GB2255035A - Ultrasonic device - Google Patents

Abstract

A transmitting member for an ultrasonic device comprises a plurality of parts secured together by (e,g,) welding or bonding along a line or lines extending parallel to the longitudinal axis of vibration, and/or along a line extending other than parallel to the longitudinal axis of vibration. In one embodiment (not shown) three sections 22a, 22b, 22c of the transmitting member are secured together by adjacent flats 24a1, 24b1, 24a2, 24b2 by a linear friction welding operation. In a second embodiment, four components 40a, 40b, 40c and 40d are secured together by electron beam welding along transverse weld lines W5. In a fourth embodiment (not shown) four working components 62a, 62b, 62c and 62d are secured at anti-nodic regions, the working components extending at right angles to the longitudinal axis of the body 60, to provide four working faces, Z1, Z2, Z3, Z4. <IMAGE>

Description

Title: "Improvements relating to ultrasonic devices" Description of Invention This invention is concerned with ultrasonic devices, particularly of the kind particularly of the kind (hereinafter referred to as being of the kind specified) comprising a transducer driven by a high power generator adapted to provide a source of high frequency mechanical vibrational energy, and a transmitting member (conventionally termed a "horn") secured either directly or indirectly to the transducer and which is adapted to transmit vibrational energy to a workpiece.

Typically the vibrational energy is applied to the workpiece to effect a cutting operation (which may be a part-severing of the workpiece), a welding operation or a heat sealing action.

The transducer may be, for example a piezoelectric or magnetostrictive device, and the transmitting member may transmit the vibrational energy from an operative face to the workpiece, either directly, or through a tip or tool secured to the transmitting member at said end face.

If desired a booster may be interposed between the transducer and the transmitting member, to produce a desired amplitude of vibration of the transmitting member at the operative face thereof.

Conventionally the transmitting member has an axial length equal to N)22, where N is an integer and )i is the wavelength of vibration, such that the ends of the transmitting member afford anti-nodes, vibrating at the full amplitude of the vibration, there being at least one node along the length of the transmitting member.

Conventionally the transmitting member is manufactured (preferably of titanium or aluminium alloy, such as duraluminium, but which may be of other materials, such as stainless steel) in one piece, and this can be expensive, and seriously limits the design of transmitting member which can be used.

According to this invention there is provided a transmitting member for an ultrasonic device which is prefabricated from one or more parts secured together.

Preferably the parts are secured together over extensive surfaces, such as by welding, or bonding. Particularly suitable for use is linear friction welding, electron beam welding, laser welding or diffusion bonding, involving the heating of surfaces to be bonded to a temperature slightly below the melt temperature of the material, and pressing the parts together under high pressure, optionally a foil of a suitable material such as copper or silver being provided between the contacting surfaces.

The parts may be joined together on a line or lines extending parallel to the longitudinal axis of vibration, and it has been found, surprisingly, that by this way a transmitting member may be produced which is viable - that is the member maintains its integrity over extensive periods of use, despite the fact that the join extends other than over an area which is substantially nodic, and/or of varying amplitude.

In this manner a transmitting member having a relatively complicated construction may be produced, having a plurality of operative faces, or a single operative face arranged in a complication array.

Alternatively of in addition, the parts may be joined together along a line or lines extending other than parallel to the longitudinal axis, such as along a line extending transverse to the longitudinal axis, and again it has been found (surprisingly) that by this method a transmitting member may be produced which is viable.

There will now be given detailed descriptions, to be read with reference to the accompanying drawings, of a number of transmitting members which have been selected for the purposes of illustrating the diversity of cutting member which may be produced utilising the present invention.

In the accompanying drawings: FIGURE 1 is a schematic view illustrating a conventional ultrasonic device, being of the kind specified; FIGURES 2 and 3 illustrate a transmitting member which is a first embodiment of the invention; FIGURE 4 illustrates a transmitting member which is a second embodiment of the invention; FIGURE 5 illustrates a transmitting member which is a third embodiment of the invention; FIGURE 6 Illustrates a modified construction of the third embodiment; FIGURE 7 illustrates a transmitting member which is a fourth embodiment of the invention; FIGURE 8 illustrates a transmitting member which is a fifth embodiment of the invention; and FIGURE 9 illustrates a transmitting member is a sixth embodiment of the invention.

The conventional ultrasonic device, illustrating in Figure 1, comprises a transducer 6 comprising a piezoelectric device, a booster 8 provided with flanges 10, and a transmitting element or horn 12 secured to the end face 7 of the booster 8, the horn conventionally comprising an operative end face 14, at which a tool may if needed be provided.

The booster 8 and the transmitting member 12 each have a length equivalent to No/2, where 2 is the wavelength of vibration, and N is an integer, whereby vibrations produced at the front end 7 of the generator 6 are transmitted as compression/tension forces on the input face 13 to the transmitting member 12.

Along the length, in the axial direction, of both the booster 8 and the transmitting member 12, one or more nodes (regions of no displacement in the axial direction) may be provided, dependant upon the length of the component and the wavelength. Thus, at a central region of the booster 8, at a nodic point thereof, flanges 10 may be provided to enable the device to be secured in position.

Figure 2 illustrates a transmitting member which is the first embodiment of the invention, in the form of a multi-stage horn providing a plurality of operative faces 20, each of which may be utilised to perform an ultrasonic tooling operation, which may be welding, or cutting.

In the first embodiment three component horn sections 22a. 22h, 22 are provided, which have a generally cylindrical body section, and which are secured together by adjacent flats 24#, 24#1, 24ffi2, 24b2 by a linear friction welding operation, the line of weld extending a substantial axial distance L and a smaller transverse distance M, between adjacent pairs of the three components.

Additional flats 26, 26 are provided on the two outer bodies, enabling a strap to be utilised to further secure the three horn parts together, e.g.

whilst they are being bonded or welded together. In this embodiment, the central body 22b alone is secured, by way of booster 30, to a power transducer 32, conveniently by the use of a threaded element 44, although other means may be utilised to secure the horn to the booster, if desired.

In this manner by the use of a single generator and booster, three outputs may be provided to work in synchronism.

In the second embodiment, illustrated in Figure 4, a transmitting member is provided comprising four components parts secured together in the axial direction, to provide a cruciform-shaped operative end 42, shown in the embodiment in the form of a cutting arrangement. In this second embodiment, the transmitting member may be secured to a booster, or to a power generator directly, by the use of a screw hole 44.

In the second embodiment, the four components 40, 40h 40k, 406 and 4051.

are conveniently secured together by electron beam welding, although other welding techniques may be used.

As shown in Figure 4, the components are secured together along longitudinal welding lines W1-W4, but if desired each of the components may itself be produced from component parts, which may be secured together along transverse weld lines W5.

It will be appreciated that this technique may be utilised to produce a transmitting member having fewer than, or more than four longitudinal components.

The third embodiment illustrated in Figure 5 shows the fabrication of an otherwise conventional horn 50, manufactured from titanium by three components parts 52ss, 52h 52g, 5# secured together by linear friction welding, over areas indicated A and B. In this manner the transmitting member may be manufactured from individual parts which may be produced less expensively than the machining of the transmitting member from a one piece bar stock of titanium.

An alternative version is shown in Figure 6, in which similar numerials with an apostrophe ['] are used, comprising a welding tip 5#1.

In the fourth embodiment of the invention, illustrated in Figure 7, a transmitting member 58 is illustrated, comprising an elongate body 60, provided at one end thereof with a screw hole 61 to enable the body to be secured to a transducer, through the intermediary if desired of a booster.

Secured to the body 60 over weld areas A, B, C and D are four working components 62# 62X 62 and 62d which are secured at anti-nodic regions, preferably the regions of maximum vibrational displacement, the working components extending at right angles to the longitudinal axis of the body 60, and providing four working faces, Z1, 22, Z3, Z4 lying in planes extending in the longitudinal direction of the transmitting member.

Conveniently the working components 62# to 62d may be secured to the body by diffusion bonding, although the welding techniques may be used, as described above.

Additionally the body itself is provided with an end working face Z5, extending at right angles to the longitudinal axis of the transmitting member 58.

Alternative to the provision of working faces Z1 to Z4 as shown, this constructional technique could be utilised to provide working faces in the form of cutting elements adapted to provide travelling cuts as the transmitting member 58 is vibrated and the working elements are moved relative to the workpiece in a direction at right angles to the longitudinal axis of the horn, In the fifth embodiment illustrated in Figure 8, a body 70 is provided, having a threaded aperture 72 for connection to a transducer, and to which on the opposite side, for component parts 74L 74h 74 and 74d are secured, such as by diffusion bonding, to provide four working faces 75a, 7soh, 75c and 754 adapted to operate in synchronism, the component parts 74 may themselves be produced in two pieces secured together over areas A1-A4, the four component parts being secured to the body 70 over an area B.

In the sixth embodiment illustrated in Figure 8, a composite horn is illustrated comprising a body 80, provided with a threaded attachment aperture 82a, which is welded to a nodal mounting flange 84, allowing the horn to be secured in desired position in relation to other parts of an apparatus, a tool part 86 being secured to the opposite side of the mounting flange 84, similarly conveniently by welding, providing a working face 88.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in the terms or means for performing the desired function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (11)

1. A transmitting member for an ultrasonic device, which is prefabricated from one or more parts secured together.

2. A transmitting member according to Claim 1 wherein said parts are secured together over extensive surfaces.

3. A transmitting member according to one of Claims 1 and 2 wherein said parts are secured together by welding.

4. A transmitting member according to Claim 3 wherein said parts are secured together by linear friction welding, electron beam welding or laser welding.

5. A transmitting member according to one of Claims 1 and 2 wherein said parts are secured together by bonding.

6. A transmitting member according to Claim 5 wherein said parts are secured together by diffusion bonding.

7. A transmitting member according to Claim 6 involving the use of a foil between the connecting surfaces.

8. A transmitting member according to any one of the preceding claims wherein said parts are joined together on a line or lines extending parallel to the longitudinal axis of vibration.

9. A transmitting member according to any one of the preceding claims wherein said parts are joined together along a line or lines extending other than parallel to the longitudinal axis of vibration.

10. A transmitting member for an ultrasonic device, constructed and arranged substantially as hereinbefore described with reference (a) to Figures 2 and 3; (b) to Figure 4; (c) to Figure 5; (d) to Figure 6; (e) to Figure 7; (f) to Figure 8; or (g) Figure 9 of the accompanying drawings.

11. Any novel feature or novel combination of features as herein before described and/or as shown in the accompanying drawings.