EP1918669B1

EP1918669B1 - A method for producing head element for heaters and the element obtained by the method

Info

Publication number: EP1918669B1
Application number: EP20060123275
Authority: EP
Inventors: Valter Lolli
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-10-31
Filing date: 2006-10-31
Publication date: 2009-05-06
Anticipated expiration: 2026-10-31
Also published as: EP1918669A1

Description

The present invention relates to the production of heaters, in particular, to the production of head elements used for supporting and connecting the tubular heating elements, which form the heater.
In the following description, reference will be made to patent EP 1395785 , concerning the same head element and the method to obtain it.
Heaters are mostly produced by joining tubular elements and head elements. The groups, composed of two or more tubular elements joined by two heads, are connected to each other by liquid-tight connection forming a heater.
There are different methods for producing the head elements, such as those described by the Patent Publications FR 1.201.614 and CH 372.448 .
Typically, the head element includes a hollow body with tubular extensions situated on a narrow side and two opposite apertures made on two wider surfaces.
To manufacture the heater, two head elements are each time welded to opposite ends of some tubular elements (usually three); then more groups formed by the heads and tubular elements are joined at the apertures, by welding or screwing after threading.
The publication EP-A-0854347 describes a method for obtaining head elements, which have an aperture on their narrow side, opposite to the side with the tubular extensions for connection with the tubular elements.
The aperture allows easy insertion and support of a shaped core into the die during the fusion, and subsequent cleaning and finishing of the inner cavity. However, it is necessary to close the aperture before assembling the tubular elements.
According to a conventional method, the head elements are obtained by welding two semi-shells of sheet metal along their contour.
The welding of the two semi-shells is very difficult, because of critical positions, as it extends along the matching line of the two curved surfaces. Moreover, the head element must be liquid-tight, so the welding must be performed very carefully, thus increasing the difficulty, time and costs of this working operation.
Not to say that, after the welding had been finished, it is necessary to finishing the whole welded area, in order to make it shapely, this step increasing the production time and costs.
A problem generally encountered while producing these head elements, is the presence of regions which are critical for welding, e.g. between the holes for the tubular elements.
The object of the present invention is to propose a method for producing a head element composed of one single body, by pressing steps, without the drawbacks resulting from the fusion procedure and with a shapely product being obtained.
Another object of the present invention is to propose a method, which allows a reduction of time and costs of the head element production.
A still further object of the present invention is to propose a head element obtained by the above mentioned method, whose production is cheap and does not require extensive time, and which avoids positions critical for welding.
A further object of the invention is to propose improvements to the method and the head element disclosed in the patent EP 1395785 .
The above-mentioned objects are obtained by a method and a head element for radiators as recited in independent claims 1, 10, respectively. Further embodiments and advantageous configurations are reported in the sub-claims.
In the following, the invention is described in a more detailed way with reference to particular, but not only embodiments and with reference to the enclosed drawings, in which:

Figure 1 is a lateral section view of the body of a head element during its forming by pressing, according to the present method;
Figures 2, 3 and 4 are a top view, a lateral view and a perspective view, respectively of the body of Figure 1;
Figure 5 is a view of the body of Figure 1 in a subsequent work step;
Figure 6 is a section view of the body along the line VI-VI of Figure 5;
Figure 7 is a view of the body of Figure 5 in another work step of the present method;
Figure 8 is the body of Figure 7 along the line VIII-VIII;
Figure 9 is a section view of the finished head element;
Figure 10 is a view of constructive variant of the body forming the head element;
Figures from 11 to 13 show three work steps necessary to complete the head element according to the above mentioned constructive variant;
Figure 14 is a view of the finished head element, according to the above mentioned constructive variant;
Figure 15 is a view of two finished head elements, according to the above-mentioned constructive variant; joined to each other;
Figure 16, 17 and 18 show a bottom view, a side-sectional view and a different side view of the body obtained in accordance with the improvements, claimed in the following;
Figure 19 shows the head element according to the improvement, in an intermediate step;
Figure 20 shows a detail of the head element of Figure 19;
Figures 21 and 22 show the press-shaping steps of the head element according to this improvement;
Figure 23 show the head element according to this improvement, as finished;
Figure 24 shows a detail of the finished head element;
Figures 25 and 26 concern a different embodiment of the head element according to this improvement.

According to the present method, with reference to the patent EP 1395785 and to Figures from 1 to 4, head elements for heaters are produced beginning from a single piece of sheet metal 1.
The piece of sheet metal 1 is first deep-drawn to obtain a hollow molded piece 2 defined by a base wall 3, two opposite larger sides 4, 5 joined to the base wall 3, two narrower sides 14, 15, joined to the base wall 3 and integral with the two opposite large sides 4, 5, and an open side 6, situated opposite with respect to the base wall 2. Deep drawing operation of the sheet metal 1 is performed by a series of subsequent steps, e.g. three steps.
The intermediate forms assumed by the hollow molded piece 2 during the drawing step are indicated with dotted line and broken ling in Figure 1.
The deep-drawing step can be performed by using a mechanical press or a fluid-pressing device (hydro-forming), or any other suitable apparatus.
Later, the opposite large sided 4, 5 and the narrow sides 14, 15 are cut near the open side 6, along the broken line T of Figure 3, so as to define a hollow body 8 (Figure 4), with an edge 9 uniform and oblong, extending around the open side 6.
A lateral through aperture 12, e.g. circular, is made on each of the opposite large sides 4, 5 (Figure 5).
The aperture 12 can be made by punching or drilling, the choice of the technique depending on the materials used and thickness obtained.
As shown in Figure 9, fastening means 25 are made on each lateral through aperture 12, to allow mutual fastening of the adjacent hollow bodies to assemble groups formed by the head elements and the tubular elements, thus building a heater.
The fastening means 25 can be obtained either by welding a threaded ring 26 around the lateral through aperture 12, or, as shown in Figures from 11 to 15, by making a circular crown 27, extending around each lateral through aperture 12, by applying a pressure directed outwards.
Connection is then made by a threaded joint, in the first case, or by welding the resulting protruding edge 31, in the second case, both the techniques being well known in the art.
The protruding edge 31 is obtained by introducing a flat core 28 into the hollow body 8 through the open side 6, before the tubular extensions 13 are made (Figure 11).
The flat core 28 has a floating element 29, matching each lateral through aperture 12 and pushed outwards alternately in opposite directions.
A die 30, situated on the outer part of the hollow body 8, helps the floating element while pressing (Figures 12 and 13). The protruding edge can be obtained by using a mechanical press or a fluid-pressing device (hydro-forming).
At this point the apertures 12 can be finished, e.g. by boring or other suitable known technique. A threaded ring 38 can be inserted into the seat defined by the protruding edge 31 to complete the fastening means 25, as it fulfills the same function as the ring 26. Otherwise, the adjacent head elements can be joined by welding spots 37 of the circular crowns touching each other, as shown in Figure 15.
Notches 16, suitably spaced apart, are made on each of said opposite large sides 4, 5.
Cylindrical cores 18 are introduced into the edge 9, in the region of areas 19 clear of the notches (Figure 7).
The edge 17, extending around each notch 16 and situated between the two cylindrical cores 18, is pressed to close the sheet metal around the cores and at the same time the notches 16 are widened.
Therefore, the sheet metal in the area of the notches is pushed against the cores 18 and deformed plastically, thus assuming the curved shape of the cores, as well seen in Figure 8.
Afterwards, the cores 18 are withdrawn and the edge 9 is welded along the edge 17 of the widened notches 16.
The tubular extensions 13 are then connected to tubular elements 23 by a small cylinder 24, introduced into each tubular extension 13 and featuring a groove along its circumference, into which a ring 34 of fusible material is inserted.
Then, the end of each tubular element 23 to be coupled is fitted onto the part of the small cylinder 24 protruding from the relative tubular extension 13.
The connection area between the tubular elements 23 and the head element at the corresponding tubular extensions 13 and the ring 34 of the fusible material, is heated by a flame carried rotating around the connection area. Otherwise, the heads and the tubular elements connected thereto, are placed for a suitable time in a heat treatment oven. The heat causes the fusion of the ring 34, thus welding the head elements to the tubular elements 23.
Other welding techniques can be used instead, where more convenient.
Also the hollow body 48 (Figure 18) is obtained from one piece of sheet metal by deep-drawing.
According to the improvements claimed hereinafter, before making the notches, the hollow body is first press-shaped around the cores 18. The result can be seen from bottom in Figure 16, This operation is obviously performed after making the protruding edges 31 and the circular crowns 27.
Then, the notches are made on the depressed area 49, by using suitable known techniques and tools. The overturned "V" shape of the notches, indicated with 46 according to the improvement, is such that the width W of each notch decreases from the bottom of the hollow body inwards.
The length of the notches, and in fact also the width W, depends on many factors, such as the number and diameter of the tubular extensions to make, their reciprocal distance, the thickness of the material. Also the radius R of the inner part of the notches depends basically on the diameter of the tubular extensions, i.e. of the cores 18, and their reciprocal distance.
Basically, the notch appears as shown in Figure 20, which reproduces a relevant detail of Figure 20. The different width of the notch is due to the fact that the material can be stretched less and less going inwards.
As seen in Figure 21, the upper edges 47 are first press-shaped by a upper mould 42 going downwards, in direction D, so that they take the round shape of the cores 18. Then the lower edges 47 are press-shaped by a lower mould 44 going upwards, in direction U, also giving the lower edges the round shape of the cores 18.
The motion of the moulds 42, 44 is not critical, i.e. it could also be horizontal while the hollow body is held vertical.
The moulds 42, 44 have each one a rounded extension 43, 45 mating with the round shape of the cores. Also the part of each extension matching with the radius R of the relevant notch, is rounded, although it has not an abutment part to mate with. The curved section along the inner portion of the notch is obtained due to the round shape of the notch and due to the sideward stretch acting on the sheet metal.
As it can be seen in Figure 22 and much better in Figure 23, the edges 47 upper and lower mate with each other perfectly. The end section 41 of the joining line of the two edges 47 is very narrow, in fact equal to the thickness of the sheet metal. This fact along with the perfect round shape of the edges 47, reduces remarkably the critical welding point usually found in this position with the techniques of the prior art.
Welding along the mating edges 47 of the hollow body 48 is very easy with any suitable welding technique, without critical points and the end sections 41 are closed without additional operation.
Figure 24 show the tubular extension thus obtained, perfectly round, with the edges 47 and the end sections 41 welded and liquid-tight. Also the joining bored small cylinder 24 can be seen in Figure 24, as it is used to connect the tubular element (not shown). The perfect round shape of the tubular extension facilitates also this connection.
Another way to obtain a perfect seal is shown in Figures 25 and 26. According to this different way, the notches 53 in the hollow body 58 are wider and longer, determined with respect to the number and diameter of the tubular extensions, in a way such as to leave a free space 54 between the edges 57. The free space 53, that is clearly visible in Figure 26, is then filled with a metal insert 55, suitably "U"-shaped, as to match the width and the curved shape of the free space.
After insertion of the metal insert 55, the joining lines 53 (only one has bee indicated in Figure 26 for clarity) are welded by suitable welding technique. For instance, a pastry fusible material can be applied to the joining line when the tubular element are fitted on the joining cylinders 24. Then the complete group can be inserted into the oven so that both the metal insert 55 and the tubular elements are welded to the hollow body 58.
This way, the metal insert is welded to the edges 57 closing the bottom of the head element, in a single operation along with the connection of the tubular elements.
Consequently, the objects listed in the introduction have been obtained by the method for producing head elements and the head element described above.
The head element is produced in a single body, by more pressing steps, without the drawbacks resulting from the fusion procedure and without the necessity to weld two semi-shells to each other, or other elements of considerable dimensions for the head element closing.
This feature allows to reduce the production time and costs and to obtain a product of high quality.
The head element obtained by the above mentioned method is aesthetically pleasant, which allows to reduce as much as possible other finishing operations.

Claims

A method for producing head elements for heaters, the method including:
preparing a piece of a sheet metal (1);

deep drawing said sheet metal piece (1) to obtain a hollow molded piece (2), defined by a base wall (3), sides (4,5,14,15) joined to and surrounding the base wall and forming an open side (6);

cutting the sides (4,5,14,15) along the open side (6), to define a hollow body (8, 48, 58) with an edge (9), which is uniform and extends around said open side (6);

making a lateral through aperture (12) on two opposite sides (4,5) to obtain apertured opposite sides;

providing connection means (25) around each lateral through aperture (12);

introducing at least two cores (18) into said edge (9) of the open side (6);

press-shaping the open side (6) of said hollow body to obtain depressed areas (49) between said cores (18);

making one "V"-shaped notch (16, 46, 56) in each one of said depressed area (49) on the apertured opposite sides (4,5), along said edge (9), the notch being wider at said edge;

press-shaping the notch edges (17, 47, 57) of the notches (16, 46, 56) around each said core (18), so as to close the sheet metal around said cores (18) to obtain tubular extensions in the area of said edge (9);

removing said cores (18) from the hollow body;

welding of said edges (17, 47, 57) so as to obtain a series of tubular extensions (13) separated from each other.
Method according to claim 1, characterized in that the maximum width (W), the length (L) and the radius (R) at the inner part of the notches (46) are such, in relation to the number and the diameter of the tubular extensions, that the relevant edges (47) after press-shaping mate perfectly with each other.
Method according to claim 1, characterized in that the maximum width (W), the length (L) and the radius (R) at the inner part of the notches (56) are such, in relation to the number and the diameter of the tubular extensions, that the relevant edges (77) after press-shaping, leave a free space (54) between them, into which a "U"-shaped metal insert (55) is fitted and then welded to said edges (47).
Method, according to any of the claims 1 to 3, characterized in that the fastening means (25) are obtained on each lateral through aperture (12) by welding a threaded ring (26) around the lateral through aperture (12).
Method, according to any of the claims 1 to 3, characterized in that the fastening means (25) are obtained on each lateral through aperture (12) by outwards pressing a circular crown (27), extending around each lateral through aperture (12), so as to form a protruding edge (31) on each of said apertured sides (4,5).
Method, according to claim 5, characterized in that a threaded ring (38) is placed inside the seat defined by said protruding edge (31).
Method, according to claim 5 or 6, characterized in that said outward pressing is obtained by inserting a flat core (28) into said hollow body (8, 48, 58), through the open side (6), before the tubular extensions (13) are made, the flat core (28) including a floating element (29) matching each lateral through aperture (12) and pushed outwards alternately in opposite directions, while on the outer part of the hollow body (8, 48, 58) a die (30) is situated.
Method, according to any of the claims 1 to 7, characterized in that the tubular elements (23) are coupled to said head element by inserting a small bored cylinder (24) into each tubular extension (13), said small cylinder (24) having a groove made along its circumference with a ring (34) of fusible material inserted therein, by fitting the head of each tubular element (23) on the part of the small bored cylinder (24) protruding from the relevant tubular extension (13), and by heating the connection area between each tubular element (23) and the head element near the tubular extensions, so that the ring (34) of fusible material melts and the head element is welded to the tubular elements (23) by brazing.
Method, according to claim 3, characterized in that, after that the metal insert 55 has been fitted into said free space (54), the tubular elements (23) are coupled to said head element by inserting a small bored cylinder (24) into each tubular extension (13), said small cylinder (24) having a groove made along its circumference with a ring (34) of fusible material inserted therein, by fitting the head of each tubular element (23) on the part of the small bored cylinder (24) protruding from the relevant tubular extension (13), and by heating, after a pastry fusible material has been applied to the joining lines (53) between the edges (57) and the relevant metal inserts (55), the connection area between each tubular element (23) and the head element near the tubular extensions, so that the ring (34) of fusible material melts and the head element is welded to the tubular elements (23) by brazing and so that, at the same time, the pastry fusible material melts and the metal inserts (55) are welded to the relevant edges (57).
Head element for heaters as obtained by the method of claim 1, made in a single hollow body (8, 48, 58), defined by a base wall (3), sides (4,5, 14,15) joined to and surrounding the base wall (3), at least two tubular extensions (13) extending from said hollow body (8, 48, 58), with at least one lateral through aperture (12) made on two opposite sides (4,5) defining two apertured sides, characterized in that said body is obtained from a single part of a deep-drawn sheet metal, in which, said tubular extensions (13) are delimited by press-shaped edges (47, 57) of notches (16, 46, 56) made along an open side (6), opposite to said base wall (3) of said hollow body (8, 48, 58) and joined to each other to separate said tubular extensions (13).
Head element according to claim 10, characterized in that between counter-facing edges (57) of the hollow body (58) a metal insert (55) is fitted filling a free space (53).
Head element according to claim 11, characterized in that said metal insert (55) is not welded to the adjoining edges (57), as it is then welded to said edges (57) while welding, at the same time, tubular elements to said tubular extensions.
Head element according to one of claims 11 or 12, characterized in that the metal insert (55) is welded to the same edges (57) to join these edges.
Head element according to any of the claims 11 to 13, characterized in that the metal insert (55) is "U"-shaped.
Head element according to any of the claims 11 to 14, characterized in that the metal insert (55) is welded to the notch edges (57) by brazing.
Head element according to any of the claims 10 to 16, characterized in that fastening means (25) are provided around each lateral through aperture (12).
Head element, according to claim 16, characterized in that notches (16), spaced apart and surrounded by the molded flanges (17), are made on each of said apertured opposite sides (4,5), along said edge (9), to delimit three tubular extensions (13).
Head element, according to claim 16, characterized in that the fastening means (25) on each lateral through aperture (12) are constituted by a threaded ring (26) fastened to a relative apertured side (4,5).
Head element, according to claim 16, characterized in that the fastening means (25) on each lateral through aperture (12) include a circular crown (27), surrounding the lateral through aperture (12) drawn outwards to form a protruding edge (31).
Head element, according to claim 19, characterized in that a threaded ring (38) is placed inside the seat defined by said protruding edge (31).