High-performance track shoe for trailer and production process
By employing a composite thermal cycle process of medium-frequency induction preheating and high-frequency scanning quenching, the problems of deformation and brittleness of track plates have been solved, enabling the production of high-performance track plates and improving their wear resistance and fatigue life.
Patent Information
- Application Number
- CN202511924180.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-19
- Publication Date
- 2026-04-14
AI Technical Summary
Traditional heat treatment processes for track plates are prone to workpiece deformation or cracking. The quenched layer is shallow and the hardness gradient is uneven, resulting in high brittleness and insufficient wear resistance, making it difficult to maintain high performance under heavy load and impact conditions.
A composite thermal cycle process combining medium-frequency induction preheating and high-frequency scanning quenching is adopted. Through gradient quenching and low-temperature composite quenching, an effective hardened layer with a thickness greater than 2.5 mm is formed. The surface layer is martensite, the subsurface layer is bainite, and the core is sorbite, which avoids high brittleness and improves wear resistance and fatigue strength.
It achieves both high hardness and high toughness of track plates, effectively avoiding deformation and cracking, improving crush resistance and wear life, and increasing bending fatigue life by more than 50%.
Abstract
Description
Technical Field
[0001] This invention relates to the field of trailer track plate manufacturing technology, and in particular to a production process for high-performance track plates for trailers. Background Technology
[0002] Track shoes are the core load-bearing and wear-resistant components of a trailer. Their performance directly determines the overall working efficiency, reliability and service life of the machine. Traditional track shoes are mostly made of medium and high carbon steel or low alloy steel, and their heat treatment process is usually overall quenching combined with low temperature tempering.
[0003] Traditional heat treatment processes involve intense overall quenching and cooling, which can easily lead to workpiece deformation or cracking. This is especially true for track plates with complex structures and large cross-sectional variations, where problems are more likely to occur. Furthermore, the quenched layer is shallow, and although the surface hardness is acceptable, the hardened layer is thin, and the hardness drops sharply from the surface to the core. This makes the track plates prone to deep crushing and spalling under heavy loads and impact conditions. At the same time, in order to ensure the surface hardness of the track plates, the martensite content is high after quenching, resulting in high surface hardness but also high brittleness. If the hardness is reduced to improve toughness, it will lead to insufficient wear resistance. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a high-performance track plate for trailers and a manufacturing process that can ensure the hardness of the track plate while avoiding brittleness, effectively eliminate the risk of workpiece deformation and cracking, achieve deep hardening, and effectively ensure high wear resistance and high fatigue strength.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a manufacturing process for high-performance track plates for trailers, comprising the following sequential steps: First, workpiece pretreatment, firstly providing a track plate blank made of medium carbon alloy steel, which is then rough-machined and stress-relieving annealed; The second step is induction preheating. A medium-frequency induction heating device is used to preheat the entire area of the track plate to be quenched. The preheating temperature is 80-120°C above the temperature at which the medium carbon alloy steel is completely transformed into austenitic structure. The holding time is 60-120 seconds to make the austenitization of the area uniform. The third step is gradient induction hardening, which involves using a high-frequency induction heating device to perform scanning gradient hardening on the workpiece treated with S2. The fourth step is low-temperature composite quenching. The quenched workpiece is placed in a tempering furnace and held at 850-900℃ for 2-4 hours, and then removed from the furnace and air-cooled.
[0006] The specific parameters in the third step are as follows: the heating power is 40-70 kW, which is infinitely adjustable according to the thickness of the track plate cross section; the scanning speed is 250-400 mm / min; the cooling method is controllable spray quenching, the quenching medium is a water-based quenching liquid containing high molecular polymer and corrosion inhibitor, and the pressure is 0.2-0.5MPa; by controlling the matching relationship between the heating power, scanning speed and cooling method, an effective hardened layer with a thickness greater than 2.5mm is formed after quenching, and the surface hardness is HRC42-47.
[0007] The second and third steps can be completed continuously on the same integrated induction hardening machine tool with medium or high frequency switching function. The workpiece is clamped once, avoiding energy damage and oxidation caused by secondary heating.
[0008] The concentration of the polymer in the quenching medium is 8-12%.
[0009] In the third step, the effective hardened layer is defined as a region with a hardness ≥ HRC 38. After quenching, a bainitic region with a smooth hardness transition is formed between the hardened layer and the core, with a width of 0.5-1.0 mm.
[0010] A high-performance track plate for trailers, the base material of which is 40Cr, 42CrMo or medium carbon alloy steel with equivalent properties; its working surface has a fine needle-like martensitic hardened layer with a thickness of 2.5-4.0mm and a surface hardness of HRC44-47; the hardness at a distance of 3mm from its surface is not less than HRC38; the core structure is sorbite or tempered sorbite with a hardness of HRC25-32 and an impact toughness AKU≥100J.
[0011] The present invention has the following beneficial effects: Compared with existing technologies, the high-performance track plates for trailers produced by this invention and their manufacturing process utilize a composite thermal cycle of medium-frequency overall preheating and high-frequency scanning quenching. This process achieves a high-hardness martensite layer on the surface, a tough and resilient bainite layer on the subsurface, and retains tough sorbite in the core, resulting in an ideal microstructure that combines rigidity and flexibility. This avoids the situation where high hardness is accompanied by high brittleness. Furthermore, the continuous preheating and quenching process ensures high thermal energy utilization, minimal workpiece deformation, and effective product consistency. It also allows for a stable effective hardened layer depth of over 2.5 mm, which is 1.5-2 times that of traditional processes. The gradual hardness gradient effectively avoids stress concentration, significantly improving the track plate's crush resistance and wear life. The bending fatigue life of the track plates produced by this invention is more than 50% higher than that of products manufactured using traditional processes. Detailed Implementation
[0012] The present invention will be further described in detail below with reference to specific embodiments: This invention provides a manufacturing process for high-performance track plates for trailers, comprising the following sequential steps: First, workpiece pretreatment, firstly providing a track plate blank made of medium carbon alloy steel, which is then rough-machined and stress-relieving annealed; The second step is induction preheating. A medium-frequency induction heating device is used to preheat the entire area of the track plate to be quenched. The preheating temperature is 80-120°C above the temperature at which the medium carbon alloy steel is completely transformed into austenitic structure. The holding time is 60-120 seconds to make the austenitization of the area uniform. The third step is gradient induction hardening, which involves using a high-frequency induction heating device to perform scanning gradient hardening on the workpiece treated with S2. The fourth step is low-temperature composite quenching. The quenched workpiece is placed in a tempering furnace and held at 850-900℃ for 2-4 hours, and then removed from the furnace and air-cooled.
[0013] The specific parameters in the third step are as follows: the heating power is 40-70 kW, which is infinitely adjustable according to the thickness of the track plate cross section; the scanning speed is 250-400 mm / min; the cooling method is controllable spray quenching, the quenching medium is a water-based quenching liquid containing high molecular polymer and corrosion inhibitor, and the pressure is 0.2-0.5MPa; by controlling the matching relationship between the heating power, scanning speed and cooling method, an effective hardened layer with a thickness greater than 2.5mm is formed after quenching, and the surface hardness is HRC42-47.
[0014] The second and third steps can be completed continuously on the same integrated induction hardening machine tool with medium or high frequency switching function. The workpiece is clamped once, avoiding energy damage and oxidation caused by secondary heating.
[0015] The concentration of the polymer in the quenching medium is 8-12%, which serves to reduce the cooling rate of water at low temperatures, form an ideal quenching curve, and reduce structural stress.
[0016] In the third step, the effective hardened layer is defined as a region with a hardness ≥ HRC 38. After quenching, a bainitic region with a smooth hardness transition is formed between the hardened layer and the core, with a width of 0.5-1.0 mm.
[0017] A high-performance track plate for trailers, the base material of which is 40Cr, 42CrMo or medium carbon alloy steel with equivalent properties; its working surface has a fine needle-like martensitic hardened layer with a thickness of 2.5-4.0mm and a surface hardness of HRC44-47; the hardness at a distance of 3mm from its surface is not less than HRC38; the core structure is sorbite or tempered sorbite with a hardness of HRC25-32 and an impact toughness AKU≥100J.
[0018] Based on the above production process, the process parameters can be selected within a certain range to obtain different properties and hardness.
[0019] Example 1: Material: 42CrMo steel was selected and forged into a track plate blank with a length of 500mm. Step 1: After machining, stress-relief annealing at 550℃ for 3 hours. Step 2: Medium-frequency induction preheating to 900℃, holding for 90 seconds. Step 3: Switching to high frequency, power set at 55kW, scanning speed 300 mm / min, and quenching using a 10% polymer aqueous solution spray. Step 4: Tempering at 870℃ for 3 hours. Production using this method yields a surface hardness of HRC46.5, an effective hardened layer depth of 3.2mm, a hardness of HRC42.1 at 2mm from the surface, and HRC35.0 at 4mm from the surface; a core hardness of HRC28.5, and an impact toughness of AKU=125J; the wear rate is only 65% of that of products produced using traditional processes.
[0020] Example 2: Material: 40Cr steel was selected to verify the effectiveness of this process on low-cost materials; Process adjustments were made: the preheating temperature was reduced to 880℃, the high-frequency power was increased to 65kW to compensate for differences in hardenability, and the scanning speed was reduced to 280 mm / min. Production using this method yielded a surface hardness of HRC 45.0; an effective hardened layer depth of 2.8mm; and a core impact toughness of AKU=110J. These key indicators are still comprehensively superior to those of 42CrMo track plates treated with traditional processes, while reducing costs by approximately 15%.
[0021] In summary, this invention achieves an ideal microstructure that combines high hardness and flexibility through a composite thermal cycle of medium-frequency overall preheating and high-frequency scanning quenching. This results in high-hardness martensite in the surface layer, tough and resilient bainite in the subsurface layer, and well-toughened sorbite in the core. This avoids the situation where high hardness is accompanied by high brittleness. Furthermore, the continuous preheating and quenching process ensures high thermal energy utilization, minimal workpiece deformation, and effective product consistency. It also allows for a stable effective hardened layer depth of over 2.5 mm, which is 1.5-2 times that of traditional processes. The gradual hardness gradient effectively avoids stress concentration, significantly improving the crush resistance and wear life of the track plates. The bending fatigue life of the track plates produced by this invention is more than 50% higher than that of products produced by traditional processes.
Claims
1. A manufacturing process for high-performance track pads for trailers, characterized in that, The following steps are included: First, workpiece pretreatment. A track plate blank made of medium carbon alloy steel is first provided for rough machining and stress-relieving annealing. The second step is induction preheating. A medium-frequency induction heating device is used to preheat the entire area of the track plate to be quenched. The preheating temperature is 80-120°C above the temperature at which the medium carbon alloy steel is completely transformed into austenitic structure. The holding time is 60-120 seconds to make the austenitization of the area uniform. The third step is gradient induction hardening, which involves using a high-frequency induction heating device to perform scanning gradient hardening on the workpiece treated with S2. The fourth step is low-temperature composite quenching. The quenched workpiece is placed in a tempering furnace and held at 850-900℃ for 2-4 hours, and then removed from the furnace and air-cooled.
2. The manufacturing process for a high-performance track pad for a trailer according to claim 1, characterized in that, The specific parameters in the third step are as follows: the heating power is 40-70 kW, which is infinitely adjustable according to the thickness of the track plate cross section; the scanning speed is 250-400 mm / min; the cooling method is controllable spray quenching, the quenching medium is a water-based quenching liquid containing high molecular polymer and corrosion inhibitor, and the pressure is 0.2-0.5MPa; by controlling the matching relationship between the heating power, scanning speed and cooling method, an effective hardened layer with a thickness greater than 2.5mm is formed after quenching, and the surface hardness is HRC42-47.
3. The manufacturing process for a high-performance track pad for a trailer according to claim 2, characterized in that: The second and third steps can be completed continuously on the same integrated induction hardening machine tool with medium or high frequency switching function. The workpiece is clamped once, avoiding energy damage and oxidation caused by secondary heating.
4. The manufacturing process for a high-performance track pad for a trailer according to claim 2, characterized in that: The concentration of the polymer in the quenching medium is 8-12%.
5. The manufacturing process for a high-performance track pad for a trailer according to claim 2, characterized in that: In the third step, the effective hardened layer is defined as a region with a hardness ≥ HRC 38. After quenching, a bainitic region with a smooth hardness transition is formed between the hardened layer and the core, with a width of 0.5-1.0 mm.
6. A high-performance track pad for a trailer, comprising the manufacturing process of a high-performance track pad for a trailer as described in any one of claims 1 to 5, characterized in that: Its base material is 40Cr, 42CrMo or medium carbon alloy steel with equivalent properties; Its working surface has a layer of fine needle-like martensitic hardened layer with a thickness of 2.5-4.0mm and a surface hardness of HRC44-47; the hardness at a distance of 3mm from its surface is not less than HRC38; the core structure is sorbite or tempered sorbite with a hardness of HRC25-32 and an impact toughness of AKU≥100J.