阅读说明：本技术 渗碳直顶杆产品加工方法 (method for processing carburized straight ejector rod product ) 是由 贾东霞 宁甲明 王克 孙汉新 于连鹏 任洪亮 王爱臣 金波 于 2019-08-26 设计创作，主要内容包括：本发明涉及渗碳直顶杆产品加工方法,本发明首先对合金钢原材料进行表面渗碳处理工艺,其次将渗碳合金钢热处理加工,最后进行渗碳合金钢顶杆加工得到高韧性、高硬度且均匀、低不良率的直顶杆。该方法简单易推广,有效降低成本,解决了目前渗氮层硬度虽高但渗层较浅,氮化硬度不均匀、产品弯曲畸变的现象。(The invention relates to a method for processing a carburized straight ejector rod product, which comprises the steps of firstly carrying out surface carburization treatment on alloy steel raw materials, secondly carrying out heat treatment on carburized alloy steel, and finally carrying out carburized alloy steel ejector rod processing to obtain the straight ejector rod with high toughness, high hardness, uniformity and low fraction defective. The method is simple and easy to popularize, effectively reduces the cost, and solves the problems of high hardness of the nitriding layer, shallow nitriding layer, uneven nitriding hardness and bending distortion of the product in the prior art.)

1. The processing method of the carburized straight ejector rod product is characterized by comprising the following steps of:

S1, firstly, carrying out a surface carburization treatment process on an alloy steel raw material, wherein the alloy tool steel raw material comprises 0.35-0.45% of carbon element, 0.8-1.2% of silicon element, 0.3-0.5% of manganese element, less than or equal to 0.03% of phosphorus element, less than or equal to 0.02% of sulfur element, 5.0-5.5% of chromium element, 1.3-1.6% of molybdenum element, 1.0-1.25% of vanadium element and the balance of iron element;

s2, carrying out heat treatment on the carburized alloy steel;

S3, processing of carburized alloy steel ejector rod

S3.1 nitriding: cleaning the surface of carburized alloy steel, then charging, sealing a furnace cover, heating to 420 +/-10 ℃, introducing ammonia gas, controlling the flow of the ammonia gas to be 2-3 MPa/h, continuously heating, introducing for 0.5-1h, heating to 530 +/-10 ℃, increasing the pressure of the ammonia gas to 3-4 MPa/h, entering a heat preservation state, preserving heat for 2-2.5h, reducing the pressure of the ammonia gas to 1.5 MPa/h, preserving heat for 3-4h, closing the ammonia gas, cooling to below 300 ℃, and discharging;

S3.2, after the straight strip carburized alloy steel is cut into short rods with corresponding specifications, the processes of fine grinding, upsetting, head forming and polishing are sequentially carried out.

2. The processing method according to claim 1, wherein the step S1 includes the following steps:

s1.1, raising the temperature of a furnace to 800 +/-10 ℃, placing a disc-shaped alloy tool steel raw material to be treated into a carburizing periodic furnace, closing a furnace cover, raising the temperature to 930 +/-10 ℃, dropping kerosene into the furnace at a speed of 160 drops per minute in the process of raising the temperature, and exhausting gas for 60-80 minutes generally;

S1.2, judging a strong permeation time point, increasing the dropping amount of kerosene during strong permeation, putting a test bar during strong permeation according to 180-200 drops per minute, wherein the carburizing speed is 0.15-0.2 mm/h, and when the depth of an upper permeation layer of the test bar reaches one half, the next diffusion period can be carried out after the strong permeation is finished;

S1.3, keeping the temperature unchanged in a diffusion period, reducing the kerosene drop amount, and controlling the diffusion time to be 60-90 minutes according to 100 drops per minute;

S1.4, starting cooling after the diffusion period is ended, cooling to 810 +/-10 ℃, preserving heat for 10-20 minutes at the temperature, reducing the kerosene drop amount in the cooling period, cutting off a heater according to 60 drops per minute after the heat preservation is ended, vertically cooling a workpiece in oil with the temperature of 50-70 ℃, and lifting the material after the cooling time is generally 10-20 minutes;

and S1.5, tempering the cooled material at low temperature within half an hour, taking the material out of the furnace for air cooling at the temperature of 160-190 ℃ for about 2 hours, and obtaining the alloy steel raw material subjected to surface carburization.

3. The processing method according to claim 1, wherein the step S2 includes the following steps:

S2.1, placing the carburized alloy steel to be treated on a clamping stretching mechanism on heat treatment equipment, sending the carburized alloy steel to a quenching area for quenching, quenching and heating the steel to 1100 ℃ through output current, and then preserving heat until quenching is finished;

S2.2, the clamping straightening mechanism continues to move forward, in the process, the carburized alloy steel is cooled to 30-50 ℃, after the carburized alloy steel reaches a tempering area, a tempering electrode is heated to start working, the tempering temperature reaches 650-670 ℃, heat preservation is carried out for 30-50S, and after the tempering is finished, the carburized alloy steel continues to move forward and is cooled;

S2.3, the clamping stretching mechanism comes to a secondary tempering area, the carburized alloy steel is cooled to 30-50 ℃ and then is subjected to secondary tempering, the tempering temperature reaches 650-670 ℃, heat preservation is carried out for 30-50S, after the secondary tempering, the whole heat treatment process is finished, the carburized alloy steel is naturally cooled, and the carburized alloy steel is fed to a feeding area; the clamping stretching mechanism returns to the original feeding area for the next round of heat treatment production.

4. A carburized straight shank product produced by the process of claim 1.

Technical Field

The invention mainly relates to a brand new production process of a straight ejector rod product, and mainly relates to a processing method capable of improving the surface toughness and hardness of product raw materials, in particular alloy tool steel, and further improving the wear resistance and fatigue resistance of the straight ejector rod product.

background

The traditional mould straight ejector rod on the existing market mainly has two forms: the die straight ejector rod made of the alloy tool steel is made of common alloy tool steel without any treatment on the surface, has larger defects in the aspects of surface hardness, wear resistance, fatigue strength, seizure resistance and the like, is difficult to meet the use requirement of the die, has poor atmosphere and superheated steam corrosion resistance and tempering softening resistance, has higher notch sensitivity, and belongs to a lower-grade product in the die straight ejector rod.

the other is to add a nitriding process on the basis of the product, and carry out nitriding treatment on the surface of a common alloy tool steel raw material, so that the process really solves the problems of poor surface hardness, wear resistance, fatigue strength and seizure resistance, improves the atmospheric and superheated steam corrosion resistance and tempering softening resistance, and reduces the notch sensitivity. However, the core hardness is low, and the infiltration layer is shallow, so that the wear-resistant and fatigue-resistant requirements of bearing light and medium loads can be generally met, and the heat resistance and corrosion resistance of the infiltration layer can not achieve the use effect of the hot working die; the nitriding hardness of the surface is uneven and is not well controlled after nitriding, which indicates that the nitride is not well dissolved and diffused into the product; and the deformation and bending phenomena of steel are easily generated in the nitriding process, so that the product reject ratio is improved.

Therefore, there is a need in the art for a new process to produce a new mold straight ejector pin to solve the problems of uneven nitrided hardness and bending distortion of the product due to the shallow nitrided layer with high hardness.

Disclosure of Invention

In order to make up for the defects of the prior art, the invention provides a production process method of a straight ejector rod with high toughness, high hardness, uniformity and low reject ratio.

The invention adopts the following technical scheme:

S1, firstly, carrying out a surface carburization treatment process on an alloy steel raw material, wherein the alloy tool steel raw material comprises 0.35-0.45% of carbon element, 0.8-1.2% of silicon element, 0.3-0.5% of manganese element, less than or equal to 0.03% of phosphorus element, less than or equal to 0.02% of sulfur element, 5.0-5.5% of chromium element, 1.3-1.6% of molybdenum element, 1.0-1.25% of vanadium element and the balance of iron element;

s2, carrying out heat treatment on the carburized alloy steel;

S3, processing of carburized alloy steel ejector rod

S3.1 nitriding: cleaning the surface of the carburized alloy steel, and charging the washed straight carburized alloy steel within two hours, wherein the height of the alloy steel cannot exceed that of an exhaust pipe; heating up, heating up to 420 +/-10 ℃ after heating up for 1.5h, introducing ammonia gas, controlling the flow of ammonia gas to be 2-3 MPa/h, continuing heating up, introducing 0.5-1h, heating up to 530 +/-10 ℃, increasing the pressure of ammonia gas to 3-4 MPa/h, entering a heat preservation state, preserving heat for 2-2.5h, reducing the pressure of ammonia gas to 1.5 MPa/h, preserving heat for 3-4h, closing the ammonia gas, cooling to below 300 ℃, and discharging;

S3.2, after the straight strip carburized alloy steel is cut into short rods with corresponding specifications, the processes of fine grinding, upsetting, head forming and polishing are sequentially carried out.

Further, the step S1 includes the following specific steps:

s1.1, raising the temperature of a furnace to 800 +/-10 ℃, placing a disc-shaped alloy tool steel raw material to be treated into a carburizing periodic furnace, closing a furnace cover, raising the temperature to 930 +/-10 ℃, dropping kerosene into the furnace at a speed of 160 drops per minute in the process of raising the temperature, and exhausting gas for 60-80 minutes generally;

s1.2, judging a strong permeation time point, increasing the dropping amount of kerosene during strong permeation, putting a test bar during strong permeation according to 180-200 drops per minute, wherein the carburizing speed is 0.15-0.2 mm/h, and when the depth of an upper permeation layer of the test bar reaches one half, the next diffusion period can be carried out after the strong permeation is finished;

s1.3, keeping the temperature unchanged in a diffusion period, reducing the kerosene drop amount, and controlling the diffusion time to be 60-90 minutes according to 100 drops per minute;

s1.4, starting cooling after the diffusion period is ended, cooling to 810 +/-10 ℃, preserving heat for 10-20 minutes at the temperature, reducing the kerosene drop amount in the cooling period, cutting off a heater according to 60 drops per minute after the heat preservation is ended, vertically cooling a workpiece in oil with the temperature of 50-70 ℃, and lifting the material after the cooling time is generally 10-20 minutes;

And S1.5, tempering the cooled material at low temperature within half an hour, taking the material out of the furnace for air cooling at the temperature of 160-190 ℃ for about 2 hours, and obtaining the alloy steel raw material subjected to surface carburization.

further, the step S2 includes the following specific steps:

S2.1, placing the carburized alloy steel to be treated on a clamping stretching mechanism on heat treatment equipment, sending the carburized alloy steel to a quenching area for quenching, quenching and heating the steel to 1100 ℃ through output current, and then preserving heat until quenching is finished;

s2.2, the clamping straightening mechanism continues to move forward, in the process, the carburized alloy steel is cooled to 30-50 ℃, after the carburized alloy steel reaches a tempering area, a tempering electrode is heated to start working, the tempering temperature reaches 650-670 ℃, heat preservation is carried out for 30-50S, and after the tempering is finished, the carburized alloy steel continues to move forward and is cooled;

S2.3, the clamping stretching mechanism comes to a secondary tempering area, the carburized alloy steel is cooled to 30-50 ℃ and then is subjected to secondary tempering, the tempering temperature reaches 650-670 ℃, heat preservation is carried out for 30-50S, after the secondary tempering, the whole heat treatment process is finished, the carburized alloy steel is naturally cooled, and the carburized alloy steel is fed to a feeding area; and the hardness of the finally heat-treated carburized alloy steel core can reach 52HRC, the surface hardness can reach 62HRC, and the clamping stretching mechanism returns to the initial feeding area for the next round of heat treatment production.

Has the advantages that: the method provided by the invention solves the problems of shallow nitriding layer, uneven nitriding hardness and bending distortion of the product although the existing nitriding layer has high hardness. The method is simple and easy to popularize, and effectively reduces the cost.

Detailed Description

The invention is described in more detail below with reference to specific examples, without limiting the scope of the invention. The apparatus used for heat treatment of carburized alloy steel in this example was the quenching and tempering heat treatment apparatus described in CN2017107691589 patent application.