Vibration getting cuts alveolus heart the mechanism research of deflective error

Keywords: Axial Hole Deviation1 of 　 of Deep Hole of Vibration Drilling 　 .

Foreword aperture heart is deflective it is the technical difficult problem that avoids hard in deep aperture treatment [1] . As a result of all sorts of reasons, if arbor bearing is deflective, oriented,cover asymmetry of force of deflective, cutting to wait to all can make broach produces initiative and deflective amount, and this one-sided gradient will increase as what get aperture deepness and increase ceaselessly, bring about broach finally get into direction more and more deviate workpiece axis of rotation, serious when can make broach from be gotten by the sidewall of treatment spare parts, cause treatment accident. The measure of correct an error that although already had many at deep aperture using at present,machines [2, 3] , but the method with more application still is being gotten cut the according to deflective quantity size after finishing, with Kong Xin the line is the circle outside workpiece of fiducial and new turning, in order to achieve the goal of correct an error. But the scope of application of method of this kind of correct an error is finite, and cannot from go up at all eliminate deflective enlarge a phenomenon. The experiment studies with treatment practice makes clear, vibration getting is cut is a kind of new-style technique that can raise deep aperture to machine quality significantly [4] . Vibration getting is cut with common get cut distinction to depend on getting the opposite vibration that in cutting a course, makes through oscillatory device generation can accuse between broach and workpiece, thereby change getting cuts mechanism, rise auger cut quality. Vibration getting is cut can make deflective phenomenon improves Kong Xin apparently, many document undertook discussing to its action mechanism. Document [5] think, broach is high frequency and oscillatory " still turn the result " and " tigidity turns the result " integrated action can restrain bore effectively deflective, raise the linearity of bore thereby. But as a result of the broach in vibration of low frequency interval " still turn the result " and " tigidity turns the result " very weak, accordingly afore-mentioned theory have certain limitation. The article is in document [6] on research gain base, get cut pulse cutting character considering vibration, discussed vibration getting to cut down the immanent mechanism with alveolus deflective heart, cut an experiment to undertake test and verify to academic derivation result through vibration getting. 2.

Auger cut the mechanism with treatment aperture deflective heart to analyse 　 (1) is common get cut Kong Xin in the system of deep aperture treatment that deflective quantity shows 1 times in the graph, the initiative and deflective quantity of broach is deflective to Kong Xin having main effect, as a result of the existence of initiative and deflective quantity, broach axes photograph is deflective to arising at workpiece axis of rotation, and deflective quantity as auger increase and expand what cut deepness gradually, broach axes contrail also more and more be far from theory getting to cut axes. Undertake simplifying through cutting a course to getting, build auger cut get level mechanical model is shown 2 times like the graph. Graph 1 common get the heart that cut hole deflective sketch map pursues 2 auger cut get level mechanical model is set get the axial force when cutting to be P, radial load is R, below the action of these two kinds of force, a bit what get a needle to be Q to displacement quantity from the central deflection of broach, be in balance position in this bits. From this the differential equation with attainable deflective broach is the E in type -- the I of 　 of 　 of stretch model quantity of drill pipe material -- the sectional and inertial quadrature of drill pipe is set, arrange type (1) is gotten by ＝ of X of attrib border condition 0, y ＝ 0 reach X ＝ L, y ＝ - Q can get form (the solution of 2) is pair of type (3) both sides is begged guide by the graph 2 knowable, influence aperture heart is deflective is radial load R, attrib border condition era enters type (4) , have, r value generation returns form (when L of ＝ of 4) proper X, broach is into the deflective part that gets free end your, and type (6) spreads out so that be in (7) the negative sign that the purify in type shows deflective way, p carries outside be being become far when be less than Pc of buckling limit load, the initiative and deflective horn of broach can simplify for type (enter in 8) get deflective amount. Be in common auger in cutting treatment, as get those who cut deepness to increase, below the influence of initiative and deflective quantity, knife head increases gradually from the deviation of target axes (see a picture 1) . Set feed of cutting tool instantaneous to be Δ L, hole depth is Ln, criterion because this can be gotten,the deflective volume that aperture handles in aleatoric position is fall in the case with particular length of drill rod namely, common get cut Kong Xin deflective quantity and into get deflective amount Q0 and auger cut length Ln to concern. (2) deflective quantity discussion vibration gets the Kong Xin that vibration getting cuts cut Kong Xin is deflective quantity, need to cut a process to undertake an analysis to vibration getting above all. Cut in vibration getting in, after getting a needle to pound workpiece surface instantly go back, it suffers what action of transverse force instant arises to be out of shape after broach breaks away from workpiece restoration becomes straight, enter afresh again next auger. Accordingly, with common auger cut photograph comparing, deflective measure has the Kong Xin that vibration getting cuts two characteristics: ① is being entered get level, vibration getting is cut will common those who get the bit when cutting is one-time cut change to be pulse type for many times to be cut continuously, because get a tip,be pound workpiece again after deflection restores, got deflection quantity to get corrective, because this can make get a needle to get work with lesser deflection quantity, have Q0 namely brace up ＜ Q0 general. ② is being gotten cut level, as a result of the pulse action of broach, make of broach enter every time getting is not entering the base that gets error last time entirely aspirant travel, enter last time in what reduced however auger continue to get on deviation foundation cut. Set deviation to reduce coefficient to be δ (δ ＜ 1) , attainable vibration is gotten the Kong Xin that cuts deepness Ln part is being gotten when cutting deflective quantity contrasts to be the same as Likede type (10) and type (12) is knowable, when drilling the deep hole that cuts identical deepness with same broach, with common auger cut photograph comparing, vibration getting is cut getting the Kong Xin that cuts deepness to go up deflective quantity is reduced apparently, have Q namely brace up ＜ Q general. 3.

Auger cut treatment contrast to experiment the validity that for test and verify afore-mentioned theory analyse, right common auger cut and vibration getting cuts two kinds to get the Kong Xin that cuts treatment way deflective quantity undertook contrasting experimenting. The graph shows the vibration that designs for us 3 times to get cut treatment system. Oscillatory device uses mechanical compose of double prejudicial turbine, amplitude can be in 0 ～ 0.

Adjust continuously inside 5mm limits, dc engine rotate speed is controlled by direct current source, oscillatory frequency can be inside 100Hz through adjusting electric current of direct current source undertakes choosing, accordingly this vibration gets the amplitude that cuts a system to be able to satisfy different operating mode to fall and oscillatory frequency demand. Graph 3 vibration are gotten cut treatment system to experiment to be  with broach 7.

Deep aperture of bits of the platoon inside the small diameter DF of 9mm is gotten, l=630mm of cutting tool length, bit material is YT798; Test specimen is  the club of TC-4 titanium alloy of 14 × 130mm expects; The amplitude of oscillatory device is 0.

05mm, frequency is 90Hz; Feed is 0.

008mm/r, main shaft rotate speed is 1250r/min, fluid of the cutting in treatment chooses 5 ＃ mechanical oil, oil pressure 4MPa. Graph 4 for common auger cut the Kong Xin that cuts with vibration getting result of deflective quantity test is comparative. Can see from inside the graph, the Kong Xin that vibration getting cuts condition to fall is deflective the volume is minor, this agrees as a result with afore-mentioned theoretical analysises. The graph gets the Kong Xin that cuts way two kinds 4 deflective quantity is comparative 4. Conclusion vibration is gotten cut the cutting mechanism that changed bit, will common auger those who cut is one-time get continuously turn into periodic pulse wedge, vibration getting cuts existence cutting, restoration, again the dynamic process of cutting. With common auger cut photograph comparing, this one character that vibration getting cuts not only improved bit into get precision, and return slow down Kong Xin is deflective measure what go up in cutting deepness to accumulate speed, because this vibration is gotten,cut the Kong Xin in can reducing process of deep aperture cutting significantly deflective error. CNC Milling CNC Machining