Pre-stretching device and method for inserting packaging film or other sheet material into the pre-stretching device

Abstract

A pre-stretching device (10) and a method for inserting a packaging film or other sheet material into the pre-stretching device, the pre-stretching device being suitable for being installed on a wrapping packaging machine that uses a packaging film (F) (specifically, a stretch film (F) or other sheet material) to wrap a load, the pre-stretching device comprising a support device (11) for a film roll (B) of the stretch film (F), a pair of pre-stretching rollers (13, 14) rotating around respective axes (X1, X2), and a quick insertion device (30) for inserting an edge of the packaging film (F) between the rollers of the pair of pre-stretching rollers (13, 14); the quick insertion device (30) comprising a flexible traction element (17) configured to advance along a path extending between the axes (X1, X2) and partially around them, thereby traction of the edge of the packaging film (F), the edge of the packaging film (F) being connected to the flexible traction element (17) by the rollers of the pair of pre-stretching rollers (13, 14) and a connecting element (20) arranged on the flexible traction element (17).

Description

Technical Field

[0001] The present invention relates to a pre-stretching device and a method for inserting a packaging film or other sheet material into the pre-stretching device. In particular, the pre-stretching device is intended to be installed on a wrapping machine for wrapping a load with a stretch film. Background Art

[0002] Systems for wrapping cargo with stretch film are known to simplify storage and transportation of cargo. For example, a pallet wrapping machine is used to wrap cargo placed on a pallet with stretch film to stabilize the entire structure.

[0003] Before being wrapped around the load, the stretch film undergoes a pre-stretching operation, whereby it is stretched to obtain a considerable elongation, in this way reducing the cost of the material used in the packaging process.

[0004] Specifically, the pre-stretching operation is performed by a pre-stretching device, more specifically, by two motorized rollers arranged side by side and rotating at different speeds (ie, the pre-stretching rollers); specifically, the elongation obtained is a function of the spacing between the two rollers and the speed difference of the rollers.

[0005] However, before operating the pre-stretching device, the stretch film must be inserted between the two rollers. Specifically, a skilled operator manually slides the stretch film between and partially around the two pre-stretching rollers. However, even for a skilled operator, insertion is complex and time-consuming, as the distance between the two rollers is only a few millimeters, a necessary condition for ensuring maximum elongation.

[0006] In order to avoid this disadvantage, some pre-stretching devices have been developed that, in addition to the two pre-stretching rollers, also have an idler roller on a closable cover; in this case, the spacing between the two pre-stretching rollers has been increased to allow the idler roller to be inserted when the cover is closed (operating condition). In this case, the operator no longer needs to manually insert the stretch film between the two pre-stretching rollers, because after closing the cover, the positioning of the idler roller relative to the stretch film is determined, thereby tensioning the stretch film while allowing the stretch film to slide between the two pre-stretching rollers.

[0007] However, this solution not only fails to guarantee satisfactory elongation (specifically, it is lower than the first pre-stretching device described above), but also is more expensive and complex. Furthermore, the lid mechanism requires frequent maintenance to avoid any positioning errors: in fact, even the slightest inaccuracy after closing the lid can affect the performance of the pre-stretching device. In other words, the idler roller actively participates in the delicate pre-stretching process and is therefore a critical component in this type of machine.

[0008] Therefore, there is a need to improve current stretch film pre-stretching devices and also to improve current wrapping machines for wrapping loads with stretch film. In particular, it is desirable to provide a solution that facilitates and speeds up the insertion of stretch film into the pre-stretching device without affecting its performance, while being more affordable and thus significantly reducing maintenance. Summary of the Invention

[0009] An object of the present invention is to improve existing pre-stretching devices for wrapping machines for wrapping and packaging a load with a wrapping film.

[0010] Another object of the present invention is to provide a pre-stretching device that facilitates and accelerates the insertion of the packaging film and is also economically advantageous.

[0011] Yet another object of the present invention is to provide a pre-stretching device that facilitates and accelerates the insertion of the packaging film while ensuring high performance of the pre-stretching device.

[0012] Another object of the present invention is to propose a pre-stretching device that facilitates and accelerates the insertion of the packaging film while limiting periodic maintenance.

[0013] Yet another object of the present invention is to propose a simple and quick method for inserting the packaging film into the pre-stretching device.

[0014] The objects listed above, as well as other objects and advantages, are achieved by a pre-tensioning device and an insertion method according to the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide a further understanding of the present invention and to explain the present invention, but do not constitute a limitation on the implementation of the present invention, wherein:

[0016] Figure 1 is a schematic structural diagram of the pre-stretching device according to the present invention;

[0017] Figure 2 yes Figure 1 A partial enlarged view of the pre-stretching device;

[0018] Figure 3 yes Figure 1 A top view of

[0019] Figure 4 yes Figure 1 A top cross-sectional view of the pre-stretching device after it is inserted into the packaging film;

[0020] Figure 5 yes Figure 1 Another top cross-sectional view of the pre-tensioning device. DETAILED DESCRIPTION

[0021] Referring to the accompanying drawings, the following describes a pre-stretching device 10 suitable for installation in a container that is packed with packaging film F or other paper sheet materials or other suitable materials ( Figure 4 Specifically, the pre-stretching device 10 can adopt a stretch film or an elastic film F. In the following description, in a non-limiting manner and for ease of explanation, only the stretch film F is referenced.

[0022] like Figure 1 As can be seen, the pre-stretching device 10 includes a support device 11 for a film roll B of a stretch film F, a pair of pre-stretching rollers 13 and 14 that rotate about respective axes X1 and X2, and a quick insertion device 30 that inserts the edge of the stretch film F between the rollers of the pair of pre-stretching rollers 13 and 14. In the embodiment shown, the axes X1 and X2 are parallel to each other.

[0023] Specifically, each roller of the pair of pre-stretching rollers 13 and 14 is connected to a respective motor that controls the rotational speed of the pre-stretching rollers 13 and 14 about their respective axes X1 and X2. In practice, in order to stretch the stretch film F, the rollers of the pair of pre-stretching rollers 13 and 14 must rotate at different speeds and must have side surfaces that can exert a sufficiently large friction force on the stretch film F to ensure the necessary clamping force and to ensure that the portion of the stretch film F in contact with the respective rollers of the pair of pre-stretching rollers 13 and 14 advances at the same tangential speed as the same rollers in contact with the stretch film F.

[0024] Specifically, see Figure 2 The quick-insertion device 30 comprises a flexible pulling element 17 configured to advance along a path extending between and partially around the axes X1 , X2 , thereby pulling the edge of the stretched film F through the rollers of a pair of pre-stretching rollers 13 , 14 .

[0025] The quick-insertion device 30 includes a connecting element 20 disposed on the flexible pulling element 17 and configured to connect the edge of the stretch film F to the flexible pulling element 17 .

[0026] exist Figure 2 In the embodiment shown, the connecting element 20 exhibits recesses ( 26 , 27 , 28 ) allowing an operator to securely connect the edge of the stretch film F to the connecting element 20 .

[0027] For example, the flexible traction element 17 can be a rope or tape made of a flexible material. For example, the flexible material can be selected from a combination including polyvinyl chloride, polyester, polyamide or polypropylene.

[0028] At the free end of the flexible pulling element 17 , a gripping element 18 (eg, a handle or grip) is provided, adapted for an operator to grasp and pull in order to advance the flexible pulling element 17 along the path via the pair of pre-tensioning rollers 13 , 14 .

[0029] like Figure 1 and Figure 3 It can be seen that the pretensioning device 10 is further provided with a reset device 23 configured to return the flexible traction element 17 to the rest position; the pretensioning device 10 is provided with a locking element 19 suitable for supporting and receiving the clamping element 18 when the flexible traction element 17 is in the rest position.

[0030] For example, more precisely, the return device 23 may comprise a return spring for rewinding the flexible traction element 17 towards the rest position, in which case the rest position comprises a wound rest position. As an alternative to a passive return spring, the return device 23 may comprise an active return member, such as a winding electric motor, a pneumatic unit, a hydraulic unit or other equivalent active member.

[0031] See also Figure 1 、 Figure 3 and Figure 5 , each pre-stretching roller of a pair of pre-stretching rollers 13, 14 is equipped with a corresponding disc-shaped element 24, 25, each disc-shaped element having a groove in which the flexible traction element 17 slides. Specifically, the disc-shaped element 24, 25 with a groove is placed at one end of the corresponding pre-stretching roller 13, 14.

[0032] For example, the disc-shaped elements 24, 25 having grooves may be two pulleys.

[0033] like Figure 1 and Figure 3 As shown, the pretensioning device 10 is further provided with height adjustment devices 21, 22 to adjust the height of the flexible pulling element 17. Since the flexible pulling element 17 does not need to have a constant height along the entire pretensioning device 10, this configuration has greater design flexibility.

[0034] For example, the height adjustment devices 21 , 22 may comprise pulleys.

[0035] Finally, see Figure 1 、 Figure 3 、 Figure 4 and Figure 5 The pre-stretching device 10 is provided with an input film guide device 12 to guide the stretched film F to be inserted into a pair of pre-stretching rollers 13, 14. For example, the input film guide device 12 may include an idler roller.

[0036] Likewise, the pre-stretching device 10 is further provided with output film guides 15, 16 for guiding the stretched film F to be output from the pair of pre-stretching rollers 13, 14. For example, the output film guides 15, 16 may include idler rollers.

[0037] The following describes the insertion operation of the stretch film F in the pre-stretching device 10 according to the present invention.

[0038] First, the roll B of the stretch film F is inserted into the support device 11, the edge of the roll B is unwound, and then connected to the flexible pulling element 17 via the connecting element 20. For example, the edge of the stretch film F can be firmly connected to the connecting element 20.

[0039] The operator then grasps the gripping element 18 and pulls it; in this manner, the flexible pulling element 17 advances along a path extending between and partially around the axes X1 and X2, drawing the edge of the stretch film F through the pair of pre-stretching rollers 13 and 14. As the flexible pulling element 17 advances, the film roll B unwinds, and the stretch film F is pulled by the flexible pulling element 17, carried along, and inserted between the pair of pre-stretching rollers 13 and 14. The input film guide 12 facilitates the correct insertion of the stretch film F.

[0040] The operator continues pulling until the connecting element 20 passes through both rollers of the pair of pre-stretching rollers 13, 14. In fact, after reaching this point, the insertion of the stretch film F can be considered to be substantially complete because the stretch film F extends between and partially around the rollers of the pair of pre-stretching rollers 13, 14.

[0041] The operator then disconnects the edge of the stretch film F from the flexible pulling element 17 and passes it through the outlet film guide devices 15 and 16, so that the edge of the stretch film F is in the correct position for use in the packaging process. At the same time, the reset device 23 returns the flexible pulling element 17 to the wrapped rest position, which will be maintained until the stretch film F is reinserted by the locking element 19.

[0042] Due to the above-mentioned features, the pre-stretching device 10 allows for comfortable, easy and quick insertion of the stretch film F. The operator no longer needs to perform the inconvenient operation of directly grabbing the edge of the stretch film F with his hands and trying to insert it into the narrow gap between the two pre-stretching rollers, which risks injury. In addition, the quick insertion device 30 according to the present invention does not change the overall structure of the pre-stretching device 10 (for example, the spacing between the rollers of a pair of pre-stretching rollers 13 and 14), so the performance of the pre-stretching device 10 is not affected. At the same time, since the structural configuration of the quick insertion device 30 is greatly simplified, the cost of the pre-stretching device 10 remains very low. In addition, since the quick insertion device 30 according to the present invention is only operated during the stage of inserting the stretch film F, it does not require frequent maintenance; subsequently, it remains stationary during the pre-stretching process.

[0043] As shown above, it is obvious that the pre-tensioning device 10 according to the present invention successfully achieves all the preset goals mentioned above.

[0044] The description and illustrations in the accompanying drawings are provided to illustrate the innovative functions of the pre-tensioning device 10 .

[0045] In practice, the various materials can be appropriately selected according to the requirements and the state of the art, provided they are compatible with the specific application and the respective individual components. Modifications and / or additions may be made to the descriptions and illustrations in the drawings.

Claims

1. A pre-stretching device (10), characterized in that: The pre-stretching device (10) is suitable for being installed on a wrapping machine for wrapping cargo with a packaging film (F). The pre-stretching device (10) comprises a supporting device (11) for a film roll (B) of the packaging film (F), a pair of pre-stretching rollers (13, 14) rotating around respective axes (X1, X2), and a quick insertion device (30). The quick insertion device (30) inserts the edge of the packaging film (F) between the rollers of the pair of pre-stretching rollers (13, 14). The quick insertion device (30) comprises: a flexible pulling element (17) configured to advance along a path extending between and partially around said axes (X1, X2) so as to pull the edge of said packaging film (F) through the rollers of said pair of pre-stretching rollers (13, 14), and a connecting element (20), the connecting element (20) being arranged on the flexible traction element (17), the connecting element (20) connecting the edge of the packaging film (F) to the flexible traction element (17); The pre-stretching device (10) is provided with a height adjustment device (21, 22), and the height adjustment device (21, 22) is used to adjust the height of the flexible traction element (17).

2. The pre-stretching device (10) according to claim 1, characterized in that A gripping element (18) is provided at the free end of the flexible traction element (17), suitable for an operator to grasp and pull so as to advance the flexible traction element (17) along the path through a pair of pre-stretching rollers (13, 14).

3. The pre-stretching device (10) according to claim 2, characterized in that The pre-tensioning device (10) further comprises a resetting device (23) configured to return the flexible traction element (17) to a rest position.

4. The pre-stretching device (10) according to claim 3, characterized in that The pretensioning device (10) is provided with a locking element (19) adapted to support and receive the clamping element (18) in the rest position.

5. The pre-stretching device (10) according to claim 3 or 4, characterized in that The resetting device (23) comprises a return spring adapted to rewind the flexible traction element (17) towards the rest position, including a wound rest position.

6. The pre-stretching device (10) according to claim 3 or 4, characterized in that The reset device (23) comprises an active return component, and the active return component is selected from one of a winding electric motor, a pneumatic unit, and a hydraulic unit.

7. The pre-stretching device (10) according to any one of claims 1 to 4, characterized in that Each of the pre-stretching rollers (13, 14) of the pair is provided with a disc-shaped element, and each of the disc-shaped elements is provided with a groove, in which the flexible traction element (17) is able to slide.

8. The pre-stretching device (10) according to claim 7, characterized in that Each of the disk-shaped elements having the grooves is placed at one end of the corresponding pre-stretching roller.

9. The pre-stretching device (10) according to any one of claims 1 to 4, characterized in that The pre-stretching device (10) is provided with an input film guiding device (12), and the input film guiding device (12) is used to guide the packaging film (F) to be inserted into a pair of pre-stretching rollers (13, 14).

10. The pre-stretching device (10) according to claim 9, characterized in that The input film guide device (12) includes an idler roller.

11. The pre-stretching device (10) according to any one of claims 1 to 4, characterized in that: The pre-stretching device (10) is provided with an output film guiding device (15, 16), and the output film guiding device (15, 16) is used to guide the packaging film (F) to be output from the pair of pre-stretching rollers (13, 14).

12. The pre-stretching device (10) according to claim 11, characterized in that The output film guide device (15, 16) includes an idler roller.

13. The pre-stretching device (10) according to claim 7, characterized in that The flexible traction element (17) is selected from a rope or a tape made of a flexible material.

14. The pre-stretching device (10) according to claim 13, characterized in that The disc-shaped element (24, 25) having the groove comprises two pulleys.

15. The pre-tensioning device (10) according to claim 13, characterized in that The height adjustment device (21, 22) comprises a pulley.

16. The pre-stretching device according to any one of claims 1 to 4, characterized in that: The flexible traction element (17) is selected from the group consisting of polyvinyl chloride, polyester, polyamide or polypropylene.

17. The pre-stretching device according to any one of claims 1 to 4, characterized in that: The connecting element (20) has further grooves (26, 27, 28) allowing the edge of the packaging film (F) to be securely connected to the connecting element (20).

18. A method for inserting packaging film or other sheet material into a pre-stretching device, characterized in that The method comprises inserting a packaging film (F) or other sheet material between a pair of pre-stretching rollers (13, 14) of a pre-stretching device (10) by means of a flexible pulling element (17), and comprises the following stages: The edge of the packaging film (F) is connected to the flexible traction element (17) by a connecting element (20) provided on the flexible traction element (17), Adjusting the height of the flexible traction element (17) by means of a height adjustment device (21, 22) of the pre-stretching device (10); Grasping and pulling a clamping element (18) provided on the flexible pulling element (17), causing the flexible pulling element (17) to advance along a path extending between and partially around the axes (X1, X2) of the pair of pre-stretching rollers (13, 14), thereby pulling the edge of the packaging film (F) through the rollers of the pair of pre-stretching rollers (13, 14), After the connecting element (20) passes through two rollers of a pair of pre-stretching rollers (13, 14), the connection between the edge of the packaging film (F) and the flexible traction element (17) is disconnected.

19. The method according to claim 18, characterized in that The edge of the packaging film (F) is connected to the flexible pulling element (17) via the connecting element (20), comprising firmly connecting the edge to the connecting element (20), and is characterized in that after disconnection, the clamping element (18) is released to the locking element (19), thereby returning the flexible pulling element (17) to a rest position.

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