CROSS-REFERENCE TO RELATED APPLICATION

This application is a national phase entry of, and claims priority to, International Application No. PCT/SE2017/050872, filed Sep. 1, 2017. The above-mentioned patent application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

This application relates to a separation unit for separating a web material such as paper towels, tissue paper, or nonwoven material along preformed lines of weakness.

This application further relates to a dispenser for a web material, comprising a housing defining a web material reservoir, a dispensing opening, and a separation unit.

BACKGROUND

Many types of dispensers are available on the market today for web material provided with pre-formed weakening lines, such as perforation lines, dividing the web material into individual products for use, e.g., as towels or wipes. The dispensers may be adapted for dispensing web material initially provided in the form of a roll or in the form of a folded stack.

Automatic dispensers may be electronically manoeuvred, and store and advance the paper towels with different kinds of control devices, sensors and power sources available. In particular, touch-free dispensers may be used to automatically feed a towel to a user. Manual dispensers may rely only on the force submitted by a user, e.g. pulling the outermost towel of the web material, in order to advance paper towels to the user.

A dispenser for web material with preformed lines of weakness may be provided with a separation unit for separating a sheet of web material along a line of weakness from the web material in the dispenser. The separation unit may comprise a nip through which the web material is arranged to pass. A line of weakness of the web material may break within the nip or outside the nip as a user pulls on the leading portion of the web material.

However, to realize the dispenser as described above a number of problems must be solved, including separating the webs correctly along the lines of weakness, feeding the next portion of the web to be separated to the separation unit, and presenting the leading end of the web to the next user. Furthermore, separation shall be possible for different types of web materials and web materials having different lengths between the lines of weakness.

International PCT Patent Application Publication No. WO2014/065738 concerns a separation unit for separating a perforated web material along preformed lines of weakness. The separation unit has a width direction and comprises at least a first shaft having a longitudinal axis extending in said width direction and a web width extending in said width direction, and at least a second shaft having a longitudinal axis extending parallel with said longitudinal axis of said first shaft and a web width extending in said width direction. The longitudinal axis of said second shaft is positioned at a distance from said longitudinal axis of said first shaft, said distance extending in a direction perpendicular to said width direction. Each of said first and said second rollers is provided with at least one protrusion element extending perpendicularly from said axes, wherein each of said protrusion elements has a maximum width in said width direction, a maximum radial extension from said rotational axes, an inner portion adjacent to said rotational axes, and an outer portion remote from said rotational axes, wherein said outer portions of said protrusion elements on said first shaft are arranged in a staggered relationship with said outer portions of said protrusion elements on said second shaft such that the outer portions of said protrusion elements on said first shaft are partially overlapping with said outer portions of said protrusion elements on said second shaft with a radial overlap length, thus forming an undulating passage for a web material between said rollers.

By the separation unit of WO2014/065738, the lines of weakness of a web material will be broken as a result of the web material passing through the undulating passage. This type of separation unit is particularly useful when it is desired to accomplish separation of a web material comprising lines of weakness, while treating the web material leniently. Hence, dispensing of relatively soft and/or weak web materials may be enabled without risk of the dispensing damaging the web material. For example, using a separation unit as in WO 2014/065738, dispensing of web material may be performed by a user pulling the tail of the web material with a pull-out force in the range about 4-7 N.

In particular, the separation unit of WO2014/065738 has shown to be useful when dispensing web material comprising at least two webs, each web being divided into individual sheets by lines of weakness, where the two webs are arranged in relation to one another such that the lines of weakness of the first web and the lines of weakness of the second web are offset with respect to one another along the webs. For separating such a web, it is of importance that while the separation along a line of weakness of one of the webs is performed, the separation unit should not damage the web material of the other web, which is located adjacent the line of weakness to be separated.

A web material as described in the above may be provided in the form of a roll or in the form of a folded stack. International PCT Patent Application Publication No. WO2014/098669 discloses an example of such a web material.

Although the separation unit of WO2014/065738 may provide highly reliable separation along the weakening lines of web material, it has been found that for some web materials, the reliability of the separation may be even further improved. Thus, it would be desirable to provide a separation unit that addresses these and other deficiencies in the known art.

SUMMARY

To address these and other problems with conventional designs, a separation unit is provided according to one embodiment for separating a web material having a web width along preformed lines of weakness, the separation unit having a width direction and including at least a first shaft extending along a first longitudinal axis in the width direction and at least a second shaft extending along a second longitudinal axis in parallel with the first shaft, the second longitudinal axis being positioned at a distance from the first longitudinal axis in a direction perpendicular to the width direction.

The separation unit also includes at least one first protrusion element extending perpendicularly from the first shaft and arranged to be rotatable about the first longitudinal axis, and at least one second protrusion element extending perpendicularly from the second shaft and arranged to be rotatable about the second longitudinal axis. In a use position of the separation unit, the first and second protrusion elements are arranged in a staggered relationship such that the protrusion element of the first shaft is partially overlapping with the protrusion element of the second shaft with a radial overlap length in a direction perpendicular to the shafts, thus forming an undulating passage for the web material between the shafts with the web width extending in said width direction. At least one contact element is arranged in biased abutment against at least one of the first and second protrusion elements, in a direction perpendicular to the first or second longitudinal axis about which the at least one protrusion element is arranged.

The statement “the at least one contact element is arranged in biased abutment against at least one of the first and second protrusion elements when the separation is in a use position” in the context of this invention means that, when the separation unit is in a position useful for separating web material, but no web material is present in the separation unit, the contact element will directly abut the at least one first or second protrusion element. When a web material is present in the separation unit, the web material may pass between the contact element and the protrusion element. When a weakening line reaches the contact element, the biasing pressure thereof will assist in rupturing the web material at the part of the weakening line adjacent the contact element. The complete separation of the web material along the full width of the weakening line is ascertained by the passing of the web material through the undulating passage.

The contact element may be designed so as to provide frictional contact towards the protrusion element, and hence to the web material which, in use, will be positioned in between the protrusion element and the contact element. An outer surface of the contact element may be adapted so as to provide sufficient friction. For example, the outer surface of the contact element may be smooth or textured. Also, the material of the contact element may be selected so as to provide the desired friction.

In some embodiments, the contact element is arranged so as to non-rotatable about the first and/or second longitudinal axis.

In further embodiments, the contact element is arranged in connection to the first or second longitudinal axis opposing the at least one protrusion element.

For example, the contact element may be connected to the first or second shaft. In another example, the contact element may be connected at or adjacent shaft fixation members for mounting the shafts in the separation unit.

In yet further embodiments, the contact element is arranged so as to be fixed in relation to the first longitudinal axis of the first shaft when arranged in biased abutment against a protrusion element of the second shaft.

In another embodiment, the contact element is arranged so as to be fixed in relation to the second longitudinal axis of the second shaft when arranged in biased abutment against a protrusion element of the first shaft.

In some embodiments, the contact element includes an outer surface forming a pressure nip with the protrusion element. By “pressure nip” it is to be understood that a web material passing the pressure nip will be pressed between the contact element and the protrusion element. Hence, no cutting or piercing takes place. It will be understood that in such a pressure nip, the contact element may be fixed in relation to the longitudinal axis of the protrusion element, whereas the protrusion element may be rotatable.

In further embodiments, the at least one contact element is forming a concave outer surface towards the at least one protrusion element, as seen in a plane perpendicular to the width direction.

In another embodiment, the at least one contact element is forming a convex outer surface towards the at least one protrusion element, as seen in a plane perpendicular to the width direction.

In yet further embodiments, the at least one contact element is forming a straight outer surface towards the at least one protrusion element, as seen in a plane perpendicular to the width direction.

In another embodiment, the at least one contact element is arranged in biased abutment against at least two protrusion elements.

In some embodiments, the at least one first contact element is arranged in biased abutment against at least one protrusion element of the first shaft, and at least one second contact element is arranged in biased abutment against at least one protrusion element of the second shaft.

In another embodiment, the separation unit includes a biasing element arranged to bias the contact element towards the protrusion element, preferably the biasing element is a spring.

In a further embodiment, the first shaft is movably suspended, perpendicularly to the first longitudinal axis, and the biasing element is arranged to bias the first shaft towards the second shaft.

In yet another embodiment, the distance between the first and second longitudinal axes of the first and second shafts is 10 to 30 mm, preferably 15 to 25 mm.

In some embodiments, the distance between the longitudinal axis of the first and second shafts is adjustable. Preferably, the adjustment is enabled by the biasing element.

In another embodiment, the longitudinal axis of the second shaft is fixed.

In a further embodiment, the separation unit includes a first guiding part fixedly arranged in relation to the first longitudinal axis of the first shaft, and including a first guiding surface for the web material. Advantageously, the contact element is formed by at least a part of the first guiding surface.

In yet another embodiment, the separation unit includes a second guiding part, fixedly arranged in relation to the second longitudinal axis of the second shaft, and includes a second guiding surface for the web material. Advantageously, the contact element is formed by at least a part of the second guiding surface.

In some embodiments, the protrusion elements are disc elements.

In another embodiment, the protrusion elements are fixedly arranged with respect to the shaft, respectively.

In a further embodiment, the protrusion elements are rotatably arranged with respect to the respective shaft.

In yet another embodiment, each one of the first and second shaft is provided with a plurality of protrusion elements being spaced along the longitudinal axes, preferably between two and eight protrusion elements, most preferably between four and six protrusion elements.

In a further embodiment, each of the first and the second shaft has a central portion and peripheral portions in the width direction, and the spacing between the protrusion elements is greater in the central portion than in the peripheral portions, on at least one of the first and second shafts, preferably both of the first and the second shaft. In one example, at least one of the first and second shafts includes at least a first, a second and a third protrusion element, and the spacing between the first and the second protrusion elements along the width direction of the shaft differs from the spacing between the second and the third protrusion elements along the width direction of the same shaft. Alternatively, at least one of the first and second shafts includes a plurality of protrusion elements, the protrusion elements being arranged with the same mutual spacing along the shaft.

In another embodiment, each protrusion element has a maximum radial extension from the respective longitudinal axis, the maximum radial extension being between 5 to 50 mm, preferably 5 to 30 mm, more preferably 10 to 20 mm, or most preferably 12 to 18 mm.

In a further embodiment, the maximum widths of the protrusion elements may be 4 to 20 mm, preferably 5 to 10 mm, most preferably 6 to 8 mm.

In yet another embodiment, the radial overlap length is 2 to 40 mm, preferably 2 to 20 mm, more preferably 3 to 12 mm, or most preferably 4 to 10 mm.

In some embodiments, the protrusion elements of the separation unit may all be of the same maximum radial extensions and the same maximum widths. In this case, the protrusion elements of the separation unit may all be uniform.

In another embodiment, at least two protrusion elements of the separation unit have different maximum radial extensions and/or different maximum widths.

In a further embodiment, the axial spacing between each two protrusion elements on the same shaft is greater than the maximum width of each protrusion element.

According to another embodiment of this invention, there is also provided a dispenser for a web material comprising preformed lines of weakness, the dispenser including a housing defining a web material reservoir, and a dispensing opening, the dispenser includes a separation unit as described above.

In another embodiment, the dispenser may include a guiding element determining a correct tension and path of the web material.

The dispenser may further include a web material contained inside the housing. The web material includes preformed lines of weakness and may be Z-folded to form a stack, or be in the form of a roll.

A leading portion of the web material may be configured to be supported in a dispensing path from the reservoir to the dispensing opening. The leading portion may extend upwardly from the top of the stack of the web material, or from the peripheral or central part of the roll.

The preformed lines of weakness may be perforation lines formed by alternating bonds and slots and having the perforation strength between 20-80 N/m, preferably 30-45 N/m measured using SS-EN ISO 12625-4:2005. This perforation strength may for instance be achieved by using perforation lines wherein the total bond length/(the total bond length+total slot length) is between 4% and 10%. It is desired to form perforation lines which are strong enough to enable feeding of the web material, but which are also weak enough to enable separation of the sheets along the perforation lines using the separation unit of the present invention. In this context, it is known that also other parameters may influence the strength of the perforation line, such as the paper quality, and the size, shape and distribution of the slots and bonds. However, it is believed that the above-mentioned measure is useful for guiding the person skilled in the art when selecting suitable perforation lines.

The web material may be a two-layer structure, i.e. the web material may include at least a first web layer divided into sheet products defined between longitudinally separated preformed lines of weakness extending across the first layer; and at least a second web layer divided into sheet products defined between longitudinally separated lines of weakness extending across the second web layer. The web layers may be interfolded so that the lines of weakness of the first web layer are offset from the lines of weakness of the second web layer in a longitudinal direction.

Further, the dispenser may include a feeding mechanism, i.e. a motor to advance a web through the dispenser.

Further features of, and advantages with, the present invention will become apparent when studying the following detailed description. Those skilled in the art will realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.

