JP6866491B2 - Manufacturing method of titanium or titanium alloy green compact - Google Patents

Description

The present invention relates to a method for producing a titanium or titanium alloy green compact.

Titanium and titanium alloys have excellent mechanical properties, but are difficult to process, and complex shaped products have traditionally been manufactured by cutting. However, in the case of manufacturing by cutting, there is a problem that the yield is low and the product unit price becomes very high.

As one of the methods for solving the above problems, a method for producing titanium and titanium alloy green compacts by using a raw powder mixing method is known. In the raw powder mixing method, pure titanium powder and powder for adding alloying elements are mixed at a predetermined ratio, filled in a mold, compacted at room temperature, and then sintered or cold isotropic press (CIP). ) This is a processing method for performing processing and the like.

For example, in Japanese Patent Application Laid-Open No. 7-90313, a powder molding mold is produced by a blow molding method using a thermoplastic resin, the powder molding mold is filled with titanium powder, and the mold is molded by a hydrostatic molding press. This describes a method for producing a molded article of titanium powder. Japanese Unexamined Patent Publication No. 2010-188711 describes a method for producing a bottomed tubular container in which a bottomed tubular container is stretch-blow molded from a preform made of a thermoplastic resin.

Japanese Unexamined Patent Publication No. 7-90313 JP-A-2010-188711

However, in the method of forming a molded product by blow molding a thermoplastic resin as exemplified in Patent Documents 1 and 2, a high-density molded product without cracking can be obtained, but the thickness accuracy is difficult to obtain. Therefore, the titanium or titanium alloy green compact produced by using the molded product produced by blow molding tends to have a deviation in external dimensions. In order to improve the accuracy of the external dimensions, there is a method of using a metal mold or the like, but it is expensive and it becomes difficult to manufacture a complicated shape.

In view of the above problems, the present invention provides a method for producing titanium or titanium alloy green compact, which has high accuracy in external dimensions and can more economically manufacture titanium or titanium alloy green compact having a complicated shape. To do.

As a result of diligent studies, the present inventor has found that it is useful to use a CIP molding mold having a predetermined thickness range and thickness accuracy using a thermoplastic resin having predetermined characteristics. Obtained.

The present invention, which was completed based on the above findings, is a method for producing a titanium or titanium alloy green compact obtained by using a cold isotropic press to obtain a titanium or titanium alloy green compact having a relative density of 80% or more. It is represented by (maximum value-minimum value) / (maximum value + minimum value) when the thickness is 0.5 to 1.5 mm and the thickness of any 10 points in the longitudinal direction of the mold is measured. It is made of a thermoplastic resin having a mold thickness error range index α of 0 to 0.05, a compressive modulus of 800 MPa to 2100 MPa, and a shore D hardness of 78 to 85. A method for producing a titanium or titanium alloy green compact is provided, which comprises using a CIP molding mold having the above.

In one embodiment of the method for producing a titanium or titanium alloy green compact according to the present invention, the CIP molding mold is continuous with a large diameter portion and a large diameter portion, and the cross-sectional area of the horizontal cross section is smaller than that of the large diameter portion. A small diameter portion is provided at least, and the ratio D (minimum diameter of the small diameter portion / maximum diameter of the large diameter portion) of the minimum diameter of the small diameter portion to the maximum diameter of the large diameter portion in the horizontal cross section is 0.5 or more and less than 0.8. ..

In another embodiment of the method for producing a titanium or titanium alloy green compact according to the present invention, in the CIP molding mold, the outer surface of the small diameter portion is inclined with respect to the outer surface of the large diameter portion, and the large diameter portion has a large diameter portion. The angle θ formed by the straight line extending from the end of the outer side surface in the extending direction of the outer surface of the large diameter portion and the outer surface of the small diameter portion is 10 degrees or more and less than 60 degrees.

In yet another embodiment, the method for producing a titanium or titanium alloy green compact according to the present invention includes producing a mold for CIP molding using a 3D printer device.

In yet another embodiment, the method for producing a titanium or titanium alloy green compact according to the present invention includes producing a mold for CIP molding using a 3D printer device using a material extrusion method.

A method for producing a titanium or titanium alloy green compact according to the present invention includes, in yet another embodiment, producing a mold for CIP molding using a 3D printer device using a material injection method.

In still another embodiment of the method for producing a titanium or titanium alloy green compact according to the present invention, 80 to 100% by mass of pure titanium powder having an average particle size of 30 μm or more and less than 100 μm is filled in the cavity of a CIP molding mold. Including doing.

In still another embodiment, the method for producing a titanium or titanium alloy green compact according to the present invention comprises a pure titanium powder having an average particle size of 30 μm or more and less than 100 μm, and an alloy element powder or a mother alloy having an average particle size of 5 μm or more and less than 50 μm. It includes filling 1 to 20% by mass of the powder into the cavity of the CIP molding mold.

According to the present invention, it is possible to provide a method for producing titanium or titanium alloy green compact, which has high accuracy of external dimensions and can more economically manufacture titanium or titanium alloy green compact having a complicated shape.

It is sectional drawing which shows an example of the CIP molding mold which concerns on embodiment of this invention, and the measurement position (arbitrary 10 points) of the thickness of the CIP molding mold which is an example. It is explanatory drawing explaining the inclination angle θ of the large-diameter part and the small-diameter part of the mold for CIP molding which concerns on embodiment of this invention, and FIG. (B) is an example in which the small diameter portion has a curved slope.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention describes the structure, arrangement, etc. of the components as follows. It is not specific.

The method for producing a titanium or titanium alloy green compact according to an embodiment of the present invention is to obtain a titanium or titanium alloy green compact having a relative density of 80% or more by using a cold isotropic press (CIP). It is a method for producing an alloy green compact, and for example, a CIP forming mold 1 having a powder supply port 2 and a powder filling cavity 3 as illustrated in FIG. 1 can be used.

In order to produce titanium or titanium alloy green compact having a high accuracy of external dimensions and having a complicated shape, the material of the CIP molding mold 1, the compressive modulus, and the shore D are related to the manufacturing process of the CIP treatment. It is necessary to adjust the hardness to an appropriate range and to increase the thickness and thickness accuracy of the CIP molding mold 1.

Specifically, the CIP molding mold 1 according to the present embodiment needs to have a thickness of 0.5 to 1.5 mm. If the thickness is less than 0.5 mm, the weight of the filling powder may deform the CIP molding mold 1 and reduce the dimensional accuracy. On the other hand, if the thickness is made larger than 1.5 mm, the springback force of the CIP forming mold 1 at the time of CIP unloading becomes larger than the green compact strength, and the green compact may break.

Regarding the dimensional accuracy of the thickness, the mold thickness error range index α expressed by (maximum value-minimum value) / (maximum value + minimum value) when the thickness of any 10 points in the longitudinal direction of the mold is measured. Is preferably 0 to 0.05. When evaluating the dimensional accuracy of the thickness, if the thickness measurement points are locally biased, it may not be possible to appropriately evaluate the variation in the thickness of the CIP molding mold 1 as a whole. Therefore, in the present embodiment, as a measurement point of "arbitrary 10 points of thickness", it means a place where the longest surface of the CIP molding mold 1 is divided into 10 equal parts. For example, as shown in FIG. 1, the CIP molding mold 1 is allowed to stand on the horizontal plane so that the longitudinal direction along the maximum length of the CIP molding mold 1 faces the direction perpendicular to the horizontal plane, and the direction perpendicular to the horizontal plane. The thickness at each position (1 to 10) obtained by dividing the CIP molding mold 1 into 10 equal parts can be measured.

That is, as shown in FIG. 1, the “mold thickness error range index α” is an arbitrary height of the CIP molding mold 1 when the CIP molding mold 1 is divided into 10 equal parts along the longitudinal direction of the CIP molding mold 1. It refers to the error range index evaluated by measuring the thickness of the measurement point at the position and using the maximum and minimum values. The thickness can be measured, for example, by using a digital caliper or the like for each measurement point.

When the mold thickness error range index α becomes larger than 0.05, the accuracy of the external dimensions of the titanium or titanium alloy green compact produced by using the CIP molding mold 1 deteriorates, and the springback force is controlled. Becomes difficult and causes breakage. The mold thickness error range index α is preferably 0.03 or less, more preferably 0.01 or less, and further preferably 0.005 or less.

When the target thickness of the CIP molding mold 1, that is, the thickness data of the CIP molding mold 1 at the time of manufacturing is known, the dimensional accuracy of the CIP molding mold 1 is evaluated by the mold thickness error range index β. You can also. The mold thickness error range index β is a measurement point at an arbitrary position at each height when the mold thickness error range index β is divided into 10 equal parts along the longitudinal direction of the CIP molding mold 1 in the same manner as the measurement of the mold thickness error range index α. Refers to "(maximum value-minimum value) / target thickness" when the thickness of each is measured. As the target thickness, for example, the thickness of the three-dimensional CAD source data at the time of molding the CIP molding mold 1 can be used.

When the mold thickness error range index β becomes larger than 0.5, the accuracy of the external dimensions of the titanium or titanium alloy green compact produced by using the CIP molding mold 1 deteriorates, and the springback force is controlled. Becomes difficult and causes breakage. An error with a mold thickness error range index β of 0.5 or less does not affect the physical properties of the CIP molding mold 1. The mold thickness error range index β is preferably 0.3 or less, more preferably 0.1 or less, still more preferably 0.06 or less.

Alternatively, the absolute value of any 10 points (thickness / target thickness × 100-100) at each height when the CIP molding mold 1 is divided into 10 equal parts along the longitudinal direction of the CIP molding mold 1. The average value of is also evaluated as the mold thickness error range index γ. The mold thickness error range index γ is preferably less than 1.5, more preferably 1.0 or less, still more preferably 0.5 or less.

As the material used for the CIP molding mold 1, a thermoplastic resin is preferable, and for example, an acrylic resin, a polylactic acid (PLA) resin, and the like can be preferably used. The compressive elastic modulus of the thermoplastic resin material is preferably 800 MPa to 2100 MPa. If the compressive elastic modulus is less than 800 MPa, the springback of the CIP forming mold 1 at the time of CIP unloading becomes large, which may lead to breakage of the green compact. Further, if the compressive elastic modulus is too low, the rigidity of the CIP molding mold 1 is insufficient, the CIP molding mold 1 is deformed by the weight of the filling powder, and the dimensional accuracy of the CIP molded product may be significantly lowered.

On the other hand, when the compressive elastic modulus is made larger than 2100 MPa, the rigidity of the CIP molding mold 1 becomes high, the load is not sufficiently transmitted to the internal powder during CIP processing pressurization, and the titanium or titanium alloy green compact having a relative density of 80% or more. Cannot be obtained. The compressive elastic modulus of the thermoplastic resin used in the CIP molding mold 1 is more preferably 1000 MPa to 1900 MPa, still more preferably 1500 MPa to 1900 MPa. The compressive modulus can be measured by a test method conforming to JIS K7181 (2011).

The Shore D hardness of the thermoplastic resin used for the CIP molding mold 1 is preferably 78 to 85, more preferably 80 to 83. When the shore D hardness is less than 78, the CIP molding mold 1 is deformed by the weight of the filling powder, and the dimensional accuracy is lowered. When the shore D hardness is made larger than 85, the rigidity of the CIP forming mold 1 becomes high, the load is not sufficiently transmitted to the internal powder during CIP processing pressurization, and a titanium or titanium alloy green compact having a relative density of 80% or more is obtained. Can't. Shore D hardness can be measured by a test method conforming to JIS K7215 (1986).

As shown in FIG. 1, the CIP molding mold 1 is continuous with the large diameter portion 11 and the large diameter portion 11, and has a smaller horizontal cross-sectional area than the large diameter portion 11 from the small diameter portion 12 and the small diameter portion 12. Also includes a large diameter portion 13 having a large horizontal cross-sectional area and continuous with the small diameter portion 12, and a top portion 14 continuous with the large diameter portion 13 and having a powder supply port 2 at the top.

The small diameter portion 12 has a constriction so that the horizontal cross-sectional area gradually decreases from the bottom to the top and the horizontal cross-sectional area gradually increases from the middle portion of the small diameter portion 12 toward the large diameter portion 13. It can have a shape to have.

The large diameter portions 11 and 13 may have a polygonal horizontal cross section, or may have a circular or elliptical horizontal cross section, and may be appropriately changed according to the intended use, and have a specific shape. Is not particularly limited. _{The ratio D of the minimum diameter D 12} of the small diameter portion 12 to _{the maximum diameter D 11 of the large diameter portions 11 and} 13 in the horizontal cross section (small diameter portion minimum diameter D ₁₂ / large diameter portion maximum diameter D ₁₁ ) is 0.5 or more. It is less than 8. The shapes of the large diameter portions 11 and 13 and the small diameter portions 12 are preferably substantially similar to each other in horizontal cross sections, but may have different shapes.

As shown in the enlarged view of FIG. 2A, in the CIP molding mold 1, the outer surface 121 of the small diameter portion 12 is inclined with respect to the outer surface 111 of the large diameter portion 11. An angle θ formed by a straight line X extending in the extending direction of the outer surface 111 of the large diameter portion 11 from the end 112 of the outer surface 111 of the large diameter portion 11 and the outer surface 121 of the small diameter portion 12 (example of FIG. 2A). Then, the angle θ) formed by the outer surface 121 of the small diameter portion 12 when measured counterclockwise from the straight line X is 10 degrees or more and less than 60 degrees. When the outer surface 121 of the small diameter portion 12 has a curved surface, as shown in FIG. 2B, the _{position where the minimum diameter D 12} is obtained in the horizontal cross section of the small diameter portion 12 and the end portion 112 of the large diameter portion 11 The angle θ formed by the straight line Y and the straight line X (that is, the angle formed by the straight line Y when measured counterclockwise from the straight line X with respect to the straight line X) is 10 degrees or more and less than 60 degrees.

The CIP molding mold 1 having a complicated shape as shown in FIGS. 1 and 2 (a) and 2 (b) can be manufactured by using a 3D printer device. As a result, the thickness can be made uniform and the dimensional accuracy can be improved as compared with the case where the mold is formed by blow molding as in the conventional case. Further, since it is not necessary to manufacture a mold or the like when manufacturing the mold, the CIP molding mold 1 having a more economically complicated shape can be manufactured so as to have high dimensional accuracy.

A general-purpose device can be used as the 3D printer device, but it is preferable to use a 3D printer device using a material extrusion method or a 3D printer device using a material injection method.

Titanium according to the present embodiment is formed by filling the cavity 3 in the CIP molding mold 1 according to the present embodiment with pure titanium powder or pure titanium powder and alloy element powder or mother alloy powder and performing CIP treatment. Alternatively, a titanium alloy green compact can be obtained. Here, the alloy element powder is a powder of a single element such as Al powder or V powder, and the mother alloy powder is a powder containing a plurality of elements.

As the filler, for example, by filling 80 to 100% by mass of pure titanium powder having an average particle size of 30 μm or more and less than 100 μm into the cavity of the CIP molding mold, a titanium or titanium alloy green compact having a relative density of 80% or more is filled. Is obtained. Alternatively, 1 to 20% by mass of pure titanium powder having an average particle size of 30 μm or more and less than 100 μm and alloy element powder or mother alloy powder having an average particle size of 5 μm or more and less than 50 μm are filled in the cavity 3 of the CIP molding mold 1. By carrying out the CIP treatment, a titanium or titanium alloy green compact having a relative density of 80% or more can be obtained. The average particle size refers to the value of the particle size D50 (median diameter) of the particle size distribution (volume basis) obtained by the laser diffraction / scattering method. The powder filling and CIP treatment can be carried out under generally well-known conditions. In the present embodiment, "pure titanium" means industrial pure titanium satisfying the composition specified in JIS Class 2. The main alloy systems used for titanium alloy powders are Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-4Zr-6Mo, Ti. -10V-2Fe-3Al and the like can be mentioned.

According to the titanium or titanium alloy green compact according to the embodiment of the present invention, a mold for CIP molding in which the thickness and thickness accuracy are controlled by using a predetermined thermoplastic resin using a 3D printer. By obtaining 1 and performing a CIP treatment using this, titanium or a titanium alloy green compact having a high accuracy in external dimensions and a complicated shape can be produced more economically.

Examples and comparative examples of the present invention will be described below, but it goes without saying that the present invention is not limited to the following examples.

For CIP molding with a 3D printer using three types of resin (PLA resin, acrylic resin, silicon resin) based on the 3D data of the CIP molding mold whose thickness was adjusted between 0.5 and 1.75 mm. A mold was made. The mold for CIP molding using PLA resin was produced by a material extrusion method using a 3D printer device Kuhoria manufactured by Kuho Metal Manufacturing Co., Ltd. A mold for CIP molding using an acrylic resin was produced by a material injection method using a 3D printer device ProJet3600MAX manufactured by 3D Systems. The silicon resin material was produced by a material injection method using a 3D printer device AGILISTA-3200 manufactured by KEYENCE. The ratio D of the large diameter part to the small diameter part of the CIP molding mold is set to 0.6, and the angle θ between the large outer diameter and the small outer diameter is set to 27 degrees to obtain the CIP molding mold having the shape shown in FIG. Made.

The cavity in the prepared CIP molding mold was filled with pure titanium powder TC-150 (particle size width 45-150 μm, average particle size 90 μm) manufactured by Toho Tech, and CIP treatment was performed. For the CIP treatment, a cold hydrostatic pressure forming apparatus CL4-22-60 manufactured by Nikkiso Co., Ltd. was used.

The cavity in the prepared CIP molding mold is filled with pure titanium powder, tapped, sealed with vinyl tape, vacuum packed, and the vacuum packed pure titanium powder filled product is set in a cold hydrostatic molding device. And pressurized. When it reached about 300 MPa, it was held for 1 minute and then decompressed, and the titanium powder-filled product was taken out from the cold hydrostatic molding apparatus. The obtained molded product was heated at atmospheric pressure and 130 ° C. for 15 minutes, and the softened CIP molding mold was removed using a cutter, nippers, or the like to obtain a green compact.

The mold thickness error range indices α, β, γ, compressive elastic modulus, shore D hardness, and powder density (relative density) were measured for the CIP molding molds produced using each material and each device. As the target thickness, the thickness at the time of creating 3D data was used. The CIP molding mold 1 was divided into 10 equal parts in the longitudinal direction (12 mm intervals in this example), and the thickness of 10 points was measured with a tickness gauge. The compressive elastic modulus was calculated from the measurement results carried out in accordance with JIS K7181 (2011). Shore D hardness was measured according to JIS K7215 (1986). The green compact density was calculated from the density / theoretical density 4.51 / cm ^{3 × 100 obtained by the Archimedes method.} Furthermore, the presence or absence of breakage of the obtained green compact was observed. The results are shown in Table 1.

In Comparative Examples 1 and 2 in which a mold for CIP molding having a thickness of 1.75 mm, which is outside the range of 0.5 to 1.5 mm, was produced, the mold could be produced, but the pressure of titanium or a titanium alloy was obtained. The powder was broken and the desired green compact could not be produced. In Comparative Examples 3 and 4 using a silicone resin whose compressive elastic modulus and shore D hardness were outside the range of the present invention, it was not possible to produce a mold for CIP molding. In Comparative Example 5, a mold could be produced, but the shape after powder filling could not be maintained during the CIP treatment due to insufficient strength. On the other hand, in Examples 1 to 4, it was possible to prepare a green compact having a relative density of 80% or more and no breakage.

1 ... CIP molding mold 2 ... Powder supply port 3 ... Cavity 11 ... Large diameter part 12 ... Small diameter part 13 ... Large diameter part 14 ... Top 111, 121 ... Outer surface 112 ... End

Claims (7)

A method for producing a titanium or titanium alloy green compact obtained by using a cold isotropic press to obtain a titanium or titanium alloy green compact having a relative density of 80% or more.
Mold thickness represented by (maximum value-minimum value) / (maximum value + minimum value) when the thickness is 0.5 to 1.5 mm and the thickness of any 10 points in the longitudinal direction of the mold is measured. error range exponent α is 0 to 0.05, the compression modulus 800MPa～2100MPa, Shore D hardness is a thermoplastic resin of 78 to 85, possess a cavity of a powder supply port and the powder filling A method for producing a titanium or titanium alloy green compact, which comprises using a CIP molding mold produced by using a 3D printer device. A method for producing a titanium or titanium alloy green compact obtained by using a cold isotropic press to obtain a titanium or titanium alloy green compact having a relative density of 80% or more.
Mold thickness represented by (maximum value-minimum value) / (maximum value + minimum value) when the thickness is 0.5 to 1.5 mm and the thickness of any 10 points in the longitudinal direction of the mold is measured. It is made of a thermoplastic resin having an error range index α of 0 to 0.05, a compressive modulus of 800 MPa to 2100 MPa, and a shore D hardness of 78 to 85, and has a powder supply port and a cavity for powder filling. , A method for producing a titanium or titanium alloy green compact, which comprises using a CIP molding mold produced by using a 3D printer apparatus using a material extrusion method . A method for producing a titanium or titanium alloy green compact obtained by using a cold isotropic press to obtain a titanium or titanium alloy green compact having a relative density of 80% or more.
Mold thickness represented by (maximum value-minimum value) / (maximum value + minimum value) when the thickness is 0.5 to 1.5 mm and the thickness of any 10 points in the longitudinal direction of the mold is measured. It is made of a thermoplastic resin having an error range index α of 0 to 0.05, a compressive modulus of 800 MPa to 2100 MPa, and a shore D hardness of 78 to 85, and has a powder supply port and a cavity for powder filling. , A method for producing a titanium or titanium alloy green compact, which comprises using a CIP molding mold produced by using a 3D printer apparatus using a material injection method . The CIP molding mold includes at least a large-diameter portion and a small-diameter portion that is continuous with the large-diameter portion and has a smaller cross-sectional area in the horizontal cross section than the large-diameter portion, and the maximum of the large-diameter portion in the horizontal cross section. The invention according to any one of claims 1 to 3, wherein the ratio D of the minimum diameter of the small diameter portion to the diameter (minimum diameter of the small diameter portion / maximum diameter of the large diameter portion) is 0.5 or more and less than 0.8. Method for producing titanium or titanium alloy green compact. In the CIP molding mold, the outer surface of the small diameter portion is inclined with respect to the outer surface of the large diameter portion, and the outer surface of the large diameter portion extends from the end of the outer surface of the large diameter portion. The method for producing a titanium or titanium alloy green compact according to claim 4 , wherein the angle θ formed by the straight line extending in the direction and the outer surface of the small diameter portion is 10 degrees or more and less than 60 degrees. The titanium or titanium alloy according to any one of claims 1 to 5 , which comprises filling 80 to 100% by mass of pure titanium powder having an average particle size of 30 μm or more and less than 100 μm into the cavity of the CIP molding mold. Method for producing green compact. A pure titanium powder having an average particle size of 30 μm or more and less than 100 μm and an alloy element powder or a mother alloy powder having an average particle size of 5 μm or more and less than 50 μm are filled in the cavity of the CIP molding mold in an amount of 1 to 20% by mass. The method for producing a titanium or titanium alloy green compact according to any one of claims 1 to 5, which comprises.

Images