GB2373746A

GB2373746A - Cutting machine

Info

Publication number: GB2373746A
Application number: GB0103650A
Authority: GB
Inventors: Robert Henry Williams
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-02-14
Filing date: 2001-02-14
Publication date: 2002-10-02
Also published as: GB0103650D0

Abstract

A cutting machine comprises cutting means 46, which may be a single cutting wheel or a spaced pair of coaxial cutting wheels, a housing 42 encompassing said cutting means and having a mouth lying flush with a workpiece in use and extraction means (26 fig 4) to remove debris from within the housing to a collector. The housing may have at least one pivotable inner part 44 and both inner and outer parts may be adjustable by means of arcuate slots (78, 90 fig 2). The inner part may have a flange 86 to engage the workpiece. The extraction means may be an impellor within an impellor chamber 28. The impellor and cutting means may have parallel and offset axes and be driven by a drive means, shafts of the two being joined by a drive belt.

Description

CUTTING MACHINE This invention relates to machines for cutting into workpieces, more especially walls, for example of masonry, brickwork or blockwork. Machines according to the invention may be suitable for chasing a groove in a wall, or may be suitable for cutting right through a wa'l, for example to form a door or a window opening.

One problem with known machines of a kind to which this invention relates is that they either have no provision at all for the collection of dust and debris produced during cutting, or that the collection of dust and debris involves the use of external equipment, such as a vacuum cleaner, to which the machine must be connected. The known machines therefore allow the escape of dust and debris into the ambient atmosphere, or are inconvenient to use as external equipment is required.

Machines which allow dust and debris to escape also tend to allow it to collect in their drive motors and thereby cause problems.

Broadly in accordance with the present invention there is provided a cutting machine, comprising cutting means arranged to penetrate into a workpiece, drive means arranged to effect rotation of the cutting means, a confinement housing encompassing the cutting means and having a mouth which is arranged to lie flush against a surface of the workpiece which is being cut, and extraction means arranged for the removal of debris from the confinement housing to an outlet arranged for connection to a debris collector.

Preferably, at least part of the confinement housing is pivotable in order that the mouth of the housing can be maintained flush against the surface which is being grooved.

This arrangement allows a problem with known machines to

be overcome. This is that it is difficult to make a cut in a well near the floor, and more especially near the ceiling. This is because it is difficult to keep the mouth of the known machine flush against the surface of the wall at low and especially at high levels. In order to do this one has to lower the known machine or raise the mac'ne so that its longitudinal axis is maintained substantially perpendicular to the wall surface. The arrangement just referred to overcomes this problem by allowing the pivotable part of the confinement housing to remain flush against the wall whilst the remainder of the machine is pivoted relative thereto as the machine approaches the top or bottom of the wall.

In a preferred embodiment, the confinement housing comprises an outer housing and an inner housing which are relatively pivotable.

In one arrangement, the inner housing is adjustable relative to the outer housing to define an adjusted position which determines the distance by which the cutting means protrudes from the inner housing and thus the maximum depth of cut.

In another arrangement, the inner housing is pivotable into the outer housing as the cutting means penetrates the workpiece, the distance by which the cutting means protrudes from the outer housing determining the maximum depth of cut.

Preferably, the inner housing comprises a pair of spaced parallel side walls joined by an arcuate wall, preferably with a flange extending along the length of one of the side walls at the mouth of the housing for engagement against the workpiece surface.

The cutting means can comprise a single cutting wheel or more than one cutting wheel. The cutting wheel or wheels can

be segmented or continuous and provision may be made for water cooling of the cutting means. A single cutting wheel will generally be used when it is desired to cut right through a workpiece ; a spaced pair of coaxial cutting wheels is particularly useful when chasing a groove in the surface of the workpiece. In other embodiments, the cutting means can be a single grinding wheel which is relatively wide.

Preferably the extraction means comprises an impeller which is rotatably driven by the drive means, the impeller advantageously being located in an impeller chamber which has an inlet in communication with the confinement housing and an outlet in communication with the outlet for connection to the debris collector.

In an advantageous arrangement, the impeller and the cutting means are rotatable about respective axes which are parallel to each other and offset relative to each other in a direction away from the surface of a workpiece being cut.

This allows a further advantage to be achieved in that the axis of the cutting means can be brought very close to the workpiece surface which is being cut.

In a preferred arrangement, the cutting means comprises one or more cutting wheels mounted on a first shaft and the impeller is mounted on a second shaft, the second shaft being driven by the drive means and the shafts being joined by a transmission whereby the first shaft is driven by the second shaft.

Conveniently, the transmission comprises a respective pulley wheel on each shaft and a drive belt extending around the pulley wheels.

In order that the invention may be more fully understood, two presently preferred embodiments of the cutting machine in

accordance with the invention will now be described by way of example and with reference to the accompanying drawings. Tn the drawings: Fig. 1 is a side view of a first cutting machine, partly broken away; Fig. 2 is a view of the cutting machine of Fig. 1, shown from the other side; Fig. 3 is a partial perspective view of the cutting machine of Figs. 1 and 2, showing more details of the cutting mechanism; Fig. 4 is a detailed view of the cutting machine of Figs.

1,2 and 3 showing details of the impeller within the housing; Fig. 5 is a side view of part of a second cutting machine, partly broken away; and Fig. 6 is a perspective view from the other side of the part-machine shown in Fig. 5.

Referring first to Figs. 1 to 4, the cutting machine, which is indicated generally at 10, comprises an electric motor housing 12, to the rear end of which is connected a handgrip 14, from which extends a connecting lead 16 to a power supply for the motor. The motor is preferably mains powered and is adapted to be connected for example to a 250V AC supply. A switch mechanism is incorporated within the handgrip 14 and is operated by a trigger 18 in the underside of the handgrip. This enables the user of the machine to turn the motor on and off. The motor housing 12 is connected to a gearbox 20, from which extends an upwardly directed handle 22, so that the user can grip the handle 22 with one hand and the handgrip 14 with the other hand when using the machine.

The gearbox 20 has an output shaft 24 which is perpendicular to the output shaft of the motor. An impeller

26 (Fig. 4) is mounted on the gearbox output shaft 24 and is thus driven by the motor to rotate in an anti-clockwise direction as viewed in Fig. 4. The impeller 26 is mounted on the gearbox output shaft within an impeller chamber 28 which is secured to one side of the gearbox 20. The impeller 26 is mounted for rotation between two spaced parallel walls of the impeller chamber 28. The impeller 26 comprises a circular plate 30 to which are fixed a plurality of spaced, radially extending blades 32, as shown in Fig. 4. On rotation, the impeller 26 draws air and debris created in the use of the machine from a central inlet 34 of the impeller chamber 28 located around the gearbox output shaft 24 and directs it to an outlet 36 of the chamber. The outlet 36 is rectangular in cross-sectional shape and is shown fitted with a cuff 38 which has a circular cross-section outlet 40. The outlet of the cuff can be connected to a conventional flexible hose to direct dust and debris to a suitable collector.

The impeller chamber 28 is closed outwardly of the impeller by a closure plate 31 which constitutes one of the spaced parallel walls of the chamber 28.

The inlet 34 of the impeller chamber 28 is in communication with the head of the machine which comprises the cutting mechanism. The head of the machine comprises an outer cutter housing indicated generally at 42, and an inner cutter housing which is indicated generally at 44. The housings will be described in more detail hereinafter. Within the cutter housings 42,44 is mounted the cutting mechanism which is here shown as two cutting wheels 46 mounted in spaced parallel configuration and each comprising a segmented wheel with slots 48 between the individual segments. The cutting wheels 46 are mounted on a drive shaft 50 which defines a cutting wheel

axis. This axis extends parallel to the axis of the gearbox output shaft 24. The cutting wheels 46 are driven from the motor by a transmission which comprises a driving pulley 52 on the gearbox output shaft 24, a drive belt 54 and a driven pulley wheel 56 on the cutting wheel drive shaft 50. An adjustable tensioner 58 is provided for the belt 54 and comprises a jockey pulley 60 mounted for rotation on a bracket 62 which is pivotally mounted on the inside of the impeller housing 28. The jockey pulley 60 is pressed into contact with the belt 54 by a screw 64 which passes through a threaded bore in the wall of the housing 28. By rotation of the screw 64 the tension in the belt 54 can be adjusted.

The gearbox output shaft 24 also carries a friction clutch 66 (Fig. 4) which incorporates a pre-loaded spring.

The driving pulley 52, belt 54 and tensioner 58 are mounted outwardly of the closure plate 31. The machine housing outwardly of the transmission is closed by a further cover plate 61 which is secured in position by a series of screws 63.

The outer cutter housing 42 and inner cutter housing 44 which together constitute a housing for collecting debris produced by the cutting wheels 46 which are arranged as two relatively moveable parts. The outer cutter housing 42 comprises two spaced parallel side walls 68 and 70. These side walls 68,70 are each part-circular in shape, each being defined by an arcuate edge extending over about 1200 of arc and a chord extending between the ends of the arcuate edge. The side walls 68,70 are joined by a part-circularcylindrical curved wall portion 72. The curved wall portion 72 is in sliding contact with two complementary arcuate surfaces on the inside of a pair of respective brackets 74

which are secured to the impeller housing 28 and serve to guide and position the outer cutter housing 42. Between the interior curved surface of the brackets 74 and the curved wall portion 72 is provided a layer of felt or like material to seal the space between the respective curved surfaces. The outer side wall 70 of the outer cutter housing 42 includes an arcuate extension portion 76 which defines an arcuate slot 78 which is centred on the axis of pivotation of the outer cutter housing 42 on the axis of the cutting wheels 46. An adjustment screw passes through the slot 80 into a threaded socket in the impeller housing 28. This screw carries a thumb wheel 80 which can be rotated in order to clamp the outer cutter housing 42 in a selected rotational position relative to the impeller housing 28. The mouth of the outer cutter housing 42 is of sufficient arcuate extent to register with the inlet opening 34 of the impeller housing in any attainable relative position of the outer housing 42 relative to the impeller housing 28.

The inner cutter housing 44 comprises a first side plate 82 and a second side plate 84, the shape of which can be seen most clearly from Fig. 3 of the drawings. The first side plate 82 has a flange 86 which extends perpendicular to the plane of the side plate along its length. The second side plate 84 is smaller in size than the first side plate 82 and only has about one quarter or one third of the vertical extent of the latter. This defines an access passage when the mouth of the cutting head is flush against a wall, so that air can be drawn into the head by the action of the impeller to carry dust and debris away from the cutting wheels. The inner cutter housing 44 is pivotally mounted on a bolt 88 which passes through a hole in the outer side wall 70 of the inner

cutter housing 44 adjacent to where the arcuate and straight edges of the side plate meet. The side wall 70 of the outer cutter housing 42 is also provided with an arcuate slot 90 (Fig. 2), through which passes the stem of a bolt which has a head 92. The bolt is secured in a socket in the first side plate 82 of the inner cutter housing 44. The purpose of the bolt having head 92 is to enable the bolt to be turned by hand in order to secure the outer and inner cutter housings 42,44 in a selected relative position between limits determined by the ends of the arcuate slot 90.

Adjustment of the inner housing 44 relative to the outer housing 42 changes the extent by which the cutting wheels 46 protrude beyond the flange 86 on the inner cutter housing 44, i. e. to change the depth of cut. When the inner cutter housing 44 is pivoted fully inside the outer cutter housing 42, then, as shown in Fig. 1, the cutting wheels 46 protrude to their maximum extent. As the inner housing 44 is pivoted out from the outer housing 42, so the cutting wheels 46 protrude less and less. The depth of cut of the cutting wheels 46 is thereby determined and can be chosen and set.

The arrangement of inner and outer housings allows easy removal of the inner housing to access the wheels for change of them and to adjust their spacing.

The machine of this first embodiment is intended for cutting or chasing a groove in a surface of a workplace, for example a wall of, for example, brickwork, blockwork or masonry. The width of the groove is determined by the spacing of the two cutting wheels 46. The depth of the groove is determined by the amount by which the cutting wheels 6 protrude from the outer housing 42 when the flange is brought into contact with the surface of the workpiece.

It should be noted that the axis of the cutting wheels 46 is very close to the surface of the wall which is being chased, by virtue of the configuration of the axis of rotation of the cutting wheels 46 being offset from the axis of the output shaft 24 of the gearbox 20 and the transmission being interposed between the gearbox and the cutting wheels.

Because the inner cutter housing 44 is pivotable, within the limits defined by the length of the arcuate slot 90, this makes it very much easier to chase a groove in a vertical wall both near the ceiling and near the floor. At both these extremes, the user can make use of this pivotal movement to maintain the flange 86 and thus the mouth of the cutter housing, in contact with the wall surface without having to raise and lower the machine to such an extent that the main longitudinal axis of the machine is kept horizontal. The main longitudinal axis of the machine can be inclined upwards or downwards while still keeping the mouth of the cutter housing flush against the wall which is being chased. This both makes it easier to use the machine and also means that there is less likelihood of dust and debris escaping into the ambient atmosphere.

It should also be noted that, in order to collect the dust and debris generated during use of the machine, the cuff 40 is simply connected to a length of flexible hose of suitable diameter, the other end of which is placed at suitable location for collection or dispersion of the dust and debris. The dust and debris is blown through the hose by the impeller 26 and the use of external equipment such as a vacuum cleaner is avoided.

The second embodiment shown in Figs. 5 and 6 of the drawings is a machine which has a single cutting wheel for

cutting right through brickwork or masonry, for example, when it is desired to form a window opening.

In general, reference numerals increased by"100" relative to the reference numerals used in Figs. 1 to 4 are used in Figs. 5 and 6 to indicate machine parts corresponding to those of Figs. 1 to 4.

The machine 110 shown in Figs. 5 and 6 is shown with its electric motor housing, handgrip, gearbox and handle omitted.

These parts however correspond to the same parts of the first machine described above.

The machine comprises an outer housing 142 which is formed from two parallel metal sheets which are joined by inwardly-directed flanges which form a closed periphery of the housing except at its mouth when the flanges 186 are directed outwardly along each edge of the mouth which is thus in the form of a narrow rectangular slot.

The cutting wheel is a single wheel 146 which is of larger diameter than the cutting wheels of the first embodiment, the wheel 146 being shown in outline only in Figs.

5 and 6.

The wheel 146 is mounted for rotation in the housing 142 on a drive shaft 150, on which a driven pulley wheel 156 is mounted. The driven pulley wheel 156 forms part of a transmission which comprises a drive belt (now shown), a belt tensioner 158 having a jockey pulley 160 and a driving pulley (also not shown).

The driving pulley is mounted on the output shaft of the gearbox, on which shaft an impeller 126 is also mounted. The gearbox is attached to the outer housing 142 by four bolts passing into threaded sockets 111. It will be noted that, in this embodiment, the transmission is located on the same side

of the cutter housing 142 as the motor, the driving pulley being located on the output shaft of the gearbox between the gearbox and the impeller 126.

The impeller 126 is shown in dashed lines in Fig. 5 and is located in an impeller chamber formed in a housing 128 which has an inlet which is located around the gearbox output shaft and is in communication with the inside of the impeller chamber. The impeller chamber has an outlet 138 which is rectangular in section and to which a cuff such as that shown in Fig. 1 can be attached for connection to a hose as described above.

The inner housing 144 of this embodiment is mounted within the outer housing 142 and pivots about the drive shaft 150 of the cutting wheel. The guard consists of two spaced parallel plates 182, 184 which have the shape of sectors of a circle. The plates 182, 184 are joined between their curved edges by the curved wall 185 which closes the gap between the plates. Between the plates 182, 184 at the outer end of the curved wall a guide wheel 204 is mounted to facilitate pushing of the inner housing 144 back into the housing as the machine is brought into contact with the surface of a workpiece which is to be cut. The inner housing may be spring-loaded towards its outer position if desired.

The machine described with reference to Figs. 5 and 6 works very similarly to that described with reference to Figs. 1 to 4 except that the cutting wheel penetrates further into the workpiece and can therefore cut all the way through many workpieces. The inner housing 144 is pushed back as the cutting wheel penetrates the workpiece until the flanges 186 on the outer housing 142 come into contact with the surface of the workpiece. The outer housing 142 then serves to confine the dust and debris in the same way as for the machine of Figs. 1 to 4, the dust and debris being blown by the impeller 126 through the hose connected to the outlet 138.

Upon initial penetration of the cutting wheel 146 into the workpiece, the inner housing 144 acts to confine dust and debris and to direct it into the outer housing 142.

Claims

CLAIMS : 1. A cutting machine, comprising cutting means arranged to penetrate into a workpiece, drive means arranged to effect rotation of the cutting means, a confinement housing encompassing the cutting means and having a mouth which is arranged to lie flush against a surface of the workpiece which is being cut, and extraction means arranged for the removal of debris from the confinement housing to an outlet arranged for connection to a debris collector.
2. A cutting machine according to claim 1, wherein at least part of the confinement housing is pivotable in order that the mouth of the housing can be maintained flush against the surface which is being cut.
3. A cutting machine according to claim 1 or 2, wherein the confinement housing comprises an outer housing and an inner housing which are relatively pivotable.
4. A cutting machine according to claim 3, wherein the inner housing is adjustable relative to the outer housing to define an adjusted position which determines the distance by which the cutting means protrudes from the inner housing and thus the maximum depth of cut.
5. A cutting machine according to claim 3, wherein the inner housing is pivotable into the outer housing as the cutting means penetrates the workpiece, the distance by which the cutting means protrudes from the outer housing determining the maximum depth of cut.
6. A cutting machine according to claim 3 or 4, wherein the inner housing comprises a pair of spaced parallel side walls joined by an arcuate wall, with a flange extending along the length of one of the side walls at the mouth of the housing for engagement against the workpiece surface.
7. A cutting machine according to any preceding claim, wherein the cutting means comprises a single cutting wheel.
8. A cutting machine according to any of claims 1 to 6, wherein the cutting means comprises a spaced pair of coaxial cutting wheels.
9. A cutting machine according to any preceding claim, wherein the extraction means comprises an impeller which is rotatably driven by the drive means.
10. A cutting machine according to claim 9, wherein the impeller is located in an impeller chamber which has an inlet in communication with the confinement housing and an outlet in communication with the outlet arranged for connection to a debris collector.
11. A cutting machine according to claim 9 or 10, wherein in the impeller and the cutting means are rotatable about respective parallel axes which are offset relative to each other in a direction away from the surface which is cut by the machine.
12. A cutting machine according to claim 11, wherein the cutting means comprises one or more cutting wheels mounted on a first shaft and the impeller is mounted on a second shaft, the second shaft being driven by the drive means and the shafts being joined by a transmission whereby the first shaft is driven by the second shaft.
13. A cutting machine according to claim 12, wherein the transmission comprises a respective pulley wheel on each shaft and a drive belt extending around the pulley wheels.
14. A cutting machine substantially as hereinbefore described with reference to Figs. 1 to 4 or Figs 5 and 6 of the drawings.