WO2012016573A1

WO2012016573A1 - Guiding system for milling machine mouldboard designed to leave the milled material in a high layer on the milled surface

Info

Publication number: WO2012016573A1
Application number: PCT/EP2010/004738
Authority: WO
Inventors: Fabio Baldrati
Original assignee: Marini SpA
Current assignee: Marini SpA
Priority date: 2010-08-03
Filing date: 2010-08-03
Publication date: 2012-02-09
Anticipated expiration: 2013-02-03
Also published as: EP2601351A1; EP2601351B1

Abstract

Guiding system for milling machine mouldboard, in which the mouldboard (8) is raisable/lowerable and rotatable, the movement of the mouldboard (8) being guided by means of at least one cam-profile (16), which forces said mouldboard (8) to move for a certain stroke along sliding surfaces and a third surface of the cam-profile, the third surface defining the position of the stroke from which the rotation of the mouldboard begins; the guiding system further comprising at least one auxiliary block (18) comprising a by-pass surface of the third surface preventing the rotation of the mouldboard (8) and causing the mouldboard (8) to move in the vertical direction without starting to rotate, defining an extended raised position of the mouldboard (8) in which the flow of the milled material underneath the mouldboard (8) is allowed the scraping tools are in contact with the milled material and the access to the milling drum housing is prevented.

Description

DESCRIPTION

GUIDING SYSTEM FOR MILLING MACHINE MOULDBOARD DESIGNED TO LEAVE THE

MILLED MATERIAL IN A HIGH LAYER ON THE MILLED SURFACE

Technical field

The present invention concerns a guiding system for milling machine mouldboard designed to leave the milled material in a high layer on the milled surface and in particular for a milling machine for asphalt, concrete and other materials used for road pavings according to the characteristics of the pre-characterizing part of claim 1.

The present invention also concerns a milling machine provided with such guiding system according to the characteristics of the pre-characterizing part of claim 11.

Prior art

A road milling machine is a self-propelled machine, of known technology, finalized to the demolition of road pavings by means of milling with a rotating milling drum. A road milling machine (Figs. 1 , 2) is generally equipped with a milling drum (3) contained in a milling drum housing (7) opened downwardly to ensure the contact of said milling drum (3) with the surface to be milled and frontally opened for the outflow of the milled material outside the milling drum housing (7) itself.

The rear part of the milling drum housing (7) is closed by a rear mouldboard (8) generally made (Fig. 4) of an upper section (12) and of a lower section (13).

The upper section (12) is hinged at the hinging point (29) and it can rotate (Figs. 4,

6, 7, 8) around a horizontal axis, parallel to the rotating axis of the milling drum (3), the rotation being generally operated by two mouldboard operating pistons (24), which in the illustrated embodiment are two hydraulic pistons.

The lower section (13) slides over the upper section (12), being engaged to this by means (Fig. 3) of two slot guides (15). Moreover, the lower section (13) is also guided (Figs. 3, 4, 6, 7) by two cam-profiles (16) fitted on the first side wall (26) and second side wall (27) of the milling drum housing (7). Said cam-profiles (16) force the mouldboard lower section (13) to move vertically for a certain distance. Then the lower section (13) is disengaged from the lateral cam-profiles (16) and it rotates along with the upper section (12), both vertical and rotating movements being supported by said two mouldboard operating pistons (24).

The lower section (13) of the rear mouldboard (8) is provided with scraping tools (20) and it is generally in contact with the milled surface, being forced downwards by a controlled pressure of mouldboard operating pistons (24) and acting as a scraper to clean the milled surface.

The rear mouldboard (8) is generally opened, when the machine is stopped, to get the access to the milling tools for their replacement.

In normal milling operations the rear mouldboard (8) is in contact with the milled surface and contributes to transfer the milled material from the milling drum housing (7) onto (Figs. 1 , 2) a conveyor system (30), which in the illustrated embodiment comprises a collecting conveyor (5) and a loading conveyor (6).

In some works the milled material (23) must be left (Figs. 6, 7, 1 1) on the milled surface, for example for the so-called "in situ" recycling of the milled material (23). In this situation the normal operating practice consists of:

stopping the collecting conveyor (5) or, in general, the conveyor system (30); lifting the lower section (13) of the rear mouldboard (8) to such a height as to allow (Figs. 6, 7) the free flow of the milled material (23) underneath the rear mouldboard (8).

Problems of the prior art

In a prior art milling machine the vertical run of the lower section (13) of the rear mouldboard (8) is designed to leave an underneath clearance of about 200 mm. which allows the free flow of milled material (23) resulting from a milling depth of about 150 mm. or less. This represents a work limit, particularly in the "in situ" asphalt pavement recycling technology, where a milling depth of 200 mm. or more, is often required.

Moreover, in the prior art milling machines, when a milling depth higher than about

0

150 mm is required, it is necessary to fully rotate the rear mouldboard (8) upwards with the following disadvantages:

- possible access of the workers to a very dangerous area.

- inefficient containment of the milled material, which can be spread around by the milling drum (3) rotation.

Aim of the invention

The invention has the following aims:

to increase the vertical run of the lower section (13) of the rear mouldboard (8) as much as possible;

to allow a fast full opening of the rear mouldboard (8) up to an engagement safety position.

Advantageous effects of the invention

The solution according to the present invention presents many advantages, by the considerable creative contribution the effect of which constitutes an immediate and not negligible technical progress.

One of the advantageous effects of the present invention is due to the fact that the increasing of the vertical run of the lower section (13) is achieved by means of an adaption system which allows the use of the present invention also on the machines of the prior art.

Furthermore, with reference to the application to the prior art machines, the present invention does not require any modification of the design of the drum housing (7) Description of a preferred embodiment of the milling machine

An embodiment of the invention is now described with reference to the accompanying drawings in which:

Fig. 1 represents a side view of a milling machine.

Fig. 2 represents a side view of the milling machine of Fig. 1 , partially in section to show some of the internal components.

Fig.3 represents an overall view of a typical rear mouldboard according to the prior art. Fig. 4 represents a side sectional view of a typical rear mouldboard at one of the possible different opening stages.

Fig. 5 represents a side view of the cam-profile device of Fig. 4.

Fig. 6 represents a side sectional view of a typical rear mouldboard at one of the possible different opening stages.

Fig. 7 represents a side sectional view of a typical rear mouldboard at one of the possible different opening stages.

Fig. 8 represents a side sectional view of a typical rear mouldboard at one of the possible different opening stages.

Fig. 9 represents a side sectional view of the rear mouldboard according to the present invention at one of the possible different opening stages.

Fig. 10 represents a side view of the cam-profile device and of the auxiliary block of Fig. 9.

Fig. 11 represents a side sectional view of the rear mouldboard according to the present invention at one of the possible different opening stages.

Fig. 12 represents a view of one of the auxiliary blocks according to the present invention.

Fig. 13, 14, 15 represent side views illustrating the insertion of one of the auxiliary blocks of Fig. 12 according to the present invention.

Detailed description of the milling machine with reference to the drawings

Because of the deterioration of the road pavement due to atmospheric causes and to the traffic load, the periodical renewal of the same is necessary. For such renewal operation the removal of the old pavement is generally required.

The milling machines answer this need, being machines specially conceived for the removal of the old pavement before the laying of the new mat. The road milling machine (Figs. 1 , 2) consists of a self-propelled chassis (1) supported on tracks (2), or wheels, generally equipped with hydraulic drives that pull power from an engine, which is usually a diesel engine. The milling drum (3) is supported by the chassis (1), transversely to the advancement direction (14) of the machine and is activated by the engine through a mechanical transmission, or by a hydraulic transmission. The tracks (2), or wheels, are connected to telescopic columns (4), by means of which the chassis (1 ) is brought to height and set to obtain the correct milling profile. The material milled by the milling drum (3) is removed from the milling drum housing (7) by means of a conveyor system (30) consisting of one or two conveyors (5, 6) and it can be discharged at the forepart of the machine or at its back. In the first case the material is discharged on means of transportation that precedes the milling machine, while in the second case the means of transportation follows the milling machine proceeding in reverse motion.

The description of the invention refers to its application on a road milling machine with frontal charge of known technology (Figs. 1 , 2), in which the milling drum (3) is contained in a drum housing (7). Referring to the advancement direction (14) during operation, the drum housing (7) is provided with a movable rear mouldboard (8), provided with scraping tools (20) for the cleaning of the milled surface, and it is also provided with two movable side plates (9, 10) in contact with the road surface, with floating or slightly forced action.

However, it will be apparent to one skilled in the art that the invention, object of the present application, is also applicable to milling machines with rear discharging.

In the forepart of the milling drum housing (7) an opening (28) is provided (Fig. 2), which allows the discharging of the milled material onto a first conveyor belt, which is generally identified as the collecting conveyor (5). The rear part of said collecting conveyor (5) is supported by a device commonly known with the name of pressure bar (11 ), which is generally kept in a more or less forced contact condition with the surface to be milled, and the forepart of which slides on a support connected to the chassis (1) of the machine. The collecting conveyor (5) discharges the milled material onto a loading conveyor (6) which can be slewed vertically and horizontally to adapt its discharge head to the height and position of the transport vehicle, changing the position of the discharge point (25) with respect to the position of the chassis (1) of the machine. So, in general, the machine is equipped with a conveyor system (30) comprising at least one conveyor. The rear mouldboard (8) is divided (Fig. 3) into two sections, a lower section (13) and an upper section (12). The lower section (13) can be vertically moved and the upper section (12) can rotate (Figs. 4, 6, 7), along with the lower section (13), around a horizontal axis at a hinging point (29). The vertical movement of the lower section (13) allows maintaining the lower section (13) of the rear mouldboard (8) in contact with the milled surface with a floating or forced action, but for particular operative needs the rear mouldboard (8) may be also held partially raised to leave the milled material (23) flow below it.

The lower edge of the rear mouldboard (8) is provided with scraping tools (20) to clean the milled surface. The rotary motion around the hinging point (29) with a horizontal axis allows the total opening of the rear mouldboard (8) to access the tools of the milling drum (3) for their replacement.

The total opening/closing operation of the rear mouldboard (8) is performed by two mouldboard operating pistons (24) which are arranged in a parallel way. It will be apparent that depending on the dimensions of the rear mouldboard (8) and on the particular application single central operating piston could be used, the solution with two operating pistons (24) being the preferred one. When the rear mouldboard (8) is in the fully opened condition, the rear mouldboard (8) can be secured in position (Fig. 8) by means of a hook (22) which can be engaged with a retainer (21).

The sequence of the opening phase of the rear mouldboard (8) occurs due to the combined action of:

- the vertical slot guides (15), which allow the lower section (13) to vertically slide over the upper section (12) in contact with the same;

- the lateral cam-profiles (16) kept in contact with some cursors (17), which are integral with the rear mouldboard (8) and which form the contact element sliding on said cam-profiles (16).

In the first stage (Fig. 9) of the opening phase the lateral cursors (17) slide against (Fig. 5) the first surface (31) and the second surface (32) of the cam-profiles (16) and the lower part (13) of the rear mouldboard (8) moves in a vertical direction. When cursors (17) start to slide over the third surface (33) of the cam-profile (16), both the lower section (13) and the upper section (12) of the rear mouldboard (8) start to rotate as a single piece (Fig. 7).

During the run of the cursor (17) over the first surface (31 ) and the second surface (32), the thrust of the milled material (23) against the mouldboard (8) is supported by the lateral cam-profiles (16), but this does not happen along the run on the third surface (33). In this stage the thrust of the milled material contributes to the full opening of the mouldboard.

In the traditional machine the vertical run of the rear mouldboard (8) is limited to about 200 mm. which gives enough clearance for the flow of milled material (23) resulting from a milling depth of about 150 mm. For higher milling depth it would be necessary to fully rotate the rear mouldboard (8) upwards with the following disadvantages:

possible access of the workers to a very dangerous area.

- inefficient containment of the milled material, which can be spread around by the drum rotation.

In practice for a safe work of the rear mouldboard (8), the scraping tools (20) should be kept in contact with the milled material (23) at any time.

The present invention (Figs. 9, 10, 11) has solved the above mentioned problems of the prior art machines. Special auxiliary blocks (18) are fitted to the first side wall (26) and to the second side wall (27) of the milling drum housing (7).

In the illustrated preferred embodiment (Fig. 12), the auxiliary blocks (18) are shaped as a right-angle triangularly shaped body in which the hypotenuse (Figs. 9, 10) essentially constitutes a by-pass fourth surface (34) which allows to by-pass the third surface (33) of the lateral cam-profiles (16) during the movement of the lower section (13) of the rear mouldboard (8). One of the right-angled sides of the right-angle triangularly shaped body of the auxiliary block (18) goes in an abutment condition with the third surface (33) of the lateral cam-profiles (16), contributing to the release of the force applied to the auxiliary blocks (18) by the lower section (13) through the cursor (17).

The by-pass fourth surface (34) of the auxiliary blocks (18) forms an extension of the second surfaces (32) preventing the cursors (17) from sliding on the third surface (33) and guiding the movement of the cursors (17) in a vertical direction, thus preventing the rear mouldboard (8) from rotating around the hinging point (29) and causing the rear mouldboard (8) to further move in the vertical direction without starting to rotate around the hinging point (29). In this way the vertical stroke of the rear mouldboard (8) is extended. Thus an increased flow of the milled material (23) under the scraping tools (20) is allowed when the cutting depth is about 200 mm. or more.

In this way the rear mouldboard (8) can be kept in a working position also when the cutting depth is about 200 mm. or more, thus preventing the possible access of the workers to a very dangerous area and avoiding the inefficient containment of the milled material, which, otherwise, could be spread around by the milling drum (3) rotation.

The auxiliary blocks (18) are connected to the first side wall (26) and to the second side wall (27) of the milling drum housing (7) by means of a quick fastening system (19), which allows the auxiliary blocks (18) to be rapidly and easily removed to restore the full rotation condition of the mouldboard (8) in order to allow the access to the milling drum housing (7) only in case safety conditions are ensured.

The auxiliary blocks (18) provide means to extend the stroke of the lower section (13) of the rear mouldboard (8), vertically extending the length of the lateral cam-profile guides (16).

The auxiliary blocks (18) are quickly removable to allow the full opening of the rear mouldboard (8) up to the engagement of the safety hook (22) with the retainer (21).

In the illustrated preferred embodiment (Fig. 12), the quick fastening system (19) consists of a spacer (40) supporting a head (39). Each of the auxiliary blocks (18) is provided with two spaced fastening systems (19).

On the first side wall (26) and on the second side wall (27) of the milling drum housing (7) a couple (Fig. 13) of corresponding slotted holes (36) is obtained, each of said slotted holes (36) consisting of an enlarged portion (37) and a slotted portion (38). The axis of the slotted portion (38) of one of the slotted holes (36) is parallel to the axis of the slotted portion (38) of the other one of the slotted holes (36) of said couple of slotted holes (36).

The auxiliary block (18) is placed (Fig. 14) in correspondence with said slotted holes (36), with the heads (39) of the quick fastening system (19), which are positioned in correspondence of the enlarged portion (37) of the corresponding slotted hole (36). After inserting each of the heads (39) into the corresponding enlarged portion (37), the auxiliary block (18) is pulled backward (in the direction indicated by the arrow in Fig. 14) causing the spacer (40) to be inserted and to slide along the slotted portion (38) until the head (39) is prevented to exit from the corresponding enlarged portion (37) of the slotted hole (36).

At this point (Fig. 15) the lower section (13) of the rear mouldboard (8) is raised (in the direction indicated by the arrow in Fig. 15): the cursor (17) is prevented to slide on the third surface (33) of the cam-profile (16) and it slides on the by-pass fourth surface (34) of the auxiliary blocks (18), blocking in position the auxiliary block (18) and preventing the rear mouldboard (8) from rotating around the hinging point (29). Thus the access to the milling drum housing (7) is prevented and the vertical stroke of the rear mouldboard (8) is extended maintaining a safe working condition even in the case of an increased cutting depth. The raising of the mouldboard (8) causes said mouldboard (8) to slide along the fourth surface (34) of the auxiliary block (18) blocking in position the auxiliary block (18) applied to the milling drum housing (7) by means of the couple of slotted holes (36). Thus the unblocking of the auxiliary block (18) is prevented by the mouldboard (8) itself, allowing to have a real fast mounting and demounting of the auxiliary blocks (18).

It will be apparent that the mouldboard (8) can be obtained in a single piece, without providing a lower section (13) and an upper section (12). The invention will be applicable also in the case of a single piece mouldboard (8). So, in general, the guiding system for milling machine mouldboard according to the present invention is applicable to any milling machine which is provided with a milling drum housing (7) defined at least by one first sidewall (26), one second sidewall (27) and said mouldboard (8). The invention can be advantageously applied also to existing milling machines provided with a mouldboard (8) which is raisable/lowerable and rotatable around a hinging point (29) with respect to the milling drum housing (7) by means of at least one operating piston (24) between:

- at least one lowered position in which scraping tools (20) applied on the lower end of the mouldboard (8) are in contact with the milled surface and in which the access to the milling drum housing (7) is prevented;

- at least one partially raised position in which the flow of the milled material (23) underneath the mouldboard (8) is allowed, the scraping tools (20) being in contact with the milled material flowing underneath the mouldboard (8) and in which the access to the milling drum housing (7) is prevented;

- a retracted raised position in which the mouldboard (8) is rotated allowing the access to the milling drum housing (7).

The raising/lowering movement of the mouldboard (8) is guided by means of at least one cam-profile (16) which is part of the guiding system, and which forces the mouldboard (8) to move for a certain stroke along the direction defined by sliding surfaces (31 , 32) and a third surface (33) of the at least one cam-profile (16).

At least one sliding surface (31 , 32) defines the portion of the stroke of the mouldboard (8) along which the mouldboard (8) is moved between the at least one lowered position in which the scraping tools (20) are in contact with the milled surface and the partially raised position in which the flow of the milled material (23) underneath the mouldboard (8) is allowed

The third surface (33) defines the position of the stroke of the mouldboard (8) from which the rotation of the mouldboard (8) begins to reach the retracted raised position in which the mouldboard (8) is rotated allowing the access to the milling drum housing (7). The guiding system comprises at least one auxiliary block (18) which can be positioned in correspondence of the at least one cam-profile (16). The auxiliary block (18) is provided with a fourth surface (34) which forms an extension of the sliding surfaces (32, 32) constituting a by-pass surface of the third surface (33) preventing the rotation of the mouldboard (8). The raising movement of the mouldboard (8) causes the mouldboard (8) to slide along the fourth surface (34) causing the mouldboard (8) to further move in the vertical direction without starting to rotate around the hinging point (29) extending the vertical stroke of the mouldboard (8). The extended vertical stroke of the mouldboard (8) defines an extended raised position of the mouldboard (8) in which the flow of the milled material (23) underneath the mouldboard (8) is allowed, said scraping tools (20) being in contact with the milled material flowing underneath said mouldboard (8) and in which the access to the milling drum housing (7) is prevented, allowing to keep the mouldboard (8) in a working position also when the cutting depth is about 200 mm. or more, thus preventing the possible access of the workers to a very dangerous area and avoiding the inefficient containment of the milled material, which, otherwise, could be spread around by the milling drum (3) rotation.

In the case in which the mouldboard (8) comprises an upper section (12) and a lower section (13), the lower section (13) is slidable for a certain stroke with respect to the upper section (12) along slot guides (15) obtained on the upper section (12) itself. The sliding of the lower section (13) corresponds to the raising/lowering movement of the mouldboard (8) between the at least one lowered position in which the scraping tools (20) are in contact with the milled surface and the at least one partially raised position in which the flow of the milled material (23) underneath the mouldboard (8) is allowed. The upper section (12) is rotatable around the hinging point (29) with respect to the milling drum housing (7) and the rotation of the upper section (12) corresponds to the at least one partially raised position in which the access to said milling drum housing (7) is allowed. In this case, the at least one cam-profile (16) of the guiding system forces the lower section (13) to move for a certain stroke along the direction defined by the sliding surfaces (31 , 32) and the third surface (33) of the at least one cam-profile (16): and the at least one sliding surface (31 , 32) defines the portion of the stroke of the lower section (13) along which the lower section (13) is moved between the at least one lowered position in which said scraping tools (20) are in contact with the milled surface and the partially raised position in which the flow of the milled material (23) underneath the mouldboard (8) is allowed. The third surface (33) defines the position of the stroke of the mouldboard (8) from which the rotation of the upper section (12) begins to reach the retracted raised position in which the mouldboard (8) is rotated allowing the access to the milling drum housing (7). The fourth surface (34) of the at least one auxiliary block (18) forms an extension of the sliding surfaces (32, 32) constituting a by-pass surface of the third surface (33) preventing the rotation of the upper section (12). The raising movement of the lower section (13) along the fourth surface (34) causes the lower section (13) to further move in the vertical direction without the rotation of the upper section (12), extending the vertical stroke of the lower section (13). The extended vertical stroke of the lower section (13) defines an extended raised position of the mouldboard (8) in which the flow of the milled material (23) underneath the mouldboard (8) is allowed, said scraping tools (20) being in contact with the milled material flowing underneath said mouldboard (8) and in which the access to the milling drum housing (7) is prevented, allowing to keep the mouldboard (8) in a working position also when the cutting depth is about 200 mm. or more, thus preventing the possible access of the workers to a very dangerous area and avoiding the inefficient containment of the milled material, which, otherwise, could be spread around by the milling drum (3) rotation.

In the preferred embodiment, the guiding system for milling machine mouldboard according to the present invention comprises:

- two cam-profiles (16), each of which is installed in correspondence of one of the first sidewall (26) and second sidewall (27);

- two auxiliary blocks (18), each of which can be positioned in correspondence of one of said cam-profiles (16). In general, the cam-profile (16) of the guiding system can be provided with more than one sliding surface (31 , 32). For example in the illustrated embodiment (Fig. 11 ) the cam-profile (16) of the guiding system is provided with a first surface (31) and a second surface (32) and said third surface (33). The first surface (31 ) and the second surface (32) form sliding surfaces (31 , 32) defining the portion of the stroke of the mouldboard (8) along which the mouldboard (8) is moved between the at least one lowered position in which the scraping tools (20) are in contact with the milled surface and the partially raised position in which the flow of the milled material (23) underneath the mouldboard (8) is allowed. The third surface (33) defines the position of the stroke of the mouldboard (8) from which the rotation of the mouldboard (8) begins to reach the retracted raised position in which the mouldboard (8) is rotated allowing the access to the milling drum housing (7). The sliding of the mouldboard (8) along the first surface (31) occurs in an essentially vertical direction without rotation of the mouldboard (8) around the hinging point (29). The sliding of the mouldboard (8) along the second surface (32) occurs in an essentially vertical direction with a slight rotation of the mouldboard (8) around the hinging point (29).

The description of this invention has been made with reference to the enclosed figures showing a preferred embodiment of the invention itself, but it is evident that many alterations, modifications and variations will be apparent to those skilled in the art in the light of the foregoing description. Thus, it should be understood that the invention is not limited by the foregoing description, but it embraces all such alterations, modifications and variations in accordance with the spirit and scope of the appended claims.

Used nomenclature

With reference to the identification numbers reported in the enclosed figures, the following nomenclature has been used:

1. Chassis

2. Track

3. Milling drum 4. Telescopic columns

5. Collecting conveyor

6. Loading conveyor

7. Milling drum housing

8. Rear mouldboard

9. First side plate

10. Second side plate

11. Pressure bar

12. Upper section

13. Lower section

14. Advancement direction

15. Slot guide

16. Cam-profile

17. Cursor

18. Auxiliary blocks

19. Quick fastening system

20. Scraping tools

21. Retainer

22. Hook

23. Milled material

24. Mouldboard operating pistons

25. Discharge point

26. First sidewall

27. Second sidewall

28. Opening

29. Hinge or hinging point

30. Conveyor system

31. First surface 32. Second surface

33. Third surface

34. Forth surface

35. Fifth surface 36. Slotted hole

37. Enlarged portion

38. Slotted portion

39. Head

40. Spacer

Claims

1. Guiding system for milling machine mouldboard, said milling machine being provided with a milling drum housing (7) defined at least by one first sidewall (26), one second sidewall (27) and said mouldboard (8), said mouldboard (8) being raisable/lowerable and rotatable around a hinging point (29) with respect to said milling drum housing (7) by means of at least one operating piston (24) between:

- at least one lowered position in which scraping tools (20) applied on the lower end of said mouldboard (8) are in contact with the milled surface and in which the access to said milling drum housing (7) is prevented;

- at least one partially raised position in which the flow of the milled material (23) underneath said mouldboard (8) is allowed, said scraping tools (20) being in contact with the milled material flowing underneath said mouldboard (8) and in which the access to said milling drum housing (7) is prevented;

- a retracted raised position in which said mouldboard (8) is rotated allowing the access to said milling drum housing (7);

said raising/lowering movement of said mouldboard (8) being guided by means of at least one cam-profile (16) of said guiding system, which forces said mouldboard (8) to move for a certain stroke along the direction defined by sliding surfaces (31 , 32) and a third surface (33) of said at least one cam-profile (16):

- at least one sliding surface (31 , 32) defining the portion of the stroke of said mouldboard (8) along which said mouldboard (8) is moved between said at least one lowered position in which said scraping tools (20) are in contact with the milled surface and said partially raised position in which the flow of the milled material (23) underneath said mouldboard (8) is allowed;

- said third surface (33) defining the position of the stroke of said mouldboard (8) from which the rotation of said mouldboard (8) begins to reach said retracted raised position in which said mouldboard (8) is rotated allowing the access to said milling drum housing (7); characterized in that said guiding system comprises at least one auxiliary block (18) which can be positioned in correspondence of said at least one cam-profile (16), said auxiliary block (18) being provided with a fourth surface (34) which forms an extension of said sliding surfaces (32, 32) constituting a by-pass surface of said third surface (33) preventing the rotation of said mouldboard (8), the raising movement of said mouldboard (8) causing said mouldboard (8) to slide along said fourth surface (34) causing said mouldboard (8) to further move in the vertical direction without starting to rotate around said hinging point (29) extending the vertical stroke of said mouldboard (8), said extended vertical stroke of said mouldboard (8) defining an extended raised position of said mouldboard (8) in which the flow of the milled material (23) underneath said mouldboard (8) is allowed, said scraping tools (20) being in contact with the milled material flowing underneath said mouldboard (8) and in which the access to said milling drum housing (7) is prevented.

2. Guiding system for milling machine mouldboard, according to the previous claim characterized in that said mouldboard (8) comprises an upper section (12) and a lower section (13):

- said lower section (13) being slidable for a certain stroke with respect to said upper section (12) along slot guides (15) obtained on said upper section (12), the sliding of said lower section (13) corresponding to said raising/lowering movement of said mouldboard (8) between said at least one lowered position in which said scraping tools (20) are in contact with the milled surface and said at least one partially raised position in which the flow of the milled material (23) underneath said mouldboard (8) is allowed;

- said upper section (12) being rotatable around said hinging point (29) with respect to said milling drum housing (7), the rotation of said upper section (12) corresponding to said at least one partially raised position in which the access to said milling drum housing (7) is allowed;

said at least one cam-profile (16) of said guiding system forcing said lower section (13) to move for a certain stroke along the direction defined by said sliding surfaces (31 , 32) and said third surface (33) of said at least one cam-profile (16):

- said at least one sliding surface (31 , 32) defining the portion of the stroke of said lower section (13), along which said lower section (13) is moved between said at least one lowered position in which said scraping tools (20) are in contact with the milled surface and said partially raised position in which the flow of the milled material (23) underneath said mouldboard (8) is allowed;

- said third surface (33) defining the position of the stroke of said mouldboard (8) from which the rotation of said upper section (12) begins to reach said retracted raised position in which said mouldboard (8) is rotated allowing the access to said milling drum housing (7)

said fourth surface (34) of said at least one auxiliary block (18) forming an extension of said sliding surfaces (32, 32) constituting a by-pass surface of said third surface (33) preventing the rotation of said upper section (12), the raising movement of said lower section (13) along said fourth surface (34) causing said lower section (13) to further move in the vertical direction without the rotation of said upper section (12), extending the vertical stroke of the said lower section (13).

3. Guiding system for milling machine mouldboard, according to any of previous claims 1 to 2 characterized in that said guiding system comprises at least one cursor (17) for each of said cam-profiles (16), said cursor (17) being integral with said mouldboard (8) and forming the contact element of said mouldboard (8) which slides on said at least one cam- profile (16).

4. Guiding system for milling machine mouldboard, according to any of previous claims 1 to 3 characterized in that it comprises:

- two of said cam-profiles (16), each of which is installed in correspondence of one of said first sidewall (26) and second sidewall (27);

- two of said auxiliary blocks (18), each of which can be positioned in correspondence of one of said cam-profiles (16).

5. Guiding system for milling machine mouldboard, according to any of previous claims 1 to 4 characterized in that said guiding system comprises a couple of slotted holes (36) obtained on said milling drum housing (7) for each of said auxiliary blocks (18), each of said slotted holes (36) consisting of an enlarged portion (37) and a slotted portion (38), the axis of the slotted portion (38) of one of said slotted holes (36) of said couple of said slotted holes (36) being parallel to the axis of the slotted portion (38) of the other one of said slotted holes (36) of said couple of said slotted holes (36), each of said auxiliary blocks (18) being provided with a quick fastening system (19) for each of said slotted holes (36), said quick fastening system (19) consisting of a spacer (40) supporting a head (39), said auxiliary block (18) being placed in correspondence with said slotted holes (36), said heads (39) of said quick fastening system (19) being positioned in correspondence of said enlarged portion (37) of the corresponding slotted hole (36), each of the heads (39) being inserted into the corresponding enlarged portion (37), the auxiliary block (18) being pulled in the direction of said slotted portion (38) causing said spacer (40) to be inserted and to slide along said slotted portion (38) until said head (39) is prevented to exit from the corresponding enlarged portion (37) of said slotted hole (36), the raising of said mouldboard (8) causing said mouldboard (8) to slide along said fourth surface (34) of said auxiliary block (18) blocking in position said auxiliary block (18) applied to said milling drum housing (7) by means of said couple of slotted holes (36).

6. Guiding system for milling machine mouldboard, according to the previous claim characterized in that said couple of slotted holes (36) obtained on said milling drum housing (7) for each of said auxiliary blocks (18), is obtained in correspondence of said sidewalls (26, 27) of said milling drum housing (7).

7. Guiding system for milling machine mouldboard, according to any of previous claims 1 to 6 characterized in that said auxiliary block (18) is shaped as a right-angle triangularly shaped body.

8. Guiding system for milling machine mouldboard, according to the previous claim characterized in that the hypotenuse of said right-angle triangularly shaped body essentially constitutes said by-pass fourth surface (34) which allows to by-pass said third surface (33) of said lateral cam-profiles (16).

9. Guiding system for milling machine mouldboard, according to any of previous claims 1 to 8 characterized in that said auxiliary block (18) is provided with a side going in an abutment condition with said third surface (33) of said lateral cam-profiles (16).

10. Guiding system for milling machine mouldboard, according to any of previous claims 1 to 9 characterized in that said cam-profile (16) is provided with a first surface (31) and a second surface (32) and said third surface (33), said first surface (31) and said second surface (32) forming sliding surfaces (31 , 32) defining the portion of the stroke of said mouldboard (8) along which said mouldboard (8) is moved between said least one lowered position in which said scraping tools (20) are in contact with the milled surface and said partially raised position in which the flow of the milled material (23) underneath said mouldboard (8) is allowed, said third surface (33) defining the position of the stroke of said mouldboard (8) from which the rotation of said mouldboard (8) begins to reach said retracted raised position in which said mouldboard (8) is rotated allowing the access to said milling drum housing (7), the sliding of said mouldboard (8) along said first surface (31) occurring in an essentially vertical direction without rotation of said mouldboard (8) around said hinging point (29), the sliding of said mouldboard (8) along said second surface (32) occurring in an essentially vertical direction with a slight rotation of said mouldboard (8) around said hinging point (29).

1 1. Milling machine characterized in that it is provided with a guiding system for mouldboard (8) according to any of previous claims 1 to 10.