CN104400344A - Bolt manufacturing technology - Google Patents

Abstract

The invention provides a bolt manufacturing technology which comprises the following steps of selecting materials, hot-rolling a coil rod, spheroidizing annealing, performing mechanical descaling, performing acid pickling, performing cold drawing, performing cold forging forming, performing thread machining, performing heat treatment and testing, wherein the materials comprises, by weight, 0.25-0.55% of C, 0.45-0.80% of Mn, smaller than or equal to 0.30% of Si, smaller than or equal to 0.030% of P, smaller than or equal to 0.035% of S and the largest value of 0.005% of B, and the steel softening annealing temperature is 715-770 degree centigrade. The bolt manufacturing technology is suitable for manufacturing mass bolts, and the manufacturing technology enables the bolts to be high in structural strength and strong in toughness.

Description

A kind of screw bolt manufacture process

Technical field

The present invention relates to a kind of screw bolt manufacture process, belong to machinery manufacturing technology field.

Background technology

The nut of existing bolt can adopt cold pier or hot pier technique the method to save material, selects the method for pier according to pier forging machine tonnage size and the diameter of bolt.The turret head of the special or special bolts of small lot is that after turning, milling becomes.Single and mini-batch production can use the method such as threading die mantle fiber, lathe Pick Wire, whirling mill milling.Shank of bolt manufacturing process has cold-drawn and undergauge, so this bolt does not have threaded section diameter not necessarily smaller.When adopting cold-drawn, smaller; When adopting undergauge, can be isometrical or slightly large with screw thread.Bolt material is alloy or the metal of the low melting points such as aluminium alloy, kirsite, copper alloy, also can adopt the method for die cast.Above-described processing method is all suitable for the bolt manufacture of small lot, and is not very applicable for large batch of bolt manufacture.

Summary of the invention

The invention provides a kind of screw bolt manufacture process, be particularly useful for large batch of bolt manufacture, and the bolt quality produced is good, structural strength is high, good toughness.

For solving above technical problem, the invention provides following technical scheme: a kind of screw bolt manufacture process, comprising the steps: selection-gren rod-spheroidizing-mechanical descaling-pickling-cold group-cold-forging forming-screw thread process-heat treatment-inspection; Selection: C content to be 0.25%-0.55%, Mn be 0.45%-0.80%, Si is less than or equal to 0.30%, P and is less than or equal to 0.030%, S to be less than or equal to 0.035%, B maximum be 0.005%; Wherein, steel softening annealing temperature is 715-770 degree Celsius, isothermal temperature 680-700 degree Celsius; De-scaling comprises bending method and spray nine methods, and wherein bending method is the circle wheel alternating bending wire rod using band triangular groove, forms compound de-scaling after dephosphorization through chemical pickling; The draft value of cold-drawn controls in the scope of 10%-15%; In screw thread process, the shaping of bolt head adopts cold-heading plastic working, and metallic fiber is sequential like along shape of product, and middle without cutting off, blank delivers to jumping-up shaping station after cutting off; Bolt thread adopts cold working, makes threaded blank within the scope of certain diameter by screw plate, makes screw forming by filament plate pressure; Heat treatment bolt, from material loading-cleaning-heating-quenching-cleaning-tempering-painted to rolling off the production line, all adopting and automatically controlling.

This screw bolt manufacture process that the present invention relates to, be applicable to the manufacture of bolt in enormous quantities, manufacturing process makes the structural strength of bolt high, and toughness is strong.

Detailed description of the invention

A kind of screw bolt manufacture process, comprises the steps: selection-gren rod-spheroidizing-mechanical descaling-pickling-cold group-cold-forging forming-screw thread process-heat treatment-inspection; Selection: C content to be 0.25%-0.55%, Mn be 0.45%-0.80%, Si is less than or equal to 0.30%, P and is less than or equal to 0.030%, S to be less than or equal to 0.035%, B maximum be 0.005%; Wherein, steel softening annealing temperature is 715-770 degree Celsius, isothermal temperature 680-700 degree Celsius; De-scaling comprises bending method and spray nine methods, and wherein bending method is the circle wheel alternating bending wire rod using band triangular groove, forms compound de-scaling after dephosphorization through chemical pickling; The draft value of cold-drawn controls in the scope of 10%-15%; In screw thread process, the shaping of bolt head adopts cold-heading plastic working, and metallic fiber is sequential like along shape of product, and middle without cutting off, blank delivers to jumping-up shaping station after cutting off; Bolt thread adopts cold working, makes threaded blank within the scope of certain diameter by screw plate, makes screw forming by filament plate pressure; Heat treatment bolt, from material loading-cleaning-heating-quenching-cleaning-tempering-painted to rolling off the production line, all adopting and automatically controlling.

Bolt all will carry out modifier treatment according to technical requirement.Heat treatment quenching and tempering is the comprehensive mechanical performance in order to improve bolt, to meet the tensile strength values and yield tensile ratio that product specifies.Technology for Heating Processing has vital impact to bolt especially its inherent quality, therefore, wants the bolt producing high-quality, must have advanced heat treatment technics equipment.Because bolt output is large, cheap, threaded portion is again the structure of thinner microfacies to precision, and therefore, require that Equipment for Heating Processing must possess production capacity large, automaticity is high, the ability that thermal treatment quality is good.Shake end type net belt furnace is particularly useful for the heat treatment quenching and tempering of medium and small sized bolt.Modified line, except stove good seal performance, also has advanced atmosphere, and temperature and technological parameter computer control, device failure alert and Presentation Function.Bolt is from material loading-cleaning-heating-quenching-cleaning-tempering-painted to rolling off the production line, and whole auto-controll operation, effectively ensure that thermal treatment quality.The decarburization of screw thread can cause bolt first to be threaded off when not reaching the drag of mechanical property requirements, screw bolt is lost efficacy, reduction of service life.Due to the decarburization of raw material, if it is improper to anneal, raw material decarburized layer more can be made to deepen.In Tempering and Quenching process, generally to come in addition some oxidizing gases from stove.Residue after the iron rust of bar steel wire or cold-drawn in wire rod Steel Wire Surface, also can decompose after entering stove heating, reaction generates some oxidizing gas.Such as, the surperficial iron rust of steel wire, its composition is ferric carbonate and hydroxide, will resolve into CO2 and H2O after the heating, thus increase the weight of decarburization.Comparatively carbon steel is serious for the decarbonization degree of medium carbon alloy steel, and the fastest decarburization temperature is between 700-800 degree Celsius.It is very fast that attachment due to Steel Wire Surface decomposes the speed of being combined to CO2 and H2O under certain condition, if the control of grill-hearth travelling oven furnace gas is improper, screw decarburization also can be caused overproof.Bolt is when adopting cold upset forming, and not but still exist, and be extruded to the top of screw thread, for the bolt surface needing quenching, can not get required hardness, its mechanical performance (particularly intensity and wearability) does not reduce the decarburized layer of raw material and annealing.In addition, Steel Wire Surface decarburization, top layer is different from interior tissue and have the different coefficients of expansion, likely produces face crack during quenching.For this reason; threaded top not decarburization to be protected when Quench heating; also will to the bolt of raw material decarburization carry out appropriateness cover carbon; the original phosphorus content of the part advantage of the protective atmosphere in meshbeltfurnace being transferred to and being coated to carbon is substantially equal, and make the bolt of decarburization slowly return to original phosphorus content, carbon potential is set in 0.42%-0.48% and is advisable; cover carbon temperature identical with Quench heating; at high temperature can not carry out, in order to avoid coarse grains, affect mechanical performance.

Detailed description of the invention of the present invention does not form the restriction to the application's scope; within every spirit in the present invention's design and principle, any amendment that one of skill in the art can make, equivalent to replace and improvement etc. all should be included within protection scope of the present invention.

Claims (1)

1. a screw bolt manufacture process, is characterized in that: comprise the steps: selection-gren rod-spheroidizing-mechanical descaling-pickling-cold group-cold-forging forming-screw thread process-heat treatment-inspection; Selection: C content to be 0.25%-0.55%, Mn be 0.45%-0.80%, Si is less than or equal to 0.30%, P and is less than or equal to 0.030%, S to be less than or equal to 0.035%, B maximum be 0.005%; Wherein, steel softening annealing temperature is 715-770 degree Celsius, isothermal temperature 680-700 degree Celsius; De-scaling comprises bending method and spray nine methods, and wherein bending method is the circle wheel alternating bending wire rod using band triangular groove, forms compound de-scaling after dephosphorization through chemical pickling; The draft value of cold-drawn controls in the scope of 10%-15%; In screw thread process, the shaping of bolt head adopts cold-heading plastic working, and metallic fiber is sequential like along shape of product, and middle without cutting off, blank delivers to jumping-up shaping station after cutting off; Bolt thread adopts cold working, makes threaded blank within the scope of certain diameter by screw plate, makes screw forming by filament plate pressure; Heat treatment bolt, from material loading-cleaning-heating-quenching-cleaning-tempering-painted to rolling off the production line, all adopting and automatically controlling.