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Determination of the shape and size of the blank material

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Update time : 2020-01-01 15:49:00
The shape and size of the blank are basically determined by the shape and size of the part. The main difference between a part and a blank is that a certain machining allowance is added to the surface of the part to be processed, that is, the blank allowance. When manufacturing blanks, errors also occur. The dimensional tolerances of blank manufacturing are called blank tolerances. The size of the blank machining allowance and tolerance directly affects the labor of machining and the consumption of raw materials, thereby affecting the manufacturing cost of the product. Therefore, one of the development trends of modern machinery manufacturing is to make the shape and size of the blank consistent with the parts as much as possible through the refinement of the blank, and strive to achieve less and no cutting. The size of the blank machining allowance and tolerance is related to the manufacturing method of the blank. During production, it can be determined by referring to the relevant process manual or relevant enterprise and industry standards.

After the blank machining allowance is determined, in addition to adding the blank machining allowance to the corresponding machining surface of the part, the effects of process factors such as manufacturing, machining and heat treatment of the blank must also be considered. In the following, only from the perspective of the machining process, the issues that should be considered when determining the shape and size of the blank are analyzed.

(1) Setting of craftsmanship

For some parts, due to the structural reasons, it is not easy to clamp and stabilize during processing. In order to facilitate clamping quickly, a boss can be made on the blank, which is the so-called process hook. The craftsmanship is only used when clamping the workpiece. After the part is processed, it is generally cut off, but it can be retained if it does not affect the performance and appearance quality of the part.

(2) the use of overall blanks

During machining, parts such as the three-watt bearing in the spindle part of the grinding machine, the connecting rod of the engine, and the opening and closing nut of the lathe are sometimes encountered. In order to ensure the processing quality and convenient processing of such parts, it is often made into an overall blank, and cut after processing to a certain stage.

(3) the use of blanks

In order to facilitate the clamping during the processing, for some small parts with relatively regular shapes, such as T-shaped keys, flat nuts, small spacers, etc., multiple pieces should be combined into a blank, which will be processed after a certain stage or most of the surface processing After finishing, it is processed into a single piece.

After determining the type, shape and size of the blank, a blank drawing should be drawn as the product pattern of the blank production unit. Drawing the blank drawing is based on the part drawing and adding the blank allowance to the corresponding machining surface. However, the specific manufacturing conditions of the blank should also be considered when drawing, such as the casting and forging conditions of the holes in the casting, the holes in the forging and the blanks, flanges, etc. Slope) and fillet; the position of the parting surface and parting surface, etc. And the two-dot chain line is used to show the surface of the part in the rough drawing to distinguish the machined surface from the non-machined surface.
https://www.infignos.com/templates/updatelistingnow.cfm?email=ryanlee901213@gmail.comShenzhen Kangda Precision Manufacturing Co.,Ltd.,Machining Manufacturer,Shenzhen,FL