ES2691958T3 - Expandable film loading machine with extensible film - Google Patents

Abstract

A machine for packaging a vertical and upper surface of loads (13) with extensible film that has a base frame (1), a rotary table (2) mounted on it and a mast (3) fixed on the base frame (1), a carriage (4) that vertically moves a film reel (7) is fixed on the mast (3), bushings (5) are formed on the carriage (4), a tree (6) is inserted to Through it, a tilt actuator (8) is connected to one end and a film reel (7) is connected to the other end of the shaft (6) and a home position sensor (9) and a position sensor. horizontal (10) are arranged on the base frame (1), some activation flags (12A, 12B, 12C, 12D) of the inclination control associated with the corners (14) of the load (13) and an element of activation (11) of the initial position are fixed to the rotary table (2), it is provided with a tension adjustment unit (22) of the oscillating film with attached to the other end of the shaft (6), whose unit has pre-extension rollers (7A) provided with a pre-extension motor (20), a front roller (7B) that contains an arm provided with a roller (7C) , a pneumatic pressure adjusting cylinder (16) provided with an analog displacement transducer (17) and equipped with a piston provided with a magnet (16A), in addition a pressure regulator (18) is fixed to the frame of the unit of film retention and pre-extension (23), where the film unwound from the film reel (7) is driven between pre-extension rollers (7A) one connected to the other with a transmission (19) and one of them it is driven by the pre-extension motor (20), then the film is fed around a front roller (7B) which has a rotating arm around a center of rotation and the arm is provided with a roller 7C), is connected to the piston provided with magnet (16A), which is mounted on a pneumatic cylinder of aj tension (16), characterized in that the pressure regulator (18) - which is in connection with the pneumatic tension adjusting cylinder (16) which is regulated by the resultant of the pressure and the pulling force of the film - it is applicable to adjust a reference value and various presetting of the pressure therein, the pneumatic tension adjusting cylinder (16) is in connection with the analog displacement transducer (17), which is in signal connection with a frequency changer (15), which regulates the speed of the pre-extension motor (20).

Description

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DESCRIPTION

Expandable film loading machine with extendable film

The invention relates to a machine for packing loads with extensible film.

The vertical and top surface of the loads can also be packed using the machine.

There is a wide variety of machines for extensible packing of loads known in practice.

Using a machine described in the German publication of registration number DE 3633680, the load is placed on a rotating table and a retractable cap made of retractable film is placed on the load.

The load wrapped with the retractable cap is rotated by the rotating table and a burner nozzle fixed on a mobile carriage vertically retracts the upper and lower parts of the retractable cap circularly and the lateral part along a line of screw making a movement programmed.

The application of the retractable cap can provide adequate protection to the load due to the packing of the upper part of the load.

The disadvantage of the machine is that the retraction bell must be previously manufactured and placed on the load. The manufacture of the cap requires labor, in addition to the specific demand for film is large, as well as the energy requirement of the retraction is also quite large.

In the last decade, the packaging of significantly effective cost with extensible film is applied to an increasing degree due to the aforementioned drawback of the shrink film packaging.

The specific demand for a film with an expandable film represents approximately one fifth of the retractable bell and there is no high requirement of energy necessary for the retraction. The common distinguishing characteristics of the simplest manual machines and the fully automatic machines applied to the extensible film packaging are that they have rotating tables and an applicable carriage for the vertical movement of the film.

The aforementioned structural units of the machines make it possible for the pre-extended film to wrap the load along a screw line as a result of the movement of rotation of the load and the vertical movement of the film. The length of the film, the overlap and the number of the windings can be changed depending on the properties of the load and the fixing requirements. Patent specification HUP 210302 describes a very advantageous applicable machine that allows the extendable packaging of loads with film also extendable on the upper surface of the load with the film applied to pack the side surface.

The solution ensures the perfect protection of products through the continuity of the film, making it unnecessary to apply a retractable bell in this way.

The essential of the machine according to the solution is that the film applied for the extensible packaging of the lateral surface of the load by winding along a screw line is conducted above the load and tilts from the lateral position up to the vertical position during a downward movement and the envelope of the upper part is carried out in this way.

The machine according to the patent has a base frame, a turntable mounted therein and a mast fixed on the base frame. A car that moves vertically the film is mounted on the mentioned mast and a bushing is supporting the car.

A tree is inserted into the bushing and a film reel is connected to one end and the tilt actuator is connected to the other end of the tree.

A sensor for the vertical (basic) position and a sensor for the horizontal position are mounted on the base frame, which activate banners mounted on the turntable associated with the corners of the load, as operating elements that control the inclination.

The disadvantage of the machine is that the value of the tensile tension can only reach the closest digital value according to the values of the stages, so that it can not be followed proportionally, therefore it is not possible to adjust the tension of the the movie.

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Since the tension changes continuously, the film can occasionally be torn by the sharp corners of a load. There is another problem that the film can break inside the corners of the lower layers more loaded with the loads packed in cardboard boxes and corrugated paper.

An extended solution consists of detecting the tension of the film by driving the film around an oscillating axis loaded with a spring. Using this solution, when the tension of the film between the load and the pre-stretching unit increases, the spring-loaded oscillating arm is forced to deflect and there are digital sensors (normally inductive) arranged along the circular arc described by the tree, and the sensors transmit signals of discrete values on the tension of the film to the control system, which responds to them by changing the braking force of the film.

According to another solution, the oscillating arm which is deflected along a circular arc under the influence of the tension of the film is attracted or driven by one or more springs with almost constant force - between the two extreme positions of the deviation - to the direction that corresponds to the minor tension of the film. The problem with this solution is that the force of attraction or thrust of the springs is not linear along the length of traction or thrust, therefore a pre-extension unit does not have a linear behavior, but progressive.

A possible consequence of this operation is that a combined machine with digital control is susceptible to oscillation and adjusts the tension of the film in a wide range. Consequently, excessive tension can result, which can lead to tearing or loosening. It can even cause a winding of the film on rubber coated cylinders and force the stoppage of the packaging process. The pre-extension of the film loaded by spring has also another problem that can not be adjusted, repeated and measured.

We have not proposed the task of developing an improved machine that eliminates the aforementioned drawbacks.

The patent description of USP 4706443 describes a packaging machine and the packaging operation and the operation of packaging the load with extensible film under substantially constant tension during the packaging operation.

This machine is provided with pre-extension rollers (18, 32), pre-extension motor (20), an oscillating arm (40) provided with roller (38), an air cylinder (52) with piston (54) .

The machine is provided with an air regulator and a motor control (88).

The machine of the previous patent is able to pack only the lateral surfaces of the load on platform by extensible film, trying to avoid the breakage of the film, acting mainly on the edges delimited by two neighboring planes of the load.

The constant tension of the film, as mentioned in the title of the patent, should be understood as a tension that changes restrictively between two limits.

The patent machine is only able to change the speed of advancement of the film after passing over the lower level and the upper level of the tension of the film.

The machine can not intervene in the intermediate positions, as shown in figure 8 of the description.

The "constant" tension of the film can only be understood between certain limits.

The machine according to the patent is used to minimize breakage on the edges, and is not effective enough to avoid breaking the film at the corners.

The engine of the previous patent is a DC motor.

In the solution of USP 4458467 a conventional extendable packaging machine is used which is capable of packing only the lateral surfaces of the load by extendable packaging machinery.

In the description of the patent they only try to avoid breaking the film at the edges delimited by the neighboring planes of the load. In the solution, DC motors are used.

The object of our invention is to develop a machine for packing the vertical and top surface of loads with extensible film.

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The machine of our invention follows the angular displacement directly proportional to the tension of the film between the load and the pre-extension rollers with the signals of an analog displacement transducer.

The analog displacement transducer can not only accept a small number of digital values, but even several hundred individual values.

In our solution, the measurement of the tension is more exact, the regulation action is faster and the difference of the tensions to be compensated is less.

The pre-extension motor responds more quickly, more accurately and with less redundancy under the influence of increased tension.

The required value of the tension of the film can be approximated and maintained better by means of the regulating action of the increased accuracy during the entire duration of the packaging.

Our solution was not evident to an expert after full knowledge of the description of USP 4706443 and USP 4458467.

In our invention, an analogue displacement transducer emits signals to a frequency changer, which is characterized by the resultant adjustment of the pressure and the pulling force of the film.

The frequency changer can regulate the speed of rotation of the pre-extension motor until the amount of the film becomes equal for packing the vertical and top surface of the load.

The subject matter of the invention is a machine for packaging a vertical and upper surface of loads with extensible film having a base frame, a rotating table mounted on it and a mast fixed on the base frame, a moving carriage vertically a film reel is fixed on the mast, some ferrules are formed on the carriage, a tree is inserted through it, a tilting actuator is connected to one end and a film reel is connected to the other end of the tree and a sensor of the initial position and a sensor of the horizontal position are disposed on the base frame, banners of activation of the control of the inclination associated with the corners of the load and an activation element of the initial position are fixed to the rotary table, is provided with a unit of adjustment of the tension of the oscillating film connected to the other end of the tree, whose unit has pre-extension rollers pr Equipped with a pre-extension motor, a front roller containing an arm provided with a roller, a pneumatic pressure adjusting cylinder provided with an analog displacement transducer and equipped with a piston provided with magnet, plus a pressure regulator is fixed to the frame of the retention and pre-extension unit of the film, where the film unrolled from the film reel is driven between pre-extension rollers one connected to the other with a transmission and one of them is driven by the pre-extension motor, then the film is fed around a front roller that has a rotating arm around a center of rotation and the arm is provided with a roller, is connected to the piston provided with magnet, which is mounted on a cylinder pneumatic adjustment of the tension.

The characteristics of the machine are the following: the pressure regulator - which is in connection with the pneumatic cylinder of adjustment of the tension that is regulated by the resultant of the pressure and the traction force of the film - is applicable to adjust a reference value and several pre-adjustments of the pressure in the same, the pneumatic cylinder of adjustment of the tension this in connection with the analog displacement transducer, which is in connection of signals with a frequency changer, which regulates the speed of the pre-extension engine.

The turntable of the machine is driven by a drive motor of the turntable.

The piston provided with magnet of the machine moves between two extreme positions in relation to a reference value adjusted through the pressure regulator.

The machine according to the invention is shown in figures 1 and 2.

Figure 1 shows the schematic representation of the machine, while figure 2 shows the regulating elements of the machine and its connections.

Figure 1 shows an advantageous embodiment of the machine. The solution covers other machines other than this, which have more than two pre-extension rollers and their drive can be identical or different from the one shown.

The base frame 1, the rotary table 2 mounted on it and the load 13 positioned on the rotary table

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they are shown in figure 1.

The carriage 4 that moves vertically the film reel 7 is fixed to the mast 3 mounted on the base frame 1 and the bushing 5 is formed on the carriage 4.

A shaft 6 is inserted in the sleeve 5, a tilting actuator 8 is connected at one end and a tension adjusting unit 22 of the film is connected to the other end thereof.

The initial position sensor 9 and the horizontal position sensor 10 are arranged on the base frame 1 with activation flags 12A, 12B, 12C, 12D (control of the inclination) to control the inclination associated with the corners of the load 14, as well as a sensor of the initial position 9 are mounted on the rotary table 2.

The tension adjustment unit 22 of the film fixed to the frame of the retention and pre-extension unit of the film 23 has pre-extension rollers 7A provided with a pre-extension motor 20, a front roller 7B which it contains an arm provided with a roller 7C, a pneumatic tension adjusting cylinder 16 having an analog displacement transducer 17 and supplied with a piston provided with magnet 16A, a pressure regulator 18 and a frequency changer 15.

The film unrolled from the film reel 7 is fed between the pre-extension rollers 7A connected together with a transmission and one of which is driven with the pre-extension motor 20, then the film is driven around a roller front 7B having an arm that moves around a center of rotation and the arm is provided with a roller 7C.

The arm provided with the roller 7C is connected to a piston provided with magnet 16A and the magnet-equipped piston 16A is disposed in a pneumatic tension adjusting cylinder 16 provided with an analog displacement transducer 17.

The piston provided with magnet 16A is connected to a pressure regulator 18 and a frequency changer 15. The frequency changer 15 is also connected to the pre-extension motor 20 of the pre-extension rollers 7A.

The rotary table 2 is driven by a drive motor 21 of the turntable.

The piston provided with magnet 16A is moved by a pressure regulator 18 between two end positions relative to the adjustment reference value.

We apply the SM6 product from the company Bosch Rexroth or the SMAT from the company Festo as analog displacement transducer 17.

The transmission 19 may be of any usual type, advantageously one with chain, V-belt, gears, synchronization belt, etc.

Figure 2 shows the pneumatic adjustment cylinder of the tension 16 having the piston provided with magnet 16A and the analog displacement transducer 17 connected to the pressure regulator 18.

The machine contains a pneumatic tension adjustment cylinder 16 equipped with a piston provided with magnet 16A, loaded on one side and a pressure regulator 18 connected thereto, applicable to adjust the tension of the film relative to a reference value objective. The tension adjusting pneumatic cylinder 16 is provided with an analog displacement transducer 17 which measures the position of the piston provided with magnet 16A. The transducer transforms the position into an electrical signal that characterizes it and regulates with it the preextension motor of the film 20 through a frequency changer 15. In the case of the traction force that characterizes the tension of the If the film is less than the original reference value set by the pneumatic tension adjustment cylinder 16 and the pressure regulator that belongs to it, the piston provided with magnet 16A moves towards an extreme position.

The rotation speed of the pre-extension motor 20 is then decreased; it wraps the load 13 with less film for one unit of time until the amount of film during the unit of time is equal to or less than the amount sufficient to pack the load 13.

The load 13 "pulls" the film due to it, extends and the force that characterizes its tension moves the arm provided with roller 7C towards the position that characterizes the tensioned film. The piston provided with magnet 16A of the tension adjusting pneumatic cylinder 16 will move to the other end position at the same time. Accordingly, the analog shift transducer 17 sends an acceleration signal to the frequency changer 15, which sends an acceleration signal to the pre-extension motor 20.

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The current position of the piston provided with magnet 16A is regulated by the resultant adjustment of the pressure and the traction force that results on the film. The pulling or pushing force of the pneumatic cylinder for adjusting the tension 16 can be adjusted over the entire length of the trajectory, the pressure can be measured, so that the extension force can be repeated.

The horizontal axis of the tension adjusting unit 22 forms an angle of twenty-five degrees with the radial direction of the main rotational movement, so that the upper edge of the film returned to the horizontal on the real or imaginary center side of the Main rotational movement does not lengthen to such a large extent that it could reduce the retraction capacity.

The advantages of the machine according to the invention are the following: it follows an angular displacement directly proportional to the tension of the film between the load 13 and the pre-extension rollers 7A with an analog signal of an analog displacement transducer 17, that can accept only a small number of digital values, but several hundred individual values. The measurement of the tension is more exact, the action of regulation is faster and the difference of the tensions to be compensated is less.

The pre-extension motor 20 responds more quickly, more accurately and with less redundancy under the influence of increased tension.

The required value of the film tension can be approximated and maintained better by means of the increased accuracy regulating action during the entire duration of the packaging.

The tension adjustment unit 22 of the oscillating film, which can be operated with motor-driven pre-extension and with several presettings of the pressure, adjustable in an analogical manner, can be a separate complement of the packaging machine with Extendable film, which can be formed in all types of packaging machines with extensible film, for example in constructions with rotary arm or rotating ring, and the film packaging can be solved in a packaging machine with extensible film of any type with a relatively small cost using an extendable film used to pack the side surfaces of the load 13.

List of symbols

1 Base frame

2 Rotating table

3 Mastil

4 Cart

5 Cap

6 Tree

7 Film reel

7A Pre-extension rollers

7B Front roller

7C Arm provided with roller

8 Lifting actuator

9 Initial position sensor

10 Horizontal position sensor

11 Element of activation of the initial position

12A, B, C, D Banners of activation (control of the inclination)

13 Load

14 Corners of the load

15 Frequency changer

16 Pneumatic cylinder for adjusting the tension

16A Piston provided with magnet

17 Analog displacement transducer

18 Pressure regulator

19 Transmission

20 Pre-extension motor

21 Rotary table drive motor

22 Unit for adjusting the tension of the film

23 Retention and pre-extension unit frame

Claims (1)

1. A machine for packaging a vertical surface and top of loads (13) with extensible film having a base frame (1), a rotating table (2) mounted on it and a mast (3) fixed on the base frame 5 (1), a carriage (4) that moves vertically a film reel (7) is fixed in the mast (3), some ferrules (5) are form on the carriage (4), a tree (6) is inserted through it, a tilt actuator (8) is connected to one end and a film reel (7) is connected to the other end of the tree (6) and an initial position sensor (9) and a horizontal position sensor (10) are provided on the base frame (1), associated activation flags (12A, 12B, 12C, 12D) of the inclination control to the corners (14) of the load 10 (13) and an activation element (11) of the initial position are fixed to the rotary table (2), it is provided with a tension adjustment unit (22) of the oscillating film connected to the other end of the tree (6), whose unit has pre-extension rollers (7A) provided with a pre-extension motor (20), a front roller ( 7B) containing an arm provided with a roller (7C), a pneumatic pressure adjusting cylinder (16) provided with an analog displacement transducer (17) and equipped with a piston provided with magnet (16A), plus a regulator 15 (18) is fixed to the frame of the retention and pre-extension unit (23) of the film, where the film unrolled from the film reel (7) is driven between pre-extension rollers (7A) one connected to the other with a transmission (19) and one of them is driven by the pre-extension motor (20), then the film is fed around a front roller (7B) having a pivoting arm about a center of rotation and the arm is provided with a roller 7C), is connected to the piston provided with magnet (16A), which is mounted on a cylinder pneumatic tension adjustment (16), characterized in that the pressure regulator (18) - which is in connection with the pneumatic tension adjustment cylinder (16) which is regulated by the resulting pressure and force of traction of the film - is applicable to adjust a reference value and several pre-adjustments of the pressure in it, the pneumatic cylinder of adjustment of the tension (16) is in connection with the analog displacement transducer (17), which is in connection of signals with a changer d e frequency (15), which regulates the speed of the pre-extension motor (20).