HK1107295B - Sports racquet with multi-section frame - Google Patents

Description

Sports racquet with multi-section frame

Technical Field

The present invention relates to sports racquets such as tennis racquets, squash racquets, badminton racquets and racquetball racquets. The racket has a head portion containing an interwoven string bed, a handle, and a shaft portion connecting the head portion to the handle.

Background

In a conventional racket, a hole for fixing an end of a string is formed in a frame by drilling a string hole in the frame after the racket is molded. Typically, each wire hole receives one wire. Plastic wire clips (grommets pegs) formed on a wire clip strip extending along the outside surface of the frame extend through the wire holes to protect the wire from the sharp edges of the drilled holes.

Commonly owned PCT application WO2004/075996 discloses a sports racquet in which adjacent pairs of string holes extending along the sides, top and throat bridge of the racquet are replaced by enlarged string holes, one string being placed at each of the opposite ends of the string holes (referred to herein as port strings). Preferably, the frame is made of a double tube of carbon fiber reinforced composite material (so-called carbon frame) in which enlarged string holes are molded in the racquet when the racquet is pressure molded. Since a double tube is used, each tube constitutes half of an enlarged string hole, which may have rounded edges, without the use of a string peg or strip. Furthermore, in the areas between the string holes, the adjoining walls of the double tube are joined together to form an inner reinforcing wall lying in the plane of the string bed. A racket with enhanced torsional strength and lighter weight is finally obtained. The motion performance of a carbon sports racquet can be varied in various ways, for example, by varying the geometry of the frame, the materials used, the number and fiber orientation of the different layers of composite material used at each racquet location, or the overall weight, balance, stiffness, and polarity and mass moment of inertia of the frame. While current racquet designers are generally inclined to design racquets with various playing characteristics, there is a desire for greater flexibility in designing new racquet playing characteristics.

Disclosure of Invention

The present invention provides a racket including a frame formed of a plurality of frame sections. In one embodiment, the head portion and the opposite side of the top portion are each formed from a separate frame portion. Each frame includes a plurality of wire end holes formed either in the frame as disclosed in WO2004/075996 or in the insert. The upper and lower corners of the head portion are separate components with conventional wire holes designed to receive a single wire or a pair of wires. Preferably, the frame lower corner is connected to the stem and handle portions of the frame as a unitary lower frame member.

The corners may be made of a different material than the sides and top. Also, the upper corner and the lower frame member may have a structure different from the structure of the side and top frames. More preferably, the upper corner portion is formed of a single hollow carbon tube, the lower frame member is formed of a pair of single hollow carbon tubes, and the side and top portions are formed of a pair of molded carbon tubes, such that the facing walls of the tubes define a wire end aperture.

If conventional string holes are used for the top portion, the top portion and the upper corner portion can be formed as a single continuous carbon tube member.

The various sections of the racquet may be formed separately and then joined together or integrally formed by a known modified blow molding technique. In a conventional blow molding process, an inflatable bladder is placed in a pre-impregnated tube of uncured composite material. The tube is placed in a mold, which is flexible at this stage, and is in the shape of a racquet frame when the mold is closed. The bladder is then inflated so that when the mold is heated to cure the epoxy, the tube assumes the shape of the mold.

The invention also provides a method for manufacturing a sports racquet, according to which a plurality of pre-impregnated parts are formed. In the portions to be the lower frame portion and the upper corner portion, the prepreg portion is a single tube. In the portions that will become the sides and the top, a double tube is provided. A pair of inflatable balloons extends through each of the single tubes, one balloon extending through each of the double tubes. The prepreg tube may be wrapped with additional prepreg sheets to connect the parts before placing them in the mold.

Within the mould, a number of mould elements are placed at desired positions between the double tubes, the outside surfaces of which form line end holes. The moulding is then carried out in a conventional manner. After the frame is removed from the mold, the mold elements are removed.

Alternatively, the frame portions may be formed separately and then connected. The parts may be manufactured in separate moulds. Each element is designed to be connected by a suitable connection. These connectors may permit and ensure the assembly of a plurality of elements that make up the racquet frame. A mould is used as a reference to ensure accurate positioning of the components and connection to the frame profile. The elements that fit together properly are joined by mechanical joints (obtained by the particular geometry of the elements) or eposidic glue.

The string end holes may have any suitable shape, such as oval, circular, polygonal, inverted circular, convex, concave, or irregular. The use of enlarged string holes reduces the overall weight of the racquet and makes string stringing easier.

Drawings

Other features and advantages of the sports racquet according to the invention will become apparent from the following description of preferred embodiments thereof, taken in conjunction with the accompanying drawings, in which,

FIG. 1 is an exploded perspective view of a tennis racket frame according to an embodiment of the present invention; and the number of the first and second groups,

FIG. 2 is a perspective view of the racquet frame of FIG. 1; and

FIG. 3 is a schematic view of a portion of the side and upper corners during the molding process.

Detailed Description

Fig. 1 and 2 show a tennis racket frame having a plurality of individual parts. In this example, the frame includes a top 10, a pair of sides 12, 14, a pair of upper corners 16 and a lower frame portion 18. The lower frame section 18 includes a lower corner 20 of the head, a pair of convergence rods 22 and a handle portion 240. The lower frame portion 18 also includes a throat bridge 26, if one is used.

As shown in fig. 1, one continuous tubular member forms the lower corner 20, the bar 22 and the half handle on either side of the frame. Further, each upper corner portion 16 is constituted by a single tubular frame member. The side portions 12, 14 are formed of a double tube frame including a plurality of wire end holes 24 formed therein. The throat bridge 26 also includes a plurality of wire end holes 24.

Fig. 3 is a diagram illustrating one method of forming a racquet frame having different frame portions using blow molding techniques. In conventional blow molding of sports racquets, a pre-impregnated tube of uncured composite material is placed in a mold that encloses an inflatable bladder that, when the mold is closed, takes the shape of the desired racquet frame. After the mold is closed, the bladder is inflated so that the tube assumes the shape of the mold, which is heated to cure the composite resin.

In the method of fig. 3, a pair of inflatable balloons is used. Figure 3 schematically shows a portion of the frame where the side portions 14 join the upper corner portions 16 when moulded. The tubular portions 14, 16 are received within a closed mold having mold elements 30, 32.

The corner 16 comprises a single tube of composite material. A pair of air bags 34, 36 are placed in the corner 16. As shown, the bladders 34, 36 meet along a common wall 38 when inflated.

The side portion 14 includes a pair of tubes 40, 42, with the bladder 34 extending within the tube 40 and the bladder 36 extending within the tube 42. When the tubes 40, 42 are inflated with the bladders 34, 36, the tubes meet along a common wall 44 and fuse together to form an inner wall.

As shown in fig. 3, prior to molding, a mold insert 50 is inserted between the upper tube 40 and the lower tube 42 at each location where it is desired to form a line end hole 24. The mold insert 50 has an outer surface having the desired shape of the wire end bore 24. Although the apertures 24 are shown as being oval, they may be any desired shape, such as rectangular, circular, or other shape. Preferably, the mold insert 50 is shaped to form a rounded lip on the outer surface of the bore 24 from which the wire enters and exits.

The prepreg tubes forming the various parts of the frame may be formed by winding prepreg sheets over the air bags on a common mandrel. Preferably, the prepreg sheets are wrapped over the joints 46 between adjacent sections so that the sections are bonded together during the molding process.

Alternatively, the various portions of the frame may be formed separately and subsequently joined using suitable joints.

In the above method, the string end holes 24 are formed/molded in the racket frame. The string holes at the corners may be drilled in a conventional manner. As described in PCT application WO2004/075996, the string-end holes 24 on one side of the frame are offset (as are the top and throat bridges) relative to the string-end holes 24 on the other side of the frame to accommodate threading. Thus, the wire entering one wire end hole is supported on the upper wall of the wire end hole, wound around the outside of the frame and supported on the lower wall of the wire end hole immediately above it. After passing through the wire bed, the wire is supported on the upper wall of the opposite (offset) wire end hole, wound around the outside of the frame and supported on the lower wall of the wire end hole immediately above it.

In the above example, each frame portion is made of a carbon fiber reinforced composite material. The type of composite material may be different or the same in each section. Furthermore, the parts may be made of different materials, such as a combination of composite materials, metals, such as aluminum, nanomaterials, plastics or wood, etc.

As used herein, the term "side" or "side" generally refers to the area of the head between the upper and lower corners, and the "top" generally refers to the area of the head between the upper corners. However, as these terms are not technical terms, as used herein, "sides" and "top" may include any portion of a side or top, or even a portion that one considers to be a corner.

The foregoing description of the preferred embodiments of the invention has been presented. Variations and modifications thereof will be apparent to those skilled in the art without departing from the inventive concepts disclosed herein. For example, the top portion may use conventional string holes instead of string end holes if desired, wherein the top portion and upper corner portion may be made from a single continuous prepreg tube. In another example, the top portion may be made of a double tube aluminum profile, the side portions are made of a single carbon fiber tube, and the end holes are formed as shown in FIGS. 1-3. Such modifications and variations fall within the scope of the invention as defined by the following claims.

Claims (9)

1. A sports racquet comprising a frame including a pair of opposed side portions (12, 14), a top portion (10) and a pair of upper corner portions (16) connecting and separating the side portions (12, 14) and the top portion (10), characterised in that said upper corner portions (16) are formed from a single tubular member and said side portions (12, 14) are formed from a pair of tubular members.

2. A sports racquet, as set forth in claim 1, characterized in that each side portion (12, 14) includes a plurality of string end holes (24).

3. A sports racquet, as set forth in claim 1, characterized in that said top portion (10) is formed by a pair of tubular members.

4. A sports racquet, according to claim 1, characterized in that said top portion (10) is constituted by a single tubular piece.

5. A sports racquet, as set forth in claim 1, characterized in that said side portions (12, 14) and upper corner portion (16) are made of different materials.

6. A sports racquet, as set forth in claim 1, characterized in that said frame includes a pair of lower corners (20) connecting said sides (12, 14), and wherein each of said lower corners (20) is formed from a single tubular member.

7. A sports racquet, as set forth in claim 1, characterized in that said frame comprises a pair of converging bars (22) and a handle portion (240) connected to said bars (22), each bar being connected to a lower corner (20), and wherein said lower corners (20), bars (22) and handle portion (240) are formed from a pair of tubular members.

8. A method of manufacturing a sports racquet having side portions (12, 14) and an upper corner portion (16), characterized in that it comprises the steps of:

forming a pair of side portions (12, 14) and a pair of upper corner portions (16), the side portions (12, 14) being formed from a pair of tubular members, each upper corner portion being formed from a single tubular member;

each upper corner (16) is connected to the side portion (12, 14).

9. A method according to claim 8, comprising the steps of providing a pair of prepreg tubes forming one of said side portions (12, 14), providing a single prepreg tube forming an upper corner portion (16); connecting the single prepreg tube and the ends of the pair of tubes at a joint area; providing a pair of inflatable bladders (34, 36); introducing one of said inflatable bladders (34, 36) through each of said pair of prepreg tubes, said pair of inflatable bladders being introduced through said single prepreg tube; positioning the prepreg tube in a mold; positioning a plurality of mold inserts (50) between the pair of prepregs, each insert shaped to form a wire end hole (24); inflating the pair of inflatable bladders (34, 36) while heating the mold to form the frame; removing the mold insert (50) from within the frame.