Opening device for thermoplastic bags

Abstract

An opening and filling device for thermoplastic bags which comprises a nozzle connected to a source of gaseous fluid such as air, the nozzle having means to hang one or more bags thereon with the mouths of the bags just below the nozzle opening and having a deflecting baffle for deflecting air from the nozzle against the rear wall of the bag so that the gaseous fluid flows down between the rear wall and the front wall of the bag to open the bag. The nozzle is adapted to have a chute connected thereto with a gate for opening and closing the chute, said gate, when in open position, engaging the mouth of the bag to hold it totally in open position.

Parent Case Text

This is a continuation-in-part of co-pending application Ser. No. 395,542, filed Sept. 10, 1973.

Description

This invention relates to an apparatus for opening and filling thermoplastic bags, and it particularly relates to an apparatus of the foregoing type which utilizes air pressure to open the bags prior to filling.

As indicated in the aforesaid parent application, bags constructed of thermoplastic material such as polyethylene, polypropylene, and the like, are ordinarily difficult to open because the thermoplastic walls have a great adherence to each other so that it is not only difficult to separate the edges or lips of the walls defining the mouth of the bag but also difficult to separate the walls themselves even when the lips have been separated from each other.

The above difficulty was effectively solved by the apparatus described in the aforementioned parent application where a pack of superimposed bags are clamped to the outer peripheral portion of a filling chute and where air is blown diagonally across the chute between the lips of each successive bag in such a manner that the air is blown over the front lip of the bag against the rear wall thereof and then passes downwardly into the bag, thereby effectively opening the bag in linear arrangement with the exit opening of the chute, whereby the opened bag receives filling material passing through the chute. This opening action is aided by the fact that the bags are clamped to the chute by a clamping plate or the like which conforms to about half the circumference of the chute whereby the bags are bent partially around the chute. This provides a lateral force which causes the lip of the front wall to initially slightly separate from the rear wall to permit entrance of the air between the lips.

The above-described apparatus, although effective for its purpose, required the presence of the filling chute during the opening operation, whereby the air stream had to be delivered diagonally across the chute from front to rear. In order to obtain maximum effectiveness, it was also necessary to clamp the bags around half the periphery of the chute.

In accordance with the present invention, on the other hand the filling chute is not required for the opening operation but may be used, if required, as an auxiliary attachment. Furthermore, the air stream does not require a diagonal path from front to rear but may be directed along the rear surface so that lateral space is saved. In addition, the bags need not be clamped in semi-circular peripheral engagement with the chute in order to obtain effective entrance of the air into the bag.

It is, therefore, one object of the present invention to provide a thermoplastic bag opening apparatus which can perform its function in a highly effective manner without the presence of the filling chute and without any particular peripheral engagement therewith.

Another object of the present invention is to provide an apparatus of the aforesaid type wherein a chute is optionally provided and wherein said chute may be equipped with either a manually or mechanically-operated means to serve both as a stop means for filler materials passing through the chute and as an auxiliary means for maintaining the lips of the bag in spaced-apart, open position during the filling action.

Another object of the present invention is to provide an apparatus of the aforesaid type which is extremely simple in construction, inexpensive to manufacture and easy to use.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following description when read in conjunction with the accompanying drawings wherein:

FIG. 1 is a side view, partly broken away in section, of a bag opening device embodying the present invention.

FIG. 2 is an enlarged sectional view of a portion of the device of FIG. 1 showing a chute assembly connected thereto.

FIG. 3 is a sectional view taken on line 3--3 of FIG. 2.

FIG. 4 is a fragmentary side view, partly in section and partly in elevation, showing a modification of the device of FIG. 2.

FIG. 5 is a fragmentary side sectional view showing another modified form of the device shown in FIG. 2.

FIG. 6 is a sectional view taken on line 6--6 of FIG. 5.

FIG. 7 is a front perspective view of a bag of the type utilized in conjunction with the present invention.

Referring now in greater detail to the various figures of the drawings wherein similar reference characters refer to similar parts, there is shown in FIG. 1 a bag opening device, generally designated 10, comprising a housing 12 having an air inlet 14, a duct 16 connected to the air inlet, and a blower (now shown) for drawing the air through the inlet 14 and blowing it through the duct 16 and through a two-piece elbow conduit 18 to a housing or chamber 20. The housing 12 has a removable cover plate 21 connected thereto by any desirable connecting means such as bolts, screws, clips or the like.

The housing or chamber 20 is arcuate in cross-sectional shape (as best seen in FIG. 3) and is provided with a flat wall 22. The upper end 24 of the housing 20 is closed and is provided with a stud 26 which extends upwardly from the closed end 24. A washer 28 and nut 30 are provided on the stud for the purpose of releasably clamping a lateral flange 32 extending from a chute 34. The flange 32 is provided with a notch (not shown) which encircles the stud to permit inter-fitting of the flange when in clamped position.

The lower end 36 of the chamber 20 is open and is defined at the rear by the arcuate wall 38 and at the front by the lower end of the flat wall 22. Depending from the lower end of wall 22 is a baffle plate 40. The plate 40 is rearwardly and downwardly curved.

Extending rearwardly from the wall 38 at the lower end of the chamber 20 is a threaded stud 42 extending through an aperture in a plate 44 which is itself connected at 46 to a bracket 48 pivotally mounted on a base plate 50 extending forwardly from the housing 12. The stud 42 is provided with a nut 52 which is adapted to bear against the plate 44. The stud 42 acts as a hanger for one or more thermoplastic bags 54 that are each provided with a front wall 56 and a rear wall 58 (as best seen in FIG. 7. Each bag 54 has an open mouth defined by a front lip 60 and a perforated edge 62 defining the rear lip. The perforated edge 62 is somewhat higher than the front lip 60 and separates the rear wall of the bag from a selvage strip 64 having an aperture 66 to receive the stud 42.

In operation, one or more bags, generally a pack of bags connected together by their selvage strips 64, are hung on the stud 42, by first removing the nut 52, bending the plate 44 backwards off the bolt, inserting the bags onto the stud 42, bringing the plate 44 back onto the stud and then applying the nut 52 to the stud and tightening it in place. The blower (not shown) is then operated to blow a stream of air through the duct 18 into the chamber 20. The air passes through the chamber 20 and through the lower end 36. As it passes through lower end 36, it is deflected by baffle plate 40 toward the rear wall of the front bag 54. Since the lip 60 of the front wall of the bag is lower than the upper edge of the rear wall, the air stream passes along the rear wall between that rear wall and the front wall, thereby fully opening the bag, as shown in FIG. 1. While the bag remains hanging and open, the filler material may be inserted by hand or by any other means into the bag. After being filled, the bag is merely pulled away by tearing at the perforated edge 62. It may then be sealed or left open as desired for the particular purpose.

In FIGS. 2 and 3 there is shown the same bag opening device as in FIG. 1, the parts being referred to by the same reference characters, but in these figures, the device has attached thereto the aforementioned chute 34. The chute 34, as described above, is attached to the flat wall 22 of the chamber 20 by means of the flange 32 held in position by stud 26 and nut 30.

The chute 34 has an inclined wall 68 and is open at its upper and lower ends. The inclined wall 68 is provided with an aperture 70 in which is pivotally positioned an elbow portion 72 of a gate plate 74 which is pivotally movable against and away from the baffle plate 40 by means of a handle 76 attached to a lever portion 78 on the outer side of the elbow portion 72. The lever portion 78 is biased toward the wall 68 by a spring 80 so that the gate 74 is normally in the closed position shown in FIG. 2. It is movable into the open position by pushing up on handle 76. Although a biasing spring 80 is illustrated, it may be omitted, especially if it is desired to bias the gate into the open position since, in that case, the weight of the gate 74 would act as its own biasing means.

The chute construction shown in FIGS. 2 and 3 has several functions: (a) it acts as a funnel for insertion of filling material into an opened bag, (b) it serves to meter the amount of filling material or prevent passage of such material when there is no opened bag in place, and (c) it serves as an auxiliary retention means whereby an auxiliary positive force is exerted to hold the mouth of the bag wide open during filling. The last two functions are provided by the gate 74 which, when in the closed position, prevents passage of filling material through the chute, and, when in open position, not only permits sucn passage but abuts against the inner surface of the lip of the front wall of the bag (as shown in dotted outline in FIG. 2) to hold the mouth in wide open position.

Automatic metering may be accomplished by connecting the handle 76 or the gate 74 directly to a crank arm or the like (not shown) which is attached to an electric motor or the like actuated by a timing mechanism (not shown) or connected to a conveyor or the like (not shown) for movement in timed relationship therewith. Another manner of automatically actuating the gate is by means of a solenoid. This latter type system is illustrated in FIG. 4 where the apparatus, generally designated 90, is similar in all respects to that shown in FIGS. 1, 2 and 3, including an air duct 92, a chamber 94 having a lower outlet end 96, a stud 98 extending through a plate 100 for hanging bags 102, and a nut 104 for holding the bags in place on the stud. The chute 106 is similar to chute 34 except it is integrally connected to housing 94 (although this is optional). A gate 108, similar to gate 74 is provided in the chute; however, the gate 108 is connected to the core 110 of a solenoid 112. The solenoid may be intermittently actuated by any desired device such as a conveyor or other feed mechanism.

FIGS. 5 and 6 illustrate a modified form of the invention and is generally designated 120. In this form, the chamber 122, similar to chamber 20, is integral with a cylindrical chute 124, being separated therefrom by a flat wall 126 having a baffle plate 128 at its lower end.

The baffle plate 128 is curved downwardly and rearwardly toward the rear wall of the outermost bag 130, the bags being hung on a stud 132 and held by a nut 134 bearing against a plate 136 in similar fashion to the structure shown in FIGS. 1-4. The lower outlet end of the chamber 122, indicated at 138, is situated above the baffle plate 128 in similar manner to outlet end 36.

Attached to the chute 124 is a bracket 140 to which is hingedly connected, as by pin 142, a yoke 144. The yoke 144 is connected to a gate plate 146. A lever handle 148 extends laterally from the gate 146. A spring 150 encircles the pin 142 and is connected to the gate 146 to bias the gate into closed position. When the handle 148 is pushed up (as shown in dotted outline FIG. 5), the gate 146 swings into the open, downward position (shown in dotted outline in FIG. 5), thereby acting in the same manner and serving the same functions as gate 74.

The air stream for opening the bags may be continuous or, more preferably, may be discontinuous or intermittent pulses dependent either on a separate standard timing mechanism (not shown) or on the actuation of a valve or pump motor by a conveyor or other feed means (not shown).

The chute may have either a round, rectangular or any other desirable cross-sectional shape, as is also true of the housing 122 and the ductwork.

Although air has been described as the gaseous bag opening means, any other desirable gas or vapor may be substituted when desired.

Claims

The invention claimed is:

1. A bag opening device comprising a chamber having an inlet for a gaseous fluid and an outlet for said gaseous fluid, hanger means adjacent said outlet for hanging thermoplastic bags in such a manner that the mouths of said bags, defined by a front wall and a rear wall, underlie said outlet, and a baffle plate depending from said chamber, said baffle plate constituting a continuation of one wall portion of said outlet and underlying said outlet, said baffle plate being curved in a manner to deflect the gaseous fluid from said outlet toward the rear wall of a bag hanging from said hanger to open said bag, a chute positioned adjacent said chamber, said chute having an inlet opening and an outlet opening, said outlet opening being adjacent said outlet from said chamber, a gate positioned for pivotal movement within said chute, said gate being pivotally connected to one wall portion of said chute and having one end thereof extending through said outlet opening of said chute, said gate being pivotally movable from a chute-closing position, wherein said gate is in an inclined position within said chute with the said one end engaging said baffle plate, to a full chute-opening position, wherein said gate abuts against the interior surface of said one wall portion of said chute with said one end underlying said one wall portion, said one end being of a length to overlie the mouth of said bag when said gate is in said chute-closing position and to engage the interior surface of the rear wall of said bag when said gate is in said full chute-opening position, and a gate-operating means connected to said gate, said gate-operating means being positioned externally of said chute and being operable to move said gate on its pivotal connection.

2. The device of claim 1 wherein said chute is separable from said chamber.

3. The device of claim 1 wherein said chute is integral with said chamber and is separated therefrom by a common wall.

4. The device of claim 1 wherein said gate operating means is a handle for manual operation of said gate means.

5. The device of claim 1 wherein said gate operating means is a solenoid actuating means.