SE545453C2 - Method and control arrangement for quality assurance when mounting bearings - Google Patents

Abstract

Method (500)/ system (300) for quality approving assembly (100) of torque transmitting ma- chine element (110), supported by bearings (120, 130) in support structure (140). The method (500) comprises: mounting (503) bearings (120, 130) in support structure (140); de- termining (504) turning torque of bearings (120, 130) when applying maximum/ minimum axial force, setting upper torque limit (UTL) and lower torque limit (LTL); mounting (506) shims and bearings (120, 130) onto torque transmitting machine element (110); determining (507) press force required to mount (506) bearings (120, 130); calculating (508) lower/ upper axial force |imits (LAFL/ UAFL); determining (509) turning torque of torque transmitting ma- chine element (110) and bearings (120, 130) as a function of axial force; determining (510) switch point (430) wherein first linear increase rate (410) of the determined (509) turning torque switches into second linear increase rate (420); and approving (51 1 a) or disapproving (511b) the assembly (100) based on measurements.

Description

METHOD AND CONTROL ARRANGEMENT FOR QUALITY ASSURANCE WHEN MOUNTING BEARINGS TECHNICAL FIELD This document discloses a method and a system. More particularly, a method and a system are described, for manufacturing and quality approving an assembly comprising a torque transmitting machine element, supported by a set of bearings in a support structure.

BACKGROUND Bearings have individual friction properties. Among other things, it is related to the tempera- ture (which in turn is depending on the time of the year) when the bearings are manufactured, or rather when the bearings are lubricated. Differences in dimensions/ tolerances of the bear- ings and components comprised therein, and/ or differences in alloy composition of the steel in different batches, fluctuations in temperature during hardening of the steel etc., may con- tribute to individualisation of friction properties of each bearing.

Therefore, manual intervention is required to establish individual parameters for turning torque when mounting bearings on a support structure, for example in a vehicle or machin- ery. The same applied pre-tension force would cause different rol|ing resistance. lt is desired however, to achieve a minimized rol|ing resistance (or a rol|ing resistance lower than a threshold limit).

Due to variations in dimensions and tolerances during production of various involved parts of the machinery, shims of different sizes are often introduced on an axis when mounting the bearing/s. lt is desired to find a way to select shims of correct dimension directly, the first time the bearings are mounted on the axis as it is time consuming and thus expensive to disassemble the bearings from the axis and change the shims. lt is desirable to find a solution to enable mounting of an axis comprising a pinion or a gear wheel, supported by bearings wherein a rol|ing resistance of the gear wheel/ pinion in a structure is approximately equally low (i.e. within a threshold limit) for all mounted structures of a production site.

SUMMARY lt would be advantageous to achieve a solution overcoming, or at least alleviating, at least one of the above-mentioned disadvantages. lt would be desirable to improve assembling of bearings supporting a rotating axis in order to achieve a consistent pre-load force and individual turning torque in production of a torque transmitting machine element mounted on the axis. To better address one or more of these concerns, a control arrangement/ method having the features defined in the independent c|aim(s) is provided.

According to a first aspect of the invention, this objective is achieved by a method for manu- facturing and quality approving an assembly of a torque transmitting machine element, sup- ported by a set of bearings in a support structure. The method comprises the steps of mount- ing the set of bearings in the support structure without mounting the torque transmitting ma- chine element. Also, the method comprises determining turning torque of the set of bearings without being mounted onto an axis of the torque transmitting machine element, as a function of a defined applied axial force, by applying a defined maximum and minimum, respectively, axial force of the assembly.

The method additionally comprises setting an upper torque limit to the determined turning torque when the defined maximum axial force is applied and a lower torque limit to the de- termined turning torque when the defined minimum axial force is applied. Then, a shims and the set of bearings are mounted onto an axis of the torque transmitting machine element in the support structure. Furthermore, the method also comprises determining a press force required to mount the set of bearings onto an axis of the torque transmitting machine ele- ment.

Additionally, the method also comprises calculating a lower axial force limit and an upper axial force limit, based on the measured press force in addition to a minimum/ maximum predefined axial force value of the set of bearings, respectively. The method comprises de- termining turning torque of the torque transmitting machine element and the set of bearings when being mounted onto the torque transmitting machine element, as a function of applied axial force, by iteratively, for all axial forces comprised in a set of distinct axial forces: apply- ing one axial force at the time, of the set of axial forces onto the set of bearings; measuring a turning torque value of the torque transmitting machine element and the set of bearings at the applied axial force; and associating the measured turning torque value with the applied axial force.

The method furthermore comprises determining a switch point wherein a first approximately linear increase rate of the determined turning torque as a function of the applied axial force switches into a second approximately linear increase rate.

The method also comprises approving, or disapproving, the assembly when the turning torque at the switch point is higher than the set lower torque limit and is lower than the set upper torque limit, while the applied axial force at the switch point is higher than the calcu- lated lower axial force limit and is lower than the calculated upper axial force limit.

According to a second aspect of the invention, this objective is achieved by a system. The system aims at manufacturing and quality approving an assembly of a torque transmitting machine element, supported by a set of bearings in a support structure. The system com- prises a first press station, a second press station and a control arrangement, which is com- municatively connected to the first press station and the second press station. ln some embodiments, a third press station may be additionally comprised, configured to estimate press force to X-axis of Quality Approval. The third press station may be communi- catively connected to the control arrangement.

The first press station is configured to mount the set of bearings in the support structure without mounting the torque transmitting machine element, apply a defined maximum and minimum, respectively, axial force of the assembly, measure a resulting turning torque of the set of bearings and provide the respective measurement values to the control arrangement.

The second press station is configured to mount a shims and the set of bearings onto an axis of the torque transmitting machine element in the support structure by applying an axial press force, measure turning torque as a function of applied axial forces and provide the respective measurement values to the control arrangement.

The control arrangement is configured to obtain measurement values from the respective press station. Based on these obtained measurements, the control arrangement is config- ured to set an upper torque limit to the turning torque when the defined maximum axial force is applied, and a lower torque limit to the determined turning torque when the defined mini- mum axial force is applied, as obtained from the first press station. Additionally, the control arrangement is configured to calculate a lower axial force limit and an upper axial force limit, based on the press force in addition to a minimum/ maximum predefined axial force value of the set of bearings, respectively, as obtained from the second press station. ln addition, the control arrangement is further configured to determine a switch point wherein an approximately first linear change rate of the turning torque as a function of the applied axial force switches into a second approximately linear lower change rate, as obtained from the second press station. The control arrangement is also configured to, based on the deter- mined switch point, approve the assembly when the turning torque at the switch point is higher than the set lower torque limit and is lower than the set upper torque limit, while the applied axial force at the switch point is higher than the calculated lower axial force limit and is lower than the calculated upper axial force limit.

Alternatively, in case approval according to the criterion cannot be made, the assembly is disapproved.

Thanks to the described aspects, by determining rolling resistance of the bearings without being mounted on the torque transmitting machine element, for an estimated axial force of the assembly when it is in operation, reference limitation values of torque limits and axial force limits are obtained. By gradually increasing axial force while measuring turning torque values, a switch point is discovered wherein compression of bearing rollers of the bearings is turning into elastic compression of the axis of the torque transmitting machine element and the shims, due to the distinct respective properties of these entities. The assembly could thereby be quality assured, when the switch point is within the reference limitation values.

By performing measurements simultaneously with mounting the assembly, a time-efficient assembly procedure is achieved as post-production quality control is not required, or could at least be limited to visual inspection.

Bearings and shims of the assembly are compressed by an axial force until reaching a state where the cannot be further compressed when the axial force is further increased. lnstead, the pinion/ torque transmitting machine element is compressed. By determining this switch point, a consistent pre load force is achieved for all bearings, leading to a streamlined pro- duction with a predictable and consistent result.

A consistent correct pre-load of the bearings is thus assured for all assemblies of the manu- factory is achieved, leading to higher quality of the final vehicle or machinery wherein the assembly is comprised.

Correctly mounted bearings, correctly selected shims and a correct pre-load will lead to lower friction of the vehicle/ machinery, but also into longer expected lifetime of the assembly and generally to an improved driving experience. Less friction also leads to noise reduction.

Other advantages and additional novel features will become apparent from the subsequent detailed description.

FIGURES Embodiments of the invention will now be described in further detail with reference to the accompanying figures, in which: Figure1 illustrates an assembly comprising a torque transmitting machine element, supported by a set of bearings in a support structure vehicle, according to an embodiment of the invention.

Figure 2 illustrates a vehicle comprising an assembly according to an embodiment of the invention.

Figure 3 schematically illustrates an assembly line according to an embodiment of the invention.

Figure 4A illustrates examples of measurements of turning torque of the torque trans- mitting machine element, as a function of provided axial pressure.

Figure 4B illustrates examples of measurements of turning torque of the torque trans- mitting machine element, as a function of provided axial pressure.

Figure 5A-5C is a flow chart illustrating an embodiment of a method.

DETAILED DESCRIPTION Embodiments of the invention described herein are defined as a method and a system, which may be put into practice in the embodiments described below. These embodiments may, however, be exemplified and realised in many different forms and are not to be limited to the examples set forth herein; rather, these illustrative examples of embodiments are provided so that this disclosure will be thorough and complete.

Still other objects and features may become apparent from the following detailed description, considered in conjunction with the accompanying drawings. lt is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the herein disclosed embodiments, for which reference is to be made to the appended claims. Further, the drawings are not necessarily drawn to scale and, unless oth- en/vise indicated, they are merely intended to conceptually illustrate the structures and pro- cedures described herein.

Figure 1 illustrates an assembly 100, comprising a torque transmitting machine element 110, supported by a set of bearings 120, 130 in a support structure The torque transmitting machine element 110 may be a pinion and the support structure 140 may be embodied as a transmission housing, wherein the axis of the pinion is supported by the set of bearings 120, ln the illustrated example, the set of bearings 120, 130 comprises two bearings. This is merely an arbitrary example; other embodiments may comprise another number of bearings 120, 130. The bearings 120, 130 may be tapered roller bearings in an embodiment.

Tapered roller bearings are rolling element bearings that can support axial forces, as well as radial forces. The inner and outer raceways of the tapered roller bearings are segments of cones and the rollers are tapered so that the conical surfaces and the conical surfaces of the raceways and the roller axes, if projected, would all meet at a common point on the main axis of the bearing 120, 130. This geometry makes the motion of the cones remain coaxial, without sliding motions between the raceway and the outside diameter of the rollers.

The conical geometry creates a linear contact path which permits greater loads to be carried than spherical/ ball bearings which merely have point contact.

The bearings 120, 130 may sometimes be categorised as ultra-low friction bearings. Other bearing types may however be utilised.

The torque transmitting machine element/ pinion 110 may propel an axis via an annual wheel.

However, in other embodiments, the torque transmitting machine element 110 may comprise a gear wheel and the support structure 140 may be embodied as a gear box housing.

Figure 2 illustrates a scenario with a vehicle 200 comprising an assembly 100 for propelling a drive axle/ rear axle of the vehicle The vehicle 200 may comprise a means for transportation in broad sense such as e.g. a truck, a car, a motorcycle, a trailer, a bus, a bike, a train, an aircraft, a watercraft, a drone, a spacecraft, or other similar manned or unmanned (autonomous) means of conveyance run- ning e.g. on wheels, rails, air, water, space or similar media.

However, the assembly 100 is in particular suitable to operate on a heavy vehicle configured to handle a heavy load such as a truck, trailer, buss, etc., which may be driver controlled or driverless (i.e. autonomously controlled) in different embodiments.

The axial load of the assembly 100 may for this reason be relatively high, for example 10-30 tons during operation in a non-limiting example, which puts exceptionally high demands on the torque transmitting machine element 110 and the bearings 120, Figure 3 schematically illustrates an example of an assembly system 300 wherein the as- sembly 100 is manufactured according to the provided method.

The system 300 in the illustrated embodiment comprises a first press station 310, a second press station 320 and a control arrangement 330, which is communicatively connected to the first press station 310 and the second press station 320. The involved entities 310, 320, 330 may be separate physical entities, or comprised in the same physical entity in different embodiments. ln the first press station 310, the bearings 120, 130 are preliminary mounted in the support structure 140 without mounting the torque transmitting machine element 110. An axial force is applied at the first press station 310, which is corresponding to a defined maximum and minimum, respectively, axial force of the assembly 100, as is expected to represent a maxi- mum and minimum load of the axis/ vehicle 200 when operating. ln some non-limiting em- bodiments, the defined minimum axial load may be set to a kN and the defined maximum axial load may be set to a + b kN, where a and b are arbitrary positive integers.

During the application of the maximum/ minimum axial forces, the respective resulting turning torque are measured at the first press station 310, and provided to the control arrangement 330, where they later are used.

The bearings 120, 130 are then removed from the support structure 140 and the elements of the assembly 100 are fon/varded to the second press station l\/leasurements of dimensions of the torque transmitting machine element 110, the bearings 120, 130 and/ or the support structure 140 may be performed and based there upon, shims of an appropriate dimension may be selected, to be applied onto the torque transmitting machine element Accurate adjustment and positioning of the machine elements comprised in the assembly 100 in relation to each other is an essential element of an alignment process. Shims may typically be made of high quality stainless steel in close tolerances for accurate alignment. Other metallic alloys may alternatively be applied in some embodiments. Even small dimen- sion/ tolerance deviations in the torque transmitting machine element 110, the bearings 120, 130 and/ or the support structure 140 may lead to severe impairment in the final product when the torque transmitting machine element 110 is rotating. Shims of appropriate dimen- sions assure that the axial distance between the involved elements is appropriate, within a tolerance.

At the second press station 320, the selected shims and the set of bearings 120, 130 are mounted onto an axis of the torque transmitting machine element 1 10 in the support structure 140. Meanwhile, an incremental axial force is applied. An axial force of for example 10 kN may initially be applied. The axial force may then be incremented by 5 kN or some other convenient, relatively small step size, thereby gradually increasing the press fit of the bear- ings 120, 130 against the axis of the torque transmitting machine element 110 in the support structure 140. The respective inner segments of the bearings 120, 130 will then slide axially along the axis of the torque transmitting machine element 110 until reaching their respective seating. Pre-tension is then established within the bearings 120, The press force required to mount the bearings 120, 130 onto the axis of the torque trans- mitting machine element 110 is estimated and provided to the control arrangement Meanwhile, the torque transmitting machine element 110 may be rotating according to a predefined rotational speed and a measurement of the resulting turning torque is made. These measurements are also provided to the control arrangement The control arrangement 330, based on the obtained measurements at the first press station 310 and the second press station 320, respectively, may then determine a switch point 430 wherein an approximately first linear increase rate 410 of the determined turning torque as a function of the applied axial force switches into a second approximately linear increase rate 420, as illustrated in Figure 4A and Figure 4B.

The first linear increase rate 410 of the turning torque as a function of the applied axial force may be caused by compression of bearing rollers of the bearings 120, 130, while the second linear increase rate 420 of the turning torque as a function of the applied axial force may be caused by compression of the torque transmitting machine element 110 and/ or the shims. By gradually increasing axial force while measuring the turning torque values, the switch point 430 is discovered wherein compression of bearing rollers of the bearings 120, 130, substantially following the first linear increase rate 410, is turning into compression of the axis of the torque transmitting machine element 110 and the shims, which substantially is following the second approximately linear increase rate 420, due to the distinct respective properties of these entities. ln case the turning torque at the switch point 430 is higher than the lower torque limit LTL yet being lower than the upper torque limit UTL, while the applied axial force at the switch point 430 is higher than the lower axial force limit LAFL yet being lower than the upper axial force limit UAFL, the assembly 100 is approved. This is illustrated in Figure 4A.

Othen/vise, when the switch point 430 is outside an area defined by the lower torque limit LTL, the upper torque limit UTL, the lower axial force limit LAFL and the upper axial force limit UAFL, i.e. when the turning torque at the switch point 430 is lower than the lower torque limit LTL or higher than the upper torque limit UTL, and/ or the applied axial force at the switch point 430 is lower than the lower axial force limit LAFL, or higher than the upper axial force limit UAFL, the assembly 100 is disapproved.

An example of the latter scenario is depicted in Figure 4B, wherein the turning torque at the switch point 430 is lower than the lower torque limit LTL, with a difference A.

The pre-load applied to the bearings 120, 130 is maintained by a nut or similar machine element by a torque wrench or corresponding arrangement for determining the pre-load. The pre-load may correspond to the axial force of the determined switch point 430, when the assembly 100 has been approved. ln some embodiments, an attempt may be made, when the assembly 100 has been disap- proved, to get the assembly 100 into the approved state without replacing shims, by adjusting the determined pre-load to be applied to the set of bearings 120, 130 when mounted into the assembly 100, e.g. by adjusting angular position of the nut/ similar machine element.

The size of the adjusted pre-load may be proportional to the difference A between the turning torque at the determined switch point 430 and the lower torque limit LTL when the turning torque is lower than the lower torque limit LTL. That is, the pre-load may be increased by rotating the nut clockwise by a rotational distance proportional with the difference A. ln some embodiments, the difference A between the turning torque at the determined switch point 430 and the lower torque limit LTL and/ or upper torque limit UTL, may be compared with a predetermined or configurable turning torque threshold limit, for example maximum 5- 10% of the turning torque at the determined switch point 430 (non-limiting example). The adjustment of the determined pre-load to be applied to the set of bearings 120, 130 when mounted into the assembly 100 may be performed when the difference A is smaller than the turning torque threshold limit. When the difference A exceeds the turning torque threshold limit, it may be considered better to instead directly dismount the assembly 100 and replace the shims for another one with a different dimension.

Figures 5A-5C illustrate an example of a method 500 for manufacturing and quality approv- ing an assembly 100 of a torque transmitting machine element 110, supported by a set of bearings 120, 130 in a support structure The assembly 100 of the torque transmitting machine element 110, supported by the set of bearings 120, 130 in the support structure 140 may be comprised in a vehicle The vehicle 100 may be any arbitrary kind of means for conveyance, such as a truck, a bus Ol' a Caf, STC. ln order to correctly be able to perform the manufacturing and quality approval of the assem- bly 100, the method 500 may comprise a number of steps 501-514. However, some of these steps 501-514 may be performed solely in some alternative embodiments, like e.g. steps 501-502 and/ or steps 512-514. Further, the described steps 501-514 may be performed in a somewhat different chronological order than the numbering suggests. The method 500 may comprise the subsequent steps: Step 501 which only may be performed in some embodiments, comprises measuring a di- mension of the torque transmitting machine element 110, the set of bearings 120, 130 and/ or the support structure The torque transmitting machine element 110 may be embodied as a pinion. The set of bearings 120, 130 may comprise two bearings 120, 130 in some embodiments; or alterna- tively one, three, four, etc., bearings 120, 130 in different embodiments. The support struc- ture 140 may comprise a transmission housing or a gear box housing in different embodi- mentS.

Step 502 which only may be performed in some embodiments wherein step 501 has been performed, comprise selecting dimension of a shims to be applied onto the torque transmit- ting machine element 110, based on the measurement The selection may be based on measurements of the torque transmitting machine element 110, the bearings 120, 130, the support structure 140 and various respective segments thereof, and a comparison with predefined measurement value.

Step 503 comprises mounting the set of bearings 120, 130 in the support structure 140 with- out mounting the torque transmitting machine elementThe mounting 503 may be made in a first press station 310 of an assembly system 300 in some embodiments.

Step 504 comprises determining turning torque of the set of bearings 120, 130 without being mounted onto an axis of the torque transmitting machine element 110, as a function of an applied axial force, by applying a defined maximum and minimum, respectively, axial force of the assembly The defined maximum axial force may be representative of an expected maximum axial force during normal operation, for example representing load of a rear axle of a vehicle 200 fully loaded with cargo. The defined minimum axial force may be representative of an expected minimum axial force during normal operation; for example representing load of a rear axle of an unloaded vehicle Step 505 comprises setting an upper torque limit UTL to the determined 504 turning torque when the defined maximum axial force is applied, and a lower torque limit LTL to the deter- mined 504 turning torque when the defined minimum axial force is applied.

Step 506 comprises mounting a shims and the set of bearings 120, 130 onto an axis of the torque transmitting machine element 110 in the support structure Step 507 comprises determining a press force required to mount 506 the set of bearings 120, 130 onto an axis of the torque transmitting machine element Step 508 comprises calculating a lower axial force limit LAFL and an upper axial force limit UAFL, based on the determined 507 press force in addition to a minimum/ maximum prede- fined axial force value of the set of bearings 120, 130, respectively.

Step 509 comprises determining turning torque of the torque transmitting machine element 110 and the set of bearings 120, 130 when being mounted onto the torque transmitting ma- chine element 110, as a function of applied axial force.

The turning torque is determined by iteratively, for all axial forces comprised in a set of dis- tinct axial forces: applying one axial force at the time, of the set of axial forces onto the set of bearings 120, 130; measuring a turning torque value of the torque transmitting machine element 110 and the set of bearings 120, 130 at the applied axial force; associating the measured turning torque value with the applied axial force.The axial force may be applied to the front bearing inner cone while counter holding the torque transmitting machine element 110/ pinion, and create a data set with a significant knee shape function, which can be used to calculate the actual pre-load of the bearing set 120, Step 510 comprises determining a switch point 430 wherein an approximately first linear increase rate 410 of the determined 509 turning torque as a function of the applied axial force switches into a second approximately linear increase rate The first linear increase rate 410 of the determined 509 turning torque as a function of the applied axial force may substantially be caused by compression of bearing rollers of the bearings 120, 130 in some embodiments, while the second linear increase rate 420 of the determined 509 turning torque as a function of the applied axial force may be substantially caused by compression of the torque transmitting machine element This may be done by linear regression to two parts of the data set. A first function describes the bearing rollers compression, and second part describes the pinion shaft/ torque trans- mitting machine element 110 compression.

When the Y1 = kX+m and Y2 = kX+m is calculated, the intersection of those are found. When the intersection coordinates are found the second parameter (the axial press force) may be subtracted by the X-Coordinate. Based on the made calculations, the pre load may be determined.

Steps 511a and 511 b may be alternatively performed.

Step 511a comprises approving the assembly 100 when the turning torque at the switch point 430 is higher than the set 505 lower torque limit LTL and is lower than the set 505 upper torque limit UTL, while the applied axial force at the switch point 430 is higher than the cal- culated 508 lower axial force limit LAFL and is lower than the calculated 508 upper axial force limit UAFL. ln case step 511a cannot be performed, step 511b may be performed instead. Step 511b comprises disapproving the assembly 100 comprising the shims, the set of bearings 120, 130 and the torque transmitting machine element 110 in the support structure Step 512, which only may be performed in some embodiments, comprises determining a pre-load to be applied to the set of bearings 120, 130 when mounted into the assemblyThe pre-load may correspond to the axial force of the determined 510 switch point 430, when the assembly 100 has been approved 511a.

The pre-load is established and maintained by turning a nut onto the support structure 140, thereby holding and maintaining the pre-load of the torque transmitting machine element 110, the shims and the set of bearings 120, Step 513, which only may be performed in some embodiments wherein the assembly 100 has been disapproved 511b, comprises comparing the difference A between the turning torque at the determined 510 switch point 430 and the lower torque limit LTL and/ or upper torque limit UTL, respectively, with a turning torque threshold limit.

Step 514, which only may be performed in some embodiments wherein the assembly 100 has been disapproved 511b and step 512 has been performed, comprises adjusting the de- termined 512 pre-load to be applied to the set of bearings 120, 130 when mounted into the assembly 100, and repeating method steps 509-511 of the method 500, in order to enable approval 511a of the assembly 100. The size of the adjusted pre-load may be proportional to a difference A between the turning torque at the determined 510 switch point 430 and the lower torque limit LTL when the turning torque is lower than the lower torque limit LTL. Also, or alternatively, the size of the adjusted pre-load may be proportional to a difference A be- tvveen the turning torque at the determined 510 switch point 430 and the upper torque limit UTL when the turning torque is higher than the upper torque limit UTL. ln some embodiments wherein method step 513 has been performed, the step of adjusting 514 the determined 512 pre-load to be applied to the set of bearings 120, 130 when mounted into the assembly 100 may be performed only when the difference A between the turning torque at the determined 510 switch point 430 and the lower torque limit LTL and/ or upper torque limit UTL is smaller than the turning torque threshold limit.

Thereby, in case the difference A between the turning torque at the determined 510 switch point 430 and the lower torque limit LTL and/ or upper torque limit UTL exceeds the turning torque threshold limit, it may not be considered possible to adjust the pre-load sufficiently to enable approval of the assembly 100, why it may be better to immediately proceed to ex- change of shims.

The system 300 comprises a control arrangement 330 for manufacturing and quality approv- ing an assembly 100 of a torque transmitting machine element 110, supported by a set of bearings 120, 130 in a support structure 140. The control arrangement 330 iscommunicatively connected to a first press station 310 and a second press station 320. The first press station 310 may be distinct from, or identical/ collocated with, the second press station 320 in different embodiments.

The control arrangement 330 is configured to perform at least some of the method steps 501-514, according to the previously described method 500, based on measurement values obtained from the first press station 310 and/ or the second press station ln particular, the control arrangement 330 may be configured to set an upper torque limit UTL to the turning torque when the defined maximum axial force is applied, and a lower torque limit LTL to the determined turning torque when the defined minimum axial force is applied, as obtained from the first press station The control arrangement 330 may comprise a receiving circuit configured for receiving wire- less and/ or wired signals from the first press station 310 and/ or the second press station The control arrangement 330 may also comprise a processing circuitry configured for per- forming at least some of the calculating and/ or computing operations of the control arrange- ment 330. Thus, the processing circuitry may be configured for operation control and quality approving of the assembly 100 by performing and/ or supervising at least some of the steps 501-514 of the method Such processing circuitry may comprise one or more instances of a processing circuit, i.e. a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), or other processing logic that may interpret and execute instructions. The herein utilised expression "processing circuitry" may thus represent a processing device comprising a plurality of pro- cessing circuits, such as, e.g., any, some or all of the ones enumerated above.

Furthermore, the control arrangement 330 may comprise or be connected to a memory or database in some embodiments. The optional memory may comprise a physical device uti- lised to store data or programs, i.e., sequences of instructions, on a temporary or permanent basis. According to some embodiments, the memory may comprise integrated circuits com- prising silicon-based transistors. The memory may comprise e.g. a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile or non-volatile storage unit for storing data such as e.g. ROIVI (Read-Only l\/lemory), PROIVI (Programmable Read-Only Memory), EPROIVI (Erasable PROIVI), EEPROIVI (Electrically Erasable PROIVI), etc. in differ- ent embodiments.

Further, the control arrangement 330 may comprise a signal transmitter. The signal trans- mitter may be configured for transmitting a control signal over a wired or wireless interface to the first press station 310 and/ or the second press stationAt least some of the previously described steps 501 -51 4 to be performed in or be supervised by the control arrangement 330 may be implemented through the one or more processing circuitries within the control arrangement 330, together with computer program product for performing at least some of the functions of the method steps 501-514. Thus, a computer program product, comprising instructions for performing at least some of the method steps 501-514 may perform the method when executed by a computer.

The computer program product mentioned above may be provided for instance in the form of a data carrier carrying computer program code for performing at least some of the method steps 501-514 according to some embodiments when being loaded into the one or more processing circuitries of the control arrangement 330. The data carrier may be, e.g., a memory device that may hold machine readable data in a non-transitory manner. The com- puter program product may furthermore be provided as computer program code on a server and downloaded to the control arrangement 330 remotely, e.g., over an Internet or an intra- net connection.

Further, some embodiments may comprise a vehicle 200 comprising the assembly 100 of the torque transmitting machine element 110, supported by the set of bearings 120, 130 in the support structure 140, wherein the assembly 100 has been manufactured and quality approved according to the method 500 according to at least some of the method steps 501- The terminology used in the description of the embodiments as illustrated in the accompa- nying drawings is not intended to be limiting of the described method 500; system 300; con- trol arrangement 330; computer program; computer program product or vehicle 200. Various changes, substitutions or alterations may be made, without departing from invention embod- iments as defined by the appended claims.

As used herein, the term "and/ or" comprises any and all combinations of one or more of the associated listed items. The term "or" as used herein, is to be interpreted as a mathematical OR, i.e., as an inclusive disjunction; not as a mathematical exclusive OR (XOR), unless ex- pressly stated othen/vise. ln addition, the singular forms "a", "an" and "the" are to be inter- preted as "at least one", thus also possibly comprising a plurality of entities of the same kind,unless expressly stated otherwise. It will be further understood that the terms "inc|udes", "comprises", "including" or "comprising", specifies the presence of stated features, actions, integers, steps, operations, elements, or components, but do not preclude the presence or addition of one or more other features, actions, integers, steps, operations, elements, com- ponents, or groups thereof. A single unit such as e.g. a processor may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutu- ally different dependent claims does not indicate that a combination of these measures can- not be used to advantage. A computer program may be stored/ distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware but may also be distributed in other forms such as via Internet or other wired or wireless communication system.

Claims (9)

Claims

1. A method (500) for manufacturing and quality approving an assembly (100) of a torque transmitting machine element (110), supported by a set of bearings (120, 130) in a support structure (140); wherein the method (500) comprises the steps of: mounting (503) the set of bearings (120, 130) in the support structure (140) without mounting the torque transmitting machine element (110); determining (504) turning torque of the set of bearings (120, 130) without being mounted onto an axis of the torque transmitting machine element (110), as a function of an applied axial force, by applying a defined maximum and minimum, respectively, axial force of the assembly (100); setting (505) an upper torque limit (UTL) to the determined (504) turning torque when the defined maximum axial force is applied, and a lower torque limit (LTL) to the de- termined (504) turning torque when the defined minimum axial force is applied; mounting (506) a shims and the set of bearings (120, 130) onto an axis of the torque transmitting machine element (110) in the support structure (140); determining (507) a press force required to mount (506) the set of bearings (120, 130) onto an axis of the torque transmitting machine element (110); calculating (508) a lower axial force limit (LAFL) and an upper axial force limit (UAFL), based on the determined (507) press force in addition to a minimum/ maximum predefined axial force value of the set of bearings (120, 130), respectively; determining (509) turning torque of the torque transmitting machine element (110) and the set of bearings (120, 130) when being mounted onto the torque transmitting machine element (1 10), as a function of applied axial force, by iteratively, for all axial forces comprised in a set of distinct axial forces: applying one axial force at the time, of the set of axial forces onto the set of bearings (120, 130); measuring a turning torque value of the torque transmitting machine element (110) and the set of bearings (120, 130) at the applied axial force; associating the measured turning torque value with the applied axial force; determining (510) a switch point (430) wherein a first approximately linear increase rate (410) of the determined (509) turning torque as a function of the applied axial force switches into a second approximately linear increase rate (420); and approving (511a) the assembly (100) when the turning torque at the switch point (430) is higher than the set (505) lower torque limit (LTL) and is lower than the set (505) upper torque limit (UTL), while the applied axial force at the switch point (430) is higher than the calculated (508) lower axial force limit (LAFL) and is lower than the calculated (508) upper axial force limit (UAFL); or otherwise, disapproving (511b) the assembly of the shims, the set of bearings (120, 130) and the torque transmitting machine element (110) in the support structure (140).

2. The method (500) according to claim 1, further comprising the steps of: measuring (501) a dimension of the torque transmitting machine element (110), the bearing (120, 130) and/ or the support structure (140); and selecting (502) dimension of a shims to be applied onto the torque transmitting ma- chine element (110), based on the measurement (501 ).

3. The method (500) according to any one of claim 1 or claim 2, further comprising the step of: determining (512) a pre-load to be applied to the set of bearings (120, 130) when mounted into the assembly (100), which pre-load corresponds to the axial force of the deter- mined (510) switch point (430), when the assembly (100) has been approved (51 1 a).

4. The method (500) according to claim 3, to be performed when the assembly (100) has been disapproved (51 1 b), further comprising the step of: adjusting (514) the determined (512) pre-load to be applied to the set of bearings (120, 130) when mounted into the assembly (100), and repeating method steps 509-511 in order to enable approval (51 1 a) of the assembly (100); wherein the size of the adjusted (514) pre-load is proportional to a difference (A) between the turning torque at the determined (510) switch point (430) and the lower torque limit (LTL) when the turning torque is lower than the lower torque limit (LTL); or a difference (A) between the turning torque at the deter- mined (510) switch point (430) and the upper torque limit (UTL) when the turning torque is higher than the upper torque limit (UTL).

5. The method (500) according to any one of claims 3-4, for an assembly (100) which has been disapproved (51 1 b), further comprising the step of: comparing (513) the difference (A) between the turning torque at the determined (510) switch point (430) and the lower torque limit (LTL) and/ or upper torque limit (UTL), respectively, with a turning torque threshold limit; and performing the step of adjusting (514) the determined (512) pre-load to be applied to the set of bearings (120, 130) when mounted into the assembly (100) when the difference (A) between the turning torque at the determined (510) switch point (430) and the lower torque limit (LTL) and/ or upper torque limit (UTL) is smaller than the turning torque threshold limit.

6. The method (500) according to any one of claims 1-5, wherein the first linear in- crease rate (410) of the determined (509) turning torque as a function of the applied axial force is substantially caused by compression of bearing rollers of the bearings (120, 130), while the second linear increase rate (420) of the determined (509) turning torque as a func- tion of the applied axial force is substantialiy caused by compression of the torque transmit- ting machine element (1 1 O).

7. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out at least some of the steps of the method (500) according to any one of claims 1-

8. A computer-readabie storage medium comprising instructions which, when exe- cuted by a computer, cause the computer to carry out at least some of the steps of the method (500) according to any one of claims 1-

9. A system (300) for manufacturing and quality approving an assembly (100) of a torque transmitting machine element (110), supported by a set of bearings (120, 130) in a support structure (140); wherein the system (300) comprises a first press station (310), configured to mount the set of bearings (120, 130) in the support structure (140) without mounting the torque transmitting machine element (110), ap- ply a defined maximum and minimum, respectively, axial force of the assembly (100), meas- ure a resulting turning torque of the set of bearings (120, 130) and provide the respective measurement values to a control arrangement (330); a second press station (320), configured to mount a shims and the set of bearings (120, 130) onto an axis of the torque transmitting machine element (110) in the support structure (140) by applying an axial press force, measure turning torque as a function of applied axial forces and provide the respective measurement values to the control arrange- ment (330); and the control arrangement (330) communicatively connected to the first press station (310) and the second press station (320), wherein the control arrangement (330) is config- ured to obtain measurement values from the respective press station (310, 320); set an upper torque limit (UTL) to the turning torque when the defined maxi- mum axial force is applied, and a lower torque limit (LTL) to the determined turning torque when the defined minimum axial force is applied, as obtained from the first press station (310); calculate a lower axial force limit (LAFL) and an upper axial force limit (UAFL), based on the press force in addition to a minimum/ maximum predefined axial force value of the set of bearings (120, 130), respectively, as obtained from the second press station (320); determine a switch point (430) wherein a first approximately linear increase rate (410) of the turning torque as a function of the applied axial force switches into a second approximately linear increase rate (420), as obtained from the second press station (320); and approve the assembly (100) when the turning torque at the switch point (430) is higher than the set lower torque limit (LTL) and is lower than the set upper torque limit (UTL), while the applied axial force at the switch point (430) is higher than the calculated lower axial force limit (LAFL) and is lower than the calculated upper axial force limit (UAFL); or otherwise, disapprove the assembly of the set of bearings (120, 130) and the torque transmitting machine element (110) in the support structure (140).