worm shaft manufacturers

The preheating temperature and interlayer temperature during welding are not controlled. Reasons: (3) Too many surfacing layers, improper selection of welding materials. Countermeasure: Pay attention to grasp the preheating temperature (the preheating temperature is mainly related to the carbon content of the base material) and the temperature control of the interlayer during welding.

Some welding material structures are directly high-hardness martensitic structures, and some welding materials can only be transformed from austenite structures to high-hardness martensitic structures when overlaying more than three layers.

Countermeasures: Use small current and short arc welding as much as possible, and the amplitude of the electrode swing during welding is not greater than 1..Reasons: (1) The current is too large during welding, the dilution rate of the mold base metal is too large, and the alloy elements of the mold base metal are damaged.5 times the diameter of the  copper worm gear electrode. Countermeasure: Select welding materials suitable for the number of surfacing layers

Lost foam casting is referred to as EPC, also known as gasification casting or solid casting. It uses the foam plastic pattern instead of the ordinary compact pattern. After the mold is made, the pattern is not taken out and poured directly into the metal liquid. Under the action of the high temperature metal liquid, the foam plastic pattern is heated and vaporized and burned to disappear, and the metal liquid replaces The space position occupied by the original foam plastic pattern is cooled and solidified to obtain the desired casting. Simplified drawing of lost foam casting process: The process flow of lost foam casting production line is divided into two parts: white area and black area. First, the white area process flow: First select the original beads suitable for it according to the material and wall thickness of the casting.

The original beads are added into the batch pre-fabrication machine for pre-expansion in a fixed amount, so as to achieve the density required by the process, and dried by the vulcanization bed of the pre-fabrication machine, and then sent to the curing chamber for curing. The matured beads are transported to the molding room, and the beads are injected into the mold on the molding machine, which is expanded and melted by steam to form a casting pattern, which is cooled and cooled by cold water to make the white mold have the same strength. The white mold is manually taken out of the machine and placed on the white mold drying truck, and then transported to the hot air tunnel drying room for drying. The white mold drying car walks on the drying room track, and every time a car is pushed into the room, a car is ejected from the other end, and the cycle is repeated. The drying room adopts a hot air forced circulation Self-lubricating industrial brass bushing system. The temperature and humidity in the drying room are automatically controlled by PLC to meet the process requirements, which greatly improves the production efficiency and saves energy. After the white mold is dried, it is transported to the group mold for assembly and bonding and pouring the riser. The assembled white mold is transported to a paint dipping room. The castings of different materials are selected with different paint formulas. The raw materials are put into the paint mixer for mixing. After the time required by the process is reached, the paint density is tested, and then the test is passed. The paint tank is for workers. Put the dipped white mold on the drying truck and transport it to the primary drying room of the yellow mold for drying. The dried yellow mold is transported to the secondary coating room for secondary dipping coating to meet the coating requirements of the process. Thickness, and then transported to the secondary drying room of the yellow mold for drying and repairing. After the second drying, the yellow mold is transported to the black area molding department with a drying truck for box filling and modeling, and the empty truck returns to the molding room.

At this point, the white area process is all over. Second, the black area process flow: 1. The molding department: the molding department consists of two molding lines and a return line. The circulation of the sand box is completed by the sand box track and the manual track changing vehicle. Each production line is made of The number of sand boxes required by the process. Each molding line is composed of a 2-ton single-dimensional vibration table and two 4-ton frequency conversion three-dimensional vibration tables. The finished sand box enters two pouring cooling lines in turn, and the pouring cooling line consists of a vacuum docking machine. After the pouring cooling line enters a certain number of sand boxes, the vacuum docking machine is automatically docked and manually poured. After the pouring is completed, the pressure is maintained and cooled. After the pressure is maintained, the vacuum docking machine is reset and the vacuum is removed. After the pressure is maintained, it enters the cooling section for cooling. Simultaneously with the pouring of these two pouring lines, the sand box with the moulding line made in order enters the two casting lines to wait for pouring, and repeats the actions of the first two casting lines, so as to cycle. This modeling department adopts BSZ-04k frequency conversion three-dimensional vibration table, its structure and working principle: This machine uses three pairs of 6 excitation motors as excitation sources. Each pair of vibration motors run in reverse synchronously to form a combined force in three directions (X, Y, Z), so that the vibration table and the sand box above it vibrate with a certain acceleration to complete the tightening of the dry sand in the sand box real. The vibration table is supported by air springs, which can be raised and lowered to make the sand box more stable during the vibration process and prevent the sand from squeezing the white mold. In addition, the vibration table is also equipped with a pneumatic automatic clamping device. It realizes the fast, convenient and flexible operation of the sand box and the vibration table. 2. Vacuum negative pressure system: The vacuum system is the main equipment of the lost foam casting process. Its role is to create a stable negative pressure field for the negative pressure sand box, so that the dry sand reaches a certain degree of compactness under the action of atmospheric pressure. Absorb gas and dust particles generated in the foam model gasification process to ensure smooth and orderly pouring. This set of vacuum system is composed of two 2BE water ring vacuum pumps, dust filter, pressure stabilizing tank, water tank, and vacuum docking machine. 2BE water ring vacuum pump is domestically produced with German technology, with stable performance, high efficiency and energy saving. The working process of the machine is that the waste gas in the sand box is firstly pumped to the wet dust collector, and the purified waste gas filtered by the dust collector enters the voltage stabilizing tank (the voltage stabilizing tank plays a role of stabilizing the negative pressure to prevent the negative pressure value The excessive fluctuation of the negative impact on the negative pressure value of the sand box), the regulator tank is connected with the water ring vacuum pump, the exhaust gas is drawn into the vacuum pump from the regulator tank and then sent to the gas-water separator, and the exhaust gas after the gas-water separation is It is discharged into the atmosphere, and the separated water is recycled. The hydraulic box turning machine of the system can realize the automatic sand dropping function of the sand box and reduce the labor intensity of the workers. 3. Sand processing system: The casted and cooled castings are transported to the return line along with the sand box by manual track changer.

There are two types of chemical methods. The mechanical method is to use various mixers such as ball mill, V-shaped, conical and spiral mixers to mechanically mix each component powder evenly without chemical reaction. Mechanical mixing is divided  into dry mixing and wet mixing. The former is dry mixing in gaseous medium. The latter is wet mixing in liquid medium. The requirements for wet mixed media are that they do not react with the mixture, have low boiling point, are volatile, non-toxic, have wide sources, and have low cost. Commonly used wet mixed media include alcohol, gasoline, acetone, water, etc. The addition amount of wet mixed medium should be appropriate. If it is too much, the slurry volume will increase, the powder amount between balls will decrease, and the mixing efficiency will decrease. Too little will increase the viscosity of the slurry, make the ball difficult to move and reduce the mixing efficiency. When mixing with a ball mill, the mixing and grinding processes can be combined.

At this time, relatively strong mixing is adopted to further crush the particles at the same time. This has been widely used in the production of hard alloy and structural materials. Chemical mixing is to uniformly mix metal or compound powder with salt solution added with metal; Or all the components are mixed in the form of a certain salt solution, and then treated by precipitation, drying, reduction and the like to obtain a uniform mixture. Its uniformity is better than that of mechanical method, which is more conducive to alloying and homogenization during sintering. The obtained product has ideal microstructure and excellent properties. (4) granulation. The process of making small particle powder into large particle powder or bronze bushing Manufacturers pellet. It is commonly used to improve the fluidity of powder and stabilize the loose density of powder to facilitate automatic pressing. There are many methods of granulation. Take cemented carbide powder as an example, there are compact method, rolling method and spray drying method.

Granulation method. The agglomeration method is to press the powder material into agglomerates under low pressure, mash and sieve the agglomerates to obtain pellets. This method is complicated, with low productivity, hard particles, poor sphericity, poor fluidity and difficult process control. The rolling method is to send the mixture added with appropriate amount of alcohol or acetone into an inclined circular container rotating at a low speed, and obtain the granular mixture after rolling for a certain period of time. The spherical ratio of the obtained aggregates is higher than that of the pressure agglomeration method, the particle size is more uniform, and the process is simpler. Spray drying is an advanced process for granulation while drying slurry. The method comprises the following steps of: adding paraffin-alcohol solution or paraffin-acetone solution into powder and stirring to form a uniform slurry containing 75% ~ 80% powder. The slurry is transported to an atomizing tower with nitrogen for spraying. The slurry is atomized into spherical slurry droplets under the surface tension of alcohol or acetone. They meet with hot nitrogen and dry into fine spherical or pear-shaped pellets, which are collected at the bottom of the tower. Spray drying granulation has the following advantages: soft particles, uniform particle size, high sphericity and good fluidity; The particle size, loose density and dry and wet degree of the particles are easy to control. The drying and granulation time is short and the dirtiness is less. Continuous production is easy to realize automation. Therefore, although the equipment cost of this method is relatively high, the total cost is low and it is an economical granulation method. Major cemented carbide manufacturers in various countries have adopted spray drying granulation to produce cemented carbide mixtures. Powder granulation is also applied to the preparation of forming materials for ceramics, Mn-Zn ferrite and other powders. Preparation of powder: It mainly depends on the performance of the material and the cost of the preparation method. Powders are formed by transferring energy to the material,

Avoid direct contact between furnace gas and aluminum alloy liquid, try to keep the oxide film intact during smelting, avoid unnecessary stirring covering agent stored in the dryer, and keep it above the temperature before use. In the design of metal molds, adequate exhaust structure should be given, the gate system should be reasonably designed to avoid being involved in the gas, and the jitter plugs should be appropriately added to the areas where pinholes are likely to be generated. The mold must still be preheated and warmed to fit the mold. Controlling the gettering ability of liquid aluminum alloy The gettering ability of liquid aluminum alloy is mainly related to the chemical composition modification temperature and melting time of the alloy. The chemical composition of the door aluminum alloy is analyzed from the following aspects: First, as the content of silicon increases, the fluidity of the alloy increases accordingly, and the tendency of the metal to shrink and thermally crack is reduced, but the aluminum alloy liquid reduces the solubility of hydrogen during solidification, and the precipitation of a large amount of magnesium hydrogen can strengthen the aluminum alloy.

The mechanical properties of aluminum and aluminum can refine the structure of the alloy and improve the mechanical properties. However, the gettering capacity of aluminum alloys is also related to these elements. The effects of commonly used elements on the hydrogen content in aluminum are shown in the table. Calculate the selected charge according to the chemical composition and the burning of the relevant elements, and reasonably configure the charge to ensure that the chemical composition of the aluminum alloy after melting is qualified, and the harmful substances are within the allowed range, so as to control the aluminum alloy's air-absorbing capacity . The increase and decrease of hydrogen in the aluminum alloy have no effect and increase its structure and properties. But the modifying agent exacerbates the tendency of the alloy to get inhaled. When the silicon in the aluminum alloy solidifies, it promotes the decrease of the solubility of hydrogen in the aluminum alloy. At the same time, it increases the viscosity and surface tension of the aluminum alloy, so that a large amount of Hydrogen does not run out of the casting and does not form pinholes. Therefore, the dosage of the modifier should be reasonable, and the specific dosage should refer to the instructions of the manufacturer of the modifier. For example, if the salt modifier is used, the amount of the modifier is the alloy amount. The temperature is within the normal melting temperature range. The higher the temperature, The greater the solubility of hydrogen. Therefore, under the condition that the aluminum alloy liquid has sufficient filling capacity, the lower temperature should be taken as far as possible. After the degassing refining and modification treatment of the alloy liquid, the interval from the furnace to the pouring should be as short as possible, and the pouring can be completed as soon as possible within the time allowed by the process specification. The increase of the cooling speed of the mold of the mold will cause the gas to dissolve in the casting in a supersaturated manner without precipitation, and avoid pinholes. The wall thickness of the mold of the mold is the main factor that determines the cooling rate of the casting.

The wall thickness of the metal mold used can refer to the reference value of the metal mold for the wall thickness decay. Coating coating Coating on the metal mold can not only increase the service life of the mold, control the solidification speed of the casting, obtain the required metallographic structure, but also avoid direct contact with the air, reducing the tendency of the metal mold to get air. The thickness of the coating is usually shown in the table where pinholes are prone to occur, and the corresponding mold coating should be appropriately thinned. In the pouring operation, the opportunity for the oxidation and gettering of the aluminum alloy liquid should be avoided. For this reason, after drying and coating the coating spoon, it is best to heat it to red, and then pick up the alloy liquid, so as not to lower the temperature of the alloy liquid. The pouring spoon only removes the slag before pouring. The distance between the pouring spoon mouth and the metal-type external gate should be as short as possible, keep the external gate always in a full state, prevent jitter and interruption, and strive to avoid turning the spoon as much as possible during the pouring process. Back to increase vortex. Degassing treatment of aluminum alloy liquids At present, aluminum alloy wheel manufacturers generally degassing aluminum alloy liquids, usually adding a three-gas refining agent and then refining and degassing by the nitrogen pass method. Three gas refining agents generate three main gases, namely the following reactions with the aluminum alloy liquid. At the melting temperature, and as a gaseous substance, when it floats upward, it adsorbs solid impurities such as oxide slag and floats to the liquid surface, effectively reducing the aluminum alloy liquid. Content of hydrogen. Principle of the nitrogen flow method When nitrogen floats upward from the bottom of the alloy liquid in the form of bubbles, due to the pressure difference of hydrogen at cast bushing Manufacturers the interface of the bubbles, the hydrogen in the alloy liquid continuously enters the bubbles. When the bubbles rise to the liquid level, the hydrogen It also escapes into the atmosphere, and during the rise of the bubble, it also adsorbs other solid impurities of the oxide slag and floats to the liquid surface together. Nitrogen must pass through a filtering device equipped with a desiccant before passing through the alloy liquid.

The desiccant can be discolored silica gel or calcium chloride. The desiccant should be replaced frequently. When the aluminum alloy liquid passes through nitrogen, it should be caused by the alloy liquid boiling motorcycle technology process material host Zhang He on the technical conditions of motorcycle piston ring discussion Tian Wen Sandian Kui Wuhan Auto Parts Factory since the 1990s The rapid development of China's motorcycle piston ring industry has broken the pattern of several designated enterprises, and has also produced a considerable number of people who do not have a deep understanding of the technical conditions and performance of piston rings, but have made exaggerations in pursuit of sales benefits. Publicity and hype caused confusion in the judgment and testing of the quality of process technology products.