METHOD AND DEVICE FOR PRODUCING A HALF-SHELL PART

Abstract

The invention relates to a method for producing a half-shell part with a drawing punch and a drawing die. The object of providing a method for the process-reliable and cost-effective production of highly dimensionally stable half-shell parts is achieved in that, in a single work step, the drawing punch is advanced into the drawing die, a sheet metal blank is preformed into a sheet metal raw part with at least one base section, at least one frame section and optionally a flange section, wherein during the preforming with the drawing punch a material excess is introduced either into the base section and the frame section or into the optional flange section of the sheet metal raw part, and the sheet metal raw part is finished to form a half-shell part and calibrated.

Claims

1. Method for producing a half-shell part with a drawing punch and a drawing die, wherein a single work step the drawing punch is advanced into the drawing die, a sheet metal blank is preformed into a sheet metal raw part with at least one base section, at least one frame section and optionally a flange section, wherein the drawing punch comprises at least one base punch displaceably arranged relative to the drawing punch facing towards the drawing die, during the preforming with the drawing punch a material excess is introduced first into the base section or the frame section by moving the base punch towards the drawing die, and the sheet metal raw part is finished to form a half-shell part and is calibrated, wherein the sheet metal raw part is trimmed in the single work step.

2. Method according to claim 1, wherein the sheet metal raw part is finished by advancing the base punch into the base punch receiver as soon as the base punch has come to rest on the sheet metal raw part abutting the drawing die, and is calibrated.

3. Method according to claim 1, wherein the cutting edge is, at the same time as the placement of the base punch on the sheet metal raw part abutting against the drawing die, brought into contact with the sheet metal raw part.

4. Method according to claim 1, wherein during the finishing and calibration the material excess is forced from the base section of the sheet metal raw part into the frame section of the sheet metal raw part.

5. Method according to claim 1, wherein the sheet metal raw part is compressed using a compression surface at least in a frame section.

6. Method according to claim 1, wherein the sheet metal blank is held at least at the start of the performing with a holddown device.

7. Method according to claim 1, wherein a flange-free halfshell part or a flanged half-shell part is produced from the sheet metal raw part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention is now described in more detail and illustrated with the aid of drawings showing exemplary embodiments. In the drawings:

[0037] FIGS. 1a-c show a first exemplary embodiment of a device according to the invention in various states, in cross-section;

[0038] FIG. 2 shows a perspective view of an exemplary embodiment of a half-shell part that can be produced with the devices illustrated in FIG. 1;

[0039] FIG. 3a shows the cutting edge of the half-shell part illustrated in FIG. 2 in cross-section, compared to the cutting edge of a half-shell part from the prior art illustrated in FIG. 3b;

[0040] FIGS. 4a-e show a section of a second exemplary embodiment of a device according to the invention in various states, in cross-section;

[0041] FIGS. 5a-c show a third exemplary embodiment of a device according to the invention in various states, in cross-section;

[0042] FIG. 6 shows an exemplary embodiment of a half-shell part that can be produced with a device illustrated in FIG. 5, in a perspective view;

[0043] FIGS. 7a-c show a fourth exemplary embodiment of a device according to the invention in various states, in cross-section, and

[0044] FIG. 8 shows an exemplary embodiment of a half-shell part that can be produced with the device illustrated in FIG. 7, in a perspective view.

DETAILED DESCRIPTION OF THE INVENTION

[0045] The device illustrated in FIG. 1 comprises a drawing punch 1, which can be advanced by means (not shown) into the drawing die 2, whereby it can be brought into the positions illustrated respectively in FIGS. 1a-1c so as to produce from a sheet metal blank 17 first of all a sheet metal raw part 5 and then a half-shell part 3 from the said sheet metal raw part 5.

[0046] The drawing punch 1 has means for introducing a material excess into a base section 4 of the sheet metal raw part 5. It has a shape that can be changed by a base punch 6, which is displaceably arranged in a base punch receiver 7. The edges 8 and 9 of the base punch 6 facing towards the drawing die 2 are rounded off, so that the danger of formation of kinks in the base section 4 of the sheet metal raw part 5 can be reduced.

[0047] A cutting edge 10 and a compression surface 11 directly adjoining the latter are also formed on the drawing punch 1. The compression surface 11 is in this connection aligned substantially perpendicular to the deep drawing direction, i.e. to the advancing direction of the drawing punch 1 into the drawing die 2.

[0048] The drawing die 2 has a clearance 12 with an in-flow rounded portion 13, which transforms stepwise into the drawing die frame section 16 forming the frame section 15 of the half-shell part 3 to be produced, a counter-cutting edge 14 thereby being formed. The clearance 12 is at the same time sufficiently wide and deep so that in the deep drawing the sheet metal blank 17 is not obstructed by the counter-cutting edge 14.

[0049] First of all a sheet metal blank 17 is arranged between the drawing punch 1 and the drawing die 2, corresponding to the state illustrated in FIG. 1a. The sheet metal blank 17 of thickness P is at the same time held on the drawing die 2 with a hold-down device 18. The base punch 6 is located in a position projecting in the direction of the drawing die 2 and has contact with the sheet metal blank 17.

[0050] By means of the advancing means (not shown), which may be mechanical, pneumatic or hydraulic, the drawing punch 1 and drawing die 2 are now brought into the position illustrated in FIG. 1b. The sheet metal blank 17 is thereby preformed into a sheet metal raw part 5 with a frame section 15 and a base section 4. By means of a locking device (not shown here) the base punch 6 is locked in the aforementioned position. It is, however, also conceivable to hold the base punch 6 in the projecting position for example by means of a hydraulic or pneumatic cylinder, or also by means of a spring, during the preforming.

[0051] The sheet metal blank 17 is held on the drawing die 2 by the hold-down device 18 so that on the one hand material can be drawn underneath, but on the other hand an arching of the sheet metal blank 17 and the formation of folds associated therewith is avoided.

[0052] By means of the projecting base punch 6 a sagging to the desired geometry of the base is achieved, i.e. a material excess is introduced into the base section 4 of the sheet metal raw part 5. In the region of the in-flow rounded portion 13 the sheet metal raw part 5 abuts against the clearance 12. The base punch 6 settles in the position illustrated in FIG. 1b on the sheet metal raw part 5 abutting the drawing die 2. At the same time the cutting edge 10 of the drawing punch 1 comes into contact with the sheet metal raw part 5.

[0053] In this position the locking device of the base punch 6 is now released, so that the base punch 6 is displaced into the base punch receiver 7 as the drawing punch 1 advances further into the drawing die 2. In the case of a base punch held in the projecting position with a hydraulic or pneumatic cylinder or a spring, it is sufficient that the advancing means overcome the forces exerted by cylinders or springs.

[0054] As the drawing punch 1 and drawing die 2 approach closer to an accurately defined point, local stresses are produced in the sheet metal raw part 5 by the cutting edge 10, so that a crack is formed and a trimming of the sheet metal raw part takes place. The scrap 19, i.e. the unused material of the sheet metal blank 17, is at the same time displaced into the clearance 12 of the drawing die 2.

[0055] As indicated by the arrow, at the same time the material excess produced in the preforming is forced from the base section 4 and from the frame section 15 into the whole sheet metal raw part 5. The stresses in the frame section 15 due to the deep drawing of the sheet metal blank 17 are thus purposefully aligned. The elastic recovery of a half-shell part produced with this device is therefore in any case only slight and the dimensional stability of the half-shell part is improved.

[0056] In the position illustrated in FIG. 1c the drawing punch 1 is advanced completely into the drawing die, and is in the lower dead point. The drawing punch 1 and the drawing die 2, thus, basically form a negative image of the internal and external contour of the half-shell part to be produced.

[0057] The cutting edge 10 of the drawing punch 1 is in this connection arranged in the deep drawing direction spaced from the counter-cutting edge 14 associated with the drawing die 2. In this way the frame section 15 can be compressed in the course of the finishing and calibration. This also contributes to the high dimensional stability of the finished flange-free half-shell part 3 illustrated in FIG. 2, which is characterised in particular by a relatively smooth cut surface 20.

[0058] With regard to the wall thickness W of the half-shell part 3 according to the invention, the smooth cut proportion of the cut surface 20, as diagrammatically illustrated in FIG. 3a, is more than one third compared to a half-shell part from the prior art (FIG. 3b). Consequently, the illustrated half-shell part 3 can be welded in a particularly simple manner to further structural elements, in particular also to a half-shell part produced with a comparable device, in the I-joint so as to form a closed hollow shell profile.

[0059] FIG. 4 shows a section of an alternative embodiment of a device for producing a flange-free half-shell part 3′. This likewise comprises a drawing punch 1′ with a base punch 6′ and a drawing die 2′. The clearance 12′ is however not stepped, but transforms with an inclined surface 21′ into the drawing die frame section 16′.

[0060] The inclined surface 21′ has compared to the stepped transition the advantage that a counter-cut edge 14′ with a more obtuse angle is formed. Its wear can thereby be reduced. Furthermore, it can be manufactured more simply. On the other hand a stepped transition offers less resistance to displaced scrap during the trimming and reduces the danger of a blockage of the scrap in the device. Moreover, the inclined surface 21′ produces a self-centering of the cut edge 10′ during the trimming.

[0061] As in the device illustrated in FIG. 1, the cut edge 10′ in the position of the drawing punch 1′ advanced completely into the drawing die 2′ is, moreover, located deeper in the drawing direction than the counter-cut edge 14′ (see FIG. 4e). Consequently, in the device illustrated in FIG. 4 the whole cross-section of the half-shell part 3′ is compressed and converted into a plastic state.

[0062] A clearance that has an inclined surface, as well as a stepped clearance, can be combined with an arrangement of the cutting edge and the counter-cutting edge, in which the cutting edge and counter-cutting edge in the position of the drawing punch fully advanced into the drawing die, are at least at the same height.

[0063] With regard to the sequence of the forming procedure from the sheet metal blank 17′ via a sheet metal raw part 5′ to a half-shell part 3′, reference is made to the explanations given regarding FIG. 1.

[0064] Finally, FIG. 5 shows an embodiment of a device according to the invention with which a flanged half-shell part 3″ can be produced. Corresponding to the devices described hereinbefore, the device illustrated in FIG. 5 likewise comprises a drawing punch 1″ with a base punch 6″, which additionally includes a flange-forming punch 33″.

[0065] The drawing die 2″ comprises a drawing die base section 22″ forming the base section 4″ of the sheet metal raw part 5″, a drawing die frame section 16″ forming the frame section 14″ of the sheet metal raw part 5″, and a drawing die flange section 24″ forming the flange section 23″ of the sheet metal raw part 5″. The transition 25″ from the drawing die flange section 24″ to the drawing die frame section 16″ comprises in this connection an in-flow rounded portion and a drawing radius.

[0066] In a corresponding manner the base punch 6″ comprises a base section 26″ and a base punch frame section 27″, and the flange-forming punch 33″ comprises a flange-forming punch section 28″ with a cutting edge 10″. An inclined surface 21″, shown enlarged, is associated with this cutting edge 10″ on the side of the drawing die 2″, and allows the self-centering of the cutting edge 10″.

[0067] To produce the flanged half-shell part 3″, the sheet metal blank 17″ is first of all arranged between the drawing punch 1″ and the drawing die 2″, as shown in FIG. 5a. The base punch 6″ of the drawing punch 1″ is then in a position projecting in the direction of the drawing die 2″. The sheet metal blank 17″ is held on the drawing die 2″ by a hold-down device 18″ outside the drawing die flange section 24″. The counter-holding section 30″ of the drawing die 2″, held against the sheet metal blank 17″ by the hold-down device 18″, is at the same time spaced further from the drawing die base section 22″ compared to the drawing die flange section 24″.

[0068] By advancing the drawing punch 1″ into the drawing die 2″ a sheet metal raw part 5″ is first of all formed, a material excess being produced in the flange section 23″ of the sheet metal raw part 5″ (see FIG. 5b). The flange section 23″ of the sheet metal raw part 5″ experiences, due to the displaced planes of the drawing punch flange section 24″ and counter-holding section 30″, a convex bending as well as a concave bending when the sheet metal blank is drawn.

[0069] At the same time as the placement of the base punch 6″ on the sheet metal raw part 5″ abutting against the drawing die base section 22″, the cutting edge 10″ comes into contact with the sheet metal raw part 5″.

[0070] After the placement of the base punch 6″ on the sheet metal raw part 5″, only the flange forming punch 33′ still moves in the direction of the drawing die 2″, and the sheet metal raw part 5″ is trimmed with the cutting edge 10″ to form a flanged half-shell part 3″, and finished and calibrated.

[0071] In the position in which the drawing punch 1″ has advanced fully into the drawing die 2″ as illustrated in FIG. 5c, it can be seen that the flange-forming punch section 28″ is formed as an offset contour of the drawing punch flange section 24″. The offset has the thickness P″ of the sheet metal blank 17″, so that it is compressed by the excess material of the flange section 23″. The offset between the drawing punch base section 26″ and the drawing die base section 22″ corresponds to the thickness P″ of the sheet metal blank 17″. Between the drawing die frame section 16″ and the drawing punch frame section 27″ the offset is increased by a drawing gap, not shown in FIGS. 5a-c, so as to allow a material flow between the different sections of the sheet metal raw part 5″ during the finishing and calibration.

[0072] A highly dimensionally stable, trimmed half-shell part 3″ can thus for example be produced with the device, and is shown in a perspective view in FIG. 6.

[0073] FIG. 7 shows a further variant of an embodiment of a device according to the invention, with which a further shape of a flange-free half-shell part 3′″ can be produced, as shown in a perspective view in FIG. 8.

[0074] The only difference compared to the device illustrated in FIGS. 5a-c is that the flange-forming punch 33′″ has on the side a recess with a cutting edge 10′″, so that after the trimming of the sheet metal raw part 5′″ and due to the further advance of the device, the end section of the sheet metal raw part 5′″ is converted into the recess. The flange-free half-shell part 3′″ is finished and calibrated.

[0075] The high dimensional stability of the flange-free or flanged half-shell parts 3, 3′, 3″, 3′″ is promoted by the fact that, due to the compression, the whole cross-section is converted into a plastic state and stresses can thereby be aligned in a targeted manner.

[0076] All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0077] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0078] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.