Deep Kong Zuan cuts stability research and application

4 broach are gotten cut 40CrNiMo5 material, if the graph is shown 1 times,cutting torque changes, can divide for 5 phase. In oriented set guide below, each cutting blade is ordinal cut work, cutting torque increases quickly. At this moment, cutting join forces makes direct on broach piece clingy and oriented cover hole wall, have oriented effect, see a picture 1 medium OA paragraph. Broach is all after tooth cuts work, cutting torque is achieved the biggest. Because direct the difference of an axial position between point of a knife of the blade outside carrying ministry and broach, oriented piece still stay in oriented set inside, at this moment torque won't produce apparent change, see a picture 1 medium AB paragraph, this paragraph of distance also is called direct a lag quantity. Oriented piece after entering work, produce attrition, extruding with hole wall. At this moment torque can increase suddenly, as oriented piece enter entirely, broach centering action is strengthened, auger cut tend smooth, torque is reduced gradually, see a picture 1 medium BC paragraph. Broach already was being machined apparently stable and oriented, cutting torque does not have apparent wave motion, enter stability getting to cut level, see a picture 1 medium CD paragraph. When workpiece is gotten quickly to appear, central part produces plasticity to be out of shape, tine does not have cutting effect among broach center tine and part, tine is in among the tine outside having only and part excise leftover part, form consequently " cutting cap " . Right now energy instantaneous is released, cutting torque drops low tend 0, see a picture 1 medium DE paragraph. From this knowable, of broach into auger make cutting torque arises abruptly, of broach piece auger make cutting torque disappears abruptly, of its change extent big, enough affects workpiece to machine quality and broach durability, it is to get the main influencing factor that cuts stability. Oriented cover the influence with broach clearance to be gotten to guide broach correctly to enter, use normally on workpiece treatment goes out to guide aperture or be used oriented covered method, former use at sheet treatment, latter is used at batch production. Into get an error by broach and oriented set (guide aperture) the clearance between is caused, increase along with the accretion of axial force. Oriented if the graph is shown 2 times,cover the effect that gets an error to entering with broach clearance. Getting cut in the begining, radial load directs broach piece press guide to cover hole wall, as a result of both between have space, broach center produces deflection relative to workpiece centre of turning circle (2a) seeing a picture, the aperture that gets at this moment is less than broach diameter. Should direct piece begin to enter already machined Kong Shi, in the diameter slightly below little hole wall effect, will outside blade is squeezed outwards, make broach center opposite workpiece centre of turning circle to opposite way deflection (2b) seeing a picture, make bore diameter expands, and with oriented hole wall extruding chafes, make get cut torque to increase quickly, this one process and graph 1 medium BC paragraph answer relatively. Often right now broach happens suddenly shake, broach is incidental damaged. As oriented piece enter gradually, centering action is strengthened, treatment aperture also tends stable (2c) seeing a picture. Produce mouth of a horn in work entry point so, main aspects dimension is approximated oriented covered internal diameter, length is approximated direct a length. Gap is bigger, horn mouth is bigger also, into auger get easily slant, piece get deflective bigger, auger cut process vibration acuteness; Space is too little, incidental clip is gotten, cause cutting tool damaged. This shows, direct covering the gap with broach also is to get one of main influencing factor that cut stability. Axial force will increase the error when getting, influence getting cuts stability. According to material mechanical theory, the mechanical model that curves Jian Zhiliang with freely is cut to deep Kong Zuan get a process to undertake study. After building mechanical equation, can push derive axial force is opposite the enlarge coefficient X(u) of corner of deflection of the drill pipe when broach action, this coefficient is bigger, deflection corner is bigger also, namely X(u)=3(tgu-u)/uu=0.

In 5L(Fx/EI)½ type: L -- Fx of length of drill rod -- axial force E -- stretch model measures I -- the E in inertial rules form, I is constant, x(u) is concerned with L of length of drill rod and axial force Fx only, l, fx increases, x(u) increases accordingly. Entering when getting, axial force Fx from 0 increase the biggest, enlarge coefficient X(u) also increases ceaselessly, corner of drill pipe deflection also is magnified ceaselessly, cut entirely when cutting blade fashionable, corner is achieved the biggest. As a result of broach and oriented piece between have space, broach photograph tilts to happening at workpiece end panel, this is equivalent to be on oblique plane bore (2d) seeing a picture, into auger happen deflective, broach and drill pipe are circling roll of workpiece centre of turning circle, produce periodic vibration, make easily broach damaged, make workpiece surface produces helix groove, increase as what get aperture deepness and increase. Graph 2 directing the influence that covers the influence with broach clearance to get pointed height gets pointed height is to show the dot getting a tip of broach arrives direct the axial of a front is apart from, see a picture 3 medium H. The height that get a tip is greater, into get and give the time that get to grow more, do not get firmly surely cut time to also grow more. The rate of central tine cutting that because be located in,gets a tip is inferior, cutting muscularity, extruding attrition is serious, roll the bits, difficulty that break bits, centering, oriented poorer. Enter when getting " single-handed " , groggy, break tine or collapse blade easily. Piece when getting form not easily " cutting cap " , get a needle above all wear workpiece, the centering of the needle that oppose drill that loses hole bottom (4) seeing a picture, auger cut force abrupt overbalance, broach rock is abrupt aggravate, blade of very easy collapse (especially outside tine) . Because this gets pointed on any account,immediate impact is gotten cut durability of stability, broach and bore precision. 1.

The center ages (YG8) 2.

Intermediate smooth tine (YT798) 3.

Age outside (YT798) 4.

Oriented piece (YT798) 5.

Intermediate needle ages (YT798) 6.

Decrease brace up piece (YT798) pursues deep Kong Zuan of blade of the broken line inside 3 pointed tine 1.

Centering opposes drill 2.

Centering is annular protruding muscle pursues the appearance of 4 hole bottom directs the influence of a position is profound Kong Zuanli is used outside tine deputy blade and two direct decided circular proper motion to direct piece at 3 o'clock undertake cutting. Oriented piece must maintain from beginning to end with already machined hole wall contact, constant pressure exists, ability assures to machine the stability of the process. Current, in often using statics " stability " the concept serves as reasonable decorate direct the academic basis of a position. Stability is to show with what place should make an on-the-spot investigation that directs here piece as fulcrum, make be not make an on-the-spot investigation that directs a moment of force that controls Xiang Kongbi and make be not make an on-the-spot investigation that directs the ratio of a moment of force that breaks away from hole wall. A such broach have two stability, to the stability of whole bit, should both in the smallest stability S that regards this as broach, s value is greater, get it is better to cut stability, namely S ＞ 1 when, broach is in steady state; When S=1, broach is in critical condition; S ＜ 1 when, broach is in not steady state. 2 rise get the influence that each element narrates before the way that cuts stability is eliminated or be being reduced to be able to rise auger cut stability. The article gets a structure to improved a respect to undertake study from deep aperture only, designed broach of deep aperture of blade of the broken line inside a kind of pointed tine, detailed sees a picture 3. With common deep Kong Zuan photograph comparing basically undertook be improvemented below. Reduce the height that get a tip to reduce the height that get a tip, can pass increase offset, age the center inside blade of two broken line comes to blade wear implementation. Its characteristic is: Reduce the height that get a tip effectively (see a picture 3 get a needle mediumly to reduce H) by H ′ , shorten get and give the time that get. Enter when getting, the center ages and intermediate tine cuts work at the same time almost (see a picture 3 medium Δ H) , enter it is normal after getting to can be entered very quickly cutting position; Piece when getting, cutting cap is decreased thin, the knife on each tooth cuts force to disappear at the same time almost, rose effectively to enter get and give those who get a course to get cut stability. Additional, broken line blade still increased a center to the radiator of tine is accumulated and get pointed intensity inside. Change intermediate tine to be gotten to rise for pointed tine cut stability, we age intermediate tine design for the needle (3) seeing a picture. When cutting, intermediate tine forms annular protruding muscle in hole bottom, with inside broken line blade opposes drill in what hole bottom forms (the effect that 4) seeing a picture has to be cut to centering, stability getting at the same time. Increase decrease brace up piece common deep Kong Zuan uses two to direct mostly piece, with the tine outside broach deputy blade basically is decorated inside 180 ° , stability S ＞ 1, when cutting force when wave motion is not big, can assure to get cut process stability. But, because make,direct already machined aperture surface to have circularity error, and workpiece material is qualitative not all, enter especially get and go out auger, hard to avoid is being gotten vibration is caused in cutting a course, twist especially brace up, make broach directs with certain piece turn for fulcrum. This kind of circumstance, common deep Kong Zuan cannot be restrained. Accordingly, we are added in broach body back end decrease brace up piece, decorate upper part of outer tine edge to become the position of 90 ° to it, if pursue,3 are shown. When normal cutting, cutting join forces is pointed to two oriented piece between, make direct piece clingy already machined hole wall, have oriented effect, and decrease brace up piece be located in back end, blade is ground have awl to make with the clearance with already machined hole wall to have certain, not effective; Should get the overbalance that cut force to produce vibration, generation deviate directs when the displacement of a direction, decrease brace up piece ability is effective, can decrease brace up, disappear brace up, protect edge and the appearance precision that increase treatment opening. Equipment of test of condition of experiment of 3 experiments test and verify: C630 changes his costume or dress deep aperture drilling machine. Experiment broach: Ø58.

Deep aperture of blade of the broken line inside 4 pointed tine gets head and Ø58.

4 head of common deep Kong Zuan each 10. Workpiece material: 300HB of 40CrNiMo5 250HB ～ . Cutting dosage: N=230 R/min of main shaft rotate speed; Feed Vf=0.

03mm/r ～ 0.

15mm/r. Measure an instrument: SD375 dynamic analyzer, Y6D, recorder of function of appearance of meet an emergency of 3 A dynamic resistor, LZ3, measure force transducer and displacement sensor to wait. Experiment method measures force of cutting of two kinds of broach to be worth, see a table 1. Express contrast of 1 cutting force to try Vfmm/r of feed of Nr/min of test data rotate speed of new-style broach and common broach torque compare % new-style broach and force of common broach axial than %2300.

0385.

984.

32300.

0883.

576.

72300.

1578.

378.

61.

Common deep Kong Zuan 2.

Deep aperture of blade of the broken line inside pointed tine gets a picture curve of contrast of amplitude of 5 drill pipe measures situation of change of instantaneous axial force. Measure the amplitude that two kinds of broach are getting the drill pipe in cutting a course, comparative curve is shown 5 times like the graph. Measure two kinds of broach auger cut length. Measure the bore precision of two kinds of broach. Test result is analysed by the watch 1 can see, as the addition of feed, the axial force of two kinds of broach and torque increase accordingly. Deep Kong Zuan of blade of the broken line inside pointed tine is reduced more on average than force of axial of common deep Kong Zuan 20.

1% , torque is reduced on average 17.

4% , and increase as feed, force of new-style broach cutting adds relatively slow. The axial force that leaves according to function recorder records sudden change circumstance, when feed increases suddenly, the axial force of two kinds of broach all shows periodic change, but the wave peak value of new-style broach is less than common deep Kong Zuan from beginning to end, and fluctuant extent also is less than common deep Kong Zuan, this explains deep aperture of blade of the broken line inside pointed tine is gotten auger cut stability excel common deep Kong Zuan. The main reason that produces this kind of result is intermediate tine it is pointed age and have decrease brace up piece, enhanced centering action. Graph 5 it is two kinds of broach the comparative curve that gets amount of amplitude of the drill pipe in cutting a course. Dot of the A in the graph, B, C is a center respectively tine, oriented piece, decrease brace up piece auger fashionable the amplitude quantity of drill pipe. Apparent, as a result of blade of the broken line inside pointed tine deep Kong Zuan gets pointed height the low, tine intermediate is pointed tine, into get and whole get the vibration that cuts a course to all be less than common deep Kong Zuan, and after C is nodded, decrease namely brace up piece after entering work, broach still has to decrease brace up stable process, make get cut torque rapid and abate to normal level, and common deep Kong Zuan does not have this one process. Piece when getting, between D, E, common deep Kong Zuanzhen moves aggravate, amplitude increases, and new-style broach because difference of each knife tooth depth is little, get fully at the same time almost, and have again decrease brace up piece protection, can go out smoothly auger, drill pipe amplitude is very small. Cut distance length contrast to experiment according to two kinds of broach getting, because blade of the broken line inside pointed tine is deep it is good that Kong Zuan getting cuts stability, get on average cut distance length to amount to 16.

16m, prep above is common deep Kong Zuan is one times closer. Precision of bore of two kinds of broach is compared, deep aperture of blade of the broken line inside pointed tine gets bore circularity error to be controlled than small 3µm of common deep Kong Zuan, bore diameter error is small 0.

04mm, dimension precision can amount to class of IT8 of IT7 class ～ . Quality of surface of new-style broach bore is good, treatment surface is slick, without helix knife mark, exterior surface roughness is in Ra1.

0 ～ Ra3.

2 between. 4 conclusion deep aperture gets the durability that cuts stability to affect deep aperture broach directly and bore quality. Deep Kong Zuan cuts stability to basically suffer cutting force change to affect, still depend on next oriented set with broach clearance. The height that get a tip affects deep Kong Zuan to be cut directly get and give the stability that get. By get deep aperture of blade of the broken line inside the pointed tooth that cuts stability principle design, increase the stability that deep Kong Zuan cuts effectively. Via comparative experiment proof, auger cut smooth, broach durability and bore precision are tall, its design a thought to be able to regard deep henceforth Kong Zuan as the referenced foundation of reasonable design. CNC Milling CNC Machining