DE1916870A1 - High frequency heating device - Google Patents

Description

High frequency heating device

The invention relates to a high-frequency heating device, in particular a heating device for a non-contact Continuous heating of a moving object. Length, such as a metal wire, an insulated conductor wire, a tube or the like., For the purpose of a continuous Annealing treatment or a heat treatment of the insulating sheath of lead wires.

There are several methods of continuously heating a moving metal wire, such as a bare one Copper wire, a synthetic resin-coated lead wire, an enamel wire or the like., Known. With these well-known In the process, the heating is carried out either by thermal radiation by means of an electrical or an infrared heating device or by heat conduction by means of a liquid or by passing an electric current or by inductive heating. Heating by heat radiation and conduction is unfavorable because the thermal efficiency is very low as other objects as the object to be heated are also heated.

furthermore, the thermal sensitivity is low because the used devices have a large thermal capacity. When the heating is done at great speed must be, but a large-sized heater is required for such purposes. The low thermal see sensitivity makes a rapid change in temperature difficult and thus even heating.

Heating by passing an electric stro-i

909841/0268

BATH ORIGINAL

mes through the object to be heated requires electrodes for the supply of energy and for inductive heating, contact elements are used to form a secondary circuit needed. When a moving object is heated according to the aforementioned methods, there is a risk of Damage from friction or spark discharge that occurs between the object and the electrodes or the contact members can train.

In the wood industry as well as in the production of synthetic fibers and also in the food industry there are dielectric Known heating method. For example, the so-called microwave oven with a hollow resonator for the generation of microwaves has been put to practical use. This method is based on the dielectric losses and is therefore unsuitable for heating a fast moving wire. It is also difficult to use this procedure for heating embedded metallic conductors, e.g. lead wires surrounded by insulation use. '

The invention is based on the object of a high-frequency heating device to create that does not have the disadvantages of the known heating devices.

To solve the problem, a heating device is provided according to a main characteristic of the invention, which from a highly lossy high-frequency transmission line, that consists of a moving element to be heated as an inner conductor and a surrounding element outer conductor is formed, a high frequency power source for feeding the transmission line and a Waveguide arrangement as a non-contact coupling member composed between the energy source μηά the inner conductor.

According to a further feature of the invention, the transmission

~~ ~~ 9 0 9 8 4 1/0268 ~~~

BATH ORIGINAL "

- 3 -
line designed as a coaxial line.

In a further embodiment of the invention are on the transmission line short-circuit elements in the vicinity of the two ends for a contact-free short-circuit of the inner and outer conductor arranged in such a way that the transmission line forms a high frequency resonator.

According to the further invention, the coaxial line can be used to create a loss circle without contact with the inner conductor be connected.

The invention also provides that around the outer conductor of the coaxial line or the coaxial resonator an electric heater is arranged.

Furthermore, according to a further characteristic of the invention the coaxial line or the coaxial resonator can be arranged in a dielectric liquid.

According to the invention, the inner conductor can consist of a bare copper wire, an enamel wire or a wire with consist of a synthetic resin coating.

The high frequency heating device according to the invention is special suitable for continuous heating of a metallic conductor and a dielectric material, that surrounds the conductor. The high-frequency heating device can be used when heating an encased electrical Conductor the heating not only by dielectric heating dec dielectric material, but also by the heating of the conductor by ohmic losses take place at the same time. The generated high frequency energy will on the object to be heated without contact -transferred and absorbed in the object. Another VorrO Part Desueh-J in the fact that only a small amount of energy is lost and "therefore a high efficiency is achieved. The

ÖÖJs A 1/0 2 6 8

BATH

- Zf. -

Dimensions of the heating device are relatively small so that a great thermal sensitivity and thus a fast temperature control is given »

When the heating device is designed as a hollow resonator in Form of a coaxial cable, a ribbon or flat cable, in which the object to be heated is the inner conductor represents, the gate part results from a broadband coupling with the hollow resonator, which is free of spark discharges «

The high-frequency heating device is also used for foaming plastics in the production of electrical ~ Lines with insulation made of foamed synthetic resin are suitable. Likewise, the facility can be used for continuous G-annealing process of metal wires can be used «

Embodiments of the invention are shown in the drawings and are explained in more detail below. Show it:

• ^ ig. 1 shows a first embodiment of a high-frequency heating device,

Fig. 2 is a side view of a lead for transmission the high-frequency energy partially on a coaxial line without heat-conducting connecting elements cut,

Fig. 3 is a side view of another embodiment partially in longitudinal section, >

Figure 4- is a side view of a further embodiment also in longitudinal section,

Fig. 5 is a perspective view of the embodiment according to Fig. 4-,

BATH ORIGINAL

~~ 909841/0268 ~ ""

_ 5 -

Pig. 6 shows a further embodiment of a high-frequency heating device ,

Pig *. 7 a side view of a course ζ final element of it one Heating device,

8a is a diagram of the frequency profile of the short-circuit element,

Fig. 8b is a schematic representation of a measuring device for the measurement of the characteristic shown in Fig. 8a,

9 shows a loss circle arrangement,

10 shows a diagram of the waviness factor as a puncture the frequency of a cavity resonator with and without the loss circuit shown in FIG. 9 and

11 shows the use of a heating device according to the invention tion in the manufacture of an electrical line with an insulation made of foamed synthetic resin.

In the embodiment shown in FIG. 1, the conductor 1 to be heated is a bare one Copper wire, one with a synthetic resin coated electrical Head or an enamel wire or the like which is moved in the direction of the arrow by a device not shown is, A tubular outer conductor 2 is arranged coaxially to the conductor 1, so that both parts are very lossy Form coaxial line 2 '. With the outer conductor 2, a power supply 3 is coupled to the Conductor 1 is not in metallic connection. The supply line 3 is a coaxial waveguide converter with respect to the inner conductor 1 'of the coaxial line 2'. The coupling ratio can be moved by a Short-circuit plate 33 with an adjusting screw

90 * 841/0268

BATH ORIGINAL

1918870

34- a waveguide section 31 is connected, be changed. At a further waveguide section -32 adjustment screws 36 are available. The connector section 32 is provided with a level coupler 4 and a level conductor 5 in. 'In-line.

em /

The calibration conductor 5 is connected to a magnetron head consisting of a magnetron tube 7, a waveguide 6 and a short-circuit bulb 61. The energy supply line 3 »the Eichtkoppler 4-, the Eichtleiter 5 and the waveguide 6 form a waveguide system for the transmission of high-frequency energy from the energy source 7 to the. Coaxial line 2 '. The alignment coupler 4 - is equipped with a detector and a galvanometer (not shown) and is used to monitor the ^{energy fed into the coaxial line 2 1} and the energy reflected from the supply line 3. The energy reflected from the coaxial line is absorbed in the calibration conductor 3 in order to keep the energy source constant «,

The waveguide 6 is equipped with a "sliding short-circuiting plate, which can be actuated by an adjusting screw for the adjustment of the waveguide system to the energy source 7. As a high-frequency energy source 7 ^: a microwave oscillator with high energy _} such as a magnetron, the microwaves with a ! Frequency of 24-50 MHz can be used.

In the aforementioned embodiment, the high-frequency energy generated by the energy source 7 is excited in the waveguide 6 and transmitted ^{through the waveguide system to the coaxial line 2 1.} If the short-circuit plate 33 and the adapter elements 56 of the coaxial line 2 ^! supplied '. Since the coaxial line 2 'is designed as a very lossy transmission line, the supplied high-frequency energy is concentrated in the conductor 1, which in the case of

.909841 / 928?

BAD ORiGiNAC

of an Eupferleiter. Ohmic losses and in the event an insulated conductor is additionally heated up by dielectric losses. Venn also the inner wall of the outer conductor 2 with a suitable lossy material such as ferrite or iron the conductor also absorbs the radiant heat the line in addition to the heat generated by itself.

The microwave energy according to the coaxial TM mode is extremely suitable for concentrating radio frequency energy in the inner conductor and destroying it within the conductor. The TEM mode is also stable against mechanical vibrations of the moving conductor 1.

The heater shown in Fig. 3 is equipped with an electric heater 20, the outer Surrounding conductor 2. The heating device 20 is in a *. Thermal insulation material 21, such as asbestos, embedded and surrounded by a metallic protective tube 22 "

-With such an arrangement, the conductor 1 can not only through ohmic and dielectric losses, but also through Radiant heat of the outer heater 20 can be heated. Such a design of the heating device, in particular if they ran for foam processes in the manufacture of electrical cables with an insulation made of foamed Synthetic resins is used, enables high production speeds while maintaining good quality.

In the exemplary embodiment shown in FIGS. 4 and 5, the coaxial conductor system 2 ^{1 is arranged} in a dielectric liquid 26. In this case, the high-frequency energy not only causes the conductor to be heated

909841/0268

BATH ORIGINAL

through its on.mscn.en- and dielectric losses, but also through the dielectric losses of the liquid 26 _s. For this purpose, the outer conductor 2 is equipped inside with a heat-resistant dielectric tube 23 _r, for example a fused quartz tube _? . which prevents the fluid 26 from draining into the waveguide system 24. The dielectric liquid, 26 must have such a dielectric constant and a dissipation factor that it can be heated to a predetermined temperature by dielectric losses. The liquid used can preferably be water or glycerine. ■

The conductor 1 runs through the opening 43 and 42, through a. Container 25 and finally through openings 42 'and 43'. It is heated within the coaxial conductor 2 ′ by its ohmic vision and dielectric losses and additionally by the liquid 26. The liquid 26 is circulated through a pipeline 41 with the aid of a pump 30, the liquid being supplied through lines 28 ″ and 29 collecting spaces 44 and 44 '. This arrangement can also be used in the manufacture of electrical lines with an insulation made of foamed synthetic resin used _o It also allows high production speeds =,

To the thermal efficiency of the high-frequency heating input- '.-. To improve direction and reduce the losses of high frequency energy, a resonator is formed by short-circuiting the inner and outer conductors at the two ends of the lossy transmission line. Since the conductor 1 must be guided without direct contact with any part of the entire device, contact-free short-circuit elements and contact-free exciter sections are to be provided for such a coaxial resonator. The contact-free short-circuit elements can be formed by utilizing the effect of the short-circuit detuning of a hollow resonator ₉

909841/0288

BATHROOM OHIGiNAL

the one tunable waveguide with a pair of tubes for the passage of the conductor according to FIG. 7. As far as the non-contact excitation is concerned, the coaxial waveguide transducer according to FIG. 2 "can be used at which the movable short-circuit piston not only controls coupling with a cavity, but also adjusting the resonance frequency without changing the length of the coaxial cavity.

A heating device of this type of Re sonator is shown in FIG. In the vicinity of the ends of the coaxial line 2 ¹ , non-contact short-circuit elements 8 and 8 'are arranged. The short-circuit elements 8 and 8 ¹ , which are shown in Fig. 7 in detail, each consist of two waveguide members 81 and 82j which are laterally connected to the outer conductor 2 of the coaxial line, a metal plate terminating the free end of the waveguide member 82 and a movable one Short-circuit plate 8A-, which is connected to an adjusting screw 85. The adjusting screw 85 is mounted on the free end of the waveguide member 81. The contact-free KurζSchlußelemente 8 and 8 'work like a cavity filterο

Fig. 8a shows an example of a short-circuit characteristic of a contact-free short-circuit element 8 or 8 ^! which was determined by the measuring device shown in FIG. 8b. The applied frequency is plotted on the abscissa of the diagram and the output / input level ratio is plotted on the ordinate. In the short-circuit element shown in Fig. 8b, the rectangular waveguide has internal dimensions of 34 x 72.1 mm, while the input and output lines 4-5 and 45 'each consist of a coaxial line with an inner conductor of 16.9 mm and an outer There are conductors with a diameter of 38.8 mm. A high-frequency oscillator 4-6 is connected to the input of the coaxial line and a level meter 47 is connected to the output. The input and output lines 45 ′ and 45 are on the oscillator 46

909341/0268

BATH ORIGINAL

1918870

r 10 -

or the level meter 4-7. As can be seen from the diagram in Fig. 8a results, the course-closing effect of Short-circuit element "of Fig. 8b at frequencies 2.4-56 and 2.4-93 MHz on «The short-circuit frequency can be caused by the moving Short-circuit plate 84- can be changed in the desired manner; it must, of course, be at the frequency of the radiofrequency energy source to match.

In Fig. 6 with the reference numerals 9 and. 9 'each one Monitoring device for energy losses from the coaxial resonator, in which a loop of suitable shape or a sample is inserted is designated.

It is more advantageous to make the factor Q ₁ of the resonator somewhat smaller with regard to a spark discharge and the broadband coupling with the resonator. The reduction of the factor Q can easily be brought about by a load of loss material, such as, for example, polyiron or ferrite, in the cavity or by coupling loss circles to the cavity. The loss circuit used in one embodiment consists of a non-contact coupler 103, a directional guide 105 and a waveguide converter 106 (FIG. 9). The change in the factor Q can be seen from the diagram in FIG. 10, in which the applied frequency is plotted on the abscissa and the input wave ratio of the coaxial resonator is plotted on the ordinate.

In the above description, the formation of a high loss transmission line and a resonator on a coaxial line. One such lossy transmission line or «, a The resonator can of course also consist of a ribbon or flat

line to be formed .. - -

The application of the high frequency heating device / for a Foam process in the manufacture of electrical conductors with an insulation made of foamed synthetic resin

909841 / QI8

- 11 explained below with reference to FIG.

A lead wire 11 unwound from a supply reel 10 is, passes through a winch 12 and a Preheater 13 in a container 14 with a coating material. In the container 14, the lead wire is mixed with a solution of a at high temperature crystalline synthetic resin contained in an organic solvent. The lead wire with the Sheath wM then fed to a wire storage 15, in which the crystalline resin cools down and dries out from the solvent during the coating, so that the transparent envelope takes on a cloudy appearance. This step, which is indispensable for the process, is hereinafter referred to as the clouding process. The lead wire with the cloudy envelope is then fed to a high-temperature foaming device in which the coated wire is foamed.

When the high-frequency heating device according to the invention is used as the foaming device 17, heating takes place the sheathing of the conductor wire not only due to dielectric losses occurring in the sheathing itself, but also from the inside through resistance losses of the lead wire.

Further external heating occurs when the in the heating device shown in Figures 3 or 4 is used, will. The resin-covered conductor wire is finally wound up by means of a winding machine 18.

The following are various examples of resin encased Conductor wires in a heating device of the invention.

If the high-frequency heating devices of FIGS. 1, 3 and the pntspT-BrVhfm, ß -nhS 1 1 contained in the following examples 1, 2 and 3 are used for » ς \ ί & knViR-hha-p ^ nmhiin tsn

909841/0 288

BATH

electrical lines as listed in Table 1 Values.

Example 1:

A heavily lossy coaxial line in the design according to I ¹ Xg. 1 used. The outer conductor of the coaxial line had an inner diameter of 53.5 mm and a length of 6.6 m. A rectangular waveguide with inner dimensions of 34 to 72 »1 mm was used to supply the high-frequency energy to the coaxial line. The high frequency source consisted of a magnetron with a power of 1.2 kW at 2.45 MHz. The lead wire was a copper wire 0.32 mm in diameter. The coating solution consisted of one part of high-density polyethylene (density: 0.94-9? Melt index: 0.32) mixed with two parts by weight of xylene as a solvent. The solution was applied to the copper wire ^{at 130 0} O. Example 2: *

A coaxial line with high losses and an electrical heater according to FIG. 3 were used as the heating device. The outer conductor of the coaxial line had an inner diameter of 53 »5 mm and a length of 3? 3 m °. The electrical heater with an energy of 10 kW was arranged outside the outer conductor of the coaxial line. The other conditions were the same as in the first example.
Example $ :

As a heating device, a coaxial Eesonator, as in Fig. 6 is used. The outer conductor of this re- * sonators had an inner diameter of 53.5 m and a length of 2 m. A rectangular waveguide with internal dimensions of 34 mm χ was used as the short-circuit element 72.1 mm used. Otherwise, the same conditions as in Example 1 were present.

BATH

ORIGINAL

909841/02

conditions

- 13 Table 1.

Establishment according to d. Inventor
Example 1 Example 2 Example 3

Gate direction

better known

design type

Feed rate of the lead wire bes (m / min)

Part of the lagging) ends Solvent immediately after foaming (%)

Degree of foaming (%)

Property of the foamed material L in a cross-sectional plane

250

4-00

350

10 12

- 25 28 - 30 27 - 30

The foamed cells
are average
focused so that
the equivalent dielectric constant is reduced

• Epalted cells in the immediate vicinity of the conduction wire

Mechanical properties the wrapping '

) You know

Luffing on the. line wire

none none

no .

150 -

20 15 -

The foamed cells are near the lead wire little concentrated

frequently

medium strong strong

Well

Well

small amount

weak

As can be seen from the table above has a lead wire with a synthetic resin foamed by the use of a heater according to the invention insulation has the following advantages:

5 1. The insulation is foamed evenly and well cured, so that the proportion of residual solvent is low "

2ο Since the optimum of the foaming conditions can easily be reached

4 1 / Q2S8

BATH ORIGINAL

I 916870

is, results in a substantial improvement of the Degree of foaming.

3. The insulation that is well cured has excellent mechanical properties, especially high elongation availability and high mechanical strength.

4 »Because a well cured thin ring-shaped layer makes good contact with the lead wire, the cells near the conductor will not burst.

5 · The insulation is uniform near the conductor foamed, so that an improvement in the electrical properties is also achieved. In the case of a uniform The degree of foaming is the equivalent dielectric constant of the covering in the vicinity of the conductor smaller than in other places =

6. By using the device according to the invention A high processing speed and a high degree of efficiency are achieved.

Although only the heating of the insulation of an insulated electrical wire has been described, the heater may also be applied for the heating of metal wires without wrapping, for example, wires for a continuous annealing process of bare copper \. Examples of such an annealing process for bare copper wires are given below:.

Example 4t

For the annealing treatment, one was afflicted with high losses Coaxial line according to Fig. 1 used. The outer conductor of the coaxial line had an inner diameter of 53? 5 mm and a length of 3.6 m. As a waveguide for the A rectangular waveguide with internal dimensions of ■ was used to feed the high-frequency energy into the coaxial line

909841 / G268

BATH ORIGINAL

191687Q

1316370

- 15 - -

54 χ 72.1 mm "was used. A magnetron was used as the energy source with an output of 1.2 kW at 2.45 MHz. The hard copper wire to be treated had a diameter of 0.4 mm.

Example ^:

For the annealing treatment, a coaxial resonator according to lig 6 used. The outer conductor of the resonator had an inner diameter of 55.5 mm and a length of 2 m In short, the element was · a rectangular waveguide with internal dimensions of 34 χ 72.1 mm provided. The others Conditions were the same as in Example 4.

The results obtained are shown in the table below 2 summarized.

sample Example 4 2 3 Example ^z " 1 '2 5 Throughput speed
speed (m / min) 1 154 183 300 400 500 medium deh
voltage (%) 1-
100 17.78 5.12 20.5 18.1 8.4 middle train
strength
(kg / mm) 21.2 26.44 55.85 25.7. 25.5 50.0 22.77

The invention can of course also be used in manufacture of enamel wires or for the vulcanization process of rubber or plastic-insulated wires.

Claims

909841/026 8 '

Claims (1)

• - 16 claims MJ high-frequency heating device, characterized by a high-loss high-frequency transmission line, that consists of a moving element to be heated as an inner conductor and one around it The outer conductor consists of a high frequency power source for feeding the transmission line and a Waveguide arrangement as a non-contact coupling element between the energy source and the inner conductor. 2. High-frequency heating device according to claim 1, characterized in that that a coaxial line is provided as the transmission line. 3. High-frequency heating device according to claim 1 or 2, characterized in that on the transmission line in the proximity of the two ends short-circuit elements for a contact-free short-circuit of the inner and outer conductor are arranged such that the transmission line forms a high frequency resonator. 4-. High-frequency heating device according to Claims 1 and 2 and 3, characterized in that the coaxial line a loss circuit is connected without contact with the inner conductor. 5 high-frequency heating device according to claim 2, characterized indicates that the outer conductor of the coaxial line is surrounded by an electrical heating device. 6. high-frequency heating unit according to spoke 2, characterized in that that the coaxial transmission line is arranged in a dielectric liquid. 7 high-frequency heating device according to claim 3 ₅ 909841/0268 indicates that the outer conductor of the coaxial resonator is surrounded by an electric heater. 80 high-frequency heating device according to claim 3, characterized characterized in that the coaxial resonator is arranged in a dielectric liquid. 9. High-frequency heating device according to claims 1 to 3, characterized in that the inner conductor consists of a bare copper wire, an enamel wire or a wire with a synthetic resin coating. 1/0288