US3488912A

US3488912A - Packaging machine and method

Info

Publication number: US3488912A
Application number: US679092A
Authority: US
Inventors: Donald K Christian
Original assignee: WR Grace and Co
Current assignee: WR Grace and Co
Priority date: 1967-10-30
Filing date: 1967-10-30
Publication date: 1970-01-13
Anticipated expiration: 1987-01-13
Also published as: DE1804904A1; FR1590297A; JPS492158B1; GB1197369A

Description

Jan. 13, 1970 D. K. CHRISTIAN 3,488,912

PACKAGING MACHINE AND METHOD Filed Oct. 30, 196'? 6 Sheets-Sheet l Invemor Donald K. Chris I;

y WM'M 19 Afforney 13, 1970 D. K. CHRISTIAN PACKAGING MACHINE AND METHOD 6 Sheets-Sheet 2 Filed Oct. 30, 1967 OOOOOOOOO OO-OOOOOO 000000 Inventor Donald K. Ch

ri flan mma D. Attorney Jam 1970 0. K. CHRISTIAN 3,488,912

' PACKAGING MACHINE AND METHOD Filed Oct. so, 1 96'; e Sheets-Shet 5 Inventor AHorn D. K. CHRISTIAN PACKAGING MACHINE AND METHOD Jan. 13, 1970 6 Sheets-Sheet 4 Filed Oct. 30;. 1967 FIG.

Jan. 13, 1970 0. CHRISTIAN v I 3,4

PACKAGING MA CHINE AND METHOD Filed Oct. 30, 19s? s Sheets-Sheets FIG. 5

Inventor I I. Donald K. Chgig kian y Afforney Jan, 13,1970 0. K. 'CHR'ISTIIAN 3,488,912

' PACKAGING MACHINE AND METHOD Filed 001:. 30. 196'? 6 Sheets-Sheet.6

FIG. 6

INVENTOR DONALD K. CHRISTIAN United States Patent US. Cl. 5328 9 Claims ABSTRACT OF THE DISCLOSURE The film on two spaced apart rolls of heat sealable packaging film is sealed together intermediate the two rolls. A stream of air cools the seal and simultaneously advances the sealed film ahead of an article to be packaged so that the article does not bear directly against the film seal. As the article is advanced, the film from one roll covers the upper portion of the article and the film from the other roll covers the lower portion. When sufficient film has been fed from the rolls the unsealed portions around the article are sealed together thus forming a complete package.

The invention relates to a method and apparatus for packaging articles in heat scalable and shrinkable film. In particular, the invention relates to a packaging method and apparatus in which two rolls of heat scalable and shrinkable thermoplastic film are used to continuously and automatically wrap articles such as boxes of candy, record albums, hosiery, etc.

Numerous packaging machines and methods can be found in the prior art. One such machine which can wrap the same type of article in similar wrapping materials as the present apparatus is described in US. Patent No. 3,158,973 issued to A. C. Monaghan on Dec. 1, 1964. In this prior art machine two rolls of film are held in spaced apart relation one above the other with the loose ends of the film from each roll sealed together intermediate the two rolls. An article to be packaged is pushed against the film in the vicinity of the seal; thereby striking the film and pulling off suflicient film from the rolls to wrap the package. The package is then sealed around its periphery by heat which simultaneously severs the film covering the package from the unused portions of the film. This sealing and severing method leaves the loose ends of the film from the two rolls sealed together so that another package may be wrapped in like manner. However, a package striking the film in the vicinity of the still warm seal quite often tears and damages the seal so that a satisfactory, completely sealed package does not result. Therefore, it is an object of the present invention to provide a method and apparatus which will package articles with highly reliable seals.

It is another object of the invention to provide a faster and more efiicient wrapping method by making it unnecessary to wait for the warm seals to cool and become completely fused.

These and other objects and advantages are accomplished by the present method and apparatus in which a stream of air is employed to simultaneously advance the sealed portion of the film ahead of the package while the package itself is being advanced. The stream of air also cools and thereby strengthens the seal. The package never directly pushes against the film and the integrity of the seal is preserved long enough for it to become adequately fused. The operation of the method and apparatus may be better understood by reference to the attached drawings in which:

FIGURE 1 is a schematic representation of a side elevation in section of an apparatus embodying the present invention;

FIGURE 2 is a schematic representation of the view seen along section line 22 of FIGURE 1;

FIGURE 3 is a front view in elevation of the apparatus in FIGURE 1;

FIGURE 4 is a rear view in elevation of the apparatus in FIGURE 1;

FIGURE 5 is a section taken along lines 5-5 of FIG- URE 2 showing the air nozzle and seal bars in detail; and

FIGURE 6 is a schematic representation of the steps in the method of the present invention.

The method of the present invention will be first described and then a preferred apparatus for carrying out the method will be described. The method can be more easily understood by first referring to FIGURE 1 which is a schematic representation as some of the parts are placed in the position shown merely for the ease of illustration. In FIGURE 1, two spaced apart rolls of heat sealable film 23 and 25 can be seen. The continuous sheets of film being drawn from these rolls are designated 43 and 44 and they are joined intermediate the two rolls at seal 45. A package P" is shown on platform 11 in position to be advanced toward the film seal 45 by pusher 9. Pusher 9 is actuated by air cylinder 10. A stream of air is directed against the film being fed by driven

pinch rollers

24 and 26 in direct ratio to the forward motion of the package. The next step in the packaging and sealing sequence can best be understood by referring to FIGURE 6.

In FIGURE 6, five sequential steps are shown which are labeled a, b, c and d. FIGURE 6a shows package P" in the same position as in FIGURE 1. Air is now being blown from nozzle 12 and is indicated by the arrow coming therefrom. In FIGURE 6b, pusher 9 has engaged the package and has pushed it forward toward the film seal 45 as simultaneously additional lengths of

film

43 and 44 are fed from the roll so that the force of air can cause the sealed together film to bellow out in front of the package. In FIGURE 60, the pusher 9 is nearing the end of its stroke as additional film is being fed so that the air stream can keep the seal advanced ahead of the package. Also seen in FIGURE 6c are

seal bars

16 and 17 and exit conveyor 18. The seal bars as shown are merely illustrative since the portions of the bars which would seal the sides of the package have been deleted. Also, both seal bars can be made to move, or the bottom one can remain stationary and the top one move. It is understood that the package P" is, for the purpose of this illustration, rectangular in shape and the package is advancing with its front side forward and the pusher 9 engages the back of the package.

In FIGURE 6d, the pusher 9 has withdrawn and the

guide rolls

14 and 15 have brought the two pieces of

film

43 and 44 together.

Seal bars

16 and 17 have closed and heat is applied through seal bar 17 so that the film is severed and sealed. Films which are particularly suitable for this operation are biaxially oriented, cross-linked thermoplastic film such as can be made from polyethylene or polypropylene. After the package has been scaled on its two sides and sealed and severed on its back side it is carried away by exit conveyor 18. The sealing and severing operation leaves a seal between

film sheets

43 and 44 so that the sequence may be repeated for the next package. It should be noted that in none of the steps just described did the package bear directly against the film in the sealed area. The film was fed simultaneously in direct ratio to the packages advancement; and, the force of the air stream kept the film seal in front of the package while also cooling the seal. Thus, the package does not at any time forcibly strike the film to pull film from the alls and the problem of a torn or defective seal is elimiated.

The package as wrapped in FIGURE 6d is ready for se. However, if maximum attractiveness and protection desired then a heat shrinkable film such as one menioned above will usually be used so that the package fter leaving exit conveyor 18 will continue on to a heat- 1g tunnel where hot air is blown against the package ausing the film to shrink tightly thereagainst. If the packge is to be heat shrunk then prior to the final sealing peration a small hole will be punched in either film sheet -3 or 44. This will allow air to escape as the film is shrunk Lown around the package.

The steps of the above described method are employed [1 a preferred apparatus which can best be understood by eferring to FIGURES 1 and 2. As stated above, the rrangement of the parts in FIGURE 1 is approximate .nd not actual as these parts are shown in this manner or ease of description. Likewise, FIGURE 2 is shown vith some parts omitted so that the function of the aparatus may be more easily appreciated. All the parts of he apparatus are carried by metal frame 1 which is hown in both FIGURES 1 and 2. This frame provides he main means of support and also carries control panel 16.

Infeed conveyor 2 delivers packages into position to be vrapped. The packages may be delivered to infeed coneyor 2 by another belt or a roller track. Infeed conveyor 5 is preferably intermittently operated or it can be coninuously operated. The belt for infeed conveyor 2 is 'oraminous in construction so as to permit a vacuum to be lrawn therethrough. Vacuum drawn through port 51 acts hold packages more securely against belt 2 so that in he quick starts in intermittent belt operation the belt will tot slip beneath the package. A package being conveyed )n infeed conveyor 2 will first pass across vacuum sensor iand then strike stop switch 3. The belt continues to opertte; and when a second package crosses vacuum sensor i, pneumatic cylinder 6 is actuated so that first pusher will push the package from position P, as shown in FIG- JRE 1, across upper platform 8 to position P. The sur- Face of platform 8 is smooth to permit easy travel of the Jackages thereon and guide members 7 keep the packages )roperly aligned. The body of nozzle 12 also acts at a guide 7. After a package has been moved to position P, a recond package pushed by the first pusher 5 will push the Jackage onto second platform 11 into position P". Plat- .orm 11 is smooth so as to permit easy sliding of packages- :hereon. Second pusher 9 can be seen in the space between irst platform 8 and second platform 11. The second )usher is actuated by pneumatic cylinder 10. While only me pneumatic cylinder is shown in FIGURE 1, a series )f four is preferably employed and these supply the main iriving force for the apparatus. In addition to moving sec- )nd pusher 9 the pneumatic cylinder 10 also drives chain 27. The movement of chain 27 is controlled by limit ;witch 38 so that when the chain is moved a predeternined distance an electrical signal is sent to an air valve which reverses the motion of pneumatic cylinder 10. Thus :hain 27 operates reciprocally. Sprocket 28 which is driven by chain 27 also drives chain 29 which in turn is :onnected to the sprocket on rear main drive shaft 30. Chain 29 and hence drive shaft 30 also operate recipro- :ally with the motion of cylinder 10. Chain 31 is driven by the sprocket on rear main drive shaft 30 and in turn drives the sprocket on clutch 32. Chain 31 also moves reciprocally under the influence of cylinder 10; but, because of the clutch 32, chain 36 moves intermittently in only one direction. Chain 36 supplies the motive power for axle 37 which operates exit conveyor 18. Thus, exit conveyor 18 also operates intermittently.

Clutch 32 also supplies one-way intermittent motion to chain 33, which drives the second clutch 34. Second clutch 34 drives chain 35 which in turn operates film 4 feed pinch rolls 24 and 26. Clutches 32 and 34 are engaged as second pusher 9 moves forward. Thus, the sheets of

film

43 and 44 are supplied as package P" moves towards seal 45.

Near the package at position P" air nozzle 12 can be seen supplied by air hose 13. As pusher 9 comes forward and advances the package toward the film seal 45 air is blown against the film. Simultaneously, through the chain drive described above, film is fed from rolls 23 and 25 and the exit conveyor 18 is set in motion. The exit conveyor belt is also made of foraminous material and a vacuum is drawn through the belt by vacuum ports 39 which are shown in FIGURE 2. The vacuum aids in advancing the film seal 45 in front of the package.

After the second pusher 9 has completed its stroke and has pushed the package into position P' it retracts; the motion of exit conveyor 18 stops; and, no more film is fed from rolls 23 and 25. Pneumatic cylinder 20 is then actuated driving upper seal bar downward along with roller 15, and cylinder 10 resumes its retracting cycle. When intermittent motion of the infeed conveyor is desired such motion can be achieved through a clutch driven by cylinder 10 as it retracts. The sealing bars 16 and 17 are in the shape of a large E. This configuration can be appreciated by viewing lower seal bar 16 in FIGURE 2. The arrangement permits the sealing of two packages simultaneously using only a single sheet of film 43 to cover the top of the package and a single sheet of film 44 to cover the bottom of the package.

The detail of the sealing bars 16 and 17 is shown in FIGURE 5 which is a section taken along line 55 of FIGURE 2. A resilient surface 42 is provided on lower seal bar 16 so that when the seal bars are closed heating wire 41 can press firmly against the film. While the bars are closed a timed electrical impulse is sent to heating wire 41 which is resistance heated, thus providing the heat to seal and sever the film. Also in FIGURE 5 a cross section of nozzle 12 is shown. After the sealing and severing operation, pneumatic cylinder 20 withdraws seal bar 17 and pusher 9 moves forward thus setting conveyor 18 in motion to carry the just sealed package to inclined roller track 19 where the package can be delivered either to another conveyor belt or to a roller track to carry it to a heat tunnel if heat shrinking is desired.

When the film on sealed packages is to be heat shrunk it is necessary to provide an opening in the film so that air may escape as the film shrinks tightly around the article. Deflate hole punch assembly 22, shown in FIG- URE 1, provides such a hole. The punch is heated above the melting point of the film 43 and the cooperating member of the assembly having a recess therein for receiving the tip of the punch drives the film against the punch in each wrapping cycle. The operation of the punch is more fully described in my copending application entitled Deflation Hole Punch and Method.

Immediately below the deflation hole punch 22 are guide rollers 21 through which film 43 passes. These rollers are driven by an air motor that co-acts with the film feed drive chain 35 and clutch 34 to keep the film taut.

The excess film which is trimmed off by the sealing and severing operation on the sides of the package is drawn off by vacuum nozzles 40 which can be seen placed on both sides of exit conveyor 18 immediately behind the outermost prongs of lower seal bar 16. A separate vacuum system is used for removing the trim scrap which is not shown in the drawings.

FIGURE 3 is a front view of the preferred apparatus showing the end view of the four pneumatic cylinders 10 which supply the main driving force for the apparatus. It is understood that some other driving means such as electrical motors could easily be substituted for these pneumatic cylinders. The end view of the sprocket on chain 27 can also be seen in FIGURE 3 and this chain drives the front drive shaft 28 which is located behind the sprocket. The locations of lower and upper film rolls 23 and 25 are shown along with an end view of first pusher and its actuating cylinder 6. Infeed conveyor vacuum lines 50 are also shown.

FIGURE 4 shows the rear view of the preferred apparatus with the control panel 46 located at the top. The exit conveyor 18 and the inclined roller track 19' are shown, and the vacuum lines 48 for the exit conveyor vacuum can be seen. Motor 47 supplies the vacuum for these lines 48. Vacuum motor 49 supplies the vacuum under the foraminous infeed conveyor belt 2. Rear main drive shaft 30 is located just behind these vacuum motors. Clutch 32, which imparts one-way intermittent motion to both the film feed and the exit conveyor, is also shown. Upper seal bar 17 and seal bar guides 52 are also shown in FIGURE 4.

For a more detailed description of the operational sequences of the preferred apparatus reference will be made again principally to FIGURES 1 and 2. As stated before, the infeed conveyor 2 will carry a package P over air sensor 4 and then to electrical stop switch 3. When the second package passes over air sensor 4 the vacuum which is being drawn through the air sensor is closed off thus signaling switch 3 to actuate the. air valve which starts air cylinder 6 in motion to drive first pusher 5. When first pusher nears the end of its stroke a limit switch is tripped which actuates air cylinder and sets second pusher 9 in motion and also moves drive chain 27. At the same time, the clutch 34 on the film feed drive chain 35 is engaged so that film will be fed. As the second pusher 9 moves forward film is fed and air is simultaneously blown against the film seal 45. Vacuum 39 behind the film is constant. Forward motion of second pusher 9 operates the exit conveyor belt 18. The forward motion of the second pusher 9 is stopped by limit switch 38 and as the pusher 9 returns the infeed conveyor belt is driven for the next cycle, and pneumatic cylinder 20 is actuated to close seal bar 17. A safety limit switch is provided on upper seal bar 17 to determine that pusher 9 is clear of the seal area. In the preferred arrangement shown in FIGURE 3 all four pneumatic cylinders 10 push the second pusher forward while two are used to draw the pusher 9 back clear of the seal bar 17. When the seal bar 17 closes on lower seal bar 16 the dwell time is electrically timed and a timed electrical impulse goes to resistance wire 41 to seal and sever the the film. As stated previously, lower seal bar 16 can be made movable, if desired. When the seal jaws reopen at the end of the timed dwell, the first pusher 9 is again triggered if the switch 3 and sensor 4 have been energized to move two more packages at position P. As previously stated, the exit conveyor moves as the second pusher 9 moves forward thus taking a package that would be at position P' out of the seal bar area and making way for the package which is then at position P". Second pusher 9 begins its stroke when the first pusher 5 completes its stroke. Thus, second pusher 9 will be in a retracted position under upper platform 8 when the package falls into position P" on second platform 11.

Not shown in FIGURE 1 is the drive mechanism for the infeed conveyor 2. This drive is a chain and clutch arrangement as used in the other above described drives. For the infeed conveyor 2 the clutch is engaged during the return stroke of second pusher 9 so that additional packages will be delivered to position P for the next wrapping cycle.

The drawings and descriptionherein are necessarily brief for the purposes of clarity. The essential mechanisms and their sequence of operation have been described so that one skilled in the art could readily construct the apparatus of the invention without requiring more detail.

The method and apparatus described herein can be used with any heat sealable material and is not limited to a heat shrinkable material. In fact, paper could be used in place of

film

43 and 44 and a pressure type adhesive could be applied by

bars

16 and 17 in conjunction with a pop-up knife edge to cut the paper. Also, the seal bars can be altered to accommodate packages of varying shape and sizes. The apparatus can be made to operate with either a single package feed or a double package feed. The apparatus can easily be changed to a single feed by eliminating the center prong in the seal bars, removing the center package guide 2, and placing nozzle 12 below the surface of second platform 11. Similarly, a triple or quadruple feed could be made by adding additional prongs to the seal bars and by adding the appropriate exit conveyors and air nozzles.

The rolls of film do not necessarily have to be placed one above the other but could be side by side. In other words, the apparatus could be altered to operate in an arrangement that would resemble the present configuration on its side. In addition, the rolls of film could be replaced by other sources of film such as a magazine of folded film.

In addition to the heat sealable and heat shrinkable packaging film mentioned above, films from polyvinyl chloride, rubber hydrochloride, polyvinylidene chloride and many others can be employed in this invention. Filmlike materials generally would be suitable.

Furthermore, the film seal 45 does not have to be advanced in front of the package by air blown from the same side of the film as is the package. A vacuum could be used to draw the film 45 in front of the package. Also, any suitable gas may be blown against the film and it may be either heated or cooled as desired.

Numerous modifications and alternations are possible within the scope of the foregoing described invention. It is understood that this invention is limited only by the following claims in which I claim:

1. A method of packaging articles in film-like material comprising the steps of:

(a) providing two sources in spaced apart relation from which said film-like material may be fed, the material from each source being sealed together intermediate the sources;

(b) simiultaneously,

(1) rrlioving an article to be packaged toward said sea (2) directing a stream of gas against the area of said seal to cool the seal and advance the sealed area ahead of said article whereby said article does not contact said sealed area until the seal has set; and

(3) feeding said film-like material from said sources as said sealed area is advanced; and sub-i sequently (c) sealing the film-like materials together around the unsealed portion of the periphery of the article when sufiicient film-like material has been fed from said sources.

2. The method of claim 1 wherein step (b) (2) is accomplished while drawing a vacuum on the side of the film opposite from the side from which said article is moving to aid in advancing said film-like material.

3. The method of claim 1 wherein the film-like material is a heat shrinkable and heat sealable thermoplastic material and the sealing of the film is accomplished by heat sealing.

4. The method of claim 3 wherein the sources of filmlike material which are provided in spaced apart relation are rolls of said material.

5. The method of claim 4 including the step of providing a deflate hole in the thermoplastic film.

6. Apparatus for packaging articles in heat sealable film comprising:

(a) means for holding two rolls of said film in spaced apart relation so that the loose ends of film from each roll may be sealed together intermediate the two rolls;

(b) means for advancing an article to be packaged towards said film seal;

(c)means for directing a stream of gas against said film seal to cool said seal and advance said film ahead of said article whereby the article does not contact said seal before it is set;

(d) means for feeding film from each roll simultaneously as an article is advanced towards the film seal;

(e) means for sealing together the film from the two said rolls around the unsealed portion of the perimeter of said article thus forming a wrapped package; and,

(f) means for conveying said package away from the sealing area.

7. The apparatus of claim 6 wherein the means for ad- 'ancing an article comprises:

(a) an infeed conveyor for articles to be wrapped;

(b) upper and lower platforms for receiving said articles;

(c) a first pusher for pushing articles off said infeed conveyor at right angles to the direction of motion of the conveyor onto said upper platform and pushing previously delivered articles off said upper platform onto said lower platform; and,

(d) a second pusher located in the space between said upper and lower platforms to push articles directly toward the film seal.

8. The apparatus of claim 7 wherein the means for lirecting air against the film seal area includes vacuum neans located on the other side of said film for drawing he film in the direction of travel of said article.

9. Apparatus for packaging articles in heat 'sealable,

ieat shrinkable thermoplastic film comprising:

(a) an upright frame having disposed at approximately midway its height upper and lower platforms for receiving articles;

(b) an infeed conveyor having a foraminous belt, said conveyor being in the same plane as said upper platform;

(c) a pneumatically operated first pusher adapted for pushing articles from said infeed conveyor at right angles to the direction of motion of said conveyor onto the upper platform;

(d) an exit conveyor having a foraminous belt positioned in spaced relation to said lower platform;

(e) a second pusher adapted for moving an article from said lower platform to said exit conveyor;

(f) mounting means for mounting one roll of film above said platform and another roll of film below 8 said platform whereby the loose ends of film from each roll may be sealed together, said seal being located at approximately the same height as said upper platform;

(g) means for directing a stream of air against said film seal in the direction of movement of said articles;

(h) vacuum means located below said exit conveyor belt for drawing said film in the direction of movement of said articles;

(i) driving mean-s for said second pusher, exit conveyor, and film comprising:

(1) at least one pneumatically operated cylinder adapted for powered reciprocating motion;

(2) a first drive chain driven reciprocally by said pneumatic cylinder, said first drive chain having associated therewith a limit switch for limiting the motion of said pneumatic cylinder;

(3) a second drive chain means;

(4) a first clutch driven by said second drive chain means, said first clutch having associated therewith drive chain means for imparting intermittent one-way motion to said exit conveyor; and

(5) a second clutch having associated therewith third drive chain means for imparting intermittent one-way motion to film from said rolls;

(j) seal bars having film guide rollers associated therewith, said seal bars being adapted to seal film covering the lowerportion of an article to film covering the upper portion of said article around the unsealed perimeter of said article;

(k) a pneumatic cylinder means for moving said seal bars in reciprocating vertical motion;

(1) heated punch means for punching a deflate hole in the film wrapped about each of said articles; and (m) an inclined roller track for receiving articles discharged from said exit conveyor.

References Cited UNITED STATES PATENTS 2,747,346 5/1956 Tigerman et al 53-28 3,355,857 12/1967 Tobey 53-182 THERON E. CONDON, Primary Examiner E. F. DESMOND, Assistant Examiner US. Cl. X.R.