EP3932583A1 - Tool for punching a sheet or a multilayer assembly of sheets and corresponding punching method - Google Patents

Abstract

The invention relates to a punching tool intended to make holes in a part (T) formed from a sheet or a multi-layer assembly of sheets, for example a part (T) forming a vehicle body, comprising a door -punch (2) carrying a punch (3) for cutting a hole in the workpiece (T), said punch (3) for cutting being in one piece, and a punching die (4) arranged facing said punch holder ( 2), said punch holder (2) being designed to move said punch (3) for cutting towards said die (4) from a rest position to a working position in which said punch (3) for cutting cuts a hole in said piece (T) disposed between said punch holder (2) and said die (4), said cutting punch (3) being removably housed in a recess (21) formed in said punch holder (2 ) so that, when said punch holder (2) withdraws from the working position towards the rest position, said punch punch (3) for cutting separates from said punch holder (2) and remains housed in the hole drilled in said part (T).

Description

Technical area

The present invention relates to the field of working with materials, such as sheets.

More particularly, the invention relates to the field of punching sheet metal, in particular metal, more particularly to the field of punching tools.

The invention finds its use in particular in the automotive field, but also in any industrial field requiring perforations in sheets. It can, for example, be useful in the context of automobile body repair.

Prior art

Punching tools are used in industry to make perforations in sheet metal, for example in high strength sheet metal parts.

Punching is shearing on a closed contour, performed by a punch acting on a die. It is used to make holes and cut sides of complex shapes that are sometimes non-rectangular, therefore difficult or even impossible to achieve by shearing.

The cutting of vehicle body parts by punching has been a technique that has been used for many years. In fact, compared to a drilling process, the punching proves to be faster to perform, which therefore represents a saving of precious time in the cutting of such sheets.

In the automotive sector in particular, most of the punching sheets are high strength steel sheets (HR), called hard sheets, which reduce the weight of the vehicle while improving the safety of the occupants during operation. a shock. They conventionally exhibit a mechanical strength of between 200 and 1600 MPa.

Therefore, the wear of the punches used to pierce these sheets by punching is significant and it is necessary to replace them regularly, which is time consuming.

A sheet metal punching device has been proposed comprising a die and a punch which has a movable punching rod on which is mounted a punching ring which makes it possible to better control the shape of the hole created. Once the hole has been drilled, the washer falls on the side of the die with the drop formed during cutting and the punching rod crosses the drilled hole in the opposite direction so as to be extracted from it.

This device of the prior art is not satisfactory due to the fact that the crown, which has a small diameter, is difficult to handle and to place on the punching rod. It is also difficult to recover once it has fallen on the other side of the pierced sheet.

In addition, the crown is disposable because it wears out very quickly.

There is therefore a need to improve the existing technique so as to provide a punching device and method which makes it possible to punch high strength sheets without damaging the drilled holes and quickly replace the worn punches after the punching operation. punching.

Disclosure of the invention

The invention meets this need by proposing a punching tool intended to make holes in a part formed from a sheet or a multi-layer assembly of sheets, for example a part forming a vehicle body, comprising a holder. punch carrying a punch for cutting a hole in the workpiece, said punch being in one piece, and a punching die disposed opposite said punch holder, said punch holder being designed to drive said cutting punch towards said die d 'a rest position towards a working position in which said cutting punch cuts a hole in said part disposed between said punch holder and said die, said cutting punch being removably housed in an indentation formed in said punch holder so that, when said punch holder withdraws from the working position towards the rest position, said cutting punch becomes detached from said punch holder and remains housed in the hole drilled in said part.

The invention thus proposes to implement a one-piece punch removably mounted on a punch holder.

Only the one-piece punch is intended to pierce the sheet, the punch holder which carries the punch not being intended to at least partially pass through the hole cut by the punch and then to cross back through the hole in the opposite direction. The punch holder is therefore not configured to pierce the sheet but only to carry and move the punch, without engaging in the hole drilled by the punch.

The punch, which consists of a single piece, is mounted on the punch holder in a removable manner, without screwing, so that it ensures the cutting of the sheet initially, then that it is detached from the holder punch when the latter withdraws after cutting, the punch then remaining housed in the drilled hole.

As a result, but also by its dimensions and the material in which it is made, such a punch is very easy to position on the punch holder and easy to extract from the sheets forming the part to be drilled. It is also easy to find if it falls on the other side of the sheets.

The punch is more robust, because more massive, than the crowns of the prior art, and can be reused many times.

According to a particular aspect of the invention, said cutting punch has an undercut and an end, opposite to said undercut, said end being configured to slip into said cavity, said end having a shape complementary to that of said footprint.

According to a particular aspect of the invention, said end of said cutting punch has a substantially cylindrical shape.

• mise en position de ladite pièce à percer entre le porte-poinçon et la matrice dudit outil de poinçonnage disposés en regard l'un de l'autre ;
• poinçonnage de ladite pièce uniquement par le poinçon de découpage monobloc disposé sur la porte-poinçon par déplacement du porte-poinçon de sa position de repos à sa position de travail ;
• retrait dudit porte-poinçon par déplacement de ce dernier de sa position de travail à sa position de repos ;
• dégagement de ladite pièce dans laquelle est logée le poinçon de découpage ;
• retrait dudit poinçon de découpage de ladite pièce par poussée dudit poinçon de découpage au travers de la pièce.

The invention also relates to a method of punching a part formed from a sheet or a multi-layer assembly of sheets using a punching tool as described above, said method comprising the following successive steps :

• positioning of said part to be drilled between the punch holder and the die of said punching tool arranged opposite one another;
• punching of said part only by the one-piece cutting punch placed on the punch holder by moving the punch holder from its rest position to its working position;
• withdrawal of said punch holder by moving the latter from its working position to its rest position;
• release of said part in which the cutting punch is housed;
• withdrawing said cutting punch from said part by pushing said cutting punch through the part.

According to a particular aspect of the invention, the method comprises a preliminary step of positioning said cutting punch in said cavity of said punch holder.

According to a particular aspect of the invention, the step of withdrawing said cutting punch from said part is carried out by pushing said cutting punch through the part in the direction of drilling said hole.

According to a particular aspect of the invention, the method comprises a preliminary step of placing said part to be punched resting against said die.

Presentation of figures

• [Fig 1] est une vue en perspective d'un outil de poinçonnage selon un mode de réalisation de l'invention ;
• [Fig 2] est une vue en coupe d'un outil de poinçonnage placé sur un col de cygne, selon un mode de mise en œuvre de l'invention, illustrant l'étape de mise en position de la pièce en tôle(s) à percer ;
• [Fig 3] est une vue en coupe de l'outil de poinçonnage de la figure 2, illustrant l'étape de poinçonnage de la pièce en tôle(s) ;
• [Fig 4] est une vue en coupe de l'outil de poinçonnage précédent, illustrant l'étape de retrait du porte-poinçon ;
• [Fig 5] est une vue en coupe de l'outil de poinçonnage précédent, illustrant l'étape de dégagement de la pièce en tôle(s) ;
• [Fig 6] est une vue en coupe de l'outil de poinçonnage précédent, illustrant l'étape de retrait du poinçon de la pièce en tôle(s), et
• [Fig 7] est un schéma illustrant les différentes étapes du procédé de poinçonnage d'une pièce en tôle selon un mode de réalisation de l'invention.

Other aims, characteristics and advantages of the invention will emerge more clearly on reading the following description, given by way of simple illustrative example, and not limiting, in relation to the figures, among which:

• [ Fig 1 ] is a perspective view of a punching tool according to one embodiment of the invention;
• [ Fig 2 ] is a sectional view of a punching tool placed on a gooseneck, according to one embodiment of the invention, illustrating the step of positioning the sheet metal part (s) to be drilled;
• [ Fig 3 ] is a sectional view of the punching tool of the figure 2 , illustrating the step of punching the sheet metal part (s);
• [ Fig 4 ] is a sectional view of the preceding punching tool, illustrating the step of removing the punch holder;
• [ Fig 5 ] is a sectional view of the preceding punching tool, illustrating the step of disengaging the sheet metal part (s);
• [ Fig 6 ] is a sectional view of the previous punching tool, showing the step of removing the punch from the sheet metal part (s), and
• [ Fig 7 ] is a diagram illustrating the different steps of the punching process of a sheet metal part according to one embodiment of the invention.

Detailed description of an embodiment of the invention

The general principle of the invention is based on the use of a punching tool intended to make holes on the surface of a part formed from a single sheet or from a multi-layer assembly of sheets (c ' that is to say an assembly of two or more thicknesses of sheets, the sheets all being made of the same material (steel for example) or the sheets being in different materials (at least one steel sheet and at least one sheet aluminum, for example). Such a part is, for example, a body part of a vehicle. The punching tool comprises a punch holder which carries a one-piece punch removably housed in a recess formed in this holder -punch. In this way, when the punch holder moves from its working position, that is to say the piercing position of the workpiece towards its rest position, the cutting punch is released without action of the operator of the punch holder and remains attached to the punched part so that can then be pushed through the drilled hole. The punch being larger in size than the crown of the prior art, the positioning of the cutting punch on the punch holder for the following punching operation is thereby facilitated.

In the example described below, the punching tool is of the C gooseneck type. However, it could be in another form.

As shown on figures 1 to 6 , this punching tool therefore comprises a punch holder 2 supporting a one-piece cutting punch 3, and a punching die 4 placed opposite the punch holder 2.

Here, the punching die 4 is in the form of a cylindrical hollow body having a bore (otherwise called an orifice or discharge channel) allowing the passage of a punching drop after drilling of the part T consisting of a sheet or a multi-layer assembly of sheets. These sheets can be made of very hard steel, of the UHLE type (for “ultra high elastic limit”) for example, such as boron steel.

The two parts, namely on one side the punch holder 2 and on the other the punching die 4 are connected by means of a gooseneck 9. This gooseneck 9 here forms a C-shaped frame. allowing the two parts to be held in place relative to each other.

So as to be maintained on the gooseneck 9, the punch holder 2 which is generally cylindrical comprises a first retaining element 20 able to cooperate with a first housing implemented at one end of the gooseneck.

Likewise, and so as to be held on the gooseneck 9, the punching die 4 comprises a second retaining element 40 able to cooperate with a second housing implemented at the opposite end of the gooseneck.

The figure 1 shows punch holder 2, punch die 4 and punch 3 when disassembled from gooseneck 9. All of these are cylindrical.

The punch holder 2 is movably mounted and it is designed to move from a rest position to a working position to drive the punch 3 in movement towards the die 4, along a displacement axis A, until the punch 3 is introduced into the piece of sheet metal T arranged between the punch holder 2 and the die 4 in order to cut a hole there.

By cutting the sheet metal part (s) T, the punch 3 pushes a scrap of the sheet metal part, corresponding to the material removed by drilling, into the bore of the punching die 4.

The driving in movement of the punch holder 2 and of the punch 3 can, according to the embodiments, be carried out by means of an actuator (not shown in the figures).

This punch 3, which is in one piece, is implemented here in the form of a rod with a diameter of 6 to 10 mm, for example, which can be made of resistant steel.

The punch 3 has an undercut 30 making it possible to drill the sheet metal part T, in the working position.

According to the invention, the punch 3 is removably housed in a recess 21 formed in the punch holder 2 so that, when the punch holder 2 moves from its working position to its rest position, the punch 3 separates from the punch holder 2 and remains integral with the sheet metal part (s) T (the punch 3 remains housed in the drilled hole).

By virtue of its dimensions and the material in which it is made, the punch 3 is reusable and easier to recover after the punching operation.

In other words, the punch 3 is placed in the recess 21 of the punch holder 2, and this without clamping or screwing, so that the punch 3 is free in translation along an axis of movement of the punch holder 2 which corresponds to the displacement axis A.

This imprint 21 is, as illustrated on the figure 1 , arranged opposite the holding element 20 of the punch holder 2.

The clearance between the recess 21 and the punch 3 must be sufficient for the punch to separate from the punch holder when the latter is withdrawn once the punching has been carried out. This play should not be too great either to prevent the punch from falling from the punch holder before punching and to ensure efficient punching of the sheet to be drilled. The external diameter of the punch can thus be slightly smaller than the internal diameter of the indentation 21.

In a variant, the punch 3 can be retained in the recess 21 of the punch holder 2 by friction. In other words, the punch 3 is retained in the cavity 21 by friction. This friction force is chosen so that, when the cutting punch 3 has pierced the hole and is located in the latter, it can become detached from the punch holder 2 when the latter withdraws by moving in the opposite direction. of the drilling direction.

More particularly, and in this embodiment, the punch 3 has an end 31, opposite to the undercut 30, which is configured to slip into the recess 21.

So as to facilitate this sliding, and in the illustrated embodiment, the end 31 and the recess 21 have a respective substantially complementary shape.

Here the end 31 of the punch 3, and therefore the indentation 21 of the punch holder 2, each have a substantially circular section, the two sections being complementary.

However, in other embodiments, one could provide an indentation and a punch end having a different section, for example a triangular, square, or more generally polygonal shape, the respective sections of the indentation and of the end. punch being complementary.

We now present, in relation to the figures 2 to 7 , an embodiment of the method 100 for punching a piece T formed from a single sheet or from several layers of sheets using a punching tool according to the invention.

• mise en position 101 de la pièce T à percer entre le porte-poinçon 2 et la matrice 4 de l'outil de poinçonnage qui sont situés en vis-à-vis l'un de l'autre ;
• poinçonnage 102 de la pièce T par le poinçon uniquement de sorte à percer un trou par déplacement du porte-poinçon 2 de sa position de repos à sa position de travail (de la gauche vers la droite ici) dans un premier sens de déplacement ;

• retrait 103 du porte-poinçon 2 par déplacement de ce dernier de sa position de travail à sa position de repos (de la droite vers la gauche) dans un deuxième sens de déplacement opposé au premier sens de déplacement, le poinçon 3 se désolidarisant du porte-poinçon et restant dans le trou de la pièce T poinçonnée ;
• dégagement 104 de la pièce T poinçonnée dans laquelle est retenu le poinçon 3 ;
• retrait 105 du poinçon 3 de la pièce T poinçonnée par poussée du poinçon 3 au travers de la pièce T.

According to the invention presented, and as illustrated in figure 7 , this method comprises the following successive steps:

• placing the piece T to be drilled in position 101 between the punch holder 2 and the die 4 of the punching tool which are located opposite one another;
• punching 102 of the piece T by the punch only so as to drill a hole by moving the punch holder 2 from its rest position to its working position (from the left to right here) in a first direction of movement;

• withdrawal 103 of the punch holder 2 by moving the latter from its working position to its rest position (from right to left) in a second direction of movement opposite to the first direction of movement, the punch 3 separating from the holder -punch and remaining in the hole of the punched T part;
• clearance 104 of the punched part T in which the punch 3 is retained;
• withdrawal 105 of the punch 3 from the punched part T by pushing the punch 3 through the part T.

The figure 2 illustrates in section the punching tool after the step of positioning 101.

As illustrated in this position, the punch holder 2 is in the rest position at a distance from the part T which itself bears against the punching die 4. The punch holder 2, the punch 3, and the punching die. punching 4 are aligned along the axis A of displacement.

The figure 3 illustrates in section the punching tool during the punching step 102 by displacement of the punch holder 2 from its rest position to its working position along the axis A of displacement.

As illustrated, in this position, the punch holder 2 is in the working position and the punch 3 is in contact with the part T which is drilled at the location of the point of contact between the punch 3 and the part T on the axis A of displacement. In this position, the scrap sheet (not visible) has fallen into the punching die. The punch 3 is therefore housed in the hole which has just been drilled in the part T. It is noted that the punch holder 2 does not pass, even partially, the part T and therefore does not engage in the hole drilled by the punch 3.

The figure 4 illustrates in section the punching tool during the step of withdrawal 103 of the punch holder 2 by displacement of the latter from its working position to its rest position along the axis A of displacement.

As illustrated, in this position, the punch holder 2 is between the working position and the rest position. In other words, it has moved from the working position and is heading towards the resting position. The punch 3 is here still housed in the hole which has just been drilled in the part T and is no longer in contact with the punch holder 2.

In other words, the punch holder 2 moves back from its working position to its rest position and is moved away from the part T, the punch 3 being housed and retained in the newly drilled hole in the part T.

It should be noted that the punching 102 of the part T can, for example, make it possible to obtain a hole with a diameter of between 6 and 10mm. Larger or smaller holes can be made.

Such a hole can, for example, make it possible to pass a rivet or other means of fixation.

The figure 5 illustrates the step of release 104 of the part T once the latter has been punched.

As illustrated in this position, the punch holder 2 is in the rest position at a distance from the part T which itself is released from the gooseneck and is no longer resting against the punching die 4. The punch holder 2 and the punching die 4 are still aligned along the axis A of movement, while the punch 3 is still housed in the hole which has just been drilled in the part T.

The figure 6 illustrates the step 105 of removing punch 3 from part T.

As illustrated, the punch holder 2 is in the rest position at a distance from the part T which itself is released from the gooseneck and is no longer resting against the punching die 4. The punch holder 2 and the punching die 4 are always aligned along the axis A of displacement. The punch 3 can be released from the part T by making it pass through the hole in the direction of the drilling of the part T (that is to say from left to right in the figures).

In other words, in this embodiment, and as illustrated in figure 6 , the step of withdrawing the punch 3 from the part T is carried out by pushing the punch through the part T in the direction of drilling the hole.

Therefore, by passing the hole through the punch 3 in the drilling direction, that is to say by not doing it in the reverse direction of drilling as in the prior art, avoids risks of deformation of the edge of the hole, or the risk of the punch jamming in the hole.

As shown in figure 7 , the punching process can also comprise a preliminary step 106 of placing the punch 3 in the recess 21 of the punch holder 2.

It should be noted that, according to the embodiments, the installation of this punch can be carried out before or after the installation of the punch holder on the gooseneck, that is to say before or after the positioning of the part to be drilled between the punch holder and the die of the punching tool arranged opposite one another.

In addition, and as illustrated in this same figure 7 , the punching process can additionally comprise a preliminary step 106 of placing the part resting against the punching die 4. This part may not be placed resting against the punching die, but will be pressed against the latter under the effect of the advancement of the punch.

Furthermore, the punch may have a shape other than a cylindrical shape.

Claims (7)

Punching tool intended to make holes in a part (T) formed from a sheet or a multi-layer assembly of sheets, for example a part (T) forming a vehicle body, comprising a punch holder (2) carrying a punch (3) for cutting a hole in the part (T), said cutting punch (3) being in one piece, and a punching die (4) arranged opposite said punch holder (2), said door -punch (2) being designed to drive said cutting punch (3) towards said die (4) in movement from a rest position to a working position in which said cutting punch (3) cuts a hole in said part (T) disposed between said punch holder (2) and said die (4), said cutting punch (3) being removably housed in a recess (21) formed in said punch holder (2) so that that, when said punch holder (2) withdraws from the working position towards the rest position, said cutting punch (3) is separates from said punch holder (2) and remains housed in the hole drilled in said part (T). Punching tool according to claim 1, characterized in that said cutting punch (3) has an undercut (30) and an end (31), opposite to said undercut (30), said end (31) being configured to slip into said cavity (21), said end (31) having a shape complementary to that of said cavity (21). Punching tool according to claim 2, characterized in that said end (31) of said cutting punch (3) has a substantially cylindrical shape. Method (100) of punching a part (T) formed from a sheet or a multi-layer assembly of sheets using a punching tool according to any one of claims 1 to 3, characterized in that said method comprises the following successive steps: - positioning (101) of said part (T) to be drilled between the punch holder (2) and the die (4) of said punching tool arranged opposite one another; - punching (102) of said part (T) only by the cutting punch (3) arranged on the punch holder (2) by moving the punch holder (2) from its rest position to its working position; - withdrawal (103) of said punch holder (2) by displacement of the latter from its working position to its resting position; - disengagement (104) of said part (T) in which the cutting punch (3) is housed; - withdrawal (105) of said punch (3) from said part (T) by pushing said cutting punch (3) through the part (T). Method (100) of punching a part (T) according to Claim 4, characterized in that it comprises a preliminary step (106) of positioning said cutting punch (3) in said cavity (20) of said door - punch (2). A method (100) of punching a part (T) according to claim 4 or 5, characterized in that the step of withdrawing said punch (3) of cutting said part (T) is carried out by pushing said punch (3). ) cutting through the part (T) in the direction of drilling said hole. Method (100) of punching a part (T) according to one of claims 4 to 6, characterized in that it comprises a preliminary step (107) of placing said part (T) to be punched in abutment against said said part (T). matrix (4).

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