Ball guiding device for an apparatus for lapping and / or grinding balls
The ball guiding device facilitates uniform abrasion and high accuracy in ball machining by guiding balls through concentric grooves in a predetermined sequence, addressing inefficiencies in existing apparatuses through automated transfer and reduced friction.
Patent Information
- Application Number
- US19/237301
- Authority / Receiving Office
- US · United States
- Patent Type
- Applications(United States)
- Current Assignee / Owner
- Priority Date
- 2024-06-24
- Filing Date
- 2025-06-13
- Publication Date
- 2025-12-25
AI Technical Summary
Existing ball machining apparatuses face inefficiencies in achieving uniform abrasion and high geometrical accuracy due to manual transfer or laborious sorting of balls between ball grooves of varying diameters, leading to increased time consumption and rejection rates.
A ball guiding device that enables balls to move through multiple concentric ball grooves in a predetermined sequence using guide grooves with ramps and return sections, allowing for seamless transfer without manual intervention, supported by bearing elements for adaptability and reduced friction.
Ensures uniform abrasion and high geometrical accuracy of machined balls by maintaining a consistent sequence through the grooves, reducing the risk of damage and improving production efficiency.
Smart Images

Figure US20250387865A1-D00000_ABST
Abstract
Description
CROSS-REFERENCE
[0001] This application claims priority to German patent application no. 10 2024 205 849.1 filed on Jun. 24, 2024, the contents of which are fully incorporated herein by reference.TECHNOLOGICAL FIELD
[0002] The present disclosure relates to a ball guiding device for an apparatus for lapping and / or grinding balls.BACKGROUND
[0003] Balls can be used in various applications. Depending on the application, various requirements may be made on the geometrical properties and / or surface properties of the balls, e.g. the roundness of the ball, the surface roughness, the diameter tolerance and / or the form error of the ball, and this may be influenced, in particular, by the machining of the balls.
[0004] In order to machine the surface and / or geometry of balls, there are known apparatuses for lapping and / or grinding in which balls are machined between two concentric discs. At least one of the discs is provided with at least one ball groove, which guides the balls in the apparatus. In general, one of the discs is stationary, while the other rotates and thereby moves the balls through the at least one ball groove. The movement of the balls and / or of the disc can be used to machine the surface of the balls. For this purpose, a suitable grinding and / or lapping medium can be provided in at least one of the discs and / or the at least one ball groove, for example.
[0005] For reasons of efficient production, apparatuses for grinding or lapping balls have a plurality of ball grooves to enable several balls to be machined simultaneously. Normally, the plurality of ball grooves are arranged concentrically, and therefore they differ in diameter. However, the greater the diameter of a ball groove, the greater is the amount of material removed per revolution because the lengths of those grooves are greaer. Therefore the balls which are in the ball groove with the largest diameter undergo greater abrasion for a given number of revolutions in the apparatus than the balls that are in the ball groove with the smallest diameter.
[0006] To achieve as uniform an abrasion as possible of all the balls inserted into the apparatus and thus achieve a high geometrical and / or dimensional accuracy of all the balls machined, it is therefore advantageous to transfer the balls to different ball grooves after a predetermined time. For example, the balls in the ball groove with a smaller diameter can be transferred to the ball groove with the next-largest diameter and so on. To ensure that the ball sequence is maintained, the transfer can be performed manually, for example, but this involves a large amount of work and is very time consuming. As an alternative, transfer may be omitted, and the balls may be laboriously sorted according to size and shape after machining, and this likewise requires a large amount of time and may lead to a high rejection rate.SUMMARY
[0007] It is therefore an aspect of the present disclosure to provide a ball guiding device for a lapping and grinding machine for balls in which the individual balls perform the entire process of movement through the ball grooves of the discs in succession in the same sequence.
[0008] A ball guiding device for an apparatus for lapping and / or grinding balls is presented below. The apparatus has a first disc and a second disc. At least one disc has a first ball groove and a second ball groove for guiding the balls. In addition, the first disc has a recess into which the ball guiding device can be inserted. The recess can be in the form of a sector, a rectangle, an oval or the like.
[0009] The ball guiding device has at least one guide groove, which connects the first ball groove and the second ball groove of the apparatus in such a way that a ball can run through the first and the second ball groove directly in succession, wherein the at least one guide groove comprises a first ramp, which is configured to guide the ball out of the first ball groove, and a second ramp, which is configured to guide the ball into the second ball groove. In particular, the first ramp can have a positive slope, and the second ramp can have a negative slope or gradient.
[0010] In particular, the first disc can be of stationary design, and the second disc can rotate relative to the first disc. The discs can preferably be arranged one above the other in the direction of gravity, the discs thus being oriented horizontally. In particular, the first and / or second disc can be configured for grinding and / or lapping the ball.
[0011] Moreover, the first and the second ball groove can be formed both in the first and in the second disc. It is furthermore also possible for more than two ball grooves, e.g. three, four or even more than four, ball grooves to be provided in the first and / or second disc. This enables more balls to be machined simultaneously. If a plurality of ball grooves is provided, these can preferably be arranged concentrically.
[0012] The balls located between the discs can be set in motion by the rotation of one disc. As the balls roll on the surfaces of the ball groove or disc, a sliding movement of greater or lesser magnitude may occur, this being referred to as the lapping movement. In combination with appropriate lapping media, which can be inserted into the apparatus together with the balls, this lapping movement can play a decisive role in ensuring that the roundness error of the balls is gradually removed. Removal of the ball material means, in particular, that a ball diameter at the start of machining is larger than the ball diameter at the end of machining.
[0013] The ball guiding device has the advantage that the balls run through the ball grooves in succession in the same sequence without having to be transferred manually from one ball groove to the other.
[0014] The balls can be formed from metal, glass, wood, plastic, ceramics or a combination thereof, for example.
[0015] The at least one guide groove can comprise a first side element, a second side element and / or a bottom element, for example. The provision of side elements can improve lateral guidance of the balls in the ball guiding device.
[0016] In a case in which the apparatus has more than two ball grooves, the ball guiding device can preferably also be provided with a plurality of guide grooves. In particular, one guide groove can be provided for each additional ball groove provided in addition to the first and second ball groove. This makes it possible for the balls to run through all the ball grooves in succession in the same sequence without having to be transferred manually.
[0017] Furthermore, the first ramp can have a first ramp slope and a first ramp length, and the second ramp can have a second ramp slope and a second ramp length. Moreover, the first ramp slope can be equal to or different from the second ramp slope.
[0018] In addition or as an alternative, the first ramp length can be equal to or different from the second ramp length. This enables the balls to be guided into and / or out of the corresponding ball groove in such a way, for example, that a probability that the balls will come into contact and / or be damaged is reduced.
[0019] Furthermore, the ball guiding device can be supported in a free-floating manner on at least one of the discs of the apparatus. This enables the ball guiding device to adapt to any irregularities in the discs and / or the ball grooves.
[0020] The ball guiding device can preferably have at least one level intermediate section, which connects the first and the second ramp. This enables the balls to be transferred from the first to the second ball groove by the ball guiding device in a manner which is as uniform as possible.
[0021] Furthermore, the first and / or the second ramp can be formed on a bottom of the guide groove. For example, the provision of the ramp on the bottom of the guide groove enables the ball to be directly raised and thus guided out of the first ball groove and / or into the second ball groove.
[0022] However, it is also possible for the ball to be guided indirectly out of the first ball groove and / or into the second ball groove. For example, it is possible to provide a spacer, which is arranged around a ball and is configured to space apart two adjacent balls. For example, the provision of the ramp on the side of the guide groove enables the ball to be raised indirectly by raising the spacer. This can have the advantage of making it possible to ensure that a spacer arranged around a ball is taken along during the transfer from the first to the second ball groove.
[0023] The guide groove can preferably have at least one side wall, which is configured as a guide element for a spacer that is suitable for spacing apart two adjacent balls. The guide element can advantageously ensure that the spacer is not lost as it runs through the apparatus and that the balls do not come into contact.
[0024] In particular, the at least one side wall can have a first ramp, which is configured to guide the spacer out of the first ball groove, and / or can have a second ramp, which is configured to guide the spacer into the second ball groove. This can have the advantage of making it possible to ensure that a spacer arranged around a ball is taken along during the transfer from the first to the second ball groove.
[0025] For example, the at least one guide groove can have a bottom and at least one side wall, and the first ramp can be arranged on the bottom, and the at least one side wall can have a further ramp, which is configured to guide the spacer out of the first ball groove.
[0026] Furthermore, the further ramp can have a third ramp slope and a third ramp length, wherein the first ramp slope is equal to or different from the third ramp slope. This enables the balls to be guided into and / or out of the corresponding ball groove in such a way, for example, that a probability that the balls will come into contact and / or be damaged is reduced.
[0027] In addition or as an alternative, the first ramp length can be equal to or different from the third ramp length. This enables the balls to be guided into and / or out of the corresponding ball groove in such a way, for example, that a probability that the balls will come into contact and / or be damaged is reduced.
[0028] When viewed in the direction of circulation of the balls, the further ramp can preferably be configured to guide the spacer out of the first ball groove ahead of the ball. In other words, the ball can be guided out of the first ball groove with the aid of the spacer. For example, the spacer can be designed in such a way that, when the ball runs in the ball groove, the ball rotates freely in the spacer but can nevertheless be raised with the aid of the spacer. Since the ball can be guided out of the first ball groove with the aid of the spacer, it is advantageously possible to ensure that the spacer remains arranged around the ball. This makes it possible to avoid a collision between two balls, which might damage the balls.
[0029] Furthermore, the at least one side wall can comprise a fourth ramp, which is configured to guide the spacer into the second ball groove.
[0030] In particular, a profile of the first, second and / or further ramp can be linear or non-linear.
[0031] The ball guiding device can furthermore preferably have a return section, which is configured to guide the balls back from the second groove to the first groove, wherein the return section has a return groove, which runs at least partially via the ball guiding device. This enables the balls to be guided through all the ball grooves of the apparatus. For example, the balls can run through the ball grooves of the apparatus successively from the inside outwards and then subsequently be conveyed back to the innermost ball groove by the return section.
[0032] Furthermore, the ball guiding device can have at least one bearing element, which is configured to support the ball guiding device on one of the discs of the apparatus for lapping and / or grinding balls. The at least one bearing element can furthermore also be configured to enable a relative movement between the ball guiding device and the rotating disc of the apparatus. The at least one bearing element can be a sliding element, a roller, a ball, and / or a bearing, in particular a rolling bearing, for example. It is thereby advantageously possible to achieve support for the ball guiding device on the disc in a manner which involves as little friction as possible.
[0033] As a preferred possibility, a plurality of bearing elements may also be provided. In this case, the plurality of bearing elements may be of the same type and / or of different types. For example, the ball guiding device can be fitted with a plurality of bearings and rollers.
[0034] Furthermore, the ball guiding device can have at least one holding element, which is configured to hold the ball guiding device in the apparatus. The holding element may be, in particular, an overhanging holding nose or an overhanging projection, which is configured to interact with a guide slot provided in the disc in order to hold the ball guiding device in position.
[0035] A further aspect of the disclosure comprises a ball guiding device configured for use with an apparatus for lapping and / or grinding balls. The apparatus includes a first disc and a second disc, and the second disc has a first continuous groove and a second continuous groove for guiding the balls and a first wall separating the first continuous groove from the second continuous groove. The first disc has a recess exposing the first continuous groove and the second continuous groove. The ball guiding device comprises a body having a first guide groove having a first end insertable through the recess into the first continuous groove and a second end insertable through the recess into the second continuous groove and a raised central portion connecting the first end of the first guide groove to the second end of the first guide groove and configured to overlie the first wall. The first guide groove includes a first ramp extending from the first end of the first guide groove to the raised central portion of the first guide groove and configured to guide the balls out of the first continuous groove and a second ramp extending from the raised central portion of the first guide groove to the second end of the first guide groove and configured to guide the balls into the second continuous groove.
[0036] Further advantages and advantageous embodiments are indicated in the description, the drawings and the claims. In this context, the combinations of features indicated in the description and in the drawings are, in particular, purely illustrative, and therefore the features may also be present individually or in different combinations.BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a schematic perspective view of a portion of an apparatus for lapping and / or grinding balls having a ball guiding device according to a first embodiment of the present disclosure.
[0038] FIG. 2 is a plan view of a portion of the ball guiding device according to the first embodiment of the present disclosure.
[0039] FIG. 3 is a sectional elevational view through the apparatus of FIG. 1.
[0040] FIG. 4 is a partial perspective view of an upper side of the ball guiding device of FIG. 1.
[0041] FIG. 5 is a partial perspective view of a lower side of the ball guiding device of FIG. 1.DETAILED DESCRIPTION
[0042] The disclosure will be explained in greater detail below with reference to exemplary embodiments illustrated in the drawings. Here, the exemplary embodiments and the combinations shown in the exemplary embodiments are purely illustrative and are not intended to define the scope of protection of the disclosure. This is defined solely by the appended claims. In the text which follows, elements that are identical or functionally equivalent are denoted by the same reference signs.
[0043] A ball guiding device 1 for an apparatus 2 for lapping and / or grinding balls 4 is described with reference to FIGS. 1 to 5. In particular, the balls 4 can be ceramic balls. For the sake of clarity, just one ball is illustrated. However, the apparatus 1 is configured to machine several balls simultaneously. In particular, the number of balls accommodated in each ball groove can correspond to complete filling of the smallest-diameter ball groove.
[0044] The apparatus 2 has a first disc 8 and a second disc 6, wherein the second disc 6 is of stationary design and the first disc 8 rotates relative to the second disc 6. As can be seen in FIGS. 1 and 3, the discs 6, 8 are arranged one above the other, the discs thus being oriented horizontally.
[0045] The discs 6, 8 each have three concentrically arranged ball grooves 10 (continuous grooves) in which the balls 4 are accommodated during the machining process. The balls located in the ball grooves 10 between the discs 6, 8 can be set in motion by the rotation of one disc 6. As the balls 4 roll on the surfaces of the ball groove 10 or discs 6, 8, a sliding movement of greater or lesser magnitude may occur, this being referred to as the lapping movement. In combination with appropriate lapping media, which can be inserted into the ball grooves 10 together with the balls 4, this lapping movement can play a decisive role in ensuring that the roundness error of the balls 4 is gradually removed and / or that damage to the ball surface is reduced or even avoided.
[0046] In addition, the first disc 6 has a recess 12, into which the ball guiding device 1 is inserted. The recess 12 can be in the form of a sector, a rectangle, an oval or the like. The ball guiding device 1 has a base plate 15, in which a first guide groove 14, which connects the first ball groove and the second ball groove of the apparatus 2 in such a way that a ball can run through the first and the second ball groove directly in succession, and a second guide groove 16, which connects the second ball groove and the third ball groove of the apparatus 2 in such a way that a ball can run through the second and the third ball groove directly in succession, are formed.
[0047] The guide grooves 14, 16 each comprise a first side element 22, a second side element 24 and a bottom element 26. The bottom element 26 can be formed by the base plate 15, for example. Furthermore, the first and the second side element 22, 24 can be formed by a side wall 28. In particular, the side wall 28 can separate the first guide groove 14 from the second guide groove 16, the side wall thus serving as a side element 22, 24 both for the first guide groove 14 and the second guide groove 16.
[0048] In order to guide the balls out of the corresponding ball groove 10, the guide grooves 14, 16 comprise, at their beginning when viewed in the direction of circulation, a first ramp 20, which is configured to guide the balls 4 out of the ball groove 10. At their end when viewed in the direction of circulation, the guide grooves 14, 16 likewise comprise a second ramp 30, which is configured to guide the ball 4 into the adjacent ball groove 10. As can be seen in FIG. 4, the ramps 20, 30 are formed on the bottom element 26. A level intermediate section 32, which connects the first and the second ramp 20, 30, is provided between the ramps 20, 30 in each guide groove 14, 16.
[0049] Finally, the ball guiding device 1 also has a return section 18, which connects the third ball groove to the first ball groove, thus ensuring that the balls 4 are guided back to the first guide groove again after passing through the third guide groove 10. The return section 18 likewise has a first ramp 20 which guides the ball out of the third ball groove. The return section 18 has a return groove 35 which has a section 34 with a slope which conveys the balls 4 upwards. The return groove 35 then runs at least partially via the guide grooves of the ball guiding device 1. In order to guide the balls back into the first ball groove, the return groove 35 has a further section 36, which has a gradient via which the balls are guided back into the first ball groove. Together with the return section 18, the ball guiding device 1 enables the balls 4 to run several times through all the ball grooves in succession in the same sequence.
[0050] Furthermore, at least some of the balls 4 can be mounted in a spacer 38, which ensures that two balls do not come into direct contact. Particularly in the case of ceramic balls, it may be necessary to prevent two balls from colliding directly in order to avoid damage to the balls. In the case where the balls 4 have a spacer 38, which is arranged around the ball 4 and is designed in such a way that the ball accommodated in the spacer 38 is raised with the spacer 38 when the spacer 38 is raised, a guide element 40 for a spacer 38 is furthermore formed on the side elements 22, 24. The guide element 40 can advantageously ensure that the spacer is not lost as it runs through the apparatus and that the balls do not come into contact. In order to form the guide element 40, a recess 42 of U-shaped cross section, in which the spacer 38 can be guided, is formed in the side elements 22, 24.
[0051] In order to reliably take along the spacer 38 when the ball 4 is transferred from one ball groove to the other ball grooves, the guide element 40 can also be provided with a first and a second ramp 44, 46, thus enabling the spacer 38 to be guided out of the first ball groove and guided into the second ball groove.
[0052] Advantageously, when viewed in the direction of circulation of the balls, the ramps 44, 46 for the spacer 38 are designed in such a way that the spacer 38 is guided out of the ball groove ahead of the ball 4. For example, the spacer 38 can be designed in such a way that, when the ball 4 runs in the ball groove 10, the ball 4 rotates freely in the spacer 38 but can nevertheless be raised with the aid of the spacer 38. After the spacer 38 has been raised by the ramp 44, together with the ball 4, the ball 4 itself can then be raised with the aid of the ramp 20 until it is once again freely rotatable in the spacer 38.
[0053] When it is introduced into the adjacent ball groove, the process can take place in reverse. That is to say that, first of all, the ramp 30 can lower the ball 4 until the ball is held in the spacer 38. The spacer 38, together with the ball 4, is then guided via the ramp 46 into the second ball groove, while the ramp 46 lowers the spacer 38 until the ball 4 is once again freely rotatable in the spacer 38 when it is being guided in the ball groove.
[0054] Each ramp 20, 30, 44, 46 has a respective ramp slope, a respective ramp length and a respective ramp profile. The slope of the first and second ramp 20, 30 can be equal or different. The length of the first and second ramp 20, 30 can likewise be equal or different. The profile of the first and the second ramp 20, 30 can be linear or, alternatively, non-linear, e.g. exponential. Furthermore, the slope of the ramps 44, 46 can be equal or different. The length of the ramps 44, 46 can likewise be equal or different. The profile of the ramps 44, 46 can be linear or, alternatively, non-linear, e.g. exponential. The ramps 44, 46 for the spacer 38 can preferably have a different slope, a different length and / or a different profile in comparison with the first and second ramp 20, 30.
[0055] The ball guiding device 1 is mounted in a free-floating manner on the disc 8 of the apparatus 2, enabling it to adapt to any irregularities in the disc 8 and / or the ball grooves. For this purpose, the ball guiding device is supported on the disc 8 by means of a plurality of rolling bearings 48. Furthermore, a plurality of rollers 50 is also arranged on an underside of the base plate 15 of the ball guiding device, and these improve sliding of the ball guiding device 1 on the rotating disc 8.
[0056] In order to ensure the alignment between the guide grooves and the ball grooves, the ball guiding device furthermore has a plurality of holding elements 52 designed as overhanging projections, which interact with a guide slot provided in the disc 8 in order to hold the ball guiding device in position.
[0057] The ball guiding device can be produced from plastic or metal, for example. Furthermore, the ball guiding device can be produced by an additive production method, e.g. 3D printing, an injection moulding method, or some other suitable production method.
[0058] In summary, the ball guiding device has the advantage that the balls run through the first and second ball grooves in succession in the same sequence without having to be transferred manually from the first ball groove to the second ball groove. In addition, it furthermore also makes it possible to transfer balls that are provided with a spacer, together with the spacer, from a first ball groove to a second ball groove without the risk that the spacer will slip off the balls.
[0059] Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved ball guiding device for an apparatus for lapping and / or grinding balls.
[0060] Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.
[0061] All features disclosed in the description and / or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and / or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.LIST OF REFERENCE SIGNS1 ball guiding device
[0063] 2 apparatus
[0064] 4 ball
[0065] 6 disc
[0066] 8 disc
[0067] 10 ball groove
[0068] 12 recess
[0069] 14 guide groove
[0070] 15 base plate
[0071] 16 guide groove
[0072] 18 return section
[0073] 20 ramp
[0074] 22 side element
[0075] 24 side element
[0076] 26 bottom element
[0077] 28 side wall
[0078] 30 ramp
[0079] 32 intermediate section
[0080] 34 section
[0081] 35 return groove
[0082] 36 section
[0083] 38 spacer
[0084] 40 guide element
[0085] 42 recess
[0086] 44 ramp
[0087] 46 ramp
[0088] 48 rolling bearing
[0089] 50 roller
[0090] 52 holding element
Examples
Embodiment Construction
[0042]The disclosure will be explained in greater detail below with reference to exemplary embodiments illustrated in the drawings. Here, the exemplary embodiments and the combinations shown in the exemplary embodiments are purely illustrative and are not intended to define the scope of protection of the disclosure. This is defined solely by the appended claims. In the text which follows, elements that are identical or functionally equivalent are denoted by the same reference signs.
[0043]A ball guiding device 1 for an apparatus 2 for lapping and / or grinding balls 4 is described with reference to FIGS. 1 to 5. In particular, the balls 4 can be ceramic balls. For the sake of clarity, just one ball is illustrated. However, the apparatus 1 is configured to machine several balls simultaneously. In particular, the number of balls accommodated in each ball groove can correspond to complete filling of the smallest-diameter ball groove.
[0044]The apparatus 2 has a first disc 8 and a second di...
Claims
1. A ball guiding device configured for use with an apparatus for lapping and / or grinding balls, the apparatus including a first disc and a second disc, the second disc having a first continuous groove and a second continuous groove for guiding the balls and a first wall separating the first continuous groove from the second continuous groove and the first disc having a recess exposing the first continuous groove and the second continuous groove, the ball guiding device comprising:a body having a first guide groove having a first end insertable through the recess into the first continuous groove and a second end insertable through the recess into the second continuous groove and a raised central portion connecting the first end of the first guide groove to the second end of the first guide groove and configured to overlie the first wall, the first guide groove including a first ramp extending from the first end of the first guide groove to the raised central portion of the first guide groove and configured to guide the balls out of the first continuous groove and a second ramp extending from the raised central portion of the first guide groove to the second end of the first guide groove and configured to guide the balls into the second continuous groove.
2. The ball guiding device according to claim 1,wherein the raised central portion of the first guide groove is not sloped relative to the first disk.
3. The ball guiding device according to claim 2,wherein the first and / or the second ramp of the first guide groove are / is formed on a bottom of the first guide groove.
4. The ball guiding device claim 2,wherein the first guide groove includes a first portion configured to guide the balls and a channel portion running along the first portion of the first guide groove, the channel portion of the first guide groove being configured to guide a spacer element surrounding each of the balls.
5. The ball guiding device according to claim 2,wherein the second disk includes a third continuous groove and a second wall separating the third continuous groove from the first continuous groove,wherein the body has a second guide groove having a first end insertable through the recess into the second continuous groove and a second end insertable through the recess into the third continuous groove and a raised central portion connecting the first end of the second guide groove to the second end of the second guide groove and configured to overlie the second wall, the second guide groove including a first ramp extending from the first end of the second guide groove to the raised central portion of the second guide groove and configured to guide the balls out of the second continuous groove and a second ramp extending from the raised central portion of the second guide groove to the second end of the second guide groove and configured to guide the balls into the second continuous groove.
6. The ball guiding device according to claim 5,wherein the raised central portion of the second guide groove is not sloped relative to the first disk.
7. The ball guiding device claim 6,wherein the second guide groove includes a first portion configured to guide the balls and a channel portion running along the first portion of the second guide groove, the channel portion of the second guide groove being configured to guide a spacer element surrounding each of the balls.
8. The ball guiding device according to claim 1,including a return channel configured to guide the balls from the second continuous groove to the first continuous groove.
9. The ball guiding device according to claim 1,wherein the body includes a bearing element configured to contact the second disk and support the body on the second disk10. The ball guiding device according to claim 9,wherein the bearing element comprises a rolling-element bearing.
11. The ball guiding device according to claim 5,wherein the body includes a bearing element configured to contact the second disk and support the body on the second disk12. The ball guiding device according to claim 11,wherein the bearing element comprises a rolling-element bearing.
13. The ball guiding device according to claim 1 including at least one holding element configured to hold the ball guiding device in the apparatus.