Pellet machine with oleodynamic control extruder group

Abstract

 The invention concerns a wood pellet machine which comprises a treatment chamber, a rotating annular extruder turning in said chamber and having radial holes, and rotating pressure rollers positioned and operating at a tangent to the internal surface of the perforated extruder and wherein a pressure roller (12) is associated with said extruder and can be moved and positioned at least radially or also axially to the internal surface of the extruder by means of a remote controlled oleodynamic actuators.

Description

Field of the Invention

[0001] This invention concerns vertical, cylindrical extruder pellet machines in general with internal pressure rollers, and refers in particular to an extruder group for such machines.

State of the Technique

[0002] The machines taken into consideration here and used for pelletising wood, usually include a rotating annular extruder, having a large number of radial holes and pressing rollers, also turning, positioned and operating at a tangent to the inner surface of the perforated extruder.

[0003] The starting raw material to be made into pellets is forwarded and crushed between the pressure rollers and the inner surface of the extruder and forced, in this way, to be extruded through the holes in the die. The pressure rollers are usually knurled to increase the crushing action on the material to be extruded and to prevent the latter from slipping out of the pressure area. The resulting extruded material is sheared by means of fixed blades operating on the external surface of the extruder to form the pellets.

[0004] In the known pellet machines, the rotation of the extruder is powered by an external motor unit using a belt or pulley drive, which besides being extremely cumbersome is also noisy. Furthermore, there are two or more pressure rollers and adjustment of their position with reference to the extruder is always a problem.

Object of the Invention

[0005] The object of this invention is to resolve the problems of the pellet machines of the known technique, by using oleodynamic drive on the extruder and a single pressure roller with variable positioning and which can at least be adjustable radially with remote control to allow it to adapt to the internal surface of the extruder.

[0006] The advantage of the above is that the pellet machine with cylindrical extrusion is simpler, less cumbersome and not as noisy and can be easily adjusted to the pressure of the extrusion of the initial material so as to optimise on the machine operating capacity and productivity.

[0007] Furthermore, the pressure roller can also be set up for axial positioning, which offers the possibility of using an extruder on the same pellet machining with at least two work sessions and usable alternatively, depending on the material to be pelletised, by simply moving the pressure roller from one work section to another.

[0008] The object and the advantages mentioned above are achieved, in compliance with the invention, using an improved wood pellet machine according to at least claim 1, that is, comprising a treatment chamber, a rotating annular extruder turning in said chamber and provided with a plurality of radial holes, and rotating pressure rollers, positioned and operating at a tangent to the internal surface of the perforated extruder and characterised in that a pressure roller supported by a support is associated with said extruder which can be moved and which can be positioned radially to the internal surface of the extruder by means of an oleodynamic actuator fixed to a stationary part.

Brief description of the drawings

[0009] The invention will however become more evident in the continuation of this description made in reference to the enclosed exemplifying drawings, in which:

Fig.1 is a schematic lateral view of the extruder group; and

Fig. 2 is a front view of the extruder-pressure roller connection.

Detailed Description of the Invention

[0010] In said drawing 10 indicates generically the casing of a pellet machine supporting a annular extruder 11, that is cylindrical, at a horizontal axis, to which a pressure roller 12 is actively associated.

[0011] The extruder 11 is supported by two rings or flanges 13 and turns powered preferably by an oleodynamic motor 14. As is known, the extruder 11 is equipped with numerous radial holes - not shown - for extruding the initial material and is housed and operates in a chamber formed by the casing 10 and closed at the front by a door 15.

[0012] The pressure roller 12 is coordinated and interacts with the internal surface of the annular extruder 11 where the material to be pelletised arrives from an external source. Said roller has a knurled peripheral surface 16 and is assembled, by the use a bearing 17, on a relative shaft 18 parallel to the rotation axis of the extruder 11.

[0013] The shaft 18 of the pressure roller 12 is supported by a support 19 integrated with a piston 20 that is housed and slides in a corresponding oleodynamic cylinder 21 fixed the door 15. The piston and relative cylinder are oriented radially to the shaft 18 of the pressure roller 12, and when said roller is associated with the extruder 11 it is inside the extruder itself. Thanks to this type of assembly, the pressure roller 12 can be positioned radially to the internal surface of the extruder, approaching or moving away from it according to needs, simply by means of an external activation command of the oleodynamic cylinder.

[0014] The material to be pelletised is conveyed from the outside to the inside of the extruder, between the surface of the latter and the pressure roller, where an action is developed that pushes the material through the holes of the extruder, extruding it to form pellets.

[0015] In addition, the pressure roller 12 with its connected radial oleodynamic positioning system 20, 21 can be assembled on a guided plate parallel to the roller axis and moved by at least one cylinder 22. In this way and as stated above, it will be possible to set up an extruder with at least two parallel, side by side, work sections, and use one or the other work section by axially moving the pressure roller from one work section to the other.

[0016] Worthy of mention is the fact that the supply of the material to the extruder of the machine is achieved by screw feed driven by a device with auto-adjusted rotating speed by an electronic and oleodynamic retroaction (Load-Sensing) and that the extruder can be associated with an automatic cleaning and lubricating system by an electro-oleodynamic control (Easy-Start).

Claims

1. A wood pellet machine, comprising a treatment chamber, a rotating annular extruder turning in said chamber and provided with radial holes, and rotating pressure rollers positioned and operating at a tangent to the internal surface of the perforated extruder, characterised by the fact that said annular extruder is associated with a pressure roller (12) supported by a movable support and which can be positioned radially to the internal surface of the extruder by means of an oleodynamic actuator fixed to a stationary part.

2. Pellet machine according to claim 1, wherein the pressure roller (12) has a shaft parallel to the rotating axis of the extruder, and wherein said shaft is supported by a by a support (19) integrated with a piston (20) housed and sliding in an oleodynamic cylinder (21) fixed to a closing door of the treatment chamber, said piston and relative cylinder being radially oriented to the shaft of said pressure roller (12).

3. Pellet machine according to claims 1 and 2, wherein the extruder has two different work sections placed side by side and wherein said pressure roller is movable and can be positioned axially in correlation with one or the other of said work sections of the extruder.

4. Pellet machine according to claim 3, wherein, for its axial positioning, said pressure roller (12) is assembled on a means of support movable by means of at least one oleodynamic cylinder.

5. Pellet machine according to any of the previous claims, wherein the rotating annular extruder is driven by an oleodynamic motor.

6. A wood pellet machine, comprising a treatment chamber, a rotating annular extruder turning in said chamber and having radial holes, and rotating pressure rollers positioned and operating at a tangent to the internal surface of the perforated extruder and characterised by the fact that a pressure roller (12) is associated with said extruder and can be moved and positioned both radially and axially to the internal surface of the extruder by means of a remote controlled oleodynamic actuator.

Drawing