GB2140849A - Vertical-hook compound mat - Google Patents

Abstract

Compound mats for the lagging of the lining in the roadways of underground mining works and tunnel constructions are interconnected by a mat lock connection in which the longitudinal bars 3 are bent around at one end to form a vertical hook 10 and are made deformable at the other end. The deformation, in conjunction with the vertical hook 10 and a sliding ring 25, forms a "load distance part" 12. The deformation is produced by a plate 15 bend upwards on the other side of the sliding ring 25 and rigidly connected to longitudinal bar 4. When tractive forces occur the sliding ring 25 is drawn over the plate 15 and caused to perform deformation work. By varying the "troughing" of the plate 15, the plate thickness and the shape of the sliding ring 25 a characteristic curve advantageously corresponding to the prevailing conditions can be obtained. An alternative load distance part (not shown) takes the form of a wire which is bent hairpin-wise and which is bound to be compressed by the sliding ring when the compound mats are subjected to loads. The wire preferably forms a horizontal loop which is additionally bent out of the plane of the loop so that on the reversal of the deformation of the loop or wire an additional "knot'' is formed which increases the deformation resistance and keeps it constant over a long period. <IMAGE>

Description

SPECIFICATION Vertical-hook compound mat The invention relates to compound mat for the lagging of a steel roadway support system in underground mining and tunnel construction, consisting of intersecting longitudinal and transversal bars welded together at the intersection points, the longitudinal bars being bent over, at least at one end, to form vertical hooks bent out of the plane of the mat, while at their opposite end they bear a mat lock part which when the connection is made receives the corresponding vertical hook of the adjacent mat and which is mounted on the relevant end of the longitudinal bar in such a way as to be movable along the mat by tractive forces occurring.

The roadways opened up in underground mining and tunnel driving have to be supported and secured by steel linings, The lining arches used for this purpose are positioned at certain distances apart, these distances being secured by so-called lagging mats as a safeguard against crumbling rock. These mats are given a back filling of stones or other material in order to fillup the space between the lagging mats and the rock.

While the so-called "back laying mats" are simply placed behind tne lining arches and provided with hooks to connect them to the said arches and to one another, the so-called compound mats are so designed that when they are placed in one another and engage one another they in each case combine to form a "mat lock" in the longitudinal direction. Via this mat lock longitudinal forces can be absorbed. Among known compound mats are the so-called knot compound mats, the flat hook mats and similar lagging mats which in each case combine to form mat locks. From Ger.Unexamd Specn. 27 27 459 a compound mat is known of which the longitudinal bars are provided at one end with connecting hooks bent vertically out of the plane of the mat and at the other end, which is left straight, with clamping bodies termed "catches." In the process of connecting the mats together the clamping bodies are fastened to the longtiduinal bars on the formclosed principle via a bolt.

The compound mats first mentioned suffer from the drawback that the desired high absorption of longitudinal force only occurs gradually and does not begin until the deflection of the entire lagging mat increases. The curve in the graph for load and distance is very flat with these known types of mat and does not rise until after a deflection of 100-150 mm.

In the further course of the load and distance graph for these mats the curve undergoes a steep rise, practically as far as the breakage of the mat lock connection. This has the serious disadvantage that when impact pressure forces occur the rock may loosen, in some cases to a considerable extent, before the mat lock connection can take full effect and enable the impact pressure forces to be taken up by the lagging mat. The aim of mining engineers, however, is to enable any loosening of the rock, if possible, to be prevented by suitable measures in goodtime, i.e. where possible immediately. with the mats known from Ger.

Unexamd.Spe. 27 27 459 the curve in the load and distance graph is caused to ascend at an earlier stage, thanks to the form-closed connection obtained, but it only does so inadequately and in accordance with the prevailing conditions. It may be seen from the description that the aim is a different one, i.e. to provide a forward extending mat of which the forward extending length is to be adjustable.

The clamping forces are accordingly limited, and it should be borne in mind that this clamp connection has to be releasable in order to vary the forward extending length when required. With these mats likewise, therefore, the curve does not rise until a late stage, particularly since the clamping forces do not increase when tractive forces occur but undergo a disadvantageous reduction.

The purpose of the invention is to provide a compound mat for which the curve approximately corresponds to the ideal load and distance graph. By the ideal course for the curve is meant an initially steep rise up to a value of about 80 KN followed by a further ascent as far as the breakage of the mat lock connection.

The invention enables this object to be achieved as a result of the fact that the longitudinal bars are in each case deformable at the end opposite to the vertical hook and have a sliding ring which receives the vertical hook of the adjacent compound mat 2 and which is mounted so as to be displaceable in the longitudinal direction while subjected to tractive force and on the force-locked and/or form-closed principle in the direction of traction.

If two compound mats of this kind are connected together, i.e. if the vertical hook is introduced into the sliding ring and impact pressure forces occur, the curve in the load distance graph immediately rises steeply, because the ends of the longitudinal bars, undergoing immediate deformation, create a tractive connection taking immediate effect.

Any loosening of the rock is thus counteracted from the outset, so that a compound mat of this kind advantageously meets the demands made on it from the mining engineering point of view.

In one advantageous embodiment of the invention the longitudinal bars are straight at the end opposite to the vertical hook and rigidly connected to a U-shaped plate which surrounds the relevant end and which bears the sliding ring mounted thereon and sur rounding the plate and the inserted vertical hook and which is bent upwards at the end and beyond the sliding ring. This sliding ring is carried along by any tractive stress, this accompanying movement of the ring leading to a deformation of the U-shaped plate. The deformation occurring results in the desired initially very steep rise in the curve in the load and distance graph up to a very high value, before the breakage of the mat lock connection occurs at some later moment, as the curve continues to rise.By varying the "troughing" of the plate, the thickness of the metal and the shape of the sliding ring it is possible to select a characteristic curve appropriate to the prevailing conditions. For preference all longitudinal bars of a compound mat are provided with a plate and sliding ring of this kind, serving as a "load and distance part," so that the mat will be subjected to an even loading and its effect will be uniform. A compound mat of this kind can be advantageously extended forward without any obstacles, so that the working zone in the heading is secured at a still earlier stage.

To provide the desired high deformation forces immediately behind the sliding ring, the invention provides that the U-shaped plate is to be bent up on both sides by an angle of 15-30 behind the sliding ring or cut so as to widen out funnel-wise in the direction of the free end or provided with a conical opening or an increasing thickness or a rough surface.

The forces required for reversing the deformation of the U-shaped plate are too great that the curve in the load and distance graph is caused to take the desired steep course. It is perfectly possible to influence the course taken by the curve in the load and distance graph, e.g. by "troughing" the U-shaped plate to 15-30 preferably 20 , behind the sliding ring. By varying the "troughing" of the plate or by the other measures a short zone of more gradual ascent can be caused to precede the steep rise of the curve in the load and distance graph or the said rise itself can be varied.

If a compound mat of this kind is used as a forward extending mat it can advantageously be made resistant to blasting by welding a transversal bar onto the flanks at the free end of the U-shaped plate. This transversal bar prevents the U-shaped plates from undergoing deformation as a result of blasting or the impact of the rock caused by blasting, so that compound mats can be satisfactorily connected up to subsequent mats in due course without difficulty.

In a further version of the invention the longitudinal bars are bent over at both ends to form vertical hooks and the vertical hooks of adjacent compound mats can be connected to or secured in a plate which is folded U-wise and on the central part of which two sliding rings surrounding the vertical hooks are displaceable under a tractive load, and of which the parts situated beyond the sliding rings are bent upwards, thus having an upward bend, preventing the displacement of the sliding rings. This version offers the considerable advantage that no moments occur in the transmission of the tractive forces of the mats.

In addition, the transmission of the load is ensured independently of any welded connections and the individual compound mat takes the same form at both of its ends and is thus simpler to manufacture. In principle, in fact, an ordinary standard mat can be used ("back laying mat") with which the hooks are simply bent farther over so that the double-load part of the distance can be added and take effect.

The course taken by the characteristic curve can then be influenced by selecting the appropriate bending radius for the vertical hook.

Mat locks which are simple to produce and of which the effect can be influenced by the shape selected are advantageously obtainable if the longitudinal bars are constructed at the end opposite to the vertical hook, as a wire bent hairpin-wise in its plane, the sliding ring being displaceably mounted, enclosing the free end, on the wire bent hairpin-wise. This part, taking the form of a wire bent hairpinwise, is associated with the end of the longitudinal bar and can be sinply provided with a sliding ring, in which case the course taken by the curve in the load and distance graph can be easily varied within wide limits by the shaping, i.e. bending, of the wire.As a result of any impact pressure forces occurring the sliding ring will then cause the two parallel wires to undergo deformation until owing to the high deformation resistance they cannot be compressed any further at the closed end of the "hairpin". Particular advantages of this version are the simple method of production, the wide variety of shapes which can be selected for the "hairpin" and the possibility of influencing the result by the selection of the material. The wide variety of possible parameters enables compound mets of the vertical hook type to be manufactured and employed in the form which gives the best result for the case in question.

To enable the sliding rings to be mounted and to take effect in the most satisfactory manner possible, it is of advantage for the sliding ring to consist of a stamped metal part similar to a chain link. The sliding ring can then be produced by the stamping process to the desired shape and mounted on or connected to the longitudinal wire of the compound mat. This provides a further means of influencing the efficiency of the mat lock connection.

In addition to the various shapes which can be selected for the sliding ring a further possible version should be emphasized in which the sliding ring is constructed as a deformable body twisted to form three loops, the vertical hook being inserted into the middle loop. The vertical hook should then be introduced into the middle loop openings.

This has the advantage of producing additional clamping forces by which the efficiency of the mat lock connection is improved.

High deformation resistance can be obtained at an earlier stage, in a manner which largely relieves the stress on the welded connections, if the wire bent hairpin-wise and forming a horizontal loop is bent out of the plane in the zone of the loop and that the sliding ring is situated in'the bend and is constructed as a U-shaped flat part which is open towards the top and which in the built-in state is enclosed by the vertical hook of the adjacent lagging mat and the wire. This wire bent hairpin-wise can be very easily supplemented by the sliding ring which'can be loosely mounted thereon and facilitates the assembly operation, as the vertical hook can be simply "threaded" into the lagging mat already laid.Even with quite moderate impact pressure forces the sliding ring reverses the deformation of the wire bent hairpin-wise, causing the curve in the load and distance graph to take a favourable course. Owing to the shape selected for the "hairpin wire," which is additionally bent out of the plane, the deformation of the two parallel wires must necessarily undergo reversal, and it is of particular advantage that a knot forms which, after the defornation work which has accordingly occurred, leads to such high deformation resistance that the mat lock remains uniform until it is broken. This knotting additionally secures the mat assembly to a considerabe extent, with the further advantage that the wire, of which the deformation is reversed by the sliding ring, presses the free end of the vertical hook upwards, thus rendering the knot formation additionally secure.

It is of advantage for the sliding ring to be designed as a U-shaped flat part open towards the top. A sliding ring of this kind is simple to produce and mount, serving both as a clamp for the two wires of the loop and as a part producing the deformation work. If necessary, this flat part can also be clamped on afterwards, so that the assembly can be carried out in exact accordance with the prevailing conditions. When the lagging mat is suspended into position the Ushaped flat part at first serves as the sole connection between the two adjacent compound mats. It is a surprising fact that this comparatively weak member suffices to secure the connection between the two compound mats which is now reinforced by the knot formation.The simple construction of the flat part greatly simplifies the interconnection of adjacent compound mats or operation of hooking them into position, thus ensuring the over-all advantage of she compound mat of the vertical hook type, i.e. that the longitudinal bars of the interconnected compound mats are approximately symmetrical to one another. The compound mats to be interconnected therefore do not have to be offset laterally.

According to a further embodiment of the invention the sliding ring is construcsed as a continuous bar which is adapted to the width of the lagging mat and which is detachably mounted on the mat lock. This bar too acts as a sliding ring and reverses the deformation of the "hairpin" wire", thus producing the desired early deformation resistance.

The necessary operation of binding out the "hairpin wire" or the loop bent therefrom is advantageously performed, according to the invention, by providing the hairpin wire, in the zone of the loop, with three partial bends so designed that a straight section is left between the second and the third partial bend. This subdivision of the "folding" or bending simplifies the production process and the operation of fitting the individual end sections into one another, with the additional advantage of enabling the bar or the sliding ring to be suitably mounted in position. It is then of particular advantage to design the partial bends in such a way as to leave a straight section between the second and the third partial bend.The sliding ring or bar is placed and detachably affixed exactly in this section, so that this important part of the mat lock to be eventually formed is accurately positioned at all times.

A reliable and simple interconnection of the individual end sections of the compound mats and also an early effect are ensured by the fact that the second oblique-section is longer than the first oblique section by a distance at least equal to twice the thickness of the wire.

When the vertical hook is inserted or suspended into position the introduction of the free end of she vertical hook via the end of the "hairpin" is thus facilitated, and this positioning operation, effective for the formation of the knot, is reliably ensured. If it were too difficult to suspend the hook into position there would be arisk of the misuse of the ends of the "hairpin", for example, for this purpose.

The invention provides that for the suitable construction of the flat part the open flanks of the U-shaped flat part are constructed to project to beyond the edges of the wires of the straight section and to leave a gap equal to somewhat more than the thickness of the wire.

This ensures the reliable guiding of the flat part or sliding ring, in addition to which the operation of suspending the hook into position is not impeded by the open flanks. It also considerably reduces the risk of the U-shaped flat part being accidentally bent up. If the open flanks of the U-shaped flat part are constructed to leave a gap of which the width is somewhat greater than the thickness of the wire, then a certain guiding action is ensured even when the double hook is being hooked into position, subsequent accidental unhooking being prevented.

The invention is characterized in particular by the fact that it provides a compound mat having a mat lock connection with a favourable operating characteristic curve which, within certain limits, can in addition be influenced. With the compound mat according to the invention the curve in the load distance graph is caused to take an almost optimum course, inasmuch as it first rises very steeply, until a value of about 80 KN is reached, after which it rises more gradually, until the mat lock connection breaks. Impact pressure forces occurring are thus effectively intercepted almost immediately, so that little if any loosening of the rock can take place.Thanks to the special mat construction with the vertical hooks the individual compound mats can be installed in close succession even in the direction of the periphery of the roadway, thus rendering the securing function of the compound mats noticeably more effective. In extreme cases the mats can be arranged with the outer longitudinal bars adjacent to one another. It is to be regarded as a further considerable advantage that by reason of the mat lock construction adopted the last transversal bars can be positioned practically above the mat lock, which greatly improves the stability of such lagging mats and at the same time helps to secure the mat lock construction in relation to the rock.In the longitudinal direction of the mat likewise a compound mat of this kind can prove advantageousy inasmuch as when extended forward it continues to prove effective and fully capable of performing its function in the event of blasting operations. This is particularly due to the use of the spacers, which prevent a compound mat, once it has been inserted, from being thrust back into the Mat lock construction. It consists of items easy to produce and capable owing to their construction of influencing the course taken by the load distance curve. By the knot formation the high deformation resistance, taking place at an advantageously early stage, can be rendered effective over long distances and/or periods and evenly maintained.

Further details and advantages of the object of the invention will emerge from the following description of the relevant drawing, illustrating preferred examples with the necessary details and components. The diagrams are as follows: Fig. 1: A side view of a mat lock connection of the compound mat.

Fig. 2: A section through the mat lock connection with sliding ring and plate, prior to the reversal of deformation.

Fig. 3: A side view of the mat lock with securing parts.

Fig. 4: A mat lock with a double "load and distance part." Fig. 5: A side view of mat lock with a wire bent hairpin-wise.

Fig. 6: A plan view corresponding to Fig. 5.

Fig. 7: A side view (simplified) of a sliding ring.

Fig. 8: A side view of the mat lock with a flat part.

Fig. 9: A section through the mat lock shown in Fig. 8.

Fig. 10: A side view of a mat lock with bar.

Fig. 11: A section through the mat lock shown in Fig. 10.

Fig. 12: A plan view of the mat lock shown in Fig. 8.

Fig. 13: A plan view of the mat lock shown in Fig. 10.

The compound mats 1 and 2 shown in Fig.

1 are made from intersecting longitudinal bars 3 and 4 and transversal bars 5, 6 and 7. The individual bars are welded together. The material may also consist, for example, of building mat steel, so that the costs of production of such compound mats 1 and 2 is comparatively low. The use of such inexpensive steel is made possible by the fact that the individual compound mats can be interconnected by a mat lock 8 enabling tractive forces to be adequately absorbed at an early stage and by the fact that the said mats are comparatively simple to produce.

The longitudinal bar 3, as may be seen from fig. 1, is bent over at one end 9 to form a vertical hook 10. Tbis means that the end 9 is situated at the same vertical plane as that part of the longitudinal bar 3 which passes over it. This construction for the end of the compound mat enables such compound mats to be laid in close succession to one another, thus providing an advantageous safeguard against falling rock and other types of damage and stress.

The longitudinal bar 4 of the adjacent lagging mat 1 has ends 11 which take a straight course and which are effectively connected to a ''load distance part" 1 2. A load distance part 1 2 of this kind is formed by the U shaped plate 1 5 on which is mounted a sliding ring surrounding a L-shaped plate and end 9 of the longitudinal bar 3.

One end of the U-shaped plate 1 5 is connected, preferably by welding, with the straight end 11 of the longitduinal bar 4. The various welding points are marked 16. The Ushaped plate 1 5 surrounds the end 11 of the longitudinal bar, or this latter is inserted in the said U-shaped plate 1 5. The flanks 1 7 and 1 8 of the U-shaped plate are constructed to extend up beyond the longitudinal bar 4.

As may be seen from Fig. 1, the U-shaped plate 1 5 continues with the raised flanks 1 7 and 1 8 as far as the sliding ring 25. Behind or in front of the sliding ring 25 the flanks are deformed so as to provide an immediately effective bent-up portion 19, this deformation having to be nullified as the sliding ring, if it is to be displaceable, is moved onwards. At the free end 21 of the U-shaped plate 1 5 a transversal bar 7 is mounted which provides protection against the effects of blasting action and at the same time makes it more difficult, at any rate in the end zone, for the deformation of the U-shaped plate to bereversed.This transversal bar 7 can also be situated in front of the head of the U-shaped plate 1 5. The "troughing" 20 in the plate, in the event of the complete reversal of the deformation of the U-shaped plate, remains unifrom from the welding point 1 6 as far as the free end 21. The base 22 of the U-shaped plate in the version shown in Fig. 1 thus retains a uniform thickness. The internal surfaces 23 of the U-shaped plate, dt all events in the zone of the bent-up portion 19, can be roughened or suitably coated, thus make it more difficult for the end 9 of the vertical hook 10 to be retracted.

Fig. 2 shows a front view of the zone of the mat lock 8, the deformation of the flanks 1 7 and 1 8 and the special construction of the "troughing" 20 in the plate being made clear. Hereagain the item marked 1 9 is the bent-up portion which ensures that the sliding ring 25 can only be moved onwards after appropriate deformation work.

Fig. 3 largely corresponds to Fig. 1, the base 22 of the U-shaped 1 5 in this case slanting downwards in the direction of the free end 21. The facilities the introduction of the vertical hook 10 into the U-shaped plate 1 5 of the sliding ring 25. At the same time the effect of the spacer 30 inserted between the welding-in end 11 of the longitudinal bar 4 and the rear 32 of the vertical hook 10 is intensified. This spacer 30, for instance, prevents the compound mat having the longitudinal bars 3 from being pushed back in the course of blasting operations and in the case of forward extending compound mats 1,2.It this provides an advantageous securing device, the boring 31 providing a means of connection, for example, with the transversal bars or also with the longitudinal bars, so that a spacer 30 of this kind is always available if necessary.

Figs. 1 and 3 make it clear that the last transversal bar 6 is situated practically above the mat lock 8. The last transversal bar 38 of the lagging mat connected up is likewise situated immediately above the end 11 of the longitudinal bar 4, so that as shown by Figs.

1,6 and 11 a practically continuous transversal bar securing system is created. The transversal bar 38 also serves as an additional securing means for the connection between the longitudinal bar 4 and the U-shaped plate 15.

Fig. 4 shows the version with mat ends of identical construction, i.e. with vertical hooks 10 and 40 provided at both ends. These vertical hooks 10 and 40 are operatively connected via a "double load distance part" 41 consisting of a plate 42 folded or bent Uwise and the sliding rings 25 and 24. The sliding rings 25 and 24 can be moved along the middle part 44 as far as the bent-up portions 19-46. After the vertical hooks 10 and 40 have been inserted, with tractive forces acting on the longitudinal bars 3 and 4, the sliding rings 25 and 45 are displaced, with reversal of the deformation of the Ushaped part, until the deformation of the outer most parts 47 and 48 has been reversed.

In the zone of the rear parts 32 and 32' of the vertical hooks 10 and 40 borings 49 and 50 are provided in the flanks 1 7 and 18 as a central part 44. Pins or nails, not shown, can be introduced into these borings in order to lock the mats in position in relation to one another.

The longitudinal bar 4 of the adjacent lagging mat 1 is provided, as shown in Fig. 5 with straight ends 11 operatively connected with a "load distance part" 12. The connection in this case consists of welding points 16, which are easier to apply because the ends of the load distance part 1 2 and the longitudinal bar 4 are parallel to each other.

For the connection of the two compound mats 1 and 2 the vertical hook 10 is introduced into the sliding ring 25 belonging to the load distance part 1 2 or into the aperture 26 of the said ring. If tractive forces now occur as a result of the load on the compound mats 1 and 2 the vertical hook 10 is drawn into the load distance part 1 2. In this process, as may be seen in particular from Fig. 2, the sliding ring 25 is caused to accompany the movement and pushed onto the load distance part 12, in this case taking the form of a hairpin-shaped wire 51. The wire 51 bent hairpin-wise must then be deformed or its deformation be reversed until,~owing to the high deformation resistance at the closed end 52 of the "hairpin", it cannot be compressed any further.The "hairpin end" 52 may be given various shapes, preferably those shown in Figs.

The load distance part bent hairpin-wise or the wire 51 can also be constructed as a double hook 55 at its closed hairpin end 52.

When the vertical hook 10 moves inwards its free end will enter the bent part in such a way that any upward bending is reliably prevented by the "knot" effect occurring.

The efficiency of the sliding ring 25 is guaranteed by its shape. As shown in Fig. 1, the sliding ring consists of a tubular piece 53 cut obliquely at the end facing towards the vertical hook 10 and terminating in a tongue 54. The tongue 54 advantageously counteracts any tendency of the free end of the vertical hook 10 to bend upwards.

According to Figs. 5 and 6 the hairpin shaped 51, as described, is welded to the end 11 of the longitudinal bar 3. A practically single-piece construction is likewise possible, in which case the hairpin-shaped wire 51 is bent out of the longitudinal wire 3 and 4. The free end 57 of the hairpin-shaped wire 51 is then parallel to the longitudinal bar 4, so that the sliding ring 25, which has been positioned on the longitudinal bar in advance, can be pushed on. The sliding ring 25 can also be constructed in two parts.

Fig. 4 illustrates a particular version of the sliding ring 25, in this case a deformable body twisted to form three loops. The longitudinal bar 4 and the free end 57 as well as the vertical hook 10 are introduced into the loops 59,60 and 61. The vertical hook is introduced into the middle loop 60 in such a way that when drawn in it compresses the loop openings 62 so that they become smaller, thus producing an additional clamping effect. It is important to arrange and insert the vertical hook in such a way that it acts in the direction of "twist" and not in the opposite direction, as otherwise it would open up the loops 59,60 and 61.

The longitudinal bar 3 of the adjacent lagging mat 1 has the load distance part 1 2 at its end 9 in Fig. 8 likewise. This load distance part 12, in the present case taking the form of a hairpin-shape wire 51, is connected by a weld with the straight end of the longitudinal bar 3, as shown in Figs. 8 and 1 2. As the load distance part 1 2 takes the form of a hairpin-shaped wire 51 with equal ends, both ends can be operatively connected, as shown in Fig. 12, with the ends 9 of the longitudinal bar 3.

For the connection of the two compound mats 1 and 2 the vertical hook 10 is introduced into the sliding ring 25 belonging to the load distance part 1 2 or into the rernaining opening 26 of the said ring. If tractive forces now occur as a result of the load on the compound mats 1 and 2 the vertical hook 10 is drawn into the load distance part 12. In this process the sliding ring 25, which in this case, as may be seen from Fig. 9 takes the form of a flat part 69, is displaced on the hairpin-shaped wire 51. The hairpin-shaped wire 51, as may be seen from Figs. 8 and 10, is bent out of the horizontal plane, so that when a tractive load occurs a deformation resistance is immediately created.

The defornation resistance is produced, in the first place, by thefact that the deformation of the hairpin-shaped wire 51 and of the load distance part 1 2 has to be reversed, and also as a result of the knot formation occurring at an early stage. The cause of the knot formation is the fact that the "hairpin end" 52 of the hairpin-shaped wire 51 forming a horizontal loop 56 is situated underneath the free end of the vertical hook 10 and presses the latter upwards in the course of the deformation. The sliding ring 25 and the flat part 69 are thus additionally clamped, combining with the horizontal loop 56 deform the said knot.

The hairpin-shaped wire 51, which has been bent out of the plane of the horizontal loop 56, as already mentioned, bears the flat part 25 in the bend 77. This flat part, as shown by Fig. 9, is U-shaped, the flanks 78 and 79 enclosing the corresponding wires 82 and 83 of the horizontal loop 56. The flanks are drawn forward approximately as far as the edge 84 of the wires 82 and 83, so that any tendency to bend upwards is largely counteracted but the operation of suspending the vertical hook 10 into position is not impeded.

This latter operation is carried out by the aid of the base 80 of the U-shaped flat part 69, an appropriate gap 81 for the introduction of the hook being left between the flanks 78 and 79.

It may be seen from Fig. 11 that the ends of the wire 51 bent hairpin-wise are welded to the ends 9 of the longitudinal bar 3.

Another version of the sliding ring 25 is shown in Figs. 10,11 and 13. In this case the sliding ring 25 takes the form of a simple bar 70 which in place of the front part 69 is loosely inserted into the bend of the vertical hook 10 in such a way that it automatically causes the deformation work described in relation to the hairpin-shape wire 51 and also the formation of the knot. This bar 70 is welded on at separate points, e.g. in the zone of the partial bend 73, in order to facilitate transport and also the operation of suspending the vertical hook 10 into position. The construction thus adopted, like that shown in Figs. 8 and 9, produces high deformation resistances at an early stage, which enable correspondingLy higher tractive forces to be applied.

Fig. 10 clearly shows that to enable the hairpin-shaped wire 51 to be bent out of the plane in the manner required the resulting horizontal loop 56 is bent in several places. A shorter oblique portion 75 is formed by the separate bends 71 and 72, while by the separate bends 72 and 73 the straight portion 74 is formed in which the bar 70 or the flat part 69 can advantageously positioned, the longer oblique separate portion 76 being formed behind the separate bend 73. This "stepped hook" is a double hook, as may be seen from Figs. 12 and 13, so that the deformation resistance produced well in advance is advantageously high.

In the version shown in Figs. 10, 11 and 1 3 the sliding ring 25 consist of a bar 70, in addition to which the hairpin-shaped wire 51 is formed from a longitudinal bar 3 of suitable length. The free end 57 of the hairpin-shaped wire 51 can either remain free, as shown, or be connected to the longitudinal bar 3.

The individual bends 71, 72, and 73 have been shown in Fig. 5, otherwise Figs. 1 2 and 1 3 both show plan views making the effect of the appropriately shaped mat lock additionally clear.

(1) Compound mat for the lagging of a steel roadway support system in underground mining and tunnel construction, consisting of intersecting longitudinal and transversal bars welded together at the intersection points, the longitudinal bars being bent over, at least at one end, to form vertical hooks bent out of the plane of the mat, wile at their opposite end they bear a mat lock part which when the connection is made receives the corresponding vertical hook of the adjacent mat and which is mounted on the relevant end of the longitudinal bar in such a way as to be movable along the mat by tractive forces occurring, characterized by the fact that the longitudinal bars 3,4, are in each case deformable at the end 11 opposite to the vertical hook 10 and have a sliding ring 25,69 which receives the vertical hook 10 of the adjacent compound mat 2 and which is mounted to be displaceable in the longitudinal direction while subjected to tractive force and on the forcelocked and/or formclosed principle in the direction of traction.

(2) Compound mat in accordance with Claim 1, characterized by the fact that the longitudinal bars 3,4, are straight at the end 11 opposite to the vertical hook 10 and rigidly connected to a U-shaped plate 1 5 which surrounds the relevant end 11 and which bears the sliding ring 25 mounted thereon and surrounding the plate and the inserted vertical hook and which is bent upwards at the end and beyond the sliding ring.

(3) Compound mat in accordance with Claim 2, characterized by the fact that the Ushaped plate 15, in the direction of the free end 21, is cut funnelwise to widen out at an angle of 15-30 and/or has an increasing plate thickness and/or is roughened and/or the sliding ring 25 has an opening 26 tapering conically.

(4) Compound mat in accordance with Claim 1, characterized by the fact that the longitudinal bars 3,4, are bent over at both ends 9, 11, to form vertical hooks 10,40, and the vertical hooks of adjacent compound mats 1,2, can be connected to or secured in a plate 42 which is folded U-wise and on the central part 44 of which two sliding rings 25,45, surrounding the vertical hooks 10,40, are displaceable under a tractive load, and of which the parts 44,48, situated beyond the sliding rings are bent upwards, thus having an upward bend 19,26, preventing the displacement of the sliding rings.

(5) Compound mat in accordance with Claim 1, characterized by the fact that the longitudinal bars 3,4, are constructed, at the end 11 opposite to the vertical hook 10, as a wire 51 bent hairpin-wise in its plane, the sliding ring 25 being displaceably mounted, enclosing the free end 57, on the wire bent hairpin-wise.

(6) Compound mat in accordance with Claim 1, characterized by the fact that the sliding ring 25 is a stanped metal part similar to a chain link.

(7) Compound mat in accordance with Claim 6, characterized by the fact that the sliding ring 25 is constructed as a deformable body twisted to form three loops 59,60,61, the vertical hook 10 being inserted into the middle loop 60.

(8) Compound mat in accordance with Claims 1 and 5, characterized by the fact that the wire 51 bent hairpin-wise and forming a horizontal loop 56 is bent out of the plane in the zone of the loop and that and that the sliding ring 25 is situated in the bend 77 and is constructed as a U-shaped flat part 69 which is open towards the top and which in the built-in state is enclosed by the vertical hook 10 of the adjacent lagging mat 2 and the wire 51.

(9) Compound mat in accordance with Claim 8, characterized by the fact that the sliding ring 25 is constructed as a continuous bar 70 which is adapted to the width of the lagging mat 1,2, and which is detachably mounted on the mat lock 1 2.

(10) Compound mat in accordance with Claim 8, characterized by the fact that the wire 51 bent hairpin-wise is provided, in the zone of the loop 56, with three partial bends 71,72,73, so designed that a straight section 74 is left between the second partial bend 72 and the third partial bend 73.

(11) Compound mat in accordance with Claims 8 and 10, characterized by the fact that the second slanting section 76 is longer that the first slanting section 75 by a distance at least equal to twice the thickness of the wire.

(12) Compound mat in accordance with Claims 8 and 10, characterized by the fact that the open flanks 78,79, of the U-shaped flat part 69 are constructed to project to beyond the edges 84 of the wires 82,83, of the straight section 74 and to leave a gap 81 equal to somewhat more than the thickness of the wire.

(13) Compound mat substantially as herein described with reference to Figures 1-3, Figure 4, Figures 5-7, Figures 8-11 and Figures 1 2 and 1 3 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   the appropriately shaped mat lock additionally clear.

   (1) Compound mat for the lagging of a steel roadway support system in underground mining and tunnel construction, consisting of intersecting longitudinal and transversal bars welded together at the intersection points, the longitudinal bars being bent over, at least at one end, to form vertical hooks bent out of the plane of the mat, wile at their opposite end they bear a mat lock part which when the connection is made receives the corresponding vertical hook of the adjacent mat and which is mounted on the relevant end of the longitudinal bar in such a way as to be movable along the mat by tractive forces occurring, characterized by the fact that the longitudinal bars 3,4, are in each case deformable at the end 11 opposite to the vertical hook 10 and have a sliding ring 25,69 which receives the vertical hook 10 of the adjacent compound mat 2 and which is mounted to be displaceable in the longitudinal direction while subjected to tractive force and on the forcelocked and/or formclosed principle in the direction of traction.

   (2) Compound mat in accordance with Claim 1, characterized by the fact that the longitudinal bars 3,4, are straight at the end 11 opposite to the vertical hook 10 and rigidly connected to a U-shaped plate 1 5 which surrounds the relevant end 11 and which bears the sliding ring 25 mounted thereon and surrounding the plate and the inserted vertical hook and which is bent upwards at the end and beyond the sliding ring.

   (3) Compound mat in accordance with Claim 2, characterized by the fact that the Ushaped plate 15, in the direction of the free end 21, is cut funnelwise to widen out at an angle of 15-30 and/or has an increasing plate thickness and/or is roughened and/or the sliding ring 25 has an opening 26 tapering conically.

   (4) Compound mat in accordance with Claim 1, characterized by the fact that the longitudinal bars 3,4, are bent over at both ends 9, 11, to form vertical hooks 10,40, and the vertical hooks of adjacent compound mats 1,2, can be connected to or secured in a plate 42 which is folded U-wise and on the central part 44 of which two sliding rings 25,45, surrounding the vertical hooks 10,40, are displaceable under a tractive load, and of which the parts 44,48, situated beyond the sliding rings are bent upwards, thus having an upward bend 19,26, preventing the displacement of the sliding rings.

   (5) Compound mat in accordance with Claim 1, characterized by the fact that the longitudinal bars 3,4, are constructed, at the end 11 opposite to the vertical hook 10, as a wire 51 bent hairpin-wise in its plane, the sliding ring 25 being displaceably mounted, enclosing the free end 57, on the wire bent hairpin-wise.

   (6) Compound mat in accordance with Claim 1, characterized by the fact that the sliding ring 25 is a stanped metal part similar to a chain link.

   (7) Compound mat in accordance with Claim 6, characterized by the fact that the sliding ring 25 is constructed as a deformable body twisted to form three loops 59,60,61, the vertical hook 10 being inserted into the middle loop 60.

   (8) Compound mat in accordance with Claims 1 and 5, characterized by the fact that the wire 51 bent hairpin-wise and forming a horizontal loop 56 is bent out of the plane in the zone of the loop and that and that the sliding ring 25 is situated in the bend 77 and is constructed as a U-shaped flat part 69 which is open towards the top and which in the built-in state is enclosed by the vertical hook 10 of the adjacent lagging mat 2 and the wire 51.

   (9) Compound mat in accordance with Claim 8, characterized by the fact that the sliding ring 25 is constructed as a continuous bar 70 which is adapted to the width of the lagging mat 1,2, and which is detachably mounted on the mat lock 1
2. 2.

   (10) Compound mat in accordance with Claim 8, characterized by the fact that the wire 51 bent hairpin-wise is provided, in the zone of the loop 56, with three partial bends 71,72,73, so designed that a straight section 74 is left between the second partial bend 72 and the third partial bend 73.

   (11) Compound mat in accordance with Claims 8 and 10, characterized by the fact that the second slanting section 76 is longer that the first slanting section 75 by a distance at least equal to twice the thickness of the wire.

   (12) Compound mat in accordance with Claims 8 and 10, characterized by the fact that the open flanks 78,79, of the U-shaped flat part 69 are constructed to project to beyond the edges 84 of the wires 82,83, of the straight section 74 and to leave a gap 81 equal to somewhat more than the thickness of the wire.

   (13) Compound mat substantially as herein described with reference to Figures 1-3, Figure 4, Figures 5-7, Figures 8-11 and Figures 1 2 and 1 3 of the accompanying drawings.