How does a fitter draw a line? It's easy after learning the method

Scribing, as a basic process in the machining industry, is widely used in the production of small batches of products, and it is an important operating skill that a fitter must master. So how should a fitter draw a line? After learning the method, it is very simple. 1. What is scribing? According to the requirements of the drawing, the operation of using a scribing tool to draw a processing boundary or determine a reference point or line on a blank or semi-finished product is called scribing. The scribing work is not only performed on the surface of the blank, but also often performed on the processed surface. For example, in the process of mold processing and manufacturing, the scribing work is mostly performed on the processed template. 2. What is the effect of scribing? Scribing is not only performed on the surface of the blank, but also often on the surface that has been processed. For example, the processing line of the relationship between drilling and porous is drawn on the plane after processing, its main function is to determine the machining allowance of the workpiece, so that the mechanical processing has a clear size limit. It is convenient for complex workpieces to find the correct position on the machine tool by marking. It can find and process unqualified blanks in time to avoid reprocessing which may cause more serious economic losses. Using borrowed material to draw lines can remedy the rough blanks with little error, so that the processed parts can still meet the drawing requirements. 3. What are the specific requirements for scribing, which lines are smooth and uniform, and the size is accurate. In the three-dimensional scribing, the lines in the three directions of length, width and height are perpendicular to each other. When scribing, the line has a certain width, and the accuracy of scribing is impossible It is very high, so you should pay attention to the size measurement during processing to ensure the accuracy of the size. 4. What preparatory work needs to be done before marking. Tool preparation: Before marking, various tools must be selected reasonably according to the drawing of the workpiece marking and various technical requirements. Every tool must be inspected. If there is any defect, it should be repaired or replaced in time, otherwise the marking quality will be affected. The preparation of the work piece can be divided into two parts: the cleaning of the work piece and the painting of the work piece. (1) Workpiece cleaning: clean up flash, molding sand and oxide scale on the blank, and blunt and sharp edges of processed parts; (2) Workpiece coloring: In order to make the marking lines clearer, it is generally necessary before the work piece is marked. When applying paint, the type of paint is generally selected according to the use occasion. The surface of the blank uses lime water (white ash, latex and water), lithopone (zinc sulfide, barium sulfate, latex and water), and chalk. The processed surface uses copper sulfate (copper sulfate and water), blue oil (gentian purple plus shellac or alcohol, green oil (malachite green plus worm cavity or alcohol). The precision surface uses anhydrous paint (banana water, resin, fire Cotton glue and methyl violet). 5. The specific steps of the fitter's marking (1) See the pattern clearly and understand in detail the parts that need to be marked on the workpiece; clarify the role and requirements of the workpiece and the relevant parts of the marking in the product, and understand Relevant follow-up processing technology; (2) Determine the marking benchmark; (3) Preliminarily check the error of the blank. When the shape, size and position of the workpiece are in error, determine the plan for borrowing materials; (4) Correctly place the workpiece and select tools; ( 5) First draw the reference line and position velvet, then draw the processing line, that is, first draw the horizontal line, then draw the vertical line, the diagonal line, and finally draw the circle, arc and curve; (6) Carefully check the accuracy of the line and whether there is any Line omissions, right or wrong lines or omissions should be corrected in time to ensure the accuracy of the line; (7) Punch holes on the lines. Punch holes must be punched, and the rough surface must be deeper. The processed or thin plate parts must To be more shallow, there is no proofing on the finishing surface and soft materials. Previous post: A bench vise that seems to be simple, do you really understand it as a fitter?