AT523203A1 - Production of a continuous tube by changing the color during production - Google Patents

Abstract

A method for producing a tube for a vehicle tire that can be filled with a gas or gas mixture, in particular air, which comprises the following steps carried out with or without intermediate steps: Providing an open, provided with or having at least one electromagnetic wave absorbing material emitted by a laser (4) Hose section (1), - inserting a first end section (2) of the hose section (1) into a second end section (3) of the hose section (1), - welding overlapping areas of the first end section (2) and the second end section (3) by means of of the laser (4) in a laser transmission welding process, the at least one absorbing material changing its absorption properties in a wavelength range of the electromagnetic waves emitted by the laser during irradiation with the electromagnetic waves emitted by the laser, a transmission coefficient of at least est an absorbent material is increased with continued irradiation in this wavelength range.

Description

The invention relates to a method for producing a tube for a vehicle tire that can be filled with a gas or gas mixture, in particular air, which comprises the following steps carried out with or without intermediate steps:

- Providing an electromagnetic emitted with at least one of a laser

Open tube section provided with waves absorbing material,

- Insertion of a first end section of the hose section into a second end section of the hose section,

- Welding overlapping areas of the first end section and the

second end section by means of the laser in a laser transmission welding process.

The invention also relates to a tube for a vehicle tire.

A method of the type mentioned at the beginning has become known from DE102018202798A1. In the known method, a layer which at least partially absorbs laser light is applied between sections of the hose section that are to be welded to one another. The disadvantage of the known method, however, is that if the laser light is only partially absorbed by the absorbing material, the energy input into it will be insufficient and this layer can only partially melt. On the other hand, if the absorption coefficient of the absorbent material is selected too high, when the hose is welded to laser transmission welding, the absorbent material is no longer penetrated by sufficient laser light to ensure reliable welding of the layers underneath to one another. Due to the difficulties just mentioned, in the hoses produced with the known method in the area of

Welded joints mechanical weak points occur.

mechanically well resilient are to be produced.

This object is achieved according to the invention with a method of the type mentioned at the outset in that the at least one absorbent material changes its absorption properties in a wavelength range of the electromagnetic waves emitted by the laser during irradiation with the electromagnetic waves emitted by the laser, a transmission coefficient of at least an absorbing material is increased with continued irradiation in this wavelength range.

The solution according to the invention enables a very efficient use of the energy of the radiation emitted by the laser, since at the beginning there is a high absorption rate and thus a high conversion of electromagnetic energy into thermal energy. With increasing duration of the welding, the absorbing material becomes more transparent, which means that more laser radiation can pass through this material unhindered and the energy of the penetrating radiation is available for the welding of subsequent layers with increasing process time. Another very advantageous effect that can be achieved with the method according to the invention is that, with increasing transparency of the absorbent layer, the welding area cools down during the welding process, which is associated with a significant shortening of the manufacturing process.

In order to achieve a superficial melting of the tube piece during the welding, it has been found to be advantageous that at least one boundary layer of the absorbent material is applied between these areas before the welding of the overlapping areas.

A through-welding of the hose piece in a single operation and a very efficient process management are promoted by the fact that each end section of the

Two pieces of hose viewed in the circumferential direction of a lateral surface of the hose

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Section of the first end of the hose - the second section of the second end of the hose is compressed.

The productivity and efficiency can be increased even further by welding the overlapping areas of the first end section and the second end section from the same side of the package, the first section of the second tube end with the first section of the first tube end and first then the second section of the first hose end with the

second section of the second hose end is welded.

In order to ensure that there is no unwanted welding of the inside of the hose, it has been found to be advantageous that the at least one boundary layer of absorbent material between the first section of the second hose end and the first section of the first hose end and between the second section of the first hose end and the second section of the second tube end is applied, an area free of the absorbent material being created between the first section of the first tube end and the second section of the first tube end.

It has been found to be particularly favorable that the tube piece provided has at least one transmission coefficient greater than or equal to 0.7, in particular greater than 0.8, particularly preferably over, for electromagnetic waves emitted by the laser, in particular in a wavelength range between 900-1200 nm 0.9 having base material. Due to the high transparency of the base material of the tube piece in the area of the laser radiation, it can be ensured that the welding process is controlled very specifically and it is ensured that a welded connection is only made at the points provided for it.

An embodiment has proven to be particularly advantageous in which an opening is made in the hose piece through which a valve with a valve base is inserted, an area of the valve base being larger than an area of the opening and the valve base being inserted into the hose piece the opening on an inner side of the hose section closes this and the valve base made of a thermoplastic in a region of the electromagnetic waves emitted by the laser has an absorption coefficient of less than 0.3, in particular less than 0.2, particularly preferably less than 0.15 Material, in particular the same material as the tube piece, is made, wherein the valve base and / or the tube piece have the absorbent material and / or are provided with this and are welded to one another by means of the laser. In this way, a very high level of tightness and a significant increase in mechanical stability in the area of the valve can be achieved. In contrast to conventional solutions, in which a connection area between valve and hose always represents a mechanical weak point through which air can escape from the hose, in this variant

this area mechanically reinforced and better sealed.

of the first end portion and the second end portion of the hose piece.

A significant increase in the production speed can be achieved in that the tube piece is cut off from a longer tube before it is made available, the absorbent material already being inserted into or applied to a base material of the longer tube. According to this variant of the invention, the absorbent material does not need to be applied to the cut piece of tube afterwards, for example by brushing on, spraying on, dipping, etc., but is already in or on the base material of the longer tube.

piece.

It has been found to be particularly advantageous that the hose piece is a thermoplastic elastomer, in particular TPU, TPE-A, TPE-E, TPE-O, TPE-S, TPE-U, TPE-V or a non-thermoplastic plastic, for example a silicone elastomer, in particular comprises an LSR (Liquid Silicone Rubber) material or at least one

made of these materials.

For the absorbent material, it has turned out to be particularly beneficial to

at least one absorbing material consists of color pigments, in particular organic color pigments, which at least partially disintegrate when heated and lose the absorption properties in the wavelength range emitted by the laser, or the-

se includes.

In addition, it is particularly advantageous with regard to achieving the desired properties of the absorbent material if the at least one absorbent material comprises an organic solvent such as acetone, ethanol or methyl ethyl ketone (MEK) and organic color pigments. This variant of the invention is particularly suitable for subsequent coating, as the solvent of the absorbent material

evaporates after its application and the organic color pigments remain.

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produced according to any one of claims 1 to 13.

The invention together with other advantages will be described below with the aid of some non-restrictive

kender exemplary embodiments explained in more detail. The drawing shows schematically:

1 shows an apparatus for carrying out the method according to the invention.

According to the method according to the invention for producing a tube for a vehicle tire that can be filled with a gas or gas mixture, in particular air, a closed ring or torus is formed from an open tube piece 1. For this purpose, a first end section 2 of the hose section 1 is inserted into a second end section 3 of the hose section 1. Overlapping areas of the first end section 2 and the second end section 3 are then connected to one another by means of a laser 4 in a laser transmission welding process. An overlap length is typically between 2 mm and 10 mm. An overlap length of approx. 5 mm has proven to be particularly favorable. A power between 20-100 W has proven to be favorable for the laser 4. The power of the laser is particularly preferably between 30 - 40 W.

The laser 4 can be, for example, a carbon dioxide laser, a neodymium-yttrium-aluminum-garnet laser, a high-power diode laser, a 2 µm

Diode Pumped Solid State Laser or similar laser systems.

The hose piece 1 has at least one of a laser 4 in the overlap area

emitted electromagnetic wave absorbing material. The absorbent

make cuts.

During irradiation with electromagnetic waves emitted by the laser 4, the absorbing material changes its absorption properties in the wavelength range emitted by the laser 4. A transmission coefficient of the absorbent material is increased with continued irradiation in this wavelength range. An absorption coefficient of the absorbing material for electromagnetic waves emitted by the laser, in particular in a wavelength range between 900-1200 nm, changes during the irradiation by means of the laser by greater than 0.7, in particular

greater than 0.8 to a value less than 0.2, in particular less than 0.1.

The absorbing material consists of or comprises color pigments which, when heated, at least partially disintegrate and lose the absorption properties in the wavelength range emitted by the laser 4. Organic color pigments which absorb in the infrared range and which have a very small absorption coefficient, for example less than 0.2, in a spectral range outside the infrared range have proven to be particularly suitable. For example, the absorbent material can be present as a dissolved dye and comprise an organic solvent such as acetone, ethanol or methyl ethyl ketone (MEK) and organic color pigments.

Suitable absorbent materials have become known, for example, under the name Clearweld® from Gentex Cop., Carbondale (US). The Clearweld products with the designations LD120, LD130 and LD140, for example, have proven to be particularly advantageous.

Before welding the overlapping areas between these areas, a boundary layer made of the absorbent material is applied. This can be done, for example, by applying the absorbent material in liquid form. Alternatively or additionally, however, the absorbent material can already be embedded in a material of the tube piece 1 or already as a coating on the tube piece 1

are present. The absorbent material can, for example, as a film with a preferred

7th

The hose piece 1 has a base material for electromagnetic waves emitted by the laser, in particular in a wavelength range between 900-1200 nm, a transmission coefficient greater than or equal to 0.7, in particular greater than 0.8, particularly preferably greater than 0.9,

The hose piece 1 is preferably made of a thermoplastic elastomer, in particular TPU, TPE-A, TPE-E, TPE-O, TPE-S, TPE-U, TPE-V or a non-thermoplastic plastic, for example a silicone elastomer, in particular an LSR ( Liquid Si

licone rubber) or comprises at least one of these materials.

The tube piece 1 can, for example, have a wall thickness between 0.1 mm and 1.5 mm, in particular between 0.2 mm and 0.6 mm, particularly preferably between 0.3 mm and

0.4 mm.

The tube piece 1 can be cut off from a longer tube, the absorbent material already being inserted into or applied to a base material of the longer tube. For example, the base material of the tube can serve as a matrix for the absorbent material. Alternatively or additionally, the absorbent material can be applied as a coating to the base material of the tube. However, the absorbent material can also be applied to the piece of tubing that has already been cut to length, for example by spraying, brushing on, by means of a dipping process, etc.

Each end section 2, 3 of the hose piece 1, viewed in the circumferential direction of a jacket surface of the hose, has two opposite and one to the other.

closing sections 5, 6, 7, 8. During the welding of overlapping areas of the first and second end sections 2, 3, a package with a sequence of first subsections 5 of the second hose end 3 - first subsections

Section 6 of the first hose end 2 - second section 7 of the first hose end

A glass plate 12 and a pressure plate 13 can be used to compress the package. The laser 4 is arranged on the side of the glass plate 12 and electromagnetic radiation emitted by this penetrates the glass plate 12 and the

separate layers of the package during the welding process.

The overlapping areas of the first end section 2 and the second end section 3 are welded from the same side of the package, whereby first the first section 5 of the second hose end 3 with the first section 6 of the first hose end 2 and then the second section 7 of the first hose end 2 with

the second section 8 of the second hose end is welded.

Between the first section 5 of the second tube end 3 and the first section 6 of the first tube end 2 and between the second section 7 of the first tube end 2 and the second section 8 of the second tube end

a boundary layer of absorbent material can be applied in each case.

Between the first section 6 of the first tube end 2 and the second section 7 of the first tube end 2 there is a loading area free of the absorbent material.

is created rich by leaving this area uncoated.

An opening 9 can be made in the hose piece 1, for example by cutting or punching. The valve 10 with a valve base 11 can be inserted into the hose piece 1 through this opening 9. An area of the valve base 11 is larger than an area of the opening 9. After being inserted into the hose piece 1, the valve base 11 closes the opening 9 on an inner side of the hose piece 1. The valve base 11 is made of a thermoplastic in an area of the laser 4 electromagnetic waves emit an absorption coefficient of less than 0.3, in particular

less than 0.2, particularly preferably made of material having less than 0.15.

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The valve base 11 is welded to the hose section 1 from the same side as the welding of the overlapping areas of the first end section 2 and the second end section 3 of the hose section 1. As a result, the laser 4 only needs to be displaced linearly with respect to the stationary hose section 1 or vice versa which simplifies the process considerably. As an alternative to moving the laser 4, radiation emitted by the laser 4 can also be deflected, for example by means of a mirror, so that the end regions 2, 3 and the valve base 11 are welded to the hose piece 1 simultaneously. Self-evident

Lich several lasers 4 can also be used at the same time.

A hose produced using the method according to the invention has an absorption coefficient in an overlap area of the first and second end sections 2, 3, measured normal to a lateral surface of the hose, in a wavelength range between 900-1200 nm of less than 0.3, in particular less than 0.2 , particularly preferably less than 0.1. This is due to the change in the absorption properties of the absorbent material due to the welding process.

A hose according to the invention can have a wall thickness between 0.1 mm and 1.5 mm, in particular between 0.2 mm to 0.6 mm, particularly preferably between 0.1 mm, and particularly preferably between 0.1 mm and 1.5 mm, outside the overlapping areas of the end sections 2, 3 with one another and of the valve base 11 with the hose inside. 3 mm to 0.4 mm. In the overlapping areas, the hose has approximately twice the wall thickness than in the other areas of the hose.

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Claims (1)

1. A method for producing a tube for a vehicle tire that can be filled with a gas or gas mixture, in particular air, which the following with or without intermediate steps includes: - Providing a with at least one of a laser (4) emitted electromagnetic open tube (1) provided with material absorbing cal waves, - Introducing a first end section (2) of the hose section (1) into a second end section (3) of the hose section (1), - Welding overlapping areas of the first end section (2) and the second end section (3) by means of the laser (4) in a laser transmission welding process, characterized in that the at least one absorbing material changes its absorption properties in a wavelength range of the electromagnetic waves emitted by the laser during irradiation with the electromagnetic waves emitted by the laser, a transmission coefficient of the at least one absorbing material being increased with continued irradiation in this wavelength range . 2. The method according to claim 1, characterized in that before the welding of the overlapping areas between these areas, at least one boundary layer of the absorbent material is applied. 3. The method according to claim 1 or 2, characterized in that each end section (2, 3) of the tube piece (1), viewed in the circumferential direction of a jacket surface of the tube, has two mutually opposite and adjoining subsections (5, 6, 7, 8), wherein during the welding of overlapping areas of the first and the second end section to form a package with a sequence ter section (5) of the second hose end (3) - first section (6) of the first 11 4. The method according to claim 3, characterized in that the welding of the overlapping areas of the first end section (2) and the second end section (3) takes place from the same side of the package, the first section (5) of the second hose end (2 ) with the first section (6) of the first hose end (2) and then the second section (7) of the first hose end (2) with the two th section (8) of the second hose end (3) is welded. 5. The method according to claim 2 and one of claims 3 or 4, characterized in that the at least one boundary layer of absorbent material between the first section (5) of the second tube end (3) and the first section (6) of the first tube end (2) and is applied between the second section (7) of the first hose end (2) and the second section (8) of the second hose end, with between the first section (6) of the first hose end (2) and the second section (7) of the first Hose end (2) one of the absorbent free area is created. 6. The method according to any one of claims 1 to 5, characterized in that the provided hose piece (1) has at least one for electromagnetic waves emitted by the laser, in particular in a wavelength range between 900-1200 nm, a transmission coefficient greater than or equal to 0.7, in particular having a base material greater than 0.8, particularly preferably greater than 0.9. 7. The method according to any one of claims 1 to 6, characterized in that an absorption coefficient of the at least one absorbing material for electromagnetic waves emitted by the laser, in particular in a wavelength range between 900-1200 nm, during the irradiation by means of the laser of greater than 0 , 7, in particular greater than 0.8 to a value less than 0.2, in particular less than 0.1 changes. 12th are provided with this and are welded together by means of the laser. 9. The method according to any one of claims 1 to 8, characterized in that the valve base (11) is welded to the hose piece (1) from the same side as the welding of the overlapping areas of the first end section (2) and the second end section (3) of the hose piece. 10. The method according to any one of claims 1 to 9, characterized in that the tube piece (1) is cut off from a longer tube before it is provided, the absorbent material already in or on a base material of the län- geren hose is or is applied. 11. The method according to any one of claims 1 to 10, characterized in that the hose piece (1) is a thermoplastic elastomer, in particular TPU, TPE-A, TPE-E, TPE-O, TPE-S, TPE-U, TPE-V or a non-thermoplastic plastic, for example a silicone elastomer, in particular an LSR (Liquid Silicone Rubber) material comprises or is made of at least one of these materials. 12. The method according to any one of claims 1 to 11, characterized in that the at least one absorbent material from at least partially disintegrates when heated and the absorption properties in the wavelength emitted by the laser (4) 13th stands or includes these. 13. The method according to any one of claims 1 to 12, characterized in that the at least one absorbent material is an organic solvent such as acetone, etha- nol or methyl ethyl ketone (MEK) and organic color pigments. 14. Tube for a vehicle tire, characterized in that in an overlapping area of the first and the second end section (2, 3) measured normal to a lateral surface of the tube, it has an absorption coefficient in a wavelength range between 900-1200 nm of less than 0.3, especially less than 0.2, particularly preferably less than 0.1. 14th