AU608930B2 - Head scraper - Google Patents

Description

689

COMPLETE

SPECIFICATION

FOR OFFICE USE Application Number: Lodged; Complete Specification Priority: Related Art: Class Int. Class Lodged: Accepted: Published:

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PrintLing, TO BE COMPLETED BY APPLICANT toS 0 Name of Applicant: BERGWERKSVERBAND GMBH Address of Applicant: Actual Inventor: S Address for Service: Franz-Fischer-Weg 61, 4300 Essen 13, West Germany PETER KOSTER SMITH SHELSTON BEADLE 207 Riversdale Road Box 410) Hawthorn, Victoria, Australia Complete Specification for the invention entitled: IMOA SC...APER The following statement is a full description of ;his invention, including the best method of performing it known to us: Page 1 Our Ref: JC:GDberg Oi 13 1 z' ed 9 II Y u 7T The invention relates to a head scraper for belt conveyors which consists essentially of a scraper strip adapted to be pressed against the belt webbing and extending at least over the loading width of the belt webbing.

So-called head scrapers of the aforementioned type are known which are arranged spring-mounted acting on the belt in a guide arranged radially with respect to the drum centre point beneath The drum axis.

o i 0 4 0 00 00 S1, With the attachment of the scraper strip in the radial arrange- So ment within this region the centrifugal force obtaining in "0 0 this region due to the conveyed material adhering to the 04 belt surface is employed in order to thus obtain by means of the scraper an improved cleaning effect. Another advantage of attaching the scraper in this region is the advantageous removal of the scraped-off material which is transferred with the aid of gravity to the conveyor belt lying beneath o.0O the transfer point.

A disadvantage which however becomes apparent with such head P scrapers is that such an arrangement does not permit adequate yielding of the scraper strip on passage of belt webbing irregularities, in particular mechanical webbing joints.

The wear due primarily to the mechanical band or webbing joints leads to a very rapid and premature decline in the expected cleaning action. A further disadvantage of this known head scraper is to be seen in the application force dependent on the spring characteristic. In addition, maintenance of these apparatuses and their repair are very time and cost intensive.

r~Lllr* srr~ii IILC-u-r i'r t c oi i 6, GJ ml M1 I rIRItIJ' UI KAL thUUIR SANDERCOCK, SMITH BEADLE PO. Box 410, Hawthorn 3122, Australia Telephone (+613) 819 2099 Telex: 34491 Sandpat Telefax No. +61 3 819 1334- Group 3 To: Commissioner of Patents, Australia "(Stahl) (2f G a hYle n Signature(s) of declarant(s).

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0 aL o v 0. 0 0 00 0 0 0 coo 00 0 o0 0 o .o In the light of this prior art the invention is based on the problem of prcwiding a head scraper which avoids the aforementioned c isadvantages in simple and economic manner and increases the operating life.

This problem is solved according to the invention in that the scraper strip is mounted or two tension arms pivotally articulated to both sides of a discharge drum and the fulcrum of the tension arms is arranged at the level of the drum axis at a distance behind the latter, the tension arms 10 being provided with spring elements for application of the scraper strip to the webbing surfaces to be cleaned.

The advantage of the apparatus according to the invention resides in the geometrical arrangement and construction, The pivotability of the scraper strip permits an almost force-free passage of the belt band or webbing.

On passage of band webbing thickenings, in particular mechanical webbing joints, the scraper strip can be entrained in the conveying direction so that a gap arises between the belt surface and the scraper which permits an almost wearfree yielding within a predetermined angle, or the scraper ,;trip is momentarily lifted from the belt webbing by a pivot means.

On normal loading of the scraper strip by the belt surface the wear is compensated by pivoting provided oppositely to the running direction. By the specific articulation of the tension arms carrying the scraper strip behind the drum axis in conjunction with the spring action the application force is varied in dependence upon the coefficient of friction between the belt surface ard the scraper. With increasing coefficient of friction the application force diminishes and with diminishing coefficient of friction the application force increases.

Si 0 Ont a me sal late revei the cylil valvE by mE 10 upon dela Cr Ge C oIt c o C runni Go cscra 00 15 bloc] 04 be de thes 00.00 again 0 0 0:000 this 0 00 20 rear 00000: a spr 0 0 origi o *i The a resid 25 scrap inga Two e andw Fig.

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3- On the other hand, the raising of the scraper on passage of a mechanical belt joint may be effected by momentary reversal of pivot elements which act on the tension arms disposed laterally of the dischacge drum. The pulse detection for reversing the fluid-actuated pivot elements, for example in the form of a cylinder-piston arrangement or as bellows cylinder having an electronically precontrolled pneumatic valve, is selectively contactless via an inductive sensor or by means of a sensing roller and microswitch. In dependence upon the installation situation and the belt speed a time delay is necessary, i.e. synchronization of the operations.

0 r of It can happen that for example due to repair work return running of the belt band or webbing cannot be avoided. The tl oo scraper strip or the scraper elements would then lead to a 15 blocking so that on increasing the force the scraper would o 00 0o be destroyed. To avoid these possibly occurring difficulties the scraper strip is made pivotally between the tension arms against the running direction of the belt webbing. Due to ~oe this pivotability the scraper strip yields in the event of 0 20 rearward running. On normal operation of the belt webbing S a spring subsequently pulls the scraper strip into the 0000o0 0 original operating position.

The advantage of the head scraper according to the invention resides in a considerably increased operating life of the scraper strip and in a longer-lasting more effective cleaning action.

Two examples of embodiment are illustrated in the drawings and will be explained in detail hereinafter. In the drawings: Fig. 1 shows a schematic partial view of a belt discharge drum with a head scraper, -4 Fig. 2 shows an example of embodiment of a li-fing means for a head scraper, Fig. 3 shows a further example of embodiment of a scraper with pivot means against blocking on rearward running of the belt webbing.

The belt band or webbing i indicated in Fig. 1 is guided by means of a discharge or guide drum 3. The running direction of the belt band or webbing 1 is denoted by an crrow. At the level of the drum axis 6 but at a distance a behind the .00 0 0o. 10 drum axis on either side of the discharge drum 3 a respective oo 00 tension arm 4 for receiving a scraper strip 2 is articulated oo at a fulcrum 5. In the example of embodiment illustrated o 006 o in Fig. 1 the pressure of the scraper strip 2 on the band 0 000 surface to be cleaned thereby is obtained by a spring element o «o 15 7 constructe 1 as tension spring. The articulation of the tension arms 4 provided outside the drum axis 6 permits a 0000o wear angle a having a magnitude of about 400 directed oppo- 0oo sitely to the running direction of the belt webbing 1. The Co angle a v is followed in the running direction of the belt 20 webbing by a yield angle a which in adaptation to the oo°,o9 a elasticity of the tension arms 4 achieved by the spring on occurrence of a band thickness permits the almost wear-free ,o entraining of the scraper strip 2. Instead of the spring element 7 used in the example of embodiment illustrated in the drawings it is possible within the scope of the invention to construct the spring element 7 as torsion spring which is articulately connected in the region of the fulcrum As apparent from the example of embodiment illustrated in Fig. 2 in the region of the discharge drum 3 a scraper strip 2 articulately connected to tension arms 4 is disposed.

The tension arms are each connected to a pivot element 11, for example in the form of pressure-actuated cylinders. The pivot elements 11 or cylinders are double-action, can be acted upon in two directions, or are constructed as single-action cylinder, the return force being ensured via a spring element 7.

To determine the instant for raising the scraper strip 2 for the free passage of the mechanical belt joint 8 the belt joint 8 is detected via a sensing means 9 which is followed by a signal processing means 10 which via an electrically precontrolled pneumatic valve controls the pivot element 11.

The sensing means 9 may be constructed as contactless sensing means in the form of an inductive sensor or alternatively 10 as mechanical sensing means in the form of a sensing roller with following microswitch.

In the example of embodiment illustrated in Fig. 3 the tension arms 4 are pivotal via a rotation element 7, the rotation ooo 00o elements 7 being constructed as torsion spring 13. The torsion spring 13 of known construction consists essentially of two square tubes disposed offset within each other with o° e:0 rubber blocks 18 disposed therebetween., The inner square o000 tube is arrested fixedly or adjustably within a shift metal plate 16 so that the outer square tube is pivotal in the 20 range of the spring elasticity of the rubber blocks 18 with respect to the inner square tube. The outer square tube is connected to a lever 14. A tension plate 15 is mounted on the lever 14 pivotally in the vertical plane and in turn pivotally connected respectively to the tension arms 4 so that said tension armc 4 are pivotally mounted in the fulcrum in and oppositely to the belt running direction.

The scraper strip 2, which is shown in the example of embodiment illustrated as square tube with attached scraper elements 12, is pivotal against the force of a spring 17 about the fulcrum 19 through a predetermined amount. In this manner the scraper 2 is able on possible return running of the belt webbing 1 to yield in the direction of the rearwardly running belt webbing 1. The forward running of the belt webbing 1 6 is indicated by the arrow V and the rearward running by the arrow R in Fig. 3. On starting operation of the belt system again in the conveying direction provided the scraper strip 2 is pivoted by the spring 17 back to the original position to be referred to as operating position.

The claims form part of the disclosure of this specification.

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Claims (9)

1. Head scraper for belt conveyors which consists essentially of a scraper strip adapted to be pressed against the belt webbing and extending at least over the loading width of the belt webbing, characterized in that the scraper strip is mounted on tension arms pivot- ally articulated to both sides of a discharge drum and the fulcrum of the tension arms is arranged at the level of the drum axis at a distance behind the latter, the tension arms being prov:ded with spring elements for application of the scraper strip to the webbing surface to be cleaned,

2. Head scraper according to claim 1, characterized in that the spring elements are constructed as torsion springs and arranged in the fulcrum of the tension arms.

3. Head scraper according t- claim 1, characterizedin that the spring elements are formed as a torsion spring acting via a lever in conjunction with a tension plate on the tension arms.

4. Head scraper according to claim 1, characterized in that the tension arms proceeding from the normal position are arranged pivotally against the running direction of the belt webbing in a wear angle of about 400 dependent on the drum diameter. Head scraper according to claim 1, characterized in that the tension arms are arranged pivotally in addition to the wear angle in the running direction of the

8- belt webbing in a yielding angle dependent on the drum diameter. 6. Head scraper according to claim 1, characterized in that the scraper is made pivotal by means of at least one pivot element, for example a fluid-operated cylinder, the pivot element being connected for reversal by means of an electrically precontrollable valve to a sensing means and a signal processing means. ooe oQ 10 7. Head scraper according to claim 6, characterized in that o° the pivot elements are arranged on either side of the discharge drum engaging the tension arms. 0 0 0 .11. o 8. Head scraper according to claim 6, characterized in that the pivot elements are constructed as double-action pressure-actuated cylinders. *0 a

9. Head scraper according to claim 6, characterized in that the pivot element's are constructed as single- acting cylinders in conjunction with the spring elements effecting the return force.

10. Head scraper according to claim 1, characterized in that the scraper strip is formed between the tension arms pivotally against the running direction of the belt webbing.

11. Head scraper according to claim 10, characterized in that the scraper strip is made pivotal against a spring in such a manner that there is constant rj contact between webbing and a scraper element of the scraper strip. .9

12. A head scraper substantially as hereinbefore described. a g ta parts, h miethods, processes, compounds and compositias erred to or indicated in the speg-jtti and/or claims of the a pp11c a ti 0Ial 1::y o r c oll ec t iv ely, a nd a ny a nd all1 tionas of anY t~so moef suzh, DATED THIS 6th January, 1989 SMITH SHELSTON BEADLE Fellows Institute of Patent Attorneys of Australia. Patent Attorneys for the Applicant BERGWERKSVERBAND GMBH ~.4t o 00 0* 0 q .00 0. o o coo 90 0 o 00 04 9000 0 C 4' 0 04 Ce 0 et S 0 Ott. 890106, !gdspe.008, B: ci 0 o 00 o o. 0 0" *s p 0 0s Belt webbing Scraper strip Discharge drum Tension arm Fulcrum Spacing Drum axis Spring element Wear angle Yield angle Mechanical belt joint Signal pickup Signal processing Pivot element Reversal scraper element Torsion spring Lever Tension plate Shift metal plate Spring Rubber blocks Fulcrum 00 '0 0 .1 004