DE102022129782A1 - Assembly process - Google Patents

Abstract

The present invention relates to an assembly method (1) for a linear unit, in particular for a linear guide (10; 20) or a screw drive. The linear unit is partially assembled (S1) in such a way that a rolling element channel (23a) is formed between at least two different components (20a, 20b; 21, 22). A rolling element channel width (B) is determined (S2) using a measuring device (30). On the basis of the determined rolling element channel width (B), rolling elements (40) are provided (S3) and the assembly is completed using the provided rolling elements (40) (S4).

Description

The present invention relates to an assembly method for a linear unit, in particular for a linear guide or a screw drive.

Many linear units are based on the movable support of two components relative to one another by rolling elements arranged between them. For example, in precision rail guides, two parallel rail parts each have a groove. The two grooves together form a rolling element channel in which balls or cylindrical rollers are arranged. A similar configuration is used in profile rail guides, with the rolling element channel being formed by a groove in a profile rail and a groove in a profile rail carriage running on the rail. In screw drives such as a ball screw, the rolling element channel does not run linearly, but rather in a spiral shape between the inner surface of a spindle nut and the corresponding screw of the ball screw.

A factor that is important for the performance of the corresponding linear unit is the preload applied to the components that are mounted so that they can move relative to one another. The preload is expressed, for example, in the force exerted on the rolling elements by the two components. The preload can have an impact on the rigidity, friction, material fatigue and/or the service life of the linear unit, among other things.

The preload is usually achieved by rolling elements that are arranged with an interference fit in the rolling element channel. In order to achieve this interference fit, the distance between the running surfaces in the rolling element channel can be varied on some linear guides even after assembly, allowing the user to adjust the preload. However, the design of such linear units is complex and the precise adjustment of the desired distance requires a great deal of experience and sensitivity. Therefore, the desired preload is usually set once by the manufacturer during assembly by specifically selecting oversized rolling elements.

In order to be able to select the rolling elements specifically with regard to a certain excess, it is necessary to know the width of the rolling element channel. This width varies due to manufacturing tolerances. Therefore, during assembly, the components or assemblies involved in the formation of the rolling element channel are measured separately. The width of the rolling element channel can then be derived from the measurements. However, measurement errors that occur when measuring the various components can add up. The rolling element channel width determined in this way is therefore subject to increased uncertainty.

As an alternative to measuring the components, test assemblies with different components and/or rolling element sortings are occasionally carried out. However, the reliable assessment of whether the selected rolling elements in conjunction with the selected components lead to the desired preload and the associated properties of the linear unit requires a high level of experience. In addition, an iterative procedure using test assembly is very complex.

It is therefore an object of the invention to provide an improved assembly method. In particular, it is an object of the invention to provide a low-complexity assembly method in which a rolling element channel width can be determined with high precision.

This object is achieved by an assembly method according to the independent claim.

Further developments are the subject of the dependent claims and the following description.

The assembly method for a linear unit, in particular a linear guide or a screw drive, according to a first aspect of the invention comprises: (i) partially assembling a linear unit such that a rolling element channel is formed between at least two different components; (ii) determining a rolling element channel width using a measuring device; (iii) providing rolling elements based on the determined rolling element channel width; and (iv) completing the assembly using the provided rolling elements.

Forming a rolling element channel in the sense of the invention is preferably the formation of a channel from at least two components, i.e. parts or assemblies. The channel formed in this way is expediently intended for receiving, in particular for guiding, rolling elements. It is preferred that the formulation "forming a rolling element channel" also includes the partial formation of a rolling element channel. Consequently, forming a rolling element channel can also be understood as forming a rolling element channel section.

A rolling element channel or section formed by the at least two components does not necessarily have to be closed along its circumference. Rather, the rolling element channel nal can be slotted in the longitudinal direction or can be designed to be at least partially open along a circumferential section. Such rolling element channels can be formed, for example, if additional cavities are provided between the two components in the area of the rolling element channel.

One aspect of the invention is based on the approach of at least partially assembling the linear unit before determining a width of a rolling element channel between at least two components of a linear unit, which are to be movably mounted relative to one another via rolling elements after the linear unit has been assembled. The linear unit is preferably assembled from its individual components or assemblies at least to the extent that the rolling element channel is formed between the at least two components. This then enables the width of the rolling element channel that has already been formed to be determined, for example by measuring directly on the rolling element channel that has been formed. In contrast to the conventional procedure in which the components involved in the formation of the rolling element channel - or more precisely: those components that have an influence on the rolling element channel width when the linear guide is assembled - are measured and the rolling element channel width is deduced from these multiple measurements, the rolling element channel width can be determined according to the invention with just a single measurement. This not only reduces the effort required to determine the rolling element channel width, but also increases the precision of the measurement. In particular, it is possible to avoid multiple measurement errors adding up. At the same time, only one measuring device is required, which is set up to determine channel widths in the order of magnitude of rolling element channels.

Preferred embodiments of the invention and further developments thereof are described below. These embodiments can be combined with one another as desired, unless this is expressly excluded.

A particularly reliable determination of the rolling element channel width can be achieved by determining the rolling element channel width using a tactile or fluid-based measurement. In such measurements, a measuring body contacts a wall of the rolling element channel, or a measuring fluid flows through the rolling element channel. Such measurements are often more robust than measurements based on electromagnetic or ultrasonic scanning. Electromagnetic or ultrasonic measurements are in principle conceivable for achieving greater precision; however, the associated effort can be disadvantageous.

A tactile or fluid-technical determination of the rolling element channel width can be carried out using a measuring mandrel. When determining the rolling element channel width, the measuring device is therefore expediently introduced at least partially, namely in particular at least a part of the measuring mandrel, into the rolling element channel formed.

For example, the rolling element channel width can be determined with particularly little effort using a measuring mandrel designed as an internal micrometer. However, it is preferred if the rolling element channel width is determined without contact. The rolling element channel width is therefore expediently determined pneumatically. For this purpose, a pneumatic measuring mandrel can be inserted at least partially into the rolling element channel. This allows the wall of the rolling element channel to be exposed to a measuring gas or gas mixture, such as air, emerging from the measuring mandrel. The rolling element channel width can be determined by evaluating the dynamic pressure.

Some linear units, in particular linear guides such as precision rail guides or profile rail guides, can have more than one rolling element channel in the fully assembled state, for example two or four rolling element channels. In such a case, it is expedient if at least one further rolling element channel is formed between at least two components during partial assembly. Depending on the design of the linear unit, these components can be identical to the components that form the rolling element channel to be measured. In principle, however, the at least one further rolling element channel can also be formed by one or more further (other) components.

Preferably, running surfaces formed by these two (further) components are positioned in the further rolling element channel at a predetermined distance from one another. In other words, the width of the at least one further rolling element channel is preferably predetermined. Knowing the width of the further rolling element channel, together with the determined rolling element channel width, enables the targeted provision of rolling elements both for the rolling element channel and for the further rolling element channel. For example, a play-free bearing of the components without preload can be achieved by selecting a rolling element diameter equal to the average of the predetermined distance and the determined rolling element channel width.

In order to be able to set the specified distance between the two running surfaces reliably and with little effort, little At least one standard body is installed or introduced into at least one further rolling element channel.

The additional rolling element channel can, for example, be at least partially filled with predetermined rolling elements. The predetermined rolling elements expediently have a diameter that corresponds to the predetermined distance. The use of predetermined rolling elements to adjust the running surface distance in the additional rolling element channel is particularly advantageous because in this case no further precautions are required that go beyond the usual assembly of the linear unit.

Alternatively, a test pin is inserted at least partially into the further rolling element channel. Such test pins are available with diameter graduations in the micrometer range.

In order not to distort the result of the determination of the rolling element channel width, the linear unit is preferably partially assembled in such a way that after the rolling element channel has been formed, a prestress-free assembly state is present. Depending on the number of rolling element channels of the linear unit, it may therefore be preferable that at least one further rolling element channel is not filled with rolling elements.

If the rolling element channel formed is not completely closed in the circumferential direction, measuring gas or gas mixture can escape radially from the rolling element channel when the rolling element channel width is determined pneumatically. If the amount of medium escaping in this way is too large, this can impair the reliability of the measurement. Therefore, in some cases it can be advantageous for the rolling element channel formed to be radially sealed at least in sections for determining the rolling element channel width. A radial escape of measuring gas or gas mixture from the rolling element channel when the rolling element channel width is determined pneumatically can thus be prevented or at least reduced.

A radial seal of the rolling element channel can be achieved with little effort by arranging a sealing element, for example a sealing lip, in a gap adjacent to the rolling element channel between the at least two components.

The actual preload between two rolling element-mounted components of a linear unit does not only depend on the rolling element size relative to the rolling element channel width. For example, the properties of the materials used also influence the preload. For particularly stiff components, even a small interference fit of the rolling elements in the rolling element channel can lead to a high preload, while a high preload is difficult to achieve even with a larger interference fit with elastic components.

In order to be able to reliably set a desired preload, it is therefore preferred if the rolling elements are provided on the basis of a stiffness of at least one of the at least two components in addition to the determined rolling element channel width. This stiffness can be determined, for example, by a simulation or by series of measurements carried out in advance on at least one of the components.

Conventional measuring devices used to determine channel widths are usually designed in a straight line. This presents a particular challenge when measuring a rolling element channel that is not straight, such as in a screw drive, or even makes it impossible to determine the rolling element channel width.

Therefore, in some cases, a measuring device that is at least partially helical is preferably used to determine the rolling element channel width. The measuring device for determining the rolling element channel width is then expediently introduced into the rolling element channel at least partially in a helical groove around a cylindrical body section of one of the at least two different components. The measuring device can thus in particular be screwed into the rolling element channel at least partially. The assembly method can therefore also be used to manufacture screw drives.

The invention is explained in more detail below with reference to figures. Where appropriate, elements with the same effect are provided with the same reference numerals. The invention is not limited to the embodiments shown in the figures - not even in terms of functional features. The previous description as well as the following description of the figures contain numerous features, some of which are summarized in the dependent subclaims. However, the person skilled in the art will also consider these features, as well as all other features disclosed above and in the following description of the figures, individually and combine them to form further useful combinations. In particular, all of the features mentioned can be combined individually and in any suitable combination with the assembly method according to the first aspect of the invention.

• 1 ein Beispiel einer Präzisionsschienenführung in einem Querschnitt;
• 2 ein Beispiel einer fertig montierten Profilschienenführung in einem Querschnitt;
• 3 ein Beispiel einer teilweise montierten Profilschienenführung in einem Querschnitt;
• 4 ein Beispiel einer teilweise montierten Profilschienenführung in einer Draufsicht;
• 5 ein Beispiel einer teilweise in einen Wälzkörperkanal einer Linearführung eingeführten Messvorrichtung in einem Querschnitt; und
• 6 ein Beispiel eines Montageverfahrens für eine Linearführung.

They show, at least partially schematically:

• 1 an example of a precision rail guide in a cross section;
• 2 an example of a fully assembled profile rail guide in a cross-section;
• 3 an example of a partially assembled profile rail guide in a cross section;
• 4 an example of a partially assembled profile rail guide in a plan view;
• 5 an example of a measuring device partially inserted into a rolling element channel of a linear guide in a cross section; and
• 6 an example of an assembly procedure for a linear guide.

1 shows an example of a precision rail guide 10 in a cross section. The precision rail guide 10 has two pairs of precision rails 11, 12 that are mounted so as to be movable relative to one another, between which rolling elements 40 are arranged in a rolling element cage 41. The precision rails 11 are mounted on a sliding table 15 with screws 14. The precision rails 12 are mounted on a base 17 with screws 16.

The precision rails 11, 12 of each pair each have a longitudinal guide groove on the sides facing each other. The guide grooves form rolling element channels 13 in which the rolling elements 40 are arranged. During the longitudinal movement of the precision rails 11, 12 of a pair - and thus also of the sliding table 15 and the base 17 - relative to each other, the rolling elements 40 can roll on running surfaces in the rolling element channels 13.

The sliding table 15 is U-shaped, with the legs 15a, 15b of the U-shaped sliding table 15 laterally enclosing the precision rail pairs. With the help of several threaded pins 18, which are screwed into threaded holes in one of the legs 15a and one of which is in 1 As shown, the precision rails 11, 12 of each pair are clamped against each other. This preload can be increased by screwing the threaded pins 18 further into the threaded hole. The preload can be reduced accordingly by screwing the threaded pins 18 further out of the threaded hole. The preload of the precision rail guide 10 can therefore also be adjusted after it has been installed using the threaded pins 18.

2 shows an example of a fully assembled profile rail guide 20 in a cross section. The profile rail guide 20 has a profile rail 21 and a carriage 22 that is movably mounted relative to it by means of rolling elements 40. The rolling elements 40 are arranged in rolling element channels 23 between the profile rail 21 and the carriage 22.

Since the rolling elements 40 roll on running surfaces in the rolling element channels 23 on both the profile rail 21 and the carriage 22 during a relative movement of the profile rail 21 and the carriage 22, the carriage 22 has return channels 24 for the rolling elements 40. In end caps of the carriage 22 (not shown), the rolling elements 40 can be diverted from the rolling element channels 23 into the return channels 24 and vice versa. This allows the rolling elements 40 to circulate during larger relative movements.

In the example shown, the rolling elements 40 are oversized compared to the rolling element channels 23. As a result, the carriage 22 and the profile rail 21 are clamped against each other. This preload has an influence on essential properties of the profile rail guide 20, for example on its rigidity, friction and/or material fatigue.

3 shows an example of a partially assembled profile rail guide 20 in a cross section. The profile rail guide 20 has a profile rail 21 and a carriage 22. Between the profile rail 21 and the carriage 22, rolling element channels 23a and further rolling element channels 23b are formed for guiding rolling elements 40. In the fully assembled state, the carriage 22 should be mounted so that it can be moved along the profile rail 21 by means of the rolling elements 40 (p. 2 ), whereby return channels 24 are provided in the carriage 22 for the return of the rolling elements 40. In the partially assembled state shown, however, only the other rolling element channels 23b are filled with rolling elements 40. The two rolling element channels 23a, on the other hand, are left empty.

The rolling elements 40 already arranged in the additional rolling element channels 23b serve as standard bodies, through which a distance d between the running surfaces of the additional rolling element channels 23b is specified. In the partially assembled state shown, the profile rail 21 and the carriage 22 are arranged in such a way that the rolling elements 40 arranged in the additional rolling element channels 23b rest against the running surfaces without pressure. As a result, the diameter of the rolling elements 40 defines the width of the additional rolling element channels 23b.

It is not necessary that the other rolling element channels 23b are completely filled with rolling elements 40. Rather, the specified distance d can also be reliably set if if the further rolling element channels 23b are only partially filled with rolling elements 40.

As an alternative to rolling elements 40, other standard bodies can also be used, for example test pins (cf. 4 ).

Due to the fixed dimensions of the profile rail 21 and the carriage 22, a certain rolling element channel width B is obtained for the empty rolling element channels 23a for a given width of the additional rolling element channels 23b. In the partially assembled state of the profile rail guide 20 shown, this rolling element channel width B can be easily determined by measuring with a measuring device (see. 4 ). Knowing the rolling element channel width B and the specified distance d allows the size of the rolling element channels 23a, 23b to be calculated in a state in which the carriage 22 is arranged centered on the profile rail 21. On this basis, rolling elements 40 of a suitable size can be selected in order to be able to realize a desired play or a desired interference fit of the selected rolling elements 40 in the rolling element channels 23a, 23b.

4 shows a partially assembled profile rail guide 20 in a top view. In the partially assembled state, a rolling element channel 23a formed by a profile rail 21 and a carriage 22 and a further rolling element channel 23b are each connected to a corresponding return channel at only one end by an end cap 25 of the carriage 22 (cf. 3 ). At the opposite end, the rolling element channel 23a and the further rolling element channel 23b are open.

A test pin 50 is at least partially inserted into the further rolling element channel 23b through the channel opening of the further rolling element channel 23b. The test pin 50 serves as a standard body to specify a distance between two running surfaces in the further rolling element channel 23b. Consequently, the test pin 50 completely fills the further rolling element channel 23b radially, at least in the area of the channel opening.

A measuring device 30 designed as a pneumatic measuring mandrel is at least partially introduced into the rolling element channel 23a through the channel opening of the rolling element channel 23a. With the help of the pneumatic measuring mandrel, a rolling element channel width of the rolling element channel 23a can be determined pneumatically.

5 shows an example of a measuring device 30 partially inserted into a rolling element channel 23a of a linear guide in a cross section. The measuring device 30 is designed as a pneumatic measuring mandrel with which a rolling element channel width B of the rolling element channel 23a can be determined pneumatically. For this purpose, air flows from openings 31 of the measuring mandrel into the rolling element channel 23a. Conclusions about the rolling element channel width B can then be drawn, for example, from the measurement of the dynamic pressure inside the measuring mandrel.

Because the dynamic pressure depends on how freely the air can flow out in the area around the measuring mandrel, in the present example the rolling element channel 23a is sealed by means of a sealing element 60. The sealing element 60 is arranged in a gap 26 between two different components 20a, 20b of the linear guide, between which the rolling element channel 23a is also formed. The components 20a, 20b can, for example, be a profile rail and a carriage or components or assemblies thereof if the linear guide is designed as a profile rail guide. Accordingly, the components 20a, 20b can be precision rails if the linear guide is designed as a precision rail guide. It is also conceivable that the components 20a, 20b are a spindle and a spindle nut or components or assemblies thereof if the linear unit is designed as a screw drive.

6 shows an example of an assembly method 1 for a linear unit, in particular for a linear guide or a screw drive.

In a method step S1, a linear unit is mounted in such a way that a rolling element channel is formed between at least two different components. Preferably, at least one further rolling element channel is also formed between these or further components of the linear guide. When forming the further rolling element channel, two running surfaces for rolling elements are preferably arranged in the further rolling element channel at a predetermined distance from one another. This can be achieved, for example, by introducing or installing one or more standard bodies in the further rolling element channel, such as rolling elements of a predetermined size, a test pin and/or the like.

In a further method step S2, a rolling element channel width of the rolling element channel formed is determined. This is done pneumatically, for example. For this purpose, a measuring device designed as a pneumatic measuring mandrel can be at least partially introduced into the rolling element channel formed.

If the rolling element channel formed is not largely closed along its circumference, for example along more than 90 % of its circumference (cf. 3 ), it can increase the measurement In order to ensure high accuracy in process step S2, it may be advantageous to seal the rolling element channel. For this purpose, a sealing element, for example in the form of a sealing lip, can be inserted into a gap between the two components, which opens into the rolling element channel, in process step S2 before the measurement. Alternatively, the sealing element can also be installed in process step S1 during partial assembly, in particular in the gap.

In a further method step S3, rolling elements are provided on the basis of the determined rolling element channel width. For example, rolling elements of a certain size can be selected in order to achieve a desired preload of the linear unit. When selecting the rolling elements, a rigidity of at least one of the components between which the rolling element channel and/or the further rolling element channel is formed is expediently also taken into account.

Accordingly, the assembly of the linear unit is completed in a further process step S4 using the rolling elements provided.

List of reference symbols

1

Assembly procedure

10

Precision rail guidance

11

Precision rail

12

Precision rail

13

Rolling element channel

14

screw

15

Sliding table

15a

leg

15b

leg

16

screw

17

Base

18

Threaded pin

20

Profile rail guide

20a

component

20b

component

21

Profile rail

22

Dare

23

Rolling element channel

23a

Rolling element channel

23b

Rolling element channel

24

Return channel

25

End cap

26

gap

30

Measuring device

31

Opening

40

Rolling elements

41

Rolling element cage

50

Test pin

60

Sealing element

S1-S4

Process steps

B

Rolling element channel width

d

Distance

Claims (12)

Assembly method (1) for a linear unit, in particular a linear guide (10; 20) or a screw drive, comprising: - partially assembling (S1) a linear unit such that a rolling element channel (23a) is formed between at least two different components (20a, 20b; 21, 22); - determining (S2) a rolling element channel width (B) using a measuring device (30); - providing (S3) rolling elements (40) on the basis of the determined rolling element channel width (B); and - completing (S4) the assembly using the rolling elements (40) provided. Assembly method (1) according to Claim 1 , wherein when determining the rolling element channel width (B) the measuring device (30) is at least partially inserted into the formed rolling element channel (23a). Assembly method (1) according to Claim 1 or 2 , whereby the rolling element channel width (B) is determined pneumatically. Assembly method (1) according to one of the preceding claims, wherein during partial assembly at least one further rolling element channel (23b) is formed between at least two components (21, 22) and running surfaces formed by these two components (21, 22) are positioned in the further rolling element channel (23b) at a predetermined distance (d) from one another. Assembly method (1) according to one of the preceding claims, wherein during partial assembly at least one standard body is installed or introduced into at least one further rolling body channel (23b). Assembly method (1) according to Claim 5 , wherein the further rolling element channel (23b) at least is partially filled with predetermined rolling elements (40). Assembly method (1) according to Claim 5 , wherein a test pin (50) is at least partially inserted into the further rolling element channel (23b). Assembly method (1) according to one of the preceding claims, wherein the linear unit is partially assembled in such a way that after the formation of the rolling element channel (23a) a prestress-free assembly state is present. Assembly method (1) according to one of the preceding claims, wherein the rolling element channel (23a) formed is radially sealed at least in sections to determine the rolling element channel width (B). Assembly method (1) according to Claim 9 , wherein a sealing element (60) is arranged in a gap (26) adjacent to the rolling element channel (23a) between the at least two components (20a, 20b; 21, 22). Assembly method (1) according to one of the preceding claims, wherein the rolling elements (40) are provided in addition to the determined rolling element channel width (B) also on the basis of a stiffness of at least one of the at least two components (20a, 20b; 21, 22). Assembly method (1) according to one of the preceding claims, wherein the measuring device (30) for determining the rolling element channel width (B) is introduced into the rolling element channel (23a) at least in sections in a helical groove around a cylindrical body section of one of the at least two different components (20a, 20b).

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