BACKGROUND OF THE INVENTION

.1. Field of the Invention

The present invention relates to a feeding and reversing mechanism tor a strapping machine and, more particularly, to a mechanism that can be used for retracting and tightening a strapping band for strapping machines.

2. Description of the Related Art

FIG 10 shows a conventional mechanism 90 for feeding and reversing a strapping hand for a strapping machine which includes a feeding motor 9.1 and a reversing motor 93. The feeding motor 91 drives a feeding wheel 911 to feed- a. strapping band 92 from a storage box for strapping objects or articles. The reversing motor 93 drives a reversing wheel 931 to retract the strapping band 92 for tightening the objects. Furthermore, first and second sensors 94 and 95 are provided for counting the rotating times of the feeding wheel 91 1 and the reversing wheel 931 respecti vely to help measure the length of the strapping band 92 being used, in order to provide and replenish the strapping band 92 accurately. However, the mechanism 90 needs two motors, i.e. the feeding motor 9.1 arid, the reversing motor 93, consuming more electricity. In. addition, there is only a point contact between the strapping band 92 and each of the feeding wheel 911 and the reversing wheel 931, which provide inadequate force for clamping the strapping band 92, resulting in slipping easily during the reversing process of the strapping band 92. Thus, the conventional feeding and reversing mechanism 90 is ineffective for strapping the objects.

BRIEF SUMMARY OF THE INVENTION

Thus, it is an objecti ve of the present invention to overcome the aforementioned shortcoming and deficiency of the prior art by providing a feeding and reversing mechanism for a strapping machine. The .feeding and reversing mechanism of the present invention can be used for retracting and tightening a. strapping band and has the advantages of simple structure. Further, the strapping band can be clamped tightly during the reversing process without slipping to provide a better strapping result,

To achieve the foregoing objective, a feeding and reversing mechanism for a strapping machine of the present invention includes a base, a forward-reverse wheel assembly, a tension wheel assembly, first and second arms, and first and second spring units:. The base includes an installation wall provided with a pivot thereon. The forward-reverse wheel assembly is mounted on the installation wall and includes an active wheel, and a passive wheel adjacent to the active wheel for Feeding and reversing a strapping band passing, between the active wheel and the passive wheel The tension wheel assembly is mounted on the installation wall and includes a. tension ^' active wheel and a. tension passive wheel adjacent to the tension active wheel. The first arm includes spaced first and second ends. The first end of the first arm is mounted around the pivot so that the first arm is pivotabie about an axis: defined by the pivot. The tension passive wheel is mounted on the second end of the first arm and movable relative to the tension active wheel. The second arm includes spaced first and second ends. The first end of the second arm is mounted around the pivot so that the second arm is pivotabie about the axis defined by the pivot, A rotary member is mounted to the second end of the second arm and is in contact with a cam. The first spring unit includes a spring and a fixing piece and is mounted on the first arm by extending the fixing piece through the spring and the first arm. The spring biases the first aim so that a gap is provided between the tension passive wheel and the tension active wheel for the strapping band to pass through. The second spring unit includes a tension spring and a fastener and is installed on the first and second arms by extending the fastener through the tension spring, the first arm. and the second arm. The second arm is pivoted to move the tension passive wheel and the first arm when the cam rotates, so thai the tension passive wheel is moved toward the tension active wheel, to clamp the strapping band securely.

In a preferred form, a band guiding member is disposed on the installation wall. The tension .active wheel is disposed below the band guiding member in a vertical direction, and the tension passive wheel is disposed above the tension active wheel in the vertical direction and adjacent to a bottom of the band guiding member. Further, the tension active wheel is disposed between the active wheel of the forward-reverse wheel assembly and the tension passive wheel.

Preferably; a contact surface between the strapping band and the tension active wheel is larger than half of an. outer periphery of the- tension active wheel, and a contact surface ^' between- the strapping band and the active wheel of the forward-reverse wheel assembly i s larger than, half of an outer periphery of the active ^' wheel.

The present invention will become clearer in light: of the following detailed description of an illustrative embodiment of this, invention described in connection with the drawings.

DESCRIPTION OF THE DRAWINGS

The illustrative embodiment: may best be described by reference to the accompanying drawings where:

FIG Ϊ shows a diagrammatic, perspecti ve view of a strapping machine utilizing a feeding and reversing .mechanism according to the preferred teachings of the present invention;

FIG 2 shows a perspective view of the feeding and reversing mechanism of the present invention, with the feeding and reversing mechanism being a part of a machine center of the strapping machine of FIG I;

FIG 3 is a front plan view of the feeding and reversing mechanism of FIG. 2; FIG 4 is an exploded, perspective view of the feeding and reversing mechanism of FIG 2;

FIG 5 is a partial, exploded, perspective view of the feeding and reversing mechanism of FIG, 4;

FIG 6 is. a view showing an assembled state of a first spring unit and a first arm of the feeding and reversing mechanism of FIG. 2;

FIG 7 is a view showing an assembled state of a second spring unit and a second arm of the feeding and .reversing mechanism of FIG. 2;

FIG % is a movement illustration of a cam and a rotary- member of the feeding and reversing mechanism of FIG 7;

FIG 9 shows a diagrammatic view of another type of strapping machine utilizi ng the feeding and reversing mechanism according to the preferred teachings of the present invention; and

FIG 10 is an illustration of a conventional feeding and reversing mechanism for a strapping machine.

DETAILED DESCRIPTION OF THE INVENTION FIG 1 shows a door-shaped strapping machine including a frame 10,. a machine center .11, a movable member 15, and two band rails 1.3: and 131. The machine center 1.1 is installed between an. upper bar 12 and a lower bar 121. The upper bar 12 can be moved by transmission of chain wheel and chain (not shown) so that, the machine center 1 1 is movable upward and downward with, the upper bar 12. The band rails 1.3 and 1.31 are disposed on two vertical sides of the frame 10. Two ends of the lower bar .12 ! are connected to the band rails 13 and. 131 respectively. The movable member 15 is in the form of a rai! and. is movably mounted in a chassis 16. During a strapping process, the movable member 15 is driven out from the chassis 16 and disposed under the band rails 13 and 131, so that the movable member 15, the lower bar 121, and the band rails 13 and .131 together form a rectangular band rail for transporting a strapping band 18. A. band storage mechanism 17 is installed on the chassis 1.6 for storing the strapping band 18.

A feeding and reversing mechanism for a strapping machine according to the preferred teachings of the present, invention is shown of FIGS. 2 through 8 of the drawings and generally designated 3. The feeding and reversing mechanism 3 of the present invention is a part of the machine center 1.1 in. FIG. t, allowing me strapping band 18 to be able to strap objects tightly. The feeding and reversing mechanism 3 includes a base 200, a forward-reverse wheel assembly 30, a tension wheel assembly 40, first and second amis -50 and 55, and first and second spring units 43 and 45. The base 2.00 includes a vertical installation wail 2.01 and a horizontal base plate 203 The installation wail 20.1 is disposed above the lower bar 121 and provided with a pivot 501. A gear drive assembly 2.1 is disposed on the installation wall 201 for driving the forward-reverse wheel assembly 30 and the tension wheel assembly 40. A band guiding member 22 with a guiding groove is mounted, on the installation wall 201 for directing the strapping band 18 to feed or retract. An operation area 24 is disposed below the base plate 203 for fusing and cutting the- strapping band I S (see FIG. 2).

The forward-reverse wheel assembly 30 includes aft active wheel 32 and a passive wheel 33 (FIG. 4). The active wheel 32 is mounted on the installation wall 201 and driven by a motor 31. The passive wheel 33 is connected to one end of a swing arm 331 so that, the passive wheel 33 is movable relative to the active wheel 32. The other end of the swing arm 33.1 is mounted on the installation wall 20.1 and engaged with a pressing bar 34. When the pressing bar 34 is pulled, the swing arm 331. and the passive wheel 33 are moved together away from the active wheel 32, allowing the strapping band IS to be extended through between the active wheel 32 and. the passive wheel 33. Furthermore, a. spring 332 is connected between the swing arm 331 and the installation wall 201. The elasticity of the spring 332 biases the passive wheel 33 towards -the active wheel. 32 when the pressing bar 34 is released, so that the passive wheel 33 and the active wheel 32 can clamp the strapping band 18 for feeding and reversing the strapping band 18.

The tension wheel assembly 40 includes a tension active wheel 41 and a tension passive wheel 42, The tension active wheel 41 is mounted on the installation wall 201 and can be driven by the gear drive assembly 21 to turn. The tension active wheel 41 is disposed below the band guiding member 22 in a vertical direction. The tension passive wheel 42 is disposed above the tension active wheel 41 in the vertical direction and adjacent to a. bottom of the. band guiding member 22. .Moreover, the tension active wheel 41 is disposed between the active wheel 32 of the forward-reverse wheel, assembly 30 and the tension passive wheel 42, When the strapping band 18 extends downward from the band, guiding member 22, it will go around the tension active wheel 41 and then the active wheel 32, such thai a contact surface between the strapping band I S and the tension active wheel 41 is larger than half of an outer periphery of the tension active wheel 41, and such that a contact surface between the strapping band 18 and the active wheel.32 is larger than half of an outer periphery of the active wheel 32 (FIG 3).

The first arm 50 includes spaced first and second ends 51 and 54, The first end 51 is installed around the pivot 501 of the installation wall 201 (FIG 5), so that the first ami 50 is pivoiable about an axis defined by the pivot 501. The tension passive wheel 42 is mounted to the second end 54 of the first arm 50, allowing joint movement of the tension passive wheel 42 and the first arm 50 relative to the tension active wheel 41. The first arm 50 includes a first engaging ear 52 formed on a bottom thereof and adjacent to the first end 51, The first arm 50 further includes a second engaging ear 53 formed on a top thereof and adjacent to the second end 54, Furthermore, a sensing piece 421 is disposed on an end. surface of the second end 54 of the first, arm 50 for sensing if the rotating speeds of the tension active wheel 41. and tension passive wheel 42 are the same (ft is not a feature of the present Invention and therefore will not be mentioned, in details).

The second arm 55 includes spaced first and second ends 551 and. 553, The first end 551 is mounted on the pivot 501 of the installation wail 201 (FIG 5), so that the second arm 55 is pivotable about the axis defined by the pivot 501. The second end 553 is an L-shaped bend relative to the first end 551. and extends in parallel: to the axis of the pivot 501. A rotary member 56 which is a bearing in this embodiment is mounted on. the second end 553 and gets in contact with a cam 57 driven hy a motor 571, so that the second arm 55 swings when the cam 57 rotates. The second arm 55 includes a connecting: ear 552 which, is aligned with the second, engaging ear 53 of the first arm 50 in the vertical direction.

The- first, spring unit 43 includes a spring 432 and a fixing piece 431. The fixing piece 431 extends through the spring 432. an installation plate 433 protruded from the installation -Wall 201, and the first engaging ear 52 of the first ami 50. A nut 434 is coupled to an end of the fixing piece 431 to install the first spring unit 43 on the first arm 50, The spring 432: can bias the ^■■ first arm 50 so that a gap is maintained between the tension passive wheel 42 and the tension active wheel 41 for the strapping band 18 to pass through .

The second spring unit 45 includes a tension spring 452 and a fastener 451, The fastener 45.1 extends through the tension, spring 452,. a washer 453,, the second engaging ear 53 of the first arm 50, and the connecting ear 55.2 of the second arm 55, and a nut 454 is coupled to an end of the fastener 45.1 to install the second spring unit 45 on. the first and second arms 50 and 55,

The procedures for strapping objects using the strapping machine are mentioned hereinafter. When an object 26 is placed on a conveyor 25 (see FIG. 1) and touches a photoelectric switch on the conveyor 25, the machine center 11 will descend and stop at a preset position near the object 26. As the machine center 1 1 descends, the movable member 15 extends out from the chassis 16 and reaches under the two band rails 13 and 131.. Then, the band storage mechanism 1.7 starts feeding the strapping band 18. During the feeding process, the strapping band 18 delivered from the band storage mechanism 17 extends downward from the band guiding member 22 (see FIGS. 1 through 3), goes, around the tension, active wheel 41 and the active wheel 32, then passes through, the lower bar 121 , the band rail 131, the movable member 15, the band rail. 13, and finally reaches the operation area 24. When the strapping band 18 reaches a preset location, a pliotoelectne switch in the machine center 11 will sense that and activate the motor 31 to turn the. .forward-reverse ^' wheel assembly 30 reverse!)' to retract the strapping band 18. When the. strapping band 18 is retracted to a preset distance- from the object 26, photoelectric switches on the band rails 13 and 131. will detect that and activate the motor 571. to turn the cam 57 .so that, the strapping band .18 is tightened to strap the object 26 tightly. The strapping band 18 is then being fused, and cut to finish strapping the object 26.

The feeding and reversing mechanism. 3 of the present invention can provide better strapping and tightening results for the object 26. More specifically, the contact surfaces between the strapping band 1.8 and the tension active wheel 4.Ϊ as ^' we ^' ll as the active wheel 32 are larger than half of the outer peripheries of the tension acti ve wheel 41 and. the active wheel 32. Therefore, the strapping band 18 can be clamped tightly without slipping during the reversing process. Moreover, when the strapping band .18 is being reversed, the motor 571. drives the cam 57 to rotate intennittently. When the protrusion, portion of the cam 57 presses against the rotary member 56, the second arm 55 swings downward with, the pivot 501 as the fulcrum (FIG: 7); therefore, the second spring unit 45 and the first arm 50 are moved to press the tension passive wheel 42 against the tension active wheel 41 to further clamp the strapping band 18 tightly, enhancing the result, of strapping the obj ect 26. Furthermore, when the strapping process is finished, Ae elasticity of the spring 431 of the first spring unit 43 returns the first arm 50 and the tension passive wheel 42 back to their original positions, in order to facilitate the feeding process of the strapping band 18 tor a next strapping operation,

FIG. 9 shows a. feeding and reversing mechanism 3 of the present invention being applied in another type of strapping machine 70. The strapping machine 70 has an arch frame 71 on a top thereof and the object 26 is placed in the arch frame 71, The machine center 13 including: the feeding and reversing mechanism 3 of the present invention is provided in the strapping -machine 70. However, when the- feeding and reversing mechanism 3 of the present invention is applied in this type of strapping machine 70, the assembling direction, of the feeding and reversing mechanism 3 is opposite to that, of the strapping machine shown in FIG. 1, wherein the pressing bar 34 poi nts do wnwa rd .

Thus since the invention disclosed herein may be- embodied in other specific forms without departing from the spirit or general characteristics thereof some of which forms have been indicated, the embodiments described herein are to be considered m all respects illustrative- and not restrictive. The ^' scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.