Pressing device

Abstract

Pressing device (100) for radially pressing workpieces, comprising: - a pressing ring (PR) which encloses a pressing chamber (R) and includes at least one lever arm (HA, 110); - at least one pressing jaw (PB, 120) which is movably mounted on the inside of the lever arm (HA, 110); characterized in that the pressing jaw (PB, 120) and the lever arm (HA, 110) are in force-transmitting contact at two separate contact surfaces, wherein the pressing jaw (PB, 120) and the lever arm (HA, 110) are in force-transmitting contact via at least one sliding shoe (GS, 122) and an associated sliding surface (GF, 111, 112, 113).

Description

The invention relates to a pressing device for radially pressing workpieces, in particular pipes or fittings for pipes. From DE 20 2010 000 402 U1, a pressing device for radially pressing pipes is known, which includes a pressing ring formed by two lever arms, wherein pressing jaws with correspondingly shaped sliding surfaces are movably arranged on sliding surfaces on the inside of the lever arms. When the pressing ring is tightened by means of a pressing tool, the pressing jaws are pressed radially inwards, moving along the sliding surfaces. CN 2 08 262 231 U discloses a pressing device in which two U-shaped pressing jaws each bear against lever arm surfaces on the front and rear of the pressing device, respectively. CN 2 14 639 717 U discloses a mirror-image design in which the lever arms have U-shaped contours that bear against corresponding surfaces of the three pressing jaws on the front and rear of the pressing device. Furthermore, KR 10 1 598 204 B1 discloses a pressing device in which rolling bearings with round rollers are formed between the lever arms and the pressing jaws. A problem with known pressing devices is that their function can be impaired by contamination. Against this background, the objective of the present invention was to provide a pressing device with high functional reliability. This problem is solved by a pressing device with the features of claims 1 and 2. Advantageous embodiments are included in the dependent claims. The pressing devices according to the present invention are used for pressing workpieces such as pipes or fittings and comprise the following components as a basic structure: - A pressing ring that encloses a pressing chamber and contains at least one lever arm. - At least one pressing jaw, which is movably mounted on the inside of the lever arm. The press ring can optionally be formed from two or more lever arms, which are articulated together in a row. Additionally or alternatively, the press ring can also contain other flexible elements, such as a tension band. When using the press, the workpiece is positioned within the press chamber enclosed by the press ring. The pressing action then occurs through a narrowing of the press ring, with the necessary (high) forces typically applied by an external press tool. The press jaw is generally the component that comes into direct contact with the workpiece and therefore typically has a section with a contour shaped to match the workpiece. Usually, two, three, four, or more press jaws are mounted on the press ring. When the press ring narrows, the press jaws are pressed radially inward, thereby creating the desired compression of the workpiece. Due to their mobility relative to the press ring, they can assume the most symmetrical and optimal position possible during this process. It is also possible for a lever arm to be in contact with two or more pressing jaws. Conversely, a pressing jaw can optionally be in contact with two or more lever arms. In these cases, when referring to "the pressing jaw and the (associated) lever arm," all these lever arms and pressing jaws are always meant. The basic structure of a pressing device described above is further developed according to a first aspect of the invention in that the at least one pressing jaw and the at least one lever arm are in force-transmitting contact at (at least) two separate contact surfaces. A "contact surface" is, by definition, the surface on which the pressing jaw and the lever arm are in contact and is jointly formed by contact areas on these components. The pressing device is further designed such that the pressing jaw and the lever arm are in force-transmitting contact via at least one sliding shoe and at least one associated sliding surface. The sliding shoe provides at least one of the (at least) two separate contact surfaces between the pressing jaw and the lever arm. Unlike a pressing device such as that described in DE 20 2010 000 402 U1, there is no single continuous surface where the pressing jaw and the associated lever arm are in contact. Instead, there are two (or more) surface areas with zones between them where there is no contact between the pressing jaw and the lever arm. The fact that these contact surfaces are intended to be "force-transmitting" in this context means that, when the pressing ring narrows, they transmit the radially inward-directed compressive forces to the pressing jaws, which ultimately lead to the pressing of the workpiece. Contacts between the pressing jaw and the pressing ring that do not (or cannot) transmit such compressive forces, on the other hand, do not constitute the "force-transmitting" contact surfaces referred to here.In a preferred embodiment, the at least one press jaw and the at least one lever arm are in force-transmitting contact at four contact surfaces, which, for example, form two symmetrically arranged pairs of contact surfaces. According to a second aspect of the invention, a pressing device with the basic structure described above is further developed in such a way that the pressing jaw and the lever arm are in force-transmitting contact via at least one sliding shoe, wherein the sliding shoe is movably mounted on the pressing jaw or on the lever arm. Due to its movable mounting, the sliding shoe can move relative to the press jaw and the lever arm during a pressing operation. This makes the contact surface with the lever arm and the press jaw movable, thus providing an additional degree of freedom for controlling the movement of the press jaw, which allows the pressing operation to be carried out as symmetrically as possible. Preferably, the sliding shoe is mounted to allow rotation. A pressing device according to the embodiments described above can optionally be further developed in such a way that the entire force-transmitting contact area between the pressing jaw and the lever arm is less than 200 mm2, preferably less than 100 mm2, particularly preferably less than 50 mm2. Preferably, the pressing device is designed according to both aspects, i.e., it contains at least two separate force-transmitting contact surfaces and a movably mounted sliding shoe between a pressing jaw and the associated lever arm. In the pressing devices described above, the contact between the pressing jaw and the lever arm no longer occurs inflexibly over a large area, but rather over a smaller area, which can optionally be subdivided into several unconnected parts and / or be movable. This has the advantage of providing more space within the pressing device in which dirt particles and the like can accumulate without impairing the device's function. In particular, the risk of these particles affecting the contact areas between the pressing jaw and the lever arm is reduced. Furthermore, the increased surface pressure results in a self-cleaning effect on the contact areas. Additionally, the presence of multiple contact surfaces and / or movable contact surfaces allows for better predictability of the pressing jaw's movement during the pressing process. According to the invention, the press jaw and the lever arm are in force-transmitting contact via at least one sliding shoe and at least one associated sliding surface. By definition, the sliding shoe can move along the sliding surface. The force transmission thus typically always occurs via the same area of ​​the sliding shoe, but via varying sections of the sliding surface. As in the second aspect explained above, the sliding shoe can be movably mounted or rigidly connected to the press jaw or the lever arm. The aforementioned sliding shoe can be located on the press jaw, and the sliding surface on the lever arm. The reverse arrangement is also possible; in the case of multiple sliding shoes / sliding surfaces, some can be located on the press jaw and others on the lever arm, or all can be located on the press jaw or the lever arm. The sliding shoe and / or the sliding surface can be integrally formed with the associated component (press jaw or lever arm). Preferably, however, the sliding shoe is a separate component. This has the advantage that it can be designed independently of the rest of the component (e.g., the press jaw) with regard to material and shape. The sliding shoe can also optionally be replaceable, so that it can be renewed if necessary. As already mentioned, the sliding shoe can also be movably mounted on the associated component (press jaw or lever arm), in particular rotatably about an axis parallel to the axis of the press ring. According to a further embodiment of the invention, the press jaw and the lever arm are in contact via (at least or exactly) two sliding shoes and at least one associated sliding surface. Preferably, the sliding shoes are formed on the same component (the press jaw or the lever arm). Using two sliding shoes makes it possible to control the movement of the press jaw very precisely during the pressing process and, for example, to also influence rotational movements of the press jaw. The combination of two sliding shoes with an associated sliding surface can also be provided multiple times on the same press jaw and the same lever arm, in particular once on the front and once on the back of the pressing device. In a further development of the embodiment described above, the press jaw and the lever arm are in contact with each other via two sliding shoes and two associated sliding surfaces inclined at different angles. "Sliding surfaces inclined at different angles" means that the main directions of travel of the sliding surfaces form an angle with each other (typically the sliding surfaces are flat, so their main direction of travel is defined by the direction of the plane; for curved sliding surfaces, a suitable average value must be calculated). During the pressing process, the sliding shoes are therefore guided along different paths, allowing their movement to be controlled very precisely. The combination of two sliding shoes with two associated sliding surfaces inclined at different angles can again be provided multiple times on the same press jaw and the same lever arm, in particular once on the front and once on the back of the pressing device. In the embodiments described above, the inclination of the sliding surfaces can be designed such that, in the event of a radial narrowing of the pressing ring, the pressing jaw is displaced radially inwards as uniformly as possible (for example, purely translationally along a straight line). This allows for a good pressing result without creating significant irregularities (steps, etc.) on the workpiece. At least one contact area on the press jaw and / or the lever arm, which is involved in forming the force-transmitting contact surface between the press jaw and the lever arm during the pressing process, is advantageously hardened. This ensures sufficient stability even at high pressing pressures and minimizes wear. The invention will now be explained in more detail with reference to an exemplary embodiment and the figures. Figure 1 shows a section through a pressing device according to the invention above the pressing jaws; Figure 2 shows a section analogous to Figure 1 in the plane of the pressing jaws; Figure 3 shows an exploded view of the pressing device, with non-essential components omitted for clarity; Figure 4 shows the exploded view of Figure 3 with all components. The pressing device 100 shown in the figures serves in a known manner to press a workpiece such as a pipe or a fitting by means of a radially inward directed pressure. The pressing device 100 has an approximately cylindrical pressing chamber R in which the workpiece to be processed can be arranged. The pressing chamber is enclosed by a pressing ring PR, which in the illustrated embodiment is formed from two mirror-image lever arms 110 (or generally, in reference letters: HA) arranged and shaped in a pivot joint. These lever arms are movably connected to each other at one end via a tab 114. The free ends of the lever arms have attachment points (below in Fig. 1) for a pressing jaw (not shown), by which they can be pressed together with high force. During this pressing process, the radius enclosed by the pressing ring PR decreases, resulting in the compression of the pipe. The pressing device also includes pressing jaws 120 (or PB), which are movably mounted on the inside of the pressing ring PR (or its lever arms HA) and define the pressing chamber R on the inside. Each pressing jaw PB consists of the actual pressing jaw body 121 and two sets of two sliding shoes 122 (or GS) per pressing jaw. During the pressing process, circular segment-shaped contours of the pressing jaws PB come into contact with the workpiece and cause it to be compressed. In the illustrated embodiment, two lever arms HA are provided, and four press jaws PB are arranged symmetrically on them, with two jaws mounted on each lever arm. However, other numbers and / or arrangements of these components are also possible. When the press ring PR is contracted, the press jaws PB are moved radially inwards, shifting relative to the lever arms according to the forces acting upon them. This is made possible by a movable bearing relative to the lever arms. This bearing is achieved in particular via force-transmitting contact surfaces between the press jaws PB and their respective associated lever arms HA. In the illustrated embodiment, the contact surfaces are formed by the sliding shoes GS, which are an integral part of the press jaws PB, and by sliding surfaces 111, 112, 113 (or generally GF) formed on the inner sides of the lever arms HA. Four sliding shoes GS are provided for each press jaw PB, sliding along their associated sliding surfaces GF, and arranged in two pairs symmetrically to the central plane of the press (plane of drawing in Fig. 1). In particular, in the exemplary embodiment, the arrangement is such that the sliding shoes GS of the press jaws PB located at the open end of the press ring PR (bottom in Fig. 1) slide on two differently inclined (planar) sliding surfaces 111 and 112. The sliding shoes GS of the press jaws PB located at the hinge tab 114 (top in Fig. 1), on the other hand, slide on the same (planar) sliding surface 113. This design of the sliding surfaces and the angles of inclination of the differently inclined sliding surfaces 111 and 112 ensure that all four press jaws move radially inwards as uniformly as possible during the pressing process. In the closed state of the press device, the sliding surfaces 111 and 112 preferably form an angle of approximately 45° (distal sliding surface 111), approximately 25° (middle sliding surface 112) and approximately -45° (proximal sliding surface 113) with the axis of symmetry of the press device (vertical V in Fig. 1). The cross-section in Fig. 2 shows that the press jaws PB are each additionally mounted on the associated lever arms HA via springs 115, with the springs pressing opposing press jaws towards each other. The spring action supports the desired uniform inward movement of the press jaws. The exploded views in Figures 3 and 4 show that the sliding shoes GS provided on the press jaws are not integrally connected to the press jaw bodies 121. Rather, they are separate components that were subsequently inserted into pockets in the press jaw bodies 121. The sliding shoes GS are essentially cylindrical with a flattened side that forms the sliding contact area. They can be made of a hardened material such as stainless steel. Furthermore, the sliding shoes are preferably rotatably mounted in the pockets on the press jaw bodies 121. In the illustrated example, they are rotatable about an axis parallel to the axis of the press ring PR (i.e., an axis perpendicular to the plane of Figure 1). The rotatable design allows the sliding shoes to move along with the pressing process (typically by approximately 1° to 5°). This further supports a uniform radial inward movement of the pressing jaws.

Claims

Pressing device (100) for radially pressing workpieces, comprising: - a pressing ring (PR) which encloses a pressing chamber (R) and includes at least one lever arm (HA, 110); - at least one pressing jaw (PB, 120) which is movably mounted on the inside of the lever arm (HA, 110); characterized in that the pressing jaw (PB, 120) and the lever arm (HA, 110) are in force-transmitting contact at two separate contact surfaces, wherein the pressing jaw (PB, 120) and the lever arm (HA, 110) are in force-transmitting contact via at least one sliding shoe (GS, 122) and an associated sliding surface (GF, 111, 112, 113). Pressing device (100) for radially pressing workpieces, in particular according to claim 1, comprising: - a pressing ring (PR) enclosing a pressing chamber (R) and containing at least one lever arm (HA, 110); - at least one pressing jaw (PB, 120) which is movably mounted on the inside of the lever arm (HA, 110); characterized in that the pressing jaw (PB, 120) and the lever arm (HA, 110) are in force-transmitting contact via at least one sliding shoe (GS, 122), wherein the sliding shoe (GS, 122) is movably mounted on the pressing jaw (PB, 120) or on the lever arm (HA, 110). Pressing device (100) according to claim 1 and / or 2, characterized in that the total force-transmitting contact area between the press jaw (PB, 120) and the lever arm (HA, 110) is less than 200 mm2. Pressing device (100) according to at least one of the preceding claims, characterized in that the press jaw (PB, 120) and the lever arm (HA, 110) are in force-transmitting contact via at least one sliding shoe (GS, 122) which is immovably connected to the press jaw (PB, 120) or the lever arm (HA, 110), and an associated sliding surface (GF, 111, 112, 113). Pressing device (100) according to at least one of claims 1 to 4, characterized in that the sliding shoe (GS, 122) is formed on a press jaw (PB, 120) and the sliding surface (GF, 111, 112, 113) is formed on the lever arm (HA, 110). Pressing device (100) according to at least one of claims 1 to 5, characterized in that the press jaw (PB, 120) and the lever arm (HA, 110) are in contact via two sliding shoes (GS, 122) and at least one associated sliding surface (GF, 111, 112, 113). Pressing device (100) according to claim 6, characterized in that the pressing jaw (PB, 120) and the lever arm (HA, 110) are in contact via two sliding shoes (GS, 122) and two associated, differently inclined sliding surfaces (GF, 111, 112). Pressing device (100) according to claim 7, characterized in that the inclination of the sliding surfaces (GF, 111, 112) is designed such that the press jaw (PB, 120) is displaced uniformly radially inwards during the pressing process. Pressing device (100) according to claim 2, characterized in that the sliding shoe (GS, 122) is mounted to be rotatable. Pressing device (100) according to at least one of the preceding claims, characterized in that at least one contact area forming the force-transmitting contact surface between the press jaw (PB, 120) and the lever arm (HA, 110) is hardened on the press jaw and / or the lever arm.

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