Advancing material of indeterminate length – Plural material-moving means – With bight former
Reexamination Certificate
1998-11-06
2002-02-26
Mansen, Michael R. (Department: 3653)
Advancing material of indeterminate length
Plural material-moving means
With bight former
C156S265000, C156S495000, C083S038000, C242S615210
Reexamination Certificate
active
06349867
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an apparatus for transporting a continuous elongate material web along a production line or the like where the material web is subjected to various processing operations which lead to a final product. The direction of transport of the material web corresponds to the longitudinal extension of the web.
BACKGROUND OF THE INVENTION
In the manufacture of products produced from a continuous elongate material web where each product item is made on or from a discrete length of the web, problems arise in terms of production capacity in the machines in which the maximum machine or transport speed is limited due to the time required to perform an intermittent processing step or operation on the product to be formed on or from the material web. For example, in the manufacture of absorbent articles, such as baby diapers, sanitary napkins, incontinence pads and the like made up of layers of absorbent, liquid permeable and liquid impermeable material, various processing steps such as gluing, ultrasonic welding, fast mechanical processing etc. are required to be intermittently or periodically performed along the whole or less than the whole length of each product. Such processing operations or any other operations to be formed on any kind of product produced on or from an elongate material web or webs moving at a continuous speed past the processing station can result in an overall reduction in productivity because the intermittently or periodically performed processing step cannot be performed at the same speed as another processes to be carried out on the product. Therefore, the slowest processing step determines the maximum machine speed.
An apparatus for transporting an elongate flexible object such as a web wherein the speed of a section of the web is periodically varied while maintaining a constant speed of the upstream and downstream sections of the web is known from WO 95/12491 and WO 95/12539. In this known apparatus, the elongate web is continuously fed past rotating transport rollers which are oscillated parallel to the web in the direction of transport and opposite to the direction of transport thereof. During oscillation, three lengths of the elongate web are mutually parallel to each other so that a length of the web has a relative velocity which can be increased, reduced or reversed with respect to a stationary point by the oscillation of the transport rollers. This permits the performance of a processing operation on the web at a different speed than the constant speed of the web at the upstream and downstream sections of the apparatus. However, the known apparatus is relatively complicated in design and has relatively large moving masses. Additionally, the oscillating motion involves abrupt changes in direction, creating large forces which the apparatus must be designed to withstand.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide an apparatus for transporting a continuous elongate material web which is relatively simple in design but simultaneously makes it possible to easily adapt to different operating conditions.
This object is solved by an apparatus for transporting a continuous elongate material web according to the present invention.
The inventive apparatus comprises transport means arranged to transport the material web at a constant speed between a most upstream position and a most downstream position as seen along the path of transport of the material web, and at least two material web guide means arranged between the most upstream and most downstream positions along the transport path, at least one guide means being arranged upstream and at least one guide means being arranged downstream of an intermediate position between the most upstream and most downstream positions. The upstream and downstream guide means are movable relative to each other so as to impart a sinusoidal variation in speed to the material web at the intermediate position. In particular, each guide means is eccentrically rotatably mounted so as to move substantially continuously between a position in which a maximum partial length of the material web and a position in which a minimum partial length of the material web is temporarily supported by the guide means. Further, the upstream guide means moves at the same speed and in the opposite sense to the downstream guide means such that the length of the material web between the most upstream position and the most downstream position is substantially constant.
In accordance with the inventive apparatus, the production capacity is advantageously increased on account of the possibility of increasing as a whole the running or transport speed of the continuous flexible elongate material web through the apparatus while still being able to periodically or intermittently perform a processing step or operation which could not otherwise be performed at the higher constant speed of the web upstream and downstream of the inventive apparatus. This is because the inventive apparatus produces with a very simple structure a superimposed sinusoidal-like variation in velocity, i.e. relative speed of the material web with respect to a fixed point at an intermediate position along the transport path of the material through the inventive apparatus. Consequently, as compared to the constant speed, there is a change in speed of zero, increasing speed, zero, decreasing speed and back to zero at the intermediate position. By adding the sinusoidal-like variation to the constant or normal running speed by means of the inventive apparatus, the velocity through the apparatus gently changes between a value lower than the constant speed and a value higher than the constant speed. Thus, a processing step to be periodically or intermittently carried out on the material web and which requires more time than would be available at the constant speed at which the material web moves along the production line, can be performed during the low velocity period without the overall constant speed being influenced by the slower processing step. It is even possible to reduce the velocity or speed to zero if the process step requires this. Naturally, the apparatus of the present invention is suitable for implementation in a production line in which, when the products are formed along the material web without an intermediate gap between each product, only part of the length of each product along the material web is to be processed in the intermittent or periodic processing step, or, when there is a gap of an appropriately selected length, the whole length of the product can be processed. This is because the low velocity or speed period must be compensated by a high velocity or speed period of the same magnitude so as to maintain the same overall constant speed of the production line, and this compensation requires an unprocessed length along the material web.
Advantageously, the present invention can be realized in any production line requiring a relatively slow intermittent processing step. Such a slow step does not place a limitation on productivity and economy, as an overall higher line capacity can be achieved. Further, an existing production line which up to now has been limited in speed due to a slow processing step can be converted to run at a higher speed with an apparatus according to the present invention provided for the slow processing step.
An important and significant advantage of the inventive apparatus results from the fact that all main rotary parts thereof are rotated at a constant speed so that they must not be periodically accelerated. Therefore, the machine can be simpler in design and does not need to be constructed to absorb sudden increases in force caused by the periodic acceleration of masses as a result of any abrupt change in direction. The running speed of the inventive apparatus is hardly limited since the sinusoidal-like variation in speed is gentle and smooth and large masses do not have to be moved.
A particularly favourable embodiment of the inventive apparatus comprises a
Fitch Even Tabin & Flannery
Mansen Michael R.
SCA Hygiene Products AB
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