Industries & Applications

Examples of Where Our Springs Have Been used By utilizing our spring manufacturing technology that we have nurtured over the years,

we have solved a whole host of spring-related issues in various fields.

Case Medieval technology solved with modern spring technology! Significant performance improvement.

Medieval technology solved with modern spring technology! Significant performance improvement.

Client Data

Traditional product preservation group

Use Spring:Plate springs

Period:2 months

Plate spring for opening and closing movement of Karakuri doll

Examples of Tokai Spring achievements

Tokai Spring Industries possesses unique manufacturing technology based on many years of experience of delivering products to customers in the culture and arts industry. “We want to replace a spring on a device designed a long time ago, but we don’t have the drawings…” “A primitive material was used for a spring, but it’s no longer available…”
We have solved such problems with our high-quality springs containing a generous amount of our know-how.

Problems and challenges

The traditional Japanese craft “Karakuri doll” is equipped with a shutter. Its opening and closing mechanism has been made of a material called “baleen” which functioned as a spring in the past. When the mechanism broke down, we planned to fix it by replacing it with modern spring.


First, in order to realize the spring characteristics required for the spring of the opening and closing mechanism, we measured and quantified the load characteristics of the conventional baleen material. In addition, the customer required that the spring mechanism should be able to take a large amount of deflection, withstand long-term use, and was easy to maintain. Based on these requirements, we conducted spring design simulations and studied materials and spring types. As a result, we selected carbon steel as the material and plate spring as the spring type.


The designed plate spring was manufactured and used in the opening and closing mechanism of a real Karakuri doll.
As a result of the operational verification, it was confirmed that the spring functioned as conventional baleen, and the sensory characteristics were reproduced without any sense of discomfort. The spring helped to preserve a valuable traditional Japanese product.

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