GB2157650A

GB2157650A - Wear part for earth working tooth

Info

Publication number: GB2157650A
Application number: GB08509982A
Authority: GB
Inventors: Kjell Mohlin; Ove Nilsson
Original assignee: Bofors Wear Parts AB
Current assignee: Bofors Wear Parts AB
Priority date: 1984-04-18
Filing date: 1985-04-18
Publication date: 1985-10-30
Also published as: DE3513670A1; FR2563254B1; ES8607456A1; JPS60233236A; GB8509982D0; FR2563254A1; DE3513670C2; SE456097B; IT1181639B; CA1253906A; SE8402155L; SE8402155D0; ES542377A0; GB2157650B; ZA852753B; AU4136385A; IT8547966A0; JPH0663268B2; IT8547966A1; AU572644B2

Abstract

A wear part for a tool for an earth-working machine comprises a front tooth tip (6) which, in the fitted condition, protrudes beyond the front edge of the tool (2) in its working direction and which includes a female part (11) facing rearwards in the working direction and cooperating with a corresponding, forwardly protruding male part (3) of an adapter (2), attached to the tool or forming an integral part of the front edge of the tool, and to which the tooth tip is releasably attached by a locking element (5). The male and female parts provide support surfaces facing in different directions and adapted to contact each other. The male part provides at least two support surfaces (8 and 24) disposed each in its own plane at a distance from each other and which in use to face towards the surface of the earth being worked, and the female part provides a corresponding number of oppositely facing support surfaces (12 and 25) adapted to contact the support surfaces of the male part. Should the tip become worn at its bottom face so that surface (8) no longer exists, the tip is retained on the adaptor by contact between surfaces (24, 25). <IMAGE>

Description

SPECIFICATION Wear part for a tool for an earth-working machine.

This invention relates to an improved wear part for tools for earth-working machines such as excavators, loaders, mechanical shovels, etc. More specifically, the invention provides a special design for the so- called cap teeth of such wear parts. The object of the invention is to reduce the risk of the teeth concerned from becoming loose and falling off from the adapters to which they are releasably attached when they have become worn out. This is in fact frequently a major problem, expecially when the machines are used to load directly down into crushers, where a tooth falling into the crushing material can result in major damage to the crushers.Another problem which can occur is that the loss of a tooth which is not promptly observed by the machine operator can rapidly lead to the tooth adapter becoming irreparably damaged through continued working with the tool without replacement of the lost tooth.

The invention relates, as mentioned above, to cap teeth. In teeth of this kind, the replaceable tooth tip is designed with a female part or recess extending rearwards in the working direction of the tool and which receives a forwardly protruding male part which constitutes the front part of the tooth adapter in the working direction and to which it is releasably attached by means of a locking element. The tooth adapter may in turn be attached to the tool by means of its own locking member or it may comprise an integrae portion of the leading edge of the tool. Cap teeth are highly economical in term of material consumption since they can be worn down until only very little material remains.The tooth should nevertheless be replaced before the lower portions of the female part have been completely worn away, since the tooth tip then normally loses its grip on the male part and falls off.

According to the present invention, a new design is provided whereby the male part of the adapter is provided with at least two support surfaces disposed each in its own plane at a distance from each other facing towards the worked earth surface, while the female part of the respective tooth tip is provided with a corresponding number of support surfaces for contact against the said support surfaces in the male part and which thus face away from the worked earth surface.

According to the preferred embodiments of the invention it becomes possible to completely wear down the lower portions of the female part of the tooth tip without the tooth tip falling off, but at the same time the machine operator is given advance warning about what is happening in that the tooth tip starts to play on the adapter, something that any competent machine operator cannot fail to observe when working with his machine.

One of the support surfaces of the male part facing towards the worked earth surfaces consists appropriately of the bottom surface of the male part, whereas other support surfaces facing in the same direction may consist of a support surface disposed farthest along on the male part which is located at a somewhat greater distance from the said earth surface. In an alternative embodiment the male part has a T-shaped cross section with calluses protruding towards the side, where the bottom of the male part comprises one of the support surfaces while the other support surfaces comprise the under surfaces of the respective calluses.

The female part of the tooth tip or cap is shaped so that it provides corresponding but counterdirected support surfaces. If the bottom of the tooth tip, i.e. the cap, is completely worn away, the support surface of the tooth tip resting against the underside of the male part will be entirely eliminated, but the other support surface or surfaces will still act to keep the tooth in place.

In order to call the attention of the machine operator to the development of undue wear in the tooth tip or cap and interacting support surfaces in the male part and female part located closest to the worked earth surface can be elaborated with the least possible play between them, whereas a sufficiently large amount of play is purposely provided between the remaining interacting support surfaces in order for the tooth tip, when its lower portions have been completely worn away, to rattle thoroughly on its adapter without loosening and dropping off on that account.

Embodiments of the invention will now be described in greater detail and with reference to the accompanying figures, of which Figure 1 shows a partly sectioned longitudinal projection of a tooth according to the invention, Figure 2 shows a partly sectioned perpendicular view of Fig. 1, Figure 3 shows the same projection as Fig. 1 but with the tooth tip in a severely worn stage, Figure 4 shows a partly sectioned longitudinal view of another varient of the invention, while Figure 5 shows a partly sectioned perpendicular view of Fig. 4 and Figure 6 shows sections VI-VI in Fig. 4.

Shown in Fig. 1-3 is a tooth adapter 1 which is welded to the front bottom edge 2 of a bucket. The tooth adapter 1 displays a male part 3 protruding forwards in the working direction of the bucket. On the top of the male part is a locking groove 4 in which a locking element 5 is disposed. The locking element 5 can be elaborated in several different per se known manners. Its main function is to keep the tooth tip 6 secured to the adapter 1. In order to make the figures as simple and distinct as possible, no details of the locking element have been included in the figures.

The male part 3 of the adapater 2 narrows off forwards in the working direction of the bucket and displays a lower bottom surface 8 which, when the bucket is at work, faces towards the earth surface being worked. The male part also has an upper surface 7 and tooth side surfaces 9 and 10. The previously mentioned locking groove 4 is disposed in the upper surface 7.

The tooth tip 6 is in the shape of a cap which is passed over the male part 3. For this reason, the tooth tip 6 is designed with a female part or recess 11 expanding rearwards in the working direction.

This female part 11 displays a first support or bottom surface 12 adapted for contact against the bottom surface 8 of the male part, a second support or upper surface 13 for contact against the upper surface 7 of the male part, and additional supports or side surface 14 and 15 respectively of the male part. In addition, the tooth tip has two rearwards protruding overhangs 16,17, for which grooves 18, 19 are provided in the adapter. In front of the overhang is a locking groove 20 as a complement to the locking groove 4 in the male part 3. The locking element 5 fills out the space between these two locking grooves and thus locks the tooth tip 6 to the adapter 1. Two openings 21 and 22 adapted to the locking grooves and through which the locking element 5 can be removed or fitted are provided in the tooth tip.

The male part 3 is terminated in the forward direction by a callus or nose 23 which displays a lower support surface 24 facing towards the earth surface being worked and which is situated farther away from the earth surface than the bottom surface 8. As evident from the figures, the female part is also adapted to the nose 23 by means of a bottom surface 25 facing towards the support surface of the latter. As evident from Fig. 1, there is nor mally a clearance between the bottom surface 25 of the nose 23 and the second (upper) bottom surface 24 of the male part. If the tooth tip 6 is com pletely worn down so that the bottom surface 12 of the female part is entirely eliminated the stage shown in Fig. 3 is reached. The two support surfaces 24 and 25 will then interact and prevent the tooth tip 6 from falling off which would otherwise occur.The play a nevertheless causes the tooth to rattle so much in its attachment that the attention of the machine operator is called to the necessity of changing the tooth tip. In Fig. 3, the original shape of the tooth tip is marked with broken lines.

In addition the possibilities of the remaining tooth tip to play on the adapter are marked with both fully drawn and dotted lines.

The variant of the invention shown -in Figs 4-5 agrees in essentials with the variant illustrated in Fig. 1-3, apart from the fact that the nose 23 of the male part has been replaced by two calluses 26 and 27 disposed on either side of the male part 29 of the adapter 28. The calluses 26 and 27 each re veal a support surface 30 and 31 respectively fac ing towards the earth surface being worked which is located further away from the earth surface and the bottom surface 32 of the male part 29. The cal luses 26 and 27 impart to the male part a T-shaped cross-section (see Fig. 5).The female part 34 of the tooth tip 33 has the same T-shaped cross-section with a main bottom surface 35 designed for con tact against the main bottom surface 32 of the male part, and grooves 36 and 37 ih which are dis posed support surfaces 38 and 39 for contact against the support surfaces 30 and 31 on the cal luses of the male part. In addition, the male part has two side surfaces 40, 41 for guidance of the tooth tip laterally through contact against the side surfaces 42 and 43 respectively of the male part.

Other details shown in Fig. 4-6 such as the overhangs 16 and 17, grooves 18, 19 adapted thereto, the upper sides 7 and 13 of the male and female parts respectively, and the locking element 5 and associated locking grooves etc. have the same reference numerals as in Fig. 1- 3, since these items are identical.

The contact between the main bottom surfaces 35 and 32 in the male and female parts respectively should be free of play, as should the contact between the upper side 7 of the male part and the opposing contact surface 13 of the female part, as well as the side surfaces 40, 41 and 42, 43 respectively.

In contrast, a certain minor amount of play may be appropriate between the support surfaces 30, 38 and 31, 39 respectively. This implies that when it is worn out the tooth tip 33 will play on the adapter 28 without being able to fall out on that account.

(Compare the distance a in Fig. 1.) The extra support surfaces are appropriately located within areas with small bending stresses, e.g. in the proximity of the middle plane of the tooth so that stress concentrations in tooth tip and adapter are avoided.

Inclinations of the extra support surfaces made necessary for reasons of manufacturing techniques must obviously be accepted as long as the inclination is not excessive.

Claims

CLAIMS:

1. A wear part for a tool for an earth-working machine, of the type comprising a front tooth tip or cap (6, 33). which, in the fitted condition, protrudes beyond the front edge of the tool (2) in its working direction and which includes a female part (11, 34) facing rearwards in the working direction and cooperating with a corresponding, forwardly protruding male part (3, 29) of an adapter (2, 28), attached to the tool or forming an integral part of the front edge of the tool, and to which the tooth tip is releasably attached by a locking element (5), the male part (3, 29) of the adapter and the female part (11, 34) of the tooth tip providing support surfaces facing in different directions and adapted to contact each other, characterized in that the male part (3, 29) of the adapter provides at least two support surfaces (8 and 24; and 32 and 30, and 31) disposed each in its own plane at a distance from each other and adapted in use to face towards the surfaces of the earth being worked, and in that the female part (11, 34) of the tooth tip provides a cor responding number of oppositely facing support surfaces (12 and 24; and 35 and 38, and 39) adapted to contact the said support surfaces of said male part of the adapter.

2. A wear part as claimed in Claim 1, characterized in that the said support surface of surfaces (8) of the male part (3) which in use is (are) located closest to the surface of the earth is (are) provided by the bottom surface of the male part, and in that second said support surface (24) disposed in a plane laying above said bottom surface is provided by a nose (23) which protrudes forward of said bottom surface.

3. A wear part as claimed in Claim 1, characterized in that the said support surface or surfaces (32) of the male part (29) which in use is (are) located closest to the earth surface is (are) provided by the bottom surface of the male part, and in that the male part in addition, at a greater distance from the surface of the worked earth, provides two calluses (26, 27) substantially parallel with the said bottom surface, the lower surfaces (30, 31) of which facing towards the earth surface form a further two said support surfaces, one on either side of the male part.

4. A wear part as claimed in any of the preceding claims, characterized in that the contact between the said support surface or surfaces (8, 32) of the male part (3, 29) located closest to the surface of the worked earth and the corresponding support surface or surfaces, (12, 35) of the female part (11, 34) is substantially free of play, whereas a certain amount of play is provided between the other said support surfaces (24, 30, 31) of the male part (3, 29) and the corresponding support surfaces (25, 38, 39) of the female part (11, 34).

5. A wear part for a tool for an earth-working machine, substantially as hereinbefore described with reference to Figs. 1-3 or Figs. 4-6 of the accompanying drawing.