US2897872A

US2897872A - Methods and apparatus for bending tubes

Info

Publication number: US2897872A
Application number: US591132A
Authority: US
Inventors: Huet Andre
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-06-13
Filing date: 1956-06-13
Publication date: 1959-08-04
Anticipated expiration: 1976-08-04

Description

Aug. 4, 1959' A. HUET METHODS AND APPARATUS FOR BENDING TUBES Filed June 15. 1956 as arm/1401111000118 Fig. 2

United States Patent METHODS AND APPARATUS FOR BENDING TUBES Andre Huet, Paris, France Application June 13, 1956, Serial No. 591,132

1 Claim. Cl. 153-48) This invention relates to a method of bending tubes considerable time and in addition time is needed to in-' sert the tube in the bending machine; as a result, either by conduction or radiation, the heat distributes itself over the whole periphery of the tube instead of, as is intended, acting on a specific region only.

The present invention provides a method and a device which enable the desired difierential temperatures, to be maintained between the various regions of the tube to ensure perfect bending.

According to the present invention a method of bending a tube wherein the conservation of the differential temperatures to be maintained in the tube subjected to a bending operation involving the generation of difierential temperatures in certain regions of the tube, and more especially of a higher temperature in that region of the tube which will eventually form the inside bend of the elbow, is ensured by the provision, inside the tube in a resilient filling material, such as sand, of means for coolng, for example by moistening, the filling material in that tube region or those tube regions which is or are to be heated to a lower temperature than the remainder of the tube.

The present invention also provides apparatus for the performance of the method of invention which comprises a preferably semi-flexible, perforated tube through which water flows, said perforated tube being inserted in the tube to be bent.

The apparatus may also include a strip of preferably flexible sheet metal so shaped that it can likewise be inserted in the tube to be bent for the purpose of forming a partition between two zones of filling sand.

The present invention will now be described in greater detail, by way of example only, with reference to the accompanying drawing, of which,

Fig. 1 shows a cross-section through a tube in which the filling device of the invention has. been inserted, and

Fig. 2 shows a longitudinal section through the tube region under treatment, lodged in the bending die.

If it is desired to bend, for example, the tube region a, the tube is first filled with sand b and, if desired, the ends of the tube are closed by means of stoppers c 0 (Fig. 2). Thus, when the ends of the tube are not closed by stoppers c and c cooling water can freely escape and, by loosely fitting the stoppers when used, an escape route for the cooled water can be similarly provided. Alternatively, if it is desired to insert the stoppers c and c tightly, these stoppers are conveniently provided with at least one peripheral groove as shown at i and i in Fig. 2.

In performing the afore-mentioned bending method, the tube region AB of the tube a--which eventually becomes the inside bend of the elbow-is heated to a temperature greater than that of the region CD which eventually becomes the outside bend of the elbow.

In the sand b in the lower half of the tube there is inserted a preferably semi-flexible, perforated tube d through which flows a cooling means, such as pressurised water, which moistens the sand b in the region CD. The perforations in the tube d preferably face that wall portion of the tube a which is to remain colder.

To complete the action of the device there may further be inserted in the tube a, as shown in Fig. 1, a preferably flexible strip of sheet metal 2 to separate the sand in region CD from the sand in region AB.

Thus, when the region AB of the tube is heated, the heat is no longer so easily transmitted by conduction or by radiation to the region CD which is shielded oif from the heat by the moist sand.

The tube a is then bent by any known method, for instance as represented in Fig. 2 by means of a die h the bottom of which is curved to match the desired shape of the finished elbow. At the beginning of the bending work the tube rests on the two edges of the die 11, and a punch g is applied to the centre portion of the tube a and exerts pressure in the direction indicated by the arrow F to press the tube into contact, with the bottom 1 in the position represented by the chain-dotted lines; this position corresponds to a first bending stage. This operation is then repeated on successive straight portions of the tube until the tube forms an elbow matching the curved bottom 1 of the die h. The sand, the tube a, and the metal strip e in the state in which it is after these operations, are then withdrawn from the elbow.

Instead of the punch g there may be used a punch extending over the whole length of the tube a and shaped to match the form of the inside bend of the finished elbow.

As a result of the above described arrangement the heat applied is not transmitted during the heating operation by conduction or by radiation to the tube region which is to remain colder. When the tube so prepared is then subjected to the bending operation, the finished elbow is of infinitely superior quality; more especially, the internal cross-sectional area of the elbow is larger. The bending work as such may be carried out in any known manner, either by means of a grooved former or of a die-and-punch set, that is to say by compressing the tube in a die so curved as to produce the desired final shape.

I claim:

In an apparatus for bending a tube while filled with a body of resilient porous material comprising a die and a punch for shaping the tube therebetween to define a convex portion and a concave portion, in combination, a perforated tube receivable in the body of the resilient porous filling material contained in said tube on the side of the axis of said tube adjacent said convex portion, said perforated tube being connectable to a source of water to conduct water in a plurality of streams into direct contact with said filling material, and a flexible plate receivable axially in said tube within said body of filling material and dimensioned to intercept the interior surface of said tube along two axial surface lines to provide a partition therebetween to confine part of said body to filling material adjacent said concave portion and to confine the remainder of said body of filling material ad- Patented Aug. 4, 1959 jacent said convex portion of the tube, the said remainder of said body receiving said perforated tube.

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