Development of lathe tool of CBN rolling cut reachs his to machine quality research

The rolling cut lathe tool of razor blade of 5 ～ Ø23 CBN. Bit holds card with stretch card head, arbor is had adjustable before horn and blade dip, have sliding bearing and scroll bearing 2 kinds of cutter shaft. Cutting experiment makes clear, treatment quality basically suffers surface wave grain to spend an influence, use parameter of geometry of appropriate cutting rate, feed, cutting tool, reduce bit diameter and clearance of cutter shaft bearing to all can reduce ripple to spend. Jacket of rolling cut cutting tool has circular bit, razor blade of the circle in cutting process circles oneself axes to turn continuously. The roll when bit is by drive of appropriative electric machinery when, call cutting tool of drive type rolling cut (Driving Rotary Tool or DRT) ; The roll when bit is when by cutting motion is driven, call from rolling cut cutting tool (Self-propelled Rotary Tool or SPRT) . Must have certain blade inclination from the cutting blade of rolling cut cutting tool (E) , in order to produce the speed heft Vt with edge tangential edge, drive bit to turn (graph 1) . The main good point of SPRT is can great raise cutting tool durability, because this SPRT is appropriate at processing difficult treatment data, below this circumstance cutting tool durability can raise 30 ～ 100 times. Although SPRT already had application on industry, some designs already won patent, but by document tells us, the cutting tool data that uses on SPRT still is confined to high-speed steel and hard alloy, if CBN and PCD had be notted use at this one domain,exceed material of strong cutting tool. The article introduced the SPRT lathe tool of CBN razor blade. The author ever was planted to this quality of temperature of force of the rolling cut speed of cutting tool, cutting, cutting, treatment, cutting tool wears away waited for a respect to have initial test. The result makes clear, the SPRT lathe tool that holds CBN razor blade can use very high rate not only (treatment of 190 ～ 250m/min) quenchs steel (HRC50 ～ 55) , and the cutting tool durability that can keep very long (VB ＝ 0.

01 ～ 0.

02mm/h) . Consequently cutting tool wears away is not the main contradiction of CBN-SPRT in use any more. Study the result makes clear at the same time, treatment surface ripple spends the main factor that becomes an influence to machine quality, the treatment condition of impropriety can increase surface wave grain. The article was aimed at all sorts of elements to undertake to machining the influence of ripple more thorough discuss. 1 arbor designs a basis before research, 2 in rolling cut treatment main problems are bit rotates the vibration that the radial load place with the add greater sum of errors that causes causes. Accordingly, the tigidity of the rotational precision of cutter shaft bearing and arbor becomes SPRT arbor to design medium key. To the design of CBN-SPRT, because bit does not have the horn after Kong Mo, make to cutting tool so bring more issues, the designs about all sorts of rolling cut arbor article that heretofore place publishs did not involve this one case. The CBN-SPRT in the article should be used at the experiment, arbor still should have adjustable geometrical parameter, in order to discuss the effect of different geometry parameter to cutting sex. Graph 1 from graph of principle of job of rolling cut cutting tool D of the 2 horn before adjusting makes the razor blade after notting have produces the horn after cutting to consider above all sorts of requirements, designs arbor has following characteristic: When using bit of the horn after notting have, arbor still can install D of the horn before losing besides can install blade dip E, so that after knife face is mixed,machine the horn after be being formed between the surface, if pursue 2. Before the article was designed on the arbor of place introduction horn is worn and dip angle is worn, the horn before making and blade dip are successive and adjustable, see a picture 3. Horn is worn before and dip angle wearing can circle mutual and perpendicular dimensional axes roll, axes intersects in place of point of a knife, in order to make before horn and the adjustment with obliquitous blade do not affect height of point of a knife. For arbor suffer force to be out of shape decrease the smallest, arbor used compact structure in order to raise tigidity. (Side view of arbor of A) scroll bearing (side view of B) sliding bearing arbor (C) arbor front view 1.

Locknut 2.

Bearing core 3.

Bearing outer shroud 4.

Scroll body 5.

Ø12.

Razor blade of 7 ～ Ø23 6.

Pressing plate 7.

Horn is worn before 8.

Cutter shaft 9.

Bedspring blocks a head 10.

Ø9.

5 razor blade 11.

Arbor 12.

Dip angle wears a graph of razor blade of 3 use CBN two-way tilt rolling cut lathe tool pursues 4 surfaces ripple is spent detect experiment of turning of 2 experiments condition is in device C620-1 lathe is aspirant row, full test is dry cutting, particular test condition is as follows: Cutting tool and material of workpiece material cutting tool are BZN-6000CBN round razor blade, the diameter is Ø9 respectively.

5, Ø12.

7, Ø23. Workpiece material is 55 steel (GB699-88) , quench hardness is HRC50 ～ 55. Test specimen center gets the via that has 50mm diameter, appear a gender in order to raise temper by dipping in water, in whole and sectional on obtain even hardness. Ripple spends ripple of measurement unit surface to spend a definition to be grain of a kind of surface, the overlay on its has outline of exterior surface roughness. But the measurement technique that ripple did not offer to spend in the standard. Dial gauge was used to undertake metrical in this project. Dial gauge is fixed go up in knife stage, see a picture 4, move along workpiece surface, the peak cereal value inside 5mm sampling length spends data as ripple. Undertook repetition metrical reducing random error in the experiment, the average that measures in order to repeat regards an experiment as the result. Used in the 4 elements experiment of speed of dip of the horn before cutting parameter is being changed, blade, cutting, feed of Ø12.

The SPRT of 7 razor blade, parameter limits is: Before horny D=-10 ° , - 17 ° , - ° of E=-10 of dip of blade of 30 ° ; , - 14 ° , - 20 ° , - 28 ° , - V=100 of speed of cutting of 40 ° ; , 137, 187, 256, 350m/min; feed F=0.

1, 0.

14, 0.

2, 0.

28, 0.

4mm/r. Cutting deepness is 0.

05mm, keep changeless. Experimental data is used multivariate recursive method undertakes handling, recursive curve sees a picture 5. Bit diameter still is aimed at in research 9.

5, 12.

7, 23mm, of blade dip losing, of scroll, sliding bearing different undertook ripple spends an experiment, experimental result sees a picture 6. (Side view of arbor of A) scroll bearing (side view of B) sliding bearing arbor pursues angle of 5 cutting tool and cutting dosage spend an influence to ripple (arbor of A) scroll bearing, Ø23 razor blade (arbor of B) scroll bearing, Ø12.

7 razor blade (C) sliding bearing arbor, Ø9.

5 razor blade pursue direction of 6 blade dip and bearing structure spend an influence to ripple 3 analysises discuss to be seen by graph 5(a) , the larger part before losing makes ripple is spent increase. Generally speaking, the horn before losing adds an ambassador to get cutting force to increase, and increscent cutting power. Especially radial load, cause vibration easily, produce ripple thereby. Reduce the role before losing, cutting force is reduced subsequently. But to notting have hind horny razor blade, right now hind horn also is reduced at the same time. Horn crosses the attrition between face of hour of the knife after meeting aggravate and layer of treatment surface spring back after, make cutting force increases instead. Because this is chosen only proper before the ripple with horny gift inferior generation. Feed is bigger, ripple is spent bigger. The influence that cutting speed and blade dip spend to ripple sees graph 5(b) . The concern between rolling cut speed, cutting speed and blade dip can indicate by next type (refer to a graph to 1) Vt=vsine(1) raises cutting rate so or increase blade dip to be able to make rolling cut rate increases. Of rolling cut speed add an ambassador to must increase from mental efforts, reduced the smooth stability of cutting process, ripple is spent become poor subsequently. But see by graph 5(b) , reduce cutting speed and blade dip to cannot improve exterior quality likewise at the same time. Theoretic tell, no matter how V and E are small metropolis drive razor blade is rotational (1) seeing pattern, but actual condition is not such, because attrition exists in bearing, compare Xiaoshi when cutting speed and blade dip so, bit produces successive rolling cut very hard to move. Choose appropriate cutting rate and blade dip only so, ability makes bit turns equably, produce even treatment appearance thereby. Because cutting parameter is right the effect tendency that ripple spends is more complex, maths was used to optimize in research will seek optimal cutting condition. The mathematical model that in optimizing, uses analyses the experience formula of earning for regression namely. The basis optimizes computation, to using scroll bearing and Ø12.

The SPRT of 7 razor blade, when D=-12 ° , e= -13 ° , v=256m/min, f=0.

The ripple that gets when 14 Mm/r is spent the smallest. Discovery is returned in the experiment, below similar cutting requirement, should secure cutter shaft after making bit stops roll, can reduce greatly eliminate vibration completely even, make ripple is spent thereby reduce to 2 ～ 3µm. This proves further, vibration and ripple are concerned with the roll of bit. As a result of cutter shaft prejudicial with bearing clearance, can make cutting deepness changes, cause cutting force to fluctuate, produced vibration thereby. According to astral Tie Tailang discuss, when vibration be by external periodic displacement interference is aroused, when undertaking continuously with the form of self excited vibration, contain in this kind of vibration force vibration and self excited vibration, call mix model flutter. Usually, the treatment ripple that oscillatory place produces often forms the form of Zun Xuan, dextrorotation or straight grain. But the ripple that SPRT place produces is shown sometimes distributing randomly. Cutting process is relatively right now smooth, on cutting tool and workpiece the feeling is less than apparent vibration. This appears to make clear, displacement is disturbed and merely cycle can't cause vibration, if other a few parameter, suffer the dissatisfaction such as character of tigidity of frequency of power volume, interference, system, damp, natural frequency for example sufficient certain condition, vibration won't go down continuously. Because the roll of cutting tool is prejudicial,right now treatment ripple is merely cause. According to experimental record, right now ripple is spent inferior, can achieve 3µm. The rolling cut arbor that uses in the article is on structure and precision still very not ideal, if the course is farther perfect, acquire better treatment quality likely. To will improve the design of cutting tool henceforth, the influence that waits for an element to be spent to surface wave grain in the light of structure of direction of dip of bit diameter, blade, bearing undertook study. On the foundation of many observation data, pursue with histogram 6 conveyed experimental result. The cross axle in the graph states ripple spends a worth, x-axis expresses observation frequency. By the graph 6 visible, bit diameter is smaller, the ripple that produces is spent lower. As a result of,this is the accretion as bit diameter, average tool cutting edge angle is reduced, this will change the size of cutting force and way, make radial load (Fy) increases. This one analysis gets confirming in the experiment that measure power, the cutting power that produces of the cutting tool place of Ø3mm razor blade is outfit Ø12.

3 times of the cutting tool of 7mm razor blade. Affecting another when ripple spends main factor is bearing structure. The cutting tool of bearing of scroll of exterior quality prep above that treatment of sliding bearing cutting tool gives. The bearing of scroll of damp character excel that the reason may be sliding bearing; Sliding bearing structure is simpler at the same time, the ingredient that produces an error is less. From the graph 6 in still can see, for the cutting tool to having sliding bearing, bearing space is less, treatment quality is better. Because this can think, of the SPRT of sliding bearing of small diameter razor blade, little space, produce better treatment quality more easily. The CBN-SPRT that 4 conclusion place develops used flexibility to block head periphery to fit the pattern of card. To avoid cutting tool workpiece is interfered and drive razor blade turns, used adjustable before horn and blade dip. Surface wave grain is spent main by the roll of cutting tool prejudicial cause with vibration, oscillatory by force vibration and composition of self excited vibration. Too big or too small before horn metropolis aggravate vibration, increase ripple to spend. Rolling cut rotate speed is exorbitant too low also can make cutting process stability is reduced, increase ripple. To containing scroll bearing is mixed Ø12.

The SPRT of 7 razor blade, when D=-12 ° , e=-13 ° , v=256m/min, f=0.

The ripple that gets when 14mm/r is spent the smallest. Of the SPRT of sliding bearing of small diameter razor blade, little space, produce better treatment quality more easily. CNC Milling