Apparatus and method for producing an end closure

Abstract: The invention relates to an apparatus for producing an end closure for a pipe (2) which forms part of a heat exchanger, said apparatus comprising: a frame (4), with a first side (6) and a second side (8) situated opposite the first side, and a tubular through-channel (10) whose opening (12) on said first side is delimited by a side surface (16) extending around the opening (12), it being possible for a pipe (2), which is intended to be closed, to be introduced into the tubular channel (10) from said second side (8); a press tool (32) which is arranged to execute a reciprocal motion through the channel (10); the press tool (32) being arranged, by virtue of its forwardly directed movement, to press an end closure blank (38) into the opening (12) of the channel (10). The invention also relates to a method for producing an end closure for a pipe (2) which forms part of a heat exchanger, said method comprising the measures of introducing a pipe (2) intended for closure into a channel (10) in a frame (4) in accordance with the above, and of pressing an end closure blank (38) into the through-channel (10) and pushing the blank (38) through the channel (10) and on into the pipe (2), with the blank, by engagement with the side surface (16) of the frame (4) and thereafter with the inner limit surfaces of the channel (10), being shaped to give a cup-shaped end closure which, with its aperture directed outward from the pipe end, fits into the latter.

Description: The invention relates to an apparatus for producing an end closure for a pipe which forms part of a heat exchanger and a method for producing an end closure for a pipe which forms part of a heat exchanger. Heat exchangers are often constructed in the form of a heat exchanger stack with inlets and outlets for a heat exchanger fluid, these being made of aluminum. The heat exchanger stack often consists of a number of pipes which are placed one on top of the other, or one behind the other, and which between them have surface-increasing elements or so-called ranks. In certain types of heat exchangers, such as an oil cooler of the type which is intended to be placed inside the tank belonging to a conventional vehicle radiator, it is necessary to close the end apertures of the pipes. One means of producing an end closure is to introduce into the end aperture a solid aluminum block which is arranged to bear sealingly against the insides of the end aperture. However, such a solution has a number of disadvantages. A solid block entails considerable material consumption, and since the costs of material constitute a major part of the overall costs, this is something to be avoided. Moreover, the substantial difference in material thickness between the solid block and the end aperture means that soldering problems occur. There is therefore a need for a solution which is an improvement on the prior art. One object of the invention is to provide an apparatus and specify a method for producing an end closure for a pipe which forms part of a heat exchanger, which end closure permits a low consumption of material and can be connected to the pipe by hard soldering. Another object of the invention is to produce an apparatus and specify a method for producing an end closure which is self-fixing in the end aperture of the pipe. According to a first aspect of the present invention there is provided an apparatus for producing and inserting an end closure for a pipe which forms part of a heat exchanger, said apparatus comprising: a frame which has a first side and a second side situated opposite the first side, and a tubular channel for an end portion of said pipe, said channel running from the first side to the second side and having an opening on said first side which is delimited by a side surface extending around the opening; a press tool and means for causing said press tool to execute a reciprocal motion through the channel from said first side of the frame; the press tool being arranged, by virtue of its forwardly directed movement, to press an end closure blank into said opening of the channel and to form a cup-shaped end closure by engagement between the end closure blank and said side surface of the frame, and thereafter to push the cup-shaped end closure into the channel and into a pipe introduced from said second side, with the aperture of the end closure being directed outward from the pipe end, whereby the end closure fits into the pipe end. According to a second aspect of the present invention there is provided a method for producing an end closure according to claim 7. Preferred features of the embodiments are set out in the dependent claims. The invention provides that the end closure can be pushed into the end aperture of the pipe with press-fitting, which permits self-fixing of the end closure in the pipe, which fact is of great advantage in the subsequent hard-soldering operation. The special shape of the end closure also means that the solder seam between the end closure and the inside of the pipe is long, which on the one hand ensures a strong connection and on the other hand ensures a good closure and thus sealing. The sealing requirements are very stringent, especially in the abovementioned application, where an oil cooler is placed in the tank on a vehicle radiator. It will be appreciated that there can be devastating consequences if liquid in the form of water and glycol is allowed to leak into the oil cooler and mix with the oil. A preferred embodiment of the invention will now be described with reference to the drawings, in which: Figure 1 is a plan view of a metal tape and two end closure blanks, which are connected to the metal tape; Figure 2 is a side view, partly in section, of an apparatus, where certain parts have been cut away for reasons of clarity; Figure 3a is a view, from straight in front, of a finished end closure; and Figure 3b is a side view of the finished end closure in Figure 3a. In the drawings, like reference numerals refer to like parts. Figure 2 shows an apparatus for producing an end closure for an aluminum pipe 2, which apparatus has a frame 4 with a first side or front side 6 and a second side or rear side 8, where the rear side 8 is situated opposite the front side 6, as is seen clearly from Figure 2. The frame is furthermore designed with a substantially rectangular, tubular through-channel 10 which extends from the front side 6 to the rear side 8 and which has an inlet opening 12 on the front side 6 and an outlet opening 14 on the rear side 8. The inlet opening 12 of the channel 10 is delimited by a plane, front side surface 16 which extends around the opening and which merges with the channel 10 via a curved circumferential transition surface 18, which is also evident from Figure 2. The channel 10 is furthermore designed with a circumferential shoulder 20 which is situated in the central portion of the channel, slightly offset toward its outlet opening 14, and it has a conical portion 22 extending from the shoulder to the outlet opening. The apparatus furthermore has a conventional punch member 24 which is coupled to the frame 4 and which consists of a die 26 whose front side is situated in line with the front side 6 of the frame 4, and one part of which consists of an upper part of the frame 4, and a punch tool 30 which executes a reciprocating motion and is driven by a drive apparatus (not shown). The die 26 furthermore has a through-channel 31 which extends from the front side of the die 26 to the rear side of the die and through which the punch tool 30 is arranged to move. The apparatus additionally has a press tool 32 which executes a reciprocating motion through the channel 10 in the frame 4 and which is driven by a drive apparatus (not shown), and an aluminum tape supply (not shown) with a flat aluminum tape 34, of which a section is shown in Figure 1. The press tool 32 has a cross section which is slightly smaller than that of the channel 10 but which otherwise corresponds with said channel 10. The press tool 32 has a front end 33 which is slightly convex to permit a gentle inward pressing. The function of the apparatus and the method for producing an end closure according to the invention will be described hereinbelow. The pipe 2, which has an end portion of substantially rectangular cross section, is introduced into the channel 10 of the frame 4 through the outlet opening on the rear side 8, and is pushed into the channel 10, with the outside of the pipe bearing against the inside of the channel 10, until the end edge of the pipe is located in contact with the circumferential shoulder 20 of the channel 10. The shoulder 20 is in this case slightly wider than the wall thickness of the pipe for the purpose of receiving the side edges of the end closure, in a manner which is described below. The aluminum tape 34 is collected from the aluminum tape supply and is first fed, by means of a feed device (not shown), forward to the punch member where the sheet extends along, and is pressed against, the front side of the die. Thereafter, material sections 36 are punched out from the aluminum tape in a shape corresponding to an I-beam which lies in the transverse direction of the tape, and which is evident from Figure 1, for the purpose of forming an end closure blank 38. It is also evident from Figure 1 that the blank has a substantially rectangular shape with two long sides 40, 42 in the transverse direction of the tape, and two short sides 44, 46 in the longitudinal direction of the tape. The transition portion between the long and short sides of the blank 38 is drawn in to form gentle inwardly curved corners 48. It is also evident from Figure 1 that the blank is connected to the aluminum tape via two material strips 50 located in the middle of the short sides and opposite each other. The aluminum tape is thereafter advanced along the front side 6 of the frame 4 until one of the end closure blanks 38 is situated centrally in front of the inlet opening 12 of the channel 10, with the end closure blank 38 bearing along its long and short sides against the front side surface 16 of the frame 4. The press tool 32 which executes a reciprocating motion then presses the end closure blank 38 into the channel 10 by means of its forwardly directed linear movement and a substantially centered engagement with the end closure blank. The blank 38 is at this point broken off from the aluminum tape 34, and portions of the long and short sides of the blank 38 bear against, and follow, the curved transition surface 18 of the channel until the blank is situated completely inside the channel. The blank is deformed during this process and shaped to give a cup-shaped or box-shaped end closure with two plane long sides 52, two plane short sides 54, and a bottom 56 which is slightly convex. The cup-shaped end closure also has an aperture 58, which is delimited by side edges 60. The end closure is thereby given a cross section corresponding to the cross section of the channel and of the press tool. The shape of the end closure is clearly evident from Figures 3a and b. The end closure is then pushed further forward into the channel 10 until its aperture 58 is situated level with the shoulder 20, the side edges 60 of the end closure snapping past the shoulder 20 so that the side edges bear against the shoulder 20, which is made possible by the fact that the shoulder 20 is wider than the wall thickness of the pipe 2. In this position, the end closure is situated inside the end of the pipe and closes its end aperture, with its own aperture directed outward from the pipe end. The sides of the end closure in this case bear tightly against the inside of the pipe along their respective plane portions, which fact allows the end closure to be connected to the pipe by hard soldering in a vacuum furnace. The press tool is then pulled back out of the channel 10, the end closure remaining in the pipe as a result of engagement between the side edges 60 of the end closure and the shoulder 20. The pipe is then removed from the frame 4 and moved to a downstream production stage or turned around for closing the other end of the pipe. The sequence described above can then be repeated for closing the next pipe end. It will be appreciated that the invention can be performed in a number of ways within the scope of protection defined in the independent patent claims. The pipe end and consequently the end closure need not have a rectangular cross section, and they can instead have, for example, a circular or oval cross section. The punching operation need not be carried out in conjunction with the pressing operation, and instead can be carried out separately. The end closure blanks can be punched out completely from the tape and then fed, for example via a magazine, to the frame for pressing them into the channel of the frame.

Claims: An apparatus for producing and inserting an end closure for a pipe (2) which forms part of a heat exchanger, said apparatus comprising: a frame (4) which has a first side (6) and a second side (8) situated opposite the first side, and a tubular channel (10) for an end portion of said pipe, said channel running from the first side to the second side and having an opening (12) on said first side which is delimited by a side surface (16) extending around the opening (12); a press tool (32) and means for causing said press tool (32) to execute a reciprocal motion through the channel (10) from said first side (6) of the frame (4); the press tool (32) being arranged, by virtue of its forwardly directed movement, to press an end closure blank (38) into said opening (12) of the channel (10), and to form a cup-shaped end closure by engagement between the end closure blank and said side surface of the frame, and thereafter to push the cup-shaped end closure into the channel (10) and into a pipe (2), which in use, introduced into said channel (10) from said second side (8), with the aperture of the end closure being directed outward from the pipe end, whereby the end closure fits into the pipe end. The apparatus as claimed in claim 1, wherein the channel (10) has an inner circumferential shoulder (20). The apparatus as claimed in claim 1 or 2, wherein the press tool (32) has a convex front end (33). The apparatus as claimed in any one of claims 1 to 3, wherein the side surface (16) merges into the channel via a curved transition surface (18). The apparatus as claimed in any one of claim 1 to 4, wherein the apparatus further comprises a member (26) for cutting metal tape material out from a metal tape (34) in order to form the end closure blank (38). The apparatus as claimed in any one of claims 1 to 5, further comprising a feed device for feeding metal tape (34) along said first side (6) of the frame (4) and across the opening (12) of the channel (10) between the press tool (32) and the frame (4). A method for producing an end closure for a pipe (2) which forms part of a heat exchanger, said method comprising:- introducing said pipe (2) into a tubular channel (10) in a frame (4) which has a first side (6), a second side (8) situated opposite said first side (6), said channel (10) running from said first side to said second side and whose opening (12) on said first side (6) is delimited by a side surface (16) extending around the opening (12), said pipe (2) being introduced until an end of said pipe (2) is disposed within the channel; pressing an end closure blank (38) into the through-channel (10) and pushing the blank (38) through the channel (10), with the blank, by engagement with the side surface (16) of the frame (14) and thereafter with the inner limit surfaces of the channel (10), being shaped to form a cup-shaped end closure having an aperture directed outwardly from the pipe end; and pushing the blank (38) into the end of the pipe (2), whereby said end closure bears against the inside of the pipe. The method as claimed in claim 7, wherein channel has a shoulder (20) located therein, and wherein said introducing step comprises guiding the pipe end into the channel (10) from said second side (8) until the edge of the pipe end bears against the shoulder (20) located inside the channel (10), and wherein the pushing step comprises pushing the cup-shaped end closure through the channel (10) until the aperture of the end closure is situated at least level with the shoulder (20). The method as claimed in claim 8, wherein the shoulder (20) has a width which exceeds the wall thickness of the pipe (2), and wherein the pushing step comprises pushing the end closure is pushed through the channel (10) until its side edges (60) bear against the shoulder (20). The method as claimed in any one of claims 7 to 9, wherein the pressing step is effected by means of a press tool (32) which executes a reciprocal motion. The method as claimed in any one of claim 7 to 10, further comprising cutting said blank from a metal tape (34) by means of a punch member (26). The method as claimed in any one of claims 7 to 11, further comprising cutting the end closure blank (38) from a metal tape (34) such that the blank (38) is connected to the rest of the metal tape (34) by means of thin material strips (50). The method as claimed in claim 14, further comprising feeding the end closure blank (38), together with the metal tape (34), along the first side of the frame (4) and across the opening (12) of the channel (10) for the purpose of being pressed into the channel (10). The method as claimed in claim 15, wherein said pressing step further comprises breaking said blank off from the metal tape (34).

Inventors: DAHL ERIK, DAHL, ERIK
Applicants: VALEO ENGINE COOLING AB
Application year: 1995
Main classification: B21D53
IPC codes: B21D53, F28D1