EP0658681A2 - Drill hammer - Google Patents

Abstract

In the bottom part, a pneumatic deep-hole hammer (10) has an outer tube (55), a control-housing shell (60) together with non-return valve (59), and a central tube (80) which has radial passages (81, 83) and on which a percussion piston (75) slides. The head of an axially displaceable drill bit (90) can be slipped onto the bottom end (84) of the central tube. A cylinder liner (70) guiding the piston (75) and the control-housing shell (60) are circumferentially welded to the outer tube (55) over an axial area (welding zone S, length l). Sitting above them is an adapter (40) which has top air passages (42), carries a blast ring (50) with nozzles (53) directed upwards, and is connected in a drive-transmitting manner to a sleeve (15) either directly or via a sliding piece (30) with guided shaft (20), which sleeve (15) sits under the connection cap (11). The bottom end (23) of the shaft (20) forms a control slide relative to the adapter top part (41), from which passages (42, 47) lead to a control-housing chamber (62) with passages (63). An annular chamber (68) follows below a tubular body (61) between outer tube (55) and cylinder liner (70). The free cross-section of the annular chamber (68) corresponds to the narrowest central bore (12, 22, 32, 42/47, 62, 82, 92) in the through components (11, 20, 30, 40, 61, 80, 87/90). Bores, passages and grooves (71, 72; 81, 83) in cylinder liner (70) and central tube (80) interact in a motion-controlling manner with recesses (76, 76') and bores (78, 78') of the piston (75). <IMAGE>

Description

The present invention relates to a pneumatically driven hammer drill, in particular a deep hole hammer, according to the preamble of claim 1.

Conventional drilling devices hammer in valve-controlled intermittent or continuous operation with a drill bit arranged on the foot part, which has passages for the compressed air, which is deflected at the bottom of the borehole and conveys loose cuttings upwards. With an in-hole hammer drill e.g. According to DE-A-2 705 191, a piston is guided on a central tube and, above it, a tube slide provided with transverse slots, which controls the pressurization of the hammer and also the blowing out in a relatively complex manner. The piston can also slide in a housing that is attached within an outer tube, but this can be problematic and prone to failure. The same applies to rotary hammers according to DE-B-2 062 690 and EP-A-0 484 672.

DE-U-9 202 336 describes a hammer drill of the type mentioned at the outset, which can also be used well in difficult rock. It has a rotatably driven tubular body for metering the blown air and a shaft which can be displaced therein and has a central passage, the lower end of which forms a shut-off element with the tubular body (or a sleeve part), for example a rotary or parallel slide, which releases an air deflection space as required or - possibly partially - closed. However, the neck of the shaft which is connected to the tubular body and a leading shaft can have a number of bores on the circumference provided pipe head are at risk of breakage due to relatively weak cross sections, especially since the length of the hammer drill acts on it with a large lever arm.

With the general aim of further improvement, the invention aims to create a rotary hammer of the type mentioned, which is simple in construction and economical to manufacture and which provides long service lives with great performance. The hammer should also be further developed so that it works relatively quietly even at an increased stroke frequency with low compressed air consumption.

Main features of the invention are set out in the characterizing part of claim 1. Refinements are the subject of claims 2 to 22.

In a pneumatically driven hammer drill, in particular a deep hole hammer, with an upper cap for connection to a compressed air source and, if appropriate, to a drill pipe, with an outer tube and a central tube with radial passages, which has a check valve upstream and which is firmly connected to a control housing, and with one on the outer tube at the bottom axially displaceably held drill bit, the head of which can be slid onto the lower end of the central tube, which leads a percussion piston guided in a cylinder liner, the invention provides according to claim 1 that the cylinder liner and the control housing casing with the outer tube at least partially form-fitting are firmly connected to a unit. This leads to significant advantages over comparable constructions, in which hammer drill failures frequently occurred due to fastening difficulties, which could cause considerable malfunctions. It was disadvantageous that the outer tube had to be in two or more parts, whereas the invention enables a homogeneous, one-piece outer tube. This ensures a high degree of operational reliability.

According to claim 2, the cylinder liner can connect to a shoulder in the outer tube with the same diameter and be fixed concentrically to the control housing jacket, e.g. by fitting the lower end of a tubular body, which advantageously contributes to the concentric anchoring of the cylinder liner.

In the embodiment according to claim 3, the control housing jacket is circumferentially welded flush with the outer tube without welding additives over an axial region, the length of the welding zone being the outer diameter of the outer tube is in a ratio of 1: 1 to 1: 2, preferably in a ratio of 1: 1.5 to 1: 1.8.

The outer grooves provided in claim 4 enable the attachment of screwing tools, which has great advantages in practical handling compared to the largely conventional clamping jaws.

From a fluidic point of view, it is favorable if the cylinder liner has outer ribs offset from one another in sections, which at the same time ensure reliable support on the outer tube. In particular, they are arranged axially parallel and in uniform ring arrangements so that their circumferential distance from the adjacent outer rib is two to five times, preferably about three times the width of the rib. Thanks to this dimensioning, there are large free cross sections in the contact area to the outer tube, which has an extremely advantageous effect on hammer operation. The air distribution is further favored by the measure of claim 7 that the outer ribs of axially successive ring arrangements are in a gap with each other, whereby partial deflections in the circumferential direction are possible, while at the same time ensuring good contact with the inner tube inner wall. The ring arrangements preferably have axial distances from one another of the order of magnitude of the rib length, so that to a certain extent compensation chambers are formed which contribute to the uniformity of the air flow.

An important design, for which independent protection is claimed, according to claim 9, is that the control housing jacket is screwed directly to the top of the cap or to a lower part of an adapter, the threaded connection of which is parallel to the welding zone essentially over its axial length or extends beyond. Such an adapter enables the hammer drill to be easily adapted to a wide variety of operating conditions, with the secure attachment always contributing significantly to a long service life.

According to claim 10, the adapter can have circumferential upper air ducts which open outward towards a sieve ring which is gripped by a filter ring resting on a shoulder of the adapter. This can according to claim 11 on the circumference upward, in particular evenly distributed bores, nozzles or the like. have, which open obliquely or curved in an upper outer region where the filter ring tapers, preferably conically protruding is. In this way, a blow ring is created which generates a suction in the manner of a jet pump through air deflection. As a result, the cuttings are quickly moved up and out.

An important contribution to the long-term stability of the rotary hammer according to the invention is made by the design according to claim 12, wherein between the adapter and the connection cap sits a drive-transmitting sleeve, the outer diameter of which is equal to that of the outer tube and which is drive-connected to the adapter directly or via a sliding piece with the shaft guided therein . The power transmission is therefore carried out with a very short shaft via two guide members seated directly one behind the other. The drive shaft is sleeve-protected, especially at the crucial fastening point directly behind the connection cap. As a result, vibrations, bending moments and the like, which emanate from the end of the hammer drill, unlike conventional constructions, cannot cause any damage to the upper part fastening, especially since such a hammer drill is particularly robust not only thanks to its relative brevity, but also because of that blowing ring attached to the adapter directly connects to the threaded connection sleeve.

With the design with sliding piece, which according to claim 13 can have a height-limited sliding guide for a profiled shaft, an additional control option for air flow division is achieved in a desired ratio. This makes it possible to lead central air to the drill bit on the one hand, and on the other hand to branch off blown air to the extent required. A favorable air supply is achieved in particular in that, according to claim 14, a ring distributor with channels for continuous blowing air is arranged between the connection cap and the sleeve. Furthermore, it is advantageous if, according to claim 15, the lower end of the shaft has a sliding opening for a connecting piece on the upper part of the adapter, which is used in this way for air control.

Claim 16 provides as a variant that the shaft has a control slide with passages and an annular surface below, which cooperates with a collar in the upper part of the adapter in an air-controlling manner, that a central passage in the sliding piece is connected to the flow with essentially axially parallel upper air ducts of the upper part of the adapter and that at least some of the passages communicate with the upper air ducts in an upper position of the shaft. It can be seen that the air control formed in this way is as simple as it is effective. With little effort, flow conditions can be established that both Intermittent as well as continuous operation of the rotary hammer make a significant contribution to economic efficiency.

In the development of claim 17, a valve seat for a check valve arranged on the control housing is present in the adapter, which can be held together with the associated valve spring on a base which has channels leading from the passage to a control housing chamber. This structure is as simple as it is stable. Especially in connection with the welding zone, through which the outer tube is rigidly connected to the cylinder liner, the valve holder through the base, which connects directly to the lower part of the adapter, has proven its worth. The further passages, channels, recesses etc. serve to supply air to the lower part of the hammer drill.

According to claim 18, the tubular body has radial bores which are connected to one another and to control housing radial bores by a puncture or annular space and which open into an annular chamber between the outer tube and the cylinder liner. The number, size and arrangement of these radial bores and the puncture assigned to them ensure perfect air flow for loading the piston. The annular chamber between the outer tube and the cylinder liner is very advantageous, the free cross-section according to claim 19 being at least as large as the narrowest under the central bores in the passage components of the hammer drill. This dimensioning ensures good air passage with at least substantially uniform flow resistance.

In a further embodiment of the air duct, the cylinder liner and the central tube have transverse or radial bores which are assigned to one another and can be released or closed by movement of the piston. Important improvements to the hammer drill operation can be achieved according to claim 21 in that channels, grooves, axial bores or the like, close to the circumference, of recesses, annular grooves or the like, which are delimited by control edges. the piston, which open on one of its end faces. It is of great advantage that the required passages can be manufactured very precisely in a relatively simple manner, the number, size and arrangement of the passages in turn influencing the impact characteristics as required. In addition, by the measures of claim 22, the amount of under air attacking on the underside of the piston can be controlled very appropriately so that the piston accelerates more upwards and less downwards is braked, whereby a high impact frequency is achieved and the impact force on the drill bit is increased.

Fig. 1

einen Längsschnitt durch einen Bohrhammer in Ausblas-Stellung.

Fig. 2

einen geteilten Längsschnitt durch einen Bohrhammer in zwei Arbeits-Stellungen,

Fig. 3

einen Längsschnitt durch einen Bohrhammer-Oberteil von vereinfachter Bauform,

Fig. 4

einen geteilten Längsschnitt durch einen Bohrhammer-Oberteil einer anderen Ausführungsform in zwei Arbeits-Stellungen,

Fig. 5a bis 5d

Seiten- bzw. Schnittansichten von Bestandteilen und Zusammenbau eines Blasringes,

Fig. 6

einen Längsschnitt durch einen Mittel- und Unterteil eines Bohrhammers noch einer anderen Bauform,

Fig. 7

eine Seiten- und Axialschnittansicht einer Zylinderbüchse und

Fig. 8a bis 8c

je eine Teil-Längsschnittansicht weiterer Varianten mit unterschiedlichen Kolbenstellungen.

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

Fig. 1

a longitudinal section through a hammer drill in the blow-out position.

Fig. 2

a divided longitudinal section through a hammer drill in two working positions,

Fig. 3

a longitudinal section through a hammer drill head of simplified design,

Fig. 4

2 shows a divided longitudinal section through a top drill part of another embodiment in two working positions,

5a to 5d

Side or sectional views of components and assembly of a blow ring,

Fig. 6

a longitudinal section through a middle and lower part of a hammer drill of yet another design,

Fig. 7

a side and axial sectional view of a cylinder liner and

8a to 8c

A partial longitudinal section view of other variants with different piston positions.

In the drawings, FIGS. 1a and 1b (= FIG. 1) as well as FIGS. 2a and 2b (= FIG. 2) are to be thought of as being put together. A hammer drill 10 is shown with a connection or screw cap 11 and a central passage 12, furthermore a threaded connection 13 with a subsequent sealing ring 14 to a screw sleeve 16 inside a sleeve 15, which guides a shaft 20. The head 19 is screwed to the sleeve 16, a central passage 17 being designed as a hexagon for inserting a screwing tool. The shaft 20 carries spline-like ribs 21, which cooperate in a form-fitting manner with an opposite profile (counter ribs 31) in the upper part of a sliding piece 30.

A central passage 22 leads to the lower end 23 of the shaft 20, where it has a collar 26 and a sliding opening 27 on the inside. A sliding guide 25 at the lower end 24 of the sleeve 15 guides a neck 35 of the sliding piece 30. This as well as the sleeve 15 and the screw cap 11 are provided with outer grooves R for attaching a screwing tool. The lower end 24 of the sleeve 15 is opposite a shoulder 34 of the sliding piece 30, which also has an inner stop 36 which faces the collar 26 of the shaft 20.

At the bottom, in the sliding piece 30, a transition space 32 connects to the upper part 41 of an adapter 40, with a flow connection to its central passage 42 and to the outside air channels 43. On the upper part 41, an upwardly projecting connecting piece 44 is formed. A blow ring 50 sits on a shoulder 46, the structure of which can be seen in detail from FIGS. 5a to 5d. Between the screw cap 11 and the upper part 41, the sleeve 15 encloses an annular space in which an annular distributor 103 with channels 104 for permanent blowing air can be located (FIG. 3).

In the middle part of the adapter 40, the passage 42 is flared until it merges into a chamber 47, the upper limit of which is designed as a valve seat 49. While the upper part 41 is screwed to the sliding piece 30 by a threaded connection 38, a threaded connection 48 on the lower part 45 serves for connection to an outer tube 55 which, like the adapter 40, has outer grooves R.

The outer tube 55 is welded on its upper part 56 in a welding zone S to a control housing jacket 60, specifically over an axial region of length ℓ, which corresponds approximately to that of the thread 38. A base 54 connects directly to the lower part 45 of the adapter 40 and serves as a holder for a check valve 59 with valve spring 58 and has channels 63 which open into a chamber 62 of the central tube 80.

The control housing casing 60 has radial bores 64 which can be offset from one another in the axial and circumferential directions. They open into a recess or annular space 65, which is connected in terms of flow via radial bores 67 to an annular chamber 68 which is located between the unit of outer tube 55 and cylinder liner 70 welded at the upper end. This ends at a shoulder 57 in the outer tube 55. It has upper radial bores 71 and middle radial bores 72.

In the control housing casing 60 there is a tubular body 61 which merges into the central tube 80, which has transverse bores 81 in the upper region and radial bores 83 in the lower region. Immediately above the lower end 84 of the central tube 80, it generally has a section 107 of reduced outer diameter (FIGS. 8a, 8b, 8c), but a uniformly shaped central tube 80 is also possible (FIG. 1b). In any case, a piston 75 slides on it, which is also guided in the cylinder liner 70. It has recesses or annular grooves 76, 76 'and axial bores 78, 78' close to the circumference. Its top surface 74 faces the bottom surface 69 of the tubular body 61. The bottom surface 79 of the piston 75 periodically strikes the opposing impact surface 89 of a drill bit 90 during operation.

The drill bit 90 has a shaft 87 with a shoulder 88 which is supported on a retaining ring 86. A buffer sleeve 85 is used to guide the upper part of the shaft 87. A passage 92 is designed towards the impact surface 89 as a sliding bore 91 which cooperates with the lower central tube end 84 in an air-controlling manner, which - as mentioned - is preferably offset in diameter. The drill bit 90 also has a retaining cap 93 with outer grooves R. The base of the drill bit 90 is provided in the usual way with passages and pins (not designated) or hard metal inserts.

The lower part of the hammer drill 10 is shown in Fig. 1 in the blow-out position, i.e. with the hammer raised in the borehole B and therefore the drill bit 90 hanging without basic contact. In the upper part, the collar 26 of the lower shaft end 23 bears against the stop 36 of the sliding piece 30 and has thus released the pin 44 of the adapter 40. The air flow supplied through the central bores 12, 22 of the cap 11 and shaft 20 divides, so that a partial amount of air passes through the passage 42 in the adapter 40 and loads the check valve 59 downwards, i.e. in the open position shown in Figure 1; the remaining air flows through the upper air channels 43 of the adapter 40 and through the sieve ring 51 as well as the nozzles or oblique bores 53 of the blow ring 50. The air deflection that occurs thereby causes a jet pump or venturi effect and consequently a suction that the Conveying cuttings from the bottom of the borehole. The number and size of the passages or channels and bores allows the partial air flows to be dimensioned as required.

In the blow-out position of FIG. 1, the hammer drill 10 is lifted off the bottom of the borehole, so that the drill bit 90 hangs on the retaining ring 86 with the shoulder 88 under the air pressure present and the piston 75 rests on the buffer sleeve 85. As a result, its top surface 74 exposes the radial bores 71 of the cylinder liner 70. The compressed air therefore flows through the channels 63 into the chamber 62 of the central tube 80 and via the bores 64/65/67 into the annular space 68, further along the outer tube 55 to the radial bores 71 and into the channels or axial bores 78, but also through the transverse bores 81 and through the central bore 82 of the control or central tube 80 and the passage 92 in the shaft 87 of the drill bit 90, so that the bottom of the borehole is blown free underneath.

In the working position of FIG. 2, the lower shaft end 23 surrounds the pin 44 of the adapter 40 in the upper part of the hammer drill 10, and the collar 26 closes the upper air channels 43. The compressed air supplied flows through the central bores or passages as a whole 12, 22, 42/47, 62, 82, 92 of components 11, 20, 30, 40, 61, 80, 87/90; as a result, the drill bit 90 of the hammer drill 10 processes the bottom of the borehole. For continuous blowing out, partial air quantities can be passed into the blow ring 50 by appropriately measuring or adjusting the annular gap between the collar 26 of the shaft 20 acting as a control slide and the pin 44 of the adapter 40.

At the same time, the lower part of the hammer drill 10 is in its working position (FIG. 2b on the left), in which the drill bit 90 is pressed into the bottom of the borehole and thus the piston 75 is raised. Its head surface 74 is above the thus closed radial bores 71, and the head of the drill bit shank 87 surrounds the lower end 84 of the central tube 80. In the resulting closed space 94 above the buffer sleeve 85, under air passes through the channels or axial bores 78 from the lower one Recess 76 of the piston 75. It is moved upwards until the supply of under air ceases as soon as the lower control edge 77 has passed over the radial bores 72 of the cylinder liner 70 (on the right in FIG. 2b). The air above the piston 75 is pushed out through the transverse bores 81 of the central tube 80 during the upward movement.

If the top surface 74 of the piston 75 has exceeded the height of the transverse bores 81 and has therefore formed a buffer space 95 below the bottom surface 69 of the control housing shell 60, air is stowed therein and the upward movement of the piston 75 is braked, the bottom surface 79 of which the radial outlet bores 83 of the Central tube 80 has released, whereby the under air relaxes.

As soon as the upper control edge of the recess 76 'overflows the radial bores 71 of the cylinder liner 70, compressed air passes through the channels or axial bores 78' into the buffer space 95 mentioned, which initiates the downward movement of the piston 75 and thus the stroke. The compressed air supply continues until the upper control edge of the recess 76 'has passed under the radial bores 71 (on the left in FIG. 2b) and has thereby closed the latter. The air located below the piston 75 is pushed out during its downward movement through the central tube 80 via its radial bores 83 until it passes as it passes the bottom surface 79 of the piston 75 are closed. With the new formation of the closed space 94, the next work cycle begins.

Fig. 3 shows the upper part of a design of the hammer drill 10, which is simplified by omitting the shaft 20 and sliding piece 30. The sleeve 15 attached to the cap 11 is screwed directly to the adapter 40 by the threaded connection 38. The compressed air supplied in this exemplary embodiment via the ring distributor 103 and its channels 104 flows in continuous blow mode via the passages 12, 42 into the lower part of the hammer drill (not shown here), the blowing again taking place through the upper air channels 43 and the blow ring 50. The dimensioning and number of channels or bores determines the ratio of the partial air quantities.

In the embodiment of the drill hammer upper part shown in FIG. 4, the lower end 23 of the shaft 20 forms a control slide with e.g. two ring surfaces 29, 29 'arranged one above the other at a predetermined distance and a number of passages 28, 28', 28 '' located next to them. When the rotary hammer 10 is pressed (left in FIG. 4), the upper annular surface 29 'closes the entrance of the passage 42 in the adapter 40. The entire air flow therefore passes through the passages 12, 22, 28' / 28, 42 of the components 11, 20/23, 40 in the screwed lower part of the rotary hammer 10 (not shown here).

While the designs described above work in the intermittent mode, in which the hammer drill 10 stops beating by lifting the drill bit 90 from the bottom of the borehole and then only the borehole B is blown free, one achieves with the control slide construction according to FIG. 4 in connection with the Design according to FIGS. 8b and 8c in a surprisingly simple way, continuous operation with exact metering of the partial air quantities. The piston 75 therefore continues to move up and down in the raised hammer state; the resulting shaking is desirable in some rock formations, but indispensable in others (e.g. in the case of overburden, clay inclusions, cracks, cracks, etc.). By appropriately reducing the partial flow entering the lower part of the hammer through the control slide 23, the piston stroke and consequently the impact energy are throttled in such a way that overstraining or even self-destruction of the hammer drill 10 is avoided with certainty.

Since the remaining amount of partial air exits through the upper air channels 43 in the adapter 40 and through the bores or nozzles 53 of the blow ring 50, good blowing out of the borehole B is ensured. If it should be intensified, you can do that Expand the annular space between the collar 37 and the or each annular surface 29, 29 'of the control slide 23 in accordance with the desired partial air throughput. Optionally or alternatively, additional passages 28 ″ above the upper ring surface 29 ′ can be provided and dimensioned accordingly.

In the hanging state (on the right in FIG. 4) of the drill bit 90, the air flow introduced via the passage 22 is divided. Then the upper air flows partly through the passages 28 ', 43, 53 upwards into the open and a partial flow goes down through the bottom passage 28 and through a narrow annular space which is present between the annular surface 29 and the collar 37 the lower part of the hammer drill. Here too, the partial air volumes can be adjusted as required by suitable dimensioning of the ducts or bores and the annular spaces.

Fig. 6 shows a further version of a hammer drill 10 with valve control and with adjustable under air. Components of the same type are identified with the same reference numbers as before. A central tube 80 is also provided, but a ribbed cylinder liner 70 and a control valve 97 in a control housing jacket 60 which is axially welded to the outer tube 55. If the hammer 10 is not pressed against the bottom of the borehole, the lower edge 79 of the piston 75 lies on top of it Buffer sleeve 85 on. However, as soon as the hammer 10 is pressed on, the drill bit 90 lifts the piston 75. When the upper control edge 77 of its recess 76 overflows the bores 72 of the cylinder liner 70, under-air flows through the channels 78 into the closed space 94 below the piston 75, which consequently moves upwards. During the return stroke, the piston 75 pushes the air above it through the outlet bores 81 of the central tube 80. As soon as the piston 75 on the one hand with its upper edge 74 has overflowed the upper edge of the outlet bores 81 and on the other hand with its lower edge 79 the radial bores 83, the space 94 is vented, so that the valve 97 is reversed and the blow air is released.

6 shows a control valve 97 (of the flapper valve type) in a neutral position; however, other control valves are also readily usable. If the valve plate mounted on a central support, a kind of cutting edge 98, of the control housing 96 tilts to the right, the left side opens and the air can enter the chamber 62 of the central tube 80 and through holes (not shown) which are provided in the control housing 96 Flow through holes 99 in the space between the upper edge 74 of the piston 75 and the lower edge 69 of the control housing casing 60. When the piston 75 moves down, the space above the piston relaxes as soon as its top edge 74 hits the The upper edge of the outlet bores 81 overflows in the central tube 80. If the lower edge 77 of the piston 75 has overflowed the outlet bores 83 of the central tube 80 and has thus released them, the valve plate tilts to the left; it closes the blow air bores and opens the return stroke bores (not shown) in the control housing 96 on the right.The latter open into a collecting bore 100. From there, the air enters a puncture or annular space 65 and through radial bores 67 into the annular chamber 68, which is between the cylinder liner 70 and the outer tube 55 is formed. Finally, the air flows through the bores 72 of the cylinder liner 70 into the recess 76 of the piston 75, so that a new work cycle begins.

It is important that the control of the hammer drill according to the invention via the central tube 80 allows a high number of strokes regardless of the shaft length of the piston 75, namely because of the large-area attack of the full amount of under air on the piston underside with a correspondingly rapid upward acceleration. This is in positive contrast to conventional rotary hammers, which only have a relatively narrow annular space available for the sub-air - either with a piston without a bore or one with a bore but without a central tube - and strive for high individual impact force, which is associated with a lower working frequency . According to the invention the under air can be controlled so that the piston 75 e.g. closes the under-air inlet 72 after a third of its return stroke. By switching off the under air, a relaxation process already takes place in (brake) room 94. If the piston 75 goes down into this closed space 94 during the stroke, as a result substantially less air is displaced than in a space filled over the entire upward path. As a result, the piston 75 is also accelerated more downwards, so that it brings a higher energy to the drill bit thanks to less braking.

A variant of this is a massive piston design (not shown) without axial bores or annular grooves, the under-air inlet 72 being pulled down so far that the air flowing in when the drill bit 90 is pressed in engages under the piston 75.

8a to 8c show designs in which the piston 75 guided on the central tube 80 is immersed in a buffer sleeve 85. Regardless of the shaft length of the piston 75, the lower air is controlled via the radial bores 83 in the central tube 80. (On the other hand, conventional constructions without a central tube the piston skirt must be so long that it gets under air over a sufficiently large distance.)

The invention is not limited to the described embodiments, but can be modified in many ways. For example, for the cost-effective manufacture of an adapter 40 of high strength, instead of circumferential bores, some grooves on the outside of the thread 38 can be made up to the height of the blow ring 50. 7 shows a modified cylinder liner 70 which is provided with a multiplicity of outer ribs 101. These are arranged in ring arrangements 102 at axial distances p from one another in such a way that, with good support on the outer tube inner wall, a large through-flow volume is ensured. The individual ring arrangements 102 are preferably set to one another with a gap, that is to say offset to one another in the circumferential direction, preferably by half the circumferential distance w. This is a multiple of the rib width n, in particular two to five times. The axial distance p can correspond approximately to the rib length m, but can also be shorter, so that the ring arrangements 102 follow one another more closely.

6a shows the central part of a rotary hammer designed for intermittent operation. In the blow-out position shown, the piston 75 rests on the buffer sleeve 85, closes the under-air inlet 72 and has cleared shut-off and blow-out holes 106 at the top .

Similarly, FIGS. 8b and 8c - analogously to FIGS. 4 and 6 - show the central part of a continuously striking rotary hammer, with the drill bit 90 still sagging in FIG. 8b, so that the elongated and thickened lower end 84 of the central tube 80 the sliding bore 91 of the Shaft 87 closes. In this position, the top of the rotary hammer (Fig. 4) delivers a reduced amount of air. It is expediently metered in such a way that the piston 75, when moving downwards, itself generates a buffering in the closed space 94, which prevents the piston 75 from touching the buffer sleeve 85 and the drill bit 90. The incoming under air then drives the piston 75 upward (FIG. 8c); as soon as it closes the outlet 81 in the buffer space 95, the oscillating piston movement occurs.

It can be seen that, according to the invention, a pneumatically driven deep hole hammer generally has an outer tube 55, a control housing jacket 60 together with a check valve 59 and a central tube 80 having radial passages 81, 83 on which a percussion piston 75 slides. The head of an axially displaceable The drill bit 90 can be slid onto the lower, preferably stepped central tube end 84. A possibly ripped cylinder liner 70 guiding the piston 75 and the control housing jacket 60 are circumferentially welded to the outer tube 55 over an axial region (welding zone S, length ℓ). Above the control housing there is an adapter 40 which has upper air channels 42 and which carries a blow ring 50 with upward-directed nozzles 53. Below the connection cap 11, a drive-transmitting sleeve 15 is connected to the adapter 40 directly or via a sliding piece 30 with a shaft 20 guided therein. The lower end 23 thereof can form a control slide relative to the adapter upper part 41, from which passages 42, 47 lead to a control housing chamber 62 with channels 63. Below a tubular body 61, between the outer tube 55 and the cylinder liner 70, there is an annular chamber 68, the free cross section of which is at least as large as the narrowest of the central bores 12, 22, 32, 42/47, 62, 82, 92 in the passage components 11, 20, 30, 40, 61, 80, 87/90. Bores, channels and grooves 71, 72; 81, 83 in cylinder liner 70 and central tube 80 interact with recesses 76, 76 'and bores 78, 78' of piston 75 to control movement.

All of the features and advantages arising from the claims, the description and the drawing, including structural details and spatial arrangements, can be essential to the invention both individually and in the most varied of combinations.

Reference symbol list

B

Borehole

D

outer diameter

R

External grooves

S

Welding zone

ℓ

Axial range

m

Rib length

n

Rib width

p

Axial distance

w

Circumferential distance

10th

Hammer drill

11

Screw cap

12th

Passage

13

Thread (connection)

14

Sealing ring

15

sleeve

16

Screw sleeve

17th

Hexagon passage

18th

Thread (connection)

19th

head

20th

wave

21

Rib profile

22

Passage

23

lower end (of 20)

24th

lower end (of 15)

25th

Sliding guide

26

Federation

27

Sliding opening

28.28 ', 28' '

Culverts

29.29 '

Ring surfaces

30th

Sliding piece

31

Inner profile (counter ribs)

32

Transition room

34

shoulder

35

neck

36

attack

37

collar

38

Thread (connection)

39

Spacer ring

40

adapter

41

Top

42

Passage

43

Upper air channels

44

Support

45

Lower part

46

shoulder

47

chamber

48

Thread (connection)

49

Valve seat

50

Blow ring

51

Sieve ring

52

Filter ring

53

Nozzles (bore)

54

base

55

Outer tube

56

Top

57

paragraph

58

Valve spring

59

check valve

60

Timing case jacket

61

Tubular body

62

chamber

63

channels

64

Radial bore

65

Puncture / annulus

66

Sealing ring

67

Radial bores

68

Ring chamber

69

Floor area

70

Cylinder liner

71.72

Radial bores (72: under-air inlet)

73

lower end (of 70)

74

Head area

75

piston

76.76 '

Cutouts / ring grooves

77.77 '

Control edge (s)

78.78 '

Axial bores

79

Floor area

80

Central tube

81

Cross bores / outlet

82

Central bore

83

Radial bores

84

lower end (of 80)

85

Buffer sleeve

86

Retaining ring

87

shaft

88

shoulder

89

Impact area

90

Core bit

91

Slide hole

92

Passage

93

Retaining cap

94

(closed room

95

Buffer space

96

Timing case

97

Control valve

98

Cutting edge / central support

99

Holes

100

Collecting holes

101

Outer ribs

102

Ring arrangement

103

Ring distributor

104

channels

105

narrow end part (of 75)

106

Parking and blow-out hole

107

stepped section

Claims (22)

Pneumatically driven hammer drill, in particular deep hole hammer (10), with an upper cap (11) for connection to a compressed air source and optionally to a drill pipe, with an outer tube (55) and a central tube (80) having radial passages (81, 83), the A check valve (59) is arranged upstream and is fixedly connected to a control housing jacket (60), and to a drill bit (90) which is axially displaceably held at the bottom on the outer tube (55) and whose head rests on the lower end (84) of the central tube (80). can be slidable over it, which carries a percussion piston (75) guided in a cylinder liner (70), characterized in that the cylinder liner (70) and the control housing jacket (60) are at least partially positively connected to the outer tube (55) to form a unit are. Hammer drill according to claim 1, characterized in that the cylinder sleeve (70) connects with its lower end (73) to a shoulder (57) in the outer tube (55) of the same diameter and is fixed concentrically on the control housing casing (60), for example by fitting the lower end of a tubular body (61). Hammer drill according to claim 1 or 2, characterized in that the outer tube (55) is circumferentially welded flush with the control housing jacket (60) without weld fillers, in particular over an axial area (welding zone S, length ℓ) such that the length (ℓ ) of the welding zone (S) to the outer diameter (D) of the outer tube (55) in a ratio of 1: 1.5 to 1: 1.8. Hammer drill according to Claim 3, characterized in that components (11, 15, 30, 40, 93) with the same diameter as the outer tube (55) have outer grooves (R), namely the outer tube (55) itself on its upper part (56) in the region of the Welding zone (S). Hammer drill according to one of claims 1 to 4, characterized in that the cylinder liner (70) has outer ribs (101) offset in sections from one another. Hammer drill according to claim 5, characterized in that the outer ribs (101) are axially parallel and are formed in uniform ring arrangements (102) so that their circumferential distance (w) to the adjacent outer rib is two to five times, preferably three times the rib width (n ) is. Hammer drill according to claim 5 or 6, characterized in that the outer ribs (101) of axially successive ring arrangements (102) are in a gap with each other. Hammer drill according to claim 6 or 7, characterized in that the ring arrangements (102) have axial distances (p) from one another of the order of magnitude of the rib length (m). Hammer drill at least according to one of Claims 1 to 8, characterized in that the control housing casing (60) is screwed directly to the top of the cap (11) or to a lower part (45) of an adapter (40), the threaded connection (38 ) extends parallel to the welding zone (S) essentially over its axial length (ℓ) or beyond. Hammer drill according to Claim 9, characterized in that the adapter (40) has upper air ducts (43) close to the circumference, which open outwardly on a sieve ring (51) which is connected by a filter ring (1) which rests on a shoulder (46) of the adapter (40). 52) is composed. Hammer drill according to claim 10, characterized in that the filter ring (52) on the circumference upwards, in particular uniformly distributed bores, nozzles (53) or the like. has, which open obliquely or curved in an upper outer region, where the filter ring (52) tapers, preferably conically protruding. Hammer drill at least according to one of claims 9 to 11, characterized in that between the adapter (40) and the connecting cap (11) sits a drive-transmitting sleeve (15), the outer diameter of which is equal to that (D) of the outer tube (55) and which the adapter (40) is directly connected to the drive (FIG. 3) or via a sliding piece (30; FIGS. 1, 2, 4) with a shaft (20) guided therein. Hammer drill according to claim 12, characterized in that the sliding piece (30) has a height-limited sliding guide (25) for a profiled shaft (20) by a neck (35) of the sliding piece (30) slidable in the sleeve (15) into one Rib profile (21) of the shaft (20) has the same inner profile (31), and that a collar (26) of the shaft (20) faces a stop (36) of the sliding piece (30). Rotary hammer according to claim 12 or 13, characterized in that an annular distributor (103) with channels (104) for continuous blowing air is arranged between the connection cap (11) and the sleeve (15). Hammer drill according to one of claims 12 to 14, characterized in that the lower end (23) of the shaft (20) has a sliding opening (27) for a connecting piece (44) on the upper part (41) of the adapter (40). Rotary hammer according to one of claims 12 to 15, characterized in that the shaft (20) has a control slide (23) at the bottom with passages (28, 28 ', 28'') and an annular surface (29, 29') with a Collar (37) in the adapter upper part (41) cooperates in an air-controlling manner that a central passage (32) in the sliding piece (30) is connected to the flow with essentially axially parallel upper air channels (43) of the adapter upper part (41) and that at least some of the Passages (28 ', 28'') in an upper position of the shaft (20) are connected to the upper air ducts (43). Hammer drill according to one of claims 9 to 16, characterized in that a valve seat (49) for the check valve (59) arranged on the control housing jacket (60) is formed in the adapter (40), which includes the associated valve spring (58) on a base (54) which has channels (63) leading from the passage (42) to a control housing chamber (62). Rotary hammer according to one of claims 2 to 17, characterized in that the tubular body (61) has radial bores (64) which are connected to one another and to control housing radial bores (67) which penetrate into an annular chamber by means of a recess or annular space (65) (68) between the outer tube (55) and the cylinder liner (70) open. Rotary hammer according to claim 18, characterized in that the free cross-section of the annular chamber (68) is at least as large as the narrowest under the central bores (12, 22, 32, 42/47, 62, 82, 92) in the passage components ( 11, 20, 30, 40, 61, 80, 87/90) of the hammer drill (10). Rotary hammer according to one of claims 1 to 19, characterized in that the cylinder sleeve (70) and the central tube (80) are assigned to transverse or radial bores (71, 72; 81) which are associated with one another and can be released or closed by movement of the piston (75) , 83). Hammer drill according to claim 20, characterized in that of recesses (76), annular grooves or the like, which are delimited by control edges (eg 77, 77 '), channels, grooves, axial bores (78, 78') or the like close to the circumference. go out of the piston (75), which open on one of its end faces (74 and 79). Hammer drill according to claim 20 or 21, characterized by such designs and dimensions of the bores (71, 72; 81, 83), recesses (76), axial bores (78, 78 ') etc. that the piston (75) in cooperation with the Control valve (97) closes the under-air inlet (72) (81) after a predetermined proportion, for example a third, of the return stroke.

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