An energy-saving processing method for a mabe heat treatment continuous production line

Abstract

The application relates to an energy-saving processing method for a marbain heat treatment continuous production line, when switching between martensite and bainite quenching processes, as long as the quenching heating temperature meets the heating temperature of the quenched and tempered product, the quenched and tempered product does not need to wait for the salt tank salt temperature to rise or drop to the temperature, can continuously enter the salt tank for quenching cooling by using the instant salt temperature on the production line, the quenched and tempered product is processed by using the interval, the lower limit temperature of the quenching medium is lowered and the upper limit temperature of the forced quenching medium is raised, the heat released when the workpiece is quenched is fully utilized to heat the quenching medium, the natural heat dissipation of the quenching medium is utilized, and the energy consumption for forced cooling of the quenching medium is reduced. This heat treatment process can compensate for the idle capacity of the previous equipment, fully release the production capacity of the equipment, and greatly reduce the energy consumption of the quenching heating furnace and the salt tank and other equipment.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology, specifically to an energy-saving processing method for a continuous heat treatment production line in Mapei. Background Technology

[0002] When processing bearing parts using a Marbe heat treatment continuous furnace production line, salt bath quenching allows for switching between martensitic and bainitic processes to meet the different heat treatment requirements of the product. During this switching process, in addition to raising or lowering the heating temperature of the quenching furnace, the salt temperature of the quenching cooling bath also needs to be adjusted. For example, the commonly used heating temperature for martensitic quenching is 830-850℃ (lower limit for GCr15SiMn, upper limit for GCr15), with a quenching cooling salt temperature of 180℃; the commonly used heating temperature for bainitic quenching is 875℃, with a quenching cooling salt temperature of 200℃. Conventionally, during the switching between martensitic and bainitic quenching, the product should only be placed in the furnace after both the quenching heating temperature and the quenching cooling salt temperature meet the process requirements. This waiting process is equivalent to the equipment consuming energy in vain. The equipment's quenching heating furnace heats up by about 20°C per hour, while the salt tank heats up by about 3°C ​​per hour. Obviously, the salt tank consumes more energy than the quenching heating furnace. Waiting with an empty furnace not only affects the equipment's production capacity but also brings huge energy waste. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the existing defects and provide an energy-saving processing method for a continuous production line of Marbe heat treatment. This method solves the adverse consequences caused by switching between conventional martensitic and bainitic quenching processes, improves equipment utilization, increases equipment output, and reduces energy consumption, thus effectively solving the problems in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: an energy-saving processing method for a continuous production line of Marpe heat treatment, characterized in that: during the transition period between martensitic quenching and bainitic quenching, tempered products are processed using the production line; wherein the material of the tempered products is one of 42CrMo, 40# or 45# steel, and the hardness after tempering is required to be 250-350 HB; the quenching heating temperature range of the tempered products is 850-875℃, and the salt temperature range of the quenching cooling salt bath is 180-200℃;

[0005] When switching from martensitic quenching to bainitic quenching, the following steps are adopted: a. After martensitic quenching, set the temperature of the area near the furnace inlet of the heating furnace to 860℃ and the temperature of the remaining area to 850℃. After the furnace temperature stabilizes, first process the tempered products with a quenching heating temperature of 850℃ in the furnace; at the same time, set the target salt temperature of the quenching cooling salt bath to 200℃ and start heating. b. After the 850℃ tempered product is heated, set the temperature control instrument of the entire heating furnace to 875℃, and continuously feed the tempered product into the furnace online during the process of the furnace temperature rising from 850℃ to 875℃. c. The tempered product heated in steps a and b does not need to wait for the salt bath to reach the target temperature. It can be quenched and cooled directly using the current real-time temperature of the salt bath. The heat carried by the hot tempered product itself is used to accelerate the heating process of the salt bath from 180°C to 200°C. d. When the furnace temperature reaches 875℃ and the salt temperature in the salt bath reaches 200℃, stop feeding the tempered products into the furnace and switch to processing the bainitic quenched products. When switching from bainitic quenching to martensitic quenching, the following steps are adopted: a. Set the target temperatures of the heating furnace and the quenching and cooling salt bath to 830-850℃ and 180℃ respectively, and start cooling the quenching and cooling salt bath. b. Immediately after the last bainitic quenched product, the tempered product is directly put into a heating furnace at 875℃, and the tempered product is continuously fed into the furnace online for processing as the furnace temperature decreases from 875℃ to 830-850℃. c. The tempered product heated in step b does not need to wait for the salt bath to drop to the target temperature. It can be quenched and cooled directly using the current real-time temperature of the salt bath until the salt temperature in the salt bath drops to 180°C. d. When the furnace temperature drops to 850℃, stop processing the tempered products; if the subsequent martensitic products need to be quenched at 850℃, switch immediately; if they need to be quenched at 830℃, continue to cool down to 830℃ before switching.

[0006] Preferably, before the tempered product is placed into the quenching and cooling salt bath, the difference between the current temperature and the target temperature of the quenching and cooling salt bath is monitored in real time; if the difference is greater than 15°C, the loading density or single batch weight of the tempered product subsequently placed into the furnace is controlled.

[0007] Preferably, the total mass of conditioning products arranged during each switching transition period It is expressed as follows: ;

[0008] in, The specific heat capacity of the medium in the quenching and cooling salt bath. The effective volume of the quenching and cooling salt bath. To determine the density of the medium in the quenching and cooling salt bath, This represents the temperature difference between the target temperature rise and fall of the quenching and cooling salt bath. For the specific heat capacity of the conditioned product, The coefficient is the average temperature drop of the tempered product. This is the heat loss compensation factor, with a value ranging from 1.1 to 1.3.

[0009] Preferably, during the quenching and cooling process of the tempered product, multi-point temperature data at different depths in the quenching and cooling salt bath are collected in real time, and the entry speed or residence time of the tempered product in the bath is dynamically adjusted based on the multi-point temperature data.

[0010] Preferably, the heating furnace is divided into a preheating chamber and a zoned heating chamber, with the preheating chamber located near the furnace feed inlet.

[0011] Preferably, the partitioned heating chamber is divided into 3-5 independent temperature control zones, and the temperature of each zone is set to a stepped distribution according to the product's direction of travel, with an increasing gradient during the heating switching phase and a decreasing gradient during the cooling switching phase.

[0012] Compared with existing technologies, the advantages of this invention are: During the transition between two processing methods, tempered products are processed. As long as the quenching heating temperature meets the heating temperature of the tempered product, the tempered product after heating does not need to wait for the salt temperature in the salt bath to rise or fall; it can be continuously fed into the salt bath for quenching and cooling using the instantaneous salt temperature on the production line. Especially during the transition from martensitic to bainitic quenching, the tempered product processing introduces its own heat into the quenching salt bath, promoting a rapid rise in the salt temperature. This heat treatment technology, on the one hand, compensates for the idle capacity caused by previous equipment downtime, allowing for full release of equipment capacity; on the other hand, it significantly reduces the energy consumption of quenching furnaces and salt baths during the transition between martensitic and bainitic quenching processes. Attached Figure Description

[0013] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0014] The present invention can be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "front", "rear", "left", "right" indicating the orientation or positional relationship, they are only corresponding to the drawings of this application for the convenience of describing the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation.

[0015] Please see Figure 1This invention provides a technical solution: an energy-saving processing method for a continuous Marble heat treatment production line, characterized in that: during the transition period between martensitic quenching and bainitic quenching, the production line processes tempered products; wherein the material of the tempered products is one of 42CrMo, 40# or 45# steel, and the hardness after tempering is required to be 250-350 HB; the quenching heating temperature range of the tempered products is 850-875℃, and the salt temperature range of the quenching cooling salt bath is 180-200℃;

[0016] I. When switching from martensitic quenching to bainitic quenching, the following steps shall be adopted: a. After martensitic quenching, set the temperature of the area near the furnace inlet of the heating furnace to 860℃ and the temperature of the remaining area to 850℃. After the furnace temperature stabilizes, first process the tempered products with a quenching heating temperature of 850℃ in the furnace; at the same time, set the target salt temperature of the quenching cooling salt bath to 200℃ and start heating. b. After the 850℃ tempered product is heated, set the temperature control instrument of the entire heating furnace to 875℃, and continuously feed the tempered product into the furnace online during the process of the furnace temperature rising from 850℃ to 875℃. c. The tempered product heated in steps a and b does not need to wait for the salt bath to reach the target temperature. It can be quenched and cooled directly using the current real-time temperature of the salt bath. The heat carried by the hot tempered product itself is used to accelerate the heating process of the salt bath from 180°C to 200°C. d. When the furnace temperature reaches 875℃ and the salt temperature in the salt bath reaches 200℃, stop feeding the tempered products into the furnace and switch to processing the bainitic quenched products.

[0017] II. When switching from bainitic quenching to martensitic quenching, the following steps shall be adopted: a. Set the target temperatures of the heating furnace and the quenching and cooling salt bath to 830-850℃ and 180℃ respectively, and start cooling the quenching and cooling salt bath. b. Immediately after the last bainitic quenched product, the tempered product is directly put into a heating furnace at 875℃, and the tempered product is continuously fed into the furnace online for processing as the furnace temperature decreases from 875℃ to 830-850℃. c. The tempered product heated in step b does not need to wait for the salt bath to drop to the target temperature. It can be quenched and cooled directly using the current real-time temperature of the salt bath until the salt temperature in the salt bath drops to 180°C. d. When the furnace temperature drops to 850℃, stop processing the tempered products; if the subsequent martensitic products need to be quenched at 850℃, switch immediately; if they need to be quenched at 830℃, continue to cool down to 830℃ before switching.

[0018] It is understandable that during the transition between two processing methods, tempered products are processed. As long as the quenching heating temperature meets the heating temperature of the tempered product, the tempered product after heating does not need to wait for the salt temperature in the salt bath to rise or fall. It can be continuously fed into the salt bath for quenching and cooling using the instantaneous salt temperature on the production line. Especially during the transition from martensitic to bainitic quenching, due to the intervention of tempered product processing, the tempered product exiting the heating furnace carries its own heat into the quenching salt bath, promoting a rapid rise in the salt temperature of the quenching bath. This heat treatment technology, on the one hand, makes up for the idle capacity caused by previous equipment idleness, allowing the equipment capacity to be fully released; on the other hand, it can significantly reduce the energy waste of equipment such as quenching heating furnaces and salt baths during the transition between martensitic and bainitic quenching processes.

[0019] Furthermore, before the tempered product is placed into the quenching and cooling salt bath, the difference between the current temperature and the target temperature of the quenching and cooling salt bath is monitored in real time; if the difference is greater than 15°C, the loading density or single batch weight of the tempered product is controlled, thereby stabilizing the temperature of the salt bath and significantly reducing external heating / cooling intervention.

[0020] Furthermore, the total mass of conditioning products arranged during each switching transition period It is expressed as follows: ;

[0021] in, The specific heat capacity of the medium in the quenching and cooling salt bath. The effective volume of the quenching and cooling salt bath. To determine the density of the medium in the quenching and cooling salt bath, This represents the temperature difference between the target temperature rise and fall of the quenching and cooling salt bath. For the specific heat capacity of the conditioned product, The coefficient is the average temperature drop of the tempered product. The heat loss compensation factor is set at a value of 1.1-1.3; a quantitative model for the dosage of conditioning products based on thermodynamic conservation is proposed to provide a calculation basis for energy-saving operation and ensure that the salinity temperature is accurately met.

[0022] Furthermore, during the quenching and cooling process of tempered products, multi-point temperature data at different depths in the quenching and cooling salt bath are collected in real time, and the entry speed or residence time of the tempered products in the bath is dynamically adjusted based on the multi-point temperature data to ensure the uniformity of the cooling rate of the product cross section, meet the requirements of the 250-350 HB hardness range, and avoid stress concentration in the structure caused by local overcooling or uneven cooling.

[0023] Furthermore, the heating furnace is divided into a preheating chamber and a zoned heating chamber, with the preheating chamber located near the furnace feed inlet. Specifically, the zoned heating chamber is divided into 3-5 independent temperature control zones, with the temperature of each zone set in a stepped distribution according to the product's direction of travel. During the temperature rise transition phase, the temperature exhibits an increasing gradient (e.g., 850→860→870→875℃), and during the temperature fall transition phase, the temperature exhibits a decreasing gradient (e.g., 875→865→855→850℃), reducing thermal stress on the product and accelerating the overall furnace temperature response.

[0024] The parts of this invention not described in detail are prior art. It will be apparent to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and are intended to encompass all changes falling within the meaning and scope of equivalents in the content of this invention.

Claims

1. An energy-saving processing method for a continuous heat treatment production line in Mapé, characterized in that: During the transition period between martensitic and bainitic quenching, tempered products are processed using a production line. The material of the tempered products is one of 42CrMo, 40#, or 45# steel, and the hardness after tempering is required to be 250-350 HB. The quenching heating temperature range of the tempered products is 850-875℃, and the salt temperature range of the quenching cooling salt bath is 180-200℃. When switching from martensitic quenching to bainitic quenching, the following steps are adopted: a. After martensitic quenching, set the temperature of the area near the furnace inlet of the heating furnace to 860℃ and the temperature of the remaining area to 850℃. After the furnace temperature stabilizes, first process the tempered products with a quenching heating temperature of 850℃ in the furnace; at the same time, set the target salt temperature of the quenching cooling salt bath to 200℃ and start heating. b. After the 850℃ tempered product is heated, set the temperature control instrument of the entire heating furnace to 875℃, and continuously feed the tempered product into the furnace online during the process of the furnace temperature rising from 850℃ to 875℃. c. The tempered product heated in steps a and b does not need to wait for the salt bath to reach the target temperature. It can be quenched and cooled directly using the current real-time temperature of the salt bath. The heat carried by the hot tempered product itself is used to accelerate the heating process of the salt bath from 180°C to 200°C. d. When the furnace temperature reaches 875℃ and the salt temperature in the salt bath reaches 200℃, stop feeding the tempered products into the furnace and switch to processing the bainitic quenched products. When switching from bainitic quenching to martensitic quenching, the following steps are adopted: a. Set the target temperatures of the heating furnace and the quenching and cooling salt bath to 830-850℃ and 180℃ respectively, and start cooling the quenching and cooling salt bath. b. Immediately after the last bainitic quenched product, the tempered product is directly put into a heating furnace at 875℃, and the tempered product is continuously fed into the furnace online for processing as the furnace temperature decreases from 875℃ to 830-850℃. c. The tempered product heated in step b does not need to wait for the salt bath to drop to the target temperature. It can be quenched and cooled directly using the current real-time temperature of the salt bath until the salt temperature in the salt bath drops to 180°C. d. When the furnace temperature drops to 850℃, stop processing the tempered products; if the subsequent martensitic products need to be quenched at 850℃, switch immediately; if they need to be quenched at 830℃, continue to cool down to 830℃ before switching. Total mass of conditioning products arranged during each transition period It is expressed as follows: ； in, The specific heat capacity of the medium in the quenching and cooling salt bath. The effective volume of the quenching and cooling salt bath. To determine the density of the medium in the quenching and cooling salt bath, This represents the temperature difference between the target temperature rise and fall of the quenching and cooling salt bath. For the specific heat capacity of the conditioned product, The coefficient is the average temperature drop of the tempered product. This is the heat loss compensation factor, with a value ranging from 1.1 to 1.

3.

2. The energy-saving processing method for a continuous heat treatment production line of Mapei according to claim 1, characterized in that: Before the tempered product is placed into the quenching and cooling salt bath, the difference between the current temperature and the target temperature of the quenching and cooling salt bath is monitored in real time; if the difference is greater than 15°C, the loading density or single batch weight of the tempered product entering the furnace is controlled.

3. The energy-saving processing method for a continuous heat treatment production line of Mapei according to claim 1, characterized in that: During the quenching and cooling process of tempered products, multi-point temperature data at different depths in the quenching and cooling salt bath are collected in real time, and the entry speed or residence time of the tempered products in the bath is dynamically adjusted based on the multi-point temperature data.

4. The energy-saving processing method for a continuous heat treatment production line of Mapei according to claim 1, characterized in that: The heating furnace is divided into a preheating chamber and a zoned heating chamber, with the preheating chamber located near the furnace feed inlet.

5. An energy-saving processing method for a continuous heat treatment production line of Mapei according to claim 4, characterized in that: The partitioned heating chamber is divided into 3-5 independent temperature control zones. The temperature of each zone is set to a stepped distribution according to the product's direction of travel, with an increasing gradient during the heating switching phase and a decreasing gradient during the cooling switching phase.

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