Papers by Keyword: In-Process Measurement

Abstract: The impregnation represents a crucial phase in liquid composite molding (LCM) processes. Researchers over the years have used various approaches for monitoring, based on smart weave, pressure sensors, dielectric. Among the LCM processes, the vacuum bag allows the use of visual systems for detecting the resin flow front. The integration of monitoring systems with controllers for automated management of process parameters leads to an improvement in the characteristics of the final manufactured component. In the present work, an AI-based system integrated with the control of a resin preheating system allows for improvement of the impregnation stage. A machine learning approach, based on the You Only Look Once (YOLO) algorithm, has been integrated with the visual monitoring system to detect and dynamically track the resin flow front in real time. The flow front position has been compared with the theoretical one, evaluated by using the Darcy’s law and based on the mismatch the controller suggests a proper in-time regulation of microwave power. The implemented system is capable of processing images through an AI-based algorithm and extracting the kinematic data of the flow front and integrating the information from the thermocouples and the visual system to control the microwave power.

Abstract: This paper proposes to improve the form accuracy of a machined surface produced by an ordinary milling machine by diamond fly cutting using controlled cutting with reference surface (CCRS), an in-process measurement and control method. CCRS improves machined surface accuracy by controlling the relative displacement between the tool and workpiece. Diamond fly cutting using CCRS was demonstrated to reduce the table motion error on an ordinary milling machine.

Abstract: The energy efficient, high-speed laser deep penetration welding process is a technology which is increasingly used for industrial applications. In order to guarantee weld seams of high quality a stable process needs to be established. Especially when welding aluminium alloys the weld quality is reduced due to occurring spatters which entails a loss of material. Solidified spatters remain on the surface of the specimen after welding and need to be cleaned for further processing steps. One method to change the process behaviour is beam shaping. In this work, a bifocal optic is used to produce two foci along the beam axis in order to manipulate the energy input into the keyhole. Bead-on-plate welds are produced in aluminium alloy EN AW-6082 and mild steel S235. For comparison, welding is conducted using standard optics. The spatter occurrence is compared when using these different beam shapes. While a reduced number of spatters per time are observed the spatter size increases when using the bifocal optic in this study.

Abstract: A rising trend to miniaturization and function integration requires new materials, tools, manufacturing setups and quality inspection strategies for mass production of micro mechanical systems (MMS). In most scenarios, quality inspection is carried out manually. An expert takes samples out of the manufacturing process and investigates them by means of tactile or optical measurement systems. This time consuming quality inspection process leads to low inspection rates, especially in bulk manufacturing processes, where manufacturing frequencies of 400 parts per minute are common. This contribution introduces an automated optical quality inspection method based on a digital holographic system, which acquires 2D texture and 3D shape information in one single measurement step. Based on 3D data, an automated point separation algorithm splits the measured object shape into elementary geometries and calculates form and position deviations compared to an object model. In the final step, a 2D surface inspection procedure based on multi-scale texture analysis detects surface defects with respect to the separated elementary geometries and fuses the result from the 3D shape and the 2D texture analysis to a final rejection decision. The capability of the proposed quality inspection method is demonstrated in a micro cold forming scenario, where a micro cup smaller than 1 mm in all geometric dimensions is the object under investigation.

Abstract: The dimensions of a workpiece have been measured during the milling process using a 3D laser inspection system. Re-clamping of the work piece has been avoided but a short interruption of the milling process took place. All three dimensions of the part have been measured, height and width using a profile scanning devise based on the laser triangulation method and the length using also the displacement features of the machine tool. Gauge blocks with the reference dimension of 4, 8, 10, 14, 18 and 23 mm have been used for the verification of the measurements. The measured values for the height deviate from the real value between 0 to 19 μm. The deviations of the length lie between 0 and 33 μm. The deviations of the width are higher and they lie between 0 and 150 μm, because of the scanning steps of the devise. The measurement of the width could be improved using a second scanner perpendicular to the first one in order to achieve an overall part inspection with deviations lower than 33 μm.

Abstract: In cylindrical grinding, a sizing device is generally used to obtain the required dimension. However, the dimensional error can be caused by the thermal deformation of the workpiece even if grinding machine is controlled with the sizing device. To solve this problem, it is necessary to develop the grinding system that can consider the thermal deformation of the workpiece during grinding process. In this study, an advanced grinding system was developed, which can predict the net stock removal of ground workpiece immediately. The grinding experiment is carried out to verify the developed system.

Abstract: A wavelength scanning interferometry system for fast areal surface measurement of micro and nano-scale surfaces which is immune to environmental noise is introduced in this paper. It can be used for surface measurement of discontinuous surface profiles by producing phase shifts without any mechanical scanning process. White light spectral scanning interferometry, together with an acousto-optic tuneable filtering technique, is used to measure both smooth surfaces and those with large step heights. An active servo control system is used to serve as a phase compensating mechanism to eliminate the effects of environmental noise. The system can be used for on-line or in-process measurement on a shop floor.

Abstract: With STEP-NC providing a way for seamless integration of the design, manufacturing, and quality control processes, the implementation of in-process measurement in this context has become a necessity for STEP-compliant NC manufacture. In the light of current research and development trends in this field, this paper proposes an approach to on-machine planning for in-process measurement, focusing on touch probing operations. Issues about the measured elements and the probing path planning are mainly addressed, and a prototype system is designed and implemented, which generates probing paths based on the information contained in the STEP-NC part program. The feasibility of the proposed approach is demonstrated with an example STEP-NC file.

Abstract: The purpose of this study is to develop an in-process of measurement technique of surface roughness using thermoelectric effect in cylindrical grinding. The electromotive force (EMF) generates depend on the surface roughness of workpiece and the variation of workpiece temperature when the sensor with thermocouple wires rubs on the workpiece surface in grinding process. In this paper, the in-process measurement technique of surface roughness in cylindrical plunge grinding is proposed, conceiving the cancellation of the EMF caused by the variation of workpiece temperature in the sensor output. Also a new type in-process sensor was developed for high accuracy to overcome the problem which was clarified in the cancellation method of the influence of workpiece temperature at a basic sensor.

Abstract: In order to allow optical signals to reach the workpiece surface to realize in-process optical measurement through an opaque coolant, a locally transparent region generated by use of an air beam is examined to allow better understanding of the fluid assisted in-process optical measurement approach. With the air beam used, the problems associated with the diluting effect on coolant concentration and the measurement error due to the optical transmittance through multiple media can be avoided. The working principle and the experimental results for testing the proposed method are presented and discussed.