采用洪水冷却技术的蜗轮磨床热结构优化设计及温度控制外文翻译-中英11700字
外文翻译
学 院
专 业
届 别
学 号
姓 名
指导教师
200 Ｘ 年 Ｘ 月 Ｘ日
2420
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For the worm gear grinding machine using flood cooling technology, the coolant absorbs the grinding heat in the
machining process and flows on the machine bed, which directly affects the relative position between tool and
workpiece. The existing thermal structure analysis and the temperature control research lack in-depth research on
thermal problems related with the coolant flowing along the machine bed. In order to reduce the thermal deformation
of the machine bed, this paper proposes a novel structure with double-layer coolant channel to improve the thermal
characteristics of the machine bed, and the cooling fluid is controlled to maintain an even temperature distribution of
machine bed through this structure. In addition, based on a comprehensive analysis of the machine bed heat sources
and boundary conditions, a more accurate coolant convection heat transfer coefficient distribution was obtained by
using CFX software, and a flow-thermal-structural multi-field sequential coupling finite element thermal
characteristic analysis model was established to study the thermal characteristics of the machine bed. The results
show that the maximum prediction error of the model is less than 6.77% compared with the experimental data under
the same working conditions. The temperature distribution of the proposed machine bed structure is more uniform
than that of the original one. The maximum temperature difference is reduced by 1.7 °C, which shows that this
method can effectively reduce the relative deflection between the workpiece column and the column. The proposed
machine bed structure decreases the thermal deformation>s sensitivity to the temperature of the coolant and has a
high adaptability to external temperature fluctuations.
?"#% Machinebed .Thermalstructuredesign .Coolant .Flow-thermal-
structuralcouplingsimulation .Wormgeargrinding
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1 Introduction
Thermal influence on machine tools is one of the largest
errors onmachined workpieces. The existing results
haveshown that up to 75% of machining errors are
caused by the thermal problems of machine tools [1].
Therefore, in order to improve the machining accuracy
of CNC machine tools, how to reduce the thermal
deformation caused by the uneven temperature
distribution of machine tools has become an urgent issue
to be solved.
Extensive researches have been conducted on the
thermal characteristics of machine tools. The thermal
deformation of the machine tool is a comprehensive
result
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under the influence of internal and external heat sources.
Heat sources transfer heat to the machine tool under
certain working conditions, which causes the
temperature rise of each part of the machine tool and the
temperature gradient. Then various thermal
displacements such as bending, pulling, and twisting are
caused due to the different shape and structure of each
part, and finally the points, lines, and surfaces related to
the machining accuracy have relative displacement. The
heat generation varies with the change of processing
content and time. In addition, the machine tool itself is
with a certain heat capacity, and its temperature rise will
appear at a certain time lag phenomenon. Therefore, the
thermal deformation of machine tool is a non-linear
time-varying function with the change of temperature.
Bryan [2] and Ramesh [3] pointed out there are seven
kinds of heat sources for grinding machine and
described the action form of each heat source to the
thermal error. With the development of computer
technology, the thermal characteristics of machine tools
have been studied by using finite element method, finite
difference method, or finite difference element method.
The accuracy of thermal characteristic analysis of
machine tool depends on the accuracy of the established
analysis model. An accurate and complete thermal
characteristic analysis model should fully consider all
kinds of heat sources and heat transfer of machine tool
under the actual working conditions. Maier T. et al. [4]
established a thermal structure coupling analysis model
considering the influence of the cutting process on the
whole machine, and studied the relationship between the
processing process, the heat source, and the machine
structure. Zhang J.F. [5] established a thermal
characteristic analysis model for the vertical machining
center based on the analysis of the main internal and
external heat sources and the contact thermal resistance
of whole machine, and he verified the validity of the
model by comparing the simulation results with
experimental data under different working conditions.
The flood cooling technology is generally adopted in the
grinding process of gear grinding machine. The coolant
absorbing the grinding heat distributes in the whole flow
channel of the machine bed, which has significant
influence on the thermal characteristics of the whole
machine. Josef et al. [6] compared the thermal
characteristics of the machine tool with and without
cutting fluid by experiment. The influence of the coolant
being considered as an important heat source on the
thermal characteristics of the whole machine is analyzed
[7, 8].
Thermal structure design optimization and
temperature control based on the analysis results of
thermal characteristics are two main methods to reduce
thermal error in the machine tools design stage. The
structure of the key components is optimized or
redesigned without changing the heating power of the
thermal source of the machine tool, which contributes to
a more uniform temperature distribution inside the
machine tool. The basic design theory is the Hthermal
plane of symmetry.I And the finite-element method is
one of the main approaches for complex structure
machine tool thermal performance analysis and
structural optimization research [9]. Zhang F. [10]
reconstructed the thermal structure of a machine tool
headstock and effectively reduced the thermal
deformation of the machining center in the vertical
direction. Mayr J. et al. [11] proposed a new welded
machine tool frame design characterized by two
columns to get a symmetric construction. Jedrzjewski J.
[12] presented a concept of optimizing thermal
properties of machine tools based on the separate
optimization of drive systems and supporting structure.
Another effective method to reduce thermally induced
errors is to remove as much of the internally generated
heat as possible by convection heat transfer utilizing
cooling fluids. Cooling strategies have been used to
reduce temperature gradients in machine tool structures.
Jiang S. [13] carried out a thermal design work for the
vertical machining center headstock by introducing a
dual cooling system, utilizing a forced water cooling
subsystem and a forced air cooling one. Yoshioka H. et
al. [14] studied the control of supply air temperature to
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作者：闻远设计
分类：课程设计课件资料
价格：15光币
属性：32 页
大小：16.08MB
格式：DOC
时间：2022-12-25
