DD258192B1 - STRETCHING TOOL FOR MANUFACTURING MULTIPLE-WOVEN, PARTICULARLY UNREGULAR, SHEET MOLDING PARTS - Google Patents

Description

According to the invention, the object is achieved by providing the radiused inner edge of the die face

opposite holding surface circumferentially to the stamp coat a constant distance to the edge between

Stamp face and stamp coat has. In an embodiment of the invention, the distance between Stempelmantei and inner edge of the punch face

projected opposite holding surface in the stroke direction, formed in parallel.

After release of the press stroke, first the movable holding element moves towards the fixed holding element,

until the edge of the previously inserted board between the holding surfaces of the holding elements is firmly clamped. By the inventive design of the radiused inner edge opposite the die face

Holding surface depending on the stamp training the board is pre-bent during clamping so that almost all Elements of the end face of the now to be moved to the pre-bent board punch simultaneously on the sheet surface

incident.

By the refilling preventing solid clamping of the workpiece edge are the further movement of the punch

almost all workpiece elements within the holding surfaces are stretched simultaneously and thereby subjected to a relatively uniform elongation.

At the end of the Vorhubes the finished sheet metal part is produced as an image of the punch face with a frame training, the Tangent arrangement between the radii at the edge between the punch face and skirt and at the inner edge

the opposite of the punch face Haitefläche corresponds.

With the solution according to the invention a higher percentage degree of stretching and thus a better material utilization

achieved compared to the technical state. The sheet metal parts have greater stability and molding accuracy.

embodiments

The invention will be explained in more detail by two embodiments. The drawings show in

Fig. 1: a tool embodiment with arranged in the upper part stamp; perpendicular to the tool movement and in the

top dead center shown (front view),

2 shows a side view of the tool according to FIG. 1 at bottom dead center, FIG.

3 shows two phases of the tool position and workpiece formation according to FIG. 1, in each case in section, FIG. 4 shows a detail according to FIG. 3 B, FIG.

5 shows an illustration of special form elements on the holding surfaces of the holding elements, FIG. 6 shows a mold embodiment with stamp arranged on the lower part, after the deformation of the workpiece in FIG

top dead center and shown in section and in Fig. 7: a bottom view of the upper part of the tool according to Fig. β.

In a tool for stretch forming a multi-curved workpiece with approximately rectangular outer contour is

1 to 4 in the upper die 1 a not shown on the drawing ram of a double-acting press attached

Stamp 3 with the convex end face 4, which corresponds to the shape of the sheet metal part to be produced. That's not the same

illustrated blank holder ram of the press attached tool shell 1 carries the stamp 3 completely enclosing movable support member 7 with the located on the side of the stamp holding surface 11. The on the table of not shown

Press-mounted lower tool part 2 has the fixed holding element 8, which is that of the punch end face

has opposite holding surface 9 and the stamp 3 in the bottom dead center also completely encloses.

According to the invention, the radius 10 provided with the inner edge of the punch face 4 opposite Holding surface 9 to the edge between the punch face 4 and punch jacket 5, circumferentially considered to the latter, in the same Distance arranged. From this it can be deduced that the sections of the holding surface 9, the inner edge of which projected represents a straight line, each concave

are formed. Due to the congruence, the opposite portions of the holding surface 11 of the movable holding member 7 are convex.

In order to ensure a retention of the workpiece edge during the ironing process, so that no material from the Edge region nachfließt in the workpiece interior, the support surfaces 9 and 11 partially and opposite special Shaped elements 12 and 13, for example according to Figure 5 have. In order to prevent particularly large and / or very thin workpieces that the inserted board 18th

in the lower part of the tool is so bulged by its own mass that a holding of its edge is no longer possible, in the region of the greatest deflection against the punch face 4 resiliently arranged in the lower tool part 2

Holding members 14 are used in FIG. 1. After inserting the board 18 and triggering the press stroke moves first the blank holder ram the movable Retaining element 7 to the fixed support member 8 and the edge of the board 18 is fixed between the support surfaces 9 and 11

clamped.

Due to the inventive arrangement of the inner edge of the punch face 4 opposite Holding surface 9 - at the same distance from the edge between the punch face 4 and 5 stamp coat - have both Retaining surfaces 9 and 11 a special spatial training, which during clamping to the pre-bent board 19 as shown in FIG. ЗА

leads. As a result of this special pre-bend, almost all elements of the downwards movement of the drawing ram meet

Stamp face 4 at the same time on the workpiece surface. In the following with further downward movement of the punch forming the workpiece edge remains between the support surfaces. 9

and 11 firmly clamped to prevent Nachfließen the material, and it is formed by stretching the material within the holding surfaces 9 and 11, the sheet metal part 20, Fig. 3B.

So that the material can stretch unhindered within the holding surfaces 9 and 11, the determination is according to the invention

projecting in the stroke direction distance 17 between the punch jacket 5 and the inner edge of the

Stamp end face 4 opposite holding surface 9 required. Conveniently, one at the radius 6 of the Stamp 3 and the radius 10 at the inner edge of the support surface 9 fitting tangent 15 as shown in FIG. 4 at the end of Tool stroke (bottom dead center) form an angle 16 of 15 ... 75grd to the punch jacket 5. This location of the Tangente 15

approximately corresponds to the formation of the oblique frame of the sheet metal part 20th

By the explained training of the active tool elements and by a specific type of force attack on the

Pre-bent board 19 almost all surface elements of the workpiece are involved in the forming within the holding elements and there is a relatively uniform elongation of the material in said region, whereby strain peaks are avoided. The sheet-metal part 20 has a higher compared with stretch-formed parts produced by known tools

Stability, a better impression accuracy and a higher material utilization on. For use in a single-acting press with die cushion in the press table is the embodiment of FIG. 6th

intended. Here, the punch 3 is arranged in the lower tool part 2 and is actuated by the die cushion.

The stamp face 4 opposite holding surface 9 with a special arrangement of its inner edge is located at

This embodiment of the movable support member. 7

Fig. 7 shows a bottom view of the upper tool part 1 of this embodiment at the bottom dead center with in the amount of Holding surface 9 cut punch. The stamp face 4 opposite holding surface 9 encloses the Stamp 3 at a parallel distance 17 between its inner edge and the punch jacket. 5 Further details and the mode of action of this tool variant correspond to those of the illustrated tool according to

Fig. 1 to 5.

Claims (2)

1. stretch-forming tool for producing multiply curved, in particular irregular sheet metal parts whose stamp has a workpiece shape corresponding end face and a radius at the edge between face and mantle, arranged around the stamp holding elements against each other directed congruent holding surfaces for the edge of the workpiece, wherein the inner edge of the die face opposite the support surface is rounded by a radius and an adjacent thereto and the radius of the edge between the face and mantle of the punch tangent at the end of the tool stroke forms an acute angle, characterized in that the radius (10) provided with the inner Edge of the punch face (4) opposite retaining surface (19) around the punch jacket (5) circumferentially at a constant distance from the edge between the punch face (4) and punch jacket (5). 2. stretch-forming tool according to claim 1, characterized in that the distance (17) between the punch jacket (5) and inner edge of the die face (4) opposite holding surface (9), projected in the stroke direction, is formed in parallel. For this 8 pages drawings Field of application of the invention The invention relates to a tool for producing multiply curved, in particular irregular sheet metal parts, for. B. body parts, by ironing on pressing. Characteristic of the known state of the art In the relevant patent and technical literature, a variety of process and equipment variants for the production of single or multiple curved sheet metal parts is described by ironing. Tools with integrated holding elements for the edge of the sheet metal part have this predominantly in pairs opposite, d. h., quadrilateral boards are held on two opposite edges. The holding surfaces of the stationary and movable holding elements according to DD-WP117366 perpendicular to the tool stroke movement and flat. According to DE-OS 3204941 the retaining surfaces are also flat, but partially deviating from the perpendicularity formed to the tool stroke and the inner edge of the die face opposite the support surface is mainly provided with a radius. According to DD-WP 121280, the inner edge of the die face opposite planar and perpendicular to the lifting movement holding surface is changed by a transversely varying radius of curvature to a convexly curved surface in two directions. In order to achieve a secure retention of the workpiece edges during the ironing, these are before Streckziehvorgang also partly even transformed by the holding surfaces have corresponding form elements. So will according to SU-EB 1018752 introduced by means of a bead on the both sides of the movable holding elements in both festzuhaltenden workpiece edges a bead. In SU-EB 1175590 is prescribed to introduce at the four edges of a rectangular stretch-iron part two or three straight and parallel arranged beads. Finally, it is shown in JP-EB 59-218 225 that arranged around the punch movable support member has a bead on its support surface, the opposite holding surface of the fixed support member is formed congruent and that is deformed by the retaining elements of the workpiece edge flange. If now a method variant is used in the production of irregularly shaped and multiply curved sheet metal parts, in which no pregrouting, but the edges of the workpieces are only recorded before and during the Streckziehens, the stamp applies only with a small surface portion of its end face on the sheet surface , At these points, the material is subjected to particularly high stress, so that it can come to the end of the ironing process locally strong decreases in thickness and constrictions and cracks. Other portions of the tool undergo too little change in shape, resulting in the consequence to poor stability and dimensional accuracy of the formed part. Object of the invention The aim of the invention is multiply curved, flat sheet metal parts with respect to the known solutions improved quality, such. B. higher Abformgenauigkeit and greater stability. Explanation of the essence of the invention The invention has for its object to provide a stretch-forming tool for producing multi-curved, in particular irregular, sheet metal parts, which ensures that almost all lying within the holding elements surface portions are involved in the forming and thereby subject to a relatively uniform elongation. -ν-1 ^ i ΊΥ CN Ll. -ί- CO Ю CQO Я Op "2 го о CD СО 00 ll CM • 0- -25 ^ 1 92 Lf) • i І О I 92 οα> sr ^ cp go cn • ff H δ 1 9 О) ll