Note: Descriptions are shown in the official language in which they were submitted.
The ob,ect of the invention is a method for manufacturing an
insulation for high tension devices comprising insulating and metal
foil layers disposed by turns one upon the other, according to which ~
method an insulating foil is wound as a continuous band on an insulation ~ ~ `
body or the like and a metal foil band is wound in between the insu-
lating foil layers in separate pieces. ;;
To enable the prior art to be described with the aid of
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drawings, the figures thereof will now be listed.
Figure 1 is a cross section of a prior art insulator;
Figure 2 is a perspective view of the method of constructing
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the insulator of Figure l;
Figure 3 shows schematically an embodiment of the present `
invention in side view; and
! Figure 4 shows schematically an embodiment of control
apparatus for use therewith.
The ~Zeasuring transformers according to the Finnish patents
l 46,571 and 46,572, are equipped with a tubular main insulator co~Zprising
! several metal foil tube elements (a3 arranged one within the other at
least partly overlapping each other and insulating tube elements (b) `~
(Fig. 1) arranged in between the metal foil tube elements~ The main
insulator is produced by winding around a cylinder body (c) a thin
insulating foil (d) and by disposing upon it precut insulation and/or
metallized foils (e) (Fig. 2).
This method has shown the following disadvantages:
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~Z - The method is slow since every sheet must manually be placed
in its correct place. `
- The sheets get wrinkled when winding the insulation since it
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Z is difficult to stretch the separate sheets during winding. ~ ~1
Z 30 - Due to the wrinkling, the rear edge of the metallized sheets
~ is shorter than the front edge in the direction of the
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insulation axis. This produces angles at the ends of the
; metallizing cylinders, resulting in poorer voltage strength.
` In addition, the radial thickness of the insulation will
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~, unduly grow because of the wrinkling.
- The cutting oi the sheets is a separate working phase,
causing additional expenses.
The purpose of this invention is to eliminate the above disad~
vantages and to create a new and improved insulation method. ~
The method according to the invention is mainly characterized ;
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by that before the continuously fed metal foil band arrives at the
insulation body, it is provided, at a special weakening station with
spaced weakings transversal to the running direction of the band, and
that the metal foil band is retained at a retaining station at desired
moments and for desired periods of time so that the metal foil band is
torn off along one weakening situated, in the running direction of
the metal foil band, after said retaining station.
Special embodiments of the method according to the invention
are characterized by the definitions given in the claims 2 to 5.
The invention will in the following be examined more in detail
with reference to Figure 3 which shows schematically one embodiment
of the method according to the invention, and to Figure 4 which
shows schematically the principle of the control apparatus which `
controls the operation of the retaining and weakening devices. ;
According to the exemplifyling embodiments the metallized foil ~ `
1 is fed between the cylindrical insulation body 2 and the insulation
foil 3 as a uniform band which, at one point, is weakened over the
whcle width thereof. When the metallized foil 1 has completed one
1 whole rotation around the cylinder, or otherwise has reached a
1 20 desired length~ the retaining device 6 stops the running of the metallized
foil~ whereat the metallized foil 1 ls torn off along the previously
weakened portion. The retaining device 6 starts functioning when
the previously weakened portion has just been wound into the
insulation cylinder 2, whereby the end of the foil 1 that has been
torn off remains for a short while between the ins~lation foil 3
acting as drawing foil and the insulation cylinder 2. The retaining
device 6 retains the foil 1 until the insulation cylinder 2 has made
a desired angular turn. When the retaining device 6 stops its
retaining function the metallized foil 1 continues immediately to
run due to friction. The winding distance can be as long as the
metallized foil stands the frictional forces.
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1~:)6~ 36
The retaining devlce 6 comprises two rubber-covered plates 4
8 which, durin& the operation of the device~ are pressed together
by means of electromagnetically operated levers~ The compressive
force can also be effected pneumatically, hydraulically~ or by some
other suitable method. The weakening device 7 is formed with several ~;
- adjacent edges 14 which cut into the foil slits~ e.g., 10 mm wide
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and spaced 1 mm apart. ~ ~
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The edges 14 are secured to a shaft mounted in bearings
enabling the shaft to rotate. me metallized foil 1 cuts like a -
secant the circle drawn by the edges 14. In Figure 3, the weakening
device 7 is in its initial position, whereby the points of the
edges 14 are lacated somewhat above the metallized foil. Rotation ;~
of the device is hindered by a bar 15. When the control device ;
gives a wealcening impulse, the bar 15 is removed and the shaft
rotates due to compressive~ elastic or some other appropriate force~
enabling the points of the edges 14 to touch the surface of the
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metallized foil 1. When the foil 1 moves against the edges~ they
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cut slits into the foil, as has been described above. After
weakening, the device is returned to the initial position by
, 20 continuying the movement into a complete circle. ;
' The principle of the control apparatus which controls the ~ -
operation of the retaining and weakening devices is schematically --
illustrated in Figure 4. A wheel 16 rotates together with the
insulation cylinder to be prepared, rotating another wheel 17. Cam
wheels 1~ and 19 of micro-switches which control the operation of the
weakening and retaining devices rotate on a mutual shaft with the -~
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wheel 17. The desired control effect is achieved by ad~usting the
~! diameter ratio of the wheels 16 and 17 as well as by ad~usting the
length of the cam of the cam-wheels.
As to the v riations within the scope of the inventlon, ic can
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be mentioned that, departing from the above embodiment, the retaining
device 6 and the weakening device 7 can be arrarl~ed in reverse order
as far as the r~nning direction of the metal foil band il is concPrned. - :
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