Date post: | 21-Feb-2018 |
Category: |
Documents |
Upload: | nicktaylor1 |
View: | 221 times |
Download: | 0 times |
of 53
7/24/2019 Drive Pin Analysis
1/53
Drive Pin Analysis
Nicholas Taylor
Tuesday 12 th May 2015
MEC3098
7/24/2019 Drive Pin Analysis
2/53
h l
Declaration
This Report is submitted as part of the requirements for the Degree of Mechanical
Engineering (MEng Honours) at the University of Newcastle upon Tyne and has not
been submitted for any other degree at this or any other University. It is solely the
work of Nicholas Taylor except where acknowledged in the text or the
Acknowledgements below. It describes work carried out at the University of Newcastle upon Tyne which is entirely recorded in a Project Logbook which has
been made available for examination. I am aware of the penalties for plagiarism,
fabrication and unacknowledged syndication and declare that this Report is free of
these.
Signed:
Date:
Acknowledgements
7/24/2019 Drive Pin Analysis
3/53
Abstract
A current 160mm Test Rig is utilised to evaluate contact fatigue testing using power
recirculating gear boxes. Gears are mounted on tapered shafts using a high
interference fit to transfer up to 6000 Nm of torque around the system. This poses the
risk of adding to stress from gear loading resulting in reduced gear capacity.
The project is to evaluate and analyse the use of pins to transfer the torque through
the system.
The optimum number of pins and size were found based on mechanical properties of
the chosen material. Interference fit and differing hole edge profiles were analysed to
provide the best reduction in stresses.
A gear blank was manufactured where sets of holes were drilled by plunge slot
drilling and interpolating. These methods were measured and compared for accuracy.
From this pin contact was evaluated to better understand the performance based on
hole drilling methods.
7/24/2019 Drive Pin Analysis
4/53
Table of Contents
1 Introduction ..................................................................................... 1
2 Material Specification ..................................................................... 2
3 Pin Design ....................................................................................... 4
4 Calculations ..................................................................................... 5
4.1 Initial pin calculations ............................................................... 6
4.2 Results forming initial pin choice ............................................. 8
4.3 Interference fit calculations .................................................... 10
4.4 FEA calculations validation .................................................... 11
4.4.1 Initial calculations correlation .............................................. 12
4.4.2 Interference fit calculations correlation ................................ 14
4.5 Pin separation due to bending stress ....................................... 16
4.6 Hub hole edge profile ............................................................. 17
5 D i f bl k 18
7/24/2019 Drive Pin Analysis
5/53
List of Figures
Figure 1. Gear mounting on 160 Test Rig. .................................................................. 1
Figure 2. Diagram showing differing modes of bending for pin ................................ 4
Figure 3 . Pin design specification ............................................................................... 4
Figure 4. Stress Convention showing orbiting element. ............................................. 5
Figure 5. Chart showing calculated bending, shear and maximum equivalent von
Mises stresses for varying critical angle ................................................................... 7
Figure 6 . Socket joint under transverse load with linear distribution of pressure ..... 10
Figure 7 . Visualisation of initial setup used in ANSYS. ........................................... 11
Figure 8. Coordinate systems used for analysis ........................................................ 12
Figure 9 . Gap size for s6max interference fit with force applied on pin................... 16
http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197834http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197834http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197834http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197835http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197835http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197835http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197835http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197835http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197836http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197836http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197836http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197837http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197837http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197837http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197838http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197838http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197838http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197838http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197838http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197838http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197839http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197839http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197839http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197840http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197840http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197840http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197841http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197841http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197841http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197842http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197842http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197842http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197842http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197841http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197840http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197839http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197838http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197838http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197837http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197836http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc419197835http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Report/Final%20Report%20R1.docx%23_Toc4191978347/24/2019 Drive Pin Analysis
6/53
List of Tables
Table 1. Mechanical Properties for chosen materials. ................................................. 3
Table 2. Given values for empirical calculations. ....................................................... 5
Table 3. Worksheet showing optimum Pin specification. ........................................... 9
Table 4 . Final variable specification chosen ............................................................... 9
Table 5 . Values of the fundamental deviations for shafts k to zc.............................. 10
Table 6. Values for tolerances ................................................................................... 11
Table 7. Pressure for considered interference fit ranges ........................................... 11
Table 8. Mesh element sizing for correlation iterations ............................................ 13
Table 9. Correlation results from the seven iterations within ANSYS ..................... 14
Table 10 . Table of pressure values comparing ANSYS and calculated values for
http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399970http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399970http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399970http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399971http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399971http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399971http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399972http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399972http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399972http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399973http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399973http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399973http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399973http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399972http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc419399971http://tower8/home47/b1031273/3rd%20Year/MEC3098%20Mechanical%20Engineering%20Project/Dissertation%20Folder/Report/Nicholas%20Taylor%20110312736%20Report.docx%23_Toc4193999707/24/2019 Drive Pin Analysis
7/53
1 Introduction
Within the Design Unit, a 160mm Test Rig is utilised to evaluate contact fatigue
testing using power recirculating gear boxes. As part of the design, gears are
mounted on tapered shafts as shown in Figure 1 using a high interference fit to
transfer up to 6000 Nm of torque around the system. By using such a high
interference for pull -up of the gears onto the shafts , induces internal hoop stressinto each gear. This poses the risk of adding to stress from gear loading resulting in
reduced gear capacity.
This project sets out to evaluate and design
the use of pins to transfer the required torque
around the system. By using pins, this would
allow using less pull -up when mounting the
gears on the shaft, thus reducing the hoop
stress within the gears ensuring the results
from the fatigue tests are more accurate. The
i ld b i i l f h i d i i f ill
Figure 1. Gear mounting on 160 Test Rig.
7/24/2019 Drive Pin Analysis
8/53
2 Material Specification
Ensuring the correct material is used in the manufacturing of the pins is critical to
how they will perform. Using a sensible and readily available material to match the
specification will allow optimum performance and longevity of the pins. Metals give
the required properties to work within the test rig set up.
They type of metal needs to have the ability to be surface hardened and provide ahigh hardness and yield strength. The pins actual profile will be key to optimising
performance and thus a metal with good machinability is also important.
By using CES EduPack (Granta, 2014) it allows to input parameters which narrows
down a database to show materials which match. By using the below limits within
Level 2:
Hardness: Minimum of 208 HV
Yield Strength: Minimum of 900 MPa
Youngs Modulus: Minimum of 200 GPa
M hi bili Mi i f 3 5 (1 P d d 5 E ll
7/24/2019 Drive Pin Analysis
9/53
S156 steel is a common material used in gear manufacturing in the Automotive and
Aerospace industries and has capability of nitride hardening.
The chosen material for the hub was 15NiCr13 (Also known as En36A) the
mechanical properties were attained from Bhler Uddeholm (En36A Case hardening
steel datasheet, 2015).
The mechanical properties for the materials are detailed below in Table 1.
Table 1. Mechanical Properties for chosen materials.
Mechanical properties34CrNiMo6 15NiMoCr13
S156 CAPi(En24) (En36)
R e min - Yield Strength (MPa) 1000 785 1030
R m - Tensile Strength (MPa) 1400 1280 1520
A - Elongation at fracture (%) 9 8 11
Z - Reduction in cross section at
f (%)40 35 40
7/24/2019 Drive Pin Analysis
10/53
3 Pin Design
The design of the pin to be used is critical to
successful operation of the Test Rig. The pin
has to have a sufficient stiffness and strength
to withstand the stresses involved, but also
the ductility to yield elastically to ensure allthe pins contact and share the load.
In a real world application, it would be extremely difficult to ensure all the variability
was controlled to an extent to ensure each pin shared the load equally. A good pin
design must incorporate sufficient flexibility to account for tolerances in
manufacturing of the respective parts.
Usually the simplest of designs is the best but not always and this case is one. Having
a simple cylindrical pin of the required length and diameter is a nice simple solution,
but actually adds complexity to the design. A cylindrical pin will have a double point
of bending as shown in Figure 2 and would result in much more complex contact
resulting in complicated calculations and analysis.
Figure 2. Diagram showing differing modes of bending for pin
7/24/2019 Drive Pin Analysis
11/53
4 Calculations
The specification for the design concepts were derived from empirical calculation
largely based on formulae working towards calculating the von Mises mean stress for
the pins (American National Standards Institution/ American Gear Manufacturers
Association, 2008).
Initial assumptions made; there is no torque on the pin; there is no axial force andthere is no hoops stress. The pins will only undergo bending and shear forces during
normal operation. The shafts will not induce any alternating stress through
misalignment and vibration. Lastly the pins will be an idealised solid cylinder for
purposes of the calculations.
In Table 2 are the given values from the project brief used for the calculations.
Table 2. Given values for empirical calculations.
Property Value Unit
Torque acting on gears 6000 Nm
7/24/2019 Drive Pin Analysis
12/53
4.1 Initial pin calculations
To find the bending stress:
=32 (1)
where F is the tangential force, l is the bending arm length, d she is the outer pin
diameter and N is the number of pins.
To find the shear stress:
=4 1+21+
(2)
where V is the transverse shear force and where is the Poissons ratio of
34CrNiMo6.
As this load case represents a simplified case then the von Mises stress has to be
l d f d ff l f f d h h l l
7/24/2019 Drive Pin Analysis
13/53
In finding the critical angle, arbitrary values for, the number of pins, pin diameter
and the bending arm length were chosen to allow calculations to be made to find the
stresses. From these, the maximum equivalent von Mises stress can be found.
Arbitrary values used:
Number of pins: 4, Pin diameter: 15mm and Bending Arm length: 15mm
From Figure 5 it can be shown that the bending stress is maximum at = 0 and the
shear stress is maximum at when = . As the bending stress is by far the dominant
stress, then the maximum equivalent v on Mises stress occurs when = 0.
7/24/2019 Drive Pin Analysis
14/53
This will give a deflection based on each pin sharing the load equally. To find the
deflection, the number of pins N was removed from equation (7).
Finally a safety factor was considered. As the pins are not a critical element within
the 160 Test Rig, a relatively low value of 1.5 is used.
To find the safety factor:
= (8)
where y is the allowable yield strength of 34CrNiMo6.
The standards details the calculation of the allowable yield strength as
=0.94500 12500 (9)
7/24/2019 Drive Pin Analysis
15/53
Individual columns for each respective stress, pin deflection and safety factor were
created for each pin diameter value to easily evaluate differing variable
combinations.
Table 3. Worksheet showing optimum Pin specification.
Torque (Nm) 6000 Calculation Constant for Shear Stress 1.23
Tangential force (N) 112150 Young's Modulus (GPa) 209
No of Pins 6 In X Condition with H Bmin 341Allowable stress (MPa) 1019
Bending arm length (mm) 12
PinDiameter(mm)
BendingStress(MPa)
ShearStress(MPa)
Deflectionsharedover pinsequally(m)
Deflectionfor 1 pin(m)
MaxEquivalentStress(MPa)
SafetyFactor
8 4462 458 256 1537 4462 0.23
9 3134 362 160 960 3134 0.33
10 2285 293 105 630 2285 0.45
11 1717 242 72 430 1717 0.59
12 1322 203 51 304 1322 0.77
13 1040 173 37 220 1040 0.98
7/24/2019 Drive Pin Analysis
16/53
4.3 Interference fit calculations
As the pins will be interference fit into the hub, calculations needed to be made to
evaluate which fit would needed due the transverse loading of the pins.
The pressure distribution as shown in Figure
6 where Dubbel (1994, p. F29) noted that for
pressure p b
This equated to a pressure of 1.35 GPa.
To calculate the interference fit needed to match the calculated pressure:
= 2( ) (12)
= +26 (11)
Figure 6 . Socket joint under transverse loadwith linear distribution of pressure
7/24/2019 Drive Pin Analysis
17/53
As can be seen in the table, the largest interference fit is for a zc tolerance which
would give +150 m.
In choosing an interference fit, part of the consideration has to be, what fit can be
sensibly achieved. With the pin diameter
only being 15mm, using a very high fit
such as zc tolerance would need
heating/cooling of parts. This endangers
deforming the pin which would be critically
damaging to the project. With this in mind,
a choice of either a p6 or s6 interference fit
would be investigated with values as shown in Table 6.
By rearranging equation (12), it was found
that pressures for the tolerances are as
shown in Table 7.
FEA software would be used to model the
four interference fits to view how the
Table 6. Values for tolerances
Table 7. Pressure for considered interferencefit ranges
7/24/2019 Drive Pin Analysis
18/53
A bonded contact was set between the hole in the bottom block and the pin. Whereas,
a frictional contact was used for the interaction of the pin and the hole in the top
block.
Fixed and Frictionless support constraints were used to limit the degrees of freedom
on the blocks. A remote displacement constraint was used on the bottom of the pin to
restrict rotation.
Mesh settings were input to concentrate refinement in the area of bending on the pin.
An overall size was added in the main mesh settings. Two Sphere of Influence were
centred on a created Coordinate Sphere of Influence system as shown in Figure 8.
7/24/2019 Drive Pin Analysis
19/53
These values acted as the midpoint of the iterations. The element sizes were factored
by h=1.5 in both increasing and decreasing the mesh sizing. The actual mesh sizes
used are detailed in Table 8.
Correlation was deemed to have occurred when the maximum Equivalent Stress as
shown in ANSYS was within 1% of the calculated value.
Table 8. Mesh element sizing for correlation iterations
Iteration1 (mm)
Iteration2 (mm)
Iteration3 (mm)
Iteration4 (mm)
Iteration5 (mm)
Iteration6 (mm)
Final(mm)
Main Mesh 10.13 6.75 4.50 3.00 2.00 1.33 0.89
Sphere ofInfluence 1 10.13 6.75 4.50 3.00 2.00 1.33 0.89
Sphere ofInfluence 2 20.25 13.50 9.00 6.00 4.00 2.67 1.78Face Mesh 2.53 1.69 1.13 0.75 0.50 0.33 0.22
The calculated stress was 676.95 MPa for parameters of 6 pins sharing the load
equally with a pin size of 15mm.
7/24/2019 Drive Pin Analysis
20/53
Table 9. Correlation results from the seven iterations within ANSYS
PIN Mesh Iteration Max EquivalentStress (MPa)% error with
previous mesh% error withCalculatedvalue
Iteration 1 629.57 -7.53
Iteration 2 649.78 +3.11 -4.18
Iteration 3 658.92 +1.39 -2.74
Iteration 4 665.35 +0.97 -1.74
Iteration 5 669.20 +0.58 -1.16
Iteration 6 688.79 +2.84 +1.72
Final 681.67 -1.04 +0.69
With an allowable stress calculated as 1019 MPa, the ANSYS result would equate to
a safety factor of 1.495 which is slightly below the 1.5 limit set previously.
4.4.2 Interference fit calculations correlation
7/24/2019 Drive Pin Analysis
21/53
The interference fit was modelled by applying a Pinball Radius to the outer edge of
the pin circumference. The size of the radius was slightly greater than the tolerance
value for each pin size. The Contact Detection Method was set to Nodal -Projected
Normal from Contact. T his minimised contact pressure spikes at the nodes if a mesh
that is adequately discretised the mesh is used on either side of the contact.
An overall mesh size was used to ensure good discretisation across both components
using sizings of 3mm, 2mm, 1.33mm and 0.89mm again , using an element step
factor of h=1.5.
In formulating the results, both the two tolerance sizes looking at each of the 4 mesh
sizes detailed above. In viewing the pressures, a Contact Tool was added to the
results tab of ANSYS. The probe tool was utilised at 7 equidistant points around the
circumference of the pin from 0 to 180. The mean of the 7 values was compared
with the calculated values.
Correlation was set to when the error between ANSYS and the calculated value was
below 3% and the range of each of the 7 probed values was under 5 MPa.
7/24/2019 Drive Pin Analysis
22/53
In conclusion, for both the pin size and interference calculations, correlation between
the ANSYS equivalent stress and the calculated values were both found using the
same overall mesh size of 0.89mm producing an acceptable error. The set up and
mesh sizing would be suitable to use in modelling and analysis of a final model
which would be derived from measurements of the manufactured gear blank.
4.5 Pin separation due to bending stress
As the force is applied to the pins, bending
occurs. The onset of this bending is below the
plane of the side wall of the hub. Due to this, a
gap opens between the edge of the hole in the
hub and the pin exterior wall as detailed in
Section 4.3.
An interference fit will reduce the gap distance.
Whilst evaluating the pressure correlation within
ANSYS, gap measurements were also taken for
each of the four fits modelled.
Figure 9 . Gap size for s6max interference fitwith force applied on pin
7/24/2019 Drive Pin Analysis
23/53
4.6 Hub hole edge profile
As each pin undergoes bending, the subsequent force in the pin is reacted by the
respective side wall of the hole in the hub. This produces high localised stresses with
the hub.
In trying to manage this stress,
differing edge profiles were
analysed to reduce the stress
concentration factor at the opening
of each hole.
Each profile would be evaluated for
max equivalent stress as in Figure
10 and the number of elements
above the yield stress of 785MPa as
shown in Figure 11 which was
graded between 1 and 10 for performance.
Figure 10 . Stress distribution for Gear profile + chamfer
Figure 11. Elements above the yield stress of 785 MPa for gear
7/24/2019 Drive Pin Analysis
24/53
5 Design of gear blank
The design of the gear blank had to closely match the specification of the actual
gears used in the 160 Test Rig. By using the specification in Figure 12 a design was
created for the blank represented in Figure 13.
Figure 12. Actual 160 Test rig gear specification. Figure 13. Gear blank design specification
7/24/2019 Drive Pin Analysis
25/53
6 Manufacture of gear blank
The gear blank was initially turned
using a Colchester Mascot 1600 to form
the approximate shape of the gear blank
without the holes. It was then machined
finished using a 5-axis CNC machine
(Hurco VMX60SR) where the hole sets
were drilled. To allow machining of the
holes a mandrel was designed which
would hold the gear blank rigidly on the
CNC Machine bed. Figure 15 details the
setup of the Gear blank and mandrel.
The mandrel design allows repeatability of machining the holes with the two stated
methods. After Set 1 holes were created, the gear blank was removed from the
mandrel and then placed back on with a 30 offset. Sets 3 and 4 holes were produced
Figure 15. Gear Blank Manufacturing assembly crosssection
7/24/2019 Drive Pin Analysis
26/53
7 Measurements
The gear blank hole sets were measured using
both a Klingelnberg P65 Gear Measurement
Machine, as shown in Figure 17 and a Zeiss
WMM850 Coordinate Measurement Machine,
as shown in Figure 18.
Four measurement datasets were produced. The
first three gave data on:
PCD of each hole set
True diameter of all twenty four holes Centre coordinates for each of the holes
These were found using the P65 machine. The
fourth and final measurement found was the form of two chosen holes which was
measured using the WMM850 machine.
Figure 17. Klingelnberg P65 GearMeasurement Machine
7/24/2019 Drive Pin Analysis
27/53
7.1 Measurement Results
A full set of the first 3 data set measurements can be found in the appendix, whilst a
condensed version is represented in Table 13.
Set 1
This set was completed by plunging an 15mm Slot Drill.
The PCD of the holes was 160.8 m under specification, however the centre point in
terms of X & Y coordinates was very accurate with deviations of 3.6 m and 2.3 m
respectively.
All six holes diameters in this set were largely out of tolerance. The mean deviationover the specified H7 tolerance of the holes was 385.58 m with a range of 112.1 m
between the holes. The largest diameter measured was 15.4812mm.
The coordinate centres of the holes showed excessive deviation in the X axis while
comparatively small deviation in the Y axis. Holes one and four which had the
7/24/2019 Drive Pin Analysis
28/53
Again the coordinate centres of the holes showed excessive deviation in the X axis
while comparatively small deviation in the Y axis. As with set 1, holes one and four,
which had the largest nominal X value, showed the largest deviation in X axis. The
mean deviation in the X direction was 116.28 m, whereas, in the Y direction the
mean deviation was only 10.63 m.
Set 3
This set was completed by interpolating an 10mm Slot Drill to a diameter of
15mm. Set 3 showed significantly greater accuracy than the first two sets, however,
tolerance was still not met.
The PCD of the holes was only 0.4 m over specification, however the centre point in
terms of X & Y coordinates was less accurate than sets one and two, with deviations
of -31.8 m and -52.8 m respectively.
However, the accuracy of the six holes diameters were greatly improved. The mean
deviation over the specified H7 tolerance of the holes was 14.2 m with a range of
7/24/2019 Drive Pin Analysis
29/53
However, the accuracy of the six holes diameters were greatly improved. The mean
deviation over the specified H7 tolerance of the holes was 11.4 m with a range of
3.2 m between the holes.
Again, the coordinate centres of the holes showed much greater accuracy and showed
no mean difference in the X axis compare to the Y axis. The mean deviation in the X
direction was 4.2 m over tolerance, whereas, in the Y direction the mean deviation
was also 4.2 m.
Form
Two form measurements were also taken as can be seen in Table 12 below. The
measurements were taken with 16 points of contact around the circumference of each
hole. The mean deviation of those points are shown.
As can be seen, the form of the Set 1 hole shows much greater deviation than that of
the hole from Set 3. This was expected due to the inaccuracy of the drilling method
used in Set 1.
7/24/2019 Drive Pin Analysis
30/53
24
Measurement Ideal Measurement Ideal Measurement Ideal Measurement Ideal
mm mm mm m mm mm mm m mm mm mm m mm mm mm m
P CD 1 06 .8 39 2 1 07 0.1608 160.8 P CD 1 06 .8 27 5 1 07 0.1725 172.5 P CD 1 06 .9 99 6 1 07 0.0004 0.4 PCD 107.0085 107 -0.0085 -8.5
x 0.0036 0 0.0036 3.6 x -0.0019 0 -0.0019 -1.9 x -0.0318 0 -0.0318 -31.8 x -0.0287 0 -0.0287 -28.7
y 0.0023 0 0.0023 2.3 y -0.0236 0 -0.0236 -23.6 y -0.0528 0 -0.0528 -52.8 y -0.0461 0 -0.0461 -46.1
H ol e 1 1 5.38 40 1 5.01 8 0.3660 366.0 H ol e 1 1 5.53 97 1 5.01 8 0.5217 521.7 H ol e 1 1 5.03 77 1 5.01 8 0.0197 19.7 H ole 1 1 5. 02 99 1 5. 01 8 0.0119 11.9
x 53.3407 53.5 -0.1593 -159.3 x 53.3607 53.5 -0.1393 -139.3 x 53.4967 53.5 -0.0033 -3.3 x 53.5084 5 3.5 0.0084 8.4
y -0.0073 0 -0.0073 -7.3 y 0.0201 0 0.0201 20.1 y -0.0046 0 -0.0046 -4.6 y 0.0056 0 0.0056 5.6
H ol e 2 1 5.40 53 1 5.01 8 0.3873 387.3 H ol e 2 1 5.48 92 1 5.01 8 0.4712 471.2 H ol e 2 1 5.03 02 1 5.01 8 0.0122 12.2 H ole 2 1 5. 03 07 1 5. 01 8 0.0127 12.7
x 26.6810 26.75 -0.0690 -69.0 x 26.6631 26.75 -0.0869 -86.9 x 26.7471 26.75 -0.0029 -2.9 x 26.7559 26.75 0.0059 5.9
y 46.3244 46.3324 -0.0080 -8.0 y 46.3142 46.3324 -0.0182 -18.2 y 46.3382 46.3324 0.0058 5.8 y 46.3379 46.3324 0.0055 5.5
H ol e 3 1 5.48 12 1 5.01 8 0.4632 463.2
H ol e 3 1 5.45 31 1 5.01 8 0.4351 435.1
H ol e 3 1 5.02 85 1 5.01 8 0.0105 10.5
H ole 3 1 5. 02 75 1 5. 01 8 0.0095 9.5
x -26.6588 -26.75 0.0912 91.2 x -26.6584 -26.75 0.0916 91.6 x -26.7494 -26.75 0.0006 0.6 x -26.7453 -26.75 0.0047 4.7
y 46.3281 46.3324 -0.0043 -4.3 y 46.3318 46.3324 -0.0006 -0.6 y 46.3428 46.3324 0.0104 10.4 y 46.3393 46.3324 0.0069 6.9
H ol e 4 1 5.38 59 1 5.01 8 0.3679 367.9 H ol e 4 1 5.48 74 1 5.01 8 0.4694 469.4 H ol e 4 1 5.03 31 1 5.01 8 0.0151 15.1 H ole 4 1 5. 03 00 1 5. 01 8 0.0120 12.0
x -53.3687 -53.5 0.1313 131.3 x -53.3337 -53.5 0.1663 166.3 x -53.4856 -53.5 0.0144 14.4 x -53.4983 -53.5 0.0017 1.7
y 0.0019 0 0.0019 1.9 y 0.0094 0 0.0094 9.4 y 0.0086 0 0.0086 8.6 y 0.0029 0 0.0029 2.9
H ol e 5 1 5.39 60 1 5.01 8 0.3780 378.0 H ol e 5 1 5.53 72 1 5.01 8 0.5192 519.2 H ol e 5 1 5.03 17 1 5.01 8 0.0137 13.7 H ole 5 1 5. 03 04 1 5. 01 8 0.0124 12.4
x -26.6578 -26.75 0.0922 92.2 x -26.6464 -26.75 0.1036 103.6 x -26.7376 -26.75 0.0124 12.4 x -26.7461 -26.75 0.0039 3.9
y - 46. 3145 - 46.3324 0.0179 17.9 y - 46. 3329 - 46.3324 -0.0005 -0.5 y - 46. 3293 - 46.3324 0.0031 3.1 y -46.3335 -46.3324 -0.0011 -1.1
H ol e 6 1 5.36 91 1 5.01 8 0.3511 351.1 H ol e 6 1 5.41 95 1 5.01 8 0.4015 401.5 H ol e 6 1 5.03 22 1 5.01 8 0.0142 14.2 H ole 6 1 5. 02 79 1 5. 01 8 0.0099 9.9
x 26.6887 26.75 -0.0613 -61.3 x 26.6400 26.75 -0.1100 -110.0 x 26.7539 26.75 0.0039 3.9 x 26.7506 26.75 0.0006 0.6
y - 46. 3074 - 46.3324 0.0250 25.0 y - 46. 3174 - 46.3324 0.0150 15.0 y - 46. 3304 - 46.3324 0.0020 2.0 y -46.3270 -46.3324 0.0054 5.4
Deviation Deviation Deviation
Set 1 Set 2 Set 3 Set 4
Deviation
Table 13. Measurements for the 4 sets including the comparator offset
7/24/2019 Drive Pin Analysis
31/53
7.2 Measurement observations
The most important thing to note is that all twenty four holes were outside tolerance.
That being said, there was significant difference in deviations between the first two
hole sets and the third and fourth. Clearly, using the method of plunging a slot drill
of the same diameter is largely inaccurate compared to the interpolating method.
The head of the 5-Axis machine is direct drive which may help explain the larger
deviation in the X direction for Sets 1 & 2. Having the direct drive has less rigidity
than a conventional belt driven 3-Axis machine. Also one of the degrees of freedom
in the 5 Axis machine is rotational along the X axis which again, partly explains the
larger deviations.
The measurements significantly show how drilling methods and skilled technicians
play a vital role in 21 st century manufacture of highly accurate components. To gain
tolerance of holes, it is standard practice to interpolate holes to a known offset under
the required diameter. Then the hole is measured and the accuracy of the offset is
accounted for in the final stage of producing a hole to tolerance. While this was not
7/24/2019 Drive Pin Analysis
32/53
8 Pin Contact Analysis
With the true measurements known for each set of holes, accurate 3D models were
built to analyse how each pin would contact relative to each other within each
respective set.
As the gears within the test rig can be set to run in both directions, pin contact was
analysed for both a clockwise and counter-clockwise rotation. The distance each pin
had to bend to fully contact and in which order they would contact was evaluated.
By calculating the maximum deflection using equation (7) for a range of torques
from 6000Nm to 1000Nm, a full picture can be built up on how each hole set would
perform. The distance to contact vs deflection was compared using Table 14.
Table 14 . Deflection values needed for pin contact
Number of pins
Deflectionat 6000
Nm (m)
Deflectionat 5000
Nm (m)
Deflectionat 4000
Nm (m)
Deflectionat 3000
Nm (m)
Deflectionat 2000
Nm (m)
Deflectionat 1000
Nm (m)
7/24/2019 Drive Pin Analysis
33/53
For Set 2, in the counter-clockwise rotation, the contact distances ranged 235.9 m,
with the largest being 94.0 m for the third pin to contact. In the clockwise rotation,
the contact distances ranged 126.7 m, with the largest being 76.3 m for the third pin
to contact.
Again at the highest torque, in the both the counter-clockwise and clockwise rotation,
only the first tow pins will ever contact.
For Set 3, in the counter-clockwise rotation, the contact distances ranged 17.8 m,
with the largest being 5.8 m for the third pin to contact. In the clockwise rotation,
the contact distances ranged 18.9 m, with the largest being 9.9 m for the third pin to
contact.
In the counter-clockwise rotation, all pins will contact above a torque of 2000Nm,
where the sixth pin starts to contact at a torque of approximately 1500Nm. In the
clockwise rotation, all the pins will contact from a torque above 1000Nm.
Set 4 had the best performance. In the counter-clockwise rotation, the contact
distances showed the smallest range of any set at 5.7 m, with the largest being
7/24/2019 Drive Pin Analysis
34/53
9 Discussion
The ultimate aim of the project was to fully analyse a pin drive design using FEA
once measurements were taken after a Nitriding heat treatment process.
Unfortunately due to time constraints, the heat treatment and full FEA of a final drive
setup could not be carried out. That being said, the results obtained in the project
have successfully shown optimum requirements for a pin drive to work successfully.
Knowing the gear sizing and torque values, it was determined using 34CrNiMo6
Steel (En24) that 6 pins of 15mm with a bending arm length of 12mm would create
the right balance of sharing the load and giving a necessary flexibility for bending to
allow all the pins to contact as long as components are manufactured to correct
tolerance.
Using an interference fit with a profiled pin design allowed many complexities of
calculations and analysis to be removed, whilst providing functionality. Whilst a high
enough interference fit would be difficult to achieve, using a sensible choice of s 6
minimised gap separation down to 17 m of the pin contact the hub. A fillet of 1mm
7/24/2019 Drive Pin Analysis
35/53
10 Conclusion
With sensible material choice for the components, it was shown, that by calculating
the stresses and evaluating the von Mises criterion, that using six pins with a design
of 15mm and a bending arm length of 12mm would provide a relevant safety factor
of 1.5 in transmitting 6000Nm of torque through the gears in the test rig.
A sensible interference fit of s 6 was shown to provide a balanced pressure to reduce
the pins separation to 17 m, whilst negating the need for costly process to use a high
interference fit.
Using a fillet of 1mm on the hole edges was shown to be the most effective profiling
to reduce stress concentration where pins are bending against the hub.
Manufacturing and creating the holes accurately proved to be the biggest factor in
achieving a workable design. Plunging a slot drill proved highly inaccurate with a
maximum deviation of 519.2 m for the diameter. In comparison, interpolating the
holes proved much greater accuracy with the largest deviation of 19.7 m for the
7/24/2019 Drive Pin Analysis
36/53
11 Further Work
The next part of the process would be for the gear blank to undergo a Nitriding heat
treatment cycle as is normal with the gears used in the test rig.
Another round of measurements would be needed to evaluate any deviation in the
holes during the heat treatment.
At this stage, a full model of the pins, hub and gear blank could be accurately
modelled and analysed using FEA software. This would help understand how the
pins would share the load and see how the stress was distributed across the 6 pins.
Once that knowledge was acquired, a prototype could be used on an existing rig to
prove performance. Strain gauges could be placed on the hub hole entrance to
measure if plastic deformation was occurring.
7/24/2019 Drive Pin Analysis
37/53
Bibliography
Granta (2015) CES EduPack 2014 [Computer program]. Available at:
http://www.grantadesign.com/education/edupack/ (Accessed: 18 March 2015)
Macreadys Standard Stock Range of Quality Steels and Specifications (1995)
London: Royal Print Limited. Seventh Edition
British Standards Institution (1983) BS970: Part 1:1983: Wrought steels for
mechanical and allied engineering purposes . Available at:http://www.bsigroup.co.uk/ (Accessed: 13 February 2015).
British Standards Institution (2006) BS EN 10083-3:2006: Steels for quenching
and tempering. Available at: http://www.bsigroup.co.uk/ (Accessed: 16 February
2015).
British Standards Institution (1976) BS S 156:1976 : 4% nickel-chromium-molybdenum case-hardening steel (vacuum arc remelted) billets, bars, forgings and
parts. Available at: http://www.bsigroup.co.uk/ (Accessed: 13 March 2015).
Bhler Uddeholm (2015) En36A Case hardening steel Datasheet Available at:
http://www.buau.com.au/media/EN36A.pdf (Accessed: 05 May 2015).
7/24/2019 Drive Pin Analysis
38/53
British Standards Institution (2010) BS EN ISO 286-1:2010 Geometrical product
specifications (GPS) ISO code system for tolerances on linear sizes. Available at:
http://www.bsigroup.co.uk/ (Accessed: 13 March 2015).
ANSYS (2015) ANSYS Workbench 15.0 [Computer program]. Available at:
http://www.ansys.com/Products/Workflow+Technology/ANSYS+Workbench+Platfo
rm (Accessed: 24 March 2015)
7/24/2019 Drive Pin Analysis
39/53
12 Appendix
Full Calculations for final design
Initial Calculations
Calculating Force:
=
=6000 0.0535 = 112150
Calculating Bending Stress:
=32
=321121500.0120.015
7/24/2019 Drive Pin Analysis
40/53
= 1.3458 Interference needed:
= 2( )
=20.0150.031.345810
20910 0.050.015
= 212 Pressure for s 6max interference fit:
= ( )
2
=209100.009257.527.525 = 114.12
7/24/2019 Drive Pin Analysis
41/53
Measurements
7/24/2019 Drive Pin Analysis
42/53
7/24/2019 Drive Pin Analysis
43/53
7/24/2019 Drive Pin Analysis
44/53
7/24/2019 Drive Pin Analysis
45/53
7/24/2019 Drive Pin Analysis
46/53
7/24/2019 Drive Pin Analysis
47/53
7/24/2019 Drive Pin Analysis
48/53
7/24/2019 Drive Pin Analysis
49/53
Form measurements
7/24/2019 Drive Pin Analysis
50/53
k
Manufacture
Drawings
7/24/2019 Drive Pin Analysis
51/53
l
7/24/2019 Drive Pin Analysis
52/53
m
7/24/2019 Drive Pin Analysis
53/53
n