GB2384483A

GB2384483A - Mortar tub

Info

Publication number: GB2384483A
Application number: GB0300370A
Authority: GB
Inventors: Barry Mccormick
Original assignee: SHIELDTONE Ltd
Current assignee: SHIELDTONE Ltd
Priority date: 2003-01-08
Filing date: 2003-01-08
Publication date: 2003-07-30
Anticipated expiration: 2023-01-08
Also published as: GB0300370D0; GB2384483B

Abstract

A mortar tub for measuring, transporting and storing mortar which is particularly suitable for crane lifting is formed as a moulding of plastic material comprising a base, being substantially rectangular in plan, side walls (10), and a rim (16) surrounding an upper part of the walls (10), the rim (16) having four corner regions, in which at each corner region, a peg (24) is carried on the rim (16), each peg (24) extending generally downwardly whereby the tub can be lifted by a sling of flexible material passed between the pegs (24) and the walls (10).

Description

Mortar tub This invention relates to mortar tubs.

Mortar is often supplied to building sites in a semi-liquid form in containers known as mortar tubs. These tubs are used not only to contain the mortar on a building site, but also to measure the quantity of mortar that is actually delivered. While on site, mortar tubs can encounter an astounding degree of abuse ranging from improper and damaging handling by lifting equipment, to being dropped from a considerable height onto solid ground. Therefore, if it is to function as required throughout a reasonable life span, a mortar tub must be accurately made and extremely durable. For some time, mortar tubs have been constructed from polyethylene, in particular, linear low-density polyethylene (LLDPE) using rotational moulding techniques. While this moulding technique is not fast nor particularly efficient, the products that it produces have very favourable toughness and durability.

There is particular scope for abuse of mortar tubs when they are crane lifted. The applicant has found that all types of unsuitable methods and equipment are pressed into use to crane lift tubs. This results in the tubs being dropped, sometimes from a considerable height, damaging the tub and endangering people working below.

Improper lifting can also cause the tub to be damaged through distortion caused by an inadequately supported load.

Simply providing lifting eyes on a mortar tub is not considered a satisfactory solution. These offer too much scope for use with unsuitable lifting equipment put together from components that are commonly found on a building site.

An aim of this invention is to provide a mortar tub that can be crane lifted easily using simple equipment, but which provides a minimum of opportunity for improper handling.

To this end, this invention provides a mortar tub formed as a moulding of plastic material, comprising a base, side walls, and a rim surrounding an upper part of the walls, the rim having corner regions, in which at each corner region, a peg is carried on the rim, each peg extending generally downwardly whereby the tub can be lifted by a sling of flexible material passed between the pegs and the walls.

This arrangement, it has been found, can provide a tub of that great strength that is easy to lift using the supplied sling. However, it cannot readily be lifted using material such as chains or ropes and that might normally be found on a building site.

Typically, the base is substantially rectangular in plan, there being four such corner regions.

A container embodying the invention may have a capacity of between 100 and 400 litres, and more particularly 200 to 333 litres. A container embodying the invention may be for measuring a quantity of mortar in a commercial transaction, and for subsequent storage of mortar for use on a construction site.

Each peg may be substantially cylindrical, and may be solid. The diameter of each peg may be in the range of 4 to 8 cm (e. g. approximately 5 cm) for a tub of the capacities set forth in the last preceding paragraph. The peg may taper in a downward direction, for example being 5 cm at its upper end, tapering to 4.5 cm at its lower end. A suitable length for each peg is in the range of 10 to 15 cm, for example, 6 cm. The length is selected to ensure that the sling is unlikely to become accidentally dislodged in use while not being so long as to obstruct fitting of the sling.

In typical embodiments of the invention, the rim has an approximately U-shaped cross-section. It typically extends around the entire periphery of the tub. The principal purpose of the rim is to contribute to the strength of the tub. Each comer region upon which a peg is carried may be shaped as a horizontally-projecting boss.

To confer sufficient strength upon the boss, one or more connecting members are advantageously provided, that connect the boss to the adjacent wall. Such

connecting members are advantageously moulded integrally with the boss and the wall.

Advantageously, the pegs can be formed integrally moulded with the tub. This provides a strong tub, and is easy to manufacture.

A particularly preferred form of a mortar tub embodying the invention is a moulding of polyethylene, of preference, linear low-density polyethylene (LLDPE), and most advantageously a rotational moulding of polyethylene. Such mouldings have a particularly advantageous resistance to breakage. Typically, planar parts of the moulding may have a thickness in the range of 7 mm to 11 mm (e. g. approximately 9 mm).

From a second aspect, this invention provides lifting gear for use with a tub embodying the first aspect the invention, the lifting gear comprising two identical slings, each formed from a length of a flexible web material, end portions of the web being folded back on themselves and secured to form a respective loop at each end of the web.

In use, each sling is connected to a crane hook by its end loops, the length of the sling been passed behind a respective pair of pegs of the tub. In this way, the tub can be lifted between the two slings.

From a third aspect, this invention provides a kit comprising lifting gear embodying the second aspect of the invention in combination with one or more mortar tubs embodying the first aspect of the invention.

An embodiment of the invention will now be described in detail, with reference to the accompanying drawings, in which: Figure 1 is a side view of a mortar tub being a first embodiment of the invention; Figure 2 is an end view of a mortar tub of Figure 1; Figure 3 is a view of the tub of Figure 1 from above; Figure 4 is a view of the tub of Figure I from below;

Figures 5 and 6 are detailed views of a corner region of the rim of the tub of Figure 1 ; Figure 7 shows the tub of Figure 1 with lifting gear he in place; and Figure 8 shows, in greater detail, a corner region of the tub width the lifting gear in place.

As shown in the drawings, a mortar tub embodying the invention is formed as a unitary moulding. This embodiment is a moulding of LLDPE formed by a rotational moulding process.

The mortar tub has two opposite side walls 10, two opposite end walls 20 and a base 12 that are arranged to form a volume within which a liquid or semi liquid product can be stored, and which has an upwardly-directed rectangular opening.

Embodiments such as this have a liquid capacity of 250,300 or 333 litres. A typical thickness of the moulding in this application is approximately 9-10 mm, with a total weight of plastic material of 21 kg.

In plan, the base 12 is generally rectangular, and the walls 10,12 extend generally upwardly from its four sides. The walls 10,12 are angled to the vertical such that they taper away gently from one another and outwardly from the periphery of the base 12 towards the opening, thereby allowing similar tubs to be stacked within one another. Additionally, in the event that the contents of the contents solidify, as might happen, for example, if mortar is left in the container for an extended time, the taper of the walls 10,20 helps to ensure that the solid body can always be removed readily. The base 12 is generally flat, with small grooves 14 moulded into it to increase its rigidity. However, it should be noted that the base 12 does not have formations that might allow it to be lifted by way of a forklift. The intention is that this tub should the capable of being lifted by a crane alone, and that tubs specially designed for the purpose should be used if fork-lifting is required.

A strengthening rim 16 is formed at an upper region of each of the walls 10,20. The rim 16 is formed integrally with the walls 10,20 by a region of material that extends outwardly from the upper part of each wall 10,20 that is approximately

shaped as an inverted'U'. Centrally of each end wall 20, the rim 16 has a cut-away section 18 that serves as a lifting handle for the tub.

The rim 16 includes four corner regions at the four intersections between adjacent walls 10,20. At each corner region, the rim 16 is chamfered so that it extends in a direction approximately 45 to the adjacent walls 10,20. From the chamfered region, a boss 22 projects horizontally. In this embodiment, the thickness of the boss 22 is slightly less than the height of the rim and a lower surface of the boss 22 is approximately level with a lower surface of the rim 16. A respective peg 24 projects downwardly from each boss 22. Each peg 24 is substantially cylindrical with a slight taper, having a diameter of approximately 5 cm at the boss and 4.5 cm at its lower end and a length of approximately 6 cm. Each peg 24 is formed as a solid moulding integral with the boss 22 and other parts of the tub.

As shown in figures 7 and 8, lifting gear for the tub comprises two similar slings 30.

Each sling 30 is formed from a length of strong, flexible web material, for example, woven nylon. A loop 32 is formed at the end of each sling by a length at each end of the web folded back upon itself and secured by stitching 34.

In order to lift the tub, the loops 32 of one of the slings 30 are placed over respective pegs 24 at opposite comers of one of the end walls 20, in the configuration shown in Figure 8. The same is done with the other sling 30 at the opposite end wall 20.

As can be seen from Figures 7 and 8, each loop 32 supports the respective boss 22 from below, and is guided by side surfaces of the boss 22.

Mid-points of the two slings 30 can then be brought together over the opening of the tub where they can be hooked in to a crane hook. As the crane hook is lifted, the slings adopt a configuration as shown in at Figure 7, and the container can then be lifted safely. As can be seen, once the weight of the container is borne by the slings, it is most unlikely that the loops 32 will become dislodged from behind the pegs 24.

A moulding tool for use in manufacture of a container embodying the invention comprises two metal shells each having defined within a void shaped as the outer

shape of a container. The shells are joined together at the region that will define the opening of the finished container so that two identical containers can be formed in one moulding operation. Sufficient plastic material in granular form is introduced into one of the mould shells 30. Two shells 30 are then connected to seal the plastic material within a closed void. The assembled shells 30 are then heated to melt the plastic within them to a liquid. Simultaneously, the shells 30 are rotated such that the liquid plastic flows within the void, under the action of gravity, to coat the entire internal surface of the void. Once the heat is removed, the plastic solidifies, creating a moulding of two tubs and joined at their rims.

Claims

Claims 1. A mortar tub formed as a moulding of plastic material, comprising a base, side walls, and a rim surrounding an upper part of the walls, the rim having comer regions, in which at each corner region, a peg is carried on the rim, each peg extending generally downwardly whereby the tub can be lifted by a sling of flexible material passed between the pegs and the walls.
2. A mortar tub according to claim I in which the base is substantially rectangular in plan, there being four such corner regions.
3. A mortar tub according to claim I or claim 2 in which each peg is substantially cylindrical
4. A mortar tub according to any preceding claim in which each peg is solid.
5. A mortar tub according to any preceding claim in which the diameter of each peg is in the range of 5 to 10 cm.
6. A mortar tub according to any preceding claim in which the rim has an approximately U-shaped cross-section.
7. A mortar tub according to any preceding claim in which the rim extends around the entire periphery of the tub.
8. A mortar tub according to any preceding claim in which each comer region upon which a peg is carried is shaped as a horizontally-projecting boss.
9. A mortar tub according to claim 8 in which one or more connecting members are provided, each connecting the boss to the adjacent wall.
10. A mortar tub according to claim 9 in which the connecting members are advantageously moulded integrally with the boss and the wall.

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11. A mortar tub according to any preceding claim in which the pegs are formed integrally moulded with the tub.
12. A mortar tub according to any preceding claim being a rotational moulding of linear low-density polyethylene.
13. A mortar tub according to any preceding claim in which planar parts of the moulding have a thickness in the range of 7 mm to 11 mm.
14. A mortar tub substantially as described herein with reference to the accompanying drawings.
15. A mortar tub substantially as described herein with reference to the accompanying drawings.

15. Lifting gear for use with a tub embodying the first aspect the invention, the lifting gear comprising two identical slings, each formed from a length of a flexible web material, end portions of the web being folded back on themselves and secured to form a respective loop at each end of the web.

16. A kit comprising lifting gear according to claim 15 in combination with one or more mortar tubs according to any one of claims 1 to 14.

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Amendments to the claims have been filed as follows Claims 1. A mortar tub formed as a moulding of plastic material, comprising a base, side walls, and a rim surrounding an upper part of the walls, the rim having comer regions, in which at each corner region, a peg is carried on the rim, each peg extending generally downwardly whereby the tub can be lifted by a sling of flexible material passed between the pegs and the walls.

2. A mortar tub according to claim 1 in which the base is substantially rectangular in plan, there being four such comer regions.

3. A mortar tub according to claim 1 or claim 2 in which each peg is substantially cylindrical 4. A mortar tub according to any preceding claim in which each peg is solid.

5. A mortar tub according to any preceding claim in which the diameter of each peg is in the range of 5 to 10 cm.

6. A mortar tub according to any preceding claim in which the rim has an approximately U-shaped cross-section.

7. A mortar tub according to any preceding claim in which the rim extends around the entire periphery of the tub.

8. A mortar tub according to any preceding claim in which each comer region upon which a peg is carried is shaped as a horizontally-projecting boss.

9. A mortar tub according to claim 8 in which one or more connecting members are provided, each connecting the boss to the adjacent wall.

10. A mortar tub according to claim 9 in which the connecting members are advantageously moulded integrally with the boss and the wall.

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11. A mortar tub according to any preceding claim in which the pegs are formed integrally moulded with the tub.

12. A mortar tub according to any preceding claim being a rotational moulding of linear low-density polyethylene.

13. A mortar tub according to any preceding claim in which planar parts of the moulding have a thickness in the range of 7 mm to 11 mm.

14. A mortar tub according to any preceding claim in combination with lifting gear, the lifting gear comprising two identical slings, each formed from a length of a flexible web material, end portions of the web being folded back on themselves and secured to form a respective loop at each end of the web.