Cases and methods of manufacturing them

Abstract

 A method of making an instrument case lid or body from sheet material such as steel or toughened aluminium, in which a sheet (1) of the material is bent to form the base and sides of the body together with a flap (4) at each end of each side turned inward at an acute angle, and a corner member (5) so shaped as to engage the flaps and to completely enclose the corner on all sides is applied at each corner, the corner of the sheet being cut away to enable the corner member to be slid over the flaps from the outside of the lid or body, and the corner member being secured in position by a fastener passing through the base.
The corner members members are preferably of metal, but may be of plastic, and they may be in one piece, or consist of separate parts.

Description

[0001] The invention is concerned with the manufacture of cases of the type used for transporting and storing delicate articles such as scientific instruments, electronic and optical equipment and the like. Such cases are of robust construction, usually being fabricated from metal sheets, such as plastic-coated steel, stainless steel or cold-rolled aluminium alloy by welding, although certain thermo-forming plastics and heavier grades of fibreboard are also suitable. The edges and corners may be reinforced with metal strips riveted or welded into place. Usually a rubber sealing lip or gasket is provided at the edges of the case body and lid to seal the case against the ingress of dirt and moisture, and cam-operated locks may be provided to ensure tight closure. Locks and/or handles may be recessed to protect them from damage, and for convenience in stowage in the cargo holds of ships and aircraft. The cases are generally fitted with resilient inserts, for example of plastic foam, to hold the contents in place without damage. The case may be provided with feet, and corresponding recesses may be formed in the lids to facilitate stacking the cases on top of one another, Patent application GB 2 012 242 A describes a method of making lidless open trays, especially trays for storing fruit and vegetables, very cheaply, and from intrinsically weak materials such as cardboard. In this method a sheet is cut and folded and the sides are engaged by a length of plastic extrusion of suitable cross-section. The method does not yield a robust construction, or one which could readily be made weather-­resistant.

[0002] Examples of the present invention, which is defined in the claims appended hereto, will now be described with reference to the accompanying drawings, in which

Figure 1 comprises fragmentary views of one corner of a metal sheet, showing how it is cut and bent to form a corner of a case,

Figure 2 comprises a longitudinal section and an end view of a corner member formed from sheet metal,

Figure 3 comprises longitudinal and cross sections of corner members formed as a plastic injection moulding,

Figure 4 shows, by means of a cross-section and broken-away views, the details of a corner formed with a two-element corner member, and

Figure 5 shows, in axial section, a pair of rivets which may be used in combination to fasten the case corners and at the same time provide protective feet for the cases and aid in their stacking.

[0003] Referring first to Figure 1, a sheet 1, which may be of steel, is cut to form the bottom and sides of a case of strong construction, such as is used, for example, for transporting delicate instruments. Alternative materials may be used, provided they are sufficiently tough and will hold their shape, for example toughened aluminium, heavy gauge fibreboard or certain thermo-forming plastics. The re-entrant corners of the cut sheet are then further cut away to form notches, 2, as shown at (a) of Figure 1. These notches, as will be explained, will allow a corner member forming a closed corner to be fitted from the outside of the case, where, for preference, it may be sealed to the sides of the case to form a seal which is at least sufficiently watertight to prevent rainwater entering. A rivet hole, 3, is provided for the rivet which will secure the corner member in place. The inner corner of the notch may be rounded as shown at (d).

[0004] The edges of the sheet at the cut-away corners are then bent upwards in a pressing and forming operation and turned inwards at the dotted lines through an angle of preferably rather greater than 45° to form flaps 4. The sides are next bent upwards to form the body of the case, the flaps 4 then projecting inwards, where they lie adjacent and diverging from one another, as shown in plan at (b), and in elevation at (c).

[0005] The corners of the case are now formed by sliding a corner member on to each corner, the notches 2 referred to above providing an opening which allows this to be done from the outside in such a way as to seal the corner. One form of such a corner member is shown in Figure 2.

[0006] This figure shows a longitudinal section (a) and an end view (b) of a corner member fabricated from sheet metal, for example, steel. It consists of a pressing 5, rounded to conform to the shape of the corner, with the end curved over to form a flange 6. On the inside of the pressing 5 a shaped metal section 8 is spot-­welded into place. This is corrugated into a zig-zag form in cross-section, the shape being so designed as to engage and firmly grip the inward-bent flaps 4 of the sides of the case.

[0007] To assemble the case a corner member is slid on to each corner. This is rendered possible by the notches, which provide the openings at the corners through which the corner members may be slid into place from the outside of the case. When the corner members are in position they cover these openings and provide an intact outer surface. They are finally fastened in place by a rivet through the bottom hole. The flaps of the bent-up sides are locked into place within the corner members, forming a rigid structure.

[0008] When assembled, the flange 6 of each corner lies snug against the outside of the bottom of the case and the other two sides of the corner member lie against the side walls of the case. These joints may be sealed with mastic or other suitable material to render the case weatherproof. A hole 7 is provided for a securing rivet or screw, and this hole may also be sealed. The rivet or screw may secure a foot in place, or may itself be so formed as to constitute the foot, as will be explained.

[0009] The lid of the case is formed in an exactly similar way, and is similarly sealed to render it weatherproof. The mating surfaces of case and lid are provided with a gasket, and the case is completed by the addition of the hinges, locks and handles, preferably of a recessed type to protect them from damage and allow for compactness in stowage. The case is completed by fitting it with resilient inserts of a material such as plastic foam to receive and protect the contents.

[0010] Figure 3 shows a form of corner member made as a plastic injection moulding, suitable for cases of rather lighter and less expensive construction. The moulding consists of an outer shell 9 formed integrally with a pair of flap-engaging members 10. An external fragmentary view, in which the members 10 are indicated in dotted outline, appears at (b), and (c) is a longitudinal section of a shallower form, to be used for the lid of the case. Assembly of the case is carried out as described above.

[0011] Figure 4 comprises a section and fragmentary views of an alternative corner construction according to the invention.

[0012] In this construction the corner member consists of two separate elements. The outer element, 11, is of metal, of a shape conforming to the outside of the corner, and having an inwardly-­projecting rib 12 of divergent section. The inner element 13 is a sheet metal pressing shaped to conform to the inside of the corner, but with a corresponding recess 14. Each of the elements has a flange 15,16, which will abut against the bottom of the case when assembled, and rivet holes in the flanges permit the elements to be secured to one another after assembly and allow for the attachment of feet.

[0013] The case is formed, as before, by cutting, notching and bending the sheet material, and then, at each corner, the outer element 11 is slid into position from the bottom and the inner element 13 is slid over it from the top, clamping the flaps 4 against the diverging sides of the rib 12. The foot is then attached by means of a rivet which passes through the rivet holes in the flanges 15 and 16, locking the structure together. The lid of the case is similarly formed and secured, and the joints sealed and a gasket provided, as required. The case is completed by the fitting of hinges, locks and a handle, and by the provision of shock-absorbing material in the form of a resilient insert, in the usual manner.

[0014] Figure 5 shows, in axial section, two types of rivet which may be used in combination to fasten the case corners and at the same time provide protective feet for the cases and aid in their stacking. The rivets serve to fasten the corner members in place, and they are provided with considerably enlarged heads. The heads (17) of one type of rivet are conical in form, while those of the other type have a corresponding conical depression (18). The conical-headed rivets are preferably used to fasten the corner members of the lid, while those bearing depressions are used to fasten the corner members of the case body. When the cases are stacked one on top of the other, the depressions in the case body rivets engage the conical heads of the lid rivets to prevent the upper case sliding on the lower one. The reverse arrangement may also be adopted, but that described has the advantage that since the depressions do not face upwards they are less liable to become filled with dirt.

Claims

1. A method of making a lid or body for a case suitable for the transportation or storage of delicate equipment, in which a sheet (1) is cut and bent to form the base and sides of the body together with a flap (4) at each end of each side turned inward at an acute angle, and a member (5) so shaped as to engage the flaps is applied at each corner, characterised in that the corner of the sheet is cut away to enable the corner member to be slid over the flaps from the outside of the lid or body, the corner member includes three mutually perpendicular faces, one flush with each of the faces meeting at the corner, the corner member is so shaped as to completely enclose the corner on all sides, and is secured in position by fastening means passing through the base.

2. A method of making a lid or body according to claim 1 in which the corner member is formed from metal strip.

3. A method of making a lid or body according to claim 1 in which the corner member is formed by one or more plastic injection mouldings.

4. A method of making a lid or body according to any preceding claim in which each corner member comprises an outer element (11) and an inner element (13), the outer element being formed with an inward-facing rib (12) of divergent cross-section against which the flaps abut, and the inner element having a corresponding recess and sliding over the flaps to secure them against the rib.

5. A method of making a lid or body according to claim 4 in which both the inner and outer elements are provided with flanges (15, 16) and are secured in position by a screw or rivet passing through both flanges.

6. A case suitable for the transportation or storage of delicate equipment, comprising a case body and a case lid, each made by the method of any preceding claim, and arranged to be attached to one another.

7. A case according to claim 6 in which each corner member is sealed to the adjacent surface of the lid or body to render it water-resistant, and a sealing gasket is provided between the lid and body.

8. A case according to claim 6 or claim 7 provided with an insert of resilient material.

9. A case according to any of claims 6, 7 or 8 in which the rivets securing the corner members of the case body have enlarged heads (18) to provide feet for the case, and the rivets securing the corner members of the lid are of complementary form (17) so as to engage the body corner member rivets and prevent the cases from sliding when they are stacked on one another.

Drawing