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Types and characteristics of forging

Date锛2013-10-28 9:47:19

When the temperature exceeds 300-400 ℃ ( steel blue brittle region ) , to 700-800 ℃ , the deformation resistance of the sharp decrease , deformation energy has also been greatly improved. According to the different temperature regions of the forging , forging quality and forging process for different requirements , can be divided into forging, warm forging , forging three molding temperature zones. This temperature zone division of the original is no strict boundaries, generally speaking, in a recrystallization temperature region is called forging , hot forging, at room temperature without heating called cold forging .
Forging at a low temperature , the forging of the size changes little . In forging below 700 ℃ , less oxide formation , and surface decarburization phenomenon . Therefore, if the deformation energy in the forming energy range, forging easy to get a good dimensional accuracy and surface finish. As long as a good temperature control and lubrication cooling , 700 ℃ temperature below forging can also get good accuracy. Forging , due to deformation energy and deformation resistance are small, complex shapes can be forged large forgings . To obtain a high dimensional accuracy , the forging at temperature 900-1000 ℃ hot forging process . Also, pay attention to improving the working environment of forging . Forging die life ( forging 2-5 1000 1-2 ten thousand warm forging , cold forging 2-5 ten thousand ) and other temperature field is shorter compared to forging , but it's flexibility , low cost .
Blank when the cold deformation and work hardening , the forging die to withstand high loads , therefore , requires a high- strength forging die and to prevent wear and adhesion of the hard lubricant film processing method . In addition , in order to prevent the blank cracks , intermediate annealing when necessary to ensure the desired deformation. In order to maintain a good state of lubrication , the blank can be phosphated . In a bar and wire rod for continuous processing, the current cross-section can not be lubricated processing , is studying the possibility of using phosphate lubrication method .
According blank moves, forging can be divided into free forging , upsetting , extrusion, forging, closed die forging, closed upsetting . Closed die forging and closed upsetting because there is no flash, material utilization is high. With a process or several processes may perform complex forgings finishing. Since there is no flash, forging area to reduce the force , the required load is reduced. However, you should be careful not to make the dough completely restricted, this should strictly control the volume of the blank , control the relative position and the forging die forging measure , efforts to reduce die wear.
According to the movement pattern forging die forging can be divided into Orbital , put swaging , roll forging , wedge rolling, ring rolling and cross rolling , etc. . Orbital , swing rotary forging and ring rolling are also used precision forging . In order to improve the utilization of materials , roll forging and rolling horizontal elongated material can be used as a front -channel processing . Free forging and forging is the same as the local forming of rotation , it has the advantage compared to the size and forging , forging a smaller force can be achieved under conditions to form . Including free forging forging , including this way , processing material from the mold surface near the free surface expansion , it is difficult to ensure accuracy , so the direction of movement of the forging die and swaging process controlled by computer , you can use a lower forging force to obtain complex shapes and high precision products. Such as production varieties, large size turbine blades and other forgings.
Die forging equipment, freedom of movement and is inconsistent , according to the characteristics of the lower dead point deformation limit , forging equipment can be divided into the following four forms :
• Limit forging force : hydraulic direct drive hydraulic machine slider .
• quasi- stroke limit means : hydraulic drive crank hydraulic machine .
• Stroke Limit by: crank , connecting rods and wedge mechanism driving the slider mechanical presses .
• energy-restricted manner : the use of a helical screw mechanism and friction presses .
In order to obtain a high accuracy should be taken to avoid overloading the bottom dead point , control the speed and mold position . Because these will be on forging tolerances, shape accuracy and forging die life . In addition , in order to maintain accuracy , attention should also adjust the slider guide clearance , to ensure rigidity and lower dead point adjustment gear use subsidies and other measures .
In addition , according to the slider movement pattern and the vertical and horizontal movement of the slider ( for thin pieces of forging, cooling and lubrication of high-speed production of parts, forging ) method of the points , the use of compensation devices can increase the movement in other directions . The different ways, forging the necessary force , processes, material utilization , yield, dimensional tolerances and lubrication cooling are not the same , these factors also affect the level of automation factor.


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