阅读说明：本技术 一种碳钢线材空淬方法及装置 (Carbon steel wire air quenching method and device ) 是由 白新歌 迟旭 刘勇 于 2021-08-31 设计创作，主要内容包括：本发明提供一种碳钢线材空淬方法,包括以下步骤：S1：线材通过炉管输送至淬火炉内,经淬火炉加热至Ac3转变点以上20-30℃,保温0.26-3.0min；S2：上述步骤S1得到的线材经炉管输送至水冷槽一内冷却,水冷槽一的长度为3-5m,其内部冷却水温度为7-14℃；S3：上述步骤S2得到的线材经炉管输送至水冷槽二内冷却,水冷槽二的长度为4-8m,其内部冷却水温度为20-30℃；一种碳钢线材空淬装置,包括淬火炉,还包括水冷槽一,水冷槽一设置在淬火炉输出端。本发明将原先的油淬改为气淬,线材沿炉管输送,不与淬火介质接触,使线材表面不被氧化；由于淬火时没有油类淬火介质,不仅可以保持炉管内的清洁度,且能保证在回火后线材表面也是均匀光亮的,可满足对线材表面质量的要求。(The invention provides a carbon steel wire air quenching method, which comprises the following steps: s1: conveying the wire rod into a quenching furnace through a furnace tube, heating the wire rod to be 20-30 ℃ above the Ac3 transformation point through the quenching furnace, and preserving heat for 0.26-3.0 min; s2: conveying the wire obtained in the step S1 to a first water cooling tank through a furnace tube for internal cooling, wherein the length of the first water cooling tank is 3-5m, and the temperature of internal cooling water is 7-14 ℃; s3: the wire obtained in the step S2 is conveyed to a second water cooling tank through a furnace tube to be cooled, the length of the second water cooling tank is 4-8m, and the temperature of the cooling water in the second water cooling tank is 20-30 ℃; the air quenching device for the carbon steel wire comprises a quenching furnace and a first water cooling tank, wherein the first water cooling tank is arranged at the output end of the quenching furnace. The original oil quenching is changed into gas quenching, and the wire rod is conveyed along the furnace tube and is not contacted with a quenching medium, so that the surface of the wire rod is not oxidized; because no oil quenching medium is used during quenching, the cleanliness of the furnace tube can be maintained, the surface of the wire rod after tempering is ensured to be even and bright, and the requirement on the surface quality of the wire rod can be met.)

1. The air quenching method of the carbon steel wire is characterized by comprising the following steps of:

s1: conveying the wire rod into a quenching furnace through a furnace tube, heating the wire rod to be 20-30 ℃ above the Ac3 transformation point through the quenching furnace, and preserving heat for 0.26-3.0 min;

s2: conveying the wire obtained in the step S1 to a first water cooling tank through a furnace tube for internal cooling, wherein the length of the first water cooling tank is 3-5m, and the temperature of internal cooling water is 7-14 ℃;

s3: the wire obtained in the step S2 is conveyed to a second water cooling tank through a furnace tube to be cooled, the length of the second water cooling tank is 4-8m, and the temperature of the cooling water in the second water cooling tank is 20-30 ℃;

s4: the wire obtained in the step S3 is conveyed into a tempering furnace through a furnace tube, is heated to the tempering troostite transformation temperature through the tempering furnace, the temperature is 380-500 ℃, is kept for 1.25-25.5min, and is then cooled to the room temperature;

in the steps S2 and S3, a step of introducing a protective gas into the furnace tube to protect the wire rod in the tube is further included.

2. A carbon steel wire air-quenching method as claimed in claim 1, wherein a refrigerator for controlling the temperature of cooling water is externally connected to both the first water-cooling tank and the second water-cooling tank.

3. A carbon steel wire air-quenching method as claimed in claim 1, wherein the shielding gas is a mixed gas obtained by decomposing ammonia, and N is contained in the mixed gas₂：H₂Is 1: 3.

4. A carbon steel wire air-quenching method as claimed in claim 3, wherein the mixed gas is supplied at a rate of 0.10 to 0.20m³The flow of the flow is led into the furnace tube along the direction opposite to the wire rod conveying direction, and the combustible gas is burnt by an ignition tube arranged on the side wall of the furnace tube at the inlet end of the quenching furnace.

5. The utility model provides a carbon steel wire air quenching device, includes quenching furnace (10), its characterized in that still includes:

the first water cooling tank (20) is arranged at the output end of the quenching furnace;

the water cooling tank II (30) is arranged at the output end of the water cooling tank I; and

the tempering furnace (40) is arranged at the output end of the second water cooling tank;

wherein, the wire rod conveying device also comprises a furnace tube (50) which is distributed in sequence through the quenching furnace, the water cooling groove I, the water cooling groove II and the tempering furnace and is used for conveying the wire rods.

6. The air quenching device for the carbon steel wire rod as claimed in claim 5, wherein the first water cooling tank (20) and the second water cooling tank (30) are externally connected with a refrigerator (60) for controlling the temperature of cooling water inside the first water cooling tank and the second water cooling tank.

7. The carbon steel wire air quenching device as claimed in claim 6, wherein the outer wall of the furnace tube at the inlet end of the quenching furnace (10) is further provided with an ignition tube for gas combustion.

8. The air quenching device for carbon steel wires as claimed in any one of claims 5 to 7, wherein the furnace tube (50) extends through the quenching furnace (10), the first water cooling tank (20), the second water cooling tank (30) and the opposite side walls of the tempering furnace (40) in sequence and is extended outwards.

Technical Field

The invention relates to the technical field of wire production, in particular to a method and a device for air quenching of a precision carbon steel wire.

Background

The wire rod is generally made of carbon steel, in the production industry of precise wire rods, particularly small-sized wire rods with the thickness of less than 4.0mm, the carbon steel wire rods often need to be quenched and tempered to achieve the required tensile strength or hardness, in addition, the surface of the wire rod is bright and uniform in color, and the wire rod is one of basic conditions which require the appearance quality of the wire rod to be ensured in the industry.

In the prior art, when a carbon steel wire is quenched, after a workpiece is heated to a temperature above a critical temperature and is kept warm for a period of time, oil is generally used as a quenching medium to cool the workpiece, because the oil is used as the quenching medium, the cooling speed of the wire can be increased, but the following defects exist during oil quenching: (1) oil smoke is generated, and although smoke exhaust equipment is arranged, the oil smoke is difficult to exhaust cleanly, so that a workshop is polluted, and the health of staff is harmed; (2) during oil quenching, a layer of oil covers the surface of the wire rod, and can not be completely removed no matter cleaning or air blowing is carried out, and the residual oil is brought into a tempering furnace and sintered on the surface of the wire rod, so that the color of the surface of the wire rod is uneven; (3) after each oil quenching, the wire rod can take away some oil, so that the waste of resources can be caused after a long time; (4) the high-temperature wire rod is contacted with quenching oil, so that the risk of fire is generated.

Disclosure of Invention

The invention provides a method and a device for air quenching of a carbon steel wire, which do not contain oil quenching media, have uniform bright wire surface and meet the requirements on the wire surface quality.

In order to solve the technical problems, the invention adopts the following technical scheme:

a carbon steel wire air quenching method comprises the following steps:

s1: conveying the wire rod into a quenching furnace through a furnace tube, heating the wire rod to be 20-30 ℃ above the Ac3 transformation point through the quenching furnace, and preserving heat for 0.26-3.0 min;

s2: conveying the wire obtained in the step S1 to a first water cooling tank through a furnace tube for internal cooling, wherein the length of the first water cooling tank is 3-5m, and the temperature of internal cooling water is 7-14 ℃;

s3: the wire obtained in the step S2 is conveyed to a second water cooling tank through a furnace tube to be cooled, the length of the second water cooling tank is 4-8m, and the temperature of the cooling water in the second water cooling tank is 20-30 ℃;

s4: the wire obtained in the step S3 is conveyed into a tempering furnace through a furnace tube, is heated to the tempering troostite transformation temperature through the tempering furnace, the temperature is 380-500 ℃, is kept for 1.25-25.5min, and is then cooled to the room temperature;

in the steps S2 and S3, a step of introducing a protective gas into the furnace tube to protect the wire rod in the tube is further included.

Preferably, the first water cooling tank and the second water cooling tank are externally connected with a refrigerator for controlling the temperature of cooling water.

Preferably, the shielding gas is a mixed gas obtained by decomposing ammonia, and N in the mixed gas₂：H₂Is 1: 3.

The utility model provides a carbon steel wire air quenching device, includes the quenching furnace, still includes:

the first water cooling tank is arranged at the output end of the quenching furnace;

the water cooling tank II is arranged at the output end of the water cooling tank I; and

the tempering furnace is arranged at the output end of the water cooling tank II;

the wire rod conveying device further comprises a furnace tube which penetrates through the quenching furnace, the water cooling groove I, the water cooling groove II and the tempering furnace in sequence and is used for conveying wire rods.

According to the technical scheme, the invention has the following beneficial effects: the original oil quenching is changed into gas quenching (ammonia decomposition protective gas), the wire rod passes through a furnace tube and is not contacted with a quenching medium, and the ammonia decomposition gas contains hydrogen, has a reduction effect, so that the surface of the wire rod is not oxidized, and meets the requirement of bright quenching; because no oil quenching medium exists on the surface of the wire rod during quenching, the wire rod can keep the cleanliness in the furnace pipe after subsequently entering the tempering furnace, and the surface of the wire rod after tempering is ensured to be even and bright, so that the requirement on the surface quality of the wire rod can be met.

Drawings

FIG. 1 is a flow chart of air quenching of a carbon steel wire according to the present invention;

FIG. 2 is a schematic structural view of the air quenching device for carbon steel wires of the present invention;

FIG. 3 is a graph comparing the oil quenching hardness and the gas quenching hardness of carbon steel wires with various dimensions and thicknesses of less than 4.0 mm;

FIG. 4 is a graph comparing the oil-quenched and gas-quenched tensile strengths of carbon steel wires of various sizes less than 4.0mm in thickness;

FIG. 5 is a graph comparing the oil-quenched and gas-quenched yield ratios of carbon steel wires with thickness less than 4.0mm in various sizes;

FIG. 6 is a graph comparing the elongation of oil quenching and gas quenching of carbon steel wires of various sizes less than 4.0mm in thickness;

FIG. 7 is a graph comparing the oil quenching toughness and the gas quenching toughness of carbon steel wires with thickness less than 4.0mm in various sizes.

In the figure: 10. a quenching furnace; 20. a first water cooling tank; 30. a water cooling tank II; 40. tempering furnace; 50. a furnace tube; 60. a refrigerator.

Detailed Description

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to fig. 1, the air quenching method of the carbon steel wire comprises the following steps:

s1: conveying the wire rod into a quenching furnace through a furnace tube, heating the wire rod to be 20-30 ℃ above the Ac3 transformation point through the quenching furnace, and preserving heat for 0.26-3.0 min;

s2: conveying the wire obtained in the step S1 to a first water cooling tank through a furnace tube for internal cooling, wherein the length of the first water cooling tank is 3-5m, and the temperature of internal cooling water is 7-14 ℃;

s3: the wire obtained in the step S2 is conveyed to a second water cooling tank through a furnace tube to be cooled, the length of the second water cooling tank is 4-8m, and the temperature of the cooling water in the second water cooling tank is 20-30 ℃;

s4: the wire obtained in the step S3 is conveyed into a tempering furnace through a furnace tube, is heated to the tempering troostite transformation temperature through the tempering furnace, the temperature is 380-500 ℃, is kept for 1.25-25.5min, and is then cooled to the room temperature;

wherein Ac3 is the austenitizing temperature line of the hypoeutectoid steel in the equilibrium state, and the steps S2 and S3 further include the step of introducing a protective gas into the furnace tube for protecting the wire rod in the tube.

In order to control the temperature of cooling water in the first water-cooling tank and the second water-cooling tank, the first water-cooling tank and the second water-cooling tank are both externally connected with a refrigerating machine.

As a preferable technical scheme of the invention, the protective gas is mixed gas after ammonia decomposition, and the mixed gas is N with the volume ratio of 1:3₂And H₂。

Further, the above mixed gas is in the range of 0.10-0.20m³The flow rate of the combustible gas is communicated into the furnace tube along the direction opposite to the conveying direction of the wire rods, the wire rods in the furnace tube are protected, and in addition, in order to prevent the combustible gas from causing harm, an ignition tube is arranged on the side wall of the furnace tube at the inlet end of the quenching furnace, so that the combustible gas is burnt.

Referring to fig. 2, the invention also provides a carbon steel wire air quenching device, which comprises a quenching furnace 10, a first water cooling tank 20, a second water cooling tank 30 and a tempering furnace 40, wherein the first water cooling tank is arranged at the output end of the quenching furnace, the second water cooling tank is arranged at the output end of the first water cooling tank, and the tempering furnace is arranged at the output end of the second water cooling tank, wherein the air quenching device further comprises a furnace tube 50 which sequentially penetrates through the quenching furnace, the first water cooling tank, the second water cooling tank and the side wall of the tempering furnace and extends outwards, and the furnace tube is used for conveying the wire.

Further, the first water cooling tank 20 and the second water cooling tank 30 are externally connected with a refrigerator 60.

Further, an ignition tube for combusting combustible gas is further arranged on the outer wall of the furnace tube at the inlet end of the quenching furnace 10.

Experimental example: the test was carried out using a low alloy medium carbon steel wire of type 55CrSi, with a thickness and width of 3.19 mm 3.88mm, and the air-quench procedure was as follows:

s1: conveying the wire rod into a quenching furnace through a furnace tube, heating the wire rod to be 25 ℃ above the Ac3 transformation point through the quenching furnace, and preserving heat for 1.6 min;

s2: conveying the wire rod obtained in the step S1 to a first water cooling tank through a furnace tube for internal cooling, wherein the length of the first water cooling tank is 4m, and the temperature of the internal cooling water is 10 ℃;

s3: then, the wire rod obtained in the step S2 is conveyed to a second water cooling tank through a furnace tube to be cooled, the length of the second water cooling tank is 6m, and the temperature of the cooling water in the second water cooling tank is 25 ℃;

s4: then the wire obtained in the step S3 is conveyed into a tempering furnace through a furnace tube, is heated to the tempering troostite transition temperature through the tempering furnace, specifically to 440 ℃, is kept for 7.08min, and is cooled to the room temperature;

wherein, in the above steps S2 and S3, the method further comprises introducing a shielding gas into the furnace tube along the opposite direction of the wire rod conveying direction for protecting the wire rod in the tube, wherein the shielding gas is a mixed gas obtained by decomposing ammonia, and the mixed gas is N with the volume ratio of 1:3₂And H₂Is composed of a furnace tube and the speed of the furnace tube is 0.1m³/h。

The mechanical properties of the wire rod obtained by the above air-quenching method and apparatus were measured, including hardness (HV0.5), tensile strength (MPa), yield ratio (%), elongation (%), and toughness (number of bends), and the specific parameters are shown in table 1.

Comparative example:

as a comparative example, an oil quenching experiment was performed using the same kind and specification of materials as those of the experimental example of example 1, and the oil quenching step included the following steps:

s1: conveying the wire rod into a quenching furnace, heating the wire rod to be 25 ℃ above the Ac3 transformation point through the quenching furnace, and keeping the temperature for 1.6 min;

s2: conveying the wire rod obtained in the step S1 to an oil tank for cooling, wherein the temperature of the oil tank is 80 ℃;

s3: and conveying the wire rod obtained in the step S2 into a tempering furnace, heating the wire rod to the tempering troostite transition temperature through the tempering furnace, specifically, keeping the temperature at 440 ℃, keeping the temperature for 7.08min, and then cooling the wire rod to the room temperature.

The mechanical properties of the wire rods obtained by the oil quenching method were also measured, and the specific parameters including hardness (HV0.5), tensile strength (MPa), yield ratio (%), elongation (%), and toughness (number of bending) are summarized in table 1.

Note: the hardness is measured by a Vickers hardness tester; the tensile strength, the yield ratio, the elongation and the toughness are measured by an electronic universal testing machine, and the testing machine is suitable for various mechanical property testing tests of various metal materials and non-metal materials.

TABLE 13.19 comparison table of mechanical properties of oil quenching and gas quenching for 3.88mm carbon steel wire

In order to verify that the gas quenching scheme of the invention is applicable to wires with the thickness of less than 4.0mm, the wire with the thickness and the width of 0.40 × 1.76mm, 1.04 × 2.60mm, 1.24 × 2.70mm and 2.63 × 3.42mm is selected, and the gas quenching and oil quenching experiments are sequentially repeated to obtain tables shown in tables 2-5, and in order to visually show the comparison among the carbon steel wire with the specifications in the aspects of hardness, tensile strength, yield ratio, elongation and toughness after the oil quenching and the gas quenching, fig. 3, 4, 5, 6 and 7 are made, wherein UCL in the figures is an upper limit value required to be met by each parameter, and LCL is a lower limit required to be met by each parameter.

TABLE 20.40X 1.76mm carbon steel wire rod oil quenching and gas quenching mechanical property comparison table

TABLE 31.04X 2.60mm carbon steel wire rod oil quenching and gas quenching mechanical property comparison table

TABLE 41.24 comparison table of oil-quenched and gas-quenched mechanical properties of 2.70mm carbon steel wire

TABLE 52.63 comparison table of oil-quenched and gas-quenched mechanical properties of 3.42mm carbon steel wire

As can be seen from the above table, in the gas quenching in example 1, compared with the conventional oil quenching, the gas quenching can completely replace the oil quenching in terms of hardness, tensile strength, yield ratio, elongation and toughness, and the wire rod after the gas quenching has the hardness, tensile strength, yield ratio, elongation and toughness meeting the relevant requirements. The reason for this is that: the carbon steel wire is subjected to austenitizing transformation in a quenching furnace and then enters a low-temperature water-cooling tank I for rapid cooling, so that super-cooled austenite is rapidly cooled to be close to the martensite transformation point, and the precipitation of proeutectoid ferrite is avoided; and then the wire rod enters a water cooling tank II to be quenched so as to obtain a martensite structure, and finally the wire rod enters a tempering furnace to be tempered, so that the hardness and the mechanical property of the wire rod meet certain requirements.

The method changes the original oil quenching into gas quenching (ammonia decomposition protective gas), leads the wire rod to pass through a furnace tube without contacting with a quenching medium, and leads the ammonia decomposition gas to contain hydrogen, thereby having the reduction function, leading the surface of the wire rod not to be oxidized and meeting the requirements of bright quenching; because no oil quenching medium exists on the surface of the wire rod during quenching, the wire rod can keep the cleanliness in the furnace pipe after subsequently entering the tempering furnace, and the surface of the wire rod after tempering is ensured to be even and bright, so that the requirement on the surface quality of the wire rod can be met.

Therefore, the wire rod subjected to gas quenching can avoid medium oil from adhering to the surface of the wire rod, the surface color of the wire rod can be ensured to be uniform, the problems of waste of quenching oil and environmental pollution can not be caused, and the risk of ignition of the quenching oil can be further reduced.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.