EP0720948A1 - Strapping machine for packages, particularly stacks of magazines - Google Patents

Abstract

The tape wrapping machine has the tape dispensed into a vertical frame to wind around the items to be wrapped. The free end of the tape is secured by a first clamping ram (22) while the other end of the tap is subsequently secured by a second clamping ram (23) after tensioning the tape. The tape ends are then welded and the tape feed trimmed off. The second clamping ram is mounted coaxially inside the first for a compact layout. The welding process is assisted by an additional clamping ram which secures the overlapped tape for welding. The clamping rams are driven by a cam drive in a compact mounting.

Description

The invention relates to a device for strapping packaged goods with a strapping, in particular a transverse strapping machine for magazine stacks, with the features specified in the preamble of claim 1.

Strapping devices of this type conventionally have a machine table, an essentially vertical strap guide frame arranged thereon, in which the strapping strap can be passed around the stack as a loose loop, a shooting device for shooting the strap into the strap guide frame, a retraction device for pulling the strap around the stack of objects and a welding head with a clamping device for welding and fixing the strapping during retraction, welding and severing of the strapping from the supply of straps.

The known clamping devices of conventional welding heads have three plungers located one behind the other in the shooting-in direction of the strapping band, namely a first clamping plunger for fixing the free end of the inserted strapping band, a second clamping plunger for fixing the strapping band section overlapping with the free end in the tightened state and an auxiliary plunger assigned to the welding jaws Acting on the strapping sections to be welded together in a taut state.

The three plungers are each slidably mounted separately in the welding head and each is motion-controlled with its own drive in the form of an electrical, hydraulic, pneumatic or mechanical drive operating with the aid of a cam control. Due to the three plungers, this welding head has a relatively large overall length, so that in the case of a transverse strapping machine, very narrow stacks of objects, such as e.g. thin square strips, can no longer be strapped. In addition, it is disadvantageous that the control and sliding guidance of the three immediately adjacent plungers is structurally complex.

Proceeding from this, the object of the invention is to improve a strapping device of the generic type in such a way that its welding head has a more compact construction and is simpler in terms of construction for the actuation and sliding guidance of the plunger.

This object is achieved by the features specified in the characterizing part of claim 1. The welding head according to the invention is particularly compact due to the arrangement of the second clamping plunger within the first clamping plunger and its displaceable guidance therein. It practically saves the overall length for a plunger. Various advantages are achieved through this compactness. In this way, very narrow packaged goods can be strapped. The strapping machine can also be used universally for a wide variety of bandwidths.

In addition, the specified arrangement creates the prerequisite for the first and second clamping tappets to be able to be controlled in their clamping movements jointly by means of a single control drive, for example a common cam control by means of a control disk. This considerably reduces the design effort for the control. It also saves a significant number of moving parts for the machine. Last but not least, it has been shown that the machine according to the invention can be manufactured with relatively large manufacturing tolerances without losing its functionality.

Fig. 1

eine schematische Seitenansicht einer Umreifungsvorrichtung quer zur Umreifungsebene,

Fig. 2, 4, 6, 8, 10, 12 und 14

in der Umreifungsebene geschnittene Darstellungen des Schweißkopfes in unterschiedlichen Umreifungsstadien, sowie

Fig. 3, 5, 7, 9, 11, 13 und 15

entsprechende Schnittdarstellungen des Schweißkopfes quer zur Umreifungsebene entlang der Schnittlinien III-III, V-V, VII-VII, IX-IX, XI-XI, XIII-XIII bzw. XV-XV gemäß den Fig. 2, 4, 6, 8, 10, 12 bzw. 14.

Further features, details and advantages of the invention can be found in the subclaims and the following description, in which an embodiment of the subject matter of the invention is explained in more detail with reference to the accompanying drawings. Show it

Fig. 1

1 shows a schematic side view of a strapping device transverse to the strapping plane,

2, 4, 6, 8, 10, 12 and 14

in the strapping plane cut representations of the welding head in different strapping stages, as well

3, 5, 7, 9, 11, 13 and 15

corresponding sectional views of the welding head transverse to the strapping plane along the section lines III-III, VV, VII-VII, IX-IX, XI-XI, XIII-XIII or XV-XV according to FIGS. 2, 4, 6, 8, 10, 12 or 14.

As is clear from FIG. 1, the transverse strapping machine 1, which is used for the transverse strapping of a stack of magazines 2, has a machine frame 4 which is mounted on rollers 3 and which is provided with a machine table 5 at the top. A vertically directed strap guide frame 6 is arranged on this, which spans the strapping plane U. On the machine table 5, the magazine stack 2 can be moved in the insertion direction E into the clear opening 7 of the belt guide frame 6 and moved out of it again by conveyor belts (not shown).

In the machine frame 4, a supply roll 8 of the strapping band 9 is rotatably mounted, which is gradually withdrawn as needed via a deflection roller 10 and a dancer lever 11 from a pair of take-off rolls 12 into the belt supply store 13 in the machine frame 4.

From there, the strapping band 9 is inserted in the usual manner by means of a shooting device 14 into the welding head designated as a whole as 15 and on both sides thereof in the strapping plane U in the machine table 5 and tape guide frame 6 running tape guide channel 16 shot until the free end 17 comes to rest in the welding head 15 and overlaps with the strapping section 18 located below. The strap guide channel 16, as is indicated in its course by the strapping strap 9 shown in dash-dot lines, is formed in the usual manner in the machine table 5 and strap guide frame 6 and requires no further discussion.

For the usual operation of the cross strapping machine 1, it is only necessary to state that after the strapping 9 has been shot in by means of the insertion roller pair 19, the free end 17 of the strapping 9 is held in place and then the retraction roller pair 20 is set in motion in the opposite direction on the insertion and retraction device 14. The strapping band 9 is thereby pulled out of the band guide channel 16 until it tightly encloses the magazine stack 2. The excess tape supply is fed into the tape supply store 13.

When the strapping is pulled tight, the welding head 15 is then actuated in a manner to be discussed in more detail in order to fix the strapping loop loop stretched around the magazine stack 2 by welding and to separate it from the strapping band 9 entering the welding head 15. Then the finished strapped magazine stack 2 is transported out of the tape guide frame 6 in the insertion direction E.

The detailed structure of the welding head 5 is to be discussed with reference to FIGS. 2 and 3. For example, the welding head 15 has a clamping device 21 which has a first clamping plunger 22 for fixing the free end 17 of the strapping band 9 inserted, a second clamping plunger 23 for fixing the strapping band section 18 which overlaps with the free end 17 in the tightened state, and an auxiliary plunger 24 for loading the strapping strap sections 25, 26 to be welded together in the taut state. The first clamping plunger 22 and the auxiliary plunger 24 are arranged one behind the other in the strapping plane U. and in each case in schematically indicated guide parts 27, 28 on the machine frame 4 below the machine table 5 in the clamping direction K slidably. The second clamping plunger 23 is arranged within the first clamping plunger 22 and is displaceable therein in the clamping direction K relative to the latter. For this purpose, the first clamping plunger 22 is designed as a square profile which has a transverse wall 29 in the middle over its length. This is provided with a guide opening 30 in which the shaft 31 of the second clamping plunger 23 is slidably mounted. The head 32 of the second clamping plunger 23 lies within the cavity 34 facing the upper end 33 of the first clamping plunger 22. At the lower end, the shaft 31 of the second clamping plunger 23 continues into a fork-shaped joint head 35 which has two lateral, transverse to the strapping plane U. Cheeks 36, 37 has. At the lower end of the joint head 35, an axis 38 is inserted between the two cheeks 36, 37, on which a sleeve 39 is rotatably seated. The joint head 35 serves to connect the first and second clamping plungers 22, 23 to a common control drive 40 for controlling the movement of the two plungers, as will be explained in more detail below.

Between the top of the joint head 35 and the bottom of the transverse wall 29 of the first clamping plunger 22, a helical compression spring 41 is inserted, which acts on the two clamping plungers 22, 23 in the opposite direction. Furthermore, the first clamping plunger 22 has two lateral stops 42, 43 on its upper end face, which are formed by corresponding extensions of the side walls 44, 45 running parallel to the strapping plane U with respect to the side walls 46, 47 of the plunger 22 running at right angles thereto. Above these stops 42, 43 there is a clamping tongue 48 which engages from the side at right angles to the strapping plane U in the welding head 15 and which cooperates with a pressure plate 49 in the welding head 15 in the manner of pliers. Between the clamping tongue 48 and the pressure plate 49, a helical compression spring 50 is inserted into corresponding pockets 51, 52 in the clamping tongue 48 and the pressure plate 49, which presses the clamping tongue 48 and the pressure plate 49 apart.

The control drive 40 for the two clamping plungers 22, 23 has a control lever 53 designed as an operating lever, which is pivotably mounted in the welding head unit via a pivot axis 54 running parallel to the strapping plane U. The horizontal lever arm 55 engages with its rounded head end 56 between the cheeks 36, 37 of the joint head 35. The vertical lever arm 57 is provided approximately in the middle with a roller 58 which rolls on the outer circumference of a control disk 59. The control disk 59 is rotatably mounted on a shaft 60 which is driven by a control motor, not shown. At the lower end of the vertical lever arm 57, a helical tension spring 61 is suspended, which is mounted on the machine frame 4 and acts on the control lever 53 in a clockwise direction with respect to FIG. 3, so that, as a rule, the roller 58 bears non-positively on the outer circumference of the control disk 59. Their outer circumference is designed in the manner of a control curve 62 with three control sections 63, 64, 65 of different radii.

In the insertion direction S in front of the assembly of the first and second clamping plungers 22, 23 is the auxiliary plunger 24, which has at its lower end a joint head 35 'corresponding to the joint head 35 of the second clamping plunger 23 with cheeks 36', 37 ', axis 38' and sleeve 39 ' having. Also in accordance with the second clamping plunger 23, the movement of the auxiliary plunger 24 is controlled by a control drive 40 ', which has a control lever 53' with pivot axis 54 ', horizontal lever arm 55' and vertical lever arm 57 '. The control lever 53 'is kept in constant contact with the outer circumference of the control disk 59' via a roller 58 'via a helical tension spring 61', which is also seated on the shaft 60 'in a rotationally fixed manner. The outer circumference of the disk 59 'is in turn designed as a control cam 62' which has control sections 63 ', 64', 65 'and 66' of different radii distributed over its circumference.

On the front side in front of the auxiliary tappet 24 there is a guide plate 67 which can be displaced transversely to the strapping plane and whose edge pointing counter to the weft direction S is wedge-shaped. The pressure plate 49 also extends into the area above the guide plate 67.

On the side of the auxiliary plunger 24 pointing counter to the weft direction S, a cutting device 69 is provided for separating the welded strapping band 9 from the band supply, which has a movable knife jaw 70 arranged on the auxiliary plunger 24 and a counter knife jaw 71 arranged in a fixed position on the guide part 27. The latter has a wedge-shaped passage opening 72 narrowing in the weft direction S for the strapping band 9 entering the welding head 15, which forms a cutting edge 73 which interacts with the movable knife jaws 70. The movable knife jaw 70 is constantly acted upon in the direction of the counter knife jaw 71 by two small coil springs 78, which are accommodated in corresponding recesses 79 in the auxiliary tappet 24.

At the level of the guide plate 67, a welding tongue 74 which can also be displaced transversely to the strapping plane U is provided on the side thereof.

The mode of operation of the welding head 15 designed according to the invention is to be explained with reference to FIGS. 2 to 15:

In the starting position of the plungers 22, 23, 24 shown in FIGS. 2 and 3, these are maximally retracted downward due to the control cams 62, 62 ', so that between the pressure plate 49 and the clamping tongue 48 or the guide plate 67 on the one hand and between the clamping tongue 48 or guide plate 67 and the end faces of the second clamping plunger 23 and the auxiliary plunger 24, on the other hand, each have gaps 75, 76 for carrying out the strapping 9. The clamping tongue 48 rests on the two stops 42, 43 of the first clamping plunger 22.

By actuating the pair of insertion rollers 19, the strapping band 9 is inserted in the weft direction S through the lower gap 76 further into the band guide channel 16 in the band guide frame 6, where it is loosely guided around the magazine stack 2, which is indicated in a reduced manner in FIGS. 2, 4, ... until it runs into the upper gap 75. As soon as the free end 17 touches the touch contact 77 of a stop switch 77 ', the pair of insertion rollers 19 is put out of operation. Then will by the machine control, not shown, the shaft 60 is rotated clockwise, so that the roller 58 dips into the control section 64 of the control cam 62 and the control lever 53 is pivoted by a small angle (Fig. 4, 5). As a result, the first and second clamping plungers 22, 23 are pushed up a small distance, these two plungers not changing their relative position to one another due to the helical compression spring 41, but rather the clamping tongue 48 by means of the action by the first clamping plunger 22 via the stops 42, 43 clamping the free end 17 of the strapping 9 against the pressure plate 49. The helical compression spring 50, which is weaker than the helical compression spring 41, is compressed. The free band end 17 is thus held between the clamping tongue 48 and the pressure plate 49. Finally, the pair of return rollers 20 is actuated so that the strapping band 9 is pulled out of the band guide channel 16 and placed tightly around the magazine stack 2. This is made possible by the fact that the second clamping plunger 23 is still in the release position, in which its end face is arranged between the two lateral stops 42, 43. The strapping band 9 can thus be carried out freely in the gap 76 formed between this end face, the clamping tongue 48 and the two lateral stops 42, 43.

During the retraction of the strapping 9, the control disk 59 has rotated further, so that the roller 58 finally dips into the control section 65 and the control lever 53 is pivoted further clockwise with respect to FIG. 7 due to the action of the helical compression spring 61. Since the first clamping plunger 22 is already in a stop position, the second clamping plunger 23 is thereby displaced upward relative to the first clamping plunger 22 against the action of the helical compression spring 41 and clamps the strapping section 18 against the clamping tongue 48 with its end face, so that the strapping band 9 is fixed in a taut condition. It should be added that the control drive 40 works non-positively due to the springs 41, 50 and 61, so that a fixing effect occurs regardless of the thickness of the strapping band 9. In the case of thinner strapping straps, the control lever 53 could in the position shown in FIG Swing control section 65, as is made clear by the distance a in Fig. 7 between the roller 58 and the control section 65.

During the control movements of the first and second clamping tappets 22, 23 discussed above, the auxiliary tappet 24 remains in its retracted position, in which the roller 58 'runs along the control section 63'.

The guide plate 67 then moves out of the strapping band sections 25, 26 to be welded in front of the auxiliary tappet 24 and synchronously the welding tongue 74 between these two sections 25, 26 (FIGS. 8, 9). In the meantime, the control discs 59, 59 'continue to rotate, so that the roller 58' of the control lever 53 'dips into the control section 64' and pushes the auxiliary tappet 24 upward. As a result, the two strapping strap sections 25, 26 to be welded are brought into intimate contact with the welding tongue 74, which ensures that these strap sections 25, 26 are heated and inclined. The auxiliary tappet 24 is then briefly pushed back downward by the control section 65 '(FIGS. 10, 11) and the welding tongue 74 is retracted again. Immediately afterwards, the roller 58 'dips into the control section 66' due to the helical tension spring 61 ', as a result of which the control lever 53' is pivoted maximally clockwise and the auxiliary tappet 24 is moved all the way up in the clamping direction K (FIGS. 12, 13). As a result, the two strapping band sections 25, 26 are brought into intimate contact and weld to one another. At the same time, the movable knife jaw 70 moves over the cutting edge 73 of the counter knife jaw 71 and separates the strapping section 26 from the incoming strapping band 9. The strapping of the magazine stack 2 is now complete.

By further rotation of the control disk 59, 59 ', the two control levers 53, 53' are brought back into the starting position shown in FIG. 15, as a result of which the plungers 22, 23, 24 move down again into their release position (FIGS. 14, 15) . At the same time, the clamping tongues 48 and pressure plates 49 move out transversely to the strapping plane U, so that the Strapping 9 is released upwards and the magazine stack 2 on the machine table 5 can be moved out of the belt guide frame 6.

In summary, it is clear from the above explanations that the two clamping plungers 22, 23 can be actuated in a simple manner in terms of construction and control technology by a common control drive 40. A control drive is saved compared to the welding heads according to the prior art. In addition, the welding head 15 is very compact due to the integration of the second clamping plunger 23 in the first clamping plunger 22. Another advantage is that the cutting edge 73 of the cutting device 69 is arranged on the fixed counter knife jaw 71. As a result, the entire width of the movable knife jaw 70 can also weld the straps 25, 26 to be welded. There is therefore no loose, protruding part at the end of the separated strapping section 26. On the other hand, due to the clamping tongue 48, a pull tab that is always the same size and has an optimal length remains at the free end 17.

It should also be added that the pressure plate 49 can be guided optimally so that it is supported securely over at least 3 points, generally over 4 points, during the welding process. The welding point is located at the intersection of the diagonals of the 4 support points, so that, in the long run, parallelism of the pressure plate 49 with the end face of the auxiliary tappet 24 is ensured.

Claims (11)

Device for strapping packaged goods with a strapping band, in particular transverse strapping machine for magazine stacks, comprising: a machine table (5) on which the packaged goods (magazine stack 2) can be moved into and out of the strapping device, an essentially vertical strap guide frame (6) on the machine table (5), in which the strapping strap (9) can be guided as a loose loop around the packaged goods (magazine stack 2), - A shooting and retraction device (14) for shooting the strapping (9) into the strap guide frame (6) and for tightening the strapping (9) around the packaged goods (magazine stack 2), and - A welding head (15) with a clamping device (21) for welding and fixing the strapping band (9) during its retraction, welding and severing from the band supply, the clamping device (21) having a first clamping plunger (22) for fixing the free end (17) of the inserted strapping band (9), a second clamping plunger (23) for fixing the strapping band section (18) overlapping with the free end (17) in the taut state and an auxiliary plunger (24) for acting on the strapping band sections (25, 26) has characterized,
that the second clamping plunger (23) is arranged within the first clamping plunger (22) and is displaceable therein in the clamping direction (K) relative to the latter. Strapping device according to claim 1, characterized in that the first and second clamping plungers (22, 23) are motion-controlled via a single common control drive (40). Strapping device according to claim 1 or 2, characterized by a clamping tongue (48), via which the first clamping plunger (22) presses the free end (17) of the strapped band (9) against a pressure plate (49) in the machine table (5) for fixing. Strapping device according to Claim 3, characterized in that the first clamping plunger (22) has lateral stops (42, 43) on the end face for acting on the clamping tongue (48). Strapping device according to claim 4, characterized in that the second clamping plunger (23) is arranged with its end face in the release position between the two lateral stops (42, 43) and that the strapping band (9) in the clamping tongue (48) between this end face and the two lateral stops (42, 43) formed gap (76) can be carried out freely. Strapping device according to Claim 5, characterized in that the second clamping plunger (23) fixes the strapping band (9) in its clamping position by acting on the clamping tongue (48). Strapping device according to one of Claims 1 to 6, characterized by a control lever (53) to which the second clamping plunger (23) is connected in an articulated manner, which control lever (53) has as a drive a control disk (59) provided with a control cam (62). Strapping device according to claim 7, characterized in that a spring (helical compression spring 41) is arranged between the first and second clamping plungers (22, 23) for transmitting force between the second and first clamping plungers (23, 22). Strapping device according to one of Claims 1 to 8, characterized by a cutting device (69) for separating the welded strapping band (9) from the band supply, the cutting device (69) having a movable knife jaw (70) arranged on the auxiliary tappet (24) and one on a guide part (27) for the auxiliary tappet (24) has stationary counter-knife jaws (71). Strapping device according to claim 9, characterized in that the counter knife jaws (71) has a through opening (72) for the in the welding head (15) has a strapping band (9) which forms the cutting edge (73) of the cutting device (69). Strapping device according to claim 9 or 10, characterized in that the knife jaw (70) is spring-loaded in the direction of the counter-knife jaw (71) (coil springs 78).

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