IE51519B1 - Method of and apparatus for manufacturing heat exchangers - Google Patents

Description

The present invention relates to heat exchangers and in particular to heat radiators of the kind in which a plurality of mutually parallel flat heat exchange tubes are connected between a pair of header pipes, and is concerned with a novel and automated method of and apparatus for manufacturing such radiators.

The invention accordingly provides a method of manufacturing heat exchangers, the method comprising the following steps: holding two lengths of header piping in mutually parallel spaced apart relationship and feeding the header piping in steps through a work station; locating a heat exchange element in contact with the header piping so that an aperture adjacent each end of the heat exchange element is aligned with an aperture in the contiguous length of header piping; welding each end of the heat exchange element to the header piping to provide a mechanical joint and seal between the piping and the heat exchange element and so as to enable fluid communication between the interior of the piping and the heat exchange element; and advancing the piping and connected heat exchange element beyond the connection work station.

Advantageously, the method includes the steps of pre-forming and pre-cleaning the apertures in the header 51518 - 3 piping to facilitate resistance welding of the heat exchange elements to each length of header piping.

In a further step in the method, the header piping, to and between which heat exchange elements have been connected, is cut into predetermined lengths at a subsequent cutting station to form discrete radiator assemblies.

The header piping which bends at the connection station, during connection of a heat exchange element to and between the header piping, is corrected by deliberately induced contra bending.

Advantageously, baffles are inserted into the header piping, between selected heat exchange elements, for routing the flow of heat exchange fluid through the heat exchange elements, the baffles being preferably of resiliently deformable non-perishable material such as silicone rubber. Each baffle may have a hole into which is inserted a tool having a length greater than the length of the hole, the tool being used to push the baffle along the pipe to the desired location.

The invention also provides apparatus for manufacturing heat exchangers, the apparatus comprising; holding means for holding two lengths of header piping in mutually parallel spaced apart relationship and for feeding the header piping in steps through and beyond a work station; 51518 - 4 locating means for positioning a heat exchange element relative to the header piping so that an aperture adjacent each end of the heat exchange element is aligned with an aperture in the contiguous length of header piping; and welding means at the work station for welding each end of the heat exchange element to the contiguous header piping to provide a mechanical joint and seal between the piping and the heat exchange element and so as to enable fluid communication between the interior of the piping and the heat exchange element.

The invention further provides heat exchangers made by the above method or apparatus.

The invention also provides a double heat exchanger 15 comprising two heat exchangers each provided with one generally semi-circular section header pipe, the two semi-circular header pipes being joined back-to-back such that the two header pipes have a generally circular composite section, the double heat exchanger being assembled from two heat exchangers made by the method or apparatus of the invention, and being provided with a single circular fluid connection at each end of the joined header pipes, providing fluid access and exits to each half of the joined header pipe. 51518 - 5 The invention will now be described more particularly, by way of example, with reference to the accompanying drawings, in which: Figures la, lb and lc are front elevation, end elevation and plan views respectively of a column radiator; Figures 2a and 2b, which are to a larger scale, are sectional end and sectional front elevations respectively of the upper left hand corner of the column radiator of Figure 1; Figures 3a and 3b are schematic plan and side elevation views respectively of apparatus for manufacturing column radiators by the method of the invention; Figures 4a and 4b are side and end elevations respectively, to an enlarged scale, of a detail of the apparatus shown in Figure 3, namely the welding work station; Figure 5 illustrates, to an enlarged scale, a detail of the apparatus shown in Figure 3, namely a work station for reverse bending of piping bent in the welding work station, Figure 5a showing side and end elevations of the station and piping before reverse bending and Figure 5b showing similar views during reverse bending, the bending being shown exaggerated for purposes of illustration; - 6 Figures 6a, 6b and 6c are rear, side and front elevations respectively of a baffle; Figure 7 is a sectional side elevation of the baffle and baffle insertion tool; Figures 8a to 8e illustrate successive stages in the formation of a double column radiator from two single radiators made by the method of the invention, and each show an end elevation and a plan view of a top corner of the double radiator; Figures 9a and 9b are sectional plan views, to an enlarged scale, of the top corners of the double column radiator illustrated in Figure 8, showing a socket on the header before and after welding respectively; Referring again to Figures la, lb, lc, 2a and 2b of the drawings, there is shown in those figures a column radiator comprising headers 1 connected by a series of heat exchange elements 2, which are made from flat metal tubes closed and sealed at each end.

Corresponding water entry and exit apertures 3 (see Figures 2a and 2b) are provided on the headers 1 and on the curved part of the side walls of the heat exchange element 2.

A method of and apparatus for manufacturing the heat exchangers, including assembling the heat exchange elements 2 to the headers 1, will now be described.

During the description, it will be assumed that the heat 51518 - 7 exchange elements 2 have already been prepared from flat metal tubes.

Figures 3a and 3b illustrate the method and apparatus. Two long lengths of piping 10 are fed to the apparatus in mutually parallel spaced apart relationship. The spacing between the lengths 10 is set to accommodate a given length of heat exchange element 2. One side of the apparatus is movable so that the spacing can be adjusted, to enable batches of heat exchange elements 2 of different lengths to be assembled to headers 1 to give assemblies of different width between headers. One of the heat exchange elements 2 from the batch can be used as a direct measure for setting the width of the apparatus.

The lengths of piping 10 are then advanced automatically through the apparatus, step-by-step, one heat exchange element pitch at a time. This step-bystep advance is achieved by means of a feed system using fixed clamps 16, 17 and 18 to hold the piping between steps and moving clamps 19 and 20 to effect the steps.

Between steps, when the lengths of piping 10 are stationary, a number of operations are carried out in a sequence of workstations.

In the first pair of workstations 21, apertures 3 for the entry and exit of fluid are drilled in the piping 10. These apertures 3 should be at least 5 mm in diameter. In the next pair of workstations 22, the region of the piping 10 in which the fluid apertures 3 have been formed, is cleaned in preparation for subsequent resistance welding. Cleaning is effected by means of rotating wire brushes 22a which descend on the surface of the piping 10.

In the next pair of workstations 23, a heat exchange element 2 is brought into contact with the lengths of piping 10, with the apertures 3 on the heat exchange element 2 in alignment with the apertures 3 in the lengths of piping 10, between the throats of two resistance welding presses 24, one at each end of the heat exchange element 2. The heat exchange element 2 may be manually loaded into the apparatus or may be fed automatically from the apparatus which prepares it, and which is described in more detail below.

In the case of manual loading, the heat exchange element 2 is loaded into position in workstation 23 as indicated by arrows 25 in Figures 3a and 3b. The heat exchange element is held with its flat faces vertical by means of the fixed entry guide ramps 26 and the vertical guide pins 27. The pins 27 are extended, as shown in Figure 3b, during loading and positioning of the heat exchange element 2 but are retracted after the heat exchange element 2 is welded to the piping 10 to allow the assembly move forward in the apparatus. . - 9 In the case of automatic loading, the heat exchange element 2 is automatically transferred from the apparatus for preparing the heat exchange elements to the work station 23 by means of either a robot or by a special purpose conveying device which discharges the heat exchange element 2 onto the fixed guide ramps 26 and allows the heat exchange element 2 to fall into the correct position.

Figure 3b shows a heat exchange element which has just entered work station 23. The welding press has both its upper electrode 30 and its lower electrode 31 withdrawn. Figures 4a and 4b show the same heat exchange element 2, but with the electrodes 30 and 31 closed. The lower electrode 31 ascends to meet the piping 10, the upper electrode 30 descends onto the heat exchange element 2, the side plate 32 of the upper electrode 30 closes inwards to precisely locate and to make better electrical contact with the heat exchange element 2, and the resistance weld is then effected.

As the resistance weld cools, it causes the piping 10 to bend concavely in the region of the heat exchange element 2, as depicted in Figure 5a. This distortion can be removed by bending the piping 10 in the opposite direction, also as part of the step-by-step process. This reverse or corrective bending can be very conveniently carried out in the welding press using the - 10 fixed clamps 17 and 18 to hold the piping 10 and using the bottom electrode 31 to push the piping 10 upwards thereby bending it in the opposite direction, as shown in Figure 5b. When released, the piping 10 springs back to its original straight condition.

Thus there emerges from the machine, step-by-step, an assembly comprising two long lengths of piping 10 connected by a series of heat exchange elements 2.

The emerging assembly is cut into suitable lengths for heat exchangers, such as central heating radiators, by a pair of rotating saw blades 33.

Referring now to Figures 6 and 7, the next stage before closing the open ends of the headers 1 is to insert baffles, if required, into the headers 1 to route the hot water through the heat exchange elements 2. The above-described drilling and resistance welding of the piping 10 may preclude subsequent insertion of conventional metal baffles into the resulting headers 1. (In known manual production methods the metal baffles are inserted before the drilling and resistance welding). Baffles 40 made of silicone rubber are used instead. Silicone rubber is flexible and water resistant. Because of its flexibility, the baffle 40 may be pushed past obstacles inside the header to reach the desired location. The baffle 40 comprises a cylindrical piece of rubber provided with an axial blind - 11 hole 40a. The baffle 40 is pushed along the header 1 by means of a spigot 41 inserted in the blind hole 40a.

The spigot 41 is used to push the baffle 40 along the inside of the header 1. If the baffle 40 encounters an obstacle, the spigot 41 causes the baffle 40 to stretch axially and thereby contract radially thus easing passage past the obstacle. The spigot 41 is made longer than the blind hole 40a and is provided with a shoulder 41a to prevent it inadvertently breaking through the baffle 40.

Finally, the cut ends of the radiator headers 1 are closed. Where the headers are round in section, they are plugged with turned steel plugs (not shown) which are tapered and are a drive fit in the ends of the headers 1. The plugs are driven into position by means of a hand held powered impact hammer. The plugs are then sealed in position by, for example, TIG welding. The plugs may incorporate entry, exit or air vent tappings.

Referring now to Figures 8 and 9, double column radiators may be made by the above method. The method is carried out as described above, but using piping which is semi-circular in section. Figure 8a shows two single column radiators which are to be joined and interconnected to form a double radiator. Semi-circular section headers 1 are used at both the top and bottom of 51518 - 12 the radiators. The radiators are arranged with the semi circular headers back to back as shown in Figure 8b.

The seam 50 between the ends of the headers 1 is then sealed as shown in Figure 8c. Sealing is effected by welding. The weld is continued a short distance along the length of the headers 1. A steel plug or socket 51 is then positioned at the end of the headers 1. As shown in Figure 8d, the plug 51 comprises a shallow cylindrical bore which locates over the end of the headers 1. The plug 51 is then welded circumferentially to the headers, as shown in Figure 8e. Care is taken to ensure that the circumferential weld meets the lengthwise continuation of the weld between headers.

The above described combination of welds and plug ensure a fluid tight radiator end, and a balanced entry and exit of fluid to both sections of the double radiator.

Alternatively, a double column radiator may be made by connecting heat exchange elements 2 to both sides of the two lengths of piping 10 as they advance through the apparatus. 51518

Claims (11)

1. A method of manufacturing heat exchangers, the method comprising the following steps: holding two lengths of header piping in mutually parallel spaced apart relationship and feeding the header piping in steps through a work station; locating a heat exchange element in contact with the header piping so that an aperture adjacent each end of the heat exchange element is aligned with an aperture in the contiguous length of header piping; welding each end of the heat exchange element to the header piping to provide a mechanical joint and seal between the piping and the heat exchange element and so as to enable fluid communication between the interior of the piping and the heat exchange element; and advancing the piping and connected heat exchange element beyond the connection work station.

2. A method according to Claim 1, in which the apertures in the header piping are pre-formed and pre-cleaned to facilitate resistance welding of the heat exchange element to each length of header piping.

3. A method according to any one of Claims 1 or 2, in which.the header piping, to which heat exchange elements have been connected, is cut into predetermined lengths at a subsequent cutting station to form discrete radiator assemblies. - 14

4. A method according to any one of the preceding claims, in which the header piping which bends at the connection work station, during connection of a heat exchange element to and between the header piping, is 5. Corrected, at the same or subsequent work station, by deliberately induced contra bending.

5. A method according to any one of the preceding claims, in which baffles are inserted into the header piping, between selected heat exchange elements, for 10 routing the flow of heat exchange fluid through the heat exchange elements, the baffles being preferably of resiliently deformable non-perishable material such as silicone rubber, and each baffle having a hole into which is inserted a tool having a length greater than the length 15 of the hole, the tool being used to push the baffle along the pipe to the desired location.

6. Apparatus for manufacturing heat exchangers, the apparatus comprising holding means for holding two lengths of header 20 piping in mutually parallel spaced apart relationship and for feeding the header piping in steps through a work station; locating means for positioning a heat exchange element relative to the header piping so that an aperture 25 adjacent each end of the heat exchange element is aligned 51518 - 15 with an aperture in the contiguous length of header piping; and welding means at the work station for welding each end of the heat exchange element to the continuous header 5 piping to provide a mechanical joint and seal between the piping and the heat exchange element and so as to enable fluid communication between the interior of the lengths of piping through the heat exchange element.

7. Heat exchangers made by a method or apparatus 10 as claimed in any one of the preceding claims.

8. A double heat exchanger comprising two heat exchangers each provided with a generally semi-circular section header pipe, the two semi-circular header pipes being joined back-to-back such that the two header pipes 15 have a generally circular composite section, the double heat exchanger being assembled from two heat exchangers as claimed in Claim 7 and being provided with a single circular fluid connection at each end of the joined header pipes, providing fluid access and exits to each half of 20 the joined header pipe.

9. A method of manufacturing a heat exchanger, substantially as herein described with reference to the accompanying drawings. -Ιδιο. Apparatus for manufacturing a heat exchanger, substantially as herein described with reference to and as shown in the accompanying drawings.

10.

11. A double column radiator substantially as herein 5 described with reference to and as shown in the accompanying drawings. MACLACHLAN & DONALDSON Applicant's Agents 47 Merrion Square DUBLIN 2. BRIAN FRANCIS MOONEY 1/9 SHEET ONE