EP2604358B1 - Method for producing a cup-shaped sheet metal item - Google Patents

Abstract

The method involves sending two press mold halves (31,32) having a semi-annular projection along a first stroke axis of the peripheral wall, for shaping groove in first pressing step, so as to form a preform of the groove. Two press mold halves (41,42) having a semi-annular projection on the peripheral wall are sent along a second lifting axis in second press step relative to peripheral wall rotated around angle of rotation to the first lifting axis.

Description

The invention relates to a method for producing a cup-shaped sheet metal work piece with a hub, on which an annular peripheral wall protrudes, wherein on an outer side of the peripheral wall at least one groove is formed without cutting, according to the preamble of patent claim 1.

Cup-shaped sheet metal workpieces with grooves formed on the outside are well known, for example in the production of so-called poly-V pulleys. Such a method is for example in the EP 2 339 217 A1 described.

It is known to mold the outer grooves into a pot-shaped starting workpiece by means of so-called spinning rolls. The workpiece is set in rotation and delivered a correspondingly profiled spinning roller to the outside. For this method, a centric clamping of the workpiece on the spindle of the spinning machine is necessary, for which the component must have a certain minimum size. For set-up, clamping, start-up of the rotation and infeed of the spinning rollers, certain set-up times are required, so that this method is hardly economical for smaller components. Such methods go out of the DE 4 220 152 A1 or the EP 1 747 827 A1 out.

When manufacturing on presses, the problem is the formation of undercuts. In addition, pressing burrs and elastic deformations may form during pressing, so that the dimensional accuracy and rotational symmetry of the workpiece is impaired.

The invention has for its object to provide a method by which such sheet metal workpieces can be produced economically and with good dimensional accuracy, even with smaller component sizes.

The object is achieved according to the invention by a method having the features of claim 1. Preferred embodiments of the invention are specified in the dependent claims.

The inventive method is characterized in that for forming the groove in a first press step at least two press tool segments are each delivered with a partial annular projection in a first delivery to the peripheral wall of a cup-shaped intermediate form, wherein the peripheral wall (14) enclosed and formed a preform of the groove and that subsequently in a second press step, at least two press tool segments, each having a part-annular projection, are delivered to the peripheral wall in a second infeed which is twisted by an angle of twist relative to the peripheral wall for the first feed.

A basic idea of the invention is to produce such cup-shaped sheet metal workpieces in a forming press between press tool segments. Preferably, a center or rotation axis of the cup-shaped sheet metal workpiece is arranged transversely and in particular at right angles to the feed direction of the press tool segments. In the contracted state, the press tool segments enclose a space through which an outer contour of the cup-shaped sheet metal workpiece is defined. In this case, each press tool segment on a part-annular projection, which are pressed to form the annular groove in the peripheral wall of the sheet metal workpiece.

In order to avoid according to the invention the best possible dimensional accuracy of the workpiece while largely avoiding burrs on the tool joints and elastic recovery of the material, a second press step is performed. In this case, a relative rotation of the workpiece is carried out that engage in this second press step the press tool segments so offset from the first press step on the peripheral wall that forming burrs do not rest on the parting lines of the tool halves.

In this way, a degree of joint that may have been formed in the first pressing step is leveled again and a shaping of the sheet metal workpiece, in particular in the case of cylindrical or rotationally symmetrical shapes, is achieved by at least partially compensated elastic recovery deformed. The shape of the at least one groove is dimensionally and dimensionally accurate.

The inventive method can be carried out in a particularly efficient manner on a forming press, which can be driven with a processing cycle of up to less than 1 second. It can thus achieve a high output and thus a particularly economical production.

It is particularly preferred that for forming the groove in a first press step, two press tool halves are each provided with a semi-annular projection along a first stroke axis to the peripheral wall, wherein a preform of the groove is formed, and then in a second press step two press tool halves each a semi-annular projection are delivered to the peripheral wall along a second stroke axis, which is based on the peripheral wall rotated by a twist angle to the first stroke axis.

In principle, the relative rotation of the workpiece between the two press steps relative to the press tool segments can be only a few angular degrees. A particularly high dimensional accuracy can be achieved according to the invention in a preferred manner in that the angle of rotation is 90 ° or approximately 90 °. This applies in particular to two press tool halves.

The relative rotation can in principle be effected by the fact that the sheet metal workpiece is fixed and a press workpiece is twisted for this purpose. It is particularly efficient according to the invention that between the two press steps, the sheet metal workpiece is rotated, wherein the first delivery is carried out in a first press step rectified to the second delivery in the second press step. The delivery is directed radially to the center axis of the peripheral wall.

It can be provided according to an advantageous variant of the invention that the same press tool is used for the first press step and the second press step. In this case, only one press tool is needed.

For large-scale production, it is preferred according to the invention that the press tool segments for the first press step in a first press tool and the press tool segments for the second press step in FIG a second press tool are arranged, wherein the sheet metal workpiece is transported from the first press tool to the press tool. In this transport step between the two juxtaposed and rectified press tools rotation of the sheet metal workpiece can be done. If more than two press tool segments are used in a press tool, the lifting movement of the press via a translation, such as a wedge slide mechanism is divided in the desired direction of delivery.

A particularly economical production results according to the invention in that the two press tools are arranged in a transfer line of a press. A transfer line according to the invention is a concatenation of press tools in a press, wherein after each processing step, the workpiece in the transfer line is further promoted to a station. Thus, the inventive production of the cup-shaped sheet metal workpiece with at least one groove in the peripheral wall in a simple manner with other punching, bending, deep drawing or other forming steps can be combined, which are executable in a lifting press.

According to a preferred variant of the invention it is provided that a plurality of grooves are formed simultaneously. The grooves may have different groove cross-sectional shapes or preferably the same shapes. The workpiece may be cylindrical, rotationally symmetric or even angular or other polygonal shape.

Furthermore, it is preferred according to the invention that two press steps are provided for each individual form of the groove, wherein a second pressing step is carried out for the final forming of a first groove with a press tool, by which a preforming of a second groove takes place simultaneously. In a preforming of the first groove, this may preferably not yet be fully formed. Rather, a final molding to the final desired shape of the groove would be done only in the second or a further pressing step. By this stepwise molding a particularly high dimensional accuracy is achieved because the material in the workpiece more time is granted to flow.

According to the invention, it is particularly economical that the cup-shaped intermediate shape is shaped, in particular deep-drawn, from a sheet metal.

This can be done in particular by forming the intermediate mold from a sheet metal coil in a press in a transfer line and then finishing the cup-shaped sheet metal workpiece. Starting from the wound sheet metal strip, it is guided by the coil into the transfer line of a press. The sheet is cut to length and formed into the cup-shaped intermediate shape with a radially extending hub surface and a circumferential wall running in the axial direction. In this produced in particular by thermoforming peripheral wall then the molding of the groove or grooves can be carried out according to the invention. Furthermore, a hole pattern can be punched or imprints are made in the hub surface.

A preferred variant of the method according to the invention is that more than two tool press segments, in particular three or four, are delivered to the peripheral wall at an equal angular distance from each other. The tool press segments are usually arranged on a lifting press with a stroke direction. The delivery of the more than two tool press segments takes place radially to the peripheral wall or to the center axis of the workpiece. Thus, in four tool press segments, about two tool press segments formed as a quarter can be arranged on the upper lifting ram of the press and two tool press segments formed as a quarter on the lower press table. The respective radial feed movement of the individual tool press segments, which is rotated by 90 ° relative to one another, can be effected by a deflection mechanism, in particular a wedge-sliding mechanism. In this case, the feed paths of the individual tool press segments can be arranged approximately at 45 ° to a vertical stroke direction of the press. However, it can also be arranged 3, 5, 6 or more tool press segments, in which case the corresponding mechanism for implementing the lifting movement of the press must be adjusted accordingly in the respectively necessary radial feed movement.

In this case, the angular distance between the individual feed directions is preferably the same in each case, so that a symmetrical force distribution results around the workpiece.

It is preferred according to the invention that the angle of rotation corresponds to half the angular distance. The arrangement and number of tool press segments in a first and a second press tool are preferably the same, wherein the axial directions of the individual delivery directions of the tool press segments are rotated in the second press step with respect to the first press step by half the angular distance. In four tool press segments with an angular distance of 90 ° to each other thus results in a twist angle of 45 °. As a result, a particularly symmetrical deformation and a substantial avoidance of press joints is achieved.

Fig. 1

eine Querschnittsansicht durch ein erfindungsgemäß hergestelltes Blechwerkstück;

Fig. 2

eine Draufsicht auf das Blechwerkstück gemäß Fig. 1;

Fig. 3

eine perspektivische Ansicht auf ein Pressenwerkzeugsegment zur Herstellung eines Blechwerkstückes nach der Erfindung;

Fig. 4

eine schematische Darstellung eines Fertigungsablaufes nach dem erfindungsgemäßen Verfahren mit zwei Pressenwerkzeugsegmenten; und

Fig. 5

eine schematische Darstellung eines weiteren Fertigungsablaufs mit vier Pressenwerkzeugsegmenten.

The invention will be further elucidated on the basis of preferred exemplary embodiments, which are illustrated schematically in the attached drawings. In the drawings show:

Fig. 1

a cross-sectional view through a sheet metal workpiece produced according to the invention;

Fig. 2

a plan view of the sheet metal workpiece according to Fig. 1 ;

Fig. 3

a perspective view of a press tool segment for producing a sheet metal workpiece according to the invention;

Fig. 4

a schematic representation of a manufacturing process according to the inventive method with two press tool segments; and

Fig. 5

a schematic representation of another manufacturing process with four press tool segments.

An inventive cup-shaped sheet metal workpiece 10 is shown in an enlarged view in Fig. 1 shown. This sheet metal workpiece 10, which may have a diameter of about 4 cm and below, comprises a disc-shaped hub 12. Along the outer periphery of the hub 12, which has a pre-stamping, concentric with a central axis 11 extends a drum-shaped peripheral wall 14. In the outside of the Circumferential wall 14 are formed two annular grooves 16 without cutting.

As shown in the illustration Fig. 2 can be seen, the sheet metal workpiece 10 is cylindrical and rotationally symmetrical to the center axis 11 is formed. The representation of Fig. 1 is a cross section according to the section AA of Fig. 2 ,

Such sheet metal workpieces 10 with a relatively small diameter of a few cm are not or hardly economically by conventional rotary forming process, such as pressing method produced. According to the invention, a forming or lifting press with a press tool is used for producing such a sheet metal workpiece 10, of which a semi-sound-shaped first press tool segment 31 in Fig. 3 is shown.

The block-shaped first press tool segment 31 has in its center region a trough-shaped, semi-cylindrical mold recess 34, on which, corresponding to the grooves 16 to be formed, semi-annular projections 36 are formed. The trough-shaped mold recess 34 is bounded laterally by the abutment surfaces 38, at which corresponding abutment surfaces of the second opposing press tool half come to a stop.

In the closed state, the two press tool halves enclose the sheet metal workpiece 10 and thus give an outer contour of the cup-shaped sheet metal workpiece 10 with the formation of the grooves 16. In such a pressing operation, the joint between the two press tool halves is usually detected as a small but noticeable line-shaped Pressengrat on the sheet metal workpiece 10. Also, the axial lifting movement, which along guide pins, not shown, which engage in guide holes 39, due to a certain elastic resilience of the metallic sheet material lead to deviation from the rotational symmetry.

According to the invention, this is demonstrated by a process flow shown by way of example Fig. 4 largely avoided. According to this first variant of the method according to the invention, a first pressing step takes place on the sheet metal workpiece 10 in a first press tool 30, which has a first press tool segment 31 and a second press tool segment 32. The two half press tool segments 31, 32 are preferably identical or mirror-symmetrical. By closing the two press tool segments 31, 32 in a first stroke direction H1, an intermediate shape of the sheet metal workpiece 10 is formed. After opening the press tool 30, the sheet metal workpiece 10 is transported laterally to a second press tool 40. In this linear transport process, the sheet metal workpiece 10 is rotated, preferably by 90 °.

In this rotated position, the sheet metal workpiece 10 is inserted into the second press tool 40. Subsequently, the first press tool segment 41 and the second press tool segment 42 of the second press tool 40 are moved together in the stroke direction H2 and the second press tool 40 is closed. Here, the second pressing step is performed on the sheet workpiece 10. In this embodiment, the two lifting axes or lifting directions H1 and H2 are parallel and rectified.

Due to the rotation of the sheet metal workpiece 10 by 90 ° relative to the first press step so a formed Pressengrat be braced on the sheet metal workpiece 10 again. Due to the preforming in the first press step, virtually no further press ridge forms during the second press step. In addition, a certain out-of-roundness, which is formed during the linear forming movement in the first pressing step on the sheet metal workpiece 10, due to the rotation of the sheet metal workpiece 10 in the second pressing step is largely compensated.

According to the invention, grooves 16 on the outer circumference of a preferably rotationally symmetrical sheet metal workpiece 10 can thus be produced without cutting, even in the case of simple and relatively small workpieces, in an economically efficient manner.

A further embodiment of the invention according to Fig. 5 two upper die segments 31a, 31b and two lower die segments 32a, 32b. The tool press segments 31a, 31b are arranged on an upper lifting ram and the lower tool press segments 32a, 32b on a lower press table radially deliverable to the center axis 11 of the sheet metal workpiece 10. In the present case, the stroke direction of the press is indicated by the arrows P1, which may be vertical in particular. The four tool press segments 31a, 31b, 32a, 32b are arranged at an equal angular distance of 90 ° and with a bevel angle of 45 ° to the stroke direction P1. The individual tool press segments 31 a, 31 b, 32 a, 32 b are each formed as a quarter-circle segments for forming the cylindrical peripheral wall 14.

After the first pressing step, the sheet metal workpiece 10 is rotated by half the angular distance, ie by 45 °, so that a second press step can be repeated with this press tool arrangement. Due to the individual delivery directions Z1, Z4 of the individual tool press segments 31a to 32b becomes a special Roundness of the sheet metal workpiece 10 achieved while largely avoiding burrs.

Claims (13)

1. Method for producing a cup-shaped sheet metal workpiece (10) with a hub (12), from which an annular circumferential wall (14) projects, wherein at least one groove (16) is formed in a non-cutting manner on an exterior of the circumferential wall (14),
   characterized in that
   to form the groove (16) in a first pressing step at least two pressing tool segments (31, 32), each having a partially annular projection (36), are fed in a first feed motion to the circumferential wall (14) of a cup-shaped intermediate form, wherein the circumferential wall (14) is enclosed and a preform of the groove (16) is developed, and
   in that subsequently in a second pressing step at least two pressing tool segments (41, 42), each having a partially annular projection (36), are fed to the circumferential wall (14) in a second feed motion, which, in relation to the circumferential wall (14), is twisted about an angle of twist with respect to the first feed motion.
2. Method according to claim 1,
   characterized in that
   to form the groove (16) in the first pressing step two pressing tool segments (31, 32), each having a semi-annular projection (36), are fed along a first lifting axis to the circumferential wall (14), wherein the preform of the groove (16) is developed, and
   in that subsequently in the second pressing step two pressing tool segments (41, 42), each having a semi-annular projection (36), are fed to the circumferential wall (14) along a second lifting axis, which, in relation to the circumferential wall (14), is twisted about an angle of twist with respect to the first lifting axis.
3. Method according to claim 1 or 2,
   characterized in that
   the angle of twist amounts to 90° or approximately 90°.
4. Method according to any one of claims 1 to 3,
   characterized in that
   between the two pressing steps the sheet metal workpiece (10) is turned, wherein the first feed motion in the first pressing step is effected in the same direction with respect to the second feed motion in the second pressing step.
5. Method according to any one of claims 1 to 4,
   characterized in that
   for the first pressing step and the second pressing step the same pressing tool is employed.
6. Method according to any one of claims 1 to 4,
   characterized in that
   the pressing tool segments (31, 32) for the first pressing step are arranged in a first pressing tool (30) and the pressing tool segments (41, 42) for the second pressing step are arranged in a second pressing tool (40), wherein the sheet metal workpiece (10) is transported from the first pressing tool (30) to the second pressing tool (40).
7. Method according to claim 6,
   characterized in that
   the two pressing tools (30, 40) are arranged in a transfer line of a press.
8. Method according to any one of claims 1 to 7,
   characterized in that
   several grooves (16) are formed simultaneously.
9. Method according to claim 8,
   characterized in that
   for each individual form of the groove (16) two pressing steps are provided, wherein a second pressing step for finish-forming a first groove (16a) is carried out with the pressing tool (30, 40), through which a preforming of a second groove (16b) is effected simultaneously.
10. Method according to any one of claims 1 to 9,
    characterized in that
    the cup-shaped intermediate form is formed, in particular deep-drawn from a sheet metal.
11. Method according to claim 10,
    characterized in that
    based on a sheet metal coil, in a press in a transfer line the intermediate form is formed and the cup-shaped sheet metal workpiece (10) is finished.
12. Method according to any one of claims 1 and 3 to 11,
    characterized in that
    more than two pressing tool segments, in particular three or four, are fed at the same angular distance to each other to the circumferential wall (14).
13. Method according to claim 12,
    characterized in that
    the angle of twist corresponds to half the angular distance.

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