JPH0212657B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method and apparatus for increasing the thickness of a pipe material, and in particular, to increasing the thickness of a tube without irregular deformation such as wrinkles or buckling, and increasing the thickness toward the inner diameter side. The present invention relates to a method and apparatus for increasing the thickness of a pipe material with the aim of reducing the amount of wall material.

[Prior art]

BACKGROUND ART Conventionally, as a method for increasing the thickness of a tube, a method is known in which swaging is performed by applying a compressive force in the axial direction of the tube to increase the thickness of the tube.

FIG. 1 is a perspective view showing a pipe material whose thickness has been increased by a conventional method of increasing its thickness.

In this FIG. 1, 1 is a tube material, and 2 is irregular deformation such as buckling or wrinkles that has occurred in this tube material 1.

As is clear from Fig. 1, if the swaging process is performed only by applying compressive force, that is, by simple compression process, irregular deformation 2 such as buckling and wrinkles will occur in the pipe material 1, resulting in uniform thickening. Processing could not be achieved and this was the cause of defects.

The present inventors have previously proposed a method for increasing the thickness of a pipe, which eliminates the drawbacks of the prior art described above and can achieve uniform thickness increasing without irregular deformation such as buckling and wrinkles, and the implementation of this method. We developed a device that can be used directly for

The feature of the method for increasing the thickness of a tube that was previously developed by the present inventors is that while sequentially locally heating the portion of the tube to be increased, a compressive force is applied to compress the tube at a constant speed. By performing swaging processing, the thickness of the thickened portion is increased.

Further, the features of the thickness increasing processing device that the present inventors developed earlier include a stepping cylinder that can compress the tube at a constant speed in the axial direction using its spindle, and a stepping cylinder located on the outer periphery of the tube. The tube has an annular heating coil which is arranged as shown in FIG.

By using the above-mentioned apparatus previously developed by the present inventors, it has become possible to uniformly thicken the tube material without causing irregular deformation such as buckling or wrinkles.

By the way, in the above-mentioned thickness increasing process, the amount of thickness increase occurs on both the outer diameter side and the inner diameter side, but especially when the inner diameter of the pipe material is small, the increase in thickness on the inner diameter side will increase the amount of wall thickness of the fluid flowing inside the pipe material. There were problems that should be further improved, such as increasing the rate of decrease in flow rate and causing cavitation in that area, which could lead to corrosion during use.

[Purpose of the invention]

The present invention improves the above-mentioned problems and eliminates wrinkles.
Thickening processing without irregular deformation such as buckling can be achieved,
The object of the present invention is to provide a method for increasing the thickness of a tube material, which can reduce the amount of increase in thickness toward the inner diameter side, and an apparatus that can be used directly to carry out this method.

[Summary of the invention]

The structure of the method for increasing the thickness of a tube material according to the present invention is such that the portion of the tube material to be thickened is successively locally heated so that the surface layer of the tube material becomes high in temperature and there is a temperature gradient in the inner and outer diameter portions of the tube material. The thickness of the thickened portion is increased by performing swaging processing by applying a compressive force in the axial direction of the tube material while performing high-frequency induction heating so as to give the same.

Moreover, the structure of the pipe material thickening processing apparatus according to the present invention includes a load device that can compress the pipe material in the axial direction, and a load device that is disposed so as to be located on the outer periphery of the pipe material, and a load device that can compress the pipe material in the axial direction. It is equipped with a movable annular heating coil, a high-frequency oscillator that generates a high-frequency current to be supplied to the heating coil, and a frequency controller that can control the frequency of the high-frequency current.

More specifically, the method for increasing the thickness of a tube according to the present invention is as follows.

By combining high frequency induction heating and forced cooling,
By applying a compressive force to the tube material in a state where the tube material is locally heated, the deformation region is limited, thereby making it possible to increase the thickness without irregular deformation. In addition, the penetration depth changes depending on the frequency of the high-frequency current, and when the penetration depth becomes shallow, a temperature gradient occurs in the thickness direction of the heated object, and the high-temperature side (surface layer) of the heated object The magnitude of the frequency of the high-frequency current in the high-frequency induction heating is controlled by actively utilizing the phenomenon that the deformation resistance is small and the deformation resistance is large on the low temperature side, creating a gradient of deformation resistance in the plate thickness direction. By setting the desired temperature gradient in the thickness direction, the distribution ratio of the amount of increased thickness between the inner and outer diameters (= amount of increased thickness on the outer diameter side / amount of increased thickness on the inner diameter side) is controlled, and the inner diameter side The amount of increase in thickness is reduced.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to Examples.

FIG. 2 shows an example of a pipe material thickening processing apparatus used for carrying out a pipe material thickening processing method according to an embodiment of the present invention, and a pipe material to be processed by the same. FIG.

In this FIG. 2, 1 is a tube material to be thickened, 4 is a pressbed provided with a positioning part 4a for positioning one end of the tube material 1, and 3 is a pressbed on its side (left side in FIG. 2). Plate 5a, 5 to which a hydraulic cylinder 6, which will be described later, is attached
Reference numeral b designates a support column that fixes the plate 3 and press bed 4 at positions facing each other with a predetermined distance therebetween, and is capable of receiving the reaction force of the compressive force, which will be described later. Further, the support column 5b also serves as a guide for the axial movement of the transformer 12, which will be described later.

Reference numeral 13 denotes an annular heating coil that is disposed around the outer periphery of the tube material 1 and can heat the tube material 1. It is movable along one side of its inner diameter surface (heating coil 13
On the opposite side to the forward direction indicated by the arrow), there is an injection port 13a for injecting a part of the cooling water 14 for cooling the heating coil toward the pipe material 1 at an angle of 45°.
The holes are distributed in the circumferential direction. Further, a two-color thermometer (not shown) that can detect the temperature of the heating section of the tube material 1 is integrally attached to the heating coil 13. A transmitter (not shown) is provided that emits a signal when the temperature of the controller reaches a preset temperature. 15 is a cooling water pipe that supplies cooling water 14 to the heating coil 13.

10 is a high frequency oscillator that generates a high frequency current;
11 is a frequency controller capable of controlling the frequency of the high-frequency current and equipped with a frequency setting dial (not shown); 12 is a transformer that controls the magnitude of the high-frequency current supplied to the heating coil 13; This transformer 12 is turned on by a signal from the two-color thermometer (not shown), and is turned on by a signal from a limit switch 16, which will be described later.
It has a drive unit equipped with a relay switch (not shown) that turns off and a heating coil movement speed setting dial (not shown), and if the heating coil movement speed setting dial is set to a predetermined speed in advance. ,
When the relay switch is turned on, the pillar 5
The heating coil 13 can be moved at the predetermined speed by moving forward in the direction of the arrow along the axial direction of the tube material 1 while being guided by the arrow b.

6 is a hydraulic cylinder related to the load device, and this hydraulic cylinder 6 is turned ON by a signal from the two-color thermometer (not shown) and turned OFF by a signal from a limit switch 16, which will be described later. It has a relay switch (not shown) and an oil pressure setting dial (not shown).

Reference numeral 16 denotes a limit switch which, when the heating coil 13 finishes heating up to the end of the thickened part, the transformer 12 comes into contact with it and closes, producing a signal.
The signal from the limit switch 16 is sent to the relay switch of the transformer 12, the high-frequency oscillator 10, and the hydraulic cylinder 6, so that the transformer 12 stops, the hydraulic cylinder 6 stops driving, and the high-frequency oscillator 10 stops. , stops the generation of high frequency current.

Next, the operation of the pipe material thickening processing apparatus configured as described above will be explained.

First, the spindle 7 of the hydraulic cylinder 6 and the transformer 12 are moved backward. The tube material 1 to be thickened is passed through the heating coil 13, one end of which is inserted into the positioning part 4a of the press bed 4, and the other end is inserted into the heating coil 13.
The spindle 7 is advanced in the direction of the arrow and fixed with a support jig 8. Heating coil 13 is tube material 1
The transformer 12 is advanced in the direction of the arrow until it reaches one end of the thickened part.

A two-color thermometer (not shown) of the heating coil 13 is set to a predetermined temperature. Frequency controller 11
Set the frequency of the high-frequency current using the frequency setting dial (not shown). do). A heating coil moving speed setting dial (not shown) of the transformer 12 is used to set the moving speed of the heating coil, and a hydraulic pressure setting dial (not shown) of the hydraulic cylinder 6 is used to set the oil pressure of the hydraulic cylinder.

Turn on the high frequency oscillator 10 and turn on the heating coil 1.
At the same time as starting the high-frequency induction heating of the tube material 1 by the cooling water pipe 15, the cooling water 14 is supplied from the cooling water pipe 15 to the heating coil 13.

When the temperature of the heated part of the tube material 1 heated by the heating coil 13 reaches the predetermined temperature, a signal is output from the transmitting part of the two-color thermometer (not shown), and this
A relay switch for the hydraulic cylinder 6 (not shown),
and is received by a relay switch (not shown) of the drive section of the transformer 12. Then, the hydraulic cylinder 6 is turned ON, and the oil supplied from the hydraulic pressure generating device 9 pushes out the spindle 7 with the preset constant hydraulic pressure, whereby the pipe material 1 is compressed to a constant degree in the axial direction. compressed by force. Meanwhile, the relay switch of the transformer 12 is also turned on, and the transformer moves in the direction of the arrow at a preset moving speed, continuing to heat the tube material 1 at the predetermined temperature. The amount of water injected from the injection port 13a of the heating coil 13 is adjusted so that the heating width at this time is about twice the plate thickness or less, thereby narrowing the deformation area of the tube material 1.

When the transformer 12 moves forward in the direction of the arrow and the heating coil 13 finishes heating the other end of the thickened part of the tube material 1, the transformer 12 switches the limit switch 1.
6, the movement of the transformer 12 and the driving of the hydraulic cylinder 6 are stopped, the high frequency oscillator 10 stops generating high frequency current, and the thickening process of the pipe material 1 is completed.

Thereafter, after the tube material 1 has cooled, the supply of cooling water 14 is stopped, and the thickened tube material 1 is taken out.

Next, a specific example will be described.

Pipe material 1 has an outer diameter of 216mmφ, a plate thickness of 8.6mm, and a length of
We will explain the case of increasing the thickness of a 5.5m carbon steel pipe over a length of 500mm at a thickness increase rate of 31%.

The conditions for high-frequency induction heating using the heating coil 13 are a frequency of 9 kHz, an output of 85 Kw, a heating temperature of 850°C, and a moving speed of the heating coil 13 of 1 mm/
min, set oil pressure of hydraulic cylinder 6 to 53.8Kg/cm ²
(The inner diameter of the cylinder is 30 cm, so it can produce a compression force of 38 tons.)

In setting the frequency of the high-frequency current in the above-mentioned high-frequency induction heating, a preliminary experiment as shown in FIG. 3 was conducted.

Figure 3 shows an example of the relationship between the frequency of high-frequency current in high-frequency induction heating and the distribution ratio between the inner and outer diameters of the amount of increased thickness when the moving speed of the heating coil is constant. It is a distribution ratio relationship diagram.

In FIG. 3, reference numeral 17 indicates the relationship between the frequency of the high-frequency current in high-frequency induction heating and the distribution ratio of the inner and outer diameters of the thickness increase when the moving speed of the heating coil 13 is 1 mm/min.

Generally, in high-frequency induction heating, as the frequency increases, the penetration depth of the high-frequency current becomes shallower, the surface layer of the object to be heated is more likely to be heated, and a temperature gradient occurs such that the surface layer becomes higher in temperature.

By utilizing the characteristics of this high-frequency induction heating, when the frequency is increased, the temperature near the outer diameter surface of the tube material 1 increases, and the deformation resistance of that part decreases.
Deformation due to swaging is preferentially performed near the outer diameter surface. Therefore, as is clear from FIG. 3, as the frequency of the high-frequency current increases, the distribution ratio of the inner and outer diameters of the increased thickness increases.

For example, in order to ensure that the amount of increase in thickness on the inner diameter side is within the tolerance range for plate thickness dimensions according to JIS,
The inner/outer diameter distribution ratio of the increased thickness may be about 5. The frequency corresponding to the inner/outer diameter distribution ratio 5 of this increased thickness is
Since it is 9kHz, I set it to 9kHz.

When the above-mentioned conditions were set and the thickness increase processing of the carbon steel pipe was performed using the thickness increase processing apparatus according to FIG. 2, the desired thickness increase rate was 31%. A distribution ratio of 5 was achieved, and thickening could be performed without irregular deformation.

FIG. 4 is a perspective view showing an example of a pipe material whose thickness has been increased by the pipe material thickness increasing processing apparatus according to FIG. 2, and FIG. FIG.

In the figure, 18 is a thickened part of the pipe material 1;
8a is the thickened part on the outer diameter side, and 18b is the thickened part on the inner diameter side.The thickened part 18 has a thickening rate of 31%, has no irregular deformation, and has a small amount of thickened wall on the inner diameter side ( Distribution ratio of inner and outer diameter of increased thickness = 5).

According to the embodiment described above, there are the following effects.

(1) There is no irregular deformation such as wrinkles or buckling, and it is possible to achieve thickening processing that reduces the amount of thickening on the inner diameter side.

(2) By simply setting the frequency of the frequency controller 11 to a predetermined frequency, it is possible to reduce the amount of wall thickness increase toward the inner diameter side. , dies inserted into the pipe), etc., the thickening process is easy, and the structure of the apparatus for carrying out this process is simple.

(3) According to the pipe material thickening processing method of this embodiment, since the pipe material 1 can be thickened at any position, the pipe material can be subjected to secondary processing (for example, bending processing,
burring processing, tube expansion processing, etc.), if this secondary processing part is thickened beforehand,
The apparent decrease in plate thickness due to plastic deformation can be reduced. Therefore, there is no need to use thick-walled pipes, reducing material costs by 10-20%.

In addition, in this embodiment, the heating coil 13
Furthermore, since the injection port 13a for injecting the cooling water 14 is provided, there is an advantage that the heating width can be controlled by adjusting the amount of water injected from this injection port.

Note that even if the injection port is not provided, that is, the injection port is not provided, there is little risk of irregular deformation of the tube material 1 in practical terms.

Further, in this embodiment, the hydraulic cylinder 6 was used as a loading device for the pipe material 1, but even if a mechanical screw press or the like is used instead of the hydraulic cylinder 6, the same result as in this embodiment can be obtained. It is effective.

In addition, in this example, the outer diameter is 216 mmφ, and the plate thickness is
A high frequency current of 9 kHz was used to increase the thickness of an 8.6 mm carbon steel pipe to a thickness increase rate of 31% and a distribution ratio of inner and outer diameters of 5. It varies depending on the dimensions of the pipe material (outside diameter and plate thickness), the rate of increase in wall thickness, the distribution ratio of the increase in wall thickness between the inner and outer diameters, etc., but in short, the surface layer of the pipe material becomes hot and the inner and outer diameters of the pipe material increase. Any material can be used as long as it can provide a temperature gradient to the part.

〔Effect of the invention〕

As described above in detail, the present invention has the following effects.

○B There is no irregular deformation such as wrinkles or buckling, and it is possible to perform thickening processing that reduces the amount of thickening on the inner diameter side.

○B By simply setting the frequency of the high-frequency current in high-frequency induction heating to a predetermined frequency, the distribution ratio of the inner and outer diameters of the amount of increased thickness can be controlled. for example,
It is possible to suppress the amount of increase in thickness toward the inner diameter side without inserting a die or the like.

○ C. It is possible to increase the thickness of any part of the pipe material without irregular deformation, so when performing secondary processing on the pipe material, thick-walled pipes can be used by increasing the thickness of this secondary processing part in advance. There is no need to
Material costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a pipe material whose thickness has been increased by a conventional method for increasing its thickness, and FIG. FIG. 3 is a partial cross-sectional view showing an example of a pipe material thickening processing device and a pipe material subjected to wall thickness processing using the device. FIG. 4 is a diagram showing an example of the relationship between the frequency of the current and the distribution ratio between the inner and outer diameters of the amount of increase in thickness. FIG. 5 is a perspective view showing an example of a pipe material that has been processed to increase its thickness.
FIG. 5 is an enlarged sectional view showing details of the vicinity of the thickened portion of the pipe material shown in FIG. 4; 1... Pipe material, 6... Hydraulic cylinder, 10... High frequency oscillator, 11... Frequency controller, 13... Heating coil, 13a... Injection port, 14... Cooling water,
18... Thickening processing part, 18a... Outer diameter side thickening part,
18b...inner diameter side thickening part.

Claims (1)

[Scope of Claims] 1. The inner and outer diameter distribution ratio of the amount of wall thickness increase is determined in advance based on the temperature gradient determined from the relationship between the frequency of high-frequency induction heating and the wall thickness of the tube material to be thickened, and the wall thickness of the tube material is increased. The thickness of the portion to be thickened is increased by performing swaging processing by compressing and deforming the tube material at a constant speed in the axial direction while sequentially and locally heating the portion to be thickened using high-frequency induction heating at a predetermined frequency. A method for increasing the thickness of pipe material. 2. A load device capable of compressively deforming a tube material in the axial direction at a constant speed; an annular heating coil disposed on the outer periphery of the tube material and movable along the axial direction of the tube material; A high-frequency oscillator that generates a high-frequency current to be supplied to the coil, and a distribution of the increase in wall thickness between the inner and outer diameters, which is determined by a temperature gradient determined in advance from the relationship between the frequency and the wall thickness of the pipe material to be thickened. A pipe material thickening processing device characterized by comprising a frequency controller capable of controlling based on a ratio. 3. Thickening of the tube material according to claim 2, characterized in that the heating coil is provided with an injection port for injecting part of the cooling water for cooling the heating coil toward the tube material. Processing equipment.