Slow wire walking, also called low-speed wire walking, is a kind of CNC machining machine tool that uses continuously moving fine metal wire as an electrode to pulse spark discharge on the workpiece to generate a high temperature of over 6000 degrees, ablate metal and cut into a workpiece. The principle of wire processing is the phenomenon that there is a gap between the wire electrode and the workpiece, and the metal is removed by continuous discharge. Since the slow-moving wire cutting machine adopts the method of wire electrode continuous feeding, that is, the wire electrode is processed during the movement, so even if the wire electrode is worn out, it can be continuously supplemented, so it can improve the machining accuracy of the parts and slow the wire. The surface roughness of the workpiece processed by the cutting machine can usually reach Ra=0.8μm and above, and the roundness error, linear error and dimensional error of the slow-moving wire cutting machine are much bett...
The Purpose Standardize the management of the scrapping of the company's metal stamping dies, prevent the loss of company assets, and formulate this system specially. Scope of application It is suitable for the management of the company's scrap molds. Definition If the molds listed in the assets of the company fall under one of the following circumstances, the use management department may apply for scrapping. 1. Molds that exceed the specified service life. 2. The mold is severely damaged by accidents or accidents, and molds that cannot be repaired or have no repair value. 3. Metal stamping dies that have not reached the service life, but due to safety, quality, efficiency and other issues, the repair still fails to meet the minimum requirements of the customer's product process or affects the production safety and efficiency. 4. Product customers have stopped placing orders or have not placed orders for molds in several years. 4. Responsibilities 1. Responsibilities of th...
KOVAR parts are commonly used as metal casing materials in the electronic packaging industry. Because they have a linear expansion coefficient close to that of molybdenum group glass, and can produce less sealing stress during the sealing (melting) process with molybdenum group glass, so To obtain good air-tightness, in order to make the metal tube and shell to achieve air-tight sealing, in the entire sealing process, the annealing process undoubtedly plays an important role as a link between the previous and the next. The internal stress generated during KOVAR machining also prepares the material structure for the implementation of the subsequent process-the sealing process of the metal parts. The main purpose of annealing Kovar shell before sealing is to: (1) Eliminate machining stress. When Kovar undergoes plastic machining deformation during cold working, about 10% to 15% of the applied energy is converted into internal energy, which is commonly referred to as internal stre...
Common welding methods for titanium and titanium alloys are as follows: Argon arc welding, submerged arc welding, vacuum electron beam welding, etc.
Tungsten argon arc welding is used for thicknesses of 3 mm or less, and argon arc welding is done for 3 mm or more. The purity of argon is over 99.99%, and the content of air and water vapor in argon is strictly controlled.
Currently, for TC4 titanium alloys, argon arc welding, plasma arc welding are often used for welding, but both methods need to be filled with welding material.
Limitations on shield gas, purity and effectiveness increase the oxygen content of the joint, reduce its strength and increase its post-weld deformation.
Electron beam welding and laser beam welding are used. The following is a description of precision welding and precautions for TC4 titanium alloy.
1. Weld hole problem
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Weld pores are the most common defect in welded titanium alloys, and the main causes of pores are hydrogen and oxygen present in the arc region of the metal to be welded. In electron beam welding of TC4 titanium alloy, there are almost no vent defects in the weld. To this end, the study focuses on process factors for the formation of pores in laser welds. Test results show that weld pores are closely related to the energy of the weld line during laser welding. If the weld line has moderate energy, there are very few or even no pores in the weld. If the line energy is too high or too low, it will cause serious pore defects in the weld. In addition, the presence of poor porosity in the weld is also related to the wall thickness of the weld. Comparing the test results of the samples, we can see that as the wall thickness of the weld increases, the probability of pores in the weld increases.
2, internal quality of welded part
Sample of titanium plate butt welding by electron beam welding and laser welding. Examine the internal quality of the weld. After testing, the internal quality of the weld has X-ray defects up to GB3233-87 Level II requirements. There are no cracks on the surface and inside of the weld, the appearance of the weld is well formed and the color is normal.
3. Weld depth and its variation
Titanium alloys are used as engineering components with specific requirements for weld depth. Otherwise, the component strength requirements cannot be met.
In addition, in order to realize precision welding, it is necessary to control fluctuations in welding depth. For this reason, two sets of butt test rings were welded by electron beam welding and laser welding, respectively. After welding, the test ring was analyzed in the vertical and horizontal directions to examine the variation in weld depth and weld depth. The results show that the average welding depth of electron beam welding reaches 2.70 mm or more. The range of variation in welding depth is -5.2 to + 6.0% and does not exceed ± 10%. The average welding depth of laser welding is about 2.70mm, and the welding depth varies from -3.8 to + 5.9% and does not exceed ± 10%.
4, joint deformation analysis
Butt test rings are used to inspect weld deformations at joints and detect radial and axial deformations of the butch test rings. The results show that the deformation of electron beam welding and laser welding is very small. Radial shrinkage deformation of electron beam welding is f 0.05 to f 0.09 mm, and axial shrinkage is 0.06 to 0.14 mm. The radial shrinkage deformation of laser welding is f 0.03 to f 0.10 mm, and the axial shrinkage deformation is 0.02 to 0.03 mm.
5, Titanium welding seam analysis
After chemical detection, the weld structure is a + b and the fine structure is columnar crystal + equiaxed crystal. A small amount of rasmartensite appears, the particle size is close to the matrix, the heat-affected zone is narrow, and the morphology and properties are ideal. After investigation, we can conclude that: For TC4 titanium alloys, whether laser welding or electron beam welding, the internal quality of the weld is a national standard as long as the process parameters are properly matched. GB3233-87II Welding requirements can be met. Achieves precision welding of TC4 titanium alloy. The appearance of the weld is well-formed and the color is normal. The welding height is low, and defects such as undercuts, dents, and surface cracks do not occur.
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