Forging die refers to a tool that can form blanks into die forgings. Forging die is the key process equipment necessary in the production of die forgings, and is a tool that needs to be used in every stroke of the equipment. It plays a pivotal role in the production of die forgings.
The forging die is a die used in the forging process. The raw material is plastically deformed in the forging die under the action of external force to obtain parts of the required shape and size. Forging dies can be divided into hot forging dies, warm forging dies and cold forging dies according to different forging temperatures. Hot forging dies can be divided into hammer forging dies, screw press forging dies, mechanical press forging dies, flat forging dies and hydraulic forging dies due to different equipment. In the press forging, it is necessary to design and process the die set. During the forging process, the blank (such as roll forging, cross wedge rolling) die, trimming die, punching die, correction die, cold precision pressing die, etc. are also required. Moulds and devices also belong to the category of forging moulds.
The main technical development direction of forging dies is to improve the level of die design, adopt new die materials, and use high-efficiency and high-precision processing methods to achieve high precision for forgings under the condition of long life of the die.
With the improvement of the overall level of my country’s manufacturing industry, my country’s forging die technology will reach the international advanced level, and some innovative and unique technologies will reach the international leading level.
The Features Of Forging Die
Forging die is an important equipment to realize die forging process, and it is a branch with a long history in the die category. Due to the complexity of the forging forming process, the corresponding forging die has the following technical characteristics:
- Multi-step forming and complex structure. Metal forging forming belongs to volume forming, which is difficult to achieve one-step forming and requires multiple deformations. The forming steps of complex forgings can reach as many as 12 steps. Therefore, a set of forging dies is often composed of 10 or more dies.
- High temperature, heavy load and harsh working conditions. The metal forming temperature is 450°C (non-ferrous metals) to 1 300°C (iron and steel materials), and the surface temperature of the mold cavity can reach 300°C to 750°C. At the same time, the external force required for metal deformation is also provided by the press through the die, and the die used for forging of steel materials can bear a load of 500 (hot forging) to 2 000 MPa (cold forging).
- Due to the flow of the metal blank when deformed under high temperature and high pressure, the forging mold cavity needs to maintain the integrity of the working surface of the cavity in addition to the normal parting surface, and the mosaic structure cannot be adopted.
The technical characteristics of the forging die determine the design of the forging die. It strongly relies on the design of the forming process. It is necessary to select the die material and carry out reasonable heat treatment, and use advanced processing technology to ensure the accuracy and surface quality of the die cavity.
The design of forging die should follow the three principles of good use performance, excellent processing performance and certain economic performance. At the same time, it is necessary to be familiar with the process characteristics of metal during forging, master the basic structure and working performance of various forging equipment, and design molds with good formability, reasonable service life, and easy installation, debugging and maintenance based on actual conditions.
To achieve the above goals, usually should be considered in the forging die design:
- ①The batch of forgings. For forgings produced in small batches, use molds with simple structures as much as possible, and the life of the molds can also be designed to be lower; for forgings produced in medium and large batches, the mold structure should use multi-step molds with billet making, pre-forging and final forging. The mold materials Reasonable cooperation is required to ensure that the entire mold has a long life.
- ②The material of the forging. Determine the forming step and deformation rate according to the deformation ability of the material to ensure the quality of the forging after the final forging.
- ③The shape of the forging. Forgings with complex shapes must adopt a method of dispersing deformation of multiple cavities to reduce die load, reduce press tonnage, and avoid forging defects.
- ④Forging equipment. The main consideration is the forging hammer, and various presses, the structure of the die and the die material must be different.
The Wear Of Forging Die
Wear mainly refers to the relative movement between the two parts in the friction pair. The geometric, physical and chemical properties of the friction surface of the forging die and its wear pattern and type are basically similar to the wear of ordinary mechanical parts. The wear mechanism of the die is also developed on the basis of inheriting the mechanical wear mechanism and based on the characteristics of the working conditions of the forging die. In addition to observing the general law of wear of mechanical parts, the wear of forging dies also has its particularity due to its harsh working environment.
The wear in the forging process includes the wear of the forging die and the wear of the workpiece. In fact, mold wear is a special case of many mechanical parts wear. Under normal circumstances, mold wear follows the general law of mechanical parts wear. However, due to the special working conditions of molds, especially hot forging dies, their wear also has its particularity. . Therefore, when studying mold wear, it is necessary to understand the wear mode and type, and then conduct research based on the tribological characteristics of high temperature, high pressure (load) and high frequency (pulse) of metal forging.
There are many types of plastic processing dies, such as stamping dies, punching dies, blanking dies, shearing dies, cold and hot extrusion dies, precision pressing dies, punching dies, cold forging and hot forging dies, correction dies and so on. These dies have their own characteristics, and the working conditions of hot forging dies are the most complicated.