in cooperation with
YiPing Jin
Long Tao
Department of Mechanical Engineering Blekinge Institute of Technology
Karlskrona Sweden
2017
Abstract
Nowadays, people have a boat of themselves become more and more popular. People use their boat for fishing trip and taking holiday. However, most of them do not want to take care of their boat by themselves. One of the reasons might be the place of a boat occupied. Recently, a method has been used is to store boat on the Boat Hotel. They pay for the rent of a boat garage and also hire someone to take care of their boat. Place the boat on the boat shelf with several layers is the most common method. They use forklift to take in/out the boat when boat owner need use their boat. On the conditional of this situation, if we want to take a boat which is inside of boat shelf, then we need take all outside boat out. It’s really an inefficiency way, so we need improve it.
In this study, we aim to design a Boat Storage System based on the existing shelf and meet all requirement of existing boat. This system should be reliable, efficient, economic, operable and flexible.
The main function of the Boat Storage System is to take in/off the boat more quickly and automatically and efficiently. The system is similar with the stereo parking garage. Which have a paternoster controlled by PLC program. Consider of the boat is heavier than the car. Our storage structure should be more stable.
Our design only need one person to operate it. The whole process will cost few seconds. This building will be established in the water. Therefore, the owner only need to push the button and then the boat will be prepared in the water automatically.
The modelling and assembly was designed in Autodesk Inventor 2017. This hardware circuit of PLC was drawn in AutoCAD. The software to design the PLC is GX Works 2. And we used ANSYS Workbench 17.2 to analysis the structure. The analysis will prove the structure is safety and strong enough. And the simulation will prove the system is possible. Our conclusion is that this system has a good future and general application in the market.
Acknowledgements
Firstly, we would like to express our sincerest and deepest gratitude to our project supervisor Mr. Markus Wejletorp because he gave us so many help about whole thesis, from proposal phase he give us many useful advices so we can choose this interesting Boat storage system, then he not only admitted but also communicate with us about the time plan change of thesis.
Secondly, we are very appreciating for our 3+1 project manager Dr. Sharon Kao-Walter. Because she gave us important support including technical guidance and practical suggestions. Moreover, she played an indispensable role in communicating our Chinese universities with BTH about our project.
Last but not least, we shall show our sincerest and deepest thanks to Mr. Shen Yu and Mr. Hang Yayu, two dedicated and responsible professors, whom also helped us a lot about coordinating our credits between BTH and our home universities.
Contents
Abstract ... 3
Contents ... 7
List of figures ... 13
List of tables ... 17
List of symbols ... 19
List of acronyms ... 21
1
Chapter: Introduction ... 22
2
Chapter: Survey of related work ... 23
2.1 Moving Manually ... 23
2.2 Launching Manually ... 23
3
Chapter: Problem statement, objectives and main
contribution ... 25
4
Solution ... 26
4.1 Problem statement ... 26
4.2 Alternative Solution ... 26
4.2.1 Place arrangement of 60 boats ... 26
4.2.2Transfer method on vertical direction ... 28
4.2.3Mechanical method for take boat in or out ... 29
4.2.4Transfer method on horizontal direction ... 29
4.3 Final Solution ... 30
5
Chapter: Modelling ... 31
5.1 Main frame ... 34
5.1.1Vertical support bar ... 35
5.1.2Horizontal support bar ... 36
5.2 Boat support frame ... 39
5.3 Boat support board ... 41
5.4 Ball screw part ... 42
5.4.1Ball screw ... 42
5.4.2Nuts holder ... 44
5.4.3Bearing ... 44
5.5 Power mechanism of ball screw ... 45
5.5.1Motor ... 45
5.6 Middle movement frame ... 46
5.6.1Vertical support bar ... 47
5.6.2Horizontal support bar ... 48
5.7 Bottom orbits and bottom movement part ... 50
5.7.1Orbits ... 50
5.7.2Bottom movement part ... 51
5.8 Boat transfer device among horizontal direction ... 52
5.8.1Vertical movement frame ... 53
5.8.2Long guide and long slider ... 54
5.8.3 Rack and boat hold board ... 56
5.9 Support slider and guide ... 57
5.10 Boat ... 58
5.11 Control Menu ... 59
6
Chapter: Selection of power and ball screw ... 60
6.1.5.1 Selection of Ball screw diameter ... 63
6.1.5.2Calculate maximum axial stress ... 64
6.1.5.3Calculate allowance axial stress for check ... 65
6.1.5.4Calculate and check of ball screw rotate speed... 65
6.1.5.5The result of ball screw selection ... 66
6.1.6Selection of Nuts ... 66
6.1.6.1Calculate and check of axial allowance stress of Nuts ... 66
6.1.7Calculating the Rated Life of Ball screw ... 67
6.1.8Static safety Factor ... 68
6.2 Selection of Motor ... 68
6.2.1Calculate Drive torque on the conditional of stable speed ... 68
6.2.2Calculate Motor Drive torque on the conditional of Accelerate speed ... 69
6.2.3Calculate the motor torque in different condition ... 70
6.2.4Calculate effective torque value ... 71
6.2.5Selection of motor ... 71
6.2.5.1Rotate speed of motor ... 71
6.2.5.2 Torque of motor ... 71
6.2.5.3Moment of inertia of motor ... 71
7
Control System ... 73
7.1 System select ... 73
7.2 Port Assignment ... 74
7.2.1Inuput Port / X Port ... 74
7.2.2Output Port / Y Port ... 75
7.2.3Auxiliary Register / M ... 75
7.2.4Data Register / D ... 76
7.3 Step Flow Chat ... 76
7.3.1.1 Step1 – Main Step ... 76
7.3.1.2Step2 – Data Receive ... 77
7.3.1.3Step 3 – Up Process ... 78
7.3.1.4Step 4 – Take In/Out Process ... 79
7.3.1.5Step 5 – Down Process ... 80
7.3.1.6Step 6 – Take In/Out Switch Process ... 81
7.3.2Total Step Flow Chat ... 82
7.3.3PLC Program ... 83
8
Operation Panel ... 84
8.1 Operation Panel Requirement ... 84
9.2 Transmission Shaft – Simulation in software(FEM) ... 99
9.2.1Von Mises Criterion ... 99
9.2.2Von Mises Yield Criterion ... 99
9.2.3Analysis Conditions ... 100
9.3 Transmission Shaft – Compare ... 103
9.4 Frame Analysis ... 103
10
Chapter: Conclusion and future work ... 105
10.1 Conclusion ... 105
10.2 Future work ... 105
Reference ... 106
Appendix 1: Boat Storage System ... 108
Appendix 2: Boat Hold Board ... 109
Appendix 3: Boat Support Frame ... 110
Appendix 4: Boat Transfer Hold Frame ... 111
Appendix 5: Main Frame Vertical Support Bar ... 112
Appendix 6: Main Frame Horizontal Long Support Bar ... 113
Appendix 7: Main Frame Horizontal Short Support Bar ... 114
Appendix 8: Boat ... 115
Appendix 9: Long Guide ... 116
Appendix 10: Long Slider ... 117
Appendix 11: Boat Transfer Hold Board ... 118
Appendix 12: Middle Frame Vertical Support Bar ... 119
Appendix 13: Middle Frame Horizontal Long Support Bar 120
Appendix 14: Middle Frame Horizontal Short Support Bar 121
Appendix 15: SFC program for PLC ... 122
List of figures
Figure 2-1 Moving Manually [1] ... 23
Figure 2-2 Launching Manually [2] ... 24
Figure 4-1 Solution 1[3] ... 27
Figure 4-2 Solution 2 [4] ... 27
Figure 4-3 Scissors lift machine [5] ... 28
Figure 4-4 Gear rack ... 29
Figure 4-5 Bottom movement ... 30
Figure 5-1 Final model ... 32
Figure 5-2 Front view of final model ... 32
Figure 5-3 Left view of final model ... 33
Figure 5-4 Main frame ... 34
Figure 5-5 Vertical support bar ... 35
Figure 5-6 Rib structure ... 35
Figure 5-7 Long horizontal support bar ... 36
Figure 5-8 Short horizontal support bar ... 37
Figure 5-9 Both side bottom support frame ... 38
Figure 5-10 Bottom support frame ... 39
Figure 5-11 Boat support frame ... 39
Figure 5-12 Boat support frame support bar ... 40
Figure 5-13 Boat support board ... 41
Figure 5-14 Install of boat support board... 41
Figure 5-15 Ball screw working mode ... 42
Figure 5-16 Ball screw ... 43
Figure 5-17 Nuts holder ... 44
Figure 5-18 Bearing ... 44
Figure 5-20 Motor ... 46
Figure 5-21 Middle movement frame ... 47
Figure 5-22 Vertical support bar ... 47
Figure 5-23 Horizontal support bar ... 48
Figure 5-24 Horizontal support bar ... 49
Figure 5-25 Orbits ... 50
Figure 5-26 Bottom movement part ... 51
Figure 5-27 Boat transfer device among horizontal direction ... 52
Figure 5-28 Bottom view of boat transfer device among horizontal direction ... 53
Figure 5-29 Vertical movement frame ... 53
Figure 5-30 Long slider and long guide working mode ... 54
Figure 5-31 Long slider ... 55
Figure 5-32 Long guide ... 56
Figure 5-33 Rack and boat hold board ... 57
Figure 5-34 Support slider and guide ... 58
Figure 5-35 Boat ... 58
Figure 5-36Control Menu ... 59
Figure 6-1 Key words of advantages and disadvantages of four technology [6] ... 60
Figure 6-2 Ball screw [7] ... 61
Figure 6-3 Accuracy grade sheet [10] ... 62
Figure 7-2 Flow Chat for Step 2 – Data Process... 77
Figure 7-3 Flow Chat for Step 3 – Up Process ... 78
Figure 7-4 Flow Chat for Step 4 – Take In/Out Process ... 79
Figure 7-5 Flow Chat for Step 5 – Down Process ... 80
Figure 7-6 Flow Chat for Step 6 – Take In/Out Switch Process ... 81
Figure 7-7 Total Step Flow Chat... 82
Figure 8-1 Operation Panel ... 84
Figure 8-2 Display ... 85
Figure 8-3 Welcome Interface ... 87
Figure 8-4 Main Loop ... 88
Figure 8-5 Keyboard Detection Program ... 89
Figure 8-6 Key Detection Flow Chat ... 89
Figure 8-7 Key Number Location ... 91
Figure 8-8 Key Arrangement ... 91
Figure 8-9 Reverse Table ... 91
Figure 8-10 Delay Time Calculation ... 93
Figure 8-11 Simulation Platform ... 93
Figure 8-12 Welcome Interface ... 94
Figure 8-14 Simulation ... 94
Figure 8-13 Display 1st Number ... 94
Figure 9-1 Value Kr [16] ... 97
Figure 9-2 Value 𝐾𝑡 [16] ... 97
Figure 9-3 Value q [16] ... 98
Figure 9-4 Haigh-Diagram [16] ... 98
Figure 9-5 The Specimen ... 100
Figure 9-6 Boundary Condition ... 101
Figure 9-7 Initial Conclusion ... 101
Figure 9-9 Refined Mesh Conclusion ... 102
Figure 9-10 Shear Stress ... 103
Figure 9-11 Boundary Condition of Frame ... 104
List of tables
Table 3-1 Boat and Storage Conditions ... 25
Table 4-1 Comparison about two solution ... 28
Table 5-1 Parameter of main frame ... 34
Table 5-2 Parameter and other details of vertical support bar ... 36
Table 5-3 Parameter and other details of long horizontal support bar ... 37
Table 5-4 Parameter and other details of short horizontal support bar ... 38
Table 5-5 Parameter and other details of boat support frame ... 40
Table 5-6 Parameter and other details of ball screw ... 43
Table 5-7 Details of Motor ... 46
Table 5-8 Parameter and other details of vertical support bar ... 48
Table 5-9 Parameter and other details of horizontal support bar ... 49
Table 5-10 Parameter and other details of horizontal support bar ... 50
Table 5-11 Parameter and other details of orbits ... 51
Table 5-12 Parameter and other details of vertical movement frame ... 54
Table 5-13 Parameter and other details of long slider ... 55
Table 5-14 Parameter and other details of long guide ... 56
Table 5-15 Parameter and other details of rack and boat hold board ... 57
Table 5-16 Parameter and other details of boat ... 59
Table 6-1 Result of ball screw selection ... 66
Table 6-2 Result of Motor selection ... 72
Table 7-1 Input Port / X Port Definition Detail ... 74
Table 7-2 Output Port / Y Port Definition Detail ... 75
Table 7-3 Auxiliary / M Register Definition Detail ... 75
Table 7-4 Data / D Register Definition Detail ... 76
Table 8-1 Port Definition ... 86
List of symbols
Symbol Quantity Unit
𝑁𝑀 Motor rated speed r/min
𝑉𝑚𝑎𝑥 Maximum movement speed m/s
𝑃𝐵 Thread pitch mm
i Decelerate rate /
𝑁𝑅 Motor Specific speed r/min
t Time s
F Force N
d Ball screw groove diameter mm
L Ball screw thread distance mm
η Other factor /
𝑛1 Allowance Rotary speed r/min
J Moment of inertia 𝑚𝑚4
ρ Material density Kg/𝑚𝑚3
A Area 𝑚𝑚2
λ Other factor /
f Other factor /
𝐶𝑁 Rated static load N
Ln Normal life rev
𝐶𝑎 Basic dynamic load rate N
𝑓𝑤 Load factor /
𝐿𝑠 Service time in travel distance Km
𝑓𝑠 Static safety factor /
T Torque Nm
𝜇0 Internal friction coefficient of
preload nuts /
List of acronyms
Acronym Unfolding
FEM Finite Element Mothed
1 Chapter:
Introduction
Having an own boat become more popular today. Lots of people use their boat for fishing trip and taking holidays. However, it’s too difficult to take care of their boat. It occupied not only times but also space. Most of the people want their boat prepared before their holiday and store it into the storage automatically after them enjoy their life. Storing their boat in the Boat Hotel is most common method today. Therefore, the only thing they should do is to arrange a nice trip without preparing their boat.
After searching the internet, we found the common method used by Boat Hotels. It is to placing the boats on the shelf with several layers. Whether the customer want put in or out their boats. The workers will drive a forklift to the parking position and take the boat in or out. After that, the workers also need to help the customers launch their boats. The whole process is manual. It’s very inefficiency and waste lots of times.
In this report, we designed a new system called Boat Storage System to make the whole process more efficient.
2 Chapter:
Survey of related work
2.1
Moving Manually
In order to take the boat from the storage in and out. The Boat Hotel now have to hire several persons who can drive the forklift. And these persons will use the forklift to carry the boat. It really takes lots of time just take one boat from the storage. The forklift driver should watch out the fork to avoid it injured boats (Figure 2-1).
Figure 2-1 Moving Manually [1]
2.2
Launching Manually
3 Chapter:
Problem statement, objectives and
main contribution
Boat Hotel should have a new system to increase the efficiency. The boat needs to be take in/out the storage more automated. However, the place is limited. Therefore, the area should be as small as possible. Identically, another problem is the management cost. For the current method, the Boat Hotel have to hire some special drivers/workers to take in/out boats by using the forklift. Which is expensive and also inefficiency.
The main objective of the project is to study solve the store problem so it will be easy to get the boat in and out from the store without taking other boats in/out. And also, reduce the management cost of the Boat Hotel.
The mean contribution of this thesis is:
1. Draw the whole system in Autodesk Inventor 2017;
2. Analysis the structure in FEM method by using ANSYS Workbench 17.2;
3. Select suitable motor and ball screw for this system;
4. Edit the PLC programme for this system by using GX Works 2. The boat and the storage have following conditions (Figure 3-1).
Table 3-1 Boat and Storage Conditions
Type Unit Value
Boat Size
Maximum Length m 7.5
Maximum Width m 2.5
Maximum Hight m 3
Dead rise degree ~55º 20 º
Storage condition
Number of Layer layers 6 Number of Boats
each layer per layer boats 10 Total number of
4 Solution
4.1
Problem statement
According to the requirement of our design which is make whole boat storage system become reliable, efficient, economic, automatically and at the same time the whole boat storage system should admit 60 boats. So the main problem is:
How to arrange the place of 60 boats?
What kind of mechanism we should use for transfer boat on vertical direction?
What kind of mechanism we should use for take boat in or out?
What kind of transfer method we can use for transfer boat on horizontal direction?
4.2
Alternative Solution
4.2.1 Place arrangement of 60 boats
After we did some survey about existing boat storage method, we came up with several ideas about the place arrangement of 60 boats.
Figure 4-1 Solution 1[3]
Solution 2: Another idea is build boat shelf like following shows, it also can meet our design requirement.
Figure 4-2 Solution 2 [4]
Table 4-1 Comparison about two solution Place
requirement requirement Price Efficiency of boat Number Solution
1 area Need big Expensive High ≥ 60
Solution
2 area Need small Cheap Normal ≥ 60
After we did comparison, considering solution 2 is more flexible and cheap and at the same time also can meet our design requirement. So, for Place arrangement of 60 boats, we decide choose solution 2.
4.2.2 Transfer method on vertical direction
Solution 2: Ball screw
For solution 1, we think it cannot satisfy the height of our boat storage system, when this kind of structure go too high, the whole frame will become unstable.
For solution 2, it can satisfy our design, so we choose solution 2 to be our transfer method on vertical direction.
4.2.3 Mechanical method for take boat in or out
Solution: Gear rack
Figure 4-4 Gear rack
Considering solution can transfer boat on both direction, so we choose this solution.
4.2.4 Transfer method on horizontal direction
Figure 4-5 Bottom movement
4.3
Final Solution
5 Chapter: Modelling
We modelling by using software Inventor 2017.
We model Boat Storage System according to the data from real life, the data shows below:
Data request based on existing boat: Maximum Boat Length= 7.5m Maximum Boat Width= 2.5m Maximum Boat Height= 3m Maximum Boat weight=2000 kg Maximum number of Layer=6 Dead rise= 20-55deg
Number of Boats each layer= 10
Figure 5-1 Final model
Figure 5-3 Left view of final model
Our design which is boat storage system can build in the water. When people want to use their boat, by using PLC achieve automatically control which means the boat hold board can go down under water, then people just need drive boat out of boat hold board. It also can build on the ground depends on different situation. This kind of boat storage system is pretty convenient for take in or out boat from boat shelf.
Our boat storage system consists of ten parts: First part main frame;
Second part boat support frame; Third part boat support plane; Fourth part ball screw part;
Fifth part power mechanism of ball screw; Sixth part middle movement frame;
Seventh part bottom orbits and bottom movement part; Eighth part boat transfer device among horizontal direction; Ninth part support sliders and guide;
Tenth part boat;
5.1
Main frame
Main frame is shown below:
Figure 5-4 Main frame
Main frame consists of vertical support bar and parallel support bar and bottom support frame.
Table 5-1 Parameter of main frame
Length/mm Width/mm Height/mm
5.1.1 Vertical support bar
Figure 5-5 Vertical support bar
All vertical support bar has rib structure to enhance strength of main frame.
Table 5-2 Parameter and other details of vertical support bar
Name Value Units
Length 220 mm
Width 220 mm
Height 23250 mm
Material Stainless steel N/A
Number 24 N/A
5.1.2 Horizontal support bar
Table 5-3 Parameter and other details of long horizontal support bar
Name Value Units
Length 120 mm
Width 120 mm
Height 7480 mm
Material Stainless steel N/A
Number 84 N/A
Table 5-4 Parameter and other details of short horizontal support bar
Name Value Units
Length 120 mm
Width 120 mm
Height 3000 mm
Material Stainless steel N/A
Number 140 N/A
5.1.3 Bottom support frame
Figure 5-10 Bottom support frame
5.2
Boat support frame
We build this kind of frame to hold boat, for this part, considering existing boat support part, we came up with a new support frame which is like following picture; there has six single support bar on the frame and the horizontal distance between each pair of support is different.
Table 5-5 Parameter and other details of boat support frame
Name Value Units
Length 7480 mm
Width 2460 mm
Height 140 mm
Material Stainless steel N/A
Number 60 N/A
Figure 5-12 Boat support frame support bar
5.3
Boat support board
Figure 5-13 Boat support board
As you can see, this board has many small hole, this kind of design is for dry boat. When boat come from the water, there will have some water on the face of boat bottom. So, we design this kind of support board to dry boat bottom.
Figure 5-14 Install of boat support board
5.4
Ball screw part
5.4.1 Ball screw
Ball screw is main power of transfer boat on vertical direction, so this part is quite important for whole system. In our model below, we have two ball screw to transfer boat on vertical direction, the support structure will become more stable with two ball screw hold boat.
Figure 5-16 Ball screw
Table 5-6 Parameter and other details of ball screw
Name Value Units
Diameter 120 mm
Length 15000 mm
Material GCr15SiMn(GB/JB) N/A
5.4.2 Nuts holder
Figure 5-17 Nuts holder
5.5
Power mechanism of ball screw
Power mechanism of ball screw is shown below:
Figure 5-19 Power mechanism of ball screw
Use this kind of mechanism can make sure two ball screw rotate speed and thread rotation direction is same.
5.5.1 Motor
Figure 5-20 Motor
Table 5-7 Details of Motor
Mode 1LA8/1PQ8
Figure 5-21 Middle movement frame
5.6.1 Vertical support bar
Table 5-8 Parameter and other details of vertical support bar
Name Value Units
Length 300 mm
Width 300 mm
Height 22000 mm
Material Stainless steel N/A
Number 4 N/A
5.6.2 Horizontal support bar
Table 5-9 Parameter and other details of horizontal support bar
Name Value Units
Length 300 mm
Width 300 mm
Height 7200 mm
Material Stainless steel N/A
Number 4 N/A
Table 5-10 Parameter and other details of horizontal support bar
Name Value Units
Length 300 mm
Width 300 mm
Height 3000 mm
Material Stainless steel N/A
Number 4 N/A
5.7
Bottom orbits and bottom movement part
5.7.1 Orbits
Table 5-11 Parameter and other details of orbits
Name Value Units
Length 19000 mm
Material Stainless steel N/A
Number 2 N/A
5.7.2 Bottom movement part
In the model below, we have four wheels for orbits. We have inside motor to be the power of these wheel.
Figure 5-26 Bottom movement part
5.8
Boat transfer device among horizontal direction
As you can see from picture below, this part consists of movement frame among vertical direction, two pair of long guide and long slider, boat hold board, rack, two motors.
Figure 5-27 Boat transfer device among horizontal direction
Figure 5-28 Bottom view of boat transfer device among horizontal direction
5.8.1 Vertical movement frame
Table 5-12 Parameter and other details of vertical movement frame
Name Value Units
Length 6960 mm
Width 3670 mm
Height 300 mm
Material Stainless steel N/A
Number 1 N/A
5.8.2 Long guide and long slider
Use this kind of slider and guide will make the whole structure become more stable. As you can see from the model, there have a lot of small hole on the long slider and long guide, with these small holes we can achieve accurate positioning of the horizontal direction.
Figure 5-31 Long slider
Table 5-13 Parameter and other details of long slider
Name Value Units
Length 7800 mm
Width 275 mm
Height 90 mm
Material Stainless steel N/A
Figure 5-32 Long guide
Table 5-14 Parameter and other details of long guide
Name Value Units
Length 7800 mm
Width 65 mm
Height 60 mm
Material Stainless steel N/A
Number 2 N/A
Figure 5-33 Rack and boat hold board
Table 5-15 Parameter and other details of rack and boat hold board
Name Value Units
Length 7800 mm
Width 1230 mm
Height 90 mm
Material Stainless steel N/A
Number 1 N/A
5.9
Support slider and guide
Figure 5-34 Support slider and guide
Table 5-16 Parameter and other details of boat
Name Value Units
Length 6000 mm
Width 1750 mm
Height 2363 mm
Number 60 N/A
5.11
Control Menu
We design this control menu for control PLC working.
6 Chapter:
Selection of power and ball screw
In our thesis, we use ball screw to transfer boat on vertical direction.
There has four technology that can transfer boat on vertical direction, we find some key words of advantages and disadvantages of four technology.
Figure 6-1 Key words of advantages and disadvantages of four technology [6]
After comparison, we decide to choose ball screw, because for our design, we need transfer boat on vertical direction and also:
High precision; High speed; High rigidity;
Figure 6-2 Ball screw [7]
6.1
Selection of ball screw [8]
6.1.1 Define material of ball screw
The material we use for ball screw is GCr15SiMn (GB/JB) or 100CrMn6[9] (DIN). It also called Rolling bearing steel.
6.1.2 Accuracy Grade
Figure 6-3 Accuracy grade sheet [10]
Accuracy grade is different in different country, here we choose C5 according to the table above.
6.1.3 Thread pitch
Thread pitch is distance of nuts move up or down when screw rotate 360 degree.
When motor have decelerator, according to the define of Thread pitch, the relationship of Motor Rated speed 𝑁𝑀 , Maximum Movement speed 𝑉𝑚𝑎𝑥,
Thread pitch𝑃𝐵 and Decelerate rate ⅰis:
𝑁𝑀 =𝑉𝑚𝑎𝑥 ∗ 10
3∗ 60
𝑃𝐵 ≥ 𝑉𝑚𝑎𝑥∗ 10
3∗ 60
𝑁𝑅∗ 𝑖
Here, because we need transfer boat very stable, so we need a stable speed. We define 𝑉𝑚𝑎𝑥=0.5m/s, assume 𝑁𝑅=3000r/min, 𝑖=1. So, we obtain,
𝑃𝐵 ≥
0.5 ∗ 103∗ 60
3000 ∗ 1 = 10𝑚𝑚 We choose 𝑃𝐵=15mm.
As we know 𝑉𝑚𝑎𝑥=0.5m/s, 𝐿𝑚𝑎𝑥=18m, so we can calculate time t,
t = 𝐿𝑚𝑎𝑥 𝑉𝑚𝑎𝑥 =
18
0.5= 36𝑠
From the top of the boat transfer to ground, we will use 36s.
6.1.4 Ball screw support mode
As for our circumstances, we need ball screw bar hold boat and high precision, high speed, high rigidity and also the ball screw bar is pretty long, so we choose one side fixed as support part which is down part of boat hold shelf, another fixed with nuts which is boat hold board. The support mode is like following picture.
Figure 6-4 Ball screw support mode[8]
6.1.5 Selection and check of Ball screw diameter
6.1.5.1 Selection of Ball screw diameter
According to relevant accuracy grade and length of ball screw, diameter must satisfy axial clearance;
According to standard combination of thread distance—ball screw diameter, select the final diameter.
Figure 6-5 Standard combination of thread distance—ball screw diameter [11]
According to a sheet form Internet, our accuracy grade is C5 and axial clearance is 15mm, so we choose diameter is D=120mm.
6.1.5.2 Calculate maximum axial stress
6.1.5.3 Calculate allowance axial stress for check
Maximum axial stress of Ball screw on the conditional of do not Yield: 𝑃1 = 𝜂 ∗𝑑
4
𝐿2 ∗ 104 = 104 ∗
12.54
152 ∗ 10 = 10850000𝑁 > 21000𝑁
d--- The minimum diameter of the screw groove, mm; L— Ball screw thread distance, mm;
𝜂—Other factor, 𝜂 = 10
According to the result we obtain, allowance axial stress is more than final axial stress, so it is safe.
6.1.5.4 Calculate and check of ball screw rotate speed Calculate of Allowance rotate speed of ball screw:
𝑛1 = 60𝜆2 2𝜋𝐿2√ 𝐸 ∗ 103 ∗ 𝐽 𝜌𝐴 𝑥0.8 = 𝑓 𝑑 𝐿2𝑥107 𝑛1 = 15.1x12.5 152 𝑥107 = 83888𝑟/𝑚𝑖𝑛
𝑛1--- Allowance rotate speed, r/min;
L— Ball screw thread distance, mm; J--- Moment of inertia, J =64𝜋x𝑑4, 𝑚𝑚4;
d--- The minimum diameter of the screw groove, mm;
𝜌---The material density of the ball screw, (7.8x106kg/𝑚𝑚3) A---The smallest area of the cross-sectional, A=𝜋4𝑑2, 𝑚𝑚2; 𝜆, 𝑓---Other factor, 𝑓 = 15.1
DN value:
DN≤70000-100000 𝑛1 ≤DN
6.1.5.5 The result of ball screw selection
Table 6-1 Result of ball screw selection
Name Value Symbol Units
Accuracy
Grade C5 N/A N/A
Thread Pitch 15 𝑷𝑩 mm Ball screw diameter 120 D mm Ball screw allowance rotate speed 83888 𝒏𝟏 r/min 6.1.6 Selection of Nuts
6.1.6.1 Calculate and check of axial allowance stress of Nuts
Considering Inertia force effective, we have to add a safety factor on Rated static load which is𝑓𝑁.
The actual allowance axial force of nuts is: 𝐹𝑚𝑎𝑥 =
𝐶𝑁
𝑓𝐵
𝐶𝑁--- Rated static load, N;
𝐹𝑚𝑎𝑥--- The actual allowance axial force, N;
𝑓𝐵---static safety factor, (1.0-1.3)
6.1.7 Calculating the Rated Life of Ball screw
The service life of ball screw is calculated from the equation below using the basic dynamic loading rating (𝐶𝑎) and the applied axial load.
Nominal life: Ln = ( 𝐶𝑎 𝑓𝑤. 𝐹𝑎 ) 3 𝑥106 Ln = (18050000 1.3 ∗ 21000) 3 𝑥106 = 6.61𝑥1011𝑟𝑒𝑣
Ln--- Nominal life, (rev);
𝐶𝑎--- Basic dynamic loading rating, (N); 𝐹𝑎---Applied axial load,(N);
𝑓𝑤---Load factor, 1.3
Figure 6-6 Value of fw [12] Service life time in Travel distance:
The Service life time in Travel distance can be calculated by using equation below: 𝐿𝑠 =𝐿 ∗ 𝑃𝐵 106 𝐿𝑠 = 6.61𝑥10 11∗ 15 106 = 99.15𝑥105𝑘𝑚
𝑃𝐵--- Thread pitch, mm;
6.1.8 Static safety Factor
The basic dynamic loading rating (𝐶𝑎) generally equal to Maximum axial
stress of Ball screw. So we can calculate the static safety factor by using equation below: 𝐹𝑎𝑚𝑎𝑥 = 𝐶𝑎 𝑓𝑠 𝐹𝑎𝑚𝑎𝑥 = 10850 1.3 = 8346.15𝐾𝑁 𝐹𝑎𝑚𝑎𝑥---Permissible axial load, KN;
𝐶𝑎--- Basic dynamic loading rating, KN;
𝑓𝑠---Static safety factor, 1.3
Figure 6-7 Value of fs [12]
6.2
Selection of Motor
6.2.1 Calculate Drive torque on the conditional of stable speed
𝐹2--- Boat hold board maximum weight, N; Preload 𝐹0 of Ball nut:
The ball screw which is after preload need a torque to keep ball screw rotate, we can use the equation below to calculate:
𝐹0 =1
3𝐹 = 7000𝑁
Torque 𝑇𝐿 that motor need when move by stable speed:
𝑇𝐿 = (𝐹𝑃𝐵 2𝜋𝜂+ 𝜇0𝐹0𝑃𝐵 2𝜋 ) 1 𝑖x10 −3 𝑇𝐿 = ( 21000 ∗ 15 2𝜋 ∗ 0.85 + 0.2 ∗ 7000 ∗ 15 2𝜋 ) 1 1x10 −3= 75.68𝑁𝑚
𝑇𝐿---When move by a stable speed, motor need torque, Nm; F--- Maximum axial stress, N;
𝐹0---preload of ball nuts, N;
i---Reduction ratio (motor to ball screw),1; 𝑃𝐵--- Thread pitch, mm;
𝜇0---Internal friction coefficient of preload nuts, 0.1-0.3; 𝜂---Ball screw drive efficiency, 85%;
6.2.2 Calculate Motor Drive torque on the conditional of Accelerate speed
When the boat hold board is about to start or stop, there will have an accelerate speed, for ensure motor we used is safe, so we also need calculate this torque.
First step: Calculate the Moment of inertia𝐽𝑠:
𝐽𝑚 = 1x10−3kg/𝑚2 [12] From company THK---The example of select ball screw.
𝐽𝑠=𝐽𝑚∗ 𝐿 = 1.5x10−2kg/𝑚2
According to equation following, we can obtain rotate speed of ball screw when working: 𝑛𝑚𝑎𝑥 = 𝑉𝑚𝑎𝑥∗ 103∗ 60 𝑃𝐵𝑖 𝑛𝑚𝑎𝑥 = 0.5 ∗ 10 3∗ 60 15 = 2000𝑟/𝑚𝑖𝑛
So, we can obtain Angel acceleration, ϵ =2𝜋𝑛𝑚𝑎𝑥
60𝑡1 ϵ--- Agular acceleration, rad/𝑠2
𝑛𝑚𝑎𝑥--- rotate speed of ball screw when working, r/min; 𝑡1--- Acceleration time, s; Calculate𝑡1, 𝑉0=0, 𝑉𝑚𝑎𝑥=0.5m/s, 𝑎=10m/𝑠2 𝑉𝑚𝑎𝑥 = 𝑉0𝑡 +1 2𝑎𝑡1 2 𝑡1 = 0.32𝑠 Then, ϵ =2𝜋𝑥2000 60𝑥0.32 = 654 rad/𝑠 2
Finally, Motor Drive torque on the conditional of Accelerate speed: 𝑇𝑎 = 𝐽𝑠. ϵ = 9.8Nm
6.2.3 Calculate the motor torque in different condition
𝑇𝑔 = 65.88𝑁𝑚
From the equation above, we know that the maximum value of torque is 85.48N /m.
6.2.4 Calculate effective torque value
On the conditional of accelerate speed need torque𝑇𝐾 = 85.48𝑁𝑚, running
time is 𝑡1=0.32s;
On the conditional of stable speed need torque𝑇𝑡 = 75.68𝑁𝑚, running time
is 𝑡2=35.36s;
On the conditional of decelerate speed need torque𝑇𝑔 = 65.88𝑁𝑚, running
time is 𝑡3=0.32s; Stop time is 𝑡4=0s; Then, 𝑇𝑒 = √𝑇𝐾 2𝑡 1+ 𝑇 𝑡2𝑡2+ 𝑇𝑔2𝑡3 + 𝑇𝐾2𝑡4 𝑡1+ 𝑡2+ 𝑡3+ 𝑡4 𝑇𝑒 =75.69Nm 6.2.5 Selection of motor
According to the data we calculated, we can select motor.
6.2.5.1 Rotate speed of motor
𝑁𝑅 ≥𝑉𝑚𝑎𝑥𝑥10
3𝑥60
𝑃𝐵∗ 𝑖 = 2000𝑟/𝑚𝑖𝑛
6.2.5.2 Torque of motor
The maximum output torque 𝑇𝑃𝑚𝑎𝑥≥ 𝑇𝐾;
The rated output torque𝑇𝑅 ≥ 𝑇𝑒;
6.2.5.3 Moment of inertia of motor
After we get this data, we finally choose SIEMENS three phase asynchronous motor [13], specific data shows in following table.
Table 6-2 Result of Motor selection
Mode 1LA8/1PQ8
7 Control System
7.1
System select
For our project, we need a control system. For the system requirement, we have following conditions:
First, the input ports should support DC 12V switching value. Because our Operation Panel will use Single-Chip to receive the floor number and position number. This system should be allowed to get the data as 8 digits switching value which transferred from Chip (The output voltage of the Single-Chip is 5V, but we will use some relay to let the output switching value increase to 12V. More detail will be described on Chapter 8). At the same times, the sensor we use is also DC 12V switching value.
Second, the output ports should support AC 380V Industrial voltage. The motor we selected is SIEMENS three phase asynchronous motor, which required the input voltage equal to AC 380V.
After searching the market, we found that the PLC (Programmable Logic Controller) is the best way for our project. And then we choice the Mitsubishi FX-3U as the final system. Because this PLC has the advantage that other PLC didn’t have or only have few of the following functions:
First, we could programme it by Step Command which only can be used in Mitsubishi’s PLC. And this is also the important reason that we choice brand Mitsubishi but not the SIMENS;
Second, Mitsubishi FX-3U support a special function that former Mitsubishi PLC didn’t have. This special function is that I could use Index Addressing Function. The reason I need it because our project will provide 60 ship’s positions. If we edit these positions’ codes one by one, it will let the programme being too long. Which is also inefficient. But we could reduce and simplified the programme by using Index Addressing Function. We will only need to edit a common programme which can distinguish which position we need to take in or out automatically.
7.2
Port Assignment
7.2.1 Inuput Port / X Port
The input port will mainly receive the Signal from three parts. First one is the Position Sensor Signals, which will be used to check the left’s position. Second one is the Action Sensor Signal, which will tell the PLC if the Ship take in/out from the position to the lift successfully.
The other one is the Required Position’s Signal, which will be used to communicate with Single-Chip. The Required Position’s Signal consist of the Required Ship’s position and floor. The detail Port Arrange is listed in the -Table 7-1.
Table 7-1 Input Port / X Port Definition Detail
Port Application Port Application
X000 Single-Chip ‘PLC-IN’ X020 Position No.0 X001 First Floor Check X021 Position No.1 X002 Second Floor Check X022 Position No.2
X003 Third Floor X023 Position No.3
7.2.2 Output Port / Y Port
The quantity of Output Port is not as much as Input Port have. Because the PLC only needs to control the Motors and feedback the Single-Chip. We use only 9 output ports. The detail is listed on the Table 7-2.
Table 7-2 Output Port / Y Port Definition Detail
Port Application Port Application
Y000 Single-Chip ‘PLC-OUT’ Y014 Single-Area Out Apply
Y010 Up-Motor Y015 Double-Area Out Apply
Y011 Down-Motor Y016 Single-Area In Apply Y012 Front-Motor Y017 Double-Area In Apply
Y013 Back-Motor
7.2.3 Auxiliary Register / M
In the whole program, we used 18 auxiliary registers. They are separate to 4 parts. Form M0 to M2 were used to find the required position is located in Single Area or Double Area. M3 and M4 are used to hold the Floor/Position sensors’ temporary situation. From M10 to M12 are used to judge that whether the input location, which include floor and position’s number, is valid or not. M13 and M14 are two pointers. They help the PLC to judge that the process is take in or take out. From M20 to M27 are used to temporary storage the binary code which translated from 8-BIN code input location number. More details are showed on the Table 7-3.
Table 7-3 Auxiliary / M Register Definition Detail
Port Application Port Application
M0 Single Area M20 BIN => BCD
M1 Double Area M21 BIN => BCD
M2 Neither Single/Double M22 BIN => BCD M3 Auxiliary Floor Register M23 BIN => BCD M4 Auxiliary Position Register M24 BIN => BCD M10 <Valid Area, Invalid M25 BIN => BCD M11 =Valid Area, Valid M26 BIN => BCD M12 >Valid Area, Invalid M27 BIN => BCD M13 Take Out Pointer
7.2.4 Data Register / D
When we edit the program, we used five data register to storage the data. D0 is used to storage the Hex floor and position number. D1 is used to auxiliary calculation of the area judgement. D2 is used to solution of area judgement. If the location is in the Single Area, D2=1, vice versa. D10 is used to storage the DEC Floor number, and D11 is used to storage the DEC position number. More detail is showed on the Table 7-4.
Table 7-4 Data / D Register Definition Detail
Port Application Port Application
D0 HEX Floor Number D10 DEC Floor Number D1 Half of the Floor Number D11 DEC Position Number D2 Single=1, Double=0
7.3
Step Flow Chat
By using Mitsubishi’s PLC, we can separate our program to several steps. And use some trigger conditions to switch steps.
7.3.1 Steps’s Defination
Our system will be separate to 6 steps. They are S1 – Main Step, S2 – Data Receive, S3 – Up Process, S4 – Take In/Out Process, S5 – Down Process and S6 Take In/Out switch Process.
7.3.1.1 Step1 – Main Step
The main step is to check the signal transferred from Single-Chip. In this step, the PLC will keep scanning the input port and reset all useful port until the PLC-IN (X000) get a signal and open. After that, the
7.3.1.2 Step2 – Data Receive
The whole step consists of 3 parts. First, translate data and validation. Second, judge the required location is belong with Single or Double Area. Third, set S3 (Up process). (See Figure 7-2)
When the working step jump to Step 2, it’s also shows that Single-Chip sent 8-digits HEX code to PLC by using port X010 to X017. So we first to storage 8-digits HEX code to register D0. Then we transform it to 8 digits BCD code and storage the 8-digits BCD code to the auxiliary register M20 to M27. After that, we use compare command to judge the validation of the input location number. If the value is not valid, we reset all port and turn back to Step 1. If the value is valid, we then judge it belong to Single Area or Double Area. At the end, we move to Step 3 – Up Process.
Store input BCD
Transform BCD to BIN Data Receive
Data is Valid？ N Reset All Ports & Back Y
Single Area？ N D2 = 0
D2 = 1 Up Process
Y
7.3.1.3 Step 3 – Up Process
In this step, we first to open the Up-Motor until it get the required floor. Then we open the Front-Motor until the lift get the required position. And then move to Step 4 – Take In/Out Process. (See Figure 7-3)
Open Up-Motor Up Process
Get the Floor? N
Y
Open Front-Motor Close Up-Motor
Get the Position? N
Y
7.3.1.4 Step 4 – Take In/Out Process
When the lift reach the required position, the PLC begins to take the boat in/out. First, we use M0 and M1 to judge that the required position is located in Single Area or Double Area. Then, we use M13 and M14 to judge what action we need now. If M0=1and M1=0, give the required position is located in Single Area, and vice versa. If M13=1and M14=0, provides the required action is to take out the boat, and vice versa. (See Figure 7-4)
Figure 7-4 Flow Chat for Step 4 – Take In/Out Process Take In/Out Process
Single Area？ N
Y
Take Out？ N
Single Area
Take Out Single Area Take In
Take Out？ N
Double Area
Take Out Double Area Take In
Finish?
Y Y
Finish? Finish? Finish?
7.3.1.5 Step 5 – Down Process
This process is similar with the Up Process. The different between them is that Up Process use Up and Front Motor, but Down Process use Back and Down Process. (See Figure 7-5)
Open Back-Motor Down Process
Get the Basic
Position? N
Y
Open Down-Motor Close Back-Motor
Get Zero Floor? N
Y
7.3.1.6 Step 6 – Take In/Out Switch Process
In this process, we will switch the take in/out pointer. And judge next step should be jump to Step 3, which means to take in the boat, or finish the whole process. At the beginning of this process, If the M13=1, it means that we just take out but not take in. Then we switch the take in/out pointer M13 and M14. If the M14=1, it means that the whole process is finished. Therefore, the program should feedback the Single-chip and jump to Step 1, which will reset all ports. (See Figure 7-6)
Figure 7-6 Flow Chat for Step 6 – Take In/Out Switch Process Take In/Out
Switch Process
Finish? N Take Out Pointer =1 Take In Pointer =0 Y
Up Process Take In Pointer =1
Take Out Pointer =0
Feedback Single-Chip
7.3.2 Total Step Flow Chat
As we described above, the program consists of 6 steps. They connect each other by some key register or input port. They form the following cycle.
7.3.3 PLC Program
8 Operation Panel
8.1
Operation Panel Requirement
The basic functions of the operation panel is to enter the number of required position and send the position’s HEX code to PLC. For more details, the operation panel should have following functions:
1. Customers could entering the required position; 2. Also control the left manually;
3. The panel can judge that the input value is valid or not by itself; 4. Show the current action. (Entering Number or Manual Control). Therefore, the panel needs include following components:
1. Keyboard. The user can use keyboard to enter the number; 2. Display. Which is used to show the entered number;
3. Lights. The panel could control the left directly if the operation system isn’t working well.
We used Autodesk Inventor to build the model of the operation panel. (See Figure 8-1 )
8.2
Components Design
The components we need are keyboard, display and lights.
8.2.1 Keyboard Design
At first, we consider that how many keys are needed.
First, the valid location number range is 10 to 60 (Decimal number). So we need at least 10 keys ( 0 ~ 9 ) to input required number.
Second, the keyboard needs two keys to confirm the input number or erase the input number. One is ‘Select’ and the other one is ‘Cancel’.
Third, the operation panel include manual control function. Therefore, it needs 4 keys to drive the left directly. The 4 keys are ‘Up’, ‘Down’, ‘Left’ and ‘Right’.
Therefore, we need 10+2+4=16 keys. We can’t provide each key a port, it is wasted. The best method to reduce the port’s quantity is that we can use a 4x4 keyboard. So that the required port’s quantity now is 8 ports. 4 ports for column and 4 ports for row.
8.2.2 Display Design
In our program, we need to display two numbers, one is Floor and the other one is the position. We have two method, one is use two 7-segments, another one is use a two-digits-7-segment. The first one will need 2*8=16 ports. The second on will need 8+2=10 ports. Because we have to save ports for other functions, so we choice method two at the end. (See Figure 8-2)
8.2.3 Light Design
There are four manual control keys, therefore we arranged four lights with corresponding operational name on the operation panel. The light will be illumed when the key is pressed.
8.3
Port Difination
Atmel 89C51 has 4 posts groups (P0, P1, P2, P3). Each group include 8 posts, from 0 to 7. Totally, this single-chip provide 4 x 8 = 32 ports. The definition about all ports are listed on the following table.
Table 8-1 Port Definition
Port Mean Port Mean
P0.0 Display – A P2.0 Row 1 P0.1 Display – B P2.1 Row 2 P0.2 Display – C P2.2 Row 3 P0.3 Display – D P2.3 Row 4 P0.4 Display – E P2.4 Column 1 P0.5 Display – F P2.5 Column 2 P0.6 Display – G P2.6 Column 3 P0.7 Display – DP P2.7 Column 4 P1.0 PLC-Data-b0 P3.0 7-Seg-1 P1.1 PLC-Data-b1 P3.1 7-Seg-2
P1.2 PLC-Data-b2 P3.2 Down Light
8.4
Single-Chip Program
We separate the whole program to 5 parts. They are Main Loop, Number Calculating, Function Processing, Keyboard Processing and Display.
8.4.1 Main Loop
Main Loop, just as its name implies, it is the basic loop of the whole program. This part like the step function in PLC program. The whole loop began at the address 0000H. The necessary parameters (See Table 8-2) will be defined at the first time run.
Table 8-2 The Necessary Parameters Parameter Address Meaning
CEK 02BH or not. Determine whether the keyboard is pressed DEL1 02CH The first delay cycle index.
DEL2 02DH The second delay cycle index.
FLR 02EH Floor number storage.
POS 02FH Position number storage.
TOT 030H Total number storage (Decimalism).
After initialization, the first step is to detect whether the keyboard is pressed or not. The detection is in the subprogram KEY0_1. If key board is pressed, the program will jump to key-processing. If not, the program will go to the display-processing and then jump back to the key detection. The general loop is shown on the following figure. (See Figure 8-4)
8.4.2 Key Detection
For reducing the port’s quantity, we use the 4x4 keyboard. It needs 8 ports, for 4 rows and 4 columns. The connection between keyboard and single chip is showed on the following table. (See Table 8-3)
Table 8-3 Connection Between Single Chip and Keyboard
Port Row Port Column
P2.0 1st P2.4 1st
P2.1 2nd P2.5 2nd
P2.2 3rd P2.6 3rd
Here, we use carry flag to detect whether key is pressed (See Figure 8-5). KEY0_1: MOV A, CEK CJNE A,#0,DISPLAY SETB F0 MOV R2, #0F7H MOV R1, #000H ROW: MOV A, R2 MOV P2, A NOP MOV A ,P2 MOV R5, #04H COLUMN: SETB C RLC A JNC KEY1 INC R1 DJNZ R5,COLUMN MOV A, R2 SETB C RRC A MOV R2, A JC ROW ACALL ZERO RET
Figure 8-5 Keyboard Detection Program More detail is shown on the flow chat. (See Figure 8-6)
Figure 8-6 Key Detection Flow Chat Check Next Column
Pull Down Next Row
Cy=0？ N Y Set Pointer Key Detection N The 4th Column? The 4th Row? N Y
Reset Pointer & Back Key Processing
8.4.3 Key Processing
The keys are separated to 3 parts. First, the Number. Second, Select or Cancel. Third, Manual Control.
8.4.3.1 Number
At first, we use the pointer R7 to judge whether the two digits is completed or not. If not, the program will jump back and wait until next operation. If the number input completed and the key ‘Select’ was pressed, the program will store these number as HEX code in user-defined register ‘TOT’ and judge the validation of these number. If the input number is lower than 10 or bigger than 69, which mean the input number isn’t in the range from 10 to 69, this number is invalid. Therefore, the program will jump to reset program, clear all register and the interface show welcome.
If the input number is valid, the program will keep setting the PLC-IN and sending the HEX code to PLC until the single-chip receive the feedback from PLC-OUT. Here, when the HEX code is sending to the PLC, whole keyboard will be locked. None of the key will be respond until the PLC-OUT send a signal to the single-chip.
8.4.3.2 Select or Cancel
‘Select’ is most important key in the whole keyboard. When this key was pressed, the program will detect the number is input completed or not. If completed, it will go on and began to communicate with PLC. If not, the program will jump back to the main loop and detect next action.
The use of ‘Cancel’ is to erase the imported number. It will not effect when the single-chip is communicating with the PLC. At that time, only PLC-OUT can unlock the keyboard. When the ‘Cancel’ press, the program will erase the register ‘TOT’ and set the display as Welcome interface.
8.4.4 Number Processing
From the method, we use for keyboard, the key position can be defined as following picture. (See Figure 8-7)
15 14 13 12
11 10 09 08
07 06 05 04
03 02 01 00
Figure 8-7 Key Number Location Compare with the key arrangement. (See Figure 8-8)
0 1 2 3
4 5 6 7
8 9 Select Up
Left Right Cancel Down Figure 8-8 Key Arrangement
We found that the sequence of numbers’ key is opposite as the location. Therefore, we need to reverse them. The method we used is the table look-up
method. In the table, we defined it in the reverse arrangement. (See Figure 8-9)
If the key is detected as the number one, the program will use the above method to reverse it. If the key is the functional key, it will jump to the corresponding program. After reverse, the number will go to the validation. For
compare it with the valid range. If the number passed this detection, we will send it to display. If not, the program will be reset.
8.4.5 Display
The display we used is two-digits-Common-anode-7-Seg. Which means we need to edit special program for it. As mentioned above, the location number will be stored in user-defined register ‘TOT’ as HEX code. Therefore, the simplest way is to separate it and storage the high / low digit into two register. After that, we just need to switch and display them. The character with its corresponding code is showed on the following table.
Table 8-4 Characters with Their Codes Character Code Character Code
0 0C0H 8 80H 1 0F9H 9 90H 2 0A4H A 88H 3 0B0H B 83H 4 99H C 0C6H 5 92H _ 0F7H 6 82H H 89H 7 0F8H i 0FBH
RET ; Total 1+50600+2=50603 us =50.603ms Figure 8-10 Delay Time Calculation
8.5
Simulation
The whole program (See Appendix 17) was edited with assembly language. The simulation platform is set up in the software Proteus. Unfortunately, the software didn’t provide PLC. Therefore, we will use lights to simulate the communication between them. The whole wiring diagram of our operation panel is look like following one. (See Figure 8-11)
In the picture, the left eight lights are the simulation of PLC versus single chip communication. The middle one is the 89C51. The mid-under light are the PLC-IN signal. The button near it is PLC-OUT. On the right side, there is a display shows the current action. Under it, there is 4x4 keyboard. On the bottom, there are four indicator light for manual function.
At the beginning, the display shows the welcome interface. (See Figure 8-12)
When the keyboard be pressed, the display will show the number for the floor. The second digit will show the ‘_’ to wait for next operation. (See Figure 8-13)
After that, we can input second number. If we press ‘select’. The single chip will output HEX code for this number from P1.
Here, we use 59 as the example. When we input 59 and pressed ‘select’. The P1 will output decimal number 59’s HEX code 00111011. (The output isn't BCD code, it's HEX code. BIN code for decimal number ‘59’ is 01011001) The high digit of HEX
code corresponds to p1.7. (See Figure 8-14)
Figure 8-12 Welcome Interface
9 Hand calculation and FEM
9.1
Transmission Shaft – Hand Calulation
9.1.1 Fatigue calculation [14]
We know our transmission shaft have a torque on it. So, we can calculate maximum amplitude of the moment 𝑀𝑉 based on exist parameter of shaft.
The material we use for analysis is structure steel [15], 𝑅𝑚 =460MPa
𝑅𝑝0.2=250MPa 𝜎𝑢 = 86.2𝑀𝑃𝑎
According experience formula: 𝜎𝑢 = 0.80𝜎𝑢𝑝
𝜏𝑢𝑣 = 0.58𝜎𝑢𝑝 𝜏𝑢𝑣𝑝 = 𝜏𝑢𝑣 𝜏𝑢𝑣 = 62.49𝑀𝑃𝑎 𝜏𝑢𝑣𝑝= 62.49MPa Surface roughness 𝑅𝑎 = 6𝜇𝑚, ρ = 3mm D=70mm d=60mm
Information above is known, then we can start to calculate, λ=1 (based on not considering manufacturing process)
1
Then, we can calculate maximum amplitude of the moment 𝑀𝑉, 𝜏𝑛𝑜𝑚𝑎 =16𝑀𝑉 𝜋𝑑3 = 𝜏𝑢𝑣𝑝𝑟𝑒𝑑 𝐾𝑓 𝑀𝑉 = 𝜏𝑢𝑣𝑝 𝑟𝑒𝑑 16𝐾𝑓∗ 𝜋𝑑 3 =2012.17 Nm
Compare with our maximum torque 85.48 Nm, it is pretty safe.
9.2
Transmission Shaft – Simulation in software(FEM)
Thankfully, we can use software to simulate it nowadays. It will reduce the time and increase our efficiency. The software we used is ANSYS Workbench 17.2. Which is the most popular FEM analysis software. The criterion we used to judge whether the part/component is failure is Von Mises Criterion.
9.2.1 Von Mises Criterion
At first, we could easily get that the Material we used, Steel 100CrMn6, is a Ductile Material. Therefore, we can’t use Failure Criterion for Brittle Material, which only need to compare the maximal stress with ultimate strength. For Ductile Material, ‘The yielding of ductile materials is mostly due to shear failure.’ [17] Nowadays, there is two mainstream method to judge whether the ductile material is yielding or not. One is Tresca Criterion, anther one is Von Mises Criterion.
For the first one, Tresca Criterion. This method is very simple. It was proposed by Henri Tresca (1814-1885), a French mechanical engineering, in 1864. He propose that the material yields if
σ1− σ3 ≥ σ𝑦
Here, σ1 𝑎𝑛𝑑 σ3 are the maximal principal stress and minimal principal
stress. As we know that, for a certain point, it has three principal stress. But the Tresca Criterion only use two of them. Therefore, it isn't accurate enough. Thankfully, another more sophisticated criterion can help us to predict it more accurately. It is the Von Mises Criterion.
9.2.2 Von Mises Yield Criterion
theory states that the yielding occurs when the deviatoric strain energy density reaches a critical value. [17]After other scientists’ calculation, the whole criterion for linear material can be recomposed to:
𝑤𝑑 ≥ 𝑤𝑦𝑑
Where 𝑤𝑦𝑑 is the deviatoric energy when the material yield in its uniaxial
tension test. [17]But we can’t use it directly to predict the material is yield or not. Therefore, we will do some calculation to regroup the above function. Due to the space limitation, we will not describe how to get the criterion too much. We just use the conclusion which can help use to do the simulation.
After transmission, the function can be expressed in a more concise form:
√1
2[(𝜎1− 𝜎2)2+ (𝜎2− 𝜎3)2+ (𝜎3− 𝜎1)2] ≥ 𝜎𝑦 In ANSYS, it is also referred to as equivalent stress[18],
𝜎𝑒 = √
1
2[(𝜎1− 𝜎2)
2+ (𝜎
2− 𝜎3)2+ (𝜎3− 𝜎1)2]
According to the above conclusion, we will use the software ANSYS Workbench to calculate the Equivalent Stress for the specimen, and compare the conclusion with material yield stress to judge whether it is failure or not.
9.2.3 Analysis Conditions
On the left and right side, there is two bearings to fix and support the shaft. On the left-end and right-end side, there is a bevel gear for each side. One of them connect with motor, and another one connect with up/down shaft. Therefore, we set corresponding boundary conditions on ANSYS Workbench. (See Figure 9-6)
Figure 9-6 Boundary Condition
Here, the cylindrical support we set is fixed radial and axial direction. But release the tangential direction. The force is calculated from the torque. The maximal torque is 84.48 Nm, the radius of the middle point of the support face is 24.707 mm, which equals to applied a 3419.2 N force. The mesh method we used is default. We will change it after get the initial conclusion.
We could find that the maximal stress appears on the place to install the bearing. Therefore, we mesh here more detail. Here, we modified the refinement factor for this area from 1 to 3. It provides more densely notes and elements. After that, the total nodes quantity, which was 506707 at begin, increased to 3110264. The total elements quantity, which was 336174, increased to 2189116. (See Figure 9-8)
Figure 9-8 Refined Mesh on the Fillet
9.3
Transmission Shaft – Compare
We need to compare the shear stress to prove the specimen is safe again. According to the hand calculation, we know that the maximal shear stress under unlimited life times for this material is 𝜏𝑢𝑣𝑝𝑟𝑒𝑑 = 59.40 𝑀𝑃𝑎. The software gives
us the maximal shear stress for the specimen (See Fatigue 9-10). It is 8.1842 MPa. Which is also far smaller than the maximal shear stress. Therefore, we could say that the specimen is safety and could have unlimited life times. (Here, Unlimited life times means the fatigue will not appears before 1,000,000 times cyclic loading.)
Figure 9-10 Shear Stress
9.4
Frame Analysis
Figure 9-11 Boundary Condition of Frame
