Patent Application
20090038161
1. Field of Invention
This invention pertains to a device for cutting lengths of moving zipper material in the manufacture of reclosable packages. The device includes two opposed stationary blades, wherein the zipper passes therebetween, and a double-edge reciprocating blade which cuts the zipper material on both the up and down strokes of a reciprocation cycle.
2. Description of the Prior Art
The prior art of methods of manufacture of reclosable packages is very well-developed and generally satisfactory for its intended purposes in most respects. However, as with virtually all methods of manufacture, there is always the desire to increase production speeds and reduce production costs.
Many methods of manufacture of reclosable packages use lengths of zipper material which are provided in the machine direction, and which must be cut into individual package-width lengths sometime during the manufacturing process. Sometimes, this requires intermittent motion of the zipper material. That is, the zipper length must be stopped in order to perform the cutting reliably. This intermittent stopping and starting of the zipper material is increasingly problematic at higher production speeds.
Previous designs have used a four-pointed star-shaped cutter which rotated ninety degrees during every cutting cycle. This design, however, is too large and complicated for some applications.
It is therefore an object of the present invention to provide a cutter for lengths of zipper material in the manufacturing process of a reclosable package, wherein increased manufacturing speeds can be achieved.
It is therefore a further object of the present invention to provide a cutter for lengths of zipper material in the manufacturing process of a reclosable package, wherein the length of zipper material can be cut while continuously moving, without the need for intermittent stopping of the zipper length during the cutting process.
These and other objects are attained by providing an apparatus with two stationary or fixed opposed blades with a gap therebetween, the zipper material passing though the gap. The apparatus further includes a reciprocating two-edge blade which can cut on both the down-stroke and the up-stroke.
Further objects and advantages of the invention will become apparent from the following description and from the accompanying drawings and claims, wherein:
Referring now to the drawings in detail, wherein like numerals refer to like elements throughout the several views, one sees that
Casing 12 is provided from which upper and lower blade supports 15, 17 extend. Upper and lower blade supports 15, 17 are typically integral with, or firmly affixed to, casing 12. Upper and lower opposed stationary blades 14, 16 are replaceably engaged by, and seated in, respective upper and lower blade supports 15, 17. Upper opposed stationary blade 14 includes downwardly directed cutting edge 18 while lower opposed stationary blade 16 includes upwardly directed cutting edge 20. Upper opposed stationary blade 14 is immediately over lower opposed stationary blade 16 in an opposed coplanar relationship. Gap 22 is formed between upper and lower opposed stationary blades 14, 16 through which the moving length of zipper material 100 passes, typically continuously moving in the machine direction. Length of zipper material 100 may have nothing attached to it or, in some applications, may have other portions of the reclosable package (not shown) attached. Cutting apparatus 10 is well-adapted, in some applications, for separating the completed reclosable packages from each other, particularly when the length of zipper material 100 provides the connection between subsequent reclosable packages in the manufacturing process, and when the series of completed packages is continuously moving.
Reciprocating blade 24 reciprocates within slot 26 which is formed immediately adjacent and parallel to upper and lower stationary opposed blades 14, 16 and upper and lower blade supports 15, 17. Reciprocating blade 24 includes linear guide 25 which is slidably captured within slot 26 and which can be seen protruding from the bottom of cutting apparatus 10 in
Blades 14, 16 and 24 are typically made from metal, such as tool steel or stainless steel selected for its ability to maintain a sharp edge. Additionally, upper and lower blade supports 15, 17 may include internal springs (not shown) to urge upper and lower opposed stationary blades 14, 16 horizontally in order to minimize any horizontal gap between the upper and lower opposed horizontal blades 14, 16 and the reciprocating blade 24.
Two-way gas-driven cylinder 32 is affixed to the top of casing 12. Two-way gas-driven cylinder 32 includes an internal piston (not shown) to which reciprocating blade 24 is affixed or otherwise mechanically responsive. Two-way gas-driven cylinder 32 includes an upper gas inlet 34 and a lower gas inlet 36. By injecting high-pressure gas into upper gas inlet 34, the internal piston is driven downwardly thereby driving the reciprocating blade 24 to the lower position (see
Other equivalent methods of inducing the reciprocating motion of blade 24 will be apparent to those skilled in the art after review of the present disclosure.
In this manner, by timing (or by synchronizing with the distance traveled by length of zipper material 100 or other similar methods) the alternation of high pressure gas injected into upper and lower gas inlets 34, 36, a reciprocating motion of reciprocating blade 24 can be achieved, thereby cutting the moving length of zipper material on both the upward and downward strokes.
Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.
