Radial press
Patent Information
- Application Number
- EP2025713544
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-03-18
- Filing Date
- 2025-03-17
- Publication Date
- 2026-01-21
AI Technical Summary
Radial presses in yoke press design face limitations at high pressing forces due to deformation of asymmetrical housing or frame structures, leading to increased material and manufacturing costs.
A radial press design featuring a drive carrier that wraps around a curved support surface, with hydraulic cylinder-piston units integrated into the drive carrier, allowing for uniform stress distribution and minimal local stress peaks, and a frame that nests against the drive carrier with slippage to manage high pressing forces efficiently.
The design achieves a favorable power-to-weight ratio, enabling high pressing forces with reduced material expenditure and manufacturing costs, while ensuring easy component interchangeability and early detection of asymmetries to prevent irreversible workpiece damage.
Smart Images
Figure EP2025057245_25092025_PF_FP_ABST
Abstract
Description
[0001] Radial press
[0002] The present invention relates to a radial press in yoke press design, comprising a fixed yoke, a movable yoke, a press drive effecting the closing movement of the movable yoke relative to the fixed yoke and a one-piece, annularly closed frame surrounding these components, wherein the fixed yoke and the movable yoke together define a tool installation space in which a pressing tool with a plurality of pressing jaws arranged around a pressing axis is received.
[0003] Radial presses in yoke press design have been known for decades and have proven themselves in practical use. Reference can be made to DE 41 35 465 A1 as an example of the relevant state of the art. Yoke presses with a housing or frame structure featuring a lateral feed opening through which the workpiece can be inserted from the side into the opened pressing tool (cf. DE 199 40 744 A1 and DE 198 17 882 A1) facilitate handling in various application situations or are even indispensable for certain applications. However, they reach their limits at very high pressing forces due to the risk of deformation of the (asymmetrical housing or frame structure). In this case, radial presses designed in yoke press design are advantageous, which either have a tie rod coupled to the movable yoke on each side of the tool installation space (cf. DE 41 35 465 A1, see above).) or have a circumferentially closed frame structure coupled to the fixed yoke. Such radial presses, which also correspond to the generic design described above, are known by name from US 8 266 968 B2, DE 199 12 976 A1, CA 2 005 264 A, and DE 10 2016 102 275 A1.
[0004] Given the increasing demand for radial pressing operations performed with very high pressing forces, the present invention aims to provide a generic radial press characterized by a particularly favorable power-to-weight ratio. In other words, the objective is to provide a generic radial press with a high ratio of the radial press's performance (in terms of maximum pressing force) to its weight. A favorable power-to-weight ratio in the above sense is particularly important for radial presses designed for particularly high pressing forces (e.g., more than 15,000 kN); this allows the manufacturing costs (which depend heavily on the amount of material used) to be kept within a reasonable range.
[0005] The task described above is solved by using a radial press of the generic type
[0006] - the press drive comprises at least two parallel oriented hydraulic cylinder-piston units spaced apart from each other transversely to the press axis,
[0007] - a drive carrier is provided, which the frame wraps around at least 160°, nestled against a curved support surface of the drive carrier, and
[0008] - the drive carrier has a number of receptacles corresponding to the number of hydraulic cylinder-piston units, into which the pistons of the hydraulic cylinder-piston units are inserted.
[0009] Through the synergistic interaction of their various
[0010] The inventive design features
[0011] Radial presses are characterized by the possibility of very uniform stress distribution with only minimal local stress peaks. As a result, even the reaction forces arising at very high pressing forces can be controlled with structures which – measured against the performance of the radial press and in comparison to radial presses with previously known designs – can be manufactured with relatively low material expenditure and thus cost-effectively. And the comparatively low weight of the radial press – again measured against its performance – is also an immense advantage of the present invention. A further advantage of high practical relevance associated with the design of the radial press according to the invention is the possibility of optimizing the radial press without any loss of performance with regard to particularly easy interchangeability of the yokes and components of the press drive.
[0012] According to a first preferred development of the invention, the drive carrier support surface describes a section of a circular cylinder. This not only has a direct positive effect on the stress distribution occurring in the frame. A further advantage of this design is the particularly simple possibility of a defined, deliberate slippage between the frame and the drive carrier in the event of a deliberately calculated expansion of the frame during the pressing process. In this light, it is further advantageous if the frame and the drive carrier are only fixed to one another locally, namely at the apex of the frame, while the frame otherwise rests against the drive carrier support surface in a sliding manner. The advantages described are particularly pronounced if the frame is nestled against the curved support surface of the drive carrier and wraps around it at 180°.A further, highly advantageous development of the invention is characterized in that the cylinders of the hydraulic cylinder-piston units are an integrated part of the drive carrier, with the cylinders of the hydraulic cylinder-piston units forming the cylinders of the hydraulic cylinder-piston units in its receptacles. The static-mechanical strength requirements for the cylinders of the hydraulic cylinder-piston units are thus met by the receptacles formed integrally with the drive carrier. However, this does not preclude the internal lining of the cylinders of the hydraulic cylinder-piston units with a separate liner, particularly in the case of a drive carrier manufactured using a casting process such as gray cast iron. This development offers particular advantages when the press drive comprises exactly two hydraulic cylinder-piston units.It is also expedient if there is a displaceability transverse to the axis of the respective hydraulic cylinder-piston unit between the pistons of the hydraulic cylinder-piston units and the movable yoke - for example, realized by a pair of sliding surfaces; in this way, possible transverse forces on the pistons are minimized, which contributes to mechanical protection of the hydraulic cylinder-piston units, thus extending their service life.
[0013] Particularly when the press drive comprises a large number of hydraulic cylinder-piston units, a different design for integrating the press drive into the drive carrier can prove very advantageous. This is where the hydraulic cylinder-piston units are separate elements whose cylinders are inserted into the mounts of the drive carrier. In this case, even commercially available cylinder-piston units can be used, which ideally rest on the drive carrier without any torque.The statement in the claim, according to which the pistons of the hydraulic cylinder-piston units may be immersed in the respective associated receptacle provided on the drive carrier, as the above explanations of a preferred embodiment of the invention show, can thus be (mis)understood to mean that the pistons functionally interact with the receptacles; in this respect, it is merely a matter of a geometric relationship.
[0014] Depending on the individual design of the radial press according to the invention, at least one hydraulic pressure intensifier is assigned to the hydraulic cylinder-piston units of the press drive. In typical applications of the present invention, this is preferably structurally integrated into the drive carrier by having a housing formed integrally with the rest of the drive carrier. However, in individual cases, it may also prove advantageous for the hydraulic pressure intensifier to be a separate component mounted on the drive carrier, although this typically results in a higher overall weight of the radial press.
[0015] According to the inventive support of the drive carrier on the frame, according to yet another preferred embodiment of the radial press according to the invention, it is advantageous if the frame, nestled against a curved support surface of the stationary yoke, wraps around the latter by at least 160°, particularly preferably 180°, whereby the yoke support surface can in particular describe a section of a circular cylinder. The advantages presented and explained above apply accordingly here.
[0016] Regarding the arrangement of the two yokes, according to yet another preferred embodiment of the invention, the fixed yoke forms a lower yoke and the movable yoke forms an upper yoke. This applies in particular to radial presses designed for particularly large workpieces (e.g., 0 > 500 mm) and particularly high pressing forces (e.g., > 10,000 kN) that must be applied to them; in this case, the yokes have a substantial mass, which, when the movable yoke is arranged as the upper yoke, increases the pressing force.
[0017] According to yet another preferred embodiment of the present invention, the frame has two arc sections, each describing a 180° arc, and two tensile sections connecting these sections and parallel to each other and to the orientation of the hydraulic cylinder-piston units. Said orientation of the tensile sections ensures that they are free of shear stresses, i.e., are subjected exclusively to tensile stress. This, in turn, also contributes to optimal stress distribution and thus the best possible utilization of the material used. It is particularly advantageous if the extension of the frame parallel to the press axis is smaller, at least on some of the arc sections, than on the tensile sections.The greater extension of the frame parallel to the pressing axis in the area of the two tension sections compared to the curved sections ensures increased resistance of the frame to deformations that could lead to limited quality of the radial pressing (e.g., conicity of the pressing). This is also contributed to if, according to yet another preferred development of the invention, guides for the movable yoke are provided in the area of the tension sections of the frame. It is particularly advantageous if guide elements fixed to the movable yoke engage in associated grooves of the tension sections of the frame and are guided there for displacement. Such a design of the guide for the movable yoke does not hinder the desired, defined expansion of the tension sections during the pressing process.For this form of guiding the movable yoke, the frame design explained above, in which the tension sections are wider than the curved sections in certain areas, parallel to the pressing axis, proves to be particularly advantageous. In individual cases, however, it may also be advantageous if the frame has the same extension parallel to the pressing axis throughout, i.e., on both its tension sections and its curved sections, and even if the tension sections are narrower than the curved sections.
[0018] According to yet another preferred development of the radial press according to the invention, in radial presses with a press drive comprising exactly two hydraulic cylinder-piston units, at least one advance and return stroke adjuster acting on the movable yoke is arranged on the drive carrier between the cylinders of the hydraulic cylinder-piston units. Particularly preferably, two (or even more) such advance and return stroke adjusters are provided in the form of hydraulic cylinder-piston units, which are oriented parallel and spaced apart from one another in the direction of the press axis. Preferably, a stiffening web of the drive carrier extends between two advance and return stroke adjusters, oriented transversely to the press axis, and at its end, merges into its receptacles, possibly thus into the cylinders of the two hydraulic cylinder-piston units of the press drive formed by these.Particularly preferably, the at least one advance and return stroke adjuster is replaceable without further disassembly work; this enables the radial press to be adapted to different requirements or tasks without any significant effort.
[0019] Furthermore, it is highly advantageous if at least two, preferably four, position sensors are installed between the fixed yoke and the movable yoke, whose signals are transmitted to the press control system. This allows potential asymmetries in the pressing to be identified early on, before irreversible damage to the workpiece occurs, which in turn allows the pressing to be corrected. This is a crucial factor, particularly given that the radial press according to the invention, due to its design, is primarily used for the radial forming of particularly large, complex, and expensive workpieces. By detecting a potential faulty radial forming process early on and exploiting the possibilities for corrective action, scrap can be avoided, which represents a very direct cost aspect.
[0020] The present invention will be explained in more detail below with reference to two preferred embodiments illustrated in the drawings. Fig. 1 shows the radial press according to a first embodiment in perspective view, Fig. 2 shows a front view of the radial press according to Fig. 1, Fig. 3 shows a side view of the radial press according to Figs. 1 and 2 from the left, Fig. 4 shows a vertical section through the radial press according to Figs. 1 to 3 along the line IV-IV in Fig. 2,
[0021] Fig. 5 is a plan view of the radial press according to Figures 1 to 4,
[0022] Fig. 6 is a horizontal section through the radial press according to Figures 1 to 5 along the line VI-VI in Fig. 2 and
[0023] Fig. 7 shows a horizontal section through the radial press according to Figures 1 to 6 along the line VII-VII in Fig. 2. In contrast,
[0024] Fig. 8 is a partially sectioned front view of the upper region of a radial press according to the invention according to a second embodiment.
[0025] The radial press illustrated in Figures 1 to 7 of the drawing, which is designed as a yoke press, comprises a fixed yoke 1, a movable yoke 2, and a press drive 3 which effects the closing movement of the movable yoke 2 relative to the fixed yoke 1. The fixed yoke 1 and the movable yoke 2 together define a tool installation space 4 in which a pressing tool 5 with a plurality of pressing jaws 6 arranged around a pressing axis X is accommodated. By means of support and control surfaces of the two yokes 1, 2 and the pressing jaws 6, which interact with one another in a known manner, a closing movement of the movable yoke 2 (arrow A) is converted into a radially inward movement of the pressing jaws 6 oriented in the direction of the pressing axis X. This concept, which constitutes the essence of yoke presses, and its constructive implementation are comprehensively described in the prior art and therefore require no further explanation here.In the radial press shown, the fixed yoke 1 forms a lower yoke 7, and the movable yoke 2 forms an upper yoke 8. The press drive 3 is arranged above the upper yoke 8 and acts directly on it. The frictional connection (between the lower yoke 7 and the press drive 3) is achieved via a one-piece frame 9—namely, a mechanically reworked cast part—that surrounds the lower yoke 7, upper yoke 8, and press drive 3 in a closed ring.
[0026] The press drive 3 comprises two hydraulic cylinder-piston units 10 oriented parallel to one another with vertical axes parallel to the closing movement A of the upper yoke 8. The two cylinder-piston units 10 are arranged side by side, transversely to the press axis X, i.e., spaced apart from one another in a plane perpendicular to the press axis X. The two cylinders 11 of the hydraulic cylinder-piston units 10 are each formed by a receptacle 38 integrally formed on a drive support 12, similar to a downwardly open bushing; in this way, they are an integrated part of the drive support 12, which further comprises webs and ribs that stiffen the structure, in particular a stiffening web 13 extending transversely to the press axis X between the two receptacles 38 or the cylinders 11 formed by them, and merging into the latter at the ends.The drive support 12 is limited at the top by an end bend 14, which is widened in the orientation of the press axis X and whose outer surface 15 forms a curved support surface 16 for the frame 9. The end bend 14 has two extended foot sections 17, which merge into the bottoms 18 of the cylinders 11 of the two hydraulic cylinder-piston units 10. The curved support surface 16 on the end bend 14 merges into support surface sections 19 on the cylinders 11 of the hydraulic cylinder-piston units 10. The entire drive support surface 20, i.e. the curved support surface 16 on the end bend 14 together with the two support surface sections 19 on the cylinders 11, each forming an extension, lies on a 180. 0-section of a circular cylinder. The frame 9 thus has an upper arc section 21, which describes a 180° arc, and, nestled against the drive carrier support surface 16, wraps around the drive carrier 12 at 180°.
[0027] The outer surface 22 of the fixed yoke 1, i.e., in this case, the lower yoke 7, facing away from the tool installation space 4, describes—in a manner comparable to the drive carrier 12 explained above—a yoke support surface 23, which also lies on a 180° segment of a circular cylinder. And the frame 9 has a lower curved section 24, which describes a 180° arc and, nestled against the curved yoke support surface 23, wraps around the lower yoke 7 at 180°. It should be noted that the two curved sections 21, 24 of the frame 9 bear flat against the drive carrier support surface 16 and the yoke support surface 23, respectively; However, they are not fixed to the drive carrier 12 or the lower yoke 7 in a way that would hinder or even prevent load-induced expansion of the respective curved section 21, 24 with slippage on the support surface 16, 23 of the drive carrier 12 or the lower yoke 7.In this respect, the position of the drive support 12 and the lower yoke 7 on the frame 9 is secured only at the upper vertex of the upper curved section 21 and the lower vertex of the lower curved section 24, respectively, and solely by clamping by means of an upper pair of claws 25 fixed to the drive support 12 and a lower pair of claws 26 fixed to the lower yoke 7. Bores, particularly threaded holes, on the curved sections 21, 24 of the frame 9 are thus avoided. The frame 9 further comprises two tension sections 27 connecting the two curved sections 21, 24 to one another, parallel to one another and to the orientation of the hydraulic cylinder-piston units 10.A widening of the two tension sections 27 relative to the curved sections 21, 24 such that the extension of the frame 9 parallel to the pressing axis X is less on at least some of the curved sections 21, 24 than at the tension sections 27, increases the rigidity of the frame 9 about a horizontal axis oriented transversely to the pressing axis X and transversely to the direction of movement A of the upper yoke 8 and thus counteracts canting of the lower yoke 7 and drive carrier 12 relative to one another. The corresponding widened areas of the two tension sections 27 are also designed to guide the (movable) upper yoke 8. For this purpose, the tension sections 27 of the frame 9 have grooves 28 extending parallel to the direction of movement A of the upper yoke 8. Guide elements 29 in the form of guide plates 30 fixed to the upper yoke 8 engage (displaceably) in these grooves.Therefore, no threaded holes or other bores are required to guide the upper yoke 8 to the frame 9. This supports the integrity of the frame and thus promotes an optimal, uninterrupted flow of force.
[0028] The hydraulic cylinder-piston units 10 of the press drive 3 are designed as single-acting hydraulic cylinders. The upper yoke 8 is raised to open the radial press by means of two separate return stroke adjusters 31 acting on the upper yoke 8. These are arranged between the cylinders 11 of the two hydraulic cylinder-piston units 10. They are designed as hydraulic cylinder-piston units 32, which are oriented parallel to one another at a distance from one another in the direction of the press axis X. The cylinders 33 of the two return stroke adjusters 31 are connected to the drive carrier 12, namely by ribs 34, which, in the sense of an inverted T-profile, project laterally from the stiffening web 13, extending between the two cylinders 11 of the hydraulic cylinder-piston units 10 of the press drive 3.
[0029] The return stroke adjusters 31, designed as combined rapid and return stroke adjusters, also undertake an initial, comparatively high-speed closing movement of the upper yoke 8 during the phase until the pressing jaws 6 of the pressing tool 5 rest against the workpiece inserted into it. During this phase, the hydraulic cylinder-piston units 10 of the press drive 3 are switched to a post-suction mode, in which hydraulic fluid flows from the two overhead post-suction tanks 36—each flanged to the drive carrier 12 via a valve block 35—into the expanding working spaces of the hydraulic cylinder-piston units 10.
[0030] Two electrical displacement transducers 37 are located between the lower yoke 7 and the upper yoke 8, whose signals are fed to the machine control system. Two additional displacement transducers 37 can be arranged in a mirror image on the other end face of the radial press.
[0031] The radial press according to the second embodiment, of which the upper area is illustrated in Fig. 8 of the drawing in a partially sectioned front view, is explained directly from the above explanations of the first embodiment illustrated in Figs. 1 to 7, unless the deviations from the first embodiment explained below are concerned.
[0032] The press drive 3' here comprises three hydraulic cylinder-piston units 10', each with a cylinder 11' and a piston 39'. These cylinder-piston units 10' represent separate components, i.e. physically independent of the drive carrier 12'. They are each inserted into a holder 38' integrated into the drive carrier 12', i.e. partially received in a free space 41 formed by the respective holder 38'. The load-transmitting end-face support of the cylinders 11' on the drive carrier 12' is torque-free, i.e. via adjoining sliding surfaces with a spherical cap geometry.
[0033] In this embodiment, the two return stroke adjusters 31' are offset diagonally from the center of the radial press, namely the return stroke adjuster provided on the side facing away from the viewer, of which the piston rod 40 is shown in Fig. 8, to the left in a plane lying between the left cylinder-piston unit 10'a and the middle cylinder-piston unit 10'b, and the return stroke adjuster provided on the side facing the viewer, not visible in Fig. 8, to the right in a plane lying between the middle cylinder-piston unit 10'b and the right cylinder-piston unit 10'c.
[0034] It should be noted that details shown in Figs. 1 to 7, such as the valve blocks 35 and the suction tanks 36, are not shown in Fig. 8 for the sake of simplicity, better clarity, and clarity of illustration. Obviously, similar components can also be implemented in the radial press according to Fig. 8. In a modified variant of the embodiment according to Fig. 8, it is possible to arrange the three hydraulic cylinder-piston units 10' a, 10' b, and 10' c of the press drive not in one plane, but rather to offset the middle cylinder-piston unit 10' b in the direction of the press axis relative to the plane defined by the left cylinder-piston unit 10' a and the right cylinder-piston unit 10' c. By targeted, controlled individual loading of the various hydraulic cylinder-piston units, the center of the resulting force exerted by the press drive 3' on the movable yoke 2 can be shifted in the direction of the press axis.This enables the pressing force ratios to be influenced during the ongoing pressing process and thus without correcting the position of the workpiece in the pressing tool, specifically to compensate for a possible asymmetry, such as may arise, for example, due to an asymmetrical workpiece geometry and / or an off-center position of the workpiece in the pressing tool – and which can be detected by differing measurement results from the displacement sensors 37 provided on the front and rear of the radial press (see Fig. 2). It is understood that this modification can also be used in radial presses according to the invention having at least three hydraulic cylinder-piston units, in which the cylinders of the hydraulic cylinder-piston units are an integrated component of the drive carrier – as in the first exemplary embodiment shown in Figs. 1 to 7.
Claims
Claims 1. Radial press in yoke press design, comprising a fixed yoke (1), a movable yoke (2), a press drive (3, 3') effecting the closing movement of the movable yoke (2) relative to the fixed yoke (1), and a one-piece, annularly closed frame (9) surrounding these components, wherein the fixed yoke (1) and the movable yoke (2) together define a tool installation space (4) in which a pressing tool (5) with a plurality of pressing jaws (6) arranged around a pressing axis (X) is received, characterized by the following features: - the press drive (3, 3') comprises at least two parallel oriented hydraulic cylinder-piston units (10, 10') spaced apart from one another transversely to the press axis (X); - a drive support (12, 12') is provided, which the frame (9) wraps around at least 160°, nestled against a curved support surface (16) of the drive support (12, 12'); - the drive carrier (12, 12') has a number of receptacles (38, 38') corresponding to the number of hydraulic cylinder-piston units (10, 10'), into which the pistons (39, 39') of the hydraulic cylinder-piston units (10, 10') are immersed.
2. Radial press according to claim 1, characterized in that the drive carrier support surface (16) describes a section of a circular cylinder.
3. Radial press according to claim 1 or claim 2, characterized in that the cylinders (11) of the hydraulic Cylinder-piston units (10) are an integrated part of the drive carrier (12), in that its receptacles (38) form the cylinders (11) of the hydraulic cylinder-piston units (10).
4. Radial press according to claim 3, characterized in that between the pistons (39) of the hydraulic cylinder-piston units (10) and the movable yoke (2) there is in each case a displaceability transversely to the axis of the respective hydraulic cylinder-piston unit (10).
5. Radial press according to claim 3 or claim 4, characterized in that the cylinders (11) of the hydraulic cylinder-piston units (10) are lined internally with a separate liner.
6. Radial press according to one of claims 3 to 5, characterized in that the press drive (3) comprises exactly two hydraulic cylinder-piston units (10).
7. Radial press according to claim 1 or claim 2, characterized in that the hydraulic cylinder-piston units (10') are separate elements, the cylinders (11') of which are inserted into the receptacles (38') of the drive carrier (12').
8. Radial press according to claim 7, characterized in that the cylinders (11 ') of the hydraulic cylinder-piston units (10') are mounted torque-free on the drive carrier ( 12 ' ) support .
9. Radial press according to one of claims 1 to 8, characterized in that the drive unit (3, 3') has a hydraulic pressure intensifier.
10. Radial press according to claim 9, characterized in that the hydraulic pressure intensifier is structurally integrated into the drive carrier (12, 12 ').
11. Radial press according to one of claims 1 to 10, characterized in that the frame (9) nestles against a curved support surface (23) of the fixed yoke (1) and wraps around it by at least 160°.
12. Radial press according to claim 11, characterized in that the yoke support surface (23) describes a section of a circular cylinder.
13. Radial press according to one of claims 1 to 12, characterized in that the fixed yoke (1) forms a lower yoke (7) and the movable yoke (2) forms an upper yoke (8).
14. Radial press according to one of claims 1 to 13, characterized in that the frame (9) has two arc sections (21, 24) each describing a 180° arc and two tension sections (27) connecting these to one another and parallel to one another and to the orientation of the hydraulic cylinder-piston units.
15. Radial press according to claim 14, characterized in that the extension of the frame (9) parallel to the press axis (X) is smaller at least on some of the curved sections (21, 24) than on the tension sections (27).
16. Radial press according to claim 14 or claim 15, characterized in that guides for the movable yoke (2) are provided in the region of the tension sections (27) of the frame.
17. Radial press according to claim 16, characterized in that guide elements (29) fixed to the movable yoke (29) engage in associated grooves (28) of the tension sections (27) of the frame (9).
18. Radial press according to one of claims 1 to 17, characterized in that between two cylinders (11, 11 ') of the hydraulic cylinder-piston units (10, 10') at least one advance and return stroke adjuster (31) acting between the drive carrier (12, 12 ') and the movable yoke (2) is arranged.
19. Radial press according to claim 18, characterized in that at least two advance and return stroke adjusters (31) in the form of hydraulic cylinder-piston units (32) are provided, which are spaced apart from one another in a parallel orientation in the direction of the press axis (X) and whose respective cylinder (33) is arranged on the drive carrier (12, 12 ').
20. Radial press according to claim 18 or claim 19, characterized in that the at least one advance and return stroke adjuster (31) is replaceable without further disassembly work.
21. Radial press according to one of claims 1 to 20, characterized in that at least two, preferably four displacement sensors (37) act between the fixed yoke (1) and the movable yoke (2).