Straight wave vibration marks appear on the surface of the workpiece:
cause
1. The grinding wheel is unbalanced and the vibration is caused by the rotation;
2. The hardness of the grinding wheel is too high;
3. The wheel was not repaired in time after it became dull;
4. The grinding wheel has been repaired too thin, or the angle of the diamond has been blunt, and the grinding wheel is not sharp;
5. The peripheral speed of the workpiece is too large, and the center hole of the workpiece has a polygon;
The diameter of the workpiece is too large and does not meet the specifications of the machine tool;
6. The main shaft bearing of the grinding wheel is worn, and the clearance is too large, causing radial runout;
7. Loose bearing of headstock spindle;
Elimination method:
1. Pay attention to maintaining the balance of the grinding wheel;
The grinding wheel needs to be statically balanced twice;
After the grinding wheel is used for a period of time, if there is imbalance again, it must be statically balanced;
Before the grinding wheel stops, first turn off the cooling fluid to make the grinding wheel dry for dehydration, so as to prevent the cooling fluid from accumulating in the lower part and causing unbalance.
2. The hardness of the grinding wheel is too high: select the appropriate hardness of the grinding wheel according to the nature of the workpiece material.
3. The wheel was not repaired in time after being blunt: the wheel must be repaired in time.
4. The dressing of the grinding wheel is too fine, or it is more common that the apex angle has been blunt, and the grinding wheel is not sharp; choose the amount of dressing reasonably, or select the sharp angle to align the grinding wheel or re-weld the diamond.
5. The peripheral speed of the work piece is too large, and the center hole of the work piece has a polygonal shape; reduce the rotation speed of the work piece appropriately and repair the center hole.
6. The diameter and weight of the workpiece are too large to meet the specifications of the machine tool; instead, the grinding is performed on a grinder with a larger specification. If it is not possible to do so due to equipment conditions, the grinding depth and longitudinal feed can be reduced and the grinding wheel can be sharpened.
7. The main shaft bearing of the grinding wheel is worn, and the clearance is too large, causing radial runout; adjust the bearing clearance according to the instructions of the machine tool.
8. The headstock spindle bearing is loose; adjust the bearing clearance.
There are spiral marks on the surface of the workpiece:
1. The hardness of the grinding wheel is too high, the repair is too fine, and the grinding depth is too large; the hardness of the grinding wheel and the amount of dressing are reasonably selected, and the grinding depth is appropriately reduced.
2. The grinding wheel is too thin and not sharp enough; choose the amount of dressing reasonably.
3. The grinding wheel is too blunt; dress the grinding wheel.
4. Grinding depth, the longitudinal feed is too large, or the peripheral speed of the workpiece is too low; appropriately reduce the grinding depth, reduce the longitudinal feed or increase the speed of the workpiece.
5. Insufficient coolant; increase the coolant.
6. The ring material is excellent.
The workpiece has ellipticity:
1. The shape of the center hole is incorrect (not round, wrong angle, too shallow, burrs, etc.) or there are dirt, iron filings, dust, etc. in the center hole: the center hole can be repaired or wiped clean according to the specific situation.
2. The center hole or thimble is worn due to poor lubrication; pay attention to lubrication. If the center hole or thimble is worn, the center hole or thimble must be refurbished.
3. The work piece is too loose or too tight: readjust the pressure of the tailstock thimble.
4. The thimble does not fit tightly in the taper hole of the main shaft and the tailstock sleeve. Shaking occurs when grinding the workpiece: remove the thimble, wipe it off and reinstall it.
5. The wheel is too blunt: dress the wheel.
6. Insufficient coolant or untimely supply: ensure sufficient coolant.
7. The workpiece has poor rigidity and the shape error of the blank is large. The change in the grinding depth caused by the unevenness of the grinding causes the elastic deformation of the workpiece to change accordingly. As a result, the part of the workpiece after grinding retains the shape error of the blank : Grinding depth should not be too large, and gradually decrease as the margin decreases, and finally “smoothing” several times.
8. When the workpiece has unbalanced weight, due to the influence of centrifugal force, more metal will be ground off on the heavier side, so that the workpiece has ellipticity.
9. The clearance of the spindle bearing of the grinding wheel is too large: adjust the clearance of the spindle bearing.
10. When grinding the outer circle with chuck clamping, the radial runout of the headstock spindle is too large: adjust the headstock spindle bearing clearance.
The workpiece has taper:
1. The worktable is not adjusted properly, and the axis of rotation of the workpiece is not balanced with the movement direction of the worktable: carefully align the worktable.
2. The elastic deformation of the workpiece and the machine tool changes: the worktable should be carefully aligned with the sharp grinding wheel. When the first workpiece is being finely ground, the sharpness of the grinding wheel, the amount of grinding and the number of “light grinding” strokes should be basically consistent with the situation of finding the right job. Otherwise, it needs to be removed with uneven cutting.
3. The lubricating oil pressure of the guide rail of the worktable increases, and the swing occurs during operation: adjust the lubricating oil pressure of the rail.
4. The center lines of the thimble of the headstock and tailstock are not vertical, one end is high and the other is low: wipe the contact surface of the tailstock and the worktable so that the centerlines of the front and rear thimble coincide.
The workpiece has a drum shape:
1. The rigidity of the workpiece is poor, and elastic bending deformation occurs during grinding: reduce the deformation of the workpiece: ○1 reduce the grinding depth, and finally make more “light grinding” strokes.
2. Dress the grinding wheel in time so that it always maintains good cutting performance.
3. When the workpiece is very long, an appropriate number of center frames should be used.
2. Improper center adjustment: Correctly adjust the pressure of the support block and the support block on the workpiece.
7. The size of the two ends of the workpiece is smaller or larger
1. Too much or too little of the grinding wheel beyond the end face of the workpiece: Correctly adjust the position of the commutation stop on the worktable so that the width of the grinding wheel beyond the end face of the workpiece is about 1/3 to 1/2.
2. The dwell time is too long or short when the worktable is reversed: adjust the dwell time correctly and carefully.
The size of the outer circle next to the stage is larger:
1. The short stay of the workbench during commutation: extend the stay time.
2. The grinding wheel is worn, and the outer corner beside the step becomes round or the bus bar is not straight: dress the grinding wheel.
There is beating on the end of the stage:
1. When the knife is too large and the knife is retracted too fast, the vertical shaking table should be slow and even, and there is no spark in the “light grinding”.
2. Insufficient coolant: increase the coolant.
3. The work piece is too tight or too loose: adjust the pressure of the tailstock.
4. The spindle of the grinding wheel has axial movement: repair the machine tool.
5. The clearance of the thrust bearing of the headstock spindle is too large: adjust the clearance of the thrust bearing.
6. When grinding the end face with chuck clamping, the axial movement of the headstock spindle is too large: adjust the gap between the thrust and bearing.
Raised inside the end face of the stage:
1. The feed is too fast, and the polishing time is not enough: the feed is slow and evenly “smoothed” until there is no spark.
2. The contact area between the grinding wheel and the workpiece is large, and the grinding pressure is large: the end face of the grinding wheel is made concave to narrow the working surface as much as possible. At the same time, the grinding wheel is withdrawn after a certain distance before eating the knife, and then gradually shaken into the grinding wheel to grind out the entire end face.
3. The centerline of the spindle of the grinding wheel is not parallel to the movement direction of the workpiece: adjust the position of the grinding wheel frame.
Different axis of each outer surface of the stage axis:
1. Same as ovality reasons 1 to 5: same as eliminating ovals 1 to 5.
2. Excessive amount of grinding and insufficient time for “light grinding”: reduce the depth of fine grinding.
3. Surfaces with high coaxiality requirements should be divided into rough and fine grinding: the grinding steps should be properly arranged.
4. Use the chuck clip to find the work piece or the headstock spindle bearing jumps too much: find the work piece carefully: adjust the spindle bearing clearance.
