The selection of sample materials depends on the batch of forgings. For large batch or shaped forging products, considering the long-term use requirements of the sample material, it is recommended to select 1? 3mm steel plate or 2? 5mm aluminum plate; For single piece or small batch forgings, due to the short service time, in order to facilitate cutting, choose 0.3? 1mm steel plate or 1mm aluminum plate; For disposable cold forgings, instead of model inspection, cardboard and linoleum materials can also be used to make models. Its shape is identical to that of a forging. During inspection, the model is placed on the forging for comparison.
(1) For some free form forgings with large changes in shape or cross-section, it is necessary to design and draw a model. Due to the relatively simple shape and structure of free forging, only shape models can be used. Generally speaking, part drawings are the basis for drawing template drawings, which are directly drawn on the template material. The shape of the template can be consistent with the shape of the part after processing. Small screw holes, fine grooves, small fillets, and chamfers on parts do not require W (it is practically impossible to forge). At the same time, indicate the value of each surface on the forging drawing. When using, simply place the template directly on these forgings to visually see and estimate the machining allowance for each part of the forging. If two templates need to be aligned, use thick solid lines to draw alignment positioning lines and mark them on the template. Due to the application of templates in the entire process of forging forming and processing, when designing the overall structure of the template, consideration should also be given to facilitating the use of the production site, that is, additional structures should be designed to facilitate the flexible movement of the template on the forging.
(2) Fabrication of inspection templates for die forgings The templates for die forgings are divided into outline templates, internal templates, and cross-sectional templates. The type line of the external template is the same as the contour line of the component under test. The type line of the internal template is the same as the concave contour line of the component under test. The contour line of the cross section template is the same as the contour line of the component under test. Key points for forging the template:
① The type line of the template. Generally, the drawing is based on the known contour lines on the forging drawing. Sometimes, the foot should be the actual shape of each cross section that is not expressed in the cold forging drawing and needs to be checked. When specifically drawing model lines, since most cross sections are closed, two-way measurement cross sections, the lines on the parting surface are generally used as the boundary. The cross-sectional contour line is divided into two parts, and the model lines are drawn separately to form a group of models on the same cross-sectional area. Then, the inner and outer contour lines are drawn based on one within the cross-sectional area.
② Shape structure. Die forging inspection templates generally need to be matched with a certain measuring frame, so their shape, structure, and size are determined by the measuring frame. For the rest, consider whether the deformation, positioning, measurement, and measurement of the model are convenient.
③ Determine the baseline and positioning structure. The reference is uniformly determined based on the position of the sample on the measurement frame. You can draw three positioning holes near the model line to match the positioning pins on the measuring tool.
④ Draw the tolerance of the sample according to the tolerance and technical requirements of the forging. ⑤ Benchmarking.