Machine Tool Bed Research Articles

Performance Evaluation of Cryogenically Treated Tungsten Carbide Insert on Face Milling of Grey Cast Iron

The objective of this study is to evaluate the wear progression of cryogenically treated and untreated tungsten carbide inserts during face milling of Grey Cast Iron which is a commonly used material in machine tool beds and automotive components due to low cost, high vibration damping capability, and easiness of manufacturing. Commercially available uncoated Tungsten Carbide insert with around 6% Cobalt (Co) content were selected for the study and flank wear and nose wear were taken as the performance evaluation criteria. The results show that the cryogenically treated samples have better wear resistance than the untreated inserts which could be ascribed to the martensitic phase transformation of Co from α-Co (FCC) to ε-Co (HCP) during the cryogenic treatment.

Effect of glass fiber surface treatment on the mechanical strength of glass fiber reinforced resin mineral composite for machine tool bed

With excellent vibration alleviating properties, resin mineral composite (RMC) has attracted special attention in the field of mechanical engineering. However, applications of RMC are restricted because of its limited mechanical strength. In this research, the glass fiber (GF) was added into RMC to increase its mechanical strength, and the effect of the length and mass fraction of GF on the mechanical strength of GF/RMC were investigated. Results showed that the compressive strength and flexural strength of RMC first increased and then decreased as the length and mass fraction of GF increased. In order to improve the interfacial bonding between GF and RMC, the GF was subsequently treated by ultrasonication, oxidation, and silanization. And three types of treated GF, i.e., ultrasonic treated GF (U-GF), ultrasonic and oxidation treated GF (O-GF), and ultrasonic, oxidation and silanization treated GF (S-GF) were obtained. Among these three types of treated GF, the S-GF exhibited superior reinforcement in RMC. In addition, the effect of oxidation parameters on the mechanical strength of S-GF/RMC was investigated. In the case of sodium hydroxide oxidation, the optimum mechanical strength of S-GF/RMC was achieved when the S-GF was treated in 1.5 mol/L sodium hydroxide for 3 h at 40°C, in which the compressive strength and flexural strength of S-GF/RMC increase by 17.5% and 20.8% compared to neat RMC, respectively. In the case of hydrogen nitrate oxidation, the best mechanical strength of S-GF/RMC was achieved when the S-GF was treated in 1.5 mol/L hydrogen nitrate for 5 h at 80°C, in which the compressive strength and flexural strength of S-GF/RMC increased by 11.2% and 18.1% compared to neat RMC, respectively. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Bionic design and verification of high-precision machine tool structures

Highly stiff and lightweight machine tool structures are very important for improving machining accuracy. How to reasonably arrange stiffeners is one of the problems that designers must solve to achieve required structural performances. This paper presents a practical approach for stiffener layout design, which is inspired by the adaptive growth phenomenon observed in nature. Firstly, a mathematical model is built to provide theoretical basis for the adaptive growth of stiffeners to the applied load. Then a corresponding algorithm is developed to realize the generation of stiffener layout, during which the growth rates are determined by the generalized heights of stiffeners and the growth directions by branching and degenerating operations. When applying the approach to redesign an actual machine tool bed structure, a simple spring model is introduced, which can greatly reduce computation cost by transforming the 3D stiffener layout design problem into a 2D one. Numerical and experimental results show the stiffness enhancement, and thus, the applicability and validity of the approach are proved.

Structural Design of Machine Tool Bed Based on Dynamic ANSYS

This paper attempts to use a simple and practical method based on the finite element theory for the optimal structural design of machine tool bed. The higher is the natural frequency of structure, the better are static and dynamic structural stiffness. Dynamics finite element model of CA6136 machine tool bed has been established with the finite element analytic technique in order to improve the dynamic characteristics. Then, two improved bed design schemes based on unit structure (US) are presented and analyzed by comparison using natural frequency and the total mass of structure as target. The simulation results indicate that the method is simple, effective and feasible. The method also can be applied to other dynamic structural design.

Modal Analysis of Artificial Granite Grinding Machine Tool Bed

Machine tool bed, which supports headstock, tailstock and other functional components, is one of the important structure parts of machine tools. Precision grinding machine tool beds are designed by the authors with artificial granite and cast iron respectively for research. Their three-dimensional models were established via software SOLIDWORKS and then imported into the finite element software (ANSYS) to simulate for the first eight modal frequencies and the corresponding vibration modes. Simulation results show that the first eight order natural frequencies of artificial granite bed are better and the corresponding maximum amplitude of vibration modes are decreased significantly than cast iron bed. The dynamical properties of artificial granite bed are obviously better than grey cast iron bed.

Modal Analysis of the Bed Structure of Large Diameter Fresnel Lens Mold Machine Tool

Modeling of the large diameter Fresnel lens mold machine tool bed using 3D software solid works, and then import the ANSYS Workbench, natural frequencies and modal shapes are obtained by the study of the modal analysis and analysis of the structure characteristics of the machine bed, for the next step on the bed structure optimized to provide a reliable theoretical basis. Keywords: the bed; ANSYS Workbench; modal analysis; natural frequencies

Finite Element Analysis and Optimization of Thermal Deformation of Resin Concrete Manufacturing Bases

Resin concrete generally has good mechanical properties, excellent thermal stability and great vibration resistance, the model of the ultra-precision machining center bed is established to study the thermal stability of the resin concrete using virtual reality and collaborative simulation technology based on Pro/E and ANSYS Workbench. The main factors that affect the machine tool bed thermal deformation were found through analyzing the deformation results and the materials and restrain conditions were optimized. The results proved that the optimized machine tool bed has good thermal stability and theoretical basis was provided to improve the thermal stability of the ultra-precision machining centers.

Current Research and Development Trends of Micro Machine Tool for Micro-cutting

Micro-cutting technology which has a unique advantage in 3D complex parts processing is a hot spot to precision and ultra-precision manufacturing technology research. Micro-cutting machine tool as an important part in micro-cutting technology has presented a miniaturized trend and became an emphasis in current research of micro manufacturing equipment. The research status of micro machine tool for micro-cutting are systematically summarized from the aspects of machine tool bed, micro spindle unit, feed table, micro cutting tools, NC system and monitoring system. Some key technology problems are analyzed such as miniaturized machine tool bed, high speed and high rotation accuracy of micro spindle, high precision and fast response of micro table, structure and performance of micro cutting tool, openness and high precision interpolation of NC system, visual monitoring of machining process, performance of machine tool and so on. Meanwhile, feasible countermeasures toward mentioned problems are presented. The development trend of micro machine tool for micro-cutting is forecasted.

Design of Automatic Scraping System

Based on the principle of hand scraping a set of automatic scraping system is designed in this paper. Machine tool bed consists of supporting chassis and cast iron sidewall, which has little deformation, good rigidity and high mechanical strength. And the operating floor features 3-Degree of Freedom with high precision. Guideway adopts imported linear guideway, featuring high precision, high load - bearing redundancy and long life. Scraping tool holder is stably installed in the hole at the end of the piston rod. By the electrical control system the cylinder can control scraping tool to do reciprocal motion stably. Scraping points on the surface of workpieces are captured by a CCD camera with high detection efficiency and accurate test data. The results show that the system is designed to greatly reduce labor intensity and improve scraping efficiency under the precondition of keeping good scraping quality.

Forming process and damping properties of carbon fiber-reinforced polymer concrete

Carbon fiber-reinforced polymer concrete has good damping property that can be used to produce machine tool beds, spindle boxes, and some other basic mechanical components in order to better satisfy the requirement of high-speed and high-precision machining accuracy. In order to get the influence of different components, the damping model is built on the basis of energy dissipation theory and the damping loss factor is defined as a new parameter to characterize the damping property. Typical samples are prepared and single factor experiments of fiber length, fiber dosage, coal ash’s usage, and different surface treatment of carbon fibers are used to validate the aforementioned assumptions. Research results show that the coal ash used in carbon fiber-reinforced polymer concrete plays an important role in enhancing damping. A weak interface bonding condition can get a better damping performance than a strong one. The best damping performance is consistent with reasonable fiber length and its dosage.

Thermal Characteristics Analysis of Nuclear Power CNC Wheel Groove Milling Machine Based on Finite Element

For nuclear power CNC wheel groove milling machine in the work under the influence of a variety of heat sources, establish the finite element model of machine, using finite element analysis software ANSYS, analysis and thermal-structure coupling of heat source in the processing state mechanism, thermal key points out machine, the effect of deformation on the machine geometric accuracy evaluation of heat, and the machine thermal optimization analysis of corresponding, deformation of machine in the three direction. The results show that: the machine in machining spindle heat is an important factor affecting the machining accuracy of machine tools, and heat through various ways to machine tool bed, causing warping, guide rail bending, through this analysis provides reference for analysis and optimization design for the machine tool thermal deformation.

The Improved Design of Machine Tool Structure Based on Sensitivity Analysis

The machine tool bed is an important component of the center. The function is components of support column, worktable and so on. The machining accuracy can be influenced by the function machine tool bed. To establish the finite element model of horizontal machining center by Solid works. And the first six orders modal can be analyzed by Ansys. The dynamic sensitivity analysis is used to determine the parameters of stiffened plate by sensitivity optimization method. The better structure parameters can be getting by making a structural optimization design for the analysis. Finally, the dynamic characteristics and function of the machine tool bed can be improved.

Modal Analysis and Structure Optimization of a Printed Circuit Board NC Drilling Machine

The solid modeling of one type of printed circuit board NC drilling machine is built by Pro/Engineer, and ANSYS is applied for modal analysis. In this paper, the key influential factors of the structure of the drilling machine are found out, the structure is improved and two prioritization schemes are proposed. After analyzing the primary structure and the two optimized structures of the machine tool bed and then comparing the analysis results, the optimal scheme is proposed. The results show that the optimization improves the dynamic property and the machining precision of the drilling machine.

Process Design of Composite Concrete for CNC Machine Tool Bed

Composite concrete consists of silicate reinforced cement concrete inner core and polymer concrete external coating layer, has broad application prospects in the filed of machine tool large component producing. Process design of composite concrete has been done on the basis of tests, a small scale composite concrete machine tool bed model has been built for test, the related simulation and test has been done. The results show that the process of composite concrete is reasonable.

Guideway Joint Surface Properties of Heavy Machine Tools Based on the Theory of Similarity

In the process of Heavy NC machine tool design, the combination of static, dynamic characteristics directly determines and influences stiffness, damping, machining precision and work efficiency, Therefore the research on the combination of the characteristics become extremely important to the success of machine tool design. This study mainly studies the dynamic and static characteristic parameters of heavy machine tool guide way joint. And put forward a practical machine tool combining surface analysis method according to the experimental verification. How to obtain the analysis and test of the dynamic parameters to the combination is introduced. It is presented that small linear guide as a scale model based on similarity theory. And make a research on the static and dynamic characteristics of small guide joint and the conclusion extended to heavy machine set of faces. And the conclusion is extended to the heavy machine set of faces. It is introduced the spring damping unit of combined surface characteristics simulation during a small test about guide way dynamic performance analysis. Thus it can more effective simulate influence of combination of surface characteristics to components of the overall structure. The study analyze the dynamic performance of machine tool bed rail section by the verification and treat extraction of the first five modes as the analysis and forecast of the models of guide-way joint dynamic performance. The results can be used as reference data about structure and design of the machine tool due to the similarity principle and error range.

Damping research of fiber-reinforced resin mineral composite-based micromechanical modeling

Compared with cast iron and welded steel, fiber-reinforced resin mineral composite has better damping property that it can be used to produce precision machine tool beds in order to better satisfy the requirement of vibration alleviating. Suppose that the distribution of fibers in fiber-reinforced resin mineral composite is homogeneous, the damping model of single fiber is built on the basis of energy dissipation theory and the direction efficiency coefficient is defined as a new parameter to indicate the influence of single fiber’s orientation to the damping property of fiber-reinforced resin mineral composite. Typical fiber-reinforced resin mineral composite samples with different component ratio and surface treatment of fibers are prepared and their damping ratio is measured to validate the aforementioned assumptions. Research results show that the damping performance is better with longer fiber and lower interfacial bonding strength.

Effect of the gray cast iron microstructure on milling tool life and cutting force

Gray cast irons are frequently used in machine tool beds due to low cost, high vibration damping capacity, and easiness of manufacturing. The guiding standards for production of these alloys determine their classes based on the range of tensile strength and shape of graphites. This research project aims at investigating the differences in machinability between two gray cast irons belonging to the same class (GG25), i.e., within the same standard tolerance, but with different pearlitic/ferritic concentrations. Machinability was evaluated in terms of tool life and cutting forces in milling operations using carbide and ceramic tools and two different cutting speeds. Two different materials were used as samples, one containing 100 % pearlite and another with 50 % pearlite + 50 % ferrite. The results showed that milling of the 100 % pearlitic alloy led to faster tool wear and higher cutting forces than in the 50 % ferritic alloy. Ceramic tools exhibited longer life than carbide tools. The observed wear mechanisms were diffusion, attrition, and thermal cracks. However, material microstructure was observed to be far more significant for tool life and cutting force than the other input variables (cutting speed and tool material).

Stiffness model of machine tool supports using contact stiffness

The stiffness of machine tool supports should be properly designed for reducing both the ground disturbance vibration and the drive disturbance vibration. However, the stiffness cannot be easily calculated from the geometry and material properties of the support. In this paper, a 3D stiffness model of a machine tool support is proposed using contact stiffness. The stiffness in each direction is assumed to be determined by the contact stiffness at the interfaces and the bulk stiffnesses of the supports and the floor. The contact stiffness model proposed by Shimizu et al. is expanded to determine the contact stiffness in the normal and tangential directions of an interface. In the proposed model, the contact stiffness is obtained by multiplying the unit contact stiffness by the real contact area. The contact stiffness of concrete is experimentally investigated to estimate the stiffness between machine tool supports and the floor, and it was observed to be the primary determinant of the stiffness of interfaces between metal and concrete. Moreover, the unit contact stiffness of concrete is discovered to be less than 1/10 of those of the metals that were used for the study. The natural frequency and vibration mode shape of a model machine tool bed are also experimentally measured and used to verify the proposed stiffness model. The comparison of the results obtained from the two procedures shows that the natural frequency and vibration mode shape of a machine tool bed can be predicted using the proposed stiffness model.

S133015 大型平面研削盤における形状誤差の発生要因の究明 : 研削中の工作物温度分布のシミュレーション解析([S133]先進砥粒加工技術)

In surface grinding, the thermal deformation of a ground workpiece results in shape error. To obtain the high accuracy of the ground workpiece, it is important to understand the temperature distribution of the workpiece during grinding. However the temperature distribution of a large workpiece is not understood enough. Therefor in this study, a simulation analysis of the large workpiece is developed. The workpiece of about 1.3 tons in weight which is used as a machine tool bed was prepared for this study. In the developed simulation analysis method, the time variation of temperature distribution is calculated with finite element method. The grinding heat that transfers into the workpiece is estimated by measuring the grinding power during grinding. To evaluate validity of the method, in-process measurements of the temperature distribution were carried out. The temperature distribution was measured with thermistors put into many places of the ground workpiece. The simulated results agree well with the in-process measured temperature distribution.

Dynamic Analysis and Structure Improvements on Machine Tool Bed

The modal analysis of machine tool bed was done by means of finite element method. Find out its characteristics of vibration modal. Then structure improvements on arrangement of tool bed reinforcing plates were done. After the structure improvements the natural frequencies of the tool bed were improved.