Cross lapper

In a camel back cross lapper, a fiber web to be layered to form a fleece is guided from an infeed zone until its discharge in a layering zone in sandwiched manner between two transport belts extending over the arms of the cross lapper. The transport belts are extended over a layering zone on an output conveyor to cover the web freshly deposited onto the output conveyor to avoid the web from being affected by harmful aerodynamic effects created by the movement of the layering arm of the cross lapper. In an embodiment, a web buffer is combined with the cross lapper such manner that the transport belts extend through web buffer.

RELATED APPLICATION

This application claims the benefit of EP 04 008 051.7, filed on Apr. 2, 2004, the contents of which are incorporated herein.

FIELD OF THE INVENTION

This invention is related to the field of producing non-woven fabric or fleece made from fiber material. More particularly, the invention relates to machinery known as a cross lapper.

BACKGROUND OF THE INVENTION

When laying a fiber web (hereinafter referred to as web) onto an output conveyor, the laying arm of the cross lapper performs a pivoting movement, wherein its lower, free end moves in close distance over the output conveyor transversely to the transport direction of the latter. If the upper end of the laying arm is pivotally attached on a pivotally mounted supply arm, the supply arm also performs a pivoting movement. A cross lapper of this type, also referred to as a camel back cross lapper, is generally known and, for instance, is described in the book “Vliesstoffe”, Verlag Wiley-VCH, Weinheim, 2000 (page 160).

In known camel back cross lappers, the lower end of the laying arm is coupled to a carriage which is movably guided on rails transversely to the transport direction of the output conveyor. The carriage is connected to a drive means so that by the aid of this drive means, the pivoting movement of the laying arm, and possibly of the supply arm, is carried out.

The speed at which the web is discharged by the laying arm of the cross lapper may be more than 200 m/mm, but speeds in the range of 300 m/mm are desirable. The free end of the laying arm must therefore move correspondingly fast over the output conveyor to prevent disturbing the material and the creation of folds in the layered web. These high speeds lead to problems caused by aerodynamic effects. A web section layered by the laying arm may lift off its base and start fluttering under the influence of aerodynamic pull. One approach to alleviate this effect has been to provide a garnished pressure roller which felts the fibers of the freshly layered fiber web with the fibers of the web layers already layered arranged underneath. Since a laying arm usually discharges fiber web in both of its movement directions, two such pressure rollers may be mounted at the laying arm, increasing the weight of the laying arm accordingly. Further, the effect caused by such pressure rollers is relatively moderate.

OBJECTS OF THE INVENTION

It is an object of the invention to provide improved fleece laying apparatus which overcomes some of the problems and shortcomings of the prior art, including those referred to above.

Another object of the invention to provide a cross lapper capable of working at a relatively high laying speed.

Another object of the invention is to provide a cross lapper which holds the fiber web along all essentially all of its path through the cross lapper.

Another object of the invention is to provide a cross lapper which improves the quality of the fleece material produced therein.

Still another object of the invention is to provide a cross lapper which eliminates aerodynamic effects on the product manufactured.

How these and other objects are accomplished will become apparent from the following descriptions and the drawings.

SUMMARY OF THE INVENTION

The apparatus of this invention is a cross lapper for manufacturing a fiber fleece from a fiber web. The apparatus comprises: (1) a supply arm having lower and upper ends and pivotably mounted at its lower end around a stationary lower pivot axis; (2) a downwardly extending laying arm having upper and lower ends and pivotably supported at its upper end on the supply-arm upper end around an upper pivot axis parallel to the lower pivot axis, the laying-arm lower end being movable in a substantially straight path; (3) an endless output conveyor extending substantially parallel to the pivot axes and having a laying zone below the path of the laying-arm lower end; (4) two reversing rollers supported on a common carriage that is disposed below the output conveyor and is movable transversely thereto; (5) two endless transport belts juxtaposed for clamping and transporting the fiber to be layered and guided along the supply and arms for receiving a fiber web at an infeed zone and for laying the fiber web in the laying zone on the output conveyor under pivoting movement of the supply and laying arms, the juxtaposed belts forming a discharge nip at the laying-arm lower end, the belts extending beyond the nip in opposite directions transversely across the laying zone in proximity to the output conveyor, the belts being separately guided to the reversing rollers, back to the laying-arm lower end, and from there along the laying and supply arms to the infeed zone; and (6) drive apparatus for moving the belts, pivoting the supply and laying arms, and moving the output conveyor.

Preferred embodiments of the inventive cross lapper further include a pair of discharge nip rollers supported on the laying-arm lower end, and the transport belts each pass over one of the nip rollers.

In another embodiment of the inventive cross lapper, the laying-arm lower end and the carriage are connected to one another and to the drive apparatus by one of a traction rope, a toothed belt or a chain for pivoting movement of the laying and supply arms.

In a preferred embodiment, the inventive cross lapper also includes a pair of discharge nip rollers supported on the laying-arm lower end, and the transport belts each pass over one of the nip rollers.

In another preferred embodiment, the cross lapper further includes a pivot frame pivotably coupled to the laying lower end around an axis between and parallel to the nip rollers. The pivot frame is adapted to pivot such that the nip roller which is forward in the movement direction of the laying arm lower end is lifted and the other nip roller is lowered.

In a highly-preferred embodiment, the inventive cross lapper also includes web buffering apparatus disposed upstream of the supply-arm lower end, and the buffering apparatus guides the transport belts. In this embodiment, the transport belts each include feed sections and return sections. Along the feed sections, the belts, in juxtaposed fashion, transport the fiber web from a take-up site to the discharge nip, the juxtaposed belts running through a substantially U-shaped feed path portion substantially half-wrapped over a first deflecting roller. Along the return sections, the belts move from the supply arm to the take-up site guided through U-shaped return path portions oriented in directions opposite to the orientation of the U-shaped feed path portion, each belt half-wrapping one of second and third deflecting rollers, respectively. The web buffering apparatus includes a common mounting frame rotatably supporting the three deflecting rollers, thereby providing compensated length variation of the transport belts extending to and returning from the discharge nip as the laying lower end traverses the laying zone on the output conveyor.

In another preferred embodiment of the inventive cross lapper, the laying lower end and the carriage are connected to one another and to the drive apparatus by one of a traction rope, a toothed belt or a chain for pivoting movement of the laying and supply arms.

In other embodiments, the common mounting frame is movably held in a machine stand, and in some embodiments, the common mounting frame is movably held by a pendulum.

In some preferred embodiments of the inventive cross lapper, the common mounting frame is pivotably supported around the axis of the first deflecting roller.

In another preferred embodiment, the cross lapper also includes a tensioning roller about which the belt from one of the U-shaped return path portions is substantially half-wrapped, and the tensioning roller is biased away from the U-shape of such return path portion.

In other embodiments, the cross lapper of this invention further includes first and second independent drive rollers and a common drive roller, and the transport belts are each guided over one of the independent drive rollers and their feed sections are commonly guided over the common drive roller. In these embodiments, the common drive roller is driven at a circumferential speed that is variable with respect to the circumferential speeds of the first and second independent drive rollers, thus varying the discharge speed of the cross lapper with respect to its take-up speed.

In another embodiments, the cross lapper further includes first and second independent drive rollers, the transport belts each being guided over one of the independent drive rollers, and the first deflecting roller is also a driven roller driven at a circumferential speed that is variable with respect to the circumferential speeds of the first and second independent drive rollers; thus the discharge speed of the cross lapper is varied with respect to its take-up speed.

In another preferred embodiment, the inventive cross lapper further includes two return drive rollers, and each of the return sections between the supply arm and the U-shaped return path portions wrap at least 90° around a respective one of the return drive rollers.

In highly preferred embodiments, the supply and laying arms each have guide rollers alternatingly contacting opposite sides of the juxtaposed feed sections of the transport belts.

In other highly preferred embodiments, the inventive cross lapper further includes two return drive rollers, each of the return sections between the supply arm and the U-shaped return path portions wrap at least 90° around a respective one of the return drive rollers.

The drawings show the essential features only of the invention, and this in schematic view only, since a schematic view is sufficient for understanding the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1shows a cross lapper1with a supply arm2and a laying arm3. The supply arm2is pivotally supported on its lower end in a lower, stationary pivot axis4. laying arm3is pivotably supported in an upper pivot axis5on the upper end2U of supply arm2. The lower (free) end3L of laying arm3is movably guided above an output conveyor6which has a transport direction which extends in parallel to pivot axes4and5. Lower end3L of the laying arm3is coupled to a pivot frame7which is guided in rails (not shown) which extend transversely across output conveyor6on both sides of a laying zone.

Traction ropes, toothed belts or chains8are attached onto pivot frame7and are guided over a plurality of deflection wheels9supported in a frame (not shown) around output conveyor6. One or a pair of wheels9, designated by reference number9a, is driven by a motor (not shown). So configured, pivot frame7can be moved back and forth transversely to output conveyor6. Both supply arm2and laying arm3, arm3being coupled with pivot frame7, each carry out pivoting movements.

Two endless transport belts10and11, transporting a fiber web (not shown) to be layered, are guided over supply arm2and laying arm3and around output conveyor6in the area of the laying zone. Transport belts10and11determine a feeding path section in which transport belts10and11are guided in parallel between a take-up site A, at which the web is supplied, and a discharge nip B at lower end3L of the laying arm3. Thus, transport belts10and11are capable of sandwiching a fiber web between them and of supporting the web. This feeding path section extends from take-up site A via a reversing roller12, a driven reversing roller13, a deflection roller14close to lower pivot axis4, over supply arm2and another deflection roller15supported at the upper pivot axis5, and up to discharge nip B at lower end3L of the laying arm3. (The apparatus shown inFIGS. 1 and 2contain numerous deflecting, reversing, and drive rollers which will be specified primarily by reference number only and not by differentiating names.) Discharge nip B comprises two deflecting rollers16and17which are supported on pivot frame7at which lower end3L of laying arm3is articulated.

Starting at discharge nip B, the paths of transport belts10and11separate. In the example shown inFIG. 1, web transport belt10extends transversely over output conveyor6and two deflecting rollers18up to a reversing roller19. Roller19is supported in a lower carriage20, which is positioned below output conveyor6. Carriage20can be moved on rails (not shown) transverse to output conveyor6. Reversing roller19reverses the direction of transport belt10. Belt10then runs over deflecting rollers21back to lower end3L of the laying arm3. At this point, belt10passes over another deflecting roller22and moves to a deflecting roller23located above upper pivot axis5. Belt10then moves along supply arm2to a deflecting roller24, a drive roller25, two further reversing rollers26and27, and a drive roller28located in the area of take-up site A. In this manner, the running path of web transport belt10is completed.

Web transport belt11runs from discharge nip B at lower end3L of laying arm3via deflecting rollers18and below output conveyor6to a reversing roller29. From reversing roller29, belt11runs back via deflecting rollers21A to a deflecting roller30mounted close to lower end3L of laying arm3, along laying arm3to a deflecting roller31located below upper pivot axis5, along supply arm2and over a deflecting roller42arranged close to lower pivot axis4to a drive roller32. Belt11then moves over a pair of reversing rollers33and34to a drive roller35located in the region of take-up site A. In this manner, the path of web transport belt11is completed.

FIG. 1shows the cross lapper with supply arm2and laying arm3in a retracted position. Pivot frame7, supporting deflecting rollers16and17at discharge nip B, is located inFIG. 1on the left side of output conveyor6. In this situation, lower carriage20supporting reversing rollers19and29is located on the right, underneath the output conveyor6. ComparingFIG. 1toFIG. 2, in which laying arm2and supply arm3are extended, it can be seen that by a displacement of pivot frame7to the right, lower carriage20is moved to the left by the same displacement. Corresponding to the additional length of transport belt10moved onto the upper side of the laying zone caused by this movement, lower carriage20has moved to the left, and at the same time provided a corresponding length of transport belt11, which is supported by the coupling of traction ropes, toothed belts or chains8to the lower carriage20.

When moving lower end3L of laying arm3from the position shown inFIG. 1into the position shown inFIG. 2, deflecting roller16supported on pivot frame7is rolling on web transport belt11layered by roller16if the speed at which web transport belt10is driven by its drive roller32is as high as the movement speed of pivot frame7. Since the fiber web is discharged at this speed from discharge nip B, the section of web transport belt11resting on the freshly layered web does not have a relative speed with respect to the web (except for the movement of output conveyor6transverse to the laying direction of laying arm3). During this movement, transport belt10has a speed relative to speed at take-up site A zone which consists of the sum of the running speed of pivot frame7and the supply speed of transport belt10. The same applies to transport belts10and11for movement of pivot frame7in the reverse direction. Practice has shown that this relative speed between the layered fleece and transport belts10and11covering the layered fleece does not lead to problems. As mentioned above, pivot frame7is pivoted with respect to laying arm3around a horizontal axis, so that the deflecting roller (16or17) which is in front in the moving direction, is slightly lifted.

The section located between take-up site A and an infeed zone C at the lower end of supply arm2of the structure shown forms web buffering apparatus36. On the way back from discharge nip B to take-up site A, transport belt10, after leaving supply arm2, runs over drive roller25and from there into a substantially U-shaped return path portion the apex of which is formed by reversing roller26. Belt10continues over another reversing roller27and drive roller28to take-up site A.

On its way back to take-up site A, after leaving supply arm2, transport belt11also runs over drive roller32into substantially U-shaped return path portion, the apex of which is formed by reversing roller33. From there, belt11continues over a tensioning roller34and drive roller35which is located at the take-up site A.

Reversing rollers26and33located in the path of transport belts10and11and forming the apexes of the U-shaped return path portions, are rotatably supported in a common mounting frame37on which reversing roller12is also supported and around which the web transporting sections of transport belts10and11are guided as a pair, in juxtaposed fashion. Common mounting frame37is pivotally attached at the axis of reversing roller12at a frame-shaped link38, which is only schematically shown in the drawing with a dash-dotted line. Link38is suspended like a pendulum in a pivot bearing41in machine stand M (shown in dotted line format only inFIG. 1) of the cross lapper.

Tensioning roller34is mounted on the piston of a hydraulic cylinder39attached to machine stand M. The force exerted by hydraulic cylinder39onto tensioning roller34tensions transport belt11. The tension is transferred over reversing roller33and through common mounting frame37, which acts as a two-armed lever by pivoting around the axis of reversing roller12. The tension is further transferred over reversing roller26carried by common mounting frame37to the returning section of transport belt10. Thus, both web transport belts10and11are tensioned by single hydraulic cylinder39.

On their way over the arms2and3the transport belts10and11run over several guide rollers40supported on the feeding and laying arms2and3, some of the guide rollers alternatingly contacting on the one and the other side of the paired transport belt section to prevent fluttering of the transport belts on the arms2and3.

Various operating states will now be described. As long as drive rollers13,25,28,32and35have identical circumferential speeds, common mounting frame37stays in the position shown inFIG. 1. If the circumferential speed of drive roller13becomes higher than that of the other drive rollers, drive roller13pulls common mounting frame37, through paired transport belts10and11and reversing roller12, to the left inFIG. 1, causing the length of the web transporting sections of transport belts10and11to shorten. At the same time, the length of the returning sections of transport belts10and11increases since reversing rollers26and33are also moved to the left. Positions of rollers12,26and33moved to the left are shown in dotted lines in the drawing by reference numbers12′,26′ and33′, respectively.

If, however, the drive speed of drive roller13becomes lower than the speed of the other drive rollers, common mounting frame37moves to the right (inFIG. 1) so that reversing rollers12,36and33reach the positions shown inFIG. 1by reference numbers12″,26″ and33″, respectively. Since the displacement of the reversing rollers12,26and33takes place in essentially equal amounts, transport belts10and11remain tensioned.

By the aid of the movement of common mounting frame37, the length of transport belts10and11between take-up site A and discharge nip B can be varied. Thus, it is possible to temporarily change the speed of the web discharge at discharge nip B compared to the web infeed speed at take-up site A. This change is required for cross lapper1, since the speed at which discharge nip B, i.e., the pivot frame7, moves over output conveyor6, cannot be constant, since in the area of the movement reversal points of laying arm3, its speed must be reduced by braking to zero and then accelerated in the opposite direction after the reversal of the movement. If during these braking and accelerating phases transport belts10and11continue to discharge web through discharge nip B, web thickening would result in the marginal area of the fiber web by the cross lapper, and such variations must be prevented. Thus it is necessary to vary the speed at which the web is discharged by transport belts10and11, adapting to the speed at which pivot frame7moves over output conveyor6. This variation of the discharge speed of the web from discharge nip B can be managed by suitable control of the speed of drive rollers13,25and32with respect to the speed of drive rollers28and35, wherein frame37carries out a substantially oscillating movement around pivot bearing41. This oscillating movement moves reversing rollers12,26and33between positions12′,26′ and33′ on the one hand and positions12″,26″ and33″ on the other hand, and thereby cyclically changes the buffered web volume.

The structure of web buffering apparatus36shown can also fulfill another task. For this purpose another movement component of common mounting frame37will now be explained with reference toFIGS. 1 and 2.FIG. 2shows cross lapper1with supply arm2and laying arm3in an extended position. It can readily be seen inFIG. 2that the wrapping angles of transport belts10and11on deflecting rollers15,23and31, which are arranged in arms2and3in the region of upper pivot axis5, and on deflecting rollers14,24and42, which are arranged in the region of lower pivot axis4of supply arm2, vary from the wrapping angles shown inFIG. 1. While the change of the wrapping angles of the paired web transport belt sections and also the change of the wrapping angles at deflecting rollers23and31do not have opposite influences on web transport belts10and11as far the return sections thereof are concerned, the wrapping angle of the return section of belt10on deflecting roller24inFIG. 2is smaller with respect to that inFIG. 1, whereas the wrapping angle of the returning section of belt11on deflecting roller42is greater than inFIG. 1. Such wrapping angles of web transport belts10and11therefore change in opposite directions. Transport belt10requires an increase in the running path length of its return section, while transport belt11requires a decrease in the running path length of its return section. Both can be achieved by the aid of tensioning roller34, influenced by the hydraulic cylinder39, which, inFIG. 2presses the tensioning roller34to the right, resulting in common mounting frame37being pivoted from its position shown inFIG. 1in counter-clockwise direction on link38into the position shown inFIG. 2. The length of the returning section of transport belt11is decreased, and at the same time, the length of the returning section of transport belt10is increased.

It is obvious that the movement of common mounting frame37around pivot bearing41of link38and the pivoting movement of common mounting frame37on link38around the axis of roller12reversing paired web transport belts10and11, superimpose on one another during operation, since the compensation of the speed difference of the transport belts10and11at discharge nip B and take-up site A and the compensation of the change of the roller wrapping angles in opposite directions must take place simultaneously.

As an example of a practical embodiment of the invention, the laying width is 3,500 mm. The length of arms2and3between deflecting roller31and the ends of the arms is 2,800 mm each. Transport belts2and3each have a length of 21,500 mm. The movement path of lower end3L of laying arm3of camel back cross lapper1is 4,000 mm. In the retracted condition of arms2and3(FIG. 1), arms2and3include an angle of approximately 27°, whereas in the extended position (FIG. 2), arms2and3include an angle of approximately 133°. The difference in the yielding of transport belts10and11which is caused by the change of the wrapping angles on deflecting rollers24and42(in turn caused by the different arm positions during extension), is compensated by an adjustment of approximately 20 mm on tensioning roller34by hydraulic cylinder39. Frame-like link38, at which common mounting frame37is suspended, has an effective length (pendulum length) of 1,400 mm, whereas the distance of reversing rollers26and33on the common mounting frame37from reversing roller12common to the transport belts is 520 mm each. For accommodating web buffering apparatus36, a space of approximately 2,100 mm in front of the camel back cross lapper1and a height of approximately 1,740 mm is required, including link arrangement31.

A variety of alternatives are possible and are obvious to the person skilled in the art of the present invention. For instance, reversing roller12supported on common mounting frame37may serve as a drive roller, whereas roller13may serve as an idling reversing roller. Furthermore, reversing rollers26and33supported on common mounting frame37may be drive rollers, with rollers25and32serving as idling deflecting rollers. Common mounting frame37could be pivotally supported in a movable carriage instead of being suspended on link38. Furthermore, cross lapper1could have four or more hinged arms in order to achieve a larger laying width without increasing height, such hinged arms being arranged and movable in accordion-like fashion. In such case, the movement of the arms would be coordinated with movement of the laying arm. In an arrangement of this type, transport belts10and11would be guided in pairs over all of the arms articulated to one another so that the fiber web is permanently sandwiched between two tightly contacting transport belts across its entire feeding path.

The integration of web buffering apparatus, web guidance over the supply and laying arms, and the covering of the layered web on the output conveyor by using a single pair of transport belts offers excellent advantages over the prior art not only in view of the cost of the apparatus but also in view of the quality of the product produced. The fiber web to be layered for producing a fleece is held in this integrated device in uninterrupted fashion between the web transport belts from the take-up site to the discharge nip. The fiber web is free from mechanical loads caused by free suspension, by tensioning, and by transfer from one transport belt to the other. Such freedom from mechanical loads is not available in cross lappers which work with several movable carriages. This careful and conservative treatment of the fiber web is continued after leaving the discharge nip, since the web is accompanied by one of the transport belts, namely the transport belt that covers it directly after leaving the discharge nip. The web rests on a support and is free from exposure to unfavorable aerodynamic forces as well.

While the principles of the invention have been shown and described in connection with specific embodiments, it is to be understood that such embodiments are by way of example and are not limiting.