CN1135947A - Method for repairing large gear wheels by position changing cutting and ring mounting to change teeth - Google Patents

Abstract

A method for repairing waste big gear includes turning off the excirde of the big gear and rehobbirg to obtain a new gear with less diameter and unchanged teeth number and modulus, turning off the teeth of small gear from their root to obtain a new shaft, manufacturing a toothed ring and sleeving the toothed ring onto the shaft by thermal installation method to obtain a new gear shaft.

Description

Use position changing cutting and method for mounting ring to change teeth and repair large gear

The invention belongs to metallurgical machinery and cement machinery field.

At present, metallurgy and cement industry, especially rolling machinery are used large gear widely, and its manufacturing time is long, the cost height.And in use, gear under all intact situation in all the other positions, promptly gives and scrapping for no other reason than that rippling, wear and tear, peel off.This situation ubiquity is huge waste really.

The objective of the invention is to avoid above-mentioned weak point of the prior art and a kind of large gear of will scrapping is provided, a small amount of cost of change expense is used position changing cutting and method for mounting ring to change teeth and is repaired, and its regeneration is used.

Purpose of the present invention can reach by following measure:

A kind of position changing cutting and Xiang Quan of using changes the method that tooth is repaired large gear, it is characterized in that:

A, with the gear wheel cylindrical on request turning go tool setting gear hobbing again behind the circle, drawn a reduced and the number of teeth, new gear that modulus is constant;

B, the tooth of pinion is fallen along spindle nose Qi Genche, obtain a new axle, process a gear ring more again, be enclosed within on the axle, can obtain a new tooth axle with hot charge practice.

The present invention has following advantage compared to existing technology:

1, save processing charges: the tens thousand of at least units of rolling mill gear cost, tens0000 to hundreds of thousands unit at most, repairs gear and tooth axle with this method, can normally use, and cost can be saved about half;

2, shorten the process-cycle: the large gear process-cycle generally needs can exempt or reduce technical process such as wooden model, moulding, casting, heat treatment, metalworking with this method reparation more than 1 year, and the process-cycle can shorten 2/3rds;

3, increase the service life: because pinion adopts the distance of shuffling, its meshing parameter improves, and owing to change the edge coil structures into, can select more excellent material for use, has improved heat-treatability, and prolong service life greatly.Facts have proved, can improve service life more than one times.

Fig. 1 is a gear wheel restorative procedure schematic diagram of the present invention

Fig. 2 is a schematic diagram before gear shaft of the present invention is repaired.

Fig. 3 is a schematic diagram after the gear shaft reparation of the present invention.

Fig. 4 is that the present invention interferes the calculating schematic diagram.

Fig. 5 is a slip ratio checking computations schematic diagram of the present invention.

Fig. 6 is a slip ratio schematic diagram of the present invention.

Fig. 7 is that pressure of the present invention is than the checking computations schematic diagram.

Fig. 8 is that pinion end face of the present invention changes schematic diagram.

Fig. 9 is that gear wheel end face of the present invention changes schematic diagram.

Among Fig. 11 ' be circle outside the original gear, 2 ' be the flank profil of original gear, 3 ' be the tooth root of original gear, the 1st, circle outside the new gear, the 2nd, the flank profil of new gear, the 3rd, the tooth root of new gear, 4 is gear rings among Fig. 3, the 5th, gear shaft.

Below in conjunction with accompanying drawing the present invention is further described:

One, about the elaboration of fatigue problem

Gear wheel is repaired with the displacement principle, and is no doubt feasible, but this gear used for many years, whether produced metal fatigue, promptly enables usefulness, and how is the life-span? about this problem, we are set forth as follows:

Metal material stands certain stress-number of cycles and the maximum stress that can bear when still fatigue fracture not taking place is called fatigue limit under the effect of symmetric curvature stress.Concerning steel, reach 10 as number of stress cycles ⁶～10 ⁷Inferior when still fatigue fracture not taking place, then can think, along with the increase of stress-number of cycles, fatigue fracture will no longer take place.This gear material is a cast steel, and above-mentioned theory is suitable for it.The number of stress cycles that this gear bore has substantially exceeded 10 ⁶～10 ⁷Inferior.Therefore can think that when this gear used in the past, its actual stress value was lower than fatigue limit, otherwise disconnected for a long time, the past is not disconnected, even stress-number of cycles increases, and can broken teeth yet.So, destroying problem for flexural fatigue, needn't worry.

Gear also bears contact shear stress and contacts compression except bearing bending load on the flank of tooth.Under the long term of this stress, the flank of tooth produces blind crack gradually, and under lubricating oil infiltration and the effect of flank of tooth pressure, this blind crack is expanded gradually and formed the point-like pitting, tired spot corrosion that Here it is.This phenomenon promptly occurs after one, two month in this gear carrying, and constantly development, just can not use later in several years.As long as we machine away the spot corrosion layer, the contact fatigue problem does not just exist, and this does the purpose that gear modification is repaired just.

We once carried out painted and magnetic powder inspection to 170 pairs of teeth of this gear, did not all find fatigue crack at the root of tooth.The rippling layer is checked after with grinder buffing, found generally 0.2～0.3mm under spot corrosion of tired layer depth.So as long as cutting depth is selected proper, contact fatigue can be eliminated.

Two, modification Coefficient Selection

The purpose of repairing should be at first satisfied in the selection of modification coefficient ξ, and the spot corrosion wearing layer of promptly pruning after the displacement recovers involute profile.The interrelated data introduction adopts following formula to determine modification coefficient: $-{\mathrm{\&xi;}}_2=\frac{L_{02}-{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A9511104000181.png"\; state="\{\{state\}\}">L</figure-callout>}}_2^{\&Prime;}+\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A9511104000181.png"\; state="\{\{state\}\}">L</figure-callout>}}_2}{2\&CenterDot;m\&CenterDot;{\sin \mathrm{\&alpha;}}_0}$ L in the formula ₀₂---non-displacement public law line length;

L ₂"---actual public law line length behind the gear wear;

Δ L ₂---recover the attenuate amount that flank profil needs;

But this formula is serious or facewidth b＜L in the gear plastic deformation ₀₂Sin β _f, can't measure actual base tangent length L ₂" time, can not use.The gear that we will repair is exactly this situation.So, have to (this gear spot corrosion be dark about 2～3mm), determines the attenuate amount, calculates modification coefficient according to the pitting penetration of directly measuring.Because of the monolateral increase and decrease amount of transverse tooth thickness after the displacement

ΔS＝ξ _n·m _n·tgα _n，

So So tentatively choose ξ _N2=-0.5.

On the other hand, because this is to the speed ratio of gear big (i=6.071), pinion contact strength, bending strength and duty cycle number average are mutually far short of what is expected than gear wheel, so also want by the displacement correction, improve the meshing performance of pinion,, select best modification coefficient from this principle.According to the interrelated data introduction:

1, from making bending strengths such as pinion acquisition and improving the quality index of contact strength, choose:

ξ _n1＝0.42 ξ _n2＝-0.42

2, from improving the wear-resisting anti-bonding performance that undermines:

ξ _n1＝0.39 ξ _n2＝-0.39

3, from improving bending strength: ξ _n=± 0.52.

4, according to Britain Man Teli displacement system, for making Z ₁Curved intensity such as＞20 pinion acquisition are also improved flank profil curvature, choose: ${\mathrm{\&xi;}}_1=0.5\&times;\&lsqb;1-\frac{Z_1}{{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="A9511104000181.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2}\&rsqb;$ $=0.5\&times;(1-\frac{28}{170})=0.418$

Comprehensive above consideration, we get: ξ _N1=0.5; ξ _N2=-0.5.

Three, the modification coefficient of being got is checked

Behind the gear modification, cause the variation of a series of meshing performances, these change, and favourable one side disadvantageous one side is also arranged, and this gear is great to the relations of production, must conscientiously be checked:

1, the checking computations of gear tooth interference

Figure 4 shows that the situation of hobboing cutter cutting gear, when the addendum line of cutter just by engagement limit N ₁During point, then the flank profil beyond the basic circle is involute; As the addendum line of cutter at N ₁Below the point, establish it and path of contact intersects at B ₂ ¹Flank profil B then ₂ ¹K is an involute, and B ₂With interior part, then be outside circle B ₂ ¹The non-involute flank profil that cuts out is called easement curve.

During a pair of gear drive, contact with the easement curve of another Gear Root, then will produce easement curve and interfere, in the time of designing profile modified gear, tackle this and check, avoid that this thing happens as the tooth top involute of a gear.

Make gear that easement curve not take place and interfere, condition is that flank profil active section starting point should be in the involute part of flank profil, just: the pressure angle of flank profil active section starting point should be more than or equal to the pressure angle of flank profil involute starting point.

1) the check formula that easement curve is interfered does not take place in pinion $\mathrm{tg}{\mathrm{\&alpha;}}_s^{\&prime;}-\frac{Z_2}{Z_1}({\mathrm{tg\&alpha;}}_{\mathrm{as}2}-\mathrm{tg}{\mathrm{\&alpha;}}_s^1)$ $\&GreaterEqual;\mathrm{tg\&alpha;s}-\frac{4(f_s-{\mathrm{\&xi;}}_{s1})}{Z_1\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A9511104000181.png"\; state="\{\{state\}\}">sin</figure-callout>}2{\mathrm{\&alpha;}}_s}----\left(1\right)$ α in the formula _s" an end face transmission angle of engagement, for high displacement transmission:

α _sThe one end face reference circle angle of engagement;

Z ₂(the gear wheel number of teeth)=170;

Z ₁(the pinion number of teeth)=28;

f _s(end face tooth depth coefficient)=0.88;

ξ _S1(end face modification coefficient)=0.44;

α _As2---gear wheel tip circle transverse pressure angle

=23.173 ° because of (1) formula left end=0.3259, and (1) formula right-hand member=0.3246 is so left end＞right-hand member is interfered so easement curve does not take place pinion.

2) the check formula that easement curve is interfered does not take place in gear wheel ${\mathrm{tg\&alpha;}}_s^{\&prime;}-\frac{Z_1}{Z_2}({\mathrm{tg\&alpha;}}_{\mathrm{as}1}-{\mathrm{tg\&alpha;}}_s^{\&prime;})$ $\&GreaterEqual;{\mathrm{tg\&alpha;}}_s-\frac{4(f_s-{\mathrm{\&xi;}}_{s2})}{{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="A9511104000181.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A9511104000181.png"\; state="\{\{state\}\}">sin</figure-callout>}2{\mathrm{\&alpha;}}_s}----\left(2\right)$ α in the formula _s', α _s, Z ₁, Z ₂, f ₂The same;

ξ _s2＝0.44；

=32.386 ° because of (2) formula left end=0.377, and (2) formula right-hand member=0.3696 is so left end＞right-hand member is interfered so easement curve can not take place gear wheel.

2, the checking computations of registration

Behind the gear height change, path of contact will shorten, thereby registration will reduce.This is a double helical tooth to gear, Face contact ratio ε _βBigger, the reduction of transverse contact ratio ε is to total registration ε _∑Influence is little.Now be calculated as follows: ${\mathrm{\&epsiv;}}_{\mathrm{\&Sigma;}}=\mathrm{\&epsiv;}+{\mathrm{\&epsiv;}}_{\mathrm{\&beta;}}=\frac{1}{2\mathrm{\&pi;}}\&lsqb;Z_1(\mathrm{tg}{\mathrm{\&alpha;}}_{\mathrm{as}1}-{\mathrm{tg\&alpha;}}_s)+Z_2({\mathrm{tg\&alpha;}}_{\mathrm{as}2}-{\mathrm{tg\&alpha;}}_s)\&rsqb;+\frac{b\sin {\mathrm{\&beta;}}_f}{{\mathrm{\&pi;m}}_n}$

＝1.374+6.8＝8.174

[b in the formula (gear width)=2 * 360=720]

In like manner can get the not transverse contact ratio during displacement of gear:

ε′＝1.4575。

So the displacement rear end right reduction value of heavy dm is:

ε′-ε＝0.0835。

3, add the checking computations of cutter interference in man-hour

The pinion number of teeth is 28, considerably beyond the minimum tooth number Z that does not produce cutter interference _Min(Z _Min=12), and pinion adopts the distance of shuffling, and hobboing cutter is away from engagement limit N, thereby more can not produce cutter interference, so need not check.Gear wheel adopts to bear and moves distance, though hobboing cutter shifts near engagement limit N, a lot of (Z of its number of teeth ₂=170), the engagement limit is very far away from hobboing cutter, and the cutter interference phenomenon can not take place.

4, the checking computations of slip ratio

Gear drive situation such as Fig. 5 slide because flank profil exists relatively in meshing point, and under the effect of drive positive pressure profile wear.Its degree of wear can be represented with slip ratio, slip ratio distribution situation such as Fig. 6.

By Fig. 5, Fig. 6 as seen, behind the gear modification, because the increase of pinion gear teeth tip circle, so B ₁Point moves to B ' along path of contact ₁, 1 ₁Increase; Simultaneously, the gear wheel outside circle dwindles, B ₂Point moves to b along path of contact ₂ ¹, 1 ₂Reduce.So pinion slide coefficient u after the displacement _1maxReduce (reducing to 0.313) by 0.387; And the maximum slide coefficient u of gear wheel _2maxIncrease (increasing to 0.11) u by 0.076 _1maxWith u _2maxNumerical value have near trend, the pinion abrasion condition improves relatively.

5, the checking computations of pressure ratio

The pressure ratio is meant the ratio of each meshing point contact stress of flank profil in the gear drive and contact stress when the node, and its distribution situation as shown in Figure 7.When this does not do the displacement correction to gear pressure than ξ at B ₂, B ₁Point reaches maximum, and its value is respectively 1.26 and 0.845.Since displacement, B ₂Point moves to B ' ₂B ' ₁, point moves to B ' ₁The ξ value becomes 1.10 and 0.88 respectively.As seen, behind the gear modification, pinion (tooth root) pressure is than descending to some extent.This to gear in, pinion is a weak link, its pressure ratio has descended, weak link has been strengthened, transmission has also just improved.

6, the checking computations of pinion end face profile of tooth variation

Behind the gear modification, the pinion root will thicken, and the top will come to a point, this gear be the enclosed transmission without quenching, its hardness HRC＜38, tooth top circular tooth thickness S _A1Answer 〉=0.15～0.25mn, and should be not narrow.Therefore, reply tooth top circular tooth thickness checks, and checks circular tooth thickness such as reference circle, root circle simultaneously, makes the flank profil contrast of displacement front and back.

If the outside circle transverse circular thickness is S after the displacement _A1, then $S_{a1}=d_{a1}\&lsqb;\frac{\mathrm{\&pi;}+4\&CenterDot;{\mathrm{\&xi;}}_{n1}\&CenterDot;{\mathrm{tg\&alpha;}}_n}{2Z_1}+\mathrm{inv}{\mathrm{\&alpha;}}_{s1}-\mathrm{inv}{\mathrm{\&alpha;}}_{\mathrm{as}1}\&rsqb;$ D in the formula _A1(pinion outside diameter circle)=509.09+2 (1+0.5) * 16=557.09Z ₁, α _S1, α _As1Ditto, inv is an infolute function.So S _A1=11.97

Equally can in the hope of:

Reference circle (d _F1=509.09) transverse circular thickness:

S _F1=35.18 root circle (d _I1=485.09) transverse circular thickness:

S _i1＝41.43

Can try to achieve this gear transverse circular thickness that outside circle, reference circle, root circle etc. are not located during displacement equally.

Figure 8 shows that gear each end surface of flank profil (among the figure shown in the solid line) each end surface size of flank profil during displacement (among the figure shown in the dotted line) to the greatest extent cun and not after displacement.

As seen from Figure 8, because displacement, the pinion head transverse circular thickness becomes 11.97 by 14.08, changes not quite, and on License Value, the tooth root transverse circular thickness then becomes 41.43 by 36.37, thickens 5.06, and the bending strength of tooth root strengthens bigger.

7, the checking computations of gear wheel contrate tooth profile variation

Behind the gear modification, gear wheel for negative move apart from the time, then tooth top will thicken and tooth root with attenuate, the bending strength of tooth root will weaken, and will be big as its attenuate amount, then must its bending strength of checking computations.

Figure 9 shows that gear each end surface size of flank profil (among the figure shown in the solid line) and each end surface size of flank profil during displacement (among the figure shown in the dotted line) not after displacement.Dash area is for revising cutting output among the figure, and as seen, the cutting output of tip circle, reference circle, the wide both sides of root knuckle-tooth is respectively 3.33,3.31 and 3.265.Be enough to satisfy the purpose of eliminating spot corrosion.

As seen from Figure 9, because displacement, gear wheel tooth top transverse circular thickness becomes 15.30 by 15.09, and the tooth root transverse circular thickness becomes 43.01 by 43.88, attenuate 0.87, and variable is small, and is minimum to the bending strength influence of tooth root, can ignore.

Go up checking computations according to this, can think the modification coefficient ξ that is got _N1=0.5, ξ _N2=-0.5, the purpose of eliminating the spot corrosion layer can be satisfied, and the intensity of pinion can be improved, improve meshing performance, and can not produce adverse consequences, be feasible, suitable therefore.

Four, pinion hot charging and relevant issues

Pinion was a whole tooth axle originally, flank of tooth heavy wear, but axle body and axle journal are excellent, still can utilize.We cut this axle in decision along  360mm place, the flank of tooth and hub portion car are gone, and car becomes the circular shaft of  361mm diameter, joins a gear ring endoporus  360mm in addition, (sees its hot charging for details Fig. 1) on axle body.This has not only utilized axle body (surplus only this just can save 10,000 yuan), and gear ring itself is not subjected to involving of axle, can select the high duty alloy steel of high-mechanical property separately for use, improves intensity; Simultaneously, gear ring is compared with whole tooth axle, and forging and heat treatment performance are all better, can improve gear hardness and intensity, increase the service life.

Certainly, do like this, also can reach fit in the processing and bring new problem on the structural design.Now will imagine with solution and be described below:

1, to the requirement of gear ring material property

The long-term repeated loading of rolling mill gear, impact load is big, therefore, high intensity, hardness and good impact flexibility be arranged.Originally whole tooth axle is 45 ^#Steel is improper certainly.Silicomanganese class steel has higher intensity, good wearability, but toughness is relatively poor, makes the bigger gear ring of the hot charging magnitude of interference so be unsuitable for, and this may cause fracture.Therefore, decision has good modified performance and is suitable for doing the 35CrMoV steel of large forgings with having higher-strength, hardness and impact flexibility concurrently.

In addition, forging ratio, the Forging Technology to the tooth base proposed higher requirement.Through the ultrasonic examination check, do not find the inside and outside defective of equivalent  more than 2.Hardness Surveillance proves that also the gear ring quenching and tempering hardness is than more than the high HB50 of whole tooth axle quenching and tempering hardness.Past whole tooth axle quenching and tempering hardness, the practice examining value does not all reach designing requirement, and this may amass greatly with whole tooth axial section, the quenching degree difference is relevant.After estimating to change gear ring into, can increase the service life.This tooth axle is uncapped after eight months in running and is checked discovery, and its spot corrosion is much slight with all more former whole tooth axle of wearing and tearing.

2, the magnitude of interference chooses

The root diameter  485.09mm of this gear ring, diameter of bore  361mm, wall thickness only has 62.045mm, and is thiner.Therefore, the selection of the hot charging magnitude of interference must be prudent, and is too small as the magnitude of interference, and then axle may produce relative slip and can not transmit moment of torsion effectively with gear ring; Excessive as the magnitude of interference, then gear ring may burst apart.

Through calculating and consideration repeatedly, getting the design amount of being full of is 0.2～0.25mm, and the actual measurement interference of processing back is 0.25mm, calculates that thus the maximum pressure of gear ring endoporus is 309.4kgf/cm ², tangential stress is 775kgf/cm ²Through checking computations, plastic deformation can not take place in this gear ring, surely not bursts apart.

3, the processing and the hot charging points for attention of gear ring and axle

The theory of the magnitude of interference is calculated, guarantee by machining accuracy, otherwise, calculate accurately also of no avail again.Therefore, we have considered the influence of this factor when choosing the magnitude of interference, strengthened the magnitude of interference.In addition, drawing also stipulate gear ring endoporus ( 361mm, long 960mm) and axle ovality, the post degree is not more than 0.02, fineness is 7.Like this, the theoretical containing area that calculates could be realized.

Heating means are also very important during hot charging, and are improper as heating means, may make the gear ring distortion, cause connecting and lose efficacy.Therefore, we stipulate and must oil bath heat, and heating-up temperature is controlled, and the gear ring temperature is slowly risen equably, and forbid directly roasting heating with naked light.

Five, gear wheel processing points for attention

In order to guarantee repairing quality, the gear wheel work in-process should be noted following item:

1, the setting angle of hobboing cutter

During gear hobbing, the helix of hobboing cutter must be strict consistent with the helix of working, so the established angle A of hobboing cutter must be correct, not so will influence by the transverse tooth thickness of gear cutting machine and tooth curve.

At Helical Gear Hobbing and gear compound graduation circle helixangle _rGreater than hobboing cutter calibration cylinder lead angle λ _f, when both hand of helix is identical: A=β _i-λ _fWhen both hand of helix is opposite: A=β _f+ λ _f

But when rolling cut displacement helical gear, the size at A angle also with end face coefficient of offset ξ _aRelevant, because the cutting nodel line of this moment will mobile ξ _am _a(m _aBe transverse module).So hobboing cutter divides the helical angle on the cylinder just to change at workpiece, establishes it with λ _ξExpression, then λ _ξCan be calculated as follows: So when rolling cut displacement helical gear, established angle is as follows:

When workpiece is identical with the cutter hand of spiral: A=β _f-λ _ξWhen workpiece is opposite with the cutter hand of spiral: A=β _f+ λ _ξ

In general, at ξ _sNumerical value hour, this influence can be ignored.But this a pair of gear ξ _sBigger, and modulus is big, the number of teeth is many, diameter is big, and tooth curve and tooth thickness error will be brought very big problem to running-in and running, therefore, when cutter is installed, must consider this influence.

2, control gear radially reaches end face run-out

This gear wheel cooperates tighter with axle, axial compression is gone out the comparison difficulty, and may be with axle and hole scratch.Tape spool processing top circle and gear hobbing, more should note control gear radially and end face run-out.Because top circle and end face are the foundations that transfer in the clamping school, it is excessive to beat as it, will have a strong impact on the gear hobbing quality.For large-scale like this gear, more should be specifically noted that this problem.

This gear is processed on  6.3mm vertical lathe.On vertical lathe, press from both sides a 80mm steel plate earlier, car one endoporus, its aperture is than the big 0.06mm of gear wheel spindle nose diameter, and end car one taper guide end is coated with butter on this hole, with in the vertical patchhole of Gear axis, finds the center, lower end so then; Above again end-journal is that benchmark finds the center.The gear of centering processing radially and end face run-out can be controlled well like this.

3, note the helical angle error

The painstaking phenomenon of past our factory rolling mill gear mesh linea angulata is more, and this is the two inconsistent performances of The Gear Helix of intermeshing.For this reason, we will spend a lot of manpowers and time to go to carry out the reconditioning running-in at every turn and be difficult to thoroughly elimination.Current displacement reparation, this problem has all been noted by we and Peng Pu Machines Plant, the gear hobbing change gear of big pinion than with line on all make every effort to accomplish accurate consistent.Therefore, this a pair of gear is very much consistent at processing rear screw line.Contact Tooth length is not stung the diagonal angle phenomenon more than 95%, and the reconditioning running-in of not taking time has just successfully dropped into production run.

Claims (1)

1, a kind of position changing cutting and Xiang Quan of using changes the method that tooth is repaired large gear, it is characterized in that:

A, with the gear wheel cylindrical on request turning go tool setting gear hobbing again behind the circle, drawn a reduced and the number of teeth, new gear that modulus is constant;

B, the tooth of pinion is fallen along spindle nose Qi Genche, obtain a new axle, process a gear ring more again, be enclosed within on the axle, can obtain a new tooth axle with hot charge practice.

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