IT201800004246A1 - Support with inclined faces for guiding means of a blown plastic film, for a guide and calibration device of the blown plastic film. - Google Patents

Description

DESCRIPTION

of the industrial invention entitled:

"Support with inclined faces for guiding means of a blown plastic film, for a guide and calibration device of the blown plastic film"

The present invention relates to a support with inclined faces for guiding means a of a blown plastic film, for a device for guiding and calibrating the blown plastic film.

In blown plastic film extrusion systems, a mass of molten plastic resin is continuously extracted from an annular die placed on the top of an extrusion head by means of a calender in turn placed on the top of said system and centered with respect to the vertical axis formed by the alignment of the center of the extrusion head with the midpoint of the calender rollers.

This tubular mass is blown from the inside to characterize it in the form of a thin tubular film, known in jargon as a "bubble", of defined dimensions and thicknesses.

This internal blowing is combined with a further cooling flow external to the tubular film in order to solidify the material and fix its physical and dimensional characteristics. This solidification zone is commonly identified as a frost line.

In this first section of the system, the tubular film in the formation phase is very delicate and subject to significant air turbulence, therefore requiring a device capable of accompanying its journey, containing oscillations and slips as well as helping to define its final dimensional characteristics. in concert with plant supervision sensors.

It is known in the art that these devices, called bubble guide calibrating baskets in jargon, are formed by one or more structures articulated to each other which simultaneously approach a plurality of guide means to the circumference of the tubular film in a tangential manner.

These guiding means, usually consisting of a plurality of rollers or sliding shoes or air blades, must be able to be adjusted to different diameters according to the size of the desired tubular film, and at the same time must provide a solid and reliable to the plurality of sensors that constantly monitor the dimensional parameters of the extruded product in order to promptly intercept any deviations from the set values and therefore provide the plant supervision system with the necessary feedback for the appropriate corrections. Such sensors, in order to provide correct measurements, must be arranged in such a way as to read the tubular film always in the radial direction, this always pointing towards the center of the circumference described by the film. According to the most common signal processing logics, the reading distance between the sensor and the film must always remain constant along the entire diameter adjustment range of the calibrator.

It is therefore easy to understand how the positioning and orientation accuracy of the guide means together with the rigidity of the entire calibration device are important factors for the final quality of the extruded product produced.

There are many types of such calibration devices, the main characterizations of which lie in the different system architectures designed for the adjustment along the horizontal (radial) axis of the guide means as a whole.

It is known from US-5441395 and EP-1714770 that on calibrators with perfectly radial movement (of the "scissor" type or equivalent) it is possible to increase the stabilization effect of the extruded tubular film by increasing the number of guide elements, while maintaining the the number of load-bearing structures, through the application of double opposing guide elements. In both the aforementioned embodiments, the guides are arranged in pairs by means of the same housing and specially prepared supporting structures.

Disadvantageously, said known calibrators do not provide for the possibility of a different configuration except to intervene heavily in the adaptation of the supporting structures.

The object of the present invention is to provide a support suitable for supporting guiding means of a plastic film in a bubble so that said guiding means can be configured in various ways.

A further object of the present invention is that said support can be easily coupled to movement synchronization means in known guiding and calibrating devices for a blown plastic film.

Still a further object of the present invention is that said support can be easily manufactured and coupled with known guide means.

In accordance with the invention said and further purposes are achieved by means of a support as defined in claim 1.

Advantageously, the guide means are fixed to the vertical floating element in a simple way with an economical support, without folds and / or angles.

The simplicity of the support of the guide means makes the configuration of the device particularly versatile as regards the choice of the guide means to be installed, their number and distribution in levels, both in the initial set-up phase and in any subsequent modification and / or update. in the field, bringing economy to the entire device and greater precision in installation.

The shape of the vertical profile together with the plates is independent of the way in which the radial orientation of the guide means is maintained.

These and other characteristics of the present invention will be made clearer by the following detailed description in an example of its practical embodiment illustrated by way of non-limiting purposes in the attached drawings, in which:

figure 1 shows a side view of a device with a support according to the present invention;

figure 2 shows a perspective view of the support;

Figure 3 shows a top plan view of the support with a guide means fixed to a first inclined grooved face;

Figure 4 shows a top plan view of the support with a second guide means fixed to a second inclined grooved face;

Figure 5 shows a top plan view of the support with the first and second guide means;

Figure 6 shows a partial top plan view of the device, which also shows an intermediate opening configuration;

Figure 7 shows a partial top plan view of the device, which also shows the intermediate opening configuration at a first level A; Figure 8 shows a partial top plan view of the device, which also shows the intermediate opening configuration at a second level B; Figure 9 shows a partial top plan view of the device, which also shows the configuration of intermediate opening at a third level C; Figure 10 shows a partial top plan view of the device, which also shows the intermediate opening configuration at a fourth level D; Figure 11 shows a top plan view of the support with a guide means fixed to a front grooved face.

Figure 1 shows a guiding and calibrating device 100 of blown plastic film (also called calibrating basket) in which a load-bearing structure comprises a pair of rings 1 spaced from columns 2. In place of the rings 1 there can be polygonal structures.

These rings 1 host, along an ideal circumference, equidistant rotation fulcrums 3 of rotating structures 4.

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

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

In the present embodiment, six rotating structures 4 are depicted.

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

A second end of the arms 44, 45 is integral with the upright 43.

At least one vertical profile 6 is fixed to the floating element 5 to support guide means 7 of the extruded tubular film.

In the present embodiment the guide means 7 are horizontal rollers fixed to the vertical profile 6 as will be clearer hereinafter. Alternatively, the guiding means 7 can be sliding shoes, air blades or the like

Any elements necessary for the correct treatment of the extruded film can also be fixed to the vertical profile 6 or to the floating element 5, for example reading sensors, air blowing openings, polluting suction hoods, and more.

The rotating structures 4 are connected to each other through a pantograph system comprising levers 8 and rods 9 which synchronize their movement, actuated by one or more motors 10.

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

Each floating element 5 has inclined planes 51, 52.

Said inclined planes 51, 52 develop vertically for the entire length of the floating element 5.

The device 100 further comprises pairs of straight push bars.

Each pair of bars comprises a first bar 12a and a second bar 12b, both solidly fixed to the same floating element 5 and forming an angle α between them equal to the internal angle existing between the sides of a regular polygon having a number of sides N equal to the number of floating elements 5, or α = [(1-2 / N) x 180 °].

Each bar 12a, 12b of each pair of bars 12a, 12b is integrally fixed to respective inclined planes 51, 52 of the same floating element 5.

Said inclined planes 51, 52 form the same angle α to each other as the bars 12a, 12b.

Each bar 12a, 12b has a length equal to at least the distance existing between two adjacent floating elements 5.

The bars 12a, 12b are preferably horizontal and are designed to rest on inclined planes 51, 52 of a floating element 5 adjacent to the floating element 5 to which they are fixed.

Preferably the bars 12a, 12b of each pair of bars 12a, 12b lie on the same horizontal plane.

In particular, the bar 12a is fixed to an inclined plane 51 of a floating element 5, and the bar 12b is fixed to an inclined plane 52 of the same floating element 5.

The bar 12a abuts against the inclined plane 52 of the floating element 5 adjacent to the right of the floating element 5, while the bar 12b abuts against the inclined plane 51 of the floating element 5 adjacent to the left of the floating element 5. Advantageously the bars 12a, 12b fastening to the floating element 5 push towards the center O of the device 100 (and of the circumference C) the floating elements 5 on which they rest slidingly.

Similarly, the adjacent floating elements 5 will have bars 12a, 12b fixed to them and able to push the adjacent floating element 5 because they rest on respective inclined planes 52, 51.

Obviously, to avoid unwanted contacts, the bars 12a, 12b fixed to the floating element 5 will be at different heights than the bars 12a, 12b fixed to the adjacent floating elements 5.

The bars 12a, 12b of each pair of bars 12a, 12b can be one piece with each other, or form a single section with two portions forming the angle α and fixed to a floating element 5 where said angle α is formed.

The vertical profile 6 comprises two inclined grooved faces 61, 62 to which plates 63 are separably associable, and a front grooved face 64.

A guide means 7 can be separably associated with each plate 63.

Figure 5 shows a vertical profile 6 in which the inclined grooved faces 61, 62 lie on planes inclined to each other by a fixed angle β equal to the ratio between the round angle and double the number N of the vertical profiles 6 of the device, that is β = 360 ° / (2N).

The plates 63 have the same inclination as said inclined grooved faces 61, 62 because they rest on them.

The same fixed angle β is formed by axes D of the guiding means 7 supported by the plates 63 fixed to the same vertical profile 6, because the guiding means 7, for example rollers, have an axis of rotation orthogonal to the plates 63 and tangent to C .

The axis D passes from the point of tangency of the guide means 7 to the circumference C, and from the center O of said circumference (and of the device 100).

An S axis passing through the vertical rotation axis of the floating element 5 and orthogonal to C, cuts the fixed angle β in two.

A guide means 7, for example a roller, with an axis of rotation orthogonal to the S axis is fixed to the front grooved face 64 by means of a further plate 63 (Figure 11).

The vertical profile 6 is fixed integral with the floating element 5 along a plane 65 orthogonal to said axis S.

Said plane 65 is coupled with a plane 53 of the floating element 5.

The plane 53 is also orthogonal to the S.

Figures 6-10 show an intermediate opening configuration with the guide means 7 associated with vertical profiles 6.

Figures 7-10 show guide means 7 with equidistant points of tangency on the circumference C of the extruded film in the intermediate opening position.

Advantageously, said equidistance, different in value, is maintained during the whole adjustment movement of the diameter of the device 100, from a maximum opening position to a minimum opening position.

Each guiding means 7 is arranged in such a way that, seen in plan view, it can be equated to the side of a regular polygon having a number of sides equal to the total number of guiding means 7.

The vertical profile 6 together with the plates 63 (and relative fixing means, such as screws, nuts and the like) defines a support for the guide means 7, in accordance with the present invention.

Advantageously, the guide means 7 are fixed to the floating element 5 in a simple way with an economical support, without folds and / or angles.

The embodiment shown in the figures provides six rotating structures 4, with four guide means 7 mounted on each vertical profile 6, two by two on differently inclined plates 63, or two by two parallel.

Figures 7-10 show detailed plan views of horizontal levels A, B, C, D: each level A, B, C, D provides three guide means 7 of three different floating elements 5 tangent to the same circumference C.

Said configuration, possibly variable, makes it possible to guarantee the device an adequate range of adjustment of the diameter by crossing the guide means 7 by overlapping without interference.

The simplicity of fixing the guide means 7 to the floating element 5, by means of the support described above, makes the configuration of the device 100 particularly versatile as regards the choice of the guide means 7 to be installed, their number and distribution in levels, both in the initial set-up phase and in any subsequent modification and / or updating in the field, bringing economy to the entire device 100 and greater precision in installation.

Advantageously, the implementation of any possible variation and / or improvement that may be necessary in order to accommodate the evolutionary needs of the extrusion process is encouraged.

The shape of the vertical profile 6 together with the plates 63 is independent of the way in which the radial orientation of the guide means 7 is maintained.

The claimed support can be associated with any type of guide and calibration device belonging to the family of devices with radial movement or orientation, for example "scissor", in which there is a need to keep the guide means tangent to the bubble film and equally spaced on the circumference.

Claims (7)

CLAIMS 1. Support for guiding means (7) of a blown plastic film, for a guiding and calibration device (100) of the blown plastic film, characterized by the fact of predicting a vertical profile (6) comprising two inclined grooved faces (61, 62) and plates (63) separably associated with said inclined grooved faces (61, 62), a guide means (7) is separably associated with each plate (63), in which the inclined grooved faces (61, 62) lie on planes inclined to each other by a fixed angle (β). Support according to claim 1, characterized in that the vertical profile (6) comprises a plane (65) orthogonal to an axis (S) passing through the center (O) of a circumference (C) of the blown plastic film. Support according to any one of the preceding claims, characterized in that the vertical profile (6) comprises a front grooved face (64). 4. Device for guiding and calibrating (100) a blown plastic film, comprising a supporting structure (1, 2) which provides, along an ideal circumference, equidistant rotation fulcrums (3) of rotating structures (4), 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 at least one arm (44, 45), guiding means (7) of the blown plastic film are fixed to the vertical floating element (5), the rotating structures (4) are connected to each other through motion synchronization means (8, 9, 12a, 12b) driven by at least one motor (10), characterized by the fact that a support for guiding means (7) according to any one of the preceding claims is rigidly fixed to each vertical floating element (5), said fixed angle (β) being equal to the ratio between the round angle and double the number (N) of the vertical profiles (6) of the device (100). 5. Device (100) according to claim 4, characterized in that the axis (S) passing through the center (O) of a circumference (C) of the blown plastic film, intersects the vertical axis of rotation of the element vertical float (5). 6. Device (100) according to claim 4 or 5, characterized in that said plane (65) of the vertical profile (6) is coupled with a plane (53) of the vertical floating element (5). Device (100) according to any one of claims 4-6, characterized in that the guide means (7) are rollers.