Application of CNC flame cutting in the world's largest reducer bearing housing

As the leading heavy machinery manufacturer in the country, CITIC Heavy Industry Machinery Co., Ltd. supplies a wide range of heavy equipment to clients around the globe. One of the key components is a massive speed reducer, manufactured by a foreign company (as shown in Figure 1). This gear box is **welded** and stands at an impressive height of 7.1 meters, with a length of 7 meters, a width of 5.72 meters, and a total weight of 320 tons. It is recognized as the world’s largest gearbox for a reducer. The housing is made from S355JR steel, with a thickness of 320mm, making it a challenging component to cut and process. To handle this complex task, the company utilized its existing special thick plate CNC flame cutting machine. By carefully selecting the right cutting parameters, the team successfully completed the CNC cutting operation, demonstrating their technical expertise and precision.


Reducer

**1. Introduction of Equipment and Parts** The cutting was performed using a CNC flame cutting machine produced by Messer Cutting & **Welding** (China) Co., Ltd. This machine is capable of cutting black metals up to 600mm thick, with a gauge length of 6000mm and a rail length of 20,000mm. The gas used for the process is a mixture of oxygen and propane. The specific model used for this job is illustrated in Figure 2.


Extra Thick Plate CNC Cutting Machine

The part being cut is a bearing housing, measuring 320mm x 1310mm x (5790 + 8) mm. The material is S355JR, a low-alloy high-strength steel commonly used in European standards (EN10025), with a yield strength of 355MPa—equivalent to domestic Q345B. The extra 8mm in length is reserved for **welding** shrinkage. A photo of the raw workpiece is shown in Figure 3.


Workpiece Blank

**2. Preparation Before Cutting** Before starting the cutting process, the steel plate underwent ultrasonic inspection according to the EN10160-1999 standard. The body defect level was set to S3, while the edge defect level was E4. This ensured that the material met the required quality standards before processing. First, we checked the gas pipelines for leaks. Any air leakage could not only waste resources but also affect the cutting quality. In extreme cases, it could lead to dangerous gas accumulation and even explosions. Therefore, this step was crucial for both safety and efficiency. Next, we calibrated the cutting machine's accuracy. Since flame cutting is a thermal process, various factors during the operation can influence the precision of the cut. To ensure reliable results, we conducted a test by drawing a rectangle parallel to the guide rail on a full steel plate and programming the torch to follow the same path. We then observed any deviation between the actual path and the drawn shape. If the deviation exceeded acceptable limits, the **machine tool** was repaired by professionals until the specifications were met. Finally, we checked the flatness of the cutting platform. Adjustments were made to ensure the support plates were evenly spaced and fully in contact with the workpiece, preventing any deformation or instability during the process. **3. Cutting Process** During the cutting operation, we selected optimal parameters after several trial cuts. The final settings are detailed in the attached table. Given the winter conditions, we implemented a two-cut method to prevent cracking caused by rapid cooling. The first cut was made along the outer contour of the blank, adding 30mm to the original size. The blank was then cut twice to minimize stress and avoid warping. To further prevent deformation, we used a “locking” technique. This involved introducing a cutting line that kept the workpiece connected to the steel plate during the process, reducing relative movement. This method proved highly effective, as shown in Figure 4 and Figure 5.

Cutting Real Scene


"Lock"

**4. Conclusion** By leveraging their advanced thick plate CNC flame cutting machine and carefully choosing the right cutting parameters, the team successfully completed the cutting of a 320mm-thick ferrous metal component. This achievement not only demonstrated their technical capability but also provided valuable experience for future projects involving ultra-thick plates. The project marked a significant milestone in their ability to handle large-scale, high-precision cutting tasks.

Truck Winch

Truck winches are robust and versatile tools that have become indispensable for truck owners, especially those involved in off - road driving, heavy - duty towing, and industrial applications. These winches are engineered to handle significant pulling forces, making them capable of extricating trucks from challenging situations and assisting with various heavy - load tasks.

Types of Truck Winches
There are several types of truck winches, each with its own unique characteristics and advantages. Electric Winches are among the most popular choices. They draw power from the truck's electrical system, typically the 12 - volt battery. Electric winches are known for their ease of installation and operation. With a simple connection to the battery and the appropriate mounting, they can be up and running quickly. They offer a wide range of pulling capacities, from relatively modest amounts suitable for smaller trucks to extremely high - powered models capable of handling heavy - duty trucks and large loads. However, they do rely on the battery's charge, and continuous use can drain the battery, so it's important to ensure the truck's electrical system can handle the load.

Hydraulic winches, on the other hand, harness the power of the truck's hydraulic system, often connected to the power steering pump or a dedicated hydraulic pump. These winches are prized for their ability to deliver consistent, high - torque pulling power over extended periods without overheating. They are ideal for heavy - duty applications where large trucks need to pull substantial loads, such as in construction, mining, or forestry. Hydraulic winches can operate continuously as long as the engine is running, providing a reliable source of power for demanding tasks. However, their installation is more complex compared to electric winches, and they require proper maintenance of the hydraulic system.

Manual winches are a more basic option. They are operated by hand, using a crank mechanism. Manual winches are simple in design and relatively inexpensive. They can be a good backup option or suitable for light - duty tasks where the truck is not stuck too firmly or when the load is not overly heavy. But they require significant physical effort from the operator, and the pulling speed is much slower compared to electric or hydraulic winches.

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