The main research results of the significance of machining technology are as follows:
1. The technology of machining enterprises is an important factor in the mechanization of product parts production, which directly affects the smooth progress of the entire social production management process
2. The processing technology can comprehensively and effectively monitor the safety factor of the processing process.
Mechanical faults are found at any time, and timely maintenance is required to eliminate potential safety hazards. Scientific and reasonable processing technology can effectively improve the production management efficiency of enterprises, improve the quality of their products and services, and meet processing requirements.
Mechanical processing is an important step in the manufacture of workpieces or parts. The process that can directly change the shape, size and surface quality of the blank through processing is called the research process of processing product production technology development. For example, the common part of the processing and production process is roughing, finishing, assembly, inspection and packaging, which is the social development research process of processing in our country.
The research process of processing technology development is based on the processing process, changing the shape, size, relative position and nature of the socialized production and operation service object of the enterprise, making it a finished or semi-finished product. According to the number of products, equipment conditions and the quality of workers, technicians can determine the adopted process through research and analysis, and conduct research on relevant management issues, and write the main work content into the process design files. These information data files are Called a process control program, it is more targeted.
1. What are the three methods of workpiece clamping?
{1. Clamp in the fixture; 2. Directly find the correct clamping; 3. Mark the line to find the correct clamping}
2. What does the process system include?
{machine tool, workpiece, fixture, tool}
3. What is the composition of the cnc machining process?
{roughing, semi-finishing, finishing, super-finishing}
4. How are benchmarks classified?
{1. Design basis 2. Process basis: process, measurement, assembly, positioning: (original, additional): (rough basis, fine basis)}
What does the machining accuracy include?
{1. Dimensional Accuracy 2. Shape Accuracy 3. Positional Accuracy }
5. What are the original errors in the machining process?
{Principle error, Positioning error, Adjustment error, Tool error, Fixture error, Machine tool spindle rotation error, Machine tool guideway guide error, Machine tool transmission error, Force deformation of process system, Thermal deformation of process system, Tool wear, Measurement error, Workpiece residual stress error caused by ·}
6. The effect of process system stiffness on machining accuracy (machine tool deformation, workpiece deformation)?
{1. Workpiece shape error caused by position change of cutting force action point 2. Machining error caused by change of cutting force 3. Machining error caused by clamping force and gravity 4. Influence of transmission force and inertia force on machining accuracy}
7. What are the guide errors and spindle rotation errors of machine tool guide rails?
{1. The guide rail mainly includes the relative displacement error between the tool and the workpiece in the error-sensitive direction caused by the guide rail. 2. Spindle radial runout, axial runout, and inclination swing}
8. What is the phenomenon of “error re-mapping”? What is the error remap coefficient? What are the measures to reduce error re-mapping?
{Due to the change of the error deformation of the process system, part of the blank error is reflected on the workpiece. Measures: increase the number of passes, increase the rigidity of the process system, reduce the feed rate, and improve the blank accuracy}
9. Analysis of transmission error of machine tool transmission chain? Measures to reduce the transmission error of the transmission chain?
{Error analysis: that is to measure the angle error Δφ of the end element of the transmission chain
Measures: 1. The fewer the number of transmission chain parts, the shorter the transmission chain, the smaller the Δφ, the higher the accuracy 2. The smaller the transmission ratio i, especially the small transmission ratio of the first and last ends, 3. Because the end piece in the transmission part The error affects the most, so it should be as accurate as possible 4. Use a correction device }
10. How to classify processing errors? Which errors are constant errors? Which errors are systematic errors of variable value? Which errors are random errors?
{System error: (constant system error variable value system error) random error
Constant system error: machining principle error, machining error caused by machine tool, tool, fixture manufacturing error, force deformation of process system, etc.
Variable value system error: wear of props; thermal deformation error of tools, fixtures, machine tools, etc. before thermal equilibrium
Random errors: copying of blank errors, positioning errors, tightening errors, errors of multiple adjustments, deformation errors caused by residual stress }
11. What are the ways to ensure and improve machining accuracy?
{1. Error prevention technology: reasonable use of advanced technology and equipment, direct reduction of original errors, transfer of original errors, equalization of inferior original errors, and equalization of original errors
2. Error compensation technology: online detection, automatic grinding of couple parts, and active control of the decisive error factors}
12. What are the contents of the machined surface geometry?
{geometric roughness, surface waviness, grain orientation, surface defects}
13. What are the physical and chemical properties of the surface layer material?
{1. Cold work hardening of the surface layer metal 2. Metallographic deformation of the surface layer metal 3. Residual stress of the surface layer metal}
14. Try to analyze the factors that affect the surface roughness of machining?
{Roughness value is determined by: height of cutting residual area Main factor: tool nose arc radius main declination angle secondary declination feed amount Secondary factor: increase cutting speed appropriately select cutting fluid appropriately increase the rake angle of the tool to improve the cutting edge of the tool Grinding quality }
15. Try to analyze the factors that affect the surface roughness of grinding?
{1. Geometric factors: the effect of grinding amount on surface roughness 2. The effect of grinding wheel particle size and grinding wheel dressing on surface roughness 2. The effect of physical factors: plastic deformation of surface metal: grinding amount and selection of grinding wheel}
16. Try to analyze the factors that affect the cold work hardening of the machining surface?
{Influence of cutting amount Influence of tool geometry Influence of machined material properties}
17. What is grinding and tempering burn? What are grinding and quenching burns? What is Grinding Annealing Burn?
{Tempering: If the temperature of the grinding zone does not exceed the transformation temperature of the quenched steel, but has exceeded the transformation temperature of the martensite, the martensite of the metal on the surface of the workpiece will be transformed into a tempered structure with lower hardness. The temperature of the cutting zone exceeds the phase transition temperature, and coupled with the cooling effect of the coolant, the surface metal will have a secondary quenched martensite structure, and the hardness is higher than the original martensite; Annealing of tempered structure with lower hardness than the original tempered martensite: If the temperature of the grinding zone exceeds the phase transition temperature and there is no coolant during the grinding process, the surface metal will appear annealed structure, and the hardness of the surface metal will be sharp. decline}
18. Prevention and control of machining vibration
{Eliminate or weaken the conditions for machining vibration; improve the dynamic characteristics of the process system, improve the stability of the process system, and use various vibration and vibration damping devices}
19. Briefly describe the main differences and applications of machining process cards, process cards, and process cards.
{Process card: Single-piece small batch production using common processing methods Machining process card: Mid-batch production process card: Large-scale mass production requires strict and meticulous organization}
*20. Rough benchmark selection principle? Refined benchmark selection principle?
{Rough datum: 1. The principle of ensuring mutual position requirements; 2. The principle of ensuring the reasonable distribution of cnc machining china allowances on the machined surface; 3. The principle of facilitating workpiece clamping; 4. The principle that rough datums generally cannot be reused Fine datum: 1. Principle of coincidence of benchmarks; 2. Principle of unified benchmark; 3. Principle of mutual benchmark; 4. Principle of self-based benchmark; 5. Principle of easy clamping }
21. What are the principles of the process sequence?
{ 1. Process the datum surface first, then process other surfaces; 2. In half of the cases, process the surface first, and then process the hole; 3. Process the main surface first, then process the secondary surface; 4. Arrange the roughing process first, then arrange Finishing operations }
22. How to divide the processing stage? What are the benefits of dividing the processing stage?
{ Processing stage division: 1. Roughing stage, semi-finishing stage, finishing stage, precision finishing stage, which can ensure sufficient time to eliminate thermal deformation and eliminate residual stress caused by roughing, so as to improve the subsequent machining accuracy. In addition, when the blank is found to be defective in the roughing stage, it is not necessary to carry out the processing of the next processing stage, thereby avoiding waste. In addition, equipment can be used reasonably, low-precision machine tools are used for roughing and precision machine tools are specially used for finishing to maintain the precision level of precision machine tools; human resources are reasonably arranged, and high-skilled workers are specialized in precision and ultra-precision machining, which is very important to ensure It is very important to improve the quality of products and improve the level of craftsmanship. }
23. What are the factors that affect the process allowance?
{1. Dimensional tolerance Ta of the previous process; 2. Surface roughness Ry and surface defect depth Ha generated by the previous process; 3. Spatial error left by the previous process}
24. What does the composition of the working hour quota include?
{T quota = T single piece time + t quasi-final time / n pieces}
25. What are the technological ways to improve productivity
{1. Shorten the basic time; 2. Reduce the overlap between the auxiliary time and the basic time; 3. Reduce the time for arranging the work site; 4. Reduce the preparation and finishing time}
26. What are the main contents of the assembly process regulations?
{1. Analyze product drawings, divide assembly units, and determine assembly methods; 2. Draw up assembly sequences and divide assembly processes; 3. Calculate assembly time quotas; 4. Determine assembly technical requirements, quality inspection methods and inspection tools for each process; 5. Determine the transportation method of assembly parts and the required equipment and tools; 6. Select and design the tools, fixtures and special equipment required in the assembly process}
27. What should be considered in the assembly process of the machine structure?
{1. The machine structure should be able to be divided into independent assembly units; 2. The repair and precision machining during assembly should be reduced; 3. The machine structure should be easy to assemble and disassemble}
28. What does the assembly accuracy generally include?
{1. Mutual position accuracy; 2. Mutual motion accuracy; 3. Mutual cooperation accuracy}
29. What problems should be paid attention to when looking for the assembly dimension chain?
{1. The assembly dimension chain should be simplified as necessary; 2. The assembly dimension chain consists of “one piece and one link”; 3. The “directivity” of the assembly dimension chain is in the same assembly structure and has assembly accuracy in different positions and directions When required, the assembly dimension chain should be supervised in different directions}
30. What are the methods to ensure assembly accuracy? How are the various methods applied?
{1. Interchange method; 2. Selection method; 3. Modification method; 4. Adjustment method}
31. The composition and function of machine tool fixtures?
{The machine tool fixture is a device for clamping the workpiece on the machine tool. Its function is to make the workpiece have a correct position relative to the machine tool and the tool, and keep this position unchanged during the processing. .The components are: 1. Positioning element or device. 2. Tool guiding element or device. 3. Clamping element or device. 4. Coupling element 5. Clamping body 6. Other elements or devices..
Main functions 1. Ensure processing quality 2. Improve production efficiency. 3. Expand the scope of machine tool technology 4. Reduce labor intensity of workers to ensure production safety.}
32. According to the scope of fixture use, how to classify machine tool fixtures?
{1. Universal fixture 2. Special fixture 3. Adjustable fixture and group fixture 4. Combination fixture and random fixture}
33. The workpiece is positioned on a plane. What are the commonly used positioning components? And analyze the elimination degree of freedom situation.
{The workpiece is positioned in a plane. Commonly used positioning elements are 1. Fixed support 2. Adjustable support 3. Self-aligning support 4. Auxiliary support}
34. The workpiece is positioned with a cylindrical hole. What are the commonly used positioning components? And analyze the elimination degree of freedom situation.
{The workpiece is positioned with a cylindrical hole. The commonly used positioning elements are 1 spindle 2. Locating pin}
35. What are the commonly used positioning components for the positioning of the outer circular surface of the workpiece? And analyze the elimination degree of freedom situation.
{The workpiece is positioned on the outer surface of the outer circle. The commonly used positioning elements are V-shaped blocks}
36. The workpiece is positioned with “two pins on one side”. How to design two pins?
{1. Determine the size and tolerance of the center distance between the two pins 2. Determine the diameter of the cylindrical pin and its tolerance 3. Determine the width diameter of the diamond pin and its tolerance.}
37. What are the two aspects of positioning error? What are the methods for calculating the positioning error?
{Two aspects of positioning error. 1. The positioning error caused by the inaccurate production of the positioning components on the workpiece positioning surface or the fixture is called the reference position error. 2. The positioning error caused by the misalignment of the workpiece process reference and the positioning reference is called the reference error Coincidence error}
38. Basic requirements for the design of workpiece clamping devices.
{1. The correct position obtained when the workpiece is positioned should be maintained during the clamping process. 2. The clamping force should be appropriate, and the clamping mechanism should be able to ensure that the workpiece does not loosen or vibrate during processing, and at the same time avoid the workpiece Inappropriate deformation and surface damage occur, the clamping mechanism should generally have a self-locking effect
3. The clamping device should be easy to operate, labor-saving and safe. 4. The complexity and automation of the clamping device should be adapted to the production batch and production method. Structural design should be simple, compact and use standardized components as much as possible}
39. What are the three elements for determining the clamping force? What are the principles for the selection of clamping force direction and action point?
{ The selection of the clamping force direction of the action points in the large and small directions should generally follow the following principles: 1. The action direction of the clamping force should be conducive to the accurate positioning of the workpiece without destroying the positioning. For this reason, the main clamping force is generally required to be directed vertically to the positioning surface. 2. The direction of the clamping force should be as consistent as possible with the direction of the workpiece with high rigidity, so as to reduce the clamping deformation of the workpiece. General principles for selection of force clamping force application point:
1. The action point of the clamping force should be directly on the supporting surface formed by the supporting element to ensure that the positioning of the workpiece is unchanged.
2. The action point of the clamping force should be in a position with better rigidity to reduce the clamping deformation of the workpiece. 3. The action point of the clamping force should be as close to the machined surface as possible to reduce the turning moment caused by the cutting force on the workpiece}
40. What are the commonly used clamping mechanisms? Focus on analyzing and mastering the wedge clamping mechanism.
{1. Wedge clamping structure 2. Spiral clamping structure 3. Eccentric clamping structure 4. Hinged clamping structure 5. Centering clamping structure 6. Linkage clamping structure}
41. How to classify according to the structural characteristics of drilling dies? How to classify according to the structural characteristics of drill sleeves? According to the specific connection method of the drill template and the clamp, what are the categories?
{Drill die according to common structural characteristics:
1. Fixed drill 2. Rotary drill 3. Flip drill 4. Cover plate drill 5. Structural features of spool drill
2. 1. Fixed drilling die 2. Replaceable drilling die 3. Quick change drilling die 4. The connection method of the special drilling die and drilling template to the clamp:
3. Fixed hinged, separated, suspended}
42. What are the characteristics of the machine tool clamp of the machining center?
{1. Functional simplification 2. Full positioning 3. Open structure 4. Quick readjustment
