GB1583848A

GB1583848A - Combination of a hammer drill or rotary hammer drill and a a tool a plug-in adaptor and a coupling means

Info

Publication number: GB1583848A
Application number: GB3659977A
Authority: GB
Original assignee: DUSS MASCHF
Current assignee: DUSS MASCHF
Priority date: 1976-09-01
Filing date: 1977-09-01
Publication date: 1981-02-04
Also published as: FR2363691A1; FR2363691B1; NL7709394A; DE2639310C2; DE2639310A1; CH624336A5

Abstract

The tool (10) of a percussive hammer, which tool (10) can be acted upon by a percussion element (21), passes with its shank (10') through a hollow adaptor (13, 13') and is coupled to the latter while maintaining axial play. The rear end of the shank (10') is acted upon directly by the percussion element (21). Thus, compared with a known percussive hammer in which the blows are transmitted to the tool shank (10') via a rod-shaped impulse transmitter mounted in the hollow adaptor (13, 13'), functional disturbances in the axial play between shank (10') and adaptor (13, 13') are reliably avoided. <IMAGE>

Description

(54) A COMBINATION OF A HAMMER DRILL AND A TOOL, A PLUG-IN ADAPTER, AND A COUPLING MEANS (71) We, FRIEDRICH DUSS MASCHINEN FABRIK GmbH & Co., of 7261 Neubulach, West Germany, a German Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a tool, a combination of a hammer drill or rotary hammer drill and a plug-in adapter, and a clamping means. The hammer drill includes a percussion element to impart axial blows to the tool.

Plug-in adapters make it possible and economical to use tools of different types and sizes with a single hammer drill of which the tool socket conforms to the plugin end of the adapter. Costs are further reduced because the different tools to be connected in the adapter, while having identical connecting or coupling members, are without plug-in ends proper, which would otherwise have an appreciable effect on costs. The cost saving is obtained both when different adapters are used for different hammer drills and when one adapter is used in connection with a particular type of hammer drill for different tools.

When using adapters it is customary to connect the tool shank rigidly to the adapter, so that the impact energy of the axial blows is transmitted to the tool by way of the adapter in every case. As a result the rhythmic transmission of the impact energy produces high friction losses at the components attaching the tool shank to the adapter, leading to marked heating of the attachment or coupling zone, particularly since in the hammer drills concerned the striking frequency is exceptionally high and the axial striking amplitude very small (see for example U.S. Patent Specification No.

3 690 390, German Offenlegungsschriften 2 440 082, 2448 377 and 2459 134, and German Gebrauchsmuster Specifications 7416174 and 7335672). Moreover, the mass of the unit comprising the tool and adapter is relatively large, compared with that of the tool alone, which means a further loss of impact energy.

In order to reduce these losses of impact energy owing to the releasable rigid connection and owing to the relatively high mass of the unit comprising the tool and adapter, one known assembly of the type initially described (German Offlenlegungsschrift 2 432 105) omits the rigid connection between the adapter and the tool shank.

The mass of the adapter can then cause little or no damping of the impact energy. In this case the blows from the percussion element are transmitted to the tool by a rod-like or tubular member (blow transmitter) which is slidably mounted in an axial bore in the adapter. The use of the blow transmitter produces a remarkable increase in drilling efficiency. The principal cause of this is that the adapter now no longer performs a blow transmission function, but acts purely as an adapter.

It has now been found that the increase in efficiency obtainable with ablow transmitter often cannot be maintained permanently at the original level. On the contrary, the efficiency drops sharply, particularly under severe stress after a long operating time, simultaneously with operating faults connected with the axial clearance of the adapter.

Another reason for the drop in efficiency may be that, for example when high drilling pressures are applied during the drilling of deep holes, coaxiality of the tool, which penetrates a relatively short distance into the adapter and is therefore not satisfactorily guided in the coupling zone, is not adequately ensured, so that additional frictional effects are produced by tilting in the coupling zone due to the axial play required between the tool and adapter. However, once there is a deterioration in the axial play between the adapter and tool which determines drilling efficiency, local heating and deformation in the coupling zone lead to further faults of axial clearance.Eventually the coupling elements may seize, so that the adapter and tool again form a more or less rigid unit of large mass and also the prime function of the adapter -- ease of tool change -- is no longer fulfilled.

Without fully clarifying the relationship between the above-mentioned operating faults connected with the axial clearance of the adapter, it has now been seen that the drop in efficiency mentioned is not found if, in a tool assembly of the type initially described, the tool shank extends through the axial bore in the adapter to within striking range of the percussion element of the hammer drill and can be struck directly by the latter.

Accordingly the present invention consists in a combination of a hammer drill or rotary hammer drill having a percussion element and a tool socket, a tool, a plug-in adapter and a coupling means, the tool having a shank, the plug-in adapter being adapted to be received by the tool socket, wherein the adapter has a continuous axial bore in which the tool is coupled by the coupling means which comprises at least one coupling element engaging both in a recess in the tool shank and in a recess in the adapter bore, so that the tool shank extends to within striking range of the percussion element of the hammer drill or rotary hammer drill and is adapted to be struck directly by the percussion element.

With this arrangement the tools are dearer owing to the lengthening of the shank, which may extend right through the axial bore in the adapter. This increase in cost is acceptable, however, because the drop in efficiency mentioned can be avoided reliably by means of the invention even if stresses occur during prolonged use or by drilling deep or wide holes.

The increase in efficiency obtainable by means of an assembly embodying the invention compared with the prior art initially described is in any case independent of the operating time and the degree of stress applied.

This is especially true if the axial dimension of at least two diametrically opposed, cylindrical coupling elements is at least double the diameter of the tool shank in the vicinity of the locking elements.

In comparison with the transmission of the impact energy by means of blow transmitters, moreover, the energy losses arising at the joint between the tool shank and blow transmitter are eliminated.

Advantageously, auger flights mountable on the tool shank may be locatable axially at the rear by a screw-threaded sleeve engaging the adapter.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawing.

In the drawing: Figure 1 illustrates the tool and adapter as combined with an electro-pneumatic rotary hammer drill; Figure 2 represents a cross-section along the line II-II of Figure 1; and Figure 3 represents a cross-section along the line III-III of Figure 1.

The tool comprises a drill bit 11, with a shank 10, and auger flights 12. The rear portion 10b of the shank is cylindrical and of smaller diameter than the tapering or conical portion of the shank 10d which carries the drill bit 11. The auger flights 12, which can be slid on to the tool shank from behind, embrace the conical shank portion 1 0d They are located axially both by the drill bit 11 and, directly or indirectly, by the adapter 13. One end 13' of the adapter 13 is received by a tool socket 22 of the rotary hammer drill. The rotary drive for the tool socket is by way of a drive shaft 23 and a driving pinion 23' which meshes with the driving gear 22' for the tool socket 22.The torque is transmitted from the driving gear 22' to the adapter 13, by the hexagonal rear end 13', which engages a corresponding socket portion in the tool socket 22. The rear end 13' need not be hexagonal, it may be trained to suit the type of drill, for example by splining, some other polygonal section or a thread. The tool shank 10, which is in one piece, extends through the axial bore in the adapter 13, to within the striking range of a percussion element 21 of the hammer drill, which element 21 is guided in a cylinder 24. The end 10" of the shank ]0 projects from the rear end 13' of the adapter 13 and is struck directly by the element 21. Alternatively, however, the shank might end before the rear end of the adapter and might receive its blows from a projection on the percussion element, the projection dipping rhythmically into the adapter.The shank 10, which exhibits axial play, is received along its cylindrical rear portion 10b by the adapter 13. The tool can be coupled to the adapter by means of two diametrically opposed, cylindrical coupling elements 17. The coupling elements 17 each engage both in a respective recess 18 in the tool shank portion lQ and in a recess 19 in the adapter (see Figure 3). The cylindrical surfaces of the coupling elements 17 are in unbroken contact with corresponding internal cylindrical surfaces in the associated recesses 18, 19, but do not interfere with the required axial play between the tool shank 10 and the adapter 13.

For this purpose, the axial dimensions of the two coupling elements 17 are smaller than the axial dimensions of the recesses 19 in the adapter 13 and 8 or the recesses 18 in the tool shank portion 100. In the embodiment illustrated in the drawing, the axial dimensions of the coupling elements 17 are more than double the diameter of that cylindrical portion 10 of the tool shank in the vicinity of the coupling elements 17.Be cause of the length of the cylindrical coupling elements, and because their fit in the bed formed by the recesses 18, 19 is such as to permit relative axial motion of the adapter and shank, these features being combined with an exceptionally long cylindrical guiding surface for the shank along its portion 1 0b, abrasion of the cylindrical surfaces of the tool shank and adapter is almost completely eliminated, especially in the coupling zone.

The auger flights 12 are locked axially at the rear by a screw-threaded sleeve 14, which meshes with the adapter 13 and, by means of an inward facing flange 14', prevents the tool from dropping out axially by limiting axial movement of the coupling elements 17. A resilient O-ring 15 and a metal ring 16 are mounted between the flange 14' and the end faces of the coupling elements 17. The resilient ring 15, protected by the metal ring 16, damps the rhythmic blows from the axially abutting coupling elements, which are completely embraced by the adapter 13. The simple but robust coupling between the tool and adapted is effected as follows: after mounting of the auger flights 12 on the tool shank, the screw-threaded sleeve 14 is slid on to the shank until it abuts on the flights.The two coupling elements 17 are then placed in their recesses 18, 19, and the adapter is placed over them and screwed into the threaded sleeve. The coupling design described ensures that the end face of the threaded sleeve continues to bear on the flights after screwing and that it locates them axially with only slight axial clearance.

An annular shoulder 20 formed where the shank portion 10e merges with the shank portion 1 0b which is of smaller diameter than the conical shank portion 10d limits the axial clearance between the tool and adapter in one direction and also absorbs the drilling pressure.

In the embodiment illustrated the flights 12 bear on the drill bit 11 of the tool by way of a projection 12' to transmit the torque. In many cases, however, it may be convenient to ensure transmission of the torque from the tool to the flights by means of their contact with the rotating sleeve 14 or the rotating adapter 13.

In conrast to the embodiment illustrated, in which the tool is in one piece comprising the drill bit and shank with the auger flights 12 added on, the tool may alternatively be in one piece comprising the drill bit, tool shank and auger flights. A further alternative, however, is that the drill bit may be mounted on a one-piece tool shank and flights.

A retaining clip 27 embracing a tapered neck on the adapter prevents the adapter from dropping out of the tool socket. A cup seal 28 bears by way of an internal flange, with limited initial tension, on the cylindrical surface of the adapter and is mounted slideably and with axial clearance, by means of another internal flange or an annular sealing lip, on the tool socket 22 or a housing portion 25, which is adjoined by another housing portion 26 of the hammer drill.

WHAT WE CLAIM IS TO: 1. A combination of a hammer drill or rotary hammer drill having a percussion element and a tool socket, a tool, a plug-in adapter and a coupling means, the tool having a shank, the plug-in adapter being adapted to be received by the tool socket, wherein the adapter has a continuous axial bore in which the tool is coupled by the coupling means which comprises at least one coupling element engaging both in a re cess in the tool shank and in a recess in the adapter bore, so that the tool shank extends to within striking range of the percussion element of the hammer drill or rotary hammer drill and is adapted to be struck directly by the percussion element.

2. A combination as claimed in claim 1, in which the end of the tool shank which is to be struck by the percussion element projects from the adapter.

3. A combination as claimed in claim 1 or 2, in which the dimension of the coupling element in the direction of the axis of the axial bore is smaller than the dimension of the recess in the adapter in the direction of the axis of the axial bore and/or the dimension of the recess in the tool shank in the direction of the axis of the axial bore, and the coupled tool is movable axially in the adapter.

4. A combination as claimed in any of the preceding claims, in which the dimension of the coupling element in the direction of the axis of the axial bore is at least twice the diameter of the tool shank in the vicinity of the coupling element.

5. A combination as claimed in any of the preceding claims, in which the tool is in one piece comprising a drill bit and tool shank.

6. A combination as claimed in claim 5, in which the tool is one piece comprising a drill bit, tool shank and auger flights.

7. A combination as claimed in any of claims 1 to 4, in which the tool comprises a bit which is detachable from and movable on the tool shank.

8. A combination as claimed in any of claims 1 to 5, or claim 7 in which the tool shank is embraced by loosely mountable auger flights which are axially located by the drill bit and, directly or indirectly, by the adapter.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. cause of the length of the cylindrical coupling elements, and because their fit in the bed formed by the recesses 18, 19 is such as to permit relative axial motion of the adapter and shank, these features being combined with an exceptionally long cylindrical guiding surface for the shank along its portion 1 0b, abrasion of the cylindrical surfaces of the tool shank and adapter is almost completely eliminated, especially in the coupling zone. The auger flights 12 are locked axially at the rear by a screw-threaded sleeve 14, which meshes with the adapter 13 and, by means of an inward facing flange 14', prevents the tool from dropping out axially by limiting axial movement of the coupling elements 17. A resilient O-ring 15 and a metal ring 16 are mounted between the flange 14' and the end faces of the coupling elements 17. The resilient ring 15, protected by the metal ring 16, damps the rhythmic blows from the axially abutting coupling elements, which are completely embraced by the adapter 13. The simple but robust coupling between the tool and adapted is effected as follows: after mounting of the auger flights 12 on the tool shank, the screw-threaded sleeve 14 is slid on to the shank until it abuts on the flights.The two coupling elements 17 are then placed in their recesses 18, 19, and the adapter is placed over them and screwed into the threaded sleeve. The coupling design described ensures that the end face of the threaded sleeve continues to bear on the flights after screwing and that it locates them axially with only slight axial clearance. An annular shoulder 20 formed where the shank portion 10e merges with the shank portion 1 0b which is of smaller diameter than the conical shank portion 10d limits the axial clearance between the tool and adapter in one direction and also absorbs the drilling pressure. In the embodiment illustrated the flights 12 bear on the drill bit 11 of the tool by way of a projection 12' to transmit the torque. In many cases, however, it may be convenient to ensure transmission of the torque from the tool to the flights by means of their contact with the rotating sleeve 14 or the rotating adapter 13. In conrast to the embodiment illustrated, in which the tool is in one piece comprising the drill bit and shank with the auger flights 12 added on, the tool may alternatively be in one piece comprising the drill bit, tool shank and auger flights. A further alternative, however, is that the drill bit may be mounted on a one-piece tool shank and flights. A retaining clip 27 embracing a tapered neck on the adapter prevents the adapter from dropping out of the tool socket. A cup seal 28 bears by way of an internal flange, with limited initial tension, on the cylindrical surface of the adapter and is mounted slideably and with axial clearance, by means of another internal flange or an annular sealing lip, on the tool socket 22 or a housing portion 25, which is adjoined by another housing portion 26 of the hammer drill. WHAT WE CLAIM IS TO:

1. A combination of a hammer drill or rotary hammer drill having a percussion element and a tool socket, a tool, a plug-in adapter and a coupling means, the tool having a shank, the plug-in adapter being adapted to be received by the tool socket, wherein the adapter has a continuous axial bore in which the tool is coupled by the coupling means which comprises at least one coupling element engaging both in a re cess in the tool shank and in a recess in the adapter bore, so that the tool shank extends to within striking range of the percussion element of the hammer drill or rotary hammer drill and is adapted to be struck directly by the percussion element.

9. A combination as claimed in claim 8,

in which the auger flights bear on a screwthreaded sleeve or the adapter for transmission of torque from the adapter to the auger flights.

10. A combination as claimed in claim 8 or 9, in which the auger flights are axially located at the rear by a screw-threaded sleeve which is in screwed engagement with the adapter and which by means of an internal flange prevents the tool from dropping out axially.

11. A combination as claimed in claim 10, in which a resilient ring and a metal ring are provided between the internal flange on the screw-threaded sleeve and the end face of the locking element.

12. A combination as claimed in any of the preceding claims, in which the coupling element engaging in the recess in the adapter is completely embraced by the adapter.

13. A combination as claimed in any of the preceding claims, in which the tool shank has an annular shoulder which limits the axial clearance between the tool and the adapter and transmits the drilling pressure.

14. A combination as claimed in any of the preceding claims, in which the coupling element is cylindrical.

15. A combination as claimed in any of the preceding claims, in which the coupling element transmits torque from the adapter to the tool.

16. A combination as claimed in any of the preceding claims, in which there are provided two coupling elements.

17. A combination of a hammer drill or rotary hammer drill and a tool, a plug-in adapter and a coupling means substantially as hereinbefore described with reference to the accompanying drawing.