Guiding and calibration device for blown plastic film with sliding bars

Abstract

A guiding and calibration device (100) of a blown plastic film is described, comprising a bearing structure (1, 2) which includes equidistant rotation fulcrums (3) of rotating structures (4) along an ideal circumference. Each rotating structure (4) comprises a rotating vertical upright (43) and at least one arm (44, 45) fixed to said rotating vertical upright (43). A vertical floating element (5) is rotatably fixed to the at least one arm (44, 45). The device (100) further comprises groups of rectilinear bars (12a, 12b) consisting of at least one pair of rectilinear bars (12a, 12b) parallel to each other and placed slidingly side by side along respective external edges.

Claims

1. A guiding and calibration device for a blown plastic film, comprising a bearing structure which provides along circumference equidistant rotation fulcrums of rotating structures, each rotating structure comprises a rotating vertical upright and at least one arm fixed to the rotating vertical upright, a vertical floating element is rotatably fixed to the at least one arm, guide means for the blown plastic film are fixed to the vertical floating element, the rotating structures are connected to each other through motion synchronization devices operated by at least one motor, wherein the guiding and calibration device further comprises groups of rectilinear bars formed by at least one pair of rectilinear bars parallel to each other and which slide side by side along respective external edges of each pair of rectilinear bars, each pair of rectilinear bars being integrally fixed to respective adjacent vertical floating elements.

2. The guiding and calibration device according to claim 1, wherein the rectilinear bars of each pair of rectilinear bars are mutually slidingly constrained by at least one slider able to maintain the parallelism of the rectilinear bars during adjustment movement of opening and closing of the guiding and calibration device, between a maximum opening position and a minimum opening position.

3. The guiding and calibration device according to claim 2, wherein the rectilinear bars are longitudinally grooved.

4. The guiding and calibration device according to claim 1, wherein the rectilinear bars of each pair of rectilinear bars have respective hooked external edges associated with one another so as to allow the sliding of a rectilinear bar of each pair of rectilinear bars with respect to the other rectilinear bar of each pair of rectilinear bars.

5. The guiding and calibration device according to claim 1, wherein a rectilinear bar of each pair of rectilinear bars has an external edge with a loop in which slides a protrusion of an external edge of the other rectilinear bar of each pair of rectilinear bars.

6. The guiding and calibration device according to claim 1, wherein at least one rectilinear bar of each pair of rectilinear bars has a length greater than half the distance existing between two adjacent vertical floating elements when the guiding and calibration device is in a maximum opening position.

7. The guiding and calibration device according to claim 1, wherein the rectilinear bars are horizontal.

8. The guiding and calibration device according to claim 7, wherein a rectilinear bar of the pair of rectilinear bars slides over the other rectilinear bar of the same pair of rectilinear bars.

9. The guiding and calibration device according to claim 1, wherein there is provided a number of pairs of the rectilinear bars equal to at least half the number of the vertical floating elements.

10. The guiding and calibration device according to claim 1, wherein the at least one arm is provided with a first end to which the vertical floating element is rotatably fixed, and a second end integrally fixed to the rotating vertical upright.

Description

DESCRIPTION OF THE DRAWINGS

(1) These and other features of the present invention will become more apparent from the following detailed description of a practical embodiment thereof, shown by way of non-limiting example in the accompanying drawings, in which:

(2) FIG. 1 shows a perspective view of a device according to the present invention, with sliding bars according to a first embodiment;

(3) FIG. 2 shows a perspective view of a portion of the device, with sliding bars in a first position;

(4) FIG. 3 shows a perspective view of a portion of the device, with the sliding bars in a second position;

(5) FIG. 4 shows a top plan view of the device in maximum opening position of the device;

(6) FIG. 5 shows a top plan view of the device in intermediate opening position of the device;

(7) FIG. 6 shows a top plan view of the device in minimum opening position of the device;

(8) FIG. 7 shows a front view of sliding bars according to a second embodiment;

(9) FIG. 8 shows a front view of sliding bars according to a third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(10) FIG. 1 shows a guiding and calibration device 100 of blown plastic film (also referred to as a calibrator drum) in which a bearing structure comprises a pair of rings 1 spaced apart by columns 2. There may be polygonal structures in place of the rings 1.

(11) Such rings 1 accommodate equidistant rotation fulcrums 3 of rotating structures 4 along an ideal circumference.

(12) Each rotating structure 4 comprises a rotating vertical upright 43, an upper arm 44 and a lower arm 45.

(13) The upper arm 44 is fixed to the upper end of upright 43, and the lower arm 45 is fixed to the lower end of upright 43.

(14) Six rotating structures 4 are depicted in the present embodiment.

(15) A vertical floating element 5 is rotatably fixed to a first end 441, 451 of each pair of arms 44, 45.

(16) A second end 442, 452 of the arms 44, 45 is integral with upright 43.

(17) At least one vertical profile 6 capable of supporting guide means 7 of the extruded tubular film is fixed to the floating element 5. Alternatively, the guide means 7 may be directly fixed to the floating element 5.

(18) The guide means 7 in the present embodiment are two horizontal rollers conveniently fixed to the vertical profile 6. Alternatively, the guide means 7 may be friction pads, air-blades or others.

(19) Possible elements required for the proper treatment of the extruded film, for example, reading sensors, air blowing mouths, pollutant suction hoods, and others, may also be fixed to the vertical profile 6 or to the floating element 5.

(20) The rotating structures 4 are connected to one another through a pantograph system comprising levers 8 and rods 9 which synchronize the movement thereof, actuated by one or more motors 10.

(21) The floating elements 5 rotate with respect to a vertical axis passing through an upper pin 5a and a lower pin 5b.

(22) Device 100 further comprises pairs of rectilinear bars parallel to each other and placed slidingly side by side.

(23) Each pair of bars comprises a first bar 12a parallel to and placed slidingly by side of a second bar 12b.

(24) The bars 12a, 12b slide with respect to each other along respective external edges.

(25) The bars 12a, 12b have respective parallel and distinct longitudinal axes of symmetry along which they slide with respect to each other.

(26) The bars 12a, 12b are integrally fixed to adjacent floating elements 5 along the rings 1.

(27) The bars 12a, 12b are mutually slidingly constrained by at least one slider 13 which maintains the parallelism of the bars 12a, 12b during the entire adjustment movement of the opening/closing of device 100.

(28) The figures depict an embodiment with bars 12a, 12b longitudinally grooved and slidingly constrained by means of two sliders 13.

(29) The bars 12a, 12b are horizontal, and bar 12b slides over bar 12a.

(30) Each bar 12a, 12b has a length which is at least slightly greater than half the existing distance between two adjacent floating elements 5 when arranged at the maximum opening (FIG. 2).

(31) Alternatively, at least one bar 12a, 12b of the pair of bars 12a, 12b is longer than the other bar 12b, 12a of the same pair of bars 12a, 12b.

(32) In any case, each bar 12a, 12b is capable of sliding by the side of the other so that at least one bar 12a, 12b goes beyond the end of the other bar 12b, 12a fixed to the floating element 5, thus allowing the mechanical limits dictated by telescopic solutions to be overcome and thus allowing a broad range to be covered while limiting the overall volume of device 100.

(33) Three alternating pairs of floating elements 5 may be connected in the present embodiment, i.e. being equal in number to the number of the floating elements 5 divided by two, using less components and resulting in increased economic advantage.

(34) The number of pairs of bars 12a, 12b generally needs to be at least half the number of vertical floating elements 5.

(35) FIGS. 4 to 6 depict device 100 in three exemplary positions of maximum, intermediate and minimum opening.

(36) FIG. 7 shows a pair of bars 12a, 12b according to a second embodiment, with respective hooked external edges 121a, 121b associated with one another so as to allow the sliding of a bar 12a with respect to the other bar 12b. In this embodiment no cursor 13 is required.

(37) Advantageously the two bars 12a, 12b can be obtained by cutting a single bar: the two bars 12a, 12b are in fact the same but mounted with the opposite position so that the hooked external edges 121a, 121b can be slidably associated.

(38) FIG. 8 shows a pair of bars 12a, 12b according to a third embodiment, in which a bar 12a has an external edge with a loop 122a in which slides a protrusion 122b of an external edge of the other bar 12b. Also in this embodiment no cursor 13 is required.

(39) In operation, starting from the maximum opening position in FIG. 4, the activation of motor 10 allows the simultaneous clockwise rotation of the rotating structures 4.

(40) The arms 44, 45 rotate and with them the floating elements 5, which in turn rotate about the vertical axis passing through the pins 5a, 5b.

(41) The rollers 7 advantageously are kept horizontal and tangent to a same circumference C (FIG. 5) due to the relative sliding of the bars 12a, 12b which always remain parallel and free to slide over one another by means of the sliders 13.

(42) Continuing with the rotation, the minimum opening position (FIG. 6) is reached, in which circumference C has minimum radius. It is worth noting that the rollers 7 overlap one another in the position because they are fixed at various heights on the vertical profile 6.

(43) Alternatively, the bars 12a, 12b may not be horizontal, but always need to be kept parallel and freely sliding side by side along respective external edges.

(44) Device 100 according to the present invention achieves a more affordable type of construction as compared to the known types, with less components, less kinematic mechanisms and less need for maintenance.

(45) The correct installation of the bars 12a, 12b on the respective floating element 5 is facilitated by making the latter by means of an extruded section bar having inclined planes which are symmetrical to a directrix D passing through the center of circumference C.

(46) Groups of more than two bars 12a, 12b may alternatively be provided, fixed to two adjacent floating elements 5 placed slidingly side by side.

(47) For example, there may be a bar 12a fixed to a floating element 5, and two bars 12b fixed to the adjacent floating element 5. Bar 12a slides between the two bars 12b, thus achieving an equivalent technical advantage.

(48) Additionally, there may be another two bars 12a which slide by the side of the two bars 12b.

(49) A single arm or more than two arms may be provided in place of a pair of arms 44, 45 for each vertical upright 43.