The characteristic of straight chamfer broach and application

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  • source:NEHMER CNC Machining
About " helix chamfer broach cannot be replaced " traditional idea is being overturned by the treatment efficiency place of straight chamfer broach nowadays. In certain treatment circumstance, straight chamfer is gotten making more much better than twist drill cutting tool choice. Contemporary straight chamfer gets " precursory " it is mould broach (Die Drills) , dimension of this kind of broach is short, rigid good, get a needle to bear fruit, suit to be gotten with inferior main shaft rotate speed and minor feed rate cut material of treatment hard steel, its high strenth and tall tigidity make its can machine the opening that gives linearity and circularity all fine. Mould broach can obtain good treatment result, because design the treatment that is aimed at when broach,be material is the metal that generation weak point cuts bits normally. In the treatment application of straight chamfer broach, the control that cut bits remains a crucial problem. The ability when straight chamfer gets the data that processing those to won't produce long cirrus shape to cut bits only achieves optimal result, these material include cast-iron, pulverous alloy (P/M) , in - Gao Gui content (6 % or taller) silicon aluminium alloy. But, carry the progress of technology and design of appearance of cutting tool geometry as machine tool technology, cooling fluid, the treatment that straight chamfer gets applies limits to expanding ceaselessly. Traditional thinking pattern thinks the helix chamfer of broach to platoon bits it is indispensable, straight chamfer is gotten can use at be being mixed in aluminium only cast-iron on auger cut hole depth to be 2D ~ 3D (D is bore diameter) shallow aperture. But the high-pressured refrigeration system that develops nowadays and rotate speed of higher machine tool main shaft, make use inside cooling straight chamfer gets break bits and platoon bits function to rise greatly. In the treatment occasion with appropriate condition, straight chamfer broach can be shown far the favorable treatment function of broach of excel helix chamfer. The advantage of straight chamfer broach is to be able to machine the aperture with a circularity and taller linearity, and its cutting rate is rapidder than standard cobalt or high-speed steel broach. For example, with the diameter 0.

394 ″ (φ 10mm) Guhring RT150GG straight chamfer is gotten replace twist drill to machine aluminium when, the cutting speed of twist drill is 50sfm (15m/min) , feed is 0.

005ipr (0.

127mm/r) ; And the cutting rate that straight chamfer gets can amount to 800sfm (245m/min) , feed is amounted to 0.

007ipr (0.

178mm/r) . Straight chamfer gets a 1/10 that is twist drill only with cutting time. Straight chamfer gets the partial account that can improve treatment efficiency significantly is the basic design that is based on broach -- straight chamfer is the eduction that cut bits a direct channel was offerred outside aperture. But, lack as a result of the cutting blade of straight chamfer broach before horn, mix because of an its bits bits ability is very poor, when the stuff with the gender is extended better in treatment especially such. Cutting speed (especially enough high cutting rate) it is another ingredient that uses straight chamfer successfully to get. Cutting rate is rapidder, those who form cut bits smaller. Straight chamfer is gotten is higher feed rate does not achieve tall productivity does not achieve through faster main shaft rotate speed. A lot of get high-poweredly, high into the broach of fried dough twist of rate to have on cutting blade comparative to pour arris greatly, the feed that this asks broach enters the job should exceed the measure pouring arris of cutting blade, workpiece material undertakes cutting and making cutting blade can is opposite thereby is not elbow only it. To certain treatment application is reached by treatment material, the cutting blade of twist drill pours arris working position is good, and normally the cutting rate that the feed that with prep above straight chamfer gets is led and gets under straight chamfer undertakes these twist drill getting cutting. With company of car manufacturer Saturn auger cut treatment to be exemple. This company place is used before with broach about 500sfm (150m/min) cutting speed undertakes machining. They decide to do cutting to experiment later, want to decide these broach can undertake machining with much higher rotate speed after all. As a result they discover, after rotate speed rises, cutting tool life is lengthened, treatment cycle shortens, the efficiency that discharge bits rises. Use not when broach of coating whole hard alloy is machined, cutting speed can achieve 1000sfm (300m/min) , at the same time the quality with aperture all has cutting tool life to rise significantly. Through using the cooling fluid pressure of reasonable combination and cutting rate, straight chamfer is gotten also can machine those is not effectively inevitable generation is short the workpiece material that cuts bits. For example, get treatment with straight chamfer 1144 be able to bear or endure the effect of stress steel is first-rate, break bits successful and cut bits petty, also did not form the tumour that accumulate bits. Treatment place is H with broach.



Broach of straight chamfer of the refrigeration inside the 294-0500 blame coating of Precision company (diametical φ 5mm) , bore deepness is 48mm, cutting speed is 185sfm (63m/min) , feed is 0.

003ipr (0.

076mm/r) , cooling fluid pressure is 1500psi. The content of manganese of the vulcanization in 1144 alloy is higher, be helpful for breaking bits. But should process this kind of data successfully, need uses very high cooling fluid pressure (experience makes clear, cooling fluid pressure should be in 600psi above, had better use 1000psi, 1200psi or higher pressure) . Get to straight chamfer, besides the control that cut bits, the tumour that accumulate bits becomes an issue possibly also. Because be wanted to pass cutting blade from straight chamfer gets central eduction by the workpiece material of excision,this is, be pushed to broach get a tip. Avoiding one of methods that produce the tumor that accumulate bits is use surface flowing, bright and clean degree of tall broach; Use coating broach also conduces to prevent to produce the tumor that accumulate bits, if be used extensively at the 2 vulcanization molybdenum of aluminous treatment (MoS2) coating is had with special fluorine dragon (Teflon) similar character, produce felt not easily with other material, the treatment situation that prevents to produce the tumor that accumulate bits in need uses effect of broach of this kind of coating admirable. The structure getting a tip that straight chamfer gets makes its can be in of every straight chamfer outside grind along place blade give 2 first flank, because broach and workpiece have 4 contacts to nod, broach is more stable in treatment, can raise treatment precision thereby. The big vertex angle that straight chamfer broach uses also conduces to improvement its machine function. For example, h.



The broach of mark collimation chamfer of Precision company uses 140 ° vertex angle, be similar to a detached type to get a tip, this kind of structure is very OK small elbow force gets Kong Zhong. In addition, big vertex angle still can ensure the whole diameter of broach and workpiece material are fast joint, make broach " sideslip " the likelihood falls to the smallest. In a lot of treatment the circumstance falls, the oriented broach that had better be more than vertex angle of broach of hard alloy straight chamfer with its vertex angle first (the center is gotten) treatment gives an initiative opening (beforehand aperture) , such, the center getting a tip that can assure to add bit of man-hour straight chamfer formally (horizontal blade) enter above all beforehand aperture, blade of bigger hard alloy cutting is contacted with workpiece above all and cause collapse blade in order to avoid because of brittleness. Using straight chamfer to get another strategy of treatment is to beginning to get aperture decides simply first before cutting, because even if the workpiece surface that has machined too is put possibly also in blemish, handlers needs to be contacted with broach only beforehand aperture in order to determine its position. Want to contact workpiece above all by broach horizontal blade only, broach won't " sideslip " , fixed position aperture can arrive with rising similar get covered action. With 3 kinds different broach machines the linearity of the aperture that φ 10mm Kong Shi measures to make clear on cast-iron material: The cutting rate that broach of chamfer of high-speed steel helix uses is 98sfm (30m/min) , feed is 7.

66ipm (195mm/min) , use exterior and cooling means, the treatment quality of aperture reachs IT12 level; The cutting rate that broach of chamfer of helix of integral hard alloy uses is 295sfm (90m/min) , feed is 34.

5ipm (876mm/min) , use cooling fluid pressure to be 440psi/2.

Of 4-gpm inside cooling means, the treatment quality of aperture reachs IT9 level; The cutting rate that straight chamfer broach uses is 425sfm (130m/min) , feed is 33.

3ipm (845mm/min) , use cooling fluid pressure to be 735psi/3.

Of 2-gpm inside cooling means, the treatment quality of aperture reachs IT8 level. A lot of people get all straight chamfer call " G is gotten " , but this is not exact, actually " G is gotten " it is Accuromm USA Int only.

The some that the company produces kind the brand name that straight chamfer gets, the predestined relationship outside the rear of this kind of broach can press smooth action to arriving since hole wall. Compare all sorts of aperture to machine cutting tool accessible hole wall is bright and clean degree, generally speaking, high-speed steel broach is 125-rms about, efficient broach is in chamfer of hard alloy helix about 63-rms less than, 3 chamfer reamer is 32-rms less than about, and G getting can achieve 16-rms or smaller, what already obtained precision work is bright and clean spend a level. To machine the aperture of different quality standard, accuromm company designed different broach, the G of this company gets the aperture that can satisfy standard of H9 class public errand commonly to machine a requirement, and broach criterion collect gets the G-7 of this company cut cut a function with bore with a reamer at a suit, the treatment of public errand of class of OK and contented H7 asks. For example, accuromm company listed to be gotten with straight chamfer G replace twist drill to be on aluminous material the treatment example of bore, the diameter that G gets is 0.

394 ″ (φ 10mm) , adoption cutting rate is 330ft.

/ Min (100m/min) , feed is 0.

008ipr (0.

20mm/r) , the result makes clear, kong Jia is versed in precision rises significantly, bore diameter error by original ± 0.

0032 ″ (0.

08mm) reduce ± 0.

0012 ″ (0.

03mm) . Below identical cutting parameter, if use G-7 broach treatment, bore diameter error still can be reduced to ± 0.

0008 ″ (0.

02mm) . The bore quality that gets as a result of straight chamfer is higher, to other Kong Jia is versed in working procedure also has profit greatly. Accuromm company points out, if need the aperture that machines to straight chamfer broach to undertake tap, its admirable dimension precision can make tap life raises about 50 % . The raises to ask its machine an object nearly always range of function of cutting cutting tool is narrower. Although straight chamfer is gotten,still do not calculate far going up is a kind of general cutting tool, but its scope of application is expanding ceaselessly however. The promotion application that straight chamfer gets is raising treatment efficiency and improvement two respects acquire workpiece quality very distinct benefit. H.



A flight of stairs of straight chamfer of hard alloy of a kind of whole that Precision company produces is gotten " Muilt-Drill " used TiAlN coating and inside cooling passageway design, apply to undertake on material of the short aluminium alloy that cut bits Kong He of bore, a flight of stairs pours horn to machine. Competitive Carbide Int.

The company produces " Insatiable G-Spot " the G-Spot straight chamfer this company gets special and compound cutting tool to be an organic whole with union of lumen milling cutter, use a cutting tool to be able to complete a variety of treatment of pair of workpiece geometry structures. Altogether of this cutting tool can complete operation of 9 kinds of treatment, include bore, external diameter (OD) pour horn and Huo aperture, internal diameter (ID) pour turning of horn and Huo aperture, external diameter (the prior operation of whorl workpiece) etc. Because the osculatory area between cutting tool and workpiece is large, add broach external diameter and workpiece to be contacted at 4 o'clock, because the cutting tool of this kind of twinset conduces to,maintain work place to stabilize, can have additional clamp effect to workpiece. Because straight chamfer broach has 2 first flank, this cutting tool not only can bore, still can have crowded smooth effect to aperture. This is spent with respect to the Kong Guangjie that means treatment to go out taller, linearity is better, as only as cutting blade the traditional broach photograph of a first flank is compared, the specific measure that can satisfy pair of aperture better asks. Compound cutting tool of use Insatiable G-Spot can replace 3 ~ at least 4 kinds of cutting tool, if use original cutting tool,machine namely, need changes a knife 3 times, complete operation of 4 kinds of treatment. Accordingly, this kind muti_function the use of compound cutting tool, machine efficiency to rising, shorten handling time has profit greatly. CNC Milling CNC Machining