Simplified and efficient calibration of a mechanistic cutting force model for ball-end milling

Accurate evaluation of the empirical coefficients of a mechanistic cutting force model is critical to the reliability of the predicted cutting forces. This paper presents a simplified and efficient method to determine the cutting force coefficients of a ball-end milling model. The unique feature of this new method is that only a single half-slot cut is to be performed to calibrate the empirical force coefficients that are valid over a wide range of cutting conditions. The instantaneous cutting forces are used with the established helical cutting edge profile on the ball-end mill. The half-slot calibration cut enables successive determination of the lumped discrete values of the varying cutting mechanics parameters along the cutter axis whereas the size effect parameters are determined from the known variation of undeformed chip thickness with cutter rotation. The effectiveness of the present method in determining the cutting force coefficients has been demonstrated experimentally with a series of verification test cuts.     

搅拌工具尺寸和工艺参数对塑料搅拌摩擦焊焊缝质量的影响

用不同尺寸的搅拌工具对聚氯乙烯(PVC)板材进行了搅拌摩擦对接焊工艺试验.试验证明,在搅拌工具肩部直径为30 mm,搅拌头直径为10 mm,搅拌头旋转速度为1 660 r/min,焊接速度为25 mm/min的情况下,可以得到焊缝饱满、成形美观的焊接接头.提高搅拌头的旋转速度可以成比例地提高焊接温度;焊接速度的影响较复杂,增大焊接速度一方面会降低焊接热输入,一方面又会间接地增大搅拌头的进给阻力,从而增大摩擦发热功率,提高焊接温度;搅拌工具肩部直径直接影响肩部与被焊材料表面的摩擦发热功率,增大肩部直径可以提高焊接温度,还有利于阻止焊缝材料的飞溅和外溢;而搅拌头直径的影响较复杂,增大它既可以提高搅拌头侧面与被焊材料之间的相对运动线速度,从而提高焊接温度,又会增加被焊材料的吸热功率和传热面积,从而降低焊接温度.     

An Experimental Study on Laser Cutting Mechanisms of Polycrystalline Diamond Compacts

The objective of this study is to experimentally investigate the cutting mechanisms of polycrystalline diamond compacts (PDC) using two different lasers: (a) a near infrared Nd:YAG laser (Neodymium-doped Yttrium Aluminum Garnet) of 1064 nm wavelength and 100 μs pulse width; and (b) a green light KTP (Potassium Titanyl Phosphate)/Nd:YAG laser of 532 nm wavelength and 120 ns pulse width. To realize the objective, the study applies polishing, lapping and etching processes to the cut-surfaces of the PDC samples. It further observes and analyzes the processed cut-surfaces with scanning electron microscopy (SEM) and Raman spectroscopy. A discussion is provided to reveal the underlying physics of the laser cutting mechanisms, and a conclusion is drawn based on the outcomes from the experimental investigation and the discussion.     

机械零件刚度的模糊可靠性设计

介绍了机械零件刚度模糊可靠性设计变形分布参数和刚度隶属函数的确定,导出了零件刚度模糊可靠度的计算公式,并通过机床主轴模糊可靠性设计实例说明机械零件模糊可靠性的计算方法.     

Wear and cutting performance of diamond composite material-a comparison with tungsten carbide

A series of wear and rock cutting tests were undertaken to assess the wear and cutting performance of a thermally stable diamond composite (TSDC). The wear tests were conducted on a newly designed wear testing rig in which a rotating aluminium oxide grinding wheel is turned (also known as machined) by the testing tool element.The rock cutting tests were performed on a linear rock-cutting planer. The thrust and cutting forces acting on the tool were measured during these tests. A tungsten carbide element was also studied for comparative purposes. The wear coefficients of both materials were used to evaluate wear performance while cutting performance was assessed by tool wear and the rates of increase in forces with cutting distance.     

叠加阀在组合机床液压系统中的应用

文章简要介绍了新型液压元件--叠加阀,并列举实例说明了在组合机床中采用叠加阀的液压系统设计.     

机床铸件导轨镶铸冷却水管的工艺技术

机床铸件导轨镶铸冷却水管是一项新技术,介绍该技术的试验开发过程、铸造工艺参数的设计、生产过程的铸造工艺规范,本试验开发项目的成功将促进镶铸技术在机床铸件上的应用.     

Investigating the correlation between nano-impact fracture resistance and hardness/modulus ratio from nanoindentation at 25-500 °C and the fracture resistance and lifetime of cutting tools with Ti1−xAlxN (x = 0.5 and 0.67) PVD coatings in milling operations

A novel laboratory technique, nano-impact testing, has been used to test Ti_1−xAl_xN (x = 0.5 and 0.67) PVD coated WC-Co inserts at 25-500 °C. Cutting tool life was studied under conditions of face milling of the structural AISI 1040 steel; the end milling of hardened 4340 steel (HRC 40) and TiAl6V4 alloy. A correlation was found between the results of the rapid nano-impact test and milling tests. When x = 0.67 improved resistance to fracture was found during milling operations and also in the nano-impact test of this coating compared to when x = 0.50. The coating protects the cutting tool surface against the chipping that is typical for cutting operations with intensive adhesive interaction with workpiece materials such as machining of Ti-based alloys. The results give encouragement that the elevated temperature nano-impact test can be used to predict the wear and fracture resistance of hard coatings during milling operations. At 500 °C nanoindentation shows there is a lower H/E_r ratio for the PVD coatings compared to room temperature, consistent with reduced fracture observed at this temperature in the nano-impact test.     

数控机床主轴无报警故障的检修

以XK71SF数控铣床、XHK716加工中心及进口加工中心为例，介绍了数控机床主轴无报警故障的几种检修方法。     

数控机床位置伺服在线调试与动态性能分析研究

介绍一种在数控机床位置伺服系统在线调试中应用系统动态性能分析方法的基本原理，给出了一种位置伺服系统动态响应曲线、动态性能分析及其主要技术指标的实例。