AU608747B2 - Improvements to grader blade assemblies - Google Patents

Description

To: The Commissioner of Patents A. -PLCATV ON ACCEPTED AND AMEN,,DA4E1TS ALLOWED mr~

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-1- 608747 CO MMONT.WE; 1-TH OF ALET:-.AL'I The PtnsAct 1952-1969 Name Acrjicant: Thomas Anthony MEYERS AddrasS o Apolicant: 142 Field Stc,,et, MACKAY, Queensland, 4740

AUSTRALIA

Actua. TnVentor: Thomas Anthony MEYERS Address Z:r sevc:G. R. CULLEN COMPANY Patent and Tra-ce L11ark AttOrneyS Medibhank Buldin 82 Ann Stzeet BR2-S3ANT- QLD. Austrli.

C'-MPLTE. S PEC: F:C: ZN FOR THi ITNVENTI ON ENT:TL -D: "IMPROVEMENTS TO GRADER BLADE ASSEMBLIES" The followi-nc statement is a fUa~l deSCr2Ztiol of the invetionincluding the best method of Perf-orming it kncwn to uas: ~II. :i r f- 2 THIS INVENTION relates to improvements in replaceable picks for grader blade assemblies described in Australian Patent No. 568153.

Commonly, motor graders are provided with a mouldboard having affixed, thereto, say by bolting, a serrated cutting blade which is provided with a plurality of integrally formed cutting edges. In practice, it has been found that the serrated cutting edges are subject to breakage and this causes the motor grader to be stopped whilst the cutting blade is ,i0, unbolted and a replacement blade bolted on the mouldboard.

This arrangement is obviously time-consuming and relatively expensive as damage say to only one or two individual cutting edges may require the entire serrated cutting blade to be replaced.

The present invention is concerned particularly with the grading of unsealed earthen road surfaces which form a highly compacted crust after prolonged periods of use.

,i Typical of such hardened earthen road surfaces are mining haulways which are subjected to high levels of traffic with heavily laden vehicles.

It has been found that the use of pointed edges on a grader blade causes the brittle compacted earthen crust to fracture enabling the pointed cutting edges to deeply penetrate into the underlying softer earth surface causing the motor grader to stall. Even if the motor grader had sufficient power to overcome stalling the grading action would result in a loose uncompacted road surface which would quickly develop surface irregularities such as pot holes, 3 corrugations, ruts and the like due to the heavy traffic. it is important therefore in maintenance of such earthen roadways to be able to smooth out surface irregularities and at the same time maintain a highly compacted road surface, With conventional grader blades, the continuous cutting edge prevents the blade from penetrating the overlying compacted crust and the blade tends to simply skid along the road surface. There is a need therefore for a pick for a grader blade assembly which in u~ie is effective to shave the compacted road surface to remove irregularities therefrom without causing the compacted road surface to become fractured.

:0:90: Picks having a body with a hard faced cutting tip *0 0 0 and a mounting spigot are known in the field of rotary excavators. Rotary excavators have a rotating drum with a ~~each pick. Picks for rotary excavators generally have pointed tips with several hardened cutting faces and several cutting edges. This configuration is necessary to achieve the deep gouging action required of such excavators.

In Patent No. 568153 there is described an a~ssembly for attachment to the mouldboard of a motor grader. The assembly comprised a pisirality of cutting picks located in sockets in a mounting member attachable to the lower edge of a grader mouldboard. The cutting picks described in Patent No.

568153 comprise a body portion having a leading surface incl~ading a hardened metal alloy woY.king face attached thereto and a spigot-like supporting shank extending from an upper 4 surface of the body portion. The longitudinal axis of the spigot-like shank is substantially parallel to the plane of the working face.

Although generally effective for their purpose in shaving hard road surfaces there is a tendency for the pick to undergo torsional stresses about the longitudinal axis of the supporting spigot on certain types of road surface. These torsional stresses ultimately lead to wear bet.een the cutting pick and the mounting member in which they are located and consequently the picks are able to move in their respective •0 mountings which exacerbates wear. In addition wear and f'L resultant movement of the picks in their mountings reduces the effective cutting precision of the working faces.

According to the present invention there is provided a4 o a cutting blade assembly for attachment to the mouldboard of an earth grader, said blade assembly comprising:an elongate mounting member adapted for attachment along a lower edge of a grader mouldboard, said mounting member including along its lower edge a plurality of spaced sockets for releasably locating cutting picks in spaced relationship; and a plurality of removable cutting picks each locatable in a respective socket to form a discontinuous cutting edge along a lower edge of said blade assembly, each said cutting pick having: a supporting shank including retention means for releasably retaining said supporting shank in a respective one of said sockets; and 0og ATZ E T 1< a body portion having a leading surface, said leading surface including a hardened metal alloy working face having a transverse straight cutting edge adjacent a free end of said body portion remote from said supporting shank, said free end of said body portion extending rearwardly of said cutting edge to form a substantially planar ground engaging surface having an area sufficient to resist, in use, penetration of an earth surface by said cutting pick whilst allowing said cutting edge to effect a shaving action on the 0rt t earth surface, each said cutting pick being characterized in that the longitudinal axis of a respective supporting shank is inclined at an angle of from 50 to 850 relative to the plane of a respective working face.

In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein:- I Fig. 1 is an elevation view illustrating portion of a grader blade assembly incorporating replaceable picks t t according to the present invention; Fig. 2 is a cut away sectional view illustrating the grader blade assembly of Fig. 1 incorporating replaceable picks secured to a grader mouldboard; Figs. 3a-3d show various views of a typical replaceable pick according to the present invention wherein Fig. 3a is a rear elevation, Fig. 3b is a side elevation, Fig.

3c is a front elevation and Fig. 3d is a perspective view; and Fig. 4 is a view in the direction A-A of Fig. 2 i Referring to the drawings there is illustrated a grade blade assembly 10 including a mounting member 11 which is preferably cast and which is provided with a first arcuate portion 12 for attachment to a mouldboard 13 of conventional form and second mounting portion 14 having a plurality of spaced parallel bores or sockets 15 of circular cross section formed there which are adapted to mount respective replaceable points or picks 16.

As shown, the arcuate portion 12 on the mounting member 11 is apertured at spaced positions 17 for co-operation with corresponding apertures 18 in the mouldboard 13 so that respective bolts may be passed therethrough to mount the holder 11 to the mouldboard 13 as shown. The respective bores 15 in the mounting portion 14 are stepped outwardly at 19 adjacent their upper ends to define a shoulder 20 and the mounting portion 14 includes a downwardly directed flange 20' the purpose of which will hereinafter become apparent.

As shown in Figs 2 and 3 each replaceable pick 16 includes a main body portion 21 and a solid cylindrical mou. ting shank portion 22 of such diameter as to be closely received with a bore or socket 15 in the holder mounting portion 14. The main body portion 21 of the pick 16 includes a leading surface 21' which has supported at its operative lower end a generally rectangular hardened tip 23 preferably formed of a tungsten alloy which extends the full width of the face 21'. The rectangular configuration of tip -i L LI -7- 23 defines a generally linear lower cutting edge 23' so that maximum operative cutting area is achieved and so that in use a smooth finished ground surface will be formed.

The shank portion 22 is preferably provided with a broad groove 24 adjacent its upper end to receive a split connecting clip 25. The clip 25 is of generally annular form and preferably formed of resilient material such as spring steel strip. Furthermore the clip is provided with a number of outwardly directed projections or dimples 26.

As shown in Fig. 2, each pick 16 is adapted to be engaged with the mounting portion 14 of the holder 12 so that the shank portion 22 is closely accommodated within a bore 15 and the groove 24 of the shank portion 22 located adjacent the stepped portion 19 of the bore 15. In this position the clip 25 may spring resiliently outwardly so that the dimples or projection 26 are disposed within the stepped portion 19 of the bore for location behind the shoulder 20 to maintain the pick in an operative engaged attitude. Furthermore, a rear face 27 of the tip portion 21 of the pick 16 is located adjacent or in abutment with the flange 20' so that rotation of the point 16 relative to the holder 11 is eliminated or substantially reduced.

The longitudinal axis 30 of shank 22 is inclined at an angle a and relative to the planar face of hardened tip 23. Angle a is chosen to permit the longitudinal axis 30 to be generally parallel to the resultant of vertical and horizontal forces applied to the pick when in use. In this -8manner the resultant force applied to the pick is directed substantially along the longitudinal axis 30 and thus torsional forces on shank 22 are effectively eliminated. In this manner wear between shank 22 and the surface of bore as well as wear between rear face 27 and flange 20' is consequently substantially eliminated.

By eliminating torsional movement between the picks and the mounting member 11 this avoids excessive wear on cutting edges 23' which in combination with torsional movement of the working face 23 substantially reduces working efficiency of the picks.

The angle a has been found to be effective in the 0 0 range of 5 to 85 depending upon the nature of the road surface to be worked.

When it is desired to remove the pick 16, the clip must be radially compressed so that the dimples do not project radially outwardly beyond the diameter of the bore Of course, this may be achieved by a sharp tap of a hammer on the top end of the shank portion 22 which will cause the dimples 26 to ride up along the shoulder 20 so as to effectively radially compress the clip It will thus be seen that when it is necessary to change one or more picks, it is a simple procedure to remove the worn pick and replace it with a new pick which may again be simply tapped into position with the clip 25 being radially compressed by virtue of engagement of the dimples 26 with the leading ends of the bore 15 until the enlarged -9diameter portion 19 of the bore 15 is reached whereupon it will spring outwardly to positively locate the pick in position. Of course it will be realised that the clip may be in many different forms; for example, the clip may simply comprise a rubber ring which resiliently expands outwardly when the point 16 is located in its operative position to be partially located in the groove 19. in an alternative arrangement, the mounting portion 14 of the holder may be provided with a plurality of apertures adapted to be aligned with corresponding apertures in the shank portion of the pick so that a pin may be inserted through aligned apertures to maintain the pick in its operative attitude.

Whilst the above has been giveh by way of illustrative example of the invention, it will of course be realised that many modifications and variations may be made to the above described embodiment by persons skilled in the art without departing from the broad scope and ambit of the invention as defined by the appended claims. For example, in some instances the clip 25 may be totally eliminated and the shank 22 tapered to mate with a tapered portion of the bore 15 to frictionally hold the pick in position.

Claims (9)

1. A cutting blade assembly for attachment to the mouldboard of an earth grader, said blade assembly comprising:- an elongate mounting member adapted for attachment along a lower edge of a grader mouldboard, said mounting member including along its lower edge a plurality of spaced sockets for releasably locating cutting picks in spaced relationship; and o" a plurality of removable cutting picks each locatable in a respective socket to form a discontinuous cutting edge along a lower edge of said blade assembly, each o. said cutting pick having: 0 a °a support shank including retention means for o.o releasably retaining said supporting shank in a respective one of said sockets; and a body portion having a leading surface, said leading surface including a hardened metal alloy working face having a transverse straight cutting edge adjacent a free end of said body portion remote from said supporting shank, said free end of said body portion extending rearwardly of said cutting edge to form a substantially planar ground engaging S• surface having an area sufficient to resist, in use, penetration of an earth surface by said cutting pick whilst allowing said cutting edge to effect a shaving action on the earth surface, each said cutting pick being characterized in that the longitudinal axis of a respective supporting shank is inclined at an angle of from 50 to 850 relative to the plane 11 of a respective working face.

2. An assembly as claimed in claim 1 wherein said longitudinal axis of said supporting shank is inclined at an angle of from 150 to 750 relative to the plane of said working face.

3. An assembly as claimed in claim 1 or claim 2 wherein said longitudinal axis of said supporting shank is inclined at an angle of from 250 to 750 relative to the plane of said working face. S

4. An assembly as claimed in any preceding claim S wherein said longitudinal shank is inclined at an angle of from 450 to 650 relative to the plane of said working face. ,,rr S

5. An assembly as claimed in any preceding claim wherein said longitudinal shank is inclined at an angle of 600 relative to the plane of said working face.

6. A grader blade assembly substantially as o,4 hereinbefore described with reference to the accompanying 4 4 drawings.

7. An assembly as claimed in any preceding claim wherein said hardened metal alloy working face is comprised of S tungsten carbide alloy. 4 4 S

8. An assembly as claimed in any preceding claim wherein said hardened metal alloy working face comprises a rectangular body having parallel opposed faces.

9. An assembly as claimed in any preceding claim wherein said hardened metal alloy working face comprises a body located in a recess in said leading surface. An assembly as claimed in any one of claims 1-8 1W 21 ,I releasably retaining said supporting shank in a respective one of said sookets; and /2 I 12 wherein said hardened metal alloy working face comprises a body located on said leading surface. DATED this 14th day of January 1991 THOMAS ANTHONY MEYERS By their Patent Attorneys CULLEN CO. 00*4 o #1 o *9 44 4 0 04 4 44 4 4 4$ 0* 00 4 0 @4 09 0 0 4 4 0404 4444 4, 4 4 4444 o 4* 4 4 4 4444 4 0 4 4 4441 .444 440*44 4 p. 'i