CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to GB Patent Application No. 1906066.4, which was filed Apr. 30, 2019, and this application also claims priority to GB Patent Application No. 1917514.0, which was filed Nov. 29, 2019, the teachings of which are incorporated herein by reference.

FIELD

The present invention relates to a cutting device for cutting a pipe of a set diameter, in particular for cutting a plastic pipe.

BACKGROUND

Plumbing systems generally use copper or plastic piping, plastic being increasingly preferred due to its lower cost. The pipes are provided in a variety of lengths, which are then cut to the appropriate size for the system.

A known tool for cutting a plastic pipe is described in GB2457447. The tool comprises a body having a bore for receiving a cylindrical conduit, a slot extending from an external surface of the body to the bore and a cutting blade extending into said bore along a plane extending at right angles to an axis through the body. The slot tapers so that its width progressively diminishes with distance from the external surface of the body to the external circumference of the bore. The body is formed by a first segment on one side of the slot, which is generally rigid and inflexible and a hollow second segment on the other side of the slot, which is resilient and flexible. This causes flexing and resilience so that the conduit is urged against the blade, allowing the cutting of the blade.

Effective cutting by the tool requires the application of a substantial amount of force to the body from the user. In addition, the blade of the tool is exposed when not in use; unless a blade cover is also used. This can result in injury to a user.

The present invention seeks to provide an improved cutting device.

DESCRIPTION

The present invention relates to a cutting device for cutting a pipe of a set diameter. The cutting device has an annular support body for engaging a pipe to be cut, the annular support body formed of a rigid material and comprising a blade-bearing portion and a non-blade-bearing portion, the blade-bearing portion being secured to the non-blade-bearing portion by way of a hinge mechanism. The hinge mechanism allows the two portions to be movable between an open position, in which the pipe can be inserted and removed from the body, and a closed position, in which the pipe, once inserted, is engaged by and axially aligned with the annular support body. In the closed position, the blade-bearing portion of the annular support body opposes the non-blade bearing portion, such that in use the urging of the two portions towards the closed position urges the pipe against the blade so that rotation of the cutting device around the pipe cuts the pipe.

According to a first aspect there is provided a cutting device for cutting a pipe of a set diameter, the cutting device comprising an annular support body defining an axial space into which a pipe to be cut can be inserted, the annular support body formed of a rigid material and comprising a blade-bearing portion and a non-blade-bearing portion, the blade-bearing portion being secured to the non-blade bearing portion by a hinge mechanism allowing the two portions to be movable between an open position, in which the pipe can be inserted and removed from the body, and a closed position, in which the pipe, once inserted, is engaged by and axially aligned with the annular support body, wherein a part of the blade-bearing portion spaced from the hinge mechanism comprises a blade that protrudes radially inwards of the annular body, such that in use the urging of the two portions towards the closed position urges the pipe against the blade so that rotation of the cutting device around the pipe cuts the pipe.

The blade of the blade-bearing portion is not located at or fixed to the hinge mechanism, i.e. the blade is fixed to a part of the blade-bearing portion other than the part comprising the hinge mechanism.

The hinge mechanism may comprise or be formed by a cylindrical shaft. Alternatively, the hinge mechanism may comprise two or more pegs configured to be received by two or more hinge recesses. The two or more pegs may be cylindrical. In some embodiments, the non-blade-bearing portion comprises the two or more pegs and the blade-bearing portion comprises the two or more hinge recesses. In some embodiments, the blade-bearing portion comprises the two or more pegs and the non-blade-bearing portion comprises the two or more hinge recesses.

The use of pegs can be advantageous as it provides fewer separate components to the cutting device. This can make manufacture and repair easier, cheaper and more efficient.

It will be appreciated that by “rigid” it is meant that the material offers very little resilience and does not deflect appreciably when forces of the magnitude required to operate the device are applied.

The inventors envisage that the cutting device may be used for cutting plastic pipes.

The location of the blade-bearing portion opposite to the non-blade-bearing portion ensures that the portions can be moved to the closed position to prevent exposure of the blade, and potential injury, when not in use.

As the skilled person will appreciate, annular refers to a ring shape, i.e. a circular band enclosing a space. The annular support body thus comprises a cylindrical outer surface and a cylindrical inner surface between which is defined a circular band. The cylindrical inner surface encloses the axial space such that in use at least a portion of the cylindrical inner surface engages the pipe to be cut. The cylindrical outer surface allows the cutting device to be handled by the user.

It will be understood that the pipe of a set diameter has a diameter, which is capable of fitting into the diameter of the axial space defined by the cylindrical inner surface. However, when the pipe is first inserted into the device it is prevented from fully entering the axial space by the blade, as the blade extends into the space.

In the context of the present invention, the diameter of the annular support body or the axial space enclosed by the annular support body will be understood to refer to the diameter as measured in a direction orthogonal to the engagement axis.

The width of the annular support body will be understood to be the depth of the annular support body as measured in a direction aligned with the longitudinal axis of the annular support body. For the avoidance of doubt, and as used herein, “the longitudinal axis of the annular support body” refers to the axis, which is aligned with the axis of the pipe when in use.

When the annular support body is not engaging a pipe and when the portions are closed, an end of the non-blade-bearing portion distal to the hinge mechanism abuts an end of the blade-bearing portion of the annular support body. This generates a continuous annular body and defines the diameter of the axial space enclosed by the annular support body.

When the annular support body is engaging a pipe and in the closed position, the distal end of the non-blade-bearing portion does not abut the end of the blade-bearing portion of the annular support body, since the pipe is prevented from fully entering the space defined by the cylindrical inner surface by the blade. This prevents the non-blade-bearing portion from closing against the blade-bearing portion of the annular support body. This enables the user to push against either portion, or both portions, with the desired force to urge the pipe against the blade, resulting in cutting of the pipe. Advantageously, this results in fine control of the cutting of the pipe while only requiring the application of limited force to a small portion of the annular support body. This improves ease of use.

It will be appreciated that when a pipe is engaged by the annular support body and the portions are in the closed position, although the non-blade-bearing portion does not abut the end of the blade-bearing portion of the annular support body, the portions are closed sufficiently to secure the pipe by the annular support body, i.e. the portions act as gates to prevent the pipe from falling out of the annular support body. The accidental removal of the pipe is thereby avoided.

It will be understood that the cylindrical inner surface of the annular support body may be considered as comprising a part-cylindrical inner surface of the non-blade-bearing portion and a part-cylindrical inner surface of the blade-bearing portion. It is further understood that any reference herein to the cylindrical inner surface of the blade-bearing portion or the non-blade-bearing portion refers to the part-cylindrical inner surface of that portion. In this way, the terms part-cylindrical inner surface and cylindrical inner surface may be used interchangeably when in reference to the blade-bearing and non-blade-bearing portions.

In some embodiments, the part-cylindrical inner surface of the blade-bearing portion may have a radius which differs from a radius of the part-cylindrical inner surface of the non-blade-bearing portion. In such embodiments, the cylindrical inner surface of the annular support body may still be considered substantially cylindrical.

In some embodiments, the radius of the cylindrical inner surface of the blade-bearing portion is less than or equal to the radius of the pipe to be cut, i.e. an interference fit. The radius of the cylindrical inner surface of the non-blade-bearing portion may be the same as the radius of the pipe to be cut. In other words, the cylindrical inner surface of the blade-bearing portion may have a tight fit around the pipe, as compared to the fit around the pipe of the cylindrical inner surface of the non-blade-bearing portion.

In some embodiments, the blade-bearing portion of the annular support body comprises a part-cylindrical inner surface and the non-blade-bearing portion of the annular support body comprises a part-cylindrical inner surface. A radius of the part-cylindrical inner surface of the blade-bearing portion may be less than or equal to a radius of the pipe to be cut. A radius of the part-cylindrical inner surface of the non-blade-bearing portion may be less than or equal to the radius of the pipe to be cut. The radius of the part-cylindrical inner surface of the blade-bearing portion and the radius of the part-cylindrical inner surface of the non-blade-bearing portion may both be less than or equal to the radius of the pipe to be cut.

In other words, the part-cylindrical inner surface of the blade-bearing portion and/or the part-cylindrical inner surface of the non-blade-bearing portion may provide an interference fit. In other words, the part-cylindrical inner surface of the blade-bearing portion and/or the part-cylindrical inner surface of the non-blade-bearing portion may have a tight fit around the pipe

This interference fit is advantageous as it ensures the pipe is gripped firmly in operation, thereby preventing the pipe from moving laterally during use. Such lateral movement would hinder the ability of the device to provide a square and uniform cut. In addition, the interference fit pulls or pushes the tube into the blade-bearing portion without crushing or deforming the tube. This improves the ease of use and ensures a clean-cut, without unnecessarily damaging the tube.

In some embodiments, the radius of the cylindrical inner surface of the blade-bearing portion and/or the non-blade-bearing portion is greater than the radius of the pipe to be cut, i.e. a clearance fit. In other words, the cylindrical inner surface of the blade-bearing portion and/or the non-blade-bearing portion may have a loose fit around the pipe. It will be appreciated that although the cutting device is sized to fit a particular size of pipe, when a smaller diameter pipe is inserted the device may still work effectively. In other words, while the cutting device is made specifically for a certain pipe size, many similar but smaller pipes can also be cut.

In some embodiments, the blade-bearing portion and the non-blade bearing portion are both substantially semi-annular. In some embodiments, the blade-bearing portion forms a larger proportion of the annulus than the non-blade-bearing portion. In some embodiments, the blade-bearing portion forms a smaller proportion of the annulus than the non-blade-bearing portion.

For the avoidance of doubt and as used herein, “semi-annular” refers to half of the annulus when the annulus is divided along its diameter.

The annular support body is formed of a rigid material. Many rigid materials are tough and long lasting. Such materials ensure that the cutting device is durable. In addition, the rigid nature of the annular support body ensures a desired force can be exerted against the portions to urge the pipe against the blade, improving the cutting of the pipe.

Rigid materials are also readily accessible and easy to mould into the desired shape, for example by methods such as 3D printing. A suitable rigid material may include, but not be limited to, plastics. In some embodiments the annular support body comprises plastic, preferably a thermoplastic. Suitable plastics include, but are not limited to, polypropylene, polyoxymethylene (also known as Acetal), nylon, ABS (acrylonitrile butadiene styrene), or PET (polyethylene terephthalate) plastic. The plastic may comprise a glass-filled plastic, for example glass-filled nylon.

In some embodiments at least a portion of the cylindrical outer surface of the annular support body is ridged, i.e. comprises a plurality of ridges. The plurality of ridges may be aligned with the longitudinal axis of the annular support body. In some embodiments the cylindrical outer surface is ridged. Ridges improve the grip of the user. This improves handling of the device, and thus cutting and safety.

In some embodiments the diameter of the annular support body is greater than the width of the annular support body. This provides an ergonomic design, which is easy to handle or grip.

In some embodiments the blade comprises a linear cutting edge. The blade may comprise or consist of metal, for example steel. Suitable types of steel include, but are not limited to carbon steel, stainless steel, tool steel and high-speed steel.

In some embodiments, the linear cutting edge of the blade has one or both ends encased in the material of the blade-bearing portion of the annular support body, i.e. the linear cutting edge forms at least a partial geometric chord across the space enclosed by the cylindrical inner surface.

In some embodiments, the linear cutting edge of the blade has both ends encased in the material of the blade-bearing portion of the annular support body. In other words, the linear cutting edge forms a geometric chord across the space enclosed by the cylindrical inner surface.

In some embodiments, the linear cutting edge of the blade has only one end encased in the material of the blade-bearing portion of the annular support body. In other words, the linear cutting edge forms only a partial geometric chord across the space enclosed by the cylindrical inner surface. The linear cutting edge may form, for example, at least a half, a third, a quarter, a fifth or a different fraction of a geometric chord across the space enclosed by the cylindrical inner surface. The linear cutting edge may form no more than a half, a third, a quarter, a fifth or a different fraction of a geometric chord across the space enclosed by the cylindrical inner surface.

In embodiments in which the linear cutting edge forms only a partial geometric chord, it is understood that the blade is truncated such that it forms a triangular protrusion, from the cylindrical inner surface, with an exposed point or sharp corner. This configuration makes it easier for the blade to pierce a pipe in order to initiate cutting. This means that less force is required to close the portions of the cutting device. It also enables the blade to cut the pipe squarely, which is particularly useful when cutting pipes which are for use in push-fit arrangements, which are well known in the industry.

As used herein, “exposed point” will be understood to refer to the point of the triangular protrusion, which is not encased in the material of the blade-bearing portion, i.e. it is exposed to the axial space enclosed by the cylindrical inner surface.

The exposed point may have an inner angle of no more than 90°, no more than 80°, no more than 60°, no more than 50° or no more than 45°. In some embodiments the exposed point has an angle of 90°.

In some embodiments in which the blade forms a triangular protrusion (i.e. the linear cutting edge forms a partial geometric chord), the exposed point of the triangular protrusion may be offset with respect to the diameter of the annular support body which bisects the blade-bearing portion. In other words, the blade is angled such that the diameter that bisects the blade-bearing portion does not pass through the corner of the triangular protrusion. Such an offset means that the exposed point is optimally placed to pierce the pipe when the portions are urged towards the closed position.

In some embodiments in which the blade forms a triangular protrusion (i.e. the linear cutting edge forms a partial geometric chord), the exposed point of the triangular protrusion may be aligned with the diameter of the annular support body which bisects the blade-bearing portion. In other words, the blade is angled such that the diameter, which bisects the blade-bearing portion, passes through the corner of the triangular protrusion. Optionally, the blade may be angled such that the diameter that bisects the blade-bearing portion also bisects the inner angle of the exposed point.

In some embodiments, the linear cutting edge of the blade has neither end encased in the material of the blade-bearing portion of the annular support body. In other words, the blade forms a rectangular protrusion from the cylindrical inner surface.

The blade-bearing portion of the annular support body may comprise two pieces, optionally mirror-image pieces, coupled to one another at an interface generally perpendicular to the longitudinal axis. In some embodiments the blade is fixed by being clamped between the two pieces at the interface. The blade may be offset from one of the pieces relative to the other.

Either portion of the annular support body may comprise at least one external recess having a depth aligned with the longitudinal axis of the annular support body. In some embodiments the blade-bearing portion and/or the non-blade bearing portion of the annular support body comprises two opposing recesses, each recess having a depth aligned with the longitudinal axis of the annular support body. It will be appreciated that the support body portion has a wall separating the two opposing recesses. In some embodiments, both portions have the aforementioned recesses.

In some embodiments, the recess is or the recesses are enclosed, such that the portion forms an at least partially hollow structure. Hence, the portion(s) may be at least partially hollow with a closed sidewall. The use of a closed sidewall increases the strength of the non-blade-bearing portion and provides a device, which is simple to manufacture.

In some embodiments, the recess has or the recesses have a depth, which is substantially half the width of the annular support body.

In some embodiments, the recess has or the recesses have a depth, which is substantially narrower than the width of the annular support body. The depth of the recess or each recess may be at least 5, 10, 15, 20, 25, 30 or 45% of the width of the annular support body. The depth of the recess or each recess may be no more than 45, 40, 35, 30, 25, 20, 15, 10 or 5% of the width of the annular support body.

The non-blade-bearing portion of the annular support body may be unitary. This provides a device, which is simple to manufacture.

In some embodiments, the non-blade-bearing portion comprises a blade alignment indicator. The blade alignment indicator may provide an indication of the position of the blade. The blade alignment indicator may provide an indication of the position of the blade with respect to the width of the annular support body. The blade alignment indicator may be a visible mark or line which is aligned with the blade with respect to the width of the annular support body. The blade alignment indicator may be a visible line which runs parallel with the linear cutting edge of the blade. The blade alignment indicator may be embossed, engraved, painted, or otherwise applied to the non-blade-bearing portion.

The blade alignment indicator is advantageous to the user of the cutting device since it provides a means of easily aligning the cutting device to cut the tube at a desired position. It can be readily understood that, with a tube in place prior to cutting, it would be difficult for the user to identify the location of the blade. This could lead to uncertainty as to where the final cut would take place on the tube. In other words, the user may be unsure of the angle of the cut, or the position relative to the length of the tube. With the presence of a blade alignment indicator, the user is clear on where the blade is located and at what position the cut will be made with respect to the pipe.

In some embodiments, the device further comprises a removable guard for engagement with the annular support body when the cutting device is not in use. When engaged with the annular support body, the removable guard is aligned with the longitudinal axis of the annular support body. The guard engages with the cylindrical inner surface of the annular support body and the blade to cover and guard the blade. This prevents objects, for example fingers, from engaging with the blade and so reduces the risk of injury.

The guard may be cylindrical. In other embodiments the guard has an hourglass shape, the narrowest section of the hourglass aligning with the blade when engaged with the annular support body.

The removable guard may have a diameter equal to the diameter of the axial space enclosed by the annular support body. The removable guard may comprise or consist of a resilient material, for example a resilient plastic.

In some embodiments the guard comprises a groove, which aligns with the blade when engaged with the annular support body.

The guard may comprise a cap at both ends, the cap having a diameter greater than the diameter of the axial space enclosed by the annular support body. This secures the guard in the cutting device when in the closed position.

In some embodiments, each of the caps comprises a shelf. The shelf may extend longitudinally from the cap. The shelf may extend longitudinally inwards from the cap. The shelf may be circular. The shelf may have a radius smaller than the caps.

The shelf is advantageous as it ensures that the guard establishes an interference fit with the cutting device. This prevents unwanted lateral movement by the guard, which in turn prevents the guard from being inadvertently lost from the cutting device. In addition, the interference fit provided by the shelf assists in the retention of the guard while the two portions of the cutting device are in the open configuration. This prevents the guard from falling out of the cutting device while the two portions of the cutting device are opened.

In some embodiments, the radius of the shelf may be chosen such that the guard establishes an interference fit only with the blade-bearing portion. Alternatively, the radius of the shelf may be chosen such that the guard establishes an interference fit only with the non-blade-bearing portion. Alternatively, radius of the shelf may be chosen such that guard establishes an interference fit with both the non-blade-bearing portion and the blade-bearing portion.

In some embodiments the guard comprises two discs spaced apart along the length of the guard to form a space between the discs, wherein the space aligns with the blade when engaged with the annular support body.

