Toothing for operation at a deflection angle and production method

A toothing, in particular of a drive spindle for driving a roll in rolling mills or continuous casting plants, which has several teeth and meshes with a second toothing in the manner of a spline, wherein a flank line of the teeth has a curvature, and a deflection angle is formed between the rotational axis of the second toothing and the rotational axis of the drive spindle toothing, and wherein the teeth of drive spindle toothing have a twist in form of profile angle deviation over the tooth width in the flank direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of toothings and, in particular, to a spline toothing having a first toothing engaging in a second toothing of a drive spindle for driving, e.g., a roll in a rolling mill or a continuous casting installation. The invention also relates to a device including such toothing.

2. Description of the Prior Art

In known applications, force transmission from a drive to a shaft at an angle is required. This requirement often arises, e.g., in rolling mills. E.g., if two working rolls are arranged one above the other, then, because of their relative small diameters, a problem arises when an increase of the transmitted torque is desired. If the transmitted torque increases, the working roll diameters need also be increased which, among others, leads to the energy losses. In addition, in this case, the rolling mill stand should be formed more robustly.

Therefore, the existing systems include universal joints arranged between the drive spindle and the roll, however, the requirements of an increased torque transmission are still not justifyingly met.

If splines are used for arranging the drive spindle at an angle to the roll, the drive spindle can be formed so that it is able to transmit a greater rolling mill torque, nevertheless, classical toothings, which are conventionally used in drive spindles, lead to edge loading which causes a very high wear and, as a result of which, no transmission of a desired high torque is possible.

The object of the invention is to be able to provide, between a toothing and a complementary second toothing, a deflection angle with which a greater torque can be transmitted than was the case up to now.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved for the above-mentioned toothing by forming the teeth with a twist in form of a profile angle deviation over a tooth width in direction of the flank.

With this profile modification, the first toothing can be driven at a deflection angle relative to the second toothing and can transmit a greater torque than was the case without the modification. In particular, the undertaken modification reduces the edge loading and provides for the increased torque transmission. Advantageously, two or more modifications can be combined, e.g., relief of the tooth root and/or the tooth tip can be combined with the tooth twist to further improve the characteristics of the toothing.

Within the meaning of the invention, the relief of the tooth root and/or the tooth tip and the tooth twist means that the profile line falls back in comparison with the conventional profile and, in particular, in the contact region of the teeth flanks during normal operation.

Further, the invention permits to increase the torque transmitted from a drive spindle to a roll and/or to increase the deflection angle between the drive spindle and the roll. Without the above-discussed modification, the carrying section of the flank becomes smaller at an increased deflection angle that is greater than zero, so that with the increased deflection angle, less torque can be transmitted. With the inventive toothing, the load can be uniformly distributed over the tooth height. Thus, e.g., the drive spindle can transmit, in certain cases, a torque increased by 50%, whereby greater strip widths can be rolled. With a further increase of the transmittable torque, the working rolls even can be made smaller.

According to an advantageous embodiment of the toothing, the toothing is formed as an involute toothing, whereby the tooth roots and/or tooth tips can be advantageously, but not necessarily, relieved at least parabolically. The relief can be produced at the generating line and/or at the tooth profile. The at least parabolic relief should be understood as a relief with which the profile difference between the theoretical flank of an involute toothing and the inventive relieved flank is a function of an increase of a roll-off path over the profile of the involute toothing at least with about second power. That is why the relief is advantageously substantially parabolic.

With the parabolic relief of the tooth root or tip, the edge loads can be reduced and, thereby, the torque transmission can be improved.

In a further advantageous embodiment of the toothing, the tooth roots are relieved at a root circle by from 0.2% to 3% of a tooth thickness at a pitch circle, and/or the tooth tips are relieved at a tip circle by 0.1% to 2% of the tooth thickness at the pitch circle.

With these values of the profile modification of each tooth, the force transmission can be optimized during engagement of the toothings.

According to a further advantageous embodiment of the toothing, the tooth tip relief is provided between 50% and 70% of the tooth height and/or the tooth root relief is provided between 50% and 60% of the tooth height.

The above-mentioned values for the relief of the tip or root with respect to the tooth height permit to further optimize the transmittable torque.

In a still further advantageous embodiment of the toothing, an involute line of the teeth is symmetrically curved in a width direction. Under the involute line, as known, the bottom between two adjacent teeth is understood.

By forming a curved involute line, the torque transmission can be further increased. According to a yet further advantageous embodiment of the toothing, a curvature of the flank line is so formed that difference between a greatest thickness of each tooth at a height of the pitch circle and a smallest thickness of each tooth at the height of the pitch circle corresponds to a value between 3% and 20% of the greatest thickness of each tooth at the height of the pitch circle.

This feature makes advantageous profile of the curvature of the flank line more precise.

According to a further advantageous embodiment of the toothing, the twist of the teeth is formed by a maximal profile angle deviation between 0.3° and 1.5°.

This is a relatively small value of the twist noticeably improves the torque transmission during engagement of the toothing in the second toothing at an angle.

In another advantageous embodiment of the toothing, the twist of the teeth is formed substantially parabolic in direction of the tooth flank. This means that the profile deviation, as a function over the tooth width, has essentially a parabola-shaped profile.

The basic shape of the toothing is produced as a result of reduction of the basic shape, e.g., by milling and the like. The subsequent treatment for obtaining the inventive toothing can follow by grinding in a free-movable machine-tool, e.g., a 4-axes and 5-axes machine-tool.

Advantageously, a curved-back toothing is obtained, after production by a classical method as involute toothing, by the parabolic relief of the tooth root and/or the tooth tip by subsequent treatment.

The after treatment is carried out by at least one of grinding process or by grinding each tooth flank.

The invention further includes a device for driving a roll of a metallurgical installation and including a shaft with a toothing according to present invention. Such a shaft can, e.g., be set in a corresponding opening in a roll and/or a motor in a manner of a spline toothing. The opening can be provided, in particular, with an inner toothing that can likewise be formed according to the invention. The inner toothing can be formed, in a possible embodiment, in which the shaft or the inventive toothing is displaceable by a predetermined stroke, as a spur toothing.

In an advantageous embodiment of the device, the inventive toothing is provided at both ends of the shaft. This provides an intermediate shaft that, e.g., is connectable at both end by an inclined spur toothing, and, thus, enables transmission of a particular large torque at a particular large angle or a predetermined angle.

In an advantageous embodiment, the shaft and the roll are arranged relative to each other at a deflection angle of more than 0°, in particular more than 0.2°. Particularly advantageously, the deflection angle does not exceed 3°, in particular, lies between 2° and about 3°.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be noted that one of ordinary skill in the art is familiar with terms such as pitch circle, tip circle, root circle, surface line, flank line, pressure angle, twist and others and, therefore, they will be used in the following description without any further explanation. Below, a brief explanation of less common definitions of the profile angle deviation and twist are provided. Profile angle deviation is defined as a deviation of the standard profile angle. The profile angle is the angle between a cutting edge or a cutting surface and a principal direction. The profile angle deviation is normally intended to be constant, any deviation is traditionally considered as manufacturing fault. The twist however is an intended, specially machined profile angle deviation following a certain mathematical rule.

FIG. 1schematically shows a cross-section of a flank of a tooth2of a toothing1. The flank line is convexly bent, and therefore, basically, one can speak of a curved-back toothing. On the right of this flank, a tooth gap3is seen. The rotational axis of the toothing1extends perpendicular to the shown cross-sectional plane. The pressure angle α of the toothing can have different values, in particular, it can advantageously amount to values between 26° and 34°. The line6represents the profile line of the tooth2in form of a classical involute line6of a known involute toothing. Though, according to the invention, the root4and/or the tip5can assume, preferably, other forms ground with respect to a classical involute form. The relief of the tooth tip5is shown with line7, and of the tooth root4with line8. The relief of the tooth tip5at the tip circle is schematically shown by a path or spacing A-A. The radii or diameters, with which the relieves of the tooth root4and or of the tooth tip5are set, are shown with reference numerals9,10. Between the points9and10, the profile of the flank of the tooth2corresponds, preferably, to an involute shape6, however, it can be described by other conventional profiles. The tooth tip relief and the tooth root relief, which are shown inFIG. 1, are shown at a substantially increased scale, and they should be understood as only schematic. The same applies to radii9and10. The tooth root relief can have different values, however, they amount, preferably, at the tooth circle, between 0.2% and 3% of the tooth thickness measured at the pitch circle, wherein the thickness direction extends transverse to the width direction of the toothing1. The tooth tip5preferably has a relief from about 0.1% to 2%, at the tip circle or at the height of the tip circle, of the tooth thickness (measured at the pitch circle). The relief of the tooth tip5starts, preferably, between 50% and 70% of the tooth height, and/or of the tooth root4between 50% and 60% of the tooth height. The tooth height is defined as difference of radii of the tooth tip and the tooth root. In other words, it means that the tip and/or root relieves are set at radii which correspond to the above-mentioned percentage parameters of the difference between the tip and root circles radii.

FIG. 1ashows a schematic perspective view of the tooth similar to the tooth shown inFIG. 1and showing modification of the tooth generating line with the tip relief7and the root relief8.FIG. 1bshows, correspondingly modification of the tooth profile with the tip relief7and the root relief8. To show more precisely the effect on the outer contour of a tooth the originally rectangular contour (solid lines) is superimposed by the modified contour (with dash lines).

FIG. 2likewise shows a schematic cross-section of an inventive toothing1, however, here, only the curvature or the modification of the involute line is emphasized. The view should be understood as two-dimensional. Only tooth2of the toothing1and a tooth gap3between the teeth are seen. The line at the upper end of the left tooth2represents the highest position in the width direction (direction of the rotational axis of the toothing or, in the future in Z-direction) of the involute line. The lower limiting line of the left tooth2represents the involute line at the edge of the toothing1, as seen in the width direction. The curvature of the involute line is advantageously obtained by grinding a classically formed or produced toothing. However, other known manufacturing processes can be used. The curvature, preferably seen in the width direction, is mirror-symmetrical towards the middle of the toothing1and is curved particularly outwardly or is convex.

The line B-B inFIG. 2defines a cross-sectional plane which is shown and clarified inFIG. 3. The cross-sectional plane B-B passes through the intersection of the pitch circle of the toothing1with the involute6of a tooth2.

FIG. 3shows a plan view of the flank line12of the right flank of the tooth2. The line C-C shows half of the middle axis of the tooth2and that extends transverse to the width direction Z, i.e., in the thickness direction of the tooth2. On the right side ofFIG. 3, a rectangle is shown which represents a cut-out shown inFIG. 4.

FIG. 4shows an end of the flank line12as seen in the width direction Z. The line D-D shows the relief of the flank line12at a first location. The flank line12is in particular, curved outwardly or is convex. The relief of the flank line12can be obtained preferably by grinding, however, other known processes can be used.

The flank line modification or the relief of the flank line12at the rim of the toothing1has a size of the line E-E, when seen in the width direction. The size in the drawing should be understood as purely schematic. The relief of the flank line at the rim of the toothing1in the width direction can advantageously amount to form 3% to 20% of the thickness of a tooth2of a spur toothing or from 3% to 20% of the thickness at the point of the maximum thickness of the tooth2at the height of the pitch circle.

Generally, the relief of the flank line inFIG. 4is seen, in the width direction, at the rim of the toothing1but more pronounced that shown by the line E-E. Further, the shown relief, in this case, on the spur tooth2, is produced by an optional twist, i.e., by a twist.

Such twisting of the tooth can be described by changing the profile angle in the Z-direction or the flank direction of the tooth2. An example of such profile angle change or twisting is shown in diagram ofFIG. 5and inFIGS. 5aand5b.

FIG. 5shows a parabolic profile of the twist in Z-direction. The profile angle deviation (φ) is shown in degrees with respect to the width of the toothing1in the Z-direction. The numbers in the Z-axis are given only as examples for a width of the toothing1from φ up to 110, wherein the line unit represents an arbitrary length value. It can be seen that the profile angle deviation in the middle of the toothing1in the width direction equals almost zero and falls out at most at rims of the toothing1. In this example, about 0.5° at the rim. However, other values of twists are possible such as, e.g., twists with a maximum deviation of the profile angle φ between 0.3° and 1.5°.

FIG. 5ashows the profile angle deviation (φ) over the tooth width Z (in Z-direction, e.g.,110). As can be seen inFIGS. 5 and 5a, the profile angle deviation in the middle of the tooth width is O, i.e., the twist angle φ=O.

To show more precisely the outer contour of the tooth shown inFIG. 5a, the originally rectangular contour (solid lines) is superimposed by the contour showing the twist (dash lines).

According to the invention, to flank curvature modification resulting from the tip and root relieves can be combined with the twist modification as shown inFIG. 5b. In this case the best results are achieved.

FIG. 5bshows a comparison of the tooth contour according to the invention with twist and additional tip and root relieves (dash-point line) in comparison to a contour with only tip and root relieves (full line). The comparison is in an exaggerated manner to point out the effect of the twist towards the contour of the tooth.

In summary, the above-mentioned profile angle values are valid for a deflection angle β (seeFIGS. 6 and 7) between the first toothing and a second toothing, preferably, an inner toothing, between 0° and 5° and particularly advantageous between 2° and 5°.

The second toothing can have its rotational axis lying directly on the axis of a roll. In addition, the second toothing can be directly integrated in the roll or lie in an attachment directly connected or connectable with the roll journal, wherein its rotational axis preferably coincides with that of a roll. As generally conventional, such an attachment connects the roll with the drive spindle.

The toothing1described with reference to different embodiments, is preferably a spur toothing, i.e., preferably is not cut obliquely. The same applies to the second toothing which is formed, e.g., by an inner toothing.

In particular, the toothing1can be provided in a drive spindle for driving a roll, as shown inFIGS. 6 and 7, which is provided in rolling mills of various types. The construction of such drive spindles is generally known. The toothing1can be formed as one piece with a drive spindle or be mounted on the drive spindle.

The device for driving two rolls13of a rolling mill, which is shown inFIG. 6, has, for each of the rolls13, an output shaft (not shown) of a motor or motor drives14, wherein an intermediate shaft15is arranged between the rolls13and the output shafts14, respectively.

The intermediate shaft15has, at each of its ends, the inventive toothing16,17, respectively. The toothing17engages in an inner toothing19of the roll13in spline-like manner, and the other toothing16engages in the inner toothing18of the output shaft14. The intermediate shaft15is arranged at an angle relative to the roll13and relative to the output shaft14. Thereby, a noticeably greater distance of the output shafts14or the motors and/or drives from each other becomes possible, which corresponds to the distance between axes of the rolls13.

The inner toothing18of the shaft14is formed as spur toothings, whereby in accordance with the requirements, the inventive spur toothing can be used.

The inner toothing18enables displacement of the engaging toothings16of the intermediate shafts15in the axial direction by a maximum stroke, whereby per se known axial displacement of the rolls13during a rolling process is possible.

The above-mentioned features can be arbitrarily combined with each other. In addition, one of ordinary skill in the art can change constructive particularities to a different shape.