Tool and method for producing stamped parts

An upper die part includes an embossing bell, a stripper ring, and an inner shape embossing element. The stripper ring has an embossing surface with a corrugated profile on the embossing surface. A lower die part includes an embossing anvil having a corrugated profile on its embossing surface. The embossing bell and the inner shape embossing element each are provided with an embossing shoulder, which are disposed, with respect to the corrugated profile of the stripper ring, in the stroke direction in such a way that the shoulders can seize the burrs only alter the corrugating step. The corrugating step takes place prior to burr compression. The outer and inner contours of the disk are not able to change positions, but are able to change shapes on the burr side after the corrugating step.

BACKGROUND OF THE INVENTION

The invention relates to a method and tool for producing stamped disks, including at least one stamping or fine blanking stage and at least one corrugating and embossing stage.

A method and a device for producing corrugated disks in two method steps is known from DE 10 2010 028 280 A1, wherein a workpiece is stamped or fine blanked in a first method step, transported between the first method step and a second method step, and corrugated and simultaneously deburred in the second method step. The method is carried out using a two-stage tool, the first stage of which is designed as a fine blanking stage and the second stage of which is designed as an embossing and corrugating stage.

Rollover typically develops during fine blanking, which in particular increases as the corner radius decreases and the sheet metal thickness increases. The rollover depth can be approximately 20%, and the rollover width can be approximately 30% of the sheet metal thickness or more (see DIN 3345, Fine blanking, August 1980), such that the lack of sharp edges on the outer teeth of the disks can result in limitation of the component function.

Moreover, forming of the thin and planar disk blank in the corrugating stage results in warpage, which impairs the shape accuracy of the outer and inner contours, and more significantly the shape and dimensional accuracy of the outer teeth of the disk. As a result, the installation and functional properties are adversely affected. Complex reworking is then required.

A method for producing stamped parts, in particular planar disks, is described in DE 196 08 551 A1 in which, in a first method step, the workpiece is stamped from the raw material inside a device. After stamping, the workpiece is moved to an embossing stage by way of transfer tongs, which are likewise accommodated in the device. The burr on the disk is compressed in the embossing stage. This prior art has the disadvantage that the disk on which the burr has been compressed must be corrugated in an additional processing stage—as described in EP 1 128 081 B1, for example—which considerably increases the complexity and costs in production.

SUMMARY OF THE INVENTION

The invention relates to a method and tool for producing stamped parts, in particular disks. An upper part and a lower part form at least one stamping or fine blanking stage for cutting the inner and outer contours of a disk blank, and at least one corrugating and embossing stage for corrugating the disk blank and for embossing burrs on the disk blank that developed during cutting. The corrugating and embossing stage is divided into a lower die part and an upper die part.

The invention further relates to a method for producing stamped disks, in which the outer and inner contours of a disk blank are cut in a first method step from a flat strip inside a tool. The tool includes the upper part and lower part in the stamping or fine blanking stage. The fine-blanked disk blank is moved, after the tool has been opened, by a cross slide into a corrugating and embossing stage. The disk blank is provided with a corrugated profile in a second method step by forming on an upper die part and a lower die part after the tool has been closed. The burrs on the disk that developed during fine blanking are compressed. The first method step and the second method step are carried out in one stroke.

An object of the invention is to provide a tool and a method for producing corrugated disks, by way of which it becomes possible to increase the shape and dimensional accuracy and the sharp edges of the outer teeth of the corrugated disks, while reducing costs.

According to the invention, by not carrying out the corrugating step simultaneously with the compression of the burr, but rather chronologically prior thereto, it is possible to fix, and not influence, the outer and inner contours of the disk during the corrugating step. This ensures accuracy of the shape and dimensions.

The invention includes an upper die part, which comprises an embossing bell, a stripper ring that is provided with an embossing surface and has a corrugated profile on the embossing surface, and an inner shape embossing element. In addition, a lower die part comprises an embossing anvil having a corrugated profile on the embossing surface thereof. The embossing bell and the inner shape embossing element are each provided with an embossing shoulder, which are disposed with respect to the corrugated profile of the stripper ring in the stroke direction (H) in such a way that the shoulders can seize the burrs after the corrugating step. As a result, the corrugating step takes place prior to the burr compression step, and the outer and inner contours of the disk are not able to change position, but are able to change shape on the burr side after the corrugating step.

It is particularly advantageous that the embossing bell for fixing the outer contour of the disk blank has an annular design and completely surrounds the outer contour, and that the inner shape embossing element is disposed supported against the inner contour. The outer and inner contours are thus fixed as if they were clamped, so that the outer and inner contours of the disk blank cannot be influenced by the forming operation.

According to a preferred variant embodiment of the tool according to the invention, the stripper ring is vertically supported on the inner wall of the embossing bell and on the outer wall of the inner shape embossing element. As a result, the embossing surface of the stripper ring is securely guided in a defined position relative to the disk blank.

In a further embodiment of the tool according to the invention, the inner wall of the embossing bell has a profile, which is adapted to the profile, and more particularly to the teeth, of the outer contour of the disk blank. This allows vertical guidance of the stripper ring, while also radially securing the outer contour against rotation of the disk blank during the forming operation.

In a refinement of the invention, the outer wall of the inner shape embossing element is adapted to the inner contour of the disk blank, so that the disk blank is likewise secured against radial rotation.

In a further embodiment of the tool according to the invention, the embossing anvil in the lower die part has an annular design and is associated with the stripper ring in the upper die part. A filler piece for transmitting the force and for providing support is disposed in the interior space of the embossing anvil.

It is of essential importance for the invention that the embossing shoulder is disposed on the inner wall of the embossing bell, and that the embossing shoulder of the inner shape embossing element is disposed on the outer wall of the same. The positions and shapes of the embossing shoulders are matched to the size and shape of the burr, the thickness of the disk blank, and the corrugated profiles of the embossing surfaces of the stripper ring and the embossing anvil. This ensures that the corrugating step can take place prior to burr compression on the burr side of the disk blank.

The lower die part moreover comprises an intermediate ring, which is vertically guided in a cavity frame and is adapted to the embossing bell. The ring surface of the bell forms a seat for the embossing bell when the upper die part and the lower die part are closed. The inner will is adapted to the fine-blanked outer contour of the disk blank. The disk blank is thus exactly situated in a defined position between the embossing surfaces of the stripper ring and the embossing anvil. Accordingly, the outer and inner contours are fixed by the embossing bell and the inner shape embossing element. The stripper ring, embossing anvil, embossing bell and the inner shape embossing element effectively form the die in which the forming operations are carried out.

According to a further embodiment of the tool according to the invention, the embossing bell is operatively connected via an upper pressure plate, and the inner shape embossing element is operatively connected via a further pressure plate, to a fixed upper block of the upper part for carrying out all operations. The upper block can, of course, also be designed so as to perform stroke movements. In such a case, the lower block is designed in a corresponding stationary manner.

The stripper ring, which in a further advantageous embodiment of the invention also performs a forming function, is operatively connected via a pressure pin and an upper ring plate to an additional hydraulic unit for stripping off the completely formed disk.

The cavity frame, in which the intermediate ring and the embossing anvil are vertically guided by way of a lower pressure plate and operatively connected to a lower additional hydraulic unit, is fixed in a stationary manner on the lower block. The lower block is connected to the press ram, so that the lower part of the tool is able to carry out a stroke movement for fixing, corrugating and compressing the disk blank.

In a further embodiment of the tool according to the invention, the embossing surfaces of the embossing anvil and of the stripper ring can have different embossing profiles that are matched to each other. For example a corrugated profile has uniformly shaped corrugation peaks and corrugation troughs. Or, an irregular corrugated profile comprising at least two corrugations has differently shaped and spaced corrugation peaks and corrugation troughs. As a result, disks having differing corrugations can be produced.

The object is further achieved by a method, according to which, in the corrugating and embossing stage, simultaneously with the disk blank corrugating step, the outer and inner contours are fixed so as to maintain the positions and shapes thereof during corrugating. The corrugating takes place prior to burr compression. The outer and inner contours of the disk are not able to change positions, but are able to change shapes on the burr side, due to the subsequent compression.

It is particularly advantageous that the top and bottom sides of the disk blank are corrugated by an embossing anvil that is associated with the lower die part and by a stripper ring that is associated with the upper die part. The stripper ring thus performs both a forming function and a stripping function for the corrugated disk.

In a further embodiment of the method according to the invention, different embossing profiles can be used as the embossing surfaces for the anvil and the stripper ring. For example a corrugated profile has uniformly shaped corrugation peaks and corrugation troughs. Or, an irregular corrugated profile comprising at least two corrugations has differently shaped and spaced corrugation peaks and corrugation troughs. Thus, the method according to the invention can be variably adapted to the different corrugation shapes and disk dimensions.

Further advantages, features and details of the invention will be apparent from the following description with reference to the accompanying drawings.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The invention shall be described in more detail hereafter based on the example of producing a disk having outer teeth. It is intended that the invention also encompass disks having inner teeth.

FIGS. 1aand 1bshow a commercially available corrugated outer disk1, which has an outer contour2having teeth3and a circular inner contour4, wherein the outer disk1is provided with a corrugation5(seeFIG. 1b). For example, the outer disk1has a thickness D of 1.8 mm and is made of steel.

The outer disk1is to be produced using a fine blanking tool6, which comprises an upper part7and a lower part8, which—as shown inFIGS. 2 and 3—form at least one fine blanking stage9and at least one corrugating and embossing stage10.

The upper block11of the upper part7is fixed in a stationary manner on a machine table, which is not shown, and the lower block12of the lower part8is fixed on a ram of a press so as to be able to perform stroke movements. The disk blank13is fine-blanked from bottom to top—which is to say in the direction of the upper part—from a flat strip14in the fine blanking stage9, which corresponds to the known prior art and therefore does not have be described in more detail.

The burrs15on the disk blank13protrude vertically upward on the outer contour2and the inner contour3of the disk blank13(see alsoFIG. 14c). After having been ejected from the fine blanking stage9, the fine-planked disk blank13is seized by a cross slide16and transported by the same into the corrugating and embossing stage10, where the disk blank is deposited in an accurately positioned manner prior to the corrugating step.

FIG. 3shows the basic design of the embossing and corrugating stage10when the same is closed. The embossing and corrugating stage10comprises an upper die part17and a lower die part18. The upper die part17includes an annular embossing bell19, an annular stripper ring20, and an inner shape embossing element21. The embossing bell19is fixed to an upper embossing pressure plate22in a stationary manner, the pressure plate in turn being fixed to the upper block11.

The stripper ring20is supported vertically on the inner wall23of the embossing bell19and horizontally on the upper embossing pressure plate22. The stripper ring20, on the side24thereof facing the embossing pressure plate22, is able to carry out a vertical relative movement with respect to the embossing bell19by way of a pressure pin27, which can be actuated by an upper additional hydraulic unit25and a ring plate26. The inner shape embossing element21, which vertically guides and supports the stripper ring20on the outer wall28, is inserted into the annular stripper ring20. A separate pressure plate29, which is operatively connected to the embossing pressure plate22for force transmission, and which is disposed in the annular stripper ring20, is seated on the inner shape embossing element21.

The lower die part18is formed by an annular cavity frame30, an intermediate ring31, an annular embossing anvil32, and a filler piece33. The cavity frame30is attached to the lower block12. The intermediate ring31, the embossing anvil32and the filler piece33are seated on a lower embossing pressure plate34, which in turn is operatively connected via a lower additional hydraulic unit35.

As is shown in enlarged form inFIG. 4, the embossing bell19, the stripper ring20and the inner shape embossing element21of the upper die part17, together with the intermediate ring31, the embossing anvil32and the filler piece33of the lower die part18, in each case form operative pairs with respect to the disk blank13.

The outer contour2of the disk blank13is surrounded by the embossing bell19, and the inner contour4of the same is surrounded by the inner shape embossing element21, so that no warpage can develop on the disk blank13during the corrugating step of the disk blank13between the stripper ring20and the embossing anvil30.

FIGS. 5 to 10illustrate the design of the upper die part17. It is clearly apparent that the inner wall23of the embossing bell19and the outer wall36aof the stripper ring20are matched to each other and together have contours K, which correspond to the outer contour2of the disk blank13. The inner shape embossing element21is disposed in a vertically guided manner in the annular stripper ring20.

FIGS. 6 and 7show a perspective view of the embossing bell19and a section along line A-A fromFIG. 6. On the centering edge37formed by the lower seat surface36and the inner wall23, the embossing bell19comprises an embossing shoulder38, the depth T of which is matched to the dimensions and shape of the upwardly protruding burr on the outer contour2, the thickness D of the outer disk1, and the height h of the corrugation peak of the corrugated profile.

FIG. 8shows the stripper ring2, which has a corrugated profile39on the embossing surface40thereof facing the embossing anvil32. This corrugated profile39is matched to the desired corrugation of the outer disk1.

The inner shape embossing element21has a cylindrical shape, and the contour thereof is matched to the inner contour4of the disk blank13(seeFIG. 9). It is apparent fromFIG. 10that, on the lower centering edge41thereof facing the upwardly protruding burr15on the inner contour4, the inner shape embossing element21has an embossing shoulder42, the depth t of which is matched to the dimensions and shape of the burr15, the thickness D of the outer disk1, and the height h of the corrugated profile.

The lower die part18is shown inFIG. 11, without the cavity frame. The inner wall43of the intermediate ring31and the outer wall44of the embossing anvil32have contours K that are matched to each other and correspond to the outer contour3of the disk blank13.

As is shown inFIG. 12, the embossing surface45of the embossing anvil32has a corrugated profile46, which is adapted to the desired corrugation of the outer disk1. Examples of corrugated profiles39and46on the stripper ring20and the embossing anvil32, respectively, are shown in development views inFIGS. 13ato 13caccording to the section line C-C inFIG. 11. In this way, depending on the requirements, corrugations that are distributed uniformly or non-uniformly on the circumference of the disk blank13can be provided, such as triple corrugations, quadruple corrugations or 2+2 corrugations.

The method according to the invention will be described based onFIGS. 14ato 14d. InFIG. 14a, the cross slide16has deposited the disk blank13on the embossing anvil32. Centering according the outer contour2of the disk blank13is carried out by the centering edge37of the embossing bell19, and centering according to the inner contour4is carried out by the centering edge41, so that the disk blank13becomes seated in an accurate position on the embossing anvil19for the clamped state (seeFIG. 14b).

FIG. 14cshows the state in which the corrugation peaks47of the corrugated profile39of the embossing surface40of the stripper ring20have reached the disk blank13due to the stroke movement of the embossing anvil32. The corrugation forming process on the disk blank starts and is completed before the embossing shoulders38and42of the embossing bell19and the inner shape forming element21, respectively, are able to seize the burr15on the outer contour2and the inner contour4.

After another stroke of the embossing anvil32, the embossing shoulders38and42reach the burr15and compress the same on the disk body. The embossing process is completed.

InFIG. 14d, the stripper ring20has stripped the outer disk1, which is corrugated and on which the burr has been compressed, off of the embossing shoulders38and42by way of the upper additional hydraulic unit25. After the tool is opened, the outer disk1can be transported on the toot by way of the cross slide16.