Technical Calculation Software
| File Name | Catalog Page | File Size | Uncompressed File Size |
|---|---|---|---|
| Linear Guides · Ball Screws Technical Calculation Software Ver.2.0 | - | 6.79 MB | 6.85MB |
Selection Example
Lead (L) Selection
Required lead is calculated based on the motor max. speed and Maximum Speed Requirement.
20mm lead or more is required.
Nut Selection
(1) Axial Load Calculation
Axial Load calculation of P.1897, 6-2 is applied.
- ・Constant Velocity Phase: Axial Load (Pb) = μWg = 0.02 x 50 x 9.8 ≈ 10 (N)
- ・Acceleration Phase: Acceleration (α) = (Vmax/t) x 10-3 = 6.67 (m/s2)
Axial Load (Pa) = Wα + μWg = 50 x 6.67 - 0.02 x 50 x 9.3 ≈ 343 (N) - ・Deceleration Phase: Axial Load (Pc) = Wα - μWg = 50 x 6.67 - 0.02 x 50 x 9.8 ≈ 324 (N)
(2) Profile Times Per 1 Cycle
The Duty Cycle Model Graph results as below.
| Motion Profile | Acceleration | Low Speed | Deceleration | Total Time |
|---|---|---|---|---|
| Time | 0.60 | 0.84 | 0.60 | 2.04 |
(3) Summary of: Axial Loads, Rotational Speeds, Motion Time per each profile.
| Motion Profile | Acceleration | Low Speed | Deceleration |
|---|---|---|---|
| Axial Direction | 343N | 10N | 324N |
| Rotational Speed | 1500min-1 | 3000min-1 | 1500min-1 |
| Time Ratio | 29.4％ | 41.2％ | 29.4％ |
(4) Calculate Average Axial Load
Calculate by using a formula on P.1897, 6-3.
(5) Calculate Average Rotational Speed
(6) Calculating Required Basic Dynamic Load Rating
(1) Calculate Actual Operation Life Hours (Lho)
The Actual Operation Life Hours which is Rest Time subtracted from the Desired Life Hours (2.04 seconds per 4.01 cycle) can be calculated as follows.
(2) Calculation for Required Basic Dynamic Load Rating
To satisfy the Actual Operation Life Hours, required Basic Dynamic Load Rating is calculated using the formula on P.1897, 6-1.
(7) Interim Selection of a Ball Screw
A BSS1520 is temporarily selected as a ball screw satisfying the Basic Dynamic Load Rating requirement of 3700N.
Confirming Accuracy
(1) Evaluation of Accuracy Grade and Axial Clearance
Based on the list “Ball Screw Lead Accuracy” on P.1893, 2.,
the Accuracy Grade C5 screw with Actual Mean Travel Error ±0.040/800~1000mm satisfies the required accuracy of ±0.1/720mm, therefore BSS1520 is suitable.
Additionally, based on the list “Axial Clearances of Ball Screws” on P.1893, 3.,
it can be confirmed that the BSS1520 with axial clearance of 0.005 or less can satisfy the repeatability requirement of ±0.01mm.
Ball Screw Selection
(1) Selecting Overall Length of the Screw Shaft
Ball Screw Length (L) = Max. Stroke + Nut Length + Extra Margin + Shaft End Lengths (both ends),
- Max. Stroke: 720mm
- Nut Length: 62mm
- Extra Margin: Lead x 1.5 = 60mm
- Shaft Ends: 72
Ball Screw Length (L) = 720 + 62 + 60 + 72 = 914mm
* Extra Margin is for over-run countermeasure, and is normally 1.5~2 times the screw lead.
Lead 20 x 1.5 x 2 (both ends) = 60
(2) Evaluating Allowable Axial Load
Since the Load Applicable Span Length 1 is 820mm, Allowable Axial Load (P) according to the formula on P.1895 “4. Allowable Axial Load” would be,
Max. Applied Axial Load is 343N which is less than 3660N and suitability is confirmed.
(3) Evaluating Allowable Rotational Speed
Since the supported span distance is 790mm, Allowable Rotational Speed according to the formula on P.1896 “5-1. Critical Speed” would be,
Max. Operational Speed of 3000min-1 is less than the Allowable Rotational Speed of 3024min-1 and the suitability is confirmed.
Additionally, the DmN Value according to the formula on P.1896 “5-2 DmN Value” is DmN = (Screw Dia. + A Value) x Max. Rotational Speed = 15.8 x 3000 = 47400 ≤ 70000, and the suitability is confirmed.
Selection Result
From the above evaluations, suitable ball screw would be BSS1520-914.
