This application is the National Phase of International Application PCT/IB2017/055659 filed Sep. 19, 2017 which designated the U.S.

This application claims priority to Italian Patent Application No. 102016000104716 filed Oct. 18, 2016, which application is incorporated by reference herein.

This invention relates to a machine for conditioning pipes made of thermoplastic material.

More specifically, this invention relates to a belling machine, that is, designed to form end bells in the pipes made of plastic material.

This invention also relates to a method for conditioning pipes made of thermoplastic material.

In the production of pipes made of thermoplastic material designed for making pipes for delivering and/or discharging fluids (used, for example, in building works, drainage networks, drinking water distribution networks and sewerage networks) belling machines are used for shaping an end portion of the pipes into the characteristic “bell” shape, which has a wider shape relative to the normal diameter of the pipe (the so-called “bell and spigot”) and serves to connect together in succession the pipes which form the conduit. An unshaped end of a pipe is normally inserted in the bell-shaped end of the pipe upstream or downstream in the conduit.

The belling machine, which are generally automatic, can be installed in an extrusion line and, in line, receive the pipes or pieces of cut pipe to be processed.

The majority of belling machines make the bell on the end of the pipe with the hot forming process. The belling machines are equipped with at least one oven for heating the end of the pipe to be shaped and forming equipment which, by using a suitable mould, forms the heated end of the pipe into the shape of a bell.

A widespread application is the shaping of the end of the pipe by moulding with a spindle, also called a pad (in particular in the case of uPVC pipes, that is to say, unplasticized polyvinyl chloride). The spindle, or pad, reproduces the internal shape of the bell to be formed. In order to form the end of the pipe in the shape of a bell, the pad is inserted inside the pipe at that end to be shaped.

Amongst the belling machines of the conventional type should be noted the type of belling machine illustrated in patent document EP 0 684 124, by the same Applicant as this invention.

The above-mentioned patent document describes the configuration of an automatic belling machine of significant interest for optimising the production process, as well being suitable for processing short pipes (up to 0.5 m, to which it should be added the length of the bell). Typically it consists of various stations where the pipe is transported to perform the various operational steps.

The first station receives the cut pipe along the extrusion line. In this station, by using a suitable positioning device, the pipe is moved longitudinally and separated from the pipe following it and then stopped in a precise position always aligned with the axis of extrusion.

From this station the pipe is then moved transversely to place it at the other processing stations.

Thus, more in detail, the pipe coming from the extrusion line and cut into pieces is then positioned in two heating stations and in a forming station which are placed side by side.

When the pipe is positioned in the first heating station, advantageously the oven of the latter advances, from an initial withdrawn position, towards the pipe until enclosing the end of the pipe to be heated inside it. At the end of the first heating process, the oven withdraws and the freed pipe is moved transversely and positioned in front of the second heating station, in which are carried out the same movements of the first heating station.

After the heating process, with the second oven withdrawn, the pipe is positioned at the forming station and then clamped and locked by clamps, before the forming spindle, advancing, penetrates the pipe. Together with the spindle, a forming chamber, made in different types, also as a function of the material of the pipe being processed, feeds towards the pipe.

More specifically, in the processing of pipes made of polypropylene (PP), which are typical used for drains of buildings, the forming of the bell is conveniently achieved with an apparatus illustrated, for example, in patent document EP 0 700 771 in the name of the same Applicant as this invention; in this apparatus the forming chamber comprises different elements: outer moulds (for forming the outer shape of the bell), inner pad (for shaping and calibrating the inner surface of the bell) and a flange sliding on the pad (for shaping the edge of the bell). The heating oven may also be made of different types as a function of the material of the pipe being processed. For the processing of PP pipes the ovens are normally of the external contact type, that is to say, consisting of metal clamps, with a semi-circular shape, which are heat-controlled, that are closed on the outer surface of the end portion of the pipe to form the bell.

When both the forming and the cooling of the bell have been completed, the forming chamber retracts and the pipe, freed from the respective clamp is moved transversely to be discharged outside the belling machine.

A convenient dividing of the heating process has been performed with the solution just described with the aim of optimising the timing of the treatment cycle.

In order to further increase the productivity of belling machines, multi-belling solutions have been adopted, that is to say, wherein the pipes, after the positioning station, can be picked up in groups of two or more pipes each. These groups of pipes are then moved simultaneously and simultaneously processed in stations for heating and forming-cooling the bell.

For reasons of size and complexity of the heating devices and forming moulds, this solution is normally used only for processing small diameter pipes, that is, usually with diameters of not greater than 160 mm.

In the belling machines prepared for multi-belling, the above-mentioned device for positioning the pipes, which has the purpose of transferring the pipes between the various processing stations, is therefore configured to manage not individual pipes but groups of pipes, for example groups of three pipes, as usually occurs for the smaller diameters, for example with diameter less than 125 mm.

The belling machines prepared for multi-belling, due to the multiplicity of devices designed to process simultaneously, in each station, each pipe of the group, have a considerable overall size, particularly in the direction transversal to the direction of extrusion.

More specifically, the increase in the proportionally greater overall size derives from the multiplication of the stations for forming the pipe, due to the fact that at the stations there is a widening of the shape of the pipe, due to the formation of the bell.

A excessive transversal size could making the machine difficult to transport and difficult to install in the extrusion line, thereby also making the marketing difficult.

Moreover, a high transversal extension of the machine involves the drawback of long paths for transferring the pipes from one station to the next, thereby adversely affecting the overall processing time/cycle.

The aim of this invention is to provide a belling machine and method which overcome the drawbacks of the prior art.

A further aim of this invention is to provide a machine for belling pipes made of thermoplastic material set up for multi-belling which allows for high production speeds.

These aims and others, which are more apparent in the description which follows, are achieved, in accordance with this invention, by a belling machine and a method for belling comprising the technical features described in one or more of the appended claims.

