RADIALPRESSE

Description

[0001] The present invention relates to a radial press with a basic structure, a plurality of press jaws arranged around a press axis and a drive unit acting on them and supported on the basic structure, by means of which the press jaws can be moved radially towards or away from the press axis. Such radial presses are known in various designs and configurations, for example as so-called "yoke presses" (see, for example, DE 41 35 465 A1, which discloses a radial press according to the preamble of claim 1 as the closest prior art, DE 199 12 976 A1 and DE 198 17 882 B4), "hollow piston presses" (see, for example, DE 101 49 924 A1) or in other designs (see, for example, DE 28 44 475 A1, DE 36 11 253 A1, DE 100 47 025 C2 and DE 33 31 721 A1).

[0002] In particular, the present invention relates, as specified in the preamble of claim 1, to a radial press designed in the manner of a yoke press, comprising an open basic structure having at least two frame elements, a plurality of press jaws arranged around a press axis, and a drive unit acting on these jaws and supported on the basic structure, by means of which the press jaws can be moved radially towards or away from the press axis, wherein the radial press comprises two yokes or control bodies that are linearly movable relative to each other in a direction of movement perpendicular to the press axis, and the drive unit has at least one drive element designed as a linear drive, defining a working axis and supported on one of the frame elements, and the press jaws are received in a tool installation space formed between the two yokes or control bodies.

[0003] The range of applications for the radial presses mentioned at the beginning has steadily expanded. Starting with the classic application, namely the permanent, secure and leak-proof attachment (by crimping) of fittings to the ends of a hose section during the production of ready-to-install hydraulic lines, a multitude of other applications have now become common, including the joining of large-diameter pipes in pipeline construction.

[0004] The present invention aims to optimize radial presses of the generic type with regard to the extensive range of applications or to make them suitable for use in new fields.

[0005] The aforementioned problem is solved by providing, in a radial press of the generic type, at least one fibrous structure surrounding the press jaws, extending in a ring-shaped closed form around the press axis in a plane essentially perpendicular to the press axis, and forming part of the basic structure, which connects the at least two frame elements – bridging at least one separation joint existing between them. Accordingly, one of the characteristic and defining features of the invention is that a fibrous structure surrounding the press jaws, extending in a ring-shaped closed form around the press axis in a plane essentially perpendicular to the press axis, is provided radially outside the press jaws.The present invention utilizes the knowledge that the forces, moments, and loads occurring outside the press jaws in radial presses of the type under discussion are, to a very significant extent, and with a suitable design even completely or at least almost completely, converted into tensile stresses acting in a structure surrounding the press jaws, or can be absorbed or compensated by such stresses. Such tensile stresses can, in turn, be absorbed or controlled in a particularly efficient manner—with regard to the weight, volume, strength, elongation behavior, temperature coefficient, etc., of the load-bearing structure—by the annular, closed fiber structure extending around the press axis provided according to the invention.

[0006] US Patent 2006 / 0090529 A1 discloses a clamping device for a machine used for the production of metal parts in a closed mold, in which the two sub-tools of the mold are clamped against each other by means of several surrounding ring-shaped tension structures, for example, made of a carbon fiber material. US Patent 3,717,024 A discloses a press with a frame consisting of two frame elements connected to each other by bolts, wherein the two frame elements are surrounded by at least one ring-shaped closed structure made of a fiber / resin matrix.

[0007] According to the invention, the fiber structure of the radial press is part of its basic structure, which comprises at least two frame elements arranged on opposite sides of a tool installation space that accommodates the press jaws. The frame structure is open in the sense that the fiber structure forms the load-bearing connection between the two frame elements. The fiber structure connects the at least two frame elements in a manner that bridges at least one gap existing between them. The feature explained below, namely that several fiber structures are arranged offset from one another in the direction of the press axis, is particularly advantageous.In this case, if the two frame elements and the at least one fiber structure are separate components, there is particularly preferably a slippage between the at least one fiber structure and the at least two frame elements in the sense that the fiber structure can shift relative to the at least two frame elements depending on the load. In this respect, the at least one fiber structure is particularly preferably in an associated seat (or an associated guide, . e.g. arranged in the form of a guide groove), which allows the fiber structure to slip in its circumferential direction, but prevents the fiber structure from shifting transversely to the circumferential direction, i.e., in particular in the direction of the press axis.

[0008] Fiber structures in this sense are those in which long fibers extend circumferentially around the pressing axis, particularly due to (complete or at least partial) production using winding technology. Long fibers are defined as those whose length is several times the mean circumference of the ring-shaped fiber structure, resulting in a correspondingly large, i.e., multiple, wrap. Production of the fiber structure using winding technology with a continuous filament is particularly advantageous. This allows the individual fiber structures or fiber structure components to be manufactured separately, especially directly onto the component that will support them in the intended application, i.e., in situ.From an economic point of view, however, the production of longer tube-like structures (especially using the aforementioned winding technique) can also be attractive, from which the individual fiber structure components are then cut to length according to the required width.

[0009] In implementing the invention, it is significant that – during pressing of the workpiece – the fiber structure is subjected to continuous tensile stress along its entire length. In this respect, it is also essential that the fiber structure does not have excessively small radii in the circumferential direction, and certainly no kinks, corners, or edges. Rather, the outer radius of the fiber structure in the circumferential direction should at no point be less than 1.5 times the radius of the pressing tool in its fully open position. Preferably, the outer radius of the fiber structure in the circumferential direction should at no point be less than twice the radius of the pressing tool in its fully open position. However, even if – due to geometric conditions and / or particular loading situations – localized stress peaks exist within the fiber structure, the fiber orientation (as described) prevents the formation or...the propagation of a crack and thus a failure of the component.

[0010] Due to the exceptionally high strength of fiber structures, particularly carbon fibers, but also other non-metallic fiber structures (e.g., glass fibers), high-performance yet remarkably compact radial presses can be developed. This compactness is a crucial factor with regard to a wide range of applications; bulky radial presses are impractical for machining various workpiece geometries, such as tight curves.

[0011] According to a first preferred embodiment of the invention, several independent fiber structures are provided, offset from one another in the direction of the press axis. In this way, the favorable properties of the material used to produce the ring-shaped fiber structure(s) can be further utilized to optimize the dimensional accuracy and other manufacturing quality of the workpiece; because by providing several ring-shaped closed fiber structures – offset from one another in the direction of the press axis – the risk is significantly reduced that, if the workpiece is positioned differently from the ideal position along the press axis in one direction or another, the radial press will deform under load in such a way that a more or less pronounced conical pressing occurs.

[0012] According to the invention, the drive device comprises at least one drive element designed as a linear drive, which defines a working axis (extending transversely to the press axis) along which a further component of the drive device, moved by the drive element, is displaceable. The press jaws are mechanically coupled to this component in such a way that a movement of the component is converted into a radial movement of the press jaws. The at least two frame elements, around which the at least one fiber structure extends and which are connected to each other by means of the at least one annularly closed fiber structure, are held in their relative position to each other (in the direction of the working axis) by the tension acting in the fiber structure. In other words, the position of the at least two frame elements relative to each other (along the working axis) is determined in this case by the at least one fiber structure.This is preferably pre-tensioned so that a predetermined minimum tensile stress is maintained even when the drive unit is not engaged. In contrast, the at least two frame elements are preferably positioned, adjusted, and / or guided relative to each other transversely to the working axis by means of interlocking guide elements.

[0013] The design aspects described above are particularly advantageous in the radial presses mentioned here, which are built using a yoke press design, or in radial presses with a design similar to yoke presses. In these presses, two yokes (or yoke-like control bodies) are linearly movable relative to each other in a direction of movement perpendicular to the press axis, with the press jaws being housed in a tool installation space formed between the two yokes / control bodies. One of the two yokes (or one of the two control bodies) can be an integral component with a frame element of the type described above. Conversely, a drive element preferably acts on the other yoke (or the other control body), which is supported by the other, associated frame element.

[0014] It is a considerable advantage if the yokes / control bodies are supported at their edges facing away from the tool installation space by two defined support zones spaced apart from each other, each supported by an associated abutment. This counteracts the "bending" of the respective yoke / control body under load, which can sometimes be observed with full-surface support of the yoke / control body, especially with yokes / control bodies that are too small, and which has a detrimental effect on the dimensional accuracy of the workpiece. In other words, by implementing this improved design, the yokes / control bodies can be dimensioned somewhat smaller than according to the state of the art, without this having a detrimental effect on the quality of the pressing and the finished workpiece. The abutment against which the respective yoke (or control body) restsThe respective control body) is supported in the area of ​​those two spaced-apart support zones and can be an integrated part of the fiber structure, a separate frame element, or a part of the drive element.

[0015] For the sake of completeness, it should be noted that while the present invention typically provides for synchronous and consistent movement of all (e.g., eight) press jaws, this is by no means mandatory. Rather, by appropriately designing the drive unit—for example, by modifying the control surfaces of the yokes, pressure rings, or other control elements—it is possible for the press jaws to follow different movement profiles in groups, for instance, by moving some press jaws with a delay and / or slower movement and / or a reduced distance relative to the others. This can be useful in the production of special geometries.

[0016] The present invention will now be explained in more detail with reference to a preferred embodiment illustrated in the drawing. Fig. 1 shows a first embodiment of a radial press according to the present invention in a partially cutaway perspective view with the tool open; Fig. 2 shows the radial press in a partially cutaway top view. Fig. 1 and Fig. 3 a horizontal section through the radial press according to the Fig. 1 and 2 at the level of the press axis with the tool closed.

[0017] The Figures 1 to 3The radial press shown, according to a first embodiment of the invention, serves for the radial deformation of a workpiece W with respect to a press axis X. It comprises a basic structure 1 with an upper frame element 2 and a lower frame element 3. The two frame elements 2 and 3 are separate components with a parting line 4 between them. An upwardly open cylinder 7, comprising a bowl-shaped cylinder base 5 and a cylinder shell 6, is integrated into the lower frame element 3. A piston 9, integrally formed with a slide 8, is slidably guided in this cylinder along the (vertical) working axis A, providing a sealing seal. The cylinder 7 and the piston 9 define a hydraulic working chamber 10, which can be supplied with hydraulic fluid via the hydraulic connection 12 arranged at the end of a hollow piston rod 11, the bore 13 passing longitudinally through the piston rod 11 and the transverse bore 14 (opening into the working chamber 10).

[0018] The upper frame element 2 and the lower frame element 3 are adjusted and positioned relative to each other by means of guide elements 15, namely two guide tubes 16 arranged in the central plane perpendicular to the press axis X, which engage in corresponding bores 17 of the two frame elements 2, 3, and are thereby held at a predetermined distance from each other. Each of the two frame elements 2, 3 has a groove 18 on each of its two end faces, which describes a 180° arc and serves to receive a closed oval ring 19 made of carbon fibers. The two carbon fiber rings 19, which, according to the present invention, each form a fiber structure 20 extending in a ring-shaped closed form around the press axis X in a plane substantially perpendicular to the press axis X, bridge the separation joint 4 existing between the two frame elements 2, 3.They are inserted into the aforementioned grooves 18 under preload, so that the two frame elements 2, 3 maintain their relative positions, as defined by the two guide tubes 16, at least substantially, even under load (su). A minimal elongation of the carbon fiber rings 19 that occurs under particularly high pressing forces has no adverse consequences because there is slippage between the carbon fiber rings 19 and the frame elements 2, 3, allowing the tensile stresses to be distributed evenly across the carbon fiber rings 19.

[0019] Between the slide 8 – guided on the two guide tubes 16 by means of the two guide bores 21 – and the upper frame element 2, a tool installation space 23 is formed in a manner known from yoke presses (see, for example, DE 4135465 A1). This space is bounded by support and guide surfaces 22 and accommodates the press tool 25, which comprises eight press jaws 24. Since this corresponds to the well-known prior art, with the proviso that the upper frame element 2 and the slide 8 assume the function of the two yokes, reference is made to the latter; no further explanation is necessary.

[0020] The movement (arrow B) of the slide 8 along the working axis A during pressing is achieved by pressurizing the hydraulic working chamber 10 mentioned above. In this respect, the cylinder 7 and the piston 9 together constitute a drive element 26. For a rapid closing movement of the slide 8 and for opening the radial press, an additional cylinder-piston assembly 27 is provided in the form of the piston disc 28 connected to the piston rod 11, which is guided sealingly in a cylinder tube 29. This, in turn, is attached to the lower end surface of the lower frame element 3 and fixed there by means of the pressure plate 30, which is clamped against the lower frame element 3 by screws 31 and forms a cylinder base.In this way, an opening workspace 32 and a rapid closing workspace 33 are defined, wherein the opening workspace 32 can be actuated via the opening connection 34 running in the lower frame element 3 and the rapid closing workspace 33 can be actuated via the rapid closing connection 35 running in the pressure plate 30.

[0021] It is evident in the Figures 1 to 3 furthermore the worktable 36 in the form of a plate 37 connected to the slide 8, namely fixed on the upper end face of the piston 9.

Claims

1. A radial press, having an open base structure (1) comprising at least two frame elements (2, 3), a plurality of press jaws (24) arranged about a press axis (X) and a drive unit acting on these and supporting itself on the base structure (1), by means of which the press jaws (24) are radially moveable towards the press axis (X) or away from the same, wherein the radial press is embodied in the manner of a yoke press, having two yokes or control bodies (42, 46) standing in a movement direction perpendicularly to the press axis (X) that can be linearly moved relative to one another, wherein the drive device comprises at least one drive element (26) embodied as linear drive defining a work axis (A), which supports itself on one of the frame elements (2, 3), and the press jaws (24) are received in a tool installation space (23) formed between the two yokes or control bodies (42, 46), characterised, in that radially outside the press jaws (24) at least one fibre structure (20) forming a part of the base structure (1) which extends in a plane standing substantially perpendicularly on the press axis (X) and extending in an annularly closed form round about the press axis is provided which, bridging at least one separating joint (4) existing between the at least two frame elements (2, 3), interconnects these.

2. The radial press according to Claim 1, characterised, in that multiple fibre structures (20) arranged offset relative to one another in the direction of the press axis (X) are provided.

3. The radial press according to Claim 1 or Claim 2, characterised, in that the two frame elements (2, 3) are components that are separate from one another and in that there is slip between the at least one fibre structure (20) and the at least two frame elements (2, 3).

4. The radial press according to any one of the Claims 1 to 3, characterised, in that the at least two frame elements (2, 3) are secured in position relative to one another via guide elements (15) transversely to the work axis (A).

5. The radial press according to any one of the Claims 1 to 4, characterised, in that in the lower frame element (3) a cylinder (7) that is open towards the top and includes a dished cylinder base (5) and a cylinder shell (6) is integrated, in which a piston (9) moulded onto a slide (8) is displaceably guided in a sealing manner along the vertically oriented work axis (A).

6. The radial press according to Claim 5, characterised, in that the tool installation space (23) is formed between the slide (8) and the upper frame element (2), wherein the guide elements (15) are embodied as guide tubes (16) and the slide (8) is guided on the guide tubes (16).