US1936765A - Method of bending and apparatus therefor - Google Patents

Description

JNVENToR Filed April 4, 195o J F LAWSON METHOD OF BENDING AND APPARATUS THEREFOR Nov. 28, 1933.

Patented Ney'. 2S,

. fvwm@ elm, Flfc ,A YFT* W UN Si ill/ PATENT il O it 3338565 FETHE) @F AND APPARATUS Jenn it". Lawson, Ereohlyn, N. Y., assigner te Steel and Tubes, Ene., a eerporatien ci? @hilo applicaties .anni s, isst. Ns. cerner 6 Claims.

This invention relates to bending pipe, tubn ing, solid bars, wire and the like; more particu-- lai-ly to bending such articles to straight; and still more particularly to straightening lengths oi such articles which, without abrupt bends anywhere, depart somewhat as a whole from a right line. rlhe invention includes both a method and an apparatus.

The invention is intended for metal pipe and tubin.Cr especially, but is applicable also to bars, wire and other articles of the saine general kind, as above indicated. For brevity, the terms articles and elongated articles" are employed hereinaiter to indicate all articles oi this lrind.

According to the method of the invention, each and every short length, and preferably each and every iniinitesimally short length, bi the article to be treated, is bent systematically in substantially or quite every direction, one of the bends (it may be the first one, so iar as final result is concerned) being made, preferably, at least on such a short radius that the elastic limit oi the metal is exceeded (so that the length would have a permanent set were nothing further done with it) and the remaining bends being made on radii of various greater lengths, usually of successively greater lengths, until the iinal desired form, say the straight, is reached. From another aspeet, the method of the invention consists of bending each short or elemental length of article or article wall spirally, as itmay be called, in the` manner hereinafter described. l

Basically the apparatus of the invention may consist or any piece, structure or apparatus providing an elongated smoothly-curving curved guideway or path of various lengths of radii of curvature, the shortest of which exceeds, at least preferably, the elastic limit of the article to be treated, and which path terminates and blends into, say, a straight exit portion, through which the elongated article can be passed while being rotated, and which piece or structure constrains the article against local bending except on such radii as are prescribed by the method of the lnvention. Preferably mechanism for pushing the elongated articles through the guideway or path is provided at the entrance end of the piece, structure or apparatus, and another mechanism to pull the article through the guideway or path is provided at the exit end of the guide-way providing piece, structure or apparatus, these mechanlsms also serving to rotate the article in passing.

These and other features of the invention appear in the accompanying drawing and the following description of the matters there illustrated.

in this drawing, Fig. l is a plan view, partly in section, ci? a machine embodying the invention. Fig. 2 is an end elevation, partly in section, of the article-pushing mechanism, and also 0i' the article-pulling mechanism, oi Fig. l. Fig. 60 3 is a side elevation o one of those mechanisms. Fig. i is an illustrative diagram referred to hereinafter.

While the method or the invention is not limitd ed to any particular apparatus, this method may be understood from the apparatus illustrated in the drawing which I have devised for carrying it out. The elongated curved guideway or path for the article is outlined by a metal helix l', the turns of which are placed substantially as close together as possible. internally, the diam= eter of the helix is only a little greater than the external diameter of the article, say A 17, to be treated. Such a hellxis a preferred device for outlining the guideway or path, since it bears t5 on the article at many closely-spaced points and thus is well adapted to prevent bending or the article anywhere on a radius other than the re4 spective local radius of curvature of the guideway. To hold the helix in the desired shape for the path, the helix may rest against a base plate 2, b e provided at its sides with two exible plates 3 placed at right angles to the base-plate 2, and. be held down to the baseplate by a cover plate d placed parallel with the baseplate 2. The two plates 2' and i may be permanently placed with respect to each other. Preferably however the side plates 3 are held between a series of thread ed bolts `5, 6, 7, 8, 9, 10 and l1, which are. provided in such numbers as may be necessary to confine wthese plates and the helix to the desired curved path and which may be mounted in bracl= ets l2 permanently fastened between the lower and upper plates 2 and fl; by means of the bolts the curvature of the path may be adjusted from time to time, for example to suit the particular metal of the articles used with it. To set up the machine for say the length of tubing l'l, I first take a short piece of this tubing or a piece of j similar tubing made from the same metal, and lull) by bending theplece on successively shorter radii of curvature, I 'lnd the radius or curvature, or, say, about the longest radius of curvature, which, when the tubing is bent on it, gives the piece a permanent set. That is to say, I first find a radius of curvature, and usually about the longest radius of curvature,'whlch exceeds the elastic limit of the article to be treated. I then so set the threaded bolts, say 5 and 6, as to curve this end of the lhelix 1 to this radius which exllo `stantially tangentially into, its straight portion l through, as may be found by trial. The direc- ;with reference to Fig. 4 differs from the opera- '.whole these parts are stationary and the tube 17 vthis short length is treated as held against ro- .bending of the short length and the effect on it.

by the relative sharpness of the angle 18, 19, 20.

2 masones ceeds the elastic limit of the article 17. It being This is the first or a preliminary step in the opdesired to straighten this tube 17 for example, erations. vNext, one end of the length or elethat is to say, the tube being somewhat bent it ment, say the end 18-19, is moved about, relabeing desired to straighten it accurately, the tive to the other end 19-20, in the manner illusthreaded bolts at the opposite end of the helix, say trated in the diagrammatic figure; that is to say, 10 and 11, are so set as to bring the axis of relative to 20 the end 18 is forced to travel along this portion of the helix 11 into a straight or a spiral, as from point 18 to point 22,` to 23, to 24, right line for at least a short distance. The inand so on until the finish point 37 is reached, the termediate bolts, say 7, 8 and 9, are then so adlatter being, in the present instance, the center justed as to cause the axis of the helix to folof the spiral, and in the center line of the part low a smooth curve from the entrance end of 19-20 extended representing that the element short radius of curvature to, and to blend sub- 18-19-20, at the conclusion of the operations on it, is straight. Each and every infinitesimally short length of the tube being bent in exactly the same manner, it is evident that the tube as a whole will have a uniform lengthwise shape at the iinish of the operation. In effect, every infinitesimally short length of tube passed through the device of Fig. 1 is bent in this manner and this systematic bending is the preferred method of the invention.

The mechanisms illustrated at the lower left of Fig. l and outlined at the upper right, are mechanisms for pushing and pulling the articles through the guideway or path 1, and simultaneously rotating them. The description of one will serve as a description of the other also, the two beingalike. In flxed spaced brackets 43 and 44 are -journaled two annular. heads 45 and 46 which, in conjunction with the parallel bars 47, 48, 49.and 50 Joining the heads, constitute a rotating frame. The external periphery of head 46 is toothed for driving by a gear 51 on shaft 52, which may be driven, for example, by an electric motor 53 directly, or through an extension of the shaft and universal Joints 54' in the manner of lthe puller mechanism at the upper right of Fig. 1. The bars 47 and 48 carry a pair of belt sprockets 55 and likewise the bars 49 and 50 carry a pair of belt sprockets 58; each pair of sprockets carries a chain belt 57 or 58 to which are attached article (tube) grippers 59 suitably recessed to grab the article, e. g. the tube 17. An internal gear 63 is fixed to one of the brackets. Shafts 64 and 65 carried by the frame heads 45 and 46, are provided with gears 67 and 68 respectively, meshing with internal gear 63 for driving thereby as the frame is rotated; through their miter gears 69 and 70 and the miter gears 71 and 72 on shafts of sprockets 55 and 56 these 125 shafts 64 and 65 drive the sprockets 55 and 56 and thereby the belts 57. It will be observed therefore that the motor 53 will rotate the frames of the tube pushing mechanism (at the lower left of Fig. 1) and the tube pulling mechanism (at the upper right) and thereby the tube, and simultaneously, the motor driving in the proper direction, ywill rotate the sprockets 55 and 56 in the various directions indicated'by the arrows on the sprockets and thereby cause the two mechanisms to simultaneously push and pull the tube through the guideway in the direction indicated by the arrow adjacent the tube.

It will be understood however that ,the invention is not limited to the details illustrated and 140 dlescribed, except as appears hereinafter in the c aims.

in ,other words, I so adjust the intermediate bolts that the radii of curvature of the curved portion of the helix axis increase gradually and successively from the bolts 5 or 6 to about the bolts 11, or perhaps to a point somewhat farther back toward the bolts 10, and at this point cause the helix axis to blend tangentially into its straight part. Preferably the curve of the curved portion of the path is a parabola. To straighten then say the tubes 17. it is only necessary to force the tube through the path of guideway provided by thehelix 1 and simultaneously rotate the tube a suitable number of times as it passes tion of rotation, that` is to say whether clockwise or counter-clock-wise, isimmaterial; however it seems to be somewhat easier to force a tube 17 through the pathway when rotating' it in a direction contrary to the screw-thread-efiect provided by the turns ofO the helix. The path may be lubricated as desired or found necessary.

It will be observed that passing a' tube 17 through such a path while rotating the tube, causes each and every infinitesirnally` short length or element of the tube to be bent repeatedly and systematically in every direction, the bend near the entrance, near the bolts 5, being made on such a short radius of curvature that the'elastic limit of the metal is exceeded, and the remaining bends being made on radii of successively greater lengths until the straight portion of the path is reached near its exit. Fig. 4 represents diagrammatically the treatment `which each and every such short length undergoes in passingthrough such a guideway as 1 while being rotated. In one respectV the operation described tion described with reference to Fig. 1. Ilhat is to say, in Fig. 41 the guideway or path-providing parts mounted on the base plate 2 neither rotate as a whole nor move longitudinally, but as a is moved through the guideway and at the same time is rotated within it; in Fig. 4, to the contrary, in which only an inflnitesimally short length (18-19--20) of a whole tube is shown,

tation and longitudinal movement while, as it were, the guideway is assumed to be passed over this short length of tube and at the same time rotated about this short length. The actual is the same in both cases. Assuming (what is probably not the fact) that the bend-A ing of each element is concentrated at one I claim:

point 19 in it, then the line 18, 19, 20 may be 1. Apparatus for bending elongated'articles,4 taken as representing an inilnitesimally ab@ comprising means providing an elongated curved length or longitudinal element of the wall of the rpath for the article and bearing on the article at tube, while occupying, say, a position about oppo' such closely spaced points thereon as to confine site the bolts 5. The' element is here bent on a the article to such smoothly-curving path without short radius of curvature, as represented in Fig. 4 permitting local bending of the article on a radius materially shorter than the respective local raassess@ l dius of curvature of the path, the radius ci curvature of said path at one point exceeding the elastic limit of the article and the radii of curvature of said curved path at one side of said point being of greater lengths and of lengths successively greater than each other, and mechanism for pushing an elongated article through said means, in the direction of from said point of radius exceeding the elastic limit to the portion of the cui ve of longer radii, and for simultaneously rotating the article within said means.

2. Apparatus for bending elongated articles, comprising means providing an elongated curved path for the article and bearing on the article at such closely spaced points thereon as to confine the article to such smoothly-curving path without permitting local bending of the article on a radius materially shorter than the respective local radius of curvature of the path, the radius o! curvature of said path. at one point exceeding the elastic limit of the article and the radii of curvature of said curved path a't one side of said point being of greater lengths and of lengths successively greater than each other, and mechanism for pulling an elongated article through said means, in the direction of from said point o! radius exceeding the elastic limit to the portion of the curve of longer radii, and for simultaneously rotating the article within said means.

3. Apparatus for bending elongated articles, comprising means providing an elongated curved path for the article and bearing on the article at such closely spaced points thereon as to corinne the article to such smoothly-curving path without permitting local bending of the article on a article.

radius materially shorter than the respective local radius oi curvature (1f/the path, the radius of curvature oi said path at one point exceeding the elastic limit of the article and the radii of curvature of said curved path at one side oi'. said point being of greater lengths and of lengths succcssively greater than each other, and mechanism for pulling and mechanism for pushing an elongated article through said means, in the direction of from said point of radius exceeding the elastic limit to the portion of the curve of longer radii, and for simultaneously rotating the article within said means.

4. The method of treating articles oi the kind described for the purposes described, which consists in bending each short length of the article on a radius exceeding the elastic limit of the article and thereafter repeatedly bending the same short length of the article in various directions to successively lesser degrees. 5. The method of straightening an elongated article, which consists in bending each substantially-lnnitesimally short length of the article on a. radius exceeding the elastic limit of the article and thereafter repeatedly bending the same in various directions to successively lesser -degrees until the vstraight condition is reached.

6. Apparatus for bending elongated articles, comprising means for conning the article to a substantially parabolic path and means for causing relative rotational and longitudinal movement between said confining means and the elongated JOHN F. LAWSON.

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