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Title:
IMPROVED MILLING ELEMENT FOR MILLING DRUMS OF SCARIFIERES AND MILLING DRUM USING SAID MILLING ELEMENT
Document Type and Number:
WIPO Patent Application WO/2012/080821
Kind Code:
A1
Abstract:
The invention is a milling element (1; 20; 50) for milling drums (T) of ground surface scarifiers, comprising: a support (2; 22; 52) suited to be applied to the outside of the cylindrical core (A) of the drum (T) and provided with a housing (3; 21) that accommodates a tool holder (4; 23; 53); a milling tool (5) provided with a tang (5a) suited to be removably fitted in a hole (7) made in the tool holder (4; 23; 53); connection means (10) suited to removably connect the tool holder (4; 23; 53) to the support (2; 22; 52). The connection means comprise: two opposing surfaces (11, 12; 24, 25; 54, 61) that delimit the housing (3; 21) and converge towards each other and towards the bottom surface (6; 27) of the housing (3; 21), with which they are connected to define an essentially U-shaped profile for the housing (3; 21); two opposing counter surfaces (13, 14; 34, 35; 60, 62) created in the tool holder (4; 23; 53) that converge towards one end (8; 36) of the tool holder. Means (15, 16, 17, 18; 41, 42, 37, 38; 54; 60) for containing the tool holder (4; 23; 53) in the housing (3; 21) are also provided. Each surface (11, 12; 24, 25; 54, 61) is arranged against a corresponding counter surface (13, 14; 34, 35; 60, 62) when the tool holder (4; 23; 53) is fitted in the housing (3; 21) with its end (8; 36) facing the bottom surface (6; 27) of the housing.

Inventors:
GELAI LUCIANO (IT)
Application Number:
PCT/IB2011/003048
Publication Date:
June 21, 2012
Filing Date:
December 14, 2011
Export Citation:
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Assignee:
GELAI E CASTEGNARO S P A (IT)
GELAI LUCIANO (IT)
International Classes:
B28D1/18
Foreign References:
US4275929A1981-06-30
US4621871A1986-11-11
EP0025421A21981-03-18
US4337980A1982-07-06
US4006936A1977-02-08
EP0025421A21981-03-18
US4337980A1982-07-06
US4275929A1981-06-30
US4621871A1986-11-11
Attorney, Agent or Firm:
BONINI, Ercole (Corso Fogazzaro 8, Vicenza, IT)
Download PDF:
Claims:
CLAIMS

1) Milling element (1 ; 20; 50) for milling drums (T) of scarifiers for ground surfaces, comprising:

- a support (2; 22; 52) suited to be applied to the outside of the cylindrical core (A) of said drum (T) and provided with a housing (3; 21) suited to accommodate at least one tool holder (4; 23; 53);

- a milling tool (5) provided with a tang (5a) suited to be removably fitted in a hole (7) made in said tool holder (4; 23; 53) and with an active portion (5b) suited to come into contact with the ground surface to be scarified;

- connection means (10) suited to removably connect said tool holder (4; 23; 53) to said support (2; 22; 52),

characterized in that said connection means (10) comprise:

- two or more opposing surfaces (11 , 12; 24, 25; 54, 61) that delimit said housing (3; 21) and converge towards each other and towards the bottom surface (6; 27) of said housing (3; 21), with which they are connected in order to define an essentially U-shaped profile for said housing (3; 21);

- two or more opposing counter surfaces (13, 14; 34, 35; 60, 62) created in said tool holder (4; 23; 53) and convergent towards one end (8; 36) of said tool holder;

- container means (15, 16, 17, 18; 41 , 42, 37, 38; 54; 60) of said tool holder (4; 23; 53) in said housing (3; 21),

each one of said surfaces (11, 12; 24, 25; 54, 61) being suited to be arranged against the corresponding counter surface (13, 14; 34, 35; 60, 62) when said tool holder (4; 23; 53) is fitted in said housing (3; 21) by arranging the end (8; 36) of said tool holder (4; 23; 53) so that it faces said bottom surface (6; 27).

2) Milling element (1 ; 20; 50) according to claim 1), characterized in that said bottom surface (6; 27) comprises a flat area (6a) and a concave area (6b) that are connected with each other and with said surfaces (11, 12).

3) Milling element (20; 50) according to claim 1) or 2), characterized in that one of said surfaces (24; 54) is created in a core (26; 56) that projects from said bottom surface (27) of said housing (21) and the corresponding counter surface (34; 60) belongs to a seat (29; 59) accommodating said core (26; 56) and created in said tool holder (23; 53).

4) Milling element (20) according to claim 3), characterized in that said core (26) is a prismatic body (28) and said seat (29) housing it is a prismatic pocket (31) whose base defines said counter surface (34) on which the corresponding surface (24) constituted by the lower face of said prismatic body (28) rests.

5) Milling element (50) according to claim 3), characterized in that said core (56) is a cylindrical pin (58) and said seat (59) housing it is a circular hole (51) whose internal lateral surface defines said counter surface (60) on which the corresponding surface (54) constituted by the external lateral surface of said cylindrical pin (58) rests.

6) Milling element (1) according to claim 1) or 2), characterized in that said container means (15, 16) comprise shoulder edges (17, 18) belonging to said tool holder (4) that delimit said counter surfaces (13, 14) in order to define guide paths (13a, 14a) that house said support (2) when said tool holder (4) is fitted in said housing (3).

7) Milling element (20) according to claim 4), characterized in that said container means (41 , 42, 37, 38) comprise opposing side walls (41 , 42) of said prismatic pocket (31), among which side counter walls (37, 38) of said prismatic body (28) are housed when said tool holder (23) is fitted in said housing (21).

8) Milling element (50) according to claim 5), characterized in that said container means (54, 60) comprise the internal lateral counter surface (60) of said hole (51) made in said tool holder (53) and the external lateral surface (54) of said pin (58) created in said support (52).

9) Milling element (1 ; 20; 50) according to any of the preceding claims, characterized in that said surfaces (11 , 12; 24, 25; 54, 61) converge towards the bottom surface (6; 27) of said housing (3; 21) and together form an acute angle (a) whose amplitude is included between 1° and 7°.

10) Milling element (1; 20; 50) according to any of the preceding claims, characterized in that said counter surfaces (13, 14; 34, 35; 60, 62) converge towards one end (8; 36) of the tool holder and together form an acute angle (a) whose amplitude is included between 1° and 7°.

11) Milling element (1 ; 20; 50) according to claim 9) or 10), characterized in that the amplitude of said acute angle (a) is 4°.

12) Milling drum (T) for scarifiers, characterized in that it comprises a plurality of milling elements (1 ; 20; 50) according to any of the preceding claims.

Description:
IMPROVED MILLING ELEMENT FOR MILLING DRUMS OF SCARIFIERS

AND MILLING DRUM USING SAID MILLING ELEMENTS.

DESCRIPTION

The invention concerns an improved milling element for milling drums of scarifiers.

The invention also concerns a milling drum in which a plurality of said milling elements is used.

It is known that to remove ground surfaces and in particular the bitumen layer that covers roads and motorways special machines called scarifiers are used, which are equipped with a milling drum whose surface has a plurality of milling elements arranged so as to form one or more adjacent spirals.

The excavation takes place owing to the rotation of the drum, whose milling elements, while the machine advances, progressively break the ground surface into which they are driven.

In the known embodiments each milling element is constituted by several components comprising a support fixed to the outside of the cylindrical core of the milling drum, which is associated with a tool holder provided with a hole, generally a through hole, in which the tang of a milling tool is removably inserted.

The milling tool is available on the market and comprises a conical body rounded at the level of the vertex, provided with a supporting collar from which the tang departs so as to be inserted in the hole provided in the tool holder. The tang of the milling tool rotatingly fits in the corresponding hole provided in the tool holder with the interposition of an elastic pin suited to make the tool stable and at the same time allow it to rotate.

The known milling elements are differentiated from one another especially by the way in which the tool holder is connected to the supporting body.

According to the known embodiments, the tool holder is fixed to the supporting body by welding.

This fixing method, however, poses the drawback that it makes maintenance of the drum difficult and expensive when it is necessary to replace the tool holder. In fact, in addition to replacing the milling tool due to its natural wear, it is often necessary to replace also the tool holder, and in order to do that the operator needs to remove the weld using a disk grinding wheel, with the risk, furthermore, to damage also the supporting body. After removal, the operator has to use welding means again in order to install a new tool holder.

It can be understood that following this operation the new tool holder may not be positioned exactly in the same position where there was the tool holder that has been replaced.

In some cases, if the replacement operation involves a large number of milling elements, this may result in a change, compared to the original configuration, in the profile of the spiral according to which the milling elements are arranged on the drum.

In order to overcome these possible and recognized drawbacks, some embodiments are known, for example those described in documents EP 0 025 421 and US 4 337 980, in which the tool holder, in order to be made easier and quicker to remove, is fixed to the supporting body through removable mechanical means, for example pins, screws or bolts.

When maintenance is required, these removable fixing means guarantee easier removal operations of the tool holder only in theory, since in practice during excavation the screws and pins oxidize and encrustations accumulate on them, so much so that it often becomes difficult and sometimes impossible to remove them.

In other cases the fixing means cannot be removed because they are deformed due to impacts to which they were subjected during excavation.

Therefore, even the fixing operation with pins or screws does not guarantee easy and safe removal of the tool holder and if the situations described above occurred, it would still be necessary to intervene with the removal methods described above, with the drawbacks already illustrated.

Embodiments are also known, like, for example, those described in documents US 4 275 929 and US 4 621 871, in which, in order to allow the tool holder to be easily and quickly removed from the support, the tool holder is connected to the corresponding support through connection means having dovetail or prismatic profiles of various types.

These embodiments, however, do not guarantee easy and safe removal of the tool holder, either, since the coupling area between the tool holder and the support is always in contact with the ground being processed and the presence of undercuts facilitates the deposit of the material that is removed during excavation. This tends to lock the tool holder in the support and sometimes may even prevent it from being removed.

The present invention intends to provide a milling element that makes it possible to overcome all the drawbacks described above.

In particular, it is a first object of the invention to provide a milling element comprising a support and a tool holder housing a milling tool, wherein the tool holder can be coupled with the corresponding support in a removable and quick way, with no need to use fixing means such as screws, pins and the like. It is another object of the invention that the fixing means connecting the tool holder with the supporting body always allow them to be easily and quickly removed.

It is a further object of the invention to provide fixing means that guarantee that the parts making up the milling element are always assembled in the same position after the possible replacement of one of them.

The objects described above are achieved through the construction of a milling element whose characteristics are described in the main claim, to which the reader should refer.

Further characteristics of the invention are described in the dependent claims.

According to the invention, the milling element that is described here below is provided with fixing means of its component parts that are constituted by their surfaces in mutual contact, which are mutually connected through interference when the parts making up the milling element are coupled with each other.

The coupling essentially takes place when the tool holder is fitted into a housing obtained in the support and is caused by the friction that each surface created in the support generates against the corresponding counter surface created in the tool holder, thus preventing their separation.

When the tool holder is coupled to the support, the coupling area is protected from contact with the material that is removed during excavation and has no undercut areas.

This prevents the accumulation of deposits that may lock the tool holder into the support, or at least makes such accumulation difficult.

Disassembly is thus facilitated and is carried out through thrust means that are forced between the tool holder and the support in order to generate a force exceeding the friction force along the direction defined by the surfaces in mutual contact and in the direction opposite their coupling direction. In particular, the thrust means are inserted at the side of the tool holder and thus with orthogonal direction with respect to the coupling direction of the tool holder in the support, in a housing defined between the tool holder and the support, differently from what happens in the known art, according to which the extraction of the tool holder from the support is obtained by pushing the tool holder in the direction opposite the direction of coupling with the support, through the insertion of the thrust means in a hole made in the back of the support itself.

This means that, advantageously, in the milling elements of the invention the removal of the tool holder is easier and quicker compared to the milling elements of the known art, especially when the milling drum is installed on the scarifier, as the operator intervenes with the thrust means between the milling elements and not behind them, which is instead necessary with the milling elements of the known art.

Advantageously, the fact that the parts making up the milling element of the invention are easy and quick to remove ensures easier and quicker maintenance operations.

Still advantageously, the absence of removable fixing means that may be deformed or get seized up during use of the drum guarantees that the parts making up the milling element can always be removed.

Furthermore, advantageously, the construction costs of the milling drums are reduced, as there are no screws, pins or other fixing elements for the milling elements.

The objects and advantages described above will be highlighted in greater detail in the description of preferred embodiments of the milling element of the invention that are provided as indicative, non-limiting examples with reference to the enclosed drawings, wherein:

- Figure 1 shows an axonometric view of three milling elements of the invention arranged aligned with one another in the position they assume when they are applied to the milling drum;

- Figure 2 shows an exploded axonometric view of one of the milling elements shown in Figure 1 ;

- Figures 3.1 , 3.2, 3.3 and 3.4 show four different views of a part of the milling element shown in Figure 2;

- Figure 4 shows an enlarged view of the coupling between the two parts that make up the milling element of Figure 2;

- Figure 5 shows an axonometric view of three milling elements of a variant embodiment when applied to the milling drum;

- Figures 6.1 and 6.2 show two different exploded axonometric views of one of the milling elements of Figure 5;

- Figure 7 shows an exploded side view of the milling element of Figure 6.1 ;

- Figure 8 shows an axonometric view of three milling elements of another variant embodiment when applied to the milling drum;

- Figures 9.1 and 9.2 show two different exploded axonometric views of one of the milling elements of Figure 8;

- Figure 10 shows an exploded side view of the milling element of Figure 9.1. The milling element that is the subject of the invention is shown in Figures from 1 to 4, where it is indicated as a whole by 1.

It is suited to be applied to the milling drum T of scarifiers for the removal of ground surfaces which, as can be seen in Figure 1 , essentially consists of a cylindrical core A that is set rotating by power means belonging to the same scarifier.

As far as the milling element 1 is concerned, it can be observed that it comprises a support 2 that is applied to the outside of the cylindrical core A of the milling drum T and is provided with a housing 3 suited to accommodate a tool holder 4.

The tool holder 4 is in turn removably coupled with a milling tool 5 that, as shown in the figures, is provided with a tang 5a suited to be removably fitted in a hole 7 made in the tool holder 4, and an active portion 5b projecting from the hole 7 and suited to come into contact with the ground surface to be milled. Connection means, indicated as a whole by 10, make it possible to removably connect the tool holder 4 to the support 2.

According to the invention, the connection means 10 comprise:

- two opposing surfaces 11, 12 that delimit the housing 3 and converge towards each other and towards the bottom surface 6 of the housing 3, to which they are connected;

- two opposing counter surfaces 13, 14 created in the tool holder 4 and converging towards the end 8 of the tool holder 4;

- means 15, 16 for containing the tool holder 4 in the housing 3 provided in the support 2. Each one of the surfaces 11 , 12 is arranged so as to bear against the corresponding counter surface 13, 14 when the tool holder 4 is fitted in the housing 3 provided in the support 2.

Concerning in particular the housing 3, it can be observed that it has a U-shaped profile defined by the above mentioned opposing surfaces 11 , 12 that converge towards each other and towards the bottom surface 6 of the housing 3, to which they are connected.

The U-shaped profile of the housing 3, being without undercut areas, prevents encrustations from accumulating during excavation, as on the other hand happens with the known milling elements described in the documents mentioned above, in which there are dovetail or prismatic housings whose geometry generates undercut areas.

Furthermore, the U shape of the housing 3 protects the area where it is coupled with the tool holder 4 from contact with the ground that is removed during excavation.

It can also be observed that the bottom surface 6 of the housing 3 has a flat area 6a and a concave area 6b that are connected to each other and to the two surfaces 11 , 12.

In particular, the concave area 6b allows the insertion of the counteracting means, for example an extraction pin, to separate the tool holder 4 from the support 2, as will be better explained below.

The tool holder 4, as shown in the figures, features counter surfaces 13, 14 that are provided on opposite sides in the tool holder 4 and are suited to be coupled with the surfaces 11 , 12 of the housing 3.

Regarding the container means 15, 16 they comprise shoulder edges 17, 18 belonging to the tool holder 4 that are arranged at the sides of the counter surfaces 13, 14.

Even the counter surfaces 13, 14 converge towards the end 8 of the tool holder 4 and each one of them, being delimited by the corresponding shoulder edges 17, 18, defines a guide path 13a, 14a having essentially a U-shaped profile, which slidingly houses the support 2 when the tool holder 4 is inserted in the housing 3.

Regarding the surfaces 11 , 12 and the counter surfaces 13, 14 that converge respectively towards the bottom surface 6 of the housing 3 and the end 8 of the tool holder 4, it can be noticed, with particular reference to Figure 4, that their angle of convergence a has variable amplitude ranging between 1° and 7° and its amplitude is preferably 4°.

The surfaces 11 and 12 thus converge towards each other and towards the bottom surface 6, and therefore diverge towards the open area of the housing 3, and this makes the accumulation of impurities and deposits in the coupling area between the tool holder 4 and the support 2 even more difficult.

Said angle of convergence a must however be smaller than the friction angle between each surface 11, 12 and the corresponding counter surface 13, 14 in mutual contact, so that when the tool holder 4 is fitted into the housing 3 in the support 2, the mutual friction guarantees the stability of the coupling.

Thus, the friction generated between each surface and the corresponding counter surface ensures the stability of the tool holder 4 in the support 2 essentially producing a condition of engagement.

In this way the use of mechanical connection means such as pins, screws or bolts or equivalent means is avoided, thus achieving one of the objects of the invention.

The tool holder 4 can be removed from the corresponding support 2 easily and quickly, since it is sufficient to insert an extraction pin at the side of the tool holder 4, in the concave area 6b of the bottom surface 6 of the housing 3 and to force it against the end 8 of the tool holder 4.

In this way the separation of the tool holder 4 from the housing 3 that accommodates it takes place through a simple sliding movement along the guide paths 13a, 14a when the force generated along the surfaces and counter surfaces in mutual contact exceeds the friction force.

In particular, the insertion of the extraction pin or other thrust means in the concave area 6b, and therefore laterally between the support 2 and the tool holder 4, instead of at the back of the milling element as in the known art, facilitates the removal of the tool holder 4 when it is necessary to replace the milling tools 5, especially when the drum T is installed on the scarifier.

In practice, to make the milling element 1 once the corresponding support 2 has been applied to the cylindrical core A of the drum T, each tool holder 4 is inserted in the corresponding housing 3, making each surface 11 , 12 slide inside the guide path 13a, 14a of the tool holder 4.

In this way each surface 11, 12 is placed in contact with the corresponding counter surface 13, 14 and the converging profile of the surfaces and counter surfaces favours the engagement of the tool holder 4 in the support 2 even with no need to force the tool holder 4 excessively in the housing 3.

The invention thus achieves one of the objects of the invention, that is, the object to connect each tool holder 4 to the corresponding support 2 in a stable and safe manner, without using removable means such as pins, screws and the like.

This also brings the advantage that, since there are no such connection elements that can be deformed during use, each disassembly operation is easy and quick and is carried out by forcing an extraction pin between the end 8 of the tool holder 4 and the bottom surface 6 of the housing 3.

Furthermore, the absence of mechanical fixing means like pins, screws and the like also facilitates the operations of assembly of each tool holder 4 in the corresponding support 2 when a milling drum T has to be obtained.

A variant embodiment of the invention is shown in Figures from 5 to 7, where the milling element, indicated as a whole by 20, differs from the embodiment just described due to the fact that the housing 21 present in the support 22 that accommodates the tool holder 23 is defined by two opposing surfaces 24, 25, wherein the surface 24 is created in a core 26 projecting from the bottom surface 27 of the housing 21.

It can be observed, in particular, that said core 26 is a prismatic body 28 with shaped end, whose lower face constitutes the surface 24 that delimits the housing 21.

Regarding the tool holder 23, it can be observed that it has a seat 29 essentially defined by a prismatic pocket 31 that houses the prismatic body 28 when the tool holder 23 is coupled in the housing 21 provided in the support 22

In this embodiment the base of the pocket 31 makes up the counter surface 34 bearing against the corresponding surface 24 of the support 22, while the base of the tool holder 23 makes up the counter surface 35 bearing against the corresponding surface 25 of the support 22.

As shown in Figure 7, also in this variant embodiment the surfaces 24, 25 and the counter surfaces 34, 35 are opposite each other and converge respectively towards the bottom surface 27 of the housing 21 and the end 36 of the tool holder 23 with an angle a whose amplitude is preferably but not necessarily 4°. Even in this variant embodiment the value of this angle a may in any case range from 1° to 7°.

With particular reference to Figures 6.1 and 6.2, it can also be observed that the container means comprise the opposing side walls 41, 42 of the prismatic pocket 31, against which the side counter walls 37, 38 belonging to the prismatic body 28 rest when the tool holder 23 is fitted in the corresponding housing 21 and the prismatic body 28 is housed in the corresponding prismatic pocket 31.

Even the side walls 41 , 42 and the corresponding side counter walls 37, 38 are inclined with respect to each other and convergent according to angle a whose amplitude is preferably but not necessarily 4°.

In this way, also the insertion of the prismatic body 28 in the corresponding prismatic pocket 31 favours the stability of the coupling of the tool holder 23 in the support 22 due to friction.

A further variant embodiment is illustrated in Figures from 8 to 10, in which it can be observed that the milling element, indicated as a whole by 50, differs from the variant embodiment just described in that the projecting core 56 of the support 52 and the seat 59 that houses it, provided in the tool holder 53, have a different shape.

In fact, it can be observed that the projecting core 56 is a cylindrical pin 58 while the seat 59 that houses it is a circular hole 51, wherein the external lateral surface of the pin 58 constitutes the surface 54 of the support 52 while the internal lateral surface 57 of the hole 51 is the corresponding counter surface 60 of the tool holder 53.

It should also be observed that in this case the container means are constituted by the same surface 54 and counter surface 60 respectively of the pin 58 and the hole 51, which thus serve the double function of container elements and sliding surfaces for the coupling and engagement of the tool holder 53 in the support 52.

Regarding the pin 58, this can be made in a single piece with the support 52 or it can be applied to it, for example through a screw connection.

Independently of whether the pin 58 is made in a single piece with the support 52 or is applied to it, its longitudinal axis Y is inclined by an angle a equal to 4° with respect to the corresponding opposing surface 61 created in the support 52.

Furthermore, also the axis Y' of the circular hole 51 is inclined by the same angle with respect to the counter surface 62 that constitutes the base of the tool holder 53.

Even in this variant embodiment the angle a may in any case range from 1 ° to 7°.

On the basis of the above description, it can be seen that the milling element of the invention, in all the variant embodiments described, achieves the set objects.

In particular, the invention achieves the object to completely eliminate the fixing means such as screws, pins and the like, which, besides making the assembly of each milling element difficult, make it difficult also to remove it when, for reasons due to usage, said fixing elements should be deformed or get seized due to encrustations or oxidation.

Furthermore, advantageously, the use of the milling element of the invention allows easy replacement of its components, always guaranteeing the arrangement of the components in the same position and thus ensuring that the helical profile according to which the milling elements are arranged on the drum is constant.

This ensures constant and homogeneous performance of the milling drum over time.

Furthermore, to advantage, the invention also achieves the object to avoid the need to intervene with special processing like grinding and welding in order to carry out maintenance and to replace the parts that make up the milling element.

Finally, the assembly operations of a milling drum starting from the application of the supports to the cylindrical core are facilitated and accelerated.

During construction of the milling element that is the subject of the invention modifications or variants not described herein and not illustrated in the figures may be carried out, which may consist, for example, in different shapes of the elements that make it up.

Said construction variants or modifications must all be considered protected by the present patent, provided that they fall within the scope of the claims expressed below.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the protection of each element identified by way of example by such reference signs.