EP1769857A2 - Biegepresse mit einem Werkzeughalter und mit reduzierter Verformung - Google Patents

Biegepresse mit einem Werkzeughalter und mit reduzierter Verformung Download PDF

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Publication number
EP1769857A2
EP1769857A2 EP20060115762 EP06115762A EP1769857A2 EP 1769857 A2 EP1769857 A2 EP 1769857A2 EP 20060115762 EP20060115762 EP 20060115762 EP 06115762 A EP06115762 A EP 06115762A EP 1769857 A2 EP1769857 A2 EP 1769857A2
Authority
EP
European Patent Office
Prior art keywords
tool holder
holder table
relative
bending press
movable
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP20060115762
Other languages
English (en)
French (fr)
Inventor
Giovanni Vidotto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Crea SRL
Original Assignee
Crea SRL
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Crea SRL filed Critical Crea SRL
Publication of EP1769857A2 publication Critical patent/EP1769857A2/de
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
    • B21D5/02—Bending sheet metal along straight lines, e.g. to form simple curves on press brakes without making use of clamping means
    • B21D5/0272—Deflection compensating means

Definitions

  • the present invention relates to bending presses for bending pieces of sheet metal.
  • Figure 1 shows the structure of a bending press of the type most widely found on the market.
  • the bending press 10 comprises an upper tool holder table 12, a lower tool holder table 14 and a support structure including two lateral uprights 16 and stiffening cross members 18.
  • the tool holder tables 12, 14 have respective end portions 20, 22 whereto are fastened the bending tools (dies and punches).
  • the movement and the force necessary to the bending process are obtained by means of hydraulic or electromechanical actuators 24 that move the upper tool holder table 12 relative to the lower tool holder table 14.
  • the rectilinear nature of the bending line is a necessary condition to assure an accurate bending quality.
  • the resulting bending line tends to follow the deformed line of the tool holder tables.
  • a diversity of the profile of the deformed line of the upper table relative to the lower table causes a variation in the bending angle along the bending line, because the deformed line diversity causes the two tools (punch and die) to interpenetrate by a different quantity along the bending line, in addition to a non rectilinear nature of the bending line.
  • Figure 2 shows the typical defects of a piece of bent sheet metal P caused by the deformation of the tool holder tables.
  • the bending line L is not rectilinear and the bending angle ⁇ varies along the bending line.
  • Figure 3 is a front view showing a typical bending press structure.
  • the upper tool holder table 12 has two lateral extensions 26 whereon act the actuators 24 (in this case, hydraulic) by means of cylindrical bearing elements 28.
  • the bearing elements 28 serve as a hinge and allow mutual rotations of the lateral extensions 26 relative to the rods of the actuators 24 which derive from the elastic deformation of the upper table 12.
  • the actuators 24 are positioned laterally relative to the upper table 12, the latter is generally very high, in order to increase the moment of inertia (and hence the rigidity) and to reduce deformations.
  • Figure 4a shows the upper tool holder table 12 subjected to a bending load uniformly distributed along a bending line with a length equal to the length of the table.
  • Figure 4b shows that the upper tool holder table 12 is equivalent to a beam bearing on the ends and subjected to a uniformly distributed load.
  • Figure 4c shows the deformation of the beam equivalent to the table 12 under the action of the bending load.
  • Figure 6 shows the comparison between the deformed lines of the tool holders 12, 14. The difference between the two deformed lines causes on the piece a variation of the bending angle along the bending line, as shown schematically in Figure 2.
  • Figures 7a and 7b show a known solution used on AMADA bending presses.
  • the lower tool holder table 14 is arranged in sandwich fashion between two support tables 30, fixed relative to the support structure of the press.
  • the tool holder table 14 is connected to the support tables 30 by means of two pivot pins 32, orthogonal with respect to the tables 14, 30.
  • Figure 8 shows the deformation of the upper table and of the lower table in a bending press of the type shown in Figure 7.
  • the object of the present invention is to reduce the deformations of the upper tool holder table without, however, increasing its moment of inertia.
  • the present invention changing the constraining conditions of the upper tool holder table, aims to obtain smaller deformations for equal inertia moments, or, for equal deformation of the upper tool holder table, a reduction in its moment of inertia.
  • said object is achieved by a bending press having the characteristics set out in the claims.
  • Figure 9 schematically shows the upper table of a bending press according to the present invention.
  • the elements corresponding to the previously described ones are hereafter designated by the same numeric references.
  • the actuators 24 do not act directly on the tool holder table 12.
  • the ends 28 of the actuators 24 act on one or more load application beams 34 positioned forward and/or rearward relative to the tool holder table 12.
  • two load application beams 34 are positioned at opposite sides relative to the tool holder table 12.
  • the load application beams 34 are connected to the tool holder table 12 by means of two pivot pins 36 which extend orthogonally relative to the tool holder table 12 and to the load application beams 34.
  • the tool holder table 12 is connected to the support structure of the brake by means of guides (not shown) that constrain the tool holder table 12 to move along a vertical plane.
  • Two position transducers 38 sense the position of the upper tool holder table 12 relative to the lower tool holder table, similarly to what occurs in bending presses available commercially.
  • the bending load is applied to the tool holder table 12 in areas situated between the actuators 24.
  • the upper tool holder table 12 behaves like a beam with constraints placed in intermediate position and hence, for equal moment of inertia of the section and equal load, it has smaller elastic deformations than those of an equivalent beam supported at the ends.
  • Figure 10a shows the load distributed along the upper tool holder table 12 according to the present invention.
  • Figure 10b shows the beam equivalent to the tool holder table 12 and
  • Figure 10c shows the deformation under load of the tool holder table 12.
  • FIG. 11 shows a comparison between the deformed lines of a beam equivalent to a tool holder table according to the present invention (line a) and of a beam equivalent to a tool holder table according to the prior art (line b). From Figure 11 it is readily apparent that, for equal dimensions of the tool holder table, in the solution according to the present invention the deformations are sharply smaller. In this way, it is possible to reduce the curving effect on the bending lines due to the deformation of the tool holder tables, because the line of the tools during the bending operation is closer to the ideal condition of a straight line. Accepting instead to have the same allowable maximum deformation as a bending press according to the prior art, with the present invention it is possible to reduce the height of the tool holder table, saving material and reducing the height of the brake.
  • the elastic deformation of the load application beams 34 has no effect on the deformation of the tool holder table 12 except by effect of the friction couples exchanged with the pivot pins due to the deformation of the beams 34, which in any case have a minimal effect on the deformation of the tool holder table 12.
  • the load application beams 34 can be dimensioned according to strength and/or admitting a greater deformation than that of the tool holder table 12, with consequent material savings.
  • the deformation of the load application beams 34 has no influence on the movement or on the deformation of the upper tool holder table 12, thanks to the management of the numeric control of the brake and thanks to the control of the position of the tool holder table 12 by means of the position transducers 38.
  • Figure 12 shows a possible embodiment which comprises a system compensating the lower table 14.
  • the lower tool holder table 14 is fastened to the lateral uprights 16 of the support structure by means of hinges 40 which allow the rotation of the lower table 14 relative to the uprights 16 deriving from the elastic deformation of the table under load.
  • One or more supporting cross members 42 are fastened to the uprights 16 of the support structure, also by means of hinges.
  • the support cross members 42 are positioned to the front and/or to the rear of the lower tool holder table 14.
  • the latter has, in a central position, a seat 44 in which is housed a hydraulic or electromechanical balancing actuator 46.
  • the rod of the actuator 46 is fastened by means of an articulation to the upper surface of the housing 44 obtained in the lower table 14 whilst the body of the actuator 46 is fastened to the supporting cross members 42.
  • a position transducer 48 is integral to a measuring cross member fastened to the uprights 16 of the support structure in isostatic fashion.
  • the position transducer 48 senses the deformation of the lower table 14 relative to the measuring cross member 50.
  • the bending press 10 is commanded by a numeric control unit 52.
  • the control unit 52 receives the signals coming from the position transducers 38 and 48. Based on the signals provided by the transducers 38, the numeric control 52 commands the actuators 24 that actuate the upper tool holder table 12. Based on the signal provided by the position transducer 48, the numeric control 52 commands the force exerted by the balancing actuator 46.
  • the pressure that acts on the balancing cylinder 46 it is possible to control the deformation of the lower table, in order to maintain said deformation within predetermined limits.
  • the lower table 14 behaves like a beam bearing on three points, i.e. two end bearings and an intermediate bearing.
  • Figure 13 shows the profile of the deformation of the tool holder tables 12 and 14 and Figure 14 shows the comparison between the two deformed lines.
  • the profile of the two deformed lines is similar, so a constant bending angle is obtained along the bending line.
  • Figure 16 shows a possible variant of the present invention, in which the position of the constraints between the load application beams 34 and the upper tool holder table 12 was made variable. To do so, the pivot pins that transmit the forces from the beam 34 to the tool holder table were replaced by bearings 52 slidable along guides 58 along the longitudinal axis of the upper tool holder table 12.
  • the load application beams 34 were modified introducing an upper connecting cross member 60 between the two beams 34.
  • the force produced by the actuators 24 is transmitted to the upper tool holder table 12 by contact between the upper cross member 60, the slidable bearings 26 and the upper plane of the tool holder table 12.
  • a securing system prevents the tool holder table 12 from detaching from the bearings 56 under its own weight.
  • the brake of Figure 10 is provided with a similar system to the one described above for measuring the position of the upper tool holder table 12.
  • the balancing actuator 46 of the lower tool holder table 14 is movable along the longitudinal axis of the lower table 14.
  • the balancing actuator 46 was doubled in such a way as to balance the torque due to the fact that these actuators do not work aligned with the median plane of the lower table 14, as in the case described above.
  • the positioning of the bearings 56 and of the balancing cylinders 46 can occur manually or by means of the numeric control.
  • the advantage that derives from the ability to vary the constraint condition of the upper tool holder table 12 and of the balancing actuator 46 is that it is possible to optimise the elastic deformation of the upper and lower tool holder tables 12, 14 according to the distribution of the tools (and hence of the bending stresses acting between the tables 12, 14). It is therefore possible to find a position of the constraints that minimises the elastic deformation of the tables.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Bending Of Plates, Rods, And Pipes (AREA)
EP20060115762 2005-09-29 2006-06-21 Biegepresse mit einem Werkzeughalter und mit reduzierter Verformung Withdrawn EP1769857A2 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ITTO20050676 ITTO20050676A1 (it) 2005-09-29 2005-09-29 Pressa piegatrice con tavola portautensili a deformazione ridotta

Publications (1)

Publication Number Publication Date
EP1769857A2 true EP1769857A2 (de) 2007-04-04

Family

ID=37560901

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20060115762 Withdrawn EP1769857A2 (de) 2005-09-29 2006-06-21 Biegepresse mit einem Werkzeughalter und mit reduzierter Verformung

Country Status (2)

Country Link
EP (1) EP1769857A2 (de)
IT (1) ITTO20050676A1 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102228917A (zh) * 2011-05-19 2011-11-02 中国一冶集团有限公司 顶压式卷板装置
WO2013072859A1 (pt) * 2011-11-15 2013-05-23 Adira, S.A. Avental para compensação de deformação para quinadoras
CN103785721A (zh) * 2014-01-03 2014-05-14 南京邮电大学 一种数控金属板材折弯机
CN105855379A (zh) * 2016-05-31 2016-08-17 安徽力源数控刃模具制造有限公司 一种折弯机工作台挠度补偿装置及补偿方法

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102228917A (zh) * 2011-05-19 2011-11-02 中国一冶集团有限公司 顶压式卷板装置
WO2013072859A1 (pt) * 2011-11-15 2013-05-23 Adira, S.A. Avental para compensação de deformação para quinadoras
CN103785721A (zh) * 2014-01-03 2014-05-14 南京邮电大学 一种数控金属板材折弯机
CN105855379A (zh) * 2016-05-31 2016-08-17 安徽力源数控刃模具制造有限公司 一种折弯机工作台挠度补偿装置及补偿方法

Also Published As

Publication number Publication date
ITTO20050676A1 (it) 2007-03-30

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