GB1593655A

GB1593655A - Stackable crate

Info

Publication number: GB1593655A
Application number: GB41340/77A
Authority: GB
Original assignee: NORPLASTA AS
Current assignee: NORPLASTA AS
Priority date: 1976-10-14
Filing date: 1977-10-05
Publication date: 1981-07-22
Also published as: NO763494L; NO139044B; DK407177A; SE7710625L

Description

(54) IMPROVED STACKABLE CRATE (71) We, NORPLASTA A/S, a Company of Norway, of N-7500 Stjordal, Norway, do hereby declare this invention f6r which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to stackable crate formed from or composed of a synthetic plastics material.

Increasing prices for plastic raw material and the desire for easy handling have led to a need for material-saving crate constructions. In crates for stacking this has led, inter alia, to a type of crate having reinforcing ribs which extend in the height direction of the crate. Such ribs will increase the counter-moment of the wall of the crate about an axis through the wall parallel to the base plane. In this way, breakage of the crate about this axis is prevented. In those instances where the crate is designed for the reception of identical objects of long-narrow shape, such as bottles flasks and the like, the reinforcing ribs can be spacers utilised at the same time as base reinforcers or strengtheners. They are connected then to an inner lattice or grille which is anchored in the base of the crate, at least at individual locations.

The counter-moment of the wall of the crate about a vertical axis is not, however, substantially influenced by such vertical reinforcing ribs. The joining of the reinforcing ribs to the lattice will certainly increase the counter-moment about the vertical axes but such a lattice will, as a rule, only be able to extend over the lowermost portion of the height of the crate. This applies especially to crates for use in retail consumption of goods, for example, mineral waters and the like, where regard for easy withdrawal has a big influence on design. In such instances, the walls of the known crates are afforded relatively little strength against bending about a vertical axis. The desire to give the crates the largest possible use volume prevents an effective strengthening of the edge of the crate so as to reduce a possible tendency to bending.Certain of the strengthening means which have been utilised, for example, reinforcing ribs parallel to the base on the exterior of the wall of the crate, have been unacceptable for hygienic and to a certain degree for aesthetic reasons.

There is clearly a need to improve the wall strength of the known crate without giving up any of the advantages thereof.

According to the present invention there is provided a stackable crate formed from or composed of a synthetic plastics material and which comprises at least one reinforcing rib extending vertically along each of two opposite walls, said crate being such that when stacked with another similar crate on top thereof, the ribs are engaged initially by the overlying crate and are deformed until a stacking seat on the underside of the upper crate engages a supporting seat of the lower crate so that the support of the load of the upper crate is shared by said ribs and said supporting seat.

When such a crate is stacked above another crate of the same kind, there will be formed thereby an abutment initially against the vertical reinforcing ribs. First of all, after these reinforcing ribs are deformed under the weight of the overlying crate, that is to say pressed together until the dimensional difference is balanced, and with this have accepted a portion of the weight of the uppermost crate, there will be a transfer of the weight loading to the crate wall. The reinforcing ribs will, in this way, receive a pressure force in the longitudinal direction in addition to the bending moment which acts from the crate wall. In this way the strength characteristics of the reinforcing ribs are able to be utilised completely.

A stacking crate designed in accordance with the invention can, therefore, endure a greater vertical axis moment loading than corresponding known crates, that is to say several overlying crates and/or heavier contents in these.

In a crate having a rectangular base, the invention can, in principle, be utilised with such a reinforcing rib at each longitudinal side, However, in practice, two or more such reinforcing ribs at each longitudinal side will be provided.

In order that the invention can be more clearly understood, a convenient embodiment thereof will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a crate, and Figure 2 is a vertical scrap section through two similar crates each as shown in Figure 1, when stacked above one on the other.

Referring to Figure 1, the crate has a rectangular base and consequently two longitudinal walls 11 and two short walls 12.

The wall surfaces are closed with the exception of a grip opening 13 in each short wall.

Outside the handling areas, upper edges of the walls 11 and 12 of the crates are designed with a short downwardly depending flange 14 on the outside. At the transitions between the sides the crate has hollow corner columns 15 and strengthening and seating ribs 16 which also form drains open downwards towards the base plane of the crate. Between the flange 14 at the upper edge, and the strengthening and seating rib 16 and the respective wall portions, there are arranged webs 17 which make these portions more rigid.

Along the base 18 of the crate, there extends along the edge a low rib 19 which is spaced inwards somewhat from the plane and by which the crate can seat on an underlying crate when stacked therewith.

In the interior of the crate, there is present a lattice of longitudinal and transverse vertical rib walls 21 and 22 respectively which extend over about 1/3 of the height of the crate. There are present five longitudinal ribs and seven transverse, but these numbers can naturally vary depending upon the size and function of the crate.

The two outermost of the longitudinal separating walls 21 have extensions in the form of upwardly projecting ribs at the short walls 12, one on each side of the handling opening 13. Correspondingly, the transverse separating walls 22 have extensions in the form of reinforcing ribs 23 at the longitudinal walls 11. The reinforcing ribs 23 extend outwardly of the wall by an amount which diminishes from about half a cage width at the bottom upwards towards the top, where this extension is reduced to about one half.

The tops of the reinforcing ribs 23 define an abutment surface 24 which on stacking is engaged by the under edge of the rib 19 spacing the step 20 and the bottom of ribs 16 from the top of the underlying crate by the distance Ah,. The weight of loaded crate causes the rib extensions to deform so that the weight of the loaded crate is not only transferred through abutment between the rib 19 and the reinforcing ribs 23, but also by virtue of ribs 16 engaging the top edge of the lower crate in the region of flange 14.

The distance in the direction of height between the under edge of the rib 19 and the underside of ribs 16 is slightly greater than the distance in the same direction between the surface 24 and the upper edge of the crate. This dimensional difference, which in Figure 2 is designated as stated by Ah, is selected to be so small that it corresponds to the deformation which takes place between the rib 19 and the rib 23 on a loading which corresponds to a certain proportion of the weight of a filled crate. In this way, there can be obtained a weight distribution between the edge of the crate and the reinforcing ribs 23 so that the reinforcing ribs are load-supporting on stacking. This pressure loading will then come in addition to the moment which operates on the reinforcing rib 16. In practice, the dimensional different Ah is chosen to be less than 0.5 mm.In an embodiment where the crate is made of polypropylene, a dimensional difference of 0.2mm has proved to be satisfactory.

WHAT WE CLAIM IS: 1. A stackable crate formed from or composed of a synthetic plastics material and which comprises at least one reinforcing rib extending vertically along each of two opposite walls, said crate being such that when stacked with another similar crate on top thereof, the ribs are engaged initially by the overlying crate and are deformed until a stacking seat on the underside of the upper crate engages a supporting seat of the lower crate so that the support of the load of the upper crate is shared by said ribs and said supporting seat.

2. A crate according to claim 1, wherein crate is designed so that said deformation is less than 0.5mm.

3. A crate according to Claim 2, wherein crate is designed so that deformation is about 0.2mm.

4. Crates as claimed in claim 1 and constructed substantially as described herein with particular reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. greater vertical axis moment loading than corresponding known crates, that is to say several overlying crates and/or heavier contents in these. In a crate having a rectangular base, the invention can, in principle, be utilised with such a reinforcing rib at each longitudinal side, However, in practice, two or more such reinforcing ribs at each longitudinal side will be provided. In order that the invention can be more clearly understood, a convenient embodiment thereof will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a crate, and Figure 2 is a vertical scrap section through two similar crates each as shown in Figure 1, when stacked above one on the other. Referring to Figure 1, the crate has a rectangular base and consequently two longitudinal walls 11 and two short walls 12. The wall surfaces are closed with the exception of a grip opening 13 in each short wall. Outside the handling areas, upper edges of the walls 11 and 12 of the crates are designed with a short downwardly depending flange 14 on the outside. At the transitions between the sides the crate has hollow corner columns 15 and strengthening and seating ribs 16 which also form drains open downwards towards the base plane of the crate. Between the flange 14 at the upper edge, and the strengthening and seating rib 16 and the respective wall portions, there are arranged webs 17 which make these portions more rigid. Along the base 18 of the crate, there extends along the edge a low rib 19 which is spaced inwards somewhat from the plane and by which the crate can seat on an underlying crate when stacked therewith. In the interior of the crate, there is present a lattice of longitudinal and transverse vertical rib walls 21 and 22 respectively which extend over about 1/3 of the height of the crate. There are present five longitudinal ribs and seven transverse, but these numbers can naturally vary depending upon the size and function of the crate. The two outermost of the longitudinal separating walls 21 have extensions in the form of upwardly projecting ribs at the short walls 12, one on each side of the handling opening 13. Correspondingly, the transverse separating walls 22 have extensions in the form of reinforcing ribs 23 at the longitudinal walls 11. The reinforcing ribs 23 extend outwardly of the wall by an amount which diminishes from about half a cage width at the bottom upwards towards the top, where this extension is reduced to about one half. The tops of the reinforcing ribs 23 define an abutment surface 24 which on stacking is engaged by the under edge of the rib 19 spacing the step 20 and the bottom of ribs 16 from the top of the underlying crate by the distance Ah,. The weight of loaded crate causes the rib extensions to deform so that the weight of the loaded crate is not only transferred through abutment between the rib 19 and the reinforcing ribs 23, but also by virtue of ribs 16 engaging the top edge of the lower crate in the region of flange 14. The distance in the direction of height between the under edge of the rib 19 and the underside of ribs 16 is slightly greater than the distance in the same direction between the surface 24 and the upper edge of the crate. This dimensional difference, which in Figure 2 is designated as stated by Ah, is selected to be so small that it corresponds to the deformation which takes place between the rib 19 and the rib 23 on a loading which corresponds to a certain proportion of the weight of a filled crate. In this way, there can be obtained a weight distribution between the edge of the crate and the reinforcing ribs 23 so that the reinforcing ribs are load-supporting on stacking. This pressure loading will then come in addition to the moment which operates on the reinforcing rib 16. In practice, the dimensional different Ah is chosen to be less than 0.5 mm.In an embodiment where the crate is made of polypropylene, a dimensional difference of 0.2mm has proved to be satisfactory. WHAT WE CLAIM IS:

1. A stackable crate formed from or composed of a synthetic plastics material and which comprises at least one reinforcing rib extending vertically along each of two opposite walls, said crate being such that when stacked with another similar crate on top thereof, the ribs are engaged initially by the overlying crate and are deformed until a stacking seat on the underside of the upper crate engages a supporting seat of the lower crate so that the support of the load of the upper crate is shared by said ribs and said supporting seat.