Nordberg GP100 Mainshaft Break Cause Analysis And Countermeasures

Our customer had purchased Nordberg GP100EF cone crusher 2 years ago. In the 2 years running time, the Nordberg GP100 Mainshaft breaks three times. Our customer asks us to help them solve this problem. The following picture is the break areas.

Nordberg GP100 Mainshaft break areas

Nordberg GP100 Mainshaft break areas

Due to frequently broken shafts, not only the normal production is affected, but also the daily maintenance and overhaul work is aggravated, resulting in high maintenance costs. In response to the fault, the cause of the broken shaft was found through analysis and improved, and good results were obtained. The following is a detailed analysis of the improvement.

Nordberg GP100 Mainshaft Structural Analysis

This Nordberg GP100 cone crusher structure like figure 2, the Nordberg GP100 Mainshaft (4)  install into the Mainframe(6); Eccentric bushing(5)  installs into Mainshaft (4); Crushing Cone (2) installs into Eccentric Bushing (5);At the same time, the lower spherical surface of the crushing cone is supported above the spherical bearing liner (3), and the upper end of the Mainshaft (4) is fixed by the Top Bearing (1). The safety device and the adjustment locking device of the crusher are hydraulic, and the lubrication system is basically the same as the ordinary cone crusher.

Nordberg GP100 Mainshaft Structural Analysis

Nordberg GP100 Mainshaft Structural Analysis

  1. Top Bearing
  2. Crushing Cone
  3. Bearing Liner
  4. Mainshaft
  5. Eccentric Bushing
  6. Mainframe

 

 

 

 

 

The crushing process is completed between the fixed cone and the eccentric rotating moving cone. The horizontal axis of the crusher is driven by the motor through the triangular belt. The horizontal shaft drives the eccentric bushing through the gear. When the eccentric bushing rotates, the spindle rotates. An eccentricity is generated to cause the crushing cone to rotate for the crushing motion. The feed enters the crusher through the feed port at the upper part of the crusher, and the crushed stone is discharged through the discharge port at the lower part of the crusher.

Nordberg GP100 Mainshaft Break Reasons Analysis

In just over 2 years of operation, the number of consecutive broken shafts was as many as 3 times. After the first two broken shafts were operated for more than one year, the second time after the replacement of the spindle and the body was only 3 months, it appeared again. Broken shaft failure, from which it can be judged, there must be its inherent reasons.
After careful analysis and research on the fracture of the main shaft, it is considered that the possibility of the main shaft breaking due to quality is almost non-existent. After eliminating the quality problem, the external influence factors, such as the feeding device, the feeding amount, the distribution of the material in the crushing chamber, etc., were searched and analyzed. Finally, the crux is finally found, that is, because the feedstock is biased to one side (Fig. 3), the material is unevenly distributed in the crushing chamber, resulting in uneven load at the bottom of the crushing chamber, thereby generating an impact load, and the spindle is in the process of eccentric rotation. Periodically subjected to the impact force P (Fig. 4), the spindle is repeatedly folded, and finally the spindle fatigue fracture.

Figure 3

    Figure 3
Figure 4

Figure 4

 

 

 

 

 

 

 

 

 

 

 

According to the requirements, the crusher must be equipped with a guiding device to ensure the same load at the bottom of the entire crushing chamber, so that the load can be even, the bearing is well lubricated, and the liner is evenly worn. This can be achieved by adjusting the conveyor, feed chute or baffle. When the crusher is installed, a baffle is arranged in the feeding funnel to ensure the uniform distribution of the material in the crushing chamber. However, during the operation after the production, due to insufficient feeding height and wet materials, the material is Blockage in the feed funnel resulted in poor feed. Since the crushing section of the workshop did not inform the relevant departments to take corresponding measures, the baffle was cut off by itself, causing the feedstock to be biased and uneven load, resulting in frequently broken shafts.

Improvement Measures

Based on the above reasons, we have taken the following measures: Re-recover the baffle in the feed funnel, adjust the height of the free fall of the material to 1.3 m, and adjust the upper frame beam parallel to the feeding direction, while keeping the crusher as much as possible. Packing the feed (filling the feed allows the crusher to maximize its productivity). Through the improvement of these measures, the materials are evenly distributed around the crushing chamber, which greatly improves the stress state of the main shaft, and the working environment and equipment operating conditions are significantly improved.

 

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