新型铁基多孔含油材料滑块型滑动导轨的研究

导轨部件通常是整个机床刚度链中的最薄弱环节之一,因此导轨的力学性能直接影响机床整机的动态性能。提出了一种基于铁基多孔含油材料结合面的滑块型滑动导轨,分析了多孔含油材料结合面的刚度和阻尼特性;设计了多孔含油材料滑块型滑动导轨的一种矩形截面导轨形式,并对其润滑与低速平稳性进行了分析和实验验证;分析了所设计滑动导轨的导向精度,提出了滑块型滑动导轨设计时滑块跨度的设计原则。同滚动导轨相比,结果表明:该类型导轨具有高刚度、大阻尼和自润滑的特点,适合应用在中、较重负荷精密机床。     

Machine Tool with Active Magnetic Guides

High speed and high dynamic machining strategies require specific solutions for the components. The limits for speed and accuracy mainly depend on the machine structure, the drives and the guides. In this paper the development of a new high speed machining centre with actively controlled linear magnetic guides will be presented. The stiffness and damping properties of this innovative component will be discussed. The machining centre is equipped with linear direct drives in all three axes and uses lightweight slides on a solid concrete base. The machine structure and first results will be presented and compared to conventional machine tools.     

Determination of the load on profiled roller guide rails used as ram guides for metal-forming machines

Properties of profiled roller guide rails are high load capacity, high rigidity against tractive and compressive forces, low friction and high accuracy of guidance. The bearing clearance equals zero in profiled roller guide rails due to the pre-stress between carriage, rollers and guideway. For these reasons profiled roller guide rails have been used as ram guides in metal-forming machines for several years. Unlike sliding ram guides, guides with profiled roller guide rails can transmit tractive and compressive forces. Thereby the ram with its guides contributes to the stiffness of the whole machine. The load capacity of profiled roller guide rails is limited to the lifetime of the rollers. The load on the profiled roller guide rails during the production process is the main input for the calculation of the lifetime and can by now only be estimated roughly. The measuring method presented in this paper enables the determination of these loads.     

影响铣削颤振稳定性的因素与规律分析

应用Altintas切削颤振理论实现了铣削颤振的预测,并对影响铣削稳定性的机床系统因素进行了分析。研究发现,稳定性叶瓣图会受到机床的主轴-刀具系统模态参数影响,尤其是模态刚度、阻尼比和固有频率。另外,通过系统动刚度相同的条件下不同的阻尼比和模态刚度组合对铣削稳定性的影响分析发现,模态刚度对系统稳定性的影响要大于阻尼比的影响程度。分别对影响铣削加工稳定性的刀具参数、工件材料特性以及切削参数等因素及其对铣削稳定性的影响规律进行了分析。结果显示:减小刀具齿数、刀具螺旋角和刀具悬伸量,并增大刀具直径对于改善切削颤振有益;具有较小切向切削力系数和径向切削力系数的材料更容易实现稳定切削;减小铣削宽度,并采用顺铣方式,系统的临界切深更大。     

Identification method for damping parameters of roller linear guides

A virtual prototype can save cost and time during the design phase of today??s machine tools. Beside the calculation of the static behavior the prediction of the dynamic behavior gets more and more important, but the calculation results are often not satisfactory. Basically this is caused by a lack of knowledge about damping properties of machine tool components and their modeling. Within a project of the German Research Foundation (DFG) the damping of roller linear guides is investigated. The measuring method used to identify the components?? damping utilizes a simulation model to separate the damping of the machine component from the damping of the test bench itself and is state of the art. This article illustrates an extended version of this measuring method which isolates the components?? damping more precisely. Furthermore a first set of results for three types of roller linear guides with different preload classes is presented.     

XY-table for desktop machine tools based on a new fluidic planar drive

This paper presents the design of a XY-table for desktop machine tools that makes use of a novel fluid dynamic drive principle combined with an active aerostatic planar guide for contactless motion in two directions. The presented approach reduces the installation space and the number of required components significantly when compared with electric linear motors or drives with a ball screw that are used in conventional desktop machine tools. When designing the XY-table the requirements of a micro milling process of small workpieces were considered. The arrangement of the system is presented and the drive principle is explained. Important design parameters are obtained by the support of computational fluid dynamics. Different fluid profiles for the drive are developed and compared. The results of the numerical investigations are used for the design of the XY-table whose performance is finally shown in a micro milling setup.     

Tuneable clamping table for chatter avoidance in thin-walled part milling

Regenerative chatter is one of the main productivity limiting factors for thin-walled part milling due to their inherently low stiffness and damping properties. This paper presents a new concept called tuneable clamping table (TCT) for thin-walled part machining, which permits controlling the table mode through a rotary spring and eddy current modules. This allows introducing damping to one critical mode of the thin-walled part without any direct contact in the machining area. Two novel frequency tuning strategies to increase the dynamic stiffness and milling stability for the TCT are presented. The concept of TCT is experimentally validated through milling tests, demonstrating a notorious stability increase compared to a regular clamping.     

磁流变液阻尼器用于铣削颤振控制的仿真分析

确立了磁流变液的工作模式和MRF减振器的力学模型,利用设计的磁流变减振器构建了磁流变液减振系统,研究了磁流变减振器在铣削颤振控制中的应用。理论分析表明:磁流变减振器的刚度及阻尼随外加磁场强度的增加而增大,主振系统的振幅随磁场强度的增加而减小。磁流变减振器的减振效果随着磁场强度的增加逐渐增大,但并不是场强越大效果越好,而是有一最佳值。只要场强选取适当,采用磁流变减振装置可以控制铣削颤振现象的产生。     

Damping models for machine tool components of linear axes

To simulate the dynamic behaviour of machine tools, the stiffness, damping and inertia parameters of the structure are needed. While masses and stiffness parameters of structural parts can be obtained with a static measurement, the determination of damping parameters requires a thorough methodology. In this paper the common methodology for the identification of local damping parameters of machine components was extended by an additional step to isolate the damping of the test object more precisely. Furthermore test benches as well as the identified damping models for components of an exemplary linear axis are presented.     

Modeling the machining stability of a vertical milling machine under the influence of the preloaded linear guide

The prediction of machining stability is of great importance for the design of a machine tool capable of high-precision and high-speed machining. The machining performance is determined by the frequency characteristics of the machine tool structure and the dynamics of the cutting process, and can be expressed in terms of a stability lobe diagram. The aim of this study is to develop a finite element model to evaluate the dynamic characteristics and machining stability of a vertical milling system. Rolling interfaces with a contact stiffness defined by Hertz theory were used to couple the linear components and the machine structures in the finite element model. Using the model, the vibration mode that had a dominant influence on the dynamic stiffness and the machining stability was determined. The results of the finite element simulations reveal that linear guides with different preloads greatly affect the dynamic behavior and milling stability of the vertical column spindle head system. These results were validated by performing vibration and machining tests. We conclude that the proposed model can be used to accurately evaluate the dynamic performance of machine tool systems designed with various configurations and with different linear rolling components.     

Dynamic analysis of a motor-integrated method for a higher milling stability

The productivity in High Speed Cutting is often limited by undesirable vibration effects in the main spindle (chatter). In many cases these limits are far below the technically possible cutting parameters provided by the machine technology. This paper presents a new approach to a motor-integrated milling spindle with an embedded electromagnetic actuator to actively reduce chatter vibrations and increase productivity. It is based on the non-contact application of highly-dynamic damping forces on the spindle shaft. That way the process stability can be increased significantly. By measurement and simulation-based analysis of spindle dynamics and transient and analytical approaches to process stability, the efficiency of the damping method is demonstrated in theory. Finally, a new, soft magnetic composite based motor-integrated electromagnetic actuator is introduced in this article.     

Shrink fit tool holder connection stiffness/damping modeling for frequency response prediction in milling

In this paper we present a finite element modeling approach to determine the stiffness and damping behavior between the tool and holder in thermal shrink fit connections. The continuous contact stiffness/damping profile between the holder and portion of the tool inside the holder is approximated by defining coordinates along the interface contact length and assigning position-dependent stiffness and equivalent viscous damping values between the tool and holder. These values are incorporated into the third generation receptance coupling substructure analysis (RCSA) method, which is used to predict the tool point frequency response for milling applications. Once the holder and inserted tool section are connected using the finite element analysis-based stiffness and damping values, this subassembly is then rigidly coupled to the (measured) spindle–holder base and (modeled) tool. Experimental validation is provided.     

数控镗铣加工中心自动换刀系统中的机-液机械手

介绍了V116B型数控镗铣加工中心自动换刀系统中的机—液机械手的结构与工作原理及其液压系统，该机械手具有结构紧凑、工作平稳、定位准确的优点。     

Effect of preload of linear guides on dynamic characteristics of a vertical column–spindle system

Realization on the dynamic characteristics of the column–spindle system is of importance for enhancing the structural performance of a vertical milling machine. Generally, the spindle head is fed under linear guide mechanism through a ball-screw driver. To assess the dynamic characteristics of a vertical column–spindle system under the influence of a linear guide, this study developed a finite element model integrated with the modeling of linear components with the implementation of contact stiffness at the rolling interface. Both the finite element simulations and the vibration tests reveal that the preload of a linear guide greatly affects the vibration behavior associated with a spindle head, and the dynamic stiffness of the spindle head could be enhanced by increasing the preload of the linear guide. Current results clearly indicate that the simulations agree well with the experimental measurements. This also confirms that the proposed model can be successfully applied to evaluate the dynamics characteristics of machine tool systems of various configurations.     

BW60HS卧式加工中心整机模态测试

数控机床整机模态测试是分析机床抗振性、稳定性以及机床结构动力学优化设计的基础,同时也是解决机床振动问题的重要手段之一.在简要介绍数控机床模态测试原理的基础上,对沈阳机床集团BW60HS卧式加工中心的模态及动刚度进行了测试.获得了机床整机的固有频率、模态振型、阻尼比、动刚度等参数.通过测试发现,该机床滑板和立柱沿x方向的振动是该机床的薄弱环节,导致x方向动刚度显著降低.在综合分析的基础上,提出在清板和立柱内增设加强筋的方式来提高的整机系统的动结构性能.文章中的研究可为同类机床结构性能优化分析与实验提供必要的参考.     

铣边缺陷对螺旋缝埋弧焊管质量的影响及应对措施

铣边工艺被广泛用于螺旋缝埋弧焊管生产,但控制不好会导致焊管出现焊偏、未焊透等缺陷。结合铣边机的结构及工作原理,分析了常见的铣边缺陷形成原因及其对钢管质量的影响,提出了防止铣边缺陷产生的措施。     

精密机床负压吸附导轨的研究

介绍了负压吸附导轨的工作原理,针对精密机床开式静压方式工作过程中存在的漂移和运动不稳定问题,提出采用负压发生器与小孔节流流量控制器相结合的新型负压吸附静压支承技术,建立了负压吸附导轨计算模型,并对气膜刚度进行了分析计算,保证了精密机床开式静压导轨所需的气膜厚度和刚度。并将该技术应用到机床导轨中,应用表明:提高了机床运动稳定性及工件的加工精度。     

电磁齿轮传动系统的优化设计与动态仿真

对电磁齿轮这种新型非接触式传动机构及其工作原理进行了概述,并建立电磁转矩的数学模型,通过有限元方法对电磁齿轮结构参数进行了优化设计,在此基础上对影响电磁齿轮电磁力的主要控制参数进行了优化研究,并对电磁齿轮传动系统进行了动态仿真分析。通过合理设计电磁齿轮的结构参数和控制参数,可有效提高电磁齿轮的电磁力,所得结果为电磁齿轮传动系统的进一步设计提供了理论依据和数据参考。     

X80钢油气管道的钻铣切管机设计

围绕X80高强度油气管道的切割问题,分析了这一领域的国内外技术现状,介绍了钻铣切管机的组成及工作原理,设计了液压驱动方案。通过现场试验,得出了用钻铣切管机切割高强度油气管道具有在线切管不夹刀、切管时间短、能切割X80高强度油气管道的结论。     

Composite Machine Tool Structures for High Speed Milling Machines

To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. However, the productivity of mold manufacturing has not increased significantly because CNC milling machines have massive slides, which do not allow rapid acceleration and deceleration during the frequent starts/stops encountered in machining molds and dies. This paper presents the use of composites for these slides to overcome this limitation. The vertical and horizontal slides of a large CNC machine were constructed by bonding high-modulus carbon-fiber epoxy composite sandwiches to welded steel structures using adhesives. These composite structures reduced the weight of the vertical and horizontal slides by 34% and 26%, respectively, and increased damping by 1.5 to 5.7 times without sacrificing the stiffness. Without much tuning, this machine had a positional accuracy of ± 5μm per 300 mm of the slide displacement.