The invention relates to a clamping system for a press brake, the clamping system comprising an elongate beam comprising a receiving space for receiving a part of a bending tool, a clamping element, the clamping element being movable between a first position, in which it may engage on the bending tool for clamping it in the receiving space, and a second position for releasing the bending tool, and an actuating member for displacing the clamping element, the actuating member being movable between an active position, in which it urges the clamping element towards the first position, and an inactive position in which it allows the clamping element to move to the second position.
Press brakes are machines used for bending or folding sheet material, such as metal sheets. For that purpose, press brakes include a bottom beam and a top beam, which are movable with respect to each other. The top and bottom beams both hold tools, between which a workpiece is provided for bending. In general, bending tools of a press brake are exchangeable to allow making different types of bends or folds, and to allow servicing the tools. Therefore, press brakes are provided with a clamping system which can releasably clamp the tools Clamping systems may be provided on the top beam of the press brake, on the bottom beam, or on both.
Two types of press brakes can be distinguished. The first type has a clamping system that is an integral part of either the top or bottom beam. A further clamping system may or may not be provided for the other of the top or bottom beam. Such a clamping system, that is an integrated one, can not be detached from its top or bottom beam, and is itself thus not exchangeable with another clamping system, whereas the tools the clamping system can hold are exchangeable. The second type has an exchangeable clamping system that can be fixedly connected to either the top beam or the bottom beam. A further clamping system may or may not be provided for the other of the top or bottom beam. The exchangeable clamping system allows exchanging tools, but can also be detached from its top or bottom beam, for instance for maintenance or for exchanging it for another clamping system. This is in the art used to make one press brake suitable for different tooling types, which may require different clamping systems, and/or to service the clamping system.
Further clamping systems exist that can be clamped by other clamping systems as if they were a tool. Such clamping systems can for instance be clamped by a system for tools of a first type, whereas they themselves can clamp tools of a second type, so that such clamping systems act as an adaptor between a clamping system and a tool that would otherwise be incompatible.
The invention relates to clamping systems integrated with press brakes, be it in the bottom beam or top beam, exchangeable clamping systems, and clamping systems acting as an adaptor.
A press brake and a clamping system therefor are known, for instance from applicant's earlier application WO 2010/056110 A1, which describes a clamping device for clamping a tool. The clamping device includes an actuated member and an engaging member. The actuated member is driven for instance hydraulically or pneumatically.
Although the clamping device described in WO 2010/056110 A1 has performed satisfactory, and to this day still does, a need exists to further improve the clamping device. This need exists in particular in relation to the time needed to change tools, since by decreasing the time needed to change tools, the press brake could be used more efficiently.
Therefore, the invention aims to provide a clamping system that can be operated more efficiently.
According to the invention, this aim is achieved by a clamping system for a press brake according to the preamble, characterized by a first biasing member acting on the actuating member for biasing the actuating member towards its inactive position.
The applicant has found that a relatively large part of the time needed for changing tools is taken up by displacing the clamping element towards its second position, in order to release the tool. To move the clamping element towards its second position, for instance in the case of the actuating member being pneumatically or hydraulically driven, pneumatic or hydraulic pressure on the actuating member needs to be stopped, and pneumatic or hydraulic fluid may need to flow back, to allow the actuating member to return to its inactive position. It may however take up to over ten seconds for the pneumatic or hydraulic fluid to have receded sufficiently for releasing the tool. To facilitate the pneumatic or hydraulic fluid receding, a first biasing member is provided that acts on the actuating member. The biasing member biases the actuating member to its inactive position, thereby forcing out pneumatic or hydraulic fluid upon sufficient release of pneumatic or hydraulic pressure. As a result, the time needed to move the actuating member back to its inactive position, and thus for allowing release of the tool, can be shortened, for instance to a period of approximately one to two seconds.
The first biasing member may of course also be used to perform a similar function when drive means other than pneumatic or hydraulic drive means are used.
It is noted that the first biasing member acting on the actuating member, instead of for instance on the clamping element, may provide a relatively large space for the first biasing member. In particular, a first biasing member acting on the actuating member may be relatively long and/or relatively wide. Accordingly, the first biasing member may therefore be relatively large, which in the case of e.g. a compression spring allows for a relatively high spring constant, so that the compression spring may provide a relatively large biasing force, which aids in reducing the time needed to move the actuating member. The length of the spring may also or alternatively allow a relatively large range of motion of the actuating member while being biased by the spring.
The relatively large range of motion of the actuating member may be of particular importance in cases where a relatively large stroke of the clamping element is needed. Clamping systems exist that include a protrusion acting as a hanger or hook on the inside of the receiving space, upon which a tool can be supported and/or hung. Since the tool needs sufficient space inside the receiving space to maneuver it around the protrusion for inserting or removing the tool, the receiving space is relatively broad as compared to the tool. Such clamping systems require a relatively large stroke of the clamping element, since the clamping element must traverse at least partly the relatively broad receiving space.
It is noted that a force provided by the first biasing member may need to be overcome to move the actuating member to its active position. Thus, the total force needed to clamp a tool is increased by the first biasing member. This can be achieved by selecting suitably strong drive means, such as hydraulic or pneumatic drive means, to drive the actuating member.
The first biasing member acting on the actuating member may herein be understood as that the first biasing member acts first on the actuating member. Of course, the actuating member may in that case act for instance on the clamping element or for instance drive means. It must be understood that biasing means acting first on for instance the clamping element, whilst the clamping element acts on the actuating member, are not herein understood to act on the actuating member. Accordingly, the first biasing member may act on the actuating member directly.
The first biasing means may act on any element that moves in the same direction and with the same speed as the actuating member, e.g. any element that is fixedly connected to the actuating member.
In an embodiment of the clamping system, the clamping system having a pressing direction, the first biasing member is arranged substantially parallel to the pressing direction. The first biasing member may as such be arranged vertically.
Having the biasing member substantially parallel to the pressing direction allows for a relatively compact construction of the press brake. In particular, the first biasing member could be arranged at least partly along the receiving space. Additionally or alternatively, this embodiment allows using a relatively long first biasing member in a relatively small, in particular relatively narrow, elongate beam.
Providing a compact construction may aid in reducing a risk of a workpiece colliding with the press brake. As an example, when a workpiece is to be bent multiple times, for instance in different locations, it may fold back towards the elongate beam. The elongate beam could in that case limit the size of the workpiece and/or the amount of bends that can be made in the workpiece, before the elongate beam blocks the workpiece while bending. As such, compactly constructing the press brake is important to allow as much room for the workpiece as possible, so that complex geometries, with many fold, and/or relatively large workpieces may be bent using the press brake.
These advantages could be achieved in a press brake according to the preamble of claim 1, characterized in that the press brake defines a pressing direction, wherein the first biasing member is arranged substantially parallel to the pressing direction. Thus, when the first biasing member is arranged substantially parallel to the pressing direction, the first biasing member need not in all cases act on the actuating member.
The pressing direction is understood as the direction in which a tool clamped by the clamping system is moved with respect to another tool in order to bend a workpiece. The pressing direction may correspond to a depth direction of the receiving space. The pressing direction may be vertical.
In another embodiment of the clamping system, the actuating member is movable in a direction substantially parallel to the pressing direction between its active and inactive position.
When the actuating member is movable substantially parallel to the pressing direction, drive means for driving the actuating member may be placed towards for instance the top or bottom of the actuating member instead of towards a side thereof. As such, such clamping system may be constructed relatively compactly. It is noted that when the elongate beam is a top beam, the drive means may be placed towards the top of the actuating member, whereas when the elongate beam is a bottom beam, the drive means may be placed towards the bottom of the actuating member.
In yet another embodiment of the clamping system the first biasing member extends at least partly in a first cavity in the actuating member, or extends at least partly around the actuating member.
Accordingly, the first biasing member is disposed either partly in or partly around the actuating member. As such, the first biasing member may be relatively long without requiring a relatively large accommodating space extending beyond the first biasing member. A relatively long first biasing member may in particular be useful for providing a biasing force over a relatively long movement path.
It is noted that the first biasing member extending at least partly around the actuating member should be interpreted as that the first biasing member surrounds the actuating member for at least a portion of the length of the first biasing member. Thus, the first biasing member encompasses a part of the actuating member at least partly. The first biasing member being merely arranged in the vicinity of the actuating member, is not understood to constitute the first biasing member extending around the actuating member.
Throughout this application, words denoting numerals, such as first, second, third etc. are used solely to distinguish between one and the other of something. Accordingly, the cavity in the actuating member being referred to as first cavity does not imply there are more cavities in the actuating member. Moreover, a second cavity does not necessarily have to be a cavity in the actuating member.
In yet another embodiment of the clamping system, the first biasing member is arranged on a side of the actuating member proximate the clamping element.
Placing the first biasing member proximate the clamping element allows the first biasing member to push the biasing member back to its inactive position. Moreover, this leaves free the distal end of the actuating member for drive means to engage on the actuating member.
In yet another embodiment of the clamping system, the clamping system comprises a first stop for limiting movement of the actuating member beyond its active position.
By limiting the movement of the actuating member, damage to the first biasing member, for instance by overly compressing them, may be prevented. Accordingly, the first stop may be separate from an engaging surface upon which the first biasing member is supported.
In yet another embodiment of the clamping system, the clamping element is movable in a direction substantially perpendicular to the pressing direction and to a longitudinal direction of the elongate beam between its first and second position. The clamping element may be movable horizontally.
This allows retracting the clamping element away from the receiving space to release the tool, towards a side of the elongate beam.
In yet another embodiment of the clamping system, the clamping system comprises a second biasing member acting on the clamping element, for biasing the clamping element towards the second position.
Biasing the clamping element to the second position ensures that the clamping element moves to the second position when the actuating member is moved to its inactive position, which aids in releasing a tool. Moreover, the second biasing member may aid the first biasing member in pushing back the actuating member, by providing a force directing the biasing member towards in its inactive position via the clamping element. Thus, the second biasing member aids in achieving the advantages described in relation to the first biasing member.
When the first and second biasing means are used together, a relatively large total biasing force may be generated, especially in a limited amount of space. Accordingly, the clamping system of this embodiment may be constructed relatively compactly.
It is noted that the first and/or second biasing member may comprise an elastically deformable element, that deforms upon movement of the actuating member or clamping element respectively, and provides an elastic force in the opposing direction for biasing the actuating member or clamping element respectively. Other suitable biasing means may be used alternatively, such as gas springs.
In yet another embodiment of the clamping system the second biasing member is arranged substantially perpendicular to the pressing direction and to a longitudinal direction of the elongate beam. The second biasing member may be arranged horizontally.
Arranging the second biasing member in this direction may aid in enabling a compact construction.
In yet another embodiment of the clamping system, the second biasing member extends at least partly in a second cavity in the elongate beam.
In this embodiment, the second biasing member may be relatively long, whilst allowing the elongate beam to be constructed relatively compactly. Accordingly, the second biasing member may have a relatively large range of motion. Moreover, if the second biasing member comprises a compression spring, arranging the spring at least partly in the second cavity allows selecting a suitable spring with a suitable spring constant.
Note that the cavity in the elongate beam is referred to as second cavity only to distinguish it from the cavity in the first biasing means, which is referred to as first cavity. There need not be additional cavities in the elongate beam, and the first and second cavity need not have anything in common apart from both being cavities.
In yet another embodiment of the clamping system, the clamping element comprises a protrusion for engaging the second biasing member.
Providing a protrusion for engaging the second biasing member allows placing the second biasing member adjacent to the clamping element, which may allow a particularly compact construction of the clamping system.
The second biasing member may extend substantially parallel to the clamping element.
In yet another embodiment of the clamping system, the clamping system further comprises a second stop for limiting movement of the clamping element beyond its second position.
Limiting the movement of the clamping element beyond the second position aids in preventing damage to the second biasing means, for instance by preventing overextension or overcompression thereof. Additionally or alternatively the second stop may aid in increasing reliability of the clamping system, by preventing jams that may occur when the clamping element moves beyond the second position.
In yet another embodiment of the clamping system the second stop engages the protrusion in the second position.
Using the protrusion to engage the second stop allows positioning the second stop transversally with respect to the clamping element, so that for instance the actuating member can be positioned in a space corresponding to a longitudinal extension of the clamping element.
In yet another embodiment of the clamping system, the clamping element comprises a recess for receiving at least part of the first biasing member.
The recess forms a cut-out into which the first biasing member may at least partly be received. As a result, the first biasing member and the clamping element may be placed relatively close to each other. In particular, in the second position of the clamping element, a surface of the clamping element for engaging the tool may be relatively close to the first biasing member. As such, the clamping member and the first biasing member together take up less space, allowing a relatively compact construction of the elongate beam.
When the first biasing member is received in the recess, the clamping element may extend at least partly around the first biasing member, i.e. the clamping element may partly surround the first biasing member. The clamping element extending at least partly around the first biasing member may allow the actuating member to engage on a part, e.g. a protrusion, of the clamping element which defines the recess and which in the second position of the clamping element protrudes up to or beyond the first biasing member. The protrusion may aid in providing a relatively large area upon which the actuating member may engage, whereas the recess allows a compact design of the protrusion and the first biasing element.
The recess can further act as a guide for the first biasing member.
In yet another embodiment of the clamping system the first or the second biasing member comprises a compression spring. The recess may therefore correspond to a cylindrical shape of the biasing member.
The applicant has found that using a compression spring allows reliable performance of the clamping system. Moreover, a compression spring can provide sufficient biasing force and requires no external activation.
It should be noted that when compression springs are used, the first cavity and the second cavity may provide the additional advantage that a larger compression spring may be used, thereby allowing a wider choice of compression springs. When using compression springs, the first and second stop may aid in preventing damage or wear to the compression springs.
In yet another embodiment of the clamping system, at least one of the clamping element and the actuating member is provided with an engagement surface for engaging the other of the clamping element and the actuating member, wherein at least a part of the engagement surface is inclined with respect to a direction of movement of the respective element.
Such an inclined engagement surface provides a transmission between the clamping element and the actuating member, so that the clamping element and the actuating member may be placed at an angle with respect to each other, which in turn allows a relatively compact construction of the clamping system.
An angle at which the engagement surface is inclined may be chosen to select a suitable transmission ratio between movement of the actuating member and the clamping element. The angle may even vary, smoothly or abruptly, over the engagement surface, so as to provide a different transmission ratio at different positions of the engagement surface. In particular, the engagement surface may be curved, or comprise two sections with a different angle of inclination.
In yet another embodiment of the clamping system the actuating member comprises a piston of a hydraulic or pneumatic actuation system.
Accordingly, the first biasing member can act directly on said piston, which allows a very direct transfer of force from the first biasing member onto the respective hydraulic or pneumatic fluid.
In yet another embodiment of the clamping system the actuating member extends at least partly in a third cavity in the elongate beam.
By providing a cavity in the elongate beam for the actuating member, the clamping system may be constructed compactly.
Said cavity in the elongate beam is referred to as third cavity only to distinguish it from the first and second cavities. Thus, it is not implied or excluded there is more than one cavity in the elongate beam by usage of the word ‘third’. The first and/or second and/or third cavities need not have anything in common apart from being cavities in their respective parts.
In yet another embodiment of the clamping system the third cavity is integrally formed in the elongate beam.
Integrally forming the cavity in the elongate beam prevents the need for a separate part for the cavity, which would have to be fixed and sealed against the elongate beam. As such a seal may present a risk of leaking or failing, the integrally formed third cavity reduces the probability of leaking or failing. Moreover, the separate part would introduce an additional source of error in mutually positioning parts of the press brake, in particular in positioning the cavity with respect to the clamping element.
Additionally or alternatively, forming the cavity integrally in the elongate beam may make production of the clamping system more cost efficient.
The invention also relates to a press brake comprising at least one clamping system as described above. The clamping system may have any of the above-described features, alone or in any suitable combination.
The clamping system may be arranged in a top beam of the press brake, in a bottom beam of the press brake, or in both. The clamping system may be a separate, exchangeable clamping system, often referred to into the art as clamping beam, or may be an integral part of the press brake.
The invention will be further elucidated with reference to the attached drawings, in which:
In the figures, like elements are referred to with like reference numerals. Corresponding elements of different embodiments are referred to with reference numerals increased by a multiple of one hundred (100).
The actuating member 211 is movably arranged in a pressure chamber 217. The pressure chamber 217 is made directly into the elongate beam 209, which also has the receiving space 210. The pressure chamber 217 is thus integrally formed in the elongate beam 209. The actuating member 211 is provided with sealing means 218 which seal the actuating member 211 to the wall of the pressure chamber 217, i.e. to the inside of the elongate beam 209. As such, the actuating member 211 works as a piston moveable in the pressure chamber 217, which accordingly works as a cylinder. Accordingly, the actuating member 211 can be pushed towards its active position by introducing a fluid in the pressure chamber 217. The pressure chamber 217 of this clamping system 204 is adapted for receiving a hydraulic liquid as pressure fluid, in order to move the actuating member 211.
The clamping system 204 is provided with a first biasing member in the form of a first compression spring 219. The first compression spring acts on the actuating member 211. The first compression spring 219 is arranged vertically, which corresponds to the pressing direction P defined by the clamping system 204, and the depth direction of the receiving space 210. The first compression spring 219 biases the actuating member 211 upwards, i.e. towards its inactive position. Accordingly, when pressure of the hydraulic liquid in the pressure chamber 217 is stopped, the first compression spring 219 pushes the actuating member 211 upwards further into the pressure chamber 217 thereby forcing the hydraulic fluid to flow out of the pressure chamber 217. The first compression spring 219 supports on a support 220 provided by a cover 221. The cover 221 covers clamping element 212, the actuating member 211 and the pressure chamber 217. The cover 221 also forms a first stop 222 for the actuating member 211 to hit, in order to limit movement of the actuating member 211 beyond the active position. The actuating member 211 has a movement limiter 223 for engaging the first stop 222. The first compression spring 219 extends partly in a first cavity 224 in the actuating member 211. A second biasing member is provided in the form of a second compression spring 225. The second compression spring 225 is arranged horizontally, i.e. perpendicular to the pressing direction P and a longitudinal direction of the elongate beam 204. The second compression spring 225 acts on the clamping element 212 via a protrusion 226 thereof. the first compression spring 225 extends partly in a second cavity 227 in the elongate beam. The cover 221 also provides a second stop 228 for engaging the protrusion 226 of the clamping element 212, to limit the movement of the clamping element 212 beyond its second position.
Obviously, the bottom clamping system 706 could be altered by applying any of the features described above, such as the separate elongate beam and/or the separate cylinder in the cavity and/or the hose as a pressure chamber.
Although the invention has been described hereabove with reference to a number of specific examples and embodiments, the invention is not limited thereto. Instead, the invention also covers the subject matter defined by the claims, which now follow.
Number | Date | Country | Kind |
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2026128 | Jul 2020 | NL | national |
Filing Document | Filing Date | Country | Kind |
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PCT/NL2021/050448 | 7/16/2021 | WO |