Gary P. Maul

A systems model and simulation of the vibratory bowl feeder

Abstract Vibratory bowl feeders are the most versatile and widely used parts feeders in automated assembly. This work develops a mathematical model of a bowl feeder by using state-space methods to evaluate bowl feeder parameters. From the mathematical method, a computer simulation can predict the velocity of the parts in the bowl and subsequently the part feed rate. The simulation might be used to improve the design of vibratory bowl feeders.

Sensor-based solution to contiguous and overlapping parts in vibratory bowl feeders

Abstract This paper discusses a vibratory bowl feeder with a computer-based sensor system that can recognize correctly oriented parts even when some are configuous or overlapping. Hardware consists of a vibratory bowl feeder, sensor system, control computer, and software development computer. The sensor system is a linear row of film optics in the side wall and track of the bowl. This configuration createsa 3-D silhouette of the part. An algorithm is developed to recognize parts in the orientation specified by the user. Test results show that the control program functions very well.

A novel, low-cost pneumatic positioning system

Applications requiring accurate position control are in increasing use in industry. Pneumatic servo systems can provide a clean, accurate, robust positioning system; however, the proportional valves used in such systems are relatively expensive. The use of solenoid valves to replace a proportional flow control valve can significantly lower the price of a positioning system. This substitution is possible if the solenoid valves are operated using a pulse-width-modulated (PWM) control scheme. This work presents a design in which position control is realized on a single-rod, double-acting cylinder. Two solenoid valves operate conventionally to fill either chamber of the cylinder, while a third valve uses pulse-width modulation in metering the exhaust flow.The experimental apparatus is capable of positioning a load along a horizontal axis to within ±0. 10 mm.

A method for robust process design based on direct minimization of expected loss applied to arc welding

Abstract Robust process design seeks to maximize the process performance, taking into account uncertainty in the “noise” factors that cannot be controlled. A methodology for robust process design is presented that is based on direct minimization of the expected loss. The proposed methods are compared with alternatives, including methods based on Taguchis signal-to-noise ratios. Several formulations of the expected loss are explored, including formulations that account for losses from parts inside the specification limits and that permit the use of deterministic optimization methods. The method is illustrated through its application to the design of robotic gas metal arc welding (GMAW) parameter settings.

Flashless closed-die upset forging-load estimation for optimal cold header selection

Abstract In cold forming operations, the two primary considerations in determining process feasibility are load and energy required to form the part. These two factors determine the press size and therefore the maximum production rate. Close estimations of these values during the process planning stage allow for accurate machine sizing and lead to higher efficiency. However, methods for estimating forming loads and energies of flashless closed-die upsets are not well researched. The objective of this study was to develop guidelines for this purpose. Experiments were conducted to measure the load during many flashless closed-die upsets. These results were compared to predictions made using a mathematical model (modified slab method) and an FEM analysis (DEFORM 2D) to gauge the ability to accurately predict forging loads. Additionally, FEM was used to study the sensitivity of the forging load to friction conditions, part size, and average material strain. The results indicate that the modified slab method predictions are quite accurate in some cases but overestimate the load by as much as 35% in others. The DEFORM 2D load predictions are more consistent but generally underestimate the load by 5–20%.

Optimal injection velocity profiling

Recently, manufacturers of thermoplastic injection moulding machines have developed controllers with programmable velocity control. The speed of the ram can typically be varied in as many as ten zones during the injection process to establish a velocity profile. This velocity profile however, is determined by trial and error. Some controller manufacturers have made claims about injection velocity profiling, however, actual experimental data is not available to confirm them. In this paper, some experiments were conducted in order to verify the effectiveness of these claims. The results of these experiments indicate that injection velocity control has little effect on reducing or eliminating the problems for which the claims are made.

A Methodology for Developing Programmable Part Feeders

Abstract Parts-orienting devices have long been recognized as critical elements of mass production systems. In batch manufacturing, workpiece orientation has typically been accomplished manually because a parts production volume usually does not economically justify the design and construction of a dedicated parts feeder. Different approaches to workpiece orientation have been undertaken by various researchers. This paper discusses some of those approaches and offers an alternative approach consisting of a methodology for developing programmable feeders based on conventional parts-feeding technology.

Development of a model for part reorientation in vibratory bowl feeders with active air jet tooling

Abstract Vibratory bowl feeders (VBFs) are widely used in industry for feeding and reorienting small parts in high volume production. Standard VBF tooling consists of various mechanical barriers inserted in the bowl path which are prone to jamming and limit the feeder to only one type of part. Programmable feeders have been developed to improve the flexibility of these devices, however feed rates are often low. This research describes the development of a model of part behavior required for reorienting a part with an air-jet-based computer controlled orienting system. This system can be used to eliminate jamming and improve feed rates in VBFs. The control algorithm accepts the parts weight, geometry, and its orientation. Sensors then compare the present with the desired orientation and the algorithm determines the appropriate pulse of air to produce the desired orientation.

A computer analysis of orientation devices for vibratory bowl feeders

Currently, vibratory bowl feeders are widely used in industry to feed small parts in assembly processes. The actual orientation of parts is achieved by various devices used in these feeders. However, each type of device performs only a limited function. The objective of this project was to develop a systematic approach which both analyses the geometrical and topological properties of parts designed in a CAD system and selects appropriate orientation devices to feed the designed parts.

Research for low-cost flexible feeding of headed parts using bi-directional belts

Part orientation for flexible manufacturing and assembly can be approached in several different ways. This paper reviews some approaches currently being developed and describes a potentially inexpensive method for the flexible feeding of headed parts. Utilizing adjustable tooling mid bi-directional belts to achieve part orientation. Some experimental observations of the feed rate for headed parts relating to feeder design are also discussed.