Machine tool crawl and vibration

  • Time:
  • Click:126
  • source:DELENO CNC Machining
There are a lot of apparent abnormal appearances in numerical control machine tool, but in having system of numerical control of a few economy, did not call the police however, although appear sometimes,call the police, the information that call the police makes clear also is not you what see abnormal phenomenon call the police. Machine tool occurrence crawl and vibration are a clear case. When the machine tool moves with low speed, machine tool workbench is to wriggling to move ahead; When the machine tool should move with high speed, appear shake. Crawl writing on some books about the machine tool: Because lubricate bad, and obstruction of the attrition when making machine tool workbench mobile increases. When electric machinery drive, workbench does not move ahead, make flexibility of generation of ball guide screw is out of shape, be out of shape the existence of energy lay aside of electric machinery on. Electromotor continues drive, when the stretch power that the energy place of keep in storage produces is more than static friction force, machine tool workbench wriggles ahead, ground of go round and round moves so, and the phenomenon that produced crawl. However the fact is not such, treat the condition with slideway lubricant face carefully, can concluding is not this problem. Machine tool crawl and oscillatory problem are the problem that attributes rate. Since be the problem of speed is about to seek speed link, the whole adjustment of the rate that we know a machine tool the process is finished by speed adjuster. Should emphasize particularly point out, the time of speed adjuster is invariable, namely constant of time of speed adjuster integral is with of millisecond plan, accordingly, the servo motion of whole machine tool is one transfers process, it is one adjusts process. The issue that always concerns with speed, can search speed adjuster only. Accordingly, problem of machine tool vibration also should search speed adjuster. Can from the following these places go searching speed adjuster breakdown: One is to give signal, one is feedback signal, another the itself that is speed adjuster. The first is the imitate that comes out to change speed adjuster to deliver via D ／ A by positional deviation tally it is VCMD, whether does this signal have oscillatory weight, can pass servo board to go up insert a foot (the servo of FANUC6 system board it is X18 foot) will have a look at it to whether be over there oscillatory. If it is the oscillatory signal that has a cycle, that without doubt machine tool vibration is correct, this one part does not have speed adjuster problem, however before class has a problem, go searching a question to converter of D ／ A or deviation tally. If we measure an outcome,do not have any oscillatory periodic weaveform. So the problem goes for certain in other two parts. We can observe measure fast the weaveform of the dynamo, be in as a result of the machine tool oscillatory, the rate that shows a machine tool is in intense oscillation, measure of course fast the dynamo feedbacks the weaveform that come back also is queasy certainly unceasingly. But we can see, measure fast what whether the rule appears in the weaveform that the dynamo feedbacks is big fall greatly, very confused phenomenon. At this moment, we are best whether is the speed that the oscillatory frequency that can measure a machine tool and electric machinery rotate put in an exact ratio to concern, the frequency of for example vibration is the fourfold frequency of electric machinery rotate speed. We are about to consider electric machinery or measure at this moment fast the problem that the dynamo has trouble. Because oscillatory frequency and electric machinery rotate speed become fixed rate, be about to check electromotor to whether have trouble above all, check its carbon brush, rectification child exterior state, and the circumstance of mechanical vibration, want to examine the lubricant case of ball bearing, whole this examination, but need not tear open debus to come entirely, it is OK to can observe all right through inspecting Guan Jin, bearing can listen to sound to check with ear. If do not have what problem, be about to check measure fast dynamo. Measure fast the dynamo is dc commonly. Measure fast the dynamo is dynamo of dc of magneto of a diminutive, its output voltage should direct ratio at rotate speed, outputting voltage and rotate speed namely is linear relation. It is certain to want rotate speed only, its output voltage weaveform ought to be linear, but because alveolar influence reachs rectification child the influence of inverting, go up point-blank in this adherent hand in variable tinily. For this, measure fast feedback circuit to went up to add filter wave circuitry, circuit of this filter wave weakens this to be added in the communication heft on voltage namely. Measure fast a defect that often appears in the dynamo is charcoal is brushed grind the charcoal pink stockpile that come down to be inside the chamfer between commutator segment, cause measure fast dynamo piece a short circuit, once appear,such problem cannot avoid this oscillatory problem. Because,this is this by the component of short circuit a little while above spur track, be in a little while below spur track, a little while as it happens is in inverting condition, these 3 kinds of circumstances measure the voltage of fast feedback with respect to what can appear to differ 3 kinds. Above when spur track, above because spur track became little a component, voltage wants necessarily small, and when it this component turned again below when spur track, the tension below is little also, at this moment no matter above spur track, still be in below in spur track, make the upright voltage of these two spur track drops necessarily, and the spur track that electric current of a balance has shed these two paralell connection, cause certain voltage drop again. Be in inverting when this component, it also is in as it happens short circuit, fluctuate at this moment two spur track do not have short circuit component, voltage is able to restore, and also do not have circumfluent. Such, with measure normally fast dynamo position is same. For this, the voltage below 3 kinds of different situations made a periodic change, when this voltage feedback arrives on adjuster, certainly will causes the output of adjuster to also make corresponding land, change periodicly. This was to say an element merely by short circuit. Particularly serious from time to tome commutator segment is given fill and level up by carbolic pink entirely, all short circuit, fluctuate with respect to more can serious voltage so. Feedback signal and give signal to adjuster it is identical. So, appeared the wave motion of feedback signal, cause speed adjuster necessarily turn over directional adjustment, cause the vibration of the machine tool so. When this kind of circumstance happening, handle very easily, should tear open electric machinery rear cover only below, show measure fast the commutate of the dynamo child. Need not do any disassembling at this moment, want to use acerb Gou Zi only, carefully every chamfer child tick off, use light of fine sand paper to tick off the burr that rise next, rectification piece exterior reoccupy is brushed without watery wine essence, it is OK to put charcoal to brush again. What should notice particularly here is to use acerb Gou Zi to tick off, do not come up against winding, because winding line is very fine, once touch,defeat cannot repair, change afresh only winding. Another must not be brushed with hydrous alcohol, did insulation resistance to drop so cannot undertake stoving, meet so protracted repair deadline. Besides these had discussed to cause oscillatory cause above us, returning a likelihood is the oscillation that the parameter of systematic itself causes. Well-known; System of a closed circuit is likely also because parameter set is bad, and cause systematic oscillation, but the enlarge that first-rate eliminates this oscillation method to reduce it namely is diploid, adjust in the system of FANUC RV1, go against clock direction roll, can see at this moment can ameliorate apparently instantly, but the scope as a result of RV1 adjustment potentiometer is less, move sometimes come nevertheless, can change short circuit club only, excise feedback resistance namely, the enlarge that reduces whole adjuster is diploid. After using these methods, still do not do eliminate vibration completely, it is invalid even, be about to consider pair of speed regulator board the canvass after change or be being changed everywhere undee. In this example, when occurrence crawl, electric machinery is in low speed, once raise speed to rise with respect to shake, at this moment electric current has appeared possibly to flow call the police. Producing this kind of account that call the police is machine tool workbench the face is restricted to feedback to follow quickly of signal change and change, must a very big acceleration just goes, this acceleration gives out by the torsion of electric machinery. The change of electric machinery torsion will answer this speed to give signal (it is feedback signal actually) change. Torsion is voltaic signal. Big torsion, big voltaic signal is caused, in the intense change that an electric current appeared in voltaic annulus, appeared to cross voltaic phenomenon thereby. Do not call the police when vibration, and when vibration is increased, appeared to cross electric current to call the police. From inside this example, we can sum up so: Positional problem goes seeking positional link, and rate problem goes seeking speed link. Alleged position annulus is the dimension issue that studies the spare parts is machined, the precision of the dimension of the spare parts should research positional link. Of course, the repetition of spare parts dimension precision still is concerned with datum mark, we discuss datum mark to return a problem even at the back. But in general, dimension problem, positional problem, ask the object of the consideration is positional annulus, the share that perhaps says to be concerned with positional annulus should be the main target of the consideration. The problem of speed is about to study speed annulus and the part that concern with speed annulus. Appearance of treatment spare parts had a problem, this is undertaken by a few axes interpolation is caused apparently. This is the pulse that NC countershaft undertakes allocate, if we think the pulse of NC countershaft allocates,be correct so (often such, be being encountered rarely is NC gave trouble, or interpolation software gave trouble and give the appearance with wrong shape of reveal one's true features) , so each axis affirms existence problem on the directive that implements NC in trustily. We can examine the issue that each axial servo unit consist. If we think what treatment has certain slope is linear, so the rate relationship that the speed of these two axes wants to press slope is given. Because numerical control machine tool is Electromechanical unifinication product, the element that machine tool of the influence side here works normally is very much, the processes appearance error matter that we ever had discussed range of exemple as above, besides the problem of electric field, we determine in what error momentum once discussed of numerical control machine tool in checking and accept, the geometrical appearance that this also is influence treatment a serious problem, the problem of this mechanical respect also with electric problem lump, this kind of circumstance very differentiate hard give which element after all how much does the proportion in this problem have. These relevant elements are to restrict us the main factor of rapid failure isolation. CNC Milling