Of method of turning of long and thin guide screw improve

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Summary: Of the old way of whorl of long and thin guide screw and its length than be 1 ∶ 30 when reaching its above, call long and thin guide screw. Because its are long way is older, in machining process, the whole machining complex such as machine tool, cutting tool bends extremely easily and oscillatory, treatment hind cannot obtain satisfactory exterior surface roughness and geometrical precision. Accordingly, the article discusses the method that guide screw turning improves slightness, in order to solve the turning difficult problem of long and thin guide screw. Keyword: Whorl of long and thin guide screw; Systematic tigidity; Machining; Of the old way of whorl of long and thin guide screw of geometrical precision 　 and its length than be 1 ∶ 30 when reaching its above, call long and thin guide screw. Guide screw is the component part that motion delivers in mechanical equipment, be turn into whirligig one of sharp movement spare partses, can transfer certain power not only, pass motion well and truly, and the linear graduation component that can make precision. Because its are long way is older, in machining process, the whole machining complex such as machine tool, cutting tool bends extremely easily and oscillatory, treatment hind cannot obtain satisfactory exterior surface roughness and geometrical precision, often still spend the reason such as abdomen of big, beat or circularity short of to cause workpiece to discard as useless as a result of warp, awl. In addition, because long and thin guide screw comes loose,hot property is differred, the heat in metal cutting in cutting process makes its generate quite big linear expansion, also make the job arises to be out of shape and bend. This shows, bar of turning fine filament manufactures efficiency not only very low, and quality assures not easily. Offer following means for this, in order to solve the turning difficult problem of long and thin guide screw. One, the machining complex tigidity that because long and thin guide screw machines a process,raises systematic tigidity is poorer and influence production efficiency and quality, because this must is opposite,machine tool, workpiece and cutting tool are made improve. The respect basically is placed to put forward from the outfit of workpiece here a few improve measure, the cutting condition that machines in order to obtain thick line of ameliorative fine filament, raise the tigidity of workpiece. Bearing of the tip after in placing workpiece to machine, be being used is installed in chuck, than need not hind top and when forming cantilever, workpiece tigidity rises a lot of. When turning slightness guide screw, used central wearing, make the distance between bearing shortened half, what can improve work is rigid. Use when following guide screw of slightness of tool carrier turning, shorten the distance between cutting action point and bearing dot, the tigidity of workpiece gets very big rise, cutting action is nodded and the distance between bearing dot is 5 ～ 10mm about. 2, use when following tool carrier to machine long and thin guide screw on lathe, will produce vibration easily, go against cutting; The 2 quality precision that will assure a spare parts not easily. The method that solves this difficult problem has two sides roughly: It is the cutting angle that improves cutting tool when cutting firstly, choose reasonable cutting dosage; It is to add secondly complementary, namely mount follows tool carrier, in order to eliminates vibration, in order to assure the quality of the spare parts and precision. Speed also can rise accordingly, feed also can increase, vibration is little, the spare parts flexibility that the car gives is little, improved productivity, also raised the treatment precision of the spare parts at the same time. 3, when the improvement of the method that hold clip is machining long and thin guide screw, the problem that exists generally is quality poor, efficiency is low. Had introduced to raise rigid method in front, but the influence as a result of heat in metal cutting, guide screw produces heat necessarily stretchy. And right now the distance between chuck and tip is fixed, work axial does not have adjustable leeway, make guide screw generation bends be out of shape. Be out of shape to decrease or eliminate this to plant, can use following methods: 1.

The steel wire of 10mm of Φ 4mm × is filled up between the every card claw of chuck and workpiece, sandwich length is 15 ～ 20mm. After filling up steel wire, make work with card line contact is become between claw, make there can be nominal and opposite campaign between workpiece and card claw thereby. Shun the job be blocked dead by card claw, have the effect of directional adjustment, reduce workpiece bend be out of shape. 2.

center of machine tool tailstock instead heads the stretch center of bedspring. Bounce size carries fast rate on the head to decide by the tip. Should work suffer generation of heat in metal cutting to expand and stretchy when, after driving a tip to compress bedspring to make a rod, move, avoided workpiece generation to bend be out of shape, assure to machine precision thereby. 3.

Use shrink neck law. In guide screw chuck a car goes to shrink cervical cent, shrink the diametical D=D/2 of cervical cent (the preform external diameter that D is guide screw) . As a result of guide screw shrink neck part diameter was reduced, its are flexible increase, as a result of,eliminate of guide screw itself bend and in chuck compulsive clip maintains the influence with wry line of lower shaft heart, also had the effect like versatile connect. 4, alignment slightness guide screw of the job expects bend, produce very big effect to adding labour union, fall in high speed circumgyrate especially, because leave the inertial action of mental efforts, aggravate of preform bend be out of shape, cause vibration, cause treatment difficulty, diminution of quality. Accordingly, the alignment job of long and thin guide screw in machining a process also is an indispensable content. Alignment assigns cold school and hot officer commonly two kinds, inspect craft to ask to be decided with preform circumstance. 1.

Hot school. Use hot alignment below two kinds of circumstances normally. It is undertake after heat treatment (guide screw undertakes moving pledging handling commonly) , be out of shape with eliminating what what produce in rough machining and heat treatment to bend. Its method is to working a heat treatment hind, should work a refrigeration arrive when certain level, examination workpiece is out of shape size, if exceed design technology requirement, need to undertake alignment, undertake on hand press commonly, school to craft requirement less than. Such alignment, workpiece is not easy spring back, assure the quality after working precision work. Method of another kind of hot school is undertake after semifinishing machining, its method is the workpiece alignment after semifinishing machining hind, immerse inside the oily pool of constant temperature, make the stress in workpiece alignment process gets elimination, workpiece interior organizes stability, after finish machining change not easily again go back (the condition before restoring alignment) , make the precision after work precision work is able to maintain for a long time. This method is used at precision to ask commonly taller guide screw. 2.

Cold school. Cold school also exists the following two kinds of circumstances: It is the alignment that expects in semifinished product of the guide screw before thick car, in order to assure the Che Yuan after thick car; It is whorl after thick car, in half fine vehicle or fine vehicle whorl advancement goes. Its action and hot alignment are identical, assure to machine success and the geometrical precision after raising guide screw to machine. The method of cold alignment has two kinds, the method that adopts normally is undertake on hand press, wool preform alignment is in overlay of hand press workbench two wait work of expensive bearing of V form iron. The two centers that semi-manufactured goods alignment uses hand press withstand the central aperture bearing of guide screw. This kind of method is the apogee that finds guide screw flexure with dial gauge, the pressure head that uses press presses apogee directly (when pressing semi-manufactured goods among need to fill up board) , make workpiece generation plasticity is out of shape, make change curvature control is inside craft requirement limits. The workpiece of alignment of this kind of method, after passing finish machining or heat treatment, workpiece can rebound likely go back, namely all or the condition before the part restores alignment, the precision after creating work precision work is lost, affect product quality. 5, the change of cutting means is in turning treatment, general direction taking a knife is from tailstock to direction of the head of a bed, common says to moving toward a knife. Turning needs to convert when long and thin bar take a knife reversely, the way fighting force that takes a knife makes workpiece suffers pull stress. Retrorse cutting makes workpiece gets drawing action, can eliminate brace up quiver, make cutting smooth, mix in the circle outside turning guide screw especially thick in cutting whorl working procedure, as a result of cutting muscularity, need to use retrorse cutting more, tailstock needs to assemble stretch vivid center. Be worth what carry is, when installing cutting tool, point of a knife should a bit line of center of prep above work 0.

1 ～ 0.

15mm, make the horn before the cutting of the cutting tool in cutting process increases, reduce cutting force, also reduce the cutting force compression to workpiece. In the meantime, in cutting process, point of a knife still is rising to hold the action of a workpiece in the palm, in order to offsets with tool carrier bearing piece is opposite the counterforce of workpiece, be equivalent to following the 4th bearing piece of tool carrier. Follow tool carrier to decrease bearing piece causes bearing piece with the attrition of workpiece to wear away badly, reduce workpiece temperature to lift, cool at the same time edge, noticing to adjust at any time with degree of tool carrier degree of tightness while, still need to undertake cool adequately and lubricating in cutting process, make cutting goes on wheels, assure the exterior surface roughness of the whorl after thick car. 6, when the axis of slightness of geometrical appearance turning of logical choice lathe tool, because workpiece is rigid poor, the vibration that appearance of cutting tool geometry produces to workpiece is very sensitive. If the geometrical appearance choice of lathe tool is undeserved, get favorable result impossibly also. The following basically considers when the choice: 1.

To reduce cutting force, those who reduce long and thin axis bend, the chief editor horn of lathe tool takes 75 ° ～ 93 ° . 2.

To reduce cutting force, should choose bigger before horn, take 15 ° ～ 30 ° . 3.

Should grind before lathe tool have R1.

5 ～ the chamfer breaking bits of 3, make cut bits to coil to be broken zigzag. 4.

Choose negative blade dip, take - 3 ° ～ - 10 ° , make cut bits to flow to work surface. On the other hand, lathe tool cuts work easily also, can reduce cutting force. 5.

Edge surface roughness wants tall, want to often keep sharp. 6.

To reduce radial cutting force, radius of point of a knife should be chosen lesserly (R ﹤ 0.

3mm) , the width that pours arris also should be chosen lesserly. 7, use double tool carrier to use cutting force and workpiece to suffer force to be out of shape to knife cutting quits principle, in using double tool carrier to be opposite, do not need to use central wearing namely, also do not need to use with tool carrier, the double knife that needs to adopt point of view of geometry of appropriate cutting tool only " to the knife " cutting, not only reduced workpiece to bend greatly be out of shape, and still can use big feed, raise cutting rate, have thick car, half fine vehicle or car of essence of life at the same time, shorten handling time, assure to machine quality. In around of the mount on lathe bed saddle two therein procrastinate board tool carrier, procrastinate in board guide screw also changes drive of left dextral whorl. Use from beginning to end radial of two lathe tool is installed relatively, lathe tool of half fine vehicle is being installed, lathe tool of essence of life is installed instead, take a knife along same axial direction, the left and right sides rotates guide screw is driven two therein procrastinate board tool carrier makes radial feed at the same time or retreat a knife, make two knives at the same time cutting, achieve the goal of disappear of cutting power balance. To make cutting equilibrium, the horn after lathe tool of essence of life needs to use 0 ° or small the horn after losing, increase the cutting power that place of lathe tool of essence of life produces, make with half fine vehicle (cutting surplus is large) the balance of cutting force photograph that produces. Radial cutting force is mutual and quits, kept clear of cutting of long and thin guide screw contains easy metabolic drawback. The knife that at the same time the after losing horn of lathe tool of essence of life forms faces workpiece to produce clash, the made function pressing light with rise particular, improved exterior quality, raised labor to manufacture efficiency. Long and thin guide screw grows way as a result of its bigger, medicinal powder hot performance is poor, bar of turning fine filament manufactures efficiency not only very low, and quality assures not easily. So, produce efficiency and working quality to raise labor, put forward to solve the method of difficult problem of turning slightness guide screw. But must be aimed at particular case and diverse demand alone or mix use, ability achieves anticipated result. CNC Milling CNC Machining