Free	The spring is not loaded (index 0).
Preloaded	Smallest working load is applied to the spring index (index 1).
Fully loaded	Maximum working load is applied to the spring (index 8).
Limit	The spring is deflected to the solid length (index 9).

The Calculation tab has: design and check. During spring design, the wire diameter, number of coils, and spring free length L0 are designed for a specific load, assembly dimensions (j1, j8, jH) or for the spring diameter and material. In the check mode, assembly dimensions or spring loads are calculated for the specific spring.

In the Torsion Spring Component Generator:

On the Design tab, set parameters for a torsion spring design such as the wire diameter or arm type.
On the Calculation tab, set parameters for calculation of a torsion spring, loads or spring materials for example.

TipThe calculation procedure is described in the Engineer's Handbook for both modes and for the calculation in metric and English units. You also find other instructions for designing torsion springs in it.

Procedures

Design torsion springs

Insert torsion springs

On the ribbon, click Design tab Spring panel Torsion.
In the Design tab, select the options for designed torsion spring.
Switch to the Calculation tab and enter the calculation values. For example, select the type of strength calculation and set the loads and spring material.
Note: Click More in the right lower corner to display additional options for spring design.
Click Calculate to perform the Calculation.
Calculation results are displayed in the Results area. The inputs that fail the calculation are displayed in red (their value does not correspond with other inserted values or calculation criteria). The description of calculation results is displayed in the Summary of Messages area which is displayed after clicking the chevron in the right lower part of the Design and Calculation tabs.
Click OK to insert a spring to the Autodesk Inventor assembly.

TipClick

Results to display the HTML report.

Edit springs using Torsion Spring Generator

Open the Autodesk Inventor assembly with the already inserted Design Accelerator torsion spring.
Select the torsion spring, right-click to display the context menu and select the Edit Using Design Accelerator command.
Edit the torsion spring. You can change the type of the load, change the spring material, or change the size of the spring. If you changed calculation values, click Calculate to see if strength check was OK. Calculation results are displayed in the Results area. The inputs that fail the calculation are displayed in red (their value doesn't correspond with other inserted values or calculation criteria). Reports of the calculation are displayed in the Summary of Messages area.
Click OK.

References

Torsion Spring Component Generator - Design tab

Sets parameters for design of a torsion spring.

Access:

Ribbon: Design tab

Spring panel

Torsion

Spring Reference Image

Click to display an image with the basic spring dimensions.

The image updates when you change the arm type, direction of spring load, or coil direction.

Model

Min. Load angle between arms is set based on the minimum deflection of working arm.
Working Load angle between arms is set based on the maximum deflection of working arm.
Max. Load angle between arms is calculated based on working force.
Custom angle between arms is set by a user.
Angle Between Spring Arms	This option is enabled only if you select the Custom option in the Model drop-down list. If you select other type of load, this value is calculated when you click Calculate.
Coil Direction	Select the direction of the coil, left or right.

Spring Wire

Enter or measure the wire diameter value.

Spring Diameter

Use the drop-down list to specify which spring dimensions are the inputs for the calculation, and which dimensions is calculated.

Outer - Mean and inner spring diameters are calculated for the specified wire diameter and outside spring diameter.

Median - Inner and outside spring diameters are calculated for the specified wire diameter and mean spring diameter.

Inner - Mean and outside spring diameters are calculated for the specified wire diameter and inside spring diameter.

NoteAccording to this selection the name of the following edit field changes to Inside Diameter, Mean Diameter, or Outside Diameter.

Start Arm, End Arm

Use the drop-down menu to select the type of the spring arm. According to your selection, Bending Radius edit field is either enabled or disabled in the lower part of the area.

Arm Type	Tangential Straight working and supporting spring arms are straight torsion arms.
	Radial External working spring arm is a straight torsion arm, and the supporting arm is a straight hook arm bent.
	Axial Straight working spring arm is a straight hook arm bent, and the supporting arm is a straight torsion arm.
	Radial Internal working spring arm is a straight torsion arm, and the supporting arm is a straight hook arm bent.
Arm Length	Enter or measure the arm length.
Bending Radius	This option is disabled if you select Tangential Straight type of arm from the drop-down list in this area.

Spring Length

Use this section to define which parameters are entered and which are calculated.

Length Inputs	L₀, t n	Calculates the number of spring coils for the specified wire diameter, length of unloaded spring and shape and size of spring hook.
	t, n L₀	Calculates the length of unloaded spring for the specified wire diameter, number of coils and shape and size of spring hook.
Loose Spring Length	Enter or measure the loose spring length value. This option is available only if L₀, t n is selected in the Length Inputs drop-down list.
Close Pitch	Specify the coil pitch. Clear the check box, and click next to the edit field to open the Pitch between Spring Coils dialog box where you can specify the value of the pitch between spring coils. Selected value transfers to the Design tab when you click OK. When the edit field is enabled, the value is calculated when you click Calculate.
Active Coils Number	Specify the spring number of active coils.

Results

To display the Results area on the right side of the Calculation and Design tabs, double-click the double line on the right or click the chevron.

Results area displays appropriate results which need to be calculated to get all proper dimensions of spring. Click Calculate to display the values. The units of the results values can be changed. Double-click the specified value you want to change.

Following output parameters are displayed in the Results pane:

Angle between Arms for the Free State (a₀)
Spring Index (c)
Mean Spring Diameter (D)
Outside Spring Diameter (D₁)
Inside Spring Diameter (D₂)

NoteFor further description of the calculated parameters in metric or English units, see Engineer's Handbook.

Summary of Messages

Displays the reports about calculation. To open the Summary of Messages area at the bottom of the Calculation and Design tabs, double-click the double line at the bottom of tabs or click the chevron at the bottom of the tabs.

Toolbar Commands

Torsion Spring Component Generator - Calculation tab

Sets parameters for calculation of a torsion spring.

Access:

Ribbon: Design tab

Spring panel

Torsion

and click the Calculation tab.

Spring Strength Calculation

Torsion Spring Design	Designs dimensions of the torsion spring for the specified spring load.
Spring Check Calculation	Calculates the assembly dimensions and a tension spring strength check for the specified load and spring dimensions.
Work Forces Calculation	Calculates the forces induced by the torsion spring of the specified dimensions.

Calculation Option

Select the options for spring calculation.

Direction of Spring Load	A Load Coils the Spring	The spring is loaded in the direction of coils winding.
	A Load Uncoils the Spring	The spring is loaded in the direction of coils unwinding.
Design Type	NoteThis option is available only if you select Torsion Spring Design in the Spring Strength Calculation area.
	F₈, Assembly Dimensions d, n, D, F₁	Designs suitable wire diameter, number of coils, spring diameter, and minimum load for the specified maximum load and assembly dimensions of the spring.
	F, jh d, n, D, Deflections	Designs suitable wire diameter, number of coils, spring diameter, and angular deflections of working arm for the specified load and angle of working stroke.
	F, D d, n, Assembly Dimensions	Designs suitable wire diameter, number of coils and assembly dimensions are designed for the specified load and torsion spring diameter.
	F₈, D, j*h d, n, F1, Deflections	Designs suitable wire diameter, number of coils, angular deflections of working arm and minimum load for the specified maximum load, angle of working stroke and torsion spring diameter.
Method of Stress curvature correction	Use the drop-down list to select the method of stress curvature correction.
	With helical springs, the stress appearing in the spring coils at the given loading is calculated for simple torsion. Additional bending stress appears in the coil due to its rounding. Therefore, the stress is corrected in the calculation using a correction coefficient. As several different coefficients are commonly used, choose from the list the correction coefficient which meets your local usage or recommendations of standards.
	NoteIn view of strength check of a spring exposed to static loading, using the correction coefficient from Gahner gives the best results.
	Hint: With springs exposed to static loading, corrections are not executed.

Loads

This option is not available if you select Work Forces Calculation in the Spring Strength Calculation area.

Calculate the Moments	The spring working forces are calculated for the specified bending moments and the arm length.
Calculate the Forces	The bending moments are calculated for the specified spring working forces and the arm length.

Spring Mounting

Check the box to enable to input or measure values.

Perform the dimension check of spring rod and housing.

Dimensions

Enter or measure the spring dimensions.

Spring Coils

Rounding of Coil Number	Set the value for rounding the coil number value.
Active Coils Number	Specify the spring number of active coils.

Spring Material

Select the spring material and its properties. Click to open the Material Database where you can select the appropriate material.

Warning: Strength parameters of material are determined empirically and reflect minimum values applicable for a group of materials. Although these values are close to the values obtained using measurement of particular materials, it is recommended in cases of final calculations to use the parameters of material according to the material sheet or specifications of the producer.

Material	Specifies material values you enter or select from the Material Database.
	If a material is selected from the Material Database, its values are inserted automatically into the following edit fields, and the edit fields are locked. To unlock the field clear the box.
Allowable Bending Stress	Enter the modulus of allowable bending stress of the spring material.
Modulus of Elasticity	Enter the modulus of elasticity of the spring material.
Density	Enter the density of the spring material.
Utilization of Material	Enter the utilization factor of the spring material. Click the arrow next to the edit field where you can set the value.
	The coefficient gives a relation between the torsion stress of a spring in the fully loaded state and the allowable torsion stress, such as u_S » t₈ / t_A. If a greater value is selected, less material is needed for spring production and the spring dimensions and the space for mounting are less, but the securing of spring stability during its function is lower, and vice versa. Therefore, this coefficient is a reciprocal value of the safety rate. For common operational conditions, the value of the utilization factor of the material is recommended to be within the u_S = 0.85 ... 0.95 range. Lower values can be used for springs working in aggressive surroundings, at high temperatures or loaded with impacts.
	The value of the utilization factor of the material is selected in a dialog box where a range of recommended values is designated.

Assembly Dimensions

j1, jh j8	Calculates the maximum angular deflection of working arm for the specified angle of working stroke and minimum angular deflection of working arm.
j8, jh j1	Calculates the minimum angular deflection of working arm for the specified angle of working stroke and maximum angular deflection of working arm.
j1, j8 jh	Calculates the angle of working stroke for the specified angular deflections of working arm.

(More)

Displays additional options for spring design. To display the More Options area, click More in the right lower corner of the Calculation tab.

Design of Working Stoke Angle
NoteThis area is available only if following two options are selected: Torsion Spring Design in the Spring Strength Calculation area, and F, D d, n, Assembly in the Design Type drop-down list.
Not Specified	Designs suitable angle of working stroke for the specified load and spring diameter.
Minimum Angle	Designs suitable angle of working stroke that is larger than the minimum allowable value for the specified load and spring diameter.
Maximum Angle	Designs suitable angle of working stroke that is smaller than the maximum allowable value for the specified load and spring diameter.
Angular Range	Designs suitable angle of working stroke that is the nearest to the required angle for the specified load and spring diameter.
Design of Spring Diameter
NoteThis area is available only if following two options are selected: Torsion Spring Design in the Spring Strength Calculation area, and F₈, Assembly Dimensions d, n, D, F₁; or F, j_h d, n, D, Deflections in the Design Type drop-down list.
Not Specified	Designs the smallest suitable spring diameter for the specified load and spring assembly dimensions.
Minimum Diameter	Designs the smallest suitable spring diameter larger than the minimum allowable value D2min for the specified load and spring assembly dimensions.
Maximum Diameter	Designs suitable spring outside diameter smaller than the maximum allowable value D1max for the specified load and spring assembly dimensions.
Diameter Range	Designs suitable spring diameter nearest to the demanded diameter D' for the specified load and spring assembly dimensions.

Results

To display the Results area on the right side of the Calculation and Design tabs, double-click the double line on the right or click the chevron.

Displays the calculated dimensions values such as spring mass or wire length. Click Calculate to display the values. The units of the results values can be changed. Double-click the specified value you want to change.

Following output parameters are displayed in the Results pane:

Results
- Min. Load Bending Stress of the Spring Material (s₁)
- Max. Load Bending Stress of the Spring Material (s₈)
- Length of Mx. Load Coiled Part (L₈)
- Spring Max. Load Inside Diameter (D₂₈)
- Stress Concentration Factor (k_f)
- Spring Rate (kj)
- Limit Test Angle Deflection of Working Arm (j_max)
- Deformation Energy (W₈)
- Wire Length (l)
- Spring Mass (m)

NoteFor further description of the calculated parameters in metric and English units, see Engineer's Handbook.

Summary of Messages

Toolbar Commands

Inventor

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Torsion Spring Component Generator

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