AN ARTIFICIAL FEATHER FOR SHUTTLECOCKS AND METHOD OF MANUFACTURING SUCH A FEATHER

Abstract: The feather comprises a shaft (1) and projecting vane portions (2, 3) manufactured in one piece by heat forming, e.g. heat pressing, of a blank from a plast material, e.g. a thermoplast, such as polyurethane with fiber reinforcement of the shaft (1), e.g. carbon fibers in a composite material, the vane portions (2, 3) being formed integrally with the remainder of the shaft cross-section obtained by the heat pressing a final thickness of less than 0,2 mm and properties substantially corresponding to those of natural feathers.

Description: An artificial feather for shuttlecocks and method of manufacturing such a feather. This invention relates to an artificial feather for shuttlecocks comprising a shaft and vane portions formed from a plastic material integrally with the shaft and projecting in opposite directions therefrom. From DK patent specification No. 142,804 an arti¬ ficial feather for shuttlecocks is known constituted by a shaft and vane portions of separate elements which may be produced from epoxy moulded carbon fibers and ex¬ truded and stretched polypropylene blanks, respectively, and which may for instance be assembled by means of par¬ ticular adhesive tapes in the longitudinal direction of the shaft. From European published patent specification No. EP-A-0045825 it is likewise known to form artificial feathers for shuttlecocks by first producing vane por¬ tions from woven or unwoven fabric, following which said vane portions are placed in a mould in which the shaft is subsequently prepared by injection moulding in a central axis portion of the mould. The manufacture of such feathers is complicated and made expensive by the fact that several working steps are involved and it is difficult to produce the feathers with a weight that is just as low as the weight of natural feathers. It is further known from GB patent No. 1,402,985 to manufacture an artificial feather with shaft and vane portions in one piece by injection moulding of polypro¬ pylene. However, it has been found that shuttlecocks with such feathers do not meet the demands on strength and weight. The above problems are fully solved by an arti¬ ficial feather which according to the -invention is characterized in that the cross-section of the shaft comprises throughout the length of the shaft at least one fiber reinforced portion of a relatively high ther¬ mal resistance to deformation while the remaining por- tion of the cross-section of the shaft is made from a plastic material which is inseparably united with the plastic material in the vane portions by heat forming at a temperature at which the fiber reinforced portion is substantially not exposed to deformation. Through a series of tests is has surprisingly turned out that due to the combination of a shaft with a cross-section at least one portion of which is consti¬ tuted by a fiber reinforcement while the remaining por¬ tion is integral with the vane portions, and the produc- tion of the feathers by ' heat forming in one working operation allowing a very slight thickness of the vane portions, feathers can be manufactured having properties corresponding to an extremely high degree to those of natural feathers with respect to size, weight and weight distribution between shaft and vane portions as well as to strength, stiffness and resiliency. Compared to the above mentioned prior artificial feathers the production is less complicated so that costs are reduced, and above all, unlike prior artifi- cial feathers shuttlecocks of feathers according to the invention can be manufactured with the same number of feathers and with stroke and flight properties so close to those of shuttlecocks made from natural goose feathers that they can substitute the latter even in badminton matches at a high level, e.g. in international competition or championships. The invention also relates to a method suitable of manufacturing the above mentioned artificial feathers, which method is characterized in that the vane portions and the shaf are formed in one operation by heat forming of said plastic material or materials in a mould in which said fiber reinforced portion or portions have been placed beforehand. The invention will be explained in more detail in the following with reference to the schematical drawings in which Fig. 1 is a plane view of an embodiment of an artificial feather according to the invention, Figs 2 and 3 an enlarged perspective view and a cross-sectional view along the line III-III in Fig. 1 of a first embodiment, Figs 4 and 5 corresponding views of a second em¬ bodiment, Fig. 6 a lateral view of a modification with rib reinforced vane portions, and Fig. 7 illustrates the manufacture of the feather. The artificial feather for shuttlecocks illu¬ strated almost in double size in Figs 1 and 2 consists of a shaft 1 and two vane portions 2 and 3 projecting from the shaft 1 in opposite directions. The vane portions 2 and 3 have a plane shape and a weight corresponding substantially to that of natural feathers for shuttlecocks, for instance a vane area of about 4,5 cm^. The vane portions are preferably made from polyurethane but they may be manufactured from any other thermoplast or ther osetting plast like, for in¬ stance, polypropylene which is suitable for heat forming at a temperature as specified in the following and they may have a thickness of 0,06-0,20 mm, while the shaft may have a. length of ,5 cm. As shown in Figs 2 and 3 the cross-section of the shaft 1 includes throughout the length of the shaft at least one fiber reinforced portion 4 having a relatively high thermal resistance to deformation, i.e. a relati- vely high melting point. Preferably, this portion con¬ sists of carbon fibers bound in a composite material containing fibers, e.g. in an amount of 50 per cent, by volume. The material "Aromatic Polymer Composite APC 1" from ICI may. be used as an appropriate composite materi¬ al for the fiber reinforced portion 4 of the shaft 1, said material containing about 52% carbon fibers of the type -"Vitrex PEEK". In the finished feather the fiber reinforced por- tion 4 of the shaft 1 may, as illustrated in Figs 2 and 3, constitute a solid central core, while the remaining portion of the cross-section of the shaft may have the form of a thin layer surrounding the fiber reinforced portion on all sides. The layer 5 may have a thickness e.g. of 0,15 mm and, according to the invention, it is made from a plastic material which can be inseparably united with the plastic material in the vane portions 2 and 3 as well as the binder used in the composite mater¬ ial in the fiber reinforced shaft portion by a heat forming process to be explained in the following so that in the feather as a whole the shaft 1 is integrally formed with the vane portions 2 and 3. As an alternative, the shaft may, as illustrated in Figs 4 and 5, be designed as a sandwich structure with layers 7 and 8 of the fiber reinforced composite material on opposite sides of a core layer 6 of a plastic material as mentioned above. On the external sides of the layers 7 and 8 the sandwich structure may comprise thin outer layers, not shown, of the same material as the core layer. As shown in Figs 2 and 4, at least on that part of its length where it is connected with the vane por¬ tions 2, 3 the shaft 1 has preferably decreasing cross- section in the direction towards its free end. In Figs 2 and 4 this part of the shaft is formed into a wedge shape, but it may also have a more conical form and it may extend throughout the length of the shaft. In the embodiment shown in Figs 2 and 3 the de¬ creasing cross-section is obtained by manufacturing the fiber reinforced core 4 from a number of thin layers 4a, each having a thickness of e.g. 0,1 mm, of said com¬ posite material with a variation in length of said layers across said portion of the length of the shaft. In order to obtain a good stiffness in the trans- verse direction of the feather the vane portions 2' and 3' may, as shown in Fig. 6, be provided with reinforcing ribs 11. Said ribs 11 may have a thickness e.g. of 0,5-0,6 mm and may extend in a desired transverse direc¬ tion relative to the shaft 1 ' and may include fiber reinforcement. The feather may for instance be manufactured by heat pressing a rodshaped blank provided by co-extrusion of a wireshaped core of a composite material, e.g. of the above type, with a surrounding layer of a •thermo plast that is preferably polyurethane. The heat pressing is effected at a temperature above the melting point of the thermo plast which as regard the above mentioned material is about 190°C but not so high as to expose the fiber reinforced core portion 4 to deformation. The feather obtains its final shape by the heat pressing with the vane portions 2 and 3 and the shaft portion having a thickness of e.g. 0,06-0,20 mm as mentioned above and the shaft having an average thickness of 1 mm. Said forming of the feather by pressing of said rodshaped blank gives considerably good possibilities of providing any desired variation in thickness and an accuracy of proportions considerably improved in rela¬ tion to prior artificial feathers and with very narrow tolerances for obtaining a desired strength and stiff- ness. In the pressing operation purely schematically illustrated in Fig. 7 a co-extruded or pressed rodshaped blank 12 of the above composition is used as starting material for manufacturing a feather as shown in Figs 2 and 3. The blank 12 which as shown may have a rectangu¬ lar cross-section with a width matching the final width of the shaft 1 consists of the fiber reinforced core 4 surrounded by said plastic material in a quantity suf- ficient to produce the vane portions 2 and 3. In the illustrated pressing operation in a pressing mould with halves 9 and 10 projecting vane portions are formed on part of the length of the rodshaped blank 12. The final shape of the vane portions, e.g. as shown in Fig. 1, can be effected in one operation without any successive punching operation. During the pressing operation the plastic material around the fiber reinforced portion 4 will flow outwards from the blank 12. The method described above may in principle also be used for manufacturing a feather having a sandwich structure as shown in Figs 4 and 5 with the modification that the mould halves must be designed to allow the ma¬ terial in the central core layer to flow outwards from the shaft part of the mould. Instead of heat forming in a heated mould of a starting material at comparatively low temperature the manufacturing may be effected by forming in a cold or partially heated mould from a starting material heated to a temperature close to its melting point, said start¬ ing material including such fiber reinforced shaft por¬ tion and the necessary amount of plastic material for the vanes and the remaining shaft portion which material may be present in the form of a heated film. The invention is not restricted to the above spe¬ cified embodiments. Principally, the vane -portions and said remaining shaft portion of the feater may be manu¬ factured from any plastic material that is mouldable by pressing when heated.

Claims: PATENT CLAIMS 1. An artificial feather for shuttlecocks com¬ prising a shaft (1) and vane portions (2, 3) formed from a plastic material integrally with the shaft and projecting in opposite directions therefrom, charac¬ terized in that the cross-section of the shaft (1) comprises throughout the length of the shaft at least one fiber reinforced portion (4; 7, 8) of a relatively high thermal resistance to deformation while the remain- ing portion of the cross-section of the shaft (5, 6) is made from a plastic material which is inseparably united with the plastic material in the vane portions (2, 3) by heat forming at a temperature at which the fiber rein¬ forced portion is substantially not exposed to deforma- tion. 2. An artificial feather as claimed in claim 1, characterized in that the fiber reinforced portion (14) constitutes a central core of the shaft surrounded on all sides by said remaining portion (5). 3. An artificial feather as claimed in claim 1, characterized in that the shaft is designed as a sand¬ wich structure with fiber reinforced layers (7, 8) on opposite sides of a core layer (6) constituting at least a part of said remaining portion. 4. An artificial feather as claimed in claim 1, 2 or 3, characterized in that the shaft is designed with decreasing cross-section in the direction towards its free end. 5. An artificial feather as claimed in any of the preceding claims, characterized in that the fiber rein¬ forced portion (4; 7, 8) of the shaft consists of a com¬ posite material containing carbon fibers. 6. An artificial feather as claimed in any of claims 1 to 5, characterized in that the vane portions (2 1 , 3') comprise reinforcing ribs (11) extending in a suitable transverse direction relative to the shaft (1'). 7. An artificial feather as claimed in any of the preceding claims, ' characterized in that the vane por- tions and/or said remaining portion of the shaft are manufactured from polyurethane. 8. A method of manufacturing an artificial feather for shuttlecocks as claimed in any of the pre¬ ceding claims, characterized in that the vane portions and the shaft are formed in one operation by heat form¬ ing of said plastic material or materials in a mould in which said fiber reinforced portion or portions (4; 7, 8) are placed beforehand. 9. A method as claimed in claim 8, characterized in that the forming of said remaining portions of the shaft and the vane portions is effected by heat press¬ ing of a single plastic material with controlled flow direction of the plastic material outwards from said remaining portion of the shaft. 10. A method as claimed in claim 8, characterized in that the forming is effected by forming of heated plastic material in a cold or partially heated mould.

Inventors: KAMSTRUP-LARSEN JOERGEN, KAMSTRUP-LARSEN, JOERGEN
Applicants: CARBON BALL APS
Application year: 1985
Main classification: A63B67
IPC codes: A63B67