GB2275005A - Method of mass-producing an electrical column radiator - Google Patents

Abstract

The method includes the step of joining adjacent columns of a radiator by slidably engaging cooperating flanges which may be outwardly or inwardly directed and then causing deformation or outward flaring of the flanges to secure adjacent panels (or columns) together. Peripheral edges of the columns are preferably joined by a folding technique e.g. by folding flanges 10a, 10b. The method facilities mass production and avoids the use of welding. Adhesives may be used as an alternative. <IMAGE>

Description

METHOD OF MASS-PRODUCING AN ELECTRICAL COLUMN RADIATOR This invention relates to a method of mass-producing electrical column radiators of the kind which do not contain oil or any other liquid. The method may be used, for example, to manufacture radiators in accordance with the invention disclosed in our co-pending Application entitled "Electrical Column Radiator", although it may also be applied to other column radiators of the "dry" type. One of the primary objects of the invention is to provide a method of manufacturing "dry" radiators without welding.

In particular, it seeks to avoid welding when joining individual sections to form a column array and when joining the two halves of individual column sections.

Oil-filled electrical radiators have enjoyed a very long period of popularity as domestic space heaters. Such radiators may be of either a panel, or a column type. The latter is often preferred, because it simulates the traditional column radiator having heavy cast-iron hollow columns or sections connected to a central heating system for transferring heat by the circulation of hot water. The oil-filled electrical radiator had the appearance of these traditional radiators and the added advantage of portability and ease of use, since it could be simply placed in a room to be heated and connected to an electrical supply.

Moreover, instead of using heavy cast-iron sections, the electrical radiator had columns made from sheet material which could be pressed and welded together to avoid the disadvantages of cast-iron.

Figs. 1-3 schematically illustrate a typical prior art, oil-filled radiator having a plurality of columns 1 each consisting of a pair of confronting walls or panels 2 made from sheet metal. These panels are pressed out so as to define upper and lower bosses 3,4 and a generally ribbed intermediate portion 5. (Inwardly formed recesses 6 cause portions 7 of the walls or panels 2 to touch inside each column, as shown in Fig. 3.) The panels 2 are joined together by spot welds 8 and by peripheral welds 9 extending around the entire outward peripheral edges 10 of each column 1. The columns are then assembled on jigs so that inside peripheral edges 11 of the bosses 3,4 can be welded from inside the radiator. A heating element 12 extends directly through a passageway 13 which is defined by corresponding apertures in the lower bosses 4 of the radiator. This heating element is of the sheathed-wire type in which a central resistance wire is insulated from an outer sheath by a powdered insulating material packed between the wire and sheath. The element 12 is supported in passageway 13 (by means not shown) and sealed into the radiator body.

The technique for manufacturing and assembling the columns of this prior art, oil-filled radiator can be both complex and time-consuming. Although the side panels 2 of each column can be easily mass-produced by pressing techniques, careful welding is required to seal the confronting peripheral edges 10 (to make the peripheral welds 9) in order to form each individual column, as well as to join adjacent bosses 3,4 of each column to build-up the column array. In an oil-filled radiator, such welds must provide hermetic seals in order to prevent oil leakage.

Whilst the peripheral welds 9 can be made from the outside of each column and hence pose less problems with regard to welding, inspection and (where necessary) repair, these are resistance seam welds which are time-consuming to make since they must be made around the entire periphery of each individual column. With regard to joining the inside peripheral edges 11 of the bosses 3,4, these are welded from the inside of the radiator and welding usually involves the insertion of a welding head which must be carefully aligned and then operated to make an hermetic weld. The head is usually inserted along the longitudinal axis of the transverse passageway through the aligned bosses and then positioned at a precise location. The head is then rotated to make the internal peripheral seam weld which joins the bosses 3,4. As these welds are made on the inside of the radiator, they are clearly more difficult to make accurately and they cannot be easily inspected. Moreover, they are also time-consuming because of the way in which individual columns need to be stacked and the welding head inserted before the confronting edges of bosses 3,4 are seam welded.

A further step in the process involves testing the welded column arrays for leaks and this involves plugging open apertured bosses of the end columns, connecting an air supply to the radiator to pressurize its interior and immersing the radiator in water to detect leaks by escaping air bubbles. This clearly adds to the complexity and time required for mass production.

Attempts have been made in the past to provide a "dry" alternative to the traditional column radiator, but these have not resulted in arrangements which are suitable for mass production. A dry electrical column radiator is disclosed in GB-A-373 252, but this employs a plurality of wrought iron or cast-iron columns which are secured together by welding and by tie-rods. Another column radiator is disclosed in DE-A-918 219 which has columns made from pressed steel metal plates which can be secured together in various ways. This reference specifically teaches a method of securing the columns together at the top of the radiator by means of a tube, acting as a tie-rod, which passes through corresponding apertures in the columns, the columns being separated by spacing collars. At the bottom of the radiator, the columns and spacers are riveted, screwed or welded to a base structure. Whilst this arrangement dispenses with some welding between columns, the construction of the radiator is not entirely suitable for mass production. Moreover, no special techniques are disclosed in DE-A-918 219 to facilitate mass-production.

A more recent attempt to produce dry column radiators is disclosed in EP-A-0251973. This reference mentions the disadvantages of oil-filled radiators with regard to the costs incurred through using special, non-corrosive and nontoxic thermal oil; a long complex welding operation which is necessary to provide fluid-tight seals around the peripheral edges of the confronting panels of individual columns; and the requirement, in oil-filled radiators, for a heating element of sufficient quality to withstand the corrosive action of oil which decomposes with time.

However, as far as this reference is relevant to this Application, it appears to teach only a welding technique for joining confronting panels of individual columns and for joining corresponding flanges of adjacent columns. This welding would lead either to the kind of problems noted above with regard to oil-filled radiators (although these welds need not be hermetic), or to the following problem, if spot-welding is used.

If the peripheral edges of the side panels of a column are spot welded together, spaces will be left between the spot welds, because the panels are not joined continuously around the entire peripheral edges of each column. These spaces will vary, due to manufacturing tolerances, and the panels will, in use, be subject to differential expansion forces. These differential expansion forces are due to thermal cycling of the radiator, over extended periods, and can cause unsightly gaps to open between sections of the peripheral edges. Any attempts to avoid spot welding also need to avoid this problem, besides providing a secure joint between each of the columns so that the overall rigidity of the column array is preserved. Loose joints would be useless, since they would not preserve this rigidity, and may be a safety hazard if the sections of the radiator became loose and ultimately detached.

The present invention seeks to overcome these problems and to facilitate mass production of dry column radiators, at least with regard to joining individual columns together.

In the preferred embodiment of the invention, welding can be entirely eliminated so that the dry column radiators can be mass-produced at far less cost and without the additional energy requirements or air pollution of welding techniques.

In accordance with the invention, a method of producing an electrical dry column radiator comprises the steps of: making panels which form pairs of confronting walls for each column of the radiator, said walls having corresponding flanged apertures and peripheral edges; and joining peripheral edges of said walls and joining the flanged apertures of adjacent panels to form a column array; characterised by making the panels so that the flanged apertures of adjacent panels are directed outwardly and inwardly; introducing the outwardly directed flanges into the inwardly directed flanges; and causing deformation, expansion or adhesion between the flanges whereby the columns are secured together without welding.

In a preferred embodiment of the invention, each panel has at least upper and lower flanges which are either outwardly directed or inwardly directed. These flanges may be formed by pressing when the panels are made. (It would also be possible to have both outwardly and inwardly directed flanges in the same panel, if the corresponding flanges in the other panel were oppositely directed.) Preferably, these flanges are of circular form (although other shapes are possible) and are dimensioned so that the outwardly directed flanges of one column can be slidingly or telescopically engaged with the inwardly directed flanges of an adjacent column. Thus, the walls of each column have a generally similar construction, but they are not identical with regard to the dimensions of the flanges. After the flanges between adjacent columns have been slidingly or telescopically engaged, a suitable tool can then be introduced which is adapted to deform or expand the periphery of at least one flange so as to result in a secure joint.

In a preferred embodiment, the panels have cylindrical flanges, one with a smaller diameter than the other. The smaller diameter flange may project more than the larger diameter flange or both may project equally from the plane of respective bosses in the panels. The flanges can be outwardly deformed or flared to form a secure joint. This may be achieved by using a suitable tool, such as a mandrel with a radially movable member, the mandrel being inserted through the flanges when engaged so that the member can then be moved radially into a position where it is then rotated so as to flare the peripheral edges of the flanges.

Alternatively, the tool may be a mandrel held in a stationary position (after insertion) and having members which expand radially so as to cause the required deformation to form a secure joint. The deformation or expansion does not need to be made entirely circumferentially, since deformations could be made at spaced points around the circumference of one flange or both flanges to achieve the same effect. Any suitable tool may be used to cause sufficient deformation or expansion to ensure a secure joint.

In a preferred embodiment, the confronting walls of each column of the radiator have flanges which extend in the same direction. For example, the outwardly directed flanges in one wall project in the same direction as the inwardly directed flanges of an adjacent or opposite wall. (In the preferred embodiment, each column has upper and lower flanges which project from respective bosses formed in the panels.) When the flanges project in the same direction, tools can be inserted from one side of the array to cause the required expansion, or deformation. For example, a double-headed machine would have upper and lower tools for simultaneous insertion into the engaged flanges of stacked columns. However, the column array may be built up in various ways, for example, by joining individual panels; pre-joining panels to form columns and then joining the columns; or first joining panels to form groups or sets of joined columns (e.g. twos threes, etc.), which are then assembled, in modular fashion, to form an array of the required size. The technique used will optimise the steps required for automatically picking-up panels/columns; for placing them one on the other; for inserting, operating and withdrawing expansion or deformation tools; and otherwise assembling the array. Although the panels could all be pre-stacked and then secured simultaneously, or individual panels or columns could be joined one at a time, the panels or columns would best be joined in modular groups or sets to take account of the choice of tools used and optimisation of the time taken to produce an array.

Preferably, the peripheral edges of the flanges are flared outwardly when joined. However, the flared edges may be further crimped, pressed or curled for greater security.

It may also be possible to use heat resistant resin adhesives so as to bond the flanges together, such adhesives being of the kind which are heat-cured to form a reliable and resilient bond. Where adhesives are used, this needs to withstand the temperature of the radiator and also have sufficient flexibility to accommodate differential expansion between the panels. Such an adhesive forms a resilient bond hence reducing problems due to differential expansion.

The peripheral edges of the walls of each column are preferably secured together by techniques which do not employ welding. For example, the peripheral edge portion of one panel, in each of a pair of panels, may be folded over the peripheral edge portion of the other panel so as to provide an attachment thereto without welding.

Alternatively, the peripheral edge portions can be secured together by means of an adhesive.

The method of the invention can be applied particularly, but not exclusively, to the radiator described in our copending Application entitled "Electrical Column Radiator".

This radiator has the added advantage, over the radiators disclosed in GB-A-373 252, DE-A-918219 and EP-A-0251973, that it employs a more conventional heating element or elements which extend straight through the passageway defined by corresponding apertures that extend transversely through the column array. The prior art radiators employ various forms of heating element which are of comparatively much longer length and hence more expensive, and which must also be configured to extend into each of the columns to distribute heat evenly through the columns of the radiator.

Besides being more expensive, these heating elements create problems of assembly and are more time-consuming to install hence making them unsuitable for the mass-production of dry column radiators.

When the method of the invention is applied to a radiator having a straight element or elements, the method preferably includes the step of introducing the heating element or elements through the passageway which extends transversely through the column array. This is a simple process which saves much time in mass-production, besides employing heating elements of shorter and more conventional design.

Embodiments of the invention will now be described with reference to some of the accompanying schematic drawings, in which: Figs. 1-3 illustrate an oil-filled radiator of known construction, Figs. 4-7 respectively show front and side elevations of a column, a plan view, in section, of the top of a column, and a radiator in which the columns are used to make radiators in accordance with the method of the invention, Figs. 8 and 9 illustrate stages in different techniques for joining adjacent columns to form a column array in accordance with the method of the invention, Fig. 10 illustrates how groups of columns are joined to each other, by means of an expansion tool, Figs. 11 and 12 show different expansion or forming tools, Figs. 13-16 illustrate various techniques for joining peripheral edges of the side panels of the radiator without welding, and Figs. 17 and 18 are sectional views of a bottom portion of a radiator showing a method of attaching a foot assembly.

Referring to Figs. 4-7, a dry column radiator made according to the preferred embodiment of the invention includes a plurality of columns 1, each made from two pressed steel panels 2a,2b having the same general appearance. Panels 2a,2b are joined together at their peripheral edges, preferably by folding and pressing, to form folded joints 10. Each panel 2a,2b is also pressed out to define an upper boss 3 and a lower boss 4, in which respective apertures 15,16 are provided. Fig. 6 shows apertures 15 in the upper bosses 3 of confronting panels 2a,2b. These apertures are defined by either out-turned or in-turned flanges 17,18 which are designed so that one fits within the other (see Figs. 8 and 9) whereby adjacent columns can be secured together, by means of the technique described in more detail below, to form -an array of substantially vertical and parallel columns of the required width. Fig. 7 shows such a column array and the bottom the radiator body is broken away to show a heating element 12 passing directly through the aperture of the aligned lower flanges of bosses 4. The apertures in the lower bosses define a transverse passageway extending through the column array in which a heating element, or heating elements are supported. The element or elements 12 extend straight through this passageway, i.e. without passing upwardly inside the columns and are fitted to insulating end plates which close the apertured bosses 4 of the end columns.

However, other means of support may be used.

A preferred construction of these columns, to ensure uniform heat distribution in the radiator, is described in more detail in our co-pending Application entitled "Electrical Column Radiator". The present Application deals mainly with a method of making and assembling (a) panels which are formed into columns that are used to build a radiator. Hence, the drawings of the columns do not include the same kind of detail as that shown in the copending Application.

The preferred method of securing together adjacent columns of the radiator will now be described in more detail with reference to Figs. 8-12. It will be first assumed that the peripheral edges of the panels have already been joined together to form individual columns.

Figs. 8 and 9 each show a vertical section through the bosses (3 or 4) of adjacent panels of the columns to be fixed in the vertical array. Only portions of the confronting panels 2b,2a, of an adjacent pair of columns are shown. Panel 2b has an inwardly directed flange 18, of cylindrical form (although other shapes are possible).

Panel 2a has an outwardly directed flange portion 17 of generally cylindrical form (but this could be of another shape to suit flange 18.) Fig. 8A shows the adjacent panels slightly spaced apart and prior to inserting the outwardly directed flange 17 into the inwardly directed flange 18.

Fig. 8B shows initial sliding or telescopic engagement between the flanges, whereby adjacent bosses abut one another. It will also be seen that the inner flange projects further than the outer flange. Although the columns are shown in their vertical orientation, they would normally be stacked horizontally whereby columns can be placed one on top of the other and gravity assists placement of the other column on a lower column, whilst the flanges provide convenient locations.

Fig. 8C shows a subsequent stage in which both flanges 17 and 18 have been expanded in an outwardly radial direction, i.e. so as to flare outwardly. This flare is designated 43 in Fig. 8C. This expansion provides a secure and firm location and prevents play between the joined columns whilst preventing detachment of one column from another. It will appreciated that the security of this assembly is assisted by making similar joints in upper and lower bosses 3,4. If the radiator was particularly tall, more bosses could be provided along the axial direction of the columns, with similar joints. Alternatively, if the radiator had very short columns, it may be possible to have only one row of bosses which are joined in the manner described with reference to Fig. 8 (or 9). However, in this case, if the flanges were circular, it would be preferable to include additional means to prevent any relative rotation between adjacent columns. Otherwise, non-circular flanges would be suitable.

Figs. 9A-9C show an alternative technique. After initial engagement (Fig. 9A), where the inner flange 17a projects more than the outer flange 18a from the respective panel wall, the flanges are flared (Fig. 9B) and then subsequently flattened (Fig. 9C).

Fig. 10 schematically illustrates how groups or sets of columns may be joined in e.g. threes, twos, or singly, to build up an array. Fig. 10 shows the upper head of a double-headed machine, each head having an expanding mandrel 45 with two forming sections 46 which can be used to deform opposite pairs of flanges. The expanding mandrel 45 is inserted so that the forming sections 46 align with the engaged flanges of columns la,lb and lb,lc. A tapered rod 47 is pushed into the mandrel so that it expands and causes the forming sections 46 to flare the corresponding flanges.

In this embodiment, the flanges all extend in the same direction so that the mandrels can be inserted from one side. Whilst this technique enables a group of three columns to be simultaneously joined, it will be clear that the columns can be joined in groups of other than three.

Radiators having different thermal outputs can thereby be constructed, in a modular fashion, by assembling the required number of group-connected columns. If the columns are joined in groups or sets, a shorter mandrel can be used than in the case where individual columns are stacked into an array and a (long) mandrel would need to be inserted and then operated for joining individual columns.

Figs. 11a and 11b are end-on axial views of a tool having a cylindrical form, with segmented portions 20 surrounding a central hole 21 which accommodates a suitably shaped expansion rod (not shown). In Fig. lla, the expansion rod has been withdrawn from the central hole so that the segmented portions touch one another and thereby occupy the least volume. Fig. 11b shows a stage at which the expansion rod has been pushed through the central hole 21 so as to cause the segmented portions 20 to expand radially outwardly, thereby creating gaps 22 between these portions as shown in the Drawing. The segmented portions then occupy a greater volume to cause the outward flaring of the telescopically engaged flanges (as described above).

Fig. 11c is a side view of the end portion of the tool showing the form of the segmented portions when the expansion rod (not shown) is pushed through hole 20.

Fig. 12 shows an alternative tool in the form of an eccentric rotating former 23,24. In Fig. 12a, the former has a mandrel portion 24 with a wedge-shaped forming portion 23 at one end. The mandrel portion is inserted through the telescopically engaged flanges 17,18 along a path which is off-set from the central axis 25 of the flanges (it is thereby eccentrically located with regard to subsequent rotation). The mandrel portion is drawn so as to force the wedge-shaped former 23 against the edges of the flanges 17,18 and the mandrel portion is then caused to rotate on a circular path 26 about the central axis through the telescopically engaged flanges. This is illustrated schematically by Fig. 12b, whereby the former turns up the flanges, as it rotates, to achieve the purpose of joining adjacent columns.

Preferably, the panels of each column are joined together by a weldless technique before the columns are joined to one another as explained above.

The order of assembly of the panels and the columns may be varied without departing from the broad concept of the invention. However, in general terms, it is preferred that welding is totally eliminated from the assembly processes.

Techniques for joining the panels, without welding, to form columns will now be described.

The peripheral rim portions 10 of confronting panels 2a,2b may be secured by folding. Figs. 13-16 illustrate different methods of folding the rim portion of one panel over the rim portion of the other panel to secure the panels together without welding. These Drawings are schematic in that gaps between the rim portions have been exaggerated for clarity, since one panel would fit tightly against another in practice and there would also be no gaps between the folded edges since these would be pressed together in tight abutment.

In Figs. 13a-13c, the peripheral rim portions 10a,10b of confronting panels 2a,2b are of equal radial extent and are first butted together before a first fold, or a first part of a folding step bends the peripheral edges into a right angle as shown in Fig. 13b. A subsequent fold, or part of a folding step clenches together with peripheral edges as shown in Fig. 13c.

In Figs. 14a-14c, rim portion 37c has greater peripheral extent than rim portion 37b (as seen in Fig. 14a). Fig. 14a shows a first fold of rim portion 37c and Fig. 14b shows a second fold of the same rim portion which provides a rounded finish concealing the cut edges of the panels.

In Fig. 15, rim portion 37c also initially extends more than rim portion 37b but, after being folded around the edge of rim portion 37b, the folded edge is tucked under itself as shown in Fig. 15b. In this case, the rim portions 37b, 37c extend further than in the case of Figs. 14a-14c.

In Fig. 16a, panel 2b is formed with a peripheral recess 37d. The upstanding rim portions 37b, 37c are initially staggered, as shown in Fig. 16a, whereby a first fold is made (Fig. 16b), and then a second fold (Fig. 16c), before the folded edges are tucked round into the recess 37d (Fig.

16d). The resulting roll of folds 37e provides a neater and almost flush finish, except for small gaps between the panels 2a,2b. This gap would be insignificant and/or may be concealed by a suitable finishing process.

Generally speaking, the folding technique is employed so as to provide a secure attachment between the rim portions of the panels around the entire periphery of the column member and also to conceal cut edges. Preferably, a plurality of folds are made to improve the security of the join and also to conceal edges as far as possible. In certain of these embodiments, the rim portions are curled together to form generally spiral folds.

Instead of using the folding techniques described above, or in addition thereto, adhesives may be employed to achieve the same purpose.

Referring to Figs. 17 and 18, these illustrate a method of attaching one of two feet to the bottom of a radiator.

The radiator may be made in accordance with the method of this invention, or it may alternatively be a radiator made by a different method but having columns with bottom portions with a shape adapted to cooperate with the foot assembly now described.

Each foot assembly comprises a foot moulding 40 having a downwardly protecting portion 41 which is shaped to give a stable support to the radiator body, which includes columns le,lf. Portion 41 also defines a lower chamber 42 into which an axial portion 43 depends. Portion 43 has an axial through hole 44, which provides clearance for a threaded bolt 45 having a wing head 46 to enable the bolt to be tightened. An upper integral portion 47 of moulding 40 defines a generally annular cup with a flexible cylindrical wall. Bolt 45 is threadably connected to a nut 48 which has a T-shaped cross-section. Nut 48 is received in a tapered plug 49 so that when the bolt 45 is tightened, the nut 48 will be drawn downwardly, thereby pulling the tapered plug 49 into the mouth of the annular cup 47.

Fig. 18 shows bolt 45 fully tightened, whereby the tapered plug 49 has been forced into cup 47, causing its annular walls to be deformed outwardly or flared, as shown in the drawing. This flaring causes the cup 47 to grip the sides of columns le,lf. In this case, the bottom of each column terminates in a bulbous shape, whereby the outwardly flared rim of the cup 47 can be securely located.

If the foot assembly is used with a different radiator, the bottom portions of the columns preferably terminate in shapes which enable the outwardly flared rim of cup 47 to be securely located, as explained above. However, other arrangements may be possible wherein outward deformation of a member causes the foot assembly to be secured.

An advantage of this technique is that the foot assembly can be readily secured to a radiator body in any required position, i.e. between columns. This facilities assembly, without welding, of radiators having different lengths and/or changing the position of feet along the length of the radiator body. Also, two or more feet could be attached as may be required.

Claims (10)

CLAIMS:

1. A method of producing an electrical dry column radiator comprises the steps of: making panels which form pairs of confronting walls for each column of the radiator, said walls having corresponding flanged apertures and peripheral edges; and joining peripheral edges of said walls and joining the flanged apertures of adjacent panels to form a column array; characterised by making the panels so that the flanged apertures of adjacent panels are directed outwardly and inwardly; introducing the outwardly directed flanges into the inwardly directed flanges; and causing deformation, expansion or adhesion between the flanges whereby the columns are secured together without welding.

2. A method according to Claim 1, wherein each panel has at least upper and lower tubular flanges which are slidingly or telescopically engaged prior to causing said deformation, expansion or adhesion.

3. A method according to Claim 1 or 2 wherein the flanges are deformed or expanded together by flaring both flanges outwardly.

4. A method according to Claim 1, wherein the flanges are joined by adhesion and including the step of applying a heat resistant, resilient adhesive between confronting contacting surfaces of the flanges before the columns are joined.

5. A method according to any of the preceding Claims wherein the peripheral edges of the walls of each column are joined together by a folding technique which does not employ welding.

6. A method according to any of the preceding Claims wherein the peripheral edges of said confronting walls are first joined to form individual columns before the flanges are joined to form the column array.

7. A method according to any of the preceding Claims including the step of introducing a heating element or elements through a passageway extending transversely through the column array, said passageway being defined by aligned flanged apertures of the columns.

8. A method according to any of the preceding Claims wherein the columns are joined together in groups before the groups are joined together to form the column array, the number of columns in each group being either similar or different to enable arrays of different sizes to be constructed in a modular fashion.

9. A method according to Claim 8 wherein the flanges all extend in the same direction and a tool or tools, for causing said expansion or deformation, are introduced from one side of the column stack.

10. A method of mass-producing electrical dry column radiators substantially as herein described with reference to Figs. 11-13 of the accompanying Drawings.