Strapping machine and method for securing a piece of metal strap in a loop around one or more objects

Abstract

A strapping machine comprising: —a feeding device for feeding astrap (3) around one or more objects and subsequently retracting the strap to draw it tightly around said objects; —a welding device for forming a welded joint between a first section at the leading end of the strap and an overlapping second section at the trailing end of a piece (3a) of the strap fed around said objects to thereby secure this piece in a loop around the objects; —a support member (24) for supporting said overlapping strap sections during the formation of the joint, a recess (25) being provided in an upper support surface (26) on the support member; and—a pressing element (27) with a shape adapted to the shape of said recess, the pressing element and support member being configured to form a permanent bulge (30) on the first strap section by a press forming action between the pressing element and the support member.

1 . A strapping machine for securing a piece ( 3   a ) of metal strap in a loop ( 11 ) around one or more objects, the strapping machine ( 1 ) comprising:
 a strapping unit ( 20 ) provided with:
 a welding device ( 21 ) for forming a welded joint ( 8 ) between a first strap section ( 7   a ) at a leading end of a piece ( 3   a ) of metal strap arranged in a loop around one or more objects ( 10 ) to be strapped and an overlapping second strap section ( 7   b ) at a trailing end of said strap piece ( 3   a ) to thereby secure this strap piece ( 3   a ) in a loop around said one or more objects ( 10 ), and 
 a support member ( 24 ) for supporting said overlapping first and second strap sections ( 7   a ,  7   b ) during the formation of the welded joint ( 8 ); and 
   a feeding device ( 5 ) for feeding the strap ( 3 ) through the strapping unit ( 20 ), in a loop around an object receiving space ( 4 ) configured for receiving one or more objects ( 10 ) to be strapped and then back into the strapping unit ( 20 ) and subsequently retracting the strap ( 3 ) to draw it tightly around one or more objects ( 10 ) received in the object receiving space ( 4 ); wherein   
       a recess ( 25 ) is provided in an upper support surface ( 26 ) on the support member ( 24 );
 the strapping unit ( 20 ) comprises a pressing element ( 27 ), which has a shape adapted to the shape of the recess ( 25 ) in the support member ( 24 ) to allow the pressing element ( 27 ) to be received in this recess ( 25 ); 
 the strapping unit ( 20 ) comprises an actuating device ( 29 ) which is configured to move the pressing element ( 27 ) and the support member ( 24 ) in relation to each other between a first mutual position, in which the pressing element ( 27 ) is positioned at a distance from the recess ( 25 ) in the support member ( 24 ), and a second mutual position, in which the pressing element ( 27 ) is received in said recess ( 25 ); and
 the pressing element ( 27 ) and the support member ( 24 ) are configured to form a permanent bulge ( 30 ) on the first strap section ( 7   a ) at a position between the leading end ( 12 ) of said strap piece ( 3   a ) and said welded joint ( 8 ) by a press forming action between the pressing element ( 27 ) and the support member ( 24 ) when the pressing element ( 27 ) and the support member ( 24 ) are moved in relation to each other by the actuating device ( 29 ) from said first mutual position to said second mutual position with a part of the first strap section ( 7   a ) received in the space between the pressing element ( 27 ) and the support member ( 24 ). 
 
 
     
     
         2 . A strapping machine according to  claim 1 , wherein the pressing element ( 27 ) has an upper surface ( 28 ) which is flush or at least essentially flush with the upper support surface ( 26 ) on the support member ( 24 ) when the pressing element ( 27 ) is received in said recess ( 25 ). 
     
     
         3 . A strapping machine according to  claim 1 , wherein the actuating device ( 29 ) is configured to achieve said relative movement between the pressing element ( 27 ) and the support member ( 24 ) by moving the pressing element ( 27 ) in relation to the support member ( 24 ). 
     
     
         4 . A strapping machine according to  claim 1 , wherein the actuating device ( 29 ) is configured to achieve said relative movement between the pressing element ( 27 ) and the support member ( 24 ) by moving the support member ( 24 ) in relation to the pressing element ( 27 ). 
     
     
         5 . A strapping machine according to  claim 1 , wherein the recess ( 25 ) has a depth (d) of at least 5 mm, preferably at least 6 mm. 
     
     
         6 . A strapping machine according to  claim 1 , wherein the strapping machine ( 1 ) comprises a squeezing device ( 34 ) for squeezing the second strap section ( 7   b ) against the first strap section ( 7   a ), and the squeezing device ( 34 ) is configured to keep the second strap section ( 7   b ) squeezed against the first strap section ( 7   a ) during the moment when the welded joint ( 8 ) between the first and second strap sections ( 7   a ,  7   b ) is formed by the welding device ( 21 ). 
     
     
         7 . A strapping machine according to  claim 1 , wherein the welding device ( 21 ) is a laser welding device. 
     
     
         8 . A strapping machine according to  claim 6 ,
 wherein
 the welding device ( 21 ) is a laser welding device; 
 the squeezing device ( 34 ) comprises a squeezing member ( 35 ) which is configured to co-operate with the support member ( 24 ); 
 the first and second strap sections ( 7   a ,  7   b ) are receivable in a space between the squeezing member ( 35 ) and the support member ( 24 ); 
 the squeezing member ( 35 ) is moveable in relation to the support member ( 24 ) between a retracted first position, in which the squeezing member ( 35 ) is retracted from the support member ( 24 ), and an advanced second position, in which the squeezing member ( 35 ) is pressed against the support member ( 24 ) to squeeze together the first and second strap sections ( 7   a ,  7   b ); and 
   the squeezing member ( 35 ) is provided with a passage ( 37 ), through which a laser beam ( 23 ) from a laser welding head ( 22 ) of the laser welding device ( 21 ) may be directed towards an area on the second strap section ( 7   b ) when the squeezing member ( 35 ) is in said second position and keeps the first and second strap sections ( 7   a ,  7   b ) squeezed together between the squeezing member ( 35 ) and the support member ( 24 ).   
     
     
         9 . A method for securing a piece ( 3   a ) of metal strap in a loop ( 11 ) around one or more objects, comprising the steps of:
 feeding the strap ( 3 ) through a strapping unit ( 20 ) of a strapping machine ( 1 ) and in a loop around an object receiving space ( 4 ) of the strapping machine, wherein the leading end ( 12 ) of the strap is first fed over a support member ( 24 ) and a pressing element ( 27 ) of the strapping unit ( 20 ), thereafter in a loop around said object receiving space ( 4 ) and then into a space between the pressing element ( 27 ) and a recess ( 25 ) in an upper support surface ( 26 ) on the support member ( 24 ), the feeding of the strap being stopped when the leading end ( 12 ) of the strap has passed over said recess ( 25 ) from a first end ( 25   a ) thereof to an opposite second end ( 25   b ) thereof and has reached a final position beyond said second end ( 25   b ) of the recess;   pressing a part of a first strap section ( 7   a ) at the leading end of the strap ( 3 ) into the recess ( 25 ) in the support member ( 24 ) by effecting a relative movement between the pressing element ( 27 ) and the support member ( 24 ) and thereby causing the pressing element ( 27 ) to be received in said recess ( 25 ) and a permanent bulge ( 30 ) to be formed on the first strap section ( 7   a ) by a press forming action between the pressing element ( 27 ) and the support member ( 24 );   retracting the strap ( 3 ) to draw it tightly around one or more objects ( 10 ) positioned in said object receiving space ( 4 ), wherein a part ( 15 ) of a second strap section ( 7   b ) at the trailing end of the piece ( 3   a ) of strap fed in a loop around the object receiving space ( 4 ) is pressed, under the effect of the tensional force in the strap ( 3 ), towards the upper support surface ( 26 ) on the support member ( 24 ) and tightly against a part ( 16 ) of the first strap section ( 7   a ) located between said second end ( 25   b ) of the recess ( 25 ) in the support member and the leading end ( 12 ) of the strap to thereby clamp this part ( 16 ) of the first strap section ( 7   a ) between the support member ( 24 ) and the second strap section ( 7   b ); and   forming, by a welding device ( 21 ) included in the strapping unit ( 20 ), a welded joint ( 8 ) between said first and second strap sections ( 7   a ,  7   b ) to thereby secure said strap piece ( 3   a ) in a loop ( 11 ) around said one or more objects.   
     
     
         10 . A method according to  claim 9 , wherein said relative movement between the pressing element ( 27 ) and the support member ( 24 ) is effected by moving the pressing element ( 27 ) towards the support member ( 24 ). 
     
     
         11 . A method according to  claim 9 , wherein said relative movement between the pressing element ( 27 ) and the support member ( 24 ) is effected by moving the support member ( 24 ) towards the pressing element ( 27 ). 
     
     
         12 . A method according to  claim 9 , wherein
 the pressing element ( 27 ) is positioned in the recess ( 25 ) in the support member ( 24 ) before the initial feeding of the leading end ( 12 ) of the strap through the strapping unit ( 20 ) and maintained in this recess ( 25 ) until the leading end ( 12 ) of the strap has passed over the pressing element ( 27 ) and the upper support surface ( 26 ) on the support member ( 24 ); and   a relative movement between the pressing element ( 27 ) and the support member ( 24 ) is thereafter effected to cause the pressing element ( 27 ) to be positioned at a distance from the recess ( 25 ) in the support member ( 24 ) to thereby lift the strap ( 3 ) from the upper support surface ( 26 ) on the support member ( 24 ) and allow the leading end ( 12 ) of the strap to pass into the space between the pressing element ( 27 ) and the upper support surface ( 26 ) on the support member ( 24 ) when the leading end of the strap returns to the strapping unit ( 20 ) after having passed around the object receiving space ( 4 ).   
     
     
         13 . A method according to  claim 12 , wherein the last-mentioned relative movement between the pressing element ( 27 ) and the support member ( 24 ) is effected by moving the pressing element ( 27 ) away from the support member ( 24 ). 
     
     
         14 . A method according to  claim 12 , wherein the last-mentioned relative movement between the pressing element ( 27 ) and the support member ( 24 ) is effected by moving the support member ( 24 ) away from the pressing element ( 27 ). 
     
     
         15 . A method according to  claim 1 , wherein the distance (D) between the first end ( 25   a ) of the recess ( 25 ) and the second end ( 25   b ) of the recess ( 25 ) is at least 10 mm, preferably at least 15 mm. 
     
     
         16 . A strapping machine according to  claim 2 , wherein the actuating device ( 29 ) is configured to achieve said relative movement between the pressing element ( 27 ) and the support member ( 24 ) by moving the pressing element ( 27 ) in relation to the support member ( 24 ). 
     
     
         17 . A strapping machine according to  claim 2 , wherein the actuating device ( 29 ) is configured to achieve said relative movement between the pressing element ( 27 ) and the support member ( 24 ) by moving the support member ( 24 ) in relation to the pressing element ( 27 ). 
     
     
         18 . A strapping machine according to  claim 17 , wherein the recess ( 25 ) has a depth (d) of at least 5 mm, preferably at least 6 mm. 
     
     
         19 . A strapping machine according to  claim 16 , wherein the recess ( 25 ) has a depth (d) of at least 5 mm, preferably at least 6 mm. 
     
     
         20 . A strapping machine according to  claim 20 , wherein the recess ( 25 ) has a depth (d) of at least 5 mm, preferably at least 6 mm.