GB2136481A

GB2136481A - Cutter tool boxes and cutter assemblies

Info

Publication number: GB2136481A
Application number: GB08406893A
Authority: GB
Inventors: Robert George Knight
Original assignee: WILMET MINING Ltd
Current assignee: WILMET MINING Ltd
Priority date: 1983-03-18
Filing date: 1984-03-16
Publication date: 1984-09-19
Also published as: GB2136481B; GB8406893D0

Abstract

A road planer cutter drum (D) has a series of shoes (8) welded to is circumference for mounting tool boxes (2) by tongue and groove arrangements which have double tapers to provide wedging locations for the tool box both radially and circumferentially of the drum. Release means (14) are provided to allow a tool box to detach itself in the event of an overload, so avoiding uncontrolled damage to the drum and mounting means. The release means may be in the form of discreet elements or may be integral with the tool box itself. <IMAGE>

Description

SPECIFICATION Cutter tool boxes and cutter assemblies This invention relates to tool boxes or holders for cutting tools for such purposes as mineral cutting (e.g. mining) or civil engineering work.

It is concerned more particularly with tool boxes used with rotary assemblies such as the drum cutters of road planers-i.e. machines in which as the machine runs along a travel surface, the cutter drum rotates to remove the top of that surface or to put grooves in it.

These machines are used, for example, to remove the top surface of a road for renewal of that surface, or to remove mineral deposits in open-cast workings.

In such machines, a large number of shoes are welded to the drum, each shoe mounting a tool box to hold an individual cutting tool or pick releasably. The tools can then be changed very simply as they wear, but the boxes themselves suffer considerable wear in use and their removal and replacement is inconvenient and time-consuming.

According to one aspect of the present invention, there is provided a combination of a tool box and mounting means for use on a rotary cutter assembly, said tool box being provided with means for holding a cutting tool and with engagement means through which the box is releasably attached to the mounting means on the assembly, said engagement and mounting means comprising a cooperating dovetail tongue and slot having a radial taper arranged to hold the tongue in the slot against radially outward forces acting on the box, and having a taper in the circumferential direction of the assembly to restrain movement of the tool box counter to the direction of rotation, said dovetail tongue and slot providing a selflocking engagement for the tool box on the assembly.

According to another aspect of the invention, there is provided a tool box for a combination of tool box and mounting means as aforesaid, the tool box engagement means comprising said radial and circumferential tapers for co-operation with tapers on the mounting means.

One of the causes of wear and breakage in use is presented by obstacles in the path of the cutter, e.g. cast-metal manhole covers, and the impact of a tool on such an obstacle can severely damage the tool box as well as the tool. According to a further aspect of the present invention, a tool box provided with engagement means comprising radial and circumferential tapers for co-operation with mounting means on a rotary cutter assembly in a dovetail tongue and slot connection, has release means displaceable or frangible on application of an overload in the radial direction, thereupon to permit separation of the tool box from the mounting means.

In one form of this aspect of the invention the tongue and slot are so formed as to leave a space between the tongue and at least one of the opposed tapered faces of the slot, said space being provided for the reception of discrete release means or for the deformation or rupture of release means integral with tongue or slot of the tool box.

Thus, the tongue and slot may be so formed as to leave a space between adjacent side faces as viewed in the direction of cutting, such that the maximum width of the tongue at any position along its length is not greater than the entry width of the dovetail slot at the corresponding position along its length, and at least one make-up element e.g.

of a deformable or frangible material, is mounted between the adjacent side of said tongue and slot to retain the tongue firmly within the slot but to allow disengagement therebetween upon the application of a sufficiently large radially outward force to the tool box.

Alternatively, if an integral release means is provided, for example with the tool box having the tongue of the tongue and slot engagement, that tongue may comprise flanges or wings of a relatively narrow cross-section that in normal use provide a self-locking engagement between the tongue and the slot but that are free to deform when the load on the tool box becomes excessive, so allowing the tool box to tear itself free of its mounting.

In an alternative arrangement, the tongue is attached to the tool box by means that are deformable or frangible on application of the overload. Such means may be formed by tension bolts or shear pins, for example.

With these arrangements, the force transmitted to the tool box by an obstacle can be limited. Because the cutting tool projects outwards and forwards from the tool box, even if the force is imposed as a tangential impact on the tool tip, this will produce a moment on the tool box with a radially outwards force component, which of course acts on the release means, and if great enough the tool box is pushed free.

In a preferred form of the invention, the tool box comprises both the means of selflocking to the drum and the means of forceresponsive disengagement.

The invention will be described in more detail by way of example with reference to the accompanying schematic drawings, wherein: Figures 1-3 are side, front and underplan views respectively of a tool box according to the invention, in Fig. 2 its connection to a planer drum also being shown, Figures 4-6 illustrate modifications of the tool box and shoe in Figs. 1-3, and Figures 7-9 illustrate some further modified constructions in accordance with the invention.

The tool box shown in Figs. 1-3 comprises a body 2 with a bore 4 having a chamfer 6 on its forward end to receive a cutting tool (not shown), e.g. a point attack pick, projecting forwards and outwards from a cutter drum D. The drum will carry a large number of corresponding tool boxes spaced both circumferentially and axially over its peripheral surface.

Each tool box is mounted on the drum by means of a tongue and slot connection. On the periphery of the drum a series of shoes 8 are welded, each with a dovetail slot 10, and each tool box has on its radially inner face a tongue 1 2 with a complementary taper to that of a slot. The dovetail faces diverge radially inwardly but it is to be noted from the view of the body 2 in Fig. 3, that they also converge from front to rear.

The tongue 1 2 is significantly smaller than the slot 10, however. When the tool box is in its operative position, there is a substantially constant spacing between the opposed faces of the tongue and slot, and the maximum width of the tongue is less than the minimum width of the slot at corresponding stations along the length of the connection. The tool box is therefore held in place by packing or shims 1 4 inserted between the opposed faces of the tongue and slot, these shims being made of a readily deformable material, e.g. of plastics, or a material that is weak in shear.

In use the tool box is positioned in a shoe by sliding the tongue 1 2 into the slot 10 with the packings 1 4 interposed. For convenience of handling, there can be a single U-shaped packing with its limbs against opposite sides of the tongue. The taper angles of the tongue and slot are chosen sufficiently small such that the connection is self-locking and the tool box is thereby held in place by friction once the tongue is urged fully in the slot. If it is to be replaced, it can be equally easily released by driving it forwards from the slot.

If, while the planer is operating, the cutter pick mounted in a tool box strikes an obstacle, it will exert a turning moment on the tool box urging the box radially outwards and rearwards. If the force is sufficiently great, it will deform or fracture the packings, so freeing the tool box from its shoe, and the packings are designed for this to occur before the force is large enough to do any significant damage to the tool box or shoe. Of course, the tool box can afterwards be re-inserted with replacement packings as easily as at first.

Fig. 4 illustrates a modification of the tool box shown in Figs. 1-3 in that the tool box now has a dovetail slot 10a formed in it which will receive a complementary tongue (not shown) on the shoe fixed to the cutter drum. In this instance, of course, the dovetail faces diverge radially outwardly and also rearwardly.

Fig. 5 illustrates the use of a deformable packing or packings 1 4 on one side only of the tongue and groove engagement. Fig. 6 illustrates another double-sided packing arrangement in which a plurality of shims 24 on each side of the tongue-and-slot engagement have a substantially radially directed mating face 26 so allowing the shims held by the radially outer member of the assembly to slide outwards with that member when the radial load exceeds the frictional retaining force between the shims.

In Figs. 7 and 8 alternative constructions are shown in which a means of overload release is provided integrally by the tongues of the engagement, because of reliefs 32, 34, 36 respectively in the base (Fig. 8), or the sides (Fig. 7), and the root (Figs. 7 and 8) of the tongue cross-section, flanges or wings 38, 40, 42 are formed which still provide a firm engagement with the co-operating sides of the slot under normal load but which are more easily deformed by high loadings, so that the tongue is freed from the slot at a predetermined overload. It will be understood without further illustration that analogous configurations can be provided in the slotted member of the tongue-and-slot engagement to permit the lips of the slot to open on overload sufficiently to release the tongue.

Fig. 9 shows another form of release means in which the tongue 44 is a separate part and is attached to its member 46 by a weakened connection, shown here as a tension bolt 48, but other attachments, e.g. shear pins, brazing and adhesives can be used instead. When an overload is applied to the tool box, therefore, the member is separated from its tongue to avoid damage to the shoe.

If operating in conditions without obstructions, e.g. in open-cast mining, it may be unnecessary to provide an overload release means and the tool box may then arrange to be secured in its shoe by a dovetail engagement as described, but without the use of packing and shims as shown in Figs. 1-3.

Alternatively, there may be specific circumstances in which an overload release means as disclosed herein is required but it is not necessary to provide a dovetail engagement between the tool box and its mounting means or it is possible to provide a dovetail engagement that tapers in only one direction, radial or circumferential.

Claims

1. A combination of a tool box and mounting means for attaching the tool box to a rotary cutting assembly, said tool box being provided with means for holding a cutting tool and with engagement means through which the box is releasably attached to the mounting means, said engagement and mounting means comprising a co-operating dovetail ton gue and slot having a radial taper arranged to hold the tongue in the slot against radially outward forces acting on the box, and having a taper in the circumferential direction of the assembly to restrain movement of the tool box counter to the direction of rotation of the drum, said dovetail tongue and slot providing a self-locking engagement between the tool box and the drum.

2. A tool box and mounting means according to claim 2 wherein release means are provided that are displaceable or frangible on application of an overload in said radial direction, thereupon to permit separation of the tool box from the mounting means.

3. A tool box and mounting means according to claim 1 wherein the tongue and slot are so formed as to leave a space between the tongue and at least one of the opposed tapered faces of the slot, said space providing for the reception of discrete release means or for the deformation or rupture of release means integral with the tongue or slot of the tool box.

4. A tool box and mounting means according to claim 3 wherein said space is provided between adjacent side faces of the tongue and slot such that the maximum width of the tongue at any position along its length is not greater than the entry width of the dovetail slot at the corresponding position along its length, at least one make-up element being mounted between the adjacent sides of said tongue and slot to retain the tongue firmly within the slot but to allow dis-engagement therebetween upon the application of a sufficiently large radially outward force to the tool box.

5. A tool box and mounting means according to claim 4 wherein said at least one element is arranged to deform or rupture to release the tool box.

6. A toolbox and mounting means according to claim 4 wherein said at least one element is arranged to provide a frictional engagement that is released in overload conditions.

7. A tool box and mounting means according to claim 6 wherein at least two said elements are provided having abutting faces that lie in a radially directed plane extending through the opening of the dovetail slot.

8. A tool box and mounting means according to any one of claims 4 to 7 wherein said at least one element comprises a Ushaped packing that extends around opposite side faces of the tongue.

9. A tool box and mounting means according to claim 2 wherein that one of said tongue and said slot provided on the tool box comprises at least one integral element that is arranged to deform or rupture to release the tool box when subject to overload forces.

10. A tool box and mounting means according to claim 9 wherein that one of said tongue and said slot provided on the tool box comprises flanges or wings of a relatively narrow cross-section that produce a self-locking engagement between the tongue and the slot but that are deformable when the load on the tool box becomes excessive, so releasing the tool box from the mounting means.

11. A tool box and mounting means according to claim 2 wherein the tongue is attached to the tool box by means that are deformable of frangible on application of overload forces.

1 2. A tool box for a combination of tool box and mounting means according to any one of the preceding claims.

1 3. A tool box and mounting means for use in a rotary cutter assembly, constructed and arranged substantially as described herein with reference to any of the examples illustrated in the accompanying drawings.

1 4. A rotary cutter assembly provided with a series of tool boxes and mounting means according to any of of claims 1 to 11 or claim 1 3.

1 5. A rotary cutter assembly having a tongue or a slot for attachment to a cooperating slot or tongue of tool box mounting means on the planing drum, said tool box tongue or slot being arranged to provide wedging location for the tool box both radially and circumferentially of the drum, and at least one release element integral with or discrete from the tool box being arranged to be displaceable or frangable on application of an overload force to the tool box in the radial direction, thereby to permit separation of the tool box from its mounting means.