US2650636A

US2650636A - Apparatus for bending tubing

Info

Publication number: US2650636A
Application number: US294787A
Authority: US
Inventors: Jr Harry C Jennings
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-06-21
Filing date: 1952-06-21
Publication date: 1953-09-01
Anticipated expiration: 1970-09-01

Description

Sept. 1 1953 Filed June 21, 1952 H. 0. JENNINGS, JR 2,650,636

APPARATUS FOR BENDING TUBING 2 Sheets-Sheet 1 llllllglillll llllwlllllllqlllw HQQEV c: JfA/N/A/GZS, ue

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Sept. 1, 1953- H. c. JENNINGS, JR

APPARATUS FOR BENDINQ TUBING 2 Sheets-Sheet 2 Filed June 21, 1952 INVENTOR.

w 5 W N f a y E W H Mam Patented Sept. 1, 1953 UNITED STATfiS PATENT OFFICE APPARATUS FOR BENDING TUBING Harry G. Jennings, J12, Los Angeles, Calif.

Application June 21, 1952, Serial No. 294,787

1 Claim. 1

This invention relates to an apparatus for bending tubing.

In the construction of wheel chairs, certain types of porch furniture, and similar articles, the frame is formed of sections of seamless metal tubing. This tubing is frequently bent to provide elements of the frame. For example, a leg of a wheel chair may have its upper end bent at approximately right angles thereto to provide an armrest. There are a number of other situations where it is desirable or necessary to bend the tubing at various angles, frequently at right angles.

When ordinary cylindrical tubing, such as is used in wheel chairs, porch furniture and the like, is bent severely the outer side of the tubing is stretched and the inner side of the tubing is greatly compressed even though the tubing is bent around the end of a mandrel that is inserted therein. The compression on the inner side of the tubing is such as to produce a plurality of transversely extending wrinkles or corrugations. These corrugation-s produce a roughened surface on the inner side of the bend: which is objectionable for a number of reasons including that of unsightliness.

An object of the present invention is to provide an apparatus for bending tubing wherein the wall of the tubing at'the inner side of the bend is longitudinally indented in the course of the bending operation. By indenting the tubing Wall in this manner the objectionable transverse corrugations are avoided and in lieu thereof a relatively short narrow longitudinal indentation is formed at the inner side of the bend which is normally in a position so that it is concealed or not readily observable.

With the foregoing and other objects in view, which will be made manifest in the followin detailed description and specifically pointed out in the appended claim, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Figure l. is a top plan view of a portion of a bending apparatus embodying the present invention, parts being broken away and shown in horizontal section and illustrating a section of tubing as having been mounted thereon preparatory to being bent;

Fig. 2 is a view similar to Fig. 1 but illustrating the bend as having been completed;

Fig. 3 is a horizontal section taken substantially upon the line 33 upon Fig. 2;

Fig. 4 is a view similar to Fig. 2 but illustrating the tubing as being in the process of being bent;

Fig. 5 is a horizontal section taken substantially upon the line 55 upon Fig. 4 in the direction indicated; and

Fig. 6 is a perspective view of a portion of bent tubing which has been bent in accordance with the present invention.

Referring to the accompanying drawings wherein similar reference characters designate similar parts throughout, the major portion of the bending apparatus disclosed conforms to one form of tubing bending apparatus that is now in genera1 use. Consequently all details thereof have not been illustrated. Essentially the apparatus disclosed consists of a mandrel Iii on which a section of seamless metal tubing T is adapted to be telescoped. This mandrel is usually mounted on a limber rod. arranged axiallyoi its end which holds the mandrel against longitudinal or axial displacement but enables lateral movement to some extent.

On one side of the mandrel there is swingably mounted a jaw H which is semi-cylindrically recessed, as at 12, to accommodate approximately one-half of the cylindrical tubing. This jaw is swingably mounted for swinging movement about a pivot provided by a vertical shaft I3. This pivot may be forcibly rotated either by power or manually. Attached to the jaw H is a semicircular roll it which has a groove l5 extending around its semi-circular periphery and centrally of this groove there is an outwardly projecting rib It. The end of the mandrel is rounded off, as indicated at H, and that portion of the mandrel which is adjacent its end and which is opposite the rib H5 is longitudinally grooved as indicated at IS. A movable jaw 19 is mounted on the jaw l l and is adapted to be tightened toward the jaw H by means of a manually operated eccentric 20 so that that portion of the tubing which projects beyond the end of the mandrel I0 may be clamped between the two jaws I9 and I l and swung thereby about the pivot It. In so doing the tubing is axially shifted and bent, the bendin action taking place about the roundedoff end ll which is concentrically arranged with respect to the pivot It. On the opposite side of the mandrel Hi from the roll It there is a movable support El adapted to be advanced and retracted by means of a manually operated linkage 22. This support has rollers 23 and slidably supports against the rollers a follow block 2 1. The follow block 26 is grooved to accommodate approximately one-half of the tubing T. When it is desired to bend the tubing the tubing is telescoped onto the mandrel and the jaw 19 tightened toward the jaw II. The support 2| is also advanced so that it crowds the tubin and the mandrel toward the roll I4. The jaw I I, movable jaw l8 and roll 14 are then swung as a unitary structure about the axis of the vertical shaft [3, thus bending the tubing around the rounded end I! of the mandrel. As this bending takes place the follow block 24 rolls against the rollers '23 and moves with the tubing from the position shown in Fig. 1, through the position shown in Fig. 4, to the position shown in Fig. 2. As the bending takes place the rib I6 indents or depresses the tubing wall at the inside of the bend into the groove [8 thu producing on the inside of the bend a short narrow indentation indicated at 25 on Fig. 6. As will be noted from an inspection of the drawing, if the roll employed is to bend the tubing through a ninety degree bend, the rib l6 occupies an arc of less than ninety degrees of the roll. The ends of the rib are beveled 01f, as indicated at 26 and 27, to be tangent to the bottom or back of the groove I 5. These beveled portions on the rib enable the tubing to be slipped onto the mandrel, in Fig. 1, without interfering with the rib and after the bending is complete the bevel at 21 is disposed opposite the mandrel, enabling the tubing to be slid off of the mandrel when the bend is completed. In other words, in both extreme positions the rib I6 is disposed wholly outside of the groove 18. But in the intermediate position, shown in Fig. 4, the rib I6 enters the groove I8 producing the depression at 25. This depression extends only along the inside of the bend in the tubing and usually it will be located on the under side of a structural element of a wheel chair, porch furniture or the like. Consequently it is not readily observed. The indenting of the tubing wall at this point enables the bend to be made Without the formation of transverse creases or corrugations such as are formed when the tubing is bent without employing the rib 16 or the groove l8. Consequently in side elevation tubing bent in this manner appears to have a smooth continuous bend.

The conventional tube bending apparatus may be readily modified to adapt the present invention by merely grooving the end of the mandrel with a groove l8 and providing a semicircular roll M on which a rib I6 is formed. Usually in the construction of these rolls two half rolls are held in assembled relation and are turned on a lathe so as to form the groove and a continuous rib l6. Thereafter the bevels at 26 and 21 may be formed by grinding off the ends of the rib so that these bevels will be disposed opposite the mandrel at both extreme positions of the roll.

From the above described construction it will be appreciated that a novel method and apparatus is provided for bending tubing wherein by the formation of a narrow longitudinal indentation in the tubing wall at the inside of the bend a smooth bend can be secured, avoiding the formation of transverse corrugations.

Various changes may be made in the details of the construction without departing from the spirit and scope of the invention as defined by the appended claim.

I claim:

A tube bending apparatus comprising a man drel on which tubing to be bent may be telescoped, a roll rotatably mounted adjacent the end of the mandrel, the end of the mandrel being rounded off with a radius of curvature approximately concentric'with the axis of rotation of the roll, means for clamping the tubing against the roll, means for swinging the clamping means and roll about the axis of rotation of the roll, a follow block mounted for movement longitudinally of the mandrel on the opposite side thereof from the roll, there being a circumferentially extending rib extending partially around the roll, the ends of the rib being beveled off approximately tangent to the roll, and there being a groove formed in the mandrel opposite the roll and extending to the rounded end of the mandrel whereby as the roll and clamping means are swung the rib will depress the tubing into the groove over a portion of the interior of the bend in the tubing and the tubing may thereafter be removed from the mandrel by sliding it longitudinally off of the end of the mandrel.

HARRY C. JENNINGS, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,285,275 Harder June 2, 1942 2,357,873 Bower Sept. 12, 1944 FOREIGN PATENTS Number Country Date 271,815 Great Britain July 21, 1927