GB2313083A - Ultrasonic device - Google Patents

Abstract

An ultrasonic device comprises a source 12 of ultrasonic vibrations having an operative face 14 and at least one tool (16 fig 2) having an operative edge 20. Securing means 24 are provided to secure the tool 16 to the source 12, the securing means comprises an elongate threaded member 24 which may be threadedly secured to both the tool 16 and the source 12. The two ends 24a, 24b of the threaded member are oppositely threaded. Rotation of "spanner flats" 25 on the threaded member adjusts the separation between tool and source. When at the desired separation the threaded member is locked to the tool and source by means of nuts 28a, 28b. This adjustment enables the tool to be tuned to the correct frequency.

Description

Title: Improvements relating to ultrasonic devices Description of Invention This invention is concerned with improvements relating to ultrasonic devices, comprising a source of ultrasonic vibrations, and a tool having an operative edge which in use is vibrated at high frequency.

A conventional ultrasonic device comprises, as source of ultrasonic vibrations, an electrically operated transducer producing on an operative face thereof (which may be provided by a booster attached to the transducer) high frequency vibrations, and a tool secured to the transducer, such that the distance between the operative face and the operative edge of the tool equals n A /2, when n is an integer and A is the wave length of the vibrations. In this way ultrasonic vibrations occurring at the operative face of the transducer cause the operative edge to vibrate in synchronism.

Conventionally the tool may be elongate, and may be secured to the operative face such as by welding, or more conventionally by the use of screwthreaded means.

An example of an ultrasonic device of the kind described above is set out in the Specification of my co-pending Application EP0625086-A to which reference may be made for details of construction and operation not included herein.

Difficulty is encountered in the assembly or adjustment of ultrasonic devices of the kind set out above, for example where the tool is a cutting tool, particularly where it is desired to utilise a plurality of tools in close proximity and/or where the tools are extensive at least in a plane which extends parallel to the axis of the vibrations, and it is one of the various objects of this invention to reduce some at least of these problems.

According to this invention there is provided an ultrasonic device comprising a source of ultrasonic vibrations having an operative face, at least one tool having an operative edge, and securing means to secure the tool to the source, said securing means comprising an elongate threaded member which may be threadedly secured to both the tool and the source.

Most conveniently, the securing means is connected directly to the tool, but alternatively the securing means may be connected between the source and an intermediate member, to which the tool is connected. Such a connecting member may comprise a responsive face, which is connected directly to the operative face of the source, and itself provides an operative face to which the tool is connected.

In particular, the intermediate member may provide the facility for the changing of the direction of the longitudinal axis of the vibrations, having (eg) an operative face which extends at right angles to the responsive face, and/or provide for the spliting of the longitudinal vibrations into two sets, to provide for cutting onto spaced longitudinal axes.

For convenience the term "tool" is used hereinafter to include both the tool per se, and any intermediate member which may be interposed between the source and the tool per se, and the claims which are appended to this application are where appropriate to be interpreted as including within the scope of protection provided, a construction in which the elongate threaded member is threadedly secured to the tool indirectly.

Preferably the securing means is operative to secure the tool to the source in a manner whereby the distance between the operative face and the operative edge is no/2, where n is an integer, and A is the wave length of vibrations of the source.

Conveniently the threaded member comprises opposite portions which are oppositely threaded, so that by rotation of the threaded member one end portion may be threadedly engaged with the source, and the opposite end portion threadedly engaged with the tool, conveniently being so received in threaded bores provided in the source and tool respectively.

Preferably the securing means comprises a clamping member to clamp the threaded member firmly against the operative face of the source, conveniently in the form of a nut threadedly received on the threaded member, and optionally a clamping device for clamping the threaded member at the opposite end portion against the tool.

The invention above described is particularly suitable for use in relation to an ultrasonic device having a plurality of tools arranged in relatively close proximity, and is particularly appropriate for use in relation to an ultrasonic cutting device, comprising a plurality of blades arranged in close proximity to (for example) cut an article being processed (such as a loaf of bread) in to slices.

Difficulty is also encountered in adjusting the separation of the operative face and the operative edge, in accordance with small variations of the frequency of vibration of the transducer from (eg) the prescribed frequency, and it is thus another of the various objects of this invention to provide a method of operating an ultrasonic device, in which tuning of the device may be carried out relatively easily.

Thus according to this invention there is also provided a method of operating an ultrasonic device of the kind comprising a source of ultrasonic vibrations having an operative face, at least one tool having an operative edge, and securing means to secure the tool to the source, said securing means comprising an elongate threaded member which may be threadedly secured to both the tool and the source, involving the step of rotating the elongate threaded member relative to the tool and/or source to tune the tool to the frequency of the source.

This aspect of the invention is particularly advantageous in relation to ultrasonic devices comprising a plurality of tools arranged in relatively close proximity, where such adjustment as may be desirable for tuning purposes will be difficult to accomplish.

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

In the accompanying drawings: Fig 1 is a perspective view of the device which is the preferred embodiment of the invention; Fig 2 is a side elevation thereof; Fig 3 is an underneath plan view; Fig 4 is a view corresponding to Fig 3 showing cutting elements of the device having been adjusted.

The ultrasonic device which is the preferred embodiment of this invention is specifically an ultrasonic cutting tool, comprising a source of vibrations, afforded by a mother horn 12, having an operative face 14 which vibrates at a predetermined frequency.

Secured to the face 14 are a plurality of cutting tools 16, in the form of annular cutting discs 18 having cutting edges 20, as is described in the European Patent Specification mentioned above, each cutting device 20 comprising on a peripheral edge a flat attachment surface 22 which is provided with a threaded bore 23 which is aligned with the centre of the cutting disc 18.

The tool 16 is attached to the horn 20 by the use of a securing device in the form of a spindle 24, said securing device having opposite ends 24L 24which are oppositely threaded. The portion 24a may be threadedly inserted into a receiving aperture 26 extending through the face 14, whilst the portion 24b may be threadedly received in the threaded bore 23.

Thus by locating the tool 16 relative to the horn 12 the securing device may, be threadedly attached to both the horn 12 and the tool 16 by rotation of the spindle 24 in one direction, conveniently assisted by the provision of "spanner flats" 25 at a central region of the spindle.

At least one nut 28a is provided, conveniently on the portion 24a of the spindle, such that when the tool has been attached to the horn 12 in a desired position, particularly such that the distance between the face 14 and the centre of the cutting disc 18 equals nA/2 the nut 28 may be tightened to lock the spindle in position.

In this manner a plurality of tools 16 may be secured to the horn 12 in a convenient manner, which may not otherwise be possible in circumstances where, as in the preferred embodiment, the tool extends a significant distance in a direction at right angles to the longitudinal axis, whereby rotation would be prevented by the presence of an adjacent tool.

In this manner a plurality of tools may be mounted on a single horn 12 such that their operative faces (cutting edges 20) are closely proximate, enabling a working operation to be carried out at several points closely adjacent to a work piece.

For example in the cutting of a work piece in to slices, such as in the provision of sliced bread, a loaf of bread may be moved through the cutting tools 16 so as to produce cuts which are appropriate to the desired thickness of slice, allowing ultrasonics to be used in cutting bread which heretofore has been difficult to accomplish without undue wastage of material.

Similarly, other articles may be cut or sliced relatively easily. Additionally where the tools 16 are other than cutting tools (such as welding tools) welds may be provided on a workpiece along closely spaced lines.

Additionally, by the use of this invention the tools may be secured to a horn in a manner in which tuning of the device may be carried out relatively easily, by rotation of the spindle 24 to adjust the distance between the face 14 and the edge 20, so that the tool 18 is tuned to the actual frequency of the horn 20.

An additional advantage of the use of this method of securing the tools to a mother horn is that the effective spacing between the operative edges of the tools may be varied by rotation of the tools about the longitudinal axis. As is shown in figure 3, the effective spacing between the discs may be maximised by arranging for the discs 18 to extend at right angles to a plane containing the bores 26, or may be reduced by arranging that the cutting discs lie in parallel planes extending at an acute angle to said axis. As is shown in figure 3, in this way the spacing of the cuts may be selected relatively easily.

Conveniently linking means 32 , 32b may be provided to ensure that the cutting disc 18 remain in parallel relationship, and may if desired be connected to operating mechanism automatically to cause the discs 18 to rotate about the axis of the spindle, whereby the spacing between adjacent discs may readily be changed.

Claims (14)

1. An ultrasonic device comprising a source of ultrasonic vibrations having an operative face, at least one tool having an operative edge, and securing means to secure the tool to the source, said securing means comprising an elongate threaded member which may be threadedly secured to both the tool and the source.

2. An ultrasonic device according to claim 1 wherein the securing means is operative to secure the tool to the source in a manner whereby the distance between the operative face and the operative edge is n A/2, where n is an integer, and A is the wavelength of vibrations of the source.

3. An ultrasonic device according to claim 1 or 2 wherein the threaded member comprises opposite portions which are oppositely threaded, so that by rotation of the threaded member one end portion may be threadedly engaged with the source, and the opposite end portion threadedly engaged with the tool.

4. An ultrasonic device according to claim 3 wherein the threaded member is received in threaded bores provided in the source and tool respectively.

5. An ultrasonic device according to any one of the preceding claims wherein the securing means comprises a clamping member to clamp the threaded member firmly against the operative face of the source.

6. An ultrasonic device according to claim 5 wherein the clamping member comprises a nut threadedly received on the threaded member.

7. An ultrasonic device according to claim 5 or 6 wherein the securing means further comprises a clamping device for clamping the threaded member at the opposite end portion against the tool.

8. An ultrasonic device according to any one of the preceding claims wherein it comprises a plurality of tools arranged in relatively close proximity.

9. An ultrasonic device according to claim 8 wherein the plurality of tools comprises a plurality of blades for cutting.

10. A method of operating an ultrasonic device according to any one of the preceding claims, involving the step of rotating the elongate threaded member relative to the tool and/or source to tune the tool to the frequency of the source.

11. The invention according to any one of the preceding claims in which the securing means extends between the source of ultrasonic vibrations and an intermediate member to which the tool is secured.

12. An ultrasonic device substantially as hereinbefore described with reference to the accompanying drawings.

13. A method of operating an ultrasonic device, to tune the tool to the frequency of the source, both carried out substantially as hereinbefore described with reference to the accompanying drawings.

14. Any novel feature or novel combination of features as herein defined and/or shown in the accompanying drawings.