CN103831481A - Optimization method for positive rake angle gear hob - Google Patents

Optimization method for positive rake angle gear hob Download PDF

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Publication number
CN103831481A
CN103831481A CN201410126263.7A CN201410126263A CN103831481A CN 103831481 A CN103831481 A CN 103831481A CN 201410126263 A CN201410126263 A CN 201410126263A CN 103831481 A CN103831481 A CN 103831481A
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Prior art keywords
hob
hobboing cutter
angle
rake angle
gear
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CN201410126263.7A
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CN103831481B (en
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张勇
杨永娟
李时威
杨风军
程会民
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Xi'an North Electro-Optic Technology Defense Co Ltd
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Xi'an North Electro-Optic Technology Defense Co Ltd
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Abstract

The invention relates to an optimization method for a positive rake angle gear hob. The optimization method for the positive rake angle gear hob is characterized by specifically including the following steps that firstly, a steel material is tungsten-molybdenum system high-carbon cobaltic super-hard high-speed steel of the type of W2Mo9Cr4VCo8; secondly, a hobbing device is adjusted according to machining parameters of a part, and the outer diameter and the hole diameter of the hob are increased, the number of hob chip containing grooves is selected and does not have the common divisor with the number of hob heads, and the angle of a reference circle radial rake angle is determined; thirdly, a relief angle of a top edge of the hob is increased by increasing the relief grinding amount of the hob; fourthly, the hob manner is a positive rake angle spiral groove hob manner, and the cutting conditions of edges of the two sides of the hub are consistent to reduce errors caused by the hob. It is ensured that a tooth error is smaller than an allowable value. The positive rake angle hob can relieve chip deformation and friction generated by chip passing through a front hob surface, and therefore cutting force can be relieved, the cutting temperature can be lowered, the service life of the hob is prolonged, and the quality of a machined tooth surface is improved. The problem that a 6-level precision thin wall titanium alloy gear part is difficult to machine is solved.

Description

A kind of optimization method of positive rake angle gear hob
Technical field
The present invention relates to take turns hobboing cutter, specifically a kind of optimization method of positive rake angle gear hob.Belong to mechanical field.
Background technology
Tooth Profile Machining is the key of Gear Processing, and the principal element that affects profile accuracy is hobboing cutter precision.During due to Tool in Cutting titanium alloy, will bear larger moment of torsion and cutting force, and cutter is interrupted cut during due to rolling cut, the load that withstands shocks, machining condition is comparatively severe, therefore cutter must have enough intensity and toughness; Due to titanium alloy material good toughness, add man-hour cutter sharp, therefore cutter material must have enough antiwear properties; Due to the poor thermal conductivity of titanium alloy, heat mainly concentrates on cutting region, and cutter also must have thermohardening.Mainly bear the gear part of the conventional material such as 40Cr, 45 steel due to my company and process, cutter for gear wheel also can only meet the processing request of conventional material.Therefore, adopt existing general gear hob to be not suitable for machining titanium alloy gear, need design specialized hobboing cutter.
Gear hob is by a kind of generating tool of helical gear theory of engagement machining cylindrical gear.Profile of tooth in gear end cross section is involute, and therefore, the basic worm of gear hob should be involute helicoid worm.In the time that gear hob adopts involute basic worm, it is not straight line that the axis of its side shovel face cuts shape, but curve, this makes to manufacture and checks hob profile very difficult.Current of home make gear hob is all not according to involute helicoid worm appearance, but adopt approximate appearance method to carry out design gear hobboing cutter to replace involute hob, the most frequently used approximate appearance method is using the side shovel face of hobboing cutter as Archimedes' helicoid, axial truncatus is straight line, manufactures and checks than being easier to.But while replacing involute hob cutting with it, caused in theory certain profile error, i.e. the appearance error of profile of tooth hobboing cutter, fine finishining hobboing cutter and standard hob, for the ease of manufacturing and measuring, generally all adopt 0 ° of anterior angle.Because this product parts precision is high, thin-walled, poor rigidity, and titanium alloy material elastic modelling quantity is little, (b) height of σ s/ σ, the characteristics such as processing resilience, should adopt the AA level positive rake angle hobboing cutter that cutting ability is superior to yield tensile ratio when design.
Production practices in recent years prove, positive rake angle hobboing cutter can reduce the friction that chip deformation and smear metal are flowed through on rake face, thereby can reduce cutting force, reduces cutting temperature, improves the life-span of hobboing cutter and the quality of the processed flank of tooth.But anterior angle selects improper meeting that profile error is strengthened, particularly 6 class precision thin-wall titanium alloy gear parts, required precision is high, and part thin-walled, process yielding, simultaneously because titanium alloy belongs to unmanageable alloy material, the machining accuracy difficulty that guarantees part is larger, especially tooth processed adds that man-hour tool wear is fast, and working (machining) efficiency is low, and precision is difficult to reach designing requirement.Therefore, need, to positive rake angle gear hob reference circle anterior angle appropriate design, guarantee that profile error is less than permissible value.
Summary of the invention
The object of the invention is: a kind of optimization method of positive rake angle gear hob is provided, and the method guarantees that profile error is less than permissible value; Its positive rake angle hobboing cutter can reduce the friction that chip deformation and smear metal are flowed through on rake face, thereby can reduce cutting force, reduces cutting temperature, improves the life-span of hobboing cutter and the quality of the processed flank of tooth.Solve the unmanageable problem of 6 class precision thin-wall titanium alloy gear part.
Technical scheme of the present invention: a kind of optimization method of positive rake angle gear hob, is characterized in that: it specifically comprises the steps:
It is that tungsten is high-carbon cobalt-containing super-hard type high-speed steel that step 1) is selected Steel material, and its model is W2Mo9Cr4VCo8;
Step 2) according to the machined parameters of part, adjust gear hobbing equipment, increase external diameter and the aperture of hobboing cutter, select hobboing cutter chip pocket number and with hobboing cutter head number without common divisor, determine the angle of reference circle radial rake;
Step 3) increases hobboing cutter top relief angle with increasing hobbing cutter spade milling amount;
Step 4) hobboing cutter form adopts positive rake angle spiral flute hob form, guarantees that the machining condition of hobboing cutter two side edges is consistent, to reduce Forming errors;
Step 5) adopts Cutting-Tool Coating Technology, makes coefficient of friction and the reduced viscosity of hobboing cutter after coating.
In described step 1), hobboing cutter external diameter is that φ 63mm, chip pocket number are 16, hobboing cutter head number is 3, the aperture φ 27mm of 3.5 ° of hobboing cutters of angle of reference circle radial rake, and in described step 3), top relief angle is 12 °; The described step 4) spiral fluted hand of spiral is dextrorotation.
Advantage of the present invention: positive rake angle hobboing cutter cutting ability is superior, as long as correct design positive rake angle and profile of tooth can make the appearance error of hobboing cutter very little, fully meets the processing request of high class gear.And because the axial truncatus of Archimedian side shovel face is linear, can adopt radially relief grinding, after refacing, still can keep profile accuracy.The present invention is by the design improvement of cutter, and adopts Cutting-Tool Coating Technology, solved the difficult problem that titanium alloy gear part cutting process exists, improve the durability of cutter, guarantee the crudy of part, greatly improved production efficiency, met the needs of batch production.
Accompanying drawing explanation
Fig. 1 is the Optimal Parameters that optimization method calculates according to the present invention and the hob profile schematic diagram designing;
Wherein, figure a is normal tooth profile; Figure b is axial tooth profile.
The specific embodiment
1, gear appearance error is calculated
In gear hobbing process, involute profile is mainly by keeping certain calibration to guarantee between hobboing cutter and tooth base, so profile error is mainly that hob profile determines.The appearance error delta f of hobboing cutter is exactly the tooth Shape Design error of path of contact direction, evaluation hob profile precision according to being tooth Shape Design error, according to the ratio (being less than 1:4.5) of tooth Shape Design tolerance and profile of tooth manufacturing tolerance, determine tooth Shape Design tolerance.Its AA and A level hob profile design tolerance numerical value are in table 1:
Table 1AA and A level hob profile design tolerance numerical value um
The computing formula of Archimedes rear flank knife face Forming errors Δ f is:
Δ f z = Δ f y = m n { Z o cos a n 2 ( inva y - inva o ) - sin a n 1 - c 2 tg γ o [ c 1 - Z o c 2 ( θ - θ o ) 2 sin λ o ] }
In formula: e-rake face off normal value,
D ao-tip diameter;
γ a-radial rake;
γ o-reference circle radial rake,
R o-reference radius;
θ othe value at-hobboing cutter reference circle place, θ o=-γ o;
The value at θ-hobboing cutter place, θ = arcsin ( - e r y ) ;
R y-calculation level radius, r y=r o+ c 1m n;
C 1-tooth depth coefficient, C 1value is 1 and-1, because point is selected in the up-and-down boundary place of profile of tooth active section;
R b-worm screw base radius, r b = r o cos a o = m n z o 2 tg λ b cos λ o ;
λ b-base circle of involute helicoid worm post lead angle.Also be the profile angle cos λ of a lateral tooth flank in basic circle section b=cosa ncos λ o;
λ o-reference circle lead angle, λ o = arcsin ( z o m n 2 r o ) ;
Z o-hobboing cutter head number;
α o-end face pressure angle of graduated circle,
α ythe pressure angle of any radius of-involute helicoid worm end face,
K-radially back-off amount, k = π d ao Z k cos λ o tg α a ;
c 2 = kz k 2 π r o ;
Z k-chip pocket number;
α a-top relief angle.
No matter hobboing cutter is spiral groove type or straight trough, and above formula is all suitable for.
2, positive rake angle gear appearance error analysis
6 class precision titanium alloy thin wall gear part parameters are in table 2:
Table 2 is by gear cutting machine parameter
The tooth Shape Design of gear hob, according to above formula calculating fraction-ness circle anterior angle and corresponding appearance error, result of calculation is in table 3:
Table 3 reference circle anterior angle and corresponding appearance error evaluation
Calculating by above-mentioned formula is known, and zero anterior angle hobboing cutter adopts bull can reduce designed toothform precision, but for positive rake angle hobboing cutter, a number is larger, best reference circle anterior angle is larger, select corresponding anterior angle and a number according to different accuracy grade, can meet the requirement of designed toothform precision.In the time of the larger anterior angle of needs, can increase a number.For the processing characteristics of 6 class precision titanium alloy thin wall gear parts, need design AA class precision and the superior positive rake angle hobboing cutter of cutting ability.As can be seen from Table 3, reference circle anterior angle γ obe 3.5 °, I type, a number Z obe 3 Forming errors: Δ f(+1)=-0.0394um ﹤ 0.1um(AA level hob profile design tolerance numerical value), can meet the requirement of AA level hob profile design accuracy completely, and a number Z of hobboing cutter o(3) do not have common divisor with the tooth number Z (224) of processed gear, can avoid the inconsistent phenomenon of processed gear tooth thickness, and in addition, multiple thread hob also can obviously improve gear hobbing working (machining) efficiency.Although due to the increase of hobboing cutter head number, the error of division between each screw thread will affect the precision of hobboing cutter, along with the raising of hobboing cutter manufacture level, multiple thread hob is widely used.
3, in order to ensure the machining accuracy of part, the profile error of hobboing cutter is carried out outside appropriate design, need be according to part material performance and required precision, the optimization method of a kind of positive rake angle gear hob of the present invention, take measures as follows:
It is that tungsten is high-carbon cobalt-containing super-hard type high-speed steel that step 1) is selected Steel material, and its model is W2Mo9Cr4VCo8(M42); The Main Function of cobalt can be strengthened age hardening effect, improves the hardness after thermohardening and heat treatment, and M42 has higher toughness, wearability, good thermal diffusivity simultaneously;
Step 2) according to the machined parameters of part (in table 2), adjust gear hobbing equipment, increase external diameter and the aperture of hobboing cutter, thereby increase the rigidity of hobboing cutter, improve cutting efficiency; Select more hobboing cutter chip pocket number and with hobboing cutter head number without common divisor, determine the angle of reference circle radial rake, the envelope error of the flank of tooth while reducing cutting, reduces the cutting load of hobboing cutter monodentate, to guarantee the machining accuracy of part;
Step 3) increases hobboing cutter top relief angle with increasing hobbing cutter spade milling amount; Make cutting edge sharp, reduce to process springback capacity and frictional force.
Step 4) hobboing cutter form adopts positive rake angle spiral flute hob form, guarantees that the machining condition of hobboing cutter two side edges is consistent, to reduce Forming errors;
Step 5) adopts Cutting-Tool Coating Technology, makes coefficient of friction and the reduced viscosity of hobboing cutter after coating; Can improve the processing characteristics of part, further improve the durability of cutter.And coating technology not only do not affect the dimensional accuracy of cutter, can also improve machining accuracy.Wherein, adopting Cutting-Tool Coating Technology is known technology.
By gear cutting machine parameter and table 3 positive rake angle gear appearance error analysis, calculate parameter optimum design of gear hob cutter after by above-mentioned steps according to table 2, the computing formula of hob profile major parameter is:
3.1, back-off amount k radially
For spiral flute hob radially the calculating formula of back-off amount be:
k = π d ao Z k cos γ z tg a a
In formula: γ z-reference circle lead of screw angle,
3.2, axial tooth profile
(1) positive rake angle helicla flute Archimedes' hobbing cutter axial profile angle computing formula is:
ctga xo = ctga no cos γ z ( 1 - kz k e 2 π r o 2 cos γ o ) ± kz k p k
In formula " ﹢ " number for right-hand hob left side, "-" number for right side, lefthand hob is contrary
P k-chip pocket helical pitch, p k=π d octg β k;
β k-chip pocket swing angle, β kz
(2) axial tooth top bevel angle
3.3, normal tooth profile
(1) normal pitch P no, P no=π m n
(2) normal pitch S no,
As shown in Figure 1, Fig. 1 is the Optimal Parameters that optimization method calculates according to the present invention and the hob profile schematic diagram designing; Wherein, figure a is normal tooth profile; Figure b is axial tooth profile.Parameter after optimum design of gear hob cutter is in table 4: the aperture of hobboing cutter is φ 27mm
Parameter after table 4 optimum design of gear hob cutter
Positive rake angle hobboing cutter cutting ability is superior, as long as correct design positive rake angle and profile of tooth can make the appearance error of hobboing cutter very little, fully meets the processing request of high class gear.And because the axial truncatus of Archimedian side shovel face is linear, can adopt radially relief grinding, after refacing, still can keep profile accuracy.By the design improvement of cutter, and adopt Cutting-Tool Coating Technology, solved the difficult problem that titanium alloy gear part cutting process exists, improve the durability of cutter, guarantee the crudy of part, greatly improved production efficiency, met the needs of batch production.
The Optimal Parameters of this optimization method solves the technical problem of 6 class precision thin-wall titanium alloy gear parts processing, and tooth especially processed adds that man-hour tool wear is fast, and working (machining) efficiency is low, and precision is difficult to reach designing requirement.Positive rake angle hobboing cutter cutting ability is superior, if generation appearance error is excessive but anterior angle is selected improper, can not meet the processing of high class gear.As long as correct design positive rake angle and profile of tooth, can make the appearance error of hobboing cutter very little.By the appropriate design to hobboing cutter parameter, and adopt Cutting-Tool Coating Technology, improved cutting ability and the service life of cutter, fully meet the batch machining requirement of high precision titanium alloy gear.

Claims (2)

1. an optimization method for positive rake angle gear hob, is characterized in that: it specifically comprises the steps:
It is that tungsten is high-carbon cobalt-containing super-hard type high-speed steel that step 1) is selected Steel material, and its model is W2Mo9Cr4VCo8;
Step 2) according to the machined parameters of part, adjust gear hobbing equipment, increase external diameter and the aperture of hobboing cutter, select hobboing cutter chip pocket number and with hobboing cutter head number without common divisor, determine the angle of reference circle radial rake;
Step 3) increases hobboing cutter top relief angle with increasing hobbing cutter spade milling amount;
Step 4) hobboing cutter form adopts positive rake angle spiral flute hob form, guarantees that the machining condition of hobboing cutter two side edges is consistent, to reduce Forming errors;
Step 5) adopts Cutting-Tool Coating Technology, makes coefficient of friction and the reduced viscosity of hobboing cutter after coating.
2. the optimization method of a kind of positive rake angle gear hob according to claim 1, it is characterized in that: in described step 1), hobboing cutter external diameter is that φ 63mm, chip pocket number are 16, hobboing cutter head number is 3, the aperture φ 27mm of 3.5 ° of hobboing cutters of angle of reference circle radial rake, and in described step 3), top relief angle is 12 °; The described step 4) spiral fluted hand of spiral is dextrorotation.
CN201410126263.7A 2014-03-31 2014-03-31 A kind of optimization method of positive rake angle gear hob Active CN103831481B (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106392203A (en) * 2016-11-08 2017-02-15 天津深之蓝海洋设备科技有限公司 Tool for machining modified gear of ROV propeller

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1430485A (en) * 1921-01-28 1922-09-26 Gould & Eberhardt Hob and method of making it
CN86208689U (en) * 1986-11-08 1987-12-05 阜新矿业学院 Assembling gear scraping hob made from hard alloy
JP2000158234A (en) * 1998-11-30 2000-06-13 Komatsu Ltd Dry type gear machining method and dry type gear machining tool
CN101028660A (en) * 2007-04-06 2007-09-05 吉林大学 Gear precisive hob configuration and its configured precisive hob
CN103028788A (en) * 2012-12-28 2013-04-10 天津大学 Designing method of straight-tooth slicing cutter without theoretical tooth profile error

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1430485A (en) * 1921-01-28 1922-09-26 Gould & Eberhardt Hob and method of making it
CN86208689U (en) * 1986-11-08 1987-12-05 阜新矿业学院 Assembling gear scraping hob made from hard alloy
JP2000158234A (en) * 1998-11-30 2000-06-13 Komatsu Ltd Dry type gear machining method and dry type gear machining tool
CN101028660A (en) * 2007-04-06 2007-09-05 吉林大学 Gear precisive hob configuration and its configured precisive hob
CN103028788A (en) * 2012-12-28 2013-04-10 天津大学 Designing method of straight-tooth slicing cutter without theoretical tooth profile error

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
唐建生: "《金属切削与刀具》", 1 June 2009, 武汉理工大学出版社 *
李芳等: "齿轮滚刀前角与齿形精度的关系", 《汽车技术》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106392203A (en) * 2016-11-08 2017-02-15 天津深之蓝海洋设备科技有限公司 Tool for machining modified gear of ROV propeller
CN106392203B (en) * 2016-11-08 2018-03-13 天津深之蓝海洋设备科技有限公司 A kind of cutter for being used to process ROV propeller repairing type gears
WO2018086441A1 (en) * 2016-11-08 2018-05-17 天津深之蓝海洋设备科技有限公司 Tool for machining modified gear of rov thruster

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