GB2153328A - Wrapping apparatus - Google Patents

Abstract

In a packaging apparatus for wrapping filled trays (2), a flexible and stretchable film which has been tubed around successive trays, is cut by a cutting arrangement (69,71) between trays (2) so that a leading end (3b) of the cut tubular film is taken in a first air suction channel (64), held therein by a damper and then folded towards the bottom surface of tray 2 upon advancing movement of the latter and a trailing end (3a) of the film is taken in a second air suction channel (65) and held therein by a further damper (98) and then folded towards the bottom of a tray by a roller means (100) which has an opening 106 and moves in the advancing direction of the tray at a greater speed than the latter. <IMAGE>

Description

SPECIFICATION Packaging apparatus This invention relates to-.a packaging apparatus for packaging articles together with trays containing them in plastics film, and more particularly to a packaging apparatus in which a number of trays containing articles is disposed inside a tubular film and the tubular film cut between the respective trays and then extended and folded back against the bottom surface of each tray.

The packaging apparatus of the invention, as shown in Figs. 1 2 to 14, is concerned with packaging articles 1 contained in a tray 2 and enveloped in a tubular film 3, the film 3 at first extending longitudinally beyond each end of the tray 2 and then being folded back at both ends against the bottom surface of the tray 2. In this case, the film is previously expanded to be free from wrinkles, whereby the articles are made clearly presented through the transparent film.

A conventional packaging apparatus as previously proposed in the United States Patent No. 4,144,697 by the inventor of the present invention, comprises means tor making an elongate band of tubular film and means for feeding articles to the tubular-film-making means at regular intervals, means at the downstream side of the tubular-film-making means for cutting the film between the adjacent trays, suction means which uses an air flow to suck downwardly both ends of tubular film at both sides of tray, roller means having an opening in part for folding the upstream side end of tubular film towards the bottom surface of each tray, and means for folding the downstream side end of the tubular film towards the bottom surface of each tray.In more detail, the packing apparatus disclosed in the United States Patent No. 4,144,697 conveys the trays in the tubular film continuously on an air suction channel so that both ends of the tubular film are stretched downwardly by suction applied to both ends and caught by the predetermined hook element to be folded toward the bottom surface of each tray. Such method requires a longer air suction channel larger and hence in turn a relatively large apparatus. In order to solve this problem, a method is proposed which transports the trays intermittently to cuts the film during the intervening stops and then both ends of the cut film are taken in the lower air suction channel and folded downwardly simultaneously with resumption of transportation of the trays. With such a method it is possible to reduce the length of the air suction channel to hence the size of the apparatus.However the packing capacity and rate is limited. Also suction by air is insufficient to stretch the film ends. For example, sliced-meat products are mostly presented in trays and a thermoplastic film merely covers the upper opening of the tray 2 as shown in Fig.14. The film is moreover made as thin as possible for reasons of economy. This kind of film has increased friction as it is stretched so that both ends 3a and 3b of film folded against the bottom surface of tray stick readily thereto even without heating.Some films are extensible by as much as 300% and with the thinnest possible films insufficiently stretching thereof has the result that the film extending over the mouth of the tray can slacken even with minute temperature changes resulting in reduced transparency of the film, and possibly wrinkling resulting in an inferior presentation of the articles.

It is an object of the present invention to avoid or minimize one or more of the above disadvantages.

The present invention provides a packaging apparatus for wrapping trays containing articles in flexible and stretchable film, which apparatus comprises, a conveyor for transporting said trays, a supply means for supplying to said trays transported by said conveyor, in use of the apparatus, a band of said film at a speed equal to said conveyor so as to wrap each of said trays in a tubular-shaped length of said film, a cutting means for cutting said tubular film wrapping each of said trays be; tween successive trays in the transport direction thereof, and a folding means for folding downwardly the leading and trailing ends of respective film lengths cut by said cutting means and sealing said ends to the bottom surface of each of said trays, wherein is provided a first air suction channel for turning downwardly the leading end of said film length cut by said cutting means and a second air suction channel for turning downwardly the trailing end of said film length cut by said cutting means, said air suction channels being disposed between said successive trays in the transport direction thereof with respect to said cutting means, and provided with air inlets open upwardly respectively and with a first film holding means and a second film holding means which are provided within said air suction channels and hold therein the leading and trailing ends of said film lengths taken in through respective ones of said air inlets, a side-belt means which sandwiches laterally said trays covered by said tubular film and forcibly transports them so that said trays are allowed to pass through said cutting means and first and second air suction channeis to thereby fold downwardly towards the bottom surface of each of said trays the leading end of said film held by said first film holding means within said first air suction channel, and a roller means of endless-belt type which moves at a higher speed than said side-belt means thereby to fold downwardly towards the bottom surface of each of said trays the trailing end of said film held by said second film holding means within said second air suction channel, said roller means providing an opening registering with said air inlet of said second air suction channel.

Thus a packing apparatus of the invention comprises a first air suction channel for turning downwardly the leading end of the tubular film wrapping the articles and cut by the cutting mechanism, a second air suction channel for turning downwardly the trailing end of the same, the first and second air suction channels being disposed at the upstream and downstream sides of cutting mechanism and having air inlets 'respectively, first and second film holding means provided in the first and second air suction channels for holding both the ends of the film taken therein through the air inlets respectively, a side belt means for putting therebetween the trays wrapped by the film and positively transporting them across the first and second air suction channels and also folding the leading end of the tubular film towards the bottom surface of each tray, and a roller means of an endless belt system which moves faster than the side belt means so that the trailing end of the film held by the second holding means is folded towards the bottom surface of the tray and also has an opening registering with the air inlet of the second air suction channel.

In the packing apparatus of the invention, the air suction channels merely take therein the leading and trailing ends of the traywrapping film, and can thus be relatively small whilst the side belt means positively transports the trays and the roller means moves faster than the trays while holding both the ends of tubular film with the first and second holding means so that both ends are forcibly folded towards the bottom surface of each tray, the trays are transportable continuously and also the film is sufficiently tensioned. As a result the problem of wrinkling of the film covering the trays is substantially avoided.

Further preferred features and advantages of the invention will appear from the following detailed description of some preferred embodiments illustrated with reference to the accompanying drawings in which: Fig. 1 is a side view of a first embodiment of a packaging apparatus of the invention; Fig. 2 is a detail view on an enlarged scale of the tubular-film making means of the apparatus of Fig. 1; Fig. 3 is a reduced scale plan view of the tubularfilm making means of Fig. 2; Fig. 4 is a schematic plan view of the power transmission of the apparatus of Fig. 1; Fig. 5 is a detail plan view of part of the apparatus of Fig. 1 which includes a cutting means; Fig. 6 is a sectional elevation of the cutting means on the line VI-VI in Fig. 5; Fig. 7 is a partially sectioned side elevation of the cutting means and adjacent machinery;; Figs. 8 to 10 are views illustrating the mode of operation of the principal part of the apparatus shown in Fig. 7; Fig. 11 is a sectional elevation taken on the line 11 1 1 a in Figs. 3; and Figs. 1 2 to 1 4 are illustrations of packaged articles.

Fig.1 shows a packaging apparatus of the invention comprising a housing 10 and various mechanisms mounted thereon. A conveyor 1 2 for supplying the trays containing articles to be packaged is mounted on a frame 11 connected horizontally to the housing 10 at the left hand end thereof (as viewed in Fig.

1) and comprises an endless chain 1 3 having projections 1 4 mounted thereon at regular intervals, for engaging the trays to slide them along the frame 11.

The housing 10 supports at an upper portion thereof rollers 1 5 and 1 6 carrying a roll of film 3, and below the rollers 1 5 and 1 6 and at its upper surface a conveyor 1 7. The conveyor 1 7 is positioned to be in line with the tray feed conveyor 1 2 and comprises an endless belt 1 8 supported on the housing 10 by means of pulleys 19, 20 and 21 as shown in Fig. 2.

A film transport mechanism 22 arranged for transporting the film from above the conveyor 1 7 horizontally and downwardly, is disposed along both sides of conveyor 17, and comprises a pair of endless chains 23 supported on pairs of chain wheels 26, 27 and 28 on a pair of support plates 24 fixed to respective sides of the housing 10, the endless chains 23 providing a plurality of clips 30 spaced at uniform intervals from one another. The chains 23, as shown in Figs. 2 and 3, are spaced at the upstream side at a distance approximately equal to the width of the film 3, in an intermediate zone at a greater distance, and at the downstream side at a smaller distance, the series of chain wheels 26-28 converging towards each other. The clips 30, as shown in Fig. 2, each comprise a fixed segment 31 and a movable segment 32 which are mounted on the chain 23, each clip 30 being adapted to be closed by a spring 33 and opened by a cam 34 or 35.

A tubular-film making means 37 for stretching transversely the film and wrapping it around the trays 2 in a tubular form is provided in continuation of the conveyor 1 7. The tubular-film making means 37, as shown in Fig. 3, comprises a pair of throttle plates 38 and pairs of rollers 39 and 40 positioned thereunder, the throttle plates 38 being juxtaposed and opposed at their inner edges 41 in a generally V-shaped configuration and partly overlapping with the rear ends of the film conveyors 22 respectively.

A side belt means 43 extends from above the tubular-film making means 37 towards the downstream side thereof and comprises, as shown in Fig. 4, a first pair of opposed endless belts 44 at the upstream side and a second pair of opposed endless belts 45 at the downstream side on opposite sides of the tray path. Between the first and second pairs of side belts 44, 45 is provided a cutting means 63 further described hereinbelow. The four side belts 44 and 45, as shown in Fig. 1, are rotatably mounted via pulleys on frames 46 and 47 which are provided above said side belts 44 and 45 and fixed to the housing 10 by means of rods 48 extending transversely respectively.The frames 46 at the upstream side and those 47 at the downstream side are, as shown enlarged in Fig. 7, connected by a gate member 49, and gears 51 coaxial with pulleys 50 at the upstream side and gears 53 coaxial with pulleys 52 at the downstream side, are connected through idler gears 54 pivotally connected to the connecting member 49 respectively, thereby transn'itting a driving force to each belt 44 or 45 relative to each other.

Referring to Fig. 3, arms 56 project from the frames 46 of the side belt means 43 towards the inside of the film transport means 22 and provide film stretching belt means 57 respectively. The film stretching belt means 57, as shown in Figs. 2 and 11, comprise cables 61 supported rotatably on the arms 56 by the means of grooved pulleys 58, 59 and 60 respectively, the cables 61 functioning to urge the film downwardly at both sides of each tray 2 transported by the conveyor 1 7.

The film cutting mechanism 63, as shown in Fig. 1, is provided at an intermediate portion of the side belt means 43 and a first air suction channel 64 is provided at the upstream side of the cutting means 63 and a second air suction channel 65 at its downstream side, the air suction channels 64 and 65 forming upwardly directed air inlets, and connecting at their lower ends through a duct 66 with a vacuum pump 69 provided within the housing 10 so that air is always sucked into the channels 64 and 65 through said air inlets.

The film cutting means 63, as shown in Fig. 7, comprises a blade 69, a film-resistance giving plate 70, and an upper cutting element 71 grooved downwardly and provided above and opposite the blade 69, the blade 69, as shown in Figs. 5 and 6, being fixed to the first air suction channel 64 by means of screws 72 and having a saw-tooth-edge directed upwardly, the film-resistance giving plate 70 being sandwiched vertically movably between the blade 69 and the wall of first air suction channel 64. At both lengthwise ends of the blade 69 are provided vertical rod guides 73 of groove-shaped section and lifting levers 74 are inserted slidably into the grooves of guides 73 so that the upper cutting element 71 is fixed across the upper ends of lifting levers 74 by means of screws 75.

The guide rods 73 are mounted through seg ments 76 to frames 77 for a roller mechanism 100 at the downstream side respectively. Be low the segments 76, levers 79 are supported rotatably on the guide rods 73 through pins 78 respectively, pins 80 fixed to the inner ends of levers 79 engage with slits 81 respectively, and tension springs 82 are provided between the outer ends of levers 79 and the pole guides 73 so that the film-resistance giving plate 70 is biased by the springs 82 to project at the upper end upwardly from the edge of blade 69.Pulleys 83 are rotatably supported on the pins 80 at the levers 79 and cam plates 84 are fixed to the both side lifting levers 74 by screws 85 in such a manner that the opposite faces of cam plates 84 slope upwardly to reduce the distance there between, the levers 79 abutting against stop pers 86 thereby to.define the upper limit of upward movement of film-resistance giving plate 70.

Referring again to Fig. 7, an air inlet 87 is provided at the upper end of first air suction channel 64 and a roller 88 is provided at the edge of air inlet 87 at a side of the front wall of channel 64, the roller 88 rotating at the peripheral speed faster than the transportation speed of each tray 2 and functioning to positively guide in the air inlet 87 the leading end of the cut tubular film wrapping the tray 2. A first bypass port 89 is formed at the front wall of the first air suction channel 64, positioned below the roller 88, and directed towards the rear wall of the same. Also, a first damper 90 is provided within the first air suction channel 64, extends substantially lengthwise thereof, is pivotally mounted at the lower end on the side wall of the channel 64, and at its upper end is disposed opposite a mouth of the bypass port 89.The first swing able damper 90 has its centre of gravity disposed towards the front wall of channel 64, whereby the damper 90 normally leans over to close with its upper end the mouth of the bypass port 89 from inside the channel 64. On the other hand, the second air suction channel 65 at the downstream side of the cutting mechanism 63 comprises a bowl 94 having at its side wall a port 93 communicat ing with the vacuum pump 67 and a lid 95 mostly fixed to the upper end of bowl 94 and having in part an air inlet 96.A second bypass port 97 is open at the bottom of the bowl 94 and just below the air inlet 96, and a second damper 98 is provided at the second bypass port 97, rotatably supported at an intermediate portion on a horizontal pin 99, and adapted to be balanced to close the bypass port 97, in which the front end 98a of the second damper 98 is positioned below the edge of second bypass port 97 and the rear end 98b of the damper 98 above it. The mode of operation of the first and second dampers 90 and 98 is further illustrated in Figs. 8 through 10.

A roller means 100 comprising an endless belt 101 surrounds the second air suction channel 65 as shown in Fig. 7. The belt 101 is supported on rollers 102, 103, 104, and 105 so as to be rotatable around the second air suction channel 65; has an opening 106 at only one position so that when the air inlet 96 registers with the opening 106, the trailing end of the cut tubular film is sucked downwardly; and comprises a pair of endless chains 108 at opposite sides and a series of rod-like rollers 109 bridging across the chains 108 the rollers 109 extending substantially continuously except for the abovementioned opening 106.

Fig. 4 shows means for transmitting a driving force from an electric motor to the various operating means of the apparatus. The electric motor 111 has reduction gears and the supply conveyor 1 2 is connected thereto by means of a chain 11 2 so that the tray-feed conveyor 1 2 rotates continuously at constant speed, the motor 111 connecting with a chain 114 through an electromagnetic clutch means 11 3 which disengages for stopping each operating means as required, but normally is engaged to transmit driving force.The driving force is transmitted in part through the clutch means 11 3 to a rotary grooved cam 11 6 through chains 114 and 115 and a lever 117 engageable with the grooved cam 11 6 swings to move vertically the upper cutting element 71 of the cutting mechanism 63. The motor 111, grooved cam 11 6 and lever 117, are contained in the housing 10 as shown in Fig.

1, so that the lever 11 7 transmits its swinging motion to the upper cutting element 71 through the upper levers 11 8 and links 11 9.

The driving force for the cam 11 6 is also transmitted to the roller mechanism 100 through a chain 120, the driving force output from the electromagnetic clutch 11 3 is transmitted in part to a chain 1 22 through a variable speed gear 121, and the driving force from the chain 1 22 is transmitted to five shafts 123, 124, 125, 126 and 127, thereby rotating the film transport means 22, the belt conveyor 17, the rollers 39 and 40, the side belt means 43, and the roller 88. In addition, the variable speed gear 121 can change its output to adjust the speed of each mechanism as desired.On the other hand, the driving force transmitted from the clutch 11 3 through the chain 11 5 actuates the upper cutting element 71 of the cutting means 63 and the roller mechanism 100 at a relatively high speed in a speed-up gear ratio.

The mode of operation of the abovedescribed embodiment will now be explained.

Referring to Fig. 3, a number of clips 30 provided on the chains 23 is actuated by cams 34 rotating in the direction of the arrow at both turning points of the chains 23. When each clip 30 is actuated by each cam 34 as shown in Fig. 2, the movable segment 32 moves away from the fixed segment 31 against the spring 33 to open each clip 30 so that the film 3, when guided to the position where each clip 30 is temporarily open, is guided and then clipped by the clips 30 in sequence with each other as the chains 23 rotate, thereby being transported in the direction of the arrow and simultaneously stretched laterally.

The conveyor 12, as shown in Fig. 1, pushes the trays 2 with the attachments 1 4 and continuously feeds the trays 2 onto the conveyor 1 7 at the downstream side, the trays 2 being fed therewith under the film 3.

Since each chain 23 inclines downwardly and a chain wheei 28 at the downstream side is positioned lower than the upper surface of belt 1 8 at the conveyor 17,each tray 2 creeps below the film 3 so as to push up the film 3.

A pair of film stretching belts 57 are provided at both sides of the tray transport path so that the trays 2 travel between the belts 57 as shown in Fig. 11. The cables 61, which are supported rotatably by the plurality of pulleys 58, 59, rotate together with the moving film 3 and turn both side edges of film 3 downwardly at both sides of each tray 2. Since the film transport means 22 gradually approach each other and are intended to wrap each tray 2 with the film 3, the film 3 once stretched begins to slacken. The film stretching belts 57 however press the film 3 downwardly to prevent the slackness thereof.

As may be seen in Fig. 3, both the lateral edges of the film 3 are lower than each tray 2 and are forcibly brought in between the throttle plates 38 and stretched thereby. At this position, the film transport means 22 terminates so that the clips 30, as shown in Fig. 2, ride over the cam 35 at the rear turning point of each chain 23, thereby being automatically opened to release both side edges of film 3.

Both the side edges of film 3 released as abovementioned are sandwiched by the rollers 39 so as to be brought together and then deposited by rollers 40 at the downstream side. As a result, the film 3 becomes tubular around the trays 2 and contains them within at regular intervals, the trays 2 wrapped by the tubular film 3 entering between the side belts 43 and being transported therewith.

When the tubular film 3 is positioned at an intermediate portion between two trays 2 and just below the upper cutting element 71 as shown in Fig. 7, the element 71 lowers to cut the tubular film 3. As seenfrom Fig. 4, the upper cutting element 71 and conveyor 12 having the attachments 14 are operated by the same power system so as to operate in synchronism with each other, whereby the upper cutting element 71 lowers at the intermediate portion between two trays 2 in synchronism with the movement of the attachments 14 on the conveyor 12. Referring to Fig. 1, the grooved cam 11 6 continuously rotates to act on each lever 118, thereby vertically moving the upper cutting element 71 at the predetermined cycle period, as will be described below in more detail with reference to Fig. 6.Both the levers 11 8 are actuated to lower the lifting rods 74 along the guide rods 73, then the cam plates 84 urge the film-resistance-giving plate 70 downwardly through the pulleys 83, whereby the film-resistance-giving plate 70 lowers together with the upper cutting element 71 and is positioned below the level of the edge of the blade 69. Hence, the edge of blade 69 projects alone and the upper cutting element 71 lowers across the cutting edge of the blade 69, thereby cutting the tubular film 3 therebetween. As a result, leading ends 3b and trailing ends 3a of respective tubular film 3 lengths are formed between the adjacent trays 2 as shown in Fig. 8, the leading and trailing ends 3b and 3a being subjected to suction from the first and second air suction channels 64 and 65 respectively.When the leading end 3b of the cut tubular film length 3 is taken into the first air suction channel 64, the air inlet 87 thereof is closed by the leading end 3b thereby reducing suction of air into the first suction channel 64 as shown in Fig.

8. Consequently, a new air flow, as shown in Fig. 9, is created in the first bypass port 89 to push the first damper 90 toward the rear wall of channel 64 so that the damper 90 presses the leading end 3b of a film length 3 onto the rear wall. Next, in Fig. 6, when the upper cutting element 71 is pushed upwardly by both side levers 11 8 and the film-resistancegiving plate 70 is released, the springs 82 contract to raise the plate 70 above the ievel of the blade edge 69 as shown in Fig. 9.

When each tray 2, after cutting of the tubular film 3 passes above the film-resistanceaiving plate 70 under the driving force of side belt mechanism 43, the leading end 3b of film 3 is subjected to a frictional resistance from film-resistance-giving plate 70 and increases the frictional resistance by means of winding around the plate 70 because the leading end 3b is caught by the first damper 90, thereby being extended longitudinally and folded towards the bottom surface of each tray 2.

Then, the air inlet 87 is opened after the tray 2 passes above the first air suction channel 64 and the first damper 90 swings back to its original position under the influe of its centre of gravity disposition relative to the bypass port 89. On the other hand, the trailing end 3a of the tubular film length 3 is picked up by the second air suction channel 65 simultaneously with being cut as shown in Fig. 9. In other words, when the air inlet 96, as shown in Fig. 8, registers with the opening 106 of the continuously rotating roller means 100, the upper cutting element 71 lowers to cut the film 3 at a predetermined timing, whereby the trailing end 3a of the tubular film length 3 is picked up by the second air suction channel 65 through the air inlet 96 in register with the opening 106.Immediately thereafter, when the air inlet 96 is closed by the continuously rotating roller mechanism 100, air is taken from;the second bypass port 97 and flows to swing the second damper 9X, whereby the trailing end 3a of the film 3 is held by the end 98b of the second damper 98 onto the inner surface of the upper wall of the second air suction channel 65. The trailing end 3a is folded in a manner of winding around the edge of air inlet 96, and increases the frictional resistance, whereby the power of the roller means 100 rotating at higher speed than transport of the tray 2 stretches the film 3 longitudinally thereby folding the trailing end 3a of the tubular film length 3 towards the bottom surface of each tray 2.Incidentally, since the air inlet 96 is open through the opening 106 of the roller means 190 and air is taken in from the inlet 96, the second damper 98 returns to its original position.

Next, the trays 2, as shown in Fig. 1, are conveyed from the side belt mechanism 43 to a discharge belt conveyor 1 32. A heater plate 1 33 is positioned under the belt of conveyor 1 32 thereby to deposit both the folded ends of the film 3 onto part of the tubular film length wrapping each tray 2. In this case, since the tray 2 is subjected to the weight of a roller 1 35 supported so as to be vertically movable on the housing 10 through parallel links 134, both the folded ends of the film length 3 are sealed close to the bottom surface of tray 2.Also, where a hot air tunnel 1 36 is provided at the downstream side of roller 1 35 and a shrinkage film is used, the film can be heated and contracted at the hot air tunnel 136, thereby effecting shrink wrapping. A hot air tunnel is, however, not used when packing articles, such as perishable foods, which may be adversely affected by heat.

As may be seen from the above, the packaging apparatus of the invention comprises a tray transport mechanism 22 having a conveyor 12 and film stretching belts 57, film cutting means 63, first and second air suction channels 64 and 65 including first and second dampers 90 and 98, and roller means 100, so that the film 3 wrapping the trays is cut and the leading and taiiing ends of tubular film lengths are folded against the bottom surface of each tray and effectively stretched by means of dampers and air flows as explained above, whereby the packing apparatus is advantageous in that the trays are continously transported and also can be packed by the film without creating wrinkles.

Claims (9)

1. A packaging apparatus for wrapping trays containing articles in flexible and stret chable film, which apparatus comprises a conveyor for transporting said trays, a supply means for supplying to said trays transported by said conveyor, in use of the apparatus, a band of said film at a speed equal to said conveyor so as to wrap each of said trays in a tubular-shaped length of said film, a cutting means for cutting said tubular film wrapping each of said trays between successive trays in the transport direction thereof, and a folding means for folding downwardly the leading and trailing ends of respective film lengths cut by said cutting means and sealing said ends to the bottom surface of each of said trays, wherein is provided a first air suction channel for turning downwardly the leading end of said film length cut by said cutting means and a second air suction channel for turning downwardly the trailing end of said film length cut by said cutting means, said air suction channels being disposed between said successive trays in the transport direction thereof with respect to said cutting means and provided with air inlets open upwardly respectively and with a first film holding means and a second film holding means which are provided within said air suction channels and hold therein the leading and trailing ends of said film lengths taken in through respective ones of said air inlets a side-belt means which sandwiches laterally said trays covered by said tubular film and forcibly transports them so that said trays are allowed to pass through said cutting means and first and second air suction channels thereby to fold downwardly towards the bottom surface of each of said trays the leading end of said film held by said first film holding means within said first air suction channel, and a roller means of endless-belt type which moves at a higher speed than said side-belt means thereby to fold downwardly towards the bottom surface of each of said trays, the trailing end of said film held by said second film holding means within said second air suction channel, said roller means providing an opening registering with said air inlet of said second air suction channel.

2. A packaging apparatus according to claim 1, wherein said first air suction channel is provided in the vicinity of said air inlet with a first bypass port and within said first air suction channel with a first damper which normally closes said first bypass port and swings to open said first bypass port when said film to be cut by said cutting mechanism closes said air inlet, whereby the leading end of said film taken in through said air inlet is held between said damper and the inner wall of said first air suction channel.

3. A packaging apparatus according to claim 1 or claim 2, wherein said second air suction channel is provided in the vicinity of said air inlet with a second bypass port, and with a second damper which is provided in said second air suction channel and normally closes said second bypass port and opens said port by suction when said air inlet is closed by said roller mechanism, so that the trailing end of said film taken in through said air inlet is held between said second damper in the inner wall of said second air channel.

4. A packaging apparatus according to any one of claims 1 to 3, wherein said cutting means is provided with a cutting blade, a filmresistance-giving plate which is supported so as to be capable of advancing or retreating with respect to said cutting blade and gives to the leading end portion of said film held by said film holding means resistance against movement of said film caused by said side belt mechanism, and an upper cutting element for pressing said film with respect to said cutting blade and press-cutting said film in co-operation with said cutting blade.

5. A packaging apparatus according to claim 4, wherein said cutting blade comprises a blade of saw-tooth edge and is fixed to the front wall of said first air suction channel with respect to the transport direction of said trays.

6. A packaging apparatus according to any one of claims 1 to 5, wherein at the upper portion of said first air suction channel is provided, a roller rotatable at high speed by said side belt means to feed the leading end of said film into said first air suction channel.

7. A packaging apparatus according to any one of claims 1 to 6, wherein said roller means is provided with a belt disposed so as to surround said second air suction channel.

8. A packaging apparatus according to claim 7, wherein said belt comprises a pair of laterally spaced endless chains and a plurality of rollers bridging across said chains and disposed closely adjacent successive ones thereof except at said opening which is constituted by a gap between two successive said rollers.

9. A packaging apparatus according to any one of claims 1 to 8, wherein said means for wrapping said trays into said tubular film comprises a pair of film conveyors provided with film holding clips and clipping said film at both lateral sides and supplying to said trays said film laterally slantwise and downwardly, a film stretching belt means positioned inside said film conveyors and outside said trays thereby to push down said film, and a tubular-film making means positioned at the downstream side of said film conveyors and in front of each of said trays in the transport direction thereof so that said film released from said clips at said film conveyors is folded at both lateral sides together with each other and towards the bottom surface of each of said trays so as to form a tubular film shape around said trays.

1 0. A packaging apparatus substantially as described hereinbefore with particular reference to, and as illustrated by the accompanying drawings.