TOOL, TOOLHOLDER AND TOOL-TOOLHOLDER UNIT FOR MILLING CUTTERS AND/OR SHREDDERS

DESCRIPTION

The present invention refers in general to a tool, a toolholder and a tool- toolholder unit.

More particularly, it refers to a tool, a toolholder and a tool-toolholder carried out by joining said tool to said toolholder through coupling means so as to obtain a stable and durable fixing of both elements to be mounted on cutters or shredders, their fixing being releasable.

As is known, the milling cutters, the shredders or other machines for the crushing and chopping can comprise one or more rotors to which toolholders are fixed stably; in turn, a corresponding tool comprising one or more cutting elements is coupled to each toolholder.

The coupling system to join the tool to the toolholder must allow a stable, rigid fixing because the tool has to support heavy workloads and high opposing forces.

At the same time, the tool must be removable from the toolholder for a substitution with another tool or for the necessary maintenance, for instance for the substitution of the cutting elements worn.

Consequently, the coupling system for the joining of a tool to a toolholder must allow on the one hand a stable union to ensure an optimal action of the tool on the material to be chopped; on the other hand, this coupling system must allow a practical removal and a fast fixing between tool and toolholder so as to avoid a complication or slowdown of the routine maintenance operations. According to the prior art, a tool can be joined to its corresponding toolholder by means of a screw which is screwed into a first hole in the tool and into a second hole in the toolholder, both holes being coaxial. According to this configuration, the maintenance operation and the operation for the replacement of the tool are rather simple and fast since it is sufficient to unscrew just one screw for the removal of the tool from the toolholder. However, a coupling like this is not rigid and stable since the tool in action tends to slightly shift from the ideal position on rotating about an axis that is coaxial to the axis of the fixing screw, which involves a worsening in the performance of the working tool. In order to avoid said shifting, it is necessary to put the tool under tension on the toolholder through an interaction of inclined planes abutting against each other, said inclined planes being obtained on the tool and the toolholder, respectively; however, this configuration involves the creation of tensions in the fixing screw, as well so that the fixing screw is subjected to breakages.

In addition to the shifting due to the rotation, there is a vertical force due to the impacts against obstacles in the ground which tend to cause the detachment of the tool from the toolholder. This force acting on the vertex of the cutting element on the tool causes a moment that in turn causes a traction effort on the screw.

In order to avoid said problems, couplings are used such as those described in WO 2008/143891 which discloses the fixing of a tool to the toolholder through the action of two distinct screws which are screwed into two holes obtained in the tool and the toolholder, respectively.

A coupling of this typology makes the fixing of the tool to the toolholder more stable but makes the removal operation and the maintenance operations more complex and slower.

An aim of the invention is to remove the above mentioned drawbacks and further ones by carrying out a tool, a toolholder and a corresponding tool- toolholder unit comprising said tool and toolholder, for milling cutters, shedders or other mincing machines provided with an optimal coupling system of tool and toolholder.

Another aim of the invention is to carry out a coupling system which provides a stable, rigid fixing of the tool to the toolholder and at the same time, this coupling system allows, in case of need, a removal and a union of the two elements in a simple and quick way.

Another aim of the invention is to carry out a coupling system in which no unwished shifting of the tool is provoked relative to the toolholder when the tool is working.

Another aim of the invention is to obtain a coupling between tool and toolholder which does not put the two elements under tension so as to avoid breakages.

Another aim of the invention is to carry out a component in the coupling system which does not need to be substituted at any tool change with a consequent reduction of the maintenance costs.

Another aim of the invention is to carry out a safe tool-toolholder unit in which the screw or other equivalent element is not the only actual element keeping the two components united.

The above aims and other ones are achieved according to the invention by a tool-toolholder unit adapted to be fixed on a rotor of a mincing machine and comprising a toolholder and a tool; the toolholder comprises a first face, a second face and a surface portion adapted to fix the toolholder on the rotor, a first through- hole being obtained in said toolholder and being opened towards the first face; the tool comprises a third face and a fourth face which are arranged adjacent to said first face and to said second face of the toolholder when the tool is coupled to the tool holder, a second threaded hole being obtained in said tool, being opened at least towards the third face and being arranged coaxial to the first hole when the tool is coupled to the toolholder. The tool-toolholder unit is characterized by the fact that the toolholder comprises an element in relief which protrudes from the second face and that an opening is obtained in the tool, is opened towards the fourth face and is adapted to receive the element in relief when the tool is coupled to the toolholder, the width of the opening of the tool being equal to the width of the element in relief so as to prevent the tool from rotating in respect to the toolholder, a screw being received in the first hole and being screwed in the second hole so as to fix the tool and the toolholder on each other.

Consequently, although the tool is connected to the toolholder only by means of an only screw, the tool can not rotate about the axis of said screw since the element in relief, received in the opening obtained in the upper portion of the tool, prevents any slightest movement of rotation.

Advantageously, the tool can comprise a cylindrical body which protrudes from the third face and in which a second threaded hole is obtained, said cylindrical body being received in the first hole when the tool is coupled to the toolholder. In this way, the assembly operations are improved and the movements between tool and toolholder are reduced.

Besides, a third through-hole can be obtained in the tool and is adapted to receive a bush which comprises a cylindrical body in which the second threaded hole is obtained. In other terms, the cylindrical body can correspond to a portion of a bush which is received in a hole obtained in the tool. Consequently, after placing the tool at the side of the toolholder, the tool-toolholder unit is carried out by inserting the bush in the third through-hole of the tool so that the cylindrical body of the bush can be inserted in the through-hole of the toolholder. Through the presence of the bush, the screw is not the only element that makes the coupling safe although it is a fundamental element to provide a durable fixing. Indeed, even in case the screw should break, the threaded bush would be kept under pressure by the front impacts and would provide, together with the upper element in relief or the cylindrical body, the fixing of the tool to the toolholder at least for a short period.

Advantageously, in addition to the cylindrical body, the bush can comprise a head having a section of bigger dimensions than the cylindrical body and the third through-hole obtained in the tool can be formed by a fourth hole and a fifth hole having a shape homologous to the bush head so that the bush head can enter the fifth hole stably.

In particular, the bush head and the fifth hole can have a non-circular section so that a rotation of the bush head in the fifth hole is not possible.

Advantageously, the element in relief can be a pin which is received in a cavity which is obtained in the second face of the toolholder and the opening obtained in the tool can be a hole obtained in a protruding sector of the tool so that the pin can be received in said hole.

In this way, in order to obtain a tool-toolholder unit according to the invention it is sufficient to make a hole even in conventional toolholders and insert a pin in the hole. Besides, the opening obtained in the tool can be obtained in a protruding sector of the tool and can be open towards the free end of said protruding sector. In this way, the coupling of the tool with the toolholder is also carried out by putting the tool to the side of the toolholder so that the pin is inserted in the tool through the portion of the opening opened towards the free end.

According to the invention, the aims are also reached by a toolholder which is adapted to be fixed on a rotor of a mincing machine and to which a tool is coupled; the toolholder comprises a first face, a second face and a surface portion adapted to fix the toolholder on the rotor, a first through-hole is obtained in the toolholder and is opened towards the first face; said first face and said second face are adapted to be arranged adjacent to a third face and a fourth face of the tool, respectively, in which a second threaded hole is obtained; said first hole being coaxial to the second hole when the tool is coupled to the toolholder. The toolholder is characterized by the fact of comprising an element in relief which protrudes from the second face and is adapted to be received in an opening which is obtained in the fourth face of the tool and is opened towards the fourth face when the tool is coupled to the toolholder, the width of the opening of the tool being equal to the width of the element in relief so as to prevent the tool from rotating in respect to the toolholder.

According to the invention, the aims are also reached by a tool to be coupled to a toolholder, in which a first through-hole is obtained and which comprises a first face and a second face, said tool comprising a third face and a fourth face which are adapted to abut against said first face and said second face, respectively, for the coupling of the tool to the toolholder, a second hole being obtained in said tool and being arranged coaxial to the first hole when the tool is coupled to the toolholder. The tool is characterized by the fact that an opening is obtained in said tool towards the fourth face and is adapted to receive an element in relief which protrudes from the second face of the tool when the tool is coupled to the toolholder.

Further features and details of the invention will be better understood from the following description which is provided as a non-limiting example as well as from the accompanying drawings wherein:

Fig. 1 is a front view of a toolholder according to the invention;

Fig. 2 is a sectional side view of the toolholder in figure 1 according to plane A-A in figure 1 ;

Fig. 3 is a top view of the toolholder in figure 1 ;

Fig. 4 is a side view of a tool according to the invention;

Fig. 5 is a sectional side view of the tool in figure 4 according to the plane B-B in figure 6;

Figg. 6, 7 are front and bottom views of the tool in figure 4, respectively; Figg. 8, 9 are two schematic perspective views, namely, a side view and a rear view, of a bush, respectively;

Fig. 10 is a front view of the bush in figure 8;

Fig. 11 is a sectional side view of the bush in figure 8 according to plane C- C in figure 10;

Fig. 12 is a front view of a tool-toolholder unit according to the invention, formed by assembling the toolholder in figure 1 , the tool in figure 4 and the bush in figure 8;

Fig. 13 is a sectional side view of the tool-toolholder unit in figure 12 according to plane D-D in the same figure 12; Fig. 14 is a side perspective exploded view of the tool-toolholder unit in figure 12.

With reference to the accompanying figures, in particular figures 12, 13, 14, number 10 denotes a tool-toolholder unit adapted to be fixed on a rotor of a milling cutter, a shredder or other machine for the shredding and mincing and comprising a toolholder 12 and a tool 14 which are joined to each other by means of a pin, a bush 18, a screw 20 and a washer 22.

The toolholder 12 as represented separately in figures 1 to 3, comprises a steel body 24 which has two parallel side faces 26 and shows a profile having a perimeter with an essentially four-sided irregular shape, as it appears clearly from figure 2.

Indeed, the body 24 is laterally defined mainly by four side faces 28, 30, 32, 34 which are connected through connecting portions. In particular, the four faces are:

a first planar face 28,

a second planar face 30, inclined of about 95 degrees relative to the first face 28,

a side arched face 32, and

a lower face 34 showing an arched profile.

The toolholder 12 can be fixed rigidly to a rotor of a milling cutter or shredder through the union of the lower face 34 with a side surface of the rotor: the bending radius of the arched profile of the lower face 34 is indeed essentially equal to the radius of the rotor.

A through-hole is obtained in the body 24 and develops from the arched side face 32 to the first planar face 28; the hole is formed by three cylindrical coaxial holes having different diameters: a first hole 36 is open towards the first planar face 28, a second hole 38 is open towards the arched side face 32 and a third hole 40 connects the first hole 36 with the second hole 38. In particular, the diameter of the third hole 40 is shorter than the diameters of the first hole 36 and second hole 38, as visible in figure 2 so that a circular crown surface 39 is defined between the second hole 38 and the third hole 40.

Besides, a blind hole 42 is obtained in the upper part of the body 24, said blind hole being open towards the second planar face 30.

The tool 14 comprises a base steel body 44 in which a cutting element 45, made of a hard material, is set. The presence of the cutting element 45 allows objects such as stones, blocks of earth, wood, etc. to be minced or cut into little pieces through the action of the tool.

It is obvious that the tool, and in particular the cutting element, can be shaped in a manner different from the so-described tool/cutting element, the coupling features according to the invention being maintained.

A protruding sector 46 protrudes from a face of the base body 44 so as to define:

a third planar face 48 delimiting the base body 44 laterally,

a fourth planar face 50 delimiting the protruding sector 46 in the lower part and inclined of about 95 degrees relative to the third planar face 48;

a fifth planar face 52 delimiting the protruding sector 46 laterally and parallel to the third face 48.

A first through-hole 54 is obtained in the protruding sector 46 and develops with an axis that is parallel to the third face 48. The first through-hole 54 has a cylindrical shape and has a width L and a length M showing the same dimensions. In addition, a second through-hole having an axis orthogonal to the first through-hole 54 is obtained in the base body 44 and develops from the third face 48 to the front face of the tool, as represented in figure 5; the second through-hole is formed by two coaxial holes, of different shapes: a first cylindrical hole 56 is open towards the third planar face 48 and a second irregular hole 58 is open towards the front face of the tool. In particular, as it appears from figure 6, the second hole 58 has an irregular shape because it is defined by two planar surface portions 60 and two cylindrical surface portions 62 having a radius longer than the radius of the first hole 56 so that a circular crown surface 57 is defined between the first cylindrical hole 56 and the second irregular hole 58.

The bush 18, as represented in figures 8, 9, 10, 11 , is formed, in a single body, by a cylindrical body 64 and a head 66 which are coaxial to each other. The head 66 has an upper surface 68 which is inclined in respect to the axis of the head 66.

Besides, the head has a cross-section with irregular profile, which is homologous to that of the second hole 58 of the tool 14. Indeed, the side surface of the head 66 is formed by two planar surface portions 70 and two cylindrical surface portions 72 having a radius longer than the radius of the cylindrical body 64 so that a circular crown surface 65 is defined to connect the cylindrical body 64 to the head 66.

A threaded blind hole 73 is obtained in the bush 18 and is open towards the end of the cylindrical body 64 and is coaxial to the cylindrical body 64 and the head 66.

The screw 20 as represented in figure 14 comprises, in a single body, a threaded cylindrical body 74 and a cylindrical head 76 having a longer diameter than the first cylindrical body 74 so as to define a circular crown surface 75 between the cylindrical body 74 and the head 76.

A shaped cavity 77 visible in figure 13 is obtained in the head 76 and is for the screwing of the screw 20.

The toolholder 12 and the tool 14 can be joined together so as to obtain the tool-toolholder unit 10 according to the invention, as represented in figures 12, 13, 14.

The assembly of the two elements, as represented in particular in figure 14 is carried out by positioning at first the pin 16 in the blind hole 42 obtained in the toolholder 12. Since the height of the pin 16 exceeds the depth of the blind hole 42, the pin 16 protrudes in the upper part from the second planar face 30 of the toolholder 12.

Then, the tool 14 is placed adjacent to the toolholder 12 with a movement from top to bottom so that the protruding part of the pin 16 is inserted in the through-hole 54 in the tool 14.

The position of the blind hole 42 and consequently the position of the pin 16 in the toolholder 12 and the position of the through-hole 54 in the tool 14 are such that the joining of the tool to the toolholder causes also that the third face 48 and the fourth face 50 of the tool 14 abut against the first face 28 and the second face 30 of the toolholder 12, respectively.

In this position, as visible clearly in figure 13, the first cylindrical hole 56 and the second irregular hole 58, each being obtained in the tool 14, are coaxial to the first hole 36, second hole 38 and third hole 40 in the toolholder 12 so as to create an only through-hole that extends from the arched side face 32 of the toolholder 2 to the front face of the tool 14. In particular, the first cylindrical hole 56 of the tool 14 has the same diameter as the first hole 36 of the toolholder 12.

Then, the assembling of the tool-toolholder unit 10 provides that the bush 18 is inserted in the through-hole from the part of the tool 14 so that the circular crown surface 65 of the bush 18 abuts against the circular crown surface 57 of the tool 14.

In this position, the cylindrical body 64 of the bush 18 is received in the first hole 36 of the toolholder 12 and in the first cylindrical hole 56 of the tool 14 while the head 66 of the bush 18 is received in the second irregular hole 58 of the tool 14.

In particular, considering the homologous irregular profiles of the second irregular hole 58 and the head 66 as well as the inclination of the surface 68 of the head 66, the insertion of the bush 18 in the hole is done according to a predetermined orientation of the bush 18 relative to the tool 14.

In fact, in order to insert the bush 18 in the hole, the two planar surface portions 70 and the two cylindrical surface portions 72 of the head 66 of the bush 18 are placed adjacent to the two planar surface portions 60 and the two cylindrical surface portions 62 of the second irregular hole 58, respectively; in this conformation, the bush 18 could be inserted in the hole only according two orientations and in addition, the bush 18 is prevented from rotating relative to the tool 14, and consequently relative to the toolholder 12.

However, one of said two possible orientations is the preferred and used one, that is the orientation in which the inclined surface 68 of the head 66 of the bush 18 follows the profile of the front surface of the tool 14, as represented in figure 13. The bush 18 inserted as described has the threaded blind hole 73 turned towards the second hole 38 and the third hole 40 obtained in the toolholder 12.

In the continuation of the assembly of the tool-toolholder unit 10, a washer 22 is received in the cylindrical body 74 of the screw 20 which in turn is inserted in the second hole 38 and third hole 40 and screwed into the threaded blind hole 73 of the bush 18 so that the circular crown surface 75 of the screw 20 forces the washer 22 to abut substantially against the circular crown surface 39 between the second hole 38 and the third hole 40 of the toolholder 12.

In this position, not only the bush 18 can not rotate but in addition, it can not goes out of the hole in which it is received. Consequently, also the tool 14 is not detachable from the toolholder 12.

Besides, the particular conformation of the coupling makes impossible the rotation of the tool 14 relative to the toolholder 12 not only through the abutting disposition of the third face 48 and the fourth face 50 of the tool 14 against the first face 28 and the second face 30 of the toolholder 12, respectively, but also in particular through the insertion of the pin 16 in the hole 54 obtained in the tool 14.

The joining of the tool 14 to the toolholder 12 is therefore simple and makes practical and fast the fixing and dismounting of the tool 14 on and from the toolholder 12: it is sufficient to unscrew the only screw 20 by acting on the shaped cavity 77 of the screw 20 with a suitable wrench or spanner and remove the bush 18. Then, it is necessary only to lift the tool 14 from the toolholder 12 in order to remove the pin 16 from the hole 54 of the tool.

At the same time, the fixing between tool and toolholder is stable and rigid since any rotation between the two elements is avoided by inserting the pin 16 in the hole 54 and by the inclination of the faces abutting against each other. This peculiarity makes possible to avoid to put the screw in the maximum tension, which involves an increase of the life of the components of the tool-toolholder unit according to the invention.

It is obvious that the washer 22 can be also unused so that the head 76 of the screw 20 abuts directly against the circular crown surface 39 between the second hole 38 and the third hole 40 of the toolholder 12. Alternatively, the washer 22 can be replaced with another equivalent element.

According to a variant of the invention, a toolholder comprises an element in relief protruding from the upper face like the pin 16 protruding from the second face 30 of the previously described toolholder 12. According to this variant, the relief element is made in an only body with the toolholder and can have different shapes according to the constructive and functional requirements; the cavity obtained in the tool to receive the element in relief has a shape homologous to the relief element .

According to another variant of the invention, unlike the through-hole 54 of the previously described tool 14, a tool can have a slot having a width equal to the width of the pin 16 or an analogous relief element placed above the toolholder but having a different length; in this case, the length M (indicated in figure 7) of the hole is different and greater than the width L (indicated in figure 7) of the hole.

In case said slot is a cavity open also towards the rear face of the tool, analogous to the fifth planar face 52 of the tool 14, the tool can be placed against the toolholder also with a horizontal movement and not only with a vertical movement as in the case of the toolholder 12 and tool 14 described previously.

In any case, a coupling of this kind between slot or cavity in the tool and relief element or pin in the toolholder prevents a relative rotation between tool and toolholder.

According to another variant of the invention, the pin or relief placed above the body of the toolholder can develop not only centrally but also laterally from the second planar face of the toolholder. In particular, according to another variant of the invention, said relief can develop according to a direction inclined with respect to the second planar face from which it protrudes.

Likewise, the hole or the corresponding cavity obtained in the tool will have an analogous shape and direction of development so as to be joined in a stable manner.

A further variant of the invention provides that the tool and the bush are carried out in an only body so as to carry out a tool comprising a cylindrical body with a threaded hole that is inserted in the through-hole of the toolholder. A tool according to this variant of the invention provides an upper cavity, analogous to the hole 54 of the tool 14 described previously, which cavity allows to receive a relief element above the toolholder (like the pin 16 described previously), and at the same time, the cavity allows the insertion of the cylinder in the through-hole in the toolholder.

A technician of the sector can provide further changes or variants which are to be considered as included in the scope of protection of the present invention. The shape of the toolholder can vary with respect to the embodiment of the invention as described previously: for instance, the side faces may be non-parallel to each other while the profile may be different from an irregular quadrilateral. Besides, the first planar face and the second planar face of the toolholder may have an inclination different from an inclination of 95 degrees, as described previously; likewise, the same inclination is between the third face and the fourth face of the tool.

In addition, it is obvious that the relief element may be located in the tool instead of the toolholder, and a cavity having a shape homologous to the relief element may be obtained in the toolholder instead of the tool, which still allows to avoid minimal movements of rotation between the tool and the toolholder around the axis of the fixing screw.