Screw cap

Abstract

A screw cap of plastic material has a cap disk and an outer cap rim located adjacent at a right angle to a circumference of the cap disk. The cap rim has an internal thread for closing a filling and / or removal socket of a container for transporting and storing liquid, and a central bung socket arranged retracted in the cap disk, wherein the bung socket has an internal thread for screwing in a bung plug. The bung plug has a cylindrical threaded sleeve with an external thread for screwing in a threaded bore of the bung plug of the cap, and a sealing end provided with a conical multiple seal of sealing rings which, when the bung plug is screwed in, are pressed against a conical inner sealing surface of a sealing projection located adjacent the threaded bore of the bung socket of the screw cap.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a screw cap of plastic material with a cap disk and an outer cap rim located adjacent at a right angle to the circumference of the cap disk, wherein the cap rim has an internal thread for closing a filling and / or removal socket of a container for transporting and storing liquids, and with a central bung socket arranged retracted in the cap disk, wherein the bung socket has an internal thread for screwing in a bung plug.[0003]2. Description of the Related Art[0004]The screw cap known from EP 0 650 446 B1 of the above-described type for closing the filling socket of a bung drum or the internal plastic container of a pallet container with an outer casing of grate rods or sheet metal have the disadvantage that the sealing ring for sealing the bung plug in the bung socket of the screw cap over time does not ensure the tightness of the bung plug closure due to aging phenomena of the material o...

AI Technical Summary

Benefits of technology

[0005]It is the object of the present invention to improve the screw cap of the above-described type with respect to an improved tightness of the bung plug closure, a less expensive manufacture, and lowering of the operating costs of the liquid containers equipped with the screw cap which are used as reusable containers.

[0006]In accordance with the present invention, a screw cap with a bung socket which is equipped with a bung socket closure has the following advantages.

[0007]By providing the plastic bung plug for closing the bung socket of the screw cap with a conical multiple seal in the form of spaced-apart sealing rings integrally injection molded with the bung socket, wherein the multiple seal is pressed against a conical inner sealing surface of the bung socket when the bung plug is screwed in, an optimum tightness of the bung socket closure is facilitated. In containers with internal pressure, the tightness of the bung plug closure for the bung socket of the screw cap is further improved by additionally increasing the contact pressure of the sealing rings of the conical multiple seal of the plug relative to the conical inner sealing surface of the bung socket caused by screwing in the bung socket as a result of the internal pressure of the container acting on the inner wall of the sealing end of the threaded sleeve of the bung plug provided with the multiple seal. By omitting a sealing ring, which would have to be regularly replaced, the manufacturing costs compared to known screw caps with bung sockets which is closed by means of a bung plug with sealing ring, as well as the maintenance costs for liquid containers which are equipped with a screw cap with the novel bung plug for the bung socket of the cap and which are used as multiple-use containers can be significantly lowered.

Problems solved by technology

The screw cap known from EP 0 650 446 B1 of the above-described type for closing the filling socket of a bung drum or the internal plastic container of a pallet container with an outer casing of grate rods or sheet metal have the disadvantage that the sealing ring for sealing the bung plug in the bung socket of the screw cap over time does not ensure the tightness of the bung plug closure due to aging phenomena of the material of which the sealing ring is manufactured, particularly in containers for transporting and storing chemical liquids, so that the sealing ring must be replaced regularly.

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