WO1999041457A1

WO1999041457A1 - Dual action cutting device

Info

Publication number: WO1999041457A1
Application number: PCT/GB1999/000474
Authority: WO
Inventors: John Williamson
Original assignee: Errut Products Limited
Priority date: 1998-02-13
Filing date: 1999-02-15
Publication date: 1999-08-19
Also published as: GB9803003D0

Abstract

A drum for use in a cutting device having at least two inter-connected drum cage sections (20, 22) adapted to be mounted on a common drive shaft (23), each cage section comprising support flanges (24) for the end portions of a plurality of peripherally spaced cutter receiving shafts (30), the cutter receiving shafts (30) at one cage section (20) adapted to be angularly displaced from those of the adjacent cage section (22).

Description

DUAL ACTION CUTTING DEVICE

This invention relates to a dual action cutting device and is particularly concerned with cutting devices intended to remove surface material from hard surfaces such as concrete, asphalt and a wide range of floorings. Such devices are often referred to as planers. They can be used for a variety of purposes such as for roughening or deep grooving the surface of a concrete floor to prevent slippage or for de-scaling paint and rust from surfaces such as steel.

Devices for such purposes are required to be very robust in construction. Presently available planers are manually operated devices, which are driven by the operator over the surface to be abraded. Adjacent the surface they have a rotating drum of cage form which supports a number of peripherally spaced shafts which support suitable cutting tools in manner to provide radial and rotational movement, with respect to the axis of the shaft on which they are marked and which project beyond the periphery of the drum and score and abrade the surface by flailing against the surface during rotation of the drum. The cutters themselves can vary in cutting width and in diameter dependent on the desired abrading effect. It will be appreciated that all parts of such planers are subject to considerable stress. The cutters themselves are conventionally tungsten tipped or of hardened steel, while the cutters are mounted on shafts of hardened steel which need to be supported across the width of the planer to avoid premature failure. In addition, the drum itself is required to be of hardened steel because of the considerable stress generated. 2

The use of hardened steel for both shafts and drums is expensive and, during heat treatment before use, deformation often occurs thus giving rise to significant wastage. In use, the effects of high impact cause wear, especially in the region of the mounting of the shafts in the drum. Such wear causes elongation of the bores in the drum and unwanted ingress of dust and debris, thus shortening the life of the drum.

There have been attempts to overcome these problems. Thus, sacrificial hardened bushes have been used in high wear areas: this can be satisfactory at the ends of the drum but is not satisfactory for locations where the shafts need to pass through intermediate drum flange supports. No satisfactory method of fitting bushes to these central supports has been found. Even screwed in and heat shrunk bushes have quickly become loose and moved out of the flanged support, thus exposing the support to damage. An alternative design has proposed the use of differing axial positioning of cutters on each shaft thus reducing the total number of cutters and attempting to spread the impact stress. However this does not remove the requirement for intermediate support for the cutter support shafts and the need to use expensive materials to cope with the resultant wear.

The present invention seeks to overcome these problems.

According to the present invention, there is provided a drum intended for use in a cutting device having at least two interconnected drum cage sections adapted to be mounted on a common drive shaft, each cage section comprising support flanges for the end portions of a plurality of peripherally spaced cutter-receiving shafts, the cutter-receiving shafts of one cage section adapted to be angularly displaced from those of the adjacent cage section. Reference herein to cutting is to the action of saws, drills, crushers, milling machines, polishers and the like which removes material to give an altered surface.

It is a particular advantage that the drum according to the invention provides higher impact frequency for lower reaction force impact, whereby efficiency is maintained with smoother operation. Moreover, the drum provides intermediate support, with reduced wear, of shafts.

The drum cages are preferably mounted coaxially on a common drive shaft. The drive shaft may be integral with or received in suitable mountings on at least one support flange of each cage section, or may be received in an axial sheath extending through the drum and integral with or, supported on mountings associated with the respective flanges. The drive shaft may be adapted to be received at one end in a bearing, to allow free rotation, and at the other end in a drive pulley or other drive mechanism. It is an advantage that the drums according to present invention have been found to resist wear and do not therefore need to be replaced. Preferably therefore drums according to the invention comprise a solid drive shaft which is integral with or mounted directly on the respective flanges.

The cutter receiving shafts are suitably adapted to provide a dual cutting action, by virtue of relative rotational and radial movement of cutters with respect to the receiving shaft as a result of centrifugal action and impact force. Cutters are suitably in the form of annular discs comprising a profiled outer rim in the form of pointed, jagged tooth, square ended or the like radial projections, each projection serving as a cutting blade. Cutters are adapted to be received on the shaft via their central apertures. Preferably the central aperture is of larger diameter than the shaft external diameter, thereby allowing relative movement thereof. For example the cutter blade may have a central aperture of the order of 15-16mm, and the shaft may have an external diameter of 10- 12mm.

A plurality of the cutter annuli may be received on the shaft adjacent each other, or distanced apart by spacers, depending on the intended use. For example needle (pointed) cutters may be mounted on a shaft with substantially no spacing therebetween, for roughening of a domestic or commercial surface. Alternatively cutters may be mounted with spaces of for example 1 inch width therebetween for texturing surfaces prone to accumulation of dirt, such as agricultural surfaces including farmyards, whereby surfaces are provided with continuous grooves with spacing of 1 inch there between.

Suitably the at least two drum cage sections are interconnected in manner to provide a continuous cutting surface if desired. Interconnected drum cage sections may comprise a common neighbouring support flange or may comprise individual dedicated neighbouring support flanges. It is a particular advantage of the process of the present invention that, by virtue of the angular displacement of the cutter receiving shafts of adjacent caged sections, neighbouring support flanges, i.e. for interconnected ends of two respective drum cage sections, may be overlocked, whereby the neighbouring support flange of each cage section is located within the neighbouring cage section, or a common support flange of neighbouring drum cage sections may comprise support locations for cutter receiving 5 shaft of one cage section, axially displaced with respect to, and overlooking, support locations for cutter receiving shafts of the neighbouring cage section. By this means there is overlap of cutter receiving shafts of neighbouring interconnected drum cage sections, and corresponding continuity or overlap of cutters.

In a preferred construction the cage sections have neighbouring support flanges which comprise peripherally disposed lobes each providing a mounting for one end of a cutter receiving shaft, the shafts of one cage section passing through the spacing between the lobes of the neighbouring support flange.

The neighbouring support flanges may be separated by spacer or other suitable means mounted on the drive shaft.

A drum cage as herein before defined may be any of suitable cross sectional shape as determined by the shape of support flanges and/or the number of cutter receiving shafts. Preferably a drum cage comprises a hollow cage of polygonal or continuous shape, for example a cage comprising 3,4,5,or 6, cutter receiving shafts, may be of triangular, square, heptagonal or hexagonal cross section, or of circular cross section.

It will be appreciated therefore that a drum comprises a total number of cutter receiving shafts equal to the sum of the shafts of the individual drum cage sections. 6

Interconnected drum cage sections may have the same or a different number of cutter receiving shafts, and preferably have the same number of cutter receiving shafts.

The cutter receiving shafts of each cage section may be symmetrically or non-symmetrically spaced, and are preferably symmetrically spaced. Cutter receiving shafts of one cage section may alternate regularly with cutter receiving shafts of an interconnected caged section; or a plurality of cutter receiving shafts of one cage section may alternate with individually or with a plurality of receiving shafts of an adjacent cage section. Preferably cutter receiving shafts of each cage section alternate one on one that is, individually.

Cutter receiving shafts of respective cage sections may be angularly displaced, for example by mounting with angular displacement on the common drive shaft, or may be adapted to be angularly displaced on impact, for example by linear mounting, but with a predetermined rotation of one or both cage sections with respect to the drive shaft. Preferably shafts are mounted with angular displacement.

Cutter receiving shafts of one cage section may be angularly displaced symmetrically or asymmetrically between cutter receiving shafts of the neighbouring drum cage section.

Preferably, the angular displacement is approximately half the peripheral spacing between the cutter-receiving shafts of a single cage section thereby evening-out the cutter impact pattern as the device rotates. According to an especially preferred form of the invention, the ends of the cutter-receiving shafts are mounted in bushings held by the support flanges and replaceable when worn. The bushings are preferably of top hat form so as to present a blind end to the ends of the cutter-receiving shafts.

It will be appreciated that a drum as herein before defined comprising angularly displaced cutter receiving shafts as herein before defined, and additionally comprising one or more continuous cutter receiving shafts, being common to the drum cage sections, is considered to lie within the scope of the present invention, and benefit from the advantages of reduced wear and reduced vibration effect, although such a drum is not preferred.

The invention further comprises surface abrading devices comprising at least one drum as defined above and surface abrading devices wherein the cutter receiving shafts of the or each drum carry a plurality of cutters.

The invention further comprises a method for cutting, preferably for surface abrasion comprising passing a cutting device comprising at least one drum as defined above across the surface to be altered, with simultaneous rotation thereof in the direction or counter direction of travel, whereby rotation of cutter receiving shafts of one cage section is temporally displaced with respect to rotation of cutter receiving shafts of the adjacent cage section.

The invention further comprises the use of at least one drum as defined above in a method for cutting as defined above in low impact manner, to remove surface material, to roughen or deep groove the surface and the like. The invention further comprises a bush, cutter or cutter receiving shaft as defined above for use in a drum as defined above. Advantageously a bush or a cutter may be made of hardened material, such as hardened steel, and a cutter receiving shaft maybe of non-hardened material such as mild steel.

The invention will now be described by way of example with reference to the accompanying drawings wherein:

Fig 1 is a perspective view of a surface-abrading device:

Fig 2 is a perspective view of a known drum for use with the device of Fig 1 :

Fig 3 a, b and c illustrates three types of cutter suitable for use with the device of Fig 1 :

Fig 4 is a perspective view of a drum in accordance with the invention:

Fig 5 is longitudinal section through the drum of Fig 4 with a plurality of cutters in place:

Fig 6 is a perspective view of an alternative drum in accordance with the invention:

Fig 7 is an end view of the drum of Fig 6:

Fig 8 is a longitudinal section through the drum of Fig 6. Figs 9 and 10 are a longitudinal section and end view of a further alternative drum in accordance with the invention;

Figs 11 , 12, and 13 are a perspective view, an end view and a longitudinal section of a still further alternative drum in accordance with the invention; and

Figs 14 and 15 are an end view and a longitudinal section of a still further alternative drum in accordance with the invention.

Fig 1 shows a surface abrading device of known construction. The device is generally of upright construction with operating handles 2, motor unit 4 operated via wheel 6 and a base housing 8 intended to house one or more drum cages of the type shown in Fig 2. The known drum cage 10 of Fig 2 comprises a central drive shaft 11 extending through end support flanges 12 and through intermediate support flange 13.

The support flanges 12 and 13 support a plurality of peripherally disposed cutter receiving shafts 14 on each of which can be mounted a plurality of cutters of a wide variety of design depending on the abrading action to be carried out and the nature of the surface to be abraded. Representative cutters are shown in Fig 3 a, b and c. Such cutters are suitably tungsten tipped or of hardened steel. Drums such as that shown in Fig 2 suffer from the problems of expense, wear and limited life as described above.

Figs 4 and 5 show one form of drum in accordance with the invention. The drum comprises two drum cage sections 20 and 22 through which passes a common drive shaft 23 which, in use, is mounted within the base housing 8 10 of a device such as that shown in Fig 1. Each cage section 20 and 22 comprises an outer annular support flange 24 and an inner support flange 25. Inner support flanges 25 each have a central land 26, through which the drive shaft 23 passes, surrounded by three peripherally disposed lobes 27. The inner support flanges are linked together via central spacer 29. The inner support flange of cage section 20 is axially closer than the inner support flange of cage section 22 to the outer support flange of cage section 22. Conversely, the inner support flange of cage section 22 is axially closer than the inner support flange of cage section 20 to the outer support flange of cage section 20. This disposition is clearly shown in Fig 4. This enables cutter-receiving shafts 30 to extend from the outer support flange 24 of each cage section through the spacings between the lobes 27 to the inner support flange 25 of that cage section. Each cage section 20 and 22 has three cutter receiving shafts 30, the shafts of cage section 20 being angularly displaced from those of cage section 22 by an amount equal to half the peripheral spacing between the cutter-receiving shafts. A plurality of suitable cutters is mounted on each cutter-receiving shaft as shown in Fig 5.

The ends of each shaft 30 are mounted in bushings 32 fitted within suitable blind apertures in the outer and inner support flanges 24 and 25. The bushings are suitably of top hat construction.

It will be appreciated that the construction as shown in Figs 4 and 5 offers several advantages. Thus each cutter-receiving shaft 30 is of comparatively short length and is mounted securely at each end in a support flange 24 or 25. The bushings 32 can be replaced when worn, thus preventing build up of wear problems in the drum cage and ingress of debris. The drum cages can therefore be constructed from conventional steel without the need for 1 1 expensive and wasteful steel hardening. In addition, because the cutter- receiving shafts are short, there is less danger of distortion during the heat treatment of the shafts prior to use.

The drum cage shown in Figs 4 and 5 shows each cage section having 3 cutter receiving shafts. It will be appreciated that each cage section can have more or less shafts dependent on the abrading task to be performed. Typically, drums have 3, 4 or 6 sets of shafts each fitted with cutters. As each set of cutters impacts the ground once during each drum revolution there is considerable impact. The construction in accordance with the invention doubles the number of impacts per drum revolution, while each impact has half the reaction force. The reverse force on the machine - and hence the operator - is thus reduced and the operation is smoother. Further, since the impact frequency is higher, the potential deleterious effects of vibration are significantly reduced. Thus for example, it has been shown that increasing the hand transmitted vibration frequency from 100 Hz to 200 Hz can give a 50% reduction in operator hand injury.

Figs 6 to 8 show an alternative design of drum in accordance with the invention. In this design, the end support flanges 35 are of square section with chamfered corners 36, while the intermediate support flanges 37 each have four lugs 38. Support flanges 35 and lugs 38 of the intermediate flanges 37 thus support four cutter-receiving shafts (not shown) for each drum cage section. The resulting disposition of the shafts is best seen in the end view of Fig 7.A square drive shaft 39 passes through the support flanges for driving the drum cages and the cutters mounted (in use) on the cutter- receiving shafts. The intermediate flanges 37 are linked via a spacer 40 through which the shaft 39 also passes. As for Figs 4 and 5, the ends of the 12 cutter-receiving shafts are preferably mounted in the support flanges by means of bushings, which can be replaced when worn.

Figs 9 and 10 show a further alternative design of drum having end support flanges 41 and intermediate support flanges 42 each having four lugs to support, with flanges 41, cutter-receiving shafts (not shown). Flanges 42 are spaced by spacer 43. Flanges 41 and 42 are mounted on centre tube 44, the ends of which provide socket 45 to receive the drive mechanism.

Figs 11 to 13 show an alternative design of drum having three lugs on each intermediate support flange, while Figs 14 and 15 show a still further alternative design with cutters mounted on the cutter receiving shafts.

Claims

13CLAIMS

A drum for use in a cutting device having at least two inter-connected drum cage sections adapted to be mounted on a common drive shaft, each cage section comprising support flanges for the end portions of a plurality of peripherally spaced cutter receiving shafts, the cutter receiving shafts at one cage section adapted to be angularly displaced from those of the adjacent cage section.

A drum as defined in Claim 1 wherein the drum cages are mounted co- axially on a common drive shaft.

3. A drum as defined in Claim 1 comprising a solid drive shaft which is integral with or mounted directly on the respective flanges.

4. A drum as defined in any of Claims 1, 2 or 3 wherein the cutter receiving shafts are suitably adapted to provide a dual cutting action preferably by virtue of relative rotation and radial movement of cutters with respect to the receiving shaft as a result of centrifugal action and impact force.

5. A drum as defined in any of Claims 1-4 comprising cutters in the form of angular discs comprising a profiled outer rim in the form of pointed, jagged tooth, square ended or the like radial projections, each projection serving as a cutting blade.

6. A drum as defined in any of Claims 1-5 wherein the cutters are adapted to be received on the shaft via their central apertures. 14

7. A drum as defined in Claim 6 wherein the central aperture of each cutter is of larger diameter than the shaft external diameter, thereby allowing relative movement thereof.

8. A drum as defined in Claim 7 wherein the cutter blade has a central aperture diameter of the order of 15-16 mm and the shaft has an external diameter of 10-12 mm.

9. A drum as defined in any of Claims 1-8 wherein a plurality of the cutter's annuli are received on the shaft adjacent each other with substantially no spacing therebetween.

10. A drum as defined in any of Claims 1-8 wherein plurality of the cutter annuli are received on the shaft distanced apart by spacers, for provision of continuous spaced grooves.

11. A drum as defined in any of Claims 1-10 wherein the at least two drum cage sections are inter-connected in manner to provide a continuous cutting surface.

12. A drum as defined in Claim 11 wherein an overlap of cutter receiving shaft of neighbouring inter-connected drum cage sections and corresponding continuity or overlap of cutters is provided.

13. A drum as defined in Claim 12 wherein the drum cage sections comprise individual dedicated neighbouring support flanges which are over-locked, whereby the neighbouring support flange of each cage section is located within the neighbouring cage section. 15

14. A drum as defined in Claim 12 wherein inter-connected drum cage sections comprise a common neighbouring support flange comprising support locations for cutter receiving shaft of one cage section, axially displaced with respect to and over-locking, support locations for cutter receiving shafts of the neighbouring cage sections.

15. A drum as defined in Claim 13 comprising neighbouring support flanges which comprise peripherally disposed lobes, each providing a mounting for one end of a cutter receiving shaft, the shaft of one cage section passing through the spacing between the lobes of the neighbouring support flange.

16. A drum as defined in any of Claims 1-15 wherein the drum cage comprises a hollow cage of polygonal or continuous shape.

17. A drum as defined in any of Claims 1-16 wherein inter-connected drum cage sections have the same number of cutter receiving shafts, which are preferably symmetrically spaced.

18. A drum as defined in any of Claims 1-17 wherein cutter receiving shafts of each cage section alternate individually with cutter receiving shafts of an adjacent cage section.

19. A drum as defined in any of Claims 1-18 wherein cutter receiving shafts are mounted with angular displacement on the common drive shaft. 16

20. A drum as defined in Claim 19 wherein the angular displacement is approximately half the peripheral spacing between the cutter receiving shafts.

21. A drum as defined in any of Claims 1-20 wherein the ends of the cutter receiving shaft are mounted in bushings held by the support flanges and are preferably replaceable when worn.

22. A drum as defined in Claim 21 wherein the bushings are of top hat form.

23. A surface abrading device comprising at least one drum as defined in any of Claims 1-22 wherein the cutter receiving shafts of the or each drum preferably carry a plurality of cutters.

24. A method for cutting comprising passing a cutting device comprising at least one drum as defined in any of Claims 1-22 across the surface to be altered, with simultaneous rotation thereof in the direction or counter direction of travel, whereby rotation of cutter receiving shaft of one cage section is temporally displaced with respect to rotation to cutter receiving shaft of the adjacent cage section.

25. The use of at least one drum as defined in any of Claims 1-22 in a method for cutting, preferably for surface abrasion as defined in Claim 24 in low impact manner, to remove surface material, roughen or deep groove the surface.

26. A bush, cutter, or cutter receiving shaft as defined in any of Claims 1- 22 for use in a drum as defined in any of Claims 1-22. 17

27. A drum substantially as described in the description or shown in the figures.