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Title:
DIE FOR BENDING SHEET METAL, USE OF SUCH A DIE, SYSTEM COMPRISING SUCH A DIE AND METHOD OF BENDING SHEET METAL
Document Type and Number:
WIPO Patent Application WO/2020/071989
Kind Code:
A1
Abstract:
This document discloses a die (10) for bending sheet metal (2, 2'), comprising a die body (100a, 100b) and a groove (101, 101a, 101 b) formed in the die body. The die has a slot (102, 102a, 102b) extending across the groove in such a way that a piece of sheet metal located in the groove is visible through the die body (100a, 100b). The document discloses a system comprising the die, use of the die for bending sheet metal and a method of bending sheet metal.

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Inventors:
STARK ANDREAS (SE)
LINDBERG CLAS (SE)
Application Number:
PCT/SE2019/050957
Publication Date:
April 09, 2020
Filing Date:
October 03, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
VAEDERSTAD HOLDING AB (SE)
International Classes:
B21D5/02; B21D5/00
Foreign References:
JP2001018011A2001-01-23
JP2013116480A2013-06-13
JP2001058213A2001-03-06
GB2238265A1991-05-29
US6553803B12003-04-29
Attorney, Agent or Firm:
AWA SWEDEN AB (SE)
Download PDF:
Claims:
CLAIMS

1. Die (10) for bending sheet metal (2, 2'), comprising a die body (100a, 100b) and a groove (101 , 101 a, 101 b) formed in the die body,

characterized by

a slot (102, 102a, 102b) extending across the groove in such a way that a piece of sheet metal located in the groove is visible through the die body (100a, 100b).

2. Die according to Claim 1 , the slot being formed in such a way that a side of the piece of sheet metal facing the die is visible through the die body.

3. Die according to either Claim 1 or 2, the groove having a base and the slot having slot portions (102a, 102b) on both sides of said base, in such a way that two shanks (S1 , S2) of the piece of sheet metal (2') separated by a bending angle (V) are visible.

4. Die according to any one of the preceding claims, the slot extending through the entire die in such a way that the die comprises two separate die body portions (100a, 100b).

5. Die according to any one of Claims 1 -3, the slot (102a, 102b) only partly extending across the die in such a way that the die body portions (100a, 100b) are connected by at least one material bridge (103).

6. Die according to any one of the preceding claims, the groove having a longitudinal direction (Z), the slot having an extension in the longitudinal direction corresponding to 0.5-20 mm, preferably 1 -15 mm or 1 -5 mm.

7. Die according to Claim 6, the slot having an intersection area together with the groove, the intersection area, viewed perpendicularly to the longitudinal direction (Z), having an extension corresponding to at least 20% of a depth of the groove, preferably at least 50% of said depth.

8. Use of a die according to any one of the preceding claims for bending a piece of sheet metal having a thickness between 5 and 25 mm, preferably between 5 and 20 mm, between 7 and 15 mm or between 10 and 15 mm.

9. Use of a die according to any one of Claims 1 -7 for bending a piece of sheet metal (2) in order to provide a piece of sheet metal (2') bent accordingly, which has a first shank (S1 ) and a second shank (S2), where at least one of the shanks has a length, calculated from a bending angle (V), that is less than 150% of a distance between a base of the groove and an outer edge of the die, viewed in a direction parallel to the orientation of the piece of sheet metal just before the bending operation and perpendicular to the longitudinal direction of the groove, said length preferably being less than 100% of said distance or less than 70% of said distance.

10. System for bending sheet metal, comprising:

a die (10) according to any one of the preceding claims,

a bending knife (1 1 ), extending parallel to the groove (102, 102a, 102b) and being movable relative to the die in order to bend the piece of sheet metal by interacting with the groove, and

at least one measuring device (12a, 12b), arranged to determine, through the slot (102, 102a, 102b), an orientation of a sheet metal shank (S1 , S2).

11. System according to Claim 10, the system comprising a first measuring device (12a) arranged to determine an orientation of a first sheet metal shank (S1 ), and a second measuring device (12b), arranged to determine an orientation of a second sheet metal shank (S2), the sheet metal shanks (S1 , S2) being separated by a bending angle (V).

12. Method of bending a piece of sheet metal (2), comprising:

arranging the piece of sheet metal (2) relative to a groove (101 , 101 a,

101 b) of a bending die (10) in such a way that a first portion of the piece of sheet metal is located on a first side of a longitudinal centre line of the groove and a second portion of the piece of sheet metal is located on a second, opposite, side of the centre line, and

with the aid of a bending knife (1 1 ), carrying out a bending operation in such a way that said first and second portions of the piece of sheet metal form respective shanks (S1 , S2) of a piece of sheet metal (2') bent

accordingly,

characterized by

determining, with the aid of a measuring device (12a, 12b), an orientation of at least one of the shanks (S1 , S2) through at least one slot (102, 102a, 102b) in the bending die.

13. Method according to Claim 12, further comprising determining, based on said orientation, a reciprocal angle between the shanks (S1 , S2).

14. Method according to either Claim 12 or 13, the orientation of both shanks (S1 , S2) being determined through said at least one slot.

15. Method according to any one of Claims 12-14, the bending die being arranged in such a way that the piece of sheet metal is positioned vertically above the bending die and the measuring device being positioned vertically under the bending die.

16. Method according to any one of Claims 12-14, the method comprising, during the bending of the piece of sheet metal (2):

determining a first orientation of at least one of the shanks, then moving the bending knife and the die relative to each other, and then determining a second orientation of said at least one of the shanks.

Description:
DIE FOR BENDING SHEET METAL, USE OF SUCH A DIE, SYSTEM COMPRISING SUCH A DIE AND METHOD OF BENDING SHEET METAL

Technical Field

This document discloses a die for bending sheet metal, a system comprising such a die and a method of bending sheet metal, which can be used in particular when bending sheet metal having a thickness exceeding 5 mm, such as when bending sheet metal having a thickness of 5-20 mm, especially 8-15 mm.

Background

When bending sheet metal, it is known to utilize a die with a groove and a tool, defined as a“knife”, which, as a result of a relative movement between the die and the knife, interacts with the groove so as to bend the piece of sheet metal in such a way that the piece of sheet metal comes to have a pair of shanks that are separated by an angle.

Viewed in cross section, the groove of the die can generally be V- shaped, with a pair of walls or other support surfaces separated by a base. The walls form an angle corresponding to a maximum bending yield, apart from the possibility of spring-back.

The knife can also have a point, which, when viewed in cross section, is generally V-shaped.

The groove and the knife can have angles exceeding a maximum bending angle intended for the system. Instead, a true bending angle can be controlled by measuring the angle between the sheet metal shanks and bringing the knife and the die together sufficiently to provide the desired bending angle.

Such measuring can be carried out continuously and most often with the aid of a line laser, which applies the respective lines on each shank of the piece of sheet metal perpendicular to the groove and reads the line with the aid of a camera or another sensor. The method above functions excellently when bending thinner pieces of sheet metal and when bending pieces of sheet metal where the length of the shanks, viewed from the angle, is sufficiently long.

When bending very thick pieces of sheet metal and when bending short shanks, it is not possible to utilize the measurement since the die conceals the field of vision of the measuring device toward the shanks.

Summary

One object is thus to fully or partly eliminate the above problems when measuring the angle between the sheet metal shanks during the process of bending sheet metal.

The invention is defined by the attached independent patent claims. Embodiments are set forth in the dependent patent claims, in the description that follows and in the drawings.

According to a first aspect, a die is provided for bending sheet metal, comprising a die body and a groove formed in the die body. The die has a slot extending across the groove in such a way that a piece of sheet metal located in the groove is visible without being concealed by the die body.

“Across” means that the slot intersects the groove in the longitudinal direction, for example with an angle between 30 and 90 degrees, preferably between 45 and 90 degrees or approximately 90 degrees.

Normally, a die for bending sheet metal is placed with the groove facing upward and a bending knife is movable in a substantially vertical direction. Measuring devices can thus be placed underneath, or obliquely underneath, the die for bending sheet metal and, by virtue of the slot, a clear view toward the bent sheet metal shanks is still achieved.

The slot can be formed in such a way that a side of the piece of sheet metal facing the die is visible through the die body.

The groove can have a base and the slot can have slot portions on both sides of said base, in such a way that two shanks of the piece of sheet metal separated by a bending angle are visible without being concealed by the die body. The slot can extend through the entire die in such a way that the die comprises two separate die body portions.

The slot can only partly extend across the die in such a way that the die body portions are connected by at least one material bridge.

A material bridge can be located at the base of the groove.

Alternatively, or as a complement, one or more material bridges can be located at one, two or more outer corners of the cross section.

The groove can have a longitudinal direction, the slot having an extension in the longitudinal direction corresponding to 0.5-20 mm, preferably 1 -15 mm or 1 -5 mm.

The slot can have an intersection area together with the groove, the intersection area, viewed perpendicularly to the longitudinal direction, having an extension corresponding to at least 20% of a depth of the groove, preferably at least 50% of said depth.

According to a second aspect, the use of a die as described above is provided for bending a piece of sheet metal having a thickness between 5 and 25 mm, preferably between 5 and 20 mm, between 7 and 15 mm or between 10 and 15 mm.

According to a third aspect, the use of a die as described above is provided for bending a piece of sheet metal in order to provide a piece of sheet metal bent accordingly, which has a first shank and a second shank, where at least one of the shanks has a length, calculated from a bending angle, that is less than 150% of a distance between a base of the groove and an outer edge of the die, viewed in a direction parallel to the orientation of the piece of sheet metal just before the bending operation and perpendicular to the longitudinal direction of the groove, said length preferably being less than 100% of said distance or less than 70% of said distance.

The distance is typically a horizontal distance.

The use according to the second and the third aspects can be combined.

According to a fourth aspect, a system for bending sheet metal is provided, comprising a die as described above, a bending knife, extending parallel to the groove and being movable relative to the die in order to bend the piece of sheet metal by interacting with the groove, and at least one measuring device, arranged to determine, through the slot, an orientation of a sheet metal shank.

The system can comprise a first measuring device, arranged to determine an orientation of a first sheet metal shank, and a second

measuring device, arranged to determine an orientation of a second sheet metal shank, the sheet metal shanks being separated by a bending angle.

According to a fifth aspect, a method of bending a piece of sheet metal is provided, comprising arranging the piece of sheet metal relative to a groove of a bending die in such a way that a first portion of the piece of sheet metal is located on a first side of a longitudinal centre line of the groove and a second portion of the piece of sheet metal is located on a second, opposite side of the centre line, and with the aid of a bending knife, carrying out a bending operation in such a way that said first and second portions of the piece of sheet metal form respective shanks of a piece of sheet metal bent

accordingly. The method comprises determining, with the aid of a measuring device, an orientation of at least one of the shanks through at least one slot in the bending die.

The method can further comprise determining, based on said orientation, a reciprocal angle between the shanks.

The orientation of both shanks can be determined through said at least one slot.

The bending die can be arranged in such a way that the piece of sheet metal is positioned vertically above the bending die and the measuring device is positioned vertically under the bending die.

The method can comprise, during the bending of the piece of sheet metal, determining a first orientation of at least one of the shanks, then moving the bending knife and the die relative to each other, and then determining a second orientation of said at least one of the shanks.

Measuring the orientation of the shanks and, based thereon, determining the reciprocal angle of the shanks can thus occur a number of times during one and the same bending operation. For example, measuring and determining can occur substantially continuously during the bending operation. Measuring and determining can both occur during a first part of the bending operation, in which the knife moves toward the die, and during a second part of the bending operation, in which the knife moves away from the die.

As a result, by means of the measurement it is possible to determine whether spring-back is present and, based thereon, determine to drive the knife once more toward the die in order to compensate for such spring-back.

Brief description of the drawings

Fig. 1 shows a system for bending sheet metal before a bending operation.

Fig. 2 shows the system for bending sheet metal when a bending operation is completed.

Fig. 3 shows a first embodiment of a die for bending sheet metal.

Fig. 4 shows a second embodiment of a die for bending sheet metal.

Detailed description

A system for bending sheet metal will be described below with reference to the accompanying drawings.

Figs 1 and 2 show a system 1 for bending sheet metal comprising a bending die 10, a bending knife 1 1 and a pair of measuring devices 12a, 12b.

The bending die 10 comprises a die body 100a, 100b, which can be formed from metal or ceramic material of sufficient hardness and toughness in order to be able to withstand the forces that the die is subjected to.

Furthermore, the die 10 has a groove 101 , 101 a, 101 b, which can have a cross section (viewed in the X-Y plane) substantially forming a V, a U, or similar shape, and a longitudinal direction Z. The cross section of the groove 101 , 101 a, 101 b can be substantially constant along its longitudinal direction Z. The groove 101 , 101 a, 101 b can have, but does not have to have, groove walls that are continuous, viewed in the transverse direction of the groove.

The walls of the groove 101 , 101 a, 101 b form support surfaces, determining a maximum bending angle.

The bending knife 1 1 is movable relative to the die 10 in a direction which enables it to project down into the groove 101 , 101 a, 101 b and thereby bending the piece of sheet metal 2 through interaction between the groove and the knife.

A resulting bending angle V can depend on how deep into the groove the knife 1 1 is brought.

The die 10 has a slot extending across the longitudinal direction Z of the die. Through the slot, the side of the piece of sheet metal 2, 2' facing the die is visible for one or more measuring devices 12a, 12b. More specifically, both shanks S1 , S2 of the bent piece of sheet metal 2’ can be visible for the measuring device 12a, 12b, in such a way that the reciprocal angle of the shanks can be measured by the measuring device.

The measuring device can comprise one or more measuring devices. Through the slot 102, 102a, 102b, a measuring device 12a, 12b can provide a laser line or other suitable light pattern on the shank S1 , S2. A camera or other light sensor can read the light pattern and, in a manner known per se, determine the orientation of the shank relative to the measuring device and thus also calculate the reciprocal angle of the shanks S1 , S2.

The measuring device can comprise two measuring devices each generating a respective laser line or light pattern, or one measuring device generating a single laser line or a light pattern applied to both shanks.

Furthermore, the measuring device can comprise two cameras or light sensors, each reading light from one of the shanks S1 , S2, or one camera or light sensor reading light from both of the shanks S1 , S2.

With reference to Fig. 3, the die 10 can be formed by substantially one piece of material and with at least two die portions 100a, 100b, connected by at least one material bridge 103. Such a die 10 can comprise one, two or more slots or slot portions 102a, 102b.

With reference to Fig. 4, the die 10 can be formed by two or more separate die portions 100a, 100b, a single slot 102 being formed between the die portions. The die portions 100a, 100b can thereby be held in position by a common die holder (not shown).

The slot 102, 102a, 102b can have a width, viewed in the longitudinal direction of the groove Z, of 0.5-30 mm, preferably 1 -25 mm or 5-15 mm. It will be appreciated that a narrower slot reduces the risk of undesired embossing of the bent piece of sheet metal.

The die can have a plurality of slots 102 or sets 102a, 102b of slots, which are separated in the longitudinal direction Z of the groove, in such a way that measuring at a plurality of positions along the groove is enabled. A plurality of measuring devices can be used during such measuring.

Alternatively, a measuring device can be displaceable along the groove for measuring at different positions. It is possible to provide a measuring device with the ability to automatically detect the instance of a slot.

Normally, a die 10 for bending sheet metal is placed with the groove 101 , 101 a, 101 b facing upward and the bending knife 1 1 is movable in a substantially vertical direction Y. The measuring devices can thus be placed underneath, or obliquely underneath, the die 10 for bending sheet metal and, by virtue of the slot, a clear view toward the sheet metal shanks is still achieved.

The die, system and method described above can be applied for cold bending as well as warm bending of sheet metal.