GB2129369A

GB2129369A - Method and apparatus for applying elastic strips to a continuously moving material web

Info

Publication number: GB2129369A
Application number: GB08327384A
Authority: GB
Inventors: Kurt Stemmler; Gunter Ehlscheid
Original assignee: Winkler and Duennebier Maschinefabrik und Eisengiesserei GmbH
Current assignee: Winkler and Duennebier Maschinefabrik und Eisengiesserei GmbH
Priority date: 1982-10-14
Filing date: 1983-10-13
Publication date: 1984-05-16
Also published as: GB2129369B; SE8305178D0; FR2534566A1; DE3238051A1; SE458253B; SE8305178L; FR2534566B1; IT1161514B; IT8368058A0; GB8327384D0

Abstract

By reference to an example relating to the manufacture of disposable panty napkins, a method and apparatus are described for applying rubber strips to the leg portions of the napkins. These rubber strips are intended to provide an optimum fit on the wearer's thighs. Since the consumption of rubber strips in the manufacture of panty napkins is a considerable item in the production costs, and the prior-art methods use more rubber strips than necessary for the purpose in the finished napkin, the object of the invention is to limit the length of the required rubber strips to the functional minimum. This is achieved by a method and apparatus in which predetermined lengths are first severed from the unstretched rubber strip in a continuous movement, the resulting sections are stretched, adhesive is either applied to the sections or to the napkin material, and the sections are then applied to the web of sheeting forming the outside of the napkin.

Description

SPECIFICATION Method and apparatus for applying elastic strips to a continuously moving material web This invention relates to a method and an apparatus for applying elastic strips to a continuously moving material web. Methods and apparatus of this kind are used in the manufacture of disposable garments, e.g. panty napkins and particularly involve applying elastic strips to the non-elastic leg sections of such disposable napkins in order to provide a tight fit on the wearer's legs.

Methods and apparatus for this purpose are known, for example, from German Offenlegungsschrift 26 49 948, which discloses applying elastic strips to a continuously moving web in the manufacture of disposable napkins, the individual layers of the different materials making up a napkin of this kind being drawn as endless strips from feed rolls and fed to the machine. Thus there is initially a cohesive strip of napkins which are divided up into individual items in the final operations, folded, and then fed to the automatic packing unit.

The elastic strips at the leg sections must have some tension when the napkin is worn in order to provide a sealing effect, and yet the basically nonelastic sheeting forming the outer skin of the napkin should be free of creases as far as possible. As a result of these requirements, the elastic strips may be applied either in the unstretched state to the gathered sheeting or in the stretched state to the smooth sheeting. The first option is disclosed in U.S. Patent 4 259 220 and requires an unacceptably large amount of machinery for gathering the sheeting. The second option is technically less expensive to realize and is disclosed in the invention of German Offenlegungsschrift 26 49 948.The elastic strips which are applied in pairs and endlessly to the non-elastic sheeting in the direction of passage are given the required tension before the sticking operation.

In the manufacture of panty napkins according to the prior art disclosed by German Offenlegungsschrift 26 49 948, the prestressed elastic strips are continuously applied to the endless web of still connected napkins, but are stuck to the covering sheeting only in the region of the leg sections, since it is only here that they have to be pre-stressed, since in the other areas of the napkin this would have an adverse effect.

Since the endlessly pre-stressed elastic strips extend over the entire length of an individual napkin and are not severed until the multi-layer web is divided up, those ends of the elastic strips which are now no longer tensioned, because they are not stuck to the covering sheeting, hang down to no useful purpose. These loosely hanging band ends may be an obstruction to the further production process and the consumption of elastic strips is far above that necessary functionally.

Since the consumption of elastic strips per panty napkin is a considerable cost item, the loose band ends mean that the product is made unnecessarily expensive. Another disadvantage of the method according to German Offenlegungsschrift 26 49 948 is that there is a risk that the two elastic strips to be stuck to the moving web will be applied with different prestressing in the region where they are stuck to the covering sheeting. This risk arises from the fact that the pair of rollers providing the prestressing provides the same stretch in both elastic strips but the stretching may fluctuate to varying degrees due to inhomogeneity and differences in the dimensions of one strip and another. This effect is further intensified because the prestressing is produced at the endless elastic strips and hence the differences in the stress can have a cumulative effect from one cycle to the next.This shows up another disadvantage of the method disclosed in German Offenlegungsschrift 26 49 948. The adhesive is applied intermittently to the endless elastic strips in the stressed area, the application being to the same place simultaneously on both strips. When the elastic strips are combined with the covering sheeting, however, the different tensions may cause the areas of the strips to which adhesive has been applied to be offset from one another and from the leg sections in the covering sheeting. The consequences in the end product are a poor fit of the panty napkins and the risk of malfunctioning in the packaging plant at the end of the manufacturing process. After the individual napkins have been separated from the web, and the resulting contraction of the elastic strips, offset strips result in a shift in the gathering of the area stuck to the covering sheeting.Consequently, malfunctioning may occur in the mechanical transverse and longitudinal folding of the finished napkins before they are introduced into a packing carton.

The object of the invention is to provide a method and apparatus to obviate the disadvantages of the methods and apparatus according to the prior-art, and with a considerable reduction in the consumption of elastic strip.

According to one aspect of the present invention in a method of applying elastic strips, e.g. cyclically, to a continuously moving nonelastic web of material, (a) predetermined lengths are severed from the elastic strip fed in the unstretched state, (b) the severed sections of the elastic strip are stretched to predetermined lengths, (c) adhesive is applied to the stretched sections of the elastic strips, (d) the elastic strip sections which have been provided with adhesive, and which are kept stretched, are applied to the continuously moving non-elastic material web and (e) the stretched sections of the elastic strips are held in the stretched state on the continuously moving non-elastic web of material until the adhesive has set.

According to another aspect of the present invention in a method of applying elastic strips, e.g. cyclically, to a continuously moving nonelastic web of material (a) predetermined lengths are severed from the elastic strips fed in the unstretched state, (b) the severed sections of the elastic strip are stretched to predetermined lengths, (c) adhesive is applied to those areas of the non-elastic material web which are required to be covered by the elastic strips, (d) the sections of the elastic strips, which are kept in the stretched condition, are applied to the adhesive on the continuously moving non-elastic material web and (e) the stretched sections of the elastic strips are held in the stretched state on the continuously moving non-elastic web of material until the adhesive has set.

Preferably the adhesive used is a hot-melting adhesive which is applied to the sections of elastic strips kept in the stretched condition or to those areas of the non-elastic material web which are required to be covered by the elastic strips.

According to another aspect of the present invention in apparatus for applying elastic strips to a continuously moving non-elastic web of material, a straightening unit is followed by a pair of feed rollers which draws the elastic strips into the apparatus and feeds them over a reversing roller to a cutter roller co-operating with a co-acting roller equipped with holder elements for the elastic strips, the said cutter roller being arranged to sever the unstretched elastic strips while they are held fast on the co-acting roller by their trailing ends and the leading ends of the elastic strips are engaged and stretched by the holder elements of a following stretching roller, which rotates at a higher circumferential speed, until the trailing ends are also engaged by the holder elements of the stretching roller after stretching is completed, whereafter the elastic strips are provided with adhesive by an adhesive applicator associated with the stretching roller, and are then applied to the non-elastic web of material which is trained around the combining roller at the same circumferential speed.

The invention may be carried into practice in various ways, but one specific embodiment will now be described, by way of example, with reference to the accompanying drawing which is a purely diagrammatic side elevation of a station for cyclically applying elastic strips to a continuously moving non-elastic web of sheeting in a machine for the manufacture of disposable panty napkins.

A straightening unit 3 is disposed at the inlet to the apparatus according to the invention and consists of a number of small rollers disposed seriatim. This is followed by a pair of feed rollers 4 and 5, which is in turn followed by a reversing roller 6. A severing device is disposed above the latter and consists of a cutter roller 7 co-operating with a co-acting roller 8. The latter is followed by a stretching roller 9, which is in turn followed by a combining roller 10. With the exception of the small rollers of the unit 3, the rollers referred to in the apparatus are driven rollers and rotate at the same circumferential speed within two consecutive groups. The first group comprises the rollers 4-8, the second group is the rollers 9 and 10 and rotates at a higher circumferential speed than the first group.The rollers 8-10 are provided with holder elements (not shown) which may be in the form of known mechanically or pneumatically operated gripper devices e.g.

suction bores to which vacuum is applied. An adhesive applicator 11 is associated with the roller 9 and another adhesive applicator 12 is associated with roller 10. The latter roller may be provided with a cooling means.

The elastic strips, of rectangular cross-section, lying loosely in the container 1 are drawn in pairs through the straightening unit 3 by the feed rollers 4 and 5. The object of unit 3 is to lay the strips flat and eliminate any twist therein before they enter the apparatus. By guiding the elastic strips 2 alternately above and beneath the small rollers disposed seriatim in the unit 3 they ere subjected to some tension without stretching them. From the feed rollers 4 and 5 they pass over the reversing roller 6 to the roller 8, where their leading ends are engaged by holder elements (not shown). The predetermined lengths of the strips 2 in the unstretched state are then severed by the cutter roller 7 and their trailing ends are also held on the roller 8.At the instant of severance, the leading ends of the strips 2 are released by the holder elements of the roller 8 and are engaged by the holder elements of the roller 9. Since, as already stated, the latter rotates at a higher circumferential speed than the roller 8, the severed sections of the elastic strips are now stretched between the trailing ends held on the roller 8 and the leading ends held on the roller 9.

The stretching operation is complete as soon as the trailing ends are engaged by the holder elements of the roller 9 and are released by the holder elements of the roller 8. The elastic strip sections are now situated in their predetermined stretched length on the roller 9. Adhesive is now applied to the stretched strips by the applicator 11 and the strips 2, provided with the adhesive, pass in the stretched state on to the web of material 13 trained around the combining roller 10. Here the strips are held in the stretched condition until the adhesive has set.

Alternatively, instead of applying the adhesive to the stretched elastic strip sections by means of the applicator 11, it can be applied by the applicator 12 directly to those areas of the web 13 which are required to be covered by the elastic strips 2. If hot-melting adhesives are used, the combining roller may be equipped with cooling means.

Claims

1. A method of applying elastic strips to a continuously moving non-elastic web of material in which:~ (a) predetermined lengths are severed from the elastic strip fed in the unstretched state, (b) the severed sections of the elastic strip are stretched to predetermined lengths, (c) adhesive is applied to the stretched sections of the elastic strips, (c) the elastic strip section which have been provided with adhesive, and which are kept stretched, are applied to the continuously moving non-elastic material web and (e) the stretched sections of the elastic strips are held in the stretched state on the continuously moving non-elastic web of material until the adhesive has set.

2. A method of applying elastic strips to a continuously moving non-elastic web of material in which:~ (a) predetermined lengths are severed from the elastic strips fed in the unstretched state, (b) the severed sections of the elastic strip are stretched to predetermined lengths, (c) adhesive is applied to those areas of the non-elastic material web which are required to be covered by the elastic strips, (d) the sections of the elastic strips, which are kept in the stretched condition, are applied to the adhesive on the continuously moving non-elastic material web and, (e) the stretched sections of the elastic strips are held in the stretched state on the continuously moving non-elastic web of material until the adhesive has set.

3. A method according to claim 1, or claim 2, in which the adhesive used is a hot-melting adhesive which is applied to the sections of elastic strips kept in the stretched condition or to those area of the non-elastic material web which are required to be covered by the elastic strips.

4. A method according to claims 2 and 3, in which the non-elastic web of material is cooled before the hot-melting adhesive is applied.

5. A method according to claim 3 in which the parts that have been stuck together are cooled.

6. Apparatus for applying elastic strips to a continuously moving non-elastic web of material according to the method of claim 1, in which a straightening unit is followed by a pair of feed rollers which draws the elastic strips into the apparatus and feeds them over a reversing roller to a cutter roller co-operating with a co-acting roller equipped with holder elements for the elastic strips, the said cutter roller being arranged to sever the unstretched elastic strips while they are held fast on the co-acting roller by their trailing ends and the leading ends of the elastic strips are engaged and stretched by the holder elements of a following stretching roller, which rotates at a high circumferential speed, until the trailing ends are also engaged by the holder elements of the stretching roller after stretching is completed, whereafter the elastic strips are provided with adhesive by an adhesive applicator associated with the stretching roller, and are then applied to the non-elastic web of material which is trained around the combining roller, at the same circumferential speed.

7. Apparatus for cyclically applying elastic strips to a continuously moving non-elastic material web according to the method of claim 2, in which an adhesive applicator for sticking the severed and stretched sections of the elastic strips to the non-elastic material web is so arranged that the adhesive is applied directly to those areas of the non-elastic material web which are required to be covered by the elastic strips.

8. Apparatus for performing the method according to claims 3, 4 and 5, in which the combining roller is in the form of a cooling roller.

9. Apparatus according to claims 6-8, in which the holder elements on the roller and stretching roller are in the form of suction bores to which vacuum is applied.

10. A method of or apparatus for applying elastic strips to a continuously moving non-elastic web of material substantially as specifically described herein with reference to the accompanying drawing.