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Knife, buckle? Those faults in thread processing, see how the turner technician solves them!

  • Categories:Industry news
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  • Time of issue:2020-02-13 10:10
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(Summary description)Threadsarecontinuousprotrusionsandgrooveswiththesamecrosssectionformedalongthespirallineontheworkingsurfaceofacylinder.Whenthethreadisactuallyturned,duetovariousreasons,themovementrelationshipbetweenthespindleandthetoolisinacertainrange.Thereareproblemsinthelink,whichcausewasteproductswhenturningthreads,affectingnormalprocessingandproductionandeconomicbenefits.  First,thetrowel(trowel)failureanalysis:   原因Thereasonisthattheturningtoolisinstalledtoohighortoolow:theturningtoolisinstalledtoohightoreducetheactualrakeangleofthetool.Whentheknifeiseatentoacertaindepth,theflankoftheturningtoolisagainsttheworkpiece,increasingfriction.Force,eventhetopoftheworkpieceisbent,causingthephenomenonoftrowel;iftheturningtoolisinstalledtoolow,theactualrakeangleofthetoolisincreased,thechipsarenoteasytobedischarged,resultingintrowel. ⑵,theworkpieceorturningtoolisnotclampedfirmly:therigidityoftheworkpieceitselfcannotsupportthecuttingforceduringturning,whichresultsinexcessivedeflection,whichchangesthecenterheightoftheturningtoolandtheworkpiece(theworkpieceislifted),resultinginasuddenincreaseincuttingdepth,Thephenomenonofstabbingappears. (3)Theturningtoolisseverelyworn:theintensifiedfrictioncausesthecuttingforcetoincreaseandcausesthetrowel. ⑷,improperselectionoffeedmethodandfeedamount:whenthelargepitchisprocessed,thetwoedgesofthetoolareinvolvedincuttingatthesametime,andthefeedamountistoolarge,whichwillcausethecuttingforcetocausethecuttingphenomenon. Solution: ⑴Whensettingtheturningtool,usethetipofthetailstocktosettheknifeorusethemeasuringmethodtomakethetooltipandtheaxisoftheworkpieceequal.[Inroughturningandsemi-finishingturning,thepositionofthetooltipis1%higherthanthecenteroftheworkpiece.Disabout0.2~0.5mm,andD=thediameteroftheworkpiece.] 工件Theworkpieceandtoolmustbeclampedfirmly.Thetailstockcenter,centerframe,andtoolholdercanbeusedtoincreasetherigidityoftheworkpiece. (3)Correctandtimelysharpenthegeometricangleparametersofthetool.Asshownbelow: 左右Inthecaseoflarge-pitchmachining,theleft-rightcuttingmethodortheobliqueapproachmethodisused.Theturningtoolisasingle-edgedcuttingmethod,andthecuttingforceandfrictionforcearerelativelyreduced,soitisnoteasytoproduceaburrphenomenon.Inactualwork,aself-madeelastictoolbarisused(asshowninthefigure).Whenthecuttingforceexceedsacertainvalue,theturningtoolcanautomaticallyletthetoolmaintainthecuttingthicknessandeffectivelyavoidthephenomenonofcutting.   2.Randombucklefailureanalysis:Thereasonisthatwhenthescrewrotatesonerevolution,theworkpieceisnotrotatedbytheintegerrevolution.   Solution: ⑴Whentheratiobetweenthescrewpitchofthelathescrewandtheworkpiecepitchisnotanintegralmultiple:iftheopeningandclosingnutisusedwhenthetoolisretracted,andthesaddleisshakentothestartingposition,thentheturningoccurswhentheopeningandclosingnutisclosedagainThetipoftheknifeisnotinthespiralgroovethatwascutoutbythepreviousknife,sothatthebuckleappears.Thesolutionistousetheforwardandreverseturningmethodtoretractthetool,thatis,attheendofthefirststroke,withoutliftingtheopeningandclosingnut,afterthetooliswithdrawnintheradialdirection,themainshaftisreversed,andtheturningtoolisretractedinthelongitudinaldirection.Twostrokes,duringthisreciprocatingprocess,duetothetransmissionbetweenthespindle,thescrewandthetoolpost Theturningtoolhasnotbeenseparated,andtheturningtoolisalwaysintheoriginalspiralgroove,sotherewillbenoclutter. 对于Forthethreadoftheturninglathescrewpitchandtheworkpiecepitchratioisanintegralmultiple:theworkpieceandthescrewarerotating,afterliftingtheopeningandclosingnut,atleastoneturnofthescrewmustbeturnedbeforetheclosingnutcanbeclosedagain.Inthisway,whentheleadscrewisrotatedonce,theworkpieceisrotatedbyanintegermultiple,theturningtoolcanenterthespiralgrooveofthepreviousturningtool,andtherewillbenoclutter. 3.Thepitchisincorrect Failureanalysis:Thefulllengthorpartofthethreadisincorrect,thepitchisunevenonthefulllengthofthethread,orthebamboopatternappearsonthethread. Solution: ⑴Thelengthofthethreadisincorrect:thereasonistheimpropermatchingofthehangingwheelorthepositionofthefeedboxhandle.Youcanrecheckthepositionofthefeedboxhandleorcheckthehangingwheel. 局部,partialincorrect:Thereasonisduetothelocalerrorofthescrewpitchofthelathescrewitself(usuallycausedbywear),thescrewcanbereplacedorrepairedlocally. ⑶Theunevenpitchofthethreadovertheentirelengthofthethreadiscausedbytheaxialmovementoftheleadscrew,theaxialmovementofthemainshaft,theopeningandclosingnutoftheslideboxandthedifferentshaftofthescrew,resultinginpoormeshing,thedovetailguideoftheslideboxWearandtearcauseinstabilitywhentheopeningandclosingnutisclosed,andthegapbetweenthehangingwheelsistoolarge.Passthetest:Ifitiscausedbytheaxialmovementofthescrew,theadjustmentroundnutattheconnectionbetweenthelathescrewandthefeedboxcanbeadjustedtoeliminatetheaxialclearanceofthethrustballbearingattheconnection.Ifitiscausedbytheaxialmovementofthemainshaft,themainshaftadjustmentnutcanbeadjustedtoeliminatetheaxialclearanceoftherearthrustballbearing.Iftheopeningandclosingnutoftheslideboxandthescrewleadtodifferentsha

Knife, buckle? Those faults in thread processing, see how the turner technician solves them!

(Summary description)Threadsarecontinuousprotrusionsandgrooveswiththesamecrosssectionformedalongthespirallineontheworkingsurfaceofacylinder.Whenthethreadisactuallyturned,duetovariousreasons,themovementrelationshipbetweenthespindleandthetoolisinacertainrange.Thereareproblemsinthelink,whichcausewasteproductswhenturningthreads,affectingnormalprocessingandproductionandeconomicbenefits.  First,thetrowel(trowel)failureanalysis:   原因Thereasonisthattheturningtoolisinstalledtoohighortoolow:theturningtoolisinstalledtoohightoreducetheactualrakeangleofthetool.Whentheknifeiseatentoacertaindepth,theflankoftheturningtoolisagainsttheworkpiece,increasingfriction.Force,eventhetopoftheworkpieceisbent,causingthephenomenonoftrowel;iftheturningtoolisinstalledtoolow,theactualrakeangleofthetoolisincreased,thechipsarenoteasytobedischarged,resultingintrowel. ⑵,theworkpieceorturningtoolisnotclampedfirmly:therigidityoftheworkpieceitselfcannotsupportthecuttingforceduringturning,whichresultsinexcessivedeflection,whichchangesthecenterheightoftheturningtoolandtheworkpiece(theworkpieceislifted),resultinginasuddenincreaseincuttingdepth,Thephenomenonofstabbingappears. (3)Theturningtoolisseverelyworn:theintensifiedfrictioncausesthecuttingforcetoincreaseandcausesthetrowel. ⑷,improperselectionoffeedmethodandfeedamount:whenthelargepitchisprocessed,thetwoedgesofthetoolareinvolvedincuttingatthesametime,andthefeedamountistoolarge,whichwillcausethecuttingforcetocausethecuttingphenomenon. Solution: ⑴Whensettingtheturningtool,usethetipofthetailstocktosettheknifeorusethemeasuringmethodtomakethetooltipandtheaxisoftheworkpieceequal.[Inroughturningandsemi-finishingturning,thepositionofthetooltipis1%higherthanthecenteroftheworkpiece.Disabout0.2~0.5mm,andD=thediameteroftheworkpiece.] 工件Theworkpieceandtoolmustbeclampedfirmly.Thetailstockcenter,centerframe,andtoolholdercanbeusedtoincreasetherigidityoftheworkpiece. (3)Correctandtimelysharpenthegeometricangleparametersofthetool.Asshownbelow: 左右Inthecaseoflarge-pitchmachining,theleft-rightcuttingmethodortheobliqueapproachmethodisused.Theturningtoolisasingle-edgedcuttingmethod,andthecuttingforceandfrictionforcearerelativelyreduced,soitisnoteasytoproduceaburrphenomenon.Inactualwork,aself-madeelastictoolbarisused(asshowninthefigure).Whenthecuttingforceexceedsacertainvalue,theturningtoolcanautomaticallyletthetoolmaintainthecuttingthicknessandeffectivelyavoidthephenomenonofcutting.   2.Randombucklefailureanalysis:Thereasonisthatwhenthescrewrotatesonerevolution,theworkpieceisnotrotatedbytheintegerrevolution.   Solution: ⑴Whentheratiobetweenthescrewpitchofthelathescrewandtheworkpiecepitchisnotanintegralmultiple:iftheopeningandclosingnutisusedwhenthetoolisretracted,andthesaddleisshakentothestartingposition,thentheturningoccurswhentheopeningandclosingnutisclosedagainThetipoftheknifeisnotinthespiralgroovethatwascutoutbythepreviousknife,sothatthebuckleappears.Thesolutionistousetheforwardandreverseturningmethodtoretractthetool,thatis,attheendofthefirststroke,withoutliftingtheopeningandclosingnut,afterthetooliswithdrawnintheradialdirection,themainshaftisreversed,andtheturningtoolisretractedinthelongitudinaldirection.Twostrokes,duringthisreciprocatingprocess,duetothetransmissionbetweenthespindle,thescrewandthetoolpost Theturningtoolhasnotbeenseparated,andtheturningtoolisalwaysintheoriginalspiralgroove,sotherewillbenoclutter. 对于Forthethreadoftheturninglathescrewpitchandtheworkpiecepitchratioisanintegralmultiple:theworkpieceandthescrewarerotating,afterliftingtheopeningandclosingnut,atleastoneturnofthescrewmustbeturnedbeforetheclosingnutcanbeclosedagain.Inthisway,whentheleadscrewisrotatedonce,theworkpieceisrotatedbyanintegermultiple,theturningtoolcanenterthespiralgrooveofthepreviousturningtool,andtherewillbenoclutter. 3.Thepitchisincorrect Failureanalysis:Thefulllengthorpartofthethreadisincorrect,thepitchisunevenonthefulllengthofthethread,orthebamboopatternappearsonthethread. Solution: ⑴Thelengthofthethreadisincorrect:thereasonistheimpropermatchingofthehangingwheelorthepositionofthefeedboxhandle.Youcanrecheckthepositionofthefeedboxhandleorcheckthehangingwheel. 局部,partialincorrect:Thereasonisduetothelocalerrorofthescrewpitchofthelathescrewitself(usuallycausedbywear),thescrewcanbereplacedorrepairedlocally. ⑶Theunevenpitchofthethreadovertheentirelengthofthethreadiscausedbytheaxialmovementoftheleadscrew,theaxialmovementofthemainshaft,theopeningandclosingnutoftheslideboxandthedifferentshaftofthescrew,resultinginpoormeshing,thedovetailguideoftheslideboxWearandtearcauseinstabilitywhentheopeningandclosingnutisclosed,andthegapbetweenthehangingwheelsistoolarge.Passthetest:Ifitiscausedbytheaxialmovementofthescrew,theadjustmentroundnutattheconnectionbetweenthelathescrewandthefeedboxcanbeadjustedtoeliminatetheaxialclearanceofthethrustballbearingattheconnection.Ifitiscausedbytheaxialmovementofthemainshaft,themainshaftadjustmentnutcanbeadjustedtoeliminatetheaxialclearanceoftherearthrustballbearing.Iftheopeningandclosingnutoftheslideboxandthescrewleadtodifferentsha

  • Categories:Industry news
  • Author:
  • Origin:
  • Time of issue:2020-02-13 10:10
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Information
Threads are continuous protrusions and grooves with the same cross section formed along the spiral line on the working surface of a cylinder. When the thread is actually turned, due to various reasons, the movement relationship between the spindle and the tool is in a certain range. There are problems in the link, which cause waste products when turning threads, affecting normal processing and production and economic benefits.
 
 First, the trowel (trowel) failure analysis:
 
    原因 The reason is that the turning tool is installed too high or too low: the turning tool is installed too high to reduce the actual rake angle of the tool. When the knife is eaten to a certain depth, the flank of the turning tool is against the workpiece, increasing friction. Force, even the top of the workpiece is bent, causing the phenomenon of trowel; if the turning tool is installed too low, the actual rake angle of the tool is increased, the chips are not easy to be discharged, resulting in trowel.
 
⑵, the workpiece or turning tool is not clamped firmly: the rigidity of the workpiece itself cannot support the cutting force during turning, which results in excessive deflection, which changes the center height of the turning tool and the workpiece (the workpiece is lifted), resulting in a sudden increase in cutting depth , The phenomenon of stabbing appears.
 
(3) The turning tool is severely worn: the intensified friction causes the cutting force to increase and causes the trowel.
 
⑷, improper selection of feed method and feed amount: when the large pitch is processed, the two edges of the tool are involved in cutting at the same time, and the feed amount is too large, which will cause the cutting force to cause the cutting phenomenon.
 
Solution:
 
⑴ When setting the turning tool, use the tip of the tailstock to set the knife or use the measuring method to make the tool tip and the axis of the workpiece equal. [In rough turning and semi-finishing turning, the position of the tool tip is 1% higher than the center of the workpiece. D is about 0.2 ~ 0.5mm, and D = the diameter of the workpiece. ]
 
工件 The workpiece and tool must be clamped firmly. The tailstock center, center frame, and tool holder can be used to increase the rigidity of the workpiece.
 
(3) Correct and timely sharpen the geometric angle parameters of the tool. As shown below:
 
左右 In the case of large-pitch machining, the left-right cutting method or the oblique approach method is used. The turning tool is a single-edged cutting method, and the cutting force and friction force are relatively reduced, so it is not easy to produce a burr phenomenon. In actual work, a self-made elastic tool bar is used (as shown in the figure). When the cutting force exceeds a certain value, the turning tool can automatically let the tool maintain the cutting thickness and effectively avoid the phenomenon of cutting.
 
 
 
2. Random buckle failure analysis: The reason is that when the screw rotates one revolution, the workpiece is not rotated by the integer revolution.
 
   Solution:
 
⑴ When the ratio between the screw pitch of the lathe screw and the workpiece pitch is not an integral multiple: if the opening and closing nut is used when the tool is retracted, and the saddle is shaken to the starting position, then the turning occurs when the opening and closing nut is closed again The tip of the knife is not in the spiral groove that was cut out by the previous knife, so that the buckle appears. The solution is to use the forward and reverse turning method to retract the tool, that is, at the end of the first stroke, without lifting the opening and closing nut, after the tool is withdrawn in the radial direction, the main shaft is reversed, and the turning tool is retracted in the longitudinal direction. Two strokes, during this reciprocating process, due to the transmission between the spindle, the screw and the tool post
 
The turning tool has not been separated, and the turning tool is always in the original spiral groove, so there will be no clutter.
 
对于 For the thread of the turning lathe screw pitch and the workpiece pitch ratio is an integral multiple: the workpiece and the screw are rotating, after lifting the opening and closing nut, at least one turn of the screw must be turned before the closing nut can be closed again. In this way, when the lead screw is rotated once, the workpiece is rotated by an integer multiple, the turning tool can enter the spiral groove of the previous turning tool, and there will be no clutter.
 
3. The pitch is incorrect
 
Failure analysis: The full length or part of the thread is incorrect, the pitch is uneven on the full length of the thread, or the bamboo pattern appears on the thread.
 
Solution:
 
⑴ The length of the thread is incorrect: the reason is the improper matching of the hanging wheel or the position of the feed box handle. You can recheck the position of the feed box handle or check the hanging wheel.
 
局部, partial incorrect: The reason is due to the local error of the screw pitch of the lathe screw itself (usually caused by wear), the screw can be replaced or repaired locally.
 
⑶ The uneven pitch of the thread over the entire length of the thread is caused by the axial movement of the lead screw, the axial movement of the main shaft, the opening and closing nut of the slide box and the different shaft of the screw, resulting in poor meshing, the dovetail guide of the slide box Wear and tear cause instability when the opening and closing nut is closed, and the gap between the hanging wheels is too large. Pass the test: If it is caused by the axial movement of the screw, the adjustment round nut at the connection between the lathe screw and the feed box can be adjusted to eliminate the axial clearance of the thrust ball bearing at the connection. If it is caused by the axial movement of the main shaft, the main shaft adjustment nut can be adjusted to eliminate the axial clearance of the rear thrust ball bearing. If the opening and closing nut of the slide box and the screw lead to different shafts and cause poor meshing, you can trim the opening and closing nut and adjust the opening and closing nut clearance. If the dovetail guide rails are worn, dovetail guide rails and inserts can be formulated to achieve the correct fit requirements. If there is a gap between the hanging wheels
 
Large, can be used to readjust the gap between the hanging wheels.
 
竹, the occurrence of slubs: the reason is that the gear transmission from the main shaft to the lead screw is caused by periodic errors, such as the gear in the hanging wheel box, the gear in the feed box due to its own manufacturing error, or local wear, or gear Installing the eccentricity on the shaft causes the rotation center to be low, which causes the periodic non-uniformity of the screw rotation and the non-uniform periodicity of the tool movement, which leads to the appearance of bamboo veins. You can repair gears with errors or wear.
 
4.Incorrect diameter
 
Failure analysis: the reason is that the knife is too large, the dial is not accurate, and it is not caused by serious and timely measurement.
 
Solution: When finishing the car, check whether the dial is loose, make sure that the remaining amount of the car is appropriate, and sharpen the cutting edge of the car. Select the correct measurement method and reasonable measurement tools in time to carefully measure.
 
5.Rough thread surface
 
Failure analysis: The reason is that the cutting edge of the turning tool is not polished properly, the cutting fluid is not appropriate, the cutting speed and the workpiece material are appropriate, and the cutting process generates vibration.
 
The solution is: correct the grinding wheel or grind the tool with whetstone; choose the appropriate cutting speed and cutting fluid to avoid the generation of chipping; use a small feed to control the vertical axis of the chip to discharge and avoid damaging the processed surface; adjust The lathe bed saddle pressure plate and the gap between the inserts of the dovetail rails of the small and medium slides ensure the accuracy of the gaps between the guide rails and prevent vibration during cutting. Select a sufficiently rigid tool bar and the tool bar cannot extend too long.

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