A process for making a multiple duct distributor is known from US 4,580, 324.

US 4,580, 324 describes a method for rounding a flat-oval tubing where a male arbor is inserted into one end of the tube conforming the tubing to a round cross section. The male arbor cuts up the webs of the tubing making a tubing with a round single port inlet and a flat multiple port outlet. During the presented process, the collapsing of the partition walls is a consequence of the process. The tubes are therefore limited to the use of interconnecting one circular tube and one multiport tube.

Since the forming of the connector is done by arranging a processing tool on one of the ends of a tube, the variation of the cross section will be limited by the original cross section of the tubes. This limits the extent of deformation possible for the work piece without getting cracks in the partition walls and surrounding walls.

It is an object of the invention to present a forming process which enables the cross section of a multiport tube to be altered while the partition walls dividing the ports inside the tube is maintained unbroken. It is further an object of the invention to present a method for forming multiport tubes enabling a higher rate of deformation.

It is furthermore an object of the invention to present a distributor enabling a plurality of tubes to be connected to one circular tube. It is also an object of the invention to present a distributor which leads a fluid from a tube, through the distributor and out through a plurality of outlets while ensuring the same flow through all the outlets.

The process according to the invention gives a possibility to form a multiport distributor having a varying cross section where the inner walls stay intact. In the process a die is surrounding a first end portion, contracting the cross section of the end portion. A mandrel is introduced into the second end portion of the work piece, expanding the cross section of the second end portion. The extent of deformation in the first and second end portions can be decreased due to the combined process of contraction and expansion.

The process for making a distributor and a distributor made by the process will now be described by figures where fig. 1 a-e shows the cross sections of a first embodiment of a work piece formed according to the invention, where fig. 1 a shows the cross sections of a collapsed end portion of the first embodiment of the work piece, fig. 1 b shows the cross section of central portion of the first embodiment of the work piece, fig. 1 c shows the first cross section of an intermediate portion of a gradually expanded wall of the first embodiment of the work piece, fig. 1 d shows the second cross section of an intermediate portion of the gradually expanded wall of the first embodiment of the work piece, fig. 1 e shows the cross section of an end portion of the expanded part of the first embodiment of the work piece.

Fig. 2 shows a side view of a distributor made from a work piece according to fig. 1.

Fig. 3 a-d shows the cross sections of a second embodiment of a work piece formed according to the invention, where fig. 3 a shows the cross section of a collapsed end portion of the second embodiment of the work piece, fig. 3 b shows the cross section of a central portion of the second embodiment of the work piece, fig. 3 c shows the cross section of an intermediate portion of a gradually expanded wall of the second embodiment of the work piece, fig. 3 d shows the cross section of an end portion of the expanded part of the second embodiment of the work piece, fig. 4 shows a side view of a distributor made from a work piece according to fig. 3.

Fig. 1 a-e shows the forming of a work piece 1 into a distributor starting from a cross section as shown on Fig. 1 b. The work piece 1 is extruded having a circular outer wall 3 and corrugated inner walls 2.

A mandrel (not shown) having a plurality of bars is introduced into the work piece 1. Each bar of the mandrel is controlling the area of one duct 5. The ducts 5 are formed in the open space defined by the outer wall 3 and the inner walls 2. The cross section areas of the ducts are equal, but may differ in shape.

The cross section of a first end portion, a, of the work piece is reduced by compressing a die onto the outer surface. The reducing of the cross section of the inner walls 2 is controlled by the interaction of the bar surfaces of the mandrel controlling one duct each, while the outer die (not shown) ensures a uniform outer wall 3 of the work piece. The mandrel will be forming the corrugated inner walls 2 into flat inner walls which will be thicker than the originally corrugated inner walls.

Towards the second end portion, e, the work piece is expanded according to the steps shown in fig. 1 c, 1 d and 1 e. The mandrel used for the forming operation in the first embodiment has four bars. Each bar is lead into one respective duct 5 of the work piece 1.

The intermediate portion of the work piece 1 where the cross section is expanded, will after the expanding process have a gradually increasing cross section.

The first intermediate portion having a gradually increasing cross section has a rectangular shape as illustrated on fig. 1 c. Due to the low degree of deformation, the inner walls 2 will to some extent still be corrugated. Towards the end portion, e, where the degree of deformation is increasing, the inner walls 2 will straighten out. In order to expand out to the shape forming the end portion, e, the wall material is stretched. The end shape of the work piece will lead the inner wall thickness to be considerably thinner at the expanded end portion than the original work piece inner walls.

Due to the combination of compression and expansion of said end sections, the overall deformation of any part of the work piece is kept below any possibility for cracking.

Due to the corrugated shape, the inner walls 2 defining the multiple ducts 5 keep their main shape mostly unchanged through the first expansion process. An outer part of the

work piece 1 is further expanded into a rectangular shape. The inner walls 2 are straightened out, retaining the multiple ducts 5 intact through the work piece. The work piece is thereby processed to a cross section varying from a round tube with thicker inner walls to a rectangular tube having thinner inner walls.

Fig. 2 shows a side view of a distributor made from a work piece according to fig. 1. A tube of circular cross section can be connected onto the round end portion, a, of the distributor. The total inner cross sectional area of all the ducts 5 of the distributor is substantially the same as the inner cross sectional area of the tube being connected to it.

Each of the ducts will mutually have the same cross sectional area to ensure the same flow of the fluid into all the ducts 5 of the connector. In this way, substantially the same flow rate will be ensured out of all the ducts 5 at the outlet of the distributor and into the tubes being connected into each duct at the outlet.

Fig. 3 a-d shows a second embodiment of a work piece 1'being expanded according to the method. The work piece is extruded having a circular outer wall 3, and inner walls 2' dividing the internal cross section of the work piece into seven ducts 5'with one central duct 5'surrounded by six external ducts 5'all having the same cross sectional area, see fig.

3 b.

A first end portion, a', of the work piece 1'is contracted maintaining a straight circular outer wall 3'and the original inner structure of the work piece 1'. The cross section of the first end portion is reduced by introducing a mandrel having a plurality of bars (not shown) into the work piece, thereafter surrounding the work piece by a die (not shown) and compressing the die onto the work piece.

The die ensures a uniform outer wall 3'having a straight round shape. Each inner bar of the not shown mandrel is controlling the inner area of one respective duct 5'. The reducing of the cross section of the ducts 5'is controlled by the interactions of the bars controlling the inner cross section of one duct each, and the die which will force the outer wall 3'to maintain a predefined shape.

Towards the expanded end portion, d', the work piece is expanded into the shape as shown on fig. 3 c and 3 d. The mandrel (not shown) used for the shaping operation of the second

embodiment has seven bars. Each bar is entered into one respective duct 5'. The intermediate portion of the distributor where the cross section is expanded, will after the expanding process have a gradually increasing cross section.

The inner part of the work piece 1'as seen on fig. 3 c will have outer ducts 5'gradually gaining a circular cross section thereby giving a dented outer surface 3'of the work piece 1'. On fig. 3 d all the ducts 5'has a completely circular cross section enabling one tube of a corresponding cross section to be connected into each of the ducts 5'.

Fig. 4 shows a side view of the distributor according to fig. 3. The circular end, a', of the distributor can be connected into a tube of circular cross section. The total area of the seven inner cross sections of the ducts in the distributor is the same as the area of the cross section of the tube being connected.

All the openings of the distributor have identical areas in order to ensure the same amount of flow into all the ducts of the connector, thereby getting the same flow out of all the ducts at the outlet of the distributor and further into the tubes or hoses being mounted on the outlet of the connector. The distributor hereby makes it possible to control the flow in each of the multiple ducts and further into a plurality of tubes.

By the combining of reducing the cross section of a portion of the work piece and expanding the cross section of an other portion of the work piece, a flexible production method is obtained which enables a higher degree of deformation of the initial work piece.

It should be understood that other embodiments of the distributor can be made within the scope of the invention.