GB2167707A

GB2167707A - Ultrasonic cutting and sealing

Info

Publication number: GB2167707A
Application number: GB08516348A
Authority: GB
Inventors: Gary N Flood; Carmine M Mango
Original assignee: Branson Ultrasonics Corp
Current assignee: Branson Ultrasonics Corp
Priority date: 1984-12-03
Filing date: 1985-06-28
Publication date: 1986-06-04
Also published as: FR2574017B1; GB8516348D0; DE3525400A1; IT8548867A0; FR2574017A1; GB2167707B; IT1183033B

Abstract

An ultrasonic seal and cut method and apparatus comprises an ultrasonic sealing and cutting station which includes a horn adapted to be resonant at an ultrasonic frequency and an oppositely disposed anvil having a sealing surface and a cutting surface. As sheet material is passed through the station, the sheet material is cut and sealed in a marginal region adjacent to the cut. A substantially thermoplastic filament, either monofilament or multifilament, is fed together with the sheet material through the station in a position to cause the filament to fuse with the material in the marginal region. The addition of the filament permits the ultrasonic seal and cut method to be used for sheet material having a relatively low thermoplastic fiber content, exhibiting an open mesh weave, or being made from natural fibers. <IMAGE>

Description

SPECIFICATION Ultrasonic sealing and cutting method and apparatus This invention refers to an ultrasonic seal and cut method and apparatus and, more specifically, refers to an ultrasonic seal and cut method and apparatus for textile sheet material which is fed in a continuous manner through a seal and cut station for providing simultaneously a cut and sealed edge on the material to prevent the unraveling of threads or the existence of a frayed edge.

The use of ultrasonic energy for simultaneously sealing and cutting the edge of plastic and textile material is well known in the prior art. The patents listed hereafter are illustrative of such prior art: Balamuth U.S. Pat. No. 3,254,402 June 7, 1966 Deans U.S. PaT. No. 3,308,003 March 7, 1967 Sulzer Swiss Pat. No. 439,158 June 30, 1967 Obeda U.S. Pat. No. 3,378,429 April 16, 1968 Sager U.S. Pat. No. 3,657,033 April 18, 1972 Reifenhauser U.S. Pat. No. 3,681,176 August 1, 1972 Obeda U.S. Pat. No. 3,697,357 October 10,1972 Obeda U.S. Pat. No. 3,737,361 June 5, 1973 Ries German GM 7401580 May 2, 1974 Parry U.S. Pat. No. 3,852,144 December 3, 1974 Calemard U.S. Pat.No. 4,097,327 June 27, 1978 The principal advantage of the ultrasonic seal and cut method is that the edge of the textile material, while being cut, simultaneously is sealed by the dissipation of ultrasonic energy, thereby preventing the presence of a frayed edge or the unraveling of threads on such material.

In order to successfully apply the ultrasonic method to textile materials, it is necessary that the textile material contains a significant amount of thermoplastic fibers, typically 50 percent or more. The thermoplastic material, under the influence of ultrasonic energy, softens and flows and subsequently rigidifies when no longer subjected to ultrasonic energy, thus leaving a fused surface in a narrow marginal region adjacent to the cut.

As stated heretofore, the above described method is not used successfully when the thermoplastic fiber content falls below the required amount or when the sheet material is a relatively open weave. The present invention discloses the use of a thread or filament, preferably a thermoplastic material, which is fed together with the sheet material through the ultrasonic seal and cut station to cause the filament to melt and become fused with the sheet material in the marginal region adjacent to the cut.In this manner, the sheet material, if a loose weave, is reinforced at the edge to thereby provide a significantly improved edge which is characterized by better wear and tear resistance, and in cases where the material contains less than the required content of thermoplastic fibers or contains primarily natural fibers, such as cotton fibers, the addition of the thermoplastic filament increases the thermoplastic content at the edge to a degree that a sealed edge is achieved.

The present invention provides the method of providing a finished edge on sheet material utilising an ultrasonic seal and cut apparatus comprising the steps of: providing an ultrasonic seal and cut station comprising an anvil and an opposing horn adapted to be resonant at an ultrasonic frequency; passing sheet material through said station for causing material disposed between said anvil and said horn to be cut and simultaneously sealed in a marginal region adjacent said cut in response to said horn being resonant and in contact with the sheet material passing over said anvil;; feeding at least one filament adapted to melt responsive to the dissipation of ultrasonic energy provided by said horn simultaneously with the sheet material between said anvil and said horn in a position for causing said filament to melt and become fused with the sheet material in said marginal region, and removing the sealed and cut portion of sheet material from the seal and cut station.

The present invention also provides an ultrasonic seal and cut apparatus for sheet material comprising a seal and cut station in the form of an anvil and an opposing horn adapted to be resonant at an ultrasonic frequency for providing at its output surface ultra sonic energy to the sheet materail fed over said anvil, means for feeding sheet material through said station; said anvil having a cutting surface and an adjacent sealing surface; means for feeding a filament, adapted to melt responsive to the dissipation of ultra sonic energy provided by said horn, simultaneously with the sheet material between said anvil and said horn, whereby to cause said cutting surface to cut the sheet material responsive to said horn being resonant and in contact with the sheet material and said filament to melt and become fused with the sheet material in a marginal region adjacent the cut and defined by said sealing surface.

As will become apparent from the description hereafter, the filament, preferably a thermoplastic material, may either be a monofilament or a multifilament, and may be either of the same color as the sheet material or may be of different color than the sheet material for providing, in the latter instance, a decorative appearance.

The advantage of adding a relatively thin filament resides in the fact that the thread flows into the interstices of the sheet material and thus does not add to the thickness of the base sheet material as is the case, for instance, in the Swiss patent supra, where a wide binding tape is used to cover the cut thread ends.

In addition, the preferred method is particularly suited for providing a finished edge on non-woven sheet material where the fibers are randomly oriented. The method is applicable also to woven material made on shuttleless looms where a non-finished edge is obtained and such edge must be trimmed and finished before the sheet material is ready for sale.

Moreover, the method concerns an improvement in feeding the filament to the area underneath the ultrasonic horn for contact with the textile material.The filament is relatively thin, yet must be positioned most accurately in the area underneath the ultrasonic horn which is opposed by an anvil having the sealing and cutting surfaces. In a preferred embodiment of the invention, the horn is provided with a groove or an inclined bore at the output end of the ultrasonic horn, the grove or bore extending angularly from the side of the horn to a terminus at the horn underside which forms the output surface contacting the sheet material to be cut and sealed. The bore is dimensioned to guide the filament material and to assure that the filament at all times remains disposed accurately in relation to the cut and sealing surfaces of the anvil.

Further features of the present invention will become more clearly apparent by reference to the following description when taken in conjunction with the accompanying drawings.

Brief description of the drawings Figure 1 is a schematic illustration of a typical ultrasonic seal and cut apparatus; Figure 2 is an elevational view of a typical ultrasonic seal and cut station; Figure 3 is a schematic illustration of textile material having an ultrasonically sealed marginal region adjacent to the cut in accordance with the present invention; Figure 4 is an illustration showing the sealing and cutting of textile material, which material is disposed between an ultrasonic horn and an anvil; Figure 5 is an illustration showing an arrangement of the textile material and the filament disposed between an ultrasonic horn and an anvil prior to sealing and cutting; Figure 6 is a view similar to Figure 5, but showing an alternative arrangement;; Figure 7 is an illustration similar to Figure 5 wherein two filaments are used as may be needed in the case of an ultrasonic slitting apparatus; Figure 8 depicts another embodiment wherein the filament is guided by a groove in the ultrasonic horn; Figure 9 is a view along line 9-9 in Figure 8; Figure 10 depicts another alternative embodiment of the present method and apparatus, and Figure 11 is a schematic view of a further alternative embodiment of the ultrasonic seal and cut apparatus in accordance with the present invention.

Detailed description of the invention Referring now to the figures and Figure 1 in particular, numeral 10 identifies the end of a weaving loom from which emerges a sheet 12 of textile material whichis driven by means of suitable and well known drive mechanisms 14 and 16 in a continuous manner through an ultrasonic seal and cut station, generally identified by numeral 18. The sealed and cut sheet material is taken up on a storage roller 20 while the selvage 22 is discarded.

The ultrasonic seal and cut station 18 comprises essentially a support 24, see also Figure 2, which supports an ultrasonic converter unit 26 which receives high frequency electrical energy from a generator 28 via an electrical conductor 30. The converter unit 26 contains piezoelectric transducer material for providing, in response to electrical high frequency input power, mechanical vibrations to a horn 32 dimensioned to be resonant along its longitudinal axis at a predetermined high frequency. The converter unit 26 and the horn 32 are designed to be resonant at an ultrasonic high frequency, typical operating frequencies being 20 kHz and 40 kHz. Other suitable frequencies are in the range between 16 and 100 kHz.

The output surface 34 of the horn is opposed by an anvil wheel 36 which will be described in greater detail hereafter. The anvil wheel may be rotating or, as used in the present invention, is clamped against rotation by a centrally disposed screw, and is indexed to expose a new peripheral surface portion to the horn whenever a previously exposed surface portion has become dull or damaged. Either the anvil is spring mounted as shown in the Calemard patent supra, or the converter unit is spring biased against the anvil as shown in U.S. Patent No. 3,734, 805 issued to E. G. Obeda et al. entitled "Ultrasonic Sewing Machine" dated May 22, 1973. The seal and cut station comprising the support 24, the converter unit 26, horn 32 and anvil 36 together with the electrical generator 28 is a commercial unit and available as an "On-Loom Ultrasonic Slitter" from Branson Sonic Power Company, Eagle Road, Danbury, Connecticut 06810 and is described in the Branson Data Sheet PW-36. A similar unit is shown also in the patents to Sulzer and Calemard, supra.

A filament 40 which preferably is a thermoplastic filament, either a monofilament or a multifilament, is unwound from a roller 42 and fed via guide rollers 44, 46, and 48 together with the sheet material 12 to the ultrasonic seal and cut station 18 for becoming fused with the sheet material in the marginal region adjacent to the cut.

Figure 3 shows the result of the present arrangement. Numeral 12 designates the sheet material, for instance an open weave or a sheet of randomly oriented fibers, which has been cut to produce an edge 50. the marginal region 52 adjacent to the cut is filled with thermoplastic material 41 from the filament 40 and the entire region 52 is fused as a result of the dissipation of ultrasonic energy provided by the horn 32. In response to the dissipation of ultrasonic energy, the thermoplastic fibers of the sheet material 12 and the added thermoplastic filament 40 soften, flow under the influence of the pressure applied, and subsequently harden when moving away from the seal and cut station to thereby form a fused mass.

The fused marginal region is a relatively narrow region and provides a finished edge which is not subject to a frayed appearance or to unraveling of threads. This phenomenon has been described in detail in the U.S. Patent No. 3,378,429 to Obeda supra.

Figure 4 shows the constructional details of the horn and opposing anvil with sheet material interposed during the seal and cut process. The anvil 36 has two tapered sealing surfaces 54 and 56 and a centrally located raised cutting surface 58 in the form of a centrally located ridge. The anvil surfaces are opposed by the flat output surface 34 of the horn 32. As previously stated, the anvil and horn are urged toward one another by suitable bias means, such as spring pressure or a combination of spring and fluid pressure and, in addition, the frontal surface of the horn when rendered resonant undergoes motional excursion toward and away from the anvil, which motion is responsible for the cutting action and the dissipation of energy which reflects itself as heat in the sheet material 12 for causing the softening and melting of thermoplastic material.As seen in Figure 4, the sheet material engaged by the sealing surface 54 of the anvil 36 exhibits a large mass of molten material due to the addition of a filament 40, whereas the sheet material 12 in contact with the sealing surface 56 exhibits a smaller mass of molten material since only the thermoplastic fiber content of the sheet material assumes a molten state. The material 12 on the sealing surface 56 is discarded as selvage 22.

As will be readily apparent, the present arrangement in which a filament of thermoplastic material is added is eminently suited for effecting a welded and sealed edge on textile material which contains only a small amount of thermoplastic fibers or when an open weave is to be sealed and cut since, in the latter case, the thermoplastic filament added at the sealing station will be pressed into the interstices of the sheet material, filling the spaces with thermoplastic material, therefore producing a strengthened marginal region adjacent to the cut. In addition, the present arrangement can be used also for effecting a sealed and cut edge in sheet material comprising primarily natural fibers, such as cotton, which fibers are not subject to softening and melting under the influence of ultrasonic energy.

Figure 5 shows the ultrasonic horn 32 and opposing anvil 36 separated from each other prior to the ultrasonic sealing and cutting. The filament 40 is fed over the sealing surface 54 of the anvil 36 and is in contact with the sheet material 12. (As contrasted with Figure 1, the roller 42 and guide roller 44 are disposed below the sheet material 12). In Figure 6 the arrangement corresponds to the illustration per Figure 1 wherein the filament 40 is disposed between the sheet material 12 and the output surface 34 of the horn 32. Responsive to the bias means (not shown) and the application of ultrasonic energy by the horn 32, the fused condition shown in Figure 4 is caused, providing a sealed and cut edge of the sheet material as illustrated in Figure 3.

Figure 7 depicts a further modification. A pair of filaments 40A and 40B is fed over the anvil 36, each filament being in contact with a respective sealing surface 54 and 56. In this manner the sheet material on either side of the cut edge 50, Figure 3, will have a sealed marginal region 52 as may be required in a slitting apparatus where wide sheet material is slit into narrower ribbons and each ribbon edge has to exhibit a finished appearance.

In Figure 10 a filament 40 is fed over the centrally disposed cutting surface 58 of the anvil 36, thus providing substantially equal amounts added thermoplastic material on either side of the cut edge as a result of the softened material being squeezed to either side. Figures 8 and 9 show a further modification wherein the filament 40 is fed through guide means 60 in the output surface of the horn 32 to the sealing and cutting surfaces. The guide means comprises a groove disposed at the underside of the horn.

It should be noted that the filament added to the sheet material at the sealed region can be either of the same color as the sheet material or may be of a different color in order to provide for a decorative appearance. Moreover, the sheet material may be a single ply as shown or can be multiple plies which then become fused together at the cut edge and in the marginal region adjacent to the cut responsive to the dissipation of ultrasonic energy and the melting and fusing of thermoplastic material.

Figure 11 depicts another alternative embodiment of the invention. A horn 32A is coupled to the converter 26, causing mechanical vibrations to be manifest at the output surface 34A of the horn. As shown in Figure 11, the frontal or output end of the horn 32A is a part of a removable tip 66 which is screw fastened to the horn by a stud 68. The tip 66, as will be readily apparent, is easily replaceable when worn or when a change is required. the tip 66 is provided with a bore 70 which is inclined with respect to the longitudinal axis of the horn 32A to permit the filament 40 to be fed from the outside of the horn upon the workpiece 12. The bore terminates at the output surface 34A of the horn.

In a typical example, the material 12 is a polyester fiber blend or natural fibers, and the filament material 40 is nylon, polypropylene, polyethylene, or polyester material, having a diameter of 0.005 to 0.015 inch (0.13 to 0.4mm). The bore 70 is of circular cross-section for receiving a round filament. The replaceable tip 66 has the advantage that several tips may be provided in order to accommodate different filament diameters and the bore has the advantage that extremely precise guidance for the filament is provided.

As seen in Figure 11, the sheet material is passed through the nip between the horn and the anvil in the direction indicated by the arrow. The filament portion fused to the sheet material 12 causes fresh filament material to be drawn through the bore 70 as the sheet material advances through the nip. The center axis 78 of the horn 62 is slightly displaced with respect to the axis 80 through the disk shaped anvil for causing the filament 40 to be fed upon the anvil ahead of the point of maximum compression and, hence, the point of maximum power dissipation, i.e., the region where the gap between the output surface 34A and the anvil 36 is a minimum. This arrangement assures that the filament is first fed upon the sheet material and subsequently fused with the sheet material as the material passes through the seal and cut station.

While there have been described and illustrated several preferred embodiments of the invention and certain modifications have been indicated, it will be apparent to those skilled in the art that still further changes and modifications may be made without departing from the scope of the present invention, which shall be limited only by the scope of the appended claims.

Claims

1. The method of providing a finished edge on sheet material utilising an ultrasonic seal and cut apparatus comprising the steps of: providing an ultrasonic seal and cut station comprising an anvil and an opposing horn adapted to be resonant at an ultrasonic frequency; passing sheet material through said station for causing material disposed between said anvil and said horn to be cut and simultaneously sealed in a marginal region adjacent said cut in response to said horn being resonant and in contact with the sheet material passing over said anvil;; feeding at least one filament adapted to melt responsive to the dissipation of ultrasonic energy provided by said horn simultaneously with the sheet material between said anvil and said horn in a position for causing said filament to melt and become fused with the sheet material in said marginal region, and removing the sealed and cut portion of sheet material from the seal and cut station.

2. The method as claimed in claim 1, in which said filament is a substantially thermoplastic material.

3. The method as claimed in claim 1 or 2, in which said filament is a monofilament.

4. The method as claimed in claim 1 or 2, in which said filament is a multifilament.

5. The method as claimed in any of claims 1 to 4 in which said filament is of the same colour as the sheet material.

6. The method as claimed in any of claims 1 to 4 in which said filament is of a different colour than the sheet material.

7. The method as claimed in any of claims 1 to 6 in which said filament is fed between the sheet material and said anvil.

8. The method as claimed in any of claims 1 to 6 in which said filament is fed between the sheet material and said horn.

9. The method as claimed in any of claims 1 to 6 in which said anvil has a cutting surface and an adjacent tapered sealing surface for providing sealing in the marginal region.

10. The method as claimed in claim 9 in which said filament is fed upon the tapered surface of said anvil.

11. The method as claimed in claim 9 in which said filament is fed upon the cutting surface of said anvil.

12. The method as claimed in any of claims 1 to 6 in which said filament is fed through guide means diposed in the horn.

13. The method as claimed in any of claims 1 to 6 in which said filament is fed through a bore disposed in said horn.

14. The method as claimed in any of claims 1 to 13 in which said sheet material comprises woven or non-woven material and the filament when melted due to the coaction between the anvil and horn penetrates into the interstices of the sheet material.

15. The method as claimed in any of claims 1 to 14 comprising feeding a pair of filaments simultaneously with the sheet material between said anvil and said horn.

16. An ultrasonic seal and cut apparatus for sheet material comprising a seal and cut station in the form of an anvil and an opposing horn adapted to be resonant at an ultrasonic frequency for providing at its output surface ultrasonic energy to the sheet material fed over said anvil, means for feeding sheet material through said station; said anvil having a cutting surface and an adjacent sealing surface; means for feeding a filament, adapted to melt responsive to the dissipation of ultrasonic energy provided by said horn, simultaneously with the sheet material between said anvil and said horn, whereby to cause said cutting surface to cut the sheet material responsive to said horn being resonant and in contact with the sheet material and said filament to melt and become fused with the sheet material in a marginal region adjacent the cut defined by said sealing surface.

17. An ultrasonic seal and cut apparatus as claimed in claim 16, in which said filament is fed between said anvil and the sheet material.

18. An ultrasonic seal and cut apparatus as claimed in claim 16, in which said filament is fed between said horn and the sheet material.

19. An ultrasonic seal and cut apparatus as claimed in claim 18 in which said horn includes means at its output surface for guiding the filament onto the sheet material.

20. An ultrasonic seal and cut apparatus as claimed in claim 19 in which said means for guiding the filament comprises a groove.

21. An ultrasonic seal and cut apparatus as claimed in claim 18 in which said means for guiding the filament comprises a bore extending from the side of the horn angularly inclined relative to the longitudinal axis of said horn to the output surface of said horn for guiding the filament onto the sheet material.

22. An ultrasonic seal and cut apparatus as claimed in claim 16, in which said anvil has a pair of sealing surfaces and a centrally disposed cutting surface, a pair of filaments being fed in a position for causing a respective filament to be acted upon by a respective sealing surface.

23. An ultrasonic seal and cut apparatus as claied in any of claims 16 to 22, in which said horn is resonant at a predetermined frequency in the range between 16 kHz and 100kHz.

24. An ultrasonic seal and cut apparatus as claimed in claim 21 in which said bore is disposed in a resplaceably mounted tip forming a part of said horn.

25. An ultrasonic seal and cut apparatus as claimed in claim 21 in which said bore is of circular cross section.

26. An ultrasonic seal and cut apparatus as claimed in claim 21, in which said anvil includes at least one sealing surface and a cutting surface, said bore terminating for feeding the filament upon the sheet material portion disposed upon said sealing surface.

27. A method of providing a finished edge on sheet material as claimed in claim 1 substantially as hereinbefore described.

28. An ultrasonic seal and cut apparatus as claimed in claim 16 substantially as hereinbefore described with reference to the accompanying drawings.