US 3748825 A
In apparatus for completing the wrapping of articles in heat-sealable stretchable film, straightening rolls pull the laterally-extending portions of the tubular wrap film laterally and forwardly to remove all wrinkles and gatherings from the film just before the laterally extending portions are gripped by gripper means and pulled diagonally downwardly in a substantially vertical plane to stretch the film tightly about the article.
Description (OCR text may contain errors)
States Patent [1 1 [111 3,748,825
Chant, Jr. July 31, 1973 [5 FILM STRAIGHTENER APPARATUS FOR 3,537,235 11/1970 Pepmeier et al 53/373 WRAPPING ARTICLES IN STRETCHABLE 3,621,632 11/1971 Browning 53/138 A FILM Inventor: Albert H. Chant, Jr., Holland, Pa.
Assignee: J. B. Dove lnc., Levittown, Pa.
Filed: Apr. 22, 1971 Appl. No.: 136,358
Related U.S. Application Data Continuation-in-part of Ser. No, 823,736, May 12, 1969, Pat. No. 3,629,993.
U.S. Cl. 53/379, 53/206 Int. Cl..... B65b 7/08, B65b 51/10, B65b 65/00 Field of Search 53/203, 206, 209,
References Cited UNITED STATES PATENT-S 1/1965 lrwin et al 53/14 Primary ExaminerRobert C. Riordon Assistant Examiner-Neil Abrams Attorney-Paul & Paul  ABSTRACT In apparatus for completing the wrapping of articles in heat-scalable stretchable film, straightening rolls pull the laterally-extending portions of the tubular wrap film laterally and forwardly to remove all wrinkles and gatherings from the film just before the laterally extending portions are gripped by gripper means and pulled diagonally downwardly in a substantially vertical plane to stretch the film tightly about the article.
6 Claims, 5 Drawing Figures PATENIEU JUL3 I sum 1 or 3 INVEN'IOR.
Albert H. Chant, Jr.
PAIENIEU uw 1 I975 SHEU 2 [IF 3 INVENTOR Albert H.Ch0nr, Jr.
3 O 4 I 5 4 H ATTORNEYS PAIENIED JUL 3 SHEH 3 BF 3 mfw z ATTORNEYS.
FILM STRAIGHTENER APPARATUS FOR WRAPPING ARTICLES IN STRETCIIABLE FILM CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of my copending earlier-filed patent application Ser. No. 823,736, filed May 12, 1969, entitled Apparatus for Wrapping Articles in Stretchable Film, now US. Pat. No. 3,629,993, issued December 28, 1971. In the pres ent application, component parts which are common to both the present application and my earlier application are identified by the same reference numerals.
FIELD OF THE INVENTION This invention relates to apparatus for wrapping articles in stretchable heat-sealable film. One example of the sort of article which may be wrapped by the apparatus of the present invention is the well-known tray of meat or poultry as displayed for sale in the refrigerated display counter of a super-market.
BACKGROUND OF THE INVENTION In my earlier patent application, Ser. No. 823,736, now US. Pat. No. 3,629,993, apparatus is disclosed for wrapping articles in stretchable heat-sealable film wherein gripper chains on each side of the conveyor grip the top and bottom portions of the film which extends laterally from opposite sides of the partially wrapped article and pulls the film downwardly and forwardly in substantially verticle planes. The film is pulled, to each side of the article, over a film-guiding ledge which is higher than the undersurface or bottom of the article, thereby causing the film which projects laterally from the bottom of the article to pass upwardly along the sides of the article and over the sides of the film-guiding ledge before entering into the gripper chains. By such means, the pull on the film is distributed betwben the film covering the top and the film covering the bottom of the article, with consequent stretching of the film across both the top and underside of the article.
SUMMARY OF THE INVENTION The object of the present invention is to provide means, in apparatus of the general type referred to above, for assuring that the film is fully stretched by the gripper means, and not merely straightened or partially stretched.
Stated another way, the object of the present invention is to provide means for taking out all wrinkles and gatherings which the partially wrapped film would otherwise have at the time it enters the gripper means. If such straightening means is not provided, the gripper means in pulling the film diagonally downwardly will be unable to stretch the wrinkled film about the package to the full extent desired.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan view of a fragment of the wrapping apparatus showing the straightening device of the present invention;
FIG. 2 is an elevational view looking along the lines 2-2 of FIG. 1 toward one side of the apparatus from the center axis the machine;
FIG. 3 is an elevational front view of one side of the machine looking along the lines 3-3 of FIG. 2;
FIG. 4 is an elevational view, enlarged, looking along the lines 44 of FIG. 3, showing the straightening device of the present invention;
FIG. 5 is a diagrammatic illustration showing how the straightening device operates to straighten out the film just before it enters into the grip of the gripper chains.
DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, the articles move from right to left in the direction indicated by the arrow. The partiallywrapped articles, identified as A in FIG. 3, are placed successively, either by manual or mechanical means, on the support rollers 10, at the input end of the machine, the right-hand end as viewed in FIG. 1. At the time the article is so placed, it is partially enclosed in a tube of heat-scalable stretchable plastic film F. One film type would be stretchable plastic film of polyvinylchloride copolymers, otherwise known as PVC. As is well known, these are tough, non-toxic films characterized by the tendency to want to stick or cling to itself.
The tubular piece of PVC or other stretchable plastic film F, in which the article A is partially enclosed at the time it is deposited on the rollers 10 at the input end of the machine, extends or projects laterally in both directions beyond each side of the article, and these projecting protions, which for convenience are identified in the drawing by the letters PF, are supported on side ledges 12. It should be pointed out that the apparatus is symmetrical about its longitudinal center axis, each side having similar and corresponding parts. Accordingly, it will be necessary to describe but one side of the machine.
As seen in FIG. 3, the rollers 10 are supported in generally U-shaped brackets 41, with the outer leg 41B of the bracket being higher than the inner leg. The increased height of the outer leg 41B serves an important and useful purpose in that it functions as a package guide and also provides a support which maintains the level of the laterally projecting film portion PF above the bottom of the article A. As a result, the film F about the bottom of the partially-wrapped article A is raised by the bracket leg 418 up along the side of the article A, as indicated by the dot-and-dash lines in FIG. 3. During the initial portion of the transport through the machine, the laterally projecting portions of film PF rest on the ledge 12.
The articles A are transported forwardly, toward the left as viewed in FIGS. 1 and 2, by carrier arms 76 which are carried at spaced intervals on the powerdriven carrier chain 74. Two of the arms 76, one on each side of the apparatus, push against the article A and transport it forwardly toward the stretch station at which are located gripper chains I8 and 20. Such gripper chains are mounted at each side of the path along which the articles are being transported.
The gripper chains 18 and 20 grab the ends of the laterally projecting portions PF of the film F and pull it progressively downwardly in a diagonally forward direction in a plane which is normal, or substantially normal to the path of movement of the article A through the machine. The film ends are not pulled laterally by the gripper chains, either in the outward or inward direction. The pull is only vertically downwardly along a diagonally forward path. The film F on the top of the article and also at the underside of the article is subject to lateral pull in both directions, but this lateral pull is the result of a vertically downwardly pull on the film ends by the gripper chains.
The manner in which the projecting portions PF of the film on each side of the article A enter into the nip of, and are gripped by, the gripper chains 18 and 20 is fully discussed in my earlier filed copending application Ser. No. 823,736, now U.S. Pat. No. 3,629,993, and need not be described in detail in the present application.
While either or both of the gripper chains 18 and 20 may be power driven, in the particular machine illustrated and described in my aforesaid US. Pat. No. 3,629,993, only the lower gripper chain 26 is power driven, with the upper chain being in close intimate interleaved engagement with and driven by the driven lower chain. The same arrangement is illustrated in the present application.
Shown in FIG. 3 is a representation of a drive motor 42 and one of the side frames 50 of the machine. Motor 42 drives an output shaft 41 on which is mounted a sprocket 43 about which is trained a drive chain 44. Chain 44 is trained over and drives a sprocket 52 which is mounted on and fixed to a shaft 51 supported for rotation in the side frame 50.
Also mounted on and keyed to shaft 51 is a sprocket 55 about which the lower gripper chain 20 is trained. Also supported on shaft 51, as by a keyed bearing member 167, is a laterally-movable intermediate frame 67. A bracket is mounted on frame 167 which supports a track or guide 82 (see FIG. 2) about which the lower gripper chain 20 is trained.
Also mounted on and keyed to shaft 51 is a sprocket 73. Sprocket 73 drives a carrier chain 74 which carries a plurality of pusher arms 76 at spaced-apart locations. The carrier chain 74 is trained about a rail 77, best seen in FiG. 2. Rail 77 extends the full length of the machine.
For the purpose of enabling the apparatus to wrap articles of different width, provision is made for adjusting the effective width of the machine. For this purpose, shaft 51 is provided with a keyway 151 for a substantial portion of its length, and the bearing member 167 and both of the sprockets 55 and 73 are keyed into the elongated keyway 151 and are adapted to be moved axially along the shaft 51. Movement along the shaft 51 is accomplished by two adjusting rods, one of which, rod 65, is shown in FIG. 3. The other rod does not appear in the drawings of the present application, but the width adjusting means now being referred to are fully described in my copending application, Ser. No. 823,736. It will be sufficient for the purpose of the present application to say that a width-adjusting motor drives a rod which drives a chain which drives a sprocket 64 shown in FIG. 3 and keyed to shaft 65. Adjusting rod 65 is externally threaded and carries an internally threaded bearing member 66 to which the intermediate frame 67 is secured, as by bolts. The lower end of the intermediate frame 67 is supported on the drive shaft 51 by the keyed bearing member 167. As seen in FIG. 3, bearing member 167 is held by a clip 168 against a shoulder of a sleeve 71. Sleeve 71 is connected to, or integral with, the hub of sprocket S and the hub of sprocket 73.
It will be seen that when the adjusting rod 65 is driven, the internally threaded bearing member 66 moves axially along the shaft, thereby moving the intermediate frame 67 either inward or outward according to the direction of rotation of the adjusting motor and adjusting rods. When the intermediate frame 67 is moved, the bearing member 167 on shaft 51 is moved axially along shaft 51 and so are sprockets 55 and 73 together with the track of the lower gripper chain 20, and the track of the upper gripper chain 18. Also moved is rail 77 of the carrier chain 74, since rail 77 is connected to the intermediate frame 67 by a support member 78, a fragment of which is shown in FIG. 3.
As already indicated hereinabove, in the embodiment illustrated in my earlier-filed application, and also in the present application, only the lower gripper chain 20 is power driven. The upper chain 18 is locked with and is driven by the lower chain. In some cases it may be desirable to drive the upper instead of the lower gripper chain, and in other cases it may be desirable to drive both. In any event, the gripper chains are, of course, driven at a speed which is related to the speed at which the articles are being pushed through the machine by the carrier arms 76. This is most readily achieved by driving both the carrier chain 74 and the gripper chains from a common drive shaft, namely, shaft 51. It is important that the horizontal component of the gripper chain speed be equal to, or be somewhat greater than, the speed of the pusher or carrier arms 76, as otherwise package damage may result.
With respect now to the straightening device which is added as an improvement to the apparatus described in my earlier-filed application. It has been previously indicated hereinabove that one type of heat-scalable stretchable plastic film which is popularly employed for package wrapping is PVC, a polyvinylchloride polymer, since this type of film is tough and non-toxic. However, PVC has a tendency to cling to itself.
If the tubular wrapped film, in which the article A is partially wrapped at the time it is deposited on the rollers 10, is wrinkled or gathered upon itself, then the gripper chains in pulling downwardly on the film may merely straighten out the film without any stretching, or may straighten out the film with some degree of stretching but less than full stretching. To assure that the film is fully stretched by the gripper chains, a straightening device is, in accordance with the present invention, incorporated into the wrapping machine described and claimed in my earlier filed copending application.
As seen in FIGS. 2 and 3, and as previously de scribed, the drive motor 40 drives shaft 51 through drive chain 44 and sprocket 52. In accordance with the present invention, sleeve 71 on shaft 51 is extended to the left, as viewed in FIG. 3, beyond bearing member 167, anda gear is mounted on the extension 171 of sleeve 71. Gear 110 meshes with and drives a gear 111 which is mounted on a stub shaft 168 supported in a plate 167 which is bolted to the intermediate frame 67. Mounted on and keyed to the stub shaft 168 is a sprocket 112 about which is trained a chain 113. The other end of chain 113 is trained about and drives a sprocket l 14 mounted on and keyed to a stub shaft 170 which is joumalled as by bearing 169 in the intermediate frame 67. Keyed to shaft 170 and rotatable therewith is a pulley 115 having trained thereabout a pulley belt 1 16, best seen in FIG. 5. As seen in FIG. 4, belt 1 16 is trained over a guide pulley 117, under guide pulley 1 18, about the work pulley 119, and over a guide pulley 120. The pulleys 117, 118, 119 and 1120 are mounted on a mounting plate which is secured, as by screws,
to the intermediate frame 67. The major portion 131 of mounting plate 130 lies in a plane parallel to that of the intermediate frame 67, but the lower corner portion 132 is angularly disposed relative to the plate of the intermediate frame 67. Guide pulleys 117 and 120 are mounted on the portion 131, but guide pulley 118 and work pulley 119 are mounted on the angularly disposed portion 132.
A slot is cut in ledge 12 just below work pulley 119 and a spring-biased roller 121 is mounted on the undersurface of ledge 12 to exert upward pressure against the belt 116 at pulley 119. The roller 121 is so angularly mounted that it rotates in the same angular plane as that of the pulleys 119 and 118. The gear ratio between gears 110 and 111 is so chosen that belt 116 is pulled about work roller 119 at a surface speed somewhat greater than that at which the carrier arms 76 are moving the package A forwardly. As a result, and due to the angular disposition of the roller 119 and its springbiased backup roller 121, the laterally-extending film PF is pulled both laterally and forwardly. This action occurs at both sides of the machine, and accordingly, any wrinkles or gatherings of the film are straightened out just before the film ends enter into the grip of the gripper chains 18 and 20. Thus, the gripper chains 18 and 20 are able to perform their intended purpose of fully stretching the film about the article.
Work pulley 119 and spring-biased pre-load wheel 121 may preferably be disposed at an angle of the order of 30 relative to the center axis of the machine or path of movement of the articles A. The angle is not critical and may vary to either side of 30 by some 5 to It is important, however, that the work pulley 119 and belt 116 exert both a forward and lateral pull on the film ends.
It is desirable that the belt 116 have a surface speed, at its point of contact with the film, equal to or greater than that of the gripper or stretch chains 18, 20. This speed, as previously indicated, should be faster than the speed at which the pushers 76 push the article A through the machine. The relationships as to speed are most readily achieved by using a common drive for the stretch chains, straightener, and article pushers. By such an arrangement, a forward pull may be provided on the article which relieves the pressure of the pushers and avoids possible damage to the package from excessive push force.
The belt 116 in the straightener device may be round or V-shaped in cross section. It is made of frictional material, preferably polyurethane.
in the illustrated machine, the work pulley 119 is located above the film, and the pre-load wheel 121 is below the film. These positions may, however, be reversed.
The straightener device has been illustrated in combination with a stretch wrapping machine in which the lower one of the stretch chains 18 and is power driven. The straightener device may, however, also be incorporated into a stretch wrap machine in which the upper one of the stretch chains is driven. Or, the straightener device may be used independently of the stretch mechanism.
What is claimed is:
1. Apparatus for wrapping articles in stretchable film, said apparatus including:
a. support means for supporting a series of articles partially wrapped in tubular manner with stretchable film the open ends of which project laterally in both directions beyond opposite sides of the articles;
b. carrier means for transporting said series of partially wrapped articles in succession along said sup port means;
0. a film-stretching station;
(1. film-straightening means immediately preceeding said film stretching station for pulling said laterally projecting portions of film diagonally forwardly and laterally relative to the advancing article to remove lateral drag and laterally straighten out said dragging portions just before said projecting portions are presented to said filmstretching station;
c. said film-straightening means comprising a moving surface in contact with said laterally projecting portions and having a surface speed at its point of contact with the film which is faster than the speed at which said articles are being transportedby said carrier means;
said film-stretching station including;
f-l. a pair of endless gripper chains disposed in vertical relation, one above the other, at each side of said support means;
f-2. track means for each of said gripper chains maintaining the upper reach of the lower chain in continuous interleaved interlocking pressure engagement with the lower reach of the upper chain;
f-3. means for driving said gripper chains at a speed relating to that of said carrier means and such that the horizontal vector component of the gripper-chain speed is greater than the transport speed of the carrier means;
f-4. said gripper chains operating to grip the ends of said projecting portions of said film and to pull the same diagonally downward below the advancing article and forward thereof in substantially vertical planes to progressively stretch said film over said article.
2. Apparatus according to claim 1 characterized in that: a. film guide means are provided supported at the sides of said carrier means and forming at each side a ledge at a level higher than the undersurface of the articles transported by said carrier means for causing laterally projecting portions of said bottom portion of said film to pass upwardly along the sides of the transported articles and over said ledges of said film guide means before entering into said gripper means to be pulled diagonally downwardly and forwardly thereby, whereby the pull on said stretchable filmis is distributed between the film covering the top and bottom of the article with consequent stretching of the film across both the top and underside of said articles.
3. Apparatus according to claim 1 wherein:
a. said moving surface of said film-straightening means is an endless belt trained about a series of pulleys at least one of which is so positioned that the portion of belt trained thereabout contacts said laterally projecting portions of said film;
b. said pulley, about which the film-contacting portion of said belt is trained, is disposed at such an angle relative to the center axis of said machine that the film-contacting portion of belt pulls the laterally projecting film substantially forwardly as well as laterally.
film-contacting belt is trained, is disposed at an angle of between 20 and 40 relative to the center axis of the wrapping apparatus.
6. Apparatus according to claim 3 characterized in that said angularly disposed pulley disposed at an angle of the order of 30 relative to the center axis of the wrapping apparatus.