WELDING METHOD

Abstract

A method for welding a first hose end at a joint with a second hose end in a seam that extends on a circumference of the first hose end, the method comprising the steps: applying a protective layer at the joint to an inside of the first hose end; pushing the second hose end beyond the joint over the first hose end; pressing the first hose end and the second hose end together flat at the joint between two first damping jaws that are moved towards each other; welding the first hose end and the second hose end together by two first partial seams while pressed together, wherein the protective layer prevents a welding of the inside of the first hose end; releasing the first hose end and the second hose end from the two first clamping jaws after welding the two first partial seams.

Claims

1. A method for welding a first hose end at a joint with a second hose end in a seam that extends on a circumference of the first hose end, the method comprising the steps: applying a protective layer at the joint to an inside of the first hose end; pushing the second hose end beyond the joint over the first hose end; pressing the first hose end and the second hose end together fiat at the joint between two first clamping jaws that are moved towards each other; welding the first hose end and the second hose end together by two first partial seams while pressed together, wherein the protective layer prevents a welding of the inside of the first hose end; releasing the first hose end and the second hose end from the two first damping jaws after welding the two first partial seams; pressing the first hose end and the second hose end together again flat transversal to the first partial seams by two second clamping jaws; and welding the first hose end and the second hose end in two second partial seams so that the first partial seams and the second partial seams form the seam.

2. The method according to claim 1, wherein the first partial seams and the second partial seams cover different portions of the circumference.

3. The method according to claim 1, wherein the first hose end or the second hose end are made from thermoplastic polyurethane.

4. The method according to claim 1, wherein the first hose end and the second hose end are thermally welded.

5. The method according to claim 1, wherein the first clamping jaws and the second clamping jaws are transparent.

6. The method according to claim 1, wherein the protective layer is applied by a roller to the inside of the first hose end.

7. The method according to claim 1, wherein the protective layer cures before the welding.

8. The method according to claim 7, wherein the protective layer is made from a lacquer that is heat resistant up to at least 250 C. after curing.

9. A method for producing the inner tube for a vehicle wheel, the method comprising the steps: cutting a blank from an endless hose shaped extruded material; and closing the blank into a torus shape before welding the first hose end and the second hose end of the blank together according to claim to form the inner tube.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention is subsequently described based on an embodiment with reference to drawing figures, wherein:

[0021] FIG. 1 illustrates a cut through an inner tube; and

[0022] FIG. 2 illustrates a detail of the method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0023] In a method according to the invention an inner tube 1 for a non-illustrated 29 wheel of a bicycle is produced. The inner tube 1 is not illustrated to scale in FIG. 1 in a sectional view of the joint. The inner tube 1 has an outer diameter 2 of 30 mm. The wall thickness 3 of the inner tube 1 is 350 m. The inner tube 1 is fabricated endless by blow foil extrusion from thermoplastic polyurethane (TPU) on a polyester base.

[0024] The extruded material is cut into non-illustrated blanks of 2030 mm respectively precisely orthogonal to the longitudinal hose axis 4.

[0025] A first hose end 5 of the blank is opened so that the inside 6 becomes visible and easily accessible. A protective layer 7 made from a heat resistant clear lacquer (e.g. with the trade name MOTIP 04033) with a thickness of approximately 5 m is applied to the inside 6 circumferentially to a depth of 20 mm in a direction of the longitudinal hose axis 4 using a small felt roller.

[0026] The protective layer 7 wets an entire circumference of the inside 6. Thus locally limited welds are avoided which would degrade a quality of the weld seam and would even lead to not being able to separate the two inner foils from each other.

[0027] After a drying time of approximately 30 minutes during which the protective layer 7 cures the first hose end 5 is inserted into the second hose end 9 so that the two overlap by approximately 10 mm. The protective layer 7 is temperature resistant up to 800 C.

[0028] The first hose end 5 and the second hose end 9 are pressed together flat as illustrated in FIG. 2 and are initially welded together by high frequency between two first clamping jaws 10 with a length 11 of approximately 33 mm which corresponds to approximately 70% of the hose width. Simultaneously the first clamping jaws 10 emboss and print the logo of the manufacturer and technical specifications and test seals of the inner tube 1 onto the joint.

[0029] Then the inner tube 1 is erected in the portion of the cat eyes 12, pressed together again flat transversal to the first partial seams 13 and welded together again between two second clamping jaws 14 over a length 15 of approximately 19 mm which corresponds to approximately 40% of the hose width. The electrodes are made from brass and have a non-illustrated width of 5 mm in a direction of the hose longitudinal axis 4. The clamping jaws 10, 14 and thus the first partial seams 13 and the second partial seams cover 110% of the circumference in combination.

REFERENCE NUMERALS AND DESIGNATIONS

[0030] 1 inner tube

[0031] 2 outer diameter

[0032] 3 wall thickness

[0033] 4 longitudinal hose axis

[0034] 5 first hose end

[0035] 6 inside

[0036] 7 protective layer

[0037] 8 thickness

[0038] 9 second hose end

[0039] 10 first clamping jaw

[0040] 11 length

[0041] 12 cat eye

[0042] 13 first partial seam

[0043] 14 second clamping jaw

[0044] 15 length