Method and device for producing undercuts and gearwheels

Abstract

The invention relates to a device and a method for producing a gearwheel, the method comprising: a first step, in which a toothing (5), comprising teeth (6) having tooth flanks (8), is produced by hob peeling; a second step, in which protuberances (11) are produced in the region between a tooth root (10) of the teeth (6) and a root-forming circle (9) by a machining process; and a third step, in which undercuts (12) are produced in the tooth flanks (8) only in one or more first portions (l1) of the width (B) of the toothing (5). In order to increase the stability of the teeth of the toothing, according to the invention the protuberances (11) extend only beyond second portions (l2) of the width (B) of the toothing (5), which second portions each have one overlapping region with the first portion (l1).

Description

Description Method and apparatus for manufacturing backings and gears field of technology

[0001] The invention relates to a method for manufacturing a gear with a first step in which a toothing having teeth with tooth flanks is produced, for example by a gear-cutting process, such as gear skiving, with a second step in which protuberances are produced in the area between a tooth root of the teeth and a root form circle by a chip-removing process, and with a third step in which backings are produced in the tooth flanks only in one or more first partial areas of the width of the gearing.

[0002] The invention also relates to a device for carrying out the process. State of the art

[0003] German patent DE 102005049528 describes a device and a method for manufacturing sliding sleeves. In a first process step, an internal tooth is produced by gear skiving in a ring-shaped workpiece. In partial areas of the width of the tooth flanks of the tooth thus produced, backings are incorporated. This is done with a backing tool.

[0004] The DE 10002188Albe describes a depositing tool that has cutting edges and is driven by a rotary axis that runs parallel to the rotary axis of the workpiece.

[0005] DE 10 2008 037514 Al describes the manufacturing of gear teeth using a gear skiving device.

[0006] Devices for rolling edge and the rolling peeling process are also described in WO 2012 / 152660 Al and EP 2537615 Al, the latter disclosing a rolling peeling process in which grooves can be locally incorporated into a toothing.

[0007] In gear skiving, the gear skiving wheel has a toothed structure that forms a multitude of cutting teeth, with each cutting tooth having two adjacent teeth on a face. During gear skiving, the gear skiving wheel engages with the gear teeth to be created on the workpiece, similar to a helical gear drive. The tool axis and the workpiece axis are skew to each other during gear skiving. If the gear skiving wheel is cylindrical, the tool axis must be slightly inclined away from the workpiece axis to create a kinematic clearance angle. This is not necessary when using a frustoconical gear skiving wheel. In this case, the common perpendicular of the two axes can pass through the point of contact between the tool and the workpiece. During gear skiving, the tool can be advanced in the width direction of the teeth. The chip removal occurs essentially in the axial direction of the tool.

[0008] Sliding sleeves, as used in motor vehicle transmissions, are formed by internally toothed gears in which the tooth flanks have recesses. These recesses are indentations extending over a portion of the width of the tooth flanks. The production of these recesses is carried out using a recessing tool, as described in the aforementioned DE 100 02188 A1. When the backing tool is used, the cutting teeth, which move along a cycloidal path, engage the tooth flank radially and with an azimuthal motion component. Due to the shape of the backing material and the trajectory of the cutting edge, unfavorable cutting conditions arise in the area of ​​the tooth flank near the tooth root. A protuberance, which is introduced into the area of ​​the tooth flank adjacent to the tooth root, removes material there, thus improving the cutting conditions. In the prior art, the protuberance extends over the entire width of the tooth, resulting in a weakening of the tooth. Summary of the invention

[0009] The invention is based on the objective of specifying measures that, on the one hand, improve the cutting conditions for incorporating the backings and, on the other hand, largely avoid weakening the tooth.

[0010] The problem is solved by the invention specified in the claims, wherein the dependent claims not only represent advantageous further developments of the invention specified in the subordinate claims, but are also independent solutions to the problem.

[0011] First and foremost, it is proposed that the protuberances, which reduce the material thickness of the tooth root, extend only over a portion of the width of the tooth flanks, namely only over a portion of the width in which the backings also extend. The width of the backings overlaps with the width of the protuberances. It is specifically proposed that a first portion of the width of the teeth incorporates the backings. This portion can be 10%, 20%, or 30% of the width of a tooth flank. The protuberance also extends only over a portion of the gear's width. This second portion can have the same width as the first portion, where the backing is located. However, it is sufficient if the two portions overlap, forming an overlap zone. Preferably, the gear is produced by gear skiving. The gear can be manufactured using known gear-making processes, particularly those involving rolling. Suitable processes include broaching, reaming, milling, especially gear hobbing, and, particularly preferably for rim gears, gear skiving. The protuberances can be produced using similar processes, especially gear skiving, gear hobbing, or gear shaping. Machining the tooth flank with an end mill is also an option.For the backing, methods as described in DE 103 29413 A1 or DE 10 2014 108438 A1 can be used. In this method, a backing tool with at least one cutting edge can be employed. In a preferred embodiment, not only the gear teeth are produced by gear skiving, but the protuberances are also manufactured using the gear skiving process. The gear skiving tool then engages the tooth flanks already machined in the first process step only in the second sub-area. According to a further development of the method, the contours of the cutting edges of the cutting teeth of the two gear skiving tools are different. The cutting edge of the gear skiving tool used to produce the gear teeth can have a section that machines the area of ​​the tooth flank adjacent to the tooth tip of the gear teeth.This root section of the cutting tooth has a greater thickness than the corresponding section of the cutting tooth of the second gear skiving tool, which is used to machine the protuberance. The root section of the cutting tooth of the second gear skiving tool is therefore thinner than that of the first gear skiving tool. It is recessed in the involute area to such an extent that no machining takes place there. This occurs during the machining of the protuberance. Thus, no chip removal occurs in the area of ​​the tooth of the workpiece near the tooth tip. Regarding the contour of the cutting edges in the area of ​​the section used to machine the area of ​​the tooth adjacent to the tooth root, the opposite is true. The section of the cutting tooth that produces the protuberances, i.e., the tip section there, is thicker than the corresponding section of the first tool used to produce the gear teeth. It can also be provided that the cutting tooth producing the protuberance has a greater height than the cutting tooth used to produce the gear teeth in the first step. With such a design, the protuberance can then extend not only over the area of ​​the tooth flank adjacent to the tooth root, but also over the tooth root itself. In a third process step, the backings are produced essentially according to the method described in DE 100 02 188 A1.While in the first two process steps, which are gear skiving steps, the axes of the rotating workpiece and the rotating tool are skew to each other, the two axes can run parallel to each other when producing the backings. The feed can be radial, relative to the workpiece. If the tooth flanks each have two backings, these two backings can be produced simultaneously. For this purpose, a rotating cutter head of the backing tool can have several cutting edges arranged one behind the other in the axial direction. The backing tool can be a gear-shaped tool. However, the backing tool can also have only one or a multitude of individual cutting edges. The backing tool can also be designed so that only one cutting edge is provided for each backing.

[0012] The device according to the invention is essentially a CNC machine with a plurality of axes. The machine can have a rotary-driven workpiece axis, a rotary-driven first tool axis that carries the gear-cutting tool for manufacturing the gear teeth, a rotary-driven second axis that carries the gear-cutting tool for manufacturing the protuberances, and a third rotary axis that carries the backing tool, which can be rotated about a rotary axis. The three tool axes can be positioned on or towards the workpiece by a control unit. They can be set into rotation by the control unit, synchronized with the rotation of the workpiece, which is also initiated by the control unit. Furthermore, they can also be advanced relative to the workpiece by the control unit. The control unit is programmed such that, during operation of the device, a gear is manufactured according to the process characteristics described above. Brief description of the drawings

[0013] An embodiment of the invention is explained below with reference to the attached drawings. These show: Fig. 1 shows a gear skiving device according to DE 10 2005 049528 Al, with which both in a first process step the gear teeth and in a second process step protuberances can be introduced into the gear teeth, in a sectional first view, Fig. 2 shows the tool / workpiece arrangement according to Figure 1 in a view rotated by 90 degrees. Fig. 3 shows a device for creating deposits as described in DE 100 02188 Al, with which in a third In the second step of the procedure, deposits are placed in the teeth at the points where the protuberances were created. Fig. 4 shows a view rotated by 90 degrees of the tool / workpiece arrangement shown in Figure 3. Fig. 5 shows a partial section through a tooth, where the reference numeral 11 denotes protuberances in the area of ​​a tooth root 10 that locally reduce the thickness of the tooth. Fig. 6 shows a view from the direction VI in Figure 5 onto a tooth flank 8 of a tooth 6, Fig. 7 shows a representation according to Figure 5, however after the protuberances 11 have been made and before the backings 12 have been made. Fig. 8 shows a representation with viewing direction VIII in Figure 7, Fig. 9 shows a view in direction IX in Figure 7 and Fig. 10 shows the course of a cutting edge 16 of a cutting tooth of a first gear skiving tool, with which the gear teeth are produced and a cutting edge 19 of a cutting tooth of a second gear skiving tool, with which the protuberance is produced. Description of the embodiments

[0014] Using a CNC machine tool with a multitude of motor-driven axes, in which a workpiece 1 to be internally geared is held in a chuck of a workpiece spindle, a gear tooth 5 is produced in the workpiece 1 by means of a first skiving tool 3, which is driven by a first tool axis, using a gear skiving process. In an embodiment not shown, externally toothed gears can also be provided with a gear tooth.

[0015] The tool axis 4 of the tool 3 is pivoted at an axis cross angle E relative to the workpiece axis 2 of the workpiece 1. When using a cylindrical tool 3, as is the case in the embodiment example, the tool axis 4 can additionally have an inclination angle q relative to the tool axis 2.

[0016] By synchronous rotation of workpiece 1 and tool 3 and a simultaneous axial feed movement, an internal toothing with a width B extending over the axial width of the workpiece 1 is produced in the workpiece 1.

[0017] Following this first process step, a second gear skiving tool 3', which is carried by the same or a second tool axis, is also used to introduce at least one protuberance 11 into the tooth flanks 8 of the gear 5 produced in the first process step, also using the gear skiving process. Figures 1 and 2 show both the first and second process steps. The second process step differs from the first process step, firstly, in the gear skiving tool used. The essential difference, however, is the only- Partial engagement of the second gear skiving tool into the tooth flanks 8 of the gearing 5.

[0018] After positioning the second tool 3', with its cutting edges brought into contact with the tooth 5 within its width, a radial feed is initially performed. During this feed, the cutting edges of the second cutting tool 3' engage the tooth flanks 5 to produce the protuberances 11 by removing material from the tooth flanks 5 in a region adjacent to the tooth root 10. The axial cross angle may already be sufficiently large to produce the protuberances 11 without further feed. However, the tool can also be moved a short distance axially, i.e., in the width direction of the tooth. The protuberances 11 then extend only over a partial area across the entire width B of the tooth flank 8 and over a height projecting from the tooth root 10 to a root profile 9.During the second step of the process, the tooth flank between the base circle 9 and the tooth head 7 is not machined.

[0019] The protuberances 11 thus produced extend over a portion of the tooth flank 8, spaced apart from the two end faces of the gear 1. The protuberances 11 can extend to the tooth root. However, they can also extend beyond this into the core area of ​​the workpiece 1.

[0020] Following this second process step, a third tool, a backing tool as shown in Figures 3 and 4, is used to cut backings 12 into the tooth flanks 8. The backings 12 are essentially worked into the tooth flanks 8 where the protuberances 11 were formed in the previous process step. have been produced. However, the length h of the protuberance 11, measured in the width of the tooth 6, can differ from the length h of the backing 12, which is also measured in the width of the tooth 6. In the embodiment shown in the drawings, the length h of the protuberance 11 is slightly less than the length h of the backing 12. In an embodiment not shown, however, the situation may be reversed. The two lengths h and h can also be the same.

[0021] It can be advantageous if the section of the backing 12 located between the tooth root 10 and the root circle 9 lies entirely within the region of a protuberance 11. It can therefore be provided, in particular, that the total width extent I2 of the backing 12 is greater than the width extent 11 of the protuberance 11, but that the width extent 11 of the protuberance 11 is greater than or at least equal to the width extent I2 of the backing 12 in the region between the root circle 9 and the tooth root 10, wherein the position of the root circle 9 can be defined by the radial distance of an edge of the protuberance 11 from the tooth root 10.

[0022] The backings 12 can extend over a greater height, relative to the tooth height hi, I12, than the protuberances 11. In the exemplary embodiment, the backings 12 do not extend into the area of ​​the tooth root 10. However, it can also be provided that the backings 12 extend into the area of ​​the tooth root 10 or beyond the area of ​​the tooth root 10 into the core area of ​​the workpiece 1.

[0023] Figure 10 shows, by way of example, the contours of the cutting edges 16 of a first gear skiving tool 3 and the cutting edges 19 of a second gear skiving tool 3' in a superimposed view. In the area 18, 21 of the cutting edges 16, 19, where the first gear skiving tool 3 forms the cutting edge 19 of the tooth head 7- The contour of the adjacent tooth flank 8 differs in that the section 18 of the first gear skiving tool 3, which processes the tooth flank 8 adjacent to the tooth head 7, is thicker than the corresponding section 21 of the second gear skiving tool 3'. The cutting tooth produced by the protuberances 11 thus does not process the tooth flanks 8.

[0024] The areas 17, 20 of the cutting edges 16, 19, which engage in machining on the workpiece 1 in the area of ​​the tooth root 10, differ in that the head section 20, which produces the protuberances 11, is thicker than the head section 17, which produces the flank area of ​​the tooth flanks 8 between the root form circle 9 and the tooth root 10 in the first process step.

[0025] The tooth flanks 8 can extend along an involute. The protuberances 11 can also extend along an involute, which, however, transitions into the area of ​​the tooth flank 8 between the tooth head 7 and the root circle 9 at the root circle by forming a kink. The protuberances 11, however, only extend essentially over the portion of the tooth width into which the backings 12 are also incorporated.

[0026] The foregoing statements serve to explain the inventions covered by the application as a whole, which each independently further develop the prior art at least through the following combinations of features, whereby two, several or all of these combinations of features may also be combined, namely:

[0027] A method characterized in that the protuberances 11 extend only over second sub-areas h of the width B of the toothing 5. cken, each of which has an overlap area with the first sub-area h.

[0028] A method characterized in that the gear teeth are produced by a rolling process, skiving, hobbing or broaching and / or that the protuberances 11 are produced by skiving, broaching, hobbing or with an end mill.

[0029] A method characterized in that the tooth flanks 8 are produced with a first tool, in particular a gear skiving tool 3, whose cutting edges 16 run along a first contour and the backings are produced with a second tool, in particular a gear skiving tool, whose cutting edges 19 run along a second contour different from the first contour.

[0030] A method characterized in that the section 18 of the cutting edges 16 of the first tool 3 adjacent to the tooth head 7 and machining the area of ​​the tooth flank 8 is thicker than the corresponding section 21 of the cutting edges 19 of the second tool 3' and in that the section 20 of the cutting edges 19 of the second tool 3' machining the protuberances 11 is thicker than the corresponding section 17 of the first tool 3.

[0031] A method characterized in that the height hi of the cutting teeth forming the cutting edges 16 of the first tool 3 is smaller than the height h? of the cutting teeth forming the cutting edges 19 of the second tool 3'.

[0032] A method characterized in that the backings 12 are produced by using a cutting edge tool with a chip-removing process.

[0033] A device characterized in that the control device 22 is configured such that, during operation of the device, a gear 1 is manufactured according to the method according to one of claims 1 to 6.

[0034] A device characterized in that the second tool 3' is a gear skiving tool, wherein the section 18 of the cutting edges 16 of the first tool 3 adjacent to the tooth head 7 and machining the area of ​​the tooth flank 8 is thicker than the corresponding section 21 of the cutting edges 19 of the second tool 3' and that the section 20 of the cutting edges 19 of the second tool 3' machining the protuberances 11 is thicker than the corresponding section 17 of the first tool 3.

[0035] A device characterized in that the third tool 13 is a cutting edge tool rotatable about a workpiece axis 2 parallel to a workpiece axis.

[0036] All disclosed features are essential to the invention (individually, but also in combination with one another). The disclosure of this application hereby incorporates in full the disclosure content of the associated / attached priority documents (copy of the earlier application), also for the purpose of including features of these documents in the claims of the present application. The dependent claims, even without the features of a referenced claim, characterize independent inventive developments of the prior art, in particular for the purpose of filing divisional applications on the basis of these claims. The [unclear text] The invention specified in each claim may additionally include one or more of the features described above, in particular those identified by reference numerals and / or listed in the reference numeral list. The invention also relates to designs in which individual features mentioned in the preceding description are not implemented, especially insofar as they are recognizably unnecessary for the respective purpose or can be replaced by other technically equivalent means. List of reference symbols 1 Gear Z Axis cross angle 2 W workpiece axis q inclination angle 3 first rolling peeling tool 3' second rolling peeling tool 4 tool axis 5 Tooth B Width 6 teeth 7 Tooth head 8 Tooth flank 9 Foot shape circle hi height 10 Tooth base 112 Height 11 Protuberance left sub-area length 12 Deposit h Sub-area Length 13 cutting edge tools 14 Tool axis 15 cutting 16 Cutting edge of the gear cutting tool 17 Cutting edge section 18 cutting edge section 19 Cutting edge of the prominence tool 20 cutting edge section 21 Cutting edge section 22 Control unit

Claims

Claims 1. A method for manufacturing a gear (1) comprising a first step in which a toothing (5) having teeth (6) with tooth flanks (8) is produced, a second step in which protuberances (11) are produced in the area between a tooth root (10) of the teeth (6) and a root form circle (9) by a machining process, and a third step in which backings (12) are produced in the tooth flanks (8) only in one or more first partial areas (h) of the width (B) of the toothing (5), characterized in that the protuberances (11) extend only over second partial areas (h) of the width (B) of the toothing (5), each of which has an overlap area with the first partial area (h).

2. Method according to claim 1, characterized in that the toothing is produced by a rolling process, skiving, gear hobbing or broaching and / or that the protuberances (11) are produced by skiving, broaching, gear hobbing or with an end mill.

3. Method according to claim 2, characterized in that the tooth flanks (8) are produced with a first tool, in particular a gear skiving tool (3), the cutting edges (16) of which run along a first contour and the backings are produced with a second tool, in particular a gear skiving tool, the cutting edges (19) of which run along a second contour different from the first contour.

4. Method according to claim 3, characterized in that the processing element adjacent to the tooth head (7) processes the area of ​​the tooth flank (8). Section (18) of the cutting edges (16) of the first tool (3) is thicker than the corresponding section (21) of the cutting edges (19) of the second tool (3'), and the section (20) of the cutting edges (19) of the second tool (3') that processes the protuberances (11) is thicker than the corresponding section (17) of the first tool (3). The method according to claim 4, characterized in that the height (hi) of the cutting teeth forming the cutting edges (16) of the first tool (3) is less than the height (112) of the cutting edges (19) of the second tool (3). Z) forming cutting teeth. Method according to one of claims 1 to 5, characterized in that the backings (12) are produced by using a cutting edge tool with a machining process.Device for manufacturing gears (1) comprising a rotary-driven first tool (3), which is a rolling tool for machining the workpiece, in particular a gear skiving tool, which is rotatably driven about a tool rotation axis and is designed such that a toothing (5) having teeth (6) with tooth flanks (8) can be produced with it by a rolling motion, in particular gear skiving, with a second tool (3') which is designed such that protuberances (11) can be produced with it in the area between a tooth root (10) of the teeth and a root forming circle (9) by chip removal, with a third tool (13) which is designed such that backings (12) in the tooth flanks (8) can be produced with it, and with a control device for controlling the tools (3, 3', 13), characterized in that the control device (22) is configured such that is that during the process of... The device is driven by a gear (1) manufactured according to the method of any one of claims 1 to 6. The device according to claim 7 is characterized in that the second tool (3') is a gear skiving tool, wherein the section (18) of the cutting edges (16) of the first tool (3) adjacent to the tooth head (7) and machining the area of ​​the tooth flank (8) is thicker than the corresponding section (21) of the cutting edges (19) of the second tool (3'), and that the section (20) of the cutting edges (19) of the second tool (3') machining the protuberances (11) is thicker than the corresponding section (17) of the first tool (3). The device according to claim 7 or 8 is characterized in that the third tool (13) is a cutting edge tool rotatable about a workpiece axis (2). Method or device characterized by one or more of the characterizing features of one of the preceding claims.

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