EP0004946A1 - Bore hole hammer, especially down-the-hole hammer - Google Patents

Abstract

A hammer drill, in particular deep hole hammer drill (10), is provided with a connection (16) for a compressed air source and a three-part control housing (30, 32, 34) which has a valve and deflection system (38, 40; 44, 46, 50, 52 ) and sits in a jacket body (22) which is attached to an outer tube (12). A central sliding tube (60) is positively connected to the control housing and guides a main piston (70) and an intermediate piston (80), which can be moved back and forth on a drill bit (94). A check valve (59, 61) can be arranged at the lower end of the sliding tube (60). An insert (62) is mounted in the sliding tube (60), which forms a number of channels (67, 68) through partitions (64), which open into radial openings (69, 71, 73, 74) which extend from the sliding tube (60 ) from different flow connections.

Description

The present invention relates to a pneumatically driven hammer drill, in particular a deep hole hammer, with an outer tube and through hole in an upper cap for connection to a compressed air source and optionally to a drill pipe, with the control housing, control body and cylindrical slide tube supported on the cap, along which a pierced percussion piston is movable up and down in the outer tube, and with a radially divided lower retaining cap of disharmonious polygonal inner profile, in which a polygonal shaft, likewise pierced, of a drill bit provided with flushing bores is movably supported up and down.

Such hammer drills are known from DE-PS 26 09 376. DE-PS 23 62 724 and GB-PS 1 419 981 describe deep hole drilling hammers in a similar configuration, but without polygonal profile elements, in which, however, the guide tube itself is movably mounted up and down and protrudes into the head of the drill bit, which has considerable disadvantages. in the Rough drilling operations cause the lower hammer parts to wear out relatively quickly, which can lead to canting of the drill bit with risk of breakage for the end of the guide tube. It is also possible that the serration of the drill bit shaft provided for rotary driving is deformed or jammed, at least when an eccentric position of the sliding tube causes a force transmission to the outer tube or from there. It is also unfavorable that in the case of sudden holes or caverns in the rock, the actual drilling lack ceases because the drill bit sinks, which is then uselessly processed by the percussion piston in a kind of cold forging process, with the outer parts such as the retaining ring, stop shoulders, etc. being damaged.

It is an important object of the invention to simplify the construction of a hammer drill of the type mentioned at the outset for the purpose of economical production and easier maintenance, and at the same time to improve its drilling performance, with an undisturbed hammer operation being ensured especially when the drill bit is sagging or struck by loose rock.

In a hammer drill of the type mentioned, it is provided according to the invention that an intermediate piston is arranged between the percussion piston and the drill bit head and is guided at least in part on the sliding tube, which is positively connected to the control housing, in particular via buffer rings. Thanks to this training, the hammer either runs in intermittent operation, the impact can be switched on and off, or overall continuously. The impact of the impact piston is transferred to the drill bit head by the intermediate piston, which has an important buffer function. It contributes significantly to the air flow and causes a vibration effect with continuous air strikes even when the percussion piston is intercepted by an air cushion with a deeply immersed intermediate piston or sagging drill bit and no longer strikes the intermediate piston.

Cold forging deformation in idle mode is therefore excluded here as well as on the drill bit head. Due to the good guidance of the intermediate piston, in particular in a buffer sleeve that is inserted into the outer tube, a safe function with good control of the hammer operation is maintained for a long time, in contrast to an embodiment according to US Pat. No. 2,661,928, where an upper and a lower piston can easily tilt and there is no buffer effect.

Developments of the invention according to claims 2 to 6 offer great advantages in terms of production technology and ensure additional securing of the form-fitting connection between the guide tube and the control housing. Compared to the older designs mentioned at the beginning, there are great savings in production and assembly. As a result of the very simple structure, the control is further improved, since the supply and exhaust air are routed in large cross sections, particularly in the central control section, with little deflection.

The casing body provided according to claims 6 and 7 and its outer groove profile allow the hammer to be opened more easily than before in the event of malfunctions or chisel changes. Conventional rotary hammers can sometimes not be released at all, while others are severely weakened in the casing and have predetermined breaking points. In many cases, attaching the necessarily heavy tool creates a high risk of accidents, since it slips and falls easily with conventional designs. According to the invention, however, a closed tool can be used, which is temporarily fixed by one or more bolts on the circumference of the hammer, in particular the casing body.

The embodiment according to claim 8 creates a multi-channel inner tube control system that works extremely reliably with a simple and stable structure. Favorable is by name a four-channel system with intersecting pairs of opposing exhaust and return stroke channels; this ensures that the air flows out very evenly and the piston cannot jam.

The features of claims 9 and 10 result in a particularly good coordination between the buffering space and the lower opening to the return stroke channel. The dimensioning can be made in this way. be that the greatest performance is achieved with a half-sagging drill bit, while with increasing chisel path there is a gradual decrease in output until pure buffer operation, which prevents the chisel head and the stop parts from being smashed. The buffer sleeve is provided with adapted ventilation grooves in order to transfer the impact energy to the maximum, whereby the buffer effect starts somewhat delayed, but the piston is not caught too early or too strongly.

There is also an advantageous simplification in the measures of claim 11, since, in contrast to the prior art, this means that only a minimal machining of the guide tube is necessary. Several, distributed over the length of the guide tube for each channel provides the embodiment according to claim 12, wherein the upper shut-off hole, which has a greater width than the lower shut-off hole leading into the return stroke channel, despite the intermediate piston located in the lower end position, an air ejection takes place can. Therefore, the hammer can continue to run while the buffer effect persists, or the hammer is turned off and the air flows out.

The air, which continues to flow intermittently or continuously, causes a good flushing on or around the drill bit, even while the percussion piston no longer comes into metallic contact with the intermediate piston due to the air spring formed. The measure of claim 13 contributes to this, since the enlarged head of the intermediate piston exactly limits the buffer volume when entering an upper annular space of the buffer sleeve.

The radial outlets of the intermediate piston at its lower end communicate with air spaces in and around the drill bit. Its design according to claims 14 and 15 ensures perfect air flow in any axial position of the drill bit. The disharmonious polygonal profile is not only cheaper for rotating entrainment than any involute toothing, but also enables axial air ducts to be conveniently accommodated without disadvantageous material weakening or a reduction in cross-section.

By using a check valve located below, the inside of the hammer is reliably protected and at the same time the air flow is further improved; a "standing" air cushion, which would quickly overheat due to high-frequency adiabatic compression, cannot form. According to the prior art, a check valve - if at all - was usually only arranged in the upper part of the hammer above the control, so that when the hammer was turned off, its lower part was fully exposed to the penetration of cuttings, dust, water, etc. In addition, a threaded plug provided according to claim 17 on the head of the lower control housing part can, if necessary, be designed as a nozzle which, with a predetermined cross section, allows an additional air passage if this is desired. The control can be changed as required by replacing the threaded plug. It can be omitted if, for use as a water hammer, the entire control housing is penetrated by a central tube or bore through which water can be introduced.

• Fig. 1a + 1b eine Gesamt-Längsschnittansicht eines erfindungsgemäßen Bohrhammers, wobei der untere Teil von Fig. 1b der Schnittführung entsprechend der Linie Ib-Ib von Fig. 4 entspricht,
• Fig. 2 einen Längsschnitt durch einen unteren Steuergehäuseteil mit Gleitrohr,
• Fig. 3 einen Querschnitt entsprechend der Linie III-III in Fig. 2 unter Weglassung des dort gezeichneten Sicherungsstiftes,
• Fig. 4 einen Querschnitt entsprechend der Linie IV-IV in Fig. 1b,
• Fig. 5 einen vergrößerten Längsschnitt durch einen Zwischenkolben und
• Fig. 6 eine Stirnansicht des Zwischenkolbens von Fig. 5.

Further features, details and advantages of the invention result from the following description of exemplary embodiments with reference to the drawing. In it show:

• 1a + 1b is an overall longitudinal sectional view of a hammer drill according to the invention, the lower part of Fig. 1b corresponding to the cut according to the line Ib-Ib of Fig. 4,
• 2 shows a longitudinal section through a lower control housing part with a sliding tube,
• 3 shows a cross section along the line III-III in FIG. 2, omitting the locking pin drawn there,
• 4 shows a cross section along the line IV-IV in FIG. 1b,
• Fig. 5 is an enlarged longitudinal section through an intermediate piston and
• 6 is an end view of the intermediate piston of FIG. 5.

At Fig. 1a, Fig. 1b is to be considered below. The hammer drill 10 shown has an outer tube 12 and an upper cap 14 which is provided with a threaded connection 16 and wrench flats 18 and has a through hole 2C. Depending on the existing drive device, a suitable connection can be attached to the rotary hammer 10 by simply changing the cap 14. The cap 14 screws with a jacket body 22, which in turn is screwed to the outer tube 12 and comes into contact with the collar or shoulder 28 thereof. For these screws required for assembly and disassembly, a grooved profile 24 is provided on the outside of the jacket body 22, via which a closed key (not shown) can be pushed and fixed in the circumferential and axial directions by at least one socket pin. The hammer drill 10 can also have a corresponding groove profile at other points, for example at its lower end.

The upper part 30 of a three-part control housing is supported on the cap 14 in the jacket body 22 via buffer rings 26 and 27, which would consist of elastomers such as polyurethane. The upper part 30 is provided with a number of oblique channels 36 distributed over the circumference. On its underside it has a valve seat 38 for a control body 40, which is movable back and forth in the axial direction between a valve support 42 of the control housing middle part 32 and the valve seat 38 of the upper part 30 and is guided centrally in the middle part 32. The latter is distributed over the circumference with a number Inclined channels 44 and following the control body 40 with a chamber 48. In the central part of the control housing 32, outer or side channels 46 lead to the head of the lower part 34, at least one of which opens into bores 52 which are incorporated in the head of the lower part 34 of the control housing.

An axial section of the bores 52 is closed with a threaded plug 54 which, if necessary, can be replaced by a nozzle of a suitable diameter. A number of passages 50 distributed over the circumference create a flow connection between the chamber 48 and an annular space 55 in the interior of the outer tube 12.

An insert 62 is integral with the control housing lower part 34 and has a sliding tube 60 connected to it integrally. To secure this attachment, a screw connection (not shown) may be present. Optionally or additionally, lower part 34 or insert 62 and sliding tube 60 are penetrated by a transverse pin 58 with a precise fit just below a collar 35. This is dimensioned in length so that it fits into the inside width of a collar 56 of the casing body 22 and is thereby secured against movements in the direction of its axis. The insert 62 has, as can be seen from FIGS. 2 and 3, partitions 64 which connect to one another in a star shape in cross-section and bear with surfaces 66 on the inside of the sliding tube 60. The length of the insert 62 can match that of the sliding tube 60 or, as drawn in FIGS. 1b and 2, may be somewhat shorter.

At the lower end of the sliding tube 60, as shown in FIG. 2, it can have an inwardly projecting collar 61 which is chamfered and serves as a valve seat for the valve body 59 of a check valve. The body 59 is slidably supported on a pin 63 which extends the insert 62 coaxially and is supported against the end thereof, to which nuts 63a can be screwed in a suitable manner, by a compression spring 65, which is partially immersed in the body 59.

In the exemplary embodiment, the sliding tube 60 each has a preferably elongated outlet 69 (shown in broken lines in FIG. 1b) for two exhaust channels 67, which are formed by the four web walls 64 together with two return stroke channels 68. The arrangement is preferably such that the diametrically opposite exhaust ducts 67 have a larger cross-section than the crossed return stroke ducts 68; the ratio of the cross sections can be 3: 2, for example.

At the lower end of the sliding tube 60, it has a lateral ventilation opening 74 for establishing a flow connection between each return stroke channel 68 and a compression space 76, which is present between the outer tube 12 and the sliding tube 60 below a percussion piston 70. Above the ventilation openings 74, an upper idle or shut-off hole 71 leads to the exhaust ducts 67, while below the openings 74 a smaller lower shut-off hole 73 opens into a chamber 115, which is located in the sliding tube 60 at the lower end of the insert 62.

The percussion piston 70 is guided in the outer tube 12 and provided with circumferential grooves 72. Its lower end faces axially opposite the head 82 of an intermediate piston 80. Percussion piston 70 and intermediate piston 80 slide along tube 60. The intermediate piston 80 is partially guided on the sliding tube 60 and in a buffer sleeve 78 which is inserted into the outer tube 12 from below and has adapted longitudinal grooves 79. At the lower end of its cylindrical body, the intermediate piston 80 has two or more radial outlets 84; In the exemplary embodiment according to FIGS. 1 b, 5 and 6, there are three such radial outlets 84 which establish the flow connection to a lower annular space 88. An upper annular space 86 connects to the compression space 76 in the buffer sleeve 78.

A retaining cap 90, which is formed in two parts, held together by pins 92 and into the outside, serves to fasten both the buffer sleeve 78 and a drill bit 94 tube 12 is screwed in from below. Inside, the holding cap 90 has a disharmonious polygon profile, in particular of the PC4 type, as described in DE-PS 26 09 376. The drill bit 94 has a head 106 with an enlarged diameter and a shank 96 which - as can be seen in FIG. 4 - has a precisely adapted polygonal profile with slightly curved surfaces and strongly rounded edges. In the latter, there are axial grooves 98, which lead via an annular gap 100 to recesses 112, which are also in constant flow communication with the space outside the hammer drill 10 or the drill bit 94 when the latter is in contact with a collar 110 at the lower end of the holding cap 90 . The chisel head 106 can move down to a stop 108 at which the polygonal inner profile of the holding cap 90 ends at the top. A through hole 102 of the drill bit 94 leads to the drill bit 104 and branches therein, as indicated by dashed lines in FIG. 1b.

It is essential for the hammer drill 10 according to the invention that it enables a robust construction with high space utilization with simplified and improved control. Practical designs with outer tube diameters from 80 mm to 135 mm have achieved surprising drilling progress in operation with a pressure of 13 bar, even in unfavorable rock conditions. This contributes to the fact that the intermediate piston 80 guided in the buffer sleeve 78 is constantly on the drill bit head 106 and thus either releases the return air bore 74 or closes it (partially or completely). If the head 82 of the intermediate piston 80 completely enters the upper annular space 86, the compression space 76 located above it prevents the impact piston 70 from striking by its air cushion. Rather, the latter resiliently springs upwards, as a result of which - if the other requirements are met - drill bits 94 and Intermediate piston 80 can also retract. The strokes of the percussion piston 70 which occur continuously with the hammer 10 running continuously produce sequences of air blasts which, in addition to cause high gas accelerations due to a vibration effect and thereby significantly support the drilling work or enable intermittent operation with correspondingly dimensioned parking bores 71, 73.

The lower annular space 88 serves primarily for air distribution to the ventilation channels 98, 100, 112. This complete ventilation allows the drill bit head 106 to move down to the stop shoulder 108 of the holding cap 90. Between this and the drill bit there is the practically wear-free polygon guide, which allows the transmission of torques in a wide range even with large axial forces. The conventionally given risk of breakage for the lower end of the sliding tube is eliminated according to the invention in a simple and effective manner. The sliding tube 60 is optimally protected by its connection to the insert 62 or the lower control housing part 34, especially since the drill bit 94 never comes into contact with the sliding tube 60.

There are further advantages over the known embodiments. Thus, the upper parts 30, 32 of the control housing are greatly simplified, which not only greatly simplifies manufacture and assembly, but also increases functional reliability. The available cross sections are used optimally. Furthermore, effective assembly and disassembly aids are provided in the form of the key grooves 24 and key surfaces 18, which considerably shorten the set-up and downtimes compared to conventional rotary hammers. The clear structure ultimately helps to make maintenance and repair work easier and thereby accelerate it without the mechanical and wear resistance being impaired in any way. While the mode of operation largely corresponds to that of the deep hole hammer according to DE-FB 26 09 376, the versatility of use and the cost-effectiveness of use is considerably increased.

Through a central tube 113 (shown in dashed lines in FIGS. 1a and 1b), which passes through the control body upper part 30 and middle part 32 and projects into the lower part 34, where in the insert 62 a central bore 114 (indicated in FIG. 3) with dashed lines) water can be introduced and the device can also be used as a water hammer. It can be seen that no additional effort is required for this; the threaded plug 54 can be omitted or modified accordingly.

Numerous modifications and simplifications fall within the scope of the invention. All of the advantages and advantages of the invention, including constructive details, spatial arrangements and method steps, which emerge from the claims, the description and the drawing, can be essential to the invention both individually and in a wide variety of combinations.

Living PA 281

10 hammer drills

12 outer tube

14 top cap

16 threaded connection

18 key faces

20 through hole

22 coat (body)

24 groove profile

26.27 buffer rings

28 fret

30 upper part 32 control housing middle part 34 lower part 35 collar

36 inclined channels

38 valve seat

40 control bodies

42 valve supports

44 inclined channels

46 side channels

48 chamber

50 passages

52 exhaust hole (s)

54 threaded plugs

55 annulus

56 collar

58 pen

59 valve body

60 sliding tube

61 final covenant

62 use

63 cones

64 partition (s)

65 valve spring

66 contact surfaces

67 exhaust channels

68 return stroke channels

69 exhaust opening (s)

70 percussion pistons

71 upper parking hole 72 circumferential grooves

73 lower parking hole 74 ventilation opening

76 compression space

78 buffer sleeve

79 longitudinal grooves

80 intermediate pistons

82 head

84 outlets

86 upper annulus

88 lower annulus

90 holding cap

92 pinning

94 drill bits

96 polygon shaft

98 grooves

100 annulus

102 through hole

104 crown

106 chisel head

108 stop

110 volume

112 recess (s)

113 central tube 114 central bore

115 chamber

Claims (18)

1. Pneumatically driven hammer drill, in particular deep hole hammer, with an outer tube and through hole in an upper cap for connection to a compressed air source and, if appropriate, to a drill pipe, with the control housing, control body and cylindrical sliding tube supported on the cap, along which a pierced percussion piston in the outer tube and is movable, and with a radially divided lower retaining cap of disharmonious polygonal inner profile, in which a likewise pierced polygonal shaft of a drill bit provided with flushing bores is movably supported up and down, characterized in that between the percussion piston (70) and the drill bit head (106) an intermediate piston (80) is arranged and is guided at least in part on the sliding tube (60) which is positively connected to the control housing (34), in particular via buffer rings (26, 27). 2. Hammer drill nach.Anspruch 1, characterized in that the control housing consists of three parts (30, 32, 34) and only one part (34) is connected to the guide tube (60). 3. Hammer drill according to claim 2, characterized in that the lower part (34) of the control housing has or forms an insert (62), the surfaces in the sliding tube (60) (66) are integrally connected to this. 4. Hammer drill according to one of claims 1 to 3, characterized in that the sliding tube (60) and control housing (34) are additionally screwed together. 5. Hammer drill according to one of claims 2 to 4, characterized in that a pin (58) passes through the upper end of an integral with the associated control housing part (34) insert (62) and the sliding tube (60) sitting thereon. 6. Hammer drill according to claim 5, characterized in that the lower part (34) of the control housing with a buffer ring (27) on an inwardly directed collar (56) of a between the outer tube (12) and the upper cap (14) screwed jacket body (22nd ) supports and that the pin (58) extends radially at both ends to the collar (56). 7. Hammer drill according to claim 6, characterized in that the casing body (22) has a grooved profile (24) on the outside for engaging a correspondingly counter-profiled screwing tool. 8. hammer drill according to at least one of claims 3 to 7, characterized in that the surfaces (66) of the control housing (34, 62) in the sliding tube (60) form the radial closure of a plurality of web walls (64) adjoining one another in a star shape in cross section, between which axially extending air channels (67, 68) are present. 9. hammer drill according to at least one of claims 1 to 8, characterized in that the intermediate piston (80) in a in the outer tube (12) inserted, longitudinal grooves (79) having buffer sleeve (78) is guided. 10. Hammer drill according to claim 8 or 9, characterized in that at the lower end of the return stroke channel (68) in the sliding tube (60) at least one vent opening (74) is arranged such that Da.ß in the lower end position intermediate piston (80) there is no downward flow connection. 11 .. drill hammer at least according to claim 10, characterized in that the sliding: tube (60) in addition to the ventilation opening (74) to the return duct (68) for each exhaust duct (67) each has an outlet (69), in particular as an elongated hole or Slot is formed with a length matched to the stroke of the percussion piston (70). 12. Hammer drill according to claim 10 and 11, characterized in that the sliding tube (60) between the exhaust outlet (69) and the ventilation opening (74) in the exhaust channels (67) leading upper storage hole (71) and below the ventilation opening ( 74) has a lower shut-off bore (73) leading into the return stroke channels (68), the latter being smaller than the upper shut-off bore (71). 13. Hammer drill according to at least one of claims 1 to 12, characterized in that the intermediate piston (80) has a head (82) which is enlarged in diameter and that its narrower cylindrical body has radial outlets (84) at the lower end. 14. Hammer drill after. at least one of claims 1 to 11, characterized in that the drill bit (94) has axial channels (98) in the polygonal profile, which connect an annular space (88) at the lower end of the intermediate piston (80) to an annular gap (100) which passes through Recesses (112) at the lower end of the retaining cap (90) with respect to a lower collar (110) of the drill bit (94) has a constant flow connection to the outside. 15, rotary hammer according to claim 14, characterized in that the axial channels (98) are provided at the rounded corners or edges of the polygonal profile of the drill bit shank ( ₉ 6). 16. Hammer drill according to at least one of claims 1 to 15, characterized in that a collar (61) is arranged at the end of the sliding tube (60), which together with a to the sliding tube (60) coaxially movable valve body (59) forms a check valve. 17. Hammer drill according to at least one of claims 1 to 16, characterized in that at the head of the lower control housing part (34) air guide bores (52) are arranged, the axial portion of which is completely or partially closed at the end face by a threaded plug (54). ₁ 8. hammer drill according to at least one of claims 1 to 17, characterized in that the control housing (30, 32, 34) is penetrated by a central tube or bore (113, 114).

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