This part of GB/T 9239 specifies one convention for balancing the individual components (shaft and fitments) of a keyed rotor assembly. This provides compatibility of all balanced components so that when they have been assembled the overall balance tolerance and/or vibration limit for the rotor assembly is met.
This part specifies that half-keys be used when balancing the individual components of a keyed rotor assembly. It also specifies a marking of the components balanced in accordance with the key convention used.
This part applies to rotors balanced in a balancing machine, in their own bearings or in situ. The key convention can also be applied when measuring the residual unbalance and/or vibration of rotors with keyways, but to which fitments have not yet been assembled.
In addition to applying to keys of constant rectangular or square cross-section mounted parallel to the shaft centreline, this part also applies to keys mounted on tapered shaft surfaces, to woodruff, taper, dowel and other special keys. The principle of the half-key convention is applied as is appropriate to the particular shape and location of the special key.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including having amendments) applies to this document.
ISO 1925 Mechanical vibration - Balancing - Vocabulary )
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1925 apply.
4 Half-key convention
This part specifies that the half-key convention be followed. According to this convention, a half-key shall be used in the keyway of the shaft having one keyway while balancing the shaft without the fitment. A complementary half-key shall be used while balancing the corresponding fitment on a balancing mandrel, provided the mandrel has no keyways. If the mandrel has keyways, the methods described in A.1.3 shall be followed. If at one cross-section, shaft and fitment each have two keyways the methods described in A.1.4 shall be followed. The axial location of the centre of gravity of the half-key should be the same as that of the full key in the final assembly.
Note: Table 1 shows examples of various types of shaft keyways and full keys of constant rectangular or square cross-section.
Practical considerations for making and usage of half-keys are given in Annex B. A contoured half-key set is shown in Figure 1.
The use of the half-key convention provides a uniform method for balancing shafts and fitments joined together by keys. It eliminates balance errors and therefore unnecessary residual unbalance and/or vibration which can be caused by the use of different key conventions, and avoids the creation of an internal bending moment in the assembly (as would be caused by the use of full keys during balancing of the shaft). For more information on the differences between the key conventions, see Annex C.
GB/T 9239.32-2017 The following standards are cited：
GB/T 9239.32-2017 Cited by the following standards：
