Method and apparatus for manufacturing variable crimped web material

Abstract

A method of manufacturing a variable crimped web material is provided, including feeding a substantially continuous web material; crimping a first region of the material at a first crimp value; and crimping a second region of the material, adjacent the first region, at a second crimp value, the crimping using a set of two rollers, each being corrugated across at least a portion of its width and corrugated around its circumference, and being configured so the corrugations across the width interleave with each other to crimp the material, so the troughs of the corrugations around the circumference crimp the material at the first crimp value, and so the peaks of the corrugations around the circumference crimp the material at the second crimp value. An apparatus for manufacturing a crimped web material, and a method of manufacturing air flow directing elements for smoking articles are also provided.

Claims

1. An apparatus for manufacturing a variable crimped web material, comprising: a set of rollers comprising a first roller and a second roller, wherein each roller is corrugated across its width, each roller is corrugated around its circumference to alternate between peak sectors and trough sectors, the first and second rollers are configured such that corrugations across the width of the rollers interleave with each other, the peak sectors of the first roller are circumferentially aligned with the peak sectors of the second roller, the trough sectors of the first roller are circumferentially aligned with the trough sectors of the second roller, the first and second rollers are configured to crimp web material between the trough sectors at a first crimp value, and the first and second rollers are configured to crimp the web material between the peak sectors at a second crimp value that is larger than the first crimp value, the first crimp value and the second crimp value being defined as follows: the first crimp value=2r.sub.2/X, and the second crimp value=2r.sub.1/X, wherein r.sub.2 is an outermost radius of the first and second rollers in the trough sectors, r.sub.1 is an outermost radius of the first and second rollers in the peak sectors, and X is a distance between an axis of the first roller and an axis of the second roller: means for detecting an interface between regions of different crimp value on the web material; and cutting means for cutting the crimped web material into sections, the cutting means being controlled by the means for detecting.

2. The apparatus according to claim 1, wherein the corrugations around the circumference of said each roller are formed such that angles and , corresponding respectively to an angle of one of the trough sectors formed by the axis of said each roller and a trough of a corrugation, and an angle of one of the peak sectors formed by the axis of said each roller and a peak of a corrugation, conform to an equation: 360/(+)=an integer.

3. The apparatus according to claim 1, wherein the peak sectors of the corrugations around the circumference of said each roller are provided with rounded edges.

4. The apparatus according to claim 1, wherein said each roller is configured to crimp the web material at a third crimp value.

5. The apparatus according to claim 1, wherein the set of rollers is a kit of rollers comprising at least two rollers.

6. The apparatus according to claim 1, wherein in the trough sectors, peaks of the first roller are separated from corresponding troughs of the second roller by a first distance, in the peak sectors, peaks of the first roller are separated from corresponding troughs of the second roller by a second distance, and the first distance is greater than the second distance.

Description

(1) The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1 shows a side view of an apparatus for manufacturing variable crimped paper;

(3) FIG. 2 shows a schematic cross-section of interleaved rollers used to variably crimp paper; and

(4) FIG. 3 shows a cross-sectional view of an air flow directing element having variable resistance-to-draw along its length;

(5) FIG. 1 shows apparatus 100 for manufacturing variable crimped paper. The apparatus comprises, among other components, interleaved longitudinal crimping rollers 102, and/or variable crimping rollers 104. In a preferred example, the interleaved longitudinal crimping rollers 102 are replaced by the variable crimping rollers 104. The apparatus further comprises a lateral sheet cutting mechanism 106 configured to cut the paper to the required width before it is crimped by the rollers. A bobbin of sheet web material 108, such as paper, is provided and fed into the crimping rollers. The drive and brake mechanism 110 feeds the sheet web material from the bobbin 108. The mechanism 112 ensures that the web material enters the crimping rollers at the desired tension. Control electronics 114 are provided to control the system during operation.

(6) The variable crimping rollers 104 comprise a set of two interleaved rollers. Each crimping roller is corrugated across its width, and also corrugated around its circumference. The crimping rollers are synchronised with each other to ensure that the corrugations around the circumference of the rollers remain aligned.

(7) In use, the crimping rollers force the web material between the interleaved corrugations, which deforms the web material to form the crimp. Crimping the web material reduces the effective width of the web material, and increases the effective thickness of the web material. The crimped web material can then be gathered together and used to form air flow directing elements as described below. Controlling the crimp value of the crimped web material can be used to control the resistance-to-draw of the air flow directing element. Increasing the crimp value increases the resistance-to-draw.

(8) FIG. 2 shows a cross-sectional view of a section of the crimping rollers used to variably crimp the web material. Each roller is corrugated around the circumference. The troughs of the corrugation have an arc angle , and the peaks of the corrugations have an arc angle . The rollers are configured such that the formula 360/(+) is an integer. That is to say, each peak around the circumference of the roller has the same arc length as the other peaks, and each trough around the circumference of the roller has the same arc length as the other troughs. By configuring the rollers in this way the web material can be crimped continuously and provide regions having different crimp values with consistent lengths throughout the continuous operation. The peaks and troughs of the rollers are aligned during use so that different crimp values are applied alternately to the web material as it passes between the rollers.

(9) Section B-B shows a cross-section of the interleaved rollers at the peaks of the corrugations. As can be seen, the crimping roller also has corrugations across the width of the roller. The internal radius of the roller, that is the radius at the troughs of the corrugations across the width of the roller, is shown as r.sub.3, and the radius of the peaks of the corrugations across the width of the roller is shown as r.sub.1. As such, the radius r.sub.1 corresponds to the radius of the peaks of the corrugations around the circumference of the roller. The distance X which is the distance between the axes of the rollers, together with the radiuses r.sub.3 and r.sub.1, are controlled to determine the crimp value applied to the web material.

(10) Section A-A shows a cross-section of the interleaved rollers at the troughs of the corrugations. Similarly to Section B-B, the internal radius of the roller, that is the radius at the troughs of the corrugations across the width of the roller, is shown as r.sub.3, and the radius of the peaks of the corrugations across the width of the roller is shown as r.sub.2. As such, the radius r.sub.2 corresponds to the radius of the troughs of the corrugations around the circumference of the roller. The distance X, together with the radiuses r.sub.2 and r.sub.1 are controlled to determine the crimp value applied to the web material.

(11) Furthermore, the thickness, t.sub.1, of each crimping element having corrugations around the circumference, and the distance, t.sub.2, between each crimping element may also be used to control the crimp value. In addition, the rollers may be offset from vertical alignment, the value of the offset, D, may also be used to determine the crimp value.

(12) As will be appreciated, and as shown in FIG. 2, the radiuses r.sub.1 ad r.sub.2 correspond to the radius of the peaks of the corrugations around the circumference of the roller and the troughs of the corrugations around the circumference of the roller respectively.

(13) In one particular example, the various parameters have the following values: r.sub.1=99.3 mm r.sub.2=98.8 mm r.sub.3=98.3 mm X=198.2 mm C=0.6 mm =8.07 =6.92 D=0 t.sub.1=1 mm t.sub.2=1.2 mm first crimp value=0.997 second crimp value=1.002

(14) In a further particular example, the various parameters have the following values: r.sub.1=80.2 mm r.sub.2=79.7 mm r.sub.3=79.2 mm X=160 mm C=0.6 mm =5 =2.5 D=0 t.sub.1=1 mm t.sub.2=1.2 mm first crimp value=0.996 second crimp value=1.003

(15) Finally, as shown in FIG. 2, the peaks of the corrugations have rounded corners to reduce the stress applied to the web material during crimping, and therefore the risk of breaking the web material is reduced.

(16) By corrugating the crimping rollers around the circumference of the rollers, alternate crimp values can be applied to the web material. The first crimped region corresponding to the region of web material crimped at the first crimp value by the troughs of the corrugations around the rollers is approximately r.sub.2.Math. in length. The second crimped region corresponding to the region of web material crimped at the second crimp value by the peaks of the corrugations around the rollers is approximately r.sub.1.Math. in length. To determine the length of the first and second crimped regions herein, and are in radians.

(17) FIG. 3 shows an air flow directing element 300 formed using the crimped web material manufactured as described above. The air flow directing element comprises a series of regions 302, 304 and 306, and a hollow tube 308 at the centre of the air flow directing element. The air flow directing element is wrapped in a substantially air-impermeable wrapper 310. The wrapper 310 is provided with perforations 312 which act as air inlets when the air flow directing element is used in a smoking article.

(18) To form the air flow directing element, the crimped web material is gathered together around the hollow tube 308, and then wrapped in the substantially air-impermeable wrapper 310.

(19) The region 302 corresponds to a half length first region having a first crimping value, the region 304 corresponds to a full length second region having a second crimping value, and region 306 corresponds to a half length first region having a first crimping value. As will be appreciated, the air flow directing element is thus symmetrical about a transverse centre line. Forming a symmetrical air flow directing element reduces the complexity of later smoking article manufacture as the orientation of the air flow directing element is not relevant.

(20) The substantially continuous crimped web material having alternating regions of a first crimp value and a second crimp value is cut into suitable lengths. In the preferred embodiment, the crimped web material is cut to such a length that each section comprises web material sufficient for four air flow directing elements. The crimped web material is cut such that the first region is divided substantially equally, so that each crimped web material section comprises a half length first region, then four full length second regions with full length first regions provided in between, and then a final half length first region. In this way, the crimped web material section can be used to form a so-called four-up air flow directing element for later use in manufacturing smoking articles.

(21) The measured resistance-to-draw of each region of a particularly preferred embodiment of the air flow directing element are as follows: about 56 mmH.sub.2O for first the half length first region; about 168 mmH.sub.2O for the full length second region; and about 56 mmH.sub.2O for the second half length first region. The longitudinal lengths of each region of a particularly preferred embodiment of the air flow directing element are as follows: about 7 mm for first the half length first region; about 12 mm for the full length second region; and about 7 mm for the second half length first region.