Roll Grinding Method for Matched Pair of Rolls

Abstract

A method of grinding a pair of matching rolls in which the position of a grinding wheel relative to the rolls is computer controlled, and the surface profile of a roll is continuously measured and input to the computer comprising modifying the desired profile of the second roll of the matched pair adjusted by the residual shape error profile of the first roll to establish a uniform gap between the pair of rolls; and grinding the second roll to bring the profile of the second roll within acceptable tolerance based on the modified desirable profile.

Claims

1. A method of grinding a pair of matching rolls used in a strip rolling mill in which the position of a grinding wheel relative to the rolls is computer controlled, and the surface profile of a roll is continuously measured and input to the computer comprising the step of: inputting to the computer the desired profile and acceptable tolerance of a first roll of the matched pair; measuring and inputting to the computer the actual profile of the first roll; grinding the first roll to bring the profile of first roll within the acceptable tolerance; inputting to the computer the residual shape error profile of the first roll; inputting to the computer the desired profile and acceptable tolerance of a second roll; modifying the desired profile of the second roll of the matched pair adjusting by the residual shape error profile of the first roll to establish a uniform gap between the pair of rolls; and grinding the second roll to bring the profile of the second roll within acceptable tolerance based on the modified desirable profile.

2. The method of claim 1, in which the computer calculates the difference between the measured roll profile and the desired roll profile and adjusts the grinding conditions to reduce the difference.

3. The method of claim 1, in which the profile tolerance of the first roll is relaxed so as to reduce grinding time while still improving the accuracy of the nip.

4. The method of claim 1, in which the profile tolerance of the first and second rolls are relaxed to further reduce grinding time and achieve a nip accuracy comparable to one obtained without this method.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Further features and other objects and advantages will become apparent from the following detailed description made with reference to the drawings in which,

[0017] FIG. 1 is a schematic of a roll grinder, and

[0018] FIG. 2 is a high level diagram of the method according to this invention.

DESCRIPTION OF THE INVENTION

[0019] Referring to FIG. 1, a roll 10 to be ground is mounted for axial rotation and driven by the headstock 12. A grinding wheel 14 is indirectly mounted to a carriage 16 by an infeed mechanism 18. The carriage 16 translates the infeed mechanism 18 along an axis parallel to the axis of rotation of the roll 10. The grinding wheel 14 is mounted to the infeed mechanism 18. The infeed mechanism 18 drives the grinding wheel 14 toward and away from the roll 10, and drives the rotation of the grinding wheel 14.

[0020] A measuring caliper 20 is mounted on a carriage 22 to move parallel to the axis in order to measure the profile of the roll. A computer 24 receives profile information from the caliper 20. The computer 24 also receives position information from the carriage 16. A stored computer program controls the position of the carriage 16 and the infeed mechanism 18 such that with controlled grinding the profile of the roll is brought into tolerance. The computer is provided with manual input devices 26 such as a keyboard and a display device 28.

[0021] Modern automatic roll grinding machines already have the necessary control and measuring equipment and the required data collection and processing facilities for practice of the invention. The method can also be implemented in suitably equipped on-line grinding installations.

[0022] The standard procedure for grinding a single roll is as follows:

[0023] (1) Mount roll in machine.

[0024] (2) Acquire (from database) or specify target parameters:

[0025] (a) Diameter, this may be an absolute number, such as when it needs to match a previously ground matching roll or it may be relative, such as when we specify a minimum amount of stock removal to remove the work hardened layer; (b) ideal (target) profile and tolerance (max allowable deviation from ideal shape); (c) max allowable out of roundness; (d) desired surface roughness, typically an admissible range of Ra values; (e) desired surface quality, typically a subjective, visual assessment of (absence of) surface features (feed lines, chatter, grit marks, and shadows).

[0026] (3) Measure actual roll profile and alignment. If necessary, correct alignment mechanically.

[0027] (4) Residual horizontal misalignment will be compensated for electronically.

[0028] (5) Roughing: Optional phase to remove minimum stock.

[0029] (6) Shape correction grinding. In this phase measuring takes place on the fly and grinding continues until roll diameter and shape agree to within tolerance to target diameter and shape.

[0030] (7) Finish grinding: Successive passes to achieve roll surface quality, without changing roll shape.

[0031] (8) Remove roll from machine. The final measuring pass of the shape correction phase provides the values for out of roundness, the actual profile after grinding and the residual error profile.

[0032] The new method disclosed herein concerns the phase of shape correction grinding for roll pairs. It assumes that the difference between the two roll profiles defusing the gap, matters more than the individual shape profiles. The standard, existing procedure for grinding roll pairs simply applies the procedure for grinding a single roll twice. Typically, the target diameter for the second roll is set to match the diameter of the first roll.

[0033] Referring now to FIG. 2, the procedure for grinding pairs of matching work rolls comprises starting with the roll with the smaller diameter and grinding according to the procedure given above and saving the residual shape error profile.

[0034] For the second roll of the pair, the target profile in the shape correction phase is modified, adjusting it by the residual error of the first roll.

[0035] This results in a pair of rolls where the error in the gap between the two rolls no longer follows the sum of two error profiles, but the single error profile of the second roll.

[0036] Thus, in the same grinding time, a tighter tolerance for the gap than possible, by grinding the rolls independently, can be achieved.

[0037] Alternatively, one can shorten the shape correction grinding phase by relaxing the shape tolerance. One can do this for both rolls or one can relax the tolerance only on the first roll. The final error in the gap between the rolls will still correspond to the error profile of the last grind.

[0038] Having thus described the invention with the detail and particularity required by the Patent Laws, what is desired protected by Letters Patent is set forth in the following claims.