be described with reference to FIG. FIG. 8 shows a cross section during use of a three-dimensional shaped object formed by the manufacturing method of the present modification. This three-dimensional shaped article 8 is an injection mold, and an ejector pin hole 82 is formed at the center, and the ejector pin H passes through the hole. In this manufacturing method, in the second embodiment, when the three-dimensional shaped article 8 is an injection mold, and the hole 82 is a hole for an ejector pin, an area in which the drilling process is scheduled is performed. After forming the low density modeling region 83b in the vicinity, there is a step of modeling the path 84 that connects the hole 82 and the outside of the three-dimensional modeled article 8 by the low density modeling region 83b. Since the low density modeling region 83b has a low density, gas can pass therethrough.

  When using the injection molding die of the three-dimensional shaped object 8, when ejecting the ejector pin H at the time of releasing the molded article, gas is blown from the outside of the three-dimensional shaped object 8 through the path 84 to thereby eject the ejector. The slidability of the pin H is improved, the mold release becomes smooth, the molding cycle time can be shortened, and the molding quality can be improved. Further, the path 84 may be formed at a position away from the modeling plate 3 without being continuously formed on the modeling plate 3. The position of the path 84 can be freely designed.

(Third embodiment)
A method for manufacturing a three-dimensional shaped object according to the third embodiment of the present invention will be described. In the manufacturing method according to the present embodiment, the material of the modeling plate is different from that of the first embodiment, and a light beam is also applied to a region where a drilling process of the modeling plate is scheduled. Of the plate for modeling, at least a region where drilling is scheduled after the three-dimensional shape modeling is made of a material that hardly undergoes a change in hardness due to light beam irradiation.

  The material that does not easily change in hardness due to light beam irradiation described above is not limited to any material as long as the change in hardness is not likely to occur. In particular, the molded object is an injection mold, and the modeling plate is also a part of the mold. When used as a part, in addition to the modeling plate itself having high strength, it is important that the adhesion with the modeled object, weldability, mechanical characteristics, and thermal characteristics are close. In particular, since the joint surface is a welded structure in which the modeled object and the modeling plate are alloyed, if the modeled object is iron-based, it is desirable to use the same kind of material, for example, the modeling plate is also iron-based. In the case of this embodiment, for example, pre-hardened steel that has been heat-treated in advance by a steel manufacturer, or hot tool steel such as JIS-SKD61 steel that has been heat-treated and tempered to a hardness of about HRC 40, or JIS- A high speed tool steel such as SKH51 steel is desirable.

  Since these materials are cured by heat treatment in advance, their hardness changes only slightly even when irradiated with a light beam. Accordingly, the hardness difference between the region irradiated with the light beam and the region not irradiated is small in the region where the forming plate is drilled, so that the cutting edge of the drill F is lost or the drill shank is broken. There is little fear, and drilling after modeling can be easily performed. Further, in the modeling plate, an area formed of a material that hardly undergoes a change in hardness due to light beam irradiation is not limited to an area in which drilling is performed after modeling, for example, machining such as turning or cutting is performed. It may be an area.

  In addition, the irradiation of the light beam to the region where the modeling plate is scheduled to be punched may be performed with reduced energy or may not be performed. Since the hardness difference in the modeling plate is further reduced, drilling can be easily performed.

  In addition, this invention is not restricted to the structure of the said various embodiment, A various deformation | transformation is possible in the range which does not change the meaning of invention. For example, the composition of the metal powder and the material of the modeling plate are not limited to the configurations of the various embodiments.

The perspective view of the metal stereolithography processing machine used for the manufacturing method which concerns on the 1st Embodiment of this invention. The flowchart of the manufacturing method. (A) thru | or (e) is a figure explaining the manufacturing method in time series. The perspective view of the three-dimensional shape modeling thing modeled by the manufacturing method. (A) is a perspective view of a product model to be manufactured by the manufacturing method, (b) is a diagram showing a horizontal slice surface of the product model. (A) is a cross-sectional view of a three-dimensional shaped object by a conventional manufacturing method, (b) is a cross-sectional view when drilling a three-dimensional shaped object by the same manufacturing method, and (c) is a first embodiment. Sectional drawing of the three-dimensional shape molded article by the manufacturing method which concerns on a form, (d) is sectional drawing when performing a punching process to the three-dimensional shape molded article by the manufacturing method. (A) is sectional drawing of the three-dimensional shape molded article by the manufacturing method which concerns on the 2nd Embodiment of this invention, (b) is sectional drawing when drilling to the three-dimensional shape molded article by the manufacturing method. Sectional drawing at the time of use of the three-dimensional shape molded article by the manufacturing method which concerns on the modification of 2nd Embodiment.

Explanation of symbols

2 Metal powder 21 Powder layer 3 Modeling plate 8 Three-dimensional modeled object 8a to 8f Sintered hardened layer 84 Path L Light beam H Ejector pin

Claims (3)

A powder forming step of forming a powder layer by supplying metal powder to a modeling plate on which a three-dimensional shaped object is modeled, and irradiating the powder layer with a light beam to melt the powder layer to form a sintered hardened layer In the manufacturing method of a three-dimensional shaped object, comprising the irradiation step to form, and laminating the sintered hardened layer by repeating the irradiation step and the powder layer forming step, to form a three-dimensional shape object,
During the irradiation step, machining is scheduled for the energy of the light beam to be irradiated to the powder layer formed in the vicinity of the region where predetermined machining is scheduled after the three-dimensional shape modeling of the modeling plate. A method for producing a three-dimensional shaped article characterized by forming a low-density sintered hardened layer with a smaller density than the light beam applied to the powder layer in the unoccupied region. Of the plate for modeling, at least a region where predetermined machining is scheduled after three-dimensional shape modeling is made of a material that is hardened by heat treatment in advance and hardly changes in hardness due to light beam irradiation. The method for producing a three-dimensional shaped object according to claim 1 , wherein: The three-dimensional shaped object is an injection mold,
If the predetermined machining is a hole for an ejector pin of a mold, a path for blowing gas into the processed hole when the ejector pin slides at the time of mold release in injection molding is formed in a three-dimensional shaped object. Having the step of shaping in the injection process,
Shaping of the path, the three-dimensionally shaped object according to claim 1, characterized in that it is performed by by reducing the irradiation energy of the light beam in said injection step to form a sintered cured layer of low density Production method.

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