EP0845196B2 - Galette for heating a running synthetic thread - Google Patents

Abstract

The object of the invention is a galette for heating a running synthetic thread having a plurality of fixed primary windings and a magnetically conductive galette casing rotatable in relation thereto. The galette casing is coupled to the primary windings via shanks of the primary winding supports, arranged therebetween, over a defined radial gap for generating induced currents. The supports are designed in such a way that their transformer sheets are radially superimposed in the region of the groove base, so that the magnetic flux is screened outwards, especially towards the coil supports.

Description

The invention relates to a godet for heating a running synthetic thread according to the preamble of claim 1.

Such godets are known. In the US 3,508,024 a godet for heating a running yarn is described, which has more than two axially successively arranged stationary primary windings and a magnetically conductive godet, which is rotatably mounted concentrically to the primary windings and which is inductively connected to the primary windings via a narrow radial gap for generating secondary currents is. The carrier of the primary windings is composed of a plurality of layered transformer plates, which are mounted perpendicular to the axis of the bobbin. By means of a respective drive circuit, the primary windings are operated with an AC of adjustable frequency, the primary windings are included in a resonant circuit, which is tuned to the set frequency. Via corresponding circuit breakers in cooperation with associated temperature controllers, the resonant circuit is switched on or off depending on the measured temperature on the godet casing.

A similar galette is in the GB 989,349 described in which a primary winding is mounted on a concentrically arranged in a hollow cylindrical godet casing round carrier. Like in the US 3,508,024 are all flat transformer sheets of the carrier of the primary winding in the axial direction on the bobbin layered. With respect to the inner surface of the godet shell, the laminated iron sheets are arranged to form annular concentric air gaps radial to the godet rotation axis.

Generally occurs in such heated godets, the problem that the loss of magnetic flux to the outside, in particular to the coil support is rather large, since all planar transformer sheets of the carrier of the primary windings are laminated in the axial direction on the bobbin. Also, the magnetic flux is not optimal in the carrier thus constricted because boundary layers are formed by transformer sheets joined axially one behind the other. To overcome these boundary layers, a certain energy is needed, which causes a loss of power. Especially with high-frequency application with, for example, 2 kHz and more, the power loss increases dramatically due to stronger boundary layers.

It is therefore an object of the invention to provide a heatable godet of the type outlined above, which allows optimal magnetic flux in the godet by preventing a stray field within the godet shell, in particular in the region of the groove bottom of the carrier and by reducing the power loss caused by boundary layers.

This object is achieved by a godet with the features of claim 1. Advantageous developments are defined in the dependent claims.

Since the magnetic flux, in particular to the coil carrier, is shielded, it is prevented that a stray field can escape to the outside. Thus, an optimal magnetic flux is also possible, which does not have to overcome boundary layers and effectively shields not heated sections.

The special design and arrangement of the transformer sheets ensure better heating of the godet jacket, because the stray field within the godet is significantly reduced.

Another advantage is that commercial cut cores can be used to accommodate the windings. This simplifies the manufacturing process and reduces costs. The gap formed between adjacent cut cores only leads to a very small stray field, which has no influence on the generated current and thus the temperature in the godet casing.

The surface shape of the groove base, over which the carrier is arranged on the bobbin, simplifies assembly.

Also required for high-frequency application thin transformer sheets can be used up to a thickness of 0.01 mm. Since the penetration depth of the magnetic flux decreases with increasing frequency and the conduction of the magnetic flux, however, takes place exclusively on the surface, such thin sheets are useful in order to minimize the power loss.

Fig. 1

eine Schnittansicht durch eine induktiv beheizte Galette;

Fig. 2

eine vergrößerte Darstellung des Nutgrunds gemäß Bereich A in Fig. 1;

Fig. 3

eine Ausführungsform des Trägers gemäß Bereich B in Fig. 1, der mehrere U-förmig ineinander gestapelte Trafobleche aufweist;

Fig. 4A, 4B und 4C

weitere Beispiele des Schnittbandkerns gemäß Bereich B in Fig. 1 zur Erläuterung des technischen Hintergrundes, der aus separaten Schenkeln und einem separaten Nutgrund besteht;

Fig. 5

eine Schnittansicht durch die Galette gemäß Fig. 1, wobei die Anordnung von mehreren segmentartigen Schnittbandkernen auf dem Umfang des Trägers gezeigt ist;

Fig. 6

eine Schnittansicht durch die Galette gemäß Fig. 1, und Fig. 4A oder 4B oder 4C, wobei ein ringförmiger separater Schenkel 3b dargestellt ist;

Fig. 7

eine Schnittansicht ähnlich Fig. 6, wobei jedoch der dargestellte Schenkel 3b sternförmig ausgebildet ist; und

Fig. 8

eine Teilansicht, wobei die Befestigung des Schnittbandkerns auf dem Träger gezeigt ist.

Further advantages, features and applications of the invention will now be explained in more detail using an exemplary embodiment with reference to the accompanying drawings. Show it:

Fig. 1

a sectional view through an inductively heated galette;

Fig. 2

an enlarged view of the groove bottom according to area A in Fig. 1 ;

Fig. 3

an embodiment of the carrier according to area B in Fig. 1 comprising a plurality of transformer sheets stacked in a U-shape;

Figs. 4A, 4B and 4C

Further examples of the Schnittbandkerns according to area B in Fig. 1 to explain the technical background, consisting of separate Thighs and a separate groove base exists;

Fig. 5

a sectional view through the galette according to Fig. 1 showing the arrangement of a plurality of segmented cut cores on the circumference of the carrier;

Fig. 6

a sectional view through the galette according to Fig. 1 , and Fig. 4A or 4B or 4C showing an annular separate leg 3b;

Fig. 7

a sectional view similar Fig. 6 However, wherein the illustrated leg 3b is formed star-shaped; and

Fig. 8

a partial view, wherein the attachment of the Schnittbandkerns is shown on the carrier.

At an in Fig. 1 shown inductively heated godet a plurality of axially located on a bobbin 5 carrier 3, each with a primary winding 1 are provided. In this case, a godet casing 2 is clamped by means of a cone arrangement 7 on a spindle 9 mounted in two bearings 8. The bearings 8 are supported on a fixed receiving body 11. The godet casing 2 is formed in cross-section substantially U-shaped and has on its end wall 2a a central opening which is bounded by a substantially cylindrical inwardly directed projection 13 which has an inner cone 7 which fits to a cone of the spindle 9. At the free end of the spindle 9 is a thread on which a nut 10 for fixing the godet casing 2 on the spindle 9 can be fastened. From the receiving body 11 extends in the form of a hollow cylinder, a bobbin 5 through the spindle 9 almost to the end wall 2a of the godet shell 2. On the bobbin 5 in the axial direction a plurality of carriers 3 are arranged one behind the other on the circumference of the bobbin 5. The carriers 3 each have a groove base 3a and spaced apart legs 3b, so that a U-shaped annular space is formed, which serves to receive the primary winding 1. Die U-förmige Ringfläche 3a ist in Fig. 1 dargestellt. The legs 3b extend to just before the inner surface of the godet casing 2. Two adjacent legs 3b form with this inner lateral surface in each case a defined radial gap 4 of the leg width corresponding dimension.

Via a corresponding control device (not shown) arranged in the carriers 3 primary windings 1 are separately controllable, so that a substantially constant temperature along the outer surface of the godet casing 2 can be achieved. About the annular gaps 4 between the legs 3b and the inner circumferential surface of the godet casing 2, which is magnetically conductive, the rotating godet casing 2 is magnetically coupled, so that a voltage is induced in the godet casing, which has a current flow result. The current flow in the godet casing along the circumference has, due to the electrical resistance of the godet material, a heating result. By targeted switching on and off the coil voltage thus the temperature can be adjusted in the godet casing. In order to prevent power losses, in particular with high-frequency application of, for example, 2 kHz and above, the transformer plates are arranged in the groove base so that they lie radially one above the other.

In Fig. 2 is a locally enlarged sectional view of the groove bottom 3a shown, in which the transformer sheets are stacked radially in the region of the groove bottom.

In Fig. 3 and Fig. 5 a preferred embodiment is shown, according to which the carriers 3 are formed so that the layered transformer sheets are stacked U-shaped into each other to so-called Schnittbandkernen, ie, the transformer sheets are in the radial direction and not - as is well known - layered in the axial direction. On the circumference of the bobbin 5 several U-shaped Schittbandkerne 3 are arranged segmentally to several. The segment-shaped cut cores 3 arranged on the circumference of the coil carrier in the circumferential direction without spacing thus form a winding carrier for a primary winding. The advantage of using cutting cores 3 is that the magnetic flux towards the outside, in particular also to the coil support 5, is shielded, so that no stray field can escape to the outside. For this purpose, the layered transformer sheets are stacked in a U-shape. This also allows an optimal magnetic flux that does not have to overcome any boundary layers. Trafo sheets, which are arranged one after the other in the axial direction, are caused by high-frequency use with, for example, 2 kHz thicker boundary layers, which lead to a significant increase in resistance. The surface of the groove base 3a, on which the chess band core 3 is arranged on the carrier 5, is either substantially planar or adapted to the surface of the carrier 5 and contacts the surface of the carrier 5. The winding takes place in the circumferential direction. The free ends of the legs 3b of the cut cores are rounded so that a substantially constant radial gap 4 is formed between the godet casing 2 and the free end of the legs 3b. The gap 14 formed between adjacent cut-strip cores 3 leads only to a very small stray field which has no influence on the generated current and thus the temperature in the godet casing 2. In order to minimize the losses caused by the stray field, the kerf cores of the adjacent primary windings can be arranged offset from one another in such a way that axially defined gaps 14 are formed around the width of the legs 3b.

In Fig. 4A an example is shown in which the carrier 3 consists of separate legs 3b and a separate groove base 3a. The groove base 3a of the carrier 3 is a hollow cylinder of a plurality of stacked in the radial direction transformer plates. The legs 3b of the carrier 3 have a plurality of axially stacked annular transformer sheets. The guided between the groove base 3a and the legs 3b radial stray field is very low, which is why no influence on the generated current and thus the temperature in the godet casing 2 is present.

In Fig. 4B shows another example in which the carrier 3 consists of separate legs 3b and a separate groove bottom 3a. The groove base 3a of the carrier 3 is a hollow cylinder of a plurality of stacked in the radial direction transformer plates. The legs 3b of the cutting belt core 3 have a plurality of stacked annular transformer sheets. The axial stray field guided between the groove bottom 3a and the legs 3b is very small, which has no influence on the generated current and thus on the temperature in the godet casing 2.

In Fig. 4C shows another example in which the carrier 3 consists of separate legs 3b and a separate groove bottom 3a. The groove bottom 3a of the cut strip core 3 is a hollow cylinder of a plurality of stacked in the radial direction transformer plates. The legs 3b of the carrier 3 have a plurality of stacked annular transformer sheets. The oblique stray field guided between the groove bottom 3a and the legs 3b is very small, which is why there is no influence on the generated current and thus on the temperature in the godet casing 2.

In Fig. 6 is shown a shape of the leg 3b, both with the arrangement in Fig. 4A as well as with the arrangement in Fig. 4B can be combined. The leg 3b is stacked from a plurality of annular transformer plates. This arrangement is particularly low loss, since the radial gap 4 between the legs 3b and the godet casing 2 without interruptions circumferentially performed substantially constant. The magnetic leakage flux is very low.

In Fig. 7 is shown a different shape of the leg 3b, both with the arrangement in Fig. 4A as well as with the arrangement in Fig. 4B can be combined, in which each annular transformer plate has a star-shaped outer edge. The transformer sheets are stacked axially so that the sternfömigen outer edges are aligned axially one after the other.

In Fig. 8 a possible attachment of the carrier 3 is shown on the bobbin 5, in which, for example, the carrier 3 formed as cut cores are each secured with at least one screw 6 on the bobbin 5 of the godet 2.

The applications of U-shaped layered Trafo sheets in particular the cut cores also have the advantage that the required for high-frequency application thin sheets can be used up to 0.01 mm. Since the penetration depth of the magnetic flux decreases with increasing frequency and the power of the magnetic flux, however, takes place exclusively at the surface. Such thin sheets are required to reduce power losses.

Claims (8)

1. Godet for heating an advancing synthetic filament yam, the godet comprising a plurality of stationary primary windings (1) and with respect thereto a magnetically conductive, rotatably supported godet jacket (2), each of the primary windings (1) being wound on at least one U-shaped carrier (3) consisting of a plurality of transformer sheets, the U-shaped carriers being arranged concentric with godet jacket (2), one following the other on a coil support (5), and the godet jacket (2) being coupled via side walls (3b) of carrier (3) with the primary windings (1) respectively via a defined radial clearance (4) for generating induced currents, wherein the carrier (3) is constructed such that its transformer sheets overlie one another radially in the region of a channel bottom (3a) and are aligned in axial direction of the coil support (5), and that its transformer sheets axially follow one another in the region of side walls (3b) and are aligned in radial direction of the coil support (5), characterized in that the carrier (3) comprises a plurality of transformer sheets stacked into one another in U-shape.
2. Godet as defined in claim 1, characterized in that a plurality of carriers (3) is arranged in the form of segments over the circumference of the coil support (5), so as to receive one of the primary windings (1).
3. Godet as defined in claim 2, characterized in that the channel bottom (3a) of the segment-shaped carriers (3) is substantially flat and contacts the surface of coil carrier (5).
4. Godet as defined in claim 2 or 3, characterized in that the side walls (3b) of the segment-shaped carriers (3) are made arcuate at their free ends, so that a substantially constant radial clearance (4) results between the carrier (3) and the godet jacket (2).
5. Godet as defined in claim 2, characterized in that the outer surface of the channel bottom (3a) above which the carrier (3) is arranged on coil support (5) is adapted to the surface of the coil support (5).
6. Godet as defined in one of claims 2-5, characterized in that the segment-shaped carriers (3) of adjacent primary windings (1) are arranged over the circumference of coil support (5) offset from one another in the axial direction of coil support (5).
7. Godet as defined in one of claims 1-6, characterized in that each of the carriers (3) is mounted on the coil support (5) by means of at least one screw (6).
8. Godet as defined in one of claims 1-7, characterized in that the transformer sheets have a thickness as small as 0.01 mm.

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