EP1554068B1 - Stripping device - Google Patents

Abstract

The stripper device has fastener part (4) for fixing to the punch, and an elastic element (21). A stripper element (15) surrounding the punch is in contact with the work piece, e.g. the metal plate, and is enclosed by a guide element (11). The elastic element is positioned outside the work piece contact area, between stripper element or guide element and punch and/or within the guide element. The guide element is a sleeve, an the stripper element has a mainly straight shaft (17) and a projecting collar (18). Part of the shaft is coated with lubricant. The stripper element is of bronze or a similar material, and the elastic element is of a spring-elastic flexible or self-restoring material.

Description

The invention relates to a stripping device for use with a cutting tool having a cutting element, in particular a punch, for machining a workpiece, in particular a bent sheet, wherein at least one attachment piece for attachment to the cutting tool, a resiliently disposed outside the workpiece contact area, a resilient element provided with the workpiece in contact and surrounding the cutting element stripping element and at least one guiding element guiding the stripping element, and a device for preventing rotation is provided for substantially preventing twisting of the stripping element. Such a stripping device is known from US-A-2 168 377.

Absitreifeinrichtungen are known in connection with various types of cutting tools (DE 196 05 113 A1, DE 40 35 938 A1, DE 42 35 972 A1 and WO 99/67038 A1). Such a stripping device is required, in particular for punch punches or other cutting elements stripping the machined workpiece, in particular sheet, of the cutting element, in particular punch to allow. During the cutting operation, in particular punching, a front surface of the scraper abuts the surface of the workpiece, slightly springs in as the workpiece passes through the punch and retracts out of the workpiece upon retraction of the cutting tool, so that withdrawal of e.g. Punch is ensured from the workpiece.

Various types of wipers are available on the market. Most have a mounting plate by means of which they can be attached to the cutting tool, in particular a punch mounting plate. The stripper body consists for example of a rubber spring made of a hard plastic whose front surface is formed according to the workpiece contour. The shape can here by Cropping done. The rubber spring surrounds the punch on all sides. The shape of the front surface of the scraper is not symmetrical in most cases, since the workpiece to be machined usually has an irregular shape.

From US 2,168,377 a scraper device for use with a punch for machining a flat flat sheet is known, in which on a specially designed holding plate of a cutting tool, an outer element is secured by screws and bolts. The outer element is provided on its inner side with a longitudinal opening, in which a scraper element and therein the punch are inserted. Between the scraper, the outer member and the punch a spring-elastic element in the form of a coil spring is inserted. The scraper element has a substantially straight portion and a cantilever portion which can be supported on a projection within the longitudinal opening of the outer member or is held on this, so as not to be pushed out of the element unintentionally.

US 1,723,935 discloses a similar construction of a wiper device as the above document. Like these, US 1,723,935 also uses a coil spring disposed within an outer guide sleeve between the punch, stripping element and a special attachment means for attachment to the cutting tool. The outer guide sleeve is screwed onto a fastening piece, which is fastened to a further fastening piece, which is connected via a flange with the cutting tool via a screw connection.

US 4,993,295 discloses a stripping device for use with a punch for machining a flat sheet, in which, as in US 1,723,935, guide surfaces between an outer guide sleeve and a stripping element are relatively short, so that it can come at higher loads to tilt the stripping element within the guide sleeve. As a resilient element different disc springs are provided, which are stacked within the guide sleeve so that each curved surfaces are directed towards each other. A punch is located within the resilient element.

The scraper also has the task of keeping the workpiece in the desired shape during the machining process. This is particularly important when punching to be made in the range of sheet metal edges, since due to the punching process there can easily occur deformations. However, the scraper should not deform the workpiece independently, but keep this only in the desired prefabricated form. In providing a rubber stamp scraper completely enclosing a punch with an irregular front facing to the sheet, this proves to be problematic when the scraper rotates around the punch after some punching operations. The surface shape of the scraper then does not match the surface shape of the sheet to be punched, so it can come in this case to quality problems and complaints.

DE 812 498 discloses for this purpose a stripping device for a punch with a helical spring, which is arranged between a stripper plate and a punch head. The coil spring surrounds the area of the punch. There are three strips provided, which are fixed between the punch head and stripper plate and maintain a distance between these two elements. The attachment via screws and slots, so that an adjustment of the distance between Abstreiferplatte and punch head is possible. A twisting of the stripper plate, however, is hardly possible due to the strips.

FR 1 456 310 discloses a stripping device comprising in one embodiment a coil spring and in another an elastic element interposed between two fixed plates. In the case of the second embodiment, a bolt is disposed between the two fixed plates, similar to that provided by the strips in DE 812 498 for stably connecting the two plates. By the bolt also twisting of the plates against each other can be prevented.

However, these documents do not disclose any possibility of adaptation to the particular shape of deformed sheets. In all publications always only straight sheets are punched. Especially in the automotive industry, however, it is necessary to provide stripping devices that adapt to the particular shapes of deformed sheets or can be easily adapted to these, leave essentially no marks on the stamped sheets and have a long service life, so are made so stable in that they endure a large number of strokes, in particular maintenance-free more than 1 million stroke. The stripping device should also be designed so that a simple and quick change and exchange of stripping devices can be made. This is not possible with the complicated attached to the cutting tool devices of the prior art.

To prevent twisting, the company Dayton Progress GmbH also known a spring-loaded steel scraper. An anti-rotation device for the punch is formed in that the punch is constricted in a partial region in cross-section and flattened rectangular.

In this area engages a portion of the scraper, which is attached to the steel scraper by means of screws.

This solution proves to be disadvantageous due to their susceptibility to failure because of limited stability in the field of small fastening screws and risk of breakage of the constricted punch. Since the individual parts of a scraper must fit exactly to each other and often a complicated mount is required, resulting in hand-made alternatives average prices of 1,800 EUR per piece. In comparison, the pure rubber scrapers, as described above, cost around 100 EUR each. In these, however, has the disadvantage that only small numbers for the application when punching a sheet from the inside, with only certain shapes in addition to the disadvantages already mentioned above are possible. In the steel scraper also has the disadvantage that the engaging portion of the steel scraper holding screws are very small and often do not endure the forces occurring permanently, especially since they are loaded transversely. The durability of a rubber scraper, as described above, is about 80,000 strokes, after which proper stripping is no longer ensured or possible and thus the process reliability of a production is impaired.

The present invention is therefore based on the object to provide an improved stripping device, which is stable, in particular an anti-rotation in hundredths of a millimeter range is possible and unilateral shear forces can be eliminated. In addition, just for the application in the automotive industry high stroke rates should be possible in particular more than 1 million stroke, so the durability and stability over the stripping devices of the prior art can be improved. The stripping device should also be comparatively inexpensive and as small as possible.

This object is achieved with a scraper device according to claim 1. Further developments of the invention are defined in the dependent claims.

Thereby a scraper for use with a cutting tool with a cutting element, in particular a punch, created in which a long durability of the resilient member is made possible, since this does not come into contact with the workpiece. In addition, it is preferably loaded centric and torque-free, whereby a non-uniform wear or stress is also prevented. It is thus a durability of the elastic element of over 1 million strokes possible. Due to the use of a manageable number of individual parts which fit into one another, the stripping device is more robust than the stripping devices of the prior art. Due to the use of a guide element, preferably of guide sleeves or guide bushes, a reproducible movement of the stripping device relative to the cutting tool or the cutting element, in particular a punch, is advantageously also possible. In addition, there is no longer any need to guide through columns, as is the case with many prior art wipers, to allow for a firm attachment in the cutting tool. By such columns in particular lateral forces are to be intercepted, which occur during the cutting process and can rotate or move the scraper. In addition, a more cost-effective solution is created than, for example, the usual manually-built steel scrapers of the prior art. This is made possible in particular by the fact that the production costs are much lower than with these products.

The placement of the resilient element outside the workpiece contact area brings various advantages. As a result, the resilient element is not constantly in contact with oils and fats, which attack and destroy it gradually. In addition, by the contact of the workpiece with the stripping element instead of the resilient element, a substantially unyielding contact surface is created, which enables the shape of the workpiece and vice versa is not deformed by the workpiece. Therefore, the stripping element particularly preferably consists of bronze or another material which can be adapted to the workpiece surface shape and which is strong enough so that it can not be deformed by the workpiece during the machining process. Preferably, such a material is selected, with which it is possible to make the stripping element individually with respect to its front surface shape in order to adapt it to the workpiece to be cut. The resilient element is preferably a rubber spring or is preferably made of another resilient, resilient and / or resilient material. Especially when using a rubber spring fatigue fracture, for example, a coil spring can be avoided.

The device for preventing rotation preferably comprises a scraper element of irregular shape in cross-section and / or a slot or polygon hole in the guide element. The stripping device according to the invention has, for preventing rotation, a pairing of scraper element and hole or opening in the guide element, which is designed asymmetrically, at least in one orientation, to ensure a one-to-one orientation of the scraper element. This can be, in particular, a slot with three straight and one bent side and a correspondingly designed stripping element. By the provision of a non-symmetrical in cross-section or at least partially asymmetrically shaped scraper element and in particular adapted thereto a cross-section of the opening in the Guide element, in which the stripping element is guided, twisting and misoriented installation of the stripping element in the guide element can be substantially avoided. By providing a slot or polygonal hole and / or an irregularly shaped in cross-section scraper element a clear position is specified during installation, so that the formed on its front surface corresponding to the workpiece contour stripping element can not be accidentally rotated in its position even when changing quickly. In addition, a faster assembly is possible because the exact position of the stripping element does not have to be determined first, but by the shape of the stripping and the opening in the guide element, preferably the guide sleeve or bushing, and the preferred provision of inner and outer guide surfaces on the Scraping element is specified. It is thus a faster, easier and more accurate installation of the stripping device on the cutting tool possible than is possible in the stripping devices of the prior art. This allows not only the quick and easy installation and replacement of a stripping element and the correct orientation and avoiding damage to the workpiece to be punched. Even complex shaped sheets can thus be processed substantially without damage, in particular also due to the advantageous possibility of adapting the front surface of the stripper to the shape of the workpiece, in particular sheets, whereby markings of the workpiece around the punched hole can be avoided around. In the stripping devices of the prior art, such markings can not be avoided on a regular basis since there is no adaptation of the front surface shape of the stripping element to the shape of the (punching) workpiece to be machined (molded sheet). For example, in the case of vehicle doors, after their three-dimensional shaping, holes are provided in the lower region, the punching of which is not possible with the devices of the prior art described above without damaging the door profile, since there is neither one Anti-rotation nor an adaptation of the shape of the front surface portion of the scraper is provided to the door profile.

Preferably, the resilient element is arranged between the stripping element or guide element and the cutting tool and / or within the guide element. As a result, contact of the resilient element with the workpiece is avoided. In addition, the resilient element is held firmly in the wiper. As a result, a uniform load is possible, which keeps the wear of the resilient element as low as possible. In addition, a defined position of the spring-elastic element is determined, at any time the same easily replacement of it is possible during wear.

Preferably, the stripping element and the resilient element surrounding the cutting element are aligned so that they are substantially torque-free and in particular centric resilient. This advantageously prevents uneven wear and tilting of the resilient element and of the stripping element. In addition, a reproducible position of the resilient element is specified in particular for the case of replacement, so that an exchange can be done quickly and easily.

Preferably, at least one guide sleeve as a guide element outside of the stripping element; arranged at least partially surrounding this surrounding and / or at least one guide bush as a guide element within the stripping element this leader. By providing a guide element, a guide of the stripping element is created, which allows a defined movement of the stripping element along the cutting element, in particular punch. In addition, the stripping element on its pointing to an inserted cutting element inside, in particular to its shaft, preferably at least one guide surface. In this way, a guidance of the stripping element is also possible along the cutting element, in particular of its shaft. It is thus an inner and outer guidance of the stripping possible. Tilting, as occurs in particular with rubber springs of the prior art, no longer has to be feared. Rather, the exact movement is retained even after more than 1,000,000 strokes.

Preferably, the stripping element has a substantially straight portion and a projecting portion, wherein guide surfaces are provided on the straight and the projecting portion of the stripping. Preferably, at least one guide surface between the stripping element and the guide element is provided, the length of which can be selected as a function of the forces acting on the stripping device, in particular thrust and lateral forces, to ensure a tilt-free guidance. By providing a straight and a cantilevered portion of the stripping an even better Verkippsicherung against the cutting element and the guide element is created because two guide surfaces are provided, which are arranged in particular at a distance from each other. The respective length of the guide surface or guide surfaces can be selected as a function of the forces acting on the stripping device. In this case, a longer guide surface is preferably selected when the forces occurring are higher.

To improve the sliding of the scraper element within the guide element, a lubricant, in particular a lubricant suitable for maintenance-free lubrication, in particular a solid lubricant, is preferably provided at least in a partial region of the straight section of the scraper element. The use of a solid lubricant proves to be particularly advantageous in the material pairing of bronze and hardened steel of the individual sliding elements. When Solid lubricant is particularly suitable a combination of oil and graphite. The provision in particular of a maintenance-free lubrication is not provided in the prior art, for example US 2,168,377, US 1,723,935 and US 4,993,295. There lubrication of the sliding surfaces can be accomplished only by dismantling the entire device. A maintenance-free lubrication proves to be advantageous due to the poor accessibility of the lubrication points and the otherwise long life of the stripping device.

Preferably, the guide element is integrally formed with the attachment piece or guide element and attachment piece are formed as zusammenfügbare elements. A one-piece design is particularly suitable for higher forces, since in this case an unintentional tilting of the guide element and attachment piece into each other need not be feared. The stability and compactness of the stripping device is thus increased. On the other hand, the formation of guide element and attachment piece is suitable as mating elements, especially at lower forces. As a result, in particular, only one fastening with only one fastening means, in particular a screw, can be advantageously selected. The attachment piece can thereby be made smaller and thus space-saving.

Particularly preferred is or are at least one projecting portion and / or protruding portion, in particular a claw- or clamp-shaped portion, provided on the circumference or edge of the attachment piece for encompassing a fastening device of the cutting tool. In this case, the attachment piece can be centered on the fastening device, in particular a fastening plate. A secure and centered attachment or locking of the stripping device on the cutting tool or its Fastening device is characterized by only a single fastener, in particular a screw, possible. Compatibility of the attachment piece with a standardized attachment plate of a cutting tool proves to be very advantageous since it does not require the production of individual parts as in the case of the stripping devices of the prior art described above and a fit of fit is provided on each existing attachment plate. A quick and easy replacement of a scraper is therefore possible even for inexperienced operators.

Particularly preferably, the stripping device is used together with a wedge drive, since not only particularly high forces can be transmitted with such, but this must also be particularly accurate. The anti-rotation is here in the hundredths of a millimeter range, which can not be achieved with the stripping devices of the prior art.

Figur 1

eine Prinzipskizze eines in ein Schneidwerkzeug eingebauten Lochstempels mit erfindungsgemäßer Abstreifeinrichtung während des Stanzvorgangs eines Blechs,

Figur 2

eine Schnittansicht einer ersten Ausführungsform einer erfindungsgemäßen Abstreifeinrichtung,

Figur 3

eine um 90° gedrehte Schnittansicht durch die Abstreifeinrichtung gemäß Figur 2,

Figur 4

eine Draufsicht auf die Abstreifeinrichtung gemäß Figur 2,

Figur 5

eine Längsschnittansicht einer zweiten Ausführungsform einer erfindungsgemäßen Abstreifeinrichtung zur Verwendung bei mittleren auftretenden Kräften,

Figur 6

eine Draufsicht auf die Ausführungsform gemäß Figur 5,

Figur 7

eine um 90° gedrehte Längsschnittansicht der Abstreifeinrichtung gemäß Figur 5,

Figur 8

eine Draufsicht auf eine weitere Ausführungsform einer erfindungsgemäßen Abstreifeinrichtung mit einem um 90° gegenüber der Ausführungsform in Figur 6 gedrehten Abstreifelement,

Figur 9

eine Längsschnittansicht einer Abstreifeinrichtung für starke auftretende Kräfte, die nicht Teil der Erfindung ist,

Figur 10

eine Längsschnittansicht der Abstreifeinrichtung gemäß Figur 9 und

Figur 11

eine Draufsicht auf die Abstreifeinrichtung gemäß Figur 9.

For a more detailed explanation of the invention, individual embodiments will be described in more detail below with reference to the drawings. These show in:

FIG. 1

a schematic diagram of a built-in a cutting tool punch with inventive stripper during the punching operation of a sheet,

FIG. 2

a sectional view of a first embodiment of a stripping device according to the invention,

FIG. 3

a 90 ° rotated sectional view through the stripping device according to Figure 2,

FIG. 4

a top view of the stripping device according to Figure 2,

FIG. 5

a longitudinal sectional view of a second embodiment of a stripping device according to the invention for use with average forces occurring,

FIG. 6

a top view of the embodiment of Figure 5,

FIG. 7

a 90 ° rotated longitudinal sectional view of the stripping device according to Figure 5,

FIG. 8

a top view of a further embodiment of a stripping device according to the invention with a rotated by 90 ° relative to the embodiment in Figure 6 stripping,

FIG. 9

a longitudinal sectional view of a stripping means for strong forces, which is not part of the invention,

FIG. 10

a longitudinal sectional view of the stripping device according to Figure 9 and

FIG. 11

a top view of the stripping device according to FIG. 9

1 shows a schematic diagram of a cutting tool 1 in the region of the detail of a punch 2 with surrounding scraping device 3. The stripping device 3 is attached via a mounting plate 4 to a mounting plate 5 of the punch. The mounting plate 5 is in turn mounted on the cutting tool 1. The mounting plate 5 has a standardized shape. FIG. 1 shows the situation in which the punch punctures a metal sheet 6 as a workpiece to be machined. The sheet abuts against a front surface 7 of the stripper 3 during the punching operation. The punch plunges after penetrating the sheet in a counter punch 8 a. The punched out of the sheet section falls through a provided in the counter punch through hole 9 in a not shown collecting container into it.

As can be seen clearly from FIG. 1, the stripping device has a front surface shape corresponding to the sheet metal form. As a result, the sheet is supported during the punching operation and at the same time not deformed. The shape of the front surface of the stripping device can be made on site with the respective user. Depending on the forces that occur, the stripping device can each be designed differently, as shown individually in the following figures. FIGS. 2 to 4 indicate an embodiment which is more suitable for lower forces, FIGS. 5 to 8 an embodiment which is suitable for stronger forces, and the embodiment according to FIGS. 9 to 11 a variant which is suitable for high forces is. Accordingly different, the front surfaces of the stripping devices can be formed.

FIG. 2 shows a longitudinal sectional view of a first embodiment of the stripping device 3. The stripping device 3 is attached via the mounting plate 4 to the mounting plate 5 of the cutting tool, as can be better taken in particular Figure 3. This is done in this embodiment only by an indicated screw 10, better to see Figure 4. The mounting plate 4 attaches a guide sleeve 11 of the stripping device. As can be seen in Figures 2 and 3, the mounting plate 4 projects inwardly in its upper portion and engages over a projecting below portion 12 of the inserted into the mounting plate guide sleeve. As can be seen in particular from FIG. 4, the projecting portion 12 is provided only along a portion of the circumference of the guide sleeve. This is sufficient to hold the guide sleeve and secure against tilting. In the region in which the screw 10 is inserted through the mounting plate, the guide sleeve is formed without cantilevered portion, as well as in the 90 ° offset thereto region, which can be seen in Figure 4 on the left. As a result, a displacement of the guide sleeve is made possible by 90 ° within the mounting plate. A provided in an upper end plate 13 of the guide sleeve elongated hole 14, which may alternatively be a polygonal hole, this can also be offset by 90 °, which is advantageous in certain applications proves that as a result less different stripping devices must be provided.

The guide sleeve 11 is substantially cylindrical and provided in its upper region with the substantially perpendicular to the lateral surface of the guide sleeve extending end plate 13 with slot 14. Within the guide sleeve and the elongated hole a stripping element 15 is arranged. The stripping element 15 is guided within the guide sleeve and slidable. This is made possible by providing a lubricant 16, in particular a solid lubricant. The stripping element has a straight section 17 and a projecting section 18. The lubricant 16 is provided in the region of the straight portion 17. The projecting portion 18 extends substantially to the inner surface 19 of the guide sleeve and is slidably guided on this guide surface. As can be seen in particular Figure 3, the cantilevered portion 18 is not provided over the entire circumference of the stripping element 15 around, but only along the longitudinal sides. The straight section therefore has a different wall thickness, as can be seen in Figures 2 and 3.

The slot and the stripping have an irregular cross-section. This is characterized by three straight sides 141, 142, 143 and a curved side 144. Between the two long straight sides 141, 142 and the short straight side 143 are each provided with radii corner transitions 145, 146 are formed. Due to this irregular and at least partially asymmetrical configuration of the cross sections can be ensured during installation of the stripping its correct orientation, with faster and easy installation. In addition, advantageously just comparatively large surfaces are provided on the stripping element for absorbing forces when generating an anti-twist device.

In order to provide cushioning and return mechanism, an elastic element 21, e.g. provided in the form of a rubber spring, this surrounds, as well as the stripping element 15 the punch. In contrast to the stripping element, however, it is arranged concentrically with essentially the same wall thickness around the punch. On the other side of the spring-elastic element, a holding plate 22 is arranged, whose outer surface 23 is substantially flush with the outer surface 24 of the mounting plate 4. As a result, a defined counter surface is generated for supporting the resilient element.

On the mounting plate 4, a region 50 projecting beyond the actual outer surface 24 at the edge and a further section 51 protruding in the manner of claws or clamps are provided. This is best seen in Figure 4. The protruding portion 50 and the protruding portion 51 surround the outer edge 52 of the mounting plate 5 of the cutting tool. As a result, a centering of the mounting plate 4 and thus the entire stripping device 3 and a secure locking by the only one screw 10 on the mounting plate 5 of the cutting tool is possible.

The stripping element 15 is guided in the region of the slot 14 in the end plate 13 from the outside and along its passage opening 25 on the hole punch to be inserted through it from the inside. The seat on the punch is this preferably carried out as a snug fit.

The front surface of the scraper element 15 is chamfered or shaped according to the workpiece shape. Also, the already provided in the stripping element through hole 25 for performing the punch is driven completely through the stripping, as already indicated by the dotted lines in the Figures 2 and 3 is indicated. Preferably, in this embodiment, a bevel angle α of up to 5 ° is selected. For larger bevel angles, one of the embodiments according to FIGS. 5 to 8 is preferably selected. In these, the bevel angle α is preferably up to 10 °. The other shape of the front surface of the stripping element 15 is preferably adapted to the shape of the workpiece to be machined, in particular complex shaped sheet metal. By this adaptation, it is also possible to avoid unwanted caused by the scraper markings on the surface of the punched workpiece. Such particular circular markings occur regularly in the devices of the prior art and lead to a lesser quality of the punched workpieces or rejects.
In contrast to the embodiment according to FIGS. 2 to 4, in the embodiments according to FIGS. 5 to 8 the fastening plate is formed integrally with the guide sleeve. This guide sleeve 26 is also longer in the region of its straight portion 27 formed as the guide sleeve 11 according to Figure 2 and 3. The mounting plate portion 28 of the guide sleeve 26 has a greater material thickness than the mounting plate 4 according to Figures 2 and 3. In addition, in her how Figures 6 and 8 can be seen, two fastening screws 10 and two dowel pins 53 are provided for attachment to the cutting tool or on the mounting plate of the punch. By the thicker mounting plate part 1 is given a greater stability, whereby greater lateral and thrust forces can be compensated.

In contrast to the embodiments according to Figures 2 to 4, the guide sleeve is formed so long that it can be applied directly to the cutting tool and thereby covers the mounting plate 5 of the punch with particular standardized shape with. This can be taken in particular from FIGS. 5 and 7. The covering is only one-sided, as FIG. 5 shows, Similar to the above region 50 according to Figures 2 to 4, which is why the jacket of the guide sleeve is not formed uniformly long. In the region of the mounting plate of the punch, the guide sleeve is formed shorter to end above this.

The difference between the embodiments according to FIGS. 5 to 7 and 8 is that although in both cases a slot or polygonal hole is provided, this is offset by 90 °. This possibility has already been addressed to FIGS. 2 to 4. The rotation of the stripping element or guide sleeve by 90 ° becomes clear from FIGS. 6 and 8. The rest of the design of the stripping element and the guide sleeve and of the resilient element and the retaining washer are substantially identical in both embodiments. In all the illustrated embodiments, after installation and mounting, unintentional twisting is no longer possible because of the provision of the elongated hole 31 with three straight sides 311, 312, 313 and a curved side 314 and with radiused corner transitions 315, 316 or any other formed hole and the corresponding formation of the stripping a rotation is provided, which is in the hundredths of a millimeter range. Preferably, the stripping element made of high quality bronze. The guide sleeve is preferably made of steel. Due to this combination of materials, a particularly high-quality guidance of the stripping element can be produced in the steel body of the guide sleeve, wherein a long life or service life of the stripping device can be created. This is about five to ten times the previously known stripping. Wear part is only the elastic element. However, this holds more than 1 million stroke long and thus a multiple of the durability of the known stripping.

By the projecting portion 18 of the stripping element, which corresponds to the dimensions of the stripping element according to Figure 2 to 4, can In addition to the rotation also a stroke limitation can be generated. This happens because this can be moved to a maximum of just before the end plate 13 and 29 respectively. By providing the rotation in the form of the elongated hole 14, 31 and the corresponding formation of the stripping element, shear forces can be intercepted in addition to the guiding function. Depending on the application, it is also possible to make an adjustment to different shank diameter of the punch by differently sized through holes 25 and 30 of the stripping element or the through hole 32 of the resilient element. Larger lateral forces can also be absorbed by the larger guide length of the guide sleeve. The guide takes place, as in FIGS. 2 to 4, with respect to the stripping element, from inside and outside, ie in the end plate 29 of the guide sleeve 26 and on the punch along the passage opening 32 of the stripping element 15. Despite the sometimes very different shape of the front surface of the stripping element At the stripping attacking moments are optimally intercepted by the provision of the guide surface pairings and the device for preventing rotation.

FIGS. 9 to 11 show a stripping device not belonging to the invention, which is suitable for particularly high shear forces or lateral forces. In this embodiment, guide bushes 33 are provided instead of guide sleeves, wherein the guide bushes 33 are arranged within a stripping element 34. The guide bush 33 runs on the punch, not shown. For this purpose, it has an inner passage opening 35. The stripping element 34 is formed larger than in Figures 2 to 8. It is trapezoidal, with large through holes 39, in which fasteners for attaching the scraper sit on the cutting tool. This area of the wiper element is the mounting section, which instead of a separate mounting plate and a mounting portion as in Figure 5 to 8 is formed on the stripping element itself. In order to better absorb lateral or shear forces, an attachment to the cutting tool via two fitting shoulder screws 36 is provided, These sit in guide bushes 37, 38, which are inserted into paragraphs in the through holes 39. As can be seen from Figure 11, the pass-shoulder screws 36 are mounted directly in the cutting tool, on both sides surrounding the mounting plate 5 for the punch. This corresponds to the structure according to Figure 5 to 8. The guide length of the stripping element is compared to the embodiments according to Figures 2 to 4 and 5 to 8 again increased, this being determined by the shape of the scraper and the type of attachment via three guide bushes. Here, a guide of the stripping element from the outside and from the inside is provided, as can be seen particularly Figure 9, on the punch and on the pass-shoulder screws. This embodiment is secured against accidental rotation by providing a special shape of the region of the wiper element surrounding the two fitting shoulder screws 36 for embracing the fastening plate 5 and the fastening by means of the two fitting shoulder screws on the cutting tool (see in particular FIG. 11).

In addition to the embodiments described in the foregoing and illustrated in the figures, numerous others can be formed, in each of which a stripping element which comes into contact with the workpiece and surrounds a cutting element, at least one guide device guiding the stripping element and an anti-twist device are provided on the stripping element. A likewise provided elastic element is arranged outside the workpiece contact area and serves only for damping and resetting of the stripping.

LIST OF REFERENCE NUMBERS

1

cutting tool

2

punch

3

stripping

4

mounting plate

5

mounting plate

6

sheet

7

front surface

8th

counterpunch

9

Through opening

10

screw

11

guide sleeve

12

projecting section

13

End plate

14

Long hole

15

stripping element

16

lubricant

17

straight section

18

projecting section

19

palm

20

bottom

21

elastic element

22

retaining washer

23

outer surface

24

outer surface

25

Through opening

26

guide sleeve

27

straight section

28

Mounting plate part

29

End plate

30

Through opening

31

Long hole

32

Through opening

33

guide bush

34

stripping element

35

Through opening

36

Pass shoulder screw

37

guide bush

38

guide bush

39

Through opening

40

Attachment section

50

protruding area

51

projecting section

52

outer edge

53

dowel

141

long straight side

142

long straight side

143

short straight side

144

curved side

145

corner transition

146

corner transition

311

long straight side

312

long straight side

313

short straight side

314

curved side

315

corner transition

316

corner transition

α

taper

Claims (14)

1. Stripping device (3) for use with a cutting tool (1) with a cutting element, in particular a punch (2), for processing a workpiece, in particular a bent metal sheet (6), there being provided at least one fastening piece (4, 28, 40) for fastening to the cutting tool, a spring-elastic element (21) arranged outside the workpiece contact region, a stripping element (15, 34) which comes into contact with the workpiece and surrounds the cutting element (2), at least one guide element (11, 26, 33) guiding the stripping element (15, 34), and a device for securing against rotation for essentially preventing the stripping element (15) from rotating, characterised in that the device for securing against rotation has a pairing, formed asymmetrically at least in one direction, of stripping element and a hole or an opening in the guide element in which to fit the stripping element so as to ensure that the stripping element is installed with a unique orientation.
2. Stripping device (3) according to Claim 1, characterised in that the device for securing against rotation comprises a stripping element with an irregular cross-sectional shape.
3. Stripping device (3) according to Claim 1 or 2, characterised in that the device for securing against rotation comprises an elongated hole (14) or polygonal hole in the guide element.
4. Stripping device (3) according to one of the preceding claims, characterised in that an elongated hole having three straight sides (141, 142, 143, 311, 312, 313) and one curved side (144, 314) and a correspondingly designed stripping element (15) are provided.
5. Stripping device (3) according to one of the preceding claims, characterised in that at least one guide sleeve (11, 26) is arranged as a guide element outside the stripping element (15), at least partially surrounding the latter in a guiding manner, and/or in that at least one guide bushing (33) is arranged as a guide element within the stripping element (34), guiding the latter.
6. Stripping device (3) according to one of the preceding claims, characterised in that at least one guide surface (19) is provided between stripping element (15) and guide element (11, 26), the length of which surface can be selected as a function of the forces acting on the stripping device, in particular shearing and lateral forces, in order to ensure tilt-free guidance.
7. Stripping device (3) according to Claim 6, characterised in that the stripping element (15) has an essentially straight section (17) and a protruding section (18), guide surfaces being provided on the straight and the protruding sections (17, 18) of the stripping element (15).
8. Stripping device (3) according to one of the preceding claims, characterised in that the stripping element (15, 34) has at least one guide surface on its inside facing a fitted cutting element (2), in particular the stem thereof, and/or the stripping element (15, 34) and the spring-elastic element (21) are oriented, surrounding the cutting element (2), in such a manner that they can be loaded in a manner essentially free from torque.
9. Stripping device (3) according to one of the preceding claims, characterised in that a lubricant (16), in particular a solid lubricant, is provided at least in a subregion of the straight section (17).
10. Stripping device (3) according to one of the preceding claims, characterised in that the guide element (26) is formed integrally with the fastening piece (28) or guide element (11) and fastening piece (4) are formed as elements which can be joined together.
11. Stripping device (3) according to one of the preceding claims, characterised in that the spring-elastic element (21) is arranged between stripping element (15) or guide element (33) and cutting tool (1) and/or within the guide element (11, 26).
12. Stripping device (3) according to one of the preceding claims, characterised in that at least one protruding region (50) and/or protruding section (51), in particular a claw- or clamp-shaped section, is or are provided on the circumference of the fastening piece (4) for engaging around a fastening device (5) of the cutting tool (1), in particular standardised fastening plate.
13. Stripping device (3) according to one of the preceding claims, characterised in that the stripping element (15, 34) can be provided or is provided with a shape corresponding to the workpiece and consists, in particular, of bronze or another material which can be machined and matched to the shape of the workpiece surface.
14. Stripping device (3) according to one of the preceding claims, characterised in that the spring-elastic element (21) is a rubber spring or consists of another spring-elastic, restoring or flexible material.

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