EP0672479B1 - Punching apparatus for metallic profiles - Google Patents

Description

The present invention relates to a punching tool intended in particular to produce on a continuous and elongated tubular metal profile, in a closed section on itself thereof, a clear opening of given contour and in particular of rectangular shape and preferably two openings of this kind, identical and facing one another on two parallel faces of this profile, in particular for the mounting of an accessory to be fixed thereon.

More particularly still, the invention relates to a tool of this kind, capable of piercing a very long profile which itself has a generally rectangular section, in particular of the type of those used to constitute the chassis of a fixed frame or of a movable opening of a door, window or the like, in order to mount in the openings made in this profile, at a suitable distance from its ends, the shell of a handle or of a lock for controlling or immobilizing the opening - screw of the frame, making it possible to ensure its pivoting or sliding movement relative to the latter.

Traditionally, these openings, which have two large sides parallel to the longitudinal direction of the metal profile, are produced by milling, which constitutes a long and relatively expensive operation, such a process being nevertheless until now necessary due to the relative position of the openings to be made along the length of the profile, these openings being located at a generally significant distance from the open ends of the latter and not in principle making it possible to implement the conventional punching technique faster and at minimal cost .

Indeed, this last technique normally requires that the punching tool which cuts by pressing from the outside the metal sheet of the profile according to a movement controlled perpendicular to the surface to perforate, either associated with a die or anvil placed on the other side of the sheet to prevent the metal from being carried away or torn towards the inside of the profile when the tool punctures the surface to be cut.

In addition, if the very structure of the profile includes internal webs perpendicular to the faces where the openings are to be made (see for example FR-A-2644202), suitable for supporting the pressed sheet metal and cut simultaneously by the punch limiting the inconvenience aforementioned, the relatively large metal chip for the suitable housing of the accessory to be mounted in this opening, may fall inside the profile, which leads to difficulties in obtaining its subsequent removal and causes a loss of time .

Furthermore, even in the previous case, the use of a usual punching tool cannot avoid the deformation of the sheet along the short sides of the opening which are more or less forced towards the inside of the profile, the opening does not have a perfectly regular profile and in the plane of the surface of the profile, which causes difficulties for the subsequent mounting of the accessory.

Finally, when, as frequently envisaged, it is necessary to make two facing cuts, strictly identical and in particular formed strictly in correspondence on the two opposite faces of the profile, the conventional solution by punching, which consists in positioning the tool by means of '' a preliminary tracing carried out on these faces, can lead to an imperfect alignment, with need for a later adjustment during the assembly of the accessory, which is not always possible and in all cases, involves a loss of time important, by increasing the cost of the supply.

The subject of the present invention is a punching tool which overcomes these drawbacks, by making it possible to obtain clean cuts, in particular of rectangular shape, with two long sides and two short sides respectively parallel in a metal section of great length and whose longitudinal direction is that of the long sides of the cutouts, these being produced quickly and efficiently with precise positioning in two opposite parallel faces of the profile to obtain their exact facing.

To this end, the tool considered, for producing in a very long tubular metal section with closed section on itself and having two opposite parallel faces arranged horizontally, with one and preferably two identical rectangular openings, respectively in the one and the other of these faces, substantially in the middle of the length of the profile, the long sides of these openings extending in the longitudinal direction of the profile, which internally comprises at least two parallel webs, perpendicular to the opposite faces and parallel to the long sides of the openings, the short sides of which are substantially equal to the distance which separates these sails, a tool which comprises a punch of generally parallelepipedal shape, the sharp lower longitudinal edges of which are parallel to the long sides of the openings, the width of the punch being equal to that of the short sides while its long ur is less than that of the long sides, the punch being integral with a movable control piston inside a fixed support, having an open lateral groove for positioning the profile under the punch in line with an opening to be produced by vertical insertion of the latter from top to bottom in the profile through the face to be cut under the effect of the displacement of the piston, the latter having a dimension in length less than that of the punch, which includes upper transverse edges also sharp to successively form the short sides of the opening following longitudinal movements of the profile in the groove until it abuts on the piston prior to the return movement thereof, bringing the punch to the of the profile.

The punching tool thus arranged makes it possible to carry out, firstly and following a displacement from the top to the bottom controlled by the piston, a blank for cutting a chip in the upper face of the profile disposed horizontally in the groove of the support, along the long sides of the opening to be made, the cutting of the sheet occurring in the immediate vicinity of the internal webs of the profile which for them play the role of an internal matrix, this cutting being obtained along a clean line , following the plans of the two sails respectively.

Simultaneously, the lower transverse edges of the punch cut the sheet metal parallel to the short sides of the opening but, according to lines located towards the inside of the opening, due to the length of the punch less than that of the long sides of the latter. , these lines and the adjoining part of the sheet on each side of the punch being slightly forced towards the inside of the profile.

In a second step, the punch, engaged inside the profile, after crossing the sheet in the corresponding face, is moved to the right or to the left by a determined distance, this transverse movement being authorized due to the more limited length of the piston compared to that of the punch.

At this instant and in a third step, the movement of the piston is reversed to produce a displacement of the punch from bottom to top, the upper lateral edges of the latter coming to cut the corresponding fraction of the sheet at the precise location of the small side. from the opening, the relatively limited area of this fraction vis-à-vis that of the chip carried during the descent of the tool, making it possible to obtain sharp lines, not only along this short side but also in the corresponding extension of the long sides of the 'final opening.

In a fourth step, the punch is again engaged by a downward movement of the piston inside the formed blank, then moved in the direction opposite to that adopted in the third step, the return from the bottom to the top of the punch under the control of the piston, carrying out, in the same manner as indicated above, the cutting of the corresponding fraction of the sheet and the formation of the second short side.

An opening is thus produced in one of the faces of the sheet which has a perfectly rectangular profile, without sinking or deformation of the remaining metal, facilitating for the reasons already specified, the subsequent mounting of an accessory and in particular of a shell handle or the like in the profile.

According to another advantageous characteristic, the cross section of the punch has, along its short sides, a profile consisting of two contiguous zones substantially in an arc towards the inside thereof, these zones being symmetrical to one another relative to the vertical median plane of the punch and meeting at a point in this plane, to form a longitudinal central edge located in this plane below the common level of the two lower lateral edges of the punch.

This particular structure of the lower surface of the punch, with its two lateral edges extending in its longitudinal direction and a more projecting central edge, allows an attack of the sheet in the upper face of the profile when the piston descends in the first aforementioned time, such that the chip produced has a slightly curved transverse profile, because of the force exerted in the middle part of this chip by this central edge, this deformation having the effect of slightly reducing the width of the chip and consequently preventing it from getting stuck inside the profile, between the side sails and the opposite sides thereof.

According to another characteristic of the invention, the upper transverse edges of the punch are inclined on the horizontal plane, so as to cut the sheet from one end to the other of the short sides of the opening during the return movement of the punch .

This particular shape of the cutting edges formed on the top of the punch, on each side of the control piston, has the advantage of being able to cut along the short sides of the opening the corresponding sheet metal fractions previously forced inwards, according to perfectly clear lines and corresponding to precise dimensions.

Advantageously, the fixed support comprises two vertical lateral guides, spaced from each other by the length of the punch along its long sides, against which the short sides of the latter slide during its downward and return movements, these guides forming support dies during the cutting of the sheet metal fractions when the punch is raised.

Preferably also and according to yet another characteristic of the tool considered, the difference in length between the punch and the piston is equal to the displacements of the profile in the open groove of the support, prior to the upward movement of the punch.

In a particularly advantageous embodiment, the fixed support comprises in its open groove receiving the profile, a movable stop, capable of disappearing when the profile is engaged in this groove, this stop being able, on the other hand, to penetrate into a first opening made in one side of the profile after turning over this 180 ° on itself and substitution of one of the other for its horizontal faces, so as to allow the position of the profile to be indexed relative to the first opening and to make a second opening in the opposite side, located exactly opposite the first.

The invention also relates to the method implemented by means of the punching tool considered, which consists in placing the profile in the open groove of the fixed support so that it has one of its horizontal faces opposite the punch. in the raised position, to control the descent of the punch vertically from top to bottom to form the blank of the opening in this face, with its long sides parallel to the parallel webs of the profile, to move the profile laterally to the right or to the left in a first direction, so that the corresponding lateral side of the blank of the opening comes to rest against the piston above the punch, to control the movement of the punch from the bottom upwards to complete the cutting from the short side of the opening, to cause a new displacement from the top to the bottom of the punch, to move the profile laterally in the opposite direction from the first and to re-order the movement of the punch from bottom to top to complete the opening along its opposite small side.

• La Figure 1 est une vue en perspective d'un élément de profilé tubulaire, de grande longueur, dans lequel on souhaite réaliser une et de préférence deux découpes identiques, en regard dans ses faces opposées, sensiblement dans la partie médiane de ce profilé.
• La Figure 2 est une vue en coupe transversale à légèrement plus grande échelle du support fixe du piston mobile et du poinçon porté par ce piston, permettant de réaliser les découpes du profilé.
• La Figure 3 comporte neuf schémas de principe, repérés respectivement de a à i, permettant de mieux expliciter la manière dont le poinçon réalise les découpes du profilé.
• La Figure 4 est une vue en perspective à plus grande échelle des éléments représentés sur la Figure 2.
• La Figure 5 est une vue en perspective à encore plus grande échelle d'une partie de la Figure 4.

Other characteristics of a punching tool established in accordance with the invention will become more apparent from the following description of an exemplary embodiment, given by way of non-limiting example, with reference to the appended drawings in which:

• Figure 1 is a perspective view of a tubular profile element, of great length, in which it is desired to make one and preferably two identical cuts, facing in its opposite faces, substantially in the middle part of this profile.
• Figure 2 is a cross-sectional view on a slightly larger scale of the fixed support of the movable piston and of the punch carried by this piston, making it possible to cut the profile.
• Figure 3 has nine block diagrams, marked respectively from a to i, to better explain how the punch performs the profile cuts.
• Figure 4 is an enlarged perspective view of the elements shown in Figure 2.
• Figure 5 is an even larger scale perspective view of part of Figure 4.

In FIG. 1, the reference 1 generally designates an elongated and continuous metal profile, of the kind of those commonly used in aluminum carpentry for making frames for doors, windows or the like.

Such a profile has, in itself known, a tubular structure, comprising two opposite parallel faces, respectively 2 and 3, braced by means of two equally parallel webs, respectively 4 and 5, extending perpendicular to the faces 2 and 3. The latter extend beyond the sails 4 and 5 and comprise possibly grooved parts such as 6, 7 and 8, the detail of the latter not important to the present invention. The sails 4 and 5 define with the opposite parallel faces 2 and 3 an internal housing 9, completely surrounded by these elements.

Under these conditions, it is easily understood that in order to produce in the section 1, the length of which may in practice have several meters, an opening 10, substantially in the middle part of this section, through one of the opposite parallel faces 2 or 3, it it is not practicable to introduce inside the profile, in particular into the housing 9, a structure forming a support matrix, against which a support tool can lean punching coming to cut in the sheet of the profile the opening 10, the latter being generally intended for mounting on the profile of an accessory and in particular of a shell of a handle or of a lock, to be attached to the profile when this constitutes a part of the frame of a frame or door or window opening.

The problem thus posed is all the more difficult to solve since, in addition to the aforementioned opening 10, for example formed in the face 2 of the profile 1, it is necessary, for the mounting of said accessory, to produce on the opposite face 3 a second opening 11 which is identical to the first and created strictly opposite it to be in exact correspondence with it.

The implementation of a conventional punching tool, without special precautions, is not suitable, because of the deformations that its use implies, due to the absence of a matrix or anvil capable of being disposed of the other side of the face 2 or 3 of the profile in which the opening 10 or 11 is formed, the edges of the latter being therefore irregular or forced towards the housing 9 when the sheet is cut by the punch, the corresponding deformation introducing difficulties to then carry out the correct mounting of the accessory on the profile.

The usual use of a milling process for making cuts 10 and 11 involves various constraints, requiring in particular precise preliminary outlines of the zones in which the openings must be made, which is difficult to put into practice and in any case, the cost of the installation will strike sharply.

The punching tool according to the present invention, of which Figures 2, 4 and 5 illustrate more particularly the structure, makes it possible to avoid these drawbacks, by ensuring the production of one or even two openings 10 and 11 in the opposite faces 2 and 3 of the profile 1, which is simple to implement, allows precise cuts exactly to the desired dimensions and such that, when the profile must have two facing openings, these are strictly in correspondence and have entirely identical dimensions.

In the embodiment shown in the drawings, which corresponds to a preferred and practically exclusive implementation of the invention, the openings 10 and 11 have a rectangular profile, this precise shape not however being completely limiting.

In this case, each opening has two large parallel sides, respectively 12 and 13, these sides extending in the longitudinal direction of the profile and preferably in the immediate vicinity, respectively of the parallel sails 4 and 5, perpendicular to the faces 2 and 3 of the profiled for the reasons explained below. These openings 12 and 13 also have short transverse sides, respectively 14 and 15, perpendicular of course to the longitudinal sides 12 and 13, these transverse sides 14 and 15 therefore being perpendicular to the webs 4 and 5, their common dimension being substantially equal. at the distance between these sails.

In FIG. 2, then in FIGS. 4 and 5 is more particularly illustrated the punching tool according to the invention, making it possible to make the openings 10 and 11 in the faces 2 and 3 of the profile, without using a matrix or anvil of back pressure arranged in the housing 9 in line with the areas where these openings must be made.

As illustrated in FIG. 2, the tool mainly comprises a punch 16 the shape and implementation of which are specified below, this punch 16 being integral with a piston 17, itself fitted into a control block 18 allowing by means of a jack 19 or other to exert an effort on the punch 16, either from top to bottom in the vertical direction in the drawings, or vice versa from bottom to top.

The control unit 18 is guided in its movement by means of rods slidably mounted in bores 21 of a fixed support 22, which has a groove 23 open laterally and into which the profile 1 can be introduced beforehand. position such that it has its opposite faces 2 and 3 in horizontal parallel planes, perpendicular to the vertical direction of movement of the punch 16.

The fixed support 22 also comprises a retractable stop 24 which, in the example schematically illustrated in FIG. 2 comprises an arm 25 articulated around a horizontal axis, this stop being permanently subjected to the action of a spring of thrust 27, so that a ball-shaped projection 28 provided on the arm 25 can come to emerge in the groove 23 when the latter does not include the profile 1, conversely disappear outside of this groove when the profile pushes the stop by the horizontal face 3, in the position illustrated in FIG. 2.

Note, as will be specified below, that if the profile 1 is turned over on itself by 180 ° so that the face 2 located initially at its upper part in the drawing and in which will have been formed a opening 10 as shown in Figure 1, comes to replace the face 3, the stop 24 may in this case bring out the projection 28 of the arm 25 inside this opening 10, allowing in this case an indexing of the position of the profile vis-à-vis the punch and the piercing of its face 3 then opposite this punch, to obtain the second opening 11, the latter being produced in precise coincidence with the position of the first opening 10.

FIGS. 4 and 5 illustrate in more detail the profile of the punch 16. The latter, of generally parallelepiped shape, preferably comprises two longitudinal cutting edges, respectively 29 and 31, which extend parallel to the direction of the profile 1, these edges being joined in the lower part of the punch by two zones, respectively 30 and 32, in an arc of a circle, symmetrical with each other relative to the median plane of the tool and which join to form a central edge 33, parallel to the longitudinal edges 29 and 31, but which, by construction, are at a level slightly lower in the vertical direction to the latter, that is to say made more protruding outward from the punch under this one.

The punch also comprises in its upper part two transverse edges, respectively 34 and 35, also sharp, these edges being preferably inclined on the horizontal plane, from one end to the other thereof.

The punch 16 is integral with the piston 17, these two parts preferably coming from manufacture, by machining or foundry, in one piece, or if necessary attached and fixed to each other by any suitable means.

The width of the punch 16 corresponds by construction to that of the openings 10 or 11 to be produced in the profile 1, and corresponds to that of the short sides 14 and 15 thereof. On the other hand, the length of the punch is such that it is slightly less than that of the long sides 12 and 13 of these same openings.

The piston 17 in turn has a width which corresponds to that of the punch. On the other hand, its length is again less than that of this punch, as clearly illustrated in Figure 4, the difference in the lengths of these two parts of the punching tool being determined so that this difference, added to the length of the punch on either side of its lateral ends, leads to an overall dimension which corresponds to that of the long sides 12 and 13 of the openings 10 or 11.

In FIG. 4, the reference 36 represents the metal chip created in the surface 2 (or 3) of the profile 1 by an up and down movement of the piston 17 and of driving in the punch 16 piercing and crossing this surface, this chip is collecting in the bottom of the housing 9, from which it can be subsequently extracted, thanks in particular to its slight reduction in width with respect to the distance which separates the long sides 12 and 13 from the blank of the opening 10 or 11 produced, caused by the particular shape of the underside of this punch and in particular of the relative arrangement of the edges 29 and 31 on the one hand, 33 on the other hand, the chip 36 curving slightly on itself during of its creation and its separation from the metal sheet from which it comes.

The operation of the punching tool according to the invention is easily deduced from the foregoing explanations and in particular from the various steps schematically illustrated in Figures 3a to 3i.

In Figure 3a, the section 1 is assumed to be engaged in the open groove of the fixed support with its opposite parallel faces, 2 and 3 respectively, arranged in horizontal planes.

Since these faces are full and continuous, the engagement of the profile in the groove automatically causes the abutment 24 to be erased (FIG. 2), the lever 25 and the ball-shaped projection 28 being pushed back against the spring 27 by the plane-to-plane sliding of the face 3 against the bottom of this groove.

In this preliminary phase, the punch 16 carried by the piston 17 is above the profile 1, which is positioned under the punch 16 in line with the first opening 10 to be produced in its upper face 2.

The punch 16 is then driven in a vertical movement from top to bottom, so as to come to attack the surface 2 of the profile 1 and carry out therein the roughing of the opening 10.

To this end, and as illustrated in FIG. 3b, the punch 16 crosses the upper surface 2, and causes therein the abovementioned opening blank, the downward movement of the punch advantageously being effected by sliding the end edges thereof between two lateral guides, respectively 37 and 38, carried by the fixed support 22 ..

In particular, because the distance which separates the vertical sails 4 and 5 bracing the faces 2 and 3 is equal, apart from the thickness of these sails, to that which delimits the short sides 14 and 15 of the opening, these sails are used to play the role of matrix with respect to the underside of the punch 16, the longitudinal edges 29 and 31 of this punch, cooperating with the webs 4 and 5 respectively in the manner of the two blades of a chisel, producing a perfectly precise and clean longitudinal cut along the entire length of the punch, on each side of it.

On the other hand, due to the fact that the webs 4 and 5 do not directly support the part of the sheet located between them, it is conceivable that the insertion of the punch through the surface 2, in line with the ends of this punch, will create in this sheet metal, in the vicinity but in front of the short sides of the fractions or portions of metal where the sheet metal will be forced towards the inside of the housing 9 and partially bent in it as illustrated in 39 and 40, in Figures 2b and 4 in particular.

The roughing of the opening 10 thus produced must then be completed in order to remove these metal fractions 39 and 40, while also giving the opening 10 its final longitudinal dimensions along the sides 12 and 13, at the same time as form the short sides 14 and 15, these must be perfectly straight and perfectly arranged in the plane of the surface 2. Figure 3c illustrates the position of the punch 16 at the end of the descent stroke of the piston 17, after the chip 36 has fallen produced inside the housing 9 in the profile 1. The movement of the punch 16 is shown diagrammatically in these Figures by the arrow 41.

In the next step, illustrated in Figure 3d, the piston 17 maintains the punch 16 inside the housing 9 in the profile 1, the latter being subjected to a lateral displacement force, in the example illustrated towards the left of the drawing as shown by arrow 42.

In this case, the sheet metal fraction 40 situated to the right of the opening blank 10 obtained previously, moves relatively relative to the punch 16, until it comes to abut against the corresponding side 43 of the piston 17.

At this instant, the piston 17 and the punch 16 are driven in a return movement from the bottom up, represented in FIG. 3e by the arrow 44, this movement allowing the inclined upper edge 34 of the punch to come to section frankly the sheet metal fraction 40, the lower end of the guide 38 serving as a support matrix for the surface 2, allowing a frank cut of the sheet metal, in a position which corresponds very precisely to the short sides 15 of the opening 10 to be made.

In the next phase, shown diagrammatically in FIG. 3f, after having reintroduced the punch 16 into the housing 7, the profile 1 is again moved laterally but this time to the right in the direction of the arrow 45, so as to bring the fraction opposite 39 against the lateral side 46 of the piston, the rise of the latter allowing, as before, the sectioning of this fraction 39 and the production of the short side 14, thereby completing the desired opening 10.

In the case where the section 1 is designed to have two openings, respectively 10 and 11, placed strictly opposite one another in the opposite faces 2 and 3, it suffices to turn the section 180 ° on itself- even and to introduce it again into the open groove 23 of the fixed support 22, the movable stop 24 then projecting inside the housing 9 through the opening 10 under the effect of its spring 27.

The stop 24 thus constitutes an anchor point for the profile 1, making it possible to position it exactly opposite the punch. The latter can then carry out the second opening 11, as illustrated in FIGS. 3g, 3h and 3i, which respectively take up the arrangements already described with regard to the formation of the first opening 10, in relation to FIGS. 3b, 3rd and 3f.

FIG. 5 shows on a larger scale the fraction of sheet metal 39 sectioned on the left side of the openings 10 and 11 by the return movement of the punch 16.

The tool considered thus makes it possible to carry out all the operations necessary on a single punching station, with a final cut with regular edges, the initial chip and the complementary fractions of sheet metal, eliminated respectively on the descent then on the ascent of the punch, being able to be easily evacuated, either due to their narrowing in width, or their withdrawal towards the outside of the profile.

Of course, it goes without saying that the invention is not limited to the embodiment more specifically described and shown.

Claims (7)

1. Punching tool for producing, in a tubular metal profiled section (1) of great length with a section closed on itself and exhibiting two opposite parallel faces (2, 3) located horizontally, one and preferably two identical rectangular openings (10, 11), respectively in one and the other of these faces, substantially in the middle of the length of the profiled section, the long sides (12, 13) of these openings extending in the longitudinal direction of the profiled section, which profiled section internally includes at least two parallel webs (4, 5) perpendicular to the opposed faces and parallel to the long sides of the openings whose short sides (14, 15) are substantially equal to the distance which separates these webs, which tool includes a punch (16) of parallelepipedal overall shape, the lower longitudinal cutting edges (29, 31) of which are parallel to the long sides of the openings, the width of the punch (16) being equal to that of the short sides while its length is less than that of the long sides, the punch (16) being secured to an operating piston (17) which can move inside a stationary support (22) exhibiting an open lateral groove (23) for positioning the profiled section under the punch (16) in line with an opening to be produced by the punch pressing vertically downwards into the profiled section through the face to be cut under the effect of the travel of the piston (17), the latter including a lengthwise dimension less than that of the punch (16), which comprises upper transverse edges (34, 35) which are also cutting edges for forming the short sides of the opening in succession following longitudinal travels of the profiled section in the groove (23) until it abuts against the piston (17) prior to the return movement of the latter, returning the punch (16) to the outside of the profiled section.
2. Punching tool according to Claim 1, characterized in that the cross-section of the punch (16) exhibits, along its short sides, a profile made up of two contiguous substantially inwardly circular arc-shaped regions (32), these regions being symmetrical with each other with respect to the vertical mid-plane of the punch and meeting at a ridge in this plane, in order to form a longitudinal central edge (33) situated in this plane beneath the common level of the two lower lateral edges (30, 31) of the punch.
3. Punching tool according to one of Claims 1 and 2, characterized in that the upper transverse edges (34) of the punch (16) are inclined to the horizontal plane, so as to section the metal sheet from one end to the other of the short sides (14, 15) of the opening during the return movement of the punch.
4. Punching tool according to any one of Claims 1 to 3, characterized in that the stationary support (22) includes two vertical lateral guides (37, 38) separated from one another by the length of the punch (16) along its long sides, against which guides the short sides of this punch slide during its falling and return movements, these guides forming supporting dies when the fractions of sheet metal facing it are cut out on the reascent of the punch.
5. Punching tool according to any one of Claims 1 to 4, characterized in that the difference in length between the punch (16) and the piston (17) is equal to the travel of the profiled section (1) in the open groove (23) of the support (22) prior to the reascent movement of the punch.
6. Punching tool according to any one of Claims 1 to 5, characterized in that the stationary support (22) comprises, in its open groove (23) taking the profiled section (1), a movable stop piece (24) which can move out of the way when the profiled section is engaged in this groove, it being possible, in contrast, for this stop piece to penetrate a first opening (10) made in one face of the profiled section after the latter has been turned through 180° on itself and one of its horizontal faces (2, 3) has been substituted for the other so as to allow the position of the profiled section to be indexed relative to the first opening (10) and a second opening (11) to be made in the opposite face, situated exactly opposite the first one.
7. Method for employing a punching tool according to any one of Claims 1 to 6, characterized in that it consists in placing the profiled section in the open groove of the stationary support so that it offers one of its horizontal faces opposite the punch in the raised position, in causing the punch to fall vertically downwards to form the rough cut of the opening in this face, with its long sides parallel to the parallel webs of the profiled section, in laterally shifting the profiled section towards the right or towards the left in a first direction so that the corresponding lateral side of the rough cut of the opening is applied against the piston above the punch, in causing the upward travel of the punch in order to finish cutting the short side of the opening, in again causing a downward travel of the punch, in shifting the profiled section laterally in the opposite direction from the first direction and in again causing the punch to travel upwards to finish off the opening along its opposite short side.

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