Guide arrangement for a drum-type mineral cutting machine

A guide arrangement for a drum-type cutting machine is composed of a guide block cooperating with a guide rail and articulated at the lower end of a vertical guide arm of the cutting machine. The guide block has a pocket defined by lateral walls which receives the guide arm. A transverse bolt extends through the pocket in the guide block and is received snugly by a bore in the guide arm. One of the end regions of the bolt forms a pivot journal head with curved surfaces which is received in a pivot journal socket in one of the lateral walls of the pocket in the guide block. The other end of the transverse bolt fits with lateral play in a horizontal guide of the other lateral wall of the guide block. The inner surfaces of the lateral walls incline relative to a horizontal plane to permit the guide arm to cant about a vertical axis.

FIELD OF THE INVENTION
 The invention relates in general to mineral mining installations and, more
 particularly, to a guide arrangement for a drum-type mineral cutting
 machine usable, for example, in coal mining installations.
 BACKGROUND OF THE INVENTION
 In mineral mining installations it is well known to mount a drum-type
 cutting machine, such as a shearer, on a conveyor extending alongside a
 mineral, e.g. coal, face. The machine has a drive motor which rotates a
 toothed sprocket wheel which meshes with a stationary track, such as a
 chain, on the goaf side of the conveyor remote from the mineral face. As
 the sprocket wheel rotates the machine is driven back and forth above the
 conveyor to strip mineral from the mineral face with a rotating cutting
 drum and the conveyor then transports the mineral with a circulating
 scraper-chain assembly. To support and guide the machine a floor rail on
 the mineral face side of the conveyor supports running wheels whilst at
 the opposite goaf side the machine has vertically depending guide arms
 fitted with guide blocks which co-operate with guide projections slidably
 engaging in a guide rail supported on the conveyor. The guide blocks can
 clasp the guide rail substantially in the manner of a hook from above
 and/or below (see DE-PS 25 52 085, DE-PS 26 46 291, DE-OS 29 25 240).
 In order to adapt the guide blocks to the course of the conveyor which is
 not normally horizontal, the guide blocks are mounted on the guide arms of
 the cutting machine so as to be pivotal in height to a limited extent by
 means of horizontal transverse bolts.
 In order not only to provide compensation if the horizontal is not level,
 which is achieved by the pivotability of the guide block about a
 horizontal axis, but also to prevent jamming of the guide blocks when the
 conveyor does not extend exactly rectilinearly but adopts a curved course,
 for example if the individual conveyor pans snake, it is also already
 known additionally to make the guide blocks pivot around a vertical axis
 on the guide arm. Thus for this purpose the guide blocks according to
 DE-OS 196 33 491 are each provided with a vertical journal with which it
 is mounted so as to pivot rotatably to a limited extent in a journal
 socket on the guide arm. This known arrangement allows part rotation or
 pivoting of the guide block around a vertical as well as a horizontal axis
 in the manner of a universal joint so locking or clamping of the guide
 block and the guide rail can be substantially avoided. Nevertheless it has
 been found that, with the dimensions of the guide arm normally used, the
 forces occurring during cutting can barely be controlled with the known
 arrangement. Moreover, with a conventional material thickness of the guide
 arm of 120 mm and the necessary diameter of the vertical journal of 60 mm,
 there is a risk that the vertical bore on the guide arm will break out or
 deform and therefore will no longer be capable of holding the guide block
 with the necessary reliability.
 A guide arrangement is known from DE-GM 68 02 117. In this arrangement a
 transverse bolt is held rigidly in the guide arm and tapers at the two
 outer ends projecting from the guide arm substantially frusto-conically to
 the ends. These frusto-conically converging portions of the transverse
 bolt are held in cylindrical bores in the guide block with ample play and,
 owing to their configuration, allow limited pivotability of the guide
 block relative to the guide arm of the cutting machine both vertically and
 horizontally. The disadvantage of this arrangement resides mainly in the
 fact that guide block and transverse bolt only make loose contact with one
 another in each direction and this results in enormously high wear of the
 components because the transverse bolt can only be applied after
 overcoming the play existing on the respectively opposed surface regions
 of the bores in the guide block during each change of direction of travel.
 A further disadvantage of this arrangement is that the guide block can
 move not only in the vertical direction and the desired horizontal
 direction transversely to the direction of travel of the cutting machine
 but also in a horizontal direction parallel to the direction of travel of
 the cutting machine. As a result, the guide projection can more easily
 become disengaged from the guide rail arranged on the conveyor and
 reliable guidance of the machine is no longer ensured.
 SUMMARY OF THE INVENTION
 It is an object of the invention to avoid the aforementioned disadvantages
 and to provide a guide arrangement of the type mentioned at the outset
 which ensures good vertical and horizontal guidance of the cutting machine
 without leading to unacceptably high wear in the connection region between
 the guide block and guide arm.
 Another object of the invention is to avoid problems occurring as a result
 of the predetermined dimensions of the guide arms when using a separate
 vertical journal of the type known in the art.
 In accordance with the invention an improved guide arrangement comprises a
 guide block which is pivotally connected on a guide arm of the cutting
 machine for movement around a horizontal and a vertical axis and
 co-operates with a guide rail arranged on the conveyor. The guide arm fits
 into a pocket on the guide block and is secured therein by means of a
 transverse bolt. A pivot journal head is formed at one end region of the
 transverse bolt and the head is received pivotally relative to the guide
 block around a vertical axis in a pivot journal socket in a lateral wall
 of the pocket. A horizontal guide in the other lateral wall of the pocket
 receives the other end region of the transverse bolt with lateral play.
 With such an arrangement, the pivotability of the guide block around the
 horizontal axis transversely to the direction of travel of the machine is
 brought about by the transverse bolt which can be simply plugged into a
 bearing bore on the guide arm and is held rotatably and snugly therein.
 The pivotability around the vertical axis is brought about by the
 particular holding of the transverse bolt in the lateral walls of the
 pocket formed in the guide block. The end of the transverse bolt forming
 the pivot journal head of the transverse bolt is held rotatably around the
 vertical axis but otherwise substantially non-displaceably in the
 associated pivot journal socket, like a ball in a ball socket, whereas the
 other end of the transverse bolt can move to and fro in the direction of
 travel of the cutting machine in the horizontal guide. In contrast to the
 state of the art, the vertical pivot axis here does not extend through the
 guide arm of the cutting machine but is offset to the side of it. If the
 pivot journal socket is arranged on the goaf-side of the guide block in
 the vicinity of its guide projection, it is possible with the invention in
 a quite exceptionally advantageous manner to bring the vertical axis of
 rotation into close spatial proximity with the guide projection making
 guide engagement with the guide rail so that the constraining forces,
 which also occur with the articulated mounting of the guide block, between
 the conveyor and the cutting machine can be minimised.
 The pivot journal head preferably comprises lateral guide faces which are
 curved convexly so that it can pivot freely in the pivot journal socket
 and therefore always has at least linear contact with one side of the
 pivot journal socket. The pivot journal head and the pivot journal socket
 are preferably flattened in each case on their upper and lower sides, in
 other words at the roof and floor planes to ensure that the transverse
 bolt cannot rotate around its axis in the journal socket itself and also
 to prevent pivoting around a horizontal axis parallel to the direction of
 travel of the machine.
 The pivot journal socket can be provided on its underside with at least one
 outlet orifice through which fine dust entering the socket can be
 discharged.
 The transverse bolt is expediently secured in the pivot journal socket by
 means of a securing element which particularly advantageously consists
 substantially of a locking element which is arranged on the pivot journal
 head, to fit into the outlet orifice and comes into contact with a lateral
 wall of the outlet orifice during unintentional extraction or migration of
 the transverse bolt from the bearing bore on the guide arm or the pivot
 journal socket on the guide block and therefore positively prevents
 further extraction.
 The transverse bolt preferably forms, at its end fitting in the horizontal
 guide, a sliding block which is flattened at the top and bottom and is
 laterally displaceable in the horizontal guide.
 The lateral walls of the pocket confronting the guide arm preferably form
 inclined contact faces. It is particularly advantageous if the length of
 the horizontal guide and the angle of the contact faces are so dimensioned
 that, during the pivoting of the guide block around the vertical axis, the
 guide arm with its lateral faces comes into contact with some of the
 contact faces before the end of the transverse bolt sliding in the
 horizontal guide strikes a leading or trailing end of the horizontal
 guide. This design ensures that no forces are transmitted horizontally
 between the horizontal guide arranged on the mineral face-side of the
 guide block and the end of the transverse bolt which is displaceable to
 and fro therein, because they are absorbed completely by the lateral faces
 of the guide arm resting on the contact faces of the pocket. The
 horizontal guide and the sliding block of the transverse bolt displaceable
 therein can therefore be comparatively small in size.
 The pocket preferably has orifices for discharging fine dust which are
 expediently arranged in its interior space. Such a measure not only allows
 reliable discharge of the fine dust which would otherwise collect in the
 pocket but also advantageously reduces the weight of the guide block.
 The pivot journal socket can be designed in the form of a blind orifice in
 the associated lateral wall of the pocket so that the pivot journal socket
 is substantially closed and the admission of dust into the socket is
 minimised.
 In an advantageous development of the invention, the pivot journal head has
 a substantially vertically extending holding groove for the locking
 element which can be designed in the form of a hammer head screw the head
 of which is positively arranged in the holding groove. The transverse bolt
 can expediently be provided with a central through-bore for receiving the
 fastening screw bolt of the locking element which can then be clamped with
 a nut. The nut is released particularly easily from the side of the
 horizontal guide, that is from the mineral face-side.
 The transverse bolt can preferably be coupled at its end received in the
 horizontal guide to a bolt extractor which can be connected to the bolt
 end face and, for this purpose, can preferably be screwed on an extraction
 thread arranged on the bolt end face. It is then possible to fix the
 extractor on the fastening screw bolt and to pull the transverse bolt from
 the bearing bore once the locking element has been disengaged from the
 outlet orifice of the pivot journal socket.
 The vertical height of the transverse bolt end with the sliding block held
 in the horizontal guide is preferably at least as great as the diameter of
 the transverse bolt in the region of the bearing bore in the guide arm.
 The transverse bolt can then easily be inserted from the side of the
 horizontal guide for assembly of the guide block on the guide arm with its
 pivot journal head passing through the bearing bore into the pivot journal
 socket and can subsequently be locked therein.
 The guide faces of the pivot journal head are preferably also curved around
 the axis of the transverse bolt whereas the pivot journal socket forms
 lateral bearing faces for supporting the pivot journal guide faces which
 have a curvature adapted to the curvature of the guide faces. This
 configuration of pivot journal head and pivot journal socket allows
 problem-free transmission even of high intermittent loads of the type
 which can occur during operation.
 The guide block can be produced in one piece from cast steel and can
 preferably be used without further mechanical treatment.
 The invention may be understood more readily, and further features and
 advantages of the invention may become apparent from the following
 description.

DESCRIPTION OF PREFERRED EMBODIMENT
 FIG. 1 is a schematic representation of a mining installation of the type
 known per se with a shearer or drum-type cutting machine 1 and a conveyor
 2 which is arranged in an underground working alongside a mineral, e.g.
 coal face, (not shown) on the floor of the working. Essentially only the
 body 4 of the machine 1 is shown which spans the conveyor 2 in the manner
 of a bridge and is capable of travelling on its mineral face-side with
 wheels 5 on a floor rail 6. The floor rail 6 extends in the longitudinal
 direction of the face and is rigidly mounted laterally on the conveyor 2.
 The body 4 would mount a rotatable cutting drum (not shown) which serves
 to strip mineral from the mineral face as the machine 1 is moved along the
 conveyor 2. On the opposing goaf-side of the conveyor, the machine body 4
 is provided, at its leading and trailing end, with a respective vertically
 depending guide arm 7. At the lower end of each arm 7 there is pivotally
 connected a guide block 8 which leads with a guide projection 39 into a
 channel 20 in a guide rail 9 in the manner of a hook.
 The machine body 4 has a drive shaft for advancing the cutting machine 1.
 The drive shaft drives a toothed sprocket wheel 10 engaging with a rack 11
 or a stationary chain mounted in another channel formed in the guide rail
 9. The guide rail 9 is rigidly arranged on upstanding supports 13
 connected to the conveyor 2 on the goaf-side.
 The conveyor 2 is a scraper-chain conveyor with individual conveyor troughs
 or conveyor pans articulated to one another for slight vertical and
 horizontal mobility and a scraper-chain assembly is circulated along the
 pans in upper and lower runs.
 Installations of the type shown in FIG. 1 and described briefly
 hereinbefore are known in many designs and have already been used for a
 long time in underground mining. The present invention relates to the
 particular guide arrangement of the machine 1 composed of the guide blocks
 8 connected to the guide arms 7 and cooperating with the guide rail 9.
 As shown in FIG. 2, in the guide arrangement 14 according to the invention,
 the guide arm 7 is received in a pocket 15 provided in the guide block 8
 and is articulated to the guide block 8 by means of a transverse bolt 16
 in such a way that the guide block 8 can pivot relative to the guide arm 7
 around a horizontal axis 17 extending transversely to the direction of
 travel of the cutting machine 1. For this purpose, the transverse bolt 16
 is placed from the mineral face-side of the machine 1 though a suitable
 orifice 18 in a mineral face-side lateral wall 19 of the guide block 8
 laterally limiting the pocket 15 and through a bearing bore 20 in the
 guide arm 7. The goaf-side end region 21 of the transverse bolt 16 forms a
 pivot journal head 27 which fits into a suitable pivot journal socket 22
 in the goaf-side lateral wall 23 of the pocket 15 of the guide block 8.
 The bearing bore 20 has a slightly greater diameter than the transverse
 bolt 16 in the corresponding central region, so the bolt 16 can rotate
 freely in the bearing bore 20.
 The goaf-side end region 21 of the transverse bolt 16 which forms the pivot
 journal head 27 is flattened at its upper and lower sides 25, as shown
 best in FIGS. 2 and 4. The end region 21 forming the pivot journal head 27
 has lateral guide faces 29 which are curved convexly from vertical axes 28
 and of which the curvature is shown best in FIGS. 3 and 5. The guide faces
 29 are simultaneously also curved around the axis of the transverse bolt
 16, as shown in FIG. 6.
 Owing to the above-described design, the pivot journal head 27 can pivot
 freely to a limited extent in the associated pivot journal socket 22,
 similarly to a ball joint in a ball socket, about a vertical axis 38 (see
 FIG. 2) in the plane of the horizontal axis 17 of the transverse bolt 16,
 that is a plane parallel to the floor and roof.
 As shown in FIGS. 3 and 4, the lateral walls 19 and 23 of the pocket 15 are
 bevelled at their internal faces 30 directed toward the guide arm 7 so
 that the pocket 15 receives a diverging cross section issuing from the
 axis 17 of the transverse bolt 16 to the leading and trailing end 31 and
 32. The play between the guide arm 7 and the lateral walls 19, 23 of the
 pocket 15 thus increases uniformly on both sides of the guide arm 7
 starting from the transverse bolt 16 to the leading and trailing ends 31,
 32.
 As shown in FIG. 3, the orifice 18 in the mineral face-side lateral wall 19
 is a slot with a length 1 greater than the diameter d of the transverse
 bolt 16 in the region of the bearing bore 20. The slot orifice 18 thus
 forms a horizontal guide 33 for the mineral-face-side end region 34 of the
 transverse bolt 16. The mineral-face-side end region 34 of the transverse
 bolt 16 is designed in the manner of a sliding block 35 with a
 substantially rectangular cross section resting on the upper and lower
 bearing faces 36, 37 of the horizontal guide 33. The width b of the block
 35 however is smaller than the length 1 of the horizontal guide 33 so that
 it can move to and fro in the horizontal guide 33 in the longitudinal
 direction of the guide block 8 and in the direction of movement of the
 machine 1.
 The above-described arrangement and mounting of the transverse bolt 16 with
 its pivot journal head 27 in the pivot journal socket 22 and the sliding
 block 35 in the opposing horizontal guide 33 allows the guide block 8 not
 only to pivot around the horizontal axis 17 of the transverse bolt
 relative to the guide arm 7 but also to be movable around the vertical
 axis 38 (see FIG. 2). This vertical axis 38 extends through the pivot
 journal head 27 and the goaf-side lateral wall 23 and therefore extends at
 only at a small lateral distance from the guide rail 9 beneath which the
 guide block 8 engages with the guide projection 39 for guidance of the
 cutting machine 1. Jamming of the guide block 8 in the guide rail 9 is
 very reliably avoided owing to the spatial proximity of the vertical pivot
 axis 38 to the guide rail 9 and the guide projection 39 engaging
 therewith.
 FIG. 4 shows the guide block 8 mounted on the guide arm 7 in a position in
 which it has been pivoted by the maximum angle around the vertical axis 38
 relative to the guide arm 7. In this position, one part 23a of the inner
 surface 30 of the goaf-side lateral wall 23 and the diametrically opposed
 part 19b of the inner surface 30 of the mineral-face-side lateral wall 19
 act as contact faces which rest flat against the guide arm 7 whereas a
 correspondingly greater clearance has formed between the arm 7 and the
 other corresponding parts 19a, 23b of the inner surfaces 30 of the lateral
 walls 19, 23. It can be seen that the sliding block 35 of the transverse
 bolt 16 has not yet contacted the mineral-face-side lateral wall 19 at one
 end of the horizontal guide 33 but a small gap 40 still remains between
 the transverse bolt 16 and the lateral wall 19. This ensures that forces
 which occur as a result of intermittent stresses and can occur, for
 example during jamming of the guide block projection 39 in the guide rail
 9 and have to be diverted via the guide arm 7 into the machine body 4, are
 not transmitted from the transverse bolt 16 but are carried off directly
 via the flat contact faces 19b, 23a of the lateral walls 19, 23 of the
 pocket 15 into the guide arm 7.
 As shown best in FIGS. 5 and 6, the pivot journal head 27 is provided, at
 its end face 41, with a vertically extending groove 42 which serves for
 the positive reception of a locking element 43. In the embodiment
 illustrated, the locking element consists of a hammer head screw 44 of
 which the screw bolt 45 is plugged from the end face 41 of the transverse
 bolt 16 through a central through-bore 46 provided therein and is secured
 at the other end of the transverse bolt 16 at the end face of the sliding
 block 35 by a fastening nut 47. The hammer head 48 of the hammer head
 screw 44 projects downwardly beyond the pivot journal head 27 in the
 locked state and thus fits into an outlet orifice 49 arranged on the
 underside of the pivot journal socket 22 as shown in FIG. 2. To unlock the
 locking element 43 for removal of the guide block 8 connected to the
 transverse bolt 16 on the guide arm 7, the fastening nut 47 is simply
 released and the hammer head screw 44 is pushed into the through bore 46
 until the hammer head 48 disengages from the groove 42 at the opposite end
 and can therefore be rotated through about 90.degree. so that it no longer
 engages positively behind the stop face formed by the outlet orifice 49.
 The bolt 16 can then be drawn out. To simplify extraction of the
 transverse bolt 16, the mineral face-side end region of the bolt 16 on the
 end face of the sliding block 35 is provided with an extraction thread 52
 on which a suitable extraction tool (bolt extractor), not shown, can be
 screwed to enable both the bolt 16 and the locking element 43 to be drawn
 out.
 As shown in FIGS. 2, 3 and 4, a plurality of diverting orifices 51 for dust
 and fine material are provided in the guide block 8 on the underside of
 the pocket 15 which not only reliably prevent material from accumulating
 in the pocket 15 between the guide arm 7 and the lateral walls 23, 19 and
 thus from restricting the vertical and horizontal pivotability, but also
 help to keep the weight of the guide block 8 as low as possible. The
 outlet orifice 49 in the base of the pivot journal socket 22 can also
 discharge fine material.
 The entire guide block 8 can be produced from cast steel, and subsequent
 machining and other mechanical treatment can be dispensed with if casting
 moulds of sufficiently high accuracy are used.
 The invention is not restricted to the embodiment described and illustrated
 but many variations and modifications are possible without departing from
 the scope of the invention. For example, it would be conceivable to ensure
 the pivotal mounting of the pivot journal head 27 in the pivot journal
 socket 22 not by the special shape of the pivot journal head 27 itself
 which is able to move in a ball socket in the manner of a ball head in the
 embodiment, but to provide a separate stub axle which is placed through
 corresponding bores in the goaf-side lateral wall and the pivot journal
 head 27. The separate locking element 43 could also be dispensed with in
 such an embodiment because the transverse bolt 16 would then be held
 securely in the guide block 8 by the additional axle.
 Instead of securing of the transverse bolt 16 in the described embodiment
 by means of the hammer head screw 43, other methods of securing can be
 adopted. For example, a plate can cover the horizontal guide 33 on the
 exterior of the mineral-face-side lateral wall 19. This plate can be
 screwed on the outside of the wall 19 and then reliably prevents the
 transverse bolt 16 from becoming detached from the side. A plate of this
 type would also have the additional advantage that fine dust cannot enter
 the horizontal guide 33 from the mineral-face-side.