Search

Arc welding has always presented a challenge to robot operation. Variations in joint fit-up, positional welding requirements and the high levels of welder skill demanded by transient changes in operating conditions are just some of the variables with which any arc welding robot must cope. The article examines how an inertia-less high-frequency weaving technique using a novel deflector system can solve many of these problems even for high speed seam tracking. [ABSTRACT FROM AUTHOR]

Cleaning castings is a common process in manufacturing and there have been various kinds of robotic applications in deburring, polishing, etc. However, robots have not been applied to surface machining because of difficulties in metal removal control. Robotic Vision Systems Inc. is currently engaged in a research effort to develop a robotic disc or wheel grinding unit for surface machining applications. Novel design features, such as passive compliance and visual feedback, will provide system performance that offers more consistent quality and lower production costs than manual methods. [ABSTRACT FROM AUTHOR]

In recent years the worldwide development and use of automated systems within the manufacturing industry has led to a proliferation of system designs, mainly involving the integration of a wide range of suitable computerised machine tools and material handling equipment. This customisation of system design has given rise to some disquiet in respect of the limitations of such systems, and their realised as opposed to theoretical capabilities. Accordingly this paper presents an assessment of the current characteristics of Flexible Manufacturing Systems based on a series of field visits and an extensive literature survey. [ABSTRACT FROM AUTHOR]

In this paper an integer programming approach to the process planning problem is presented. Although the presented approach can be applied to any type of manufacturing system, some implications of the flexible manufacturing environment on process planning models are discussed. The relationship between the process planning models and the FMS software environment is shown. Algorithms for solving the developed models as well as computational results are discussed. [ABSTRACT FROM AUTHOR]

The authors have worked out a mathematical model of non-synchronous assembly lines (NSAL). This model is based on some probabilistic relationships between manual and automatic assembly operations and logical relations characterised by the interaction which occurs when there is a limited storage of work carriers between assembly positions. Statistic modelling of more than 1500 examples of NSAL with various structures have been performed using this model. Generalised data made it possible to develop a graphic analytical calculation method for determining productivity and availability factors for the lines taking into account the number of the line positions and also their productivity and reliability factors. [ABSTRACT FROM AUTHOR]

The majority of workpieces found in industry have cylindrical shapes. The design of jaws to enable the concentric handling of these workpieces by grippers with quasi-parallel jaw-closure is investigated. The jaws are given specially-shaped profiles resembling the Greek letter v. The basic equations defining such profiles are given along with an analysis of the geometrical parameters which govern the jaw dimensions. The rules for selecting the parameters to achieve compact jaw designs are enshrined in a computer program which implements these rules. By this means, optimal jaw profiles from specifications of workpiece and gripper dimensions can be determined. Sample computer outputs illustrate the effectiveness of the method. [ABSTRACT FROM AUTHOR]

This paper examines the benefits to production efficiency which can accrue by investing in computer systems, and provides an insight into the trade-offbetween computer links and computer integration. [ABSTRACT FROM AUTHOR]

Utilising traditional machinery, sheet metal parts are usually produced in large series. Decreasing lot sizes and quickly changing demand calls for highly flexible production systems. In spite of their rather high system cost, high power laser production systems could prove profitable on account of their big advantages in terms of flexibility. A unique flexible manufacturing system, which is provided by laser, was planned for a broad spectrum of three-dimensional sheet metal parts. In this system, medium-sized series are to be produced in three shifts, with the third shift being unattended. For the implementation of the combination of laser cutting and laser welding, a feasibility study has been performed that includes system and operational cost comparisons. [ABSTRACT FROM AUTHOR]

This paper explores some of the critical issues in the development of factory automation systems. Amongst the most significant of these can be considered the role of people, the generation of controls software, the reconfiguration of the manufacturing hardware and software to allow an increased variety of tasks to be carried out and automatic error recovery. This paper reports the design and operation of a cell exploring potential solutions to some of the problems arising from these issues and presents further thoughts on their solution. [ABSTRACT FROM AUTHOR]

This paper outlines the development of a computer vision system to enhance classification criteria for the inspection of infrared light emitting diodes (LEDs). Infrared LEDs used for fibre optics and optical switches are presently classified solely on the basis of power output. This test is performed by focusing the light beam from the LED through a circular aperture onto a solar cell. The output current from the solar cell is translated into a power output reading for the LED. The approach is limited in that it provides no information about other characteristics such as the misalignment of the beam from the mechanical centre or the intensity distribution of the beam. Improved classification criteria and testing methods based on emitted light intensity distribution can be utilised in engineering revision, setting specifications, monitoring manufacturing problems and classification for different applications. [ABSTRACT FROM AUTHOR]

This paper deals with an automated assembly line using Seiko high precision robots (D-TRAN XY-3000) and incorporating a Seiko Vision-I system exclusively developed for the assembly of wrist watch casings. The line has the capability of instant changeover to cater for various types of watch casing. It discusses the reasons for the development of this extremely flexible assembly line, which is now in operation at the Takatsuka plant of Seiko Instrument & Electronics Ltd. The assembly of wrist watch casings is achieved by analysing the features of casing assembly so as to integrate the vision system and robots into the line. [ABSTRACT FROM AUTHOR]

Two heuristic algorithms are presented for solving the scheduling problem in a statically loaded Flexible Manufacturing System (FMS). The heuristics goal is to minimise the total cost resulting from the tardiness of jobs. Using the same heuristics, an iterative method is proposed to find an optimal makespan and the average lead time. Modifications required to handle the case of a dynamically loaded FMS are then presented. Simulation results show that the developed heuristics appear to out perform the other published techniques used in obtaining the schedules associated with minimum makespan, minimum average lead time and minimum cost of tardiness. Finally, the simulation of the dynamic case shows that the algorithms could be implemented locally on each station for the scheduling calculation. [ABSTRACT FROM AUTHOR]

The widespread use of simulation as an analysis and a design tool has led to the development of a large number of programming languages (more than 600 by the end of 1980). In fact, in corporate planning many analysts opt for simulation in dealing with complex types of problems where analytic methods offer limited scope. In manufacturing the use of simulation has been much less, mainly as a result of a vacuum in model building expertise. Nevertheless, general and special purpose simulations have now been employed increasingly to aid the design and implementation of new manufacturing cells as well as to establish schedules, control inventory, balance production and determine loading capacities. This paper explores the simulation methodology and its applications in a manufacturing environment and highlights its advantages by solving an industrial problem. [ABSTRACT FROM AUTHOR]

Transducers with in-built microprocessors will gain in popularity over the next few years. As they do so, they will become a familiar component in the large and complex control systems in process and manufacturing environments. This paper discusses the use of Local Area Networks' (LANs), digital communication techniques in a system that can provide an efficient and flexible interconnect for a number of transducers involved in monitoring and control. Justification of the use of a bus type system, as opposed to other LAN topologies, is based on it providing a minimal interconnect distance and greatest interconnect flexibility. Simulations have been performed to determine the loading/delay characteristics of two types of bus protocol when implemented on single chip microprocessors. These delays are then used in the simulation of a control loop to determine their effect on the output error of a simple first order process. The investigation of these responses will eventually lead to system design criteria for loading/control response objectives. [ABSTRACT FROM AUTHOR]

The policy of Land Rover Limited towards new technology in manufacturing has always been one of forward thinking, but based on a 'step-by-step' approach to ensure successful implementation. This is the approach being taken with CADCAM in general. A development programme has been established to ensure that as the quantity of CAD equipment increased in manufacturing, the systems are at a level where significant benefits are achievable. Land Rover Limited has undertaken a major rationalisation project which involved relocating 15 external sites onto one main location. A large amount of plant layout work was necessary to carry out the project and this paper describes the development work on CADCAM in order to achieve a working system in time for implementing the project with the assistance of a CAD system and the subsequent use of the system by the facilities engineers. [ABSTRACT FROM AUTHOR]

Problems connected with the insertion of rubber seals in the internal grooves of hydraulic cylinders are presented, and functional specifications defined for a device oriented to automate insertion operations by the use of an industrial robot. A prototype is described, which consists of a special purpose end effector with three fingers, two of which can be moved in plane trajectories by stepper motors, so that they can grip and bend the seal to a particular shape and finally insert it, following clearly defined strategies. Test activity using a currently available industrial robot is described and future developments outlined. [ABSTRACT FROM AUTHOR]

This paper discusses a number of possible strategies for specifying the geometric characteristics of a part to be manufactured using traditional metal removal processes. This specification is used in a knowledge based process planning system. The schemes discussed here are suitable for characterising a part to be manufactured in qualitative and quantitative terms so that a number of rules for process planning may be formulated in a fairly straightforward way. The basic building blocks for part characterisation are a number of primitive 'shapes'. It is possible to use 'shape modifiers' and 'sections' to indicate the part more accurately. A number of methods have been discussed to specify interrelationships between the primitive shapes constituting the part to be manufactured. [ABSTRACT FROM AUTHOR]

This paper describes a prototype six degree of freedom 8kg capacity robot constructed to meet the needs of robotics research at Imperial College. With future robot requirements in mind, the robot control system was developed in collaboration with R.D. Projects Ltd. [ABSTRACT FROM AUTHOR]

This paper presents the design and method of development of a new three-pad BTA tool. The advantages of this cutting tool over a conventional two-pad BTA tool are brought out using a probabilistic approach in both the static and dynamic case. Experiments were conducted with the new three-pad tool, and it confirmed the theoretical prediction that the three-pad tool is more stable than the conventional BTA tool. Also, the cause of grooves observed on the workpiece produced by the two-pad tool has been explained. Further, it is observed that the third pad stiffens the tool thereby improving the chip breaking effect which improves the quality of the holes produced at high feeds. Thus this new development increases the productivity and improves workpiece accuracy in deep hole machining. [ABSTRACT FROM AUTHOR]

The concept of using state tables to define real time control alternatives for an automated manufacturing system has been previously documented; however, the methodology for obtaining values for the control vectors associated with these tables has not been well defined. The procedure presented in this paper utilises several data analysis tools to create, modify, cluster, merge, and recognise control data which is appropriate to a specific control situation. Experiments with a computer-controlled, manufacturing cell, which emphasises material handling, will be utilised throughout to explain the methodology. Experimental results are discussed. [ABSTRACT FROM AUTHOR]

Introduction of flexible machining systems incorporating robotic manipulators for high speed transfer of tools and workpieces entails high capital investment. This is an important constraint which limits the scope for experimentation and emphasises the importance of reliability as a deciding factor in the use of such systems. This paper describes a typical flexible machining cell configuration. Operational details relating to its elements and their components are included. A large amount of data concerning the failure characteristics of various subsystem elements are gathered and processed. Using a representative sample, qualitative and quantitative analyses of the system reliability are carried out using various reliability evaluation techniques. These include block diagram analysis (BDA), fault tree analysis (FTA) and a discrete Markov model. In particular attention is paid to the availability of the robot-assisted tool delivery system, including sensing, measuring and signal conditioning devices. [ABSTRACT FROM AUTHOR]

The successful economic exploitation of automatic assembly equipment is strongly dependent on the output of the machines and thus on a high level of availability. Hence to exploit the high investment, necessary for such equipment the availability must be at as high a level as possible. A survey of about 40 assembly lines with respect to weak points in the assembly equipment has revealed that there is a breakdown on average every 2.11 minutes. Consequently there is the need for operators to clear the faults in order to obtain a satisfactory availability. With existing machinery it is impossible to operate an automatic line without some manual supervision. Based on this experience the paper outlines strategies for planning, start-up and operating assembly lines to produce very high availability. These strategies are described in the paper and illustrated by examples from field experiences. [ABSTRACT FROM AUTHOR]

Flexible manufacturing systems (FMS) constitute a considerable capital investment which must be fully utilised by uninterrupted production. The analysis of reliability at planning and development stages in the implementation of FMS is essential, since it can change both the system design and the operating philosophy to give improvements in the overall system performance. The main objective of this paper is to propose a technique for assessing the reliability of flexible manufacturing systems and further to discuss the unsuitability of the traditional reliability techniques in the study of such systems. It is shown that simulation studies in thereliability of flexible manufacturing can be applied in the analysis of alternative approaches to system design. The key terms, 'Manufacturing Capability', 'Production Efficiency' and 'Demanded Production Lead Time Success Ratio' are introduced as measures which can assess a system's performance. A typical flexible manufacturing cell is then analysed for reliability using predicted reliability data. The effect of equipment redundancy, buffer stock size and production priority rules on the cells performance are finally discussed. [ABSTRACT FROM AUTHOR]

From a review of individual time standards, handbook data, the results of experiments and on-site industrial observations, a database of operation times for the assembly of electronic components is developed. The results are presented in a form useful in cost estimating procedures. [ABSTRACT FROM AUTHOR]

Oki Electric Industry Co Ltd has developed an automatic production line which achieves the company's target of total factory automation based on Oki's unmanned system concept. A summary of the automatic production line, developed technology, and its results are outlined in this paper. [ABSTRACT FROM AUTHOR]

The realising of the great benefits of odometrically-controlled, freeranging, automatically guided vehicles has been prevented by the lack of an adequate secondary 'absolute' vehicle location technique, required to overcome the cumulative errors inherent in odometry. In this paper the sources of odometric error are discussed, and the resulting positional uncertainties investigated. The dominant amongst these is identified as being the uncertainty in the lateral location of the vehicle, and this is quantified as a function of odometric error. A location technique addressed specifically at this uncertainty has been devised and constructed, employing linear arrays of light sensitive elements and a narrow light beam. This system and its associated electronics and software is described. [ABSTRACT FROM AUTHOR]

Many machine tool manufacturers, research institutes and universities are currently conducting studies aimed at achieving efficient unmanned machining on Computer Numerically Controlled (CNC) equipment. The objective is to provide the infrastructure necessary for the development of fully automated production systems. Accordingly, this paper seeks to outline the concepts involved in computerised machine tool monitoring and control, thereby illustrating the use of intelligent sensor based manufacturing management systems in unmanned production. [ABSTRACT FROM AUTHOR]

This paper considers the method of selection of optimal variant for designing assembly lines with the help of best solutions guided search. Optimisation is based on one and multi-criteria estimation and also conditions of uncertainty are taken into consideration. Practical optimisation results are discussed for diesel engine pumps assembly lines. [ABSTRACT FROM AUTHOR]

Artificial Intelligence (AI) has enormous relevance for Advanced Manufacturing Technology. The paper reviews the main AI techniques from an engineering viewpoint and explains how they differ from conventional computing methods. Several AI languages are discussed with reference to key features which should be considered for selection purposes. Limitations of present software products are outlined and the main benefits of AI for AMT are summarised. It is concluded that the importance of AI to manufacturing is considerable and the need for intelligent capability within a computational framework is likely to increase dramatically as AMT develops. [ABSTRACT FROM AUTHOR]

Group Technology is recognised as one of the best solutions to resolve the problems in a modern manufacturing system. A sound classification and coding system is the basis of successful implementations of GT concept. However, human interpretation of engineering drawings is required during the coding process. In order to eliminate this human interpretation, an algorithm for automatically extracting surface features of symmetrical rotational parts was developed. This algorithm is used as the front-end of an automated classification and coding system. The methodology is detailed and an implementation procedure for generating KK3 GT codes is described along with examples. [ABSTRACT FROM AUTHOR]

The thermal response behaviour of the metallic mould is of fundamental and paramount importance in controlling the rate of solidification of castings as well as their mechanical and technological properties. This problem is, therefore, addressed in the present paper in order to gain an insight into the mechanism of heat transfer through the mould wall and to provide the designer with some basic information. In order to reveal the nature of the time variation of the temperature field within the mould wall, the analysis is confined to the case of undimensional heat flow under transient condition. This has been accomplished by applying the finite element method in a dimensionless form. Conclusions regarding the individual and combined effects of various governing variables on the thermal process have been drawn. Depending on the combination of the principal variables, the results indicated that there are four fundamental patterns for the transient temperature field. Experimental data regarding the time variation of the temperature at the mould inner surface is presented in some analytical form. Using this data, the application of Duhamel's integral to predict the temperature field under transient boundary condition is demonstrated. [ABSTRACT FROM AUTHOR]

Proper process control procedures are important considerations in the optimisation of any manufacturing process. Ultimately, a continuous update on the size and quality of the products being manufactured is desirable. A non-contact laser detector system was developed to measure the dimensions of wood products in a real-time operating environment, employing a two-axis lateral effect photodiode as the sensor. Computer algorithms were developed to measure the thickness, warp, and width of wood samples (pencil slats). The effect of mechanical vibration due to slat transport was identified and when possible eliminated. The system was evaluated at different transport speeds. The results indicated that, except for width measurement which is limited by the computing speed, the system can measure thickness and warp quite accurately at feed speeds of 240 feet per minute. Although the work described is specific to certain applications, the implications for use in other industrial activities where visual sensing is required is apparent. [ABSTRACT FROM AUTHOR]

This paper presents a comparison of the performance characteristics of TiN (Titanium nitride) and ZrN (Zirconium nitride) coatings on split point drills. The objective of this work was to choose the better coating for machining tough materials like INCONEL. This leads to an increased productivity of drilling holes in certain components of environmental control systems and fuel control systems (in aerospace industry) made of tough materials like INCONEL. The comparison of the performance characteristics was based on the measurement of the mean values and dynamic fluctuations of the cutting force and the number of holes drilled under the same optimum machining conditions. The measurements were carried out using two specially designed piezoelectric dynamometers. The dynamometer was calibrated from static and dynamic outputs and techniques were employed for increasing the measuring accuracy and reducing the cross interference by obtaining the elements of the tranfer function. Power spectrum plots of the drift force, axial force and torque were obtained so that these plots may be used as a signature. Results show that the ZrN coating is better than the TiN coating because (a) the mean values of the axialforce, drift force and torque are smaller, thus improving the roundness, (b) the dynamic flutuations of the forces and torque about the mean are smaller thus improving the surface quality of the holes produced, (c) the number of holes before the failure of the drill is about three times more for a ZrN coated split point drill as compared to a TiN coated drill. [ABSTRACT FROM AUTHOR]

Two levels of the process planning problem may be distinguished: the local problem, i.e. the production of a single part, and the global problem concerned with the interdependence of a group of parts to be manufactured. At the local level, one is faced with the completeness and the proper sequencing of the required operations. This may be related to the set covering problem and to topological sorting, respectively. The global problem is more involved and two important models are discussed: the process selection model and the FMS scheduling model. The process selection model is formulated as a clique problem. The FMS scheduling model is described as a constrained travelling salesman problem, and for its decomposition cluster analysis is applied. [ABSTRACT FROM AUTHOR]

The loading problem in flexible manufacturing systems warrants the consideration of multiple objectives for effective use of its capabilities. The problem is formulated as a multicriterion programming model. The min-max approach is used to find the solution. The results of a particular example are presented to illustrate the application of the model. [ABSTRACT FROM AUTHOR]

The use of computer simulation to assist in robot selection and programming and to evaluate robotic workcell layout provides the user with an effective tool for planning new robot installations or modifying existing ones. It enables the system planner to examine robot reach and geometry features, calculate cycle time and plan, develop and debug task programs prior to installation. This paper discusses the robot modelling and interactive graphics techniques used in the robot/cell simulation package ROBOCELL. Three industrial robots are used in examples to illustrate the kinematic and geometric modelling, cycle time computation and program features of ROBOCELL. A detailed model of a cylindrical robot is outlined. The application of the simulator for designing a flexible final motor assembly workcell and a packaging/palletising workstation is described. [ABSTRACT FROM AUTHOR]

The paper describes the features and attributes of the CORE requirements analysis tool in a simulation environment and the associated implementation via the FORSS software package. This method is applied to the analysis of a proposed automated manufacturing facility which involves the integration of a power-and-free conveyor system into the paint sprayshop of a manual treatments facility. Practical results for the simulation model are presented. [ABSTRACT FROM AUTHOR]

This paper describes the research currently being conducted at Texas A&M University toward the automated visual inspection of bare printed circuit boards (PCBs) using non-referential algorithms. The first phase of the research includes the development of an efficient algorithm to filter the digitised image of the PCB once it has been received from the camera. The filter enhances the acquired image for easier processing by the system. The research is centred around the use of a commercially available parallel processor to perform this function. The reformatted image is then inspected for defects based on the design rules of the circuit board. [ABSTRACT FROM AUTHOR]

The flexibility of modular fixturing systems can be exploited to significantly enhance the productivity of computer integrated manufacturing facilities. A major impediment to the implementation of this philosophy is the absence of viable methodologies for the automated design and assembly of these fixturing systems. This paper addresses this technological void by proposing a CAD/CAM tool for the automated design and robotic assembly of modular fixturing systems which can form the basis for a fully automated design system. The development of automated flexible fixturing technologies that transcend the traditional time-consuming and expensive practice of manual assembly would significantly contribute to the evolution to the factory-of-the-future. [ABSTRACT FROM AUTHOR]

The results of the applications of design for assembly techniques to two typical designs are presented. Consideration is given to the total product cost and it is found that major cost reductions can be achieved even when assembly costs are relatively small. It is also found that assembly automation becomes more difficult to justify as a product design is gradually improved. [ABSTRACT FROM AUTHOR]

An iterative procedure is presented to solve the process planning problem for robotic assembly systems. The procedure consists of two levels: Level 1-station loading and Level 2-operation scheduling. The main task is to select and load stations and to schedule operations so as to minimise the overall cost of the system with respect to several constraints: (i) time constraints to avoid the bottleneck as well as idle time due to given production ratio, (ii) transportation constraints to avoid returns of the processed assembly to the same station. The procedure is illustrated on the example of modernisation of the system for railcar sides assembly. [ABSTRACT FROM AUTHOR]

Two algorithms are introduced in this paper. The first algorithm deals with surface feature recognition on turned parts. Recognised features are then passed to the second algorithm for NC part program generation. These algorithms have been implemented on a microcomputer to process design/drawing data and prepare NC part programs. The results are satisfactory. [ABSTRACT FROM AUTHOR]

The objective of this paper is to describe a knowledge-based system to assist engineers to generate optimum process plans. The knowledge base is defined using a PASCAL-like language and is maintained in the form of PROLOG sentences. The knowledge base may be readily modified by process planners to meet their specific requirements. An inferece engine systematically tries to apply the rules to generate basic process plans. These plans are then optimised by repeated applications of user difined rules. The system is being written in PROLOG. [ABSTRACT FROM AUTHOR]

The possibilities of the application of ultrasonic sensors for the process monitoring in fluids are described. As an example results, of measurements during polymerisation processes are shown. The ultrasonic velocity v is the measuring, parameter. A pulse travelling method is used. The fundamentals of ultrasound, necessary for the design of ultrasonic devices and the interpretation of the results, are summarised. A smart ultrasonic system for process monitoring on the basis of velocity and attenuation measurements is explained. The limitations of the ultrasonic principle for industrial applications are shown. [ABSTRACT FROM AUTHOR]

This paper describes the formulation and development of a pneumatic sensing device for automated recognition of objects within flexible manufacturing environments. This sensing device utilises a densely packed matrix of IC pressure sensors, providing continuous variable output. The sensing head incorporates a corresponding matrix of air jets which form boundary layers when striking the objects of interest. The back pressure levels from these form the basis for the tasks of object detection and recognition,. Objects and their features are recognised by their 'back-pressure map'. Precise information can be obtained about features and anomalies down to a resolution of 10 μm. The system here described is a research prototype and has been evaluated on a simple test rig: in this form its is not at a stage where it can be applied to a recognition situation on the shop floor. Nevertheless the system is novel and it is hoped to publish details of an industrially applicable package in due course. [ABSTRACT FROM AUTHOR]

A method aimed at the optimisation of the technological process structure and the layout diagram for machining systems based on the optimum variants guided search using designer-computer dialogue has been considered. Mathematical models and results of modelling various machining systems built in accordance with building-block approach are also discussed. The method by which the calculation of productivity and reliability of lines of complex structure can be achieved, based on the generalisation of the modelling, data, and which has been applied to the solution of practical optimisation problems is also presented. [ABSTRACT FROM AUTHOR]

The inspection of parts is a difficult task to automate within the working environment of a factory. Such inspection may be used both for quality control and for purposes of identification. However some parts present special problems, such as those made from transparent or translucent materials. In this case, interpretation of the signal emitted by a low-power laser source facilitates the task of 100% parts inspection and detection of defects. This method has advantages both in cost, reliability and long life, in comparison with other possible solutions. [ABSTRACT FROM AUTHOR]