JP7249707B1 - Cemented Carbide Molded Body with Slotted Pores and Method for Manufacturing Same - Google Patents

Abstract

A novel compact made of cemented carbide and having uniform elongated through-holes is manufactured. A joining step is performed to obtain a resintered body having at least one elongated through-hole by sintering and joining a plurality of rectangular parallelepiped sintered bodies obtained by dividing the elongated through-holes in the length direction. After that, a molded body 1 made of cemented carbide and having at least one elongated through-hole 1a, 1b is produced. In the obtained molded body 1, the elongated through holes 1a and 1b have an average hole diameter of 200 μm or less, and the length of the elongated through holes 1a and 1b is 30 times or more the average hole diameter. In the longitudinal direction of the elongated through-holes 2, the pore size distribution may be 20% or less with respect to the average pore size. The parallelism of the elongated through holes 1a and 1b may be 30 μm or less. [Selection drawing] Fig. 1

Description

TECHNICAL FIELD The present invention relates to a cemented carbide compact having elongated through holes that can be used for molds and the like, and a method for producing the same.

Cemented carbide is hard and has excellent wear resistance and durability, so it is widely used as molds for various compacts. Due to recent technological innovations, along with the miniaturization of optical devices and electronic devices, the shape of molded products has increased in fine shapes, and there are also ultrafine and linear molded products. However, since cemented carbide is hard and difficult to process, a mold made of cemented carbide is not known as a mold for molding an ultra-thin and linear compact.

On the other hand, Japanese Patent Application Laid-Open No. 2022-1662 (Patent Document 1) describes a cemented carbide containing a hard phase containing tungsten carbide WC as a main component as a cemented carbide body that can be used for cutting tools, nozzles, capillaries, etc. An elongated cemented carbide body is disclosed having micropores configured and having diameters of 100 μm or less. In this document, this long cemented carbide body is formed by extruding a supply powder obtained by compacting a raw material powder containing tungsten carbide WC through a die having a tungsten wire having a diameter of 100 μm or less arranged in a passage. Obtained by sintering the article, said pores are said to be of the same diameter in the longitudinal direction.

Japanese Patent Application Laid-Open No. 2022-1662

However, Patent Document 1 does not describe the specific length of the micropores or the uniformity of their shape. Furthermore, since the long cemented carbide body described in Patent Document 1 is manufactured by extrusion molding, it is expected that the long micropores will be bent in the process of being extruded, and the straight through holes is difficult to manufacture, and the hole diameter is likely to change due to bending of the through hole during the manufacturing process. Therefore, the micropores of the long cemented carbide body of Patent Document 1 are not straight, have a large concentricity (or parallelism at the end face), and have non-uniform pore diameters. Linear molded products as electronic components that require high precision even if they are within the permissible range for applications such as cutting tools and nozzles for supplying or ejecting the described fluid, capillaries used for wire bonding, etc. It is an unacceptable range for applications such as molds for forming. In particular, for applications that require precision, in order to precisely form a fine shape, the finishing process is pore electrical discharge machining or WE electrical discharge machining (wire electrical discharge machining or wire cutting) using electrodes for through holes. electrical discharge machining) is required. In hole electric discharge machining or WE electric discharge machining, a gap (discharge allowance) is required between the electrode and the workpiece. Electrical discharge machining cannot be performed due to contact with the inner wall of the hole. Furthermore, in the manufacturing method of Patent Document 1, it is necessary to use an extruder equipped with a cylinder, which makes manufacturing difficult.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a novel compact made of cemented carbide and having uniform elongated through-holes, and a method for producing the same.

As a result of intensive studies to achieve the above object, the present inventors have found that a rectangular parallelepiped sintered body having an elongated through hole is divided into a plurality of sintered bodies having a shape that is divided across the elongated through hole in the length direction. The inventors have found that a novel molded body made of cemented carbide and having uniform fine elongated through-holes can be produced by a method of aligning and joining bodies, and completed the present invention.

That is, the manufacturing method as aspect [1] of the present invention is
A method for producing a molded body made of cemented carbide and having at least one elongated through hole, comprising:
A joining step of aligning at least one elongated groove formed on the joint surface and sintering and joining a plurality of sintered bodies to obtain a cuboid re-sintered body having at least one elongated through hole. ,
The plurality of sintered bodies have a shape obtained by dividing them by crossing the elongated through holes of the resintered rectangular parallelepiped body in the length direction.

In the aspect [2] of the present invention, in the bonding step of the aspect [1],
The rectangular parallelepiped resintered body is a resintered body in which a cross section L-shaped sintered body and a rectangular parallelepiped sintered body are positioned or fitted and sintered together,
a base having an elongated groove for forming an elongated through-hole in the bonding surface in a state in which the sintered body having an L-shaped cross section is positioned or fitted with the sintered body having a rectangular parallelepiped; and a positioning part erected from the end of the part,
The rectangular parallelepiped sintered body is formed with an elongated groove portion for forming an elongated through-hole in the bonding surface in a state of being positioned or fitted with the L-shaped cross section sintered body, and the L-shaped cross section In this aspect, the corners of the rectangular parallelepiped sintered body positioned at the corners of the positioning portion of the sintered body are chamfered to provide a gap between the corners.

Aspect [3] of the present invention is the aspect [2], wherein the parallelism of the contact surfaces of the L-shaped cross-sectional sintered body and the rectangular parallelepiped sintered body is 3 μm or less, and the L-shaped cross-section In this embodiment, the squareness of the corners of the sintered body is 3 μm or less.

In aspect [4] of the present invention, in the bonding step of aspect [1],
The re-sintered rectangular parallelepiped body includes a sintered body with an L-shaped cross section and a first sintered rectangular parallelepiped body for positioning or fitting with the sintered body with an L-shaped cross section to form an elongated hole. and at least one other rectangular parallelepiped sintered body are fitted and sintered together,
a base portion having an elongated groove for forming an elongated through-hole in the bonding surface in a state in which the sintered body having an L-shaped cross section is positioned or fitted with the first sintered body having a rectangular parallelepiped; , and a positioning portion erected from the end of the base portion, and in a state where the first rectangular parallelepiped sintered body is positioned or fitted with the L-shaped cross section sintered body, on the joint surface An elongated groove for forming an elongated through-hole is formed, and an elongated groove for forming an elongated through-hole is formed in the bonding surface in a state of being positioned or fitted with the other rectangular parallelepiped sintered body. formed,
An elongated groove portion for forming an elongated through hole is formed in the joint surface in a state where the rectangular parallelepiped sintered bodies are positioned or fitted to each other in the other rectangular parallelepiped sintered body, and the cross section is L-shaped. In this mode, the corners of the first rectangular parallelepiped sintered body positioned at the corners of the positioning portions of the sintered body are chamfered to provide a gap between the corners.

Aspect [5] of the present invention is Aspect [4], wherein parallelism of joint surfaces between the L-shaped cross-section sintered body and the first rectangular parallelepiped sintered body is 3 μm or less, and Parallelism of joint surfaces of the rectangular parallelepiped sintered body of No. 1 and the other rectangular parallelepiped sintered bodies is 3 μm or less, and parallelism of joint surfaces of the other rectangular parallelepiped sintered bodies is 3 μm or less. and the squareness of the corners of the sintered body having an L-shaped cross section is 3 μm or less.

Aspect [6] of the present invention is based on any one of Aspects [1] to [5], wherein, as a pre-process of the bonding step, elongated through-holes are formed in the plurality of sintered bodies. In this embodiment, the shaped groove is formed by grinding with an optical profiling grinder.

Aspect [7] of the present invention is any one of Aspects [2] to [6], wherein the re-sintered body obtained in the bonding step does not include elongated through-holes and has the rectangular parallelepiped shape. This embodiment includes a cutting step of cutting and removing a region including a gap formed by chamfering corners of the sintered body or the first rectangular parallelepiped sintered body.

Aspect [8] of the present invention is the electric discharge machining step of inserting a porous electrode into the elongated through-hole of the resintered body and performing electric discharge machining in any one of the above-mentioned aspects [1] to [7]. It is an embodiment further comprising

Aspect [9] of the present invention is based on Aspect [8], wherein the re-sintered body obtained in the electric discharge machining step does not contain elongated through-holes, and the rectangular parallelepiped sintered body or the first This embodiment includes a cutting step of cutting and removing a region including a gap formed by chamfering the corners of the rectangular parallelepiped sintered body.

In the present invention, as aspect [10], there is provided a cuboid formed body made of cemented carbide and having at least one elongated through-hole, wherein the elongated through-hole has an average pore size of 200 μm or less, and A rectangular parallelepiped molded body in which the length of the elongated through holes is 30 times or more the average hole diameter is also included.

Aspect [11] of the present invention is an aspect according to the aspect [10], wherein the pore size distribution in the longitudinal direction of the elongated through-holes is 20% or less with respect to the average pore size.

Aspect [12] of the present invention is an aspect in which the parallelism of the elongated through-holes is 30 μm or less in the aspect [10] or [11].

Aspect [13] of the present invention is any one of Aspects [10] to [12], wherein the opening shape of the elongated through-hole is circular, elliptical or polygonal.

Aspect [14] of the present invention is an aspect in which, in any one of Aspects [10] to [13], the opening shape of the elongated through-hole is circular.

Aspect [15] of the present invention is an aspect in which, in any one of Aspects [10] to [14], the rectangular parallelepiped molded body has a plurality of elongated through-holes extending in parallel at intervals. .

Aspect [16] of the present invention is an aspect in which, in any one of the aspects [10] to [15], the cuboid molded article is a mold.

In the specification and claims of the present application, "rectangle" means "square or rectangle".

In the present invention, a rectangular parallelepiped sintered body having an elongated through-hole is joined together with a plurality of sintered bodies having a shape divided by crossing the elongated through-hole in the length direction. It is possible to produce a novel compact having elongated through-holes that are formed and uniform and fine. Moreover, since there is no need to use a production machine such as an extruder, a compact having elongated through-holes can be easily produced. The resulting molded article has elongated through-holes with a uniform micropore size in the length direction and a high degree of parallelism, so that it can be used as a mold for electronic parts that require a precise elongated shape.

FIG. 1 is a schematic see-through perspective view showing an example of the molded article of the present invention. FIG. 2 is a schematic see-through perspective view showing another example of the molded article of the present invention. 3A and 3B are schematic end elevations for explaining a method for manufacturing the molded body of FIG. 1. FIG. FIG. 4 is a schematic see-through perspective view showing a state in which a plurality of sintered bodies are fitted in the joining step shown in FIG. 3(a). FIG. 5 is a schematic end view for explaining the method of manufacturing the compact of FIG. FIG. 6 is a schematic cross-sectional view for explaining the electric discharge machining step in the method for producing a molded article of the present invention. FIG. 7 is a photograph of the resintered body obtained in Example, which was cut by equally dividing the elongated through-holes along the length direction, and the length of the elongated through-holes in the obtained resintered body. It is an enlarged photograph of the upper end (A), the central part (B) and the lower end (C) in the vertical direction.

[Material of molding]
The cemented carbide that is the material of the compact of the present invention is not particularly limited. Typical cemented carbides include alloys containing metal carbides of Groups 4 to 6 of the periodic table. Among them, alloys containing tungsten carbide WC (tungsten carbide) (WC alloys) are widely used.

The WC-based alloy may be composed of WC, which is the main component, and a binder component that forms a liquid phase by sintering to form a binder phase.

Examples of binding components include periodic table 8-10 group metals such as manganese Mn, iron Fe, cobalt Co, and nickel Ni. These binding components can be used alone or in combination of two or more. Among these, cobalt Co and/or nickel Ni are preferred, and cobalt Co is particularly preferred.

The proportion of the binding component (particularly Co) may be 40 parts by weight or less, preferably 0.5 to 35 parts by weight, more preferably 1 to 30 parts by weight, with respect to 100 parts by weight of tungsten carbide.

The WC-based alloy may further contain metal carbides (other metal carbides) other than the main component. Other metal carbides include, for example, titanium carbide TiC, niobium carbide NbC, tantalum carbide TaC, chromium carbide Cr ₃ C ₂ and the like. These other metal carbides can be used alone or in combination of two or more. Among these, TiC, TaC and Cr ₃ C ₂ are preferred.

The WC-based alloy may further contain an elemental metal (another elemental metal) other than the binding component. Examples of other metal elements include titanium Ti, zirconium Zr, vanadium V, niobium Nb, tantalum Ta, chromium Cr, molybdenum Mo, tungsten W, and rhenium Re. These other metal simple substances can be used individually or in combination of 2 or more types. Of these, V and/or Cr are preferred.

The ratio of the other metal simple substance may be 5 parts by mass or less, preferably 0.1 to 3 parts by mass, more preferably 0.2 to 2 parts by mass with respect to 100 parts by mass of the entire WC alloy. .

The WC-based alloy may further contain a carbon source C (such as carbon black), and may contain components that are unavoidably mixed.

WC-based alloys include, for example, WC-Co-based alloys, WC-TiC-Co-based alloys, WC-TaC-Co-based alloys, WC-TiC-TaC-Co-based alloys, WC-Ni-based alloys, WC-Ni- Cr system alloy etc. are mentioned. Among these, WC—Co alloys are widely used.

[Shape of compact]
The shape of the molded article of the present invention is not particularly limited as long as it has elongated through holes with an average pore diameter of 200 μm or less and a length of 30 times or more the average pore diameter. Although it may have a polygonal columnar shape or the like, a rectangular parallelepiped shape is preferable from the viewpoint of productivity because the re-sintered body can be obtained in a rectangular parallelepiped shape. The detailed shape of the molded article of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic see-through perspective view of an example of the molded article of the present invention. This molded body 1 has two elongated through holes 1a and 1b extending in parallel with a space therebetween, and the surface shape of the end faces of these elongated through holes 1a and 1b is a rectangular parallelepiped. . Furthermore, the elongated through holes 1a and 1b have a circular cross-sectional shape perpendicular to the length direction.

FIG. 2 is a schematic see-through perspective view of another example of the molded article of the present invention. The molded body 2 has six elongated through holes 2a, 2b, 2c, 2d, 2e, and 2f extending in parallel at intervals. is a rectangular parallelepiped. Furthermore, among the elongated through-holes, the elongated through-holes 2a and 2b are the first hole row, the elongated through-holes 2c and 2d are the second hole row, and the elongated through-holes 2e and 2f are the second row. It is arranged as three rows of holes. On the end face, the arrangement direction of the first to third hole rows is parallel to the long side of the rectangle on the end face, and the first to third hole rows are arranged at equal intervals in the short side direction. Further, the elongated through holes 2a, 2c and 2e are arranged as the fourth hole row, and the elongated through holes 2b, 2d and 2f are arranged as the fifth hole row. The orientation direction of the fourth hole-row and the fifth hole-row is a direction that is inclined with respect to one side of the rectangle on the end face, and the fourth hole-row and the fifth hole-row are arranged with a space therebetween. ing.

The shape of the rectangular parallelepiped molded body has a uniform hole diameter in the length direction, a low numerical value of parallelism, and an elongated through hole close to a straight line (hereinafter sometimes referred to as a "uniform and straight elongated through hole"). ) is easy to form, it is important that the corners of the re-sintered body are right-angled, and the surface shape may be rectangular. Therefore, the surface shape is not limited to the rectangular shape shown in FIGS. 1 and 2, and may be a square shape.

The number of elongated through-holes can be selected according to the application and is not particularly limited. , about 2 to 10.

The formation position of the elongated through-holes can be appropriately selected depending on the application and the number of holes. When a plurality of elongated through-holes are formed, they are preferably arranged at predetermined intervals, particularly regularly arranged at equal intervals.

The cross-sectional shape of the elongated through-hole perpendicular to the length direction may be an anisotropic shape such as an elliptical shape or a rectangular shape. Shapes are particularly preferred.

The elongated through-holes are very fine through-holes, and the average pore size is 200 μm or less, preferably 100 μm or less. Specifically, the average pore diameter of the elongated through holes can be selected from the range of about 1 to 150 μm, for example, 10 to 130 μm, preferably 20 to 120 μm, more preferably 30 to 110 μm, more preferably 50 to 100 μm, most preferably 50 to 100 μm. It is preferably 70 to 90 μm. If the average pore size is too small, it may be difficult to form uniform and straight (linear) elongated through-holes.

In addition, in the present specification and claims, the average hole diameter of elongated through holes can be measured using an optical image measuring device (smart scope) or the like. The average pore diameter can be obtained by averaging the pore diameters of the upper and lower surfaces, but each pore diameter means the maximum diameter, and in the case of a circular shape, it is the diameter, and in the case of a polygonal or anisotropic shape, it means the major axis.

Since the elongated through-holes are elongated, they have a large aspect ratio, which is the ratio of the length to the hole diameter. The length of the elongated through-holes should be at least 30 times the average pore diameter, preferably at least 100 times. Specifically, the length of the elongated through holes is 30 to 1000 times the average pore diameter, preferably 50 to 800 times, more preferably 70 to 500 times, more preferably 80 to 300 times, most preferably 100 to 100 times. 200 times. If the aspect ratio is too large, there is a risk that the productivity of the molded product will decrease.

The elongated through-holes have a high uniformity of pore size, and in the length direction of the elongated through-holes, the pore size dispersion is, for example, 20% or less, preferably 15% or less, and more preferably 10% with respect to the average pore diameter. or less, more preferably 5% or less, and most preferably 3% or less.

In addition, in the present specification and claims, the pore size distribution is represented by the following formula.

Dispersion of pore diameters={[maximum value of difference (absolute value) between average pore diameter and maximum pore diameter or minimum pore diameter]/average pore diameter}×100 (%).

The elongated through-hole has little undulation and deformation (bending), is straight, and has a high straightness. The parallelism with respect to the end faces of the elongated through holes is, for example, 30 μm or less, preferably 20 μm or less, more preferably 10 μm or less, more preferably 5 μm or less, and most preferably 3 μm or less.

In this specification and the scope of claims, the parallelism of the elongated through-holes is determined in accordance with JIS B 0621. can be measured using the end face of

[Joining process]
In the method for producing a molded body of the present invention, a plurality of sintered bodies are sinter-bonded by aligning at least one elongated groove formed on a bonding surface with each other, and forming a rectangular parallelepiped having at least one elongated through hole. It includes a joining step to obtain a resintered body. In the present invention, in the joining step, a plurality of sintered bodies having a shape obtained by dividing the elongated through-holes of the cuboid re-sintered body in the length direction are aligned and joined to achieve a uniform and straight shape. Elongated through holes can be easily formed.

(Raw material powder)
The raw material powder can be appropriately selected according to the type of cemented carbide, and usually the constituent components of the cemented carbide are used in the form of particles. In the WC-based alloy, in addition to binding component particles, other metal carbide particles and other metal particles are used as raw material powders as necessary.

The average particle size of WC particles is, for example, 0.1 to 15 μm, preferably 0.12 to 12 μm, more preferably 0.2 to 10 μm.

The average particle size of the binder component particles (especially Co particles) is not particularly limited because it melts to form a binder phase, but is for example 0.1 to 5 μm, preferably 0.5 to 3 μm, more preferably 1 to 5 μm. 2.5 μm.

The average particle size of the other metal carbide particles and the other metal particles is, for example, 0.1 to 5 μm, preferably 0.5 to 3 μm, more preferably 1 to 2.5 μm.

The amount of raw material powder used for these WC-based alloys is the same as the ratio of the constituent components in the aforementioned cemented carbide.

In powder compacting (compression molding), a binder may be blended in addition to these raw material powders. As the binder, a binder that can be removed by heating during the sintering process is preferred. Such binders include, for example, straight or branched chain aliphatic hydrocarbons such as paraffin, wax or wax, polyethylene glycol, and the like. These binders may be in particulate form. Additionally, these binders may be formulated with alcohols such as ethanol and/or benzines.

The proportion of the binder may be 20 parts by weight or less, preferably 0.1 to 10 parts by weight, more preferably 0.2 to 7 parts by weight, per 100 parts by weight of the raw material powder.

(Joining step of compact shown in FIG. 1)
A process of joining the compacts shown in FIG. 1, which is an example of the joining process, will be described with reference to FIG.

3A and 3B are schematic end views for explaining the method of manufacturing the compact shown in FIG. Fig. 3(b) is a schematic end view for comparison with the molded body [Fig. 3(b)]. Note that FIG. 3 is a schematic diagram in which the hole diameters of the elongated through-holes are enlarged compared to FIG. 1 in order to visually facilitate understanding of the positional relationship of the elongated through-holes. Moreover, FIG. 4 is a schematic see-through perspective view showing a state in which a plurality of sintered bodies are fitted in the joining step shown in FIG. 3(a).

The plurality of sintered bodies joined in the joining step in FIGS. 3 and 4 correspond to the shape obtained by dividing the rectangular parallelepiped compact 1 shown in FIG. 3(b), as shown in FIG. 3(a). A sintered body 12 having an L-shaped cross section and a sintered body 13 having an L-shaped cross section are fitted together to form a rectangular parallelepiped.

In the sintered body 12 having an L-shaped cross section, elongated through holes 11a and 11b are formed in the joint surface with the sintered rectangular parallelepiped 13 in a state of being positioned or fitted with the sintered rectangular parallelepiped 13. A base portion 12d formed with elongated grooves 12a and 12b for squeezing and a positioning portion 12e erected vertically from the end of the base portion 12d.

The rectangular parallelepiped sintered body 13 has elongated through-holes 11a and 11b in the joint surface with the L-shaped sintered body 12 in a state of being positioned or fitted with the L-shaped sintered body 12 in cross section. Elongated grooves 13a and 13b for forming are formed.

The elongated grooves 12a and 12b of the L-shaped sintered body 12 and the elongated grooves 13a and 13b of the rectangular parallelepiped sintered body 13 are semicircular in cross section, respectively, and the two sintered bodies are positioned or fitted together. By doing so, elongated through holes 11a and 11b with circular cross sections are formed. Therefore, in FIGS. 3A and 4, the elongated through holes 11a and 11b formed across the bonding surfaces of the two sintered bodies are formed by re-sintering the two sintered bodies together. , elongated through holes 1a and 1b are formed as shown in FIGS. 1 and 3(b).

A plurality of sintered bodies in which the L-shaped sintered body 12 and the rectangular parallelepiped sintered body 13 are fitted to each other have a shape corresponding to the shape obtained by dividing the rectangular parallelepiped molded body 1 as described above. However, in this example, the sintered body 12 having an L-shaped cross section is formed in a shape in which a region including the positioning portion 12e is extended, and the sintered body 12 having an L-shaped cross section and the rectangular parallelepiped sintered body 13 are formed into a shape. After bonding, the re-sintered body is cut at the cutting portion 15 in the cutting step described later, whereby the cuboid molded body 1 can be easily manufactured.

The method of fitting the L-shaped sintered body 12 and the rectangular parallelepiped sintered body 13 is not particularly limited. After placing the body 12 so that the direction of arrangement of the elongated grooves 12a and 12b is perpendicular to the direction of gravity, the elongated grooves 13a and 13a of the rectangular parallelepiped sintered body 13 are placed on the L-shaped sintered body 12 in cross section. It is preferable to mount the rectangular parallelepiped sintered body 13 with the sintered body 13b facing the elongated grooves 12a and 12b. When both sintered bodies are fitted in such an arrangement, the cuboid sintered body 13 is pressed toward the positioning portion 12e of the sintered body 12 having an L-shaped cross section in a direction perpendicular to gravity (long side direction). Both sintered bodies can be brought into close contact, and both grooves for forming the elongated through holes 11a and 11b can be accurately positioned. Moreover, since the corner 12c of the sintered body 12 having an L-shaped cross section is right-angled, it is possible to suppress a slight lifting of the joining surfaces of the elongated through holes 11a and 11b when pressed, and to achieve more precise adhesion.

Further, in the positioning or fitting of the L-shaped sintered body 12 and the rectangular parallelepiped sintered body 13, precise positioning or fitting is required. The shape of the corner 12c is likely to be R-shaped (curved), and it is difficult to form the corner 12c at a precise right angle. Therefore, in this example, the corner 13c of the rectangular parallelepiped sintered body 13 to be fitted with the corner 12c of the sintered body 12 having an L-shaped cross section is chamfered at the tip, and between the corner 12a A gap 14 is formed. Therefore, the rectangular parallelepiped sintered body 13 is placed on the L-shaped cross section sintered body 12, and the rectangular parallelepiped sintered body is sintered toward the positioning part 12e of the L-shaped cross section sintered body 12 in a direction perpendicular to gravity. By pressing the body 13, the rectangular parallelepiped sintered body 13 and the L-shaped cross section sintered body 12 can be brought into close contact. In the cutting step, which will be described later, from the re-sintered body obtained by joining the two sintered bodies, the region that does not include the elongated through holes and includes only the gap 14 may be cut and removed. .

Furthermore, in order to improve the adhesion between the L-shaped sintered body 12 and the rectangular parallelepiped sintered body 13, the parallelism of the joint surface between the L-shaped sintered body 12 and the rectangular parallelepiped sintered body 13 is Each is adjusted to 5 μm or less. Further, the squareness of the corner 12c of the positioning portion 12e of the sintered body 12 having an L-shaped cross section is also adjusted to 5 μm or less.

In the present specification and claims, parallelism and squareness are measured in accordance with JIS B 0022. A dimension measuring instrument is used to measure the squareness of the sintered body.

The step of joining the molded bodies shown in FIG. 1 can be suitably used as a method for manufacturing a molded body having one elongated through-hole or a molded body having a plurality of elongated through-holes arranged in a line.

(Joining process of compact shown in FIG. 2)
A process of joining the compacts shown in FIG. 2, which is another example of the joining process, will be described with reference to FIG.

5A and 5B are schematic end views for explaining the method for manufacturing the compact shown in FIG. Fig. 5(b) is a schematic end view for comparison with the molded body [Fig. 5(b)]. In addition, FIG. 5 is described as a schematic diagram in which the hole diameters of the elongated through-holes are enlarged as compared with FIG. 2 in order to clarify the positional relationship of the elongated through-holes.

The plurality of sintered bodies to be joined in the joining step in FIG. 5, as shown in FIG. A sintered body 22 having an L-shaped cross section, a first sintered rectangular parallelepiped 23, a second sintered rectangular parallelepiped 24 and a third sintered rectangular parallelepiped 25 are fitted together to form a rectangular parallelepiped. ing.

The sintered body 22 having an L-shaped cross section has an elongated through-hole on the joint surface with the first sintered rectangular parallelepiped 23 in a state where it is positioned or fitted with the first sintered rectangular parallelepiped 23 . It is formed of a base portion 22d having elongated grooves 22a and 22b for forming 21a and 21b, and a positioning portion 22e vertically erected from the end of the base portion 22d.

The first rectangular parallelepiped sintered body 23 has an elongated through hole 21a on the joint surface with the L-shaped sintered body 22 in a state of being positioned or fitted with the L-shaped sintered body 22 in cross section. , 21b are formed, and are positioned or fitted with the second rectangular parallelepiped sintered body 24, joining with the second rectangular parallelepiped sintered body 24 Elongated grooves 23c and 23d for forming the elongated through holes 21c and 21d are formed on the surface.

The second rectangular parallelepiped sintered body 24 has an elongated penetrating part on the joint surface with the first rectangular parallelepiped sintered body 23 in a state of being positioned or fitted with the first rectangular parallelepiped sintered body 23 . With the elongated groove portions 24a and 24b for forming the holes 21c and 21d formed, and positioned or fitted with the third rectangular parallelepiped sintered body 25, the third rectangular parallelepiped sintered body 25 and the Elongated grooves 24c and 24d for forming the elongated through holes 21e and 21f are formed in the joint surfaces of the two.

The third rectangular parallelepiped sintered body 25 has an elongated penetrating part on the joint surface with the second rectangular parallelepiped sintered body 24 in a state of being positioned or fitted with the second rectangular parallelepiped sintered body 24 . Elongated grooves 25a and 25b are formed for forming the holes 21e and 21f.

The sintered body 22 having an L-shaped cross section and the elongated grooves of the first to third rectangular parallelepiped sintered bodies 23, 24, and 25 each have a semicircular cross section, and position or fit both sintered bodies. Thereby, elongated through holes 21a, 21b, 21c, 21d, 21e, and 21f having circular cross sections are formed. Therefore, in FIG. 5(a), the elongated through-holes formed across the bonding surfaces of both sintered bodies are re-sintered to bond the two sintered bodies to each other as shown in FIGS. Elongated through holes 2a, 2b, 2c, 2d, 2e, and 2f are formed as shown in (b).

A plurality of sintered bodies having an L-shaped cross section 22, a first rectangular parallelepiped sintered body 23, a second rectangular parallelepiped sintered body 24, and a third rectangular parallelepiped sintered body 25 are fitted together. As described above, the joint has a shape corresponding to the shape obtained by dividing the rectangular parallelepiped molded body 2, but in this example, the region including the positioning portion 22e of the L-shaped sintered body 22 in cross section is extended. After joining the L-shaped sintered body 22 and the rectangular parallelepiped sintered body 23, the re-sintered body is cut at a cutting point 27 in a cutting step described later to obtain a rectangular parallelepiped shape. The compact 2 can be manufactured easily.

The method of fitting the L-shaped cross section sintered body 22 and the first to third rectangular parallelepiped sintered bodies 23, 24, and 25 is not particularly limited, but uniform and straight elongated through holes are easily formed. For this purpose, after placing the elongated grooves 22a and 22b of the sintered body 22 having an L-shaped cross section so that the direction of arrangement of the elongated grooves 22a and 22b is perpendicular to the direction of gravity, a rectangular parallelepiped sintered body is placed on the sintered body 22 having an L-shaped cross section. After the rectangular parallelepiped sintered body 23 is placed with the elongated grooves 23a and 23b of the binding body 23 opposed to the elongated grooves 22a and 22b, the elongated grooves are opposed to each other on the rectangular parallelepiped sintered body 23. It is preferable to place the second sintered rectangular parallelepiped body 24 and the third sintered rectangular parallelepiped body 25 sequentially in the same manner. When both sintered bodies are fitted in such an arrangement, the first to third rectangular parallelepiped sintered bodies are directed toward the positioning portion 22e of the sintered body 22 having an L-shaped cross section in the direction perpendicular to gravity (long side direction). 23, 24 and 25 can be pressed to bring the two sintered bodies into close contact, and each groove for forming the elongated through holes 21a, 21b, 21c, 21d, 21e and 21f can be accurately positioned. Moreover, since the corner 22c of the sintered body 22 having an L-shaped cross section is right-angled, it is possible to prevent slight lifting of the joining surfaces of the elongated through-holes 21a and 21b when pressed, and to achieve more precise adhesion.

For the same reason as the rectangular parallelepiped sintered body 13, the first rectangular parallelepiped sintered body 23 is also the first rectangular parallelepiped to be positioned or fitted to the corner 22c of the positioning part 22e of the L-shaped cross section 22. A corner portion 23e of the sintered body 23 is chamfered at the tip, and a gap 26 is formed between the corner portion 22c and the corner portion 23e. Therefore, the rectangular parallelepiped sintered body 23 is placed on the L-shaped cross section sintered body 22, and directed toward the positioning part 22e of the L-shaped cross section sintered body 22 in the direction perpendicular to the gravity. By pressing the sintered body 23, the first rectangular parallelepiped sintered body 23 and the L-shaped cross section sintered body 22 can be brought into close contact. In the cutting step, which will be described later, from the re-sintered body obtained by joining the two sintered bodies, the region that does not include the elongated through-holes and includes only the gap 26 may be cut and removed. .

Furthermore, in order to improve the adhesion between the sintered body 22 having an L-shaped cross section and the first sintered body 23 having a rectangular parallelepiped, The parallelism of the joint surfaces is adjusted to 3 μm or less. In addition, the parallelism of the joint surfaces of the first to third rectangular parallelepiped sintered bodies 23, 24 and 25 is adjusted to 3 μm or less. Further, the perpendicularity of the corner of the positioning portion 22e of the sintered body 22 having an L-shaped cross section is also adjusted to 3 μm or less.

The step of joining the molded bodies shown in FIG. 2 can be suitably used as a method for manufacturing a molded body having a plurality of elongated through holes that are not arranged in a row.

(Shapes of multiple sintered bodies)
In a plurality of sintered bodies that are fitted together, the elongated through-holes have a shape corresponding to the elongated through-holes of the molded body, preferably substantially the same shape, particularly preferably the same shape.

The shape of the plurality of sintered bodies that are fitted together is a rectangular parallelepiped, and in the present invention, it is important that the corners of the molded body are right angles in order to form uniform and straight elongated through-holes. , the surface shape may be rectangular. Therefore, the surface shape may be rectangular or square. In addition, in order to easily form elongated through holes that are uniform and straight efficiently, when a gap corresponding to the chamfered corner of the rectangular parallelepiped sintered body is formed, the area having the gap is cut and removed. It is preferable that the area where the gap is formed is extended and enlarged in order to facilitate the installation.

In the present invention, the parallelism between the joint surfaces of the L-shaped sintered body and the rectangular parallelepiped sintered body and the joint surfaces between the rectangular parallelepiped sintered bodies may be 10 μm or less. , preferably 8 μm or less, more preferably 5 μm or less, more preferably 3 μm or less, and most preferably 2 μm or less.

Further, the squareness of the corners of the positioning portions of the L-shaped sintered body in cross section may be 10 μm or less, preferably 8 μm or less, more preferably 5 μm or less, more preferably 3 μm or less, and most preferably 2 μm. It is below.

(Conditions for restintering)
The temperature for restintering is, for example, 1200 to 1600°C, preferably 1250 to 1550°C, more preferably 1300 to 1500°C. Resintering may be performed under normal pressure or reduced pressure (or under vacuum), and may be performed under normal pressure or increased pressure. The restintering time is, for example, 1 to 48 hours, preferably 2 to 24 hours, more preferably 3 to 20 hours.

The elongated through-holes of the re-sintered body obtained by re-sintering the sintered body in the bonding step have the average pore size, aspect ratio, pore size distribution and parallelism described in the shape of the compact. Since the elongated through-holes are uniform and straight, they can be used as they are as the molded article of the present invention.

[Grinding process]
In the method for manufacturing a molded body of the present invention, as a pre-process of the joining step, a grinding step of grinding and forming, with a grinder, elongated grooves for forming elongated through-holes in the plurality of sintered bodies. It may contain further.

The grinder is not particularly limited as long as it can precisely form the concave portion corresponding to the desired elongated through hole, and a commonly used grinder can be used. Examples of conventional grinders include optical profiling grinders (optical profiling grinders or profile grinders), mechanical profiling grinders, optical-mechanical profiling grinders, universal tool grinders, NC grinders, jigs Grinding machines, thread grinding machines, worm grinding machines, crankshaft grinding machines, cam grinding machines, spline grinding machines, roll grinding machines, bearing groove grinding machines, bench grinding machines, etc. can be used.

Among these grinders, an optical profile grinder and a jig grinder are preferable, and an optical profile grinder is particularly preferable, because they can easily form elongated through-holes that are uniform and straight.

As a grinding method, a conventional method using a grinding machine can be used.

[Electrical discharge machining process]
The method for producing a compact of the present invention further includes an electrical discharge machining step (hole electrical discharge machining or WE electrical discharge machining step) of inserting elongated electrodes into the elongated through-holes of the re-sintered body for electrical discharge machining. good too.

The re-sintered body obtained in the joining process has uniform and straight elongated through-holes formed by joining multiple sintered bodies. If through-holes are required, the elongated through-holes of the resintered body may be further subjected to pore electrical discharge machining or WE electrical discharge machining.

In electrical discharge machining or WE electrical discharge machining for an elongated through-hole, as shown in FIG. 6, an elongated through-hole 31a formed in a sintered body 31 with a diameter of φa is provided with an elongated electrode 32 with a diameter of φb. It is inserted and EDM machined. Specifically, the elongated electrode 32 is inserted into the inner wall of the elongated through-hole 31a with a gap (discharge margin) without contact, thereby causing an arc discharge and finishing the inner wall of the elongated through-hole 31a. By processing, the shape of the elongated electrodes 32 can be transferred, but in order to accurately transfer the shape of the elongated electrodes 32, it is desirable to reduce the discharge margin. On the other hand, in order to form a small gap in the elongated through-holes 31a as in the present invention, it is necessary to form highly uniform and straight elongated through-holes. For example, when the hole diameter φa of the elongated through hole 31a is about 70 μm, the diameter φb of the elongated electrode 32 is about 50 μm, resulting in a fine gap with a discharge allowance of about 10 μm. On the other hand, in the present invention, uniform and straight elongated through-holes are formed in the compact, so die-sinking electric discharge machining becomes possible, and precise elongated through-holes can be formed. On the other hand, in the conventional elongated through-holes such as those disclosed in Patent Document 1, uniform and straight elongated through-holes cannot be formed. The electrodes are in contact and die-sinking electrical discharge machining cannot be performed.

The shape of the elongated electrode may correspond to the elongated through hole. The diameter of the elongated electrodes is, for example, 5-110 μm, preferably 10-100 μm, more preferably 20-90 μm, more preferably 30-80 μm, most preferably 50-70 μm.

In electrical discharge machining, the gap (discharge margin) between the elongated electrode and the elongated through hole is, for example, 1 to 30 μm, preferably 3 to 20 μm, more preferably 5 to 15 μm.

[Cutting process]
In the method for producing a molded body of the present invention, the re-sintered body obtained in the bonding step does not include elongated through holes and corners of the rectangular parallelepiped sintered body or the first rectangular parallelepiped sintered body are removed. From the resintered body obtained in the first cutting step of cutting and removing the region including the gap formed by chamfering the part or the electric discharge machining step, the rectangular parallelepiped not including the elongated through hole and It may further include a second cutting step of cutting and removing a region including a gap formed by chamfering corners of the shaped sintered body or the first rectangular parallelepiped shaped sintered body.

When the method for producing a molded body of the present invention includes an electric discharge machining step, the cutting step may be performed on the resintered body obtained in the joining step, or may be performed on the resintered body obtained in the electric discharge machining step. may

In the manufacturing method of the molded article of the present invention, the cutting step is not an essential step, and is unnecessary when the gap is not formed. In the case where the gap does not interfere with the application, it may be used as a molded body having the gap.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited by these examples.

Example 1
[Grinding process]
Using a profile grinder (“SPG-WiL” manufactured by Waida Seisakusho Co., Ltd.) equipped with a diamond grindstone (φ 150 mm, # 400), a semicircular shape with an R of 0.040 mm at a rotation speed of 4000 rpm and a rocking speed of 60 st / min. A rectangular parallelepiped sintered body having an elongated groove and a sintered body having an L-shaped cross section were molded. The projection magnification of the profile grinder was 50 times.

[Joining process]
As shown in FIG. 5(a), the rectangular parallelepiped sintered body is placed on the sintered body having an L-shaped cross section, and is directed toward the positioning portion of the sintered body having an L-shaped cross section in a direction perpendicular to gravity. 1 to 3 rectangular parallelepiped sintered bodies were sequentially pressed and sintered at 1400° C. for 7 hours under vacuum to obtain a resintered body. Photographs of the resulting resintered body obtained by equally dividing the elongated through-holes along the length direction, and the upper ends (A) of the elongated through-holes in the cut resintered body. , respectively enlarged photographs of the central part (B) and the lower end part (C) are shown in FIG. As is clear from FIG. 7, the obtained re-sintered body has uniform and linear elongated through-holes formed in all regions of the upper end (A), the central portion (B), and the lower end (C). It had been. Furthermore, when the size of the elongated through-holes was measured, the average pore diameter was 73 μm, the aspect ratio, which is the ratio of the length to the pore diameter, was 273 times, the dispersion of the pore diameters was 3%, and the parallelism was 2 μm.

[Electrical discharge machining process]
Using an elongated electrode (“AP450L” manufactured by Sodick Co., Ltd.), the elongated through-hole was processed to have a diameter of φ0.1 mm with a WE wire diameter of φ0.05 mm.

[Cutting process]
As shown in FIG. 5(a), a WE processing machine was used to cut the re-sintered body to obtain a molded body.

The molded article of the present invention can be used as a molded article that requires elongated through-holes, and in particular, molds for precision machinery and electronic parts that require fine and uniform straight filaments (for example, inkjet printers). molds for forming nozzles, etc.).

DESCRIPTION OF SYMBOLS 1... Molded object 1a, 1b... Porous through-hole

Claims (14)

A method for producing a molded body made of cemented carbide and having at least one elongated through hole, comprising:
a joining step of aligning at least one elongated groove formed on the joint surface and sintering and joining a plurality of sintered bodies to obtain a cuboid resintered body having at least one elongated through hole ;
an electric discharge machining step of inserting a porous electrode into the elongated through-hole of the re-sintered body and performing electric discharge machining ;
The average hole diameter of the elongated through-holes of the molded body is 200 μm or less, and the length of the elongated through-holes is 30 times or more the average hole diameter, and
The production method, wherein the plurality of sintered bodies are divided in the longitudinal direction across the elongated through-holes of the re-sintered rectangular parallelepiped body. In the bonding step,
The rectangular parallelepiped resintered body is a resintered body in which a cross section L-shaped sintered body and a rectangular parallelepiped sintered body are positioned and sintered together,
a base portion in which an elongated groove for forming an elongated through hole is formed in a bonding surface in a state in which the sintered body having an L-shaped cross section is positioned with the sintered body having a rectangular parallelepiped; and the base portion. and a positioning portion erected from the end of the
The rectangular parallelepiped sintered body is formed with an elongated groove portion for forming an elongated through hole in the joint surface in a state of being positioned with the L-shaped cross section sintered body, and the L-shaped cross section sintered body 2. The manufacturing method according to claim 1, wherein the corners of the rectangular parallelepiped sintered body positioned at the corners of the positioning portion of the body are chamfered to provide a gap between the corners. The parallelism of the contact surfaces of the sintered body having an L-shaped cross section and the sintered body having a rectangular parallelepiped is 3 μm or less, and the squareness of the corners of the sintered body having an L-shaped cross section is 3 μm or less. Item 2. The manufacturing method according to item 2. In the bonding step,
The resintered rectangular parallelepiped body is a restintered body obtained by positioning and sintering a sintered body having an L-shaped cross section , a first sintered rectangular parallelepiped body, and at least one other sintered rectangular parallelepiped body. is the body,
a base portion having an elongated groove for forming an elongated through-hole in the bonding surface in a state in which the sintered body having an L-shaped cross section is positioned with the first rectangular parallelepiped sintered body; and a positioning part erected from the end of the base part, and in a state where the sintered body having the L-shaped cross section is positioned on the first rectangular parallelepiped sintered body, an elongated shape is formed on the bonding surface. An elongated groove for forming a through-hole is formed, and an elongated groove for forming an elongated through-hole is formed in the bonding surface in a state of being positioned with the other rectangular parallelepiped sintered body,
An elongated groove portion for forming an elongated through hole is formed in the joint surface in a state in which the rectangular parallelepiped sintered bodies are positioned in the other rectangular parallelepiped sintered body, and the L-shaped cross section is sintered. 2. The manufacturing method according to claim 1, wherein the corners of the first rectangular parallelepiped sintered body positioned at the corners of the positioning portion of the body are chamfered to provide a gap between the corners. Parallelism of joint surfaces between the sintered body having an L-shaped cross section and the first sintered rectangular parallelepiped body is 3 μm or less, and the first sintered rectangular parallelepiped body and the other sintered rectangular parallelepiped body have a parallelism of 3 μm or less. The parallelism of the joint surfaces of the other rectangular parallelepiped sintered bodies is 3 μm or less, and the parallelism of the joint surfaces of the other rectangular parallelepiped sintered bodies is 3 μm or less, and the corners of the L-shaped sintered bodies in cross section are straight. 5. The manufacturing method according to claim 4, wherein the angle is 3 [mu]m or less. 6. The method of claims 1 to 5, comprising a grinding step of forming elongated grooves for forming elongated through-holes in the plurality of sintered bodies by grinding with an optical copying grinder as a pre-process of the bonding step. The manufacturing method according to any one of the items. From the resintered body obtained in the joining step, a gap which does not include an elongated through hole and is formed by chamfering the corners of the rectangular parallelepiped sintered body or the first rectangular parallelepiped sintered body is removed. 6. The manufacturing method according to claim 4 or 5, further comprising a cutting step of cutting and removing the containing region. A gap formed by chamfering corners of the rectangular parallelepiped sintered body or the first rectangular parallelepiped sintered body, which does not include elongated through-holes, from the resintered body obtained in the electrical discharge machining step. 6. The manufacturing method according to claim 4 or 5, comprising a cutting step of cutting and removing the region containing A cuboid molded body made of cemented carbide and having at least one elongated through hole,
The elongated through-holes have an average pore diameter of 200 μm or less,
A rectangular parallelepiped molded body having a pore diameter dispersion of 20% or less with respect to the average pore diameter in the length direction of the elongated through-holes, and a length of the elongated through-holes 30 times or more the average pore diameter. . 10. The rectangular parallelepiped molded article according to claim 9 , wherein the elongated through holes have a parallelism of 30 [mu]m or less. 11. The cuboid molded article according to claim 9 or 10 , wherein the opening shape of said elongated through holes is circular, elliptical or polygonal. 11. The cuboid molded article according to claim 9 or 10 , wherein the elongated through holes have circular openings. 11. The cuboid molded article according to claim 9 or 10 , having a plurality of elongated through-holes extending in parallel at intervals. 11. The cuboid molded article according to claim 9 or 10 , which is a mold.

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