ROCK BREAKING APPARATUS

This invention relates generally to apparatus for working materials, such as reducing rock by fracturing it into small sections suitable for handling, and particularly to a tool assembly which can be used in that apparatus.

One such type of apparatus and tool assembly therefor has been disclosed in Applicant's earlier Australian patent 522,890. That tool assembly includes a tool mounting having a tubular fixed sleeve, and a tubular movable sleeve mounted for telescopic movement relative to the fixed sleeve in a working direction and an opposite return direction; and a tool mounted on the movable sleeve for movement relative thereto in the working and return directions, and having limit means arranged to abut the movable sleeve to limit that movement of the tool relative to the movable sleeve to between a too) operative position and a tool operated position, the tool during a working stroke being engaged with material to be worked and moved under action of a working force applied by a striker block from the operative position to the operated position and thereafter in unison with the movable sleeve in the working direction relative to the fixed sleeve thereby to work the material.

Whilst the apparatus of Applicant's prior patent is generally satisfactory in operation, it has been found that, if the striker block is operated to move the tool from its operative to its operated position during a rock breaking operation, and particularly when the tool is not properly positioned on the rock or the rock is easily fractured, the striker block tends to move the tool to its operated position with such a working force that potentially damaging stresses and vibrations are transmitted through the apparatus. This is the result of absorption by the tool mounting and apparatus of the working forces once the tool has reached its operated position and further movement thereof is resisted by the limit means and tool mounting.

It is an object of the present invention to avoid that disadvantage of the above type of apparatus and tool assembly through the provision of an alternative simple tool assembly.

French Patent Specification No. 1,479,556 discloses a percussive apparatus having a fixed section and a movable section on which the tool itself is mounted. Transmission of damaging stresses to the apparatus during operation is minimised by a biasing spring located between the fixed section and the movable section. However, the apparatus is not otherwise of the basic type to which the present invention relates. In particular, the tool itself is not capable of limited movement relatively to the movable section of the apparatus.

According to the present invention, a tool assembly of the kind described above in relation to Australian Patent No. 522,890 is characterised in that a plurality of resilient biasing members are stacked in seriatim so as to extend between opposed abutment faces on the fixed and movable sleeves whereupon movement of the movable sleeve in the working direction compresses the biasing members between the fixed sleeve and the movable sleeve to absorb applied tool working forces transferred from the tool to the movable sleeve when the limit means abuts the movable sleeve as the tool reaches the tool operated position during a working stroke, compression of the biasing members providing a restoring force to the movable sleeve for returning the movable sleeve in the return direction upon conclusion of the working stroke of the tool.

The movable sleeve may have a nose portion projecting out from the fixed sleeve which moves away from the fixed sleeve during movement of the movable sleeve in the working direction and moves toward the fixed sleeve during movement of the movable sleeve in the return direction.

The fixed sleeve may be spaced apart outwardly from the movable sleeve, the fixed sleeve having a bearing element mounted thereon and located between the spaced apart sleeves so as to slidingly engage the movable sleeve, the movable sleeve having a bearing element mounted thereon and located between the spaced apart sleeves so as to slidingly engage the fixed sleeve, the movable sleeve thereby being slidably mounted relative to the fixed sleeve.

Said opposed abutment faces may be provided one each on a respective bearing element.

In any of the above arrangements each resilient biasing member may comprise a biasing ring composed of an elastomeric material extending peripherally about the movable sleeve. The cross-sectional configuration of successive biasing rings may alternate between circular and rectangular.

In any of the above arrangements where the movable sleeve has a nose portion, the movable sleeve may include a tool support removably mounting the tool at the nose portion of the movable sleeve, the tool support having a bore extending therethrough in which the tool is slidably mounted for movement between the operative and operated positions thereof, and wherein the limit means abuts the tool support to limit movement of the tool relative to the movable sleeve.

In this case the tool support may include a carrier plate removably mounted on the nose portion and defining an insert aperture extending therethrough, and an abutment plate removably mounted in the insert aperture and defining the bore in which the tool is slidably mounted, peripheral faces of the carrier plate defining the insert aperture, the abutment plate being correspondingly shaped so as to frictionally interengage thereby to retain the abutment plate within the insert aperture during working strokes of the tool.

Preferably, the peripheral faces of the carrier plate correspondingly converge in the working direction. The abutment plate may comprise at least two sections which are separable to permit removal of the tool from the bore.

The tool support may further include a backing plate at least substantially overlying the carrier plate and the abutment plate to assist in retaining the abutment plate in the insert aperture.

In any of the above arrangements the tool may have an elongated body longitudinally movable in the working and return directions, and a head at one end of the tool body with a working tip which is engageable with the material to be worked, and the limit means may include a pair of spaced apart limit collars integral with the tool body and each arranged to abut the movable sleeve to limit movement of the tool in a respective working direction and return direction.

A limit stop may be provided to limit return movement of the movable sleeve and, with the biasing members, to assist in positively locating the movable sleeve relative to the fixed sleeve.

The present invention also provides apparatus for working a material, such as rock as defined in claim 15.

The following description refers in more detail to the various features of the apparatus and tool assembly of the present invention. To facilitate an understanding of the invention, reference is made to the accompanying drawings where these features are illustrated in a specified preferred embodiment. It is to be understood that the features of the invention are not limited to the specific embodiment as illustrated in the drawings.

In the drawings:

• Fig. 1 is a side elevation partly in section of apparatus with tool assembly according to a preferred embodiment of the present invention;
• Fig. 2 is a detailed side elevation partly in section of the tool assembly of Fig. 1, showing the assembly prior to a working stroke of the tool;
• Fig. 3 is the tool assembly of Fig. 2 during a working stroke of the tool; and
• Fig. 4 is the tool assembly of Fig. 2 at the conclusion of the working stroke of the tool.

Referring initially to Fig. 1 there is generally illustrated apparatus 1, for breaking rock piece R. Apparatus 1, includes apparatus frame 2, supporting tool actuating means 3, and tool assembly 4, actuation of actuating means 3, operating tool assembly 4, for a spalling operation of rock piece R.

Apparatus frame 2, includes upper and lower frame members 5, 6, secured together such as by one or more struts 7. Each of upper and lower frame members 5, 6, is provided with mounting aperture 8, by which apparatus 1, can be mounted on a vehicle (not shown), such as a front end loader tractor, for transportation and manipulation during use of apparatus 1.

Frame 2, also includes tubular, open ended guide column 9, rigidly secured to frame members 5, 6, such a by welding thereto. Guide column 9, has longitudinal axis 10, which during operation of apparatus 1, extends generally vertically as will become more apparent hereinafter.

Actuating means 3, includes drive motor 11, securely mounted on upper frame member 5, drivingly connected to drum winch 12, through a suitable clutch (not shown) for engaging and disengaging drum winch 12, from drive motor 11. Drive motor 11, may be of any suitable construction and in that regard may be driven by pressurised hydraulic fluid supplied by the transportation vehicle (not shown). Actuating means 3, also includes striker block 13, located within guide column 9, for sliding movement therealong, striker block 13, being connected to drum winch 12, for movement thereby through connecting cable 14, which extends from drum winch 12, over guide pulley 15, and into guide column 9, to striker block 13. Striker block 13, includes connection bracket 16, to facilitate cable connection thereto.

Tool assembly 4, is illustrated in more detail in Figs. 2 to 4, and includes elongated tool mounting 17, secured to and generally forming a lower coextension to tubular guide column 9. Tool mounting 17, has fixed section 18, rigidly mounted on column 9, such as by welding thereto, and movable section 19, mounted in fixed section 18, for telescopic sliding movement relative thereto in a working direction D_w, and an opposite return direction D_R, along longitudinal axis 10.

Fixed section 18, and movable section 19, each include a respective open ended cylindrical sleeve 20, sized so as to be spaced apart with sleeve 20, of fixed section 18, being positioned outwardly of and forming shoulder 21, with guide column 9, whilst sleeve 20, of movable section 19, forms a coextension of guide column 9. As a result annular space 22, is defined between fixed section 18, and movable section 19. Sleeve 20, of movable section 19, is longer than sleeve 20, of fixed section 18, and has nose portion 23, projecting out of fixed section 18, to terminate in open end 24, spaced from fixed section 18.

Each of fixed section 18, and movable section 19, also has a bearing ring 25, secured to a respective sleeve 20, in spaced apart relationship and slidably engaging the other sleeve 20, so that movable section 19, is guided during sliding movement relative to fixed section 18. Bearing rings 25, close annular space 22.

Each bearing ring 25, may be secured to respective sleeve 20, in any suitable manner. In that regard, one bearing ring 25, may be permanently secured to sleeve 20, of movable section 19, such as by welding thereto, whilst the other bearing ring 25, may be removably secured to sleeve 20, of fixed section 18, such as by a plurality of fastening elements 26 (only one of which is illustrated). Each one bearing ring 25, includes a unitary or fabricated bearing block 27, slightly spaced from that sleeve 20, which bearing ring 25, is to engage, and bearing pad 28, supported within bearing block 27, and actually engaging the other sleeve 20.

Positioned within space 22, is a plurality of resilient biasing rings 29, extending about sleeve 20, of movable section 19, and stacked between opposed abutment faces 30, conveniently provided by bearing blocks 27, of bearing rings 25. Biasing rings 29, alternate between circular and rectangular cross-sectional configurations and are sized so as to closely fit between sleeves 20. Each biasing ring 29, is composed of an elastomeric material, such as rubber.

Tool mounting 17, further includes limit stop 31, which acts to limit sliding movement of movable section 19, in return direction D_R. Limit stop 31, also acts with resilient biasing rings 29, to positively locate movable section 19, relative to fixed section 18. Limit stop 31, includes buffer ring 32, composed of an elastomeric material such as rubber mounted on bearing ring 25, of movable section 19, and arranged to abut shoulder 21, to limit movement of movable section 19. Buffer ring 31, acts to absorb any shock forces which may occur as a result of engagement with shoulder 21.

Tool assembly 4, also includes tool support 33, removably mounting tool 34, on nose portion 23, of movable section 19. Tool support 33, includes support flange 35, extending transversely of longitudinal axis 10, and rigidly secured adjacent open end 24, of nose portion 23, such as by welding thereto. Strengthening webs 36, assist in securing flange 35, to nose portion 23.

Tool support 33, also includes carrier plate 37, removably mounted on support flange 35, by a plurality of bolt fasteners 38 (only one of which is illustrated) spaced about support flange 35, and carrier plate 37. Carrier plate 37, has insert aperture 39, extending therethrough coaxially of longitudinal axis 10, and defined by peripheral face 40.

Mounted within insert aperture 39, is abutment plate 41, having peripheral face 42. Abutment plate 41, and carrier plate 37, lie coplanar of each other, with abutment plate 41, being supported within insert aperture 39, by frictional engagement between peripheral faces 40, and 42. To that end, faces 40, and 42, correspondingly converge across carrier plate 37, and abutment plate 41, respectively in working direction D_w. The angle of that convergence changes twice so that those faces 40, and 42, are of a stepped nature. In this way, abutment plate 41, is supported by carrier plate 37, and prevented from moving out of insert aperture 39, in working direction D_w, during operation of apparatus 1.

To prevent abutment plate 41, from accidentally coming out of insert aperture 39, in return direction D_R, tool support 33, is further provided with backing plate 43, generally overlying carrier plate 37, and abutment plate 41, and sandwiched between support flange 35, and carrier plate 37. Thus, abutment plate 41, is positively held within insert aperture 39, during apparatus 1, operation but can be relatively easily removed therefrom upon dismantling of tool support 33.

Tool 34, is mounted in bore 44, extending through abutment plate 41, and clearance aperture 45, extending through backing plate 43, bore 44, and aperture 45, lying coaxially of longitudinal axis 10. Abutment plate 41, may be split into a plurality of sections (not shown) so as to allow ready removal of tool 34, from bore 44, such as for replacement of tool 34, upon dismantling of tool support 33.

Tool 34, has cylindrical elongated body 46, slidably mounted within bore 44, and head 47, at one end of body 46, with a working tip which is engageable with a surface S, of rock piece R, during a spalling operation. Tool 34, also has striking face 48, formed at the other end of the tool body for striking with striker block 13, during operation of apparatus 1.

Tool 34, is freely slidable longitudinally within bore 44, but is limited as to the extent of that movement to between an operative position as illustrated in Fig. 2 and an operated position as illustrated in Figs. 3 and 4. Limitation of that movement is achieved by means of a pair of spaced apart limit collars 49, and 50, each of which abut abutment plate 41, when tool 34, is respectively in its operative and operated positions. Limit collars 49, and 50, may be formed integral with tool body 46. As illustrated clearance aperture 45, is sized relative to limit collar 50, to allow clearance of collar 50, during movement of tool 34.

In operating the above described preferred embodiment of apparatus 1, the apparatus is initially mounted on to a vehicle of a preferred type and hydraulic drive motor 11, connected to the vehicle's hydraulic system. Apparatus 1, is then manoeuvred until guide column 9, and tool assembly 4, are positioned immediately above rock piece R, to be broken. Apparatus frame 2, is then lowered until head 47, of tool 34, rests directly on rock piece R, and tool 34, is urged into its operative position as illustrated in Fig. 2.

Striker block 13, is then completely raised within guide column 9, by drive motor 11, and upon operation of the clutch between motor 11, and drum winch 12, allowed to fall under action of gravity. In so falling, striker block 13, passes along guide column 9, and then along sleeve 20, of movable section 19, until it strikes striking face 48, of tool 34, and apply tool working forces thereto. In striking striking face 48, tool 34, is driven to its operated position and in doing so breaks rock piece R, as illustrated in Fig. 3.

As limit collar 50, of tool 34, engages abutment plate 41, movable section 19, is thereafter caused to move in unison with tool 34, for any further movement in the working direction D_w. That movement of movable section 19, is against the bias of resilient biasing rings 29, which in effect act to absorb the tool working forces transferred from limit collar 50, to abutment plate 41, which otherwise would have been transmitted to guide column 9, and frame 2. Movement of movable section 19, causes compression of resilient biasing rings 29, and that in turn causes creation of a restoring force within those rings 29, as illustrated in Fig. 4.

Unitary movement of movable section 19, and tool 34, continues until dissipation of toot working forces applied by striker block 13. Thereafter striker block 13, is disengaged from striking face 48, for raising within guide column 9, and that causes the restoring force within resilient biasing rings 29, to return movable section 19, in the return direction D_R, until buffer ring 32, abut shoulder 21.

The tool assembly of the present invention minimises transmission of potentially damaging stresses and vibrations through the apparatus during operation of that apparatus. As such, the apparatus is less proneto damage so that its useful life may be maximised.

The tool assembly of the present invention and the apparatus incorporating that assembly is relatively simple in construction and operation so that its costs of purchase and maintenance may be minimal.