Extension Spring Calculator

	Customer input field
	Explanation display field
Blank	Display after calculation

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Tokai Spring industries, Inc.

STEP1. Enter the required dimensions in the yellow blanks

Dimension input field
Material
Wire diameter d		mm
Center diameter D		mm
Active coils N		Coils
Free length H (Auto calculation if blank)		mm
Spring constant Calculate automatically		N/mm

*The initial tension is calculated as 0 N.

*The calculable free length is up to 700 mm.
Please consult us if it exceeds 700 mm.

*If you need a length longer than the free length of calculation,
set the pitch It can be adjusted by opening it or lengthening the hook.

Back calculation result column
Required spring constant		N/mm
Back calculation wire diameter		mm
Back calculation center diameter		mm
Back calculation active coils		Coils

STEP2. Enter the required twist angle in the yelow blanks

Load/Static stress characteristics field
	Load P(N) input	Spring usage range		Coil shear stress(N/mm²)		Tensile stress of hook
	Load P(N) input	Height(mm)	Deflection(mm)	τ	τ₀	σ	Pass/fail
First load
Second load
Third load
Fourth load
Free state	－		－	－	－	－	－

Please check the calculation result.

Fixed basic specifications
Outer diameter	mm	Bending R	mm	Coil part Maximum using stress		N/mm²
Inner diameter	mm	Coil part contact height	mm	Hook part Maximum using stress		N/mm²
D/d	－	Hook length on one side	mm	－	－	－

Design advice on calculation result.

Regarding the shape advice	Active coils N
	Active coils N
	D/d
Regarding stress advice	Coil shear stressτ₀ (First load)
	Coil shear stressτ₀ (Second load)
	Coil shear stressτ₀ (Third load)
	Coil shear stressτ₀ (Fourth load)
	Tensile stress of hook (First load)
	Tensile stress of hook (Second load)
	Tensile stress of hook (Third load)
	Tensile stress of hook (Fourth load)

This comment is for reference only.
Even if a comment to correct the entered value is displayed,
I may be able to do a special and optimal design for you.
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