GB2042606A

GB2042606A - A Process for Varying the Inclination of a Series of Threads with Respect to Another Series of Threads in an Element of Reticular Extruded Plastic Material Structure

Info

Publication number: GB2042606A
Application number: GB8003962A
Authority: GB
Original assignee: RDB SpA
Current assignee: RDB SpA
Priority date: 1979-02-28
Filing date: 1980-02-06
Publication date: 1980-09-24
Also published as: FR2453011B3; DE3005473A1; IT7920616A0; IT1110219B; FR2453011A1

Abstract

An extruded plastic net 1 of reticular structure is heated until a desired softening degree is attained; and a relative sliding or creeping of the opposing edges of the net 1 in accordance with the desired direction and amount of variation in the inclination of the longitudinal threads 2 of the net with respect to the transverse threads 3 to provide, for example, a square mesh structure of the net. The longitudinal edges of the net may be clamped between movable beds 4, 41 or held by continuous chains, Figs. 2 and 2A (both not shown). <IMAGE>

Description

SPECIFICATION A Process for Varying the Inclination of a Series of Threads with respect to Another Series of Threads in an Element of Reticular Extruded Plastic Material Structure This patent for industrial invention is concerned with a process for varying the inclination of a series of threads with respect to another series of threads in an element of reticular extruded plastic material structure.

Hereinafter, by the term "reticulated structure element" is is meant a net of plastic material provided by extrusion in continuous and tubular shape from a conventional extruding head and comprising a first series of parallel longitudinal threads and a second series of parallel transverse threads inclined with respect to said first series and by continuous cut along a pair of adjacent longitudinal threads to provide a continuous web in case then cut in a direction transversely of the longitudinal development in a plurality of sections of desired length.

The conventional technique for varying, after extrusion step, the inclination of a series of threads in an extruded reticulated structure element with respect to another series of threads enables the achievement of excellent results when the elementary threads comprising such an element have a comparatively reduced section, while not being feasible when said section exceeds such values as to form proportionally big link or connection knots.

It is of the present invention to provide a process enabling to vary as required and after extrusion step the inclination of a series of threads with respect to the other series independently of the section of such threads.

This and further objects of the invention will become evident to those skilled in the art from the reading of the following description and claims.

According to the invention, a process for varying the inclination of a series of threads with respect to the pattern of the other series of threads in an element of reticular extruded plastic material structure, said element comprising a first series of parallel longitudinal threads and a second series of parallel transverse threads inclined with respect to said first series, is essentially characterized by comprising the steps consisting of: (a) subjecting said element to heating until the desired softening degree is reached; and (b) causing a relative sliding or creeping of opposing edges of said element, said relative sliding or creeping being in accordance with the desired direction and rate or value of said variation in inclination of said threads of one series with respect to said threads of the other series.

In order that the invention be more clearly understood, some possible embodiments of the process will now be given with reference to the accompanying drawings, in which: Figs. 1 and 1 A schematically show the process as it can be batchwise carried out on net sections or lengths; and Figs. 2 and 2A schematically show the process as it can be continuously carried out on a net web W.

Referring to Figs. 1 and 1A, a net section or length 1, comprising longitudinal threads 2 and transverse threads 3 inclined by a value a with respect to threads 2, is anyhow clamped along its opposing edges between a pair of beds 4 and 4' which are relatively movable in the direction of arrows F and F'.

Suitable heating means, not shown, provide for causing said length or section 1 to attain the desired softening degree.

By causing an opposite displacement or movement of beds 4 and 4', in case combined with a relative spreading apart of the beds, the desired variation is caused of the angles a formed between said threads 2 and 3 until providing, for example, the square mesh structure shown in Fig.

1A.

The amount of opposite displacement or movement of beds (arrows F and F') will depend on the value of the desired variation in said angles a, duly taking into account the shrinkage or contraction forces normally present in reticular structures of plastic material.

In case of a continuous process on a net web, as shown in Figs. 2 and 2A, said web 5 will be mounted and clamped as conventional with its longitudinal edges on a pair of continuous chains 6 and 6' of differentiated feeding speed in the direction of arrows H. Also in this case a variation will be provided, of course after heating of said net, in the angles a between the longitudinal and transverse threads 2' and 3', respectively, will depend on the amount of the speed difference between said two chains 6 and 6'.

Fig. 2A shows an approach similar to that shown in Fig. 2, which is particularly suited when desiring to cause in addition to the relative sliding or creeping of the longitudinal edges also a stretching of the transverse threads 3'. In such a case, said chains 6 and 6' are arranged so as to spread apart in their feeding direction H.

Claims

1. A process for varying the inclination of a series of threads with respect to the pattern of the other series of threads in an extruded element of reticular structure, said element comprising a first series of parallel longitudinal threads and a second series of parallel transverse threads inclined with respect to said first series of threads, characterised by comprising the steps consisting of: (a) subjecting said element to heating until the desired softening degree is attained, and (b) causing a relative sliding or creeping of opposing edges of said element, said relative sliding or creeping being in accordance with the desired direction and amount of inclination of said threads of one series with respect to said threads of the other series.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A Process for Varying the Inclination of a Series of Threads with respect to Another Series of Threads in an Element of Reticular Extruded Plastic Material Structure This patent for industrial invention is concerned with a process for varying the inclination of a series of threads with respect to another series of threads in an element of reticular extruded plastic material structure. Hereinafter, by the term "reticulated structure element" is is meant a net of plastic material provided by extrusion in continuous and tubular shape from a conventional extruding head and comprising a first series of parallel longitudinal threads and a second series of parallel transverse threads inclined with respect to said first series and by continuous cut along a pair of adjacent longitudinal threads to provide a continuous web in case then cut in a direction transversely of the longitudinal development in a plurality of sections of desired length. The conventional technique for varying, after extrusion step, the inclination of a series of threads in an extruded reticulated structure element with respect to another series of threads enables the achievement of excellent results when the elementary threads comprising such an element have a comparatively reduced section, while not being feasible when said section exceeds such values as to form proportionally big link or connection knots. It is of the present invention to provide a process enabling to vary as required and after extrusion step the inclination of a series of threads with respect to the other series independently of the section of such threads. This and further objects of the invention will become evident to those skilled in the art from the reading of the following description and claims. According to the invention, a process for varying the inclination of a series of threads with respect to the pattern of the other series of threads in an element of reticular extruded plastic material structure, said element comprising a first series of parallel longitudinal threads and a second series of parallel transverse threads inclined with respect to said first series, is essentially characterized by comprising the steps consisting of: (a) subjecting said element to heating until the desired softening degree is reached; and (b) causing a relative sliding or creeping of opposing edges of said element, said relative sliding or creeping being in accordance with the desired direction and rate or value of said variation in inclination of said threads of one series with respect to said threads of the other series. In order that the invention be more clearly understood, some possible embodiments of the process will now be given with reference to the accompanying drawings, in which: Figs. 1 and 1 A schematically show the process as it can be batchwise carried out on net sections or lengths; and Figs. 2 and 2A schematically show the process as it can be continuously carried out on a net web W. Referring to Figs. 1 and 1A, a net section or length 1, comprising longitudinal threads 2 and transverse threads 3 inclined by a value a with respect to threads 2, is anyhow clamped along its opposing edges between a pair of beds 4 and 4' which are relatively movable in the direction of arrows F and F'. Suitable heating means, not shown, provide for causing said length or section 1 to attain the desired softening degree. By causing an opposite displacement or movement of beds 4 and 4', in case combined with a relative spreading apart of the beds, the desired variation is caused of the angles a formed between said threads 2 and 3 until providing, for example, the square mesh structure shown in Fig. 1A. The amount of opposite displacement or movement of beds (arrows F and F') will depend on the value of the desired variation in said angles a, duly taking into account the shrinkage or contraction forces normally present in reticular structures of plastic material. In case of a continuous process on a net web, as shown in Figs. 2 and 2A, said web 5 will be mounted and clamped as conventional with its longitudinal edges on a pair of continuous chains 6 and 6' of differentiated feeding speed in the direction of arrows H. Also in this case a variation will be provided, of course after heating of said net, in the angles a between the longitudinal and transverse threads 2' and 3', respectively, will depend on the amount of the speed difference between said two chains 6 and 6'. Fig. 2A shows an approach similar to that shown in Fig. 2, which is particularly suited when desiring to cause in addition to the relative sliding or creeping of the longitudinal edges also a stretching of the transverse threads 3'. In such a case, said chains 6 and 6' are arranged so as to spread apart in their feeding direction H. Claims

2. A process according to Claim 1, characterised in that said second step of relative sliding or creeping consists of subjecting opposing edges of said reticular structure element to differentiated traction or feeding in the direction of the series of threads parallel to said opposing edges.

3. A process according to Claim 1, characterised in that said relative sliding or creeping of the opposing edges is in the case combined with a conventional stretching step of the other series of threads.

4. A process substantially as described herein with reference to and as illustrated in.Figures 1 and 1 A of the accompanying drawings.

5. A process substantially as described herein with reference to and as illustrated in Figures 2 and 2A of the accompanying drawings.