EP4221968B1 - Radial press - Google Patents

Description

The present invention relates to a radial press, i.e. a press which serves to radially deform a workpiece with respect to a press axis while reducing its radial dimensions.

Typical workpieces subjected to radial forming using such a radial press are the connection fittings attached to the end of a hydraulic hose line. In these cases, a sleeve surrounding the hose is pressed radially inwards towards a "nipple" inserted into the hose, so that the hose is clamped between the nipple and sleeve and is thus secured against being pulled out of the fitting. Other typical assemblies with components joined using radial pressing are anchor elements, high-voltage insulators, etc. Other practical applications of radial presses of the type in question here relate to workpiece radial forming, which takes place outside of joining processes.

Radial presses suitable for radial pressing of the type described above are known in various designs and various configurations. Reference should be made, for example, to the EN 20 2016 100 660 U1 , EN 20 2016 008 097 U1 , EN 10 2016 106 650 A1 , EN 10 2014 014 585 B3 , EN 10 2014 012 485 B3 , EN 10 2014 008 613 A1 , EN 10 2011 015 770 A1 , EN 10 2011 015 654 A1 , EN 10 2009 057 726 A1 , EN 10 2005 041 487 A1 , EN 10 2005 034 260 B3 , DE 601 21 915 T2 , DE 298 24 688 U1 , DE 199 44 141 C1 , DE 199 40 744 B4 , DE 101 49 924 A1 , DE 41 35 465 A1 and EN 35 13 129 A1 . Regardless of their respective design and other technical features, the known radial presses have in common that a plurality of pressing bodies with a roughly wedge-shaped cross-section, evenly distributed around the pressing axis - the most common are eight pressing bodies - are moved evenly (and typically simultaneously) radially in the direction of the pressing axis by means of a (typically hydraulic) drive. The pressing bodies have a pressing surface (e.g. concave, designed as a segment of a circular cylinder) radially on the inside, which is in contact with the workpiece during forming; the geometry of the pressing surface usually corresponds essentially to a segment (e.g. one eighth) of the target geometry of the workpiece after forming. In this respect, it should be noted that the radial presses in question here are suitable for the radial forming of workpieces with a wide variety of geometries, ranging from (idealized) circular-cylindrical workpieces to other strictly rotationally symmetrical workpieces (i.e. workpieces with circular cross-sections of different radii - perpendicular to a workpiece axis) to workpieces with non-circular, e.g. polygonal cross-sections.

A pressing device for radial pressing of press fittings onto pipe ends, working according to a different technical concept, is the DE 295 00 338 U1 It comprises a split press ring that can be closed around the press fitting with distributed around the inner circumference, radially inwardly movable by means of a feed device, as rotating press rollers. A similar functional and construction principle is used for the press device according to the DE 200 23 234 U1 According to the EP 0 916 426 B1 This concept is implemented for forming an end part of an otherwise cylindrical workpiece, such as a metal housing, wherein the end part is eccentric and reduced in diameter with respect to the cylindrical region of the workpiece.

The known radial presses of the applicant, designed in accordance with the state of the art described above (see also www.uniflex.de), have certainly proven themselves in practice. They can be used to produce reliable and reproducible radial pressings that meet even the highest requirements. However, for certain application situations, radial presses would be desirable that can solve similar forming tasks as conventional radial presses based on the state of the art, albeit with a less powerful drive unit. One of the reasons for this is the need for radial pressings to be carried out in clean air rooms. Radial presses with purely electric press drives are more suitable for this than those with electro-hydraulic press drives, although purely electric drives do not come close to the high power density of electro-hydraulic drives.

The above object is achieved according to the present invention by the radial press specified in claim 1. The radial press according to the invention is accordingly characterized in that it has a base, a hollow ring die rotatably mounted thereon with respect to a pressing axis, with an inner contour tapering in the direction of the pressing axis and rotationally symmetrical to the pressing axis, and a rolling element unit rotatable with respect to the pressing axis, with a pressure ring surrounding the pressing axis and a plurality of rolling elements arranged around the pressing axis, rotationally symmetrical and tapering at least in regions, which are rotatably axially supported on the pressure ring at a variable distance from the pressing axis and can roll on the inner contour of the ring die, wherein a rotary drive which causes the rotation about the pressing axis acts on the ring die and/or the rolling element unit, and wherein a feed drive which causes the axial adjustment of the rolling element unit and the ring die relative to one another along the pressing axis also acts on the rolling element unit and/or the ring die. The feeding of the rolling elements in the sense of a reduction of the pressing dimension - this is understood to mean the workpiece radial dimension resulting from the radial forming, in particular the workpiece diameter - is carried out by an axial adjustment of the rolling element unit relative to the ring die by means of the feed drive.

In this way, the present invention completely breaks away from the concept pursued by all established radial presses, which is characterized (see above) by radially moving press bodies, which during the radial forming continuously rest on the workpiece with a (typically concave) pressing surface; between the press body and the workpiece there is typically a relatively stationary Contact. Instead, according to the invention, the radial forming takes place via rolling elements which roll on the surface of the workpiece and on the inner contour of a ring die, whereby the radial feed of the rolling elements - for progressive reduction of the pressing dimension - takes place by an axial displacement of the rolling element unit relative to the ring die, the inner contour of which tapers along the pressing axis. Instead of resting on the workpiece to be formed over a comparatively large area, as conventional pressing elements with their concave pressing surfaces do, in the radial press according to the invention the rolling elements which cause the forming of the workpiece and which taper at least in some areas - the orientation of the tapering of the rolling elements is the same as that of the tapering of the inner contour of the ring die in relation to the pressing axis - are in contact with the workpiece only over comparatively small areas, typically close to a line contact. The geometry of the contact surfaces can be influenced in particular by the geometry of the rolling elements, as will be shown in more detail below, so that rectangular but also trapezoidal contact surfaces can be created. Unlike with conventional radial presses (see above), the contact surfaces of the rolling elements "wander" on the surface of the workpiece; in implementing the invention, therefore, radial pressing does not take place in a discrete number of levels (e.g. four levels with 8-jaw radial presses), but rather a circumferential radial deformation. In this way, the pressing required for deformation of the workpiece can be provided with significantly lower acting forces than in the case of established radial presses. This in turn allows the use of substantially less powerful radial press drives to complete specified radial press tasks than in the case of conventional radial presses. For example, as a result of this, various typical radial press forming processes can be carried out with radial presses according to the invention, in which the rotary drive causing the rotation of the ring die and/or the rolling element unit around the press axis and the feed drive causing the axial adjustment of the rolling element unit and the ring die relative to each other along the press axis are designed as comparatively compact, purely electric drives. At least with such direct use of electric drives, improved efficiencies and very good energy efficiency can be achieved as a result of the elimination of the energy conversion from mechanical to hydraulic energy and thus the associated conversion losses.

A significant further advantage of the present invention can, in individual cases, be the possibility of radially forming workpieces in such a way that they are ideally strictly rotationally symmetrical at the end of the radial forming process, in that they have - in the case of an ideal circular-cylindrical geometry - an ideally circular cross-section (or - in the case of another strictly rotationally symmetrical geometry - different ideally circular cross-sections). This is generally not possible with conventional radial presses because, during the pressing process, webs are formed between two adjacent pressing bodies - due to material being displaced outwards - under which even more or less pronounced "tunnels" can form. Such a In extreme cases, non-uniformity can even encourage the formation of cracks or the occurrence of other damage. In this respect, too, the radial press according to the invention can prove to be superior to the state of the art.

It should be noted that when using radial presses according to the invention, the radial deformation of the workpiece can also be limited to individual areas of the workpiece surface that are spaced apart from one another in the circumferential direction. In this case, the rolling elements do not roll over the entire circumference of the workpiece, but only over partial areas - possibly oscillating. The radial press according to the invention can therefore be used specifically to produce non-circular workpieces. The same applies if the rolling elements' feed increases and decreases rhythmically during their rotation as a result of a corresponding rhythmic relative axial movement between the ring die and the rolling element unit.

The statement that the rolling elements taper at least in some areas expresses that a tapered geometry of the rolling elements does not necessarily have to extend over their entire axial length. Rather, it is also conceivable, for example, that the rolling elements are cylindrical over part of their axial length or even widen, as is the case for rolling elements with a (symmetrical or asymmetrical) spherical or barrel-shaped geometry. The decisive factor is that the rolling elements are in rolling contact with the inner contour of the ring die, which tapers in the same direction, in that tapered area. Furthermore, it is clear from the above that The inner contour of the ring die in the context of the present invention does not have to taper over its entire axial extent; rather, a taper over part of the axial length is sufficient, with this tapered area being available for the rolling contact of the rolling elements. Thus, the statement in the claim that the ring die has an inner contour that tapers in the direction of the pressing axis and is rotationally symmetrical to the pressing axis is to be understood as meaning that the ring die is designed in this way at least in some areas.

As a precautionary measure, and to avoid misconceptions, it should be pointed out that the statement that the rolling elements "roll" on the inner contour of the ring die should not be interpreted - in the sense of perfect rolling - to mean that in the area of contact between the respective rolling element and the inner contour of the ring die there is no relative movement of the surfaces of the rolling element and the ring die to one another. Rather, such a relative movement (in the circumferential direction) is certainly possible, at least locally limited (see below). Furthermore, and also to avoid misconceptions, it should be pointed out that a rotary drive acting on the rolling element unit and causing it to rotate around the press axis - alternatively or in addition to a rotary drive of the pressure ring - can also be designed in the form of a drive that primarily sets the individual rolling elements (or at least some of them) in rotation, with the rolling elements rolling on the workpiece as a result of the rotation imposed on them. If the workpiece, as is the case for various typical radial press applications, If the radial press is held in a rotationally fixed manner, the pressure ring of the rolling element unit and the ring die are set in rotation relative to the press axis by the rolling elements rolling on the workpiece and on the inner contour of the ring die. If, however, rotation of the workpiece is to be considered, the pressure ring of the rolling element unit or the ring die can be rotationally fixed, depending on the individual design of the radial press.

As a precaution, it should also be explicitly pointed out that using radial presses according to the invention, workpieces can also be produced in which local constrictions or comparable surface depressions are provided. For this purpose, the rolling elements can be designed to be correspondingly short and/or profiled in the direction of their axis or have a non-tapering geometry. A surface structuring of the workpiece can also be achieved by structuring the rolling elements accordingly; in this sense, the rolling elements can, for example, have small surface depressions, which result in corresponding surface elevations (e.g. knobs) forming on the workpiece.

According to a first preferred development of the invention, the rolling elements as well as the inner contour of the ring die have a substantially frustoconical basic shape, whereby the term "substantially" expresses the fact that a mathematically exact frustoconical geometry is not important. For example, approximate conical shapes, but with a slightly curved or indented Surface rolling elements are not only possible within the scope of this development, but in individual cases are even very advantageous. According to an exemplary advantageous embodiment of such a "substantially truncated cone-shaped basic shape" of the rolling element, its "cone angle" changes continuously over its extension along its own axis. Particularly preferably, the double cone angle of the rolling elements - which have a substantially truncated cone-shaped basic shape - corresponds essentially to half the cone angle of the ring die. Such a configuration of the radial press is particularly predestined for pressing workpieces with a completely or at least approximately circular cylindrical surface, whereby the dimensions of the radial press can be comparatively small. Rolling elements with a truncated cone basic shape are also those rolling elements that are strictly truncated cone-shaped over a large part of their extension, but deviate from this in subordinate areas (e.g. adjacent to one end or both ends), for example rounded, cylindrical, chamfered, or the like. The same applies if the rolling elements are not profiled at the end in a way that deviates from a truncated cone, but rather at any position between the ends; in this sense, the rolling elements can, for example, have (at least) one circumferential groove, whereby (at least) one corresponding circumferential rib is formed on the workpiece during radial deformation. Within the framework of the essentially truncated cone-shaped basic shape of the rolling elements and the inner contour of the ring die, various different details are therefore possible. Designs are possible which prove advantageous for different application situations of the radial press.

According to a first particularly preferred embodiment, the inner contour of the ring die and the rolling elements can be geometrically designed to be exactly truncated cone-shaped. This results in a precise and clearly defined position of the rolling elements, resulting in a particularly high reproducibility of the forming process. However, a surface relative movement of the rolling elements to the workpiece and the ring die - more or less pronounced depending on the individual geometric conditions - is unavoidable; a pure rolling movement of the rolling elements on the surface of the workpiece and on the inner surface of the ring die cannot be achieved.

In order to reduce the "scratching" in question and the associated adverse effects, the rolling elements can - according to another particularly preferred embodiment - be slightly crowned, with a possibly geometrically exact frustoconical design of the inner contour of the ring die. In this way, the contact pressure of the rolling elements on the workpiece and ring die is not homogeneous over their axial extension; rather, it has a maximum more or less halfway along the length of the rolling elements and decreases towards both of their front sides. This proves to be particularly advantageous in constellations in which the workpiece is axially (possibly several times back and forth) relative to the rolling elements during the forming process - with a successively decreasing press diameter. is moved so that the area of the current forming on the workpiece "wanders" (back and forth if necessary) in order to gradually cover the entire forming area of the workpiece. A slightly crowned design of the rolling elements can accommodate the axial relative movement of the rolling elements and the workpiece to one another. But even in constellations in which the rolling elements cover the entire forming area of the workpiece without such axial movement of the workpiece and rolling element unit relative to one another, a slightly crowned design of the rolling elements can be advantageous, namely in order to create a stress distribution in the workpiece, with stresses decreasing towards the edges of the forming area, which can have a positive effect on the service life of the workpiece. The possibility of influencing the shape of the contact surface between the rolling elements and the workpiece via the geometry of the rolling elements - in relation to the geometry of the workpiece to be formed - can also be used to create an essentially rectangular contact surface in order to avoid local load peaks.

The aforementioned "erasure" or possible adverse effects thereof can, according to yet another particularly preferred embodiment, also be reduced by - with a possibly geometrically exact frustoconical design of the rolling elements - the inner surface of the ring die being slightly curved, i.e. slightly drawn inwards towards the axis compared to an exact conical surface. This also results in an inhomogeneous distribution of the contact pressure of the rolling elements (over their axial extent) on the ring die. The axial adjustment The movement of the rolling element unit relative to the ring die for the purpose of feeding the rolling elements in the radial direction is expressed in this case in a more or less pronounced change in the angle of attack of the rolling element axes to the pressing axis - depending on the degree of curvature of the inner surface of the ring die - and thus in a change in the geometry of the forming area defined by the entirety of the rolling elements (e.g. by a transition from slightly conical to circular cylindrical). This can be used to specifically influence the course of the radial pressing, for example by deliberately gradually shifting the current area of the workpiece forming during a complete radial pressing.

As far as the ring die is concerned, this can be made in one piece. A particularly preferred embodiment of the invention is characterized by a multi-part design of the ring die in such a way that it comprises a support ring and an insert that is exchangeably received in this and defines the inner contour. With such a design, several particularly practical advantages can be achieved. In the event of wear (cf. the possible "erasing" of the rolling elements discussed above), the radial press can be restored or reconditioned with minimal use of material and time. This advantage can be achieved by using a replaceable, e.g. more or less funnel-shaped, deep-drawn plain bearing plate, in which case the inner surface of the ring die can be designed with grooves, holes or the like (see below) particularly easily.

In addition, with a suitable multi-part design of the ring die, the radial press can be adapted to different pressing tasks (e.g. different starting and/or final diameters of the workpiece) with very little effort by replacing one insert with another with a different internal geometry, so that the full radial feed of the rolling elements - provided by the axial displacement of the ring die and rolling element unit relative to each other - is available for the effective radial forming of the workpiece.

A device that may be provided to hold the workpiece during radial pressing is conveniently mounted on the base of the radial press. If the rolling elements on the workpiece have to move axially (possibly multiple times) during radial pressing (see above), this holding device allows the held workpiece to be axially displaced relative to the base to a predetermined extent, for which purpose two (possibly adjustable) stops are conveniently provided.

According to another preferred development of the invention, the rolling elements are rotatably mounted on bearing pieces which are guided on the pressure ring - preferably in undercut guides of the pressure ring - so that they cannot be lifted out - on sliding surfaces. Particularly preferably, the said sliding surfaces are designed on the surface of exchangeable plain bearing plates. This allows a uniform low-friction feeding of the rolling elements can be ensured, which is reflected in optimal operating behavior of the radial press in terms of high quality of radial pressing with good reproducibility of the radial forming. The sliding surfaces - these can be flat or more or less curved - can extend perpendicular to the press axis. However, it is particularly advantageous if the sliding surfaces are inclined to the press axis, in the opposite direction to the taper of the inner contour of the ring die, although ideally significantly steeper than the latter. For example, with a half cone angle of the essentially frustoconical inner contour of the ring die of between 10° and 20°, the angle of attack of the sliding surfaces with respect to the press axis can be between 80° and 85°. As part of an embodiment of the invention with a particularly low-friction feeding of the rolling elements, hydrodynamic bearings of the bearing pieces on the pressure ring can also be used. Such a "wet" storage of the bearing pieces on a pressure fluid cushion is particularly suitable when a "wet" radial deformation of the workpiece is also carried out, ie a radial compression that takes place while the deformation zone is exposed to (lubricating and/or cooling) fluid.

Especially with regard to such forces which can act on the rolling elements in the circumferential direction (as a result of the local etching of the surfaces of the rolling elements on the inner contour of the ring die explained above), it proves to be advantageous if - according to another preferred development of the invention - the pressure ring is part of a rolling element cage which has a wall with openings in which the rolling elements are pivotally mounted on both of their front sides. For the purpose of advancing the rolling elements, both front-side pivot bearings of each rolling element each comprise a bearing piece which is slidably guided on a sliding surface in an associated guide of the rolling element cage.

Yet another preferred development of the invention is characterized in that the base is designed like a housing, with a casing section of the base at least partially surrounding the ring die. The housing-like base also offers protection for the rotating parts of the radial press, while minimizing the risk of injury for the operator. Ideally, the housing-like base is closed to such an extent or so completely (if necessary by means of a cover or the like) that all rotating parts are completely enclosed or at least covered. Parts of the radial press that protrude from the housing-like base (such as in particular components of the feed drive) are ideally non-rotatable/non-rotatable. According to a preferred embodiment, the feed drive can comprise a pressure tube that is coaxial with the press axis, which acts on the pressure ring via an axial bearing and is guided on the base so that it can be moved along the press axis via a non-rotatable linear guide. The workpiece can be introduced through the pressure tube into the processing space between the rolling elements if necessary. An alternative or additional accessibility of the processing space for loading it with a workpiece consists, according to a preferred development of the invention, in that the base has an opening extending around the press axis adjacent to the front side of the ring die associated with the smaller diameter of the inner contour. In individual cases, feeding the machining area with a workpiece through such an opening is particularly advantageous even from the point of view of the quality of the formed product. Access to the machining area from both sides can be associated with particularly pronounced advantages if the radial press is part of an automated production line; because a workpiece flow with workpiece loading from one side and workpiece removal to the other side of the radial press is very advantageous from the point of view of process efficiency.

According to yet another preferred development of the invention, an odd number of rolling elements is provided so that no two rolling elements are diametrically opposed to each other. This proves to be very advantageous with regard to the quality of the radial compression; because in this way the risk of undefined operating and load conditions is significantly reduced. Against the same background, it is advantageous if the rolling element unit has preload springs which preload the rolling elements outwards to rest on the ring die. For typical applications, three, five or seven rolling elements prove to be very advantageous, with preferably five rolling elements being provided; and the average (outer) diameter of the rolling elements is preferably between 15% and 30%, particularly preferably between 20% and 25% of the mean (inner) diameter of the ring die.

For various application situations, it is advantageous if the surface of the rolling elements is more or less perfectly smooth, e.g. polished. However, this is by no means always the case. Rather, another preferred development of the invention is characterized by the fact that the surface of the rolling elements is profiled. For example, for the radial forming of workpieces made of certain materials, it can be advantageous if the rolling elements have a knob-like profile, which ensures a more or less localized concentration of the pressing forces, with the surface of the workpiece being leveled out by rolling over it several times. Other profiles can also have a positive effect in individual cases. For easier positioning of the rolling elements during the radial forming process, a helical profile of the rolling elements can prove advantageous. The axial counter-holding forces on the workpiece can also be reduced by targeted roughening of the rolling element surfaces. And a micro-toothing that extends in a ring-shaped manner over the respective circumference of the rolling element in question promotes the frictional connection between the rolling element and the ring die and in this way prevents the rolling elements from blocking (when a rotary drive acts on the ring die).

As far as the surface of the inner contour of the ring die is concerned, for various common applications an at least approximately ideally smooth (e.g. polished) Execution is favorable. However, different designs can also prove advantageous here. A particularly preferred development in this respect is characterized in that the inner contour of the ring die is grooved, in particular by having a - or at least one - helical groove. In this case, without affecting the smooth running of the rolling elements, abrasion, dirt, etc. can be removed from the running zone of the rolling elements along the groove, whereby the groove in question can also be connected to a suction system for this purpose. The removal of abrasion, dirt and the like not only increases the dimensional accuracy and other manufacturing quality of the workpieces; it also has a positive effect on the service life of the radial press. In the above respect, according to an alternative preferred embodiment of the invention, perforation of the inner contour of the ring die can also prove advantageous, whereby here too the holes in question are particularly preferably connected to a suction system. This can be implemented particularly effectively with a radial press, in which the ring die (as explained above) is made up of several parts with a support ring and an insert that is exchangeably housed in this and defines the inner contour. The latter can be "ventilated" through a suitable ring cavity between the support ring and the insert, and holes made in the insert are connected to the ring cavity in question to remove abrasion or dirt. Even the introduction of local depressions (comparable to dents) into the surface of the inner contour of the ring die can be advantageous. Dirt can accumulate there; it can be removed by regular cleaning.

Within the scope of the present invention, several variants are considered for the implementation of the rotary drive, which causes the rolling elements to roll on the - non-rotating - workpiece. From a structural point of view, it is particularly advantageous if the rotary drive acts exclusively on the ring die. In this case (comparable to the situation in a planetary gear) the rolling element unit is driven at a correspondingly reduced speed. However, it is also conceivable that the rotary drive acts exclusively on the rolling element unit (i.e. the pressure ring and/or the rolling elements), in which case (again comparable to the situation in a planetary gear) the ring die is driven at a correspondingly increased speed. It is also possible to have the rotary drive act on both the rolling element unit and the ring die. By influencing the direction of rotation and speed of the two components using an appropriate control, a possible rotation of the workpiece can also be influenced in this case. Although this is more of an exception in typical applications, it can still be advantageous in individual cases. If the rotary drive acts exclusively or at least also on the ring die, it is particularly advantageous from a static point of view and therefore from the point of view of manufacturing precision if the bearing of the ring die at the base comprises two spatially separated bearing units, with the point of application of the rotary drive on the ring die being between the two bearing units.

Several variants are also possible with regard to the implementation of the feed drive within the scope of the present invention. From a structural point of view, it is particularly advantageous if the feed drive acts exclusively on the rolling element unit, with the ring die being axially secured relative to the base. However, in individual cases, a reversal in that the feed drive acts exclusively on the ring die can also prove to be advantageous, in which case the rolling element unit is axially secured relative to the base. Finally, a design is also conceivable in which both the rolling element unit and the ring die are axially displaceable relative to the base, with the feed drive acting on both the rolling element unit and the ring die.

According to a modification of the invention explained above according to the features of claim 25, essentially cylindrical or at least partially widening rolling elements can be used instead of rolling elements that taper at least in some areas. A radial press designed in this way is suitable for the production of radially formed workpieces that are not to have a cylindrical but rather a conical geometry in the radial forming zone. This is explained in the description of the figures (see the explanations for the Figures 4 and 5 ) in more detail. The same applies to a further modification of the invention explained above according to the features of claim 26 in that the ring die is not rotating, but rather is rotationally fixed with respect to the base. For these two modifications of the invention Compared to the basic concept explained above, various of the preferred embodiments described in more detail in the subclaims prove to be advantageous.

• eine Basis,
• eine an dieser bezüglich einer Pressachse drehbar gelagerte hohle Ringmatrize mit einer sich in Richtung der Pressachse verjüngenden, nicht rotationssymmetrisch ausgeführten Innenkontur, welche eine Mehrzahl von gleichmäßig um die Pressachse herum angeordnete, zu der Pressachse geneigte taschenförmige Aufnahmen für Wälzkörper aufweist, und
• eine bezüglich der Pressachse drehbare Wälzkörpereinheit mit einem die Pressachse umgebenden Druckring und einer Mehrzahl von um die Pressachse herum angeordneten rotationssymmetrischen, ggf. sich zumindest bereichsweise verjüngend ausgeführten Wälzkörpern, welche jeweils an dem Druckring mit variablem Abstand zu der Pressachse drehbar axial abgestützt und um ihre eigene Achse drehbar und längs der Achse der zugehörigen taschenförmigen Aufnahme verschiebbar gleitend in letzterer gelagert sind,

wobei auf die Ringmatrize und/oder die Wälzkörpereinheit ein deren Rotation um die Pressachse bewirkender Drehantrieb einwirkt und wobei ferner auf die Wälzkörpereinheit und/oder die Ringmatrize ein die axiale Verstellung der Wälzkörpereinheit und der Ringmatrize relativ zueinander längs der Pressachse bewirkender Vorschubantrieb einwirkt.In an even more modified form, the concept underlying the invention in the scope explained above is modified with comparable advantages (cf. Fig.5 and claim 27) that the inner contour of the ring die - which in turn tapers in the direction of the pressing axis - is not rotationally symmetrical, but rather has a plurality of pocket-shaped receptacles for the rolling elements, which are arranged evenly around the pressing axis and are inclined to the pressing axis, whereby the rolling elements do not roll on the inner contour of the ring die, but rather are each rotatable about their own axis and are slidably mounted in the associated pocket-shaped receptacle along the axis of the latter. Here, a fluidic bearing proves to be advantageous. The pocket-shaped receptacles can in particular have a partially cylindrical surface, with a cylinder axis inclined to the pressing axis. The cylinder axes intersect one another at a common intersection point lying on the pressing axis. In this case, too, the rolling elements can be designed to taper at least in some areas. However, this is not mandatory. For example, they can also be designed cylindrically, which is particularly useful when the workpiece in the radial forming zone is not to have a cylindrical but rather a conical geometry. This modification of the invention also Compared to the basic concept explained above, various of the preferred embodiments described in more detail and specified in the subclaims prove to be advantageous. Formulated independently and positively (ie not as a modification of the definition of the invention according to claim 1), the relevant implementation of the invention explained above can be defined as a radial press, comprising

• a base,
• a hollow ring die rotatably mounted thereon with respect to a pressing axis, with an inner contour tapering in the direction of the pressing axis and not rotationally symmetrical, which has a plurality of pocket-shaped receptacles for rolling elements arranged evenly around the pressing axis and inclined to the pressing axis, and
• a rolling element unit rotatable with respect to the pressing axis, with a pressure ring surrounding the pressing axis and a plurality of rotationally symmetrical rolling elements arranged around the pressing axis, which may be tapered at least in some areas and which are each axially supported on the pressure ring at a variable distance from the pressing axis and are rotatably mounted about their own axis and are slidably mounted in the associated pocket-shaped receptacle so as to be displaceable along the axis of the latter,

wherein the ring die and/or the rolling element unit is acted upon by a rotary drive causing its rotation about the pressing axis and wherein the rolling element unit and/or the ring die is further acted upon by a rotary drive causing the axial adjustment of the rolling element unit and the ring die relative to each other along the press axis.

Fig. 1

in perspektivischer Ansicht einen Axialschnitt durch eine erste erfindungsgemäße Radialpresse und

Fig. 2

einen Ausschnitt durch eine Radialpresse gemäß einem zweiten Ausführungsbeispiel der Erfindung; weiterhin veranschaulicht

Fig. 3

eine Umsetzung der Erfindung in modifizierter Form,

Fig. 4

eine andere Umsetzung der Erfindung in modifizierter Form,

Fig. 5

eine nochmals andere Umsetzung der Erfindung in modifizierter Form,

Fig. 6

eine nochmals andere bevorzugte Ausführungsform der Erfindung,

Fig. 7

eine abermals andere Ausführungsform der Erfindung,

Fig. 8

einen Teilbereich der Radialpresse nach Fig. 7 in vergrößerter Darstellung und

Fig. 8a

ein Detail der Fig. 8 in einem Schnitt.

In the following, the present invention is explained in more detail using several embodiments illustrated in the drawing.

Fig.1

in perspective view an axial section through a first radial press according to the invention and

Fig. 2

a section through a radial press according to a second embodiment of the invention; further illustrated

Fig.3

an implementation of the invention in a modified form,

Fig.4

another implementation of the invention in modified form,

Fig.5

yet another implementation of the invention in a modified form,

Fig.6

yet another preferred embodiment of the invention,

Fig.7

yet another embodiment of the invention,

Fig.8

a section of the radial press according to Fig.7 in enlarged view and

Fig. 8a

a detail of the Fig.8 in one cut.

The Fig.1 The radial press shown in the drawing, which serves for the radial deformation of a workpiece W - illustrated by way of example by a ring 1 - comprises as main components a housing-like base 2 with a bottom 3, a casing section 4 and a cover 5, a roller bearing 6 fixed to the base 2 by means of a first roller bearing 6 and a second Rolling bearing 7 has a hollow ring die 8 which is rotatably mounted with respect to a pressing axis X, and a rolling element unit 9 which is rotatable with respect to the pressing axis X. The ring die 8 has an inner contour 10 which tapers in the direction of the pressing axis X and is rotationally symmetrical with respect to the pressing axis X and has a truncated cone-shaped geometry (half cone angle approx. 15°). And the rolling element unit 9 comprises a pressure ring 11 which surrounds the pressing axis X and five truncated cone-shaped rolling elements 12 (rolling cone 13 with a double cone angle of approx. 15°) which are arranged around the pressing axis X and which can roll on the inner contour 10 of the ring die 8.

The rolling cones 13 are rotatably supported on the pressure ring 11, at a variable distance from the pressing axis X. For this purpose, each of the rolling cones 13 is rotatably mounted on a bearing piece 15 by means of an associated bearing 14, which in turn is guided displaceably on the pressure ring 11 on a sliding surface 16. The sliding surfaces 16 - arranged at the base of the guides 17 that laterally enclose the bearing pieces 15 and inclined to the pressing axis X - are designed on the surface of replaceable U-shaped sliding bearing plates 18.

The rolling element unit 9 is acted upon by a feed drive which effects its axial adjustment along the pressing axis X. This comprises a pressure tube 19 which is coaxial with the pressing axis X and on which the pressure ring 11 is supported via a tapered roller bearing 20 and which is guided on the cover 5 of the base 2 via a linear guide 21 so that it can be moved (but is secured against rotation) along the pressing axis X. A linear actuator (not shown, designed for example as an electric spindle drive flanged to the cover 5 of the base 2) acts on the pressure pipe 19.

The ring die 8 is acted upon by a rotary drive which causes it to rotate about the pressing axis X. This comprises a rotary actuator (not shown, for example designed as an electric motor flanged to the casing section 4 of the base 2) and a drive belt 22 which couples this to the ring die 8, the casing section 4 of the base 2 having an opening (not shown) for the drive belt 22. The drive belt 22 wraps around the ring die 8 between the first roller bearing 6, which forms a radial support for the ring die 8 and is designed as a ball bearing 23, and the second roller bearing 7, which forms an axial/radial support for the ring die 8 and is designed as a tapered roller bearing 24. The inner ring 25 of the second roller bearing 7 is arranged on an annular projection 27 of the bottom 3 of the base 2, which surrounds a central opening 26 of the base 2 extending around the press axis X.

Fig.2 illustrates, within the scope of the relevant section, a rolling element unit 9 compared to Fig.1 modified embodiment. In this case, the pressure ring 11 is part of a rolling element cage 28, which has an annular wall 29 with a number of openings 30 corresponding to the number of rolling elements 12. In each of the openings 30, a rolling element 12 is rotatably mounted on its two end faces. For this purpose, the - again essentially The frustoconical rolling elements 12 each have a pin 31 on their front sides, which engages in the inner ring of a tapered roller bearing 32, the outer ring of which is accommodated in a bearing cup 33. A replaceable cup-shaped plain bearing plate 34 is placed on this, which slides on a sliding surface 16 that delimits the associated opening 30 of the rolling element cage 28. The cup-shaped plain bearing plate 34 is in this case adapted in terms of its dimensions to the dimensions of the opening 30 in such a way that the displacement along the sliding surfaces 16 takes place in the direction of the pressing axis X and away from it laterally, ie in the circumferential direction.

Since all other aspects of the embodiment according to Fig. 2 A person skilled in the art will be able to understand the above explanation of the Fig.1 illustrated first embodiment, reference is made to the latter to avoid repetition. It should be emphasized that Fig. 2 , as well as Fig.1 , it can be clearly seen that despite a balance of the forces acting on the rolling cones, as a result of the relative osculation of the rolling cones 13 to the (concave) inner contour 10 of the ring die 8, there is a significantly lower surface pressure in the respective contact area than in the respective contact area of the respective rolling cone 13 on the (convex) outer contour of the workpiece W. In other words, the geometric conditions on the workpiece W result in a correspondingly increased radial pressure compared to the pressure between the ring die 8 and the rolling cone 13 and thus a correspondingly high forming effect. How the contact zones of the rolling cones 13 on the ring die 8, the contact zones of the rolling cones 13 on the workpiece W typically also taper slightly in the direction of the tip of the rolling cones 13, which can possibly be technically used for an increasing pressure in this direction.

According to Fig.3 is, in a modification to the Figures 1 and 2 illustrated embodiments of the invention, not the ring die 8.1, on which the rotary drive acts, but rather the rolling element unit 9.1. In this respect, the drive belt 22 wraps around a sleeve 35 formed on the pressure ring 11.1 of the rolling element unit 9.1, which also serves to support the rolling element unit 9.1 so that it can rotate with respect to the press axis X - via two rolling bearings 36. Conversely, again in a modification to the Figures 1 and 2 illustrated embodiments of the invention, the feed drive is not directed to the rolling element unit 9.1, but rather to the ring die 8.1. In an exemplary embodiment, the feed drive is designed hydraulically in that an annular collar 37 provided on the outer circumference of the ring die 8.1 is guided in a sealing manner in a cylindrical bore 38 of the base 2.1 and divides this into two counter-rotating hydraulic working spaces 40, each of which can be acted upon via a fluid connection 39. In this specific embodiment, the ring die 8.1 is not designed for rotation around the press axis X, which means that the workpiece W rotates under the influence of the rolling elements 12.1 rolling on it and on the inner contour 10.1 of the ring die 8.1. It would be clear However, in order to avoid rotation of the workpiece W, rotation of the ring die 8.1 about the pressing axis X can easily be achieved, for example by (cf. Fig.5 ) the ring die 8.1 is rotatably mounted in a bearing sleeve, which in turn is mounted in the base 2.1 along the press axis X - adjustable by means of the feed drive.

Since all other aspects of the radial press are Fig.3 A person skilled in the art will be able to understand the above explanation of the Figures 1 and 2 illustrated embodiments, reference is made to the latter to avoid repetition.

The Fig.4 The modification illustrated differs from that according to Fig.3 essentially solely by the shape of the rolling elements 12.2. Because these are cylindrical here. In this way, the radially deformed workpiece W does not have a cylindrical shape in the forming zone, but rather a conical shape, corresponding to the conical inner contour 10.2 of the ring die 8.2. Furthermore, in particular with regard to the other aspects of the rolling element unit 9.2 including the pressure ring 11.2 and the base 2.2, reference is made to the above explanations of the Figures 1-3 referred to.

The Fig.5 The modification illustrated is conceptually based on the Fig.4 The decisive differences relate to the ring die 8.3, namely as follows: The inner contour 10.3 of the ring die 8.3 is not rotationally symmetrical here; rather, it has pocket-shaped grooves arranged evenly around the pressing axis X and inclined to the pressing axis X. Receptacles 41 for the rolling elements 12.3. The - again cylindrical - rolling elements 12.3 therefore do not roll on the inner contour 10.3 of the ring die 8.3, but rather they rotate about their own axis in the associated receptacle 41, the inner surface of which corresponds to a cylinder segment partially enclosing the associated rolling element 12.3. The ring die 8.3 is rotatably accommodated - via two roller bearings 42 - in a bearing sleeve 43, which in turn is slidably accommodated in the base 2.3 along the press axis X. The feed drive is again designed hydraulically, for example, in that an annular collar 44 provided on the outer circumference of the bearing sleeve 43 is guided in a sealing manner in a cylindrical bore 45 of the base 2.3 and divides this into two counter-rotating hydraulic working spaces 47, each of which can be acted upon via a fluid connection 46. However, it would also be easy to see how, as with the radial presses after the Figures 3 and 4 , an electric feed drive (for example via an electric spindle drive). This radial press, in which the rolling element unit 9.3 and the ring die 8.3 clearly rotate in the same direction and at the same speed about the press axis X, obviously requires that the workpiece W is held in a holder which prevents it from rotating about the press axis X.

The two modified embodiments according to the Figures 6 and 7 , in the intended use of which the workpieces to be formed can typically be fixed in position and rotation with respect to the (again housing-like) base 2, are explained to a specialist from the above detailed explanations of the other embodiments. Unnecessary repetitions regarding the functioning of the radial press and the function of the individual components are omitted. However, explicit attention is drawn to the rotatable, radial and axial force-absorbing bearing of the rolling element unit 9 - which is rotatable about the press axis X by the motor M by means of a belt drive (see the drive belt 22) - on a hollow pin 48 mounted on the lower cover 5 of the base 2. Part of the rolling element unit 9 is - according to the Fig. 2 illustrated concept - a rolling element cage 28 with openings. In these - each on associated sliding guides - the two bearing pieces 49, on which the respective associated rolling cone 13 is mounted so as to be rotatable about its axis A, are mounted so as to be displaceable towards and away from the press axis X. The two-part structure of the rolling element cage 28, consisting of a lower part 50 and an upper part 51 fixed to it, is clearly visible, with the front side of the lower part 50 provided with sliding guides acting as the pressure ring 11.

At this point, it should be emphasized that the illustrated design of the drive with an (external) motor, which is coupled to the driven part via a belt drive, is only one conceivable configuration. Other drive concepts are equally possible. For example, an (integrated) hollow shaft drive using a torque motor, the output of which is directly coupled to the pressure ring or the ring die. A direct rotary drive of the rolling elements is also conceivable.

The ring matrix 8 is - according to the Fig.5 illustrated concept - freely rotatable about the press axis X in a hollow piston-like bearing sleeve 43, which, in order to effect a radial feed of the rolling cones 13, is axially adjustable by means of a corresponding loading of the two hydraulic working chambers 47 in the cylindrical bore 45 of the base 2. The support of the outer and inner ring of the (upper) bearing of the ring die 8 - designed as a tapered roller bearing 52 - by means of diagonally acting shoulders on the bearing sleeve 43 and the ring die 8 allows the transmission of particularly large axial forces from the bearing sleeve 43 to the ring die 8. The same applies to the bearing of the rolling element unit 9 on the hollow pin 48 - which is equally axially loaded.

Illustrated in the Figures 6 and 7 two more design features. After Fig.6 the inner contour 10 of the ring die 8 is not mathematically exactly frustoconical, but rather (see radius R) slightly convex. And after Fig.7 The inner contour 10 of the ring die 8 has spiral or helical grooves 53 which serve to remove abrasion, dirt or the like.

In the Figures 8 and 8a , which is a part of the radial press according to Fig.7 in an enlarged view, the guidance of the rolling cones 13 in the rolling element cage 28 is particularly clearly visible. The sliding bearing of the bearing pieces 49 on plain bearing plates 60 can be seen. It is also shown how the bearing pieces are each supported by means of two return springs 54 in the form of helical compression springs are preloaded radially outwards so that the rolling cones 13 are constantly in contact with the inner contour 10 of the ring die 8. The - in Fig. 8a for reasons of illustration, partially shown - return springs 54 are accommodated in cavities 55 of approximately cylindrical shape, which are defined by two half cylinders each. A first half cylinder 56 is designed to the side of the respective bearing piece 49 and is radially outwardly limited by a base 57; the other, corresponding half cylinder 58 is designed on the roller bearing cage 28 and is radially inwardly limited by a base 59. The return spring 54 accommodated in the respective cavity 55 is thus supported on the one hand on the base 57 of the respective half cylinder 56 and on the other hand on the base 59 of the corresponding half cylinder 58. The details of the Figures 8 and 8a a person skilled in the art from the above explanations of the other figures.

Claims (27)

1. A radial press, comprising

   - a base (2),

   - a hollow annular die (8) mounted rotatably thereon relative to a press axis (X) and having an inner contour (10) that tapers in the direction of the press axis (X) and is rotationally symmetrical relative to the press axis (X) and

   - a rolling-element unit (9) capable of rotating relative to the press axis (X) and having a thrust ring (11) surrounding the press axis (X) and a plurality of rotationally symmetric rolling elements (12), which are disposed around the press axis (X) and taper at least in regions, which are rotatably axially braced on the thrust ring (11) with variable distance to the press axis (X), and which can roll along the inner contour (10) of the annular die (8),

   wherein a rotary drive acts on the annular die (8) and/or on the rolling-element unit (9), causing their rotation around the press axis (X), and wherein furthermore a feed drive acts on the rolling-element unit (9) and/or on the annular die (8), causing axial adjustment of the rolling-element unit (9) and of the annular die (8) relative to one another along the press axis.
2. The radial press of claim 1, characterized in that the inner contour (10) of the annular die (8) and the rolling elements (12) have a substantially frustoconical basic shape.
3. The radial press of claim 2, characterized in that twice the cone angle of the rolling elements (12) corresponds substantially to half the cone angle of the inner contour (10) of the annular die (8).
4. The radial press of claim 2 or claim 3, characterized in that the inner contour (10) of the annular die (8) and the rolling elements (12) are constructed in geometrically exactly frustoconical manner.
5. The radial press of claim 2 or claim 3, characterized in that the rolling elements (12) are made slightly convex, especially in that their cone angle varies continuously over its extent along their own axis.
6. The radial press of one of claims 1 to 5, characterized in that the rolling elements (12) are mounted with the ability to rotate on bearing pieces (15), which are displaceably guided along the thrust ring (11) on sliding faces (16).
7. The radial press of claim 6, characterized in that the sliding faces (16) are respectively constructed by the surface of an exchangeable sliding-bearing plate (18).
8. The radial press of claim 6 or claim 7, characterized in that the sliding faces (16) are inclined relative to the press axis (X).
9. The radial press of one of claims 6 to 8, characterized in that the bearing pieces (15) are guided in undercut guides (17) of the thrust ring (11) in such a manner that they cannot be lifted out.
10. The radial press of one of claims 1 to 9, characterized in that the base (2) is constructed in the form of a housing, wherein a shell portion (4) of the base surrounds the annular die (8) at least partly.
11. The radial press of one of claims 1 to 10, characterized in that the feed drive comprises a thrust tube (19) coaxial with the press axis (X).
12. The radial press of claim 11, characterized in that on the base, the thrust tube (19) is guided displaceably along the press axis (X) via a linear guide (21).
13. The radial press of one of claims 1 to 12, characterized in that an odd number of rolling elements (12) is provided.
14. The radial press of one of claims 1 to 13, characterized in that the rolling-element unit (9) has preloading springs, which preload the rolling elements (12) outwardly for bearing on the inner contour (10) of the annular die (8).
15. The radial press of one of claims 1 to 14, characterized in that the surface of the rolling elements (12) is profiled.
16. The radial press of claim 15, characterized in that a helical profiling is provided.
17. The radial press of claim 15, characterized in that the rolling elements (12) have a nubbed surface.
18. The radial press of claim 15, characterized in that the rolling elements (12) have annularly closed micro-serration extending over the respective circumference.
19. The radial press of one of claims 1 to 18, characterized in that the rotary drive acts exclusively on the annular die (8).
20. The radial press of one of claims 1 to 19, characterized in that the feed drive acts exclusively on the rolling-element unit (9).
21. The radial press of one of claims 1 to 20, characterized in that the bearing of the annular die (8) on the base (2) comprises two spatially separated bearings (6, 7), wherein the point of application of the rotary drive on the annular die (8) is located between the two bearings (6, 7).
22. The radial press of one of claims 1 to 21, characterized in that the base (2) has, adjacent to the end of the annular die (8) associated with the smaller diameter of the inner contour (10), an opening (26) extending around the press axis (X).
23. The radial press of one of the claims 1 to 22, characterized in that the annular die is constructed in several parts in such a way that it comprises a support ring and an insert, which is received exchangeably therein and defines the inner contour.
24. The radial press of one of claims 1 to 23, characterized in that the thrust ring (11) is part of a rolling-element cage (28), which is provided with a wall (29) having openings (30), in which the rolling elements (12) are rotatably mounted at their two ends.
25. The radial press of claim 1, characterized in that substantially cylindrical rolling elements (12.2, 12.3) or rolling elements that widen at least in some regions are used instead of rolling elements (12) that taper at least in some regions.
26. The radial press of claim 1, characterized in that the annular die (8.1; 8.2) is not rotatable relative to the press axis (X) but to the contrary is co-rotatable with the base (2.1; 2.2).
27. The radial press of claim 1, characterized in that the inner contour (10.3), tapering in the direction of the press axis (X'), of the annular die (8.3) is not rotationally symmetrical, but to the contrary has a plurality, disposed uniformly around the press axis (X) and inclined relative to the press axis (X), of pocket-shaped receptacles (41) for the rolling elements (12.3), wherein the rolling elements (12.3), which are rotationally symmetrical but do not necessarily taper in some regions, for their part roll not on the inner contour (10.3) of the annular die (8.3), but to the contrary are respectively mounted rotatably around their own axis and in slidingly displaceable manner in the associated pocket-shaped receptacle (41), along the axis of the latter.

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