CN105908318B

CN105908318B - Godet unit with induction coil arrangement for heating

Info

Publication number: CN105908318B
Application number: CN201610091144.1A
Authority: CN
Inventors: U·巴德尔
Original assignee: RITTER ELEKTRONIK GmbH
Current assignee: RITTER ELEKTRONIK GmbH
Priority date: 2015-02-19
Filing date: 2016-02-18
Publication date: 2020-02-07
Anticipated expiration: 2036-02-18
Also published as: CN105908318A; CH710793A2; CH710793B1; DE102015108635A1

Abstract

The invention relates to a godet unit (1) having a cylindrical, heatable roller sleeve (2) made of ferromagnetic and electrically conductive material, having a thickness (D) and having an outer circumferential surface (21) for heating and guiding at least one thread (14) or a strip (15), the roller sleeve enclosing an inner space (22), a rotatable drive shaft (5) is arranged centrally in the interior, on which the roller sleeve (2) is fastened by means of an outer end face (7), and the godet unit has a stationary induction coil arrangement (3) on the coil carrier (4) between the drive shaft (5) and the roller sleeve (2), wherein the coil former (4) is made of a non-conductive and non-ferromagnetic material, preferably glass, and is arranged concentrically to the drive shaft (5) and the roller shell (2), wherein substantially no ferromagnetic material is present in the interior (22).

Description

Godet unit with induction coil arrangement for heating

Technical Field

The invention relates to a godet unit having a cylindrical roller sleeve that can be heated by means of a stationary induction coil arrangement.

Background

Heated godet rolls are used in the textile industry for heating and guiding at least one thread or a belt. The roll sleeve is typically rotated at a peripheral speed of up to 8000 meters per minute [ m/min ]. Various systems for heating roller sleeves are known in the prior art, wherein heating can be effected from the outside on the one hand, but preferably by means of components located inside the roller sleeve on the other hand. One such arrangement is described in DE 19540905 a1, in which a stationary induction coil located inside the roll shell can induce an electric current in the roll shell, which heats the roll shell. The invention results from this arrangement which also describes how temperature measurements from a rotating sleeve can be transmitted outwardly to a stationary device.

There are many other embodiments for inductively heating the roll shell by means of an induction coil arranged inside the roll shell. Common to all these embodiments is that ferromagnetic materials, preferably in the form of laminated plates or ferrites, have been used to date in order to conduct the magnetic flux of the induction coil as completely as possible in the roller sleeve. This requires a large amount of material and results in a relatively heavy and expensive induction heating structure. However, this has hitherto been regarded as necessary in order to avoid heating of the drive shaft and other components in the godet unit and to achieve as efficient a heating of the roller sleeve as possible.

Disclosure of Invention

The aim of the invention is to design an induction heating structure in the interior of a roller shell in a lighter weight and less costly manner without significantly increasing the losses.

A godet unit according to the following is used to achieve the above object.

The godet unit according to the invention has a cylindrical heatable roller sleeve made of ferromagnetic and electrically conductive material, which has a thickness and an outer circumferential surface for heating and guiding at least one thread or strip and which surrounds an inner space in which a rotatable drive shaft is arranged centrally and to which the roller sleeve is fastened by means of an outer end side, and has a stationary induction coil arrangement on a coil carrier between the drive shaft and the roller sleeve, wherein the coil carrier is made of electrically non-conductive and non-ferromagnetic material and the coil carrier is arranged concentrically with respect to the drive shaft and the roller sleeve, wherein, apart from the possible ferromagnetic drive shaft, substantially no ferromagnetic material is present in the interior space.

The coil arrangement according to the invention is a so-called "coreless" or "coreless" arrangement, i.e. there are no internals which conduct the magnetic field inside the roll shell. Surprisingly, the omission of the magnetic field-conducting insert does not lead to a significant increase in losses, nor does it lead to other components being heated to a greater extent than the roller sleeve. In fact, according to the invention, a coil former made of plastic can be used, whereby the entire induction coil arrangement has a significantly smaller weight than a coil former according to the prior art. However, surprisingly, glass has also proven to be a suitable material. Glass tubes can be produced cost-effectively and have a better heat resistance than most plastic parts, so that glass can be used inside the godet even at very high temperatures. Advantageously, glass types are used which are modified specifically for use at high temperatures, for example from 100 ℃ to 200 ℃ or even 300 ℃. Glass has not hitherto been considered as a material for components in the interior of the godet roll, since the different thermal expansion coefficients of metal and glass are considered disadvantageous by the person skilled in the art. The coil former is in fact fixed or elastically clampable only on one side, so that the coil former can expand in the axial direction independently of the other components. And the coil frame only needs to support the coil, so that the coil does not generate additional load on the glass tube under the condition of high rotating speed because the coil has good balance. In addition, the cost of the substantially cylindrical coil former made of glass is significantly less than the material cost and assembly cost of using laminated silicon steel sheets for transformers. It appears from this that even a very homogeneous induction heating of the roll shell can be achieved without the use of means for conducting the magnetic field. According to the invention, an induction coil arrangement is preferably used, which has at least one coil extending concentrically around the drive shaft, which coil can be connected to an alternating current source having a predefined frequency and/or current intensity.

The basic arrangement of a cylindrical coil and its supply by an ac power source are known in principle from the prior art. Omitting a ferromagnetic coil core, although it results in a slight reduction in inductivity, this can be compensated for by suitably modifying the alternating current supply or by increasing the frequency. The invention therefore requires only minor modifications to the known current supply and control devices.

Losses can be kept particularly small when the induction coil arrangement is spaced apart from the roll shell by an outer annular gap, which is substantially smaller than the inner annular gap, and the induction coil arrangement is spaced apart from the drive shaft by an inner annular gap. Thereby, the magnetic field density inside the coil is relatively small, while the magnetic field outside the coil arrangement is concentrated in the roll mantle. The size of the inner annular gap is preferably at least twice the size of the outer annular gap, in particular more than five times the size of the outer annular gap.

In a preferred embodiment of the invention, the drive shaft has a coating with good electrical conductivity, in particular a coating made of aluminum or copper, at least in the interior of the roller shell.

This can be achieved, for example, by mounting an aluminum tube having a thickness of 0.1-3 mm, which is covered on the drive shaft. Since the drive shaft is usually made of an electrically conductive material, in particular even a ferromagnetic material, the magnetic field also generates an electric current in the drive shaft and heats it inside the coil arrangement. Although this is only to a slight extent due to the size of the inner annular gap, it is not desirable. A coating with good electrical conductivity, which can be realized, for example, by means of an aluminum or copper tube, forms surface eddy currents due to the low electrical resistance, which act counter to the magnetic field which generates such eddy currents and thus act as if it were excluded from the region of the drive shaft. Although this surface may become heated, it is much weaker than would otherwise be the case for the entire drive shaft.

According to the invention, the coil arrangement is designed for its purpose such that an alternating magnetic field is generated by an alternating current flowing in the coil or coils, which alternating magnetic field penetrates into the roll shell and induces a current there, which heats the roll shell.

According to the invention, in principle all known coil arrangements for this purpose can be used without ferromagnetic material in the interior of the roll jacket, but a cylindrical coil or a plurality of cylindrical coils arranged one behind the other are particularly suitable for this purpose.

According to the invention, the sleeve may have an axial length of 100mm to 1500 mm. Alternatively or additionally, the roller shell may have an outer diameter of 100mm to 500 mm. The invention is also suitable here for very long godets with axial lengths of up to 1500mm or even more, owing to the simple structure of the coil former. The coil arrangement is also not restricted in terms of outer diameter, so that the outer diameter can well reach 500mm and above.

As is known in principle from the prior art, the temperature regulation according to the invention can also be achieved by measuring the temperature in the godet roller by means of at least one temperature sensor, wherein the temperature sensor is arranged in or on the roller sleeve and is connected to a control device for controlling the ac power supply of the induction coil arrangement.

It should also be noted that in a preferred embodiment of the invention, the outer end face of the godet roller, which connects the roller sleeve to the drive shaft, is made of a ferromagnetic material. The hub is also advantageously heated. At the same time this prevents stray magnetic fields from appearing outside the godet unit. The outer end side has a thickness similar to the thickness of the sleeve.

Drawings

An embodiment of the invention is described below diagrammatically in accordance with the drawings, but the invention is not limited to this embodiment. The figures show:

figure 1 shows a schematic longitudinal section of a godet unit according to the invention,

figure 2 shows a cross-sectional view taken along the line II-II in figure 1,

figure 3 shows a typical magnetic field profile in the godet unit according to figure 1,

fig. 4 shows typical eddy currents in the godet unit according to the invention according to fig. 2, and

fig. 5 shows a fastening structure of a glass tube as a bobbin.

List of reference numerals:

1 godet unit

2 roller sleeve

3 Induction coil

4 coil rack, glass tube

5 drive shaft

6 clad/aluminium tube

7 outer end side

8 current transmission device

9 AC power supply

10 temperature sensor

11 signal transmission system

12 control device

13 supporting structure

14 bearing

15 filament

16 belts

17 draw bar

18 flange plate

19 trough with silicone lining

20 fastening nut

21 outer peripheral surface of the roll shell

22 inner cavity of roller sleeve

Thickness of D roller sleeve

Thickness of d coating/aluminum tube

R1 internal annular gap

R2 outer annular gap

L axial length of roll sleeve

Outer diameter of A roller sleeve

Induced current in I1 aluminum tubes

Induced current in I2 roll shell

Current in I3 induction coil arrangement

M magnetic field

Detailed Description

FIGS. 1 and 2 show a galette according to the invention in a schematic way in longitudinal and cross-sectional views

Partial structure of a unit 1 with a roller sleeve 2 having a thickness D. The roll shell 2 is connected on the outer end side 7 to a drive shaft 5, which extends concentrically in the interior 22 of the roll shell 2. The drive shaft 5 is surrounded by an aluminum tube 6 at least inside the inner chamber 22, wherein the aluminum tube 6 has a layer thickness d of 0.1 to 3 mm. Also concentrically to the roller sleeve 2, a coil carrier 4, preferably a glass tube, is arranged in the interior 22, which coil carrier supports a cylindrical induction coil arrangement 3, in particular in the form of a continuous cylindrical coil. The induction coil arrangement 3 is spaced from the roll mantle 2 by an outer annular gap R2 and from the drive shaft 5 by an inner annular gap R1. The layer thickness of the coil former 4 and the thickness of the aluminum tube 6 are both taken into account here for the size of the inner annular gap R1. It is important that the coil former 4 is not made of ferromagnetic material and is electrically non-conductive, and that the inner space 22, except for the drive shaft 5 if necessary, usually does not contain ferromagnetic material either. This is thus effectively a coreless or coreless coil arrangement. The power supply of the induction coil 3 is effected by means of a current-carrying device 8, which is supplied by an alternating current source 9. When it is desired, in most cases, to regulate the temperature of the roll mantle 2, it is possible to use regulating systems known from the prior art. For this purpose, at least one temperature sensor 10 can be arranged in the roll shell 2, which temperature sensor is connected via a contactless signal transmission system 11 to a control device 12, which controls the ac power supply 9. Since the signal line 11 has to transmit the measured values from the rotating device, it can extend through the drive shaft and make sliding contact, or a wireless connection can also be used. The entire godet unit 1 is usually fastened to a support structure 13. The drive shaft 5 can be rotatably fastened in suitable bearings 14, while the coil former 4 is fixedly mounted on one side on the support structure 13. The invention is also applicable to godet units 1 having a large axial length L, for example an axial length of 1500mm or more, and to small or large outer diameters a of the order of up to 500mm and above, by reducing the weight of the coil former 4 and the induction coil arrangement 3 and simplifying the structure of the coil former 4 and the induction coil arrangement 3. The sleeve 2 has an outer circumferential surface 21 which is suitable for heating and guiding at least one thread 15 or belt 16. Usually, a plurality of threads are also guided on the roller shell 2 and/or a thread is guided in a winding manner in a plurality of turns.

Fig. 3 and 4 illustrate the magnetic and electrical properties of the godet unit 1 according to the invention. In principle, a typical internal magnetic field and an external magnetic field are formed around the cylindrical induction coil arrangement 3, wherein this magnetic field is concentrated externally in the roller sleeve 2 and is largely removed internally from the drive shaft 5 by the action of the aluminum tube 6. This results in the currents I1 in the aluminium tube 6, I3 in the roller sleeve 2, I3 in the induction coil arrangement 3, which are indicated in fig. 4 by the rings and arrows, of course changing their direction correspondingly with the changing magnetic field. The current I3 flowing in the induction coil 3 generates a circular current I2 flowing in the opposite direction in the roll mantle 2 and a weak current I1 also flowing in the opposite direction in the aluminum tube 4. So that a substantial part of the energy of the magnetic field can be used for heating the roll shell 2.

A preferred solution for fastening the glass tube as coil former 4 is shown in fig. 5, in which the glass tube 4 is fastened between the support structure 13 and a flange plate 18 located axially opposite the support structure 13 by means of tie rods 17. The longitudinal expansion of the glass tube can be compensated for on the one hand by the longitudinal expansion of the tie rods 17 and by the end of the glass tube 4 being inserted into a central seat on the flange plate or into a groove 19 with a heat-resistant silicone lining. This fixing also ensures centring, the silicone compensating for the difference in diameter during thermal expansion. The tie rod 17, which is fixed and tightened by the nut 20, is likewise advantageously made of a material that is electrically and magnetically non-conductive.

The invention is therefore suitable as an alternative to the induction godet heating devices used hitherto, which have magnetic field-conducting inserts located inside the roller sleeve. The coil carriers made of plastic are less expensive and lighter in weight than the previously known arrangements with laminated ferromagnetic plates, so that godet units with a large axial length or a large diameter are particularly suitable for equipping the heating device according to the invention.

Claims

1. A godet unit (1) has a cylindrical heatable roller sleeve (2) made of ferromagnetic and electrically conductive material, the roller sleeve has a thickness (D) and has an outer circumferential surface (21) for heating and guiding at least one thread (14) or belt (15), the roller shell surrounds an inner chamber (22), in which a rotatable drive shaft (5) is arranged in the center, on which the roller shell (2) is fastened by means of an outer end face (7), the godet unit has a stationary induction coil arrangement (3) on a coil carrier (4) between a drive shaft (5) and a roller sleeve (2), wherein the coil support (4) is made of a non-conductive and non-ferromagnetic material and is arranged concentrically to the drive shaft (5) and the roller shell (2), wherein, apart from the drive shaft (5), no ferromagnetic material is present in the interior (22).

2. Godet unit (1) according to claim 1, characterized in that the induction coil arrangement (3) has at least one coil extending concentrically around the drive shaft (5), which coil can be connected to an alternating current source (9) of a predeterminable frequency.

3. Godet unit (1) according to claim 2, characterized in that the coil former (4) is made of glass.

4. Godet unit (1) according to one of claims 1 to 3, characterized in that the induction coil arrangement (3) is spaced from the roller sleeve (2) by an outer annular gap (R2) and from the drive shaft (5) by an inner annular gap (R1), wherein the inner annular gap (R1) is larger than the outer annular gap (R2).

5. Godet unit (1) according to claim 4, characterized in that the size of the inner annular gap is more than twice the size of the outer annular gap.

6. Godet unit (1) according to claim 5, characterized in that the size of the inner annular gap is more than five times larger than the outer annular gap.

7. Godet unit (1) according to one of claims 1 to 3, characterized in that the drive shaft (5) has a coating (6) with good electrical conductivity at least in the inner cavity (22) of the roller shell (2).

8. Godet unit (1) according to claim 7, characterized in that the cover is made of aluminum or copper.

9. Godet unit (1) according to claim 8, characterized in that the coating (6) is an aluminium tube having a thickness (d) of 0.1 to 3 mm.

10. Godet unit (1) according to claim 2 or 3, characterized in that the induction coil arrangement (3) is designed such that an alternating current flowing in the coil or coils generates an alternating magnetic field which enters the roll jacket (2) and induces eddy currents in the roll jacket, which eddy currents heat the roll jacket (2).

11. Godet unit (1) according to one of claims 1 to 3, characterized in that the roller sleeve (2) has an axial length (L) of 100 to 1500 mm.

12. Godet unit (1) according to one of claims 1 to 3, characterized in that the roller sleeve (2) has an outer diameter (A) of 100 to 500 mm.

13. The godet unit (1) according to one of claims 1 to 3, characterized in that at least one temperature sensor (10) is arranged in or on the roller sleeve (2), which temperature sensor is connected to a control device (12) for controlling the alternating current source (9) of the induction coil arrangement (3).

14. Godet unit (1) according to one of claims 1 to 3, characterized in that the outer end side (7) is made of ferromagnetic material and has a thickness equal to the thickness (D) of the roller sleeve (2).