Small Mechanical Parts Research Articles

A variable-measurement-space-based method for improving the measurement accuracy of AACMMs

Articulated arm coordinate measuring machines (AACMMs) are usually used to measure mechanical parts of different sizes in practical applications. When the size of parts is smaller than that of the AACMM, a redundant measurement space of the measuring machine is generated, resulting in reduced measurement accuracy of the AACMM. Moreover, due to the series structure of the AACMM, the joint errors would be propagated with the increasing length of the bar, which could amplify the measurement error. Therefore, on the premise of ensuring the measurement space required by the measured parts, this work proposes a new method based on variable measurement space, i.e. locking some movable joints of the AACMM, to improve the measurement accuracy of the AACMM for small mechanical parts. The measurement accuracy of the AACMM is examined under various measurement spaces. Firstly, the Monte Carlo method is used to simulate the measurement space of the AACMM with one or more joints locked. Then, the spatial error of the AACMM and the multipoint calibration with joint locked are simulated and discussed in detail. Finally, the feasibility and effectiveness of the proposed variable-measurement-space method are verified by the standard single-point cone experiments. The results show that the measurement accuracy of the AACMM is substantially improved under three kinds of strategies, i.e. locking joint 1, joint 2, and joint 3, respectively.

Three-Dimension Measurement of Mechanical Parts Based on Structure from Motion(SfM) Algorithm

Background: As an important branch of computer vision, visual measurement is a fast developing cutting-edge technology, which has been widely used in the manufacturing field. In recent years, the visual measurement of feature size of probes through small IC probes has aroused wide concern. Objective: This study aims to take small shaft parts as the research object in order to provide a full set of novel and reliable technical means for the three-dimension measurement of mechanical parts. Methods: Firstly, the trinocular vision measurement system based on the curved cantilever mechanism was designed and constructed. Secondly, the measurement system was used to collect the part images from different angles, and the images derived from the four categories of segmentation algorithms such as threshold-based, region-based segmentation algorithm were compared and analyzed. Lazy Snapping image segmentation algorithm was used to extract the foreground parts of each image. After comparing and analyzing SfM-based algorithm and Visual Hull-based algorithm, the SfM-based algorithm was adopted to reconstruct the 3D morphology of the parts. The measurement of the relevant dimensions was performed. Results: The results shows that Lazy Snapping's human-computer interaction brush function improves the accuracy and stability of image segmentation of different algorithms, such as threshold value method, regional method, Grab Cut, and Dense Cut. The SfM-based 3D reconstruction algorithm is of high robustness and fast speed. Conclusion: This study provides an effective method for measuring small mechanical parts, which will shorten the measurement cycle, improve the measurement speed, and reduce the measurement cost.

High-capacity rotary drum for atomic layer deposition onto powders and small mechanical parts in a hot-walled viscous flow reactor

Atomic layer deposition (ALD) is uniquely capable of providing uniform thin-film coatings on powder substrates, but powder processing has historically required an ALD reactor designed specifically for powders—e.g., a fluidized bed. Tubular hot-walled viscous-flow reactors commonly employed in laboratory-scale ALD research for coating planar substrates such as silicon have been employed previously to coat gram quantities of powder spread out in a thin layer on a tray, but larger quantities of powder introduce long diffusion pathways where reactants are unable to percolate to the bottom of the powder bed to provide uniform coating in reasonable time periods. In this work, we report a rotary drum with a capacity of 100s of grams that is compatible with conventional tubular hot-walled ALD reactors and provides uniform coatings on powders in viscous flow operation. We benchmark this system using Al2O3 ALD with trimethylaluminum and water. We examine the effect of rotation speed and powder quantity on saturation time via in situ quadrupole mass spectroscopy measurements and gravimetric analysis. The rotary drum we report is able to provide homogenous coating of up to 75 g of silica gel powder with a total surface area of ∼1500 m2 in viscous flow operation with precursor utilization as high as 70%.

Design of Mechanical Structure of Punch Feeding Manipulator

In this paper an automatic feed manipulator for automobile stamping is introduced. It can achieve the process cycle for various cars parts manufactured such as automatic grab, loading and blanking, which is suitable for the large quantities and small mechanical parts material process. The primary purpose of this article is to present the manipulator structure and to design the virtual prototype of the manipulator. The calculation and optimization of stress and strain are carried out for the robot key moving parts by the analysis of the movement process and sport principle. Compared with the multi-joint robot, its manufacture, control requirements and the cost are low. The robot is suitable for large quantities and small parts process.

バラ積みピッキングのための部品認識手法の基礎検討

Bin picking technology is one of the today's important topics, which realizes efficient production process. In this research, we considered a parts recognition method for small mechanical parts with a complicated shape and occlusions. In this paper, we will report the results of basic experiments of parts recognition.

INVESTIGATION OF THERMOFORMING TOOL DESIGN AND POCKET QUALITY

Thermoforming is widely used in manufacturing industries to produce a range of polymer products. The Reflex tape thermoforming system is designed to form flat tape film into pockets. These formed pockets, also called carrier tape, are used in numerous applications to package a large variety of electronic or small mechanical parts. Thermoformed pocket walls are generally not uniform in thickness and often break during the forming process. Uniform wall thickness distribution, especially for deep pockets, plays significant role on pocket quality improvement and scrap reduction. This paper investigates the influence of the tool design, tool material, and some thermoforming process parameters on wall thickness distribution in formed pockets using polymer flat films. Conventional tool and a hybrid tool with 3d printed inserts were used in the experiments. The process parameters, plastic film and tool set temperatures were controlled by the Reflex machine and also measured using infrared thermometer and thermocouple. Film temperature ranges from 150 to 200 °C and a range of tool set temperatures (40 to 85°C) were used in the thermoforming. It has been found that the temperature difference between the plastic film and the forming tool was important for uniform wall thickness distribution. The results from this experimental study concluded that the most influential factors for good pocket quality are the tool design, tool material, and heat transfer dynamics in the plastic film - tool set system. Another aim of the study was to investigate the viability of the 3D printing process to manufacture rapidly tool inserts compared to conventional CNC machining.

Entire Hardening of Small Thin Plate with a Small Power Semiconductor Laser Considering Plate Deformation

Nowadays, resource saving technologies have become important because of increasing global environmental problems. Moreover, demand is increasing for the manufacturing and machining of small mechanical parts because of the downsizing of electronic mobile devices. Thus, one requirement has emerged that these small parts have to be fabricated by smaller machine tools to reduce the environmental burden. Here, when we look at the heat treatment process, it is found that most small parts are generally treated with a large size furnace as well. Therefore, we focus on compact machine tools to develop the clean and energy-saving technology in the manufacturing fields. In the present report, we consider an in-situ laser heat treatment technology integrated on the table used for compact machine tools. In particular, we perform the entire laser hardening of a small thin plate with a small power semiconductor laser, which is an attempt to harden a whole steel sheet. However, thin plates deform during the laser hardening process, which is called “laser forming.” Thus, we discuss an effective irradiation path to prevent the deformation of plates while quenching the entire plate. Moreover, considering the power consumption in the laser quenching process, we investigate an appropriate laser irradiation condition.

Development of Whirling Electrical Discharge Texturing on Inner Surface of Small Hole

The tribological characteristics of sliding parts can be controlled by creating a microstructure on their surface. However, the effect of microstructures on the surface of a small hole of an inner sliding part or a hardened part has not been investigated. Thus, an efficient method, electrical discharge texturing (EDT) was previously developed to create a microstructure using a single discharge. In this study, whirling electrical discharge texturing (whirling EDT: WEDT) was developed as a method of creating microstructures on the inner surface of small holes and mechanical parts made of high-hardness materials. It was examined whether the WEDT equipment can be used to texture the inner surface of small holes and high-hardness materials. In addition, the fundamental characteristics of WEDT were studied. It was verified that, it is possible to create microstructures via the whirling phenomenon and single discharge of WEDT. The shape and texture-area ratio can also be controlled by WEDT, where the texture-area ratio is controlled by varying the feed speed.

High Efficiency and Eco-Friendly Heat Treatment of Small Parts with a Low-Power Diode Laser Beam

Demand is increasing for the manufacturing and machining of small mechanical parts. We focus on using a multi-functional desktop-sized machine tool to meet such demands because power consumption is decreased when they are machined. However, few reports have focused on heat treatment among manufacturing processes, we investigate the laser heat treatment of small parts as a highly efficient and eco-friendly method and propose in-situ heat treatment on a desktop-sized machine tool using a low-power diode laser beam. We quenched a small thin steel plate with a 30 W diode laser source. Our proposed method makes it feasible to quench a small thin steel plate and effectively reduces the power consumption of in-situ heat treatment by a desktop-sized machine tool.

2-D Circle Measurement System for Small Rule Parts Based on Machine Vision

A Circle-shape is an important figure in most small rule mechanical parts, and usually be measured to get the radius or used as a stand calibration mark. In this paper, a 2-D circle measurement system for small rule mechanical parts based on machine vision is designed and built. The basic components and work principle of the machine vision measurement system are introduced, and the measurement produce is designed and discussed. An available algorithm for circle contour detected and fitted is described. Using this algorithm, the measurement software flow and architecture are built and the software system realized in the Microsoft visual studio program platform. Certainly, the calibration of machine vision system is introduced also. Using the system and method introduced above, an experiment is designed to measure the outer ring radius of one certain model bearing. The measured data is processed and analyzed. Through the experiment and result, it can be found that the measurement system can get relatively high precision and the measurement method is relatively steady, and the system precision and speed can be suit for the demand of on-line and real-time circle measurement.

Three-dimensional measurement of small mechanical parts under a complicated background based on stereo vision

We present an effective method for the accurate three-dimensional (3D) measurement of small industrial parts under a complicated noisy background, based on stereo vision. To effectively extract the nonlinear features of desired curves of the measured parts in the images, a strategy from coarse to fine extraction is employed, based on a virtual motion control system. By using the multiscale decomposition of gray images and virtual beam chains, the nonlinear features can be accurately extracted. By analyzing the generation of geometric errors, the refined feature points of the desired curves are extracted. Then the 3D structure of the measured parts can be accurately reconstructed and measured with least squares errors. Experimental results show that the presented method can accurately measure industrial parts that are represented by various line segments and curves.

Scheduling of unrelated parallel manufacturing cells with limited human resources

In this paper the scheduling of batches of parts within a manufacturing system consisting of M unrelated parallel CNC manufacturing cells and employing a limited workforce capacity is investigated: the objective is to maintain the number R of available workers lower than the number M of the cells leaving unchanged the whole system output. Each cell of the system consists of a CNC machining centre which works batches of small mechanical parts, grouped together on a common pallet in accordance to the group technology principles. Batch splitting among CNC cells is not allowed and the setup time required by each batch is both sequence and cell dependent. The setup activities are fully performed by the workers employed within the manufacturing system; the working operations within the CNC cells are completely automated, thus the workers tasks are restricted only to the setup operations. The effect of reducing the human resource capacity on scheduling of parts within cells, and on several process performance measures, is investigated through an extensive design of experiment involving different process scenarios. The process activities and resources dynamics are simulated and optimized by means of an integrated simulation framework, consisting of an object-oriented simulator interfaced with a heuristic procedure, designed within the eM-Plant™ software environment. The obtained results show how the human resource can be maintained significantly lower than the number of cells without affecting the output of the manufacturing system.

Development of Multi-functional Mini Machine Tool Integrated Heat Treatment Processes(Advanced machine tool)

In recent years, desktop machine tools or multi-functional machine tools have attracted attention for cell manufacturing system. In this study, we attempt to develop the multi-functional mini machine tools with a laser heat treatment function. In the present paper, we made a prototype mini machine tool with a table drive stroke of 50mm, for the multi-functional mini machine tools. First, we evaluated the motion accuracy, the power consumption and the heat deformation of the prototype mini machine tool. Second we examined a laser source to perform the heat treatment of small mechanical parts on the machine tool table. As a result, the prototype mini machine tool was found to be effective integrating manufacturing processes on the desktop table.

Consturction and Evaluation of Micro-Object Manipulation System with Concentrated Motion.

In this paper, a design concept of a micro object manipulation with concentrated motion is proposed. Based on this concept, a micro-handling system is realized, and evaluated by means of some micro-object handling operations. This consists of a concentrated motion manipulator, a worktable and optical microscopes. In micro-object handling, it is most important that alloperations are always executed within the visual field of a microscope. To enable task execution within the visual field, a tool tip must always remain within the visual field, i. e., D. O. F. of the manipulator must essentially be configured so that all rotational centers of D. O. F. coincide with each other at the tool tip. Using this system, we succeeded in several micro-object handling operations such as assembly of a micro-torii (shinto shrine gate) and a micro-air turbine (dia. 500μm) as examples of assembly of small mechanical parts, and folding of a micro-origami (paper folding)airplane as examples of handling flexible objects. The capability and effectiveness of this configuration are confirmed by these experimental operations.

常圧及び加圧焼結のメカニズムとニヤネットシェイプ制御 ステンレス鋼圧粉体の焼結収縮挙動の数値解析

Sintering shrinkage behavior is numerically simulated on stainless steel powder compacts prepared by metal powder injection molding (MINI). The MIM process is now highlighted because of its near-net-shape productivity of small mechanical parts having complex shape along with high relative density. In general, however, the initial packing density of the compacts is rather low to be around 55vol.% in relative density. This should cause large volume change during sintering, resulting in the possible nonuniform shrinkage in the compacts. Thus, in the MIM process, the prediction of geometric change of a compact is of extreme importance.The numerical simulation involves finite difference analysis to determine temperature distribution in a compact set in a vacuum furnace, densification analysis by use of sintering rate equations, and finite element analysis to convert the shrinkage into the geometric change of the compact. Six rate equations for sintering mechanisms summarized by M.F.Ashby are used for the calculation. We have assumed that the six mechanisms are distinguishable and sintering rate is the sum of the six rate equations. It has been demonstrated that the density inhomogeneities due to local temperature differences contribute to the nonuniform shrinkage in the early stage of sintering; however, it attenuates reversely in the final stage.

Design and Application of a Prototype System for Concurrent Engineering in a Small Firm

Efforts to develop an integrated or concurrent engineering approach to design and manufacturing often focus on large systems in large firms. However smaller firms can also benefit from this approach. In this paper we propose a database structure for handling the design of small mechanical parts to be produced on a flexible manufacturing system. The database collects the information on geometric models of part designs, models for tools and fixture. manufacturing operations and detailed process plans which are developed simultaneously. This prototype database structure and planning system have been developed to run on an IBM PS/2 or equivalent. This paper outlines the data structure design and the planning assumptions that are made to implement such system. The system is illustrated by applying it to realistic part designs.