CS201530B2 - Mechanism for the tigth joining the covers from thermoplastic material - Google Patents

Abstract

1515145 Seaming non-metallic sheet material GD SpA 4 July 1975 [10 July 1974] 28380/75 Heading B5K A heat sealing device, positioned adjacent a sealing station of an intermittently-rotatable wrapping wheel 1, comprises a reciprocable member 7 having a narrow heat sealing face, a heat source 10 adjacent the sealing face, and a probe 11 for measuring the temperature prevailing at the sealing face and responding thereto to control the heat sealing time of the device. The wrapping wheel 1 on which a packet P of cigarettes is wrapped in an outer thermoplastic sheet S is intermittently rotatable through 60 degree angles around a shaft 2 and comprises six radial compartments 3. At a station I, a packet P together with a sheet S is inserted into the compartment 3 thereat so that two ends of the sheet S protrude, these ends then being folded on to the external side of the packet P by a movable member 4 and an edge of a fixed guide 5. The folded ends are heat sealed at stations II, III through breaks in the guide 5 by members 7, 71 mounted on supports 8, 8<SP>1</SP> oscillatable about shafts 9, 91. An electrical resistor 10, 10<SP>1</SP> and a temperature measuring probe 11, 11<SP>1</SP> are inserted in the body of each member 7, 7<SP>1</SP>. The parts of the wrap adjacent the sealing area are protected from irradiated heat by thermally insulating plates 12, 12<SP>1</SP>, fixed to the guide 5. Each packet P is ejected by a pusher 6 into a channel 13, Fig. 2, in which the packet ends are sealed by reciprocable members 14, 14<SP>1</SP> mounted on supports 15, 15<SP>1</SP> and provided with heat sources 10, 10<SP>1</SP> and temperature measuring probes 11, 11<SP>1</SP>. The members 14, 141 act on the packet ends through slits in thermally insulating plates 16, 16<SP>1</SP>.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for tightly sealing packages of thermoplastic material in packaging machines, in particular on machines in which the packaged articles move in succession on an intermittently moving packaging line at variable speeds and where they are. repackaged in a thermoplastic foil top cover. In particular, it relates to a device for tightly sealing the top packs of a pack of cigarettes.

Thermoplastic materials which in. Recently, they have found widespread use in the repackaging of an airtight topsheet, and which are used in place of the previously conventional cellophane due to the low cost and lower thickness, have the disadvantage that the temperature range to which they may be exposed during thermal bonding is relatively narrow . Above the upper limit of the acceptable temperature range, there is considerable shrinkage of the film, which results in aesthetically defective folds on the package, which can also cause the package to tear. While cellophane only melts the waterproof outer lacquer layers and not the inner viscose backing layer itself, the material is exposed to its full thickness when thermoplastic foil is thermally bonded. It is therefore clear that the wrinkling of the foils in. due to shrinkage. Yippee, . with excessive heating of the bonded surfaces much more noticeable in modern thermoplastic films. than cellophane. Disorders of this. They occur in areas of direct heat application, and in adjacent areas take the form of corrugations and folds due to the shrinkage of the packaging. material.

In order to avoid these drawbacks, devices for sealing the thermoplastic packages are provided. so that. the action of the coupling devices is located on a minimum area which is still sufficient to secure it. sufficient connection. The joining is carried out in the rest positions of the packaged articles, moving in an intermittent motion along the production line through the joining. habitat.

In the case of packaging lines operating at high speeds, problems arise due to the difficulty of the known coupling devices. precisely reach the required temperature levels within the desired range. Known sealing means for sealing the packages are neither equipped with temperature detecting elements at the connection point nor adapted to this temperature. could be controlled. Therefore, there may be insufficient heating of the. as a result too. short delays at the junction, or vice versa, to overheat the junction point by excessive heat input or too long dwell time at the junction. If the heat input is matched with a certain speed of movement of the package between the stations and its residence time, this does not in any way address the adaptability of the coupling device to the varying speeds of the packaging line. This variability is common in high speed packaging lines in practice and the use of known devices for tightly sealing packages of thermoplastic materials raises difficult problems.

This drawback eliminates the device for tightly sealing the packages of thermoplastic material, especially on machines which wrap successive packs of cigarettes after intermittently moving the packaging line at variable speeds, at individual stations of the line, at least one of which has a device for tight. joining the packages, the device being coupled to the carrier reciprocating towards the package whose package is to be tightly closed and back therefrom, while coordinating the movement of the carrier with the intermittent movement. and comprising a connecting body comprising a heat source supplied from the supply circuit and having a connecting end directed towards the packaging line according to the invention, characterized in that the connecting body is provided with at least one temperature sensing probe. a sealing end connected to a thermostatic temperature regulator that is incorporated into the supply circuit of the heat source of the connecting end.

According to a preferred feature of the invention, the connecting body has a wedge shape and the connecting end is formed by the apex of the wedge, the heat source being placed in a cavity formed in the connecting body at the connecting end.

Due to the presence of a temperature sensing probe connected to the heat source control circuit of the coupling body, which can be set to a precisely predetermined temperature, accurate temperature adherence to the joint region can be achieved. Thus, the wrapping machine can operate at different speeds as desired, without adversely affecting the operation of the coupling device, since in the region. An accurate, predetermined temperature will be maintained due to the presence of a thermostatically controlled supply circuit of the heat source. Thus, if the temperature controller of the coupling body is properly adjusted, there will be neither insufficient heating of the joint nor overheating of the thermoplastic film, which would lead to defects on the finished package.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained in more detail below with reference to the accompanying drawing in which: FIG. 1 is a cross-sectional view of a circularly arranged wrapping line provided with a device according to the invention; provided with the coupling device according to the invention.

FIG. 1 shows a rotary carrier 1 which rotates clockwise intermittently around the horizontal shaft 2. The rotary carrier 1 has six radial compartments 3, which in turn rotate about the shaft 2 through the receiving station I on which it is the cigarette pack P with its narrow side side first, together with the sheet S of the thermoplastic overwrap foil, is inserted into them from the previous part of the packaging line. Both ends of the film sheet S, which at the moment of insertion into the compartment 3 at the receiving station 1 project radially over the circumference of the carrier 1, are bent on the outer side surface of the package. 5, which follows the arc path of the edge of the rotating compartment 3 of the carrier 1.

At the second and third stations II and III, where the segment 5 is interrupted, there are devices for sealing the containers according to the invention. The packing tightness ties are each connected to a respective carrier 8 reciprocating in a radial direction to and from the package · P at the respective stations II and III, by matching the movement of the carrier 8 with the movement of the compartment 3 with the package P after the changing line. As can be seen from the figure, the carriers 8 are mounted on shafts 9 parallel to the shaft 2, around which they oscillate.

The device for sealing the package itself consists of a wedge-shaped connecting body 7, the apex of which forms the connecting end 17 facing the rotating carrier 1. The connecting body 7, 7 'is additionally provided with a heat source 10 inserted in the cavity 14 near The heat source 10 is made, for example, from an electrical resistance. The coupling body 7 is further provided with a probe 11 for sensing the temperature of the coupling end 17, which is inserted into a corresponding recess in the coupling body 7. As shown schematically in FIG. 1, the probe 11 is connected to a thermostatic temperature controller 18 which is incorporated to the supply circuit 15 of the heat source 10. Thus, the desired heating temperature of the connection area can be set in advance and this temperature is automatically monitored as a result of said arrangement.

In addition to this arrangement, the package is protected from the effects of heat radiated from the connector body 7 by a cover 12 of thermal insulation material secured to a segment 5 that overlaps the outer side surface of the package P up to the area on which the connector body 7 operates.

Giant. 2 shows a second example of the use of the device according to the invention, in which, instead of a circular movement, the package P is moved along the length of the conveying channel 13. The device according to the invention is formed as connecting elements 7 working on both sides of the package. Also in other details, the device for sealing the packaging of Fig. 2 is designed in the same way as in Fig. 1.

P outside the abutment region of the connecting end 17 is provided by the cover plates 16. In the present example, these covers 16 are shown as stationary plates with a gap for insertion of the connecting end 17, but they can also be movably adjusted so that cover the area of the foil wrapper outside the actual area of the fusion joint.

Claims (2)

the subject of the invention A device for tightly sealing packages of thermoplastic material, in particular on machines which wrap packets of cigarettes in succession on an intermittently moving packaging line at varying speeds, at individual stations of the line, at least one of which is located. for sealingly sealing the packages, the device being coupled to a carrier reciprocating towards the package whose package is to be tightly closed, and back therefrom, by aligning the movement of the carrier with the intermittent movement of the package along the packaging line, and formed by a coupling body comprising a heat source supplied from the supply circuit and with a coupling end oriented towards the packaging line, characterized in that the coupling body (7) is provided with at least one probe (11) for sensing the temperature of the coupling end (17); connected to a thermostatic temperature regulator (18) which is at patterned into the power supply circuit (15), source (10) heat the connector body (7). Machine according to claim 1, characterized in that the connecting body (7) has a wedge shape and the connecting end (17) is formed by the top of the wedge, the heat source (10) being placed in a cavity (14) formed in the connecting body (7). ) at the connecting end (17).