Examples of Tokai Spring achievements

Tokai Spring Industries possesses unique manufacturing technology based on many years of experience of delivering products to customers who manufacture safety valves for power plants. Our springs are particularly useful for safety valves that require high-precision springs.

Problems and challenges

This is the result of consultations on dish springs from IPCR (Institute of Physical and Chemical Research). The application is a cutting-edge research project using a “light source generator” called an “undulator” that generates laser light by passing an electron beam through a powerful magnetic field in which several magnet blocks are arranged. The customer wanted to further increase the laser power by reducing the distance between the magnet blocks, which generate a strong attractive force, and by strengthening the magnetic force applied to the electron beam. In order to accomplish this task, disc springs with extremely high precision load characteristics were required. To explain the requirements for disc springs in detail, more than 10 sets of multiple disc springs were required, and the variation in spring constant among these disc springs had to be as close to zero as possible. We have decided to take on the challenge of meeting this difficult requirement by using our accumulated technical data and manufacturing know-how to achieve ultra-high precision.

Solution

In order to achieve the required load accuracy of disc springs, it is essential to have not only the technology to manufacture ultra-high precision disc springs, but also the tools, measuring instruments and measuring technologies to precisely measure and confirm the performance of the completed springs. To minimize the load variation, the disc spring has been designed using ultra-precision machining with a dimensional accuracy of 1/100mm and a special shape design that does not change the inner diameter of the disc spring even when it is compressed. In addition, we made a “spring load testing machine” that is strictly maintained and controlled, as well as customized jigs and tools that are manufactured and controlled with ultra-high precision.

Results

We were able to reduce the variation of the spring constant of the entire set of more than 10 disc springs to less than ±1% with satisfying repeatability. In addition to this result, our products were rated high by our customers when they tested the disc springs for permanent set-in fatigue after repeated use, and they finally decided to install our products in their most advanced undulators.