Friction welding of polyamides

Results from different experiments on friction welding are used to characterize the behavior of polyamide over a wide range of welding conditions. Several types and grades of polyamide were joined using the vibration and spin welding processes. The quality of the welds was evaluated by short time tensile tests and microscopy. In addition to the geometry of the parts being joined, the process parameters and the material were found to affect the quality of the weld, so that associated with each application is a different set of optimum welding parameters.     

Spot Welding–Adhesive Joints: Modelling and Testing

Modelling and testing of hybrid joints obtained by combination of two simple techniques, i.e., by application of spot welding and adhesive, is reported. The joints were subjected to uniaxial tension. The experiments were performed for: 1) a pure joining of the parts by spot welding and 2) spot welding–adhesive joining of the structural elements. A new experimental method was elaborated with application of two digital image correlation (DIC) systems. The method allowed for online monitoring of the deformation process of the joined elements with complex shapes. Modelling of the hybrid joints response to mechanical loading was performed by ABAQUS code. Damage process in the adhesive layer was taken into account. The obtained results lead to the conclusion that the strengthening of joints by the application of adhesive significantly improves static strength and energy absorption. The visible degradation process of the adhesive layer which started prior to the maximum value of force carrying the hybrid joint was obtained.     

Thickness effects in the vibration welding of polycarbonate

In vibration welding of thermoplastics, frictional work done by vibrating two parts under pressure, along their common interface, is used to generate heat to effect a weld. Past work on welding characterized the effects of weld parameters such as the weld frequency, the weld pressure, and the weld time, on the welding process and weld strength, and showed that the most important parameter affecting weld strength Is the weld penetration—the decrease in the distance between the parts being welded that is caused by lateral outflow of material in the molten film. However, those weld studies were based on specimens of constant nominal thickness (6.35 mm, 0.25 in). This paper is concerned with the effects of specimen thickness on the weld process and weld strength.     

塑料超声波扫描焊接技术

超声波扫描焊接是连续、高速地超声波焊接在固定超声波焊头或旋转焊头与砧座下方传送的平直工件的方法。该方法适用于至少有一个平面便于焊头接触的硬质热塑性塑料工件。某些织物或薄膜也适用于这种方法。无论是大型的还是小型的热塑性塑料工件都可以超声波扫描焊接。本文简述了超声波扫描焊接原理、分类、接头设计、特点及应用。     

塑料焊接技术在汽车配件中的应用

概述了汽车用塑料件的焊接方法及其焊接原理、过程、特点、适应性、应用和最新进展等。     

Rapid Bonding of Ti3SiC2 and Ti3AlC2 by Pulsed Electrical Current Heating

Inspired by pressure resistance welding of metallic materials, herein we describe how two MAX phases—Ti₃SiC₂ and Ti₃AlC₂—were successfully joined by a rapid electric current heating method in a pulsed electric current sintering furnace. No welding agent was employed and the total processing time was less than 6 min. When the bulk temperature of the joint couple exceeded 1070°C, good joints, with shear strength above 50 MPa, were achieved in both homo‐ and heterojunction joints.     

聚碳酸酯血液回收罐的超声波焊接工艺研究

从超声波焊接工艺和塑料制品的具体结构入手,结合超声波塑料焊接在医疗领域里的应用特点,以一次性使用血液回收罐装置部件焊接为例,制定了超声渡塑料焊接的工艺,确定了超声波焊接设备的参数并对工装进行了改造,分析了在医疗行业里塑料制品的应用特点和发展趋势.     

Effects of variable viscosity on the steady melting of thermoplastics during spin welding

The steady melting of several amorphous and semicrystalline polymers during spin welding is analyzed by solving a simplified set of momentum and energy balance equations, assuming a shear-rate and temperature-dependent viscosity. A numerical model is developed for predicting the flow field and the temperature distribution in the molten film. It is shown that the steady melting rate of the thermoplastic solid is affected by the variable viscosity, by the pressure applied on the parts to be joined, and by a balance between the viscous heat generation in the melt and the convection of colder material into the molten film. The convection of heat in the outflow direction is shown to have a much smaller effect on the melting process.     

钛合金加工过程中的表面防护

本文结合生产中遇到实际问题,简要介绍钛合金零组件在机械加工、热处理、冲压与热成型、焊接、化学加工、装配试车、检验、运输和储存、封存包装等生产过程中的表面防护方法。本文还特别提示:氯化物镀银引起的银脆也是造成承力部件断裂的原因之一。钛合金也存在银脆,钛合金零件镀银的防护方法,对于在海洋环境下服役的机械类产品,是否可取值得商榷。     

SHS Joining of Aluminum Conductors in the Presence of Copper

Aluminum conductors joining is an important issue in electric transportation industry. In some conditions, electric arc welding or friction stir welding could not be used to join these conductors due to environmental conditions, lack of welding tools, etc. In these cases, SHS method can be used as an appropriate process. In this work, two aluminum conductors (with 9.3-mm diameter and 125-mm length) were joined by SHS method. The conductors were made of commercially pure aluminum (Al > 99%) and, to enhance the joint strength, different weight percentages of copper (0.73–2.4 wt %) were added to green blends. The joints were characterized by hardness testing, electrical resistance, and optical metallography. With increasing Cu percentage, the electrical conductivity of the joint was found to decrease while the strength and hardness, to increase. In the presence of copper, the grain size of the join material was found to decrease.     

06Cr19Ni1O与Q235B的焊接工艺

承接了某公司PVC装置上的5台气体密封罐制造.其中罐顶材料为06Cr19Ni10,罐体加强箍为Q235B,两者相焊.第一台气体密封罐在焊接时出现了裂纹.后来调整了焊接工艺,顺利完成了其余4台设备的焊接,质量完全符合要求.     

氯气处理系统的改进

自贡鸿鹤化工股份有限公司离子膜烧碱工程氯氢处理过程中。氯气洗涤单元氯水低位密封槽多次出现简体与封头连接处塑料焊接损坏的情况。经过理论计算。将氯气洗涤塔和低位密封槽相连接的溢流管高度由1600mm改为800mm，避免了塑料焊接的损坏。且保证氯水循环泵不会出现掉液。     

Interdiffusion analysis based on novel ultrasonic welding method with inserting interposed sheet

The molecular movement process has been developed according to previous study on the novel ultrasonic welding method of inserting interposed sheet and its apparatus. Based on the classical reptation theory, a hauling theory of interdiffusion has been proposed which can accelerate molecular movement and interpenetration surprisingly. Hauling effect can promote the interdiffusion but has no effect on the interpenetration length. We involve a coefficient k_u to modify the relationship between the reptation time before and diffusion time, which can be related to the relative displacement and friction coefficient among the molecular in terms of the equations. The surface roughness, welding time, and welding force have been experimented and resulted uniformly in which the diffusion has been accelerated from our experiments. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

热板焊接的参数优化及质量控制

因为塑料材料种类繁多,不同的添加剂、零件形状、接头结构类型,以及其他诸多因素的相互作用,使得单因素优化设置工艺参数仅能满足焊接一般零件的需要。以这些参数为基础,借助数理统计的全因子实验设置优化的工艺参数,可以保证批量焊接产品的质量。研究表明,热板温度是影响接头强度的主要因素,加热时间次之,焊接压力影响最小。     

An approach to model the melt displacement and temperature profiles during the laser through‐transmission welding of thermoplastics

Laser transmission welding of thermoplastics is gaining importance in industrial series production because of its advantageous properties and the increasing interest in this technology. At the same time, the demand on ongoing investigations and research to understand the processes involved is being developed intensively. In this report, a simplified mathematic–physical model of laser transmission welding based on finite‐elements method will be presented. For the first calculations, the material PA6 and the quasi‐simultaneous laser welding process mode were chosen. The model comprises of the complete laser welding process, including the heating and the cooling phase. Boundary conditions and relevant process parameters were specified for the simulation, such as the laser beam intensity, the joining pressure, and the welding time. Flow and temperature profiles were then calculated. Because of the array of available boundary conditions, it is possible to continuously improve the model while comparing the simulated data with that obtained in the experiments. The experimental data were gathered by detecting the displacement of tracer particles in dependence on time and place. Moreover, the melt layer thickness was measured. In general, very good agreement was achieved between the calculated and the measured results. Once the steady–state conditions were achieved, no change in the remaining melt layer thickness, temperature, flow velocity, or weld strength was observed. It was seen that the maximum temperature was placed in the upper layers of the absorbent partner and not in the joining surface. Accordingly, the flow behavior is first detected in the absorbent partner, and afterwards in the transparent one. POLYM. ENG. SCI. 46:1565–1575, 2006. © 2006 Society of Plastics Engineers     

Thermoplastic vibration welding: Review of process phenomenology and processing–structure–property interrelationships

Vibration welding offers a robust method for physically joining thermoplastics to fabricate complex hollow assemblies from simpler injection‐molded articles without using an external heat source, adhesives, or mechanical fasteners. Vibration welding involves a complex interplay of several phenomena—solid (Coulomb) friction, melting, high strain‐rate, pressure‐driven, strong (high‐strain) melt flows, solidification, and microstructure development—which ultimately govern the strength and integrity of the weld. Defects in the weld region may lead to catastrophic failure of the welded assembly. In this article, the current understanding of the processing–structure–property relationships in the context of vibration welding of thermoplastics and polymer‐matrix composites is reviewed. Experimental as well as analytical methods of investigation of the vibration welding process phenomenology are presented. The interrelationships between the microstructure in the weld region and the resulting weld strength and fatigue behavior are then discussed in the light of this phenomenological information for neat polymers, filled polymers, polymer blends, and foams. This review is also aimed at identifying the areas requiring further investigation with regard to understanding vibration welding phenomenology and weld structure–property relationships. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

MIG焊接V型熔池特性的数理模型建立

通过对MIG坡口焊接工艺过程的分析将三维焊接物理过程简化为二维数理模型,建立移动高斯热源模型用于描述电弧与工件的热作用,建立熔池内的CFD模型用以描述熔池内熔化／凝固过程的流动传热传质现象,对典型V型坡口焊接过程进行实验和数值模拟研究,通过与实验得到的工件截面金相图对比分析验证了数理模型的准确性,最后对数理模型中高斯热源参数及熔池流动的驱动力机理模型进行了进一步讨论。结果表明通过合理的模型参数选择二维数理模型可以准确地分析MIG坡口焊过程熔池的演变过程。     

Lumped circuit approximations for flux in systems governed by the laplace equation: The stoma of zero thickness

It is pointed out that the mass transfer coefficients for two complicated geometries (well source in a plane; disc source over a plane) are well approximated by their standard lumped circuit approximations, although in the disc case this seems not to have been recognized. The lumped circuit method is then shown to work equally well for a tube containing a punctured diaphragm and for a plane with a circular aperture, one side of the plane being nonabsorbing and the other a source. The latter (and previously unsolved) problem, which is that of the thin stoma, is handled by formulating it in terms of coupled dual integral equations which are then treated by Neumann expansion techniques; explicit analytic and numerical details are provided in the hope that this little known—but powerful—method of solution will gain wider currency.     

Development of an automated wood welding process

Friction welding of wood is an active field of research and would seem to be a potential joining technology in wood industries in the near future. Despite numerous scientific publications in this field, automated industrial applications of this technique are not common up to now. In this paper, we developed an automated welding process that can be easily implemented in industry. The use of beech wood samples is motivated because (i) this species is abundant in the forest resource, (ii) the anatomical structure is homogeneous and therefore highly suitable for the welding process and (iii) the average wood density is high. For the welding process, a sequential control was developed and four different welding modes were applied. We tested four welding modes with a constant rotation speed of the drilling machine (1800?t.mn). During the dowel insertion, the linear displacement was tested for two different constant speeds and for two varying speeds. The results of the pull-out strength test show that the forces during the welding process as well as the strength of the joints produced differ depending on the welding mode. Based on the results it can be recommended that a two-step welding process is applied for wood welding. With the two steps, the forces at the welding machine are kept low and the quality of the joint is high. The sequential control developed can be applied and adapted for different industrial applications. These findings should convince industrial decision-makers of the applicability of this process for daily production.     

A step towards understanding the heating phase of laser transmission welding in polymers

In recent years, laser transmission welding has gained in significance by displaying its specific advantages among the established welding processes for thermoplastics. However, a deep understanding of the developed process variants is so far missing. Useful results for temperature development were obtained in cases of high absorption constants by setting up an analytical model by analogy to single‐sided heat impulse welding. Yet there is no physico‐mathematical model considering the different energy conditions for joining parts with various absorption properties. This investigation is a first step towards a deep and detailed insight into the heating phase of the laser transmission welding process. Experimental data for temperature progression was collected for polypropylene. In addition, an analysis of the heat transfer problem using the finite element method showed a good level of agreement with the experimental results.