CN101445867A - Heat treatment method for high-power locomotive diesel engine crankshafts - Google Patents

Abstract

A heat treatment method for high-power locomotive diesel engine crankshafts comprises the following steps: the crankshafts are placed in a heat treatment well type heating furnace and preheated to a temperature of 400 to 500 DEG C, and the heat of the crankshafts is preserved for 1 to 3 hours; the preheated crankshafts are lifted out and horizontally placed on a support frame; a lacing wire is welded between each pair of crankshafts; the material of the lacing wire is Q235A, the welding current is 140A, and the name of the welding rod is R317; the welded crankshafts are laid in the heat treatment well type heating furnace and preheated to a temperature of 400 to 500 DEG C, and the heat of the crankshafts is preserved for 1 to 3 hours; the crankshafts reach a uniform temperature of 600 to 700 DEG C, and the heat is preserved for 1 to 3 hours; the crankshafts are heated to 800 to 900 DEG C, and the heat is preserved for 6 to 8 hours; quenching is conducted, and then tempering is conducted; the crankshafts reach a temperature of 400 to 500 DEG C, and the heat is preserved for 1 to 3 hours; the crankshafts is heated to a temperature of 520 to 620 DEG C, and the heat is preserved for 8 to 10 hours; and the lacing wire is cut off. The method has the advantages of simple device, easy operation, low processing cost, and easy control of errors. Furthermore, the method saves time and labor.

Description

Heat treatment method for high-power locomotive diesel engine crankshafts

Technical field

The present invention relates to a kind of heat treating method, particularly a kind of heat treatment method for high-power locomotive diesel engine crankshafts.

Background technology

High-power locomotive diesel engine crankshafts absolutely produces distortion after modified quenching, wherein some bending is beated overproofly, and this is the technical barrier of most critical during bent axle is made.The bending overproof aligning method commonly used of beating is: support crankshaft two end with v block,, be pressed in position intermediate with pressure with axial height point up, intensified pressure up to producing viscous deformation, reduces jerk value gradually, reaches qualified purpose.With 50CrMo4 steel (HB295-355) is example, yield strength Rel ≈ 700 at normal temperatures, stress measurement shows, have only when bent axle is bent to the 7mm left and right sides down, could produce the amount of recovery of beating, if with of the bent axle alignment of modified quenching after strain amount at 10 millimeters, must need large-tonnage straightener and complicated frock, investment is big, complicated operation, and quality is restive; And, also need carry out the destressing ageing treatment after the alignment, the production cycle is long.

Summary of the invention

The purpose of this invention is to provide simple, the good operation of a kind of equipment, time saving and energy saving, tooling cost is low, control error is easy to heat treatment method for high-power locomotive diesel engine crankshafts, overcomes the deficiencies in the prior art.

Heat treatment method for high-power locomotive diesel engine crankshafts of the present invention is characterized in that: it comprises the steps:

A, bent axle was placed heat treatment well type heating furnace, is preheating to 400 ℃--500 ℃, being incubated 1 hour--3 hours;

B, hang out and lie in a horizontal plane in the bent axle of preheating on the bracing frame;

C, between every pair of crank, weld lacing wire; The lacing wire material is Q235A, welding current 140A, the welding rod R317 trade mark;

D, the bent axle after welding finished place heat treatment well type heating furnace, 400 ℃--500 ℃ of preheatings are incubated 1 hour--3 hours; 600 ℃--700 ℃ of sammings are incubated 1 hour--and 3 hours; 800 ℃--900 ℃ of heating are incubated 6 hours--and 8 hours; Carry out modified quenching afterwards, the back tempering of quenching, 400 ℃--500 ℃ of sammings are incubated 1 hour--3 hours; 520 ℃--620 ℃ of heating are incubated 8 hours--and 10 hours;

E, cut away lacing wire.

The present invention compared with prior art, have simple, the good operation of equipment, time saving and energy saving, tooling cost is low, control error is easy to advantage.

Description of drawings

Fig. 1 is the structural representation of crank and lacing wire among the present invention.

Embodiment

With 280 diesel engine forged steel crankshafts (material is 42CrMo) is example:

The first step: bent axle is hung in the heat treatment well type heating furnace, be preheating to 400 ℃ or 450 ℃ or 500 ℃, be incubated 1 hour or 2 hours or 3 hours.

Second step: the bent axle of preheating hung out lie in a horizontal plane on the bracing frame.Wherein at least one set of bell cranks up.

The 3rd step: 2 lacing wires 2 evenly are placed on the crank 1, and with lacing wire 2 and crank 1 welding (as shown in Figure 1), every set of bell cranks 1 all adopts aforesaid way to handle.

The 4th one: bent axle is hung in the heat treatment well type heating furnace immediately, carry out modified quenching.

Modified quenching technology: 400 ℃ or 450 ℃ or 500 ℃ of preheatings are incubated 1 hour or 2 hours or 3 hours; 600 ℃ or 650 ℃ or 700 ℃ of sammings are incubated 1 hour or 2 hours or 3 hours; 800 ℃ or 850 ℃ or 900 ℃ of heating are incubated 6 hours or 7 hours or 8 hours; Modified tempering process quenches: 400 ℃ or 450 ℃ of 500 ℃ of sammings are incubated 1 hour or 2 hours or 3 hours; 520 ℃ or 570 ℃ or 620 ℃ of heating are incubated 8 hours or 9 hours 10 hours; Air cooling.

Mechanical property detects on request and lacing wire is cut away after qualified after the tempering, measures its deflection and is minimum 2.5 millimeters, maximum 7.5 millimeters.

Claims (1)

1, a kind of heat treatment method for high-power locomotive diesel engine crankshafts, it is characterized in that: it comprises the steps:

A, bent axle was placed heat treatment well type heating furnace, is preheating to 400 ℃--500 ℃, being incubated 1 hour--3 hours;

B, hang out and lie in a horizontal plane in the bent axle of preheating on the bracing frame;

C, between every pair of crank, weld lacing wire; The lacing wire material is Q235A, welding current 140A, the welding rod R317 trade mark;

D, the bent axle after welding finished place heat treatment well type heating furnace, 400 ℃--500 ℃ of preheatings are incubated 1 hour--3 hours; 600 ℃--700 ℃ of sammings are incubated 1 hour--and 3 hours; 800 ℃--900 ℃ of heating are incubated 6 hours--and 8 hours; Carry out modified quenching afterwards, the back tempering of quenching, 400 ℃--500 ℃ of sammings are incubated 1 hour--3 hours; 520 ℃--620 ℃ of heating are incubated 8 hours--and 10 hours;

E, cut away lacing wire.