Apparatus and method for applying parallel flared elastics to disposable products and disposable products containing parallel flared elastics
An apparatus for applying elastics to a running web including a crank and arm, the arm arranged to reciprocate from side to side during use and having a laydown carriage carried on the arm, the laydown carriage including at least one eyelet arranged to support an elastic strand, the assembly further including a shoe guide.
1. A method for applying parallel flared elastics to a web comprising:
providing a running web along a machine direction;
providing a plurality of elastic threads to a reciprocation assembly, the reciprocation assembly comprising:
a crank;
a laydown carriage comprising a plurality of carriage strand guides;
an arm coupled to the crank and to the laydown carriage; and
a shoe guide assembly comprising a plurality of shoe strand guides spaced apart from each other at a variable spacing;
reciprocating movement of the laydown carriage along a reciprocation axis via rotation of the crank about a crank rotation axis; and
applying the plurality of elastic threads to the running web according to a pattern corresponding to an engagement of the plurality of elastic threads with the reciprocating movement of the laydown carriage and with the shoe guide assembly, wherein the spacing between the shoe strand guides is varied to influence the laydown of the elastic strands so that a distance between successive strands of the elastic threads is varied.
2. The method of claim 1 wherein the pattern is sinusoidal.
3. The method of claim 1 wherein the pattern comprises:
a first region of each of the plurality of elastic strands running in parallel to one another, the elastic strands separated from each other in the machine direction by a first distance within the first region;
a second region of each of the elastic strands running continuously away from the first region along a unique angle;
a third region of the plurality of elastic strands running in parallel to one another, separated by a second distance in the machine direction, wherein the second distance is larger than the first distance.
4. The method of claim 1 wherein the shoe guide assembly further comprises a pair of shoe guide members spaced apart from each other along the reciprocation axis, each shoe guide member comprising a respective portion of the shoe strand guides.
5. The method of claim 4 further comprising:
causing a first elastic strand of the plurality of elastic strands to slidingly engage one of the shoe strand guides of one of the shoe guide members of the pair of shoe guide members when the laydown carriage is positioned in a first end reciprocation location along the reciprocation axis; and
positioning the first elastic strand between the pair of shoe guide members when the laydown carriage is positioned in a second end reciprocation location along the reciprocation axis, the second end reciprocation location opposite to the first end reciprocation location.
6. The method of claim 4 further comprising:
causing a first elastic strand of the plurality of elastic strands to slidingly engage one of the shoe strand guides of one of the shoe guide members of the pair of shoe guide members when the laydown carriage is positioned in a first end reciprocation location along the reciprocation axis; and
causing the first elastic strand to slidingly engage one of the shoe strand guides of the other of the shoe guide members of the pair of shoe guide members when the laydown carriage is positioned in a second end reciprocation location along the reciprocation axis, the second end reciprocation location opposite to the first end reciprocation location.
7. A method for applying parallel flared elastics to a web comprising:
providing a running web along a machine direction;
providing a plurality of elastic threads to a reciprocation assembly, the reciprocation assembly comprising a laydown carriage comprising a plurality of carriage strand guides and a shoe guide assembly comprising a plurality of shoe strand guides spaced apart from each other at a variable spacing; and
applying the plurality of elastic threads to the running web according to a pattern corresponding to an engagement of the plurality of elastic threads with reciprocating movement of the laydown carriage and with the shoe guide assembly, wherein the spacing between the shoe strand guides is varied to influence the laydown of the elastic strands so that a distance between successive strands of the elastic threads is varied.
8. The method of claim 7 wherein the pattern is sinusoidal.
9. The method of claim 7 wherein the pattern comprises:
a first region of each of the plurality of elastic strands running in parallel to one another, the elastic strands separated from each other in the machine direction by a first distance within the first region;
a second region of each of the elastic strands running continuously away from the first region along a unique angle;
a third region of the plurality of elastic strands running in parallel to one another, separated by a second distance in the machine direction, wherein the second distance is larger than the first distance.
10. The method of claim 7 wherein the shoe guide assembly further comprises a pair of shoe guide members spaced apart from each other along the reciprocation axis, each shoe guide member comprising a respective portion of the shoe strand guides.
11. The method of claim 10 further comprising:
causing a first elastic strand of the plurality of elastic strands to slidingly engage one of the shoe strand guides of one of the shoe guide members of the pair of shoe guide members when the laydown carriage is positioned in a first end reciprocation location along the reciprocation axis; and
positioning the first elastic strand between the pair of shoe guide members when the laydown carriage is positioned in a second end reciprocation location along the reciprocation axis, the second end reciprocation location opposite to the first end reciprocation location.
12. The method of claim 10 further comprising:
causing a first elastic strand of the plurality of elastic strands to slidingly engage one of the shoe strand guides of one of the shoe guide members of the pair of shoe guide members when the laydown carriage is positioned in a first end reciprocation location along the reciprocation axis; and
causing the first elastic strand to slidingly engage one of the shoe strand guides of the other of the shoe guide members of the pair of shoe guide members when the laydown carriage is positioned in a second end reciprocation location along the reciprocation axis, the second end reciprocation location opposite to the first end reciprocation location.