Abstract: In this paper, the author concluded some good practices of extending the service life of high-speed bearing from experience.

Key words: Bearing; Service life

Woodwork processing equipment usually requires a higher rotational speed and a larger cutting amount. For example, the rotational speed of the vertical shaft router is 10000r/min, and the rotational speed of the grooving machine can reach 15 000r/min. For such a high speed machine tool, even the imported bearings lubricated with grease are worn very quickly. If one and a half shifts per day is used, the continuous operation will not exceed one month. The fastest one is to be replaced only a few days because of serious wear. Sometimes the damaged bearing is stuck on the shaft and slips, which makes the shaft and sleeve matched with it worn. Frequent shutdown maintenance and bearing replacement increase production costs and affect production efficiency. In view of this situation, the shaft and shaft sleeve components of the vertical shaft milling machine and the grooving machine are improved, as shown in Figure 1 (the left end of the "vertical shaft router" in the figure is upward, and the left end of the "grooving machine" is downward). The improvement is carried out in four aspects:

1) Double bearings at both ends

Before the improvement (Fig. 1a), both ends of the spindle are supported by a single bearing. After the improvement (Fig. 1b), both ends are supported by a pair of bearings, so that the spindle has greater supporting force and stability when the machine tool runs at high speed. The fitting tolerance of shaft and bearing is js6, which is easy to assemble and disassemble. The thermal expansion generated at high speed can keep the required accuracy of shaft and bearing. The right end bearing is also clamped with nuts, and the sleeve is also turned back. The cutting end is one bearing position deeper than the normal turning. The power end not only needs to be turned one bearing position deeper, but also about 30 mm deeper. The matching tolerance between the hole diameter and the bearing outer ring is G6, and the bearing outer ring can slide in the hole.

2) Add a spring sleeve to the end face of the right end bearing to compress

Press the end face of the outer ring of the right bearing with the spring sleeve (7, 8, 9 in Fig. 1b) (the spring force does not need to be large), and the axial clearance of the bearing can be automatically adjusted. Since the outer ring cannot rotate, the thermal expansion of the shaft at high speed can be extended to the spring direction.

1.Spindle; 2. Upper nut; 3. Upper gland; 4. Sealed bearing or dust-proof bearing; 5, 10. Ring washer; 6. Sleeve; 7. Retaining ring; 8. Spring; 9. Pressing sleeve; 11. Lower gland; 12.Lower nut

Fig. 1 Axle and axlebox before and after modification

3) Modified grease

Open the two covers of a new sealed bearing or a bearing with a dust-proof cover, remove the grease in the bearing, mix it with a thicker grease and more than 20% of the engine anti-wear agent, add it to the bearing (the amount of high-speed bearing should not be more than 60%~70% of the gap, so as not to affect the heat dissipation), and then seal the two covers. The improved grease has the advantages of wear resistance, low temperature rise and low noise, and the service life of the improved bearing can be extended by 4-5 times. When the bearing is worn, the grease in the bearing is usually not completely dried up. This method is also applicable to domestic bearings and ordinary grease, and its effect is not much different.

4) Repair and reuse of worn bearings

The worn sealed bearing or bearing with dust cover can be repaired and reused if the steel ball cage has not been damaged. The specific method is: open the two covers of the bearing, clean the bearing, add improved grease, seal the two covers, and install an annular pad (5 and 10 in Fig. 1b) cut from aluminum foil cans between the outer rings of each pair of bearings to offset the axial clearance of worn bearings, so that the bearings can be used again and new bearings can be saved. If the bearing is worn again, it can be added with improved grease and an additional ring gasket as described above. After test run, if the noise is small and within the allowable range of accuracy, it can be used continuously.

It should be noted that if there are no special requirements for high-speed shafts, open ball bearings and centripetal thrust ball bearings are generally not used to avoid rapid burning of bearings due to splashing of grease.

More about SUNSPEED Rolling Bearings:

Rolling bearings support and guide rotating or oscillating machine elements such as shafts, axles or wheels and transfer loads between machine components. They provide high precision and low friction and therefore enable high rotational speeds while reducing noise, heat, energy consumption and wear. Rolling bearings are cost-effective and exchangeable machine elements that typically follow national or international dimension standards.

Roller bearings also known as rolling-element bearings are similar to ball bearings in that they are designed to carry a load while minimizing friction. However, roller bearings transmit loads using cylinder rolling elements, rather than balls, to maintain the separation between moving parts of the bearing. These versatile bearings can contain single or multiple rows of rolling elements; multiple rows can significantly improve radial load capacity. Also, the use of different roller shapes can further reduce friction and support both radial and axial loads.

SUNSPEED formerly known as Seven Color Bearing co., Ltd. set up in 1996, is a large bearing enterprise in China. The company focuses on 10 categories of bearing products with a total of more than 5000 types. The products are as follows: deep groove ball bearing, tapered roller bearing, self-aligning ball bearing, spherical roller bearing, cylindrical roller bearing, angular contact bearing, thrust ball bearing, thrust roller bearing, needle roller bearing, joint bearing, etc. Bearings are widely used in motor, machine tool, automobile, wind power, mining and other fields.

The company’s private brand “LSCB” is China’s most promising brand, and we always adhere to the principle of “quality first, service first”. The company has established a set of complete sales network and after-service support system, and products are sold both in China and abroad. In order to realize the long-term sustainable development of the company, all SUNSPEED people will keep adhering to the people-oriented concept as well as the principle of “quality first, service first”, sparing no effort in achieving the long-term development of the company.

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