DE2408738C3 - Method and device for pressing and curing an insulated coil - Google Patents

Description

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 in the production of a metallic shape with such a complicated configuration, and it is not possible to develop the same pressure everywhere with a metallic shape. In addition, s ^; rh the use of a metal mold not 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 there? Penetration of the hydraulic fluid 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 13O 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 10 15 526).

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 impregnated with ίο insulating varnish in the in a container filled sand is arranged to harden the insulating layer and at the same time the to press the insulated coil to its desired dimensions, using relatively simple means and Compared to the use of pressure fluids greater operational reliability, finished coils of good electrical quality Dielectric strength are also available in the case of complex coil shapes.

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; in it shows

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

Fig. 2A shows a cross section along the line II-II in F i g. 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,

Fig. 3 schematic sketches to illustrate the individual steps of the invention Procedure,

Fig. 4 is a diagram for the position of 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 as a typical example of coils to which the method of the present invention can be applied. The diamond coil 20 consists, as FIG. 2A shows, of: a conductor or conductor bundle 22 (always referred to as conductor in the following for the sake of simplicity) and an insulating tape 21 which is wrapped around the conductor 22, the adjacent longitudinal or side edges overlapping . The insulating tape 21 consists of an insulating fiber material which is pre-impregnated with insulating lacquer before the tape is wound around the conductor 2i. The insulating varnish used is a thermosetting resin. The insulating tape 21 win

wrapped around the conductor 22 in several layers in order to form a correspondingly thick insulating layer 23 . The insulating layer obtained in this way initially has an inflated or bulky appearance instead of lying close to the conductor surface. This is because the insulating layer 23 contains a lot of air bubbles at this stage and is therefore poor in insulating strength and mechanical strength relative to its thickness.

The insulating layer 23 wound around the conductor according to Fig. 2A is now transferred to one by sand Subjected to pressure such that the insulating layer 23 is pressed closely against the conductor 22, as in FIG Fig. 2B is illustrated without being in the insulating layer 23 still contain air bubbles, whereby one a satisfactory curing and at the same time achieved shaping of the insulated coil into the desired shape.

The individual method steps of the method according to the invention will now be described with reference to FIG. 3 explained.

Step I: The insulated coil 20 is made by winding the conductor 22 with an insulating tape, which has been impregnated with insulating varnish, and to prevent sand from sticking, a Film wound around the insulated spool 20, which is used to easily separate the insulating layer from the sand suitable and resistant to elevated temperatures. A plurality of isolated ones made in this way Coils are then placed on mesh shelves which are placed one above the other in a cage 24 are.

Step II: The cage 24, in which there are several insulated coils, is placed in a container 25. The container 25 has a funnel-shaped narrowing bottom to the emptying of To lighten sand therefrom, and on the funnel-shaped bottom a valve 28 is provided in the middle. The container 25 is also equipped with a steam heating device, which is best shown in FIG. 5 can be seen.

Step III: Sand 27 is admitted through a valve 30 into the container 25, in which the isolated Coils 20 are arranged, the valve 28 of the container 25 being kept closed.

Step IV: The insulated coils 20 are now left for a certain period of time in the sand 27, which is in the Container has been filled. The sand 27 is heated to a temperature by means of a heating device heated above the curing temperature of the insulating varnish used, creating the insulating layer 23 as a result of the heat and at the same time the weight of the sand hardened and applied to the respective insulated coil is molded of certain dimensions.

Step V: The sand 27 is after a certain period of time during which the isolated Coils held therein are discharged through valve 28 into another container 26 below, the provided separately and ready to receive sand under the same circumstances as in step II is. The uncured and unshaped insulated coils 20 disposed in the container 26 are then here the processes according to process steps III and IV as those previously arranged in container 25 Subjected coils to thereby harden and shape more coils.

Step VI: The insulated coils 20, which are already cured and shaped into a specific shape are removed from the container 25 from which the sand was drained, placing them on the Ge Footprints of the cage 24 remain, and then ßend subjected to cooling.

As can be seen from the above explanation, it is preferable to operate a pair of containers 2f and 26 alternate in such a way that sand au; a container 26 after curing and former

ίο the isolated coils drained through valve 29 and conveyed by means of a sand pump 31 through a pipe 32 and the valve 30 to the other container 25 is, in which further uncured and unshaped insulated coils .sind are arranged. This enables the

continuous production of the insulated coils as well as the effective use of the heat of the sand, so that there is an economic heat balance. F i g. 4 is a diagram based on experimental results and shows that pressure from a relative

so shallow depth, e.g. B. 20 cm, evenly over the acts on the entire body of an insulated coil, which is to be hardened and shaped, with only the weight the sand was used.

The printing tests, the results of which are shown in FIG. 4th

are shown were carried out in such a way that sand (grain diameter 0.285 mm, specific gravity 2.7) was filled into a sealed container (26 cm diameter), after which a Rubber film on the smooth surface of the filled

Sand, introduced compressed air (5 kg / cm ² ) and measured the pressure resulting in the sand after the introduction of the compressed air with a pressure gauge buried in the sand. In the diagram of FIG. 4 showing the measurement results, the ordinate represents the

Sand pressure and the abscissa represents the depth of the sand. The diagram shows that the sand pressure, if the sand depth has a certain value, d. H. exceeds about 20 cm, constant at each point will. The same result is obtainable, too, though

no additional pressure acts on the sand and only the weight of the sand has an effect. This makes it clear that sand has a different behavior from liquids and is to Transfer of pressure simultaneously and evenly

via a number of insulated coils arranged in a container.

F i g. FIG. 5 shows an embodiment of the for use with the individual in FIG. 3 illustrated Process steps suitable device.

In Fig. 5, an upper container 40 contains the isolated Coils 20, which have already been subjected to the curing and shaping steps, during a lower container 41 contains the insulated coils 20, to carry out the number of successive

the following process steps are ready. Sand 27 in upper container 40 heated by steam from the heater provided on that container 42 comes, is drained through a valve 44 and due to the pressure drop between

two containers through a connecting pipe 45 to the lower container 41 promoted. The sand 27 filled in the lower container 41 is here provided heating device 43 is heated again

After completion of the curing and molding

steps of the arranged in the lower container 41 insulated coils 29, the container 41 is displaced upwards in the direction of the arrow 101, while the upper container 4 ·, in which now further

insulated coils to be hardened and shaped are arranged, 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 varnish are curable as a curable Material only with the addition of a catalyst or hardener without the use of heat applicable in the curing process, whereby the lacquer is dried and a film is formed.

In the above embodiment, the insulated coil carries a tape that is impnigned 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 use in addition 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. Inert gas can advantageously be used as the compressed gas, so that the Inert gas replace air bubbles that have formed in the insulation layer and thereby improve the insulation properties can improve.

To achieve that sand and the insulated coils covered with it are kept in close contact a container used for this purpose can be sealed, the air being sucked out of the sand to create a vacuum in the container. This helps to make it easier to press firmly the insulating layer to the coil and to remove air bubbles contained in the insulating layer at.

If vibration is created in the sand in order to bring a maximum amount of sand into 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 1. 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 uniform Pressure. This leads to an unevenness of the surface of an insulating layer with corresponding low isolation conditions.

Table I.

Surname chemical formula Specific
Weight warmth
conductivity
(cal / cm see,
⁰ C) Grain sizes
Area
(mm) Kornforin Australian zircon sand ZrO ₂ . SiO ,, 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 »-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 and

according to the method according to FIG. 3 due to the dielectric strength (kV / mm) of the

Different types of insulating layers produced in this way are shown in the tables

materials and / or sand were used, and 60 indicated.

three examples, which are carried out according to the known methods The definition of the degree of dimensional change-

for comparison purposes. One option is:

Dimensional Change Degree -

(Thickness of the insulating layer after curing and molding)

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

(Thickness of the insulating layer before curing and molding)

• 100 per cent.
609 635/293

'f-

ίο

Table II

Abniessiings- Dielectric Dia change ('Vn) impact resistance (kV / mm) Linear winding Linear winding Part head Part head

each insulated coil is wound to cover its entire surface and to facilitate separation of the insulated layer from the sand. The isolated coil st produced was allowed in austra lischem zircon at 12O ⁰ C a Suinde are following examples are based on tests nacl

known procedures.

example 1
Example 2
Example 3

Comparative example 1
Comparative example 2
Comparative example 3

5
6th

3
30th

7th
9
6th

20th
30th
19th

32
31
30th

35
16
37

30th
29
30th

15th
15th
18 Comparative Example I.

example 1

A tape (0.18 mm thick), which consisted of mica and glass fabric as a cover material, was with Epoxy resin impregnated as an insulating varnish and then wrapped around a rhomb coil according to FIG. 1, where the side edge !! adjacent tape drawer each half-lap until a six-fold layered winding is obtained was. A sand release film was wrapped around the insulating layer to cover its entire surface and so make it easier to separate the insulating layer from the sand. So five coils were clicked manufactured. These coils were attached to each other in the container. At 1 30 'C, the curing temperature of the paint used, heated Australian zircon sand was poured into the container, and the insulated coils were allowed to stand in the sand in the container at 130 ° C. for three hours.

Example 2

The one with the insulating tape similar to Example I. Wound insulated coils were hardened under the same curing conditions as in Example I with the Except that glass beads (grain size 0.297 mm) were used instead of sand.

Example 3

A tape (0.18 mm thick), which consisted of non-woven polyester fiber material ("Bylecn". Product of the Japan Bylecn Company) as a covering material, was wound around diamond spools as shown in FIG a six-ply winding was formed to make 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. See / cm ² ) at the pressure of 0.05 mm Hg. Then a film made of synthetic resin ("Torayfan", product of the Toyo Rayon Company) was wrapped around the insulating layer. The insulating sheet similar to that of Example 1 was wound around a diamond coil as shown in FIG. Tape layers were overlapped and six bearings were placed one on top of the other. The insulated coil thus prepared was placed in a metallic mold heated to 80 ° C, and pressure was applied to the straight part of the insulated coil while it was ^{heated to 110 °} C at a temperature of 5 ° C / min At this point, a pressure of 10 kg / cm- was applied to the metallic mold from four sides, which was followed by heating to 130 ° C. and the pressure in the mold was 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

One of the most similar to Comparative Example 1, insulated coil was placed in a heated to 80 ° C electric furnace instead of the metal mold, then heated to 130 ⁰ C at a temperature rising rate of 5 'C / MRA and then allowed to stand for three hours therein.

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 noted that both the straight parts

as well as the curved parts have superior workability and electrical properties exhibit.

For this purpose 3 sheets of drawings

Claims (13)

ι 2 (25) a valve (28) for introducing the sand Patent claims:> a 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 the a lacquer-impregnated insulating layer consist- 5 sand from the second container (26) through a the coil, in which the coil is connected to a container sand pump (31) and a pipe (32) is arranged, a medium are in the container. is filled, the coil for a certain time 14. Apparatus according to claim 11 thereby left in the container with the medium and marked as having at least a pair of 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 a pair with means to change the mutual dium sand in the container is equipped at least up to the position of the container, with which one complete coverage of the entire surface of the container above or below the other container Bobbin is filled in is adjustable, and that in the uppermost 2. The method according to claim 1, characterized in that the container (e.g. 40) is filled with sand (27) indicates that the insulating layer of the coil is inserted from it into the lower-level container (e.g. after filling the sand into the container 41) through the pressure gradient between forderbis for complete curing on a certain bar is. 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 a 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 1 to 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 or before 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 or characterized in that it is cured on the in by means of heating. However, to arise Container to cover the curing time it contains air bubbles in the paint or in the 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 of the sand poured into the container have an effect on the bubble content 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, so 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. so the following procedures 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 lacquered or lacquered item a) a container (e.g. 25), in the sand insulated coil is filled in a metallic form with ⁵⁵ dimensions according to a certain shape. b) a valve (e.g. 28) for draining the ^tun S of ^the insulated coil arranged to shape the insulated sand from the container and ^s p ^{u! e to this} given shape as well as m c) Means (7, B. 42) for heating the insulating ^dcr insulating layer or air bubble layer contained in the lacquer of the insulated coil in the sand in the Bc ^to expel by compression (CH-PS 2 87 691). I ₁ JjI ₁₀ P 60 According to a modification of 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 support 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 apparatus according to claim 11, characterized in that 65 is flowed through (GB-PS 9 67 235).
characterized in that a pair of containers (25, according to this method can be good insulation 26) is provided 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 ,