US2486761A - Method and apparatus for working sheet material - Google Patents

Description

1 1949 F. B. PFEIFFER 2,486,761

METHOD AND APPARATUS FOR WORKING SHEET MATERIAL Filed Jan. 30, 1945 ATTO R N EY Patented Nov. 1,

METHOD AND APPARATUS FOR WORKING SHEET MATERIAL Fred B. Pfeifler, Akron, Ohio Application January 30, 1945, Serial No. 575,297

11, lines thirteen to twenty-four inclusive, and to' Figs. 2, 7, 8 and 9 of the drawings accompanying said application it will be seen that edge portions of a blank of sheet material are clamped between two non-collapsible clamps during the beginning of the stretch-wrapping operation and that dur-' ing the operation of stretching the sheet material about an object being wrapped that the noncollapsible clamps release the edge portions of said blank of sheet material and that said edge portions are caught on or by inwardly moving members or crimpers whereby the said edge portions are drawn inwardly to complete the packaging of an article being wrapped.

I have found that a softclinging sheet of wrapping material will slip little, if any, on said crimpers and that a hard, stiff material will slip some degree and accordingly u'nuniform results are obtained from wrapping materials of different characteristics. The present invention overcomes such variations by positively holding said edge portions as they are carried inwardly. The novel method may be practiced in several ways all of which employ the principle of stretch-wrapping wherein the means holding the edges or portions of the edges of a sheet or blank of wrapping material being used are moved or drawn inwardly thereby utilizing substantially the entire area of said sheet or blank in covering the article being wrapped or covered. Although the preferred form of the invention illustrated in this application is shown in connection with stretch-wrapping it will be obvious to those familiar with the art that the methods and apparatus are novel and useful for other purposes and it is'my intention that the invention be limited only by the claims.

The foregoing and other objects, features and advantages of the invention will readily appear from the following description in connection with the accompanying drawings, wherein the invention is shown merely by way of illustration and wherein, I

1 is a top plan view of another form of a 13 Claims. (CI. 18-19) method and in Fig. 1 shown in closed position in the process of wrapping a bottle;

Fig. 3 is a cross-sectional view taken on line 3-3 of Fig. 2;

Fig. 4 is an enlarged fragmentary detailed view showing the vacuum connecting means for the holding members;

Fig. 5 is a cross-sectional view taken on line 5- 5 of Fig. 4;

Fig. 6 is a crossesectional view taken on line 6-6 of Fig. 5; showing the vacuum line connection to the holding member;

Fig. '6a is a perspective view of a wrapped bottle as it appears after removal from the apparatus shown in Fig. 2, shown on a smaller scale;

Referring to Figs. 1, 2 and 3 it will be seen that a supporting frame I00 rests on a base I 0| on which a motor I 02 and a gear reduction drive I03 are supported. Frictionally attached to the drive I03 by a frictional clutch I05 is a crank shaft I06.

The clutch I05 is provided with an engagement means I01. Rotatably attached to the crank .shaft I06 are arms I08 and said arms are pivotally attached to adjustable toggle arms I09 and H0 which pivot on movable pivot pins II I and fixed pivot pins 2 rigidly attached to the frame I00. Arms I09 are adjustable by means of a turn buckle I13 and are pivotally attached to sheet material channeled holding members support frames H4 by pivot pins II5 which are rigidly attached to recessed top portion I22. The bottom of said recessed portion is formed with a knurled or channeled surface I23 whereby air may be withdrawn from between a sheet of material I24 and said surface I23 thus making substantially the entire area of said surface available for atmospheric pressure to retain said'sheet material in contact with said member H9 during the period the vacuum is maintained. Members I20 are connected by means of a flexible hose connection I2 0. The opening through said hose connection with the duct I20 through a nipple HI and said nipple has a head portion I32 adapted to retain said nipple in holes I33 formed through the bottom of said members II'I and is held in airtight relation to members I II by means of washer I34 and lock nut I35. The flexible member I30 is retained in airtight relation with member I3I by means of hose clamps I36. A vacuum line I31 is attached to member I30 by any satisfactory means not shown. Attached to frame I by means of a support member MI is a stop and positioning device I40. Member I40 is attached to the member MI by screws or any other means found satisfactory. The member I is attached to the frame I 00 by means of bolts I42. It is to be understood that the invention contemplates adjustment of the device I40 in various positions to accommodate different sizes of objects being operated upon and for this purpose slots may be provided in member I00 as well understood by those familiar with the art. A small air exit channel I45 is provided in the edge portion of 'the member II'I whereby air trapped between the object being wrapped and the wrapping material is allowed to escape as will hereinafter be explained.

The operation of this form of the invention will now be briefly described in connection with the wrapping of a bottle 85a, however, it is to be understood that by modification of the shape of the holding members Ill and its inserts II 9 that various objects of different sizes and shapes may be wrapped. The operation of wrapping is begun with the device in the open position shown in Fig. 1 by the operator manually laying a blank of heat-softenable and heat-scalable wrapping material I24 of suitable size on the holding members I" and then connecting the vacuum line I31 by means of a valve not shown. This causes the wrapping material J24 to be held firmly at its edge portions, said edge portions being drawn by differential fluid pressure into the recessed portion I22 of the insert H9 where said wrapping material is pressed against the knurled surface I23 as best shown in Figs. and 6. Next the blank of material I24 is heated by a blast of hot air froma blower, not shown, or by heat from any source of supply. When the wrapping material I24 becomes soft enough for the stretchwrapping operation the operator manually presses the bottle 85a with the'bottom of said bottle first in contact with the said wrapping material directly over the stop and positioning device I 40. The operator then thrusts the bottle downwardly until the bottom of the bottle rests in position in the device I40 as shown in Fig. 2 with the material I24 stretched about the bottom of the bottle. Since many thermoplastic materials are thermoelastic, by which is meant that they will return to their unstretched condition when heated it is necessary when the sheet I24 is such a'thermoplastic material for the operator to hold the bottle 85a in position in the rnember I40. Of course automatic gripping means may be provided on the member I40 if found desirable. In the present specific illustration the operator holds the bottle in position by grasping it on its bottom portion under the frame I" so that the operators hands and arms are out of the way of the closing jaws of the said frame. The automatic features of the device are next set in motion by the operator closing a switch, not showmwhich conducts electrical current to the motor I02. The motor through the gear drive I03 and members I04 and I05 and I01, actuates the crank shaft I06 which starts from the position shown in dotted lines in Fig. 3. As the crank arm approaches its upward position the arms I08, I09, and H0 move to carry the leaves or jaws of the frame H1 in a hinging motion about the hinge pin H6 until the said crank arm reaches its upwardmost position when the edges of the inserts II9, on which the edge portions of the wrapping material I24 are firmly held, are pressed firmly together catching said wrapping material I24 between them causing the wrapping material to fuse or heat seal on a relatively narrow line following the contour of the closed members H9. The operator may set the automatic mechanism in motion during the time the operator is pressing the bottle downward against the wrapping material I24 in which case the operator will synchronize his motions with that of the device by first pressing the bottle downward and then reaching under the frame II! and pulling the bottle downward against the member I40 as the members II'I fold together. It is to be understood, as can be seen by reference to Fig. 3, that the inserts II9 protrude a short distance above the edges of the channel in the frame 1. In this operation the positioning device I40 has been adjusted to a height on the frame I00 that the holding device III will pass over the top of the bottle a held in position on said device. The contour of the frame III has also been designed to conform to the shape of the top of the bottle 85a with sufficient clearance to avoid excessive stretch of the wrapping material as said wrapping material is stretched over the said bottle as the surfaces of the holding members H9 move into contact with each other as just described. By reference to Fig. 2 it will be seen that the wrapping material is stretched like a tent from the hinge pin portion of its holding means to the bottom of the bottle and that from the hinge pin portion of the frame I I3 upward the wrapping material is fused together a distance away from the bottle with the result that a substantial volume of air is enclosed between the wrapping material and the bottle. Many thermoplastic wrapping materials such as materials now commercially available under the trade names of Pliofilm Koroseal and Kodapak will shrink back when heated and stretched and the stretched material remains heated. Since in the present operation there may be residual heat left in the wrapping material which would cause it to shrink back against the bottle. or if not sufiicient residual heat remains in the wrapping material after the wrapping operation it may be desirable to again heat the wrapping material to cause it to shrink back against the bottle in order to get a neat package; or if a wrapping material has been used that is normally elastic as thin vulcanized rubber with provisions for heat or pressure sealing it between the memhers I II, in any of these cases it will be seen tha air would be trapped between the bottle and the wrapping material which would be objectionable for obvious reasons. The present invention overcomes such trapping of air by the provision of a small aperture through the fused or sealed edge portion of the wrapping material which will be understood by reference to Figs. 1, 2 and 3 wherein is disclosed a small groove I45 cut across the member H9 in such manner as to cause the wrapping material I24 to be drawn into said groove with the result that the entire portion of said material held on the members I" will be fused or sealed together except over the grooves I45 whereby a small air escape passage is provided for the outward flow of air from between aster/cl,

the wrapping material the bottle [as the wrapping material shrinks back against the bottle to form snug fit there against. After this shrinkage has taken place this air escape passa e may be sealed by pressing its edges together and heat sealing it or in any other manner found satisfactory. After the bottlehas been entirely enclosed within the wrapping material I24 it is released from the wrapping mechanism as the crank shaft I06 returns to its lowest position thus reversing the motion of the mechanisms parts as will be readily understood by those familiar with mechanical motions; It will also be understood that the turn buckles H3 function to ad- Just the pressure between the members H1. Obviously stopping mechanism at the end of a cycle of the machine's motion may be provided and the hinge-like motion of the members ill! and H9 can be accomplished by variousmechanical arrangements In describing the preferred form of the present invention I have referred to the sheet wrapping material as thermoplastic and have also referred to commercially available sheets by their trade names of Pliofilm Koroseal" and Kodapak," however, I do not intend my invention to be limited to the use of these or any other particular material. Obviously a thin sheet of stretchable wrapping material would work satisfactorily without the method step of softening. Also that thin wrapping material that would become softened and stretchable with a spray of water, alcohol or other substance, would not require the heat treatment referred to in some cases but would require its own special softening treatment according to the material being used. It is pointed out here, however, that one material found satisfactory for stretch-wrapping in all of the forms of the invention described in detail in connection with the apparatus shown herein is a thin sheet of rubber hydrohalide such as that disclosed in the Calvert Patent No. 1,989,632 to which reference is made for a disclosure of one suitable wrapping material for use in practicing this invention.

From the foregoing it will be evident that I have provided novel method steps and apparatus for' covering various articles. The invention .is susceptible of numerous modifications other than those specifically described and illustrated, and the right is herein reserved to make such changes as fall within the scope of the appended claims without departing from the spirit of the invention.

This application is a continuation in part of application Serial No. 193,214, filed February 28, 1938, and a substitute for application Serial No. 407,083, filed August 15, 1941, now abandoned.

I claim:

1. Packaging apparatus of the class described, comprising 'a supporting frame in which ismou'nted a crank shaft rotatably connected with arms which in turn are pivotally attached to toggle arms, said toggle arms being connected to said supporting frame through movable pivot pins and fixed pivot pins, said toggle arms being -'pivotally attached to sheet material channeled holding means support frames, said support frames being supported by a hinge pin in a similar manner to the leaves of a' hinge, the channel ofsaid channeled frame containing a vacuum sheet ma terial holding members in the form of inserts "whose top portions are formed with a shallow vacuum chamber" whereby a substantial area of said vacuum chamber iseiiposed to'a sheet of t ve s: w re when wa e is in tion on said holding members, said channeled frames being shaped to conform to theshape of and to hold together over at least a part of an ob- Ject being enclosed in said sheet wrapping material in a packaging operation.

2. A wrapping unit in the form of a clamp for holding a sheetof wrapping material and defining an opening to accommodate the object to be wrapped, said clamp having a substantially continuous gripping surface extending around the entire perimeter of the opening and comprising a pair of complementary sections arranged in hinged relation, said sections being movable to an open position for holding the sheet in substantially flat condition and being movable to a closed position for holding the sheet in folded condition with all its edge portions brought together in opposed parallel relation for extended contact in a single plane.

3. A wrapping unit in the form of a clamp for holding a sheet of heat-sealable and thermostretchable wrapping material and defining an opening to accommodate the object to be wrapped, said clamp having a substantially continuous gripping surface extending around the entire perimeter of the. opening and comprising a pair of complementary sections arranged in hinged relation, said sections being movable to an open position for holding the sheet in substantially flat condition to permit the stretching of the sheet to partially enclose the object to be wrapped and being movable to a closed position after such stretching of the sheet to bring all its edge portions into heat-sealing engagement to complete the enclosure of the object;

4. A wrapping unit according to claim 2, wherein the gripping surface of the clamp is formed with a vent to permit the escape of air from within the package resulting from the wrapping operations described.

5. A wrapping unit according to claim 2, wherein the gripping surface is created by vacuum means incorporated in the clamp.

6. A wrapping unit according to claim 2, wherein the complementary sections are made to approximate the shape of the object to be wrapped.

7. A wrapping unit in the form of a clamp for holding a sheet of wrapping material, said clamp being equipped with vacuum means for exerting a gripping action on the sheet and formed with a vent to permit the escape of air from within the package created by a complete enclosure of the object in said wrapping material.

8. A wrapping unit in the form of a clamp for holding a sheet of heat-scalable wrapping material, said clamp being formed with a vent to permit the escape of air from within the package created by a complete enclosure of the object in said heat-sealable material.

9. In the art of packaging, the method which consists in clamping a sheet of heat-sealable and thermostretchable wrapping material in substantially flat condition by a gripping action exerted thereon around its entire perimeter so as to hold fast to all the edge portions thereof, stretching the sheet while thus clamped to partially enclose the object to be wrapped, and then bringing the edge portions of the sheet together in opposed parallel relation for extended lieat-sealing 'contact substantially throughout their entire extent to'completely enclose the object.

10. A method as 'in claim 9, wherein the heatfsealin engagement 'oftiie edge portions of the sheet is complete except for 'a small vent left for thetrapped from within the 11. A method as in claim 9, wherein the heatsealing engagement of the edge portions of the sheet is complete except for a small vent left for bleeding the trapped air from within the package, and thereafter'closing up said vent by heat-sealing to render the package air-tight.

12. A wrapping unit in the form of a clamp for holding a sheet of wrapping material and defining an opening to accommodate the object to be wrapped, s aid clamp having a substantially continuous gripping surface extending around the entire perimeter of the opening and comprising collapsible and extensible sections, said sections when extended holding the sheet in substantially flat condition and when collapsed holding the sheet in folded condition with all its edge portions brought together in a common plane.

13. A wrapping unit in the form of a clamp for holding a sheet of heat-sealable and thermostretchable wrapping material and defining an opening to accommodate the object to be wrapped, said clamp having a substantially continuous gripping surface extending around the entire perimeter of the opening and comprising 8'- collapsible and extensible, sections, said sections when extended holding the: sheet in substantially flat condition to permitthestretching of the sheet to partially enclose the object to be wrapped,

and when collapsed after such stretching of the sheet holding all its edge portions in heat-sealing engagement to complete the enclosure of the object.

FRED B. PFEIFFER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Snyder Feb. 29, 1944

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