WO2000034577A1

WO2000034577A1 - Transfer means

Info

Publication number: WO2000034577A1
Application number: PCT/EP1999/008108
Authority: WO
Inventors: Wolf Gunter Stotz; Andreas Hoferer; Hans-Ulrich Banzhaf
Original assignee: Voith Paper Patent Gmbh
Priority date: 1998-12-09
Filing date: 1999-10-27
Publication date: 2000-06-15
Also published as: EP1137846B1; DE19856745A1; EP1137846A1; ATE243280T1; DE59906042D1

Abstract

The invention relates to a transfer means for transferring a threading strip or a web of material within a machine for producing and/or treating the web of material from a take-over zone to a transfer zone along the path of the material. The transfer means comprises a suction tube (33) which can be impinged upon with reduced pressure and a receiving head (1) which is connected to the suction tube (33). Said receiving head (1) has an air duct (3) which has an inlet opening (13) for the treading strip/the web of material and which is connected to the suction tube (33). The inventive transfer means is especially characterized in that at least one nozzle (15, 17, 37) is used to introduce an additional current into the air duct (3) and/or into the suction tube (33).

Description

Transfer device

description

The invention relates to a device for transferring a threading strip or a material web within a machine for producing and / or processing the material web, ^" from a takeover area to a transfer area along a web path, according to the preamble of claim 1.

Devices of the type mentioned here are known (DE 197 24 123.9). They are used to transfer a material web, for example a paper or cardboard web, from a takeover area to a transfer area along a web path. This transfer process, also known as threading, is necessary after a web break or when the machine is started up. The transfer device comprises a pick-up head which has an air duct connected to a suction hose. The threading strip or the entire material web is led out of the web path through the suction hose which can be subjected to a vacuum. It has been shown that the guidance of the threading strip / the material web in the air channel of the receiving head and in particular in the area of the inlet opening of the suction hose is in need of improvement. It is therefore an object of the invention to improve a transfer device of the type mentioned in the introduction so that, in particular, a tear-free insertion of the threading strip / the material web into the take-up head or into the suction hose can be ensured.

To achieve this object, a transfer device with the features of claim 1 is proposed. This is characterized in particular by the fact that the receiving head has at least one nozzle for introducing an additional flow into the air duct and / or into the suction hose. The additional flow can ensure that the material web or a threading strip separated therefrom is not guided too close to the walls of the air duct and is braked there. With the aid of the additional flow, a wobbling back and forth of the threading strip, also referred to as fluttering, can preferably be completely, or at least essentially avoided, so that striking of the threading strip / material web against the wall of the air duct can be reliably avoided. Finally, the additional flow, which is preferably directed essentially in the running direction of the material web, also supports the tightening of the threading strip / the material web.

In the following it is assumed, purely by way of example, that the transfer device is used to transfer a threading strip separated from a material web, for example paper, cardboard, plastic, textile web or the like. Of course, it is also possible with the aid of the transfer device to transfer a material web with its entire width from a transfer area to a transfer area.

An embodiment of the transfer device is particularly preferred, which is characterized in that the nozzle is arranged in the region of the suction opening of the air duct and is preferably connected to the surroundings of the machine. When a vacuum is applied to the suction hose, ambient air is drawn in both through the intake opening of the air duct and via the additional nozzle. The air currents generated in this way can reliably prevent both sticking of the threading strip to a wall of the air duct and fluttering of the threading strip. Since in this exemplary embodiment the additional flow is an air flow generated by the suction of the suction hose, the construction of the transfer device can be simplified and its costs can thus be reduced.

In another advantageous embodiment of the transfer device, it is provided that the nozzle used to introduce an additional flow into the air duct and / or the suction hose is arranged in the connection area of the suction hose to the receiving head. According to a development of the invention, it is provided that the nozzle, which is preferably arranged on the receiving head, is connected via a pressure hose to an overpressure device, with the aid of which a pressurized gaseous medium, preferably air, is introduced into the air duct and / or can be inserted into the suction hose. By blowing in a gas under pressure, both the amount of air and the speed of the air flow generated in this way can be influenced in a desired manner and preferably adapted to the air flow generated by sucking in the ambient air into the suction opening of the air duct. The medium jet emerging from the nozzle, which is preferably directed essentially in the web running direction, also influences the negative pressure in the region of the air duct which is upstream of the nozzle - viewed in the web running direction.

In an advantageous embodiment of the transfer device it is provided that the air speed in the area of the suction opening of the air duct is 1.2 to 4 times the current running speed of the threading strip, while the running speed in the area of the inlet opening of the suction hose is preferably 1.2 to 3 times the running speed of the Threading strip is. When setting the speed of the air flow in the air duct or in the inlet area of the suction hose, the following parameters are preferably taken into account: width of the threading strip / the material web, the surface roughness of the material web, i.e. the frictional resistance between the material web and air, and the speed of the threading strip.

Further advantageous embodiments result from the remaining subclaims. The invention is explained below with reference to the drawing. Show it:

Figure 1 is a plan view of a first embodiment of a recording head;

Figure 2 is a plan view of the embodiment of the pick-up head described with reference to Figure 1;

FIG. 3 shows a detail of an exemplary embodiment of a receiving head in the region of a suction opening of an air duct in a longitudinal section;

FIG. 4 shows a front view of an intake opening of an air duct;

FIG. 5 shows a longitudinal section through a receiving head comprising several links;

FIG. 6 shows a perspective illustration of a longitudinal section of an air duct which has a cross-sectional expansion section;

Figures each show three illustrations of an exemplary embodiment of an expansion section of the air duct and

Figure 10 shows a cross section through a recording head in three different versions. The transfer device described below can generally be used in connection with the transfer of a material web, for example paper or cardboard web, from a takeover area to a transfer area along a web path. The path of the web is defined by devices such as guide rolls, rollers and the like. With the aid of the transfer device, it is possible to transfer a material web with its entire width or only a threading strip separated from the material web. In the parts of the transfer device explained below with reference to FIGS. 1 to 10, it is assumed that they are used to transfer a threading strip.

The transfer device used within a manufacturing and / or processing machine for the material web comprises a flexible suction hose or a flexible hose made of a flexible material, which is connected to a receiving head which has an air duct with an intake opening for the threading strip. The suction hose connected to a vacuum source can be subjected to a vacuum, which can be varied, preferably. As a result, ambient air is sucked into the air duct via the suction opening in the receiving head. The air flow generated thereby serves, among other things, to guide the threading strip in the take-up head and to transport it through the suction hose.

The transfer device further comprises a guide device, not shown in the figures, with the help of which the suction hose and the receiving head can be displaced in and against the web running direction. The speed at which the pick-up head and the suction hose are displaced during a transfer process is always lower, preferably significantly lower than the running speed at which the threading strip is guided through the machine during the transfer process. For the structure and function of the guide device, reference is also made to DE 197 24 123.9, the content of which is made the subject of this description. In the following, several exemplary embodiments of the receiving head or the air duct arranged therein are explained in more detail with reference to the figures.

Figure 1 shows a section of a first embodiment of a recording head 1 in plan view. The recording head 1 comprises several articulated links, of which only the links A to K can be seen in the illustration according to FIG. 1. The receiving head 1 has an essentially S-shaped air duct 3, which is connected at one end 5 to the suction hose, which is guided outside the web path, not shown in FIG. 1, and with its other end 7 into the path of the threading strip Material web protrudes. An air duct beginning segment 9, which forms the beginning of the air duct 3, is fastened to the first link A of the receiving head 1 as seen in the direction of web travel (arrow 11). In the area of the suction opening 13 of the air duct 3, a number of slit-shaped nozzles 15 are provided, which are here in the top 14 and the bottom side of the air duct start segment 9 are introduced. The nozzles 15 penetrate the wall of the air duct 3, which preferably has a rectangular cross section. When a suction pressure is applied to the suction hose (not shown), additional air is sucked into the air duct 3 from the surroundings of the machine via the nozzles 15. By the heat generated by the intersucking of the air passage 3 additional flow an air boundary layer on the walls of the air duct 3, _^ whereby it can be ensured that the threading strip is not performed too close to the air duct walls and decelerated there arises. This supports the trouble-free guidance of the threading strip.

FIG. 2 shows a plan view of a part of the receiving head 1 described with reference to FIG. 1 in the area of its suction opening 13. The same parts are provided with the same reference numerals, so that reference is made to the description of FIG. 1. It can be seen that here only two slot-shaped nozzles 15 are introduced into the upper side 14, while in the exemplary embodiment shown in FIG. 1 five nozzles are arranged on at least the upper side 14. Preferably, at least one further slot-shaped nozzle is attached to the underside in the area of the suction opening 13 of the air duct 3.

Two further nozzles 17 are introduced into the side walls 16 of the receiving head 1 and of the air duct start segment 9, respectively, via which air from the surroundings can also be sucked into the air duct 3. The nozzles 17 are here formed by bores and therefore have a circular cross section. Fluttering of the threading strip and sticking of the threading strip to the walls of the air duct 3 can be reliably prevented by the additional air flows generated by the suction of the ambient air through the nozzles 15 and 17, which are indicated by arrows 18.

In the exemplary embodiment shown in FIG. 2, the nozzles 15 and 17 are all inclined by an angle α <60 ° with respect to the longitudinal central axis 19 of the air duct 3 shown with a broken line. In a preferred embodiment, the angle of inclination α is in a range from 30 ° to 45 °. It has been shown that in each case one nozzle on the top and bottom and the side walls of the receiving head 1 can be sufficient to guide the inlet strips drawn or introduced into the inlet opening 13 of the air channel 3, which preferably has a rectangular cross section, in the desired manner.

FIG. 3 shows a detail of a further exemplary embodiment of the receiving head 1 in a longitudinal section. It can be seen that here the nozzles 15 and 17 are arranged in the link A of the pick-up head. The nozzles 17 have a circular cross section. The air duct 3 has a rectangular cross-section in the area of its suction opening 13, the longitudinal sides of the rectangle being provided with a radius R in the mouth region of the air duct 3. Preferably, the corners of the Air duct rounded. Because there are no sharp edges, tearing of the threading strip which is sucked into / introduced into the intake opening 13 of the air duct 3 can be avoided. The rounded, trumpet-shaped contour of the air duct in its mouth region also influences the flow of the sucked-in air in the desired manner.

In the section 21 downstream of the suction opening 13, as seen in the direction of web travel (arrow 11), the air duct 3 is flared, that is to say the upper duct wall 23 and the lower duct wall 25 diverge in the direction of flow, so that the height of the air duct 3 is continuously increased becomes. In the region of the second section 27 of the air duct 3 adjoining the first section 21, a first damming element 29 is arranged on the upper duct wall 23 and a second damming element 29 'is arranged opposite one another on the lower duct wall 25, which preferably extends over the entire width of the Extend air duct 3 and reduce the free flowable cross-sectional area of the air duct 3. Starting from the location in the area of the baffle elements 29, 29 ', in which the air duct has its lowest height H ₀ , the subsequent air duct section is conical in the flow direction, that is, the upper part wall 23 and the lower part wall 25 of the air duct 3, which here are formed by surfaces of the baffle elements 29, 29 'diverge in the direction of flow. In a preferred embodiment, the maximum value of the height H _{0 of} the air duct 3 in the area of the baffle elements 29, 29 'is approximately 0, β times to 0.8 times the average height of the part of the air duct 3 downstream of the baffle elements 29, 29'. The baffle elements 29, 29 'are preferably streamlined, so that there is only a slight pressure loss.

As can be seen from FIG. 3, in the member B of the receiving head 5 there are further baffle elements 29 and 29 'which are identical in design to the baffle elements provided in the member A. Due to the conical configuration of the air duct 3 in the region of its first section 21 and the baffle elements arranged in the downstream part of the air duct, the air flow is repeatedly accelerated, as a result of which the tension on the threading strip is increased. The threading strip is thus tightened in the area of the baffle elements 29, 29 ', the fixing or guiding of the threading strip also being improved by the acceleration of the air flow in the areas mentioned.

Figure 4 shows a section of the embodiment of the receiving head 1 shown in Figure 3, namely a front view of the suction opening 13 of the air duct 3. It can be seen that in the upper duct wall 23 and the lower duct wall 25 each several in the direction of flow of air in the air duct 3 , longitudinal grooves 31, which are essentially parallel to one another and are used for the rectilinear alignment of the air flow. The longitudinal grooves 31 thus have an equal judge function. The longitudinal grooves 31 are preferably provided at all "narrow points" of the air duct 3, that is to say in the regions in which the cross-sectional area of the air duct through which the air can flow is narrowed, for example in the region of the suction opening 13 and the baffle elements 29, 29 '. The longitudinal grooves 31 have an essentially rectangular contour, which is preferably sharp-edged, so that undesirable cross currents tear off at the sharp edges.

FIG. 5 shows a detail of a further exemplary embodiment of the receiving head 1 having a plurality of links, in longitudinal section, namely the connection area of the receiving head 1 to a suction hose 33 that can be subjected to negative pressure the outer diameter of which is essentially the same as the inner diameter of the suction hose 33. The height H _{A of} the outlet opening 35 of the air duct 3, from which the ambient air sucked in via the suction opening 13 and possibly the nozzles 15 and 17 exits the air duct 3, is less than the height H _s or the diameter of the suction hose at this point, the width of the preferably rectangular air duct 3 in the region of its outlet opening 35 being approximately the same width as the suction hose. The term “approximately” is understood to mean a width of the outlet opening, which is preferably in a range from 80% to 100% of the width of the suction hose. From Figure 5 it can also be seen that the outlet opening 35 of the air duct 3 is arranged approximately in the middle of the suction hose 33.

At least one nozzle 37 is arranged in the link M of the receiving head 1 above and below the air duct 3, each of which is connected to an overpressure device 41, which is only shown with a symbol, via a pressure hose 39 indicated by a line. With the help of the overpressure device 41, which comprises, for example, a compressor, air is preferably sucked in from the surroundings of the machine, compressed and fed via the pressure hoses 39 to the nozzles 37, whose inlet openings 43 into the flow path of the air sucked in via the suction opening 13, here in Suction hose 33, on an end face 45 of the pick-up head 1, here the link M, are arranged. The air flow flowing out of the nozzles 37, which is indicated by arrows 47, is oriented essentially parallel to the air flow emerging from the outlet opening 35 of the air duct 3 and the wall 49 of the suction hose 33. In another exemplary embodiment, the nozzles 37 are connected to the surroundings, so that when the suction hose is subjected to negative pressure, the additional flow (s) is / are generated by sucking in the ambient air. It has been shown that sufficient guidance and tightening of the threading strip can also be achieved in this way. An overpressure device can optionally be dispensed with here, so that the construction of the transfer device is simplified. The speed of the air flow in the area of the suction opening of the suction hose 33 is preferably 1.2 times to 3 times the current running speed of the threading strip or the material web. The running speed of the material web can be up to 2000 m / min and above. The additional flow introduced into the suction hose 33 with the aid of the nozzles 37, the quantity and speed of which can preferably be adjusted with the aid of a control and regulating device, can be in the region in which the free flow cross section changes suddenly, that is to say in the region of the outlet opening 35 of the air duct 3, secure guidance of the threading strip can be guaranteed. The additional flow can also influence the air flow emerging from the air duct 3 in the desired manner, in particular its speed can be adjusted. A remote control can be used for this purpose, which enables the operator to influence the air flow manually.

Figure 10 shows a cross section through the recording head shown in Figure 5 along the section line AA in three different embodiments A, B and C. In the embodiment variant A (left figure), a plurality of nozzles 37 are arranged above and below the air duct 3, each having a circular Have cross-section, the cross-sections of the nozzles being different in this exemplary embodiment. Of course, the nozzles 37 can also have the same cross-sectional area. The nozzles 37 are here over the entire surface of the connector (link M) of the recording head 1 arranged distributed. In the embodiment variant B (middle illustration), two slot-shaped nozzles 37 are arranged above and below the air duct 3, which have different cross-sectional areas and run essentially parallel to the long side of the essentially rectangular air duct 3. In the embodiment variant C (right figure), a nozzle 37 is provided above and below the air duct 3, which have a circular cross-section. It is clear that the number of nozzles 37 in the receiving head can be varied, cross-sectional shapes other than those shown in FIG. 10 also being conceivable. It is important that with the aid of the nozzles 37 which can be connected directly to the surroundings and / or to the overpressure device 41, it is possible to influence the air flow flowing from the air duct 3 of the receiving head 1 into the suction hose 33 in the desired manner.

As can be seen from FIG. 5, that part of the air duct 3 which is introduced into the connecting piece (member M) of the receiving head on the suction hose has an expansion section 53, the cross section of which in the direction of flow (arrow 11) increases continuously here. A number of design variants of the extension section 53 are explained in more detail below with reference to FIGS. 6 to 9.

FIG. 6 shows a perspective illustration of a section of an exemplary embodiment of an air duct 3 in the connection area to a suction hose 33. The lower duct wall 25 and the upper one Channel wall 23 of the extension section 53 consisting of a first longitudinal section 55 and an adjoining longitudinal section 57 are inclined relative to an imaginary horizontal line in such a way that the height of the air channel 3 increases in the direction of flow. It can be seen from FIG. 6 that in the area of the first longitudinal section 55 the channel walls 23 and 25 are less inclined with respect to the imaginary horizontal than in the area of the second longitudinal section 57. It is clear that the cross-sectional area of the air channel 3 gradually in the direction of flow, in a sliding manner Transition, that is, without a sudden expansion of the channel cross section, becomes larger. At the outlet opening 35 of the air duct 3, this has its largest cross-section, whereby this cross-section is also still significantly smaller than the cross-section of the suction hose 33 in the region of the outlet opening 35. This results in a sudden expansion of the free flow cross-section in the region of the outlet opening 35 the smaller cross-sectional area of the air duct 3 into the larger cross-sectional area of the suction hose 33. The enlargement of the cross section initially leads to a reduction in the speed of the air flow. If the nozzles 37 (FIGS. 5 to 10) are connected to the overpressure device 41, this effect can be compensated for with the aid of the medium under pressure.

FIGS. 7 to 9 each show three images of an exemplary embodiment of the extension section 53, that is to say a longitudinal section of the air duct 3, the cross-sectional area of which, in particular the height, hey, increases in the direction of flow (arrow 11). All of the exemplary embodiments have in common that the extension section 53 is formed by at least one longitudinal section of the air duct 3 which widens conically in the flow direction, the inclination angle of the upper duct wall 23 and the lower duct wall 25 — depending on the embodiment of the extension section — being different. In the expansion sections 53 of the air duct 3 shown in FIGS. 7 and 9, the area in which the angle of inclination of the duct walls 23 and 25 can be changed is indicated by dashed lines. It remains to be noted that the extension section shown in FIG. 7 is of three stages, while the extension sections shown in FIGS. 8 and 9 are single-stage. The term “step” is understood here to mean a longitudinal section of the air duct with a specific cone angle.

It has been shown that the speed of the air flow in the air duct 3 and that in the suction hose 33 must be in the correct ratio to the running speed of the threading strip so that a desired guidance of the threading strip can be realized, with the following parameters in particular being taken into account: width of the threading strip / the material web and the roughness of the material web surface. It has proven to be advantageous to set the air speed at the entry of the threading strip into the take-up head to 1.2 to 4 times the running speed of the threading strip during the transfer process, while in the range of Suction hose an air speed that is 1.2 times to 3 times the running speed of the threading strip is sufficient.

In the embodiment shown in FIG. 1 of the air duct 3, which has an S-shaped course, a waist-shaped constriction 59 is provided in the web running direction, approximately in the center thereof, in which the air duct has its smallest width. It also becomes clear that the width of the air duct is essentially constant in the remaining areas. Due to this configuration of the air duct 3, a particularly safe and trouble-free guidance of the threading strip is possible. In the exemplary embodiment shown in FIG. 1, the air duct has a substantially constant height, except in the regions in which the baffle elements 29, 29 ', also referred to as bumps, are arranged.

In a preferred exemplary embodiment, the height of the air duct 3 in the area of the inlet opening 13 is less than three-quarters of the subsequent average duct height, this initial height of the air duct then widening conically in the flow direction, for example from 14 mm to 20 mm.

In another embodiment of the receiving head it is provided that the corners of the air duct having a rectangular cross section are provided with a radius, the largest radius being only half the size of the height of the air duct. Because of this configuration, the Side walls of the rectangular air duct have a shell-shaped, in particular half-shell, contour. So-called dead spaces can be avoided by this configuration of the air duct.

During the normal operation of the manufacturing and / or processing machine, that is to say when the transfer device is in the ready position, fresh suction air flows through the suction hose, which cools the hose. The air used for cooling can be introduced, for example, with the aid of a separate suction fan. In the exemplary embodiment of the receiving head, in which compressed air is introduced into the suction hose via the nozzles 37, cooling can also be achieved in this way. Of course, a separate suction fan can also be used in combination with the overpressure device 41 for cooling the transfer device.

The at least one pressure hose 39, via which the nozzles 37 are supplied with air under pressure, can be laid, for example, along the suction hose along its length and parallel to it.

The control and regulating device, by means of which the air jets introduced by means of the nozzles 37 into the path of the threading strip inside the receiving head or the suction hose can be influenced, is preferably designed such that the additional air quantity introduced into the air duct and / or into the suction hose and their Remote control speed can be changed before, during and after a transfer operation. With the help of the control and regulating device, for example, slides, clamping points or the like provided in the nozzles 15, 17 and / or 37 can be actuated, so that the freely flowable cross section of the nozzles can be specifically changed. This enables a defined setting of the speed and the size of the medium flow, preferably gas flow, in particular air flow, flowing through the respective nozzle.

The upper duct wall 23 and the lower duct wall 25 of the air duct have a conical longitudinal section 51 at their articulated abutment points of the links (see FIG. 3), which becomes smaller in cross-section in the flow direction, in order to, for example, one while the receiving head with its members adjusts to the outer contour Guide roller creates, the air flow and the threading strip guided through the pick-up head no impact point. For this it is necessary that the convexly curved part of the respective joint points in the direction of web travel. The longitudinal section 51, which is funnel-shaped in longitudinal section, thus serves for the reliable transfer of the threading strip from one link to the next link.

Claims

Expectations

1. Device for transferring a threading strip or a material web within a machine for producing and / or processing the material web, from a takeover area to a transfer area along a web path, with a suction hose that can be subjected to a vacuum and with a receiving head connected to the suction hose (33) (1), the receiving head (1) having an intake opening (13) for the threading strip / the material web and connected to the suction hose (33) and an air duct (3) and at least one nozzle (15, 17; 37) for introducing an additional flow in the air duct (3) and / or in the suction hose (33).

2. Transfer device according to claim 1, characterized in that the nozzle (15, 17) is arranged in the region of the suction opening (13) of the air duct (3).

3. Transfer device according to claim 1 or 2, characterized in that the nozzle (15, 17) is connected to the environment.

4. Transfer device according to one of the preceding claims, characterized in that the inlet opening of the nozzle (15; 17) in the air duct (3) is slit-shaped or essentially circular.

5. Transfer device according to one of the preceding claims, characterized in that the nozzle (15; 17) relative to the longitudinal central axis (19) of the air duct (3) is inclined at an angle <60 °.

6. Transfer device according to one of the preceding claims, characterized in that a plurality of nozzles (15, 17) are provided, that - seen in the web running direction - introduced into the top and / or bottom of the preferably rectangular receiving head (1) Nozzle (s) (15) in the form of a slot and that the nozzle (s) (17) introduced into the side wall (s) (16)) of the receiving head is / are essentially circular.

7. Transfer device according to one of the preceding claims, characterized in that the nozzle (37) is arranged in the connection region of the receiving head (1) to the suction hose (33).

8. Transfer device according to claim 7, characterized in that the nozzle (37) is connected via a pressure hose to an overpressure device (41), with the aid of which a pressurized medium, preferably air, into the air duct (3) and / or can be introduced into the suction hose (33).

9. Transfer device according to one of the preceding claims, characterized in that the The inlet opening of the nozzle (37) in the suction hose (33) is arranged on an end face (45) of the receiving head (1).

10. Transfer device according to one of the preceding claims 1 to 9, characterized in that the pressure and / or the amount of the medium introduced via the nozzle (15, 17; 37) into the air duct (3) and / or the suction hose (33) , preferably air, is adjustable with the aid of a control and regulating device.

11. Transfer device according to one of the preceding claims, characterized in that the height of the air duct (3) in the region of its outlet opening (35) is smaller than the height of the suction hose (33).

12. Transfer device according to one of the preceding claims, characterized in that the width of the air duct (3) in the region of its outlet opening (35) and the width of the part of the suction hose (33) adjoining the outlet opening (35) are substantially the same size.

13. Transfer device according to one of the preceding claims, characterized in that the air speed in the region of the suction opening

(13) of the air duct (3) is 1.2 times to 4 times the current running speed of the threading strip / the material web.

14. Transfer device according to one of the preceding claims, characterized in that the Air speed in the area of the suction opening of the suction hose (33) is 1.2 to 3 times the current running speed of the threading strip / the material web.

15. Transfer device according to one of the preceding claims, characterized in that the air duct (3) has a rectangular cross section at least in the region of the suction opening (13), the corners being provided with a radius.

16. Transfer device according to one of the preceding claims, characterized in that the height of the air duct (3) in the region of the suction opening (13) is less than 0.75 times the average height of the air duct (3) and that the air duct (3) - starting from the suction opening

(13) - widens conically in the direction of flow.

17. Transfer device according to claim 16, characterized in that in the conical first section (21) of the air duct (3) adjoining second section (27) at least one free-flow area of the air duct (3) tapering baffle element (29, 29 ') is arranged, which preferably extends over the entire width of the air duct (3).

18. Transfer device according to one of the preceding claims, characterized in that the maximum height of the air duct (3) in the region of the at least one damming element (29, 29 ') is approximately 0.6 times to 0.8 times the average height of the baffle element (29, 29 ') downstream of the air duct (3).

19. Transfer device according to one of the preceding claims, characterized in that in at least one wall (channel wall (23, 25)) of the air channel (3), a plurality of longitudinal grooves (31) running essentially in the direction of flow are introduced.

20. Transfer device according to one of the preceding claims, characterized in that the longitudinal grooves (31) have a rectangular, preferably sharp-edged contour.

21. Transfer device according to one of the preceding claims, characterized in that the longitudinal grooves (31) in the region of the suction opening (13) of the air duct (3) and / or the baffle element

(29; 29 ') are arranged.

22. Transfer device according to one of the preceding claims, characterized in that the

Seen in plan view, a curved, preferably S-shaped air duct (3) has a constriction, which - viewed in the direction of flow - is preferably arranged approximately in the middle of the air duct (3).

23. Transfer device according to claim 22, characterized in that the cross-sectional area of the air duct (3) is smaller at its narrowest surface than half the cross-sectional area of the suction hose (33).

24. Transfer device according to one of the preceding claims, characterized in that the air channel (3) - seen in the direction of flow - has an extension section (53) in the region in front of its outlet opening (35).

25. Transfer device according to one of the preceding claims, characterized in that the receiving head (1) comprises a plurality of articulated members (A to K; ... L), the baffle element (29, 29 '), the longitudinal grooves (31 ), the extension section (53) and / or the conical first section (21) of the air duct (3) are arranged on different links or distributed over several links.