Methods of grinding and polishing gears

Abstract

A method for grinding and polishing the tooth flank surface (40) of the teeth (50) of a gear (60) includes the following steps: a) providing a grinding device (6), a polishing device (7), a dynamic positioning device (8), and a gear (60); b) having the grinding device (6) grind the gear (60); c) removing the gear (60) from the grinding device (6); d) having the dynamic positioning device (8) contact the tooth flank surface (40) with a polishing body (80) of the polishing device (7) to polish the tooth flank surface; e) having the dynamic positioning device (8) dynamically adjust the position and orientation of the gear (60) relative to the polishing body (80), or having the dynamic positioning device (8) dynamically adjust the position and orientation of the polishing body (80) relative to the gear (60) such that the tooth flank surface is polished by the polishing body. The dynamic positioning device (8) may be a robot.

Description

Technical Field

[0001] This disclosure relates to a method for grinding and polishing gears. Background Technology

[0002] In an era of climate change, vehicles should emit less carbon dioxide and produce less noise throughout their lifespan. If the gears in a vehicle's transmission have smoother tooth flank surfaces where they contact other gears and transmit torque, the transmission will produce less noise and can run for more years and kilometers. In manufacturing, gears are ground into their final shape on a grinding machine.

[0003] U.S. Patent 4,850,155 describes a conventional method for machining gears that uses a generally involute worm-shaped tool to produce a lateral convex surface, the effective length of which is greater than the length of the working area, and the distance from the center of the worm to the gear varies during its feed motion in both axial and tangential diagonal directions. U.S. Patent 9,718,139 B2 describes a tool for grinding toothed workpieces.

[0004] In applications requiring polishing, some traditional grinders comprise both a grinding zone and a polishing zone. After grinding the gear and its teeth, the tooth flanks are polished to the desired surface smoothness on the same grinder. An example is the use of a so-called dual-wheel grinder / polisher, a dual-zone grinder for worm gears with both grinding and polishing zones. Polishing the gear on such a machine typically takes longer than grinding it. Grinding and polishing the gear on the same machine can double the processing time compared to grinding only the gear.

[0005] This traditional grinder is not designed to grind the second gear while polishing the first gear; therefore, the grinder is occupied by the first gear while the first gear is being ground and polished.

[0006] Grinding machines are expensive pieces of equipment. In order to use them in the most economical and efficient way, the gears should occupy the grinding machine for as little time as possible. Summary of the Invention

[0007] This disclosure attempts to address this need. In a first basic aspect, this disclosure provides a method for grinding and polishing the tooth flank surface of a first gear, the method comprising the following steps in sequence:

[0008] a) Provides a rotating grinding apparatus for grinding a first portion and a second portion of the tooth flank surface of a first gear; provides a polishing apparatus including a fixed shaft and a polishing body rotatable about the fixed shaft, the polishing body being adapted to polish the tooth flank surface of a gear; provides a dynamic positioning device for holding the gear and for dynamically adjusting the position and orientation of the gear relative to the fixed shaft during polishing; and provides a first gear;

[0009] b) The grinding device grinds the first and second portions of the tooth flank surfaces of the first gear.

[0010] c) Remove the first gear from the grinding device;

[0011] d) The dynamic positioning device brings the first part of the tooth flank surface into contact with the rotating polishing body, so that the first part of the tooth flank surface is polished by the polishing body;

[0012] e) The dynamic positioning device dynamically adjusts the position and orientation of the first gear relative to the fixed shaft, so that the second part of the tooth side surface is polished by the polishing body.

[0013] Performing the polishing portion of this method on a separate device allows the second gear to be ground on a grinding device while the first gear is polished on a separate polishing device. Polishing devices are generally cheaper than grinding machines, so their usage is usually less critical. Furthermore, the use of dynamic positioning devices provides greater flexibility in adjusting the gear position and orientation during polishing than during polishing on a conventional grinding machine.

[0014] Gear grinding is typically performed on grinding machines purchased from companies such as Liebherr, Reishauer, Kapp-Niles, and Samputensili. Grinding wheels (such as, for example, 3M) are used. TM Ceramic grinding wheels 22VD, 3M TM Ceramic grinding wheels 33VB or 3M TM Cubitron TM II ceramic grinding wheels 92VJ (all purchased from 3M Company, St. Paul, Minnesota, USA) can be used for grinding.

[0015] As used herein, the term "polishing" refers to polishing using bonded abrasives (such as, for example, a polishing pad). Suitable polishing materials for the methods according to this disclosure include, for example, Artifex A800 PL6966 polyurethane adhesive from Artifex, Kaltenkirchen, Germany, or 3M Company of St. Paul, Minnesota, USA. TM Scotch-Brite DB-WL 7S Fine-grained Disk.

[0016] Polishing typically provides a smoother surface than grinding. Polishing the surface portion of the tooth flank after grinding provides a smoother surface within the surface portion, meaning it is smoother than the surface portion after grinding. A smoother surface can transmit torque to adjacent gears with less friction loss and lower noise levels, and generally provides longer gear life.

[0017] According to this disclosure, the gear can be, for example, a paddle shifter, pinion, sprocket, crown gear, bevel gear, or any other type of gear, such as those used in vehicle transmissions or wind turbine transmissions. The method according to this disclosure is particularly well-suited for manufacturing gears for transmissions of heavy vehicles such as trucks, tractors, or construction vehicles. The high-quality surface obtained by using a dynamic positioning device in the polishing step helps to increase the contact surface between the teeth of opposing gears and reduce wear, thereby extending the service life of the gears.

[0018] Therefore, typically, in some embodiments of the method according to this disclosure, the first gear is a gear used in the gearbox of a heavy vehicle such as a truck, tractor, bus, long-distance bus, railway locomotive, or construction vehicle, or in the gearbox of a wind turbine. The first gear may also be a gear used in the gearbox of construction machinery or a crusher.

[0019] Gears used in the gearboxes of heavy vehicles such as trucks, tractors, or construction vehicles, or in the gearboxes of wind turbines, are typically large gears. They generally have an outer diameter of 100 mm or more, with some reaching 2 or 3 meters (e.g., in wind turbines). Some have a gear width of 20 mm or more, while others can be as wide as 200 mm or even 400 mm or more. Some of these gears are helical gears. Therefore, in some methods according to this disclosure, the first gear has a diameter of 100 mm or more, and / or the first gear has a weight of 1000 grams or more, and / or wherein the first gear has a gear width of 20 mm or more, and / or wherein the first gear is a helical gear.

[0020] In some implementations, the first gear is a gear made of steel or iron. It can be made of, for example, cast steel, gray cast iron, ductile iron, or cast iron. Steel and cast iron are common materials used for gears, and are reasonably priced and readily available.

[0021] Gear teeth have surfaces facing each other on the same gear. These surfaces are referred to herein as tooth flank surfaces. They typically extend radially away from the gear hub, opposite to the circumferential direction. As the gear rotates, portions of the tooth flank surfaces come into contact with portions of the corresponding tooth flank surfaces of the other gear, and mechanical forces and torques are transmitted between the gears via these tooth flank surfaces. Polishing the tooth flank surfaces of gears is beneficial for reducing noise in transmissions and extending the service life of the gears within them.

[0022] The grinding apparatus that can be used in the method according to this disclosure can be, for example, a stationary grinder, which is suitable for grinding gears used in the gearbox of a vehicle (e.g., a vehicle like a truck or tractor) or the gearbox of a wind turbine.

[0023] The grinding device can be, for example, a rotating grinding device. It may include a fixed rotating shaft, on which gears may be mounted for grinding.

[0024] Grinding apparatuses that can be used in the methods according to this disclosure may include grinding wheels or spiral grinding tools shaped and arranged to grind portions of the tooth flank surfaces of gear teeth, such as gears used in vehicle transmissions or wind turbine transmissions. Examples of such grinding apparatuses are the Holroyd GTG2, the Liebherr LGG280, or other grinding machines available from Liebherr, Klingelenberger, or Gleason.

[0025] The grinding apparatus is adapted to grind the tooth flank surfaces of the first gear to a surface roughness Rz of 3.5 micrometers or less. This surface roughness Rz is measured using the stylus method and an inductive sliding probe according to the DIN EN ISO 3274 standard, which came into effect on June 29, 2020, with a stylus radius of 5 micrometers and a apex cone angle of 60 degrees. For example, it can be measured using a MarSurf M300 instrument from Mahr GmbH, Göttingen, Germany. This surface roughness is typically sufficient to achieve acceptable processing time in subsequent polishing steps.

[0026] The polishing apparatus that can be used in the method according to this disclosure may be, for example, a benchtop grinder equipped with a rotating polishing body (e.g., a polishing disc or polishing wheel). The polishing apparatus and polishing body are adapted to increase smoothness and reduce the surface roughness of the tooth flanks that have been previously ground by the grinding apparatus.

[0027] According to this disclosure, the polishing apparatus is a separate device from the grinding apparatus. For example, it can move and / or operate independently of the grinding apparatus. It can operate at a speed independent of the operating speed of the grinding apparatus.

[0028] In some embodiments, the polishing apparatus is adapted to polish the tooth flank surface of the first gear to a surface roughness Rz of 1.2 micrometers or less, which is measured using a stylus method and an inductive sliding probe according to DIN EN ISO 3274 standard effective June 29, 2020, with a stylus radius of 5 micrometers and a apex cone angle of 60 degrees. Rz typically refers to the maximum height of the profile. This surface roughness is generally sufficient to achieve lower noise levels and acceptable gear life extensions by reducing frictional losses and associated wear. In some embodiments of these embodiments, the polishing apparatus is adapted to polish the tooth flank surface of the first gear to a surface roughness Rz of 1.2 micrometers or less and Ra of 0.2 micrometers or less. Ra is known to refer to the arithmetic mean difference of the profiles. Similarly, Rz and Ra can be determined using a MarSurf M300 instrument from Mahr GmbH, Göttingen, Germany.

[0029] In some embodiments of the method according to the first basic aspect of this disclosure, the polishing apparatus is a benchtop grinder. The benchtop grinder includes a fixed shaft and a polishing body for polishing a first gear positioned and oriented by a dynamic positioning device. The polishing body is mounted on the fixed shaft. Benchtop grinders are readily available and inexpensive, thus making gear manufacturing more economical. Embodiments according to the first basic aspect of this disclosure are preferred, particularly when the gear is sufficiently light to be reliably held, positioned, and oriented by a positioning device (such as a multi-axis robot).

[0030] The polishing body rotates about a fixed axis of the polishing apparatus and is adapted to polish the tooth flank surfaces of the gear teeth. The polishing body can be, for example, a polishing disc or deburring disc, or typically a grinding wheel or disc. In some embodiments, the polishing body is covered with a nonwoven material. Polishing bodies covered with nonwoven materials possess a degree of flexibility, and therefore can conform to the shape of the tooth flanks better than polishing bodies made of many other materials.

[0031] Polishing bodies suitable for certain gears are, for example, 3M. TMScotch-Brite DB-WL deburring wheel or Artifex A800 polyurethane bonded grinding wheel.

[0032] The polishing body is suitable for reducing surface roughness Rz to less than 1.2 micrometers (μm), or less than 1 μm, or less than 0.5 μm. The polishing body is suitable for reducing surface roughness Rz from greater than 2 μm to less than 1.2 μm.

[0033] According to the first basic aspect of this disclosure, the polishing body can rotate about a fixed axis, that is, the axis is fixed in position and orientation relative to the base of the polishing device, which is the opposite of the method according to the second basic aspect of this disclosure, in which the position and orientation of the rotating polishing body are dynamically adjusted.

[0034] A polishing body is suitable for polishing the tooth flank surfaces of gears. It can be adapted in this way, for example, by having a profile that allows it to mesh between two adjacent teeth of the gear, or by having a hardness, grain size, or composition that helps to polish the tooth flank surfaces of gears used in vehicle transmissions or wind turbine transmissions (which are typically made of steel or iron and have specific dimensions and profiles).

[0035] The dynamic positioning device is suitable for holding the gear during polishing on the polishing apparatus and for dynamically adjusting the position and orientation of the gear relative to a fixed shaft during polishing on the polishing apparatus. In this method, the polishing body can be rotatably mounted on the fixed shaft.

[0036] In the method of the second basic aspect of this disclosure, as explained below, the dynamic positioning device can be used to dynamically position a rotating polishing body and to dynamically adjust the position and orientation of the rotating polishing body relative to the gear during polishing on the polishing apparatus, the polishing body being adapted to polish the tooth flank surfaces of the gear teeth. In this method, the gear can be rotatably mounted on a fixed shaft.

[0037] In the method according to the first basic aspect, the dynamic positioning device may, for example, include an engagement device to engage with the center hole of the gear, or it may include a clutch, pliers, or clamps to clamp the gear securely enough to hold it during polishing on the polishing apparatus. The positioning device may be operable to hold the gear such that it can bring the gear into contact with the polishing body in a controlled manner required for successful polishing.

[0038] In some embodiments of the method according to this disclosure, the dynamic positioning device is a robot or a robot positioning device. A suitable robot is the KUKA KR 60 HA robot, available from KUKA AG, Augsburg, Germany. The dynamic positioning device can be a multi-axis robot or a multi-axis robot positioning device, such as a 5-axis robot or a 6-axis robot. Thus, in some methods according to the first basic aspect of this disclosure, the dynamic positioning device is a software-controlled robot comprising multiple segments and four, five, or six axes capable of rotating independently about these axes, thereby dynamically adjusting the position and orientation of the first gear by rotating one or more axes.

[0039] Generally, robots are considered particularly suitable as positioning devices in the methods according to this disclosure because they allow for very precise and very rapid dynamic adjustment of the position and orientation of gears or polishing bodies, i.e., they can be programmed to move gears (or move rotating polishing bodies along gears) along rotating polishing bodies with very precise speed and at the most suitable speed, so that all the required portions of the tooth flanks are polished uniformly with sufficiently high pressure for a sufficient length of time.

[0040] Dynamic adjustment of position and orientation refers to the ability to adjust these parameters continuously (or in very small steps, if digitized) as the gear is being polished. Therefore, adjacent surface portions of the tooth flanks can be polished during the continuous movement of the gear (or polishing body) without moving the gear and polishing body away from each other. This minimizes the time spent polishing all tooth flanks of the gear, thereby increasing productivity and achieving effective machine uptime.

[0041] To achieve high-precision polishing of the gear tooth flanks, equipping the positioning device with sensors to sense the contact force between the tooth flank surface and the polishing body may be advantageous. The positioning device can dynamically adjust its position and orientation in response to the sensor output, thereby optimizing the polishing process results. A sound sensor can be used to detect the contact between the polishing body and the gear. Therefore, in some methods according to this disclosure, the robot includes sensors for sensing the force or contact pressure exerted on the first gear by the polishing body and / or sensors for sensing sound, and the robot dynamically adjusts its position and orientation in response to the sensor output.

[0042] Regardless of the presence of a sensor in the positioning device, it may be advantageous to vary the contact pressure between the tooth flank surface and the polishing body when polishing a first portion of the tooth flank surface and then a second portion. More generally, it may be advantageous to vary the contact pressure when polishing different portions of the tooth. A tooth flank portion that will have less contact with the opposing gear during use may require less pressure during polishing than a portion that has more contact with it.

[0043] Therefore, in some methods according to this disclosure, the dynamic positioning device dynamically adjusts its position and orientation such that the second contact pressure when the second part is polished is different from the first contact pressure when the first part is polished.

[0044] As described above, an important aspect of this disclosure is that after the grinding step on the grinding apparatus, the gear is removed from the grinding apparatus without having to be polished on the grinding apparatus. Instead, the gear is polished on a separate polishing apparatus, which allows the grinding apparatus to quickly begin grinding a second, subsequent gear. Thus, the polishing of the first gear and the grinding of the second gear can be performed in parallel.

[0045] The gear can be mounted on a grinding device for grinding. After the grinding step on the grinding device, the gear can be removed from the grinding device without polishing it. Therefore, in some embodiments, step c of the above method can be step c: removing the first gear from the grinding device.

[0046] According to this disclosure, the grinding apparatus and the polishing apparatus are separate devices. Therefore, the polishing apparatus may have a rotating shaft for mounting gears thereon, which is separate from the rotating shaft of the grinding apparatus. The orientation of the rotating shaft of the polishing apparatus may differ from that of the rotating shaft of the grinding apparatus. The rotating shaft of the polishing apparatus may rotate at a speed independent of the rotational speed of the rotating shaft of the grinding apparatus. The polishing apparatus may be controlled by a different control instrument than the control instrument controlling the grinding apparatus.

[0047] In some methods according to this disclosure, the dynamic positioning device performs the step of removing the first gear from the grinding apparatus. Removing the gear from the grinding apparatus after the grinding step can be performed by the same positioning device, which can later hold and position the gear during a polishing step. Enabling the positioning device to remove the gear from the grinding apparatus is a typical task of the positioning device, enabling it to perform this task at a specific speed or with a specific precision.

[0048] Alternatively, the gears can be removed from the grinding device by a separate operating device or operator.

[0049] The contact between a portion of the tooth flank surface of the gear and the rotating polishing body is performed in such a way that the polishing body polishes the tooth flank surface during the contact.

[0050] In some embodiments, a second portion of the tooth flank surface of the first gear is polished by a rotating polishing body, which remains in contact with the first gear. In this embodiment, the polishing process can be a continuous process in which the polishing body is not removed from the gear. This continuous process can produce a smoother tooth flank surface and can be more efficient because it avoids the time loss required to remove the gear from the rotating polishing body and then back to it.

[0051] One advantage of the method according to this disclosure is that the expensive grinding apparatus is used only for grinding and not for polishing, thus its use is expensive only in the grinding process step, while the polishing process step is performed on a separate (usually cheaper) polishing apparatus. This separate processing facilitates the simultaneous processing of two gears: the first gear is polished on the polishing apparatus while the second gear is ground on the grinding apparatus. This parallel processing of the two gears produces economic benefits and can reduce the production cost of the gears.

[0052] Therefore, in some embodiments of the method according to this disclosure, a second portion of the tooth flank surface of the first gear is polished by a rotating polishing body, while a grinding device grinds a portion of the second gear.

[0053] While the first basic aspect of this disclosure relates to a method in which a polishing body is mounted on a fixed shaft and a dynamic positioning device adjusts the position and orientation of a first gear relative to a rotating polishing body to polish the gear, the benefits of performing polishing on a separate device can also be obtained by a method in which a first gear is mounted on a fixed shaft and a dynamic positioning device adjusts the position and orientation of a rotating polishing body to polish the tooth flanks of the first gear.

[0054] Therefore, in a second basic aspect, this disclosure also provides a method for grinding and polishing the tooth flank surface of a first gear, the method comprising the following steps in sequence:

[0055] a) Provides a rotating grinding apparatus for grinding a first portion and a second portion of the tooth flank surface of a first gear; provides a polishing apparatus comprising a rotating polishing body and a dynamic positioning device, the polishing body being adapted to polish the tooth flank surface of the gear, the dynamic positioning device being used to dynamically position the rotating polishing body and to dynamically adjust the position and orientation of the rotating polishing body relative to the gear during polishing; and provides a first gear;

[0056] b) The grinding device grinds the first and second portions of the tooth flank surfaces of the first gear.

[0057] c) Remove the first gear from the grinding device;

[0058] d) The dynamic positioning device brings the rotating polishing body into contact with the first part of the tooth flank surface, so that the first part of the tooth flank surface is polished by the polishing body;

[0059] e) The dynamic positioning device dynamically adjusts the position and orientation of the rotating polishing body relative to the first gear, so that the second part of the tooth side surface is polished by the rotating polishing body.

[0060] As described above, the features, advantages and benefits of the method according to the first basic aspect of this disclosure are correspondingly applicable to the method according to the second basic aspect.

[0061] In some methods according to the second basic aspect of this disclosure, the first gear is a gear used in the gearbox of a heavy vehicle such as a truck, tractor, bus, long-distance bus, railway locomotive or construction vehicle, or in the gearbox of a wind turbine.

[0062] In some methods according to the second basic aspect of this disclosure, the first gear has a diameter of 150 mm or greater, and / or the first gear has a weight of 1000 g or greater, and / or the first gear has a gear width of 30 mm or greater, and / or the first gear is a helical gear.

[0063] In some methods according to the second basic aspect of this disclosure, the first gear is a gear made of steel or iron.

[0064] In some methods according to the second basic aspect of this disclosure, the grinding apparatus is adapted to grind the tooth flank surface of the first gear to a surface roughness Rz of 3.5 micrometers or greater, which is measured using the stylus method and an inductive sliding probe according to DIN EN ISO 3274, which came into effect on June 29, 2020, with a stylus radius of 5 micrometers and a apex cone angle of 60 degrees.

[0065] In some methods according to the second basic aspect of this disclosure, the polishing apparatus is adapted to polish the tooth flank surface of the first gear to a surface roughness Rz of 1.2 micrometers or less, which is measured using a stylus method and an inductive sliding probe according to DIN EN ISO 3274, which came into effect on June 29, 2020, with a stylus radius of 5 micrometers and a apex cone angle of 60 degrees. Again, Rz generally refers to the maximum height of the profile. In some embodiments of these embodiments, the polishing apparatus is adapted to polish the tooth flank surface of the first gear to a surface roughness Rz of 1.2 micrometers or less and Ra of 0.2 micrometers or less. Ra refers to the arithmetic mean difference of the profile.

[0066] In some methods according to the second basic aspect of this disclosure, the polishing body may be, for example, a polishing disc or deburring disc, or typically a grinding wheel or grinding disc. In some methods according to the second basic aspect of this disclosure, the polishing body is made of a nonwoven material. In some embodiments of the second basic aspect of the invention, the polishing body is made of a nonwoven material.

[0067] In some methods according to the second basic aspect of this disclosure, the dynamic positioning device is a software-controlled robot comprising multiple segments and four, five, or six axes, which are capable of rotating independently about these axes, thereby dynamically adjusting the position and orientation of the polishing body by rotating one or more axes.

[0068] In some of these methods according to the present disclosure, the robot includes a sensor for sensing the force or contact pressure exerted on the first gear by the polishing body, and the robot dynamically adjusts its position and orientation in response to the output of the sensor. Alternatively or additionally, the robot may include an acoustic sensor for sensing the contact between the polishing body and the first gear. The robot may dynamically adjust its position and orientation in response to the output of the acoustic sensor.

[0069] In some methods according to the second basic aspect of this disclosure, the dynamic positioning device dynamically adjusts its position and orientation so that the second part is polished under contact pressure different from the contact pressure when the first part is polished.

[0070] In some methods according to the second basic aspect of this disclosure, the dynamic positioning device performs the step of removing the first gear from the grinding device.

[0071] In some methods according to the second basic aspect of this disclosure, a second portion of the tooth flank surface of the first gear is polished by a rotating polishing body, which remains in contact with the first gear.

[0072] In some methods according to the second basic aspect of this disclosure, a second portion of the tooth flank surface of the first gear is polished by a rotating polishing body, while a grinding device grinds a portion of the second gear. Attached Figure Description

[0073] The method according to this disclosure will now be described in more detail with reference to the following drawings, which illustrate specific embodiments of the prior art method and the method of the present invention:

[0074] Figure 1 A side view of the grinding and polishing station of a grinding machine performing a method of the prior art;

[0075] Figure 2 A side view of the grinding apparatus, polishing apparatus, and positioning apparatus performing the first method according to this disclosure; and

[0076] Figure 3 A side view of the grinding apparatus, polishing apparatus, and positioning apparatus performing the second method according to this disclosure. Detailed Implementation

[0077] Figure 1 A side view shows the grinding and polishing station of a grinding machine 5 performing a method known in the prior art. In this conventional method, a worm-shaped grinding wheel 10 and a worm-shaped polishing wheel 20 are arranged on the rotating shaft 30 of the conventional grinding machine 5. The grinding wheel 10 is shown as grinding the tooth flank surface 40 of the teeth 50 of a toothed gear 60.

[0078] Once the grinding of the tooth flank surface 40 is complete, the conventional grinding machine 5 moves the gear 60 from grinding position A in a direction parallel to the axis 30, indicated by arrow 70, to polishing position B. In grinding position A, the gear 60 is ground by the grinding wheel 10, and in polishing position B, the gear 60 is polished by the polishing wheel 20 to make the surface of the tooth flank 40 previously ground by the grinding wheel 10 smoother. The same gear 60 (drawn with a solid line in grinding position A opposite to the grinding wheel 10) is drawn with a dashed line in polishing position B to indicate its position after a period of grinding.

[0079] Traditional grinding machines (such as) Figure 1 The grinding machine 5 shown is not designed to process two gears 60 simultaneously. A hypothetical setup (where the first gear is polished by the polishing wheel 20 at polishing position B, while the second gear is ground by the grinding wheel 10 at grinding position A) is not applicable today, at least because the shaft 30 is shared by both the grinding wheel 10 and the polishing wheel 20. In order to grind the tooth flanks 40 using the grinding wheel 10, the shaft 30 moves back and forth linearly in a direction perpendicular to the plane of the drawing at a certain linear velocity, which is typically higher than the linear velocity required to polish the tooth flanks 40 using the polishing wheel 20.

[0080] Therefore, when gear 60 moves from grinding position A to polishing position B, and before the polishing process begins, the linear velocity of the linear movement of shaft 30 in the direction perpendicular to the plane of the attached drawing decreases.

[0081] Figure 2 A first method according to this disclosure is shown in a side view. The grinding apparatus 6 (e.g., as...) Figure 1 The grinding machine shown (such as grinding machine 5) includes a worm-shaped grinding wheel 10 arranged on the rotating shaft 30 of the grinding device 6. The grinding wheel 10 is shown for grinding the tooth flank surface 40 of the teeth 50 of the second toothed gear 61, similar to that for grinding the tooth flank surface 40 of the second toothed gear 61. Figure 1 Explanation of grinding position A in the diagram.

[0082] and Figure 1Unlike the prior art method shown, the grinding device 6 does not perform polishing on the tooth flank 40 of the second gear 61. Instead, the second gear 61 is removed from the grinding device 6, taken from the grinding device 6, and moved to a separate polishing device 7 outside the grinding device 6.

[0083] The polishing device 7 is a benchtop grinder 7, in which the polishing body 80 rotates around a fixed (i.e., fixed) axis 31. The polishing body 80 is a 3M product available from 3M Company of St. Paul, Minnesota, USA. TM Scotch-Brite TM DB-WL 7S Fine Deburring Wheel. Using this polishing body 80, a surface smoothness exhibiting an Rz of less than 1.0 micrometer and an Ra of less than 0.2 micrometer can be obtained on certain gears.

[0084] In order to polish the gear 60, the gear 60 is held by a positioning device 8, which makes some tooth flank surfaces 40 of the teeth 50 of the gear 60 contact the rotating polishing body 80.

[0085] The positioning device 8 is a software-controlled multi-axis robot 8, such as the KUKA KR 60 HA robot from KUKA AG, Augsburg, Germany. It comprises three segments 90 and six axes 100, with only two axes in... Figure 2 As can be seen, segment 90 can rotate independently about axis 100. This allows for great flexibility in positioning and adjusting the attitude of the first gear 60 relative to the rotating polishing body 80, thereby achieving high-quality polishing.

[0086] To fully polish the tooth flank surface 40, the robot 8 positions the gear 60 to fit the polishing body 80 for polishing a first portion of the specific tooth flank surface 40, and then continuously and dynamically adjusts the position and orientation of the gear 60 relative to the fixed axis 31 so that a second portion of the tooth flank surface 40 adjacent to the first portion is polished by the polishing body 80. This is performed on all portions of the tooth flank surface 40 that should be polished, as well as on all teeth 50 of the gear 60.

[0087] like Figure 2 As shown, the second gear 61 can be ground on the grinding device 6, while the first gear 60 is polished on the polishing device 7, having previously been ground on the grinding device 6. The grinding device 6 performs only grinding, allowing the execution time of the "grind-only" process for a single gear 60 and a single gear 61 to be significantly shorter than that of the grinding device 6. Figure 1 The traditional "grinding and polishing" process on the grinding machine 5 has a shorter execution time.

[0088] Although the grinding device 6 is a high-cost, high-precision machine, the polishing device 7, combined with the positioning device 8, is generally less expensive. Separating the lower-value polishing operations on the polishing device 7 from the higher-value grinding operations on the grinding device 6 optimizes the return on investment of the grinding device 6 and brings economic benefits.

[0089] In an alternative method according to this disclosure, the polishing body is mounted on a dynamic positioning device that polishes the fixed gear by dynamically adjusting the position and orientation of the polishing body relative to the gear. This embodiment... Figure 3 As shown in the figure, Figure 3 This is a side view of the grinding apparatus 6 and the polishing apparatus 17, which includes the dynamic positioning device 8. The grinding apparatus 6 and... Figure 2 The grinding device 6 is the same. However, the polishing device 17 differs in that the positioning device 8 holds the dynamically positioned and oriented rotating polishing body 81 to polish the tooth flank surface 40 of the teeth 50 of the first gear 60. The positioning device 8 is also a multi-axis robot 8, which is similar to... Figure 2 The robot 8 described in the context is the same. It is equipped with a mechanism that securely engages the polishing body 81 and rotates the polishing body at an appropriate speed. The positioning device 8 contacts the rotating polishing body 81 with a first portion of the tooth flank surface 40 to polish the first portion, and thereafter dynamically adjusts the position and orientation of the polishing body 81 relative to the first gear 60 so that a second portion of the tooth flank surface is polished by the polishing body 81.

[0090] The first gear 60 is mounted on a fixed shaft 32, so it can rotate slowly around the shaft 32 to facilitate the polishing of all its teeth 50. While the polishing device 17 polishes the teeth 50 of the first gear 60 that have been previously ground on the grinding device 6, the grinding device 6 simultaneously grinds the second gear 61.

Claims

1. A method for grinding and polishing the tooth flank surface (40) of the teeth (50) of a first gear (60), the method comprising the following steps in sequence: a) Provides a rotating grinding device (6) for grinding a first portion and a second portion of the tooth flank surface (40) of the teeth (50) of the first gear (60); A polishing apparatus (7) is provided, the polishing apparatus including a fixed shaft (31) and a polishing body (80) rotatable about the fixed shaft, the polishing body being adapted to polish the tooth flank surfaces of the gear teeth; as well as A dynamic positioning device (8) is provided for holding the first gear (60) and for dynamically adjusting the position and orientation of the first gear (60) relative to the fixed shaft (31) during polishing; as well as Provide the first gear (60); b) The grinding device (6) grinds the first and second portions of the tooth flank surface (40) of the teeth (50) of the first gear (60); c) The dynamic positioning device removes the first gear (60) from the grinding device (6); d) The dynamic positioning device (8) contacts the first portion of the tooth side surface with the rotating polishing body (80), so that the first portion of the tooth side surface is polished by the polishing body; e) The dynamic positioning device (8) dynamically adjusts the position and orientation of the first gear (60) relative to the fixed shaft (31) so that the second part of the tooth side surface is polished by the polishing body.

2. The method according to claim 1, wherein the polishing device (7) is a benchtop grinder.

3. The method according to any one of the preceding claims, wherein the second portion of the tooth flank surface (40) is polished by the rotating polishing body (80) while the grinding device (6) grinds a portion of the second gear (61).

4. The method according to any one of claims 1 to 2, wherein the second portion of the tooth flank surface (40) is polished by the rotating polishing body (80), while the rotating polishing body (80) remains in contact with the first gear (60).

5. The method according to any one of claims 1 to 2, wherein the dynamic positioning device (8) is a software-controlled robot (8) comprising a plurality of segments (90) and four, five or six axes (100), the segments being capable of rotating independently about the axes, thereby dynamically adjusting the position and orientation of the first gear (60) by rotating one or more of the axes (100).

6. The method of claim 5, wherein the robot (8) includes a sensor for sensing the force or contact pressure applied by the polishing body (80) to the first gear (60) and / or a sensor for sensing sound, and wherein the robot (8) dynamically adjusts its position and orientation in response to the output of the sensor.

7. The method according to any one of claims 1 to 2, wherein the dynamic positioning device (8) dynamically adjusts its position and orientation such that the second contact pressure when the second part is polished is different from the first contact pressure when the first part is polished.

8. The method according to any one of claims 1 to 2, wherein the polishing body (80) comprises a nonwoven material.

9. The method according to any one of claims 1 to 2, wherein the grinding apparatus (6) is adapted to grind the tooth flank surface (40) of the tooth (50) of the first gear (60) to a surface roughness Rz of 3.5 micrometers or greater, said surface roughness Rz being measured using the stylus method and a sensing sliding probe according to DIN EN ISO 3274, which came into effect on June 29, 2020, with a stylus radius of 5 micrometers and a apex cone angle of 60 degrees.

10. The method according to any one of claims 1 to 2, wherein the polishing apparatus (7) is adapted to polish the tooth flank surface (40) of the tooth (50) of the first gear (60) to a surface roughness Rz of 1.2 micrometers or less, the surface roughness Rz being measured using a stylus method and an inductive sliding probe according to DIN EN ISO 3274, which came into effect on June 29, 2020, with a stylus radius of 5 micrometers and a apex cone angle of 60 degrees.

11. The method according to any one of claims 1 to 2, wherein the first gear (60) is a gear used in the gearbox of a heavy vehicle or a gearbox of a wind turbine.

12. The method according to any one of claims 1 to 2, wherein the first gear (60) is a gear made of steel or iron.

13. The method according to any one of claims 1 to 2, wherein the first gear (60) has a diameter of 100 mm or greater, and / or the first gear (60) has a weight of 1000 g or greater, and / or wherein the first gear (60) has a gear width of 20 mm or greater, and / or wherein the first gear (60) is a helical gear.

14. A method for grinding and polishing the tooth flank surface (40) of the teeth (50) of a first gear (60), the method comprising the following steps in sequence: a) Provides a rotating grinding device (6) for grinding a first portion and a second portion of the tooth flank surface (40) of the teeth (50) of the first gear (60); A polishing apparatus (17) is provided, the polishing apparatus comprising a rotating polishing body (81) and a dynamic positioning device (8), the polishing body being adapted to polish the tooth flank surface (40) of the teeth (50) of the first gear (60), the dynamic positioning device being used to dynamically position the rotating polishing body (81) and to dynamically adjust the position and orientation of the rotating polishing body (81) relative to the first gear (60) during polishing; as well as Provide the first gear (60); b) The grinding device (6) grinds the first and second portions of the tooth flank surface (40) of the teeth (50) of the first gear (60); c) The dynamic positioning device removes the first gear (60) from the grinding device (6); d) The dynamic positioning device (8) contacts the rotating polishing body (81) with the first portion of the tooth side surface, so that the first portion of the tooth side surface is polished by the polishing body. e) The dynamic positioning device (8) dynamically adjusts the position and orientation of the rotating polishing body (81) relative to the first gear (60) so that the second part of the tooth side surface is polished by the polishing body.

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