Capacitor Case Molding with Low-Temperature Metal Mold
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the manufacturing of case-molded capacitors, the generation of burrs during the molding process leads to the need for abrasive blasting, which can roughen terminal units, increase electric resistance, and compromise connection accuracy and strength, especially when integrated with external terminals.
Innovation Solution
The method involves forming a case with a metal mold heated to a temperature below the glass transition temperature of the thermoplastic resin, preventing burr formation and eliminating the need for burr removal processes, thereby maintaining the integrity and accuracy of terminal connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the metal mold is heated to a high temperature during molding, then the resin flows easily and fills the mold cavity completely, but burrs are generated on the case surface
Solution Approach 1:
The patent changes the temperature parameter of the metal mold from conventional high temperature to a specific low temperature range (0°C to 50°C, preferably 10°C to 30°C). This parameter change prevents burr generation on the case surface while still achieving complete mold cavity filling through optimized injection parameters
Solution Approach 2:
The patent applies preliminary cooling to the metal mold before injection, maintaining it at a low temperature (0°C to 50°C) in advance. This preliminary action creates a temperature differential that prevents resin from adhering to the mold surface and forming burrs, while the resin is injected in a controlled manner to ensure complete filling
2Manufacturing precision
If abrasive blasting is used to remove burrs, then the case surface is cleaned, but the terminal unit surface becomes rough and electric resistance increases
Solution Approach 1:
The patent converts the potential harm of resin adhesion to burr formation into a benefit by using low temperature molding. The cold mold surface prevents resin from sticking and forming burrs in the first place, eliminating the need for abrasive blasting and protecting the terminal unit surface from damage
Solution Approach 2:
The patent applies preliminary anti-action by cooling the mold surface before injection to prevent burr formation. This preventive measure counteracts the tendency of hot resin to adhere to the mold surface and form burrs, thereby protecting the terminal unit from subsequent abrasive blasting damage
3Productivity
If the metal mold temperature is increased to improve resin flow, then filling is improved, but burr generation increases requiring additional removal processes
Solution Approach 1:
The patent changes the mold temperature parameter from high to low (0°C to 50°C) and compensates by optimizing injection parameters such as injection pressure and injection speed. This maintains productive molding cycle efficiency while preventing burr generation on the case surface
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
This approach effectively prevents burr generation, maintains surface smoothness and connection reliability, and ensures proper fracture strength of the case, avoiding issues related to electric resistance and terminal deformation.
Implementation Method 1
heating a metal mold to a temperature less than or equal to a glass transition temperature of a thermoplastic resin that is a material for the case
Implementation Method 2
injecting the thermoplastic resin in a molten state into the mold part of the metal mold
Data Source
AI summary
A method for manufacturing a capacitor includes a step of forming a case integrated with a terminal unit designed to be connected with an external terminal, and a step of housing a capacitor element in the case so that the terminal unit is electrically connected to the capacitor element. The step of forming the case includes heating a metal mold to a temperature less than or equal to a glass transition temperature of a thermoplastic resin that is a material for the case. The metal mold internally has a mold part that is a hollow part having a shape of the case. And the step of forming the case further includes, after the heating of the metal mold and inserting the terminal unit into the mold part, injecting the thermoplastic resin in a molten state into the mold part of the metal mold.