JPH0866214A - Production of noble metal hollow product - Google Patents

Abstract

PURPOSE: To seal butt parts by brazing filler metals and to improve the quality of hollow shape products by inserting these brazing filler metals into hollow base materials and heating the materials in this state to a temp. above the m. p., of the brazing filler metals and below the m. p. of the base materials, thereby evaporating the brazing filler metals. CONSTITUTION: The brazing filler metals 22 of the semispherical products 211 , 212 are charged into the semispherical products. Only the brazing filler metals 22 are first put into a molten state and are evaporated when the semispherical products 211 , 212 are heated to the temp. above the m. p. of the brazing filler metals 22 and below the m. p. of these products in the state of butting the semispherical apertures against each other. The elements of the lowered m. p. of the brazing filler metals 22 are diffused and intruded into the semispherical products 211 , 212 near the joint boundaries to lower their m. p. by holding the temp. of the joint parts. The semispherical products 211 , 212 near the joint boundaries, therefore, begin to melt together with the brazing filler metals 22. The concn. of the m. p. lowering elements near the joint boundaries lowers and the m. p. begins to rise when the diffusion progresses further in the joint parts in a molten state. The molten parts near the joint boundaries, therefore, begin to solidify again and are finally uniformly joined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hollow product of a precious metal which can be suitably used as an accessory, for example, and provides a method for producing a hollow product of a precious metal which enables mass production.

[0002]

2. Description of the Related Art As a conventional method for producing a hollow product made of a noble metal which is applied to an accessory or the like, half hollow products are butted together, and the butted parts are joined by bonding, and then joined. The part was polished.

However, in the above-mentioned conventional example, there is a defect that the hollow product is distorted at the time of joining, or the appearance is impaired due to discoloration of the bonding portion or discoloration due to aging. Moreover, there is a drawback that defective products are likely to occur in addition to poor mass productivity, and therefore improvement thereof has been demanded.

In recent years, Japanese Patent Laid-Open No. 4-33553 proposes a method which does not use a roller at all. In this method, when a hollow product is manufactured, a hemispherical product is manufactured and the open portions thereof are butted. In this state, it is heated under a non-oxidizing atmosphere gas at a temperature below the solidus. The hollow-shaped product obtained by such a method is excellent in quality, but it is very difficult to control the manufacturing conditions for heating at a temperature below the solidus, and it is difficult to improve mass productivity. There are drawbacks.

[0005]

DISCLOSURE OF THE INVENTION The present invention does not cause discoloration of a hollow product after joining, does not cause discoloration of a portion to be attached or discoloration due to aging, and manages manufacturing conditions easily. It is intended to provide a method for producing a noble metal hollow product suitable for mass production.

[0006]

That is, according to the present invention, when a hollow-shaped product is manufactured from a noble metal, a base material obtained by dividing the hollow product into halves is produced, and a raw material is placed in the halved base material. After putting in, put the half-opened part of the base material into a butted state,
This is placed in an atmosphere of non-oxidizing atmosphere gas and heated at a temperature not lower than the melting point of the base material and lower than the melting point of the base material to vaporize the base material and seal the abutted portion with the base material. The present invention relates to a method for producing a hollow noble metal product characterized by the following. When the half-opened portions of the base material are butted, they can be accommodated in a jig in a butted state.

[0007]

The method for producing a hollow product of a noble metal of the present invention is the above-mentioned method, and a noble metal product having a hollow shape can be efficiently produced at low cost, and the obtained hollow product has a very high quality. It will be excellent.

That is, when the raw material is heated at a temperature above the melting point of the raw material and below the melting point of the base material in a state where the raw material is enclosed in a hollow base material, the raw material is melted and vaporized, Low
The melting point lowering element in the material penetrates and diffuses from the abutting portion of the base material to lower the melting point. Therefore, the base material in the vicinity of the butted surfaces also begins to melt. As the diffusion progresses further,
The concentration of the melting point depressing element near the bonding interface decreases, and the melting point begins to rise. Therefore, the once melted portion near the bonding interface starts solidifying again. In this way, with the passage of time, the entire butted portion is integrated, and the composition becomes almost homogeneous, and a complete hollow body is formed.

That is, in the diffusion welding of the present invention, compared with welding at a temperature below the solidus without using a rod material, the abutting portion (bonding boundary surface) is in a molten state, so that the welding pressure is very low. Therefore, the manufacturing conditions and the like can be controlled very easily. Further, since the manufacturing apparatus can be a continuous manufacturing line, it is possible to provide a manufacturing method of a precious metal hollow product which is more producible in mass production.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for producing a hollow product of a noble metal according to the present invention will be described below with reference to the drawings by taking an example of producing a hollow round ball. 1 and 2 show a jig capable of accommodating a base material made of a hemispherical product obtained by dividing a hollow ball into halves. As shown in FIG. 1, this jig is used for hemispherical products 21 ₁ , 2
A jig body 1 _{1 made of} a heat-resistant material having a plurality of recessed holes 2 ₁ for accommodating 1 ₂ and a hemispherical product 2 facing the recessed holes 2 _1.
1 ₂ jig cover 1 ₂ recessed hole 2 ₂ is formed to be accommodated
The hemispherical products 21 ₁ and 21 ₂ are filled with the roll material 22 and housed in a state where the openings are butted.

As the rod 22, various rod-shaped, sheet-shaped, paste-shaped, and powder-shaped rods can be used, but the rod-shaped rod is most suitable.

[0012] The jig body 1 _1, in a state the jig cover 1 ₂ holding the hemispherical product 21 _1, 21 _2, was placed in a vacuum device 3, the outside air hemispherical product 21 _1, 21 ₂ surrounding space It is desirable to shut it off from Now, the hollow product hemispherical product 2
1 _1, 21 ₂ the jig body 1 ₁ is fitted to, the jig cover 1 ₂ is evacuated housed in a vacuum apparatus 3. After reaching a predetermined vacuum pressure, a non-oxidizing atmosphere gas is supplied and filled. As the non-oxidizing atmosphere gas, an inert gas or a reducing gas can be used, and hydrogen gas, nitrogen gas, argon gas and the like are particularly suitable. Of course, depending on the temperature conditions and the like, the gas can be sent to the subsequent heating step without the gas replacement, and the liquid phase diffusion welding can be sufficiently endured.

[0013] Thus jig 1 ₁ is filled inside with a non-oxidizing atmosphere gas to and the jig cover 1 ₂ includes a vacuum device 3
The liquid phase diffusion welding is carried out by taking out the sheet from the container and putting it in the endless belt type atmosphere furnace 4 shown in FIG.

The endless belt type atmosphere furnace 4 conveys the jig body 1 ₁ and the jig 5 cover _{12 and} a conveying path 5 and the conveying path 5 to convey the jig body 1 _{1 and the} like. An endless belt conveyor 6 and a plurality of heats installed on the upper part of the transport path 5.
And a gas introduction system 8 for supplying a non-oxidizing atmosphere gas to the transport path 5. The temperature of each heater 7 can be controlled for each zone from N1 to Nn.
Each of the heaters 7 has a preheating zone N1 to Nn 'and a uniform heating zone.
It is desirable to accurately control the temperature by dividing it into Nn ′ + 1 to Nn. Hemispherical product 21 _1, 21 ₂ in the non-oxidizing atmosphere gas of the jig main body 1 ₁ is Hitoshinetsuzo - down Nn '+ 1
˜Nn, the liquid is above the liquidus, and is heated under the temperature conditions at which joining is possible. That is, the hemispherical product 21 at the melting point of the raw material 22 or more
_The heating is performed at a temperature below the melting point of ₁ , 21 ₂ .

As described above, the semi-spherical products 21 ₁ and 21 ₂ are put into the semi-spherical product 22 and the semi-spherical product 22 is put into the semi-spherical product. _When heated at a temperature equal to or lower than the melting point of ₁ , 21 ₂ , only the raw material 22 is initially in a molten state and vaporized. that time,
By maintaining the temperature of the joining portion, the element whose melting point of the rod material 22 is lowered is a hemispherical product 21 ₁ , 21 near the joining boundary.
₂ Diffuses and penetrates into ₂ to lower melting point. Therefore, the hemispherical products 21 ₁ and 21 ₂ near the bonding interface together with the base material 22 also start to melt. Then, when the diffusion action further progresses in the bonded portion in the molten state, the concentration of the melting point depressing element near the bonding interface decreases, and the melting point begins to rise. Therefore, the melted portion near the bonding interface begins to solidify again. And
When the solidification of the entire bonded portion is completed with the lapse of time and the diffusion further proceeds, the composition of the bonded portion becomes substantially uniform, and good bonding can be obtained.

In the present invention, the above diffusion bonding can be easily and inexpensively carried out under the internal atmospheric pressure of the jig body 1 and the pressure condition that the upper hemispherical product 21 'is not weighted or the product is not deformed. The liquidus line refers to a melting temperature above the solidus line, which is a standard for an alloy to change from a fixed state to a liquid state, and varies depending on the composition of the alloy. Therefore,
It is necessary to adjust the temperature conditions according to the composition of the noble metal that constitutes the hollow product.

To further explain the melting action in the diffusion welding, the roll material 22 having a lower melting point, for example, about 800 ° C. is put into a hemispherical product having a melting temperature for example, about 870 ° C. To do. When the hemispherical products 21 ₁ and 21 ₂ and the roll material 22 are heated in this state, the noble metals forming the hemisphere products 21 ₁ and 21 ₂ are vaporized and become compatible with each other. The action occurs, and the melting temperature of the portion is lowered to the range of about 830 to 850 ° C. Therefore, if they are heated at a temperature above the liquidus in this range, they will be welded securely, and the rod material 22 will become a hemispherical product.
It melts into the noble metal forming 1 ₁ and 21 ₂ , and a good welded state can be obtained in which there are no visible defects.

In the liquid phase diffusion welding, compared with the solid phase diffusion welding at a temperature below the solidus line without using a rod material, the welding pressure is very low because the vicinity of the welding interface is in a molten state. The feature is that it is possible to manage manufacturing conditions and the like extremely easily.

The hollow noble metal product of the present invention obtained as described above was of excellent quality without being oxidized and discolored, and free from deformation and pinholes.

Next, the noble metal hollow products of the present invention can be used for various accessories such as earrings, pendants, rings, and broaches, which greatly contributes to the weight reduction and cost reduction of the products. Is.

Unlike the above-mentioned embodiment, the noble metal hollow product can be manufactured in a batch process. That is, a hemispherical product, which is a hollow product, is housed together with a jig main body in a vacuum device having a heating mechanism, and the above-mentioned hermetically sealable jig main body and jig cover are abutted with their openings in a non-oxidizing atmosphere gas atmosphere. Then, by heating in a vacuum furnace under a non-oxidizing atmosphere gas, a hollow product joined by liquid phase diffusion welding can be obtained as in the above embodiment.

[0022]

EFFECTS OF THE INVENTION Since the method for producing a hollow noble metal product of the present invention is configured as described above, it is possible to efficiently produce a hollow precious metal product at a low cost without using a large-scale production apparatus. The present invention provides a method for producing a precious metal hollow product, in which the hollow product has excellent quality. In addition, since the manufacturing apparatus can be a continuous manufacturing line, it is possible to provide a method for manufacturing a noble metal hollow product that is even more productive.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a jig body 1 used in the method for producing a hollow noble metal product of the present invention.

FIG. 2 is a schematic diagram of an atmospheric furnace.

[Explanation of symbols]

1 ₁ ... jig main body, 1 ₂ ... jig cover, 2 ₁ , 2 ₂ ... concave hole, 3 ... vacuum device, 4 ... atmosphere furnace, 5 ... transport path, 6 ... belt conveyor , 7 ‥‥ heat - data, 8 ‥‥ gas introduction system, 21 _1, 21 ₂ ‥‥ hemispheres product, 22 ‥‥ Russia - wood.

Claims (1)

[Claims] 1. When manufacturing a hollow product made of a noble metal, a base material obtained by dividing the hollow product into halves is prepared, and a raw material is put into the halved base material. The split opening is placed in a butt state, placed in an atmosphere of a non-oxidizing atmosphere gas, and heated at a temperature not lower than the melting point of the base material and lower than the melting point of the base material to vaporize the base material to form the butt portion. A method for producing a hollow noble metal product, which comprises sealing with a raw material.