US3386225A

US3386225A - Wrapping and heat sealing machine

Info

Publication number: US3386225A
Application number: US640423A
Authority: US
Inventors: Bengt A Arvidson; Fritz F Treiber
Original assignee: Corley Miller Inc
Current assignee: Corley Miller Inc
Priority date: 1967-05-22
Filing date: 1967-05-22
Publication date: 1968-06-04
Anticipated expiration: 1985-06-04

Description

B. A. ARVIDSON ETAL 3,386,225

WRAPPING AND HEAT SEALING MACHINE June4,1968

ori inal Filed Jan. 18, 1965 5 Sheets-Sheet 1 25 Clruidsam I'Z'reiben l fm 6261044,,

IYLl/6nibrsf- I I I Ill-II ll June 1968 B. A. ARVIDSON ETAL 3,386,225

. WRAPPING AND HEAT SEALING MACHINE 5 Sheets-Sheet 2 Original Filed Jan. 18, 1965 E Q w B .fi a??? UHH H HI IH HH I I I IUH. 4 H l hU l m I June 4, 1968 a. A. ARVIDSON ETAL 3,386,225,

WRAPPING AND HEAT SEALING MACHINE 5 Sheets-Sheet 4 0P l h l l l H".

Original Filed Jan. 18. 1965 June 1968 a. A. ARVIDSON ETAL 3,336,225

7 WRAPPING AND HEAT SEALING MACHINE Original Filed Jan 18, 1965 5 Sheets-Sheet 5 United States Patent Or 3,386,225 WRAEPING AND HEAT SEALING MACHINE Bengt A. Arvidson, Villa Park, and Fritz F. Treiber, Niles, assignors to Carley-Miller, Inc., a corporation of lo Continuation of application Ser. No. 426,300, Jan. 18, 1965. This application May 22, 1967, Ser. No. 640,423 Claims. (Cl. 53184) ABSTRACT OF THE DISCLOSURE A package wrapping and sealing machine having structure for Wrapping a package in heat-shrinkable film with overlapped section of film on the bottom of the package with means for heating localized areas of the overlapped film sections to secure the film layers together along with structure for applying heat to the film to shrink the film around the product contained in the package.

This application is a continuation of my application, Ser. No. 426,300, and now abandoned.

This invention relates to package wrapping and sealing machines and, more particularly, to such a machine for handling heat-shrinkable wrapping film.

Many different forms of wrapping machines for wrapping film about a package, such as a grocery package of meat or produce, are presently known in which a sheet of wrapping material is initially banded about the product and the package is then moved through 'a wrapping machine to complete the wrapping thereof. An example of such a machine is shown in Arvidson Patent No. 2,981,- 043, dated Apr. 25, 1961. In such a machine after completing the wrap, the package is moved onto a hot plate where overlapping sections of the film are sealed together and the package is then discharged from the wrapping machine. More recently, different films have been developed in which the film has the property of shrinking, when heated. This film has the advantage of shrinking tightly about the package and presents a stronger and better appearing package for meats and produce. However, certain problems can arise in sealing the package because of the tendency of the film to shrink upon application of heat and in certain applications care must be taken as to how the scaling is effected. Also, care should be taken not to damage the packaged material by the application of heat.

An object of this invention is to provide a new and improved wrapping and sealing machine for utilizing heat-shrinkable films.

Another object of the invention is to provide a wrapping and sealing machine which utilizes heat-shrinkable films in which heat is applied to the film for causing shrinking thereof only as required to provide a minimum amount of heating of the product within the package and without directing substantial amounts of heat to the surrounding room area, since the equipment frequently would be used in a refrigerated area.

A further object of the invention is to provide a package wrapping and sealing machine in which a product is sealed and immediately conveyed to a heat tunnel where heated air is directed against the package to accomplish over-all shrinking of the film to form a tight package.

An additional object of the invention is to provide a package wrapping and sealing machine which utilizes heat-shrinkable film in which the film is shrunk about the package by intermittently directing hot air against the package only at the time that a package is properly positioned.

An additional object of the invention is to provide a machine as defined in the preceding paragraphs in which 3,386,225 Patented June 4, 1968 w CC initial tacks are made in the overlapping sections of the film by limited application of heat prior to final sealing thereof to localize the tendency of the film to shrink, whereby over-all application of heat to the overlapping sections will not result in the overlapped sections shrinking away from each other and thus preventing an effective sealing of the package.

Further objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1 is a side view in elevation of a first embodiment of the wrapping and sealing machine;

FIG. 2 is a section on an enlarged scale and taken generally along the line 2--2 in FIG. 1 and with the presser members lowered;

FIG. 3 is 'a perspective view of a package looking toward the bottom thereof after the initial tacks have been made in the overlapped sections of the wrapping material and prior to final sealing thereof;

FIG. 4 is a section, on a further enlarged scale, taken generally along the line 4--4 in FIG. 2 and at the level of the sealing station of the machine;

FIG. 5 is a section through a heat exchanger and taken generally along the line 55 in FIG. 4;

FIG. 6 is a fragmentary vertical section taken generally along the line 6-6 in FIG. 1 and on an enlarged scale;

FIG. 7 is a vertical section taken generally along the line 77 in FIG. 6;

FIG. 8 is a view similar to FIG. 1 of a second embodiment of the invention and with an end of the machine omitted;

FIG. 9 is an end elevational view of the structure shown in FIG. 8 looking toward the right-hand end thereof;

FIG. 10 is a side elevational view of a third embodiment of the invention and with an end of the machine omitted; and

FIG. 11 is an end elevational view of the structure shown in FIG. 10 and looking toward the right-hand end thereof.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail an embodiment of the invention together with modifications thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

The wrapping and sealing machine, as shown in the first embodiment illustrated in FIGS. 1 to 7, comprises a basic frame, indicated generally at 10, having a pair of supporting legs 11 and 12 at each side thereof with those at one side being shown in FIG. 1. An overhead frame, indicated generally at 13, is positioned above the main frame in spaced relation by a pair of support brackets 14 and 15 at each side with the brackets being shown at one side in FIG. 1. The frame 13 houses an overhead conveyor mechanism, in the form of a series of spaced paddles 16 spaced lengthwise along the length of the machine, with these paddles having a four-way motion to descend behind packages, advance the packages along the length of the machine to the next station and then elevate to a position over the packages for return to an initial position. This structure is shown only generally herein and reference may be made to the Arvidson patent, No. 2,981,043, for a more detailed disclosure of these paddle members and the operating mechanism therefor.

The wrapping machine has a loading station 20 at the entry end thereof and at the left in FIG. 1, where a package initially banded with a sheet of wrapping material by an operator is placed in position to be advanced to an initial wrap station 21. The package is advanced by a conveying mechanism embodying a pair of spaced chains one of which is shown at 22 passing about sprockets 23 and 24 at each side and having sequentiallyspaced pusher members 25 extending therebetween. Again reference may be made to the aforesaid Arvidson patent for a more detailed disclosure of this structure. At the initial wrap station 21, a pair of fold-down wings, located one at each side of the wrapping machine, are caused to move downwardly past the ends of a package to sweep the projecting flaps of wrapping material down to a vertical position extending downwardly from the package. One of these wings is shown at 26 in FIG. 1. A package is then advanced from the initial wrap station 21 to a bottom plow station 27, shown particularly in FIG. 2, wherein the downwardly extending flaps of wrapping material are folded underneath the package into overlapped relation as shown in FIG. 3. This is accomplished by the

stationary plow members

28 and 29 which are angled toward each other, as shown in FIG. 2, to progressively plow under the flaps of wrapping material. The formation of the wrap is detailed more specifically in the aforesaid Arvidson patent. As shown in FIG. 3, an operator has initially wrapped

film sections

30 and 31 about the package to form an initial band and the flaps 32 and 33 are plowed down and under at the

stations

21 and 27, respectively.

The package has been advanced from the station 21 to the station 27 by means of the left end paddle member 16, which as shown in FIG. 1, is in advanced position, and when retracted is to the left overlying station 21 to come down to the rear of a package and advance it. As in the Arvidson patent, the

bottom plows

28 and 29 are mounted on

adjustable side members

35 and 36, respectively, which can be moved toward and away from each other to adjust for the size package being wrapped and sealed. Following the bottom plowing station 27, the package is advanced, by the overhead conveyor mechanism, to a sealing and film-shrink station 38 having a hot plate 39 of a size to have the entire package disposed thereabove. The package does not directly contact the hot plate because of the utilization of an endless belt 4-0 of heat-resistant, slippery material, such as Teflon, which extends through the sealing and shrink station 38 and therebeyond to a cooling station 41. The belt extends across the width of the hot plate and is supported for free movement by a roller 42 at the entry end of the station 38 and a roller 43 at the exit end of the machine. The roller 43 is rotatably supported by a pair of arms 44 and 45 extending outwardly from the main frame of the machine.

With the endless belt mounted to move with a package, any tendency for a package to stick to the hot plate is avoided and the package can be simply advanced intermittently by the overhead conveyor mechanism.

With certain heat-shrinkable films, it is quite possible for the initial applicaton of heat over the entire surface of the package to cause such shrinking of the film as to draw the film out of overlapped relation, so that no sealing can be made. In order to avoid this, the hot plate can have a series of ribs 47 at the front end thereof which cause spaced sealing tacks across the width of the package to form areas of bonding. These lines of tacking are shown in the package in FIG. 3 at 48. When the package is moved to a position entirely over the hot plate, the shrinking will not be massive, but a complete seal will be made.

The sealing of the package is enhanced at station 38 by presser means which presses a package down against the belt 48 and indirectly against the hot plate 39. This pressure is important to press the lms together for a good strong seal and also creates sufficient friction on the underside of the package to minimize shrinking of 4 the film because of the heat. Also, the pressure causes the heat to penetrate the film faster and effect a seal before excessive shrinking can occur.

The presser means embodies a pair of

presser members

58 and 51 of resilient material which are shown in engagement with a package 52 in FIG. 2 and similarly positioned in broken lines in FIGS. 6 and 7. The presser members and 51 are normally mounted at a distance above the sealing station and are movable downwardly under the influence of gravity to engage against the top of a package which may have a height within a substantial range. The structure for operating each of the presser members is identical and the structure for operating the presser member 51 is shown particularly in FIGS. 6 and 7. The presser member 51 is mounted for up and down movement by a pair of parallel arms 53 and 54 pivoted at 55 and 56, respectively, to a mounting plate 57. The other ends of the parallel arms are pivotally connected at 58 and 59 to a vertically extending bar 66 which carries a generally horizontal plate 61 at the lower end thereof extending lengthwise of the machine. This plate mounts a second plate 62 therebeneath spaced therefrom with the plate 62 being yieldably mounted on plate 61 by movable bolts 63 and urged to a position away from the plate 61 by means of springs 64 surrounding the bolts and positioned between the plates. The presser member 51 is secured to the plate 62. The elevation of the presser member is controlled by a cam 65 mounted on a shaft 66 to which a gear 67 is also secured. A cam follower roller 68 is positioned above the cam and in engagement therewith and is mounted on a follower arm 69 pivoted to the frame at 70 whereby the arm 69 rocks back and forth as controlled by the cam 65. An end of the arm 69 is connected by a link 71 to the upper parallel arm 53. Thus, upon rotation of the cam 65, the follower roller 68 can move from the position shown in FIG. 7 onto the low of the cam shown in broken line which permits descent of the presser member by gravity. Upon continued rotation of the cam, the follower roller will be elevated to elevate the presser member.

The drive for operating the presser members and the overhead conveying mechanism is obtained from a motor driven gear reduction unit 75 shown in FIG. 1 which drives a chain 76 engaging a sprocket on a shaft 77 which has a sprocket which drives a vertically-extending chain 78. The chain 78 drives a sprocket 79 mounted on a shaft 7% also mounting a gear 80. The gear 80 meshes with the gear 67 to drive the operating cam 65 for the presser member.

The drive timing causes the

presser members

50 and 51 to be lowered against a package when the overhead conveying mechanism is inactive for advance of a package.

Means are also provided at the station 38 to shrink the film tightly about the package. This is accomplished by a pair of heat exchangers and 86 located at opposite sides of the hot plate 39 which intermittently direct charges of heated air against the package and partially against the top thereof whereby the heat will cause the film to shrink. Each of these heat exchangers are identical and the heat exchanger 86 will be more particularly described. The heat exchanger 86, as particularly shown in FIGS. 4 and 5, embodies a casing forming an enclosure, with a top wall 87 and a bottom wall 88. A heating plate 89 is disposed at an intermediate level with in the casing whereby air entering through an inlet 90, shown in FIG. 2, will pass into the top part of the casing and back and forth through a labyrinth section 91 and then descend through opening 91a to a location beneath the heating plate and back through the labyrinth for emission through a pair of rows of

air exhaust passages

92 and 93. The passages 92 are disposed at an angle to direct hot air towards the lower side of the package and the passages 93 are disposed to direct air more toward the top of the package. To prevent heat from contacting emitted from the heat exchanger casing only when a package is located at the station. One charge of air is contained within the casing and a succeeding charge of air will cause emission of a heated air charge from the casing, with said succeeding charge of air being held in the casing for heating thereof. This results in a minimum wastage of heat, since none is emitted except when a package is present. A bellows 96 is mounted to the frame by a bracket 97 with the bellows having an air inlet 98 with a one-way check valve 99 preventing egress of air from the bellows. Upon the compression stroke of the bellows, air is directed through the line 95 and the heat exchanger through a one-way valve 100 which prevents entry of hot air from line 95 back into the bellows on the expansion stroke of the bellows. The bellows is operated in timed relation with the package conveying mechanism and the presser members by a crank 101 mounted on the cam shaft 102 of the machine. The crank drives a link 103 connected to a lever 104 pivoted at one end 105 to the frame and connected at its other end 106 to the bellows. The cam shaft 102 is driven from the drive shaft 77, previously referred to, by a chain 107.

The heated air strikes the lower part of the package and then flows up and around it. As a result, the force of the air blast is not directed against the product within the package, but against a tray or the like in the package and on which the product rests. The heated air will then flow up and over the top of the package to induce some shrink, but there will be no damage to the product.

The

heat exchangers

85 and 86, as shown in FIG. 2, are mounted on the

adjustable members

35 and 36, which carry the bottom plows, whereby the heat exchangers can also be spaced relative to each other, dependent upon the package size.

A flexible heat-proof curtain 110 is associated with each of the heat exchangers and extend out a short distance toward the package and across the end of the heat exchanger to aid in preventing loss of heated air.

In the embodiment of FIGS. 8 and 9, the structure corresponding to that shown in the embodiment of FIGS. 1 to 7 is given the same reference numeral with 200 added thereto.

In this embodiment, the shrinking of the film occurs at a shrink station 130 following the sealing station 238. The shrink station is defined by a tunnel having a top wall 131 and side walls 132 and 133, with the tunnel being supported from the arms 244 and 245 by suitable attachment thereto. Heated air is delivered to the tunnel by

heat exchangers

285 and 286 of the same construction as the

heat exchangers

85 and 86 shown in the first emobdiment and with the heat exchangers each fitting within a suitably shaped opening in the side walls 132 and 133, respectively, of the tunnel. Air under pressure is supplied intermittently to the

heat exchangers

285 and 286 through a pair or

air lines

136 and 137 which connect to the outlet side of the bellows 296 and correspond to the line 95 of the first embodiment. The tunnel confines the hot air delivered thereto for more uniform and close contact thereof with the wrapping film and prevents the dilution of this air by surrounding cool air. In order to further maintain the heat within the tunnel, the open ends there-of are each closed by a slitted curtain with the curtain 138 being shown at the exit end of the tunnel .to substantially close off the tunnel while permitting ingress and egress of a package. In this embodiment, the overhead conveyor mechanism does not operate beyond the end of the main frame of the machine and the conveying of the package to and from the tunnel is obtained by a drive of the belt 240. This intermittent drive is obtained from the cam shaft 302 driving a crank 140 connected to a rack 141 which is movable within a housing 142 and engageable with a pinion 143 fixed to the shaft mounting the belt supporting roller 242. The drive to the roller further includes a conventional one-way clutch (not shown) for obtaining one direction of rotation of the roller.

The third embodiment is shown in FIGS. 10 and 11 and parts thereof corresponding to those shown in the previous embodiments are given the same reference numeral with 300 added. In this embodiment the over-all construction is the same, however, continuous heated air is supplied to the tunnel, rather than intermittent heated air. In this form, a motor-driven blower, such as a double centrifugal unit, is mounted beneath the main frame and embodies a motor driving the

blowers

161 and 162. The blowers are connected to

air lines

163 and 164, respectively, which extend to nozzles 16 5 and 166,

respectively, fitted through the

walls

432 and 433 of the tunnel. These nozzles each have a long, narrow slit 169 for emitting elongate streams of air lengthwise of the tunnel. The .air, in its passage to the

nozzles

165 and 166, is heated by suitable

electric elements

167 and 168, positioned within the air lines.

In this embodiment, the emitted air is kept low within the tunnel to avoid substantial contact with the product in the package. The air, being hot, will normally rise and pass over the top of the package to induce further shrinking. Keeping the air l-ow results in a minimum of concentrated heat on the top of the package, to avoid a hot spot which would be detrimental to fresh meat or produce.

From the foregoing, it will be seen that structures have been provided which accomplish optimum sealing of a package wrapped with heat-shrinkable film and which provide for shrinking of the film about the package. Maximum utilization of heat is obtained, due to minimum loss of heated air to the surrounding atmosphere and without harmful effects on the product contained in the package.

We claim:

1. A machine for wrapping and sealing a package in heat shrinkable film comprising, means for wrapping a package with film with overlapped sections of film on the bottom of the package, means defining a bottom sealing station for sealing together said overlapped sections of film by the application of heat and having means at the entry end of said station for making spaced apart tacks in said overlapped sections to hold the sections in overlapped relation prior to application of heat on the entire bottom of the package, and means defining a shrink station after the bottom sealing station to apply heat to the film and shrink the film tightly against the package.

2. A machine as defined in claim 1 including a pair of heat exhangers at said shrink station located at opposite sides of the package path, each of said exchangers having air outlets directed toward only the lower part of a package, conveying means for intermittently advancing a package to said shrink station, and means operable in timed relation with said conveying means for intermittently blowing a blast of air through the heat exchangers and out of said outlets against a package when located opposite said outlets.

3. A machine as defined in claim 2 wherein each heat exchanger is of a size to hold a charge of air sufiicient for one blast whereby one blast can be heated and then discharged in the succeeding cycle.

4. A machine as defined in claim 2 wherein said means for blowing air comprises a bellows and hoses connecting said bellows to said heat exchangers.

5. A machine as defined in claim 2 wherein said machine has wrapping members adjustable toward and away from each other for handling different size packages, and said heat exchangers being mounted on said members for simultaneous adjustment with said members for different package sizes.

6. A package wrapping and sealing machine utilizing shrink film in Wrapping comprising, a station for sealing overlapped sections of film, means for intermittently conveying a package to and from said station, a hot plate at said station, a belt of slippery heat-resistant material overlying said plate, means rotatably mounting said belt to overlie said plate and to be movable with a package advanced by said conveying means, presser means positioned over said plate to press a package against the belt and hot plate to make a fast seal with minimum shrinkage of the film, said hot plate having a front section thereof formed with raised ribs whereby localized heat is applied to said package to form tacks in said overlapped sections prior to final sealing by said hot plate whereby shrinking is localized during said final sealing.

7. A package wrapping and sealing machine having means for wrapping a shrink film about a package with overlapped film sections at one face of the package and having a package sealing station, a hot plate at said station, a belt of heat-resistant slippery material overlying said plate, means mounting said belt for movement with a package over and along said hot plate, a pair of heat exchangers located one at each of opposite sides of said hot plate, each of said heat exchangers having a casing for storage of air therein, a heating element in each casing for heating the air, a series of air outlets from each casing directed toward the space overlying the hot plate to direct heated air onto a package, means for directing intermittent blasts of heated air from said casings comprising, a bellows, hoses connecting said bellows to said casings, and means for compressing said bellows when a package is at said station.

8. A machine for sealing packages having a shrink station, a tunnel at said shrink station having a top wall and side walls with partable means at the ends for entry and egress of packages, a pair of heat exchangers each having a casing positioned one in each or" said side walls and of a height less than half the height of the tunnel, air exhaust passages from each casing located beneath the middie of the casings to direct heated air only into the lower part of the tunnel, each of said heat exchanger casings storing air therein for heating thereof, an intermittently compressible member with an outlet connected to each of said casings by conduits, and means for compressing said member when a package is in said tunnel.

9. A machine for wrapping a package in heat shrinkable film comprising, means for wrapping a package with film with overlapped sections of film on the bottom of the package, means for sealing together portions of said overlapped sections of film by the application of heat to hold the sections in overlapped relation and the film about the package including spaced apart heatable members to underlie spaced portions of a package bottom and apply 10- calized heat thereto, means positioned between the members and package to prevent direct contact therebetween, and means operative after sealing portions of said overlapped sections to apply heat to the film disposed above the bottom of the package and shrink the film tightly against the package.

18. A machine as defined in claim 9 wherein said heat applying means comprises a tunnel to retain air therein and having a pair of heated air outlets in the side walls thereof directed only toward the lower part of the package to reduce the direct application of heat against the product in the package.

References (fitted UNITED STATES PATENTS 2,880,522 4/1959 Rollins 53---184 XR 2,904,943 9/1959 Dreyfus et al. 53--184 XR 2,981,043 4/1961 Arvidson 53-206 3,156,812 11/1964 Forman et al 53-30 XR 3,164,939 1/1965 Burke 53-184 XR 3,222,800 12/1965 Siegel et al. 53184 XR WILLIAM W. DYER, 111., Primary Examiner.

GRANVILLE Y. CUSTER, Examiner.