DE3151464A1 - Method and device for producing a tightly-sealed package - Google Patents

Description

SUBMITTED

Method and device for producing a tightly sealed pack

The invention relates to a method and an apparatus for producing a tightly closed Packing, in particular by making layers of a film material (which in turn are bonded multilayer films can be) welded to seal a pack tightly. Such a pack can, for example, be a Be vacuum pack, but can also contain an inert gas that helps preserve the contents of the pack, especially ^ if this is perishable.

Various methods for sealing films are known. Are currently widespread Applied: Clamping the neck of a bag made of the film material, heat sealing by simultaneous Applying heat and pressure so that two. Foil layers are welded together; and taping for example by one or both of the to be glued together Surfaces are coated with an adhesive so that the surfaces that come into contact close tightly, when they are pressed together.

In addition to heat sealing by pressing together It is known from US Pat. Nos. 3,989,778 and 4,069,080 to irradiate foils clamped together with laser energy in order to produce a

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localized welding of those in contact with one another to promote existing areas. It is also known from US Patents 3 ^ 77! 9 ^ and 3 247 04l, compressed To irradiate foils with infrared radiation from a nearby source for the purpose of bonding.

These older documents all relate to the application of heat to sections of film that are already there are in the relative position for sealing so that the application of such a system requires careful alignment of the clamped together film sections with respect to the emission path of the energy from the infrared source or the Laser j requires. Furthermore, it is especially when using IR radiation difficult, the presence of gaps between the infrared source (s) and the clamped film sections to avoid which (in order to have enough space for the handling of the packaged goods and the material surrounding them to be provided) are so large that the radiation losses that are inversely proportional to the square of the distance from the heat source.

To overcome these disadvantages of these older systems that use radiant heat to seal plastic material, the invention provides a method for the production of a pack before> which one goods wrapped in a plastic film with corresponding oil sections which are brought into contact with each other to seal the package, the holding the corresponding film sections out of contact before sealing, heating them with infrared radiation and then each other brings into contact so that they weld together.

The invention also relates to a device for producing a pack with a carrier for goods and a cover made of plastic film, at least one infrared radiation source, which is arranged in such a way that it supports the corresponding film sections of such a sheath irradiated, which are kept out of contact during the operation of the infrared sources, and facilities,. which then the corresponding film sections

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contact each other to close the package.

The method and device according to the present invention are applied to different pack types, however, they are particularly suitable for vacuum packaging goods in a chamber.

A further object of the invention is therefore a Process for the production of a vacuum pack in which a product is wrapped in plastic film, the wrapped item arranged in a vacuum chamber, this evacuated to the To reduce pressure inside and outside the plastic film, and sealing corresponding portions of the foil envelope to form a vacuum pack, the step the sealing of the film sections, irradiating these corresponding film sections with infrared radiation and the bringing together of the heated film sections, so that they weld when touched. "

A fourth object of the invention consists in a device for producing a vacuum pack, which device comprises a vacuum chamber, a carrier located in the chamber for a filled plastic sack, devices for pressing the sack neck in the chamber, devices for inflating the bag located on the carrier, its Neck is closed by the locking devices, infrared radiators in the chamber _s which can be switched on for the purpose of irradiating the inflated neck of the sack in order to heat the inflated neck material, as well as devices for releasing gas from the inside of the sack so that the sack neck after heating the sack by means of the Infrared radiator loses its puffed shape and the neck material comes into mutual contact and thereby closes tightly, includes.

The invention also relates to a pack, either according to the above method or using one of the above devices was made.

For a better understanding of the invention, a description follows, by way of example only, with reference to FIG

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the drawing. Show it

Pig. 1 is a schematic side view of one form of a Vacuum chamber in which the method according to the invention can be carried out;

FIG. 2A shows a detail of the one installed in the chamber according to FIG Sealing mechanism in section; Figure 2B is an end view of the sealing mechanism

according to Fig. 2A;
3 shows a schematic plan view of another form of vacuum chamber in which the method according to the invention can be carried out;

4 shows a view similar to FIG. 3 of a further embodiment of a vacuum chamber in which the method according to the invention can be carried out; and
5 shows a circuit diagram of a simple form of a control device for the infrared radiators according to FIGS. 1 to 4..

Fig. 1 shows a vacuum chamber 1 with a lower part 2 and a lid 3 _S which close tightly along their edge 20 and form a tight housing in which two plastic bags 4 (in this case made of heat-shrinkable material), which enclose goods 21, evacuated and sealed.

Heat from shrinkage is supplied to each sack 4 by means of two fans 6 and 7 * which are driven by motors 8 and 9, and by means of circular heating elements 10 and 11, which are shown in side view in FIG The heating elements 10 and 11 shown in plan view are identical, circulate air, "supplied. The radially outwardly directed air flow from the centrifugal fan rotors passes the heating elements 10 and 11, is heated in the process and then passes over the bags U on a support grid 12 in the chamber. The Sacks absorb heat from the air and shrink in the desired

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measured as a function of the degree of orientation of the film in its manufacture.

The chamber also contains upper and lower heaters 13 and 14 with infrared _{heat-radiating rod lamps (37 and 38 in Pig. 2A) 3} which radiate heat onto the spaced polene sections of the neck area of the sacks k and heat the neck area to such an extent that the film layers automatically weld together when these film sections subsequently touch one another, for example when the chamber 1 is pressurized again.

The exact construction of these upper and lower heaters 13 and 14 will be explained with reference to the detailed illustrations described in Figs. 2A and 2B.

The opening area of each sack is by means of a resilient sack holder, the upper and lower Parts 33 and 35 (also shown in Figs. 2A and 2B), wedged so that air from inside the Sack 4 between the upper and lower heaters 13 and 14 and the upper and lower parts 33 and 35 escape cannot, however, flow back through the opening into the sack due to the resilient jamming of the sack can.

Various evacuation cycles can be used in the chamber of FIG. 1.

According to a first example, it is possible to heat shrinkage act on the sack 4. by turning the fan motors 8, 9 and the heaters 10 and 11 before the Turns on evacuation of chamber 1. This leads to the sack material shrinking. This heat shrinkage is the Air trapped between good 21 and bag 4 is pressurized, and the trapped air keeps the bag inflated at a distance from the relatively cold goods, while the tension builds up in the heat-shrinking sack 4.

The air trapped in the sack 4 is then released when its pressure exceeds that of the elastic strip 33, whereby the shrinkage stored in the bulging sack

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energy the sack material shrinks back to the good 21. The vacuum pump is then switched on and the evacuation of chamber 1 takes place. With a corresponding delay, the bent wire 48 is put under tension, so that it tears the sack neck and allows a further evacuation of the sack through the neck. The chamber 1 continues to be evacuated in order to suck off the remaining air from the interior of the sack 4 and to enable the sack to be sealed. Such a cycle is the one described with reference to FIGS. 2A and 2B and disclosed in any case in British Pat. An alternate duty cycle for those in Pig. The chamber shown in I provides that the evacuation of the chamber 1 begins simultaneously with the start-up of the heaters 10 and 11 and the fan motors 8 and 9 and that, as a result of the jamming of the bag opening in the flexible bag holding device, a delayed suction of air from the interior of the bag 4 takes place. As a result, the sack inflates away from the good 21 when the pressure in the chamber surrounding the sack 4 falls faster than the air pressure inside the sack 4. As soon as the sack has inflated to the desired extent (which can either be determined by a cycle control which is based on the fact that a group of similar objects, which have been packed in a similar film and have been subjected to evacuation of the chamber at a similar rate, take the same time to inflate; or by means of mechanical sensors that respond to the inflation of the Sacks 4 respond, can be determined), the evacuation of the chamber is terminated so that the inflated state of the sack is maintained during the circulation of the residual air in the chamber 1 by means of the fan rotors 6 and 7. This hot air circulation brings about a further heat transfer to the material of the sack 4, the shrinkage energy of which is released because the sack is still kept out of contact with the enclosed good 21. As soon as this heating of the bag 4 has reached a desired level, the evacuation takes place

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resumed and the sack neck is sealed as soon as the pressure inside is sufficiently low has (high vacuum). Such a method is described in the British PatoAnnio Mr. 8023465.

Other procedures are also possible, with for example, the evacuation and hot air circulation start at the same time and continue uninterrupted, until a sufficiently low residual pressure (high vacuum) is reached is what the bag is sealed on.

In any of the above forms of process flow, the chamber of FIG. 1 preferably contains those shown in FIG 2A and 2B, upper and lower heaters 13 and 13 shown

As shown in FIG. 2A, the resilient bag holding device 30 is supported on an upper support 31 _9, which forms part of the chamber cover 3, and a lower support 32 of the chamber lower part 2. When the cover 3 approaches the lower chamber part 2, the upper support 31 lowers towards the lower support 32 until they assume the position shown in FIG. 2A.

A resilient bag retaining strip 33 made of a suitable rubber-like material is on the upper support 31 attached and fastened to this by means of screws 34, the flexible strip 33 touches along its lower edge a support element 35 “held by the lower support This can also be a strip similar to the strip 33. Once the neck of a plastic bag on the support element 35 is arranged while the chamber lid 3 is raised, does the lowering of the chamber lid 3? whereby the upper and lower supports 31 and 32 in the position according to Fig. 2A arrive automatically that the neck of the sack is held on the support element 35, so that one in the sack Any excess pressure that occurs and exceeds a certain value can be released by moving the bar 33. A retraction of the sack neck to the left between bar 33 and support element 35 acts under spring pressure

SUBSEQUENT

Pins opposite, one of which (36) shown in Fig. 2A which press the neck of the sack firmly onto the support element 35.

The flexible strip 33 has an angle of inclination such that air with a sufficient excess pressure can escape from the inside of the sack at least in the area of the openings between adjacent pins 36.

The sealing of the sack neck, whereby only a minimal air space is created in the sack at the neck, is achieved by means of upper and lower heat sources 37 and 38 in the form of rod lamps, the infrared radiation with a wavelength radiate, which is optimally absorbed by the plastic mass of the bags 4 located in the chamber, causes.

The wavelength of the emitted by lamps 37 and 38 Light is advantageously chosen so that it has the wavelength most easily absorbed by the bag material matches. The wavelength in question is suitably in the range of 3 to 4 ^ m for most Plastic films, including multilayer films and laminates, e.g. heat shrinkable (i.e. oriented) three-layer laminates made of ethylene vinyl acetate, polyvinylidene chloride and irradiated ethylene vinyl acetate.

After briefly irradiating the neck area with the heat radiators 37 and 38, the Saek material has its own Softening point reached, so that the layers of the bag material when pressed together in the area of the opening and Weld the neck tightly.

Wire mesh 39 and 40, the upper and lower pairs, which can be pivoted about pins 4la, 42a Carrier plates 41 and 42 are held, prevent the Saek material from contacting the upper and lower heat sources 37 and 38 comes into contact. Each support plate 4-1, 4-2. Has a slot 4-1b, 4-2b, in which one at the associated end a vertically movable upper or lower clamping rod 4-5 or 4-6 attached driver 4-3 or 4-4- slides. the lower clamp rod 4-6 has a main part with thereon means helical compression springs 4-6b elastically mounted

te "r jaw" ή6a. on, whereby., It is ensured that the clamping ^jaw: 46a yields when the two push rods 45 and 46 come into contact.

The holding device 30 further comprises a bent wire 48, which is held by the support element 35 and in the Pig. 2A arrangement of the holding device touches the inflated sack neck. When a current pulse is passed through, the wire tears the sack neck so that the gas (mostly air) can escape from the inflated quay before sealing. The wire 48 may, for example, have a sawtooth shape or a sinusoidal wave shape.

When the upper clamp rod 45 lowers, slide their drivers 43 in the slots 4Ib downwards and cause the upper support plates 4l to be pivoted counterclockwise and the heat source 37 and her Wire mesh 39 to the right off the path · which goes downwards Pivot moving upper clamping rod 45.

The drivers 44 of the lower ones also act

Clamp rod, when this moves upwards, with the slots 42b of the lower support plates 42 together, so that this laterally pivoted v / ground and the lower heat source 38 and its wire mesh 40 from the area of the upward moving clamping rod "46. This allows the film material between the two clamping rods 45 and 46 is pinched. At the same time, a blade 47 provided on the main base of the lower clamping rod is positioned above the Resilient jaw 46a released as a result of the yielding of the compression springs 46b and can during the sealing Separate any excess sack material from the neck.

Fig. 2B shows the drive mechanism which the ' upper clamping rod 45 set in vertical movement.

As can be seen from Fig. 2B, the upper clamping rod 45 consists of two separate parts, which by means of a central bearing 49 on a vertical guide rope ft 50 are supported, which allows vertical sliding of the two parts of the upper clamping rod 45.

The two clamping rod parts are attached to the lower ends of pressure members 51, the upper ends of which

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on double bell crank components 52, 52 ', one of which, 52, in Fig. 2A can be seen, are articulated.

The left bell crank 52 has a fixed pivot pin 53 on one corner, a trunnion 5 ^ on another corner that holds him connects to the pressure member 51, and a further pivot pin 55 on the third corner connecting it to one end of a secondary drive rod 56. _. ■ '.

The other end of the secondary drive rod 56 is at 57 with a corresponding corner of the right double angle lever part 52 'connected, which counterparts 53' and 5 ^ 'to the corresponding has pivot pins 53 and 5 ^ described above.

A first drive rod 58 is between the piston rod 59 of a piston 6Ό and a further pivot pin 6 * 1 on the right Double angle lever component 52 'attached. Advance and retraction of the Piston rod 59 cause the angle lever components 52 to move, 52 'iis or counterclockwise and thus a raising or lowering of the clamping rods 1 * 5 "

A similar drive lever connection with drive piston is provided to open and close the main beam of the lower clamping rod ^ 6 to move downwards. ·

As can also be seen from FIG. 23, a protective strip 62 is screwed to the upper clamping rod ^ 5, which delimits a gap in which the blade kj can enter when the upper and lower clamping rods. lower clamping rod ^ 5 and h6 meet.

As will be described later, the holding devices work 2A and 2B during the cycle of the machine in several stages.

The mode of operation of the device shown in FIG. 1 when using sacks h made of a heat-shrinkable, ie oriented, foil material is described below:

A filled but unsealed sack k made of heat-shrinkable packaging film is placed in the vacuum chamber 1; the chamber lid 3 is lowered so that the chamber can be closed and sealed on your hand 20.

One form of heat shrinkable (ie, oriented) film used for the sack h can be a three layer laminate of ethylene vinyl acetate, polyvinylidene chloride, and irradiated ethylene vinyl acetate, as disclosed in US Pat. No. 3,781,253 and by VR Grace

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'& Co. sold under the brand name "Barrier bag" virch

As explained above, when the chamber lid 3 is lowered, the flexible strip 33 comes down against the sack neck and presses it firmly against the surface of the pressure element 35. In this stage, the upper and lower clamping rods 45 and HS are retracted, and the heat sources 37 and ...- 3-8 are in the positions shown in Fig. 2A. . ■

Heat of shrinkage is applied to the outside of the bag prior to substantial evacuation of the air from inside the chamber, and the application of heat causes the bag material to begin to shrink. The air trapped in the effectively sealed sack (held by the elastic strip 33) opposes the shrinkage and keeps the sack material inflated at a distance from the surface of the goods contained therein (eg a slice of fresh red meat). While the bag is held at a distance from the material _surface} heats the outside circulating around the inflated bag material of this hot air continues and completes the Warmsehrumpfungsvorgang, is retracted to the material surface through the sheet material. However, the sack material has been inflated long enough at a distance from the product surface so that a corresponding heat transfer could take place on the inflated film, which is not able to give off noticeable heat to the product 21, and that the film could be brought to its shrinking temperature, so that a very high proportion of the shrinkage energy can be obtained »

During this time, the heat sources 37 and 37 are either switched off or, more expediently, at a low level Activated heating stage, which does not allow them to heat the film material of the sack neck to such a high temperature, that a merging occurs.

If the; Saek opening: in · -. "The" · flexible holding device. is clamped, ensures jamming. the former with progressive heat action on the outside of the sack by convection, that a built-up inside the sack Excessive pressure difference by releasing gas (usually

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Air) from the interior of the sack 4 to such an extent that the sack material continues at a distance from the enclosed good 21 remains bloated, can be regulated. Because the bloating effect depends on factors that make up a certain group of goods 21 are common (e.g. 3rd surface temperature, amount of air contained in the goods and surface quality - e.g. stickiness - of the property), it can be useful to determine by observation when inflation is likely to occur and then to program the process in such a way that the evacuation of all products in a group at the same time. begins and by means of a suitable. Time switch switched will. Other controls can be used if desired.

Because the sack is still during the warmth level is resiliently held at its quay, a further leakage of air from the inside of the sack in the unlikely In the event of an excessive pressure difference along the sack material, the rest of the sack is back on the Surface of the good 21 shrinks, so that a substantially Wrinkle-free envelope of the goods 21 is achieved and the sack neck is still available for sealing, if''sich the clamping rods 45 and 46 approach each other - until they make contact reach.

At the end of the inflation phase, before the evacuation of the When the sack begins, the bent wire 48 is briefly put under tension so that it tears the sack neck and thereby traps it Gas is released.

The evacuation "of the chamber (and the now torn sack 4) continues until the desired negative pressure is reached is. At the end of the evacuation phase or just before the lamps 37, 38 are placed under maximum voltage, so that they generate radiant heat of the desired wavelength an optimal heat absorption through the film material and heat the perforated sack neck to welding temperature.

The pistons 60 are then activated causing the upper and lower clamp rods to move closer together 45 and 46, with the heat sources 37 and 38 at the same time

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the associated wire grids 39 and 40 are pivoted to the side.

Once the upper clamp rod 45 is in contact with the spring-loaded clamping jaw 46a has reached, the further advance of the piston 60 leads to the fact that the blade 47 the sack neck cuts through '- and separates excess material. The clamping elements 45 and 46 ensure that the neck is held along the blade 47 and the seal is effected. The opening area of the remains during this process Sack still between the flexible strip 33 and the pressure element. 35 clamped so that the sack still remains is held securely within the holding device 30.

When the upper and lower clamping rods 45 and 46 are withdrawn, the heat sources 37 and 38 and theirs arrive Wire mesh 39 or 40 back into their position shown in Fig. 2A. The evacuation of the chamber takes place after this withdrawal the clamping rods 45, 46 instead, so that remaining air can escape unhindered from the sack.

When the vacuum chamber is under pressure again when it is opened is set, the. heated neck parts of the sack left by the clamping rods 45 and 46 pressed together to a To achieve welding and to reduce the size of excess bag material in the vicinity of the visual welding zone and to give the finished pack a nice look.

The protruding sack material separated by the blade 47 is still between the flexible strip 33 and the .Anpreßelement 35 held, and can during or after removed after removing the pack from the opened chamber.

The method described above is particularly useful to be used for moist products, for example fresh red meat, in heat-shrinkable bags, as the pressure increases on the meat surface during puffing of the sack causes the moisture retained in the product tend to fog up the inner surface of the puffed up product Sack is avoided. It also allows the trapped air to escape quickly when perforating of the sack so that the sack material quickly encloses the goods,

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before such fogging occurs. The appearance of the finished pack is therefore in the case of moist products, like fresh red meat, particularly attractive.

At. all goods packed according to this procedure is the wrinkle-free shape of the end product through the use of a previous shrinkage stage with subsequent Evacuation (as opposed to the usual sequence of vacuum sealing and then shrinking) improved.

The finished pack according to the invention is also compared to the packs produced in a known manner by shrinking, using a water-shrink bath, the temperature drop effects of the relatively cold product, which has a high heat capacity, significantly improved, since the shrinkage of the film in contact with air a better '. utilization of the greater increase in thickness allowed, with the result that the Sack tightness properties (important for a hermetic Completion of the product and fresh? until the time of consumption) are more effective. Furthermore is the resistance of such a sack is better because of the greater thickness.

Because the air trapped inside the bag during preheating and shrinking causes a collapse prevents the sack and delays the contact of the sack with the cold goods, this increase in thickness is even more noticeable, as well as the wrinkle-free appearance of the sack, that again the extent to which the latent shrinkage energy is utilized depends on the film material. There is shrinkage due to air currents which move around the entire product, the sack also shrinks evenly around the product and this switches off the risk of entrapping air bubbles behind the "equator" of the product (i.e. the area of the largest cross-section in a transverse plane to the longitudinal axis of the sack).

The property mentioned above that x \ renig or no water vapor in the air between good and shrinking

Sack is located (due to the beginning of the shrinking process before a pressure decrease, which even causes a slight increase in pressure entry), guaranteed,

that less heat of shrinkage is required because the dry Air on the inside of the sack absorbs less heat than moist air.

Since the upper and lower beams 31 and 32 of the resilient Holding device 30 on the lower chamber part 2 or the Chamber lid 3 are supported, they automatically approach to touch when the chamber is closed, and all the operator has to do is towards it make sure that the neck of the sack 4 is on the pressure element rests before the chamber closes.

If the filled bags are brought into chamber i by means of a conveyor system, if desired, the conveyor system can ensure that the Saekhals, when the bag H is stopped, is correctly aligned for the purpose of clamping without an operator having to carry out an alignment.

As stated above, other devices for closing the bag can be used in conjunction with the heat-sealing emitters 13 and 14, _{or the like}

For example, the Saekhals can use a conventional sealing bar 70 (Figo 3), which both cuts off protruding material and seals the bag opening along the pressure line between the upper and lower iClemming bar (by means of a resistance heater)? "The application of heat to the neck area between the sealing bar 70 and the good 21 leads to the sack material in the neck area being heated to such an extent that it is when the chamber 1 is pressurized again _? self-welded when it collapses 5 so that the pack has a much tidier neck area "

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The sack neck can also be introduced into a crimping device 71 (FIG. 4), so that it is in a Vacuum chamber is puckered when it closes, and a clasp can be attached to the neck of the sack by means of a suitable Device 71a can be attached after the end of evacuation and shrinkage. One in the chamber working device for attaching "clasps" is for example in GB-PS 1,353,157.

Another possibility is that the device 71a for attaching clasps according to Hg is omitted and that the crimping is carried out after the sack neck in the area to be crimped through the switched on infrared heater has been heated · When the so heated and softened areas of the sack neck by the curling device 71 (which may, for example, be of the genus described in GB-PS 1 353 157, 1 361 142 and 1 496 740) are contracted the curling effect is sufficient that the neck material sticks together and the appearance of a wedged neck, but without a clasp, assumes. The mere softening of the neck area of the sack by the action of heat sufficient to bring about an intimate contact and a sealing of the curled neck region ..

The crimping device 71 shown schematically can work, for example, in two stages, as in FIG GB-PS 1,353,157 disclosed by putting the sack first summarized in a horizontal slit-like shape, when the chamber closes and there is sufficient resistance to the outflow of gas from the inside of the sack, so that the desired inflation effect before switching on the infrared heater is supported. In the second stage of the Crimping is reduced the length of the slit and the sack neck in a self-adhesive, crimped Bundled shape. The bag opening ″ can, however, also be kept closed in other ways, as can the crimping device 71 can then be actuated and the

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Sack neck after heating for the purpose of: Completely curling the inflation.

The above description of various possible process sequences with the chamber 1 according to FIG. 1 relates consistently on the use of a heat-shrinkable film. The method according to the invention can also be applied to other films, for example self-sealing films which are softened under the action of heat and then welded when they come into contact with each other.

The alternatives shown in FIGS. 3 and 4 can also be used Chamber constructions - on any suitable film, including heat shrinkable and self-amalgamating Foils, can be used.

Fig. 5 shows a schematic representation of a possible control circuit for switching the radiant heater 37 and 38. A variable transformer 72 is inserted between inputs 73 and 74, and the same inputs 73 and 74 are through a shunt line, the one Microswitch 75 and a timer 76 contains connected. Another shunt line contains a switch 77 and a breaker 78, which in turn is connected to switching contacts 79 and 80 in the secondary circuit of the variable transformer 72. The two S. switching contacts 79 and 80 control the excitation of the infrared radiators 37 and 38, which run parallel in the secondary circuit of the variable transformer 72 are switched on.

The variable transformer is constantly energized, and the start of the cycle is activated by actuating the microswitch 75 initiated on a moving mechanical part, for example the closing of the chamber lid 3? appeals to. With the closing of the microswitch 75 begins the control cycle of the timer 76, so that the switch 77 closes immediately and the breaker 78 energizes j which closes the contacts 79 and 80 and puts the radiators 37 and 38 under voltage.

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After a fixed by the timer 76

time delay, the switch 77 is opened, the Circuit to breaker 78 interrupted, the contacts 79 and 80 opens and the radiators 37 and 38 switch off.

In a particularly useful modification of the circuit according to FIG. 5, precautions have been taken to ensure that the radiators 37 and 38 are on. at a reduced standby voltage (e.g., 20% of its full voltage) and not completely turned off when the breaker 78 is not energized. This can be achieved, for example, in that a two-way switching system is provided on the contacts 79 and 80, so that a standby circuit is connected in one position of the contacts, which supplies the radiators 37 and 38 with their standby voltage, and in the other position of the contacts the main circuit shown in Fig. 5 is closed. ■ "-.-.

By adjusting the variable transformer 72, the voltage supplied to the radiators can be varied and the timer 76 can also be regulated, so that a dead time of e.g. 2 to 6 seconds for the operation of the emitters 37 and 38 is possible.

Preferably used as emitters 37 and 38 are Philips lamps of the type 13195 2/98, produced by the Philips Electrical Company.

The advantages of using the weld sealing system described and illustrated here are, among other things, that the thermal inertia the IR emitters 37 and 38 is very low, so it it is possible to switch it on only when welding heat is required. Sealing by fusing also has the advantage that there is no physical contact between the radiators supplying the heat and the plastic material to be connected takes place *

It is a particularly important advantage of the invention that the heat is supplied to the foils by radiation before they are brought into contact with one another and 38 must be placed close together. Instead, the lamps can be quite far apart, and the sack neck material can be inflated near the lamps to reduce the distance from the heating source to the sack material · This: · makes a lot simpler device in terms of (a) the introduction of the sack into the chamber or (b) _s more generally (when the melt sealing of a film envelope is carried out to form a package with or without the use of a vacuum chamber), the arrangement of any two film parts to be welded in one for heating to the melting temperature with the position suitable for the device according to the invention.

Furthermore, the amount of energy supplied to the films can be changed quickly and easily either by changing the supplied to the lamps. Voltage or by changing their duty cycle or by regulating both Parameters are controlled ο

If desired, the Ealsregion of the sack can be printed with a material that has a high absorption coefficient in order to achieve an even more intensive localized heat absorption _{or the like}

The envisaged negative pressures for the above described process are from about 6.665 mbar (5 Torr) but "If desired, much milder negative pressure (higher residual pressure) are applied (for example, when products such as so-called high gas-end cheese which naturally gas, _P B _o carbon dioxide, deliver and do so to a much greater extent when they are present at high vacuum packaged _s).

In Figs. 1, 3 and 4- the devices comprise the Apply heat to the sack material, blowers that circulate the hot air. However, other heating devices can also be used can be used for the sack together with the radiant heat emitting heaters 13 and 14.

Temperatures of 90 to 140 ^° C. are required for the puffed film in order to achieve heat shrinkage in the case of a biaxially oriented shrinkable film. The radiant heaters 13 and 14 can, however, heat the neck area of the film to higher temperatures in order to promote the melt sealing.

The above description relates generally to the treatment of a single sack 4 in the chamber, although it is very clear that in Fig. 1 two separate bags 4 are provided. The inventive The method and apparatus can be applied to one pack or two or more at the same time sealing packs, and this versatility applies equally to the three various embodiments shown in FIGS. 1, 3 and 4 as well as to all other execution requirements falling within the scope claimed.

Claims (1)

51464 Bern TcL:. ^ Ιί 1 1. ΟΞί. 1931 NachGEREJCf-JT patent claims: 1. Process for the production of a package, in which goods (21) are wrapped in a plastic film (4) envelops, which has corresponding polishing sections, which can be brought into contact with one another in order to heat-seal the package, characterized in that the corresponding. .. Keeps film sections out of contact before sealing, corresponding to those kept out of contact Heated foil sections by means of infrared radiation and the heated foil sections then come into contact with one another, so that they melt together when touched. 2 _a method according to claim 1, characterized in that the plastic film has the shape of a sack (4) 9 the neck of which forms the film sections to be sealed = 3rd method according to claim 1, characterized in that the heat sealing is carried out in a vacuum chamber (2, 3) in which the wrapped material is located, and that the chamber is evacuated in order to reduce the pressure inside and outside the plastic film (4) to be reduced before the corresponding sections of the film envelope are sealed to form a vacuum pack _o 4-c method according to claim 3 _5, characterized in that the plastic film has the shape of a sack (4) ₉ whose neck is clamped shut in order to delay the escape of gas from the sack interior (4), and which is inflated ₉ and that the Infrared radiation is emitted from sources (13, 14) which are arranged near the neck of the sack, around the delayed by the NAOHeRICH Gas leakage from the inside of the bag to inflated neck heat, and that the gas is then allowed to escape from the heated bag (4) and the neck portions together are brought into contact so that they are sealed to the touch. 5 · The method according to claim 4, characterized in net that the gas escapes from the bag (4) is made by resiliently pinching the neck of the sack to prevent gas from escaping. prevent up the pressure difference between the inside of the sack and the surroundings of the sack reaches a value at which the the sack neck retaining device (30) yields and allows an outflow through the sack opening. 6. The method according to claim 4 or 5, characterized in that that the sack neck is inflated by the sack material with additional heating devices (6, 7 »8, 9, 10, 11) heated, and that the escape of Gas is caused from the inside of the sack by tearing the inflated sack neck, so that a substantially unhindered escape of gas from the inside of the bag is possible. 7- method according to claim 6, characterized in that that the additional heating devices comprise reinforced convection heaters (6, 8, 10) and (7, 9, 11), circulate the hot air on the outside of the sack (4). 8. The method according to claim 6 or 7 _5, characterized in that the Ifolienmaterial is a heat-shrinkable film. 9. The method according to one of claims 4 to 8, characterized in that the inflation of the sack (4) is effected by heat shrinking the sack material while the sack neck is held clamped shut. 10. The method according to claim 4 or 5 »thereby characterized in that the sack is inflated by evacuating the chamber (2, 3) so that a pressure difference due to the clamped sack neck NAC-JGHREtOHT builds up on the film material of the sack. 11. The method according to any one of claims 1 to 10, characterized in that the film material is a multilayer Film is at least one ethylene-vinyl acetate layer, a layer of polyvinylidene chloride and a layer of irradiated ethylene-vinyl acetate-comprises, and that the wavelength of infrared radiation is 3 to 4- / tty amounts to. 12. Device for producing a pack, with a carrier (5) for goods and a plastic film surrounding it, a heat source for heating corresponding parts of the plastic casing and devices which bring the corresponding parts of the plastic casing into contact with one another in order to close the pack, characterized in that the heat source at least comprises an infrared radiation source (13, 14 ·) which is arranged so that it irradiates the corresponding foil portions a _r supported plastic sheath, and in that means (8, 10) and (9 ₅ 11) are provided, which keep the corresponding foil sections out of mutual contact during the activity of the infrared radiation sources. 13 »Device according to claim 12, characterized in that the infrared radiation source (13-14) and the carrier (5) are arranged in a vacuum chamber (2, 3), that the device that keeps the corresponding film sections out of mutual contact, devices ( 30) which clamp the neck of the sack (4) in the chamber, as well as devices (6, 8, 10) and (7, 9 ₅ 11) for inflating the neck of the sack supported on the carrier (5), its neck is clamped shut by the clamping device, and that the devices which bring the corresponding film sections into contact with one another to close the pack, devices (4-8) for releasing gas from the * "'I NACf-SQHRHlCHT I Cover the inside of the sack (4) so that the sack collapses from its inflated state after heating by means of the infrared radiator (13 » 1 * 1), so that the heated neck material comes into mutual contact and is thereby sealed. 14. The device according to claim 13 *, characterized in that that the means for retaining the neck comprises a unit (71) which constricts the sack neck, the able to close the sack neck by crimping, the sealing taking place. 15. The device according to claim 14, characterized in that the crimping unit (71) is controlled so that it contracts the sack neck after energizing the infrared radiators (13, 14). 16. The apparatus according to claim 14, characterized in that a device (71 a) for attaching Clasp is provided which attaches a locking clasp to the neck of the sack after the inflated sack neck has collapsed. 17. Device according to one of claims 13 to 16, characterized in that the devices that the Cause collapse of the inflated sack neck, an element (48) for tearing the inflated sack neck exhibit. 18. Apparatus according to claim 17, characterized in that the devices which cause the collapse effect of the inflated sack neck, cooperating holding jaws (45j 46a), which in the vicinity of the the sack-tearing element (48) on the side thereof facing the carrier (5) are arranged and which pinch the sack neck ^ around it after it emerges of gas to close again through the torn neck portion. 19. Device according to one of claims 13 to 18 _S, characterized in that the infrared radiator SUBSEQUENTLY comprise a pair of flashlights (13 * 14) parallel to each other are attached on both sides of the point where the inflated neck material of the sack (4) has its place. 20. The device according to claim 19 * characterized j that the devices clamping the neck are a pair of parallel clamping rods (33 ·> 35), which are arranged near the gap between the rod lamps (13 * 1 * 0 are and the neck of the sack (4) between each other pinch. 21 ο Device according to Claim 2O _5, characterized in that at least one (33) of the clamping rods has a resilient clamping effect so that gas can escape from the inside of the sack if an excessive pressure difference builds up on the polishing material of the sack. 22. The device according to claim 18 and one of claims 19 to 21, characterized in that the Holding jaws (45, 46a) can be reciprocated to and fro along a working section and that the rod lamps (13 * 14) can be swiveled between a working position, in which they are in the working section between the spaced holding jaws (45, 46a), and a rest position in which you have left this working section, so that the holding jaws are can approach each other, are appropriate. 23 Device according to Claim 22, characterized in that that the flashlights · screens (39 * 40) are assigned, which a physical contact of the flashlights (13s 14) with the inflated sack neck material during heating. 24. Device according to one of claims 19 to 23, characterized in that the rod lamps (1.5, 14) Have reflectors, the entire radiation of each rod from lamp (13 or «. 14) in the space between the align both flashlights. 25 »Device according to claim 24, characterized in that that each reflector consists of a reflective NAOHGEAR? CALIBRATED There is a coating on a surface portion of the lamp (13 or Ik) , which coating reflects radiation which would not naturally be directed into the space between the lamp (13 and Ik) . 26. Device according to one of claims 19 to 25 *, characterized in that they have devices for supplying energy to the rod lamps (13j Ik) at a first height at which they emit infrared radiation with an intensity sufficient to heat the inflated sack neck, and at a second level at which they work in standby mode with significantly reduced power consumption. 27 · Device according to one of the claims. 1 $ to 26, characterized in that it has a time switch (75) for controlling the duration of the emission of infrared radiation from the flashlights (13, 14) as well as devices (72) for regulating the radiation for heating the sack. 28. Device according to one of claims 13 to 27, characterized in that the device for inflating the sack neck at least one air circulation fan (6, 8) and (7, 9) in the chamber and a heater (10, 11) for Has heating the circulated air. 29. Device according to one of claims 13 to 28, characterized in that it has a device (^ 7) for separating protruding sack neck material from the pack after actuation of the infrared radiator (13, Ik) . 30. Pack produced by the method according to one of claims 1 to 11 or using the Device according to one of Claims 12 to 29.