DE2408738B2 - METHOD AND DEVICE FOR PRESSING AND CURING AN INSULATED COIL - Google Patents

Description

Temperature is heated.

3. The method according to claim 2, characterized in that 20

indicates that you can get electric current through

lets the coil flow.

4. The method according to claim 1, characterized in that the sand prior to its filling a device for pressing and curing eini in the container to a temperature above 25 from a conductor or conductor bundle and a paint -Curing temperature of the existing coil for the insulating layer impregnated,
used paint is preheated. To improve the insulation properties of an isolated

5. The method according to any one of claims Ibis 4, to improve the coil, provides the usual practice, characterized in that the insulating layer to impregnate an insulating layer of the insulated coil with paint odei prior to the arrangement of the coil in the container with 30 other impregnation materials,
is wrapped in a release film. The layer impregnated with lacquer is applied

6. The method according to any one of claims 1 to 5, using z. B. a catalyst or hardener odei characterized in that it is cured on the in by means of heating. However, zui arise Container to cover the curing time it contains air bubbles in the paint or in the dei Coil-filled sand a vibration act 35 insulating layer as a result of air or moisture that leaves. introduced therein in the course of the application of the lacquer

7. The method according to any one of claims 1 to 6, or as a result of evaporation of the hardness thereby characterized in that one pressure on the means. If the insulated coil with an air-top The bias content of the sand filled into the container has an effect in the insulating layer or in the paint leaves. 40 is hardened, a glow discharge occurs in the

8. The method according to claim 1, characterized in that the insulating layer is characterized by that one noticeably deteriorate after filling the shafts.

Sand in the container a vacuum in the container In addition, paint or the insulating layer is generated, hardened if there are air bubbles in it, se

9. The method according to claim 7, characterized in that there is no dimensional accuracy of the isolated indicates that pressurized gas is allowed to act on the coil and the electrical and mechavon Used pressure on the sand. niche properties in relation to a given

10. The method according to claim 9, thereby impairing the thickness of the insulating layer, indicates that the compressed gas is an inert gas. In order to avoid these disadvantages, have hitherto is used. 50 use the following methods for pressure forming a

11. Device for carrying out the insulated coil into or onto which the paint is switched on or off. Fahrens according to any one of claims 1 to 10, is applied, applied.

characterized by (1) A varnished or varnished one

a) a container (, B. 25), in the sand- ^{lined column is} in a metallic form with can be filled with ⁵⁵ dimensions according to a certain shape.

b) a valve (z. B. 28) for draining the device of the insulated coil placed around the insulated one Sand from the container and coil to shape as well as in this given shape

c) means (z. B. 42) for heating the insulating lacquer ^{of the} Isoherschicht or in the air bubbles contained the insulated coil layer in the sand in loading ^du £ ^h compression expel (CH-PS 2 87 691). halter ^6o According to a modification of the method (1)

the lacquer-treated insulated coil and the die

12. The device according to claim 11, marked at the latest at the beginning of the pressing process to almost characterized by a coil setting device (cage heated to the temperature required for hardening, 24) for receiving a plurality of spools (20). for which the coil is preferably powered by electric current

13. The device according to claim 11, characterized in that 65 is flowed through (GB-PS 9 67 235).
characterized in that a pair of containers (25, good insulation 26) is provided according to this method and that the valve (28) for properties of the insulated coil and also a discharge of sand from a first container achieve accuracy in shape and dimensions ,

as far as the linear parts of the coil are concerned. However, difficulties arise in molding Parts with complicated outlines, such as B. the winding head parts of a diamond coil and also with of making a metallic mold with such a complicated configuration, and it is It is not possible to develop the same pressure everywhere with a metallic mold. aside from that the use of a metal mold is not suitable for mass production.

(2) The lacquer-treated insulated coil is immersed in the hydraulic fluid arranged in a container, around a molding under pressure of about 7 at and the compression of contained therein Getting exposed to air bubbles. In the case of using a thermosetting varnish, the Hydraulic fluid also used as a heating medium (DT-PS 914 867).

In this process, the coil to be formed is used to prevent the pressure fluid from penetrating into the insulating layer to prevent being completely wrapped with a high airtightness film, it is large-scale equipment is required, and the use of the liquid under high pressure and high temperature often leads to hazards during operation.

There is also known a modification of the method (2), steam at where in place of the hydraulic fluid at a pressure from 8.8 to 9.5 and is used at least 130 ⁰ C (U.S. Patent 3,202,558). This modified method is not suitable for impregnating agents that harden without heating.

(3) A tape that is suitable for shrinking within a certain temperature range is wrapped around the Coiled with an insulating layer provided with varnish and then subjected to heating. The shrinkage of the tape is used to firmly press the insulating layer around the reel and it pressing and forming at the same time (DT-AS 1015 526).

However, this method is not suitable for generating the necessary pressure around the insulating layer to solidify to the full extent and the dimensional accuracy and the desired insulating properties to achieve the isolated coil.

The invention is based on the object, based on the method (2), a method and to specify a device for pressing and curing such an insulated coil, thus increasing the dimensional accuracy of the insulated coil is greatly improved even in the case of a complicated shape thereof and the dielectric strength can be increased, the device being an improved Work and enable improved operational safety and also for complicated ones Coil shapes should not require specially designed heating and shaping devices.

The invention, with which this object is achieved in terms of the method, is a method for Pressing and curing one of a conductor or a bundle of conductors and a lacquer-impregnated one Insulating layer consisting of a coil, in which the coil is placed in a container, a medium is filled into the container, the coil for a certain time in the container with the medium left and then removed from the container, with the indication that as a medium Put sand into the container at least until it completely covers the entire surface of the coil will.

The principle of the invention is based on the fact that when the depth of sand filled in a container exceeds a certain value, the sand on an object placed in it is constant Able to transmit pressure level and that accordingly an insulated coil with one around a bundle of conductors or a single conductor wound and with

ίο Insulating varnish impregnated insulating layer is placed in the sand filled in a container in order to cure the insulating layer and at the same time to press the insulated coil to its desired dimensions, whereby finished coils with good dielectric strength even in the case of relatively simple means and greater operational reliability compared to the use of pressure fluids Case of complicated coil shapes are available.
Further refinements of the method are characterized in subclaims 2 to 10.

The invention also relates to an apparatus for carrying out the method, which is carried out by a container into which the sand can be filled, a valve for draining the sand from the container and means for heating the insulating layer of the insulated coil in the sand in the container is characterized. Preferably, the device has a coil support device, e.g. B. a cage for receiving a A plurality of coils, and a continuous operation for producing the insulated coils can be by alternately using a pair of containers into which the sand is to be poured.

The invention is explained in more detail with reference to the drawing: shows therein

F i g. 1 is a perspective view of a rhombic coil consisting of an element conductor and an insulating tape that is wound around it and impregnated with insulating varnish,

Fi g. 2A shows a cross section along the line II-II in Fig. 1 to show the state of a diamond coil before molding and hardening,

F i g. 2 B shows a corresponding cross section of the part in FIG. 2 A after curing is complete and Formens,

F i g. 3 schematic sketches to illustrate the individual steps of the invention Procedure,

4 shows a diagram to illustrate the dependency between the pressure of the sand and the depth of the sand filled in a container, aul Reason of trying, and

F i g. 5 shows a longitudinal section of a preferred embodiment of the device according to the invention.

F i g. Fig. 1 shows a rhombus coil 20 for use in a large-sized rotating machine Solutions as a typical example of coils to which the method according to the invention can be applied. Tue ( As FIG. 2A shows, diamond coil 20 consists of au

a conductor or bundle of conductors 22 (hereinafter referred to as a conductor for the sake of simplicity) and one Insulating tape 21, which is wrapped around the conductor 22, with the adjacent longitudinal or side overlap edges. The insulating tape 21 consists of:

an insulating fiber material which is pre-impregnated with insulating charge before the tape around the conductor 2i is wrapped around. The insulating varnish used is a thermosetting resin. The insulating tape 21 wire

24 08 73θ /

are hardened around the conductor 22 in several layers on top of each other and formed into a specific shape,

wrapped around a suitably thick insulating layer are removed from the container 25, from which

23 to form. The insulating layer obtained in this way shows the sand has been drained, whereby it is

initially an inflated or bulky appearance remains of the cage 24, and then

instead of being close to the surface of the conductor. 5 ßend subjected to cooling.

This is because the insulating layer 23 is

at this stage contains a lot of air bubbles and a pair of containers 25 is preferably expelled

therefore of low insulation strength as well as mechanical and 26 alternating in such a way that sand from

nic strength is relative to its thickness. a container 26 after curing and molding

The insulating layer 23 of the insulated coils wound around the conductor is drained through the valve 29

According to FIG. 2A, sand is now transferred to a pipe 32 by means of a sand pump 31

Genen Diuck exposed in such a way that the insulating layer and the valve 30 are conveyed to the other container 25

23 is pressed tightly to the conductor 22, as in is, in which further uncured and unshaped

F i g. 2B is illustrated without insulated coils being arranged in the insulator. This enables the

layer 23 still contains air bubbles, whereby i ₅ continuous production of the insulated coils so-

a satisfactory hardening and at the same time like the effective use of the heat of the sand,

a shaping of the insulated coil into the desired one so that there is an economical heat balance.

Shape achieved. F i g. 4 is a diagram based on experimental

It is now the individual steps of the results and shows that pressure from a relative

Method according to the invention on the basis of FIG. 3 ao shallow depth, e.g. B. 20 cm, evenly over the

explained. acts on the entire body of an insulated coil, which

Step I: The insulated coil 20 is to be hardened and shaped by hardening, using only the winding of the conductor 22 with an insulating tape against the weight of the sand,
which has been impregnated with insulating varnish, and the printing tests, the results of which are shown in FIG , Specific Gezum easy separation of the insulating layer from the sand weight 2.7) in a sealed container (26 cm suitable and against increased temperature resistant diameter) was filled, after which one is one. A plurality of iso-rubber films produced in this way on the smooth surface of the filled-in lated bobbins are then placed on mesh frame surfaces, sand, compressed air (5 kg / cm ² ) introduced and placed, which are placed one on top of the other in a cage 24 and are located in the sand after the compressed air has been introduced. resulting pressure with one buried in the sand

Step II: The cage 24, in which several iso-pressure gauges were measured. In the diagram of the measuring coils are located in a container 25 inconsistent F i g. 4 represents the ordinate the brought. The container 25 has a funnel-shaped sand pressure and the abscissa the depth of the sand narrowing to represent the emptying of. The diagram shows that the sand-sand from it easier, and from the funnel pressure when the sand depth a certain value, ie moderate bottom, a valve 28 in front of about 20 cm, is seen constant at every point. The container 25 is also provided with a steam. The same result is obtainable even when heating equipment is fitted, which is best shown in FIG. 5 40 ke ^; n additional pressure acts on the sand and can be seen. only the dead weight of the sand has an effect.

Step III: Sand 27 is passed through a valve 30 in This makes it clear that sand is a liquid

the container 25 let in, in which the isolated keiten has different behavior and to

Coils 20 are arranged, the valve 28 of the transfer of pressure simultaneously and evenly

Container 25 is kept closed. 45 over a number of arranged in a container

Step IV: The insulated coils 20 are now left to suit the insulated coils.

for a certain period of time in the sand 27, which is shown in FIGS. 5 shows an embodiment of the container has been filled. The sand 27 is shown in turn at the individual in FIG. 3 a heating device suitable for a temperature-lighter process steps, above the curing temperature of the 50 In F i g. 5, an upper container 40 contains the isodetes Insulating varnish heated, whereby the insulating layer lated coils 20, which are already the curing and 23 were subjected to the shaping steps due to the heat and at the same time the weight, while Sand cured and stripped of the insulated coils 20 for the respective lower container 41 Coil holds certain dimensions shaped, which is used to carry out the number on each other. 55 of the following process steps are ready. Sand 27 in

Step V: The sand 27 is passed through the valve 28 device 42 after the passage of the upper container 40, which has been heated by steam, for a certain period of time during which the insulated heating coils provided by the heating coils provided on this container have passed drained through a valve 44 into another container 26 below, which is left and, due to the pressure gradient between the two containers, provided separately and conveyed through a connecting pipe 45 to the lower container 41, which is ready under the same circumstances as in step II. Which is in the lower one. The arranged in the container 26 uncured container 41 filled sand 27 is heated again by a heating device 43 provided here and unshaped insulated coils 20,
here to the processes according to process steps III. After completion of the curing and molding and IV steps, like the 65 previously arranged in the container 25, the coils in the lower container 41 are subjected to insulated coils 20 that are arranged in further coils, the container 41 is hardened and to shape. shifted upward in the direction of arrow 101,

Step VI: The insulated coils 20, which were already used during the upper container 40. in the now further

ru hardening and insulated coils to be formed are or are, then lowered in the direction of arrow 102. The sand in the container 41 is then drained through a valve 46 and conveyed through a connecting pipe 47 to the container 40 again due to the pressure gradient.

In the embodiment described, the insulating varnish used is a thermosetting resin. Such types of paint are available as a curable material only with the addition of a catalyst or hardener can also be used without the use of heat in the curing process, the lacquer dried and a film is formed.

In the above embodiment, the insulated coil carries a tape that is impregnated with insulating varnish before wrapping the tape around the ladder. As an alternative, the coil can be used with an insulating layer wrapped around it as a basic insulating layer, also impregnated with insulating varnish under pressure will. In this case, the insulating layer must be covered with a special film so that the layer can be separated from the sand afterwards. An airtightness of the film is here to the covering Wrapping of the layer contrary to the case where a pressure fluid is used, not necessary.

To heat the thermosetting resin used as an insulating varnish, one can next to or instead of the use of a steam heater provided on the container to heat the sand the curing temperature of the lacquer or to a temperature above this curing temperature provide electrical heating in or on the container, and Joule heat from electricity, which flows through one or the conductor of the insulated coil, is used for direct heating of the insulating layer or preheated sand outside the container can also be filled into the container will.

Among the methods of applying pressure to the insulating layer, there is one in which pressure

can act on the sand surrounding the insulated coils from its surface, or it can a pressurized gas can also be supplied to a sealed container instead of just the weight of the sand itself. As a compressed gas

ίο can advantageously use inert gas, so that Inert gas replace air bubbles that have formed in the insulation layer * and thereby the insulation properties can improve.

In order to ensure that sand and the

covered insulated coils can be kept in close contact, a container used for this purpose can be used Seal, sucking air out of the sand to create a vacuum in the container. This helps to facilitate the firm attachment

ao pushing the insulating layer to the coil as well as to Removal of air bubbles contained in the insulating layer.

If vibration is caused in the sand to keep a maximum amount of sand in the container

the printing effect is increased considerably. The most suitable sand for use in the method according to the invention is the inactive, inorganic sand with a large specific weight. Examples of inactive, inorganic sand

are given in Table I. It has been found that Australian zircon sand with a specific Weight of 4.7 is well suited.

If the grain diameter of the sand is too large, there will be a lack of production more uniformly

Pressure. This leads to unevenness of the surface of an insulating layer with corresponding low insulation properties.

Table I.

Surname chemical formula Specific
weight warmth
conductivity
(caVcm · see,
⁰ C) Grain sizes
area
(mm) Grain shape Australian zircon sand ZrO ₂ , SiO ₂ , ZrSiO ₂ 4.7 0.015 2.0 to 0.07 spherical Australian sand SiO ₂ 2.6 0.020 2.0 to 0.07 spherical Ottawa sand SiO ₂ 2.6 0.020 2.0 to 0.07 spherical Kamulan sand SiO ₂ 2.6 0.020 2.0 to 0.07 spherical α-alumina Al ₂ O ₃ 4.0 0.090 any sharp-edged Glass bead Alkaline glass 2.1 to 2.2 0.004 any spherical

Three examples are given below, the change in the dimension of the insulated coil un according to the method according to FIG. 3 through the dielectric breakdown strength (kV / mm) de Different types of insulating layers produced in this way are shown in Table 1 materials and / or sand were used, as well as 6o indicated.

three examples obtained according to the known methods The definition of the degree of dimensional change (

for comparison purposes. One option is:

Degree of dimensional change

(Thickness of the insulating layer after curing and molding)

(Thickness of the insulating layer
- before curing and
To shape)

(Thickness of the insulating layer before curing and molding)

100 ¹ Vo.

Table II

Dimensional change (° / o)

Linear winding part head

Dielectric breakdown strength
(kV / mm)

Linear winding part head

example 1
Example 2
Example 3

Comparative example 1
Comparative example 2
Comparative example 3

5
6th

30th 3

7th
9
6th

20th
30th
19th

32
31
30th

35
16
37

30th
29
30th

15th
15th
18th

example 1

A tape (0.18 mm thick), which consisted of mica and glass fabric as cover material, was impregnated with epoxy resin as an insulating varnish and then wound around a diamond coil as shown in FIG stacked winding was obtained. A sand release film was wrapped around the insulating layer to cover its entire surface, making it easier to separate the insulating layer from the sand. Five insulated coils were thus made. These coils were placed one on top of the other in the container. To 130 ° C, the curing of the paint used, heated Australian zircon sand was filled into the container, and allowed to insulated coils in the sand in the container at 130 ⁰ C for three hours.

Example 2

The insulated coils wrapped with the insulating tape similar to Example 1 were placed under the same Curing conditions as in Example 1 with the exception that glass beads (grain size 0.297 mm) were used in place of sand.

Example 3

A tape (0.18 mm thick) made of non-woven polyester fiber material ("Byleen", a product of the Japan Byleen Company) as a covering material was wrapped around diamond bobbins as shown in FIG. 1, with the side edges of adjacent tape layers being half-overlapped, until each winding was formed six times one on top of the other, in order to produce insulated coils. These insulated coils were dried at 60 ° C. for ten hours at a pressure of 0.01 mm Hg, after which they were impregnated with solvent-free epoxy resin (adhesion coefficient 1.5 dyn. Sec / cm ² ) at the pressure of 0.05 mm Hg. A synthetic resin film ("Torayfan", manufactured by Toyo Rayon Company) was then wrapped around the insulating layer of each insulated coil to cover its entire surface and to facilitate separation of the insulated layer from the sand. The insulated coils thus prepared was allowed to stand for one hour in Australian zircon sand at 12O ⁰ C. The following examples are based on experiments using known methods.

Comparative example I.

ίο The insulating tape similar to that of Example 1 was wrapped around a rhombic coil as shown in FIG. 1, with the side edges of adjacent tape layers being overlapped and six layers being applied one on top of the other. The insulated coil produced in this way was placed in a heated to 80 ° C metal mold and allowed pressure on the straight portion of the insulated coil to act while it was heated min to 110 ⁰ C at a temperature rising rate of 5 ° C /. At this point, a pressure of 10 kg / cm ^{2 was} applied to the metal mold from four sides, followed by heating to 130 ° C. and the pressure in the mold being held at this level for three hours.

Thereafter, the metallic mold was gradually cooled to 80 ° C, and then the isolated coil removed from it.

Comparative example 2

An insulated coil similar to that of Comparative Example 1 was heated to 80 ° C in a electric furnace placed in place of the metallic mold, then with a temperature rise rate heated from 5 ° C / mm to 130 ° C and then left in it for three hours.

Comparative example 3

An insulated coil similar to that of Example 3 was made into the metallic mold under pressure Left at 120 ° C for one hour.

Table II shows the amount of dimensional change and dielectric strength in the linear part of the insulated coil and in its curved part for the insulated coils following these six examples were obtained.

It can be seen from Table II that, as far as the straight parts of the insulated coils are concerned, the isolated coils produced by the method according to the invention both in terms of degree the dimensional change as well as the dielectric breakdown strength properties show, which are essentially the same as those of the coils according to the known method, while in the curved parts the insulated coils according to the invention both in terms of degree the dimensional change as well as with regard to the dielectric breakdown strength in comparison with the insulated coils produced by the known method are very significantly improved. Farther It is found that both the straight parts and the curved parts have superior workability and have superior electrical properties.

For this purpose 3 sheets of drawings

Claims (2)

(25) a valve (28) for introducing the sand. Claims: Jn ^ 06n second container (26), a valve (30 1. Method of pressing and curing one for introducing the sand into the first container from a conductor or a bundle of conductors and (25) and a valve (29) for draining de a varnish-impregnated insulating layer consist- 5 sand from the second container (26) through egg the coil, in which the coil is connected in a container with a sand pump (31) and a pipe (32)! is arranged, a medium are in the container. is filled, the coil for a certain time 14. The device according to claim 11 dadurcl left in the container with the medium and marked that they have at least one Paarvoi is then removed from the container, io containers (40, 41), each container thereby g e k e η η ζ e i c h η e t, that as, me-pair with means for changing the mutuali dium sand in the container is equipped at least up to the position of the container with which the a. complete coverage of the entire surface of the container above or below the other containers Coil is filled is adjustable, and that in the top angeord 2. The method according to Ansoruch 1, characterized in that χ ₅ neten container (eg 40) filled sand (27 indicates that the insulating layer of the coil from it in the lower arranged container (ζ. Β after filling the sand in the container 41) through the pressure gradient in between requires a certain bar until it is fully cured.