Strapping apparatus

1. A strapping apparatus for strapping an article with a strapping band, the strapping apparatus comprising:

a tensioning device comprising a rotatable tensioning wheel;

a tensioning counter-holder surface adjacent the tensioning wheel;

a sealing device comprising a sealing counter-holder surface and a sealing element movable toward the sealing counter-holder surface, wherein the sealing counter-holder surface is angularly offset relative to the tensioning counter-holder surface in a direction transverse to a longitudinal direction of the strapping band when positioned in the tensioning and sealing devices; and

a controller configured to:

after the strapping band has been clamped between the tensioning wheel and the tensioning counter-holder surface, cause the tensioning wheel to rotate to draw tension in the strapping band; and

cause the sealing element to move toward the sealing counter-holder surface to clamp two overlying layers of the strapping band between the sealing element and the sealing counter-holder surface, thereby causing a portion of the strapping band to twist across an entire width of the portion of the strapping band, and cause the sealing element to activate to seal the two overlying layers to each other.

2. The strapping apparatus of claim 1 , wherein the sealing device comprises a friction-welding device, wherein the sealing element comprises a welding shoe, and wherein the controller is configured to cause the sealing element to activate by causing the welding shoe to oscillate.

3. The strapping apparatus of claim 1 , further comprising a base plate having a planar base surface, wherein the sealing counter-holder surface is angularly offset relative to the base surface in the direction transverse to the longitudinal direction of the strapping band when positioned in the tensioning and sealing devices.

4. The strapping apparatus of claim 1 , wherein the sealing counter-holder surface is angularly offset relative to the tensioning counter-holder surface by 45 degrees or less.

5. The strapping apparatus of claim 4 , wherein the sealing counter-holder surface is angularly offset relative to the tensioning counter-holder surface by about 3 degrees.

6. The strapping apparatus of claim 1 , further comprising a rocker that comprises the tensioning counter-holder surface, wherein the rocker is movable to move the tensioning counter-holder surface toward and away from the tensioning wheel.

7. The strapping apparatus of claim 6 , wherein the rocker is pivotable about a rocker pivot axis to move the tensioning counter-holder surface toward and away from the tensioning wheel, the strapping apparatus further comprising a rocker lever operable to control movement of the rocker.

8. The strapping apparatus of claim 1 , further comprising a motor operably connected to the tensioning wheel to rotate the tensioning wheel and to the sealing element to activate the sealing element.

9. The strapping apparatus of claim 8 , wherein the controller is configured to cause the tensioning wheel to rotate by controlling the motor to rotate the tensioning wheel and to cause the sealing element to activate by controlling the motor to activate the sealing element.

10. The strapping apparatus of claim 1 , wherein the sealing counter-holder surface is angularly offset relative to the tensioning counter-holder surface such that, once the sealing element moves away from the sealing counter-holder surface after the sealing element seals the two overlying layers of the strapping band to each other, resetting forces present in the strapping band cause the strapping band to untwist and detach from the sealing counter-holder surface.

11. The strapping apparatus of claim 1 , wherein the tensioning counter-holder surface is concave in the longitudinal direction of the strapping band when positioned in the tensioning and sealing devices.