EP2477898B1 - Tightening strap device for a heat-weldable plastic strip - Google Patents

Description

The invention relates to a strapping device for strapping a package with a thermo-weldable plastic band placed around it, which forms a lower band and a top band at a welding point, with a housing and a device for clamping the plastic band and with a welding plate vibrating relative to the housing for welding the plastic band.

Devices of this type are known, for example from the EP 0 999 132 or the EP 0 949 146 , The plastic band is placed in a loop around a package, wherein a first, free end of the plastic band forms a lower band at a weld and the other end of the plastic band is passed as a top band together with the lower band after formation of the loop at the weld under a weld plate. With a friction wheel or a similar element, the upper band is then grasped and the loop tightened around the package.

So that during this tightening the lower band is not pulled out of the region of the weld, a clamping device is provided with which this sub-band is fixed. This clamping device is usually arranged so that lying in the pulling direction in front of the clamping device, traction-free portion of the plastic strip, which is adjacent to the free end of the plastic strip, is passed through the weld.

At the other end of the loop, the traction-loaded end of the plastic strip is then guided as a top band over the free end of the plastic strip as a sub-band. In this area, in the known device then due to the clamping device traction-free sub-band and due to z. B. a friction wheel traction-loaded upper band firmly compressed by another clamping device.

The plastic band is so wrapped tightly around the package and is in this state at a point where the lower band and upper band parallel to each other, compressed. Here, essentially the upper band is clamped. The lower band is already held by the lower band clamp. The above-mentioned friction wheel is arranged downstream of this clamping point of upper and lower band in the direction of tensile force. If the frictional wheel then no longer applies the frictional and tensile force to the plastic strip, the upper strip is also traction-free in the region of the traction force direction after the nip point.

On this tensile force-free top band a weld plate is then lowered at the weld and vibrated relative to the housing of the strapping. In this case, a toothing is provided between the welding plate and the upper belt of the plastic belt, which transmits the vibrations of the welding plate on the upper belt of the plastic belt. The upper band is therefore also put into a corresponding vibration.

At the same time, the welding plate presses the upper belt against the lower belt, so that due to the vibration of the welding plate or the upper belt between upper belt and lower belt comes to a relative movement, which leads due to the resulting friction to a local melting of the thermoschweißbaren plastic tape.

After completion of the vibration movement and a short period of cooling are then welded together at the weld upper belt and lower belt. It can then be opened on both sides of the weld existing clamping devices for the lower band or for the upper and lower band.

A disadvantage of the method described so far is that the control of the individual clamping and welding elements is relatively complex and thus control technology is a high effort to drive.

Object of the present invention is therefore to simplify a device of the type described above to the extent that it is structurally simple and thus both easier to produce and easier to operate.

This object is achieved in that the already known welding plate in the direction of the plastic strip receives a tensile force against the housing.

The advantage of this invention is that due to this tensile force support, the above-described upper band clamping device, which is normally located immediately adjacent to the weld, may be omitted. Thus, the strapping device according to the invention can be built shorter in the area adjacent to the package. So even smaller packages or packages can be strapped with relatively small diameters.

In particular, the hitherto separate functions of welding plate and clamping element can be made of only one component by such a device. Contrary to previous designs, it is now possible due to the development of the invention, at the same time to use the welding plate as a clamping element to fix with her acting on the plastic band tensile forces.

In a particularly preferred embodiment of the invention, the tensile force support for the welding plate is provided with an acting on the welding plate rolling bearing. As a result, in particular short power lines are possible, so that long power lines are avoided, which would require a correspondingly high torque support.

It has proved to be particularly advantageous to provide the welding plate with a toothing acting in the pulling direction of the plastic strip. This makes it possible to keep the actual weld on the plastic band as before free of tensile forces. The corresponding tensile forces acting in the plastic strip during tightening of the loop are instead transmitted directly to the weld plate on the upper side of the upper strip running in the region of the weld via the toothing. The underside of the under The welding plate passing through the upper belt, where the weld is, is thus free of forces.

Due to the embodiment of the invention so only one means for clamping the plastic strip is present and this acts on the lower band. The upper belt is fixed in place by a clamping device previously provided by the welding plate in the tape direction.

In particular, to achieve particularly short power lines also proposed to integrate the Zugkraftabstützung the welding plate in a stamp, which can be lifted within the housing of the plastic tape and in the direction of this is lowered. While this stamp is relatively stiff and thus made massive, the welding plate can continue to be carried out relatively delicate, so that in their vibration movement only small inertial masses are to be moved. For the drive of the vibrating plate thus a smaller and thus lighter motor can be used, as if the stamp would be moved. Since the strapping devices according to the invention are usually manually traded devices, a corresponding weight saving is advantageous.

So that when raising and lowering the punch, the welding plate is fixed relative to this stamp, it is proposed to let the Zugkraftabstützung attack on one side of the welding plate and to provide on the opposite side a holding element which fixes the welding plate in an axial direction of the punch together with the Zugkraftabstützung ,

With a corresponding construction particularly small and thus compact design embodiments are possible. It is hereby proposed in particular to realize the holding element as well as the tensile force support with rolling elements, which can not only take pure support function. Rather, the corresponding rolling elements can also transmit lateral forces when guided in corresponding rolling tracks. This is for a holder of the welding plate z. B. within a stamp sufficient.

However, the contact pressures to be transmitted between punch and welding plate are preferably transmitted via rolling bearings which are aligned in the direction of the contact pressure. The rolling bearings provided for the tensile force support and the retaining element for the welding plate can therefore be kept free of such loads from such contact pressures.

The stamp, in which the welding plate is held, can either sit in a corresponding guide on the housing or even transmitted by a support arm or the like forces on the housing.

It should be noted that the stamp can also carry a force acting on the upper band, in particular spring-loaded blade, with the welding the process the end of the plastic tape opposite end is severed, so that the weld then connects two free ends of a loop of thermoschweißbarem plastic tape together ,

Figur 1

Seitenansicht eines Umreifungsgerätes;

Figur 2

Detailansicht einer Baugruppe eines Umreifungsgerätes gemäß Figur 1;

Figur 3

perspektivische Ansicht einer Baugruppe gemäß Figur 2;

Figur 4

Schnittansicht einer Baugruppe gemäß Figur 2;

Figur 5

alternative Ausführungsform einer Baugruppe gemäß Figur 2.

Further advantages and features of the invention will become apparent from the following description of an embodiment. It shows

FIG. 1

Side view of a strapping device;

FIG. 2

Detail view of an assembly of a strapping device according to FIG. 1 ;

FIG. 3

Perspective view of an assembly according to FIG. 2 ;

FIG. 4

Section view of an assembly according to FIG. 2 ;

FIG. 5

alternative embodiment of an assembly according to FIG. 2 ,

In FIG. 1 you can see the side view of a strapping device. This has a handle portion 1, which is arranged between a welding portion 2 and a clamping portion 3.

It is also possible to arrange the clamping section and the welding section on the same side of the grip area and not on opposite sides as in the example shown here. The embodiment described here has the advantage of having a more balanced mass distribution, which improves the negotiability of the strapping device.

With such a strapping device, a package 5 is strapped with a plastic strap 4. In the example shown here, the package 5 consists of two cylindrical elements. But it is also possible here plates or stacks of plates, edged rods o. Ä. To strapped.

The plastic tape 4 is passed around the package 5 and then threaded into a strapping machine, with it having a free end 6, as in Fig. 2 can be seen, is placed over a base plate 7 of the strapping device. In the area where the plastic strip 4 runs as a lower band of the base plate 7, it is gripped and fixed by a clamping device 8.

The guided in a loop plastic strip 4 is also performed with a section a second time on the base plate 7, which lies in the tape direction after being led around the package 5. The section of the plastic strip 4, which is guided over the base plate 7 again after being led around the package 5, forms an upper strip 9.

The continuous as upper belt 9 plastic belt is then to the clamping section 3 (see. FIG. 1 ) and passed there under a friction wheel 10. The friction wheel 10 presses the plastic band 4 against a sliding member 11 and pulls the plastic band 4 so tight. The tensile force runs along the plastic strip 4 around the package 5 and is again led out of the plastic strip 4 at the clamping device 8.

In the area above the base plate 7 thus the lower belt 6 is free of traction, while the upper belt 9 absorbs tensile force.

After the friction wheel 10 has tensioned the plastic strip 4 accordingly, in the region of the base plate 7 a welding plate 12 is lowered onto the upper belt 9 and pressed against it.

The welding plate 12 is provided with a toothing 13 on its side facing the upper belt. With this a partially positive, partly non-positive connection of welding plate 12 and upper belt 9 is achieved. At the same time the clamping force on the reibrand 10 is released in order to avoid splicing of the upper belt 9 during the welding and cutting process.

In addition, at the same time the welding plate 12 is placed in a vibration, the vibration direction is transverse to the longitudinal axis of the belt but parallel to its surface orientation.

By this vibration, the upper belt 9 is reciprocated relative to the lower belt 6. In this case, occurs between the underside of the upper belt 9 and the top of the lower belt 6, a friction, which leads there in each case to a local melting of the plastic strip. Thus, the upper belt 9 and the lower belt 6 are welded together in the region between the base plate 7 and weld plate 12 via friction welding.

In the example shown here, the welding plate 12 is on its in the FIG. 2 provided on the left side with a rolling bearing 14. In the example shown here, this is designed in such a way that only forces which are directed essentially parallel to the course of the upper belt 9 and the lower belt 6 are conducted over it.

Thus, the welding plate 12 is provided with a Zugkraftabstützung. Thus, the welding plate 12 can take over the existing teeth on its underside 13 which occur in the plastic band 4 in the region of the loop around the package 5 voltages or the resulting tensile forces. These tensile forces are then passed directly or indirectly into the housing of the strapping device. It should be noted that in the present case under a housing and an internal scaffold o. Ä. Is understood, on which support individual components or components positive and / or non-positively or are fixed or fixed thereto accordingly.

In the present case, the welding plate 12 is mounted in a punch 15, which is displaceable within the housing of the strapping device in a guide is, so that the welding plate 12 is raised or lowered. About the said leadership of the punch 15 of the welding plate 12 in the stamp 15 guided tensile forces are forwarded to the housing of the strapping.

About this punch 15 a pressing force is exerted on the welding plate 12, while as in the FIG. 4 can be seen, via a rocker 16, the welding plate 12 is placed in vibration. - In the FIG. 4 the welding plate 12 is shown in the raised position.

The rocker 16 connects the welding plate 12 in this case with an eccentric drive 17, via which the vibrating motion is generated.

So that the welding plate 12 does not fall out of this upon lifting of the punch 15, in the embodiment shown here, the roller bearing 14 opposite to the welding plate 12, a holding element 18 is provided which is also a rolling element and in corresponding rolling tracks on the punch 15 and at the welding plate 12 is guided. This holding element 18 causes, together with the roller bearing 14, an axial securing of the welding plate 12 within the punch 15.

In order to accommodate the pressure to be transmitted between the punch 15 and the welding plate 12, a roller bearing 20 is also provided, in which the rolling elements run in Wälzbahnen, which are provided on the underside of the punch 15 and on the upper side of the welding plate 12.

Because of this rolling bearing 20, the side of the welding plate 12 provided rolling bearings 14 and 18 are free of lateral forces. This is advantageous for their low wear.

Adjacent to the welding plate 12, a separating knife 21 is provided on the punch 15, which is spring-mounted. This is lowered during the welding process with the punch 15 and by the vibration movement of the upper belt 9 under this cutting knife 21 then the upper belt is severed.

In the FIG. 3 the previously described elements are shown in perspective, in the Figures 2 and 4 are shown in sections. It recognizes the packages 5, which are strapped with the plastic strip 4. The free end of the plastic strip 4 is taken as a lower band 6 of the clamping device 8.

The lower belt then runs together with the upper belt 9 on the base plate 7 and is there by the welding plate 12 vibrated. In this case, the welding plate 12 is guided in a punch 15 and is reciprocated in this by a rocker 16.

The welding plate 12 is thereby secured against falling out of the punch 15 via a holding element 18 designed as a rolling bearing, together with a roller bearing 14 which also acts as a traction support. The pressure forces transmitted by the punch 15 to the welding plate 12 are transmitted via a rolling bearing 20.

Furthermore one recognizes in the FIG. 3 on the stamp 15 or with this in a lowerable band guide 22. A on the FIG. 3 not to be recognized further tape guide is provided on the other side of the belt 4 on the punch 15.

With these tape guides the plastic tape 4 is adjusted at the point where it runs under the punch 15, so that the upper and lower belt exactly superimposed. Thus, a correct welding and a correct separation of the upper band are possible.

Once the punch 15 has been lowered, the tape guides 22 are raised so that the upper belt 9 can be vibrated freely.

In the FIG. 5 an alternative embodiment for a stamp is shown. The same parts are provided with the same reference numerals.

While in the embodiment described so far, the punch 15 via a form-fitting sleeve-like guide within the housing of a strapping device is conducted in the FIG. 5 proposed a support of the punch 15 via a support arm 23. About this support arm 23 from the top band 9 registered on the welding plate 12 by the roller bearing 14 in the punch 15 tensile forces are introduced into the housing 24 of the strapping device and thus supported. The support arm 23 is connected via respective axes 25 and 26 with the punch 15 or the housing 24.

Claims (9)

1. A strapping device for strapping a package (5) with a thermally weldable plastic strip (4) placed around it including a housing (24) and a device (8) for clamping the plastic strip (4) and a welding plate, which vibrates with respect to the housing (24), for welding the plastic strip (4), characterised in that in the direction of the plastic strip the welding plate (12) has a tensional force support with respect to the housing.
2. A strapping device as claimed in Claim 1, characterised in that the tensional force support includes a roller bearing (14).
3. A strapping device as claimed in Claim 1, characterised in that the welding plate (12) includes toothing (13) in the tensional direction of the plastic strip (4) cooperating with the latter.
4. A strapping device as claimed in Claim 1, characterised in that the device (8) for clamping the plastic strip acts on a section of the plastic strip (4) acting as a lower strip and a section of the plastic strip acting as an upper strip (9) is fixed in position in the direction of the strip by the welding plate (12).
5. A strapping device as claimed in Claim 1, characterised in that the welding plate (12) is mounted in a plunger (15), which is lowerable within the housing (24) onto the plastic strip (4) and is liftable from below.
6. A strapping device as claimed in Claim 5, characterised in that the tensional force support (14) engages one side of the welding plate (12) and provided on the opposite side there is a retaining element (18), which, together with the tensional support (14), retains the welding plate (12) in the plunger (15).
7. A strapping device as claimed in Claim 5, characterised in that between the plunger (15) and welding plate (12) there is a roller bearing (20), which transmits a contact pressure.
8. A strapping device as claimed in Claim 5, characterised in that between the plunger (15) and housing (24) there is a support arm (23).
9. A strapping device as claimed in Claim 5, characterised in that fastened to the plunger (15) there is a cutting blade (21) acting on the upper strip (9).

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