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A kind of cold-drawn steel pipe mandrel and preparation method thereof

A technology of cold-drawn steel pipes and mandrels, which is applied in the direction of manufacturing tools, heat treatment equipment, furnaces, etc., can solve problems such as short service life, plastic deformation, and temperature rise of mandrels, and achieve a long service life, compact structure, and high hardness. Effect

Active Publication Date: 2016-06-29
重庆赛飞斯金属材料股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Cold drawing dies usually include a mold sleeve and a mold core. The mold core is placed in the mold sleeve. When working, the outer surface and the inner wall of the steel pipe will produce strong friction (the stress on the sizing belt will be as high as nearly 3000Mpa), while the ordinary core mold is due to its strength and hardness. , The toughness is not up to standard, not only the service life is short, but also the inner diameter of the steel pipe cannot be controlled, and the quality of the inner wall of the pipe cannot be guaranteed; in addition, during the drawing process, the inner wall of the steel pipe will undergo strong plastic deformation, which will increase the temperature of the core mold to 300 ° C. This requires the mandrel material to have a certain tempering stability
For this reason, some manufacturers adopt heat treatment methods such as quenching and tempering + surface chrome plating to improve the wear resistance of the mandrel, but the hardness and wear resistance of this method are not high enough to meet the requirements of the product, especially for the production of high-strength steel pipes. The contradiction is particularly prominent when

Method used

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  • A kind of cold-drawn steel pipe mandrel and preparation method thereof
  • A kind of cold-drawn steel pipe mandrel and preparation method thereof
  • A kind of cold-drawn steel pipe mandrel and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] The method for preparing the cold-drawn steel pipe mandrel in this embodiment comprises the following steps:

[0031] 1) Sampling: select Cr 12 Mo 1 V 1 Raw materials and preliminary processing to obtain semi-finished core molds;

[0032] 2) Heat treatment: first high-temperature quenching (quenching temperature is 1020°C, quenching medium is liquid nitrogen) to process the mandrel obtained in step 1), and then high-temperature tempering treatment (tempering temperature is 520°C, medium is air);

[0033] 3) Machining: Finishing processing step 2) obtained mandrel;

[0034] 4) TD processing, including:

[0035] i, cleaning: cleaning removal step 3) oil stain and rust on the surface of the gained mandrel;

[0036] ii. Preheating: place the mandrel obtained in i at 500°C for 45 minutes;

[0037] iii. Salt bath treatment: add the mandrel of ii to a 950°C salt bath for 10 hours;

[0038] iv. Austempering: put the mandrel of iii into a 750°C salt bath for isothermal qu...

Embodiment 2

[0044] The method for preparing the cold-drawn steel pipe mandrel in this embodiment comprises the following steps:

[0045] 1) Sampling: select Cr 12 Mo 1 V 1 Raw materials and preliminary processing to obtain semi-finished core molds;

[0046] 2) Heat treatment: first high-temperature quenching (quenching temperature is 1080°C, medium is liquid nitrogen) to process the core mold obtained in step 1), and then high-temperature tempering treatment (tempering temperature is 540°C, medium is air);

[0047] 3) Machining: Finishing processing step 2) obtained mandrel;

[0048] 4) TD processing, including:

[0049] i, cleaning: cleaning removal step 3) oil stain and rust on the surface of the gained mandrel;

[0050] ii. Preheating: place the mandrel obtained in i at 600°C for 30 minutes;

[0051] iii. Salt bath treatment: Add the mandrel of ii to a 1000°C salt bath for 5 hours;

[0052] iv. Austempering: put the mandrel of iii into a 720°C salt bath for isothermal quenching,...

Embodiment 3

[0057] The method for preparing the cold-drawn steel pipe mandrel in this embodiment comprises the following steps:

[0058] 1) Sampling: select Cr 12 Mo 1 V 1 Raw materials and preliminary processing to obtain semi-finished core molds;

[0059] 2) Heat treatment: first high-temperature quenching (quenching temperature is 1050°C, quenching medium is liquid nitrogen) to process the mandrel obtained in step 1), and then high-temperature tempering treatment (tempering temperature is 520°C, medium is air);

[0060] 3) Machining: Finishing processing step 2) obtained mandrel;

[0061] 4) TD processing, including:

[0062] i, cleaning: cleaning removal step 3) oil stain and rust on the surface of the gained mandrel;

[0063] ii. Preheating: place the mandrel obtained in i at 400°C for 60 minutes;

[0064] iii. Salt bath treatment: add the mandrel of ii to a 900°C salt bath for 15 hours;

[0065] iv. Austempering: put the mandrel of iii into a 700°C salt bath for isothermal qu...

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Abstract

The invention discloses a cold-drawn steel pipe mandrel. The cold-drawn steel pipe mandrel is 10-70mm in diameter and 50-80mm in length, a ceramic film which is 5-15 microns in thickness is compounded on the surface of the cold-drawn steel pipe mandrel. The invention also discloses a preparation method of the cold-drawn steel pipe mandrel. The method comprises the following steps: 1) selecting a to-be-processed mandrel; 2) quenching at a high temperature, and tempering the mandrel in the step 1) at the high temperature; and 3) carrying out TDS treatment, firstly, cleaning the mandrel obtained in the step 2), processing the mandrel at 400-600 DEG C for 30-60 minutes, processing in a salt bath at 900-1100 DEG C for 5-15 hours, adding the mandrel to a salt bath at 600-800 DEG C, carrying out isothermal quenching, carrying out air cooling to a room temperature, and finally, tempering and polishing at 480-540 DEG C, so as to obtain the finished product. The cold-drawn steel pipe mandrel prepared by the method is compact in structure, and has good strain resistance and metal occlusion resistance; the surface hardness HV is greater than 2800; and the service life of the mandrel can be prolonged by 5-15 times.

Description

technical field [0001] The invention belongs to the field of metal drawing and forming, and relates to a die for steel pipe cold drawing, in particular to a cold drawn steel pipe mandrel and a preparation method thereof. Background technique [0002] Cold drawing is a common metal processing technology, which is widely used in the production of seamless steel pipes. Cold drawing of steel pipes has great influence on the strength, toughness, wear resistance, corrosion resistance, friction coefficient and fatigue performance of cold drawing dies. high demands. Cold drawing dies usually include a mold sleeve and a mold core. The mold core is placed in the mold sleeve. When working, the outer surface and the inner wall of the steel pipe will produce strong friction (the stress on the sizing belt will be as high as nearly 3000Mpa), while the ordinary core mold is due to its strength and hardness. , The toughness is not up to standard, not only the service life is short, but also...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/00C21D1/18C21D1/20
Inventor 张军周卫宁
Owner 重庆赛飞斯金属材料股份有限公司