WO2002041685A1

WO2002041685A1 - Press ring method

Info

Publication number: WO2002041685A1
Application number: PCT/GB2001/005160
Authority: WO
Inventors: John Cousins
Original assignee: Cousins Of Emneth Limited
Priority date: 2000-11-24
Filing date: 2001-11-23
Publication date: 2002-05-30
Also published as: GB2369281A; AU2002223873A1; GB2369281B; GB0028681D0

Abstract

A method of making a generally dish-shaped ring element and assembling same for use as one of a pair of such ring elements assembled face-to-face to define a hollow ring or disc for assembly in coaxial relationship with similar hollow rings or discs to form a gang of an agricultural cultivator press or furrow press comprises the step of shape-forming at least the rim portions of the ringportions by metal spinning whereby cost-effective reduction of manufacturing tolerances enables stress reduction on assembly and in use and the minimisation of soil entry and improved performanceand life.

Description

PRESS RING METHOD

This invention relates to press rings for press type cultivators or cultivator presses and more particularly to a method of making press rings and mounting same in relation to a rotary shaft or axis for use in such cultivators .

There is disclosed in GB 2323511B a press type cultivator having hollow discs and in that specification it is taught that by adopting the illustrated disc profile certain rather specific soil effects can be achieved namely that by the use of such profile there is produced not only a soil cutting but a soil compressing and a crack- propagating effect. We have discovered by means of diligent research that such properties can only be achieved on the basis of the ring structure disclosed in the GB 511B specification, namely the use of assembled pairs of face to face dish structures assembled coaxially with substantial axial compression so as to achieve the effect of ring profile modification by compression, thereby enhancing the projecting lip effect and thus the degree of taper achieved in the assembly. Moreover, our research shows that the cutting effect which is identified as the basis upon which the claimed assembly is distinguished from the prior art depends upon the use of the above-described assembly of face to face (but otherwise unattached) dish-shaped ring elements in which each is structurally independent of its neighbour, so that each can produce its own cutting effect in a manner analogous to that which would apply if the ring elements were not mounted face to face but were separately mounted as independent dish or disc shaped elements. In short, the cutting effect is largely affected by the fact that the ring elements are not (for example welded together in the manner disclosed in DE 20 30 448 Van der Lely) . Moreover we have discovered that the soil compressive and crack-propagating effects of the claimed profile in GB511B are merely a function of the weight of the implement as is well known to any competent practioner in this field. Indeed any such implement of at least moderate weight will achieve a degree of soil compression by virtue of the support of the implement's weight on the relatively small contact surface area of the assembly of rings.

So far as crack propagation is concerned the compression at the location of the individual rings produces, obviously, some degree of accommodation of the tilled earth surface layer to the weight and profile of the row of rings,- and (depending on the moisture content of the earth) some degree of widening of the thus-produced soil slots.

Accordingly, our research has thus shown that the cutting effect of the rim portion of the GB 511B specification is largely due to the specific assembly method for the twin elements of the hollow ring structure, and the claimed effect of the peripheral wall and of its continuous curved profile and the soil-compressing and crack-propagating function of the peripheral wall are no more than those effects which would inevitably be produced by a ring profile of this kind such as that produced by the assembly of rings disclosed in the DE 20 30 448 (Van der Lely) specification, though of course no reference to such functions in the description accompanying those drawings is to be found since the functions are of no particular interest except as a basis for patent protection. A further aspect of the research we have conducted in this area relates to the structure and method of forming of the twin side elements of the hollow ring profile. Thus, we have discovered that there is a relationship between the ring element formation method and its method of mounting in relation to an associated ring element as a pair constituting a hollow ring, and the overall structure of the assembly. More specifically, we have . discovered that the traditional heat formation techniques employed in the production of agricultural rotary tillage elements of this kind lead to production tolerances of a substantial magnitude and have consequences in relation to the proper assembly of twin ring elements of this kind in a coaxial assembly.

In short, we have been able to show that there is a particular need for modest tolerances in relation to the assembly of rotary ring elements in pairs as a coaxial assembly in order that the proper ring element relationship is established in the assembled structure for ultimate use under the arduous conditions in which such rotary rings are used (and which have in the past been the province mainly of solid cast Cambridge type rings) , so that, despite being hollow in construction, the essentially fabricated structure can withstand the metallic stress produced during use without admitting particles of soil into the hollow ring structure, for example between the confronting faces of the dish-like ring elements, whether they are physically joined or compressed together. It will be appreciated that the very location where each individual press ring assembly is subjected to the maximum degree of soil abrasion and impact stress, not to mention the effect of the substantial weight of an implement of this kind arising not only from the ring members themselves and associated mounting structures, but also from the very substantial weight of the associated frame together with the effect (in the case of a fully mounted implement) of any downward loading arising from a tractor 3 point hitch and/or the soil effect of associated implement such as plough shares in the case of a furrow press .

Thus, what we have shown is that there is an approach to the construction of hollow disc structures for use as press rings in press-type cultivators including furrow presses and cultivator presses which meets the technical requirements discussed above in relation to the assembly of pairs of ring elements, the difficulties of forming same with the adequate reduction of tolerances (meaning greater accuracy) , without the automatic consequence of unacceptable production cost, so that there results an economic assembly.

Thus, the end result of our research in this area leads to the following. We have discovered that the technique of metal spinning as applied to this specific form of agricultural tillage element (having a hollow structure formed by twin dish-like elements) , for use under the arduous conditions discussed above, can be remarkably improved by the adoption of the technique of metal-spinning as the basis for the production of the dish-like format, with the result that the resultant hollow dish or ring format structure has significantly enhanced performance in use under field conditions. According to the invention there is provided the method and apparatus defined in the accompanying claim. In embodiments of the invention described below there is provided a method and apparatus in which, by the use of the technique of metal spinning in relation to the production of the individual profiles and generally dish-like ring elements (to be arranged in pairs to provide the hollow ring structure) there is produced a level of production accuracy (meaning, in agricultural terms, relatively low tolerances) resulting in excellent inter-element face-to- face cooperation in the assembled state. As a result, the embodiments of the invention provide an assembly, which, whether the ring elements are welded together or clamped together under an axially-directed load as in the GB 511B specification, the resultant assembly has enhanced operational characteristics. Due to the greater accuracy of production (as compared with conventional techniques for the production of such elements) the joint area where the dish-like members are in the closest face-to-face contact or welded assembly, the dynamic levels of stress produced during tillage operations are markedly reduced (as compared with the comparable implement using conventionally produced ring elements) so that the tillage effect and your ability under such conditions of use, not to mention soil penetration and production of the requisite post-cultivation soil profile are all significantly enhanced.

It is not claimed of course, that the technique of metal spinning has any general novelty in relation to the production of symmetrical components utilised in heavy industry, such being a technique which is by no means new. It is not claimed likewise (though it is now known) that metal spinning has not been used in agriculture for the production of one structure or another, when convenient. What is claimed is that, to the best of the Applicants' knowledge the technique of metal spinning has not been applied to the shaping of the individual dish-like elements of hollow ring structures for use in press-type cultivators, nor have the advantages arising from same which are specific to that assembly been discovered. This latter fact is not surprising since, to the best of our knowledge research of the kind to which we refer above has not previously been conducted until done by ourselves.

In the embodiments of the invention disclosed below a further significant advantage arising from the metal spinning production technique arises in relation to the assembly of the individual ring elements in pairs as a coaxial assembly, as follows. It is clear to us from our research that the reason for the adoption of the compressed assembly of ring elements as disclosed in the GB511B specification largely relates to the inter-related production and assembly and soil-exclusion factors discussed above. The relative extreme complication of the multi-component assembly of ring elements and bearings and thrust-transmitting structures etc. etc. for use in a tillage tool of a generally simple and robust kind and intended to be used under extremely arduous conditions, can only be explained in such terms . The answer to the production tolerance problems inherent in prior techniques for production of hollow ring elements have led to this mechanically ^' complicated and consequentially costly structure to provide a technical solution. Moreover, it appears from marketplace factors that despite the cost and complexity of the assembly the requirement for press-type hollow ring implements of this kind remains unsatisfied, or only partially satisfied, due perhaps to the cost factors mentioned above.

Thus, in the embodiments of the invention disclosed below, we provide a hollow ring structure employing pairs of dish-like elements produced using metal-spinning techniques. The hollow ring structures have resultant greater accuracy and lower stress in use. Moreover, the ring elements can be used either in relation to a welded structure utilising a common tubular shaft, or indeed in relation to assemblies of the kind disclosed in the GB511B specification in which the majority of the structure is unwelded and the main pairing assembly of the ring elements is achieved by axial loading. In this latter case, the level of axial load needed to produce the required inter- element co-operation does not need to include the same element of load for ring element-deformation (to remove production lack of uniformity) so that soil between the ring elements is minimised.

In the illustrated embodiments described below the ring elements are mounted in pairs as a welded assembly on a common tubular shaft having internal bearings and the whole structure is of remarkable simplicity and ruggedness for extended use under the arduous conditions concerned.

*An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

Fig 1 shows a sectioned gang of a press-type cultivator, the section being taken in the longitudinal axial direction of the gang and showing the assembled multiple hollow rings in side by side arrangement with respect to a central mounting tube having internal bearings ;

Fig 2 shows, in a similar sectioned view, one of the hollow rings of the gang of Fig 1, removed from the tube; Fig 3 shows, in a similar view to that of Fig 2, a single ring element of dish-shaped format forming one half of the ring of fig 2 ;

Fig 4 shows a side elevation view of the ring element of Fig 3 as seen in the direction of arrow IV in Fig 3. The apparatus of Figs 1 to 4 is intended for use in an agricultural machine of the cultivator press kind. An example of the use of an implement gang of the kind seen in Fig 1 is to be found in DE20 30 448 (Van der Lely) in which the gang is employed at the rear of a rotor power cultivator which is mounted on the three point hitch of an agricultural tractor. So far as disclosure of an example of the use of the implement gang is concerned, reference is hereby directed to the DE448 specification of which the disclosure is incorporated herein by reference. Turning now to the construction of the apparatus seen in Figs 1 to 4 , this comprises an implement gang 10 of a press-type agricultural cultivator in which there is provided a central mounting tube of relatively large diameter, for example 276 mm, and having internal end bearing assemblies 14,16 which are end-acccessible for maintenance purposes and the entire assembly is of substantial and robust construction, which is readily achieved by the use of a substantial diameter preformed tube and having a diameter in the range of 150/400 mm. Mounted on the central mounting tube 12 at equally- spaced positions throughout the length thereof are 11 (in this example, but the gang may be significantly longer) press rings 18 having a general construction in terms of external profile, which is broadly similar to that of the DE448 specification, but with significant differences with respect to mode of construction and manufacture as discussed in detail below.

Each of the press rings 18 comprises a pair of press ring elements 20,22 of generally dish-shaped format and disposed in face-two-face relationship with their rims 24 in continuous peripheral contact, as will be more fully described below.

Turning now to the details of the construction of the press ring elements 20,22, these comprise the following structures forming part of the generally dish-format press ring element, namely a dish base portion 26, a dish wall portion 28 and a dish rim portion 30. The dish base portion is generally flat, the dish wall portion is generally short and steeply angled with respect to the base portion so as to exert a compressive effect. The rim portion corresponds to the rim seen in the DE448 specification and the effect is generally similar.

Turning now to the method of construction of the hollow press rings 18, the method of making and assembling these in face-two-face relationship to define the hollow ring or disc structure for assembly in co-axial relationship on the gang 10 comprises initially forming the press ring elements 20, 22 in a forming step comprising shape forming by means of metal spinning at least the rim portions 30 thereof. The technique of metal spinning comprises forming the hollow shape of the press ring elements by application of lateral pressure to a rapidly revolving metal blank on a lathe, so that the metal assumes the shape of a former (not shown) which is rotating with it. In other words, a former is provided having the complementary convex shape corresponding to the concave shape of the press ring elements, and a blank is mounted on it and rotated with it while deformation is effected by a combination of bending and stretching pressure exerted thereon by means of a steel forming tool worked by an operator or by means of a mechanically-controlled roller. We have discovered that this process, which can be conducted at a significantly lower temperature than conventional heat-forming techniques for production of agricultural tillage blanks, produces a product having a noticeably dimensionally more accurate finish than has hitherto been possible.

Following forming of the ring elements, they are assembled in face-two-face relationship with each other in the generally co-axial assembly of Fig 1 and are then caused to be held in that assembled relationship, in this embodiment, by a welding step applied to the rim portions. Due to the lower tolerances achieved in the shape-formation step of the method, the compressive force required during the welding step of the assembly process is significantly reduced.

Amongst other modifications which could be made in the above embodiments are significant modifications to the size and profile of the press ring elements and of their mounting in relation to central tube 12, to which they are welded in this embodiment. It would be possible to adopt a construction in which a compression force is applied to the assembly of ring elements as disclosed in the 511B specification.

Claims

1 A method of making a generally dish-shaped ring element and assembling for same for use as one of a pair of such ring elements assembled face-to-face to define a hollow ring or disc for assembly itself in generally coaxial relationship with similar hollow rings or discs to form a gang of an agricultural cultivator press or furrow press, the method comprising a) forming said dish-shaped ring element in a forming step comprising a shape-forming step; and b) assembling said ring element in face-to-face relationship with another such ring element in generally coaxial relationship; and c) causing the rim portions of said ring elements to be held in said assembly in a defined assembled relationship in which said rim portions cooperate to effect, in use, soil cultivation while preventing or minimising the entry of soil particles between said rim portions; characterised by d) carrying out said step of forming said dish-shaped ring elements by metal spinning at least said rim portions of said ring elements; and e) carrying out said step of causing the rim portions of said ring elements to be held in said assembly in a defined assembled relationship by causing said rim portions, shaped by metal spinning, to cooperate as aforesaid to prevent or minimise soil particle entry.

2 A method of making a generally dish-shaped ring element for use as one of a pair of such ring elements in an agricultural cultivator characterised by carrying out a shape forming step in the production of said of ring element by metal spinning at least the rim portion of said ring element.

3 A method according to claim 1 or claim 2 characterised by carrying out said step of causing said ring elements to be held in said assembly in a defined or assembled relationship by welding said rim portions in said face-to-face relationship.

4 A method according to claim 1 or claim 2 characterised by carrying out said step of causing said rim portions or said ring elements to be held in said assembly in a defined or assembled relationship by axially compressing same.

5 A hollow ring or disc structure for use in an agricultural cultivator press of furrow press made by a method according to any one of the preceding claims.

6 A method of making a generally dish-shaped ring element and assembling same substantially as described herein with reference to the accompanying drawings.