JPS586723A - Successive manufacture of heat-insulating multilayered pipe - Google Patents

Abstract

PURPOSE:To successively manufacture a composite pipe for motorcar exhaustion which has superior heat-insulating and heat-retaining properties by electrically seaming a mild band steel into a pipe, forming a heat-insulating layer around its external surface, electrically seaming and welding a stainless band steel, etc., to the outside of the layer, and reducing the diameter. CONSTITUTION:Bandlike mild steel 1a uncoiled from an uncoiler 1A is formed into a pipe shape by a train of forming rolls 5, and electrically seamed and welded by a high-frequency coil 6 to manufacture an internal pipe 1. After the internal pipe 1 is covered with a bandlike heat-insulating material 2a such as ceramic in a pipe shape, butt parts at both ends are fixed with an adhesive tape 16. This internal pipe 18 with the heat-insulating material coating is covered with a stainless band steel 3a, and the connection part is electrically seamed and welded by a high-frequency welding machine 23 to obtain an external pipe. This composite pipe is reduced in diameter by a roller group 29 for diameter reduction to obtain a composite pipe 30. Thus, an exhaust gap pipe for a motorcar which consists of the internal pipe 1 having the interposed heat-insulating layer 2 and the external pipe 3 is manufactured successively.

Description

[Detailed Description of the Invention] Honjitsu f! A relates to a method for continuously manufacturing a heat-insulating multilayer pipe used for automobile exhaust pipes and the like.

Exhaust pipes for automobiles are increasingly required to have various characteristics. One of them is insulation.

When the car is stopped, the exhaust pipe becomes very hot as it passes through engine exhaust gas with a temperature of 700 to 9,000 degrees Celsius while driving, and when the car stops, it becomes stationary against the ground, and if there is dry grass under the P1, it ignites it and causes a fire. Therefore, the outer peripheral surface of the exhaust pipe should be kept at a low temperature. As a countermeasure against this dry grass, a heat shield plate is installed, but since the heat shield plate vibrates during driving and becomes a source of noise, the exhaust pipe has insulation properties and the outer peripheral surface R cannot rise. It is hoped that Part 2
is heat retention. As is well known, a catalyst is used to purify exhaust gas, and catalysts are more efficient at high temperatures, so the exhaust gas is not cooled, so it is desirable that the exhaust pipe has heat retention properties.

In order to provide the exhaust pipe with heat insulation and heat retention properties, it is effective to form a double pipe and insert a heat insulating material between the pipes as shown in FIG. In this figure, 1 is a steel pipe made of ordinary steel, 2 is a heat insulating layer, and 5 is a steel pipe made of stainless steel or the like. As a heat insulating material, ceramic and porcelain are suitable since heat resistance of about 900°C is required. Thickness is required inside and outside the ZO from the viewpoint of heat insulation (for example, exhaust gas temperature [700° C. and exhaust pipe outer peripheral temperature [400° C. or less]) and heat retention. Exhaust pipes are required to have sound deadening properties and bendability, and during operation, the inner pipe becomes hot and expands, and when the operation is stopped, it cools and contracts. As a result, the insulation layer is particularly susceptible to frictional sliding caused by the inner pipe. Powder resistance is also required, as the material has a tendency to powder.

There are not many examples of such continuous production equipment for multi-layer pipes because multi-layer pipes themselves are relatively new. (4I request @54-50930).

This involves pulling out strips from the inner tube coil and outer tube coil, sandwiching a non-metallic strip such as glass coil between the two strips, rolling them into a tube shape, and welding the inner and outer tube strips together using high-frequency electric welding. , the outer tube.

However, with this method, a problem arises in the welded parts of the inner and outer tubes as a heat-insulating multi-layer tube. That is, there is a risk that the inner and outer tubes will not be separated but will be integrated at the welded portion, and if the inner and outer tubes are integrated, the insulation will deteriorate. It is conceivable to widen the width of the nonmetallic strip and interpose the strip welding for the inner and outer tubes to isolate them, but in this case, the nonmetallic strip is directly exposed to the high temperature during welding and thermally decomposes, causing gas to be released. Welding defects such as pits and play holes may cause noise. Note that the temperature of the welded portion reaches 1400°C or higher. Heat-resistant materials used as intermediate materials often contain binders, and these binders easily evaporate even at low temperatures.

In the present invention, the intermediate insulation material layer completely surrounds the inner tube and makes the inner and outer tubes independent, so that the inner and outer tubes are not damaged during welding, and good welding of the inner and outer tubes without defects is ensured. How to continuously manufacture insulated multilayer pipes? *The inner tube is made by electric resistance welding of strips drawn from the inner tube coil, and a gap is created around the outer circumference after the inner tube is coated with a heat-insulating intermediate layer material. In this way, the outer tube was made by electric resistance welding the strips pulled out from the outer tube coil.
The connection between the outer pipe and the middle layer material is made by drawing the multilayer pipe.
It's a matter of adjustment. Next, this will be explained in detail with reference to the embodiment shown in FIG.

In Figure 2, there is one person inside, an uncoiler for pipe coils,
The tip of the metal strip 1a pulled out from this uncoiler is first welded to the tail end of the metal strip of nine coils using a welding machine 12 to make it continuous, and after passing through a looper 13 and a leveler 41, it passes through a forming roll for an inner tube. The inner tube 1 is formed into a tubular shape in the row 5 and subjected to electric resistance welding at a welding section equipped with a high frequency power source 7 and a welding coil 6. 8 is a squeeze roll for the inner pipe, 9 is a welding bead cutting tool, and 10 is a bead cutting waste. Although not shown, the welding bead also cuts the inner surface. Next, reference numeral 2 is an uncoiler for the insulation coil for forming the intermediate layer material, and the insulation strip 2 drawn out from this uncoiler is formed into a tubular shape that wraps around the inner tube 1 by -14, and the insulation material strip 2 is drawn out from this uncoiler and is formed into a tubular shape that wraps around the inner tube 1. The edge abutments are fastened with adhesive tape 16. 15 is an uncoiler for adhesive tape 16; 117 is adhesive tape 16t; insulation material strip;
This is an adhesive roll that is pressed against the abutting portions of both side edges of the tape 2a.

The manner in which this inner tube 1t is wrapped with insulation material strip and glue 2a is ms
As shown in the figure. ~ No. 31N(a) is that the insulation strip 2a is the molded shoe 1
4 shows the relationship between the strip and the inner tube 1 when it forms a flat strip before entering the inner tube 1. When the strip 2a enters the forming shoe 14, it is gradually bent as shown in FIGS. 3(b) and 3(e), and eventually the abutting portion 2' comes into close contact with the inner tube 1, as shown in FIG. 3(d). When the strip 2a leaves the sea, there is a die in this part, so when the strip 2a leaves the die, the strip 2a becomes loose as shown in FIG. This is held down with a roll (not shown) to eliminate gears and glue, and tape 16 is pasted on the upper surface of the abutted portion as shown in (f). 18 shows the inner tube to which the insulation strip is pasted. The thickness of the insulation strip should be determined based on the purpose of insulation, heat retention, distribution, sound insulation, etc. ((L)
It is preferable that it is 5 swz to several ■. In addition, the insulation material is
It is necessary to ensure that the insulation material is placed between the outer tubes over the entire circumference so that the inner and outer tubes do not come into contact with each other due to local thinning or breakage, but this method of attaching the insulation material is sufficient. This requirement can be met.

Also, in Figure 2, three people are working on the metal strip for forming the outer tube.
In the coiler, the strip 3a drawn out from this uncoiler 3A is welded by a welding machine 20 and made continuous in the same manner as the strip 1&, passed through a looper 21, and formed into a tubular shape surrounding the inner tube 18 by an outer tube forming die and roll row 22. molded into
The outer tube 3 is formed by electric resistance welding at a welding section including a high frequency power source 24 and a welding electrode 25. Reference numeral 25 indicates a cutting tool for cutting the outer surface of the weld bead, and reference numeral 26 indicates bead cutting waste. 29 is a roll group that reduces the diameter of the outer tube 5 to set the distance between the inner and outer tubes to a predetermined value;
30 indicates a nine-layered pipe produced as described above. The outer tube forming roll row 22 has a shape shown in FIG. 4 in the front stage and as shown in FIG. 5 in the rear stage. In FIG. IF5, 22a is an outer tube forming roll which is provided on both sides of the inner tube 18 and at the middle and lower part thereof.The shapes of these left and right rolls are the same, and the outer tube strip 3ai is gradually formed into a tubular shape. FIG. 5 shows the latter rolls for forming into a substantially tubular shape, 22g is the lower roll, and 22c is the upper roll, each of which is equipped with fins 221. 22h.

22. is the axis of these rolls. The fin 22d is
#t! It is inserted into the gap between the abutting portions of both side edges of the tubular outer tube strip 3a, and guided so that the east metal flange portion is correctly positioned at the uppermost position. This is the chip 23 for the next process.
, the high-frequency power source 24 facilitates electric resistance welding. As shown in FIG. 5, a gap g is provided at the threshold between the outer tube 3a and the inner tube 1 with the heat insulating layer 2. This is to prevent the fins 22d inserted into the outer pipe abutment gear and puller from suppressing and deforming the inner pipe with the heat insulating material layer, and also to prevent welding heat from being transferred to the heat insulating material layer 2 and the adhesive tape 16 in the next welding process. This is effective in preventing direct damage to these materials. The diameter reduction by the roll group 29 is performed at this interval gt
As shown in FIG. 6, the heat-insulating double-knot tube 30 is tightly fitted with no gaps. The diameter is gradually reduced to the diameter of the outer tube shown in Figure 6, and the roll group (2
9 is like that).

In the manufacturing process of this insulated multilayer pipe, the inner pipe and outer pipe are formed and welded separately on the same production line, and the inner pipe is coated with a heat insulating material between the inner and outer pipes. The inner and outer pipes can be manufactured reliably, and the insulation material is subjected to strong pressure when forming the inner and outer pipe strips into the pipe body, resulting in thinning (for example, 2.0
The thickness of the material is not locally damaged (L2~(L4■)), and furthermore, the heat insulating material does not receive the inner pipe welding heat at all, and the outer pipe melting heat is transmitted through the interval g. Since the material is only exposed to a certain amount of heat, thermal decomposition does not occur, and furthermore, there is no possibility of poor contact between the inner and outer tubes.Examples will now be described.

An insulated multi-layer pipe for automobile exhaust pipes was manufactured in the following manner.

■Multi-layer pipe dimensions: Outer diameter 42.7■ ■Material: Strip for outer pipe --- Mild steel Strip for inner pipe --- Stainless steel intermediate insulation strip ---・Sayumi, Kusheet adhesive tape・
-...-Aluminum adhesive tape ■Material dimensions ■Pipe manufacturing speed 50 rt* / min Heat shielding of insulated multilayer pipe manufactured under the above manufacturing conditions using the equipment shown in Figure 2 Fig. 7 shows a performance comparison between a product manufactured by the conventional method (method of the above-mentioned application) and a single pipe using the same material with the same effect and heat retention effect.

A 700° C. gas was flowed into the tube, and the outer surface temperature of the tube was measured as a measure of heat shielding performance, and the outlet gas temperature was measured as a measure of heat retention performance. As shown in this graph, the tube outer surface temperature is about 48 in a single tube and 450° C. in the conventional method, whereas it is only about 340° C. in the method of the present invention. In addition, heat retention can be maintained at 645°C with the conventional method and 665°C with the present invention, whereas the temperature of a single tube is about 620°C.

As explained above, the present invention has the advantage of providing a continuous manufacturing method for insulating multilayer pipes that have excellent heat insulation and heat retention properties, ensure reliable welding of inner and outer pipes, have high quality, and can also be expected to improve productivity. can get. Although the multilayer pipe of the present invention is suitable for automobile exhaust pipes, it can be used not only for automobile exhaust pipes but also for various types of piping that require heat insulation and heat retention.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a multilayer pipe, Figure 182 is an explanatory diagram showing an embodiment of the present invention, Ims diagram is an explanatory diagram of the process of coating the inner pipe with the intermediate layer material, and Figures 4 and 5 are the outer Techniques for shaping pipes!
FIG. 6 is a cross-sectional view of the manufactured multilayer insulation pipe, and FIG. 7 is a graph showing the performance test results. In the drawing, 1& is the strip for the inner tube, 6.7 is the welding equipment for the circular tube, 2a is the strip for the intermediate layer material, g is the gap, 3& is the strip for the outer tube, 23.24 is the welding equipment for the outer tube, 29 is a row of rolls for drawing. Applicants: New and Old Patent Application, Tetsuko Co., Ltd. Nikai 1st Company Representative: Minoru Minoru, Minoru Sane Figure 3 Figure 451 Figure 6

Claims (1)

[Claims] A strip drawn from the inner tube coil is erect welded to form an inner tube, the outer periphery of which is covered with an insulating intermediate layer material, and a gap is then created around the outer periphery, and the strip drawn from the outer tube coil. An outer tube is made using an ERW mat, and the multi-layer tube is drawn to form a connection between the outer tube and the intermediate layer material.
To adjust? : Characteristic continuous manufacturing method for insulated multilayer pipes.