US3784258A - Guide system for mine-planer blades - Google Patents
Guide system for mine-planer blades Download PDFInfo
- Publication number
- US3784258A US3784258A US00223661A US3784258DA US3784258A US 3784258 A US3784258 A US 3784258A US 00223661 A US00223661 A US 00223661A US 3784258D A US3784258D A US 3784258DA US 3784258 A US3784258 A US 3784258A
- Authority
- US
- United States
- Prior art keywords
- segments
- rail
- planer
- assembly
- assembly defined
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000033001 locomotion Effects 0.000 claims abstract description 14
- 238000000429 assembly Methods 0.000 claims description 13
- 230000000712 assembly Effects 0.000 claims description 13
- 238000006073 displacement reaction Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 230000006872 improvement Effects 0.000 claims description 6
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- 238000005755 formation reaction Methods 0.000 claims description 4
- 239000003245 coal Substances 0.000 abstract description 15
- 238000009412 basement excavation Methods 0.000 abstract description 4
- 125000006850 spacer group Chemical group 0.000 description 6
- 229910052500 inorganic mineral Inorganic materials 0.000 description 5
- 239000011707 mineral Substances 0.000 description 5
- 210000003128 head Anatomy 0.000 description 4
- 230000010006 flight Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000000969 carrier Substances 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000004308 accommodation Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 210000000887 face Anatomy 0.000 description 1
- 230000003116 impacting effect Effects 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 230000000135 prohibitive effect Effects 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C35/00—Details of, or accessories for, machines for slitting or completely freeing the mineral from the seam, not provided for in groups E21C25/00 - E21C33/00, E21C37/00 or E21C39/00
- E21C35/08—Guiding the machine
- E21C35/12—Guiding the machine along a conveyor for the cut material
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F13/00—Transport specially adapted to underground conditions
- E21F13/06—Transport of mined material at or adjacent to the working face
- E21F13/066—Scraper chain conveyors
Definitions
- ABSTRACT A mine excavator such as a coal planer comprising a flight-type conveyor along the periphery of the conveyer trough or rail of which planer blades are provided to remove coal from the walls and floor of the excavation and direct the mass onto the conveyer.
- the guiding system for the planer blades comprises articulated guide segments mounted along the rails at the sides of the conveyer trough, limitedly movable in the vertical plane and grouped to include a pair of end segments separated by a central segment whose length is twice that of the end segments.
- the segments are hinged for relative angular movement about horizontal axes close to the floor-engaging (stress or impact) side of the assembly while successive pairs of central segments are interconnectedby high-force constant flexing rods traversing the intervening end segments of two successive sets.
- the segments are held in a channel of the conveyer pan with limited freedom of up and down movement and are enabled to cam in a plane parallel to the rails.
- Our present invention relates to coal planers and, more particularly, to a system for guiding the planar blades along the guide channels or rails'of a flight conveyor or similar appliance for removing excavated material, especially in single-chain flight conveyors.
- a planer for use in mine and other excavators generally comprises a conveying unit adapted to carry the excavated mineral matter and detritus away from the excavation site to a remote processing location, either directly or through the intermediary of other conveying means such as trucks, rail carriers, belts, buckets and the like.
- the planer is provided with planer blades along the edge of its conveyer which chisel, scrape or otherwise penetrate the wall and floor surfaces as the planer is advanced to dislodge chunks of coal, with or without non debris and detritus which is scooped up by the planer blades or by additional blades suitably provided and deposited upon the conveyer.
- the conveyer generally is of the flight type, i.e., comprises an elongated pan, tray or trough, reinforced at the edges by rails along which the planer blades are guided.
- a singlechain flight conveyer whereby the flights of the conveyer are interconnected by a single chain generally passing through the middle of the flights.
- the conveyer trough may have a generally flat floor along which the mineral matter is scraped by the flights.
- planer blades i.e., members whose crosssection is generally complementary to that of the rail and which is mounted thereon and carry the slidable planer blades which are of a length equal approximately to the length of the stroke of the reciprocating planer or a substantial portion of the length of the transport path along the trough.
- difficulties have been encountered. This is particularly the case when the conveyer is exposed to stress or impact in following the contours of the ground surface. Under these circumstances, the existing arrangements are ineffective because of the excessive length of the planer-blade supports or guides.
- the introduction of bent or curved paths for the planer blades has led to damage of conveyer troughs, excessive wear of the rails and the supports, and even to the generation of prohibitive noise volumes. Considerable stress is applied in the scraper itself and significant wear develops at any point of path flexion or deviation from the linear.
- Another object of the invention is to provide an improved blade-guide system for a single-chain flight conveyer coal scraper.
- Yet another object of our invention is the provision of improved means for mounting and guiding scraper blades for apparatus of the class described.
- planer-blade guide as a plurality of hingedly interconnected segments, coupled together so as to be biased resiliently into mutual alignment by a coupling rod common to at least two of the three segments forming each blade carrier assembly.
- the articulations between adjoining segments preferably allow relative angular displacement about axes parallel to the surface engaged by the blades or the blade carrier segments, e.g. parallel to the horizontal when the articulations are to enable the blades to ride over changing terrain.
- the guide means for the blades is so constructed and arranged as to allow relative movement of the trough and the blade carrier in a direction perpendicular to the aforementioned axes, i.e., in the vertical direction in the case described.
- each blade-guide assembly comprises three blade-guide segments including a pair of relatively short outer segments (end segments), and an intermediate relatively long segment (central segment) whose length is approximately twice that of each of the outer or end segments.
- Each of the latter segments thus has a length which is approximately half that of the central segment.
- the centering and alignment member may be a rod or bar traversing at least two segments and preferably anchored by ball joints in a pair of central segments of two adjoining assemblies while traversing the end segments between the central segments with a minimum of contact. The rods thus interconnect the adjacent assemblies.
- each of the blade-support assemblies are hinged or articulated to the central segment for relative rotation about axes orthogonal or perpendicular to the longitudinal direction of the guide rails and define, together with the central segments, an assembly length equal to the stroke of the planer blades.
- the end segments are thus enabled to pivot, relative to the central segment, through several degrees and the array of blades can, together with the blade guides be bent through relatively large angles distributcd over the several assemblies, thereby enabling the blade arrays to adjust to the ground contours more readily than has hitherto been the case.
- the end segments of course, not only are able to pivot with respect to one another (e.g.
- the end segments of adjoining assemblies can be tilted with respect to one another) so that the tilt of any one segment within the guide channel may be reduced, e.g. dimensioned to a half or a third of the usual canting motion for a given change in contour.
- the central segment of each assembly is provided at its ex tremities, close to the impact-receiving (ground) surface with hinge lugs which project longitudinally at either end and are received between bifurcated lugs or forks of the end segments.
- the latter may be received within recesses of the central segment and the single lugs of the latter may be received within a recess of the central segment to create a compact assembly with minimal spacing between the confronting faces of end and central segments.
- respective recesses in the central segment and corresponding protuberances of the end segments such that the protuberances extend into the recesses and define therein the articulation play establishing the maximum relative angle of tilt.
- the central and end segments can be provided with centering or aligning pins which also establish the angular play and enable the segments to be aligned for mounting.
- the central and end segments may be provided with abutment projections which can extend into a laterally open channel formed in the rail of the conveyor trough and which are dimensioned to allow the limited angular play therein mentioned earlier.
- the abutment projections also have the function of distributing the bending action more uniformly over the length of the tie rod interconnecting the assembly and preferably are formed with screw or bolt arrangements enabling the bladesupport members to be readily mounted upon the channel.
- the blade-guide members may be provided with vertical slots in which the bolt extends, excessive tightening being prevented by an appropriate spacer.
- Yet another feature of the invention resides in the provision of ball joints or univeral bearing seats at each end of the tie rod which may be formed with a nut or bolt arrangement at each end to enable mounting and dismounting of the assembly more readily.
- the nut or bolt arrangements moreover, narrow the assemblies to be tied together into a closed system and enable the assemblies to be drawn together to minimize spacing between them.
- the tie rods should be composed of a material and dimensioned such that they are elastically bendable and have high tensile strength and large force constants (spring force) so that the end segments may be deflected relative to the central segment, as previously described with the tie rod assuming a corresponding curvature.
- the segments may, moreover, be provided with at least one longitudinal slot open in the direction of the rail, channel or conveyor trough through which the return pass of the chain extends.
- the lower edge of the slot may be offset somewhat inwardly of the upper or shielding edge, the latter limiting entry of particles into the chain slot.
- the lower edge may serve as an overflow enabling particles to discharge from the slot.
- the position of this lower edge is se lected such that a portion of the particles remain in the upper chain-guide slot to serve as a lubricant capable of damping the noise produced by the planer chain.
- the longitudinal slot arrangement also enables the chain and any connecting elements to pass through simultaneously and thus allows for rapid feedthrough of the chain and any connecting elements simultaneously for rapid repair at any location.
- the system not only reduces wear and provides a simple but rapidly operating planer, even when the blades are tilted with respect to the guide channel or rail, but also provides a relatively narrow mounting arrangement for the planer blades and excludes lifting of the conveyer trough with minor variations in ground contour. Even in hills and valleys of the ground surface, the blades, which may be of the type described in the aforementioned application and patents, remain in engagement with the ground in saddle shaped regions, as well as in troughs, all such movements being readily accommodated and an especially stable planer-guide arrangement thereby provided.
- the blade arrangement has a caterpillar-like accommodation to the ground.
- FIG. 1 is a somewhat diagrammatic side-elevational view of a coal excavator, planer-blade assembly according to the present invention, seen from the guided or conveyer side along a linear portion of its path;
- FIG. 2 is a view similar to FIG. 1 showing the travel of the scraper around a curved portion of the path;
- FIG. 3 is a detail view, also in elevation and from the conveyor or guided side, of the connection between two segments of the scraper of FIGS. 1 and 2;
- FIG. 4 is a cross-sectional view taken along the line IV IV of FIG. 3;
- FIG. 5 is a front-elevational view of a central segment of portion of the scraper, parts in front of the viewing plane being shown in dot-dash or phantom lines;
- FIG. 6 is a side view (from the trough or guided side) of one of the terminal or end segments, partly broken away and drawn to an enlarged scale;
- FIG. 6A is a cross-sectional view taken along a vertical plane VI VIA of FIG. 6;
- FIG. 7 is an enlarged detail view of the coupling member for the parts of the coal scraper.
- the present invention is directed to improvements in coal scrapers, chisels and excavators of the type which are carried by a chain along a closed path and along the edge or surface ofa flight conveyer, bucket conveyer or the like for excavating coal or other mineral matter from a mine seam or wall, depositing the detritus and valuable material thus removed from the cut upon the conveyor and carrying the mineral matter to wagons, trucks or cars for removal from the excavation site.
- the blade configuration of the chisel may be that of the earlier application and patents mentioned above as can be the drive, conveyer arrangement etc.
- the apparatus in which the cutting tool of the present invention is used, therefore, can be generically described as a coal planer" of the chain-drive type.
- planer blades are spaced along a chain and project from the machine platform (conveyer trough) upon which they are mounted, to chisel the coal from the side of the wall and floor as the machine is moved parallel to the wall across the floor.
- FIGS. 1 and 2 we have shown, in diagrammatic form, the edge of the conveyer pan or tray 2, along which the planer blades 1 are adapted to move.
- the edge of the tray comprises a pair of upstanding flanges 2a and 2b whose surfaces 2c and 2d cooperate with the guide profile 3 of each blade, the latter being positioned by and displaceable along the guide profiles and, therefore, along the edge of the tray whose flat central portion 2e, shown only in part, guides a flight conveyor of the type described in the above-mentioned copending application, the blades of the flight conveyor being retained by inwardly turned leads such as that shown at 2fin FIG. 6A.
- the surfaces 20 and 2d may be profiled complementarily to the surface 3 (FIG. 5) to positively position the scraper blades in the vertical direction.
- each planer blade assembly extends over a section 4 or 5 of the conveyer trough and comprises three planer guide segments 6, 7, 8, including stress-absorbing end segments 6 and 8 adapted to withstand the impact or longitudinal stress transferred along the planer blade chain and the central segment 7 which has a length twice that of the length of the end segments 6, 8.
- each planer-blade assembly is aligned and held together at least in part by a centering rod 9 extending through each end member and central member of the assembly and the adjacent assembly and anchored with freedom of swivel movement at its ends to the terminal segments 6 and 8 as will be apparenthereinafter.
- the segments 6 and 7, 7 and 8 are also joined together by means of hinges 10 whose pivot axes run perpendicular to the lonitudinal direction and the direction of elongation of the conveyer trough.
- the pivots 10 are located closer to the impact surface of the trough (FIGS. II and 2) than the rods 9.
- the rods 9 link the segments of successive assemblies together.
- the hinges 10 include outwardly projecting hinge eyes 11 carried by the central segment 7 and bifurcated lugs 12 carried by the outer segments 6 and 8 and adapted to receive a pintle when the corresponding eye 11 is introduced into registry with the lugs.
- the bifurcated lugs 12 are also provided with extensions 13 which are received in corresponding recesses 14 above and below the hinge eye 11 of the central segment 7.
- Central segment 7 and terminal segments 6 and 8 are also connected together by centering pins 15 adapted to limit the angle to which one segment can be rotated with respect to the other about the hinge 10.
- the guide means includes a projection 16, e.g. a rib, which is received in a lateral channel 17 along the conveyer tray and formed on each or some of the segments of each planer-blade assembly.
- the projection 16 of the end segments 6 and 8 provide relatively large amounts of play S in the channel 17.
- Members 16 constitute canting-limiting abutments which prevent excess displacement of any one segment in the channel 17. The abutments, therefore, ensure uniform deflection of the elastically deflectable, high-tensile-strength rod 9.
- each assembly is positioned in rail channel 17 by a plate 18 of generally rectangular configuration (see FIGS. 6 and 6A) which is bolted in place on each of the segments 6 8 by a bolt arrangement 19 and is received in the channel 17 with minor clearance.
- a plate 18 is of generally trapezoidal crosssection (FIG. 6A) to conform to the longitudinal flanks of the channel 17 and is received therein without any tendency to rotate about the axis of bolt arrangement 19 and positions the segments while enabling canting thereof about a longitudinal axis as will be apparent from FIG. 6A, and permitting vertical movement.
- the bolt arrangement 19 comprises a bolt 19a whose head 19]; is received within the channel and defines the axis 19c, such canting being limited exclusively by the abutment formation 16.
- the head 19b may be hexagonal or square and is formed axially outwardly of a square (prismatic) shoulder 19d received within a rectangular (complementary) cutout 18a of plate 18.
- the shank 22 of the bolt extends through a spacer sleeve 21 and a vertical slot 20 in the guide members 3 which carry the planer blades as noted earlier.
- the sleeve 21 is received with clearance in the slot 20 and has a head 21a overlying this slot and extending therebeyond in the direction parallel to the channel 17.
- a nut l9e clamps the spacer sleeve or bushing 21 against the plate 18.
- a slight clear ance a is thusprovided between the outer face of the web of members 3 and the inner face of the head or flange 21a of the spacer.
- the slot 20 is dimensioned to receive the spacer 21 with the clearance S above and below the spacer in the median position thereof. As a consequence, the members 3 may ride up and down within the play i S along the rail formed at 2.
- the resiliently deflectable'rod 9 is secured to the central segments 7 of adjoining assemblies by swivel connections or ball joints as best seen in FIG. 7.
- Each such connection represented generally at 3, comprises a segmentally spheroidal seat 24 formed in a wall 24a of the central segment 7 around a bore 24b through which the rod 9 passes with a clearance B.
- the rods 9 can thus be deflected into the arcuate configuration illustrated in FIG. 2 without significant strain at each extremity.
- FIGS. 4 and 5 show the members 3 in profile and it can be seen that an upper longitudinally extending chain-receiving passage 27 is formed as a laterally open slot therein.
- the return pass 27a of the chain extends through this passage which can be formed as a brake preventing free movement of the chain therein by the viscous drag and friction of powdered mineral matter collected in the passage 26.
- the latter is laterally open at 260 in a longitudinal mouth whose lower edge 28 acts as a weir. Excess comminuted detritus passes over the weir.
- the members 3 form guides for the planer blades 1 and their profiled carriers 33 when the latter are mounted thereon.
- the members 3 act solely as vertically shiftable and limitedly cantable guides for the planer blades so that the latter ride along these members as if they are caterpillar tracks accommodating dips and rises in the terrain.
- a planer-type excavator comprising a conveyer through having a longitudinal rail extending therealong, and a planer-blade guide assembly mounted on said rail and forming a guide surface for the planer blades, the improvement wherein said rail has a longitudinally extending channel and said assembly comprises a plurality of groups of guide segments, having respective formations engaging with vertical play in said channel, means connecting said segments of each group together in succession at least along an impactreceiving side for limited relative canting movement of successive segments and a rod connecting at least adjacent end elements of successive groups together with said vertical play.
- a planer-type excavator comprising a conveyer through having a longitudinal rail extending therealong, and a planer-blade guide assembly mounted on said rail and forming a guide surface for theplaner blades, the improvement wherein said assembly comprises a plurality of guide segments, and means connecting said segments together in succession at least along an impact-receiving side for limited relative canting movement of successive segments, the lastmentioned means including respective hinges articulating a pair of end segments to a central segment close to said side, and a resiliently deflectable rod passing through at least one of said segments and anchored to another of said segments and arcuately deflectable upon stressing from said side for maintaining said segments normally in substantial alignment, said rod extending generally parallel to said rail.
- hinges include a lug extending in a longitudinal direction generally parallel to said rail from opposite ends of each central segment and a fork receiving the respective lug and formed on each of said end segments, said forks and the respective lugs being pivotally interconnected.
- each central segment is formed with a pair of recesses flanking each of its said lugs above and below the latter, said forks having respective extensions received within said recesses with limited play.
- each of said segments is provided with a laterally open longitudinally extending guide slot, further comprising a chain having a return pass traversing said slot.
Landscapes
- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Chain Conveyers (AREA)
- Screw Conveyors (AREA)
Abstract
A mine excavator such as a coal planer comprising a flight-type conveyor along the periphery of the conveyer trough or rail of which planer blades are provided to remove coal from the walls and floor of the excavation and direct the mass onto the conveyer. The guiding system for the planer blades comprises articulated guide segments mounted along the rails at the sides of the conveyer trough, limitedly movable in the vertical plane and grouped to include a pair of end segments separated by a central segment whose length is twice that of the end segments. The segments are hinged for relative angular movement about horizontal axes close to the floor-engaging (stress or impact) side of the assembly while successive pairs of central segments are interconnected by high-force constant flexing rods traversing the intervening end segments of two successive sets. The segments are held in a channel of the conveyer pan with limited freedom of up and down movement and are enabled to cant in a plane parallel to the rails.
Description
States Patent Braun et al.
GUIDE SYSTEM FOR MINE-PLANET! BLADES Inventors: Gert Braun; Ernst Braun, both of Essen-Heisingen, Germany Assignee: Halbach & Braun,
Wuppertal-Barmen, Germany Filed: Feb. 4, 1972 Appl. No.: 223,661
[ Jan.8,1974
Primary ExaminerErnest R. Purser Att0rney-Karl F. Ross 5 7] ABSTRACT A mine excavator such as a coal planer comprising a flight-type conveyor along the periphery of the conveyer trough or rail of which planer blades are provided to remove coal from the walls and floor of the excavation and direct the mass onto the conveyer. The guiding system for the planer blades comprises articulated guide segments mounted along the rails at the sides of the conveyer trough, limitedly movable in the vertical plane and grouped to include a pair of end segments separated by a central segment whose length is twice that of the end segments. The segments are hinged for relative angular movement about horizontal axes close to the floor-engaging (stress or impact) side of the assembly while successive pairs of central segments are interconnectedby high-force constant flexing rods traversing the intervening end segments of two successive sets. The segments are held in a channel of the conveyer pan with limited freedom of up and down movement and are enabled to cam in a plane parallel to the rails.
14 Claims, 8 Drawing Figures VA V/x W A W WSW wswsw @vwxw w PATENTEU 91-974 SHEET 1 OF 5 kw QM PMENTEBJAH 8 I974 SHEET 5 BF 5 m wI I GUIDE SYSTEM FOR MINE-PLANER BLADES CROSS-REFERENCE TO RELATED APPLICATION The present invention relates to our copending U.S. Pat. application Ser. No. 201,430 filed Nov. 23, 1971 and entitled PLANER DRIVE SYSTEM. That application refers to commonly assigned U.S. Pat. No. 3,399,757; 3,419,126; 3,431,024 and 3,499,683.
FIELD OF THE INVENTION Our present invention relates to coal planers and, more particularly, to a system for guiding the planar blades along the guide channels or rails'of a flight conveyor or similar appliance for removing excavated material, especially in single-chain flight conveyors.
BACKGROUND OF THE INVENTION A planer for use in mine and other excavators, generally comprises a conveying unit adapted to carry the excavated mineral matter and detritus away from the excavation site to a remote processing location, either directly or through the intermediary of other conveying means such as trucks, rail carriers, belts, buckets and the like. The planer is provided with planer blades along the edge of its conveyer which chisel, scrape or otherwise penetrate the wall and floor surfaces as the planer is advanced to dislodge chunks of coal, with or without inutile debris and detritus which is scooped up by the planer blades or by additional blades suitably provided and deposited upon the conveyer. The conveyer generally is of the flight type, i.e., comprises an elongated pan, tray or trough, reinforced at the edges by rails along which the planer blades are guided. Of special interest to the present invention is a singlechain flight conveyer, whereby the flights of the conveyer are interconnected by a single chain generally passing through the middle of the flights. In this flight conveyer, the conveyer trough may have a generally flat floor along which the mineral matter is scraped by the flights.
Various blade arrangements, chain connections, blade assemblies and flight-conveyor constructions have been described in the patents and copending application mentioned above, as have improvements in the chain drive. In spite of the fact that wear can be reduced by mounting replaceable guide members upon which the blades ride and which are mounted along the rails at the sides of the conveyer trough, considerable difficulty has been encountered with conventional planer-blade structures.
With guide profiles for the planer blades, i.e., members whose crosssection is generally complementary to that of the rail and which is mounted thereon and carry the slidable planer blades which are of a length equal approximately to the length of the stroke of the reciprocating planer or a substantial portion of the length of the transport path along the trough, difficulties have been encountered. This is particularly the case when the conveyer is exposed to stress or impact in following the contours of the ground surface. Under these circumstances, the existing arrangements are ineffective because of the excessive length of the planer-blade supports or guides. It should be noted that the introduction of bent or curved paths for the planer blades has led to damage of conveyer troughs, excessive wear of the rails and the supports, and even to the generation of prohibitive noise volumes. Considerable stress is applied in the scraper itself and significant wear develops at any point of path flexion or deviation from the linear.
OBJECTS OF THE INVENTION It is the principal object of the present invention to provide an improved scraper or planer arrangement, especially a coal planer with a single-chain'flight conveyer, whereby the aforementioned disadvantages can be obviated.
Another object of the invention is to provide an improved blade-guide system for a single-chain flight conveyer coal scraper.
Yet another object of our invention is the provision of improved means for mounting and guiding scraper blades for apparatus of the class described.
SUMMARY OF THE INVENTION These objects are attained in accordance with the present invention, in an arrangement for guiding the coal planers ofa single-chain flight-conveyer apparatus in which maximum planing speed can be maintained with optimum planing characteristics and low wear, even when the conveyer is carried over undulated terrain and especially hills and valleys (heights and dips) in the excavated region. This has been achieved, according to the principles of this invention, by providing the planer-blade guide as a plurality of hingedly interconnected segments, coupled together so as to be biased resiliently into mutual alignment by a coupling rod common to at least two of the three segments forming each blade carrier assembly. The articulations between adjoining segments preferably allow relative angular displacement about axes parallel to the surface engaged by the blades or the blade carrier segments, e.g. parallel to the horizontal when the articulations are to enable the blades to ride over changing terrain. Advantageously, the guide means for the blades is so constructed and arranged as to allow relative movement of the trough and the blade carrier in a direction perpendicular to the aforementioned axes, i.e., in the vertical direction in the case described.
Preferably, each blade-guide assembly comprises three blade-guide segments including a pair of relatively short outer segments (end segments), and an intermediate relatively long segment (central segment) whose length is approximately twice that of each of the outer or end segments. Each of the latter segments thus has a length which is approximately half that of the central segment. While the three segments of each assembly are hingedly interconnected close to the impacting side of the assembly, i.e., the bottom when the assemblies are to compensate for varying ground contours, the centering and alignment member may be a rod or bar traversing at least two segments and preferably anchored by ball joints in a pair of central segments of two adjoining assemblies while traversing the end segments between the central segments with a minimum of contact. The rods thus interconnect the adjacent assemblies.
The end segments of each of the blade-support assemblies are hinged or articulated to the central segment for relative rotation about axes orthogonal or perpendicular to the longitudinal direction of the guide rails and define, together with the central segments, an assembly length equal to the stroke of the planer blades. The end segments are thus enabled to pivot, relative to the central segment, through several degrees and the array of blades can, together with the blade guides be bent through relatively large angles distributcd over the several assemblies, thereby enabling the blade arrays to adjust to the ground contours more readily than has hitherto been the case. The end segments, of course, not only are able to pivot with respect to one another (e.g. the end segments of adjoining assemblies can be tilted with respect to one another) so that the tilt of any one segment within the guide channel may be reduced, e.g. dimensioned to a half or a third of the usual canting motion for a given change in contour.
According to another feature of the invention, the central segment of each assembly is provided at its ex tremities, close to the impact-receiving (ground) surface with hinge lugs which project longitudinally at either end and are received between bifurcated lugs or forks of the end segments. The latter may be received within recesses of the central segment and the single lugs of the latter may be received within a recess of the central segment to create a compact assembly with minimal spacing between the confronting faces of end and central segments. In addition, we provide above and below the articulation or hinge, respective recesses in the central segment and corresponding protuberances of the end segments such that the protuberances extend into the recesses and define therein the articulation play establishing the maximum relative angle of tilt. These formations function as force-transmitting elements when the tilt has reached the maximum. In addition, the central and end segments can be provided with centering or aligning pins which also establish the angular play and enable the segments to be aligned for mounting.
The central and end segments may be provided with abutment projections which can extend into a laterally open channel formed in the rail of the conveyor trough and which are dimensioned to allow the limited angular play therein mentioned earlier. The abutment projections also have the function of distributing the bending action more uniformly over the length of the tie rod interconnecting the assembly and preferably are formed with screw or bolt arrangements enabling the bladesupport members to be readily mounted upon the channel. To this end, the blade-guide members may be provided with vertical slots in which the bolt extends, excessive tightening being prevented by an appropriate spacer.
Yet another feature of the invention resides in the provision of ball joints or univeral bearing seats at each end of the tie rod which may be formed with a nut or bolt arrangement at each end to enable mounting and dismounting of the assembly more readily. The nut or bolt arrangements, moreover, narrow the assemblies to be tied together into a closed system and enable the assemblies to be drawn together to minimize spacing between them.
Of course, the tie rods should be composed of a material and dimensioned such that they are elastically bendable and have high tensile strength and large force constants (spring force) so that the end segments may be deflected relative to the central segment, as previously described with the tie rod assuming a corresponding curvature. The segments may, moreover, be provided with at least one longitudinal slot open in the direction of the rail, channel or conveyor trough through which the return pass of the chain extends. The lower edge of the slot may be offset somewhat inwardly of the upper or shielding edge, the latter limiting entry of particles into the chain slot. The lower edge may serve as an overflow enabling particles to discharge from the slot. In general, the position of this lower edge is se lected such that a portion of the particles remain in the upper chain-guide slot to serve as a lubricant capable of damping the noise produced by the planer chain. The longitudinal slot arrangement also enables the chain and any connecting elements to pass through simultaneously and thus allows for rapid feedthrough of the chain and any connecting elements simultaneously for rapid repair at any location.
We have found that the system not only reduces wear and provides a simple but rapidly operating planer, even when the blades are tilted with respect to the guide channel or rail, but also provides a relatively narrow mounting arrangement for the planer blades and excludes lifting of the conveyer trough with minor variations in ground contour. Even in hills and valleys of the ground surface, the blades, which may be of the type described in the aforementioned application and patents, remain in engagement with the ground in saddle shaped regions, as well as in troughs, all such movements being readily accommodated and an especially stable planer-guide arrangement thereby provided. In summary, the blade arrangement has a caterpillar-like accommodation to the ground.
DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:
FIG. 1 is a somewhat diagrammatic side-elevational view of a coal excavator, planer-blade assembly according to the present invention, seen from the guided or conveyer side along a linear portion of its path;
FIG. 2 is a view similar to FIG. 1 showing the travel of the scraper around a curved portion of the path;
FIG. 3 is a detail view, also in elevation and from the conveyor or guided side, of the connection between two segments of the scraper of FIGS. 1 and 2;
FIG. 4 is a cross-sectional view taken along the line IV IV of FIG. 3;
FIG. 5 is a front-elevational view ofa central segment of portion of the scraper, parts in front of the viewing plane being shown in dot-dash or phantom lines;
FIG. 6 is a side view (from the trough or guided side) of one of the terminal or end segments, partly broken away and drawn to an enlarged scale;
FIG. 6A is a cross-sectional view taken along a vertical plane VI VIA of FIG. 6; and
FIG. 7 is an enlarged detail view of the coupling member for the parts of the coal scraper.
SPECIFIC DESCRIPTION As noted earlier, the present invention is directed to improvements in coal scrapers, chisels and excavators of the type which are carried by a chain along a closed path and along the edge or surface ofa flight conveyer, bucket conveyer or the like for excavating coal or other mineral matter from a mine seam or wall, depositing the detritus and valuable material thus removed from the cut upon the conveyor and carrying the mineral matter to wagons, trucks or cars for removal from the excavation site. The blade configuration of the chisel may be that of the earlier application and patents mentioned above as can be the drive, conveyer arrangement etc. The apparatus in which the cutting tool of the present invention is used, therefore, can be generically described as a coal planer" of the chain-drive type. For the most part, the planer bladesare spaced along a chain and project from the machine platform (conveyer trough) upon which they are mounted, to chisel the coal from the side of the wall and floor as the machine is moved parallel to the wall across the floor.
In FIGS. 1 and 2, we have shown, in diagrammatic form, the edge of the conveyer pan or tray 2, along which the planer blades 1 are adapted to move. The edge of the tray comprises a pair of upstanding flanges 2a and 2b whose surfaces 2c and 2d cooperate with the guide profile 3 of each blade, the latter being positioned by and displaceable along the guide profiles and, therefore, along the edge of the tray whose flat central portion 2e, shown only in part, guides a flight conveyor of the type described in the above-mentioned copending application, the blades of the flight conveyor being retained by inwardly turned leads such as that shown at 2fin FIG. 6A. The surfaces 20 and 2d may be profiled complementarily to the surface 3 (FIG. 5) to positively position the scraper blades in the vertical direction.
The scraper blades 1 are subdivided over the length of the displacement path into segments 6, 7 and 8, best seen in FIGS. 1 and 2, the segments traveling along the straight section of the path 4 and the curved section 5 thereof. Segments 6 and 8 are, for the purposes of the present invention, described hereinafter as terminal or end segments while member 7 will be described as a central segment. In other words each planer blade assembly extends over a section 4 or 5 of the conveyer trough and comprises three planer guide segments 6, 7, 8, including stress-absorbing end segments 6 and 8 adapted to withstand the impact or longitudinal stress transferred along the planer blade chain and the central segment 7 which has a length twice that of the length of the end segments 6, 8. The three segments of each planer-blade assembly are aligned and held together at least in part by a centering rod 9 extending through each end member and central member of the assembly and the adjacent assembly and anchored with freedom of swivel movement at its ends to the terminal segments 6 and 8 as will be apparenthereinafter. The member 9, which can flex as a comparison of FIGS. 1 and 2 will show, traverse the central segment 7 with only limited engagement therewith. The segments 6 and 7, 7 and 8 are also joined together by means of hinges 10 whose pivot axes run perpendicular to the lonitudinal direction and the direction of elongation of the conveyer trough. The pivots 10 are located closer to the impact surface of the trough (FIGS. II and 2) than the rods 9. As is also apparent from FIGS. 1 and 2, the rods 9 link the segments of successive assemblies together.
The hinges 10 include outwardly projecting hinge eyes 11 carried by the central segment 7 and bifurcated lugs 12 carried by the outer segments 6 and 8 and adapted to receive a pintle when the corresponding eye 11 is introduced into registry with the lugs. The bifurcated lugs 12 are also provided with extensions 13 which are received in corresponding recesses 14 above and below the hinge eye 11 of the central segment 7. Central segment 7 and terminal segments 6 and 8 are also connected together by centering pins 15 adapted to limit the angle to which one segment can be rotated with respect to the other about the hinge 10. The guide means includes a projection 16, e.g. a rib, which is received in a lateral channel 17 along the conveyer tray and formed on each or some of the segments of each planer-blade assembly. The projection 16 of the end segments 6 and 8 provide relatively large amounts of play S in the channel 17. Members 16 constitute canting-limiting abutments which prevent excess displacement of any one segment in the channel 17. The abutments, therefore, ensure uniform deflection of the elastically deflectable, high-tensile-strength rod 9.
The segments of each assembly are positioned in rail channel 17 by a plate 18 of generally rectangular configuration (see FIGS. 6 and 6A) which is bolted in place on each of the segments 6 8 by a bolt arrangement 19 and is received in the channel 17 with minor clearance. A plate 18 is of generally trapezoidal crosssection (FIG. 6A) to conform to the longitudinal flanks of the channel 17 and is received therein without any tendency to rotate about the axis of bolt arrangement 19 and positions the segments while enabling canting thereof about a longitudinal axis as will be apparent from FIG. 6A, and permitting vertical movement. The bolt arrangement 19 comprises a bolt 19a whose head 19]; is received within the channel and defines the axis 19c, such canting being limited exclusively by the abutment formation 16. The head 19b may be hexagonal or square and is formed axially outwardly of a square (prismatic) shoulder 19d received within a rectangular (complementary) cutout 18a of plate 18. As a consequence, the plate 18 and the bolt 19a are nonrotatable with respect to one another. The shank 22 of the bolt extends through a spacer sleeve 21 and a vertical slot 20 in the guide members 3 which carry the planer blades as noted earlier. The sleeve 21 is received with clearance in the slot 20 and has a head 21a overlying this slot and extending therebeyond in the direction parallel to the channel 17. A nut l9e clamps the spacer sleeve or bushing 21 against the plate 18. A slight clear ance a is thusprovided between the outer face of the web of members 3 and the inner face of the head or flange 21a of the spacer. The slot 20 is dimensioned to receive the spacer 21 with the clearance S above and below the spacer in the median position thereof. As a consequence, the members 3 may ride up and down within the play i S along the rail formed at 2.
The resiliently deflectable'rod 9 is secured to the central segments 7 of adjoining assemblies by swivel connections or ball joints as best seen in FIG. 7. Each such connection, represented generally at 3, comprises a segmentally spheroidal seat 24 formed in a wall 24a of the central segment 7 around a bore 24b through which the rod 9 passes with a clearance B. A washer 25 having a surface 25a conforming to a spherical segment, with the same radius of curvature as seat 27, bears against the seat and is held against the shoulder 9a of the rod 9 by a castellated nut 9b which is threaded onto the extremity 9c of the rod and held in place by a pin 9d. The rods 9 can thus be deflected into the arcuate configuration illustrated in FIG. 2 without significant strain at each extremity.
FIGS. 4 and 5 show the members 3 in profile and it can be seen that an upper longitudinally extending chain-receiving passage 27 is formed as a laterally open slot therein. The return pass 27a of the chain extends through this passage which can be formed as a brake preventing free movement of the chain therein by the viscous drag and friction of powdered mineral matter collected in the passage 26. The latter is laterally open at 260 in a longitudinal mouth whose lower edge 28 acts as a weir. Excess comminuted detritus passes over the weir.
At the bottom of the members 3, there are provided substantially aligned passages 30 through which the forward pass 31 of the chain is guided to receive connecting elements 32 of the blade structure. It should be understood that the members 3 form guides for the planer blades 1 and their profiled carriers 33 when the latter are mounted thereon. In other words, the members 3 act solely as vertically shiftable and limitedly cantable guides for the planer blades so that the latter ride along these members as if they are caterpillar tracks accommodating dips and rises in the terrain.
We claim:
1. In a planer-type excavator, comprising a conveyer through having a longitudinal rail extending therealong, and a planer-blade guide assembly mounted on said rail and forming a guide surface for the planer blades, the improvement wherein said rail has a longitudinally extending channel and said assembly comprises a plurality of groups of guide segments, having respective formations engaging with vertical play in said channel, means connecting said segments of each group together in succession at least along an impactreceiving side for limited relative canting movement of successive segments and a rod connecting at least adjacent end elements of successive groups together with said vertical play.
2. In a planer-type excavator, comprising a conveyer through having a longitudinal rail extending therealong, and a planer-blade guide assembly mounted on said rail and forming a guide surface for theplaner blades, the improvement wherein said assembly comprises a plurality of guide segments, and means connecting said segments together in succession at least along an impact-receiving side for limited relative canting movement of successive segments, the lastmentioned means including respective hinges articulating a pair of end segments to a central segment close to said side, and a resiliently deflectable rod passing through at least one of said segments and anchored to another of said segments and arcuately deflectable upon stressing from said side for maintaining said segments normally in substantial alignment, said rod extending generally parallel to said rail.
3. The assembly defined in claim 2 and mounted on said rail together with at least one other similar adjacent assembly, said rod interconnecting the central seg-' ments of both said assemblies.
4. The assembly defined in claim 3 wherein said hinges include a lug extending in a longitudinal direction generally parallel to said rail from opposite ends of each central segment and a fork receiving the respective lug and formed on each of said end segments, said forks and the respective lugs being pivotally interconnected.
5. The assembly defined in claim 4 wherein each central segment is formed with a pair of recesses flanking each of its said lugs above and below the latter, said forks having respective extensions received within said recesses with limited play.
6. The assembly defined in claim 2, further comprising centering pins received between each end segment and the respective central segment for limiting the relative canting of each end segment and the respective central segment.
7. The assembly defined in claim 2 wherein said rail is formed with a laterally open longitudinally extending channel, each of said segments having a lateral pr0jection received in said channel with limited play for restricting vertical displacement of said segment relative to said rail.
8. The assembly defined in claim 2 wherein said rail is formed with a laterally open channel and said segments are each provided with a plate received in said channel, and bolt means securing said plate to the respective segment while enabling limited vertical displacement of the segments relative to said rail.
9. The assembly defined in claim 2, further comprising a generally spheroidal joint connecting respective ends of said rod to each central segment.
10. The assembly defined in claim 9 wherein said rod is composed of a material having high tensile strength and spring force.
11. The assembly defined in claim 2 wherein each of said segments is provided with a laterally open longitudinally extending guide slot, further comprising a chain having a return pass traversing said slot.
12. The assembly defined in claim 11 wherein said slot is formed with a lower edge defining a weir across which excessive comminuted material collected in said slot is discharged.
13. The assembly defined in claim 12 wherein said segments are formed with a downwardly open passage receiving a forward pass of said chain.
14. The assembly defined in claim 13, further comprising scraper blades guided along said segments and having means extending into said passage and engaging said chain.
Claims (14)
1. In a planer-type excavator, comprising a conveyer through having a longitudinal rail extending therealong, and a planerblade guide assembly mounted on said rail and forming a guide surface for the planer blades, the improvement wherein said rail has a longitudinally extending channel and said assembly comprises a plurality of groups of guide segments, having respective formations engaging with vertical play in said channel, means connecting said segments of each group together in succession at least along an impact-receiving side for limited relative canting movement of successive segments , and a rod connecting at least adjacent end elements of successive groups together with said vertical play.
2. In a planer-type excavator, comprising a conveyer through having a longitudinal rail extending therealong, and a planer-blade guide assembly mounted on said rail and forminG a guide surface for the planer blades, the improvement wherein said assembly comprises a plurality of guide segments, and means connecting said segments together in succession at least along an impact-receiving side for limited relative canting movement of successive segments, the last-mentioned means including respective hinges articulating a pair of end segments to a central segment close to said side, and a resiliently deflectable rod passing through at least one of said segments and anchored to another of said segments and arcuately deflectable upon stressing from said side for maintaining said segments normally in substantial alignment, said rod extending generally parallel to said rail.
3. The assembly defined in claim 2 and mounted on said rail together with at least one other similar adjacent assembly, said rod interconnecting the central segments of both said assemblies.
4. The assembly defined in claim 3 wherein said hinges include a lug extending in a longitudinal direction generally parallel to said rail from opposite ends of each central segment and a fork receiving the respective lug and formed on each of said end segments, said forks and the respective lugs being pivotally interconnected.
5. The assembly defined in claim 4 wherein each central segment is formed with a pair of recesses flanking each of its said lugs above and below the latter, said forks having respective extensions received within said recesses with limited play.
6. The assembly defined in claim 2, further comprising centering pins received between each end segment and the respective central segment for limiting the relative canting of each end segment and the respective central segment.
7. The assembly defined in claim 2 wherein said rail is formed with a laterally open longitudinally extending channel, each of said segments having a lateral projection received in said channel with limited play for restricting vertical displacement of said segment relative to said rail.
8. The assembly defined in claim 2 wherein said rail is formed with a laterally open channel and said segments are each provided with a plate received in said channel, and bolt means securing said plate to the respective segment while enabling limited vertical displacement of the segments relative to said rail.
9. The assembly defined in claim 2, further comprising a generally spheroidal joint connecting respective ends of said rod to each central segment.
10. The assembly defined in claim 9 wherein said rod is composed of a material having high tensile strength and spring force.
11. The assembly defined in claim 2 wherein each of said segments is provided with a laterally open longitudinally extending guide slot, further comprising a chain having a return pass traversing said slot.
12. The assembly defined in claim 11 wherein said slot is formed with a lower edge defining a weir across which excessive comminuted material collected in said slot is discharged.
13. The assembly defined in claim 12 wherein said segments are formed with a downwardly open passage receiving a forward pass of said chain.
14. The assembly defined in claim 13, further comprising scraper blades guided along said segments and having means extending into said passage and engaging said chain.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19712105582 DE2105582C2 (en) | 1971-02-06 | Device for guiding a coal plow on the conveyor trough of a chain conveyor |
Publications (1)
Publication Number | Publication Date |
---|---|
US3784258A true US3784258A (en) | 1974-01-08 |
Family
ID=5797964
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00223661A Expired - Lifetime US3784258A (en) | 1971-02-06 | 1972-02-04 | Guide system for mine-planer blades |
Country Status (3)
Country | Link |
---|---|
US (1) | US3784258A (en) |
FR (1) | FR2124254B1 (en) |
GB (1) | GB1337701A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4082361A (en) * | 1975-07-10 | 1978-04-04 | Gebr. Eickhoff, Maschinenfabrik Und Eisengiesserei M.B.H. | Rack device for a mining machine |
US4278294A (en) * | 1978-12-23 | 1981-07-14 | Gert Braun | Guide-rail assembly for longwall mining apparatus |
US20070138086A1 (en) * | 2004-02-17 | 2007-06-21 | Pekka Tuomikoski | Scraper |
US9404240B2 (en) | 2013-11-07 | 2016-08-02 | Caterpillar Inc. | Bucket lip protection assemblies and lip adapters for same |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2590802A (en) * | 1947-05-23 | 1952-03-25 | Houilleres Bassin Du Nord | Pusher conveyer with sectional trough |
US3306664A (en) * | 1962-10-26 | 1967-02-28 | Gewerk Eisenhuette Westfalia | Articulatable planer guide arrangement |
-
1972
- 1972-01-06 GB GB57672A patent/GB1337701A/en not_active Expired
- 1972-01-24 FR FR727202199A patent/FR2124254B1/fr not_active Expired
- 1972-02-04 US US00223661A patent/US3784258A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2590802A (en) * | 1947-05-23 | 1952-03-25 | Houilleres Bassin Du Nord | Pusher conveyer with sectional trough |
US3306664A (en) * | 1962-10-26 | 1967-02-28 | Gewerk Eisenhuette Westfalia | Articulatable planer guide arrangement |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4082361A (en) * | 1975-07-10 | 1978-04-04 | Gebr. Eickhoff, Maschinenfabrik Und Eisengiesserei M.B.H. | Rack device for a mining machine |
US4278294A (en) * | 1978-12-23 | 1981-07-14 | Gert Braun | Guide-rail assembly for longwall mining apparatus |
US20070138086A1 (en) * | 2004-02-17 | 2007-06-21 | Pekka Tuomikoski | Scraper |
US9404240B2 (en) | 2013-11-07 | 2016-08-02 | Caterpillar Inc. | Bucket lip protection assemblies and lip adapters for same |
Also Published As
Publication number | Publication date |
---|---|
DE2105582B1 (en) | 1972-03-09 |
FR2124254B1 (en) | 1974-06-28 |
FR2124254A1 (en) | 1972-09-22 |
GB1337701A (en) | 1973-11-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4282968A (en) | Scraper-chain conveyor channel section | |
AU2008207682B2 (en) | A Conveyor Pan with Improved Edge Shaping | |
US3791054A (en) | Lip construction for bucketwheel excavators | |
US3784258A (en) | Guide system for mine-planer blades | |
US4006937A (en) | Carriage especially for use in mines | |
US5161858A (en) | Arrangement for guiding a cutting machine or similar mining machine at the conveyor trough of a drag-chain conveyor | |
US4515410A (en) | Rack assembly | |
US4063782A (en) | Long wall mining apparatus guide structure | |
US3869039A (en) | Scraper assemblies for scraper chain conveyors | |
US4715659A (en) | Mineral mining installations | |
US4632239A (en) | Scraper-chain conveyor channel section | |
GB2072126A (en) | Improvements in and relating to face conveyors | |
CN1201051C (en) | Digging chain for railroad engineering machine | |
US4159850A (en) | Mineral mining installation with face end winning | |
US4505379A (en) | Scrapers for scraper-chain conveyors | |
US4241824A (en) | Conveyors for use in mineral mining installations | |
US5088796A (en) | Seam-mining apparatus | |
US6073745A (en) | Adjustable yoke assembly | |
US3399757A (en) | Scraping conveyor | |
US5579896A (en) | System for arresting scraper-conveyor chain | |
US3455432A (en) | Armoured flexible conveyors | |
GB2038389A (en) | Apparatus and pans for guiding a cutting tool along a scraper chain conveyor | |
US8752906B2 (en) | Mining plough for plough systems and plough system for inclined formation | |
SU1419528A3 (en) | Plough unit for mining extraction of mineral resources | |
US3390915A (en) | Guided cutter chain for mining use |