FR2819204A1 - Metal stamping procedure and press uses lubricating fluid feed for enhanced sheet metal shaping and less deformation - Google Patents

Abstract

The procedure for shaping metal components by pressure stamping incorporates a lubricating stage prior to the deformation stage, in which a fluid lubricant is fed by a pump (30) through pipes (32, 33) to one or more orifices (11) in the working face of the stamping tool (10) that makes contact with the metal workpiece. During the lubricating stage a droplet of lubricant is formed in the free air at the level of the orifice, which is connected to a lubricant reservoir (31) at atmospheric pressure and is located adjacent to a zone in which stresses are created in the metal workpiece, e.g. a corner.

Description

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The present invention relates to a stamping tool and a stamping press comprising such a tool.

In general, it relates to the stamping of pieces of metal or sheet metal, making it possible to deform the piece of metal to give it a determined shape.

 Many metal parts are thus produced by stamping, and for example metal strips used in household appliances.

 During stamping, the metal pieces can be, in certain portions, simply bent along a bending axis.

 They can also, in other portions, be stamped in the form of a wedge.

 The piece of metal is in these portions both folded and curved to match the wedge shape of a stamping tool, of greater or lesser radius.

 In these corner portions, there is a shrinkage and an elongation of the sheet.

 Traditionally, in order to facilitate the drawing of the metal in these portions subjected to high stresses of deformation of the metal, a drawing oil or a grease applied to the piece of metal to be stamped is used, for example by means of a roller. .

 The presence of a lubricating fluid on the sheet facilitates the deformation of the latter.

 However, this lubrication of the sheet is difficult and requires manual application of the oil on each piece of metal.

 In addition, the amount of stamping oil used is very large, stamping oil being frequently deposited on

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 parts of the metal part which are not directly affected by stamping.

 The present invention aims to solve the aforementioned drawbacks and to provide a stamping tool and a stamping press facilitating the lubrication of metal parts to be stamped.

 To this end, the present invention aims according to a first aspect, a stamping tool to deform a piece of metal.

 According to the invention, this stamping tool comprises at least one orifice for supplying a lubricating fluid opening onto a face adapted to come into contact with the metal part.

 Oil or grease can thus be deposited on the metal part directly by means of the stamping tool and no longer requires manual intervention.

 In addition, the Applicant has found that the presence of one or more orifices on one face of the stamping tool intended to come into contact with the piece of metal to be stamped does not modify the conditions of stamping of this piece.

 The deposit of oil at the level of the orifices can thus be relatively localized on the piece of metal, which considerably limits the quantity of oil used and the run-off of this on the piece of metal after stamping.

 According to a preferred characteristic of the invention, this orifice for supplying a lubricating fluid opens onto a leading face of the stamping tool.

 The face of the tool intended to come first into contact with the piece of metal during drawing is called the attack face.

 Generally, the piece of metal is held substantially without deformation on this leading face, the piece of metal being deformed against the sides of the stamping tool adjacent to this leading face.

 This arrangement of the lubrication orifice makes it possible to deposit a lubricating fluid on the piece of metal even before the deformation of the latter is started during stamping.

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 According to another preferred characteristic of the invention, this lubrication orifice opens in the vicinity of a stress-generating portion in the stamped metal part.

 The lubrication of the metal part can thus be located optimally in the portions of the metal part subjected to high stresses during stamping, and in particular to a shrinkage and an elongation of the metal.

 According to a particularly practical characteristic of the invention, ensuring uniform lubrication of the metal part, the stamping tool has several orifices for supplying a lubricating fluid, arranged on either side of a plane median of a wedge-shaped portion.

 According to a second aspect of the invention, a stamping press comprises a stamping die carried by an upper sole and a punch carried by a lower sole.

 According to the invention, the stamping die comprises a stamping tool in accordance with the first aspect of the invention.

 The lubrication of the metal part is thus integrated into the stamping die, around which the metal part is deformed.

 According to a preferred characteristic of the invention, this stamping press comprises a pump for supplying lubrication fluid to the orifices for supplying lubrication fluid to said matrix and means for controlling the operation of the pump suitable for bringing into operation start the pump when the press is closed and stop the pump when the press is open.

 This arrangement makes it possible to release oil on the metal part just before the stamping of the part. Conversely, the oil does not spread on the stamping die when the press is in the open position, in particular for supplying the press with a piece of metal to be stamped.

 Other features and advantages of the invention will appear in the description below.

 In the appended drawings, given by way of nonlimiting examples:

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- ta figure 3 est une vue en coupe selon la ligne III. III à la figure 2 ; - la figure 4 est une vue de dessous d'un outil d'emboutissage monté dans une presse d'emboutissage conforme à l'invention ; et - les figures 5 et 6 sont des vues schématiques en élévation d'une presse d'emboutissage conforme à l'invention, respectivement en position fermée et ouverte. - Figure 1 is a bottom view of a stamping tool according to an embodiment of the invention; - Figure 2 is a perspective view of the stamping tool of Figure 1;

- Your Figure 3 is a sectional view along line III. III in Figure 2; - Figure 4 is a bottom view of a stamping tool mounted in a stamping press according to the invention; and - Figures 5 and 6 are schematic elevational views of a stamping press according to the invention, respectively in the closed and open position.

 We will first describe with reference to Figures 1 to 3, a stamping tool 10 according to a first aspect of the invention.

 This stamping tool 10 is conventionally used to deform a piece of metal, and generally a sheet.

 As illustrated in FIG. 1, this stamping tool has a first face 10a, hereinafter called the leading face, intended to come into contact with the sheet metal part to be deformed during stamping.

métal, cette dernière étant déformée contre les flancs de l'outil adjacents à la face d'attaque 1 pa. This stamping tool 10 allows a piece of

metal, the latter being deformed against the sides of the tool adjacent to the leading face 1 pa.

 As illustrated in FIG. 1, at least one orifice, and here several orifices 11, open onto the leading face 10a.

 These orifices 11 are provided for supplying a lubricating fluid, generally a liquid oil, and depositing this oil on the piece of metal in contact with the leading face 1 pa.

 These orifices preferably open in the vicinity of one or more portions which, by their shapes, generate significant stresses in the piece of metal to be stamped.

 Here, two stress generating portions 12 are present in the stamping tool.

 These portions 12 are wedge-shaped. Consequently, the piece of metal to be stamped is both bent and deformed, along two axes

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 perpendicular to each other, so as to match the wedge shape 12 of the stamping tool.

 In fact, in these wedge-shaped portions 12, the metal sheet is both stretched and retracted during its stamping.

 In order to standardize the distribution of the oil on the piece of metal, several orifices 11 are arranged on either side of a median plane A of each wedge-shaped portion 12.

 Here, and in no way limiting, four orifices are arranged on either side of the corner 12.

 In order to supply the oil to each of these orifices 11, the latter are respectively connected by a pipe 13, as illustrated in FIG. 3, to means for supplying lubrication fluid.

 More particularly, each pipe 13 opens into a groove for supplying lubrication fluid 14 produced on the surface of a second face 1 Ob of the stamping tool 10.

 Here, this second face 10b of the stamping tool is the face opposite to the first leading face 10a of the tool.

 The pipes 13 thus extend in the thickness of the stamping tool.

 As well illustrated in FIG. 2, the second face 10b of the stamping tool 10 comprises a network of grooves 14 communicating with each other.

 Each pipe 13 opens into one of the grooves 14 so that a lubricating fluid circulating in these grooves 14 can supply the pipes 13 connected respectively to the orifices 11.

 Here, as illustrated in FIG. 3, these grooves 14 have a cross section in the shape of a semicircle.

 Near each wedge-shaped portion 12, a network of grooves 14 is formed, adapted to supply the four orifices 11 located near this wedge-shaped 12.

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 For example, two grooves 14a are arranged at right angles, their junction point P being substantially arranged in the median plane of the wedge-shaped portion 12.

 These two grooves 14a are connected at their free end respectively to two grooves 14b into which the pipes 13 open out from the orifices 11.

 Each groove 14b is thus formed of a straight segment, a pipe 13 opening at each end of the groove 14b.

 By way of example, these grooves 14 may have a width, in the plane of the second face 10b of the tool 10, substantially equal to 4 mm, and a depth, in a direction perpendicular to this second face 10b, of l '' order of 1.5 mm.

The pipes 13 and the orifices 11 opening onto the leading face 10a of the tool have a diameter of the order of 1 mm.

The stamping tool 10 is itself made of metal and the pipes 13 and the grooves 14 can be produced by a conventional electroerosion process.

 The stamping tool as described above is generally designed to be integrated in a stamping press, and to generally form the stamping die against which the sheet metal to be stamped is deformed in a single pass.

 The stamped part has stamping corner radii less than 4 mm and a stamped depth between 30 and 80 mm.

 Here, this stamping matrix comprises a stamping tool 10 as described above, comprising two wedge-shaped portions 12, and extended by two blades 15.

 These rectilinear blades 15 are conventional dies, intended only to bend the metal sheet during its stamping and requiring no addition of grease for the stamping of the metal.

 Although the illustration of Figure 4 is truncated, it is easily understood that a second stamping tool according to the invention can be

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 arranged opposite the first stamping tool 10 so that the stamping matrix forms a closed contour, substantially rectangular.

 As well illustrated in FIG. 5, this die 20 is fixed to a die-carrying plate 21, itself integral with the upper sole 22 of a stamping press 23.

 Opposite this upper part of the press 23, a lower sole 24 carries a punch holder sole 25 on which is mounted the clamp and the punch of the press 23.

 Conventionally, the sidewall clamp cooperates with the external contour of the matrix 20, while the punch cooperates with the internal contour of the matrix 20, and in particular with the wedge-shaped portions 12 of the stamping tool 10.

 This stamping press includes a supply pump 30 making it possible to supply the orifices 11 of the die 20 with lubricating oil.

This feed pump 30 cooperates with a reservoir 31 of lubricating oil.

As well illustrated in FIG. 4, the outlet of the pump 30 is connected by a pipe assembly 32,33 to the second face 10b of the stamping tool 10 of the die 20.

 More precisely, the pipes 33 for supplying the lubrication liquid open at right angles to the junction points P of the grooves 14 present on the second face 10b of the stamping tool.

 The oil thus distributed in the grooves 14 can feed the pipes 13 and the orifices 11 opening onto the other face 10a of the stamping tool 10.

déplacent avec celle-ci lors de l'ouverture et de la fermeture de la presse d'emboutissage 23. These pipes 32, 33, the pump 30 and the reservoir 31 are integral with the die-carrying plate 21 of the press so that they are

move with it when opening and closing the stamping press 23.

 In addition, as illustrated in FIGS. 5 and 6, control means 34, 35 are provided for controlling the operation of the pump 30.

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 Here, these control means consist of a contact arm 34 secured to the bottom flange 24 of the stamping press and of a contactor 35 cooperating with the pump 30.

presse est fermée tel qu'illustré à la figure 5, le bras de contact 34 actionne le contacteur 35 de pompe à huile 30 de telle sorte que quelques gouttes d'huiles sont libérées dans les gorges 14 et par conséquent, au niveau des orifices 11 débouchant de la face d'attaque 10a de l'outil d'emboutissage. In the low position of the stamping tool 10, that is to say when the

press is closed as illustrated in FIG. 5, the contact arm 34 actuates the oil pump contactor 35 so that a few drops of oils are released in the grooves 14 and therefore, at the orifices 11 emerging from the leading face 10a of the stamping tool.

 On the other hand, in the high position of the tool, that is to say when the press is open as illustrated in FIG. 6, the pump 30 is stopped.

 Thus, the lubricating oil does not spread over the die 20 when the press is open.

 A stamping press is thus obtained for which the lubrication of the pieces of metal to be stamped is greatly facilitated.

 Besides the fact that it is no longer done manually, the amount of oil used is very small compared to the traditional method of applying an oil with a roller, and is typically divided by 100.

 This lubrication integrated in the stamping matrix thus makes it possible to lubricate the metal part with each stroke of the stamping press.

 It is thus typically possible to stamp a piece of metal in the form of a strip, comprising at least one square portion whose internal corner is curved.

 Here, it is possible, for example, to stamp a rectangular strip comprising four curved internal corners.

 For example, the radius of the corners can be substantially equal to 4.5 mm.

 The piece of metal to be stamped can have a thickness of the order of 0.8 mm.

 Of course, many modifications can be made to the embodiment described above without departing from the scope of the invention.

Claims (11)

 CLAIMS 1. Stamping tool for deforming a piece of metal, characterized in that it comprises at least one orifice (11) for supplying a lubricating fluid opening onto a face (10a) adapted to come into contact with the piece of metal.  2. Stamping tool according to claim 1, characterized in that said orifice (11) opens onto a leading face (10a) of the stamping tool (10).  3. Stamping tool according to one of claims 1 or 2, characterized in that said orifice (11) opens in the vicinity of a portion (12) generating stresses in the piece of stamped metal.  4. Stamping tool according to claim 3, characterized in that said stress-generating portion (12) is a wedge-shaped portion (12) of the stamping tool (10).  5. Stamping tool according to claim 4, characterized in that it comprises several orifices (11) for supplying a lubricating fluid disposed on either side of a median plane (A) of the wedge-shaped portion (12).  6. Stamping tool according to one of claims 1 to 5, characterized in that each orifice (11) for supplying a lubricating fluid is connected by a pipe (13) to means for supplying lubricating fluid.  7. Stamping tool according to claim 6, characterized in that each pipe (13) opens into a groove (14) for supplying lubrication fluid produced on the surface of a second face (1 Ob) of the stamping tool (10).  8. Stamping tool according to claim 7, characterized in that said second face (10b) comprises a network of grooves (14) communicating with each other, adapted to supply lubrication fluid to several connected pipes (13) respectively to several orifices (11) for supplying lubricating fluid. <Desc / Clms Page number 10>  9. Stamping press comprising a stamping die (20) carried by an upper sole (22) and a punch (26) carried by a lower sole (24), characterized in that the stamping die (20) comprises a stamping tool (10) according to one of claims 1 to 8.

10. Stamping press according to claim 9, characterized in that it comprises a pump (30) for supplying lubricating fluid to the orifices (11) for supplying lubricating fluid to said matrix.

 (20) and control means (34, 35) of the operation of the pump (30) adapted to start the pump when the press (23) is closed and to stop the pump when the press (23) is open.  11. Use of a stamping press according to one of claims 9 or 10, characterized in that the piece of metal to be stamped is a strip comprising at least one square portion having a curved internal corner.