Grinding wheel arc dressing device

Ma Shujun

(Qizhong CNC Equipment Co., Ltd.)

For grinders, the grinding wheel dresser is an essential accessory. There are many forms of grinding wheel dressing. Common ones include diamond roller forming dressing and diamond pen dressing. Among them, diamond roller dressing is mostly used on special grinders. Diamond pen dressing is the most widely used. It can be linked with the machine tool CNC axis program to dress the grinding wheel into the required shape. For parallel grinding wheels, the diamond pen required for straight-line trimming of the outer circular generatrix is ​​the simplest. Just fix the diamond pen and let the grinding wheel run in a straight line.

If you want to trim the outer circle generatrix of the grinding wheel into an arc, the effect of using a fixed diamond pen is not very good. In response to this situation, a grinding wheel arc dressing device driven by a servo motor was designed. Through actual verification, it achieved very good dressing effects and was widely used in products.

1.Principle

The diamond dresser is mounted on an extendable sleeve installed at the center of an arcuate dressing arm. Shafts at both ends of the arm connect to supports through bearings. A large timing-belt pulley on one shaft is connected by a timing belt to a small pulley on the gearbox shaft, with a servo motor installed behind the gearbox. A power-off electromagnetic brake is also fitted to the shaft on the same side. A disc spring at the opposite shaft end presses against a friction plate, providing damping for the dressing arm and making its motion smoother.

2.Structure composition

The grinding wheel arc dressing device is shown in Figure 1.

Figure1 Grinding wheel arc dressing device

1. Base; 2. Dressing arm; 3, 18. Seal ring + gasket; 4. Left flange; 5. Gasket; 6. Gasket + locating block; 7. End cover; 8. Friction plate; 9. Disc spring; 10. Left shaft; 11, 22, 25. Locknut; 12, 13, 20, 21, 49. Bush; 14, 15, 26, 42. Bearing; 16. Upper left cover; 17. Upper right cover; 19. Limit switch; 23. Cam; 24. Large timing-belt pulley; 27. Right shaft; 28. Electromagnetic power-off brake; 29. Eccentric flange; 30. Timing belt; 31. Right guard; 32. Motor; 33. Reducer; 34. Clamping flange; 35. Rear cover; 36. Locking assembly; 37. Small timing-belt pulley; 38, 51. Diamond dresser; 39. Sleeve; 40. Screw; 41. Nut; 43. Flange plate; 44. Graduated dial; 45. Knob; 46, 53. Set screw; 47. Coil spring; 48. Pin; 50. Locating sleeve; 52. Flanged seat; 54. Key.

The device is built on a cast Y-shaped base 1. Axial bearings 14, radial bearings 15, sleeves 20, and sealing rings 3 and 18 are installed at the upper left and right ends to support the left and right shafts 10 and 27. Locknuts 11 and 22 on the shafts allow adjustment of the radial clearance of the tapered-bore cylindrical roller bearings 15 and sleeves 20. A friction plate 8 is fitted at the left shaft end. A disc spring 9 holds pad 6 against friction plate 8 and maintains a constant contact force, forming the device's damping mechanism. The disc-spring force can be adjusted through end cover 7.

Dressing arm 2 is connected to shafts 10 and 27 and supported on bearings. A large timing pulley 24 and an electromagnetic power-off brake 28 are mounted on right-hand shaft 27. Timing belt 30 connects large timing pulley 24 to small timing pulley 37. Small timing pulley 37 is connected to reducer 33 through locking assembly 36, and a drive servo motor is installed behind the reducer. The reducer is mounted on eccentric flange 29, which is held by clamping flange 34. During assembly, eccentric flange 29 is rotated to adjust the center distance between the two pulleys.

There is a cam 23 on the right shaft. The cam can trigger the travel switch 19 during the rotation process, which serves as a signal for motor reversal and puts the trimming arm into a swinging working state.

A sleeve 39 is arranged radially in the middle position of the trimming arm, and a diamond pen 38 is installed on the sleeve. The diamond pen is fixed by a set screw. A nut 41 is installed on the rear end of the sleeve 39. By rotating the knob 45, the screw 40 can be driven to rotate. The screw drives the nut 41 to extend and retract the sleeve. At this time, the diamond pen can trim the busbar of the grinding wheel into an arc of 0~R70mm. The knob 45 is provided with a scale ring 44, each division is 0.02mm. When the knob is rotated one division, the sleeve extends 0.02mm.

A flange seat 52 is provided on the middle side of the trimming arm, and a diamond pen 51 is installed on it. The diamond pen is fixed by a set screw. A pin 48 is provided on the right side of the dressing arm, and a set screw 46 is provided behind the pin. The rotating screw 46 pushes the pin 48 to be inserted into the positioning sleeve 50. At this time, it cooperates with the electromagnetic power-off brake 28 to fix the dressing arm at the required angle position. At this time, the diamond pen 51 can trim the grinding wheel busbar into a diagonal line for grinding the bevel of the workpiece.

When the screw 46 is rotated in the reverse direction, the pin 38 is bounced away from the positioning sleeve 50 by the spring 47.

3.Application example

1) in the design of DVTG350×20/32l