GB2167323A - Manufacture of a safety cage for an electric fan - Google Patents

Abstract

A safety cage for an electric fan comprises an annulus of expanded metal with the dimensions of the mesh openings 1 becoming progressively larger nearer the outer periphery. The cage is made by making a plurality of linear discontinuous cuts in metal plate 4 extending from side 4' to side 4'', the cuts becoming progressively larger the nearer side 4'', and then pulling the other opposed sides of the plate 4 away from each other so that the cuts are opened and the plate becomes an annulus. <IMAGE>

Description

SPECIFICATION Safety cage for an electric fan This invention concerns a safety cage for an electric fan.

One type of safety cage is made by spotwelding lengths of wire criss-crossing one another and then coating them with nickel.

Another type of safety cage is made of plastics.

According to the invention a method of making a safety cage for an electric fan comprises providing a rectangular plate of metal, cutting through the plate to form a plurality of linear discontinuous cuts extending in the direction from one side of the rectangle to the other, the cuts becoming progressively longer the nearer tie other side, and then pulling the other opposed sides of the rectangular plate away from each other such that the cuts are opened and the plate becomes an annulus.

In another aspect the invention provides an expanded metal annulus, in which the dimensions of the mesh openings get progressively larger the nearer the outer periphery.

Embodiments of the invention will now be described by way of example, reference being made to the accompanying drawings, of which: Figure 1 is a front view of a safety cage for an electric fan made according to the invention; and Figures 2, 3 and 4 show intermediate stages in the manufacture of cages according to the invention having different mesh shapes.

The safety cage shown in Figure 1 has an expanded metal annulus with diamond shaped mesh openings 1, with cut edges 2 and joins 3. The cage has an inner frame 5 and an outer frame 6 to which the expanded metal annulus is fixed.

In Figures 2, 3 and 4 a rectangular plate 4 has opposed sides 4' and 4", side 4' forming the inner periphery and the side 4" the outer periphery of the annulus.

The mesh or expanded metal can be formed with a quadrilateral diamond shape as shown in Figures 1 and 2 and can be formed with a hexalateral diamond shape as shown in Figure 3 and, further, can be formed with an elliptical shape as shown in Figure 4. Furthermore, the mesh can be formed to any desired shape by processing formation of the cut 2 and the join 3 by means of fitting the shape of the cutter for cutting to the purpose of forming a mesh to the curving state.

In examples, 0.5 to 0.5 mm thick metal plate 4 is prepared 200 mm X 180 mm in size and cutting at intervals of 1.1 mm is carried out by 88 through 91 lines to form a mesh-in order to form a 360O annulus. And in case of cutting by 91 lines, the first cut part and last cut part become the connecting part.

A 0.5 to 0.8 mm initial metal plate becomes 1.1. mm in thickness when the work of cutting for forming the mesh and forming the annulus is finished, and then all sharp parts can be smoothed by conventional methods.

The 200 mm width of the metal cage is chosen to fit to the dimensions of the electric fan, namely, the processing is carried out according to the dimensions of the electric fan.

Argon welding is done to the cut part of the 91st line and then spot welding is carried out for connecting such an annulus with the same quality of inner frame 5 And outer frame 6.

The annulus made of 200 mm X 180 mm metal plate is 500 mm in diameter but the diameter becomes 415 mm in accordance with the shape of the electric fan, namely, the shape of the curve of the front side of electric fan.

As the cage of the invention is made of 1.1 mm thick expanded metal, it is stronger than the conventional cages, further, does not become rusty after long term use if made of, for example, stainless steel, and does not change its colour. The appearance of the cage of the invention is attractive. Furthermore a cage according to the invention can be produced with little material.

1. A method of making a safety cage for an electric fan comprising providing a rectangular plate of metal, cutting through the plate to form a plurality of linear discontinuous cuts extending in the direction from one side of the rectangle to the other, the cuts becoming progressively longer the nearer the other side, and then pulling the other opposed sides of the rectangular plate away from each other so that the cuts are opened and the plate becomes an annulus.

2. A method of making a safety cage for an electric fan substantially as herein described with reference to and as shown in the accompanying drawings.

3. A safety cage for an electric fan when made by a method as claimed in Claim 1 or 2.

4. An expanded metal annulus in which the dimensions of the mesh openings get progressively larger nearer the outer periphery.

5. An expanded metal annulus substantially as herein described with reference to and as shown in the accompanying drawings.

6. A cage for an electric fan in which the meshes are formed as outwardly enlarged shape in round direction in the metal plate leaving the cut parts and the joins so as to form said cage integrally by cutting.

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

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Safety cage for an electric fan This invention concerns a safety cage for an electric fan. One type of safety cage is made by spotwelding lengths of wire criss-crossing one another and then coating them with nickel. Another type of safety cage is made of plastics. According to the invention a method of making a safety cage for an electric fan comprises providing a rectangular plate of metal, cutting through the plate to form a plurality of linear discontinuous cuts extending in the direction from one side of the rectangle to the other, the cuts becoming progressively longer the nearer tie other side, and then pulling the other opposed sides of the rectangular plate away from each other such that the cuts are opened and the plate becomes an annulus. In another aspect the invention provides an expanded metal annulus, in which the dimensions of the mesh openings get progressively larger the nearer the outer periphery. Embodiments of the invention will now be described by way of example, reference being made to the accompanying drawings, of which: Figure 1 is a front view of a safety cage for an electric fan made according to the invention; and Figures 2, 3 and 4 show intermediate stages in the manufacture of cages according to the invention having different mesh shapes. The safety cage shown in Figure 1 has an expanded metal annulus with diamond shaped mesh openings 1, with cut edges 2 and joins 3. The cage has an inner frame 5 and an outer frame 6 to which the expanded metal annulus is fixed. In Figures 2, 3 and 4 a rectangular plate 4 has opposed sides 4' and 4", side 4' forming the inner periphery and the side 4" the outer periphery of the annulus. The mesh or expanded metal can be formed with a quadrilateral diamond shape as shown in Figures 1 and 2 and can be formed with a hexalateral diamond shape as shown in Figure 3 and, further, can be formed with an elliptical shape as shown in Figure 4. Furthermore, the mesh can be formed to any desired shape by processing formation of the cut 2 and the join 3 by means of fitting the shape of the cutter for cutting to the purpose of forming a mesh to the curving state. In examples, 0.5 to 0.5 mm thick metal plate 4 is prepared 200 mm X 180 mm in size and cutting at intervals of 1.1 mm is carried out by 88 through 91 lines to form a mesh-in order to form a 360O annulus. And in case of cutting by 91 lines, the first cut part and last cut part become the connecting part. A 0.5 to 0.8 mm initial metal plate becomes 1.1. mm in thickness when the work of cutting for forming the mesh and forming the annulus is finished, and then all sharp parts can be smoothed by conventional methods. The 200 mm width of the metal cage is chosen to fit to the dimensions of the electric fan, namely, the processing is carried out according to the dimensions of the electric fan. Argon welding is done to the cut part of the 91st line and then spot welding is carried out for connecting such an annulus with the same quality of inner frame 5 And outer frame 6. The annulus made of 200 mm X 180 mm metal plate is 500 mm in diameter but the diameter becomes 415 mm in accordance with the shape of the electric fan, namely, the shape of the curve of the front side of electric fan. As the cage of the invention is made of 1.1 mm thick expanded metal, it is stronger than the conventional cages, further, does not become rusty after long term use if made of, for example, stainless steel, and does not change its colour. The appearance of the cage of the invention is attractive. Furthermore a cage according to the invention can be produced with little material. CLAIMS

1. A method of making a safety cage for an electric fan comprising providing a rectangular plate of metal, cutting through the plate to form a plurality of linear discontinuous cuts extending in the direction from one side of the rectangle to the other, the cuts becoming progressively longer the nearer the other side, and then pulling the other opposed sides of the rectangular plate away from each other so that the cuts are opened and the plate becomes an annulus.

2. A method of making a safety cage for an electric fan substantially as herein described with reference to and as shown in the accompanying drawings.

3. A safety cage for an electric fan when made by a method as claimed in Claim 1 or 2.

4. An expanded metal annulus in which the dimensions of the mesh openings get progressively larger nearer the outer periphery.

5. An expanded metal annulus substantially as herein described with reference to and as shown in the accompanying drawings.

6. A cage for an electric fan in which the meshes are formed as outwardly enlarged shape in round direction in the metal plate leaving the cut parts and the joins so as to form said cage integrally by cutting.