Press element of a press, press table and press

Abstract

The invention relates to a press element of a press, in particular a press for forming sheet metal, with a damping device for compensating for dimensional fluctuations between an extended end position and a shortened end position between the press element and an additional element associated with the press element during a pressing operation along a longitudinal axis, wherein the damping device is arranged between the press element and the associated additional element during the pressing operation, wherein the damping device comprises a retaining piece, a pressure piece and a damping element, wherein the retaining piece is fixed to the press element.The pressure piece is assigned to the additional element during the pressing process, and the pressure piece is held by the retaining piece on the pressing element by means of a first limiting device, and the damping element is arranged between the pressing element and the pressure piece by means of the retaining piece with a preload applied along the longitudinal axis, and compensates for the dimensional fluctuation during the pressing process without play by means of an elastic dimensional change along the longitudinal axis, characterized in that the retaining piece has an opening extending along the longitudinal axis, wherein the pressure piece is mechanically contacted with the additional element through the opening of the retaining piece, wherein the retaining piece overlaps the pressure piece to form the first limiting device, in particular at a circumference of the opening.

Description

[0001] The invention relates to a press element of a press, in particular a press for forming sheet metal, with a damping device for compensating for dimensional fluctuations between an extended end position and a shortened end position between the press element and an additional element associated with the press element during a pressing operation along a longitudinal axis, wherein the damping device is arranged between the press element and the associated additional element during the pressing operation, wherein the damping device comprises a retaining piece, a pressure piece and a damping element, wherein the retaining piece is fixed to the press element.that the pressure piece is assigned to the additional element during the pressing process and the pressure piece is held by the retaining piece on the press element by means of a first limiting device, and the damping element is arranged between the press element and the pressure piece by means of the retaining piece with a preload applied along the longitudinal axis and compensates for the dimensional fluctuations during the pressing process without play by means of an elastic dimensional change along the longitudinal axis. Furthermore, the invention relates to a press table with one or more press elements of the aforementioned type, as well as a press with one or more press elements of the aforementioned type or a press table according to the aforementioned embodiment.

[0002] Presses, especially presses for forming sheet metal, often have additional elements, such as press bolts or holding dies, for holding or guiding a sheet metal part. These additional elements, particularly the press bolts, are subject to dimensional variations. Such dimensional variations can arise from temperature fluctuations as well as manufacturing tolerances. With such additional elements of varying length, a sheet metal part is held and deformed or held unevenly, for example, only insecurely or unevenly. To address this problem, various damping devices are known. For example, hydraulic damping devices are known in which hydraulic compensation takes place between different additional elements, such as different press dies.

[0003] Adjustable additional elements, for example by means of threads, are also known. A corresponding arrangement is disclosed in DE 10 2014 004 521 B4. .

[0004] Furthermore, active adjustment mechanisms, for example for pressure bolts or pressure stamps, are known. DE 10 2017 214 660 A1 is mentioned in this context.

[0005] DE 10 2017 206 753 A1 discloses a device and a method for adjusting the compensating discs of a drawing cushion device. Several height-direction positions of several drawing pins can be adjusted using several hydraulic cylinders. It is also disclosed how individual positions of the hydraulic cylinders can be stored for subsequent adjustments.

[0006] DE 103 53 350 A1 concerns details of a press. Spring pins for a press are supported by an elastic element, such as disc springs, so that the load on individual spring pins during a pressing process is balanced.

[0007] US 2008 / 016929 A1, which forms the basis for the preamble of claim 1, discloses a press element of a press with a damping device for compensating for a dimensional variation between an extended end position and a shortened end position between the press element and an additional element associated with the press element during a pressing operation along a longitudinal axis, wherein the damping device is arranged between the press element and the associated additional element during the pressing operation, and wherein the damping device comprises a retaining piece, a pressure piece and a damping element.

[0008] All of the aforementioned arrangements have in common that they are very elaborate and / or technically complicated.

[0009] The object of the invention is to improve the state of the art.

[0010] The problem is solved by a press element of a press, in particular a press for forming sheet metal, with a damping device for compensating for a dimensional variation between an extended end position and a shortened end position between the press element and an additional element assigned to the press element during a pressing operation along a longitudinal axis, wherein the damping device is arranged between the press element and the assigned additional element during the pressing operation, wherein the damping device comprises a retaining piece, a pressure piece and a damping element, wherein the retaining piece is fixed to the press element.that the pressure piece is assigned to the auxiliary element during the pressing process and the pressure piece is held by the retaining piece on the pressing element by means of a first limiting device, and the damping element is arranged between the pressing element and the pressure piece by means of the retaining piece with a preload applied along the longitudinal axis and compensates for dimensional fluctuations during the pressing process without play by means of an elastic dimensional change along the longitudinal axis. In addition, the retaining piece has an opening extending along the longitudinal axis, wherein the pressure piece is mechanically contacted with the auxiliary element through the opening of the retaining piece, wherein the retaining piece overlaps the pressure piece at one circumference of the opening to form the first limiting device.

[0011] Such a press element with a damping device is simple in design, requires no electrical or hydraulic components, and is also easy to maintain. Preload allows for backlash-free compensation of dimensional variations, utilizing the elastic dimensional change of the damping element, thus eliminating the need for additional mechanical components or complex technical arrangements. Furthermore, the preload force can be adjusted, enabling the damping device to be selected and designed according to the intended application. Overall, this allows for a compact design of both the press element and the damping device.

[0012] In this context, the following terms should be explained: A "press element" of a press is, for example, a fixed component or a part of a movable component of a press, whereby the damping device may be connected to this press element. It is irrelevant whether the press element is located on a fixed or a movable side of the press. In principle, any component of a press can be such a press element. In particular, such a press element is a mechanical component of the press that serves, for example, to absorb or transmit a force, such as a press ram, a press bolt, a pressure plate of a drawing device, or a press table.

[0013] A "press" is a machine tool used for forming materials. Such a press can be either hydraulically operated or force-operated. In a press, a ram, which serves as the movable part of the press, typically acts on a press table. The force exerted between the ram and the press table is then used, for example, to form sheet metal. In this context, a "ram" refers to the movable working element of the press, such as a hydraulic cylinder or the mechanically active part of a crank mechanism that performs the pressing operation. A "pin" is usually an elongated, rod-shaped component of a press and is used, for example, during the pressing of sheet metal to temporarily hold sections of the sheet metal in place during the pressing process, thus controlling the forming process.A press can, in particular, have several press bolts, for example around the circumference of the sheet metal to be processed.

[0014] In this context, "sheet metal forming" refers, for example, to deep drawing, compression forming, or contour forming of sheet metal, particularly metal or steel. Such sheet metal forming can be used, for instance, to create the shape of a car door or other body parts.

[0015] In this context, a "damping device" describes, for example, a part of the press element that directly serves to compensate for dimensional variations and, in addition to compensating for these variations, can also provide mechanical damping, such as reducing vibrations. Such a damping device can, for example, be a compensating element for dimensional variations.

[0016] A "dimensional variation" between an extended end position and a shortened end position describes, for example, the thermal elongation of a press bolt, a manufacturing-related shortening of such a press bolt, or any other compression, elongation, or shortening of corresponding press components. Likewise, such a dimensional variation can be caused not only by a press bolt, but also by, for example, the press table, a press ram, another fixture, or other components. The dimensional variation relates in particular to the desired achievable precision of the component, for example, the sheet metal being processed, which is to undergo forming.

[0017] An "extended end position" describes the largest possible dimensional variation that can still be compensated for by the damping device, whereas the "shortened end position" describes the smallest possible position of the damping device to compensate for corresponding dimensional variations.

[0018] A "limiting device" is used to restrict the movement of a pressure piece. Such a limiting device acts mechanically on the pressure piece and limits its path of movement.

[0019] An "additional element" is, for example, a press bolt or another component of the press, whereby with regard to dimensional variation, it is irrelevant whether this variation is triggered or caused by the press element, the additional element, or another component of the press. In connection with the present invention, the additional element is generally a movable or replaceable element, wherein the press element is, for example, fixedly connected to the press.

[0020] With regard to the damping device and dimensional variation, the "longitudinal axis" describes the direction along which the dimensional variation is to be compensated. Such a longitudinal axis is not mathematically precisely defined. Deviations that are technically necessary, for example from +10° to -10° relative to a full 360° angle, must be taken into account.

[0021] A "retaining piece" is the component that is fixed to the press element and holds the pressure piece, and thus the damping element, to the press element. Such a retaining piece can be, for example, a mechanical clamp, a positive-locking component, a friction-locking component, or another type of component that can hold the pressure piece, and thus the damping element, to the press element. In this context, a "pressure piece" serves to transfer forces applied by the auxiliary element to the damping element. Furthermore, the pressure piece acts as wear protection for the damping element.

[0022] A "damping element" is a component that compensates for dimensional fluctuations through elastic dimensional changes along its longitudinal axis. For example, such a damping element is an elastic component that generates or absorbs forces depending on the path length.

[0023] A "preload" describes the state in which the damping element is subject to compressive stress, specifically in the assembled, resting state of the press element and / or damping device. This compensates for tolerances, allows for adjustable preload force, and enables backlash-free pressing. The preload is primarily determined by the dimensions of the damping element and other components, and is adjusted accordingly.

[0024] In order to form a clearly defined end stop, the holding piece limits the pressure piece along the longitudinal axis by means of the first limiting device in a form-fitting manner in the direction of the extended end position relative to the press element, so that a positive end stop is formed for the pressure piece in the direction of the extended end position.

[0025] A mechanically defined positive end stop is formed by a "form-fit" receiving action, which achieves a corresponding limitation through two opposing geometries.

[0026] Such a "positive end stop" is a travel limit in the direction of the extended end position, i.e. along the longitudinal axis up to the extended end position, so that the pressure piece cannot be moved further towards the extended end position beyond this positive end stop.

[0027] In one embodiment, the press element limits the pressure piece along the longitudinal axis by means of a second limiting device in a form-fitting manner in the direction of the shortened end position relative to the first press element, so that a negative end stop is formed for the pressure piece in the direction of the shortened end position, wherein in particular the press element receives a pressure surface of the pressure piece in a form-fitting manner to form the second limiting device of a contact surface.

[0028] Thus, a defined, positive-locking end stop is also formed in the direction of the shortened end position, so that the travel of the damping element is clearly limited. If the pressure piece has a pressure surface, this can be received by the pressing element over a flat area and thus positively locked, specifically at a contact surface.

[0029] A "pressure surface" is, for example, a flat surface of the printing piece which runs parallel to a surface of the press element, whereas the "contact surface" is a corresponding surface on the press element.

[0030] An "opening," which can also be called a "breakthrough" or "bore," is a recess of material within the retaining piece through which the pressure piece can pass and act on the additional element and / or interact with it. The pressure piece and the additional element are mechanically contacted through this opening.

[0031] In one embodiment, the first limiting device is designed as a concentrically arranged shoulder opposite a corresponding, concentrically arranged shoulder on the pressure piece.

[0032] This allows, for example, the use of a rotationally symmetrical pressure piece, with a corresponding retaining piece also being designed to be rotationally symmetrical. This enables some or even all components, including the damping element, to be designed with rotational symmetry and arranged concentrically, with a central axis aligned with the longitudinal axis. This allows the press element and the corresponding damping device to be manufactured in a particularly compact form.

[0033] To make the press element, and in particular the damping device, easier to maintain, the retaining piece is detachably connected to the press element. This allows the damping element to be replaced between the retaining piece and the press element, with the retaining piece being able to be fixed to the press element, in particular by means of screws.

[0034] In the simplest case, the retaining piece can be removed from the press element by loosening the screws, so that the damping element and / or a corresponding pressure piece can be removed and replaced.

[0035] "Interchangeable" describes precisely this possibility of exchanging different components of the press element and / or removing and replacing corresponding components of the press element.

[0036] In one embodiment, the pressure piece has a centering means for the damping element, so that the damping element can be fixed radially relative to the pressure piece by the centering means in a centering receptacle corresponding to the centering means.

[0037] The centering receptacle, in conjunction with the centering device, ensures that the damping element is securely and reliably mounted, particularly in the described concentric arrangement of components. For example, the damping element can have the shape of a so-called donut, i.e., a round, disc-shaped form with a concentric hole in the center.

[0038] In this context, a "centering means" is, for example, a particularly concentric geometric shape on the pressure piece, which interacts with a corresponding "centering receptacle", i.e., a corresponding inverse geometry, in order to fix the damping element radially relative to the pressure piece.

[0039] In order to effectively adapt the damping element to the high forces of a pressing process, the damping element comprises an elastomer, in particular a PU (polyurethane) and / or a spring, in particular a disc spring or several disc springs.

[0040] An "elastomer" is a dimensionally stable but elastically deformable plastic whose glass transition temperature is below its service temperature. Such a plastic can deform elastically under tensile and compressive stress, but then returns to its original, undeformed shape. During this elastic deformation, forces are absorbed or exerted on a component acting upon the elastomer, depending on the displacement. Examples of such elastomers include rubber, caoutchouc, and silicone rubber.

[0041] A "spring" is a component, usually made of metal, that can deform elastically and thus, similar to an elastomer, absorb and return corresponding forces. A "disc spring" is a special case of a spring, where a disc spring can absorb elastic forces through the buckling deformation of a flat spring element, which is assembled in a ring shape.

[0042] In another aspect, the problem is solved by a press table with one or more press elements according to one of the previously described embodiments, wherein the press element is connected to the press table or is formed by the press table.

[0043] According to this aspect, for example, by joining multiple press elements on a press table, or by forming the press element with the press table using a variety of retaining elements and a variety of pressure pieces and damping elements, a press table that can be variably adapted to corresponding dimensional variations can be created. For example, such a press table can also be replaced as a fully prepared component when corresponding damping elements or pressure pieces are worn.

[0044] In another aspect, the problem is solved by a press with one or more press elements according to one of the previously described embodiments or a press table according to the previously described type and in particular an additional element associated with the press element.

[0045] The invention will now be explained in more detail using exemplary embodiments. These will show... Figure 1 is a schematic representation of a press table with a multitude of compensating devices in an isometric view; Figure 2 is a cutaway detail view of a compensating device on the press table. Figure 1 Figure 3 shows a top view of a compensating element of the Figure 2 , as well as Figure 4, a damping element of the compensating element of the Figures 2 and 3 .

[0046] A press table 101 with a base 103 is mounted on feet 108. The press table 101 is part of a press for forming sheet metal; other components such as the press frame and the press ram are not shown for the sake of simplicity. The press table 101 serves as part of a lower tool or as a holder for a lower tool for forming sheet metal.

[0047] A removable plate 105 is attached to the upper side of the base frame 103 by means of screw anchors 107. The removable plate 105 carries a plurality of compensating elements 201 in a matrix-like arrangement along axes 131 and 133 that are arranged orthogonally to each other. By means of several lifting eyes 109, the removable plate 105 can be completely removed from the base frame 103 after loosening the screw anchors 107 and, for example, replaced when the corresponding compensating elements 201 are worn or need to be replaced with compensating elements of a different design.

[0048] Each compensating element 201 has a retaining piece 203, which has a round and concentrically arranged opening 205. Furthermore, a stop ring 207 is formed concentrically to the opening 205 by means of a shoulder directed towards the interchangeable plate 105. The retaining piece 203 is fastened to the interchangeable plate 105 by means of screws 211, which are guided through bores 213. The heads of the screws 211 are received in pockets 215 so that the screws do not protrude beyond the contours of the retaining piece 203. The outer contour of the retaining piece 203 is square, with corresponding screws 211 arranged at each corner of the square.

[0049] The opening 205 and the stop ring 207 are arranged concentrically to a longitudinal axis 231, the longitudinal axis 231 being located centrally within the square base of the retaining piece 203. The longitudinal axis 231 is perpendicular to the changeover plate 105. A closing direction of the press (not shown) also runs along this longitudinal axis 231, in which the press table 101 is arranged as described above.

[0050] A pressure piece 301 is arranged in the opening 205. The pressure piece 301 is round and arranged in the opening 205 parallel to the longitudinal axis 231 along a possible direction of movement. The pressure piece is shaped such that it extends through the opening 205 and thus forms a punch surface 303 pointing away from the indexable plate 105. The punch surface 303 is arranged such that the longitudinal axis 231 runs parallel to the normal of the punch surface 303 and the punch surface 303 is substantially parallel to the surface of the indexable plate 105. During a pressing operation, the punch surface 303 receives a respective press bolt (not shown), which is, for example, a respective movable component of a lower tool.

[0051] A damping element 401 is pre-tensioned between the pressure piece 301 and the changeable plate 105. The dimensions of the retaining piece 203, the position of the stop ring 207, the position of a stop ring 305 acting against the stop ring 207 on the pressure piece 301, and the height of the damping element 401 along the longitudinal axis 231 are dimensioned such that the damping element receives the desired pre-tension. The damping element 401 is made of an elastomer and is ring-shaped.

[0052] A centering pin 307, extending from the pressure piece along the longitudinal axis 231 towards the interchangeable plate 105, engages through a centrally located hole in the damping element 401 and rests against an inner surface 405. An outer surface 403 of the damping element 401 is positioned at a distance from the retaining piece 203, allowing the damping element 401 to expand. The pressure piece 301 also has a stop surface 309 facing the interchangeable plate 105, which is aligned with a contact surface 106 of the interchangeable plate 105. In the unloaded state, there is a gap between the contact surface 106 and the stop surface 309.

[0053] The function of the compensating element 201 in connection with the press and a pressing process is described as follows:

[0054] When pressure is applied to the press by means of an upper tool (not shown), corresponding press bolts (not shown) are also subjected to stress by a sheet metal plate (not shown) located between the upper and lower tools. It is assumed here that the pressure bolts exhibit length variations along the longitudinal axis 231. The upper end position of the corresponding pressure piece 301 is defined by the contact of the stop ring 207 with the stop ring 305 of the pressure piece 301.

[0055] The pressure piece 301 is held in this position by the preload of the damping element 401. The preload is matched to the desired pressure of the press bolt on, for example, a machined sheet metal part. If the press bolt is longer than originally specified, the pressure piece 301 will slide in the opening 205 of the retaining piece 203 towards the changeable plate 105, thereby compressing the damping element 401. The corresponding increase in force on the press bolt is determined by the hardness of the damping element 401. The damping element then expands radially, with the outer surface 403 pressing towards the retaining piece 203, but still able to expand. The damping element 401 can also expand elastically inwards. Once a desired end stop is reached, the stop surface 309 of the pressure piece 301 runs onto the contact surface 106 of the changeable plate 105.At this point, the travel of the pressure piece 301 is limited, so no further compensation occurs. The permissible travel of the pressure piece 301 within the retaining piece 203 is matched to the tolerance of, for example, the length of the respective press bolt.

[0056] If a damping element 401 on the interchangeable plate 105 or a pressure piece 301 is worn, individual compensating elements 201 can be easily replaced by loosening the screws 211 and removing the retaining piece 203. Alternatively, the interchangeable plate 105 can be removed after loosening the screw anchors 107 and replaced, for example, with another interchangeable plate with completely renewed compensating elements 201. Reference symbol list

[0057] 101 Press table 103 Base frame 105 Interchangeable plate 106 Contact surface 107 Screw anchor 108 Foot 109 Lifting eye 131 Axis 133 Axis 201 Compensating element 203 Retaining piece 205 Opening 207 Stop ring 211 Screw 213 Bore 215 Pocket 231 Longitudinal axis 301 Pressure piece 303 Punch surface 305 Stop ring 307 Centering pin 309 Stop surface 401 Damping element 403 Outer surface 405 Inner surface

Claims

1. Press element (105) of a press, in particular a press for shaping sheet metal, comprising a damping device (201) for compensating for a fluctuation in dimensions between an elongated end position and a shortened end position between the press element (105) and an additional element assigned to the press element (105) during the pressing process along a longitudinal axis (231), wherein the damping device (201) is arranged between the press element (105) and the assigned additional element during the pressing process, wherein the damping device (201) comprises a holding piece (203), a pressure piece (301) and a damping element (401), wherein the holding piece (203) is fixed to the press element (105), the pressure piece (301) is assigned to the additional element during the pressing process and the pressure piece (301) is held on the press element (105) by the holding piece (203) by means of a first delimiting device (207), and the damping element (401) is arranged to have pre-loading between the press element (105) and the pressure piece (301) applied along the longitudinal axis (231) by means of the holding piece (203) and compensates for the fluctuation in dimensions during the pressing process without play owing to a resilient change in dimensions along the longitudinal axis (231), characterised in that the holding piece (203) comprises an opening (205) extending along the longitudinal axis (231), wherein the pressure piece (301) is mechanically contacted by the additional element through the opening (205) in the holding piece (203), wherein the holding piece (203) engages over the pressure piece (301) on a circumference of the opening (205) to form the first delimiting device (207).

2. Press element according to claim 1, characterised in that the holding piece (203) delimits the pressure piece (301) relative to the press element (105) in the direction of the elongated end position in a form-fitting manner along the longitudinal axis (231) by means of the first delimiting device (207), such that a positive end stop (305) is formed for the pressure piece (301) in the direction of the elongated end position.

3. Press element according to claim 1 or 2, characterised in that the press element (105) delimits the pressure piece (301) relative to the press element (105) in the direction of the shortened end position in a form-fitting manner along the longitudinal axis (231) by means of a second delimiting device (106), such that a negative end stop (309) is formed for the pressure piece (301) in the direction of the shortened end position, wherein, in particular, the press element (105) receives a pressure surface (309) of the pressure piece (301) in a form-fitting manner to form the second delimiting device on a contact surface (106).

4. Press element according to any of the preceding claims, characterised in that the first delimiting device (207) is designed as a concentrically arranged shoulder (207) facing a corresponding concentrically arranged shoulder (305) on the pressure piece (301).

5. Press element according to any of the preceding claims, characterised in that the holding piece (203) is detachably connected to the press element (105) such that the damping element (401) is interchangeably received between the holding piece (203) and the press element (105), wherein the holding piece (203) can in particular be fixed to the press element (105) by means of screws (211).

6. Press element according to any of the preceding claims, characterised in that the pressure piece (301) comprises a centring means (307) for the damping element (401), such that the damping element (401) can be fixed radially relative to the pressure piece (301) by the centring means (307) in a centring receptacle (405) corresponding to the centring means (307).

7. Press element according to any of the preceding claims, characterised in that the damping element (401) comprises an elastomer, in particular a polyurethane and / or a spring, in particular a spiral spring or a plurality of spiral springs.

8. Bolster plate comprising a press element (105) or comprising a plurality of press elements according to any of claims 1 to 7, characterised in that the press element (105) is connected to the bolster plate or is formed by the bolster plate (105).

9. Press comprising a press element (105) or a plurality of press elements according to any of claims 1 to 7 or a bolster plate (105) according to claim 8 and in particular an additional element assigned to the press element.

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