DD204364A1 - MAGNETIZABLE NUT-SHUT-OFF STITCH FOR WINDING NUTS OF DYNAMOELECTRIC MACHINES AND MANUFACTURING METHOD - Google Patents

Abstract

The invention relates to a magnetizable slot closure rod for dynamoelectric machines and a method for its production. It refers to the construction of large dynamo-electric machines in which prefabricated coils or Windungsstaebe be inserted into open grooves. The aim of the invention is a Nutverschlussstab which has grown the loads when driving into the groove and during operation of the machine and can be efficiently manufactured. The object is to produce a slot closure rod with high impact, shear and bending strength according to a method in which many process steps for a large number of Nutverschlussstaeben be performed together. This object is achieved with a slot closure rod which is produced by a conventional separation method from prefabricated panels of the thickness of the slot closure bar. These plates are made of tensile, electrically non-conductive, and thermoset resin-dipped fibrous material which is coated with iron powder. Several such areas are stacked one above the other and processed into sheets by curing the synthetic resin with spatial cross-linking.

Description

a) Title of the invention

Magnetizable slot closure rod for winding grooves of dynamoelectric machines and manufacturing processes

b) Field of application of the invention

The invention relates to the electrical engineering. Magnetic locking means according to the invention Slot closure rods are intended for closing open winding slots in laminated packages of large dynamo machines by which pre-fabricated coils or winding rods are used.

c) Characteristic of the known technical solutions

üs numerous variants have been developed by magnetizing Nutverschlußstäben or proposed for use _s z "B _e those of ferrous sintered material and from eisenpulverhaltigem resin, z S, with reinforcement of glass" or asbestos fibers "Even wires and braided steel wire and steel packages in Nutverschlußstab and massive Nutverschlußstäbe made of steel with litter and plank insulation are known. All of these embodiments have low strength or become expensive to manufacture and to assemble. A tight fit of the magnetizable slot closure rod in the groove is important, however, because otherwise it will gradually be destroyed as a result of the intermittent magnetic attraction force by constant hammering on the ridge flank. The firmer driving into the groove but the brittleness of most magnetizable Nutverschlußstäbe counter.

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Slot closure rods made of solid steel and those with inserts made of wire mesh, however, are only applicable in special cases because of the formation of eddy currents.

d) Object of the invention

The aim of the invention is the production of a cost-effective magnetizable grooved closure rod, which withstands the stresses during driving into the groove and during operation,

e) Presentation of the essence of the invention

The object of the invention is to provide a magnetizable Hutverschlußstab with high impact, bending and shear strength, in the manufacture of which the majority of the process steps for a large number of Nutverschlußstäben is performed together.

According to the invention the object is achieved with a slot closure rod consisting of alternately arranged layers of sheets of tensile non-electrically conductive fiber material and iron powder, which are arranged parallel to the groove bottom and by spatially crosslinked, the entire slot closure rod penetrating binder to one in each direction resistant body are united. It is expedient if the binder is a thermosetting, rapidly stabilizing synthetic resin, in particular an epoxy resin.

For the production of such Nutverschiußstäbe is a method in which the fabrics of the fiber material with thermosetting, quickly stabilize

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soaked in a synthetic resin and subjected to a heat treatment * in which the synthetic resin passes into the B-state, and has been cooled down. Iron powder is then applied to the surface to be heated in an amount corresponding to the desired permeability and adhering to the surface. A plurality of such iron-powder-coated sheets are now stacked according to the thickness of the -Nutverschlußstäbe and subjected under pressure to a heat treatment to the curing of the binder.

Pie thus resulting plates are finally broken down by a separation process in Mutverschlußstäbe. It is advantageous to cause the heating of the surface of the impregnated fabrics during coating by a corresponding excess temperature of the iron powder. If a particularly high permeability is to be achieved, it is expedient to apply a thick layer of iron powder and, on top of this, a layer of the binder with which the fabric was impregnated, and to convert this layer into the B state by heat treatment. In order to produce a high density of the slot closure rods, it is advantageous to guide the iron powder coated sheets through a calender. A rationalization can be achieved in that the prefabricated of several iron-coated sheets are individually stabilized individually by brief pressing under the action of heat and that the curing takes place simultaneously in a heated platen press at several superimposed plates.

238635

f) execution

The invention is explained in more detail below using an exemplary embodiment.

, Webs of several layers of glass silk fabric are soaked with thermosetting epoxy resin. By heat treatment, the latter is converted to the B-state. On such a sheet (prepreg) hot iron powder is scattered. Since the epoxy resin softens by the heat effect of the biting iron powder, the latter adheres to the prepreg.

This is followed by an immediate cooling. The thickness of the iron powder coating adhering to the prepreg is determined by the epoxy resin content and can thus be controlled. The proportion of iron powder can be further increased by applying a thicker layer of iron powder, which is bound by an additional epoxy resin film. This is evaporated in a heating zone and transferred to the B-state. This can be followed by compaction in a calender. A further increase in the proportion of iron powder in the exemplary embodiment is characterized in that the prepreg is used in prefabricating the plates of several stacked prepreg as the lowest layer, which was coated on both sides, ie below and above, with iron powder, while the other layers are only coated above. This also achieves a better distribution of the magnetic flux in the slot closure rod. Of course, all layers can be coated on both sides with iron powder, so that a particularly high permeability is achieved.

The coating of the webs is followed by the formation of boards from it. For this purpose, the webs are cut to length, layered and pre-pressed under short-term heat to the prescribed thickness of Bitverschlußstäbe and stabilized by cooling. Each twenty such plates with non-adhesive liners are then heated in a platen press while maintaining dar thickness. In this case, the curing of the entire epoxy resin takes place, this being converted into a solid, uniform body as a result of spatial crosslinking involving the glass fiber fibers and the iron powder. From these plates, Nutverschlußstätae are produced by conventional 'separation process in a cutting department.

The so-made Itfutverschlußstäbe In Glasfaserkonetruktion are hard and at the same time flexible elastic 'and are characterized in spite of the fiberglass and üiisenelnlage by a large homogeneity. This is based on the spatial cross-linking of the binder penetrating all layers, while the high impact, bending and shear strength results from the compressive strength of the epoxy resin and the tensile strength of the glass fibers. The permeability can be optimally adapted by the means mentioned the special applications. Due to the prefabrication of plates as semi-finished all process steps except the final burning for a large number of itfutverschlußkeilen performed together, so that the Hersteilungsaufwand for the individual slot closure wedge is minimal.

Claims (6)

238635 claim: 1. Magnetisable Nutverschlußstab for open winding grooves in the laminated core dynamoelectric machines, characterized da-, by that it rial of alternately arranged layers of tensile strength of electrically non-conductive fiber mate '. and iron powder, which are arranged parallel to the groove bottom and are united by spatially cross-linked, the entire Nutverschlußstab penetrating binder to a body resistant in each direction body. 2. magnetizable Nutverschlußstab according to item 1, characterized in that the binder is a thermosetting ride s, quickly stabilizing resin, in particular an epoxy resin, 3. A process for the production of grooved bars according to item 1, characterized in that the fabrics are impregnated from the fiber material with the binder, a heat treatment in which the resin passes into the B-state »subjected to and cooled to be heated to the Surface iron powder applied in an amount corresponding to the desired permeability ~ τ ~ t «j U U w For example, it is considered that a plurality of iron-powder-coated sheets are stacked and subjected to heat treatment under pressure until the binder is cured, and the boards thus prefabricated are separated from the thickness of the keyhole bars by cutting methods into hatching bars. 4. The method according to item 3, characterized by ,, that the heating of the surface of the impregnated fabrics during coating with iron powder is effected in that the iron powder is applied with a corresponding Überteaiperatur. 5. The method according to item 3, in particular for achieving a high permeability _s, characterized in that a layer of the binder, with which the Flächenge were impregnated image is applied to a thick layer of iron powder and that this layer by a heat treatment in the. .B state is transferred. 6. Method according to item 3 for achieving a high density, characterized in that the sheets coated with iron powder are passed through a calender « 8 238635 Method according to item 3, characterized in that the panels prefabricated from a plurality of iron-coated sheets are individually shaped by brief pressing under the action of heat and that the curing takes place simultaneously in a heated platen press at a plurality of panels placed one above the other,