WO2011070231A1

WO2011070231A1 - Press brake

Info

Publication number: WO2011070231A1
Application number: PCT/FI2010/050970
Authority: WO
Inventors: Hannu Alitalo
Original assignee: Aliko Automation Oy
Priority date: 2009-12-11
Filing date: 2010-11-29
Publication date: 2011-06-16
Also published as: RU2012126404A; EP2509782A4; EP2509782A1

Abstract

A press brake, wherein the lower beam (3) and/or the upper beam (4), which are structural assemblies that can be assembled from separate parts, include a frame beam (9), wherein an edging tool can be supported on the horizontal edge (R) of a long side thereof. The lower beam (3) and/or the upper beam (4) include a force distribution system comprising at least one pair of oblique tensile bars (12, 13; 14, 15) connected by connections (20, 21, 23, 24, 25, 26, 27, 28, 31, 33, 36, 38) that form force node points relative to the frame beam (9) and adapted to transmit and distribute a press force provided by press cylinders (5, 7) to the desired locations determined by the locations of the connections in the desired power distribution ratio throughout the edging length of the frame beam (9) in order to keep the edge (R) of the frame beam straight.

Description

PRESS BRAKE

FIELD OF THE INVENTION The invention relates to the press brake defined in the preamble of claim 1.

BACKGROUND OF THE INVENTION In an edging process the edging accuracy must be good in order to provide a good end product, i.e. the bend^¬ ing angle must be accurate and of the same degree throughout the length of the plate. This means that both the table of the lower beam (on which the lower tool is disposed) and the upper beam (to which the upper tool is mounted) must be exactly parallel throughout the edging length during bending.

In press brakes where press cylinders act at the ends of the upper beam the load situation is as shown in Fig. la. A downward applied press force F acts at the ends of the upper beam 4, and an opposite support reaction is constituted throughout the length of the upper beam by an upward applied continuous load Fk originat- ing from the lower beam 3 via edging tools and the plate to be bent. In this case, the upper beam 4 bends upwards. Respectively, the load situation of the lower beam 3 is as shown in Fig. lb. The lower beam 3 is supported on the faces at each end and is subject to the downward applied continuous load Fk from the upper beam 4 via tools and the plate to be bent. In this case, the lower beam 3 bends downward. If attempts were not made in order to compensate for these bends, the bending angle of a long plate to be bent would become larger in the middle than at the ends of the plate. Known from the patent literature are a number of different solutions in order to realize the bending compensation. Known from publications US 3,914,975, EP 1 452 302 Bl, US 6519996, WO 82/02360, WO 2008/049796 Al, EP 1769857 A2 are bending compensation arrangements in order to improve the edging accuracy. A purpose of the arrangements is to compensate for the concave upward bending of the upper beam and/or the downward bending of the lower beam and to keep the tools paral- lei. The publications disclose different solutions utilizing hydraulic cylinders, so-called crowning cylinders, that , act on the lower beam and/or the upper beam in order to provide the above-mentioned compensation effect.

In addition, it is known that crowning is most generally carried out by different hydraulic cylinders or wedge arrangements that act on the table of the lower beam (such as e.g. US 4,732,032, US 6,725,702).

Using the above-mentioned prior art, the upper and/or the lower beam in large press brakes (for example where the edging length may be on the order . of more than 10 to 15 meters and the press force on the order of 600t to 4000t) should be provided with massively large-sized crowning cylinders with a large cross-sectional area and short stroke length (the necessary stroke being on the order of less than 10 mm) in order to provide the necessary crowning forces to provide bending compensa- tion. A problem is that, during edging, a very high pressure may develop in such cylinders (a pressure of up to 600 bars has been verified in experiments) , which, when repeated, damages the crowning cylinders and shortens their service life. In practice, the rwon- ing cylinders have not coped, but have been broken down. Furthermore, a problem in large-sized crowning cylinders is that, because of their great need for space, they provide restrictions to the bending angle.

It is further known from the prior art that generally the upper beam and the lower beam of a press brake are conventionally made as a monolithic structure welded from thick steel sheets.

Especially in the case of very large press brakes it becomes problematic that the welded seams are large, and the large and heavy pieces are difficult to handle and transport. As an example, in the largest press brakes the mass of the upper beam provided as a monolithic part may be up to 200t. The height of such a massively structured upper beam may be e.g. 6 meters. Oversize transports have been necessary to deliver the items. The load ratings in roads and bridges and clearances below bridges and electric and telephone wires etc. become problematic. The sheet dimensions are spe- cial dimensions, and there are only few manufacturers therefor, so parts for press brakes become expensive and the delivery time may be months.

OBJECTIVE OF THE INVENTION

An objective of the invention is to eliminate the drawbacks referred to above.

Especially, an objective of the invention is to dis- close a press brake where the edge of the frame beam on which the tool is mounted can be kept straight during edging and where good edging accuracy can be provided regardless of the edging bend length. Furthermore, an objective is to disclose a press brake that can be assembled from parts and that provides for the reduction of size and mass of the individual parts of the upper beam and the lower beam, in which case the handling, storage, packing for transportation, transportation to installation site and assembling at the installation site become easier and the costs are reduced.

Yet another objective of the invention is to disclose a press brake where the magnitude of the forces to be ap- plied on the frame beam in order to keep it straight can be adjusted during the bending and the maximum load.

SUMMARY OF THE INVENTION

The press brake according to the invention is characterized by what has been presented in claim 1.

According to the invention the lower beam and/or the upper beam, which are structural assemblies that can be assembled from separate parts, include a frame beam, wherein the edging tool can be supported on the horizontal edge of the long side thereof. The lower beam and/or the upper beam include a force distribution sys- tern comprising at least one pair of obligue tensile bars connected by connections that form force node points relative to the frame beam and being adapted to transmit and distribute the press force provided by press cylinders to desired locations determined by the locations of the connections in a desired force distribution ratio throughout the edging length of the frame beam in order to keep the edge of the frame beam straight . An advantage of the invention is that the edge of the frame . beam can be kept straight throughout the edging process, providing for high edging accuracy throughout the bending length of the plate to be bent, i.e. the bending angle of the plate is the same and correct throughout the bending length. The force provided by press cylinders that provide a stroke of the upper beam of the press brake can be utilized in order to generate the forces necessary to keep the frame beam straight. The fact that the lower beam and/or the upper beam are formed from separate parts provides for the possibility to reduce the size and mass of the parts of the upper beam and the lower beam, so that the handling, storage, packing for transportation, transportation to installation site and assembly at the installation site become ^■ easier and the costs are reduced. The parts may be transported for example in freight containers, and oversize transports are not necessary. It is also possible to provide the connections that form the force node points with force means in order to adjust the press force to be applied on the frame beam over the length thereof at the locations determined by the force node points, either before or during the press brake process .

In one embodiment of the press brake the frame beam has a first end and a second end. The force distribution system includes one or more pairs of oblique tensile bars, the oblique tensile, bars of each pair being similar to each other as mirror images, each pair being provided symmetrically relative to the vertical symme- try center line of the frame beam in a V-shape configuration relative to each other and disposed at equal angles relative to the symmetry center line, so that each oblique tensile bar has an adjacent end relative to the frame beam and a farther end relative to the frame beam. The adjacent end relative to the frame beam of a first oblique tensile bar of at least one pair of oblique tensile bars is connected to the first end of the frame beam by a first connection that forms a force node point. Respectively, the adjacent end relative to the frame beam of a second oblique tensile bar of the pair of oblique tensile bars is connected to the second end of the frame beam by a second connection that forms a force node point on the same horizontal first plane with the first connection. On the upper beam a first press cylinder is connected to the adjacent end rela- tive to the frame beam of the first oblique tensile bar at a mounting point that is vertically spaced apart from the first connection and disposed on the same vertical plane with the first connection. Respectively, a second press cylinder that acts on the upper beam is connected to the adjacent end relative to the frame beam of the second oblique tensile bar at a mounting point that is vertically spaced apart from the second connection and disposed on the same vertical plane with the second connection. Furthermore, the force distribu- tion system includes a frame part which is a part made of monolithic material with the frame beam or mounted as a separate part relative to the frame beam, being vertically spaced apart from the frame beam. The frame part has a third connection that forms a force node point between the frame part and the first oblique tensile bar in order to connect the farther end relative to the frame beam of the first oblique tensile bar to the frame part. In addition, the frame part has a fourth connection that forms a force node point between the frame part and the second oblique tensile bar on the same horizontal second plane with the third connection in order to connect the farther end relative to the frame beam of the second oblique tensile bar to the frame part by the fourth connection, so that the third connection and the fourth connection are disposed on vertical planes at the same first distance from the vertical symmetry center line of the frame beam on both sides thereof. The forces in the press brake process are distributed via the oblique tensile bars and the force node points formed by said connections over the length of the frame beam on the locations of the planes that pass substantially via said connections in the vertical direction relative to the frame beam, generating vertical press forces on the structure that produce local forces at said locations of the frame beam, keep- ing the edge of the frame beam straight during pressing throughout the edging length.

In one embodiment of the press brake the first oblique tensile bar is detachably connected fixedly relative to the frame beam by a fifth connection that forms a force node point therebetween and is diposed between the first connection and the third connection. The second oblique tensile bar is detachably fixedly connected relative to the frame beam by a sixth connection that forms a force node point therebetween and is disposed between the second connection and the fourth connection on the same horizontal third plane with the fifth connection, so that the fifth connection and the sixth connection are disposed on vertical planes at the same second distance that is greater than the first distance from the vertical symmetry center line of the frame beam on both sides thereof.

In one embodiment of the press brake the first oblique tensile bar is detachably fixedly connected relative to the frame beam by a seventh connection that forms a force node point therebetween and is disposed between the first connection and the fifth connection. The second oblique tensile bar is detachably fixedly connected relative to the frame beam by an eighth connection that forms a force node point therebetween and is disposed between the second connection and the sixth connection on the same horizontal fourth plane with the seventh connection, so that the seventh connection and the eighth connection are disposed on vertical planes at the same third distance that is greater than the second distance from the vertical symmetry center line of the frame beam on both sides thereof.

In one embodiment of the press brake the lower beam and/or the upper beam include frame plates provided adjacently one on the other and mounted by weld or bolted connections to each other and to the frame beam.

In one embodiment of the press brake the thickness of the frame plates is substantially smaller than the thickness of the frame beam.

In one embodiment of the press brake the force distribution system includes two pairs of oblique tensile bars including a first pair of oblique tensile bars formed by said first oblique tensile bar and second oblique tensile bar, and a second pair of oblique tensile bars formed by a third oblique tensile bar and a fourth oblique tensile bar. The third and the fourth oblique tensile bar are provided in V-shape relative to each other within the V-shape formed by the first pair of oblique tensile bars jointly, so that the adjacent end relative to the frame beam of the third oblique tensile bar is connected to the frame part adjacent to the frame beam in the vicinity of the first end by a ninth connection that forms a force node point and, respectively, the adjacent end relative to the frame beam of the fourth oblique tensile bar of the second pair of oblique tensile bars is connected to the frame part ad- jacent to the frame beam in the vicinity of the second end by a tenth connection that forms a force node point on the same horizontal fifth plane with the ninth connection. The farther end relative to the frame beam of the third oblique tensile bar is connected to the frame part by an eleventh connection that forms a force node point. The farther end relative to the frame beam of the fourth oblique tensile bar is connected to the frame part by a twelwth connection that forms a force node point. The twelfth connection that forms a force node point between the frame part and the fourth oblique tensile bar is disposed on the same horizontal sixth plane with the eleventh connection, and the eleventh connection and the twelfth connection are disposed on vertical planes at the same fourth distance from the vertical symmetry center line of the frame beam on both sides thereof. The fourth distance is smaller than the first distance. In this case the force node points formed by the ninth connection, tenth connection, eleventh connection and twelfth connection generate vertical press forces on the structure, producing local forces on said locations of the frame beam in order to keep the edge of the frame beam straight during pressing .

In one embodiment of the press brake the ninth connec- tion is disposed on the same vertical plane with the fifth connection and the tenth connection is disposed on the same vertical plane with the sixth connection.

In one embodiment of the press brake the connections that form the force node points include mortise and tenon connections.

In one embodiment of the press brake the first connection and the second connection are mortise and tenon connections. Also, the ninth and the tenth connection are mortise and tenon connections. In one embodiment of the press brake the force distribution system includes force means adapted to generate tensional stress on the oblique tensile bars in order to apply vertical press force on the frame beam.

In one embodiment of the press brake the force means are adapted to prestress an internal stress state of a predetermined degree on the upper and/or the lower beam assembly before the press brake process in order to bend the frame beam convex, which is then straightened in the press brake process.

In one embodiment of the press brake the force means are adapted actively to adjust the stress state of the upper and/or the lower beam assembly in order to keep straightness deviation of the frame beam lower than a predetermined straightness deviation throughout the edging process.

In one embodiment of the press brake the first connection, the second connection, the third connection and the fourth connection are provided with force means adapted to adjust the tensional stress of the tensile bar synchronically relative to each other and/or individually.

In one embodiment of the press brake the fifth connection and the sixth connection are provided with force means adapted to adjust the tensional stress of the tensile bar synchronically relative to each other and/or individually.

In one embodiment of the press brake the seventh connection and the eighth connection are provided with force means adapted to adjust the tensional stress of the tensile bar synchronically relative to each other and/or individually.

In one embodiment of the press brake the eleventh con- nection and the twelfth connection are provided with force means adapted to adjust the tensional stress of the tensile bar synchronically relative to each other and/or individually. In one embodiment of the press brake a vertical post is provided on the center line between the frame part and the frame beam and mounted at the first end to the frame beam and connected at the second end to the frame part by a thirteenth connection that forms a force node point and is disposed on said center line. The thirteenth connection is provided with a force means adapted to generate a press force to the middle of the frame beam through the vertical post. In one embodiment of the press brake the force means includes a cam mechanism.

In one embodiment of the press brake the cam mechanism includes a rotating shaft including a round shaft part adapted to rotate in a first hole in a first component; a round cam which is eccentric relative to the shaft part and adapted to rotate in a second hole in a second component adjacent to the first component; and a hydraulic cylinder is adapted to rotate the rotating shaft.

In one embodiment of the press brake the cam mechanism includes a bent lever mounted to the rotating shaft. The hydraulic cylinder is adapted to turn the bent lever in order to rotate the rotating shaft. In one embodiment of the press brake the force means are hydraulic press cylinders adapted directly or indirectly to act between a connection that forms a force node point and the frame beam in order to generate a tensional force applied on the tensile bars and a press force applied on the frame beam.

In one embodiment of the press brake a set of vertically extending posts is mounted on the frame beam, connections that form force node points being formed at the ends of the posts. A press cylinder is fitted at the upper or lower end of each post. The force distribution system of the lower beam and/or the upper beam includes horizontal tensile bars, each of which is con- nected between each two connections on the same horizontal plane.

In one embodiment of the press brake the oblique tensile bar includes two slots extending in the lengthwise direction of the oblique tensile bar in parallel relative to each other.

LIST OF FIGURES In the following section the invention will be described in detail by means of exemplifying embodiments, with reference to the accompanying drawing in which

Fig. la presents a load situation of an upper beam dur- ing a press brake process and, presented as a broken line, the tendency of the upper beam to bend upward to a concave shape,

Fig. lb presents a . load situation of a lower beam dur- ing a press brake process and, presented as a broken line, the tendency of the lower beam to bend downward to a concave shape,

Fig. 2 axonometrically presents a first embodiment of the press brake according to the invention as seen obliquely from above and having the so-called A-faces,

Fig. 3 axonometrically presents a second embodiment of the press brake according to the invention as seen obliquely from above and having the so-called C-faces,

Fig. 4 presents, as a plane view, an upper beam of a third embodiment of the press brake according to the invention,

Fig. 5 presents, as a plane view, a lower beam of a third embodiment of the press brake according to the invention, Fig., 6 schematically presents internal stresses on the upper beam of Fig. 4 when tension is applied on the oblique tensile bars at the force node points,

Fig. 7 schematically presents the upper beam of Fig. 6 and the tensions therein during a press brake process,

Fig. 8 presents, as an exploded view seen obliquely from avobe, the upper beam of Fig. 4 and 6, Fig. 9 presents, as an exploded view seen obliquely from above, the lower beam of Fig. 5,

Fig. 10 presents, as an exploded view seen obliquely from above, the frame beam of the upper beam of Fig. 8 and the frame parts to be connected thereto, Fig. 11 presents, as an exploded view seen obliquely from above, the frame beam of the lower beam of Fig. 9 and the frame parts to be connected thereto,

Fig. 12 presents, as a plane view, an upper beam of a fourth embodiment of the press brake according to the invention,

Fig. 13 presents, as a plane view, a lower beam of a fourth embodiment of the press brake according to the invention,

Fig. 14 presents, as an exploded view seen obliquely from above, the lower beam of Fig. 12,

Fig. 15 presents, as an exploded view seen obliquely from above, the lower beam of Fig. 13,

Fig. 16 presents, as a plane view, an upper beam of a fifth embodiment of the press brake according to the invention as seen in a position of use from the front,

Fig. 17 presents the upper beam of Fig. 16 as seen in a position of use from the back,

Fig. 18 presents, as an exploded view seen obliquely from above, the upper beam of Fig. 16 and 17,

Fig. 19 presents detail A from Fig. 6 in a situation where a cam of a cam mechanism that operates as a force means that acts on a node point has not been turned,

Fig. 20 presents detail A from Fig. 6 in a situation where a cam of a cam mechanism that operates as a force means that acts on a node point has been turned, Fig. 21 presents section XXI-XXI of Fig. 19,

Fig. 22 presents section XXII-XXII of Fig. 20, Fig. 23 presents, as a plane view, an upper beam of a sixth embodiment of the press brake according to the invention,

Fig. 24 presents, as an exploded view seen obliquely from above, the upper beam of Fig. 23,

Fig. 25 presents, as a plane view, an upper beam of a seventh embodiment of the press brake according to the invention,

Fig. 26 presents, as an exploded view seen obliquely from above, the upper beam of Fig. 25,

Fig. 27 presents, as a plane view, an upper beam of an eighth embodiment of the press brake according to the invention, and

Fig. 28 presents, as an exploded view seen obliquely from above, the upper beam of Fig. 27.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 2 and 3 both present a press brake including a first face 1 and a second face 2 at the ends of the press brake, supporting the press brake on the floor. A lower beam 3 is supported to be stationary on the first face 1 and on the second face 2. The lower beam 3 has a table T on which a lower edging tool (not shown) is mountable. An upper beam 4 is supported on the first face 1 and the second face 2 to be moved vertically relative to the lower beam 3. An upper edging tool (not shown) is mountable on the upper beam.

A first press cylinder 5 is fitted between the first face 1 and a first end 6 of the upper beam 4 in order to provide the press brake movement and force of the upper beam, and a second press cylinder 7 that is simi^¬ lar to the first press cylinder is fitted between the second face 2 and a second end 8 of the upper beam 4 in order to provide the press brake movement and force of the upper beam 4 synchronically with the first press cylinder .

It is characteristic of the embodiments of the upper and the lower beam presented in Fig. 2 to 28 that the lower beam 3 and/or the upper beam 4 are structural assemblies mountable from separate parts. They all include an elongated frame beam 9, wherein the edging tool can be supported on the horizontal edge R of the long side thereof, which is the lower edge on the upper beam and table T on top of the upper edge on the lower beam. The lower beam 3 and the upper beam 4 both in^¬ clude a force distribution system comprising at least one pair of oblique tensile bars 12, 13; 14, 15 con- nected by connections 20, 21, 23, 24, 25, 26, 27, 28, 31, 33, 36, 38 that form force node points relative to the frame beam 9 and being adapted to transmit and distribute the press force provided by the press cylinders 5, 7 to the desired locations determined by the loca- tions of the connections in the desired power distribution ratio throughout the edging length of the frame beam 9 in order to keep the edge R of the frame beam straight . With reference to Fig. 4 and 5, the features shared by all the different embodiments of the invention pre- sented by Fig. 4, 5, 12, 13, 16, 23, 25 and 27 are now described in detail.

Fig. 4 and 5, exploded views 8 and 9, as well as 10 and 11 present embodiments of the upper beam 4 and the lower beam 3 that are substantially similar in structure. In both of them, the force distribution system includes a pair of oblique tensile bars 12, 13. The oblique tensile bars 12 and 13 are similar to each other as mirror images relative to the vertical symmetry center line L - L of the frame beam. The oblique tensile bars 12 and 13 are disposed symmetrically relative to the vertical symmetry center line L - L of the frame beam in a V- shape configuration relative to each other at the same angle a relative to the symmetry center line L - L. The V-angle opens toward the frame beam 9. Both oblique tensile bars 12, 13 have an adjacent end 16, 17 relative to the frame beam and a farther end 18, 19 relative to the frame beam. The adjacent end 16 relative to the frame beam of the first oblique tensile bar 12 is connected to the first end 10 of the frame beam by a first connection 20 that forms a force node point. Respectively, the adjacent end 17 relative to the frame beam of the second oblique tensile bar 13 of the pair of oblique tensile bars is connected to the second end 11 of the frame beam by a second connection 21 that forms a force node point on the same horizontal first plane χχ - xi with the first connection 20. On the upper beam 4 a first press cylinder 5 is connected to the adjacent end 16 relative to the frame beam of the first oblique tensile bar 12 at a mounting point 100 that is vertically spaced apart from the first connection 20 on the same vertical plane Yi - Yi with the first connection 20. A second press cylinder 7 is connected to the adjacent end 17 relative to the frame beam of the second oblique tensile bar 13 at a mounting point 200 that is vertically spaced apart from the second connection 21 on the same vertical plane Y₂ - Y₂ with the second connection 21.

The upper beam 4 and the lower beam include a frame part 22 that may be part of the same monolithic material with the frame beam 9, especially in small press brakes. In large press brakes the frame part 22 is preferably mounted as a separate part relative to the frame beam 9. The frame part 22 is vertically spaced apart from the frame beam 9.

The frame part 22 has a third connection 23 in order to connect the farther end 18 relative to the frame beam of the first oblique tensile bar 12 to the frame part 22, the third connection 23 forming a force node point between the frame part 22 and the first oblique tensile bar 12. Furthermore, the frame part 22 has a fourth connection 24 that forms a force node point between the frame part 22 and the second oblique tensile bar 13 on the same horizontal second plane x₂ - x₂ with the third connection 23. By the fourth connection 24 the farther end 19 relative to the frame beam of the second oblique tensile bar 13 is connected to the frame part 22, so that the third connection 23 and the fourth connection 24 are disposed on vertical planes y_x - y_lf y₂ - y₂ at the same first distance si from the vertical symmetry center line L - L of the frame beam on both sides thereof.

With further reference to Fig. 4 and 5, the first oblique tensile bar 12 is detachably connected fixedly relative to the frame beam 9 by a fifth connection 25 that forms a force node point therebetween and is disposed between the first connection 20 and the third connection 23. Respectively, the second oblique tensile bar 13 is detachably fixedly connected relative to the frame beam 9 by a sixth connection 26 that forms a force node point therebetween and is disposed between the second connection 21 and the fourth connection 24 on the same horizontal third plane 3 - x₃ with the fifth connection 25. In addition, the fifth connection 25 and the sixth connection 26 are disposed on vertical planes Y3 - Y3r Yi - Y4 ^at the same second distance s₂ that is greater than the first distance si from the vertical symmetry center line L - L of the frame beam on both sides thereof.

With further reference to Fig. 4 and 5, the first oblique tensile bar 12 is detachably fixedly connected relative to the frame beam 9 by a seventh connection 27 that forms a force node point therebetween and is disposed between the first connection 20 and the fifth connection 25. Respectively, the second oblique tensile bar 13 is detachably fixedly connected relative to the frame beam by an eighth connection 28 that forms a force node point therebetween and is disposed between the second connection 21 and the sixth connection 26 on the same horizontal fourth plane x₄ - X4 with the seventh connection 27, so that the seventh connection 27 and the eighth connection 28 are disposed on vertical planes ys - y₅, y<s - Ye at the same third distance S3 that is greater than the second distance s₂ from the vertical symmetry center line L - L of the frame beam on both sides thereof.

The lower beam 3 and the upper beam 4 include frame plates 29' , 29" provided adjacently one on the other and mounted by weld connections or bolted connections 30 to each other and to the frame beam 9. The thickness of the frame plates 29' , 29" may be smaller than the thickness of the frame beam 9.

The oblique tensile bars 12, 13 both include two slots 51 extending in the lengthwise direction thereof in parallel to each other. On the first oblique tensile bar 12 the slots 51 are provided on both sides of the fifth connection 25 so as to extend up- and downward therefrom in the lengthwise direction. Respectively, the second oblique tensile bar 13 includes two slots 51, respectively extending in the lengthwise direction thereof in parallel to each other and provided on both sides of the sixth connection 26 so as to extend up- and downward therefrom in the lengthwise direction. The slots 51 allow the oblique tensile bar 12, resp. 13, slightly to bend sideward at the isthmus that remains between the slots 51 at the connection 25, resp. 26.

The force distribution system being provided in the above-mention manner, the forces in the press brake process are distributed via the oblique tensile bars 12, 13 and the force node points formed by said connections 20, 21, 23, 24, 25, 26, 27, 28 over the length of the frame beam on the planes Yi - Yi; yi _ yi, y₂ - y2_; y3 - y₃, y₄ - y₄, y₅ - y₅, y₆ - y₆, Y₂ - Y₂ that pass substantially via said connections in the vertical direction relative to the frame beam, generating vertical press forces on the structure that produce local forces on the vertical planes on the frame beam 9, keeping the edge R of the frame beam straight during pressing throughout the edging length.

The force distribution system additionally includes force means 39 adapted to generate tensional stress on the oblique tensile bars 12, 13 as necessary. In the embodiment of Fig. 4 and 5 the force means 39 are formed by cam mechanisms 40 provided on the third connection 23, fourth connection 24, fifth connection 25, sixth connection 26, seventh connection 27 and eighth connection 28. The first connection 20 and the second connection 21 are herein simple mortise and tenon connections, although they could also be provided with a cam mechanism in another embodiment. The structure and operation of the cam mechanism 40 is described in more detail above in connection with Fig. 19 to 22. The cam mechanisms of each connection on the same horizontal plane are arranged to act synchronically relative to each other. Also, their individual adjustment is possible.

By the cam mechanism 40 the upper beam and the lower beam can be prestressed before the press brake process so as to develop a stress state of a predetermined degree in order to bend the frame beam convex, which is then straightened in the press brake process. The stress state generated by prestressing is illustrated in Fig. 6 by the upper beam in presenting the forces acting thereon and the internal force lines developing on the upper beam as tension and pressure lines depicted by the symbols. Tension is presented by symbol - >->-> and pressure by symbol <><><><>. The corresponding takes place on the lower beam. Fig. 7 illustrates the situation of the upper beam when it is subject to full edging force.

In addition to prestressing, the stress state of the upper and the lower beam can be actively adjusted by the cam mechanisms 40 during the press brake process in order to keep the edge of the frame beam straight throughout the edging process. With reference to Fig. 7 the force F of the press brake cylinders acts on the connections 100 and 200 of the oblique tensile bars 12 and 13, i.e. the force is applied only on the oblique tensile bars 12 and 13. The force is transmitted via the oblique tensile bars 12, 13 to connections 20 and 21, via which the force is distributed further through the oblique tensile bars 12, 13 to the node points formed by connections 23, 24, 25, 26, 27, 28 and via them to the frame beam 9 as ver- tical reactions. At the node points, the force is adjusted by the cam mechanisms 40 to different locations of the frame beam. The continuous load along the tool length applied on the edging tool is compensated for by the above-mentioned vertical reactions. The side ten- sile bars 12 and 13, frame part 22 and frame plates 29' , 29" form a reaction pattern via the force node points across the entire beam, providing for vertical application of pressure on the frame beam. Because only press force is applied vertically on the frame structure, it may be divided vertically in different parts as shown in Fig. 4 and 5 and especially in Fig. 10 and 11. The purpose of the force distribution system is not crowning, i.e. bending, the frame beam, but transmitting the force by the oblique tensile bars 12, 13 and the force node points to the frame beam 9 to the extent that it remains straight during the press brake process throughout the edging length, or, if the plate to be edged has to be pressed more at a specific location, for example due to variation of hardness of the plate material, by adjusting the cam mechanism 40 (or by other force means 39 in another embodiment) the frame beam 9 may be pressed more at a specific location by adding force to that specific location. Fig. 12 and 13 as well as exploded views 14 and 15 present the upper beam 4 and the lower beam 3, wherein the force distribution system otherwise corresponds to the embodiments of Fig. 4 and 5, except that in the embodiments of Fig. 12 and 13 the force distribution system includes two pairs of oblique tensile bars 12, 13; 14, 15 including a first pair of oblique tensile bars 12, 13 formed by said first oblique tensile bar 12 and sec- ond oblique tensile bar 13, wherein the connections correspond to those described in connection with Fig. 4 and 5, so reference is made to the description of Fig. 4 and 5 for that part. The second pair of oblique tensile bars 14, 15 is formed by a third oblique tensile bar 14 and a fourth oblique tensile bar 15 provided in V-shape relative to each other opening toward the frame beam 9 within the V-shape formed by the first pair of oblique tensile bars 12, 13 jointly. The third oblique tensile bar 14 and the fourth oblique tensile bar 15 are disposed at the same angle β relative to the symmetry center line L - L on both sides thereof. The adjacent end 31 relative to the frame beam of the third oblique tensile bar 14 is connected to the frame part 29' adjacent to the frame beam in the vicinity of the first end 10 by a ninth connection 32 that forms a force node point and, respctively, the adjacent end 33 relative to the frame beam of the fourth oblique tensile bar 15 of the second pair of oblique tensile bars is connected to the frame part 29' adjacent to the frame beam in the vicinity of the second end 11 by a tenth connection 34 that forms a force node point on the same horizontal fifth plane X5 - x₅ with the ninth connection 32. The farther end 35 relative to the frame beam of the third oblique tensile bar 14 is connected to the frame part 22 by an eleventh connection 36 that forms a force node point. The farther end 37 relative to the frame beam of the fourth oblique tensile bar 15 is connected to the frame part 20 by a twelfth connection 38 that forms a force node point. The twelfth connection 38 that forms a force node point between the frame part 22 and the fourth oblique tensile bar 15 is disposed on the same horizontal sixth plane xe - χβ with the eleventh connection 36, and the eleventh connection 36 and the twelfth connection 38 are disposed on vertical planes y₇ - y₇, ye - ys at the same fourth distance s₄ from the vertical symmetry center line L-L of the frame beam on both sides thereof. The fourth distance s₄ is smaller than the first distance Si. The ninth connection 32 is disposed on the same vertical plane Y₃ - Y₃ with the fifth connection 20, and the tenth connection 34 is disposed on the same vertical plane Y₄ - Y₄ with the sixth connection 26.

The force node points formed by the ninth connection 31, tenth connection 34, eleventh connection 36 and twelfth connection 38 generate vertical press forces on the structure, producing local forces on the frame beam 9 at said locations in order to keep the edge of the frame beam straight during pressing. This way, vertical reactions on the frame beam 9 can be increased over the middle area of the frame beam 9 on vertical planes y₇ - y₇, ys - ys in order to keep it straight.

The eleventh connection 36 and the twelfth connection 38 are provided with force means 39 which here, too, are cam mechanisms 40 in order to adjust the tensional stress of the oblique tensile bars 14, 15 synchronic- ally relative to each other and/or individually. The ninth connection 3.2 and the tenth connection 34 are mortise and tenon connections in this example, but they can also be provided with, cam mechanisms 40. Fig. 16 and 17 as well as exploded view 18 present yet one embodiment of the upper beam . The lower beam may naturally be made with the same structure. The force distribution system of the upper beam of Fig. 16 and 17 otherwise corresponds to the upper beam of Fig. 4, ex- cept that in the embodiment of Fig. 16 and 17 a vertical post 52 has been added to the force distribution system, to the middle area between the frame part 22 and the frame beam 9, on the center line L - L, and mounted at the first end to the frame beam 9 and con- nected at the second end to the frame part 22 by a thirteenth connection 53 that forms a force node point, the thirteenth connection 53 being disposed on said center line L - L. The thirteenth connection 53 is provided with a force means 39, a cam mechanism 40 in this example, adapted to generate a press force through the vertical post to the middle of the frame beam .9 on the center line L - L.

Fig. 19 and 20 show enlarged detail A from Fig. 6 il- lustrating the cam mechanism 40 provided at the force node point formed by connection 24. Preferably the cam mechanism 40 is similar in each connection on which it is mounted. In Fig. 19 the cam mechanism 40 is disposed in a position where the stress on the force node point is nil. In Fig. 20 the cam mechanism 40 is disposed in a position where the stress on the force node point is at the maximum.

The cam mechanism includes a rotating shaft 41 includ- ing a round shaft part 42 and a round cam 44. The shaft part 42 is adapted to rotate in a first hole 43 on the oblique tensile bar 13. Adjacent to the round shaft part 42 is a round cam 44 which is eccentric relative to the shaft part 42. The cam 42 is adapted to rotate in a second hole 45 on the frame part 22. Mounted on the rotating shaft 41 is a bent lever 47. A hydraulic cylinder 46 is adapted to turn the bent lever 47 in order to rotate the rotating shaft 41. In Fig. 20 and 22 the hydraulic cylinder 46 has rotated the bent lever for 90°, in which case the cam has rotated in the sec- ond hole 45 to the same extent, in which case the maximum stress is provided on the force node point formed by connection 24 and transmitted as a vertical reaction on the frame beam 9. Fig. 23 and 24 as well as Fig. 25 and 26 present two embodiments of the upper beam which, for the part of the arrangement of the oblique tensile bars 12, 13 and the connections 20, 21, 23, 24, 25, 26, 27, 28 that form the force node points, substantially correspond to the embodiment of Fig. 4, to the description of which reference is made for that part. The presented structure of the upper beam of the figures is also well- suited as the structure of the lower beam. In this embodiment the force means 39 are press cylinders 48 adapted directly or indirectly to act between a connection that forms a force node point and the frame beam 9 in order to generate a tensional force applied on the tensile bars 12, 13 and a press force applied on the frame beam. A set of vertically extending posts 49 is detachably mounted to the frame beam 9, the connections that form the force node points being formed at the ends of the posts. In the embodiments, of Fig. 23 and 24 a press cylinder 48 is fitted at the upper end of each post 49. In the embodiment of Fig. 25 and 26 a press cylinder 48 is fitted at the lower end of each post 49 between the post and the frame beam 9. The force dis- tribution system additionally includes horizontal tensile bars 50' , 50", 50"' , each being connected between each two connections on the same horizontal plane. The embodiment of Fig. 23 and 24 has three horizontal ten- sile bars 50', 50", 50". In the same way, the embodiment of Fig. 25 and 26 has three horizontal tensile bars 50' , 50", 50"' .

Fig. 27 and 29 present yet one embodiment of the upper beam which, for the part of the arrangement of the oblique tensile bars 12, 13 and the connections 20, 21, 23, 24, 25, 26, 27, 28 that form the force node points, substantially corresponds to the embodiment of Fig. -4 provided with the cam mechanism 40, to the description of which reference is made for that part. However, a difference in comparison with the embodiment of Fig. 4 is that the frame plates 29' , 29" are now replaced by vertical posts 49 and two horizontal tensile bars 50' , 50".

The invention is not limited merely to the exemplifying embodiments referred to above; instead, many variations are possible within the scope of the inventive idea defined by the claims.

Claims

1. A press brake, including

- a first face (1) and a second face (2) at the ends of the press brake in order to support the press brake on a fixed base,

- a lower beam (3) supported to be stationary on the first and the second face, to which lower beam a lower edging tool is mountable,

- an upper beam (4) supported on the first and the second face to be moved vertically relative to the lower beam, to which upper beam an upper edging tool is mountable,

- a first press cylinder (5) fitted between the first face (1) and the first end (6) of the upper beam (4) in order to provide the press movement and force of the upper beam, and

- a second press cylinder (7) that is similar to the first press cylinder and fitted between the sec- ond face (2) and the second end (8) of the upper beam (4) in order to provide the press brake movement and force of the upper beam synchronically with the first press cylinder, ch a r a c t e r i z e d in that

the lower beam (3) and/or the upper beam (4), which are structural assemblies mountable from separate parts, include a frame beam (9), wherein the edging tool may be supported on the horizontal edge (R) of the long side thereof; and that the lower beam (3) and/or the upper beam (4) include a force distribution system comprising at least one pair of oblique tensile bars (12, 13; 14, 15) connected by connections (20, 21, 23, 24, 25, 26, 27, 28, 31, 33, 36, 38) that form force node points relative to the frame beam (9) and adapted to transmit and distribute the press force provided by the press cylinders (5, 7) to the desired locations determined by the locations of the connections in the de- sired force distribution ratio throughout the edging length of the frame beam (9) in order to keep the edge (R) of the frame beam straight.

2. The press brake according to claim 1 , ch a r a c t e r i z e d in that the frame beam (9) has a first end (10) and a second end (11); and that the force distribution system includes

- one or more pairs of oblique tensile bars (12, 13; 14, 15), the oblique tensile bars of each pair being similar to each other as mirror images and each pair being provided symmetrically relative to the ver^¬ tical symmetry center line (L - L) of the frame beam and in a V-shaped comfiguration relative to each other at the same angle (α; β) relative to the symmetry center line (L -L) , so that each oblique tensile bar has an adjacent end (16, 17; 31, 33) relative to the frame beam and a farther end (18, 19; 35, 37) relative to the frame beam, and wherein the adjacent end (16) relative to the frame beam of the first oblique tensile bar (12) of at least one pair of oblique tensile bars (12, 13) is connected to the first end (10) of the frame beam by a first connection (20) that forms a force node point and, respectively, the adjacent end (17) relative to the frame beam of the second oblique tensile bar (13) of the pair of oblique tensile bars is connected to the second end (11) of the frame beam by a second connection (21) that forms a force node point on the same horizontal first plane (xi - χχ) with the first connec- tion (20), and in which upper beam (4) the first press cylinder (5) is connected to the adjacent end (16) relative to the frame beam of the first oblique tensile bar (12) at a mounting point (100) that is vertically spaced apart from the first connection (20) on the same vertical plane (Yi - Yi) with the first connection (20) , and the second press cylinder (7) is connected to the adjacent end (17) relative to the frame beam of the second oblique tensile bar (13) at a mounting point (200) that is vertically spaced apart from the second connection (21) on the same vertical plane (Y2 - Y2) with the second connection (21) ,

- a frame part (22), which is part of the same monolithic material with the frame beam (9) or mounted as a separate part relative to the frame beam (9), the frame part (22) being vertically spaced apart from the frame beam (9), and the frame part (22) having

-- a third connection (23) that forms a force node point between the frame part (22) and the first oblique tensile bar (12) in order to connect the farther end (18) relative to the frame beam of the oblique tensile bar (12) to the frame part (22), and

-- a fourth connection (24) that forms a force node point between the frame part (22) and the second oblique tensile bar (13) on the same horizontal second plane (x₂ - x₂) with the third connection (23) in order to connect the farther end (19) relative to the frame beam of the second oblique tensile bar (13) to the frame part (22) by the fourth connection (24)_., so that the third connection (23) and the fourth connection (24) are disposed on vertical planes (yi - yi, y₂ - y₂) at the same first distance (si) from the vertical symmetry center line (L - L) of the frame beam on both sides thereof,

wherein the forces of the press brake process are distributed via the oblique tensile bars (12, 13) and the force node points formed by said connections (20, 21, 23, 24) over the length of the frame beam on planes (YI - YI; yi - y_x, y₂ - y_2; Y2 - Y2) that pass substantially via said connections in the vertical direction relative to the frame beam and generate vertical press forces on the structure, producing local forces on said locations of the frame beam (9), keeping the edge of the frame beam straight throughout the edging length during pressing.

3. The press brake according to claim 2, c h a r a c - t e r i z e d in that the first oblique tensile bar

(12) is detachably connected fixedly relative to the frame beam (9) by a fifth connection (25) that forms a force node point therebetween and is disposed between the first connection (20) and the third connection (23); and that the second oblique tensile bar (13) is detachably fixedly connected relative to the frame beam (9) by a sixth connection (26) that forms a force node point therebetween and is disposed between the second connection (21) and the fourth connection (24) on the same horizontal third plane (x₃ - x₃) with the fifth connection (25) , so that the fifth connection (25) and the sixth connection (26) are disposed on vertical planes (y₃ - Y3r Y - Yn) at the same second distance (S2) that is greater than the first distance (si) from the vertical symmetry center line (L - L) of the frame beam on both sides thereof.

4. The press brake according to claim 2 or 3, c h a r a c t e r i z e d in that the first oblique tensile bar (12) is detachably fixedly connected relative to the frame beam (9) by a seventh connection (27) that forms a force node point therebetween and is disposed between the first connection (20) and the fifth connection (25); and that the second oblique tensile bar (13) is detachably fixedly connected relative to the frame beam by an eighth connection (28) that forms a force node point therebetween and is disposed between the second connection (21) and the sixth connection (26) on the same horizontal fourth plane (x₄ - x₄) with the seventh connection (27), so that the seventh connection (27) and the eighth connection (28) are disposed on vertical planes (ys - ys, y6 - y6) at the same third distance (S3) that is greater than the second distance (s₂) from the vertical symmetry center line (L - L) of the frame beam on both sides thereof.

5. The press brake according any one of claims 1 to 4 , c h a r a c t e r i z e d in that the lower beam (3) and/or the upper beam (4) include frame plates (29', 29") provided adjacently one on the other and mounted by weld connections or bolted connections (30) to each other and to the frame beam (9) .

6. The press brake according to claim 5, ch a r a c t e r i z e d in that the thickness of the frame plates (29' , 29") is substantially smaller than the thickness of the frame beam (9) .

7. The press brake according to claim 5 or 6, c h a r a c t e r i z e d in that the force distribution system includes two pairs of oblique tensile bars (12, 13; 14, 15) , including

- a first pair of oblique tensile bars (12, 13) formed by said first oblique tensile bar (12) and second oblique tensile bar (13), and

- a second pair of oblique tensile bars (14,

15) formed by a third oblique tensile bar (14) and a fourth oblique tensile bar (15) provided in V-shape relative to each other within the V-shape formed by the first pair of oblique tensile bars (12, 13) jointly, so that the adjacent end (31) relative to the frame beam of the third oblique tensile bar (14) is connected to the frame part (29' ) adjacent to the frame beam in the vicinity of the first end (10) by a ninth connection (32) that forms a force node point and, respectively, the adjacent end (33) relative to the frame beam of the fourth oblique tensile bar (15) of the second pair of oblique tensile bars is connected to the frame part (29' ) adjacent to the frame beam in the vicinity of the second end (11) by a tenth connection (34) that forms a force node point on the same horizontal fifth plane (x₅ - x₅) with the ninth connection (32);

that the farther end (35) relative to the frame beam of the third oblique tensile bar (14) is connected to the frame part (22) by an eleventh connection (36) that forms a force node point;

that the farther end (37) relative to the frame beam of the fourth oblique tensile bar (15) is connected to the frame part (20) by a twelfth connection (38) that forms a force node point; and

that the twelfth connection (38) that forms a force node point between the frame part (22) and the fourth oblique tensile bar (15) is disposed on the same horizontal sixth plane (χε - χε) with the eleventh connection (36), and the eleventh connection (36) and the twelfth connection (38) are disposed on vertical planes (y₇ - y₇, yg - yg) at the same fourth distance (s₄) from the vertical symmetry center line (L-L) of the frame beam on both sides thereof, the fourth distance (S4) being smaller than the first distance (si) ,

wherein the force node points formed by the ninth connection (31), tenth connection (34), eleventh connection (36) and twelfth connection (38) generate vertical press forces on the structure, producing local forces on said locations of the frame beam (9) in order to keep the edge of the frame beam straight during pressing.

8. The press brake according to claim 3 and 7, c h a r a c t e r i z e d in that the ninth connection (32) is disposed on the same vertical plane (Y₃ - Y₃) with the fifth connection (20) , and the tenth connec- tion (34) is disposed on the same vertical plane (Y₄ - Y₄) with the sixth connection (26) .

9. The press brake according to any one of claims 1 to 8, c h a r a c t e r i z e d in that the connections (20,

21, 23, 24, 25, 26, 27, 28, 31, 33, 36, 38) that form the force node points include mortise and tenon connections .

10. The press brake according to claim 9, c h a r a c t e r i z e d in that the first connection (20) and the second connection (21) are mortise and tenon connections; and/or that

the ninth connection (32) and the tenth connection (34) are mortise and tenon connections.

11. The press brake according to any one of claims 1 to

10, c h a r a c t e r i z e d in that the force distribution system includes force means (39) adapted to gener- ate tensional stress on the oblique tensile bars (12, 13; 14, 15) in order to apply vertical press force on the frame beam (9) .

12. The press brake according to claim 11, c h a r a c - t e r i z e d in that the force means (39) are adapted to prestress a stress state of a predetermined degree on the upper and/or the lower beam assembly before the press process in order to bend the frame beam to a convexity that is straightened in the press process.

13. The press brake according to claim 11 or 12, c h a r a c t e r i z e d in that the force means (39) are adapted actively to adjust the stress state of the upper and/or the lower beam assembly in order to keep the edge of the frame beam straight throughout the edging process.

14. The press brake according to any one of claims 1 to

13, c h a r a c t e r i z e d in that the first connection (20), the second connection (21), the third con- nection and the fourth connection (24) are provided with force means (39) adapted to adjust the tensional stress of the tensile bar (12, 13) synchronically relative to each other and/or individually.

15. The press brake according to any one of claims 3 to

14, c h a r a c t e r i z e d in that the fifth connection (25) and the sixth connection (26) are provided with force means (39) adapted to adjust the tensional stress of the tensile bar (12, 13) synchronically relative to each other and/or individually.

16. The press brake according to any one of claims 4 to

15, c h a r a c t e r i z e d in that the seventh connection (27) and the eighth connection (28) are provided with force means (39) adapted to adjust the tensional stress of the tensile bar (12, 13) synchronically relative to each other and/or individually.

17. The press brake according to any one of claims 7 to 16, c h a r a c t e r i z e d in that the eleventh connection (36) and the twelfth connection (38) are provided with force means (39) adapted to adjust the tensional stress of the tensile bar (14, 15) synchronically relative to each other and/or individually.

18. The press brake according to any one of claims 1 to 17, c h a r a c t e r i z e d in that a vertical post (52) is provided between the frame part (22) and the frame beam (9) on the center line (L - L) and mounted at the first end to the frame beam (9) and connected at the second end to the frame part (22) by a thirteenth connection (52) that forms a force node point and is disposed on said center line (L - L) ; that the thirteenth connection (52) is provided with an force means (39) adapted to generate a press force to the middle of the frame beam (9) through the vertical post.

19. The press brake according to any one of claims 11 to 18, c h a r a c t e r i z e d in that the force means (39) includes a cam mechanism (40).

20. The press brake according to claim 19, c h a r a c t e r i z e d in that the cam mechanism (40) includes a rotating shaft (41) , including

- a round shaft part (42) adapted to rotate in a first hole (43) on a first component,

- a round cam (44) which is eccentric relative to the shaft part (42) and adapted to rotate in a second hole (45) on a second component adjacent to the first component, and

- a hydraulic cylinder (46) is adapted to rotate the rotating shaft (41) .

21. The press brake according to claim 20, ch a r a c t e r i z e d in that the cam mechanism (40) includes a bent lever (47) mounted on the rotating shaft (41); and that the hydraulic cylinder (46) is adapted to turn the bent lever (47) in order to rotate the rotating shaft (41) .

22. The press brake according to any one of claims 11 to 18, c h a r a c t e r i z e d in that the force means (39) are hydraulic press cylinders (48) adapted directly or indirectly to act between a connection that forms a force node point and the frame beam (9) in or- der to generate a tensional force applied on the ten- sile bars (12, 13) and a press force applied on the frame beam.

23. The press brake according to claim 22, ch a r a c - t e r i z e d in that a set of vertically extending posts (49) is detachably mounted on the frame beam (9), the connections that form the force node points being formed at the ends of the posts; that a press cylinder (48) is fitted at the upper or the lower end of each post; and that the force distribution system of the lower beam and/or the upper beam includes horizontal tensile bars (50' , 50", 50"' ) , each being connected between each two connections on the same horizontal plane.

24. The press brake according to any one of claims 1 to 23, c h a r a c t e r i z e d in that the oblique tensile bar (12, 13) includes two slots (51) extending in the lengthwise direction thereof in parallel to each other.