US20150266077A1 - Stretch forming system and stretch forming method - Google Patents

Stretch forming system and stretch forming method Download PDF

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Publication number
US20150266077A1
US20150266077A1 US14/434,141 US201314434141A US2015266077A1 US 20150266077 A1 US20150266077 A1 US 20150266077A1 US 201314434141 A US201314434141 A US 201314434141A US 2015266077 A1 US2015266077 A1 US 2015266077A1
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United States
Prior art keywords
die
jaws
workpiece
orientations
respect
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Abandoned
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US14/434,141
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English (en)
Inventor
Tsuyoshi Kimura
Seishiro Kawano
Shinichi Nakano
Fumihiro Honda
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Kawasaki Motors Ltd
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Kawasaki Jukogyo KK
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Assigned to KAWASAKI JUKOGYO KABUSHIKI KAISHA reassignment KAWASAKI JUKOGYO KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HONDA, FUMIHIRO, NAKANO, SHINICHI, KAWANO, Seishiro, KIMURA, TSUYOSHI
Publication of US20150266077A1 publication Critical patent/US20150266077A1/en
Abandoned legal-status Critical Current

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    • 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
    • B21D25/00—Working sheet metal of limited length by stretching, e.g. for straightening
    • B21D25/02—Working sheet metal of limited length by stretching, e.g. for straightening by pulling over a die
    • 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
    • B21D11/00—Bending not restricted to forms of material mentioned in only one of groups B21D5/00, B21D7/00, B21D9/00; Bending not provided for in groups B21D5/00 - B21D9/00; Twisting
    • B21D11/02—Bending by stretching or pulling over a die
    • 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
    • B21D25/00—Working sheet metal of limited length by stretching, e.g. for straightening
    • B21D25/04—Clamping arrangements

Definitions

  • the present invention relates to a stretch forming system and a stretch method for performing stretch forming of a workpiece.
  • a stretch forming is conventionally performed for stretch forming of a workpiece into a desired shape.
  • the stretch forming is performed by using a stretch forming apparatus including first and second jaws clamping a plate-shaped workpiece at respective end edge portions opposite to each other, a die disposed between the first and second jaws and coming into contact with the workpiece, and multiple axes changing the relative positions and orientations of the jaws with respect to the die.
  • a stretch forming apparatus including first and second jaws clamping a plate-shaped workpiece at respective end edge portions opposite to each other, a die disposed between the first and second jaws and coming into contact with the workpiece, and multiple axes changing the relative positions and orientations of the jaws with respect to the die.
  • the stretch forming must be performed such that a workpiece is prevented from wrinkling, that the thickness of the workpiece is substantially uniformly changed across the entire part, and that no gap is generated between the workpiece and the die. Therefore, the operator must devise paths of the relative positions and orientations of the jaws with respect to the die necessary for achieve this stretch forming as well as respective operation patterns of the multiple control axes necessary for achieving the paths of the positions and orientations of the jaws. This is time-consuming and therefore a burden for the operator, and is difficult unless the worker is skilled.
  • the present invention is configured as follows.
  • a stretch forming system comprising:
  • first and second jaws clamping a workpiece at respective end edge portions opposite to each other;
  • control axes changing relative positions and orientations of the first and second jaws with respect to the die
  • a jaw path calculating unit calculating respective paths of the relative positions and orientations of the first and second jaws with respect to the die when the workpiece is wrapped onto the die by moving the die in a vertical direction under a restricting condition that respective positions and orientations of the first and second jaws are freely changeable except for movement in a vertical direction being regulated;
  • a control axis operation pattern calculating unit calculating respective operation patterns of the plurality of the control axes achieving the respective paths of the relative positions and orientations of the first and second jaws with respect to the die calculated by the jaw path calculating unit.
  • a stretch forming system comprising:
  • first and second jaws clamping a workpiece at respective end edge portions opposite to each other;
  • control axes changing relative positions and orientations of the first and second jaws with respect to the die
  • a jaw path calculating unit calculating respective paths of the relative positions and orientations of the first and second jaws with respect to the die when the workpiece is wrapped onto the die by moving the die in a vertical direction under a restricting condition that respective positions and orientations of the first and second jaws are freely changeable except for movement in a vertical direction being regulated and rotation around a rotation center line being regulated, the rotation center line extending in a direction that is a horizontal direction orthogonal to a jaw facing direction;
  • a control axis operation pattern calculating unit calculating respective operation patterns of the plurality of the control axes achieving the respective paths of the relative positions and orientations of the first and second jaws with respect to the die calculated by the jaw path calculating unit.
  • the stretch forming system according to the first or second aspect, wherein the jaw path calculating unit calculates the respective paths of the relative positions and orientations of the first and second jaws with respect to the die by using a workpiece having a thickness thinner than the thickness of the actual workpiece.
  • the stretch forming system according to any one of the first to third aspect, further comprising a die movement amount calculating unit calculating first and second intersections between the respective paths of the relative positions of the first and second jaws with respect to the die calculated by the jaw path calculating unit and respective tangent lines at the both end edge portions of a forming surface of the die,
  • the die movement amount calculating unit calculating first and second vertical direction distances from the calculated first and second respective intersections to an apex of the die
  • the die movement amount calculating unit comparing the calculated first and second vertical direction distances with each other to determine the greater one as a relative vertical-direction movement amount of the die with respect to the first and second jaws.
  • a stretch forming method of using first and second jaws clamping a workpiece at respective end edge portions opposite to each other, a die disposed between the first and second jaws and coming into contact with the workpiece, and a plurality of control axes changing relative positions and orientations of the first and second jaws with respect to the die to wrap the workpiece onto the die by the first and second jaws for forming, the method including
  • a stretch forming method of using first and second jaws clamping a workpiece at respective end edge portions opposite to each other, a die disposed between the first and second jaws and coming into contact with the workpiece, and a plurality of control axes changing relative positions and orientations of the first and second jaws with respect to the die to wrap the workpiece onto the die by the first and second jaws for forming, the method including
  • the present invention enables the calculation of the paths of the relative positions and orientations of the jaws with respect to the die, i.e., the respective operation patterns of the multiple control axes, necessary for acquiring a favorable formed product from the stretch forming on behalf of an operator in a short period of time. As a result, the burden of the operator can be reduced.
  • FIG. 1 is a model diagram of a configuration of control axes of a stretch forming apparatus included in a stretch forming system according to an embodiment of the present invention.
  • FIG. 2 is a schematic perspective view of jaws and a die of the stretch forming apparatus depicted in FIG. 1 .
  • FIGS. 3A-3D are diagrams for explaining a flow of exemplary stretch forming.
  • FIG. 4 is a schematic configuration diagram of a control program creating apparatus creating a control program for automatically controlling the operations of the control axes.
  • FIGS. 5A and 5B are diagrams for explaining the paths of the jaws calculated by a jaw path calculating unit.
  • FIG. 6 is a diagram for explaining a die rise amount calculated by a die movement amount calculating unit.
  • FIGS. 7A and 7B are diagrams for explaining another stretch forming.
  • FIG. 8 is a diagram for explaining yet another stretch forming.
  • FIG. 9 is a diagram for explaining further stretch forming.
  • FIG. 1 is a schematic of a configuration of a stretch forming apparatus included in a stretch forming system according to an embodiment of the present invention.
  • a stretch forming apparatus 10 has two jaws J L , J R opposite to each other and a die D.
  • FIG. 2 which is a schematic perspective view of the jaws J L , J R and the die D, the jaws J L , J R are configured to clamp a plate-shaped workpiece W in the thickness direction at respective end edge portions opposite to each other.
  • the die D is disposed between the jaws J L , J R and is configured to come into contact with the workpiece W from below.
  • the die D includes a curved forming surface Ds coming into contact with the workpiece W.
  • the stretch forming apparatus 10 has a system coordinate system ZS defined by an X axis, a Y axis, and a Z axis orthogonal to each other.
  • An X direction and a Y direction are horizontal directions and a Z direction is a vertical direction.
  • the die D is has a die coordinate system ⁇ D defined by an X D axis, a Y D axis, and a Z D axis orthogonal to each other as shown in FIGS. 1 and 2 .
  • the respective jaws J L , J R have jaw coordinate systems ⁇ J L , ⁇ J R defined as orthogonal coordinate systems as shown in FIGS. 1 and 2 .
  • the origins of the jaw coordinate systems ⁇ J L , ⁇ J R are located at reference points R JL , R JR of the jaws J L , J R positioned at the grip centers of the workpiece W of the jaws J L , J R .
  • the reference points R JL , R JR are located at the centers of the portions of the workpiece W clamped by the jaws J L , J R and the surfaces of the portions of the workpiece W clamped by the jaws J L , J R are orthogonal to a Z JL axis and a Z JR axis.
  • the stretch forming apparatus 10 also has control axes for the die for changing the position and orientation of the die D, which are a die elevating/lowering axis J D1 for elevating and lowering the die D in the vertical direction (Z direction) relative to a base B of the stretch forming apparatus 10 and a die tilt axis J D2 for rotating the die D around a rotation center line C D1 extending in parallel with the X axis.
  • control axes for the die for changing the position and orientation of the die D which are a die elevating/lowering axis J D1 for elevating and lowering the die D in the vertical direction (Z direction) relative to a base B of the stretch forming apparatus 10 and a die tilt axis J D2 for rotating the die D around a rotation center line C D1 extending in parallel with the X axis.
  • the stretch forming apparatus 10 also has control axes for the jaw J L changing the position and orientation of the jaw J L , which are, in the order from the base B of the stretch forming apparatus 10 to the jaw J L , a carriage axis J L1 for stroking the jaw J L in parallel with the X axis, an angulation axis J L2 for rotating the jaw J L around a rotation center line C L1 extending in parallel with the Z axis, a slider axis J L3 for stroking the jaw J L in the horizontal direction (parallel with an X-Y plane), a swing axis J L4 for rotating the jaw J L around a rotation center line C L2 extending in parallel with the stroke direction of the slider axis J L3 , a tension axis J L5 for stroking the jaw J L in the linear direction orthogonal to the rotation center line C L2 of the swing axis J L4 , and a rotation axis J L6 for rotating the jaw J L around a
  • the stretch forming apparatus 10 also has control axes for the jaw J R for changing the position and orientation of the jaw J R , which are, in the order from the base B of the stretch forming apparatus 10 to the jaw J R , a carriage axis J R1 for stroking the jaw J R in parallel with the X axis, an angulation axis J R2 for rotating the jaw J R around a rotation center line C R1 extending in parallel with the Z axis, a slider axis J R3 for stroking the jaw J R in the horizontal direction (parallel with the X-Y plane), a swing axis J R4 for rotating the jaw J R around a rotation center line C R2 extending in parallel with the stroke direction of the slider axis J R3 , a tension axis J R5 for stroking the jaw J R in the linear direction orthogonal to the rotation center line C R2 of the swing axis J R4 , and a rotation axis J R6 for rotating the jaw J R
  • the jaws J L , J R can have six degrees of freedom in the die coordinate system ED.
  • the jaws J L , J R can move in parallel in the X D , Y D , and Z D directions of the die coordinate system ED and can rotate around the X D , Y D , and Z D axes.
  • the stretch forming apparatus 10 has a control unit (not shown) controlling the 14 control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 .
  • the stretch forming apparatus 10 has driving cylinders (not shown) driving the control axes for the respective control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 and the control unit controls the driving cylinders.
  • the driving cylinders driving the control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 are fluid pressure cylinders (e.g., hydraulic cylinders) and an oil pressure is supplied to each of a rod-side cylinder chamber and a head-side cylinder chamber adjacent across a piston.
  • the control unit controls hydraulic system constituent elements such as an electromagnetic valve and a hydraulic pump (not depicted) to adjust the respective oil pressures supplied to the rod-side cylinder chamber and the head-side cylinder chamber, thereby controlling the respective driving cylinders of the control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 .
  • the control unit of the stretch forming apparatus 10 is configured to provide to the driving cylinders the position control for controlling a piston position or the pressure control for controlling a cylinder output.
  • the stretch forming apparatus 10 is configured such that an operator can select whether the position control or the pressure control of the driving cylinder is provided, for each of the control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 .
  • the rotation axes such as the die tilt axis J D2 , the angulation axes J L2 , J R2 , the swing axes J L4 , J R4 , and the rotation axes J L6 , J R6 are used for rotating the die D and the jaws J L , J R within a predetermined angular range via crank mechanisms by advance and retreat of rods of the driving cylinders.
  • the control unit provides the position control of the driving cylinders, the angular positions of the die and the jaws are controlled around the rotation center lines of the rotation axes.
  • the control unit provides the pressure control of the driving cylinders, the torque of the rotation axes is controlled.
  • the translation axes such as the die elevating/lowering axis J D1 , the carriage axes J L1 , J R1 , the slider axes J L3 , J R3 , and the tension axes J L5 , J R5 are used for stroking the die D and the jaws J L , J R within a predetermined range by advance and retreat of the driving cylinders.
  • the control unit provides the position control of the driving cylinders, the positions of the die and the jaws are controlled within the stroke ranges of the translation axes.
  • the control unit provides the pressure control of the driving cylinders, the thrust force of the translation axes is controlled.
  • the jaws J L , J R hold the workpiece W in a horizontally extending orientation.
  • the jaws J L , J R are in a horizontal orientation such that the stroke directions of the tension axes C L5 , C R5 of the jaws J L , J R (i.e., the X JL and X JR directions) match the horizontal direction.
  • the load control of the tension axes C L5 , C R5 of the jaws J L , J R may be provided to stretch the workpiece W by a predetermined amount, for example, about 1% of a workpiece length (the length of the workpiece W in the X direction shown in FIG. 2 ) (hereinafter, such a stretch is referred to as “pre-stretch”).
  • the die D then rises and the forming surface Ds comes into contact with the workpiece W.
  • the positions and orientations of the respective jaws J L , J R are changed to wrap the workpiece W onto the forming surface Ds of the die D.
  • the orientations of the jaws J L , J R are changed such that the stroke directions of the tension axes J L5 , J R5 (i.e., the X JL and X JR directions) match the extending directions of the workpiece W (i.e., the directions of the workpiece W extending from the die D toward the jaws J L , J R ).
  • respective angle sensors are disposed on the jaws J L , J R to detect angles between the main bodies of the jaws J L , J R and portions of the workpiece W extending from the jaws J L , J R .
  • the orientations of the jaws J L , J R are changed such that the angle sensors continuously detect the angles at which the stroke directions of the tension axes J L5 , J R5 match the extending directions of the workpiece W.
  • the workpiece W may be wrapped onto the die D while the workpiece W is stretched by the jaws J L , J R .
  • the load control of the tension axes J L5 , J R5 of the jaws J L , J R (the pressure control of the cylinders thereof) is provided to stretch the workpiece W by about 1% of the workpiece length from the start to the end of wrapping (hereinafter, such a stretch is referred to as “wrapping-time stretch”).
  • the stretch forming system of this embodiment including the stretch forming apparatus 10 is configured such that the exemplary stretch forming shown in FIGS. 3A-3D can be performed by an operator manually operating the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 or by automatically controlling the operations of the multiple control axes J D1 to J D2 . J L1 to J L6 , J R1 to J R6 .
  • the stretch forming system of this embodiment is configured such that a control program can be created for automatically controlling the operations of the multiple control axes J D1 to J D2 .
  • J L1 to J L6 J R1 to J R6 .
  • J L1 to J L6 , J R1 to J R6 will hereinafter be described.
  • paths of the jaws J L , J R paths of the jaws J L , J R
  • the operator must also devise the respective operation patterns of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 achieving the paths of the jaws J L , J R .
  • this is time-consuming and therefore a burden for the operator, and is difficult unless the operator is skilled.
  • the stretch forming system of this embodiment is configured to calculate the paths of the jaws J L , J R necessary for acquiring a favorable formed product.
  • the stretch forming system is also configured to calculate the respective operation patterns of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 necessary for achieving the calculated paths of the jaws J L , J R .
  • the stretch forming system is configured to create a control program for operating the respective control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 in the calculated operation patterns.
  • FIG. 4 schematically shows configuration of a control program creating apparatus included in the stretch forming system of this embodiment.
  • the control program creating apparatus is made up of a personal computer in which software for creating the control program is installed, for example.
  • a method of creating the control program will hereinafter be described while describing the configuration of the control program creating apparatus.
  • a control program creating apparatus 50 has a forming condition acquiring unit 52 , a jaw path calculating unit 54 , a die movement amount calculating unit 56 , a control axis operation pattern calculating unit 58 , an FEM analyzing unit 60 , and a control program creating unit 62 .
  • the forming condition acquiring unit 52 is configured to acquire from the operator the forming conditions required for performing the stretch forming by wrapping the workpiece W onto the die D.
  • the control program creating apparatus 50 is made up of a personal computer, the forming conditions are acquired from the operator via input devices such as a mouse and a keyboard and graphic user interfaces such as a display.
  • the forming conditions acquired by the forming condition acquiring unit 52 from the operator include, for example, a shape of the die D, a shape of the workpiece W, a material (mechanical property) of the workpiece W, an initial position and an initial orientation of the workpiece W, initial positions and initial orientations of the respective jaws J L and J R , a pre-stretch amount (a stretch amount due to the pre-stretch), a wrapping-time stretch amount (a stretch amount due to a stretch at the time of wrapping), and a post-stretch amount (a stretch amount due to the post-stretch).
  • the initial positions and the initial orientations in this case refer to the start positions and the start orientations at the start of wrapping of the workpiece W onto the die D.
  • the jaw path calculating unit 54 is configured to perform simulation using a model of the stretch forming apparatus 10 based on the forming conditions acquired by the forming condition acquiring unit 52 from the operator so as to calculated the paths of the jaws J L , J R necessary for acquiring a favorable formed product, i.e., necessary for favorably wrapping the workpiece W onto the forming surface Ds of the die D.
  • the jaw path calculating unit 54 will be described. First, as shown in FIGS. 3A-3B , the respective positions and orientations of the jaws J L , J R are changed during the stretch forming while raising the die D. This is performed such that the workpiece W is prevented from wrinkling, that the thickness of the workpiece W is substantially uniformly changed across the entire part, and that no gap is generated between the workpiece W and the die D.
  • the following method is conceivable as a method of calculating the paths of the jaws J L , J R achieving this stretch forming.
  • the deformation behavior of the corresponding workpiece W is calculated by FEM (finite element method) analysis each time the parameters are changed. This is performed until the parameter values of the favorable deformation behavior of the workpiece W are found out.
  • the inventors thought that if the die D is in contact with the workpiece W held by the jaws J L , J R as shown in FIG. 5A and is moved in the contact direction (the Z direction), the workpiece W is favorably wrapped onto the forming surface Ds of the die D as shown in FIG. 5B , given that the movement of the jaws J L , J R is regulated only in the movement direction of the die D (the Z direction).
  • the inventors thought that the workpiece W is naturally wrapped onto the forming surface Ds of the die D without wrinkling, with the thickness of the workpiece W uniformly changed across the entire part, and without a gap generated between the workpiece W and the die D.
  • the inventors thought that if the jaws J L , J R are in a free state except the movement in the Z direction, since the positions and orientations of the jaws J L , J R are freely changed while the workpiece W is being wrapped onto the forming surface Ds due to the movement of the die D in the Z direction, the workpiece W is not significantly locally stretched (almost no local distortion is generated). Therefore, the inventors thought that the workpiece W is favorably wrapped onto the forming surface Ds of the die D such that a wrinkle is hardly generated, that the thickness of the workpiece W is substantially uniformly changed across the entire part, and that almost no gap is generated between the workpiece W and the die D.
  • the inventors thought that the paths P JL , P JR of the jaws J L , J R necessary for acquiring a favorable formed product can be calculated based on this idea in a shorter time as compared to the trial-and-error method.
  • the jaw path calculating unit 54 is configured to perform the simulation (wrapping simulation) in which, under the restricting condition that the positions and orientations of the jaws J L , J R can freely be changed except for the movement in the vertical direction (Z direction) being regulated, the workpiece W is wrapped onto the forming surface Ds of the die D by moving the die D in the vertical direction while the die D is in contact with the workpiece W held by the jaws J L , J R .
  • the jaw path calculating unit 54 is configured to calculate the paths P JL , P JR of the jaws J L , J R based on a result of the wrapping simulation.
  • the jaw path calculating unit 54 performs the wrapping simulation based on the forming conditions acquired by the forming condition acquiring unit 52 under the restricting condition regulating only the movement of the reference points R JL , R JR of the jaws J L , J R in the Z direction. For example, if the pre-stretch amount given as the forming condition is 2%, the wrapping simulation is performed by using a model of the workpiece W stretched by 2%.
  • the jaw path calculating unit 54 is configured to perform the wrapping simulation by using the workpiece W (model) having a thickness thinner than the thickness of the actual workpiece W. This is because when the thickness of the workpiece W is thinner, since the resistance during bending is less generated (the bending rigidity of the workpiece W is smaller), the workpiece W is more easily deformed with smaller distortion and, therefore, the workpiece W more easily comes into contact with the forming surface Ds of the die D (a gap is less generated) across the entire part. In other words, when the thickness of the workpiece W is thinner, the ideal paths P JL , P JR of the jaws J L , J R can be calculated such that the workpiece W comes into close contact with the forming surface Ds of the die D across the entire thereof.
  • the jaw path calculating unit 54 is configured to perform the wrapping simulation in which the die D is moved in the Z direction by a maximum movable amount to wrap the workpiece W onto the forming surface Ds of the die D. This is because the workpiece W is certainly wrapped onto the forming surface Ds of the die D across the entire thereof.
  • the jaw path calculating unit 54 may be configured to perform the wrapping simulation under the restricting condition that the friction coefficient is maximized between the workpiece W and the forming surface Ds of the die D. As a result, the workpiece W is restrained from slipping on the forming surface Ds of the die D in the wrapping simulation. Therefore, the wrapping simulation can be executed under the condition close to the actual apparatus. As a result, the paths P JL , P JR of the jaws J L , J R necessary for acquiring a favorable formed product can more accurately be calculated.
  • the jaw path calculating unit 54 is configured to output a result of the wrapping simulation to an operator. This allows the operator to determine whether the result of the wrapping simulation is favorable.
  • a display presents the positions and orientations of the jaws J L , J R , the position and orientation of the die D, the position, orientation, and shape of the workpiece W after the wrapping simulation as a result of the wrapping simulation.
  • This enables the operator to confirm whether the favorable paths P JL , P JR of the jaws J L , J R are calculated by the control program creating apparatus 50 based on the result of the wrapping simulation. If the wrapping simulation result is not favorable because of, for example, an abnormality of the shape of the workpiece W or an absence of contact between the workpiece W and the end edge portions of the forming surface Ds of the die D, the operator can properly change the forming conditions such as the initial positions and the initial orientations of the jaws J L , J R and the die D.
  • the paths P JL , P JR of the jaws J L , J R calculated by the jaw path calculating unit 54 are fixed.
  • the die movement amount calculating unit 56 of the control program creating apparatus 50 is configured to calculate the Z-direction movement amount of the die D based on the paths P JL , P JR of the jaws J L , J R calculated by the jaw path calculating unit 54 (determined as being favorable by the operator).
  • the paths P JL , P JR of the jaws J L , J R calculated by the jaw path calculating unit 54 are the paths when the die D is moved in the Z direction by the maximum movable amount. This is because the paths P JL , P JR of the jaws J L , J R are obtained such that the workpiece W is certainly wrapped onto the entire forming surface Ds of the die D.
  • the die D may move more than necessary in the Z direction.
  • the die movement amount calculating unit 56 is configured to calculate the Z-direction movement amount of the die D minimally required for winding the workpiece W onto the entire forming surface Ds of the die D.
  • FIG. 6 is a diagram for explaining a method of calculating a Z-direction movement amount of the die D.
  • FIG. 6 shows a cross section of the die D parallel to the Z-X plane.
  • Points P JL (S) and P JR (S) indicate the starting points of the paths P JL , P JR of the jaws J L , J R . Therefore, the starting points P JL (S) and P JR (S) indicate the positions of the reference points R JL , R JR of the jaws J L , J R before starting the stretch forming.
  • points P JL (F), P JR (F) indicate the ending points of the paths P JL , P JR of the jaws J L , J R . Therefore, the ending points P JL (F), P JR (F) indicate the positions of the reference points R JL , R JR of the jaws J L , J R after ending the stretch forming.
  • Dashed-dotted lines T L , T R indicate the tangent lines at the respective end edge portions of the forming surface Ds of the die D on the Z-X plane.
  • Points C L , C R indicate intersections between the paths P JL , P JR of the jaws J L , J R and the tangent lines T L , T R (corresponding to “first and second intersections” of the claims).
  • a Z-direction distance (corresponding to a “first vertical direction distance” of the claims) H L between the intersection C L and an apex (a point at the maximum height position of the forming surface Ds) D T of the die D corresponds to the Z-direction movement amount of the die D minimally required for a portion of the workpiece W closer to the jaw J L to be wrapped onto the forming surface Ds of the die D.
  • a Z-direction distance (corresponding to a “second vertical direction distance” of the claims) H R between the intersection C R and the apex D T of the die D corresponds to the Z-direction movement amount of the die D minimally required for a portion of the workpiece W closer to the jaw J R to be wrapped onto the forming surface Ds of the die D.
  • the intersections C L , C R between the paths P JL , P JR of the jaws J L , J R and the tangent lines T L , T R at the both respective end edge portions of the forming surface Ds of the die D are not necessarily located at the same height position (Z-direction position). In other words, the Z-direction distances H L , H R may be different.
  • the die D must be moved in the Z direction by the same movement amount as the larger Z-direction distance (H R in FIG. 6 ) so as to wrap both the portion of the workpiece W closer to the jaw J L and the portion of the workpiece W closer to the jaw J R onto the forming surface Ds of the die D. If the die D is moved in the Z direction by the same movement amount as the smaller vertical direction distance H L , the portion of the workpiece W closer to the jaw J R cannot brought into contact with the end edge portion of the forming surface Ds of the die D.
  • the die movement amount calculating unit 56 first calculates the intersections C L , C R between the paths P JL , P JR of the jaws J L , J R and the tangent lines T L , T R at the both respective end edge portions of the forming surface Ds of the die D based on the paths P JL , P JR of the jaws J L , J R calculated by the jaw path calculating unit 54 and the die shape acquired by the forming condition acquiring unit 52 .
  • the die movement amount calculating unit 56 then calculates the Z-direction distances H L , H R from the calculated intersections C L , C R to the apex D T of the die D.
  • the Z-direction distances H L , H R are compared to determine the greater one as the Z-direction movement amount of the die D.
  • the Z-direction movement amount of the die D may be calculated by using a straight line passing through two points on the end edge portions of the forming surface Ds of the die D as the tangent lines.
  • the Z-direction movement amount of the die D may be calculated by the following method. First, the intersections C L , C R are calculated between the paths P JL , P JR of the jaws J L , J R and the tangent lines T L , T R at the both respective end edge portions of the forming surface Ds of the die D in each of multiple Z-X planes at different Y-direction positions. A Z-direction distance is calculated between each of all the intersections C L , C R and the apex D T of the die D.
  • a maximum Z-direction distance is extracted from the multiple calculated Z-direction distances, and the extracted maximum Z-direction distance is defined as the Z-direction movement amount of the die D.
  • the control axis operation pattern calculating unit 58 of the control program creating apparatus 50 is configured to calculate the respective operation patterns of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 based on the forming conditions acquired by the forming condition acquiring unit 52 , the paths P JL , P JR of the jaws J L , J R calculated by the jaw path calculating unit 54 , and the Z-direction movement amount of the die D calculated by the die movement amount calculating unit 58 .
  • the control axis operation pattern calculating unit 58 calculates the respective operation patterns of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 for changing the respective positions and orientations of the jaws J L , J R and the die D, in accordance with the paths P JL , P JR of the jaws J L , J R from the respective initial positions and initial orientations of the jaws J L , J R and the die D acquired by the forming condition acquiring unit 52 .
  • control axis operation pattern calculating unit 58 calculates the respective operation patterns of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 such that the Z-direction movement amount from the initial position of the die D becomes equal to the movement amount calculated by the die movement amount calculating unit 56 (e.g., the Z-direction distance H R depicted in FIG. 6 ). Describing with reference to FIG.
  • the respective operation patterns of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 are calculated based on a portion of the path P JL of the jaw J L from the starting point P JL (S) to a point C L ′ and a portion of the path R JR of the jaw J R from the starting point P JR (S) to the intersection C R .
  • the point C L ′ is the point on the path P JL at the same position as the Z-direction position of the intersection C R as shown in FIG. 6 .
  • the operation patterns of the control axes necessary for the post-stretch of the workpiece W by the post-stretch amount are added to the operation patterns of the control axes calculated based on the calculation results of the jaw path calculating unit 54 and the die movement amount calculating unit 56 .
  • the operation patterns of the tension axes J L5 , J R5 for stretching the workpiece W by the tension axes J L5 , J R5 are added such that the workpiece W is stretched by the post-stretch amount given from the operator after the workpiece W comes into contact with the entire forming surface Ds of the die D as shown in FIG. 3D .
  • the operation patterns of the control axes necessary for stretching the workpiece W by the wrapping-time stretch amount are added to the operation patterns of the control axes calculated based on the calculation results of the jaw path calculating unit 54 and the die movement amount calculating unit 56 .
  • the operation patterns of the tension axes J L5 , J R5 for stretching the workpiece W by the tension axes J L5 , J R5 are added such that the workpiece W is stretched by the wrapping-time stretch amount from the start to the end of wrapping of the workpiece W onto the forming surface Ds of the die D.
  • the FEM analyzing unit 60 of the control program creating apparatus 50 is configured to execute the FEM analysis of the workpiece W by using the respective operation patterns of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 calculated by the control axis operation pattern calculating unit 58 .
  • the FEM analyzing unit 60 is configured to use the FEM analysis to calculate the deformation behavior of the workpiece W generated by the stretch forming apparatus 10 performing the stretch forming in accordance with the respective operation patterns of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 calculated by the control axis operation pattern calculating unit 58 .
  • the FEM analyzing unit 60 is configured to output the result of the FEM analysis to an operator via a display, for example. This allows the operator to determine whether the result of the FEM analysis is favorable.
  • the operator can know a partial thickness and a strain amount of the workpiece W after the stretch forming (a formed product). This enables the operator to confirm whether favorable operation patterns are calculated for the respective control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 . If the result of the FEM analysis is not favorable because of, for example, a significant local difference in the thickness or the strain amount, the operator can properly change the forming conditions such as a pre-stretch amount.
  • the operator determines that the result of the FEM analysis is favorable i.e., if the operator performs a corresponding operation to, for example, the input device such as a mouse and a keyboard
  • the respective operation patterns of the control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 calculated by the control axis operation pattern calculating unit 58 are fixed.
  • the control program creating unit 62 of the control program creating apparatus 50 is configured to create a control program for automatically controlling the respective operations of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 of the actual stretch forming apparatus 10 based on the respective operation patterns of the control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 calculated by the control axis operation pattern calculating unit 58 (determined as being favorable by the operator).
  • the control program creating unit 62 is configured to output the created control program as data.
  • the stretch forming apparatus 10 favorably and automatically winds the workpiece W onto the forming surface Ds of the die D. As a result, a favorable formed product is fabricated.
  • This embodiment enables the calculation of the paths of the relative positions and orientations of the respective jaws J L , J R with respect to the die D necessary for acquiring a favorable formed product from the stretch forming, i.e., the respective operation patterns of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 , in a short time. As a result, a burden of the operator can be reduced.
  • the orientations of the jaws J L , J R are changed such that the stroke directions (X JL and X JR directions) of the tension axes J L5 , J R5 match the extending directions of the workpiece W (the directions of the workpiece W extending from the die D toward jaws J L , J R ) while the stretch forming is performed.
  • the present invention is not limited thereto.
  • the jaws J L , J R are in an orientation (horizontal orientation) with the stroke directions of the tension axes J L5 , J R5 (the X JL and X JR directions) matching the horizontal direction and hold the workpiece W in a horizontally extending orientation. While the jaws J L , J R are maintained in the horizontal orientation, the die D is moved in the vertical direction (Z direction) and the workpiece is wound onto the forming surface Ds of the die D as shown in FIG. 7B .
  • the jaw path calculating unit 54 of the control program creating apparatus 50 regulates the movement of the jaws J L , J R in the Z direction and additionally regulates the rotation around rotation center lines extending in the directions that are horizontal directions orthogonal to jaw facing directions (i.e., Y JL and Y JR directions) to calculate the paths P JL , P JR of the relative positions and orientations of the jaws J L , J R with respect to the die D.
  • the control program can be created that automatically controls the respective operations of the multiple control axes J D1 to J D2 , J L1 to J L6 , J R1 to J R6 necessary for achieving a favorable formed product.
  • the forming surface Ds of the die D is in a curved shape
  • the present invention is not limited thereto.
  • a flat surface such as a forming surface Ds' of a die D′ as depicted in FIG. 8 may be available.
  • the present invention is applicable to any dies including a forming surface allowing a workpiece to wrap thereon.
  • the plate-shaped workpiece W wrapped onto the die D is in a flat plate shape
  • the present invention is not limited thereto.
  • the workpiece may be in a curved shape curving in a direction A 2 orthogonal to a jaw facing direction A 1 , instead of a flat plate shape.
  • the jaws are so-called curved jaws capable of clamping the curved workpiece W′ at the end edge portions opposite to each other.
  • the Z-direction movement amount of the die D calculated by the die movement amount calculating unit 56 is, in other words, a relative Z-direction movement amount of the die D with respect to the jaws J L , J R , as depicted in FIG. 6 .
  • the present invention is applicable to any stretch forming apparatuses having two jaws clamping a workpiece at respective end edge portions opposite to each other, a die disposed between the two jaws and coming into contact with the workpiece, and multiple control axes for changing the positions and orientations of the jaws and the die.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
US14/434,141 2012-10-16 2013-10-09 Stretch forming system and stretch forming method Abandoned US20150266077A1 (en)

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JP2012-229147 2012-10-16
JP2012229147A JP5961088B2 (ja) 2012-10-16 2012-10-16 ストレッチフォーミングシステムおよびストレッチフォーミング方法
PCT/JP2013/077517 WO2014061530A1 (ja) 2012-10-16 2013-10-09 ストレッチフォーミングシステムおよびストレッチフォーミング方法

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JP6834014B2 (ja) * 2017-09-28 2021-02-24 三菱重工業株式会社 ストレッチ成形装置及びストレッチ成形方法
CN111167919B (zh) * 2019-12-26 2021-05-07 中南大学 用于多曲率蒙皮件的拉形-电磁复合成形装置及其方法

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WO2014061530A1 (ja) 2014-04-24
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EP2910318A4 (en) 2016-06-29
JP2014079781A (ja) 2014-05-08

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