In molding machines for polystyrene elements, molding is obtained through granule sintering with steam. Steam is introduced in the chamber with suitable pressure and temperature and transfers its energy to the polystyrene granules that increase in volume, thus realizing peripheral microcasting.

Microcasting reciprocally binds the granules until an object having the shape and size of the chamber generated by the two die halves is obtained.

By transferring energy to polystyrene, steam changes its physical state and turns into water, creating condensation.

The purpose of the present invention is to overcome the problems related to the current feed systems of process fluids, that is steam, water and air].

The machines that are currently available on the market show that steam feed towards the molding chamber is obtained in two different sections of the installation. The first section with rigid pipes serves the fixed die half, and the second section with rigid and flexible pipes serves the moving die half.

The same considerations can be made for the drainage circuits of condensate and other process fluids.

Typically, steam and air are introduced in the upper part of the mold, both in the fixed and moving part, while condensate is collecte in the lower part of the mold.

Therefore, the two circuits are different and placed in diametrically opposite position with respect to the horizontal axis of the mold.

This machine presents the following disadvantages and limitations : a) the need for separate installations for the various process fluids, resulting in an increase of industrial as well as maintenance and management costs ; b) pipes are present both on the upper part of the machine (steam, ejection air and vent) and the lower part of the machine (condensate evacuation and cooling vacuum), thus limiting the access to the machine and requiring more

space space; c) thermal non-homogeneity inside the molding chamber: going from up downward and transferring energy to the material to be molded, steams turns into water and condensate tends to accumulate in the lower part, creating a temperature gradient between this part and the upper part of the mold.

The purpose of the present invention is a molding machine for expanded polystyrene objects in which the pipes used for the introduction of steam inside the mold are inserted in the two die halves under their central horizontal axis, preferably on their lower horizontal edge; it being also provided that the pipes are also used to drain condensate, ejection air, vents and chamber vacuum, that is all of the process fluids.

A series of valves located on the fixed part of the machine and suitably actuated control the passage of the process fluids in the same pipe.

The main advantages of the invention are: a) elimination of the pipes on the top part of the machine, resulting in a considerable reduction in costs and space; b) uniform temperature distribution inside the mold ; once introduced inside the chamber, steam tends to rise; it transfers energy to the polystyrene granules and changes its physical state, turning into water; because of gravity, the small condensate water particles tend to descend towards the lower part of the mold, encountering steam with higher and higher energy ; the balance between these two phenomena inside the mold creates practically uniform temperature and humidity distribution conditions ; these conditions allow for molding objects with high physical and structural homogeneity.

The text continues with a detailed description of the operating principe of the present invention, with reference to drawings as per Figs. 1 to 4.

Figure 1 is a schematic lateral view of the machine according to the present invention, with the two die halves open.

Figure 2 is a front view of the moving die half with distribution header and feed pipe.

Figure 3 is a front view of the fixed die half with distribution header and feed pipe.

Figure 4 is a rear view of the machine showing valves and with headers.

The solution illustrated in the aforementioned figures is to be considered as a schematic representation of a purely illustrative, non-restrictive solution. The possibility of using the invention in other fields of application is not ruled out.

With reference to the aforementioned figures, the machine is basically composed of a frame or base (1), which represents its bearing structure, and two die halves, one fixed (2) and one moving (3). The union of the two die halves (2,3) generates the molding chamber for the polystyrene elements and is obtained by moving the moving die half (3) towards the fixed die half (2) along a generally horizontal direction.

The closing of the die halves includes two different steps: first, the moving die half (3) advances towards the fixed die half (2) until they touch and then the die halves are locked.

The fixed die half (2) is joined to the frame (1), while the moving die half (3) is connected to two lateral cylindrical bars (4) acting as support and slide guide.

The bars (4) joined to the moving die half (3) axially slide within a pair of ball bearings (5) fixed to the frame (1).

Once the two die halves have been locked, the polystyrene granules can be injected inside the chamber until they fill it.

The injection of steam inside the mold generates sintering or microcasting between the material granules. Microcasting reciprocally binds the granules until an object having the shape and size of the chamber generated by the two die halves is obtained.

With particular reference to the circuit of the moving die half (3), the circuit is composed of a series of valves (6) through which the fluid reaches the pipe (7). From here, by means of other flexible or telescopic pipes, it reaches the distribution header (9) that feeds some ducts with vertical axis (9a) inserted on the lower horizontal edge of the moving die half (3).

As regards the fixed die half (2), the circuit is composed of a series of valves (6') through which the fluid reaches the pipe (8) and from here the distribution header (10) that feeds some ducts with vertical axis (10a) inserted on the lower horizontal edge of the fixed die half (2).

Successively the same pipes are used for cooling, evacuating the condensate by means of vacuum.

Once molding has been completed, the two die halves are unlocked and the moving die half can be moved away in order to eject the molded object. This operation requires the introduction of air with pressure by means of the same pipe.

The cycle illustrated above can be operated in a cyclic mode.

By means of a control board, the operator carries out the management and control operations of the machine.

In summary, steam is introduced in the fixed (2) and moving die half (3) from the lower part by means of a single series of ducts (10a, 9a), which is also used to drain condensate, ejection air, vents and chamber vacuum, that is all of the process fluids. A series of valves located on the fixed part of the machine and suitably actuated control the passage of the process fluids in the same pipe.

The feed system of the process fluids illustrated above is a functional application that can be used in polystyrene molding regardless of the machine size and architecture. This description represents an applicative, non- limitative example.

The solutions described herein are merely illustrative and are to be considered as technically equivalent solutions that guarantee the maintenance of the operating principes as illustrated above.

The present invention can undergo numerous modifications and variations, all of them falling within the scope of the inventive concept. Moreover, all components can be replace with technically equivalent elements.

The object of the present invention can be subject to industrial application since the single components described herein are part of the state of the art.