DE2552919A1 - METHOD AND DEVICE FOR PERFORATION OF RAIL MATERIALS - Google Patents

Description

FROM KREISLER SCHÖNWALD MEYER EISHOLD FUES FROM KREISLER KELLER SELTING

PATENT LAWYERS Dr.-Ing. by Kreisler + 1973

Dr.-Ing. K. Schönwald, Cologne Dr.-Ing. Th. Meyer, Cologne Dr.-Ing. K. W. Eishold, Bad Soden Dr. J. F. Fues, Cologne Dipl.-Chem. Alek von Kreisler, Cologne Dipl.-Chem. Carola Keller, Cologne Dipl.-Ing. G. Seifing, Cologne

5 Cologne ι November 25, 1975

DEICHMANNHAUS AT THE MAIN RAILWAY STATION

Ke / Ax / Bn.

Bakelite Xylonite Limited,

Enford House, 139 Marylebone Road, London N.W, 1 / Eiiglarid Method and device for perforating

The invention relates to a method and a device for perforating web materials, in particular Polynier-

foils or sheets, by means of electrical discharges.

It has already been proposed to perforate flat materials with the aid of electrical discharges. After the publications In the prior art, it is common practice to use needle-shaped electrodes, e.g., sharp pencils, blunt pencils or rod-shaped components with a hemispherical end " turn around areas of high electric field strength between such an electrode and a second electrode in a perforating machine operating with electrical discharges use. The needle-shaped electrode or the needle-shaped electrodes can be arranged so that they are longitudinal an endless path, e.g. on an endless belt, a rotating drum or on rotating arms, while the second electrode can also move around one or more perforation lines in the running direction of the web or one Pattern of perforations created by the relative movement of the

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Telephone: (0221) 234541-4 Telex: 8882307 dopa d Telegram: Dompatenf Cologne

Electrodes and the direction and speed of movement of the web is controlled to generate. Through suitable Arrangement of the pins, as described for example in DT-PS 20 14 000, the discharge point, i.e. the Point at which the distance between the pins and the spaced second electrode is at is the smallest, can be moved in the transverse direction, i.e. the discharge point can be moved by rotating a shaft which has a ' A number of closely spaced pins around the circumference of the shaft in the form of a single spiral, the extending radially from the shaft, reciprocating v / ground.

Pen-shaped electrodes are a simple means of To generate areas of high electric field strength for the transmission of perforating discharges, however, they have a number of disadvantages. The electrodes are subject to severe erosion during operation, as a result of which uneven electrode spacing and uncontrolled fluctuations in the perforation result. The electrode gap is preferably kept as low as possible to ensure that the energy in the spark discharge is not used up when overcoming an unnecessarily large air gap. Hence there is only a very small gap through which the web runs, which increases the likelihood of the web tearing by a such a pin-shaped electrode results.

In DT-PS 20 14 000 it is proposed to use an air or To use gas flow in the electrode gap to move the discharge point back and forth along the electrodes. With such an arrangement, an area which has a lower density than the surrounding areas becomes and through which the discharge preferentially goes, generated in the gas,

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and a flow of air or gas causes the region of low density to reciprocate and consequently the reciprocation of the discharge point along the electrodes. According to another suggested method a mask is used for the reciprocation, which is moved back and forth. The mask created by the The perforating device used in each case cannot be perforated by itself, is provided with slits, the so are arranged so that only one slot is open in the gap between the electrodes during the to-and-fro movement and a discharge passes through the slot and perforates a web at a point in communication therewith. the The latter proposals have decided practical and cost limitations as they are in addition to the basic electrode systems and the power supply and control require additional equipment.

The invention relates to a perforating method and a perforating device that uses electrical discharges work and use an electrode system consisting of a set of electrodes and practical problems, resulting from the use of pin-shaped electrodes and complicated reciprocating arrangements, which require additional equipment in addition to the electrode system and power supply as well as control, avoids.

The method according to the invention for the perforation of Web materials by electrical discharges is characterized in that one has a web of a flat Material through an electrode system consisting of a set of electrodes so that the web passes through a gap between a first electrode and a

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second electrode of the electrode system is running, where ' either the first or the second electrode is under an electrical potential which is at high frequency relative to the potential of the other electrode changes so that peak potential differences between the first and of the second electrode have such a size that electrical discharges between the first and the second electrode and occur through the web, with at least one of the two electrodes rotating and is designed in such a way that an area of its surface which at any moment is in closest proximity to the surface of the other electrode is an area that is · over the opposite surface of the other electrode is scanned in a direction that has at least one component parallel to the axis of rotation, so that separate perforations are produced in the web by the electrical discharges.

The invention further comprises a device for perforating web materials with the aid of electrical discharges with an electrode system comprising an electrode set from a first electrode and from a has second electrode, which have such a distance that a material web to be perforated 'between them can be carried out, and those with components to create a potential difference between them and a controller can be connected that changes the potential difference at high frequency so that During operation, peak potential differences between the first and second electrodes are of such an order of magnitude have electrical discharges passed between the electrodes and through one between them and web to be perforated take place. The device

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is characterized in that at least one of the two electrodes is rotatable and designed so that during the rotation an area of their surface that!

at any moment the closest distance to the j Surface of the other electrode, one above the opposite surface of the other electrode j lying area is scanned in a direction that has at least one component parallel to the axis of rotation. |

As flat materials for the perforation with the aid of the method and the device according to the invention Flat dielectric materials that have dielectric strengths at least in certain areas are suitable that are so low that electrical discharges between the electrodes and through the flat material can take place and, where this is possible through these areas, the webs perforated will. The dielectric strength of a suitable sheet is preferably uneven due to its thickness in such a way that in the plane of the web areas with the required low dielectric strength Areas with relatively high dielectric strength are adjacent. I.

For example, webs of an irregular ¹ or interrupted or fibrous nature, for example paper and paper-like materials, are suitable as flat materials. Particularly suitable and preferred are plastic films or sheets that

a) have cavities or cells that form areas with lower dielectric strength and after can be formed by one or more different methods, e.g.

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1. Use of physical or chemical blowing agents

2. addition of additives other than propellants, which, when physically deformed, e.g. by stretching, create cavities in the material and, for example. consist of inorganic or organic fillers or pigments, with subsequent Deformation and

3>. Leaching of soluble additives

b) have areas that are exclusively due to the The presence of additives, in contrast to the case mentioned under a) (2), results in a lower penetration have strength than neighboring areas, or

c) contain areas with lower dielectric strength, resulting from physical or chemical treatments, e.g. surface treatments and surface modifications, e.g. embossing.

It is also provided within the scope of the invention, larger Form perforations in dielectric sheet materials that already have small continuous perforations Contain that as areas with lower dielectric strength than adjacent non-perforated areas and therefore more easily penetrable by electrical discharges, especially when the small ones continuous perforations essentially uniform are distributed. In the case of flat materials that contain voids, the areas are their dielectric strength is less than that of neighboring areas, usually through the cavities or cells even formed due to the lack of polymer. in the

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In the case of flat materials that do not contain cavities, but pigments or fillers, the Areas of lower dielectric strength formed by the areas occupied by the filler particles, while embossed materials can have these areas due to their uneven thickness. Behn materials that can be described as paper-like can have areas with lower dielectric strength as a result of a randomly oriented fiber structure, and these areas are normally essentially evenly distributed. A pre- ■ However, added paper-like material is a plastic film or sheet that contains voids or cells. Particularly preferred for the “method according to the invention are the cellular plastic films described in the applicant's British patent application No. 35 701/7 ^ described v / earth.

The web material to be perforated and the perforated web formed therefrom can be part of a larger one Structure or component, e.g. a laminate, for example made of a polymer film or plate, which is covered with a same or different material is connected, or a multilayer structure, the layers of which are not are glued together. The sheet material to be perforated can before the perforation by any known film treatment process, which the subsequent Do not affect perforation or, if so, do not affect it in an undesirable way, treated will. The perforated webs can also be subjected to these treatments at will.

Suitable polymers from which the preferred polymer films or plates can be produced are suitable

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thermoplastic resins, preferably by polymerization including copolymerization of ethylenically unsaturated Monomers are produced. The particularly preferred polymers include homopolymers and copolymers of olefins, e.g., commercially available polyethylenes such as high pressure polyethylene, medium j pressure polyethylene and low pressure polyethylene, copolymers of olefins, especially ethylene, with low Amounts up to, for example, 10% by weight of one or more organic compounds copolymerizable therewith are polymerizable and contain multiple bonds, such as those in compounds that have an ethylenic Bond ^ C = CC ^ are present, e.g. VinylaryOe, such as styrene, o-methoxystyrene, p-methoxystyrene, m-nitrostyrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, p-phenylstyrene, m-phenylstyrene and vinyl naphthalene; Vinyl and vinylidene halides, including vinyl chloride, vinylidene chloride, and vinyl fluoride; Vinyl ester, like Vinyl acetate, vinyl propionate, vinyl butyrate, vinyl chloroacetate, vinyl chloropropionate, vinyl benzoate and vinyl chlorobenzoate; Acrylic acid and a- ^ alkyl acrylic acid, their Alkyl esters, amides and nitriles, such as acrylic acid, chloroacrylic acid, methacrylic acid, ethacrylic acid, methyl acrylate, Ethyl acrylate, butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, methyl methacrylate, butyl methacrylate, Methyl ethacrylate, ethyl ethacrylate, acrylamide, N-methylacrylamide, N, N-dimethylacrylamide, methacrylamide, N-methyl methacrylamide, N, N-dimethyl methacrylamide, Acrylonitrile, chloroacrylonitrile, methacrylonitrile and ethacrylonitrile; Alkyl esters of maleic acid and fumaric acid, such as dimethyl maleate and diethyl maleate; Vinyl alkyl ethers and ketones, such as vinyl methyl ether, vinyl ethyl

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ether, vinyl isobutyl ether, 2-chloroethyl vinyl ether,!

Methyl vinyl ketone, ethyl vinyl ketone and isobutyl vinyl j

ketone, also vinylpyridine, N-vinylcarbazole, N-vinyl- j

pyrrolidone, methylethylvinylacetamide, ethylmethylene j

malonao and propylene, polypropylene and polybutene-1 | as well as derivatives of these compounds including the
halogenated polyolefins such as chlorinated polyethylene

and chlorosulfonated polyethylene.

Homopolymers of vinyl halides, such as vinyl chloride and vinyl fluoride, are also suitable as thermoplastic resins, Vinylidene fluoride ;? Vinyl esters of carboxylic acids,

such as vinyl acetate, vinyl stearate and vinyl benzoate {· vinyl

i ethers, for example vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Chlorotrifluoroethylene / tetrafluoroethylene; j hexafluoropropylene; unsaturated carboxylic acids and their derivatives, such as acrylic acid, methacrylic acid, methyl acrylate, methyl α-chloroacrylate, ethyl acrylate, methyl methacrylate, acrylamide, acrylonitrile and methacrylonitrile,
and copolymers of the * abovementioned vinylidene monomers with α, γ-unsaturated polycarboxylic acids and
their derivatives such as maleic anhydride, diethyl maleate, dibutyl fumarate, diallyl maleate and dipropyl dialeate. More preferred as examples, of the particularly
preferred olefin polymers different polymers
Materials may be mentioned: homopolymers and copolymers
of vinyl chloride, such as polyvinyl chloride,
Vinyl chloride-vinyl acetate copolymers and vinyl chloride "acrylonitrile copolymers, the homopolymers of vinyl aromatic hydrocarbons and their ring-halogenated derivatives, such as styrene, o-chlorostyrene, p-chlorostyrene, 2,5-dichlorostyrene, 2,4-dichlorostyrene, p-methylstyrene, p-ethylstyrene, a-methylstyrene, vinyl

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naphthalene and copolymers of these vinyl monomers with one another and with other vinyl monomers.

Other suitable thermoplastic resins are: polycarbonates, polyoxymethylene and oxymethylene Alkylene oxide copolymers, polyurethanes, polyesters including polyethylene terephthalate, polyamides, including in particular polycaprolactam, polyhexamethylene adepamide, poly-11-aminoundecanoic acid, ABS terpolymers and Mixtures of the abovementioned polymers and copolymers including mixtures with rubber, such as natural rubber, ethylene-propylene rubbers, butyl rubber, Polyisobutylene, polybutadiene and butadiene-styrene rubbers.

The thermoplastic resins can contain known additives, e.g. lubricants, lubricants, anti-blocking additives and Contain plasticizers to improve the processing properties of the polymers and the handling of the polymer films or As an electrode system, an electrode set is used for the purposes of the invention, which consists of a first electrode and a second electrode. One of the following is appropriate in each case Electrodes used as first and second electrodes:

a) a metallic conductor,

b) a metallic conductor that rests on a dielectric Material is attached to that on another

"metallic conductor rests,

c) a metallic conductor that rotates on a dielectric material within a concentric Metal housing, which can be coated with a dielectric material, is attached, and

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d) a metallic conductor which is provided with a coating of dielectric material.

The surface of an electrode can therefore consist of an electrically conductive or dielectric material.

Capacitive means are preferably used as a feature of the electrode set in order to reduce the charge transfer in! to localize and / or limit any electrical discharge i. A dielectric can be used as the capacitive means Layer are used that are in close proximity to the dielectric during the course of the process Railway material is located and must be such that the total capacitance of the first electrode and a second electrode of the set. System with the intermediate track is not completely destroyed by the electrical breakdown of the web and its discharge perforation. When using an electrode in the form of a metallic conductor attached to a dielectric material is, the capacitance of the system is allowed despite the breakdown of the dielectric path are not completely destroyed by perforation. It is usually only desired to have either a first electrode or a second electrode of a set has a capacitive means. The capacitance of the system depends on the dielectric material used in the electrode construction is used, and can be adjusted by suitable choice of material and dimensions v / earth.

In order to achieve a desired high perforation density in one

given web at high running speeds of web l to achieve, it can be advantageous, within the framework of the invention, more than one first electrode in combination: with one or more second electrodes in a ί set of electrodes and one or more electrode] sets to use in the electrode system. The simplest possible electrode system is a system that consists of a set of electrodes consisting of a first electrode and a second electrode. A ! An extremely complex electrode system can, for example, comprise a number of sets of electrodes which are arranged transversely to the direction of travel and / or along the direction of travel of the web, each set of electrodes of several first electrodes and several second ones Electrodes and at least one of the first and second electrodes of each set rotates and j and is referred to hereinafter as the scanning electrode, and each axis of rotation is normally not parallel to the direction of travel of the web and so that the rotation is scanning in one direction causes the at least one component lying in a plane parallel to the plane of the web, transverse to the running direction the train has.

However, an electrode set is preferred as the electrode system, which consists of a first electrode and a second electrode facing each other or, more preferably, a single first electrode or a second electrode which is opposite a plurality of separately operating second or first scanning electrodes, consists. These separately working scanning electrodes

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consist of several conductors that are electrically connected by-: are isolated from each other and can be arranged so that they are independent, but preferably together so rotate that area of the surface of each conductor, which is at any moment in greatest Proximity to the surface of the other electrode, the area or part of the area overlying the opposite surface of the other electrode I is scanned. I.

if the electrode set consists of a single first Electrode and a single second electrode, which face each other, v / eist the scanning electrode preferably a plurality of profiles, each profile being shaped so that during rotation an area on its surface which at any moment is in closest proximity to the surface of the other electrode is located, part of the over the opposite surface of the other electrode the lying area. For example, a sensing electrode can be a number of electrical disk-shaped Have sections which in a suitable manner i on a shaft at an angle to and at a distance from one another are attached to each other. As an alternative, it can consist of one wire or a plurality of wires that are attached helically on a metal profile.

Separately working second scanning electrodes can, for example, consist of a large number of wires, which are helically wound around a dielectric layer which is applied to a metallic conductor and is rotatably mounted so that an area on the surface of each wire, which is in any-

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a moment in the closest proximity to the surface of the,

first electrode in the opposite position to j

is located, at least part of the j

surface of the first electrode ^! '

gropes. I.

According to the definition, a scanning electrode can consist of little! at least part of the surface of a body of revolution j exist. The scanning electrode is preferably on! ordered so that it rotates in such a way that | its scanning surface moves tangentially to a plane, which are generally parallel to the plane of the

forging web material. is in the area of the electrode gap. This way it becomes a more even ^! Gap separating the scanning surface of the scanning electrode and the surface of the other electrode facing it.

It is considered essential that the discharge point or points between the first Electrode and the second electrode of a set a major surface of the running web material in one Crossed direction that forms an angle of preferably 90 ° with the direction of travel of the web, so that the effective distance between the charge points the electrodes at .the discharge and a previously formed Perforation is a result of their movement on paths that are not parallel to each other. In this way it is possible to do a proportionate

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large perforation density with a selected diameter j

Record speed of the path, a selected turning '-.

speed of the rotatable electrode and a low | chose frequency of change of applied electrical

To reach potential because these variables thus being suitable]

represents v / ground that perforations in imme- diate j

close proximity of the electrode gap itself '

undesirably to places of dielectric ί

Weakness from the subsequent discharges j

prefer to walk rather than make new perforations. ;

I The surface area of the sensing electrode that is in closest proximity to the surface at any given moment of the other opposite electrode, can consist of a single unit of area or of a multitude of j number of individual areas exist in such a way that the individual j surface or the plurality of individual surfaces scans an area that is above the other electrode surface each of the plurality of individual surfaces, if present, at least a portion scans this area in such a way that an overall scan can be achieved in each case.

The to-and-fro movement of the discharge in a direction across the v.xv trajectory results from the to-and-fro movement of areas of high electric field strength between the electrodes along the electrode gap. These areas of high electric field strength are largely dependent on the shape and design of the scanning electrode, in particular on the shape of the area on the surface of this electrode, which is brought one after the other into the jar to the surface of the other opposite electrode. The scanning electrode is designed so that the electric field strength

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at different points between the electrodes along their effective length (according to j Definition) is higher or lower. Who at the j Carrying out the method, a web material is passed through between the electrodes, it is back and forth exposed areas of different electric field strengths, the instantaneous areas generate high electrical stress in the web material at the point or points in the electrical field, where the field strength is high. Each of these areas of high electrical stress can affect the body be for a perforation, especially if it comes from the peak potential difference, and especially then if he is using a range of proportional low dielectric strength in the web material.

When, when carrying out the method according to the invention, the web is guided through the gap between the first and second electrodes in such a way that it is in contact with an electrode, it preferably touches an electrode which, owing to its design and shape, is spatially limited concentration of the eieio ₁ tric field in such a V / else causes the j field strength is sufficiently high at the peak potential difference to the web which is in contact with the electrode surface to be perforated. As a practical matter, however, it is preferred that there be essentially no contact between the web and one of the electrodes.

For example, if the electrodes are arranged so that the scan is carried out in a direction perpendicular to the

direction of the path between the first and second elec- j trode takes place in a plane parallel to the plane of the web 'it is evident that the width of each part of the

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Web material to perforate through the passage between the electrodes in the method according to the invention is, cannot be greater than the effective length of the electrodes, i.e. the maximum width of the to i perforating web is limited to the effective length of the first and second electrodes. This effective Length can be defined as the length of the area that lies above the surface of an electrode that passes through j an area on the surface of the sensing electrode in the direction at least one component to the axis of rotation the scanning electrode is scanned. Due to the relative complexity of the shape of a scanning electrode the device according to the invention is preferably adapted so that different web widths or Perforate parts of the web by changing the length of a sensing electrode. It makes sense that a Electrode set can be arranged so that the scan takes place in a direction that is not perpendicular runs in the direction of travel of the web. In this case! the effective length of the electrodes is shortened and the j Width of the path that can be carried out between the first and the second 'electrode for perforation, wrestles. This measure can of course not only be applied to a device on webs of different Adjust widths, but also to make a device on the perforation of a selected part of the width to park a web material.

The adaptation of the device according to the invention to the! Perforation of different web widths or parts of the j

Bahn can also be done by other methods, e.g. by

a) Use of covers or masks, e.g. additional web material that is not used during the process is perforated, and

b) suitable control of the power supply to the electrodes.

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These methods can also be applied to the pre-j direction according to the invention so that a The web can be perforated in selected areas spaced in the longitudinal direction of the web can. For example, perforations can be made in a wide variety of patterns at will will.

In the following descriptions of two preferred electrode systems each for use in the procedure and in the device according to the invention, a first electrode, which can be connected to a suitable voltage source and control, and a second electrode or several second electrodes explained that can be connected to earth. This allows the electrodes are connected as required to components with which the potential difference at high frequency can be set and changed between the electrodes. Provided that the isolation requirements for safe and perfect operation; of the device are observed, there is also the clear-i no further reason given the following description; why the second electrode or the different second ones Electrodes not connected to the voltage source and j the first electrode should be connected to earth. j

In a first preferred embodiment of the invention, the electrode system consists of a set of electrodes, which consists of a first electrode in the form of a metal sheet and an assembly of separately operating second scanning electrodes, which are connected by a rotatable metallic cylindrical shaft, a sleeve reliably fastened around the shaft made of suitable dielectric Material and a large number of wires are formed on the peripheral surface of the sleeve with Length spacing from each other are helically wound, the axes of the V / end In with the axis of rotation of the rotatable Wave essentially coincide. The rotating

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bare metal wave can be placed on earth, so that everyone Wire can be capacitively connected to earth. When each wire has one or more complete turns around forms the sleeve of dielectric material, the linear length of the first electrode is preferably selected that never two points or areas on the same wire with the first electrode when discharging in Connection are. If this is not the case, there could be two identical paths between the first electrode and a wire while only one discharge is taking place. This discharge can be from either of the two Connections run out and therefore control the reciprocation of the discharges in one direction operate across the perforating web, the reciprocating movement of the perforation by rotation the wire helix around an axis at an angle to the direction of movement of the web material passing through between the electrodes is achieved. Any change in the ' Impact strength of the sheet material or any slight change in the distance between the first and the second Electrode which coincides with the occurrence of a peak in the potential difference can be a preferred i Discharge along one of these otherwise identical routes' and cause a preferred perforation of the web at this point. Preferably, however, an electrode j set used in which each of the wires of the group of second sensing electrodes make a helical turn substantially completed around the periphery of the dielectric sleeve. If on the dielectric sleeve a big one When the number of wires is attached, the spacing between the wires should be such that no arcing occurs and there is an unacceptably high level of tracking between the wires; when the device is in operation. If it is ensured that the current supplied to the first electrode, the to achieve the desired perforation density does not greatly exceed the current required, and that the electrode spacing at the minimum for the

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forming web material and much less than that Distance is maintained between adjacent wires of the group of second scanning electrodes, the runs preferred path of a discharge immediately between the first electrode and a second scanning electrode and by the path that runs between them. In order to largely eliminate the formation of odors, the Group of second electrodes preferably uses a dielectric sleeve material that is not in use carbonized, such as an acrylic resin, or other materials are used that can carbonize when they are electrical Stresses are subjected, but which are protected with a suitable dielectric protective material, e.g. a layer of a polymeric substance, for example a silicone rubber as it is known under the trade name "Silastic 14O IiTV" (manufactured by Dow Corning Ltd.) is available is, coated v / ground, which acts as both glue between the wires and the dielectric sleeve and as a coating, the charring of the dielectric sleeve to a large extent turns off, serves. In use, the group of second scanning electrodes can be connected by any means, e.g. an electric motor via a pulley and a drive belt.

In a second preferred embodiment of the invention, the electrode system comprises a set of electrodes, which consists of a first scanning electrode, which will be described below, and a second electrode, which is formed by a grounded conductor sheathed with a dielectric material and having the shape of a Rotary body, preferably has a cylinder and is arranged so that it is around his preferably main axis lying in a plane parallel to the plane of the material to be perforated in connection with the

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scanning first electrode rotates, wherein the rotation primarily serves to damage the electrode decrease in use. The scanning first electrode in this embodiment consists of one rotatable metal shaft on which at least one, but preferably a plurality of thin metal profiles, all of which have substantially the same thickness, is rigidly attached. The sensing first electrode is preferably made from a metal cylinder by machining in such a V / eise, that the profiles with the shaft consist of one piece, but the profiles can also be separated a metal sleeve which can then be attached to the shaft. Every profile is on the Shaft so arranged that the generalgenei ^ .e plane in the it lies, forms an angle of more than 0 ° but less than 90 ° with the axis of the shaft, and that during each complete revolution of the shaft an area of its surface which is at some distance in closest proximity to the second electrode, at least part of the area above this second electrode the lying area. Preferably are each

i Profile and its attachment designed in such a way that during, this rotation the said area on the profile j at least part of the area above the second electrode lying area at a substantially constant distance from the surface of the second Electrode scans. The profiles can be elliptical, for example, with the major axis of the profile forms an angle of more than 0 ° but less than 90 ° with the axis of the shaft, the smaller of which Axis forms a right angle to the axis of the shaft.

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If a large number of profiles are used, are these preferably attached so that their general planes are parallel to each other and so that they are arranged in the same way and at equal intervals on the shaft. The scope of each profile goes through therefore during the rotation of the shaft at least one Part of the width of a web to be perforated if, for example, its axes are not parallel to the direction of travel of the path and each of these axes lies in a plane substantially parallel to the plane of the path, wherein the peripheral area or the surface of each profile successively voltage source points for an electrical Discharge forms.

The spaces between adjacent profiles of the scanning first electrode in the second preferred one Embodiment can be with any suitable Insulating material are filled in to give the electrode a sufficient degree of rigidity, but in particular, in order to avoid a gap due to a contact between the web and the first sensing electrode and vacuum forming the web to be perforated and moving the web transversely to its direction of travel between to largely switch off the electrodes. The same measure can of course also be taken to provide a smooth peripheral surface "at the group of second scanning electrodes in the first preferred embodiment to build. In this way, the gaps between the wires can be filled with a suitable insulating material. When carrying out the method using the second preferred embodiment of the apparatus, both the scanning first electrode and the second electrode rotated with a suitable drive, wherein for example an isolated drive for rotating the first scanning electrode and for example an independent one

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Friction drive used for the rotation of the second electrode or a drive dependent on the isolated drive will. Of course, at least the second electrode could by touching rr.it rotates with the running path, however, as already mentioned, it is preferred avoid contact between the web and the electrodes.

It is evident that by changing the thickness of the as capacitive means used dielectric material and for example in the first preferred embodiment by changing the diameter and length of the wires of the assembly of second sensing electrodes, the capacitance of a system can be changed. So it is with a given path, a given distance of the first and second electrodes, a given running speed of the web, a rotating speed of the scanning electrode and for a given peak potential difference between the first and second electrodes, the size of the Perforation as this is a function of the energy of the perforating discharge, which in turn is a Function of the capacitance of the system is.

The distance between the first and second electrodes is preferably chosen so that the web material between the; Electrodes can be carried out without in undesirable way either the rotation of a rotatable electrode or to disrupt the movement of the web. This distance can be adjustable. Preferably, however, the electrodes in maintained a distance greater than that for proper perforation of a given web in a suitable one It is necessary to set the peak potential difference, but this allows free unhindered running. Preferred j

wisely, the distance is no greater than about 1 mm. ^!

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The first and second electrodes can be connected to components with which a potential difference between the electrodes can be generated, and on components that are able to change this potential difference with high frequency, be connected. For this purpose, components that have an electrical potential to the first or place a second electrode and control it so that it is changed at a high frequency, and grounding components for the other electrode used. A change can be used as the mechanism for supplying and controlling an electrical voltage A power generator can be used that delivers a high enough peak voltage to cause an electrical discharge to produce which perforate a given thickness of a web material by the method according to the invention able. Any device can also be used as a device for supplying and changing an electrical voltage Direct current generator are used, which components are assigned that this voltage in a suitable manner modulate in such a way that a potential is generated which is changed as required at a high frequency. A suitable one Device for supplying an alternating voltage is a generator of the trade name "Lepel", the one Voltage and a current, which can be changed over wide ranges, is able to deliver.

The device according to the invention is with a mechanism provided to drive the rotatable scanning electrode. Mechanical or electrical, for example, are suitable for this purpose mechanical devices.

The perforating machine can also be provided with devices that the web material through the gap between transport the spaced apart first and second electrodes. All pre-

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directions that the Ushnmaterial essentially continuously preferably in the crease-free state, feed into the gap at a speed that is suitable for the purpose to achieve the required perforation density for given settings of the perforation control. These Device generally consists of at least one group of driven rollers, which the web with sufficient Take tension to get it from a supply roll of a suitable sheet material to be perforated with sufficient Pulling voltage through the electrode gap. There is also a winding station for receiving the suitably perforated web, generally consisting of a tensioning device driven roller of known type, on which a spool for receiving the perforated fed to it Bahniuaterials is put on.

When running the method according to the invention are The size and density of the perforations of the web functions of a number of variables. The most important variables are based on the electrode system used, the scanning speed and therefore the rotational speed the scanning electrode, the peak voltage difference between the first and second electrodes, and the frequency or frequency of the peaks of the potential difference, the thickness, evenness and type of the web to be perforated and the speed of travel of the web between the first and second electrodes, normally these can V / earth variables controlled during the course of the method according to the invention in most cases. Variable ^ which naturally 'normally during the course of the procedure cannot be influenced are, for example, the thickness, consistency and type of the material and the Structure or design of the electrodes. It should be noted, however, that those associated with the web material Variables during the manufacture of the Bahuni material and any subsequent one made before the perforation Treatment of the web material influences and

e ue r_Lj

609824/0285

The transverse spacing of the perforations in the running web; depends for example at least on the distance of the helical twisted wires from each other in the first preferred embodiment of the invention., from the scanning ' speed and frequency of the peaks of the potential difference between the first and second electrodes away. The distance between the perforations in the longitudinal direction is a function of at least the passage speed the path and the speed, for example the change in the potential difference between the first and second electrodes. The size and density of the perforations are at the same time a function of at least that Potential difference between the first electrode and the second electrode, the throughput speed of the Path and the size of the perforations, a function at least of the capacitance of the system that the first and second electrodes with the path passing between them. The lower the throughput i speed of the web, the more likely it is that a discharge does not form a new perforation, but rather passes through the next previously formed perforation, this last perforation being made larger will. An increase in the throughput speed of the Web can therefore have the effect of increasing the number of perforations while increasing their relative numbers Size is reduced. It has been found that by using two equal power sources, e.g., electrical Lepel generators connected in parallel, large perforations, but essentially no larger number as compared to the perforations formed in an equal sample of the sheet material that is being used the same set of electrodes and under the same physical conditions, but using only one power source has been perforated. This effect can also be achieved simply by increasing the size of the used power source can be achieved. Unwanted slit-shaped perforations can be avoided, by, for example, the frequency with which the potential

809824/0285

- 27 tial difference between the first and second electrodes:

changes, the speed of the web and J the rotation speed of the scanning electrode is set! will. !

It is generally useful to carry out the process according to Invention under normal atmospheric conditions of the j

Environment. For the sake of simplicity, the invention will be described herein as if it were. However, if desired, the process can also be carried out under reduced pressure and / or in the presence of another Gas or vapors other than air. For example, an inert gas can be used when it is desired to limit the extent of surface oxidation of the web under the influence of the electrical charges. It can also be advantageous to avoid working in particularly humid air in which the Discharge characteristics are different from those in dry air.

The method and the apparatus are described more below with reference to the figures.

1 schematically illustrates, as a side view, a method using an electrode system, which consists of a set of electrodes in connection with the first preferred embodiment of the invention has been described.

FIG. 2 is a top plan view of that shown in FIG Electrode system consisting of a set of electrodes of the type used in connection with the first preferred |

ι embodiment of the invention has been described.

Fig. 5 is a top plan view of an electrode system which consists of a set of electrodes of the type used in connection with the second preferred embodiment of the invention and an alternative to that described with reference to FIG. 1 and FIG Represents electrode system. J

B09824 / 0285

Figure 4 is an illustration of a third electrode arrangement.

In the arrangement shown in Figure 1, a dielectric Web material 1 from a delivery roll 2, which works against a brake, not shown, in Direction of the arrow over a group of pulleys "5 through a gap 7 between a first electrode 4 and scanning second electrodes of the electrode group guided. The first electrode 4 is connected to a source 4A of an electrical voltage which is high Frequency is changed. The electrode is attached to an adjustable electrode holder 6, of which the however, the first electrode is electrically isolated. As components for guiding the web 1 through the gap 7 is a Group of driven rollers 8 available, which grip the web material and put it under sufficient tension hold to continuously pull it through the gap. The winding station for receiving the perforated Web material consists of a driven roller 9 on which a take-up reel for the reception of you fed web is placed. Further pulleys 10 and 11 contribute to the control of the guidance of the web to the take-up spool. The electrode group 5 is rotatably mounted and is not shown by a Drive set in rotation.

The schematic representation of the perforation process in FIG. 1 only applies to one type of perforation process and is not intended to be limiting. For example, the device according to the invention be adapted so that they are part of an overall process for producing the sheet-like material is working. In such a case, the delivery roll 2 would normally be omitted, since the web is immediate from the stage of production of the sheet material, for example from an extrusion process to • Production of foils or plates, is fed.

FIG. 2 is a plan view of the electrode system shown schematically in FIG. 1, which is shown in FIG Form a first electrode 4 and a spaced-apart group 5 of a plurality of scanning electrodes includes. The group of scanning second electrodes, generally designated 5 in FIG comprises a metal sleeve 5A rotatably mounted on and electrically connected to the rotatable metal shaft 12 is. The shaft can be rotated with any suitable drive (not shown). This metal sleeve is grounded via the shaft 12 (not shown) and made with a tight-fitting sleeve Γ3 provided dielectric material. The plurality of scanning second electrodes consists of wires 14, i those on the dielectric sleeve 13 and above this sleeve | connected to the metal shell 5A and parallel to each other are arranged so that each wire forms a complete helical turn. The ends of the wires are on the dielectric sleeve Ij5 by means of a tape of suitable insulating material 15, for example one Polyvinyl chloride tape attached. In the area, the assembly formed from the wires 14 rotates from the second Scanning electrodes with the rotatable shaft 12 so that the distances 7 between the opposite Surfaces of the electrodes remain essentially constant over the entire length of the first electrode 4. This first electrode consists of a metal sheet, e.g. a sheet steel that is rigid and insulated on one Kalter 6 is attached, which is attached to a (not shown}) support frame.

609824/0285

- 20 -

FIG. J5 shows schematically in section an electrode system which consists of a set of electrodes as described in connection with the second preferred embodiment of the invention and is an alternative to the set of electrodes described with reference to FIG. This electrode system includes a scanning first electrode, which is generally designated 16 and is arranged at a distance from a second electrode, which is generally designated 17. The first electrode and the second electrode are both rigidly attached to rotatable shafts 18 and 18, respectively, and are thereby electrically connected to these shafts. The shafts are mounted in a suitable manner and are rotated by any drive (not shown), for example a mechanical or electro-mechanical drive, and are separated from one another by a gap 20 which can be adjusted with suitable components (not shown). The scanning first electrode 16 consists of a cylindrical metal rod 21 which has been processed so that it has a row of eight equidistantly spaced elliptical

4/0281

has raised profiles 22, the major axes of which are at an angle of about 75 ° to the axis of the cylindrical j Rods run parallel to each other. When the first electrode rotates, feel the peripheral areas of these profiles j collectively the area overlying the surface of the effective length of the second "electrode" in one direction parallel to the axis of rotation and at a practically constant distance from this surface. The profiles are shaped and arranged so that they appear circular when viewing the electrode 16 from the end face and lie concentric to the shaft. The distances between adjacent profiles 22 are covered with a suitable insulating material 23 filled in so that the overall cylindrical shape of the electrode is maintained for the reasons already mentioned. The second electrode is made from a metal cylinder 25, which via the shaft 19 i can be grounded and with a sleeve 26 made of dielectric | Shem material is enclosed. In operation there is an electrical potential for its change at high frequency Care is taken to the first electrode 16 from a (not shown) voltage source and controller placed over a slip ring 24 attached to the shaft 18, while the shaft 19 with its (not shown) Bearings is grounded. The discharge perforation of a web is across the web width passing through the gap 20 runs and is scanned by rotating the first electrode 16 through a series of electrical Reaches discharges between the peripheral regions of the profiles 22 and the surface of the dielectric sleeve 26, the discharges taking place when the electrodes reach peak potential differences.

Figure 4 shows another embodiment of the for Method used device. With this arrangement, an assembly 31 is made up of scanning first electrodes through a dielectric rod 32 and wound around the rod Wires formed (as described with reference to Figure 2 or Figure 3). The rod 32 is rotatable

609824/0285

stored within a metal housing 33, the inside of which is covered with a dielectric material 3 ^ · is. The housing 33 is provided on one side with an opening 35, so that the rod 32 through the opening 35 can be inserted into the housing. The second electrode 36 faces the opening 35. The case is grounded at 37.

This arrangement has the advantage that the assembly 3I from the first electrodes is cheaper to maintain than those wound with wire, with a dielectric covered metal roll, and it has the additional advantage that the connection to earth via a variable resistor 38 can be produced, whereby the time constancy of the system can be regulated, and that it is also possible to adjust the distance between the housing 33 and the rod 32, for example by means of a screwing device 39 and thereby changing the capacitance of the system.

The perforated flat materials produced according to the invention are used, for example, there, where it is desired to use a sheet material which, if not perforated, will fit into is undesirably relatively impermeable to water, water vapor or air. As examples of such Applications include packaging in perforated packaging materials where air is trapped or trapped gas can be a problem if the same packaging material is in the non-perforated State is used. Plastic bags or the like. Can through the perforation according to the method according to of the invention can be made relatively safe for children. In particular, it is to be expected that the Products of this process Use for wrapping baked goods such as bread, for filtration and for wound dressings can be found where the use of such a film allows the wounds to "breathe" and the light weight

60982 ^ / 0285

Favors removal of a bandage from a wound. j

ι The method and apparatus according to the invention will j further illustrated by the following example.

Example;

The apparatus used was essentially that shown in Figures 1 and 2 and referenced as shown, but with the following additional details:

The first electrode consisted of an aluminum strip 30.5 cm long and 1.6 mm thick. An assembly of 72 second scanning electrodes was formed by 72 helically wound copper wires with a wire size of 25 SWG, which ^{were fixed parallel to each other at intervals of 3 * 2} mm on a glass sleeve using double-sided adhesive tape so that each wire formed a complete helical turn. The glass sleeve was fastened tightly to a mild steel sleeve, which in turn was fastened to a grounded solid shaft made of mild steel and was thereby electrically connected to this shaft. The glass sleeve consisted of toughened borosilicate glass and had an outside diameter of 10.2 cm and an inside diameter of 9 * 65 cm. The ends of the wires were tied to the glass sleeve with polyvinyl chloride tape. The mild steel shaft was pivoted and rotated by a drive with a motorized belt that ran over a pulley attached to the shaft. The second electrodes had an effective length measured parallel to the axis of the shaft of 32.8 cm. The wires were isolated from each other with the help of the double-sided adhesive tape and the glass sleeve and connected capacitively to earth.

The smallest distance between the first electrode and the scanning second electrodes became 1 mm set. Regulated current became the first electrode

609824/0285

by connecting to a Lepel generator of the designation HFSG-2, which is available for 1.5 kVA with a power setting of 5.5 on the scale (power dial setting). One 30.5 cm wide and 25 / U thick

/ ί cellular film made of high density polyethylene, which according to j that in Example 1 of British application 35781/74 of The process described by the applicant was perforated using this device.

The second electrode assembly rotated at 1440 rpm.

The table below shows the number of holes that

ρ
were formed per m in the cellular film, the number of holes formed per second and the average hole size together with the maximum and minimum hole sizes as a function of the throughput speed of the film. The number and size of the holes were measured with a microscope for a series of samples of the perforated film.

Running speed hole sizes (/ U) number d.gebil- number d.prq

^dlslc X: ^polle

' cut 1

O .05 158 572 24 876,000 13 Hz, 600 O .10 104 286 24 67O, 000 20. at least 750 O .15 98 268 29 632,000 29. 400 O .20 85 268 29 540,000 3>. 400 The one used here Includes the term "high frequency" Frequencies up to just under to 50 however, normally se a frequency of 1 kHz applied.

60982A / 0235

Claims (1)

Expectations 1 ^ Procedure for perforating sheet materials electrical discharges, characterized in that the path is surrounded by first and second electrodes. Electrode system leads so that the path through a gap between the first and second electrodes runs while there is a high frequency potential difference between the first and second electrodes so that at a peak potential difference between the tips of the first and second electrodes, that are very close, electrical discharges take place that pass through the web and thereby forming separate perforations in the web, from the first and second electrodes at least one electrode is rotated and is formed so that an area on its surface that is in closest proximity to the surface of the other electrode at any moment, one over the opposite surface of the other electrode scans in a direction which has at least one component parallel to the axis of rotation. 2) The method according to claim 1, characterized in that a web of dielectric material, the realms that have a lower dielectric strength than other areas, perforated. 3) Method according to claim 1 and 2, characterized in that that one perforates a fiber web. 4) Method according to claim 1 to J>, characterized in that a paper web is perforated. 609824/0286 5) Method according to claim 1 and 2, characterized in that polymer films or plates are perforated. 6) Method according to claim 5 * characterized in that that polymer films or sheets containing cavities or cells are perforated. 7) Method according to claim 1, 2, 5 and 6, characterized in that that one polymer films or sheets, the cavities formed by the decomposition of a blowing agent or contain cells, perforated. 8) The method according to claim 7, characterized in that a sheet material containing cavities or cells is perforated, which is formed by extruding a mass consisting of a linear olefin polymer and a blowing agent to form a cellular extrudate and then stretching the extrudate by an amount that is one A stretching ratio of at least 1.1: 1 in the longitudinal and / or transverse direction, corresponds to has been produced. 9) Method according to claim 1 and 5 to 8, characterized in that that one perforates a flat material made of homopolymers of olefins or copolymers of olefins with up to 10% by weight of at least one copolymerizable monomer: i is. ' 10) Device for perforating web materials with the aid of electrical discharges, characterized by an electrode system having at least one first electrode and at least one second electrode, that have such a distance that the train 609824/0285 material can be passed between them, at least one of the electrodes being rotatable and is designed so that during rotation an area of its surface that is closest to each other to the surface of the other electrode, one above the opposite surface of the other electrode lying area in a direction that at least one component is parallel has to the axis of rotation. 11) Device according to claim 10, characterized in that each electrode is provided with components, which can be connected to a potential difference source and control elements are provided, with which the potential difference can be changed at high frequency. 12) Device according to claim 10 or 11, characterized in that each electrode consists of a metallic Conductor, a metallic conductor attached to a dielectric material called the rests on another metallic conductor, a metallic conductor that rests on a dielectric Material attached and partially covered by a metal housing coated with a dielectric material can be, is surrounded, or consists of a metallic conductor with a coating dielectric material is provided, each electrode being the same or different from any other electrode can be different. Device according to claim 10 to 12, characterized in that that the electrode system consists of a single first electrode and a single second electrode, the first electrode 609824 / 028S facing the second electrode. 14) Device according to claim 10 to 12, characterized in that that the electrode system consists of a single first electrode or a single second electrode facing a plurality of independently operating second or first electrodes, consists. 15) Device according to claim 10 to 14, characterized in that the rotatable electrode consists of a plurality of metal disks which are attached to each other on a shaft with Austand and at an angle of more than 0 ° and
Shaft are inclined. of more than 0 ° and less than 90 ° to the axis of the 16) Device according to claim 10 to 14, characterized in that that the rotatable electrode consists of at least one wire which is helical around a shaft is tortuous. 17) Device according to claim 16, characterized in that each individual helical turn is formed is that never two points or areas on the same wire are in closest proximity to the other Electrode. 18) Device according to claim 10, characterized by an electrode system comprising a first electrode, which consists of a sheet metal electrode, and an assembly of second electrodes in the form of a rotatable cylindrical metal shaft around which a sleeve made of dielectric material is securely fastened is around which a plurality of wires are wound at a distance from one another, the rotatable 609824/0285 Shaft can be grounded so that each wire is capacitively coupled to it. 19) Device according to claim 10, characterized by a first electrode in the form of a rotatable metal shaft with a multitude of thin metal profiles rigidly attached to it or molded in one piece, all of which have substantially the same thickness and are each inclined at such an angle that the plane of each profile forms the same angle of more than 0 ° and less than 90 ° to the axis of the shaft, and a second electrode in the form of a conductor made up of a rotatable cylindrical metal core connected to is encased in a dielectric material and can be grounded. O"- 20) Device according to claim 10, characterized by a first electrode in the form of a rotatable cylindrical shaft made of dielectric material, around which a multitude of wires is wound in a helical manner at a distance, and a shaft at a distance partially surrounding metal housing that can be earthed, and a second made of sheet metal Electrode. 609824/0285