Bag Making Machine

Abstract

A perforator roller assembly for use in bag making machines. The assembly includes a pair of cooperating rollers, one holding perforating toothed blades and the other serving as an anvil for said blades. The blades are mounted in individual holders which are separately adjustable as to angular and axial positioning and also replaceable with other blades of different pitch diameters.

Parent Case Text

This application is a divisional of application Ser. No. 737,640 filed June 17, 1968, now U.S. Pat. No. 3,561,332. The subject matter of this application relates specifically to the perforator assembly disclosed in the parent application.

Description

The perforator assembly which is the subject of this invention has particular utility in the machine of the parent application; however, it is also applicable to many other machines wherein a perforating operation is performed.

Accordingly, it is an object of the present invention to realize an improved perforator assembly which is capable of repeatedly effecting a line of perforations in a longitudinally travelling sheet material in a direction transverse to the line of travel of the sheet.

It is a further object of this invention to realize an improved perforator assembly as aforesaid and which is made up of separate toothed blades which are individually adjustable relative to each other as to axial and angular positioning.

It is a further object to realize such an improved assembly as mentioned and wherein the said blades are easily replaceable with other blades of a different pitch diameter from the first.

Other objects are those which are inherent in the features disclosed herein of which is detailed description follows of preferred embodiments with reference being made to the accompanying drawings, wherein:

FIG. 1 is a top plan view of a portion of a bag making machine according to the parent application and wherein is shown the perforator according to this invention;

FIG. 2 is an elevation view of machine of FIG. 1 wherein is also shown the aforesaid perforator;

FIG. 3 is a schematic end view of a perforator assembly according to this invention;

FIG. 4 is a partial plan view of a blade used in a perforator of this invention;

FIG. 5 is a plan view of a paper web showing the perforations effected therein by perforator means according to this invention; and

FIGS. 6 and 7 are respective views of a bag produced by perforator means according to this invention.

The respective drawing figures include reference numerals relating to parts fully described in the parent application and which it is not necessary to describe herein, it being understood that any parts of the parent application essential to an understanding of the present invention are incorporated by reference hereinto.

Perforator roller 12 comprises a central power driven shaft 13 about which are clamped removable sleeves 14 which in turn comprise a pair of diametrically opposed radial arms 16 at the ends of which are demountably attached the blade holders 15. Sleeves 14 are fixed relative to said shaft 13 by means such as set screw 17. The blade holders 15, in turn, are bolted onto the ends of arms 16 by means such as machine screws 18, said holders 15 removably carrying the perforator blades 19.

It will be noted in FIGS. 1 and 2 that the disclosed main perforator roller 12 is made up of four separate sleeves 14, denoted 14a to 14d, positioned successively along the axis of shaft 13 with a middle space x separating the two inner sleeves 14b and 14c. The space X corresponds to the non-perforated extent 1' of web W (see FIG. 5) while the sleeves 14a and 14d correspond to the portions a and d of perforation line 1 and sleeves 14b and 14c correspond to portions b and c.

With reference to FIGS. 6 and 7, it will be seen that the completed bag is in the form of a flat tube having an open upper end and a closed bottom end. Primarily, the tube itself is defined by two flat layers which are integrally joined along straight side edges and which for the sake of convenience will be called the top T' and bottom B' layers of the bag and correspondingly of the tube while it is still in the machine.

Following the advance of the web from left to right in FIG. 5, it is seen that the outer perforations a and d of two successive perforation lines ultimately constitute the opposite edges a-d of the top layer T' while the laterally inner perforations b and c of two successive perforation lines ultimately constitute the opposite edges b-c of the bottom layer B'.

Since the outer perforations a-d are longitudinally offset from the inner perforations b-c, each bag and tube top layer T' comprises a lip `f` extending longitudinally beyond edge b-c at one end of the tube bag length (that is: the tube length between two successive lines of perforations 1--1) and each bag and tube bottom layer B' comprises a lip `f` extending longitudinally beyond edges a-d at the opposite end of the tube bag length. The lip `f`' is ultimately folded over back over the top layer T' and glued thereto to form a closed bottom for the bag, this occurring when the bag is on the main cylinder.

An important feature of the perforator roller assembly 12 is that the perforator blades 19a-d are carried at an angle relative to a radial line extending from the axis of shaft 13. Specifically, (see FIG. 3) blade 19 forms an angle `z` of from 15.degree. to 45.degree. relative to straight line r--r which interconnects the respective axes of rotation of the perforator and anvil rollers, said angle being measured at the moment that the rotary arc of the tips of the blade teeth first intersects the rotary arc of the surface of the anvil roller, said teeth, as is well known, penetrating into the resilient covering on the anvil roller along the extent of overlap of the two arcs. The significance of this angular disposition of the blades 19 is that the blade cutting teeth, after they have perforated the web, separate from the web in a very smooth manner without becoming snagged or caught in the web. If the plane of blades 19 extended radially from the axis of shaft 13, as is conventional, the blade teeth would tend to shovel beneath the web and thereby lift the web away from the anvil roller 11 as the blades rotated away from said roller. On the other hand, by being angled backwardly, as disclosed herein, the blade teeth 21 are drawn out of the web in a generally perpendicular direction relative to the web surface rather than along a circular arc and this provides a clean, relatively abrupt separation between the two.

The blades 19 are accurately fitted to the blade holders 15 while the latter are off the perforator roller 12 so as to provide a particular pitch diameter of the blade cutting teeth relative to the axis of shaft 13. In practice, a plurality of blade holders could be set up in advance with respective blades providing different pitch diameters and, when necessary to switch the perforator rollers from one pitch diameter cutting blade to another, it is merely necessary to dismount the existing blade holders 15 from sleeves 14 and attach thereto other holders having blades already prefitted for the new desired pitch diameter.

It should be noted at this point that the respective blades 19a to 19d of FIG. 2 include short corner blades 19y shaped to provide a slanting line of perforations `y` joining the perforations a and d of the top layer T' to those b and c of the bottom layer B'. These slanting lines of perforations `y` ultimately appear in the finished bag (FIG. 13) as trimmed corners and give thereto a very neat, clean look.

The corner blades 19y can be separated from or integral with respective ones of the other blades 19a to 19d and when separate can be interchanged with other similar corner blades to provide differently shaped trimmed corners `y` or corners `y` of different lengths. In the latter instance, the blades 19a to 19d would be interchanged with other analogous blades of different lengths to compensate for the changed length of blades 19y if it were desired to maintain the same bag width. The sleeves 14a to 14d are themselves slidably adjustable along the length of shaft 13 so that if the bag width were being increased, sleeves 14a and 14d could be moved further apart from sleeves 14b and 14c, respectively, and a longer corner blade 19y would then be inserted between the sleeves 14a and 14b as well as between 14c and 14d. Bags of different width could of course also be produced simply by changing the length of blades 19a to 19d and without changing the distance between outer blades 19a and 19d relative to the inner blades 19b and 19c.

The corner blades 19y, when separate from the other blades, are fitted in their own holders which in turn are mounted on the sleeves 14 of the outer blades 14a and 14d.

Correspondingly, the concave and convex configuration of recess `r` and protrusion `r`' add a finishing aesthetic touch to the bag which it would lack if the line b-c were straight all the way across. It should be noted that while recess `r` has been disclosed as being arcuately concave, it could have any other desired aesthetic configuration, such as square cornered, serrated, etc. It should also be noted that an important purpose of recess `r` is functional rather than aesthetic. This is, recess `r` facilitates gripping of the bag between the user's thumb and index finger with the thumb being easily slidable between the top and bottom layers, T' and B', to open the bag. Bags of the type disclosed herein usually are relatively difficult to open and may result in a certain amount of fumbling in order to be opened. The provision of an effective opening means such as recess `r` constitutes a significant improvement over heretofore known bags of this type.

The shaft of main perforator roller 12 is vertically adjustable on stand S whereby its axis of rotation may be moved towards or away from the axis of anvil roller 11 in accordance with perforator blades of different pitch diameter being mounted on roller 12.

It was previously mentioned that the blade teeth of the perforator rollers penetrate into the resilient surface covering of the anvil rollers. In this regard, it is to be noted that the pitch circle of the blade teeth should generally be tangent to the surface of the anvil roller with adjustment being made if necessary to accommodate the thickness of the bag material W which passes between the perforator and anvil rollers. This means that the tips of the blade teeth circumscribe an arc about the axis of the perforator roller which overlaps the circular arc defined by the surface of the anvil roller about its axis. Said tips, therefore, first contact the anvil roller surface at the point that the respective arcs first intersect and said tips then progressively penetrate into the anvil roller surface generally up to the depth of the pitch circle of said teeth and then progressively depart from said surface.

In order to obtain as clean a separation as possible of said teeth from the anvil roller surface as well as from the bag material they should preferably move perpendicularly away from the anvil surface as well as the bag material into both of which said teeth have penetrated. If the blade teeth were radially disposed relative to the perforator axis, they would progressively incline towards a parallel disposition relative to the anvil surface and the bag material as said teeth rotated away from the point at which maximum penetration occurs, and such progressive inclination of the teeth would cause them to grip beneath either one or both the anvil surface and the bag material. This characteristic is manifested by the bag material being lifted away from the anvil roller surface as the blade rotates away therefrom and may result in a tearing of said material along the perforations. Furthermore, the life of the resilient material on the anvil roller may be shortened from a corresponding tearing or gouging thereof by said teeth.

The inclined arrangement of the blade as set forth herein relative to a radial line from the perforator roller axis results in said teeth pulling out of the bag material and out of the anvil roller surface along a generally perpendicular direction thereby providing a clean separation and consequently a neatly defined line of perforations in the bag material.

The main perforator roller has been shown herein as including two sets of blades diametrically opposite to each other while the final perforator roller has been shown with only one blade station. It is to be noted, however, that each perforator roller may be designed to include any number of blade stations provided that the speed relationship of the perforator rollers is correspondingly adjusted relative to the feed rollers.

The herein presented specific details of preferred embodiments of realization of the various aspects of the invention are not intended to be limitative of the scope of the claims as filed originally or subsequently by way of amendment, such details being intended to be illustrative rather than limitative of the scope of the invention, it being intended to cover within the scope of the claims all equivalents, substitutions, or modifications relative to he present disclosure which are obvious or well within the purview of one skilled in the art.

Claims

What is claimed is:

1. A perforator means for a bag making machine, comprising a perforator roller having a toothed blade operatively associated with an anvil roller for passing a bag material therebetween to effect perforations therein, said perforator roller comprising a rotary shaft having a toothed blade rigidly mounted thereon with its teeth successively extending along the axial direction of said shaft, said teeth, as seen in end view, having a pitch diameter such that the outer ends of said teeth intersect the outermost arc defined by said anvil roller, said anvil roller having an outer surface of resilient material whereby said teeth penetrate thereinto pursuant to rotation of said perforation roller relative to said anvil roller, said blade forming an acute angle with a line which interconnects the axes of rotation of said perforator and anvil rollers at the moment that said teeth first intersect said arc of said anvil roller, wherein said blade is rigidly mounted on a sleeve and said sleeve is longitudinally adjustable along the length of said shaft to either of various positions thereon, including a plurality of blades arranged in axial succession along said shaft, each blade being mounted in a separate respective said sleeve and each sleeve being axially and angularly adjustable along said shaft to either of various fixed positions thereon whereby the axial spacing between blades and the angular disposition of same relative to each other may be varied.

2. The perforator means of claim 1, some of said blades being angularly offset relative to others and including a corner blade mounted at the axial end of one said sleeve between two axially offset blades, said corner blade extending at an inclination to said offset blades and interconnecting the spaced apart ends thereof.

3. The perforator means of claim 1, said blades each being rigidly mounted in a respective blade holder which, in turn, is replaceably mounted on a corresponding said sleeve.