Abstract: In this paper a dynamic non-linear mathematics model is proposed to predict the surface
roughness in optical ultra-precision machining, which can be automatically built by evoling
computer program of genetic algorithm. The new model can improve the fitting and predicting
accuracy, compared with the traditional linear regression model. The numerical simulation test
proves the effectiveness and accuracy of new model.
Abstract: Prediction of temperature field is a key technology to achieve the groove design and
reconstruction of milling insert, predictive model of neural network is a new way to achieve the
prediction of temperature field. According to the non-steady state characteristic of temperature field
of milling insert, the paper puts forward a predictive model of temperature field of milling insert
with 3D complex groove based on Levenberg-Marquardt algorithm of BP neural network, and it
overcomes the disadvantage that traditional neural network is easy to fall into local minimum. The
predictive results show that this predictive model can converge quickly and predict accurately.
Abstract: Digital action mechanism of machining error propagation has been a hot research topic in
recent years. A complicated machining system usually contains multiple stages. Basing on
analyzing digital behaviors of machining process flow, a methodology of machining error
monitoring and control is put forward, which is based on dynamic programming. Under this
framework, state of machining feature is described with vector matrices, and then differential
transition matrices are used to represent the influences of error sources on machining feature quality
of workpiece. Basing on this, a general error propagation equation is derived. At last, an example of
a three-stage machining processes is presented to illustrate the proposed methodology.
Abstract: A new optical manufacturing technology called bonnet polishing has been developed
over last decade. During bonnet polishing, the puffed bonnet is flexible and self-reacting against the
surface configuration of optical parts. So the same polishing tool can be used in machining the
optical parts with different curvature. The mechanism of the bonnet polishing is described in this
paper firstly. Since the optical workpiece has been polished in the “polishing spot”, the bonnet
polishing experiments have been accomplished on the trial-manufacturing machine to study the
effect of technological parameters on the size and shape of “polishing spot” and the material
removal rate of optical workpiece. At last, the material removal rules of the bonnet polishing have
been given in the paper.
Abstract: Laser forming is a technique of using the energy from a laser beam to modify and adjust
the curvature of sheet metals or hard materials. 2-dimention (2D) laser forming can reasonably
accurately control bend angles with various materials. To advance this process further for realistic
forming applications in a manufacturing industry, it is necessary to consider larger scale controlled
3-dimention (3D) laser forming. On the base of mechanism of 2D laser forming, the deformation
mainly depends on the temperature gradient between upper and bottom surface of sheet metal. The
work presented in this paper shows that the temperature field of using the spider scanning path to
transform the thin square sheet to spherical dome by 3D laser forming. The explicit thermal analysis
on 3D laser forming is shown in the article. This paper discusses the interaction between moving
laser beam and sheet, the varied temperature field on the sheet during laser scanning. In order to
give the verification on the results of simulation, the correlative experiment has progressed and the
results of experiments are in accord with the simulation.
Abstract: Effects of addition of glycerin in the electrolyte on the micro arc oxidation process have
been investigated with a bipolar asymmetric pulse power supply, which involves peak value of
pulse current, voltage, thickness and hardness of ceramic films of AZ61 magnesium alloy as well as
surface roughness and structures. The results reveal that addition of a proper amount of glycerin
helps to the decrease of positive pulse current peak and voltage, formation of a much dense ceramic
coating with increase of the hardness, decrease of the surface roughness and good crystallization.
When the amount of glycerin is more than 10ml/l, the growth of ceramic coatings begins to be
inhibited and the performance of ceramic coatings seriously turns worse.
Abstract: Three dimension indenter model was established to replace the ideal shape indenter
model in the study of nano-indentation simulation. The limitation of short of comparing to actual
condition can be solved. Single crystal aluminum surface nano-indentation on the condition of arc
indenter is researched by molecular dynamic simulation. The influences of different arc radius of
indenter head to testing results are discussed and compared to experiment results. The results show
that The measured hardness value increases with indenter head arc radius on the same indentation
depth condition. With the increase of indentation depth, the difference between measured results
with changed indenter head arc radius reduces gradually. When the indentation depth increase to a
certain value, the arc effect of indenter head could be ignored, the measurement will be invariable.
Abstract: In the paper, the experimental study of grinding process of 2024Al/SiCp composites with
the electroplated diamond wheel was conducted. The results indicate that the surface roughness of
the workpiece is between 0.554 μm and 1.2 μm. Increment of the spindle speed, reduction of the cut
depth and decrease of the feed speed make the surface roughness value reduce. After grinding,
compressive stresses on the machined surface can be obtained. During grinding, the normal
grinding force is greater than the tangent force and the grinding forces increase as the increase of
the feed speed and depth of cut.
Abstract: Assembly sequences can be represented by a Petri net(PN) which characterizes dynamic
system changes and provides a tool for obtaining optimal assembly sequences. In this study some
assembly operation constraints are considered in order to obtain more practical sequences which are
conformed to real situations. In order to enhancing the efficiency of the assembly sequence
planning, knowledge-based Petri net, combining an usual Petri net with expert’s knowledge and
experiences, is proposed to construct the assembly model. With the complexity of the product, the
product’s assembly model size will be too large to analysis. So the basic subnets are used to reduce
the large PN. And the reduced version can be used for the analysis of the original PN. To verify the
validity and efficiency of the approach, a variety of assemblies including some complicated
products from industry are tested, and the corresponding results are also presented.
Abstract: A design process of PMT virtual conceptual design is put forward, and a design platform
of PKM virtual prototype is developed based on ADAMS; By analyzing topological structure and
classifying the functional module of the existing PMTs, a modular component base are built. The
management of component base and virtual assembly of PMT are realized. A method to analyze
kinematic properties of parallel mechanism is introduced by taking screw theory as guidance and
taking virtual prototype technology as verifying tool. With the method, DOFs of parallel mechanism
are vividly depicted and rationalities of actuation scheme are judged.