WO2003084735A1

WO2003084735A1 - Apparatus for the continuous positioning of labels within dies during the moulding of plastic bottles

Info

Publication number: WO2003084735A1
Application number: PCT/IT2003/000184
Authority: WO
Inventors: Bruno Rubeca; Elpidio Rubeca
Original assignee: Co.Me.R. S.R.L.
Priority date: 2002-04-05
Filing date: 2003-03-28
Publication date: 2003-10-16
Also published as: ITRM20020190A0; AU2003219549A1; ITRM20020190A1

Abstract

An apparatus for the continuous positioning of labels within dies during the moulding of plastic bottles characterized in that there is provided a means which is able to withdraw, to transport and to release the labels and is formed of suction cap holder assemblies (E) that are moved by intermittent motion so that the withdrawal of the labels from the magazines is carried out at a speed equal to zero, and the release of the labels inside the dies (S) is carried out at a speed about equal to the traverse speed of the dies. Such apparatus is driven preferably by intermittent drive means (C) able to synchronize the movements of the label holder assembly and the dies of the bottle production machine.

Description

Apparatus for the continuous positioning of labels within dies during the moulding of plastic bottles

The present invention relates to the industrial production of bottles of plastic materials and particularly the automatic positioning of the labels within dies during the moulding of the plastic bottles.

Machines are known capable of positioning labels inside dies after having taken them from the magazine where they are collected, however, such machines are typically characterized by a poor productivity per hour as well as a limited precision in the positioning of labels. Such labels are preferably of polythenate paper so that during moulding they are molten in the plastic material which the bottle consists of. For example Graham Engineering Corporation (USA) owner of several patents relative to the production of bottles including EP0305050, EP0494539 and EP0511771 markets a rotating machine that produces hot moulded plastic bottles. Two labels are inserted into the two halves of the die of such known machine before the moulding process. The twelve dies included in the machine are arranged on a circle with a diameter of 1778 mm, one die every 30°. The drawing of the two labels from the respective magazines and their insertion inside the two half dies is carried out mechanically by a rod-crankshaft system that transforms the rotation into a linear reciprocating motion. Such reciprocating motion is used for taking, transporting and positioning the labels inside the dies.

This known device suffers from a lot of drawbacks . In fact, during the insertion step, the label is dynamically held fast, and the die moves continuously. For this reason it is difficult to position the labels exactly at the desired site without being out of line with respect to the dies and the bottle which is being formed . Moreover, when the labels are taken from the respective magazines, it may frequently occur to miss the grip, thus causing the following waste of labels be ore their insertion into the die . Therefore, such known system for positioning the labels is a limit for the quality of the processing and the productivity of the bottle moulding machines. A first object of the present invention is to overcome the above-mentioned problems by providing an apparatus for positioning the labels wherein the step of inserting labels into the dies is carried out with the labels moving by a translation movement parallel to and in phase with the dies so that there is no relative movement between labels and dies. A second object of the invention is to provide an apparatus in which the withdrawal step of the labels from the respective magazines is carried out with the suction caps being under still conditions for enough time as to ensure a correct grip. This has been accomplished according to the invention by providing a withdrawal and positioning rotating apparatus driven by intermittent drive means able to synchronize the movements of the label holder assemblies and the dies of the bottle production machine as described thereafter.

A better understanding of the invention will follow from the following description with reference to the accompanying drawings that show only by way of a not limiting example a preferred embodiment thereof. In the drawings :

Figure 1 is an operation diagram of the Graham machine with labelling machine put in reciprocating motion by means of a rod/crankshaft system;

Figure 2 is an operation diagram of the label positioning in the dies according to the invention;

Figure 3 is a more detailed view than figure 2;

Figures 4 and 5 are front and side views of the apparatus of the present invention, respectively;

Figure 6 shows the initial, intermediate, final positions taken by the suction cap holder carriage during the positioning of the labels into the dies;

Figure 7 is a three-dimensional view showing in greater detail than fig. 6 the movement of the suction cap holder carriage during its passage on the linear cam;

Figure 8 shows schematically the detail relative to the elastic means carried by each arm of each suction cap holder carriage;

Figure 9 shows the pneumatic operating diagram of the suction cap holder carriages according to the invention;

Figure 10 shows in detail the two arrangements of a suction cap holder carriage: upon releasing and upon withdrawing-gripping the labels;

Figures 11 and 12 are diagrams showing two arrangements to drive the suction cap holder carriages: belt drive and sprocket wheel-rack drive.

SHORT SUMMARY OF THE INVENTION With reference to the figures mentioned above, there is provided according to the invention an apparatus for positioning labels including at least a roller chain C to which suction cap holder assemblies PV able to seize labels E and to release them into dies S are anchored.

A peculiar feature of the invention is that such chain has an intermittent motion with stopping intervals during which at least one carriage PV takes labels E, and moving intervals during which one carriage moves in synchronism with one die S and leaves inside it the labels withdrawn.

In particular (fig. 2) such chain is moved by an intermittent drive means I which causes the output axis to rotate partially at each complete rotation of the input axis, followed by a stop.

With further reference to figures 3 to 6, the apparatus of the present invention provides an essential correspondence between speed and path of dies S and suction cap holder assemblies PV during the step of positioning labels E inside the dies. This is accomplished preferably by connecting in a suitable manner the input shaft of the intermittent drive means I to the bottle moulding machine. The advantages of the invention are better appraised if it is considered that the solution described has a production rate of 60 bottles per minute (i.e. a cycle time of 1,0 second per bottle) . Under such circumstances, a time of 0.34 second is needed to withdraw labels by the suction cap holder carriages still standing at the label magazines. During the following time of 0.66 second, in which the carriages move synchronously and with the same phase as the dies, the labels are inserted with high precision inside the dies S by means of a linear fixed cam CL that pushes the suction cap and then labels E to the outside, as can be better seen thereafter. It should be noted that, if it is assumed a production rate of 50 bottles per minute, i.e. a cycle time of 1.2 second per bottle, in the currently known machines, one of them is shown schematically in figure 1 only by way of example, only a time of 0.6 second can be used to withdraw the labels, to transport them vertically by about 500 mm and to insert and release the same into the dies. The following time of 0.6 second is used by the empty suction cap holder assembly to return to the label withdrawal position.

DETAIL ED DESCRIPTION

In the preferred embodiment shown in figures 3 and 4 , the apparatus described includes a double chain circuit C carrying eight suction cap holder carriages PV.

In the cycle time necessary for the production of a bottle and required by the machine for the moulding, the chain circuit C needs 2/3 of the available time, i.e. the cycle time, to accelerate until a speed which is almost the same as the peripheral speed of the dies is reached, to release the label inside the die, and to decelerate to come to a stop. In the following 1/3 of the available time, the apparatus is standing still, and the suction caps of one carriage PV take labels E from the relative magazines.

During the movement synchronized with the dies, each suction cap holder carriage PV crosses the linear cam CL from position 1 to 3 (fig. 6) , extends the two suction cap holder arms inside the die (position 2) , releases labels E, and retracts the two arms to come to a stop at the end of the step. Such arms extend to a transversal direction with respect to the traverse direction of carriage PV. Figure 7 shows very clearly a three-dimensional view of the sequential positions of each suction cap holder carriage PV during its traverse on the linear cam CL. The first drive cursor 10 of carriage PV slides sideways as it is shifted by the lower drive bearing 11 which slides inside cam CL, reaches the end of stroke (figure 7, left) , and returns to the initial position (right end of stroke in figure 7) . During such reciprocating motion drive cursor 10 causes the two extensible arms 12 to reach the maximum extension at the end of stroke of the cursor (position 2 of carriage PV) .

It is selfrevident from the figures that one of the two arms 12 in this embodiment is moved directly from the drive cursor 10, and the other arm is moved by a second cursor 10' driven by a belt 20 which is stretched between two pulleys carried by the carriage at the two . limit stops of the second cursor 10' . Of course, it should be noted that the two cursors are connected to opposite branches of belt _.20 so that they always move against each other.

Advantageously, according to a further peculiar feature of the present invention, each arm 12 of any carriage is provided with elastic means to compensate for the extension stroke and to prevent that ^• any misalignment between the label positioning apparatus and the bottle moulding machine can cause the mechanical parts to break or to come to a dangerous crawling. In the present embodiment (fig. 8) such compensation means consists of springs 13 interposed between transmission means driving arms 12 and the ends of the latter. Thus, if one or both arms reach the bottom of the die before the actual end of stroke is reached, the transmission means driving the arms can reach the end of their strokes without damaging the arms or the suction caps of the dies. In fact, such springs 13 have an extension stroke CM able to provide for any excessive shift that can be made by the transmission means driving arms 12 but not by the latter.

It should be appreciated that such feature is particularly important to limit the maintenance to keep the right position and alignment between the disclosed apparatus and the bottle moulding machine in time. It is instead necessary to keep the right reciprocal alignment in the embodiments of the state of art in which the only allowed positioning "error" is what can be compensated by the elasticity of only the suction cap carrying the labels, then it is very limited or in practice null.

With reference to figure 9, it is very interesting now to go deep into a disclosure of the motions of the whole apparatus that is intermittently moved, as mentioned above, to allow both to take labels E when the suction cap holder carriage PV is stationary and to release the same inside dies S when such carriage is moving at almost the same speed as the dies so that the relative speed between labels and dies is essentially null. In the disclosed embodiment the invention is adapted to a machine produced by Graham Engineering Corp.

(USA) provided with twelve dies, the symmetry axes of which are tangential to a circumference with a radius of 889 mm, the dies being then disposed at angular intervals of 30°.

As mentioned above, according to the present invention it is necessary that the linear velocity of the suction cap (as well as the labels) and the peripheral speed of the die are equal or have very near values when the label is transferred from the suction caps to the die so that the positioning of the labels into the dies is carried out correctly.

As disclosed, the embodiment illustrated in the above figures includes a double chain circuit C for the transport of eight groups of suction cap holder carriages PV. Chains having a pitch %" , i.e. 19.05 mm, are used. The pitch of the carriages is 228.6 mm equivalent to 12 links. The suction cap holder carriages PV withdrawn by the chain circuit C are moved by an intermittent drive means I (fig. 2) which is in turn driven by the Graham machine with a transmission ratio of 12:1 so that every rotation by 30° of. the circle on which the dies rotate corresponds to a rotation by 360° of the input axis of the intermittent drive means.

The disclosed device provides that every rotation by 360° of the input axis of intermittent drive means I corresponds to a rotation by 240° of the output axis more 120° interval. Through the proper data of intermittent drive means I one can determine the motion mode of the suction cap holder carriages PV carried by the double chain circuit .

In particular, a rotation by 240° of the output axis of the intermittent drive means is formed by 75° acceleration, 90 ° constant speed, and 75° deceleration. The step of constant speed is carried out at an angular velocity of 8.8221 radiant/second. For construction reasons the output axis of the intermittent drive means is connected to the drive axis of the chains by a transmission ratio of 0.75, and the crown gear driving the chains have a primitive diameter of 145.94 mm. Therefore, the linear velocity of the carriages during the constant speed step has the value of: 8.8221 x 0.75 x 72.97 = 482.806 mm/sec equal to 28.96 m/min.

The peripheral speed of the die at 60 bottle per minute and with the machine rotating at 5 rpm is: 889 x 6.28 x 5 = 27928.75 mm/min (=465.479 mm/sec) equal to 27.92 m/min.

The speed difference between label and die at the time of release is:

Viabei - V_die = 28.96 - 27.92 = 1.04 m/min.

In the example shown the distance covered by the die and the carriage with labels E in contact with the inside of the die is 15 mm. The theoretical positioning error due to the difference is then given by the difference between the distance covered by the labels and that covered by the dies in the same time : t = 15 mm/Vi_abei = 15/28968.36 = 0.031 sec. (V_di_e x t = 465.479 x 0.031 sec) = 14.43 mm Error = 15 - 14.43 + 0.57 mm

Advantageously, such error does not add to the preceding errors as the intermittent operation of the carriages sets the errors at zero at the beginning of each cycle of label shift and release.

Labels are withdrawn from the magazine preferably by causing arms 12 of each carriage PV to extend by a suitable pneumatic cylinder driven by an encoder upstream of intermittent drive means I .

A variation of the invention relative to label withdrawal provides the replacement of the pneumatic cylinder by a mechanical oscillator that allows a better control of the early driving of the carriage under low running conditions or during transients after the starting of the system from the stationary state . Actually, even if the productivity, i.e. the number of bottle per minute, is changed the withdrawal by a mechanical device would make the variation of the above-mentioned early driving automatic, while the use of the pneumatic cylinder driven by the encoder requires the early driving to be adjusted- exactly for each amount of productivity.

The diagram of figure 10 shows the pneumatic circuit associated to each eight suction cap holder carriages PV in the label positioning machine of the invention. When the encoder energizes electrovalve 1 (figure 10, below) compressed air flows through rotating collector 7 and supplies the respective vacuum pump 2 driving at the same time slide valve 3 and supplying the following carriage with air 6.

Thus, the holes formed in each suction cap 4 are subjected to a depression, thus allowing the labels to be withdrawn and held until the encoder deenergizes electrovalve 1 to release the labels inside the two half dies. Upon deenergizing valve 3 (figure 10, above) air 5 from the preceding carriage is allowed to supply the above holes in suction caps 4.

According to a possible variation of the invention shown in the diagram of figure 12, suction cap holder carriages PV provide an always engaged mechanical drive of the sprocket wheel-rack type. In this case, of course, drive cursor 10 which is moved by the control bearing 11 sliding in the linear cam CL is integral with one arm 12, while the other arm is moved to the opposite direction by a pinion or sprocket wheel P to which both arms are engaged by suitable racks 21. It should be appreciated that such pinion or sprocket wheel P rotates about an axis perpendicular to the plane on which arms 12 are moved and is integral with the carriage. The present invention has been described and illustrated according to its preferred embodiments, however, it should be understood that anyone skilled in the art can make technically or functionally equivalent modifications and/or replacements without departing from the scope of the present industrial invention.

Claims

1. An apparatus for the continuous positioning of labels within dies (S) during the moulding of plastic bottles characterized in that there is provided a means (PV) which is able to withdraw, to transport and to release the labels (E) and is formed by suction cap holder assemblies that are moved by intermittent motion so that the withdrawal of the labels (E) from the magazines is carried out at a speed equal to zero, and the release of the labels inside the dies (S) is carried out at a speed about equal to the traverse speed of the dies (S) .

2. The apparatus according to claim 1, characterized in that there is provided an intermittent drive means (I) able to synchronize the movements of both the label holder assembly (PV) and the dies (S) of the bottle production machine.

3. The apparatus according to any preceding claim, characterized in that at least a roller chain (C) is included to which said suction cap holder assemblies (PV) able to seize labels (E) and to release them into dies (S) are anchored.

4. The apparatus according to the preceding claim, characterized in that such chain has an intermittent motion with stopping intervals during which at least one suction cap assembly or carriage (PV) takes labels (E) , and moving intervals during which one carriage moves in synchronism with one die (S) and leaves inside it labels (E) withdrawn.

5. The apparatus according to the preceding claim, characterized in that said chain is moved by an intermittent drive means (I) which causes the output axis to rotate partially at each complete rotation of the input axis, followed by a stop.

6. The apparatus according to the preceding claim, characterized in that there is provided a drive means that provides an essential correspondence between speed and path of suction cap holder assemblies (PV) and dies (S) during the step of positioning labels (E) inside the dies, this being accomplished for example by connecting in a suitable manner the input shaft of the intermittent drive means (I) to the bottle moulding machine.

7. The apparatus according to the preceding claim, characterized in that in the cycle time necessary for the production of a bottle and required by the machine for the moulding, the chain circuit (C) needs 2/3 of the available time, i.e. the cycle time, to accelerate until a speed which is almost the same as the peripheral speed of the dies (S) is reached, to release the label inside the die, and to decelerate to come to a stop, so that the apparatus is standing still in the following 1/3 of the available time, and the suction caps of one carriage (PV) take labels (E) from the relative magazines.

8. The apparatus according to the preceding claim, characterized in that at the production rate of 60 bottles per minute (i.e. a cycle time of 1.0 second per bottle) a time of 0.34 second is needed to take labels (E) by the suction cap holder carriage (PV) standing still at the label magazines, during the following time of 0.66 second, in which the carriages move synchronously and with the same phase as the dies

(S) , the labels being inserted with high precision inside dies (S) by means of a linear fixed cam (CL) that pushes the suction caps of the carriages (PV) and then labels (E) to the outside.

9. The apparatus according to the preceding claim, characterized in that there is provided a double chain circuit (C) transporting eight suction cap holder carriages (PV) .

• 10. The apparatus according to any preceding claim, characterized in that during the movement synchronized with the dies each suction cap holder carriage (PV) crosses a linear cam (CL) from the initial to the final positions by extending two arms (12) provided with suction caps inside die (S) (intermediate position) and releasing labels (E) , and retracts the two arms to come to a stop at the end of the step, said arms (12) extending to a transversal direction with respect to the traverse direction of carriage (PV) .

11. The apparatus according to the preceding claim, characterized in that during crossing linear cam (CL) a first drive cursor (10) of carriage (PV) slides sideways as it is shifted by the lower drive bearing

(11) which slides inside cam (CL) until the end of stroke is reached, and returns to the initial position, during such alternate movement drive cursor

(10) causing the two extensible arms (12) to reach the maximum extension at the end of stroke of the cursor by mechanical means and to return to their initial position.

12. The apparatus according to the preceding claim, characterized in that one of the two arms (12) is moved directly from the drive cursor (10) , and the other arm is moved by a second cursor (10') driven by a belt (20) which is stretched between two pulleys carried by the carriage at the two limit stops of the second cursor (10'), the two cursors being connected to opposite branches of belt (20) so that they always move against each other.

13. The apparatus according to claim 11, characterized in that one of the two arms (12) is moved directly from the drive cursor (10) which is moved by the control bearing (11) sliding in the linear cam (CL) , while the other arm is moved to the opposite direction by a pinion or sprocket wheel (P) to which both arms are engaged by suitable racks (21) , such pinion or sprocket wheel (P) rotating about an axis perpendicular to the plane on which arms (12) are moved and being integral with the carriage.

14. The apparatus according to any claims 10 to 13, characterized in that each arm (12) of any carriage is provided with elastic means (13) to compensate for the extension stroke and to prevent that any misalignment between the label positioning apparatus and the bottle moulding machine can cause the mechanical parts to break or to come to a dangerous crawling.

15. The apparatus according to the preceding claim, characterized in that such compensation means consists of springs (13) interposed between the transmission means driving arms (12) and said arms.

16. The apparatus according to claim 7, characterized in that in order for the linear shift speed of labels (E) is equal or almost equal to the peripheral speed of die (S) when the label is transferred from the suction cap to the die, it is provided that every rotation by 360° of the input axis of intermittent drive means (I) corresponds to a rotation by 240° of the output axis more 120° interval.

17. The apparatus according to the preceding claim, characterized in that the rotation by 240° of the output axis of the intermittent drive means is formed by 75° acceleration, 90° constant speed, and 75° deceleration .

18. The apparatus according to any preceding claim, characterized in that labels are withdrawn from the magazine by causing arms (12) of each carriage (PV) to extend by a suitable pneumatic cylinder driven by an encoder .

19. The apparatus according to any claims 1 to 17, characterized in that labels are withdrawn from the magazine by causing arms (12) of each carriage (PV) to extend by a suitable mechanical oscillator that allows a better control of the early driving of the carriage under low running conditions or during transients after the starting of the system from the stationary state.

20. The apparatus according to any preceding claim, characterized in that each suction cap holder carriage (PV) is provided with a pneumatic drive means including an electrovalve (1) energized by a suitable encoder receiving compressed air through a suitable rotating collector (7) to supply a respective vacuum pump (2) and to drive at the same time a corresponding slide valve (3) and to supply the following carriage with air, thus providing that the holes formed in each suction cap (4) are subjected to a depression, thus allowing the labels to be withdrawn and held until the encoder deenergizes electrovalve (1) to release the labels inside the two half dies.

21. The apparatus according to the preceding claim, characterized in that upon deenergizing valve (3) , air from the preceding carriage is supplied to the above holes in suction caps (4) .