GB2521390A

GB2521390A - Rolling element and bearing

Info

Publication number: GB2521390A
Application number: GB1322412.6A
Authority: GB
Inventors: Alejandro Sanz
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 2013-12-18
Filing date: 2013-12-18
Publication date: 2015-06-24
Also published as: GB201322412D0; WO2015091728A1

Abstract

A rolling element 100 for a bearing is at least partially constituted of a first printed material 105 being printed via an additive manufacturing process, such as direct laser deposition or stereo-lithography, selective laser sintering, selective laser melting, laminated object manufacturing, fused deposition modelling, selective binging, laser engineering net shaping, photo polymerization, selective electron beam sintering. The first printed material 105 comprises at least one channel 110, 120 open to an outer surface of the rolling element, the channel being configured and constructed to transport, in use, lubricant. The rolling element may comprise a hollow structure 130 containing a lubricant sponge 135 for supplying the outer surface of the rolling element with lubricant, in use. The rolling element may comprise a sensor (264, fig 2) and a controller (262, fig 2) for activating release of the lubricant.

Description

ROLLING ELEMENT AND BEARING

FIELD OF THE INVENTION

The invention relates to rolling element for a bearing. The invention further relates to a bearing element.

BACKGROUND ART

Additive manufacturing or more commonly called 3D printing is a known production technique in which a three-dmensional solid object is generated from a digital model. The process of additive manufacturing starts with generating the digital model via any known digital modeling methods, such as using a CAD program. Next, the digital model is divided into slices in which each slice indicates for this layer of the digital model where the printed material should be located. The individual slices are sequentially fed into an additive manufacturing tool or 3D printer which deposits the material according to the individual slices and as such generates the complete three-dimensional solid object layer by layer.

In the early days of additive manufacturing, mainly plastic materials or resins have been used as printed material for generating the three-dimensional solid object, but other processes have been developed in which also other materials, including different types of metal may be deposited in layers using this additive manufacturing technique. A major benefit of this manufacturing technique is that it allows the designer to produce virtually any three-dimensional object in a relatively simple production method. This may be especially beneficial when, for example, an initial model is required of a product or when only a limited number of products are required. A drawback of this manufacturing technique is the speed at which the three-dimensional solid objection is produced.

The use of additive manufacturing in high-quality bearings has been limited.

This is caused by material requirements for such high-quality bearings which seem insufficient for the current materials applied via the additive manufacturing process.

SUMMARY OF THE INVENTION

One of the objects of the invention is to provide a rolling element for a bearing in which the rolling element comprises printed material printed via additive manufacturing.

A first aspect of the invention provides a rolling element for a bearing according to claim 1. A second aspect of the invention provides the bearing according to claim 15. Embodiments are defined in the dependent claims.

The rolling element in accordance with the first aspect of the invention being at least partially constituted of a first printed material being printed via an additive manufacturing process, the first printed material comprising at least one channel open to an outer surface of the rolling element, the channel being configured and constructed to transport, in use, lubricant.

The inventors have realized that rolling elements may at least partially be generated using first printed material being material applied via the additive manufacturing process. This use of printed material provides many additional design freedoms in designing rolling elements for bearings. In the current invention, the inventors have realized that lubricant inside a bearing migrates and that the use of the rolling element which at least partially comprises first printed material may be used to control this migration of lubricant inside the bearing. The migration of lubricants may cause a surplus of lubricants at locations where the lubricants are not needed or preferably not present during use. In such a situation, the presence of the lubricant would increase the wear at that location and thus would reduce the smooth operation of the bearing. Alternatively, a shortage of lubricants at locations where the lubricants are required may occur due to the migration of lubricants which may reduce the smooth operation of the bearing. In either case, the operation of the bearing is not optimal. The inventors have realized that the use of a channel having an opening to the outer surface of the rolling element may be generated using the first printed material. Such a channel may be used to extract lubricant at a location where the lubricant is not required during operation, for example, choosing the dimensions of the channel to achieve a capillary effect to absorb lubricant. Alternatively, the channel may be designed to contain lubricant and deposit the lubricant, in use, at locations where the lubricant is required. As such, the use of the rolling element comprising the first printed material having a channel to the outer surface of the rolling element enables to control the migration of the lubricant inside the bearing to ensure that the lubricant is at the right location and in sufficient quantity to ensure smooth operation of the bearing.

A bearing typically has a plurality of rolling elements inside the bearing to ensure a smooth operation of the bearing. All of the rolling elements inside the bearing may comprise a rolling element having the first printed material according to the current inventon, or only one or two rolling elements may have the first printed material according to the current invention.

In an embodiment of the rolling element, the at least one channel is an extraction channel configured for drawing lubricant into the at least one channel from outside the rolling element. The extraction channel may use, for example, a capillary force to extract the lubricant from outside the rolling element into the at least one channel. As already briefly indicated above, the dimensions of the at least one channel may be designed such that the channel may absorb part of the lubricant into the channel via the capillary force. The extraction may be enhanced by pressure difference that may result from the lubricant to be dispersed from another channel out of the rolling element. Also thermal difference may contribute to the extraction of the lubricant from outside the rolling element as an inside of the roller may have a higher temperature compared to the outer surface of the rolling element which is configured to contact, in use, the raceway contacting surface.

In an embodiment of the rolling element, the extraction channel is open to the outer surface of the rolling element through an extraction opening for drawing the lubricant, the extraction opening being located at a part of the outer surface of the rolling element where no lubricant is required in operation. In a bearing, lubricant is only required at a contact area between moving parts -in this case between the rolling element and the raceway of the inner ring or outer ring of the bearing. Of course, lubricant may also be present between a case or seal and the rolling element.

However, at some locations inside the bearing, for example, at the edge of the contact area between the raceway and the rolling element, very little or preferably no lubricant should be present, because lubricant at this location only increases the wear between the rolling elements and the raceway surface and may further prevent the smooth rolling of the rolling elements inside the bearing. Having the extraction channel located at the outer surface of the rolling element where the rolling element moves along the edge of the raceway surface, the extraction channel may extract the access of lubricant and thus ensure a smooth rotation of the rolling elements, in use.

In an embodiment of the rolling element, the at least one channel is a supply channel configured for supplying lubricant to the outer surface of the rolling element for, in use, lubricating rolling elements in the bearing. As also already indicated above, the at least one channel may also be used to deposit lubricant at a position where lubricant is needed to ensure a smooth operation of the rolling element inside the bearing. Using the first printed material enable to generate the at least one channel which has an opening to the outer surface of the rolling element. This channel may supply the lubricant to the outer wall of the rolling element. Using this at least one channel able to deposit the lubricant exactly at the location where it is needed, further ensures that only minimal lubricant may be inserted into the bearing to ensure the smooth operation. In known bearings, surplus of lubricant may be added to ensure that at least enough lubricant is present where the lubricant really is required for the smooth operation. Next to environmental drawbacks, this access of lubricant may also lead to the accumulation of the lubricant at locations where they are not preferred and even reduce the efficiency or damage the bearing. Using the rolling element which is at least partially constituted of the first printed material comprising the at least one channel may deposit the lubricant only at the location where really necessary, minimizing the amount of lubricants necessary.

The use of the supply channel for supplying lubricants to the outer surface of the rolling element may have an additional advantage. When the lubrication is insufficient, a temperature of the rolling element may increase which causes the supply channel to increase while the viscosity of the lubricant may reduce. The dimensions of the supply channel may be chosen such that an increase of temperature of the rolling element causes a surplus of lubricant to be released from the rolling element, thus generating a substantially self-regulating control mechanism.

In an embodiment of the rolling element, the supply channel is open to the outer surface of the rolling element through a supply opening for supplying lubricant, the supply opening being located at a part of the outer surface of the rolling element where lubrication is required in operation. As indicated before, this location of the supply opening may, for example, be at the contact area between the rollng element and the raceway. Especially when the rolling element is an elongated rolling element, such as a cylindrical rolling element or a tapered rolling element, the position of the supply opening may be very well defined during operation. This results in a very accurate deposition of the lubricant during operation.

In an embodiment of the rolling element, the at least one channel is connected to a hollow structure at least partially surrounded by the first printed material. This hollow structure may be a storage element for storing lubricant. When the at least one channel is the extraction channel, the extraction channel may extract the accumulated surplus of lubricant, for example, via the capillary effect nto the extraction channel. This extracted lubricant will then be deposited into the hollow structure. When the at least one channel is the supply channel, the supply channel is connected to the hollow structure and the lubricant required at the outer surface of the rolling element will flow from the hollow structure via the supply channel to the surface of the rolling element. In an embodiment in which the first printed materia comprises both the extraction channel and the supply channel, a flow of lubricant may be generated. In such an embodiment, the surplus and accumulated lubricant may be extracted using the extraction channel and may be delivered by the extraction channel into the hollow structure. Subsequently the stored lubricant may be deposited from the supply channel to the surface of the rolling element and contribute to the smooth operation of the rolling element inside the bearing. In use, this deposited lubricant may migrate to the position inside the bearing where the extraction opening is located, where the accumulated lubricant is again extracted into the hollow structure. In such a way, and active pumping of lubricant through the bearing may be achieved.

The rolling element according to the invention may also comprise a plurality of hollow structures or lattice structures inside the rolling element which may be connected, for example, to distribute the lubricant inside the rolling element.

In an embodiment of the rolling element, the hollow structure comprises a lubricant sponge for storing lubricant material in the hollow structure. Such lubricant sponge may be constructed of a metal sponge in which the lubricant may be contained.

The dimensions of the extraction channel and/or supply channel may be chosen such that the active pumping of lubricant may be achieved in the bearing, for example, when the bearing is rotating at a specific predefined rotation speed. However, to prevent the lubricant to simple leak out of the hollow structure, for example, when the bearing is not rotating, the hollow structure may comprise the lubricant sponge. This lubricant sponge may also be used to store a surplus of lubricant to ensure the lubrication of the bearing during the lifetime of the bearing.

In an embodiment of the rolling element, the lubricant sponge comprises a material selected from ferrous alloys, non-ferrous alloys, amorphous oleophilic materials and crystalline oleophilic materials. The ferrous alloys may include steel and cast irons; the non-ferrous alloys may include titanium. Crystalline or amorphous structures may be produced in a 3D manufacturing process and may provide additional features, for example, a reduction in corrosion and deformations of the lubricant sponge. The amorphous structures may be useful when additional stiffness would be required.

In an embodiment of the rolling element, the rolling element comprises an outer casing at least partially forming the outer surface of the rolling element, the first printed material being bonded to the outer casing. This outer casing may, for example, comprise ring-shaped element which may, for example, be constituted of hardened steel to ensure that the material may withstand the wear and friction implied to the rolling element in use. In such an embodiment, the ring-shaped element may be a pre-fabricated ring-shaped element in which the first printed material is added to construct the rolling element according to the invention. Alternatively, the outer casing may be produced using a second printed material which is different from the first printed material, for example, in that the second printed material may be material which may be able to withstand the wear and friction acting on the rolling element in use.

In an embodiment of the rolling element, the opening to the outer surface of the rolling element of the extraction channel is an extraction bore ending at the extraction opening through the outer casing. Using the extraction bore allows the extraction channel to extract lubricant through the outer casing from the outer surface of the rolling element. In an embodiment of the rolling element the opening to the outer surface of the rolling element of the supply channel is a supply bore ending at the supply opening through the outer casing. Using the supply bore allows the supply channel to supply lubricant through the outer casing toward the outer surface of the rolling element.

In an embodiment of the rolling element, the hollow structure comprises a control system configured and constructed for releasing lubricant after receiving a trigger. The hollow structure inside the rolling element may be used to provide additional volume to position the control system without the need for additional volume inside the bearing. Such control system may be used, for example, as a safety system in which, for example, a sensor may indicate that there may be an emergency situation to trigger the safety system. For example, the temperature inside the bearing exceeds a predefined level, or the rolling of the rolling element inside the bearing is insufficient, or even the bearing stops rotating all together. During such emergency situations, access of lubricant may be required, and the safety system may provide such access of lubricant to the bearing.

The control system may also be used to sense and indicate when maintenance is required for the bearing. Regular maintenance is currently scheduled based on experience together with a safety margin to have the maintenance done before, for example, damage to the bearing occurs. However, in wind turbines, such maintenance may be very costly and labor extensive. Reducing the required maintenance would provide significant cost savings. Furthermore, sensing that maintenance is required for a bearing before the actually scheduled maintenance may prevent damage to the bearing. So the control system according to the invention may be incuded inside the bearing to sense a condition of the bearing, for example, a quality of the lubricant or an internal temperature of the rolling element, in use, or any other parameter. Subsequently, the control system may be configured br communicating the operating condition of the bearing to the outside such that the maintenance may be scheduled when necessary. Alternatively, the control system is configured to determine when the schedule would be necessary and provide a signal to the outside only when the maintenance is necessary.

In an embodiment of the rolling element, the control system comprises a cartridge comprising the lubricant or comprising the cartridge comprising chemicals for releasing the lubricant from the lubricant sponge. In case of an emergency, the cartridge may be broken to release the lubricant or release the chemicals such that the access of lubricant is provided to the bearing and the bearing may still be able to operate for a predefined period of time. For example, when the bearing is used in a wheel of an airplane any problem with the bearing during the landing of the airplane may result in a catastrophe. When the control system is a safety system able to provide the bearing with the access of lubricant such that the bearing is operates during the landing of the airplane, the catastrophe may be avoided. Subsequently, the bearing may need to be replaced, which may, for example, be communicated to the outside by the control system.

In an embodiment of the rolling element, the control system comprises a controller for receiving the trigger and for activating the release of lubricant. Such controller may receive the trigger from outside the bearing, for example, via a wireless signal. Alternatively, the control system may have a sensor on board, again inside the rolling element, for providing some trigger to the controller. The controller may also emit a further trigger, for example, indicating that the control system or safety system has been triggered and that the bearing, or at least the rolling element, needs to be replaced.

In an embodiment of the rolling element, the safety system further comprises a sensor connected to the controller. Such sensor may, for example, comprise a temperature sensor for sensing a quick rise in temperature to indicate that the bearing may get damaged soon, or for sensing a gradual increase of temperature which may be an indicator that maintenance may be required at some predefined point.

Other sensors may, for example, be oxidation sensors, chemical reacting tags, and lab-on-a-chip sensors. The sensor may be inside the control system and directly connected to the controller, or the sensor may be located outside the control system such that the sensor may be wirelessly connected to the controller.

The bearing in accordance with the second aspect of the invention comprises the ring according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. In the drawings, Fig. 1A shows a cross-sectional view of a first embodiment of a rolling element for a bearing according to the invention, Fig. 19 shows a cross-sectional view of a second embodiment of the rolling element for the bearing according to the inventon, and Fig. 1C shows a cross-sectional view of a third embodiment of a rolling element in the form of a sphere for a bearing according to the invention, Fig. 2 shows a cross-sectional view of a fourth embodiment of the rolling element for the bearing according to the invention, in which the rolling element comprises control system, Fig. 3 shows a plan view of a bearing according to the invention, partially cut open, Fig. 4A shows a first embodiment of an additive manufacturing tool in which a liquid resin is used for applying the printed material in the additive manufacturing process, Fig. 49 shows a second embodiment of the additive manufacturing tool in which a liquid resin is dispensed from a dispenser for applying the printed material in the additive manufacturing process, Fig. 5A shows a third embodiment of the additive manufacturing tool in which the material is granulated into small solid particles which are used for applying the printed material in the additive manufacturing process, Fig. SB shows a fourth embodiment of the additive manufacturing tool in which the granulated solid material is dispensed from a dispenser for applying the printed material in the additive manufacturing process, and Fig. 6 shows a fifth embodiment of the additive manufacturing tool in which a melted plastic material is dispensed for applying the printed material in the additive manufacturing process.

It should be noted that items which have the same reference numbers in different Figures, have the same structural features and the same functions, or are the same signals. Where the function and/or structure of such an item has been explained, there is no necessity for repeated explanation thereof in the detailed description.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1A shows a cross-sectional view of a first embodiment of a rolling element 100 for a bearing 300 according to the invention. The rolling element 100 is at least partially constituted of a first printed material 105 being material printed via an additive manufacturing process. The first printed material 105 comprises at least one channel 110, 120 open to an outer surface of the rolling element 100, in which the channel 110, 120 is configured and constructed to transport, in use, lubricant. The at least one channel 110, 120 may, for example, be an extraction channel 110 having an extraction opening 115 to the outer surface of the rolling element 100 for extracting lubricant from the outside of the rolling element 100 into the extraction channel 110.

Such extraction may be possible by designing the dimensions of the extraction channel to allow the extraction of lubricant via a capillary effect. In the embodment shown in Fig. 1A, the extraction channel 110 is connected to a hollow structure 130 which comprises a lubricant sponge 135 for storing lubricant. Next to the extraction channel 110, the at least one channel 110, 120 may be a supply channel 120 for supplying lubricant from the supply channel 120 via the supply opening 125 to the cuter surface of the rolling element 100.

In operation, the lubricant may be supplied from the supply channel 120 via the supply opening 125 to the outer surface of the rolling element 100. In use, the supplied lubricant may migrate through the bearing 300, for example, from a position inside the bearing 300 where the lubricant is required to a position inside the bearing 300 where the lubricant is not required or even where the lubricant is preferably not present as the presence of lubricant would result in an increase of dragging forces.

This migrated lubricant or this access of lubricant may be extracted from the outer surface of the rolling element 100 via the extraction opening 115 and the extraction channel 110. This extraction channel 110 may be designed such that the lubricant will be extracted from the surface via the capillary effect. The extracted lubricant may subsequently be deposited in the hollow structure 130 inside the rolling element 100.

As such, the lubricant is transported within the bearing 300 in a controlled environment while ensuring that sufficient lubricant is present at the interface between the rolling element 100 and, for example, a raceway of the inner ring 320 (see Fig. 3) or the outer ring 310 (see Fig. 3) and while preventing an access of lubricant to accumulate at locations where the lubricant is not wanted.

Fig. 1 B shows a cross-sectional view of a second embodiment of the rolling element 150 for the bearing 300 accordng to the invention. This second embodiment of the rolling element 150 also comprises a hollow structure 180 having an lubricant sponge 185, and comprises the extraction channel 160 with an extraction opening 165 and the supply channel 170 with the supply opening 175 to the outer surface of the rolling element 150.

In the embodiment shown in Fig. 1 B, the first printed material 155 is surrounded by an outer casing 190. This outer casing 190 may be produced from second printed material 190 printed via the additive manufacturing process. This second printed material 190 may, for example, have a higher durability or may be able to withstand more wear compared to the first printed material 155. The first printed material 155 may be printed on top of the second printed material 190. However, when also printing the second printed material 190, the deposition of the first printed material on the second printed material 190 may generate a functionally graded interface (not shown). The composition of such functionally graded interface layer is configured to gradually change from the first printed material 155 via a mixture of the first printed material 155 and the second printed material 190 to the second printed material 190. A benefit of such functionally graded interface layer is that the bonding between the first printed material 155 and the second printed material 190 is relatively strong.

Alternatively, the second material 190 may be prefabricated via any other production process, for example, injection molding process or casting process. Even further alternatively, the second material 190 may be produced using a grinding process and may, for example, be constituted of hardened steel 190 to wthstand the high durability and wear required for the rolling element 150. As such, the outer surface of the rolling element 150 is constituted of hardened steel while the inside of the rolling element is constituted of the first printed material in which the at least one channel 160, 170 are created to transport, in use, lubricant. The supply opening 175 may be a supply bore 175 through the outer casing 190 and the extraction opening 165 may be an extraction bore 165 through the outer casing 190.

Fig. 1C shows a cross-sectional view of a third embodiment of a rolling element 200 in the form of a sphere 200 for a bearing 300 according to the invention.

Also in a sphere 200, the rolling element 200 may comprise the supply channel 220 having the supply opening 225 in the form of a supply bore 225 through the outer casing 240 which is arranged around the first printed material 205. The sphere 200 again comprises the hollow structure 230 together with the lubricant sponge 235 for supplying oil or other lubricants to the outer surface of the rolling element 200.

Fig. 2 shows a cross-sectional view of a fourth embodiment of the rolling element 250 for the bearing 300 accordng to the invention, in which the rolling element 250 comprises control system 260. The control system 260 may be configured and constructed for releasing lubricant after receiving a trigger (not shown). The trigger may come from a sensor 264 which may be nside the control system 260, or from a transmitter outside the control system 260 providing the trigger as a wireless signal. As indicated before, the hollow structure 280 inside the rolling element 260 may be used to provide additional volume to position the control system 260 without the need for additional volume inside the bearing 300. The control system 260 may be used, for example, as a safety system 260 which is configured for supplying access of lubricant to the inside of the bearing 300 during an emergency situation. In such an embodiment, the control system 260 may, for example, comprise a controller 262 and the sensor 264 in which the sensor 264, for example, senses a parameter which may be used as an indicate whether or not an emergency situation is eminent.

In such an emergency situation an access of lubricant may be required fast to prevent the bearing 300 to immediately malfunction. For such a reason, the control system 260 may comprise a cartridge 266 comprising the lubricant which may be released in case of the emergency. Alternatively, the cartridge 266 may comprise chemicals for releasing the lubricant from the lubricant sponge (not shown in Fig. 2) which might be present inside the hollow structure 280 next to the control system 260.

In case of an emergency, the cartridge 266 may be broken to release the lubricant or release the chemicals such that the access of lubricant is provided to the bearing 300 and the bearing may still be able to operate for a predefined period of time. For example, when the bearing 300 is used in a wheel of an airplane (not shown) any problem with the bearing 300 during the landing of the airplane or helicopter may result in a catastrophe. When the control system 260 is the safety system 260 able to provide the bearing 300 with the access of lubricant such that the bearing 300 operates during the landing of the airplane or helicopters, the catastrophe may be avoided.

Alternatively, the control system may be used to sense and indicate when maintenance is required for the bearing 300. Regular maintenance is currently scheduled based on experience together with a safety margin to have the maintenance done before, for example, damage to the bearing 300 occurs. However, in wind turbines (not shown), such maintenance may be very costly and labor extensive.

Reducing the required maintenance would provide significant cost savings.

Furthermore, sensing that maintenance is required for a bearing 300 befcre the actualy scheduled maintenance occurs may prevent damage to the bearing 300. So the control system 260 according to the invention may be included inside the bearing 300 to sense a condition of the bearing 300, for example, a quality of the lubricant or an internal temperature of the rolling element 250, in use, or any other parameter.

Subsequently, the control system 260 may be configured for communicating the operating condition of the bearing 300 cr of the rolling element 250 to the outside such that the maintenance may be scheduled when necessary. Alternatively, the control system 260 may be configured to determine when the maintenance would be necessary and provide a signal to the outside only when the maintenance is necessary.

The control system 260 may, for example, comprise a sensor 264. Such sensor 264 may, for example, comprise a temperature sensor 264 for sensing a quick rise in temperature to indicate that the bearing may get damaged soon, or for sensing a gradual increase of temperature which may be an indicator that maintenance may be required at some predefined point. Alternatively, the control system 260 may receive a signal from another component that has failed or is failing, or may receive a signal from another rolling element in which the control system 260 has already been triggered.

Even further alternatively, the control system 260 may receive the trigger from an overall control system or a user. For example, if a control system 260 may be triggered in a part of the application, all other critical areas may also be triggered to ensure that the emergency lubricated in done in synchronization. The sensor 264 may be inside the control system 260 and directly connected to the controller 262, or the sensor 264 may be located outside the control system 260 such that the sensor may be wirelessly connected to the controller 262.

Fig. 3 shows a plan view of a bearing 300 according to the invention, partially cut open. The bearing 300 shown in Fig. 2 is a ball-bearing 300 comprising rolling elements 305 being spheres 305. The bearing 300 comprises an inner ring 320 an outer ring 310, a cage 330, and a rolling element 200 according to the embodiments of the invention. When using the rolling elements 100, 150, 250 as shown in Figs. 1A, 1 B and 2 in a bearing 300 according to the invention, the bearing 300 may need to be adapted to comprise such cylindrically shaped rolling elements 100, 150, 250.

Fig. 4A shows a first embodiment of an additive manufacturing tool 400 in which a liquid resin 450 is used for applying the printed material 460 in the additive manufacturing process. Such additive manufacturing tool 400 comprises resin container 430 comprising the liquid resin 450. Inside the resin container 430 a platform 470 is positioned which is configured to slowly move down into the resin container 430.

The additive manufacturing tool 400 further comprises a laser 410 which emits a laser beam 412 having a wavelength for curing the liquid resin 450 at the locations on the printed material 460 where additional printed material 460 should be added. A re-coating bar 440 is drawn over the printed material 460 before a new layer of printed material 460 is to be applied to ensure that a thin layer of liquid resin 450 is on top of the printed material 460. Emitting using the laser 410 those parts of the thin layer of liquid resin 450 where the additional printed material 460 should be applied will locally cure the resin 450. In the embodiment as shown in Fig. 4A the laser beam 412 is reflected across the layer of liquid resin 450 using a scanning mirror 420. When in the current layer all parts that need to be cured, have been illuminated with the laser beam 412, the platform 470 lowers the printed material 460 further into the liquid resin 450 to allow the re-coating bar 460 to apply another layer of liquid resin 450 on top of the printed material 460 to continue the additive manufacturing process.

Fig. 4B shows a second embodiment of the additive manufacturing tool 401 in which a liquid resin 450 is dispensed from a dispenser 405 or print head 405 for applying the printed material 460 in the additive manufacturing process. The additive manufacturing tool 401 again comprises the resin container 430 comprising the liquid resin 450 which is fed via a feed 455 towards the print head 405. The print head 405 further comprises a print nozzle 415 from which droplets of liquid resin 450 are emitted towards the printed material 460. These droplets may fall under gravity from the print head 405 to the printed material 460 or may be ejected from the print nozzle 415 using some ejection mechanism (not shown) towards the printed material 460. The print head 405 further comprises a laser 410 emitting a laser beam 412 for immediately cure the droplet of liquid resin 450 when it hits the printed material 460 to fix the droplet of liquid resin 450 to the already printed material 460. The printed material 460 forming a solid object may be located on a platform 470.

Fig. SA shows a third embodiment of the additive manufacturing tool 500 in which the material is granulated into small solid particles 550 which are used for applying the printed material 560 in the additive manufacturing process. Now, the additive manufacturing tool 500, also known as a Selective Laser Sintering tool 500, or SLS tool 500 comprises a granulate container 530 comprising the granulated small solid particles 550. The printed material 560 is located again on a platform 570 and is completely surrounded by the granulated small solid particles 550. Lowering the platform allows a granulate feed roller 540 to apply another layer of granulated solid particles 550 on the printed material 560. Subsequently locally applying the laser beam 512 using the laser 510 and the scanning mirror 520 will locally melt the granulated solid particles 550 and connects them with each other and with the printed material 560 to generate the next layer of the solid object to be created. Next, the platform 570 moves down further to allow a next layer of granulated solid particles 550 to be applied via the granulate feed roller 540 to continue the next layer in the additive manufacturing process.

Fig. SB shows a fourth embodiment of the additive manufacturing tool 501 or SLS tool 501 in which the granulated solid material 550 is dispensed from a dispenser 505 or print head 505 for applying the printed material 560 in the additive manufacturing process. The additive manufacturing tool 501 again comprises the granulate container 530 comprising the granulated solid particles 550 which are fed via a feed 555 towards the print head 505. The print head 505 further comprises a print nozzle 515 from which granulated solid particles 550 are emitted towards the printed material 560. These solid particles 550 may fall under gravity from the print head 505 to the printed material 560 or may be ejected from the print nozzle 515 using some ejection mechanism (not shown) towards the printed material 560. The print head 505 further comprises a laser 510 emitting a laser beam 512 for immediately melting or sintering the solid particle 550 when it hits the printed material 560 to fix the solid particle 550 to the already printed material 560. The printed material 560 forming a solid object may be located on a platform 570.

Fig. 6 shows a fifth embodiment of the additive manufacturing tool 600 in which a melted plastic material 650 is dispensed for applying the printed material 660 in the additive manufacturing process. The additive manufacturing tool 600 shown in Fig. 6 is also known as Fused Deposition Modeling tool 600 or FDM tool 600. Now a plastic filament 630 is fed into a dispenser 610 or melter 610 via a filament feeder 640.

The dispenser 610 or melter 610 comprises an extrusion nozzle 615 for melting the plastic filament 630 to form a droplet of melted plastic material 650 which is applied to the printed material 660 where it hardens and connects to the already printed material 660. The dispenser 610 may be configured and constructed to apply the droplet of melted plastic 650 to the printed material 660 under gravity or via an ejection mechanism (not shown). The additive manufacturing tool 600 further comprises a positioning system 620 for positioning the dispenser 610 across the printed material 660.

Summarizing, the invention provides a rolling element 100 for a bearing.

The invention further provides the bearing. The rolling element being at least partially constituted of a first printed material 105 being printed via an additive manufacturing process, the first printed material 105 comprising at least one channel 110, 120 open to an outer surface of the rolling element, the channel being configured and constructed to transport, in use, lubricant. The rolling element may comprise a hollow structure 130 containing lubricant for supplying the outer surface of the rolling element with lubricant, in use.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

LISTING OF REFERENCE NUMBERS

Rolling element 100, 150, 200, Additive manufacturing tool 400, 401 250 Print head 405, 505 First printed material 105, 155, 205, Print nozzle 415, 515 255 Laser 410,510 Extraction channel 110, 160 Laser beam 412, 512 Supply channel 120, 170, 220, Scanning mirror 420, 520 270 Resin container 430 Hollow structure 130, 180, 230, Re-coating bar 440 280 Liquid resin 450 lubricant sponge 135, 185, 235 Feed 455, 555 Extraction opening 115, 165 Platform 470, 570, 670 Supply opening 125, 175, 225, SLS-tool 500, 501 275 Granulate container 530 Outer casing 190, 240, 290 Granulate feed roller 540 Control system 260 Granulate material 550 Controller 262 FDM-tool 600 Sensor 264 Melter 610 Cartridge 266 Extrusion nozzle 615 Bearing 300 Positioning construction 620 Outer ring 310 Filament 630 Inner ring 320 Filament feeder 640 Printed material 105, 155, 205, Liquid plastic 650 255, 460, 560,

Claims

CLAIMS1. A rolling element (100, 150, 200, 250) for a bearing (300), the rolling element (100, 150, 200, 250) being at least partially constituted of a first printed material (105, 155, 205, 255) being printed via an additive manufacturing process, the first printed material (105, 155, 205, 255) comprising at least one channel (110, 160; 120, 170, 220, 270) open to an outer surface of the rolling element (100, 150, 200, 250), the channel (110, 160; 120, 170, 220, 270) being configured and constructed to transport, in use, lubricant.
2. The rolling element (100, 150, 200, 250) according to claim 1, wherein the at least one channel (110, 160; 120, 170, 220, 270) is an extraction channel (110, 160) configured for drawing lubricant into the at least one channel (110, 160; 120, 170, 220, 270) from outside the rolling element (100, 150, 200, 250).
3. The rolling element (100, 150, 200, 250) according to claim 2, wherein the extraction channel (110, 160) is open to the outer surface of the rolling element (100, 150, 200, 250) through an extraction opening (115, 165) for drawing the lubricant, the extraction opening (115, 165) being located at a part of the outer surface of the rolling element (100, 150, 200, 250) where no lubricant is required in operation.
4. The rolling element (100, 150, 200, 250) according to claim 1, wherein the at least one channel (110, 160; 120, 170, 220, 270) is a supply channel (120, 170, 220, 270) configured for supplying lubricant to the outer surface of the rolUng element (100, 150, 200, 250) for, in use, lubricatng rolling elements (100, 150, 200, 250) in the bearing (300).
5. The rolling element according to claim 4, wherein the supply channel is open to the outer surface of the rolling element (100, 150, 200, 250) through a supply opening (125, 175, 225, 275) for supplyng lubricant, the supply opening (125, 175, 225, 275) being located at a part of the outer surface of the rolling element (100, 150, 200, 250) where lubrication is required in operation.
6. The rolling element (100, 150, 200, 250) according to any of the claims 1 to 5, wherein the at least one channel (110, 160; 120, 170, 220, 270) is connected to a hollow structure (130, 180, 230, 280) at least partially surrounded by the first printed material (105, 155, 205, 255).
7. The rolling element (100, 150, 200, 250) according to claim 6, wherein the hollowstructure (130, 180, 230, 280) comprises an lubricant sponge (135, 185, 235) for storing lubricant material in the hollow structure (130, 180, 230, 280).
8. The rolling element (100, 150, 200, 250) according to claim 7, wherein the lubricant sponge (135, 185, 235) comprises a material selected from ferrous alloys, non-ferrous alloys, amorphous oleophilic materials and crystalline oleophUic materials.
9. The rolling element (100, 150, 200, 250) according to any of the previous claims, wherein the rolling element (100, 150, 200, 250) comprises an outer casing (190, 240, 290) at least partially forming the outer surface of the rolling element (100, 150, 200, 250), the first printed material (105, 155, 205, 255) being bonded to the outer casing (190, 240, 290).
10. The rolling element (100, 150, 200, 250) according to claim 9 when dependent on claims 2 or 4, wherein the opening (115, 165; 125, 175, 225, 275) to the outer surface of the rolling element (100, 150, 200, 250) of the extraction channel (110, 160) is an extraction bore ending at the extraction opening (165) through the outer casing (190, 240, 290), and/or wherein the opening (115,165; 125, 175, 225, 275) to the outer surface of the rolling element (100, 150, 200, 250) of the supply channel (120, 170, 220, 270) is a supply bore ending at the supply opening (125, 175, 225, 275) through the outer casing (190, 240, 290).
11. The rolling element (100, 150, 200, 250) according to any of the claims 6 to 10, wherein the hollow structure (130, 180, 230, 280) comprises a control system (260) configured and constructed for releasing lubricant after receiving a trigger.
12. The rolling element (100, 150, 200, 250) according to claim 11, wherein the control system (260) comprises a cartridge (266) comprising the lubricant or comprising the cartridge (266) comprising chemicals for releasing the lubricant from the lubricant sponge (135, 185, 235).
13. The rolling element (100, 150, 200, 250) according to claim 11 or 12, wherein the control system (260) comprises a controller (262) for receiving the trigger and for activating the release of lubricant.
14. The rolling element (100, 150, 200, 250) according to claim 13, wherein the control system (260) further comprises a sensor (264) connected to the controller (262).
15. A bearing (300) comprising at least one rolling element (100, 150, 200, 250) according to any of the previous claims.