Importance

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Abstract

There is provided a hot melt applicator including (a) a nozzle opening, (b) a valve seat disposed upstream of the nozzle opening, (c) an empty chamber formed between the nozzle opening and the valve seat, (d) a valve body movable to the valve seat so that the valve seat is open or closed, and (e) a spring for biasing the valve body; and a pneumatically driven cylinder for driving the spring. The valve body is shaped to be a cone having an apex angle facing the nozzle opening, and the valve seat is formed with a tapered surface which is to make a contact with the cone. The tapered surface has an angle greater than the apex angle of the cone, and has a length of at least 1 mm. The hot melt applicator uses a pneumatically driven cylinder for driving the valve body to thereby compress the spring which in turn compresses the valve body, and thus, avoids the great resistance of hot melt with the spring used as a large capacity. By slightly changing angles of the valve body and the valve seat, the leakage which would occur when the valve is closed is prevented. By setting a length of the taper surface of the valve seat which is to make contact with the valve body to be in the range of 1 mm to 2 mm, the present invention makes it possible to prevent making of glue filament for a glue having great viscosity such as hot melt. In addition, setting a stroke of the valve body in the range of 0.3 mm to 0.5 mm ensures more effectively to prevent making of glue filament.

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First Claim