2019年92午夜视频福利

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        Sheet metal structural welding deformation control and correctio

        Number of visits: Date:2015-08-04 15:26:20

        Sheet metal structural welding deformation control and correction

         

        I. Introduction

        Foil structure generally refers to structures with a thickness of not more than 4 mm of steel (including stainless steel, galvanized sheet, tin) from the welding. During the welding process, will inevitably produce some variations, the following were discussed and corrected for distortion control.

        Second, the reason for welding deformation of

        Arc welding is a non-uniform rapid heating and cooling process, and after the welding process, welding member will be deformed. Effect of welding deformation of the most fundamental factor is rigid conditions during welding and thermal deformation of welded components. Thermal deformation during the welding process by means of rigid constraint conditions, the emergence of compression plastic deformation, which resulted in residual welding deformation.

        Second, the reason for welding deformation of

        Arc welding is a non-uniform rapid heating and cooling process, and after the welding process, welding member will be deformed. Effect of welding deformation of the most fundamental factor is rigid conditions during welding and thermal deformation of welded components. Thermal deformation during the welding process by means of rigid constraint conditions, the emergence of compression plastic deformation, which resulted in residual welding deformation.

        Second, the reason for welding deformation of

        Arc welding is a non-uniform rapid heating and cooling process, and after the welding process, welding member will be deformed. Effect of welding deformation of the most fundamental factor is rigid conditions during welding and thermal deformation of welded components. Thermal deformation during the welding process by means of rigid constraint conditions, the emergence of compression plastic deformation, which resulted in residual welding deformation.

        (A) factors affecting the weld heat distortion

        1. welding processes. Different welding methods will produce different temperature field, thermal deformation of form is not the same. In general, automatic welding over manual welding heat concentrated, narrow heat affected zones, small deformation. CO2 gas shielded welding wire thin, high current density, centralized heating, deformation. 2. welding parameters. That is the welding current, arc voltage and welding speed. The greater the energy line, with the welding speed increases. In the three parameters, the action of the arc voltage significantly, and therefore a smaller low voltage high current density, high-speed automatic welding deformation. 3. The number and cross-sectional size of the weld. The number of welds, the greater section size, the greater the welding deformation. The construction method. Continuous welding, intermittent welding different temperature field, thermal deformation is different. Typically continuous welding deformation of large, intermittent welding distortion to a minimum. 5. thermo-physical properties of materials. Different materials, thermal conductivity, specific heat and not the same expansion coefficient, thermal deformation is not the same, not the same welding deformation.

        (B) factors affecting the stiffness coefficient of welded components

        Size and shape of a member. With the increased rigidity member, welding deformation is smaller. 2 tire clamp applications. Using fetal fixture, it increases the rigidity member, thereby reducing welding distortion. 3 assembly welding program. Assembly welding program can cause changes in different stages of assembly member in a rigid position and center of gravity change, have a great impact on the welding deformation control member. In general, welded components under conditions of constrained small welding deformation, on the contrary, the deformation.

        Third, the sheet metal junction structure welding deformation species

        Any steel welding deformation can be divided into the overall deformation and local deformation. Change is the overall deformation after welding, size or shape of the entire component, which includes the longitudinal and transverse shrinkage (total size shortening), bending (hogging, sagging) and twisted

        Deformation. Local deformation refers to deformation of welded components of local area later emerged, including angular distortion and wave deformation.

        Fourth, the control sheet junction structure welding deformation of Principles and Methods

        During welding thermal deformation and rigid conditions applied welding member are two main factors affecting the welding residual deformation. According to these two main factors be considered residual welding deformation is inevitable that the complete elimination of welding deformation is unlikely. Control of welding residual deformation must be taken from the design and construction process foil structures both at the same time.

        In addition to the design of sheet metal structure to meet the strength and performance of components, but also must meet the minimum welding distortion and the minimum requirements for component manufacturing in the cost of labor hours. Therefore particularly important to optimize the slab layout, design drawings seams are often arranged on the process of the ill-considered likely to cause welding deformation.

        Welding process is an important process of steel construction. Reasonable welding to reduce welding deformation is an effective way to reduce stress concentration.

        In order to control welding distortion components, effective measures should be taken as far as possible, such as: the member is divided into a number of small parts and components segment, the welding deformation scattered in various parts, to facilitate member deformation control and correction; so that all parts of the weld layout and component sub-sectional or near the neutral axis of symmetry cross-section of the neutral axis, to avoid excessive distortion after welding and bending deformation; for every major weld possible, choose small size and short fillet weld; Weld avoid over-concentration and cross layout; wide and long as far as possible to reduce the number of plates or weld formal structure, and so on.

        A process control sheet structure welding deformation are:

        (A) of the assembly member assembly in the absence of compulsory under stress;

        (Ii) the use of automatic welding and other GMAW processes; as the most advanced MAG Ar + CO2 mixed gas shielded arc welding.

        (C) a reasonable choice of welding parameters and welding sequence assembly. Reducing the wire feed rate, to reduce the current, voltage, polarity change (typically reverse polarity DC DC positive polarity). Short after the first welding seam weld length, take back-step welding, sequentially from the inside outward.

        And (4) reasonable use of rigid fixation, anti-deformation method.

        Reasonable choice of welding parameters and welding sequence assembly. Reducing the wire feed rate, to reduce the current, voltage, polarity change (typically reverse polarity DC DC positive polarity). Short after the first welding seam weld length, take back-step welding, sequentially from the inside outward. And (4) reasonable use of rigid fixation, anti-deformation method.

        Fifth, the foil structure welding deformation correction

        Steel structure construction process, although the measures taken in its design and construction process means to control welding distortion, but due to the characteristics and construction technology of welding process complexity, the welding deformation is still inevitable, therefore, appear beyond welding deformation design requirements must be corrected.

        Correction process is limited to the local distortion correction welded components, such as angular distortion, bending, wave distortion, etc., the overall structure of the deformable members such as longitudinal and transverse shrinkage (total size shortening) than pre-release only through cutting or assembly amount to compensate.

        Mechanical correction method correcting metal work hardening steel prone to consume a certain amount of plastic material reserves, only good for the plastic material, the actual production, mechanical correction of the correction process may use a dedicated large hydraulic machine, friction pressure machine correction.

        With Flame straightening correction steel, correct cooling, welding components that part of the metal get irreversible compressive plastic deformation, so that deformation of the welding member be corrected. Flame straightening also have to consume part of the plastic material, for brittle materials or plastic material difference to be used with caution. To properly control the temperature of the flame heating, lower-temperature mechanical properties of materials, the temperature is too low to make the correction efficiency. The cooling rate does not have any impact on correction effect, the construction process, the use of water cooling while heating methods, both to improve the work efficiency, and improve the correction.

        In summary, the steel manufacturing process, welding deformation is inevitable, but to take effective method, measures to control the welding deformation and welding deformation beyond tolerance is corrected so as to meet the quality requirements of steel, and meet economic requirements.

        TypeInfo: Media reports

        Keywords for the information:Welding deformation 

        2019年92午夜视频福利
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