CN115679048A - Stainless steel wire drawing machine graded heating annealing oxygen-blocking system - Google Patents

Abstract

A graded heating annealing oxygen barrier system for a stainless steel wire drawing machine disclosed in the present invention has multiple stainless steel wires running in parallel; each stainless steel wire passes through its own oven pipe section, exposed section, wire feeding pipe section, annealing heating pipe section, Cooling pipe section and wire outlet pipe section. The stainless steel wire annealing furnace section is heated to the annealing temperature in a reducing atmosphere, and then goes out of the wire outlet pipe after being cooled by the cooling pool. The reducing gas enters from the junction of the annealing furnace tube section and the cooling tube section, flows in the reverse direction towards the wire feeding tube section, and is discharged after burning and consuming oxygen in the exposed section. The stainless steel wire annealing equipment of the present invention has a simple and ingenious structure, the reducing gas has multiple functions of blocking oxygen, preheating, and reducing air pollution, and the appearance quality of the stainless steel wire after annealing is high.

Description

Graded heating annealing oxygen barrier system for stainless steel wire drawing machine

technical field

The invention relates to an annealing technology in the steel wire drawing process.

Background technique

The heat treatment of stainless steel is generally a solution heat treatment in an annealing furnace, which is usually called "annealing", and the temperature range is 1040~1120 °C. The annealing atmosphere generally uses pure hydrogen as the annealing atmosphere, and the purity of the atmosphere is preferably above 99.99%. If the other part of the atmosphere is an inert gas, the purity can be lower, but it must not contain too much oxygen or water vapor.

The invention of 2014107925319 provides an annealing process for raw wire for stainless steel welding wire. Before wire drawing, the coil of the raw wire is annealed in an annealing furnace, so that the furnace temperature gradually rises to the temperature required by the process and then cools down. This technology can be used as the reference content of the technology of the present invention.

2021.9 "Chemical Management" published "Several Processes for Cold-rolled Stainless Steel Annealing and Pickling Lines". The article introduced that hydrogen is mainly used as a protective gas in the industry at present. Since hydrogen is a strong reducing During processing, the purer and higher the concentration of the protective gas in the furnace, the cleaner and brighter the surface of the strip after annealing. However, due to the explosive nature of hydrogen, ammonia decomposition gas is generally used in the industry at present, resulting in a large variable factor in the purity of the protective gas, which requires more airtight control in the design and use of equipment , to ensure that the concentration of the protective gas meets the requirements and achieve the purpose of recrystallization bright annealing. However, the equipment used for the ammonia decomposition gas is limited to the annealing furnace, and the cost is high and the cycle is long.

Contents of the invention

Purpose of the invention:

Provide a stainless steel wire drawing machine graded heating annealing oxygen barrier system with multi-stage heating, oxygen barrier, environmental protection, internal quality and appearance quality can be improved.

Technical solutions:

The graded heating annealing oxygen barrier system of the stainless steel wire drawing machine of the present invention has multiple stainless steel wires arranged in parallel. Pipe section, wire outlet pipe section.

The wire inlet pipe section, the annealing furnace pipe section, the cooling pipe section and the wire outlet pipe section are interconnected and continuous pipelines.

In addition, a reducing gas pipeline is connected between the cooling pipe section and the annealing furnace pipe section (the flow or pressure of the reducing gas pipeline is controlled by a flow valve to ensure that the pressure is greater than atmospheric pressure, which is convenient for reverse flow).

A reducing gas pipeline with a pressure higher than atmospheric pressure is connected between the cooling pipe section and the annealing furnace pipe section. The reducing gas flows in the opposite direction to the running direction of the stainless steel wire, so that the stainless steel wire is simultaneously hydrogenated during heat treatment at the annealing temperature. The gas then exits through the opening at the junction of the feed tube section and the bare section.

The outlet of the outlet pipe section is the bundle opening (basically airtight, the diameter of the tail end of the wire inlet pipe is gradually reduced to a size slightly larger than the diameter of the stainless steel wire, and a gas-blocking material is installed inside the tail end; it can only be used for the stainless steel wire to pass out , not for the reducing gas to flow out).

So that the protective gas can only flow out toward the direction of the wire inlet pipe section, and cannot flow out toward the wire outlet pipe section.

The reducing gas is hydrogen and nitrogen decomposed by the ammonia decomposition furnace. Nitrogen is an inert gas (hydrogen and nitrogen do not need to be separated, and in the annealing furnace tube section, there is no condition for resynthesis into ammonia after decomposition), which can protect stainless steel Silk. Alternatively, the reducing gas is relatively pure (high purity and not easy to explode) alkane gas (higher combustion value, better safety than hydrogen, and relatively stable chemical properties, less active than alkenes and alkynes); the preferred alkane gas is butane , the combustion value of butane is higher than that of other common reducing gases (hydrogen, carbon monoxide, methane, ethane, propane, ethylene, propylene, butene, and acetylene. Although the combustion value of pentane is higher than that of butane, it is liquid at room temperature and cannot As a reducing protective gas, it is not considered), much higher than hydrogen, and the heat generated by its instantaneous combustion can make the stainless steel wire rapidly rise in temperature by 150-350°C during the second heating process described below. When the reducing gas comes into contact with air, it can be ignited and burned, heating the wire outlet pipe section, and transferring heat to the stainless steel wire.

The above-mentioned reducing gas, at high temperature in the annealing pipe section, can give the surface of the stainless steel wire hydrogen permeation, and the surface hydrogenation treatment is carried out while the internal annealing heat treatment is carried out.

At the same time, the reducing gas higher than the atmospheric pressure discharged after reverse walking can prevent the oxygen in the atmosphere from entering the wire-feeding steel pipe from the opening, ensuring that the stainless steel wire heated to a higher temperature will not be oxidized and reduced by contact with oxygen. The inert gas is retrograde to block the entry of oxygen, while the oxygen is consumed by hydrogen combustion, further ensuring that the stainless steel wire will not be oxidized in the wire feeding tube.

When the protective reducing atmosphere (hydrogen or alkane gas) is protected by an inert atmosphere (nitrogen) or the purity is high, it does not need to be protected by an inert gas, and it will not explode or oxidize.

The water vapor and nitrogen generated by hydrogen or alkane gas combustion heating can be directly evacuated, or the heat can be used for preheating in an oven.

The oven pipe section is preset and passes through the oven. The high-temperature flue gas in the oven preheats the oven pipe section, and transfers the heat of the pipe wall to the stainless steel wire running in the oven pipe section, so that the stainless steel wire is heated for the first time. Heating (temperature 100-150°C), the water vapor on the surface is dried, and the stainless steel wire does not contact the corrosive fume in the oven.

The bare section is a shorter section, so that the stainless steel wire is emitted into the atmosphere by the water vapor generated by the first heating, and because the first preheating temperature is lower, the stainless steel wire will not be oxidized by the oxygen in the surrounding air.

The diameter of the wire feeding steel pipe is about 5-12 times the diameter of the stainless steel wire, preferably 5-6 times (the amount of reducing gas is too small, and the heat generated by combustion is not enough; when it is too large, the amount of combustion gas is too large , more resources are consumed, and tempering is easy to occur, which affects the safety of the system; and the burning temperature is too high, which is not conducive to staged heating to make the metallographic structure of stainless steel wire tend to be reasonable).

The reducing gas is discharged, ignited at the air outlet, and reacts with the oxygen in the air to generate heat, so that the stainless steel wire is heated for the second time, and the instantaneous heating of the stainless steel wire on the line rises to the second stage temperature required for annealing (controlled reduction The air pressure of the reactive gas is 2-10atm, the diameter of the stainless steel wire is 1-2.5mm, and the walking speed of the stainless steel wire is 1-5 m/s. The amount of the reducing gas and the combustion value, as well as the specific heat of the stainless steel wire travel per unit time. Quality and other parameters, combined with the preheating temperature of the stainless steel wire in the oven pipeline, can be calculated and controlled to heat the stainless steel wire for the second time by 100-400°C, reaching a temperature of 200-550°C).

Since the diameter of the stainless steel wire for welding is already relatively thin after rough drawing (the temperature of the second heating and annealing is easier to control accurately), it passes through the moment of hydrogen or alkane gas combustion (the time it takes to travel in the wire feeding tube). Generating temperature can reduce the time and heat required for heating in the annealing furnace, reducing the production cycle.

The stainless steel wire continues to walk in the annealing furnace tube section, and is heated by the fuel in the annealing furnace (such as gas or a mixture of natural gas and air) from the outside of the annealing furnace steel pipe (the third heating), so that the stainless steel wire passing through it continues to heat up to 1000 -1100℃, reaching the highest temperature required for stainless steel wire annealing, and realizing the annealing process.

Then, the stainless steel wire passes through the cooling pipe section set in the cooling pool (where a large amount of aqueous solution is stored), and is rapidly cooled down to normal temperature. Finally, it is drawn out from the outlet of the silk outlet pipe section.

The waste gas generated by the combustion of coal gas or natural gas in the annealing furnace flows back into the oven through the waste gas pipe, and the residual heat is used to preheat the oven pipe section in the oven (do not directly contact the stainless steel wire to avoid corrosion of the stainless steel wire by high-temperature waste gas), and then The stainless steel wire walking in the oven tube section is preheated (first heating) to a certain initial temperature; then it receives the heat of the subsequent second and third heating, and the superposition of heat makes the stainless steel wire reach the high temperature required for annealing, waste heat Make full use of it to reduce the consumption of hydrogen (ammonia) or alkane gas. After the waste heat in the oven is used, the flue gas is directly emptied from the exhaust pipe above the oven, which can reduce the emission of waste heat and basically does not affect the ambient temperature of the workshop.

Beneficial effect:

The stainless steel wire annealing heating of the present invention is divided into three stages: (1) The oven preheats the oven pipe section for the first time, so that the water of the stainless steel wire in the cleaning of the previous process evaporates; (2) The exposed section and the wire feeding pipe section are exposed , ignite the reducing gas coming out of the air outlet in the tube and heat it, and the stainless steel wire is heated for the second time; (3) The steel section of the annealing furnace is heated, and the fuel such as gas is heated under the tube, and the heat is transferred to the stainless steel wire inside, so that the heating The temperature reaches 1000-1100°C.

Three-stage heating makes the temperature increase step by step, and the metallographic structure of the annealed stainless steel wire is better, which is convenient for the subsequent fine wire drawing process (it can be drawn again to a diameter of 0.3mm-1.2mm, especially 0.3-0.6mm), traditional The annealing process cannot draw to such a fine diameter.

In the present invention, the annealing furnace with high price and large volume (steel wire coils placed) is not used, but independent wire feeding pipes and annealing furnace steel pipes are used instead of the annealing furnace hearth to reduce equipment investment costs.

The annealed stainless steel wire walks to the cooling pipe section and is immersed in the aqueous solution of the cooling pool (not air cooling or inert gas cooling), which reduces the time and heat source consumed by cooling, so that the wire drawing production can be carried out continuously without stopping, and the fuel cost is low.

The stainless steel wire annealing system equipment of the present invention has simple structure, ingenious design and low use cost. Drawing production efficiency is high, safe and reliable, energy saving and environmental protection.

The hydrogen or alkane gas in the ammonia decomposition gas has four purposes: burning to generate the high temperature required for annealing; maintaining the reducing atmosphere in the wire feeding tube; consuming the oxygen at the opening and isolating oxygen from entering the high-temperature annealing tube section to avoid damage to the stainless steel wire Oxidation and corrosion; the formation of water vapor or carbon dioxide can be directly discharged into the atmosphere without environmental pollution.

The secondary use of the heat source generated by the gas in the annealing furnace further saves fuel consumption and reduces heat emissions. The cooling water solution is not in direct contact with the stainless steel wire, so it is not easy to pollute the finished product, and it is not easy to leak to ensure a good production environment in the workshop.

Description of drawings

Fig. 1 is a kind of system three-dimensional structure schematic diagram of the present invention;

Fig. 2 is a schematic cross-sectional structure diagram of a steel wire of the present invention in several pipe sections.

In the figure, 1-steel wire; 2-oven; 3-bare section; 6-wire outlet pipe section; 8-reducing gas pipe; 9-annealing furnace pipe section; 10-wire inlet pipe section; 11-exhaust pipe; 12-air outlet 13-exhaust gas pipe; 14-gas pipe; 15-air pipe; 16-blocking material; 20-flame; 22-oven pipe section.

Detailed ways

Embodiment one:

The graded heating annealing oxygen barrier system of the stainless steel wire drawing machine shown in Figure 1 has a plurality of parallel stainless steel wires 1. According to the running route, each stainless steel wire 1 passes through the respective oven pipe section 22, the exposed section 3, and the wire feeding in sequence. Pipe section 10, annealing furnace pipe section 9, cooling pipe section, wire outlet pipe section 6.

The wire inlet pipe section 10, the annealing furnace pipe section 9, the cooling pipe section and the wire outlet pipe section 6 are interconnected pipelines.

A pipeline 8 of reducing gas hydrogen is connected between the cooling pipe section and the annealing furnace pipe section 9, and the inlet of the wire feeding pipe section 10 is provided with an opening for the reducing gas to flow out, for the reducing gas to discharge, and to be connected with the oxygen in the air. The reaction is ignited at the air outlet 12 to generate heat, which heats the tube wall, so that the stainless steel wire 1 is heated for the second time, and the instantaneous heating of the stainless steel wire 1 on-line rises to the second stage temperature required for annealing. The water vapor produced by hydrogen combustion is directly emptied without pollution.

The outlet of the wire outlet pipe section 6 is a beam mouth, which can only be used for the stainless steel wire 1 to pass out, but not for the reducing gas to flow out.

Embodiment two:

as shown in picture 2,

In Example 1, the reducing gas used in the second heating was replaced by n-butane.

By controlling the walking speed of the steel wire 1, the diameter data of the wire feeding pipe 10, the diameter data of the steel wire 1, the pressure or flow rate of the butane gas, etc., the three sections of the steel wire can be controlled to be heated step by step, and the final temperature reaches the temperature required for annealing.

The formula for calculating the heat generated when n-butane is burned: Q=Cm1ΔT=m2q (or V2q, depending on the q unit).

Where C is the specific heat of the stainless steel wire 1 460J/kg*℃, m1 is the quality of the stainless steel wire 1 running within the length of the wire feeding pipe section 10 and the converted part of the pipe wall, and ΔT is the temperature raised by the second section of heating the stainless steel wire 1; m2 is the mass of n-butane gas flowing out of the length of the wire feeding pipe section 10, V2 is the volume of n-butane gas, and q is the combustion value of n-butane.

The inner diameter of the wire-feeding steel pipe is about 6-10mm (wall thickness 0.4-0.6mm), the length of the wire-feeding pipe section 10 is 100-200mm, the pressure of n-butane gas is 2-5atm (pressure at normal temperature), the diameter of the stainless steel wire 1 1.0-1.5mm, the speed of stainless steel wire 1 is 1-3 m/s, through the reducing gas and various parameters of stainless steel wire 1, heat transfer efficiency, and the wall of the wire feeding pipe section 10 is continuously heated (some heat flow is lost, It can be assumed that 1/3 of the tube wall needs to be heated continuously, and the rest of the tube wall is basically constant temperature) and its heat loss and other factors.

Applying the Delacron equation PV=nRT of gas again, it can be approximated to calculate that the temperature of the stainless steel wire 1 is raised by 150-250° C. by the second heating.

In addition to the temperature after the first preheating, the temperature of the stainless steel wire 1 in the wire feeding tube section 10 reaches 200-400°C, and the annealing heating in the third section only needs to increase the temperature by 600-800°C to reach the required temperature of 1000°C for annealing. -1100°C, the gas consumed for the third heating can be saved.

Moreover, the staged heating optimizes the metallographic structure of the stainless steel wire 1 , the grains are finer and evenly arranged, and after cooling, it can be finely drawn, and the diameter of the drawn wire can reach about 0.4-0.6mm.

Claims (5)

1. A graded heating annealing oxygen barrier system for a stainless steel wire drawing machine, with a plurality of parallel stainless steel wires, characterized in that: according to the running route, each stainless steel wire (1) passes through its own independent and interconnected oven pipe section (22 ), bare section (3), wire feeding pipe section (10), annealing furnace pipe section (9), cooling pipe section, wire outlet pipe section (6); oven pipe section (22) passes through the oven (2), and annealing furnace pipe section (9) passes through Annealing furnace; the outlet of the wire outlet pipe section (6) is a beam mouth, only for the stainless steel wire (1) to go out; Between the cooling pipe section and the annealing furnace pipe section (9), there is a reducing gas pipeline (8) with a pressure higher than atmospheric pressure, and the reducing gas flows in the opposite direction to the running direction of the stainless steel wire (1), so that the stainless steel wire (1) During the annealing temperature heat treatment process, the hydrogenation heat treatment is carried out at the same time, and the reducing gas then flows out from the opening of the connection between the wire feeding tube section (10) and the bare section (3); The stainless steel wire (1) is heated and dried by the oven (2) for the first time in the oven pipe section (22), and is heated to the annealing temperature by the gas in the annealing furnace pipe section (9) for the third time. 2. The stainless steel wire drawing machine graded heating annealing oxygen barrier system according to claim 1, characterized in that: the reducing gas discharged from the opening is ignited to consume the oxygen in the opening, and the pressure of the reducing gas (8) prevents The rest of the oxygen enters the annealing furnace tube section (9), and at the same time ignites the stainless steel wire (1) for the second heating. 3. The stainless steel wire drawing machine graded heating annealing oxygen barrier system according to claim 1, characterized in that: the reducing gas is n-butane; the stainless steel wire (1) is heated to 100-150°C for the first time, and the second time Heating to 200-550°C, and heating to 1000-1100°C for the third time. 4. The stainless steel wire drawing machine graded heating annealing oxygen barrier system according to claim 1, 2 or 3, characterized in that: the tail end of the wire outlet pipe (6) is also in the shape of a tapered tube with a gradually decreasing inner diameter, and there is preset therein Blocking material (16). 5. The stainless steel wire drawing machine graded heating annealing oxygen barrier system according to claim 1, 2 or 3, characterized in that: the waste gas generated by the ignition of the reducing gas flows into the front oven (2) through the waste gas pipe (13) , preheating the oven pipe section (22) in the oven (2), and the heat of the oven pipe section (22) is transferred to the stainless steel wire (1) passing therein for the first heating.

Images