Crushing hammer

Abstract

Crushing hammer (10) comprising at least one central body (11) defining a longitudinal median plane (P1) and configured to be inserted longitudinally in a rotor (110), so that said median plane (P1) is radial to said rotor (110), and at least one shaped head (12) extending integrally from said central body (11) lying on said median plane (P1); the central body (11) comprises two shoulders (13) obtained opposite to said median plane (P1) and defining a first transverse thickness (S1), said shaped head (12) comprising two side surfaces (14, 15) obtained opposite to said median plane (P1) and defining a second transverse thickness (S2), greater than or equal to said first transverse thickness (S1).

Description

[0001] "CRUSHING HAMMER"

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a crushing hammer, known by the English term of "blow bar", used in an impact crusher, of the type used for the crushing of mineral agglomerates, typically used in the construction field, in order to reduce the size, until a product is obtained, intended for final disposal, or for recycling to obtain new products.

[0004] BACKGROUND OF THE INVENTION

[0005] Impact crushers are known, used for crushing construction products in mineral agglomerate such as concrete, cement, asphalt or others.

[0006] Known impact crushers typically comprise a hopper, through which a rotor is fed, in turn radially provided with multiple crushing hammers. The joint rotation of the hammers with the rotor implements an impact action against the fed mineral agglomerates, which are partly crushed and, on the other hand, thrown against impact plates, or armour-plates, facing the rotor circumferentially. The repeated impact action both against the hammers and against the impact plates, determines a progressive reduction of the size of the mineral agglomerates, until a desired dimensional value is reached, and they fall by gravity below the crusher.

[0007] Given the mechanical action with a violent impact, the crushing hammers are one of the most stressed parts of the system, as well as the one most subject to wear. Furthermore, since the crushing hammers are the active part in the crushing action, both the quality of the crushing carried out and the operational effectiveness, stresses and wear of the passive crushing components, such as the impact plates, are directly determined by them.

[0008] It is known that to improve the effectiveness and durability of the crushing hammers, but also of the auxiliary components, different solutions have been proposed, arriving at a common embodiment, in which the hammers are configured in bars inserted longitudinally into the rotors and provided at the ends with shaped heads that, in operating condition, protrude radially from the rotors themselves.

[0009] These bars can have two opposite shaped heads, which are alternately arranged in operating condition, so as to allow a functional replacement of the hammers by only inverting the bar with respect to the rotor. Usually, there are four crushing hammers for each rotor, angularly equidistant from each other. More extreme operational solutions provide for an opposite circumferential alternation of two crushing hammers with reduced head, also called dummy hammers, or short hammers, and two crushing hammers arranged with new heads, so as to increase the volume of building material subjected to crushing without compromising the balance of the rotor.

[0010] A typical conformation of the hammers substantially provides that the bar, in addition to the two shaped heads at the ends, has a central body obtained integrally in an intermediate position to the two heads, and shaped to be inserted longitudinally into the rotor.

[0011] In these known solutions, each head is offset and opposite with respect to the other, with reference to a median plane of the hammer, and has a rectangular section with side surfaces parallel to each other, to define a constant thickness on the long side of the head itself.

[0012] For structural reasons, the central body is designed with a thickness not less than the thickness defined by the side surfaces of the heads. In this sense, some known solutions provide for an increase in the thickness of the central body by a few percentage points higher than the thickness defined by the heads. In other words, the thickness of the central body is always greater than the thickness of the heads.

[0013] However, these manufacturing geometries have structural limits, in particular when made with materials other than traditional manganese steels, for example in cast iron, in martensitic steels, or with a high concentration of chromium, in which it is necessary to provide larger ceramic reinforcement inserts for the heads.

[0014] In addition, especially in use at high rotational speeds and with the solutions of alternating hammers with worn heads and new heads, the geometries of the traditional hammers are subject to frequent fatigue fractures, especially in the connection areas between the central body and the head, as well as the formation of cracks, which can develop even during the subsequent use of the other head of the same hammer.

[0015] A further drawback of the known solutions is the fact that the parallelism of the side surfaces of each head causes that, during the impact phase during the rotation, the partially crushed material is mainly projected towards the bottom of the impact plates, i.e. substantially following the direction of rotation of the rotor. This particular kinematics on the one hand causes stranding, overloading and breakage of the parts and, on the other hand, involves extra wear on the lower part of the impact plates, leaving the upper part substantially intact. This means that there is a consequent increase in the operating costs and a reduction in the productivity of the crusher.

[0016] There is therefore the need to perfect a crushing hammer that can overcome at least one of the disadvantages of the state of the art.

[0017] To do this, it is necessary to solve the technical problem of making the crushing hammer more robust.

[0018] In particular, one purpose of the present invention is to provide a crushing hammer that enables the limiting of fatigue fractures, especially in the connection areas between the central body and the head, as well as the formation of cracks, even in use at high rotation speeds and with alternating hammer solutions.

[0019] Another purpose of the present invention is to provide a crushing hammer with a geometry suitable for casting in materials other than manganese steels, i.e. being able to provide larger ceramic reinforcement inserts for the heads.

[0020] A further purpose of the present invention is to provide a crushing hammer that allows both an effective crushing of the building material and a substantially uniform wear of the impact plates, limiting the operating costs and reducing the productivity of the crusher.

[0021] 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.

[0022] SUMMARY OF THE INVENTION

[0023] The present invention is set forth and characterized in the independent claim. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

[0024] In accordance with the above purposes, and to resolve the technical problem disclosed above in a new and original way, also achieving considerable advantages compared to the state of the prior art, a crushing hammer according to the present invention is applied in an impact crusher, of the type used for crushing mineral agglomerates, typically used in construction, so as to reduce their size.

[0025] In particular, the crushing hammer according to the present invention comprises at least one central body, for example of the type shaped to be housed longitudinally in a rotor of the impact crusher, which central body defines a longitudinal median plane which, in use, is radial to the rotor.

[0026] Furthermore, the crushing hammer comprises at least one shaped head, advantageously two opposite ones, which extend(s) integrally from the central body, lying in the median plane. The shaped heads, when rotated by the rotor, carry out the active action of beating and breaking the mineral agglomerates, throwing the latter onto passive elements of the impact crusher, such as the impact plates, or armour-plates, circumferentially opposite to the rotor.

[0027] In accordance with one aspect of the present invention, the central body comprises two shoulders obtained opposite to the median plane and spaced apart from each other by a first transverse thickness, while the shaped head has two side surfaces, which are obtained opposite to the median plane and define a second transverse thickness, greater than or equal to the first transverse thickness, so as to confer greater strength to the crushing hammer itself, compared to known solutions, in which the thickness of the shaped head is, instead, smaller than the thickness of the central body. Advantageously, in the solution according to the present invention, the increase of the second transverse thickness can be comprised in a percentage chosen between about 10% and about 20%, with respect to the first transverse thickness.

[0028] This at least has the advantage of making a crushing hammer which, being increased in its active beating part, i.e. in the shaped head, makes it possible to limit fatigue fractures, especially in the connection areas between the central body and the head, as well as crack formation, even in use at high rotational speeds and with alternating hammer solutions.

[0029] This same solution, according to the present invention, gives the crushing hammer a geometry more suitable for casting in materials other than manganese steels, since, as the shaping head has a greater thickness compared to the central body, it is more suitable for the internal housing of ceramic inserts, to reinforce the heads, of greater dimensions, as required, precisely, in cast iron, martensitic steel, high chrome, or other constructions.

[0030] In accordance with another aspect of the present invention, the two side surfaces are connected to each other by an outer surface and a first one of the two side surfaces is inclined at a certain angle with respect to the median plane, in the direction of the outer surface itself In other words, the first side surface substantially forms an obtuse angle with the upper surface, net of the necessary demolding inclinations of the latter. In preferred solutions, the angle thus formed has an amplitude of between about 0.5° and about 10°, advantageously between about 1.5° and about 5°.

[0031] As a result of this inclination, during the rotation of the rotor the mineral agglomerates that are hit by the first surface do not necessarily follow the direction of rotation downwards, but also bounce with trajectories tending upwards, involving the impact plates substantially in all their parts.

[0032] Therefore, in addition to allowing an effective crushing of the building material, a substantially uniform wear of the impact plates is defined, limiting operating costs and reducing the productivity of the crusher.

[0033] In accordance with another aspect of the present invention, the second one of the two side surfaces is substantially parallel to the median plane, and defines a diverter fitting with the outer surface. Advantageously, this diverter fitting is configured to define a radius of the order of tens of millimetres, for example between about 15mm and about 25mm, but also higher.

[0034] This radius allows the shaped head to better distribute the impacts accidentally caused by the mineral agglomerates being treated, especially in operational solutions with alternating hammers, thus limiting the formation of cracks that can compromise the structure and correct operation of the crushing hammer.

[0035] In accordance with a further aspect of the present invention, the shaped head can be obtained offset with respect to the central body, in a transverse direction with respect to the median plane. In this embodiment, the first side surface may face in the direction of the offset.

[0036] DESCRIPTION OF THE DRAWINGS

[0037] These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

[0038] - fig. 1 is a schematic cross-sectional view of an impact crusher to which crushing hammers are applied, according to the present invention;

[0039] - fig. 2 is a schematic view of the application variant of fig. 1 ; - fig. 3 is a schematic cross-sectional view of a first embodiment of a crushing hammer according to the present invention; and

[0040] - fig. 4 is a schematic cross-sectional view of a second embodiment of a crushing hammer according to the present invention;

[0041] We must clarify that in the present description the phraseology and terminology used, as well as the figures in the attached drawings also as described, have the sole function of better illustrating and explaining the present invention, their function being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

[0042] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications. DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

[0043] With reference to the attached figures, a crushing hammer 10 (figs. 3 and 4) according to the present invention is applied in an impact crusher 100 (figs. 1 and 2) used for the crushing of mineral agglomerates 500 of various sizes, for example of the type coming from construction disposal such as cement, asphalt or other, up to a desired maximum size. The impact crusher 100 is of the type provided with a rotor 110 arranged to be axially rotatable inside a crushing chamber 120, the latter defined, on at least one side coordinated to the direction of rotation, by one or more plates, or impact armour-plates 130. A hopper 140 faces the crushing chamber 120 to gravitationally feed the mineral agglomerates 500.

[0044] In this conformation of the impact crusher 100, the crushing hammers 10 according to the present invention are housed longitudinally to the rotor 110, so as to radially protrude from the latter and carry out an active impact action on the mineral agglomerates 500, which are, in part, directly crushed and, in another part, thrown against the impact armour-plates 130, which in turn carry out a passive crushing action.

[0045] The continuous rotation of the rotor 110, with the consequent active and passive impact and crushing action exerted by the crushing hammers 10 and the impact armour-plates 130, progressively reduces the dimensions of the mineral agglomerates 500, until reaching a desired size, such as to cross the distance defined between the rotor 110 and the impact armour-plates 130, in the exit zone of the crushing chamber 120.

[0046] The crushing hammer 10 is applied with the same effectiveness and with the advantages provided by the solution according to the present invention, both in a traditional solution (fig. 1), in which four angularly offset crushing hammers 10 are mounted on the rotor 110, uniformly with each other and arranged in an effective operating condition for crushing, and in a more advanced solution (fig. 2) in which four crushing hammers 10 are always mounted on the rotor 110, but two in an effective operating condition and two, alternating, which can be both in a worn and ineffective condition for crushing, and provided with a reduced head, also called dummy hammers, in any case shorter than the other two.

[0047] With reference to the embodiment illustrated in fig. 3, the crushing hammer 10 substantially comprises a central body 11 with longitudinal extension, and two shaped heads 12, obtained integrally and in transverse continuity to the central body 11 and having substantially the same longitudinal extension of the latter.

[0048] The central body 11 defines a longitudinal median plane Pl and comprises two shoulders 13, which are obtained opposite, though inclined and not mirror-image, with respect to the median plane Pl. The shoulders 13 are configured to be inserted in relative longitudinal seats of the rotor 110, such that the median plane Pl is radial with respect to the rotor 110.

[0049] The distance between the two shoulders 13 defines a first transverse thickness S 1, which acts as a resistant core in the operating condition of the crushing hammer 10, when mounted on the rotor 110. Advantageously, the first transverse thickness SI has a value ranging between about 95mm and about 105mm. This size makes it possible, under normal and expected conditions of use, to guarantee the desired mechanical resistance to the stresses involved, substantially without compromising the operating quality of the crushing hammer 10.

[0050] In the embodiments shown in the attached figures, the two shoulders 13 are substantially parallel to each other and define an offset angle 0 with the median plane Pl. This offset angle 0 is advantageously comprised between about 10° and about 20°, and defines an opposite offset of the two shaped heads 12 with respect to the median plane Pl. In fact, since the shaped heads 12 are obtained by casting with surfaces that are unfinished, or ground, or machined mechanically, and in continuity transverse to the central body 11, due to the inclination of the two shoulders 13 they are configured misaligned to the median plane Pl.

[0051] Each shaped head 12 comprises a first side surface, or front surface 14, obtained inclined and substantially continuous, with respect to one of the two shoulders 13, a second side surface, or rear surface 15, obtained inclined and substantially continuous with respect to the other of the two shoulders 13 and opposite the front surface 14, with respect to the median plane Pl, and an outer surface 16, connecting the front surface 14 and the rear surface 15.

[0052] The distance provided between the front surface 14 and the rear surface 15 defines a second transverse thickness S2, of dimension greater than or equal to the first transverse thickness SI, so as to act as a crushing body. Advantageously, the second transverse thickness S2 has a percentage of dimensional increase that is between about 10% and about 20%, with respect to the first transverse thickness SI, so that it can also accommodate increased ceramic inserts, of substantially known type and not shown in the figures, which increase the wear resistance and therefore the duration of the casting, particularly in the case of making the crushing hammer 10 with martensitic steels, or others.

[0053] Each shaped head 12 also comprises a stop rib 18 obtained protruding from the rear surface 15 and configured to be arranged, in use, in contact with the coordinated seat provided in the rotor 110, so as to transmit to the crushing hammer 10, the rotary motion of the rotor 110 itself.

[0054] In addition, a housing surface 19 is provided between the front surface 14 and the relative shoulder 13, which cooperates with the rotor 110 to prevent accidental radial extraction of the crushing hammer 10 from the rotor 110 itself, due to the centrifugal action given by the rotation of the masses.

[0055] In the embodiment illustrated in fig. 3, the front surface 14 and the rear surface 15 are substantially parallel to each other and to the median plane Pl, and define with the outer surface 16 substantially right angles, net of the necessary demolding inclinations of the latter.

[0056] Between the rear surface 15 and the outer surface 16 a diverter fitting 17 is obtained, advantageously already in the casting, which is shaped to better distribute the impacts accidentally caused by the mineral agglomerates 500, especially in the operating solutions of the type shown in fig. 2, in which the mineral agglomerates 500 have more space to move between one crushing hammer 10 and the other, and therefore greater inertia of impact on the relative shaped heads 12.

[0057] In particular, the diverter fitting 17 provides a radius of the order of tens of millimetres, for example between about 15mm and about 25mm, advantageously about 20mm, which represents an advantageous compromise between increasing the distribution surface of the accidental impact and reducing the resistant mass of the relative shaped head 12.

[0058] In the embodiment illustrated in fig. 4, the rear surface 15 remains substantially parallel to the median plane Pl, while the front surface 14 is inclined by a certain angle a open in the direction of the outer surface 16, so that the front surface 14 defines with the latter a substantially obtuse angle, net of the demoldings.

[0059] The angle a has a particular operational effectiveness with an amplitude comprised between about 0.5° and about 10°, advantageously between about 1.5° and about 5°. This angle, although relatively small, allows the mineral agglomerates 500 to rebound in a direction different from the rotational tangency, when hit by the shaped head 12, thus substantially affecting the entire passive impact area defined by the impact armour-plates 130.

[0060] It is clear that modifications and / or additions of parts may be made to the crushing hammer 10 described heretofore, without departing from the field and scope of the present invention, as defined by the claims.

[0061] 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 other equivalent forms of crushing hammer, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

[0062] In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by the claims.

Claims

CLAIMS1. Crushing hammer (10) comprising at least one central body (11) defining a longitudinal median plane (Pl) and configured to be inserted longitudinally in a rotor (110), so that said median plane (Pl) is radial to said rotor (110), and at least one shaped head (12) extending integrally from said central body (11) lying on said median plane (Pl), characterized in that said central body (11) comprises two shoulders (13) obtained opposite to said median plane (Pl) and defining a first transverse thickness (SI), said shaped head (12) comprising two side surfaces (14, 15) obtained opposite to said median plane (Pl) and defining a second transverse thickness (S2), greater than or equal to said first transverse thickness (SI).

2. Crushing hammer (10) as in claim 1, characterized in that said second transverse thickness (S2) is greater than a percentage between about 10% and about 20% with respect to said first transverse thickness (S 1).

3. Crushing hammer (10) as in any claim hereinbefore, wherein said two side surfaces (14, 15) are connected to each other by an outer surface (16), characterized in that at least a first side surface (14) of said two side surfaces (14, 15) is inclined by a certain angle (a), with respect to said median plane (Pl), in the direction of said outer surface (16).

4. Crushing hammer (10) as in claim 3, characterized in that said angle (a) has an amplitude between about 0.5° and about 10°.

5. Crushing hammer (10) as in claim 4, characterized in that said angle (a) has an amplitude between about 1.5° and about 5°.

6. Crushing hammer (10) as in any claim hereinbefore from 3 onwards, characterized in that at least a second side surface (15) of said two side surfaces (14, 15) is substantially parallel with respect to said median plane (Pl).

7. Crushing hammer (10) as in claim 6, characterized in that it comprises at least one diverter fitting (17) obtained between said second side surface (15) and said outer surface (16) and configured to define a radius of the order of tens of millimetres.

8. Crushing hammer (10) as in any claim hereinbefore, characterized in that said shaped head (12) is obtained offset with respect to said central body (11), in a transverse direction with respect to said median plane (Pl).

9. Crushing hammer (10) as in claim 8 when dependent on 3, characterized in that said first side surface (14) faces in the direction of the offset of said shaped head (12) with respect to said central body (11).

10. Crushing hammer (10) as in any claim hereinbefore, characterized in that it comprises two shaped heads (12) extending integrally and on opposite sides from said central body (11), both lying on said median plane (Pl).

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