Inside the choice of the cutting tool in thread machining and tap

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Whorl is the method with the commonnest join of mechanical spare parts, and the fine that whorl aperture treatment often is in whole production process, once treatment is unqualified, discard as useless with respect to what can cause a part or more troublesome rework, because this its security to process raised taller requirement. Treatment whorl aperture has various cutting tool, commonly milling cutter of whorl lathe tool, tap, extruding tap, whorl is waited a moment. How to choose correct treatment cutting tool? The choice of cutting tool is the choice that machines a method actually, the cutting tool that place of method of every kinds of treatment uses has each different. To the treatment of whorl aperture, have a few kinds of kind commonly: Attack milling of tooth, turning, extrusion, whorl. The actor weakness that we understand all sorts of technique first below and use limitation, in actual production, we can machine methodological characteristic according to these, will analyse this to use which kinds of cutting tool to undertake machining from the angle of technology and economy. 1. Attacking a tooth to attack a tooth is a kind of method with the very wide application in whorl aperture treatment. It is OK the geometrical appearance of cutting tool of have the aid of decides whorl shape, when be being machined so need not special machine tool, in general accuracy machine tool, can use on product line private plane and machining center. The process that attack a tooth is tap is turning first undertake cutting, to whorl invert when bottom, leave work, cutting undertakes in very cramped space and will cut bits eduction. To different treatment condition, different treatment capable person is qualitative, chooses tap sort is different also. Use tap tap more in small diameter and big batch production. 2. Turning machines turning to machine whorl is use dislocation razor blade undertake turning is machined, produce the trigonometry whorl that middling uses, the appearance of cutting part of its whorl lathe tool should as sectional as the axial of whorl conform to closes. When turning, workpiece every turn, lathe tool must fore-and-aft shift a lead (only head whorl, lead = pitch) , ability treatment gives correct whorl. The method with car triangle commonly used whorl has the following 3 kinds: A.

Enter law car whorl continuously. When car whorl, after cutting examination workpiece, pitch to accord with a requirement via trying, radial and perpendicular at workpiece axes feed, repeat for many times, till whorl car is good. Form of tooth of method of this kind of turning is exacter. As a result of lathe tool two blade at the same time cutting and platoon bits not free, suffer muscularity, lathe tool is easy wear away, surface of whorl of cut of the meeting that cut bits. B.

Whorl of the inclined car that take a way. When workpiece pitch is more than 3mm, use the inclined car that take a way to machine whorl commonly, inclined taking a way is a side of form of tooth of whorl of lathe tool edge in radial feed while make axial feed, complete the treatment of whorl via taking a knife for many times, use the straight penetration of a cutting tool that take a way finally, assure the precision of the tooth body part of whorl. C.

Control feed standard. In common lathe, this kind of method is to use a horizontal stroke to procrastinate board the perpendicular feed of lathe tool of scale control whorl, with small procrastinate board the minim feed that scale control lathe tool controls. Be close to when whorl when be being cut, should use nut or dimension of whorl of whorl gauge examination and treatment precision are eligible. Operation of this kind of method is convenient, application is accordingly wider. Turning treatment whorl applies at the diameter commonly larger hole, and workpiece can be held by firm clip undertake gyral machining on lathe. 3. Extrusion machines extruding treatment to belong to the treatment that do not have bits. Like machining process and tap, extruding tap comes back beforehand bore, a material is squeezed in axial and radial, form outline of peculiar flute profile whorl thereby. Whorl extrusion applies to plasticity to be out of shape better stuff, material scope is less, of general requirement material rupture outspread rate is more than 7 % , and the greatest tensile strength is less than 1300N/mm. Apply in aluminium alloy treatment most, 4. The process of milling of whorl milling whorl, whorl milling cutter is to drop first commonly ministry of whorl hole bottom, the method that uses helix interpolation approachs work, edge whorl aperture rotates 360 degrees hind a pitch rises in before last of Z axis direction, leave work next. The torque when whorl milling cutter is machined is lesser, increased the security of process. It still has extensive applicability, can process all sorts of different data, and in pitch same situation falls, use a cutting tool to be able to machine an all sorts of whorl diameters or the whorl of tolerancepublic errand limits. Defect is: Requirement machine tool is the numerical control machine tool of 3 coordinate, additional foreign minister to tap, it is lower that its machine efficiency, cutting tool cost is higher also, apply to the treatment of aperture of big diameter whorl in small lot production so. We a moment ago were mentioned, tap is the treatment cutting tool that uses opening of the most extensive small diameter whorl at present, and attacking a tooth is more complex treatment process, the problem that because this machines a process,encounters is more also. Tap is common the problem includes to rupture, collapse blade, wear away etc. Rupturing basically is along tap whole cross section splits, the expression of collapse blade dies for cutting blade, and of tap wearing away is to show tap, front tooth uses time not to grow, its cutting blade is ground one part, make tooth dimension decrescent and cannot use. The tap of invalidation of these 3 kinds of means is far did not reach normal service life. After these problems appear in tap treatment, we can be emphasized will undertake an analysis from the following respects. 1. Machine tool problem checks a machine tool to whether be run normally, main shaft is jumpy whether to pass big, machine tool main shaft and bottom outlet are coaxial, machine program is waited a moment whether correctly. 2. The data strength of workpiece of workpiece material examination whether too tall, material quality is stable, have Cha of stomatic, incomplete to wait. 3. Diameter of whorl bottom outlet and diameter of bottom outlet of whorl of hole depth examination are correct, if bottom outlet diameter is too small, criterion workpiece of bring into contact with of ministry of the root when tap cutting, cause tap easily to break off. The diameter of whorl bottom outlet has line out in tap example, also perhaps can use (diameter of whorl of = of bottom outlet diameter - pitch) this formula reachs bottom outlet diameter. To extruding tap, the diameter of whorl bottom outlet and cutting tap are different, also can press formula (diameter of whorl of = of bottom outlet diameter - pitch / 2) cipher out probably bottom outlet diameter. To blind aperture, still need to consider the deepness of bottom outlet. Because tap front has tooth of a few cutting, the diameter of these cutting teeth is smaller, cannot be effective whorl, the dimension of the pointed part part of the deepness that considers cutting tooth even because of the deepness of this bottom outlet and tap front. Aborning, also had produced bottom outlet not quite deep, tap front comes up against hole bottom to cause the case that tap breaks off. 4. Whether to choose correct tap mention before the type, to different treatment condition, different treatment capable person is qualitative, chooses tap sort is different also. Machine a condition to what via differs two kinds with blind aperture above all, the cutting tap sort of the choice is different. The timber that cuts bits to growing is qualitative, for instance steel, below the circumstance of via, choose straight chamfer tap, cut bits to be discharged downward, below the circumstance of blind aperture, choose helix tap, cut bits upgrade platoon. Qualitative to the short material that cut bits, for instance cast-iron, scrap is drossy, can accommodate inside the chamfer that discharge bits, because this via and blind aperture are OK,machine with straight chamfer tap. Still have a kind of case, what it forms left tap coming back downward cutting bits is departure, this kind of tap applies to workpiece and tool to lean nearlier, discharge the circumstance with bits insufficient space. In production, we often also see, helix chamfer tap is used in the treatment of via, this is a kind of incorrect use method. Have 3 reason: One of, helix chamfer tap is to discharge bits up, to achieve this result, the structure of tap itself is more complex, rigid and bad, and the route that cuts bits to transmit is longer, appear easily in helix chamfer transmission process the circumstance that gets stuck, cause collapse blade or break off. Secondly, the cutting tooth number before two kinds of tap is different much. Helix chamfer tap is commonly 2 - 3 cutting tooth, and straight chamfer tap is 3 - 5 cutting tooth. The life of tap becomes direct ratio with a number of cutting tooth. Thirdly, helix chamfer tap is a few more expensive than price of straight chamfer tap, economy is bad. On the other hand, to cutting tap, the capable person with different treatment is qualitative, we should choose different chamfer model tap. There are all sorts of point of views on tap, for instance before horn, hind dip of horn, oriented horn, blade is waited a moment, the design of these angle is the character according to different material, cite a case, steel with cast-iron, as a result of steel cut bits to grow quite, of tap before horny design is a few bigger, and cast-iron scrap is drossy commonly, horn is compared before small, it is the horn before 0 ° even. Cutting tool company can be aimed at different workpiece capable person to give out character different commendation tap, to processing steel, the tap with the common qualitative capable person such as aluminium alloy, cast-iron, stainless steel, still may use different lubricious group to distinguish in petiole. 5. Parameter of cutting parameter cutting is very important, the tap of different type, different treatment condition, different workpiece capable person is qualitative, should choose different parameter. Get offline in same condition e.g. high-speed steel tap and hard alloy tap rate difference is very big, this rotate speed has certain limits, the linear velocity of high-speed steel tap is in commonly 20m/min less than (the feed of tap is fixed, it is pitch) , too fast too slow perhaps metropolis brings about tap invalidation, the cutting parameter with right choice can be in assure to manufacture efficiency while reach taller cutting tool life. 6. Cool and lubricate mention before us, tap is cutting undertakes in very cramped space and will cut bits eduction, in treatment the process can produce much heat, accordingly, it is very important to cool and lubricate. Compare big data to tenacity, can increase the concentration of cooling fluid, perhaps use oily cooling fluid. 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