Strapping apparatus

Abstract

A strapping apparatus has a frame, a single drive motor carried on the frame and having an output shaft, a feed roller connected to the motor and rotatable on the frame, and a tightening roller connected to the motor and rotatable on the frame. A strap from a supply is spanned over and passes between the feed and tightening roller to the object. A lever is pivoted on the frame parallel to the feed and tightening axes for movement between two angularly offset end positions. A feed counter roller freely rotatable on the lever is engageable in one of the end positions with the feed roller to pinch and advance the strap toward the object, and a tightening counter roller rotatable on the lever is engageable in the other of the end positions with the tightening roller to pinch and pull the strap away from the object.

Claims

1. An apparatus for strapping an object, the apparatus comprising: a frame plate having a front side and a back side; a single drive motor carried on the back side of the frame plate and having an output shaft; a driven feed roller connected to the motor and rotatable on the frame plate about a feed axis; a tightening roller connected to the motor and rotatable on the frame plate about a tightening axis parallel to the feed axis, a strap from a supply being spanned over and passing between the feed and tightening roller to the object; a lever pivoted on the front side of the frame plate about an axis parallel to the feed and tightening axes for movement between two angularly offset end positions; a feed counter roller freely rotatable on the lever and engageable in one of the end positions of the lever with the driven feed roller to pinch and advance the strap toward the object; a tightening counter roller rotatable on the lever and engageable in the other of the end positions with the tightening roller to pinch and pull the strap away from the object, the tightening counter roller being spaced from the tightening roller when the lever is in the one end position and the feed counter roller being spaced from the driven feed roller when the lever is in the other end position; a joining device for connecting the ends of the strap that is wrapped around the object; a transmission on the back side of the plate and connected between the drive motor and the tightening roller; a bearing on the back side of the plate; a shaft in the bearing and connected between the driven feed roller and the drive motor; respective input wheels on the motor output shaft, the transmission, and the bearing, the input wheels being on the back side of the plate; and a flexible drive element interconnecting the input wheels.

2. The apparatus defined in claim 1, wherein the drive motor continuously rotates both the driven feed roller and the tightening roller.

3. The apparatus defined in claim 1, further comprising: a transmission between the drive motor and the tightening roller so that the driven feed roller rotates at a higher speed than the tightening roller.

4. The apparatus defined in claim 1, further comprising: a bearing on the plate holding a shaft connected between the driven feed roller and the drive motor.

5. The apparatus defined in claim 1, wherein the wheels are toothed pulleys and the drive element is a toothed belt.

6. The apparatus defined in claim 1, wherein the lever has a long leg and a short leg extending transversely from an end of the long leg.

7. An apparatus for strapping an object, the apparatus comprising: a frame; a single drive motor carried on the frame and having an output shaft; a feed roller connected to the motor and rotatable on the frame about a feed axis; a tightening roller connected to the motor and rotatable on the frame about a tightening axis parallel to the feed axis, a strap from a supply being spanned over and passing between the feed and tightening roller to the object; a lever having a long leg with an outer end pivoted on the frame about an axis parallel to the feed and tightening axes for movement of the lever between two angularly offset end positions and another end from which a short leg extends transversely; a feed counter roller freely rotatable on the lever and engageable in one of the end positions with the driven feed roller to pinch and advance the strap toward the object, the feed counter roller being carried on the long leg between the ends thereof; a tightening counter roller rotatable on the lever and engageable in the other of the end positions with the tightening roller to pinch and pull the strap away from the object, the tightening counter roller being spaced from the tightening roller when the lever is in the one end position and the feed counter roller being spaced from the driven feed roller when the lever is in the other end position, the counter roller being carried on an outer end of the short leg; and a joining device for connecting the ends of the strap that is wrapped around the object.

8. An apparatus for strapping an object, the apparatus comprising: a frame; a single drive motor carried on the frame and having an output shaft; a feed roller connected to the motor and rotatable on the frame about a feed axis; a tightening roller connected to the motor and rotatable on the frame about a tightening axis parallel to the feed axis, a strap from a supply being spanned over and passing between the feed and tightening roller to the object; a lever pivoted on the frame about an axis parallel to the feed and tightening axes for movement between two angularly offset end positions; a feed counter roller freely rotatable on the lever and engageable in one of the end positions with the driven feed roller to pinch and advance the strap toward the object; a tightening counter roller rotatable on the lever and engageable in the other of the end positions with the tightening roller to pinch and pull the strap away from the object, the tightening counter roller being spaced from the tightening roller when the lever is in the one end position and the feed counter roller being spaced from the driven feed roller when the lever is in the other end position; a joining device for connecting the ends of the strap that is wrapped around the object; and a spring urging the lever into the one end position.

9. The apparatus defined in claim 8, further comprising: another spring urging the lever into the other end position.

10. The apparatus defined in claim 9, further comprising: a cam actuator operable for preventing the other spring from moving the lever into the other end position but disengageable to allow the other spring to overcome the one spring and press the counter roller against the counter roller.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

(2) FIG. 1 is a schematic front view of the strapping apparatus according to the invention; and

(3) FIG. 2 is a schematic section through the object according to line II-II of FIG. 1.

SPECIFIC DESCRIPTION OF THE INVENTION

(4) The drawing illustrates a strapping apparatus that can wrap strap 1 around an object or goods to be strapped in a manner that is inherently known and explained in detail in the prior art referred to above. The strap 1 is fed in for this purpose from a strap supply coil 2 shown only in FIG. 1. The strapping apparatus, only portions of which are shown in FIG. 1, also comprises a joining device 3 that is only shown schematically here and in this embodiment and without limitation thereto is embodied as a friction welder. The joining device 3 ensures that ends of the strap 1 to be joined together after having been tightened around the object to be strapped are fixed to each other, in this case by friction welding. As will readily be understood, the joining device 3 can also effect the desired joining of the ends of the strap 1 in other ways. After joining, the strap is cut between the joint and the supply 2 by means not shown, normally a power shear.

(5) FIG. 2 further shows elements essential for the present invention, namely a drive motor 4 that in this embodiment and without limitation thereto rotates both a feed roller 5 and a tightening roller 6 about respective parallel axes 5′ and 6′. As can be seen in FIG. 2, the drive motor 4 is a (single) electric motor that, like a step-down transmission 7 and a shaft bearing 8 that are also visible here, are all mounted on the rear side of a mounting or frame plate 9. A lever 10, which will be considered in greater detail below, is mounted on the front side of the plate 9.

(6) As can be seen in section in FIG. 2, the drive motor 4, the transmission 7, and the shaft bearing 8 are each mounted on the plate 9 so their axes 4′, 6′, and 5′ are parallel to one another and perpendicular to the plate 9. Optimal weight distribution can thus be achieved. Moreover, mounting of the drive motor 4 “next to” the transmission 7 and the shaft bearing 8 ensures that the above-described elements 4, 7, 8 require relatively little installation space perpendicularly away from the plate 9. The motor 4 has an output shaft 25 carrying a belt pulley 11 for rotation about the axis 4′. A comparable belt pulley 12 is located on an input shaft 26 of the transmission 7. Likewise, an additional pulley 13 is mounted on the input end of a shaft 14 that is supported within the shaft bearing 8, defines the axis 5′, and carries the feed roller 5 at its output end on the other side of the frame plate 9. In addition, the transmission 7 is equipped with an integrated brake 15 that merely represents an option and ensures or can ensure that the transmission 7 and with it the tightening roller 6 mounted on its output shaft are stopped on completion of tightening of the strap 1.

(7) The individual belt pulleys 11, 12, 13 are driven synchronously by the drive motor 4 in this embodiment via a common transmission element 16, here a flexible toothed belt. Accordingly, in this embodiment and without limitation thereto the individual pulleys 11, 12, 13, which rotate about parallel axes 4′ 6′, and 5′, are also toothed. Overall, the drive motor 4 ensures that the transmission 7 also continuously rotates tightening roller 6 as well as the feed roller 5 via the interposed shaft bearing 8.

(8) In order to switch between a feeding out of the strap 1 already described above and a tightening of the strap, the above-mentioned pivotal two-arm lever 10 is provided according to the invention. The lever 10 is pivoted to the front side of the plate 9 on a pivot 17 defining a lever axis 10′ parallel to the axes 4,′, 5′, and 6′. This lever 10 carries at least two counter-rollers 5a and 6a freely rotatable about respective axes 5a′ and 6a′ parallel to the other axes 4′, 5, and 6′, the counter-roller 6a is juxtaposed with the tightening roller 6 and is thus embodied as a tightening counter-roller 6a. In contrast, the other counter-roller 5a is a feed counter-roller 5a juxtaposed with the feed roller 5, as will be explained in more detail below.

(9) It can be seen from the front view of FIG. 1 that the lever 10 is L-shaped with a long L-leg 10a and a short L-leg 10b. According to this embodiment, the feed counter-roller 5a is rotatably mounted in the center lengthwise of the long L-leg 10a. In contrast, the tightening counter-roller 6a is rotatably mounted on the outer end of the short L-leg 10b.

(10) The lever 10 can be pivoted slightly back and forth between end positions described below as indicated by a double arrow in FIG. 1 about its pivot axis 10′ defined by a pivot 17 that is here on the front side of the plate 9. The angular stroke of the L-shaped lever 10 between its end positions is generally less than 20° and usually even only 10° or less. The lever 10 is moved as a whole against the force of oppositely effective springs 18 and 19. In fact, in the context of this embodiment, a spring 18 that is associated with strap tightening and another spring 19 that primarily is effective when feeding out the strap 1 are provided.

(11) In order to pivot the L-shaped lever 10, an eccentric abutment mechanism 20, 21, 22 is provided. The eccentric mechanism 20, 21, 22 is composed specifically of a cam 20 carried on a shaft 24 and a cam roller 21 carried on a cam roller lever 22. The cam roller lever 22 is carried on a pivot 23 defining an axis 23′ also parallel to the axes 4, 5, 6, and 10′.

(12) Rotation of the cam 20 about its axis 24′ extending on the drawing plane or parallel thereto and perpendicular to all the other axes 4′, 5′, 6′, and 10′ has the effect that the cam roller lever 22 pivots on its pivot 23 via the cam roller 21, as is likewise indicated in FIG. 1. The L-shaped lever 10 is pivoted as a consequence of this, because the cam roller lever 22 bears at the end of the short L-leg 10b of the L-shaped lever 10 that is opposite the tightening counter-roller 6a on the cam 20, thereby “entraining” the lever 10 in its pivoting movement.

(13) For example, to feed out the strap 1, the L-shaped lever 10 is pivoted in the clockwise direction about its pivot 17 into its end feeding-out end position by rotation of the cam 20 to rotate the lever 22 clockwise and thereby rotate the lever 10 also clockwise and press the counter feed roller 5a against the feed roller 5. As a result, the feed counter-roller 5a comes to rest against the feed roller 5, and the strap 1 is pinched between the two rollers 5 and 5a. Consequently, the strap 1 is unwound at a relatively high speed from the strap supply 2 and can be wrapped around the object to be strapped by a strap guide for example. As soon as the strap 1 has been wrapped around the object, the loop of strap 1 around the object being strapped is cut from the strap supply 2 by the unillustrated cutter.

(14) The strap 1 is then tightened. To this end, the cam 20 allows the lever to pivot counterclockwise from the FIG. 1 position, such that the counter roller 5a pulls away from the roller 5, the counter roller 6a moves toward the roller 6, and the strap 1 is pinched between the tightening roller 6 and the tightening counter-roller 6a. The lever 10 is acted upon in the opposite counterclockwise direction by the eccentric 20, 21, 22 and moves into the opposite tightening end position under the force of the much stronger spring 18. As a result, the feed counter-roller 5a moves away from the feed roller 5, and the tightening counter-roller 6a pinches the strap against the tightening roller 6 instead, while compressing the weaker spring 19. The strap 1 that is pinched between the two rollers 6 and 6a can thus be tightened at slow speed with high torque applied to the rollers 6 and 6a. Moreover, the tightened ends of the strap 1 can be joined together by the joining device 3 as described above.