GB1593577A - Percussive drilling tool - Google Patents

Description

(54) A PERCUSSIVE DRILLING TOOL (71) We, TORQUE TENSION LIMITED, a British company, of Clayland Avenue, Worksop, Nottinghamshire S81 7BQ, 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::- According to the invention, there is provided a tool for use in percussive drilling comprising a chuck for holding a drill steel of a drilling bit, a hydraulic motor mechanically coupled to the chuck for rotating it, a hydraulically-operated reciprocating mechanism for striking the drill steel either directly or indirectly in a direction which is substantially parallel to the axis of the chuck when the drill steel is held by the chuck, and a flow control valve, the tool being such that fluid at pressure entering the tool is divided between the hydraulic motor, which has priority, and the fluid flow through which is controlled in consequence of the provision of said valve, and the reciprocating mechanism which receives the remainder of the fluid entering the tool.

It would be possible to have a hydraulic motor, for rotating the chuck, connected by two hoses (feed and return) to a source of fluid at pressure, and a reciprocating mechanism, for striking the drill steel, connected by another two hoses (feed and return) to the same source, there being no flow control valve. When the present invention is used instead of this. arrangement, the four hoses can be reduced to two hoses.

Thus the tool may have an entry port for connection by a hose to a source of fluid at pressure and an exit port for connection by a hose to said source, the flow control valve being interposed between one of these ports and the hydraulic motor and there being direct connections between the other port and the hydraulic motor and between both ports and the reciprocating mechanism. Preferably, the flow control valve is interposed between the exit port and the exhaust side of the hydraulic motor, so that heat imparted to the fluid by the flow control valve is not transferred to the hydraulic motor, and moreover is carried directly out of the tool by the hydraulic fluid.

The tool may be a hand-held tool, i.e. one which can be operated whilst supported only by the hands of the operator.

An example in accordance with the invention is described below with reference to the accompanying drawing, in which: Figure 1 shows a side view, partly in section taken as indicated by the arrows I in Figure 2, of a tool for use in percussive drilling; and Figure 2 shows an end view, partly in section taken as indicated by the arrow II in Figure 1, of the same tool.

The illustrated tool comprises a casing formed of parts 11, 12, 13 and 14 secured together, of which the parts 13 and 14 have bores which are closed by plugs 15. Within the casing part 11 is a chuck 1 which is mounted for rotation in a bearing sleeve 16 and carries a gear wheel 2. This gear wheel meshes with a smaller gear wheel 17 carried by one end of a lay shaft 3, which at its other end is secured to the rotor of a hydraulic motor 7, whereby the chuck is mechanically coupled to the hydraulic motor for rotation by the motor about the axis 18, which is the axis of the chuck and the axis of a drill steel of a drilling bit (for example for rock drilling) when the drill steel is held by the chuck and extends out of the tool through an opening 19.Within the casing part 13 is a reciprocating mechanism 10 which is not shown in detail nor described here because its construction forms no part of the present invention and is in principle known per se. A typical example of such a mechanism is illustrated and described in British Patent Specification No. 960,366. The mechanism 1strikes the drill steel when the latter is in the chuck by means of a piston 20 having an annular end face 21 which strikes the drill steel directly in a direction which is parallel to the axis 18, when fluid at sufficient pressure is supplied to the reciprocating mechanism via a duct 22. In an alternative embodiment, not shown, the reciprocating mechanism could strike the drill steel indirectly.A hose (not shown) connects the pressure side of a pump (not shown) to an entry port 5 of the tool and another hose (not shown) connects an exit port 4 of the tool to a sump from which the pump draws fluid for powering the hydraulic motor 7 and the reciprocating mechanism 10. The entry port 5 is directly connected to the reciprocating mechanism via the duct 22 and to the pressure side of the hydraulic motor via a duct 9, a duct 23 and a passage 8A.The exit port 4 is directly connected to the reciprocating mechanism 10 via a duct (not shown) and is connected to the exhaust side of the hydraulic motor via a passsage 8B, a duct 24 and flow control valve 6, of which several makes are widely commercially available and suitable for use as the valve The fluid at pressure entering the port 5 of the tool is divided between the hydraulic motor 7, which has priority of operation, because of its relatively low resistance to flow, and always rotates the chuck 1, and the reciprocating mechanism 10 which receives the remainder of the fluid entering the port 5 and reciprocates the drill steel if the pressure of the fluid it receives is high enough.The valve 6 controls the priority flow through the hydraulic motor 7 so that flow entering the entry port 5 which is surplus to the requirement of the hydraulic motor 7 can flow to the reciprocating mechanism 10.

The tool described above has handles (not shown) whereby an operator can operate the tool whilst supporting it only by his hands.

Flushing water is supplied to the hollow drill steel and thence to the drilling bit via a connection 25 and a duct 26 which extends through the reciprocating mechanism 10 and through the centre of the piston 20.

WHAT WE CLAIM IS:- 1. A tool for use in percussive drilling comprising a chuck for holding a drill steel of a drilling bit, a hydraulic motor mechanically coupled to the chuck for rotating it, a hydraulically-operated reciprocating mechanism for striking the drill steel either directly or indirectly in a direction which is substantially parallel to the axis of the chuck when the drill steel is held by the chuck, and a flow control valve, the tool being such that fluid at pressure entering the tool is divided between the hydraulic motor, which has priority, and the fluid flow through which is controlled in consequence of the provision of said valve, and the reciprocating mechanism which receives the remainder of the fluid entering the tool.

2. A tool according to claim 1 having an entry port for connection by a hose to a source of fluid at pressure and an exit port for connection by a hose to said source, the flow control valve being interposed between one of these ports and the hydraulic motor and there being direct connections between the other port and the hydraulic motor and between both ports and the reciprocating mechanism.

3. A tool according to claim 2 in which the flow control valve is interposed between the exit port and the exhaust side of the hydraulic motor.

4. A tool according to any preceding claim which can be operated whilst supported only by the hands of the operator.

5. A hand-held tool for use in percussive drilling, substantially as described hereinbefore with reference to the accompanying drawing.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. of a pump (not shown) to an entry port 5 of the tool and another hose (not shown) connects an exit port 4 of the tool to a sump from which the pump draws fluid for powering the hydraulic motor 7 and the reciprocating mechanism 10. The entry port 5 is directly connected to the reciprocating mechanism via the duct 22 and to the pressure side of the hydraulic motor via a duct 9, a duct 23 and a passage 8A.The exit port 4 is directly connected to the reciprocating mechanism 10 via a duct (not shown) and is connected to the exhaust side of the hydraulic motor via a passsage 8B, a duct 24 and flow control valve 6, of which several makes are widely commercially available and suitable for use as the valve The fluid at pressure entering the port 5 of the tool is divided between the hydraulic motor 7, which has priority of operation, because of its relatively low resistance to flow, and always rotates the chuck 1, and the reciprocating mechanism 10 which receives the remainder of the fluid entering the port 5 and reciprocates the drill steel if the pressure of the fluid it receives is high enough.The valve 6 controls the priority flow through the hydraulic motor 7 so that flow entering the entry port 5 which is surplus to the requirement of the hydraulic motor 7 can flow to the reciprocating mechanism 10. The tool described above has handles (not shown) whereby an operator can operate the tool whilst supporting it only by his hands. Flushing water is supplied to the hollow drill steel and thence to the drilling bit via a connection 25 and a duct 26 which extends through the reciprocating mechanism 10 and through the centre of the piston 20. WHAT WE CLAIM IS:-

1. A tool for use in percussive drilling comprising a chuck for holding a drill steel of a drilling bit, a hydraulic motor mechanically coupled to the chuck for rotating it, a hydraulically-operated reciprocating mechanism for striking the drill steel either directly or indirectly in a direction which is substantially parallel to the axis of the chuck when the drill steel is held by the chuck, and a flow control valve, the tool being such that fluid at pressure entering the tool is divided between the hydraulic motor, which has priority, and the fluid flow through which is controlled in consequence of the provision of said valve, and the reciprocating mechanism which receives the remainder of the fluid entering the tool.

2. A tool according to claim 1 having an entry port for connection by a hose to a source of fluid at pressure and an exit port for connection by a hose to said source, the flow control valve being interposed between one of these ports and the hydraulic motor and there being direct connections between the other port and the hydraulic motor and between both ports and the reciprocating mechanism.

3. A tool according to claim 2 in which the flow control valve is interposed between the exit port and the exhaust side of the hydraulic motor.

4. A tool according to any preceding claim which can be operated whilst supported only by the hands of the operator.

5. A hand-held tool for use in percussive drilling, substantially as described hereinbefore with reference to the accompanying drawing.