Bending mandrel or bending die for an apparatus for bending metal profiles, and corresponding bending apparatus

Abstract

The invention relates to a bending mandrel (1) or bending die (2) for a bending apparatus (100) for bending metal profiles (200), in particular flat rails, wherein the bending mandrel (1) or bending die (2) is formed in multiple parts and has a bending radius (3), characterized in that the bending mandrel (1) or bending die (2) has a radius piece (4), which has the bending radius (3), and a main piece (5), on which the radius piece (4) is detachably mounted. The invention also relates to a corresponding bending apparatus (100).

Description

[0001] Bending mandrel or bending punch for a device for bending metal profiles and a corresponding bending device

[0002] The invention relates to a bending mandrel or bending die for a device for bending metal profiles, in particular flat rails, wherein the bending mandrel or bending die has a bending radius and is made in multiple parts. A bending device with a bending mandrel or bending die is described in DE 198234901U1. A bending prism is known from DE 1946031 U.

[0003] Further state of the art is described in JP H11 - 114627 A, JP 3147993 U, DE 21 17245 A, EP 2641 668 A1 and DE 4409556 A1.

[0004] For the manufacture of electrical switchgear, it is often necessary to bend busbars, which are designed as copper busbars and typically have a rectangular cross-section, especially flat busbars, to accommodate a change in the direction of a power supply line within the electrical switchgear. Bending devices for bending metal profiles, also known as horizontal bending machines, are used for this purpose. These devices incorporate bending mandrels or bending punches, as described in DE198234901U1. A bending prism and a bending mandrel or a bending punch are positioned opposite each other on a horizontal worktable. Depending on whether the bending prism is fixed to a counter-holder and thus static, or whether it is arranged on a bending ram and thus hydraulically, electrically, or pneumatically adjustable and approachable opposite the counter-holder, the other tool is designed as a bending mandrel or a bending punch.The bending mandrel and the bending die have a bending radius which, in conjunction with the bending prism, causes the metal profile to be formed. The bending radius extends axially perpendicular to the worktable and radially parallel to it, thus forming a vertical edge around which a metal profile can be bent.

[0005] Often, depending on the installation side of the bending prism, the corresponding bending radius is implemented as either a bending punch or a bending mandrel. If the bending tool is used on the operator side, a bending punch is employed. If the tool is mounted on the opposite side of the movable bending ram, a bending mandrel is used on the operator side.

[0006] Currently, a complete bending mandrel or bending die is used for each desired radius. If the same radii are required for both bending dies and bending mandrels, a suitable bending die and a bending mandrel are needed. If the bending radius is worn, the entire part must be replaced, even if only the lower, more frequently stressed area facing the worktable is worn.

[0007] When changing the radius on the bending mandrel, the entire mandrel must be replaced. This often requires loosening a screw beneath the tabletop of the workbench, which secures the bending mandrel to the table, opening the tie rod (the counter-support at the top of the mandrel), and pulling the mandrel out. The new mandrel must then be inserted and installed in reverse order.

[0008] The production of bending dies and mandrels is relatively complex and therefore time-consuming. The parts must be surface-hardened to ensure a longer service life for the bending radii. It must be ensured that they are not through-hardened. In the case of mandrels, through-hardened parts can create a dangerous situation for the operator if they break and the force is released suddenly.

[0009] The object of the invention is therefore to propose a bending punch or bending mandrel which is cost-effective to use, easy to restore in case of wear, and allows safe operation for the user.

[0010] This problem is solved by a bending die or bending mandrel with the features of claim 1. Dependent claim 15 relates to a corresponding bending device. Advantageous embodiments are the subject of the dependent claims.

[0011] Accordingly, the bending mandrel or bending die is designed to have a radius element defining the bending radius and a base to which the radius element is detachably mounted. The bending mandrel or bending die can be multi-part, particularly two-part. In any case, it is multi-part in that the bending radius, in the form of the radius element, is a separate, replaceable component independent of the base. The radius element can be replaced if the bending radius becomes worn, while the other components of the bending mandrel or bending die can remain on the bending device.

[0012] Because the radius piece and the base are separate components, they can be manufactured independently and, in particular, meet different requirements regarding their material hardness. For example, the radius piece can be manufactured as a fully hardened component, thus eliminating the need for a complex and less reliable surface hardening process. The base can be made of unhardened tool steel. Its sole purpose may be to securely hold the radius piece against the forces generated during bending. If the bending mandrel or die is a two-part design, the base can serve as a holder for the radius piece. The radius piece can be screwed to the base from its rear side using at least one screw, preferably several.Other connections are conceivable, for example an undercut tongue and groove connection can be provided, perhaps with a T-slot on one side and a T-nut on the other.

[0013] The radius pieces of the bending mandrel and bending die can be designed as identical parts. In this case, the radius pieces can be mounted on either the bending die or the bending mandrel. When the radius piece is replaced, the base can remain on the bending device. The fastener, for example, at least one screw, can be freely accessible on the base when the base is mounted on the bending device. Accordingly, the radius piece on the bending mandrel or bending die can be replaced while the device is installed.

[0014] The radius element can be fixed to the workpiece in two positions rotated 180° relative to each other. A tongue-and-groove connection between the radius element and the workpiece can be used for this purpose. This allows the radius element to wear evenly along the length of the bending radius, resulting in a longer service life for the bending radius, especially when processing materials with small cross-sections. When the bending radius is worn, only the radius element needs to be replaced. This is more cost-effective and resource-efficient than conventional solutions. The radius element can be, for example, directly eroded or milled from a carbide block. The radius element can be made of carbide or hardened after machining. The radius element can be fully hardened, or only the bending radius can be hardened. For cost-effective manufacturing, the radius element can be milled and case-hardened.The material may be unhardened. Therefore, particularly when using a bending mandrel, even in the case of faulty manufacturing, for example, accidental through-hardening of the radius piece, there is a significantly lower risk of injury from brittle, splintering material compared to one-piece bending mandrels from the prior art that were accidentally through-hardened.

[0015] The radius piece can be fixed to the base by at least one detachable connection, preferably a screw connection. The base can have at least one through hole, and the radius piece can have at least one blind hole with an internal thread, aligned with the through hole. The radius piece can be fixed to the base by at least one screw extending from a rear side of the base facing away from the radius piece, through the through hole in the base, and into the blind hole, where it is screwed in. If the radius piece is fixed to the base by a positive fit, for example, by a tongue-and-groove connection extending in the axial direction of the bending radius, the screw connection between the base and the radius piece does not need to withstand any forces and can therefore be of a simple design.

[0016] When the bending mandrel is installed in the bending device, the at least one screw connection that secures the radius piece to the workpiece can be exposed on the back side of the workpiece opposite the radius piece. This back side can serve as a support surface for the bending mandrel against a counter-support of the bending device.

[0017] The bending die can be fixed to the bending device via a tool holder, whereby the tool holder may have an opening, for example, a slot, through which the rear side of the workpiece facing away from the radius piece is exposed, and a screw, in particular its screw head with its tool holder, is accessible for operation with a screwdriver. The workpiece of the bending die can thus remain on the bending device even if the radius piece is to be replaced, for example, in case of wear, or fixed to the workpiece in a position rotated by 180°. The radius piece can have symmetrical and identical fastening means along its axial direction to facilitate assembly in the two 180° rotated positions. Alternatively, the radius piece can have a single fastening means, for example, a single blind hole with an internal thread at a pivot point of the radius piece.exhibit at half the length of the radius segment along the axial direction of the bending radius.

[0018] The through-hole can extend between a support surface for supporting the bending mandrel on a counter-holder of a device for bending metal profiles and a side of the bending mandrel opposite the support surface, in particular a positive fit on the opposite side.

[0019] The radius element can rest against the surface on its side facing away from the bending radius via at least one positive fit. On its side facing the surface, the radius element can have a groove or tongue extending between opposing end faces of the radius element, or an elongated recess, or a projection complementary to an elongated recess. The radius element can have a constant cross-section at least partially along the axial direction of the bending radius. Preferably, the radius element, at least when it is the radius element of a bending die, has a constant cross-section over its entire length in the axial direction of the bending radius.

[0020] The radius piece, especially if it is the radius piece of a bending die, can be connected to the ground on a side facing away from the bending radius via at least one tongue and groove joint, for example via a rectangular or undercut tongue and groove joint, a wedge-shaped tongue and groove joint, a round profile tongue and groove joint, a dovetail tongue and groove joint, or a T-tongue and groove joint.

[0021] The workpiece can have at least one through hole, and the radius piece can have at least one blind hole with an internal thread, aligned with the through hole. The through hole and the blind hole can each open into one of the tongue and groove of the tongue-and-groove joint. Instead of an undercut tongue-and-groove joint, the workpiece and the radius piece, particularly when they form a bending mandrel, can be connected to each other via a simple positive fit without a force-fit connection, wherein the through hole and / or the blind hole is formed in the area of ​​the positive fit. For example, the through hole or the blind hole can extend through a recess or projection of the positive fit.

[0022] The tongue and groove of the tongue-and-groove joint can be continuous along the entire length of the joint on opposite sides of the flat and radius pieces, preferably as a sliding tongue-and-groove joint, allowing the radius piece and flat to be slid onto the flat along the tongue-and-groove joint. This simplifies the replacement of the radius piece while the flat can remain on the bending device.

[0023] The radius element can have a constant cross-section in the axial direction of the bending radius, preferably over its entire length in the axial direction, and particularly preferably over the entire length of the radius element between its opposing end faces. This makes the radius element easy to manufacture, and in some embodiments, it can be fixed to the workpiece in two positions rotated 180° relative to each other to achieve uniform wear of the radius element and thus better tool utilization.

[0024] The radius piece can have a tongue and groove joint. The tongue or groove can extend over the entire length of the radius piece in the axial direction, preferably over the entire length of the radius piece between its opposing end faces.

[0025] The multi-part design of the bending mandrel or die allows the individual parts, particularly the radius piece and the flat, to be made of different materials, especially materials of varying hardness, depending on the mechanical stresses they are subjected to. While the radius piece is subject to normal wear during bending operations and should therefore have a high hardness, at least on its surface, the flat is designed to hold the radius piece in place and guide it with the bending die. Accordingly, the radius piece can be made of or consist of a first metal, and the flat can be made of or consist of a second metal. The first metal can have a greater hardness than the second metal. The hardness can be determined according to the Rockwell scale (HRC).The first metal can be a hardened tool steel, for example with a hardness of 55-65 HRC, particularly preferably 58-62 HRC. It is preferably case-hardened, preferably with a hardness of 56-58 HRC. The radius piece can be surface-hardened or through-hardened, with the base being unhardened. The second metal can be a tool steel, preferably an unhardened tool steel, for example tool steel 1.2379 or unhardened X155CrVMo12-1. It is preferred that the second metal be an unhardened tool steel, while the first metal is a hardened tool steel, for example with the Rockwell hardness (HRC) specified above. This ensures that, in the event of brittle fracture of the hardened tool steel of the radius piece during bending operations, the amount of material potentially ejected is small.

[0026] A bending device for bending metal profiles, in particular flat rails, is further described, wherein the device comprises an adjustable bending ram which is adjustable with respect to a counter support, as well as a bending prism and a bending mandrel or a bending punch of the type described above. The bending punch can be fixed to the bending ram if the bending prism is supported and / or fixed to the counter support, and wherein the bending mandrel is supported and / or fixed to the counter support if the bending prism is fixed to the bending ram.

[0027] If the bending device has a bending mandrel, its back side, facing away from the radius piece, can rest against the counter-holder of the bending device. The back side of the mandrel thus forms a bearing surface for the counter-holder. Fasteners for attaching the radius piece to the mandrel can be freely accessible on the back side, or bearing surface, for example, a countersunk screw head with a tool recess. To replace the radius piece, the counter-holder can be moved away from the bending mandrel, exposing the back side of the mandrel and thus the accessible fastener for attaching the radius piece. The radius piece can then be replaced with a new one or, if necessary, reattached to the mandrel in a 180° rotated position.

[0028] If the bending device has a bending die, this can be mounted to the bending die of the bending device via a workpiece holder. The tool holder may expose a fastener, accessible from the rear of the workpiece where the bending die rests against the tool holder, by which the radius piece is secured to the workpiece. The workpiece holder may have an opening, such as a slot, for this purpose. To replace the bending die, it is only necessary to detach the radius piece from the workpiece, which can remain attached to the tool holder. The radius piece can then be reattached to the workpiece in a 180° rotated position or replaced with a different radius piece.

[0029] Further details are explained with reference to the figures below. The embodiments shown in the figures have features that, individually or in any combination, can be suitable for realizing embodiments of the invention. These show:

[0030] Figure 1 shows an embodiment of a bending device according to the prior art;

[0031] Figure 2 shows another embodiment of a bending device according to the prior art.

[0032] Figure 3 shows an embodiment of a plot for a bending mandrel in perspective view;

[0033] Figure 4 shows an embodiment of a bending mandrel in perspective view of the radius piece;

[0034] Figure 5 shows the embodiment according to Figure 4 in a perspective view of the rear of the property;

[0035] Figure 6 shows another embodiment of a plot for a bending die in a perspective view of the front;

[0036] Figure 7 shows the embodiment according to Figure 6 in a perspective view of the back; and

[0037] Figure 8 shows a perspective view of a bending die mounted on a tool holder of a bending device. Figure 1 shows an exemplary embodiment of a bending device 100. The bending device 100 has a horizontal support surface for placing metal profiles to be bent, which are to be bent about a vertical axis at a specific position along their length. The metal profiles 200 can be, for example, busbars from switchgear construction, in particular copper busbars and aluminum busbars.

[0038] Such copper rails can have a material thickness of more than 10 mm and a profile width of 10 mm or significantly more. Accordingly, such a flat rail is placed on the support surface with its narrow long side facing upright, so that it can be bent around its wider long side perpendicular to the longitudinal direction.

[0039] As can be seen in the combined view of Figures 1 and 2, essentially two configurations of the bending device are common. In the configuration shown in Figure 1, a bending punch 2 is mounted on a bending ram 102 facing the user, while the bending prism 103 is supported on a counter support 101 opposite the bending ram and the bending punch 2. In the embodiment shown in Figure 2, the bending prism is mounted on the bending ram 102 and a bending mandrel 1 is supported on the counter support 101. For better illustration, the counter support 101 is shown in Figure 2 offset from the bending mandrel 1. In this offset position, the rear side of the bending mandrel 1, facing away from the bending radius, is freely accessible.

[0040] The bending mandrel 1 and the bending punch 2 are subject to wear and must therefore be replaced regularly. To replace the bending mandrel 1, a locking mechanism, such as a screw, located below the table must be loosened. The bending mandrel 1 can then be lifted upwards and replaced with a new one, which must then be screwed back in place in reverse order. Furthermore, the known bending mandrels and bending punches have the disadvantage that they may only be surface-hardened to prevent brittle fractures during operation and under high mechanical stress. Such fractures could lead to flying fragments and injuries to the operator.

[0041] Figures 2 to 5 show an exemplary embodiment of a bending mandrel 1, with the base 5 shown in Figure 3. This base has a support surface 12 on opposite sides for bearing against a counter-holder 101 (compare Figures 1 and 2) and a positive locking 9 for the reliable positioning of a radius piece 4.

[0042] Between the opposing sides, through holes 7 are provided, each opening into a blind hole 8 on the side of the radius piece 4 facing the ground 5. An internal thread is provided in the blind hole 8. Starting from the support surface 12, a screw can be inserted through the through hole 7 into the internal thread in the blind hole 8 of the radius piece 4 to secure the radius piece 4 to the ground 5. As can be seen in Figure 5, the screw connections 6 are countersunk in the through holes 7 so that the support surface 12 is not affected, and in particular, remains a flat surface for secure support against a counter-support 101. The radius piece 4 has a constant cross-section along its axial direction X and is therefore easy to manufacture. It can be placed on the ground in two positions rotated 180° relative to each other, thereby forming a positive connection 9.Accordingly, the fastening means, i.e. the screw connections 6, in particular the through holes 7 and the blind holes 8, are also arranged symmetrically.

[0043] Figures 6 to 8 show a bending die 2, which in turn consists of a flat surface 5 and a radius section 4. Analogous to the embodiment according to Figures 2 to 5, the flat surface 5 and the radius section 4 can be designed as separate components, in particular made of different materials. In particular, the radius section 4 can have a higher hardness than the flat surface 5. For example, the radius section 4 can be hardened, preferably surface-hardened, e.g., case-hardened, but optionally also through-hardened. This provides a considerable advantage over bending dies and bending mandrels according to the prior art, where, for safety reasons, through-hardening of the entire bending mandrel or the entire bending mandrel is not required.

[0044] Bending dies should always be avoided.

[0045] The surface 5 of the bending die 2 can be made of unhardened tool steel. It can be fixed to a tool holder 105 via a T-shaped tongue-and-groove connection. The surface 5 has a through-hole 7 for attaching the radius piece 4. On the rear side of the surface 5, facing away from the tongue-and-groove connection 10, the surface 5 has an elongated hole into which the through-holes 7 open. The tool holder 105 has a further opening 106 through which a tool, such as a screwdriver or Allen key, can be used to access fasteners, such as screws, inserted in the through-holes 7. This allows the bending die 2 to remain attached to the tool holder 105, at least to the extent of its surface 5, for the purpose of replacing the bending radius 4.The features disclosed in the preceding description, in the claims, and in the drawings can be relevant individually and in any combination for the realization of embodiments of the invention, the scope of protection being determined by the claims. List of reference numerals:

[0046] 1 bending mandrel

[0047] 2 bending dies

[0048] 3 Bending radius

[0049] 4 radius pieces

[0050] 5 plot of land

[0051] 6 screw connection

[0052] 7 through holes

[0053] 8 blind hole

[0054] 9 Form closure

[0055] 10 tongue and groove joint

[0056] 11 Front

[0057] 12 support surface

[0058] 100 Device

[0059] 101 Counterholds

[0060] 102 bending rams

[0061] 103 Bending prism

[0062] 104 tie rods

[0063] 105 tool holders

[0064] 106 Breakthrough / Slotted Hole

[0065] 107 Screw channel

[0066] 200 metal profiles

[0067] X Axial direction

Claims

Claims:

1. Bending mandrel (1 ) or bending punch (2) for a device (100) for bending metal profiles (200), in particular flat rails, wherein the bending mandrel (1 ) or bending punch (2) is designed in multiple parts and has a bending radius (3), characterized in that the bending mandrel (1 ) or bending punch (2) has a radius piece (4) having the bending radius (3) and a surface (5) on which the radius piece (4) is detachably mounted.

2. Bending mandrel (1 ) or bending punch (2) according to claim 1, wherein the radius piece (4) is fixed to the surface (5) by means of at least one releasable screw connection (6).

3. Bending mandrel (1 ) or bending die (2) according to claim 1 or 2, wherein the surface (5) has at least one through hole (7) and the radius piece (4) has at least one blind hole (8) aligned with the through hole (7) and having an internal thread.

4. Bending mandrel (1 ) or bending punch (2), in particular bending mandrel (1 ), according to claim 3, wherein the through-hole (7) extends between a support surface (12) for supporting the bending mandrel (1) on a counter support (101) of a device (100) for bending metal profiles and a side of the bending mandrel (1) opposite the support surface (12), in particular a positive locking (9) on the opposite side.

5. Bending mandrel (1 ) or bending die (2) according to one of the preceding claims, wherein the radius piece (4) rests on the surface (5) on a side facing away from the bending radius (3) via at least one positive locking (9).

6. Bending mandrel (1) or bending die (2) according to one of the preceding claims, wherein the radius piece (4) is connected to the surface (5) on a side facing away from the bending radius (3) via at least one tongue and groove joint (10), preferably via a rectangular or an undercut tongue and groove joint (10), particularly preferably a wedge-shaped tongue and groove joint (10), a round profile tongue and groove joint (10), a dovetail tongue and groove joint (10), or a T-shaped tongue and groove joint (10).

7. Bending mandrel (1 ) or bending die (2) according to claim 6, wherein the surface (5) has at least one through hole (7) and the radius piece (4) has at least one blind hole (8) aligned with the through hole (7) and having an internal thread, wherein the through hole (7) and the blind hole (8) each open into one of the tongue and groove of the tongue-and-groove connection (10).

8. Bending mandrel (1) or bending die (2) according to claim 6 or 7, wherein the groove and tongue of the tongue-and-groove connection (10) are formed continuously along the longitudinal direction of the tongue-and-groove connection (10) over the entire dimension of the surface (5) and radius piece (4) on the opposite sides of the surface (5) and radius piece (4), preferably as a sliding tongue-and-groove connection (10), so that the radius piece (4) and the surface (5) can be pushed onto the surface (5) along the tongue-and-groove connection (10).

9. Bending mandrel (1 ) or bending punch (2) according to one of the preceding claims, wherein the radius piece (4) has a constant cross-section in the axial direction of the bending radius (3), preferably over the entire length of the radius piece (4) in the axial direction, particularly preferably over the entire length of the radius piece (4) between its opposite end faces (11 ).

10. Bending mandrel (1) or bending die (2) according to claim 9, wherein the radius piece (4) has a tongue and groove joint (10) extending over the entire length of the radius piece (4) in the axial direction, preferably over the entire length of the radius piece (4) between its opposite end faces (11).

11. Bending mandrel (1) or bending die (2) according to any of the preceding claims, wherein the radius piece (4) comprises or consists of a first metal and the face (5) comprises or consists of a second metal, wherein the first metal has a greater Rockwell hardness (HRC) than the second metal.

12. Bending mandrel (1) or bending punch (2) according to claim 11, wherein the first metal is a hardened tool steel, preferably with a hardness of 55-65 HRC, particularly preferably case-hardened with a hardness of 56-58 HRC.

13. Bending mandrel (1) or bending punch (2) according to claim 11 or 12, wherein the radius piece (4) is hardened, preferably surface hardened, particularly preferably case hardened with a hardness of 56-58 HRC, wherein the surface (5) is preferably unhardened.

14. Bending mandrel (1) or bending punch (2) according to one of claims 11 to 13, wherein the second metal is a tool steel, preferably an unhardened tool steel, particularly preferably tool steel 1.2379 or X155CrVMo12-1 unhardened.

15. Device (100) for bending metal profiles (200), in particular flat rails, wherein the device (100) comprises an adjustable bending plunger (102) which is adjustable with respect to a counter support (101), as well as a bending prism (103) and a bending mandrel (1) or a bending punch (2) according to one of the preceding claims, wherein the bending punch (2) is fixed to the bending plunger (102) when the bending prism (103) is supported on the counter support (101), and wherein the bending mandrel (1) is supported on the counter support (101) when the bending prism (102) is fixed to the bending plunger.

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