GB2340195A

GB2340195A - Strapping tool

Info

Publication number: GB2340195A
Application number: GB9816933A
Authority: GB
Inventors: Tony Sandland
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-08-04
Filing date: 1998-08-04
Publication date: 2000-02-16
Also published as: GB9816933D0

Description

2340195 SMAPPING TOOL The present invention relates to tools for applying

strapping material to packages and the like, and in particular to tools for applying closure devices such as seals or clips to the ends of the strapping material to secure the ends together and thus the strapping material around a package.

The use of plastics materials such as polyester, nylon and the like, and also, more generally, of non-metal corded or woven materials, for forming strapping bands has become widespread in the last thirty years or so. In many applications, these strapping bands have replaced or become a useful alternative to the traditional metal bands, for securing boxes, crates and other articles in a closed condition, or securing them to pallets.

The present invention relates particularly to the use of non-metal, flexible strap formed of plastics and/or other woven materials, and will be referred to throughout the present specification as "strapping material" or "strap" - To effect a strapping operation, a strap tensioning tool is normally used, which performs at least the following basic functions:

(i) retention of a (first) free end of the strap; (ii) gripping of the other (second) free end of the strap generally in overlying relation to or close proximity to the first free end, often while the second free end is still attached to a reel of -- strapping material; (iii) tightening of the second end relative to the first end; and I (iv) attachment or affixing of a closure device to secure the first and second ends of the strap together while they are under tension.

Numerous examples of strap tensioning and sealing tools are known in the art. Particular examples of these can be found in UK Patent Application No. 9803849.0 and US Patent No. 4,056,128, both of which apply compression seals to overlying strap ends as closure devices.

The use of a strap tensioning tool is particularly important when using plastic strapping material, and other woven types of strap, since they are inherently somewhat elastic and the closure device must be applied while the strap is under a degree of tension in order to achieve a satisfactory tightness of strap around a package.

However, existing strap tensioners are primarily designed for use on flatsided packs in which the flat sides are sufficiently long to accommodate the length of the strap tensioner therealong and the packs are of sufficient peripheral length such that the natural elasticity of the strap takes up any slack caused by removal of the tool from under the strap after tensioning and securing of the closure device.

Figure I illustrates a particular problem which arises when strapping circular or curved sided packages, such as when strapping bundles of elongate objects together.

A strap tensioner I is shown schematically and includes a base plate 2 which normally lies against the side of a package 15 being strapped. A gripper foot 3 clamps a first free end 10 of the strap I I to the upper surface of the base plate 2. A strap capstan 4 has a slot 5 into which the m second free end 12 of the strap 11 is threaded - Rotation of the capstan 4, by use of a handle of the strap tensioner 1, tightens the overlying ends 10, 12 of the strap 11 such that a sealer and cutter mechanism 6 can secure the first and second ends together using an appropriate closure 5 device, and cut the second end from the remaining part of the strap reel (not shown). The sealer mechanism may form a part of the front end of the tool 1 adjacent the cutter mechanism 6 or may be provided separately in front thereof.

After securing the strap with a closure device, the strap tensioner 1 can be slid out from the secured strap sideways, ie. into the plane of the drawing. With a normal, flat sided package, the amount of slack generated when the strap tensioner 1 is removed is negligible.

However, the prior art strap tensioners often do not operate satisfactorily on round packages or bundles 15 because the length and thickness of the base plate 2 lying between the strap 11 and the sides of the package 15 as shown in the schematic of figure I is often too great. The natural elasticity of the strap I I is insufficient to compensate for the reduction in peripheral length which occurs when the tensioner 1 is removed. The smaller the radius of curvature of the package 15, the greater the problem.

It is an object of the present invention to provide a strap tensioning tool for use with packages having circular or curved faces.

It is a further object of the present invention to provide an adaptor for converting conventional strap tensioning tools for use on packages having circular or curved faces.

3 According to one aspect, the present invention provides a strap tensioning tool for use with a self-locking buckle comprising:

a base plate foot for receiving a self-locking buckle thereover, the foot having a toe portion adapted for engagement beneath a lower leading arm of the buckle and a bearing surface adapted for engagement with an upper leading arm of the buckle; a tensioning device, situated to the rear of the base plate foot, for tensioning strap passing through the buckle.

According to another aspect, the present invention provides an adaptor for a strap tensioning tool comprising:

a base plate foot for receiving a self-locking buckle thereover, the foot having a toe portion adapted for engagement beneath a lower leading arm of the buckle and a bearing surface adapted for engagement with an upper leading arm of the buckle; and an extension plate for mounting the base plate foot forwards of the strap tensioning tool.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows a schematic diagram of a prior art strap tensioner in use for strapping a circular cross-section package or bundle;

Figure 2a shows a plan view of a modified strap tensioning tool according to one embodiment of the present invention; Figure 2b shows a side view of the modified strap tensioning tool of figure 2a, and a perspective view of an industry standard buckle for use therewith; 4 Figure 3a shows a schematic side view of the modified strap tensioning tool of figure 2a, in use with a circular cross-section package with strap and buckle in place; Figure 3b shows a detailed schematic side view of a portion of the adaptor of the strap tensioning tool of figure 2a, with strap and buckle in place; Figure 3c shows a schematic diagram of a side view of the buckle of figure 2b with strap travel path illustrated; and Figure 4 shows a detailed side view of an alternative embodiment of foot for the tool of figures 2 and 3.

Figure I has already been discussed in detail with reference to the prior art. With reference to figures 2a and 2b, there is shown a strap tensioning tool 20 according to a preferred embodiment of the invention.

In this preferred embodiment, the strap tensioning tool 20 includes a standard strap tensioner 21 to which is coupled an adaptor 40 to be described hereinafter. However, it will be understood that the strap tensioning tool 20 could be manufactured as an integral unit.

The strap tensioner 21 comprises a base plate 22, a strap capstan 24 with a slot 25 into which a free end of strap can be threaded. Rotation of the capstan 24 by use of a handle 27 is effected by a ratchet and pawl mechanism (not shown) as is well known in the art. A rotary cutter mechanism 26, such as that described in UK Patent Application No.

9803849.0 may also be provided. A gripper foot 23 for clamping a free end of the strap to the base plate 22 may also be found on conventional tensioners 21: however, with the present invention, this gripper foot becomes redundant and can be omitted.

Projecting forwards from the strap tensioner 21 is an adaptor 40 which comprises an extension plate 41 which is secured to the existing base plate 22 of the tensioning tool 21. Other methods of securing the adaptor 40 to the strap tensioner 21 are, of course, possible. Carried by the extension plate 41 is a foot 43 specially adapted to receive a closure device for connecting together the two free ends of strapping material.

In the preferred embodiment, the closure device is an industry standard buckle 60 as shown in figure 2b. The extension plate 41 preferably extends both forwards and upwards from the body of the tensioner 21, so that the foot 43, extending generally downwards from the extension plate 41, does not project significantly below the plane of the base plate 22, if at all.

Throughout the present specification, the tensioning tool 20 is described using the expressions "forward end" or "leading end" to describe the end closest to the foot 43, while the expressions "rear" or "trailing end" refer to the end nearest to the gripper foot 23. The expressions "upper" and "lower" are used in the context of a typical orientation of use as shown in figures 2 and 3. Such expression are used for convenience and are not otherwise limiting.

The standard buckle 60, as shown in figure 2b comprises an upper leading arm 61, a lower leading arm 62, an upper trailing arm 64 and a lower trailing arm 63. The conventional path for the strap 11 to take through the buckle is shown in figure 3, particularly figure 3c which shows the buckle 60 before the strap 11 passing therethrough has been tensioned.

6 It will be understood that the buckle 60 is of the self-locking type such that passage of the leading end 65 of the strap 11 behind the lower leading arm 62, around the upper leading arm 61 and again behind the lower leading arm 62 causes the buckle 60 to close when the strap 11 is tensioned. The friction generated by the clamping action of the upper and lower leading arms 61, 62 maintains the strap tension and thereby holds the buckle closed. A corresponding action takes place with the trailing end 66 of the strap 11 as it passes in front of the lower trailing arm 63, around the upper trailing arm 64 and back down in front of the lower trailing arm 63.

The foot 43 has a length and a width sufficiently small that a toe portion 50 and heel portion 51 of the foot 43 can pass through the buckle 60. The toe portion 50 includes an upper surface 52 on which the lower leading arm 62 rests. The foot 43 also includes an upper bearing surface 53 against which the upper leading arm of the buckle rests.

In the preferred embodiment shown, the upper bearing surface 53 also bears down on the upper leading arm 61 to assist in closure of the buckle 60. Preferably, the foot 43 includes a smoothly curved concave front surface 55 which defines the toe portion 50 surface and the bearing surface 53 to assist the closure of the buckle 60 when the strap 11 is tensioned from the rear of the foot 43.

In another embodiment, as shown schematically in figure 4, the toe portion 50 and bearing surface 53 of the foot 43a may include initial leading horizontal faces 57, 58 which are opposed to one another to provide for retention of a buckle 60 when initially installed and prior to tensioning.

7 The length of the foot 43, between heel and toe may be less than 10 mm to accommodate an industry standard buckle size. In this arrangement, as shown in figure 3b, less than 10 mm length of footprint or sole 56 of the foot 43 resides between the buckle 60 and the package 15 being strapped. Thus, there is virtually no or minimal loss of tension when the tensioning tool 20 is removed.

In use, the strap 11 is threaded through the buckle 60 and around the package 15 so that the leading and trailing ends 65, 66 of the strap I I are positioned as shown in figures 3a and 3c. The trailing end 66 of the strap 11 is also fed laterally into the slot 25 of the capstan 24. The buckle 60 is installed onto the foot 43 with its leading arms 61, 62 lodged into the cavity defined by the concave front surface 55 of the foot 43, as defined by toe portion 50 and bearing surface 53.

The strap tensioner 20 is operated by handle 27 to draw the trailing end 66 of the strap 11 backwards. The tightening of the strap 11 draws together upper and lower leading arms 61, 62 and also upper and lower trailing arms 64, 63 as discussed above.

The curvature of the front face 55 of the foot 43 assists this action and ensures that the leading arms 61, 62 close and lock securely before the final locking of the trailing arms 63, 64 by the trailing end 66 of strap being operated upon by the tensioning capstan 24.

Once the strap is secured, the handle 27 is depressed to actuate the cutter 26 and cut the trailing end 66 of the strap. The strap 11 can then be laterally slid out of the slot 25 of the capstan 24 and the tensioner foot 8 43 can be lifted out of the buckle 60, if necessary by a slight anticlockwise rotation of the tensioning tool 20 as viewed in figures I and 2.

Various modifications may be made to the embodiments described above. For example, the foot 43 may include a "quick fit" attachment mechanism so as to be readily interchangeable to accommodate different gauges of buckle. The "quick fit" attachment mechanism may be between the adaptor plate 41 and the base plate 22.

The profile of the front surface 55 of the foot may be any suitable profile to ensure that the leading arms 61, 62 of the buckle can be drawn together upon tensioning of the strap 11.

Embodiments of the foot have been demonstrated to operate satisfactorily on packages as small as 25 min diameter using standard buckles.

9

Claims

I A strap tensioning tool for use with a self-locking buckle comprising:

a base plate foot for receiving a self-locking buckle thereover, the foot having a toe portion adapted for engagement beneath a lower leading arm of the buckle and a bearing surface adapted for engagement with an upper leading arm of the buckle; a tensioning device, situated to the rear of the base plate foot, for tensioning strap passing through the buckle.
2. A strap tensioning tool according to claim 1 in which at least a portion of the bearing surface is angled to some extent toward the toe portion.
3. A strap tensioning tool according to claim 2 in which the bearing surface and toe portion extend toward one another so as to co-operate to assist closure of the upper and lower leading arms of a buckle as the buckle is drawn in a rearward direction.
4. A strap tensioning tool according to claim 2 or claim 3 in which the toe portion and the bearing surface include retention means for holding an unfastened buckle in place prior to a strap tensioning operation.
5. A strap tensioning tool according to any preceding claim in which the base plate foot includes a heel face which resides between the leading and trailing arms of the buckle.
6. A strap tensioning tool according to claim 5 in which the base plate foot includes a sole length between the toe and heel of less than 10 MIM.
7. A strap tensioning tool according to any preceding claim in which the base plate foot is mounted on an extension plate which projects forward from a strap tensioning mechanism.
8. A strap tensioning tool according to claim 7 in which the extension plate projects forwards and upwards from the base of a strap tensioning mechanism.
9. An adaptor for a strap tensioning tool comprising: a base plate foot for receiving a self-locking buckle thereover, the foot having a toe portion adapted for engagement beneath a lower leading arm of the buckle and a bearing surface adapted for engagement with an upper leading arm of the buckle; and an extension plate for mounting the base plate foot forwards of the strap tensioning tool.
10. An adaptor according to claim 9 in which the extension plate is adapted for mounting the base plate foot forwards and upwards from a base plate of the strap tensioning tool.
11. A strap tensioning tool substantially as described herein and with reference to the accompanying drawings figures 2a to 4.
12. An adaptor for a strap tensioning tool substantially as described herein and with reference to the accompanying drawings figures 2a to 4.