Bevel gear having modified geometry

Abstract

Bevel gear having a main body comprises a heel-side skin surface. The bevel gear has at least one tooth gap, which exits from the main body in the region of the skin surface. The tooth gap has a tooth base, the profile of which is defined by a base cone angle in relation to the workpiece axis of rotation. A concentric circumferential ring structure is provided on the skin surface, which is raised in relation to the skin surface, and which results in a heel-side exit angle between the tooth base and the ring structure, which is in the range between 125° and 160°.

Claims

1. A bevel gear having a main body comprising a heel-side, ring-shaped skin surface arranged concentrically in relation to a workpiece axis of rotation of the bevel gear, wherein the bevel gear has at least one tooth gap, which exits from the main body in the region of the skin surface, the tooth gap has a tooth base, the profile of which is defined by a base cone angle in relation to the workpiece axis of rotation, and a concentric circumferential ring structure is provided on the skin surface, which is raised in relation to the skin surface, and which results in a heel-side exit angle between the tooth base and the ring structure in the range between 125° and 160°.

2. The bevel gear according to claim 1, wherein the circumferential ring structure comprises at least one first ring surface and one second ring surface and the ring structure has a triangular shape in an axial section through the bevel gear, or comprises at least one first ring surface, one second ring surface, and one third ring surface, and the ring structure has a trapezoidal shape in an axial section through the bevel gear, or has an edge-free configuration and has a convex shape in an axial section through the bevel gear.

3. The bevel gear according to claim 1, wherein, by way of the circumferential ring structure having the exit angle, in a heel-side exit region of the tooth gap, an effective heel cone angle is predefined and is less than the heel cone angle of the heel truncated cone.

4. The bevel gear according to claim 1, wherein the circumferential ring structure further comprises a first ring surface, which is part of a truncated cone, is arranged concentrically in relation to the workpiece axis of rotation, and has an effective heel cone angle that is less than the heel cone angle.

5. The bevel gear according to claim 1, wherein the heel-side, ring-shaped skin surface is part of a heel truncated cone skin surface of a heel truncated cone.

6. The bevel gear according to claim 5, further comprising, in addition to the heel truncated cone, at least one head truncated cone arranged concentrically in relation to the workpiece axis of rotation, wherein the head truncated cone has a ring-shaped head truncated cone skin surface, the head truncated cone is defined by a head cone angle in relation to the workpiece axis of rotation, which is between 0° and 90°, and the heel truncated cone is defined by a heel cone angle in relation to the workpiece axis of rotation, which is between 0° and 90°.

7. The bevel gear according to claim 5, wherein the heel truncated cone is defined by a heel cone angle in relation to the workpiece axis of rotation, which is between 0° and 90°.

8. A method for producing a bevel gear comprising the following steps: producing a bevel gear having a main body comprising a heel-side, ring-shaped skin surface arranged concentrically in relation to a workpiece axis of rotation of the bevel gear, said producing comprising: providing a bevel gear blank; carrying out turning machining of the bevel gear blank, wherein, in the scope of this turning machining, a concentric circumferential ring structure is provided on the ring-shaped skin surface, wherein the concentric circumferential ring structure is (i) arranged concentrically in relation to the workpiece axis of rotation of the bevel gear, (ii) raised in relation to the skin surface and (iii) results in a heel-side exit angle between the tooth base and the ring structure in the range between 125° and 160°; and carrying out gear chip producing machining of the bevel gear blank, to form at least one tooth gap on the bevel gear, wherein the at least one tooth gap exits from the main body in the region of the skin surface and has a tooth base, the profile of which is defined by a base cone angle in relation to the workpiece axis of rotation.

9. The method according to claim 8, further comprising carrying out deburring machining of the bevel gear, wherein no deburring machining is carried out on the tooth base in the region of the heel-side skin surface.

10. The bevel gear according to claim 1, wherein the heel-side exit angle is in the range between 135° and 150°.

11. The bevel gear according to claim 10, wherein the circumferential ring structure comprises at least one first ring surface and one second ring surface and the ring structure has a triangular shape in an axial section through the bevel gear, or comprises at least one first ring surface, one second ring surface, and one third ring surface, and the ring structure has a trapezoidal shape in an axial section through the bevel gear, or has an edge-free configuration and has a convex shape in an axial section through the bevel gear.

12. The bevel gear according to claim 10, wherein, by way of the circumferential ring structure having the exit angle, in a heel-side exit region of the tooth gap, an effective heel cone angle is predefined and is less than the heel cone angle of the heel truncated cone.

13. The bevel gear according to claim 10, wherein the circumferential ring structure further comprises a first ring surface, which is part of a truncated cone, is arranged concentrically in relation to the workpiece axis of rotation, and has an effective heel cone angle that is less than the heel cone angle.

14. The bevel gear according to claim 10, wherein the heel-side, ring-shaped skin surface is part of a heel truncated cone skin surface of a heel truncated cone.

15. The bevel gear according to claim 14, further comprising, in addition to the heel truncated cone, at least one head truncated cone arranged concentrically in relation to the workpiece axis of rotation, wherein the head truncated cone has a ring-shaped head truncated cone skin surface, the head truncated cone is defined by a head cone angle in relation to the workpiece axis of rotation, which is between 0° and 90°, and the heel truncated cone is defined by a heel cone angle in relation to the workpiece axis of rotation, which is between 0° and 90°.

16. The bevel gear according to claim 14, wherein the heel truncated cone is defined by a heel cone angle in relation to the workpiece axis of rotation, which is between 0° and 90°.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the invention will be described in greater detail hereafter with reference to the drawings.

(2) FIG. 1A is a schematic side view of a bevel gear pinion;

(3) FIG. 1B is a schematic side view of the main body of the bevel gear pinion from FIG. 1A, wherein the exit of a single tooth gap in the region of the heel is indicated;

(4) FIG. 2 is a schematic sectional view (axial section) of a further bevel gear pinion, which is used for defining various terms;

(5) FIG. 3 is a schematic perspective view of a part of a further bevel gear, which only has one tooth gap here, wherein a burr has formed during the gear cutting in the base region on the heel and on the concave tooth flank;

(6) FIG. 4 is a schematic sectional view through a clamping device having a chucked bevel gear pinion;

(7) FIG. 5 is a schematic perspective view of a part of a first bevel gear according to the invention, which only has one tooth gap here, wherein the bevel gear comprises a circumferential ring structure on the heel;

(8) FIG. 6A is a schematic sectional view of a part of a further bevel gear pinion of the invention, wherein details of an exemplary circumferential ring structure are visible in section;

(9) FIG. 6B is an enlarged detail from FIG. 6A;

(10) FIG. 7 is a schematic side view of a further bevel gear of the invention having circumferential ring structure, wherein a single tooth gap is indicated;

(11) FIG. 8 is a schematic side view of a further bevel gear of the invention having circumferential ring structure, wherein two teeth and one tooth gap are shown; and

(12) FIG. 9 is a schematic flow chart having the steps of an exemplary method according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(13) Terms are used in conjunction with the present description which are also used in relevant publications and patents. However, it is to be noted that the use of these terms is only for better understanding. The inventive ideas and the scope of protection of the claims for protection are not to be restricted in the interpretation by the specific selection of the terms. The invention may readily be transferred to other term systems and/or technical fields. The terms are to be applied accordingly in other technical fields.

(14) The invention may be applied in general to bevel gears 31, wherein crown gears are also to be included in the present context. In a crown gear, the gear teeth are applied to the circular end face of a cylinder.

(15) The invention may be applied to bevel gears 31 having constant and varying tooth height h. The invention may also be applied to bevel gears 31 independently of the profile of the flank longitudinal line. The invention may thus be applied to straight-toothed bevel gears 31, helical-toothed bevel gears 31, and spiral-toothed bevel gears 31.

(16) The shape of a bevel gear 31 is defined by various specifications. These may include, among others, the desired transmission ratio, the modulus, the carrying capacity, and the overlap. In addition, however, the rigidity or deflection, the mounting, and the installation dimensions in the installed state play a role. In addition to the macro-geometry of the actual gear teeth of the bevel gears, the shape of the main body (main geometry), in particular in the matters of deflection, mounting, and producibility, also plays a role.

(17) FIG. 5 shows a first bevel gear 31 of the invention in a simplified view. The bevel gear 31 comprises a main body, which results from a head truncated cone KK and a heel truncated cone FK (as shown, for example, in FIG. 1B in the side view or in FIG. 2 in axial section). The head truncated cone KK and the heel truncated cone FK are arranged concentrically in relation to the workpiece axis of rotation R1. The head truncated cone KK has a ring-shaped head truncated cone skin surface and the heel truncated cone FK has a ring-shaped heel truncated cone skin surface. This ring-shaped heel truncated cone skin surface is identified here as the heel-side skin surface 65. In FIG. 5, the head truncated cone KK extends to the left from the point P1 and the heel truncated cone FK is located below the point P1.

(18) The head truncated cone KK is defined by a head cone angle δ.sub.a in relation to the workpiece axis of rotation R1 and the heel truncated cone FK is defined by a heel cone angle δ.sub.v in relation to the workpiece axis of rotation R1, as specified in the cited DIN standard and as shown in FIG. 2.

(19) In a bevel gear, the head cone angle δ.sub.a is between 0° and 90° and the heel cone angle δ.sub.v is between 0° and 90°. It is to be mentioned here that the heel truncated cone FK “mutates” into a cylinder in the case of a heel cone angle of 0° and into a flat ring surface or circular surface in the case of 90°. The invention may also be applicable for these special cases. Therefore, where necessary, a ring-shaped skin surface 65 is mentioned. This ring-shaped skin surface 65 is located concentrically in relation to the workpiece axis of rotation R1. The ring-shaped skin surface 65 can be part of a cylinder skin surface or part of the mentioned heel cone skin surface in some embodiments.

(20) Furthermore, the bevel gear 31 has at least one tooth gap 67 in the region of the head truncated cone skin surface, as shown in FIG. 5. This tooth gap 67 penetrates the head cone skin surface 65, or the tooth gap 67 exits out of the material of the main body of the bevel gear 31 in the region of the base cone skin surface 65, respectively. The tooth gap 67 has a tooth base 68, the profile of which is defined by the base cone angle δ.sub.f in relation to the workpiece axis of rotation R1 (see FIG. 2). The base cone angle δ.sub.f can be identical to the head cone angle δ.sub.a (if the tooth gap 67 has a constant tooth height h). However, in FIG. 2, the base cone angle δ.sub.f is not equal to the head cone angle δ.sub.a, and the base cone angle δ.sub.f is less than the head cone angle δ.sub.a.

(21) According to the invention, in some embodiment, the bevel gear 31 has a circumferential ring structure 80, which is raised in relation to the heel cone skin surface 65, on the heel truncated cone FK. FIG. 5 shows a first example of a circumferential ring structure 80. The circumferential ring structure 80 defines a heel-side exit angle δ.sub.1, which is in the angle range between 125° and 160°.

(22) Reference is made hereafter to FIGS. 6A and 6B, to be able to explain details of the invention more precisely. FIG. 6A shows a detail of an axial section through a further bevel gear 31 of the invention. The view of a right tooth flank 69 of a tooth is shown on the right in FIG. 6A. The tooth gap 67 is located in front of the tooth flank 69 in the view shown. FIG. 6B is an enlarged detail of FIG. 6A. The intersection line of the heel cone skin surface 65 with the plane of the drawing is shown on the basis of a dashed auxiliary line 61. The auxiliary line 66 is the intersection line of the base cone with the plane of the drawing. A parallel line to the workpiece axis of rotation R1 is shown by the reference sign R1∥.

(23) The circumferential ring structure 80, which has an exemplary triangle shape in the section shown, is in the region of the heel-side skin surface 65. It can be seen in the enlarged illustration of FIG. 6B that the ring structure 80 begins immediately in the region of the tooth base 68. The ring structure 80 has a triangular shape having two ring surfaces 81 and 82 in axial section here, if one considers the three-dimensional main body of the bevel gear 31. The exit angle δ can be determined from the base cone angle δ.sub.f and the rear cone angle δ.sub.v as follows (see FIG. 6A):
δ=180−δ.sub.f−δ.sub.v  (1)

(24) The first ring surface 81 now defines an effective heel cone angle δ.sub.ve, as shown in FIG. 6A. Because the heel cone angle δ.sub.ve is less than the rear cone angle δ.sub.v, a heel-side exit angle δ.sub.1 results, which is greater than the exit angle δ in previous bevel gears. This aspect of the invention can be inferred particularly clearly from FIG. 6B.

(25) This exit angle δ.sub.1, as already mentioned, may be in the angle range between 125° and 160° in some embodiments. By specifying an enlarged exit angle δ in relation to conventional bevel gears, the formation of a heel-side burr 70 is prevented during the gear cutting.

(26) The geometry of the heel truncated cone FK is not arbitrarily selectable. Inter alia, it is important, for the rolling of a bevel gear pinion without problems using a crown wheel, which the teeth of the crown wheel can mesh without collision with the tooth gaps of the bevel gear pinion on the heel side on the bevel gear pinion. The location and shape of the heel truncated cone may therefore be selected so that a distance exists between tooth base and tooth head of the counter wheel, the so-called head-base clearance. This is to be approximately constant over the tooth width if possible. Teeth also have a base rounding to reduce the tension concentration in the tooth base, no contact can also occur between this tooth rounding and the head edge of the counter wheel under the various operating conditions. However, the distance cannot be excessively large, to prevent an unnecessary increase of the tooth base tensions, due to a greater lever arm of the force on the tooth engagement and the tooth base.

(27) The ring structure 80 can also have a trapezoid shape viewed in an axial section in some embodiments, as shown in FIG. 8. A ring structure 80 in trapezoidal shape can be composed, for example, of three ring surfaces 81, 82, and 83.

(28) Due to the circumferential ring structure 80 of the invention, in some embodiments, an effective heel cone angle δ.sub.ve, which is less than the heel cone angle δ.sub.v of the heel truncated cone FK, results in the heel-side exit region of the tooth gap 67.

(29) The invention may be applied to bevel gears 31, which have a distance a.sub.2 of the outer head cone edge P1 to the installation surface 64 on the heel truncated cone FK, which is sufficiently large that the tooth base 68 exits in the region of the inclined skin surface (also referred to as the heel-side skin surface 65) of the heel truncated cone FK. In other words, it can be stated that the axial component a.sub.1 of the heel-side tooth height h.sub.e may be shorter than the distance a.sub.2, as shown in FIG. 2.

(30) The circumferential ring structure 80 of the invention has an upper circular edge 84, which is located at the exit of the tooth base 68 through the skin surface 65. In FIG. 5, this circular edge 84 is located a short distance above the exit of the tooth base 68 through the skin surface 65. In FIG. 7 and FIG. 8, the circular edge 84 is located in each case at the exit of the tooth base 68. In the positioning of the circumferential ring structure 80, the manufacturing tolerances are to be considered, so that in each case the exit of the tooth base 68 through the skin surface 65 is located in the circumferential ring structure 80.

(31) Bevel gears 31 of the invention have a circumferential ring structure 80, which comprises a first ring surface 81, which forms a part of a further truncated cone. This further truncated cone is arranged concentrically in relation to the workpiece axis of rotation R1 and it has an effective heel cone angle δ.sub.ve, which is less than the heel cone angle δ.sub.v.

(32) FIG. 7 shows a schematic side view of a further bevel gear 31 of the invention having circumferential ring structure 80. The profile of a tooth gap 67 is shown, which extends in the region of the head truncated cone skin surface of the head cone KK. Where the tooth base 68 of the tooth gap 67 penetrates the heel truncated cone skin surface of the heel truncated cone FK, the ring structure 80 is seated on the heel truncated cone FK. FIG. 7 shows an embodiment in which the ring structure 80 can again be approximated by a triangle. Two ring surfaces 81, 82 of the corresponding triangle are visible in FIG. 7.

(33) FIG. 8 shows a schematic side view of a part of a further bevel gear 31 of the invention having circumferential ring structure 80. The profile of a tooth gap 67 is shown, which is laterally delimited and/or defined by two teeth 75. The tooth gap 67 extends in the region of the head truncated cone skin surface of the head cone KK. Where the tooth base 68 of the tooth gap 67 penetrates the heel truncated cone skin surface of the heel truncated cone FK, the ring structure 80 is seated on the heel truncated cone FK. FIG. 8 shows an embodiment in which the ring structure 80 can be approximated by a trapezoid. Three ring surfaces 81, 82, 83 of the corresponding trapezoid are visible in FIG. 8. Shadings of the surfaces are applied in outline on the right in FIG. 8, to emphasize the location of the surfaces better.

(34) The ring structure 80 is preferably arranged on the heel truncated cone FK and dimensioned in some embodiments so that the distance a.sub.2 does not change in relation to a corresponding conventional bevel gear. The installation position thus remains the same and the formation of heel-side burrs 70 on the tooth base 68 is nonetheless prevented during the gear cutting.

(35) FIG. 9 shows a schematic flow chart of an exemplary production method of the invention. In a first step S1, a blank is provided, which is suitable for producing a bevel gear 31. For example, such a blank can have the shape of the main body 60 of FIG. 1B. This blank is now subjected in step S2 to turning machining, as is typical in the case of bevel gears. In this case, for example, the end faces can be turned to be planar. In addition, the ring structure 80 is created by turning machining. The position of the ring structure can be ascertained by a computer after the bevel gear 31 has been designed. In order that sufficient material is provided on the blank for the formation of the ring structure 80 by means of turning machining, a correspondingly enlarged or differently dimensioned heel cone FK is predefined.

(36) After the ring structure 80 has been created or worked out, the gear cutting S3 (the production of the tooth gaps) follows according to a known method. In this case, burrs can form on the heel side (i.e., in the region of the heel truncated cone), wherein the burrs can only form at the exit edges of the tooth flanks according to the invention. No burr formation occurs on the tooth base. In the following step, the deburring S4 can be carried out in the gear cutting machine or in another machine, wherein no heel-side burrs 70 are to be deburred here. The deburring S4 is therefore less time-consuming and less costly than in the case of conventional bevel gears.

LIST OF REFERENCE SIGNS

(37) TABLE-US-00001 bevel gear 31 shaft 32 workpiece spindle 33 body 60 rear cone 61 head cone 62 index cone 63 installation surface/end face/heel 64 heel-side rear surface/ring-shaped skin 65 surface base cone 66 tooth gap 67 tooth base (root) 68 tooth flank 69 burr 70 cover surface of KK 71 main surface of KK 72 cover surface of FK 73 main surface of FK 74 teeth 75 circumferential ring structure 80 first ring surface 81 second ring surface 82 third ring surface 83 upper circular edge 84 axial component of the heel-side tooth height a.sub.1 distance of outer head cone edge to the a.sub.2 installation surface tooth width b base circle diameter d.sub.fe first base circle diameter d.sub.f1 head cone angle δ.sub.a base cone angle δ.sub.f heel cone angle/rear cone angle δ.sub.v effective heel cone angle δ.sub.ve exit angle (without ring structure 80) δ exit angle δ.sub.1 angle of the heel edge δ.sub.2 heel truncated cone FK heel cone tip FKs tooth height h heel-side tooth height h.sub.e head truncated cone KK head cone tip KKs workpiece axis R1 parallel to the workpiece axis R1∥ transition region P outer head cone edge P1 rear cone length/heel cone length r.sub.v method steps S1, S2, S3, S4 critical region X