WO2001019548A1

WO2001019548A1 - Fabrication of radiators

Info

Publication number: WO2001019548A1
Application number: PCT/GB2000/002598
Authority: WO
Inventors: John Alfred White
Original assignee: Ford Motor Company Limited
Priority date: 1999-09-16
Filing date: 2000-07-05
Publication date: 2001-03-22
Also published as: GB9921820D0; GB2354299A

Abstract

This invention relates to the fabrication of radiators (10) for use in motor vehicles, in particular to the formation of water tight joints between header panels (14) and radiator tubes (12) which are located in holes within the header panel (14). The tubes (12) are expanded by inserting an expansion finger (24) with a tapering end into the tubes (12) in order to reduce the gap between the header panels (14) and the tube walls before a brazed joint is formed. The tubes (12) are prevented from being pulled out of alignment when the fingers (24) retract by retaining members (32) in sliding contact with the fingers (24).

Description

FABRICATION OF RADIATORS

This invention relates to the fabrication of radiators for use in motor vehicles, in particular to the formation of water tight joints between radiator sections.

In most radiators, parallel tubes though which cooling fluid can be circulated are kept in position at each end by a pair of header plates arranged normal to the length of the tubes. The ends of the tubes pass through holes in the header plates and a water tight joint must be formed where the tube wall meets the header plate. The joint can be formed by brazing but before the brazing can be carried out, the tube ends should be expanded in order to reduce the gap between the outer surface of the tube wall and the inner edge of holes in the header panels .

The ends of the tubes are normally expanded by inserting two metal fingers into the ends of each tube, the fingers being spaced apart with a retaining member between them, the retaining member extending across the width of the tubes so that the tubes are prevented from being pulled back when the fingers retract from within the tubes. However, the tubes may not always be sufficiently expanded in the region between the two fingers, and the resulting expanded cross section may have a waist where insufficient expansions has occurred, giving rise to the so-called peanut effect .

The peanut effect is undesirable because it may give rise to an excessive gap between a tube wall and the inner edges of a hole in the header plate, making it more difficult to form a good brazed joint. The peanut effect is particularly undesirable for tubes with a dimpled surface, since the gap due to the peanut effect can be increased if it occurs where there is dimple in the tube wall.

According to a first aspect of the invention, there is provided an expander assembly for expanding the end portion of one or more open ended tubes, the expander assembly comprising at least one finger, the or each finger having a tapering portion with at least one slanting face for inserting into a tube, and at least one retaining member adapted to retain the tube when the finger is retracted from within the tube, characterised in that the retaining member is biased into sliding contact with the finger such that the retaining member does not obstruct the orifice of the tube when the finger is inserted into the tube.

It will be understood that the slanting face of a finger will be orientated so that the finger becomes wider with increasing distance away from its end, the size of the fingers in relation to the tubes being chosen so that inserting a finger into the orifice of a tube enlarges the cross section of that tube.

Although the expander assembly may comprise a single retaining member, for simplicity the invention will hereinafter be described in terms of an expander assembly with two retaining members . Preferably, the retaining members will be spaced apart to reduce the risk of a tube tilting when it is retained by the retaining members.

Because the retaining members do not obstruct the orifice of the tubes, the fingers can extend across at least a substantial part of the cross sectional area of the tubes when inserted into the tubes . This reduces the peanut effect and make it easier to subsequently form a water tight brazed joint around the tubes.

In order to expand the tube ends on one side of a radiator at the same time, the expander assembly will preferably comprises a plurality of fingers, the number of fingers corresponding to the number of tubes in the radiator.

Preferably, guiding means will be provided that guide the movement of the fingers along the direction of their long axes and prevent movement of the retaining members in a direction parallel to the direction of movement of the fingers. Since the retaining members are in sliding contact with each finger, the retaining members can engage with the edge of a tube wall if that tube is pulled back when the finger retracts, so that the tube will separate from the finger.

Preferably, the surface of the retaining member that engages with the ends of the tube walls will be flat, so that the ends of the tubes remain in alignment with each other after the fingers have retracted.

Each finger will preferably have at least two slanting faces so that as a finger enters the end portion of a tube, the end portion will be expanded gradually.

Preferably, one of the retaining members will be in sliding contact with a slanting face on one side of fingers, and the other retaining member will be in sliding contact with a slanting face on the opposite side of the fingers, so that the retaining members obstruct the orifices of the tubes when the fingers are not inserted, and when the fingers are inserted, the retaining members move away from each other so as not to obstruct the orifices of the tubes.

Such an arrangement allows the ends of the tubes to be placed against the retaining members and be thereby aligned before the fingers are inserted into the tubes.

Preferably, each retaining member will be retained in a groove provided by the guiding means, the groove being orientated so as to guide the movement of the retaining members in direction transverse to the direction of movement of the fingers.

For convenience, the retaining members will preferably be biased by a spring situated at the bottom of each groove .

According to a second aspect of the invention, there is provided a method of assembling a motor vehicle radiator, the method comprising the steps of expanding the end portion of a plurality of open ended tubes located in a header panel of a motor vehicle radiator with an expander assembly tool comprising a plurality of fingers each with a tapering portion having at least one slanting face for inserting into a tube, wherein the tapering portion has a smaller cross section than the unexpanded tube at one end and a larger cross section than the unexpanded tube at the other end, and at least one retaining member adapted to retain the tubes when the fingers are retracted from within the tubes, characterised in that the or each retaining member is biased into sliding contact with the fingers and the retaining member does not obstruct the orifice of a tube when the fingers are inserted into the tubes .

The invention will now be further described, by way of example, with reference to the accompanying drawings in which:

Figure 1 is shows a schematic cross section though a radiator assembled according to the invention;

Figure 2 is a schematic cross sectional view of a header tool with part of a radiator tube;

Figure 3 is a schematic cross sectional view though the line II- II in Figure 2 showing three tubes when the fingers of the header tool are partly inserted in the tube ;

Figure 4 is a view corresponding to Figure 3 but where the fingers are more fully inserted into the tubes; and,

Figure 5 is a schematic plan view of an expander tool with fingers and part of a radiator.

Figure 1 shows radiator 10 after it has been assembled, the radiator having a set of straight parallel tubes 12 which at each end pass though holes 13 in header plates 14 aligned parallel to one another. The header plates each have a cover 16 which together with header plates 14 and the tubes 12 forms a continuous enclosure . When the radiator 10 is in use, cooling water enters through an inlet 18 on one cover and passes through the tubes 12 into the region bounded in part by the other cover 16, leaving the radiator through an outlet 20 on the other cover.

The radiator 10 is assembled by passing the tubes 12 through the holes 13 in the header plate 14, the holes 13 being slightly larger than the cross sectional area of the tubes 12 to allow to tubes to be easily inserted into the holes 13.

With the tubes located in the header plate 14 but without the cover 16 in place, the end portion 15 of each tube 12 is expanded in cross section. The expansion of the end portion 15 of a tube 12 locally increases the cross sectional area of the tube 12 such that the outer surface of the tube wall makes contact with the inside edge of the hole 13 in the header panel 14. The flared edges of the tubes that result from the expansion then act to retain the header in position against side supports located between the two headers (not shown) .

A header tool 30 is used to expand the tubes 12, the header tool comprising an expander tool 26 on which fingers 24 are arranged in a row, the fingers 24 extending in parallel from the expander tool 26 with the spacing between them chosen to match the spacing between the tubes of the radiator that is to be assembled as shown in Figure 5.

The header tool has parallel spaced apart ridges 40, between which the tubes 12 can locate so as to be aligned with the fingers 24.

In order to expand the tubes 12, expander tool 26 moves towards the tubes 12 in the direction indicated by the arrow in Figure 2, and the header tool 30 guides the fingers 24 into the tube orifices 28.

The fingers 24 have slanting sides and the cross sectional area of a finger increases with increasing distance from the end of the finger, so that when the fingers are inserted into the end portions 15 of the tubes 12, the walls of the end portions 15 are expanded smoothly in a cone like fashion.

When viewed in cross section, the tubes 12 are elongate 5 in one direction. The fingers 24 have a cross sectional area that is elongate in the same direction as the tubes 12. Hence when a finger 24 is fully inserted into an end portion 15 of a tube 12, its cross sectional area in a plane adjacent to the end of the tube will substantially

10 span the enlarged cross sectional area of the tube 12 in that same plane. This will provide a more uniform outward force on the inside surface of the tubes, which will result in the tube wall being more uniformly expanded and reduce the likelihood of the peanut effect.

15

To help prevent the tubes from significantly being pulled back out of alignment by the fingers 24 when the fingers retract from within the end tube portions 15, the header tool 30 has retaining members 32, shaped like bars, which

20 overlap the ends of the tubes 12 when looking at the tubes in cross section as shown in Figures 3 and 4. The retaining members are located in a groove 34 within the header tool 30 and are biased by springs 36 into sliding contact with slanting side faces 38 of the fingers 24. The

25 engagement of the retaining members 32 in the groove 34 only allows the retaining members 32 to move in a direction normal to the length of the tubes 12, so the retaining members 32 are not displaced by the movement of the tubes 12.

30

As the fingers 24 move into the orifices 28 of the tube

„ end portions 15, the retaining members 32 are pushed away from one another by the movement of the fingers 24. The sides of the retaining members in sliding contact with the

35 fingers 24 have the same angle of slant as the faces of the fingers 24 which they contact, so that the sides of the retaining member 42 facing the tubes remains adjacent to the finger 24 as it moves. Hence even when a finger 24 is fully inserted into the end portion 15 of a tube 12, and the end of the tube walls are in contact with the slanting faces of the finger, the retaining members are able to engage with the edge of the tube wall, (which is typically 0.5 mm thick) , thereby reducing the distance by which a tube can be pulled out of alignment when the fingers retract.

To help balance the forces experienced by the tubes 12 along their long axes as they are being expanded, a header tool 30 can be used on each side of the radiator 10 and the fingers 24 can be inserted and retracted substantially simultaneously from opposite ends of each tube 12.

After the tubes 12 have been expanded in the way described above, a brazed joint can be formed where the tube walls meet the header plate 14 so that cooling water does not leak between the tubes 12 the header panel 14, and the subsequent assembly stages of the radiator can be carried out .

Claims

Claims :

1. An expander assembly (30) for expanding the end portion of one or more open ended tubes (12) , the expander assembly (30) comprising at least one finger (24) , the or each finger (24) having a tapering portion with at least one slanting face for inserting into a tube (12) , and at least one retaining member (32) adapted to retain the tube (12) when the finger (24) is retracted from within the tube (12) , characterised in that the retaining member (32) is biased into sliding contact with the finger (24) such that the retaining member (32) does not obstruct the orifice of the tube (12) when the finger (24) is inserted into the tube (12) .

2. An expander assembly (30) as claimed in Claim 1, wherein the or each finger (24) becomes wider with increasing distance away from its end.

3. An expander assembly (30) as claimed in Claim 1 or Claim 2, wherein the expander assembly (30) has two spaced apart retaining members (32) .

4. An expander assembly (30) as claimed in any previous claim, wherein the expander assembly (30) comprises a plurality of fingers (24) .

5. An expander assembly (30) as claimed in any previous claim, wherein guiding means (34) are provided that guide the movement of the fingers (24) along the direction of their long axes and prevent movement of the retaining members (32) in a direction parallel to the direction of movement of the fingers (24) .

6. An expander assembly (30) as claimed in any previous claim, wherein the surface of the or each retaining member (32) that engages with the ends of the tube walls is flat.

7. An expander assembly (30) as claimed in any previous claim, wherein each finger (24) has at least two slanting faces .

8. An expander assembly (30) as claimed in any of Claims 3 to 7, wherein one of the retaining members (32) is in sliding contact with a slanting face on one side of fingers (24), and the other retaining member (32) is in sliding contact with a slanting face on the opposite side of the fingers (24) , so that the retaining members (32) obstruct the orifices of the tubes (12) when the fingers (24) are not inserted, and when the fingers (24) are inserted, the members (32) move away from each other so as not to obstruct the orifices of the tubes (12) .

9. An expander assembly (30) as claimed in any previous claim, wherein the or each retaining member (32) is retained in a groove (34) provided by the guiding means, the or each groove being orientated so as to guide the movement of the retaining member (32) in direction transverse to the direction of movement of the fingers (24) .

10. An expander assembly (30) as claimed in any previous claim, wherein the or each retaining member (32) will preferably be biased by a spring (36) situated at the bottom of the or each groove.

11. A method of a assembling a motor vehicle radiator, the method comprising the steps of expanding the end portion of a plurality of open ended tubes (12) located in a header panel of a motor vehicle radiator with an expander assembly tool (30) comprising a plurality of fingers (24) each with a tapering portion having at least one slanting face for inserting into a tube (12) , wherein the tapering portion has a smaller cross section than the unexpanded tube (12) at one end and a larger cross section than the unexpanded tube (12) at the other end, and at least one retaining member (32) adapted to retain the tubes (12) when the fingers (24) are retracted from within the tubes (12) , characterised in that the or each retaining member (32) is biased into sliding contact with the fingers (24) and the retaining member (32) does not obstruct the orifice of a tube (12) when the fingers (24) are inserted into the tubes (12) .