Dressing method of diamond grinding wheel
The use of a diamond grinding wheel of the CNC tool grinder directly affects the normal use of CNC tools, a small part sometimes may cause the failure of the whole project. So today, we introduce the automatic dressing and compensation method of the diamond grinding wheel of the CNC tool grinder.
The development of fully automatic CNC grinding technology puts forward high requirements for its supporting equipment. As one of the supporting technologies, the online automatic grinding wheel dressing technology must meet the needs of modern CNC grinding technology and develop towards the direction of high precision, super stability, and fully automatic control. A diamond grinding wheel is widely used as an efficient grinding tool in the processing of hard alloy, ceramics, CBN and other superhard materials. The dressing and automatic compensation method of the diamond grinding wheel determine the performance of the fully automatic NC grinding machine. And to a large extent determines the service performance and service life of the grinding wheel.
Principle of diamond grinding wheel dressing
The dressing method of the diamond grinding wheel is an important factor affecting the grinding performance of the grinding wheel. The reasonable selection of dressing method will directly affect the surface quality and grinding accuracy of the workpiece. At present, common dressing methods of the diamond grinding wheel include online electrolytic dressing. EDM grinding wheel dressing, cup-shaped grinding wheel dressing, electrolyte-mechanical dressing, and laser dressing. Since the dressing method of the cup grinding wheel is simpler and easier to realize than other dressing methods, GC cup grinding wheel dressing technology is adopted in this paper to automatically dressing the diamond grinding wheel.
The dressing of a diamond grinding wheel is usually divided into two stages: shaping and sharpening. The purpose of shaping is to remove the shape error and surface defect of the grinding wheel after the initial installation. So as to ensure the geometric precision of the grinding wheel. Sharpening is caused by the passivation of the grinding wheel after working for a period of time. In order to make the cutting micro-edge highlight the binder and have an appropriate height, form enough chip space between the grinding grains and make the effective number of grinding grains per unit area as much as possible.
GC cup grinding wheel dressing method of bowl diamond grinding wheel
During the actual dressing, the bowl-shaped diamond grinding wheel and the grinding belt of the GC cup grinding wheel are completely staggered and fitted and rotate at a certain speed respectively. The rotational linear speed ratio of the dressing wheel and the grinding wheel is located at 8:1. The dressing wheel is fixed, and the diamond grinding wheel is fed with dressing along the axis so that the GC cup grinding wheel and the bowl diamond grinding wheel can form mutual abrasive grinding. By grinding the end face of the two grinding wheels, the diamond grinding wheel passivation grinding particles are removed. The chip space is formed, the diamond grinding wheel surface is re-sharpened, and the purpose of dressing is achieved.
Grinding wheel dressing automatic control method
In the grinding process, the wear state of the grinding wheel is an important factor that affects grinding quality. The CNC tool grinder can monitor the state of the grinding wheel in the whole process of blade grinding. Depending on the size and material of the machined blade, the required grinding removal volume and grinding time are also different. Comprehensive consideration of each factor set automatic dressing interval. The number of times the grinding blade is counted and compared with the dressing interval set by the system in real-time. When the grinding number reaches the set number of dressing intervals, the dressing module is automatically invoked in the NC program to realize the automatic dressing of the grinding wheel. In order to ensure the safe operation of the machine tool, the control method also includes real-time monitoring of the life of the grinding wheel and dressing wheel. As long as it is detected that the dressing may cause the grinding wheel or dressing wheel to reach the pre-warning thickness. The machine will automatically send an alarm signal and stop the machine for manual processing. If the grinding wheel and dressing wheel do not reach the alarm thickness, the dressing will proceed smoothly. After finishing dressing, the compensation value of the grinding wheel after the dressing is output through data processing.
Compensation method for grinding wheel dressing
The consistency of the workpiece size is largely dependent on the consistency of the process system state. After dressing the grinding wheel once, the abrasive thickness decreases and the end face of the grinding wheel changes to the designated calibration position. This will lead to the change of the state of the entire process system and the size of the workpiece being processed will also change, so the size consistency cannot be guaranteed. Therefore, the compensation after grinding wheel dressing is particularly important.
The process of dressing the grinding wheel is analyzed, which is the mutual grinding of two grinding tools. Not only will the abrasive thickness of the grinding wheel decrease, but also the abrasive thickness of the dressing wheel decrease, which is a result of comprehensive action. Therefore, the method of multiple tests is adopted to determine the compensation method of grinding wheel dressing.
The hardness and abrasion resistance of the diamond grinding wheel is much higher than that of the GC cup dressing wheel. It can be predicted that in a dressing process, the abrasive thickness reduced by the diamond grinding wheel is far less than that reduced by the dressing wheel. The dressing wheel is in a fixed position. During dressing, the grinding wheel advances one dressing amount along the feed direction. The relationship between them is dressing amount = reduction of grinding wheel dressing wheel reduction. In order to ensure the size consistency of the processed workpiece, the reduction of the grinding wheel after dressing should be compensated. The actual dressing test data show that when the dressing amount is 0.03mm, the thinning amount of the grinding wheel is 0.0015mm and that of dressing wheel is 0.0275mm.
