locking press

Abstract

A clamping press (1, 1') having a longitudinal direction (L) and a width direction (B) extending at right angles thereto, wherein the clamping press (1, 1') has a press table (2), a press ram (3) arranged above the press table (2), several press cylinders (4) arranged below the press table (2), and several tension yokes (5), wherein the tension yokes (5) each have a closed yoke frame (51), a yoke head (52) having an inner support (53), and a yoke foot (54) pivotably attached to a joint (6) of the clamping press (1, 1'), characterized in that the press cylinders (4) are arranged below opposite edge regions of the press table (2), the clamping press (1, 1') is arranged below two opposite press cylinders (4), rotatably mounted crossbeams extending in the width direction (B) of the clamping press (1, 1') (7),wherein a tilting mechanism (8) is arranged at each cross member end region (71) of the cross member (7), to which tilting mechanism the respective bracket foot (54) of the tension bracket (5) is fastened, wherein the tension brackets (5) can be angled away from the press table (2) by the tilting mechanism (8), and the press ram (3) has tension bracket supports (9) projecting from a front side (V) and a rear side (R) of the clamping press (1, 1') and corresponding to the inner support (53) of the bracket head (52).

Description

[0001] The present invention relates to a clamping press having a longitudinal direction and a width direction running at right angles thereto, wherein the clamping press comprises a press table, a press ram arranged above the press table, a plurality of press cylinders arranged below the press table, and a plurality of tension yokes, wherein the tension yokes each comprise a closed yoke frame, a yoke head having an inner support, and a yoke foot pivotably attached to a joint of the clamping press.

[0002] The present invention also relates to a clamping press having a longitudinal direction and a width direction running at right angles thereto, wherein the clamping press has a press table, a press ram arranged below the press table, a plurality of press cylinders arranged above the press table, and a plurality of tension brackets, wherein the tension brackets each have a closed bracket frame, a bracket head having an inner support, and a bracket foot which is pivotally attached to a joint of the clamping press.

[0003] In this case, the term “locking press” refers to a device that serves as a locking device in the forming of workpieces, for example, but not exclusively, in internal high-pressure forming.

[0004] In internal high-pressure forming, blanks, typically tubular hollow bodies, are picked up by a forming tool consisting of at least two parts and then fed with a forming medium via the tube ends of the blank. The forming medium, for example, a water-oil emulsion, transfers the pressure required for forming to the inside of the hollow blank, causing it to bulge and conform to the contour of the forming tool, which is closed when the force is applied.

[0005] The molding tool is designed in at least two parts, with one part of the molding tool being mounted on a press table of the clamping press. The other part of the molding tool is mounted on a height-adjustable press ram arranged above the press table. The press ram can be raised and lowered using appropriate lifting cylinders, thereby opening and closing the molding tool.

[0006] The internal pressures required for forming are typically several thousand bar. The clamping forces required to keep the closed mold closed during the forming process are then several meganewtons.

[0007] The required locking forces are applied by appropriately designed locking presses.

[0008] The use of multi-column presses or frame presses as clamping presses is known from the state of the art. However, the use of such presses as clamping presses requires a massive steel structure to withstand the forces to be absorbed. Such systems therefore have considerable heights and enormous dead masses. In addition to complex foundations and the considerable space required, such systems are also very energy-intensive to operate. Such systems are also slow-moving, which increases cycle times between two consecutive forming steps. Tool changes on such systems are also cumbersome.

[0009] From the publication JP H06 328 518 A, a locking device for a two-part casting mold is known, which prevents the mold from opening during a casting process. In this locking device, two pivoting brackets are arranged on a first part of the casting mold. The brackets can be pivoted so that they engage in precisely fitting recesses in a second part of the casting mold.

[0010] A locking device in which a two-part casting mold is held closed by at least two C-shaped clamps is known from the document JP 2002 153 918 A.

[0011] Document CN 2 03 019 605 U discloses a mold locking device for a press. In this device, several struts protrude from the edge of a worktop of the press. The struts are hingedly attached to the worktop and each have an opening. When the press is locked, precisely formed projections, which are formed on a clamping plate arranged opposite the worktop, engage in the openings in the struts. The clamping plate is then fixed in height relative to the worktop by the struts.

[0012] Clamping presses offer significant advantages, as they absorb the force through tension bars that hold the press bed and the press ram together with the forming tool located between them during hydroforming. The tension bars eliminate the need for a complex steel structure for force absorption. A clamping press of this type with tension bars is known from WO 2004 / 004939 A1.

[0013] The clamping press described in WO 2004 / 004939 A1 has a press bed, a press ram arranged above it, and two tension yokes, each of which has a loop-shaped, closed yoke frame and two spaced-apart, half-shell-shaped segments, which are referred to below as the yoke head and yoke foot. The yoke frames are each guided around the yoke head and the associated yoke foot and are firmly connected to them. During the forming of the blank, the tension yokes enclose the press bed and the press ram, with an inner support of the yoke heads resting on the upper side of the press ram. The inner support extends across the entire width of the press ram. The yoke feet are located centrally below the press bed, where several press cylinders of the clamping press are also arranged. The press cylinders press against the yoke feet, which forces them downwards and away from the press bed.Because the tension brackets are guided around the press table and the press ram, the force exerted by the press cylinders on the bracket feet is accompanied by an equal counterforce, which compresses the press ram and the press table and thus also a forming tool arranged between the press ram and the press table.

[0014] The clamp feet are attached to a joint, allowing the clamps to be folded outward, i.e., away from the press ram. When the clamps are folded away, they no longer extend around the press ram, allowing the press ram to be raised to open the mold.

[0015] The clamping press described in WO 2004 / 004939 A1 does not require a complex steel structure to absorb the clamping forces. However, it is only suitable for accommodating smaller forming tools. Large forming tools require large press tables and press rams to accommodate them in the clamping press. In this case, the use of appropriately dimensioned clamping yokes, which must be guided around both the press table and the press ram, proves problematic. In particular, the clamp heads cannot be made arbitrarily large in order to bridge very wide press rams. Clamp heads that are too large would, on the one hand, increase the component mass of the clamp yoke, which is difficult to compensate for structurally and leads to longer cycle times during forming. On the other hand, a greater width of the clamp heads leads to greater differences in the elastic strain between the clamp head and the clamp frame under load.This causes the ironing head to detach from the ironing frame and / or the ironing base, which can cause a tribological problem.

[0016] It is therefore the object of the present invention to provide a clamping press in which even larger forming tools can be accommodated.

[0017] In a first aspect of the invention, the object is achieved by a clamping press with a longitudinal direction and a width direction running at right angles thereto, wherein the clamping press has a press table, a press ram arranged above the press table, several press cylinders arranged below the press table, and several tensioning brackets, wherein the tensioning brackets each have a closed bracket frame, a bracket head having an inner support, and a bracket base pivotably attached to a joint of the clamping press, wherein the press cylinders are arranged below opposite edge regions of the press table, the clamping press has rotatably mounted cross members extending in the width direction of the clamping press below two opposite press cylinders, wherein a tilting mechanism is arranged at each cross member end region of the cross member, to which the respective bracket base of the tensioning bracket is attached,and wherein the tension brackets can each be angled away from the press table by the tilting mechanism and the press ram has projecting tension bracket supports on a front and a rear side of the clamping press and corresponding to the inner support of the bracket head.,

[0018] The object is achieved in a second aspect of the invention by a clamping press with a longitudinal direction and a width direction running at right angles thereto, wherein the clamping press has a press table, a press ram arranged below the press table, several press cylinders arranged above the press table, and several tensioning brackets, wherein the tensioning brackets each have a closed bracket frame, a bracket head having an inner support, and a bracket foot pivotally attached to a joint of the clamping press, wherein the press cylinders are arranged above opposite edge regions of the press table, the clamping press each has rotatably mounted cross members extending in the width direction of the clamping press above two opposite press cylinders, wherein a tilting mechanism is arranged at each cross member end region of the cross member, to which the respective bracket foot of the tensioning bracket is attached,wherein the tensioning brackets can each be angled away from the press table by the tilting mechanism and the press ram has tensioning bracket supports on a front and a rear side of the clamping press which project and correspond to the inner support of the bracket head.

[0019] In this clamping press, a movable press ram is located below a preferably stationary press table. The press table is supported, for example, by a machine frame. To close a tool held in the clamping press, the press ram is moved toward the press table from below.

[0020] The invention will be explained below primarily with reference to the clamping press in which the press ram is arranged above the press bed. The essential features of the invention as well as the fully developed features apply analogously to the clamping press in which the press ram is arranged below the press bed.

[0021] The clamping press according to the invention has a press table to which a first mold part of an at least two-part molding tool can be attached. The clamping press further has a press ram to which a second mold part of the molding tool can be attached. The press ram is arranged so that it can be adjusted in height above the press table. The press table, in turn, is fixed, for example, on several press table legs, and preferably does not change its height during a forming cycle. To open the molding tool accommodated in the clamping press, the press ram is raised. Conversely, the molding tool is closed when the press ram is lowered.

[0022] One long side of the press ram and the press table is aligned in a longitudinal direction of the clamping press. A width direction of the clamping press, running from a front side to a rear side of the clamping press, runs at right angles to this.

[0023] The clamping press comprises a plurality of press cylinders arranged beneath opposite edge regions of the press table. Preferably, a first row of press cylinders is arranged beneath the press table on a first side, and a second row of press cylinders is arranged beneath the press table on a second side opposite in the width direction, with the press cylinders of both rows facing each other in pairs.

[0024] The clamping press comprises a plurality of cross members, each extending beneath two opposing press cylinders in the width direction of the clamping press and each rotatably mounted. The cross members are preferably each formed as a shaft and rotatably mounted such that they can rotate about their rotational axis running in the width direction of the clamping press.

[0025] The clamping press also has several tension yokes. The tension yokes each have a closed yoke frame, a yoke head, and a yoke base. The yoke frame is preferably looped around the yoke head and the yoke base and is preferably firmly connected to the yoke head and the yoke base. The yoke frames are preferably made of carbon fibers, glass fibers, aramid fibers, and / or other reinforcing fibers embedded in a matrix, such as a synthetic resin matrix or a light metal matrix. The yoke heads and the yoke bases are preferably designed as semicircular light metal segments, e.g., made of an aluminum alloy.

[0026] A tilting mechanism is arranged at each cross member end area, to which the stirrup foot of one of the tension stirrups is articulated. The tilting mechanism supports the weight of the connected tension stirrup and allows the tension stirrup to be angled away from the press bed. This movement angles the stirrup head outwards in the width direction so that it does not collide with the protruding tension stirrup supports on the press ram during the pivoting movement in the longitudinal direction. The tilting mechanism is firmly connected to the respective cross member, so that when the cross member rotates, the tilting mechanism pivots around its axis of rotation. The tilting mechanism also allows the stirrup foot attached to it to move towards the cross member, so that when the tension stirrup is tightened, the stirrup foot comes into contact with the cross member.

[0027] The tilting mechanism is formed, for example, by an arrangement of articulated struts that connect the respective stirrup foot to the cross member. A spring acting between the cross member and the attached tilting mechanism allows the stirrup foot to be spaced from the respective cross member end area at the required distance for the tension stirrup to be angled smoothly.

[0028] Because the tilting mechanism, which is firmly connected to the cross member, is pivoted when the cross member rotates, the tension bar, which is connected to the tilting mechanism, is also automatically pivoted when the cross member rotates, allowing it to be moved back and forth between a vertical position and a horizontal position.

[0029] The press ram has projecting clamping bracket supports on the front and rear of the clamping press, each designed to correspond to the inner supports of the clamping heads, onto which the inner supports of the clamping heads can be placed. Preferably, the press ram and the clamping bracket supports projecting from these supports on the front and rear are formed from a single piece.

[0030] When forming a blank, the tension stirrups are first positioned vertically in the pivoting direction and then folded onto the press table so that the inner supports of the stirrup heads are each positioned over the corresponding tension stirrup receptacles of the press ram. When the press cylinders are retracted, there is a gap between the inner supports of the stirrup heads and the corresponding tension stirrup receptacles of the press ram, allowing the inner supports to be folded over the respective tension stirrup supports without hitting the press ram. Likewise, when the press cylinders are retracted, the stirrup feet are spaced from the respective cross member end area by a gap so that they too do not hit the cross member when the tension stirrups are folded in and out.

[0031] When the press cylinders extend, the cross members arranged below them are moved downwards. This closes the gaps between the inner supports of the clamp heads and the tension clamp supports, as well as the gaps between the clamp feet and the cross members. When the clamping press is closed, the press cylinders press the cross members arranged below them against the respective clamp feet, which puts tension on the tension clamps. The tension clamps transmit force between the respective cross member and the respective tension clamp supports of the press ram, holding the press ram and the press table, and thus the forming tool located between them, together during the forming of a molded part.

[0032] The locking press according to the invention is distinguished from previously known locking presses by a number of advantages: The clamping yokes are arranged in pairs opposite each other at the front and rear of the clamping press and can thus be guided over the clamping yoke supports projecting at the front and rear of the press ram. This eliminates the need to route the clamping yokes around the entire press ram and press table. The clamping yoke heads therefore only need to be dimensioned so that their inner support extends over one of the clamping yoke supports projecting at the front and rear. The clamping yoke heads can therefore be dimensioned independently of the width of the press ram.

[0033] In the longitudinal direction of the locking device according to the invention, several tension brackets can be arranged next to one another in order to ensure adequate force transmission between the press table and the press ram even in the case of very long press tables and press rams.

[0034] Due to the clever arrangement of the tension brackets, the press table and the press ram of the locking press according to the invention can be designed in a very large format, whereby the bracket heads can be designed smaller than in previously known locking presses in which the tension brackets are guided around the press ram over the entire width of the latter.

[0035] Because the press cylinders are arranged under opposite edge areas of the press table, they each press against the crossbeam below at the crossbeam end areas. Force transmission between one of the press cylinders and the crossbeam below thus occurs close to the point of force transmission between the crossbeam and the stirrup foot resting against it. The crossbeam is therefore only subjected to two oppositely directed force pairs at its crossbeam end areas. This ensures a lower and constant bending load on the crossbeam, which can therefore be made as long as desired without having to simultaneously increase the cross-section of the crossbeam. The crossbeams therefore do not represent a restriction when dimensioning the width of the press table.

[0036] A further advantage of the clamping press according to the invention is that the clamping brackets can be easily folded in the longitudinal direction of the clamping press during the feeding and removal of the molded parts and when changing the molding tool. To do this, the clamping brackets are first angled using the respective tilting mechanism and then pivoted into a preferably horizontal position by rotating the cross members. This allows unobstructed access to the molding tool from the front and / or rear of the clamping press.

[0037] If the press ram is arranged below the press table, there is even completely unhindered access to the press ram, as the tension brackets can then be swung upwards, i.e. away from a working area required for a tool or blank change.

[0038] The pivoting movement of the drawbars can be synchronized using a suitable mechanism. For this purpose, a non-rotatable pivot lever is attached to each cross member. The pivot levers are connected to each other by coupling rods and actuated by a linear drive, preferably a hydraulic cylinder, via a push rod. This allows for easy control of the movement of even a large number of drawbars.

[0039] The angles by which the tension yokes are folded down must be designed so that when folded in the longitudinal direction of the clamping press, the tension yokes can be placed close together like a fan. This means that the tension yokes neither interfere with each other when folded down, nor do they have to be placed on top of each other when pivoting into a horizontal position. When rotatably mounting the cross members, it is particularly advantageous if the cross members are mounted in ball joint bearings connected to the press cylinders. The ball joint bearings enable the cross members to rotate, similar to a pivot bearing. In addition, mounting the cross member in ball joint bearings offers the additional advantage that the ball joint bearings and the press cylinders can follow any bending of the cross member and thus are not damaged, even if the cross members mounted therein bend under the influence of strong clamping forces.

[0040] The clamping movements on the clamping press according to the invention can be synchronized by guiding the cross members through at least two pivot bearings connected to each other via a clamping press support plate. The support plate is aligned parallel to the press table and arranged either above or below the cross members. The support plate is preferably made of a steel sheet at least 20 to 40 mm thick.

[0041] It proves particularly advantageous if at least one guide cylinder-piston arrangement is formed between the support plate and the press table. In this case, for example, a vertically downward-projecting guide cylinder is arranged in the center of the press table and rigidly connected to an underside of the press table. A piston matching the guide cylinder is then formed on an upper side of the support plate and is inserted into the guide cylinder from below. The guide cylinder-piston arrangement ensures that the press table and the support plate always remain exactly parallel to one another when the press cylinders are extended and retracted, and that the tension yoke feet move synchronously against the contact surfaces of the cross member end areas and the tension yoke supports of the press rams. This device can also absorb any off-center forces that may occur during the press ram movement.

[0042] The arrangement of the guide cylinder and piston on the press table and the support plate can, of course, also be reversed. Likewise, instead of a single guide cylinder-piston arrangement located centrally on the press table, several conveniently arranged guide cylinder-piston arrangements can be formed between the support plate and the press table.

[0043] Preferably, the tensioning brackets arranged at the front and rear are each connected by a coupling mechanism comprising coupling rods, each connected to the cross members and to at least one linear drive via a pivoting lever. This ensures that the tensioning brackets perform a smooth movement when pivoting.

[0044] To enable an advantageous folding movement of the respective tension yoke, it is particularly advantageous if the tilting mechanism has a ball-and-socket bearing arranged on a cross member end face, wherein the yoke foot attached to the tilting mechanism is fastened to the ball-and-socket bearing. The ball-and-socket bearings are preferably prevented from rotating by a corresponding locking mechanism, so that the tension yoke attached to the ball-and-socket bearing can only perform a tilting movement, but not a pivoting movement, relative to the ball-and-socket bearing. Thus, in this case, too, a pivoting movement of the tension yoke occurs exclusively through a rotation of the cross member, on whose cross member end face the respective ball-and-socket bearing is arranged.Bearing rotation within the ball joint bearing can be prevented, for example, by a key that is inserted into corresponding grooves in the parts of the ball joint bearing that can rotate relative to one another.

[0045] To achieve high guidance accuracy of the press ram, it is recommended that the clamping press have guide columns, each of which extends between the press bed and a cross member running parallel to the press bed. In this embodiment of the invention, the clamping press has a cross member arranged above or below the press ram, which, for example, is attached to a machine frame formed around the press bed or is a component thereof. For example, the clamping press can be equipped with guide columns, each of which preferably extends between the press bed and a cross member arranged above the press ram.

[0046] The guide columns, for example, are rigidly connected to the press table and the crosshead. The guide columns are preferably guided through the press ram at the corners of the ram.

[0047] The stiffening of the clamping press according to the invention by the guide columns can be further improved if the guide columns run through guide sleeves held in or on the press ram.

[0048] If only self-guiding tools are to be used on the clamping press, the clamping press can also be equipped with soft guides, such as suspended guides, to limit the forces resulting from over-determination. In this design, the suspended guides are suspended from a support frame of the clamping press at a relatively short distance.

[0049] In a preferred embodiment of the invention, the clamping press has two ram lifting cylinders arranged on either side of the press table in the longitudinal direction of the clamping press and connected to the press ram. The press ram can be raised and lowered by the ram lifting cylinders, opening and closing a forming tool arranged between the press table and the press ram. The ram lifting cylinders are each arranged opposite press table ends spaced apart in the longitudinal direction of the clamping press. By arranging the ram lifting cylinders opposite the press table ends, unhindered access to the press table via both the front and rear of the clamping press is not blocked by the ram lifting cylinders.

[0050] In another embodiment, it is also possible to realize the lifting movement of the press ram by means of a ram lifting cylinder arranged centrally between a cross member running parallel to the press table and the press ram.

[0051] Advantageous embodiments of the locking press according to the invention, their structure, function and advantages are explained below with reference to figures, wherein Fig. 1 schematically shows an embodiment of the clamping press according to the invention in a side view; Fig. 2 schematically shows an embodiment of a tilting mechanism of the clamping press from Fig. 1 shows; Fig. 3 schematically shows a part of the clamping press Fig. 1 with vertically positioned tensioning brackets in a front view; Fig. 4 schematically shows a part of the clamping press Fig. 1 with horizontally folded tension brackets in a front view; Fig. 5 schematically shows a part of the clamping press Fig. 1 with vertically positioned tensioning brackets in a top view; Fig. 6 schematically shows a part of the clamping press Fig. 1 with horizontally folded tension brackets in a top view; and Fig. 7 schematically shows a part of another embodiment of the locking press according to the invention in a front view.

[0052] In Fig. 1 schematically shows an embodiment of the locking press 1 according to the invention in a side view.

[0053] The clamping press 1 comprises a press table 2 and a press ram 3 arranged above the press table 2. A molded part (not shown here) of an at least two-part molding tool can be attached to the press table 2 and the press ram 3. The press ram 3 is arranged so that it can be moved in height above the press table 2. The press table 2, however, stands fixedly on several press table legs 21, which, for the sake of clarity, are shown in the Fig. 1 shown side view of the locking press 1, but in the Fig. 3 and Fig. 4. To open a forming tool held in the clamping press 1, the press ram 3 is raised. Conversely, the forming tool is closed when the press ram 3 is lowered. In the embodiment shown, the press table 2 does not change its height during a forming cycle.

[0054] The locking press 1 shown has a longitudinal direction L and a width direction B running at right angles thereto, which runs from a front side V to a rear side R of the locking press 1. A long side of the press ram 3 and the press table 2 is aligned in the longitudinal direction L of the locking press 1.

[0055] The clamping press 1 has a plurality of pressing cylinders 4 arranged beneath opposite edge regions of the press table 2. In the illustrated embodiment of the clamping press 1 according to the invention, a first row of pressing cylinders 4 is arranged beneath the press table 2 on a first side, and a second row of pressing cylinders 4 is arranged beneath the press table 2 on a second side opposite in the width direction B, so that the pressing cylinders 4 of both rows are arranged opposite one another in pairs.

[0056] The clamping press 1 has a plurality of cross members 7, each of which extends under two opposing press cylinders 4 in the width direction B of the clamping press 1 and is each rotatably mounted. In the embodiment shown, the cross members 7 are each designed as a rotatably mounted shaft. The cross members 7 can rotate about their rotational axis extending in the width direction B of the clamping press 1.

[0057] The locking press 1 has a plurality of tension yokes 5. In the embodiment of the locking press 1 shown, three tension yokes 5 are arranged on the front side V and the rear side R of the locking press 1. In other embodiments of the invention, fewer or more than three tension yokes 5 can be arranged on the front side V and the rear side R of the locking press 1. The tension yokes 5 each have a closed yoke frame 51, a yoke head 52, and a yoke base 54. The yoke frame 51 is looped around the yoke head 52 and the yoke base 54 and is firmly connected to the yoke head 52 and the yoke base 54. The yoke frames 51 of the embodiment shown are made of carbon fibers embedded in a matrix, which is usually a plastic matrix. Instead of carbon fibers, glass fibers, aramid fibers, and / or comparable reinforcing fibers are also very suitable for forming the yoke frames 51.The bracket heads 51 and the bracket feet 54 are designed as semicircular light metal segments made of an aluminum alloy.

[0058] The cross members 7 have cross member end regions 71, on each of which a tilting mechanism 8 is arranged. The bracket feet 54 of the tension brackets 5 are each pivotally connected to the tilting mechanism 8. The tilting mechanism 8 supports the weight of the connected tension bracket 5 and enables the tension bracket 5 to be angled away from the press table 2. In the embodiment of the invention shown here, the tension brackets 5 can be angled by at least 5° from the press table 2. In an embodiment of the locking press 1 according to the invention, not shown here, the tension brackets 5 can be angled by at least 10° from the press table 2. When angled, the tension brackets 5 remain connected to the tilting mechanism 8 at the bottom and fold away from the press ram 3 at the top.

[0059] In the embodiment shown, the tilting mechanism 8 is rotationally fixedly connected to the respective cross member 7, so that the tilting mechanism 8 is pivoted about its axis of rotation when the cross member 7 rotates. The tilting mechanism 8 also allows the bracket foot 54 attached thereto to move toward the cross member 7, so that the bracket foot 54 comes into contact with the cross member end region 71 when the tension bracket 5 is tightened. Likewise, the tilting mechanism 8 allows the bracket foot 54 attached thereto to move away from the cross member end region 71, so that the bracket foot 54 does not hit the cross member 7 when the tension bracket 5 is bent away from the press table 2.

[0060] A possible embodiment of the tilting mechanism 8 is shown in Fig. 2. In this embodiment, the tilting mechanism 8 is formed by an arrangement of articulated struts 81, 82, through which the respective bracket foot 54 is connected to the cross member 7. The tilting mechanism 8 also has a spring 83. The spring 83 acts between the cross member 7 and the strut 82 of the tilting mechanism 8, which runs in the width direction B of the clamping press 1. The spring 83 presses the strut 82 away from the cross member 7, so that the bracket foot 84 is spaced from the cross member end region 71 when the tension brackets 5 are not tensioned. A spacing thus created by the spring 83 in the unstressed state of the tensioning bracket 5 between the bracket foot 84 and the cross member end region 71 ensures a stop-free bending of the tensioning bracket 5. When the tensioning bracket 5 is tensioned, the spring 83 is compressed until the bracket foot 54 rests on the cross member end region 71.The tilting movement of the tension yoke 5 is then effected by a working piston 84 of the tilting mechanism 8.

[0061] Because the tilting mechanism 8, which is firmly connected to the cross member 7, is pivoted when the cross member 7 rotates, the tension bracket 5, which is connected to the tilting mechanism 8, is also automatically pivoted when the cross member 7 rotates, whereby it can be moved back and forth between a vertical position and a horizontal position.

[0062] The press ram 3 has, as shown in Fig. 1, the clamping press 1 has tension yoke supports 9 that project toward the front V and rear R of the clamping press 1 and are each configured to correspond to the inner supports 53 of the yoke heads 52, on which the inner supports 53 of the yoke heads 52 can be placed. In the embodiment of the invention shown, the press ram 3 and the tension yoke supports 9 projecting from the front and rear thereof are formed from a single piece. However, the tension yoke supports 9 can also be formed separately and, for example, inserted into correspondingly configured receiving openings on the side of the press ram 3.

[0063] As it is in Fig. 1, the embodiment of the invention shown here has ball joint bearings 10 in which the cross members 7 are each rotatably mounted on both sides. The ball joint bearings 10 are connected to the press cylinders 4. In other embodiments of the invention, the cross members 7 are mounted in pivot bearings. The ball joint bearings 10 enable, similar to a pivot bearing, a rotation of the cross members 7 about the rotation axis of the cross members 7 running in the width direction B. In addition, the reception of the cross member 7 in the ball joint bearings 10 offers the advantage that the ball joint bearings 10 can follow a bending of the cross member 7. Thus, the ball joint bearings 10 are not damaged, even if the cross members 7 received therein bend under the influence of strong clamping forces.

[0064] In the embodiment of the locking press 1 shown, the cross members 7 are each additionally guided through two pivot bearings 12 connected to one another via a support plate 11 of the locking press 1. The support plate 11 is aligned parallel to the press table 2 and, in the embodiment shown, is arranged above the cross members 7. The cross members 7, which are arranged parallel to one another and each pass through the pivot bearings 12, are also connected to the support plate 11 via the pivot bearings 12 connected to the support plate 11. This synchronizes the press cylinders 4 of the locking press 1 and ensures that they extend smoothly. The support plate 11 can also be arranged below the cross members 7. In the embodiment shown, the support plate 11 is made of a 30 mm thick steel sheet.Depending on the dimensions of the locking press 1, a thinner steel sheet, for example a 20 mm thick steel sheet, or a thicker steel sheet, for example a 40 mm thick steel sheet, can be used.

[0065] In the embodiment of the clamping press 1 shown here, a guide cylinder-piston arrangement 18 is formed between the support plate 11 and the press table 2. This is shown in the Fig. 3 and Fig. 4 shown in dashed lines, as they are in the Fig. 3 and Fig. 4, the embodiment of the clamping press 1 shown there is hidden behind the central press cylinder 4. The guide cylinder-piston arrangement 18 has a guide cylinder that projects vertically downwards and is rigidly connected to an underside of the press table 2, which is arranged centrally of the press table 2. On an upper side of the support plate 11, a piston matching the guide cylinder is formed, which is inserted into the guide cylinder from below. The guide cylinder-piston arrangement 18 ensures that the press table 2 and the support plate 11 always remain precisely parallel to one another when the press cylinders 4 are extended and retracted.

[0066] The arrangement of the guide cylinder and the piston on the press table 2 and the support plate 11 can of course also be reversed. Likewise, instead of a guide cylinder-piston arrangement 18 arranged centrally on the press table 2, several expediently arranged guide cylinder-piston arrangements 18 can also be formed between the support plate 11 and the press table 2.

[0067] The embodiment of the clamping press 1 according to the invention shown here has guide columns 13, each of which extends between the press table 2 and a cross member 14 arranged above the press ram 3 and each of which passes through the press ram 3. The cross member 14 is supported by a machine frame 17 formed around the press table 2.

[0068] In the illustrated embodiment of the clamping press 1, the guide columns 13 extend through precisely fitting guide sleeves 15, which are held in corner areas of the press ram 3. The guide sleeves 15 can also be arranged laterally of the press ram 3.

[0069] As it is in Fig. 1, the clamping press 1 in the embodiment shown here has two ram lifting cylinders 16, which are arranged in the longitudinal direction L of the clamping press 1 on both sides of the press table 2 and are connected to the press ram 3. The press ram 3 can be raised and lowered by the ram lifting cylinders 16, whereby a forming tool arranged between the press table 2 and the press ram 3 is opened and closed. The ram lifting cylinders 16 are each arranged opposite press table ends spaced apart in the longitudinal direction L of the clamping press 1, whereby unhindered access to the press table 2 is possible via both the front V and the rear R of the clamping press 1.

[0070] The functioning of the embodiment of the locking press 1 shown here is explained below.

[0071] For a tool change of a forming tool to be accommodated in the clamping press 1, the tension brackets 5, as shown in the Fig. 4 and Fig. 6, unwound from the press table 2 and pivoted into a horizontal position. Since the tension brackets 5 can be angled sufficiently far within an angular range permitted by the tilting mechanism 8, the tension brackets 5 can be placed close to one another, as in a fan, and do not necessarily have to be placed on top of one another or overlapping one another.

[0072] When changing the molding tool, as well as when inserting a blank into the molding tool, the press ram 3 is spaced appropriately far from the press table 4 by the ram lifting cylinders 16. To close the molding tool, the ram lifting cylinders 16 retract, causing the press ram 3 to lower.

[0073] Before forming a blank, the tension stirrups 5 are, as shown in the Fig. 3 and Fig. 5, is initially positioned vertically and angled to the press table 2 so that the inner supports 53 of the clamp heads 52 are each arranged above the corresponding clamping bracket receptacles 9 of the press ram 3. With the press cylinders 4 still retracted, the inner support 53 of the clamping bracket 5 can be guided over the corresponding clamping bracket receptacle 9 of the press ram 3 without striking.

[0074] Likewise, when the press cylinders 4 are still retracted, the stirrup feet 54 are each spaced apart from the respective cross member end area 71 by a gap so that they do not strike when the tension stirrups 5 are bent up or down.

[0075] When the press cylinders 4 extend, the cross members 7 arranged underneath them are moved downward. This closes the gaps between the inner supports 53 of the clamp heads 52 and the tension clamp supports 9, as well as the gaps between the clamp feet 54 and the cross member end areas 71. When the clamping press 1 is closed, the press cylinders 4 press the cross members 7 arranged underneath them against the respective clamp feet 54, thereby placing the tension clamps 5 under tension. The tension clamps 5 transmit force between the respective cross member 7 and the respective tension clamp supports 9 of the press ram 3.

[0076] In the embodiment of the locking press 1 shown here, the tilting mechanisms 8 each have their own electric motor-driven working piston 84, with the working pistons 84 each being individually pneumatically controlled. A synchronized pivoting and tilting movement of the clamping yokes 5 is thus achieved by a correspondingly controlled control of the individual working pistons. Likewise, only individual clamping yokes 5 can be tilted.

[0077] In a Fig. In the embodiment of the locking press 1' according to the invention shown in Figure 7, the tension yokes 5 arranged on the front side V and the rear side R are each connected by a coupling mechanism. The coupling mechanism has a plurality of coupling rods 19, by means of which the tension yokes 5 arranged on the front side V and the rear side R are each pivoted synchronously in the longitudinal direction L of the locking press 1'. As a result, the tension yokes 5 perform a coordinated, orderly movement and do not have to be pivoted individually. To move the coupling rods, they are connected to a linear drive 22, for example a hydraulic cylinder, via at least one pivot lever 20.By means of the coupling rods 19, a drive movement of the linear drive 22, which is transmitted to them by the pivoting lever 20, is converted into a synchronized pivoting movement of the tensioning brackets 5, in which the tensioning brackets 5 are pivoted in a fluid movement sequence in the longitudinal direction L of the locking press 1'.

[0078] How it looks Fig. 3, several tension brackets 5 can be arranged in the longitudinal direction L of the locking press 1 in order to ensure adequate force transmission between the press table 2 and the press ram 3 even in the case of very long press tables 2 and press rams 3.

[0079] As the Fig.3 to 6, the tension yokes 5 are arranged in pairs opposite one another on the front V and the rear R of the locking press 1 and can thus be guided over the tension yoke supports 9 projecting at the front and rear of the press ram 3. This means that the tension yokes 5 do not have to be guided around the entire press ram 3 and the press table 2. The yoke heads 52 therefore only need to be dimensioned such that their inner support 53 extends just over one of the tension yoke supports 9 projecting at the front and rear. The yoke heads 52 can therefore be dimensioned independently of the width of the press ram 3.

[0080] Overall, with the clamping press 1, 1' according to the invention, even large-format press tables 2 together with press rams 3 can be realized very easily, while always maintaining very good accessibility to the molding tool accommodated therein.

Claims

[1] A clamping press (1, 1') having a longitudinal direction (L) and a width direction (B) running at right angles thereto, wherein the clamping press (1, 1') comprises a press table (2), a press ram (3) arranged above the press table (2), a plurality of press cylinders (4) arranged below the press table (2), and a plurality of tension yokes (5), wherein the tension yokes (5) each comprise a closed yoke frame (51), a yoke head (52) having an inner support (53), and a yoke foot (54) pivotably attached to a joint (6) of the clamping press (1, 1'), characterized byin that the pressing cylinders (4) are arranged under opposite edge regions of the press table (2), the locking press (1, 1') has rotatably mounted cross members (7) which extend in the width direction (B) of the locking press (1, 1') under two opposite pressing cylinders (4), wherein a tilting mechanism (8) is arranged on each of the cross member end regions (71) of the cross member (7), to which tilting mechanism the respective bracket foot (54) of the tension bracket (5) is fastened, wherein the tension brackets (5) can each be angled away from the press table (2) by the tilting mechanism (8), and the press ram (3) has tension bracket supports (9) on a front side (V) and a rear side (R) of the locking press (1, 1') which project and correspond to the inner support (53) of the bracket head (52). [2] A clamping press (1, 1') having a longitudinal direction (L) and a width direction (B) extending at right angles thereto, wherein the clamping press (1, 1') comprises a press table (2), a press ram (3) arranged below the press table (2), a plurality of press cylinders (4) arranged above the press table (2), and a plurality of tension yokes (5), wherein the tension yokes (5) each comprise a closed yoke frame (51), a yoke head (52) having an inner support (53), and a yoke foot (54) pivotably attached to a joint (6) of the clamping press (1, 1'), characterized byin that the pressing cylinders (4) are arranged above opposite edge regions of the press table (2), the locking press (1, 1') has rotatably mounted cross members (7) which extend in the width direction (B) of the locking press (1, 1') above two opposite pressing cylinders (4), wherein a tilting mechanism (8) is arranged on each of the cross member end regions (71) of the cross member (7), to which tilting mechanism the respective bracket foot (54) of the tension bracket (5) is fastened, wherein the tension brackets (5) can each be angled away from the press table (2) by the tilting mechanism (8), and the press ram (3) has tension bracket supports (9) on a front side (V) and a rear side (R) of the locking press (1, 1') which project and correspond to the inner support (53) of the bracket head (52). [3] Locking press according to claim 1 or 2, characterized by that the cross members (7) are accommodated in ball joint bearings (10) connected to the press cylinders (4). [4] Locking press according to one of the preceding claims, characterized by that the cross members (7) are each guided through at least two pivot bearings (12) connected to one another via a support plate (11) of the locking press (1, 1'). [5] Locking press according to claim 4, characterized by that at least one guide cylinder-piston arrangement (18) is formed between the carrier plate (11) and the press table (2). [6] Clamping press according to one of the preceding claims, characterized by that the tension brackets (5) arranged on the front (V) and the rear (R) are each connected by a coupling mechanism which has coupling rods (19) which are each connected via a pivoting lever (20) to the cross members (7) and to at least one linear drive (22). [7] Clamping press according to one of the preceding claims, characterized bythat the tilting mechanism (8) has a ball joint bearing arranged on a cross member end face (72), wherein the bracket foot (54) fastened to the tilting mechanism (8) is fastened to the ball joint bearing. [8] Clamping press according to one of the preceding claims, characterized by that the locking press (1, 1') has guide columns (13) which each extend between the press table (2) and a cross member (14) running parallel to the press table (2). [9] Locking press according to claim 8, characterized by that the guide columns (13) run through guide sleeves (15) held in or on the press ram (3). [10] Clamping press according to one of claims 1 to 7, characterized by that hanging guides for the press ram (3) hang on a support frame of the locking press (1, 1'). [11] Clamping press according to one of the preceding claims, characterized bythat the locking press (1, 1') has at least two ram lifting cylinders (16), which are each arranged opposite the press table (2) in the longitudinal direction (L) of the locking press (1, 1') and are connected to the press ram (3), or one ram lifting cylinder (16) which is arranged centrally between a cross member (14) running parallel to the press table (2) and the press ram (3).

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