This application claims priority based on European patent application EP 08 165 977.3 filed Oct. 7, 2008.
FIELD
The present invention pertains to a device and to a method for transferring nonwoven material from a fleece-laying machine to a consolidation device.
Fleece-laying machines for laying nonwoven material and consolidation devices installed thereafter for the nonwoven material, e.g., needle looms for needling the nonwoven material, are known.
Fleece-laying machines can be designed as camel-back fleece layers or as horizontal layers. In each case, a laying carriage moves back and forth in a fixed rhythm over an output conveyor belt. At least two web conveyor belts in the fleece-laying machine serve to transport a card web to the laying nip in the laying carriage. The card webs are fed through the laying nip and deposited on the output conveyor belt. Because of the back-and-forth movement of the laying carriage and the forward movement of the output conveyor belt, a multi-layer fleece with the various card web layers lying at an angle to each other is obtained.
To produce nonwoven material with a uniform basis weight, it is standard practice to change the speed of the output conveyor belt in synchrony with the speed of the laying carriage, so that the edges of the card webs are straight and the various layers overlap precisely. This means that the output conveyor belt is moved in cycles at variable speed, wherein, as a rule, the output conveyor belt does not move at all for short periods of the time at the points where the laying carriage reverses direction.
The nonwoven material produced by the fleece-laying machine is then transported onward for consolidation to a consolidation device, e.g., a water-jet consolidation device, or a needle loom, which normally comprise a continuous intake. At the transfer point between the output conveyor belt of the fleece-laying machine and the consolidation device, irregularities occur in the nonwoven material to be consolidated due to the different types of movement which the two machines perform.
It is an object of the present invention to create a device for the transfer of nonwoven material from a fleece-laying machine to a consolidation device, which is simple in design and which can compensate for the variable transport speeds of the nonwoven material in the fleece-laying machine, as a result of which the nonwoven material can be sent continuously to the consolidation device. Such provides for an increase in the uniformity of the consolidated nonwoven material, and further provides a corresponding method to achieve the same.
According to an aspect of the invention, the device for transferring nonwoven material from a fleece-laying machine to a consolidation device comprises an endless circulating output conveyor belt of the fleece-laying machine for accepting card webs which are laid on the output conveyor belt from above by the fleece-laying machine, the laid card webs forming the nonwoven material. The device further comprises a first drive unit for driving the output conveyor belt at a variable speed, and a second drive unit for driving the output conveyor belt at an essentially constant speed, the second drive unit being arranged, relative to the first drive unit, such that it is closer to the consolidation device. Thus, a hanging storage buffer of the output conveyor belt is formed in a section of the output conveyor belt located between the first drive unit and the second drive unit.
Such an arrangement provides controlled compensation for the differences in speed between the output conveyor belt of the fleece-laying machine and the intake of the consolidation device. This in turn leads to a further increase in the uniformity of the consolidated nonwoven material.
The output conveyor belt is preferably designed as a slatted belt with a plurality of transverse slats. This guarantees the safe transport of the nonwoven material and at the same time makes it possible for the output conveyor belt to hang down to any desired extent.
The second drive unit preferably comprises a toothed driving roller or several parallel drive gears. The first drive unit also preferably comprises a toothed driving roller or several parallel drive gears. These are usually connected directly to the output conveyor belt and are suitable for direct transmission of force.
Alternatively or in addition, the first drive unit can comprise an endless circulating transport means, which comprises an upper strand and which is connected positively or frictionally to an upper strand of the output conveyor belt. This allows the drive means to drive the output conveyor belt by acting on an area of a section of its upper strand. This leads to uniform drive behavior and to an especially reliable and precise forward movement of the output conveyor belt in the area in front of the hanging storage buffer.
An especially suitable type of connection for ensuring the drive of the output conveyor belt is provided by a positive connection. For this purpose, the output conveyor belt preferably comprises inward-projecting teeth, and the endless circulating transport means comprises outward-projecting teeth, which engage with the teeth of the output conveyor belt in the area of the upper strand.
A preferred method for transferring nonwoven material from a fleece-laying machine to a consolidation device includes the steps of:
As an alternative to the endless circulating transport means described above, which is connected frictionally or positively to the upper strand of the output conveyor belt, a section of the upper strand of the output conveyor belt can be guided over a smooth surface before arriving at the hanging storage buffer. In this case, it may be sufficient to provide only one first toothed driving roller or several parallel first drive gears to move the output conveyor belt forward, toward the hanging storage buffer.
Additional details and advantages of the present invention can be derived from the following description, which refers to the drawings.
a and 3b are enlarged schematic side views of two alternative embodiments of the area designated “X” in
The movements of laying carriage 6 and of upper carriage 18 are coordinated with each other in such a way that, while the card web is being supplied to fleece-laying machine 2 at uniform speed, it is possible for the card web to be deposited in a controlled manner onto output conveyor belt 4 without stretching or compression within fleece-laying machine 2. Thus, upper carriage 18 travels in the same direction as laying carriage 6 but on average at only half its speed. Account is also taken of the fact that laying carriage 6 must be braked to a stop and then accelerated again at the points where it reverses direction. The card web may being supplied at variable speed when, for example, a cyclically operating web drafter (not shown) is installed upstream of fleece-laying machine 2 to produce an alternating thickness in the card web for the purpose of achieving a transverse profiling of the laid nonwoven material. Such construction allows, with the help of the independently controlled movements of upper carriage 18 and lower carriage 6, buffering of the card web within fleece-laying machine 2.
According to this exemplary embodiment, three belts and output conveyor belt 4 are present in fleece-laying machine 2. Other embodiments of the invention can also be applied to any other type of fleece-laying machines, including those with two belts and one output conveyor belt. The invention is also applicable to oppositely-moving fleece-laying machines, in which upper carriage 18 and laying carriage 6 move in opposite directions, as well as to camel-back fleece layers.
Common to all fleece-laying machines 2 is that laying carriage 6 is braked to a stop at the points where it reverses direction and must then be accelerated again in the opposite direction. In modern fleece-laying machines 2, the speed of card web deposition is also reduced correspondingly during the braking and acceleration phase to avoid an increase in the thickness of the edges of the laid nonwoven material. At the same time, output conveyor belt 4 is also adapted in a controlled manner to this cycle of movements, which means that, at the times when laying carriage 6 is braked and accelerated again in the opposite direction, output conveyor belt 4 also travels at a correspondingly slower speed. This is necessary to guarantee a precise overlap of the various card web layers, including at the edges. If the output conveyor belt 4 were to continue to travel at constant speed, such precise overlapping would not be possible. The speed of output conveyor belt 4 can drop to zero in this situation. The overall result, therefore, is that the output conveyor belt 4 executes timed movements at various speeds.
In one preferred embodiment, the output conveyor belt 4 is designed as a slatted belt with a plurality of transverse slats 22 (see
First drive unit 24 is therefore responsible for driving the endless circulating output conveyor belt 4 at variable speed. In one preferred embodiment as shown, first drive unit 24 also comprises an endless circulating transport means 28, which is also suitable for carrying along a section of the upper strand of output conveyor belt 4 in the conveying direction. Endless circulating transport means 28 can be designed in any one of the various forms of a belt, which will be discussed in greater detail below with reference to
As Illustrated in
As illustrated in the preferred embodiment of
The overall design of the machine therefore makes it possible for output conveyor belt 4 to hang down in an area of the upper strand of output conveyor belt 4. Such a hanging section of output conveyor belt 4 acts as a storage buffer to compensate for the different speeds of first drive unit 24 and of second drive unit 40. Drive units 24, 40 are actuated in such a way that the speed differences cancel each other out on average, so that the sag becomes neither to large nor too small. In the example shown here, the dotted lines show the extreme case in which output conveyor belt 4 has no sag at all, whereas the dashed lines show the case in which output conveyor belt 4 sags to a certain extent. The free-hanging lower strand of output conveyor belt 4 rises and falls in correspondence with the degree to which the section of the upper strand of output conveyor belt 4 sags.
a and 3b show two preferred embodiments of the design of endless circulating transport means 28. In both cases, output conveyor belt 4 is designed as a slatted belt with transverse slats 22 and comprises inward-projecting teeth 42. The teeth 42 are preferably snapped into a textile belt 44, which preferably consists of woven polyester fabric and which, in one embodiment, is about 40 mm wide. In
In the embodiment of
In this way, a device and a method for transferring nonwoven material from a fleece-laying machine to a consolidation device are created in which the different speed curves of the output conveyor belt 4 of the fleece-laying machine 2 and of the intake of the consolidation device 40 can be easily coordinated and compensated.
Number | Date | Country | Kind |
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08165977.3 | Oct 2008 | EP | regional |