Pingfa Feng

Rotary ultrasonic machining of optical K9 glass using compressed air as coolant: a feasibility study

Optical K9 glass has been used in a variety of applications, including optics, electronics, thermodynamics, and fluidics. It has been regarded as a difficult-to-cut material because of its superior mechanical properties. Rotary ultrasonic machining using cutting fluid has been used successfully to machine many different types of brittle materials, such as ceramics, sapphire, and optical K9 glass. Dry machining has been successfully employed in the machining of some materials. However, there are no reported investigations on the rotary ultrasonic machining of optical K9 glass using compressed air as a coolant. This article, for the first time, investigates the rotary ultrasonic machining of optical K9 glass using compressed air as a coolant. The experimental investigations focus on the effects of the input variables (ultrasonic power, spindle speed, and feedrate) on the output variables (edge chipping size, cutting force, surface roughness, and ultrasonic power consumption).

Evaluation systems and methods of enterprise informatization and its application

An efficient evaluation index system and evaluation method for enterprise informatization is critically important for guiding the implementation and development tasks of enterprise information systems. This paper, based on pre-research for a group of typical enterprises and item, factor and reliability analysis of acquired samples, presents a comprehensive evaluation index system which includes three key first-level indicator sets (consisting of the current status of enterprise informatization, the production management characteristics and the system functional requirements), 16 second-level indicators and 80 third-level indicators. According to the characteristics of the designed objectives in the evaluation index system, we propose to use the grey relative correlation analysis method to evaluate the influencing factors of the enterprise informatization, employ the grey comprehensive correlation analysis method to determine the production management characteristics of the enterprise and adopt the grey clustering assessment technology to assess the information system functional requirements based on Grey System Theory. Moreover, case studies for enterprise informatization that mainly focus on the process enterprises in southwest China were illustrated. The research results show that the proposed evaluation system and evaluation method is reliable, practical, and able to better reflect the level of enterprise information and demand characteristics.

Investigations on the critical feed rate guaranteeing the effectiveness of rotary ultrasonic machining.

HighlightsA critical feed rate guaranteeing the effectiveness of RUM was first reported.When the feed rate exceeds its critical value, the cutting force increases abruptly.A model for the critical feed rate was developed.Methods for improving the critical feed rate were proposed. &NA; Rotary ultrasonic machining (RUM) is a well‐known and efficient method for manufacturing holes in brittle materials. RUM is characterized by improved material removal rates, reduced cutting forces and reduced edge chipping sizes at the hole exit. The aim of this study is to investigate the critical feed rate to guarantee the effectiveness of RUM. Experimental results on quartz glass and sapphire specimens show that when the feed rate exceeds a critical value, the cutting force increases abruptly, accompanied by a significant decrease of ultrasonic amplitude. An analytical model for the prediction of critical feed rates is presented, based on indentation fracture mechanic and the theory of impact of vibrating systems. This model establishes the theoretical relationships between the critical feed rate, idling resonant ultrasonic amplitude and spindle speed. The results predicted by the analytical model were in good agreement with the experimental results.

Rotary Ultrasonic Machining of Sapphire: Feasibility Study and Designed Experiments

Sapphire, widely used in high-speed integrated-circuit chips, thin-film substrates, and various electronic components, is regarded as one of the most difficult to cut materials owing to its great hardness and low fracture toughness. Rotary ultrasonic machining (RUM) has been regarded as an effective processing method for hard and brittle materials. In this paper, RUM process is introduced into the drilling of sapphire for the first time. The feasibility to machine sapphire using RUM is studied. Moreover, results of a designed experimental study into RUM of sapphire are presented to discuss the main effects as well as interaction effects of process parameters (ultrasonic power, spindle speed, and feedrate) on outputs. The process outputs investigated include cutting force and edge chipping size.

An identification method for key geometric errors of machine tool based on matrix differential and experimental test

This paper presents a key geometric errors identification method for machine tools based on matrix differential and experimental test. An error model for a machine tool was established by regarding the three-axis machining center as a multi-body system. The sensitivity coefficients of the machining error with respect to the geometric errors were determined using the matrix differential method, and the degree of influence of the geometric errors on the machining accuracy under ideal conditions was discussed. Using the 12-line method, 21 geometric errors of the machine tool were identified, allowing the three-dimensional volumetric error distributions of the machine tool to be mapped. Experimental results allow the degree of influence of the geometric errors on the machining accuracy under actual conditions to be confirmed. Finally, the key geometric errors affecting the machining accuracy were identified by a combination of matrix differential and experimental test. This paper provides guidance for the machine tool configuration design, machining technology determination, and geometric error compensation.

Experimental Investigation on Surface Roughness of KDP Crystal Pro-Cessed with Rotary Ultrasonic Face Milling

KDP crystal is a good nonlinear optical and electro-optical crystal material. However, KDP crystal is considered to be one of the most difficult machining materials due to its inherent properties. This paper presents a preliminary experimental study on surface roughness of KDP crystal processed with rotary ultrasonic face milling. The study shows that the process variables (spindle speed, feedrate, and milling depth) have significant influence on the surface roughness in processing KDP crystal. It discusses the effects of the mechanical properties of KDP crystal on the processing performance. The experimental investigation reveals that the rotary ultrasonic face milling method can obtain smoother surface, which means the method is available for processing KDP crystals with a proper machining conditions. This preliminary research affords a guiding significance for precision processing KDP crystals.

An improved production planning method for process industries

An effective production planning method plays a key role in the production management system for the process manufacturing industries. It is particularly important to develop ways to solve the problems under demand uncertainty, planning inadequacy and capability unbalance. In this article, we present a process industries oriented production planning optimisation method that focuses on minimising inventory costs, and optimising production load rate and balance load rate. By analysing the demand forecasts model and minimum inventory costs control model, we propose how to achieve total production demand amounts in correlation with production orders. We also discuss the Weibull distribution-obeyed equipment repair model to maximise the equipment utilisation rate. The equipment repair time is also considered when specifying the production lead time. The production planning system optimisation objectives function is given, in the condition of the equipment production capacity model and the smallest economic batch requirement. To validate the proposed methods, real production and sales data are sampled from a pharmaceutical plant. The case study shows that the improved production planning models are more targeted and effective for Chinese process industries.

On the Analysis of Force Transmission Performance for the Thrust Systems of Shield Tunneling Machines

Earth pressure balance is normally used in excavating tunneling due to high automation, quick construction, environmental friendliness, etc. Based on minimum mean square error, optimized mechanical models for non-group and group thrust systems of the earth pressure balance have been constructed. Through the offset load, the force transmission performances for the two thrust systems were studied, respectively. By applying force ellipse to the thrust system of a shield machine, the difference between the two configurations was analyzed. It provides an important theoretical foundation for the development and design of thrust systems.

An Experimental Study on Processing Performance of Rotary Ultrasonic Drilling of K9 Glass

Rotary ultrasonic machining process, regarded as one of the effective processing methods for hard-brittle materials, is introduced into drilling K9 glass in this paper. The effective cutting velocity, cutting depth, and cutting length of single diamond particle are determined by analyzing the kinematics characteristic of diamond tool in rotary ultrasonic drilling (RUD). Experiments are conducted to study the influences of process variables (spindle speed, feedrate) on cutting force, chipping size, and surface roughness in RUD. As comparison study, the processing performances between RUD and diamond drilling are also discussed. The experimental results show that the RUD process can significantly reduce cutting force and the value of chippings size, which inferred that RUD process can improve machining efficiency and make the machining cost lower. It is also concluded that the effective cutting depth of diamond particles is the main factor for surface roughness in RUD of K9 glass.

Experimental Investigation of Rotary Ultrasonic Face Milling of K9 Glass

K9 glass is regarded as one of the most difficult-to-machine materials due to its mechanical characteristics, which is known as an excellent performance optical material. In this paper, rotary ultrasonic face milling (RUFM) process is introduced into machining flat surface of K9 glass using right-angle diamond cutter for the first time. It studies the influence of process variables (spindle speed, feedrate, cutting depth, and cutting width) on cutting force and surface roughness through the single-factor experiments. The cutting force is measured by a KISTLER dynamometer, and the surface roughness is measured by a talysurf. The investigation also includes a comparison between RUFM and diamond milling. The experimental results tell that the RUFM process can significantly reduce cutting force, which inferred that RUFM can have less tool wear and longer tool life. It also shows that the surface roughness in RUFM of K9 glass is slightly higher than that obtained in diamond milling.