SU1695958A1 - Table tennis racket and method of its manufacture - Google Patents

Abstract

The invention improves the quality of the racquets and simplifies their assembly. The racket consists of a handle and a shock part. The latter includes wood core 1 and outer plates 2 and 3. Between them are reinforcing layers 4-6 of carbon fibers. The reinforcement layers are adjacent to one another and have mutually perpendicular fiber directions. In the manufacture of the racket, an adhesive is applied to the core. The reinforcement layers are formed directly on the core by laying carbon fibers, first across the core fibers, and then along. Then, with the help of auxiliary plates with a glossy surface, a package of layers is formed by simultaneously gluing and forming reinforcing layers. After removing the visual inspection plates and removing the defects, the outer wood plates are glued. 2c. and 2 z. p. f-ly, 5 ill.

Description

FIG. five

The invention relates to sports equipment, in particular to table tennis equipment.

The aim of the invention is to improve the playing properties of the racket by increasing the uniformity of the rebound of the ball over the entire area.

Figure 1 shows a table tennis racket, top view; nafig.2 same side view; fig.Z - the same, top view showing all layers of the racket; figure 4 - node I in figure 2; Figure 5 shows the curves for the rebound rate of the ball on the impact force at different thickness of carbon fibers.

The racket contains a handle and a striking part, the latter consisting of a central wooden plate — core 1 and peripheral wooden plates 2 and 3, between which reinforcing layers 4-7 of carbon fiber are located. The carbon fibers of layers 4 and 5 adjacent to the surfaces of the cores are perpendicular to the fibers of the wood. The fibers of layers b and 7, respectively, adjacent to layers 4 and 5, are arranged perpendicular to the carbon fibers of layers 4 and 5. The thickness of the carbon fibers is the same and is 0.1-0.2 mm.

EXAMPLE 1. A racket has a central wooden plate 1 made of balsa 4 mm thick. The thickness of each reinforcing layer 4-7 of carbon fiber is equal to 0.1 mm, the outer wooden layers 2 and 3 of the resonant spruce 1.3 mm thick. The total thickness of the layers of the racket is 7 mm, the mass of the racket is 80 g.

EXAMPLE 2. A racket has a central wood plate 1 of 3 mm abacha. The thickness of each carbon fiber reinforcement layer is 0.2 mm, the outer wood layers are made of resonant spruce with a thickness of 1 mm. The total thickness of all layers of the racket is 5.4 mm, the mass of the racket is 85 g.

Make a racket as follows.

An epoxy based adhesive is applied to both sides of the central wood panel 1. Then carbon fibers of layers 4 and 5 are applied across the central wooden plate 1, then carbon fibers of layers 6 and 7 are applied along the central wooden plate 1. The resulting package is compressed using auxiliary surfaces with a pressure-impermeable glue with a pressure of 0.01-0 , 5 MPa and maintained at 60-100 ° C for 2 hours. After holding at room temperature for 30 minutes, the pressing force is removed, the auxiliary plates are removed and the condition of the external surfaces is monitored. Qualitatively impregnated and glued reinforcement layers 4-7 should have glossy outer surfaces.

The use of plates with a glossy surface does not only improve the uniformity of the impregnation of the reinforcing layers. The surface of the reinforcement layers thus created is a measure of the quality of the impregnation. Places where there is insufficient glue have a matte surface or shiny fibers that are not impregnated with glue are visible. In this case, glue is applied to these places, superimposed -plates with

the glossy surface is compressed and hardened by heating.

Even at significant pressures, when the central wood plate is deformed, excess glue does not always flow out of the plate and forms irregularities, roughness, which are removed by cycling and grinding. Then glue the outer glue with the same glue

wooden plates 2 and 3. Thus, the method allows to simplify the assembly technology of the racket by combining the operations of forming the reinforcement layers and gluing them together with the core.

Carbon fibers have a modulus of elasticity 1-2 orders of magnitude higher than wood, so they largely determine the playing properties of a racket. When the racket has sufficient contact time with the ball,

and the dependence of the rebound speed on the impact force is close to linear, the term is used that the racket has a high feeling of the ball. Increasing the thickness of the fibers reduces the contact time between the rocket and the rocket.

This increases the speed of rebound of the ball with weak blows, and with strong blows it decreases. Decreasing the fiber thickness increases the contact time of the ball with the racket, but decreases the speed of the ball rebound.

Figure 5 shows the curves of the dependences of the rebound velocity m cha v on the impact force d, obtained as a result of experiments. Curve I corresponds to a fiber thickness of 0.2 mm; curve II - 0.15 mm, curve III - 0.11 mm;

curve IV - 0.08 mm. The most acceptable thickness of carbon fibers, satisfying the game properties, 0.11-0.15 mm.

Thus, the proposed method of manufacturing a racket allows to obtain

a more uniform structure of the bonded layers, since it ensures uniformity of carbon fiber impregnation and the possibility of visual inspection of the state of the outer surfaces after removing the auxiliary plates.

Claims (4)

1. A table tennis racket containing a handle with a striking part including a wood core and an adhesive carbon fiber reinforcement layers associated with it, and outer wood plates, in order to enhance the playing properties of the racket by to increase the uniformity of the rebound over the entire area, it is provided with additional layers of carbon fiber located between the outer wooden plates and the main reinforcing layers of carbon fiber, while the carbon fibers The adjacent reinforcing layers are mutually perpendicular. 2. A racket according to claim 1, characterized in that the carbon fibers in the reinforcing layers adjacent to the core are arranged perpendicular to the direction of the wood fibers. 3. A racket according to claim 1, characterized in that the thickness of the carbon fibers in all layers is the same and is 0.1-0.2 mm. 4. A method of manufacturing a table tennis racket, comprising forming reinforcing layers of carbon fibers, applying an adhesive composition to the core and outer wooden layers, placed between reinforcing layers and subsequent molding, characterized in that, in order to improve manufacturability, reinforcing the layers are formed directly on the adhesive-coated core by successively laying the carbon fibers in layers first across the core fibers, and then along them and shaping them with using removable auxiliary plates with a glossy non-wettable adhesive surface. I EU L Ft.1 Fm.1 7 Fm.4 at 5.  9