DE10359368A1 - Ultrasonic welding of electrical conductors, e.g. stranded wires, applies pressure during welding and further ultrasonic action when relieved and measuring gap between sonotrode and counter electrode - Google Patents

Abstract

To weld conductors (32) by ultrasonics, and especially stranded wires, the wire is placed within a compression zone (30) defined by a sonotrode (16) and a counter electrode (18) and a locking section (20). When the zone is closed with the conductor, ultrasonic effects are applied by the sonotrode and pressure is applied to one or more of the zone-defining units. After welding, the pressure is relieved and the welded wire is exposed to further ultrasonics and finally the gap between the sonotrode and counter electrode is measured by a movement path monitor (38).

Description

The The invention relates to a method for welding electrical conductors by means of ultrasound, in particular for the production of passage and end nodes, the conductors being in one of at least introduced two limiting elements limited compression space and after closing the Verdichtungsraums welded being, being over a first element such as a sonotrode ultrasound and applied over a second element as a counter electrode pressurizes the conductor to be welded and wherein a characteristic size of the compression space is measured. Furthermore, the invention relates to a method for quality control of conductors welded into a compression space of an ultrasonic welding apparatus, in particular passage or end nodes, wherein the compression space at least by an ultrasound-applying first element such as a sonotrode and a second pressurizing the conductor Element as a counter electrode is limited.

At the ultrasonic welding of a node are several strands, such as copper cables, which in turn consist of several wires, placed in a compression chamber, compressed and then by ultrasound in relative vibration offset from each other. The friction between the wires leads to one another weld together the surfaces, so after welding there is a fixed node. While of compacting and welding becomes the Volume of the compression chamber reduced. This volume change can be measured by encoders and as comparison value for quality control to be used. The strength of the knot is the key quality criterion for the Process of ultrasonic welding.

Around To determine the strength of corresponding nodes, the node can by pulling or peeling destructive or not destructive measured by a kind of hardness test (splice checker) become.

From the EP 0 208 310 B1 is a method for controlling the process flow for quality control in the ultrasonic welding of workpieces known. For this purpose, a sonotrode of an ultrasonic welding device is lowered onto a resting on an anvil workpiece to activate the ultrasonic energy, wherein when placing the sonotrode on the workpiece a zero balance takes place to activate the sonotrode and to let pass through a desired deformation path.

Out SU-A 757 337 is a method of ultrasonic welding of thermoplastic materials, in which a directly at the Sonotrode mounted transducer the insertion depth of the sonotrode and thus the deformation of the workpieces during the welding process is detected. At sign change the second time derivative of the path signal is the welding process completed.

In the DE-OS 2 149 748 describes a method, an apparatus and a system for the production of connections to integrated circuits. In order to achieve improved connections, the force is controlled on a tool, but also its energization by the detected via a transducer deformation of the parts to be connected.

A Control of the welding process By means of ultrasound is known from FR-A 2 302 172, in which the speed of the sinking movement of a sonotrode during the welding process recorded, compared with preset limits and when exceeded adjustable threshold limits the power supply to the sonotrode becomes.

In WO 95/10866 discloses a method and apparatus for welding Ladders described, with the or the cross-section independent defined welding can be done, even if in arbitrary order ladder different cross sections are welded one after the other. For this purpose, after the compression of the conductor to be welded a characteristic Size of the compression chamber measured.

In order to adjust a height to be welded to the welding head and to the desired extent and to be able to adjust automatically to the desired welding cross-section, devices are known, such as these EP 0 143 936 B1 or de DE 37 19 083 C1 can be seen.

Of the The present invention is based on the problem of a method of the aforementioned type so that immediately after Make the node to be checked can, whether the weld desired Quality requirements are sufficient.

According to the invention, the problem is essentially solved in that after the welding of the conductor, the compression chamber is depressurized and ultrasound is applied to the welded conductors via the first element when pressure is applied by the second element and to closing the characteristic size of the compression space is measured.

According to the invention the exam the goodness the welding directly in the compression chamber, without the need for additional equipment. For this purpose, the invention provides that the compression chamber is relieved of pressure after welding then a short sound pulse on the weld like to give the knot. If the welding is not fixed, then the conductors or strands vibrated by the sound migrate in the direction of pressure-relieved limitation of the compression space. Thus, the limit can dodge, so due to the continue completed pressurization over the second element such as counter electrode or anvil a relatively large path change of the second element takes place. This measure of path change, that over a Weggeber Thus, it can be determined whether the weld quality requirements enough or not; because there is only a small path change, the end is closed pull that weld has the required strength.

pressure relief generally means that z. B. a side member of the compression space unlocked or relieved, so that the side element due of the pressure of the second element evading "softening" node is moved, unless this has the required strength. By dodging the limiting element, the soft dissolves Node quasi, so that the second element corresponding in direction the first element is adjusted. Thus, if not sufficient fixed node a characteristic change in the path of the second element.

By Selection of suitable parameters during the checking such as pressing force, amplitude or duration of the sound can based on the amount of the path change be distinguished whether the weld or the node is fixed or not, so desired quality requirements enough or not.

The Pressure relief of the compression chamber takes place in particular by that the compression space is limited by at least three elements and after welding at least one element to the welded conductors to the extent required unlocked or relieved. Also an adjustment of the element to open the compression space met the feature of pressure relief.

When characteristic size, the Conclusions on the goodness the welding allows is in particular a geometry value such as height, width or diagonal of the Compaction space to choose, where the geometry value is detected by a displacement sensor.

at The measuring space of the diagonals becomes apparent as the compression space closed on the periphery. In particular, however, is considered characteristic Size of the distance between the ultrasound emitting first element (sonotrode) and the pressure transmitting second element (anvil or counter electrode) selected.

With In other words, the invention relates to a method for weld together of electrical conductors by means of ultrasound, the conductors in one of at least two boundary elements limited compression space introduced and after closing welded the compression space being, being over a sonotrode is applied ultrasonically and via a counter electrode the to be welded Be charged head. Order with simple measures the goodness to be able to check the weld suggested that depressurized after welding the head of the compression chamber and then an ultrasonic pulse on the welded conductors with simultaneous pressurization applied to this and subsequently change in distance is measured by sonotrode and counter electrode. During the Pressurization of the conductor can be achieved by the pressure relief of the Compaction space such as releasing one of the delimiting elements of this the welded ladders dodge, provided that one takes place in the direction of the element Experience deformation.

• – Einbringen der zu verschweißenden Leiter in den Verdichtungsraum,
• – Kompaktieren und Verschweißen der Leiter bei gleichzeitiger Querschnittsverringerung des Verdichtungsraums,
• – Druckentlasten des Verdichtungsraums, wobei die verschweißten Leiter zwischen dem den Ultraschall abgebenden ersten Element und dem die Druckbeaufschlagung auf die verschweißten Leiter ausübenden zweiten Element verbleiben,
• – erneutes oder weiteres Applizieren von Ultraschall bei gleichzeitiger Druckbeaufschlagung auf die verschweißten Leiter und
• – Messen einer charakteristischen Größe des Verdichtungsraums und/oder Geometrie der verschweißten Leiter.

A method for quality inspection of welded conductors of the type mentioned above is characterized by the method steps:

• Inserting the conductors to be welded into the compression space,
• Compacting and welding the conductors while simultaneously reducing the cross-sectional area of the compression space,
• Depressurizing the compression space, wherein the welded conductors remain between the ultrasound emitting first element and the second element exerting the pressure on the welded conductors,
• - Again or further application of ultrasound while pressurizing the welded conductors and
• - Measuring a characteristic size of the compression space and / or geometry of the welded conductors.

there becomes dependent from the measured characteristic size of the compression space and / or the geometry of the welded conductors Goodness of welding rated.

In particular, the characteristic size of the compression space height and / or width and / or diagonals of the compression space are measured, for example by means of a displacement sensor.

The reapply the ultrasound over a period T of 10 ms ≤ T ≤ 250 ms. In this case, the reapplication of the ultrasound can be immediate to the welding process connection connect, Continue this quasi.

Around ensure that low quality welds in a normal manufacturing process can not flow, sees a highlight Further development of the invention, that when detecting quality reducer welding on the welded Head again with the pressure-relieved open compression chamber Ultrasonic while pressurizing to destroy or extensive destruction the weld is applied.

Becomes found a proper weld Thus, a targeted recompression with open compression chamber for increase the strength of the weld respectively.

Further Details, advantages and features of the invention do not arise only from the claims, the characteristics to be taken for them - alone and / or in combination - but also from the description below of the drawing to be taken preferred embodiments.

It demonstrate:

1 a schematic diagram of an ultrasonic welding arrangement,

2 a compression space of an ultrasonic welding apparatus in a first position,

3 the compression space according to 2 in a second position and

4 a further embodiment of a compression space.

In 1 In principle, an arrangement is shown, with which in particular electrical conductors are welded by means of ultrasound to end or through nodes. The assembly includes an ultrasonic welding apparatus or machine 10 , which in the usual way a converter 12 , if necessary, a booster 14 as well as a sonotrode 16 includes. The sonotrode 16 or a surface of this is a multi-part counter electrode 18 - also called anvil - and a slider 20 assigned, like this one DE 37 19 083 C1 it is apparent from the disclosure of which reference is expressly made. The sonotrode 16 or its surface, the counter electrode 18 as well as the slider 20 limit a compression chamber which can be adjusted in cross-section and which is determined on the basis of 2 - 4 is explained in more detail. In the compression space to be welded elements such as conductors are introduced.

The converter 12 is over a line 22 with a generator 24 connected, in turn, via a line 26 to a PC 28 leads, via which a control of the welding process takes place and in the welding parameters or cross section to be welded ladder entered or corresponding stored value can be retrieved.

As is clear from the 2 shows, the ultrasonic welding device 10 one from sonotrode 16 , Counter electrode 18 as well as sideshifter 20 limited compression space 30 on, in the conductor to be welded 32 be introduced. The counter electrode 18 consists of a vertically adjustable plate 34 , of which a horizontally displaceable cross slide 36 emanates. The vertically movable plate 34 is further a Weggeber 38 assigned. The movement of the vertical plate 34 , the cross slide 36 as well as the sideshifter 20 is through the double arrows 40 . 42 . 44 symbolizes.

Are the leaders 32 in the compression room 30 introduced, so first the side shifter 20 in the direction of the ladder 32 emotional. Accordingly, the cross slide 36 positioned so that it moves vertically when moving the plate 34 along the slider 20 ie along its the compression space 30 limiting area 46 can be adjusted. Lower boundary surface of the compression chamber 30 is by area 48 the sonotrode 16 educated. Opposing boundary surface is area 50 of the cross slide 36 , Remaining parallel to the boundary surface 46 extending boundary surface 52 of the compression space 30 gets off the vertical plate 34 educated.

With closed compression space 30 First, a compacting of the ladder 32 and then a welding of this, in which the sonotrode 16 is set in ultrasonic vibration. At the same time the counter electrode 18 - also called anvil - in the direction of the arrow 40 in the direction of the boundary surface 48 the sonotrode 16 adjusted, whereby a required force or pressure on the ladder 32 he follows.

After completion of the welding process, ie after making a knot 54 will after the presentation of the 3 the side shifter 20 depressurized. This can be done by unlocking or relieving the sideshift 20 done so that this in the direction of the arrow 49 through the welded knot 54 transmitted forces are moved can. Eie pressure relief can also be done by the compression chamber 30 by adjusting the sideshift 20 is opened. Then, with further pressurization on the node 54 over the counter electrode 18 or the cross slide 36 Ultrasound or a sound pulse with suitable amplitude and duration via the sonotrode 16 on the knot 54 transfer. This allows the conductors or strands of the node 54 in the direction of the slider 20 to dodge, to the extent that depends on the extent to which the node 54 has the required strength. Because of the cross slide 36 an application of force to the node 54 is given, then takes place when the conductors or strands of this movement, a vertical movement of the counter electrode 18 by the guidebook 38 measured and sent to a controller 56 is passed on. From the over the Weggeber 38 Determined path change can be via the controller 56 be determined if the node 54 the required strength and thus quality or not; because with sufficient strength of the knot 54 Only a minimal of the Weggeber 38 measured movement of the counter electrode 18 ,

Thus, for example, for a node with a cross section of 1.5 mm ^2, a path change of about 0.05 mm results if the node has the required strength. If this is not the case, for example, at a test pressure of 2 bar and a sound duration of 40 ms, a path change of 0.2 mm results, which indicates that the node does not have the strength required for further processing.

For nodes with a cross-section of, for example, 10.5 mm ² , the path change will be approximately 0.03 mm if the required strength is present. For non-fixed nodes results, for example, a path change of about 0.1 mm at a test pressure of 3 bar and a sonic pulse duration of 55 ms.

According to the schematic diagram of 4 It is also possible to carry out a quality or strength check if a compression chamber is relieved of pressure, not just on one side but on multiple sides. The decisive factor is that a manufactured knot 58 between a counter electrode enabling pressurization 62 and an ultrasonic vibration applying sonotrode 60 is arranged, as this in principle the 4 can be seen. This remaining boundary surfaces of the welding node 58 surrounding compression space of side slides 64 . 66 formed during the quality inspection, so in the further Ultraschallbeaufschlagung pressure and pressure relieved or moved away sideways.

The teaching of the invention can be further extended to the effect that when it should turn out in the quality test that a node does not have the required strength, another sound effect occurs with simultaneous pressurization, whereby the node 54 flows apart and thus is destroyed, so that a consideration in a manufacturing process is no longer possible.

Also it is possible, adequately recompressed sufficiently strong nodes. This can be opened Compaction space to increase the knot strength occur, so if further ultrasonic pulses be initiated with simultaneous pressurization.

is the invention has been explained with reference to the welding of strands, this is intended to be a limitation the teaching of the invention not done. A review of Strength of on a support welded Strands are also possible, for example.

Claims (11)

A method for welding electrical conductors such as strands by means of ultrasound, in particular for the production of passage and end nodes, wherein the conductors are introduced into a limited by at least two boundary elements compression space and welded after closing the compression space, wherein applied via a first element such as a sonotrode ultrasound and via a second element such as a counter electrode, the conductors to be welded are pressurized and wherein a characteristic size of the compression chamber is measured, characterized in that after welding the conductor of the compression chamber relieved of pressure and ultrasound placed on the welded conductor and then the characteristic size is measured , Method according to claim 1, characterized in that that limits the compression space of at least three elements and after welding at least one predetermined as locked element to the welded Conductor relieved of pressure as it is unlocked. Method according to claim 1, characterized in that that a characteristic value is a geometry value like height, Width or diagonal of the compression space, in particular distance between the first and second element is selected. Method according to claim 3, characterized that the geometry value is measured by a displacement sensor. Method for quality checking of in a compression space an ultrasonic welding device welded Ladders such as strands, in particular passage or end nodes, wherein the compression space at least by an ultrasound applying first element such as a sonotrode and a pressure-imparting the conductor second element is limited as a counter electrode through the process steps: - Introduction of the conductors to be welded in the compression room, - compacting and welding the conductor with simultaneous cross-sectional reduction of the compression space, - Pressure relief the compression space, wherein the welded conductors between the Ultrasound emitting the first element and the pressurization on the welded Conduct leader second element remain, - reapplying Ultrasonic while pressurizing the welded conductors and - Measure up a characteristic size of the compression space and / or geometry of the welded conductors. Method according to claim 5, characterized in that that in dependence from the measured characteristic size of the compression space and / or the geometry of the welded Ladder kindness the welding Is evaluated. Method according to claim 5 or 6, characterized that as a characteristic size of the compression space Height and / or Width and / or diagonal of the compression space, for example by means a displacement sensor is measured. Method according to at least one of claims 1-7, characterized characterized in that the reapplication of the ultrasound via a Time T with 10 ms ≤ T ≤ 250 ms. Method according to at least one of claims 1-8, characterized characterized in that the reapplication of the ultrasound at simultaneous pressurization on the welded conductors with a pressure P with 1 bar ≤ P ≤ 4 bar. Method according to at least one of claims 1 - 9, characterized characterized in that upon detection of quality-reduced welding on the welded Ladder with open Compression chamber again ultrasound with simultaneous pressurization to destroy or extensive destruction the weld is applied. Method according to at least one of claims 1 - 10, characterized characterized in that upon detection of a proper weld on the welded Conductor with pressure-relieved compression chamber again ultrasound with simultaneous pressurization for targeted recompression of the welding is applied.