Abstract:
A beater bar for a rock impact crusher, in particular a rotary impact crusher, including a carrier which, in the region of a cutting edge, has a plurality of cutting elements made of a hard material arranged next to one another. For the purpose of simple maintenance and for improved cost-effectiveness of the beater bar, according to this invention two or more cutting elements are fastened on a cutting-element holder, and two or more cutting-element holders can be interchangeably fastened to the carrier.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a blow bar for an impact crusher, in particular a rotary impact crusher, having a carrier, which, in a region of a cutting edge, has a plurality of cutting elements made of hard material arranged next to one another. 
         [0003]    2. Discussion of Related Art 
         [0004]    European Patent Reference EP 0 581 758 B1 discloses a rotary impact crusher equipped with several blow bars. The blow bar includes a carrier that can be clamped by a wedge clamp to an anchoring attachment to permit the blow bar to be interchangeably affixed to the rotor of a rotary impact crusher. The carrier has a seating surface facing in the tool-advancing direction onto which a plurality of cutting elements are placed and can be lined up in a longitudinal direction of the blow bar. The cutting elements are first placed loosely onto the carrier. As soon as the wedge connection is clamped, then the cutting elements are affixed to the carrier in captive fashion. If one or more of the cutting elements becomes worn, then the clamped connection must be released. Then the respective cutting elements can be replaced with non-worn cutting elements. This known type of fixing the cutting elements to the carrier has turned out to be unsuitable in actual practice. In particular, when the blow bar to be serviced is in a lower position of the rotor, after the clamped connection is released, the cutting elements can fall in an uncontrolled fashion and must then be laboriously collected and placed onto the carrier. Furthermore, the contact surfaces of the carrier and cutting elements must be very precisely matched to one another in order to enable a gap-free connection. Because the cutting elements, which are embodied as sintered components, can only be produced within a certain tolerance range, the gap-free association with the carrier can never be completely guaranteed, leading to frequent breakage of cutting elements. 
         [0005]    German Patent Reference DE 23 43 691 discloses another blow bar having three hard metal plates fastened to a carrier. Here, a screw connection is used to clamp the hard metal plates into recesses in the carrier. German Patent Reference DE 295 21 050 U1 discloses a similar arrangement in which the carrier of the blow bar has a dovetail-shaped groove into which a dovetail-shaped insertion lug of the bar-shaped cutting element is slid. In blow bars of this type, there is frequently the danger that powerful impact stress results in bar breakage. Then, the entire cutting element must be expensively replaced. 
         [0006]    German Patent Reference DE 16 58 400 U1 discloses another blow bar in which a hard metal block extending the entire width of the blow bar is soldered to the carrier. 
       SUMMARY OF THE INVENTION 
       [0007]    One object of this invention is to provide a rugged blow bar that is easy to service. 
         [0008]    This object of this invention is attained with two or more cutting elements fastened on a cutting element holder so that it is possible to interchangeably fasten two or more cutting element holders to the carrier. 
         [0009]    Two or more cutting element holders are thus built into the unit to produce the cutting edge and in turn carry two or more cutting elements. The cutting element holders thus form or constitute individually manipulable subassemblies that can be securely installed on the carrier in a short amount of time in order to produce the cutting edge. If abrasion has caused the cutting element to reach its wear limit, then the cutting element holder that carries this cutting element can be removed and replaced independently of the other cutting element holders. This permits the maintenance to be carried out in a time-optimized, economical, and reliable fashion. 
         [0010]    In one embodiment of this invention, the cutting elements are integrally joined to the cutting element holder, preferably soldered. This achieves a gap-free, non-breakage-prone association or connection between the cutting elements and the cutting element holder. 
         [0011]    In one embodiment of this invention, the carrier has a recess with a supporting surface and a bearing surface at an angle thereto, with the supporting surface facing in the tool-advancing direction, the cutting element holder is supported on this supporting surface by a contact surface facing away from the tool-advancing direction, and a bottom adjoining the contact surface of the cutting element holder rests against the supporting surface over a large area. This invention recognizes that during the tool engagement, there is a varying course of the force. The supporting surface and the bearing surface reliably intercept these machining forces and divert them into the carrier, so that the cutting element holder is always securely fixed. 
         [0012]    In another embodiment of this invention, the cutting element holder is connected to the carrier by at least one fastening lug, which is inserted into a fastening socket and the fastening lug has a threaded opening that is flush with a screw opening that feeds into the fastening socket. The fastening lug can be disposed on the cutting element holder and the fastening socket can be disposed on the carrier, or vice versa. When transverse forces occur, the fastening lug is supported in the fastening socket and carries the forces past or beyond this supporting region. Thus the fastening screws, which connect the cutting element holder to the carrier, are kept fee of transverse forces. With this simple provision, a markedly improved diversion of force is possible. 
         [0013]    If it is possible to position the cutting element holders in a preassembly position on the carrier in which they are adjustable relative to one another, then the cutting element holders in the preassembly position can be pushed against one another without play and then finally fixed in position. As a result, the cutting elements can be pushed against one another without play, and thus in the connection points during tool use, no harmful transverse forces can become operative. 
         [0014]    In this embodiment, for example, a blow bar of this invention provides the fastening lug inserted with play into the fastening socket, and when the connection, preferably a threaded connection, is released, the cutting element holder is adjustable to a limited degree in the longitudinal direction of the cutting edges. 
         [0015]    If the carrier has screw openings that are let into the carrier from the rear facing away from the tool-advancing direction and fastening screws are inserted through the screw openings and screwed into the cutting element holder, then the screw head is positioned on the back side of the carrier in a wear-protected fashion. Then, if needed, the fastening screw can always be reliably loosened. If the fastening screw is screwed into a threaded opening in the form of a blind hole in the cutting element holder, then the threaded opening is accommodated in a protected fashion as well, and no crushed material that would block the threaded connection can penetrate into the threaded region. 
         [0016]    To minimize carrier wear, one embodiment of this invention provides that at the radially outer end facing away from the tool-advancing direction, the cutting element holder has a chip-diverting surface that transitions in a flush manner into a diverting surface of the carrier. Thus, the carrier is covered by the cutting element holder and is protected against the rock material to be crushed. 
         [0017]    A blow bar according to this invention can be arranged to that transversely to the tool-advancing direction, the cutting element holder is adjoined by a front surface of a base part of the carrier and that an impact rocker is attached to the base part, facing away from the cutting insert. By equipping the blow bar with cutting elements according to this invention, wear in the vicinity of the cutting edge is initially optimized. As a result, reduced wear to the impact rocker then surprisingly ensues. 
         [0018]    One object of this invention is also attained with a cutting insert for a blow bar, having a cutting element holder to which a plurality of cutting elements made of hard material are attached, in which the cutting elements are arranged next to one another transversely to the tool-advancing direction and form a cutting edge. In this embodiment, the cutting element holder has a rear contact surface facing away from the tool-advancing direction, from which a fastening lug integrally formed onto the cutting element holder protrudes. This fastening lug is preferably provided with a threaded opening. This cutting insert can be built easily and quickly onto a carrier of a blow bar. Thus, the cutting insert need merely be inserted by its integrally formed-on fastening lugs in fastening sockets, provided for them, in the carrier. The cutting insert can then be screwed to the carrier via the threaded openings in the fastening lug. The fastening lugs keep the fastening screws free from transverse forces exerted during tool use. Thus stable coupling of the cutting insert to the carrier is realized. In the event of damage, the cutting insert can easily be replaced by undoing the threaded connections and then removing the cutting element holder from the carrier. It can then be replaced with a new, unworn cutting insert. 
         [0019]    The fastening lug can be manufactured simply and dimensionally precisely if it has a square or rectangular geometry in cross-section. 
         [0020]    Preferably, the central longitudinal axis of the threaded opening extends vertically relative to the contact surface so that the forces induced by the fastening screw are transferred directly into the contact surface. It has been demonstrated that a very stable coupling of the cutting insert, without the risk of breakage, is possible as a result. 
         [0021]    One embodiment of a cutting insert includes the cutting element holder having a bottom that adjoins the contact surface at right angles to it. By the bottom and the contact surface, the cutting insert can be optimally supported on corresponding bearing surfaces. 
         [0022]    If the cutting element holder has a seating surface, which is inclined away from the tool-advancing direction and to which the cutting elements are coupled over a large area by a supporting section, then a geometry of the cutting element holder that is easy to manufacture is possible, and the inclined seating surface optimally takes into account the varying course of the force during tool engagement and thus serves to brace the cutting element reliably. The cutting element can in particular be soldered to the seating surface, to ensure a play-free connection. 
         [0023]    Another wear protection of the cutting insert can be produced so that the cutting element holder has a receiving region in which a plurality of wear plates made of hard material are lined up in the longitudinal direction of the cutting insert and the wear plates, adjoin the cutting elements directly. Because a plurality of wear plates are used, a segmented structure is produced, which results in a significantly reduced risk of breakage for the wear plates. The lining up of the wear plates, which should in particular be free of gaps, prevents the wear plates from being subjected to undue transverse forces, which could break them. Because the wear plates directly adjoin the cutting elements, this prevents the wear plates from eroding the region under the cutting elements. 
         [0024]    In this case, it can be advantageous for two wear plates per cutting element to be installed and for the cutting elements to have double the width of the wear plates in the longitudinal direction of the cutting insert. 
         [0025]    A cutting insert according to this invention can have the cutting elements triangular in cross-section and can have an impact surface facing in the tool-advancing direction and at an angle thereto have a free surface facing away from the tool-advancing direction. The free surface and the advancing normal oriented in the tool-advancing direction enclose a free angle so that the free surface slopes downward from the cutting edge in the direction opposite the tool-advancing direction. This design produces a self-sharpening geometry for the cutting element. As a result, when an abrasion-induced wear of the cutting elements occurs, a sharp-edged cutting is retained. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    This invention is explained in greater detail in view of an exemplary embodiment shown in the drawings, wherein: 
           [0027]      FIG. 1  shows a blow bar in perspective in a side view; 
           [0028]      FIG. 2  shows the blow bar of  FIG. 1  in perspective in a rear view; 
           [0029]      FIG. 3  shows a cutter insert, which can be built into the blow bar of  FIGS. 1 and 2 , in a fragmentary perspective view; 
           [0030]      FIG. 4  shows the cutting insert of  FIG. 3  in a side view; 
           [0031]      FIG. 5  shows the cutting insert of  FIG. 4  in a front view; and 
           [0032]      FIG. 6  shows the cutting insert of  FIGS. 3-5  in perspective in a rear view. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]      FIG. 1  shows a blow bar, which has a carrier  10 . The carrier  10  has a base part  11 , which forms a front face  12  pointing in the tool-advancing direction (V). The base part  11  is adjoined laterally by a lower part  13 , and the impact rocker  13  has an upper face oriented toward the front face  12 . Facing away from the impact rocker  13 , the base part  11  has a lug, into which a recess  18  in the form of a milled-out area is machined. The recess  18  forms a supporting surface  18 . 2  and a bearing surface  18 . 1  at an angle to it. The supporting surface  18 . 2  pointing in the tool-advancing direction (V) transitions to a diverting surface  19 . On the back, the carrier  10  has protrusions  15 , which are used for fixing a rotor of a rotary impact crusher. On both sides of the protrusions  15 , supporting surfaces  14  are provided. In the vicinity of or near the impact rocker  13 , the carrier  10  forms a seating surface  17 . This face is disposed at an angle to the supporting surface  14  on the back. By means of or with the supporting surface  14  and the seating surface  17 , the carrier  10  can be reliably supported on the rotor. As shown in  FIG. 1 , four cutting inserts  20  are built into the recess  18 , which are disposed side by side in the longitudinal direction of the carrier  10 . 
         [0034]      FIG. 2  shows the arrangement of  FIG. 1  in perspective in a rear view. As shown in this view, three protrusions  15  which are separated from one another by grooves are integrally formed onto the base part  11  on the back. Beginning at the back side of the carrier  10 , fastening sockets  16  in the form of bores are made in the carrier  10 . These bores open in the bearing surface  18 . 2  of the recess  18 . Fastening screws  16 . 1  can be passed through the fastening socket  16  and screwed into the cutting inserts  20 , as will be explained hereinafter. 
         [0035]    As shown in  FIG. 3 , the cutting insert  20  includes a cutting element holder  21 , on which cutting elements  23  and wear plates  22  are fastened. The cutting element holder  21  has a vertical contact surface  21 . 8 , which is adjoined by a bottom  21 . 1  via a chamfer  21 . 10 . In the assembled state, the bottom  21 . 1  is supported on the bearing surface  18 . 1  of the carrier  10 , and the contact surface  21 . 8  is supported on the supporting surface  18 . 2 . The chamfer  21 . 10  guarantees reliable contact with the supporting surface  18 . 2  and bearing surfaces  18 . 1 . At the front, the bottom  21 . 1  transitions to a diagonally extending transitional portion  21 . 2 . The transitional portion  21 . 2  is adjoined by a front face  21 . 3 , which is positioned at an angle greater than 90° relative to the bottom  21 . 1  extending in the tool-advancing direction. This positioning angle is preferably selected within the range between 95° and 120°, to make possible a geometry that is favorable from the standpoint of wear. Above the front face  21 . 3  is an adjoining milled-out area  21 . 5  into which the wear plates  22  are inserted. The milled-out area  21 . 5  is dimensioned so that the surfaces of the wear plates  22  transition flush to the front face  21 . 3 . The milled-out area forms a contact surface  21 . 4  with which the wear plates  22  can be aligned. As a result, simpler manufacture is possible. The wear plates  22  are firmly soldered in the milled-out area  21 . 5  on the back by hard solder. 
         [0036]    The milled-out area  21 . 5  is adjoined by a seating surface  21 . 6 . This seating surface  21 . 6  is inclined counter to the tool-advancing direction V and toward the back side of the cutting insert  20 . The cutting element  23  can be firmly soldered to the seating surface  21 . 6  with a flat supporting portion  23 . 5 . The cutting element  23  is dimensioned so that with a protrusion  23 . 4  on its underside, it covers the face end, oriented toward it, of the wear plate  22 , and an impact surface  23 . 3  on the front transitions flush to the front side of the wear plates  22 . This gapless, flush transition prevents crushed material from penetrating and exerting impermissible shear forces on the cutting elements  23  and the wear plates  22 . These shear forces would expose the hard-metal wear plates  22  and cutting elements  23  to the risk of breakage. The impact surface  23 . 3  extends in inclined fashion and points in the tool-advancing direction V. With a free surface  23 . 1 , the impact surface  23 . 3  forms an angle of less than 90°, and in the transition region between the free surface  23 . 1  and the impact surface  23 . 3 , a cutting edge  23 . 2  is formed. The free surface  23 . 1  in turn transitions flush to a diverting surface  21 . 7  of the cutting element holder  21 . 
         [0037]      FIG. 4  shows that the cutting elements  23  are provided laterally with side surfaces  23 . 5  that extend in the tool-advancing direction V. Via these side surfaces  23 . 5 , the cutting elements  23  can be lined up with one another in gapless, flush fashion. Per cutting element  23 , two wear plates  22  each are built in, and the two wear plates  22  have a total width that is equivalent to the width of the cutting element  23 . 
         [0038]    As shown in  FIG. 5 , preferably eight cutting elements  23  are fastened to one cutting element holder  21 . Accordingly, sixteen wear plates  22  are used. 
         [0039]    It shown in  FIGS. 4 and 5  that on the back side of the cutting element holder  21 , three fastening lugs  21 . 9  protrude past or beyond the contact surface  21 . 8 . The fastening lugs are embodied with a square cross section and are penetrated by a blind-bore-like threaded opening  24 , as shown particularly in  FIG. 4 . The threaded opening  24  terminates behind the wear plates  22  in the cutting element holder  21 . The threaded opening  24  has a center longitudinal axis M which can be disposed or positioned in alignment with the fastening socket  16  of the carrier  10 . With the cutting insert  20 , the carrier  10  here has three recesses, which have a cross-sectional shape corresponding to the fastening lugs  21 . 9 . The internal dimensions of these recesses are selected to be slightly larger than the external dimensions of the fastening lug  21 . 9 . In this way, play is created, which enables a limited adjustment of the cutting insert  20  relative to the carrier  10 , when the cutting insert  20  is in an unfixed preassembly position. 
         [0040]      FIG. 4  also shows that the diverting surface  21 . 7  transitions flush to the free surface  23 . 1 . Beginning at the cutting edge  23 . 2 , the free surface  23 . 1  is inclined counter to the tool-advancing direction and at an angle α to the advancement normal extending in the tool-advancing direction V. In this way, a self-sharpening geometry is ensured, which maintains the functionality of the sharp-edged cutting edge  23 . 2 . 
         [0041]    For assembling the cutting inserts  20 , they are inserted by their fastening lugs  21 . 9  into the corresponding recesses  18  in the carrier  10 . Next, from the back side of the carrier  10 , the fastening screws  16 . 1  are passed through the fastening sockets  16  and screwed into the threaded opening  24  in the cutting element holder  21 . At this time the fastening screws  16 . 1  have not yet been tightened, so that the cutting inserts  20  are in a preassembly position. Next, the cutting inserts  20  are pushed against one another in the longitudinal direction L, as shown in  FIG. 5 , of the cutting inserts  20  on the supporting surface  18 . 2  and the bearing surface  18 . 1 , so that they contact one another in gapless fashion. The displacement motion is enabled by the play between the fastening lugs  21 . 9  and the recesses in the carrier  10 . Once the cutting inserts  20  have been pushed against one another, the fastening screws  16  can be tightened with the prescribed torque, and the cutting inserts  20  are then securely fastened to the carrier  10 . 
         [0042]    During operational use, wear to the cutting edge  23 . 2  of the cutting elements  23  occurs because of the contact with the rock materials that are to be crushed. In the process, the cutting elements  23  become worn in the vertical direction, such as transversely to the tool-advancing direction V. As  FIG. 4  shows, the cross-sectional shape of the cutting elements  23  is selected to be triangular, so that a high proportion of hard material is positioned in the vicinity of or near the cutting edge  23 . 2 . In this way, a long service life is possible in a manner optimized with regard to material. 
         [0043]    Once the cutting elements  23  have reached their wear limit, the cutting insert  20  can be replaced without problems. All that has to be done is for the fastening screws  16  to be loosened, and the cutting insert  20  to be replaced by an unworn cutting insert  20 . Under impermissible usage conditions, it can sometimes happen that a cutting element  23  of a cutting insert  20  will break prematurely. In that case, the cutting insert  20  can easily be replaced. This requires merely loosening the fastening screws  16 . 1  of all the cutting inserts  20 , pushing the cutting inserts  20  apart, and then removing the damaged cutting insert  20 . A new cutting insert  20  can be attached, the cutting inserts can be pushed against one another again, and the fastening screws  16  can be tightened. These maintenance jobs can be performed easily and without danger, because the cutting inserts  20  form compact structural units, which are only slight in weight on their own and are easy to handle.