GB1584888A

GB1584888A - Rock drilling apparatus

Info

Publication number: GB1584888A
Application number: GB52310/77A
Authority: GB
Original assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Current assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Priority date: 1977-01-18
Filing date: 1977-12-15
Publication date: 1981-02-18
Also published as: FR2377519B3; FR2377519A1; CH633074A5

Abstract

The rock-drilling apparatus is provided with a carriage (23) which on the one side carries a displaceable drilling drive (25) for a drill rod (31) and on the other side has means (45) for positioning the apparatus at the face. The cutter-side end of the drill rod (31) is mounted in a supporting plate (27) connected to the breast-side end of the carriage, and the drill rod (31) itself runs in a tubular sound-insulating member (70) arranged between the drilling drive (25) and the supporting plate (27). At the front face of the supporting plate (27), the drill rod (31) is surrounded by an insulating body (47) closing in a soundproof manner, the front margin (50) of which, intended to bear tightly on the surface (43) of the drilling location, is provided with an elastic bearing element. The insulating body (47) contains a liquid-injection nozzle (53) on the one hand for binding the drilling dust and a discharge opening (60) on the other hand for carrying away the drillings and the working liquid. The mounting (29) of the drill rod (31) in the supporting plate (27) is provided with a sealing arrangement which prevents liquid from passing from the insulating body (47) into the sound-insulating member (70) of the drill rod (31). <IMAGE>

Description

(54) ROCK DRILLING APPARATUS (71) We, SALZGIflR MA'scHiNEN UND ANLAGEN AKTIENGESELLSCHAFT, a German company of Windmuhlenbergstrasse 20-22, D 3320 Salzgitter 51,-Federal Republic of 'Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly des cribed in andby the following statement: - The invention relates to a rock drilling apparatus.

In a -known rock drilling apparatus (Ger man - published specification 2253-842) the development of noise and dust is consider able, in particular when a drill hammer is inclined in the drilling action, in which case the superimposed percussive movement of a percussion device is applied to the rotating drilling movement.

The object of the invention is to reduce the development of noise and dust in rock drilling apparatus.

In accordance with the present invention there is provided rock drilling apparatus comprising a support carriage on which a drill rod drive is slidably mounted for longitudinal movement, a drill rod, a sup port plate mounted on the-forward end of the carriage and'having the drill rod guided therein, and a sound absorption body ex tending'forwardly of the support plate and surrounding the portion of the drill rod located immediately in front of the support .plate and sound-proofedly connected to the support plate, at least -a a forward - margin of the sound absorption body being of elastic construction. In this apparatus, on the one -han'd, the- development of dust deriving from the emission of drilling dust from the drill hole is fully avoided and, on the other hand, the essential source of noise deriving from ~the working tool operating in the drill hole is rendered innocuous. This is true whether the drill rod is driven with - pure - rotation or with rotation-and an additional percussive motion. The elastic margin of the sound absorption body compensates for eventual unevenness of-the-working face and presents an effective seal between the absorption body and the working face against rock dust and noise. The elastic margin can, for example, be formed of foam rubber.

In -accordance with a.particular -embodi- ment of the invention the connection between the support plate and the sound absorption body is flexible. Thus, :the desirable sealing between the absorption body and the work ing face can also be obtained if there exists an angle between the drill rod and the work ing : face - which is not a - right angle. Advan tageously, this flexible connection can, in accordance -with the invention, be formed as a bellows. The flexible connection can nevertheless, in accordance with the inven- tion, also comprise a hollow part-spherical element connected to the support plate and a complementary - part-spherical guide on the sound absorption' - body which cooperates with the hollow part-spherical element. The absorption body Then adapts itself auto matically to the optimum - angular working position with reference to the support plate.

The part-spherical connection can at the same time be constructed to include - a stop for this angular movement of the absorption body.

In accordance with a further embodiment of the invention at least one outlet for pres sure medium is arranged in the area of the entry of the drill rod into the sound absorp tion body. - Water, air, or also a mixture of water and air, can be considered. as pressure media. The pressure medium prevents, or at least substantially prevents, rock dust and flushing fluid which pass from the drill hole into the inside of the absorption body pass ing between the drill rod and the support plate.

In accordance with a further embodiment of the invention at least one outlet opening is provided in a wall of the sound absorption body and is connected to a sound absorbing conduit.'Rock dust and "flushing fluid are led out of the inside of the absorption-body through this outlet opening. The conduit -can terminate under the fluid level of a sump or in a soun'd-pro6fed separator. Preferably, in accordance with the invention, the outlet opening is provided at the lowest point of the inner space of the absorption body.

In accordance with an embodiment of the invention, spacer elements are provided on the forward side of the absorption body and are directed forwardly and operate in association with the elastic margin. Thus, the otherwise customary single eccentrically arranged support pin can be dispensed with.

The spacer elements can, for example, be constructed as pins arranged in a foam rubber ring forming the elastic margin.

In accordance with a further embodiment of the invention sound absorbing means encircling the drill rod are sound-proofedly connected, on the one hand, to the rear side of the support plate and, on the other hand, to the drill rod drive. Thus, the development of noise in the section between the support plate and the drill rod drive can be effectively dealt with if this development of noise becomes unreasonably high. The drill rod drive itself can also be sound-proofed in a suitable manner.

In accordance with the invention, the sound absorbing means can comprise at least one bellows. The free ends of a plurality of adjacent bellows can, in accordance with the invention, be connected as required in a sound-proofed manner with associated guide bushes for the drill rod movable along the carriage.

In accordance with another embodiment of the invention, the sound absorbing means comprise a tubular element sound-proofedly connected with the rear side of the support plate and a tubular element sound-proofedly connected with the drill rod drive, a soundproofing connection being provided between the adjacent free ends of the tubular elements. The sound-proof connection can, in accordance with the invention comprise at least one intermediate tubular element, whereby the or each intermediate tubular element is connected telescopically by its ends with the free ends of at least one of the adjacent said tubular elements. In this case, in accordance with the invention. an externally lying end of each intermediate tubular element can be fixed on an associated support slidable on a carriage of the apparatus. Furthermore, in accordance with the invention, the free end of the tubular element connected to the support plate lies externally of the adjacent tubular element and can be fixed on a support connected to the carriage.

In accordance with a further embodiment of the invention distance pieces, for example, slide rods or chains, are arranged as necessary between the drill rod drive and the support lying adjacent the drilling mechanism, on the one hand, and between two of the supports lyine adiacent to each other, on the other hand. The distance pieces ensure that the supports also take up the desired relative position with respect to each other when drilling in a sense inclined to the horizontal.

In accordance with other embodiments of the invention the tubular elements are formed of plastics material, for example polypropylene. The tubular elements can, in accordance with the invention alternatively be formed of rubber. The tubular elements can, in accordance with the invention, also all be coated on the same side with an elastic sheath, in which case, as necessary, end rings on one of the end tubular elements and on the intermediate tubular elements are in sound-proofing sliding connection with the elastic sheaths on the adjacent tubular elements. The end tubular elements and the intermediate tubular elements can, in this case, for example, consist of tubular steel and the elastic sheath can be formed of rubber or p]astics material.

In accordance with an embodiment of the invention a guide ring is arranged on an axially inner end of each elastic sheath and is in sliding contact with the adjacent tubular element. This guide ring can, for example, consist of brass or plastics material or be formed in the elastic sheath. It forms with the cooperating tubular element an effective bearing pair.

The end rings and the guide rings can, in accordance with the invention, be constructed as limit rings for the relative separation of the associated tubular elements.

In accordance with a further embodiment of the invention the elastic sheath is provided with axially spaced circumferential ribs arranged on its side spaced from the associated end tubular element or intermediate tubular element, the ribs being in sealing contact with the associated end ring. Between the individual circumferential ribs are formed annular pockets which take up foreign bodies such as rock dust and fluid which have passed to the inside of the tubular elements and eject them externally after the passage of the end ring.

In accordance with another embodiment of the invention a radial end of each circumferential rib is arranged in a radially spaced relationship from the overlying tubular element. In this way the side-by-side friction of the tubular elements is limited to the necessary amount.

In accordance with a further embodiment of the invention the tubular element connected to the drill rod drive is soundproofedly connected to a drive spindle for rotatably turning the drill rod. The tubular element on the drill rod drive therefore turns with the spindle and provides, therefore, to the operator a simple check over whether and how the drill rod is rotating in use. In the case of the departure from the desired drill rod rotation speed the operator can quickly apreciate the fact and, thereby, protect the rock drilling apparatus. In accordance with the invention the tubular element and spindle can be connected with each other releasably by way of an elastic coupling sleeve. This makes the spindle and the drill rod readily accessible in the case of need. The coupling sheath can be formed of rubber.

In accordance with a further embodiment of the invention the tubular element connected to the drill rod drive is connected to a housing of the drill rod drive. In this case, by way of the integration of the housing, a particularly efficient sound absorption is obtained.

In accordance with another embodiment of the invention the sound absorption body includes a ring rotatable about its axis and having at least one outlet opening which is connected to a sound absorbing conduit. In this embodiment, the rock drilling apparatus can be set up against the working face without reference to the actual location of the outlet opening of the absorption body. Also, in this location, the rotatable ring and the outlet opening or openings can rotate relative to the rest of the absorption body so that the outlet opening or outlet openings are directed in optimum fashion downwardly for the easy and complete emptying of the absorption body.

According to a further embodiment of the invention the ring includes an annular hollow space communicating with the outlet opening and is rotatably journalled with an open side thereof on a guide tube of the sound absorption body which includes at least one passage in communication with the hollow space.

Advantageously the guide tube is directly or indirectly secured to the support plate. This gives a particularly stiff construction and good guidance of the ring. In accordance with a further embodiment of the invention the guide ring includes a support crown at its free end adjacent the elastically constructed forward margin of the absorption body. The support crown engages with the working face and avoids an over compres sion of the forward elastic margin of the absorption body. In accordance with the invention the elastic margin can extend beyond the support crown in the rest state thereof. Then, on location of the rock drilling apparatus, it becomes more and more compressed with increase of the sealing effect until the support crown is in end-wise engagement with the working face.

In accordance with a further embodiment of the invention the elastic margin is con structed as a cuff supported in an axial sense by the remainder of the sound absorption body and expandible by a pressure medium.

The pressure medium is only conducted into the cuff when the rock drilling apparatus is in location. Then, an efficient sealing of sound absorption body against the working face is obtained by way of the cuff which lies sealingly against the working face.

In accordance with an embodiment of the invention the elastic margin is supported in an axial sense against the rotatable ring. In this way the ring is automatically fixed in its initial chosen effective rotational position until the rock drilling apparatus is once more displaced.

In accordance with an embodiment of the invention an elastic ring is arranged between the rotatable ring and the support plate. This ring allows a rotation of the ring and assures furthermore, a sealing of the ring against the sound absorption body.

If the working stroke of the rock drilling apparatus is reduced as a result of the sound absorbing measures applied to the carriage, in accordance with an embodiment of the invention, the support plate can be arranged at the forward end of an extension piece mounted on the forward end of the carriage.

By this means the overall length of the rock drilling apparatus is somewhat increased but nevertheless in practice the whole working stroke of the unsoundproofed rock drilling apparatus is available. These measures are recommended when existing rock drilling apparatus are subsequently fitted with the sound absorbing devices.

Several embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a partly schematic cross-section through a first embodiment; Fig. 2 is a part of Fig. 1 on a larger scale; Fig. 3 is a view on the section of line III- III in Fig. 1 on a larger scale Fig. 4 is a longitudinal section through the forward part of another embodiment; Fig. 5 is a longitudinal section through the forward part of a further embodiment; Fig. 6 is a longitudinal section through a part of a further embodiment; Fig. 7 is a longitudinal section through a part of another embodiment; Fig. 8 is a longitudinal section through a part of still another embodiment; Fig. 9 is a schematic longitudinal section through a further embodiment; Fig. 10 illustrates above and below the longitudinal axis two different embodiments of absorption bodies in longitudinal section and in rest condition; Fig. 11 illustrates the two embodiments of Fig. 1 in their working condition applied against a working face; and Fig. 12 a sound-proofed rock drilling apparatus in longitudinal section with an extension on the head side of the carriage.

In Fig. 1 a rock drilling apparatus 20 includes a carriage 23 on which a drilling mechanism 25 is slidable by means of a drive element, for example a chain (not illus trated). At the forward end in the sense of the direction of drilling, the carriage 23 includes a support plate 27 which guides, by way of a bush 29, a drill rod 31 provided at its forward end with a working tool 30.

The drill rod 31 is coupled, by way of a coupling sleeve 33, with an input end 37 received in a spindle 35 of the drilling mechanism 25.

The carriage 23 includes a carrier 39 of tubular construction on both sides of whose upper surface are welded guide rails 40 and 41 (Fig. 3). A support pin 45 extends forwardly of the carriage 23 against a working face 43. The carriage 23 can be three dimen sionally positionable, for example by way of a boom (not illustrated) of a travelling frame (equally not illustrated).

'In the region between the working face 43 and the support plate 27 the drill rod 31 is surrounded by an absorption body 47. The absorption body 47 is constructed essentially in a hollow frusto-conical form and on one side is fixed to the support plate 27 and on the other side is provided with a forward ring flange 49. The absorption body 47 is formed of sheet steel. A forward edge 50 of the absorption body 47 is formed as a ring 51 from foam rubber which adapts itself in sealing fashion to local unevennesses in the working face 43 and, thereby, assures a dust and sound-proof connection between the working face 43 and the absorption body 47.

An annular outlet channel housing 53 is fixed to the bush 29 and has a number of peripherally spaced outlet openings into the inner space 55 of the absorption body 47.

A pressure medium, for example pressurized water, is supplied from the outside of the absorption body 47 to the housing 53 through a tube 57, the pressure medium passing through the outlet openings in the direction of the arrows on Figure 1 and thereby preventing rock dust, and also perhaps flushing fluid, emerging from the drill hole 59 into the inner space 55 passing through the bush '29 to the rear side of the support plate 27.

It its lower region the absorption body 47 includes an exit opening 60 which is connected to a sound absorbing conduit 61 which terminates under the fluid level 63 in a sump 65. Drill spoil 66 settles out onto the floor of the sump 65.

A sound absorbent structure 70 which surroun'ds the drill rod 31 is sound-proofedly connected with a rear side of the support plate 27 and, in addition, with the drilling mechanism 25. The structure 70 includes a tubular element 73 sound-proofe'dly connected to the rear side of the support plate 27 and a tubular element 75 sound-proofedly connected with the drilling mechanism 25, 'between - which are arranged telescopic inter mediate tubular elements 76 and 77 suitably sound-proofedly sealed to each other. A free end of the tubular element 73 is fixed to a support 79 fixed to the carriage 23. The externally lying free end of the intermediate elements 76 and 77 are respectively con nected to supports 80 and 81 slidably ar ranged on the carriage 23. Distance pieces 83, 84 and 85 in the form of slide rods are slidably guided in the drilling mechanism 25 and provide a desired sliding cooperation and positioning of the supports 80 and '81 during the operation of the rock drilling apparatus 20. The tubular elements'73 and 75 and the intermediate tubular elements 76 and 77 are formed of difficultly inflammable polypropylene which is suitable''for underground use.

In Figure 2 a closure ring 90 is screwed into the inner end of the intermediate tubular element 77 and carries on its inner periphery a metallic guide ring 93 for the drill rod 31 and on its outer periphery a guide ring 95 formed of plastics material which is in slid ing contact with the inner wall of the intermediate tubular element 76. On an outer face of the intermediate tubular element 76 there is located a ring seal 97 which has another face in sound-absorbing sealing connection with the outer peripheral surface of the intermediate tubular element 77. The ring seal 97 is held in a position by means of a multi-part shell 100 secured together by screws 99.

In Figure 3 there is shown how the support 80 grips over the guide rails 40 and 41 of the carriage 23 by way of a shoe 103.

In the embodiment of Figure 4 a'hollow spherical element 110 is fixed to a forward end of the bush 29 and guides the absorption body 47 by way of a complementary spherical guide 113 cooperating with the hollow spherical element 110. In this way a flexible connection is created between the absorption body 47 and the support plate 27. The annular outlet channel housing '53 is, in this case, supplied with a pressure medium by way of a connecting channel 115 in the bush 29.

Figure 5 shows a modified embddiment of the absorption body 47 in so far as pin shaped spacing elements 117 are fixed to the flange 49 and 'arse directed forwardly thereof. Each spacing element is arranged in a through hole 118 in the elastic ring 51.

As the upper half of ' Figure 5 shows the ring 51, in its rest condition, extends forwardly over the points of the spacing elements 1I7. On the other hand as shown in the lower half of'Figure'5, when the absorption body 47 is applied against the working face 43, the elastic ring 51 is compressed until the spacing elements contact the working face 43. 'Thus, a complete crushing 6f the elastic ring 51 is-avoide'd and an isolated support pin corresponding to the support pin 45 in Figures 1 and 4 becomes unnecessary.

In accordance with the embodiment of Figure 6 the tubular element 75 includes a steel tube 120 which is coated on its outside with an elastic sheath 121, for example a rubber sheath. A transition ring 123 is welded to one end of the steel tube 120 and is secured with screws 125 to a housing 127 of the drilling mechanism 25. At its free end the steel tube carries a guide ring 130 secured by a retaining ring 129 and in sliding contact with the inner surface of a steel tube 131 of the intermediate tubular element 77. The guide ring 130 lies against one end face of the elastic sheath 121 and extends radially outwardly of this elastic sheath 121.

The intermediate tubular element 77 also carries, externally, an elastic sheath 133 and a closure ring 135 at one of its ends. An end ring 137 is located in the closure ring 135 and is held against an end face of the steel tube 131 and in position by a retaining ring 139. The end ring 137 has its radially inner face in sound proofed sliding contact with the elastic sheath 121. Further tubular elements not illustrated in Figure 6 are constructed in a similar fashion as the tubular element 75 and the intermediate tubular element 77.

The exemplary embodiment according to Figure 7 is similar to that of Figure 6. Between the intermediate tubular elements 76 and 77 there is arranged a further intermediate tubular element 140. The tubular element 73 and the intermediate tubular elements 76 and 140 have respectively a steel tube 143, 144 and 145 which, as with the steel tubes 120 and 131 in the case of Figure 7, are externally sheathed with elastic sheaths 150 to 154. The elastic sheaths 151 to 154 are provided externally with axially spaced circumferential ribs 157 which are radially spaced from the inner wall of the adjacent steel tubes 143, 144, 145 and 131.

In each case the circumferential ribs 157 pass into sealing contact with the associated end ring 137 by way of an entry curve 159.

The end rings 137 are respectively secured through a face ring 160 which is fixed with screws 161 to a respective closure ring 135.

In Figure 8 the tubular element 75 is not coupled to the housing 127 of the drilling mechanism 25 but rather with its spindle 35.

This is obtained by way of an elastic, for example rubber, coupling sleeve 165 which is secured to the steel tube 120 by means of a spring band 167 and a screw 168 and secured to the spindle 35 by means of a spring band 169 and a screw 170. Upon rotation of the spindle 35 through the drilling mechanism 25 the tubular element 75 is therefore rotatably driven with it.

In Figure 9 the flexible connection between the absorption body 47 set against an inclined working face 43 and the support plate 27 is formed as a bellows 180. Also, the sound absorbing structure 70 is constructed, in Figure 9, with bellows 183 and 184 whose adjacent ends are sound-proofedly connected to a guide bush 187 for the drill rod 31 which is movable along the carriage 23. The other end of the bellows 83 is soundproofedly connected to the rear side of the support plate 27 and the other end of the bellows 184 is similarly connected with the housing 127 of the drilling mechanism 25.

A distance piece 190 in the form of a slide rod between the guide bush 187 and the drilling mechanism 25 ensures the correct positioning of the guide bush 187 and avoids an over extension of the bellows 183 and 184.

In the embodiment of Fig. 10 a partially illustrated rock drilling apparatus 201 includes a carriage 203, a support plate 204 forwardly on the carriage 203 and having therein a fixed bush 205 for a drill rod 208 carrying a working tool 207 at the forward end thereof. The drill rod 208 is provided with an axial bore 209 through which flushing fluid is passed to the working tool 207 in the direction of the arrow.

On the rear side of the support plate 204 there is flanged a tube support 211 on which a tubular element of sound absorbing material, in this case of rubber, is securely slid. The tubular element 212 and additional, not illustrated, similar tubular elements, which are telescopically guided in each other, surround the whole drill rod 208 and provide an effective sound absorption.

A spray plate 214 is screwed onto the forward side of the support plate 204. A pressure medium, for example pressurised water, is led to the spray plate 214 through a conduit 215 and passes through a connection channel 216 into an annular channel 217 of a nozzle insert 218 of te spray plate 214. The pressure medium passes out of the annular channel 217 through annular nozzle outlets 220 in the region in which the drill rod 208 enters through the nozzle insert 218 into a guide tube 221 of an absorption body 223 secured to the forward portion of the spray plate 214. The pressure medium emerging from the nozzle openings 220 prevents drill spoil and, if applicable, flushing fluid passing out of the drill hole 225 (Fig.

11) into the inner part of the guide tube 221 and through the nozzle insert 218 and the bush 205 through to the rear side of the support plate 204.

The guide tube 221 includes forwardly thereof a support crown 226 with which there is created a closed form contact with a working surface 227 which: is concentric to the drill rod 208. Approximately in its longitudinally central portion the guide tube 221 includes a passage 229 which communi cates its inner space with an annular hollow space 230 of a ring 231. The ring 231 is rotatably journalled on and with its open side to the guide tube 221 and includes an outlet opening 233 which is communicated to a sound absorbing conduit 235 by a connection support 234, the conduit terminating below the fluid level of a sump (not illustrated). The ring 231 is provided externally with a sound absorbing sheath 236.

An elastic ring 238 is located between the rotatable ring 231 and the spray plate 214 and serves both as a sound absorbent and also as a sealing element for flushing medium and pressure medium coming out of the nozzle openings 220.

The absorption body 223 includes a forward elastic edge 240. Above the longitudinal central axis of Figs. 10 and 11 there is shown, as a first embodiment of this elastic edge 240, a tubular cuff 241 applied in a radial sense around the guide tube 221 and, in an axial sense, against a side wall of the rotatable ring 231. The inner space of the cuff 241 is connected to a conduit 242 through which pressure medium can be fed into the cuff 241. This occurs if the support crown of Fig. 11 is laid against the working surface 227. The cuff 241 is then in a position to bridge, in a sealing manner, large unevennesses in the working surface 227 so that, around the drill rod 208, a satisfactory seal against sound and fluid between the working surface 227 and the absorption body 223 is created. As soon as the drilling process is ended, the pressure medium is released from the cuff 241 through the conduit 242. Thus, the cuff 241 contracts once again to the size illustrated in Fig. 10.

Below the longitudinal central axis of Figs.

10 and 11 there is shown another embodiment of the elastic edge 240 in the form of a rubber ring 244 extending, in the rest condition shown in Fig. 10, over the forward end of the support crown 226. The rubber ring 244 is held on the guide tube 221 by a band 245. If the rock drilling apparatus 201 is led into contact with the working surface 227, the rubber ring 244 lies against the working surface 227 and is further and further compressed until a satisfactory contact of the support crown 226 with the working surface 227 is obtained and it then takes the form shown in Figure 11. In this position a good seal against sound and fluid between the guide tube 226 an

Claims

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

cates its inner space with an annular hollow space 230 of a ring 231. The ring 231 is rotatably journalled on and with its open side to the guide tube 221 and includes an outlet opening 233 which is communicated to a sound absorbing conduit 235 by a connection support 234, the conduit terminating below the fluid level of a sump (not illustrated). The ring 231 is provided externally with a sound absorbing sheath 236.

An elastic ring 238 is located between the rotatable ring 231 and the spray plate 214 and serves both as a sound absorbent and also as a sealing element for flushing medium and pressure medium coming out of the nozzle openings 220.

The absorption body 223 includes a forward elastic edge 240. Above the longitudinal central axis of Figs. 10 and 11 there is shown, as a first embodiment of this elastic edge 240, a tubular cuff 241 applied in a radial sense around the guide tube 221 and, in an axial sense, against a side wall of the rotatable ring 231. The inner space of the cuff 241 is connected to a conduit 242 through which pressure medium can be fed into the cuff 241. This occurs if the support crown of Fig. 11 is laid against the working surface 227. The cuff 241 is then in a position to bridge, in a sealing manner, large unevennesses in the working surface 227 so that, around the drill rod 208, a satisfactory seal against sound and fluid between the working surface 227 and the absorption body 223 is created. As soon as the drilling process is ended, the pressure medium is released from the cuff 241 through the conduit 242. Thus, the cuff 241 contracts once again to the size illustrated in Fig. 10.

Below the longitudinal central axis of Figs.

10 and 11 there is shown another embodiment of the elastic edge 240 in the form of a rubber ring 244 extending, in the rest condition shown in Fig. 10, over the forward end of the support crown 226. The rubber ring 244 is held on the guide tube 221 by a band 245. If the rock drilling apparatus 201 is led into contact with the working surface 227, the rubber ring 244 lies against the working surface 227 and is further and further compressed until a satisfactory contact of the support crown 226 with the working surface 227 is obtained and it then takes the form shown in Figure 11. In this position a good seal against sound and fluid between the guide tube 226 and the rotatable ring 231 is obtained.

In Fig. 12 the same parts as shown in Figs. 10 and 11 have the same reference numerals. An extension piece 247 is, in this case, mounted on the forward end of the carriage 203 by screws 246 and it carries at its forward end the support plate 204. The axial length of the extension piece 247 corresponds approximately to the length of the tubular element 212. Further tubular element 212. Further tubular elements 249, 250 and 251 are telescopically arranged around the tubular element 212 towards the rear and sound-proofedly enclose the drill rod 208 up to a drill mechanism 255 slidable on the carriage 203. The tubular elements 212, 249, 250 and 251 are longitudinally slidably supported on the carriage 203 as required by way of supports 256, 257 and 258.

WHAT WE CLAIM IS: 1. Rock drilling apparatus comprising a support carriage on which a drill rod drive is slidably mounted for longitudinal movement, a drill rod, a support plate mounted on the forward end of the carriage and having the drill rod guided therein, and a sound absorption body extending forwardly of the support plate and surrounding the portion of the drill rod located immediately in front of the support plate and sound proofedly connected to the support plate, at least a forward margin of the sound absorption body being of elastic construction.
2. Rock drilling apparatus according to claim 1, wherein the connection between the support plate and the sound absorption body is flexible.
3. Rock drilling apparatus according to claim 2, wherein the flexible connection comprises a bellows.
4. Rock drilling apparatus according to claim 2, wherein the flexible connection includes a hollow part-spherical element connected to the support plate and a partspherical guide on the sound absorption body which is complementary with and cooperates with the hollow part-spherical element.
5. Rock drilling apparatus according to any one of claims 1 to 4, wherein at least one outlet for a pressure medium is arranged in the region of the entry of the drill rod into the sound absorption body.
6. Rock drilling apparatus according to any one of claims 1 to 5, wherein an outlet opening is provided in a wall of the sound absorption body and is connected to a sound absorbing conduit.
7. Rock drilling apparatus according to claim 6, wherein the outlet opening is provided at the lowest point of the inner space of the sound absorption body.
8. Rock drilling apparatus according to any one of claims 1 to 7, wherein spacer elements, which operate in association with the elastic forward margin of the sound absorption body, are provided forwardly of the absorption body and are directed forwardly.
9. Rock drilling apparatus according to any one of claims 1 to 8, wherein sound absorbing means encircling the drill rod are sound proofedly connected at one end to the

rear side of the support plate and at the other end to the drill rod drive.
10. Rock drilling apparatus according to claim 9, wherein the sound absorbing means includes at least one bellows.
11. Rock drilling apparatus according to claim 10, wherein the sound absorbing means comprises a plurality of bellows and wherein the adjacent free ends of adjacent bellows are respectively sound-proofedly connected to a guide bush for the drill rod longitudinally movably mounted on the carriage.
12. Rock drilling apparatus according to claim 9, wherein the sound absorbing means include a tubular element sound-proofedly connected to the rear side of the support plate and a tubular element sound-proofedly connected with the drilling mechanism, and wherein a sound-proof connection is provided between the adjacent free ends of the tubular elements.
13. Rock drilling apparatus according to claim 12, wherein the sound-proof connection comprises at least one intermediate tubular element and wherein the or each intermediate tubular element is telescopically connected at its ends with the free end of at least one of adjacent said tubular elements.
14. Rock drilling apparatus according to claim 13, wherein an externally lying end of each intermediate tubular element is fixed to an associated support slidable on the carriage.
15. Rock drilling apparatus according to claim 13 or 14, wherein the free end of the tubular element secured to the support plate lies externally of the adjacent tubular element and is fixed to a support connected to the carriage of the apparatus.
16. Rock drilling apparatus according to claim 14 or 15, wherein distance pieces, for example slide rods or chains, are arranged respectively between the drill rod drive and the support lying closest to the drilling mechanism on the one hand and between two adjacent ones of the supports on the other hand.
17. Rock drilling apparatus according to any one of claims 13 to 16 wherein the tubular elements are formed of plastics material, for example, polypropylene.
18. Rock drilling apparatus according to one of claims 13 to 16, wherein the tubular elements are formed of rubber.
19. Rock drilling apparatus according to any one of claims 13 to 16, wherein the tubular elements are all coated on the same side thereof with an elastic sleeve and end rings on one of the end tubular elements and on the intermediate tubular elements are in sliding sound-proof connection with the elastic sleeve of the adjacent tubular elements.
20. Rock drilling apparatus according to claim 19, wherein a guide ring is arranged at an axially inner end of each elastic sheath and is in sliding contact with the adjacent tubular element.
21. Rock drilling apparatus according to claim 20, wherein the end rings and the guide rings are constructed as limit rings for the relative telescopic separation of the associated tubular elements.
22. Rock drilling apparatus according to any one of claims 19 to 21, wherein the elastic sheaths are each provided on their radial surfaces spaced from the associated tubular elements with axially spaced circumferential ribs which are engageable in sealing contact with the associated end ring.
23. Rock drilling apparatus according to claim 22, wherein a radial end of each circumferential rib is arranged with radial spacing from the surface of the oppositely disposed tubular element.
24. Rock drilling apparatus according to any one of claims 12 to 23, wherein the tubular element connected to the drill rod drive is sound-proofedly connected to the drive spindle.
25. Rock drilling apparatus according to claim 24, wherein the tubular element and spindle are releasably connected to each other by way of an elastic coupling sheath.
26. Rock drilling apparatus according to any one of claims 12 to 23, wherein the tubular element connected to the drill rod drive is connected to a housing of the drill rod drive.
27. Rock drilling apparatus according to claim 1, wherein the sound absorption body includes a ring rotatable about its axis and having at least one outlet opening which is connected to a sound absorbing conduit.
28. Rock drilling apparatus according to claim 27, wherein the ring includes an annular hollow space communicating with the outlet opening and is rotatably journalled with an open side thereof on a guide tube of the sound absorption body which includes at least one passage in communication with the hollow space.
29. Rock drilling apparatus according to claim 28, wherein the guide tube is fixedly connected to the support plate.
30. Rock drilling apparatus according to claim 28 or 29, wherein the guide tube includes a support crown adjacent its free end and the elastically constructed forward margin of the sound absorption body.
31. Rock drilling apparatus according to claim 30, wherein said forward margin, in the rest state thereof, extends beyond the support crown.
32. Rock drilling apparatus according to claim 30, wherein said forward margin is constructed as a tubular cuff which is expandible by way of a pressure medium and is supported in an axial sense by the remainder of the absorption body.
33. Rock drilling apparatus according to any one of claims 27 to 32, wherein said forward margin of the absorption body is supported in an axial sense by the rotatable ring.
34. Rock drilling apparatus according to any one of claims 27 to 33, wherein an elastic ring is arranged between the rotatable ring and the support plate.
35. Rock drilling apparatus according to any preceding claim, wherein the support plate is arranged at the forward end of an extension piece mounted on the forward end of the carriage.
36. Rock drilling apparatus as herein described with reference to Figures 1 to 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figures 10 and 11 or Figure 12 of the accompanying drawings.