Chen Guanlong

Study on moving GTA weld pool in an externally applied longitudinal magnetic field with experimental and finite element methods

Under the control of external longitudinal magnetic field, substantial changes happen to ordinary gas tungsten arc welding (GTAW) process. In this paper, mathematical models of fluid flow and heat transfer of external longitudinal magnetic field moving GTAW three-dimensional weld pool were established. Current density distribution on weld pool surface was obtained by probe method. Using the multi-coupled analysis function of finite element analysis software ANSYS, distributions of current density and magnetic field as well as fluid flow and heat transfer in three-dimensional moving weld pool were systematically investigated to understand and reveal the effect of external longitudinal magnetic field on liquid metal in moving GTA weld pool and also to supply basis for the application of external longitudinal magnetic field welding technology.

Study on the drawbead setting of the large deformation area in a trunk lid

Abstract In the stamping forming process of an automotive panel, some defects such as wrinkles and fractures can be eliminated by setting a proper drawbead, such that a successful forming operation can be obtained. The effect of the structure, the geometrical shape and the parameters of a drawbead on the draw restraining force has been analyzed, as also the effect of the draw restraining force on the metal flow in the panel forming process. Some principal guidelines of drawbead setting are summarized for the die-tool design of a panel. The drawing process of a trunk lid is simulated numerically using non-linear finite elements. Referencing the simulation results and the principal guidelines, the geometric shape of the drawbead is adjusted partly, and the material flow is controlled effectively during the drawing process. It is shown that the principal guidelines of drawbead design and the numerical simulation method of the cover panel forming process are reliable.

Curve fitting optimization based on a mixed model for assembly applications

During the final assembly process, finding a best fitting resolution for gap and flush between assembled parts is the main object. This paper divides these fitting problems into two optimization stages, which are attitude fitting and position fitting, and proposes a mixed model which combines the Gaussian Imaging method (Enriched Complex Extended Gaussian Imaging) and even fitting algorithm (Hausdorff distance based criteria). It is illustrated that Gaussian Imaging method can be used to orient two similar curve objects and therefore accelerate the optimization process by the even fitting method. We also demonstrate the model by fitting a 2D classic case, an automobile door fitting into a frame, and generalize the application of the model into 3D curve fitting by fitting a simple automobile lamp into an auto-body. The best rotation and translation is found by using two curve objects’ similarity in attitude and minimum width in gap and flush as criteria.

Application of wavelet analysis to BIW assembly quality evaluation

The exact evaluation of Body-in-White (BIW) assembly quality is an important problem in the process control of BIW assembly quality. The Coordinate Measuring Machine (CMM) has been widely used in the BIW assembly industry. The process of BIW assembly is a non stationary time series. Leap, linear and periodical trends are three mean shifts of CMM data. This paper introduces one simple and applicable method to evaluate the BIW assembly quality with CMM data. Wavelet analysis is employed to separate the trend and variation in CMM data. The practical cases analysed by wavelet analysis prove the effectiveness of using variation to evaluate the BIW assembly quality. The data splitting error is estimated with Monte Carlo simulation.

A knowledge-based approach for calculating setup times

The production mode of high variety and small batches is very popular because it can satisfy various and rapidly changing demands from customers. High variety results in the large and high increasing numbers of product type, which make the traditional Bill-of-Material (BOM) unapplicable because the traditional BOM means a type of item has a unique item number. Earlier researches showed Generic BOM (GBOM) is suitable for this environment. Small batch means the more frequent adjustment of machines, which make setup times to be a un-neglected factor in scheduling. Earlier approaches to obtain setup times are to enumerate all setup times according to experience knowledge. Those approaches should be based on the traditional BOM when they are implemented. As a result, they are not applicable for the high variety and small batch environment. Consequently, after the introduction of GBOM, a knowledge-based approach is proposed to calculate setup times in this paper. And the implementation algorithm is presented then. An application case shows our approach is an applicable one.

MASS CUSTOMIZATION ORIENTED APPROACH FOR VIRTUAL ALLOCATION OF THROUGHPUT AND ITS APPLICATION

Following the analysis of the complexity of the throughput-allocating issue in the group techndogy(GT)-based manufacturing processes,a virtual approach for through- put-allocation is proposed based on the concept of cumulative average turnoff ratio.The approach is then implemented in the Similar Semi-finished products(SFP)delivery planning module of an automatic order-tracing system.A case study illustrates that the module,on one hand,can virtually allocate reasonable similar SFP throughputs to every order in the GT-based manu- facturing processes to facilitate automatic order-tracing,on the other hand,can guide the division of a group of similar SFP throughputs into small sections according to the needs of dif- ferent orders at the customer-order decoupling points,which, therefore,can largely improve the rationality of the delivery plans and can effectively avoid the adverse consequences from unwise throughput-allocating decisions made by human dis- patchers,such as the supplementary production and the delay of the deliveries of some customer orders.

New modeling techniques in multi-space CAD

This paper investigates new wavelet-based multiresolution modeling techniques in CAD. MRA techniques are extended to detail feature transplanting and detail feature copying from previous MRA editing including sweep editing, fractional editing, synthesis editing and detail blending. Two new editing methods called detail feature transplanting and detail feature copying are added to previous sweep editing, fractional editing, synthesis editing and detail blending. Detail feature transplanting editing is a way to transplant detail features of a curve/surface to another curve/surface. Detail feature copying editing is a way to copy or move detail features on the same curve/surface.