EP3298202A1

EP3298202A1 - System for releasable attachment of an excavation tooth

Info

Publication number: EP3298202A1
Application number: EP16796813.0A
Authority: EP
Inventors: Arnold Furre
Original assignee: Komatsu KVX LLC
Current assignee: GH Hensley Industries Inc
Priority date: 2015-05-21
Filing date: 2016-05-11
Publication date: 2018-03-28
Also published as: AU2016264705A1; NO340322B1; EP3298202A4; NO20150647A1; AU2016264705B2; WO2016186510A1

Abstract

A system for the releasable attachment of an excavation tooth (2) to an excavation-bucket element (11), in which a front portion (21) of the excavation tooth (2) projects outwards from a front edge {13} of the excavation-bucket element (11), a mounting hook (221) which projects from a middle portion {22} of the excavation tooth (2) is arranged to grip around a portion of the front edge (113) of the excavation-bucket element (11 ); a rear portion (23) of the excavation tooth (2) is arranged to abut against a side face (111) of the excavation-bucket element (11); and the side face (111) of the excavation-bucket element (11) is provided with a threaded bore (115) arranged to receive a fixing bolt (3) which extends through a bolt hole (24) arranged in the rear portion (23) of the excavation tooth (2) remote from the mounting hook (221), a head (32) on the fixing bolt (3) being provided with a conical abutment portion (321) which is complementary to a conical mouth portion (242) of the bolt hole (24) of the excavation tooth (2).

Description

SYSTEM FOR RELEASABLE ATTACHMENT OF AN EXCAVATION TOOTH

The invention relates to a system for the releasable attachment of an excavation tooth to an excavation-bucket element, in which the front portion of the excavation tooth projects outwards from a front edge of the excavation-bucket element, a mounting hook which projects from a middle portion of the excavation tooth is arranged to grip around a portion of the front edge of the excavation- bucket element, a rear portion of the excavation tooth is arranged to rest against a side face of the excavation-bucket element, and the side face of the excavation-bucket element is provided with a threaded bore arranged to receive a fixing bolt which extends through a bolt hole arranged in the rear portion of the excavation tooth remote from the mounting hook.

On excavator buckets, replaceable excavation teeth are used, which are subjected to abrasion and great strains. The wear on the excavation teeth makes regular replacement of these necessary. Within the technique of today, several types of excavation teeth are known. The most common design is a hollow tooth point that is mounted on a suitable adapter (tooth-holder), and the tooth point is locked to the adapter with a lock pin or a similar locking device. Another type is solid excavation teeth, which are screwed directly to a front piece of the bucket.

Common to the different designs of the excavation teeth is the desire for replacement to be quick and simple and preferably be feasible without the use of a hammer ("hammer!ess"). It is also desirable for as much material as possible to have been worn away before the excavation tooth has to be replaced. The fixing bolts of screwed excavation teeth are often large when the fixing bolts are to absorb the excavation forces directly. The fixing bolts then require great torques which, in turn, lead to a requirement for costly and, in part, heavy torquing equipment.

From WO 2009082317 A1 a wear part for a bucket for a loading or digging machine is known, the bucket being provided with a front plate, to which the wear part is attached, there being a hook portion resting against a forward chamfer on the front plate, and an attachment portion of the wear part extending rearwards along the front plate. The attachment portion is provided with a cut-out for a head of a fixing bolt which extends with a threaded shaft through a bore in the front plate to a nut resting against a bottom surface in a recess in the front plate. The head of the fixing boit has a rectangular cross section and is provided with two opposite end faces converging in the direction of the threaded shaft of the bolt. One slanted side face is arranged to rest against a corresponding rear, sloping surface in the recess of the mounting portion, said recess being offset relative to the bore of the front plate, or said bolt head being asymmetrical to the bolt shaft, and, when the nut is tightened, the wear part is pushed rearwards so that the hook portion is pressed against the forward chamfer of the front plate. The nut is arranged in a recess in the front plate.

US3197894 A discloses a wear-tooth assembly in which a replaceable wear point is releasably attached to a conical holder, which, in turn, is rigidly secured to a sloping front edge (lip) of an excavation bucket or the like. The holder has a hook portion, which grips around the front chamfer, and a rear portion, which rests against a surface of the bucket. The wear point is attached to the holder by set screws with rounded or tapered end portions being screwed into threaded holes in the side walls of the wear point into abutment against a side edge in a recess or a through bore in the holder in order thereby to press the wear point onto a conical front portion of the holder.

US5553409 A discloses a system for shielding a front edge of an earth-moving implement, typically a loading bucket, from wear, in which hook-shaped shrouds are arranged between the excavation teeth and enclose the front edge between the excavation teeth. Each shroud extends to the rear of the excavation teeth and is attached to a bracket fixed to the excavation bucket, as a slanted end face of the shroud is resting against a corresponding shoulder on the bracket and the shroud is fixed by means of a pin inserted into a transverse passage in the bracket and the shroud.

From W019509950 A1 , a system for attaching an excavation tooth is known, in which, in an oblong hole in a front plate, a rectangular stop is arranged, projecting from the hole. An upper excavation- tooth portion extending in over the upper side face of the front plate is provided with a through ob- long cut-out for receiving the upper end portion of the stop. A lower excavation-tooth portion extending in over the lower side face of the front plate is provided with an oblong slot for receiving the lower end portion of the stop. The excavation tooth is locked by a locking piece being inserted into the cut-out into engagement in a recess in the rear end wall of the cut-out, and a key is inserted into the gap between the Socking piece and the stop. The key is locked by means of a locking plate, which is attached to the top of the locking piece, engaging with a toothed side edge of the key.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.

The object is achieved through the features, which are specified in the description be!ow and in the claims that follow. Even though, in what follows, terms that are used in connection with excavator buckets are used, the invention is not limited to applying only to such use, but may also be used on buckets for other types of earth-moving implements, for example on loading buckets for wheel loaders and so on.

The invention provides an excavation tooth in which a middle portion is provided with a projecting mounting hook, which is arranged to grip around a portion of a front edge of an excavation bucket. A rear portion of the excavation tooth rests against a side face, typically a plane bottom face, of the excavation bucket and, in the rear portion, remote from the mounting hook, a fixing bolt is arranged, extending through a bolt hole in the mounting hook and into a corresponding bore in said side face. Preferably, the fixing bolt has a conical abutment portion, which is arranged to rest against a corresponding, conical portion in the mouth of the bolt hole of the excavation tooth. The bore in the side face of the excavation bucket is preferably threaded.

By the engagement of the mounting hook with the front edge of the excavation bucket, a force component with a direction that is perpendicular to the front edge of the excavation bucket will be transmitted to the bucket through the mounting hook.

The excavation tooth is provided with means for absorbing a force component that is parallel to the front edge of the excavation bucket, if is an advantage if such lateral stabilization is formed as a recessed seat in the front edge of the excavation bucket with a width corresponding to the width of a projecting end portion of the mounting hook and is arranged to form a lateral support for said end portion. Further lateral stabilization may be provided in the form of a locking element, typically a key, which is arranged in coinciding recesses in said side face of the excavation bucket and in an adjacent side face of the rear portion of the excavation bucket.

Preferably, the centre axis of the bolt hole of the excavation tooth lies somewhat closer to the front edge of the excavation bucket than the bore of the side face of the bucket does. When a fixing bolt with a conical abutment portion and a conical mouth portion in the bolt hole of the excavation tooth are used, such an offsetting of the bolt hole will result in the screwing-in of the fixing bolt generating an inward displacement of the excavation tooth on the excavation bucket with the result that any play between the mounting hook of the excavation tooth and the front edge of the excavation bucket is eliminated.

By the very fact of the excavation tooth's being attached to the excavation bucket by means of the mounting hook, the fixing bolt will, in the main, be stressed only by force components subjecting the excavation tooth to a rotation around the abutment of the excavation tooth against the front edge of the excavation bucket. For a certain load dimensioning, by using a relatively large distance between the front edge of the excavation bucket and the fixing bolt, a fixing bolt of a considerably smaller dimension than in excavation teeth with an ordinary arrangement with two or more fixing screws may be used. What is decisive for the strength of the attachment of an excavation tooth according to the invention is the dimensioning of the mounting hook and the dimension of the cross section of the excavation tooth in the transition between the rear portion and the mounting hook, that is to say the cross-sectional size right opposite the front edge of the excavation bucket, where the bending stress is greatest. The invention is defined by the independent claim. The dependent claims define advantageous embodiments of the invention.

The invention relates, more specifically, to a system for the reieasable attachment of an excavation tooth on an excavation-bucket element, in which a front portion of the excavation tooth projects outwards from a front edge of the excavation-bucket element,

a mounting hook which projects from a middle portion of the excavation tooth is arranged to grip around a portion of the front edge of the excavation-bucket element; and

a rear portion of the excavation tooth is arranged to abut against a side face of the excavation-bucket element;

the side face of the excavation-bucket element is provided with a bore arranged to receive a fixing bolt which extends through a bolt hoie arranged in the rear portion of the excavation tooth remote from the mounting hook, characterized by

a head of the fixing bolt being provided with a conical abutment portion which is complementary to a conical mouth portion of the bolt hole of the excavation tooth, and

a centre axis of the bolt hole exhibiting a smaller distance to the front edge of the excavation-bucket element than the distance between a centre axis of the bore and the front edge of the excavation-bucket element when the excavation tooth is attached to the excavation-bucket element.

The side face of the excavation-bucket element may form a portion of an external side face of the excavation bucket. An advantage of this is that the load on the fixing bolt from break-out force, to which the excavation tooth is subjected by norma! filling of the excavation bucket, is largely eliminated.

At least part of a projecting end portion of the mounting hook may engage with a recessed seat portion at the front edge of the excavation-bucket element. An advantage of this is that the excava- iion tooth is prevented from being displaced sideways when subjected to a force component parallel to the front edge of the excavation-bucket element.

There may be corresponding grooves arranged in the side face of the excavation-bucket element and in an adjacent abutment surface of the rear portion of the excavation tooth, arranged to accommodate a locking element, typically in the form of a key. An advantage of this is that the load on the fixing bolt caused by a torque generated by a force component parallel to the front edge of the excavation-bucket element is reduced considerably.

At least one of the grooves may exhibit a length, which allows displacement of the locking element in the iongitudinai direction of the excavation tooth. An advantage of this is that the locking element does not prevent the fixing bolt from pulling the mounting hook towards the front edge of the exca- vation-bucket element on its abutment against the rear portion of the conical mouth portion of the bolt hole. A front recess adjacent to the recessed seat portion may break through the front edge of the excavation-bucket element and be arranged to receive a complementary abutment portion arranged at the mounting hook of the excavation tooth. An advantage of this is that the lateral stability of the excavation tooth is improved.

The front recess may be defined by opposite side faces, which converge in a direction away from the recessed seat portion. This gives a further improvement of the lateral stability of the excavation tooth. Besides, the abutment of the abutment portion against the converging side faces of the recess will result in the excavation tooth being held in position even if the mounting hook has disappeared because of wear or breakage.

In what follows, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which:

Figure 1 shows a detail of a front piece of an excavation bucket viewed from above, where an excavation tooth according to the invention has been attached;

Figure 2 shows a detail of the front piece and the excavation tooth viewed from below;

Figure 3 shows a detail of the front piece with attachment details for an excavation tooth, not shown, in the form of a mounting-hook seat, a bolt hole and a locking-element groove;

Figure 4 shows a longitudinal section in the vertical centre plane of the excavation tooth and the front piece;

Figure 5 shows a detail of figure 4 on a larger scale;

Figure 6 shows a detail of the front piece with an alternative embodiment of a mounting- hook seat; and

Figure 7 shows an end view of the excavation tooth viewed from behind.

In the figures, the reference numeral 11 indicates an excavation-bucket element, which forms a front edge 113 on an excavation bucket. Said excavation-bucket eiement 11 is also referred to as a front piece by persons skilled in the art and is often replaceable.

The excavation-bucket element 11 has external and internal side faces 111 and 112, respectively, the internal side face 112 constituting a portion of the combined side faces defining the volume of the excavation bucket, and the external side face 111 facing outwards towards the surroundings of the excavation bucket.

A replaceable excavation tooth 2 comprises a front portion 21, also called a point, a middle portion 22 and a rear portion 23. The middle portion 22 is provided with a mounting hook 221 with an opening facing away from the point 21 of the excavation tooth 2 and being arranged to grip around a portion of the front edge 113 of the excavation-bucket eiement 11. In said front edge 113, a recessed mounting-hook seat 114 is formed, which is arranged to at ieast partially accommodate a projecting hook portion 221 a and iateraliy fix the mounting hook 221 on the front edge 113 of the excavation- bucket element 11.

The rear portion 23 of the excavation bucket 2 extends along the external side face 111 of the excavation-bucket element 11 as an abutment surface 232 rests supportingly against said side face 111. Near an end portion 231 of the excavation tooth 2, a boit hole 24 is arranged with a centre axis 241 substantialiy perpendicular to said abutment surface 232. The boit hoie 24 is provided with a conical mouth portion 242.

The excavation-bucket element 11 is provided with a threaded bore 115 with a centre axis 116 substantially perpendicular to the external side face 111 of the excavation-bucket element 11. The bore 115 is arranged to receive a fixing bolt 3 extending through the boit hoie 24 of the excavation tooth 2. A bolt head 32, which is provided with engagement portions 322 for a tightening tool {not shown) in a manner known per includes a conical abutment portion 321 which is complementary to the conicai mouth portion 242 of the bolt hole 24. A threaded portion 31 of the fixing bolt 3 is arranged to engage with the threaded bore 115 of the excavation-bucket eiement 11.

The centre axis 116 of the bore 115 is arranged at a distance from the front edge 113 of the exca- vation-bucket element 11. The bolt hoie 24 is arranged in such a way that the bolt-hole centre axis 241 is closer by a distance a (see figure 5) to the front edge 113 than the bore centre axis 116 is when the mounting hook 221 of the excavation tooth 2 is in engagement with the mounting-hook seat 114 of the front edge 113.

In the exemplary embodiment shown (see figures 4 and 5 in particular), between the bore 115 and the front edge 113, a keyway 118 is arranged in the external side face 111 , being arranged, together with a corresponding locking-element groove 25 arranged in the abutment surface 232 of the excavation tooth 2, to receive a locking element 4, typically a so-called key. At least one of the locking-element grooves 118 and 25, respectively, has an extent in the longitudinal direction of the excavation tooth 2 larger than the length of the locking element 4. in figure 6, an alternative exemplary embodiment of the mounting-hook seat 114 is shown, extended here by a front recess 114a breaking through the front edge 113 of the excavation-bucket element 11 and being provided with opposite side faces 114b. The side faces 114b converge in a direction away from the mounting-hook seat 114 by an angle A between them. In a preferred embodiment, the angle A is 10;^'j A complementary abutment portion 221 b adjacent to the mounting hook 221 of the excavation tooth 2 is arranged to rest supportingly with converging side faces 221c against the side faces 114b of the front recess 114a when the projecting hook portion 221a is rest- ing in the mounting-hook seat 114.

The excavation tooth 2 is attached to the excavation-bucket element 11 by the mounting hook 221 being brought into engagement with the mounting-hook seat 114. The abutment surface 232 of the rear portion 23 is brought into abutment against the externa! side face 111 of the excavation-bucket element 11. The fixing bo!t 3 is inserted into the bolt hoie 24 and screwed into the bore 115 until the conical abutment portion 321 abuts against the conical mouth portion 242 of the bolt hoie 24. Because of the centre axes 118 and 241 of the bore 115 and bolt hoie 24, respectively, having a distance a in the !ongitudinal direction of the excavation tooth 2, the conical abutment portion 321 of the fixing bolt 3 will abut against a rear edge 242a {see figure 5) of the conical mouth portion 242 and thereby push the excavation tooth 2 rearwards. Any play in the abutment between the mounting hook 221 and the mounting-hook seat 114 is thereby eliminated and the connection between the excavation-bucket e!ement 11 and the excavation tooth 2 is tensioned.

St is an advantage that the rear portion 23 of the excavation tooth 2 is resting against the externa! side face 11 1 of the excavation-bucket element 11. In normal excavation operations, the excava- tion tooth 2 will transmit so-called positive break-out force to the excavation-bucket element 11 via the mounting hook 221 and the abutment of the rear portion 23 against the excavation-bucket element 11. The fixing bolt 3 will be stressed first and foremost by so-called negative break-out force, that is to say when the excavation bucket is pushing mass instead of penetrating into the mass and filling. The fixing bolt 3 is subjected to shear forces when the excavation tooth 2 is subjected to a force component, which is parallel to the front edge 113. The use of locking-element grooves 118, 25 and a key 4 reduces this stress on the fixing bolt 3 as the torque is then absorbed by the locking element 4.

By a large distance being used between the bore 115 and the front edge 113, the size of the fixing bolt 3 may be reduced, as the force that is to be transmitted through the fixing bolt 3 decreases with increasing length of the torque arm for torque around the rotational axis which is formed at the interface between the mounting hook 221 and the front edge 113 of the excavation-bucket element 11.

Wear on the excavation tooth 2 results in a change in the contour of the excavation tooth 2. Based on experience, the excavation tooth 2 may reach a contour 28 before it will have to be replaced. A critical size for the strength of the excavation tooth 2 is the cross-sectionai sizes indicated by the reference numerals 222 and 222a in figure 4.

The use of the verb "to comprise" and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article "a" or "an" before an el- ement does not exclude the presence of several such elements. The fact that some features are indicated in muiually different dependent claims does not indicate that a combination of these features cannot be used with advantage.

Claims

C l a i m s

1. A system for the releasabie attachment of an excavation tooth (2) to an excavation- bucket eiement (11), in which a front portion (21) of the excavation tooth (2) projects outwards from a front edge (13) of the excavation-bucket eiement (11), a mounting hook (221) which projects from a middie portion (22) of the excavation tooth (2) is arranged to grip around a portion of the front edge (113) of the excavation-bucket element (11), a rear portion (23) of the excavation tooth (2) is arranged to abut against a side face (111) of the excavation-bucket eiement (11), and the side face (111) of the excavation-bucket eiement (11) is provided with a threaded bore (115) arranged to receive a fixing boit (3) which extends through a bolt hole (24) arranged in the rear portion (23) of the excavation tooth (2) remote from the mounting hook (221), c h a r a c t e r i z e d i n that

a head (32) on the fixing bolt (3) is provided with a conicai abutment portion (321) which is complementary to a conicai mouth portion (242) of the bolt hole (24) of the excavation tooth (2), and

a centre axis (241) of the bolt hole (24) exhibits a smaller distance to the front edge (113) of the excavation-bucket element (22) than the distance between a centre axis (116) of the bore (115) and the front edge (113) of the excavation-bucket element (11) when the excavation tooth (2) is attached to the excavation-bucket element (11).

2. The system according to claim 1 , wherein the side face (111 ) of the excavation-bucket element (11) forms a portion of an external side face of the excavation bucket.

3. The system according to claim 1 , wherein at least part of a projecting end portion (221a) of the mounting hook (221) engages with a recessed seat portion (114) at the front edge (113) of the excavation-bucket eiement (11).

4. The system according to claim 1 , wherein corresponding grooves (118, 25) are arranged in the side face (111 ) of the excavation-bucket element (11) and in an adjacent abutment surface (232) on the rear portion (23) of the excavation tooth (2) and is arranged to accommodate a locking element (4).

S The system according to claim 4, wherein at least one of the grooves (118, 25) exhibits a length, which allows displacement of the locking element (4) in the longitudinal direction of the excavation tooth (2).

6. The system according to claim 3, wherein a front recess (114a) adjacent to the recessed seat portion (114) breaks through the front edge (113) of the excavation-bucket element (11) and is arranged to receive a comp!ementary abutment portion (221b) arranged at the mounting hook (221) of the excavation tooth (2).

7. The system according to c!aim 8, wherein the front recess (114a) is defined by opposite side faces (114b) converging in a direction away from the recessed seat portion (114).