Metallic Bung Closure with Plastic-Coated Thread
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Solution Overview
Problem
Conventional bung closures for steel drums used in storing and transporting dangerous liquids face issues with corrosion, contamination, and leakage due to wear and tear, especially when exposed to aggressive chemicals and high loads, and lack effective rust protection and fire safety features.
Innovation Solution
A composite bung closure with a metal cup-shaped base and a plastic-coated tubular ring part, where the external thread is formed within a sprayed-on plastic layer, providing enhanced rust protection and safety features, including a pressure relief mechanism in case of fire, and allowing for higher torque transmission without detaching from the metal base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal bung closure is coated with a chemical-resistant phenolic coating for corrosion protection, then corrosion resistance is improved, but the coating can be rubbed off during screwing and unscrewing, causing contamination and inadequate protection at thread abrasion points
Solution Approach 1:
The invention applies a plastic coating (such as polyethylene, polypropylene, or PVC) over the phenolic resin coating on the external thread. This composite coating system combines the chemical resistance of the phenolic layer with the abrasion resistance and flexibility of the plastic layer, preventing coating debris from contaminating the filling while maintaining adequate corrosion protection at thread contact points.
2Object-generated harmful factors
If a thin special coating is applied to the external thread to minimize dust and abrasion, then contamination is reduced, but the thin coating itself may be rubbed off
Solution Approach 1:
The dual-layer coating system combines a flexible plastic outer layer with a chemically resistant phenolic inner layer. The plastic layer absorbs mechanical abrasion during threading operations, preventing the phenolic coating from being exposed to direct mechanical wear while maintaining chemical resistance where needed.
3Reliability
If an all-plastic bung closure is used to eliminate corrosion, then rust protection is improved, but the plastic material has low torque transmission capability and the metal ring reinforcement may weaken the structure
Solution Approach 1:
The invention creates a composite bung closure with a metal base body providing structural strength and torque transmission capability, covered by a plastic coating that provides corrosion and rust protection. The metal cup-shaped base body maintains mechanical integrity under high torque loads while the plastic coating prevents corrosion, eliminating the need for weakening metal rings.
4Strength
If a metal bung closure is used for high torque transmission, then strength is improved, but corrosion and rust formation occur
Solution Approach 1:
The metal cup-shaped base body provides the necessary mechanical strength for torque transmission during screwing and unscrewing operations, while the plastic coating applied to the external surface and thread provides comprehensive corrosion and rust protection. This composite structure eliminates the need for phenolic resin coatings that are prone to abrasion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite bung closure offers improved rust protection, reduced risk of contamination, enhanced safety during fire exposure by preventing explosion, and maintains the handling and automation compatibility of existing systems, ensuring a secure and reliable sealing mechanism.
Implementation Method 1
a plastic layer 18 is applied to the outside of the ring part 16
Implementation Method 2
the plastic material of the sprayed-on plastic layer 18 with the molded thread softens at elevated temperatures
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a bung closure (10) for the gas-tight and liquid-tight closure of the bung opening of a container, in particular of a steel barrel for storing and for transporting in particular hazardous fluid contents. The bung closure (10) consists substantially of a cup-like basic body (12) made of metal and having a disc-like base (14) and an upwardly open tubular ring part (16) adjoining the same, wherein at least the outside of the ring part (16) has applied to it a plastic layer (18), in which - for the purpose of screwing the bung closure (10) into the bung opening of the steel barrel - a corresponding thread (20) is formed.