GB2043025A

GB2043025A - Cutter tooth assembly

Info

Publication number: GB2043025A
Application number: GB7907741A
Authority: GB
Original assignee: Bofors AB
Current assignee: Saab Bofors AB
Priority date: 1979-03-05
Filing date: 1979-03-05
Publication date: 1980-10-01
Also published as: GB2043025B

Abstract

A cutter tooth assembly for earth moving machines, the assembly having an adapter 1 which can be fixed to a tool V of an earth moving machine in a predetermined position which will align the tooth 2 at a predetermined working angle when the tooth is inserted in the adapter. The adapter has a claw 9 to engage an edge 6 of the tool, a bolt 4 coupling the adapter to a bracket 3 mounted on the tool pulls the claw into tight engagement with the tool, preferably the tool and adapter have complementary shaped surfaces to ensure that the tooth is held in a predetermined position in the adapter and a locking wedge 5 is provided to prevent the tooth being withdrawn from the adapter. <IMAGE>

Description

SPECIFICATION Cutter tooth assembly The present invention relates to a cutter tooth assembly for earth-moving machines used for breaking up and disintegrating particularly hard soil, unconsolidated rock and coral.

The tooth assembly to be described herein has been designed to allow every tooth to be attached to a tool in the most effective position for efficient use of the tool.

The cutter tooth assembly according to this invention is primarily intended for use in rotating dredge cutters for rock dredging, but is also suitable for use in bucket wheel dredgers for working unconsolidated rock.

One particular type of dredge cutter comprises a plurality of toothed spiral-helical wings fastened to a central hub and extending rearwardly and outwardly from the hub towards a connecting rear supporting ring in the tool feed direction. The tool rotates around the hub and, on a level with the supporting ring, is connected to a suction nozzle through which the soil broken- up by the tool is removed. A typical cutter of this kind is described in the U. S. Patent No. 3,808,716. The detailed design of the cutter is not critical and will therefore not be dealt with further.

A cutter tooth assembly according to this invention comprises an adapter, removably fastened to the tool, and to this adapter a removably fastened tooth and means for fastening both the adapter and tooth in their respective places. A characteristic feature of this cutter tooth assernbly is that the adapter has a claw which grips the front edge of the tool and is held in place by a force which is applied between the adapter and a bracket fixed to the tool and arranged in line behind the adapter. According to a preferred embodiment, the force is applied by a bolt running through the bracket and the adapter.

So that the position of the adapter and hence the position of the tooth shall not be directly dependant on the form of the front edge of the tool, the cutter tooth assembly has a fitting block whose rear edge is welded to the front edge of the tool. The fitting block thus constitutes a direct extension of the front edge of the tool but at the same time allows adjustments of the fitting block relative to the working direction of the tool so that the adapter, when installed, gives the tooth the correct cutting angle. This is especially important for dredge cutters, the spiral-helical wings of which are difficult to manufacture with sufficient precision so that the fitting block allows the tooth to be positioned to give the best possible cutting angle.The rotating dredge cutter is moreover one of the earth-moving tools for which there are the most stringent requirements as to the way in which the teeth are angled.

The fitting block should preferably be installed at the front edge of the tool with the aid of a removable jig which is used both to set the fitting block and the socket and hold them in place while they are being welded in their correct positions.

As tooth geometry is very important for dredge cutters it may be necessary to turn the fitting blocks and to set them obliquely in relation to the front edge of the wing where there is local unevenness in the cutter wing.

Even correctly positioned teeth are affected by lateral forces. The fitting blocks are therefore shaped to prevent displacement of the adapter along the front edge of the fitting block. This can be achieved by making the front edge of the fitting block convex with a radius which differs from the distance between the claw on the adapter and the bracket. In principle, this gives two possibilities firstly that the front edge of the fitting block has a substantially smaller radius and that the claw has two contact points against the fitting block, the contact points being located one on each side of the centre plane of the adapter, and secondly that the front edge of the fitting block has a substantially larger radius.

It is also possible to lock the adapter to the block by making a notch in the front edge of the fitting block to receive complementary shaped surfaces on the adapter. Lateral forces exerted on the front part of the adapter are then taken up by the side surfaces of the notch. The fitting block may be provided with a convex rear edge to mate with a concave recess in the front edge of the tool.

This configuration makes it is possible to weld the fitting block in the tool with the above mentioned notch mating with the complementary surfaces of the claw of the adapter aligning it at a predetermined angle to the front edge of the tool.

Lateral forces applied on a level with the front edge of the adapter can also be resisted by guide lugs extending upwards from the fitting block or the front edge of the tool into a recess or groove in the adapter. It is, of course, also possible to mount a guide lug on each side of the adapter.

Lateral forces on a level with the rear end of the adapter can be absorbed by one or a plurality of guide lugs fastened to the tool or the bracket.

A preferred embodiment of a cutter tooth assembly in accordance with this invention will now be described in more detail with reference to the accompanying drawings in which: Figure 1 shows a partly side sectioned cutter tooth assembly according to this invention; Figures 2 and 3 show in plan view alternative forms of cutter tooth assemblies; Figure 4 is an enlarged part of Figure 1 showing how the teeth are fastened; Figure 4a shows the locking member used to lock a tooth in the adapter of the tooth assembly; Figures 5 and 6 show a cutter tooth assembly with another type of fitting block in side and plan elevations respectively; and Figures 7 and 8 show the adapter and fitting block of Figures 5 and 6.

A cutter tooth assembly according to this invention is shown in Figs 1 to 4 and comprises an adapter 1 to which is locked a removable tooth 2.

A bracket 3 is fixed to a tool V (in this case the wing of a dredge cutter) to enable a bolt 4 of the assembly to run through the bracket and adapter to join the two components. A locking member 5 locks the tooth 2 in the adapter 1 and a fitting block 6 is welded to the front edge of the tool. A guide lug 7 is fastened to the tool and/or guide lugs 8a and 8b.

The adapter may be made in two halves with the parting line extending vertically. The halves may be welded together along the parting line.

The adapter 1 has a claw 9 which grips the front edge of the fitting block 6 which is welded to the front edge of the tool. The bolt 4 passes through a hole 10 in the adapter 1 and extends through an opening 11 in the bracket 3 where a nut is threaded on the end of the bolt with a washer 1 2 between the nut 13 and the bight of the bracket 3.

Welded on to the face of the bracket 3 facing the adapter is a guide bushing 14 which can absorb lateral forces.

The guide lug 7 welded to the tool and engaging in an opening or groove in the adapter and the alternative guide lugs 8a and 8b are also able to absorb lateral forces.

The bracket may also be provided with a guide lug which engages a groove in the adapter.

Figures 2 and 3 show two alternative forms of fitting block 6. In Figure 2, the convex front edge of the fitting block has a substantially smaller radius than the distance between the front edge of the claw 9 and the position in the bight of the bracket 3 where the bolt 4 enters. By providing on each side of the claw 9 contact points 1 5 and 1 6 which bear against the convex edges the fitting block, the adapter is held against arcuate movement about the block.

'In Figure 3, the radius in question is greater than the distance between the claw and the bracket, and also in this way, the adapter is held against arcuate movement about the block. Also the guide lugs 8a and 8b can be used to prevent lateral movement of the adapter.

The fastening means for the tooth shown in Figures 1 and 4 comprises complementary shaped lands and grooves 1 7, 18 (Figure 4) formed in the tooth and the adapter. The tooth 2 is inserted in the adapter in the direction shown by the arrow T.

The lands and the grooves and the edges 1 9 and 20 (Figure 1) mate with each other and determine the position of the tooth relative to the adapter and thereby the tool. The tooth 2 is prevented from being pulled out of the adapter by a locking wedge 5 comprising two oppositely facing metal parts, 22 and 23, with a middle part 24 there between, the part 24 being made of resilient material.

The locking wedge is placed in a groove 21 between two portions 25 and 26 depending from the bottom of the tooth, and inserted with the tooth into the adapter.

A feature of the locking wedge 5 is that part 23 has an intermediate portion of reduced thickness forming two oppositely directed shoulders 27 and 28 which allow the intermediate portion to buckle and distort into the shape showing figure 4 when a blow is directed against the end of the wedge 5 nearest the shoulder 28.

Figure 4a shows the locking member in the condition before it is buckled. On buckling the wedge 5, the intermediate portion is forced into contact with a rounded edge 29 of one wall of a trough 30 in the adapter. Thus the tooth 2 is prevented from being withdrawn from the adapter 1 by the forward return bent portion of the upper part 22 of the wedge 5 bearing against the depending portion 25 and the intermediate portion 6f the wedge 5 bearing against the rounded edge 29 of the trough 30.

To remove the tooth from the adapter, a drift is placed into an opening 31 in the upper portion of the claw 9 and forced inwards by a blow on that end protruding from the opening 31. This buckles the intermediate portion of the wedge 5 back into the shape shown in Figure 4a so that the intermediate portion clears the edge 29 of the wall of the trough 30 and allows the tooth to be withdrawn.

Other securing members can be used to lock the tooth in its position in the adapter. There are, for instance, some different types of known locking wedges which can be inserted through transverse openings, such as opening 31.

Also other directions of installation of the tooth are conceivable.

When installing a cutter tooth the position of the tooth is first determined in relation to the tool and the fitting block and the bracket are thereafter held in position with the aid of a jig so that they can be welded in position on the tool.

With the bracket and fitting block welded in position, all that remains to be done is to fasten the adapter with its draw bolt 4 and to insert the tooth.

The cutter tooth assembly shown in Figures 5 to 8 is held in a predetermined position relative ta the tool by a fitting block which is different to those shown in Figures 2 and 3.

Some of the components are exactly the same as those shown in Figures 1 to 4a and are given the same reference numerals.

A fitting block 32 has an arcuate rear surface 33. A corresponding recess is cut in the front edge of the tool V providing a complementary shape for the rear surface 33 of the fitting block 32. The fitting block is secured in a predetermined position in the recess in the front edge of the tool by the aid of a jig and is then carefully welded in the predetermined position.

The fitting block has two lands 34 and 35 and a centrai groove 36.

The same configuration of parts used to fasten the tooth 2 in the adapter 1 as shown in Figures 1 to 4 is also used in the adapter 37 shown in Figs. 5 to 8. The adapter 37 has grooves 38 and 39 which fit the lands 34 and 35 in the fitting block 32.

The adapter is thus provided with two claws gripping the fitting block. The assembly shown on Figs. 5 to 8 is easy to manufacture both by forging and by casting and it is also extremely strong A bracket 40 guide corresponding to the bracket 3 in Figure 1 is provided with a guide lug 41. The adapter is secured on the fitting block by the bolt 4 as in the first embodiment described with reference to Figures 1 to 4a.

Claims

1. A cutter tooth assembly for tools for earthmoving machines comprising an adapter removably fastened to the front edge of the tool, and a tooth removaby locked to the adapter, wherein the adapter has a claw which engages the front edge of the tool and is pulled onto side edge by a force which is applied between the adapter and means fixed to the tool.

2. A cutter tooth assembly according to claim 1, wherein said means comprises a bracket and said force is applied by a bolt coupling the adapter to the bracket.

3. A cutter tooth assembly according to Claim 1 or claim 2, including a fitting block with an arcuate front edge which has its rear edge welded to the front edge of the tool so that the front edge of the fitting block constitutes a direct extension of the front edge of the tool at a place where the adapter is to be installed.

4. A cutter tooth assembly according to Claim 3, when appendant to Claim 2, wherein that part of the front edge of the fitting block which the claw of the adapter engages has an arcuate shape and the radius of the arc differs from the distance between the front edge of the fitting block and the bracket.

5. A cutter tooth assembly according to Claim 4, wherein the part of the arcuate front edge of the fitting block which the claw of the adapter engages has a radius which is less than the distance between the front edge of the fitting block and the bracket and the claw of the adapter has two contact points against the front edge of the fitting block located at a distance from each other.

6. A cutter tooth assembly according to Claim 4, wherein that part of the front edge of the arcuate fitting block which the claw of the adapter engages has a radius which is greater than the distance between the front edge of the fitting block and the bracket.

7. A cutter tooth assembly according to any one of Claims 1 to 6, wherein said fitting block has an arcuate rear surface which fits into a corresponding recess in the front edge of the tool.

8. A cutter tooth assembly according to Claim 7, wherein said fitting block includes a guide slot for the claw of the adapter.

9. A cutter tooth assembly according to any one of the foregoing claims, wherein the adapter coacts with one or a plurality of guide lugs fixed to the tool to absorb lateral forces acting upon the adapter.

1 0. A cutter tooth assembly according to any one of Claims 1 to 7, wherein the tooth and the adapter have complementary shaped lands and grooves which when the tooth is installed in its place together determine the position of the tooth in the adapter in all directions except the one from which the installation of the tooth takes place, the assembly including a locking member which can be inserted from the same direction as the tooth in a groove between the tooth and the adapter, the locking member comprising two oppositely facing parts joined together by a resiiient middle part, at least one of the oppositely facing parts being provided with a portion of reduced strength which can be deformed to lock the tool in the adapter.

11. A cutter tooth assembly according to Claim 10, wherein the adapter is provided with a through opening and a trough into which said portion of said locking member deforms, the opening being positioned so that a drift inserted through the opening forces the intermediate portion of the locking member out of the trough in the adapter.

12. A cutter tooth assembly according to any one of claims 1 to 8, wherein the tooth and the adapter have complementary shaped lugs and grooves which when the tooth is installed in place together determine the position of the tooth in the adapter in all directions except the one from which the installation takes place, and in which direction the position of the tooth is determined by a locking wedge which is inserted through an opening which extends through the adapter across the direction in which the change of tooth takes place, the locking wedge thus inserted being in contact with cleats on the tooth and the edges of the opening.

13. A cutter tooth assembly according to any one of claims 1 to 12, wherein the adapter is made in two halves, the parting line of which extends along the adapter, the halves being welded together along said parting line.