EP0934197B1

EP0934197B1 - Process and equipment for wrapping products with stretchable film

Info

Publication number: EP0934197B1
Application number: EP97942934A
Authority: EP
Inventors: Angelo Cappi; Renato Rimondi
Original assignee: AWAX Progettazione e Ricerca SRL
Current assignee: AWAX Progettazione e Ricerca SRL
Priority date: 1996-09-24
Filing date: 1997-09-16
Publication date: 2000-12-13
Anticipated expiration: 2017-09-16
Also published as: WO1998013262A1; DE69703701D1; IT1286231B1; ES2152704T3; ITBO960473A0; EP0934197A1; ITBO960473A1; DE69703701T2

Description

For packaging products, particularly food products, there is a known method of disposing the products in a tray made of expanded polystyrene, cardboard or other suitable material, and wrapping the whole with a stretchable and transparent film, normally made of any suitable thermoplastic material (PVC-PE). There are known machines for automatically forming packages of this type, being provided with means which unwind from a reel a portion of film whose length is matched to the dimensions of the product to be packaged, which dispose this film horizontally and subject it to a suitable stretching or pre-stretching and then raise the product to be packaged and force it against this portion of film and, while the product comes into contact with the film, there is also a known method of relaxing the tension of the film adequately with what is called a back-up phase. After the product has been raised, the flaps of the film are spread and overlapped in a suitable sequence under the tray carrying the product, and the tray is discharged, while at the correct time the wrapping film is cut and separated from the film obtained from the reel. A wrapping machine or packaging machine of this type is described, for example, in US Patent No. 3.967.433 (Bonfiglioli).

Known packaging machines using stretchable film, especially those of the latest generation, while operating at low speed, are designed to optimize the consumption of film and to adapt some of their movements automatically according to the characteristics, dimensions and shape of the product to be packaged.

The various operating elements of the packaging machines of known types are generally driven by actuators powered by electrical servo motors of various types, which operate at predetermined and substantially constant speeds. The diagrams showing the movement of the various operating elements of the machines have linear and disjointed variations. Moreover, the known packaging machines are not designed to modify the operating parameters of the said motors when there are variations in the ambient temperature and in the characteristics of the film used. A packaging machine which has been designed to operate without problems at an ambient temperature of approximately twenty degrees, for example, may produce packages which are partially torn or which deform the product and the tray excessively when it operates at a temperature of approximately four degrees Celsius, which is frequently required for maintenance of the cold sequence for the conservation of certain food products. A packaging machine which has been designed to operate with stretchable film of a particular make may develop operating problems when it is supplied with a film which, although stretchable, is of another make and has physical characteristics which are even slightly different from those of the film used in the initial testing.

Document EP 0 569 615 A discloses a machine for wrapping articles in a stretchable film comprising:

means for unwinding from a reel a portion of stretchable film, whose length is proportional to the dimensions of the product to be wrapped, and means for pre-stretching the said film;
means for raising the product against the pre-stretched film, while back-up means slacken the tension of the film;
folding means which at the correct time fold and spread the flaps of the packaging film under the product which, by other means, is pushed to discharge it, while other means cut the said film and separate it from the supply reel;
electric motors with electronic speed and phase control, for driving all the above mentioned means, said electric motors being controlled by a CPU;

EP 0 569 615 also discloses a process in accordance with the preamble of claim 1.

According to the present invention, there is proposed a new process as defined in claim 1 and equipment for wrapping products with stretchable film, in accordance with the teachings of EP 0 569 615 as above disclosed and outlined, characterized by the fact that the actuators moving the various operating means mentioned above are driven by electric motors, each of which is controlled by an electronic circuit card connected by an appropriate serial link to the master CPU or CPUs of the machine, in order to make the said actuators move with variable speed, with continuous variation and with accelerations and decelerations which make it possible to obtain the best compromise between the maximum speed of movement of the said means and the maximum use of the characteristics of stretchability of the film used, without the yielding or rupture of the said film.

Further characteristics of the invention, and the advantages derived therefrom, will be more clearly evident from the following description of a preferred embodiment of the invention, illustrated purely by way of example and without restriction in the figures on the six attached sheets of drawings, in which:

Figs. 1 and 1a are diagrams of stretching at different speeds of two different types of stretchable film, the speed being applied in a known way;
Figs. 2 and 2a show with the curves in broken lines the diagrams of stretching the films shown in Figures 1 and 1a, while the curves in solid lines represent the actual stretching profile obtained with a speed varied according to the invention;
Figs. 3, 3a and 3b are speed/time diagrams of increasing stretching of films carried out by the new method;
Fig. 4 shows a possible curve which represents the equation of acceleration and deceleration necessary to maintain the maximum possible degree of continuity of the movement in the phase of stretching the film according to the invention;
Fig. 5 shows the speed curve corresponding to the preceding acceleration curve in Figure 4;
Figs. 6 and 6a show the new speed curves of the phases of unwinding and stretching of the film in a packaging machine using stretchable film;
Figs. 7 and 7a show the new speed curves for the phases of raising the product and back-up and partial closure of the wrapping film in a packaging machine using stretchable film;
Figs. 8, 8a and 8b show the new speed curves for the phases of complete closure of the tray, cutting of the wrapping film and discharge of the product in a packaging machine using stretchable film;
Fig. 9 is a block diagram of the electronic circuit which drives one of the variable speed motors of the packaging machine;
Figs. 10, 11 and 12 are flow charts for the self-regulation of the operating program of the packaging machi with the variation of the film used and relate, respectively, to: the phases of unwinding and stretching; the phase of raising the product and back-up and partial closure of the package; and the phase of discharge, complete closure of the package and cutting of the film;
Fig. 13 shows the main blocks of the self-regulation and calculation functions of the packaging machine during the normal operating cycle.

In known machines for wrapping products with stretchable film, for example in those cited in the introduction to the present disclosure or in wrapping or packaging machines of other types, the following three basic phases of manipulation of the film are present, wholly or in part: the phase of unwinding and stretching; the phase of wrapping the film around the top and sides of the tray; and the phase of total closure of the package, with the preparation of the film, if necessary, for wrapping the next product. The limitations of the known machines which carry out this type of wrapping are represented by the fact that these machines have not been designed to be able to make the best use of the physical and mechanical characteristics of the various films, since they are unable to adapt their movements to the characteristics of the stretchable films used or to the different behaviour of the films in the various situations in which they have to operate.

Each type of stretchable film used in machines of the type mentioned above or similar machines, whether it consists of PVC or PE, has its own physical characteristics which may be modified with a variation in the atmospheric conditions of the operating environment, particularly with a variation in humidity and especially with a variation in temperature, and these characteristics are also modified according to the speed at which the film is stretched and is deformed by the mechanical impact against the product raised in the packaging station.

Figures 1 and 1a are speed curves for the known stretching 13, 14, 15 and 16, 17, 18 of two films which, while they are both stretchable, have different characteristics. The film to which Figure 1 relates shows no yield before the

rupture point

113, 114, 115, while the film to which Figure la relates has

yield points

116, 117 before the

rupture points

216, 217, 218. Figures 1 and 1a show how, in the same film, the slope of the curves and the rupture and yield points vary not only with a variation of temperature, but also, and especially, with a variation of the speed of stretching of the film. The slope of these curves increases with an increase in the stretch speed and with a decrease in ambient temperature. As the stretch speed increases and the ambient temperature decreases, the percentage elongation of the stretched film decreases, and the critical rupture or yield-rupture point of the film is reached more rapidly. It should also be noted that the stretchability of a particular film is related to the width of the portion of film subjected to stretching and that it increases with an increase in the width. The packaging machines in question are designed to operate with products of different sizes and therefore must operate with packaging films with different degrees of stretching.

For a correct use of the film, it is necessary to operate not only below the rupture point, but also below the yield point, to avoid entering an uncontrollable situation which may result in the tearing of the film in the subsequent impact phase, when the product is raised and pushed against the pre-stretched portion of film. To avoid entering this uncontrollable condition and to make maximum use of the stretchability of the film, it would be possible to operate at sufficiently low speeds, for example as indicated by the

curves

15 and 18 in Figures 1 and 1a, but this would considerably restrict the output of the packaging machine and would be unacceptable. At present, the choice is made to operate at medium speed, for example as indicated by the

curves

14 and 17, with the evident compromises resulting from this choice.

The invention is designed to provide the best compromise between speed of packaging and safety of operation, with the concept of a solution illustrated in Figures 2 and 2a, according to which a move is made from the initial higher speed curve to the lower speed curve, as described in the examples shown in Figures 1 and 1a , before the critical conditions of processing the film are reached, as indicated by the curves in

solid lines

19 and 20. It is evident that the limited percentage elongations may rapidly be achieved with the new solution and that the greatest advantages are obtained when the packaging machine is required to operate on products of small and medium size, for which the width of the packaging film is limited and the stretching and stretchability of the said film are also limited.

The result of the behaviour observed previously, as seen not in the traction/percentage elongation diagram but in the speed/time diagram, is shown in Figures 3, 3a and 3b, from which it is easier to understand the complexity required to optimize the aforesaid compromise between speed and safety. The stretch curve 21 in Figure 3 shows a speed profile corresponding to a relatively small stretch, while the

stretch curves

22 and 23 in Figures 3a and 3b correspond to larger stretches and relate to films having different physical characteristics. It is evident from the curves in Figures 3, 3a and 3b that, in the passage from one stretch speed to another, phases of acceleration and deceleration are necessary to ensure that the variation of the stretching of the film is, as far as possible, continuous, progressive and constant.

In Figure 4, the curve 24 shows the profile of the acceleration and deceleration required to maintain the maximum possible degree of continuity in the movement. The curve 25 in Figure 5, however, shows the profile of the speed corresponding to the preceding curve 24.

The same considerations apply to the phases of operation of the packaging machine following the pre-stretching phase. In the phase of impact of the product against the pre-stretched film, the shock following this impact, especially if it takes place at high speed, initiates complex processes which may result in instantaneous deformations, particularly in the parts acted on by the corners of the tray containing the product, which may cause the tearing and rupture of the film.

The considerations mentioned for the other phases are also applicable to the phases of discharge of the product from the packaging station, final closure of the package and cutting of the film.

In packaging machines of the type referred to, particularly in those of the latest generation, the various moving elements are already controlled by independent electric motors, with actuators of various kinds, and in certain cases the phases of operation of these machines are co-ordinated by an electronic intelligent system which supervises the general control of the machines. The development which the invention is designed to bring about in these machines consists in creating a system in which the parameters of the movement of the individual motors, regardless of their type, and the parameters of interpolation between the various movements, are functions of the following variables:

the quality of the product to be wrapped;
the dimensions and shape of the product to be wrapped;
the elongation-yield and rupture curves of the film used, stored in a suitable way in the operating program of the machine;
the behaviour of the film with the variation of the characteristics of the atmosphere of the operating environment, in particular the temperature parameters;
the speeds relative to other simultaneous movements;
the stresses due to interaction of the film and product.

Figures 6, 7 and 8 show the speed/time diagrams relating to the operation of the motors responsible for the implementation of the main critical phases of operation of a machine for packaging products with stretchable film.

The curves 26 of Figure 6 and the curves 27 of Figure 6a represent, on the speed/time scale, one of the possible combinations of the functions of movement calculated by the machine program by means of the operating variables and parameters. They relate to the phase of unwinding and pre-stretching of the film, where the movement of the elements and the corresponding interpolations are carried out to optimize the performance and the safety of operation, with the objective of having, at the end of the said phase, a film which is uniformly stretched and therefore uniformly stressed.

The curve 28 in Figure 7 and the curve 29 in Figure 7a, however, relate to a possible result of the optimization of the second phase of manipulation of the film, relative to the back-up during the raising of the product against the film and the subsequent partial wrapping of the product. In this phase, the critical point is represented by the shock of the product which may tear the wrapping film.

Finally, the curve 30 in Figure 8, the curve 31 in Figure 8a and the curve 32 in Figure 8b relate to the movements and corresponding interpolations of the final phases of manipulation of the film for the discharge of the product, the completion of the wrapping of the product, and the cutting of the film, with preparation of the wrapping for the next tray if necessary.

The critical movements of the said motors of the packaging machine are controlled by cards shown in heavy lines in the lower part of Figure 9. Each card which controls the motors relating to the critical movements of the machine comprises its own intelligent system which monitors all the functions of communication, calculation and control of the movement and which comprises, in particular, a movement microprocessor 33, a power supply 34 which generates the necessary voltages, an EPROM 35 which contains the basic logic and the fixed programs of the system, a RAM 36 to load both the operating parameters and the variable programs sent from the other microprocessors, a control logic 37, a power unit 38 to drive the motor 101 with an encoder, and a parking brake 39 if required, and an attached input/output (I/O) logic 40. The upper part of Figure 9 shows schematically the interface to a master CPU 41 consisting of a serial connection 42 and a synchronizing I/O 43. The

numbers

44 and 45 indicate the EPROM and RAM of the master CPU and the number 46 indicates a control unit for other motors.

To make it possible to provide maximum flexibility in the individual movement and consequently maximum flexibility in the machine as a whole, the basic functions to be carried out by the control card of each motor may be listed as follows:

control of the communication with the other CPU cards to transmit and receive the operating parameters and programs;
processing of the parameters to calculate and execute the required profiles;
control of the synchronizing signals between the various CPUs in both input and output;
checking and maintenance of the synchronization of the movement of the controlled motor with that of the other motors, by means of the signals from the other controllers;
control of the execution of the movement in a correct way or in any case within the tolerances specified by the procedure followed at that moment, by means of an encoder and power factor correction sensors which also enable the movement to be synchronized in the initialization phase;
production of new movements with alternative profiles if the system is unable to provide the required profile within the specified tolerances;
transfer to the master card of the new parameters calculated in case of modification of the profile;
supply of new synchronization signals;
automatic adjustment;
test functions.

As mentioned previously in the introduction to this disclosure, another object of the invention is to make it possible for the packaging machine to operate with film having characteristics different from those of the stretchable film with which it was tested, without the need to enter critical situations which would cause tearing or rupture of the film and, especially, without the need to write the new operating programs into the machine software.

As stated previously, the principal phases during which the film may be in risk situations and which must be automatically adapted to the conditions of the said film are:

a) the phases of unwinding and stretching of the film;

b) the phases of back-up and partial closure of the wrapping;

c) the phases of complete closure of the wrapping film around the product, cutting of the film and discharge of the packaged product.

For these phases, operator-guided tests are provided, with automatic acquisition and processing of the operating parameters by the packaging machine. The self-learning test for the first group of phases will now be described with reference to the flow chart in Figure 10.

Block 47 represents " start control program". The acquisition and automatic storage program is started from the PC or from a dedicated user interface system.

Block 48 represents "select starting program". The test software starts from a basic unwinding and stretching procedure pre-existing in the machine software, to compare these data with the test data. Block 49 represents the "unwinding and stretching test start". After the starting parameters have been defined, the film unwinding and stretching parameters are defined. Block 50 represents the "unwinding and stretching start". The machine carries out the unwinding and stretching according to the specifications as drawn up. Block 51 represents "stretching stop". The machine is stopped in the position of transverse stretching of the film. Block 52 represents "record data with pocket/PC". The operator must record on the PC or on a dedicated interface system (pocket) the data required by the test program. The following inquiry table may, for example, appear on the screen connected to the PC:

UNWINDING PHASE

Unwinding carried out without rupture

YES/NO

STRETCH PHASE

Stretch carried out without rupture			YES/NO
ruptures in front part	Left □	Centre □	Right □
ruptures in central part	Left □	Centre □	Right □
ruptures in rear part	Left □	Centre □	Right □
End of recording	End of test program

When the answers YES or NO have been given, and when the boxes indicating the parts of the film affected by any ruptures have been ticked, the program is instructed to proceed with the new processing.

Block 53 represents "stop machine and remove tested film". The program stops the machine in conditions such that the operator can remove the pre-stretched portion of film on which the test has been performed. Block 54 represents "calculate new operating parameters". According to the data processed previously and the latest data entered with the test, the program calculates the new operating parameters of the machine for the phase in question. Block 55 represents "check sufficient parameters". The program checks whether the data acquired are sufficient to enable the corresponding parameters of the basic program to be processed, for adaptation to the characteristics of the film used. Block 56 is a switch dependent on whether the parameters are sufficient or not. If the parameters are not sufficient, the program moves to block 57, "calculate new unwinding and stretch", whereas if the parameters are sufficient the program moves to block 58, "calculate new program corrective data". In block 57, the program calculates the data which may still be required, prepares the machine for a new phase of unwinding and stretching and the flow returns to block 50. In block 58, the program calculates the final data for the film being tested and for the temperature of the operating environment, and enters these data in task tables. Block 59 is "calculate interpolation of various temperatures". Only if the parameters for the film tested at different temperatures are known, the complete parameters at the different temperatures are calculated with interpolations of the different data recorded. Block 60 represents "store working data". The data are stored in the PC or in a dedicated interface system and are simultaneously recorded in the store of the machine. The data can then be transferred finally from the PC or from the dedicated interface to the EPROM or RAM of all the machines. Block 61 represents "end of program".

The flow chart in Figure 11 relates to the test of the film for the aforesaid phases b) of back-up and partial closure of the wrapping. The test is conducted with sample trays to be introduced in sequence and according to specific requests of the machine program. Block 62 is "start control program". Block 63 is "select unwinding and stretch program defined by the preceding test". Block 64 represents "select start program". Block 65 represents "supply and raise tray containing product". Block 66 is "stop machine in wrapping phase". Block 67 represents "record data with PC/pocket". Block 68 represents "machine discharges product". Block 69 represents "calculate new working parameters". Block 70 is "check whether the acquired parameters are sufficient for the processing of the program". Block 71 is a switch, dependent on whether "the acquired parameters are sufficient or not". If the answer is negative, the program moves to block 72, "data on new product to be wrapped" and then to block 65. Conversely, if the acquired parameters are sufficient, the program moves to block 73, "calculate new program corrective data", then to block 74, "calculate interpolations for various temperatures", then to block 75, "store working data", and finally to block 76, "end of program".

The flow chart in Figure 12 relates to tests of the film for the aforesaid phases "c" of complete closure of the film around the tray, cutting of the film and discharge of the packaged product. In this case also, the same sample trays are used as in the preceding test. Block 77 is "start control program". Block 78 is "select unwinding and stretch program" and block 79 is "select back-up and transverse closing program". Block 80 is "select start program". Block 81 is "supply tray containing product, raise it against the film which backs up this raising and whose side flaps are spread under the tray". At block 82, the machine completes the wrapping of the product, cuts the film and discharges the packaged product. At block 83, "the data acquired at block 82 are recorded in the PC/pocket". Block 84 is "calculate new working program". Block 85 is "check whether the data acquired are sufficient". Block 86 is a switch dependent on whether the measured parameters are sufficient or not. If not, the program moves to block 87, "data on new product to be wrapped", and then returns to block 81. If the parameters are sufficient, the program moves instead to block 88, "calculate new program corrective data", then to block 89, "calculate interpolation for various temperatures", then to block 90, "store working data" and then to block 91, "end of program".

The corrective data for various types of film available on the market may be stored, possibly in advance, in the software of the machine, and each table of data is made to correspond to a specific code number. During the installation of the machine or during operation, when the decision is made to change films or to prepare the machine to operate with a known film, the new table corresponding to the type of film chosen is first selected, as indicated by block 92 of the flow chart in Figure 13 relating to the operating phase of the packaging machine. Block 92 is followed by block 93, for "selection of tray/product program", which allows for the shape and quality of the trays and of the products, and then by phase 94, for "check of operating temperature". In block 95, the program "loads the operating data for a temperature equal or close to the measured ambient temperature" and in the subsequent block 95 it "redefines the operating parameters". In block 97, it "starts the operating cycle", in block 98 "the tray containing the product enters", in block 99 "the calculations are performed according to the operating data" and in block 100 "the packaging movements are synchronized".

Claims

Process of wrapping products with stretchable film providing:

a phase of unwinding a portion of film from a reel and phases of pre-stretching the said film;

a phase of back-up of the pre-stretched film while the product is raised and forced against the said film;

one or more phases of spreading and folding flaps of the packaging film under the product, while the film is separated at the correct time by a cut from the reel from which it has been unwound, and the packaged product is discharged from the packaging station;

characterized in that each movement, in each of the said phases, is carried out with a variable speed, with continuous and cyclical variation, with precise accelerations and decelerations, in such a way as to ensure the attainment of the best compromise between the highest rate of execution of the said phases and the greatest use of the stretchability of the film without the yielding and/or rupture of the film used.
Process according to Claim 1), in which each movement and the parameters of interpolation of the various movements of the various phases of the method of packaging a product with stretchable film, are conditioned automatically by the following variables:

the characteristics of size, shape and quality of the product to be wrapped;

the elongation-yield-rupture curves of the film used;

the behaviour of the film with the variation of the temperature and humidity of the operating environment;

the relative speeds of the various simultaneous movements;

the stresses imparted by the product to the film in the phase of raising the product.
Equipment for wrapping products with stretchable film comprising:

means for unwinding from a reel a portion of stretchable film, whose length is proportional to the dimensions of the product to be wrapped, and means for pre-stretching the said film;

means for raising the product against the pre-stretched film, while back-up means slacken the tension of the film;

folding means which at the correct time fold and spread the flaps of the packaging film under the product which, by other means, is pushed to discharge it, while other means cut the said film and separate it from the supply reel;

electric motors with electronic speed and phase control, for driving all the above mentioned means, said electric motors being controlled by a CPU;

characterized in that the actuators moving the various means mentioned above are driven by the said electric motors, each of which is controlled by an electronic circuit card connected by an appropriate serial link (42) to the master CPU or CPUs (41) of the machine, in order to make the said actuators move with variable speed, with continuous variation and with accelerations and decelerations which make it possible to obtain the best compromise between the maximum speed of movement of the said means and the maximum use of the characteristics of stretchability of the film used, without the yielding or rupture of the said film.
Equipment according to Claim 3), in which the processor which controls the operation of the machine is provided with means for modifying the program for driving the motors with variable motion, according to the following variables:

the characteristics (size, shape and quality) of the product to be wrapped;

the elongation-yield-rupture curves of the film used;

the behaviour of the film with the variation of the temperature and humidity of the operating environment;

the relative speeds of the various simultaneous movements;

the stresses imparted by the product to the film in the phase of raising the product.
Equipment according to Claim 3), in which each card for controlling the variable motion motors of the packaging machine comprises: a movement microprocessor (33) connected by an appropriate serial link to the master CPU of the machine; a power supply (34) which generates the necessary voltages; an EPROM (35) which contains the basic logic and the fixed programs of the system; a RAM (36) to load both the operating parameters and the variable parameters sent from the other microprocessors; a control logic (37); a power unit (38) to drive the motor with an encoder and parking brake (39) if required, and an input/output logic unit (40).
Equipment according to Claim 5), in which the card which controls each motor with electronic speed and phase control comprises:

means for controlling the communication with the other CPU cards, to transmit and receive the operating parameters and programs;

means for processing the parameters to calculate and execute the required profiles;

means for controlling the synchronizing signals between the various CPUs in both input and output;

means for checking and maintaining the synchronization of the movement of the controlled motor with that of the motors controlled by the other cards, by means of the signals from the other controllers;

means for controlling the execution of the movement of the motor in a correct way or in any case within the tolerances specified by the procedure followed at that moment, an encoder and power factor correction sensors being provided for this purpose and also enabling the movement to be synchronized in the initialization phase;

means for producing new movements with alternative profiles if the system is unable to execute the required profile within the specified tolerances;

means for transferring to the master card the new parameters calculated in case of modification of the profile;

means for supplying new synchronization signals;

means of automatic adjustment;

means for test functions.
Equipment according to the preceding claims, in which, for the execution of the test relating to the phases of unwinding and stretching, for the automatic adaptation of the operating program of the packaging machine to the use of film of various characteristics, there are provided:

means (47) for starting the control program;

means (48) for selecting the starting program;

means (49) for processing the data for the first phase of unwinding and stretching;

means (50) for commanding the execution of the phases of unwinding and stretching according to the specifications as drawn up;

means (51) for stopping the machine in the stretching position;

means (52) to enable the operator to record on the PC connected to the machine, or on a dedicated interface system, the data required for the test program, particularly to indicate whether and where ruptures or yielding have occurred and then to instruct the program to proceed to the new processing;

means (53) for stopping the packaging machine in conditions which permit the removal of the stretched and tested film;

means (54) for making the program calculate the new operating parameters according to the data previously processed and the latest data entered;

means (55) for checking whether the acquired parameters are sufficient for the re-processing of the program;

exchange means (56) by which, if the acquired parameters are not sufficient, means (57) connected to the preceding actuating means (50) are activated to calculate a new phase of unwinding and stretching, whereas, if the data acquired are sufficient, means (58) for calculating the corrective data of the new program are activated;

means (59) for the calculation of the final data for the tested film and for the specific temperature in which the operation is carried out, these being entered in task tables;

means (60) for storing the data acquired on the PC or on the dedicated interface system and for recording them simultaneously in the store of the machine and means (61) for interrupting the test program.
Equipment according to the preceding claims, in which, for the execution of the test relating to the phases of raising the product, back-up of the film and folding the lateral flaps of the film under the product, for the automatic adaptation of the operating program of the packaging machine to the use of films having various characteristics, there are provided:

means (62) for starting the control program;

means (63) for selecting the unwinding and stretching program defined by the preceding test and dedicated for this purpose;

means (64) for selecting the starting program relating to the phase for which the test is to be performed;

means (65) for commanding the machine to supply and raise the tray containing the product;

means (66) for stopping the machine in the phase of transverse wrapping of the product;

means (67) for recording the acquired data by means of the PC or dedicated interface system;

means (68) for commanding the machine to discharge the product;

means (69) for calculating the new operating parameters;

means (70) for checking whether the acquired parameters are sufficient for the processing of the operating program;

exchange means (71) by which, if the acquired parameters are not sufficient, means are activated to obtain data on a new product to be wrapped, these means then activating the preceding means (65) of supplying and raising the product, whereas, if the data acquired are sufficient, means (73) are activated for calculating the corrective data for the new program;

means (74) for calculating interpolation at the various temperatures;

means (75) for storing the operating data and means (76) for interrupting the test program.
Equipment according to the preceding claims, in which, for the execution of the test relating to the phases of final closure of the package of the product, of cutting the film and discharge of the packaged product, for the automatic adaptation of the operating program of the packaging machine to the use of films having various characteristics, there are provided:

means (77) for starting the control program;

means (78) for selecting the unwinding and stretching program re-adapted by the preceding test;

means (79) for selecting the back-up and transverse closing program re-adapted by the preceding test;

means (80) for selecting the starting program;

means (81) for commanding the machine to supply the tray containing the product and to raise it against the unwound and pre-stretched film, while means slacken the tension of the film and fold the lateral flaps of the said film under the product;

means (82) for commanding the machine to complete the wrapping of the product, to cut the packaging film and to discharge the packaged product;

means (83) to record on the PC or on a dedicated interface system the data acquired from the preceding means;

means (84) for calculating the new operating program;

means (85) for checking whether the acquired data are sufficient;

exchange means (86) by which, if the acquired data are not sufficient, means (87) are activated to inform the machine about the characteristics of the new product to be wrapped, after which the machine repeats the packaging cycle on the new product, whereas, if the data acquired are sufficient, means (88) are activated for calculating the corrective data for the new program;

means (89) for calculation of interpolation at the various temperatures;

means (90) for storing the acquired operating data, and end-of-program means (91).
Equipment according to the preceding claims, in which, for the test phases which require the product to be raised against the pre-stretched film, as in the preceding Claims 8) and 9), sample trays are used as the product and are introduced in sequence when this is specifically requested by the machine program.
Equipment according to the preceding claims, characterized in that it comprises means for reading into the software of the packaging machine the corrective data for various types of film available on the market, and means for making each table of data correspond to a specific code number, means (92) being provided which, when the machine is to be prepared for operation with a known type of film, enable the table relating to the selected type of film to be selected, after which the following means are activated:

means (93) which permit the selection of the program for the tray/product on which the operation is to be executed;

means (94) for checking the operating temperature;

means (95) for having the data relating to the temperature equal or close to the measured ambient temperature loaded into the operating program of the packaging machine;

means (97) for starting the operating cycle;

means (98) for supplying into the machine the product to be packaged;

means (99) for executing the calculations according to the operating data;

means (100) for synchronizing the various movements of the packaging machine according to the operating program calculated by the preceding means.