JPS60132199A - Manufacture of insulating pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a method for manufacturing an insulating tube, and relates to a method for manufacturing an insulating tube having an insulating snout made from a glass-mica plastic body. It is related to this.

[Prior art]

Karasuma 12J plastic body is made from a mixture of glassy powder and mica powder, and this raw material powder is
It is an insulator obtained by heating to a temperature at which the glassy substance inside becomes soft (flowing under pressure) and then being pressure-molded in the heated state.

In recent years, a so-called cathodic protection method, in which electric potential is persistently applied, has become widely used in various fields to prevent corrosion of metal pipes for transporting gas or liquid. There is a question of whether this treatment will provide sufficient corrosion protection, but on the other hand, there is a risk of disaster occurring due to the applied potential.To prevent this,
In the dangerous area, an insulating tube to which no potential is applied is interposed between metal tubes. The insulating tube mentioned here is for personal use.

The atmospheric conditions in which the metal pipe for conveyance is arranged are extremely diverse, and severe conditions include temperature conditions of 200 to 300° C., polluted water, seawater, and the like. Also,
Joining of metal tubes and insulating tubes is often carried out mechanically on-site, mainly using backing materials and screws.

Insulating tubes used under the above conditions are inevitably required to have many properties, the main ones being high electrical insulation resistance, and especially the length necessary to ensure creeping insulation properties. Even when the temperature reaches 200 to 300°C, the insulation resistance does not decrease, the mechanical strength does not decrease, and the material does not deform.

In addition, the coefficient of thermal expansion is similar to that of a metal tube, so even if the temperature repeatedly rises and falls, it maintains a perfect bonded state and does not cause leakage phenomena. Must have great mechanical strength and cold and mechanical impact strength. It should have excellent corrosion resistance and be non-porous. It is easy to machine, and products with precise dimensions necessary for mechanical joining can be obtained at low cost.

When choosing an insulating tube that has the above characteristics, the selection conditions are severely restricted. First of all, it is generally used as an insulating tube (・Rumo σ) made of organic material, and peak resin is also used as material with rich near-side thermal characteristics σ−). It has become so. The insulating tube made of this peak resin has excellent electrical, mechanical, heat resistance, and other properties (membrane properties), and has a thermal expansion coefficient of 5 to 70 times that of a gold bullion tube.
It is large and deforms greatly when the temperature rises. Therefore, when used for insulating tubes for the above purpose, the sweat rate is 1.200 to 300″C.
If the temperature rises and falls repeatedly, the bonding state will be destroyed and a leakage phenomenon will occur. This is a fatal defect as an insulating tube for the above purpose and cannot be used.

Next, there is the porcelain insulation tube. σ) Things are electrical,
Thermal expansion coefficient, air impermeability, corrosion resistance, etc. (℃) However, it is not easy to machine and is extremely expensive to obtain products with precise dimensions. Therefore, it is impossible to use porcelain pipes as insulating pipes for the above purpose.

In this regard, insulating tubes made of glass-mica plastics have good mechanical and electrical properties, with no deterioration in properties even at temperatures of 20θ to 300℃, excellent cold and mechanical impact strength, corrosion resistance, and non-ventilation. In addition to maintaining its properties, its coefficient of thermal expansion is similar to that of metal pipes, so it always maintains a perfect bonded state even when the temperature repeatedly rises and falls.It is also necessary for bonding because it is easy to machine. It has ideal characteristics as an insulating tube used for the above purpose, such as easily obtaining products with precise dimensions.However, as will be explained next, conventional manufacturing methods do not allow long insulating tubes to be manufactured. This makes it impossible to use under conditions of use that require long products to ensure bath surface insulation resistance, and the product itself deteriorates due to the unavoidable sweating associated with the manufacturing method. When it became extremely expensive (there was a flaw similar to Umaki Kinuta).

In order to facilitate understanding of the present invention, the characteristics of the mica-glass plastic body and the conventional manufacturing method of this type of insulating tube will be explained below before giving a detailed explanation of the present invention.

First, the characteristics of the glass-mica molded body are largely determined by the characteristics of the raw material glass used.

For example, in terms of heat resistance, the glassy dislocation temperature force tI
o o "C" (using the one of l, 3Qθ"c a
It deforms even when the temperature reaches +, and not only is it good, but its electrical and mechanical strength (knee) remains almost unchanged,
Maintains characteristics that are not significantly different from those at room temperature. Furthermore, the controlling force of the coefficient of thermal expansion is very strong, and by controlling the characteristics of the glassy substance, a coefficient of thermal expansion of 3 to 10-' can be obtained.

Next, regarding raw material 71, natural mica is not preferred as a raw material mica because it contains crystal water and has a low thermal decomposition temperature, and there are many varieties and it is difficult to obtain stable custom-made products. In this respect, synthetic mica does not have the above-mentioned tendency, has a high heat resistance and is always stable, and is easily available as a custom-made product. Therefore, synthetic mica powder is used exclusively, and synthetic fluorine-containing gold-collecting mica is particularly suitable.

Now, FIG. 1 shows an insulating tube 1 made of a glass-mica plastic body obtained by a conventional manufacturing method.

Next, an example of a conventional manufacturing method will be explained with reference to FIG.

A mold is used for manufacturing. The mold for molding is a frame,
It is composed of the following t parts: a partitioned wall part 3 having a raw material loading chamber 3a on the upper part, a supporting metal part having a convex part IIa for holding the core metal fitting 6 in the center, and a pressurizing metal part S.

The raw material glass has a component composition of PbO near 0. BO'ko 3
auto/b + sto, :/+ W%, and the dislocation temperature is q
The material at o o °C is ground into SOO mesh and used. The raw mica is synthetic fluorine-containing gold-collecting mica powder with a viscosity of 6.
Use a mesh of 0 to 10θ. glass powder SO
A raw material powder is prepared by mixing W% and mica powder 5ovr%, approximately tW% of moisture is added to the raw material powder to make it moist, and the raw material loading chamber 3a is formed by cold pressing (the mold is not shown). After being formed into a cylindrical body that can be loaded into a container, the preformed body 7 is dried to remove moisture and used as a preformed body 7.

For molding, the frame, wall 3, and support metal DA of the mold are assembled as shown in FIG. 2(a), and the pressure metal S is not assembled, and the core metal fitting 6 is heated to 1.00° C., and the preform 7 is heated to goo° C., respectively. When the biasing is completed, the core metal fitting 6 is loaded onto the support metal q in the wall portion 3, and then the preform 7 is loaded 1' into the raw material loading chamber 3-/. The current state is shown in Figure a←). Next, the pressurized metal S is placed on the preformed body 7, and the pressurized metal J is pressed by a pressure molding machine (not shown). Press fit into the constituting space g1. Then, the insulator 9 is formed. The state at this time is shown in Fig. 2 (7r:(-) in bl).

Cool the insulator wa until the temperature reaches 3 gθ°C (a temperature lower than the transition temperature of glass) 7, disassemble the molding die and take out the molded product, cut and remove the core fitting 6 by machining, Manufacturing is completed by finishing the insulating tube l shown in FIG.

However, as mentioned above, when using the conventional manufacturing method of pressure forming in the length direction of the insulating tube, short length insulating tubes can have ideal characteristics, but The unavoidable fatal flaw was that it was impossible to manufacture products with favorable characteristics if the length was long. The reason for this will be explained below. The raw material, a mixture of vitreous and mica powder, has an extremely high viscosity even when heated, and this viscosity is largely controlled by temperature; Then, it increases rapidly. The heating temperature of the preformed body 7 during molding should be adjusted (this will lower the viscosity, but as the temperature rises, the erosion of glassy mica becomes more intense, so there is naturally a limit to the heating temperature. .

~ g s o ”c is the limit. Also, the molding die is
The heating temperature is related to the intensity.1. Sso "C: is the limit. Therefore, during pressure molding, the preformed body 7 that has been pressurized by the pressurizing metal S flows into the space g, but it comes into contact with the wall 3 and the temperature rises. When the viscosity decreases, the fluidity deteriorates because the viscosity rapidly increases, and when the length of the product becomes long, the tip qa is not completely filled and the density does not increase.

Therefore, it is not possible to mold the insulator 9 in a uniform state.

Since the above phenomenon is an unavoidable condition, a long product cannot be obtained, which is a fatal flaw in the conventional manufacturing method. In addition, in this conventional manufacturing method, a process of machining the molded product to cut and remove the core metal fitting 6 is required;
This work is difficult and requires considerable effort. This led to an increase in price and was one of the major drawbacks.

[Summary of the invention]

This invention was made with the aim of completely eliminating the drawbacks of the above-mentioned conventional methods. It facilitates the production of long insulating tubes, and also eliminates the need for conventional machining of molded products, resulting in lower costs. The present invention provides a method for manufacturing an insulating tube that can be obtained at a low price.

In the present invention, which achieves the above objects, a core metal having a taper on the outer periphery is arranged coaxially with the through-hole formed horizontally in a molding die, and the raw material of the glass-mica plastic body is The feature is that the one-piece molded body is pressed perpendicularly to the longitudinal direction of the insulating tube to be molded.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 to 6.

First, the structure of the mold used in the manufacturing method of the present invention will be explained with reference to FIG. 3(a) and FIG. The molding die is composed of a molding part and a pressurizing metal. Molding part A
consists of a bottom metal 10, a bottom metal//and a base metal 1303 portion having a split structure, and the contact surfaces of the stacked metals have a mechanism that prevents insulators from flowing out during molding. A rectangular raw material loading chamber /4' is provided in the upper part of the lower metal 10, and a rectangular groove-shaped outlet passage 15 is provided in the lower part thereof, penetrating from the bottom of the raw material loading chamber /4' to the lower surface. The lower metal // has nine horizontal through-holes 16 in the center, a filling passage 17 of the same shape that communicates with the lower metal outlet/jK in the upper part, and a through-hole l in the lower part. A rectangular groove-shaped flow path ig and a reservoir 19 are provided below the flow path ig, respectively. The lower plate/l is the upper part 12-7 and the lower part/, 2-. 7. It can be divided into The base metal /3 is located at the bottom of the lower metal /l, and the lower metal i
o and lower money // are fixed. The pressurizing metal fitting θ has a structure that fits into the raw material loading chamber.

The molding jig unit installed in the through hole 16 is shown in Fig. S. The core metal here has a center hole 23 in the center, the outer periphery is tapered 2'l, and the outer periphery of the thick part Diameter is side plate 2S
It is smaller than the outer diameter of Thermal expansion coefficient of constituent materials (
In this case, it is the thermal contraction coefficient, but it will be referred to as the thermal expansion coefficient from now on)
is larger than the thermal expansion coefficient below the transition temperature of the raw material glass of the insulator made of the constructed glass-mica plastic body. Stainless steel, copper alloy, etc. are preferably used. The outer diameter of the side plate 25 is large enough to fit into the through hole 16 of the mold. There are no restrictions on the percentage in terms of material. A bolt λ6 is inserted into the center hole 3, and a washer 27 and a nut 2g are inserted.
Then, the core metal is held concentrically with the side plate 2S and assembled as shown in FIG. The material used for the bolt 2B has a coefficient of thermal expansion smaller than that of the core metal 22, and titanium or the like is preferable. The washer 27 may be any suitable material such as a disc spring or a spring washer, and serves to hold the core bar 22 and the side plate 2S concentrically and to assemble the nut 2g without applying strong tightening pressure.

Next, the manufacturing process will be explained. The raw materials used are the same as the conventional method.
A plate-shaped preformed body 29 that can be loaded into the raw material loading chamber 1lI- is prepared using a similar material.

For molding, the integrated molding part A and pressurized gold plate O are heated to SSO℃.
Then, the molding jig 21 was heated to 200°C, and the preform, 2
Heat q to 200°C.

When heating is completed, the molding jig 21 is inserted into the through hole 1 of the bottom metal.
6 and is fitted and held by the side plate 2S. Next, the preform 29 is loaded into the raw material loading chamber/4. The state at this time is shown in FIG. 3(a) and FIG. q(a).

Next, the pressurized metal 20 is placed on the preformed body 29, and the pressurized metal 20 is pressurized by a pressure molding machine (not shown) to cause the preformed body 29 to flow. The preformed body 29' passes through the outflow path /j and the filling path 17, and enters the space 30 formed by the core bar 22 of the molding jig 2/, the side plate 2S, and the through hole 16 of the bottom metal l/.
reach. When the flowing preform material reaches the upper part of the core bar 2J, it branches left and right and flows, filling the space 3O adjacent to the side plate 25, and then collides and coalesces at the lower part of the core bar 2.2, The combined part passes through the flow path 7g, fills the reservoir part/di, and stops flowing. Thereafter, the density of the preformed body 29 increases due to the pressure applied by the pressurizing metal 20, and the glass-mica plastic body ρ・An insulator 3/ is formed.

The state at this time is shown in FIG. 3(b) and FIG. 1(b). Then, the insulator 3/ is cooled until the temperature reaches 380° C. 7, and the molding die is disassembled and the molded product is taken out. The thin plate-shaped insulators 3/1S+ formed in the outflow path 15, the filling path 17, and the flow path tg will affect the predetermined insulator 31 formed in the space 30t1. , Figure 6 (a molded product can be obtained without the moon ζ).

Finally, first, the surface of the insulator 31 is finished by machining into a smooth surface with fixed dimensions.The glass-mica plastic body is easy to machine and can be finished with a cutting tool. Loosen the nut 2g and remove the side plate 2S, washer 27, and bolt 2B.Since the coefficient of thermal expansion of the core bar 22 is larger than that of the insulator 3/ at the transition temperature of the raw glass below θO℃, , the core metal 22 exhibits a shrinkage phenomenon in both the circumferential direction and the axial direction, and a gap is generated between the outer peripheral surface of the core metal 22 and the inner peripheral surface of the insulator 3/. Since the taper 21I is provided, the core metal here can be easily removed, and the insulating tube 32 shown in FIG. 6(b) is obtained. This completes the manufacturing.

The features of the manufacturing method according to the present invention and the three insulating tubes made of glass-mica plastic bodies that were manufactured will be described above. In the case of this manufacturing method, the length of the flow path of the heated preform 2q is short because it is in the circumferential direction of the space 1%3o.
There is almost no difference in the density of each part. In particular, the molding mold has a flow path/g and a reservoir l? is provided, and the preformed body Uta flows by branching to the left and right of the core metal of the molding jig 21, and as a result of this flow, the colliding and coalescing portion at the leading end where the temperature has decreased is completely removed, and the insulator 31 is molded, so
Since the condition is completely uniform over the entire length, no cracks occur at all. This distribution w1/
g and the reservoir 19 are unavoidable conditions under the manufacturing conditions of this insulating tube. In addition, although the filling channel 17 is shaped like a groove in the embodiment, it is not limited to the shape of a groove, but can be made into an outflow hole or a light filling hole, and a plurality of these may be installed. There is no problem.

Next, regarding the length of the product, even if it becomes longer, no conditions will occur that would change the above conditions, so long length molding is easily possible, and the problem is detailed next. Only the core bar 22 is removed.

Next is the problem of removing the core bar 22 from the molded product to obtain the insulating tube 32, which is largely related to the molding jig 21.

When obtaining long products, it is necessary to consider the following conditions.

First, the difference in thermal expansion coefficient between the core bar 22 and the glass-mica plastic body should be made as large as possible, and the second purpose is to increase the taper 24/ and to avoid the occurrence of the phenomenon of close contact between the core bar 22 and the insulator 31. .

There are some restrictions on the selection of the material for the core metal, so the most effective way to increase the difference is to reduce the coefficient of thermal expansion of the insulator.

Increasing the taper 2'l will result in a difference in wall thickness at both ends, but this can be done by grinding the inner peripheral surface of the thicker part by machining to create an insulating tube with equal wall thickness after forming. It is possible to finish it. Furthermore, regarding the issue of adhesion between the core metal and the insulator 31, using a copper alloy is a useful method. In the case of copper alloys, a copper oxide film is formed on the surface when heated, but since this film hardly adheres to the base metal, it exerts the effect of a template agent.

In addition, in the forming jig 21, the use of a material with a small coefficient of thermal expansion for the bolt 2B and the use of the washer 27 to skillfully reduce the tightening pressure of the nut and zg are important after forming. This is a measure to prevent tightening pressure from being applied to the insulator 31 formed by the side plate 2S during cooling.

〔Effect of the invention〕

By using the manufacturing method described above, this invention has the advantage that insulation resistance and mechanical strength do not decrease and deformation does not occur even when the operating temperature reaches 200 to 300 degrees Celsius. However, the insulated tube always maintains a perfect connection state without causing any leakage phenomenon, and also maintains great cooling and thermal strength and mechanical strength. While maintaining properties equivalent to those of conventional products, it is possible to manufacture long products that could not be obtained using conventional manufacturing methods. 6-sided insulation resistance is completely ensured, and when used in seawater or polluted water, ρ・L
I became LJ friend.

As mentioned above, all the drawbacks of the previous method have been completely eliminated, making it possible to use it in a wide range of Hue provinces, and its effectiveness is extremely high. Note that the effects are not limited to this aspect; another useful effect is that the price has been greatly reduced, and its practical and technical value is extremely large.

In the above explanation, we have mainly focused on insulating tubes interposed in the middle in front of metal for corrosion protection, but the use of these insulating tubes is not limited to this, and corrosion-resistant insulating tubes in chemical factories. The scope of its use is extremely wide, such as heat-resistant insulated tubes used in high-temperature parts such as automobiles that are subject to vibration.

[Brief explanation of the drawing]

Fig. 7 is a longitudinal cross-sectional view of a conventional insulating tube, and Fig. 1 is a longitudinal cross-sectional view explaining the conventional method.
The same figure (b) shows each after completion of pressure molding. Figures 3 to 6 are diagrams for explaining one embodiment of the present invention, and Figures 3(a) and 9(a) are longitudinal sectional views and transverse sectional views, respectively, immediately before pressure molding, and Figures (b) and 7(b) are a longitudinal cross-sectional view and a cross-sectional view, respectively, after completion of the oral pressure molding, Figure S is a longitudinal cross-sectional view of the molding jig, Figure 6fa), (bi before removing the molding jig,
A vertical cross-sectional view of the molded product afterward is shown. /θ...L gold, //...lower metal consisting of upper part /2-/ and lower part 12-2, 13...base metal, /ll...raw material loading, i!
・・Outflow path, lA・・Through hole, 17・・Filling path, 1g・
・Flow path, /9・・Reservoir part 1.20・・Pressure metal, ko/・
・Forming jig, 2λ°. Core metal, C3...center hole, 2hiro...taper, C S/° aim 1
1 Sulfur, 26...Bolt, Core...Washer, -g...Nut, 29...Preformed body, 3O...Space, 3/...Insulator, 3U...Insulating tube. In each figure, the same reference numerals indicate the same or corresponding parts. Showa 5g! f6. J] 7 Commissioner of the Japan Patent Office 1, Indication of the case, Showa SG Year Special Revision Application No. J9tJo No. 2, Name of the invention, Process for manufacturing insulating tubes 3, Person making the amendment (11) Detailed description of the invention in the J specification 6. Contents of amendment

Claims (2)

[Claims] (1) (a) A first step of creating a preform by cold-pressing a mixture of glassy powder and mica powder, and (b) A horizontal through-hole into which a molding jig is to be fitted. A lower metal plate is provided with a filling path in the upper part of the through hole and a reservoir part via a flow path in the lower part and is separable, and a lower metal part is provided with an outflow path communicating with the filling path in the lower part and is engaged with the pressurized metal part. a first step of preparing a molding die comprising a preform loading chamber and a stopper directly connected to the bottom die; A third step of preparing the molding jig comprising a core metal having a hole and a tapered outer circumferential surface, and a side plate that fits into the through hole at both ends of the core metal with bolts passing through the center hole. (2) heating the preform, the molding die, and the molding jig to respective predetermined temperatures, and fitting the molding jig into the through hole in the heated state; , the preform is loaded into the preform loading chamber and pressurized by the pressurizing metal, and the preform is flowed and filled into the space between the molding jig and the through hole and the reservoir. and (e) disassembling the molding die after cooling to take out a molded product including the molding jig, and then disassembling the molding jig to obtain a molded product. process, and a method for manufacturing an insulating tube using a glass-mica plastic body. (2) In the step S, the unnecessary portion of the molded product is removed by machining before disassembling the molding jig. (3) Dislocation of raw material glass A molding jig comprising a core made of a metal having a coefficient of thermal expansion greater than the coefficient of thermal expansion of a glass-mica plastic body at a temperature below the temperature, and a bolt made of a metal having a coefficient of thermal expansion smaller than the coefficient of thermal expansion of the core metal. Claim 1 which specifically uses the method described in claim 1. Method for manufacturing insulating tubes.