US3224163A

US3224163A - Package sealer

Info

Publication number: US3224163A
Authority: US
Inventors: Ii Smith G Ray
Original assignee: GT SCHJELDAHL CO
Current assignee: GT SCHJELDAHL CO
Priority date: 1962-01-15
Filing date: 1962-01-15
Publication date: 1965-12-21
Anticipated expiration: 1982-12-21

Description

6 Sheets-Sheet l Dec. 21, 1965 s. G. RAY

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United States Patent O 3,224,163 PACKAGE SEALER Smith G. Ray II, Northfield, Minn., assigner to G. T. Schjeldahl Company, Northfield, Minn., a corporation of Minnesota Filed lian. 1S, 1962, Ser. No. 177,689 19 Claims. (Cl. S21- 329) This invention relates to a package sealing apparatus and more particularly to a packaging machine for heat sealing the lid .portion of a thermoplastic container to the tray portion thereof.

The invention is primarily concerned with sheet plastic containers made of bi-oriented thermoplastic material of inexpensive nature, but having special attributes such as transparency, water resistance, resilience, toughness, chemical purity so as not to contaminate products contained therein, and so forth. Bi-oriented thermoplastic material is easy to melt as a rule but the material then shrinks and may become brittle, discolored and warped. Thus where a container of polystyrene has a tray and lid portion which are heat sealed together by simply contacting and melting the edges, a warped and brittle joint is formed. If the tray or lid is distorted by a product which is irregular in shape or is too big for the package, then the problems are still greater and an imperfect seal can easily result. A special problem arises in connection with poultry and like products which are irregularly shaped and sized and which are intended to present a pleasing appearance, even when frozen to preserve the product. It has been suggested in prior art that a lid and container be so constructed as to interfit or telescope, thus making it possible for the package to be sealed at different volume levels, depending on the quantity of product placed therein. In addition to the previously mentioned problems, there is now the additional problem of how to give a uniform and pleasing appearance to the sealed joint when the edges overlap to different degrees and present an unfinished effect.

It is within the contemplation of this invention, and a general object thereof, to overcome the aforementioned problems and to provide an efllcient apparatus for sealing filled packages of the type which utilize a tray and lid fabricated from bi-oriented thermoplastic sheet stock.

Another object of the invention is to provide an apparatus for the purpose described which will utilize heat sealing dies constructed to accommodate two-part prefabricated containers wherein the same apparatus can accommodate different depths of product within the container.

A further object is to provide an apparatus which, prior to sealing, will conform a premolded container, without distortion, to the shape of a product contained therein and will substantially expel the air therefrom to obtain a compact and solid package unit presenting a pleasing appearance and rendering the package particularly adaptable to freezer techniques in the case of food products such as poultry.

A still further object is to provide a sealing apparatus for lidded containers of bi-oriented thermoplastic material wherein means are provided for sealing the marginal surfaces of the lid and container together under high pressure, then quickly rolling the flange inwardly to produce a neat and strong joint.

Still another object of the invention is to provide a sealing apparatus for the purpose described wherein upper and lower die assemblages are employed and a heat differential exists between them such as to cause the bioriented thermoplastic material to shrink to a greater degree in a one inch margin of the lid and container than in the other whereby the sealed flange will tend to curl and assist the scooping or rolling action thereof as the apparatus completes the sealing of the package.

"ice

A still further object of the invention is to provide die assemblages of simple design wherein a package may be completely encompassed under pressure, a portion of the assemblages having independent biasing action following the high pressure heat sealing of the flanged margins of the package to effect rolling of the flanges and to assist in the ultimate ejection of the package from the apparatus.

These and other objects and advantages of this invention will more fully appear from the following description, made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views and in which:

FIGURE 1 is a side elevation of the sealing mechanism with one package having a lid or cover placed thereon and being in readiness to be sealed and another package positioned in readiness to have the cover placed thereover. The upper die assemblage has just started its descent toward the package. Portions of the view are sectioned to better show the internal construction of the parts and others are segmented and shown in dotted line configuration;

FIGURE 2 is a fragmentary vertical section of push rod and toggle mechanism taken on the line 2-2 of FIG- URE 1 and looking in the direction of the arrows;

FIGURE 3 is a somewhat enlarged view of the upper and lower die assemblages in partial vertical section, the position of the upper die being the same as that on FIG- URE 1;

FIGURE 4 is a view similar to that of FIGURE 3 showing the upper die extended to its lowermost sealing position to effect heating and compression of overlapping flanges of the thermoplastic package;

FIGURE 5 isa still further view similar to that of FIG- URES 3 and 4 showing both the upper and lower dies in partially raised condition;

FIGURE 6 shows the upper die in completely raised condition with the flange curling plates in withdrawn position and with the completed package ejected from the die;

FIGURE 7 is a top plan view of the rotary arm and lower die assemblages;

FIGURE 8 is a diagrammatic plan view of the flange curling plates showing their relative movement;

FIGURE 9 is a perspective view of a representative package which has been completely sealed, portions of the lid and container being cut away to show the character of the sealed flanges;

FIGURE l() is a schematic representation of the electrical system which operates the sealing mechanism;

FIGURE l1 is an enlarged detail in fragmentary view of the curling procedure following the sealing of the package flanges wherein both the upper die and the basket are simultaneously rising;

FIGURE 12 is a view similar to that of FIGURE l1 showing an instantaneous subsequent position of the parts wherein the die continues its movement upward and the basket is being retracted from the container, and

FIGURE 13 is a view similar to those of FIGURE 1l and FIGURE 12 wherein the upper die continues its upward movement and the spring-pressed pressure pad has caused the container to press downwardly against the curling plate to complete the curling of the sealed flanges of the container.

With continued reference to the drawings, mechanisms unessential to the present invention are excluded or are set forth schematically together with the electric circuit for the apparatus as shown in FIGURE l0.

The invention in its broadest concept and sequence of operations comprises a supporting structure 10 upon which is rotatably mounted a rotary arm element 11 which in turn carries a pair of identical lower die assemblages 12. Adjustably fixed with respect to the support 10 is a mounting plate 13 having secured thereto a power means 14 for pushing an upper die assemblage 15 convergently and divergently from a lower die assemblage 12 to effect sealing of a package 16 held by the lower die assemblage. Cam elements 17 are secured to the mounting plate 13 for actuating flange rolling mechanisms 18 as will be described in detail later in this specification. Generally speaking, the upper and lower die assemblages converge so as to first expel air from the container 16 and to conform the container closely about a product contained therein and then the peripheral margins of the lid and container portions are heat sealed together in a retained manner to prevent shrinkage and warping, following which the flange rolling blades 18 cause the sealed flange to be curled inwardly irrespective of the relative positions of the peripheral margins of the respective lid and contamer portions. The completed package is then ejected from the upper die assemblage preparatory to indexing the rotary arm 11 and presenting another lower die assemblage 12 with an unsealed lidded centainer placed therein.

Now referring specifically to FIGURE; -`3,the xed support comprises a portion of a machine assembly not essential to the present case but is conveniently located with respect to human operators or automatic equipment (not shown) for placement of containers of thermoplastic sheet material comprising a tray or container portion 19 having a peripheral margin 20 and a lid portion 21 having a mating margin area 22 so formed as to provide a telescoping tit, the marginal arca 22 constituting a skirt which overlies and interfits with the area 20. The combined marginal or

skirt areas

20 and 22 are hereinafter referred to as the ange 23. It is contemplated that a wide variety of products may be packaged in the lidded container and may extend to such food products of irregular shape and size as fowl 24. The invention is particularly useful as noted hereinabove in handling difficult bi-oriented sheet plastic containers such as those `made from polystyrene and the like.

The support 10 has an indexing motor 25 which may be secured directly thereto by such means as bolts 26 and has an upwardly extending shaft 27 rotatably passing through the support v10 as shown. A pinion lgear l25:5 is secured to shaft 27 and is drivably connected with the gear 29 which in turn is secured to the hub 30 of the rotary arm 11. The hub 30 is rotatably mounted upon a rigid shaft 31 which in turn is secured to the mounting block 32 lixed to the support 10 as shown.

The rotary arm 11 has a pair of radially extending portions 33 of each of which supports a lower die assemblage 12. Also secured to the radial portions 33 are locating heads 34 which in turn are adapted to be guided into and to bear against stabilizing blocks 35 for locating and supporting the lower dies beneath the upper die assemblage prior to and during the lower die assemblage 12. Also formed at the outer ends of each of the radial portions 33 is switch actuating lobe 35, the function of which is to operate

switches

37 and 38 for purposes subsequently described in detail.

Also secured to the hub 30 and extending upwardly therefrom is a sleeve 39 which rotates with the rotary arm 11 and surrounds the fixed shaft 31 as shown in FIGURE l. The sleeve 39 has a short adapter sleeve 41) interitted therewith and adjustable to various heights and various arcuate positions by means of screw 41 which passes through sleeve 39 and is ixedly secured to the adapter sleeve 40 at any one of a number of threaded openings 42 to adjust the height of adapter 4t) and further may pass through any of a number of horizontally spaced openings 43 in the sleeve 39.

At the upper end of the adapter sleeve 40 is a cam 44 which rotates with the rotary arm 11 and is provided with lobes 45 for a purpose to be subsequently described. The fixed shaft 31 extends upwardly through the adjustably fixed plate 13 and a boss 46 secured to said plate 13 and a cap screw 47 is threadably received in the end thereof so as to secure bracket 48 to shaft 31. As a position outwardly from the cap screw 47 a stop screw 49 is threadably received and is provided with a pair of nuts 5t) for adjustably varying the length of screw 49 to determine the proper position at which the plate 13 should be adjusted for varying conditions of packages 16, such as would affect the height of the dies.

Referring now to FIGURE 3, the lower die assemblage 12 has a lower die support plate 51 which is fastened to the radial arm portion 33 with a bushing 52 secured centrally thereof for the purpose of slidably receiving a plunger 53. A collar 54 is xed to plunger 53 and bears against a compression spring 55 which is abutably received within the bore 56. At the upper end of shaft 53 is secured a basket 57 by means of a screw fastener 58 countersunk in the inside bottom 59 of the basket. The basket 57 has a bottom plate 60 and upstanding side portions 61 which terminate upwardly in an edge 62. The edge 62 is adapted to support the thermoplastic container 19 inwardly of the skirt or peripheral margin 20 and, with the spring 55 in its extended position, preventing contact and premature heating of the container 19 except at the very peripheral area 20 which is desired to be held. It will be noted that a plate 63 is removably attached to the inner bottom surface 59 of the basket 57 by means of countersunk screws 64 as shown. Whenever a container of greater depth is employed, the plate 63 may be removed to change the total depth of the basket and hence accommodate a larger container. The basket slides vertically against lower heating die 65 at the inner surface 66 thereof and may be moved both upwardly and downwardly to a limited extent as will be subsequently described. Lower die 65 is provided with a heating element 67 over which a heater cover plate 68 is secured. Heat is transferred from heating element 67 to the lower heating die 65 and is intended to be maintained at a proper temperature all during operation of the apparatus. The lower heating element 67 is provided with electrical energy through wires 69 which wires may be connected with a commutator or other means (not shown) which will permit the continuous energization of the element '67 even though the lower dies themselves rotate intermittently during use. An air operated booster head '70 is adapted to move vertically through the supporting structure 10 and is aligned with the bottom of plunger 53 as shown. An air cylinder 71 is of conventional double acting character and, through application of air to tube 72 will retract the booster head 70 and upon application of air to the line 73 will cause the booster head 70 through the conventional cylinder arrangement to be extended upwardly and to raise the plunger 53 and its associated basket 57 as will be subsequently described.

Referring again to FIGURES l-3, the power means 14 for raising and lowering the upper die assemblage 15 constitutes a similar pneumatic device comprising a cylinder 74 and a cylinder rod 75 which extends slidably through the adjustable plate 13 and bushing 76 secured therewith. When air is supplied through line 77, the piston rod 75 is caused to move downwardly and when air is supplied through the line 7 8, the piston rod 75 is caused to move upwardly. The upper die assemblage 15 has an upper die support casting 79 which is secured to the piston rod '75 and travels upwardly and downwardly therewith as the piston and cylinder are actuated as previously noted. Received within the upper die casting 79 is a pressure pad 80, the inner surface 81 of which is contoured to t and press against the lid portion 21 of the container and to expel air from the space S2 as the upper die assemblage 15 descends. Pressure pad 80 is provided with compression springs S3 which are positioned over pegs 84 and are retained in socket caps 85 secured to the top of the upper die casting 79. Bolts 36 are secured to the pressure pad 81 and are slidably received in the upper die casting '79 with bolt heads 37 normally in abutment with the die casting 79 to limit the downward movement of pressure pad under the influence of compression springs 83.

Also associated with the upper die casting 79 is a pair of guide pins 88, one forwardly and one rearwardly of the piston rod 75 and partly cut away as shown in FIG- URE 1 to expose other portions of the upper die assemblage. The guide pins S8 are slidably received in bushings 89 and assist in maintaining the upper die assemblage 15 in alignment as the piston rod 75 lowers the upper die 15 toward the lower die assemblage 12. The arrangement of the guide pins 88 and the piston rod 75 is better shown in the segmental view of FIGURE 2.

In order to limit the upward movement of the upper die assemblage 15, a toggle 90 is pivotally secured at 91 to a support block 92 in turn secured to the adjustably Iixed mounting or support plate 13. The toggle 90 is also provided with a roller 93 mounted adjacent its lower end and adapted to contact a bumper stud 94. The two toggles 90 are biased to the right as shown in FIGURES 1 and 3 by a tension spring 95 interposed between the toggle and a spring post 96 secured to the plate 13. A push rod 97 is slidably received in gib block 98 and is provided at its forward end with a forked portion 99, each fork in turn being provided with an end roller 100 which abuts against each toggle 90 in the position shown in FIGURE 2. The opposite end of the push rod 97 has a cam follower 101 which rides against the cam 44 and is adapted to hold the toggles 90 in their vertical position at the low portion of cam 44 and are adapted to push the toggles against the action of spring 95 whenever the lobe 45 engages cam follower 101 and thereby permits the upper die to rise to a position above that in FIGURES 1 and 2 when the cylinder 14 exerts an upward force on the piston rod 75.

Secured to the upper die casting 79 is the heater casting 102 which retains the upper die heater element 103 as shown in FIGURE 3. The heater element 103 is removably secured in place by a heater plate 104 and the element 103 is energized through leads 105, the circuitry of which will be detailed later. The upper die proper is designated as 106 and is angulated outwardly and downwardly to conform with a similar outward and downward angulation of lower die 65. The upper die 106 is also adapted to be continuously heated during operation.

Underlying the upper die and closely associated therewith as shown particularly in FIGURES 3 and 11-13 is a flange rolling blade 107, one of said blades 107 being disposed at each side of the die and arranged with two long blades in opposed relation and two short blades also in opposed relation, all of said blades functioning the same and simultaneously. Details of the mechanisms associated with all of the blades are not shown since they are merely duplicative. The flange rolling blades 107 constitute an important part of the invention since they cause the flange portion 23 of the package to be curled back in a manner such as to strengthen and improve the appearance of the finished sealed package. Each of the flange rolling blades is provided with a curved area 10S which causes the flange 23 to curl subsequent to the sealing of the marginal areas of the lid and container portions. The llange rolling blades are adapted to reciprocate inwardly and outwardly from the upper die cavity of pressure pad 80 and the manner of reciprocation is timed in such a manner as to achieve several important functions. To this end each of the llange rolling blades 107 is secured to a mounting block 109 which in turn is pivotally connected at 110 to a link 111, the latter being pivotally mounted at 112 to the blade hanger support 113 as shown in FIGURE 3. A cam rocker arm 114 is also pivotally secured at 115 to the blade hanger support 113 and further is pivoted in parallelogram fashion at 116 to the mounting block 109. At the upper end of the cam rocker arm 114 is rotatably mounted a cam follower 117 and it is obvious that whenever the cam follower 117 is moved inwardly toward the upper die cavity defined by the inner 6 surface 81 of pressure pad 80 the flange rolling blade 107 will be retracted.

To effect the advance and retraction of blade 107, a cam brackt 118 is lixedly secured by such means as bolts 119 to the upper support plate 13. The cam bracket 118 has a grooved cam 120 which is directed inwardly at its upper and lower ends but lies at its outer position in the intermediate portion of its length as seen particularly in FIGURE 3. Of the three cam positions, the uppermost is designated as 121, the intermediate as 122 and the lower as 123.

As a part of the electrical system which operates the apparatus, a double switch 124 is mounted to mounting plate 13 and has a switch arm 125 adapted to be contacted by a switch actuating post 126 secured to the upper die casting 79. Also included in the electrical system is a timer 127 which can be preset to operate a switch mechanism as will be described with a preset interval of time between operations.

In the use and operation of the package sealer, reference is now made to FIGURE l0 in conjunction with the other views which show the structural and mechanical relationship of the various parts. A sourceA of electrical energy designated by the

lines

123 and 129 is utilized for both actuation .and heating of the elements as will now be described. A switch 130 is closed to energize the heating element 103 associated with the upper die and a thermostat 131 may be adjusted to hold the element at a proper temperature above the melting point of the particularly bi-oriented plastic material employed. Similarly, switches 132 are closed to energize the heating elements 67 associated with each of the lower die assemblages 12. Thermostats 133 are set to hold the lower heating elements 67 at constant temperatures above the melting point of the bi-oriented plastic material and preferably at a temperature higher than that of the upper heating element 103 so as to assist the curling of the flange portion of the package as has been heretofore described. With the heating elements energized, a container 19 is placed in the basket 57 of a lower die assemblage 12 and an article to be packaged, such as fowl 24, is placed within the tray or container 19. The marginal area 20 will now overlie the side portion 61 of the basket 57 and be maintained slightly above the hot die 65 by virtue of the compression spring 55. A lid 21 is now placed over the fowl 24 with its marginal area 22 is telescoping engagement with the corresponding marginal area 20 of the container 19. For purposes of describing the operation herein, it will be assumed that an unsealed package lies beneath the upper die in readiness to be sealed and that the operator is in the process of positioning another package to be sealed in the opposite lower die assemblage. Timer 127 is set to give a desired time lapse each time the timer is energized. A switch 134 may be moved from manual contacts 135- 1 36 to close contacts 137-138 to energize a circuit from line 128 through lead 139 to timer actuator 140, through switch 37, which is now closed because the rotary arm element 11 is in sealing position with its cam lobe 36 maintaining the switch closed, then through lead 141 to the other supply line 129. At the same instant a parallel circuit is established from the lead 139 through wire 142 to the common terminal 143 through switch arm 144 and conductor 145 since cam lobe 146 on the timer is at its start position. The current continues from conductor 145 to solenoid 147 and thence through the closed switch 37, through wire 141 and to the line 129. The timer now begins to time out and the energization of solenoid 147 causes valve 148 to open a line from an air pressure source 149 to tube 150, through three-way ball check valve 151 and thence to the conduit 77 which causes the cylinder 74 to depress the piston rod 75 downwardly. It will be remembered that the piston rod 75 was attached to the upper die assemblage 15 as shown in FIGURE l and hence the die assemblage will begin its descent. FIGURE 1 depicts the condition where the upper die assemblage has already descended to the point where toggle 90 has assumed a vertical position but the switch 124 is still maintained such that switch arm 125 has not as yet reached its normal position. However, upon continued downwardly travel of the upper die assemblage 15, the switch arm 125 will be permitted to lower and will close the switch arm 152 and open switch arm 153 which constitute the double switch 124. However, since the timer switch arm 144 remains out of contact with line 154, the actuation of switch arm 125 makes no difference at thisV point. The upper die assemblage 15 continues its downwardly descent until the pressure pad 80 contacts the lid 21 and exerts pressure thereon to cause expulsion of air as previously noted. The upper die yassemblage 15 then continues still further downward, depressing the basket 57 during the air expulsion process and ultimately causes the angulated and upper die 106 to wedge against the telescoped or overlapped

edge margins

20 and 22, squeezing and retaining them under high pressure while sub` jecting ,them to fusing t-empenatures as shown in FIGURE 4. It will be noted that the flange rolling blades are now retracted since the upper die has reached its lowermost position. The fusing of the edge margins into a sealed iiange takes place over a few seconds and then the lobe 146 of the timer motor 140 reaches its stop position which depresses switch arm 144 (FIGURE 10) and the preconditioned circuit through switch 152 is now completed, energizing conductor 155 and solenoid 156 which in turn actuates valve 157 to cause air pressure from a source (not shown) to enter through conduit 158 and pressurize the line 73 which in turn causes the piston assemblage 71 to project its booster head 70 upwardly in contact with the plunger 53 as shown in FIGURE 4. At the same time the switch arm 144 opened the `circuit to solenoid 147 causing a reversal of air pressure from conduit 149 through valve 14S, thence through tube 78 into main cylinder 74, out through the tube 77 through the three-way ball check valve 151, through tube 150 and through valve 148 to the air exhaust line 159. The main cylinder 74 will thus cause the piston rod 75 to rise carrying the upper die assemblage 15 with it. As the upper die rises, the booster head 70 will cause the basket 57to overcome the pressure of springs 83 and maintain the pressure pad at its upper position for a short period of time. The upper dies assemblage together with the basket and sealed package then rises from the position of FIGURE 4 to that of FIGURE 5. It will be noted that the rocker arms 114 have been caused to push the flange rolling plates 107 inwardly since the earn followers 117 have now reached the intermediate portion 122 of grooved cam 12). Since the upper die assemblage 15 has been separated from the lower die 55, the still hot yand soft flange 23 extends downwardly and when treated with a temperature differential as noted hereinbefore will cause the iiange to assume an inwardly curved appearance as is evident from FIGURES 5 and l1. Now as the piston rod 75 causes the upper die assemblage to continue to rise, the basket 57 will reach the upper limit of its travel since collar 54 (FIGURE 3) abuts the bushing 52 and prevents further upward travel of the basket 57. Since the basket was raised under the influence `of booster head 70 which overcame the force of compression springs 33 which bias the pressure pad 8@ downwardly, the pad has remained in upper position to this point. However, upon continued rise of the upper die assemblage, the compression springs l b surface 108 of the fiange rolling blades 107. The initial rolling action is depicted in FIGURE 12 and FIGURE 13 shows the l'inal roll of liange 23 as the pressure pad 80 bottoms out and the heads 87 of bolts 86 abut the top of the upper die casting 79. The upper die assemblage finally reaches the position of FIGURES l and 3 wherein the toggle bumper stud 94 strikes the toggle 91B and is prevented from further upward movement. At this point the switch arm of double switch 124 is again actuated and switch 152 becomes open and 153 becomes closed (FIGURE 10). Since switch arm 144 has remained in contact with line 154, the closing of switch 153 energizes the indexing motor 25 which in turn causes the rotary arm element 11 to begin its rotation. The instant the arms 33 begin to rotate, the carn lobe 36 will permit switches 37 and 3S to assume their normal condition. Thus, switch 37 will open, de-energizing switch motor 1411 and thereby permitting the cam 146 to assume its starting position which also causes switch arm 144 to contact the line 145, but the solenoid 147 is not energized at this point because switch 37 remains open. The other switch 38, however, is now permitted to close upon the movement of cam lobe 36 and a circuit is established through conductor 161i, solenoid 161 to line 129. The energizing of solenoid 161 causes an air pressure source from tube 162 to pass through valve 16T, through conduit 164 into the bottom of three-way ball check valve 151 which raises the ball 165 therein, closing off line 150 and causing air of moderate pressure to enter line 77 and form an air cushion in the upper portion of main cylinder 74. All this occurs before the rotary arm element has advanced 90 degrees in its rotation. However, as it reaches 90 degrees from its sealing position, the cam 44 will have turned with a rotary indexing arm 11 so that its lobe 45 will strike cam follower 101 and move the push rod 97 to the left as shown in FIGURE 6. The movement of push rod 97 will cause the toggle 90 to snap over its dead-center position and release the upper die assemblage 15 which still has relatively higher air pressure exerting an upward force on piston rod 75. The continued cushioned movement of the upper die assemblage against the low pressure air volume at the upper side of the main cylinder 74 causes the upper die assemblage to raise to its fullest extent, bringing the cam followers 117 to the upper portion 121 of grooved cams 120, thus again retracting all of the iiange rolling bladges 107. Since at this point only the blades 1137 retain the sealed and rolled packages against the downwardly biased pressure pad 80, the sudden withdrawal of blades 107 permit the forcible ejection of the package in a downward direction. The package will, of course, fall upon ya catch table 166, each of which is supported by arms 167 and rotate with the lower die assemblages. The finished package (FIGURE 9) may then be removed from the tray as the rotary arm element continues its indexing movement to a full degree turn.

Whenever a package to be filled neath the upper die assemblage 15 package into sealing position, the switch 134 is moved from `its automatic position to the manual position, opening the switch contacts 137-138 and closing the contacts 13S-136. With the circuit thus preconditioned, a manual again actuates the

switches

37 and 38.

It will, of course, be understood that various changes may be made in the form, details, arrangements and proportions of the parts without departing from the scope of this invention as set forth in the appended claims.

What is Iclaimed is:

"1. A heat sealing apparatus for packaging products in lidded containers .fabricated of thermoplastic material, said Iapparatus comprising,

(a) 'a fixed support,

(b) a lower die assemblage carried by said fixed support and adapted to receive a container with its contents,

(c) an upper -die assemblage mounted over said lower die assemblage and convergently movable theretoward,

(d) :said -upper die assemblage having a portion adapted G) to receive a lid for said container and to press thereagainst during convergent movement of said upper `and lower die assemblages,

(e) a heated die on said lower die assemblage having an outwardly facing surface adapted to surround said container and to contact the peripheral margin of said container,

(f) a heated die on said upper die assemblage having an inwardly facing surface adapted to surround said lid and to contact the peripheral margin of said lid, .and

(g) power means urging said upper and lower die assemblages convergently iirst to press said lid against its contents whereby to expel air from the container, then to press the respective outwardly and inwardly facing surfaces together and thereby to yheat seal the respective peripheral margins of the lid and container.

2. A heat sealing apparatus for packaging products in lidded containers fabricated `of thermoplastic material, said apparatus comprising,

(a) a fixed support,

(b) a lower die assemblage carried by said lixed support and adapted to receive a container with its contents,

(c) `an upper die assemblage mounted over said lower die assemblage and convergently movable theretoward,

(d) said upper die assemblage having a spring loaded portion adapted to receive a lid for said container and to press thereagainst during convergent movement of said upper and lower die assemblages,

(e) a heated die on said lower die assemblage adapted to surround said container and to contact the peripheral margin of said container,

(f) a heated die on said upper die assemblage adapted to surround said lid and to contact the peripheral margin of said lid, and

g) power means urging said upper and lower die assemblages convergently first to engage said lid with said spring loaded portion and to press said lid against its contents whereby to expel air from the container, then to press together and heat seal the respective peripheral margins of the lid and container, said power means having a force greaterthan that of the spring loading of said upper die assemblage portion.

3. A heat sealing apparatus for packaging products in lidded containers fabricated of thermoplastic material, said apparatus comprising,

(a) a iixed support,

(b) a contoured lower die assemblage carried by said support and adapted to receive a similarly contoured container with its contents,

(c) an upper die assemblage mounted over said lower die assemblage and convergently movable theretoward,

(d) `said upper die assemblage having a contoured portion adapted to receive .a pre-contoured lid for said container and to press thereagainst during convergent movement of said upper and lower die assemblages,

(e) `a heated die on said lower die assemblage land having an outwardly facing surface adapted to surround said container and to contact the peripheral margin of said container,

(f) a heated die on said upper die assemblage and having an inwardly facing surface adapted to surround said lid and to contact the peripheral margin of said lid, and

(g) power means urging said upper and lower die assemblages convergently irst to press said lid against its contents whereby to expel air from the container, then to press the respective outwardly and inwardly facing surfaces together and thereby to heat seal l@ the respective peripheral margins of the lid and coritainer.

4. A heat sealing apparatus for packaging products in lidded containers fabricated of thermoplastic material, said apparatus comprising,

(a) a fixed support,

(b) a contoured lower die assemblage carried by said iixed support and having a basket portion adapted to receive a similarly contoured container with its contents,

(d) said upper die assemblage having a contoured portion adapted to receive a pre-contoured lid for said container and to press thereagainst during convergent movement of said upper and lower die assemblages,

(e) a heated die on said lower die assemblage and having an outwardly facing surface adapted to surround said container and to contact the peripheral margin of said container,

(f) a heated die on said upper die assemblage and having an inwardly facing surface adapted to surround said lid and to contact the peripheral margin of said lid,

(g) power means urging said upper and lower die assemblages convergently first to press said lid against its contents whereby to expel air from the container, then to press together the respective outwardly and inwardly facing surfaces and thereby to heat seal the respective peripheral margins of the lid and container, and

(h) means provided in said basket portion of the lower die assemblage for receiving containers of different depths.

5. The apparatus of claim 4 wherein said means in said basket portion of the lower die assemblage constitutes a removable plate secured to the inner bottom surface of the basket.

6. The heat sealing apparatus of claim 1 and (a) a flange rolling blade underlying the heated die on said upper die assemblage and being extensible to underlie the sealed peripheral margins of said lid and said container and curl the same inwardly toward said container.

7. The apparatus of claim 6 for packaging products in lidded containers fabricated of bi-oriented thermoplastic material wherein said lower heated die is maintained at a higher temperature than the upper heated die.

8, A heat sealing apparatus for packaging products in lidded containers fabricated of thermoplastic material, said apparatus comprising,

(a) a fixed support,

(b) a lower die assemblage adapted to receive a container with its contents,

(d) said upper die assemblage having a portion adapted to receive `a lid for said container and to press thereagainst during convergent movement of said upper and lower die assemblages,

(e) a heated die on .said lower die assemblage adapted to surround said container and to contact the peripheral margin of said container, and

(f) a heated die on said upper die assemblage adapted to surround said lid and to contact the peripheral margin of said lid,

(g) the heated die of said lower die assemblage having a continuous peripheral surface angled outwardly and downwardly said upper heated die of the upper die assemblage also having a continuous peripheral mating surface which is angled outwardly and downwardly whereby to exert a wedging pressure against the sealed flange of the lid and container margins when the die assemblages are brought together.

9. A heat sealing apparatus for packaging products in containers fabricated from two pieces of thermoplastic material, one of `said pieces constituting a tray formed with a downturned marginal portion and the other piece constituting a lid formed with a downwardly extending marginal portion for overlying and interfitting with the marginal portion of said tray, the apparatus comprising:

(a) a lower die assemblage;

(b) an upper die assemblage;

(c) power means for raising and lowering said upper die lassemblage with respect to said lower die assemblage;

(d) a heated ldie on said lower die assemblage formed with an upstanding wall having a vertical inner surface and -an ang-ulated `outer surface providing a relatively narrow upper edge;

(e) a basket formed with an upstanding wall having a vertical outer surface and a centrally disposed recess for the accommodation of at least the lower part of the product to be packaged, said upstanding wall on the basket forming a relatively narrow upper edge;

(f) spring means normally biasing said basket upwardly to an elevation such that the upper edge thereof is at least the same height as the upper edge on said lower die, said edges when at the same height being adapted to extend into the region between the inner surface -of said downturned marginal portion and the outer surface of said tray;

(g) a heated die on said upper die assemblage disposed for movement with said upper die assemblage having an inwardly facing lower outwardly and downwardly angulated surface complementing the angulated outersurface of the die on said lower assemblage and a vertical inner surface above said lower angulated surface;

(h) a pressure pad guided for reciprocal movement within the confines of said vertical .surface on said upper die;

(i) spring means on said upper die assemblage normally biasing said pressure pad downwardly so that the bottom of said pad is at the same approximate elevation as the bottom of the angulated surface on said upper die,

(j) whereby when said power means lowers said upper die assemblage said pressure pad will yieldably press against said lid and said upper die will press the inner surface of the marginal portion on said lid against the outer surface of the marginal portion on said tray to initiate a heat sealing of said marginal portions to form a flange when the upper edges of said lower die and said basket are at the same height.

it). The heat sealing apparatus of claim 9 and (a) power means for raising said basket after said marginal portions have been heat sealed to overcome the Ibiasing action of the spring means on said upper die assemblage to force said pressure pad upwardly relative to said upper die rand .to also move the sealed marginal portions away from said lower die.

11. The heat sealing apparatus of claim 1t) and (a) means for actuating said first power means to raise said upper die to separate said upper die from said basket.

12. The heat sealing apparatus of claim 11 and (a) a plurality of flange rolling blades on said upper die assemblage;

(b) means for moving said flange rolling blades into a subjacent relation with said flange formed from said marginal portions before said first power means is actuated to raise said upper die assemblage,

(c) whereby said fiange is rolled inwardly by said ange rolling blades as said upper die assemblage rises, `said spring means on said upper die assemblage pressing said pressure pad against said flange rolling blades.

t3. The heat sealing apparatus of claim 12 in which:

(a) said flange rolling blades are formed with curved are-as for engaging said flange to facilitate the rolling thereof as said upper assemblage is raised.

lll.. The heat sealing apparatus of claim 12 and (a) cam means actuated by movement of said upper assemblage to a predetermined elevation to cause said means for moving said flange rolling blades to retract said blades when said upper assemblage has been raised to a-predetermined height.

15. The heat sealing apparatus of claim 14 and (a) shiftable limit means for first preventing said upper assemblage from reaching said predetermined elevation to thereby prevent actuating of said cam means and retraction of said flange rolling blades when said upper assembly is below said predetermined elevation, and

(b) means for shifting said limit means to permit said upper assemblage to reach said predetermined elevation to cause actuation of said cam means and retraction of said blades to permit downward ejection of the packaged product.

le. A heat sealing apparatus for packaging products lidded containers fabricated of thermoplastic material,

said apparatus comprising:

(a) a first die assemblage;

(b) a second die assemblage;

(c) power means for moving said second die assemblage toward and away from said first assemblave' (d) -a first heated die on said first assemblage; a

(e) a basket member reciprocally movable relative to said first heated die;

(f) means on said first assemblage normally biasing said basket member toward said second die assemblage;

(g) a second heated die on said second assemblage cooperable with said first die to heat seal marginal portions of a container and lid t-o be placed thereon' h) la pressure pad reciprocably movable relative td said second heated die, and

(i) means biasing said pressure pad toward said first assemblage, said last-mentioned biasing means beine capable of overcoming the action lof said first-menotioned biasing means when said power means causes said second assemblage to be moved sufiiciently toward said first assemblage.

17. The heat sealing apparatus of claim 16 in which:

(a) said heated dies have complementally tapered surfaces for wedging said marginal portions together when said second. die assemblages is moved a sufficient distance toward said first die assemblage to initiate a heat sealing operation.

13. The heat sealing apparatus of claim 17 including:

(a) power means for moving said basket member in the direction of said pressure pad to overcome the action of said second-mentioned biasing means.

19. The heat sealing apparatus of claim 18 including:

(a) means for actuating said first power means to retract said second assemblage Iaway from 'said rst assemblage;

(b) means on said second assemblage for engaging said marginal `portions as said second assemblage is retracted, and

(c) means for effecting a disengagement of said lastmentioned means after a predetermined amount of retraction has been achieved.

(References on following page) 13 14 References Cited by the Examiner 3,060,652 10/ 1962 Eckman 53-42 X Zebal'th et al X 1(1); {ffm/ l S25- 31g FRANK E. BAILEY, Primary Examiner. eml 5 TRAVIS s. MCGEHEE, Examiner.

3,017,729 1/1962 Cheeley 53-184 X

Claims

1. A HEAT SEALING APPARATUS FOR PACKAGING PRODUCTS IN LIDDED CONTAINERS FABRICATED OF THERMOPLASTIC MATERIAL, SAID APPARATUS COMPRISING, (A) A FIXED SUPPORT, (B) A LOWER DIE ASSEMBLAGE CARRIED BY SAID FIXED SUPPORT AND ADAPTED TO RECEIVE A CONTAINER WITH ITS CONTENTS, (C) AN UPPER DIE ASSEMBLAGE MOUNTED OVER SAID LOWER DIE ASSEMBLAGE AND CONVERGENTLY MOVABLE THERETOWARD, (D) SAID UPPER DIE ASSEMBLAGE HAVING A PORTION ADAPTED TO RECEIVE A LID FOR SAID CONTAINER AND TO PRESS THEREAGAINST DURING CONVERGENT MOVEMENT OF SAID UPPER AND LOWER DIE ASSEMBLAGES, (E) A HEATED DIE ON SAID LOWER DIE ASSEMBLAGE HAVING AN OUTWARDLY FACING SURFACE ADAPTED TO SURROUND SAID CONTAINER AND TO CONTACT THE PERIPHERAL MARGIN OF SAID CONTAINER, (F) A HEATED DIE ON SAID UPPER DIE ASSEMBLAGE HAVING AN INWARDLY FACING SURFACE ADAPTED TO SURROUND SAID LID AND TO CONTACT THE PERIPHERAL MARGIN OF SAID LID, AND (G) POWER MEANS URGING SAID UPPER AND LOWER DIE ASSEMBLAGES CONVERGENTLY FIRST TO PRESS TO SAID LID AGAINST ITS CONTENTS WHEREBY TO EXPEL AIR FROM THE CONTAINER, THEN TO PRESS THE RESPECTIVE OUTWARDLY AND INWARDLY FACING SURFACES TOGETHER AND THEREBY TO HEAT SEAL THE RESPECTIVE PERIPHERAL MARGINS OF THE LID AND CONTAINER.