Beater bar for an impact crusher, in particular a rotary impact crusher

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.

BACKGROUND OF THE INVENTION

1. Field of the Invention

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.

2. Discussion of Related Art

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.

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.

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

One object of this invention is to provide a rugged blow bar that is easy to service.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The fastening lug can be manufactured simply and dimensionally precisely if it has a square or rectangular geometry in cross-section.

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.

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.

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.

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.

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.

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.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a blow bar, which has a carrier10. The carrier10has a base part11, which forms a front face12pointing in the tool-advancing direction (V). The base part11is adjoined laterally by a lower part13, and the impact rocker13has an upper face oriented toward the front face12. Facing away from the impact rocker13, the base part11has a lug, into which a recess18in the form of a milled-out area is machined. The recess18forms a supporting surface18.2and a bearing surface18.1at an angle to it. The supporting surface18.2pointing in the tool-advancing direction (V) transitions to a diverting surface19. On the back, the carrier10has protrusions15, which are used for fixing a rotor of a rotary impact crusher. On both sides of the protrusions15, supporting surfaces14are provided. In the vicinity of or near the impact rocker13, the carrier10forms a seating surface17. This face is disposed at an angle to the supporting surface14on the back. By means of or with the supporting surface14and the seating surface17, the carrier10can be reliably supported on the rotor. As shown inFIG. 1, four cutting inserts20are built into the recess18, which are disposed side by side in the longitudinal direction of the carrier10.

FIG. 2shows the arrangement ofFIG. 1in perspective in a rear view. As shown in this view, three protrusions15which are separated from one another by grooves are integrally formed onto the base part11on the back. Beginning at the back side of the carrier10, fastening sockets16in the form of bores are made in the carrier10. These bores open in the bearing surface18.2of the recess18. Fastening screws16.1can be passed through the fastening socket16and screwed into the cutting inserts20, as will be explained hereinafter.

As shown inFIG. 3, the cutting insert20includes a cutting element holder21, on which cutting elements23and wear plates22are fastened. The cutting element holder21has a vertical contact surface21.8, which is adjoined by a bottom21.1via a chamfer21.10. In the assembled state, the bottom21.1is supported on the bearing surface18.1of the carrier10, and the contact surface21.8is supported on the supporting surface18.2. The chamfer21.10guarantees reliable contact with the supporting surface18.2and bearing surfaces18.1. At the front, the bottom21.1transitions to a diagonally extending transitional portion21.2. The transitional portion21.2is adjoined by a front face21.3, which is positioned at an angle greater than 90° relative to the bottom21.1extending 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 face21.3is an adjoining milled-out area21.5into which the wear plates22are inserted. The milled-out area21.5is dimensioned so that the surfaces of the wear plates22transition flush to the front face21.3. The milled-out area forms a contact surface21.4with which the wear plates22can be aligned. As a result, simpler manufacture is possible. The wear plates22are firmly soldered in the milled-out area21.5on the back by hard solder.

The milled-out area21.5is adjoined by a seating surface21.6. This seating surface21.6is inclined counter to the tool-advancing direction V and toward the back side of the cutting insert20. The cutting element23can be firmly soldered to the seating surface21.6with a flat supporting portion23.5. The cutting element23is dimensioned so that with a protrusion23.4on its underside, it covers the face end, oriented toward it, of the wear plate22, and an impact surface23.3on the front transitions flush to the front side of the wear plates22. This gapless, flush transition prevents crushed material from penetrating and exerting impermissible shear forces on the cutting elements23and the wear plates22. These shear forces would expose the hard-metal wear plates22and cutting elements23to the risk of breakage. The impact surface23.3extends in inclined fashion and points in the tool-advancing direction V. With a free surface23.1, the impact surface23.3forms an angle of less than 90°, and in the transition region between the free surface23.1and the impact surface23.3, a cutting edge23.2is formed. The free surface23.1in turn transitions flush to a diverting surface21.7of the cutting element holder21.

FIG. 4shows that the cutting elements23are provided laterally with side surfaces23.5that extend in the tool-advancing direction V. Via these side surfaces23.5, the cutting elements23can be lined up with one another in gapless, flush fashion. Per cutting element23, two wear plates22each are built in, and the two wear plates22have a total width that is equivalent to the width of the cutting element23.

As shown inFIG. 5, preferably eight cutting elements23are fastened to one cutting element holder21. Accordingly, sixteen wear plates22are used.

It shown inFIGS. 4 and 5that on the back side of the cutting element holder21, three fastening lugs21.9protrude past or beyond the contact surface21.8. The fastening lugs are embodied with a square cross section and are penetrated by a blind-bore-like threaded opening24, as shown particularly inFIG. 4. The threaded opening24terminates behind the wear plates22in the cutting element holder21. The threaded opening24has a center longitudinal axis M which can be disposed or positioned in alignment with the fastening socket16of the carrier10. With the cutting insert20, the carrier10here has three recesses, which have a cross-sectional shape corresponding to the fastening lugs21.9. The internal dimensions of these recesses are selected to be slightly larger than the external dimensions of the fastening lug21.9. In this way, play is created, which enables a limited adjustment of the cutting insert20relative to the carrier10, when the cutting insert20is in an unfixed preassembly position.

FIG. 4also shows that the diverting surface21.7transitions flush to the free surface23.1. Beginning at the cutting edge23.2, the free surface23.1is 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 edge23.2.

For assembling the cutting inserts20, they are inserted by their fastening lugs21.9into the corresponding recesses18in the carrier10. Next, from the back side of the carrier10, the fastening screws16.1are passed through the fastening sockets16and screwed into the threaded opening24in the cutting element holder21. At this time the fastening screws16.1have not yet been tightened, so that the cutting inserts20are in a preassembly position. Next, the cutting inserts20are pushed against one another in the longitudinal direction L, as shown inFIG. 5, of the cutting inserts20on the supporting surface18.2and the bearing surface18.1, so that they contact one another in gapless fashion. The displacement motion is enabled by the play between the fastening lugs21.9and the recesses in the carrier10. Once the cutting inserts20have been pushed against one another, the fastening screws16can be tightened with the prescribed torque, and the cutting inserts20are then securely fastened to the carrier10.

During operational use, wear to the cutting edge23.2of the cutting elements23occurs because of the contact with the rock materials that are to be crushed. In the process, the cutting elements23become worn in the vertical direction, such as transversely to the tool-advancing direction V. AsFIG. 4shows, the cross-sectional shape of the cutting elements23is selected to be triangular, so that a high proportion of hard material is positioned in the vicinity of or near the cutting edge23.2. In this way, a long service life is possible in a manner optimized with regard to material.

Once the cutting elements23have reached their wear limit, the cutting insert20can be replaced without problems. All that has to be done is for the fastening screws16to be loosened, and the cutting insert20to be replaced by an unworn cutting insert20. Under impermissible usage conditions, it can sometimes happen that a cutting element23of a cutting insert20will break prematurely. In that case, the cutting insert20can easily be replaced. This requires merely loosening the fastening screws16.1of all the cutting inserts20, pushing the cutting inserts20apart, and then removing the damaged cutting insert20. A new cutting insert20can be attached, the cutting inserts can be pushed against one another again, and the fastening screws16can be tightened. These maintenance jobs can be performed easily and without danger, because the cutting inserts20form compact structural units, which are only slight in weight on their own and are easy to handle.