Pin shaft production process

Abstract

The invention discloses a pin shaft production process, which comprises a machining process, heat treatment and surface strengthening treatment, the machining process comprises blanking, forging and turning, the heat treatment comprises normalizing treatment, quenching treatment and tempering treatment, and the surface strengthening treatment comprises acid-alkali bath, water washing, drying, nitriding, sand blasting and oxidation treatment. By means of the pin shaft production process, the corrosion resistance, abrasion resistance and impact resistance of the pin shaft are improved, the stability of the performance of the pin shaft is improved, the service life of the pin shaft is prolonged, the mechanical performance is excellent, and the surface quality is good.

Description

Technical Field

[0001] The invention relates to the technical field of metal parts production technology, in particular to a pin production technology. Background Art

[0002] Pins are a type of standardized fasteners that can be used for static fixed connections or for relative movement with the connected parts. They are mainly used at the hinges of two parts to form hinged connections. Pins are usually locked with cotter pins, which are reliable and easy to disassemble. They are widely used in engineering vehicles, logistics loading and unloading equipment, trains, production equipment, engineering, terminal logistics, machinery, metallurgy, chemical industry, etc., working arms, cylinders, oil cylinders and various pin connection mechanism equipment.

[0003] With the increasing size and complexity of working conditions of construction machinery, the comprehensive performance requirements of the strength, hardness, wear resistance and impact resistance of parts such as pins have been greatly increased. Correspondingly, the requirements for heat treatment and surface treatment of parts have become more stringent. For example, the working pin of the crane boom has a large load-bearing capacity and complex load-bearing conditions, which requires the pin surface to have higher hardness, wear resistance and impact resistance, as well as better corrosion resistance.

[0004] Therefore, the above problems have become technical problems that need to be solved urgently. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a pin production process to improve the corrosion resistance, wear resistance, impact resistance and other properties of the pin, so that the pin product can obtain ideal mechanical properties, tolerance and service life.

[0006] Technical solution: In order to achieve the above-mentioned purpose, the present invention provides a pin production process, including machining process, heat treatment and surface strengthening treatment; The material of the pin is 40Cr steel, the machining process includes blanking, forging, turning, the heat treatment includes normalizing, quenching and tempering, and the surface strengthening treatment includes acid and alkali bath, water washing, drying, nitriding, sandblasting and oxidation treatment; the pin production process is as follows: S1, blanking: using a cutting machine, cut the long steel into sections according to the design requirements to form sections; S2: Forging: Forging the above-mentioned segments at an initial forging temperature of 1200-1245°C and a final forging temperature of 760-970°C to form a blank; S3, normalizing treatment; S4, Turning: First, rough turn the pin's shape, then semi-finish turn the pin's end face, leave allowance on both sides during turning, and then perform fine turning or grinding; S5, acid-base bath: soak the workpiece in alkaline liquid and acidic liquid successively, and then wash with water; S6, drying: placing the workpiece in a drying box for drying to remove moisture from the surface of the workpiece; S7, nitriding: placing the pin in a nitriding furnace for nitriding treatment; S8, quenching treatment: the workpiece is moved to an isothermal tank for precooling and then directly quenched; S9, tempering treatment: tempering temperature 150-250℃, tempering furnace insulation 90-120min; S10, sandblasting: sandblasting or shot blasting the workpiece to remove the loose layer outside the compound layer; S11, oxidation treatment: the workpiece is subjected to oxidation treatment so that the surface of the diffusion layer is covered with an oxide layer.

[0007] Furthermore, the normalizing treatment in step S3 is specifically performed at a normalizing temperature of 970±10° C. and kept at this temperature for 2-3 hours, and then the blank is taken out and air-cooled.

[0008] Furthermore, the specific operation method of step S5 is: first degrease the workpiece using an activator, ultrasonically clean it, then soak it in an alkaline solution for 30-60 minutes, take it out and ultrasonically clean it, then soak it in an acid solution for 5-10 minutes, take it out and ultrasonically clean it, and finally wash it with water at room temperature.

[0009] Furthermore, the specific method of the nitriding treatment in step S7 is to install the pin in a nitriding furnace, preheat the nitriding furnace to 500-550°C, the ammonia decomposition rate is 30%-40% in the first 5-6 hours of the insulation period, and the ammonia decomposition rate is 60%-80% in the last 3-4 hours of the insulation period, then the furnace is cooled to 400°C, and finally air-cooled. The depth of the nitriding layer on the surface of the pin is 0.3-0.4mm, the surface hardness is ≥650HV, and the thickness of the nitriding layer reaches 20-50μm.

[0010] Furthermore, the specific operation of the oxidation treatment in step S11 is to perform oxidation treatment on the workpiece at a temperature of 300 to 400° C. for 10 to 60 minutes, so that the surface of the infiltrated layer is covered with an oxide layer.

[0011] Furthermore, the acid solution is boric acid or oxalic acid, and the alkali solution is any one of ammonium bicarbonate, ammonium sulfate, sodium carbonate or sodium bicarbonate solution.

[0012] Furthermore, steps S7, S10, and S11 are repeated at least once.

[0013] Furthermore, the tempering treatment is performed at least twice.

[0014] It can be seen from the above technical solution that the present invention has the following beneficial effects: Through the pin production process provided by the present invention, the corrosion resistance, wear resistance and impact resistance of the pin are improved, the stability and service life of the pin performance are improved, the mechanical properties are excellent, and the surface quality is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The utility model is a process flow chart of a pin shaft production process. DETAILED DESCRIPTION

[0016] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more specific definition of the protection scope of the present invention. The embodiments of the present invention include the following parts: Embodiment 1: like Figure 1 As shown, a pin production process includes machining process, heat treatment and surface strengthening treatment; In this embodiment, the material of the pin is 40Cr steel, the machining process includes blanking, forging, turning, the heat treatment includes normalizing, quenching and tempering, and the surface strengthening treatment includes acid and alkali bath, water washing, drying, nitriding, sandblasting and oxidation treatment; the pin production process is as follows: S1, blanking: using a cutting machine, cut the long steel into sections according to the design requirements to form sections; S2: Forging: Forging the above-mentioned segments at an initial forging temperature of 1210°C and a final forging temperature of 760°C to form a blank; S3, normalizing treatment; S4, Turning: First, rough turn the pin's shape, then semi-finish turn the pin's end face, leave allowance on both sides during turning, and then perform fine turning or grinding; S5, acid-base bath: soak the workpiece in alkaline liquid and acidic liquid successively, and then wash with water; S6, drying: placing the workpiece in a drying box for drying to remove moisture from the surface of the workpiece; S7, nitriding: placing the pin in a nitriding furnace for nitriding treatment; S8, quenching treatment: the workpiece is moved to an isothermal tank for precooling and then directly quenched; S9, tempering treatment: tempering temperature 175℃, tempering furnace insulation 90min; S10, sandblasting: sandblasting or shot blasting the workpiece to remove the loose layer outside the compound layer; S11, oxidation treatment: the workpiece is subjected to oxidation treatment so that the surface of the diffusion layer is covered with an oxide layer.

[0017] The normalizing treatment in step S3 is specifically performed at a normalizing temperature of 970° C. and kept at that temperature for 2.5 hours, and then the blank is taken out and air-cooled.

[0018] The specific operation method of step S5 is: first degrease the workpiece using an activator, perform ultrasonic cleaning, then soak it in an alkaline solution for 30 minutes, take it out and perform ultrasonic cleaning, then soak it in an acid solution for 5 minutes, take it out and perform ultrasonic cleaning, and finally wash it with water at room temperature.

[0019] The specific method of the nitriding treatment in step S7 is to install the pin in a nitriding furnace, preheat the nitriding furnace to 500°C, set the ammonia decomposition rate to 35% in the first 5-6 hours of the insulation period, set the ammonia decomposition rate to 60% in the last 3-4 hours of the insulation period, then cool the furnace to 400°C, and finally air cool. The depth of the nitriding layer on the surface of the pin is 0.3mm, the surface hardness is ≥650HV, and the thickness of the nitriding layer reaches 20μm.

[0020] The specific operation of the oxidation treatment in step S11 is to perform oxidation treatment on the workpiece at a temperature of 370° C. for 25 minutes, so that the surface of the infiltrated layer is covered with an oxide layer.

[0021] The acid solution is boric acid or oxalic acid, and the alkali solution is any one of ammonium bicarbonate, ammonium sulfate, sodium carbonate or sodium bicarbonate solution.

[0022] The steps S7, S10 and S11 are repeated once.

[0023] The tempering treatment is performed twice.

[0024] Embodiment 2: A pin production process, including machining process, heat treatment and surface strengthening treatment; The material of the pin is 45# steel, the machining process includes blanking, forging, turning, the heat treatment includes normalizing, quenching and tempering, and the surface strengthening treatment includes acid and alkali bath, water washing, drying, nitriding, sandblasting and oxidation treatment; the pin production process is as follows: S1, blanking: using a cutting machine, cut the long steel into sections according to the design requirements to form sections; S2: Forging: Forging the above-mentioned segments at an initial forging temperature of 1230°C and a final forging temperature of 890°C to form a blank; S3, normalizing treatment; S4, Turning: Firstly, rough turn the pin's shape, then semi-finish turn the pin's end face, leave allowance on both sides during turning, and then do fine turning or grinding; S5, acid-base bath: soak the workpiece in alkaline liquid and acidic liquid successively, and then wash with water; S6, drying: placing the workpiece in a drying box for drying to remove moisture from the surface of the workpiece; S7, nitriding: placing the pin in a nitriding furnace for nitriding treatment; S8, quenching treatment: the workpiece is moved to an isothermal tank for precooling and then directly quenched; S9, tempering treatment: tempering temperature 200℃, tempering furnace insulation 100min; S10, sandblasting: sandblasting or shot blasting the workpiece to remove the loose layer outside the compound layer; S11, oxidation treatment: the workpiece is subjected to oxidation treatment so that the surface of the diffusion layer is covered with an oxide layer.

[0025] The normalizing treatment in step S3 is specifically performed at a normalizing temperature of 980° C. and kept at that temperature for 3 hours, and then the blank is taken out and air-cooled.

[0026] The specific operation method of step S5 is: first use an activator to degrease the workpiece, ultrasonically clean it, then soak it in alkaline solution for 50 minutes, take it out and ultrasonically clean it, then soak it in acid solution for 10 minutes, take it out and ultrasonically clean it, and finally wash it with water at room temperature.

[0027] The specific method of the nitriding treatment in step S7 is to install the pin in a nitriding furnace, preheat the nitriding furnace to 530°C, set the ammonia decomposition rate to 40% in the first 5-6 hours of the insulation period, and set the ammonia decomposition rate to 65% in the last 3-4 hours of the insulation period, then cool the furnace to 400°C, and finally air cool. The nitriding layer on the surface of the pin has a depth of 0.35mm, a surface hardness of ≥650HV, and a thickness of the nitriding layer reaches 35μm.

[0028] The specific operation of the oxidation treatment in step S11 is to perform oxidation treatment on the workpiece at a temperature of 390° C. for 35 minutes, so that the surface of the infiltrated layer is covered with an oxide layer.

[0029] The acid solution is boric acid or oxalic acid, and the alkali solution is any one of ammonium bicarbonate, ammonium sulfate, sodium carbonate or sodium bicarbonate solution.

[0030] The steps S7, S10 and S11 are repeated twice.

[0031] The tempering treatment is performed twice.

[0032] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A pin production process, characterized in that: Including machining process, heat treatment and surface strengthening treatment; The material of the pin is 40Cr steel, the machining process includes blanking, forging, turning, the heat treatment includes normalizing, quenching and tempering, and the surface strengthening treatment includes acid and alkali bath, water washing, drying, nitriding, sandblasting and oxidation treatment; the pin production process is as follows: S1, blanking: using a cutting machine, cut the long steel into sections according to the design requirements to form sections; S2: Forging: Forging the above-mentioned segments at an initial forging temperature of 1200-1245°C and a final forging temperature of 760-970°C to form a blank; S3, normalizing treatment; S4, Turning: First, rough turn the pin's shape, then semi-finish turn the pin's end face, leave allowance on both sides during turning, and then perform fine turning or grinding; S5, acid-base bath: soak the workpiece in alkaline liquid and acidic liquid successively, and then wash with water; S6, drying: placing the workpiece in a drying box for drying to remove moisture from the surface of the workpiece; S7, nitriding: placing the pin in a nitriding furnace for nitriding treatment; S8, quenching treatment: the workpiece is moved to an isothermal tank for precooling and then directly quenched; S9, tempering treatment: tempering temperature 150-250℃, tempering furnace insulation 90-120min; S10, sandblasting: sandblasting or shot blasting the workpiece to remove the loose layer outside the compound layer; S11, oxidation treatment: the workpiece is subjected to oxidation treatment so that the surface of the diffusion layer is covered with an oxide layer.

2. A pin production process according to claim 1, characterized in that: The normalizing treatment in step S3 is specifically performed at a normalizing temperature of 970±10° C. and kept at that temperature for 2-3 hours, and then the blank is taken out and air-cooled.

3. A pin production process according to claim 1, characterized in that: The specific operation method of step S5 is: first degrease the workpiece using an activator, perform ultrasonic cleaning, then soak it in an alkaline solution for 30-60 minutes, take it out and perform ultrasonic cleaning, then soak it in an acid solution for 5-10 minutes, take it out and perform ultrasonic cleaning, and finally wash it with water at room temperature.

4. A pin production process according to claim 1, characterized in that: The specific method of the nitriding treatment in step S7 is to install the pin in a nitriding furnace, preheat the nitriding furnace to 500-550°C, decompose the ammonia to 30%-40% in the first 5-6 hours of the insulation period, and decompose the ammonia to 60%-80% in the last 3-4 hours of the insulation period, then cool the furnace to 400°C, and finally air cool, the depth of the nitriding layer on the surface of the pin is 0.3-0.4mm, the surface hardness is ≥650HV, and the thickness of the nitriding layer reaches 20-50μm.

5. A pin production process according to claim 1, characterized in that: The specific operation of the oxidation treatment in step S11 is to perform oxidation treatment on the workpiece at a temperature of 300-400° C. for 10-60 min, so that the surface of the infiltrated layer is covered with an oxide layer.

6. A pin production process according to claim 1, characterized in that: The acid solution is boric acid or oxalic acid, and the alkali solution is any one of ammonium bicarbonate, ammonium sulfate, sodium carbonate or sodium bicarbonate solution.

7. A pin production process according to claim 1, characterized in that: The steps S7, S10 and S11 are repeated at least once.

8. A pin production process according to claim 1, characterized in that: The tempering treatment is performed at least twice.

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