GB2325876A

GB2325876A - Ultrasonic cutting device

Info

Publication number: GB2325876A
Application number: GB9811798A
Authority: GB
Inventors: Francis Frederick Hamil Rawson
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-06-05
Filing date: 1998-06-03
Publication date: 1998-12-09
Anticipated expiration: 2018-06-03
Also published as: GB9811798D0; GB9711538D0; GB2325876B

Abstract

An ultrasonic cutting device comprises an annular cutting member 6 having a continuous edge 14 around the periphery thereof. A drive member 10 is provided, comprising bifurcated arms 10a, 10b which may be placed over an outer portion of the cutting member on one side of a diametral line, and secured thereto. In this way vibrations produced by a ultrasonic transducer are transmitted by the drive member 10 to the cutting member 6, the vibrations emanating primarily at the periphery of the cutting member, said vibrations being radially inwardly and outwardly, and also at right angles to the plane containing the cutting member.

Description

PATENTS ACT 1977 WL/A9158GB Title: Improvements Relating to Cutting Devices Descrintion of Invention This invention is concerned with improvements relating to cutting devices, particularly cutting devices which are operative at high (ultrasonic) frequency.

There is disclosed in the specification of my European patent EP 0625086 a cutting device comprising a drive member adapted to provide a source of longitudinal ultrasonic vibrations and a generally annular cutting member having on one side of a diametral plane a driving face to be attached to the source of ultrasonic vibration, a cutting edge extending circumferentially of the cutting member on the other side of the diametral plane. Such a cutting device is hereinafter referred to as being of the kind specified. In the specification of my patent, it is stated that it is preferred that the driving face extends as a cord to the circular configuration of the cutting member, providing a driving face which extends at right angles to the longitudinal axis.

I have determined that in certain circumstances, there are advantages in utilising an alternative construction, and in accordance with this invention there is provided a cutting device of the kind set out above, characterised in that the driving face extends at an angle of other than 90" to the longitudinal axis of the source of vibrations.

Thus for example the driving face may be provided by a ramp or chamfered faces on the cutting member, with the driving member being provided with complimentary faces which may be secured to the cutting member in any convenient way, such as by bolting, welding (including linear friction welding, electron beam welding or laser welding) or bonding, such as diffusion bonding, or involving the use of a foil between the engaging surfaces.

In such a construction, preferably the driving faces extend on opposite sides of a plane containing the annular cutting member, and preferably lie within the range of30" to 600 to said plane containing the cutting member.

Alternatively and preferably, the or each driving face lies in a plane which extends at least substantially parallel to a plane containing the annular cutting member, being provided (e.g.) by an exterior face of the cutting member on each side of said plane.

In this manner, a bifurcated driving member may be placed over a portion of the cutting member, and secured to the driving member, conveniently utilising one ofthe techniques set out above.

According to this invention there is also provided a cutting device of the kind specified wherein the drive member comprises or has secured thereto a bifurcated member which engages or which is adapted to be engaged with the cutting member on opposite sides of a central plane within which the cutting member lies.

Preferably the bifurcated member comprises parallel arms between which the cutting member is engaged or is adapted to be engaged.

The bifurcated member may be engaged with the cutting member in any convenient way, such as bolting, welding (including linear friction welding, electron beam welding or laser welding) or bonding such as diffusion bonding, or involving the use of a foil between the engaging faces.

Preferably the cutting member is provided with a cutting edge extending wholly around the circumference of the cutting member.

In this way, it has been found that the cutting edge of the blade vibrates in a circumferential harmonic mode, with the vibrations in the harmonic mode extending out of the plane containing the cutting member.

There will now be given a detailed description, to be read with reference to the accompanying drawings, of a preferred embodiment of this invention, which has been selected for the purposes of illustrating the invention by way of example.

In the accompanying drawings: figure 1 is a side elevation showing the cutting device which is the preferred embodiment in schematic form; figure 2 is an end elevation of the cutting device shown in figure 1, viewed in the direction of the arrow II of figure 1 and figure 3 is a view showing the application of the invention to a multi-bladed cutting device.

The cutting device which is the preferred embodiment of this invention is generally similar to that described and illustrated in the specification of my European patent EP0625086, to which reference should be made for details of construction and operation not disclosed herein. Reference should be made to said patent specification particularly in relation to the parameters determining the size and shape ofthe various components ofthe cutting device.

The cutting device comprises an annular cutting member 6 having an inner radius of 15mum and an outer radius of 150mm, the cutting member being of any convenient material. I have found that tempered tool steel is particularly suitable, but if desired there may be used a titanium alloy comprising 90% ti, 6% al and 4 parts va, or an aluminium alloy comprising 96% al with 4% cu. Around the periphery of the cutting member a continuous cutting edge 14 is provided. A drive member 10 is provided, comprising bifurcated arms lOL 10b which may be placed over an outer portion of the cutting member, as shown in the drawings, and the arms lOa, lOb are attached to the cutting member, preferably of course to an unreduced portion thereof, by a conventional technique, such as bolting, welding, or bonding.

In use, vibrations produced by an ultrasonic device are transmitted by the drive member 10 to the annular cutting member 6, the vibrations emanating primarily at the periphery of the cutting member, said vibrations being radially inwardly and outwardly, in a pulsating manner, and lying generally within a plane containing the annular cutting member.

Additionally however, it has been determined that by appropriate positioning of the drive member 10 in connection with the cutting member, harmonic vibrations are produced by an interference process which, particularly where the cutting edge extends continuously around the circumference of the cutting member, appear as vibrations of the cutting edge in a plane x-y extending at right angles to the plane A-B containing the cutting member.

It has been found that a combination of the vibration modes in both planes produces a significant improvement in the cutting process.

In figure 3, in which similar numerals have been utilised with the suffix , a multistage cutting device in accordance with this invention is illustrated.

Claims

1 A cutting device of the kind specified wherein the driving face extends at an angle other than at 900 to the longitudinal axis ofthe source of vibration.

2 A cutting device according to claim 1 wherein the driving face is provided by one or more ramps or chamfered faces on the cutting member, and the driving member is provided with one or more complimentary faces secured to the cutting member.

3 A cutting device according to claim 2 wherein the driving faces extend on opposite sides of a plane containing the annular cutting member lying within the range of30" to 600 to the plane containing the cutting member.

4 A cutting device according to claim 1 wherein the or each driving face lies in a plane which extends at least substantially parallel to a plane containing the annular cutting member.

5 A cutting device according to claim 4 wherein the drive member is bifurcated.

6 A cutting device of the kind specified wherein the drive member comprises or has secured thereto a bifurcated member which engages or which is adapted to be engaged with the cutting member on opposite sides of a central plane within which the cutting member lies.

7 A cutting device according to claim 6 wherein the bifurcated member comprises parallel arms between which the cutting member is engaged or is adapted to be engaged.

8 A cutting device according to any of the preceding claims wherein the drive member is interposed between the cutting device and a transducer.

9 A cutting device according to claim 8 wherein the drive member is interposed between the transducer and a plurality of cutting members.

10 A cutting device according to any one of the preceding claims wherein the drive member is secured to the cutting member or cutting members by bolting, welding or bonding.

11 A cutting device constructed and arranged substantially as hereinbefore described with reference (a) to figures 1 and 2, or (b) to figure 3 of the accompanying drawings.

12 Any novel feature or novel combination of features hereinbefore described and/or shown in the accompanying drawings.