The size of the bucket blade is large, consuming a lot of material. The material requirements are high, making it expensive.
By organically combining products, effectively utilizing the bevel dimensions of the product, and using the machining methods sensibly, the characteristics of flame cutting are met.
This achieves the goal of saving material, ultimately creating favorable conditions for enhancing the competitiveness of the company’s products in the market.
The steel plate at the very front edge of the loader bucket is called the blade. It is the first to dig into soil and gravel during operation.
This plate needs to have strong wear resistance. It’s made from steel grade 22SiMn2, which is quenched at high temperatures, making the material quite costly.
Whoever saves on materials wins the market.
Current Processing Situation
The ZL50C loader bucket is shown in Figure 1.
One of its blades has dimensions of 2910mm×290mm×40mm. The cross-sectional view is shown in Figure 2.
The traditional processing method cuts the material according to the blade dimensions of 2910mm×290mm×40mm, followed by flame cutting of the bevel.
The process is simple, but the bevel material weighs up to 1442kg, leading to a waste of up to 11,536 Yuan, representing a significant wastage of material.
Process Improvement Experiment
To save materials, we considered using one flame-cut bevel to obtain two blades, as shown in Figure 3. However, the results were unexpected.
The flame-cut blade edge was uneven, requiring us to use a gantry planer to level the blade’s sloped surface.
The processing was cumbersome, and each blade’s 290mm width could not be guaranteed. The experiment failed.
Cause Analysis
The reasons for the uneven blade edge are mainly:
- During flame cutting, the cutting torch forms a 30° angle with the 2910mm×550.75mm blade surface at the calculated bevel position. At this time, the flame is tilted and cannot focus.
- Along the entire 2910mm long bevel line, the amount of metal melted varies at each point due to the inconsistent time it takes for the gas flame to heat the metal to its ignition point during the cutting process.
- The amount of slag blown away by the high-pressure oxygen stream is also inconsistent.
Comparing the flame cutting of one blade to that of two blades, as shown in Figure 4, it’s evident that due to different product bevel angles, a single blade has a smaller slope and focused flame, whereas two blades have a steeper slope, making it hard to focus the flame.
Solution Determined
The crux of the problem lies in the inability to focus the flame. So, how can the flame be concentrated?
Initially, the solution that came to mind was how to block the flame, essentially using a blocking method.
1. Surfacing weld. Performing a surfacing weld along the entire 2910m bevel line, followed by flame cutting the bevel to form a 90° angle, would allow the flame to concentrate, as shown in Figure 5. However, surfacing welding increases costs.
2. Welding a 2910mm×8mm×8mm strip onto the long bevel line, then flame cutting the bevel, as depicted in Figure 6. There was a challenge when processing the 2910mm×8mm×8mm strip. Ensuring the flatness and straightness of such a long, thin strip is considerably difficult. If purchased externally and then welded, the costs are also quite high.
It seems that the blocking method increases costs and has lower efficiency.
Considering that during the cutting and separation process of the two blades, a gap would form in the direction of the bevel width, where the flame can concentrate, we adopted a method of first machining the gap, then flame cutting to separate the blades.
(1) First, air-planing the gap, then flame cutting the bevel, as shown in Figure 7. After testing, the quality of the flame-cut bevel surface was good, but the air-planed bevel surface was uneven. The straightness of the air-planed line was also subpar, requiring manual grinding for smoothness. This method had higher costs and lower efficiency.
(2) First, gantry planing the gap, then flame cutting the bevel, as depicted in Figure 8. The results were promising.
Therefore, the process for cutting one blade into two was established as: stock removal → gantry planing of the gap → flame cutting of the bevel.
Conclusion
It’s evident that the approach of first gantry planing the gap and then flame cutting the bevel has advantages.
When manufacturing the blade using this method, two processes are added: planing the gap and flame cutting the bevel.
This increases the manufacturing cost by about 40 Yuan, adding about 20 Yuan to each blade’s cost.
Thus, using this method to process a single blade can save 86.55 Yuan compared to the traditional method. If the annual production of this blade is 300,000 pieces, then it can save the company approximately 25.965 million Yuan in material costs throughout the year.
However, the premise is that the company should have a gantry planer or gantry milling machine capable of processing near 3000mm in length.
Otherwise, outsourcing would be required, leading to increased transportation costs and potentially impacting the production plan.
Therefore, the other three methods mentioned can also be considered based on actual circumstances.
