US3109477A

US3109477A - Mandrel for pipe bending machines

Info

Publication number: US3109477A
Application number: US226093A
Authority: US
Inventors: Trent W Avera; Joseph A Cuuningham
Original assignee: CROSE UNITED CORP
Current assignee: CROSE UNITED CORP
Priority date: 1962-09-25
Filing date: 1962-09-25
Publication date: 1963-11-05
Anticipated expiration: 1980-11-05
Also published as: DE1527278B2; GB1026884A; DE1527278A1; DE1527278C3

Description

Nov. 5, 1963 T, w. AVERA ETAL MANDREL Foa PIPE BENDING MACHINES 3 Sheets-Sheet 1 Filed Sept. 25. 1962 INVENTORS. Tre/yf /44 7L/am y. l f l /624 U 2f f 5% I M., N w

wrbi M T. w. AVERA ETAL. 3,109,477

MANDREL FOR PIPE BENDING MACHINES s sheets-sheet 2 mm m.

Nov. 5, 1963 Filed Sept. 25, 1962 //wf/ /y//////// Nov. 5, 1963 T. w. AVERA ETAL MANDREL FOR PIPE BENDING MACHINES 5 Sheets-Sheet 3% Filed Sept. 25, 1962 United States Patent Oiiice 3,109,477 MANDREL FUR PEPE BENDENG MACHINES Trent W. Aver-a and Joseph A. Cunningham, Tulsa, Okla., assignors to Curse-United Corporation, Tulsa, Okla., a corporation of ltlahoma Fiied Sept. 25, 1962, Ser. No. 226,693 16 Ciaims. (Cl. 153-63) This invention relates to the art of bending pipe and more particularly to pipe bending apparatus in the Irature of a mandrel adapted for expansion inside a pipe to be bent in tight engagement with the inner surface of the pipe for the purpose of supporting the latter for bending and adapted to eX with the pipe during the bending operation so as to maintain it smooth and cylindrical at the zone of bend.

It is the primary object of the present invention to provide a mandrel which may be quickly expanded against the pipe and held tightly therewithin during the bending operation and thereupon rapidly contracted so that the pipe may be advanced for successive bending operations Without loss of time, to the end that the complete bending operation may be completed without slow-down inteiference because of the use of the mandrel in conjunction with the pipe bending machine.

The most important object of the instant invention is to provide an expansible mandrel that yis fully effective in its function of maintaining the pipe smooth and cylindrical at the zone of bend throughout a wide range of diftering types of pipe insofar as diameter is concerned and including pipes Whose walls differ in thickness, as well as tensile strength and hardness of the material that makes up the wall of the pipe.

Another important object of the present invention is the provision of a collapsible pipe bending mandrel that is provided with parts which properly engage the pipe Wherever Iit has any tendency whatsoever to buckle, Wrinkle, collapse, or otherwise deform improperly as a consequence of the bending operation so that the inner surface of the pipe throughout the zone of bend remains or becomes smooth and uninterrupted as well as uniformly cylindrical throughout the length of the bend.

Still another important object of the instant invention is the provision of a mandrel in the nature of an elon gated flexible body that is substantially cylindrical throughout its length or otherwise has the same cross sectional shape of the pipe to be bent and made in a manner to yield or bend properly with the pipe as the latter is being bent, 4while at the same time maintaining its tight grip against the pipe throughout the length of the body, with the result that the necessary attenuation takes place in the pipe along the large radius of the bend and the essential compression takes place in the pipe throughout the smaller radius of the bend while the pipeengaging parts of the mandrel remain in tight contact therewith.

A further oject of the present invention is to provide a. mandrel whose pipe-engaging parts bear against the pipe in a manner to avoid any possible bulging of the pipe at various location-s Within the bend so that bumps, depressions and other undesirable deformities are completely avoided.

An extremely important aim of our instant invention is to provide apparatus for facilitating the bending of pipe that operates in a manner to assure supporting engagement of the mandrel parts with the pipe quickly and easily and in complete absence of interference, slow-down or ineffective clamping as might otherwise be experienced if a frictional, sliding interengagement between the mandrel and the pipe were necessary during the expansion and contracting operation.

Yet another aim of our instant invention is to provide 31,109,477 Patented Nov. 5, 1963 a mandrel wherein the forces exerted against the pipe are properly distributed, not only longitudinally, but circurnferentially of the mandrel.

lt is contemplated that the instant invention shall have the important aim of providing a pipe bending mandrel which combines a `powerful and truly radial action of expansion with not only the over-all flexible characteristics of the mandrel, but the resilient nature of the pipeengaging parts, all for the purpose of attaining the necessary and desired results above enumerated.

In the drawings:

FIGURE 1 is an end elevational view of a mandrel for pipe bending machines made according to our present invention;

FIG. 2 is a side elevational View of the mandrelshoW- ing the same in a contracted position Within a fragment of a pipe, the latter of which is in turn illustrated schematically within certain parts of a pipe bending machine;

FIG. 3 is an enlarged cross-sectional view taken on line 3 3 of FIG. 2, illustrating only the mandrel, but in an expanded condition;

FIG. 4 is a crosssectional view fragmentarily illustrating one of the expansion units or assemblies, the section being within a plane through and parallel to the longitudinal axis of the mandrel;

FIG. 5 is an enlarged, detailed end-elevational View of one of the lbeams of the uppermost pipe support of the mandrel;

F'I'G. 6 is an enlarged, detailed, cross-sectional View through one of the pipe-engaging parts of one of the beams of the lower pipe support of the mandrel;

FIG. 7 is a cross-sectional View taken on line 7-7 of FIG. 6;

FIG. 8 is an enlarged elevational view of the drive entirely removed from the remaining structure of the malldrel showing that side of the drive opposite to that seen in FIG. 2; and

FIG. 9 is essentially a top view of the drive partially in section and taken along irregular line 9-9 in FIG. 8.

As best seen in FIG. 2 of the drawings, our expansible pipe bending mandrel which embodies the concepts of the instant invention is in the nature of an elongated flexible body broadly designated by the numeral 10 and provided with spider-like framework 12 and 14 at its ends. Body 10 includes a plurality of longitudinally spaced expansion units or assemblies 16, `18 and 20 which may be of identical construction; therefore, reference may be had to FIGS. 3 and 4 of the drawings for an understanding of the details of the unit 18.

A housing 22 has a ring 24 closed on opposite faces thereof by a plate 26 and a hollow cone 28, the latter of which has a cylinder 30 attached thereto.

A piston 32 within the cylinder 30 has its stern 34 attached to a disc 36, the latter of Which is in turn provided with a guide 38 reciprocably carried by the plate 26.

The ring 24 carries a plurality of radially reciprocable rams or plungers 40 that are actuated by links 42 which pivotally interconnect the plungers 404 with the disc 36. It is to be understood at this juncture that the details of construction of the fluid-actuated plungers 46 as just above described may be varied within the spirit of the instant invention since the construction thereof, as depicted in FIGS. 3 and 4 `of the drawings, is for illustrative purposes only, showing but one manner of power actuation for the plungers 40. Within these concepts, therefore, it is manifest also that means other than `the pneumatic or hydraulic actuated piston 32 may be provided to supply the power to force the plungers 40 in a radial direction outwardly from the axes of the

units

16, 18 and 20 that is coincident with the reciprocable path of travel of the piston 32, the stem 34, the disc 36 and the guide 3,8.

Each of the plungers 40 of each of the

units

16, 18 and 20, regardless of the number of plungers 40 chosen for each unit, and regardless of the number of expansion unitsl that are utilized in the mandrel, may be provided with a shoe in the nature of a pad or a block, positioned to rmly engage the inner surface of pipe 44 when the mandrel is expanded in the manner illustrated by FIG. 3 of the drawings. Such expansion takes place upon movement of the pistons 32 to the inner ends of fthe cylinders 30, placing the links 42 in substantial alignment with the plungers 40. The plnngers 40 are then in substantial surrounding alignment with the disc 36 and are effectively locked against inward movement so that there is no need to rely substantially on fluid pressure as the means for preventing inward radial movement on the part of the plungers 40 as the result ofthe pressures which they must withstand during bending of the pipe 44.

All of the shoes of the mandrel which engage the pipe 44 as aforementioned may be resilient if desired but, as illustrated, there are three types of

shoes

46, 48 and Si), the shoes 46 Iand 48 all being resilient. The shoes 50 may be solid, made, for example, from a suitable metallic, hard rubber or plastic material. The rubber or other substance chosen for the shoes 46 and 4S should be se-v lected in light of the great pressures to be applied thereto and if resilient material is also selected for the shoes 50,v it is contempla-ted that such rubber or other material be appreciably harder and much less resilient than the material chosen for the shoes 46 and V48. In other words, by way of example, shoes may be identical if so desired.

AllV of

rthe shoes

46, 48 and 5G are provided with a single central opening 52 which receives the head of a cap screw 54 extending into the outermost end of the corresponding plunger 40 through spacers 56. Each of the

shoes

46 and 48 has a metallic pusher plate 58 bonded to its innermost face and interposed between the corresponding head of bolt 5.4 and spacer 56. On the other hand, it is desirable, when the shoes 50 are made from metallic material, that their outer faces be provided with a facing `6l) bolted` or otherwise attached thereto, and made from beliting or suitable material capable of protecting theinner surface of pipe.44 or protective coatings that are oftentimes provided on the inner face of pipes 44. It may be, however, that facings 60 can be eliminated, depending on the natu-re of the material chosen for blocks 50.

` 'It is seen, therefore, that each of the

assemblies

16, 18 and 2(3.is provided with a continuous annular row of shoes or pads concentric to their axes (which is coincident with the longitudinal axis of the body such shoes being in side-by-side relationship and spaced only slightly when expanded, as shown in FIG. 3 of the drawings.

i vIn addition, the body 10 isprovided with a number of arcuate rows 62, `64, 66 and 68 of shoes 46, also concentric with the longitudinal axis of the body 10 and disposed at the top of the latter. The row 62 is interposed between fthe annular rows 70 Vand 72, whereas the rows 64, 66 and 68 are in side-by-side relationship between the two annular rows 72 and 74.

Similarly,a row 76 of `shoes 50 is interposed between

rows

70 and 72 and a number of

rows

76, 78, 80 and 82 Y Vof shoes 50 are disposed in side-by-side relationship between the rows 72 and 74. The

rows

76, 78, 80 and 82 are likewise concentric with the longitudinal axis of body 10 at the bottom of the latter.

-lt should be explained at this juncture that each of the

annular rows

70, 72 and 74 Vis made up of an arcuate row or segment ofshoes 46 in longitudinal alignment with proximal shoes .46 of the rows 62, 64, 66 and 68. In much the same manner, each of Ithe

rows

70, 72 and 74 includes an 4arcuate row or segment of shoes 50 disposed in longitudinal alignment with proximal shoes 50 of

rows

76, 78, 80 and 82. This means, then, that the segmental lillV in covering relationship to the slots 163.

4

4arcuate rows

62, 64, 66, 68, 76, 78, 80 and 82 do not have any shoes corresponding to the shoes 4S that are found in the

annular rows

70, 72 and 74. VThe shoes 48 are located in the

rows

70, 72 and 74 between their up-V permost shoes 46 and their lowermost shoes Si), the disposition of shoes 48 being such as to move laterally in opposite directions against the pipe, as distinguished from a general up-and-down movement on the part of shoes 46 and Sil at the top and bottom of the pipe 44.

The arrangement is such as to present an uppermost pipe support assembly broadly designated by the numeral 84 and a lowermost pipe support assembly broadly designated by the numeral S6. The upper support 84 includes a plurality of elongated,

flexible beams

88 and 90 of substantially identical nature, except only that the beams 88 'extend the full length of body 10, whereas the beams 90 are somewhat shorter. Each of the

beams

88 and 90 includes a longitudinal series or straight row of shoes 46 in end-to-end relationship clamped together as a unit.

It is to be understood at this juncture that each of such straight rows could comprise a single length of resilient material rather than be subdivided into individual shoes as shown. A plurality of elongated, longitudinally extending, flexible strips, preferably of metallic material 92, are provided for each beam 8S and in the same manner each beam 90 has a number of similar strips 94. Each beam S8 is also provided with support `structure in the nature of a strip 96 throughout its length and a similar strip 98 is provided for each of the beams 90. Grooves 1li() extending longitudinally of the body 10 are provided in the outermost faces of each of the shoes 46 for receiving the strips 92 and, as `seen in FIG. 3, the strips 94 are similarly recessed within the outer faces of the shoes 46 of the beams 90.

The

strips

96 and 3 are in the nature of bars substantially wider and somewhat heavier than the

strips

92 and 94 and extend along the inner faces of the shoes 46 of corresponding beams 88 and 99. The clamping means for connecting the shoes 46 of the beams 88 and 9i) together as indivi-dual units is in the nature of a bolt `for each strip y92 |and 94, respectively, such bolts 102 passing through

bars

96 and 9? as best seen in FIGS, 2 and 5, loc-ated at each Vend respectively of each beam `88 and 90'. lt is now clear that, inasmuch as the shoes 46 are clamped together between

strips

92 and 96 and between strips 94 and 93 in straight rows extending longitudinally of the body 16, the shoes'46 of segmental rows 62, 64, 66 and 68 move in unison with the shoes 46 of

annular rows

70, 72

and 74 as the

units

16, 18 and Ztl are in turn expanded and contracted in unison.

tlf desired, still another beam'three blocks long might be provided beneath each of the four block beams 90.

The shoes Sil that make up the longitudinally extending beams 164 of the lower support 86 are Vinterconnected by longitudinally extending strips or bars 106 that bear against the inner faces of the shoes 50, it being noted in FIG. 7 that the bars 166 are provided with elongated slots 168 that extend longitudinally of the body 10 for clearing the bolts 54, and each of the spacers 56 that Iare proximal to such enlarged openings 16S has an external flange or enlargement 116 that bears against the bars 106 It is also desirable, as noted in FIG. 3, that each of the

bars

96 and 98 be provided with a clearance opening 112 for bolts 54 that is slightly enlarged :to present at least a slight looseness of the corresponding bolts `54 within the openings BecauseA of theV bars 166 for each of the beams 1,04, all of theshoes Sil of the arcuate or segmental rows 76, 78, Sil and 82 move in unison with the shoes 5l)y of the Y

annular rows

70, 72 Vand 74 in much the same manner as above described with respect to the beams .S3 and 90 of the upper support 84.

It has been found desirable to malte .the beams 164 longer than the beams 68; hence, still another arcuate row of shoes 50 is provided on the bars 106 adjacent the row 70, such additional row being designated by the numeral 114 and disposed to place the row 70 between the rows 76 and L114.

The shoes 48 may be identical with the shoes 46, except only that they are not interconnected by flexible strips and accordingly are ydevoid of the grooves lili). They presen-t, therefore, secondary pipe-engaging means and cooperate with the two primary supports 84- and 86 in producing the desired results obtained through use of the mandrel of the instant invention.

While the

strips

92 and 96 clamp together all of the shoes 46 of the

rows

70, 62, 72, 64, 66, 68 and 74, the

strips

94 and 98 of the beams 90 connect together only the shoes 46 of the

rows

78, 62, 72 and 64. On the other hand, each strip 106 of each beam 184 interconnects all of the shoes 5G of the

rows

114, 78, 76, 72, 78, 80, 82 and 74.

It is now evident from FIGS. 2 and 3 that when the body 16 is fully expanded the inner face of pipe 44 is engaged by all of the

shoes

46, 48 and 58, as well as by all of the

strips

92 and 94, the engagement by the shoes 50 being through their facings 60. The engagement is continuous longitudinally of the body at the

supports

84 and 86 and is continuous circumferentially at the rows 7d, 72 and '74, inasmuch as the sets of shoes 46., 48 and 50 of each of these annular rows present continuous pipeengaging bands for the mandrel body 10. It is also believed readily apparent that the shoes between the outer strips and the inner bars serve as spacers for maintaining the outer pipe-engaging strips properly spaced from the support bars therefor.

It is to be explained at this juncture that the arrangements above described may be varied considerably within the concepts of the instant invention to suit the desires of the manufacturer and the needs of particular pipe bending operations. The supports 84 and 86 extending longitudinally of the body 1t) and generally continuous throughout its length have been provided in such manner because of the fact that the greatest amount of adequate support for the pipe 44 is needed at the small and large radii of the bend.

On the other hand, there is a lesser need for supporting the pipe 44 between the upper and

lower supports

84 and 86, making it possible to attain good results without need for continuing either the support 84 or the support 86 throughout the circumference of the body 10, thereby reducing the cost of manufacture and the over-all weight of the mandrel, as well as simplifying its construction. It is also contemplated that the number of rows of continuous shoes, as well as the number of

units

16, 18 and 2d and the spacing therebetween may be varied considerably from that illustrated in the drawings and above explained, depending upon various pipe bending requirements.

Framework 12 is attached to the unit 16 by brackets 119 and similar brackets 312i) mount the framework 14 on the unit 2o. The primary support for the body 10 in the pipe 44 when body 16 is contracted, as illustrated in FIG. 2, is through a pair of inclined wheels 116 on each of the frameworks 12 and 14, respectiveiy, each wheel 116 being provided with suitable toe-in and toe-out, as well `as height adjustment means 118 for preventing the mandrel from rolling over in the pipe 44.

Fore and aft movement of the mandrel is provided by the drive, illustrated in FIGS, 2, 8 and 9. A plate 122 on the framework 14 carries a jackshaft 124 which in turn swiugably supports an extension 126 having a friction roller 128 adjacent its lowermost end.

A prime mover such as a fluid motor 1311 carried by plate 122 is operably connected with the shaft 124 by chain and sprocket wheel means 132 and another chain and sprocket wheel means 134 operably interconnects shaft 124 Vand roller means `128.

Power means which may take 4the form of a liuid piston and cylinder assembly 136 pivotally interconnects extension 126 with an upstanding arm 138 on framework 14.

The roller 128 rests loosely on the bottom of the pipe 44 during pipe bending operations while the body 1t) is expanded, but when relative movement between the mandrel and the pipe 44 is to take place the assembly 136 is actuated to compress roller 128` tightly against the pipe 44, without lifting the mandrel off the guide wheels 116, to provide a friction or traction drive. Thereupon roller 128 is rotated by actuation of the prime mover 138. The pipe 44 is advanced from left to right, viewing FIG. 2, after each bending operation; therefore, roller 128 is caused :to rotate .in a direction to maintain the mandrel in substantially the position shown in FG. 2 with respect to the pipe bending machine during the advancement of the pipe 44.

Pipe bending machines are conventionally provided with a transversely arcuate support 140 for the pipe 44 together with a transversely concave but longitudinally convex bending shoe 142 in diametrically opposed relationship to the support 140x Therefore, as successive bends are made in the pipe 44 it is normally advanced several inches after each bending operation, whereas the mandrel itself is maintained in the same relationship to the support 140 and the shoe .142 by operation of the driving mechanism.

The mandrel is controlled from a remote point exteriorly of the pipe 44, the controls extending into the pipe 44 `for operable connection with fluid control valving mounted on framework 1l2. The valve that controls the ldownward motion of the drive roller 128 may be the same valve that controls the expansion and contraction of the ma-ndrel. When the mandrel is contracted, the assembly 136 may be actuated by the same fluid that retracts the three expanding mechanisms of the mandrel. When the mandrel is expanded, fluid in the cylinder of assembly 136 may be exhausted to atmosphere through the valve. The uid control valving for operating the prime mover 130 should also be adapted for actuation exteriorly yof the pipe 44 remote from the mandrel It is lnow apparent that when the body 10 is expanded so that all parts of its periphery are tightly engaged with the pipe `44, the latter is firmly and adequately supported for bending and, since the various pipe-engaging parts are strategically located, rather sharp bends may be easily and quickly lformed without any collapsing or other deformations taking place at any point within the Zone of the bend. lMore panticularly, as bending takes place, all of the iflexible shoes 46 and 48 yield with the bend and at the same time all of the

strips

92, 94, `96, 98 and 106 iiex longitudinally to accommodate not only the small radius `of the bend adjacent the shoe 142 but the larger radius along the support `140.

Manifestly, the bending operation necessitates tensioning of the material from which the pipe 44 is made at the shoe 142, but no buckling or wrinkling: occurs because of the support that is provided by the beams 88 and of the support 84. These supports, made as illustrated `and above described, eliminate all corrugations that would otherwise form at the shoe .142 and the

beams

88 and 90 perform such ifunction in a manner to also prevent fonmation of dents, bumps, depressions and other undesirable deformities.

By the same token, the support 86 permits the necessary attenuation of the material forming the pipe 44 at the larger radius 'of the bend and does so in a manner to avoid formation of irregularities of any nature whatsoever in the pipe 44.

All such results take place while the mandrel effectively for-mspipe 44 into a `cylindrical shape yor holds i-t cylindrical while bending takes place. Such result occurs by the cooperative action of the shoes 48, since the continuous

annular bands

70, 72 and 74 prevent the pipe 44 from taking on an elliptical or other undesirable crosssectional configuration.

As the large radius of `the bend is lformed along a support 140 the flexible bars 106' are permitted to bend therewith While the shoes 50 maintain their tight grip with the pipe -44 because of the loose t incorporated in the support 86 by the slots 108. Similar results are obtained during flexing of .the

strips

92, 94, 96 and 98` to accommodate for the smaller radius of the bend because of the loose t provided atthe openings 112.

lrIt is to be understood, however, that the entir-e body 10 remains in .full and rrn contact with the interior of the pipe {44 during the bending operation while the two radii of the bend Vare formed, since it is not possible for any of the plungers to retract once the discs 36 become `substantially aligned with the plunger, as above explained.

It is for this reason that the body '10 maintains the same cross-sectional configuration as the pipe 44 throughout the length of the body 10' and throughout each bending operation. lt is therefore impossible for the bending operation to cause the pipe 44 to take on any cross-sectional configuration other than cylindrical, and it is also not possible for any irregularity such as Wrinkling and depression to be yformed in the pipe 44.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

l. An elongated, longitudinally flexible and resilient, transversely expansible mandrel adapted yfor insertion into a pipe to be bent for supporting the pipe against distortion adjacent the zone of bending thereof, said mandrel comprising:

a first, elongated, longitudinally flexible and resilient assembly for supportingily engaging a longitudinal `area of the pipe -adjacent said Zone during bending of the pipe;

`a second, elongated assembly disposed in spaced, op-

posed, generally aligned, parallel relationship to said rst assembly and provided with elongated support structure extending longitudinally of the second assembly;

elongated, yresiliently flexible, pipe-engaging strip means disposed outwardly of the support structure in generally parallel, spaced relationship there-from;

resilient spacer means disposed between said strip means and the supportstructure along the longitudinal length thereof; Y

a pair of expansion units spaced apart longitudinally of `the assemblies and each operably coupled to said Ione assembly and to the support structure of the other assembly at longitudinally spaced, directly opposed points thereon; and

means connecting theV strip means and spacer means with said support structure, whereby upon movement of said assemblies relatively away Ifrom each other by said units, said yone assembly and the strip means are shifted into firm, substantially conforming, supporting. engagement with opposed, longitudinally extending areas Iof the pipe at said zone thereof.

2. An elongated, longitudinally iiexible and resilient, transversely expansible mandrel adapted for insertion into a pipe to be bent for supporting the pipe against distortion adjacent the zone of bending thereof, said mandrel comprising:

`a rst, elongated, longitudinally flexible and resilient assembly for supportingly engaging a longitudinal Varea of the pipe adjacent said zone `during bending of the pipe; l y

a second, elongated assembly disposed in spaced, opposed, generally aligned, parallel relationship to said` first assembly andV provided with elongated, longitudinally iiexible and resilient support structure Vextending longitudinally ofthe second assembly;

elongated, resiliently flexible, pipe-engagingrstrip means disposed outwardly of the support structure in generally parallel, spaced relationship therefrom;

` spacer means disposed between said strip means and the support structure along the longitudinal length thereof;

a pair of expansion units spaced apart longitudinally of the assemblies and each operably coupled to said one assembly and to the support structure of the other assembly at longitudinally spaced,- directly opposed points thereon; and

means connecting the strip means and spacer means with said support structure, whereby upon movement of said assemblies relatively away from each other by said units, said one assembly and the strip means are shifted into firm, substantially conforming, supporting engagement with opposed, longitudinally extending areas of the pipe at said zone thereof.

`3. An elongated, longitudinally flexible, transversely expansible mandrel adapted -for insertion into a pipe to be bent for supporting the pipe against distortion adja-` cent the Zone of bending thereof, said mandrel com-` prising:

ia pair of generally circular, normally substantially axially aligned, spaced, independent expansion units each having a series of radially movable, circumferentially projecting members thereon;

upper and lower elongated, spaced, opposed, aligned,

l generally parallel, :pipe-engaging Vassemblies each having a plurality of parallel, elongated, iongitudinally resiliently iexible beams carried by members of the units in aligned relationship longitudinally of the assemblies, movable radially with respective members Vand serving to interconnect the units with the members thereof normally lying in imaginary, generally parallel, spaced circles, said assemblies having outer faces of transverse configuration substantially conforming to the transverse inner surface configuration of the pipe and adapted to support opposed upper and low-er areas of the pipe at said zone during bending of the pipe, said Ibeams of the upper assembly each having at least one elongated, resiliently flexible, pipe-engaging strip thereon and each beam supporting its strip for flexing separately from the flexing of a respective beam; and

operating means coupled to said membersof the units for simultaneously shifting all of the members along the radial paths of travel thereof whereby the beams of said assemblies may be radially shifted to move the strips and the beams of said lower assembly into Ifirm, conforming engagement with said opposed upper and lower areas of the pipe.

4. A mandrel as set forth inv claim 3 wherein said operating means includes pneumatically operable components permitting rapid shifting of the members toward respective extremities of the radial paths of travel thereof.

5. In a pipe bending mandrel having an elongated body adapted for insertion into a pipe to -be bent, said body comprising:

a Vpair of diametricaliy opposed pipe supports, each yhaving at least one beam provided with ay row of separate pipe-engaging shoes and a continuous, longitudinally extending, elongated element;

a pair of longitudinally spaced expansion assemblies disposed between the supports for moving the latter radially outwardly in diametrically opposite directions; Y

means connecting the elements with the assemblies for outward movement ofthe elements by the assemblies;

and Y means coupling each rowV with its corresponding element for normally holding the shoes in a straight line i extending longitudinally of the body and for outward movement of each row of shoesV as a unit `by its element, said elements being flexible for longitudinal deformation of the beams in response to the bending of the pipe into arcs conforming to the curvatures of the bend in the pipe while the shoes are held against the pipe by said assemblies.

6. In a pipe bending mandrel having an elongated body adapted for insertion into a pipe to be bent, said body comprising:

a pair of diametrically opposed, pipe-engaging supports,

one of the supports having a plurality of side-byside, parallel beams, each beam being provided with l a continuous, longitudinally extending, elongated bar, a plurality of continuous, longitudinally extending, elongated, parallel strips spaced radially outwardly from the bar, and a row of separate shoes between the strips and the bar;

a pair of longitudinally spaced expansion assemblies disposed between the supports and each provided with a plurality of radially reciprocable rams;

means connecting each bar with one ram or" each assemlbly respectively for outward radial movement of the lbars by the rams; and

means connecting the strips with corresponding bars for clamping the shoes in place and normally holding the same in straight lines extending longitudinally of the body and for outward movement of each row as a Unit by its bar, said bars, said strips and the other of said supports all being flexible for longitudinal deformation of 4the beams and the other support in response to the bending of the pipe into arcs conforming to the curvatures of the bend in the pipe while the supports are held against the pipe by said assemblies.

7. A collapsible mandrel adapted for expansion inside la pipe to support the latter for bending and for flexing with the pipe during bending, said mandrel comprising:

a pair of spaced expansion units, each having an anfnular row of shoes, and each having mechanism for moving its yshoes radially outwardly against the inner face .of the pipe;

structure interconnecting the units; and

exible means for preventing wrinkling of the pipe durling bending, said means sp-anning .the distance between the units and being disposed for movement against the pipe by the mechanisms as the shoes are moved outwardly.

8. A collapsible mandrel adapted for expansion inside a pipe to support the latter for bending and for flexing with the pipe during bending, said mandrel comprising:

ya ilexible body of uniform diameter throughout its length, said body including a plurality of annular rows of shoes;

a series of strips of resilient material extending longitudinally of the body, said strips connecting the shoes of each row with the shoes of adjacent rows; and

means for exerting radial thrust on :the shoes for forcing the shoes and the strips against the pipe.

9. A collapsible mandrel adapted `for expansion inside a pipe to support -the latter for bending and for llexin-g with the pipe during bending, said mandrel comprising:

an elongated, llexible body of uniform. diameter throughout its length, said body including a plurality of sideby-side, longitudinally extending, ilexible beams, each of said beams having a longitudinally row of adjacent pipe-engaging blocks and a resilient, pipe-engaging strip extending longitudinally of the body, together with means attaching the strip to the blocks, at least certain of the blocks of each beam having means coupled therewith for reciprocating the beams radially of the body, said blocks being disposed to engage a substantial tarea of said pipe longitudinally thereof to provide support for the area during bending of the the pipe at s-aid area.

10. For use in bending pipe, a mandrel for maintaining the pipe smooth and cylindrical `at the zone of bend,

while liexing with the latter therewithin during bending, said -mandrel including:

an elongated body having an upper and a lower longitudinal, transversely arcuate, series of -side-by-side as- 5 semblies, each of said assemblies being provided with an arcuate row of pipe-engaging blocks normally concentric to the longitudinal axis of the body, said blocks being disposed to engage a substantial portion of the upper :and lower areas of the pipe;

flexible pipe-engaging elements extend-ing longitudinally of the body and connected to said assemblies; and a pair of -units supporting the blocks for radial movement of the latter .and lsaid elements into and out of engagement with the pipe, said units being spaced longitudinally of the body whereby the body exes between the units yduring bending of the pipe. 1l. For use in bending pipe, a mandrel for maintaining the pipe smooth and cylindrical at the zone of bend, while flexing with the latter therewithin during bending, said mandrel including:

an elongated, generally cylindrical body having a succession of side-by-side, transversely arcuate, circumferentially extending rows of resilient, pipe-engaging blocks throughout its length in substantially concentric relationship to the longitudinal axis of the body;

means connected with each block of la spaced pair of said rows -ior shifting the same radially into tightly clamped engagement with the pipe, said blocks being disposed to engage a substantial area of the pipe; and

exible pipe-engaging means connecting the remaining rows With said pair of rows for movement therewith into and out of engagement with the pipe, whereby said remaining rows yield to the bending of the pipe in response to deforming of said ilexible means as said pair of rows remain clamped tightly to the pipe.

l2. For use in bending pipe, a mandrel for maintaining the pipe smooth and cylindrical at the Zone of bend, while flexing with the latter therewithin during bending, said mandrel including:

an elongated body having an arcuate series of longitudinally extending, ilexible, pipe-engaging strips, together with spaced annular rows of pipe-engaging blocks, with said series and said rows in substantially concentric relationship to the longitudinal axis of the body;

means connecting each strip with one block of each row; and

means vfor each row respectively .and circumscribed thereby for moving the blocks and strips radially 011twardly into engagement with lthe pipe.

13. For use in bending pipe, a mandrel for maintaining vthe pipe smooth and cylindrical at the zone of bend, while iiexing with the latter therewithin during bending, said mandrel including: p

an elongated body having an arcuate series of longitudinally extending, ilexible pipe-engaging strips, together with spaced annular rows of pipe-engaging blocks, with said series :and said rows in substantially concentric relationship to the longitudinal axis of the body;

means connecting each strip with one block of each row;

means Ifor each row respectively and circumscribed thereby for moving the blocks `and strips radially outwardly into engagement with the pipe; land means disposed in diametrically opposed relationship to said series and connecting said rows for limiting the extent of movement of the latter toward and away from each other.

14. A mandrel adapted for insertion into a pipe to be bent and comprising: l

a substantially cylindrical body having a pair of longitudinally extending, diametrically opposed, transversely arcuate pipe supports, each having a number of rows of side-by-side, pipe-engaging blocks, one

Y 11 support having a plurality of flexible pipe-engaging strips mounted on the blocks thereof; and 'structure between the supports for moving the same radially outwardly in opposite directions until the blocks and strips engage the pipe.

15. In pipe-bending apparatus for insertion into a pipe which is to be bent, an expansible mandrel having the same cross-sectional shape as the pipe to be bent and including: f

a pair kof spaced expansion units each having a series of spaced rams reciprocable simultaneously toward and away from the pipe and each having a Vrow of pipe-engaging pads surrounding the same with each pad secured to the outermost end of a corresponding ram .for reciprocation therewith, presenting a continuous band when the unit is contracted, with the pads disposed in side-by-side relationship; and

exible means bridging the units and connected therewith for engagement with the pipe when the units are expanded.

16. In apparatus of the kind described:

an elongated mandrel having the same cross-sectional varea of a pipe into which the same is to be inserted during bending of the latter, said mandrel including:

a plurality of side-by-side, arcuate rows of pads having outermost pipe-engaging faces,

said rows being concentric with the longitudinal axis of the mandrel `and extending throughout the length of the latter,

certain of said rows being continuous and annular in surrounding relationship to said axis,

the remaining rows being interposed between the continuous rows, certain of the pads being resilient and disposed to present a number of straight, longitudinal, side-by-side series of end-to-end pads at the top of the mandrel, certain of the pads being disposed to present a number of straight, longitudinal, side-by-side series of end-to-end pads at the bottom of the mandrel, each of said series of pads having a flexible bar extending longitudinally of the mandrel along the inner faces of the pads thereof,

. each pad of each series at the bottom of the mandrel being connected with the corresponding bar,

i' each of said series of pads at the top of the mandrel References Cited in the file of this patent UNITED STATES PATENTS 2,323,039 Hill June 29, 1943 2,339,543 Bishop Jan. 18, 1944 2,380,344 Sutton 2 July 10, 1945 2,906,226 Myrick et al Sept. 29, 1959 3,043,361 Kelso -...1 v l a July 10, 1962

Claims

1. AN ELONGATED, LONGITUDINALLY FLEXIBLE AND RESILIENT, TRANSVERSELY EXPANSIBLE MANDREL ADAPTED FOR INSERTION INTO A PIPE TO BE BENT FOR SUPPORTING THE PIPE AGAINST DISTORTION ADJACENT THE ZONE OF BENDING THEREOF, SAID MANDREL COMPRISING: A FIRST, ELONGATED, LONGITUDINALLY FLEXIBLE AND RESILIENT ASSEMBLY FOR SUPPORTINGLY ENGAGING A LONGITUDINAL AREA OF THE PIPE ADJACENT SAID ZONE DURING BENDING OF THE PIPE; A SECOND, ELONGATED ASSEMBLY DISPOSED IN SPACED, OPPOSED, GENERALLY ALIGNED, PARALLEL RELATIONSHIP TO SAID FIRST ASSEMBLY AND PROVIDED WITH ELONGATED SUPPORT STRUCTURE EXTENDING LONGITUDINALLY OF THE SECOND ASSEMBLY; ELONGATED, RESILIENTLY FLEXIBLE, PIPE-ENGAGING STRIP MEANS DISPOSED OUTWARDLY OF THE SUPPORT STRUCTURE IN GENERALLY PARALLEL, SPACED RELATIONSHIP THEREFROM; RESILIENT SPACER MEANS DISPOSED BETWEEN SAID STRIP MEANS