Possibilities of Software for Welding Manufacture

Votinova E., Ogorodnikova O., Shalimov M.

UralsStateTechnicalUniversity – UPI, Ekaterinburg,Russia

Summary. No doubt, leap forwarding systems for computer engineering are capable to give effective economy of time and material resources during projection and production of new goods, and also to optimize current technologies. In present review the possibilities of different software to support welding technologies are under discussion.

Fast development of software with varied capabilities is promoting formation of new principles in welding management. Use of the latest computer technologies for all-round automation of all weld aspects, including simulation of processes in metal, would allow to save resources and to find the optimal technological decisions quickly.

Any influence of various technological factors on metal is accompanied by heating. Additional heat energy results in thermal stresses, in essential change of thermo-physical properties, in loss of form stability and in other negative phenomena. Wide application of heat sensitive metals in machinery construction was a reason to develop special software for welding. More over, up-to-day tendency of designers to reduce safety factor requires high accuracy during manufacturing welded designs.

Information about distribution of temperature fields enables to choose optimal technology for manufacturing of a product and optimal regimes of its operation, since the temperature alterations during weld operation activate physical and chemical processes in metal, both profitable and disadvantageous ones (e.g. liquation).

Use of computer technologies greatly expands all the capabilities of computing experiment, especially it enables to choose the most suitable variant of technology (e.g. thermal cycle) or to predict defects for welding of diverse metals (e.g. aluminum and steel). The problems listed above do not exhaust all the variety of tasks available for decision by program methods.

In this connection, we could name the main subjects for welding simulation:

  • thermal control during weld operation;
  • heat treatment as a way to remove residual stresses.

The main advantages of the modern software applications are high accuracy of calculation and large volume of output information.

We could classify Russian and world’s software applications according to their main functions up to eight groups as it pointed below.

1. Preparation of the technological documentation by means of CAPP/PDM/PLM systems.

2. Databases: constructive materials, welding materials, normative documents and others.

3. Designing of welded structures by means of CAD systems.

4. Estimation of durability, rigidity, life duration of welded designs by means of CAE systems.

5. Simulation of thermal and metallurgical processes by means of CAE systems.

6. Designing the equipment by means of CAD/CAE systems.

7. Numerical management of welding robots by means of CAM systems.

8. Control systems.

The groups of software applications are listed here in efficient order of their introducing at the enterprise. Let's consider each class of mentioned systems in greater detail.

CAPP

CAPP systems (Computer Aided Process Planning - planning and automated preparation of technological processes using the computer programs) are intended to point the sequence of technological operations and to create the technological documentation in the form of operational and routing maps. These systems are presented in the market by such products as Compass-Vertical (ASCON, St.-Petersburg, Russia); Intermech - TechCard (Minsk, Belarus); ARMSW (Centre ComHighTech, Tula, Russia); ADEM CAM/CAPP (Moscow, Russia); WeldOffice (CSPEC, USA); WeldPlan (Force Technology, Denmark).

Compass-Vertical system for the automated projection of technological processes allows:

  • to project technological processes for various kinds of manufacturing (machining, assembly work, welding etc.) in several automated modes;
  • to perform engineering and technological calculations in the specialized applications (computation of cutting or welding modes and others);
  • to expect material and labour expenses for manufacture;
  • to form complete sets of technological documentation used at the enterprise;
  • to organize and to develop databases for the enterprise using the universal technological directory included in Vertical;
  • to integrate the databases with a control system of the engineering data LOTSMAN:PLM and thus to create the uniform electronic environment for product development and manufacture preparation;
  • to carry out complex automation of technological preparation of manufacture based on the information technologies;
  • to organize on the basis of software presented the optimal interaction of various components in Uniform Information Space of the enterprise. It is necessary, since almost all basic services of the enterprise using a wide spectrum of specialized software are involved in technological preparation of manufacture;
  • to use additional modules of the system for ordering the technological documentation, simplification and adoption of the typical decisions;
  • to organize work of the technologist with the product, and also to support group work on the project as a whole.

Finally, the electronic description of a product contains the complete information required for support of all stages of its life cycle. At a stage of manufacture preparation it’s enable to accumulate the results of design and technological projection and to interchange information between engineering services.

Integration of Vertical and COMPASS-3D (CAD system for three-dimensional modeling) ensures transparent decision of tasks of design and technological preparation of manufacture. COMPASS-3D system allows to organize classical process of three-dimensional parametrical designing from idea to associative solid model, and then from model to the design documentation. Technological system Vertical realizes an opportunity to work with all kinds of the graphical documents - 3D-models, drafts and sketches of products developed in COMPASS-3D, as well as the following methods of technological process designing are realized:

  • projection on the basis of some analogue of the technological process;
  • projection with use of a library of frequently repeating technological decisions;
  • projection with use of a library of design and technological elements;
  • borrowing of the technological decisions from the technologies earlier worked out;
  • a dialogue mode for designing with use of system databases.

The opportunity to choose some optimal combination of design modes is given to technologists working in collaboration with each other.

In this software the essentially new approach to automation of technological process designing, based on application of typical Design and Technological Elements (DTE) and plans of technological processing connected to them is submitted. Any part could be presented by a set of typical design and technological elements, at the same time each element is closely related with the certain set of processing plans. Thus, such set combine both design, and technological information about elements, from which the part consists. It allows to assure automatic transition of options from geometry of a part to technology of its manufacturing. In most cases such set has not the only but some possible plans of processing. To choose the optimal plan, it is necessary to use amplifying parameters. On a design of a product it could be geometrical sizes, values of a roughness or finish, parameters of conjugated surfaces; as for technology it could be material of a part, equipment, adaptations, cutting and the measuring tool.

In the upshot to spell the technology of processing for any element of a part it is necessary:

  • to choose the element from DTE library;
  • to specify values of parameters for chosen element (for example, it is necessary for a hole to enter its diameter, depth and required roughness of surface);
  • to press the button "To receive the plan of processing"; on basis of fixed parameters the system automatically generates probable plans of processing in the form of successive transitions with indication of tool and adaptations needed;
  • to choose a plan of processing from available ones offered by system and to copy it into technological process by double click of the mouse.

The connection of a part and technology of its processing through DTE essentially simplifies technological process designing on the basis of similar technological process. In addition to operations, transitions and equipment (technological process tree) Vertical contains all data about DTE used (DTE tree). There is a bilaterial interrelation between these components – choice of DTE allows to see automatically the plan of its processing; any transition from the plan of DTE processing could be found at once in the text of technology. The removal of DTE is accompanied by automatic removal of the appropriate transitions from technology. The projection of technological process on the basis of similar technological process is reduced to simple editing of DTE set used.

The technologist works in Vertical with several technologies at once as with the usual documents. Having some technological processes open it is possible to arrange them conveniently in a window of system and operatively to use the data for new technological process. The projection of new technology on the basis of similar technological decisions from earlier developed process becomes a fast, evident and convenient operation.

Thus, follows features are realized in Vertical:

  • close integration about COMPASS-3D;
  • operation with all kinds of the graphical documents - 3D-models, drafts and sketches of products designed in COMPASS – directly in a window of Vertical;
  • automatic transition of the draft data (and 3D-model) into the technological process text;
  • connection of the graphical data with structural elements of technological process adjusted by sight;
  • viewing and editing of the plans of processing of DTE surfaces attached to 3D-model elements;
  • guidance in the text of technological process over the 3D-model and-or over the draft;
  • work with various documents including graphical ones created in any САD-system.

Available selection of structure of applied modules for each workplace allows to equip divisions at the enterprises with required software by the best way, and only those modules are established for every technologist which are required to him to assure high-quality results.

The application "wizard of formation of the technological documentation" allows to generate some technological maps or a complete set of maps, and in addition, the forms of maps and the distribution of the data are carried out according to all-union state standards, branch standards and engineering specifications.

The calculating system of welding modes is intended for complex automation of welder technologist work at designing technological processes of welding. The system works like application to Vertical and independently solves the following tasks:

  • the automated selection of modes for the basic kinds of welding;
  • the automated selection of welding materials;
  • computation of rate of welding materials application;
  • computation of power consumption and prime time for technological transition;
  • generation of finished fragments of welding technological process (sets of operations and transitions) over specified parameters of a welded seam and welding technique;
  • adjustment of all parameters and algorithms of data processing for any welded seams and welding techniques.

At designing the technological processes of welding and selection of modes the structural elements of welded seams (State Standard 5264-80, State Standard 14771-76 etc.), displacement of a seam in space used materials (basic, auxiliary), characteristics of the equipment and other necessary parameters are taken into account. The welding technique of the parts could be specified for the whole seam or separately for each layer of the seam; the automated selection of welding materials is possible taking into account the requirements to intergranular corrosion and conditions of welded design operation.

Complete pathway-operational technological process of welding is developed by similar way.

CAD

CAD systems (Computer Aided Design - designing with use of the computer programs) contain modules for modeling of a three-dimensional welded parts, drawing the drafts and creation of text design documentation (specifications, sheets etc.). We could allocate three types of such systems: 1) draft -oriented systems (Compass, AutoCad); 2) systems for solid modeling (SolidWorks, SolidEdge); 3) integrated systems supporting electronic information of a model through all the life cycle of a product, including marketing, conceptual and design engineering, technological preparation, manufacturing, operations, repair and recycling (CATIA, Unigraphics – Siemens PLM Software, Pro/Engineer).

Let's consider more in detail the advantages of CAD SolidWorks, they are as follows.

o Use of its own database including the basic kinds of welds, structural preparation of cutting, limiting deviations and efficient ranges of thickness of connected elements for all types of seams regulated by state standards and the branch specifications.

oOpportunity to design the welds in a context of assembly: the welded seam appears as a new component of assembly been associated with adjacent geometry.

o The designing of frame and girder structures with sections determined by some parameters: "Standard" (All-Union State Standards, ISO or ANSI), "Type" and "Size". Each type of a section includes several standard sizes.

CAM

CAM systems (Computer Aided Modeling - preparation of manufacturing with use of computer systems) represent software packages managing movement of robots at assemblage and its displacement between operations.

For example, ADEM (Russia, Moscow) is used for laser processing and cutting. To create managing programs for welding there is opportunity in ADEM to move laser tool along a volumetric curve with specified focal length and vector of an axis of a laser beam, that allows to achieve five-coordinate processing by the laser. The correction of a corner of beam inclination is supposed during movement along a curve on its separate sections. The change of corners could be made discretely, on each section, or smoothly varied in motion. Wider opportunities are accessible in the laser cutting mode, which is applied basically for processing the thin-walled shells. To set position of the tool and to ensure its perpendicular deduction to the processable shell, it is sufficient to specify surfaces of beam sliding and a set of managing curves.

CAE

CAE systems (Computer Aided Engineering - simulation with use of the computer programs) could be shared into two classes depending on complexity of soluble tasks and qualification of the users.

The vast class of САЕ-programs is intended for the ordinary technologist and allows to solve some applied tasks for the certain kind of welding – e.g. computation of welding mode parameters, definition of material consumption, prediction of mechanical properties of metal in the seam and in the zone of thermal influence, prediction of welded seam sizes etc. Algorithms of such programs are based on simple analytical dependences and empirical models. Working with the applied analytical programs is carried out in the simplified interfaces and does not require large hardware resources. Such programs could be run independently or together with CAD/CAPP-system.

Not numerous, but the important class of САЕ- programs is intended for the highly skilled users (analysts) and allows to solve multiphysics tasks on the finite element meshes (numerical modeling of heat-and-mass transfer processes, physicochemical reactions and metallurgical processes, analysis of electrical fields, analysis of stresses and deformation of a product etc.). The calculating module of the computer program solves by numerical methods the appropriate system of the differential equations describing multiple phenomena different by nature. Such programs could be organized on modular principle, allocating the certain kinds of welding or process models. We could name some of such systems: program package including SPOTSIM, BUTTSIM, MAGSIM, LASIM, CUTSIM modules (ComHighTech – international scientific-educational centre "Computer high technologies for material joining", Russia, Tula); SysWeld (ESI Group, France); SOAR (Sandia Optimization and Analysis Routines for automated welding - National Laboratory of Power Ministry, USA); SORPAS (Swantec, Denmark); VirtualArc (ABB, Sweden). Strength, rigidity, durability, stability of welded constructions could be determined in the well-known universal САЕ-systems: ANSYS, NASTRAN, ABAQUS having special means and opportunity to investigate solid, shell or linear structures.

ComHighTech software allow to simulate the basic weld processes for contact, arc, laser welding and cutting (SPOTSIM, MAGSIM, CUTSIM), and also to automate a workplace of planners (ARMSW).

The ComHighTech product consists of the several software packages allowing to carry out certain functions: MAGSIM – to simulate processes of semi-automatic welding in active protective gases, SPOTSIM – to simulate contact spot welding, CUTSIM – to simulate laser cutting, ARMSW – to create the technological documentation, MEXSW – to analyse mechanical properties of a zone of thermal influence, FLUX 2.1 – to compute the parameters of welding mode under flux.

The package MAGSIM enables to observe influence of welding mode parameters on the quality of weld. It estimates statistically the influence of deflections of welding machine on the quality of the seam, and also automatically defines optimal welding parameters subjected to the selected purpose. It consists of several modules. The module "Analysis" is used for computation of both temperature distribution and seam formation under selected mode parameters. At the same time the input parameters and the output results are recorded, and the seam quality is estimated by European or Russian Standards. The module "Diagnostics" estimates the influence of a welding modes deviation on the result. At that, 2000 simulations of welding are spent at different deviations. Monte-Carlo method used in this module allows to vary deviations of each of three parameters according to Gauss principle of casual dispersion. After statistical processing the received results are classified according to the European Standard EN 25817 and they are graphically represented on the screen. The module "Optimization" serves for reception of optimal parameters for welding mode under the conditions, chosen by the user. Here it’s available to set the purposes of simulation, for example, the maximal speed of welding or optimal formation of a seam. The findings could be printed or represented on the screen in three-dimensional view by axes "arc voltage - welding current - welding rate".

SPOTSIM package is needed to analyse the formation of a seam by contact spot weld of bondings out of low-carbon, unalloyed and chrome-nickel steel sheets of 0,5-5 mm in thickness at use of various electrodes and machines. The SPOTSIM software consists of computer model for contact spot welding, module for process optimization and databases over thermophysical and mechanical properties of steels, over characteristics of welding machines, and over electrode shapes. The model of process numerically solves the system of the nonlinear differential equations for electrical potential and thermal conductivity, and also equations describing plastic yielding of metal and change of a welding current during weld process. The distributions of electrical potential and current density, temperatures, plastic deformations and areas of contacts are computed for each point of time. The thermophysical characteristics of steels serve as input data. The electrical characteristics of the welding machine, including phase angle of thyristors breakover, are taken into account also. As a result of modeling the sizes of cast zone and zone of thermal influence, depth of electrodes cut and gap between parts are determined. Moreover, it is available to estimate probable spitting of liquid metal from weld zone and occurrence of other defects. The simulation results are visualized and recorded. SPOTSIM allows to solve practical tasks of designing and optimization of technology for contact welding, and in particular: estimation of area for allowable welding parameters, estimation of welding stability, choice of optimal process parameters etc.