The metal forming process of metal roller pressing machine
Ⅰ.Process method of metal roll press forming machine
The commonly used metal material forming process is the process method of producing parts and components，which is cold and hot forming. The common process is divided into the following categories: casting, forging, welding and cutting.
Pressure moulding(attention:pressure moulding is not equal to pressure casting) is a metal foundry technology,which is characterized by applying high pressure to the molten metal using the mold cavity.The moulds are usually made from stronger alloys.Pressure moulding is a process similar to injection molding.
Sand mold casting is to make molds out of sand.Sand mold casting involves placing a model of a finished part or a wooden model (a pattern) in sand, then filling the pattern with sand and taking the pattern out of the box to form a mold.
In order to remove the mold before casting the metal, the mold should be made into two or more parts;During the mold making process, holes and vents must be set aside to pour metal into the mold to synthesize the gating system.After the metal liquid is poured, the mold remains in place for an appropriate time until the metal solidifies.
Ⅱ. The moulds will be destroyed after the parts are taken out, so new moulds have to be made for each casting piece
Investment casting, also dewaxing casting, includes pressing wax, repairing wax, forming tree, dipping slurry, melting wax, casting metal liquid and post-treatment processes.Dewaxing casting is to make a wax mold of the part to be cast with wax, and then the wax mold is coated with mud, which is called a mud mold.After the clay mold is dried, it is roasted to form a pottery mold.Once roasted, all the wax molds melted and lost, leaving only the clay molds.Generally, when making mud mold, the pouring port is left, and then the metal melt is poured into the pouring port. After cooling, the required parts are made.
Die forging is a forging method to obtain forgings by making use of the die to form the blank on the special die forging equipment.According to different equipment, die forging is divided into hammer forging, crank press forging, flat forging, friction press forging and so on.Kun forging is a plastic forming process in which the material is plastic deformed under the action of a pair of reverse rotating dies to obtain the required forgings or forging blanks.It is a special form of form rolling (longitudinal rolling).
Forging is one of the two main components of forging (forging and stamping), which uses forging machinery to exert pressure on the metal billet to produce plastic deformation to obtain a certain mechanical properties, a certain shape and size of forgings.Forging can eliminate defects such as as-cast porosity produced in the smelting process and optimize the microstructure. At the same time, the mechanical properties of forgings are generally better than those of castings of the same material due to the preservation of a complete metal streamline.In the related machinery, the important parts with high load and severe working conditions (in addition to plate, profile or welding parts with simple shapes which can be rolled), forgings are more used.
Rolling, also calendering, is the process of forming an ingot of metal by passing it through a pair of rollers.If the temperature of the metal during calendering exceeds its recrystallization temperature, the process is called "hot rolling", otherwise it is called "cold rolling".Calendering is the most commonly used method in metal working.
The essence of pressure casting is to make liquid or semi-liquid metal fill the cavity of die casting mold (die casting mold) at a high speed under high pressure, and to form and solidify under pressure to obtain the casting method.
Low Pressure Casting——a process in which liquid metals are filled and solidified into castings under the action of a low pressure gas.Low-pressure casting was initially used for the production of aluminum alloy castings, and later expanded to produce copper castings, iron castings and steel castings with high melting points.
Centrifugal casting is a technology and method of injecting liquid metal into a high-speed rotating mold to fill the mold and form castings under the action of centrifugal force.According to the shape, size and production volume of the casting, the casting mold used in centrifugal casting can be selected as non-metallic mold (such as sand mold, shell mold or investment shell mold), metal mold or the mold with coating layer or resin sand layer inside the metal mold.
Lost form casting is a new casting method. Firstly,combines paraffin or foam models similar in size and shape with the casting into model clusters; secondly,brush the clusters with refractory coating and dry them; thirdly,bury them in the dry quartz sand for vibration molding; fourthly,cast them under negative pressure to gasifies; finally, the liquid metal occupies the position of the model and forms the casting after solidification and cooling.It is a new process of near-infinite and forming, which requires no mold taking, no parting surface and no sand core, so the casting has no flash, burr or die drawing slope, meanwhile,size error caused by core combination is reduced.
Squeeze casting,also liquid die forging, is to directly inject the molten metal or semi-solid alloy into open mold, then closed mold to produce filling flow, when it is formed into the required shape,high pressure is then applied to create a plastic deformation of the solidified metal (the shell),while the unsolidified metal is subjected to static pressure and high pressure solidification occurs at the same time, and finally the workpiece or blank is obtained.The above is direct squeeze casting.There are also indirect squeeze casting: inject the molten metal or semi-solid alloy into the closed mold cavity through the punch, leave it to crystallize and solidify under high pressure, and finally obtain the parts or blank.
