Presses – Binding – Methods
Reexamination Certificate
2000-01-29
2003-03-25
Gerrity, Stephen F. (Department: 3721)
Presses
Binding
Methods
C100S010000, C100S026000, C100S0330PB
Reexamination Certificate
active
06536336
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an apparatus and method useful for automatically tying bales of cotton or other fibers, and in particular, to an automatic bale tying apparatus for tying a plurality of plastic straps around a bale while reducing the stresses at the joint of the baling strap material.
BACKGROUND OF THE INVENTION
In the cotton industry, the normal method of banding or tying cotton bales has been to have workmen direct a tie, such as a band or wire, around a bale and then secure the ends of the ties appropriately depending on the design of the tie. In the cotton or fiber industry, there are generally three ways in which to secure a bale after a bale has been pressed. Pertinent securing means include pre-formed steel wires that have interlocking ends pre-formed into loops which engage one another during the tying operation, flat ribbon-steel bands which have their ends inserted into a crimp by which they are secured, and flat thermoplastic strapping material, typically polyethylene or polyester.
Steel pre-formed wires have a loop manufactured into each end which are interlocked around a bale forming a square knot. When the pressure is released from the bale, the knot formed by the interlocking loops pulls tight and retains the bale against This paper or fee is being deposited with the further expansion. In a conventional bale-tying operation, two workmen (one on each side of the baling press) manually bend the wires around the bale and secure the ends of the wires together in a wire tie guide assembly. The wires are normally tied together sequentially, one at a time. Alternatively, wires might be tied in a hydraulically operated wire tying device for mounting on a baling press, which ties a plurality of wires having pre-formed interlocking ends around a bale formed in the press. Pivotally mounted wire bend assemblies take the place of workmen on each side of the baling press, and bend the tie wires around a bale by inserting the ends of the tie wires into a wire tie guide assembly. However, workmen are still required to individually load each of a plurality of tie wires into the wire bend assemblies.
Although an improvement over the manual-type bale tying operation, a hydraulically operated wire tying device still exhibits certain problems which slow the ginning process. Exact timing is required for the sequence of events which make up a wire tying operation. If a wire does not follow the correct path at the correct time, several factors can combine to prevent the interlocking ends of the wire from engaging in a knot. In particular, the interlocking ends of the wires are conventionally oriented such that the loops are disposed in the generally horizontal plane. This geometric orientation forces the wire closers to be constructed with relatively wide cavities, in order to accommodate the wide aspect ratios of the loops. This, in turn, allows the wires a greater degree of freedom of movement within the cavities. Consequently, there is a greater probability of one wire merely sliding past another, without their loops engaging in a knot.
In addition, press wear, both alone or in combination with component manufacturing tolerances, can cause a follow block to vary its position or orientation both vertically or from side to side. Consequently, the wire bend assemblies may not be in alignment with a wire tie guide assemblies. All the above-described cases result in mis-ties, with a consequent loss of time and possible damage to the press.
Bale tying using flat steel straps is hindered primarily by the cost of the strapping material, the complexity of the machinery used, and the speed at which the machinery is able to operate. In addition, the sheer weight of steel strap tie material and its substantially sharp edges, makes it cumbersome and particularly dangerous to handle. Further, once it is removed from a bale, steel strapping material is not easily recycled by an end user. Removal is difficult and, once removed, a large volume of sharp material must be colleted and crushed together to form it into a package that can be more easily handled. Notwithstanding the foregoing, steel strap tie material is further disadvantageous in that its weakest spot (the joint) is located in the highest stress position on the bale, because the forming machinery is only able to apply a joint (crimp) on the side of the bale, i.e. the bale position with the highest degree of lateral pressure or stress. This results in significant tie breakage with a consequent loss of bale integrity.
Conversely, plastic or non-ferrous strapping is an ideal material for strapping bales of cotton or other fibers. Plastic is relatively light in weight and can be formed into a variety of widths and thicknesses, and with soft edges, which allows easy handling and lowers shipping costs. Plastic or non-ferrous strapping material is very competitive with wire ties, on a cost per bale basis, and is easily adaptable to fully automatic tying machinery. Plastic or non-ferrous strapping material is readily recyclable by the end user and is considered substantially safer than steel strapping material, particularly in instances of strap breakage.
Because of the particular orientation of conventional plastic strap automatic tying machinery, certain disadvantages arise when one adapts strapping and joint forming apparatus to the structure of a baling press. Typically, automated thermoplastic strapping machinery, including a material feeder, tensioner, cutting shear and joint former, are so large that they are precluded from being able to be placed anywhere except on the side of the bale. As was the case with steel strapping material discussed above, thermoplastic strapping joint formation takes place in the region of the bale that exhibits the highest degree of tension stress.
In this regard, conventional thermoplastic strapping machinery must typically wait until a baling press has completed operation and has reached “shut height”, before it begins the strapping operation. The strapping head pulls strapping material off of a spool and directs it around the bale through a series of shoots, until the front edge of the strapping material has completed its circuit of the bale and is directed back to the region of the strapping head. The strap is then pulled tight around the bale to a pre-determined tension and the strap is then cut with a shear. The two ends are then joined by a friction weld, hot knife weld, or other similar joint forming operation, and maintained together until the joint is cool, in which time the strap is released and allowed to carry the tension load of the bale.
Referring now to
FIGS. 1
a
,
1
b
and
1
c
, there is shown a semi-schematic view of cotton, or other fibers, being pressed into a bale between the platens of a hydraulic press in accord with the prior art. Typically, fiber is pressed by a large hydraulic cylinder out of a box that measures approximately 30 inches wide by 54 inches long and 144 inches deep. Such a box is typically filled with approximately 500 pounds of cotton lint which is subsequently pressed into a 20 inch by 54 inch bale measuring approximately 20 to 22 inches tall (in accordance with the illustration of
FIG. 1
a
). The box from which the bale is pressed has been omitted for the sake of illustrational clarity.
Strapping material, in the form of thermoplastic straps, are inserted through guide slots in the upper and lower platens, and are secured on the sides of the bale (as shown in the illustration of
FIG. 1
b
). Once the bale is tied, the press is released and the bale is free to expand to the constraints of the straps. As shown in the illustrated embodiment of
FIG. 1
c
, the bale is then dumped out of the press, making way for a subsequent box loaded with an additional 500 pounds of cotton lint for pressing into the next bale.
It should be noted that conventional thermoplastic strapping systems typically consist of three laterally spaced-apart strapping heads, such that the unit must be indexed in order to tie the requisite number of straps (typically 6
Actis Bradley P.
Jaenson Howard W.
Christie Parker & Hale LLP
Gerrity Stephen F.
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