GB2162809A - Auger - Google Patents

Abstract

Auger, e.g. for agricultural bulk transport or spreader vehicles, is built up from uniform flat sheet metal blades (11) mounted on a central shaft (10), each flat blade being shaped substantially as a sector of a circle with a radially inner corner portion attached to the shaft so that it lies in a plane at a pitch angle to the shaft and its radially outer leading corner is secured to the radially outer trailing corner of the next succeeding blade, arcuate outer edges (12) of the assembled blades forming a generally helical arrangement around the shaft axis. One complete turn of the auger may comprise four such blades mounted on respective side faces of a square section shaft. As shown adjacent edges are welded as at (10), (21) leaving triangular gaps (23) between successive blades. These gaps (23) may be left to provide agitation or a mixing action or they may be blocked by triangular fillets of sheet metal. <IMAGE>

Description

SPECIFICATION Auger This invention relates to augers for conveying, transferring, feeding or mixing materials, for exam ple as used in agricultural machinery such as transport or spreader vehicles for such applications as mixing and distributing animal feedstuffs or broadcast distribution of manures, fertilisers or slurry.

Some examples of spreader vehicles for agricul tural use incorporating augers are described and claimed in my British Patent 2080662 and my pending British patent applications 8406638 dated 14 March 1984 and 8413078 and 8413079 both dated 22 May 1984.

Various constructions and shapes of auger have been used. One known form is the archimedian screw, usually a single start helical blade having a continuous periphery. In other known forms a plu rality of individual angled blades or paddles are employed, for example similar to the blades of a propeller, with angular and/or axial gaps between them so that there is no continuous helical periph eral edge.

The archimedian screw type auger has the ad vantage of a smooth continuous periphery giving a steady feed rate and which is less likely to trap or become jammed by any foreign bodies present in the material, for example stones or the like. How ever this type of auger may not be effective in han dling all types of materials, particularly wet or sticky materials such as rotted straw-based farm yard manure as the screw blade may become com pletely clogged with material so that no forward transfer takes place and the auger merely rotates in a cylindrical tunnel through the material bulk.

For this reason augers having individual or dis continuous blades, vanes or paddles have been preferred for some applications with a view to pro viding a measure of agitation discouraging the ma terial from clogging or bridging. Such arrangements may also be preferred where a stir ring or mixing action is desirable.

Many known types of auger, particularly the ar chimedian screw type, are complex and costly to produce as they involve accurate cutting and shap ing of sheet metal to compound curvatures to form the necessary helix, fabrication as by welding has to be carried out with considerable care and skill, and repair of damaged equipment e.g. in the field may not be easy necessitating costly replacement of the whole auger.

The construction having separate blades or vanes is somewhat more easily fabricated and re paired but is not so strong as the loading on an in dividual blade may be considerable- particularly at the root where it is attached to a shaft of the au ger.

The object of the present invention is to provide a particularly simple auger construction which is readily and cheaply fabricated yet strong and re sistant to damage in use and which may provide a desirable measure of agitation or mixing to the material being handled.

According to the invention there is provided a material feed auger comprising an axially extending shaft and a plurality of uniform blades of sheet material each shaped substantially as a sector of a circle, each having a radially inner corner portion attached to the shaft at respective positions spaced both axially along the shaft and angularly clout the shaft, and each lying generally in a respective plane at a pitch angle to a diametral plane of the shaft; at least a radially outer leading corner of each blade being secured to the radially outer trailing corner of the next succeeding blade so that arcuate outer edges of the blades subtending said inner corner portions are disposed generally in regular and continuous helical relationship about the shaft axis.

Conveniently each blade is a planar sheet having two straight edges meeting at said corner at 90 and an outer edge of uniform curvature so that four blades make up one full turn of the auger helix.

The auger shaft may be of square section, a straight edge portion of each blade at the inner corner being attached across a respective face of the square section as by welding, and said outer corners of the respective blades also being secured together as by welding to complete the assembly.

In this way successive pairs of blades are inclined with respect to each other viewed in an axial plane so that said corners meet at an angle and provide a mutually buttressing effect which adds to the strength of the assembly, a triangular opening being defined by the adjacent straight edges of the respective blades and by the auger shaft through which a proportion of the material may be forced during rotation to provide a mixing or agitating effect.

For some applications it may be preferred to block each said triangular opening by e.g. by a simple fillet of sheet metal.

An example of the invention will now be more particularly described with reference to the accompanying drawings wherein: Figure 1 is an end elevation of an auger, and Figure 2 is a side elevation of a portion thereof.

The auger is built up on a square section central shaft 10, e.g. a tubular metal box section, and a plurality of flat sheet metal blades 11 of uniform dimensions and shape (Figure 2 shows five of the blades 11a-e).

Each blade 11 has a uniform radius curved radially outer edge 12 90 in extent so that four of the blades make up one complete circle or turn of the auger periphery; and a short and a long straight edge 13, 14 meeting at right angles to form a radially inner corner portion offset with respect to the centre of curvature of edge 12, the difference in length between the two straight sides being equivalent to the width of each face of the square shaft 10. In the example shown in the drawings if the face width of shaft 10 is x the length of edge 14 is 3x and the length of the shorter edge 13 is 2x.

It will be appreciated that other proportions of blade dimension could be employed, for example the angular extent of each curved edge could be more or less than 90" so that the number of blades making up one complete circle is less or more than four and the length and angle of the straight edges could be varied e.g. for use with a shaft 10 having less or more than four faces or for a shaft of circular section though such arrangements are less desirable because they complicate the fabrication.

Each blade 11 is arranged with the inner corner portion angled across a respective face of shaft 10, the inner one third (in this example) of the longer edge 14 being welded to said face, and the plane of the blade is also inclined at a pitch angle to a diametral plane of the shaft axis. Each successive blade is attached to a respective face of shaft 10 in the same way spaced axially from the last preceding blade and also spaced angularly at 90 about the shaft axis by being attached to the next succeeding shaft face, the curved edges 12 thus forming a generally helical arrangement around the shaft axis.

Each blade is further secured by having the radially outer leading corner (junction of short side 13 with curved edge 12) welded to the radially outer trailing corner (junction of long side 14 with curved edge 12) of the next adjacent blade, the welded junctions between blades ila and lib and between blades lic and 11d are indicated at 20,21 on Figure 2.

It will be seen from the way that the successive blades are angled that a triangular gap 23 (Figure 2) generally co-planar with a respective side face of shaft 10, is defined by the adjacent straight edges of successive blades and by a face of the shaft.

This gap may be left as an opening through which a certain amount of material may pass during operation of the auger, thus providing an agitating or mixing action and possibly discouraging clogging, or the gap may be blocked by triangular fillets of sheet metal.

The effective pitch of the blades can be selected to provide the desired feed rate and it is to be noted that standard shaped blades 11 can be arranged to provide a range of effective pitches readily determined by the angle at which they are welded onto shaft 10, it is not necessary to provide special shaped or curved components appropriate to any particular pitch.

For some applications it may be desirable to have different pitch angles at respective longitudinal locations along the same auger e.g. to provide fast feed from a remote part of a bulk container body or trough and a slower feed rate at or adjacent to a ~discharge opening thereof or vice versa and such variations can readily be provided using standard components.

The triangulated construction in which the adjacent blades are inclined with respect to each other and secured-together at the outer corners so that they buttress each other provides a particularly strong construction which is resistant to damage and the effectively continuous generally helical outer periphery made up of the curved edges 12 provides a generally smooth cylindrical envelope of revolution which is less likely to trap foreign bodies or become jammed.

If any damage does occur individual blades can readily be removed, flattened or straightened if bent, or replaced, thus repairs and maintenance are speedily effected, particularly under field conditions. Replacement blades can easily be cut from metal sheet, as they are planar no bending or shaping is required.

If desired multi-start helices on a common shaft and at various pitches can be provided, again using standard shaped components.

Claims (9)

1. A material feed auger comprising an axially extending shaft and a plurality of uniform blades of sheet material each shaped substantially as a sector of a circle, each having a radially inner corner portion attached to the shaft at respective positions spaced both axially along the shaft and angularly about the shaft, and each lying generally in a respective plane at a pitch angle to a diametral plane of the shaft; at least a radially outer leading corner of each blade being secured to the radially outer trailing corner of the next succeeding blade so that arcuate outer edges of the blades subtending said inner corner portions are disposed generally in regular and continuous helical relationship about the shaft axis.

2. An auger as in claim 1 wherein each blade is a planar sheet having two straight edges meeting at said corner at 90 and an outer edge of uniform curvature so that four blades make up one full turn of the auger helix.

3. An auger as in claim 1 or 2 wherein the auger shaft is of square section.

4. An auger as in claim 3 wherein a straight edge portion of each blade at the inner corner is attached across a respective face of the square section.

5. An auger as in claim 4 wherein said straight edge portions are welded to the faces of the square section and said outer corners of the respective blades are welded together to complete the assembly.

6. An auger as in any preceding claim wherein a triangular opening is defined by the adjacent straight edges of the respective blades and by the auger shaft, through which opening a proportion of the material may be forced during rotation to provide a mixing or agitating effect.

7. An auger as in any one of claims 1 to 5 including a fillets of sheet material positioned to block triangular openings defined by the adjacent straight edges of successive pairs of blades and by the auger shaft.

8. An auger substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

9. A transport or spreader vehicle including an auger as in any preceding claim.