Causes of mould damage during die-casting process

 

　　1, the die temperature

　　Mould should be preheated to a certain temperature before production, or chilling when high temperature liquid metal filling, which resulted in increased mold temperature gradient layers, zinc die casting thermal stress forming, make the mould surface cracks, even cracking.

　　During the process of production, the die temperature increases continuously, and when the mold temperature is overheating, it is easy to produce adhesion mode, die casting machine and the motion parts fail to cause the surface damage of the mould.

　　The cooling temperature control system should be set up to keep the mold working temperature within a certain range.

　　2, the filling

　　With high pressure and high speed, the metal liquid will have a severe impact and erosion on the mold, resulting in mechanical stress and thermal stress. During the impact process, Multi slider die casting machine the metal fluid, impurities, gas and the surface of the mold can produce complex chemical action, and accelerate corrosion and crack production. When the liquid metal is gas, low pressure area in the cavity expansion first, when the gas pressure, blasting introversion, Die casting pull out the metal particles on the surface of the cavity and damage, the crack due to cavitation.

　　3, open mould

　　In the process of core and mold opening, mechanical stress can be generated when certain components have deformation.

　　4. Production process

　　In each of the die casting process, due to the mold with liquid metal, the heat exchange between the mould surface temperature changes periodically, cause periodic thermal expansion and contraction, produce periodic thermal stress. If the surface of the die is stressed by heating during casting, the mould surface will be tensile stress due to cooling. When this kind of alternating stress is repeated, the internal accumulation of the mould becomes more and more large. When the stress exceeds the fatigue limit of the material, the surface of the mould cracks.

In the process of processing and processing, the causes of die failure in die casting are made

 

　　In die-casting production, the most common form of mould damage is cracking and cracking. Stress is the main cause of mould damage. Thermal, mechanical, Die casting chemical and operational shocks are all sources of stress, including mechanical stress and thermal stress. Stress is generated by:

　　(1). In the process of tooling and manufacturing

　　1. Quality of blank forging

　　Some moulds produce only a few hundred pieces and crack, and cracks develop quickly. Is probably the only when forging to ensure the appearance size, Multi slider die casting machine and the dendritic crystals and inclusions in the steel carbide and loose defects such as shrinkage cavity, bubble along the processing method is lengthen, forming streamline, die casting machine the streamline of after the last of the quenching distortion and cracking in the process of using, embrittlement, failure has enormous influence on the tendency.

　　2. The shear stress generated during the final processing of cars, milling and planing can be eliminated by annealing in the middle.

　　3. During the grinding of hardened steel, zinc die casting the grinding stress is produced, resulting in frictional heat during grinding, resulting in a softening layer and decarburization layer, which reduces the thermal fatigue strength and can easily lead to thermal cracking and early cracks. Of h13 steel after fine grinding, can be heated to 510-510 ℃, to one hour per 25 mm insulation thickness for eliminating stress annealing.

　　4. Electric spark processing produces stress. The surface of the mould produces a layer of enriched electrode elements and dielectric elements, which are hard and brittle. The layer itself has cracks and stresses. When the electric spark is processed, the high frequency should be used to minimize the white light layer. The polishing method must be removed and tempered. The tempering is carried out at the three level tempering temperature.

　　(2) in the process of mould processing

　　Heat treatment undeserved, can cause mold cracking prematurely discarded, especially by conditioning only, not for quenching, surface nitriding process again, can appear in die casting for thousands of times after surface crack and craze.

　　Is generated when the steel quenching stress, thermal stress of cooling process with phase transformation of the organization result of stress superposition, quenching stress was the cause of shape, craze, solid temper must be carried out to eliminate stress.

The extruding properties of several kinds of rubber

 

　　The extruding process is used to press out the cylinder wall and the screw part of the machine, so that the glue can be extruded and preliminarily designed, and the extrusion process also becomes the extrusion process.

　　The main equipment of extruding process is extruder.

　　The extruding properties of several kinds of rubber: the pressure of natural rubber is fast and the shrinkage of semi-finished product is small. Body temperature of 50-60 ℃, Rubber Parts starting from 70-80 ℃, mouth 80-90 ℃; Styrene-butadiene rubber pressure out of the slow, shrinkage deformation, surface roughness, the body temperature of 50-70 ℃, the nose temperature 70-80 ℃, the mouth temperature 100-105 ℃; Neoprene delivery without sufficient heat, body temperature 50 ℃, ℃ the nose, Custom Mold Rubber Parts mouth type 70 ℃; Ethylene propylene rubber extrusion speed, small shrinkage rate, body temperature of 60-70 ℃, the nose temperature 80-130 ℃, Rubber Seal mouth, 90-140 ℃. The butyronitrile rubber has poor performance and should be fully heated when pressed. Body temperature of 50-60 ℃, the nose temperature 70-80 ℃.

The compressional properties of several common rubber

 

　　The natural rubber heat shaping is large, the shrinkage rate is small, the pressure is easy, easy to adhere to the hot roller, should control each roll temperature difference, so that the film can transfer smoothly; Styrene butadiene rubber has a small thermal plasticity, and the shrinkage rate is large, Rubber O-Ring so the rubber that is used for pressing is to be fully plasticized.

　　Due to the obvious effect of styrene butadiene rubber, the temperature of the rolling temperature should be lower than that of natural rubber. Neoprene in 75-95 ℃ is easy sticky roller, Rubber Gasket difficult to rolling, should be used at low temperature or high temperature, rolling to rapidly cooling, mixed with paraffin wax, stearic acid, can reduce the sticking phenomenon; It can be operated continuously in a wide range of temperature, with a large shrinkage of the rubber material when the temperature is too low. Small NBR thermoplastic property, shrinkage, the kind of adding filler or rubber softener can reduce shrinkage rate, when the filler weight accounted for more than 50% by weight of the raw rubber, Rubber Seal can obtain the smooth surface film, nitrile rubber viscosity a little cold roll.

　　Before rolling, need to pre processing of rubber and fabric, prior to entering rubber calender, the need to put on a thermal refining machine before it turns, Custom Mold Rubber Parts the technology for cooking or preheat, the purpose is to improve the rubber mixing uniformity, Rubber Parts and further increase the plasticity, raise the temperature, increase the plasticity. In order to improve the adhesion of rubber and the fabric performance, ensure the quality of calender, the need for fabric drying, moisture content control in 1-2%, moisture content is low, fabric harden and calender easy damage, high water content, poor adhesion.

The digital signage market offers new business opportunities for satellite operators

 

　　If the phone is the "fourth screen" of information, digital signage is the "fifth screen". Digital signage is being touted as a major emerging advertising market, IP66 and it is also providing new market opportunities for satellite operators.

　　Digital signs have centrally controlled displays designed to deliver information such as notifications, entertainment, merchandising and advertising to target groups. Although digital signage is similar to a TV device in a bar, it is not a traditional broadcast model. Digital signage is designed specifically for display screens and audiences, touch screen monitor which can be installed anywhere. Moreover, thanks to the decline in the price of LCD screens, the popularity of broadband and the demand for new advertising revenue, there are many factors.

　　Dispersed market

　　For now, digital signage marketing is not easy. At first, sunlight readable advertisers in their annual media budgets are not sure whether digital signs count as "online media advertising" or "offline media advertising." Meanwhile, panel PC the market for digital signs is so fragmented that it is hard to give customers a clear answer. As a result, the current hype about the attractive digital advertising opportunities available to digital signage has been overblown.

　　However, digital signage also has many obvious advantages, especially in the case of the display, which can connect directly with consumers via SMS and bluetooth. Digital signage operators claim that digital signage is lower than other forms of media each time it is associated with a user's fee (CPM). The NSR says that CPM will be lower as the number of digital signage displays to a certain number.

　　Another key advantage of digital signage, All in one computer which is also particularly attractive to satellite operators, is the cost of running a digital signage network. Recently from the NSR a survey report on digital signage, for the cost of running a digital signage network has carried on the simple calculation, the cost including CPE (display, media player, connected devices and the AV cable) cost, high speed Internet laid (server and the formation of high speed network software) cost, installation cost, and the overhead cost of each year, such as network bandwidth cost and maintenance cost, etc.

　　Of course, the final actual cost is also related to the number of screens and places to place them. If each screen can be calculated by the average life span of more than 10 years, the deployment of each screen cost between $2300 and $3200 - that is, if the average site deployment of 3 ~ 4 screens, so the cost of each site for $7000 to $10000.

　　In terms of connection cost, NSR compares two different transmission modes. They are two - way terrestrial transport (two-way) and dvb-s2 (dvb-s2) and land-to-earth transmission. The NSR found that if there were more than 4,500 screens in the network, the cost of satellite transmission per display would be lower than that of the ground, and the more screens, the lower the cost.