Dressing tool for dressing grinding worms for generating pre-toothed workpieces

Abstract

A dressing tool for dressing a grinding worm for generating a pre-toothed workpiece is configured to rotate about a dressing rotation axis A and has a dressing flank surface that forms an annulus in a projection plane perpendicular to the dressing rotation axis of the dressing tool, the annulus defining a radial direction by a radial coordinate r and a circumferential direction by an angular coordinate φ. The dressing flank surface is provided with an intentionally generated dress flank modification, and the dress flank modification projected onto the annulus can be described as a two-dimensional Fourier series depending on the radial coordinate r and the angular coordinate φ, the Fourier series having at least one non-zero Fourier coefficient for a circumferential frequency component that is non-zero with respect to the angular coordinate.

Description

[Technical Field]

[0001] The present invention relates to a dressing tool for dressing a grinding worm for generating pre-toothed workpieces, a method for manufacturing such a dressing tool, and a conditioning device configured to carry out such a manufacturing method.The present invention further relates to a method for dressing a grinding worm for generating pre-toothed workpieces using such a dressing tool, and a method for producing a modified surface structure on the tooth flank of a pre-toothed workpiece using a grinding worm dressed with such a dressing tool. [Background technology]

[0002] Particularly in the field of electric vehicles, the topic of NVH (noise-vibration-harshness), especially in the gear transmission section of a vehicle, is becoming increasingly important due to the absence of the dominant background noise of a combustion engine. Requirements regarding noise excitation behavior are often specified in the form of predefined limit values ​​in the noise frequency spectrum. Whether a workpiece fulfills these requirements is usually checked randomly on an end-of-line (EOL) test bench. If the measured amplitude of individual noise frequencies exceeds the predefined limit values, the corresponding workpiece is rejected.

[0003] A typical noise frequency spectrum for rotating gears consists of the gear meshing frequency (f ZE The dominant amplitudes at noise frequencies correspond to the associated harmonics at the gear meshing order (ZEO) and the corresponding gear meshing order (ZEO). These dominant noise frequencies are generally caused by transmission errors resulting from mesh stiffness varying along the length of the contact path. The progression of mesh stiffness as a function of position along the length of the contact path repeats periodically with mesh pitch, resulting in the dominant noise frequencies mentioned above. Another cause can be "generating holes" created during manufacturing, i.e., recessions in the material relative to the desired profile line.

[0004] Overall, any transmission error in the gear mechanism under load can lead to noise excitation that can be perceived as an unpleasant noise. For example, if the dressing tool exhibits a certain waviness that exceeds the profile height, the waviness will be transferred to the worm flank and subsequently lead to profile shape deviations in the workpiece.

[0005] Constant vibrations around the machine tools used to machine the pre-toothed workpieces can also lead to measurable tooth flank ripples in the tooth flanks, which can result in objectionable noise characteristics of the gear train.

[0006] Grooves extending across the face width of the gear train can also lead to noise excitation. In general, periodic surface structures, especially in the direction perpendicular to the contact line of mating spur gears, can lead to the excitation of noise frequencies that dominate the noise frequency spectrum of the gear train.

[0007] There are several approaches to improving the noise excitation behavior of gear trains. Transmission errors caused by deformation of the gear train under load can be effectively reduced by targeted (intentional) modifications to the tooth flanks. Pitch holes can be almost completely eliminated through optimized process control.

[0008] US Patent No. 5,649,999 discloses a generating grinding process in which a workpiece is machined with a grinding worm, whereby, in order to correct or prevent undesired flank waviness, corrections, in particular profile corrections, or profile waviness and / or defined periodic flank waviness are generated on the effective surface of the workpiece being machined by intentionally generating an oscillating movement caused by imbalance of the grinding worm and / or by eccentricity of the grinding worm.

[0009] The flank waviness on the workpiece caused by imbalance or eccentricity of the grinding worm is always of first order with respect to the worm rotation frequency, i.e., this method cannot generate flank waviness of higher orders with respect to the worm rotation frequency.

[0010] Patent Document 2 discloses a method for hardening tooth flanks by correction and / or modification in a gear cutting machine. In this method, gear pairs that are to be mated with each other are machined in a gearbox or test device, taking into account their respective mating flanks, and the tooth flanks of the workpieces are provided with periodic waviness correction or modification. According to this invention, a transmission error curve is determined by measuring the transmission error of the gear pair in a gear measuring device and / or a gearbox. The measurement results serve as input variables that define the amplitude, frequency, and phase position for the periodic flank waviness correction on the tooth flanks of the gear pair, which is generated in the gear cutting machine.

[0011] Periodically repeating surface structures tend to lead to excitation in a relatively narrow noise frequency band. Furthermore, as irregular a surface structure as possible leads to a very broad noise frequency spectrum that approximates "white" noise, i.e., a noise frequency spectrum with the same amplitude at all noise frequencies. This noise frequency spectrum, which tends to reduce the dominance of individual noise frequencies, is advantageous because it is perceived as less psychoacoustically unpleasant. Additionally, in the case of excitation with a broad noise frequency spectrum, the entire excitation energy is distributed over a wide frequency range, and therefore the noise amplitude of each individual frequency component tends to be smaller than in the case of excitation in a narrow frequency band.

[0012] When a workpiece is machined using a generating grinding process with a grinding worm, for example, a periodically repeating surface structure may occur on the tooth flank due to the dressing of the grinding worm used to machine the tooth flank. The dressing wheel used for dressing may have different abrasive grain sizes and shapes, as well as different distributions of abrasive grains around the circumference, due to the technique used, resulting in a dressing pattern on the surface of the dressing wheel. Because the dressing wheel typically rotates multiple times during one rotation of the grinding worm, this dressing pattern is periodically transferred onto the grinding worm during dressing in the direction of the worm thread. During subsequent grinding of the workpiece, periodic variations in the tooth flank surface may occur on the tooth flank of the workpiece in the form of grooves extending across the face width.

[0013] Patent document 3 discloses a method in which the rotation angle of the dressing wheel is coupled to the rotation angle of the grinding worm with an adjustable fixed ratio, a programmable variable ratio, or a stored stochastically varying ratio. The grinding worm moves along its axis relative to the workpiece during grinding (shift feed) so that each point on the tooth flank of the workpiece's teeth corresponds exactly to one point on the flank of the grinding worm thread.

[0014] The grooves mentioned above can be destroyed by deliberately selecting the shift feed, which destroys the periodicity of the surface structure of the tooth flank and thus in principle achieves a more pleasant noise behavior, but the structure transferred to the tooth flank is highly dependent on the manufacturing-related stochastic dressing pattern on the surface of the dressing wheel and can therefore only be influenced by the shift feed during grinding of the workpiece. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] German Patent Application Publication No. 102012015846 [Patent Document 2] German Patent Application Publication No. 102013003795 [Patent Document 3] German Patent Application Publication No. 19905136 Summary of the Invention

[0016] In a first aspect, the object of the present invention is to provide a dressing tool with which a grinding worm for generating machining of pre-toothed workpieces can be dressed so that the grinding worm intentionally generates a modified surface structure on the tooth flank of the pre-toothed workpiece, and this modified surface structure is suitable for influencing the noise behavior of the workpiece.

[0017] This object is achieved by the method of claim 1. Further embodiments are defined in the dependent claims.

[0018] Therefore, a dressing tool is proposed to dress the grinding worm for generating the pre-toothed workpiece. the dressing tool is configured to rotate about a dressing rotation axis and has dressing flank surfaces that form an annulus in a projection plane perpendicular to the dressing rotation axis, the annulus defining a radial direction in radial coordinates and a circumferential direction in angular coordinates; The dress flank surface is provided with an intentionally generated dress flank modification, and the dress flank modification projected onto the ring can be expressed as a two-dimensional Fourier series depending on the radial and angular coordinates.

[0019] The Fourier series has at least one non-zero Fourier coefficient for a non-zero circumferential frequency component with respect to the angular coordinate. Figuratively speaking, this means that the dress flank modification exhibits waviness in the circumferential direction.

[0020] The waviness of the dressing tool in the circumferential direction can be transferred to the grinding worm flank of the worm thread during dressing by appropriately specifying the rotational frequency ratio or rotational angle coupling between the dressing tool and the grinding worm to be dressed, thereby forming a worm modification with a thread waviness on the grinding worm flank. Furthermore, this thread waviness can be used to generate special tooth flank ripples on the tooth flank of a pre-toothed workpiece machined with the grinding worm. Therefore, the dressing tool proposed here represents a particularly simple and elegant method of dressing the grinding worm using the grinding worm so that intentional tooth flank ripples can be generated on the workpiece with high flexibility in terms of the wavelength and phase position of the tooth flank ripples.

[0021] In contrast to the purely radial waviness of the dressing tool, which is transferred independently of the speed ratio between the dressing tool and the dressed grinding worm, the circumferential waviness can be transferred in a desired manner to the dressed grinding worm by specifically specifying the speed ratio or rotation angle coupling between the dressing tool and the dressed grinding worm. Thus, the circumferential waviness on the dressing tool surface provides an additional degree of freedom for the targeted transfer of the dress flank modifications.

[0022] In particular when dressing a grinding worm, in order to obtain a continuous transition after one revolution of the dressing tool, the dressing flank correction preferably has a 2π periodicity with respect to the angular coordinate, i.e. the dressing flank correction has an integer number of wave periods with respect to the angular coordinate.

[0023] Hereinafter, the term "wavefront" refers to a line of constant phase, in other words a line that does not undergo amplitude modulation.

[0024] In one embodiment, the Fourier series has no non-zero Fourier coefficients for non-zero radial frequency components in the radial direction, such that the intentionally generated dress flank modification is circumferentially undulating and has a wavefront in the form of radially oriented lines of constant phase when projected onto the annulus. In other words, in this embodiment, the dress flank modification has undulations that occur exclusively in the circumferential direction.

[0025] In another embodiment, the two-dimensional Fourier series has at least one non-zero Fourier coefficient for non-zero radial and circumferential frequency components, such that the dress flank modification projected onto the annulus forms a checkerboard-like structure with wave crests and wave troughs offset from one another in a checkerboard-like manner. Adjacent wave troughs and wave crests can be offset to form radial undulations along radial paths extending parallel to the radial direction. If the radial undulations of adjacent radial paths are offset by exactly 180°, the circumferential undulations will be formed along circumferential paths extending parallel to the circumferential direction, and the circumferential paths will be separated in the radial direction by half the radial wavelength of the radial undulations. Such a chessboard-like structure can be mathematically described as an additive superposition of two partial waves, the partial waves projected onto the unfolded ring having inclined wavefronts, i.e., wavefronts inclined by an inclination angle α other than 0°, ±90°, or ±180° with respect to the unfolded circumferential direction, the inclined wavefront of the first partial wave having a positive slope (α>0°) and the inclined wavefront of the second partial wave having a negative slope (α<0°), the first partial wave having the same order in the circumferential direction (i.e., the same number of wave periods) and the same order in the radial direction as the second partial wave.

[0026] In a preferred embodiment, the chessboard-like structure is oriented on the ring so that adjacent wave troughs and wave crests are arranged circumferentially along a spiral branch that extends spirally on the ring. Here, the number of wave periods along the spiral branch in the angular coordinate range 2π (i.e., corresponding to one rotation of the dressing tool) is referred to in this context as the order of the spiral branch direction. The chessboard-like structure can also be oriented and / or distorted so that two or more spiral branches result. Preferably, after one rotation of the dressing tool, the transition of the spiral branch or branches is continuous. Such a structure with spiral branches can also be mathematically described as an additive superposition of two partial waves, which, when projected onto the ring, have an inclined wavefront. When the number of spiral branches is less than twice the spiral branch directional order, the structure can be described by an additive superposition in which the inclined wavefront of the first partial wave has a positive slope and the inclined wavefront of the second partial wave has a negative slope, and the first partial wave has a circumferential order that is greater than the number of spiral branches than the circumferential order of the second partial wave.When the number of spiral branches is greater than or equal to twice the spiral branch directional order, the structure can be described using an additive superposition in which the inclined wavefronts of the first and second partial waves both have a positive slope or both have a negative slope, and the circumferential order of the first partial wave is greater than the circumferential order of the second partial wave by twice the spiral branch directional order.

[0027] In a further aspect, the present invention provides a method of manufacturing a dressing tool as set out above, the method comprising the steps of: Producing a coated substrate of a dressing tool in a positive process; Intentionally creating dress flank modifications using a conditioning tool, in particular a rotating conditioning disk perpendicular to the dress flank surface; Includes:

[0028] Preferably, a narrow rotating conditioning disc is used, for example a conditioning disc having a rounded head on its outer periphery (i.e. a crowning of the side of the conditioning disc in the axial direction), where the radius of the rounding corresponds to a maximum of one-quarter of the radial wavelength in the radial direction, which corresponds to the wave period of the undulation in the radial direction.

[0029] Intentionally generating dress flank modifications is Driving the dressing tool to rotate around a dressing rotation axis; Driving the conditioning tool to rotate about a conditioning axis of rotation of the conditioning tool; moving the conditioning tool relative to the dressing tool in a direction having a component normal to the dressing flank surface to remove material from the dressing flank surface thereby generating a dressing flank modification; may include:

[0030] By removing material, conditioning tracks can be created on the dress flank surface that correspond to the wave troughs and have a width corresponding to half a radial wavelength in the radial direction. However, the width of the conditioning track can also be less than half a radial wavelength of the desired dress flank modification in the radial direction. In such cases, it may be necessary to create multiple adjacent conditioning tracks to create a complete wave trough.

[0031] Instead of a narrow conditioning disk, the conditioning tool can also have a ribbed periphery with at least two conditioning ribs. Each conditioning rib has a rounded head with a radius corresponding to up to one-quarter of the radial wavelength in the radial direction, and each conditioning rib can generate a conditioning track on the dressing flank surface. In such a case, the conditioning tool generates multiple conditioning tracks simultaneously, and therefore, depending on the number of conditioning ribs, the entire pattern of dressing flank modifications can be generated in a single pass. As with the conditioning disk (corresponding to a conditioning tool with a single conditioning rib), the orientation of the wave front can be adjusted by kinematic movement of the conditioning tool relative to the dressing tool.

[0032] The infeed movement of the conditioning tool relative to the dressing tool can be achieved by spatially moving the conditioning tool and / or by spatially moving the dressing tool. The infeed movement or resulting infeed position of the conditioning tool in a direction perpendicular to the dressing flank surface can be oscillated at an infeed frequency that is a predetermined fixed ratio to the rotation frequency of the dressing tool. This allows for variations in material removal along the conditioning trajectory, resulting in a corresponding waviness along the conditioning trajectory.

[0033] Depending on the dressing flank modification, the intentional generation of said dressing flank modification may be performed instead of or in addition to the oscillation of the infeed movement. generating a discrete or continuous axial conditioning movement along the conditioning axis of rotation; may include:

[0034] "Continuously" in this context means that the conditioning tool is in contact with the dressing tool while the axial conditioning movement is being performed, and therefore material removal occurs during the axial conditioning movement.

[0035] In this context, "discontinuous" means that the conditioning tool does not come into contact with the dressing tool while the axial conditioning movement is being performed, and therefore no material removal occurs during the axial conditioning movement.

[0036] An axial conditioning movement is understood as a relative movement between the dressing tool and the conditioning tool along the conditioning rotation axis. The conditioning tool and / or the dressing tool can be driven to perform the axial conditioning movement.

[0037] In response to the dress flank modification, the intentional generation of the above dress flank modification is generating, using a conditioning tool, a plurality of intersecting conditioning trajectories on the dressing flank surface at a predetermined angle by discontinuous and / or continuous axial conditioning movements along the conditioning rotation axis; and The infeed position of the conditioning tool relative to the dressing flank surface may have a constant value in a direction perpendicular to the dressing flank surface, or the infeed movement or infeed position of the conditioning tool may oscillate at an infeed frequency.

[0038] For example, a structure can be created in which wave troughs intersect and the material areas of the dress flank surface between them form ridges. Depending on the orientation of the intersecting wave troughs on the dress flank surface, these ridges can be arranged along helical branches that extend helically on the annulus.

[0039] Alternatively, the process for manufacturing the dressing tool may comprise: Manufacturing dressing tools in a negative process The negative process includes producing a negative mold by boring a negative substrate; Boring an intentional negative correction into a negative shape, so that the negative correction results in a dress flank correction; and / or generating mechanical and / or hydraulic tension in the negative substrate during the boring process, so that after the mechanical tension is released the boring negative has a negative modification resulting in a dress flank modification; may include:

[0040] The targeted negative modification can be bored into the boring negative using a suitable machining tool, in particular a lathe cutting tool, which is preferably movable relative to the negative along the negative rotation axis of the negative.

[0041] In particular, the intentional generation of negative corrections Driving the negative mold to rotate around the negative mold rotation axis at a rotation frequency; positioning a lathe cutting tool to generate a negative trajectory on at least one inside flank of the negative die; It may further include:

[0042] In a further aspect, the present invention provides a method for dressing a grinding worm for generating a pre-toothed workpiece, the method comprising the steps of: dressing the grinding worm using the dressing tool described above, so that the dressing flank modification results in a worm modification on the grinding worm flank of the worm thread of the grinding worm; Includes:

[0043] In order to intentionally generate periodic worm modifications on the grinding worm flank along the worm thread, there can be a predetermined fixed rotation angle coupling between the dressing tool and the grinding worm, in which case the worm modification represents a compressed image of the dressing flank modification with a constant compression rate, which depends on the speed ratio between the rotation of the dressing tool and the rotation of the grinding worm.

[0044] Alternatively, there can be a predetermined time-variable rotation angle coupling between the dressing tool and the grinding worm in order to specifically generate a non-periodic worm modification on the grinding worm flank along the worm thread, in which case the dressing flank modification is transferred as a worm modification with a non-constant compression ratio.

[0045] In a further aspect, the present invention relates to a method for dressing a grinding worm for generating pre-toothed workpieces, comprising in particular the method described above, defining a desired worm modification on a grinding worm flank of a worm thread of the grinding worm; - calculating back from the desired worm correction to obtain the corresponding dressing flank correction of the dressing tool for a selected fixed or variable rotation angle coupling between the dressing tool and the grinding worm; manufacturing a dressing tool with a corresponding dressing flank modification, in particular using the method described above; Dressing the grinding worm with a dressing tool by a selected fixed or variable rotation angle coupling, the dressing flank modification producing a desired worm modification along the worm thread; The present invention provides a method comprising:

[0046] In a further aspect, the present invention provides a method for generating a modified surface structure on a tooth flank of a pre-toothed workpiece, the method comprising the steps of: dressing a grinding worm suitable for generating pre-toothed workpieces by the method described above; Driving the grinding worm to rotate about a worm axis; Driving the pre-toothed workpiece to rotate about a workpiece axis; generating a relative movement between the grinding worm and the pre-toothed workpiece at a shift feed rate in a shift direction ("shift movement") parallel to the worm axis; generating a relative movement between the grinding worm and the pre-toothed workpiece in an axial direction parallel to the workpiece axis ("axial feed movement") at an axial feed rate; Including, The grinding worm and the pre-toothed workpiece are in rolling engagement, and the shift feed rate and the axial feed rate have a predetermined diagonal ratio such that the worm modification is transferred onto the tooth flank of the pre-toothed workpiece, thereby intentionally modifying the surface structure of the tooth flank.

[0047] The diagonal ratio is the ratio between the shift feed rate of the grinding worm in the shift direction and the axial feed rate of the grinding worm in the axial direction parallel to the workpiece axis. This diagonal ratio can be zero or non-zero. A zero diagonal ratio results in a profile modification on the tooth flank along the tooth flank depth direction. A non-zero diagonal ratio can result in a topological modification of the resulting tooth flank surface structure, i.e., a modification with components in both the tooth flank depth direction and the face width direction.

[0048] In addition, this process can also involve the generation of a relative movement between the grinding worm and the pre-toothed workpiece in a radial direction perpendicular to the workpiece axis ("radial infeed movement"). As a result, further modifications can be superimposed on the above-mentioned modifications of the surface structure of the tooth flank. In the case of conical workpieces, the radial infeed movement can be combined with the axial feed movement depending on the cone angle of the conical gear mechanism.

[0049] During generating, the worm correction causes variations in the penetration depth between the grinding worm and the pre-toothed workpiece, thus generating tooth flank waviness along the contact trajectory on the tooth flank, which corresponds to the line along which the contact point between the grinding worm and the pre-toothed workpiece in rolling engagement moves on the tooth flank during generating.

[0050] If the dressing tool has a chessboard-like structure in which adjacent wave troughs and wave crests are circumferentially arranged along spiral branches that extend spirally on the ring and are thus oriented to form a spiral undulation, the fixed rotation angle coupling between the dressing tool and the grinding worm during dressing can be selected so that the spiral branches are imprinted on the worm contact path on the grinding worm flank. The worm contact path corresponds to the line along which the contact point between the grinding worm and the pre-toothed workpiece in rolling engagement moves on the grinding worm flank during generating.

[0051] That is, the spiral waviness that occurs along the spiral branch on the dressing flank surface can be intentionally transferred from the dressing tool to the tooth flank along the contact trajectory by the grinding worm.

[0052] In some embodiments, the intentional movement of the grinding worm relative to the pre-toothed workpiece in the shift direction and in the axial direction is superimposed with uncontrolled, in particular stochastic, additional movements, resulting in uncontrolled variations in the penetration depth. Such uncontrolled additional movements can be caused, for example, by unavoidable vibrations of the generating grinding machine that performs the generating process.

[0053] By intentionally varying the penetration depth using worm modifications of the dressed grinding worm as described above, a suitable basic pattern can be generated on the tooth flank, which can be made more diffuse by superimposing uncontrolled variations in the penetration depth, which can lead to an optimization of the noise behavior. In this way, for example, unavoidable vibrations can be intentionally used to improve the noise behavior.

[0054] Preferably, the intentional variation of the penetration depth caused by the dressed grinding worm as described above has a modulation amplitude in the range of 0.2 to 5 times the variation scale of the uncontrolled deviation of the penetration depth, The variability measure corresponds in particular to the standard deviation or interquartile range of the uncontrolled deviation of the indentation depth, In particular, a variation scale of the uncontrolled variation of the indentation depth is determined, and depending on the determined variation scale, the modulation amplitude, and thus in particular the amplitude of the worm correction and therefore in particular the amplitude of the dress flank correction, is specially selected.

[0055] In a further aspect, the present invention provides a method for producing a composition comprising: a conditioning tool, in particular a narrow conditioning disc, which is mounted on the conditioning spindle, i.e. a conditioning disc having a rounded head on its outer periphery, the radius of the rounding corresponding to a maximum of one-quarter of a radial wavelength in the radial direction, the radial wavelength corresponding to the wave period of the undulation in the radial direction; a dressing spindle configured to receive a dressing tool that rotates about a dressing axis of rotation; a conditioning control configured to move the conditioning tool relative to the dressing tool such that the dressing tool is provided with the dress flank modification described above; A conditioning device is provided, comprising:

[0056] Preferred embodiments of the present invention are described below with reference to the drawings, which are for illustrative purposes only and are not to be construed as limiting. [Brief explanation of the drawings]

[0057] [Figure 1A] FIG. 1A is a schematic front view of a dressing tool in a projection plane perpendicular to the dressing rotation axis of the dressing tool. [Figure 1B] FIG. 1B is a projection of the dress flank surface in the unfolded configuration. [Figure 2] FIG. 2 is a diagram of a first exemplary pattern of dress flank modifications. [Figure 3] FIG. 3 is a diagram of a second exemplary pattern of dress flank modification. [Figure 4] FIG. 4 is a diagram of a third exemplary pattern of dress flank modification. [Figure 5]FIG. 5 is a diagram of a fourth exemplary pattern of dress flank modification. [Figure 6A] FIG. 6A is a diagram of a fifth exemplary pattern of dress flank modification. [Figure 6B] FIG. 6B is a diagram of a first partial wave pattern for an additive mathematical description of the fifth example pattern of FIG. 6A. [Figure 6C] FIG. 6C is a diagram of a second partial wave pattern for the additive mathematical description of the fifth example pattern of FIG. 6A. [Figure 7A] FIG. 7A is a diagram of a first exemplary arrangement of spiral branches on a dress flank surface. [Figure 7B] FIG. 7B is a diagram of a second exemplary arrangement of two spiral branches on the dress flank surface. [Figure 7C] FIG. 7C is a diagram of a third exemplary arrangement of three spiral branches on the dress flank surface. [Figure 7D] FIG. 7D is a diagram of a sixth exemplary pattern of a dress flank modification having two spiral branches. [Figure 7E] FIG. 7E is a diagram of a sixth exemplary pattern transferred to the projection surface of the dress flank surface. [Figure 8A] FIG. 8A is a diagram of a conditioning device according to one embodiment of the present invention. [Figure 8B] FIG. 8B is an enlarged cross-sectional view of a portion of a conditioning tool having a plurality of conditioning ribs. [Figure 9] FIG. 9 is a diagram of a negative boring die for producing a dressing tool according to the invention. [Figure 10A] FIG. 10A is a diagram of the negative mold tensioned using the deformation device. [Figure 10B] FIG. 10B is a view of an open boring negative mold for producing a dressing tool according to the present invention. [Figure 11] FIG. 11 is a projection of the grinding worm flank of the worm thread of the grinding worm in developed form. [Figure 12] FIG. 12 is a schematic diagram of a generating grinding machine. [Figure 13] FIG. 13 is a partially enlarged view of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0058] [Dressing tools] FIG. 1A shows a schematic front view of a dressing tool 33, in which the dressing tool 33 has a dressing flank surface 331 that forms a ring in a projection plane perpendicular to the dressing rotation axis A of the dressing tool 33, the ring defining a radial direction by a radial coordinate r and a circumferential direction by an angular coordinate φ, the ring having an inner radius r A It has.

[0059] In FIG. 1B, the ring is shown schematically in unfolded form, with a profile height d in the radial direction and a length of 2π in the circumferential direction.

[0060] 2-6A show schematic examples of various wave-shaped patterns that intentionally generated dress flank modifications can exhibit on the dress flank surface shown in FIG. 1B, where wave crests are shown schematically as light shading and wave troughs as dark shading.

[0061] In the following sections, we explain how these two-dimensional corrugated patterns can be mathematically described. To this end, we use a pattern rectangle with a pattern height Δr′ in the vertical direction (hereafter referred to as the radial direction) and a pattern length 2π in the longitudinal direction (hereafter referred to as the circumferential direction). The pattern can be described as a two-dimensional real-valued Fourier series f(φ,r′) (i.e., a real-valued Fourier series in two real-valued variables φ and r′) depending on the angular coordinate φ∈[0,2π] and the radial coordinate r′∈[0,Δr′] of the pattern rectangle, respectively.

number

[0062] Index

number

number

[0063] The Fourier coefficients that indicate the amplitude and phase position of the corresponding frequency component are c n,m The Fourier coefficients are generally expressed in complex form as

number

number

[0064] Due to the definition of the radial fundamental frequency chosen above, the pattern repeats periodically in the radial direction with a pattern period Δr′.

[0065] The radial phase position f(φ,r) of the dress flank modification on the dress flank surface 331 can be chosen arbitrarily and expressed as a corresponding linear coordinate transformation f(φ,r′)→f(φ,r) from the radial coordinate r′ of the pattern rectangle to the radial coordinate r of the dress flank surface. Here, the profile height d over which the dress flank modification extends can correspond to the pattern period Δr′ or may be chosen to be smaller or larger (because the pattern is periodically continuous with the pattern period Δr′). In other words, this means that any radial section of the periodic exemplary pattern mathematically described below can be applied to the dressing tool as a dress flank modification.

[0066] Therefore, the phase position of the pattern on the pattern rectangle is not important, and the Fourier coefficient c n,m and c -n,-m can be chosen to be the complex conjugate, i.e.

number

[0067] Figuratively speaking, a dress flank modification can be described as a portion of a wave-shaped pattern on a pattern rectangle, or as the superposition of two or more wave-shaped sub-patterns on a pattern rectangle, each of which can have a periodic undulation in the radial and / or circumferential directions. It should be noted that only the absolute phase position of the resulting pattern is not important. On the other hand, when describing the resulting pattern by superposing several wave-shaped sub-patterns, the relative phase positions of the sub-patterns with respect to each other are important.

[0068] Hereinafter, for each of these wave-shaped patterns / partial patterns, the number of wave periods on the pattern rectangle in the radial direction will be referred to as the radial order N, and the number of wave periods in the circumferential direction will be referred to as the circumferential order M. The wave period in the radial direction is the radial wavelength λr’ and the wave period in the circumferential direction is given by the offset angle Δφ in the following context. U ("circumferential wavelength"). The circumferential order M corresponds to the subscript value |m|, since the circumferential fundamental frequency is chosen so that k1 = 1, and the radial order N corresponds to the subscript value |n|, since the radial fundamental frequency is chosen so that R1 = 1 / Δr'.

[0069] In the embodiment shown in Figure 2, the pattern has wavefronts in the form of lines of constant phase, which form continuous straight lines that are projected onto the unfolded annulus. As shown in Figure 2, these lines are inclined by an inclination angle α with respect to the unfolded circumferential direction, and are offset in the circumferential direction by an offset angle Δφ. U To ensure that the pattern of dress flank modifications can be periodically continuous after one revolution, only discrete values ​​of the tilt angle α are possible, i.e.

number

number

number

number

[0070] On the other hand, if the line of constant phase has a positive slope, then the following pair of frequency components have non-zero Fourier coefficients:

number

number

[0071] Since the waveform does not necessarily have to be a pure sinusoid, other Fourier coefficients may be non-zero. In particular, harmonics of the above-mentioned Fourier coefficients may be non-zero, i.e., the Fourier coefficients where n is an integer multiple of N and m is an integer multiple of M. In this case, the relative phase angle of the harmonics with respect to the lowest frequency has a crucial effect on the resulting pattern and must be taken into account.

[0072] The table below summarizes the dress flank correction parameters for Figure 2.

[0073] [Table 1]

[0074] Specifically, the following applies to the patterns in Figure 2:

number

[0075] In Figure 3, the tilt angle α is exactly 90°, i.e. the wavefront of the dress flank modification is radially aligned when projected onto the annulus. This case is due to the non-zero radial frequency component R n corresponds to a complex Fourier series with no non-zero coefficients for . The dress flank correction shown here is circumferentially continuous, i.e., the wave-shaped dress flank correction has an integer number of wave periods per revolution of the dressing tool (2π periodicity). The table below summarizes the parameters of the dress flank correction in Figure 3.

[0076] [Table 2]

[0077] Specifically, the following applies to the patterns in Figure 3:

number

[0078] In FIG. 4, the tilt angle α is exactly 0°, i.e. the wavefront extends in a straight line parallel to the circumferential direction and has a radial wavelength λ r In this case, the non-zero circumferential frequency component k m corresponds to a complex Fourier series with no non-zero coefficients for . The table below summarizes the parameters for the dress flank correction in Figure 4.

[0079] [Table 3]

[0080] Specifically, the following applies to the patterns in Figure 4:

number

[0081] In the embodiment shown in FIG. 5, the two-dimensional complex Fourier series has non-zero radial frequency components R n and non-zero circumferential frequency component k m , and the corrugated dress flank modifications are such that when projected onto the unfolded ring, they form a checkerboard-like structure with offset wave crests and troughs. Mathematically, the pattern in Figure 5 is W1 (φ, r') and the second partial wave f W2 It can be written as an additive superposition of (φ,r').

number

[0082] 5, adjacent wave troughs and wave crests are offset from one another, thus forming radial undulations along radial paths R1, R2, respectively, extending parallel to the radial direction. In the example shown in FIG. 5, the radial undulations of adjacent radial paths are offset by exactly 180°, thereby forming circumferential undulations along circumferential paths U1, U2, extending parallel to the circumferential direction, where the circumferential paths U1, U2 are spaced apart in the radial direction by half the radial wavelength λ. r’ The following table summarizes the dress flank correction parameters for Figure 5.

[0083] [Table 4]

[0084] Specifically, the following applies to the patterns in Figure 5:

number

number

[0085] FIG. 6A illustrates the first partial wave f shown in FIG. 6B. W1 (φ,r') and the second partial wave f shown in Figure 6C W2 shows a spiral pattern that can be mathematically described as an additive superposition with (φ,r').

number

[0086] 5, the radial undulations of adjacent radial paths R1, R2 in FIG. 6A are offset from each other by a value different from 180°, so that adjacent wave troughs and wave crests are arranged circumferentially along a spiral branch S1 that extends spirally on the ring, thus forming a spiral undulation. The number of wave periods along the spiral branch S1 is hereinafter referred to as the order L in the spiral branch direction.

[0087] The height of the spiral branch over one rotation of the dressing tool is half the radial wavelength, λ r’ / 2 and the number of spiral branches

number

number

[0088] To ensure a continuous transition of the spiral branches after one revolution of the dressing tool, two cases must be distinguished: 1. The degree L of the freely selected spiral branch direction is an integer. In this case, the rising height of the spiral branch is half the radial wavelength λ. r’ / 2, i.e., the number of spiral branches i s is an even number. 2. The degree L of the freely selected spiral branch direction is a half integer. In this case, the rising height of the spiral branch is half the radial wavelength λ. r’ / 2, i.e., the number of spiral branches i sis an odd number.

[0089] In FIG. 6A, the order of the spiral branch direction is L=5.5, and the rising height is just λ r’ / 2, which means that there is exactly one spiral branch, i.e., i s This is because =1.

[0090] To obtain a specific order L in the direction of the spiral branch of the spiral undulation, the first partial wave f W1 The order of circumferential waviness of (φ,r') M W,1 and the second partial wave f W2 The order of circumferential waviness of (φ,r') M W,2 The following must apply:

number

number

number

[0091] [Table 5]

[0092] First partial wave f W1 (φ, r') has a wavefront with a negative slope (Fig. 6B), and the second partial wave f W2 (φ,r') has a wavefront with a positive slope (FIG. 6C). Specifically, the following applies to the pattern in FIG. 6A:

number

number

[0093] 7A to 7C show schematically how the spiral branches can be arranged on the dressing flank surface 331 of the dressing tool 33. FIG. 7A shows the case where just one spiral branch S1 is formed on the dressing flank surface 331, i.e., i s =1.

[0094] In FIG. 7B, two spiral branches S1, S2 are formed on the dress flank surface 331, i.e., i s = 2. Here, the spiral branches S1, S1 are offset in the circumferential direction by an offset angle Δφ, which in this example corresponds to π.

[0095] In FIG. 7C, three spiral branches S1, S2, and S3 are formed, i.e., s = 3. Here, the spiral branches S1, S2, S3 are offset in the circumferential direction by an offset angle Δφ, which is equal to 2π / 3.

[0096] 7D and 7E show another example pattern using a specific number. In this example, the number of spiral branches is i s = 2, and the radial wavelength is λ r’ = 15 mm, the pattern period is Δr' = 30 mm, the order of the spiral branch direction is L = 50, and the spiral branches S1 and S2 extend counterclockwise. The spiral waviness has an amplitude A = 3.5 μm.

[0097] Therefore, the order of the waviness in the circumferential direction of the first partial wave 1 and the second partial wave 2 is calculated using the following equation:

number

number

number

number

number

[0098] A pattern f(φ,r') with two spiral branches S1, S2 according to this formula is shown in Figure 7D. Figure 7E shows a portion of the pattern of Figure 7D as the dress flank modification f(φ,r) projected onto the annulus. Here, the pattern extends over a profile height d<Δr', where d=20 mm. Also, f(φ,r)=f(φ,r'+r A ) applies, where r A =30mm.

[0099] [Manufacturing of dressing tools] The dressing tools with the dressing flank modifications described above can be manufactured by a positive process or by a negative process.

[0100] [Positive Process] In the positive process, a substrate, preferably made of steel, is provided which is coated with hard material particles, typically diamond particles, preferably by electroplating. Methods for producing substrates with hard material particle coatings by the positive process are known from the prior art, for example from EP 2535145 and EP 2835220, the disclosures of which are incorporated herein by reference in their entirety.

[0101] 8A shows a schematic diagram of a conditioning device 50 according to an embodiment of the present invention. The conditioning device includes a dressing tool 33 (shown here in cross section). The substrate 330 has a hollow cylinder that is clamped to the dressing spindle 32 and can be driven to rotate about a dressing rotation axis A. A circular disk with a dressing flank that tapers radially relative to the dressing rotation axis A extends around the hollow cylinder. Hard material particles applied to the dressing flank form a dressing flank surface 331. To provide the dressing flank surface 331 with dressing flank modifications, the dressing flank surface is machined by a conditioning tool 51. In the example shown here, this conditioning tool 51 is a thin conditioning disk that can rotate about a conditioning rotation axis K that extends parallel to the dressing flank to be machined and can move perpendicular to the dressing flank surface 331 and parallel to the conditioning rotation axis K. The conditioning disk preferably has an abrasive coating bonded to it hard material particles having a hardness equal to or greater than that of the hard material particles of the dressing tool coating. To generate the dress flank modification, the dressing tool is driven to rotate about a dressing rotation axis A, and the conditioning tool 51 is driven to rotate about a conditioning rotation axis K. The rotating conditioning disk is then fed into contact with the dress flank surface 331, thereby removing material from the dress flank surface 331. In the example shown in FIG. 8A, the infeed movement is parallel to the normal to the dress flank surface 331.

[0102] The infeed movement of the conditioning tool 51 or the resulting infeed position perpendicular to the dressing flank surface is adjusted to the rotation frequency f of the dressing tool to generate the desired waviness. A The feed frequency f K, during which a discrete or continuous axial conditioning movement along the conditioning rotation axis K can also be carried out. In order to obtain the desired circumferential wave-shaped dressing flank modification of order M, the following applies in particular:

number

[0103] Instead of a thin conditioning disk, the conditioning tool 51 can also have a ribbed periphery. Figure 8B shows an example of an enlarged cross section of a conditioning tool 51 having three conditioning ribs 511. The conditioning ribs 511 have a radial wavelength λ r’ Each conditioning rib 511 has a rounded head with a rounding radius corresponding to one-fourth of the dress flank diameter, and each conditioning rib 511 can generate a conditioning track on the dress flank surface.

[0104] Working Example: The generation of the dress flank corrections shown as examples in Figures 2-6A is described below.

[0105] Figure 2: Generating the dress flank correction: The wavefront on the developed ring is inclined at an inclination angle α with respect to the circumferential direction and can be generated as follows: The conditioning tool is positioned at a constant feed value in a direction perpendicular to the dressing flank surface. A continuous axial conditioning movement of the conditioning tool is generated at a constant axial speed along the conditioning rotation axis K during at least one revolution of the dressing tool 33 .

[0106] The continuous axial conditioning movement can be performed from the inside to the outside or from the outside to the inside in the radial direction of the dressing tool 33. The rotation frequency f of the dressing tool A For a constant α, an increase in the desired tilt angle α correlates with a constant increase in axial velocity.

[0107] In the case of the example shown in FIG. 2, the tilt angle α is chosen so that the wavefront projected onto the unfolded ring has a tilt corresponding to Δr′ / 2π, and therefore the axial speed is proportional to the rotational frequency f of the dressing tool. A For a fixed value of , we must have the following velocity components projected onto the radial direction of the dressing tool:

number

[0108] In the example shown in Figure 2, each rotation of the dressing tool generates a conditioning trajectory on the dressing flank surface that extends diagonally over the entire length of the developed ring. The conditioning trajectory corresponds to the wave trough (dark shading in Figure 2) and therefore corresponds to half the radial wavelength λ r’ To generate the other wave troughs shown in FIG. 2, the conditioning tool position is changed after each rotation of the dressing tool, but the conditioning tool rotates at a circumferential wavelength Δφ relative to the deployed annulus. U If a conditioning tool 51 having multiple conditioning ribs 511 is used to generate all the desired conditioning orbits in one revolution, no repositioning of the conditioning tool 51 is required.

[0109] Figure 3: Generating the dress flank correction: In Figure 3, the wave-shaped dressing flank modification has a wavefront that is oriented in the radial direction when projected onto the annulus. To generate this dressing flank modification, the infeed position of the conditioning tool is adjusted in a direction perpendicular to the dressing flank surface by the rotation frequency f of the dressing tool. A The feed frequency fK During this process, no axial conditioning movement along the conditioning rotation axis K is performed. To obtain the desired circumferential wave-shaped dress flank modification of order M, the following relationship must be satisfied:

number

[0110] Depending on the profile height d of the annulus over which the dressing flank modifications are to extend and depending on the width of the individual conditioning tracks, the position of the conditioning tool must be changed at several different positions along the conditioning rotation axis K. To ensure that radially adjacent conditioning tracks form continuous wave fronts that extend in a straight radial direction, each time the conditioning tool is positioned at a new position, it must be ensured that the vibration infeed movement of the conditioning tool has a phase position synchronized with the rotation of the dressing tool 33, so that the waviness of the new conditioning track is in phase with the waviness of the previously generated conditioning track.

[0111] Alternatively, instead of changing the position of the conditioning tool along the conditioning rotation axis after each rotation of the dressing tool, it is also conceivable to generate a continuous axial conditioning movement of the conditioning tool at a constant axial speed along the conditioning rotation axis K. However, to ensure that an essentially straight wave front is formed in the radial direction, the axial speed must be selected such that the conditioning tool covers a distance along the conditioning rotation axis K at most that corresponds to the width of the conditioning orbit after one rotation of the dressing tool.

[0112] Figure 4: Generation of dress flank corrections: The dressing flank modification shown in FIG. 4 can be generated by positioning the conditioning tool at a constant infeed value in a direction perpendicular to the dressing flank surface, where no continuous axial conditioning movement along the conditioning rotation axis K is performed (in contrast to generating the dressing flank modification in FIG. 2), thereby generating a conditioning trajectory parallel to the circumferential direction. After the dressing tool has rotated at least one time, the position of the conditioning tool is changed to multiple different positions along the conditioning rotation axis K to generate new radially adjacent conditioning trajectories, thereby generating wavefronts that, when projected onto the unfolded annulus, extend in straight lines parallel to the circumferential direction. If a conditioning tool 51 having multiple conditioning ribs 511 is used to generate all desired conditioning trajectories in one rotation, the position change of the conditioning tool 51 may be omitted.

[0113] Figure 5: Generation of dress flank correction: The dressing flank modification shown in Figure 5 can be generated by superimposing the steps required to generate the dressing flank modifications shown in Figures 3 and 4. To generate the dressing flank modification shown in Figure 5, the infeed position of the conditioning tool is rotated in a direction perpendicular to the dressing flank surface at the rotational frequency f of the dressing tool. A The feed frequency f K oscillates at a constant velocity, without simultaneous axial conditioning movement along the conditioning rotation axis K. To obtain the desired circumferential wave-shaped dress flank modification of order M, the following relationship must be satisfied:

number

[0114] After one rotation of the dressing tool 33, each half of the radial wavelength λr’ To generate new conditioning orbits having a width of 1 / 2 and adjacent in the radial direction, the position of the conditioning tool 51 is changed to multiple different positions along the conditioning rotation axis K. As a result, circumferential undulations are formed along circumferential paths U1, U2 extending parallel to the circumferential direction. The vibration infeed movement of the conditioning tool has a phase position synchronized with the rotation of the dressing tool 33 so that the resulting circumferential ripples are shifted 180° from each other. If a conditioning tool 51 having multiple conditioning ribs 511 is used to generate all desired conditioning orbits in one rotation, the change in position of the conditioning tool 51 may be omitted.

[0115] Generating the dress flank correction for Figure 6A: To produce the dressing flank modification shown in FIG. 6A, a continuous axial conditioning movement of the conditioning tool along the conditioning rotation axis K is also produced at a constant axial speed over at least one revolution of the dressing tool 33, as in the case of the dressing flank modification of FIG. 2, but the conditioning tool is not set to a constant feed-in value in the direction perpendicular to the dressing flank surface (in contrast to the situation in FIG. 2), instead the feed-in position of the conditioning tool is varied in the direction perpendicular to the dressing flank surface with the rotation frequency f of the dressing tool. A The feed frequency f K As a result, a dress flank modification is obtained in which adjacent wave troughs and wave crests are arranged circumferentially along a spiral-shaped helical branch S1 on the ring, and the helical branch S1 forms a straight line on the unfolded ring that is inclined relative to the circumferential direction. To obtain a desired wave-like dress flank modification of order L in the direction of the spiral branch, the following relationship must be satisfied:

number

number

[0116] Of course, the steps used to generate the described examples may be combined to generate other dress flank modifications not explicitly illustrated herein.

[0117] In particular, patterns in which successive wave troughs intersect at any given angle are also conceivable. For example, a purely radially aligned wave trough may intersect a purely circumferentially aligned wave trough at a 90° angle when projected onto the annulus. Alternatively, the intersecting wave troughs may extend obliquely across the surface of the dress flank.

[0118] Dressing tool rotation frequency f A and / or the feeding frequency f of the conditioning tool K And / or the axial conditioning movement may be varied over time during machining to create special dress flank modifications with more complex patterns.

[0119] [Negative Process] Alternatively, dressing tools with the above-mentioned dressing flank modifications can also be manufactured using a negative process. For this, a negative substrate, preferably made of aluminum or graphite, is provided and bored into the negative shape of the desired dressing tool using a lathe boring tool. Negative processes for the manufacture of dressing tools are known from the prior art, for example from EP 1 110 671 A1, the disclosure of which is incorporated herein by reference in its entirety.

[0120] To obtain a desired dressing flank modification on the dressing flank surface 331, a corresponding negative modification can be intentionally bored into the negative die. FIG. 9 shows a schematic cross-sectional view of a negative die 60, where the negative die 60 is mounted for rotation about a negative die rotation axis D and has an inner flank 61 that tapers radially outward relative to the negative die rotation axis D. FIG. 9 also shows a schematic diagram of a lathe cutting tool 70, which is inserted into the negative die 60 and has a lathe cutting tool tip 71 that protrudes radially relative to the negative die rotation axis D. The lathe cutting tool tip 71 allows the negative die to rotate about the negative die rotation axis D at a rotation frequency f N During rotation at , material is removed from the inside flank 61, creating a negative modification.

[0121] By superimposing axial movement of the lathe cutting tool tip 71 along the negative rotation axis D and radial movement relative to the negative rotation axis D, the lathe cutting tool tip 71 can move along at least one entire inner flank 61.

[0122] The axial movement of the lathe cutting tool tip 71 along the negative rotation axis D is expressed as the lathe cutting tool frequency f D By oscillating at a rotation frequency f (schematically shown by the sinusoidal curve in FIG. 9), a negative trajectory is cut into the negative die, which exhibits a circumferential waviness in the circumferential direction corresponding to the negative impression of the desired dress flank modification of the dressing tool manufactured using this negative die. N and lathe cutting tool frequency f Dmay be constant over time or may vary over time. Similar to the above-described example of direct machining of the dress flank with a conditioning tool, all dress flank modifications shown as examples in Figures 2 to 6A and further variations thereof can be produced by corresponding superposition of axial and radial movements of the lathe cutting tool tip 71 relative to the negative die rotation axis D and corresponding synchronization with the rotation of the negative die 60.

[0123] Lathe cutting tool frequency f D and / or the negative rotation frequency f N And / or the axial and / or radial infeed movement of the lathe cutting tool tip along the inside flank 61 may be varied over time during machining to produce special dress flank modifications with more complex patterns.

[0124] Alternatively or additionally, the intentional creation of a negative modification may include the intentional creation of a negative tension, as will be described below with reference to Figures 10A and 10B.

[0125] FIG. 10A shows a schematic cross-sectional view of a negative die 60 with a lathe cutting tool 70. In this embodiment, a deformation device 80 is attached to the negative die 60 and deforms it. In the example shown, the deformation device 80 applies a force to the negative die 60 in the axial direction relative to the negative die rotation axis D, slightly compressing the negative die 60. As a result, regions of the inside flank 61 move axially closer to each other. When these regions of the inside flank 61 are pressed toward each other and pass the fixed lathe cutting tool tip 71 during rotation of the negative die, more material is removed from these regions than from other regions of the negative die 60 that are not compressed by the deformation device 80. The deformation device 80 preferably has force application regions periodically arranged around the circumference of the negative die. To generate forces in these force application regions, the deformation device 80 can have, for example, mechanical or hydraulic tensioning elements. In particular, forces can be applied directly to the force application regions by screws. Similarly, forces in the force application regions can be generated by hydraulic pistons. Alternatively or additionally, the deformation device may include a two-part device that at least partially surrounds the negative mold and is held together by screws and / or hydraulic pistons. In the released state (FIG. 10B), the negative mold has a negative trajectory with circumferential undulations, and wave troughs are generated in the negative mold when force is applied by the deformation device 80. These wave troughs in the negative mold 60 correspond to wave crests on the dressing flank surface of a dressing tool produced using this negative mold.

[0126] Of course, the use of the deformation device may be combined with the use of a lathe cutting tool tip 71 moving relative to the negative die to produce any negative / dress flank correction.

[0127] [Dressing of grinding worm] The present invention also includes a method for dressing a grinding worm 16 for generating a pre-toothed workpiece, in which a dressing modification of a dressing tool 33 is transferred onto a grinding worm flank 161 of the grinding worm, and a worm modification is generated on the grinding worm flank 161. The dressing tool 33 and the grinding worm flank 161 are in line contact.

[0128] FIG. 11 shows the annular projection of the ground worm flank 161 in a plane perpendicular to the worm rotation axis B in a developed form. The annular projection is formed by dividing the worm circumferential direction by the worm circumferential coordinate φ S The worm radial direction is defined as the worm radial coordinate r S As specified in.

[0129] 11. The worm modification in the form of three spiral branches S1', S1", S1'" is shown schematically on the developed grinding worm flank 161. The three spiral branches S1', S1", S1'" on the grinding worm flank 161 correspond to the same spiral branch S1 on the dressing flank surface 331, but are transferred to the grinding worm flank 161 at different rotational speed ratios between the dressing tool 33 and the grinding worm. The dashed arrows shown in FIG. 11 point in the direction of increasing rotational speed ratio between the dressing tool 33 and the grinding worm. As the rotational speed ratio increases, the transferred spiral branches S1', S1", S1'" extend at a steeper angle on the grinding worm flank 161. The worm modification generated by transferring the dressing flank modification to the grinding worm flank 161 has a number of wave periods per revolution of the grinding worm, which number is referred to here as the worm waviness order L. S By varying the rotational speed ratio between the dressing tool 33 and the grinding worm, the worm waviness order L S As the rotational speed ratio increases, the worm waviness order L S Typically, the speed ratio is between 10 and 60.

[0130] The rotational speed ratio may be constant over time or may be changed during dressing of the grinding worm, but if it is changed, the transferred spiral branch S1' will no longer form a straight line on the developed grinding worm flank, but will bend (if the rotational speed ratio changes suddenly) or curve (if the rotational speed ratio changes continuously).

[0131] Depending on the elevation height of the spiral branch S1 above the dressing flank surface 33 and the profile height d to which the spiral branch S1 extends above the dressing flank surface 33, multiple rotations of the dressing tool are required to transfer the complete spiral branch S1 onto the grinding worm flank 161. The closer the elevation height is to flat, the more rotations are required.

[0132] Therefore, a desired worm modification can be defined on the grinding worm flank 161 of the worm thread of the grinding worm 16, which can be back-calculated into a corresponding dressing flank modification for a selected fixed rotational speed ratio between the dressing tool 33 and the grinding worm, and the corresponding dressing flank modification can then be intentionally generated according to the manufacturing method described above.

[0133] [Generating targeted tooth surface modifications for pre-toothed workpieces] The worm modifications produced by the dressing tool described above can be transferred to the tooth flank of the pre-toothed workpiece in the gear generating process.

[0134] The generating process is carried out on a generating grinding machine 1, shown by way of example in FIG. 12, which will hereinafter also be referred to as the "machine" for short. The machine 1 has a machine bed 11, on which a tool carrier 12 is guided for displacement along a radial feed direction X. The tool carrier 12 holds an axial slide 13, which is guided for displacement relative to the tool carrier 12 along a feed direction Z. A grinding head is mounted on the axial slide 13 and can pivot about a pivot axis (the so-called A-axis) extending parallel to the X direction in order to adapt to the helix angle of the gear mechanism to be machined. The grinding head also holds a shift slide 14, on which a tool spindle 15 can move relative to the grinding head along a shift direction Y. A worm-shaped profiled grinding wheel (grinding worm) 16 is mounted on the tool spindle 15. The grinding worm 16 is driven to rotate about a worm axis B by the tool spindle 15 .

[0135] The machine bed 11 further holds a swiveling workpiece carrier 20 in the form of a turret, which can be swiveled about a swivel axis C3 between at least three positions. Two identical workpiece spindles are mounted diametrically opposite each other on the workpiece carrier 20, only one of which, workpiece spindle 21, is visible in FIG. 1. A workpiece can be clamped on each of the workpiece spindles and driven to rotate about the workpiece axis. The workpiece spindle 21 visible in FIG. 1 can be driven about the workpiece axis C1 and is in a machining position, in which a workpiece 23 clamped on the workpiece spindle 21 can be machined using a grinding worm 16. The other workpiece spindle, offset 180° and not visible in FIG. 1, is in a workpiece exchange position, in which a finished workpiece can be removed from this spindle and a new blank can be mounted on it. A dressing device 30 is mounted at a position offset 90° relative to the workpiece spindles.

[0136] Machine 1 has a number of moving components, such as slides or spindles, that are controllably movable by corresponding drives. These drives are often referred to in the art as "NC axes," "machine axes," or simply "axes." In some cases, this term also includes components, such as slides or spindles, that are driven by drives.

[0137] The machine 1 also has a number of sensors. By way of example, only two sensors 18 and 19 are shown diagrammatically in Fig. 12. Sensor 18 is a vibration sensor that detects vibrations of the housing of the grinding spindle 15. Sensor 19 is a position sensor that detects the position of the axial slide 13 relative to the tool carrier 12 along the Z direction. However, the machine 1 also comprises a number of other sensors. These sensors include, in particular, a further position sensor that detects the actual position of each linear axis, a rotation angle sensor that detects the rotational position of each rotary axis, a current sensor that detects the drive current of each axis, and a further vibration sensor that detects vibrations of each driven component.

[0138] All driven axes of the machine 1 are digitally controlled by a machine controller 40. The machine controller 40 comprises several axis modules 41, a control computer 42 and a control panel 43. The control computer 42 receives operator commands from the control panel 43 and sensor signals from various sensors on the machine 1 and uses these to calculate control commands for the axis modules 41. The control computer 42 also outputs and displays operating parameters on the control panel 43. The axis modules 41 each provide a control signal for one machine axis at a respective output.

[0139] A monitoring device 44 is connected to the control computer 42 and performs various monitoring tasks during operation of the machine 1 .

[0140] Figure 13 shows an enlarged view of a portion of Figure 1. The dressing device 30 can be seen particularly clearly here. A dressing spindle 32, to which a disk-shaped dressing tool 33 is clamped, is arranged on a swivel drive 31 and can be swiveled about a swivel axis C4. The dressing tool 33 is provided with an intentionally generated dress flank correction.

[0141] In a worm drive, as with the combination of an externally toothed spur gear (pre-toothed workpiece 23) and a grinding worm, point contact occurs when the axis of the pre-toothed workpiece 23 and the axis of the grinding worm 16 are not parallel. When rolling through this combination, the contact point moves on the tooth flank of the pre-toothed workpiece 23 and the grinding worm flank 161 of the grinding worm 16 along a path that is geometrically determined by the combination. In this context, the path on the tooth flank is called the contact track, and the path on the grinding worm flank is called the worm contact path.

[0142] In one embodiment of a method for generating a modified surface structure on the tooth flank of a pre-toothed workpiece 23, the grinding worm 16 is first dressed using the dressing tool 33 having a spiral undulation along a spiral branch S1 and the dressing method described above. In this case, the rotational speed ratio between the dressing tool 33 and the grinding worm is selected so that the spiral undulation is accurately reproduced along the worm contact path predetermined by the combination of the pre-toothed workpiece 23 to be machined and the grinding worm 16. In other words, the rotational speed ratio is selected so that the spiral branch S1' imprinted on the grinding worm flank 161 follows the worm contact path. This worm modification in the form of a worm undulation along the spiral branch S1' is then intentionally transferred to the tooth flank of the pre-toothed workpiece 23. For this purpose, the grinding worm 16 is driven to rotate about the worm axis B, and the pre-toothed workpiece 23 is driven to rotate about the workpiece axis C1, so that the grinding worm and the pre-toothed workpiece are in rolling engagement. In addition, both a movement of the grinding worm 16 relative to the pre-toothed workpiece 23 in a shift direction Y parallel to the worm axis B and an axial movement of the grinding worm 16 parallel to the workpiece axis C1 are generated here. The diagonal ratio of the axial movement of the grinding worm and the movement in the shift direction Y is selected so that the worm waviness is intentionally transferred onto the tooth flank of the pre-toothed workpiece, thereby intentionally modifying the surface structure of the tooth flank.

[0143] Therefore, a desired tooth flank modification can be defined on the tooth flank of the pre-toothed workpiece 23, which tooth flank modification can be back-calculated into a corresponding worm waviness along the spiral branch S1' on the grinding worm flank 161 for a selected diagonal ratio, and the worm waviness can then be back-calculated into a corresponding dress flank modification for a selected rotational speed ratio, and the corresponding dress flank modification can be intentionally generated according to the manufacturing process described above. [Explanation of symbols]

[0144] 1 Generating grinder 11 Mechanical Bed 12 Tool Carrier 13 Axial slide 14 Shift Slide 15 Tool Spindle 16 Grinding worm 161 Grinding worm flank 18 Acoustic Sensor 19 Position Sensor 20 Work Career 21 Work Spindle 211 Work spindle drive unit 23 Work 30 Dressing device 31 Swivel drive unit 32 Dress Spindle 33 Dressing Tools 330 Base 331 Dress Flank Surface 40 Machine Controller 41 axis module 42 Control Computer 43 Control Panel 44 Monitoring equipment 50 Conditioning Device 51 Conditioning Tools 511 Conditioning Rib 52 Conditioning Spindle 53 Conditioning control section 60 Negative type 61 Inside flank 70 Lathe Cutting Tools 71 Lathe cutting tool tip 80 Transformation Device A Dressing rotation axis B Worm shaft C1 Work axis C3 Swivel Axis C4 Swivel Axis X feed direction Y shift direction Z feed direction K Conditioning Rotating Shaft D Negative rotary axis R radial coordinate r' Radial coordinate of the pattern rectangle φ angular coordinate φ S Worm circumferential coordinate r S Worm radial coordinate λ r’ radial wavelength Δφ U Offset Angle a Tilt angle d profile height r A Inner diameter R1, R2 radial paths U1, U2 Circumferential route S1, S2, S3 spiral branches

Claims

1. A dressing tool for dressing a grinding worm (16) for creating teeth on a pre-toothed workpiece (23), The dressing tool (33) is configured to rotate around a dressing rotation axis (A) and has a dressing flank surface (331) that forms a ring in a projection plane perpendicular to the dressing rotation axis (A), wherein the radial direction of the ring is defined by radial coordinates (r) and the circumferential direction is defined by angular coordinates (φ), The dress flank surface (331) is provided with a deliberately generated dress flank correction, and the dress flank correction projected onto the ring can be represented as a two-dimensional Fourier series according to the radial coordinate (r) and the angular coordinate (φ). The dressing tool, characterized in that the Fourier series has at least one non-zero Fourier coefficient for a circumferential frequency component that is non-zero with respect to the angular coordinate (φ).

2. The dressing tool according to claim 1, wherein the dressing flank correction has a 2π periodicity with respect to the angular coordinate (φ).

3. The dressing tool according to claim 1 or 2, wherein the Fourier series has no non-zero Fourier coefficients for non-zero radial frequency components in the radial direction, and the intentionally generated dressing flank correction is wave-shaped with respect to the circumferential direction and has a wavefront in the form of a constant-phase line that is radially oriented when projected onto the ring.

4. The dressing tool according to claim 1, wherein the two-dimensional Fourier series has at least one non-zero Fourier coefficient for non-zero radial and circumferential frequency components, and the dressing flank modification projected onto the ring forms a chessboard-like structure having wave crests and wave troughs arranged offset from each other like a chessboard.

5. The dressing tool according to claim 4, wherein the chessboard-like structure is oriented such that the troughs and crests of waves adjacent to each other in the circumferential direction are arranged along spiral branches (S1, S2, S3) extending spirally on the ring.

6. A method for manufacturing the dressing tool (33) described in claim 1 or 2, The coated substrate of the dressing tool (33) is manufactured in a positive process, A conditioning tool (51), in particular a rotating conditioning disc perpendicular to the dress flank surface, is used to intentionally create the dress flank correction. The method, including the method described above.

7. Intentionally generating the aforementioned dress flank modification is The dressing tool (33) is driven to rotate around the dressing rotation axis (A), The conditioning tool (51) is driven to rotate around the conditioning rotation axis (K) of the conditioning tool (51), The conditioning tool (51) is moved relative to the dressing tool (33) in a direction having a component perpendicular to the dressing flank surface, thereby removing material from the dressing flank surface (331) to produce the dressing flank correction. The method according to claim 6, including the method described in claim 6.

8. A method for manufacturing a dressing tool (33) according to claim 1 or 2, wherein the method is: To manufacture the dressing tool (33) in a negative process. The negative process includes, A negative type (60) is manufactured by boring out a negative substrate. To intentionally perform a negative correction by boring out the boring negative type (60) so that the negative correction results in the dress flank correction, and / or, During the boring process, tension is generated mechanically and / or hydraulically in the negative substrate, and after the tension is released, the boring negative type (60) has a negative correction that results in the dress flank correction. The method, including the method described above.

9. A method for dressing a grinding worm (16) for creating teeth on a pre-toothed workpiece, Dress the grinding worm (16) using the dressing tool (33) described in claim 1, such that the dressing flank correction results in a worm correction on the grinding worm flank (161) of the worm threads of the grinding worm (16). The method, including the method described above.

10. The method according to claim 9, wherein a predetermined fixed rotation angle coupling exists between the dressing tool (33) and the grinding worm (16) in order to intentionally generate periodic worm corrections on the grinding worm flank (161) along the worm threads.

11. The method according to claim 9, wherein a predetermined time-variable rotation angle coupling exists between the dressing tool and the grinding worm (16) in order to intentionally generate aperiodic worm correction on the grinding worm flank (161) along the worm threads.

12. A method for dressing a grinding worm (16) for creating teeth on a pre-toothed workpiece (23), To define a desired worm modification on the grinding worm flank (161) of the worm thread of the grinding worm (16), With respect to a selected fixed or variable rotation angle coupling between the dressing tool (33) and the grinding worm (16), the corresponding dressing flank correction of the dressing tool (33) is calculated by working backward from the desired worm correction. The method described in claim 6 is used to manufacture the dressing tool (33) having the corresponding dressing flank modification, The dressing tool (33) is used to dress the grinding worm (16) by the selected fixed or variable rotation angle coupling, wherein the dressing flank correction generates the desired worm correction along the worm threads. The method, including the method described above.

13. A method for generating a modified surface structure on the tooth surface of a pre-toothed workpiece (23), The method described in claim 9 provides for dressing a grinding worm suitable for creating teeth on a pre-toothed workpiece (23), The grinding worm (16) is driven to rotate around the worm shaft (B), The pre-toothed workpiece (23) is driven to rotate around the workpiece axis (C1), A relative movement between the grinding worm (16) and the pre-toothed workpiece (23) is generated at a shift feed rate in the shift direction (Y) parallel to the worm axis, To generate relative movement between the grinding worm and the pre-toothed workpiece at an axial feed rate in an axial direction parallel to the workpiece axis (C1), Includes, The grinding worm (16) and the pre-toothed workpiece (23) are engaged by rolling, and the shift feed rate and the axial feed rate are in a predetermined diagonal ratio such that the worm modification is transferred onto the tooth surface of the pre-toothed workpiece (23), thereby intentionally modifying the surface structure of the tooth surface.

14. The dressing tool is the dressing tool (33) described in claim 5, wherein during dressing, there exists a predetermined fixed rotation angle coupling between the dressing tool (33) and the grinding worm (16) selected such that the helical branch (S1) is mapped onto the worm contact path, The method according to claim 13, wherein the worm contact path corresponds to a line along which the contact point between the rolling-engaged grinding worm (16) and the pre-toothed workpiece (23) moves on the grinding worm flank during the generation process.

15. A conditioning tool (51) attached to a conditioning spindle (52), A dress spindle (32) is configured to receive a dress tool (33) that rotates around a dress rotation axis (A), A conditioning control unit (53) is configured to move the conditioning tool (51) relative to the dressing tool (33) so that the dressing tool (33) is provided with the dressing flank correction described in claim 1 or 2, A conditioning device equipped with [the following features].

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