A high wear-resistant lost foam casting hammer head and a synergistic heat treatment method thereof

Abstract

This invention discloses a high-wear-resistant lost foam casting hammerhead and its synergistic heat treatment method, relating to the field of hammerhead casting technology. The hammerhead is cast from low-alloy steel and high-manganese steel. First, a 1.5-2.0 mm thick coating is applied to the surface of the lost foam model, and the coating is dried at 40-50℃. Then, the dried lost foam model is combined with the gating and riser model to form a model cluster, which is fixed in a sand box for later use. Subsequently, the low-alloy steel and high-manganese steel are placed in a melting furnace for melting. First, the melted low-alloy steel casting is poured into shape, and then the melted high-manganese steel casting is poured into shape. After molding, it undergoes a heat treatment process. In the heat treatment process, this invention designs precise calculation logic for the three core processes of heating, holding, and cooling, realizing differentiated customization of heat treatment parameters for different areas of the hammerhead. This fundamentally solves the problem of mismatch between the existing overall process and the actual state of the workpiece, and provides a quantitative basis for the coordinated control of the entire process.

Description

Technical Field

[0001] This invention relates to the field of hammer casting technology, specifically to a high wear-resistant lost foam casting hammer and its synergistic heat treatment method. Background Technology

[0002] Lost foam casting is the mainstream process for producing high-wear-resistant hammerheads. Hammerheads produced using this method are characterized by high forming precision and good compositional uniformity, and are widely used in crushing equipment in industries such as mining, building materials, and metallurgy. To meet the high hardness and high toughness requirements of the hammerheads, heat treatment is the core process that determines their final performance and lifespan. Currently, most hammerhead heat treatment in the industry adopts an integrated process control, completing the heat treatment process through preset fixed temperatures, holding times, and cooling parameters. Some advanced production lines have introduced sensor detection and parameter calculation systems to set process parameters based on material grade and overall workpiece dimensions, providing a standardized control scheme for batch heat treatment of hammerheads and effectively supporting the large-scale production of lost foam casting hammerheads.

[0003] However, existing heat treatment parameter control methods still suffer from insufficient adaptability. On the one hand, they do not fully consider the differences in compositional gradients, residual stresses, and surface conditions in different regions during lost foam casting, making it difficult to match differentiated process parameters to the characteristics of different regions such as the hammerhead working surface, transition zone, and mounting holes. This can easily lead to insufficient local austenitization or grain overheating. On the other hand, the calculation of process parameters does not incorporate actual test data from multiple dimensions, such as carburized layer characteristics, grain growth process, and heat transfer conditions. This makes it difficult to achieve coordinated control of the entire heating, holding, and cooling process, and cannot simultaneously meet the needs of sufficient microstructure transformation and precise performance control, thus restricting further improvement in the performance of the hammerhead. Summary of the Invention

[0004] The purpose of this invention is to provide a high wear-resistant lost foam casting hammer and its synergistic heat treatment method, which solves the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high wear-resistant lost foam casting hammer head, comprising a mounting part, a striking part, and a transition part, wherein the transition part is located between the mounting part and the striking part, and the hammer head is cast from low alloy steel and high manganese steel.

[0006] Optionally, a 1.5-2.0mm thick coating is applied to the surface of the lost foam model, and the coating is dried at 40-50℃. The dried lost foam model is then combined with the gating and riser model to form a model cluster, which is fixed in a sand box for later use. Subsequently, low-alloy steel and high-manganese steel are placed in a melting furnace for melting. The molten low-alloy steel is first poured into a mold, and then the molten high-manganese steel is poured into a mold. After molding, a heat treatment process is performed to obtain a high-wear-resistant lost foam casting hammerhead.

[0007] This invention also provides a synergistic heat treatment method for a high wear-resistant lost foam casting hammerhead, comprising the following steps:

[0008] S1: Post-casting pretreatment: After the lost foam casting of the hammer head is naturally cooled to room temperature, it is shot blasted to remove most of the residual refractory coating and oxide scale, leaving a thin oxide layer of less than 0.5 mm to avoid excessive grinding and damage to the substrate;

[0009] S2: Parameter pre-calculation: The pre-treated hammerhead is transported to the inspection station, and data is collected synchronously through the integrated multi-sensor array. Then, the control system automatically calculates the austenitizing target temperature, optimal heat preservation time and target cooling rate of each area. At the same time, it automatically identifies abnormal areas with excessive residual coating and outputs cleaning prompts.

[0010] S3: Zoned heating: The hammerhead is sent into the zoned temperature-controlled heat treatment furnace. Based on the parameters output by the control system, different heating power is controlled for different zones. During the heating process, the temperature of each zone is monitored in real time by temperature sensors to ensure that the temperature error is controlled within ±5℃.

[0011] S4: Differentiated insulation: After each area reaches the target temperature, the insulation is carried out in zones according to the optimal insulation time output by the system, and surface decarburization is avoided during the insulation process;

[0012] S5: Zone quenching: After the heat preservation is completed, the hammer head is quickly transferred to the zone cooling station and zone quenching is performed according to the target value output by the control system.

[0013] S6: Low-temperature tempering treatment: After quenching, the hammer head is sent into a tempering furnace to eliminate residual quenching stress and obtain a matching structure with high hardness and high toughness.

[0014] Optionally, the control system includes a data acquisition module, a data preprocessing module, and a zone calculation module. The data acquisition module acquires multi-source detection data for each region of the hammerhead and divides the detection data into data related to austenitizing temperature calculation, holding time calculation, and cooling rate calculation. The data is then sent to the data preprocessing module for cleaning and standardization. The processed data is then input into the zone calculation module, which sequentially outputs the target heating temperature of the i-th region, the optimal holding time of the i-th region, and the target cooling rate of the i-th region, thereby achieving differentiated and precise control of the heat treatment process parameters for each region of the hammerhead.

[0015] Optionally, the partitioning calculation module includes a first partition, a second partition, and a third partition.

[0016] Optionally, the processing logic of the first module is as follows: First, the measured original carburized layer gradient difference is corrected for oxidation interference to eliminate the measurement error caused by the depletion of the surface oxide layer. Then, based on the material equilibrium austenitizing temperature, three adjustment items are sequentially added: surface carbon content compensation, carburizing gradient compensation, and residual stress correction. After obtaining the theoretical optimal temperature, the minimum value is taken from the upper limit of the temperature, and finally the target heating temperature of the i-th region is output.

[0017] Optionally, the processing logic of the second module is as follows: First, the emissivity interference correction is applied to the grain growth accumulation factor during the heating process to eliminate the temperature integration error caused by the surface emissivity deviation of the infrared temperature sensor. Then, the actual infrared emissivity of the i-th region is calculated based on the surface roughness. Finally, based on the basic heat preservation time, four adjustment items are sequentially added: temperature deviation compensation, carbide dissolution compensation, grain growth correction, and workpiece thickness compensation. After obtaining the theoretical optimal heat preservation time, the maximum value is taken from the lower limit of the time, and the optimal heat preservation time of the i-th region is finally output.

[0018] Optionally, the processing logic of the third module is as follows: First, calculate the residual thermal resistance of the original coating, then correct the thermal resistance of the residual coating for porosity interference, eliminate the thermal resistance calculation error caused by porosity differences, obtain the residual thermal resistance factor of the coating in the i-th region, restore the true thermal resistance of the residual coating, and then perform thermal resistance anomaly judgment to determine the target cooling rate of the i-th region through anomaly judgment.

[0019] Optionally, the processing logic for determining abnormal thermal resistance is as follows:

[0020] When the residual thermal resistance factor of the coating in region i exceeds the threshold, it is marked as condition B, and an abnormal prompt is triggered directly: "The residual coating is too thick. It is recommended to clean it and retest."

[0021] When the residual thermal resistance factor of the coating in region i does not exceed the threshold, it is marked as condition A. At this time, the basic cooling rate is obtained by dividing the phase change temperature range by the heat preservation time. Then, three adjustment items, namely medium heat transfer correction, service condition correction, and thermal resistance correction, are added in sequence to obtain the theoretical cooling rate. The minimum value is first taken with the upper limit value, and then the maximum value is taken with the lower limit value. Finally, the target cooling rate of region i is output.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] I. This invention obtains the true carburized layer gradient through oxide layer interference correction, and combines multi-dimensional compensation of surface carbon content, carburized gradient and residual stress. At the same time, it sets an upper limit constraint on austenitizing temperature, which can output differentiated target heating temperatures for different regions based on composition and stress state. This ensures that the carburized layer can complete austenite transformation from the surface to the interior, while avoiding excessive local temperature leading to coarse austenite grains. It achieves precise matching between austenitizing temperature and regional microstructure characteristics, and solves the problem of local underheating or overheating caused by traditional overall heating.

[0024] Second, this invention obtains the true grain growth accumulation factor through emissivity interference correction, and combines multi-factor coupling correction of temperature deviation, carbide content, grain growth degree and workpiece thickness. At the same time, it sets a lower limit constraint on the holding time, which can output differentiated holding time for different regions' heating process and structural characteristics. This ensures that the alloy carbides are fully dissolved and the austenite composition is homogenized, while avoiding excessive grain growth caused by excessive holding time, thus achieving dynamic matching between holding time and phase transformation process.

[0025] Third, this invention obtains the true residual thermal resistance of the coating through porosity interference correction. Combined with multi-parameter linkage calculation of phase transformation temperature range, service conditions and heat transfer conditions, and setting upper and lower limits of cooling rate constraints, it can output differentiated cooling rates for different surface conditions and performance requirements of different regions. This ensures that the supercooled austenite is fully transformed into martensite while avoiding the risk of quenching cracking caused by excessive cooling rate. It achieves the unity of microstructure control and quality control in the cooling process and solves the problem of unqualified microstructure or high risk of cracking caused by uniform cooling strategy. Attached Figure Description

[0026] Figure 1 This is a logic diagram of the heat treatment process of the present invention;

[0027] Figure 2 This is a casting process diagram of the present invention;

[0028] Figure 3 This is a schematic diagram of the hammerhead of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example: See Figure 2 and Figure 3The present invention provides a high wear-resistant lost foam casting hammer head, comprising a mounting part, a striking part and a transition part, wherein the transition part is located between the mounting part and the striking part, and the hammer head is cast from low alloy steel and high manganese steel.

[0031] Specifically, a 1.5-2.0mm thick coating is applied to the surface of the lost foam model, and the coating is dried at 40-50℃. The dried lost foam model is then combined with the gating and riser model to form a model cluster, which is fixed in a sand box for later use. Low-alloy steel and high-manganese steel are placed in a melting furnace for melting. First, the melted low-alloy steel is poured into a mold, and then the melted high-manganese steel is poured into a mold. After molding, a heat treatment process is performed to obtain a high-wear-resistant lost foam casting hammerhead.

[0032] Among them, see Figures 1 to 3 A synergistic heat treatment method for a high wear-resistant lost foam casting hammerhead includes the following steps:

[0033] S1: Post-casting pretreatment: After the lost foam casting of the hammer head is naturally cooled to room temperature, it is shot blasted to remove most of the residual refractory coating and oxide scale, leaving a thin oxide layer of less than 0.5 mm to avoid excessive grinding and damage to the substrate;

[0034] S2: Parameter pre-calculation: The pre-treated hammerhead is transported to the inspection station, and data is collected synchronously through the integrated multi-sensor array. Then, the control system automatically calculates the austenitizing target temperature, optimal heat preservation time and target cooling rate of each area. At the same time, it automatically identifies abnormal areas with excessive residual coating and outputs cleaning prompts.

[0035] Specifically, the control system includes a data acquisition module, a data preprocessing module, and a zone calculation module. The acquisition module obtains multi-source detection data from various regions of the hammerhead and sends it to the data preprocessing module for cleaning and standardization. The processed data is then input to the zone calculation module, which sequentially outputs the target heating temperature T for the i-th region. target,i The optimal heat preservation time t for the i-th region hold,i and the target cooling rate v of region i cool,i This allows for precise and differentiated control of heat treatment process parameters in different areas of the hammerhead.

[0036] Furthermore, the data acquisition module categorizes the detection data into three types based on function: data related to austenitizing temperature calculation, data related to holding time calculation, and data related to cooling rate calculation. All sensors are equipped with high-temperature resistant protection devices and are integrated into the detection station of the heat treatment production line. All data acquisition is completed before the hammer enters the heating furnace, and the acquisition process does not affect the normal operation rhythm of the production line.

[0037] Specifically, the data related to the austenitizing temperature calculation includes the gradient difference ΔC of the original carburized layer in the i-th region of the hammerhead, obtained directly from the layered ablation scan of the i-th region using a LIBS (laser-induced breakdown spectroscopy) composition sensor. g,i,raw The surface morphology of the i-th region of the hammerhead is scanned using a laser confocal surface scanning sensor, and the thickness δ of the oxide layer on the surface of the i-th region is directly measured using the step method. ox,i The surface carbon content C of the i-th region of the hammerhead was directly acquired by performing a single scan of the surface layer of the i-th region using a LIBS composition sensor. surf,i The i-th region of the hammerhead was subjected to non-destructive testing using an ultrasonic stress detector. The residual tensile stress σ in the i-th region was calculated based on the correlation between ultrasonic velocity and stress. res,i .

[0038] It also includes the material equilibrium austenitizing transformation temperature T. Ae3 Surface carbon content compensation coefficient α1, carburizing gradient compensation coefficient α2, residual stress correction coefficient α3, and the highest offset threshold T for austenitizing temperature. Ae3_max_offset Carbon depletion coefficient of oxide layer k ox LIBS sensor single scan depth δ scan,i The above general parameters are pre-configured and stored in the database according to the material grade of the hammerhead. For high-manganese steel and other materials with high overheat sensitivity, the T... Ae3_max_offset Use 80℃ for low alloy steel and 50℃ for low alloy steel. Other parameters are pre-calibrated through material thermophysical property tests.

[0039] Specifically, the data related to the heat preservation time calculation includes the surface roughness R of the i-th region of the hammerhead, which is directly measured by scanning the surface morphology of the i-th region using a laser confocal surface scanning sensor. a,i The heating process temperature sequence T(t) is obtained by real-time temperature acquisition of the i-th region of the hammer head using an infrared temperature sensor. The average temperature T of the i-th region before heating to the target temperature is calculated by averaging the acquired temperature sequence through a sliding window. avg,i The composition of the i-th region of the hammerhead is scanned using a LIBS composition sensor, and the chromium content (Cr) of the i-th region is directly collected. i The hammerhead is scanned in three dimensions using a 3D structured light scanning sensor, and the effective thickness d of the i-th region of the workpiece is calculated using an equivalent thickness algorithm. eff,i .

[0040] It also includes the lower limit temperature T of the pearlite transformation of the material. Ae1 The basic insulation time t of the i-th region base,i Temperature deviation compensation coefficient β1, carbide solubility coefficient β2, grain accumulation correction coefficient β3, workpiece effective thickness correction coefficient β4, minimum holding time coefficient t hold_min_ratio(Pre-calibrated to 0.6), carbon content deviation compensation coefficient k C The target optimal surface carbon content C opt Emissivity correction factor k emis The default emissivity ε of the infrared temperature sensor set The above general parameters are configured in advance and stored in the database according to the heat treatment process specifications.

[0041] Specifically, the data related to the cooling rate calculation includes the surface morphology scan of the i-th region of the hammerhead using a laser confocal surface scanning sensor, and the directly measured thickness δ of the residual refractory coating on the surface of the i-th region. coat,i The surface morphology of the i-th region of the hammerhead is scanned by a laser confocal sensor, and the porosity P of the residual coating in the i-th region is calculated based on statistical analysis of grayscale distribution. coat,i The percentage of working impact frequency f in the i-th region is obtained by directly exporting historical operating data from the crushing equipment's PLC system. imp,i .

[0042] It also includes the martensitic transformation termination temperature T of the material. Mf critical cooling rate v for martensitic transformation lower Critical cooling rate v for quenching cracking upper Cooling medium heat transfer correction factor γ1, impact load factor γ2, thermal resistance correction factor γ3, coating thermal resistance anomaly threshold R th The thermal conductivity λ of dense refractory coating coat Coating porosity correction factor k por The above general parameters are pre-configured and stored in the database according to the type of cooling medium and the grade of material.

[0043] Furthermore, the partitioning calculation module includes a first section. During processing, the first section first corrects for oxidation interference in the original carburized layer gradient difference measured by the LIBS sensor, eliminating measurement errors caused by surface oxide layer depletion. The carburized layer gradient difference ΔC in the i-th region... g,i,corr The correction logic is as follows:

[0044]

[0045] Where, δ ox,i / δ scan,i The oxide layer thickness represents the proportion of the depth in a single LIBS scan, reflecting the degree of influence of the oxide layer on the measurement results; multiplied by the oxide layer carbon depletion coefficient k. ox The total interference ratio was then obtained, and the effective proportion of the measured value was obtained by subtracting this ratio from 1. Since oxide layer depletion leads to a lower measured value than the true value (the two are inversely proportional), a division method was used for correction to reverse the true gradient distribution of the carburized layer, k. oxThe parameters are pre-calibrated and range from 0.1 to 0.3. The upper limit is used for dense oxide layers and the lower limit is used for loose oxide layers to quantify the degree of carbon depletion in the oxide layers.

[0046] By using a correction logic that couples the oxide layer ratio with the depletion coefficient, the interference of the surface oxide layer on the LIBS carburizing gradient detection is eliminated. This enables the restoration of the true carbon distribution gradient of the carburized layer, avoids inaccurate austenitizing temperature settings due to measurement deviations, provides accurate compositional distribution basis for subsequent temperature calculations, and ensures the accuracy of carburized layer gradient compensation.

[0047] Based on the material equilibrium austenitizing temperature, three adjustment terms—surface carbon content compensation, carburizing gradient compensation, and residual stress correction—are sequentially superimposed to obtain the theoretically optimal temperature. This optimal temperature is then minimized by the upper temperature limit, ultimately outputting the target heating temperature T for the i-th region. target,i The specific processing logic is as follows:

[0048]

[0049]

[0050] Among them, the basic term T Ae3 The equilibrium austenitizing transformation temperature of the material is the baseline value for calculation; the surface carbon content compensation term α1×C surf,i Linear multiplication is used for calculation. Carbon is the element that expands the austenite phase region. The higher the surface carbon content, the lower the austenitizing temperature. α1 is a pre-calibrated negative coefficient, ranging from -10 to -30. The lower limit of the absolute value is used for high-carbon steel, and the upper limit of the absolute value is used for low-carbon steel. The carburizing gradient compensation term is α2×ΔC. g,i,corr Linear multiplication is used for calculation. The larger the carburized layer gradient, the lower the internal carbon content and the higher the austenitizing temperature. Therefore, a positive compensation is added, with α2 ranging from 5 to 15, taking the upper limit for deep carburizing and the lower limit for shallow carburizing; the residual stress correction term is -α3×σ. res,i The calculation is performed using linear multiplication and the negative sign is taken. The residual tensile stress will reduce the interatomic bonding force and promote austenite nucleation, thus reducing the required austenitizing temperature. The value of α3 is in the range of 0.05-0.2, with the upper limit taken for high manganese steel and the lower limit taken for low alloy steel.

[0051] The upper temperature limit is set using the min function, ensuring that the austenitizing temperature does not exceed T. Ae3 + TAe3_max_offset To avoid excessively high temperatures that could cause rapid austenite grain growth and deteriorate subsequent strength and toughness. Ae3_max_offset The value range is 50-80℃, with the lower limit for low alloy steel and the upper limit for high manganese steel and other materials with high overheat sensitivity.

[0052] Through the above calculations, the optimal heating temperature can be matched for the composition and stress characteristics of different regions, ensuring that the carburized layer fully completes the austenite transformation from the surface to the inside, while avoiding coarse austenite grains caused by excessive temperature. This achieves a precise balance between the sufficiency of austenitization and the control of grain size, and solves the problem of mismatch in the degree of austenitization in different regions.

[0053] Furthermore, the partitioned calculation module also includes a second module. After the first module completes the calculation of the austenitizing target temperature, the second module executes the optimal holding time calculation process. The core logic is to use the basic holding time as a benchmark, superimpose multiple factors such as temperature deviation, carbide dissolution, grain growth, and workpiece thickness correction, and set a lower limit constraint for the holding time to ensure that the carbide is fully dissolved and the composition is homogenized while avoiding excessive grain growth.

[0054] Specifically, firstly, emissivity interference correction is applied to the grain growth accumulation factor during the heating process to eliminate the temperature integration error caused by surface emissivity deviation in the infrared temperature sensor. Before correction, the original grain growth accumulation factor A is first calculated. g,i,raw The processing logic is as follows:

[0055]

[0056] Where t0 is the start time of heating, t1 is the time to reach the target temperature, and T(t) is the real-time temperature collected by the infrared sensor. Ae1 This is the lower limit temperature for the pearlite transformation of the material. Only when the temperature is above T... Ae1 Austenite grain growth only occurs when the temperature reaches a certain threshold. Therefore, the max function is used to set the portion below this temperature to 0, and only the effective temperature deviation is integrated over time to accurately quantify the total contribution of the temperature and time coupling effect to grain growth.

[0057] Subsequently, the actual infrared emissivity ε of the i-th region was calculated based on the surface roughness. act,i The processing logic is as follows:

[0058]

[0059] The higher the surface roughness, the greater the infrared emissivity, and subsequently the accumulation factor A of austenite grain growth in the i-th region. g,i,corr Make corrections:

[0060]

[0061] Where k emis This is the emissivity correction factor, ranging from 0.8 to 1.2. The upper limit is used for long-wave infrared sensors, and the lower limit for short-wave infrared sensors. It quantifies the impact of emissivity deviation on temperature measurement. Actual emissivity is higher than the default value ε. setWhen the temperature measured by the infrared sensor is too low, the original integral value is too small. Therefore, it is multiplied by a coefficient greater than 1 for amplification correction; conversely, it is multiplied by a coefficient less than 1 for reduction correction to restore the true grain growth accumulation.

[0062] The total amount of grain growth during the heating process is quantified by integrating the temperature deviation over time. At the same time, surface emissivity correction is introduced to eliminate infrared temperature measurement errors. This can accurately reflect the degree of grain growth that has occurred during the heating stage, avoid errors in the calculation of grain growth due to temperature measurement deviation, and provide a reliable basis for the dynamic adjustment of the subsequent holding time.

[0063] Specifically, based on the basic heat preservation time, four adjustment items—temperature deviation compensation, carbide dissolution compensation, grain growth correction, and workpiece thickness compensation—are sequentially added to obtain the theoretically optimal heat preservation time. The maximum value of this adjustment is then taken from the theoretically optimal heat preservation time and the lower limit of the time, ultimately outputting the optimal heat preservation time t for the i-th region. hold,i The calculation formula is:

[0064]

[0065]

[0066]

[0067]

[0068] Among them, the basic term t base,i The pre-calibrated basic insulation time for the i-th region is the baseline value for calculation; the temperature deviation compensation term β1×|T target,i -T avg,i The absolute value of the temperature deviation is calculated using linear multiplication. The larger the deviation between the average temperature at the end of the heating period and the target temperature, the slower the rate of carbide dissolution and component diffusion, and the longer the required holding time. β1 ranges from 10 to 30, with the upper limit for high-alloy steel and the lower limit for low-alloy steel; the carbide dissolution compensation term is β2 × Cr. i ×(1+k C ×|C surf,i -C opt |) A product-based composite calculation is used. Chromium is a strong carbide-forming element; the higher the content, the more stable the carbide, the longer the dissolution time, the greater the deviation of the surface carbon content from the optimal value, the worse the dissolution kinetics of the carbide, and the longer the required time. β2 ranges from 50 to 150, with the upper limit taken for high-hardness alloy carbides and the lower limit for ordinary cementite. k C The value ranges from 0.2 to 0.5, with the upper limit for low-temperature diffusion and the lower limit for high-temperature diffusion.

[0069] More specifically, the grain growth correction term -β3×A g,i,corrLinear multiplication is used for calculation, and the negative sign is taken. The greater the cumulative grain growth during the heating process, the smaller the allowable growth space during subsequent holding. Therefore, this correction is subtracted to shorten the holding time and avoid exceeding the total growth limit. The value of β3 ranges from 0.001 to 0.005, with the upper limit for coarse-grained steel and the lower limit for fine-grained steel; the workpiece thickness compensation term is β4×d. eff,i The linear multiplication method is used for calculation. The larger the effective thickness of the workpiece, the longer the time it takes for heat to be transferred to the interior, and the longer the time required for internal temperature homogenization and carbide dissolution. Therefore, a positive compensation amount is superimposed, and the value of β4 ranges from 5 to 15.

[0070] The minimum time constraint is set using the max function, ensuring that the insulation time is not less than t. hold_min_ratio ×t base,i , t hold_min_ratio The pre-calibration is uniformly set to 0.6, which conforms to the general specifications of the heat treatment industry, avoids excessive correction that leads to insufficient holding time, and ensures the most basic carbide dissolution time.

[0071] The above calculations ensure that carbides are fully dissolved and components are uniformly diffused, meeting the requirements for sufficient austenitization. They also allow for dynamic shortening of the holding time based on grain growth during the heating stage, preventing excessive grain growth. Simultaneously, they ensure sufficient insulation within thick regions, achieving synergistic optimization of carbide dissolution and grain size control.

[0072] Furthermore, the partitioned calculation module also includes a third module. After the second module completes the calculation of the optimal holding time, the third module executes the cooling rate calculation process. The core logic is to calculate the basic cooling rate based on the phase change temperature range and the holding time, superimpose the service conditions and thermal resistance correction, and set upper and lower limits for the cooling rate. This ensures that a fully martensitic structure is obtained while avoiding quenching cracks, and also provides early warning for abnormal coating residues.

[0073] Specifically, the thermal resistance of the residual coating is first corrected for porosity interference to eliminate the calculation error caused by porosity differences. Before correction, the residual thermal resistance R of the original coating is first calculated. coat,i,raw The calculation logic is as follows:

[0074]

[0075] Based on Fourier's law of heat conduction, thermal resistance is directly proportional to the coating thickness and inversely proportional to the thermal conductivity, λ. coat The thermal conductivity of the dense refractory coating is taken in the range of 0.1-0.3, with the upper limit for high-alumina coatings and the lower limit for quartz coatings. Subsequently, the residual thermal resistance factor R of the coating in the i-th region is calculated. coat,i,corr Make corrections:

[0076]

[0077] Where k por This is a porosity correction coefficient for the coating, ranging from 2 to 5, with the upper limit for connected pores and the lower limit for closed pores. It quantifies the percentage increase in thermal resistance for every 1% increase in porosity. The thermal conductivity of air in the pores is much lower than that of the coating itself; the higher the porosity, the lower the actual thermal conductivity of the coating and the greater the thermal resistance. Therefore, a linear amplification correction is used to restore the true thermal resistance of the residual coating.

[0078] Next, an anomaly in thermal resistance is assessed. When the corrected thermal resistance R of the coating... coat,i,corr Exceeding the threshold R th When marked as Status B, an error message is immediately triggered: "Residual paint is too thick; it is recommended to clean and retest." th The value range is 0.001-0.005, with the upper limit for high-cooling-capacity equipment and the lower limit for low-cooling-capacity equipment. Excessive residual coating thickness will lead to excessive thermal resistance, making it impossible to achieve the required cooling rate even with adjustments to the cooling medium flow rate; the coating must be cleaned before continuing the process.

[0079] When R coat,i,corr ≤R th When this condition is marked as A, the base cooling rate is obtained by dividing the phase change temperature range by the holding time. Then, three adjustment terms—medium heat transfer correction, service condition correction, and thermal resistance correction—are sequentially added to obtain the theoretical cooling rate. This theoretical rate is then first minimized by the upper limit value, and then maximized by the lower limit value. Finally, the target cooling rate v for the i-th region is output. cool,i The calculation formula is:

[0080]

[0081]

[0082]

[0083] Specifically, the base cooling rate term (T) target,i -T Mf ) / t hold,i The calculation uses division, with the numerator being the total temperature difference in the phase transformation range from the austenitizing temperature to the martensitic transformation termination temperature, and the denominator being the holding time. This yields the average cooling rate required to completely cool this temperature difference within the holding time, representing the minimum requirement for obtaining a fully martensitic microstructure. γ1 is the heat transfer correction coefficient for the cooling medium, ranging from 0.8 to 1.5, with the upper limit for water and the lower limit for oil, to accommodate the differences in heat transfer capacity between different cooling media. The service condition correction term is 1 + γ2 × f. imp,iThe linear addition method is used for calculation. A higher proportion of impact load requires a higher cooling rate to achieve higher hardness and wear resistance. Therefore, a coefficient greater than 1 is used to amplify the cooling rate. γ2 ranges from 0.1 to 0.3, with the upper limit used for high hardness requirements and the lower limit used for high toughness requirements. The thermal resistance correction term is 1 + γ3 × R. coat,i,corr The linear addition method is used for calculation. The greater the residual thermal resistance of the coating, the more difficult the heat transfer is, and the higher the medium cooling rate is required to offset the effect of thermal resistance. The value of γ3 is in the range of 100-300, with the upper limit for strong convection and the lower limit for weak convection.

[0084] More specifically, the theoretical rate is limited to below the critical rate of quenching cracking v by using the min function. upper To prevent excessively high cooling rates from causing internal stresses in the workpiece to exceed its fracture strength and lead to cracking, a max function is used to limit the rate above the critical martensitic transformation rate v. lower To avoid excessively low cooling rates that could cause undercooled austenite to decompose into pearlite or bainite, thus affecting the final performance. upper and v lower All are pre-calibrated according to the specific material grade.

[0085] The calculated target heating temperature T of the i-th region target,i The optimal heat preservation time t for the i-th region hold,i and the target cooling rate v of region i cool,i It is directly mapped to the temperature control parameters, holding time control parameters, and flow control parameters of the heat treatment furnace and the quenching and cooling system, so as to realize the differentiated heat treatment process control of different areas of the hammerhead and improve the overall service life and reliability of the hammerhead.

[0086] By using thermal resistance calculation logic coupled with thickness and porosity, the actual thermal resistance effect of residual coating on the cooling process can be accurately quantified, eliminating the thermal resistance calculation deviation caused by porosity differences. This provides an accurate basis for adjusting the subsequent cooling rate. At the same time, by judging the thermal resistance threshold, abnormal situations of excessive residual coating can be identified in advance, avoiding cooling failure caused by insufficient heat exchange conditions.

[0087] The cooling rate is based on the ratio of the phase transformation temperature zone to the holding time, with double corrections for service conditions and thermal resistance. At the same time, upper and lower limits of the cooling rate are set to ensure that the cooling rate is higher than the critical value of martensitic transformation to obtain the target full martensitic structure, while avoiding the cooling rate from exceeding the quenching crack threshold to reduce the risk of quenching crack. In addition, the cooling rate can be adjusted according to the impact load requirements of different regions to match the different requirements of service conditions for hardness and toughness.

[0088] Through the above processing steps, the control system forms a parameter control logic covering the entire process of austenitization, heat preservation, and cooling. This enables differentiated and customized calculation of heat treatment parameters for each region of the lost foam casting hammerhead, allowing the process parameters to be precisely adapted to the actual casting state, composition characteristics, and service requirements of each hammerhead. This significantly improves the adaptability of the heat treatment process and the consistency of product performance. S3: Zoned Heating: The hammerhead is sent into a zoned temperature-controlled heat treatment furnace. Based on the parameters output by the control system, differentiated heating power control is applied to different regions. During the heating process, temperature sensors monitor the temperature of each region in real time to ensure that the temperature error is controlled within ±5℃.

[0089] S4: Differentiated insulation: After each area reaches the target temperature, the insulation is carried out in zones according to the optimal insulation time output by the system, and surface decarburization is avoided during the insulation process;

[0090] S5: Zone quenching: After the heat preservation is completed, the hammer head is quickly transferred to the zone cooling station and zone quenching is performed according to the target value output by the control system.

[0091] S6: Low-temperature tempering treatment: After quenching, the hammer head is sent into a tempering furnace to eliminate residual quenching stress and obtain a matching structure with high hardness and high toughness.

[0092] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is limited by the appended claims and their equivalents.

Claims

1. A high wear-resistant lost foam casting hammerhead, comprising a mounting section, a striking section, and a transition section, characterized in that: The transition section is located between the mounting section and the striking section, and the hammer head is cast from low alloy steel and high manganese steel.

2. The high wear-resistant lost foam casting hammerhead according to claim 1, characterized in that: First, a 1.5-2.0mm thick coating is applied to the surface of the lost foam model. The coating is then dried at 40-50℃. The dried lost foam model is then combined with the gating and riser model to form a model cluster, which is fixed in a sand box for later use. Subsequently, low-alloy steel and high-manganese steel are placed in a melting furnace for melting. The molten low-alloy steel is first poured into the mold, and then the molten high-manganese steel is poured into the mold. After molding, a heat treatment process is performed to obtain a high-wear-resistant lost foam casting hammerhead.

3. A synergistic heat treatment method for manufacturing the high wear-resistant lost foam casting hammerhead as described in claim 2, characterized in that: Includes the following steps: S1: Post-casting pretreatment: After the lost foam casting of the hammer head is naturally cooled to room temperature, it is shot blasted to remove most of the residual refractory coating and oxide scale, leaving a thin oxide layer of less than 0.5 mm to avoid excessive grinding and damage to the substrate; S2: Parameter pre-calculation: The pre-treated hammerhead is transported to the inspection station, and data is collected synchronously through the integrated multi-sensor array. Then, the control system automatically calculates the austenitizing target temperature, optimal heat preservation time and target cooling rate of each area. At the same time, it automatically identifies abnormal areas with excessive residual coating and outputs cleaning prompts. S3: Zoned heating: The hammerhead is sent into the zoned temperature-controlled heat treatment furnace. Based on the parameters output by the control system, different heating power is controlled for different zones. During the heating process, the temperature of each zone is monitored in real time by temperature sensors to ensure that the temperature error is controlled within ±5℃. S4: Differentiated insulation: After each area reaches the target temperature, the insulation is carried out in zones according to the optimal insulation time output by the system, and surface decarburization is avoided during the insulation process; S5: Zone quenching: After the heat preservation is completed, the hammer head is quickly transferred to the zone cooling station and zone quenching is performed according to the target value output by the control system. S6: Low-temperature tempering treatment: After quenching, the hammer head is sent into a tempering furnace to eliminate residual quenching stress and obtain a matching structure with high hardness and high toughness.

4. The synergistic heat treatment method for high wear-resistant lost foam casting hammerheads according to claim 3, characterized in that: The control system includes an acquisition module, a data preprocessing module, and a zone calculation module. The acquisition module obtains multi-source detection data for each region of the hammerhead and divides the detection data into data related to austenitizing temperature calculation, holding time calculation, and cooling rate calculation. The data is then sent to the data preprocessing module for cleaning and standardization. The processed data is then input into the zone calculation module, which sequentially outputs the target heating temperature of the i-th region, the optimal holding time of the i-th region, and the target cooling rate of the i-th region, thereby achieving differentiated and precise control of the heat treatment process parameters for each region of the hammerhead.

5. The synergistic heat treatment method for high wear-resistant lost foam casting hammerheads according to claim 4, characterized in that: The partition calculation module includes a first module, a second module, and a third module.

6. The synergistic heat treatment method for high wear-resistant lost foam casting hammerheads according to claim 5, characterized in that: The processing logic of the first section is as follows: First, the measured original carburized layer gradient difference is corrected for oxidation interference to eliminate the measurement error caused by the depletion of the surface oxide layer. Then, based on the material equilibrium austenitizing temperature, three adjustment items are added in sequence: surface carbon content compensation, carburizing gradient compensation, and residual stress correction. After obtaining the theoretical optimal temperature, the minimum value is taken from the upper limit of the temperature, and finally the target heating temperature of the i-th region is output.

7. The synergistic heat treatment method for high wear-resistant lost foam casting hammerheads according to claim 6, characterized in that: The processing logic of the second section is as follows: First, the emissivity interference correction is applied to the grain growth accumulation factor during the heating process to eliminate the temperature integration error caused by the surface emissivity deviation of the infrared temperature sensor. Then, the actual infrared emissivity of the i-th region is calculated based on the surface roughness. Finally, based on the basic heat preservation time, four adjustment items are added in sequence: temperature deviation compensation, carbide dissolution compensation, grain growth correction, and workpiece thickness compensation. After obtaining the theoretical optimal heat preservation time, the maximum value is taken from the lower limit of the time, and the optimal heat preservation time of the i-th region is finally output.

8. The synergistic heat treatment method for high wear-resistant lost foam casting hammerheads according to claim 7, characterized in that: The processing logic of the third section is as follows: First, the residual thermal resistance of the original coating is calculated. Then, the thermal resistance of the residual coating is corrected for porosity interference to eliminate the thermal resistance calculation error caused by porosity differences, so as to obtain the residual thermal resistance factor of the coating in the i-th region and restore the true thermal resistance of the residual coating. Next, the thermal resistance anomaly judgment is performed, and the target cooling rate of the i-th region is determined through the anomaly judgment.

9. The synergistic heat treatment method for high wear-resistant lost foam casting hammerheads according to claim 8, characterized in that: The processing logic for determining thermal resistance anomalies is as follows: When the residual thermal resistance factor of the coating in region i exceeds the threshold, it is marked as condition B, and an abnormal prompt is triggered directly: "The residual coating is too thick. It is recommended to clean it and retest." When the residual thermal resistance factor of the coating in region i does not exceed the threshold, it is marked as condition A. At this time, the basic cooling rate is obtained by dividing the phase change temperature range by the heat preservation time. Then, three adjustment items, namely medium heat transfer correction, service condition correction, and thermal resistance correction, are added in sequence to obtain the theoretical cooling rate. The minimum value is first taken with the upper limit value, and then the maximum value is taken with the lower limit value. Finally, the target cooling rate of region i is output.

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