EP1711332A1

EP1711332A1 - Ultrasound welding device

Info

Publication number: EP1711332A1
Application number: EP05700313A
Authority: EP
Inventors: Dietmar Heil; Pierre Bartholdi
Original assignee: Jentschmann AG Zuerich
Current assignee: Jentschmann AG Zuerich
Priority date: 2004-02-07
Filing date: 2005-01-17
Publication date: 2006-10-18
Also published as: WO2005075177A1; US20070158012A1

Abstract

The invention relates to an ultrasound welding device (1) which comprises a continuously operated rotating sonotrode (13). The capacity of the rotating sonotrode (13) can be controlled depending on other welding parameters in such a manner that long weld seams or pasted seams can be produced with a constant quality. The method can be used for producing awnings, tarpaulins or items of clothing.

Description

Ul Schnellall welding device

The invention relates to an ultrasonic welding device, a method for operating an ultrasonic welding device and workpieces produced by this method according to the features of claims 1, 5 and 8.

Ultrasonic welding is a joining technique in which e.g. thermoplastic or metallic workpieces are connected to one another by supplying energy in the form of ultrasound or high-frequency mechanical vibrations. A sonotrode that presses a first workpiece against a second workpiece is excited to vibrate in the ultrasonic range. By transferring the kinetic energy in the area of the interface of both workpieces, frictional heat is generated locally, which softens or melts the workpiece surfaces and connects them to one another.

Ultrasonic welding technology is used, among other things, to connect thermoplastic films or fabrics. In addition to devices for pulsed welding, in which the high-frequency energy is transferred to the workpieces to be connected in a pulsed manner by means of a stamp, there are already ultrasonic welding devices for the continuous connection of thermoplastic films known. The sonotrode is roll-shaped. The foils to be connected are continuously moved between the rotating sonotrode wheel and a change wheel rotating synchronously with the opposite direction of rotation, a weld seam being formed which holds the two foils together. To assemble larger workpieces or foils, a part of the welding device with the sonotrode and the pressure wheel ^{• can be moved} relative to the foils held stationary. Many parameters such as the material of the foils to be joined, the feed rate, the gap width between the sonotrode and the pressure wheel, the shape and size of the pressure wheel, the contact pressure of the sonotrode and the power supplied to the sonotrode influence the quality of the seam to be formed. The determination of suitable parameter constellations is much more difficult with continuously operated ultrasonic welding systems than with clocked ones. In addition, only relatively narrow weld seams have been formed so far, which were insufficient for various applications. A disadvantage of such conventional continuously operated welding systems is that fluctuations in the quality of the seams formed can occur. In particular, such seams can have weak points at which the foils are insufficiently welded to one another, or areas where the foils, for example damaged or destroyed due to excessive heat.

It is an object of the present invention to provide a continuously operable ultrasonic welding device and a method for its operation as well as workpieces which can be produced using this method.

These objects are achieved by an ultrasonic welding device and a method for operating an ultrasonic welding device and by workpieces according to the preamble of claims 1, 5 and 8.

The ultrasonic welding device according to the invention and the method according to the invention are based on the regulation of the welding power of a roller sonotrode as a function of welding parameters. They are suitable for welding or assembling tissue or foil-like workpieces using hot glue. Both coated and uncoated workpieces can be connected to each other in this way. Even if these workpieces have large dimensions and / or the joints or weld seams are very long, they can be manufactured regularly with consistent quality. They can be of uniformly high strength and / or good

Sealing properties are manufactured over the entire seam length, i.e. also in the edge areas. The pressing or Compression and simultaneous cooling of the seam after its production takes place continuously immediately after the seam formation point at the welding head. In this way, large seam lengths with uniform quality can be produced without interruption. The seam widths can be significantly larger than was previously possible, ie larger than approximately 11 mm. This opens up new applications. Connections can easily be created in a single pass for which. previously two or more successive welding processes would have been necessary. With the method and the device according to the invention, high-quality welding and bonding can be carried out inexpensively and efficiently. The processing speeds can be chosen relatively high. Different, easily exchangeable guiding devices can be attached in the area of the welding head. These take over the exact positioning and guidance of the weld metal or adhesive material when connecting, hemming or applying

Reinforcing tapes. Additionally or alternatively, the fabric can also be guided by means of guide rollers which can be lowered pneumatically, for example. When gluing, adhesive tapes, in particular double-sided, single-layer or multilayer adhesive tapes which can be activated by the action of heat and / or pressure, can also be positioned and guided by guide devices. The welding head is in a preferred embodiment arranged to be movable along a long work table, so that the length of a seam that can be produced continuously in one work step is essentially limited only by the table length. The rotational speeds of the roller sonotrode and the counter pressure roller as well as the travel speed of the welding head can be controlled independently of one another, whereby the feed ratio of the sonotrode to the counter pressure roller and welding head can be programmed. In particular, the driving speed with the

Welding speed can be synchronized. This allows welding without warping and without wave formation. The setting of the individual speeds and the surface structure of the sonotrode can influence the quality of the seam, in particular its appearance. The measurement and / or programming and / or control and / or regulation of various welding parameters such as Welding energy, vibration amplitude of the sonotrode, rotational speeds of the sonotrode and the pressure roller, driving speed of the welding head,

Gap width between sonotrode and pressure roller etc. can be done in such a way that an optimal connection is possible for different workpieces or workpiece combinations. Data or welding parameters for different applications with different materials and material qualities can be stored in a non-volatile memory and, for example, if required can be called up again under menu control or used to set the welding device. In particular, such data or welding parameters for the start phase and the end phase of the seam formation can differ from that of the phase in between. By regulating the welding performance, it can be prevented that the foils to be joined melt uncontrollably and that aggressive or toxic fumes can form. Furthermore, the welding device according to the invention has low energy consumption. Thanks to the real-time control, power peaks can be avoided. It can be prevented that changes in certain welding parameters during the welding process could lead to a change in the seam quality. The ultrasonic

Welding device can e.g. be used for welding or gluing thermoplastic films or tarpaulins or for fabrics coated with thermoplastics such as PVC. Uncoated fabrics such as The acrylic commonly used in awning production can be easily connected using hot glue. Possible applications include the production of foils, awnings, tarpaulins, clothing, etc.

The invention is described in more detail below with the aid of some figures. Show 1 shows a schematic representation of an ultrasonic welding device, FIG. 2 shows a longitudinal section of the device from FIG. 1 in the area of the sonotrode, FIG. 3 shows a basic diagram of the device, FIG. 4 shows a schematic representation of the device in the area of the pressing device.

Figure 1 shows a schematic representation of an ultrasonic welding device 1 in a first

Design. The welding device 1 comprises the following elements (non-exhaustive list):

- a long worktable 3 having a stable backbone 5 made of aluminum profiles and a horizontal ^■ work surface 7, which is divided centrally by a passage extending in the longitudinal direction of the gap 9 into two sub-panels 7a, 7b..

- An L-shaped or C-shaped support 11 which is guided on the work table 3 in the longitudinal direction on guide rails (not shown).

- A welding head with a wheel-like roller sonotrode, abbreviated sonotrode 13, which is rotatably held on a sonotrode arm 15 above the gap 9. The welding head can be guided along a guide (not shown) formed on the upper arm 11a, for example by means of of a pneumatic drive can be lowered and raised in predefinable positions or positions. If the sonotrode 13 rests on a workpiece, the contact pressure or the contact force can be detected, for example, by means of a pressure sensor. The contact pressure, designated "p" in FIG. 3, can thus be controlled and / or regulated. According to the invention, the sonotrode 13 can have a significantly larger effective width than was previously possible, for example 12 mm, 15 mm, 20 mm. An anvil in the form of a counter pressure roller or

Pressure roller 17, which is arranged axially parallel under the sonotrode 13 and serves as a stop element for the pieces of material to be connected when pressing from the opposite side by means of the sonotrode 13. (Of course, the

Anvil movable and the sonotrode position fixed). The pressure roller 17 is rotatably arranged on a carriage (not shown) which can be moved synchronously with the carrier 11 or on the forearm 11b (FIG. 2) of the carrier 11. It protrudes from below into the gap 9. The periphery or rolling surface of the pressure roller 17 preferably projects above the top of the worktop 7 or is arranged flush with it. A first drive 19 for moving or moving the carrier 11 at a speed i in

Longitudinal direction of the work table 3, a second drive 21 (Fig. 3) for rotating the roll sonotrode 13 with a surface speed v ₂ and a third drive 23 for rotating the pressure roller 17 with a surface speed v ₃ , these drives 19, 21, 23 preferably being electric servomotors. The first drive 19 can, for example, be arranged fixedly in the end region of the work table 3, an endless toothed belt connected to the carrier 11 or a similar transmission element being able to convert the rotary movement into a translational movement of the carrier 11 (not shown). The second drive 21 can, for example, be connected coaxially to the sonotrode 13 and drive it directly. It is preferably arranged in the area of the sonotrode arm 15 such that the rotary movement can be transmitted to the axis of rotation of the roller sonotrode 13 by means of a step-up or step-down. Analogously, the third drive 23 can be operatively connected to the pressure wheel 17.

- A generator electronics, abbreviated generator 25, for generating the high-frequency control power for the excitation of the sonotrode 13. The generator 25 comprises ^" a power sensor 27 or a similar detection means which outputs an analog or digital signal which corresponds to the electrical power consumption [P] of the generator 25. Corresponds to a main controller, controller 29 for short, for controlling and / or regulating the generator 25 as a function of default values or target or Command variables and measurement or control variables. In particular, the controller 29 is designed in such a way that it outputs the power P ′ delivered by the generator 25 to the sonotrode 13 or (if information is available about the efficiency of the sonotrode 13, ie about the ratio of the power delivered from the sonotrode 13 to the workpiece to von electrical power consumed by the sonotrode 13) can detect the power delivered by the sonotrode to the workpiece as a measurement or control variable. 29 also includes the control of a preferably non-volatile Speichef 30, can be stored in the different combinations of welding parameters and / or other major ^'. For example, you can combine different combinations of

Data suitable for workpieces or, alternatively, time- or position-dependent data functions or processes are saved, which favor or ensure the production of high-quality seams with uniform strength and tightness. The following are some examples of such data, with the possible range of values being given in square brackets: - Welding power P "as a guide variable as a percentage of the maximum welding power: 75% [50% ... 100%], the maximum welding power being 500W, for example , 600W, 750W, 900W or 1kW, - manipulated variable (s): amplitude A [amplitude A, pressure p] - welding speed vi: 0.1m / s [0.05m / s .., 0.35m / s] - total welding time: 5s [0. ls ... 100s] - total seam length: 4.9m [0.01m ... 20m] - U.nter- and Oberg ^'imit the scope of the respective data record (in% of the seam length saturated or saturated welding time..): 5% / 95% [0% ... N% / N% ... 100%], where N: [0 ... 100] - - Material thickness lower workpiece: 0.1mm [0.1mm ... 10mm] - Material thickness upper Workpiece*. 0.1mm [0.1mm ... 10mm] - type of adhesive tape as an intermediate layer: 0 [0, 1, 2, ... 100] (an assignment table with details such as name, layer thickness, etc. can also be saved) From such data the controller 29, for example, a suitable gap width s (Fig. 2) between

Calculate sonotrode 13 and pressure roller 17. Alternatively, this gap width s can also be specified as a storable parameter. This gap width s can serve as a limit when welding or gluing, which must not be undercut. The controller 29 monitors the gap width s or a measurable one equivalent size and can use this as an additional criterion for influencing, for example, the sonotrode amplitude or the speeds of one or more of the drives 19, 21, 23. In a particularly advantageous embodiment of the invention, a distance sensor (not shown), which can be held, for example, on the underside of the upper arm 11a or on the sonotrode arm 15, detects the distance to the upper side of the workpieces to be connected shortly before the welding point. If the material thickness changes suddenly, for example when crossing a reinforcement tape or in the area of a seam, the welding parameters, including the welding performance, can be automatically adapted or modified for this area according to a predefinable pattern.

- A power supply unit for providing the energy supply, in particular for the generator 25, the controller 29 and the electric drives 19, 21, 23 and possibly other components which are operated with electrical energy.

- An operating device 33 with operating elements 35 (for example a keyboard) and a display 37, which are preferably designed for menu-controlled operation. - Optionally, an easily mountable and removable roll holder for holding an adhesive tape roll 41.

A continuously operable pressing device 43. For example, as schematically shown in FIG. 4, this can comprise a cuboid metal body 45 with a pressing arm 4β, which, like the sonotrode 13 and the sonotrode arm 15, can be positioned pneumatically in the vertical direction and can be pressurized. Arr the lower longitudinal side of the metal body 45 are a plurality of small metal rollers 47 a lined up with a small mutual distance with good thermal conductivity on the metal body 45 freely rotatable. A guide roller is held depending 47b (not shown) with a larger diameter by means of a fastening or Spännvorrichtung the metal body 45 rotatably mounted on the two narrow sides •, said deflection rollers body 45 project beyond the MetallkÖ 47b ^'laterally and upwards. An endless belt 49 is stretched around the metal rollers 47a and the guide rollers 47b, similar to the caterpillar of a caterpillar vehicle, which preferably has good thermal conductivity properties, high mechanical stability and high flexibility, for example a steel belt. In an analogous manner, a counter-pressure band can also be arranged flush with the top of the worktop 7 on the opposite side, that is to say in the gap 9 (not shown). The pressing device 43 can additionally be cooled with compressed air or another means. Optionally one or more easily exchangeable

Guide devices 51. A holding device (not shown) for one or more guide devices 51 is provided in the area of the welding head. For hemming e.g. a guide device 51 can be used, in which an edge of the material film can be bent or folded and can be clamped between two plates fitted with rollers. The

Clamping can be done by spring force or by compressed air. A deflection device on the input side (not shown) ensures that when the carrier 11 is moved, the material edge is continuously bent over and inserted into the clamping device in a precisely positioned manner. If the hem is to be glued by means of hot glue, the guide apparatus 51 can additionally comprise a feed device (not shown) for the positionally accurate insertion of a double-sided, single-layer or multilayer adhesive tape 42 that can be activated by a dispenser roll 41 and activated by pressure and / or heat. In contrast to conventional hot-melt adhesive processes, the adhesive tape 42 can be aligned precisely before the adhesive effect begins due to the energy supply by means of the sonotrode 13. With broad

Sonotrodes 13 can be used to form hems and seams in which the adhesive is applied uniformly to the entire surface Width of the hem or seam is distributed. In addition, the heating takes place from the inside, i.e. at the boundary layers between the film or fabric and the adhesive tape. Damage or even destruction of the workpiece foils due to excessive heat input from the outside _. forth is thus preventable. The same applies analogously to feed or conveying apparatus 51 for reinforcing belts or for connecting film or fabric webs.

In a further embodiment of the invention, as e.g. can be used to manufacture smaller workpieces such as rainwear, the support 11 is stationary with the welding head, ie not movable. The weld metal can e.g. be guided manually through the welding point. Seams of any shape can also be produced in this way. The welding speed can be influenced in a similar way to a sewing machine using a foot controller or another input device. In addition, an image sensor, e.g. a sensor, such as that used in an optical mouse, register the amount and / or direction of the weld metal movement and take this measurement variable into account as a further parameter when regulating the welding power.

Claims

claims

1. Ultrasonic welding device (1) for joining tissue or film-like workpieces, comprising a continuously drivable roller sonotrode (13) and an anvil arranged opposite the roller sonotrode (13), the distance between the roller sonotrode (13) and the anvil being variable , and wherein the workpieces between the roller sonotrode (13) and the anvil can be pressed together and joined together by introducing ultrasonic vibrations via the sonotrode (13), characterized in that the welding power of the roller sonotrode (13) can be regulated by means of a control (29).

2. Ultrasonic welding device (1) according to claim 1, characterized in that the amplitude of the control signal for the sonotrode. (13) and / or the contact pressure or the contact force of the sonotrode (13) on the workpieces are manipulated variables for regulating the welding power ,

3. Ultrasonic welding device (1) according to one of claims 1 or 2, characterized in that the 'desired welding performance or the ratio of the desired welding performance to the maximum possible welding performance can be programmed or stored as target variables or reference variables.

4. Ultrasonic welding device (1) according to one of claims 1 to 3, characterized in that the sonotrode (13) has an effective width which is greater than 11 mm.

5. A method for operating an ultrasonic welding device (1) according to one of claims I to 4, characterized in that the welding power or its dependence is programmed or stored as a reference variable as a function of time or the path.

6. The method according to claim 5, characterized in that the welding power is regulated.

Method according to one of claims 5 or 6, characterized in that a double-sided adhesive strip with a hot glue is activated by energy transfer from the sonotrode (13).

Workpieces producible with the method according to one of claims 5 or 6, characterized in that they comprise a weld seam or an adhesive seam of uniform quality.

Workpieces according to claim 8, characterized in that the weld seam or adhesive seam has a width of more than 11 mm.

^'10. workpieces according to one of claims 8 or 9, characterized in that they have the shape of tarpaulins or awnings or garments.