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
  • B21D19/00—Flanging or other edge treatment, e.g. of tubes
  • B21D19/08—Flanging or other edge treatment, e.g. of tubes by single or successive action of pressing tools, e.g. vice jaws
• • 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
• • 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
  • B21D53/00—Making other particular articles
  • B21D53/88—Making other particular articles other parts for vehicles, e.g. cowlings, mudguards

Definitions

• the invention relates to the field of stamping, more specifically to the forming of a part, in particular of bodywork or vehicle structure, by stamping a sheet blank.
• a punch and blanks When stamping a sheet blank, tooling comprising a die, a punch and blanks is usually used.
• the blanks are mounted laterally to the punch and sliding against elastic forces produced by springs.
• the matrix in the lower position, comprises lateral portions cooperating with the blank holders in order to clamp the edges of the sheet blank placed on the die. This clamping takes place during the descent movement of the punch to the die, as soon as the blanks contact the edges of the sheet blank, pressing them against the lateral portions of the die, against the elastic forces of the springs.
• the punch contacts the central portion of the sheet blank, it is deformed towards the die. The sheet then undergoes warping deformations generating tensile forces that can cause the sliding of the sheet along the blanks.
• the purpose of the blanks is to retain the blank of sheet metal and thereby generate deformations in elongation of the sheet to prevent the formation of undulations. Indeed, depending on the shape given to the stamping, swallowing sheet metal during the shaping can cause compressive forces by excess material, which can cause ripples. This is particularly the case when the stamping has a generally conical shape.
• the retention of the sheet blank by the blanks can sometimes lead to excessive extension deformations leading to too small thicknesses, or even breaks.
• the invention aims to overcome at least one of the drawbacks of the state of the art, in this case of the state of the art mentioned above. More particularly, the object of the invention is to propose a solution for forming open stampings.
• the subject of the invention is a process for shaping a workpiece by stamping a sheet blank, comprising the following steps: (a) placing the sheet blank on a drawing forming tool comprising: a matrix and a punch adapted to cooperate by engagement with the matrix; (b) bringing the die and the punch together in a direction of work to form the workpiece; remarkable in that in step (a), the sheet blank comprises at least one tab with at least one edge, and in step (b), the or each of the tabs is folded between the die and the punch and ensures retention of the sheet blank.
• the or each edge comprising the one or more tabs forms a final edge of the part.
• the sheet blank is generally elongated in a longitudinal direction, the or each edge comprising the tab or tabs being at one end, in said direction, of the sheet blank.
• the tooling comprises at least one blank holder disposed laterally to one of the punch and the die and able to clamp the sheet blank with the other of the punch and the die, the blanks being slidably mounted against an elastic force.
• step (b) the or at least one of the blanks clamps the longitudinal edges of the elongated sheet blank.
• the or at least one of the blanks clamps the leg or legs before it (s) is (b) folded (s) between the matrix and the punch.
• the leg or legs leave the blanks or blank before the end of step (b).
• the objective is that the leg or legs are of minimum size. It is therefore useful for the blank holder (s) to interact with the leg (s) only at the beginning of step (b).
• the one or more lugs may leave the blank holder (s) at the latest at the mid-race for forming the sheet blank by the die and the punch in step (b).
• the tab or tabs are folded in the working direction of the die and the punch.
• the or each of the tabs comprises a bent portion forming a radius of curvature of between 1 and 10 mm, preferably between 2 and 8 mm.
• the invention also relates to a tool for forming a workpiece by stamping a sheet blank according to the method of the invention, the tooling comprising: a die; a punch adapted to cooperate with the matrix by engagement in said matrix; and remarkable in that the die and the punch are configured to be able to bend the tab or tabs between the die and the punch, to ensure retention of the sheet blank during the forming of the piece.
• the tooling comprises at least one blank holder disposed laterally to the punch and able to clamp the sheet blank with at least one lateral portion of the die, the blank holder (s) being slidably mounted. against an elastic force.
• the lateral portion or portions of the matrix form one or more folding blades of the one or more lugs, respectively.
• the measures of the invention are interesting in that they make it possible to produce stamped parts by saving material while controlling the shaping by an adequate retention of the sheet during said shaping.
• FIG. 1 illustrates a sheet blank to be stamped by a method according to the invention
• FIG. 2 illustrates the principle of the tooling and the forming method according to the invention
• - Figure 3 is a schematic sectional view of the tool and the sheet blank according to a first step of the method according to the invention
• FIG. 4 corresponds to FIG. 3 at a later stage of the process according to the invention
• FIG. 5 corresponds to FIGS. 3 and 4 at a stage subsequent to that of FIG. 4;
• FIG. 6 corresponds to FIGS. 3 to 5, at a final stage of the process according to the invention
• Figure 7 illustrates in perspective the shape of the part formed successively to the steps of Figures 3 to 6.
• Figure 1 is a plan view of a blank sheet 2 to be formed by stamping with a tool and according to a method according to the invention.
• the sheet blank 2 comprises a central portion 21 with several edges or sides. It also includes a tab 2 2 on one of its edges.
• tab is meant a portion of sheet, integrally formed with the central portion, projecting from an edge of the central portion. It is thus a protruding portion, preferably generally flat with the central portion. Given that the portion is projecting, it has a width less than that of the edge from which it is derived.
• the sheet blank 2 extends in a longitudinal direction, and the tab 2 2 is located on an edge or side corresponding to an end of said blank along its longitudinal axis.
• FIG. 2 illustrates the principle of the stamping tool according to the invention and used to carry out the stamping process according to the invention.
• the tooling comprises a die 4, a punch 8 and one or more blanks 6. The latter or the latter are slidably mounted along the periphery of the punch 8, against elastic forces generated by unrepresented springs.
• the tooling and the process will be described in detail in connection with FIGS. 3 to 6 illustrating the successive steps of stamping the workpiece.
• FIG. 3 the profile of the die 4, whose end portions 4 1 and 4 2 come into contact with the sheet blank 2, can be observed. More specifically, the sheet blank 2, possibly preformed, is deposited on the blanks 6 while the tool is in the open position. The blanks 6 are in the upper position, that is to say greater than that of the punch, and the sheet blank can be deposited on the blanks 6.
• Figure 3 illustrates the situation where the matrix 4 has initiated its downward movement towards the punch 8 and where its end portions 4 1 and 4 2 are in contact with the sheet blank 2. The enlarged portion of Figure 3 shows that the tab 2 2 of the sheet blank 2 is clamped between the portion 4 1 of the die 4 and the blank holder 6.
• FIG. 4 illustrates the shape setting method of Figure 3 at a later stage, wherein the matrix 4 is more closer to the punch 8 to a point where the contact face 4 of the portion 1 of the matrix is aligned with the contact face vis-à-vis the punch 8, the thickness of the sheet close.
• the blank holder 6 has therefore begun its descent against the elastic forces of its springs.
• FIG. 5 illustrates a step of the method of FIGS. 3 and 4, at a step subsequent to that of FIG. 4, namely that the downward movement of the die 4 has the effect of folding the tab 2 2 downwards, in the space provided between the faces of the punch and the die which are vis-à-vis (visible to the enlarged area of Figure 3).
• the tab 2 2 thus folded then forms a brake for swallowing the sheet blank for the rest of the forming process. Indeed, the tab 2 2 forms a bent portion whose sliding along the corresponding edge of the punch generates a retaining force, in the manner of the blank holder.
• the blank holder 6 has more or almost no longer on said leg.
• the radius of curvature R of the edge of the punch 8 forming the bent portion of the lug 2 2 may be between 1 and 10 mm, preferably between 2 and 8 mm. Such values provide an interesting resisting force in that it is sufficient without blocking the slippage of the tab.
• FIG. 6 illustrates a final or near-final stage of the shaping process of FIGS. 3 to 5. The tab 2 2 has been deformed by sliding along the contact surface of the punch as a result of the traction forces generated by the deformation of the central portion 2 1 generated by the approximation of the die 4 and the punch 8.
• FIG. 7 illustrates in perspective the shape that the sheet blank progressively takes
• the representation in the upper position corresponds to the stage of FIG. 3 and the representation in the lower position corresponds to the part 10 after stamping.
• the piece 10 in this case, is a spar piece. This piece is usually elongated. It can be seen that the left end of the part, in its longitudinal direction, is open, namely that the corresponding edge 10 1 of the sheet blank thus formed should not undergo a cutting step (clipping). It can also be observed that the right end of the piece, always in its longitudinal direction, is semi-open, namely that it has a partially final edge 10 2 . The tab 2 2 is present on this edge 10 2 but occupies a small place and does not necessarily have to be cut.
• the longitudinal edges 10 3 and 10 4 in turn comprise portions intended to be cut. Indeed, these portions were used to retain the sheet transversely to its main direction during its shaping, which allowed to ensure satisfactory formatting.
• the deformation applied to the sheet in this direction is indeed important in comparison with the deformations in the longitudinal direction.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Shaping Metal By Deep-Drawing, Or The Like (AREA)

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Publications (1)

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Citations (3)

Family Cites Families (4)

• 2015
  • 2015-05-18 FR FR1554433A patent/FR3036299B1/fr active Active
• 2016
  • 2016-04-13 WO PCT/FR2016/050857 patent/WO2016185105A1/fr unknown
  • 2016-04-13 EP EP16729309.1A patent/EP3297777B1/fr active Active
  • 2016-04-13 ES ES16729309T patent/ES2901145T3/es active Active
  • 2016-04-13 CN CN201680028951.7A patent/CN107666974B/zh active Active

Patent Citations (3)

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