JPS6021135A - Continuous production of multi-layered pipe - Google Patents

Abstract

PURPOSE:To obtain continuously a multi-layered pipe having the silencing function effective for radiation sound by maintaining the reduction rate of rolls in a specified range in the stage of forming the double pipe or the multiple-layered pipe provided with an interposing material by electric welding. CONSTITUTION:An interposing material 6a of glass wool, etc. is inserted into the space part between metallic hoops 1a and 2a for inside and outside pipes to form a three-layered blank material hoop. The hoop is then fed to a forming roll array and is then fed to squeezing rolls 11, by which the hoop is formed to a pipe shape. The electric weld zone 14 thereof is welded by welding devices 9, 10. The reduction rate of a shaping roll array is made <=1.5% in the stage of shaping the pipe with said array. The composite double steel pipe or the like effective for decreasing radiation sound when used for the exhaust pipe of an automotive engine, etc. is continuously formed with high accuracy by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously manufacturing a composite double steel pipe that is used for the exhaust pipe of an automobile engine and is effective for reducing exhaust pipe noise.

The exhaust pipe that connects the manifold of an automobile engine to the silencer has high temperature and pulsating pressure exhaust gas flowing through the pipe, so the noise generated by the engine's mechanical vibrations is transmitted through the exhaust pipe, etc. Both the noise generated by the vibration of the pipe itself due to the pulsating exhaust gas are dissipated into the surrounding area. Automobile noise can be broadly divided into power noise and running noise, and the former is caused by the engine noise, lassoator fan, exhaust gas, etc.
The latter is caused by rolling contact between the road and tires and the wind blowing through the vehicle body, and exhaust pipe noise is said to account for about 14% of the former. Therefore, in order to realize low-noise automobiles, research and development is underway on steel pipes for exhaust pipes that emit less noise.

A double steel pipe shown in FIG. 1 has been developed as one of the exhaust pipes that emit less noise. Figure 1(a) shows the inner tube 19 and outer tube 2.
(b) is the same, but the inner and outer tubes 19 and 20 are connected by directly touching each other at part A. It differs from (a) in that it is (welded). (C) is a double tube with inner and outer tubes 19 and 20 separated by a gap 22, and both ends B and C are connected. According to the test results, although the products (a) and (b) have the effect of reducing radiated sound at room temperature, the effect is drastically reduced at high temperatures.

On the other hand, the method (c) has less thermal influence, but has little reduction effect to begin with. Moreover, in the case of (c), the inner and outer tubes must be connected at both ends or at an appropriate intermediate point (if they are not connected, the inner tube will come out of the outer tube during handling), making processing difficult. So, when bending the pipe again, in part 1\,
There is a problem that the outer tube is deformed and the air gap 22 cannot be secured. In this point (a) and (b), the intervening material 18
Since the pipes are tightly packed, there is no risk that the inner and outer pipes will come into contact with each other even when bent, but the problem of insufficient noise reduction, especially at high temperatures, is a very serious problem when used as an exhaust pipe.

According to research conducted by the present inventors, it has been found that the filling state of the intervening material is a problem in composite double pipes in which an intervening material is packed between the inner and outer circumferential tubes. In other words, the intervening material needs to be fairly thick to absorb or shield the noise generated in the υ inner pipe due to pulsating exhaust gas, and if it does so, the pipe diameter will become too large to handle. Become. The interposition material can be made as thin as 1 mm or less, with the purpose of not only absorbing and insulating sound but also acting as a dampener against pipe vibration.
Although it is called a double pipe, it looks no different from a single pipe.

However, a double pipe in which an ultra-thin intervening material is densely packed between the inner and outer pipes as shown in Figures 1(a) and (b) has relatively good low-frequency sound scattering properties at room temperature. However, when the temperature rises, the sound emitted becomes like a dog. Exhaust pipes reach high temperatures of 600 to 800'C as high-temperature exhaust gas flows through them, so it is not desirable for exhaust pipes to emit sound from people at high temperatures.

The reason why the emitted sound becomes a dog at high temperatures is that thermal expansion puts strong pressure on the intervening material, which in turn causes both the inner and outer pipes to come into close contact with each other and become one piece. This is understood to be due to vibration. In order to prevent this, we came up with the idea that it would be better to have the insert material relatively loosely clogged, so that the two tubes vibrate independently, and in addition, be damped by the insert port. We made a prototype material for the splint and conducted experiments, which yielded good results.

By the way, there are several methods for inserting the insertion port between the inner and outer circumferential tubes. The first step is to weld both edges of the IJ sol by inserting a band-shaped intervening material between the two inner and outer pipe strips of a specified width and bending it into a cylindrical shape in the same way as for making electric resistance welded pipes.
In addition, an inner and outer tube with a relatively large difference in diameter is prepared, an insertion hole is attached to the outer circumference of the inner tube, the winding is done evenly, and then the tube is inserted into the outer tube, and then drawing is performed. There is also a method in which the outer tube is brought into close contact with the inner tube using an intervening material. In any case, a considerable compressive force acts on the insert material during the manufacturing process, and the insert material is filled between the inner and outer tubes under strong pressure. There was naturally a limit to the ability to create a composite double-walled steel pipe that could be integrated, shunted, and effective against radiated sound.

Therefore, as a result of various studies, the present inventor has found that when forming a double pipe or multilayer pipe into an ERW pipe and shaping it into a tubular shape, if the amount of roll glue reduction for shaping is set within a certain range, the inner and outer It was found that the tubes did not fit tightly together and were significantly effective in reducing radiated sound.

In the present invention, the inner and outer tube forming strips are stacked, or the intermediate layer strip and the inner and outer tube forming metal strips are stacked to form a double tube or a multi-layered tube by electric resistance welding to form a tubular shape. To provide a continuous manufacturing method for a multi-layered sound-deadening pipe, characterized in that during shaping, a sound-deadening function is imparted by reducing the amount of glue on the shaping roll to 1.5 or less.

This is because after forming the ERW pipe, two to five reductions/yongs are usually performed using shaping rolls to shape the formed pipe, but in this case, the inner and outer pipes come into close contact and are integrated. As a result, the degree of freedom of the inner tube, the intervening material, and the outer tube is reduced, and there is a problem in that the vibration damping function for suppressing friction between the inner and outer tube walls is degraded. Therefore, we used a narrower strip than the predetermined strip to make the ERW pipe in advance, and the shaping roll glue reduction was 1.5%.
By doing the following, the tightness of the inner and outer tubes is relaxed, the degree of adhesion is also reduced, and the wall where the inner tube, interposition material, and outer tube are in contact [)
This is a method for manufacturing a double pipe or a multilayer pipe that increases the number of degrees of freedom of 11, generates a friction phenomenon, converts vibration energy into thermal energy, and imparts a vibration damping function effect. The present invention will be described in detail below based on an example of an apparatus for carrying out the present invention.

FIG. 2 is an overview diagram showing a manufacturing line for multilayer ERW pipes.

In the figure, reference numeral 1 denotes an uncoiler for the metal strip coil for forming the inner tube. Reference numeral 12 denotes an uncoiler for the metal strip coil for forming the outer tube, and the tip is provided at an appropriate position at the entry of the electric resistance welding tube mill. Reference numerals 6 and 4 denote metal strip welding machines, respectively, which are installed at appropriate locations on the feed line for the unwound metal strips 1a and 2a for the inner tube and the outer tube. Reference numeral 5 denotes a looper, which is provided at an intermediate portion between the metal strips 1a and 2a feeding lines.

6 is an uncoiler for the intervening material, preferably
When forming the inner and outer tubes, the insert material unwound between the guide rolls 7 at the entrance of the molding r+-rule (r) is used to form the inner and outer tubes.

It is provided at the joint surface of the outer tube, that is, at the part where the intermediate layer is formed. Reference numeral 8 denotes a forming roll row, which has a known configuration for forming electric resistance welded pipes. 9 is a welding coil, 1o is a high frequency power source, and 11 is a squeeze roll. 12 is a multi-layered pipe (erw stitching)
In the case of a pipe, 16 is a row of shaping rolls for finishing the pipe to predetermined dimensions.

When making pipes, the metal strips 1a and 2a for the inner and outer pipes (the width of these strips is of course larger for the outer pipe) are unwound from the respective uncoilers 1 and 2. After welding the tail end of the preceding coil and the tip of the succeeding coil using the metal strip welding machines 6 and 4, they are superimposed and fed into the loop i95. The metal strips 1a and 2a that have passed through the looper 5 are connected to the inner pipe metal strip 1a between the looper outlet and the guide roll 7.
The metal strips 2a for the inner tube and the metal strip 2a for the outer tube are separated at appropriate intervals, and the insert material 6a, such as glass wool, is unwound from the insert material uncoiler 6 provided in the space created by the tear, and the metal strip 2a for the inner tube and After being inserted between the metal strips 1a and 2a for the outer tube to form a six-layer material strip (composite strip), it is fed into the forming roll row 8 via the guide roll 7.

The composite strip that has passed through the forming roll row 8 is squeeze roll 1
1, and is formed into a tubular shape at and X, and the electric resistance stitched portion 14 is welded by an attached welding device 9.10.

FIG. 6 shows the relationship between the squeeze roll and the welding device. That is, the tube-shaped strips 1a, 6a, 2a are heated as they pass around the impeder 15 and further through the welding coil 9 of the welding device, and pass through the squeeze roll 11 to form the electric resistance welded tube 12. The tube is then shaped by the shaping roll row 16 to produce a multilayer (erw welded) tube having an allocating function.

FIG. 4 is a sectional view showing an embodiment of a multilayer tube made by the method described above. 16 is a weld bead of the inner tube 19, 17 is a weld build of the outer tube 2o, and portions corresponding to the inner circumferential surface and outer circumferential surface of the multilayer tube are removed in a subsequent process. Also 1
8 is an interposition material.

In the above embodiment, the intervening material uncoiler 6 is installed between the looper 5 and the guide roll 7, but the present invention is not limited to this, and it may be installed alongside metal strip uncoilers for inner tubes and outer tubes, for example, as mill entry equipment. It is also possible. Furthermore, the metal strips for the inner and outer tubes can be wound twice and installed as a single coil in a mill entry uncoiler. Furthermore, although the example of the glass school was given as the above-mentioned intervening material, the present invention can also be used for sound insulation, heat insulation, heat retention, and vibration damping.

Any material, organic or inorganic, can be used as long as it has at least one type of excellent performance such as insulation and can be formed into a strip shape. Furthermore, in the method of the present invention, in a separate area outside the mill entry, a composite material is prepared in advance in which an intervening material is used as an intermediate layer and metal strips for forming inner and outer tubes are superimposed on both the front and back surfaces of the intervening layer. Of course, it is also possible to manufacture a multilayer pipe by electric resistance welding using a coil as a starting material.

An embodiment of the present invention will be described below, taking as an example a muffling pipe (multilayer pipe) used as a measure to reduce automobile exhaust noise.

(1) ERW pipe dimensions Outer diameter 75mm (2) Material Outer tube strip: Mild steel Inner tube strip: Mild steel intermediate layer strip Nigelas wool (4) Pipe making speed: 30 m/tread (5) Welding room crab 210KIv (6) Shaping torque conditions: Reduction amount 0.6% The silencing effect (at normal temperature) of a silencing tube (multilayered tube) manufactured under the above manufacturing conditions using the equipment shown in Figure 1 was compared with the conventional example. A comparison is shown in FIG.

In FIG. 5, ■ is a mild steel single tube, ■ is a ferritic stainless steel tube, and ■ is a mild steel double tube. FIG. 6 shows how the noise reduction function increases when the shaping roll glue reduction k is set to o-4 to 1.5%. The method for measuring the damping performance of the pipes shown in FIGS. 5 and 6 is as follows.

(B) External vibration (impact sound) A test tube (silenced tube) is struck with a constant force by a hammer, and the noise (A characteristic) is measured with a sound level meter at a position 1 m away from the opposite side of the tube.
:Measure.

(b) Put a steel ball in an internal vibration test tube (silence tube), rotate the tube itself, and measure the generated internal noise with a sound level meter at a position 17y1 away from the tube (A characteristic). .

As is clear from Fig. 5, the silencer pipe made according to the present invention has an approximately 1.
Furthermore, Fig. 6 shows a multilayer pipe with an intermediate layer material as the intervening material, and the state before heating without applying any thermal influence when changing the amount of glue reduction of the shaping roll. , which shows the internal vibration test values after heating to 600°C for 2 hours, and as is clear from this figure, when the amount of retraction was reduced to 1.5% or less, the damping performance was significantly improved.

The present invention can be applied to continuous manufacturing methods for pipes that require sound insulation (silence, soundproofing), heat insulation (heat retention), etc. For example, for sound insulation, exhaust pipes from automobile engines, air supply pipes in apartments, etc.・Used for the continuous production of pipes used for various heat exchanger piping and heat insulation rollers, such as drain pipes, motor covers, slurry pipes, pneumatic pipes, and conveyor rollers.

When the present invention is used as described above, in the continuous production of multilayer pipes, smooth feeding of the striations and highly accurate pipe production are achieved, and the effect of contributing to improved productivity and quality is extremely large.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional example diagram of a hollow double pipe and a multilayer pipe;
The figure is an overview diagram showing a production line for multilayer (ERW) pipes, FIG. 3 is a perspective view showing a welded state of the ERW pipe, and FIG. 4 is a cross-sectional view of a multilayer pipe manufactured by the present invention - an example diagram. Figures 5 and 6 are diagrams showing the damping performance of the silencer pipe. 1... Uncoiler of metal strip coil for forming inner pipe - 12
- Uncoiler for metal strip for forming outer tube - 11a - Metal strip for inner tube, 2a... Metal strip for outer tube, 6, 4 - Welding machine,
5. Roots =, 6. Uncoiler for insert material - 16a.
...Interposition material, 7.. Guide roll, 8.. Forming roll row, 9.. Welding coil, 10.. High frequency power source, 11.
・Squeeze roll, 12・Multilayer pipe, 16... Shaping roll row, 14... Electric resistance stitched part, 15...-Impeder, 16.17... Weld bead, 18... Interposition material, 19
- Inner tube, 20...Outer tube, 22...Hollow part.

Claims (1)

[Claims] After the metal strips for forming the inner and outer tubes are overlapped, or the intermediate layer strips serving as the intervening material and the metal strips for forming the inner and outer tubes are stacked to form an ERW tube, the reduction amount is reduced to 1 with a shaping roll row. .5
A continuous manufacturing method for a multilayer pipe, characterized in that a noise reduction function is imparted by making the pipe less than or equal to H.