The processing of metal stamping parts refers to the processing method to obtain the overall dimensions and surface quality of the parts through the processing of stamping parts. It mainly includes: forming processing, milling processing, rolling processing, etc. Stamping processing has high precision, strict precision requirements and wide application range. It is applicable to the forming processing of mechanical parts with different degrees of lightweight needs. It is one of the important manufacturing methods of high-precision mechanical parts. The deformation of CNC stamping parts (dies) and ordinary stamping parts during milling and rolling process on precision machine tools and other processing equipment is usually called milling deformation. Due to its nature, the error of the overall dimensions of the parts formed after milling cannot be too large, especially when large deformation occurs under the condition of forming complex shapes or affects the appearance quality of the parts, It must be milled by laser assisted or mechanical assisted means.
1. Milling deformation
Milling deformation generally occurs between the part surface and the contour, between the plane and the arc, and mainly occurs under the condition of forming complex shapes. In terms of shape, such as cone, arc, right angle cone, etc., the deformation generated in the milling process is generally plastic deformation or elastic deformation, which is generally completed by tools such as milling cutter or fixture, and also by diamond milling cutter and laser milling cutter; From the perspective of structure, it mainly occurs in the surface treatment stage after milling and the final processing stage after machining. During processing, the workpiece is first unloaded from the workbench, and then fixed on the workbench by the milling cutter for milling and a series of other processes before the next process.
2. Milling method
Milling deformation of metal stamping parts mainly includes: surface deformation, thread deformation, interference between convex and concave chucks, internal and external circles, internal hole diameter deviation, end face deviation, etc. Common methods include internal hole diameter milling, end face milling, thread milling, etc. The inner circle and outer circle are common deformation forms in machining. The inner surface processing of the inner hole refers to the complete processing and shaping of the inner surface of the inner hole of the part through drilling; The internal surface processing (rolling) of end face is a processing method that uses tools such as collets (convex and concave collets), clamps, guides, etc. to mill the plane or grooved part (convex and concave collets) of parts into the contour or surface morphology.
3. Tool performance
The machining deformation of metal stamping parts is related to the tool selection. In the process of punching, boring and milling, the tool performance is one of the main factors that affect the precision and surface quality of parts. It directly affects the machining efficiency and precision of parts as well as the surface quality of parts. The factors that determine the tool performance mainly include the following aspects: tool material, tool and workpiece fixture, and the operating structure between tool and workpiece. Tool material: in the process of punching, boring and milling, the tool material shall have good wear resistance, heat resistance and oil resistance, hardness, heat resistance and wear resistance, small wear, small deformation and other characteristics; When the tool structure is made of multilayer cemented carbide, the cutting edge should be properly ground; The cutter structure generally adopts spiral edge or cylindrical edge When the cutter structure adopts three-layer cutter, it shall be noted that the cutter shall be chamfered as much as possible; The replaceable cutter is an indispensable part of improving the milling quality in the milling process, and the replaceable cutter can greatly reduce the milling cost. Tool structure: With the continuous diversification of tool structure types and the increase of complex processing procedures, new requirements are put forward for tool structure. When using tool structure, attention must be paid to the selection on the premise of ensuring the processing quality.
4. Treatment after milling
When the parts are partially trimmed after processing, they usually need to be polished and painted to improve the surface quality. The milled parts shall be subject to surface dressing within 24 hours after turning, then necessary polishing treatment, painting treatment and local dressing to improve the quality of parts. In order to obtain the best precision of the milled parts, the necessary surface finishing must be carried out on the parts.
5. In case of serious milling deformation of large and complex structural parts, large spacing milling machine can be used for precise milling.
For large and complex parts, it is usually necessary to use multiple machine tools to complete milling. Because the precision and cutting ability of the milling machine are relatively strong, it is necessary not only to use the corresponding CNC machine tools, but also to use a special milling machine to process parts in order to achieve the integral milling of parts. At present, the mainstream technologies in the world include: milling machine – milling trolley – multi station CNC machine tool, CNC turret trolley, machining center – CNC milling machine – machining center, etc.