CN1314513C

CN1314513C - Crankshaft rolling strengthening process

Info

Publication number: CN1314513C
Application number: CNB2003101115752A
Authority: CN
Inventors: 李满良; 冯美斌
Original assignee: Dongfeng Motor Co Ltd
Current assignee: Dongfeng Motor Corp
Priority date: 2003-12-11
Filing date: 2003-12-11
Publication date: 2007-05-09
Anticipated expiration: 2023-12-11
Also published as: CN1546276A

Abstract

The invention discloses a crankshaft rolling strengthening process which comprises the following steps: adding a semi-fine grinding process after rough machining of the crankshaft, reserving fine grinding allowance in the radius direction of 0.15-0.30 mm, performing fillet rolling reinforcement after the semi-fine grinding process, wherein the rolling reduction of the fillet is more than 0.10mm, and then finely grinding the shaft neck to the size of a finished product. After the technical scheme is adopted, the flange during rolling can be eliminated during fine grinding, the requirement on radial run-out of the crankshaft after rolling is reduced, and the efficiency of the rolling process is improved; because proper accurate grinding allowance and rolling process parameters are selected, compared with a rolling process after accurate grinding, the bending fatigue strength of the crankshaft processed by the process is not reduced, and the traditional concept that the fatigue strength is obviously reduced because a rolling strengthening layer is ground after the crankshaft is semi-accurately ground and then is accurately ground is overcome.

Description

A kind of crankshaft rolling reinforcement process

Technical field: the invention belongs to internal combustion engine system technology for making field, relate in particular to a kind of crankshaft rolling reinforcement process.

Background technology: fillet rolling is bent axle one of the most effective intensifying method.It has production efficiency height, remarkable, the low cost and other advantages of strengthening effect, thereby is that domestic and international automobile engine crankshaft is produced generally employing of institute.

The domestic finished product roll extrusion that has commonly used of crankshaft rolling technology is cut roll extrusion with sinking.The finished product roll extrusion is to carry out fillet rolling after bent axle is worked into product size, and it does not change original processing technology and operation, but two shortcomings are arranged: the one, at axle journal and round-corner transition place the flange of extruding is arranged after the roll extrusion; The 2nd, the bent axle circular runout increases after the roll extrusion, can not satisfy product drawing and want, thereby the finished product rolling technology generally adopted when early stage, rolling technology development experiments and small lot were installed.It is heavy that to cut roll extrusion be to process a undercut groove at the crankshaft fillet place in advance, the finish rolling hardening position is in groove, can not destroy the roll extrusion layer during grinding axle journal, and roll extrusion flange and distortion in rolling have been eliminated, this technology reaches in the engine of introduction very universal abroad, but the requirement on machining accuracy height of undercut groove needs special purpose machine tool processing, and the costing an arm and a leg of special purpose machine tool, general enterprise is difficult to bear.In traditional idea, think that bent axle half finish grindes the back roll extrusion and finish grindes simultaneously, rolling strengthening layer can be ground off that fatigue strength can significantly reduce.

Summary of the invention: the present invention increases for bent axle circular runout after solving bent axle finished product roll extrusion axle journal and round-corner transition place the flange extruded, roll extrusion being arranged, the heavy simultaneously high problem of roll extrusion cost of cutting, a kind of crankshaft rolling reinforcement process is proposed: be after bent axle roughing, to increase half precision grinding process, radial direction is reserved mill surplus 0.15～0.30mm, behind half precision grinding process, carry out fillet rolling and reinforcing, the drafts of fillet rolling finish grindes axle journal then to finished size more than 0.10mm.

After adopting this process program, the flange in the time of can eliminating roll extrusion during correct grinding also requires to reduce to circular runout behind the crankshaft rolling, has improved rolling step efficient; Owing to select suitable correct grinding surplus and rolling technology parameter, bent axle through this processes, compare with correct grinding back rolling technology, crankshaft bending fatigue intensity does not descend, overcome bent axle half correct grinding back roll extrusion and finish grinded again, rolling strengthening layer can have been ground off, the significantly reduced traditional concept of fatigue strength.

The specific embodiment: the main technique flow process of this crankshaft rolling reinforcement process is: roughing → axle journal impewdance matching, tempering → half correct grinding → roll extrusion → rolling and straightening → correct grinding → polishing.Be to carry out half correct grinding behind the crankshaft journal impewdance matching earlier, radial direction is reserved the correct grinding surplus of 0.15～0.30mm, carry out fillet rolling and reinforcing and alignment then, the bent axle circular runout is controlled within the 0.18mm after the alignment, finish grindes, its operation of base such as polishing is to finished size again.Wherein the selection of rolling technology parameter is to determine by the method for engineer testing.

When adopting this scheme finish rolling hardening, crankshaft fillet has drafts, and generally more than 0.10mm, the stock removal of fillet is very little during correct grinding, simultaneously during finish rolling hardening the fillet residual compressive stress in inferior top layer maximum, even grind off a bit.The fillet maximum residual stress changes little, and 0.15～0.30mm correct grinding surplus that radial direction is reserved has just guaranteed this point; And the principal element that influences the crankshaft rolling strengthening effect is exactly the fillet residual compressive stress; For these reasons, use this technology, bent axle is carried out finish rolling hardening, do not reduce Crankshaft Fatigue Strength.Overcome bent axle half table correct grinding back roll extrusion row correct grinding again the time, rolling strengthening layer can have been ground off, fatigue strength can significantly reduced traditional concept.

Concrete case study on implementation is as follows: A type and Type B bent axle

Material: QT700-2, as cast condition;

Reinforcement process: half correct grinding back roll extrusion

Strengthening effect relatively sees Table 1:

Table 1 technology of the present invention and finished product finish rolling hardening effect contrast table

The bent axle model	Correct grinding back roll extrusion		Half correct grinding back roll extrusion
	Correct grinding back roll extrusion		Half correct grinding back roll extrusion		Fatigue strength (Nm)	Standard deviation (Nm)	Fatigue strength (Nm)	Standard deviation (Nm)
	The A type	1909	171.6	2000	Fatigue strength (Nm)	Standard deviation (Nm)	Fatigue strength (Nm)	Standard deviation (Nm)	105.0
Type B	The A type	1909	171.6	2000	2133	75.3	2130	83.7	105.0

Claims

1, a kind of crankshaft rolling reinforcement process, be to increase by half precision grinding process after bent axle roughing, radial direction is reserved correct grinding surplus 0.15～0.30mm, carries out fillet rolling and reinforcing behind half precision grinding process, the drafts of fillet rolling finish grindes axle journal then to finished size more than 0.10mm.