FI108930B - grinding Process - Google Patents

Description

108930 GRINDING METHOD

The invention relates to a grinding method as defined in the preamble of claim 1.

The invention is particularly directed to the grinding of cylindrical paper machine rolls, but may also be used in other types of grinding of surfaces of elongated cylindrical or conical bodies. In the following, however, the invention will be mainly described with reference to cylindrical paper machine rolls.

Heavy and relatively long paper machines are generally stored by hanging them on their hubs, whereby they bend under their own weight, i.e. they curve downward in relation to the straight between their hubs.

As the roller is rotated again, it will slowly begin to straighten and approach the line between the hubs. The speed and magnitude of the phenomenon is proportional to the time the roll has been grounding without rotating in the warehouse. Typically, it is hours to several days.

When the bent roll 20 taken out of storage is ground to grind, unnecessary bending of working time occurs, since the roll has to be rotated in the grinder for several hours before grinding can begin. When grinding, rarely has the roller been completely successful,. so that during grinding, the grinding pressure and the material displacement • · '25 will vary according to the roll roll. In this way, the roll is unnecessarily machined and material is removed *. * ·· in the wrong places to achieve the desired roll rotation and length profile.

If the roll was originally round but 30 bent during storage, the roll may have been sanded. round when awaiting its straightening. If you want your baby to be round in cross-section, you will need to sand it until it is sufficiently straightened or settled to a sufficient 35 stable position after rotation and then for so long. that a malformation resulting from abrasion is obtained, ·. ; you sanded away.

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Once the roll has been sanded, it is often put back into storage where it begins to bend again. When installed in a paper machine, the roll may be as bent as before grinding.

The object of the invention is to eliminate the above disadvantages. In particular, it is an object of the present invention to provide a novel grinding method which provides the most commonly used single-disc machines with the same grinding accuracy previously obtained only by using two-disc floating stone suspension machines.

As regards the aspects of the grinding method according to the invention, reference is made to the claims section.

It has been found in the invention that the effect of the deflection of the roll 15 can be compensated using a suitable control system. The grinding stone can be made to follow the target circumference of the roll in addition to the desired length profile, whereby only the roughness and other surface defects are removed from the roll. By taking into account the shape of the deflection and its marsh crossing during grinding, the roll is made round in the shortest possible time.

In the method of grinding according to the invention, the parts to be sanded in a circular section of elongated sections: '··; V 25 around its axis. In addition, the grindstone is rotated: and its position is adjusted on the surface of the object to be sanded so that the grinding point of the sandstone is maintained at a substantially constant distance from the actual, ··· point of the object being sanded. regardless of the deflection of the body.

According to the invention, the position of the grindstone is adjusted to the rotation of the roll by a synchronized oscillating position adjuster, which receives feedback from a measurable quantity that is linearly correlated with the position change of the surface to be ground.

3 5 The method uses an analyzer that calculates the average vector value (amplitude and phase angle) of the roll surface from the instantaneous measurable quantity, such as' · '' distance, and the roll position, or the distance between the roll and the roll position. This vector value represents the eccentricity of the roll. The controller then integrates the eccentricity vector and controls the 5 oscillators.

The measured quantity may be electrically or optically measured surface distance. The quantity may also be the input power or current or pressure of the abrasive wheel pressing against the abrasive surface. It is essential that the quantity to be measured correlates linearly with the position change.

Preferably, the output of the oscillating positioner is summed with other abrasive positioning signals, such as contour curve, body error correction, and current abrasion value, whereby the compensation cooperates with other abrasive modes.

Preferably, the length of the axis of the part formed by a mathematical function is used in the adjustment.

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and a deflection model approximating the shape of an acceptable 20 physical deflections. Preferably, the bending pattern is adaptive and follows the alignment of the part during grinding. An acceptable form of eccentricity may be approximated by, for example, a sine function.

By the abrasive method of the invention, the abrasive: V can be started immediately when the roll is removed from the cast, without having to wait for its straightening.

. ···. This significantly reduces grinding times.

In addition, the rolls provide a better overall profile than the present one.

The method of the invention can generally be used in rotary grinding to correct for eccentricity caused by a workpiece homogeneous behavior in the rotational direction. Particularly, installing large 3 5 and heavy pieces centrally is • t laborious and time consuming. This method saves installation time and improves the quality of the sanding result.

When using the grinding method of the invention, the offset, the surface shape and the longitudinal profile of the roll are also indirectly measured.

In other words, the three-dimensional shape profile measurement of the roll shell is produced as a by-product of grinding. This information can be used in roll maintenance to evaluate roll condition and grinding performance. This system 10 is not a measuring device and its absolute accuracy cannot be demonstrated to the measuring device as required. However, when used in combination with a known reference measuring device, this may achieve the measurement accuracy required for maintenance grinding without using any time for 15 measurements.

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Claims (7)

108930 1. Grinding method for single-disc grinding of substantially circular cross-sectional elongated bodies, such as cylindrical paper machine rolls, wherein: - the grinding block is rotated about its axis; irrespective of the center axis of the body deflection, characterized in that - the grindstone position is adjusted to the roll rotation by a synchronized oscillating positioner, which receives feedback from a measurable quantity that correlates linearly with the position change of the surface to be sanded. Grinding method according to Claim 1, characterized in that the positioner receives feedback from the grinding power input. A grinding machine according to claim 1; ': characterized in that the positioner .V: receives feedback from a distance measurement of the surface of the body to be sanded: 25 autumn. | . * ··. Grinding method according to claim 1, characterized in that the output of the oscillating positioner is summed with other grinding positioning signals. • »· f * The abrasive method according to claim 1, characterized in that the control uses: 'j a longitudinal deflection model of a body axis formed by a mathematical function, which approximates the * * shape of an acceptable physical deflection. '35 Grinding method according to claim 5, characterized in that the deflection pattern is 108930 adaptive and follows the straightening of the part during grinding. Grinding method according to claim 5, characterized in that the acceptable form of non-centrality is approximated by a sinusoidal function. 108930