EP1554436B1

EP1554436B1 - Anchoring of a wear element to a bucket front

Info

Publication number: EP1554436B1
Application number: EP03751624A
Authority: EP
Inventors: Tor Torgrimsen
Original assignee: Komatsu KVX LLC
Current assignee: Komatsu KVX LLC
Priority date: 2002-10-02
Filing date: 2003-09-30
Publication date: 2013-03-20
Anticipated expiration: 2023-09-30
Also published as: AU2003269729B2; NO20024725D0; WO2004031494A1; AU2003269729A1; NO318005B1; EP1554436A1

Description

This invention relates to a single bolt excavating tooth-securing element for employment on the share- or bucket front of earth-moving machines. More specifically, it concerns a removable excavating tooth securing element, where the fastening bolt of the securing element is only exposed to tensile forces in its working position.
Exchangeable excavating teeth can be connected to the share-or bucket front by means of e.g. a bayonet connection, US patent 1.419.047 shows such a solution, or by means of at least two bolts, where one embodiment appears in US patent 4.108.250 .
It is also known to connect a reversible excavating tooth to a flat bucket front by means of two pre-stressed bolts, or by means of a bolt and a locking pin such as is shown in GB 22 51 641 , this document forming the basis for the preamble of the independent claims. US 4.056.893 discloses an adapter for detachably mounting teeth at the cutting edge of a bucket loader. The adapter engages with the cutting edge via mating between a projection and a recess to ensure correct alignment of the adapter during securement to the bucket loader.
The employment of reversible excavating teeth has proven to be economically advantageous in that excavating teeth of this type are equipped with two wear parts. When one wear part is worn out, the excavating teeth can be reversed, after which the other wear part can be employed.
The pre-stressed bolts that are arranged to press the abutment surface of the excavating tooth against the bucket front, are according to prior art relatively short. The pre-stressed bolts are therefore provided with a function which is equivalent to a stiff spring with little drift. The pre-stressed bolts can therefore only to a minor degree absorb distance changes between the abutment surfaces in the tensile direction of the bolts. This relationship presupposes that the abutment surfaces of the excavating teeth and the bucket front must be exactly fitted to each other, for example by means of machining.
Experience shows that the friction forces between the excavating tooth and the bucket front during the relatively rough treatment an excavating tooth is exposed to, are not sufficient to resist the forces which arise in directions parallel with the plane of attachment. Thus, the pre-stressed bolts must also be able to absorb considerable shear and bending forces, according to prior art.
Those in the pre-stressed bolts occurring loads are difficult to calculate, and this undefined load-effect means that the pre-stressed bolts must be dimensioned using a higher load safety factor to prevent the excavating teeth from loosening. Bolt mounted excavating teeth, according to prior art, are therefore unnecessarily large and heavy due to extra material between the bolts.
The object of the invention is to remedy the disadvantages of the prior art.
This object is achieved according to the invention, and by means of the features disclosed in the description below, and in the following patent claims.
By constructing the excavating tooth securing element such that the excavating tooth is connected to the bucket front by means of one pre-stressed bolt which is approximately perpendicular relative to the plane of attachment, below denoted bolt, where the bolt in its working position substantially is exposed to tensile force only, the forces which affect the bolt and the rest of the securing element are moreover defined in an essentially more secure way, relative to prior art.
According to the invention the forces which work parallel to the plane of attachment between the excavating tooth and the bucket front, and also the torque along the longitudinal axis of the bolt, are absorbed by cams which protrude from one part and into the corresponding recesses in the other part, for example from the excavating teeth and into the bucket front. Alternatively, the cams can be formed by separate or jointed bodies which protrude into the corresponding recesses both in the excavating tooth and the bucket front.
Thus viewed from one aspect the present invention provides a share- or bucket front arrangement of an earth moving machine, the arrangement comprising: an excavating tooth or an adapter for an excavating tooth for attachment to the bucket front, the tooth or adapter comprising a surface for positioning opposed to a surface of the bucket front;
the arrangement characterised by:
at least one cam for extending between the opposed tooth or adapter and the bucket front so as to create a clearance between the surface of the excavating tooth or adapter and the bucket front to form a support for a bolt bridge, the bolt bridge configured to receive a single bolt to secure the tooth or adapter at the bucket front.
Viewed from a further aspect the present invention provides a share- or bucket front arrangement of an earth moving machine, the arrangement comprising: an excavating tooth or an adapter for an excavating tooth for attachment to the bucket front, the tooth or adapter comprising a surface for positioning opposed to a surface of the bucket front;
the arrangement characterised by further comprising:

at least one cam which is formed by a body separate from the excavating tooth or adapter and the bucket front wherein the body protrudes into and bottoms in corresponding recesses in the bucket front and the excavating tooth or adapter so as to create a clearance between the surface of the excavating tooth or adapter and the bucket front to form a support for a bolt bridge, the bolt bridge configured to receive a single bolt to secure the excavating tooth or adapter at the bucket front.

In a preferred embodiment, the cams are semi-spherical, where at least three cams are placed at a suitable radial distance from the bolt. For reversible excavating teeth, it is preferable that four cams are employed in each excavating tooth.
The protruding length of each cam is adapted such that the cam bottoms in its complementary recess. The excavating tooth surface surrounding the cams thus does not rest on the bucket front.
When the bolt is pre-stressed and the excavating tooth is pulled down towards the bucket front, the material of the excavating tooth surrounding the bolt is also provided with a bending stress. Compared with a bolt connection where the abutment surfaces, also before pre-stressing, rest on each other, the embodiment according to the invention forms a "softer" connection, in that both bolt and the material of the tooth are pre-stressed and are arranged to absorb less changes in distance between the excavating tooth and the bucket front in the longitudinal direction of the bolt.
Due to the definable load pattern which works on the different parts of the excavating tooth securing element, the dimensions of the securing part of the excavating tooth can be reduced relative to excavating teeth according to prior art. An excavating tooth according to the invention has smaller structural dimensions and, at the same time, fitting and replacement work is considerably simplified.
In the following, a non-limiting example of a preferred embodiment is described, and is illustrated in the accompanying drawings, in which:

Figure 1 shows reversible excavating teeth which are mounted to the underneath of the bucket front;
Figure 2 shows a section I-I in figure 1;
Figure 3 shows a section I-I in figure 1, but here the cams are formed by separate bodies;
Figure 4 shows a the front part of the excavating bucket seen from above where adapters and excavating teeth are fitted; and
Figure 5 shows in perspective and partly in section an adapter and a excavating tooth according to figure 4.

On the drawings the reference number 1 represents a reversible excavating tooth which is secured to the bucket front 4 of an excavating bucket 2 by means of a pre-stressed bolt 6 and four cams 8. The bolt 6 is screwed into the corresponding threads 7 in the bucket front 4.
The cams 8 protrude from the surface part 10 of the excavating tooth 1 and faces towards the bucket front 4 and into the corresponding recesses 12 in the bucket front 4. The cams 8 are designed such that they bottom in the recesses 12. The surface part 10 has therefore, both before and after the bolt 6 is tightened, a clearance to the bucket front 4, and forms therefore, together with a part of the excavating tooth 1, a bolt bridge 11 which is provided with a countersunk through bore 13 for the bolt 6.
The cams 8 in the figures are substantially semi-spherical. It has been shown that this geometry is advantageous in that the half sphere, when it is placed in its respective recess 12, gives a steady anchorage where the connection exhibits a good ability to absorb the occurring forces.
When the bolt 6 is tightened, the bolt 6 is pre-stressed at the same time as the bolt bridge 11 of the excavating tooth 1 is provided with a bending stress. The bending stress arises in that the tensile force of the bolt 6 seeks to displace the surface part 10 around the bolt 6 in towards the bucket front 4, while the cams 8, which bottoms in their recesses 12, form supports for the excavating tooth 1.
This somewhat resilient fixing causes the connection between the excavating tooth 1 and the bucket front 4, compared with prior art, to have a greater possibility to absorb reciprocal distance changes between the excavating tooth 1 and the bucket front 4 in the axial direction of the bolt 6, without the pre-stress of the bolt 6 being reduced to an unwanted degree.
In figure 3 the cams are replaced with bodies 14 which protrude into to the recesses 12 in the bucket front 4 and in to the corresponding recesses 16 in the excavating tooth 1.
In an alternative embodiment, see figure 4, an excavating tooth 18 is connected to a bucket front 20 by means of an adapter 22. The excavating tooth 18 is attached to the adapter 22 by means of a slot and a bolt in a manner known per se.
The adapter 22 is secured to the bucket front 20 in a manner corresponding to that described for the reversible excavating tooth 1, but here three cams 8 and corresponding recesses 12 are employed.
The shape of the cams 8 can take any suitable form where the form causes a bolt bridge 11 to be created, and where the bolt 6 tightens against the bridge between the supports of the bridges. For example, one non-circular cam which encircles the bolt 6 at a radial distance from the bolt 6, can also form a cam according to the invention.
The construction according to the invention, where the cams are designed to absorb forces and moment which work parallel to the surface 10 of the excavating tooth 1, while the bolt 6 absorbs forces which work perpendicular to the surface 10, making it possible for the appearing forces to be transferred to the element which absorbs the forces or components of forces in a significantly more secure way relative to prior art.
Experiments have shown that an excavating tooth 1 which is connected to the bucket front according to the invention, is considerably less prone to loosen during operation than screwed on excavating teeth according to prior art.

Claims

A share- or bucket front (4, 20) arrangement for an earth moving machine, the arrangement comprising:
an excavating tooth (1) or an adapter (22) for an excavating tooth (1) for attachment to the bucket front (4, 20), the tooth (1) or adapter (22) comprising a surface (10) for positioning opposed to a surface of the bucket front (4,20);

the arrangement characterised by:
at least one cam (8) for extending between the opposed tooth (1) or adapter (22) and the bucket front (4, 22) so as to create a clearance between the surface (10) of the excavating tooth (1) or adapter (22) and the bucket front (4, 20) to form a support for a bolt bridge (11), the bolt bridge (11) configured to receive a single bolt (6) to secure the tooth (1) or adapter (22) at the bucket front (4, 20).
An arrangement according to claim 1, characterised in that the cam (8) is secured to the excavating tooth (1) and protrudes into and bottoms in a corresponding recess (12) in the bucket front (4).
An arrangement according to claim 1, characterised in that the cam (8) is secured to the bucket front (4) and protrudes into and bottoms in a corresponding recess (16) in the excavating tooth (1).
A share- or bucket front (4, 20) arrangement for an earth moving machine, the arrangement comprising:
an excavating tooth (1) or an adapter (22) for an excavating tooth (1) for attachment to the bucket front (4, 20), the tooth (1) or adapter (22) comprising a surface (10) for positioning opposed to a surface of the bucket front (4,20);

the arrangement characterised by further comprising:
at least one cam which is formed by a body (14) separate from the excavating tooth (1) or adapter (22) and the bucket front (4, 20) wherein the body (14) protrudes into and bottoms in corresponding recesses (12, 16) in the bucket front (4, 20) and the excavating tooth (1) or adapter (22) so as to create a clearance between the surface (10) of the excavating tooth (1) or adapter (22) and the bucket front (4,20) to form a support for a bolt bridge (11), the bolt bridge (11) configured to receive a single bolt (6) to secure the excavating tooth (1) or adapter (22) at the bucket front (4, 20).
An arrangement according to one or more of the preceding claims, characterised in that a pre-stressed bolt (6) protrudes through the bolt bridge (11) and into complementary threads (7) in the bucket front (4, 20).