Centering device and method for assembling such a centering device

Abstract

The invention relates to a centering device (10) comprising a piston rod (12), which can be adjusted in a piston rod housing (14), and centering elements (24), which interact with the piston, for adjusting same. The piston rod housing (14) has openings (26) for guiding the centering elements (24), which are interlockingly engaged with the piston rod. When the piston rod is axially adjusted in the direction of the distal end of the piston rod housing, the fixing elements being guided in the openings project circumferentially beyond the circumferential surface (30) of the piston rod housing (14).

Description

[0001] Description

[0002] Centering device and method for assembling such a

[0003] The invention relates to a centering device, in particular intended for centering a workpiece, comprising a piston rod adjustable in a piston rod housing, which is connected in the proximal region to a piston adjustable in a housing, and centering elements interacting with the piston rod for adjusting it, wherein the piston rod housing has openings in its distal region for guiding the centering elements, which engage positively with the piston rod such that, when the piston rod is axially adjusted, the fixing elements guided in the openings project peripherally beyond the circumferential surface of the piston rod housing, or extend peripherally aligned or substantially peripherally aligned with the circumferential surface, or the radially outermost region of each centering element lies on the cylindrical surface spanned by the piston rod housing or extends recessed from it.

[0004] The invention also relates to a method for assembling a centering device comprising a piston rod with a piston rod housing that receives it. Centering devices are clamping devices used to center components with receiving bores, which are then fixed in a clamping fixture and machined. Conventional centering devices can have clamping balls suitable for adjusting and precisely centering unmachined components. Centering devices with wedge surfaces are also known. However, regardless of the design of the centering device, problems arise when the receiving bores have diameters of less than 25 mm, particularly less than 15 mm.

[0005] A generic centering device can be found in DE 297 00 886 Ul.

[0006] DE 102 35 577 B4 relates to a positioning and clamping device which has a sliding jaw clamping mandrel with sliding jaws which are spread by means of a wedge-shaped widened drawbar head.

[0007] A spreading and pulling mandrel, which can be used in body construction in the automotive industry, is described in DE 10 2016 015 041 A1. An expanding mandrel is arranged axially displaceably in an axially adjustable centering mandrel, over which clamping jaws are radially adjustable.

[0008] US Patent 3,791,011 A relates to a pipe removal device from a flat support of a heat exchanger.

[0009] The present invention is based on the objective of further developing a centering device of the type mentioned above in such a way that workpieces with receiving bores in the range of less than 25 mm, and in particular also less than 15 mm, can be easily centered and clamped.

[0010] To solve the problem, the invention provides that the piston rod housing is closed distally by a removable locking element, and that openings are provided in the piston rod housing adjacent to the locking element.

[0011] Since the openings through which the locking elements pass are located directly below the locking element that distally closes the piston rod housing, a short design is achieved. This is because, even with the centering elements pushed outwards, the piston rod, with its distal end facing the locking element, runs in a plane defined by the distal portions of the centering elements or approximately in this plane, i.e., also directly below the inner surface of the locking element. When the piston rod is retracted, i.e., its distal end facing away from the locking element, the centering elements are retracted to either be flush with the outer surface of the piston rod housing or slightly offset inwards from it.

[0012] Since the centering elements penetrate the piston rod housing at the outermost end, workpieces with short bores can be centered and clamped without any problems.

[0013] The distance between a plane spanned by the apex areas of the openings through which the centering elements extend on the lid side and the plane spanned by the inside of the closure element, such as the lid, should be in the range between 0.65 mm and 2.00 mm, preferably between 0.65 mm and 1.5 mm.

[0014] The distance between the respective distal vertex area of ​​the openings penetrated by the centering elements and the outside of the closure element should be in the range between 2.25 mm and 5.00 mm, preferably in the range between 2.25 mm and 3.5 mm.

[0015] The outer surface of the locking element spans a plane that runs perpendicular to the longitudinal axis of the piston rod housing and should transition flush into the end face of the piston rod housing.

[0016] Preferably, the wall thickness of the piston rod housing in the area where the piston rod slides along the inner surface of the piston rod housing is between 1.85 mm and 5.8 mm.

[0017] In the distal region of the piston rod, its diameter is reduced, preventing contact with the inner surface of the piston rod housing. This reduces friction. Because the piston rod would otherwise slide along the inner surface of the piston rod housing, its guidance is maintained.

[0018] In the area of ​​the centering elements, specifically below them, the wall thickness of the piston rod housing is increased inwards, preferably to values ​​between 2.05 mm and 6.00 mm, in order to center the piston rod in this area, ensuring that the centering elements can be moved vertically to the longitudinal axis of the piston rod within the openings passing through the piston rod housing to the required extent with minimal friction and without the risk of jamming.

[0019] In particular, it is provided that the centering element is positively connected to the piston rod via a dovetail-like connection, wherein a pin element should extend from the centering element, which engages in a groove inclined to the longitudinal axis of the piston rod, or vice versa.

[0020] The pin preferably has the cross-sectional shape of an isosceles trapezoid, the shorter base leg of which extends from the body of the centering element. The groove running in the piston rod has lateral boundaries whose course corresponds to that of the lateral legs of the pin.

[0021] On the bottom side, the groove may have a longitudinal recess, with the bottom section potentially having a V- or U-shape in cross-section. This results in the longer base leg of the pin element being spaced away from the bottom surface of the groove, consequently requiring minimal frictional forces to be overcome during adjustment.

[0022] The positive locking connection between the centering element and the piston rod, and the guidance of the centering elements in the openings in the piston rod housing, makes it possible to easily adjust the centering elements transversely, and especially vertically, to the longitudinal axis of the piston rod, while simultaneously achieving large clamping forces.

[0023] In particular, the centering element is provided for in a centering or clamping piston with a cylindrical geometry, from whose inner end face the pin extends. The outer end face is geometrically adapted, at least in its edge region, to the circumferential surface of the piston rod housing, so that a flush transition can occur when the centering device is not intended to center.

[0024] The outer end face of the centering piston can also have the shape of a spherical segment. When viewed in the retracted (not in use) state, the outermost point of the end face, in the longitudinal direction of the centering piston, should lie within a bore on the circumferential surface, i.e., the outer surface of the piston rod housing, or possibly be slightly offset from it.

[0025] In particular, it is provided that the centering or clamping piston has a diameter Ds of 3.5 mm < Ds < 7 mm and / or the piston rod has a diameter DK of 6 mm < DK < 15 mm and / or the piston rod housing has a diameter DG of 9.00 mm < DG < 25.00 mm.

[0026] The centering device should have at least 2 or 3 centering elements that penetrate the openings arranged at equidistant intervals in the piston housing.

[0027] The longitudinal axes of the openings preferably run perpendicular to the longitudinal axis of the piston rod housing and thus of the piston rod.

[0028] When using three centering pistons or elements, the inner end face of each centering piston should have two first contact surfaces that form an angle of 120°. To insert the pins into the grooves of the piston rod, a first contact surface of one of the centering pistons rests against a first contact surface of the other centering pistons. This allows for simple assembly despite the small dimensions of the centering and clamping elements.

[0029] If more than 3 centering pistons are present, the inner end faces have correspondingly oriented end faces with a different enclosing angle.

[0030] If two centering pistons are present, a removable assembly aid is provided in the piston rod housing, extending along the longitudinal axis of the piston rod housing. The inner end faces of the centering pistons then rest against the assembly aid to facilitate the insertion of the pins into the grooves.

[0031] For this purpose, it is specifically provided that the assembly aid is a centering pin which has a first outer cylindrical section and a subsequent cylindrical inner section of smaller diameter, from which in turn a second outer section extends, having in cross-section an isosceles trapezoidal geometry or a triangular geometry.

[0032] The inner end faces of the centering pistons have a geometry such that the centering pistons have a recess in their inner end faces that is adapted to the geometry of the inner section of the assembly aid.

[0033] The second outer section is adapted to the shape of the outer surface of the pin, which is inclined to the longitudinal axis of the piston rod.

[0034] Thus, sections of the inner end faces of the centering pistons act as second contact surfaces against the assembly aid during assembly, providing a positive fit.

[0035] The centering pistons run in the distal area of ​​the piston rod.

[0036] In the proximal area, the piston rod is connected to a piston which is adjustably arranged in a base housing which in turn can be installed in a device or machine in which the workpiece centered by the centering device according to the invention is to be aligned.

[0037] The piston is adjustable in the base housing such that, in a first position, the grooves of the piston rod are aligned with the pins of the centering pistons, which lie with their first contact surfaces against each other, or, in the case of the second contact surfaces, against the assembly aid. When the pins are inserted into the grooves and the centering elements, such as pistons, preferably transition flush with the outer surface of the housing, or when the maximum radially extending area of ​​the centering elements lies on the circumferential surface spanned by the piston rod housing or is slightly offset from it, a stop, such as a snap ring, is installed in the base housing to prevent the piston from moving towards the first position.

[0038] The piston rod and the internal geometry of the piston rod housing are adapted in such a way that precise guidance is ensured, while at the same time sealing air can flow between the piston rod and the piston rod housing towards the openings.

[0039] Additionally or alternatively, it is also possible that the piston rod and / or inner surface of the piston rod housing has recesses running longitudinally along the piston rod, like tires, for guiding sealing air.

[0040] According to the invention, a method for assembling a centering device is further provided, comprising a piston rod with a piston rod housing receiving it, openings in the piston rod housing through which centering elements such as centering pistons are penetrated, each of which is connected to the piston rod via a positive-locking, dovetail-shaped connection for adjusting the centering elements, wherein a pin element extends from each centering element and engages in an associated groove of the piston rod or vice versa, wherein either each centering element has first contact surfaces for the planar bearing of the adjacent centering elements, wherein, for the insertion of the pins into the grooves, the centering pistons lie against each other via their first contact surfaces, and after insertion of the pin elements into the grooves, the piston rod is adjusted such that the outer surfaces of the fixing elements are flush or substantially flush or, if applicable,The centering pins are set back slightly from the circumferential surface of the piston rod housing, and adjustment of the piston rod is then prevented in such a way that the centering pins are radially adjustable inwards, or sections of the centering elements with their inner end faces bear against a removable assembly aid extending along the longitudinal axis of the piston rod housing, and then, after the pin elements are inserted into the grooves, the piston rod is adjusted so that the outer faces of the fixing elements are flush or substantially flush or, if necessary, set back from the circumferential surface of the piston rod housing, and adjustment of the piston rod is then prevented in such a way that the centering pins are radially adjustable inwards. It is particularly provided that the piston rod housing is open at the end face during assembly and that the opening is closed with the closing element, such as a cover, after assembly.

[0041] Further details, advantages and features of the invention will become apparent not only from the claims and the features to be derived therefrom - individually and / or in combination - but also from the following description of a preferred embodiment.

[0042] They show:

[0043] Fig. 1 shows a view of a first embodiment of a centering device,

[0044] Fig. 2 shows a section along line AA in Fig. 1,

[0045] Fig. 3 shows a view of a piston rod,

[0046] Fig. 4 shows a section along line AA in Fig. 3,

[0047] Fig. 5 shows another view of the piston rod according to Fig. 3,

[0048] Fig. 6 shows a section along line BB in Fig. 5,

[0049] Fig. 7 shows a sectional view of another embodiment of a piston rod,

[0050] Fig. 8 shows a centering piston,

[0051] Fig. 9 shows a section along line AA in Fig. 8,

[0052] Fig. 10 shows a top view of the centering piston during assembly of the

[0053] Centering device in schematic representation, Fig. 11 a section of a second embodiment of a centering device in perspective and partially cut away,

[0054] Fig. 12 shows a further detail of the second embodiment of the

[0055] Centering device according to Fig. 11,

[0056] Fig. 13 shows a section of the piston rod housing with piston rod and

[0057] centering element and

[0058] Fig. 14 shows a perforated disc.

[0059] The figures are intended to explain in more detail the centering devices according to the invention, with which components with receiving bores are centered.

[0060] Corresponding centering devices enable the force-fit centering of workpieces. The centering device according to the invention is particularly characterized by the fact that it can be dimensionally smaller, thus being suitable for workpieces with small-diameter receiving bores. Diameters of less than 25 mm, and in particular less than 15 mm, are examples.

[0061] To enable centering, neither clamping balls nor wedge elements are used. Instead, centering elements are employed that are positively connected to a piston rod, so that the centering elements can perform their function depending on the position of the piston rod.

[0062] The centering device 10 shown in Figures 1-10 has, regardless of the embodiment, a piston rod 12 which is axially adjustable in a piston rod housing 14. The piston rod housing 14 can be closed by a cover 16, which is removed during assembly.

[0063] The piston rod 12 is connected to a piston 18, which is adjustable within a housing 20, such as a device housing, that is installed in a machine or device in which a workpiece is to be machined. These housings are, for example, cast parts made of aluminum, steel, or gray cast iron, or plastic parts that have corresponding mounting bores into which the piston rod housing 14 can be inserted.

[0064] The piston rod housing 14 has a flange-like extension 22 in the proximal area, which is installed in the housing 20.

[0065] To perform centering, the centering device 10 has, in particular, centering elements having a cylindrical shape, one of which is shown in Figs. 8 and 9 and is marked with reference numeral 24.

[0066] In particular, three corresponding centering elements 24, hereinafter referred to as centering or clamping pistons, are provided, which penetrate corresponding openings in the piston rod housing 14, directly below the closing element 16, which closes the piston rod housing distally. One of these openings or bores can be seen in Fig. 1 and is marked with reference numeral 28. The corresponding bores are equidistant around the circumference of the piston rod housing 14.

[0067] The longitudinal axes of the openings 28 should run perpendicular to the longitudinal axis 36 of the piston rod 12 and thus of the piston rod housing 14.

[0068] The holes 28 serve as guides for the centering pistons 24 such that when the piston rod 12 is axially adjusted, the centering pistons 24 are pushed out of the housing 14 perpendicular to it or retracted circumferentially so that they are aligned with the circumferential surface 30 of the piston rod housing 14 or are offset from it.

[0069] The outer end faces of the centering elements, referred to simply as centering pistons 24, can also have the shape of a spherical segment. In this case, the radially outermost point of the centering pistons 24 should, in the retracted position, lie on the outer surface of the piston rod 12 or, if necessary, be slightly offset from the outer surface. Slightly offset inwards preferably means a maximum of 1 / 10 to 2 / 10 mm radially inwards only from the outer surface of the piston rod housing. To allow adjustment of the centering pistons 24, the piston rod 12 and the centering pistons 24 are positively connected to each other via a dovetail joint. This joint consists of pins 33 extending from the respective centering piston 24 and a groove 38 running in the proximal region 34 of the piston rod 12, inclined to the longitudinal axis 36 of the piston rod.

[0070] The grooves to the longitudinal axis 36 of the piston rod 12 can, for example, enclose an angle α between 20° and 45° without thereby restricting the teaching according to the invention.

[0071] Corresponding to the number of centering pistons, the grooves 38, 40, 42 are also equidistant from each other in the distal area 26, as can be seen from the sectional view according to Fig. 6.

[0072] As Figures 6 and 9 illustrate in particular, the pins 33 have a trapezoidal geometry in section, with the shorter base extending from the base body 32 of the centering piston 24. The length of the side legs 33, 37 is adapted in the longitudinal direction of the pins 24 to the course of the grooves 38, 40, 42 such that the pins 33 can be adjusted to the required extent. This is also evident from the side view in Figure 8.

[0073] The grooves 38, 40, 42 have side legs 41, 43 which are inclined such that the side legs 35, 37 of the pin 33 are guided along them. The bottom surface 45 of each groove should be channel-shaped and preferably approximately V-shaped, so that when the pins 33 are moved in the grooves 38, 40, 42, the longer base side 39 of the pin 33 is spaced or substantially spaced from the bottom surface 45. This ensures secure movement of the pins 33 in the grooves 38, 40, 42. Simultaneously, low-friction sliding is possible.

[0074] If, according to the embodiment shown in Figures 1 to 5, the piston rod 12 is a solid body, it can also be designed as a hollow body, as illustrated in principle by the piston rod 112 in Figure 7. Regardless of this, the previously described grooves 38, 40, 42 are also found in the distal region 126, so that the pins 33 extending from the centering pistons 24 can engage in them, thus enabling movement in the holes 28.

[0075] From the illustrations in Figs. 8 and 9 it can further be seen that the centering pistons 24 can transition flush with the circumferential surface 30 of the piston rod housing 12, at least in their edges.

[0076] The outer end face of the centering piston can also have the shape of a spherical segment. In this case, the outermost point of the end face, viewed in the longitudinal direction of the centering piston, should, in the retracted state, lie on the circumferential surface, i.e., the outer surface of the piston rod housing, or be set back from it.

[0077] The piston rod 12, 112 is screwed into the piston 18, as can be seen from the drawings.

[0078] The piston 18 has an upper section 44 and a lower section 46 of larger diameter, the lower section 48 acting as the piston, providing an annular piston surface 46 for adjusting the piston 18 and thus the piston rod 12. The hydraulic fluid inlet is indicated by reference numeral 49.

[0079] The proximal surface of piston 18 is also supplied with hydraulic fluid.

[0080] Furthermore, a sealing air connection 52 is provided, which flows between the piston rod 12 and the inner surface 54 of the piston rod housing 14 to the openings 28. For this purpose, the fit between the piston rod 12 and the piston rod housing 14 can be bored out in the proximal area, i.e., in the area furthest from the openings 28.

[0081] Alternatively or additionally, longitudinal grooves, such as ridges, may also be present in the inner surface 54 of the piston rod housing 14 and / or in the outer surface of the piston rod 12. Depending on the diameter of the piston rod housing 14, the wall thickness can range from 1.5 mm to 9 mm, in particular from 1.85 mm to 6.0 mm.

[0082] The diameter DG of the piston rod housing 14 can be between 9 mm and 25 mm.

[0083] The length of the piston rod housing 14 between cover 16 and flange 22 can be from 10 mm to 65 mm.

[0084] The length of the piston rod 12 between the proximal area of ​​the piston 18 and the tip of the piston rod can be between 50 mm and 140 mm.

[0085] To enable trouble-free assembly of the centering device 10 despite its small dimensions, the centering pistons 24 have contact surfaces 56, 58 that form an angle of 120° when three centering pistons 24 are arranged equidistantly around the circumference of the piston rod 12, as illustrated in the schematic diagram of Fig. 10. For assembly, the contact surfaces designated as the first contact surfaces lie against each other, as also shown in Fig. 10. This alignment is performed with the cover 16 removed.

[0086] Since the pins 33 have a unique assignment to the course of the contact surfaces 56, 58 and these have a unique geometric assignment to the grooves 38, 40, 42, the piston rod 12, 112 can be moved in the longitudinal direction such that the pins 33 penetrate into the grooves 38, 40, 42, whereby when the piston rod 12 is adjusted in the distal direction, the centering pistons 24 are moved apart.

[0087] After the centering pistons 24 and thus the piston rods 12, 112 have been assembled, the piston 18 is adjusted so that the outer surfaces of the centering pistons 24 should be flush with the surface 30 of the piston rod housing 14, at least in the outer area. In this position, the piston 18 is located above a groove 60 of the device or hydraulic housing 20, so that a snap ring 62 or another suitable element is then inserted into the groove 60, which serves as a stop for the piston movement. Thus, when using the centering device 10, it is ensured that in the initial position the centering pistons 24 always assume a desired position of their outer end faces, in particular that they are flush with the circumferential surface 30 of the piston rod housing 14. As the piston 18 moves further towards the distal end of the piston rod housing 14, the centering pistons 24 are correspondingly pushed outwards.

[0088] As an alternative to the design of the stop in the form of a snap ring, a step can be formed in the inner wall of the housing, against which, when the piston rod 12, 112 is in engagement with the centering pistons 24, a kind of perforated disc 70 is placed and secured, which acts as the stop to prevent the piston rod 12, 112 from being pulled back in such a way that the piston rod could come into engagement with the centering pistons 24.

[0089] A schematic representation of the perforated disc 70 can be seen in Fig. 14, which is, for example, glued into the housing 20.

[0090] In order for hydraulic fluid to flow through the perforated disc 70, it has through-holes, two of which are marked by reference numerals 72 and 74 as examples.

[0091] After the piston rod 12, 112 is positively connected to the centering pistons 24 in the manner described above, the piston rod housing 14 is closed by means of the cover 16.

[0092] Figures 11 and 12 show a second embodiment of a centering device 100, which differs from those of Figures 1 to 10 in that only two centering elements 124, 224 are used for centering, which are adjustable along a common straight line to the piston rod housing 114, the straight line intersecting the longitudinal axis of the piston rod housing 114.

[0093] The course of the bores for the centering elements 124, 224 to the closing element, such as a cover, which closes the piston rod housing 114, corresponds to the embodiment of Figs. 1-10. The same applies to the design of a stop for limiting the stroke movement of the piston rod. As explained above, the centering elements 124, 224, which also have a cylindrical shape and can therefore be referred to as centering pistons, are positively connected to a piston rod 212 which is axially adjustable in the piston rod housing 114, with a dovetail connection also being preferred.

[0094] In this arrangement, as in the embodiment of Figs. 1 to 10, a trapezoidal pin 133, 233 extends from the inner end face of each centering piston 124, 224, which engages in grooves 238 inclined to the longitudinal axis of the piston rod 212.

[0095] Since the centering elements 124, 224 are guided in openings of the piston rod housing 114, axial adjustment of the piston rod 212 results in adjustment of the centering elements 124, 224 out of or into the piston rod housing 114.

[0096] To align the grooves 238 of the piston rod 212 with the pins 133, 233 and to easily insert the pins 133, 233 into the grooves 238, an assembly aid 250 is provided according to the invention, which has an inner section 252 having a cylindrical shape. The inner section 252 is bounded by a first outer section 254 and a second outer section 256.

[0097] In the outer end faces of the pins 133, 233 there are second contact surfaces 258, 260, the geometry of which corresponds to the circumferential geometry of the inner section 252, i.e. in the case of a cylindrical geometry of the inner section 252 a circular section geometry e .

[0098] The length of the inner section 252 is designed to correspond to the length of the second contact surfaces 258, 260 in the axial direction of the piston rod 212, which is determined by the end face of the pin 133, 233 running parallel to the longitudinal axis.

[0099] The lower outer section 256 is inclined to the longitudinal axis of the piston rod 212 and has an angle of inclination corresponding to the outer surfaces 262, 264 of the pins 133, 233, and thus to the angle of inclination of the groove 238 to the longitudinal axis of the piston rod 212. The upper outer section 254 of the assembly aid 250, visible in Fig. 12, transitions via a step into the inner section 252. Thus, when the second contact surfaces 258, 260 bear against the inner section 252 of the assembly aid 250, the centering elements or pistons 124, 224 can be positively positioned relative to the assembly aid 250.

[0100] As a result, the pins 133, 233 have a unique positioning, which means that the pins 133, 233 can be easily inserted into the grooves 238 of the piston rod 212 by axially adjusting the latter.

[0101] After removing the pins 133, 233 from the grooves 238, the assembly aid is removed and the piston rod housing 114 is closed on the voice side.

[0102] Further assembly can then be carried out in accordance with the explanations given above to ensure that the centering pistons 124, 224 are always in engagement with the grooves 238 and that their outer end faces assume a desired position relative to the circumferential or cylindrical surface of the piston rod housing 114 when the centering device is to be inserted into a bore of a workpiece.

[0103] Even in the embodiment shown in Figures 11 and 12, it is not necessary for the outer end face of the centering pistons 124, 224 to be designed in such a way as to allow a flush transition into the circumferential surface of the piston rod housing 114. Instead, the outer surfaces can also be segment-shaped, with the radially extending area of ​​the centering elements 124, 224 extending to the outer surface of the piston rod housing 114, or preferably slightly recessed from it, preferably by a maximum of 1 / 10 mm to 2 / 10 mm, for the purpose of inserting the piston rod housing 114 into a bore of a workpiece.

[0104] The centering device according to the invention is characterized by its small size, enabling the easy centering and clamping of workpieces with mounting bores smaller than 25 mm, and particularly smaller than 15 mm. Preferred dimensions are explained with reference to Fig. 13. The piston rod housing 14, 114 preferably has a diameter DG between 9 mm and 25 mm. The wall thickness Dwi of the piston rod housing 14, 114 should be between 1.85 mm and 5.8 mm in the area where the piston rod 1212 slides against the inner surface of the piston rod housing 14, 114.

[0105] In the distal region, the piston rod 12, 112, 212 has a reduced diameter. This results in a distance from the inner surface of the piston rod housing 14, 114, as can be seen in Fig. 13.

[0106] In the area where, with the piston rod 12, 112, 212 retracted, the grooves 38 for receiving the pins 33 of the centering pistons 24 begin, the wall thickness of the piston rod housing is again widened inwards such that the piston rod 12, 112, 212 can be guided slidably along the inner surface, thus ensuring secure guidance of the centering pistons 24 in the openings 28 in the housing wall of the piston rod housing 14, 114 perpendicular to the longitudinal axis of the piston rod housing 14, 114. In this area, the piston rod housing 14, 114 should have a wall thickness Dw2 between 2.05 mm and 6.0 mm. The wall of the piston rod housing 14 therefore has an inwardly offset section 15 in this area.

[0107] In order to enable safe centering and clamping even for shallow bores in accordance with the teachings of the invention, the openings 28 run directly in the area of ​​the cover 16, so that the centering pistons 24 are radially adjustable directly at the distal end area of ​​the piston rod housing 14, 114.

[0108] The distance Ai between the apexes of the holes 28 on the cover side and the end face of the piston rod housing 14 should be between 2.25 mm and 5.00 mm, preferably between 2.25 mm and 3.5 mm.

[0109] The closure element, the cover 16, should have a thickness Do in the range of 1.5 mm to 3.00 mm, preferably between 1.5 mm and 2 mm. The distance A2 between the inside of the cover 16 and the distal apex 29 of the opening 28 should be between 0.65 mm and 2.0 mm, preferably between 0.65 mm and 1.5 mm. In particular, the outer surface of the cover 16 and the end face of the piston rod housing 14, 114 should lie in a common plane extending perpendicular to the longitudinal axis of the piston rod housing 14, 114.

[0110] In the preceding explanations of the exemplary embodiments of the pins of the positive-locking connection, the starting point is the centering elements such as pistons, and the

[0111] If the piston rod opens the grooves to adjust the centering elements guided in the openings of the piston rod housing, pins could extend from the piston rod housing that engage in grooves of the centering elements. In this respect, interchangeability is provided, which is covered by the invention.

Claims

Patent claims Centering device and method for assembling such a 1. Centering device (10, 100), in particular designed for centering a workpiece, comprising a piston rod (12, 112, 212) adjustable in a piston rod housing (14, 114), which is connected in the proximal region to a piston (18) adjustable in a housing (20), and centering elements (24, 124, 224) interacting with the piston rod for adjusting it, wherein the piston rod housing (14, 114) has openings (28) in its distal region for guiding the centering elements (24, 124, 224) which engage positively with the piston rod such that, when the piston rod is axially adjusted, the fixing elements guided in the openings are peripherally engaged over the circumferential surface (30) of the piston rod housing (14, 114).114) projecting or extending peripherally or substantially peripherally to the circumferential surface or the radially outermost region of the respective centering element lies on the cylindrical surface spanned by the piston rod housing or is set back from it, characterized in that the piston rod housing (14, 114) is closed distally by a removable closing element (16), and that the openings (28) are provided in the piston rod housing adjacent to the closing element.

2. Centering device according to claim 1, characterized in that the centering elements (24, 124, 224) are connected to the piston rod (12, 112) via a dovetail-shaped connection (32, 38, 40, 42).

3. Centering device according to claim 1 or 2, characterized in that a pin element (33, 133, 233) extends from the centering element (24, 124, 224) and engages in a groove (38, 40, 42, 238) inclined to the longitudinal axis (36) of the piston rod (12, 112, 212) or vice versa, wherein adjusting the piston rod (12, 112, 212) preferably causes the centering elements (24, 124, 224) to be adjusted perpendicular to the longitudinal axis (36) of the piston rod, wherein in particular the bottom surface 45 of the grooves is designed in a channel shape.

4. Centering device according to at least one of the preceding claims, characterized in that the centering element (24, 124, 224) is a centering piston having a cylindrical geometry, from the inner end face of which the pin (33, 133, 233) extends and whose outer end face is either at least partially geometrically adapted to the contour of the circumferential surface (30) of the piston rod housing (14, 114) or has a spherical segment geometry.

5. Centering device according to at least one of the preceding claims, characterized in that the centering piston (24, 124, 224) has a diameter Ds of 3.5 mm < Ds < 7 mm and / or the piston rod (12, 112, 212) has a diameter DK of 6 mm < DK < 15 mm and / or the piston rod housing (14, 114) has a diameter DG of 9 mm < DG < 25 mm and / or a distance Ai between the distal apex (29) of the opening (28) and the end face of the piston rod housing (14, 114) of 2.25 mm < Ai < 5.00 mm.

6. Centering device according to at least one of the preceding claims, characterized in that the centering device (10) has at least three centering elements such as pistons (24) which pass through the openings (28) extending at equidistant intervals of the piston rod housing (14).

7. Centering device according to at least one of the preceding claims, characterized in that the inner end face of each centering element such as piston (24) has two contact surfaces (56, 58) which enclose an angle such that the contact surfaces (56) of one of the centering elements such as piston (24) abut each a contact surface of the adjacent centering element such as piston.

8. Centering device according to at least one of claims 1 to 5, characterized in that the centering device (100) has two centering elements (124, 224) which are adjustable along a longitudinal axis intersecting the piston rod (212), that the inner end face of each centering element or piston has a second contact surface (258, 260) which is adapted to a bearing surface of an assembly aid (250) which is displaceable along the longitudinal axis of the piston rod (212), and that when the second contact surfaces bear against the opposite surface during axial adjustment of the piston rod, the grooves can be brought into engagement with the pin elements arranged in alignment with them.

9. Centering device according to at least claim 8, characterized in that the assembly aid (250) in the contact area with the second contact surfaces (258, 260) has a cylindrical geometry and the second contact surfaces in section have a circular segment geometry, wherein preferably the second contact surfaces are outer sides of the pin elements (133, 233) of the centering elements such as pistons (124, 224).

10. Centering device according to at least one of the preceding claims, characterized in that the piston rod (12, 112, 212) extends from a piston (18) which is adjustable in a housing (20) which can be installed with a device or machine for machining the workpiece centered and clamped by the centering device (10, 100).

11. Centering device according to at least one of the preceding claims, characterized in that the housing (20) has a removable stop (62) such that, in a first position of the piston (18) and with the centering elements such as pistons (24) lying flat against each other over the first contact surfaces (56, 58) or with the second contact surfaces (258, 260) bearing against the assembly aid (250), the grooves (38, 40, 42, 238) can be inserted into the pin elements (33, 133, 233) of the centering elements (24) and that, with the centering elements transitioning flush into the circumferential surface (30) of the piston rod housing (14, 114) or with the end faces of the centering elements extending back from the circumferential surface, the piston assumes a second position which is secured by the stop (62) in such a way that movement of the piston in the direction of the first Position excluded.

12. Centering device according to at least one of the preceding claims, characterized in that the fit between the piston rod (12, 112, 212) and the piston rod housing (14, 114) is enlarged in its proximal region to guide sealing air and / or that the piston rod (12, 112, 212) and / or inner surface (54) of the piston rod (12, 112, 212) has recesses extending in the longitudinal direction of the piston rod for guiding sealing air.

13. Method for assembling a centering device (10, 100) comprising a piston rod (12, 112, 212) with a piston rod housing (14, 114) receiving it, openings (28) in the piston rod housing which are penetrated by centering elements, such as centering pistons (24, 124, 224), each of which has a A positive-locking, dovetail-shaped connection is made to the piston rod for adjusting the centering elements, wherein a pin element (33, 133, 233) extends from each centering element and engages in an associated groove (38, 40, 42, 238) of the piston rod, or vice versa, wherein either each centering element has first contact surfaces (56, 58) for the planar contact of the adjacent centering elements, wherein the centering pistons lie against each other over their first contact surfaces to insert the pins into the grooves, and after the pin elements are inserted into the grooves, the piston rod is adjusted such that the outer end faces of the fixing elements are flush or substantially flush or recessed with the circumferential surface (30) of the piston rod housing, and then adjustment of the piston rod is prevented such that the centering pins are radially adjustable inwards, or wherein sections of the centering elements (124,224) with their inner end faces a removable mounting aid (250) extending along the longitudinal axis of the piston rod housing, and then, after the pin elements are inserted into the grooves, the piston rod is adjusted such that the outer faces of the fixing elements are flush or substantially flush or recessed with the circumferential surface (30) of the piston rod housing, and then adjustment of the piston rod is prevented such that the centering pins are radially adjustable inwards.

14. Method according to claim 13, characterized in that during assembly the piston rod housing (12, 112, 212) which can be closed distally with a closing element (16) is open and after assembly the opening is closed.

15. Method according to claim 12 or claim 13 using a centering device according to at least one of claims 1 to 11.

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