JPS6212431B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal tube that penetrates the center of a metal tube and is used, for example, to penetrate the wall of a metal airtight container or to maintain electrical insulation by interposing it in the middle tube of a metal tube. Regarding the manufacturing method of insulated pipe fittings with holes, that is, electrically insulated pipe fittings, for example, in cooling devices that use low-temperature liquids such as liquid nitrogen or liquid helium, or liquids or gases that are higher than room temperature at 100°C to 200°C. The present invention relates to a method of manufacturing an insulating pipe joint that is suitably used for maintaining insulation and distributing pipes. Note that in this invention, insulation means electrical insulation. The main characteristics required of insulated pipe joints used for the above purpose are as follows.

It has good airtightness, has excellent resistance to cold and thermal shocks and does not deteriorate due to repeated rapid rises and falls in temperature, has high mechanical impact strength, and has long-term reliability with no changes over time. It is. In addition, in order for it to be widely put into practical use, it must be easy to attach to the vessel wall or connect to a metal pipe, have a small outer diameter for a certain flow rate, be easy to manufacture, and be inexpensive. There is an urgent need for this to be the case.

In the case of this type of insulated pipe joint, the basic structure is a structure in which an insulator is interposed between two conduits. In this case, it is the insulator that has the greatest control over the characteristics.
This insulator will be explained below. When organic materials are used as insulators, the temperature may rise or
Alternatively, if the material is repeatedly raised and lowered, its airtightness deteriorates due to changes in the properties of the material itself over time, which is a fatal flaw, making it unusable in reality. Next, when glass material is used, there are defects such as cracks occurring due to sudden changes in temperature or low mechanical impact strength. As in the case of , they have a fatal flaw of low thermal and mechanical impact strength, and these also cannot be used in reality. An insulator made of a glass-mica plastic body, which will be described in detail below, is the most excellent in terms of all the above-mentioned characteristics.

A glass mica plastic body is obtained by using a mixture of glassy powder and mica powder as raw material, heating this raw material powder to a temperature at which the glassy substance softens and flows under pressure, and then press-molding it in the heated state. It refers to an insulator.

The most ideal insulated pipe joint using a glass mica plastic body as an insulator is the one previously proposed by the authors (see Japanese Patent Application No. 55-51151 and Japanese Patent Publication No. 34037-1982). The structure will be explained below with reference to FIG.

FIG. 1 is a longitudinal cross-sectional view showing the structure. In FIG. 1, 1 is a cylindrical first tubular member, 2 is a cylindrical second tubular member, and a shoulder 2-1 is connected to one end of the member.
The first tubular member 1 is provided with an outer peripheral fitting 2-2 having an inner diameter larger than the outer diameter. All of them are made of metal that can withstand heating of about 600°C, and iron, stainless steel, etc. are preferably used. The first and second tubular members 1 and 2 are supported by holding spaces 3 and 3-1, and the spaces 3 and 3-1 are filled with an insulator 4 made of glass mica plastic, The first tubular member 1 and the second tubular member 2 are completely sealed and fixed, and insulation is maintained. 1a and 2a are connected to the vessel wall or metal pipe by an appropriate method such as welding or screwing. This insulated pipe joint completely maintains the required basic properties such as airtightness, thermal and mechanical impact strength, and reliability against aging. If the inner diameter is smaller than 1 inch (25.4 cm), manufacturing is relatively easy, but if the inner diameter is large, e.g. 3 inches (7.62 cm) or 10 inches (25.4 cm), molding equipment may be required. Its manufacture becomes extremely difficult. Even if equipment meeting the necessary conditions were installed, the manufacturing process would be complicated and the manufacturing price would be extremely high. There is a very serious flaw.

The present invention provides a method for easily manufacturing even large-sized products. Prior to explaining the contents, a conventional manufacturing method for small shaped products will be explained with reference to FIG.

Figure 2 is a vertical cross-sectional view showing the state of conventional molding for small shaped products. Figure 2a (left half) shows the state immediately before pressure molding, and Figure 2b (right half) shows the state immediately before pressure molding. This shows the state after pressure forming is completed. 1, 2, 2-1, 2-2, 3, 3-1 and 4 in Figure 2
is the same part as in Figure 1. Reference numeral 1-2 is a support section provided at the bottom of the first tubular member. Reference numeral 5 denotes a wall portion of the divided structure, 6 a frame, and 7 a holding stand which is located in the central through hole of the second tubular member and supports the support portion 1-2 of the first tubular member 1. The space 3-1 between the second tubular member 2 and the first tubular member 1 is
It has a structure that maintains its conical shape. Reference numeral 8 denotes a support stand, which is located between the wall portion 5 and the second tubular member 2;
The shoulder portion 2-1 of the tubular member 2 is supported. Reference numeral 9 denotes a pressurized metal, which is made to fit into the wall portion 5 and the first tubular member 1. Reference numeral 10 denotes a presser metal, which is located above the first tubular member 1 and functions to pressurize the first tubular member 1 by receiving the pressing force of the drive unit 11.

A mold made up of the above five parts is used. 1
2 is a preformed product, which is made into a cylindrical product with a through hole in the center by adding moisture to a mixed powder of glassy powder and mica powder, which is the raw material of the insulator 4, to make it moist, and using another mold (not shown) in advance. It is molded and dried to remove moisture.

For molding, as shown in FIG. 2a, the wall portion 5, frame 6, holding table 7, and support table 8 are assembled and heated to a predetermined temperature together with the unassembled pressurizing metal 9. Oshigane 1
0 means no heating. The first tubular member 1, the second tubular member 2, and the preform 12 are each heated to a predetermined temperature. When heating is completed, first, the second tubular member 2 is inserted into the space between the holding table 7 and the supporting table 8. Next, the first tubular member 1 is placed on the support base 7. Next, the pusher 10 is placed on the first tubular member 1, and finally the preform 12 is placed on the second tubular member 2.
Place it on top. The state at this time is shown in FIG. 2a. When the insertion is completed, the presser metal 9 is placed on the preform 12, and the drive unit 11 moves the presser metal 10
Pressure is then applied to the press metal 9 using a pressure molding machine. The preform 12 flows and fills the spaces 3 and 3-1 and forms the insulating part 4. The state at this time is shown in FIG. 2b.
When the preform 12 flows, the first tubular member 1
A floating pressure shown by an arrow 13 is generated on the bottom surface of the tube, and a phenomenon occurs in which the first tubular member 1 floats. In order to prevent this floating, the presser metal 1 is
It is necessary to apply a pressure greater than the levitation pressure to 0 to prevent levitation. When the pressure molding process is completed, the molded product is cooled to a predetermined temperature, the mold is separated, and the molded product is taken out. The molded product is obtained by removing the deleted portion 14 indicated by the vertical chain line in FIG. 2b by machining.
Make the product shown in Figure 1.

The conventional method described above can be applied extremely effectively when the inner diameter of the tubular members 1 and 2 is thinner than about 1 inch as described above, but it becomes difficult to apply when the inner diameter becomes thicker. . The reason for this will be explained below.

Generally, when molding a glass mica plastic body, a pressing force of 1 to 2 ton/cm ² is required during molding. Specifically, in FIG. 2, when the total pressure on the preform 12 is set to 400 tons, the buoyancy force indicated by arrow 13 reaches 200 to 250 tons. In order to satisfy the above conditions, the pressure molding machine is equipped with a main drive part (not shown) with a capacity of 400 tons for pressurizing the pressure metal 9, and a main drive part inside this main drive part. Independently from this section, a sub-drive section 11 for pressurizing the pusher 10 is required to have a capacity of 250 tons. When an independent sub-drive section is provided inside the main drive section as described above, the capacity of the sub-drive section is 30% of the capacity of the main drive section.
is the general limit. Therefore, if the capacity of the sub-drive section is set to 250 tons, the capacity of the main drive section will inevitably be approximately 800 tons. As the pressure molding machine used as the forming equipment becomes huge, the product price inevitably rises, and the equipment becomes larger.
Many problems occur in manufacturing, such as making molding operations difficult and making stable molding difficult, and as a practical matter, there is a fatal flaw in that production becomes impossible.

The present inventors have developed a special and large-capacity pressure-molded product that completely retains the excellent characteristics of a small-sized insulated pipe joint using a glass mica plastic body as an insulator and sealant. After conducting as much research as possible to obtain an insulated pipe joint that could be manufactured at low cost without using a machine, we succeeded in obtaining a satisfactory product.

Next, an embodiment of the method for manufacturing an insulated pipe joint according to the present invention will be described with reference to FIGS. 3 and 4. Third
FIG. 3a is a longitudinal sectional view showing a state in which molding has been completed, and FIG. 3b is a longitudinal sectional view showing the structure of the product after machining. Prior to the detailed description, the manufacturing method will be explained with reference to FIG. The mold for molding is 5,
Uses one consisting of 4 parts 6, 8, and 9,
This is the same as shown in FIG. As the second tubular member 2, a member similar to the conventional product shown in FIG. 2 is used. The first tubular member 1 is a straight tube-shaped product whose lower end surface 1-3 is in contact with the shoulder portion 2-1 of the second tubular member 2. Similar to the conventional forming method described in FIG. 2a, the mold, the first and second tubular members 1, 2, and the preform 12 are heated to a predetermined temperature, as shown in FIG. 4a. The preformed body 12 is then pressurized by the pressurizing metal 9. The state after pressure forming is shown in FIG. 4b. At this time, the preformed body 12 becomes an insulator 4 made of a glass mica plastic body and is filled into the space 3. In this case, unlike the conventional manufacturing method shown in FIG. 2, the insulator 4 is not interposed on the lower end surface of the first tubular member 1, so no floating pressure is generated in the first tubular member 1. Therefore, it is not necessary to apply pressure to the first tubular member 1 to prevent floating before pressurizing the preformed body 12. Once forming is completed, the lower end 1-3 of the first tubular member 1 is machined. The product is then cut and removed to produce a product as shown in Figure 3b. As is clear from the above explanation, according to the manufacturing method of the present invention, it is not necessary to pressurize the first tubular member 1, so the function of the pressure molding machine as molding equipment is extremely simplified, and it is generally Preformed body 1 using a pressure molding machine
Any machine with a pressurizing capacity for the total pressurizing force of 2 can be used, large-sized products can be manufactured easily, and the problems associated with pressure molding machines have been completely solved.

Although the gist of the present invention is clear from the above description, in order to facilitate understanding, the relationship between the pressure molding pressure and the floating pressure of the first tubular member 1 will be specifically explained together with the molding conditions.

First, the preform 12 is created, and the vitreous materials include PbO: 0.7, ZnO: 0.3, B ₂ O ₃ : 0.5, and SiO ₂ :
Glassy powder 48W% made by crushing a product with a molar ratio of 0.5 into 200 meshes, synthetic fluorine-containing gold mica powder 60~
The raw material is a mixture of 52W% 150 mesh product and 5W% water added to make it wet. Using another mold (not shown), cold pressure molding is performed according to the size and shape of the molded product. The required amount was molded into a cylindrical shape that could be filled and kept in a dryer at 120°C to remove moisture.

Next, iron material was used for the tubular members. Next, regarding the molding conditions, pressure molding is performed by heating the mold to 450°C, heating the first tubular member 1 and second tubular member 2 to 550°C, and heating the preform 12 to 650°C. Ivy.

The relationship between the pressure force during pressure molding and the levitation force of the first tubular member will be specifically explained with reference to the structural shape of the insulated pipe joint. First of all, although it is a small-sized product, the inner diameter of the first tubular member 1 and the second tubular member 2 is 25 mmφ, the outer diameter is 35 mmφ, and the inner diameter of the outer peripheral fitting 2-2.
41mmφ, outer diameter 51mmφ, inner diameter of support part 1-2 15mmφ
The diameter of the upper end of the support base 7, which was molded by the method shown in FIG. 2 using a tubular member, was 19 mmφ. The pressure applied to the preform 12 by the pressurizer 9 was 1.5 ton/
The total pressure in cm ² is 16.2 tons. At this time, the area receiving the levitation pressure is (35 ² −19 ² )×π/4=6.78cm ² and the total levitation pressure is 10.16 tons. However, this calculated value ignores the internal resistance of the fluid in the preform 12, and in reality it is reduced by about 20% to about 8 tons. As mentioned above, the capacity limit of the auxiliary drive section is generally about 30% of the main drive section capacity, so the main drive section
It can be easily manufactured by using a pressure molding machine with a capacity of 50 tons and a sub-drive section of 10 tons.

Next, regarding large-sized products, the first tubular member 1 and the second tubular member 2 have an inner diameter of 250 mm and an outer diameter of 300 mm.
The inner diameter of the outer peripheral fitting 2-2 is 312 mm, the outer diameter is 362 mm,
If a tubular member with an inner diameter of 226 mm is used for the support part 1-2 and molded by the method shown in FIG. 2, the diameter of the upper end of the support will be 234 mm. In this case, if the pressurizing force of the preform 12 is set to 1.5 ton/cm ² , the pressurized area will be 321.8 cm ² , so the total pressure will be 482 tons. In this case, the area subject to flotation will be (300 ² −234 ² ) ×π/
4 is 276.6 cm ² and the total levitation force is 415 tons, and if the reduction rate due to internal resistance is 20%, it becomes 331 tons. If the capacity of the auxiliary drive section is 331 tons, which is 30% of the main drive section, a main drive section with a capacity of about 1100 tons will be required, and as a practical matter, it will be difficult to manufacture without a pressure molding machine with the above performance. It becomes impossible. If the structure shown in FIG. 4 is changed and a tubular member of the above dimensions is molded, floating pressure will not be generated, so molding is possible if the main drive section is equipped with a pressure molding machine with a capacity of 428 tons.

According to the manufacturing method of the present invention, even if the manufactured insulated pipe joint becomes large in size, it has the same airtightness, cold thermal and mechanical impact strength as the small-shaped product manufactured by the conventional manufacturing method. A pressure molding machine that completely maintains the required basic characteristics, such as reliability against changes over time, and also maintains the special functions that were inevitably required in conventional manufacturing methods. It can be easily manufactured using a general pressure molding machine without using a pressure molding machine that holds the auxiliary drive part in the center, and the capacity of the equipment is utilized without wasting it. This completely eliminates the need to install pressure molding machines with special functions and increase prices due to larger equipment, making it possible to provide products at low prices without being constrained by the size of the shape. The practical effect is extremely large.

In explaining the present invention, the glass used is lead-containing low-melting glass, but it goes without saying that it is by no means limited to this type of glass, and commercially available enamel for ironware may be used. Needless to say, medicine can be used.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view showing the structure of a conventional insulated pipe joint, Figure 2 is a vertical cross-sectional view showing a conventional manufacturing method for small-shaped products, and Figure 2a is just before pressure forming. FIG. 2b shows the state after pressure molding is completed. FIG. 3 is a longitudinal cross-sectional view of the present invention, with FIG. 3a showing the state after pressure molding is completed, and FIG. 3b showing the manufactured structure after machining. FIG. 4 is a vertical cross-sectional view showing the manufacturing method of the insulated pipe joint shown in FIG. 3, and FIG.
Figure b shows the state after completion of pressure molding. In the figure, 1 is a first tubular member, 2 is a second tubular member, 2-2 is an outer peripheral fitting, 3 is a space, 4 is an insulator, 5 is a wall, 6 is a frame, 7 is a holding base, 8 1 is a support base, 9 is a pressure metal, 10 is a push metal, 11 is a drive unit, 1
2 is a preform, 13 is an arrow indicating floating pressure, 14
is the deletion part. Note that the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A first tubular member, a second tubular member having an outer peripheral fitting having an inner diameter larger than the outer diameter of the tubular member at one end of the tubular member having the same inner and outer diameters as the inner and outer diameters of this tubular member. , a gap is formed between the outer peripheral surface of the first tubular member and the inner peripheral surface of the outer peripheral fitting of the second tubular member, and the central axes of the first and second tubular members are aligned. , a step of inserting the first tubular member into the outer peripheral fitting of the second tubular member and bringing the end surface of the first tubular member into contact with the second tubular member; A step of press-fitting a raw material to become an electrically insulating glass-mica plastic body into the gap and forming it, removing a portion where the first tubular member contacts the second tubular member by machining,
A method for manufacturing an insulating pipe joint, which includes a step of exposing the molded plastic body.