GB2192524A - A cultivator tool - Google Patents

Abstract

A cultivator tool has a shank part (1) for attachment thereof to a tool- carrier, a substantially rigid operative part (3), and a springy elastic intermediate part (2) linking the operative part (3) to the shank part (1). The operative part (3) is a blade whose edges are symmetrically inclined with respect to the tool axis. <IMAGE>

Description

SPECIFICATION A cultivator tool This invention relates to a cultivator tool, particularly, but not exclusively, suitable for rotary harrows.

The ever increasing variety of tractors capable of develop- high power has led to the manufacture of improved agricultural machines.

Among these are machines for tilling the soil and preparing it for seed. Such machines having cultivator tools mounted on rotors rotating about substantially vertical axes have become increasingly more popular.

Such known machines are described in several patents, among which is Italian patent No: 616.146 (BOLDRIN). These rotary cultivator machines generally have a box frame on which are mounted substantially vertical contra-rotating, shafts, which are rotatable by gears linked, through a transmission, to a power take-off point on a tractor.

To the lower tip of these contra-rotating shafts is secured a rotor on which are mounted, to depend therefrom, two or more cultivator tools, shaped as tines or blades.

To improve the working of this type of machine, special care must be taken in the design of the cultivator tools which, by acting directly upon the ground, are subject to the maximum wear and stress. Consequently, any improvement made to the cultivator tools improves the efficiency of the whole machine.

Tool stress and wear are particularly noticeable in vertical axes cultivators, such as rotary harrows. Indeed to assure efficient and thorough working of the soil, in these machines the tools are often slightly divergent so that, their trajectories cutting across each other, the soil is thoroughly tilled.

To avoid the problems resulting therefrom, the characteristics these tools should desirably have are quite incompatible. Thus on the one hand their size or thickness should be limited so as not to require too much drive power in the machine, and on the other hand they should be very rugged to resist wear, and at the same time elastic, in order not to be damaged by impact with stones or other obstacles when working.

There is thus a need for a generally improved cultivator tool which, whilst requiring minimum drive power, is sufficiently rugged and elastic enough to withstand shock.

According to the present invention there is provided a cultivator tool having a shank part for attachment thereof to a tool-carrier, a substantially rigid operative part, and a springy elastic intermediate part linking the operative part to the shank part.

Such a tool requires reduced operating drive power and has improved flexibility, working life and working efficiency.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a side view of a cultivator tool according to one embodiment of the invention, Figure 2 is a front view, partially in section, of the tool of Fig. 1, and Figure 3 is a partial top view of a tool of Figs. 1 and 2 attached to a rotor.

A cultivator tool of the invention consists of a shank part for attachment to a tool carrier such as a rotor 6, linked, by a springy elastic intermediate part 2, to a substantially rigid blade 3 which is the operative part of the tool itself. The shank part 1 is substantially rectangular in cross-section, substantially flat and plate-like, being provided with a notch 4 in one end for engagement by a fixed reference element 5, of complementary shape, secured to the rotor 6.

This notch 4 functions properly to position the tool when the same is mounted on a cultivator. The shank part 1 also has a pair of holes 7 therethrough for receiving bolts 8 to secure the tool to the rotor 6 as can be seen in Fig. 3. The intermediate part 2 is an extension of the shank part 1, and is bent in a curved shape through an angle of at least 90" and preferably greater than 90", to have cylindrical inner and outer surfaces.

The intermediate part 2 should have cylindrical surfaces to enable the blade 3 to bend at the intermediate part evenly to distribute the stress over a large surface, and thus avoid breakage. Thus the elastic intermediate part 2 is a sort of spring, having two opposite and offset bending radii R1 and R2. Tests carried out have shown that the optimum radii of the bending radii R1 and R2 are 20 and 25 millimetres respectively for a 30 centimetre long tool, whilst such radii are 14 and 18 millimetres respectively for a 25 centimetre long tool.

The operative part or blade 3 is substantially rectilinear, elongated, and extends from the intermediate part and shank part 1 so as to diverge, when attached to a vertical rotary axis rotor, away from the rotary axis along the length of the blade towards the free tip thereof.

The width of the blade 3 decreases towards the free tip, and the front and rear edges of the blade, with respect to the direction of rotation of the rotor 6, are inclined so that their distance from the longitudinal axis of the blade decreases towards the free tip of the blade 3.

This is a great advantage. In fact, for the tool to be self-cleaning, it is necessary for the operative part thereof to be inclined. Accordingly, it has hitherto been necessary to provide a multiplicity of tools with different angles of inclination depending upon the direction of rotation of the rotors on which they were to be mounted.

On the contrary, the tool according to the present invention can be mounted on rotors rotating either clockwise or anticlockwise, as both its edges are symmetrically inclined with respect to the blade longitudinal axis.

The outer part of blade 3 is provided with a central longitudinal web 9 that extends from the intermediate part 2 to the free tip of the tool blade. This web 9 serves two functions, namely it stiffens the blade making it rugged, and also serves to displace clods of earth just worked, thus avoiding undesirable friction against the outer surface of the blade.

The outer surface of the blade 3 tends to press against the ground during forward movement of the machine, thus wearing more rapidly and absorbing more power by friction.

Tests carried out with tools of the invention showed that with a 25 to 30 centimetre long tool (as generally used in most rotary harrows) the optimum thickness of web 9, for a forward speed of the machine of 5 to 6 km/h, ranged between about 3 mm at the tip end of the blade and 5 to 6 mm at the intermediate part end of the blade 3.

The tool can be made of any material, particularly a Type 55 S18 steel, or spring steel, which proved to be especially suitable.

Claims (9)

1. A cultivator tool having a shank part for attachment thereof to a tool-carrier, a substantially rigid operative part, and a springy elastic intermediate part linking the operative part to the shank part.

2. A tool according to Claim 1, wherein the intermediate part is substantially rectangular in cross-section and bent in a curved shape through an angle of at least 90".

3. A tool according to Claim 1 or Claim 2, wherein the operative part is elongated in form and has front and rear edges, with respect to its operative direction of movement, which are inclined symmetrically with respect to the longitudinal axis of the operative part to allow the tool operatively to be moved in one or other of two opposite directions.

4. A tool according to Claim 3, wherein the elongated operative part is a substantially rectilinear blade provided, on its surface which is outermost in use, with a stiffening central longitudinally extending web.

5. A tool according to Claim 4, wherein the intermediate part which is bent in a curved shape has cylindrical outer and inner surfaces and an axis substantially othogonal to the blade axis.

6. A tool according to any one of Claims 1 to 5, wherein the shank part has a notch for engaging a reference element secured to the tool carrier, for location purposes.

7. A tool according to Claim 4, wherein the distance of the front and rear edges from the blade longitudinal axis decreases towards a free tip of the blade.

8. A tool according to any one of Claims 1 to 7, wherein the operative part, when attached to a tool carrier in the form of a rotor, diverges away from the rotary axis of the rotor along the length of the operative part towards a free tip thereof.

9. A cultivator tool substantially as hereinbefore described, with reference to the accompanying drawings.