The cone ring support plate, a sub-box component of a multi-speed transmission in heavy-duty trucks, plays a critical role despite experiencing relatively low loads during operation. It works in conjunction with other gears to enable gear shifting, and its internal teeth must maintain wear resistance due to friction. Given the precision requirements for mating with other components, the workpiece must undergo strict deformation control during heat treatment. The blank is forged from 40Cr steel, and the production process includes forging, preliminary tempering, machining, internal tooth strengthening, finishing, and final heat treatment. To meet service demands, the internal teeth must achieve a hardness of at least 50HRC, which requires surface strengthening. This paper explores two heat treatment methods—ion nitriding and induction hardening—and compares their economic efficiency to determine the most suitable process.
Ion nitriding is a modern surface modification technique that improves material hardness and wear resistance. Compared to traditional gas nitriding, it offers better layer quality, controllable structure, minimal deformation, and a shorter production cycle. The process involves cleaning the workpiece, loading into the furnace, vacuuming, arcing, heating, holding, and testing. For the cone ring support plate, which has a thin wall thickness (10 mm) and requires internal tooth strengthening, the process parameters are carefully controlled to prevent deformation. The heating rate is gradual, and the temperature is maintained at (500±20)°C for less than 4 hours to avoid coarse nitride structures. Proper furnace loading ensures even heating, with multiple layers stacked and alignment maintained. After ion nitriding, the internal teeth exhibit a surface hardness of 550–600 HV, with a white bright layer of 2–5 μm and a diffusion layer of 0.15–0.25 mm. The roundness deformation of the inner teeth is within 0.05–0.07 mm, meeting the required specifications.
Induction heat treatment is another widely used method for localized strengthening. It provides fast heating, high efficiency, minimal deformation, and excellent surface quality. For the cone ring support plate, a specialized internal tooth quenching sensor was designed, incorporating a "Π"-shaped magnet to enhance heating efficiency. A custom fixture was also developed to reduce quenching deformation. The optimized process parameters include a current of 155A, voltage of 250V, frequency of 23kHz, and a 9-second heating time. After quenching, low-temperature tempering was performed at 180°C for 2 hours. Adjustments were made to the cooling medium concentration and spray pressure, as well as the workpiece design, to minimize deformation. Following these improvements, the hardened layer depth reached 2mm at the tooth root, with a hardness of 52–55HRC, and the deformation of the inner teeth remained under 0.07 mm.
In terms of cost, ion nitriding costs approximately 26 yuan per piece, while induction hardening costs only 4.2 yuan per piece. With an annual output of 30,000 pieces, the cost difference amounts to 654,000 yuan. Therefore, when both technical requirements and deformation control are met, induction hardening is the more economical choice.
This study highlights the importance of selecting the right heat treatment method based on performance and cost, ensuring the cone ring support plate meets all functional and structural requirements.
A moisture meter is a device used to measure the moisture content of materials such as wood, concrete, drywall, and soil. It works by using electrical conductivity to measure the amount of moisture present in the material. The meter typically has two metal probes that are inserted into the material being tested. The display on the meter provides a reading of the moisture content as a percentage. Moisture meters are commonly used in construction, woodworking, and agriculture to ensure that materials are at the appropriate moisture level for their intended use.
Moisture Meter,Digital Moisture Meter,Plant Digital Moisture Meter,Meter Precision Water Analyzer
Lachoi Scientific Instrument (Shaoxing) Co., Ltd. , https://www.lachoinst.com