Spacer for Spacing Apart Balls in an Apparatus for Lapping And/Or Grinding Balls and Apparatus for Lapping And/Or Grinding Balls

This application claims priority to German patent application no. 10 2024 205 846.7 filed on Jun. 24, 2024, the contents of which are fully incorporated herein by reference.

The present disclosure relates to an apparatus for lapping and/or grinding balls and a spacer for spacing apart balls in an apparatus for lapping and/or grinding balls.

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.

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.

During the machining process in the apparatus for lapping and/or grinding balls, the balls may collide and be damaged as they run through the at least one ball groove.

It is therefore an aspect of the present disclosure to provide an apparatus for lapping and/or grinding balls which reduces the risk that the balls will come into contact with one another in the apparatus.

An apparatus for lapping and/or grinding balls is presented below. The apparatus has at least one disc with at least one encircling ball groove in which at least one ball can be accommodated. The ball can, in particular, be formed from metal, glass, wood, plastic, ceramics or a combination thereof. However, it is also possible that the apparatus has a first and a second disc. In this case, the first disc can be of stationary design, and the second can rotate relative to the first disc.

Preferably, the at least one disc can be oriented horizontally. In particular, if the apparatus has two discs, the discs can be arranged one above the other in the direction of gravity, the discs thus being oriented horizontally. Alternatively, if the apparatus has two discs, the discs can also be oriented vertically. In particular, the at least one disc can be designed for grinding and/or lapping the ball. Moreover, if the apparatus has two discs, the at least one ball groove can be formed both in the first and in the second disc. Alternatively, the at least one ball groove can be formed in just one disc.

It is also possible that the at least one disc is provided with more than one ball groove. For example, it is possible for two, three, or more ball grooves to be provided in the at least one disc. This enables more balls to be machined simultaneously. If a plurality of ball grooves is provided, these can preferably be arranged concentrically.

If the apparatus has two discs, it is furthermore possible for one of the discs to be provided with a recess for inserting and removing the balls in the apparatus. The recess can be in the form of a sector, a rectangle, an oval or the like.

The balls located between the discs can be set in motion by the rotation of the at least 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 or grinding 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 and/or that damage to the ball surface is reduced or even avoided. 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.

To reduce the risk that the balls come into contact with one another in the apparatus, the apparatus furthermore has at least one spacer, which has a main body with a pocket, in which a ball can be accommodated, wherein the pocket has a first diameter and a second diameter, wherein the first diameter is larger than the second diameter.

In particular, the pocket can extend through the main body. This enables the ball accommodated in the pocket to come into contact with the at least one disc through the spacer. By virtue of the fact that the ball is accommodated in the pocket of the spacer, it is possible to prevent two balls from colliding and being damaged. The use of the spacer is particularly advantageous in the case of ceramic balls because, due to the material properties of ceramics, the ceramic balls are subject to a higher risk of being damaged by a collision between two balls.

The risk of damage in the event of a collision between two balls can also rise with an increasing diameter and/or increasing mass of the balls. The apparatus described for grinding and/or lapping balls can therefore be used to particular advantage for balls with a diameter of 20 mm or more.

The spacer can be produced from a plastic. This can have the advantage of enabling prevention of damage to a ball in the case of contact with the spacer. The pocket of the at least one spacer can furthermore be a conical hole. This has the advantage that the spacer can adapt better to a decreasing diameter of the ball since, during grinding and/or lapping of the ball, the diameter may decrease in the course of machining.

Furthermore, the first diameter of the pocket can be based on a starting size of the ball to be machined in the apparatus, and the second diameter of the pocket can be based on a final size of the ball to be machined in the apparatus. It is thereby possible to ensure that, on the one hand, the ball can be accommodated in the pocket at the start of machining and, on the other hand, is still accommodated in the pocket at the end of machining.

In particular, the first, larger, diameter can be larger than the diameter of the ball at the start of machining. This enables the ball to be accommodated in the pocket. Furthermore, the second, smaller, diameter can be smaller than the diameter of the ball at the end of machining. This has the advantage of making it possible to prevent the ball from dropping through the spacer.

The spacer is preferably arranged in the apparatus in such a way that the second, smaller, diameter is at the bottom in the direction of gravity and the first, larger, diameter is at the top in the direction of gravity. By virtue of the fact that the pocket has a first, larger, diameter and a second, smaller, diameter and the smaller of the two diameters is arranged at the bottom, it is possible to prevent the spacer from dropping off the ball. By virtue of the fact that the spacer is arranged in such a way that the smaller diameter is at the bottom, the spacer can advantageously be raised together with the ball. This can also make it possible to reduce the risk of the spacer dropping off the ball.

The apparatus can preferably have at least one guide element for guiding the spacer. For example, the guide element can be designed to hold the spacer at a specified distance and/or position with respect to the at least one ball groove. This can make it possible to further reduce the risk of the spacer dropping off the ball.

The guide element can furthermore have a U-shaped profile, at least in some section or sections. In particular, a distance between the two limbs of the U-shaped profile can be adapted in such a way that the spacer can be guided between the two limbs of the U-shaped profile. This can make it possible to further reduce the risk of the spacer dropping off the ball.

Furthermore, a distance between a zone of support of a ball on at least one of the discs and/or the at least one ball groove and the at least one guide element can be adapted in such a way that the ball is freely rotatable in the spacer. By virtue of the ability of the ball to rotate freely in the spacer, grinding and/or lapping of the ball can be performed more uniformly.

In particular, jamming of the ball in the spacer can be prevented by an appropriate choice of distance between the zone of support of the ball on the lower disc and/or in the at least one ball groove and the guide element. Furthermore, the zone of support of the ball in the ball groove and/or on the disc can be dependent on the diameter of the ball and/or can change during the machining of the ball in the apparatus since the diameter of the ball is reduced during machining by the removal of material.

A thickness of the spacer can preferably be adapted to a size of an angle of contact of the at least one ball groove of the apparatus. In particular, the angle of contact can indicate in angular degrees and/or in percent the contact region in which the at least one ball groove surrounds the ball. For example, the thickness of the spacer can be chosen so that the spacer almost fills the region in which the ball is not surrounded by the at least one ball groove. This can have the advantage that the ball is surrounded substantially completely by the at least one ball groove and the spacer, thus making it possible to prevent two balls from colliding.

Depending on the apparatus, the contact region of the ball grooves with the ball can be between 25% and 95%, preferably between 30% and 90%, and the angle of contact can be between 100° and 330°.

According to another aspect, a spacer is provided for spacing apart balls in an above-described apparatus for lapping and/or grinding balls. In this case, the spacer has a main body which is provided with a pocket, in which a ball can be accommodated, wherein the pocket has a first diameter and a second diameter, wherein the first diameter is larger than the second diameter.

The spacer can be produced from a plastic. This can have the advantage of enabling prevention of damage to a ball in the case of contact with the spacer. The pocket can preferably be a conical hole. This has the advantage that the spacer can adapt better to a decreasing diameter of the ball since, during grinding and/or lapping of the ball, the diameter may decrease in the course of machining. The main body can furthermore have an outer lateral surface with a cylindrical shape. This can prevent two spacers from sliding on top of one another and thereby falling off the ball.

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.

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.

shows a schematic cross-sectional view through an apparatusfor lapping and/or grinding ballsaccording to a first embodiment. The apparatushas a first discand a second disc. At least one encircling ball grooveis formed in the first diskand at least one encircling ball grooveis formed in the second disc. It is also possible for each of the discs to be provided with more than one ball groove,, e.g. two, three, four or more. Of course, it is also possible for just one of the two discs,to be provided with one or more ball grooves,. If a plurality of ball grooves,is provided, these can preferably be arranged concentrically.

As can be seen in, the two discs,are arranged horizontally one above the other, and the second discis configured to remain stationary during use while the first discrotates relative to the second disc. The ballslocated between the discs,can be set in motion by the rotation of the one disc. As the balls roll on the surfaces of the ball grooves,or discs,, 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 ballsis gradually removed.

For inserting and removing the ballsinto and from the apparatus, it is possible, in particular, for the second discto be provided with a recess (not shown).

As already described above, the ballsare set in motion by the relative rotation of the discs,, and therefore there is also a risk that the ballswill come into contact with adjacent ballsin the apparatus. To prevent the ballscoming into direct contact with each other, a spaceris furthermore provided.

The spacer(see) has a main bodywith a through-pocketin which an individual one of the ballscan be accommodated. The outer lateral surface of the main bodyhas a cylindrical shape. The pockethas a first diameter Dand a second diameter D, wherein the first diameter Dis larger than the second diameter D. In this case, the pocketis preferably conical. To prevent a ballfrom being damaged in the case of contact with the spacer, the spaceris preferably produced from a plastic.

The spaceris arranged in the apparatusin such a way that the second, smaller, diameter Dis at the bottom (relative to the direction of gravity). By virtue of the fact that the pockethas a first, larger, diameter Dand a second, smaller, diameter Dand the smaller of the two diameters Dis arranged at the bottom, it is not so easy for the spacerto become detached from the ballsince it remains caught on the ball, or the ballis held by the spacer. It furthermore makes it possible for the ballto be raised together with the spacer.

The first, larger diameter Dof the pocketof the spaceris chosen in accordance with an initial size of the ball, wherein Dis larger than the diameter of the ball at the start of machining. Furthermore, the second, smaller, diameter Dof the pocketis smaller than the diameter of the ballat the end of machining. This makes it possible to prevent the ball from dropping through the spacer since, during grinding and/or lapping of the ball, the diameter may decrease in the course of machining. In addition, the second, smaller, diameter Dof the pocketmay nevertheless be chosen to be so large that the ballcan come into contact with the ball groovewithout resting against the spacer.

In, the spaceris being guided between the discs,during the operation of the apparatuswith the spacerresting partially on the lower disc. By virtue of the fact that the spaceris resting on the lower disc, the spacercan be held at a specified distance or a specified position with respect to the ball groovein the lower disc. That is to say that the discalso serves as a guide element for the spacer.

A distance between a zone of supportof the ballin the ball grooveand a point of support of the spaceron the discis selected in such a way that the ballis freely rotatable in the spacer. That is to say that, when the ballis accommodated in the ball grooveor when it is running in the ball groove, it has substantially no contact with the spacer. By virtue of the ability of the ballto rotate freely in the spacer, grinding and/or lapping of the ballcan be performed more uniformly. The zone of supportof the ballin the ball grooveis dependent on the diameter of the balland accordingly changes during the machining of the ballin the apparatussince the diameter of the ballis reduced during machining by the removal of material.

In, the thicknessof the spaceris adapted to a size of an angle of contact of the ball grooves,of the apparatus, wherein the total angle of contact is composed of the angle of contact-of the ball grooveformed in the upper discand the angle of contact-of the ball grooveformed in the lower disc. In particular, the angle of contact can indicate in angular degrees and/or in percent the contact region in which the ball groove or ball grooves,surrounds or surround the ball.

In, the thicknessof the spaceris chosen so that the spaceralmost fills the region in which the ballis not surrounded by the ball grooves,. Depending on the apparatus, the contact region of the ball grooves with the ball can be between 25% and 95%, preferably between 30% and 90%, and the angle of contact can be between 100° and 330°.

shows a schematic cross-sectional view through an apparatusfor lapping and/or grinding ballsaccording to a second embodiment. The apparatusindiffers from the apparatusinin that it has a guide elementfor guiding the spacer. For example, the guide elementcan be designed to hold the spacerat a specified distance and/or a specified position with respect to the ball groove,. In particular, the guide elementcan be arranged in such a way that the ball is freely rotatable in the spacer. In, the guide elementis designed as a U-shaped profile with a first limb, a second limband a central limb, wherein the distance between the two limbs,can be adapted in such a way that the spacercan be guided between the two limbs,.

In summary, it is possible to provide an apparatusfor grinding and/or lapping ballswith which the risk of the ballscoming into contact with one another in the apparatusis significantly reduced. In particular, the apparatuscan be suitable for ceramic ballssince ceramic balls have a higher risk of being damaged in the event they collide with one another.

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 spacers for lapping and/or grinding balls and apparatuses for lapping and/or grinding balls including such spacers.

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.

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.