Surface of chamfer of gear single bond machines quality control to discuss

The characteristic that the case study broaching that blemish of quality of the surface in broaching process produces machines is treatment efficiency is tall, and can obtain stabler dimension precision, but also put in more blemish, producing the exterior quality flaw with common spot is surface roughness of keyway flank surface the cost is higher, local generation nick, serious when appear the phenomenon that gnaw an injury, the final quality that affects a product (see a picture 2) . Graph 2 　 basis is opposite for years the processing of spot problem, baconian summary undertakes labor to its reason, basically have the following: (1) blemish of existence of broaching craft oneself. Because bolt side is not by advocate cutting blade is cut, however by deputy cutting blade (namely tooth side edge) cut, the deputy cutting blade of its each tooth participates in the figuration of groovy side, can make groovy side appears consequently each tooth cuts the stripe that joins each other between mark (see a picture 3) . In addition, as a result of the horn after blade of its tooth deputy cutting is done not have, broaching is to be in actually squash and tear down metal, these cut bits and groovy wall to produce serious clash, the exterior surface roughness that brings about workpiece to obtain is worth taller. 　 of 　 of graph 3 (2) the hardness of workpiece material and state of heat treatment organization. Before helping single bond commonly, should make normalizing to material or move qualitative processing, acquire reasonable hardness and even metallographic organization. Via consulting relevant data, show work is too flexible (be less than 170HBW) and when tenacity is better, acquire good exterior quality hard. The material of the car gear part that our country uses at present is 20CrMnTi more, hardness of requirement semifinished product is 156 ～ 207HBW, and hardness of real semifinished product is centrally commonly between 160 ～ 185HBW. Material hardness is when 180 ～ 240HBW, can obtain more satisfactory surface surface roughness to be worth. Classics spot dogs for a long time test and verify, when the hardness of workpiece material is less than 160HBW, or below the condition with metallographic poorer organization, key side can generate scalelike mark, produce serious avulsion even circumstance. (3) cutting fluid. Of cutting fluid choose reach use unreasonable, without fixed deserve to compare, to cutting tool lubricant do not have apparent effect. The position with cutting pouring fluid is unreasonable, intensity also is one part reason not quite. (4) cutting tool blade is ground non-standard. Broach blade grinds technology and operation non-standard, main body raises an amount in tine now inhomogenous, figure of the chamfer that hold bit is incorrect, grinding speed passes fast or grinding amount is large wait for a respect, contain figure of department of bits chamfer root especially, create a bit not free, the card that cut bits is in a ministry, bring about keyway face cut, if did not clear in time, sequel cuts bits and remain to cut bits to occupy the slot that hold bit at the same time, cause broach to block sluggish, workpiece discards as useless, serious word brings about broach to discard as useless (see a picture 4) . Graph 4 　 　 (5) the operation of jockey is non-standard. The jockey in broaching process cannot keep clear of in time thoroughly inside the chamfer that hold bit cut bits, bring about groove to jam, keyway surface produces nick, cause the loss of broach even. Knock against of in use broach, place at will wait for behavior to be able to affect treatment quality. 2.

Broaching surface quality controls measure to be able to control keyway surface quality effectively to assure to be in treatment, consult through understanding effective treatment circumstance to reach to the spot for many times after relevant data, enacted relevant control measure: (1) the treatment quality that controls semifinished product strictly. Semifinished product is used forging craft of more than hot isothermal normalizing, strict control semifinished product machines quality, ask its metallographic microstructure should be thicker grain (5 class of 3 ～ ) austenite forms first eutectoid ferrite adds fritter shape pearlite (cementite piece Bao Yi burst) , and be apart from between eutectoid ferrite size and pearlite layer first should basic and identical. Ask the hardness control of semifinished product is in 165HBW above, but had better not exceed 180HBW, can cause a part because of exorbitant hardness the organization is unqualified, affect the integral performance of the spare parts. (2) make strict cutting tool blade grind a standard. ① builds complete blade to grind a standard, after the workpiece with requirement broach a certain quantity of broaching must blade is ground. ② is severe accuse cutting tool blade to grind a quantity, must not be more than every time 0.

1mm, and the blade that asks every age grinds a quantity even, measure in order to make sure the tine of tooth rises changeless. ③ grinds a process in blade in, improve round horn of emery wheel cutting, the bulk of the chamfer that hold bit of the cutting tool after blade is ground increases, improve quality of cutting tool surface, make sure the chamfer that hold bit is straight paragraph with circular arc Duan Guang slips conterminous, a bits that makes cutting tool can better, break bits, short-haired pelt of face of the knife after seasonable take out is pricked. ④ fills in according to the facts seriously blade grinds card, so that the problem is tracked. ⑤ blade is ground end, after should be being cleaned clean perpendicular hang condole to be on frame, lest because of self-prossessed and bend be out of shape. (3) requirement of normative jockey work. Before ① broaching, microscope cutting tool is sharp, touch injury or collapse blade to wait. Every pull ② a workpiece, should keep clear of in time thoroughly inside the chamfer that hold bit cut bits. ③ broaching after a certain number of workpiece, of cutting tool before knife face can arise tiny the tumour that accumulate bits, face of the knife after using tooth of fine oilstone edge is suitable to gently efface, must not injure cutting blade. ④ is forbidden in use and keeping put broach in broaching machine bed face or other on good thing, should avoid to collide with any good thing appearances, lest injure tooth. ⑤ appears when the workpiece that discovers broach broaching exterior surface roughness when the cost is high or when broaching satisfies formulary amount workpiece, must send blade in time to grind cutting tool. ⑥ requirement jockey has done a check and self check work in machining a process, discover a problem in time and feedback. (4) the use of cutting fluid. Cutting fluid, the proposal uses emulsion (25% emulsion of 20% ～ ointment, the others is water) , increase lubricant, and change regularly cutting fluid. Cutting should choose reasonably when broaching fluid, pouring the position and cooling means, reduce the attrition force between cutting tool and workpiece. Cutting fluid not just spray ages to the knife, best and outward appearance also has enough refrigeration. (5) broaching speed control. Cutting tool every time when blade grinds reuse, machine 20 first with must not exceeding the broaching speed of 2m/min greatly most, according to the circumstance of broaching, undertake machining with the regular rate of 3m/min again, must not change broaching speed at will. 3.

After epilogue is implementing above measure strictly, obtained right result, the case that surface of single bond chamfer presses injury and underfill badly not reappear, the exterior quality of key side also has before relatively very big change, quality of broaching of single bond surface gains very good control, achieved craft requirement. Unit: Treasure chicken Fashite author of gear limited company: Bandit exceeds boat CNC Milling