WO2007006321A1

WO2007006321A1 - Wound metal hose for exhaust systems and method for the production thereof

Info

Publication number: WO2007006321A1
Application number: PCT/EP2005/005974
Authority: WO
Inventors: Carlo Burkhardt; Bernhard Heil
Original assignee: Witzenmann Gmbh
Priority date: 2005-06-03
Filing date: 2005-06-03
Publication date: 2007-01-18
Also published as: KR20080021117A; DE112005003508B4; KR101161426B1; DE112005003508A5

Abstract

The invention relates to a wound metal hose (1) for exhaust systems, in particular of motor vehicles. Said wound hose (1) is produced from at least one profiled metal strip (3) which is wound in the shape of a thread, and the metal strip (3) is profiled such that strip edges (2) of adjacent strip windings (3a, 3b) movably engage into one another. At least one side of the metal strip (3) is provided with a surface which has been specifically modified at the contact faces at which adjacent strip windings (3a, 3b) rest against one another such that the wound hose (1) has a maximum thermal stiffening rate of 100 %.

Description

Winding hose of metal for Abqasanlaqen and process for its preparation

The invention relates to a winding tube made of metal for exhaust systems, in particular of motor vehicles, wherein the winding tube is made of at least one profiled, helically wound metal strip and the profiling of the metal strip is designed such that strip edges of adjacent tape turns movable into each other. The invention further relates to a method for producing said winding tube.

Such corrugated hoses are usually used in exhaust pipes at the positions where moving line elements are required, which in addition to the mobility must also have a high degree of tightness and low sound radiation. This is particularly the case with motor vehicles, where movements, vibrations and vibrations are introduced into the exhaust system by the engine. The winding tubes can be used alone or as part of a complex decoupling element. A decoupling element may comprise, as further components, a bellows, a braid or a knitted fabric or a combination of these elements. It is essential that the winding tube or the Entkoppelelement containing a winding tube is arranged in the exhaust system such that the generator of movements, vibrations and vibrations (such as the engine) is decoupled from the rest of the exhaust system.

In the following, the term decoupling element both a winding tube, as well as a decoupling element, which next to the winding tube further elements such as a metal bellows or a metal mesh or -gestricke has called.

Winding hoses are made of a metal band, which is profiled in such a way and helically wound, that the band edges of adjacent tape turns interlock. At this interlocking connection of the band edges several, in itself contradictory requirements are made: For a high Tightness or damping effect is a fixed winding appropriate, ie that the band edges of adjacent Bandwindungen abut each other with high pressure. However, for the mobility of the winding tube, the adjoining band edges must move sufficiently smoothly against each other. In addition, in conventional winding tubes a heat stiffening is observed, which manifests itself in the fact that the friction between adjacent tape turns increases in use due to the effect of temperature, so that the mobility of the winding tube is reduced.

In the design of a winding tube must therefore always be considered a subsequent change in mobility due to temperature. Because of this, components are often fabricated with less friction between adjacent tape windings than would be necessary for the optimum damping effect. Often, it is not possible to design the friction in such a way that, given the different driving behavior of all end users and the associated different temperature effects, an acceptable damping of the vibrations is ensured. As a result, there are more complaints.

To meet this requirement, different solutions have been proposed:

In EP 0 527 413 of the applicant, a winding tube made of metal is described in which band-shaped inserts made of a permanently elastic material are arranged under prestressing in the intermeshing profile turns. This band-shaped insert which acts as a spacer consists for example of chromium-nickel steel and is intended on the one hand to fulfill sealing functions and, on the other hand, to reduce the friction of adjacent band windings.

However, the additional band-shaped insert complicates the production. In addition, the hose nominal width of the winding tube increases, which can lead to installation problems, especially in motor vehicles with there usually existing cramped installation conditions. Also, the winding tubes provided with an additional band-shaped insert typically have a reduced service life, since the insert can slip under prolonged alternating stress, whereby leaks and a deterioration of the mobility can be caused. In addition, the deposit makes it possible to Change the mobility of the winding tube by temperature effect does not prevent.

DE 294 07 779, which is also based on the applicant, describes a metal wound hose for exhaust systems in which the metal strip is provided with a coating at least on one side on the contact surfaces against which adjacent band bonds abut one another. This coating is applied by a coating method such as spraying, electroplating or powder coating.

The coating of the metal strip must be done before profiling and helical winding, since the contact surfaces are otherwise no longer accessible to the aforementioned coating process. This upstream process step increases the complexity of the manufacturing process and also the manufacturing costs. In addition, such coatings are generally not thermally stable and not wear resistant, so that the life of a provided with such a coating component is reduced.

It is also known to heat decoupling elements under a reducing atmosphere to remove an oxide layer on the surface of the metal strip. Again, however, a subsequent change in the coefficient of friction due to the effect of temperature can not be prevented, and moreover, this method can lead to micro-welds of adjacent band edges, so that the mobility is restricted.

The present invention is therefore based on the object to provide a winding tube and a method for producing a winding tube, wherein the winding tube on the one hand by a good tightness and on the other by a good mobility, which is not impaired in particular by heat stiffening should. Furthermore, the winding tube should be simple and inexpensive to produce and have a long service life.

These objects are achieved by a winding tube made of metal according to claim 1 and by a method for producing a winding tube made of metal according to claim 5. Advantageous embodiments of the invention According to the present invention, winding tubes can be found in the claims 2 to 4, preferred developments of the method according to the invention are laid down in the claims 5 to 16.

The method for producing the winding tube is thus characterized in that on the metal strip at least at the contact surfaces in the axially central region of the winding tube on which adjacent band windings abut each other, a targeted surface modification is performed at least on one side. This targeted surface modification is achieved by means of a heat treatment of the metal strip.

In contrast to the prior art thus no coating is made, for example by sputtering or powder coating, but the targeted surface change is effected by heat treatment. The heat treatment is carried out under an oxygen-containing atmosphere.

The use of a winding tube made of metal in exhaust systems typically leads to heating of the winding tube, since the exhaust gases generally have a much higher temperature than the ambient temperature. It is therefore essential that the targeted surface modification is carried out before installing the winding tube in the exhaust system, i. in particular before the first use of the winding tube in the exhaust system by the end user. This ensures that the winding tube according to the invention has a targeted surface change caused by heat treatment of the metal strip at least at the contact surfaces against which adjacent tape windings abut one another before heating through use and a possibly accompanying change in the surface of the metal strip takes place.

The targeted surface modification is carried out according to the invention at the contact surfaces of adjacent belt windings, which are substantially involved in a movement of the winding tube in use. Thus, the winding tube according to the invention has a modified surface on these contact surfaces. This applies in particular to the band windings, which are located in the axially middle region of the winding tube (ie not in the two axial end regions), since during a movement of the winding tube typically in the middle region substantial mobility of the winding tube is generated by mutually shifting the tape turns. Of course, it is also conceivable to produce at all contact surfaces on which adjacent band windings abut each other, at least one side of a targeted surface change. This ensures that regardless of the movement pattern in use, ie, regardless of which band windings generate the mobility of the winding tube by mutual relative movement, the mobility is generated at contact surfaces, which have a targeted surface change.

If the targeted surface modification is carried out on the metal strip before the winding tube is produced, then according to the invention the targeted surface modification is carried out at least at those regions of the metal strip which result in the above-mentioned contact surfaces in the finished wound tube.

It is important that either the entire metal strip or the essential participating in the movement of the winding tube turns are subjected to the heat treatment. Otherwise, undesirable subsequent changes in the frictional properties may occur, especially in the case of large movements occurring. The non-treated parts of the winding tube then have a much higher friction than the rest. This has the consequence that the temperature-treated area moves preferentially and the load is limited to a small part of the hose, which leads to an unfavorable wear behavior.

A targeted surface modification before installing the winding tube in the exhaust system has the advantage that only the metal strip or the winding tube or a winding tube containing decoupling element are subjected to the heat treatment and not the entire exhaust system must be handled.

Furthermore, the targeted surface modification is carried out such that the winding tube has a heat stiffening of at most 100%. In conventional winding tubes, the heat stiffening is typically in a range of 300% -500%. According to the information given by the applicant, the level of heat stiffening depends essentially on the temperature at which the heat treatment takes place the method according to the invention for the targeted modification of the surface is performed. To clarify this connection, the term "heat stiffening" and the underlying concept of loss work should first be defined:

The loss work of a decoupling element is the work that must be applied to overcome the friction when moving the decoupling element. The loss work significantly determines the damping capacity of the decoupling elements.

The loss work depends on the size of the component movement. Therefore, it is necessary to prescribe a special method for measuring the loss work, which compensates for the influence of movement by the movement of the component and thus enables the comparison of different decoupling elements.

If a decoupling next to the winding tube further essential for

Damping contributing components, such as a knitted fabric, the measurement should only be made on the winding tube to avoid influences of the other components on the measurement.

When measuring the loss work, the decoupling element is moved starting from the compression position into the extended position and back again. Subsequently, this movement is repeated, determining the force-displacement curve, i. For example, the applied force is applied against the axial path of the decoupling element. The force applied must be large enough so that the end points (i.e., the stretch and compression) are each safely reached, but not so large that individual components of the decoupling element are damaged.

The force-displacement curve as described above results in a typical hysteresis curve. The loss work is the quotient of the area within this hysteresis curve and the width of the hysteresis curve in the direction of the path axis. In other words, the loss work is the mean distance of the upper and lower boundary lines of the hysteresis curve in the force-displacement diagram.

A typical hysteresis curve is shown in FIG. Here, the extension or compression of the hose is specified on the X-axis and on the Y-axis the For a corresponding extension or compression expended force. The O mark on the X axis indicates the position in which the winding tube is neither stretched nor compressed. Starting from this position, the winding tube is now first compressed by the length Xi. For this purpose, the maximum force F- expended. After reaching the end point of the compression Y ₁ , the force F-acting in compression direction is slowly withdrawn and a force acting in the direction of stretch is built up on the winding tube, which force is increased to a maximum of F +. The winding tube is now in the end point of the extended position (X ₂ ). Subsequently, in turn, the force F + acting in the direction of stretch is withdrawn, or a force acting in the upsetting direction is built up, until the winding tube returns to the starting position, ie, it is neither stretched nor compressed. The application of the applied forces against the distance traveled by a hose end results in the hysteresis curve shown in FIG. The loss work can now be calculated as the quotient of the hatched area A whose boundary is formed by the hysteresis curve and two vertical lines with the distance Y, and the route length Y. The route length Y describes the evaluation range of the loss work. Y begins at a distance of 1 mm from the lower reversal point of the hysteresis curve (Y ₁ = 1 mm) and ends at a distance of 1 mm from the upper reversal point (Y ₂ = 1 mm).

The heat stiffening can now be defined as follows via the loss work:

First, the loss work of a decoupling element in the delivery state is measured, i. in the state in which the decoupling element was installed in the exhaust system and delivered with the exhaust gas insert for further total installation or for end use.

The decoupling element is placed in a 450 ° preheated oven where it is exposed to normal atmosphere, i. in normal ambient air and thus oxygen-containing atmosphere for 1 hour at 450 ° annealed.

Thereafter, the decoupling element is removed from the oven and slowly cooled in air at room temperature. Subsequently, the loss work of the decoupling element is measured again. If an increase in the loss of work is found, there is a heat stiffening, wherein the heat stiffening is given as a percentage increase in loss work before and after the treatment in the oven.

Cause of the heat stiffening is according to the findings of the Applicant an increase in the coefficient of friction of the surface of the metal strip, at least in the areas where adjacent tape turns of the winding tube abut each other. The coefficient of friction depends on the maximum temperature to which the metal strip has been exposed in an atmosphere containing oxygen. This dependency is shown qualitatively in FIG. 4: _starting at a minimum temperature, the friction coefficient increases with increasing temperature until a temperature of the maximum friction coefficient T _{maxR is} reached. From this temperature, the friction coefficient does not change significantly even at higher temperatures. If the decoupling element is cooled again, the friction coefficient remains at the value which corresponds to the maximum temperature reached during the treatment. According to the Applicant, this behavior is due to the fact that, depending on the temperature, different reactions take place on the surface of the metal strip, which result in different friction properties of the surface.

The heat stiffening is thus due to the fact that an increase in the coefficient of friction on the surface of the metal strip occurs due to the effect of temperature and thus the relative movement of the intermeshing band turns is made more difficult due to the higher friction of the adjacent contact surfaces.

According to the inventive method for producing the winding tube, the temperature at which the heat treatment of the metal strip is performed, therefore selected such that the friction coefficient can change ment by downstream temperature influence such as when using the decoupling only a maximum of such an amount which leads to a further heat stiffening of a maximum of 100%.

It is particularly cost-effective if the heat treatment of the metal strip is carried out under normal atmosphere, ie under normal ambient air. As a result, on the one hand, the presence of oxygen is guaranteed, on the other hand must no special gas atmosphere with appropriate aparativem expense and costs are produced.

In a further preferred embodiment, the heat treatment is carried out under an atmosphere which substantially corresponds to the atmosphere under operating conditions of the winding tube. In the case of motor vehicles, for example, this can be the corresponding composition of the typical exhaust gases conducted through the exhaust system. This ensures that the targeted surface change, which is carried out on the metal strip by the heat treatment, leads to a surface which would also result in a later temperature effect when using the decoupling element.

In order to achieve the smallest possible heat stiffening, it is advantageous if the targeted surface modification is carried out at a temperature which is at least the temperature of the maximum friction coefficient T _maxR . This ensures that no increase in the coefficient of friction occurs even by a downstream temperature effect. According to empirical knowledge of the applicant is for typical consisting of stainless steels or nickel based alloys winding tubes T _maxR at about 45O ⁰ C.

The length of time that the metal strip or the winding tube is exposed to the temperature may vary. It is essential that there is sufficient time for the chemical reaction of the hose material and the atmosphere to change the surface so that the desired frictional properties are set. For cost reasons, the shortest possible process times should be aimed at. Of course, if the particular application requires this, longer process times may also be necessary.

In an advantageous embodiment of the method according to the invention, the targeted surface modification is carried out after the profiling and winding of the metal strip, ie the finished wound tube is subjected to the heat treatment. This can be avoided, for example, that during profiling and winding of the metal strip a previously changed surface is damaged. Likewise, however, it is also conceivable to first perform the targeted surface on the original metal strip and then to manufacture the winding tube from the metal strip. If the targeted surface modification is carried out after the profiling and winding of the metal strip, it is advantageous if the winding tube is subjected to a soft annealing treatment, wherein the temperature of the soft annealing T _WG corresponds at least to the temperature of the maximum loss T _max v. This has the following background:

The loss of a winding tube and thus also a winding tube containing decoupling depends not only on the above-mentioned coefficient of friction of the surface of the metal strip, but also on the force with which adjacent tape turns are pressed together. This force is primarily given when profiling and helical winding of the metal strip. However, as a result of the effect of temperature, the metal is annealed, so that the force with which the contact surfaces are pressed together decreases the more, the higher the temperature of the soft annealing. The loss work of a winding tube as a function of the temperature therefore has an approximately bell-shaped course, as shown qualitatively in FIG. 5:

As the temperature increases, the loss work initially increases due to the increasing friction coefficient. As the temperature increases further, the soft annealing and the corresponding decrease in the force with which the contact surfaces are pressed together leads to a decrease in the loss work.

Depending on the material, the size of the contact surfaces and the originally generated contact pressure, the curve shown in FIG. 5 can have a pronounced maximum (solid line) or a plateau-shaped profile with maximum loss work (dashed line).

However, it is essential that there is a minimum temperature T _max , from which the loss work no longer increases even when the temperature rises. This temperature is essentially determined by the course of the friction coefficient, so that, to a good approximation, T _maxR ~ T _maxV

For a given loss work V, there are thus two temperatures which lead to the predetermined loss work V after a corresponding heat treatment of the metal strip according to the invention. This is shown in FIG. 6: A given loss work V corresponds to two temperatures T ₁ and T _WG on the curve, where T _{1 is} smaller T _maχV ur \ d T _WG greater than T _maxV . Thus, a heat treatment in the process according to the invention with each of the two temperatures would lead to the desired loss work. However, it is advantageous to set the desired loss work V by the higher of the two temperatures T _WG. At this temperature, the maximum friction coefficient has already been reached, since it _lies above T _maxV and thus also above the temperature of the maximum friction coefficient T _maxR . The adjustment of the desired loss work V thus takes place in that on the one hand a surface with the maximum friction coefficient is generated by means of targeted surface modification and on the other by soft annealing, the force with which the contact surfaces are pressed together, is set so that the desired loss work occurs.

The essential advantage of carrying out the method according to the invention at the temperature T _WG is that no change in the power loss occurs any more. On the other hand, if the heat treatment had been carried out at the temperature T ₁ , then the wound hose would initially have the desired loss work, but if the heat were applied at a temperature greater than T ₁ , the loss work would continue to increase and thus additional heat stiffening would occur.

Therefore, it is particularly advantageous if the calibration curve shown in FIG. 6, ie the dependence of the loss work on the temperature, is first measured on a winding tube. This can be done by starting a heat treatment at a temperature starting from a low temperature, then measuring the loss work, and then selecting a temperature higher by a small amount for the same process. By repeated successive executions can thus be determined a calibration curve for this winding tube. Based on the calibration curve, the optimum annealing temperature 7 _WG can be determined for a given loss work for identical winding tubes. Subsequently, in the production for each identical winding tube, the method according to the invention can be carried out with a heat treatment at the optimum annealing temperature determined as described.

The heat treatment can be carried out in different ways in the method according to the invention. The metal band or the finished winding tube can for example, in an oven or by induction heating. But other methods are possible.

It is particularly advantageous if the heat treatment is carried out by the induction annealing known per se. As a result, typically within a few seconds, the desired temperature can be achieved, so that short cycle times and thus a cost-saving manufacturing process is possible.

An embodiment of a winding tube according to the invention will be explained below with reference to the drawings. Show here

1 shows a winding tube according to the invention in side view, partly in axial section,

Figure 2 shows a detail of the winding tube according to the invention from FIG

1 in the region of the interlocking band edges in axial section.

FIGS. 3 to 6 describe the course of the friction coefficient or the loss work as a function of the temperature and have already been described above.

1 shows an inventive winding tube, which is designed as Agraffschlauch 1, shown. The Agraffschlauch 1 is wound from an S-shaped profiled metal strip. The upper half of Figure 1 shows the side view of

Agraffschlauches 1, while the lower half is an axial section or an internal view of the Agraffschlauches. The exact structure of the invention Agraffschlauches can be seen from the partial enlargement of the interlocking band edges 2 of Figure 2.

This magnification shown in Figure 2 shows two adjacent band turns of the same metal strip 3, which are folded together. The S-shaped profiling of the metal strip 3 allows legs 4, 5 to be formed on the radially inner or outer side of the fold and also inside the fold inwardly folded end panels 6 and 7, respectively. By folding the terminal fold board 7 of the first band winding 3a between the terminal fold board 6 and the leg 5 of the adjacent band winding 3b is clamped. In the same way, the terminal folding board 6 of the second tape winding 3b is clamped between the terminal folding board 7 and the leg 4 of the first tape winding 3a.

The pinching now causes a force with which the contact surfaces between Falzbord 7 and leg 5, Falzbord 6 and leg 4, and between Falzbord 7 and Falzbord 6 are pressed together.

The mobility of the winding tube is achieved by a mutually shifting the first band winding 3a relative to the second band winding 3b in the direction indicated by B in Figure 2 direction. The displacement counteracts the frictional force, which depends substantially on the abovementioned pressing force on the contact surfaces and the coefficient of friction of the contact surfaces.

The winding tube according to the invention shown in Figure 1 and Figure 2 was prepared such that after profiling and helical winding of the metal strip of the winding tube was subjected to a heat treatment under normal atmosphere. The heat treatment was carried out by induction annealing at greater than 500 ^° C. to 1000 ^° C. for a duration of greater than 15 seconds to 150 seconds. As a result, the surface 8, 9 was changed over the entire surface of the metal strip 3. Thus, at the contact surfaces in each case the specifically modified surfaces of the corresponding portion of each other and the friction between the contact surfaces is - in addition to the contact force - determined by the friction coefficient of the surfaces 8, 9.

The temperature range from greater than 500 ° C to 1000 ° C, at which the heat treatment of the winding tube has been performed, on the one hand chosen so that the surfaces 8, 9 has the maximum possible friction coefficient, ie even at higher temperatures, the friction coefficient will not increase , On the other hand, the temperature is selected so that the force with which the contact surfaces are pressed against each other has decreased by soft annealing the winding tube 1 in such a way that, in conjunction with the maximum friction coefficient of the surfaces 8, 9, a desired power loss V of Winding tube is achieved. A winding tube produced by the method according to the invention thus has, on the one hand, the advantage that a heat stiffening of at most 100% occurs and, on the other hand, a desired power loss can be achieved simply by selecting the optimum annealing temperature. In addition, the heat treatment, in particular by induction annealing under normal atmosphere compared to the coating process is inexpensive and allows short cycle times.

Claims

claims

1 . Winding hose made of metal for exhaust systems, in particular of motor vehicles, wherein the winding hose is made of at least one profiled, helically wound metal band and the profiling of the metal strip is designed such that strip edges of adjacent tape turns movable into each other, characterized in that the metal strip at least at contact surfaces in the axially central region of the winding tube, adjacent to which tape turns abut each other, at least one side has a targeted surface change, that the targeted surface modification is performed such that the winding tube has a heat stiffening of 100% maximum, and that the targeted surface change by a heat treatment of the metal strip before installing the winding tube in the exhaust system under an oxygen-containing atmosphere caused targeted surface modification.

2. winding hose made of metal for exhaust systems, characterized in that the winding tube is produced by a method of claims 5 to 16.

3. winding tube made of metal according to one of the preceding claims, characterized in that the metal strip has at least at the contact surfaces on which adjacent band windings against each other, on both sides of the targeted surface change, in particular that the metal strip has substantially on the entire surface targeted surface modification.

4. winding tube made of metal according to one of the preceding claims, characterized in that the metal strip has at least on the contact surfaces in the entire region of the winding tube, adjacent to which adjacent tape turns together, at least on one side a targeted surface change.

5. A method for producing a winding tube made of metal for exhaust systems, in particular of motor vehicles, wherein at least one metal strip is profiled and helically wound so that the band edges of adjacent tape turns movable mesh, characterized in that on the metal strip at least at the contact surfaces in the axially middle Area of the winding tube to which adjacent band windings abut each other, a targeted surface modification is performed at least on one side, that the targeted surface modification is performed by a heat treatment of the metal strip, that the heat treatment is carried out under an oxygen-containing atmosphere that the heat treatment before installing the winding tube in the

Exhaust system is performed, and that by the thus carried out targeted surface modification, the winding tube has a maximum heat stiffening of 100%.

6. A method for producing a winding tube made of metal according to claim 5, characterized in that the targeted surface modification is carried out under a normal atmosphere.

7. A method for producing a winding tube made of metal according to claim 5, characterized in that the targeted surface modification is carried out under an atmosphere which substantially corresponds to the atmosphere under operating conditions of the winding tube.

8. A method for producing a winding tube made of metal according to one of claims 5 to 7, characterized in that the targeted surface modification is carried out at a temperature which is at least the temperature of the maximum friction coefficient T _{maxR of} the surface of the metal tube, in particular at least 45O ⁰ C.

9. A method for producing a winding tube made of metal according to one of claims 5 to 8, characterized in that the targeted surface modification is carried out after profiling and winding of the metal strip.

10. A method for producing a winding tube made of metal according to one of claims 5 to 8, characterized in that the targeted surface modification is performed before winding the metal strip.

1 1. A method for producing a winding tube made of metal according to at least claim 9, characterized in that the winding tube is subjected to a soft annealing, wherein the temperature of the soft annealing T _WG at least the temperature of the maximum loss T work T _maxV , in particular at least 450 ⁰ C.

12. A method for producing a winding tube made of metal according to claim

1 1, characterized in that the soft annealing is carried out substantially at a preselected annealing temperature T _WG , which essentially leads to a desired loss of work V of the winding tube.

13. A method for producing a winding tube made of metal according to claim 12, comprising the following steps: Determining a calibration curve, which represents the dependence of the loss work of the winding tube of the annealing temperature, determining the optimum annealing temperature T _WG for a given loss work V on the basis of the calibration curve - performing the method for producing the winding tube after

Claim 1 1 with the optimum annealing temperature T _WG .

14. A method for producing a winding tube made of metal according to one of

Claims 5 to 13, characterized in that the targeted surface modification is performed such that the winding tube has a heat stiffening of a maximum of 50%, in particular a maximum of 30%.

15. A method for producing a winding tube made of metal according to one of claims 5 to 14, characterized in that the heat treatment of the metal strip is carried out by induction annealing.

16. A method for producing a winding tube made of metal according to one of claims 5 to 15, characterized in that on the metal strip at least at the contact surfaces in the entire region of the winding tube, adjacent to which adjacent tape turns abut one another, at least one side a targeted surface modification is performed ,