DE2329113A1 - Tube bending using induction heating coils - with two yokes to control heat input at the inside and the outside of the bend - Google Patents

Abstract

The parent patent describes the hot-bending of tubes, where the inside of the bend is heated to the bending temp., but the remainder of the periphery (which will form the outside of the bend) is kept at a lower temp. Induction coils are used to heat the tubes, with a yoke being provided at the inside of the bend for concn. of heat at this point. In the present invention, a yoke is also used adjacent to that part of the tube which will form the outside of the bend, but in this case to direct the heat away from the tube, i.e. two yokes with opposite functions are now employed. This modification applies esp. to the induction coil used on the bending line, the object being to obtain better temp. distribution. Laminated keepers are used in conjunction with the yokes employed on the outside of the bend, the distance between the yokes and the keepers being adjustable, i.e. the heat-input can be regulated.

Description

Λ

May 7, 1973 Tpat / 1681 / Mü / Ob

Device for the production of bends from tubes or hollow bodies using the hot bending process (additional registration to P 22 20 Q10. ¹ ))

The invention relates to a device for producing arcs from tubes or hollow bodies in the hot bending process, in which part of the circumference of the pipe to be bent to the deformation temperature of the pipe material is heated, while the remaining part of the pipe circumference, which will form the future outer bend is kept at a lower temperature and using inductors that are on the part that will be the future Inner arch is opposite, are surrounded by yoke plates, according to patent (patent application P 22 20 910.5).

This method can be used to create pipe bends with a small radius of curvature and produce a smooth course of the pipe wall. In the procedure after the main patent application, the comparative Lower temperature on the outer arc is achieved by placing the inductors only on the inner arc of the field-reinforcing Yoke plates are surrounded. In addition, the inductors on the outer arc can be at a greater distance from be arranged on the pipe surface than on the inner bend. These measures bring good results in and of themselves. It can be however, not always avoid that the pipe surface is even with a relatively large distance between the inductors and the pipe surface still too hot on the outer arch. This is particularly true when for the arrangement of the inductors on the Bending machine only has a limited space available. The invention is therefore based on the object of the method according to of the main patent application to such an extent that the temperature distribution, which is to be set unevenly over the circumference of the pipe surface, can be precisely maintained.

409881/0588

This is done according to the invention in that the inductors also on the part that is opposite the future outer arc, are surrounded by yoke plates and that the inductor receiving opening of these yoke plates from the pipe surface is turned away. If several inductors are used, only the inductor located at the bending point is preferred equipped with such yoke plates.

The yoke plates arranged according to the invention shield the magnetic field of the inductors from the pipe surface in the area of the outer bpgen. The workpiece can no longer be exposed to the magnetic field influence and thus no longer heat the pipe on this part. The main part of the heat is therefore transferred to the pipe fed on the later inner curve. The inductors for amplifying the inductive power are there on the pipe facing away from the side with yoke brackets. With this arrangement, the pipe can be especially with limited space Apply the heat precisely to the bending machine.

The magnetic field of the inductors on the outer arch penetrates the room. A conductor brought near would be heated It is therefore advisable to shield this magnetic field. According to a further feature of the invention it is proposed that that the inductors face packets of mutually insulated metal sheets on the outer arch, which in the radial direction are adjustable. If these packets are brought closer to the concentrated field of the yoke plates, a throttle vortex arises in the inductor. effect that regulates the current circuit and even interrupts it when the inductor is fully approached. By the arrangement of the packages Not only does this avoid a certain loss of energy, it also enables the energy supply to be regulated.

In a further expedient embodiment of the invention, such packages can also be used when several inductors are used to regulate the energy supply to these inductors and

409881/0588

to be used to control the heat input into the pipe. For this purpose, it is proposed that the power supply lines to the inductors be surrounded by packets of mutually insulated metal sheets are adjustable in the radial direction.

According to a further feature of the invention, the inductors are simultaneous or independent of one another in the longitudinal direction of the pipe displaceable This arrangement has the advantage that the heating is carried out by the inductors when the tube is at a standstill can be. Here, the bending point can be fixed more precisely than when the pipe is through the stationary inductors would be passed through.

The invention will be explained in more detail using the following exemplary embodiment and the designation «

Figure 1 shows the inductive heating device,

Figure 2 gives the cross section through an inductor a device according to the invention again,

FIG. 3 shows the section III-III according to FIG. 2, and Figure 4 shows the section III-III according to Figure 2 »

1 with the pipe is referred to, which is to be bent in the bending machine to a pipe bend. From the bending machine only the essential elements are shown, namely the clamping 2 connected to the stationary machine part and the clamping element 4 connected to the swivel arm 3. The bending axis is indicated by the line 5.

The tube 1 is heated before bending. An inductive one is used for this Heating device, which in the present case consists of four inductors 6 and 7. A nozzle ring is used to cool the pipe β provided by the air or water on the hot

• The pipe surface is blown.

409881/0588

In detail, internally cooled with water ring in an From surrounds the tube 1 and the stand is provided with power supply lines 9, the inductor 6 or 7 aus.einem hollow. The inductor 6 or 7 is illustrated of yoke plates 10 horseshoe-shaped to summarizes · As shown in detail in Figure 2 on the right and in Figure 3, the yoke plates 10 on the side of the tube 1 that later comes to lie in the inner sheet, arranged so that its opening and thus the inductor faces the pipe surface. In this way, the effect of the magnetic field is concentrated on a limited area of the pipe wall and this is preferably warmed up here »

Yoke plates 11 are also provided on the opposite sides of the inductor, that is to say on the side of the pipe wall which later comes to lie in the outer bend. However, these Joohbleche 11 left of Figure 2 side, and Figure 4 is mounted so that the inductor 6-receiving opening of the yoke plates 11 facing away from the pipe surface · On the ee way, the magnetic field from the pipe 1 shielded and the tube 1 at this point less strong.aufgewännt · For manufacturing reasons, we.d the Jochbleohe 11 just as long as the Joohbleohe 10 so that the yoke 10 and 11 surround the inductor 6 over an equally large part of its circumference.

When using multiple inductors 6 and 7, all in such a way be formed as shown in Figure 2 ·· In any case, must be of at the bending point (line 5) provided inductor 6 on both sides in the manner described above with yoke plates 10 and 11 to be equipped

On the side of the tube 1, which will form the later outer bend, lie ^ n the inductor 6 on the part of its circumference, which with the Joohblechen 11 is equipped, packs of mutually insulated metal sheets opposite these packets 12 are in the radial direction

409881/0588

device can be moved. On the one hand, these packets 12 prevent the magnetic field to penetrate the rear space, on the other hand they generate a choke effect in the inductor 6, which the Current flow regulated and completely suppressed when the packets 12 approach the inductor 6 completely.

Such packages of mutually insulated metal sheets are also used as chokes 13 around the power supply lines 9 of the inductors 7 arranged. These throttles 13 are radially displaceable. They can be used to control the power to be applied and thus the heating process.

The inductor 6 and the inductors working as preheating inductors 7 can be arranged displaceably in the longitudinal direction of the pipe together with the nozzle ring 8. In this way you can fix the bending point more precisely than when the tube 1 is passed through the inductors before bending. The heating of the Tube 1 with the help of the movable inductors 6 and 7 is done in the following way. All inductors 6 and 7 are in The direction of the pipe feed is moved beyond the later bending point (line 5) and switched on at the same time. Is between the inductor 6 and the inductor 7 adjacent to it, the temperature permissible for the outside of the arc approximately reached (with steel around 750 ° 0), this is how the preheating inductors move 7 against the feed at the feed rate. All inductors 6 and 7 have their predetermined distance from one another reached, they move with the inductor 6 to be placed at the later bending point (line 5) the nozzle ring 8 by a distance dependent on the wall thickness into the end position and the bending process begins. These This procedure is particularly applicable to materials that have poor electrical and thermal conductivity and / or have a low Curie point that is, a low permeability. The austenitic materials belong to these materials Steels,

409881/0588

Claims (1)

PATENT CLAIMS 1 · Device for the production of bends from tubes or hollow bodies proceed in hot bending, in which part of the scope of the pipe to be bent to the hot deformation of the pipe material is heated, while the remaining part of the pipe circumference, which will form the future outer bend, is at a lower level Temperature is maintained using inductors on the part facing the future inner arc, are surrounded by yoke plates, according to patent (patent application P 22 20 910.5) »characterized in that the inductors (6, 7) also on the Part that is opposite the future outer arch, surrounded by Jochbleohen (11), and that the inductor (6, 7) receiving opening of this Jochbleohe (11) of the Surface of the tube (1) is facing away. 2 door direction according to claim 1, characterized in that that only the inductor (6) lying at the bending point (5) on the opposite of the future outer bend The side is provided with the Joohbleohen (11) 3 · Device according to claims 1 and 2, characterized in that the length of the outer bow opposite yoke sheets (11) is equal to the length of the yoke sheets (10) opposite the inner bend * 4 · Device according to claims 1 to 3 »thereby g e k e η η indicates that the inductors (6, 7) on the outer bend packets (12) isolated from each other Opposite sheets that are adjustable in the radial direction. 409881/0588 5 · Device according to Claims 1 to 4, characterized in that the power supply lines (9) are closed
the inductors (7) are surrounded by chokes (15) made of mutually insulated metal sheets, which are adjustable in the radial direction. β Device according to claims 1 to 5> characterized) that the inductors (6, 7) in
The longitudinal direction of the tube (1) are displaceable. 7. Apparatus according to claim 6, characterized in that that the inductors (6, 7) are displaceable at the same time. 8. Apparatus according to claim 6, characterized in that the inductors (6, 7) are independent of one another
are movable. 409881/0588 Blank page