AU784455B2

AU784455B2 - A moulded screen panel

Info

Publication number: AU784455B2
Application number: AU65354/99A
Authority: AU
Inventors: Russell Burchall
Original assignee: Polyscreen Pty Ltd
Current assignee: Sandvik Rock Processing Australia Pty Ltd
Priority date: 1999-03-22
Filing date: 1999-12-21
Publication date: 2006-04-06
Anticipated expiration: 2019-12-21
Also published as: AU6535499A

Description

V

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT 0 000000 000.* ~0 0* Applicant(s): POLYSCREEN PTY LTD A.C.M. 008 521 702 Invention Title: A MOULDED SCREEN PANEL The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 A MOULDED SCREEN PANEL This invention relates to a moulded screen panel and, in particular, to a panel for use in screening of wet, sticky material or the screening of material that tends to peg into the apertures or adhere to the screening surface.

Screening machines are well known which comprise a plurality of modular screening panels which are connected to a sub-frame. The screening panels are moved or vibrated by the screening machine so that when material is deposited on the screening panels, the material is screened by some of the material passing through apertures in the panels and other, larger material, being removed from the top of the panel.

In some applications, water is allowed to flow over the panel to facilitate the separation and screening of the material.

S: Problems which are encountered with the screening of wet, sticky material is that the material can merely peg into the apertures and the normal vibratory movement of the machine is not sufficient to dislodge the material or allow the material to screen through the panels. When water is :i used on some panels, the surface tension of the water, if the aperture size in the panel is very small, simply allows the water to flow completely over the panel without breaking and passing through the apertures in the panel.

30 This can lead to flooding in downstream parts of the production plant in which the screening machine is incorporated.

The present invention has for its object, to provide a screen panel which can overcome these problems.

H:\Luisal\Keep\Speci\Polyscreen 65354-99.doc 6/02/06 3 The invention may be said to reside in a moulded screen panel, including: a peripheral screen frame having first, second, third and fourth side walls; at least one intermediate frame member extending between any two of the first, second, third and fourth side walls; a plurality of preformed screen element segments bonded to the peripheral screen frame during moulding of the screen panel, a gap between adjacent screen element segments and a web located in the gap, the web being formed during moulding of the screen panel and the web bonding to the adjacent screen element segments; a spaced formed between the screen element segments and the at least one intermediate frame member during the moulding of the screen panel; and wherein the coupling of the screen element segments to the peripheral side wall and the space between the screen element segments and the at least one 20 intermediate frame member enables the panel to create a secondary vibration when the screening panel is in use on a screening machine by virtue of the screen element segments being able to move relative to the at least one intermediate frame member.

Since the screening element can perform a secondary vibration movement as well as the general movement of the entire screen deck on the screening machine, any apertures in the screening element are caused to flex open to a 30 slightly greater degree which assists in unpegging of any material which may have lodged in the apertures.

Furthermore, the secondary vibration assists in movement of fine particles over the screen, the disbursement over the screen deck and therefore their screening through the machine. If water is flowed over the machine, the secondary vibration also tends to break the surface tension of the water rather than merely allow the water to flow H:\Luisa1\Keep\Speci\Polyscreen 65354-99.doc 6/02/06 4 over the surface of the screen panel and therefore enable the water to flow through any apertures in the screen element.

In the preferred embodiment of the invention, the screen element segments are provided with apertures for enabling screening of material. However, in some embodiments, the screen element segments may be a blank without any apertures which may be mixed with other screen panels which do have apertures when a plurality of screening panels are installed on a screening machine.

The screen panels may include part circular recesses and bushes for facilitating coupling of the panels to a screening machine.

In one preferred embodiment of the invention, the screen element segments are injection moulded and located into a mould for moulding of the screen panel.

Preferably the space between the screen element segments and the at least one intermediate frame member is about 3 mm.

25 The invention also provides a method of forming a screen panel, including: moulding a peripheral screen frame having first, second, third and fourth side walls and at least one intermediate frame member extending between any two of the 9* 30 first, second, third and fourth side walls in a mould; ooobonding a plurality of screen element segments to e the peripheral screen frame during moulding of the screen panel; providing a tool in the mould which has a flange for location between the screen element segments and the at least one intermediate frame member so as to form a space between the screen element segments and the at least one H:\Luisa\Keep\Speci\Polyscreen 65354-99.doc 6/02/06 5 intermediate frame member in the completed moulded screen panel; and providing a gap between adjacent screen element segments and forming a web between the screen element segments in the gap during moulding of the screen panel so that the web bonds to the adjacent screen element segments.

A preferred embodiment of the invention will be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a screen panel embodying the invention; Figure 2 is a cross-sectional view along the line II-II of Figure 1; Figure 3 is a view of a screen element segment 20 used in the preferred embodiment of the invention; Figure 4 is a plan view of a mould with screen element segments in place in the mould; Figure 5 is a cross-sectional view along the line V-V of Figure 4; Figure 6 is a view along the line VI-VI of Figure 4; SFigure 7 is a plan view showing two elements in H:\Luisal\Keep\Speci\Polyscreen 65354-99.doc 6/02/06 6 place in a mould for the moulding of the screen panel; and Figure 8 is a side view of another embodiment.

With reference to Figures 1 and 2, the screen module 10 has a peripheral frame 12 formed of side walls 14, 16, 18 and The side walls 16 and 20 may be provided with semicircular cutouts 22 to enable panels to be connected to a frame of a screening machine (not shown) by a well known pin and bush type connection arrangement.

The panel 10 has a screen element section 24 which is bonded to the peripheral frame 12 about its periphery. A first intermediate frame member 26 extends between the sides 14 and 18 and a second intermediate frame member 28 15 extends between the side walls 16 and As is clearly shown in Figure 2, the screen element 24 is separated from the intermediate frame members 26 and 28 by a space S shown in Figure 2.

The separation of the screen element 24 from the intermediate frame members 26 and 28 by the space S enables the screen element 24 to undergo a secondary vibration between the dotted lines shown in Figure 2 in the direction of the arrows A and B when the screening panel is installed in a screening machine and vibrated by the screening machine. Thus, not only does the entire panel undergo vibration as dictated by movement of the screening machine, the screen elements 24 within the panels are able to vibrate up and down relative to the intermediate frame members 28 and 26 as shown by arrows B so as to set up a secondary vibration within the individual panels In the preferred embodiment of the invention, the screen element 24 is formed from a plurality of screen element segments 24a as shown in Figure 3. The segments 24a are injected moulded in a separate moulding process to that \\melb-til s\home$%Daulad\aep\Ppeei\POYco.1ete .doc 20/12199 1 7 which forms the complete screen panel 10. The segments 24a are located within a mould (which will be described in more detail with reference to Figures 4 to 7) for formation of the screen panel 10. However, in other embodiments, the screen element 24a could be moulded with the remainder of the screen panel 10 or the screen element 24 may comprise a blank without apertures also moulded in the same operation as the remainder of the screen panel The segments 24a have apertures 25 and the peripheral side walls 29, 31, 33 and In the embodiments shown in Figures 1 and 2, four segments 24a make up the complete screen element 24.

With reference to Figures 4 to 7, the screen panel 10 is formed in a mould 50 which has a rectangular shaped recess 52. Located within the recess 52 are four tool elements 56. The tool elements 56 have an upper flange 58 about 20 part of their periphery as best shown in Figure 7. As will be clear from Figures 5, 6 and 7, when the tools 56 are located within the cavity 52, they will define gaps 61 S"which will form the intermediate frame members 26 and 28 when moulding material is poured into the mould 50. As will also be apparent from Figure 7, the gaps 61 extend all the way to side gaps 63 which will form the peripheral frame 12 of the panels As is also clear from Figures 5 and 6, the flanges 58 of adjacent tools 56 contact one another so as to prevent moulding material from passing between the tools 56.

As should be apparent, the flanges 58 define the spaces S between the intermediate frame members 26 and 28 in the completed panel The segments 24a are located on the tools 56. The side \\melbfies\hoaeS$paulad\KeepspeimPi\pOLyscPU.p 3 3 9 complete.doc 20/12/99 edges 33 and 35 of the segments 25 will define gaps 65 and 67 above the tools 56 which extend parallel and above the intermediate frame members 26 and 28.

In order to form the panels 10, polyurethane material is flowed into the mould 52 so that the polyurethane material flows about the gap 63 forming the peripheral side frame 12, through the gap 61 forming the intermediate frame members 26 and 28 and also through the gaps 65 and 67 forming webs 69 and 71 between the segments 24a which webs 69 and 71 form part of the completed screening element 24 of a completed screen panel The polyurethane material which is flowed into the mould 52 15 will bond to the side edges 29, 31, 33 and 35 of the segments 24a to thereby firmly and securely bond the screen element 24 within the completed panel 10. The screen element 24 is therefore effectively bonded about its entire outer periphery to the peripheral frame member 12 formed by 20 the side walls 14, 16, 18 and 20. The segments 24a are also bonded to the webs 69 and 71 but are free of and.

spaced from the intermediate frame members 26 and 28.

Thus, the effective screening element surface defined by all of the segments 24a and the webs 69 and.71 are suspended about their periphery within the frame 12 but are otherwise free to move relative to the intermediate frame members 26 and 28 to set up the secondary vibration previously described. A trampoline effect is therefore created because of the connection of the screen element 24 only about its periphery and the fact that the screen element is not connected to the frame members 26 and 28.

After the panel has set within the mould 50, the panel is removed from the mould 50 and the tools 56 separated from the panel 10 to thereby leave the completed panel 10 as shown in Figures 1 and 2.

\\melbfiles\home$\paulad\Keep\specl\POLYSCREEN.p33906 coElete.doc 20/12/99 9 If desired, and is usual, reinforcing frame members formed from steel or other suitable material can be located within the mould 50 so as to reinforce the peripheral frame 12 and also the intermediate frame members 26 and 28 if desired.

Figure 8 shows another embodiment of the invention which is constructed identically to the embodiment previously described except that in this embodiment the web 69 is of greater height than the surface 24b of the screen element 24 as shown by reference numeral 69a and side wall 16 is also of greater height as shown by reference 16a. The increased height of the web 69a and side wall 16a assists in causing water, which will flow in the direction of arrow 15 C in Figure 8, to tumble as it passes over the panel and therefore to further assist breakage of its surface tension to facilitate drainage and flow of water through the panel 20 Although in the preferred embodiment of the invention, the screen element 24 is formed from segments 24a which are injection moulded and then located in the mould 52, the screen element 24 could be formed at the same time as the remainder of the panel by locating cores (not shown) on top of or below the tools 56 (which may be integral with the tools 56) for defining the apertures and thereby enabling the screen element 24 to be formed in the same moulding operation as the remainder of the panel 10 and integral with the panel When material is loaded onto the screen panels, the random location of material on the panels will also tend to give a randomness to the secondary vibration which assists in the screening effect and does not merely set up a continuous harmonic which can cause material to deposit on some parts of the screening element rather than others and peg some parts of the screening surface of the screening machine.

\\melblilIes\hon\paulad\Keep\apeci\POLYSCREEN.p33906 coplete.doc 20/12/99 10 If no material is on the panel and water is simply flowing over the surface, the second vibration may create a substantially constant or uniform harmonic motion of the panel but nevertheless this harmonic motion will still be sufficient to break the surface tension of the panel thereby causing the water to flow through the apertures of the screening element 24 rather than merely flow off a side edge of the panel and flood downstream parts of the -processing plant Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this invention is not limited to the particular embodiments described by way of 15 example hereinabove.

a o o \\melb_ea\homeS\paulad\KCeP\spei\POLYSCREN.p3396 cOnWlete.doc 20/12/99

Claims

1. A moulded screen panel, including: a peripheral screen frame having first, second, third and fourth side walls; at least one intermediate frame member extending between any two of the first, second, third and fourth side walls; a plurality of preformed screen element segments bonded to the peripheral screen frame during moulding of the screen panel, a gap between adjacent screen element segments and a web located in the gap, the web being formed during moulding of the screen panel and the web bonding to the adjacent screen element segments; a spaced formed between the screen element segments and the at least one intermediate frame member during the moulding of the screen panel; and wherein the coupling of the screen element segments to the peripheral side wall and the space between the screen element segments and the at least one 'I 20 intermediate frame member enables the panel to create a %9 secondary vibration when the screening panel is in use on a screening machine by virtue of the screen element segments being able to move relative to the at least one intermediate frame member. 25

2. The panel of claim 1 wherein the screen element segments are provided with apertures for enabling screening of material. se. 30

3. The panel of claim 1 including part circular recesses and bushes for facilitating coupling of the panels to a screening machine.

4. The panel of claim 1 wherein the screen element segments are injection moulded and located into a mould for moulding of the screen panel.

The panel of any one of claims 1 to 4 wherein the H:\Luisal\Keep\Speci\Polyscreen 65354-99.doc 6/02/06 12 space between the screen element segments and the at least one intermediate frame member is about 3 mm.

6. A method of forming a screen panel, including: moulding a peripheral screen frame having first, second, third and fourth side walls and at least one intermediate frame member extending between any two of the first, second, third and fourth side walls in a mould; bonding a plurality of screen element segments to the peripheral screen frame during moulding of the screen panel; providing a tool in the mould which has a flange for location between the screen element segments and the at least one intermediate frame member so as to form a space between the screen element segments and the at least one intermediate frame member in the completed moulded screen panel; and providing a gap between adjacent screen element segments and forming a web between the screen element 20 segments in the gap during moulding of the screen panel so that the web bonds to the adjacent screen element segments.

7. The method of claim 6 wherein the space between the screen element segments and the at least one 25 intermediate frame member is about 3 mm.

8. A moulded screen panel substantially as hereinbefore descried with reference to the accompanying drawings.

9. A method of manufacturing a screen panel substantially as hereinbefore described with reference to the accompanying drawings. Dated this 6th day of February 2006 POLYSCREEN PTY LTD By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia H:\Luisal\Keep\Speci\Polyscreen 65354-99.doc 6/02/06