With the development of the automobile industry and China’s accession to the WTO, the domestic and international markets have become increasingly demanding on the quality and cost price of automobile forgings, such as draft angle, weight tolerance, size, machining allowance and other requirements are very high, and The price is not ideal, but the quantity is large. In order to meet the needs of marketization, this article analyzed the process and practiced it repeatedly, and found a relatively ideal process, which is of great significance to the production of similar products.
Product introduction and process plan determination
The arm body is a part used on the brake pump of a heavy-duty vehicle. 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 ejector ejection device has only one place in the ∮62 hole; (2) The machining allowance is small, ∮ The machining of 62 and square groove 23.2mm only uses boring and broaching; (3) 10-∮6.2*5 these 10 nails are full of difficulties and require high position, and the root fillet of the nail is R0.2 , The mold at this part wears quickly, and it is easy to bump and cause deformation during the production flow process.
The determination of the process plan
In order to adapt to mass production and improve efficiency, we have determined the following processes: (intermediate frequency furnace) heating/(cross wedge rolling) billet/(25000kN hot die forging press) bending/pre-forging/final forging/(3150kN double-point pressure Machine) Punching/trimming/normalizing/shot blasting inspection/precision pressing. In the technological process, heating billets are made of two pieces at a time, and the handles of the parts are slender, and the efficiency of free forging single billet production is low. The billet is rolled by cross wedge (as shown in Figure 2) and cut into two pieces on the rolling mill at the same time. Because the cross-section of the part changes greatly, from ∮55 to ∮23, it takes two wedge lifts to complete, so the rolling die processing and repairing are more difficult.
In addition to ensuring the size of the head and handle, the precision pressing process is more important to correct the position of the 10 nails, the fillet of the root, and the bending of the handle. Therefore, two movable standard pressing plates with 5 holes are used to ensure the position of the nails and the rounded corners of the roots, and improve the life of the forging die.
The key points of mold design and production
Usually, the design of the bending die only considers the shape of the extruded billet to be consistent with the forging. Due to the large difference between the thickness of the big end of the arm body and the handle, the shank of the bent blank will hang in the air when it is put into the pre-forging die. At this time, the metal flow in this part is too large. Therefore, the design of the press-bent blank must be placed on the pre-forging die so that its shape conforms to the shape of the pre-forging die.
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Link to this article：Analysis of forging process plan for automobile forgings
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