Characteristics and precautions of diamond roller dressing grinding wheel

2019-08-13 1364

1. Characteristics and applications of diamond rollers

Diamond roller is a newly developed dressing tool. Compared to single particle diamond pen dressing grinding wheels, it has a much shorter dressing time for non linear dressing and is easy to trim various complex formed surfaces. The method of dressing grinding wheels with diamond rollers can be divided into two types: cut-in roller dressing and pendulum roller dressing. As the structure of the cut-in dressing device is simpler than that of the pendulum dressing device, it is more commonly used in actual production. In the cutting in roller dressing, similar to the outer circle cutting in grinding workpiece, the roller is driven by an electric motor to rotate and perform cutting motion relative to the grinding wheel, thereby performing grinding wheel dressing. The main parameters characterizing roller cut in trimming include: trimming speed ratio qd, trimming feed rate, and number of light trimming revolutions. Below is an introduction to the application of the plug-in diamond roller dresser in HSQB885.4 channel grinding.

HSQB885.4 is a large four point contact ball bearing with a peach shaped groove. The existing TM1500 floor grinder is used to replace the vertical grinder to grind the groove, and a TM1500 diamond roller dresser is designed.

The bracket is fixed on the front of the machine tool bed, and the base is installed on the bracket, which can be adjusted in both longitudinal and transverse directions. The roller shaft is a sleeve type spindle, which adopts a two support shaft system structure composed of two sets of angular contact ball bearings. The transmission of the spindle adopts a multi wedge belt transmission, which is stable and reliable. The driving motor is a lightweight aluminum shell wireless speed control motor, and the use of a stepless speed control motor is to ensure that the ratio qd of the linear speed between the roller and the grinding wheel is maintained within a certain range. Due to the consumption of the grinding wheel, its linear speed decreases. At this point, it is necessary to adjust the rotational speed of the roller appropriately to achieve better trimming results. Change the cutting in feed for trimming to grinding wheel feed. During trimming, the roller does not move, and the manual feed mechanism of the original machine tool grinding wheel feed is used to achieve the cutting in motion for trimming.

You can also use the method of grinding wheel not moving and roller feeding for dressing. At this time, the structure of the dressing device is more complex, which uses linear guides, ball screws, stepper motors, etc. The roller dressing action can be designed as a simple CNC system, and its action program is: fast forward (cannot touch the grinding wheel) → slow forward (feed according to the required cutting speed) → light repair → exit.

2. Precautions

Because the diamond roller forming and trimming method has the characteristics of short trimming time, being able to trim various complex surfaces, maintaining good surface accuracy, and convenient trimming operation, its use effect has gradually been recognized by people, and it has also been increasingly widely used in production. However, the following points should be noted in the design, manufacturing, and use of rollers:

The particle size of diamond should be one size coarser than that of the repaired grinding wheel, and the diamond particle size should be selected to be close to the same, with a spherical shape and commonly used particle sizes ranging from 36 # to 100 #.

Usually, the linear velocity direction at the contact point between the roller and the grinding wheel is in the same direction, and the ratio of the linear velocity of the roller to the linear velocity of the grinding wheel (qd value) should be taken as 0.3~ 0.7, which should not exceed 1; When trimming, the cutting amount of the roller is 0.5~1 per revolution of the grinding wheel μ M is appropriate, and the total amount of each grinding wheel trimming should be 0.02-0.04mm; Try to compress the light repair time as much as possible.

The manufacturing error of the diamond roller should be less than about 1/2 of the workpiece tolerance, and the fit gap between the roller hole and the installation bearing should be 2-4 μ M

Natural or artificial diamonds can be used, and artificial diamonds must use high-strength grade diamonds, such as special diamond SCD for steel grinding or high-strength diamond SMD.

When manufacturing rollers, general precision rollers can be manufactured using external plating and sintering methods, while high-precision and complex surface rollers can be manufactured using internal plating method while undergoing grinding and trimming.

When dressing the grinding wheel with a diamond roller, it is necessary to follow the action program of fast forward (not touching the grinding wheel) → slow forward (feeding according to the required cutting speed) → light repair → exit, and do not step wrong, otherwise the service life of the roller will be difficult to guarantee.

The article originates from diamond grinding