US2882953A - Tube bender having a support sleeve with a circular aperture merging into an oval aperture - Google Patents

Description

Ap'z'fi 21, 1959 A. HUET 2,882,953 TUBE BENDER HAVING A SUPPORT SLEEVE WITH A CIRC APERTURE MERGING INTQ AN OVAL APERTURE Filed Oct. 6. 1954 ULAR fl/VDRE #067 INVENTOR.

United States Patent TUBE BENDER HAVING A SUPPORT SLEEVE WITH A CIRCULAR APERTURE MERGING INTO AN OVAL APERTURE Andre Huet, Paris, France, assi'gnor to Combustion Engineering, Inc., New York, N.Y., a corporation of Delaware The present invention relates to tube bending and particularly to an improved apparatus for making return bends in metallic tubes.

In bending a straight tube it is conventional to draw the tube on a rotating bending wheel, in the groove of which the tube is received. In the apparatus of this type, the tube is applied against the bending wheel and held in position by two retainer wheels.

In his earlier patent, No. 2,689,596, applicant proposed in order to facilitate the bending of tubes, especially over a narrow radius of bending, to heat the tube before bending, especially in the portion which will become the crotch portion of the bend.

In the case of thin wall tubes (i. e. tubes whose wall thickness is less than of the diameter of the tube) and more especially in the case where it is necessary to heat the tube, it can happen that the retainer wheels, crushing the low-resistance metal, will cause a buckling, i.e. a flattening of the tube cross-section and wrinkles which spoil the attainment of a perfect bend.

To remedy this inconvenience, the applicant has devised a tube-support apparatus, consisting of a sleeve, preferably in two parts each having two complementary pieces, completely surrounding the tube in advance of its insertion on the bending wheel, and guiding it almost up to the point at which the tube begins to assume its curvature on the bending wheel. This support sleeve is fixed to the bench carrying the bending wheel and its presence, in addition to assuring delivery of the tube without flattening or wrinkling, to the bending wheel, permits elimination of one of the retainer wheels.

Moreover, in the case of dealing with tubes where, for a certain length, the cross section is previously ovalized to facilitate bending, the support sleeve must have an oval cross section groove corresponding to that of the tube, but it is provided that there be at the entrance of the support sleeve and over a certain length, a groove of a cross section such that it can serve as well for passage of the ovalized tube as for the same tube still having its cylindrical cross section. In this way the part of the tube that remains cylindrical can enter the sup port sleeve during the end of the bending operation, and it is only necessary to ovalize the length of straight tube which has to be bent.

The support sleeve can even be such that it will produce ovalization of a tube as the latter passes through it under the efiect of traction exerted by the bending wheel.

In the drawings:

Figure 1 is a plan view of the tube matrix or support placed on the bending apparatus ahead of the bending in accordance with the invention;

Figure 2 is a larger scale section on the line 2-2 of Fig. 1.

Figure 3 is a larger scale section on the line 3-3 of Fig. 1.

As can be seen in Figure 1, a tube a that is to be bent is engaged by a rotating bending wheel 10 having a groove of usual shape, in which the tube is held by a single retention wheel 12. A device for gripping a tube in accordance with the invention is shown in Figure 1. It comprises a drawing unit which can be composed of finger 14 mounted on the bending or shaping wheel 10. The finger 14 is formed with an aperture that receives and surrounds the tube. The part of finger 14 at the base of this aperture which bears on the outside of tube a may have teeth which bite on this part of the tube. A bracket 16 fixed to the finger 14 supports a jaw 18 pivoting on bracket 16 whose end penetrates to the interior of tube a to apply itself on the inner wall of the tube. The end of jaw 18 may also have indentations or teeth which bear against and grip on the internal wall of tube a.

Gripping of the tube a between fingers 14 and jaw 18 is accomplished under the efiect of the push exerted by a jack 20 mouted on the bracket 16. The jack acts via links on the end of pivoted jaw 18 on the one hand and on a fixed point on bracket 16 on the other hand. This gripping means is more fully described in my co-pending application, Serial No. 460,590 filed October 6, 1954.

According to the invention, before engaging the bending wheel, tube a is supported by a guide, preferably in two complementary pieces 22, 24 (Figs. 1 and 2), between which there is a groove whose cross section corresponds to that of the tube to be treated; part of the tube a can be ovalized beforehand as shown in Figs. 1 and 2. Piece 22 is fastened to the bench on which the Wheel 10 turns, and the second part 24 of the matrix engages in part 22 as shown in Fig. 2. It also can be fastened to the bench.

A heating device 26 is located between the groove of the rotating bending wheel 10 and the adjacent end of the support matrix 22, 24 as seen in Fig. l, in such a way as to assure during the bending the continuous heating of the part of the tube which will form the crotch of the bend, this occurring immediately before thee tube takes its curve on the bending wheel 10. After this the tube is cooled again, for example by contact with the grooves of the wheels 10, 12 which can have an interior cooling circulation of a sort that the tube, once it has assumed its curve, will regain its rigidity when cold.

-In the case of a thin walled tube, the cylindrical cross section tube may previously to bending be ovalized over a length (AB) corresponding to the length of the bend to be formed (as seen in Figs. 1 and 2). The long axis (EF) of the oval is in the plane of symmetry perpendicular to the axis (X) of the bending wheel.

As it is preferable only to ovalize beforehand the length (AB) of tube a corresponding in general to the length of the tube to be bent, it is necessary to arrange, at the end of the bending movement, that a certain portion of the tube a that has remained cylindrical, can penetrate into the support matrix 22, 24 without passing over the bending wheel. This is why, according to the invention, the support matrix is in two parts. The part of the matrix 22, 24 located closest to the wheel 10 has an aperture of oval section and the outer part 32, 34 of the said matrix aperture has a section such that (as seen in Fig. 3) it may serve at the same time for the passage of the oval section of the tube (indicated in outline by dot-dashes G) and the part of the tube that is still cylindrical (shown in dotted outline H).

The aperture inside the support sleeve 22, 24 can moreover be such that it changes gradually from a cylindrical to an oval shape, in such a way that the actual ovalization of part of the tube takes place in the said supporting matrix 22, 24 under the force of traction exerted on the tube by the wheel 10.

It goes without saying that modifications in details of construction in the invention may be made without thus deviating from its scope.

- WltaLI claim is:

In apparatus for bending a cylindrical tube having a,

portion of ovalized section followed by a portion of normal circular section of a zdiameter slightly greater than that- .of the short axis of the ovalized section, which apparatus has .aibending wheel provided with a, groove for receiving the ovalized section of the tube, the improve ment comprising; a tube support and guide sleeve positioned immediately forward of thelocation in which the tube first assumes curvature on the bending wheel and formed with an aperture of ovalized section, corresponding to that of the tube, in a location adjacent the bending wheel and merging into an aperture, more remotely located from the bending wheel, which has a cross-section corresponding on one axis to the major axis of the ovalized section of the tube and on an axis normal thereto corresponding to the said circular sectionof the tube.

References Cited inithe file of this patent UNITED STATES PATENTS 434,804 Quiggin Aug. 19, 1890 1,135,875 Brinkman Apr. 13, 1915 1,924,734 Brown Aug. 29, 1933 1,967,487 Waisner July 24, 1934 2,229,462 Kurtz Jan. 21, 1941 2,267,774 Wall -Dec. 30, 1941 FOREIGN PATENTS 494,207 Canada July 7, 1953

Images