@phdthesis{oai:sucra.repo.nii.ac.jp:00010371,
 author = {Burdukovskyi, Ivan},
 month = {},
 note = {76 p., In recent years, the miniaturization of the nozzles in the gas turbines for the thermal power stations or in the marine diesel engines has been required to cope with the technological innovations of the high-pressure fuel injection. Therefore, it is considered that diameter of future holes in the nozzles must be reduced to 0.2 mm or below from the current value of 1.0 mm. The aim of the previous study was improvement of micro deep drilling at hard materials (such as Stellite, Hastelloy or SUS304), which hole diameter is 0.2 mm or below and an aspect ratio (Lh/dh) of 20 or above. The micro deep drilling of hard materials is required including of step feed in the process that increases machining time. To decrease the machining time by increasing the step feed while maintaining tool life, two methods had been proposed. Increasing of the step feed is providing by reducing of cutting force. The first method reduces the cutting force by applying of the ultrasonic vibration in the micro drilling by oscillation of the tool (frequency ～40 kHz, amplitude ～1 μm). The second method also reduces the cutting force by applying of low frequency vibration in the micro drilling by oscillation of workpiece (frequency ～150..250 Hz, amplitude ～10 μm). Each method can improve the drilling process independently because of different vibration parameters by frequency (～40 kHz and ～200 Hz) and amplitude (1 μm and 10 μm). Presence of two types of vibrations makes requirement of different way including its to the drilling process (oscillating of the tool and the workpiece).
The nozzle has a curved shape in place for the drilling that means processing of the 2-axis drilling. To cope with the drilling process assisted by low-frequency vibration of curved surface, we have developed fixing system for 2-dimensional vibration. The fixing system for 2-dimensional vibration (FS2DV) consists of horizontal and vertical vibration sources with spring systems along directions of the sources. We select voice coil actuator (VCA) for using as the vibration source to supply enough of power for oscillation the workpiece with one spring system and connecting parts. The direction and value of the 2-dimensional vibration is passively controlled by amplitude ratio and values of the vibrations from the vertical and horizontal sources. The spring systems have variable rigidities for using of the FS2DV with different vibration frequency. The vertical spring system consists of number of plates (made of spring steel), which are fixed between internal and external collars. Rigidity of the vertical spring system is varied by changing number and shape of the spring plates. The horizontal spring system consists of three sets with belleville springs located at 120º relatively to each other, which are fastened on the external collar of the vertical spring system. Rigidity of the horizontal spring system is varied by changing number and assembling combination of the belleville springs.
Thrust force (6…10N) from drilling process induces unintended displacement of the workpiece. Depending on unbalancing between rigidities of the vertical and horizontal systems, unintended displacement may create hole diameter error. Setting of the spring systems with balanced rigidities can minimize influence of the unintended displacement on the hole diameter error. Analysis of the vertical and horizontal spring systems was made for successful using of the FS2DV during 2-axis micro deep drilling process assisted by low frequency vibration. Based on this analysis, the setting requirements of the FS2DV have been proposed for particulars vibration frequencies.
The FS2DV have been verified for controlling vibration under loading force (which imitate the axial force of drilling) with different angles (15°, 45°, 75°) or frequency (149.5 Hz, 198.0 Hz, 252.3 Hz). Rigidities of the spring systems were adjusted with values that they satisfy to mention above requirements for each frequency (800 kN/m, 1050 kN/m, 1600 kN/m). Resultant vibration was measured by laser sensor of displacement in vertical and horizontal directions. The analysis of the experimental results has been made. The total hole diameter error can be 2.1…3.7 μm (depending on vibration frequency and direction), but it is not big compering with 6 μm, which is a standard hole’s tolerance with diameter 0.2 mm.
At the final, we observe the deviation of the thrust force during vibration process, because the thrust force is important parameter of the drilling. The trust force may enlarge the temperature of drill’s edge or initiate breakage of the drill. So the thrust force measuring is made during vibration process with frequency 198.0 Hz, amplitude 10 μm and direction 45º. The thrust force deviation is present during the vibration process. It is up to 1.3 N with the frequency of workpiec’s vibration and 0.4 N with frequency about 1200 Hz. The thrust force is not big relatively to the value of thrust force of the drilling at the study of Dr. Nanbu (9 N).
From experimental and analytical study, we obtain the following conclusions:
It was proposed concept for passive controlling of the vibration. It consists in passive controlling of two the independent vibrations in the vertical and horizontal direction.
The fixing system of 2-dimensional vibration (FS2DV) has been designed for fulfilling this concept. The FS2DV consist of the vertical and horizontal voice coil actuators with spring systems along action of each actuator.
We have the developed FS2DV with usage range frequency of 150…250 Hz, amplitude 10 μm. The system can be properly used with cutting force (up to 10 N) and any angle (from 0 to 90°) by selecting appropriate rigidities for the vertical and horizontal spring systems.
Finally, we observe the deviation of the thrust force. The trust force is deviating during the vibration process with amplitude up to 1.3 N and frequency of the workpiece’s vibration., Chapter 1 ............................................................................................................................. 8
Background ................................................................................................................. 8
1.1. Micro-deep drilling of hard materials ...................................................................8
1.2. Method of drilling assisted by vibrations(3), (7) ......................................................9
1.3. Method assisted by low frequency vibration(7) ...................................................10
Chapter 2 ........................................................................................................................... 13
Objective of study ..................................................................................................... 13
Chapter 3 ........................................................................................................................... 15
Fixing system for 2-dimensional vibration (FS2DV) ................................................ 15
3.1. Oscillating by voice coil actuator .......................................................................15
3.2. Design of FS2DV ................................................................................................16
3.3. Vertical and horizontal spring systems ...............................................................17
3.4. Setting of the spring systems ..............................................................................20
3.5. Phase difference correction .................................................................................23
Chapter 4 ........................................................................................................................... 24
Vibration controlling ................................................................................................. 24
4.1. Experimental setup ..............................................................................................24
4.2. Controlling of vibration ......................................................................................25
Chapter 5 ........................................................................................................................... 27
Deviation of thrust force during vibration process .................................................... 27
5.1. Experimental setup ..............................................................................................27
5.2. Observing of the thrust force deviation ..............................................................28
Conclusion ........................................................................................................................ 31
Nomenclature .................................................................................................................... 32
References ......................................................................................................................... 33
Appendix A. Design of fixing system for 2-dimensional vibration.................................. 35
Appendix B. Controlled 2-dimensional vibration ............................................................. 70
Appendix B. Manual for FS2DV ...................................................................................... 77, 指導教員 : 堀尾健一郎, text, application/pdf},
 school = {埼玉大学},
 title = {DEVELOPMENT OF FIXING SYSTEM WITH 2-AXIS LOW FREQUENCY VIBRATION FOR MICRO DEEP DRILLING},
 year = {2015},
 yomi = {ボルヅゥコヴスキ, イヴァン}
}