Study on the process of large blank forgings

2022-09-02

The blanks commonly used in mechanical processing are castings and forgings. Profile, powder metallurgy parts, stamping parts, cold or hot pressing parts, welding parts.

One of the trends in the development of modern mechanical manufacturing is to refine the blank so that its shape and size are close to the parts. In order to carry out less chip processing or even no chip processing, but because of blank manufacturing technology and equipment investment economic reasons. As well as mechanical and electrical products performance on parts processing accuracy and surface quality requirements are increasing, at present, many surfaces of the blank still have a certain processing allowance? In order to achieve the quality requirements of parts through mechanical processing. The difference between blank manufacturing size and part size is called blank processing allowance. In order to choose blank reasonably, it is usually necessary to consider the following aspects comprehensively.

(1) the size of the production program of parts the size of the production program to a large extent determines the economy of using a certain blank manufacturing method. The blank manufacturing method with higher precision and productivity should be selected when the production of the blank is larger. Can its greater investment in equipment and tooling pay off through reduced material consumption and lower machine plus T_ costs? And when the production batch of scutellaria is small. The blank manufacturing method with less investment in equipment and tooling should be chosen. Such as free forging and sand casting.

(2) blank materials and process characteristics

When selecting blank manufacturing method? First of all, the process characteristics of the material should be considered. Such as castability, malleability, weldability and so on. For example, cast iron and bronze cannot be forged, so only castings can be chosen for these materials. But the process characteristics of the material are not perfect. It is constantly changing with the improvement of the technological level of the process, for example. High speed steel and alloy tool steel used forgings as blanks for complex cutting tools long ago because of their poor castability. And now because of the improvement of precision casting level, even as complex as gear hob tools. High speed steel investment casting blanks are also available. Can be cut without cutting and directly grinding out the relevant geometric table. Important steel parts for its good mechanical properties. Regardless of its complex or simple structure, forging should be selected as blank, and should not be directly selected rolled profiles,

(3) The shape of the parts

The shape and size of the parts are also important factors in determining the blank manufacturing method. For example, the shape of the complex blank, generally do not use metal mold casting? Large size blank, often can not use die forging, die casting and investment casting. Sand casting is usually used for larger blanks weighing more than 100 kg. Methods such as free forging and welding. For the weight of more than 1500 kg of large forgings, the need for hydraulic molding into bad, high cost, but some special shape parts. Due to the difficulty of mechanical processing, blank manufacturing methods such as die-casting and investment casting were often used to minimize the machining allowance.

(4) Existing production conditions

When selecting blank? Should not be separated from the factory's production equipment conditions and technological level. But we should combine the development of products and create conditions actively. Adopt perfect blank manufacturing method. It is an important development direction of blank production to improve blank accuracy and realize less cutting and no machining.

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