GB2320906A

GB2320906A - Ultrasonic cutting machine

Info

Publication number: GB2320906A
Application number: GB9700033A
Authority: GB
Inventors: Barry Edward Vosper Staples
Original assignee: Staples Group Ltd
Current assignee: Staples Group Ltd
Priority date: 1997-01-03
Filing date: 1997-01-03
Publication date: 1998-07-08
Anticipated expiration: 2017-01-03
Also published as: GB9700033D0; GB2320906B

Abstract

An ultrasonic cutting machine 10 comprises a converter 12 arranged to cause a horn 14 to vibrate at a high frequency. A flat lower surface 16 of the horn 14 is brought to bear on a raised rim 18 of an anvil 20. A sheet of material 34 positioned between the flat lower surface 16 of the horn and the raised rim 18 of the anvil will be cut to leave a piece conforming to the shape of the raised rim 18. An ejection system of the ultrasonic cutting machine 10 comprises punches 22 received in openings 26 which extend between the flat lower surface 16 and tuning slots 24 of the horn. When a piece of material has been cut the punches 22 are moved downwardly with respect to the horn to push the cut piece of material out of the anvil 20.

Description

ULTRASONIC CUTTING MACHINES This invention relates to an ultrasonic cutting machine, particularly to an ultrasonic cutting machine having an ejection system, and to a method of ejecting a cut piece of material from an ultrasonic cutting machine.

Known ultrasonic cutting machines typically comprise a horn which is caused to vibrate at ultrasonic frequencies. The vibrating horn is brought to bear on a sheet of material for cutting or welding beneath which is an anvil having a raised lip. Pressure between the raised lip of the anvil and the vibrating horn severs a piece of material from the sheet and seals the cut edges. The sheet of material is drawn through the cutting machine when the horn has been removed from contact with the anvil and the piece of material which has been cut is removed from the surrounding waste material of the sheet.

Disadvantages arise with this type of system because of the undesirably long time it takes to draw the sheet of material through the cutting machine and remove the cut shape. Additionally, the cut piece of material may become partially trapped in the anvil which requires the machine to be stopped and the trapped piece of material to be removed, with consequent disadvantages.

Attempts to overcome the above mentioned disadvantages have included the unsatisfactory approach of intentionally forming an incomplete cut in the material to ensure that the whole sheet of material can be withdrawn from the machine and thereafter severing the remaining part of the incomplete cuts. This results in a low quality cut and also takes an undesirably long time.

The obvious solution was to have an anvil with a hole through its base through which the cut piece could fall.

The problem has been that there was no way an ejection system could be fitted within the horn to propel the cut piece through the hole as the hole has to be smaller than the cut piece owing to the shape of the cutting edge of the anvil. It needs therefore to be pushed through as it will not fall by gravity. A horn must ring like a bell and its shape is very precise and has to be tuned to ring at the right frequency. Any hole large enough to incorporate an ejection system can destroy the ringing of the horn. Due to the ultra high frequency at which a horn vibrates no screw or adhesive material can be attached to its lower face to help incorporate an ejection system, likewise a hole cannot be drilled up the centres of the horn to include an ejection system without destroying the ringing of the horn. This invention takes advantage that transverse slots are often put in the horn to tune it to the right frequency, and this invention takes advantage of those tuning slots to effect an ejection system. The vibrations on the lower face of the horn form patterns and directly under the tuning slots is an area through which a hole can be drilled of roughly equal diameter to the width of the tuning aperture slot. This invention takes advantage of this fact and allows an ejection system to be externally mounted through the tuning slots in the horn and down through the holes of this invention to protrude through the lower face of the horn.

According to a first aspect of the present invention an ultrasonic cutting machine includes a horn having an opening extending through the horn from a first face thereof, and an ejection member received in the opening, wherein the ejection member is movable relative to the horn to protrude from the first face of the horn to eject a cut piece of material from the machine.

The opening may further open into an aperture extending through the horn. The aperture may extend laterally through the horn. The aperture may be a tuning slot.

The ejection member may be received in the opening with substantially no contact between the ejection member and the sides of the opening.

The ejection member may be connected to a cross bar received in the tuning slot, which cross bar may be arranged, in use, to have substantially no contact with the horn.

The horn and cross bar may be made of nonferromagnetic material.

The ejection member may be arranged to move relative to the horn, which movement may be caused by motor means.

The movement may be a reciprocating movement. The movement may be movement between inoperative and operative configurations of the ejection member. In the inoperative configuration an operative end of the ejection member may be received in the opening in the horn. In the operative configuration the operative end of the ejection member may protrude from the first face of the horn. The movement between inoperative and operative configurations may be timed to occur immediately after a cutting operation has been completed by the horn. The movement between inoperative and operative configurations may be timed to occur during a cutting operation.

The ultrasonic cutting machine may include single or multiple ejection members. Each ejection member may have a cross bar attached thereto. The horn may include one or more tuning slots. An opening may open up into each tuning slot.

The ultrasonic machine may include an anvil having an opening therein, through which a cut piece of material may be ejected by the ejection member.

The invention includes a horn for an ultrasonic cutting machine having an opening extending through the horn from a first face thereof and an ejection member movable to protrude from the first face of the horn to eject, in use, a cut piece of material from the machine.

According to a still further aspect of the present invention a method of ejecting a cut piece of material from an ultrasonic cutting machine comprises causing an ejection member to protrude from an opening in a cutting face of a horn of the ultrasonic cutting machine.

The method may include substantially no contact being made between the ejection member and the sides of the opening. The method may include the ejection member moving between inoperative and operative configurations.

In the inoperative configuration an operative end of the ejection member may be received inwardly of the cutting face of the horn. In the operative configuration the operative end of the ejection member may protrude from the cutting face of the horn.

The ejection member may be moved between inoperative and operative configurations whilst the piece of material is being cut. The ejection member may be moved between inoperative and operative positions after the piece of material has been cut.

All of the above aspects may be combined with any of the features disclosed herein, in any combination.

A specific embodiment of the present invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic perspective view of an ultrasonic cutting machine; Figure 2 is a diagrammatic side view of the machine shown in figure 1; and Figure 3 is a diagrammatic partial view of the lower face or working face of the horn of the machine shown in figure 1.

An ultrasonic cutting machine 10 comprises a converter 12 arranged to cause a horn 14 to vibrate at a high frequency. A flat lower surface 16 of the horn 14 is brought to bear on a raised rim 18 of an anvil 20. A sheet of material 34 (see figure 2) positioned between the flat lower surface 16 of the horn and the raised rim 18 of the anvil 20 will be cut to leave a piece conforming to the shape of the raised rim 18. An ejection system of the ultrasonic cutting machine 10 comprises punches 22 received in openings 26 which extend between the flat lower surface 16 and tuning slots 24 of the horn. When a piece of material has been cut the punches 22 are moved downwardly with respect to the horn to push the cut piece of material out of the anvil 20.

The ultrasonic cutting machine 10 will now be described in greater detail.

The horn 14 is caused to vibrate at a frequency of approximately 20 kHz by the converter 12. The horn 14 is made from a material which can withstand such high frequencies. Typically this material may be titanium or an alloy including steel.

The precise shape of the horn 14 is critical to the correct functioning of the cutting machine 10. If the shape and finish of the horn 14 is incorrect then it will not ring correctly and hence its function will be severely impaired. The flat base 16 of the horn 14 must have a flatness formed to an extremely fine tolerance.

The tuning slots 24 are precisely located in order to enable the correct functioning of the cutting machine 10.

The tuning slots 24 pass completely through the horn 14.

The two apertures 26, one of which extends from the base of each tuning slot 24 through to the base 16 of the horn 14, have a diameter of 10mum, which corresponds to the width of the tuning slots 24.

Each opening 26 receives one of the punches 22 each of which has a length slightly longer than the distance between the base of the tuning slot 24 and the bottom base 16 so that one end of the punch protrudes into the tuning slot when the other end is located inward of the flat base 16. The diameter of each punch 22 is chosen so that it is clear from the sides of the opening. However, a small amount of contact between punch 22 and horn 14 can be tolerated without a significant impairment of the efficiency of the machine.

The top of each punch 22 has connected thereto a horizontal bar 28. Each bar 28 is arranged to be moved up and down by means of a vertical bar 30, which is moved by motor means (not shown). The sense of movement is shown by the arrows A in figures 1 and 2. At all times during its upward and downward movement the horizontal bar 28 does not contact the horn 14. The punches 22 and the bars 28 and 30 are made of a non ferrous material in this example, in order to minimise the undesirable heating effect caused by the ultrasonic vibration.

The anvil 20 has a central cavity 32 inward of the raised rim 18. The cavity 32 allows a piece of material which has been cut to drop out of the anvil 20. The raised rim 18 of the anvil 20 must be machined to have a flatness of corresponding accuracy to that of the lower face 16 of the horn 14. This is to ensure both the maximum amount of contact between the lower face 16 and the rim 18 and to ensure minimum disturbance of the acoustic characteristics of the horn 14.

The cutting machine 10 has lowering means (not shown) by which the horn 14 can be lowered on to the raised rim 18 of the anvil 20 to perform a cutting operation. The horn 14 can be raised by the same means. The sense of movement is shown by the arrows B in figures 1 and 2. The motor means for the punches 22 moves with the horn 14, but is arranged so that the punches 22 can be moved relative to the horn 14.

The operation of the ultrasonic cutting machine 10 will now be described.

A sheet of material 34 (see figure 2) from which a shape corresponding to the shape of the raised rim 18 of the anvil 20 is to be cut is fed between the anvil and the horn. The material 34 in this example is used for bra pads, but it will be understood that any of the materials which can be cut with an ultrasonic cutting machine could be used to equally good effect. The material 34 comprises facing material on either side and a section of foam padding therebetween. The material 34 is fed into the ultrasonic cutting machine 10 in the direction shown by the horizontal arrow C in figure 2. When the piece of material is in position the horn 14 is lowered on to the material 34 to sandwich the material between the lower face 16 of the horn 14 and the raised rim 18 of the anvil 20. At the same time the horn is caused to vibrate at an ultrasonic frequency by the converter 12 to thereby cut the material along the line of contact between the horn 14 and the anvil 20 formed by the raised rim 18 of the anvil 20, and seal the cut edges, thus enclosing the foam within the facing material.

When the ultrasonic vibration has been given sufficient time to cut and seal the piece of material 34 the punches 22 are moved downwardly through the openings 26 in the horn 14 to thereby protrude from the lower face 16 of the horn 14 and push the piece of material which has been cut down through the opening 32 in the anvil 20. The punches 22 are then retracted into their openings 26 and the horn 14 is raised. The waste material from which the chosen shape has been cut is then drawn through the cutting machine until an un-cut section of material 34 overlies the anvil 20. The lowering and vibration of the horn 14 can then be repeated followed by the ejection movement of the punches 22. A cycle of cutting, ejecting and moving the material 34 through the cutting machine 10 can be completed in approximately 1 second.

Significant advantages are evident over previous ultrasonic cutting machines, in which the cut piece of material had to be removed manually after the material had been withdrawn from the machine. Previous machines, as mentioned above, frequently suffered from a piece of cut material jamming in the anvil requiring long periods of undesirable down time of a cutting machine. In order to overcome the above disadvantages the unsatisfactory operation of producing an imperfect cut which would have to be severed later was used. These disadvantages are not present in the cutting machine described above.

The significant advantage of a cutting cycle being completed three times more quickly than previous systems is also obtained from the cutting machine described above.

The surprising effect that drilling holes from the base of the horn to the tuning slots has no appreciable negative effect on the functioning of an ultrasonic cutting machine has been used to provide the significant advantages mentioned above.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. An ultrasonic cutting machine includes a horn having an opening extending through the horn from the first face thereof, and an ejection member received in the opening, wherein the ejection member is movable relative to the horn to protrude from the first face of the horn to eject a cut piece of material from the machine.

2. An ultrasonic cutting machine as claimed in claim 1, in which the opening further opens into an aperture extending through the horn.

3. An ultrasonic cutting machine as claimed in claim 2, in which the aperture extends laterally through the horn.

4. An ultrasonic cutting machine as claimed in claim 3, in which the aperture is a tuning slot.

5. An ultrasonic cutting machine as claimed in claim 4, in which the ejection member is connected to a cross bar received in the tuning slot.

6. An ultrasonic cutting machine as claimed in claim 5, in which the cross bar is arranged, in use, to have substantially no contact with the horn.

7. An ultrasonic cutting machine as claimed in either claim 5 or claim 6, in which the horn and cross bar are made of non-ferromagnetic material.

8. An ultrasonic cutting machine as claimed in any preceding claim, in which the ejection member is received in the opening with substantially no contact between the ejection member and the sides of the opening.

9. An ultrasonic cutting machine as claimed in any preceding claim, in which the ejection member is arranged to move relative to the horn.

10. An ultrasonic cutting machine as claimed in claim 9, in which the movement is a reciprocating movement.

11. An ultrasonic cutting machine as claimed in either claim 9 or claim 10, in which the movement is a movement between inoperative and operative configurations of the ejection member.

12. An ultrasonic cutting machine as claimed in claim 11, in which in the inoperative configuration an operative end of the ejection member is received in the opening in the horn.

13. An ultrasonic cutting machine as claimed in either claim 11 or claim 12, in which in the operative configuration the operative end of the ejection member protrudes from the first face of the horn.

14. An ultrasonic cutting machine as claimed in any one of claims 11 to 13, in which the movement between inoperative and operative configurations is timed to occur immediately after a cutting operation has been completed by the horn.

15. An ultrasonic cutting machine as claimed in any one of claims 11 to 13, in which the movement between inoperative and operative configurations is timed to occur during a cutting operation.

16. An ultrasonic cutting machine as claimed in any preceding claim which includes single or multiple ejection members.

17. An ultrasonic cutting machine as claimed in claim 16, in which each ejection member has a cross bar attached thereto.

18. An ultrasonic cutting machine as claimed in either claim 16 or claim 17, in which the horn includes one or more tuning slots.

19. An ultrasonic cutting machine as claimed in claim 18, in which an opening opens up into each tuning slot.

20. An ultrasonic cutting machine as claimed in any preceding claim which includes an anvil having an opening therein, through which a cut piece of material may be ejected by the ejection member.

21. A horn for an ultrasonic cutting machine has an opening extending through the horn from a first face thereof and an ejection member movable to protrude from the first face of the horn to eject, in use, a cut piece of material from the machine.

22. A method of ejecting a cut piece of material from an ultrasonic cutting machine comprises causing an ejection member to protrude from an opening in a cutting face of a horn of the ultrasonic cutting machine.

23. A method of ejecting a cut piece of material as claimed in claim 22 which includes substantially no contact being made between the ejection member and the sides of the opening.

24. A method of ejecting a cut piece of material as claimed in claim 22 or claim 23 which includes the ejection member moving between inoperative and operative configurations, in which in the inoperative configuration an operative end of the ejection member is received inwardly of the cutting face of the horn and in the inoperative configuration the operative end of the ejection member protrudes from the cutting face of the horn.

25. A method of ejecting a cut piece of material as claimed in claim 24, in which the ejection member is moved between inoperative and operative configurations whilst the piece of material is being cut.

26. A method of ejecting a cut piece of material as claimed in claim 24, in which the ejection member is moved between inoperative and operative positions after the piece of material has been cut.

27. An ultrasonic cutting machine substantially as hereinbefore described, with reference to the accompanying drawings.

28. A method of ejecting a cut piece of material from an ultrasonic cutting machine substantially as hereinbefore described with reference to the accompanying drawings.