DK142757B - PROCEDURE FOR GRINDING DENTAL FLANGE AND APPARATUS FOR EXERCISING THE PROCEDURE - Google Patents

Description

(11) PUBLICATION NOTICE 1 ^ + 2757 DENMARK (51) Int. Cl.3 F 16 H 65/08 UMmviMmv F OA C Section 2/10 (21) Application No. 4055/71 (22) Filed on 19 · ^ Ug · 1971 (24) Race day 19 * auS * 1971 (44) The application presented and "

the petition published on I d. · J oil · I yo I

DIRECTORATE OF

PATENT AND TRADEMARK (3 °) Priority requested from it

Aug 20 1970, 2041485, DE

(71) PRINCIPAL HOHENZOLLERNSCHE HUETTENWALTUNG LAUCHERTAL, Laucher = Valley / Hohenzollern, DE.

(72) Inventor: Hermann Haerle, Hauptstrasse 54, D-7501 Freiolsheim, DE: Siegfried Eisenmann, Schubertstrasse 8, D-7107 Neckarsulm, DE.

(74) Plenipotentiary in the proceedings:

Office for Industrial Excellence by Swend Schønning.

(54) Method of grinding tooth flanks, and apparatus for practicing the method.

The present invention relates to a method of grinding tooth flanks on an internally toothed gear, whereby the tooth flanks are abraded while the internally toothed sprocket is rotated about its axis at a predetermined speed, and the axis of the internally toothed sprocket is rotated simultaneously with a different one. velocity about another axis parallel to the axis of the internally toothed gear and having a distance from it equal to the radius of a basic circle minus the radius of a rolling circle which, upon rolling on the inside of the basic circle, produces a cyclo-2 And an apparatus for practicing the method.

The prior art is represented by Swiss Patent No. 125,534 and U.S. Patent No. 2,091,317.

Swiss Patent No. 125,534 discloses a method and apparatus which enables teeth to be formed according to cyclic curves such as hypocycloids.

The appearance of the cycloids produced according to this Swiss patent is shown in Figures 12 and 13. Such cycloid profiles are less suitable for normal teeth. In practice, only one tooth form has been found for internally toothed ring wheels of the one shown in FIG. 13 of the Swiss patent or fig. IA of U.S. Patent No. 2,091,317. However, such a tooth shape is not suitable for gear pumps or motors with a large pressure drop, as the seal becomes very poor at the point where the internally toothed gear teeth engage with the toothed exterior gear teeth.

Instructions on how to grind a suitable tooth flank shape on an internally toothed ring wheel by a roll-off method cannot be deduced from the Swiss patent. There are no indications in this direction in the Swiss patent.

The above-mentioned disadvantage of the tooth shape according to the Swiss patent is noted by the author of the a-merican patent no. 2,091,317. He solves the problem of providing a more favorable tooth shape after starting from the one in FIG. IA or IB of the US patent showed tooth shape in which each tooth of the ring wheel is restricted by a cycloid arc after manufacturing the externally toothed, internally placed cogwheel to use this as a planing or impact tool and then planing it in FIG. IA or IB in tooth contour indicated ring wheels.

See page 3, right column, last paragraph and page 4, left 35 column, first paragraph of the US patent. At the completion of the gearwheel, a half-toothed drive serving as an external toothed gear rotates as a toothed tool. Then a new planing process takes place (of course, for that matter, the wheel ring must also be pre-worked, while the tooth spacings 40 which appear in this way cannot be completely finished with a single planing stroke). In this way, it is shown in FIG. 1, which now has a significantly more favorable tooth shape.

The same applies to the production of the gear pair according to FIG. II. There, the drive is rotated after planing it in FIG. IB indicated the ring wheel not a half tooth split, but merely a third of a tooth split, whereby a further round of tooth gaps is planed in the ring wheel. After further rotation of the drive, an additional third part of the tooth 10 is planed in a third rolling process the third group of tooth loops in the ring wheel.

The US patent does not specify any technical teachings on how the ring flanks can be sanded. The grinding cannot be done by the rolling process according to Swiss Patent No. 125,534. According to the United States patent, it is required to make one according to FIG. IA and IB more favorable tooth shape a rotation of the impact tool, which has the same contour as the drive, a fraction of a tooth split. This rotation can occur only by a partial method. This results in a corresponding tooth failure. In addition, according to the US patent, it is not possible to sand the wheel ring; it is only possible to plan this one.

Based on this state of the art, the present invention solves the task of continuously producing a hypocycloid tooth of the steering wheel wheel ring approximately as shown in FIG. In the US patent. This is provided by the invention by choosing a cycloid shape in which a cycloid, which determines the tooth contour of the wheel ring, does not recede itself after a single orbit of the rolling circle forming the cycloid on the basic circle, but that the cycloid only after at least two circuits coincide with themselves.

For example, if the wheel ring has nine teeth, the diameter of the roller circle may have the following fractions of the diameter of the base circle: 2/9, 4/9, 5/9 and 7/9. Since now, as can be mathematically proved, two rolling circles whose combined diameter is equal to the diameter of the basic circle produce the same cycloid, only two cycloids can be spoken, one with a rolling diameter of 2/9 or 7 / 9 and another with a roll circle diameter of 4/9 or 5/9 of the diameter of the base circle. In the latter case, the tooth height can be kept low and the tooth gap is sufficiently wide by selecting a sufficient distance from the line for equal distance from the cycloid.

Already in a gear with, for example, twenty teeth, the choice of the cycloid is considerably greater due to the higher number of teeth. Here the ratio of roller circle diameter to base circle diameter can assume the values 1/20, 3/20, 10 7/20, 9/20, 11/20, 13/20 and 17/20. Because of the equivalence of 3/20 and 17/20, of 7/20 and 13/20 and of 9/20 and 11/20, three possible cycloids are thus obtained.

In the conditions specified in claim 1, by grinding the tooth flanks by means of a grinding wheel rotating about an axis parallel to the outer wheel ring, the grinding wheel axis moves relative to the outer wheel ring on a hypocycloid which results from rolling a roller circle. if the descriptive point of the cycloid reaches its starting position after two whole circuits around the center of the basic circle.

Hereby, in a rolling process, steeper teeth flanks can be sharpened than has hitherto been possible.

This advantage is obtained regardless of whether or not the grinding wheel axis is parallel to the wheel ring axis.

FIG. 5 shows, as an example, a cycloid with its 25 equidistants, which after two circuits cycloid recedes into itself and thus produces a seven-tooth wheel ring.

With seven teeth, in practice, only two turns can be selected. At greater number of teeth, such as, for example, 21 teeth, 30 as shown in FIG. 6, one chooses so that the teeth do not get too flat a shape, preferably a cycloid, in which the point describing the cycloid returns to its starting point on the basic circle after four turns.

FIG. 7 shows, as an example, an outer wheel with sixteen 35 teeth, at which the rolling circle point, which describes the cycloid, returns to a starting point after having run about the basic circle three times. It is already apparent from these few examples that by selecting the number of roll circle turns for a given number of teeth, it is possible to determine to a large extent the tooth shape.

142757 5

In the case of smaller tooth numbers, two or three orbits are usually required.

It is evident that by choosing a correct ratio of roller circle diameter to base circle diameter 5 within the limits given above, a correspondingly greater freedom to choose the tooth shape is obtained as the number of teeth grows.

With a small number of teeth, such as for example with seven teeth on the wheel ring, only a small amount of freedom is obtained. Here, the roller circle diameter must relate to the basic circle diameter as 10 2/7, 3/7, 4/7 or 5/7.

The rolling circle point describing the hypocycloid and hypocycloids, respectively, is preferably located on the rolling circle. Deviations from both the inside and the outside of the roller circle should usually be small.

When, when swinging about its axis through the tips of the cycloid, the grinding stone is not to grind two tooth flanks at the same time and the wheel ring blank is not processed to allow this, then preferably after the grinding of all the tooth flanks is turned on one side of the teeth and after resetting the grinding stone. in the starting position, the wheel ring about its axis without rotation about the other axis a certain distance relative to the grindstone, after which all the teeth are grinded on the other tooth flank in the same way.

The invention also includes an apparatus for carrying out the method described above. The apparatus comprises a pedestal, an eccentric shaft, which together has two shaft portions extending parallel but eccentric to each other, the first of the two shaft portions being pivotally mounted in the base with a pivot table mounted on the other shaft port, of which the internally toothed sprocket to be ground may be clamped so that the axis of the sprocket coincides with the axis of the other shaft portion, and with a drive for rotating the eccentric shaft in the socket and for turning the table on the eccentric shaft, the socket being provided with a grinding device 35 for the tooth flanks, the additional eccentricity of the eccentric shaft being equal to the difference of the basic circle of a cycloid and the radius of a rolling circle which produces this cycloid as it rolls on the inside of the basic circle.

According to the invention, the apparatus is characterized in that an externally toothed gear ring is arranged concentrically and pivotally relative to the first shaft part, that an internally toothed gear ring is arranged concentrically with the second shaft part, that the eccentric shaft has a number of 5 each other. interfering sprockets, that one of these sprockets engages the externally toothed gear, while another engages the internally toothed sprocket, that the ratio of the radius of the roller circle to the radius of the basic circle is a shortened fraction that the denominator in this fraction is at least equal to the number of teeth of the internally toothed gear, that the count of the fraction is at least equal to two and at most equal to the number of teeth of internally toothed gear minus two, and that the ratio of the rotational speed of the eccentric shaft to the rotational speed table 15 is equal to the ratio of radius of the basic circle to the ratio of radius of the basic circle and the radius of the cycloid roller circle.

Preferably, the abrasive means of the grinding device are displaceable in the circumferential direction relative to the bearing of the eccentric shaft.

The invention will now be described in more detail by way of example with reference to FIG. 1-4.1 in this connection, it should be pointed out that the illustrations of the apparatus according to the invention are simplified as much as possible in order to make the principle of the apparatus more clear.

FIG. 1 shows the geometric conditions of a ring wheel according to the invention; FIG. 2 schematically shows an apparatus for grinding a hollow wheel according to the invention; FIG. 3 shows the eccentric shaft of the apparatus according to the invention; FIG. 4 shows a section IV-IV in FIG. 2nd

FIG. Figure 5 shows an example of a cycloid with its equidistants, which cycloid recedes itself after two cycles.

FIG. 6 is a view similar to FIG. 5 shows a cycloid which recovers itself after four circuits; and FIG. 7 is a view similar to FIG. 5 and 6, a cycloid that recovers itself after three turns.

142757 7

The preparation of the tooth on the ring wheel will be explained in greater detail by means of fig. 1. On the ring wheel portion shown there, the basic circle F has radius rF. The hypocycloid H determining tooth flanks is formed by unrolling 5 a rolling circle R with radius rR on the base circle F. The point P on the rolling circle thus describes the cycloid. The same cyclo-idea also arises when rolling a rolling circle R 'with radius R' = rF-rR on the basic circle in the reverse direction. In the example shown, the cavity wheel 1 has nine teeth. Similarly, as described above, the radius of the rolling circle R must be equal to 2/9 or 4/9, respectively radius R '= 7/9 or 5/9 of the basic circle radius when an Eaton tooth is not spoken. At 4/9, as already fig. 3 shows that the tooth height becomes so large that the teeth for a flawless engagement 15 can no longer have edge-shaped tooth heads, but a corresponding tooth head surface. This is a disadvantage for the necessarily very small number of inner wheels. Therefore, a ratio of the rolling circle diameters rR to the basic circle diameter rF of 7: 9 or 2: 9 is chosen. For preparation 20 of the hollow wheel, the abrasive disc 7 is now moved with its axis along the simply-wound hypocycloid H. Thus, the circumference of the abrasive disc 7, having a radius rS, describes an equidistant E to the hypocycloid H. As seen in the drawing, flanks 1a and 1b of two adjacent teeth of the hollow wheel turned apart. Rather, it touches alone (seen from the center of the cavity) at all times the right flank 1b of a tooth, thereby precisely acquiring the shape of an equidistant.

On the left flank 1a of the tooth, the grinding wheel 7 goes free. Thus, the reaction force acting on the grinding wheel during grinding is less. Further, when grinding the grinding wheel, it can be made at the right tooth flank. As can be seen further from the drawing, the ring wheel blank is processed before grinding and curing so that in an area outside the basic circle it is released from the grinding wheel. In this area that is not 35 abrasive, there is no contact between hollow and inner wheels. Here the teeth are only ground in the area lb.

Already out of the short preparation ± fig. 1 it is seen that in the manner according to the invention, i. guiding the axis of a grinding spindle along a hypocycloid of the type defined above, can grind a flawless tooth. In FIG. 1 all the right flanks are sanded, it is sufficient when, e.g. on the ring bearing 1 on the ring wheel 1, the ring wheel, by means of a suitable device, defines an angle such that all the left tooth flanks are now machined by the circumference of the abrasive disk. This explanation assumes, for the sake of a better understanding, that the abrasive disc does not wear and therefore must not be reset and in such a review always processes the entire tooth flank. In practice, of course, this is not so; un-10 where the last workflow, with virtually no chips decreases anymore, the grinding wheel must have a very precise diameter. In addition, the grinding wheel naturally removes the required chip in a majority of passes. Similarly, a rearward adjustment of the grinding wheel radially outward with respect to the ring wheel is necessary. These methods, which depend on the abrasive technique, are not to be further elucidated here, since they do not contribute to a better understanding of the invention.

For grinding such a ring wheel it can be used in FIG. 2-4 schematically illustrated apparatus. In this connection, it should be noted once again that FIG. 2-4 alone, the apparatus shows schematically, and no constructive design, which is of course substantially more complicated.

The apparatus has a base 10 which, in a central guide 11, carries a lower portion 12a 25 rotatably mounted around an axis Z of an eccentric shaft 12. The eccentricity of the two parts 12a and 12b of the eccentric shaft 12 is equal to its length with radius rR or rR1 of the rolling circle R, respectively R ', reduced the radius rF of the basic circle F, e.g. equal to rR. On the hypocycloid H, then the axis 30 of the abrasive body 7 is moved relative to the abrasive ring wheel 1. On the upper part 12b of the eccentric shaft 12 a disc 13. Non-pivotally disposed is mounted on the disc 13 two pivots 14 and 15 pivotally. These two drives do not simply interfere with each other. The drive located closest to the eccentric shaft is engaged by a tooth 16 arranged on the bearing bush 11 35 of the base 10, while the drive 15, which is located further away from the eccentric shaft, is also engaged with a tooth 17 fixedly connected to the clamping table 18. The clamping table 18 is pivotally mounted on it. FIG. 2 the upper part of the eccentric shaft 12. Tooth 17 is concentric to the upper part of the eccentric shaft.

142757 9

For drive of the device, a wheel 19 which is rotatable in a bearing bush 11 and which is rotated by a motor 20 as indicated by dashed lines. Into this gear 19 the shafts of the two gears 14 and 15 protrude so that, with rotation of the gear 19, it rotates with respect to the base 10 eccentric part 12b of the eccentric shaft 12 with the same speed with which the gear 19 is turned. The ratio of the ratio of the tooth 16 to the tooth 17 is chosen such that the rpm of the table 18 relates 10 to the rpm of the eccentric shaft 12 as the base circle diameter reduced by the roll circle diameter relates to the diameter of the base circle. Below, the two directions of rotation are the same. Thus, eg. the ring sprocket 1 not shown on the table has 21 teeth and the hypo-15 cycloid must be quadrupled (the hypocycloid H

first close again after four turns of the rolling circle in the basic circle), then the rpm of the table 18 relative to the rpm of the eccentric shaft 12 must be 4:21 at the same direction of rotation, and 17:21 at the opposite direction of rotation 20, respectively. Fitted to the base 10 there is a support device 21 for the abrasive spindle 22 rotatable about the shaft 22a, which carries the cylindrical abrasive body 7. In the illustrated embodiment, the abrasive spindle is not shown slidable. The drive is effected by means of a motor 23. Of course, in practice 25 the device must have a device for the abrasive spindle 22 in FIG. 2 in the drawing plane can be adjusted to the right and left to tighten the grinding spindle with increasing chip removal. Likewise, in practice, the device must have a device which moves the grinding spindle oscillating outwardly in and out of its axis in order for the tooth to become, precisely cylindrical.

Now engaged with continuous abrasive spindle 22 driven 20, the device shown undergoes the ring wheel 1, which is to be abraded 'relative to the abrasive spindle axis 22, a relative movement which precisely allows the abrasive spindle axis to travel with respect to the annulus 1 along the hypocycloid H. However, it is also possible to manufacture embodiments of the apparatus, in which e.g. the ring wheel 1 is stationary and the grinding spindle performs a corresponding movement. However, this becomes more complicated. Crucial to the present invention is that with the help of eccentric structures, it is possible to superimpose a slow pivotal motion with a fast pivotal motion about a small radius, thereby enabling the production of a hypocycloid movement.

Of course, for serial production, an apparatus of the kind just described can be provided with a rigid eccentric shaft and with an invariable transmission device.

If you want to grind different tooth numbers and different ring wheels with a single machine, in practice it is convenient to choose a different device. In this case, e.g. 2, the lower part of the eccentric shaft 12 in a corresponding rail mounted on the upper part of the eccentric shaft 13 is slidably mounted so that the eccentricity of the eccentric shaft is variable. Likewise, in such a case, the eccentric shaft and the table drive advantageously takes place by means of a shifting gear, which on the one hand drives the eccentric shaft separately and on the other table 18, so that the ratio of turnover can also be chosen. Such a gear change can - for the sake of a hint only - of one hand drive the gear 19, which is then immediately rigidly connected to the rail corresponding to the disc 13. With another drive of the gearshift, then by means of a concentric, geared to the lower part of the eccentric shaft, a corresponding toothing of the table 18 can co-operate, which toothing may, for example, be located as an internal toothing of the table 18. Here you can find there are many options.

Claims (3)

A method of grinding tooth flanks (1a, 1b) on an internally toothed sprocket (1), whereby the tooth flanks are abraded while rotating the internally toothed sprocket 5 about its axis (A) at a predetermined speed, and the axis of the internally toothed sprocket. at the same time rotate at a different speed about another axis (2) which is parallel to the axis of the internally toothed gear and has a distance (rR) from it equal to radius (rF) 10 of a basic circle (F) minus the radius (rR; rR ') of a rolling circle (R; R') which, when unrolling on the inside of the base circle, produces a cycloid, characterized in that the ratio of the speed of the internally toothed sprocket about its axis to the speed of the interior 15 toothed gears about its axis and the rpm of the internally toothed gears about said second axis is equal to the ratio of said distance to radius of the basic circle, that the ratio of radius for the rolling circle and radius for the basic circle can be expressed as a shortened fraction, 20 that the denominator in this fraction is equal to the number of teeth in the internally toothed gear and that the counter in the fraction is at least two and at most equal to the number of teeth in the internally toothed gear minus two . Method according to claim 1, characterized in that all the teeth are first ground on one tooth and then all the teeth are sanded on the other tooth in the same way. Apparatus for carrying out the method according to claim 1 or 2, with a base (10), an eccentric axis (12), which together has two shaft parts (12a, 12b) which run parallel but eccentrically in relation to to each other, the first (12a) of the two shaft parts being pivotally mounted in the base (10) with a pivotable table (18) mounted on the second shaft part on which the internally toothed gear (1) to be ground can up-