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Keywords： PTW series-wet dust collector PTSF Series-Intelligent Through Type Sandblasting Machine Industrial Centrifugal Separator-N Series
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Sandblasting (shot) process:Sandblasting (shot) is a mechanical surface pretreatment method that uses the impact of high-speed sand flow to clean and roughen the surface of the substrate. Compressed air is used as the power to form a high-speed jet beam to spray abrasives (emery sand, iron sand, stainless steel sand or abrasives of various shapes and materials) on the surface of the workpiece at high speed, so that the outer surface shape of the workpiece surface is changed, and the surface of the workpiece is affected by the abrasive. The impact, cutting and grinding of the workpiece can obtain a certain degree of cleanliness and different roughness on the surface of the workpiece, increase the surface area of the workpiece, and improve the mechanical properties of the workpiece surface. At the same time, it also improves the fatigue resistance of the workpiece and increases the workpiece. The adhesion between the post-treatment coatings extends the durability of the coating film, and is also conducive to the leveling of the coating and the improvement of the decorative effect. Basic principles of mechanical surface pretreatment-sand blasting (shot) and shot blasting: ※Pressure-feeding, siphoning, and liquid blasting (pills) use compressed air as the main power to generate abrasive jets.※In shot blasting, the motor drives the blades to generate centrifugal power to generate abrasive beams. Purpose of sandblasting (shot) and shot blasting:1. Roughness on the surface of the workpiece: the surface of the workpiece will have different values of roughness Ra due to different abrasive grain sizes, and the surface area will increase. The value of Ra can be obtained by measuring with a roughness meter.2. Make the surface of the workpiece clean: remove impurities, rust, oil slick, oxide skin, burrs, etc. on the surface of the workpiece. The cleaning level is: $2 1-3 level to obtain the level value through the 1$08501-3 standard comparison picture.The above 2 process results roughness Ra cleanliness SaThe main service is for workpiece coating (spraying or electroplating, etc.), process requirements for pretreatment adhesion before gluing, or surface decoration requirements for workpieces.3. Shot peening: shot peening of crankshafts, aerospace gears, springs and other parts is a special cold processing process, which continuously impacts the surface of the metal material through the flow of projectiles and makes the surface (0. 1~0. 8mm) material Cyclic plastic deformation occurs, thereby forming a process of deformation strengthening. Through the cyclic plastic deformation of shot peening, the structure of the material is changed, the sub-grain is greatly refined, the dislocation density is increased, and the lattice distortion is increased; a high macroscopic stress is formed, and the surface roughness and surface morphology are also increased. Everything changes. Various changes in the surface of the material will significantly improve the fatigue and stress corrosion resistance of the material, and strengthen the surface performance of the material.Factors affecting the effect of the sandblasting process: 1. Abrasives: divided into metallic abrasives and non-metallic abrasives. Different particle sizes, shapes, materials, and hardness will produce different shapes of roughness and cutting force. Different roughness values and cleanliness values; 2, air pressure and flow: the greater the pressure and flow, the higher the blasting efficiency and the more uniform;3, the spray angle And distance: the best distance for suction jet is 150mm, the best distance for press-in jet is 300mm; the ideal angle is 45 degrees;4. Spray method: press-in/siphon/. With the same air consumption and nozzle diameter, the efficiency of the press-in type is about twice that of the suction type.Light Industrial ProductsHeavy industry products
Dimple size is very important! It will directly affect the shot peening strength and coverage. The peening strength is directly proportional to the size of the pits. The coverage rate increases with the size of the pit (when other conditions are the same). Therefore, the size of the pit is very important. The control of the pit size depends on the known (a) size, (b) the influencing factors of the size, and (c) the shot peening method that affects the pit size. Figure 1 The shape of the pit under low coverage rate A typical dimple is shown in Figure 1. The shape is approximately circular. A pit marked at A in the picture is "equivalent to a circle", as in the picture B is a circle with a diameter of d. When the coverage and pit depth are modeled, they can be assumed to be equivalent circles. This article is about the factors that affect the size of the pit Perform quantitative analysis. I hope that readers who do not like mathematics will not leave because of the introduction of these necessary equations. Common calculation programs, such as Excel, allow known values ??to be inserted into these equations. For example, when calculating the pit diameter in Excel, insert the known pellet diameter in A1, the known pit diameter in A2, and the equation in A3: =(A2-(A1^2-A2^2)^0.5 )/2. This equation is the same as equation (1) in the following article. Shot size and pit diameter The size of the shot material and the size of the pit caused by shot peening exist Linear relationship-other conditions are the same. Both actual observation and theoretical analysis can draw this definite conclusion. Standard shot peening will cause pits, the diameter of which is about 30-50% of the shot. Therefore, we can infer the size range of the pits-because we already know the diameter of the pellets used. As shown in Figure 2, when the diameter is In the case of the cast steel shot of D, the range of the estimated pit diameter d. SAE nominal shot size shows that this is the most common size parameter. It can be seen that a huge range of dimple diameters may be encountered. Assuming that d is 40% of D, the diameter of the pit is approximately the same as the SAE value of the shot material in the micron level. For example, the diameter of the pits produced by S110 pellets is approximately It is 110 microns, and S460 pellets usually produce pits with a diameter of about 460 microns-1 micron equals 1um.
Shot peening is a cold working process that may produce effective shape changes to the workpiece. Each type of cold working process introduces residual stresses during the forming of metal workpieces. The shape change has two factors: plastic deformation and elastic deformation. This is different from the hot working process, the residual stress will be eliminated in the self-annealing process, so there is only plastic deformation. The elastic deformation is due to the residual stress imposed on the workpiece during the cold working process. This factor makes the flat test piece bend. The plastic deformation hp and the elastic deformation he (residual stress) work together to produce the overall deformation h. Therefore, hp+he=h. Figure 1. The combined action of plastic deformation hp and elastic deformation he causes Almen test piece deformation Elasticity is not permanent, because it can be removed by stress relief. A common example is the Almen test piece after shot peening. When the stress is relieved, its bending will be reduced, and only plastic deformation will exist. Analyzing the deformation caused by shot peening is very complicated , Including the simultaneous action of plasticity and elasticity theory. The simplified method calls the two theories separately as shown in this article. The shape change of the workpiece is usually caused by shot blasting of. This deformation may be favorable, unfavorable, or too small to be ignored. Favorable shot peening deformation can be summarized as "shot peening" or "distortion correction", whereas unfavorable deformation can be summarized as "distortion". The most common shot peening deformation is the Almen test piece. One side of the test piece was shot peened, so that its shape changed from a flat rectangular shape to a double curved shape. This is a favorable deformation, because the arc height when the test piece bends induced by shot peening is a parameter required for testing the strength of shot peening. As we all know, the shape change can be characterized by two mutually perpendicular curves. Plastic theory predicts this change in shape. The elasticity theory predicts the magnitude of the induced bending of the beam. This shape change is like the shape change caused by the "equivalent bending moment". In fact: the introduction of bending by shot peening is equivalent to applying an external bending moment. This external bending moment is also equivalent to the bending moment introduced by shot peening.
Shot peening is a basic surface treatment process for metal parts. Shot peening is a process in which a stream of high-energy projectiles performs work on the surface of the part. The result of the work done by the projectile is to leave pits on the surface. As the shot blasting time increases, there are more and more pits and the coverage rate is getting bigger and bigger. Figure 1 illustrates the process of increasing coverage. With the extension of the shot peening time, the growth rate of the coverage rate decreased, following the "law of diminishing marginal utility." In engineering applications, an important practical requirement is to use a relatively economical time to meet the coverage requirements. As the coverage increases, a layer of residual compressive stress will be generated on the surface of the part. This residual compressive stress layer is the "magic skin" that can increase the service life of parts. Figure 1 Typical coverage/shot peening time curve The shot peening beam itself must have a specified intensity level, such as N254 (at a special shot peening time T, that is, saturated Time, the N-type Almen test piece is bent 0.254mm after shot peening), which is a parameter to quantify the strength of shot peening. However, there is currently no parameter that quantifies the ability of the shot peening beam to reach the target coverage. This article focuses on the following content: (1)The ability of pellets to do work; (2) The formation process of the pit; (3) The coverage evolution process; (4) Comparison of coverage rate and shot peening intensity. About measuring shot peening beam to reach target coverage The parameters of the capabilities will be described in some details.
Currently, two parameters are used to characterize the effect of shot peening: coverage and shot peening intensity. Coverage is a visual two-dimensional parameter, it is easy to define (the area of ??the pit is the percentage of the total area), and it can be tested directly. The shot peening strength is an invisible three-dimensional parameter, which is difficult to define and can only be tested indirectly. The indirect test method for shot peening strength is Almen test pieces are shot peened in different cycles (time, number of passes or speed), and then drawn by saturation curve. When one side of the Almen test piece is shot peened, it will be bent and deformed protruding to the surface to be sprayed, and the arc height h of the bending deformation can be tested by the Almen tester. Different shot peening time t obtains different arc height values, and the shot peening intensity curve (usually called "saturation curve") can be drawn. "Saturation intensity" is a special arc height value on the saturation curve, that is, when the time is doubled, the arc height value increases by 10%, as shown in Figure 1. Saturation intensity is used to quantify the difference between different saturation curves, and it has become an industry quantitative method used to measure the energy intensity of shot peening beams. 图1 喷丸强度曲〖线（“饱和曲线”） 每一个丸粒撞击所产生的凹痕均会在平行于试片表面方向上产〗生一定的塑性ω 延伸变形。该塑性延伸变⊙形可以导致阿尔门试片发生δh的弯曲变形。该塑性变形是延伸变形←，因此阿尔门试片发生了凸向被喷面的弯曲变形。从这一方面来讲，对阿尔门试片的喷丸和喷丸成形非常相似。测具测试 每一个∮测试得到的弧高值h均是大量的个体的δh累计←而得到的，这和雨量▽器有相似的特征。图2显示了雨量器的测试方法。经过一段时▲间t的收集，雨水的高度为h，每一个雨滴对高度的贡献为δh。雨水的高度同样受Ψ到雨滴进入雨量器的速度的影响。因此ξ 可得以下公式： h=r.δh.t （1） 如果r和δh为已知常量，那么式（1）可以写成： h=a.t （2） 其中a是常数。（a= r.δh） 公式（2）是◇一个直线方程。直线方程可以通过测试不█同时间t的高度h而获得，如图2所示。该测试具有统计变化性，因此仅能作为已知公式≡的参考。在1805年，勒让德发明了“最小二乘〇法”，可以对现有数据进行最佳拟合，使①其符合现有的公式。到了计算机时代↙，工程师们厌倦了采用∏手动的方法对试验结果进行最」佳拟合。 图1 喷☆丸强度曲线（“饱和曲线”） 每一个丸粒撞击所产生的凹痕均会在平行于试片表面方向▲上产生一定的塑性延伸变形。该塑性延伸㊣变形可以导致阿尔门试片发生δh的弯曲变形。该塑性变形是延伸变形，因此阿尔门试片发生了凸向被喷面的弯曲变形。从这一方面来讲，对阿尔门试片的喷丸和喷丸成形非常相似。测具测试 每一个测试得到的弧高值h均是大量的个体的δh累计而得到的，这和▃雨量器有相似的特征。图2显示了雨量器的测试方法。经过一段时间t的收集，雨水的高度为h，每一个雨滴对高度的贡献为δh。雨水的高度同样受到雨滴进入雨量器的速度的影响。因此可得以下公式： h=r.δh.t （1） 如果r和δh为已知常量，那么式（1）可以写成： h=a.t （2） 其中a是常数。（a= r.δh） 公式（2）是一个直线方程。直线方程可以通过测试不同时间t的高度h而获得，如图2所示。该测试具有统计变化性，因此仅能作为已知公∩式的参考。在1805年，勒让德发明了“最小▅二乘法”，可以对现有数据进行最佳拟合，使其符合现有的公式。到了计算机时代，工程师们厌倦了采用手动的方法对试验结果进行最佳拟合。
Shot peening is a very important metal parts processing technology, which can effectively improve the fatigue life of the parts. The amount of information about shot blasting in today's society is very rich, but sometimes it may confuse people's sight, "One leaf is blind, but Taishan is not seen." This proverb means that if you pay too much attention to the details, you may not be able to grasp the general direction. This article mainly explains the content of Figure 1 in the form of six elements. 1. Parts, such as trailer leaf springs, when working Withstand the effect of cyclic load. 2. Cyclic load leads to corresponding cyclic stress. 3. If the stress is large enough and the cycle period is large enough , Cyclic stress can lead to fatigue failure. The stress of the part when the crack grows must be tensile stress. 4. Shot peening can effectively reduce fatigue failure Influence. 5. Shot peening introduces a layer on the surface of the part" "Miracle skin" has the effects of compressive stress and cold work hardening. The thickness of this "skin" depends on the peening strength. 6. The coverage is the effect of shot peening on the surface of the part One parameter. Coverage is the ratio of the area of ??the pit on the surface of the part to the surface area of ??the part. Whether the shot peening process is appropriate is determined by several factors, which can be determined from the figure Overview on 2.
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