« iepriekšējāTurpināt »
(Ex.) High speed Coiling of Stator Core Adaptable to Three types Stator Core
Continuous Coiling Method
(Note that Nissan denied that a goal of high as the expert system did. This cutting by Mr. Harada and Mr. Sugito: design its CAD was to shorten the lead time...) speed was verified in a test. The system for assembly (DFA) and assembly techDesign is supported by NADAMS thus has the capability to solve three nology. The Assembly R&D Group (Nippondenso Advanced Design and problems: lack of experienced process has only five members and was begun Manufacturing System), which has been planners, nonuniformity of their plans, in 1985. Its jobs include interacting under continuous development since and unwillingness of planners to choose with the research community at home 1980. It is written in PL-1 with recent aggressive plans, thus costing time and and overseas, developing ways to simadditions in C. Outside contractors wrote money unnecessarily.
plify products using their own DFA most of it under the leadership of an
methodology, and developing ways to internal group of programmers. It runs Tour of CAE Facility
assemble difficult products that can't on IBM 3090s and supports about 1,000
be simplified. terminals. NADAMS supports 2D and The facility I toured was a training Assembly technology is divided into 3D wireframe models, surface free- center. It contains a wide variety of two parallel efforts: dexterous/intricate form shapes using Coons surfaces and workstations but mostly IBM 5080s. I assembly and large variation assembly rational B-splines, and solid models. saw two demonstrations: tobot offline of simple items (Figure 4). Engineering
All items designed in NADAMS programming and supercomputer out- innovation is used on the first kind are in one database accessible to the put showing FEM studies.
while economic approaches are used designers, including those who design Robot offline programming is on the second because they are already production equipment. Casting and supported by a wireframe 3D modeler technically easy but too costly to molding dies, NC machine operations, that permits a user to build up a model automate. robot programming, operating models of a workstation from basic shapes. A For large variation products, an of parts and products, and simulations primary function of the program is to economic analysis showed that cost of are example applications supported. predict and improve the cycle time of preparing and feeding parts grows much There is an expert system to help devise the robot workstation. The computer faster than other costs as the number of cutting process plans, typical CAE for already has models of Nippondenso's variations grows. Efforts are going into vibration, stress and thermal analyses, various robots (which it makes in-house). various “low cost” feeding and prepamold flow simulations to aid die design, Icould not find out how the coordinateration methods, including an attempt and some fault tolerance analysis soft- data were put in so that workpieces, at low cost bin picking. Bin picking is ware that was not explained further. fixtures, and teach points for the robot being used in only one factory applica
For example, the mold flow pro- could be described. Collision avoid- tion, however. Other applications are gram (IMAP, developed by Toyota ance is done by trial and error, using under development. Reconfigurable Central R&D Laboratories, Inc.) helped the modeler's intersection capability. grippers and pallets are also under Nippondenso reduce the weight of its Straight line paths are computed auto- consideration, along with such air conditioner case and avoid having a matically as a first try and the user
matically as a first try and the user approaches as molding groups of parts hole develop during molding. The modifies them to avoid obstacles or onto one backbone and cutting them number of actual prototypes needed improve cycle time.
off at the moment of assembly. was reduced by 66%.
Several FEM examples were avail- For technologically challenging The metal cutting expert system is able. These include fluid flow in plastic assembly tasks, such as fitting unwieldy, based on Metcut's data plus 650 rules injection molding, turbulent mixing and flexible, and warped items together, provided by Nippondenso's process heat transfer inside the air conditioner Nippondenso long ago concluded that engineers. The rules comprise knowl- between cold and hot air, stress-strain, "intelligent, dexterous, and adaptable” edge about how to process certain and flow inside a fuel manifold. robots were too expensive or unavailgeometries plus formulas for calculat- NADAMS supports pre- and post- able. Instead, they decided to “utilize ing feedrates and tool wear, for exam- processing, and a commercial FEM the characteristics of the product” as ple. The software chooses tool mate- package does the calculations on the well as to redesign the product so that rial and size, cut depth, feedrate, cut- mainframe.
assembly could be accomplished. This ting speed, and cutter rotation rate. In
is another example of the “smart proda side-by-side test, process engineers Developments in
uct” approach. provided process plans for a precision Assembly Technology surface that varied by 4 to 1 in recommended cutting speed. Only one engi- Two interesting activities of the neer recommended a cutting speed as Assembly R&D Group were presented
A fine example shown was fitting the other end of the gap, and the robot fixed portions and variable portions, top and bottom halves of molded plas- pushes and slightly deforms the top suppressing minor variations and using tic air conditioner housings together half until the parts are aligned. Then more common parts instead, and using (Figure 5). These fit by tongue and the pivot-roll method is used to mate the FMS-1 technique. This topic is a groove around a large perimeter the parts while not disturbing the mate subject of ongoing research and Harada (“island”). Since the cases warp, the achieved at the first end of the gap. is gathering more examples from around halves cannot just be pushed together. When there are several gaps, the one in
the company. Fixturing could be used to force the the most flexible region of the case is Twice a year they hold a DFA semhalves into the correct shape but that mated first, then the next most flexible, inar to trade stories, hear advice from would require costly fixtures and/or and so on.
both product engineers and process making the parts too flimsy.
When there is one damper door, the engineers, and teach the method. The problem gets worse when the robot pushes it upright with the top Harada's goal is to create a DFA projoint has a gap (“discontinuity') or two half of the case and catches the door gram based on a solid modeler that will rather than covering the entire perim- hinge in the hole in the case. Then it help product designers evaluate their eter. The worst situation occurs when repeats the tongue-groove method. The own designs. Other companies I have there are “intermediate parts” such as hinge pins on the damper are made asked about such an approach (a subpivoted damper doors where one end extra long so that they do not fall outject of my own research) say that they of the hinge pin fits in a hole in one case during the pivoting operation. When do not believe product designers will half and the other end fits in a hole in there are several doors, this process is ever have the time or knowledge to do the other half. Such doors are placed repeated for each door, and the hinge such evaluations themselves. Harada upright in the lower half but flop over pin of each door is designed to be longer will move to Nippondenso Technical to one side and the hinge pin will not than that of the next door so that the Center U.S.A., Inc. near Detroit and line up with the upper half's hole. sequence of door mates can be con- will survey research opportunities from People currently assemble these trolled.
there. parts. They push and bang the case Whether this scheme can be applied Kimura noted later that both halves together, reaching inside to line reliably and at high enough speed in Boothroyd/Dewhurst (B/D) and Draper up the damper hinge pins and the case the factory is unclear at this time, but Laboratory research on design for assemholes. It is an obvious bottleneck on given Nippondenso's past record, it will bly and simplification of products has the production line and inherently dif- be. It is a pretty sophisticated approach had a strong influence in Japan. The B/ ficult to automate.
and represents “design for assembly” D method is very popular although its The robot solutions have been as high art.
limitations are recognized. demonstrated in the laboratory but not Nippondenso has also developed applied in the factory. They are elegant its own DFA evaluation method. TOYOTA and involve a mix of robot angular Nippondenso's method is broader and maneuvering of the top part, redesign more sophisticated than typical DFA 31 July 1991 of tongue and groove shapes, and methodologies, which most people agree redesign of damper doors. This is the focus too much on small parts. It con- Background approach I called “smart product" above. tains 65 points of evaluation, such as
To fit a tongue-groove that covers how parts must be prepared for feed- My host was Mr. Y. Kuranaga, Head the entire perimeter, the robot tilts the ing, how many variations there are in of Development Div 1 of Information top half and mates the parts on one parts and product, whether a part's Systems Div 1 in the Information Sysside. It then pivots the top half down feeding method supports variety, how tems Division. The entire operation gently by hinging at the initial contact difficult the assembly technique must has 641 people plus at least 330 outside point, and the tongue rolls into the be, and how many parts there are the software developers. Its mission is to groove.
most important item). Production develop and disseminate software for When the joint has a gap, the above engineers perform the evaluations and engineering, business, and factory method is used, starting at a pivot point give advice to the product designers. operations, plus to provide software opposite the gap and rolling around so An interesting redesign activity is training. Toyota has agreements with that the parts are mated at one end of called variation reduction. Its aim is to several companies such as Nihon Unisys the gap. A vision system is then used to reduce the effect of multiple models on to support and sell its CAD software to find the top in relation to the bottom at the assembly processes. Methods used Toyota's vendors.
include modularizing the product into