All electric friction fusion strapping tool

A tool for tensioning a loop of thermoplastic strap and sealing overlapping strap segments about an article, said tool comprising:

• a first rotatably mounted shaft;
• reversible motor means for rotating said first shaft initially in a first direction and then in a second, opposite direction;
• a second, rotatably mounted shaft;
• tension means drivably engaged with said second shaft for tensioning said loop;
• first clutch means drivably connecting said first shaft with said second shaft for rotating said second shaft in said first direction to tension said loop and adapted to disengage said second shaft from said first shaft when said first shaft is rotated in said second direction;
• sensing and control means for sensing a predetermined level of tension in said strap loop and for reversing the rotation of said motor means to change the rotation of said first shaft from said first direction of rotation to said second direction of rotation;
• and
• means responsive to rotation of said first shaft in said second direction for pressing said strap segments together after said strap loop has been tensioned to said predetermined level and for moving at least one of said overlapping strap segments relative to the other strap segment to effect a friction fusion weld of said overlapping segments.

A tool for tensioning a loop of thermoplastic strap and sealing overlapping strap segments, about an article, said tool comprising:

• a first rotatably mounted shaft;
• reversible motor means for rotating said first shaft initially in a first direction and then in a second, opposite direction;
• a second rotatably mounted shaft;
• transmission means drivably engaged with said second shaft;
• tension wheel means engaged with said transmission means for tensioning said loop;
• first clutch means drivably connecting said first shaft with said second shaft for rotating said second shaft in said first direction to tension said loop and adapted to disengage said second shaft from said first shaft when said first shaft is rotated in said second direction;
• sensing and control means for sensing a predetermined level of tension in said strap loop and for reversing the rotation of said motor means to change the rotation of said first shaft from said first direction of rotation to said second direction of rotation;
• means responsive to rotation of said first shaft in said second direction for pressing said overlapping strap segments together after said strap loop has been tensioned to said predetermined level;
• and
• oscillating drive means on said first shaft for oscillating said strap pressing means to move one of said overlapping strap segments relative to the other overlapping strap segment to effect a friction fusion weld of said overlapping segments.

A tool for tensioning and sealing a loop of thermoplastic strap that encircles an article and has first and second overlapping strap segments, said tool comprising:

• a frame;
• a first shaft mounted for rotation about its longitudinal axis relative to said frame;
• a reversible motor carried by said frame for rotating said first shaft sequentially in first and second directions;
• a second shaft mounted for rotation about its longitudinal axis relative to said frame;
• tension means mounted to said frame for tensioning said loop;
• means drivably connecting said second shaft with said tension means;
• first clutch means drivably connecting said first shaft with said second shaft for rotating said second shaft in said first direction to tension said loop and adapted to disengage said second shaft from said first shaft when said first shaft is rotated in said second direction;
• means for sensing a predetermined level of tension in said strap loop;
• control means responsive to said loop tension sensing means for reversing the rotation of said motor from said first direction of rotation to said second direction of rotation when said predetermined loop tension level is sensed by said tension sensing means;
• means responsive to rotation of said first shaft in said second direction for pressing said first and second overlapping strap segments together after said strap loop has been tensioned to said predetermined level;
• and
• oscillating drive means on said first shaft for oscillating said strap pressing means to move said first overlapping strap segment generally transversely of the strap length relative to the second overlapping strap segment to effect a friction fusion weld of said overlapping segments.

An all-electrically operated tool for tensioning and sealing a loop of thermoplastic strap that encircles an article and has first and second overlapping strap segments, said tool comprising:

• a frame;
• a first shaft mounted for rotation about its longitudinal axis relative to said frame, said first shaft defining a receiving bore having a longitudinal axis concentric with the longitudinal axis of rotation of said first shaft;
• an electrically operated, reversible motor carried by said frame for rotating said first shaft sequentially in a first direction and then in a second, opposite direction;
• a second shaft having one end received in said first shaft receiving bore and mounted for rotation about its longitudinal axis relative to said frame;
• a tension means mounted to said frame for initially gripping said first overlapping segment of the strap and moving said strap to tension said loop;
• transmission means drivably connecting said second shaft with said tension means;
• at least one one-way clutch means within said first shaft receiving bore for engaging said first and second shafts to permit rotation of said second shaft with said first shaft in said first direction to tension said strap loop and to permit said first shaft to rotate in a second, opposite direction without effecting a rotation of said second shaft in said second direction;
• means for sensing a predetermined level of tension in said strap loop;
• control means responsive to said loop tension sensing means for reversing the rotation of said motor from said first direction of rotation to said second direction of rotation when said predetermined loop tension level is sensed by said tension sensing means;
• means responsive to the rotation of said first shaft in said second direction for pressing said first and second overlapping strap segments together after said strap loop has been tensioned to said predetermined level;
• and
• oscillating drive means on said first shaft for oscillating said strap pressing means to move said first overlapping strap segment generally transversely of the strap length relative to the second overlapping strap segment to effect a friction fusion weld of said overlapping segments.

A tool for constricting and closing a loop of thermoplastic strap that encircles an article and has overlapping strap segments, said tool comprising:

• means for constricting said loop;
• reversible motor means for rotating initially in a first direction and then in a second, opposite direction;
• drive shaft means driven by said reversible motor means sequentially in said first and second directions of rotation for engaging and operating said constricting means to constrict said strap loop only when said drive shaft means is rotated in said first direction;
• sensing and control means for sensing a predetermined level of tension in the constricted strap loop and for reversing the rotation of said motor means to change rotation of said drive shaft means from said first direction of rotation to said second direction of rotation;
• means responsive to rotation of said drive shaft means in said second direction for pressing said overlapping strap segments together after said strap loop has been constricted to said predetermined tension level;
• and
• oscillating drive means on said drive shaft means for oscillating said strap pressing means to move at least one of said overlapping strap segments generally transversely of the strap length relative to the other strap segment to effect a driction fusion weld of said overlapping segment.

In a tool for constricting and closing a loop of thermoplastic strap that encircles an article and has overlapping strap segments and that has a frame on which is mounted means for constricting said loop;

• sensing and control means for sensing a predetermined level of tension in the constricted strap loop;
• and means responsive to said sensing and control means for pressing the overlapping strap segments together after the loop has been constricted to said predetermined tension level and for moving at least one of said overlapping strap segments generally transversely of the strap length relative to the other strap segment to effect a friction fusion weld of said overlapping segments;
• the improvement comprising:
• a saw blade having projecting saw teeth, said saw blade being pivotably mounted on said frame and being restrained against reciprocating movement, said saw blade being adapted to be pivoted between a lowered position for contacting a surface of said one overlapping strap segment and an elevated position in which the strap may be disposed in, or removed from the tool whereby, when said pressing means is moving said one overlapping strap segment relative to said other overlapping strap segment to effect a friction fusion weld of the overlapping segments, said one overlapping strap segment is moved across the teeth of said saw blade so that said saw blade cuts through said one overlapping strap segment before the welding of the straps is completed and thereby at least substantially severs the trailing portion of the strap loop from the tensioned strap loop encircling the article.

In a tool for constricting and closing a loop of thermoplastic strap that encircles an article and has overlapping strap segments, said tool comprising:

• a frame;
• means for constricting said loop;
• sensing and control means for sensing a predetermined level of tension in the constricted strap loop;
• means responsive to said sensing and control means for pressing the overlapping strap segments together after the loop has been constricted to said predetermined tension level and for moving at least one of said overlapping strap segment generally transversely of the strap length relative to the other strap segment to effect a friction fusion weld of said overlapping segments;
• a saw blade pivotally mounted on said frame and having downwardly projecting saw teeth, said saw blade being restrained against reciprocating movement and being adapted to be pivoted between a lowered position contacting an upper surface of said one overlapping strap segment and an elevated position spaced from the upper surface of said one overlapping strap segment, said saw blade including means for being engaged by said pressing means and being moved to said elevated position from said lowered position;
• and
• means for biasing said saw blade against the upper surface of said one overlapping strap segment when said pressing means is moving said one overlapping strap segment relative to said other overlapping strap segment to effect a friction fusion weld of the overlapping segments thereby causing said saw blade to cut through said one overlapping strap segment before the welding of the straps is completed and to thus at least substantially sever the trailing portion of the strap loop from the tensioned strap loop encircling the article.