GB2121716A - Hydraulic reciprocating tools - Google Patents

Abstract

The tool comprises a robust housing assembly (1) in which is mounted a manually activated flow control valve (3) and a hydraulic drive motor (11), the motor being drivably connected to an output shaft assembly (14) including a resiliently biased reciprocating member (15, 16, 30) providing a chisel (5). The member (15, 16, 30) is caused to reciprocate under the action of a stepped revolving cam arrangement (32). <IMAGE>

Description

SPECIFICATION Hydraulic reciprocating tools This invention relates to hydraulic reciprocating tools in in particular, although not exclusively, to hydraulic reciprocating impact hammers for chipping rock, rust and corrosion or mineral from a working surface in an underground mine.

An object of the present invention is to provide a hydraulic chipping hammer which is reliable, effective and relatively inexpensive.

According to the present invention a hydraulic reciprocating tool comprises a robust housing defining a handle, manual flow control means for controlling feed of pressure fluid to the tool and including a hand grip lever mounted adjacent to the handle, a hydraulic drive motor adapted to be activated by pressure fluid fed via the flow control means and having a rotary output shaft assembly comprising a rotary member mounted for repeated reciprocal axial motion with respect to the axis of rotation of the shaft assembly, the rotary member being resiliently biassed in one direction of axial motion, a stepped revolving cam arrangement which, in use, upon rotation of the shaft assembly by the drive motor is adapted repeatedly to urge the rotary member axially against the resilient bias and which upon the rotary component being urged axially for a preselected distance releases the rotary component allowing the component to move axially under the action of the resilient bias, and a tool component mounted for axial movement towards a position at which it is capable of being struck by the released rotary member.

Preferably, the tool component comprises a chisel having longitudinally extending slots engaged by bearing elements.

Preferably, the shaft assembly comprises a stub shaft extending from the drive motor and a reciprocally mounted shaft which is arranged co-axial with the stub shaft and which is constituted by the rotary member.

Conveniently, the stub shaft and the rotary member are drivably connected by a sleeve.

Advantageously, the sleeve and the rotary member are provided with abutments, spring mounted between the abutments providing said resilient bias for the rotary member.

Preferably, the rotary member comprises a hammer head for engagement with the tool component.

Advantageously, the stepped revolving cam arrangement comprises a rotary stepped cam component and a co-operating non-stay stepped cam component.

By way of example, one embodiment of the present invention now will be described with reference to the accompanying drawings, in which: Figure 1 is a longitudinal sectional view taken through a chipping hammer constructed in accordance with the present invention; Figure 2 is a cross-sectional view taken along line A-A of Fig. 1; and Figure 3 is a diagram indicating the development of a stepped cam profile provided on a detail of Fig. 1, the development being shown on an enlarged scale.

Figs. 1 and 2 show the chipping hammer to comprise a generally elongated robust housing assembly 1 defining a handle 2 adjacent to one end. A hydraulic flow control spool valve 3 is provided for controlling feed of pressure fluid to the hammer from supply lines connected to input and output connectors 4 and 5, respectively. Movement of the spool 6 is controlled by a pivotally mounted hand grip lever 7 situated adjacent to the handle 2 for ease of operation. The lever is moved into an operational position feeding pressure fluid along passages 8 to a hydraulic drive motor 11 by an operator squeezing the lever towards the handle against the action of a spring 9. The spring 9 returns the lever and thereby to spool 6 to an inoperative position upon the operator releasing the lever.A pressure reducing throttle valve 10 is provided in the passages 8 prior to the pressure fluid reaching the drive motor 11 input connector 1 2. The valve 10 is provided to control the speed of the drive motor 11.

An output stub shaft 1 3 from the motor 11 constitutes part of an output shaft assembly 1 4 comprising a rotary member 1 5 in the form of a reciprocating shaft member mounted co-axially with the stub shaft and having a flanged abutment 1 6 for engagement by one end of a spring 1 7. The other end of the spring 1 7 engages a flanged abutment 1 8 provided on a sleeve 1 9 drivably connecting the stub shaft and the shaft member. The two shafts are provided with keys 20, 21, respectively, engaging in keyways 22 extending longitudinally along the sleeve. As the shaft member reciprocates the keys 21 slide to and fro along the longitudinally extending slideways.

A hammer head 30 fixedly secured to the flanged abutment 1 6 is slideably supported for reciprocal motion in a bearing block 31. A stepped, revolving cam arrangement 32 located between the flanged abutment 1 6 and the bearing block 31 comprises a rotary stepped cam component 33 and a co-operating non-rotary stepped cam component 34.

Fig. 3 illustrates the development of the two co-operating stepped cam profiles on an enlarged scale. From Fig. 3 it will be appreciated that as the rotary cam component moves to the left as indicated by arrow X in the drawing and upon the pairs of inclined surfaces 36 and 37 engaging the rotating cam component is urged to move upwards as seen in Fig. 3 ie longitudinally as seen in Fig. 1 against the action of the resilient bias pro vided by spring 1 7 longitudinal movement continues for a preselected distance determined by the dimensions of the cam profiles.

Upon further rotation of the rotary cam component the two components engage along short flat surfaces 38, 39 with the rotary cam component briefly maintained at its preselected maximum longitudinal displacement.

Upon the stepped portions 40 and 41 on the two cam profiles being brought into alignment the rotary cam component is released to move rapidly longitudinally under the action of its spring bias such that the hammer head impacts on a withdrawn chisel 50 extending from the tool housing assembly. The chisel comprises a blade 51 and a shaft 52 having two longitudinally extending grooves 53 engaged by two balls 54 accommodated in cross bores provided in a bearing block 55 constituting the end of the housing assembly.

The block 55 provides support for the shaft of the chisel permitting the shaft to reciprocate longitudinally between fully extended position after impact by the hammer head and a fully withdrawn position in which the end of the shaft is capable of being contacted by the reciprocating hammer head. In use, the operator holds the tool with the chisel blade in contact with the material to be broken or cleared from a working face in an underground mine. In this position the reaction of the rock or mineral urges the chisel into a withdrawn position for impact by the hammer head. If the chisel is not held in contact with a working surface then the chisel tends to remain in an extended mode away from contact with the reciprocating hammer head.

Fig. 3 shows the cam profile developments over 360 . Each cam component comprises two similar cam profiles. Thus two impacts are delivered by the hammer head for each revolution of the drive motor. Fig. 3 also illustrates that with this particular embodiment of cam profiles, the aforementioned short flat surfaces 38, 39 extend for 13 . The cam profiles are provided with relatively long flat profiles 56, 57 at the bases of the inclined surfaces which extend for 82 and provide a dwell period after each impact. The length of each dwell period is determined by the angular extent of the relatively long and short flat surfaces. In the example illustrated in Fig. 3 each dwell period lasts over an angle of 69 .

The speed of motor 11 can be regulated by adjusting the setting of the throttle valve 10 so varying the frequency of vibration to suit working on different materials. An added benefit of speed control is that the amplitude of vibration of the chisel is also altered, again making it adjustable to suit different working materials.

In other embodiments the angular extents of the flat and inclined surfaces can be varied.

Also the angle of the inclined surfaces might be varied to increase or to reduce the impact blow as desired.

Claims (8)

1. A hydraulic reciprocating tool comprising a robust housing defining a handle, manual flow control means for controlling feed of pressure fluid to the tool and including a hand grip lever mounted adjacent to the handle, a hydraulic drive motor adapted to be activated by pressure fluid fed via the flow control means and having a rotary output shaft assembly comprising a rotary member mounted for repeated reciprocal axial motion with respect to the axis of rotation of the shaft assembly, the rotary member being resiliently biassed in one direction of axial motion, a stepped revolving cam arrangement which, in use, upon rotation of the shaft assembly by the drive motor is adapted repeatedly to urge the rotary member axially against the resilient bias and which upon the rotary component being urged axially for a preselected distance releases the rotary component allowing the component to move axially under the action of the resilient bias, and a tool component mounted for axial movement towards a position in which it is capable of being struck by the released rotary member.

2. A tool as claimed in claim 1, in which the tool component comprises a chisel having longitudinally extending slots engaged by bearing elements.

3. A tool as claimed in claim 1 or 2, in which the shaft assembly comprises a stub shaft extending from the drive motor and a reciprocally mounted shaft which is arranged co-axial with the stub shaft and which is constituted by the rotary member.

4. A tool as claimed in claim 3, in which the stub shaft and the rotary member are drivably connected by a sleeve.

5. A tool as claimed in claim 4, in which the sleeve and the rotary member are provided with abutments, spring mounted between the abutments providing said resilient bias for the rotary member.

6. A tool as claimed in any one of the preceding claims, in which the rotary member comprises a hammer head for engagement with the tool component.

7. A tool as claimed in any one of the preceding claims, in which the stepped revolving cam arrangement comprises a rotary stepped cam component and a co-operating non-rotary stepped cam component.

8. A hydraulic reciprocating tool substantially as described herein and as shown in the accompanying drawings.