EP2528688B1

EP2528688B1 - Preliminary crushing device and related method

Info

Publication number: EP2528688B1
Application number: EP11711628.5A
Authority: EP
Inventors: Claudio Colombo
Original assignee: Colombo Giovanni Srl
Current assignee: Colombo Giovanni Srl
Priority date: 2010-01-29
Filing date: 2011-01-28
Publication date: 2015-03-11
Anticipated expiration: 2031-01-28
Also published as: ES2541002T3; ITUD20100016A1; IT1398438B1; WO2011092588A1; PL2528688T3; EP2528688A1

Description

FIELD OF THE INVENTION

The present invention concerns a preliminary crushing device and relative method which can be used in a garbage disposal plant for crushing, advantageously but not exclusively, scrap such as vehicles, trailers, collected material, domestic appliances or other.
In particular the present invention is used to carry out a preliminary crushing treatment on scrap, also in a packed form, before this is sent on to subsequent working, for example to be broken up in a hammer mill, and subsequent separation of the iron, plastic, glass or other materials.
EP-B-0.958.059 discloses the features of the preamble of the main claims.

BACKGROUND OF THE INVENTION

Shredding mills are known for shredding and fragmenting scrap, used in plants for the disposal of garbage.
Known shredding mills comprise a shredding chamber having a shredding unit consisting, for example, of a plurality of shredding hammers.
The shredding chamber is disposed downstream of a preliminary crushing device, provided with a sloping slide to convey the scrap to be shredded and at least two crushing rollers, disposed transversely to the slide and each provided with several toothed profiles able to determine a compression, rending and crushing action of the incoming garbage. In this way the scrap is reduced in size so as to be able to be put in the shredding chamber. Moreover, in the case of the treatment of disused vehicles and/or domestic appliances, their preliminary crushing allows to prevent dangerous explosions and fires inside the shredding chamber, due to the presence of fuels and combustible liquids in the tanks or in gas and/or LPG cylinders.
The crushing rollers are suitable to cooperate both reciprocally, due to the effect of the joint rotation of the corresponding toothed profiles, and also with the conveyor slide to carry out the preliminary crushing action. The crushing rollers rotate, in opposite directions of rotation, at different rotation speeds, based on a predetermined reduction ratio, regulated by a reduction mechanism connected to them.
In particular, a first of the rollers, or low-speed roller, is disposed above and rotates at a predetermined rotation speed, while a second of said rollers, or high-speed roller, is disposed below and rotates at a greater speed than the first roller, according to said reduction ratio. The difference in speed and counter-rotation of the rollers allows the toothed profiles of the first roller to draw the scrap into the space between the rollers so that the toothed profiles of the second roller, which rotates at a greater speed, exerts a stretching and rending action.
With this treatment the density and the size of the scrap is reduced promoting the subsequent shredding by means of hammer rollers in the shredding chamber.
The preliminary crushing device is also provided with an oscillating portion or wall, disposed in proximity to the crushing rollers, which is mobile, for example, alternatively between at least a first inactive position in which it is disposed aligned with the slide in order to allow the scrap to advance, and at least a second position in which it is made to rotate around one of its lower ends, so as to move one of its upper portions toward the crushing rollers. The oscillating wall also has a plurality of hooked portions made on the surface facing toward the crushing rollers. The hooked portions are disposed both in the space of the oscillating portion comprised between the two rollers, and also in correspondence to the toothed profile of the upper roller. The hooked portions are directed so as to allow the sliding of the scrap downward, but they prevent it from rising rear up in order to determine the rending thereof.
Therefore, if there is an overload or a blockage of the crushing rollers, for example due to the presence of hard scrap, the rotation of both rollers is inverted and the oscillating wall is moved alternately between its first and its second position for a predetermined interval of time. In this way, the scrap possibly trapped between the rollers is made to move rear by means of the toothed profiles and, because of the inversion of the rotation of the rollers, the scrap is made to rise along the oscillating wall. This allows to exert, by means of the hooked portions of the oscillating wall, an additional rending action on the scrap which caused the blocking or overloading.
At the end of this predetermined interval of time, the normal direction of rotation of the crushing rollers is restored in order to feed the scrap toward the shredding chamber. The oscillating plane is also positioned stably in its inactive position. All this allows to treat the specific portion of the scrap which has caused the block or overload in a different condition, for example rent differently, and therefore to treat it with the rollers and convey it to the shredding chamber.
One disadvantage of known preliminary crushing devices is that it is not possible to crush in an efficient manner all the material and scrap introduced. Indeed it is becoming more and more frequent to carry out a densification of the scrap in a packed condition, so as to limit the costs of transport from the collecting points to the disposal and treatment plants. In these cases it is not always possible to achieve an efficient attachment and drawing action, especially when the size of the packs of scrap introduced is greater than the distance between the toothed profile of the first roller and the surface of the oscillating wall.
This substantially determines a condition of "floating" of the packs of scrap in proximity to the rollers and the need for a manual intervention by an operator in order to facilitate attachment. This in turn causes a reduction in the production capacity of the plant and, therefore, an increase in management costs, and a great danger for the safety of the operator who often intervenes manually to remove the blockage.
A further disadvantage is that it is not possible to continuously feed the preliminary crushing devices and therefore the crushing chamber below, given that, as well as possible interference with packs of scrap in the floating condition, the possible attachment of further scrap by the low-speed roller subtracts part of the mechanical torque actually used for the fragmentation action.
One purpose of the present invention is to achieve a preliminary crushing device for a garbage disposal plant which allows a preliminary crushing of scrap in whatever form it comes in, both loose or packed.
A further purpose of the present invention is to achieve a preliminary crushing device for scrap which allows an increase in productivity of the disposal plant associated to it and a reduction in energy consumption during its functioning.
A further purpose of the present invention is to perfect a preliminary crushing method for scrap which allows to treat scrap in whatever forms it comes in and to increase crushing productivity.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.
In accordance with the above purposes, a preliminary crushing device according to the present invention can be used in a garbage disposal plant for crushing, advantageously but not exclusively, scrap such as disused cars, collected materials, domestic appliances or others, whether in the form of loose material or in packs of scrap.
The preliminary crushing device comprises means to convey the scrap and crushing means, disposed at a predetermined operating distance from the conveying means.
The conveying means comprise an introduction portion such as an inclined plane or slide, and a pressure element, disposed after the introduction portion, provided with hook elements able not to interfere with the feed of the scrap towards the crushing means.
The pressure element is selectively mobile between at least a first position, or inactive position, in which it is disposed substantially aligned with the introduction portion, so as to define a single advance profile of the scrap, and a second position in which protrudes forward with respect to the introduction portion so as to bring the hook portions closer to the crushing means.
In this second position, assumed in the case of overloading at the same time as the inverse rotation of the crushing rollers, the pressure element also impedes the advance of other scrap possibly fed into the introduction portion, cooperating with the crushing means in order to determine the movement of part of the scrap not completely crushed toward the first portion and its rending by means of the hook elements.
In this way it is possible to manage possible blockages or overload conditions of the crushing means, allowing to carry out further working by temporarily inverting the direction of feed of the scrap, at the same time carrying out a rending of the scrap which has caused the blockage or overload condition.
According to one feature of the present invention, the pressure element has at least a third position in which it is disposed with at least its upper end in a recessed manner, that is, retracted backward, with respect to the introduction portion or slide so as to determine a step with respect to the lower end of the introduction portion and to increase, at least temporarily, the operating distance between the crushing means and the conveying means.
Thanks to this retracted position of the pressure element, and the step toward the inside of the plane of feed which forms with respect to the lower end of the slide, a pack of scrap which, because of its size, might be "floating" on the upper roller without continuing its descent, is inclined with respect to its position of feed, enabling it to be gripped by the teeth of the low-speed roller and therefore allowing the pack to advance toward the crushing zone.
In this way, simply by modifying the relative position of the conveying means with respect to the crushing means, for example depending on the size of the scrap introduced, it is always possible to get a grip on the scrap, and therefore to crush it efficiently. This is also possible in the case where the scrap is introduced in a pack, in which the step which forms between the introduction portion and the pressure element allows to increase the inclination of the scrap in pack form in correspondence to the crushing means, facilitating the grip and reducing the probability of the "floating" condition as in the state of the art.
Therefore the movement of the pressure element in more than two different positions, of which at least one position retracted with respect to the feed slide, allows to achieve different working cycles, for example, automatic or partially automatic, depending on the specific type of scrap introduced, either loose or in packs. In this way it is possible to manage different feed conditions, reducing the probability of unwanted "floating" conditions of scrap in packed form and efficiently managing possible blockages or overload conditions.
According to a variant of the present invention, the crushing means comprise at least two counter-rotating rollers, that is, an upper crushing roller or low-speed roller and a lower roller or high-speed roller, both provided with toothed profiles suitable to cooperate with each other in order to crush the scrap.
The two crushing rollers are able to counter-rotate alternately at different speeds between a first direction of rotation in order to feed and crush the scrap between the rollers, and a counter-direction of rotation, based on the position of the pressure element, in order to determine the return of part of the scrap not crushed or partially crushed toward the introduction portion and its rending by means of the first roller and the hook elements.
According to a further variant of the present invention, the crushing rollers are driven in an independent manner with respect to each other by means of associated motor means.
According to a further variant of the present invention, the crushing rollers are able to rotate according to a predetermined speed ratio.
In this way, each crushing roller is able to use its own independent fragmentation torque in every operating condition, even in an overloaded condition. That in turn allows to feed the scrap substantially continuously into the preliminary crushing device, preventing, when the scrap is gripped by the first roller, part of the crushing torque from being detracted from the second of the two rollers, as happens in the state of the art.
According to a further variant of the present invention, the hook elements are disposed parallel to the toothed profiles in the direction of feed in a substantially intermediate position between one profile and the other.
In this way, especially in the case where the device is fed with scrap in packed form, it is possible to obtain a more efficient grip of the scrap both in its normal feed step and also when it rises in order to overcome the blockages or overload conditions of the crushing rollers.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

fig. 1 is a three-dimensional view of a preliminary crushing device according to the present invention;
fig. 2 is a partially sectioned three-dimensional view of the device in fig.1;
fig. 3 is a lateral view of fig. 2;
fig. 4 is a schematic lateral view of the device in fig. 1 in a first operating configuration;
fig. 5 is a schematic lateral view of the device in fig. 1 in a second operating configuration;
fig. 6 is a schematic lateral view of the device in fig. 1 in a third operating configuration;
fig. 7 is a schematic lateral view of the device in fig. 1 in a fourth operating configuration.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify common elements in the drawings that are substantially identical. It is understood that elements and characteristics of one form of embodiment can conveniently be incorporated into other forms of embodiment without further clarifications.

DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF EMBODIMENT

With reference to the attached drawings a preliminary crushing device 10 according to the present invention comprises a box-like body 20, provided with a conveying region 22 in which there is an introduction slide 27 and a compression wall 30. The device 10 also comprises a crushing unit 50, having an upper crushing roller 52 and a lower crushing roller 54, in turn provided with toothed crowns 58 for crushing.
The box-like body 20 is provided with a rear wall 25 and two opposite lateral walls 26 able to act, together with a lid 21 opposite the rear wall 25 (shown in semi-transparency in fig. 1) as containing elements for the crushing unit 50 and for the scrap 13 introduced into the device 10, either loose or in packed form. Crushing rollers 52, 54 are also mounted on the lateral walls 26, as will be explained hereafter.
In particular the box-like body 20 comprises an introduction aperture 23 of the conveying region 22, disposed above the box-like body 20, and a discharge exit 24 for the outlet of the scrap crushed by the crushing unit 50.
The introduction aperture 23 is advantageously disposed downstream of a scrap feed device of the known type, not shown, such as a conveyor belt or movement member.
The discharge exit 24 is, on the other hand, associated to a corresponding introduction entrance of a scrap treatment device, in turn disposed downstream of the device 10, such as a shredding chamber with hammers of the known type, not shown in the attached drawings.
The rear wall 25 defines in its portion facing toward the inside of the box-like structure 20 the introduction slide 27, having a predetermined inclination such as to allow the scrap fed into the introduction aperture 23 to slide due to gravity toward the crushing unit 50.
The compression wall 30 is disposed inside the box-like structure 20 and is disposed consecutive to the slide 27, substantially according to the same inclination. The movement wall 30 is selectively movable between different operating positions, in at least one of which it is disposed so as to define a single profile with the slide 27 for the feed of the scrap toward the rollers 52, 54.
In particular, the compression wall 30 is pivoted in correspondence to a lower end to a rotation pin 32 attached to the lateral walls 26 of the box-like body 20 so as to allow the selective movement thereof between said operating positions, as will be described hereafter. The wall 30 is also connected in correspondence to one of its upper ends to one or more linear actuators 34, for example a movement piston, disposed in the lower portion of the box-like body 20 and suitable to move the walls 30 between said different operating positions.
The wall 30 is also provided with a plurality of hook-type protuberances 40 made on its upper surface and disposed substantially parallel to the normal direction of feed of the scrap, indicated with the arrow "A". The protuberances 40 are also disposed so as not to interfere mechanically with the sliding of the scrap toward the crushing unit 50, but to impede its ascent, causing it to rend, when the crushing rollers 52, 54 invert their direction of rotation and determine a temporary ascent of part of the scrap toward the slide 27 as will be described hereafter.
The hook-type protuberances are also distributed in a regular manner on the width of the wall 30, in a manner coordinated to the disposition of the toothed crowns 58 of the rollers 52, 54, so as to define adequate and efficient inclinations of the entering scrap with respect to the toothed crowns 58.
The wall 30 is mobile between at least four different operating conditions as shown in figs. 4 to 7. The wall 30 can be disposed in a first portion or inactive position (fig. 4) in which it is substantially aligned with the introduction slide in order to allow the scrap to advance toward the rollers 52, 54.
The wall 30 is movable, rotating around the pin 32 due to the drive of the actuator 34, into a second position (fig.5), or closed position in which it is inclined forward and disposed near to the rollers 52, 54 so as to render the operating distance between the rollers 52, 54 and the hook-type protuberances 40 smaller. In particular, in this second position the wall 30 impedes the advance toward the rollers 52, 54 of further scrap possibly introduced into the aperture 23, making it possible, by means of the hook-type protuberances 40, to rend part of the scrap which is made to rise when the rollers 52, 54 invert their direction of functioning.
This second position is assumed in the case of scrap which is particularly difficult to rend, so that in this condition the crushing rollers 52, 54 invert their rotation, the upper end of the wall blocks a further advance of other scrap from the slide 27, and the teeth of the crushing rollers 52, 54, in cooperation with the hooks 40 of the wall 30, carry out the rending operation on the scrap without the scrap falling toward the shredding chamber positioned downstream. Once the desired result is achieved, the wall 30 returns to the position aligned to the slide 27 in fig. 4 and the crushing rollers 52 and 54 return to their normal direction of rotation.
The wall 30 is also movable into a third position (fig. 6) in which it is at least partially disposed recessed with respect to the slide 27, so that its upper end, that is, the one nearest the slide 27, defines with the lower end of the slide 27 a step 28 of desired height in order to increase, at least temporarily, the operating distance of the wall 30 with respect to the rollers 52, 54.
The wall 30 is also movable into at least a fourth position, intermediate between the inactive position and the closed position in which the operating distance between the rollers 52, 54 and the hook-type protuberances 40 is greater than the corresponding operating distance achieved in the closed position.
The upper roller 52, or low-speed roller, and the lower roller 54 or high-speed roller, are disposed in a substantially transverse direction with respect to the direction of feed "A" and are mounted on the lateral walls 26 of the box-like body 20, at a predetermined reciprocal distance which guarantees an adequate crushing action of the scrap in the space defined between the rollers 52, 54 and so as to obtain the desired operating distances when the wall 30 is disposed in its different positions.
The rollers 52, 54 are suitable to cooperate reciprocally by means of the corresponding toothed crowns 58 so as to carry out the crushing of the scrap. The rollers 52, 54 are suitable to counter-rotate alternately, at different rotation speeds, in two different directions of rotation. In particular the rollers 52, 54 are suitable to rotate simultaneously in a first functioning condition in the directions indicated by the arrows "F1" and "F2" in order to carry out the crushing of the scrap introduced, and in a second functioning condition in the directions indicated by the arrows "F3" and "F4" in order to make the scrap disposed between the rollers 52, 54 rise and to rend it by means of the hook-type protuberances 40.
Advantageously the rollers 52, 54 are driven independently with respect to each other by means of corresponding hydraulic motors, not shown, and commanded in their turn by independent hydraulic pumps. In particular, the speed ratio between the two rollers 52, 54 must be more than at least 1:3. This defines an equal ratio between the power of the corresponding electric command motors of the hydraulic pumps and therefore, of the same ratio relating to the delivery rates of the hydraulic pumps.
Finally, the toothed crowns 58 provided with rending teeth 59, which exit from the rollers radially or according to another suitable inclination, are disposed in a regular manner along the development of the rollers 52, 54. In this case the toothed crowns 58 are substantially equidistant and reciprocally staggered between one roller and the other, so as to produce an efficient crushing action of the scrap gripped first by the lower roller 52 and subsequently rent by the action of both rollers 52, 54.
The preliminary crushing device as described so far functions as follows.
In normal operating conditions the compression wall 30 is positioned in the first or in the third position and the rollers 52, 54 rotate respectively according to directions indicated by the arrows F1 and F2 (figs. 3, 4 and 6) so as to allow the scrap to be crushed to be gripped by the first roller 52 and subsequently to be crushed: the scrap is rent due to the effect of the greater rotation speed of the lower roller 54 and is subsequently discharged in the direction indicated by the arrow "U". The positioning of the wall 30 in the first or the third position can be selectively modified depending on the size of the scrap introduced.
For example, in the case of crushing loose scrap, the wall 30 can stay positioned in its inactive position, allowing the scrap to slide toward the rollers 52, 54 and to be subsequently crushed.
In the case of crushing scrap in packed form, the pack of scrap 30 (fig. 6) can be bigger in size than the space between the teeth of the upper crushing roller 52 and the hooks 40 of the wall 30, so that it is not gripped and rent between these, but is kept in a so-called "floating" condition in which it does not continue its travel toward the lower crushing roller 54.
In this case, the wall 30 is positioned in the third position so that the upper end of the wall 30 defines said step 28 with the lower end of the slide 27, in order to allow a further inclination of the pack of scrap 30 with respect to the feed surface of the slide 27 and therefore allow the scrap to be subsequently gripped by the upper roller 52. Moreover, the disposition of the hook-type protuberances 40 on the wall 30 also allows to incline the packs of entering scrap transversely with respect to the direction of feed, thus promoting the crushing of the scrap.
As can easily be seen in fig. 6, the pack of scrap which, in a condition with the wall 30 aligned to the slide 27, would remain with its lower surface resting against the teeth of the crushing roller 52 without moving any further forward but "floating" on them, with the wall 30 retracted it inclines toward the inside of the slide 27, thus allowing the teeth of the crushing roller 52 to grip it and, in cooperation with the hooks 40, to determine the reduction in volume thereof and therefore its advance downstream.
In the case where there is an overload condition or blockage of the rollers 52, 54, the direction of rotation of the rollers 52, 54 is inverted according to the direction indicated by the arrows F3, F4 and the wall 30 is positioned in the second or fourth position. In this way, as the wall 30 protrudes with respect to the slide 27, the further introduction of scrap by the slide 27 is impeded and the inversion of the direction of rotation of the rollers determines the movement of that part of the scrap which has caused the condition of overload or blockage in the direction indicated by the arrow "R". In this condition the portion of scrap is moved by the upper roller 52 and further rent by means of the hook-type protrusions 40.
After a predetermined interval of time, the normal direction of rotation of the rollers 52, 54 is restored according to the directions F1, F2 and the wall is returned for example to the inactive position, allowing to efficiently crush the scrap thus further rent.
In the case in which the device is fed manually, for example controlled by an operator who decides the times the scrap will be introduced, it is advisable to provide signaling means, such as a luminous traffic light signaler with three colors - red, amber and green - suitable to supply indications on the actual functioning state of the device 10 so as to block the further introduction of scrap into the case of overload or blockage of the rollers 52, 54.
Moreover, the device 10 provides the presence of at least a pressure transducer, not shown, able to detect the working pressure of the hydraulic circuits which drive the corresponding motors, in order to detect possible blockage or overload conditions.
The device 10 can be made to function according to automatic or partially automatic work cycles on the basis, for example, of the type of scrap introduced, either loose scrap or in packed form.
In this case the device 10 comprises at least a control and supervision unit, not shown, such as one or more PLC units or other, able to supervise and control the operating parameters of the device, such as the pressures of the hydraulic circuits, the rotation speed of the rollers 52, 54. The device 10 also comprises a control panel provided with specific buttons and/or selectors which can be activated manually. For example, it is possible to provide at least an emergency button, a selector to select the specific program to be activated, a command lever to directly modify the positioning of the wall 30 between the second, the third and the fourth position, and a button to activate the simultaneous inversion of rotation of the rollers 52, 54.
Three possible automatic or semi-automatic examples are summarized hereafter.

Program for the preliminary crushing of scrap in packed form

The rollers 52, 54 rotate in the normal direction of rotation of fragmentation (F1, F2), the wall 30 is positioned in the third position, which is optimal for scrap in packed form, increasing the operating distance between the rollers 52, 54 and the wall 30.
If, for at least 15s consecutively, or other predetermined intervals of time, the pressure values detected by means of the relative transducers in the hydraulic circuits driving the rollers 52, 54 remain below a set minimum value, it is probable that there will be a situation of "floating" of the packs of scrap introduced. The wall 30 is then moved automatically between the third position and the second or fourth position (figs. 5 and 7), and subsequently returned into the initial position, that is, into the third position.
When the pressure detected by the transducers reaches a maximum value, corresponding to an overload pressure produced by an excess of scrap between the rollers 52, 54, the latter are kept in rotation in said pressure condition for a pre-set time, for example 3s, at the end of which the drive pumps are reset to zero according to a pre-set discharge ramp. Then the counter rotation of the rollers 52, 54 (directions F3, F4) is inverted, passing from zero rotation speed to a maximum rotation speed according to a predetermined acceleration ramp, for example gradual.
At the same time the wall 30 moves from the third position to the second or fourth position determining the rending, by means of the hook-type protuberances 40, of that part of the scrap which has caused the overload condition.
At the end of a predetermined interval of time the wall 30 is returned into the third position and the rollers 52, 54 start to rotate again in the fragmentation direction (F1, F2), passing from zero speed to maximum speed according to a pre-set acceleration ramp, causing the scrap thus treated to be crushed and to move toward the discharge exit 24.

Program for the preliminary crushing of loose scrap

The rollers 52, 54 rotate in the normal direction of rotation of fragmentation (F1, F2), the wall 30 is positioned in the inactive position (fig. 4), which is optimal for the treatment of loose scrap.
If, for at least 15s consecutively, or other predetermined interval of time, the pressure values detected by the relative transducers in the hydraulic circuits driving the rollers 52, 54 remain below a set predetermined minimum value, it is probable that there will be a situation of "floating" of the loose scrap introduced. The wall 30 is then moved automatically between the inactive position and the third position, staying in the third position for at least 5s, for example, and then is returned into the initial position, that is, the inactive position.
When the pressure detected by the pressure transducers reaches a maximum value, corresponding to an overload pressure produced by an excess of scrap between the rollers 52, 54, the latter are kept in rotation in said pressure condition for a pre-set time, for example 3s, at the end of which the relative drive pumps are reset to zero according to a pre-set discharge ramp. Then the counter rotation of the rollers 52, 54 (directions F3, F4) is inverted, passing from a zero rotation speed to a maximum rotation speed according to a predetermined acceleration ramp, for example gradual.
At the same time the wall 30 moves from the inactive position to the second or fourth position determining the rending, by means of the hook-type protuberances 40, of that part of the scrap which has caused the overload condition.
At the end of a predetermined interval of time the wall 30 is returned into the first inactive position and the rollers 52, 54 start to rotate again in the fragmentation direction (F1, F2), passing from zero speed to maximum speed according to a pre-set acceleration ramp, causing the scrap thus treated to be crushed and to move toward the discharge exit 24.

Semi-automatic program for scrap in mixed form

The semi-automatic program is controlled and visibly inspected by an operator. The wall 30 is positioned in the inactive position (fig. 4), irrespective of the type of scrap to be treated.
The rollers 52, 54 rotate in the normal fragmentation direction (F1, F2), the wall 30 is positioned in the inactive position. By means of the command panel, for example a radio control, the operator can intervene during the automatic functioning of the rollers 52, 54, at his discretion, by driving the command lever, in order to move the wall 30 manually from the inactive position to the second, third or fourth position, for example in a continuous manner and based on the actual introduction condition of the scrap, so as to prevent possible "floating" conditions. When the operator releases the command lever this determines the automatic return of the wall 30 into the inactive position.
When the pressure detected by the pressure transducers reaches a maximum value, corresponding to an overload pressure produced by an excess of scrap between the rollers 52, 54, the latter are kept in rotation in such said condition for a pre-set time, for example 3s, at the end of which the relative drive pumps are reset to zero according to a pre-set discharge ramp. Then the counter rotation of the rollers 52, 54 (directions F3, F4) is inverted passing from a zero rotation speed to a maximum rotation speed according to a predetermined acceleration ramp, for example gradual.
At the same time the wall 30, without manual intervention by the operator, moves automatically from the inactive position to the second or fourth position determining the rending, by means of the hook-type protuberances 40, of that part of the scrap which has caused the overload condition.
At the end of a predetermined interval of time the wall 30 is returned into the first inactive position and the rollers 52, 54 start to rotate again in the fragmentation direction (F1, F2), passing from zero speed to maximum speed according to a pre-set acceleration ramp, causing the scrap thus treated to be crushed and to move toward the discharge exit 24.
Advantageously, during the execution of the automatic cycles, when a predefined rotation time has passed without any overload conditions occurring, or after a predetermined number of successive overload conditions, the directions of rotation of the rollers 52, 54 are automatically inverted for a predefined interval of time, necessary to carry out any cleaning of possible scrap which has become entrapped.
It is clear that modifications and/or additions of parts and/or steps may be made to the preliminary crushing device 10 and the relative method as described heretofore, without departing from the field and scope of the present invention.
It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of preliminary crushing device, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

Claims

Device for the preliminary crushing of scrap, comprising conveying means (22) and crushing means (50) disposed at a predetermined operating distance from the conveying means (22), said conveying means (22) comprising an introduction portion such as an inclined plane (27), and a pressure element (30) disposed immediately after the introduction portion (27), and provided with hook elements (40), the pressure element (30) being selectively movable between at least a first position in which it is disposed substantially aligned with the introduction portion (27), defining therewith a substantially continuous feed surface on which the scrap (13) is disposed according to a first inclination, and a second position in which it protrudes forward with respect to the introduction portion (27) so as to bring its hook portions (40) closer to the crushing means (50), characterized in that the pressure element (30) has at least a third position in which at least its upper end is disposed in a recessed manner with respect to the lower end of the introduction portion (27), so as to determine between them a step (28) to increase, at least temporarily, the operating distance between the crushing means (50) and the hook portions (40), and to modify the inclination of the scrap (13) on the feed surface with respect to at least the crushing means (50).
Device as in claim 1, characterized in that the crushing means (50) comprise at least two counter-rotating rollers, an upper crushing roller (52), or low-speed roller, and a lower roller (54), or high-speed roller, both provided with toothed profiles (58) cooperating with each other during crushing.
Device as in claim 2, characterized in that the crushing rollers (52, 54) can be driven independently from one another through corresponding motor means.
Device as in claim 2 or 3, characterized in that the crushing rollers (52, 54) rotate according to a predetermined speed ratio, said speed ratio being at least 1:3.
Device as in any claim hereinbefore, characterized in that the hook portions (40) are disposed parallel to the toothed profiles (58) in the direction of feed of the scrap in a substantially intermediate position between one toothed profile (58) and the other.
Device as in any claim hereinbefore, characterized in that it comprises signaling means able to provide indications on its functional state, in order to signal blockage or overload situations of the crushing means (50).
Method for the preliminary crushing of scrap in which, by means of conveying means, the scrap is made to advance toward crushing means (50) disposed at a predetermined operating distance from the conveying means, said conveying means comprising an introduction portion (27) and a pressure element (30), disposed immediately after the introduction portion (27), provided with hook portions (40) and wherein the pressure element (30) is selectively movable between at least a first position, in which it is disposed substantially aligned with the introduction portion (27), defining therewith a substantially continuous feed surface on which the scrap (13) is disposed according to a first inclination, and a second position, in which it protrudes with respect to the introduction portion (27) so as to bring the hook portions (40) closer to the crushing means (50), characterized in that the pressure element (30) is moved to at least a third position in which at least its upper end is disposed in a recessed manner with respect to the lower end of the introduction portion (27), so as to determine a step (28) to increase, at least temporarily, the operating distance between the crushing means (50) and the hook portions (40) and to modify the inclination of the scrap (13) on the feed surface with respect to at least the crushing means (50).
Method as in claim 7, characterized in that the crushing means (50) comprise at least two counter-rotating rollers, an upper crushing roller (52), or low-speed roller, and a lower roller (54), or high-speed roller, both provided with toothed profiles (58) cooperating with each other during crushing.
Method as in claim 8, characterized in that the crushing rollers (52, 54) are driven independently from one another by means of corresponding motor means.
Method as in claim 8 or 9, characterized in that said crushing rollers (52, 54) are made to rotate according to a predetermined speed ratio, said speed ratio being at least 1:3.
Method as in any claim from 7 to 10, characterized in that automatic or partially automatic work cycles are provided according to the type of scrap that introduced, either loose or in packed form.