GB/T 17855-2017 PDF English
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Calculation of load capacity of spline
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GB/T 17855-2017: PDF in English (GBT 17855-2017) GB/T 17855-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 21.120.30
J 18
Replacing GB/T 17855-1999
Calculation of load capacity of spline
ISSUED ON: SEPTEMBER 07, 2017
IMPLEMENTED ON: APRIL 01, 2018
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and codes ... 4
4 Load analysis and calculation ... 7
5 Factor ... 13
6 Calculation of load-bearing capacity ... 15
7 Examples ... 19
Calculation of load capacity of spline
1 Scope
This standard specifies the calculation method for the load capacity of
cylindrical straight tooth involute splines and cylindrical rectangular tooth
splines (hereinafter referred to as splines).
This standard applies to splines manufactured in accordance with GB/T 1144
and GB/T 3478.1. Other types of splines may refer to this standard.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 1144 Straight-sided spline - Dimensions, tolerances and verification
GB/T 3478.1-2008 Straight cylindrical involute splines - Metric module side
fit - Part 1: Generalities
3 Terms and codes
Terms and codes are as shown in Table 1.
Rectangular spline:
4.2.4 Calculation of shaft load F and bending moment Mb:
The shaft load F and bending moment Mb of the spline pair shall be calculated
after force analysis according to the specific transmission structure.
5 Factor
5.1 Use factor K1
The use factor K1 is mainly a factor that considers the influence of power
overload caused by external factors of the transmission system. The impact of
this overload depends on factors such as the characteristics of the prime mover
(input) and the working machine (output), the mass ratio, the mating nature and
accuracy of the spline pair, the operating status, etc.
The coefficient can be obtained by precise measurement, or it can be
determined after analyzing the whole system. When the above method cannot
be realized, it can refer to Table 2 for values.
Table 2 -- Use factor K1
5.2 Tooth side clearance factor K2
When the stressing state of the spline pair is as shown in Figure 4, the load on
the teeth of the involute spline or rectangular spline depends on the elastic
deformation of the key teeth; it also depends on the size of the side clearance
of spline pair. Under the action of the shaft load, as the backlash changes (half
of the circumferential gap increases, the other half of the circumferential gap
decreases), there will be a relative displacement e0 between the two axes of
the inner spline and the outer spline, as shown in Figures 4 and 9. The
magnitude of the displacement e0 is related to factors such as the size of the
backlash (clearance) of the spline and the level of manufacturing accuracy.
After the displacement occurs, the load is distributed on fewer key teeth (the
self-centering effect is lost for the involute spline), which affects the load-
bearing capacity of the spline. The side clearance factor K2 considers of this
impact, usually K2 = 1.1 ~ 3.0.
When the shaft load is small and the accuracy of the spline pair is high, it may
take K2 = 1.1 ~ 1.5; when the shaft load is large and the accuracy of the spline
pair is low, it may take K2 = 2.0 ~ 3.0; when the shaft load is zero and only
bearing the rotational moment (see Figure 2), K2 = 1.0.
5.3 Distribution factor K3
When the two axes of the inner spline and the outer spline of the spline pair are
coaxial, the theoretical backlash (single tooth backlash) of the spline pair is
different due to the influence of cumulative error of the tooth pitch (indexing
error); the load on each key tooth is also different.
The distribution factor K3 considers this influence. For the spline pair before
running-in, when the accuracy is high (the precision rectangular spline
according to the GB/T 1144 standard or the accuracy level according to the
GB/T 3478.1-2008 standard is level 5 or higher), K3 = 1.1 ~ 1.2. When the
accuracy is low (the general use rectangular splines according to the GB/T 1144
standard or the accuracy level according to the GB/T 3478.1-2008 standard is
lower than level 5), K3 = 1.3 ~ 1.6. For the spline pair after running-in, when
each key tooth is involved in the work, and the load is basically the same, take
K3 = 1.0.
5.4 Axial eccentric load factor K4
Due to the tooth orientation error produced during the manufacture of the spline
pair and the concentricity error after installation, as well as the torsional
deformation after being loaded, the load on each key tooth along the axial
direction is uneven. The axial eccentric load factor K4 is used to consider this.
Its value can be selected from Table 3.
For the spline pair after running-in, when the axial load distribution of each key
tooth is basically the same, it takes K4 = 1.0.
When the accuracy of the spline is high and the indexing circle diameter D or
the average circle diameter dm is small, the axial eccentric load factor K4 in
Table 3 shall be the smaller value, and vice versa.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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