Chapter 6 Design of Keys, Splines and Pins

1. Chapter 6 Design of Keys, Splines and Pins Key terms: • Keys • Splines • Keyway, keyseat • Hub • Crush • Pin

2. 6.1 Key Joints • 1. Basic Concept A key is a fastening inserted into the keyway of two mating parts, it is used to transmit torque from a shaft to a hub or vice versa.

3. 2. Types of Keys • Straight keys • Woodruff keys • Taper keys • Splines

4. clearance 3. Straight Key Joints • 1) Principles

5. 2) Types a. Plain flat keys 普通平键 (fixed joints) C Key with one square and one rounded end B Key with square ends A Key with rounded ends

6. b. guided keys (sliding joints)

7. c. feather key joints (sliding joints)

8. 4.Woodruff Key Joints Greater depth of the key seat in the shaft.

9. 5. Taper Key Joints Gib-head taper key

10. Tangent Double-taper Key Joints

11. 2)Crushed Strength Condition 6. Strength Calculation of Straight Key Joints 1)Failure Modes: crush, wear, snip T——torque d——diameter of shaft h——thickness of the key l——working length of the key [p]——allowable crush stress

12. h b L 3) Steps for Selecting Straight Keys • a. According to the diameter of shaft, get section size b  h; • b. Select proper key length L in key length series; • c. Check the Strength Calculation (if necessary);

13. 4) Double-Keys Arrangement

14. Splines are classified as: Parallel-sided splines Involute splines 6.2 Splines Joints • Splines can be dealt as multiple keys which are integral with the shaft.

16. Advantages:1) Greater carrying capacity; 2) Greater fatigue strength of a spline shaft; 3) More accurately centered and guided. Disadvantages: Requirements for special equipments and tools, which increase the manufacturing costs.

17. 6.3 Pin Joints Pin for joining Cylindrical pin Taper pin safety pin

18. Key Standards

19. The endThanks!