Roll forging is the introduction of longitudinal rolling into the forging industry in recent decades and has been continuously developed to form a new forging process, which belongs to the category of rotary compression forming. The upper and lower two forging rolls of the roll forging machine are parallel and turn opposite. The roll forging die mounted on the forging roll rotates along the longitudinal direction of the blank by means of friction and continuously presses it locally, so that the cross-sectional area and height of the pressed part of the blank are reduced, the width is slightly increased, and the length is increased. The extension is larger. Therefore, roll forging is mostly used for forging process based on extension deformation, which has higher technical and economic superiority than die forging. Its characteristics are:
1. The required working load is small
The forming force required for locally pressing the blank is smaller than that of the die forging. Generally, a small-capacity roll forging machine is used, and then a smaller-capacity shaping device can be disposed.
2. High production efficiency
The productivity of multi-groove roll forging is generally comparable to that of die forging, while the productivity of single-roller one-roll forging is significantly improved, which is about 5 to 10 times that of die forging.
3. Less material consumption
The material utilization rate of the roll forgings is generally above 80%.
4. The intrinsic quality of the roll forgings is excellent
Good mechanical properties and high fatigue life.
5. Good working conditions
There is no impact during roll forging, vibration and noise are small, labor conditions are greatly improved, and mechanization and automation are easy to implement.
At home and abroad, we are extremely concerned about the application and development of the roll forging process. Roll forging can be forging forging, and forgings can be realized for some forgings in long shafts and sheets, and forging and forming. Therefore, in industrial applications, roll forging is often divided into two types: blank roll forging and forming roll forging. Depending on the degree of roll forging, the forming roll forging is divided into three types: final forming roll forging, initial forming roll forging and partial forming roll forging.
Forgings are forged in foreign countries, and only forgings with simple cross-section changes, such as ploughshares, hoes, steel forks, cross rafts, blades, etc., are produced by forming roll forging process. At present, a number of 10,000-ton mechanical forging presses have been built to produce large-scale automobile crankshafts and front axles. These automatic lines are equipped with roll forging machines to undertake the blanking process before die forging. On the special equipment of the blade cold roll forging machine, the production of cold-finishing roll for aero-engine turbine blades and compressor blades is realized.
In recent years, the roll forging process has developed rapidly in China. Automobiles, tools and other industries use the blank roll forging process and the mechanical forging press or friction press to produce various types of wrenches for connecting rods, crankshafts, front axles and random tools. For steel forks, cross sills, and automotive cross-section leaf springs with simple cross-section shapes, the use of final forming roll forging or partial forming roll forging (such as the boring and slabs of hoes is formed by roll forging and hot drawing respectively). of). Forgings with complex geometry and large thickness difference, such as forgings such as connecting rods, front axles and track joints, also have the process of initial forming roll forging, and then equipped with small-capacity die forging equipment for shaping. The first automatic line for connecting and rolling of the connecting rod designed and developed in China is the process of initial forming roll forging. The line was completed and put into production in 1981. Production shows that the line has low investment, high production efficiency, excellent forgings, and significant technical and economic benefits.