Wrapping of agricultural bales of rectangular cross section
A method of applying stretch film wrapping to an agricultural bale ( 10 ) which is of rectangular cross section and using a bale wrapper apparatus which comprises: a table which supports the bale ( 10 ) and which operates to rotate the bale generally about its longitudinal axis ( 11 ) during a wrapping cycle; a dispenser reel arrangement ( 12, 13, 16, 17, 20, 21, 24, 25 ) from which stretch film wrapping is withdrawn so as to form successive overlapping windings of film which cover the bale; and means which applies relative rotation between the table and the dispenser reel arrangement about a second axis ( 14 ) which extends substantially perpendicular to said first axis during the wrapping cycle; in which: each winding of film includes a longitudinal edge strip portion and an adjoining longitudinal strip portion; and the longitudinal edge portion has different deformation properties from the deformation properties of said adjoining portion so as to be more readily extensible under a given load than said adjoining portion, and thereby to enable the winding to tighten itself around each corner ( 15 ) of the bale ( 10 ) and thereby at least minimize the generation of creases or wrinkles in the film winding at each corner region of the bale.
1. A method of applying stretch film wrapping to an agricultural bale which is of rectangular cross section using a bale wrapper apparatus which comprises:
supporting the bale on a table;
rotating the bale generally about its longitudinal axis during a wrapping cycle;
withdrawing separate film strips from a plurality of film reels and bringing the film strips into partial overlap to form a film wrapping, said film wrapping comprising a longitudinal edge strip portion comprising a single thickness film, which wraps around at least one corner of said bale, and an adjoining longitudinal strip portion comprising a double thickness film, wherein the longitudinal edge portion has different deformation properties from the deformation properties of said adjoining portion so as to be more readily extensible under a given load than said adjoining portion, such that said stretch film wrapping wraps around said corner in a manner that at least reduces creases or wrinkles in the film winding;
forming successive overlapping windings of the film wrapping so as to cover the bale; and
applying relative rotation between the table and the dispenser reel about a second axis which extends substantially perpendicular to said first axis during the wrapping cycle.
2. A method according to claim 1 , in which the reels are axially displaced one relative to the other so that the film strips are brought into partial overlap to form the film wrapping such that a single thickness film forms said longitudinal edge strip portion and double thickness film forms said adjoining strip portion.
3. A method according to claim 2 , in which the film strips are brought into contact with each other prior to application to the bale, or upon coming into contact with the bale, so as to form a part laminated winding.
4. A method according to claim 1 , in which the film wrapping is obtained from two film reel supplies, of which one supply is wider than the other, and from which separate film strips are withdrawn, and are brought into partial overlap to form the film wrapping such that a single thickness film forms said longitudinal edge strip portion and double thickness film forms said adjoining strip portion.
5. A method according to claim 1 , in which the film wrapping forming the windings on the bale has a central portion forming said adjoining strip portion, and a pair of laterally spaced edge strip portions which are more readily extensible under load than the central portion.
6. A method according to claim 1 , in which the width of said adjoining portion is between ⅓ and ½ of the overall width of the applied film winding.
7. A method according claim 1 , in which the pre-stretch applied to the film wrapping, prior to application of the windings to the bale, is more than70% of the unstretched film length.
8. A method according to claim 7 , in which the stretch level is at least 120% of the unstretched film length.
9. A method according to claim 1 , in which the edge portion is less than 17 microns in thickness, and the adjoining portion is double the thickness of the edge portion.
10. A method according to claim 9 , in which the edge portion is 10 microns in thickness or less, and the adjoining portion is about double the thickness of the edge portion.
11. A bale wrapper apparatus for applying stretch film wrapping to an agricultural bale of rectangular cross section, the bale wrapper apparatus comprising:
a table which supports the bale and operates to rotate the bale generally about its longitudinal axis during a wrapping cycle;
a dispenser reel arrangement comprising a plurality of reels from which stretch film strips are withdrawn and brought together in partial overlap to form a film wrapping, wherein said film wrapping comprises a longitudinal edge strip portion comprising a single thickness film and an adjoining longitudinal strip portion comprising a double thickness film, the longitudinal edge portion wrapping around at least one corner of said bale, and having different deformation properties from the deformation properties of said adjoining portion so as to be more readily extensible under a given load than said adjoining portion, such that said stretch film wrapping wraps around said corner in a manner that at least reduces creases or wrinkles in the film winding; and
means for applying relative rotation between the table and the dispenser reel arrangement about a second axis which extends substantially perpendicular to said first axis during the wrapping cycle so as to form successive overlapping windings of film wrapping which cover the bale.