EP0108093B1 - Verfahren zum herstellen von bespannungssaiten für ballschläger, insbesondere für tennisschläger - Google Patents

Verfahren zum herstellen von bespannungssaiten für ballschläger, insbesondere für tennisschläger Download PDF

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Publication number
EP0108093B1
EP0108093B1 EP83901362A EP83901362A EP0108093B1 EP 0108093 B1 EP0108093 B1 EP 0108093B1 EP 83901362 A EP83901362 A EP 83901362A EP 83901362 A EP83901362 A EP 83901362A EP 0108093 B1 EP0108093 B1 EP 0108093B1
Authority
EP
European Patent Office
Prior art keywords
plastic film
film strips
process according
string
winding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP83901362A
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German (de)
English (en)
French (fr)
Other versions
EP0108093A1 (de
Inventor
Herbert Woltron
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Isosport Verbundbauteile GmbH
Original Assignee
Isosport Verbundbauteile GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Isosport Verbundbauteile GmbH filed Critical Isosport Verbundbauteile GmbH
Publication of EP0108093A1 publication Critical patent/EP0108093A1/de
Application granted granted Critical
Publication of EP0108093B1 publication Critical patent/EP0108093B1/de
Expired legal-status Critical Current

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    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B51/00—Stringing tennis, badminton or like rackets; Strings therefor; Maintenance of racket strings
    • A63B51/02—Strings; String substitutes; Products applied on strings, e.g. for protection against humidity or wear
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core
    • Y10T428/2936—Wound or wrapped core or coating [i.e., spiral or helical]

Definitions

  • the invention relates to a method for producing a string for ball rackets, in particular for tennis rackets, in which a plurality of winding layers of helically wound plastic film tapes are applied to a continuously supplied core one above the other along at least approximately concentric cylindrical surfaces and the winding layers are connected to one another and to the core.
  • a method of the type mentioned above is known from US-A-3,024,589.
  • this method e.g. B. a continuously fed nylon thread impregnated as a core with a liquid binder, then helically wound in two superimposed winding layers with opposite directions of wrap and the excess binder stripped.
  • the wet strand thus formed then passes through heated tubes, is dried and finally pulled off and wound up as a finished string.
  • further pairs of winding layers can be applied to the wet strand, but the strand must be impregnated again with the liquid binder before each application of a pair of winding layers.
  • extruded tapes can also be used as the winding material.
  • the string known from the above-mentioned US Pat. No. 3,024,589 is said to have properties which approximate the intestinal strings used for strings for ball rackets.
  • the production of such intestinal strings is based on sheep or cattle intestines, which are cut into ribbons and subjected to treatment by chemical processes. Several of these tapes are then twisted together to produce the string.
  • These gut strings now have the property that the dependence of the stretch on the applied tensile force is largely linear, i. H. the elastic modulus of the string material is largely constant and therefore also independent of the pretension with which the string was applied to the racket.
  • a disadvantage of casing string covering is, on the one hand, the quality differences that cannot be avoided in their manufacture, which are due to the quality fluctuations of the casing material used, and, on the other hand, their high moisture absorption, which is due to the resulting strong change in length, e.g. B. at high humidity the playability of rackets with gut string covering impaired.
  • gut string production is relatively expensive.
  • plastic strings which usually consist of a plastic monofilament, now have spring constant characteristics of a type such as that used for. 1 are given by curve B in FIG. 1:
  • the spring constant E. A. is larger in the range of the string tension in question from 200 to 300 N than in comparable gut strings and also increases substantially linearly with increasing tension with a relatively large pitch. It follows from this that the deformations of the stringing that occur when the ball hits the racket are less than with comparable gut stringing and that the force peaks to be absorbed by the racket for decelerating a certain kinetic energy of the ball are correspondingly higher than with gut stringing.
  • a commercially available string made of polyamide (nylon) of the type described in US-A-3,024,589 does not have an improved spring constant characteristic compared to a string made of a polyamide monofilament and, at least as far as this aspect is concerned, does not match the properties of Gut strings.
  • the invention is based on the object of specifying a method for producing string strings for ball rackets, in particular for tennis rackets, in which a plurality of winding layers of helically wound plastic film strips are applied to one another on a continuously supplied core one above the other along at least approximately concentric cylindrical surfaces and the winding layers are connected to one another is less complex than the known method mentioned in the prior art and leads to string strings which have a similar flat spring tension characteristic as gut strings and which, however, do not suffer from the disadvantages inherent in the gut strings.
  • the object on which the invention is based is achieved in the method according to the invention, which is characterized in that those made of monoaxially stretched plastics are used as plastic tapes and that after winding the core with the winding layers of the like generated winding composite is guided under tension through a welding zone, in which the plastic film tapes form a welded connection with one another at elevated temperature.
  • the temperature in the welding zone is advantageously set so high that a weld connection already occurs between the plastic film tapes, but this temperature treatment does not yet significantly reduce the tensile strength aR of the monoaxially stretched plastic film tapes used in winding layers, and advantageously with the result that that, in the event that the string is built up at least essentially from plastic film tapes of a uniform material, the temperature in the welding zone is set such that the reduction in the tear strength of the plastic film tapes during the welding process leads to a tensile strength of the finished string that does not exceed 20% , advantageous but not more than 15% below the tear strength value of the plastic film tapes used.
  • the monoaxially stretched plastic film tapes used are those made from olefins of high molecular weight, which preferably contain polypropylene homopolymers or polypropylene-polyethylene copolymers.
  • those made of polypropylene-polyethylene-diene terpolymers of high molecular weight are used as monoaxially stretched plastic film tapes.
  • the material of the plastic film strips used contains a nucleating agent, which can preferably be one based on an organometallic complex compound.
  • Such nucleating agents increase the number of crystallites in the ribbon material, which, as the applicant has found, reduces the tendency of the monoaxially stretched ribbon tapes used to creep.
  • the preheating devices in order to prepare the welding of the winding assembly, it is preheated during its manufacture in one or more preheating devices, each of which is switched between two successive winding operations, advantageously at least in part of the preheating devices on the surface of the partial winding assembly produced up to that point is smoothed.
  • Fig. 2 shows a schematic representation of a preferred system for producing the string.
  • the system comprises six consecutively arranged, essentially identical winding devices 1 to 6, of which only the winding devices 1, 2 and 6 are shown in FIG. 1, a heated tubular welding device 7, and five preheating nozzles each arranged between two successive winding devices, of which only the preheating nozzles 8 and 9 are shown.
  • the still warm finished string 13 passes through a calibration device 14 consisting of two grooved rollers, is pulled off by a pull-off device 15 in the direction of arrow 16 and finally wound up at 17.
  • each of the winding devices comprises a rotary star 18 with up to four pivotably mounted coils 21 with trigger brakes 19 and with adjustable guide eyes 20 for the plastic film strips 22.
  • Each rotary star 18 is equipped with a separate drive with a continuously adjustable speed.
  • Fig. 4 shows schematically the winding course of a film strip of the winding layers, which occupy the two outermost layers 23 and 24 of the string. It is explained in more detail with reference to the following description of the embodiment of the invention.
  • 35 J.Lm thick and 3 mm wide tapes 22 made of an extruded polypropylene-polyethylene-diene terpolymer, which was then cold-stretched with a stretching ratio of 1: 6.5, were used. These tapes 22 are wound on spools 21 and the first four rotating stars 18 in the conveying direction 16 are each equipped with three spools 21 and the remaining two rotating stars 18 each with two spools 21. This results in a winding sequence referred to below as 3/3/3/3/2/2.
  • the tapes 22 of each spool 21 are first passed through all preheating nozzles 8, 9 lying in the drawing-off direction 16 and through the welding device 7 and first together as a bundle from the drawing-off device 15 at a constant speed in the range between 1 to 2 m / min in the drawing-off direction 16 deducted.
  • the string is formed as follows: in the first winding device 1, to which no pre-strand is fed, one of the wound foil tapes 22 has a twisted structure which the other two tapes are applied as more or less uniform winding layers.
  • the part-winding composite so produced 25 then passes through the first pre-heating 8 in which it is heated to a temperature which occurs when no welding nor the small film strips, but in which the strip material is elastic, whereby which is made in the pre-heating 8 Upper f lamba Smoothing the partial winding assembly 25 is facilitated.
  • the pre-strand 26 emerging from the first preheating nozzle now serves as the core for the winding layers applied in the subsequent winding devices 2 to 6 along concentric cylindrical surfaces made of overlapping and helically wound foil strips 22.
  • Fig. 4 shows the winding course of a foil tape 27 and 28 of winding layers, which occupy the two outermost layers 23 and 24 of the string.
  • the pitch of the windings is determined by the take-off speed measured in front of the welding device 7, the speed of the rotary star 18 and the diameter of the respective strand. It increases from winding position to winding position from approximately 45 ° to 65 °.
  • the angle a (FIG. 3) with which the film strip 22 runs towards the winding point 29 is in each case set to a constant value; the location of the winding point 29 is determined by adjusting the position of the guide eyelet 20 accordingly.
  • the film strips 22 are under tensile stress during winding and because of the helical winding structure, there is a not inconsiderable contact pressure between the wound film strips 22 and the pre-strand 26 serving as the winding substrate, which in the preheating nozzle upstream to a temperature below the welding temperature brought and smoothed surface.
  • These strands each form compact winding structures that do not contain any notable air pockets.
  • the preheated winding assembly 30 is brought to a temperature at which, within this assembly, the film strips 22 lying flat against one another and - as explained above - are well welded to one another, but the anisotropy existing in the film material due to the cold deformation is not significantly disturbed, which is what means that the tensile strength of the film strips used is not significantly reduced by this temperature treatment.
  • this has the effect that the tensile strength of the finished string is 390 N / mm 2 , which is less than the tensile strength of the film strips used, which is 420 N / mm 2 here.
  • the still warm string 13 running from the welding device 7 then passes through the calibration device 14, in which it is calibrated to a diameter of 1.20 mm in the present production example, after which it is pulled off the take-off device 15 in a largely cooled state and wound up at 17 becomes.
  • the finished string 13 has a spring constant characteristic according to curve C shown in FIG. 1.
  • the values of the spring constant EA are substantially lower in the range of the string pretension F " of 200 to 300 N that comes into question in practice and increase significantly less with increasing pretension F " than with comparable known synthetic strings (curve B).
  • the increase in the characteristic (curve C) is only a little steeper than the increase in the characteristic of gut strings (curve A).
  • Example D 1 In production examples C 2 , C 3 , D 1 and D 2 , the same polypropylene-polyethylene diene terpolymer is used as the film base material as in production example C 1 described in detail above, with a different degree of stretching of the film strips used: 1: 6.5 (for C 1 , C 2 and C 3 ) and of 1: 8 (for D 1 and D 2 ). Furthermore, in deviation from the other examples in Example D 1 , only five winding layers are applied instead of six.
  • the polypropylene homopolymer used as the film material according to Example E contains about 1% of the nucleating agent of the type PP-78040 based on an organometallic complex compound, as supplied by Gabriel-Chemie, Vienna.
  • the strings according to production examples C 2 and C 3 like the string according to example C 1 , have a spring tension characteristic according to curve C in FIG. 1, the strings according to examples D 1 and D 2 have a characteristic according to curve D and the string according to example E, the curve correspondingly designated E.
  • the string made according to the method of the invention can be used particularly advantageously for tennis racket stringing.
  • the properties of such a stringing approximate those of a gut string stringing.
  • the production costs of the string according to the invention are, however, considerably lower than those of a corresponding gut string.

Landscapes

  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Physical Education & Sports Medicine (AREA)
  • Laminated Bodies (AREA)
  • Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
  • Shaping Of Tube Ends By Bending Or Straightening (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)
  • Moulding By Coating Moulds (AREA)
EP83901362A 1982-05-12 1983-05-13 Verfahren zum herstellen von bespannungssaiten für ballschläger, insbesondere für tennisschläger Expired EP0108093B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT1858/82 1982-05-12
AT0185882A AT389642B (de) 1982-05-12 1982-05-12 Verfahren zur herstellung einer bespannungssaite fuer ballschlaeger, insbesondere fuer tennisschlaeger

Publications (2)

Publication Number Publication Date
EP0108093A1 EP0108093A1 (de) 1984-05-16
EP0108093B1 true EP0108093B1 (de) 1987-09-09

Family

ID=3522524

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83901362A Expired EP0108093B1 (de) 1982-05-12 1983-05-13 Verfahren zum herstellen von bespannungssaiten für ballschläger, insbesondere für tennisschläger

Country Status (8)

Country Link
US (1) US4568415A (ja)
EP (1) EP0108093B1 (ja)
JP (1) JPS59500822A (ja)
AT (2) AT389642B (ja)
AU (1) AU559233B2 (ja)
DE (1) DE3373436D1 (ja)
IT (1) IT1163341B (ja)
WO (1) WO1983003998A1 (ja)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT388301B (de) * 1984-11-09 1989-06-12 Isosport Verbundbauteile Verfahren zum herstellen einer bespannungssaite in lieferform fuer ballschlaeger, danach hergestellte bespannungssaite sowie verfahren zum bespannen von ballschlaegern mit dieser saite
US5327714A (en) * 1992-07-30 1994-07-12 Prince Manufacturing, Inc. Synthetic string for sporting application
DE4242673A1 (de) * 1992-12-17 1994-06-23 Siegfried Kuebler Saitenstrang oder Saite zum Bespannen eines Schlägers für Ballspiele
US6132325A (en) * 1997-06-25 2000-10-17 Bertolotti; Fabio P Interlocking string network for sport rackets
US6506134B2 (en) 1997-06-25 2003-01-14 Fabio Paolo Bertolotti Interlocking string network for sports rackets
US6499524B1 (en) * 1999-09-07 2002-12-31 Berol Corporation Dispenser for applying a material to a surface
US6601631B1 (en) * 1999-09-07 2003-08-05 Berol Corporation Dispenser for applying a material to a surface
US20060084532A1 (en) * 2004-10-20 2006-04-20 Chaokang Chu Strings for racquets
AU2009301171A1 (en) * 2008-10-07 2010-04-15 Dsm Ip Assets B.V. Load bearing sheet comprising reinforcing tapes
CN104233547A (zh) * 2013-06-20 2014-12-24 郑州中远防务材料有限公司 单纱、单纱制品及其制备方法
ES2938855T3 (es) * 2015-07-22 2023-04-17 Teufelberger Fiber Rope Gmbh Cable de material de fibras textil

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB775093A (en) * 1956-03-06 1957-05-22 Dunlop Rubber Co Improvements in cords
US3050431A (en) * 1958-07-07 1962-08-21 Ashaway Line & Twine Mfg Manufacture of tennis strings
US3164952A (en) * 1962-07-03 1965-01-12 Dunlop Rubber Co Method of making tennis cords
AT359882B (de) * 1977-05-02 1980-12-10 Fischer Gmbh Bespannungssaite aus kunststoff fuer ball- schlaeger, insbesondere tennisschlaeger
DE2805066C2 (de) * 1977-02-10 1987-04-30 Fischer Ges.m.b.H., Ried Verfahren zur Herstellung von Bespannungssaiten aus Kunststoff für Ballschläger
US4168606A (en) * 1977-05-31 1979-09-25 The Goodyear Tire & Rubber Company Process for forming string
US4275117A (en) * 1977-09-02 1981-06-23 Ashaway Line & Twine Mfg. Co. String construction produced by subjecting a fibrous strand composed of fibrous materials having differing melting points to heating conditions sufficient to melt some but not all of the fibrous materials
JPS5519107A (en) * 1978-07-27 1980-02-09 Kureha Chemical Ind Co Ltd Gut and its preparation

Also Published As

Publication number Publication date
ATE29427T1 (de) 1987-09-15
IT8321032A1 (it) 1984-11-11
EP0108093A1 (de) 1984-05-16
JPS59500822A (ja) 1984-05-10
DE3373436D1 (en) 1987-10-15
WO1983003998A1 (fr) 1983-11-24
IT8321032A0 (it) 1983-05-11
US4568415A (en) 1986-02-04
AT389642B (de) 1990-01-10
JPH0238703B2 (ja) 1990-08-31
AU559233B2 (en) 1987-02-26
ATA185882A (de) 1989-06-15
AU1557183A (en) 1983-12-02
IT1163341B (it) 1987-04-08

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