US2223015A - Tube-bending machine - Google Patents

Description

1 NOV. 26, 194Q. C "E HATHQRN 2,223,015

TUBE-BENDING MACHINE Filed May 27, 1937 v 2 Sheets-Sheet 2 FIGFZ.

'- Ill H l lililiililiimiiliiilllllllllllIIIIII|HIIII l gfllllll llllllllfl lg Emmi.

INVENTOR CHARLES E. HATHORH;

ATTORNEY I 1sFIq.4.-. 7

Patented Nov. 26, 194% UNITED STATES 2,223,015 TUBE-BENDING MACHINE Charles E. Hathorn, Kenmore, N. Y., assignor to Curtiss-Wright Corporation, a corporation of Delaware Application May 27, 1937, Serial No. 144,995

12 Claims. (Cl. 153-49) This invention relates to tube-bending machines, and is particularly concerned with such improvements as will permit of the bending of large diameter thin-walled tubes without buckling of the tube material.

In the aircraft art, particularly, considerable use is made of relatively large diameter thinwalled tubing of stainless steel, aluminum, or other metals, in connection with exhaust systems,

oil lines, and other parts of the power plant, and it is frequently necessary to provide tubes which are bent on a relatively sharp curve. Little difiiculty is experienced when tubes are to be bent. on a large radius, but when sharp bends are attempted with conventional equipment, the tensile strain on the outer side of the tube, and the compressive strain on the inner side of the tubing, tends to deform the material in such a way as to make the bend unsatisfactory. Particularly, the material at the inside of the bend tends to buckle into waves or ripples, resulting in an unsightly article and one which ofiers greater resistance to fluid flow therethrough than is desirable.

An object of the present invention is to provide means by which sharp bends may be made in tubes to the elimination of corrugations in the resultant bent tube. A further object of the invention is to provide means which may be installed on existing types of tube bending machines to adapt them for short radius bends on thinwalled tubing.

Further objects will become apparent from a reading of the sub-joined specification and claims, together with an examination of the accompanying drawings, in which similar numbers indicate similar parts, and in which:

Fig. 1 is a perspective view of the table of a tube bending machine incorporating the invention;

Fig. 2 is a plan of the work station of a tube bending machine, partly in section, to show the details of the invention;

Fig. 3 is a side elevation of the work table of the machine; and

Fig. 4 is a section on the line 4-4 of Fig. 2. The general elements of the machine pictured are conventional, and include a power rotated work table ID, upon which is mounted a clamp assembly H, within which one end l2 of a tube I3 is tightly held. A central bending arbor, designated in its entirety as I4, is mounted upon the table l0 and the clamping assembly ll holds the tube tangent to the arbor It. A base 15 of the machine carries a reciprocable slide l6, movable toward and away from the arbor it by a hydraulic cylinder assembly H, the slide I6 carrying a support [8 provided with rollers 89 over which a guide 20 is translatable, said guide having a forming die 2! attached thereto for movement with the tube 53 as same is drawn around the arbor it. As shown in Fig. 2, a mandrel 22, provided with an end concentric with the arbor I4, is inserted within the tube to prevent the collapse thereof. The die 2! is formed to embrace substantially half of the circumference of the tube l2, as shown in Fig. 4, and the arbor I4 is likewise formed to embrace substantially half of the tube. Accordingly, when the straight tube is assembled in the machine, and when the table In is rotated, the clamp ll draws the tube around the arbor l4, bending same to the desired extent.

When the arbor is of small diameter, and when it is of solid construction according to conventional practice, corrugations appear in the finished bent tube which are most objectionable.

To overcome this, I provide an arbor H such as that shown in the illustrations, which comprises a plurality of parts, including side plates 23 and 24 bolted to and movable with the table ill, the side plates embracing a sheave- 25 mounted for rotation with respect to the plates 23 and 24. Said sheave, around its periphery, may be formed with herringbone serrations 26, and the inside of the sheave is formed as an internal gear 21. A plurality of planet pinions 28 are journaled in the side plates 23 and 24, and engage the gear 21, a sun gear being mounted concentric with the arbor I4, the sun gear being keyed to the shaft of an electric motor or other suitable power source 29, carried by the plate 23. By the planet gear system indicated, the sheave 25 is rotated relative to the side plates 23 and 24, when the motor 29 is energized.

During the tube bending operation, the side ' plates 23 and 24 rotate with the table l0, but

the sheave 25 rotates at a greater rate of speed so that, during the bending operation, the sheave 25 irons out any incipient corrugations which are likely to form, the action thus obtained being somewhat similar to a spinning operation where the excess metal accumulating on the inner wall of the bend is distributed outwardly around the tube periphery by virtue of the ironing action. In use, the sheave 25 and the tube will be well lubricated so that the ironing operation above indicated will avoid tearing the surface of the tube 52.

It has been found that the corrugations flowin from the ordinary type of bending machine are of more or less herringbone form, that portion of the corrugation which is in the plane of symmetry of the tube lagging behind the lateral portions of the corrugation. Accordingly, then, the herringbone elements 26 of the sheave 25 may be formed in opposite sense to have a greater ironing effect upon the incipient corrugations. Or, alternately, the corrugations of the sheave 25 may be formed straight across the face of the sheave.

It has been found that the corrugations in tially eliminated. The mandrel 22 acts as an abutment against which the sheave operates, and during the bending operation, substantial pressure is maintained upon the guide 2!, which moves with the tube, by the hydraulic mechanism ll.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications and changes.

I claim as my invention:

1. In a tube-bending machine comprising a rotatable work table; a clamp thereon. for engagement with a tube to be bent; a stationary guiding die for the tube; an arbor for forming a bend in the tube comprising side platesrotatable with the table and a sheave embraced by said plates and engageable with a portion of the tube to be bent; and means for rotating said sheave relative to said plates and table.

2. In a tube-bending machine, an arbor comprising a plurality of relatively rotatable elements engageable with a tube to be bent, and means for rotating said elements with respect to each other.

3. In a bending machine, a work table, means to clamp work to be bent to the table, a bending arbor engageable with the work, means to rotate said arbor relative to the table, a bending arm holding the work in engagement with the arbor, and means to rotate said arm and table relative to each other at a speed diiierent from the rotational speed of the arbor relative to the table.

4. In a bending machine, a clamping member for work to be bent, an arbor, means for relatively rotating said arbor and clamping member, a bending arm engaging the work to be bent and adapted to bend the work about the arbor, and means for relatively rotating the bending arm and clamping member about the arbor center but at a speed different from that of the arbor relative to the clamping member.

5. In a bending machine comprising a clamp and reaction member relatively rotatable about a center, means to effect said rotation, an arbor on said center around which work held by said clamp and bearing on said reaction member is adapted to beb'ent, and power means for rotating said arbor at a speed greater than that of said clamp relative to said reaction member.

6. In a bending machine, a work table, means to clamp work to be bent to the table, a bending arbor engageable with the work, means to rotate said arbor relative to the table, a bending arm holding the work in engagement with the arbor, and means to rotate said arm and table relative to each other at a speed different from-the rotational speed of the arbor relative to the table, said means comprising a motor driven epicyclic gear train contained within the arbor for driving said arbor relative to the clamp.

'7. In a tube-bending machine, a work table,

means forrotating the table, a bending arbor for forming a tube to be bent, power means for rotating said arbor with respect to said table and tube during table rotation, said arbor having corrugations across the surface thereof for engagement with the tube for ironing incipient corrugations which might tend to form upon the tube, and reaction members bearing on the surface thereof for engagement with theytube for ironing incipient corrugations which might tend to form upon the tube, and reaction members bearing on the tube on opposite sides of the arbor, one of which members is fixed and the other of which is secured to the table.

9. In a tube-bending machine; a bending arbor comprising an annular member externally circumferentially grooved and provided with gear teeth, side plates carrying said arbor, planet pinions journaled in said side plates engaging said gear teeth, and a sun pinion journaled in the plates drivably engaging said planet pinions; 8. power rotated work table upon which the side plates are rigidly mounted, means for driving said sun pinion whereby the annular member is forced to rotate with respect to a table,

that of the table, and a rotationally fixed member bearing on the tube on the other side of the arbor from that part of the tube secured to the table.

11. In a tube-bending machine, a work table on which a tube to be bent is secured, means for rotating said table, a bending arbor bearing on the tube for forming same and mounted for rotation with respect to said table, said arbor having corrugations across the surface thereof for engagement with the tube and for ironing incipient corrugations which tend to form upon the tube, means for rotating said arbor in the same direction as the work table and at a greater speed than the speed of the work table, and a substantially flxed reaction member bearing on the tube on the other side thereof from the.

Images