GB2521392A

GB2521392A - Method of producing a raceway ring, inner ring or outer ring, and raceway ring

Info

Publication number: GB2521392A
Application number: GB1322416.7A
Authority: GB
Inventors: Philipp Krebs; Sebastian Ziegler
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: GB201322416D0; WO2015091723A2; WO2015091723A3

Abstract

A raceway ring 212, 220 for a bearing 200 comprising printed material 250, 255, 260 is produced by the steps of: separating a ring-shaped part (130, fig 1A) from a metal tube (100, fig 1A), the ring-shaped part comprising a raceway surface, and generating an attachment element 245, (247 or 248, fig 3B) on the ring-shaped part for generating the raceway ring. Further machining of the raceway ring may be required for generating a specific shape of the raceway ring. The attachment element 245, (247 or 248, fig 3B) is configured to improve a bonding between printed material and the raceway ring and may comprise circumferential, axial or radial groove(s) and/or an array of indentations. The inner ring or outer ring comprises the raceway ring and added printed material by an additive manufacturing process, such as direct laser deposition, to the raceway ring. The printed material is used to customize the inner and outer shape of the bearing.

Description

METHOD OF PRODUCING A RACEWAY RING, INNER RING OR OUTER RING, AND RACEWAY RING

FIELD OF THE INVENTION

The invention relates to a method of producing a raceway ring for a bearing and a method of producing an inner ring or an outer ring for a bearing. The invention further relates to the raceway ring.

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 abject, 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 object 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, for which the currently available materials that are applied via the additive manufacturing process seem insufficient.

SUMMARY OF THE INVENTION

One of the objects of the invention is to provide a method of producing a bearing using additive manufacturing.

A first aspect of the invention provides a method of generating a raceway ring for a bearing comprising printed material according to claim 1. The raceway ring comprises a raceway surface being a hardened steel surface configured and constructed for guiding rolling elements of the bearing. A second aspect of the inventon provides a method of producing an inner ring or an outer ring for the bearing according to claim 10. A third aspect of the invention provides a raceway ring for an inner ring or an outer ring of a bearing according to claim 15. Embodiments are defined in the dependent claims.

The method in accordance with the first aspect of the invention comprises the steps of separating a ring-shaped part from a metal tube, the ring-shaped part having an internal surface facing a rotational axis of the ring-shaped part and an external surface facing away from the rotational axis of the ring-shaped part, the internal surface or the external surface comprising the raceway surface, and generating an attachment element on the ring-shaped part, the attachment element being configured and constructed for improving a bonding between printed material being material to be printed via an additive manufacturing process and the ring-shaped part.

The inventors have realized that a main requirement of the material when used in a bearing is to withstand wear and rolling contact fatigue due to the contact forces on the rolling elements of the bearing in use. To be able to withstand this wear and rolling contact fatigue, the raceway surface is typically produced from hardened steel. The current additive manufacturing processes cannot produce hardened metal material in line with the requirements of a rolling element bearing. So the inventors have realized that the use of a raceway ring manufactured according to the first aspect of the invention enables to have the relatively high wear and rolling contact fatigue requirements imposed on the raceway surface, while allowing printed material to be attached to the raceway ring for generating the required shape of the inner ring or outer ring for a bearing and to carry the structural loads on the bearing and transmit them to the bearing housing or the shaft. As such the shape of the inner ring and/or outer ring of the bearing may be generated using additive manufacturing and allowing all degrees of freedom to produce any shape of the inner ring or outer ring which is possible using additive manufacturing, while using the raceway ring comprising the raceway surface to ensure that the raceway surface is able to withstand the wear and rolling contact fatigue of the rolling elements. In the method according to the current invention, a raceway ring is produced by separating a ring-shaped part from a metal tube, in which this ring-shaped part comprises the raceway surface. The ring-shaped part further comprises attachment elements for improving a bonding between the printed material and the ring-shaped part. Using the metal tube and then separating the ring-shaped part to generate a raceway ring is a convenient way to produce such raceway ring, while the metal tube may either be produced from hardened metal or the ring that has been cut off may be hardened at a later stage to produce the raceway surface. The attachment elements are required to ensure that the bonding between the printed material and the ring-shaped part is strong enough.

Next to the wear and strength requirements of the raceway surface, the inventors have realized that there is another reason why the raceway surface is preferably not produced using additive manufacturing. A solid object produced via the additive manufacturing process typically has a granulate structure. This is caused by the printing process in which individual layers of resin or molten plastic or in which individual granulated solid particles are deposited in a layer by layer process. Having a raceway surface constituted of a granular structure would generate additional vibrations in the bearing in use, when the rolling elements roll over the granular structured surface. These additional vibrations usually cannot be tolerated and may cause additional wear and noise when using such a bearing. When using the raceway ring produced according to the method of the current invention, the raceway ring is produced from a metal tube which comprises the raceway surface. This raceway surface is constituted of smooth hardened steel which would prevent the additional vibrations in the bearing. Still, the attachment elements allow the addition of printed material as further structural elements to allow to shape the inner ring or outer ring of the bearing using additive manufacturing.

In an embodiment of the method, the method further comprises the step of machining the internal surface or the external surface for generating the raceway surface. The raceway surface may require a specific shape which, for example, matches the outer shape of the rolling elements to allow the rolling elements to smoothly roll over the raceway surface. Alternatively, the raceway surface may be inclined with respect to the rotational axis to withstand axial forces which may be applied to the outer ring or inner ring of the bearing.

In an embodiment of the method, the raceway surface comprises a contact area being an area of the raceway surface where the rolling elements, in use, contact the raceway surface, wherein the step of generating the attachment element comprises to only generate the attachment element outside the contact area. The attachment elements typically are elements to roughen the surface of the raceway ring at which the printed material is to be applied at a further manufacturing step. Still, the raceway surface should be smooth such that the rolling elements may smoothly roll over the raceway surface of the bearing in use, reducing the overall wear, vibrations and noise produced by the bearing. As such, it is beneficial when the attachment elements are not produced at the contact area of the raceway ring. Furthermore, the attachment elements may reduce the strength of the raceway ring which should be avoided at the raceway surface. Finally, any residual stress that may be in the raceway ring may be concentrated around the attachment elements, which again should be avoided at the raceway surface.

In an embodiment of the method, the raceway surface having a non-stressed area in circumferential direction between the contact area and an edge of the raceway ring, wherein the step of generating the attachment element comprises to only generate the attachment element at the non-stressed area. Although there seems to be always some residual stress in the raceway ring, also at the non-stressed area, when the residual stress is below a certain threshold, the area around the raceway surface typically is called non-stressed area". As indicated already above the presence of the attachment elements may reduce the strength of the overall inner ring or outer ring of the bearing. Only applying the attachment elements at the non-stressed area further ensures that the reduction of the overall strength is limited. The non-stressed area is an area where the stress is less than 25% of the surface stress resulting from the most loaded rolling element of the bearing in use. This level of 25% may, for example, be used for a rolling element and raceway surface with a crowning and/or logarithmic profile. In such an embodiment, the attachment elements preferably are located outside an additional width of the raceway surface which is about 2 times the half width of the contact ellipse of the contact of the most loaded rolling element with the raceway ring.

Beyond this distance, the stress should have decreased to below 25% of the surface stress In an embodiment of the method, the step of generating the attachment element comprises generating a circumferential groove in circumferential direction, and/or a radial groove in radial direction and/or an axial groove in axial direction, and/or an array of indentations of the raceway ring. Such grooves roughen the surface of the raceway ring to improve the bonding between the printed material and the raceway ring and/or generate a form closure between the printed material and the raceway ring.

In an embodiment of the method, the step of generating the attachment element comprises mechanically milling, grinding, turning, scratching, embossing, laser engraving and/or imprinting the attachment element. Such mechanical process may be relatively simply to apply and may be done during other machining processes that may need to take place, such as the machining of the shape of the raceway surface. In a further embodiment of the method, the step of generating the attachment element comprises chemically roughening a surface of the ring-shaped part via chemical surface treatment and/or etching surface treatment. Next to chemically etching for applying the attachment element, the etching surface treatment may, for example, also be applied through plasma etching.

In an embodiment of the method, the attachment element comprises a coating, and the step of generating the attachment element comprises applying the coating to at least a part of the ring-shaped part.

In an embodiment of the method, the step of machining for generating the raceway surface comprises hard turning the ring-shaped part. Hard turning is typically used when the ring-shaped part already comprises hardened material. For example, when the metal tube is of hardened material, also the ring-shaped part is hardened material and may be shaped using hard turning. A benefit when using hard turning is that the raceway surface resulting from this machining does not need additional hardening of the surface. Such additional hardening process often slightly changes a dimension of the raceway ring which may cause inaccuracies in the shape and dimensions of the raceway ring. A further benefit is that when hard turning is used, cooling fluids are typically not needed. Separating the ring-shaped part from a hardened metal tube and subsequently machining the ring-shaped part using hard turning generates a most accurate raceway ring and raceway surface while using the fewest process steps. In an alternative embodiment of the method, the step of machining for generating the raceway surface comprises turning the non-hardened ring-shaped part, together with a hardening step of the metal and grinding the surface.

The method in accordance with the second aspect of the invention is configured for producing an inner ring or an outer ring for the bearing using the raceway ring manufactured according to invention. The method of producing the inner ring or outer ring comprises the steps of: providing the raceway ring, and adding the printed material to the raceway ring via the additive manufacturing process for generating the inner ring or the outer ring. As indicated before, the use of the raceway ring ensures that the mechanical requirements of the bearing with respect to wear and rolling contact fatigue are met, while the addition of printed material to the raceway ring allows the inner ring or outer ring to benefit from the flexible manufacturing possibilities of the additive manufacturing process.

The additive manufacturing process may, for example, be selected from a list comprising stereo-lithography, selective laser sintering, selective laser melting, laminated object manufacturing, fused deposition modeling, selective binding, laser engineering net shaping, photo polymerization, direct laser deposition (preferred) and selective electron beam sintering. The printed material may, for example, be chosen from a list comprising steel, stainless steel, maraging steel, tool steel, low alloy steel, copper alloys, nickel alloys, cobalt alloys, aluminum, aluminum alloys, titanium, titanium alloys.

In an embodiment of the method, the step of adding the printed material comprising adding a printed flange to the raceway ring the printed flange being constructed and configured for, in use, at least partially supporting the rolUng elements of the bearing in a direction parallel to a rotational axis of the rolling element.

In an embodiment of the method, the step of adding the printed material comprises adding the printed material as a structural material for carrying a load for strengthening the inner ring or outer ring. This allows the bearing to carry larger radial and axial loads and increases the robustness of the bearing application. In a further embodiment of the method, the step of adding the printed material comprises adding the printed material as a press-fit element for fitting the inner ring to a shaft or the outer ring to a bore. Using printed material for generating the press-fit element allows to use a relatively standard bearing which may be adapted to fit a specific customized element. In a further embodiment of the method, the step of adding the printed material comprises adding the printed material as a support structure for supporting the bearing.

This allows realizing arbitrary shapes of the support structure not possible with classical machining and thereby optimizes weight and/or stiffness. In a further embodiment of the method, the step of adding the printed material comprises adding the printed material as a non-circular construction. Often the inner ring or outer ring of a bearing are produced using turning processes which typically result in rotation symmetric structures and constructions. Using the additive manufacturing process, any shape may be produced, including non-circular constructions.

The raceway ring in accordance with the third aspect of the invention comprises a raceway surface being a hardened steel surface configured and constructed for guiding rolling elements of the bearing, the raceway ring further comprising an attachment element being configured and constructed for improving a bonding between printed material being material to be printed via an additive manufacturing process and the raceway ring.

In an embodiment of the raceway ring, the raceway surface comprises a contact area being an area where the rolling elements, in use, contact the raceway surface, the attachment element being arranged outside the contact area.

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, Figs. 1 A and 1 B show different steps in the method of producng the raceway ring according to the invention, Fig. 2A shows a cross-sectional view of a bearing comprising printed material, Fig. 2B shows a cross-sectional view of a raceway ring comprising attachment elements, and Fig. 2C shows a plan view of printed material constructed around the raceway ring, Fig. 3A shows a cross-sectional view of a further bearing comprising printed material, Fig. 33 shows a cross-sectional view of a raceway ring for a balkbearing having different types of attachment elements, and Fig. 3C shows a part of a raceway ring indicating the non-stressed area of the raceway ring, 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. 43 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. SA 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. 53 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, and Fig. 7 shows a flow diagram showing several steps of the method of producing a raceway ring and of producing the inner ring or outer ring of a bearing.

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

Figs. 1 A and 1 B show different steps in the method of producng the raceway ring according to the invention. Fig. 1A shows metal tube 100 from which a ring-shaped part 110 is separated. This separation process may be done using any known separation process, such as laser cuffing, grinding, turning, hard turning, sawing and water-jet cuffing. This ring-shaped part 110 comprises an internal surface 120 facing the rotation axis A (indicated with a dashed line) and an external surface 130 facing away from the rotation axis A. Fig. 1 B shows a further detail of the ring-shaped part 110 which may subsequently be used to manufacture a raceway ring 210 (see Fig. 2 B).

Fig. 2A shows a cross-sectional view of a bearing 200 comprising printed material 250, 255, 260. The bearing 200 comprises rolling elements 205 in the shape of rollers 205 being substantially cylindrcal rolling elements 205 arranged between the inner ring 280 and the outer ring 290. However also other shapes of rolling elements 205 may be applied, such as tapered (not shown) or spherical (not shown). Both the inner ring 280 and the outer ring 290 comprise of a combination of a raceway ring 212, 220 and printed material 250, 255, 260.

The outer ring 290 comprises a relatively flat raceway ring 220 together with the printed material 290 which defines the outer shape of the bearing 200. This printed material 290 may, for example, be formed to fit a specific bore (not shown) or may have a shape with which the bearing 200 may be fixed to a specific structure (not shown). Due to the combination of the raceway ring 220 and the printed material 290, the outer ring 290 may guide the rolling elements 205 smoothly without too much wear or rolling contact fatigue, while allowing the outer dimensions of the bearing 200 to be shaped according to the specific requirements of this specific bearing 200. Thus allowing a high quality raceway surface 230 (see Fig. 2B) while allowing maximum flexibility regarding outer dimensions. At the interface between the raceway ring 220 and the printed material 260 attachment elements (not shown in Fig. 2A) are applied.

In the current embodiment, the inner ring 280 also comprises a raceway ring 212 which has a slanted surface 230 (also indicated as tapered surface see Fig. 2B) as raceway surface 230 with respect to the rotational axis A to withstand axial forces applied to the bearing 200. Such a slanted surface 230 may be generated by mechanical processing the ring-shaped part 110 as shown in Fig. 1 B. When the ring-shaped part 110 is constituted of hardened material, this mechanical processing may be done using a hard turning process. A benefit of using such hard turning process is that the dimensions of the resulting raceway ring 212 may be better controlled compared to using a non-hardened ring-shaped part 110 which is requires hardening to produce the raceway surface 230. Such hardening process may change the outer dimensions of the raceway surface 230. The inner ring 280 as shown in Fig. 2A again comprises printed material 255, 250 for defining an inner dimension of the bearing 200, for example, to ensure that the bearing 200 fits around a specific shaft (not shown).

Again, the combination of this raceway ring 212 together with the printed material 255, 250 allows to use a relatively standardized raceway ring 212 while customize the inner shape and dimension of the bearing 200.

The inner ring 280 as shown in Fig. 2A comprises the printed material 255 which is the printed flange 255 which is constructed and configured for, in use, at least partially supporting the rolling elements 205 of the bearing 200 in a directon parallel to the rotational axis A. In such an embodiment, the printed flange 255 may have a similar hatching structure as the remainder of the printed material 250. In an alternative embodiment, the flange 255 may be produced via the machining process of the ring-shaped part 110 such that it forms an integral part of the raceway ring 212. In such an embodiment, the flange 255 should have a similar structure and color as the raceway ring 212. Forces which the flange 255 may be able to withstand may be much larger when the flange 255 is produced via the machining process compared to the embodiment in which the flange 255 is constituted of printed material 255. However, when the strength of the printed material 255 is sufficient, the use of printed material 255 as the flange 255 would enhance the flexibility of the production of the bearing 200.

Fig. 2B shows a cross-sectional view of a raceway ring 210 comprising attachment elements 245. The attachment elements 245 may, for example, be an array of indentations 245 as shown in Fig. 2B. Alternatively, the attachment elements 245 may be one or more circumferential grooves 247 see Fig. 3B), and/or one or more radial grooves (not shown) and/or one or more axial grooves (not shown). Even further alternatively, the attachment elements 245 may be mechanically or chemically applied surface roughening elements (not shown) or even a coating 248 (see Fig. 3B). The attachment elements 245 may, for example, be applied to the opposite surface 240 being a surface of the raceway ring 210 arranged on the opposite side of the raceway surface 230.

Fig. 2C shows a plan view of printed material 270, 275 constructed around the raceway ring 220. The printed material 270, 275 comprises structural material 270 for ensuring that the shape of the raceway ring 220 remains stable during the use of the bearing 200. The printed material 270, 275 further comprises a support structure 275 for further enhancing the strength of the structural material 270. The structural material 270 and the support structure 275 may both be different printed materials 270, 275. For example, only using stronger (and usually more expensive) printed material where necessary, for example, as support structure 275 would reduce the overall cost of the bearing 200 while maintaining the required strength. Also the overall weight of the bearing 200 may be strongly influenced by the selection of the printed material 270, 275.

Fig. 3A shows a cross-sectional view of a further bearing 300 comprising printed material 350, 360. The bearing 300 shown in Fig. 3A is a ball-bearing 300 comprising rolling elements 305 being balls 305. The inner ring 380 comprises the raceway ring 310 having printed material 350 bonded to the raceway ring 310 using attachment elements (not shown). The outer ring 390 comprises the raceway ring 320 having printed material 360 bonded to the raceway ring 320 using attachment elements (again, not shown). As can be seen from Fig. 3A, the outer dimensions of the printed material 360 attached to the raceway ring 320 of the outer ring 390 may have any shape, for example, having the rectangular cross-sectional dimension as shown in Fig. 3A. In such a configuration as shown in Fig. 3A, the printed material 360 of the outer ring 390 may further comprise a bore 365, for example, for allowing screws or other attachment means to connect the outer ring 390 to a structural element (not shown).

Fig. 3B shows a cross-sectional view of the raceway ring 310 for the ball-bearing 300 shown in Fig. 3A. The cross-sectional view of this raceway ring 310 shows different types of attachment elements 247, 248 for bonding the printed material 360 (see Fig. 3A) to the raceway ring 310. One of the attachment elements 247 shown is a circumferential groove 247 which may be applied outside the contact area 335 of the raceway surface 330. The circumferential groove 247 shown in Fig. 3B is undercut which further improves the bonding compared to a straight groove. Furthermore, the additive manufacturing process allows printing into such undercut circumferential grooves 247. Another attachment element 248 shown is a coating 248, again applied outside the contact area 335 of the raceway surface 330. The cross-sectional view of Fig. 3B shows further attachment element 345 being indentations 345 applied to the opposite surface 340 of the raceway surface 330 of the raceway ring 310.

Fig. 30 shows a part of a raceway ring 310 indicating the non-stressed area 337, 370 of the raceway ring 310. The raceway ring 310 is viewed from the rotation axis A outward. The dashed lines in Fig. 3C indicate the contact area 335 and the non-stressed area 337 is arranged on the raceway surface 330 between the contact area 335 and the edge 375 of the raceway ring 310, and the non-stressed area 370 is arranged on the opposite surface 340 of the raceway surface 330, again between the contact area 335 and the edge 375 of the raceway ring 310.

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. 5A 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 Depositicn 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.

Fig. 7 shows a flow diagram 700 showing several steps of the method of producing a raceway ring 210, 212, 220, 310, 320 and of producing the inner ring 280, 380 or outer ring 290, 390 of a bearing 200, 300. In the method according to the inventon, the raceway ring 210, 212,220,310,320 is generated using the following steps: at step 710 a ring-shaped part 110 (see Fig. 1A) is separated from a metal tube (see Fig. 1 A) and at step 720 an attachment element is generated on the ring-shaped part 110. In an optional step, shown in step 740, the ring-shaped part 110 may be machined to generate the raceway surface 230, 330. Steps 710, 720 and the optional step 740 together form step 750 and may be used to generate the raceway ring 210, 212, 220, 310, 320. The inner ring 280, 380 or outer ring 290, 390 is produced using this step 750 for generating the raceway ring 210, 212, 220, 310, 320 and subsequently apply, in step 730, printed material 250, 255, 260, 270, 275, 350, 360 to the raceway ring 210, 212, 220, 310, 320.

Summarizing, the invention provides a method of producing a raceway ring 212, 220 for a bearing 200 comprising printed material 250, 255, 260, a method of producing an inner ring 280 or outer ring 290 of the bearing, and provides the raceway ring. The method according to the invention comprises the steps of separating a ring-shaped part from a metal tube, the ring-shaped part comprising a raceway surface, and generating an attachment element on the ring-shaped part for generating the raceway ring. Further machining of the raceway ring may be required for generating a specific shape of the raceway ring. The attachment element is configured to improve a bonding between printed material and the raceway ring. The inner ring or outer ring comprises the raceway ring and added printed material to the raceway ring. In use, rolling elements 205 are guided by the raceway ring, ensuring the required strength and wear.

The printed material is used to customize the inner and outer shape of the bearing.

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

Metal tube 100 Contact area 335 Ring-shaped part 110 Non-stressed area 337, 370 Internal surface 120 Edge 375 External surface 130 Additive manufacturing tool 400, Rotational axis A 401 Bearing 200, 300 Print head 405, 505 Rolling elements 205, 305 Print nozzle 415, 515 Raceway ring 210, 212, 220, Laser 410, 510 310,320 Laserbeam 412,512 Raceway surface 230, 330 Scanning mirror 420, 520 Opposite surface 240, 340 Resin container 430 Attachment element 245, 345, 247, Re-coating bar 440 248 Liquid resin 450 Indentations 245, 345 Feed 455, 555 Circumferential Groove247 Platform 470, 570, 670 Coating 248 SLS-tool 500, 501 Structural material 250, 260, 270, Granulate container 530 350, 360 Granulate feed roller 540 Printed flange 255 Granulate material 550 Support structure 275 FDM-tool 600 Printed material 250, 255, 260, Melter 610 270, 275, 350, Extrusion nozzle 615 360, 460, 560, Positioning construction 620 660 Filament 630 Printable material 450, 550, 650 Filament feeder 640 Inner ring 280, 380 Liquid plastic 650 Outer ring 290, 390

Claims

CLAIMS1. A method of generating a raceway ring (210, 212, 220, 310, 320) for a bearing (200, 300) comprising printed material (250, 255, 260, 270, 275, 350, 360), the raceway ring (210, 212, 220, 310, 320) comprising a raceway surface (230, 330) being a hardened steel surface configured and constructed for guiding rolling elements (205, 305) of the bearing (200, 300), the method comprising the steps of: -separating a ring-shaped part (110) from a metal tube (100), the ring-shaped part (110) having an internal surface (120) facing a rotational axis (A) of the ring-shaped part (110) and an external surface (130) facing away from the rotational axis (A) of the ring-shaped part (110), the internal surface (120) or the external surface (130) comprising the raceway surface (230, 330), and -generating an attachment element (245, 345) on the ring-shaped part (110), the attachment element (245, 345) being configured and constructed for improving a bonding between printed material (250, 255, 260, 270, 275, 350, 360) being material to be printed via an additive manufacturing process and the ring-shaped part (110).
2. The method according to claim 1, wherein the method further comprises the step of machining the internal surface (120) or the external surface (130) for generating the raceway surface (230, 330).
3. The method according to claim 1 or 2, wherein the raceway surface (230, 330) comprises a contact area (335) beng an area of the raceway surface (230, 330) where the rolling elements (205, 305), in use, contact the raceway surface (230, 330), wherein the step of generating the attachment element (245, 345) comprises to only generate the attachment element (245, 345) outside the contact area (335).
4. The method according to claim 1, 2 or 3, the raceway surface (230, 330) having a non-stressed area (337) in circumferential direction between the contact area (335) and an edge (375) of the raceway ring (210, 212, 220, 310,320), wherein the step of generating the attachment element (245, 345) comprises to only generate the attachment element (245, 345) at the non-stressed area (370).
5. The method according to claim 4, wherein the non-stressed area (337) is an area where the stress is less than 25% of the surface stress resulting from the most loaded rolling element (205, 305) of the bearing (200, 300) in use.
6. The method according to any of the previous claims, wherein the step of generating the attachment element (245, 345) comprises generating a circumferential groove (247) in circumferential direction, and/or a radial groove in radial direction and/or an axial groove in axial direction, and/or an array of indentations (245) of the raceway ring (210, 212, 220, 310, 320).
7. The method according to any of the previous claims, wherein the step of generating the attachment element (245, 345) comprises: -mechanically milling, grinding, turning, scratching, embossing, laser engraving and/or imprinting the attachment element (245, 345), and/or -chemically roughening a surface of the ring-shaped part (110) via chemical surface treatment and/or etching surface treatment.
8. The method according to any of the claims 1 to 5, wherein the attachment element (245, 345) comprises a coating (248), and the step of generating the attachment element (245, 345) comprises applying the coating (248) to at least a part of the ring-shaped part (110).
9. The method according to any of the claims 2 to 8, wherein the step of machining for generating the raceway surface (230, 330) comprises: -hard turning the ring-shaped part (110), or -turning the non-hardened ring-shaped part (110), together with a hardening step of the metal and grinding the surface.
10. A method of producing an inner ring (280, 380) or an outer ring (290, 390) for the bearing (200, 300) using the raceway ring (210, 212, 220, 310, 320) manufactured according to any of the claims 1 to 9, wherein the method of producing the inner ring (280, 380) or outer ring (290, 390) comprises the steps of: -providing the raceway ring (210, 212, 220, 310, 320), and -adding the printed material (250, 255, 260, 270, 275, 350, 360) to the raceway ring (210, 212, 220, 310, 320) via the additive manufacturing process for generating the inner ring (280, 380) or the outer ring (290, 390).
11. The method according to claim 10, wherein the additive manufacturing process is selected from a list comprising stereo-lithography, selective laser sintering, selective laser melting, laminated object manufacturing, fused deposition modeling, selective binding, laser engineering net shaping, photo polymerization, direct laser deposition (preferred) and selective electron beam sintering.
12. The method according to claim 10, wherein the printed material (250, 255, 260, 270, 275, 350, 360) is chosen from a list comprising steel, stainless steel, maraging steel, tool steel, low alloy steel, copper alloys, nickel alloys, cobalt alloys, aluminum, aluminum alloys, titanium, titanium alloys.
13. The method according to claim 10, 11 or 12, wherein the step of adding the printed material (250, 255, 260, 270, 275, 350, 360) comprising adding a printed flange (255) to the raceway ring (210, 212, 220, 310, 320), the printed flange (255) being constructed and configured for, in use, at least partially supporting the rolUng elements (205, 305) of the bearing (200, 300) in a direction parallel to a rotational axis of the rolling element (205, 305).
14. The method according to claim 10, 11, 12 or 13, wherein the step of adding the printed material (250, 255, 260, 270, 275, 350, 360) comprises: -adding the printed material (250, 255, 260, 270, 275, 350, 360) as a structural material (250, 260, 270, 350, 360) for carrying a load for strengthening the inner ring (280, 380) or outer ring (290, 390), -adding the printed material (250, 255, 260, 270, 275, 350, 360) as a press-fit element (350, 360) for fitting the inner ring (280, 380) to a shaft or the outer ring (290, 390) to a bore, -adding the printed material (250, 255, 260, 270, 275, 350, 360) as a support structure (275) for supporting the bearing (200, 300), and/or -adding the printed material (250, 255, 260, 270, 275, 350, 360) as a non-circular construction (360).
A raceway ring (210, 212, 220, 310, 320) for an inner ring (280, 380) or an outer ring (290, 390) of a bearing (200, 300), the raceway ring (210, 212, 220, 310, 320) comprising a raceway surface (230, 330) being a hardened steel surface configured and constructed for guiding rolling elements (205, 305) of the bearing (200, 300), the raceway ring (210, 212, 220, 310, 320) further comprising an attachment element (245, 345) being configured and constructed for improving a bonding between printed material (250, 255, 260, 270, 275, 350, 360) being material to be printed via an additive manufacturing process and the raceway ring (210, 212, 220, 310, 320).
16. The raceway ring (210,212,220,310,320) according to claim 15, wherein the raceway surface (230, 330) comprising a contact area (335) being an area where the rolling elements (205, 305), in use, contact the raceway surface (230, 330), the attachment element (245, 345) being arranged outside the contact area (335).