EP0613740A1 - Process and hydraulic press for the pressing of sheets - Google Patents

Process and hydraulic press for the pressing of sheets Download PDF

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Publication number
EP0613740A1
EP0613740A1 EP94103041A EP94103041A EP0613740A1 EP 0613740 A1 EP0613740 A1 EP 0613740A1 EP 94103041 A EP94103041 A EP 94103041A EP 94103041 A EP94103041 A EP 94103041A EP 0613740 A1 EP0613740 A1 EP 0613740A1
Authority
EP
European Patent Office
Prior art keywords
sheet
blank holder
pressure
zero
frequency
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.)
Granted
Application number
EP94103041A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0613740B1 (en
Inventor
Mario Da Re'
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.)
Fiat Auto SpA
Original Assignee
Fiat Auto SpA
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 Fiat Auto SpA filed Critical Fiat Auto SpA
Publication of EP0613740A1 publication Critical patent/EP0613740A1/en
Application granted granted Critical
Publication of EP0613740B1 publication Critical patent/EP0613740B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • B21D24/00—Special deep-drawing arrangements in, or in connection with, presses
    • B21D24/10—Devices controlling or operating blank holders independently, or in conjunction with dies
    • B21D24/14—Devices controlling or operating blank holders independently, or in conjunction with dies pneumatically or hydraulically
    • 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
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/20—Deep-drawing
    • B21D22/26—Deep-drawing for making peculiarly, e.g. irregularly, shaped articles
    • 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
    • B21D24/00—Special deep-drawing arrangements in, or in connection with, presses
    • B21D24/04—Blank holders; Mounting means therefor
    • B21D24/08—Pneumatically or hydraulically loaded blank holders

Definitions

  • the invention concerns a process for the pressing of metal sheets, particularly the deep drawing (drawing) of motor vehicle body components.
  • the invention also concerns a hydraulic press capable of implementing the above-mentioned pressing process.
  • a sheet is installed between a matrix and a punch of the die, clamped with pre-determined force by a blank holder which has the task of restraining the sheet against the matrix in the course of the plastic deformation operation.
  • the value of the clamping pressure exerted by the blank holder against the sheet in the pressing phase is fixed and is determined by trials working initially on a batch of test sheets, to be then kept constant for the entire production phase.
  • the object of the invention is to provide an improved process of the pulsating pressure type disclosed above which enables the disadvantages of the latter to be overcome in a simple and economic manner thus enabling sheets, including aluminium sheets, to be processed in complex shapes at low cost.
  • the basis of the invention is therefore provided by a process for the pressing of metal sheets comprising the phases of : arranging a sheet between a matrix and a punch of a die which are shaped in the shape of a component to be obtained; and deforming the sheet by means of the said matrix and punch, restraining the sheet between these latter exerting on the sheet, by means of a blank holder, a pulsating pressure alternately variable between a minimum value and a maximum value; characterized in that a minimum restraining pressure equal to zero is exerted on the sheet; the said pulsating pressure having a predetermined frequency which is selected according to the mechanical properties of the sheet to be pressed.
  • the pulsating pressure variation frequency is between zero and 20 Hz inclusive and is selected at a value that is higher, the lower the hardness of the sheet used. In this way even aluminium sheets become easy to process.
  • the frequency of the said pulsating pressure is made to vary in the course of the pressing operation, particularly in the course of the active stroke of the punch and in any event so as to obtain at least one pressure variation cycle from zero to the maximum value for every 8-10 mm of depth of drawing of the sheet. In this way the rejects are reduced, substantially to zero, even where very complex pressings are involved.
  • the process according to the invention can be implemented on a hydraulic press for the pressing of sheets, of the type comprising at least one blank holder controlled by actuators via a hydraulic control circuit comprising valve means for alternately pressurizing/depressurizing the blank holder actuators, characterized in that the said valve means are capable of causing the pressure exerted on the sheet by the blank holder to vary between a pre-determined maximum value and a minimum value equal to zero; the said valve means comprising timing means for selectively varying the alternate pressurizing/depressurizing frequency of the said actuators on a continuous basis.
  • press 1 represents a hydraulic press for the pressing of metal sheets 2, made of steel or aluminium or light alloy, for example, particularly to obtain body components of a vehicle which are known and not shown for reasons of simplicity;
  • press 1 comprises a die 3 formed by least one matrix 4 and at least one punch 5 having a profile that is conjugate and shaped like the body component to be obtained, and a blank holder 6 capable of acting on the sheet 2 in correspondence with a perimetric portion 8 thereof.
  • the blank holder 6, rather than being made of a single piece, consists of a multiplicity of restraining elements 10, four in number for example, one for each side of the sheet 8, which can be controlled independently of each other.
  • press 1 comprises a hydraulic circuit 18 to control actuators 20 associated with the blank holder 6, particularly associated, singly or in pairs (or three or more according to need) with each restraining element 10.
  • the circuit 18 comprises in its turn a valve assembly 22 controlled by an electronic microprocessor unit 23 and capable of controlling the inflow and outflow of control fluid to each actuator 20 associated with each element 10, independently for each said element 10.
  • valve assembly 22 is of the same type as vehicle anti-lock brake systems (ABS) and so is not described for reasons of simplicity. Substantially, it is capable of selectively intercepting the flow supplied by a pump 24 towards each actuator 20 for very short periods of time and, possibly, of connecting the actuator to an outlet 25, so as to generate in the actuators 20 a control pressure variable with a periodic law or with a substantially stepwise profile between zero (corresponding to the point at which assembly 22 completely intercepts the said flow and then prevents it from reaching the actuator 20 and, if necessary, connects the actuator 20 to the outlet 25) and a pre-determined maximum value dependent on the characteristic of the pump 24 and, for example, adjustable via the assembly 22 by drawing under the control of the unit 23 (corresponding to the point at which the assembly 22 connects, directly or with drawing towards a pressure control valve which forms part of that assembly, the actuator 20 with the pump 24).
  • ABS vehicle anti-lock brake systems
  • the unit 23 is capable of controlling the assembly 22 (for example comprising a set of "on-off" type solenoid valves) so as to be able to vary on a continuous basis the periodicity, i.e. the frequency, of the periodic pressure variation law in the actuators 20, for example between a minimum frequency equal to zero (the pressure does not vary and remains constant) and a maximum frequency equal to approximately 20 Hz. Consequently, each element 10 is capable of applying to the sheet 2 a restraining pressure variable between zero (corresponding to the point at which the actuator/the actuators controlling this element 10 are at zero pressure) and a maximum pressure that is adjustable at will, with a frequency which can also be varied as desired between 0 and 20 Hz.
  • the assembly 22 for example comprising a set of "on-off" type solenoid valves
  • control circuit 18 is completed by a hydraulic accumulator 26 for supplying the assembly 22 at constant pressure, a filter 27 and a valve assembly 28 which controls an actuator 29 (not shown in Fig. 1) for raising the blank holder 6, and also exhaust valves 30 of actuators 20.
  • the pulsating pressure must have a frequency selected according to the mechanical properties of the sheet to be pressed, particularly between zero and 20 Hz inclusive (the installation must be capable of achieving the zero value also, but the minimum operating frequency must be not less than 3 Hz) and of a value that is higher, the lower the hardness/strength of the sheet 2 being processed.
  • a frequency selected according to the mechanical properties of the sheet to be pressed, particularly between zero and 20 Hz inclusive (the installation must be capable of achieving the zero value also, but the minimum operating frequency must be not less than 3 Hz) and of a value that is higher, the lower the hardness/strength of the sheet 2 being processed.
  • FePO4 for example (designation according to UNI 5866/77 and EURONORM 130/77) between 0.8 and 1 mm thick the frequency must be relatively low, between 8 and 10 Hz inclusive for example; in contrast, for aluminium sheets 0.7-1 mm thick it is necessary to use higher frequencies, between 14 and 18 Hz inclusive.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
  • Control Of Presses (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
EP94103041A 1993-03-02 1994-03-01 Process and hydraulic press for the pressing of sheets Expired - Lifetime EP0613740B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO930148 1993-03-02
ITTO930148A IT1260615B (it) 1993-03-02 1993-03-02 Procedimento e pressa idraulica per lo stampaggio di lamiere

Publications (2)

Publication Number Publication Date
EP0613740A1 true EP0613740A1 (en) 1994-09-07
EP0613740B1 EP0613740B1 (en) 1997-09-10

Family

ID=11411217

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94103041A Expired - Lifetime EP0613740B1 (en) 1993-03-02 1994-03-01 Process and hydraulic press for the pressing of sheets

Country Status (5)

Country Link
EP (1) EP0613740B1 (un)
JP (1) JPH0747432A (un)
DE (1) DE69405426T2 (un)
ES (1) ES2105375T3 (un)
IT (1) IT1260615B (un)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0740968A1 (en) * 1995-05-01 1996-11-06 Toyota Jidosha Kabushiki Kaisha Pressing method and system wherein cushion pin load is detected by load detector for diagnosis for even distribution of blank holding force
US6691545B1 (en) 1999-06-21 2004-02-17 Hydraulico A/S Tool and a method for pressure shaping
WO2020099060A1 (de) * 2018-11-13 2020-05-22 Moog Luxembourg S.à.r.l. Elektrohydrostatisches aktuatorsystem

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2297983B1 (es) * 2005-08-03 2009-07-17 Batz, S. Coop. Procedimiento para embutir chapas metalicas.
JP4958721B2 (ja) * 2007-10-17 2012-06-20 アイダエンジニアリング株式会社 サーボモータ駆動方式のプレス機械
JP4832476B2 (ja) * 2008-07-18 2011-12-07 サムテック株式会社 金属容器の製造方法および金属容器製造装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1481202A (en) * 1976-03-29 1977-07-27 Metal Box Co Ltd Deep drawing
US4745792A (en) * 1986-10-14 1988-05-24 Aluminum Company Of America Blankholder for a draw press
DE4038866A1 (de) * 1989-12-05 1991-07-18 Forschungszentrum Fuer Umform Verfahren zum tiefziehen von blechformteilen
EP0438774A1 (en) * 1990-01-24 1991-07-31 FIAT AUTO S.p.A. A method of pressing sheet metal and a hydraulic press for carrying out the method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1481202A (en) * 1976-03-29 1977-07-27 Metal Box Co Ltd Deep drawing
US4745792A (en) * 1986-10-14 1988-05-24 Aluminum Company Of America Blankholder for a draw press
DE4038866A1 (de) * 1989-12-05 1991-07-18 Forschungszentrum Fuer Umform Verfahren zum tiefziehen von blechformteilen
EP0438774A1 (en) * 1990-01-24 1991-07-31 FIAT AUTO S.p.A. A method of pressing sheet metal and a hydraulic press for carrying out the method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0740968A1 (en) * 1995-05-01 1996-11-06 Toyota Jidosha Kabushiki Kaisha Pressing method and system wherein cushion pin load is detected by load detector for diagnosis for even distribution of blank holding force
US6691545B1 (en) 1999-06-21 2004-02-17 Hydraulico A/S Tool and a method for pressure shaping
WO2020099060A1 (de) * 2018-11-13 2020-05-22 Moog Luxembourg S.à.r.l. Elektrohydrostatisches aktuatorsystem
US11384778B2 (en) 2018-11-13 2022-07-12 Moog Luxembourg S.a.r.l. Electro-hydrostatic actuator system

Also Published As

Publication number Publication date
EP0613740B1 (en) 1997-09-10
ITTO930148A1 (it) 1994-09-02
ES2105375T3 (es) 1997-10-16
DE69405426T2 (de) 1998-02-12
ITTO930148A0 (it) 1993-03-02
IT1260615B (it) 1996-04-22
DE69405426D1 (de) 1997-10-16
JPH0747432A (ja) 1995-02-21

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