WO2018229563A1

WO2018229563A1 - Improved handheld motorized cutting device and relative accessory

Info

Publication number: WO2018229563A1
Application number: PCT/IB2018/052758
Authority: WO
Inventors: Vincenzo Montoli; Luigi Casartelli
Original assignee: Brevetti Montolit S.P.A.
Priority date: 2017-06-12
Filing date: 2018-04-20
Publication date: 2018-12-20
Also published as: EP3638471B1; CN111225775B; CN111225775A; ES2923386T3; EP3638471A1

Abstract

It is disclosed an accessory equipment for a motorized handheld cutting device, comprising a hub to be coupled to a motor body of said device, coaxially to a motor shaft (la), and a supporting surface suitable for resting on a surface of a material to be cut, wherein said hub (6, 60) is integral with an inner ring of a rotating bearing (4) having a central hole adapted to be fitted coaxially on said motor shaft (la) of said motorized cutting device, and in that said supporting surface is constituted by a support ring (5) which is integral in rotation to an outer ring of said rotating bearing (4).

Description

IMPROVED HANDHELD MOTORIZED CUTTING DEVICE AND RELATIVE AC^¬ CESSORY

DESCRIPTION

FIELD OF THE INVENTION

The present invention relates to a handheld motorized cutting device or tool, in particular a device with a rotat^¬ ing cutting blade, provided with an auxiliary accessory. BACKGROUND ART

As has long been known, in cutting hard materials such as tiles and stone slabs, it is often necessary to use motor rotating blade cutting devices of the handheld type. In par^¬ ticular, these devices comprise a freehand gripping motor unit, which carries at its end a free circular blade, gen^¬ erally a thin diamond disc, brought into rotation by the motor unit .

The motor unit is inserted into a casing, provided ex^¬ ternally with on/off switches, with handles to improve the retention by the operator and possibly with a safety blade protective shield.

This device is light and not bulky, which is much appre^¬ ciated because it promotes portability and does not tire the operator. Since it is very easy to use, however, this type of cutting tool lends itself to incorrect use, especially in the precarious conditions of a construction site.

Typically, to make a cut, the tile or stone slab is fixed cantilevered on a support, for example by means of a clamp (or sometimes simply by the pressure of a foot), and then the operator performs cutting by starting the electric motor and bringing the rotating diamond disc to make the cut in the cantilevered part of the material.

The problem presented here - particularly when the cut is longer than a few centimetres - is that the guide of the motorized device, for example along a line previously drawn on the tile surface, is difficult and leads to a not per^¬ fectly straight cut. The difficulty is inherent in the fact that the device is relatively light compared to the stresses that are transferred by the rotating blade, it must be sup- ported freehand moving with the whole body and keeping it at a correct distance from the material plane to cut through the whole depth of the slab, but without abutting the surface of the material (because it could cause damage) . Without lateral guidance and without the possibility of support, it is difficult to perform perfectly controlled cuts.

Cutting devices operated freehand by the operator, which provide a support on the surface to be cut, are already available on the market: these are the disc saws for cutting small-thickness timber. These devices include, especially for safety reasons, a cage which - mounted on the casing of the drive motor, centred on the shaft of the toothed disc saw - is provided with an adjustable flat frame, intended to rest on the surface of the wood plane to be cut. This frame, which comprises a cutout through which the disc saw passes, is adjustable in position, so as to predetermine the height of the cutting disc with respect to the material plane.

However, such an arrangement cannot be transferred as it is to the field of cutting of slabs of hard material, because the vibrations of the tool frame would cause unwanted micro- scratches on the finished surface of the slabs. As a conse^¬ quence, the motorized tools are still used freehand, in a floating way, with the risk of making cuts that are not perfectly straight and therefore not acceptable for a good finishing job.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an accessory for a handheld, circular blade motor^¬ ized cutting device which allows to obtain a considerable improvement, with respect to the prior art, in the execution of perfectly controlled cuts. This object is achieved by the features mentioned in claim 1. The dependent claims describe preferred features of the invention.

In particular, according to a first aspect of the inven^¬ tion, an accessory is provided for a motorized and handheld cutting tool, comprising a hub to be coupled to a motor body of said tool, coaxially to a motor shaft, and a supporting surface suitable for resting on a surface of a material to be cut, wherein said hub is integral with an inner ring of a rotating bearing having a central hole adapted to be in^¬ serted coaxially on said motor shaft of said motorized cut^¬ ting tool, and said supporting surface is constituted by a support ring which is integral in rotation to an outer ring of said rotating bearing.

Advantageously, the axial size of said support ring is lower than the axial size of at least one of said inner ring of the rotating bearing. Preferably, the axial size is less than 1 cm, preferably less than 0.8 cm.

According to a singular aspect, the support ring has at least said peripheral surface made of either an anti-abra^¬ sion material or a high-friction soft material.

According to a first variant, the hub has an axial threaded hole and at one end thereof it is provided a cir- cular centring protrusion for a cutting disc.

According to another variant, a clamping flange is also provided, consisting of a cylindrical centring body and a flat head flange, crossed centrally by a threaded hole.

According to another aspect, a handheld motorized cut- ting tool assembly is provided comprising a hand-held casing containing an electric motor provided with a motor shaft, projecting to the outside of the casing, provided with a base abutment surface and a threaded end portion, a cutting disc and a clamping flange being closely locked on said motor shaft, characterized in that an accessory as described above is also closely locked between said clamping flange and said abutment surface.

According to a variant, the clamping flange consists of a cylindrical centring body and a flat head flange, crossed centrally by a threaded hole. Preferably, an outer diameter of the cylindrical centring body is equal to the one of a central hole of said cutting blade.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will anyhow be more evident from the following detailed descrip^¬ tion, given by mere way of non-limiting example and illus^¬ trated in the accompanying drawings, wherein:

fig. 1 is an overall perspective view of a motorized cutting tool provided with the accessory according to a first embodiment of the invention, without a cutting disc;

fig. 2 is a view similar to Fig. 1, with a mounted cutting disc;

fig. 3 is a view similar to that of fig. 2 according to a different perspective;

fig. 4A is a perspective exploded view of the embodiment of fig . 2 ;

fig. 4B is a view similar to that of fig. 4A of a different embodiment of the invention; and

fig. 5 is a perspective exploded view of the accessory according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the appended figures, an accessory according to the invention is well represented in its entirety applied to a cutting device which, as it is known per se, is not illus^¬ trated in each single detail.

In fact, a rotary blade handheld cutting device comprises, in a per se known manner, a casing 1, inside which an electric drive motor (not shown in the drawings) is ar^¬ ranged which ends with a motor shaft la, on which standard tools are applied.

Typically, the end of the motor shaft la which protrudes out of the casing 1 has a calibrated cylindrical section on which a stop flange is fit, integral in rotation, provided with a cylindrical protrusion which acts as a coupling and centring means for a central hole 2a of a cutting disc 2 (for example a diamond disc) ; the shaft la then terminates with a standard threaded portion, on which a clamping flange lb adapted to hold the cutting disc 2 against the abutment flange is designed to be engaged, so as to prevent any rel^¬ ative movement between the disc and the shaft la.

Most of the cutting disc 2 rotates freely overhanging from the motor shaft and only a protective shield 3 is pro^¬ vided, on the side facing the operator, to protect against any splinters projected from the disc.

According to the present invention, it is also envisaged to install a support accessory on the motor shaft la, which provides a ring idle with respect to the shaft la, which acts as a support on a surface of the material to be cut.

In particular, the support accessory consists of a bear^¬ ing body 4 on whose ring or outer track a support ring or wheel 5 is integral.

The bearing 4 is dimensioned in such a way that it can be fit centred on the shaft la. Preferably, the inner ring or track of the bearing 4 is integral with a hub 6 provided with a central hole, designed to house the threaded end portion of the motor shaft la.

This central hub 6 is coupled to the inner ring of the bearing 4, for example, on one side, with an abutment surface 6a and, on the other, by a Seeger^™ circlip 6b.

According to a first embodiment of the invention (Fig. 4A) , the hub 6 has a threaded central hole 6c of a diameter equal to the nominal diameter of the motor shaft la. At one end of the hub 6, manoeuvring holes 6' are also provided.

Moreover, at the end facing the cutting disc 2, the hub 6 has a circular protrusion 6r (visible only in fig. 1) on which the central hole 2a of the cutting disc 2 is centred, typically the hole 2a being of diameter greater than the diameter of the motor shaft la.

For the assembly, the abutment flange (supplied as stand^¬ ard equipment of the tool) is removed from the motorized device and, using an appropriate tool (not shown) to act on the holes 6', the hub 6 is tightened strongly against the abutment surface of the motor shaft la.

The support ring 5 integral with the outer ring of the bearing 4 has a modest thickness (axial size) , for example less than 1 cm or preferably 0.8 cm, so that the motor shaft la can pass through the hole 6c and protrude by a sufficient extent (as shown in fig. 1) to be able to still house on its axis both a cutting disc 2, centred on the protrusion 6r, and a relative clamping flange lb (figs. 2 and 3) intended to clamp closely the disc 2 against the hub 6 of the bearing 4, which in turn is integral in rotation with the motor shaft la.

As shown in fig. 1, the hub 6 of the bearing 4 preferably has a width greater than that of the outer ring and of the support ring 5 integral with it, so that the two lateral bearing surfaces of the hub - on one side against the abut- ment surface of the shaft la, on the other side against the cutting disc 2 which is in contact with it - are external to the two laying planes of the outer ring of the bearing and of the support ring 5. In this way, the support ring 5 remains free to rotate idly in close proximity to the side surface of the cutting disc 2.

Due to the modest thickness of the accessory according to the invention, once assembled, the cutting disc 2 is in a position along the motor shaft la not too far from the original design, so as to avoid interference with the pos^¬ sible protective shield 3.

After fitting it on the shaft la and clamping it in place with the cutting disc 2 and the clamping ring lb, the bearing 4 is thus on one hand, with its inner ring locked between the abutment of the motor shaft and the disc 2 and, on the other hand, with its outer ring being freely rotating. Ac^¬ cordingly, the accessory remains centrally locked and inte^¬ gral with the motor shaft la, so as to adequately transmit the rotary motion to the cutting disc 2, while it has the support ring 5 in idle condition, which therefore can also remain stationary while the inner ring rotates.

The support ring 5 has an external radius which is smaller than the radius of the cutting disc 2 of an extent equal to the working band of the disc, for example of 2-3 cm .

With this configuration, the support ring 5 can be used as a support means on the surface of the material to be cut, by causing the blade of the disc 2 to penetrate in the material by a measure equal to the aforementioned working band .

This therefore allows the operator to work equally free^¬ hand for guiding cutting, nevertheless placing the support ring 5 of the tool on the surface to be cut in close proximity to the cutting line, due to the fact that the support ring 5 remains idle with respect to the rotation of the cutting disc 2.

So, the operator, no longer having to make the effort to support the motorized device at a certain height, can con^¬ centrate his intervention and his attention to guide the cutting disc along the specially arranged cutting line.

For this supporting function, at least the outer surface of the support ring 5 must preferably have a finish such as not to cause scratches or marks on the finished surface of the material to be cut. To this purpose, the whole support ring 5 can be made of plastic material, for example of a low-friction material such as Teflon™, or it can be made of metallic material (for example steel or aluminum alloy) coated with a softer material. To avoid scratching the sur^¬ face of the material to be cut, the periphery of the support ring must have either an anti-abrasion material (such as Teflon™) or a high friction material surface, so that the support ring does not ideally slide but rather tends to roll, at the advancement of the tool in the cut, without marking the surface.

For some models of motorized device, in which there is a risk that the accessory according to the invention inter- feres with the protective shield 3 or with the casing 1, it is preferable to keep the standard abutment flange in posi^¬ tion. In this case, the thickness of the hub 6 would end up excessively reducing the length of the threaded end of the shaft la.

Therefore, according to an alternative embodiment (fig.

4B) , the central hub 60 on which the bearing 4 is mounted has a central hole 61 with a larger diameter than that of the motor shaft la, in particular a hole corresponding to the standard hole of circular blades (for example, with a 22 mm diameter) . In this way, the hub 60 can be centred on a standard abutment flange If of the motorized tool.

In this case, the support accessory according to the invention further comprises a modified clamping flange 62, consisting of a cylindrical centring body 62 ' and a flat head flange 62 ' ' , centrally crossed by a threaded hole 63 adapted to engage with the threaded portion of the motor shaft la.

The outer diameter of the cylindrical centring body 62 ' is equal to the central hole 2 of the circular blade 2. In this way, the clamping flange 62 acts both as a centring element of the blade 2, acting from the inside of the hole 2a, and as a clamping element of the blade 2 against the hub 60.

The cylindrical centring body 62' has a size such that it extends inside the hole 61 of the hub 60, so as to be coupled for a significant length with the threaded portion of the shaft la. The extension of the cylindrical body 62' is nevertheless less than the depth of the hole 61.

It is to be understood, however, that the invention is not limited to the particular configurations illustrated above, which constitute only non-limiting examples, but that numerous variations are possible, without departing from the scope of the invention as defined by the following claims.

For example, although a cutting tool has always been shown in which the support ring is located between the motor shaft and the cutting disc, it is also possible to foresee - in some working conditions - that the operator prefers to mount the support ring 5 between the clamping flange and the cutting disc 2.

Again, although the support ring 5 has been shown as a separate piece from the bearing 4, it is not excluded that the support ring consists of a circular coating layer of the outer track of the bearing 4 itself.

Claims

1. Accessory equipment for a motorized and handheld cutting device, comprising a hub to be coupled to a motor body of said device, coaxially to a motor shaft (la), and a supporting surface suitable for resting on a surface of a material to be cut, characterized in that said hub (6, 60) is integral with an inner ring of a rotating bearing (4) having a central hole adapted to be fitted coaxially on said motor shaft (la) of said motorized cutting device, and in that said supporting surface is constituted by a support ring (5) which is integral in rotation to an outer ring of said rotating bearing (4) .

2. Accessory equipment as in 1, wherein the axial size of said support ring (5) is lower than the axial size of at least said inner ring of the rotating bearing (4) .

3. Accessory equipment as in 2, wherein said axial size is less than 1 cm, preferably less than 0.8 cm.

4. Accessory equipment as in 1, 2 or 3, wherein said support ring (5) has at least said peripheral surface made of an anti-abrasion material or a high-friction soft mate^¬ rial .

5. Accessory equipment as in any one of the preceding claims, wherein said hub (6) has an axial threaded hole (6c) and at one end thereof there is provided a circular centring protrusion (6r) .

6. Accessory equipment according to any one of claims 1-5, wherein a clamping flange (62) is also provided, con^¬ sisting of a cylindrical centring body (62') and a flat head flange (62''), crossed centrally by a threaded hole (63) .

7. Handheld motorized cutting tool assembly comprising a hand-held casing (1) containing an electric motor provided with a motor shaft (la), projecting from the outside of the casing, provided with a base abutment surface and a threaded end portion, a cutting disc (2) and a clamping flange being closely locked on said motor shaft (la), characterized in that an accessory equipment as in any of the preceding claims is also locked between said clamping flange (la, 62) and said abutment surface.

8. Tool assembly as in 7, wherein said clamping flange (62) consists of a cylindrical centring body (62') and a flat head flange (62''), crossed centrally by a threaded hole (63) .

9. Tool assembly as in 8, wherein an outer diameter of said cylindrical centring body (62') is equal to a central hole (2a) of said cutting blade (2) .