Abstract: Influence of the cutter rake angle to the surface quality of crystal KDP is analyzed
theoretically in this paper. Analysis result shows that the tension stress reaches minimum in the
crystal KDP cutting region and optimal value of the surface quality is obtained as cutter rake angle
is about -45°. Cutting experimental of different cutter rake angle is realized on the machine tool.
Experimental results show that the surface roughness of the crystal KDP reach minimum (rms is
6.521nm, Ra is 5.151nm) as the cutter rake angle is about -45°, this experiment certifies the
correctness of this theory analysis. Theory analysis and experimental results show that influence of
the cutter rake angle to surface quality of the crystal KDP is very large, for ultra-precision
machining of the crystal KDP, when large negative rake diamond cutter (-45°) is adopted, the
super-smooth surface can be obtained.
Abstract: This paper deals with the milling machinability of gamma titanium aluminide at speeds
of 60-240m/min. The results showed that surface roughness was less than Ra0.44μm at all cutting
speeds used in the tests even when the tool wear reached VB0.2mm. The milling forces increased
slightly with increasing cutting speed but increased rapidly with the elevated flank wear value
especially for the Fy component. Compared to those of titanium alloy TA15, the milling forces of
γ-TiAl were 190%, 180% and 200% greater for Fx, Fy and Fz respectively under the same
machining conditions. Workpiece surface has a maximum microhardness of approximately
600HV0.100, and the depth of maximum hardened layer was confined to 180μm below the surface.
When cut with TiAlN coated carbide tool, tool life was 35 min which was only about 1/2 of that for
titanium alloy TA15.
Abstract: Quartz has excellent optical properties and thus it is often used as the material of mirror
and lens. However, it is almost impossible to be machined by cutting due to its brittle and high
hardness. Grinding is a common method for machining quartz. One of the authors designed a new
type of a paraboloidal mirror of quartz for the neutron optical devices. The fabrication process of
this mirror was investigated in this experiment. A jig with two grooves of 90 degrees was made and
two workpieces were stuck on the jig using the wax melt at about 60 degrees centigrade. The two
workpieces were first ground applying ELID (electrolytic in-process dressing) grinding method
with #325 and #1200 cast iron bonding diamond abrasive wheels. Then the ground surface was
polished with CeO2 slurry. The finished surface roughness was Ra2.0nm and rms2.4nm and its form
error about 2μm. After coating process, its properties of focusing neutron beam were measured. The
results were that the reflecting rate was 42%, gain 1.9 and 2.3mm×10.1mm beam focused to
Abstract: Delamination is one of the most concern defects in drilling of composite material.
Delamination depends on the factors such as feed rate, tool geometry and wear. The mechanics of
drilling composite materials has been examined along with the quality of the hole and the effect of
tool design parameters. The capacity of computerized tomography (CT) showing sample
cross-section in a nondestructive way made it successful in measuring the drilling-induced
delamination. In the experiment, the correlation between thrust force and the measured
delamination extent in use of twist drill and core drill is illustrated and compared with the known
ultrasonic C-scan. It is compared with the ultrasonic technique and is demonstrated a feasible and
an effective tool for the evaluation of drilling-induced delamination.
Abstract: In this paper, a novel spinning-inflated-ballonet polishing tool for curved surface of
mould is proposed. The head of the tool is a spherical spinning-inflated-ballonet whose inner air
pressure can be controlled on-line and the head surface is covered with a suitable polishing cloth.
The head can be rotated in high speed driven by an electromotor or high pressure airflow and its
rotating speed can be adjusted. The flexibility of the head, the polishing force in radial direction and
the contact area between the head surface and the curved surface of the work-piece can be
controlled by adjusting the feeding deepness and ballonet pressure of the tool. The structure and the
polishing mechanism of the novel polishing tool are introduced. The application of robot polishing
system based on the novel polishing tool also is discussed. Finally the polishing control strategy of
curved surface is researched.
Abstract: Considering the key technologies to enhance the accuracy of micro-EDM, a micro-EDM
system and some techniques are researched. In this system, a micro-energy pulse power supply
whose open voltage and capacitance can be adjusted is developed. The detection and control
subsystem of the machining process is designed and applied. A simple method of machining high
precision microelectrodes is adopted. The forming mechanism of the gap in EDM process is
analyzed theoretically. The processing experiments are carried out on the system, and the results
basically coincide with the theoretical analysis. The experimental results of machining
microelectrodes and micro holes show that the Ø4.5±0.5μm microelectrodes can be ground, and the
Ø6±2.0μm micro holes can be drilled.
Abstract: A new micro EDM method is described. First, the basic principles of micro EDD are
analyzed and realized conditions are predicted. Then with an ordinary EDM shaping machine and
electrode brass, steel and tungsten, a large number of experiments are carried out in air to obtain the
effects of different processing parameters on micro EDD. A micro cylinder with 0.19mm in
diameter and 7.35mm in height is formed on high-speed steel surface. By exchanging the polarities
of electrode and workpiece the deposited material can be removed selectively, thus the reversible
machining is realized. In the end, measurements show that the deposited material is compact and
hardened, whose components depend on the tool electrode material although Zn in brass electrode
is oxidized to ZnO.
Abstract: This paper describes the vacuum-compatible air bearing designed with a cascaded
exhaust scheme to minimize the leakage of air in a vacuum environment. The design of the air
bearing, including the differential exhaust system, required great care because several design
parameters, such as the number of exhaust stages, diameter and length of the exhaust tube, pumping
speed and ultimate pressure of the vacuum pump, and seal length and gap greatly influenced the
leakage of air and thus the degree of vacuum. A leakage analysis was performed to estimate the
chamber pressure and an optimization method based on the genetic algorithm was proposed under
several constraint conditions. The results showed that the degree of vacuum improved dramatically
compared to the initial design, and that the distribution of the spatial design parameters and
technical limit of the pumping speed were well achieved.