2016年11月25日星期五
2016年11月11日星期五
2016年11月8日星期二
The project and technology of Halnn superhard cbn
inserts turning Gear
With the rapid development of the auto
industry, it also lead the rapid rise of the auto downstream industry, such as
auto parts and other industries. And with the mass production of cars, a lot of
manufacturers which processing auto parts belong to mass production, such as
automotive gear, gear shaft and other components. This article describes the
selection about process technology and materials of auto parts, and how to
process auto gear.
Part
1 The material and performance of the auto gears
Currently, there are 18-30 pieces gears per
auto usually, the gear is the main basal transmission parts in the car
industry, its quality directly affects the noise, stability and service life of
the car. And choose different gear material, the gear will play a different
role, such as automotive transmission gears, drive axle pinion gear, driver
different gear and others often used 20CrMoTi,20CrMo as materials; automotive
crankshaft gear often used 40,45 or 40Cr as Material. In order to make the car
gear have a higher hardness, strength and flexural fatigue strength and contact
fatigue strength (resistance to fatigue pitting)when running, usually use heat
treatment process to improve the hardness, wear resistance and fatigue strength
of the gear .
Part
2 The heat treatment process for Automobile Gears
The Heat Treatment for Automotive gear
usually include: normalizing, quenching, carburizing and other processes,
normalizing happened before process the parts for removing the internal stress
and increase the hardness of the material; quenching and carburizing generally
happened after rough processing the gear, in order to obtain a high surface
hardness, high wear resistance and fatigue strength, and the unit has a strong
heart and toughness to keep low-carbon steel after quenching, the work piece
can withstand shock loads, for extending the life of the parts. You need choose
the different heat treatment process according to the different materials. The
important gear (such as transmission wheel 20CrMoTi material) required
carburizing after heat treatment, for improving the wear resistance and fatigue
resistance. In order to ensure the core part has enough strength and toughness,
the material harden ability need a high requirements, the core parts hardness
should be 35 ~ 45HRC, hardness of surface was 58-64HRC.
Part
3 The machinery processing technology and Inserts selection for auto gear
We had introduced the auto gearbox
wheel(20CrMoTi materials) heat treatment process above , Now here is the brief
processing line: Turning-Forged-normalizing-roughing-carburizing- quenching and
tempering-finishing process-shot-grinding-Assembly. The hardness of 20CrMnTi
material gear after heat treatment is HRC 58-64.While the hardness of other
material’s gear was generally HRC45 or more after heat treatment, and there
will inevitably be some distortion problems during the heat treatment ,will
make trouble for finishing, so it is so important to choose the right inserts material
when finishing process, as the car gear requires high accuracy, high quality,
and the need to ensure the efficiency when mass production machining. There are
three types materials for inserts on the market currently, which are coated
carbide tools, ceramic cutting tools and cubic boron nitride(CBN) cutting
tools, although the hardness and strength of coated carbide insert is better
than uncoated carbide insert, the performance was the same as the surface
wear-resistant layer is thin. So we did not suggest you choose the coated
carbide tools when large volume processing. Of course the Ceramic inserts was
brittle, and only was suitable for finish process the material which hardness
was between HRC45 to 55.
However Cubic boron nitride(CBN) cutting tools,
has a higher hardness, higher strength and better wear resistance than the other
two kind cutting tools we mentioned. Especially the non-metallic adhesive cbn
insert researched by Halnn superhard. The development of non-metallic adhesive cbn
inserts which was researched by Halnn superhard, which is a CBN insert company
solving the problem of finishing processes.
The CBN inserts from Halnn Superhard can be
used for turning the hard material all around and efficient. Halnn superhard cbn
insert company was the first one to put forward to the conception of solid cbn
inserts.
Now we will introduce how to choose the
Halnn cbn inserts to process the gear.
Part
4 Halnn super-hard CBN inserts finishing process the gear
The working allowance is generally less
than 0.3mm when finish turning gear, Halnn super-hard cbn inserts research
BN-H10 and BN-H20 Non-metallic adhesive cbn inserts for finish turning gear. The
two grade inserts both belong to the welded cbn inserts.
Following we will introduce how to choose
the right grade inserts according to the different condition.
(1)Continuous turning conditions: Select
BN-H10 cbn inserts,BN-H10 welded cbn insert has a high hardness, wear
resistance and good resistance to chipping damage,suit for high-speed and
continuous finishing cutting conditions,cuttingparameters:ap≤1mm,Fr=0.05-0.35mm/r, Vc= 60~250m /min.
Application Case: Turning the gear which
hardness was between HRC58 to 63.
Cbn inserts grades: BN-H10;
Cutting parameters: ap=0.2mm,Fr=0.1mm/r,Vc=180m/min.
Processing steps: Dry cutting.
Processing effect: life is 4 times longer
and only cost 40% than ceramic tools.
(2)Interrupted turning conditions: Interrupted
turning was named that there is groove in the gear end’s hole.This operating
mode should select Halnn superhard cbn inserts BN-H20 grade, this grade not
only has a higher hardness, excellent wear resistance and impact resistance
,but also has a multi-blade numbers, reduce the tool costs.
Application Case: Turning the end surface
of the gear which hardness is between HRC58 to 63
Cbn inserts grade :BN-H20 grade;
Cutting parameters: ap=0.25mm,Fr=0.1mm/r,Vc=120m/min.
Processing methods: Dry cutting.
Processing effect: Compared with European
brand PCBN inserts, Halnn BN-H20 tool has a longer life, and only cost 1/2
price than European brand PCBN inserts .
So Halnn superhard tools will be your best
selection for turning the Gear. If you would like to know more about cbn insert
turning gear, please check the following link http://www.halnntools.com/news/case/126.html,or
send us email halnntools@gmail.com,Or
contact with me directly:whatsapp:+8618695866134.
Machining
performance of CBN inserts for hard turning bearing
The two main application areas for CBN inserts include
1.Turning hardened steel
2.Turning gray cast iron
Now we will introduce the application of cbn insert
on hard turning hardened steel part---bearing steel .
Normally CBN only works when the steel component is
hardened(which means through heat treatment), with a hardness above HRC50. In
its original state, thse material is usually around 250 HB, but the hardness is
increased significantly through deformation hardening when used, without any
loss of toughness.The hardness is also very difficult to measure with high
accuracy due to the high level of work hardening.
The deformation hardening will affect the material
also during machining, and this impacts the selection of cutting tools
materials which can be used for machining.
Cutting data when using carbide insert has to be
very low. Normally, the cutting speeds can be range 20 to 30 m/min. But if with
CBN insert, cutting speeds can be increase to 200m/min, which significantly
improve the processing efficiency.
One typical application Case as follows: Halnn CBN
inserts has a long experience and has been very successful on hard turning
hardened steel Bearing steel.
|
Machining Part：Bearings
Machining Materials:GCr15 WorkpieceHardness:HRC62 Inserts Grade:BN-H11 DNGA150408 Cutting Type: Dry Cutting Cutting Parameters: ap=2.5mm,Fr=0.12mm/r,Vc=140m/min |
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Inserts Materials
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Linear Speed(m/min)
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Lifetime/cutting dege
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Surface Roughness
|
|
Halnn BN-H11
|
140
|
12
|
Ra0.8~1.6
|
|
Imported PCBN inserts
|
140
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10
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Ra0.8
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