MACHINE, AND RELATIVE OPERATING METHOD, FOR CRUSHING RUBBLE AND SIMILAR

TECHNICAL FIELD

The present invention relates to a machine, and relative operating method, for crushing rubble and similar.

More specifically, the present invention relates to a rotary-mill crushing machine for crushing rubble, rock and quarry materials in general, construction demolition and roadwork waste, or metal industrial waste such as scrap or similar.

BACKGROUND ART As is known, rotary-mill crushing machines comprise a casing or outer machine body; and a jagged-edged rotary mill mounted to rotate inside a crushing compartment or chamber formed inside the machine body. The top part of the crushing chamber communicates with the outside by a chute along which the work material is fed to the rotary mill; and the bottom part of the crushing chamber communicates with the outside via a hopper through which the crushed material drops by gravity from the chamber.

Rotary-mill crushing machines also comprise one or two baffles housed inside the crushing chamber, just above the rotary mill, to direct onto the rotary mill both the work material from the top feed chute, and the crushed material hurled in all directions by rotation of the mill. The baffles are positioned inside the crushing chamber so that their bottom lateral edges define, with the peripheral surface of the rotary mill, a gap or constriction, the width of which determines the maximum size of the crushed material from the crushing chamber.

To regulate the size of the crushed material from the crushing chamber, each baffle of the machine is normally hinged to and projects from the walls of the casing to oscillate freely about a horizontal supporting shaft parallel to the mill rotation axis, and is maintained in a tilted position inside the crushing chamber by casing connecting members designed to gradually adjust the tilt angle of the baffle with respect to the vertical and, hence, the width of the gap between the bottom lateral edge of the baffle and the peripheral surface of the rotary mill.

In addition, the casing connecting members are also designed to damp and absorb mechanical stress produced both by normal crushing of the rubble and by any large non-compressible bodies entering the crushing chamber.

In Patent Application WO2005/094998, this dual function is performed by a double-acting hydraulic cylinder, the outer tubular body of which is hinged to

the machine casing, the end of the movable rod of which is hinged to the back of the baffle, and which has a main piston and a floating auxiliary piston inside which divide the longitudinal cavity of the outer tubular body into three complementary variable-volume chambers. The main piston is fixed rigidly to the movable rod of the cylinder, and the auxiliary piston is fitted in axially sliding manner to an intermediate portion of the rod.

Though enabling fast tilt adjustment of the baffles without dismantling any major parts of the machine, in rotary-mill crushing machines of the type described in Patent Application WO2005/094998, the operator is still required to physically enter the crushing chamber to manually measure the distance between the bottom lateral edge of the baffle and the peripheral surface of the rotary mill, with all the drawbacks this entails. DISCLOSURE OF INVENTION

It is an object of the present invention to provide a rotary-mill crushing machine designed to eliminate the aforementioned drawbacks .

According to the present invention, there ■ is provided a machine for crushing rubble and similar, as claimed in Claim 1 and preferably, though not necessarily, in any one of the dependent Claims. According to the present invention, there is also provided a method of operating a machine for crushing rubble and similar, as claimed in Claim 10. BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a schematic section, with parts removed for clarity, of a machine for crushing rubble and similar, in accordance with the teachings of the present invention;

Figure 2 shows a section, with parts removed for clarity, of a component part of the Figure 1 machine. BEST MODE FOR CARRYING OUT THE INVENTION

Number 1 in Figure 1 indicates as a whole a rotary- mill crushing machine, which is particularly advantageous for crushing rubble, rock and quarry materials in general, construction demolition and roadwork waste, and metal industrial waste such as scrap or similar.

Crushing machine 1 substantially comprises a casing or outer machine body 2, in which an appropriately shaped crushing compartment or chamber 3 is formed; a jagged- edged rotary mill 4 mounted inside crushing chamber 3 to rotate axially about a preferably, though not necessarily, horizontal longitudinal axis A; and a drive unit (not shown) connected mechanically to rotary mill 4 to rotate it at a preferably, though not necessarily, constant speed about longitudinal axis A. The top part of crushing chamber 3 communicates directly with the outside via a work material inlet 5 formed in the top of casing or outer machine body 2; and the bottom part of crushing chamber 3 communicates

directly with the outside via a crushed material outlet 6 formed in the bottom of casing or outer machine body 2. Rotary mill 4 is housed inside crushing chamber 3, between inlet 5 and outlet 6, and is designed, as it rotates about longitudinal axis A, to crush the material fed by gravity into crushing chamber 3 through inlet 5.

In the example shown, casing or outer machine body 2 comprises, at inlet 5, a chute 7 by which the work material is fed to rotary mill 4 along a trajectory sloping at a predetermined angle with respect to the vertical; and the bottom of casing or outer machine body 2, where outlet 6 is located, is designed for connection to a known hopper (not shown) through which the crushed material drops by gravity from crushing chamber 3. With reference to Figure 1, crushing machine 1 also comprises at least one baffle 8 housed inside crushing chamber 3, just above rotary mill 4, and designed to direct onto the peripheral surface of the rotary mill 4 underneath both the incoming work material from chute 7, and the crushed material hurled in all directions by rotation of rotary mill 4.

More specifically, baffle 8 is housed inside crushing chamber 3 in a tilted position with respect to the vertical, so that the bottom lateral edge 8a of baffle 8 defines, with the peripheral surface of rotary mill 4, a gap or constriction, the width h of which determines the maximum size of the crushed material from crushing chamber 3.

More specifically, baffle 8 is suspended, or rather hinged to and projects, from the walls of outer casing 2 to oscillate freely, inside crushing chamber 3, about a rotation axis B parallel to longitudinal axis A of rotary mill 4, and is maintained in a predetermined tilted position by casing connecting members 9, which extend from outer casing 2 to the body of baffle 8, and provide for adjusting the tilt angle β of the baffle with respect to the vertical as required, and so adjusting as required the minimum distance between the bottom lateral edge 8a of baffle 8 and the peripheral surface of rotary mill 4, i.e. width h of said gap or constriction.

With reference to Figure 1, in the example shown, crushing machine 1 comprises two baffles 8. The first baffle 8 is housed inside crushing chamber 3, just above rotary mill 4 and directly facing chute 7; and the second baffle 8 is housed inside crushing chamber 3, behind first baffle 8, in the space between rotary mill 4 and the lateral wall of outer casing 2, and lower down so as to be aligned with the gap or constriction defined by bottom lateral edge 8a of first baffle 8 and the peripheral surface of rotary mill 4.

In addition, in the example shown, each of the two baffles 8 comprises a flat, substantially C- or L-shaped front plate 10 extending parallel to longitudinal axis A of rotary mill 4, with its concavity facing rotary mill 4; and a rear supporting frame 11 fitted on top with a supporting pin 12, which extends coaxially with rotation

axis B, and the two axial ends of which are inserted to rotate freely inside the lateral walls of outer casing 2.

With reference to Figures 1 and 2, each of casing connecting members 9 comprises at least one floating- piston hydraulic cylinder 13 interposed between the machine outer casing 2 and rear supporting frame 11 of baffle 8.

More specifically, each casing connecting member 9 may comprise one or moire parallel, side by side floating- piston hydraulic cylinders 13, each interposed between the machine outer casing 2 and rear supporting frame 11 of baffle 8.

Each hydraulic cylinder 13 extends coaxially with a longitudinal axis C lying preferably, though not necessarily, in a plane perpendicular to axes A and B, and substantially comprises a cylindrical tubular outer body 14 coaxial with longitudinal axis C; and a movable rod 15 coaxial with longitudinal axis C and at least partly inserted telescopically and in axially sliding manner inside cylindrical tubular body 14.

Cylindrical tubular body 14 is hinged to the machine outer casing 2 to oscillate freely about a rotation axis D perpendicular to longitudinal axis C of the cylinder and at the same time parallel to rotation axis B of baffle 8; and the free end of movable rod 15 is hinged to rear supporting frame 11 of baffle 8 to oscillate freely about a rotation axis E parallel to rotation axis D.

In addition, hydraulic cylinder 13 also comprises a

main piston 16 and a floating auxiliary piston 17, both mounted, to slide axially inside the constant-section longitudinal cavity 14a of cylindrical tubular body 14. Main piston 16 is fixed rigidly to the end of movable rod 15 inside cylindrical tubular body 14, and auxiliary piston 17 is fitted in axially sliding manner to an intermediate portion of movable rod 15.

With reference to Figure 2, main piston 16 and auxiliary piston 17 are both sized and designed to slide in fluidtight manner, parallel to longitudinal axis C, inside longitudinal cavity 14a of cylindrical tubular body 14, and to divide longitudinal cavity 14a into three complementary variable-volume chambers 18a, 18b, 18c aligned along longitudinal axis C of the cylinder. In the example shown, variable-volume chamber 18a is bounded laterally by main piston 16 and a first end wall of longitudinal cavity 14a; variable-volume chamber 18b is bounded laterally by auxiliary piston 17 and a second end wall of longitudinal cavity 14a; and variable-volume chamber 18c is bounded laterally by main piston 16 and auxiliary piston 17.

The two variable-volume chambers 18a, 18b at the two ends of longitudinal cavity 14a - hereinafter also referred to as lateral chambers - are filled with pressurized oil; and variable-volume chamber 18c hereinafter also referred to as the central chamber - communicates directly with a pressurized-gas or -fluid source along a connecting conduit 19 formed, in the

example shown, inside movable rod 15. The volume of variable-volume chamber 18c therefore depends on the total volume of variable-volume chambers 18a and 18b.

In this connection, cylindrical tubular body 14 has two pressurized-oil inlets 13a, 13b, by which to feed or withdraw pressurized oil to or from the two variable- volume chambers 18a, 18b at the two ends of longitudinal cavity 14a; and the pressurized-gas or -fluid source may advantageously be defined by the external environment. Alternatively, the pressurized-gas or -fluid source may obviously also be defined by a branch of the hydraulic circuit of the machine.

More specifically, with reference to Figure 2, when movable rod 15 withdraws inside cylindrical tubular body 14, the volume of variable-volume chamber 18a is reduced, and the total volume of variable-volume chambers 18b and 18c is increased.

With reference to Figure 2, in the example shown, cylindrical tubular body 14 substantially comprises a cylindrical tubular sleeve 20, of appropriate length, extending coaxially with longitudinal axis C; and an endpiece 21 and a cap 22 closing the two ends of the sleeve. Cap 22 has a central through hole sized so that movable rod 15 slides through it with no pressurized-oil leakage.

Variable-volume chamber 18a is therefore bounded laterally by the body of main piston 16 and by endpiece 21; and variable-volume chamber 18b is bounded laterally

by the body of auxiliary piston 17 and by cap 22.

In the example shown, movable rod 15 is defined by a cylindrical bar 23 of appropriate length, and by a fork 24 fixed rigidly to the end of the bar outside cylindrical tubular body 14. Fork 24 is hinged to rear supporting frame 11 of baffle 8 by a known cylindrical pin coaxial with axis E.

With reference to Figure 2, in addition to the above, connection members 9 also comprise, for each hydraulic cylinder 13, a relief valve 25 and a pressurized-oil storage tank 26, both fitted to hydraulic cylinder 13 in direct communication with variable-volume chamber 18a of cylindrical tubular body 14.

Relief valve 25 selectively allows pressurized-oil outflow from variable-volume chamber 18a, when the oil pressure inside the same chamber exceeds a predetermined first threshold value, and is preferably, though not necessarily, defined by an electronically controlled proportional maximum-pressure valve; and storage tank 26 stores a variable amount of pressurized oil from variable-volume chamber 18a, when the oil pressure in the same chamber exceeds a predetermined second threshold value lower than the first threshold value of relief valve 25. Finally, casing connecting members 9 comprise, for each hydraulic cylinder 13, a position sensor 27 fitted to hydraulic cylinder 13 to supply an electric signal indicating the instantaneous position of movable rod 15

with respect to cylindrical tubular body 14, or, more specifically, an electric signal indicating the instantaneous length of the portion of movable rod 15 projecting outside cylindrical tubular body 14. In the example shown, relief valve 25, storage tank 26, and position sensor 27 are all fixed to endpiece 21 of cylindrical tubular body 14.

More specifically, with reference to Figure 2, storage tank 26 is defined by a conventional pack-type pressurized-oil accumulator 26 substantially comprising an airtight cylindrical container 28, which is fixed to and projects from endpiece 21 of cylindrical tubular body 14, and has an elastically deformable partition membrane 29 inside which divides the inner cavity into two complementary variable-volume chambers. The first chamber communicates directly with variable-volume chamber 18a of cylindrical tubular body 14 and stores pressurized oil; and the second chamber is isolated from the outside, and contains gas at a predetermined adjustable reference pressure corresponding to said second threshold value governing intervention of storage tank 26.

In the example shown, position sensor 27 is defined by a conventional magnetostrictive position transducer 27, which determines the real-time distance, parallel to longitudinal axis C of the cylinder, between movable rod 15 and endpiece 21 defining the end of longitudinal cavity 14a of cylindrical tubular body 14.

Position transducer 27 comprises a reference rod 30, which extends inside longitudinal cavity 14a of cylindrical tubular body 14, coaxially with longitudinal axis C and from endpiece 21 of cylindrical tubular body 14, and telescopically engages a longitudinal hole 30a formed in cylindrical bar 23 of movable rod 15; a magnetic cursor 31 fitted in axially sliding manner to reference rod 30 and rigidly to cylindrical bar 23 of movable rod 15; and an electronic central control unit 32, which supplies the machine control unit (not shown) in known manner with an electric signal depending on the position of magnetic cursor 31 along reference rod 30.

With reference to Figure 2, casing connecting members 9 also comprise two on-off valves 33, 34, each for regulating pressurized-oil flow to and from a respective variable-volume chamber 18a, 18b of cylindrical tubular body 14 through the corresponding pressurized-oil inlet 13a, 13b.

Operation of crushing machine 1 as a whole will be clear from the foregoing description with no further explanation required.

Operation of casing connecting members 9, on the other hand, will be described with reference to tilt adjustment of one baffle 8 only, and starting from a parking configuration, in which baffle 8 is at the maximum distance from rotary mill 4, and movable rod 15 of hydraulic cylinder 13 is fully withdrawn inside cylindrical tubular body 14, with auxiliary piston 17

resting against main piston 16. In this configuration, the respective volumes of variable-volume chambers 18a and 18c are minimum, and the volume of variable-volume chamber 18b is maximum. In actual use, the operator sets, on the machine control unit (not shown) , the desired size of the crushed material from crushing chamber 3, which corresponds to a given width h of the gap or constriction defined by the bottom lateral edge 8a of baffle 8 and the peripheral surface of rotary mill 4; and the machine control unit controls connecting members 9 of baffle 8 to position the bottom lateral edge 8a of baffle 8 at the desired distance h from the peripheral surface of rotary mill 4.

More specifically, the machine control unit opens on-off valves 33 and 34, and the machine hydraulic circuit feeds pressurized oil through inlet 13a into variable-volume chamber 18a to push movable rod 15 of hydraulic cylinder 13 slowly out of cylindrical tubular body 14. The pressurized oil fed into variable-volume chamber 18a increases the volume of such chamber and accordingly reduces the volume of variable-volume chamber 18b, from which pressurized oil is drained through inlet 13b and, obviously, fed back to the machine hydraulic circuit . The machine control unit keeps on-off valves 33 and 34 open to continue extending movable rod 15 and so rotate baffle 8 gradually about rotation axis B until flat front plate 10 comes to rest on the peripheral

surface of rotary mill 4, and the machine control unit zeroes the value of width h of the gap or constriction defined by the bottom lateral edge 8a of baffle 8 and the peripheral surface of rotary mill 4. In connection with the above, it should be pointed out that, when extending movable rod 15, auxiliary piston 17 remains resting against main piston 16, and the minimum volume of variable-volume chamber 18c remains unchanged. Once flat front plate 10 of baffle 8 is positioned resting on the peripheral surface of rotary mill 4, the machine control unit immediately closes on-off valves 33, 34 to cut off pressurized-oil flow to variable-volume chamber 18a, and acquires from position sensor 27 - or, rather, from electronic central control unit 32 - the value of the distance between movable rod 15 and endpiece 21 defining the end of longitudinal cavity 14a.

In other words, by means of position sensor 27, the machine control unit is able to determine the stop position value of movable rod 15 with respect to cylindrical tubular body 14; which position is then used as a reference to position baffle 8.

Once the reference parameters of movable rod 15 in the stop position are acquired, the machine control unit opens on-off valves 33 and 34 again, and the machine hydraulic circuit feeds pressurized oil through inlet 13b into variable-volume chamber 18b to ease movable rod 15 of hydraulic cylinder 13 back into cylindrical tubular

body 14. The pressurized oil fed into variable-volume chamber 18b increases the volume of such chamber and accordingly reduces the volume of variable-volume chamber 18a, from which pressurized oil is drained through inlet 13a.

When easing the movable rod back inside cylindrical tubular body 14, the axial thrust of the oil flow into variable-volume chamber 18b is obviously exerted entirely on auxiliary piston 17, which therefore remains resting against main piston 16, so the minimum volume of variable-volume chamber 18c remains unchanged.

Controlling the instantaneous position of movable rod 15 with respect to cylindrical tubular body 14 by means of the signals from position sensor 27, the machine control unit keeps on-off valves 33 and 34 open to continue easing movable rod 15 back inside cylindrical tubular body 14 until the axial travel of movable rod 15 with respect to the stop position equals a predetermined value, which is a function of the desired value of width h of the gap defined by bottom lateral edge 8a of baffle 8 and the peripheral surface of rotary mill 4.

The value of width h of the gap between bottom lateral edge 8a of baffle 8 and the peripheral surface of rotary mill 4 varies, in fact, as a function of the axial travel of movable rod 15 with respect to the established stop position. Consequently, given the stop position of movable rod 15 and the mathematical relationship between gap width h and the variation in the position of movable

rod 15 with respect to cylindrical tubular body 14, the machine control unit is able to control hydraulic cylinder 13 to position movable rod 15 so that the bottom lateral edge 8a of baffle 8 is the desired distance h from the peripheral surface of rotary mill 4.

With reference to Figure 2, once movable rod 15 is in the desired position inside cylindrical tubular body 14, thus setting baffle 8 to the desired work position (i.e. with bottom lateral edge 8a of baffle 8 the desired distance h from the peripheral surface of rotary mill 4), the machine control unit closes on-off valves 33 and 34 to prevent any further pressurized-oil flow to or from variable-volume chambers 18a and 18b.

Variable-volume chambers 18a, 18b of cylindrical tubular body 14 both being filled completely with pressurized oil, i.e. non-compressible fluid, closing on- off valves 33 and 34 locks baffle 8 in the desired work position, and crushing machine 1 in the work configuration, i.e. ready to crush the material fed into crushing chamber 3.

In addition, closing on-off valve 34 prevents any further axial travel of auxiliary piston 17 along movable rod 15 of hydraulic cylinder 13.

When the machine is running normally, and a large non-compressible body jams inside the gap between baffle 8 and rotary mill 4, movable rod 15 is subjected to severe axial thrust, which causes it to withdraw inside cylindrical tubular body 14, thus pushing main piston 16

towards endpiece 21. But since variable-volume chamber 18a is filled completely with non-compressible fluid, the axial thrust transmitted by movable rod 15 to main piston 16 produces a rapid increase in oil pressure inside variable-volume chamber 18a.

When the oil pressure inside variable-volume chamber

18a exceeds the gas pressure inside storage tank 26, i.e. the second predetermined threshold value, partition membrane 29 in storage tank 26 deforms to allow pressurized-oil to flow from variable-volume chamber 18a into the tank. The outflow of pressurized-oil from variable-volume chamber 18a, in turn, permits a rapid reduction of the total volume of such chamber, thus resulting in axial displacement of main piston 16 and withdrawal of movable rod 15.

In the event partial withdrawal of movable rod 15 inside cylindrical tubular body 14 is followed by a sharp fall in oil pressure inside variable-volume chamber 18a - indicating sufficient lift of baffle 8 to allow the non- compressible body to pass between baffle 8 and rotary mill 4 - the gas inside storage tank 26 forces pressurized oil back into variable-volume chamber 18a, which increases in volume to move main piston 16 back into position resting against auxiliary piston 17, and so restore baffle 8 to its original work position.

Conversely, a persistent increase in oil pressure inside variable-volume chamber 18a, despite partial withdrawal of movable rod 15 - indicating insufficient

lift of baffle -8 to allow the non-compressible body to pass between baffle 8 and rotary mill 4 - activates relief valve 25 which, when the first threshold value is exceeded, allows controlled outflow from variable-volume chamber 18a of enough pressurized oil to withdraw movable rod 15 sufficiently to let the non-compressible body through .

In this case, the machine control unit resets baffle 8 to its original work position by temporarily opening on-off valve 33 to feed further pressurized oil into variable-volume chamber 18a and so move main piston 16 back into position resting against auxiliary piston 17.

In connection with the above, it should be pointed out that, as main piston 16 moves axially inside cylindrical tubular body 14 to absorb the mechanical stress caused by a non-compressible body in the gap between baffle 8 and rotary mill 4, auxiliary piston 17 remains always stationary inside cylindrical tubular body 14 to maintain the original work position reference of baffle 8.

Being permanently isolated from the machine hydraulic circuit and filled completely with non- compressible fluid, variable-volume chamber 18b, in fact, is prevented from effecting any change in volume, and so transforms auxiliary piston 17 into an adjustable stop for main piston 16. Any variation in the volume of variable-volume chamber 18a, in fact, is compensated by a corresponding variation in the volume of variable-volume

chamber 18c which, communicating directly with the outside or with the pressurized-fluid source by means of connecting conduit 19, can effect a rapid change of its total volume with no restriction whatsoever. The advantages of crushing machine 1 as described and illustrated herein are obvious. By means of hydraulic cylinders 13 with position sensors 27, crushing machine 1 provides for fully automatically orienting baffles 8 inside crushing chamber 3, and positioning the bottom lateral edge 8a of each baffle 8 at the correct distance from peripheral surface of rotary mill 4.

Moreover, crushing machine 1 also provides for fully automatically compensating wear of flat front plates 10 of baffles 8 caused by continual impact of the work material, thus ensuring correct sizing at all times of the crushed material from crushing chamber 3.

Clearly, changes may be made to crushing machine 1 as described and illustrated herein without, however, departing from the scope of the present invention. For example, position sensor 27 may be designed to supply a first electric signal indicating the instantaneous position of movable rod 15 with respect to cylindrical tubular body 14, and a second electric signal indicating the instantaneous position of auxiliary piston 17 inside longitudinal cavity 14a of cylindrical tubular body 14.

In which case, position sensor 27 may comprise a two-channel magnetostrictive position transducer 27 for

determining both the real-time distance between movable rod 15 and endpiece 21 defining the end of longitudinal cavity 14a of cylindrical tubular body 14, and the realtime distance between auxiliary piston 17 and endpiece 21, both distances obviously being measured parallel to longitudinal axis C of the cylinder.

In which case, in addition to magnetic cursor 31, position transducer 27 also comprises a second magnetic cursor 31' fitted in axially sliding manner to cylindrical bar 23 of movable rod 15 and rigidly to the body of auxiliary piston 17; and electronic central control unit 32 of position transducer 27 supplies the machine control unit (not shown) with a first electric signal as a function of the position of magnetic cursor 31 along reference rod 30, and a second electric signal as a function of the position of magnetic cursor 31' along reference rod 30.