JPH0671348A - High-frequency heating coil in heating bending device of metal tube - Google Patents

Abstract

PURPOSE:To enable bending with a small bending radius without causing buckling for a thin wall metal tube and without decreasing compression by forming an inclined surface out of the upper surface of a high-frequency heating coil and narrowing the width of a face opposite to the metal tube. CONSTITUTION:When a high-frequency current is applied from a high-frequency transmitter to the heating coil 9, the metal tube 2 gets induction heating, but the width L1 in vertical direction of the inner end face of the heating coil 9 is narrowly formed and also a clearance tube D1 between the outer peripheral face of the metal tube 2 is narrowly formed. Consequently, the metal tube 2 locally gets induction heating in an extremely short width against the axial direction of the metal tube 2 and is softened. After this heating, a delivery device is operated to send out the metal tube 2 downward. In the one with the upper surface formed into the inclined surface, when cooling water is stuck to the upper surface, it is quickly flowed down and variance in heating is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device in a high frequency heating coil for bending a metal tube with a bending arm while inductively heating the metal tube with the high frequency heating coil.

[0002]

2. Description of the Related Art Conventionally, as a device for bending a metal pipe,
A feeding device for feeding the metal tube in its longitudinal direction, an annular high-frequency heating coil for induction heating a part of the metal tube,
A bending arm that rotates about a position separated from the metal tube by a bending radius at a position substantially the same as the high-frequency heating coil in the feeding direction, and a clamp that is fixed to the bending arm and holds the metal tube are provided. There is a device in which the induction heating part of a metal tube is deformed and bent by the rotation of a bending arm when the tube is fed (for example, Japanese Patent Laid-Open No. 3-230819).

The high frequency heating coil is generally formed in the shape of a rectangular pipe in which the cooling liquid is allowed to flow through the body.

[0004]

By the way, a metal tube is induction-heated by a high-frequency heating coil, this heating part is deformed by rotation of a bending arm, and the deformed part is immediately cooled and bent. In bending, in order to bend a thin metal tube to a small radius, it is necessary to narrow the heating width of the metal tube.

That is, if the heating width of the metal tube in the axial direction is wide, the metal tube will buckle during bending and the flatness will be poor. In the case where the high-frequency heating coil is formed in the shape of a rectangular pipe so that the cooling liquid flows through the inside of the body as in the conventional case, the surface facing the metal tube is necessarily in the axial direction of the metal tube. The heating width of the metal tube becomes wider.

Therefore, a thin-walled metal tube is used as R / D = 1.
(D is the diameter of the metal tube, and R is the bending radius of the metal tube). Therefore, an object of the present invention is to propose a high-frequency heating coil that can be bent at R / D = 1.

[0007]

DISCLOSURE OF THE INVENTION The present invention is to solve the above-mentioned problems, and the first invention is a delivery device (1) for delivering a metal pipe (2) in its longitudinal direction, and the metal pipe. High frequency heating coil for induction heating a part of
A bending arm (5) which rotates about a position separated from the metal pipe by a bending radius at substantially the same position as the high frequency heating coil in the feeding direction, and a clamp (7) which is fixed to the bending arm and holds the metal pipe.
A high-frequency wave, the induction heating section of the metal tube is deformed and bent by the rotation of the bending arm (5) when the metal tube (2) is sent out by the sending-out device (1). Heating coil (9)
Is formed of a thin plate and is fixed to the cooling pipe (11) in a protruding manner.

A second aspect of the invention is a feeding device (1) for feeding the metal pipe (2) in its longitudinal direction, an annular high frequency heating coil (9) for induction heating a part of the metal pipe, and a feeding direction. A bending arm (5) that rotates about a position separated from the metal pipe by a bending radius at substantially the same position as the high-frequency heating coil; and a clamp (7) fixed to the bending arm and gripping the metal pipe,
The induction heating part of the metal tube is deformed and bent by the rotation of the bending arm (5) when the metal tube (2) is sent out by the sending-out device (1). ) Is horizontally projected from the cooling pipe (11), and the upper surface thereof is formed as an inclined surface whose inner end face side is lowered, and the width of the inner end face facing the metal pipe in the axial direction of the metal pipe (2). It is characterized by making it.

[0009]

According to the high frequency heating coil of the present invention, since the width L ₁ of the inner end surface 9a facing the metal tube 2 can be narrowed, the induction heating width of the metal tube can be narrowed.

Further, in the case where the upper surface 9b is formed as an inclined surface whose inner end face direction descends, in the case where cooling water is arranged close to the lower part of the high frequency heating coil, the water boils during cooling. When it blows up to the upper part of the high-frequency heating coil unit and adheres to the upper surface of the high-frequency heating coil unit, the water quickly flows down due to the inclined surface.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on the embodiments shown in the drawings. In FIG. 1, reference numeral 1 denotes a feeder for holding a metal tube 2 to be bent in a vertical posture by a chuck 3 and sending the metal tube 2 downward, which is operated by a hydraulic cylinder or the like.

Reference numeral 4 denotes a guide roller for feeding the metal tube 2 downward in a vertical posture. A plurality of guide rollers (four in the figure) are provided on a machine body (not shown) so as to rotate in contact with the passing metal tube 2. Reference numeral 5 denotes a bending arm that rotates around a rotating shaft 6 provided on a machine body (not shown), and the rotating shaft 6 has a bending radius of the metal pipe 2 at the side of the position where the metal pipe 2 is bent. It is provided away from the heart.

Reference numeral 7 denotes a clamp, which is a lower end portion of the metal pipe 2 in a vertical posture in a state before bending as shown in FIG. 1, that is, a lower end portion of the metal pipe 2 projecting slightly below the bending position B of the metal pipe 2. It is provided integrally with the bending arm 5 so as to grip. The clamp 7 is divided into left and right parts so that the metal pipe 2 can be grasped from both sides, and the metal pipe 2 is lightly held so that the metal pipe 2 can slide.

Reference numeral 8 denotes a stopper, which is moved forward and backward in the horizontal direction in FIG. 1 by a hydraulic cylinder 8a. The clamp 7 of the bending arm 5 is made horizontal as shown in FIG. 1 and the stopper 8 is moved forward. As a result, the stopper 8 is locked to the lower surface of the clamp 7,
The clamp 7 is held in a horizontal posture.

Further, the upper surface of the front portion, which is the locking surface of the stopper 8, is formed as an inclined surface 8b whose front is inclined downward, and the stopper 8 is gradually retracted so that the bending arm 5 is gradually lowered. It is designed to rotate to.

Reference numeral 9 denotes a high frequency heating coil (hereinafter referred to as a heating coil), which is adapted to induction-heat the metal tube 2 by supplying a high frequency current from a high frequency oscillator (not shown).

Reference numeral 10 is a guide roller provided in the heating coil 9. The heating coil 9 and the guide roller 10 will be described in detail with reference to FIGS.

As shown in FIG. 2, the heating coil 9 is formed in an end-shaped annular shape which is partially separated, and its inner diameter is, as shown in FIG. 3, between the outer peripheral surface of the metal tube 2 passing therethrough. Is set so that a slight gap D ₁ is generated. Furthermore, as shown in FIGS. 3 and 6, the vertical cross-sectional shape is such that the vertical width L ₁ of the inner end surface 9a thereof is narrow, and the upper surface 9b facing outward from the inner end thereof has a slope in which the inner end side descends. Is formed on the surface.

The narrower the vertical width of the inner end surface 9a is, and the smaller the gap between the inner end surface 9a and the outer peripheral surface 2 of the metal tube 2 is, the narrower the induction heating width in the axial direction of the metal tube 2 is, and the local area is locally reduced. Since it can perform various heating, the above-mentioned gap D ₁ and the vertical width L of the inner end surface 9a
₁ is narrow.

As shown in FIG. 2, an end-shaped annular cooling pipe 11 separated at the same position as the heating coil 9 is fixedly provided on the outer peripheral portion of the upper surface of the heating coil 9. A holding plate 12 made of an insulating material is fixed to the outer periphery of the cooling pipe 11 by a connecting member 13.

The heating coil is, as shown in FIG.
It may be formed by projecting a thin copper plate from the cooling pipe 11. By using such a thin plate, the vertical width L ₁ of the inner end surface 9a can be narrowed.

The holding plate 12 is slidably mounted and held on a pedestal 14 fixed to the machine body so that it can be freely started in the front-rear direction and the left-right direction. As shown in FIG. 5, the guide roller 10 is rotatably supported by a support arm 10a fixed to the upper surface of the holding plate 12 of the heating coil 9, and a part of the peripheral surface of the guide roller 10 is a metal tube. It comes into contact with the outer peripheral surface of No. 2.

The guide rollers 10 are installed at three equal intervals in the circumferential direction of the metal tube 2, and guide the metal tube 2 so that the axis X thereof coincides with the center of the annular heating coil 9. keeping.

As a result, a small gap D ₁ between the inner end surface 9a of the heating coil 9 and the outer peripheral surface of the metal tube 2 is uniformly maintained over the entire circumference. Referring again to FIG. 1, reference numeral 15 denotes a pan for water or a cooling liquid (hereinafter referred to as water), which is the heating coil 9
It is horizontally arranged in the vicinity of the lower part of and is fixed to an airframe (not shown). The central portion of the tray 15 is shown in FIGS.
As shown in FIG. 5, a water flow hole 15a is formed, and the water flow hole 15a is formed.
Is the center X of the metal tube 2 penetrating the water flow hole 15a.
And a gap D ₂ between the inner diameter of the water flow hole 15a and the outer diameter of the metal tube 2 is set so as to hit the outer peripheral surface of the metal tube 2 when water falls.

Reference numeral 16 is a water supply pipe for supplying water onto the tray 15. The metal pipe 2 to be bent may be a single pipe, or may be a three-layer structure pipe as shown in FIGS. 12 and 13.

The three-layer structure pipe shown in FIG. 12 is a heat insulating member made of a metal inner pipe 16 having a bellows-shaped bellows portion 16a to be bent and a ceramic wool wound around the outer periphery of the inner pipe 16. Material (or sound insulation material) 17 and the heat insulating material 1
7, and an outer tube 18 made of metal provided on the outer circumference. Further, one ends 19 of the inner and outer pipes 16 and 18 are seam-welded to each other, and the other end 20 welds and fixes a wire net ring 21 to the inner pipe 16, and contracts the outer pipe 18 to the outer periphery thereof to make soft contact. I am doing it.

The bellows portion 16a is formed in a wavy shape in the axial direction of the inner pipe 16, and the peaks and valleys are formed over the entire circumference. The three-layer structure pipe shown in FIG. 13 is formed by forming the bellows portion 16a only on the bending direction side of the inner pipe 16, and forms the peaks and valleys of the bellows portion 16a as shown in FIG. The center O'of the circle is eccentric downward from the axis O of the inner pipe 16. Other structures are similar to those of the three-layer structure pipe of FIG.

Next, the bending method will be described.
The pipe bent by the effect of the induction heating of the heating coil 9 is the outer pipe 18 in the above-mentioned three-layer structure pipe, which is the same as bending a single metal pipe.
A method of bending the metal tube 2 including the tube 8 and the single tube will be described.

First, as shown in FIG. 1, the bending arm 5 is placed in a posture in which the clamp 7 is horizontal, and the stopper 8 is locked to the lower surface of the clamp 7 to hold the clamp 7 in the horizontal posture. To do.

Further, the metal tube 2 is supported by a guide roller 4 in a vertical posture so as to be movable downward, the upper end portion of the metal tube 2 is held by the chuck 3 of the feeding device 1, and the lower end portion of the metal tube 2 is
It is inserted between a plurality of guide rollers 10 and the heating coil 9, and the lower end is fitted into the clamp 7 of the bending arm 5 so that the metal tube 2 is slidably and lightly held.

Further, the required amount of water W is continuously supplied onto the pan 15.
Supply to. Next, from the high frequency oscillator to the heating coil 9,
Energize high frequency current. By this energization, the metal tube 2 is guided
Although it is heated, the inner end surface 9a of the heating coil 9 is
Width L ₁Is formed in a narrow shape and is a gap with the outer peripheral surface of the metal tube 2.
D₁The metal tube 2 is locally
Specifically, that is, extremely short in the axial direction of the metal tube 2.
It is induction-heated and softened in the width.

After this heating, the feeding device 1 is operated to feed the metal tube 2 downward. At the initial stage of this delivery, the stopper 8 is still in the engaged state, and the bending arm 5 does not rotate. Therefore, the lower end of the metal tube 2 is
It slides in the clamp 7 from the position B in FIG. 1 and moves slightly downward to the position C in FIG. During this downward movement, the metal coil 2 is induction-heated by the heating coil 9, and is heated and fed until the start of bending thereafter.

A predetermined amount, for example, several tens of millimeters of metal tube 2
The stopper 8 is gradually moved in the unwinding direction from the time point when is moved downward. By this movement of the stopper 8 in the unwinding direction, the bending arm 7 can be rotated downward by the inclined surface 8a thereof, and by the downward movement of the metal tube 2 by the feeding device 1,
The venting arm 7 gradually rotates clockwise in the drawing. Due to this rotation, a bending moment acts on the metal tube 2, and the bending moment is concentrated on the heating portion where the deformation resistance is the lowest due to induction heating, and the heating portion is bent and deformed.

At this time, since the metal tube 2 is heated and fed to the bending start point as described above, no defect such as a bump or an internal sink mark is generated at the bending start point of the metal tube 2. That is, when the bending of the metal tube 2 is started at the same time as the heating of the metal tube 2, the heating range in the axial direction of the metal tube 2 is sharply bent by the bending start moment in a narrow state, so that as shown in FIG. A hump 22 due to buckling is generated on the inside of the bending start point D in FIG.
Occurs. On the other hand, when the heating feed is performed by the time when the bending is started as described above, when the bending is started, as shown in FIG.
As shown in FIG. 1, since the part E before the bending start point D is heated for several tens of millimeters, the expansion and contraction action due to the bending of the metal tube 2 is dispersed in the heating part of a long distance. Therefore, as shown in FIG. 11, a bent tube having no defective portion such as a bump or a sink mark at the bending start point D can be formed.

Next, when the stopper 8 further moves in the unwinding direction and is disengaged from the clamp 7, the bending arm 5 is brought into a freely rotating state, and the bending arm 5 moves downward as the feeding device 1 moves downward. While holding the lower end of the, rotate clockwise in the figure.

By the downward movement of the metal tube 2, the induction heating section by the heating coil 9 also moves, and the bending moment by the bending arm 5 is applied to the metal tube 2, so that the metal tube 2 has the lowest deformation resistance. The heating section is bent while being bent, and is bent as shown in FIG.

Further, the water W supplied onto the pan 15 hits the entire peripheral surface of the metal tube 2 from the water flow hole 15a and flows down. At the time of this bending, the induction heating part by the heating coil has a narrow width, and the pan 15 is provided close to the heating coil 9, and the heating part is cooled immediately after the heating so that the deformation resistance is reduced. By returning to the strength of, the deformation of only the narrow heating part will be continuously performed, even if the thin metal tube, buckling does not occur in the bent part,
In addition, flatness due to bending is suppressed, and a curved tube with good roundness can be obtained. Furthermore, the structure after deformation is also stable.

SUS430MT was used for the metal tube 2, its plate thickness was 1.5 mm, its outer diameter D was 60.5 mm, and its bending R was 60.5 mm (R / D = 1).
The vertical width L ₁ of the inner end surface 9a of the above is set to 1.0 mm, the gap D ₁ between the inner end surface 9a and the outer peripheral surface of the metal tube 2 is set to 1.25 mm, and the metal tube 2 is induction heated to about 800 to 900 ° C. When the metal tube was bent, the buckling did not occur in the metal tube, and the flatness was calculated according to the following equation (1), and it was about 1 to 2%.

Flatness = (A−B) / D × 100 (1) Here, A and B are the maximum outer diameter and the minimum outer diameter of the metal tube 2, as shown in FIG.

Therefore, according to the present embodiment, a thin metal tube is used without buckling and the flatness ratio is about 1 to 2%.
In the range of, bending can be performed with a small bending radius of R / D = 1.

Further, when the water falls from the water flow hole 15a, the water hits the outer surface of the heated metal tube 2 and boils. However, since the water continuously falls downward due to gravity, it hardly blows up. Therefore, it is possible to suppress the occurrence of heating imbalance due to the water blowing up to the heating coil 9 and cooling the heating portion of the metal tube 2.

Therefore, heating is constant over the entire circumference of the metal tube 2, and stable bending is possible. Further, in the case where the upper surface 9b of the heating coil 9 is inclined as shown in FIG. 6, when the boiling water collects on the upper surface 9b, it flows down by the inclined surface and is discharged from the water flow hole 15a.

Next, the case of bending the three-layer structure pipe shown in FIG. 12 will be described. When the outer pipe 18 in the portion where the bellows portion 16a of the inner pipe 16 is located is heated and bent as described above, the bending moment acts on the inner pipe 16 due to the rotation of the bending arm 5. At this time, the rigidity of the bellows portion 16 of the inner pipe 16 is significantly lower than that of the straight pipe state, so that the inner side A, which is the bending center side of the bellows portion 16a, easily contracts and the outer side B, as shown in FIG. Easily extends, and the inner tube 16 easily bends following the bending of the outer tube 18.

Therefore, even if the heat insulating material 17, which is a soft material, is interposed between the inner and outer pipes 16 and 18, the inner pipe 16 is bent as a cold work, and has a flat bent shape without flattening.

Also, when a three-layer structure pipe as shown in FIG. 13 is bent by heating, it bends as shown in FIG.
As in the case of the three-layer structure pipe shown in FIG. 12, it has a clean bent shape. Further, when the metal pipe 2 (also for a three-layer structure pipe) laterally shakes during the heating bending process, each guide roller 10 in contact with the metal pipe 2 maintains the contact state and the metal pipe 2 Follow 2 and move the same amount in the same direction. Therefore, the heating coil 9 integrally provided with the guide roller 10 also moves, and the inner end surface 9a of the heating coil 9 is also moved.
The gap D ₁ between the metal pipe 2 and the outer peripheral surface of the metal pipe 2 does not change even if the metal pipe 2 shakes laterally, and is held uniformly over the entire circumference.

[0046]

As described above, according to the present invention, since the induction heating width of the metal tube can be extremely narrowed, it is possible to reduce the flatness of the thin metal tube without causing buckling. Instead, it can be bent with a small bending radius.

In addition, in the case where the upper surface is formed into an inclined surface, when the cooling water adheres to the upper surface, the cooling water can be swiftly drained to prevent uneven heating.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view showing an embodiment of the present invention.

FIG. 2 is a plan view of the heating unit.

3 is a cross-sectional view taken along the line AA in FIG.

FIG. 4 is a sectional view taken along line BB in FIG.

5 is a cross-sectional view taken along the line CC of FIG.

FIG. 6 is an enlarged side sectional view of a high frequency heating coil.

FIG. 7 is a plan view of a saucer for water.

8 is a side view with a partial cross section showing a state where the metal pipe is slightly lowered from the state of FIG.

9 is a partial cross-sectional side view showing a state in which the metal pipe is sent out from the state of FIG. 8 and bent.

FIG. 10 is a side sectional view showing a bent state of a metal tube by a conventional bending process.

FIG. 11 is a side sectional view showing a bent state of a metal pipe bent according to the present invention.

12A and 12B show a three-layer structure pipe to be bent according to the present invention, where FIG. 12A is a side sectional view and FIG. 12B is a front sectional view.

FIG. 13 is a view showing another three-layer structure pipe,
(A) is a side sectional view, (b) is a front sectional view.

FIG. 14 is a side sectional view showing a bent state of the three-layer structure pipe shown in FIG.

15 is a side sectional view showing a bent state of the three-layer structure pipe shown in FIG.

FIG. 16 is a diagram for explaining flatness.

FIG. 17 is a side sectional view showing another example of the high frequency heating coil.

[Explanation of symbols]

 1 Feeding Device 2 Metal Tube 5 Bending Arm 7 Clamp 9 High Frequency Heating Coil 9a Inner End Surface 9b Upper Surface 11 Cooling Pipe

Claims (2)

[Claims] 1. A feeding device for feeding a metal pipe in its longitudinal direction, an annular high-frequency heating coil for inductively heating a part of the metal pipe, and a bending radius from the metal pipe at substantially the same position as the high-frequency heating coil in the feeding direction. It is equipped with a bending arm that rotates around a position separated by a distance, and a clamp that is fixed to the bending arm and holds the metal pipe.The metal pipe is fed by the feeding device, and the metal pipe is guided by the rotation of the bending arm. A high frequency heating coil in a heating and bending apparatus for a metal tube, characterized in that the heating part is deformed and bent, wherein the high frequency heating coil is formed of a thin plate and is fixed to a cooling pipe in a protruding manner. 2. A feeding device for feeding a metal tube in its longitudinal direction, an annular high-frequency heating coil for inductively heating a part of the metal tube, and a bending radius from the metal tube at substantially the same position as the high-frequency heating coil in the feeding direction. It is equipped with a bending arm that rotates around a position separated by a distance, and a clamp that is fixed to the bending arm and holds the metal pipe.The metal pipe is fed by the feeding device, and the metal pipe is guided by the rotation of the bending arm. In the one in which the heating part is deformed and bent, the high-frequency heating coil is arranged so as to horizontally project from the cooling pipe, and the upper surface thereof is formed into an inclined surface whose inner end face side is lowered to form a metal pipe. A heating and bending apparatus for metal pipes, characterized in that the widths of the inner pipes facing each other in the axial direction are narrowed. Kicking high-frequency heating coil.