CN103084524A - Method for forging flange bolt - Google Patents

Abstract

The invention discloses a method for forging a flange bolt. The method comprises the following machining steps of: (a) manufacturing a rod blank by a casting process, wherein the rod blank comprises the following chemical ingredients in percentage by weight: 0.25 to 0.35 percent of C, 0.15 to 0.25 percent of Mn, 0.15 to 0.35 percent of Si, 0.01 to 0.04 percent of W, less than or equal to 0.025 and more than or equal to 0.015 percent of P, less than or equal to 0.035 and more than or equal to 0.015 percent of S, 0.15 to 0.20 percent of Ni, 0.025 to 0.045 percent of Ba, 0.02 to 0.03 percent of Sn, less than or equal to 0.02 percent of Mg and the balance of Fe; and (b) casting a cast rod for forming, forging at the temperature of between 600 and 650 DEG C for less than or equal to 25 times, covering thin-layer plant ash on the inner wall of a die cavity of a forging die, and turning the forged rod by utilizing a precision lathe to form external threads of the bolt, wherein the granularity of the plant ash is 200 to 300 meshes. According to the method for forging the flange bolt, the bolt is machined by using a cold extrusion process, so that the strength of the bolt is enhanced, a hardness value and a strength value which are required by the high-strength bolt of which the strength is 12.9 are reached, and the delayed breakage and fatigue breakage of the bolt under high strength are avoided; and the flange bolt is reliable in connection and difficult to break in the using process, so that the service life of the bolt is prolonged, and the using requirement of each industry in society on the high-strength bolt is met.

Description

The flange bolt forging method

Technical field

The present invention relates to the processing method of bolt, especially a kind of flange bolt forging method.

Background technology

Flange bolt is securing member commonly used in machinery industry, and present processing mode is generally the moulding of turning, and intensity often is difficult to guarantee, sometimes in use produce turn around, the dangerous phenomenon such as bar section fracture, endanger very large to industrial production.Therefore the high-strength bolt production method is studied and improved, guaranteed the quality stability of flange bolt, technology and expanding economy are had important function.In addition, when bolt was in relatively moist environment, the corrosion that gets rusty easily finally caused fracture or crackle, forms potential accident source.

Given this, be necessary to provide a kind of processing method of flange bolt, the better bolt of manufacturing machine performance.

Summary of the invention

The object of the invention is to avoid weak point of the prior art, and a kind of flange bolt forging method is provided.

Purpose of the present invention is as follows by the following technical programs:

The flange bolt forging method, procedure of processing comprises:

A, make bar material blank by casting technique, the percentage by weight of each chemical composition of control lever material blank should satisfy following requirement: C 0.25～0.35, Mn 0.15～0.25, Si 0.15～0.35, W 0.01-0.04,0.015≤P≤0.025,0.015≤S≤0.035, Ni 0.15～0.20, Ba 0.025～0.045, Sn 0.02～0.03, Mg≤0.02, and surplus is iron;

B, the bar material after casting is carried out forging and molding processing, forge temperature and be controlled to be 600-650 ℃, forging covering thin layer plant ash on the impression inwall of mould, the granularity of plant ash is controlled to be the 200-300 order, forge number of times no more than 25 times, utilize fine turning lathe turning to go out the bolt external screw thread after forging moulding;

C, heat treatment, that the bolt external screw thread after turning was heated 8-9 hour under 460-550 ℃ for the first time, be warming up to 1080-1120 ℃ in 20-30 minute again, keep 20 minutes heat time heating times, quench with quenching oil, bolt after quenching again carries out tempering and kept 30 minutes under 500 ℃, then takes out from tempering furnace and put into 300-320 ℃ of No. 200 solvent naphthas with oily slow cooling; Be for the second time bolt head with bolt under 800 ℃ ± 20 ℃, the use quenching liquid quenches, then the bolt after quenching carries out tempering, 60 minutes duration under 600 ℃;

D, the bolt after heat treatment is carried out subzero treatment, liquid nitrogen temperature is-125～-150 ℃, and the time of subzero treatment is 2-5 hour, and the isothermal time in liquid nitrogen is: the cross-sectional area of bolt multiply by 2～3min/mm ², the bolt that after subzero treatment, temperature has been gone back up to room temperature is put into boiling water heating 60-80 minute of 100 ℃;

E, blackening process, be under the condition of 120～130 ℃ in temperature, bolt is placed in to process in sodium nitrite solution is grey black or all black to the surface, then bolt is taken out from sodium nitrite solution, and spontaneous curing 15～20min, more fully clean, obtain the finished product bolt after air-dry with water.

Flange bolt forging method of the present invention, adopt the processing of cold-extrusion technology bolt, improved the intensity of bolt, reached required hardness number, the intensity level of 12.9 high-strength bolts, solved delayed fracture and the fatigue fracture of bolt under high strength, in use connected reliably, not frangibility, improve bolt life, satisfied social upper every profession and trade to the user demand of high-strength bolt.

Beneficial effect of the present invention is:

1, refinement of the present invention the shaping processing technology of material, make wire rod hardness moderate, the surface has good phosphatization epithelium, greasy property is good, wire rod is without hydrogen embrittlement, plasticity is good;

2, bolt of the present invention has carried out the processing of multi-step, has improved the flange bolt bulk strength, and the bolt precision is high, and quality is good, and production efficiency is high, and without waste material, unit cost descends greatly without cutting.Obtain bulk metal and flowed to the consistent bolt of direction, greatly improved its tensile strength;

3, the invention of Technology for Heating Processing has broken through the limit of the alloy steel products of bolt prior heat treatment, the leading domestic Investment in fastener industry level of the characteristic of its super-strong and super-toughened property.

The specific embodiment

The invention will be further described with the following Examples:

The flange bolt forging method, procedure of processing comprises:

A, make bar material blank by casting technique, the percentage by weight of each chemical composition of control lever material blank should satisfy following requirement: C 0.25～0.35, Mn 0.15～0.25, Si 0.15～0.35, W 0.01-0.04,0.015≤P≤0.025,0.015≤S≤0.035, Ni 0.15～0.20, Ba 0.025～0.045, Sn 0.02～0.03, Mg≤0.02, and surplus is iron;

B, the bar material after casting is carried out forging and molding processing, forge temperature and be controlled to be 600-650 ℃, forging covering thin layer plant ash on the impression inwall of mould, the granularity of plant ash is controlled to be the 200-300 order, forge number of times no more than 25 times, utilize fine turning lathe turning to go out the bolt external screw thread after forging moulding;

C, heat treatment, that the bolt external screw thread after turning was heated 8-9 hour under 460-550 ℃ for the first time, be warming up to 1080-1120 ℃ in 20-30 minute again, keep 20 minutes heat time heating times, quench with quenching oil, bolt after quenching again carries out tempering and kept 30 minutes under 500 ℃, then takes out from tempering furnace and put into 300-320 ℃ of No. 200 solvent naphthas with oily slow cooling; Be for the second time bolt head with bolt under 800 ℃ ± 20 ℃, the use quenching liquid quenches, then the bolt after quenching carries out tempering, 60 minutes duration under 600 ℃;

D, the bolt after heat treatment is carried out subzero treatment, liquid nitrogen temperature is-125～-150 ℃, and the time of subzero treatment is 2-5 hour, and the isothermal time in liquid nitrogen is: the cross-sectional area of bolt multiply by 2～3min/mm ², the bolt that after subzero treatment, temperature has been gone back up to room temperature is put into boiling water heating 60-80 minute of 100 ℃;

E, blackening process, be under the condition of 120～130 ℃ in temperature, bolt is placed in to process in sodium nitrite solution is grey black or all black to the surface, then bolt is taken out from sodium nitrite solution, and spontaneous curing 15～20min, more fully clean, obtain the finished product bolt after air-dry with water.

The bolt of producing according to the preparation method of flange bolt of the present invention, as follows through detecting its mechanical performance numerical value of test, the bolt centre hardness reaches 40-43HRC, bolt thread section hardness reaches 38-40HRC, shear strength reaches 900Mpa, yield strength reaches 1000Mpa, percentage elongation is greater than 10%, and the contraction percentage of area is greater than 35%, and impact flexibility is greater than 56J/cm ², the high 10-12% of bolt that comprehensive mechanical performance produces than existing technique.

Should be noted that at last; above embodiment only is used for technical scheme of the present invention being described but not limiting the scope of the invention; although with reference to preferred embodiment, the present invention has been done detailed description; those of ordinary skill in the art is to be understood that; can modify or be equal to replacement technical scheme of the present invention, and not break away from essence and the scope of technical solution of the present invention.

Claims (1)

1. the flange bolt forging method, is characterized in that, procedure of processing comprises:

A, make bar material blank by casting technique, the percentage by weight of each chemical composition of control lever material blank should satisfy following requirement: C 0.25～0.35, Mn 0.15～0.25, Si 0.15～0.35, W 0.01-0.04,0.015≤P≤0.025,0.015≤S≤0.035, Ni 0.15～0.20, Ba 0.025～0.045, Sn 0.02～0.03, Mg≤0.02, and surplus is iron;

B, the bar material after casting is carried out forging and molding processing, forge temperature and be controlled to be 600-650 ℃, forging covering thin layer plant ash on the impression inwall of mould, the granularity of plant ash is controlled to be the 200-300 order, forge number of times no more than 25 times, utilize fine turning lathe turning to go out the bolt external screw thread after forging moulding;

C, heat treatment, that the bolt external screw thread after turning was heated 8-9 hour under 460-550 ℃ for the first time, be warming up to 1080-1120 ℃ in 20-30 minute again, keep 20 minutes heat time heating times, quench with quenching oil, bolt after quenching again carries out tempering and kept 30 minutes under 500 ℃, then takes out from tempering furnace and put into 300-320 ℃ of No. 200 solvent naphthas with oily slow cooling; Be for the second time bolt head with bolt under 800 ℃ ± 20 ℃, the use quenching liquid quenches, then the bolt after quenching carries out tempering, 60 minutes duration under 600 ℃;

D, the bolt after heat treatment is carried out subzero treatment, liquid nitrogen temperature is-125～-150 ℃, and the time of subzero treatment is 2-5 hour, and the isothermal time in liquid nitrogen is: the cross-sectional area of bolt multiply by 2～3min/mm ², the bolt that after subzero treatment, temperature has been gone back up to room temperature is put into boiling water heating 60-80 minute of 100 ℃;

E, blackening process, be under the condition of 120～130 ℃ in temperature, bolt is placed in to process in sodium nitrite solution is grey black or all black to the surface, then bolt is taken out from sodium nitrite solution, and spontaneous curing 15～20min, more fully clean, obtain the finished product bolt after air-dry with water.