FR2520707A1 - Automatic joining of plastics sheets for packager - allowing continuous pack prodn. while rolls of sheet are changed - Google Patents

Abstract

Appts. for automatically joining sheets of plastics material feeding a packaging machine consists of a mechanical means of advancing the sheet, an electropneumatic device for positioning the two ends to be joined, a seamer, and a system for detecting the end of a sheet. Two rolls of the material are provided, one in use and one waiting, the beginning of each new roll being joined to the end of the old one and the empty one replaced. Used esp. in the mfr. of blister packs for pharmaceuticals, etc. Down-time is eliminated and labour and waste of packaging and contents reduced.

Description

 The present invention relates to an automatic welding device for plastic sheets on packaging machines, which can be used, inter alia, for packaging drugs in solid form.

 In general, the packaging of consumer goods as well as drugs in solid form (tablets, capsules, dragees,.) Is commonly carried out using plastic sheets, formed into cells and often glued or welded against a sheet. aluminum, which allows their individual release easily by local tearing or peeling of the aluminum foil. In all these cases, the packaging is carried out by an automatic packaging machine, fed with a sheet of plastic material (generally polyvinyl chloride in the form of rolls.

 However, when the plastic sheet roll comes to an end, it is necessary that a technician monitors the machine, whether there is an alarm and an automatic stop or not, and replenishes the machine with a new roll and connects sheets. This operation is carried out, after the machine has stopped, as follows: the technician places a new roll, unrolls a sufficient portion of the sheet from the new roll to attach it to the portion of sheets remaining on the chain by means of bands adhesive, cut the common portion at an angle and glue the two well-fitting portions together with an adhesive tape or a welding machine; then he restarts the machine while carefully monitoring the correct introduction and progress of the new sheet and he must have the platelets of packaged product corresponding to the portion of glued sheets specially removed, because this portion. has a highly defective appearance.

Some times it is even necessary for him to repeat the operation because an offset of a few millimeters of the plastic sheet is enough to block the machine.

 As this roll changing operation requires nearly 10 minutes on average per roll, the scrolling of which takes about an hour for a drug packaging machine, this results in a loss of up to 15% of the production potential. In addition, defective product platelets also constitute a significant loss when the product itself is very expensive, which is often the case with drugs.

 We have now found an automatic welding device, usable on packaging machines, a device which allows the continuous movement of the plastic sheet and thus considerably improves the efficiency of the machine, while eliminating part of the handling and the waste. due to the connection of plastic sheets.

 The device according to the invention comprises (A) a mechanical component for advancing the sheet, (B) an electropneumatic component, (C) a welding component and a detection system (D) for the end of the roll. Where appropriate, it also includes (E) a coordination system.

 A device according to the invention is shown diagrammatically in the appended figure. The mechanical advance component (A) of the plastic sheet is -adapted to the packaging machine. Such a machine usually comprises a system I for pulling the plastic sheet 2 by jerking, by pinching the sheet, which subsequently makes it possible to cut a precise quantity and a precise format of inserts , forming them into cells and filling them with the consumer product. It can also include a complementary entrainment system 3 synchronized with the traction system 1 and intended to regularize the course of the sheet. Finally, it includes the roll 4 of plastic sheet engaged and a spare roll 5 waiting on its support. According to the invention, a reserve of sheet 6 is added to the traction component used to feed the chain during the operation. roll change when welding.

 The reserve 6 can be constituted by a deflection of the sheet by means of a pulley retained by a mechanical spring system 7, electromagnetic but preferably with compressed air, which makes it possible to connect it to the electropneumatic system (B).

 In order not to overload the drawing, the pulleys and the transmission and guide rails of the sheet are not all shown and are not numbered.

 The electropneumatic component (B) essentially comprises the double-acting locking cylinders 8 and 9, making it possible to alternately block the sheet of the waiting roll (5 in the figure), or else simultaneously the sheets of the two rolls during the welding operation .

It also controls the approximation of the welding jaws (C) and advantageously the unlocking of the reserve 6 when the spring 7 is replaced by a compressed air cylinder. In the case where the rollers used are such that the sheet does not separate from the coil, it is possible to add an end-of-coil cutting system to the electropneumatic component (B).

 The welding component (C) is constituted by an apparatus for welding plastics by high frequency commercially, the jaws of which are adapted to the width of the sheet (only the jaws are shown diagrammatically in the appended figure). Such an apparatus makes it possible to weld the plastic sheet in a short period of time (of the order of 1.5 seconds, including cooling).

 The end of roll detection system (D) comprises for example two electrical spring contactors 10 and 11 in which the electrical contact is made when the sheet of plastic material (serving as insulation) has passed. The electrical signal thus produced is used, if necessary after a delay corresponding to the scrolling of the end of the sheet from (D) to (C) and for the time necessary for welding, to trigger the entire electropneumatic system (B) , stopping the drive system 3 and activating the welding system (C). Finally, it usefully includes a back-and-forth device between the contactors 10 and 11 on the one hand and the control of the two jacks 8 and 9 on the other hand, that is to say that each time only the contactor corresponding to the roller at work is in service and the function of cylinders 8 and 9 is reversed.

 It is obviously possible to use, instead of the electrical contactors, an optical detection system, for example small gas lasers whose beam is partially interrupted by the plastic sheet until the end of the coil and which are placed next to an electric photo detector.

 Finally, the entire detection system is advantageously coordinated by an analog or logic electonic device (E) (microprocessor) which makes it possible to synchronize the electropneumatic component (B), the welding component (C), the mechanical advance component. (A) and the end of roll detection system (D). This device is not shown in the appended figure.

 The following example, with reference to the appended figure, will make it easier to understand the operation of the device according to the invention.

EXAMPLE
A "UHLMANN UPS-3" thermoformer for pharmaceutical packaging is used, the draft (by the traction system 1) has been adjusted to 210 mm / s (+ 1 s.

return stop) for the production of blister packs containing medicines. In addition, an electropneumatic system ("BOSCH" equipment) is used which controls the jacks 7, 8, 9 and the welding jaws C and which is connected to the detection system D.

The welding device is an "ATHIMONNIER" equipment comprising a high frequency Iioo W power generator of type B4 / 1, an electrode of type K 20 and a preheating box for the electrode.

 The sheet 2 of plastics material engaged (polyvinyl chloride) comes from the roller 11, passes against the con.

electric tractor 10 in service, then by the pulley and the guide channel in front of the unlocked cylinder 8 and the welding jaws (C) open, by the driving roller 3, by the reserve 6 set at 300 mm (thus ensuring approximately 3 s of autonomy) and finally in the traction system 1 of the thermoforming machine.

 The spare roller 5 is installed on its support, the sheet is passed through the contactor 11 at rest and it is engaged in the jack 9 up to the welding jaws C and the jack 9 is blocked.

 When the roller 4 is unwound, the end of the sheet passing through the contactor 10 triggers, after a delay corresponding to a draw, simultaneously the electro-pneumatic control, the welding and the stopping of the driving roller 3. The electro-pneumatic control blocks the jack 8, unlocks the cylinder 7 for a period of 3 s. and brings the welding jaws C closer for 1.5 s., then successively spreads the jaws C and unlocks the jacks 8 and 9 while the drive roller 3 is restarted and the jack 7 is blocked again as soon as the reserve 6 is fulfilled.

 Thus the new roller 5 is in service and the supervisor of the machine can remove the empty roller 4 and replace it with another roller, the sheet of which he will successively introduce into 10, 8 and C.

 The sheet change and the welding carried out with the device according to the invention are not only rapid (the operation lasts approximately 3 s.) But the connection of the sheets is sufficiently regular so that at most a single row of unfilled blisters is to eliminate. In addition, the supervisor of the packaging machine does not need to monitor the end of the rollers and can change the rollers practically at any time, that is, he has almost the entire duration of a roll (about an hour).

 The device according to the invention finds its utility in all packaging machines of the thermoforming type and especially in the industry of valuable products such as pharmaceutical products.

Claims (6)

 1. Device for automatic welding of plastic sheets on packaging machines comprising a mechanical component for advancing the sheet formed by a traction system and if necessary by a complementary sheet drive system, a sheet roll engaged and a roller waiting on its support, device characterized in that a sheet reserve, an electropneumatic component, a welding component and an end of roller detection system are added to the mechanical advance component.  2. Device according to claim 1, characterized in that the reserve is constituted by a pulley retained by a pneumatic spring system.  3. Device according to claim 1 or claim 2, characterized in that the electropneumatic component comprises double-acting locking cylinders, and controls the approximation of the welding jaws and the release of the reserve spring.  4. Device according to any one of claims 1 to 3, characterized in that the welding component is an apparatus for welding plastics by high frequency.  5. Device according to any one of claims 2 to 4, characterized in that the detection system controls the electropneumatic component and comprises a back-and-forth device between the contactors and the jacks.  6. Device according to any one of claims 1 to 5, characterized in that it is coordinated by an electronic device.