The micro convexity formed by ultra precision grinding of tapered rollers can effectively improve the force distribution of the rollers in bearings, reduce or eliminate stress concentration at the edges of the rollers, reduce temperature rise, and the cross mesh on their surfaces is conducive to forming elastic fluid lubrication, thereby reducing bearing noise and improving bearing life. The technology and equipment for ultra precision machining of tapered roller convexity will directly affect the quality of bearings and are related to the matching work of main engines such as railway passenger cars and sedans. Therefore, the research on ultra precision machining of tapered roller convexity is still a cutting-edge topic in China's bearing industry.
1. Ultra precision research speed
In the process of through type roller convexity ultra precision grinding, the main process parameters that affect the roller ultra precision effect include: ultra precision guide roller speed, ultra oil stone oscillation frequency and amplitude, oil stone model, oil stone pressure, and cooling lubrication. The ultra precision grinding speed (including guide roller speed and oil stone oscillation frequency) has a significant impact on the ultra precision effect and production efficiency, determining the convexity, surface roughness, waviness, and roundness of the tapered roller after ultra precision grinding. Therefore, how to conveniently and effectively control the speed of the guide roller motor and the speed of the oil stone oscillation motor, and obtain suitable guide roller speed and oil stone oscillation frequency, is actually the key technology to complete the ultra precision machining of tapered roller convexity.
Traditionally, domestic ultra precision grinding machines have mostly used thyristor DC speed control devices to achieve control over the speed of ultra precision grinding. Due to the complexity of control circuits, high failure rates, and high maintenance costs, it cannot meet the needs of factory automation production. Luoyang Bearing Research Institute has absorbed advanced experience in foreign bearing equipment and applied advanced variable frequency speed regulation technology on the newly developed 3MZ6130 tapered roller convexity ultra precision grinding machine. The rotation of the guide roller and the oscillation of the oil stone are controlled by a variable frequency speed controller, achieving stepless adjustment and high efficiency and reliability.
2. Principle of variable frequency speed regulation
The speed formula for asynchronous motors is
In the formula, n represents the motor speed
P - Polar logarithm
F - Stator power supply frequency
S - slip rate
As can be seen from the above equation, if the stator power supply frequency f of the motor is uniformly changed, the synchronous speed of the motor can be smoothly changed. At present, using frequency converters to change the input power frequency of AC motors and achieve stepless speed control of AC motors is an efficient speed regulation method. Its performance is superior to previous methods such as variable pole speed regulation, voltage regulation, cascade speed regulation, and slip motor speed regulation. It has gradually replaced DC speed regulation systems in industrialized countries.
3. Variable frequency speed control
The 3MZ6130 taper roller convexity ultra precision grinding machine uses two imported FR-A044 series frequency converters to control the oil stone oscillation motor and the guide roller motor respectively. Figure 1 is a schematic diagram of the variable frequency speed control circuit of the oil stone oscillation motor.
The input terminals R, S, and T of the main circuit of the frequency converter in the figure are connected to a three-phase AC input power supply of 380V, 50Hz, and the output terminals U, V, and W are connected to an oil stone oscillating motor. The wiring of input and output terminals must not be reversed, and the frequency converter and motor must be reliably grounded separately. The frequency setting potentiometer (2W, 1k Ω) is connected to the shielded signal line at terminals 10, 2, and 5 of the frequency converter input control circuit to achieve analog signal input control. The output control circuit of the frequency converter is connected to the FM and SD terminals of the frequency meter monitoring instrument.
Simply adjust the frequency setting potentiometer installed on the machine tool operation panel to easily convert the input power frequency 50Hz to 0-60Hz, achieving AC variable frequency stepless speed control of the oil stone oscillation motor. Through the machine tool oscillation mechanism, the appropriate oil stone oscillation frequency and amplitude can be obtained. It is also possible to directly set the frequency using parameter unit FR-PU03 to achieve digital signal input control. The oscillation frequency of the oil stone is monitored and displayed by instruments or parameter units.
Similarly, using another frequency converter can achieve AC variable frequency stepless speed control of the guide roller motor. After passing through the deceleration device of the machine tool, the appropriate guide roller speed can be obtained. The entire frequency conversion control system is stable and reliable, and can accurately and efficiently ensure the requirements of ultra precision machining of tapered roller convexity.
The 3MZ6130 taper roller convexity ultra precision grinding machine adopts frequency conversion speed control, which has the characteristics of wide speed range, good dynamic response, high speed accuracy, etc. Moreover, due to its complete functions, easy operation, stable and reliable operation, it is convenient for factory automation production. It has gradually become an important equipment for domestic taper roller manufacturers to improve the quality of roller final processing, and has been applied in many bearing enterprises such as Northwest Bearing Factory.
2024 August 5th Week WBM Product Recommendation:
Cutter:
WBM produces taper roller dies with high efficiency and automation. Rollers are formed on a single automatic cold heading press and are fed, cut, and punched into the die for five steps.
We can produce different types and sizes taper roller dies with quality assurance,include:Combination Punch,Outside Sleeve,Blade,Combination Punch,Feed Cylinder,Combination Dies,Double Layer Sleeve,Insert.
