1. What are the three methods of workpiece clamping?
{1. Clamping in the fixture; 2. Direct alignment clamping; 3. Scribing alignment clamping}2. What does the process system include? {Machine tool, workpiece, fixture, tool}3. What are the components of the machining process? {Roughing, semi-finishing, finishing, super-finishing}4. How are the benchmarks classified? {1. Design benchmark 2. Process benchmark: process, measurement, assembly, positioning: (original, additional): (rough benchmark, fine benchmark)}What does machining accuracy include? {1. Dimensional accuracy 2. Shape accuracy 3. Position accuracy}5. What does the original error that occurs during the machining process include? {Principle error·Positioning error·Adjustment error·Tool error·Jig error·Machine tool spindle rotation error·Machine tool guide rail guidance error·Machine tool transmission error·Process system force deformation·Process system heat deformation·Tool wear·Measurement error·Error caused by residual stress of workpiece·}6. What is the influence of process system stiffness on machining accuracy (machine tool deformation, workpiece deformation)? {1. Workpiece shape error caused by changes in the position of the cutting force action point 2. Machining error caused by changes in the size of the cutting force 3. Machining error caused by clamping force and gravity 4. The influence of transmission force and inertia force on machining accuracy}7. What are the contents of the guide error of the machine tool guideway and the spindle rotation error? {1. Guideway Mainly includes the relative displacement error between the tool and the workpiece in the error-sensitive direction caused by the guideway 2. Spindle Radial circular runout, axial circular runout, inclination swing}8. What is the "error reflection" phenomenon? What is the error reflection coefficient? What are the measures to reduce error reflection? {Due to the change in the error deformation of the process system, the blank error is partially 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 the transmission error of the machine tool drive chain? Measures to reduce the transmission error of the drive chain? {Error analysis: that is, using the angular error Δφ of the end element of the transmission chain to measure measures: 1. The fewer the number of transmission chain parts, the shorter the transmission chain, the smaller Δφ, and the higher the accuracy 2. The smaller the transmission ratio i, especially the small transmission ratio at the beginning and the end, 3. Since the error of the end part in the transmission part has the greatest impact, 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 variable system errors? Which errors are random errors
{System error: (constant system error variable system error) Random error Constant system error: processing principle error, manufacturing error of machine tools, tools, fixtures, processing system stress deformation caused by processing errors Variable system error: wear of props; thermal deformation error of tools, fixtures, machine tools, etc. before thermal equilibrium Random error: copy of blank error, positioning error, tightening error, multiple adjustment error, deformation error caused by residual stress }11. What are the ways to ensure and improve processing accuracy? {1. Error prevention technology: Rationally adopt advanced technology and equipment to directly reduce the original error, transfer the original error, average the original error, and homogenize the original error. 2. Error compensation technology: online detection, automatic grinding of pairs of parts, and actively control the error factors that play a decisive role.} 12. What does the geometric morphology of the machined surface include? {Geometric roughness, surface waviness, texture direction, surface defects} 13. What do the physical and chemical properties of the surface layer material include? {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 the cutting process? {Roughness value is determined by: the height of the cutting residual area. Main factors: tool tip radius, main rake angle, secondary rake angle, feed rate. Secondary factors: increase in cutting speed, appropriate selection of cutting fluid, appropriate increase in the rake angle of the tool, and improvement of the tool grinding quality.} 15. Try to analyze the factors that affect the surface roughness of the grinding process? {1. Geometric factors: the effect of grinding amount on surface roughness 2. The effect of grinding wheel grit and grinding wheel dressing on surface roughness 2. The effect of physical factors: plastic deformation of surface metal: grinding amount, selection of grinding wheel} 16. Try to analyze the factors that affect the cold work hardening of the cutting surface? {The effect of cutting amount, the effect of tool geometry, the effect of processing material properties} 17. What is grinding tempering burn? What is grinding quenching burn? What is grinding annealing burn? {Tempering: If the temperature of the grinding zone does not exceed the phase transition temperature of the quenched steel, but has exceeded the transformation temperature of the martensite, the martensite on the surface of the workpiece will be transformed into a tempered structure with lower hardness. Quenching: If the temperature of the grinding zone exceeds the phase transition temperature, coupled with the cooling effect of the coolant, the surface metal will show a secondary quenched martensite structure with a higher hardness than the original martensite; in its lower layer, a tempered structure with a lower hardness than the original tempered martensite appears due to slower cooling. Annealing: 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 show an annealed structure and the hardness of the surface metal will drop sharply.} 18. Prevention and control of machining vibration {Eliminate or weaken the conditions that produce machining vibration; improve the dynamic characteristics of the process system; improve the stability of the process system; use various vibration reduction devices} 19. Briefly describe the main differences and applications of machining process cards, process cards, and procedure cards. {Process card: Single-piece small batch production using ordinary processing methods Machining process card: Medium batch production Process card: Large batch production types require strict and meticulous organization}*20. Principles for selecting rough datums? Principles for selecting fine datums? {Rough datum: 1. The principle of ensuring mutual position requirements; 2. The principle of ensuring reasonable distribution of machining allowances on the machining surface; 3. The principle of facilitating workpiece clamping; 4. The principle that rough datums are generally not reused Fine datum: 1. The principle of datum coincidence; 2. The principle of unified datum; 3. The principle of mutual datum; 4. The principle of self-datum; 5. The principle of facilitating clamping }21. What are the principles for arranging the process sequence? {1. Process the datum surface first, then process other surfaces; 2. In half of the cases, process the surface first, then process the hole; 3. Process the main surface first, then the secondary surface; 4. Arrange the rough machining process first, then the fine machining process }
22. How to divide the processing stages? What are the benefits of dividing the processing stages?
{ Division of processing stages: 1. Roughing stage·Semi-finishing stage·Finishing stage·Precision finishing stage It can ensure that there is sufficient time to eliminate thermal deformation and eliminate residual stress caused by roughing, so as to improve the accuracy of subsequent processing. In addition, if defects are found in the blank during the roughing stage, it is not necessary to proceed to the next processing stage to avoid waste. In addition, equipment can be used reasonably, low-precision machine tools are used for roughing, and precision machine tools are used specifically for finishing to maintain the accuracy level of precision machine tools; human resources are arranged reasonably, and high-tech workers specialize in precision and ultra-precision processing, which is very important for ensuring product quality and improving process level. }23. What are the factors that affect process allowance? {1. The dimensional tolerance Ta of the previous process; 2. The surface roughness Ry and the depth of surface defects Ha generated by the previous process; 3. The spatial error left by the previous process}24. What does the composition of the labor time quota include? {T quota = T single piece time + t quasi-final time / n number of pieces} 25. What are the process approaches to improve productivity? {1. Shorten the basic time; 2. Reduce the overlap of auxiliary time and basic time; 3. Reduce the time to arrange the work site; 4. Reduce the preparation and termination time} 26. What are the main contents of the assembly process specification? {1. Analyze the product drawings, divide the assembly units, and determine the assembly method; 2. Draft the assembly sequence and divide the assembly process; 3. Calculate the assembly time quota; 4. Determine the assembly technical requirements, quality inspection methods and inspection tools for each process; 5. Determine the transportation method of the assembled 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 processability of the machine structure? {1. The machine structure should be able to be divided into independent assembly units; 2. Reduce repair and machining during assembly; 3. The machine structure should be easy to assemble and disassemble} 28. What does assembly accuracy generally include? {1. Mutual position accuracy; 2. Mutual motion accuracy; 3. Mutual matching accuracy} 29. What issues should be paid attention to when looking for assembly dimension chains? {1. The assembly dimension chain should be simplified as necessary; 2. The assembly dimension chain consists of "one piece and one link"; 3. The "directionality" of the assembly dimension chain. In the same assembly structure, when there are assembly accuracy requirements in different positions and directions, 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. Repair method; 4. Adjustment method} 31. The composition and function of machine tool fixtures? {Machine tool fixtures are a device for clamping workpieces on machine tools. Their 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 elements or devices. 2. Tool guide elements or devices. 3. Clamping elements or devices. 4. Connecting elements. 5. Clamp body. 6. Other elements or devices.. Main functions 1. Ensure processing quality 2. Improve production efficiency. 3. Expand the process range of machine tools 4. Reduce the labor intensity of workers to ensure production safety.} 32. According to the scope of use of fixtures, how to classify machine tool fixtures? {1. General fixture 2. Special fixture 3. Adjustable fixture and group fixture 4. Combined fixture and random fixture}33. The workpiece is positioned on a plane. What are the commonly used positioning elements? And analyze the elimination of degrees of freedom. {The workpiece is positioned on a plane. Common positioning elements are 1. Fixed support 2. Adjustable support 3. Self-positioning support 4. Auxiliary support}34. The workpiece is positioned on a cylindrical hole. What are the commonly used positioning elements? And analyze the elimination of degrees of freedom. {The workpiece is positioned on a cylindrical hole. Common positioning elements are 1 spindle 2. Positioning pin}35. The workpiece is positioned on an outer circular surface. What are the commonly used positioning elements? And analyze the elimination of degrees of freedom. {The workpiece is positioned on an outer circular surface. Common positioning elements are V-shaped blocks}36. The workpiece is positioned with "one side and two pins". How to design the two pins? {1. Determine the center distance size and tolerance of 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 two aspects does the positioning error include? What are the methods for calculating positioning errors?
{Two aspects of positioning error. 1. The positioning error caused by inaccurate manufacturing of the positioning surface of the workpiece or the positioning element on the fixture is called the reference position error. 2. The positioning error caused by the misalignment of the process reference and the positioning reference of the workpiece is called the reference misalignment 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 of appropriate size. The clamping mechanism should ensure that the workpiece does not loosen or vibrate during the processing process, while avoiding inappropriate deformation and surface damage to the workpiece. 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 degree of automation of the clamping device should be adapted to the production batch and production method. The structural design should strive to be simple and compact and use standardized components as much as possible.} 39. Three elements for determining the clamping force? What are the principles for selecting the direction and point of action of the clamping force? {Size Direction Action Point The selection of the direction of the clamping force should generally follow the following principles: 1. The direction of the clamping force should be conducive to the accurate positioning of the workpiece without destroying the positioning. For this reason, it is generally required that the main clamping force is perpendicular to the positioning surface. 2. The direction of the clamping force should be consistent with the direction of the workpiece's maximum rigidity as much as possible to reduce the clamping deformation of the workpiece. 3. The direction of the clamping force should be consistent with the cutting force and the gravity of the workpiece as much as possible to reduce the required clamping force. General principles for selecting the point of action of the clamping force: 1. The point of action of the clamping force should be directly opposite to the supporting surface formed by the supporting element to ensure that the positioning of the workpiece remains unchanged. 2. The point of action of the clamping force should be in a position with good rigidity to reduce the clamping deformation of the workpiece. 3. The point of action of the clamping force should be as close to the processing surface as possible to reduce the overturning torque 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. Angle wedge clamping structure 2. Screw clamping structure 3. Eccentric clamping structure 4. Hinge clamping structure 5. Centering clamping structure 6. Linkage clamping structure}41. How to classify according to the structural characteristics of the drill template? How to classify according to the structural characteristics of the drill sleeve? What are the categories according to the connection method between the drill template and the clamp? {Drill templates are classified according to their structural characteristics: 1. Fixed drill templates 2. Rotary drill templates 3. Flip drill templates 4. Cover plate drill templates 5. Sliding column drill templates Drill template structural characteristics classification: 2. 1. Fixed drill templates 2. Interchangeable drill templates 3. Quick change drill templates 4 Special drill templates The connection method between the drill template and the clamp: 3. Fixed hinged separate hanging}42. What are the characteristics of the machine tool clamps of the machining center? {1. Simplified functions 2. Complete positioning 3. Open structure 4. Quick readjustment}
