CN101920404A - Special welding electrode for surfacing and repairing broken teeth of cast iron gear - Google Patents

Abstract

The invention relates to a special welding electrode for surfacing and repairing broken teeth of a cast iron gear, belonging to the materials science and engineering field. The welding electrode comprises the following chemical components: 35-50wt% of marbles, 3-6wt% of chalk, 20-30wt% of fluorite, 1-3wt% of quartz, 2-4wt% of rutile, 4-7wt% of ferrotitanium, 2-5wt% of ferromolybdenum, 1-3wt% of high carbon ferromanganese, 1-3wt% of ferrosilicon, 4-7wt% of yttrium oxide and 10-14wt% of metallic nickel. The core wire is H08A steel welding wire. An adopted water glass binder has modulus of 2.7-3.0 and concentration (Baume degree) of 48-50. The surfacing welding electrode can be used for surfacing and repairing the broken teeth of the cast iron gear without preheating before welding and heat treatment after welding. The surfacing metal has higher crack resistance and has proper hardness (HB120-220) and abrasive resistance through alloying.

Description

Special welding electrode for surfacing and repairing broken teeth of cast iron gear

Technical field

The present invention relates to the Materials Science and Engineering field, particularly relate to a kind of cast iron gear broken teeth and repair build up electrode.

Background technology

Gear is one of most widely used part in the machine driving, for some underloadings, low speed, be not hit, precision and the less demanding inessential gear of compact conformation, casting pig manufacturing commonly used.The casting pig gear generally carries out stress relief annealing, normalizing after casting, quench in the machining rear surface, and purpose is to improve wearability.The casting pig gear is used for the exposed gear transmission more.In the enclosed transmission, adopt spheroidal graphite cast-iron to replace the trend of cast steel manufacturing gear increasing in recent years.Yet cast iron gear toughness is lower, is easy to produce under impact loading lost efficacy.

Gear-driven failure mode and influence factor are more, and wherein gear tooth fracture (broken teeth) is comparatively common gear destruction form, also is the major reason that causes gear failure.Modal in actual the use is overload broken teeth and two kinds of forms of tired broken teeth.

The overload broken teeth is to substantially exceed design load when real load, or seriously concentrates because of gear teeth loose contact causes load, makes the stress of the gear teeth surpass its limit stress, produces the phenomenon of the whole or local fracture of the gear teeth in a short time.

Tired broken teeth is that the gear teeth are being subjected under the too high alternate stress repeat function for a long time, the position generation fatigue crack that root bending stress is big and stress is concentrated relatively at the gear teeth, along with the effect increased frequency, original fatigue crack is constantly expanded, when the stress on the tooth root remaining cross-section surpassed its limit stress, the gear teeth will cause broken teeth because of overload.

In addition, comparatively common also have broken teeth at random.Broken teeth is meant the broken teeth that fortuitous event causes at random, as foreign matter enter, insufficient lubrication, fault in material, mill are scraped crackle, the heat treatment residual stress is crossed the break of gear tooth phenomenon that high reason causes.

Though the cast iron gear low price, its use amount is bigger, and particularly broken teeth is generally accident, is not having under the situation of equipment gear, and broken teeth can seriously influence normal production, brings enormous economic loss to enterprise.Therefore, under the situation that technical conditions allow, gear tooth breakage is carried out the built-up welding reparation, both met the requirement of " green manufacturing ", can directly create economic benefit again for enterprise.

Yet, in cast iron gear broken teeth built-up welding repair process, be easy to generate and organize air chill and problems such as crackle occur; Adopt traditional surfacing welding, though before weldering to cast iron gear preheating (about 400 ℃), and under the postwelding condition of heat-treating, deposited metal and heat affected zone cracking tendency are still very big.Simultaneously, weld preheating, post weld heat treatment will be wasted a large amount of energy, make welding procedure complicated, and increase working strength of workers, cause sizable economic loss to enterprise.

Summary of the invention

In order to realize that the cast iron gear broken teeth is carried out the built-up welding reparation, invented a kind of build up electrode of using.The characteristics of this welding rod are need not carry out preheating to cast iron gear before the weldering, and postwelding need not be heat-treated, and on-the-spot very easy to use, hardness range is HB120-220, is suitable for processing after the cast iron gear built-up welding.

Thisly be used to repair broken teeth cast iron gear build up electrode and it is characterized in that marble 35-50, chalk 3-6, fluorite 20-30, quartzy 1-3, rutile 2-4, ferrotianium 4-7, molybdenum-iron 2-5, high carbon ferromanganese 1-3, ferrosilicon 1-3, yittrium oxide 4-7, metallic nickel 10-14.Core wire is a H08A steel welding wire.The modulus of the water glass of binder that adopts is 2.7-3.0, and concentration (Baume degrees) is 48-50.For needing to carry out Passivation Treatment before ferrosilicon and the high carbon ferromanganese use, the passivation technology silicon iron powder is 720-750 ℃, and the high carbon ferromanganese powder is 300-350 ℃, and above metal dust all is incubated 1 hour.

The principle of this surfacing welding design is the service condition according to cast iron gear, though the working gear condition is underloading, low speed, is not hit, its precision and compact conformation are less demanding, but, require to have higher anti-cracking performance in the weld deposit process, postwelding also should have certain machinability simultaneously.In earlier stage the result of study of developing the cast iron gear surfacing welding according to this seminar shows, consider from the anti-cracking performance angle that improves deposited metal, the built-up welding meeting makes the heat affected area of cast iron gear organize air chill, the existence form of carbon becomes carbide for fragility by the graphite of toughness, make the heat affected area have bigger residual tension, thereby increased the tearing tendency of deposited metal; Can improve stabilization of austenite in the deposited metal and add nickel, increase remained austenite content, the residual tension of the heat affected area that can relax simultaneously, improves the moulding of deposited metal, toughness; Adding rare earth oxide can deoxidation, desulfurization, purifies the built-up welding molten bath, and crystallization of refinement crystal grain, and rotten field trash can improve the anti-cracking performance of deposited metal; Studies show that the effect of yittrium oxide is the most obvious in the rare earth oxide.1), add the metal nickel powder of more amount so the design principle of novel cast iron surfacing welding is:,, improve the residual stress distribution state to improve the built-up welding tissue; 2), add an amount of rare earth oxide, improving the postwelding crystalline structure, rotten field trash, thereby improve the anti-cracking performance 3 of deposited metal), add an amount of molybdenum-iron, guarantee that deposited metal has certain competency.4), add an amount of ferrotianium, ferromanganese and ferrosilicon, carry out deoxidation, and play alloying action; 5), add rutile, marble, fluorite, chalk etc. and play slag making, degasification.By composition adjustment and optimization, the hardness that makes deposited metal has guaranteed that the cast iron gear after the built-up welding has certain machinability about HB120-220.

Compare with built-up welding hot roll, hot-shear blade and cold shear welding rod (having declared patent) that this seminar develops, cast iron gear hardness is lower, so need not add graphite (carbon), high carbon ferro-chrome (chromium), ferrotungsten (tungsten) etc. in the electrode coating, and the easy spoken parts in traditional operas that produces after the cast iron built-up welding, anti-cracking performance is relatively poor, so, added more nickel (10-14wt%) among the present invention.Compare with the built-up welding large gear welding rod (having declared patent) that this seminar develops, large gear hardness slightly high (HRC21-30), so in its electrode coating, add a spot of high carbon ferro-chrome (chromium), and its anti-cracking performance of cast iron built-up welding is relatively poor, so the metallic nickel (10-14wt%) that adds is more than the metallic nickel (3-5wt%) of built-up welding large gear welding rod; Simultaneously, add the better yittrium oxide of modification effect, rather than the cerium mixed oxide.As for add an amount of ferrotianium, ferromanganese, ferrosilicon, rutile, marble, fluorite, chalk etc. act in the serial surfacing welding prescription of this seminar development identical, so the addition of these raw materials is close in various surfacing weldings.

The specific embodiment

Openly be an example of the present invention below, require: marble 37.4, chalk 3.5, fluorite 22.7, quartz 1.7, rutile 3.8, ferrotianium 5.8, molybdenum-iron 2.6, high carbon ferromanganese 2.5, ferrosilicon 1.6, yittrium oxide 5.3, metallic nickel 13.1.Core wire adopts H08A steel welding wire.The modulus of the water glass of binder that adopts is 2.7-3.0, and concentration (Baume degrees) is 48-50.For needing to carry out Passivation Treatment before ferrosilicon and the high carbon ferromanganese use, the passivation technology silicon iron powder is 730 ℃, and the high carbon ferromanganese powder is 320 ℃, and above metal dust all is incubated 1 hour.Adopt batch mixer to mix in the relevant powder in the above-mentioned prescription, add waterglass then and stir, squeeze out welding rod, welding rod is dried, carry out bistrique mill tail then at 250-300 ℃ with the welding rod coating machine.

The HT200 cast iron gear broken teeth that the surfacing welding that adopts above-mentioned manufacturing uses North China Oilfield carries out the built-up welding reparation, before the weldering to welding rod 200-300 ℃ of oven dry 1 hour, remove the crystallization water in the coating, use DC welder, carry out reversal connection, welding current is 150-200A, and weldingvoltage is 70-80V.Before welding, need not carry out preheating to cast iron gear, postwelding need not be heat-treated, the hardness of the cast iron gear flank of tooth by the built-up welding reparation is HB170-200, after processing, can replace cast iron gear through monoblock cast production, not only reduced manufacturing process, saved the raw material and the energy, also improved service life simultaneously.

Adopt surfacing welding of the present invention that the cast iron gear broken teeth is carried out the built-up welding reparation, reduced energy resource consumption, avoided the pollution of manufacture process environment; By exempting from preheating, exempting from the heat treatment built-up welding and make the cast iron gear of scrapping recover original shape and size, and improved its service life, this difficult problem is repaired in all trades and professions institute ubiquitous cast iron gear broken teeth built-up welding such as solution China metallurgical machinery, mining machinery, agricultural machinery, Petro-Chemical Machinery have the important engineering meaning, its market space is very wide.

Claims (2)

1. one kind is used for cast iron gear broken teeth reparation build up electrode, and its chemical composition is (wt%): marble 35-50, chalk 3-6, fluorite 20-30, quartzy 1-3, rutile 2-4, ferrotianium 4-7, molybdenum-iron 2-5, high carbon ferromanganese 1-3, ferrosilicon 1-3, yittrium oxide 4-7, metallic nickel 10-14.Core wire is a H08A steel welding wire.The modulus of the water glass of binder that adopts is 2.7-3.0, and concentration (Baume degrees) is 48-50.

2. the rare earth oxide of Jia Ruing is a yittrium oxide.