The choice of cutting dosage

1. When the process designing of choice principle numerical control of cutting dosage, process designing personnel must determine the cutting dosage of every working procedure, include speed of quantity of penetration of a cutting tool of main shaft rotate speed, back, feed to wait, in inputting a program with the pattern that numerical control system sets. Cutting dosage machines a method to what differ, need to choose different cutting dosage. Choose cutting dosage reasonably, impact of efficiency of the exterior quality to the spare parts, precision, treatment is very big. This is in actual in master very hard also, want to rich practice experience ability determines right cutting dosage quite. The cutting dosage of the experience of the person that can depend on process designing only when numerical control process designing and cutting tool recommends a value preliminary and affirmatory, and final cutting dosage the basis of program of spare parts numerical control debug result and effective treatment circumstance to decide. The choice principle of cutting dosage is: With rising productivity is given priority to when rough machining, at the same time economy of give attention to two or morethings is mixed the consideration of finished cost; When semifinishing machining and finish machining, should at the same time the premise of efficiency of cutting of give attention to two or morethings and finished cost falls, assure the treatment quality of the spare parts. Notable is, cutting dosage (deepness of main shaft rotate speed, cutting and feed) it is an organic whole, the person that have 3 only suits each other, achieve the most reasonable match a cost, ability obtains first-rate cutting dosage. Answer to ask according to machining property, treatment when affirmatory cutting dosage, workpiece material reachs the specific requirement of the respect such as the dimension of cutting tool and material function, through consulting cutting manual combines experience to try to decide, when affirmatory cutting dosage besides abiding by general principle and method, return the impact that should consider the following factor: (1) the influence of cutting tool difference -- the difference of cutting tool quality that different tool manufacturer produces is very big, so cutting dosage needs to try to amend according to using cutting tool and spot experience actually. (2) the influence of machine tool character -- the rigid limitation of the power that cutting function gets numerical control machine tool and machine tool, must choose inside the range that machine tool manual sets. Because machine tool power is insufficient,avoid to produce frowsty car phenomenon, or the phenomenon of machine tool vibration with rigid and insufficient large generation, affect the treatment quality of the spare parts, precision and exterior surface roughness. (3) the influence of productivity of numerical control machine tool -- the man-hour cost of numerical control machine tool is higher, relative to character, the proportion that the loss cost place of cutting tool holds is inferior, answer to use tall cutting dosage as far as possible, will improve the productivity of numerical control machine tool through lowering cutting tool life appropriately. 2. The choice of cutting dosage (1) affirmatory back penetration of a cutting tool measures Ap (Mm) the stiffness of the machining complex that main basis machine tool, clamping apparatus, cutting tool and workpiece constitute the bulk that bears amount of penetration of a cutting tool will decide, below the condition that allows in systematic stiffness, to assure the mental allowance with semifinished product of least feed frequency purify, the basis is decided by the surplus of treatment spare parts statified cutting deepness, choose amount of larger back penetration of a cutting tool, in order to improve manufacturing efficiency. In CNC machining, to assure the treatment precision with essential part and exterior surface roughness, the proposal stays a few surplus (0.

2 ～ 0.

5mm) , in final precision work edge outline takes one knife. When rough machining, besides leaving necessary semifinishing machining and finish machining surplus, below the condition that allows in machining complex tigidity, answer to finish rough machining with least frequency. The deflection that leaves the surplus of finish machining to should be more than a spare parts and ensure integrality of spare parts surface. (2) N of rotate speed of affirmatory main shaft (R/min) the cutting speed VC that N of main shaft rotate speed basically allows according to cutting tool (M/min) affirmatory: Among them: VC -- cutting speed. D -- the diameter of spare parts or cutting tool (Mm) . Cutting speed VC and relationship of cutting tool durability are closer, as VC increase, cutting tool durability will drop quickly, the choice of reason VC basically depends on cutting tool durability. After N of main shaft rotate speed is affirmatory, the format that must control systematic place to set according to numerical control machine tool is written into numerical control program. In be operated actually, handlers is OK the basis machines a circumstance actually, the switch of fold of main shaft rotate speed that goes up through adjusting Control Panel of numerical control machine tool appropriately, will control the bulk of main shaft rotate speed, in order to determine rotate speed of first-rate main shaft. (3) feed or feed speed F (Mm/r, mm/min) the opposite displacement quantity that F of choice feed speed is the spare parts inside time of the unit when cutting and direction of feed of milling cutter edge, the unit is Mm/r or Mm/min. Feed or feed speed use F of feed function word on numerical control machine tool denotive, f is one of dosage of cutting of numerical control machine tool important parameter, the treatment precision of main basis spare parts and exterior surface roughness ask, and uses cutting tool and workpiece data will decide. The treatment precision demand of the spare parts is higher, when demand of exterior surface roughness is lower, the feed numerical value of the choice is less. Actual in, should consider integratedly machine tool, cutting tool, clamping apparatus and be reached by the tigidity of tigidity of change of the mechanical function of precision of treatment spare parts, material, curvature, structure, machining complex bits circumstance, choose appropriate feed career. Feed rate number is a special feed represents a means, namely the time that feed leads is reciprocal -- FRN (the abbreviate of Feed Rate Number) , to the feed of linear interpolation rate number is: The F in type -- feed (M/min) . L -- the treatment length of block, it is the effective space that place of work of cutting tool edge takes (Mm) . Enrolled feed leads several FRN in block, set the time T that carries out this block actually, the relation between them is: After F of feed of the make choice of when to program, the athletic rate of cutting tool center is fixed. When linear cutting, cutting is nodded (cutting tool and the point of tangency that machine the surface) athletic speed is to program when given feed. But when doing circular arc cutting, cutting nods actual feed and not be equal to the feed of the cutting tool center of the make choice of when to program. Use FRN process designing, when doing linear cutting, the length of because the distance of motion of cutting tool center and program are medium linear treatment often is different, the value of the FRN place correspondence that the feed with real reason and to program book is different also. When doing circular arc cutting, the feed angular velocity of cutting tool is fixed, the value of the FRN place correspondence that the feed that so cutting nods and process designing book is consistent. From this knowable, when a kind of numerical control device can use program of F work out already, when also can using program of FRN work out, do linear cutting to use program of feed F work out aptly, do what is appropriate to the occasion of circular arc cutting to use program of FRN work out. When feed F chooses in outline treatment, should notice to be in in outline corner " exceed Cheng " problem, be in especially corner when bigger and feed is bigger also, application is close to corner to be in proper slowdown, and carry gradually again afterwards in corner fast the method will assure to machine precision. When numerical control process designing, process designing personnel must determine the cutting dosage of every working procedure, write into the program with the form of the instruction. Cutting dosage includes quantity of penetration of a cutting tool of main shaft rotate speed, back and feed speed to wait. To different treatment method, need chooses different cutting dosage. To achieve the highest excision rate of highest productivity and unit time, in make sure the spare parts machines quality and premise of cutting tool durability to fall, answer to decide cutting parameter reasonably. Producing as numerical control machine tool actual medium wide application, numerical control process designing has become one of crucial issues in CNC Machining. In the work out process of numerical control program, want cutting tool of instant below interactive condition choice and affirmatory cutting dosage. Accordingly, process designing personnel must be familiar with the affirmatory principle of the selection method of cutting tool and cutting dosage, assure the treatment quality of the spare parts and treatment efficiency thereby, produce the advantage of numerical control machine tool adequately, raise the economic benefits of the enterprise and manufacturing level. CNC Milling