EP0004946B1 - Bore hole hammer, especially down-the-hole hammer - Google Patents

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 device supported on the cap, control body and with the control device positively connected cylindrical slide tube which can be moved up and down along a drilled percussion piston in the outer tube, and with a radially divided lower retaining cap of disharmonious polygon inner profile, in which a likewise drilled-through polygon shaft of a drill bit provided with flushing bores is movably held up and down.

Such hammer drills are known from DE-A-26 09 376. In a similar configuration, but without polygonal profile elements, DE-A-23 62 724 and GB-A-1 419981 also describe deep hole drilling hammers, in which, however, the sliding tube itself is movably mounted up and down and protrudes into the head of the drill bit , which has considerable disadvantages. In rough drilling operations, the lower hammer parts experience wear relatively quickly, which can lead to canting of the drill bit with a 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 event of sudden holes or caverns in the rock, the actual drilling work stops 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 slide tube and that the lower part of the control device has or forms an insert, the surfaces of which in the slide tube are positively connected to it.

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 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 which 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 embodiments according to US Pat. Nos. 2,661,928 and 2,851,251, where an upper and a lower piston can tilt very easily and the buffer effect caused by the invention is missing.

Developments of the invention according to claims 2 to 4 offer great advantages in terms of production technology and ensure additional securing of the positive connection between the guide tube and control device. 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 4 and 5 and its outer groove profile allow the hammer to be opened much more easily than before in the event of malfunctions or chisel changes. Conventional rotary hammers can sometimes not be loosened at all, while others in the casing are severely weakened and have predetermined breaking points. In many cases, the application of 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 6 creates a multi-channel inner tube control system that works extremely reliably with a simple and stable structure. A four-channel system with intersecting pairs of opposite exhaust and return stroke channels is particularly favorable; this ensures that the air flows out very evenly and the piston cannot jam.

A particularly good coordination is achieved by the features of claims 7 and 8 between the buffering area and the lower opening to the return stroke channel. The dimensioning can be such that the greatest performance is achieved with a half-sagging drill bit, while with increasing bit travel there is a gradual decrease in performance until pure buffer operation, which prevents the bit 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.

An advantageous simplification further consists in the measures of claim 9, since - in contrast to the prior art - only minimal machining of the sliding tube is necessary. Several, distributed over the length of the guide tube for each channel provides the embodiment according to claim 10, wherein an air extension takes place through the upper shut-off hole, which has a larger width than the lower shut-off hole leading into the return stroke channel, despite the intermediate piston located in the lower end position can. Therefore, the hammer can continue to run while the buffering 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 11 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 12 and 13 ensures perfect air flow in any axial position of the drill bit. The disharmonious polygon profile is not only cheaper for rotating entrainment than any involute tooth system; but also enables axial luit guide channels 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 hammer part above the control unit, so that when the hammer was switched off, its lower part was fully exposed to the penetration of cuttings, dust, water, etc. In addition, a threaded stopper provided according to claim 15 on the head of the lower control housing part can, if necessary, be designed as a nozzle which, with a predetermined cross-section, enables additional air passage if desired. The control can be changed as required by replacing the threaded plug. It can be omitted if, for use as a hammer drill with water flushing, 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. lb der Schnittführung entsprechend der Linie Ib-Ib von Fig.4 entspricht,
• Fig. 2 einen Längsschnitt durch einen unteren Steuervorrichtungsteil mit Gleitrohr,
• Fig.3 einen Querschnitt entsprechend der Linie 111-111 in Fig. unter Weglassung des dort gezeichneten Sicherungsstiftes,
• Fig.4 einen Querschnitt entsprechend der Linie IV-IV in Fig. 1 b,
• 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. It shows

• 1a + 1b an overall longitudinal sectional view of a rotary hammer according to the invention, the lower part of FIG. 1b corresponding to the cut according to line Ib-Ib of FIG. 4,
• 2 shows a longitudinal section through a lower control device part with a sliding tube,
• 3 shows a cross section along the line 111-111 in Fig., Omitting the locking pin drawn there,
• 4 shows a cross section along the line IV-IV in Fig. 1 b,
• 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 20. 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 device is supported on the cap 14 in the jacket body 22 via buffer rings 26 and 27, which can be made of elastomers such as polyurethane. The upper part 30 has 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 between a valve support 42 of the control device middle part 32 and the valve seat 38 of the upper part 30 in Movable axially back and forth and guided centrally in the central part 32. The latter is provided with a number of oblique channels 44 distributed over the circumference and, following the control body 40, with a chamber 48. In the central part 32 of the control device, outer and side channels 46 lead to the head of the lower part 34, at least one of which opens out at bores 52 which are machined into the head of the lower part 34 of the control device.

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 device lower part 34, on which a sliding tube 60 connected to it integrally is seated. To secure this attachment, a screw connection (not shown) may be present. Optionally or additionally, the lower part 34 or the insert 62 and the sliding tube 60 are penetrated by a cross section 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. 1 b and 2, may be somewhat shorter.

At the lower end of the sliding tube 60, as shown in FIG. 2, there can be 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 its end, to which nuts 63a can be screwed in a suitable manner, by means of a compression spring 65 which partially dips into 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 of the insert 62 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 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 provided 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 screwed into the outer tube 12 from below, serves to fasten both the buffer sleeve 78 and a drill bit 94. Inside, the holding cap 90 has a disharmonious polygonal profile, in particular of the PC4 type, as described in DE-A-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 fluid communication with the space outside of 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 polygon 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 into the upper annular space 86, the compression space 76 located above prevents the impact piston 70 from striking through its air cushion. Rather, the impact piston 70 springs back upwards, whereby - if the other requirements are met - drill bits 94 and intermediate piston 80 can also drive back. 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 a vibration effect, bring about high gas accelerations and thereby substantially support the drilling work or enable intermittent operation with correspondingly dimensioned shut-off holes 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 retaining cap 90. Between this and the drill bit there is a practically wear-free polygon guide, which allows the transmission of torques over 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 device 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 facilitate and accelerate maintenance and repair work 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 drill according to DE-A-26 09 376, the versatility of use and the cost-effectiveness of use are considerably increased.

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

Claims (16)

1. Pneumatically driven drill hammer, in particular down-hole hammer, including an outer tube (12) and a through-hole (20) in a top cap (14) for connection to a compressed air source and, if applicable, to a drilling string, including control means (30, 32, 34) positively engaged to said cap (14), valve body (40) and cylindrical slide tube (60) positively connected to said control means, along which slide tube a ram (70) provided with a through-hole is movable up and down within said outer tube (12), and including a radially divided lower retainer (90) of disharmonic polygon-shaped inner profile within which a polygon shaft (96) likewise provided with a bore (102) of a bit (94) having bores for flushing is held for movement up and down, wherein an intermediate ram (80) is arranged between said ram (70) and the head (106) of said bit (94) and is at least partly guided on said slide tube (60), and wherein the lower portion (34) of said control means comprises or forms an inset portion (62) having lands (66) that engage said slide tube (60) and are positively connected thereto.

2. Drill hammer according to claim 1, wherein said slide tube (60) and the lower part (34) of said control means are, in addition, screw-joined to each other.

3. Drill hammer according to claim 1 or claim 2, wherein a pin (58) extends transversely through the upper end of said inset portion (62), which is integral with the associated portion (34) of said control means, and through said slide tube (60) itself which is seated on said inset portion.

4. Drill hammer according to claim 3, wherein said lower portion (34) of said control means engages, via a ring pad (27), an inwardly extending collar (56) of a cage (22) screw-joined between said outer tube (12) and said upper cap (14), and wherein both ends of said pin (58) extend radially up to said collar (56).

5. Drill hammer according to claim 4, wherein the outside of said cage (22) ist provided with a fluted profile (24) for engagement of a matching screwing tool.

6. Drillhammer according to any one of the preceding claims, wherein the lands (66) of said inset portion (62) at the lower portion (34) of said control means, engaged to said slide tube (60), form the radial ends of a plurality of partitions (64) which are joined starwise, in cross section, and between which there are axially extending air passages (67, 68).

7. Drill hammer according to at least one of the preceding claims, wherein said intermediate ram (80) is guided in a padding sleeve (78) that is inserted in said outer tube (12) and has longitudinal grooves (79).

8. Drill hammer according to claim 6 or 7, wherein on said slide tube (60), there is at the lower end of the backpressure passage (68) at least one venting port (74) dimensioned such that there is no downward flow connection if said intermediate ram (80) is in its lowermost position.

9. Drill hammer at least according to claim 8, wherein said slide tube (60) comprises, in addition to said venting port (74) towards said backpressure passage (68), one exhaust port (69) each for the exhaust passages (67), each of said exhaust ports being shaped as an elongated hole or slot whose length is tuned to the stroke of said ram (70).

10. Drill hammer according to claim 8 or claim 9, wherein said slide tube (60) comprises, between said exhaust port (69) and said venting port (74), an upper stopping bore (71) opening to said exhaust passages (67) and further comprises, below said venting port (74), a lower stopping bore (73) opening to said backpressure passages (68) and being smaller than said upper stopping bore (71).

11. Drill hammer according to at least one of claims 1 to 10, wherein said intermediate ram (80) comprises a head (82) the outside diameter of which is enlarged, and wherein its more narrow cylindrical body is provided, at the lower end thereof, with radial outlets (84).

12. Drill hammer according to at least one of claims 1 to 11, wherein said bit (94) is provided, in said polygon profile, with axial flutes (98) connecting a lower ring chamber (88) at the lower end of said intermediate ram (80) to an annular padding space (100) which has a permanent flow connection to ambiance owing to recesses (112) at the lower end of said retainer (90) opposite to a lower shoulder (110) of said bit (94).

13. Drill hammer according to claim 12, wherein said axial flutes (98) are arranged at the rounded corners or edges of the polygon profile of said bit shaft (96).

14. Drill hammer according to at least one of claims 1 to 13, wherein there is, at the end of said slide tube (60), a facing collar (61) that forms, together with a valve sleeve (59) that is movable coaxially to said slide tube (60), a check valve.

15. Drill hammer according to at least ohne of claims 1 to 14, wherein there are, at the head of the lower portion (34) of said control means, exhaust ports (52) the facing axial portion of which ist wholly or partly closed by a thread plug (54).

16. Drill hammer according to at least one of claims 1 to 15, wherein a central tube and/or bore (113, 114) extends through said control means (30, 32, 34).

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