臺灣博碩士論文加值系統

Cutting forces in machining operation are of great importance. There is a need to measure these forces by a simple and low cost solution. The present work covers the design and construction of a sensor to measure cutting forces generated in turning with a CNC lathe by attaching strain gauges directly inside of the tool holder, one on each side of the rectangular shank, to measure strain and estimate these forces.
The design and implementation of the sensor consisted of three parts: The tool holder modification to attach the strain gauges, where a static analysis was done to find the best location to place them. The signal conditioning part in which a PCB was fabricated. This PCB holds the circuit for acquiring the signal and consists of a ½ Wheatstone bridge, an amplification stage, and a filter and offset stage. The third part is the data acquisition, where a NI cDAQ 9171 with an analog input module 9215 was used to capture the conditioned signal into the PC.

Cutting forces in machining operation are of great importance. There is a need to measure these forces by a simple and low cost solution. The present work covers the design and construction of a sensor to measure cutting forces generated in turning with a CNC lathe by attaching strain gauges directly inside of the tool holder, one on each side of the rectangular shank, to measure strain and estimate these forces.
The design and implementation of the sensor consisted of three parts: The tool holder modification to attach the strain gauges, where a static analysis was done to find the best location to place them. The signal conditioning part in which a PCB was fabricated. This PCB holds the circuit for acquiring the signal and consists of a ½ Wheatstone bridge, an amplification stage, and a filter and offset stage. The third part is the data acquisition, where a NI cDAQ 9171 with an analog input module 9215 was used to capture the conditioned signal into the PC.

Abstract i
Acknowledgements ii
Table of Contents iii
List of Figures vi
List of Tables viii
Chapter 1 Introduction 1
1.1. Research motivation 1
1.2. Objectives and research scope 1
1.3. Overview of related researches 2
1.4. Thesis contribution 3
1.5. Thesis structure 3
Chapter 2 Hardware Design 4
2.1. Cutting forces 4
2.2. Tool holder modification 5
2.3. Static analysis 5
2.3.1. Simulations using CAD/CAE software 6
2.3.2. Force position comparison 9
2.4. Strain gauge bonding 9
2.5. System protective coating and considerations 11
Chapter 3 Signal Conditioning 13
3.1. Description 13
3.2. Wheatstone bridge 13
3.2.1. Quarter bridge (one active strain gauge) 14
3.2.2. Half bridge (two active strain gauges) 15
3.2.3. Input connector 16
3.2.4. Special considerations about bridge selection 17
3.3. Amplification stage 17
3.4. Filter and offset stage 19
3.4.1. Active filter stage 19
3.4.2. Offset stage 20
3.4.3. Output connector 22
3.5. PCB layout 24
3.6. Noise and drift tests 25
Chapter 4 Calibration 27
4.1. Experimental setup 27
4.1.1. Weight measuring for calibration 28
4.1.2. Optimal connections for calibration 29
4.2. Calibration process 31
4.2.1. Tangential force data acquisition 33
4.2.2. Feed force data acquisition 34
4.3. Data analysis 34
4.4. Sensor characteristics 37
Chapter 5 Experimental Results 38
5.1. Cutting tests description 38
5.2. Experimental setup 38
5.3. Cutting tests results 40
5.3.1. Workpiece diameter reduction using TB-20YBC 40
5.3.2. Workpiece diameter reduction using iTC-2000 45
5.3.3. Cutting of a workpiece sample 49
5.4. Analysis and discussion 51
Chapter 6 Conclusions 53
References 55
Appendix 56
A. Tool holder technical drawing 56

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