AU2020203722A1 - An improved pick back flushing spray for shearing drums - Google Patents

Abstract

A pick back flushing spray comprises a nozzle which is configured for engaging a spray body to receive water flow therefrom via an inlet of the nozzle in use. The nozzle has a central bore and at least one helical bore at least partially around the central bore connecting the inlet and an outlet thereof. 8

Description

An improved pick back flushing spray for shearing drums Field of the Invention

[1] This invention relates generally to pick back flushing sprays for shearing drums, such as those used in coal mining.

Background of the Invention

[2] Rotating shearing drums have a plurality of radial pick assemblies for shearing a coal face or the like. Each assembly comprises a hardened radial tool pick (typically 130mm in length and with a tungsten carbide tip) held within a tool holder by a retention pin. A pick back flushing spray directs a conical spray of water to envelop the radial tool pick tip primarily for ignition control, but also dust suppression.

[3] The British Coal, Codes & Rules paper entitled 'The Control of Frictional Ignitions on Shearers' published in November 1993 specifies several requirements to determine whether a pick back flushing spray is suitable for ignition control. The paper refers to pick back flushing sprays on pages 29-32.

[4] With reference to Figure 1, the British Coal requirements for pick back flushing (PBF) sprays suitable for ignition control include that: a. All PBF spray nozzles shall form a solid uniform cone. b. The maximum spray width (W) and length (L) shall be measured on a plane set at the highest point of the steel body of the pick (datum X-X) on Figure 2. c. The leading edge of the spray shall, as a minimum, pass through, and preferably below the base of the carbide tip on the leading edge of the pick - Point A on Figure 2.

d. The length of the spray (L1) behind the pick shall exceed 40mm. e. The width of the spray across the datum X-X at point B shall be greater than twice the maximum width of the steel body of the pick measured across the seat of the carbide tip. f. An ignition control spray supplied within the pressure range of 7 to 19 bar, shall be deemed acceptable when:

Acceptance Criteria: oPO.3>12 Where: a = spray density (L/s/m2)

P = spray nozzle pressure, minimum 7, maximum 19 (bar)

Spray Density:

o= Q x 10615rTWL

Where:

Q = rate of water flow (L/min)

W = maximum spray width (mm)

L = maximum spray length (mm)

[5] An ideal design configuration of a pick back flushing spray is one which meets the

above requirements whilst reducing water wastage.

[6] The present invention seeks to provide an improved pick back flushing spray, which

will overcome or substantially ameliorate at least some of the deficiencies of the prior art,

or to at least provide an alternative.

[7] It is to be understood that, if any prior art information is referred to herein, such

reference does not constitute an admission that the information forms part of the common

general knowledge in the art, in Australia or any other country.

Summary of the Disclosure

[8] With reference to Figure 2, a pick back flushing spray 100 of the prior art comprises

a spray body 101 having an inlet 124 leading via a longitudinal bore 109 to a tangential bore

108 defining an outlet 104 at a distal face thereof.

[9] The tangential bore 109 comprises an entrance 110 within which a nozzle piece 103 is inserted and retained. The nozzle piece 103 comprises a head 110 which seals the

entrance 110. The nozzle piece 103 comprises a central bore 106 coaxially aligned with the

outlet 104.

[10] The nozzle piece 103 comprises an orthogonal inlet 105 leading to the central bore

106 through which a portion of the water flow from the longitudinal bore 109 flows via the longitudinal bore 106 towards the outlet 104.

[11] The remainder of the water flow from the longitudinal bore 109 escapes annularly

around between the sides of the nozzle piece 103 and the interior of the central bore 108.

The nozzle piece 103 comprises swirl vanes 107 which swirl the annular water flow towards

the outlet 104.

[12] We found that the prior art pick back flushing spray 100 is however problematic at

least for the reason that the insertion tolerance of the nozzle piece 103 within the tangential bore 108 introduces variability to the above conical waterjet characteristics which are difficult to control and which may lead to water wastage.

[13] As such, there is provided herein a pick back flushing spray which comprises a nozzle

configured for engaging a spray body to receive water flow therefrom via an inlet of the

nozzle in use.

[14] The nozzle comprises a central bore and at least one interior helical bore at least

partially around the central bore connecting the inlet an and outlet of the nozzle. In a

preferred embodiment, the helical bores comprise double start first and second helical

bores.

[15] In a preferred embodiment the central and helical bores are formed by a 3D printing

process, preferably a metal 3D printing process.

[16] The present arrangement of the nozzle retained within a spray body to eject a cone

of water from the outlet of the nozzle and the interior arrangement of central and helical

bores reduces or at least substantially eliminates the tolerance variability of problems of

prior art pick back flushing spray systems which may allow for fine control of spray cone

characteristics and reduction of manufacturing variability, thereby allowing for water-saving

in use.

[17] Other aspects of the invention are also disclosed.

Brief Description of the Drawings

[18] Notwithstanding any other forms which may fall within the scope of the present

invention, preferred embodiments of the disclosure will now be described, by way of

example only, with reference to the accompanying drawings in which:

[19] Figure 1 shows pick back flushing spray geometry for compliance calculations;

[20] Figure 2 shows a pick back flushing spray in accordance with the prior art;

[21] Figure 3 shows a side transparent view of a nozzle for a pick back flushing spray in

accordance with an embodiment;

[22] Figure 4 shows a cross-sectional view of the nozzle of Figure 3;

[23] Figure 5 shows a spray body for engaging the nozzle of Figure 3 in accordance with

an embodiment;

[24] Figures 6 and 7 provide exemplary embodiments for the novel of Figure 3 and the

spray body of Figure 5 in accordance with an embodiment.

Description of Embodiments

[25] A nozzle 115 is configured for engaging a spray body 113 to receive water flow therefrom.

[26] The spray body 113 is generally longitudinal comprises a longitudinal bore 114 leading from the water inlet 130 to a nozzle retention chamber 122. The nozzle retention chamber 122 may widen at a mouth 123. The nozzle 115 is configured for insertion within the nozzle retention chamber 122.

[27] The nozzle 115 may comprise threading 116 which screws into threading (not shown) of the nozzle retention chamber 122.

[28] The nozzle 115 may comprise a head 124 defining a rearward annular edge 130 which may seal against the corresponding annular edge of the mouth 123. In embodiments, an 0 ring may interface the rearward annular edge 130 and the annular edge of the mouth 123.

[29] The nozzle 115 comprises an inlet 125 to receive water flow from the longitudinal bore 115 via the nozzle retention chamber 122. The nozzle retention chamber 122 may comprise a back off 126 to allow water to flow behind the nozzle 115 into the inlet 125 thereof.

[30] The nozzle 115 may comprise coaxially opposing insertion tool tine engagement apertures 116 which may be engaged by tines of an insertion tool in use to screw the nozzle 115 into the nozzle retention chamber 122.

[31] The nozzle 115 comprises a central bore 119 leading from the inlet 125 to an outlet 131. The nozzle 115 further comprises at least one helical bore 118At least partially around the central bore 119 connecting the inlet 125 and the outlet 131.

[32] In a preferred embodiment, the nozzle 115 comprises a first helical bore 118A and a second helical bore 118B.

[33] With reference to Figure 4, the nozzle 150 may comprise an inlet stage chamber 117 leading from the inlet 125. The inlet stage chamber 117 may have an inlet end face 127 funnelling to the central bore 119 coaxially.

[34] The first and second helical bores 118A, 118 B may lead off tangentially from the interface 127 at oppositely adjacent entrances 121 through the inlet end face 127 either side of the central bore 119. In embodiments, the inlet end face 127 may be substantially frustoconical.

[35] The central bore 118And the helical bores 118 may meet at an outlet stage chamber 120. The outlet stage chamber 120 may have an outlet end face 128 funnelling towards the outlet 131.

[36] The outlet stage chamber 120 may comprise an inlet end face 129. In this regard, the

helical bores 118 may lead in tangentially to intersect the inlet end face 129 at respective

entrances oppositely adjacent the central bore 119. The outlet end face 128 may be

substantially frustoconical. Furthermore, the inlet end face 129 may be planar.

[37] The nozzle 115 is preferably metallic. The nozzle 115 is preferably manufactured by

a metal 3D printing process.

[38] Exemplary dimensions are provided in figures 6 and 7.

[39] In embodiments, the inlet end face 127 comprises an arc of approximately 90. In

embodiments, the outlet interface 128 comprises an arc of approximately 90. Furthermore,

each helical bore 118 may comprise a diameter approximately equal to that of the central

bore 119.

[40] Each helical bore may rotate through 180.

[41] The term "approximately" or similar as used herein should be construed as being

within 10% of the value stated, unless otherwise indicated.

[42] The foregoing description, for purposes of explanation, used specific nomenclature

to provide a thorough understanding of the invention. However, it will be apparent to one

skilled in the art that specific details are not required in order to practise the invention.

Thus, the foregoing descriptions of specific embodiments of the invention are presented for

purposes of illustration and description. They are not intended to be exhaustive or to limit

the invention to the precise forms disclosed as obviously many modifications and variations

are possible in view of the above teachings. The embodiments were chosen and described

in order to best explain the principles of the invention and its practical applications, thereby

enabling others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that

the following claims and their equivalents define the scope of the invention.

Claims (17)

1. Claims 1. A pick back flushing spray comprising a nozzle, the nozzle configured for engaging a spray body to receive water flow therefrom via an inlet of the nozzle in use, the nozzle comprising a central bore and at least one helical bore at least partially around the central bore connecting the inlet and an outlet thereof.
2. 2. A spray as claimed in claim 1, wherein the at least one helical bore comprises first and second helical bores.
3. 3. A spray as claimed in claim 2, wherein the nozzle comprises an inlet stage chamber leading from the inlet, the inlet stage chamber having an inlet end face funnelled to the central bore coaxially and wherein the first and second helical bores lead off tangentially from the end face oppositely adjacent the central bore.
4. 4. A spray as claimed in claim 3, wherein the inlet end face is frustoconical.
5. 5. A spray as claimed in claim 2, wherein the nozzle comprises an outlet stage chamber leading to the outlet, the outlet stage chamber having an outlet end face funnelled to the outlet and an inlet end face and wherein the first and second helical bores lead in tangentially to the inlet end face oppositely adjacent the central bore.
6. 6. A spray as claimed in claim 5, wherein the outlet interface is frustoconical.
7. 7. A spray as claimed in claim 1, wherein the nozzle comprises a head defining a rear annular edge.
8. 8. A spray as claimed in claim 7, wherein the nozzle comprises threading for engaging threading of a nozzle retention chamber of a spray body.
9. 9. A spray as claimed in claim 3, wherein the inlet end face comprises an arc of approximately 90.
10. 10. A spray as claimed in claim 5, wherein the outlet interface comprises an arc of approximately 90.
11. 11. A spray as claimed in claim 2, wherein each helical bore rotates through 180.
12. 12. A spray as claimed in claim 1, wherein the nozzle comprise coaxially opposing insertion tool tine engagement apertures.
13. 13. A spray as claimed in claim 1, further comprising the spray body and wherein the nozzle is configured for engaging an open nozzle retention chamber of the spray body.
14. 14. A spray as claimed in claim 13, wherein the spray body comprises a longitudinal bore leading from an inlet to the nozzle retention chamber and wherein the nozzle inlet interfaces the nozzle retention chamber to receive water flow via the longitudinal bore in use.
15. 15. A spray as claimed in claim 14, wherein the nozzle comprises threading for engaging

    threading of the nozzle retention chamber.
16. 16. A spray as claimed in claim 15, wherein the nozzle retention chamber comprises a

    back off at the nozzle inlet.
17. 17. A spray as claimed in claim 14, wherein the nozzle comprises a head defining a rear

    annular edge and wherein the nozzle retention chamber widens to a mouth at an annular

    periphery.

    Figure 1 1/4