METHOD AND DEVICE FOR SMOOTHING THE FLAWS OF THE TEETH OF INTEGRED WORKPIECES, AND TOOL FOR CARRYING OUT THE METHOD

Description

field of technology

[0001] The invention relates to a method and a device for fine machining toothed workpieces with a tool designed in the manner of a skiving wheel, driven by a tool spindle for rotation about a tool axis, which has machining teeth that engage in a rolling motion in tooth gaps of the workpiece supported by a workpiece spindle arranged skew to the tool axis of rotation and driven synchronously for rotation about a workpiece axis of rotation. The invention also relates to a tool for carrying out the method. State of the art

[0002] Gear skiving tools are known in the prior art in a variety of forms. For example, from DE 2 43 514, EP 2 665 574 B1, US Pat. No. 3,264,940, or EP 2 520 390 B1, which implement a method according to the preamble of claim 1, represent a device according to the preamble of claim 7, and disclose a tool according to the preamble of claim 13. Summary of the invention

[0003] The invention is based on the object of reducing the surface roughness of the tooth flanks of the teeth of toothed workpieces.

[0004] The object is achieved by the processing method specified in claim 1, the device for carrying out the method characterized in claim 7 and the tool for carrying out the method specified in claim 13. The subclaims represent advantageous developments of the independent claims.

[0005] First and foremost, the invention proposes using a smoothing tool as the machining tool, which, except for the machining costs, otherwise has the shape of a skiving wheel. The machining teeth of the skiving wheel engage in the tooth gaps of the already toothed work gear. The penetration depth, i.e., the chip thickness or cutting depth, is set such that the machining edges of the tool's machining teeth, which in a known skiving wheel engage in a cutting action with the tooth flanks of the work gear teeth, only perform a smoothing function. To this end, it is proposed in particular that the rounding radius of the machining edges of the tool according to the invention be larger than that of a known skiving wheel. The rounding radius of the machining edges is, in particular, larger than the penetration depth of the machining edges into the surface of the tooth flank to be machined.The material of the workpiece wheel is of such quality that the machined edges have a material-forming effect. They push sections of the structures forming the roughness that protrude beyond a smoothing plane into neighboring areas that lie below the smoothing plane. The plane along which the machined edges move thus lies between a first plane defined by the peaks of the structures forming the roughness and a second plane defined by the valleys between the structures forming the roughness. The fillet radius is preferably larger than the distance between the smoothing plane and the first plane running through the peak contours. A center point of the fillet thus preferably lies outside the volume extending between the first plane and the second plane. The method according to the invention is particularly suitable for surface smoothing of workpieces made from heat-treatable steel or nitrided steel.The tensile strength of the workpiece material is preferably below 1350 N / mm². The process can be applied to internal or external gears. The teeth of the machining tool can be formed by internal or external gears. The rounding radius of the machined edges is at least 50 micrometers. However, the rounding radius can also be at least 100 micrometers or at least 150 micrometers. Short description of the drawings

[0006] The invention is explained in detail below with reference to the accompanying drawings. They show: Fig. 1 schematically shows the spatial arrangement of a tool 1, which is driven in rotation about a tool axis 3, to a workpiece 2, which is driven in rotation about a workpiece axis 4, Fig. 2 enlarges the illustration according to the section line II-II in Figure 1the engagement of the machining teeth 7 in tooth gaps 6 of the gearing of the work wheel 2, Fig. 3 the representation according to the section line III-III in Figure 1 the engagement of a machining tooth 7 in the surface of a tooth flank 9 of a tooth 5, Fig. 4 schematically shows the essential part of a device according to the invention with a workpiece spindle 17 carrying a tool 1 and a workpiece spindle 15 carrying a work wheel 2. Description of the embodiments

[0007] The Figure 4 shows schematically a device for fine machining of gears 2. In the embodiment according to Figure 4 The gear 2 has an internal toothing with teeth 5, each with tooth flanks 9. The toothing was created in a previous machining process, for example, by gear skiving. The tooth flanks 9 can be coarsely toothed. However, it is also possible that the surfaces of the tooth flanks 9 have already been finished.

[0008] At the Figure 4 The device according to the invention shown can be a special device which is exclusively intended for the fine machining of already pre-toothed gears 2. However, it is also intended that the device not only Figure 4illustrated tool spindle 18 with a smoothing tool 1. It is also provided that the device can have a second tool, which, for example, produces the gearing. With the gear cutting tool, not shown, the gearing of the work gear 2 can be carried out by gear skiving. In such gear skiving, the axes 3 of work gear 2 and 4 of tool 1 are skewed to one another, so that cutting edges of cutting teeth of the gear skiving wheel produce the tooth gaps between the teeth in a screw-rolling motion. This is done with a feed in the direction of tooth flank extension. The gearings of the work gear and skiving wheel mesh with each other in a screw-rolling motion.

[0009] While the previously described skiving tool for toothing the work gear has 2 cutting edges with a small rounding radius, the one in the Figure 4The tool 1 shown, which has the shape of a skiving wheel, has machining teeth 7 whose machining edges 8 have a rounding radius with a larger value.

[0010] The kinematics of the skiving movement, which is used for the gear cutting described above, but which is also used for the inventive fine machining of the tooth flanks 9, is described in the Figures 1 and 2 explained. The Figure 1 shows in perspective the relative spatial position of tool 1 and work wheel 2 to each other. Figure 2illustrates, in the form of a sectional view, the engagement of the cutting teeth or machining teeth 7 in the tooth gaps 6 between the teeth 5 of the gearing of the work wheel 2. The machining edges 8 machine the tooth flanks 9 of the teeth 5 by rolling along the tooth flanks 9 in the circumferential direction of the work wheel 2 or the tool 1. Due to the angle of inclination of the two axes of rotation 3, 4 to one another, the machining edges 8 also move in the feed direction designated in Figures 1 and 3 by the reference number 12, which extends in the direction of tooth extension.

[0011] The Figure 3 shows schematically the operation of the method according to the invention. The rough or already finely machined tooth flank 9 of the tooth 5 has a roughness with a roughness depth T. The roughness of the tooth flank 9 is Figure 3indicated by the structures 10. These structures may be traces of the previous machining. The machining tooth 7 of the tool 1 has a machining edge 8, which is Figure 3 shown cross-section runs on a circular arc line from a rake face 14 to a flank 13. The machining edge 8 thus has an edge rounding with a radius R around a center point.

[0012] The two rotational axes 3, 4 are spaced apart such that the machining edge 8 only comes into contact with the tooth flanks 9 during the screwing relative movement of tool 1 and work gear 2, but does not enter the tooth flanks 9 in a cutting manner. In particular, it is intended that the machining edges 8 do not reach into the deepest regions of the structures 10 of the tooth flanks 9, i.e., not into the deepest surface sections of the roughening.

[0013] However, the machining edges 8 engage more deeply into the parallel surface e1 to the tooth flank surface formed by the tips of the structures 10 in order to smooth the tips 10 of the rough tooth flanks 9 during machining, whereby their material is pressed into the adjacent valleys between the tips 10.

[0014] In the Figure 3is a plane that runs through the highest elevations 10 of the tooth flank 9, designated e1. E3 designates a plane that runs through the deepest regions of the tooth flanks 9, so that the roughness depth T is the distance between the two planes e1 and e3. For machining according to the invention, the device is adjusted such that the rounded machining edge 8 moves along a plane e2 that lies between the plane e1 and the plane e3, i.e., that passes through the region of the structures 10 that form the roughness. The distance E between the first plane e1 and the second plane e2 can be referred to as the cutting depth or engagement depth. According to the invention, this is smaller than the rounding radius R of the machining edge 8.As a result of this dimensioning, the machining edge 8 does not work in a cutting manner, but in a forming manner, by pushing the material of the sections of the tooth flank 9 projecting beyond the second plane e2 into the depression located between two tips 10.

[0015] While cutting edges on skiving tools have a rounding radius of less than 20 micrometers, the rounding radius of the machining edges 8 has values ​​greater than 50 micrometers. In preferred methods or devices, the rounding radius of the machining edges 8 is at least 100 micrometers or at least 150 micrometers.

[0016] In the method according to the invention, the machining edges 8 smooth the tooth flanks 9 without removing any chips.

[0017] The device according to the invention has a control device, wherein the control device 20 is programmed in such a way that the rotational axes 3, 4 are spaced from one another in such a way and the machining teeth 7 are designed in such a way that the machining teeth 7 act on the tooth flanks 9 in a smoothing manner without chip removal.

[0018] In the process and in the device, the rounding radius R of the machining edges 8 can be greater than the chip thickness or cutting depth.

[0019] In the process and the device, the workpiece 2 can be made of a tempering steel or nitriding steel.

[0020] In the process and the device, the tensile strength of the material of the workpiece 2 can be a maximum of 1350 N / mm 2<.

[0021] In the method and in the device, the workpiece 2 can have an internal toothing or an external toothing, the tooth flanks 9 of which are smoothed by the machining edges 8.

[0022] In the method and in the device, the processing teeth 7 can be formed by an internal toothing or an external toothing.

[0023] In the tool used to carry out the process, the rounding radius R of at least one machining edge 8 is greater than 50 micrometers. List of reference symbols

[0024] 1 Tool E Depth of cut 2 Work wheel G Smoothing depth 3 Tool axis R Surface roughness 4 Workpiece axis R Rounding radius 5 Tooth 6 Gap between teeth e1 level 7 machining tooth e2 level 8 machining edge e3 level 9 tooth flank 10 structure 11 smoothed tooth flank 12 axial feed component 13 open space 14 chip surface 15 Workpiece spindle 16 drive motor 17 tool spindle 18 drive motor 20 steering

Claims

1. A method for finishing toothed workpieces (2) with a tool (1) that is designed in the form of a circular skiving cutter and rotationally driven by a tool spindle (17), wherein said tool has machining teeth (7) that engage into tooth gaps (6) of the workpiece (2) in a rolling motion, and wherein said workpiece is carried by a workpiece spindle (15) that is arranged in a skewed manner relative to the tool rotational axis (4) and driven synchronous thereto such that machining edges (8) of the machining teeth (7) machine the tooth flanks (9) of the teeth (5) of the workpiece (2) in the direction in which the tooth flanks extend, characterized in that the machining edges (8) act upon the tooth flanks (9) in a smoothing manner without metal removal.

2. The method according to claim 1, characterized in that the rounding radius (R) of the machining edges (8) is greater than the machining thickness or cutting depth (E).

3. The method according to one of the preceding claims, characterized in that the workpiece (2) consists of a tempering steel or nitriding steel.

4. The method according to claim 3, characterized in that the tensile strength of the material of the workpiece (2) amounts to no more than 1350 N / mm2.

5. The method according to one of the preceding claims, characterized in that the workpiece (2) has an internal toothing or an external toothing, the tooth flanks (9) of which are smoothed by the machining edges (8).

6. The method according to one of the preceding claims, characterized in that the machining teeth (7) are formed by an internal toothing or an external toothing.

7. A device for finishing toothed workpieces (2) with a tool (1) that is designed in the form of a circular skiving cutter and rotationally driven about a tool rotational axis (4) by a tool spindle (17), wherein said tool has machining teeth (7) that engage into tooth gaps (6) of the workpiece (2) in a rolling motion, wherein said workpiece is carried by a workpiece spindle (15) that is arranged in a skewed manner relative to the tool rotational axis (4) and rotationally driven synchronous thereto about a workpiece rotational axis (3), and wherein said device comprises a control (20), which is programmed in such a way that machining edges (8) of the machining teeth (7) machine the tooth flanks (9) of the teeth (5) of the workpiece (2) in the direction in which the tooth flanks extend, characterized in that the control unit (20) is programmed in such a way, the rotational axes (3, 4) are spaced apart from one another in such a way and the machining teeth (7) are designed in such a way that the machining teeth (7) act upon the tooth flanks (9) in a smoothing manner without metal removal.

8. The device according to claim 7, characterized in that the rounding radius (R) of the machining edges (8) is greater than the machining thickness or cutting depth (E).

9. The device according to claim 7 or 8, characterized in that the workpiece (2) consists of a tempering steel or nitriding steel.

10. The device according to claim 9, characterized in that the tensile strength of the material of the workpiece (2) amounts to no more than 1350 N / mm2.

11. The device according to one of the claims 7 to 10, characterized in that the workpiece (2) has an internal toothing or an external toothing, the tooth flanks (9) of which are smoothed by the machining edges (8).

12. The device according to one of the claims 7 to 11, characterized in that the machining teeth (7) are formed by an internal toothing or an external toothing.

13. A tool for carrying out the method according to one of the claims 1 to 6, wherein said tool is rotationally driven about a tool rotational axis (4), comprises machining teeth (7) with a machining edge (8) having an edge rounding (R) and is designed in the form of a circular skiving cutter, characterized in that the rounding radius (R) of the machining edge (8) is greater than 50 micrometer.