EP2722194B1 - Tool for machining workpieces, in particular sheet metal - Google Patents

Description

The invention relates to a tool for machining workpieces, in particular sheets, which has an upper tool with a machining tool and a lower tool with a counter-holder, wherein the upper tool and the lower tool are arranged opposite each other, so that the counter-holder on one side and the machining tool on the other side of an intermediate workpiece can be positioned.

From the EP 2 450 120 A1 For example, a burr-removing machine has become known which includes a tool therefor. This consists of an upper tool with a machining tool, such as a striker, and a lower tool, which is a counter-holder receives. The counter-holder is designed as a spring-loaded ball made of steel. During machining of the workpiece, the steel ball abuts on one side of a cutting edge of the workpiece. On the opposite side of the cutting edge is a striker used to remove the burr, the ball counteracts the work force of the striker.

From the US 2006/0042341 A1 shows a Entgratungswerkzeug, in which also on one side of the workpiece to be machined an upper tool with a machining tool and on the opposite side of a lower tool is provided with a counter-holder. For deburring the workpiece is proposed that both the machining tool and the lower tool are each formed as a ball, which are made of steel to equalize the burr during a movement by a contact pressure.

From the US 2007/0122224 A1 is another tool for machining workpieces, especially sheets out. An upper tool takes on a marking tool as a machining tool. Opposite, the lower tool comprises a ball as a counter-holder. Analog goes out of the US 2007/0105488 A1 out.

To edit the workpieces with the aforementioned tools they are moved between the upper and lower tool, the upper and lower tool are fed to the workpiece and rest, so that on the one hand the ball rests on one side of the workpiece and the machining tool on the opposite Workpiece attacks and works with pressure against the opposite ball. In this case, on the ball zugwandten side of the workpiece on the surface scratches, impressions or dents arise, which affect the quality of the workpiece.

The invention has for its object to provide a method for processing workpieces, in particular sheets, in which a Damage to the workpiece surface of the workpiece to be machined is missing, which engages a counter-holder of the tool.

This object is achieved by a method having the features of claim 1. As a result, the counter-holder embodied as a ball is softer than the workpiece to be machined or the workpiece surface to be machined, whereby, despite the contact pressure between the upper tool and the lower tool, there is no denting on or into the workpiece surface of the workpiece, no scratches on the workpiece Surface of the workpiece are formed. As a result, the processing quality of such workpieces can be increased.

According to a preferred embodiment of the invention, the outer edge zone of the ball is formed as a coating, which is applied to a core. This can be done on the one hand, a simple production of such a counter-holder. On the other hand, this coating can also be used as a wear indicator. Once this coating has damage, flaking or perforations, wear of the counter-holder can be detected and replaced.

Alternatively, the outer edge zone can also be formed by a sheath which is applied to the inner core. Such a jacket is usually much thicker than a coating educated. This also provides a wider choice of different materials that can form such a sheath. This also makes it possible to use different production methods. For example, the jacket can be produced both by vulcanization and by further polymerization processes. Such a jacket, like the coating, can form a wear indicator. The core of the ball may be formed of a harder material than the coating or sheath.

An alternative embodiment of the invention provides that the ball is formed of a solid material whose surface hardness is lower than that of the workpiece to be machined. This allows a cost-effective production of such an anvil.

Preferably, the at least outer edge zone of the ball or the ball itself is made of a thermoset, a thermoplastic, a thermoplastic elastomer or an elastomer, a synthetic fiber material, a non-ferrous metal, or a resilient natural product, such as e.g. a natural fiber, felt, cork, fur, leather, made. These materials are particularly suitable for preventing scratches on the surface and introducing deformations. At the same time, a cost-effective production can take place. Likewise, non-ferrous metals, such as brass or the like, can be used for the outer edge zone or a ball made of solid material, which are, for example, softer than the mostly made of steel workpieces.

Furthermore, a coating can be applied to the outer edge zone of the ball. This can be, for example, a paint or varnish layer. Such an additionally applied paint or varnish layer serves as a wear indicator in order to enable a timely replacement of the counter-holder if signs of wear occur.

An alternative embodiment of the counter-holder provides that the outer edge zone consists of two or more layers with divergent material properties, wherein the outer layer is more resistant to wear than the inner layer, but the outer layer has a lower surface hardness than the workpiece to be machined or having machined workpiece surface. As a result, the outer edge zone may be yielding to the core of the ball, but still have an increased wear potential, but without affecting the workpiece surface.

The counter-holder can be arranged in a receptacle of the lower tool, which is open towards the workpiece, wherein the counter-holder is arranged with a holding device for positioning the counter-holder in the receptacle, through which the counter-holder is resiliently received along a longitudinal axis of the lower tool in the receptacle , This allows a compliance of the counter-holder in a predetermined tolerance range during the machining of the workpiece in order to avoid an overload on the workpiece surface.

The holding device may be formed as a spring element which has a receiving portion for the arrangement of the counter-holder and fastening portions for fixing the spring element to the receptacle of the lower tool and comprises strip-shaped expansion portions in between. By such a spring element is structurally in a simple manner allows positioning of the counter-holder to the lower tool, At the same time can be adjusted by the strip-shaped Dehnabschnitte the holding device in a simple manner, the resilience of the counter-holder relative to the lower tool.

A further preferred embodiment of the holding device provides that when an overload of the lower tool, the counter-holder completely immersed in the receptacle with respect to an outer edge of the receptacle and the Dehnabschnitte the holding device are plastically deformed. Thus, the holding device serves as overload protection and simultaneously as an indicator of an overload, which may be caused for example by unevenness of the sheet, incorrect machining parameters, collisions, sheet metal vibrations or incorrect operation.

The machining tool in the upper tool or lower tool can be designed, for example, as a marking, embossing, film-separating, engraving, roll-deburring or roll-forming tool, in particular a rolling-punching tool. In all these machining tools, the ball-shaped counter-holder can be used with at least one outer edge zone, which has a lower surface hardness than the workpiece to be machined or the workpiece surface to be machined.

The method according to the invention provides that in a workpiece to be machined with a Vickers hardness in a range of 1000 to 10,000 MPa (N / mm ² ), such as steel, a steel alloy or stainless steel, at least the outer edge zone of the ball is formed with a Vickers hardness in a range of 200 to 1,000 MPa, preferably from 200 to 500 MPa, in particular when using non-ferrous metals. As a result, the processing quality of such workpieces can preferably be increased.

The method according to the invention provides alternatively that, in a workpiece to be machined with a Vickers hardness in a range between 200 to 1000 MPa, preferably from 200 to 500 MPa, which is in particular made of a non-ferrous metal, at least the outer edge zone of the ball with a llickers hardness of less than 200 MPa is formed. In this application, when it comes to the processing of non-ferrous metals, at least the outer edge zone of the ball is formed of plastic.

The invention and further advantageous embodiments and developments thereof are described in more detail below with reference to the examples shown in the drawings and explained.

Figur 1

eine perspektivische Ansicht einer Werkzeugmaschine,

Figur 2

eine schematische Schnittdarstellung eines Werkzeugs für eine Werkzeugmaschine gemäß Figur 1 mit einem Ober- und einem Unterwerkzeug in einer Ausgangsposition,

Figur 3

eine schematische Schnittdarstellung des Werkzeugs gemäß Figur 2 in einer Bearbeitungsposition,

Figur 4

eine schematische Schnittdarstellung des Werkzeugs gemäß Figur 2 in einer Überlastsituation und

Figur 5

eine schematische Ansicht einer Haltevorrichtung zur Aufnahme eines Gegenhalters im Unterwerkzeug gemäß Figur 2.

Show it:

FIG. 1

a perspective view of a machine tool,

FIG. 2

a schematic sectional view of a tool for a machine tool according to FIG. 1 With an upper and a lower tool in a starting position,

FIG. 3

a schematic sectional view of the tool according to FIG. 2 in a processing position,

FIG. 4

a schematic sectional view of the tool according to FIG. 2 in an overload situation and

FIG. 5

a schematic view of a holding device for receiving a counter-holder in the lower tool according to FIG. 2 ,

In FIG. 1 is perspective view of a machine tool 11 for machining workpieces 12, in particular plate-shaped workpieces 12, such as sheets, shown. The machining of workpieces may include punching, bending, signing, embossing, engraving, deburring, roll forming, in particular rolling pin, as well as a film roll of a film on the workpiece surface. The machine tool 11 has a C-shaped base frame 14 with an upper frame leg 15 and a lower frame leg 16. In a throat space between the upper frame leg 15 and the lower frame leg 16, a conventional coordinate guide 16 is housed. This serves for positioning or movement of the workpiece 12 relative to a processing station 18 of the machine tool 11 as well as for storage and replacement and replacement of tools 20 at the processing station 15th

At the processing station 18, a tool 20 is exchanged, which comprises an upper tool 21 and a lower tool 22. The lower tool 22 is arranged in a lower tool holder 23 on a machine table 25, which in turn rests on the lower frame legs 16 of the machine frame 14. The upper tool 21 is mounted on an upper tool holder 24 of a plunger 26. This is on the upper frame leg 15 of the frame 14 in the direction of a double arrow 27, for example, hydraulically movable up and down. To a Hubachse 28 of the plunger 26, both the upper tool 21 and the lower tool 22 in the direction of a double arrow 29 are adjustable or deliverable. Corresponding feed movements, like the other essential machine functions, are controlled by means of a schematically illustrated control 30 of the machine tool 11.

The workpiece 12 is held by means of a gripping device 32 during machining with the tool 20 and positioned the workpiece 12, which rests on the machine table 25, relative to the processing station 18. After completing a machined workpiece 34 this example, by lowering a table segment 35 of Machine table 25 led out of the processing station 18.

In FIG. 2 is shown schematically enlarged, the tool 20, wherein, for example, an upper tool 21 above and a lower tool 22 below the workpiece 12 is arranged. The arrangement of the upper tool 21 and the lower tool 22 may also be reversed. The representation in Figur2 is only an example.

The upper tool 21 comprises a main body 41, which comprises a holding shaft 42 and a downwardly open receptacle 43. In this receptacle 43, a counter-holder 45 is arranged with a counter-holder receptacle 46, which is resiliently mounted with a holding device 47. The counter-holder 45 is designed as a ball 48, which is freely rotatably mounted in the counter-holder receptacle 46. The counterholder receptacle 46 has a cylindrical guide section 49, which is displaceably guided along a longitudinal axis 50 of the tool 20 in a recess 51 in the main body 41.

In a starting position, the holding device 47 receives the counter-holder 45 in such a way that a region of the counter-holder 45 or a spherical segment protrudes from an outer edge 52 of the holder 43. The formed as a ball 48 counter-holder 45 is made according to a first embodiment of a core 54 and an outer edge zone 55, which completely surrounds the core 54. The outer edge zone 55 forms a rolling surface. The outer edge zone is formed of a material which has a lower surface hardness than the workpiece 12 to be machined or the workpiece surface to be machined. The outer edge zone 55 is softer than the workpiece surface to be machined. The surface hardness is determined by the Shore hardness of a material. The thickness or thickness of the outer edge zone 55 may be formed in the form of a coating. Likewise, this may be formed by a sheath or casing, which may include, for example, the half or three-quarter radius of the ball 48. The core 24 may for example be formed of a harder material than the outer edge zone 55. Likewise, the core 54 may also be formed of a softer material than the outer edge zone 55.

In an embodiment, not shown, the core 54 and the outer edge zone 55 may be made of the same material, that is, the ball 48 is made of a material. The ball 48 may be formed as a hollow ball or as solid material ball. However, the material used for this purpose is selected such that it has a lower surface hardness than the workpiece 12 to be machined or the workpiece surface to be machined. Furthermore, the ball 48 may alternatively consist solely of the outer edge zone 55, without further components or components are provided.

Furthermore, the counter-holder 45 may include a paint or varnish coating, which serves as a wear indicator. Likewise, the outer edge zone 55 itself serve as a wear indicator. Wear is indicated when the outer edge zone or coating has damage, perforations or flaking, that is, damage has occurred to the outer edge zone 55 of the anvil 45 as the ball 48 rolls on the workpiece surface of the workpiece 12.

The upper tool 21 opposite the lower tool 22 is arranged, which may also be referred to as a die. A base body 61 of the lower tool 22 receives a machining tool 62, which is driven by a plunger, not shown, which is guided by the lower frame legs 16. The lower tool 22 is mounted with its support shoulder 64 on the lower tool holder 23. The machining tool 62 is received in a receptacle 63. The receptacle 63 is received by a guide 65, which forms a part of a support plane 67 on the outside thereof. Furthermore, the receptacle 63 is positioned and biased by one or more force storage elements 68 to the guide 65. The receptacle 63 and the machining tool 62, which are connected to one another, can be displaced downward into the main body 61 in the event of an overload.

In the embodiment according to FIG. 2 For example, the counter-holder 65 is associated with the upper tool 21 and the machining tool 62 with the lower tool 22. This arrangement can be reversed as well as the positioning of the upper tool 21 and lower tool 22 to the workpiece 12. That is, for example, that the upper tool 21 can receive the machining tool 62 and the lower side of the workpiece 12 is assigned. Likewise, a permutation can be provided.

In FIG. 2 the tool 20 is arranged in a starting position 66 at the beginning or end of a machining step, that is, the upper tool 21 and lower tool 22 are positioned at a distance from the respective workpiece surface of the workpiece 12.

For machining the workpiece 12, the upper tool 21 and the lower tool 22 are supplied to the workpiece surface of the workpiece 12. Such a processing position 69 of the tool 20 is shown in FIG.

The machining tool 62 engages or engages a side of the workpiece 12 on the workpiece surface, such as in signing or engraving, as shown in FIG FIG. 3 is shown. Opposite lying the counter-holder 45 engages the workpiece 12 and counteracts the force acting on the workpiece 12 by the power tool 62 to avoid deformation. During the processing of the workpiece 12, the workpiece 12 can be moved relative to the tool 20 or the processing station 12. In this case, the machining tool 62 engages permanently or alternately on or at the workpiece surface of the workpiece 12. The ball 48 is located during the movement on the workpiece surface of the workpiece 12 continuously or alternately. In such a processing position 69, there is no or only a slight deflection of the holding device 47, so that a contact point of the ball 48 on the workpiece surface of the workpiece 12 with respect to the edge 52 of the receptacle 43 of the upper workpiece 21 continues to protrude.

The FIG. 4 shows the tool 20 in an overload position 71. In this overload position 71 of the outer edge 52 of the receptacle 43 of the upper tool 21 rests on the workpiece surface of the workpiece 12, wherein the ball 48 is completely immersed in the receptacle 43. The holding device 47 absorbs this immersion movement and retains this after lifting the upper tool 21 from the workpiece 12, as follows FIG. 5 is described. This ensures, on the one hand, that there is no effect on the workpiece surface for introducing deformations or other damage to the surface. On the other hand, the existing overload is signaled.

The holding device 47 has for carrying out these functions by way of example an embodiment according to FIG. 5 on. The holding device 47 is formed as a spring element, which is made for example of a plate-shaped workpiece. A receiving portion 73, which is formed for example circular, allows easy arrangement and positioning of the counter-holder receptacle 46, which is preferably cylindrical. The guide portion 49 of the anvil holder 46 is insertable into the receiving portion 73 and abuts the receiving portion 73 with a shoulder of the anvil holder 46. About attachment portions 74, the holding device 45 is preferably fixed in the receptacle 43. Between the fastening portions 74 and the receiving portion 73 strip-shaped expansion portions 75 are formed, which are indeed elastically deformable within a predetermined stroke or compression movement, but are plastically deformed under a load according to the overload position 71. Such a plastic deformation can be determined and selected by the choice of material as well as the cross section of the expansion sections 75.

Claims (12)

1. A method for machining workpieces (12), in particular sheet metal, using a tool (20) comprising an upper tool (21) which accommodates a machining tool (62) and a lower tool (22) which accommodates a back stop (45) that is shaped in the form of a ball (48), said upper tool (21) and said lower tool (22) being arranged opposite each other, such that the back stop (45) is positioned on one side and the machining tool (62) is positioned on the other side of the workpiece (12) which is arranged therebetween, characterised in that the ball (48) has at least one outer peripheral zone (55) which has a lower surface hardness than the workpiece (12) to be machined or the workpiece surface of the workpiece (12) to be machined, wherein

   - when a workpiece (12) that is to be machined has a Vickers hardness in a range of between 1,000 and 10,000 MPa, at least the outer peripheral zone of the ball (48) is made of a material having a Vickers hardness in a range of between 200 and 1,000 MPa or of a material having a Vickers hardness of less than 200 MPa, or

   - when a workpiece (12) that is to be machined has a Vickers hardness in a range of between 200 and 1,000 MPa, at least the outer peripheral zone of the ball (48) is made of a material having a Vickers hardness of less than 200 MPa.
2. The method as claimed in claim 1, characterised in that the outer peripheral zone (55) of the ball (48) is realised in the form of a coating or covering which is applied onto an inner core (54).
3. The method as claimed in claim 1, characterised in that the outer peripheral zone (55) extends over the entire cross-section of the ball (48) and in that the ball (48) is formed from solid material.
4. The method as claimed in any of the preceding claims, characterised in that the at least one outer peripheral zone (55) of the ball (48) is made of a thermosetting plastic, a thermoplastic resin, a thermoplastic elastomer, an elastomer, of a synthetic fibre material, of a non-ferrous metal or of an elastic natural product such as natural fibre, felt, cork, fur, leather.
5. The method as claimed in claim 1, characterised in that the outer peripheral zone (55) of the ball (48) has a colour coating or a paint coating applied thereon.
6. The method as claimed in claim 1, characterised in that the outer peripheral zone (55) of the ball (48) consists of two or more layers having material properties that differ from each other/one another, with the outer layer having a higher surface hardness than the inner layer.
7. The method as claimed in any of the preceding claims, characterised in that the back stop (45) is disposed within a mount (43) of the lower tool (22) which is open toward the workpiece (12) and in that for positioning the back stop (45) within the mount (43) a retainer (47) is provided by means of which the back stop (45) is accommodated in a resilient manner along the longitudinal axis (50) of the lower tool (22).
8. The method as claimed in claim 7, characterised in that the retainer (47) is realised in the form of a spring element which has in particular a mounting portion (73) for a back stop mount (46) as well as at least one fastening portion (74) permitting a fixation on, or within, the mount (43), and in that it comprises strip-shaped, stretchable portions (75) arranged therebetween.
9. The method as claimed in claim 7 or 8, characterised in that when an overload is exerted on the lower tool (22), the back stop (45) will completely retreat into the mount (43) relative to an outer rim (52) of the mount (43) and the stretchable portions (75) of the retainer (47) is plastically deformable.
10. The method as claimed in claim 1, characterised in that the machining tool (62) is realised in the form of a marking tool, an embossing tool, a film slitting tool, an engraving tool, a roller deburring tool or a roller forming tool, in particular a roller pinching tool.
11. The method as claimed in claim 1, characterised in that the outer peripheral zone of the ball (48) having a Vickers hardness in a range of between 200 MPa and 1,000 MPs is made of a non-ferrous metal.
12. The method as claimed in claim 1, characterised in that the outer peripheral zone of the ball (48) having a Vickers hardness of less than 200 MPa is made of a plastic material.

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