With the development of the automobile industry and China's accession to the WTO, the domestic and international markets are increasingly demanding on the quality and cost of automotive forgings, such as draft angles, weight tolerances, dimensions, and machining allowances. The price is not ideal, but the volume is large. In order to meet the needs of marketization, this article analyzed the process and repeated practice, found an ideal process, and has important significance for the production of similar products.
Product introduction and determination of process plan
Product introduction
The arm is a part used on the brake pump of heavy vehicles. The structure is shown in Figure 1. There are several difficulties in forging: (1) The draft angle is small, only 3° outside and 5° inside, while the top material ejection device is only one inside the 62 hole; (2) The machining allowance is small. Processing of 62 and square groove 23.2mm only use boring and broaching; (3) 10-pin 6.2*5 these 10 nails are difficult to fill and require a high degree of position, and the root fillet of the nail is R0.2. The wear of this part of the mold is faster, and it is easy to bump and deform during the production flow.
Determination of process plan
In order to adapt to mass production and improve efficiency, we have determined the following processes: (intermediate frequency furnace) heating / (wedge rolling) blank / (25000kN hot die forging press) bending / pre-forging / final forging / (3150kN double point pressure Machine) punching / trimming / normalizing / shot blasting / fine pressure. In the process flow, heating the billet is using two parts at a time, the shank of the part is slender, and the efficiency of the forging of the free-forging single billet is low. A wedge cross-rolling blank (as shown in Fig. 2) was used while cutting into two pieces on the rolling mill. Because the section of the part changes greatly, rolling from ∮55 to ∮23 requires two wedges to complete, so it is difficult to process and repair rolling dies.
The sizing process ensures the head and shank dimensions, and it is even more important to correct the position of the 10 nails, the rounding of the root, and the bending of the shank. Therefore, the use of two standard press plates with five holes for movement ensures the position of the nails and rounding of the roots, which improves the life of the forging dies.
Mold design and production of points
Normally, only the shape of the extruded billet is considered to be consistent with the forging when designing the press bending die. Due to the large difference between the thickness of the arm body and the shank, the stalk of the bend blank floats when it is placed in the pre-forging die. When the pre-forging is performed, the shank and the large-headed transition cause a fold. Due to the slewing of the curved blank, pre-forging When the metal flow in this area is too large. Therefore, the design of the bending blank must be such that the bending blank is placed on the pre-forging die such that its outer shape conforms to the shape of the pre-forging die.
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