CN112105560B

CN112105560B - Strapping apparatus and method for securing a metal strap around one or more articles

Info

Publication number: CN112105560B
Application number: CN201980031404.8A
Authority: CN
Inventors: 艾瑞克·丹尼尔森; 彼得·马斯勒德特; 乌鲁夫·库斯特姆
Original assignee: Sweden Senders Co ltd
Current assignee: Sweden Senders Co ltd
Priority date: 2018-05-11
Filing date: 2019-05-09
Publication date: 2022-08-02
Anticipated expiration: 2039-05-09
Also published as: WO2019215282A1; EP3566957B1; CN112105560A; TW201946839A; US20210237917A1; EP3566957A1; JP2021523066A

Abstract

A strapping machine, comprising: a feeding device for feeding a metal belt (3) around one or more objects and subsequently retracting the belt to tension the belt around the objects; a welding device for forming a welded joint between a first portion at the leading end of the metal strip and an overlapping second portion at the trailing end of a length of metal strip (3a) fed around the articles, thereby securing the length of metal strip around the articles; a support member (24) for supporting the overlapping strap portions during formation of the joint, a recess (25) being provided in an upper support surface (26) of the support member; and a punch element (27) having a shape adapted to the shape of the recess, the punch element and the support member being arranged to form a permanent protrusion (30) on the first metal strip part by a punch forming action between the punch element and the support member.

Description

Strapping apparatus and method for securing a metal strap around one or more articles

Technical Field

The invention relates to a strapping apparatus according to the preamble of claim 1. The invention relates to a method according to claim 9 for fixing a length of metal strip in a loop around one or more objects.

Background

Many different configurations of automatic strapping machines are known for applying a metal strap in a loop around an article or a stack of articles, tensioning the metal strap around the article/stack of articles, and then joining overlapping portions of the metal strap to secure the metal strap around the article/stack of articles. WO 2017/129679 a1 discloses a strapping apparatus in which a welding device is used to form a welded joint between overlapping portions of a metal strap to secure the metal strap in a loop around an article or a stack of articles. This known strapping machine comprises a clamping device for clamping and locking a first strap part at the front end of the strap after applying a length of the strap in a loop around the article/stack of articles and before retracting the strap to tighten it around the article/stack of articles, wherein the clamping device is configured to grip the strap at an area where the strap will be subjected to tensile stress when the strap has been released from the strapping machine, which constitutes a part of a final strap loop on the article/stack of articles. This is the standard clamping position for a clamping device of a strapping apparatus for strapping an object or a stack of objects with a band of metallic material.

Disclosure of Invention

The object of the present invention is to achieve a new and advantageous strapping machine of the above-mentioned type.

According to the invention, this object is achieved by a strapping apparatus having the features of claim 1.

The binding machine of the present invention comprises:

a welding device for forming a weld joint between a first strip portion at a leading end of a length of metal strip arranged in a loop around one or more articles to be strapped and an overlapping second strip portion at a trailing end of the length of metal strip to secure the length of metal strip in a loop around the one or more articles;

a bundling unit including a support member for supporting the overlapped first and second metal strap portions during forming of the weld joint, wherein a recess is provided in an upper support surface of the support member; and

a feeding device for feeding the metal strap through the strapping unit, looping around an article receiving space configured for receiving one or more articles to be strapped, then returning into the strapping unit, and then retracting the metal strap to tension the metal strap around the one or more articles received in the article receiving space.

According to the invention, the strapping unit comprises a stamped element having a shape adapted to the shape of the recess in the support member so as to allow the stamped element to be accommodated in the recess). The strapping unit further comprises an actuating device configured to move the punch element and the support member relative to each other between a first mutual position, in which, the punch element is located at a distance from the recess in the support member, while in the second mutual position, the punch element is accommodated in the recess, wherein the stamping element and the support member are configured such that when the stamping element and the support member are moved relative to each other from the first mutual position to the second mutual position by the actuating means and a portion of the first metal strap portion is accommodated in the space between the stamping element and the support member, a permanent projection is formed on the first metal strip portion at a location between the leading end of the length of metal strip and the weld joint by a press forming action between the punch element and the support member.

As long as the punch element and the support member are kept in the above-mentioned second mutual position, the permanent protrusion formed on the first metal strap part will, together with the recess in the punch element and the support member, ensure that the first metal strap part is locked to the strapping unit with a positive locking effect, preventing it from sliding in the longitudinal direction of the metal strap when the feed device retracts the metal strap and tightens the metal strap against the article or stack of articles to be strapped. In this way, the front end of the metal strip is locked to the strapping unit in an efficient and reliable manner. Furthermore, the projection formed on the first metal strap portion is located between the front end of the metal strap and the weld joint between the first and second metal strap portions, i.e. a portion which is not subjected to any tensile stress when the length of metal strap has been released from the strapping unit. Thus, the weakening deformation caused by the stamping element and the support member at the raised area on the length of metal strip will not have any negative effect on the strength of the loop formed by the length of metal strip, compared to the aforementioned standard case when the metal strip is clamped and subjected to weakening deformation on the opposite side of the weld joint, i.e. on the portion of the length of metal strip that is subjected to tensile stress when the length of metal strip has been released from the strapping unit. In said previously known case, the weakening deformation on the length of metal strip caused by the clamping of the first metal strip portion can have a negative effect on the strength of the loop formed by the length of metal strip.

When the length of metal strip has been released from the strapping unit, the projection formed by the stamping element on the length of metal strip is pressed against the outer surface of the item/stack of items and acts as a spacer between the item/stack of items and the loop formed by the length of metal strip. Thereby, the protrusion will contribute to increasing the tension of the loop, thereby improving the strapping effect. When the length of metal strip is to be removed from the item/stack of items, the gap formed by the projection between the ring and the outer surface of the item/stack of items will also contribute to the cutting of the ring with respect to the subsequent unbinding operation.

Further advantageous features of the strapping apparatus according to the invention will appear from the following description and the dependent claims.

The invention relates to a method having the features of claim 9.

Further advantageous features of the method according to the invention will appear from the following description and the appended claims.

Drawings

The following is a detailed description of embodiments of the invention, which are cited as examples, with reference to the accompanying drawings. In the context of the drawings, it is,

FIG. 1 is a general view of a strapping machine in accordance with one embodiment of the present invention;

FIGS. 2 a-2 i are partial cross-sectional overviews of components included in the strapping machine of FIG. 1, as seen at various stages during a process of securing a length of metal strap in a loop around a stack of articles;

figure 3 is a schematic view of a support member and a punch element included in the strapping machine of figure 1, wherein the punch element is located at a distance from an associated recess in the support member in a retracted position;

FIG. 4 is a schematic view of the support member and the punch element, wherein the punch element is received in the recess of the support member in an advanced position;

FIG. 5 is a schematic side view of a length of metal strip secured around a stack of articles;

FIG. 6 is a top plan view of a section of metal strip of FIG. 5;

FIG. 7 is a top plan view of a portion of the metal strap being secured around one or more articles to be strapped illustrating the heated area on the metal strap prior to releasing the loop from the remainder of the metal strap;

FIG. 8 is a plan view corresponding to FIG. 7 when the belt loop is released from the remainder of the metal belt;

fig. 9 is a section according to the line IX-IX in fig. 8;

FIG. 10 is a top plan view of a portion of the metal strap being secured around one or more articles to be strapped illustrating the break lines on the metal strap prior to releasing the strap loop from the remainder of the metal strap;

FIG. 11 is a cross-section according to line XI-XI in FIG. 10;

FIG. 12 is a top plan view of a portion of the metal strap being secured around one or more articles to be strapped illustrating another type of break line on the metal strap prior to releasing the strap loop from the remainder of the metal strap; and

fig. 13 is a cross section according to line XIII-XIII in fig. 12.

Detailed Description

Some of the components comprised in a strapping machine 1 according to an embodiment of the invention are illustrated very schematically in fig. 1. The binding machine 1 includes:

a guide rail 2 for guiding an elongated strip 3 of metal material around a space 4, the space 4 being configured for accommodating one or more objects 10 to be bundled;

a bundling unit 20 for securing the elongate strap 3 around the one or more articles 10;

a feeding device 5 for feeding the elongated strip 3 from a supply coil 6 via the bundling unit 20 into the guide rail 2, looping around the article receiving space 4 along the guide rail and then back into the bundling unit 20, and then retracting the elongated strip 3 to tension the elongated strip 3 around the one or more articles 10 received in the space 4; and

an accumulator 9 for temporarily accumulating a portion of the elongated strip 3 when the feeding device 5 retracts the binding element and then releasing the accumulated portion of the elongated strip when the feeding device 5 feeds the elongated strip forward.

The guide rail 2 may, for example, have the form of a rail with a longitudinal opening facing the article receiving space 4. As an alternative, the elongate strip may also be fed in a loop around the article or articles to be bundled without the use of any guide rails. This may be achieved by feeding the elongate strip through a bending device configured to bend the elongate strip in the following manner: it will move without contact with any guide rails or the like in a free space in a substantially circular path around the article or articles 10 to be strapped, wherein a funnel-shaped guide element may be arranged at the end of the path in order to catch the front end of the elongated strap and guide it into the strapping unit.

The article or articles 10 to be bundled can be positioned in the article receiving space 4 before, during or after the elongated strip 3 is fed in one turn around the space 4.

As an alternative to using an accumulator 9, slackening of the elongate tape 3 when the feeding device 5 retracts the elongate tape can be taken up or avoided by rotating the feeding tape roll 6 in the opposite direction.

In the embodiment described, the feed device 5 comprises two

rotatable feed rollers

5a, 5b positioned opposite each other and configured to contact opposite sides of a portion of the elongated strip 3 received in the nip between the feed rollers. At least one of the

feed rollers

5a, 5b is rotationally driven by an actuator (not shown) in the form of a reversible drive motor to move the elongate strip 3 in its longitudinal direction. The drive motor is preferably an electric motor, but as an alternative it may be a hydraulic motor or a pneumatic motor. The feeding device 5 may also comprise any other suitable type of actuator for feeding and retracting the elongated strip 3.

Some of the components comprised in the above described strapping unit 20 are very schematically illustrated in fig. 2 a-2 i. The binding unit 20 comprises a welding device 21 (see fig. 2a) for forming a welded joint 8 (see fig. 2h and 2i) between a first strip portion 7a at the front end of a length of metal strip 3a arranged around one turn of one or more articles 10 to be bound and an overlapping second strip portion 7b at the rear end of the length of metal strip 3a, so as to secure the length of metal strip 3a around the one or more articles 10. The welding device 21 is configured to form the weld joint 8 as a lap joint, wherein the second metal strap portion 7b overlaps the first metal strap portion 7 a.

The welding device 21 may be any suitable type of welding device. In the embodiment described, the welding device 21 is provided with a laser welding device of a laser welding head 22, wherein the weld joint 8 between the first and second

metal strip portions

7a, 7b is formed by a laser beam 23 (see fig. 2g) emitted from the laser welding head. The welding device 21 includes a mechanism for directing and focusing the emitted laser beam 23 onto a desired target area.

The strapping unit 20 further comprises a support member 24 for supporting the overlapping first and

second strap portions

7a, 7b during the formation of the welded joint 8. The support member 24 is arranged to be located between the first strap part 7a and the outer surface of the article or articles 10 to be strapped during the formation of the weld joint 8. A recess 25 is provided in an upper support surface 26 on the support member 24. When the weld joint 8 has been formed, the support member 24 is moved laterally out of the area between the bundled article(s) 10 and the loop 11 (see fig. 2h and 2i) formed around the article(s), thus releasing the loop from the bundling unit 20.

In the example illustrated in fig. 7-12, the weld joint 8 has an oval shape as seen in plan view. However, the welded joint 8 between the overlapping binding

element portions

7a, 7b can of course also have any other suitable configuration.

The strapping unit 20 also comprises a stamping element 27, the stamping element 27 having a shape adapted to the shape of the recess 25 in the support member 24 so as to allow the stamping element 27 to be received in the recess 25. The punch element 27 has an upper surface 28, as shown in fig. 2a, which upper surface 28 is flush, or at least substantially flush, with the upper support surface 26 on the support member 24 when the punch element 27 is received in the recess 25 in the support member.

An actuating device 29 (very schematically illustrated in fig. 1) comprised in the strapping unit 20 is configured to move the punch element 27 and the support member 24 relative to each other between a first mutual position (see fig. 2c, 2d and 3), in which the punch element 27 is located outside and at a distance from the recess 25 in the support member 24, and a second mutual position (see fig. 2a, 2b, 2 e-2 h and 4), in which the punch element 27 is accommodated in the recess 25. The stamping element 27 and the support member 24 are configured such that when the stamping element 27 and the support member 24 are moved relative to each other from the first mutual position to the second mutual position by the actuating device 29 and a portion of the first metal strip portion 7a is accommodated in the space between the stamping element 27 and the support member 24, a permanent protrusion 30 is formed on the first metal strip portion 7a by a stamping forming action between the stamping element 27 and the support member 24 (see fig. 2 e-2 i, 4, 5 and 9), wherein the protrusion 30 is formed at a position between the front end 12 of the length of metal strip 3a and the weld joint 8 to be formed by the welding device 21.

In the embodiment shown in fig. 2 a-2 i, the actuating means 29 is configured to effect the relative movement between the punch element 27 and the support member 24 by moving the punch element 27 relative to the support member 24. In this case, the punch element 27 is moved downwards towards the support member 24 in order to effect a movement from the first mutual position to the second mutual position, and is moved upwards away from the support member 24 in order to effect a movement from the second mutual position to the first mutual position, wherein the support member 24 is held in a fixed position during the movement of the punch element 27. As an alternative, the actuating device 29 may be configured to effect the relative movement between the punch element 27 and the support member 24 by moving the support member 24 relative to the punch element 27 or by moving the punch element 27 and the support element 24 relative to each other.

When the first and

second strap parts

7a, 7b have been fixed to each other by the welding device 21 and the strap loop 11 thus formed is to be released from the strapping unit 20, the punch element 27 is also horizontally movable by the actuating device 29 so as to allow the punch element to be moved laterally away from the projection 30. According to a first alternative, the punch element 27 is formed as a one-piece element and can be removed from the projection 30 by displacement in the horizontal direction. According to another alternative, the punch element 27 is divided into two portions which are positioned opposite each other and can be removed from the protrusion 30 by being laterally displaced in mutually opposite directions.

The support member 24 may comprise first and second support jaws positioned relative to each other in the manner shown in WO 2017/129679 a1, wherein the support jaws are movable relative to each other between an advanced support position, in which the support jaws constitute a support for the first metal strap portion 7a, and a retracted release position, in which the support jaws are retracted relative to each other so as to allow the first and second

metal strap portions

7a, 7b to pass through the gap between the support jaws after having been joined to each other. Each support jaw may be secured to a pivot arm that is in turn pivotally mounted to the housing 36 of the strapping unit 20. Thus, in this case, the supporting claws can be pivoted between the supporting position and the releasing position. As an alternative, the support claws may be linearly movable between the support position and the release position. The support jaws can be moved between the support position and the release position by the actuating device 29. As an alternative, the support member 24 is formed as a one-piece member and is movable between the support position and the release position by displacement in a horizontal direction.

The actuating means 29 may be electrically, pneumatically or hydraulically driven and may comprise one or more electrically, pneumatically or hydraulically driven actuators.

The strapping unit 20 shown in fig. 2 a-2 i comprises a pressing device 34 for pressing the second metal strap portion 7b against the first metal strap portion 7a with the second metal strap portion 7b overlapping the first metal strap portion 7a, wherein the pressing device 34 is arranged to keep the second metal strap portion 7b pressed against the first metal strap portion 7a during the moment the weld joint 8 between the first and second

metal strap portions

7a, 7b is formed by the welding device 21. In the example shown, the pressing device 34 comprises a pressing member 35, the pressing member 35 being configured to cooperate with the supporting member 24 and being movably mounted to a housing 36 of the strapping unit 20. The first and

second strap parts

7a, 7b are receivable in the space between the pressing member 35 and the support member 24, and the pressing member 35 is movable relative to the support member 24 between a retracted first position (see fig. 2 a-2 f, 2i and 3), in which the pressing member 35 is retracted from the support member 24, and an advanced second position (see fig. 2g, 2h and 4), in which the pressing member 35 presses against the support member 24 to press the first and

second strap parts

7a, 7b together. The pressing member 35 is provided with a passage 37; when the pressing member 35 is in the second position and the first and

second strip parts

7a, 7b are held pressed together between the pressing member 35 and the support member 24, the laser beam 23 from the laser welding head 22 of the welding device 21 may be directed via the channel 37 to an area on the second strip part 7b to form the weld joint 8 between the first and

second strip parts

7a, 7 b. The pressing member 35 is movable between the first and second positions by means of an actuator (not shown), which may be electrically, pneumatically or hydraulically driven. The actuator is advantageously a hydraulic cylinder.

In addition to the design shown in fig. 2 a-2 i, the support member 24, the punch element 27 and the pressing device 34 can of course also have any other suitable design.

The strapping machine 1 further comprises an electronic control device 60 (very schematically illustrated in fig. 1) for controlling the operation of the strapping machine. The electronic control device 60 is connected to the welding device 21 and is configured to control the welding device to direct and focus the laser beam 23 of the welding device onto a desired portion of the elongated strip 3. The electronic control device 60 is also connected to and configured to control the operation of the actuators of the feeding device 5, the actuating device 29 and the pressing device 34.

The electronic control means 60 are configured to control the feeding means 5 to stop the feeding of the elongated strip 3 when the front end 12 of the elongated strip has passed over the notch 25 in the support member from the first end 25a (see fig. 3) of the recess to its opposite second end 25b during its second pass over the support member 24 and has reached a final position beyond the second end 25b of the recess. The punch element 27 and the support member 24 are then moved relative to each other by a downward vertical movement of the punch element 27 and/or an upward vertical movement of the support member 24 until the punch element 27 has been received in the recess 25 and a permanent protrusion 30 has been formed on the first strip part 7 a. The elongate strap 3 is then retracted so as to be tightened around the one or more objects 10 located in the object receiving space 4 of the strapping unit 20, wherein a portion 15 (see fig. 4) of the second strap part 7b is pressed against the upper support surface 26 of the support member 24 under the influence of the tensile force of the elongate strap 3 and abuts against a portion 16 of the first strap part 7a located between the second end 25b of the recess 25 in the support member and the front end 12 of the elongate strap. Thus, during tightening of the elongated strap 3, the portion 16 of the first strap part 7a is clamped between the support member 24 and the second strap part 7 b. The positive locking between the projection 30 and the support member 24 and the punch element 27 will, together with the clamping force exerted by the portion 15 of the second metal strip portion 7b on the portion 16 of the first metal strip portion 7a, achieve a clamping and locking effect on the first metal strip portion 7a and keep the first metal strip portion locked to the support member 24 during tightening of the elongated strip 3.

The distance D between said first and

second ends

25a, 25b of the recess 25 is at least 10mm, preferably at least 15 mm. The depth d of the recess 25 is at least 5mm, preferably at least 6 mm.

In the examples shown in fig. 2 a-2 i, 3 and 4, the recess 25 and the punch element 27 have a cross-sectional shape, as seen in a vertical plane, which is in the shape of an isosceles trapezoid. However, the recess 25 and the punch element 27 may also have any other suitable cross-sectional shape.

There is also an additional recess 42 in the upper support surface 26 of the support member 24, wherein the additional groove 42 is aligned with the channel 37 in the pressing member 35. The purpose of this further groove 42 is to ensure a gap between the first strip part 7a and the support member 24 below the welding area on the overlapping first and

second strip parts

7a, 7b, so as to prevent the material of said first strip part 7a from being subjected to heating and melting during the welding phase to adhere to the material of the support member 24 when said overlapping first and

second strip parts

7a, 7b are joined to each other by welding under the action of the laser beam 23 emitted from the laser welding head 22.

The electronic control means 60 may be configured to control the welding device 21 to direct a laser beam 23 (see fig. 2h) onto a region 14 (see fig. 7, 10 and 12) extending across the elongated strip 3 at the trailing end of the second metal strip portion 7b, i.e. at the end of the second metal strip portion 7b facing the feeding device 5, in order to reduce the tensile strength of the elongated strip 3 at the trailing end of the second metal strip portion 7b, wherein the electronic control means 60 is configured to control the feeding device 5 to retract the elongated strip 3 in order to subject the region 14 to a tensile stress, thereby breaking the elongated strip at the trailing end of the second metal strip portion 7 b. Thereby, the loop 11 arranged around the article or articles 10 to be bundled is released from the remaining part 3b of the elongated strap. As an alternative, the electronic control means 60 may be configured to control the welding means 21 to cut the elongated strip 3 at the trailing end of the second metal strip portion 7b by means of a laser beam 23, the laser beam 23 cutting the elongated strip over the entire thickness, thereby releasing the portion 3a of the elongated strip fed in one turn around the space 4 from the remaining portion 3b of the elongated strip.

The laser welding head 22 may include one or more computer controlled scanning mirrors for controlling the direction and movement of the laser beam 23 emitted from the laser welding head. As an alternative, the direction and movement of the laser beam 23 can be controlled by computer controlled movement of the entire laser welding head 22. The laser welding head 22 is provided with a focusing lens 38, and the laser beam 23 leaves the laser welding head via the focusing lens 38.

In the embodiment shown, the welding device 21 further comprises a laser source 39 (see fig. 2a) for generating the laser beam 23 for generating the required laser power, the laser beam 23 being used for forming the weld joint 8 between the first and

second strip portions

7a, 7b and for releasing the strip loop 11 from the remaining portion 3b of the elongated strip. The laser source 39 may be of any type commonly used for welding. In the example shown, the laser source 39 is connected to the laser welding head 22 via a fiber optic cable 40, the fiber optic cable 40 being configured to direct laser power generated by the laser source 39 to the laser welding head 22. The fiber optic cable 40 is connected to the laser welding head 22 in a conventional manner by an optical connector 41 that includes focusing optics. The focus of the laser beam 23 emitted from the laser welding head 22 can be adjusted by the laser brain controlled movement of one or more optical components included in the focusing optics of the optical connector 41.

The electronic control device 60 may be configured to control the welding device 21 to reduce the tensile strength of the elongated strip 3 at the tail end of the second metal strip portion 7b by heating the aforementioned region 14 at the tail end of the second metal strip portion 7b under the action of the laser beam 23 and without cutting or penetrating into the elongated strip 3. To heat the region 14 at the trailing end of the second metal strip portion 7b, the welding device 21 is caused to sweep the laser beam 23 across the region 14 (schematically illustrated in fig. 7 by dashed lines), which region 14 extends between the

longitudinal edges

17a, 17b of the elongated strip 3. In order to ensure that the laser beam 23 will heat the region 14 in question without cutting into the elongated strip 3, the focus of the laser beam 23 is adjusted, for example by the above-mentioned focusing optics of the optical connector 41, in such a way that: when hitting this region 14 at the trailing end of the second strip portion 7b, the laser beam is out of focus. When the zone 14 is rapidly heated by the laser beam 23, the feeding device 5 is operated to pull the elongated strip 3 backwards with such a force that: the elongated strip 3 is broken at the heating zone 14 under the effect of the tensile stress generated in the elongated strip between the feeding device 5 and the second metal strip portion 7 b.

As an alternative, the electronic control device 60 may be configured to control the welding device 21 to reduce the tensile strength of the elongated strip 3 at the trailing end of the second metal strip portion 7b by forming one or more recesses 18, 18' (see fig. 10-13) across the elongated strip 3 at the trailing end of the second metal strip portion 7b under the action of the laser beam 23, so as to thus provide a breaking line 19 across the elongated strip 3 at the trailing end of the second metal strip portion 7 b. In this case, the laser beam 23 is caused to cut into the elongate strip 3, but not to cut it. The recesses 18, 18' may, for example, have a depth corresponding to about half the thickness of the elongated strip 3. When the recesses 18, 18' are formed, the laser beam 23 is preferably prevented from reaching any

longitudinal edge

17a, 17b of the elongate strip 3. The break line 19 may be formed by several shorter recesses 18 arranged in line with each other across the elongated strip 3 at the trailing end of the second strip portion 7b (as shown in fig. 10 and 11) or by one longer recess 18' extending across the elongated strip 3 at the trailing end of the second strip portion 7b (as shown in fig. 12 and 13). When the breaking line 19 has been formed by the laser beam 23, the feeding device 5 is operated to pull the elongated strip 3 backwards with such a force that: the elongated strip 3 is broken at the breaking line 19 under the effect of the tensile stress generated in the elongated strip between the feeding device 5 and the second metal strip portion 7 b.

The electronic control means 60 may be implemented by a single electronic control unit or by two or more electronic control units cooperating with each other.

The sequence of operations for securing an elongate strap 3 by the machine 1 described above in such a way that the strap loops around a stack of articles 10 one turn will now be described with reference to figures 2 a-2 i.

In a first step, the motor of the infeed device 5 is operated in a first direction to feed the elongate strap 3 from the supply coil 6 forward through the strapping unit 20, one turn around the article receiving space 4 of the strapping machine 1 and back into the strapping unit 20. The front end 12 of the elongate strip is first moved over the support member 24 and the stamping element 27, then wrapped around the article receiving space 4 once, and then enters the space between the stamping element 27 and the recess 25 in the upper support surface 26 of the support member 24, wherein the feeding of the elongate strip 3 is stopped when the front end 12 of the elongate strip passes through the recess 25 from the first end 25a of the recess 25 to its opposite second end 25b and has reached a final position beyond the second end 25b of the recess.

During the feeding of the elongated strip 3, the pressing member 35 is in its retracted first position.

In the example shown, as shown in fig. 2a and 2b, the stamping element 27 is positioned within the recess 25 in the support member 24 and remains within the recess 25 until the leading end 12 of the elongate strip has passed the upper surface 28 of the stamping element 27 and the upper support surface 26 of the support member 24 before the leading end 12 of the elongate strip passes the initial supply of the strapping unit 20. In this case, therefore, the upper surface 28 of the stamping element 27 is flush, or at least substantially flush, with the upper support surface 26 of the support member 24 when the supply of the front end 12 of the elongate strip passes through the strapping unit 20 before encircling the article receiving space 4. The actuating means 29 then performs a relative movement between the punching element 27 and the support member 24 in order to position the punching element 27 at a distance from the recess 25 in the support member 24, wherein the punching element 27 lifts the elongated strip 3 from the upper support surface 26 of the support member 24, as shown in fig. 2 c.

When the elongated strip 3 is fed through the guide rail 2 in a manner encircling the article receiving space 4 one turn, the front end 12 of the elongated strip 3 will leave the guide rail 2 and pass through the gap between the punching element 27 and the support member 24 (see fig. 2d), whereupon the front end 12 of the elongated strip 3 actuates a stop member (not shown), thus stopping the motor of the feeding device 5. The actuating means 29 then performs a relative movement between the punch element 27 and the support member 24, so as to accommodate the punch element 27 in the recess 25 (see fig. 2e), so as to form a permanent protrusion 3 on the first strip portion 7a by means of a punch-forming action between the punch element 27 and the support member 24. Thereafter, as shown in fig. 2f, the motor of the feeding device 5 is reversed to pull the elongated belt 3 backwards, thereby tightening the elongated belt 3 around the articles 10 contained in the article receiving space 4. As shown in fig. 2e and 2f, the strapping unit 20 and the guide rail 2 are movable relative to the articles 10 and are configured to move towards the articles 10 when the elongated strap 3 is tightened around the articles. During retraction of the elongate strip 3, a portion 15 of the second strip portion 7b is pressed under tension of the elongate strip 3 against the upper support surface 26 of the support member 24 and against a portion 16 of the first strip portion 7a located between the second end 25b of the recess 25 in the support member and the front end 12 of the elongate strip, whereby the portion 16 of the first strip portion 7a is sandwiched between the support member 24 and the second strip portion 7b, as shown in fig. 4. During retraction of the elongate strip 3, the second strip portion 7b contacts the upper surface 28 of the punch element 27, thereby preventing the punch element 27 from moving vertically out of the recess 25 in the support member 24. Thereby, during tensioning of the elongated strip 3, the punch element 27 will remain in the recess 25 without the punch element 27 and the support member 24 being pressed against each other by the actuating means 29.

When the elongated strip 3 has been tightened around the objects 10, the motor of the feeding device 5 is stopped and the pressing member 35 is moved to its advanced second position, so as to press the first and

second strip portions

7a, 7b together between the pressing member 35 and the support member 24 (see fig. 2 g). The welding device 21 is then operated to focus the laser beam 23 onto the mutually overlapping

metal strip portions

7a, 7b in order to form a weld joint 8 between the

metal strip portions

7a, 7 b. Thereby securing the elongate strip 3 in a loop around the articles 10. Thereafter, as shown in fig. 2h, the welding device 21 is operated to direct a laser beam 23 onto a region 14 across the elongated strip 3 at the trailing end of the second strip portion 7b in order to reduce the tensile strength of the elongated strip 3 at the trailing end of the second strip portion 7 b. During the moment when the laser beam 23 is directed to the area 14, the portion of the elongated strip extending between the pressing member 35 and the feeding device 5 is advantageously kept in a relaxed state. Thereafter, the feeding device 5 is configured to retract the elongated strip 3 so as to subject the region 14 to a tensile stress, so as to break the elongated strip at the trailing end of the second metal strip portion 7 b. Finally, the pressing member 35 is returned to its retracted first position and the punch element 27 and the support member 24 are moved away from the projection 30 on the first strap part 7a to release the strap loop 11 from the strapping unit 20. Thus, as shown in fig. 2i and 5, the protrusions 30 will come into contact with the articles 10 and will therefore act as spacers between the articles 10 and the belt loop 11.

The intended welding area on the first and second

metal strip portions

7a, 7b is advantageously preheated by a laser beam emitted from a laser welding head 22 of the welding device 21 prior to the formation of the weld joint 8. The welding zone is preferably preheated to such a temperature that a possible layer of paint and/or wax on the first and second

metal strap parts

7a, 7b can be removed by evaporation at the intended welding zone. The preheating temperature is preferably also so adapted that the metallic material of the first and second

metal strap portions

7a, 7b is subjected to metallurgical changes, which may lead to improved welding conditions.

After the formation of the weld joint 8, the weld area on the first and second

metal strip portions

7a, 7b is advantageously post-heated also by a laser beam emitted from the laser welding head 22 of the welding device 21, wherein the post-heating temperature is so suitable that the metal material of the first and second

metal strip portions

7a, 7b is subjected to metallurgical changes, which can advantageously affect the strength of the weld joint 8.

In order to ensure that the laser beam heats the welding area for preheating and post-heating without cutting into the elongated strip 3, the focus of the laser beam is adjusted, for example by the above-mentioned focusing optics of the optical connector 41, in such a way that: when striking the second strip portion 7b during the pre-heating step and the post-heating step, the laser beam is out of focus. A pre-heated and post-heated laser beam is directed onto the outer surface of the second metal strip portion 7b, wherein thermal energy is transferred from the second metal strip portion 7b to the first metal strip portion 7a by thermal conduction.

The invention is of course not in any way restricted to the embodiments described above. On the contrary, many possibilities to modifications thereof will be apparent to a person with ordinary skill in the art without departing from the basic concept of the invention as defined in the appended claims. The strapping machine according to the invention can, for example, be designed to cooperate with a compacting machine for strapping a coil of wire which is compacted by the compacting machine. In the latter case, several strapping units are mounted to the compacting machine and used simultaneously in order to apply band loops at different positions around the compacted wire coil, wherein each band loop extends along the inside of the wire coil through its central axial opening and along the outside of the wire coil.

Claims

1. A strapping apparatus (1) for securing a length of metal strap (3a) in a loop (11) around one or more articles, the strapping apparatus (1) comprising:

a bundling unit (20) having:

-welding means (21) for forming a welded joint (8) between a first strip portion (7a) at the front end of a length of metal strip (3a) arranged in a loop around one or more objects (10) to be strapped and an overlapping second strip portion (7b) at the rear end of the length of metal strip (3a), so as to fix the length of metal strip (3a) in a loop around the one or more objects (10); and

a support member (24) for supporting the overlapping first and second strap portions (7a, 7b) during formation of the weld joint; and

-a feeding device (5) for feeding a metal belt (3) through the strapping unit (20), around an article receiving space (4) configured for receiving one or more articles (10) to be strapped, then back into the strapping unit (20) and subsequently retracting the metal belt (3) to tension the metal belt (3) around the one or more articles (10) received in the article receiving space (4);

the method is characterized in that:

providing a recess (25) in an upper support surface (26) on the support member (24);

-the strapping unit (20) comprises a punch element (27), the punch element (27) having a shape adapted to a recess (25) in the support member (24) such that the punch element (27) is receivable in the recess (25);

the strapping unit (20) comprising an actuating device (29), the actuating device (29) being configured to move the stamping element (27) and the support member (24) relative to each other between a first mutual position, in which the stamping element (27) is located at a distance from a recess (25) in the support member (24), and a second mutual position, in which the stamping element (27) is accommodated in the recess (25), wherein the stamping element (27) and the support member (24) are configured such that when the stamping element (27) and the support member (24) are moved relative to each other from the first mutual position to the second mutual position by means of the actuating device (29) and a portion of the first metal strap portion (7a) is accommodated in a space between the stamping element (27) and the support member (24), -forming a permanent protrusion (30) on the first metal strip portion (7a) at a position between the front end (12) of the length of metal strip (3a) and the weld joint (8) by means of a stamping forming action between the stamping element (27) and the support member (24); and

wherein the strapping machine comprises a pressing device (34) for pressing the second metal strap portion (7b) against the first metal strap portion (7a), wherein the pressing device (34) is configured to keep the second metal strap portion (7b) pressed against the first metal strap portion (7a) during the moment when the weld joint (8) between the first metal strap portion (7a) and the second metal strap portion (7b) is formed by the welding device (21).

2. Strapping machine (1) for fixing a length of metal strap (3a) in a loop (11) around one or more articles according to claim 1, wherein the punch element (27) has an upper surface (28), the upper surface (28) being flush or at least substantially flush with an upper support surface (26) on the support member (24) when the punch element (27) is received in the recess (25).

3. Strapping machine (1) for fixing a length of metal strap (3a) in a loop (11) around one or more articles according to claim 1 or 2, wherein the actuating device (29) is configured to effect the relative movement between the punching element (27) and the support member (24) by moving the punching element (27) relative to the support member (24).

4. Strapping machine (1) for fixing a length of metal strap (3a) in a loop (11) around one or more articles according to claim 1 or 2, wherein the actuating device (29) is configured to effect the relative movement between the punching element (27) and the support member (24) by moving the support member (24) relative to the punching element (27).

5. Strapping machine (1) for fixing a length of metal strap (3a) with a loop (11) around one or more articles according to claim 1, wherein the depth (d) of the recess (25) is at least 5 mm.

6. Strapping machine (1) for fixing a length of metal strap (3a) with a loop (11) around one or more articles according to claim 1, wherein the depth (d) of the recess (25) is at least 6 mm.

7. Strapping machine (1) for fixing a length of metal strap (3a) in a loop (11) around one or more articles according to claim 1 or 2, wherein the welding device (21) is a laser welding device.

8. Strapping machine (1) for securing a length of metal strap (3a) in a loop (11) around one or more articles in accordance with claim 7,

said pressing device (34) comprising a pressing member (35), said pressing member (35) being configured to cooperate with said supporting member (24), wherein said first metal strap portion (7a) and second metal strap portion (7b) are receivable in a space between said pressing member (35) and said supporting member (24), and wherein said pressing member (35) is movable with respect to said supporting member (24) between a retracted first position, in which said pressing member (35) is retracted from said supporting member (24), and an advanced second position, in which said pressing member (35) presses against said supporting member (24) to press said first metal strap portion (7a) and second metal strap portion (7b) together; and

the pressing member (35) is provided with a channel (37) through which a laser beam (23) from a laser welding head (22) of the welding device (21) can be directed to an area on the second metal strip portion (7b) when the pressing member (35) is in the second position and holds the first metal strip portion (7a) and the second metal strip portion (7b) pressed together between the pressing member (35) and the support member (24).

9. A method for securing a length of metal strap (3a) in a loop (11) around one or more objects, for use in a strapping machine (1) according to any of claims 1 to 8 for securing a length of metal strap (3a) in a loop (11) around one or more objects, the method comprising the steps of:

-feeding a metal strip (3) through a strapping unit (20) of a strapping apparatus (1) and round an article receiving space (4) of the strapping apparatus, wherein a leading end (12) of the metal strip is fed first on a support member (24) and a punch element (27) of the strapping unit (20), then round the article receiving space (4), and then into a space between the punch element (27) and a recess (25) in an upper support surface (26) of the support member (24), wherein the feeding of the metal strip is stopped when the leading end (12) of the metal strip has passed the recess (25) from a first end of the recess (25) to an opposite second end (25b) of the recess (25) and has reached a final position beyond the second end (25b) of the recess;

-pressing a portion of a first metal strip portion (7a) at the front end of the metal strip (3) into a recess (25) in the support member (24) by effecting a relative movement between the stamping element (27) and the support member (24), whereby the stamping element (27) is accommodated in the recess (25), and a permanent protrusion (30) is formed on the first metal strip portion (7a) by a stamping forming action between the stamping element (27) and the support member (24);

retracting the metal belt (3) to tighten the metal belt (3) around one or more articles (10) located in the article receiving space (4), wherein a portion (15) of a second metal belt portion (7b) at the trailing end of the length of metal belt (3a) fed in a loop around the article receiving space (4) is a portion (16) of a first metal belt portion (7a) pressed against an upper support surface (26) of the support member (24) under the tensile force of the metal belt (3) and abutting between a second end (25b) of a recess (25) in the support member and the leading end (12) of the metal belt, thereby sandwiching the portion (16) of the first metal belt portion (7a) between the support member (24) and the second metal belt portion (7 b); and

-forming a welded joint (8) between said first strap portion (7a) and said second strap portion (7b) by means of welding means (21) included in said strapping unit (20), so as to secure said length of metal strap (3a) in a loop (11) around said one or more objects.

10. Method for fixing a length of metal strip (3a) in a loop (11) around one or more articles according to claim 9, wherein the relative movement between the stamping element (27) and the support member (24) is achieved by moving the stamping element (27) towards the support member (24).

11. Method for fixing a length of metal strip (3a) in a loop (11) around one or more articles according to claim 9, wherein the relative movement between the stamping element (27) and the support member (24) is achieved by moving the support member (24) towards the stamping element (27).

12. Method for fixing a length of metal strip (3a) in a loop (11) around one or more objects according to any of claims 9-11, wherein,

-the stamping element (27) is positioned in a recess (25) in the support member (24) and retained in the recess (25) before the initial feeding of the leading end (12) of the metal strip through the strapping unit (20) until the leading end (12) of the metal strip has passed over the stamping element (27) and an upper support surface (26) of the support member (24); and

then, a relative movement between the punching element (27) and the support member (24) is effected in order to position the punching element (27) at a distance from the recess (25) in the support member (24), whereby the metal strip (3) is lifted from the upper support surface (26) of the support member (24) and the front end (12) of the metal strip is allowed to enter the space between the punching element (27) and the upper support surface (26) of the support member (24) when the front end of the metal strip is returned to the strapping unit (20) after encircling the article receiving space (4).

13. Method for fixing a length of metal strip (3a) in a loop (11) around one or more articles according to claim 12, wherein the above-mentioned relative movement between the punching element (27) and the support member (24) is achieved by moving the punching element (27) away from the support member (24).

14. Method for fixing a length of metal strip (3a) in a loop (11) around one or more articles according to claim 12, wherein the above-mentioned relative movement between the stamping element (27) and the support member (24) is achieved by moving the support member (24) away from the stamping element (27).

15. Method for fixing a length of metal strip (3a) in a loop (11) around one or more items according to claim 9, wherein the distance (D) between the first end (25a) of the recess (25) and the second end (25b) of the recess (25) is at least 10 mm.

16. Method for fixing a length of metal strip (3a) in a loop (11) around one or more items according to claim 9, wherein the distance (D) between the first end (25a) of the recess (25) and the second end (25b) of the recess (25) is at least 15 mm.