EP0131770A1 - Method of fine-cutting work pieces, and fine-cutting tool for carrying out the method - Google Patents

Abstract

It shows how, when fine-cutting workpieces, they can be made conical or wedge-shaped, at least in some areas of their outer cut surfaces. A first possibility is to press the workpiece into a recess of the cutting plate (10) that tapers or narrows at least on partial circumferential areas during the cutting. Another possibility is to cut the workpiece from the material (17) in the manner of a penetration in a first working step and to complete the cutting process in a second working step and to press the workpiece into a recess of an embossing plate that tapers or conically narrows at least on partial circumferential areas . In both methods, the cut-out and at least partially circumferentially tapered or conical workpiece is removed from the cutting or embossing plate (10) by means of the ejector (12) when the cutting sticks (16) buy back.

Description

The invention relates to a method for fine cutting workpieces, the material being clamped between a guide plate (press plate) and a cutting plate, and the workpiece being cut out by means of a cutting punch and an ejector acting against it and guided in a recess in the cutting plate, and optionally additionally processed by means of an internal forming punch becomes.

Fine blanking (sometimes also called "fine blanking") differs from conventional punching technology essentially in that the workpiece is firmly clamped before and during the cutting process and guided with tight tolerances. For this purpose, the material - usually steel strip with a thickness of 0.3 mm to about 15 mm - is clamped in the tool between a guide or press plate and a cutting plate. The guide plate and / or the cutting plate carry an annular tooth adapted to the workpiece outline, which is pressed into the material. The ring spike prevents the material from flowing away to the side. The cutting process is carried out by means of a cutting punch guided in the guide plate with a tight tolerance and an ejector also closely tolerated in the cutting plate, which acts with a counterforce of approximately 10 to 20% of the cutting force against the Cutting punch presses so that the two punches guide the material and later the workpiece between them from the start of the cutting. Within the cutting punch and the ejector, several inner shaping punches and thus ejectors corresponding in opposite directions can be used for the purpose of internal shaping or perforation of the workpiece. An overview of the fineblanking technology is given in the publication VDI 3345 "Feinschneid", May 1980, of the "VDI guidelines". For the general state of the art, reference is made to this document.

Since, in the fineblanking technology, the cutting punches usually cannot dip into the recess of the cutting plate due to the narrow tolerances, a thin cutting burr remains on the circumferential edge of the workpiece facing the cutting punch, and the cutting punch and the ejector basically have essentially the same circumferential configuration as the guide openings are analog in the guide plate and in the cutting plate.

The present invention has for its object to provide a method for fine cutting workpieces according to the preamble of claim 1, which allows the manufacture of finely cut workpieces that are conical or wedge-shaped at least in parts of their outer cutting surfaces in a simple manner. Such a problem he is, for example, in the case of spur gears, the tooth flanks of which are not to be parallel, but rather with a certain inclination to one another. Another of many conceivable applications would be a gear wheel, the head and tooth space surfaces of which are to be arranged at a certain inclination relative to the axis of rotation.

A first method according to the invention, which achieves the underlying task, consists in that the workpiece is pressed into a recess of the cutting plate that tapers or tapers at least on partial circumferential areas during the cutting out. In other words, this means that the actual cutting process is overlaid in time and place by an embossing process that takes place within the recess of the cutting plate. During the cutting process, the proportion of material that is brought into flow and cut and corresponds to the workpiece not only experiences an axial feed in the resulting direction of movement of the cutting punch, but also, at the same time, an at least partial compression towards the cutting punch axis in accordance with the inclination or conicity.

According to the invention, a fineblanking tool for practicing this method consists in that the inner surface of the workpiece contour of the cutting plate, forming flat surfaces, at least on parts of its circumference and on a section in the axial direction of the ejector, starting in the support plane of the material, is arranged inclined to the ejector axis.

Deviating from the previously used fineblanking tools, the inner surface surface lines of the workpiece contour in the cutting plate are not completely parallel to the ejector axis, but rather are inclined at a distance corresponding to the workpiece thickness from the support plane of the workpiece away according to the desired conicity or the desired inclination of the workpiece inclined surfaces. The end section of the cutting plate facing the material or workpiece thus forms a circumferential embossing shape with inward-facing embossing surfaces located in this section. Accordingly, according to a further feature of the invention, the section measured in the axial direction of the ejector and having the embossing surfaces is slightly larger than the material thickness of the material, because because of the tapering of the cross section of the embossing recess in the cutting plate, the material displaced here must flow in the direction of the ejector axis.

The particular advantage of the described method for producing a workpiece with an at least partially conical or inclined edge surface is that it does not require any further work steps, in particular also no machining. The device required to carry out the method is also simpler Configuration and hardly more complex than a conventional fineblanking tool that can only cut.

Now there can be particularly problematic workpieces, for example those in which essentially thin-walled and small cross-sectional rings have to be cut, which are not inherently stable in themselves and in which the single-stage "combined cutting / embossing process" could therefore lead to complications. For these cases, the invention proposes a two-stage process, which is characterized in that in a first step the workpiece is (only) cut in the manner of an enforcement from the material and in a second step the cutting process is completed and the workpiece is pressed into a tapered or conically narrowing recess of an embossing plate, at least on partial circumferential areas.

The two work steps can of course and should be carried out expediently in one machine, in a subsequent tool. The first step is practically no different from a fineblanking process for producing a so-called "enforcement" (see VDI guidelines, p. 7, "3.6. Forming processes", example 6 vo). The difference is essentially only that the "asserted material" in the process according to the invention essentially already finished in the outer outline Workpiece corresponds. This is then embossed in the second work step in a second tool step on the outer cut surfaces and at the same time finished cut.

A fineblanking tool for carrying out this two-stage process is characterized in accordance with claim 4, characterized in that the tool of the first working stage is designed in a manner known per se to form an enforcement and that an embossing plate is arranged in the tool of the second working stage, in which the inner surface of the workpiece contour, Forming embossing surfaces is arranged at least on parts of their circumference and on a section in the axial direction of the ejector, starting in the plane of the embossing plate and inclined to the ejector axis.

Here too, as in the case of the aforementioned tool, the section having the embossing surfaces measured in the axial direction of the ejector is at least slightly larger than the material thickness of the material.

In principle, the tool of the second working stage does not differ from the individual tool performing the first method. Here only the cutting plate is essentially converted into an embossing plate.

• Fig. 1 ein "einstufiges" Feinschneidwerkzeug zur Ausübung des einstufigen Verfahrens,
• Fig. 2 eine Ansicht eines damit erzeugten Werkstücks,
• Fig. 3 und 5 die beiden Arbeitsstufen eines "zweistufigen" Werkzeugs zur Ausübung des zweistufigen Herstellungsverfahrens,
• Fig. 4 und 6 das jeweils nach Beendigung der Verfahrensschritte gemäß den Fig. 3 und 5 erhaltene Erzeugnis,
• Fig. 7 eine Aufsicht auf einen außenverzahnten Ring als beispielshaftes Werkstück und
• Fig. 8 eine Aufsicht auf einen Zahnausschnitt des Werkstücks nach Fig. 7.

The invention is understood from the following description of the two methods and tools, as shown in the schematic drawing are shown. Another drawing shows an example of a workpiece obtained with the method and the tools. The drawings show:

• 1 is a "one-step" fineblanking tool for performing the one-step process,
• 2 is a view of a workpiece produced with it,
• 3 and 5, the two working stages of a "two-stage" tool for practicing the two-stage manufacturing process,
• 4 and 6, the product obtained after completion of the process steps according to FIGS. 3 and 5,
• Fig. 7 is a plan view of an externally toothed ring as an exemplary workpiece and
• 8 is a plan view of a tooth cutout of the workpiece according to FIG. 7.

The tool according to FIG. 1 comprises - in an initially conventional design - a cutting plate 10 with a workpiece contour 11, in which a correspondingly contoured ejector 12 is arranged displaceably in the direction of its longitudinal axis 13. Above this half of the tool is a guide or press plate 14 with a contoured recess 15 for the correspondingly contoured Cutting punch 16, which is arranged coaxially to the ejector 12. Just for the sake of completeness, it should be mentioned that for workpieces that have additional internal shapes, at least one internal molded punch must be arranged within the ejector 12 and, accordingly, at least one ejector must be arranged within the cutting punch 16, for example of the type described under "2.1. Working principle" on page 2 VDI guidelines 3345.

On the side facing the material 17 (sheet metal strip), the guide or press plate 14 has an annular spike 18 which is wedge-shaped in cross section and penetrates the material 17 and prevents it from flowing out.

The workpiece contour 11 in the cutting plate 10 now has the special feature according to the invention that, starting from the material plane 19, it extends over a section 20, measured in the direction of the axis 13, which is slightly larger than the material thickness 21, on its inwardly facing peripheral surface 22 is at least partially inclined or conical, such that - as can clearly be seen in FIG. 1 - the cross section of the recess 11 towards the ejector 12 decreases at the corresponding points. Die 16 and ejector 12 therefore have different cross sections Q, q and diameter. In the example shown, the inclination 23 can be approximately 3 ° to 4 °, but also more. The corresponding angle of inclination is indicated at 24.

If, as an example, it is assumed that the circumferential surface 22 is circumferentially formed in the workpiece contour 11 over the section 20, the workpiece 25 shown in FIG. 2 results in the form of a truncated cone with an evenly conical outer cutting surface 26 all around.

In the method which is carried out with the tool according to FIG. 1, at the same time the cutting punch 16 advances, the material 27 which is made to flow is pushed downward against the counterforce of the ejector 12 with respect to FIG. 1 and thus simultaneously into that of the peripheral surface 22 limited "embossing shape" pressed within the cutting plate 10. Fig. 1 shows the final cutting state, in the connection of which the tool halves open again.

The tool parts are actuated in the manner and sequence customary for fineblanking in that the cutting plate 10 and the guide plate 14 are first moved against one another until the material is not deformed until they grip the material between them. Then, initially also in opposite directions, the cutting punch 16 and the ejector 12 run towards one another until they clamp the material 17 between them. The cutting punch 16 then moves downward with respect to FIG. 2, while the ejector 12 follows this movement while exerting a counter pressure until the situation shown in FIG. 1 is reached.

3 shows the first stage of a two-stage tool for carrying out the two-stage method. This tool is made up of a cutting plate 110, an ejector 112, a guide or pressing plate 114 with ring serration 118 and a cutting punch 116 guided in the guide plate 114. This tool and its function correspond to a conventional fineblanking tool with which enforcements are generated. The "enforced" blank is identified by 127 and is shown separately once again adhering to the material 117 in FIG. 4. The pre-cut blank 127 is still connected to the material 117 via a relatively strong material bridge 128. 4, the material 117 with the partially cut blank 127 is fed to the second tool stage shown in FIG. 5. The individual parts of this tool level are each provided with reference numbers increased by 100. One difference is that plate 210 is an "embossing plate". Analogously to the cutting plate designated by 10 in FIG. 1, it has a section 220 with an at least partially conical or inclined embossing surface 222. Accordingly, the finished workpiece 225, like the workpiece 25 in FIG. 2, has the shape of a truncated cone with an all-round cone with an analogous geometry Outer cut surface 226. Also in the two-stage process, an embossing process takes place, this time starting from a precut or cut workpiece.

FIG. 7 schematically shows a typical workpiece, the methods and tools according to the invention are particularly suitable for producing. It is an annular spur gear 30, the teeth are designated 31. As shown in FIG. 8, the tooth flanks 32 and 33 are conical at an angle 35 with respect to the axis of rotation 34 of the toothed ring 30. The tooth bases 36 and the tooth heads 37, however, can have surfaces whose surface lines run parallel to the axis 34. This workpiece 30 thus shows a typical example of the fact that and how only parts of the outer cut surfaces of a finely cut workpiece can be produced in a simple manner conically or obliquely.

Claims (5)

1.Procedure for the fine cutting of workpieces, the material being clamped between a guide plate (press plate) and a cutting plate and the workpiece being cut out by means of a cutting punch and an ejector acting against it and guided in a recess in the cutting plate and, if appropriate, additionally being processed by means of an internal forming punch, characterized in that the workpiece is pressed into a recess of the cutting plate which tapers or conically narrows at least on partial circumferential areas during the cutting out. 2.Procedure for fine cutting workpieces, the material being clamped between a guide plate and a cutting plate and the workpiece being cut out by means of a cutting punch and an ejector acting against it and guided in a recess in the cutting plate, and optionally also being processed by means of an internal forming punch, characterized in that that in a first step the workpiece is cut from the material in the manner of an assertion and that in a second step the cutting process is completed and the workpiece is pressed into a recess of an embossing plate that tapers or tapers at least on partial circumferential areas. 3. Fineblanking tool for carrying out the method according to claim 1, characterized in that the inner surface (22) of the workpiece contour (11) of the cutting plate (10), forming embossing surfaces, at least on parts of its circumference and on a section (20) in the axial direction (13th ) of the ejector (12), starting in the support plane (19) of the material (17), is arranged inclined to the ejector axis (13). 4. Fineblanking tool for carrying out the method according to claim 2, characterized in that the tool of the first stage (Fig. 3) is designed in a manner known per se to form an enforcement (Fig. 4) and that in the tool of the second stage (Fig 5) an embossing plate (210) is arranged, in which the inner surface (222) of the workpiece contour (211), forming embossing surfaces, at least on parts of its circumference and on a section (220) in the axial direction (213) of the ejector (212), starting in the plane (219) of the embossing plate (210), arranged inclined to the ejector axis (213). 5. Fineblanking tool according to claim 3 or 4, characterized in that the measured in the axial direction (13; 213) of the ejector (12; 212), the embossing surfaces (22; 222) having section (20; 220) is slightly larger than the material thickness (21; 221) of the material (17; 217).

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