Pick, In Particular A Round-Shank Pick

The invention relates to a pick, in particular to a round-shank pick for use on a cutting roller, said pick having a pick head and a pick shank for supporting the pick in a pick holder, wherein the pick head of the pick comprises at least one cutting region.

A pick of this type is disclosed in DE 37 01 905 C1. Said pick consists of a pick head and a pick shank which is integrally formed thereon in the form of a round shank. The pick head and pick shank are designed so as to be rotationally symmetrical about a center longitudinal axis of the pick. The transition of the pick head to the pick shank is realized as a collar which forms the largest external diameter of the pick head. The pick head tapers conically toward a pick tip. The pick tip is formed by a tungsten carbide insert. The pick is held by its pick shank in a corresponding receiving means of a pick holder by means of a clamping sleeve. In this case, the clamping sleeve engages in such a manner in a groove which runs around the pick shank that the pick is held in the axial direction, but is able to rotate about its center longitudinal axis. This provides the advantage of the pick wearing evenly on all sides during its use.

Such picks are used, for example, on rotating cutting rollers of so-called surface miners for removing rock and earth in large-scale open cast mining. In this case, the excavated material is crushed by the picks, which are fastened on the cutting roller, and is transported by means of the movement of the cutting roller to an ejector where it is then removed, for example by means of a conveyor system.

A disadvantage of the described picks is their limited transport capacity on account of their design, in particular for softer excavated materials, such as, for example, for oil sand.

It is, consequently, the object of the invention to create a pick of the type mentioned in the introduction with improved conveying function.

The object of the invention is achieved in that a planar and/or hollowed ejection region is arranged in a central region of the pick head connecting indirectly or directly to the cutting region. The earth or rather the rock is broken up and crushed by the cutting region. The planar ejection region collects the excavated material and transports it in the feed direction of the pick and of the cutting roller. As a result of the planar development of the ejection region, finely crushed, plastically deformable or sandy excavated material is also reliably collected and, following the rotation of the cutting roller, is transported in large quantities to an ejector.

A high cutting capacity with the pick, at the same time, having a long service life is achieved as a result of the cutting region comprising at least one cutting element which is produced from a hard material, in particular tungsten carbide, and is attached on an end of the pick remote from the pick shank on a front side of the pick head which is aligned in the direction of a feed device (V) and/or as a result of the ejection region comprising at least one plate-shaped hard material element, in particular produced from tungsten carbide, which connects indirectly or directly to the cutting element. The cutting element and the plate-shaped hard material element protect the region of the pick head arranged behind them from abrasive wear. In this case, a particularly high level of resistance to wear is achieved when the hard material element connects directly to the cutting element such that there is no gap between the elements which can be attacked by the excavated material.

The removal, in particular of viscous or sandy excavated material, can be improved as a result of a deflection region, which extends toward the front side of the pick, being arranged indirectly or directly on the ejection region of the pick head, and as a result of a shovel-shaped trough, which is aligned toward the front side of the pick, being formed by the cutting region, the ejection region and the deflection region. Plastically deformable excavated material in the cutting region, for example, is removed through the trough and formed in the shape of a ball or roller over the ejection region and the deflection region. The material formed in this manner is transported further through the ejection region and, in this case, is held by the deflection region. Sandy excavated material is held in the trough by the deflection region.

The abrasive wear of the pick head can be reduced further as a result of the pick head comprising a carrier portion which is arranged in the cutting region and the ejection region, and as a result of the carrier portion comprising lateral connection faces which are arranged on both sides of the carrier portion in the cutting region and/or the ejection region, the mutual distance between said lateral connection faces, proceeding from the front side toward a rear side of the pick, being reduced. The width of the carrier portion consequently tapers, proceeding from the front side of the pick, which is directly exposed to the excavated material, toward the rear side thereof. As a result of the undercut formed in such a manner, the lateral connection faces are only exposed to a reduced mechanical load by the excavated material. The heavily loaded front side can be protected, as depicted, by cutting elements and hard material elements such that long service lives can be achieved for the picks. A further advantage is produced as a result of a pick formed in this manner being able to be moved in an easier manner through the earth. The power to be applied for moving the cutting roller is consequently reduced, as a result of which energy is able to be saved.

Corresponding to a preferred development variant of the invention, it can be provided that the cutting element is formed from a fastening piece which is aligned toward the front side of the pick and from an attachment which is aligned from the fastening piece toward the rear side of the pick, that the cutting element forms a cutting edge on the outermost end of the pick head and that the cutting element, proceeding from the cutting edge, realizes a diverting face toward the fastening piece and a free face toward the attachment. The cutting edge which is heavily loaded mechanically and the regions which directly connect to the cutting edge and are also heavily loaded mechanically are consequently protected from increased wear by a hard material. This leads to a clear increase in the service life of the pick head.

Secure fastening of the cutting element on the carrier portion can be achieved as a result of the fastening piece realizing a contact face and the attachment realizing a support portion and as a result of the cutting element, by means of a substance-to-substance bond between the contact face and contact region and/or between the support portion and a support region of said carrier portion, being held on the carrier portion. The substance-to-substance bond can be produced, for example, by gluing or, in a preferred manner, by soldering. In this case, a particularly durable connection is produced when such a connection is produced both between the contact face and the contact region and between the support portion and the support region. The risk of breakage for the cutting element can be additionally reduced as a result of such a two-sided fastening.

The service life of the pick head can be lengthened as a result of the pick head being coated with an anti-wear coating, in particular with an armor welding, in the cutting region, in the ejection region and/or in the deflection region. As a result, for example in the cutting region, which is particularly mechanically loaded, the lateral connection faces as well as a connection face, which is arranged as an extension of the free face of the cutting element, can be provided with the anti-wear coating and consequently protected against abrasive wear. In a corresponding manner, the lateral connection faces in the ejection region of the pick head can also be protected with an anti-wear coating. As a result of said measures, the carrier portion behind the cutting element and behind a hard material element can be prevented from being washed out and, as a result, the cutting element or the hard material element from being detached from the carrier portion. The deflection region, which connects to the ejection region, can be provided with an anti-wear coating toward the front side of the pick head and can consequently be protected. As a result of said measure, the trough of the pick head, which is aligned toward the front side of the pick head and is directly exposed to the excavated material, can be completely protected from rapid abrasive wear. In an advantageous manner, in this case, the cutting region which is loaded the heaviest and the ejection region which is also heavily loaded are protected toward the front side by the cutting element and the hard material element and the less loaded deflection region is protected by the anti-wear coating. As a result, a comparably long service life can be achieved for all regions of the pick head such that the pick head is not destroyed prematurely by failure of a component.

In order to avoid the cutting element or the hard material element being destroyed during the coating process or the supporting faces, on which the cutting element or the hard material element are mounted, being deformed, it can be provided that the anti-wear coating is applied to the cutting element and/or to regions of the carrier portion carrying the hard material element at least at a spacing of a minimum distance. In particular, when applying the anti-wear coating as armor welding, very high temperatures are reached in the welding region. The minimum distance avoids the cutting element, the hard material element or the supporting faces thereof on the carrier portion being exposed to high temperatures and being destroyed or deformed as a result.

A high cutting capacity with at the same time fewer torsion forces transmitted into the pick head can be achieved as a result of the cutting edge of the cutting element being arranged in the direction longitudinally of a center longitudinal plane (M) of the pick, the surface normal of which points in the direction of the front side of the pick, in particular as a result of the cutting edge being arranged along the center longitudinal plane (M) of the pick.

Corresponding to a preferred realization of the invention, it can be provided that the cutting element comprises on the front side a diverting face which is formed in a belly-shaped manner, in particular convexly, and/or that the diverting face comprises an edge which is aligned toward the front side at a first exterior angle and/or that the cutting edge comprises a cutting tip at a second exterior angle and/or that the free face comprises an edge at a third exterior angle and/or that the exterior angles are arranged over a in the direction longitudinally of a second center longitudinal plane of the pick which extends from the front side to the rear side. As a result of the belly-shaped diverting face, the cutting element is reinforced in a region which is subject to particularly serious wear in such a manner that the service life of the cutting element is able to be significantly increased. The same also applies to a diverting face which comprises a forwardly pronounced edge along the center longitudinal plane. As a result of the belly-shaped form, the excavated material is transported in a reinforced manner to the ejection region. As a result of the edge, the movement of the excavated material additionally obtains a lateral component such that it is present in a more evenly distributed manner in the ejection region. As a result of the realization of a cutting tip, the pick penetrates in an easier manner into harder earth and rock. In this case, non-removed excavated material can be pressed to the side by a free face which is also provided with an outside edge. A cutting element with an edge which is arranged along the center longitudinal plane, which extends from the front to the rear side of the pick, shows better cutting and excavating results with harder material, whilst a convexly formed cutting element is better suited for soft and plastically deformable earth. Picks with cutting elements with an outside edge can consequently be used, for example, in winter when the earth is frozen, whilst picks with belly-shaped cutting edges are provided in the summer.

In contrast to a pick with a rotationally symmetrical, tapering pick head, the pick according to the invention comprises a defined front and rear side. So that the front side, provided with the cutting element, can remain aligned in the feed direction in operation, it can be provided that the pick shank is realized as a round shank and that the pick shank comprises at least one positive locking element which is suitable to interact with a positive locking counter element of the pick holder or that the pick holder has assignable thereto a blocking piece as a positive locking counter element which is securable on the pick holder and that the pick is securable in an anti-rotational manner on the positive locking counter element by way of the positive locking element. The pick is thus held in the pick holder in an anti-rotational manner in spite of its round pick shank. In an advantageous manner, the pick can be held in the same pick holders as known round-shank picks which have a symmetrical pick head and in operation are rotated about their center longitudinal axis. Consequently, a cutting roller can be provided with known rotating picks or with blocked picks according to the invention in dependence on the material to be removed.

In order to block the pick in its axial position and to protect the pick holder from increased wear, it can be provided that the pick head comprises a support body on the side of the pick shank and that the support body is closed off by means of a support face which protrudes radially above the pick shank. The support face thus lies on an end face of the pick holder which runs around a pick receiving means. As a result, a large-area supporting face is produced between the pick head and the pick holder such that large forces introduced in the axial direction onto the pick head can also be transmitted to the pick holder without deforming the supporting faces. As a result of the protrusion of the support body, the excavated material is steered past the pick holder such that the abrasive attack of the excavated material on the pick holder is able to be kept small.

The material flow of the excavated material is influenced in a decisive manner by the shaping of the trough of the pick head. The material crushed by the cutting element can be removed efficiently as a result of a deflection face, which runs from the ejection region to the front side of the pick head, being formed by means of the deflection region and as a result of the deflection face, proceeding from a middle region of the pick head toward the front side thereof, falling away in the direction of the pick shank. The support body which lies under the deflection face is covered and protected by the protection face. There is a high level of mechanical protection in this case in particular when the deflection face is provided with an anti-wear coating.

The invention is explained in more detail below by way of an exemplary embodiment shown in the drawings, in which:

FIG. 1 shows a side view of a pick for removing comparatively soft material,

FIG. 2 shows a side view of the upper end of a pick head of the pick shown in FIG. 1 with a cutting element,

FIG. 3 shows a perspective rear view of the pick from FIG. 1,

FIG. 4 shows a side view of a second pick for removing comparatively harder material,

FIG. 5 shows a perspective rear view of the second pick from FIG. 4,

FIG. 6 shows a further perspective rear view of the pick from FIG. 1,

FIG. 7 shows a section through a pick holder corresponding to a cutting surface shown in FIGS. 1 and 4 and

FIG. 8 shows a detail of the pick shown in FIGS. 1 and 4 in the region of a blocking piece.

FIG. 1 shows a side view of a pick 10 for removing comparatively soft material, in particular oil sand or other plastically deformable or sandy earth.

The pick 10 comprises a pick head 20 and a pick shank 40 which is integrally molded thereon, the pick shank 40 being present essentially in the form of a cylindrical round shank 42. The pick head 20 comprises a support body 27 which faces the pick shank 40 and merges into a carrier portion 23. The carrier portion 23 forms a shovel-shaped trough 20.6 which is aligned toward a front side 20.1 of the pick 10 and of the pick head 20. The pick head 20 is divided along the shovel-shaped trough 20.6 into three regions marked by double arrows, namely into a front cutting region 20.3, a center ejection region 20.4 and a rear deflection region 20.5. In the cutting region 20.3, two cutting elements 30, which are arranged side by side, are fastened on the carrier portion 23 toward the front side 20.1 of the pick head 20, as can be seen more clearly in FIG. 3. In the ejection region 20.4, two plate-shaped hard material elements 28, which are arranged side by side, cover the carrier portion 23 which is located behind them. A deflection face 24.5, which is provided with an anti-wear coating 29 and extends as a result of a corresponding, lightly curved shape from the plane of the ejection region 20.4 formed by the hard material elements 28 to the front side 20.1 of the pick head 20, is arranged in the deflection region 20.5. The deflection face 24.5, in this case, is aligned in such a manner that it falls away from the transition to the ejection region 20.4 toward the front closure of the pick head 20.

In the rear-sided connection to the cutting elements 30 and the hard material elements 28, the carrier portion 23 realizes upper and lower lateral connection faces 25.1, 25.2. As can be seen in FIG. 1 and FIG. 3, the lateral connection faces 25.1, 25.2 are provided with an anti-wear coating 29. The lateral connection faces 25.1, 25.2 connect laterally to the cutting elements 30 and hard material elements 28 in their front-sided regions. The mutual distance between the lateral connection faces 25.1, 25.2, which are located oppositely on the two sides of the pick head 30, reduces toward a rear side 20.2 of the pick 10 and of the pick head 20.

As shown in FIG. 1 and in an enlarged manner in FIG. 2, the cutting element 30 is formed in a substantially L-shaped manner from a fastening piece 36 and an attachment 32, which is molded thereon at an angle to the rear side 20.2 of the pick head 20. Toward the front side 20.1, the fastening piece 36 can comprise a diverting face 37 which is formed in a belly-shaped manner and merges into a cutting edge 31 at the outermost end of the cutting element 30 and consequently of the pick head 20. Proceeding from the cutting edge 31, a downwardly sloping free face 33, which is aligned in an opposite manner to a feed direction V of the pick 10, is formed by the attachment 32. Located opposite the diverting face 37, the fastening piece 36 comprises a contact face 35 which is at an angle to a support portion 34 which is arranged opposite the free face 33. The contact face 35 and the support portion 34 are placed onto a contact region 24.2 and a support region 24.1 of the carrier portion 23 and are connected thereto by means of a substance-to-substance bond produced, for example, by soldering. As an alternative to this, the substance-to-substance bond can also be produced by gluing. As an extension to the free face 33, the carrier portion 23 comprises a connection face 26.1 which is also provided with an anti-wear coating 29 and merges into a rounding region 26.2 of the carrier portion 23. The inclined alignment of the connection face 26.1 merges via the rounding region 26.2 into the alignment of the outside face of the support body 27, which extends along the direction of a center longitudinal plane M.

The cube-shaped hard material elements 28 are fastened on the front side 20.1 of the pick head 20 directly connected to the cutting elements 30. To this end, the hard material elements 28 are connected by way of their rear side to a fastening plane 24.4 of the carrier portion 23 in a substance-to-substance bonding manner as a result of, in the present exemplary embodiment, soldering, as an alternative to this as a result of gluing. For the precise positioning of the hard material element 28, a step-shaped positioning edge 24.3, against which the hard material element 28 abuts by way of its upper end face, is provided between the contact region 24.2 and the fastening plane 24.4.

The anti-wear coating 29 of the lateral connection faces 25.1, 25.2 of the connection face 26.1 and of the deflection face 24.5 is spaced from the cutting element 30 or rather from the hard material element 28 by a minimum distance.

The closure of the pick head 20, located opposite the cutting element 30, is formed by the cylindrical support body 27, which merges integrally into the pick shank 40. In this case, a conical centering portion 41, which runs around the cylindrical round shank 42, is provided in the transition from an end-side support face 27.1 of the support body 27, which protrudes radially beyond the pick shank 40, to the round shank 42. A conical tapering region 43, on which a positive locking element is integrally molded in the form of a blocking pin 44, connects to the round shank 42. The blocking pin 44 comprises pin faces 44.1 on the two lateral faces and on the rear side and a pin rounding 44.2 to the front side 20.1. The pick shank 40 is closed off at the end by a disk-shaped end piece 46 which is separated from the blocking pin 44 by a groove 45.

As shown further by FIG. 1, the pick 10 is held in a pick holder 50 over its pick shank 40. The pick holder 50 is shown in a sectional representation for the purposes of better presentation.

The pick holder 50 comprises a holding region 54 toward the pick head 20 and a base part 56 located opposite. It has a cylindrical basic form which is tapered as a result of an inclination 53 in a region which faces the pick head 20. The inclination 53 merges via a rounded edge into an end face 51, which is aligned transversely with respect to the center longitudinal axis of the pick 10 and against which the support face 27.1 of the pick head 20 abuts. Toward the pick shank 40, the end face 51 comprises a centering receiving means 52 in the form of a bevel which is adapted to the centering portion 41 of the pick 10. The centering portion 41 forms the closure of a pick receiving means 55 which is arranged in the holding region 54 of the pick holder 50. The pick receiving means 55 is realized as a cylindrical bore following the contour of the round shank 42 of the pick shank 40.

As can be seen from FIG. 1 and from the perspective rear view from FIG. 3, the base part 56 of the pick holder 50, by means of a front wall 56.5 which is aligned toward the front side 20.1 and a rear-sided mounting opening 56.3, forms a part-surrounded cavity 57, which is open through the mounting opening 56.3 and toward the end side of the pick holder 50. The mounting opening 56.3, in this case, is delimited by closure faces 56.4 of the approximately semicircular front wall 56.5, the closure faces 56.4, proceeding from the holding region 54 of the pick holder 50, being arranged extending toward the lower end of the base part 56 at an angle toward the front side 20.1 of the pick holder 50.

The cavity 57 itself is delimited toward the front side 20.1 by the front wall 56.5 by way of its approximately semicircular front wall face 56.1 which merges laterally into two side wall faces 56.2, which open slightly toward the mounting opening 56.3 and extend in a straight line, as is shown more clearly in a sectional representation in FIG. 7 which extends along the cutting line marked by reference VII.

As is further shown in FIG. 1, the blocking pin 44 of the pick shank 40 is secured in a blocking piece 60 which is shown in a sectional representation. The blocking piece 60 is held by a clamping element 70, which engages in the groove 45 of the pick shank 40, in the axial direction thereof. The blocking piece 60 forms a positive locking connection in relation to both the pick holder 50 and in relation to the blocking pin 44, said positive locking connection preventing a rotation of the pick 10 about its center longitudinal axis. The blocking pin 44 is held for this purpose in a breakthrough 64 of the blocking piece 60.

The pick holder 50 is not shown with its front side 20.1 welded on a cutting roller. For mounting onto the pick holder 50, the pick 10 is inserted with its pick shank 40 into the pick receiving means 55 thereof, the blocking piece 60 is fitted onto the blocking pin 44 and the clamping element 70 is clamped into the groove 45. The alignment of the blocking piece 10 is predefined by its outside contour and the contour of the cavity 57. The alignment of the pick 10 is also determined by the shape of the blocking pin 44 and of the breakthrough 64 of the blocking piece 60 such that its front side 20.1 points in the feed direction V of the cutting roller and consequently of the pick 10. In the axial direction, the pick 10 is determined by the contact of the pick head 20 with its support face 27.1 on the end face 51 of the pick holder 50 as well as by the clamping element 70 which engages in the groove 45. The pick 10, which is realized as a round-shank pick, is consequently held in a non-rotatable manner in the pick holder 50.

In operation, the pick 10 is driven through the earth to be removed in the feed direction V by the rotation of the cutting roller. In this case, first of all the front cutting edge 31 engages in the earth and crushes it. As a result of the cutting edge 31, which is wide compared to a pick tip of a known round-shank pick, the earth is removed and collected along a comparatively wide line. The excavated material, which is removed in this manner, is directed into the ejection region 20.4 of the pick head 20 as a result of the convex design of the deflecting face 37 of the cutting element 30. There, the excavated material is collected by the hard material elements 28 and entrained in a manner corresponding to the rotation of the cutting roller. In particular, where the excavated material is not consistent, such as, for example, rock or non-adherent sand, the deflection face 24.5 prevents the excavated material from flowing out of the trough 20.6. In the case of plastically deformable excavated material, it is guided as a result of the shovel shape of the trough 20.6 from the cutting region 20.3 via the ejection region 20.4 to the deflection region 20.5 and, at the same time, is formed into ball-like or roller-like clumps. The material, which is formed in this manner, is transported in the trough 20.6 for example to an ejector, from where it is then removed, for example by a conveyor system (not shown).

The top surface of the pick head 10, which forms the trough 20.6 in the cutting region 20.3 and in the ejection region 20.4 and is formed, in the present exemplary embodiment, by the cutting elements 30 and the hard material elements 28, extends substantially along the center longitudinal plane M of the pick 10. In this case, the surface normal of the center longitudinal plane M points in the direction of the front side 20.1 of the pick 10. The pick head 20 comprises its largest diameter in the region of the center longitudinal plane M. Consequently, the cutting region 20.3 and the ejection region 20.4 can be realized in a very wide manner transversely with respect to the feed direction V, as a result of which a high conveying capacity is produced for the excavated material. The pick 10 is consequently particularly suitable for excavating comparatively soft material, for example oil sand.

The cutting region 20.3 is under the greatest mechanical load when the pick 10 is operating. Consequently, in said region the pick 10 is protected toward its front side 20.1 by the fastening piece 36 with the diverting face 37 of the cutting element 30 which is produced from a hard material, in the present case from tungsten carbide. As a result of the belly-shaped design of the fastening piece 36, the greatest material strength of the cutting element 30 lies in the region of the greatest abrasion, this then being reduced as the distance to the cutting edge 30 increases and consequently the mechanical load diminishes. As a result of said optimized use of material, the manufacturing costs of the cutting element 30, which are essentially influenced by the cost of the materials, can be reduced. The forces transmitted into the cutting elements 30 and consequently the breaking risk thereof are able to be reduced as a result of using two adjacent cutting elements 30 compared to one wider, single cutting element 30.

The attachment of the cutting element 30 can be guided past the remaining earth following the cutting edge 31 via the free face 33 which is aligned in the feed direction V. The free face 33 merges without a large step into the identically aligned connection face 26.1 such that, here too, no attack points are produced for the excavated material sliding past. The cutting element 30 is connected fixedly to the carrier portion 23 as a result of its solder connection to the contact face 35 and the support portion 34, the force being introduced onto the cutting element 30 substantially in a direction opposite to the feed direction V and consequently acting as a pressing force onto the boundary face between the cutting element 30 and the carrier portion 23. High tensile forces which act on the boundary face can be avoided in this way such that the cutting element 30 is held reliably on the carrier portion 23. The connection face 26.1 as well as the upper lateral connection faces 25.1, which connect to the cutting element 30 on the oppositely situated sides of the pick head 10, are provided with the anti-wear coating 29 which is realized as armor welding. Consequently, the cutting region 20.3 is fully wear-protected except for a minimum distance provided between the anti-wear coating 29 and the cutting element 30. The anti-wear coating 29 prevents, in particular, the region of the carrier portion 23 connecting to the cutting elements 30 from being washed out and, as a result, the cutting elements 30 coming loose from the carrier portion 23.

The ejection region 20.4 is protected by the hard material elements 28 toward the front side 20.1. As the ejection region 20.4 is under less of a load than the cutting region 20.3, the material strength of the hard material elements 28 is reduced compared to the material strength of the cutting elements 30. The hard material elements 28 are connected to the carrier portion 23 as a result of a substance-to-substance connection which is produced by soldering. The lower lateral connection faces 25.2, which connect to the hard material elements 28 and the deflection face 24.5, are also protected from increased abrasion with armor welding as an anti-wear coating 29 such that the region behind the hard material elements 28 is not washed out either. On the rear side, the carrier portion 23 is set back in the ejection region 20.4 and in the deflection region 20.5 from the remaining excavated material by the rounding region 26.2 such that, here, there is only a comparatively small abrasive load on the pick head 20 when the pick 10 slides past the earth. In order to keep the manufacturing costs low, no anti-wear coating 29 is provided in said region.

As the mutual distance between the oppositely situated upper lateral connection faces 25.1 and the oppositely situated lower lateral connection faces 25.2, proceeding from the cutting elements 30 or rather from the hard material elements 28, is reduced toward the rear side 20.2 of the pick head 20, an undercut is formed. The lateral connection faces 25.1, 25.2 consequently do not form an attack point for the excavated material. As a result, on the one hand the wear on the lateral connection faces 25.1, 25.2 is reduced, on the other hand the pick 10 can be pulled through the earth to be excavated in an easier manner. As a result, the output necessary to drive the cutting roller is reduced, as a result of which energy is saved.

The deflection region 20.5 is subjected to the least abrasion compared to the cutting region 20.3 and the ejection region 20.4. Consequently, the anti-wear coating applied to the deflection face 24.5 provides sufficient protection of the deflection region 20.5. It is thus possible to dispense with expensive hard material elements in the deflection region 20.5. The anti-wear coating is consequently adapted in such a manner to the different mechanical loads of the cutting region 20.3, of the ejection region 20.4 and of the deflection region 20.5 that substantially identical service lives are produced for all the regions. This avoids the pick 10 failing prematurely on account of design-related premature wear in one region. At the same time, the use of the material, in particular for the cost-intensive hard materials and anti-wear coatings 29, is optimized.

The anti-wear coating 29 is applied to the cutting elements 30 and the hard material elements 28 only up to a minimum distance. This avoids the cutting elements 30 or the hard material elements 28 being damaged or destroyed by the high temperatures which occur with the coating. In addition, thermally-related deformation of the contact regions for the cutting elements 30 and the hard material elements 28 is avoided.

The substantially cylindrically realized support body 27 covers the upper region of the pick holder 50 and consequently protects it from premature wear. Consequently, this results in a service life for the pick holder 50 being significantly longer than that of the easily exchangeable pick 10 itself. A large-area supporting face of the pick head 20 is formed on the end face 51 of the pick holder 50 by the support face 27.1 of the support body 27 which is arranged about the pick shank 40 such that deformation as a result of forces introduced via the pick head 20 are able to be avoided in said region.

The pick receiving means 55 comprises a diameter which is larger by a predefined clearance compared to the round shank 42 of the pick 10, whereby the pick shank 40 is able to be introduced easily into the pick receiving means 55 during mounting and driven out again during removal. A precise alignment of the pick 10 and of the pick shank 40 in relation to the pick receiving means 55 is obtained as a result of the centering portion 41 interacting with the centering support 52.

In the holding region 54, the pick holder 50 is realized in a thick-walled manner about the pick receiving means 55, which is realized as a central bore, in order to be able to absorb, in a reliable manner, the cross forces which are transmitted by the pick holder 40. To this end, the diameter of the pick holder 50, proceeding from the end face 51 which faces the pick head 10, is widened by the inclination 53. Excavated material sliding past is directed past the pick holder 50 by the inclination 53 without any protruding edges such that the abrasion forces are able to be kept as low as possible in said widened region of the pick holder 50.

By way of its front wall 56.5, the base part 56 of the pick holder 50 surrounds the formed cavity 57 toward the front side 20.1. In this case, the outside contour of the front wall 56.5 is adapted to the outside contour of the connecting holding region 54 such that the pick holder 50 is able to be placed into a corresponding receiving means on the cutting roller and welded there.

During mounting, the blocking piece 60 can be slid through the mounting opening 56.3 onto the blocking pin 44 and fixed, together with the pick 10, by way of the clamping elements 70. Rotation of the pick 10 about its center longitudinal axis is inhibited as a result of a positive locking connection between the blocking piece 60 and the blocking pin 44. In a corresponding manner, rotation of the blocking piece 60 about the center longitudinal axis of the pick 10 is blocked by a second positive locking connection between the blocking piece 60 and the base part 56. In this case, the positive locking connections between the blocking piece 60 and the blocking pin 44 of the pick 10 as well as between the blocking piece 60 and the base part 56 are realized in such a manner that the blocking piece 60 can only be introduced into the cavity 57 in a radial alignment and the pick 10 can only be introduced into the breakthrough 64 of the blocking piece 60 in one direction of rotation. The shovel-shaped trough 20.6 of the pick head 10 is consequently always aligned toward the front side 20.1 and consequently toward the feed direction V.

To remove the pick 10, the clamping element 70 is pulled out of the groove 45 and the blocking piece 60 removed. The pick 10 can now be driven out, where applicable with the aid of a driving-out tool, from the side of the opening in the base part 56 which is situated opposite the holding region 54.

FIG. 4 shows a side view of a second pick 11 for removing comparatively harder material. Identical components, in this case, are designated identically in a manner corresponding to FIGS. 1 to 3.

In contrast to the pick 10 shown in FIGS. 1 to 3, the second pick 11 shown in FIG. 4 comprises simply a cutting region 20.3 and an ejection region 20.4. In the cutting region 20.3, the carrier portion 23 is covered toward the front side 20.1 of the pick head 20 by one single, substantially L-shaped cutting element 30. As an extension of the fastening piece 36 of the cutting element 30, a cube-shaped hard material element 28 is mounted on the front side 20.1 of the carrier portion 23 in the connecting ejection region 20.4. Two or more hard material elements 28, which are arranged side by side, can also be provided as an alternative to this.

As shown in FIG. 4 and in particular in a perspective rear view of the second pick 11 in FIG. 5, the diverting face 37 is realized in a roof-shaped manner, an edge of the diverting face 37, which is formed in a manner corresponding to a roof ridge, being aligned along a center longitudinal plane of the second pick 11 which extends from the front side 20.1 to the rear side 20.2. The cutting element 30 is mounted on the carrier portion 23 aligned in such a manner at an angle to the center longitudinal plane of the second pick 11 that the edge points approximately in the feed direction V of the second pick 11. The free face 33, which is formed by the attachment 32, is also realized in a roof-shaped manner, the face plane being aligned here along the feed direction V. An edge of the free face 33, which extends in a manner corresponding to a roof ridge, is also arranged along the center longitudinal plane of the second pick 11 which extends from the front side 20.1 to the rear side 20.2. In the transition region from the diverting face 37 to the free face 33, the cutting edge 31 is formed as a result with a cutting tip 38 which lies on the center longitudinal plane. In an alternative embodiment, the cutting region 20.3 can also bear two cutting elements 30 which are designed in a mirror-symmetrical manner and abut against one another along the described edges which extend on the center longitudinal plane.

Following the free face 33 of the cutting element 30, the carrier portion 23 comprises a flat connection face 26.1 which is aligned in the same direction as the attachment 32 of the cutting element 30. The connection face 26.1 is provided in part with an anti-wear coating 29. At the rear end of the pick head 20, the connection face 26.1 bends into a rear-sided surface area of the pick head 20 which extends equidistantly to the center longitudinal axis of the second pick 11. Said rear-sided surface area merges seamlessly into the cylindrical region of the support body 27.

The hard material element 28 is mounted in a manner slightly inclined toward to the front side 20.1 of the ejection region 20.4 in relation to the center longitudinal plane M. The positioning edge 24.3 for positioning the hard material element 28 is formed by a step on the lower end of the ejection region 28, from which the pick head 20 assumes a cylindrical outside contour toward the front side 20.1. The hard material element 28 is placed onto the position edge 24.3 by way of an end face.

The pick head 20 of the second pick 11 does not realize a trough 20.6, as is the case with the pick 10 shown in FIGS. 1 to 3. The front surface area of the carrier portion 23 of the second pick 11, which is formed by the diverting face 37 of the cutting element 30 and the hard material element 28, is guided, proceeding from the cutting edge 31 arranged in the region of the center longitudinal plane M, in the direction of the front side 20.1 of the pick head 20. Consequently, the carrier portion 23 of the second pick 11 comprises a significantly greater material strength than the carrier portion 23 of the first pick 10 shown in FIGS. 1 to 3. The support body 27, the pick shank 40, the blocking piece 70, the clamping element 70 and the pick holder 50 are identically designed with identical functionality for both picks 10, 11.

The second pick 11 is particularly suited for the removal of hard, non-plastically deformable or non-sandy material. In addition, the second pick 11 can be used, in a preferred manner, in winter when the earth is frozen, for example in the case of frozen oil sand, whilst the pick 10 shown in FIGS. 1 to 3 is used when the ground has thawed.

The second pick 11 is also able to remove rock or frozen material as a result of the realized cutting tip 38. As a result of the reinforced carrier region 23, higher forces can be transmitted to the excavated material without the pick head 20 being damaged such that even hard material is able to be removed. As a result of the roof-shaped diverting face 37 of the cutting element 30, the solid excavated material is distributed laterally and then collected and removed by the hard material element 28 in the ejection region 20.4. The second pick 11 consequently provides a high cutting capacity and a high transport capacity for hard, brittle material.

FIG. 6 shows a further perspective rear view of the pick 10 from FIG. 1. The representation enables the view through the mounting opening 56.3 into the cavity 57 of the pick 10.

As shown in FIG. 6, the blocking piece 60 is placed onto the pick shank 40, only the end piece 46 of which can be seen, and is held by the clamping element 70 which is inserted into the groove 45 of the pick shank 40.

The blocking piece 60 shows an approximately U-shaped outside contour, by way of which it abuts against the correspondingly formed front wall 56.5 with its front wall face 56.1 and its side wall faces 56.2. As a result of said U-shaped form and the abutment against the side wall faces 56.2, the blocking piece 60 is blocked against rotation about the center longitudinal axis of the pick 10. The blocking piece 60 comprises a basic body 61, on which a web 63 is integrally molded. The web 63 surrounds a clamping receiving means 62 except for a region which is aligned in the direction of the mounting opening 56.3 of the pick holder 60. The clamping element 70 is arranged in the clamping receiving means 62 and clamped at the groove 45.

The clamping element 70 is realized in a plate-like manner with a rectangular basic form. A clamping region 73, which is comprised by two clamping jaws 74 and in which the pick shank 40 with its groove 45 is clamped, is provided proceeding from a front end face. A widening clamping slot 72, which ends at a bracket 71 which connects the clamping jaws 74, is provided centrally of the clamping element 70 proceeding from the clamping region 73. The clamping element 70 is preferably produced from a resilient material, in particular from a spring steel.

For mounting, the pick 10 is introduced with its pick shank 40 into the pick receiving means 55 of the pick holder 50. The blocking piece 60 is then slid through the mounting opening 56.3 onto the pick shank 40 and fixed with the clamping element 70. To this end, the clamping element 70 is pressed with its clamping region 73 onto the groove 45, the two clamping jaws 74 being pressed apart along the clamping slot 72 in order then to be placed fixedly in the groove 45 about the pick shank 40.

FIG. 7 shows a section through the pick holder 50 corresponding to a cutting face VII shown in FIGS. 1 and 4.

The semicircular front wall face 56.1 with the side wall faces 56.2, which connect thereto on both sides and extend in a straight line, is formed by the front wall 56.5 of the base part 56. The outside contour of the approximately U-shaped blocking piece 60 is adapted to the development of the front wall face 56.1 and of the side wall faces 56.2 such that it abuts against the front wall face 56.1 by way of a rounding 65.2, which is aligned toward the front side 20.1, and against the two side wall faces 56.2 of the front wall 56.5 by way of two blocking faces 65.1 which connect laterally to the rounding 65.2.

The contour of the breakthrough 64 of the blocking piece 60 is adapted to the outside contour of the blocking pin 44. To this end, the breakthrough 64 comprises, in each case to the rear side 20.2 and laterally, a breakthrough face 64.1 which, in each case, abuts against a pin face 44.1 of the blocking pin 44. Toward the front side 20.1, the breakthrough 64 comprises a convex breakthrough rounding 64.2 which abuts against a pin rounding 44.2 of the blocking pin 44.

As a result of the stepped cutting sequence shown in FIGS. 1 and 4, the end region of the clamping receiving means 62 can be seen with the bracket 71 of the clamping element 70 toward the mounting opening 56.3.

The alignment of the blocking piece 60 is fixedly predefined as a result of adapting the outside contour of the blocking piece 60 to the development of the front wall face 56.1 and of the side wall faces 56.2. In this case, a rotation of the blocking piece 60 about the center longitudinal axis of the pick 10, 11 is blocked by the blocking faces 65.1 which abut against the side wall faces 56.2.

The blocking pin 44 of the pick shank 40 can also only be introduced in one alignment into the breakthrough 64 of the blocking piece 60 on account of the pin rounding 44.2 and of breakthrough rounding 64.2 which corresponds thereto. The alignment of the pick 10, 11 and consequently of the pick head 20 is determined thereby. A rotation of the pick 10, 11 about its pick longitudinal axis is blocked by the pin faces 44.1 which abut against the breakthrough faces 64.1.

FIG. 8 shows a detail of the picks 10, 11 shown in FIGS. 1 and 4 in the region of the blocking piece 60. The blocking piece 60 is formed from the basic body 61, which includes the blocking pin 44 and realizes a stop face 61.1 in the direction toward the holding region 54 of the pick holder 50. The stop face 61.1 is arranged at a small distance in relation to a corresponding counter face 54.1 of the holding region 54, which is arranged radially about the pick receiving means 55. A guide web 66, the inside contour of which follows the blocking pin 44 and the outside contour of which follows the pick receiving means 55 of the pick holder 50, is integrally molded on the basic body 61 directly about the breakthrough 64. The guide web 66 is introduced into the end region of the pick receiving means 55, as a result of which the blocking piece 60 is radially secured. In order to avoid tilting during the mounting procedure, the guide web 66 comprises a bevel 66.1 all around. The blocking pin 44 is introduced into the breakthrough 64 of the blocking piece 60, by way of which the blocking pin realizes a positive locking connection which prevents the pick 10, 11 from rotating.

Toward the outer periphery, the basic body 61 comprises a circumferential beveling 61.2 which lies toward the front wall 56.5 in relation to a projection 56.6 of the base part 56 of the pick holder 50.

The web 63 is integrally molded on the basic body 61 on the side of the blocking piece 60 located opposite the holding region 54. The web 63 surrounds the clamping receiving means 62 except for a region which is aligned in the direction of the mounting opening 56.3 of the pick holder 60. The clamping element 70 is arranged in the clamping receiving means 62 and is clamped at the groove 45 which is realized between the blocking pin 44 and the end piece 46.

The blocking piece 60 consequently blocks a rotational movement of the pick 10, 11 and, interacting with the clamping element 70, a movement of the pick 10, 11 in the axial direction, except for a small clearance. The small clearance is produced from the small distance between the stop face 81.1 and the counter face 54.1. The clearance facilitates the mounting or rather the removal of the pick 10, 11 and compensates for tolerances. As a result of the stop face 61.1, tensile forces, which act axially on the pick 10, 11, are able to be transmitted to the pick holder 50 by means of the counter face 54.1. The clamping element 70 enables quick mounting and removal of the pick 10, 11. As the clamping element 70 is received in the clamping receiving means 62 of the blocking piece 60, it is protected from damage by penetrating excavated material to the greatest possible extent.

The pick holder 50 is able to receive both picks 10, 11 that are blocked from rotating and also such round-shank picks where rotation is desired. In this case, in the event of the latter, for example the blocking pin 44, the blocking piece 60 and the clamping element 70 are omitted, the known holding elements for blocking a movement of the round-shank pick in the axial direction having to be provided in their place. The cutting roller can thus be provided with different picks 10, 11 depending on the area of application.

Pick, In Particular A Round-Shank Pick

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