Selection of angle grinder bearings
The power of angle grinders is constantly increasing with the requirements of end customers. From the earliest 650W to the current highest 1250W. The increase in power also makes the selection of bearing subdivisions much higher. The bearing model is still represented by the Bosch angle grinder 6-100 angle grinder. Use 607 2RS, 607 ZZ, 608 2RS on the rotor, 606 ZZ, 6201 2RS on the head shell.
At present, the rotor speed of angle grinding is about 35000r/min-45000r/min. Under this high-speed working condition, there are higher requirements for the selection of our Yuanhe transmission bearing configuration. Generally, it is necessary to pay attention to the reasonable selection of bearing sealing form, clearance (radial clearance between steel ball and inner and outer rings), grease, steel ball and cage. Let us first talk about the selection of 607 2RS, 607ZZ and 608 2RS on the rotor of the angle grinder.
Selection of 607 2RS and 607ZZ at the rotor commutator end
Since the 607 2RS and 607ZZ bearings are wrapped in rubber sleeves, the time from rotor stagnation to running is shorter. 607 2RS, 607ZZ need to quickly dissipate the heat generated in the bearing chamber to avoid damage to the retainer, steel ball and other accessories inside the bearing chamber due to excessive temperature. Under this working condition, we will use high temperature and high speed grease (generally represented by Klüber Germany and Japan synergy) in the selection process to avoid the temperature generated during the high-speed operation of the bearing.
When some customers of the complete machine have done a good job of the dustproof structure at the end of the angle grinder, we will try to use the 607 ZZ product when choosing the commutator end bearing. Solving the problem of heat dissipation of the bearing itself has a very obvious effect. The cover of 607 ZZ bearing is iron, generally made of carbon steel. During the high-speed operation of the bearing, the temperature will be dissipated by the heat conduction of the cover, which has a good effect on the heat dissipation of the bearing.
The clearance of 607 2RS and 607ZZ bearings (radial clearance between steel balls and inner and outer rings) should not be too large. The ditch rate of the bearing should not be too large. During the high-speed operation of the rotor, there will be an axial channeling force. 608 2RS bearing will damage the channel and steel ball of 607 2RS and 607Z bearing if the force exists for a long time. There is even a risk of the retainer breaking when the force is too great. Therefore, the selection of clearance and ditch rate must be calculated strictly according to the machining accuracy of the customer of the complete machine.
Selection of rotor blade end bearing 608 2RS
The clearance of the 608 2RS bearing (radial clearance between the steel ball and the inner and outer rings) should not be too large, and the ditch rate of the bearing should not be too large. During the high-speed operation of the rotor, there will be an axial channeling force. Under the action of long-term axial force, the 608 2RS bearing will damage the channel and steel ball of the 608 2RS bearing. Even when the force is too large, there is a risk of the retainer breaking, so the selection of clearance and ditch rate must be strictly calculated according to the machining accuracy of the complete machine customer.
The seal selection of 608 2RS bearings is currently mostly light contact. The rotor blade end and the 608 2RS bearing are in direct contact with the gear box of the angle grinder, and there is grease for the gear in the gear box. During the high-speed operation of the rotor, the rotation speed becomes faster and faster, the grease temperature of the gearbox and the pressure inside the gearbox will also increase, and the state of the grease will also become thinner. The grease of the gearbox will enter the bearing chamber through the groove of the 608 2RS inner ring. When the grease of the gearbox enters the bearing chamber, the life of the bearing will be greatly reduced. Sometimes the grease enters the bearing chamber for 1-2 minutes, and the 608 In the 2RS bearing chamber, there will be damage to the channel, and the retainer will break, causing the bearing to be instantly stuck.
When choosing the rotor end 608 2RS of the fan blade, we must pay attention to the selection of the sealing structure. Sometimes 608 ZZ may not be used at the rotor blade end. If the manufacturer of the whole machine can make a good oil-proof structure to ensure that the 608 2RS bearing and the grease of the gearbox are not in contact, it can be selected.
Woolen material (PA66）
When selecting the 608 2RS bearing in the rotor part of the fan blade, the cage made of woolen material (PA66) should be selected. Because of the high rotational speed of the rotor, the heat generated by the bearing chamber needs to be dissipated. Since this part of 608 2RS is a sealing ring cover, the heat dissipation effect is poorer than that of the iron cover. In this case, we have to find a way to reduce the heat generation inside the bearing chamber. Using the wool retainer, the steel balls will reduce a lot of friction during the operation of the channel, thus reducing the heat generated inside the 608 2RS.
In the selection of angle grinding rotor bearings, Yuanhe Transmission has senior complete machine design experts in the industry as selection consultants, and makes accurate selection based on the working conditions of end customers. In this issue, we will share with you the 607 2RS, 607ZZ, 608 2RS bearings on the angle grinder rotor. In the next issue, we will share the selection of angle grinder head shell bearings, so stay tuned.