1. Field of the Invention
The present invention relates generally to food production machinery and, more particularly, to an improved sheeter with spiraled stripper wire and conveyer belt with a landing zone.
2. Description of the Related Art
Machines called “sheeters” are routinely used in production lines that produce tortillas and tortilla chips. In general, as shown in FIGS. 1-3 and 4A-4D, a conventional sheeter consists of a pair of closely-spaced counter-rotating rollers 20, 30 that compress a mass of corn masa 11 (or other dough) into a sheet 12 within a gap between the two rollers. As the sheet 12 exits the gap, it is separated from the back roller 20 using a stripper wire stretched across its width or, more commonly of late and as suggested, by rotating the front and back rollers at slightly different speeds. Another approach to encouragins separation is using a coated back roller (e.g. coated with Teflon®) so that it has a lower coefficient of friction than the front roller (e.g. made with UHMW). The sheet 12 remains adhered to the front roller 30 and, at this point, a patterned “cutter roller” 40 forms shaped dough pieces 70 by cutting a pattern into the sheet 12 by rotating its patterned walls against the front roller 30 through the dough sheet 12. After this, a stripper wire 50 stretched across the width of the front roller 30 strips the chip-shaped pieces and surrounding web of “re-works” (if any), after which the shaped dough pieces 70 land on a take-away conveyer belt 60 that moves the dough pieces 70 onward (e.g. into an oven, not shown). The excess dough 13 (called “re-work”) surrounding the shaped dough pieces 70 (between rows and/or between sequential ones of the shaped dough pieces, depending on the pattern) is rotated upward on the front-roller 30 to merge with the fresh masa located between the rollers.
In the prior art, typically, the front roller 30 is provided with a plurality of grooves that hold flat bands (e.g. 32) (sometimes collectively hereafter “band grooves”). The bands 32 generally serve two purposes. First, because the front stripper wire 50 is threaded beneath the bands 32, the bands 32 help hold the wire 50 against the roller 30 to strip the shaped product pieces (see pieces 71) off of the front roller 30 and onto the conveyor belt 60. The bands 32 also tend to pinch the re-work 13 that is located between product rows to help make that re-work 13 stay with the front roller 30. As shown, these bands 32 are traditionally located between rows of the chip-shaped pieces to help pull the re-work 13 back onto the front roller 30 and rotate it up and around for recombination with the masa, rather than allowing it to land on the take-away conveyer 60 with the chip-shaped pieces 70. When the bands 32 are used with certain product shapes, real estate on the front roller 30 that could otherwise be used for product rows is wasted. In FIG. 4A, for example, there are only ten rows of triangular shaped dough pieces due to the interior band grooves 32. Since the rows of this particular shape (and others) could be placed side-by-side without any unused dough, it is the band grooves 32 alone that are wasting space.
The prior art stripper wire 50 has traditionally had a slight spiral from one end 51 to another end 52. However, due to drag-related forces, the frictional forces associated with the masa and the front roller 30 tends to pull the wire 50 upward to a central high spot 53.
The industry has previously taken different approaches to try and eliminate all bands, or at least eliminate the intermediate bands 32 (leaving only the left-most and right-most bands 31, 31 to return the outer edges of re-work surrounding the product). The applicant's prior patent application Ser. No. 10/346,362 is an example of one such approach, the entire content of which is hereby incorporated by reference. It features a vibrating T-shaped blades rather than a stripper wire. The invention of Ser. No. 10/346,362 may well prove successful, but stripper wires remain popular such that there remains a need for an improved sheeter that uses a stripper wire without intermediate bands to maximize product efficiency.