(1) Cleaning and inspection of workpieces; (2) coloring the workpiece; (3) The method and steps of installing the center block in the center of the workpiece hole; (1) Selection of marking datum; (2) Alignment and borrowing of marks; (3) Marking step: the error of the blank is preliminarily checked by reading the pattern, and the workpiece is cleaned and colored. According to the shape and size of the workpiece, determine the appropriate marking datum, correctly place the workpiece, and select tools for marking. Check the correctness of the scribing in detail, and check whether there are any missing lines on the scribing lines. (2) sawing. Features of sawing: sawing tools can cut off all kinds of raw materials or semi-finished products, redundant parts of the workpiece, and saw grooves on the workpiece. 1. Structure of hand saw: saw bow and saw blade 1. Specification of saw blade: 300mm long, 0/0 ~ 25mm wide and 0.6 ~ 10~25mm 2 thick. Sawtooth angle, rake angle γ, wedge angle β and back angle α 3. When sawing soft materials, large surfaces or large surfaces, the sawtooth thickness and saw blade should be correctly selected. Fine-toothed saw blades are used to saw hard materials, pipes or thin materials. 4. Sawing method (1) Sawing method: it is divided into far saw and near saw, and the sawing angle is about 15 degrees. If it is too large, sawing is not easy and smooth; However, the sawing angle should not be too small, otherwise, because there are many teeth in contact with the workpiece at the same time, it is not easy to cut into the material, and it is easy to run off when sawing for many times, which will cause many saw marks on the surface of the workpiece and affect the surface quality. ⑵ The sawing speed is even and the pressure is small. (3) Sawing methods for various workpieces. The safety technology of sawing and the clamping of civilized production workpiece should be firm, pay attention to the installation of workpiece and saw blade, pay attention to the straightness of saw seam in time, and correct it in time, so as to prevent the saw blade from breaking and popping up. Demonstration operation (1) Installation of the saw blade When installing the saw blade, the saw teeth should face forward and cannot be installed backwards. The saw blade should be installed straight and without distortion, and the tightness should be appropriate, otherwise it will cause the saw blade to break and warp straightly. Generally, it is difficult to move the saw blade by hand. If the saw seam exceeds the height of the silver bow, the saw blade can be installed at a 90-degree angle with the silver bow. ⑵ When sawing, hold the saw standing posture, hold the silver handle with your right hand, gently hold the front end of the saw bow with your left hand, and the right hand mainly controls the movement of the saw bow. The left hand cooperates with the right hand to stabilize the saw bow and gently press it to play an auxiliary role. This is a work schedule. Both hands should put pressure on the saw bow, and sawing is not a work schedule. No pressure. Standing posture is the posture you stand when you are wrong. When cutting, the operator stands on the left side of the longitudinal center line of the vise, with his body deflected by about 45, his left foot stepping forward for half a step, his center of gravity inclines to his right foot, his feet naturally stand firm, and his eyes rest on the sawing line of the workpiece (Figure 4-23). (3) Sawing is the beginning of sawing, and the quality of sawing directly affects the quality of sawing. When pulling the saw, the angle between the saw blade and the workpiece surface should be small, preferably not more than 15. If the angle is too large, the sawtooth is easily caught by the edge of the workpiece. The pressure of obtaining evidence should also be less and the speed should be slightly slower. The reciprocating stroke should be short. In order to obtain evidence smoothly and accurately, the thumb tip of the left hand can be placed flat on the edge of the silver wire, and the nail can be loosely placed on the smooth part above the sawtooth to guide the saw blade to cut in. (4) There are two ways to move the saw bow when pushing the saw: one is linear motion, which is suitable for workpieces with flat or thin bottom; The other is that the saw bow can swing up and down, which can reduce the sawing resistance and improve the sawing efficiency, and is suitable for thick-walled workpieces. 5] Sawing is the end of silver cutting. When the workpiece is about to be sawed off, pay attention to sawing. At this time, the intensity should be small and the speed should be slow. Hold the part to be sawed off with your left hand until it is sawed off. put forward
1. Basic knowledge 1. Characteristics and application of filing: filing is a processing method of cutting the surface of workpiece with a file to achieve the required size, shape, position and surface roughness. 1. Names and specifications of each part of file (1) (2) Tooth marks of file (3) Types of file: ordinary file, special file and whole file (4) Thickness and selection of file: including the selection of file shape and file thickness and specification. 5. Proper use and maintenance of the file: the file cannot be stained with water or oil, and the file cannot be used to file the hardened surface of the workpiece or the hard surface of the blank. Make full use of the effective length of the file. It is necessary to use a wire brush to remove the metal chips in the tooth slot in time. 3. Filing method (1) Clamping of workpiece. 2. Correct archiving method (3) Archiving speed. 3. Filing methods and inspection of various surfaces (1) Filing methods and inspection of large planes (2) Filing methods and inspection of internal and external circular surfaces (5) Safety technology and civilized production of filing: the file handle cannot be exposed outside the clamp table, the file without handle cannot be used, and the file handle cannot touch the workpiece during filing, which is not allowed. Second, the demonstration operation
1. Disassembly method of file handle.
Hold the handle with the left hand, insert the file tongue into the file handle with the right hand, and gently bump the lower end of the file vertically on the clip with the right hand.
It's tight When removing the handle, put the handle on the vise mouth and tap it out gently.
2. Filing posture and operation method.
When filing, the person's standing position is similar to that of chisel cutting. When filing, we should make full use of the full length of the file and work with all files. At the beginning, lean forward 10 or so, and contract your right elbow backwards as far as possible. In the first third stroke, the body gradually leans forward to about 15, making the left knee slightly bent; Secondly, in the third stroke, the right elbow is pushed forward, and the body gradually leans forward to about 18; Finally, when the third seed is selected and the right wrist pushes the gear, the body will retreat to the position of 15 with the help of the reaction force of the gear. After the file is scratched, lift the file slightly and return to the original position and posture. In order to smooth the surface, we must correctly grasp the balance of filing force and make the file stable. There are two forces when filing: horizontal thrust and vertical pressure. The thrust is mainly controlled by the right hand, and its magnitude must be greater than the cutting resistance, so that the chips can be filed off. The pressure is controlled by two hands, which is used to make the file teeth go deep into the metal surface. Because the length of the workpiece protruding from both ends of the tool changes at any time, the pressure of both hands must be kept in balance with the change, so that both hands can always remain horizontal when filing. 3. Method and inspection of leveling and filing
During rough machining, the workpiece is filed in two intersecting directions. This intersecting filing method can judge the filing surface.
In high and low conditions, in order to file high, the workpiece is filed along the length direction with a file during finishing, and straight file marks can be obtained after filing, which is neat and beautiful; To correct the plane or size, push files can be used to improve the accuracy or reduce the surface roughness. When filing a plane, always check whether the filing surface of the workpiece is smooth. Generally, steel tape measure or square ruler is used to check by light transmission method. Put the ruler close to the working face, and check it in many places along the longitudinal, transverse and oblique directions. When checking the angle, you can use a square ruler, protractor or sample ruler to aim at the angle and check it by light transmission method. 4. Filing method and inspection of outer arc
The filing of the outer arc surface is to file the part of the arc into a polygon very close to the arc. This method has high efficiency and is suitable for the rough machining stage of circular arc surfaces. File along the arc surface, also known as rolling file method, when filing, the file should complete two actions at the same time: advancing and swinging around the arc center of the workpiece, which is used in the finishing stage of the arc surface. The inspection of the outer arc surface should use the arc template ruler close to the machined surface and adopt the light transmission method.
Exercise 1. Overview of basic knowledge 1.
(1) Several methods of hole processing: drilling, reaming and reaming (2) Characteristics of hole processing on drilling machine (3) Comparison with other machine tools.
4. Drilling machine
Bench drilling machine, vertical drilling machine, radial drilling machine
3. Twist drill
⑴ Name and function of each part: It consists of working part, neck and handle ⑴ Geometric angle analysis of drill ⑴ Grinding of twist drill.
2. Drilling method (1) Auxiliary tools for drilling and workpiece clamping (2) Drilling methods for various holes.
5. Safety technology and civilized production of drilling (1) Before drilling, clean up the work site (2) Fasten sleeves and wear working caps (3) Check before starting (4) Clamp the workpiece (5) Do not blow with your mouth when cutting, and demonstrate the operation;
1. Grinding of drill bit.
The rake face of the drill bit contacts the grinding wheel for grinding, and the right hand rotates slightly around the axis of the drill bit. The left hand swings slightly up and down, so that the included angle between the axis of the drill bit and the generatrix of the grinding wheel cylindrical surface is equal to half of the top angle 2φ of the drill bit, so that the top angle, back angle and bevel angle of the cross blade can be ground at the same time. When grinding one side, grind the other side, and check the correctness and symmetry of the angle at any time. In order to prevent heating annealing, it is necessary to cool with water.
3. Comparison between drilling and reaming.
(1) Machining nuts with bottom hole diameter of φ 12mm.
After marking out the center of the hole, punch a hole in a larger place in the center of the hole first, so that the horizontal blade will fall into the perforated cone hole ahead of time, and the hole is not easy to deviate from the center. At the same time, draw a circle of φ 12 mm, and carefully correct it when clamping the workpiece, so that the center line of the hole is perpendicular to the drill floor, and the clamping is stable. When drilling begins, let the drill bit touch the workpiece slowly. First, drill a shallow pit and check whether the center of the hole deviates from the drawn circle line. If there is any deviation, drill holes after correction. When the hole is about to pass, the feed speed must be reduced to avoid affecting the machining quality and damaging the drill bit.
⑵ Drill 6 mm pre-drilling first, and then drill with φ 12mm bit. Compared with direct drilling φ 12mm, the former is labor-saving, with higher round hole accuracy and lower surface roughness.
3. Reaming holes
Roughly reaming φ 12mm hole, first drilling φ 1 1.6mm hole, then reaming with machine reamer. When reaming, the reamer should not be reversed in the hole. At the same time, pay attention to stop after reaming to avoid pulling the hole surface. Such as adding mechanical oil for lubrication and cooling to reduce surface roughness. Compared with various drilling methods, the reaming accuracy is higher and the surface roughness is lower.
4. Student operation
(1) Content: Machining the bottom hole of hexagon nut φ 12mm.
⑵ Requirements: The method of sharpening the drill bit and drilling is basically correct, the drilling is perpendicular to the datum plane, and the aperture is consistent with the diameter of the drill bit. Tapping Tapping I. Basic knowledge 1. Components and types of tapping (1) taps: cutting parts and calibration parts: machine taps and manual taps.
⑵ Working principle and geometric angle of tap: cutting cone angle, rake angle, rake angle, cutting edge direction and inverted cone.
⑶ Determination of thread bottom hole diameter Brittle material: D bottom =D- 1.05P Tough material: D bottom =D-PD bottom-bottom hole diameter D- thread diameter P- pitch.
(4) the tapping operation method and the method of removing the tap.
4. A set of silk
(1) Die Die is a tool for processing external threads. It is made of alloy tool steel and quenched. The die consists of a cutting part, a calibration part and a chip removal hole. ⑵ Determination of the diameter of round rod D =d-0. 13P d Rod-round rod diameter d- thread diameter P- pitch (3) Method 2 of tapping. Demonstration operation
1. Tapping method
After chamfering the tapping end hole, make the tap coaxial with the bottom hole of the workpiece. The square tenon of the tap is sleeved in the square hole of the reaming hand, and the reaming hand is pulled clockwise. When you start slapping, you should use force, and both hands should use force evenly to keep balance. When the tap cuts into several teeth, as long as the reaming hand is turned, it will be reversed 1/4 ~ 1/2 every positive turn, so as to remove chips. If coolant is added for lubrication, the resistance can be reduced. When tapping a blind hole, it is especially necessary to remove chips to avoid blocking the chip groove and damaging the tap.
The method of machine attack.
Chamfer the end hole tapped by the machine and keep the tap and threaded hole coaxial. Choose a lower speed for the machine.
Attack, and pay attention to frequent inversion, in order to facilitate chip removal. The calibration part of the tap can't protrude completely, otherwise it will cause disorderly screwing when backing out the tap. When tapping the machine, adding cooling lubricant can reduce the cutting resistance.
[14] threading method
Chamfering should be carried out on the round rod of the set of wires, so that the end face of the die is perpendicular to the axis of the workpiece. At the beginning of thread processing, axial force should be applied to the die. When the cutting part of the die completely cuts into the workpiece, no more pressure should be applied. When turning threads, if coolant is added for lubrication, the cutting resistance can be reduced.
Intermediate fitter I. Knowledge requirements
1. Names, uses, use and maintenance methods of commonly used measuring instruments.
2. The structure, use, adjustment and maintenance methods of common tools and fixtures (including combined fixtures).
3. Basic knowledge of metal cutting principles and tools.
4. Basic knowledge of hydraulic transmission.
5. Have knowledge of drawing complex part drawings and simple assembly drawings.
6. Working principle and structure of general mechanical equipment (pumps, fans, freezers and typical machine tools, etc.). ).
7. Principle and structure of internal combustion engine.
8. Prepare the basic knowledge of mechanical equipment assembly process specification.
9. Marking methods for complex workpieces (including large and deformed workpieces).
10. Types and uses of cams, calculation and marking methods of dimensions of each part; Marking method of curve; Expansion method of cone and polyhedron.
1 1. Balance types, basic principles and correction methods of rotating parts.
12. knowledge of babbit casting of bearing bush.
13. Assembly method of precision sliding bearing and rolling bearing.
14. Quality requirements and inspection methods of gearbox assembly.
15. Factors affecting general mechanical accuracy, methods of checking accuracy and factors affecting measurement accuracy.
16. the influence of machine tool accuracy on workpiece accuracy, and the methods to improve workpiece machining accuracy and refine surface roughness.
17. working principle, structure and application knowledge of hydrostatic guide rail and hydrostatic bearing.
18. Methods to prevent deformation when machining workpieces.
19. Basic knowledge of CNC machine tools.
20. General machine tool processing knowledge, general workpiece processing technology.
2 1. Knowledge of production technology management.
Second, the skill requirements
1. Understand more complicated assembly drawings and draw complicated parts drawings.
2. According to the technical requirements of the workpiece, prepare the processing technology.
3. Design and draw a simple process equipment diagram.
4. Drill small holes, inclined holes, deep holes, holes, butt holes and cross holes that meet the requirements of drawings on complex workpieces.
5. Three-dimensional scribing of workpieces with complex shapes.
6. Grinding the inspection mandrel with taper and the spindle hole of high-precision machine tool, the contact quality, accuracy and surface roughness meet the technical requirements.
7. According to the technical requirements of mechanical equipment, prepare the assembly process sequence.
8. Dynamic and static balance of rotating parts.
9. Test the performance of various hydraulic components on the hydraulic test bench.
10. Assemble compressor, air hammer, press and high-pressure pump, etc. , meet the technical requirements.
1 1. Assemble a typical machine tool and check the accuracy.
12. According to the quality of the workpiece and the operation of the machine tool, distinguish whether the machine tool works normally.
Three. Examples of works
1. leveling the leveling ruler or bridge leveling ruler with the length of 1500mm, with the accuracy of 1.
2. The marking and manufacturing of disc cam meet the technical requirements.
3. Draw the processing line of roots blower shell and blade.
4. Drilling of complex hydraulic valve body (such as control box).
5. Drill and ream three 620mm holes on a steel plate with a thickness of 20 mm, with a center distance of 100mm and a surface roughness of Ra3.2? M, what is the tolerance value of the position? 0. 1 mm.
6. Assemble a horizontal lathe, which meets the technical requirements.
7. Assemble the guideway grinder to meet the technical requirements.
8. Assemble a 7.36kW diesel engine to meet the technical requirements.
9. Machining workpieces and assembly parts with corresponding complexity.