Universal Joint for Slitters
(D-Type with Sliding Key Specification)

Slitters are cutting machines widely used in the paper, printing, and film industries.

The gearboxes of these machines feature two parallel shafts,

and a universal joint is employed on the upper shaft.

 

Why use a joint in a slitter? Identifying the challenge

 

Because slitters require blade position adjustments based on the thickness of the workpiece (material being cut),

the shaft holding the blade must be movable vertically.

This movement inevitably results in shaft misalignment (offset and angular misalignment).

To solve this issue and reliably transmit power while maintaining the necessary angles,

a universal joint is essential.

Typically, a joint assembly with an integrated telescopic shaft is used to accommodate such misalignment.

However, this creates a new problem: the machine becomes larger overall.

Since a joint assembly with a shaft follows a [Joint + Intermediate Shaft + Joint] structure,

the total length inevitably becomes quite long.

The customer wanted to save as much space as possible to fit the equipment into the limited space available in the factory.

 

What is the ideal joint that combines space-saving design with telescopic functionality?

 

The solution that addressed both of these challenges simultaneously

was Miyoshi Kikai’s compact double universal joint, the “D-Type (D-30).”

First, let’s look at the challenge of saving space.

The D-Type is designed for high precision and compactness, allowing for a significant reduction in total length compared to standard joints.

A comparison of the dimensions makes the difference immediately apparent. Shaft-equipped type (B-30PS): Minimum manufactured length 458 mm

Standard double-joint type (BD-30): Total length 275 mm

High-precision compact double-joint type (D-30): Total length 182 mm

This design achieves significant space savings: 93 mm less than the BD-30 and a remarkable 276 mm less than the B-30PS.

Next is the second challenge: the “telescopic function.”

The D-type joint does not inherently possess telescopic capabilities.

To address this, we machined a keyway into the shaft bore and modified the design to a “sliding key” specification.

This enables smooth sliding movement during vertical travel while simultaneously transmitting power.

D-30 Product Page:miyoshi kikai | Products | Standard Type Universal Joint

 

Thinking outside the box leads to the optimal solution.

 

This mechanism was born from free, unconventional thinking,

breaking free from the fixed notion that “misalignment or angular deviation requires a shaft-equipped joint.”

It solves three challenges—accommodating misalignment/angles, compactness, and telescopic functionality—with just a single joint.

It is truly the ideal universal joint for resolving the challenges faced by slitter machines.