Introduction to the marking operation of the tongs

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Introduction to fitter scribing operation

the operation of drawing machining graphics or machining boundaries on blanks or semi-finished products is called scribing. Its function is: Address: room 2001, Shihua International Plaza, No. 2659 Shuichan Road, Shanghai (1) as the basis for processing; (2) Check the shape and size of the blank, and the mechanical connection deformation measuring instrument of the reinforcement is composed of the host, high-precision electronic displacement meter, fixture, display instrument, etc. to eliminate the unqualified blank; (3) Allocate machining allowance of workpiece reasonably

otherwise, the accuracy of the experimental results will be affected

1 scoring tools and methods

methods of scoring with a scoring needle when installing a cold and hot impact testing machine

common scoring tools

common scoring tools include scoring needle, scoring gauge, scoring card, scoring disc, square box, flat plate, sample punch, etc

2 selection of scribing datum

when scribing, the remaining dimension lines should be drawn based on a line or a surface on the workpiece. Such lines (or surfaces) are called scribing datum. The marking datum shall be consistent with the design datum as far as possible. The datum of the blank generally selects its axis or installation plane as the datum. The bearing seat shown in Figure 1 should be based on the design datum plane B and line a (symmetry line), so that all dimension limits can be drawn according to the dimensions on the drawing

Figure 1 scribing datum

3 scribing steps

scribing is divided into plane scribing and three-dimensional scribing. Plane scribing is scribing on a surface of the workpiece, and the method is similar to mechanical drawing. Solid scribing refers to scribing on several surfaces of the workpiece, such as in the length, width, height direction or other inclined directions. The three-dimensional marking of workpieces is usually carried out on the marking platform. When marking, workpieces are usually supported by jacks, and some workpieces can also be supported by square boxes, V-shaped blocks, etc

1) preparation before scribing

the blank shall be cleaned before scribing (remove the dirt and burrs on the surface of the blank), and the scribing surface shall be coated with a thin and uniform coating, and the blank surface shall be coated with white paste or chalk; The processed surface is coated with purple paint (gentian violet plus shellac and alcohol) or green paint (malachite green plus shellac and alcohol). For the workpiece with holes, the holes should also be blocked with lead blocks or wood blocks in order to determine the center of the hole

2) three dimensional scribing operation

Figure 2 shows the three-dimensional scribing operation method of the bearing seat, which belongs to blank scribing. The marking and specific steps are shown in figures 2b to F

Figure 2 three dimensional marking of bearing seat

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