Hob peeling method and cutting tool for producing at least partially rounded tooth tips

Abstract

A method for providing teeth on working gears by cutting, wherein the working gear and the cutting tool are driven in rotation at a predetermined speed ratio along axes oriented at an intersection angle. The flanks of the cutting teeth form edges having flank cutting sections arranged on the edges of a gap between two adjacent teeth and extend along a first contour line, and which as a result of an advance in the direction of the working gear engage in a cutting manner to produce teeth having a flank contour predetermined by the shape of the cutting edge. Each of the flank cutting sections is adjoined by a tip cutting section which extends along a second contour line in the region of the base of the cutting tooth gap, wherein the second contour line is curved such that at least partially rounded tooth tips are produced on the teeth.

Claims

1. A cutting tool for skiving a working gear, comprising: cutting teeth with tip cutting sections to cut tips into teeth of the working gear while the working gear is driven in rotation by a workpiece spindle about a workpiece spindle axis and the cutting tool is driven in rotation by a tool spindle about a tool spindle axis, the working gear and the cutting tool being driven at a predetermined speed ratio to one another, the workpiece spindle axis and the tool spindle axis are oriented at an axis intersection angle to one another; wherein tooth flanks of the cutting teeth have, on first ends thereof, cutting edges having flank cutting sections, which are arranged on edges of cutting tooth gaps between two adjacent cutting teeth and in each case extend along first contour lines of each cutting tooth; wherein as a result of an advance in the direction of the rotation of the working pear, the flank cutting sections engage in the working gear in a cutting manner to produce the teeth, the teeth having a tooth flank contour predetermined by the shape of the cutting edges along the first contour lines of each cutting tooth; wherein each cutting tooth of the cutting teeth has an acute tooth flank of the tooth flanks, each acute tooth flank running at an acute angle to a front face of the associated cutting tooth; wherein each acute tooth flank has on the first end thereof a first flank cutting section of the flank cutting sections, each first flank cutting section being formed by an edge of a respective chamfer; wherein each cutting tooth of the cutting teeth further has an obtuse tooth flank of the tooth flanks, each obtuse tooth flank running at an obtuse angle to the front face of the associated cutting tooth; wherein each obtuse tooth flank has on the first end thereof a second flank cutting section of the flank cutting sections, each second flank cutting section being formed by an edge of a respective groove; wherein the front faces of all of the cutting teeth are located in a plane of a front face of the cutting tool, the front face of the cutting tool running around the tool spindle axis in a rotationally symmetrical manner; wherein for each cutting tooth of the cutting teeth, the first flank cutting section and the second flank cutting section thereof form a pair of flank cutting sections, and each pair of flank cutting sections is adjoined to a next pair of flank cutting sections by one of the tip cutting sections, which extend along a second contour line in an area of a base of one of the cutting tooth gaps; wherein the second contour line is curved with a corner curvature to produce at least partially rounded tooth tips of the teeth of the working gear with the tip cutting sections; and wherein the pair of flank cutting sections of each cutting tooth are offset by a distance from the plane of the front face of the cutting tool, whereas the tip cutting sections of each cutting tooth gap run in the plane of the front face of the cutting tool.

2. The cutting tool according to claim 1, wherein the one of the tip cutting sections connects the one pair of flank cutting sections to the next pair of flank cutting sections without a kink, except for a chip-breaking discontinuity, thereby creating a smooth transition from one of the first and second flank cutting sections of the one pair of flank cutting sections to a U-shaped cutting edge.

3. The cutting tool according to claim 1, wherein each of the tip cutting sections has a respective apex cutting section line of the cutting teeth, which runs in the plane of the front face of the cutting tool.

4. The cutting tool according to claim 1, wherein the one of the tip cutting sections comprises a first tip cutting section that follows the first flank cutting section of the one pair of flank cutting sections and further comprises a second tip cutting section that follows the second tip cutting section of the next pair of flank cutting sections.

5. The cutting tool according to claim 4, wherein the first and second tip cutting sections of the one of the tip cutting sections run in an arc that is oriented away from each of a first flank cutting section arc on which the followed first flank cutting section runs and a second flank cutting section arc on which the followed second flank cutting section runs.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the invention will be discussed below by means of enclosed drawings.

(2) FIG. 1 shows a working gear 1 and a cutting wheel, the teeth of which engage in the working gear 1 in a chip removing manner and which is formed by a cutting tool 2,

(3) FIG. 2 shows a further side view in viewing direction of the arrow II in FIG. 1 to clarify the axis intersection angle α,

(4) FIG. 3 shows a top view onto the arrangement illustrated in FIGS. 1 and 2,

(5) FIG. 4 shows a perspective illustration of the cutting tool 2 with a view onto the front face 7,

(6) FIG. 5 shows the section V in FIG. 4, greatly enlarged,

(7) FIG. 6 shows the section VI in FIG. 6, greatly enlarged,

(8) FIG. 7 shows a front face view of the cutting tool 2,

(9) FIG. 8 shows the section according to line VIII-VIII in FIG. 7,

(10) FIG. 9 shows the section IX in FIG. 7, greatly enlarged,

(11) FIG. 10 shows the section X in FIG. 8, greatly enlarged,

(12) FIG. 11 shows a second exemplary embodiment of the invention, similar to the illustration according to FIG. 6,

(13) FIG. 12 shows the section according to line XII-XII in FIG. 11,

(14) FIG. 13 shows a third exemplary embodiment of the invention in an illustration according to FIG. 3,

(15) FIG. 14 shows the section according to line XIV-XIV in FIG. 13 through the workpiece spindle axis 4 and the point of the lowest engagement of a cutting tool in the tooth gap to be produced,

(16) FIG. 15 shows the section according to tine XV-XV in a sectional plane, which runs perpendicular to the sectional plane of the section according to line XIV-XIV,

(17) FIG. 16 shows the top view onto the front face having the cutting edges of the cutting wheel 2 illustrated in FIGS. 13 to 15,

(18) FIG. 17 shows a side view onto the cutting wheel illustrated in FIG. 16,

(19) FIG. 18 shows a rear side view onto the cutting wheel illustrated in FIG. 16,

(20) FIG. 19 shows the cutting wheel illustrated in FIGS. 16 to 18 in a perspective view,

(21) FIG. 20 shows a fourth exemplary embodiment according to FIG. 14,

(22) FIG. 21 shows a cutting wheel comprising a widened cutting tooth 24 as fifth exemplary embodiment of the invention, and

(23) FIG. 22 shows the side view of the cutting wheel illustrated in FIG. 21.

DETAILED DESCRIPTION

(24) The method according to the invention is carried out by means of a machine tool known in the prior art. This machine tool is not illustrated in the drawings, because it is described in a variety of forms in other publications. Reference is made only in an exemplary manner to a device, as it is described in DE 4 122 460 C1, DE 101 13 653 A1 or DE 10 2005 049 530 B4.

(25) A tool spindle, which driven in rotation about a tool spindle axis 5, supports a cutting tool 2, which has cutting teeth 3, which protrude radially to the outside. The apex lines of the cutting teeth 3 run obliquely to the tool spindle axis 5, which coincides with the contour axis of the cutting tool 2. Cutting teeth gaps 20 are located between the cutting teeth 3. The front face 7 of the cutting tool 2 is located in a plane, which runs perpendicular to the tool axis 5 or of the tool axis 5, respectively. On its edge adjoining the front face 7, a tooth flank 6, which runs at an acute angle to the front face 7, has a flank cutting section 12. On its edge adjoining the front face 7, a tooth flank 6′, which is located opposite this tooth flank 6 and which runs at an obtuse angle to the front face 7, has a flank cutting section 8 (see FIGS. 8, 10). The two flank cutting sections 8, 12 run on a line, which is curved in the plane of the front face 7 and which is curved in such a way that the tooth flanks 14 of teeth 13 of a working gear 1 obtain a predetermined involute form by means of these flank cutting sections 8 (see FIGS. 7, 9).

(26) The working gear 1 has an axis 4 and is driven in rotation by a non-illustrated workpiece spindle, which defines a workpiece spindle axis 4. The workpiece spindle axis 4 and the tool spindle axis 5 are oriented at a fixed axis intersection angle α to one another (see FIG. 2). As a result, the cutting tool 2, which is driven in rotation synchronously to the working gear 1, engages with its cutting teeth 3 in the working gear 1 in a peeling manner (see FIG. 3). By means of an advance, which is directed in the direction of extension of the teeth 13 of the working gear 1, the tooth gaps 17 are peeled out from between the teeth 13. Said tooth flanks 14, which run on an involute, are formed. The advance can also be directed in opposite direction of the peeling direction. The processing of the working gear 1 then takes place in a pulling step.

(27) In the case of the cutting tool 2, a tip cutting section 9 follows the flank section 8 and a tip cutting section 11 follows the flank cutting section 12 (see FIG. 5, 6, 9). The two tip cutting sections 9, 11 run on an arc-shaped line, wherein the arc, on which the tip cutting section 9, 11 runs, is oriented away from the arc, on which the flank cutting section 8, 12 runs. The two arcs are curved in opposite direction, but in the case of this exemplary embodiment are located in a common plane, which runs parallel to the front face 7, which, in turn, runs perpendicular to the tool spindle axis 5 or to the contour axis of the cutting tool 2, respectively.

(28) The cutting edge formed by the flank sections 8, 12, the apex cutting section 10 and the tip cutting sections 9, 11, extends from the tip of a cutting tooth 3 to the tip of an adjacent cutting tooth 3 in an interruption-free and smooth manner through the entire cutting tooth gap 20. In the case of the exemplary embodiment, the individual sections 8 to 12 of the cutting edge transition into one another in a kink-free manner. While the tooth flanks 14 are profiled by means of the flank cutting sections 8, 12, the tooth tip 16 of the tooth 13 is profiled by means of the tip cutting sections 9, 11 and the apex cutting section 10. The tooth tip 16 thus obtains a rounding, which is defined by the shape of the tip cutting sections 9, 11 and the shape of the apex cutting section 10. This can be a continuous rounding. However, the tip can also be only partially rounded.

(29) It can be gathered from the greatly enlarged illustrations of FIGS. 5, 6, 9 and 10 that a chamfer 18, which forms the flank cutting section 12 in the transition area to the tooth flank 6, forms the edge of the tooth flank 6 adjoining the front face 7 in an acute-angled manner. It can further be gathered from these figures that the tooth flank 6′, which adjoins the front face 7 with its edge in an obtuse-angled manner, forms a flank cutting section 8, which is formed by the edge of a groove 19, which extends along the edge in the front face 7. The groove 19 and the chamfer 18 can be created by means of the same grinding tool, a specifically trimmed grinding wheel. They are ground into the front face of the tool. In spite of tooth flanks 6, 6′, which run obliquely to the front face 7, flank cutting sections 8, 12 can be created, which have a defined cutting edge angle, by means of such a face sharpening.

(30) By forming a beveling 21, the two tip cutting sections 9, 11 transition into the front face 7. The beveling 21 can be ground into the tool. This occurs in such a way that the tip cutting sections 9, 11 transition into one another in the area of the apex section 10 and transition with their other ends into the respective flank cutting section 8, 12. A plane is thus formed, in which all cutting edges of the cutting tool 2, which are in each case formed by cutting sections 8 to 12, are located, wherein this plane runs at a parallel offset to the plane of the front face 7.

(31) In the case of the second exemplary embodiment illustrated in FIG. 11, each cutting tooth 3 or each cutting tooth gap 20, respectively, has two flank cutting sections 8, 12. The flank cutting section 8 is formed by the edge of a groove 19, and the flank cutting section 12 is formed by the edge of a chamfer 18. The flank cutting sections 8, 12 are thus located so as to be offset by a small distance to the front face 7. This distance is maximally the depth of the groove 19 or of the depth of the chamfer 18, respectively.

(32) There is no beveling 21 here. Here, the two tip cutting sections 9, 11 and the apex cutting section 10 located therebetween run in the plane of the front face 7. As a result, the flank cutting section 12 transitions into the tip cutting section 11 by forming a slight discontinuity 23, and the flank cutting section 8 transitions into the tip cutting section 9 by forming a slight discontinuity 22. These two discontinuities 22, 23 have the advantage that the chip breaks there in response to hob peeling. The desired short chips are created. It is avoided that chip curls form in the case of a circumferential, uninterrupted cutting edge.

(33) The discontinuities 22, 23, however, are so small that they do not leave behind any or only very slight contours in the workpiece.

(34) In the case of the third exemplary embodiment illustrated in FIGS. 13 to 19, a working gear 1, which is provided with teeth on the inside, is processed by means of a cutting tool 2, which is provided with teeth on the outside. FIG. 14 substantially corresponds to an illustration according to FIG. 1 of the first exemplary embodiment. While in the case of the first exemplary embodiment, the axis of rotation 4 of the working gear 1 and the axis of rotation 5 of the cutting wheel 2 run parallel to one another in a projection plane, in which the workpiece spindle axis 4 is located and which is placed through the lowest tooth engagement location of the cutting tooth, the tool spindle axis 2 has an inclination β with respect to the workpiece spindle axis 4 in the case of the exemplary embodiment illustrated in FIGS. 13 to 19. In the case of the exemplary embodiments illustrated in FIGS. 1 to 12, the apex lines of the cutting teeth 3 run on a truncated cone jacket surface. In the case of ht exemplary embodiment illustrated in FIGS. 13 to 19, the apex lines 3′ of the cutting teeth 3 run on a cylinder jacket surface. Due to the angle of inclination β, a clearance angle of the apex line 3′ of the tooth tips results across the extension length of the cutting teeth 3 as compared to the apex line of the tooth foot of the toothing, which is to be produced, in the working gear 1.

(35) FIG. 15 shows the axis intersection angle α. The axis intersection angle α, which is preferably approximately 20°, is measured in a plane, which extends perpendicular to the projection plane, in which the angle of inclination β is located, which is preferably 8°.

(36) Here, the cutting edges of the cutting teeth 3 are also formed by chamfers 18 or grooves 19, respectively, and have a tip cutting section.

(37) FIG. 20 shows a fourth exemplary embodiment in an illustration according to FIG. 14. In contrast to the third exemplary embodiment, the front face 7 is not located in a plane, but in an inner cone surface, so that the cutting wheel 2 creates a the toothing in the working gear 1 with a positive rake angle.

(38) The teeth 3, 24 of the cutting wheel 2 illustrated in FIGS. 21 and 22 also form cutting edges, which are formed by grooves 19 or chamfers 18, respectively, and which have tip cutting sections. In contrast to the cutting tools 2 described in the preceding exemplary embodiments, the cutting tool illustrated in FIGS. 20 and 21 has at least one cutting tooth 24, which is widened in circumferential direction of the cutting tool 2. The cutting tooth 24 extends across a circumferential length of two cutting teeth 3 of the regular division. The block cutting tooth 24 is thus formed by two regular cutting teeth 3, between which the tooth gap is missing.

(39) The circumferential length of the block cutting tooth 24, however, is otherwise not limited. The tooth length in circumferential direction can also be an uneven division.

(40) The front face 7 of the working gear 1 can be a plane. The front face 7, however, can also be an inner cone surface. The apex lines of the cutting teeth 3, 24 can be arranged on a cylinder jacket surface, so that the cutting wheel 2 can be used in an operating position according to FIG. 14 or 20. The apex lines of the cutting teeth 3, 24, however, can also run on a truncated cone jacket surface, as in the case of a tool according to FIGS. 1 to 12.

(41) The above statements serve as an explanation of the inventions captured by the application as a whole, which further develop the prior art at least by means of the following feature combinations, in each case also independently, namely:

(42) A method, which is characterized in that the cutting edge 12, which is assigned to a tooth flank 6, which runs at an acute angle to the front face 7 of the cutting tooth 3, 24, is formed by the edge of a chamfer 18, the cutting edge 8, which is assigned to a tooth flank 6′, which runs at an obtuse angle to the front face 7 of the cutting tooth 3, is formed by the edge of a groove 19, and the front faces 7 of all cutting teeth 3, 24 are located in a surface, in particular a plane or an inner cone jacket surface, which runs around the tool spindle axis 5 in a rotationally symmetrical manner.

(43) A method, which is characterized in that each of the two flank cutting sections 8, 12 is adjoined by a tip cutting section 9, 11, which extends along a second contour line in the area of the base of the cutting tooth gap 20, wherein the second contour line is curved with a foot corner curvature and that at least partially rounded tooth tips 16 of the teeth 13 are produced by means of the tip cutting sections 9, 11.

(44) A method, which is characterized in that the rounded tip cutting sections 9, 10, 11 connect the two flank cutting sections 8, 12, except for a chip-breaking discontinuity, in a substantially kink-free manner to a U-shaped cutting edge.

(45) A method, which is characterized in that the apex line 3′ of the cutting teeth 3, 24, which runs in the direction of extension of the cutting teeth 3, 24, run in a cylinder jacket surface and that the tool spindle axis 5 is inclined by an angle of inclination β at right angles to the axis intersection angle α with respect to the workpiece spindle axis 4.

(46) A method, which is characterized in that the cutting tool 2 has at least one cutting tooth 24, which is widened in circumferential direction of the cutting tool 2 with respect to the other cutting teeth 3 and the speed ratio is chosen in such a way that the widened cutting tooth 24 enters into the same widened tooth gap between two teeth of the working gear 1 again, after rotating around the cutting tool 2 once or several times and after rotating around the working gear 1 once.

(47) A method, which is characterized in that the at least one widened cutting tooth 24 extends across at least one even or uneven or fractional number of sections of the regular division of the cutting tool 2 and/or across a complete tooth gap or has any length.

(48) A cutting tool, which is characterized in that the cutting edge 12, which is assigned to a tooth flank 6, which runs at an acute angle to the front face 7 of the cutting tooth 3, is formed by the edge of a chamfer 18, the cutting edge 8, which is assigned to a tooth flank 6′, which runs at an obtuse angle to the front face 7 of the cutting wheel 3, is formed by the edge of a groove 19, and the front faces 7 of all cutting teeth 3, 24 are located in a surface, in particular a plane or an inner cone jacket surface, which runs around the tool spindle axis 5 in a rotationally symmetrical manner.

(49) A cutting tool, which is characterized in that each of the two flank cutting sections 8, 12 is adjoined by a tip cutting section 9, 11, which extends along a second contour line in the area of the base of the cutting tooth gap 20, wherein the second contour line is curved with a foot corner curvature.

(50) A cutting tool, which is characterized in that the rounded tip cutting sections 9, 10, 11 connect the two flank cutting sections 8, 12 without a kink, except for a chip-breaking discontinuity, in a substantially kink-free manner to a U-shaped cutting edge.

(51) A cutting tool, which is characterized in that the apex line 3′ of the cutting teeth 3, 24, which runs in the direction of extension of the cutting teeth 3, 24, run in a cylinder jacket surface.

(52) A cutting tool, which is characterized in that the cutting tool 2 has at least one cutting tooth 24, which is widened in circumferential direction of the cutting tool 2 with respect to the other cutting teeth 3.

(53) A cutting tool, which is characterized in that the at least one widened cutting tooth 24 extends across at least one complete tooth gap extending across the regular division of the cutting tool.

(54) A method or a device, which are characterized in that each of the two flank cutting sections 8, 12 is adjoined by a tip cutting section 9, 11, which extends along a second contour line in the area of the base of the cutting tooth gap 20, wherein the second contour line is curved with a foot corner curvature, and that at least partially rounded tooth tips 16 of the teeth 13 are produced by means of the tip cutting sections 9, 11.

(55) A method or a device, which are characterized in that the cutting edge 12, which is assigned to a tooth flank 6, which runs at an acute angle to the front face 7 of the cutting tooth 3, is formed by the edge of a chamfer 18, the cutting edge 8, which is assigned to a tooth flank 6′, which runs at an obtuse angle to the front face 7 of the cutting tooth 3, is formed by the edge of a groove 19, and the cutting edges 9 to 12, which define a cutting tooth gap 20 between two adjoining cutting teeth 3, are offset maximally by the depth of the groove 19 or the depth of the chamfer 18 or in particular maximally by the difference of the depth of the chamfer 18 from the depth of the groove 19 with respect to a common plane.

(56) A use for providing teeth on working gears 1 by means of the hob peeling method.

(57) A device, which is characterized by an electronic control device, which is programmed in such a way that a working gear 1 is produced by means of hob peeling.

(58) All disclosed features (alone or also in combination with one another) are significant for the invention. The disclosure content of the corresponding/enclosed priority documents (copy of the prior application) is hereby also included in the disclosure of the application in its entirety, also for the purpose of adding features from these documents in the claims of the application at hand. The features of the subclaims characterize independent inventive further developments of the prior art, in particular in order to file divisional applications on the basis of these claims.