METHOD FOR BONDING AT LEAST PARTIALLY OVERLAPPING MATERIAL LAYERS AND AUTOMATIC BONDING APPARATUS FOR PERFORMING THE METHOD

Abstract

An automatic bonding apparatus and a method for thermally induced seam bonding of weldable and/or gluable flat flexible material layers with each other which are each configured as a material web, material band and/or material piece and arranged so that they overlap at least partially wherein the bonding is performed by an electrically controlled contact heating arrangement through a heating wedge welding method. A temperature and/or a power of the heating wedge which is formed by a thin folded steel sheet blank is controlled as a function of a relative velocity between the material layers and the automatic bonding apparatus. This is performed so that a thermal energy that is transferred from the heating wedge to the material layers to be glued is kept constant. For this purpose the relative velocity is detected and the power of the heating wedge is automatically adjusted when the relative velocity changes.

Claims

1. A method for thermally induced seam bonding of weldable or gluable flat flexible material layers with each other which are each configured as a material web, a material band or a material piece and which are arranged at least partially overlapping, the method comprising the steps: using an automatic bonding apparatus; using at least one electrical contact heating arrangement that is arranged at a carrier frame of the automatic bonding apparatus with a directly electrically powered and heatable heating wedge for locally heating at least one of the material layers to a bonding temperature; using at least one contact pressure and feed roller arranged at the carrier frame and driven by an electric motor for locally compressing a heated material portion of the at least one material layer; using an electronic control for adjusting or controlling a relative velocity between the material layers and the automatic bonding apparatus and a temperature or an electrical power of a heating resistor arranged between two electrodes of the heating wedge; monitoring the relative velocity and the temperature or the electrical power of the heating wedge during a bonding process at least in predetermined time intervals; automatically adjusting the electrical power of the heating resistor upon a change of the relative velocity as a function of a determined relative velocity; increasing the electrical power of the heating resistor upon an increase of the relative velocity; and decreasing the electrical power of the heating resistor upon a decrease of the relative velocity.

2. The method according to claim 1, wherein a thermal energy that is transmitted from the heating wedge to the at least one material layer is maintained constant independently from the relative velocity.

3. The method according to claim 1, wherein the electrical power of the heating resistor is controlled by the electronic control and an actual value of the electrical power of the heating resistor is kept constant relative to a nominal value of the electrical power of the heating resistor.

4. The method according to claim 3, wherein the actual value of the electrical power of the heating resistor is determined by measuring a voltage drop at the two electrodes of the heating wedge and by measuring an electrical current through the heating resistor of the heating wedge.

5. The method according to claim 3, wherein a nominal value of the power of the heating resistor is internally separated by the electronic control into a nominal value portion that is usable for the bonding process and a nominal value portion that is not usable for the bonding process.

6. The method according to claim 5, wherein the nominal value portion that is usable for the bonding process is internally determined by the electronic control from a nominal value of an energy density of the heating wedge, the relative velocity v and a width of the heating wedge, and wherein the nominal value portion that is usable for the bonding process is a product of the nominal value of the energy density, the relative velocity, and the width of the heating wedge.

7. The method according to claim 6, wherein at least the nominal value of the power of the heating resistor or the non-useable nominal value portion of the power P of the heating resistor or the nominal value of the energy density of the heating wedge is predetermined by a user of the automatic bonding apparatus.

8. The method according to claim 1, wherein a temperature of the heating wedge is adjusted or controlled by the electronic control at least during preheating of the heating resistor before an actual bonding process.

9. The method according to claim 8, wherein a temperature dependent electrical resistance of the heating resistor is measured in order to determine the temperature of the heating wedge.

10. The method according to claim 9, wherein the temperature dependent electrical resistance of the heating resistor is determined from measuring a voltage drop at the two electrodes and from a measuring a current through the heating resistor.

11. An automatic bonding apparatus for thermally induced seam bonding of weldable or gluable flat flexible material layers with each other which are each configured as a material web, a material band or a material piece and are arranged at least partially overlapping, the automatic bonding apparatus comprising: at least one electrical contact heating arrangement that is arranged at a carrier frame of the automatic bonding apparatus and includes a directly electrically powered and heatable heating wedge for locally heating at least one material layer of the flat flexible material layers to a bonding temperature, and at least one contact pressure and feed roller arranged at the carrier frame and driven by an electric motor for locally compressing a heated material portion of the at least one material layer, wherein an electronic control is used for adjusting or controlling a relative velocity between the flat flexible material layers and the automatic bonding apparatus and a temperature or an electrical power of a heating resistor arranged between two electrodes of the heating wedge, wherein the heating resistor is formed by a folded steel sheet blank whose kink forms a heating wedge tip and whose edges that extend parallel to the kink are attached at the two electrodes, wherein the electronic control is configured according to claim 1.

12. The automatic bonding apparatus according to claim 11, wherein the steel folded sheet blank includes meandering cut windings which extend between the two electrodes.

13. The automatic bonding apparatus according to claim 11, wherein the folded steel sheet blank has a thickness between 0.1 mm and 1.0 mm and a maximum mass of 50 g.

14. The automatic bonding apparatus according to claim 11, wherein the heating resistor has identical radii with the at least one contact pressure and feed roller at least in a front portion of the heating resistor.

15. The automatic bonding apparatus according to claim 11, wherein the at least one electrical contact heating arrangement presses against the at least one contact pressure and feed roller with an adjustable force.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Subsequently the invention is described in more detail with reference to two embodiments illustrated in the drawing figure. Additional features of the invention can be derived from the subsequent description of the embodiment of the invention in combination with the claims and the appended drawing figure. The individual features of the invention can be implemented individually or in combination in various embodiments of the invention, wherein:

[0034] FIG. 1 illustrates a mobile self-propelled automatic bonding apparatus according to the invention in a schematic perspective view;

[0035] FIG. 2 illustrates a stationary automatic bonding apparatus according to the invention in a schematic perspective view; and

[0036] FIG. 3 illustrates the heating wedge of FIG. 1 or 2 in an enlarged schematic view, in side view FIG. 3A and in front view FIG. 3B.

DETAILED DESCRIPTION OF THE INVENTION

[0037] FIG. 1 illustrates an embodiment of an automatic bonding apparatus 1 according to the invention which is configured as a mobile self-propelled automatic welding apparatus 1 for overlapping edge welding of thermoplastic synthetic material webs that are not illustrated in the drawing figure. The automatic welding apparatus 1 includes a chassis 2 with a contact heating arrangement 3 arranged at the chassis for edge melting of synthetic material webs, wherein the chassis 2 has a carrier frame 4 at which plural running rollers 5 that are offset from each other and two opposite contact pressure and feed rollers 6, 6 are arranged. The lower contact pressure and feed roller 6 is fixated in place and the other upper contact pressure and feed roller 6 is pivot ably supported. The automatic welding apparatus 1 furthermore includes a drive arrangement 7 that is only partially illustrated in the drawing figure for the contact pressure and feed rollers 6, 6. The running rollers 5 are provided for support on a base, the drive and feed rollers 6, 6 are provided for passing an edge of the overlapping synthetic material webs through and the drive arrangement 7 is provided for driving the contact pressure and feed rollers 6, 6.

[0038] Furthermore a damping device 8 is arranged at the carrier frame 4 for pressing the upper contact pressure and feed roller 6 against the lower feed roller 6. The lower contact pressure and feed roller 6 is arranged at a lower longitudinal outrigger 9 which is permanently connected with the carrier frame 4. Differently therefrom the upper contact pressure and feed roller 6 is arranged at an upper longitudinal outrigger 9 which is pivotably attached at the carrier frame 4 and pivotable in a direction or against a direction of the lower longitudinal outrigger 9. The damping device 8 force loads the upper longitudinal outrigger 9 and presses it in a direction towards the lower longitudinal outrigger 9 until the two contact pressure and feed rollers 6 and 6 contact each other.

[0039] The welding apparatus 1 furthermore includes an electronic control 10 which is arranged in a housing 11 that is supported by the carrier frame 4. The electronic control 10 is provided for adjusting and/or controlling a relative velocity v between the plastic material webs and the automatic welding apparatus 1 and for adjusting and/or controlling the temperature T and/or the electrical power P of the contact heating arrangement 3.

[0040] FIG. 2 illustrates an embodiment of an automatic bonding apparatus 1 according to the invention configured as a stationary welding apparatus 1 for thermally induced seam bonding of material layers that are not illustrated in the drawing figure. The automatic welding apparatus 1 includes a stand frame 2 with a contact heating arrangement 3 arranged thereon for heating, surface melting and/or completely melting at least one of two material layers to be connected with each other in a connecting portion which is advantageously arranged proximal to an edge, wherein the stand frame 2 has a carrier frame 4 wherein two transport rollers 5 and two stand bases 15 are arranged at a bottom of the carrier frame and two contact pressure and feed rollers 6, 6 arranged opposite to each other are arranged at the carrier frame 4, wherein the contact pressure and feed rollers contact each other and one contact pressure and feed roller is supported locally fixated and the other contact pressure and feed roller is arranged movable relative thereto. The transport rollers 5 facilitate transporting the automatic welding apparatus 1 to a set up location and they carry the transport frame 4 during operation of the welding apparatus 1 together with the stand bases 15 which are configured for support on a base. The drive and feed rollers 6, 6 are provided for passing a connecting portion of the overlapping material layers through and the drive device is provided for driving the contact pressure and feed rollers 6, 6. The welding apparatus 1 furthermore includes a drive arrangement 7 for the contact pressure and feed rollers 6, 6.

[0041] Additionally a clamping device 8 that is not illustrated in the drawing figure is arranged at the support frame 4 for pressing the upper and the lower contact pressure and feed roller 6, 6 against each other. The lower contact pressure and feed roller 6 is arranged at an upward extending outrigger 9 which is permanently connected with the support frame 4 in a rigid manner. Differently therefrom the upper contact pressure and feed roller 6 is arranged at an upper downward extending outrigger 9 which is movably attached at the support frame 4. The upper outrigger 9 is pivotable and/or moveable in or against a direction of the lower outrigger 9. The damping device 8 loads the upper outrigger 9 with force and presses it in a direction towards the lower outrigger 9 until the two contact pressure and feed rollers 6 and 6 are in contact with each other.

[0042] The welding apparatus 1 furthermore includes an electronic control 10 which is arranged in a housing 11 supported by the carrier frame 4. The electronic control 10 is provided for adjusting and/or controlling the relative velocity v between the plastic material webs and the welding apparatus 1 and for adjusting and/or controlling the temperature T and the electric power P of the contact heater 3.

[0043] FIG. 3 illustrates the contact heating arrangement 3 of FIG. 1, 2 from a side and from a front. The contact heating arrangement 3 includes a directly electrically powered heatable heating wedge 12 for heating surface melting or completely melting the surface of at least one of the two material layers to be welded or glued together and two electrodes 13, 13 through which the heating wedge 12 is advantageously movably attached at the carrier frame 4. From the two electrodes 13, 13 which are threaded together in the illustrated embodiments through an insulating piece 14 conductors lead to the electronic control 10.

[0044] According to FIG. 3a the heating wedge 12 includes a heating resistor 16 which is connected with the two electrodes 13, 13 mechanically and electrically. The heating resistor 16 is formed by a folded steel sheet blank 17 whose center kink location 18 forms a heated wedge tip 19 and whose outer edges 20, 20 are attached at the electrodes 13, 13. The steel sheet blank 17 has a typical thickness between 0.1 and 1.0 mm and advantageously a maximum mass of 50 g. The heating resistor 16 is formed concave in a front portion 21 that is proximal to the heating wedge tip 19. In this portion 21 the heating resistor 16 has the same curvature radii as the two contact pressure and feed rollers 6, 6. The contact heating arrangement 3 can be pressed with an adjustable force which is imparted by a force generator that is not illustrated in the figures against the two contact pressure and feed rollers 6, 6.