US3194038A - Tube bender - Google Patents

Description

July 13, 1965 c. B. SMALL ETAL TUBE BENDER 3 Sheets-Sheet 1 Filed March 21, 1962 July 13, 1965 c. B. SMALL ETAL TUBE BENDER 5 Sheets-Sheet 2 Filed March 21, 1962 um ff m. *Il

Wan/5 ATTORNEYS July 13, 1965 c. B. SMALL ETAL TUBE BENDER Filed March 21, 1962 5 Sheets-Sheet 3 m. El-- /@M N ..N| m M R @f m m5 A a7 3 f d MMU. cn ad -1 m... E n

United States Patent O 3,194,033 TUBE BENDER Charles B. Small and Anton l. .laniln Elyria, Ghia, assignors to The Ridge Tool Company, Elyria, Ohio, a corporation of @hin Filed Mar. 21, 1962, Ser. No. 181,327 4 Claims. (Cl. 72--35) This invention relates to tubing or rod benders and more particularly to a tubing or rod bender of the hand-held type which may be used to bend tubing or rods to provide predetermined angles of bend as well as to enable tubing or rods to be bent wherein the laterally or angularly extending portions are of predetermined length and the length of the connecting portions therebetween may be predetermined.

Tubing benders of the class described usually comprise a grooved mandrel, about which and in the groove of which a tube may be bent. A handle .is conveniently attached to the mandrel and a bending shoe or roller having an operating handle is either connected by a link or directly to the axis of the mandrel. A tube is placed alongside the handle, with the place to be bent disposed in the mandrel groove and then the shoe, by means of the handle on the shoe, is brought into contact with the side of the tube which projects outwardly from the sides of the mandrel and rotated around the mandrel to elfect the bending. The foregoing is all old in the art as exemplified by Patent No. 1,824,626, of September 22, 1931.

One of the problems of the prior art has been to hold the tube so that it does not slip around the mandrel as it is being bent. Although this, in many instances, is not too serious a defect, when it is desired to make exact bends in exact places such slipping cannot be tolerated. Heretofore it was common practice to provide a hook or latch, as shown in the aforesaid patent, which was pivotally mounted on the handle adjacent the base of the mandrel and which could be swung over and engage with the tube, which extended parallel to the handle. Although the hook served to prevent the base leg of the tube from swinging out during the bending operation, it did not always prevent the tube from the aforesaid sliding during the bending operation, particularly when the tubing was of the harder drawn type.

In addition to the foregoing, the main handle was usually disposed away from the tube in spaced parallel relation and in some instances was provided with an offset to yassure that it was in such spaced relation in order that the operator could grasp the handle without interference from the tube. The result was, that frequently the operator grasped both the tube and the handle at the same time causing the tube to be bent at a place where it was not intended to be bent or upsetting the number of degrees of bend at the place where it was supposed to be bent. Sometimes the operators hand pushed the tube in the other direction away from the handle, making an undesired reverse bend.

By the present invention We have provided a bending tool where the tube, which extends tangent to the bottom of the groove in the mandrel at the bend starting point, is also seated in a longitudinally extending seat co-extensive with the handle and the bottom of which extends in alignment with the bottom of the groove in the mandrel and on a line tangent to the mandrel at the starting point.

The above feature provides several advantages. Since the tube is seated in the handle groove, both the tube and the handle are grasped at the same time, such gripping causes the tube to be firmly seated in the handle and the friction of the tube with the bottom and sides of the groove resists the tendency for the tube to shift longitudinally during the bending operation.

In addition to the above, the hook or latch for holding 3,1941938l Patented July i3, 1965 the tube provides an additional function to that of merely holding the base leg from outward swinging in that it also presses the tube into the groove, and, with the improved design of hook, which has a cam surface for engaging the tube, causes the tube to be held against slippage even where the portion which is disposed in the groove is so short as to not be conveniently engaged by the lingers of the operator.

The seating of the tube in the handle provides an additional advantage in that the handle, with the tube in position, may be placed in a vise so that on one side one of the jaws engages the handle and the other jaw engages with the tube and presses it into the seat. The depth of the groove is sufficient that the tube is not unduly squashed out since the sides of the groove prevent this result, providing, of course, that normal clamping pressure is used.

Still another advantage resides in the fact that measuring means may be incorporated with the handle with the markings extending up to the edge of the groove and thus markings on the tube may be made at exact dimentional places or previous markings on the tube may be aligned with the marking on the handle to provide more exactitudes of placement of the bends or determining the length of unbent portions beyond the bends. Another feature is that when the tube is in the groove the edge of the groove may be used as a straight edge to enable marking of the tube longitudinally, which marking may be subsequently used to make sure that the bend is in the desired plane.

Another feature of the invention resides in the fact that, with the handle and its groove as stated, the handle and mandrel may be made as one integral element, thus lessening the assembly operations and providing a more sturdy structure.

Heretofore it has also been proposed to make bending tools with scale means for determining the angle of the bend and the distance of the bend from the end of the tube as measured by the handle, such as are illustrated in Patent No. 2,796,785; Netherlands Patent No. 53,402, of October 16, 1942, and Patent No. 2,887,917. These were, however, diicult to use and could not be used with the exactitude required in certain operations. By the present invention we have provided an improved scale means which enables the bends to be performed more accurately and with a minimum of skill.

Still other advantages of the invention, and the invention itself, will become more apparent from the following description of some embodiments thereof, which description is illustrated by the accompanying drawings and forms a part of this specification.

In the drawings:

FIG. 1 is an enlarged elevational view of a bender constructed according to our invention, with a tube to be bent illustrated in dashed lines and also showing in dashed lines an alternate position taken by the shoe at the start of a bending operation;

FIG. 2 is a fragmentary View of the mandrel end of the bender of FIG. 1, showing the shoe rotated to the position taken in making Ia bend;

FIG. 3 is a sectional view taken on the line 3--3 of FIG. 2;

FIG. 4 is a similar view taken on the line 4 4 of FIG. 1;

FIG. 5 is a section on the line 5--5 of FIG. l;

FIG. 6 is a view of a holding hook removed from the mandrel;

FIG. 7 is a view'similar to FIG. 1, illustrating a modified forni of shoe handle;

FIG. 8 is a fragmentary view of the mandrel end of the bender of FIG. 7, showing the position taken by the bending shoe and handle at the start of a bending operation;

FIG. 9 is a plan View of a link used to connect the bendin shoe to the mandrel;

FIG. l`is anelevational View of another form of the invention; Y l FIG. l1 is a fragmentary elevational viewV of the mandrel end ofthe bender of FIG. 10, taken at right ,anglesV generally-circular formation having a portion removed ony a chord at 1-1 and in which, as best shown in FIG. 4, a handle 12 is secured by a pin '13# The mandrel 10is provided with the usualtubejreceivinggroove 14 which extends peripherally around the-mandrel., The groove is of conventional shape, the bottom having a transverse radius the same size as the transverse-radius of the tube and the sides of which extend slightly beyond the center of the tubeas is well known in the-art.

FIG. 12 is a section'taken Ourthe une 1ra-12er FIG. 1o;

The mandrel is also portion lbeing seated in the seat 23. At this time the tube is tangent to the bottom of the groovein the mandrel at the starting point. Then, whenV the hook 16 is rotated counterclockwise the surfaceY 26a comes into engagement with the tube and the tube is pressed firmly into both the mandrel groove and the seat 23. There is more than a y mere holding of the tube against moving outwardfrom the handle by the latch, as in the prior art devices; there is a pressure against the tube which holds it against the mandrel at the starting point (0) and the base leg is also pressed into theV seat. VIn this embodiment the holding is fur-ther increased by the fact that at the point where the hook engages the tube, thetube isout of contact with both the mandrel and the handle seat 23. Thus the resiliency provided with markings which start at V0","this being on a line extending on a radius through the center of the mandrel and which line is normal to the handle, and endingY on 180, whereby the degrees of bend of a tube may beV determined in the conventional manner.

' Adjacent-the mandrel, the handle is formed with a portion of reduced cross-section iat to provide-a cylindrical ,bearing lsurface for a tube engaging hook 1'6. The tube engaging hook or-latch is provided with an eye 17 which is rotatablyjournalled on the part 15, a spring washer l being-interposed between the shoulder formed by the rewasher exerts friction,v between the'latch and the handle enabling itto be adjusted to and stayin anyl desired position.` The latch is provided with Van arm lg'fornger or thumb engagement and a hook 2t) whichis designed toenj gage with Va tube T when swung over the tube. VAsbest shown'in FIG. 6, the tube engaging face 20a of the'hook provides a cam surface which tightens its engagement with the periphery of the tube as thehook is rotated counterclockwise Ainto engagement therewith'. Thatis, the surface 20a is on a plane which departs from a vertical plane by a few degrees, as illustrated in FIG. 6.'Y Y Y The prefered-manner of making the tube engaging surface of the-hook is to make a curved surfacethat is generated by a radius which has Aits axis slightly belowY the center of the eye 1'7, as shown for the hook in FIG. 12. The design is lsuch that the` surface providesra sticking taperffor engagement with the tube surface which holds without sliping. Y

The-above construction also enablesthe manufacturing tolerances to be increased because the slant of the cam surface is suchthatthe tubeis gripped at some point on its surface and does not have to be completely closed upon the tube to provide a good holding effect. It'also lends itself to manufacture by being made of solid material or from aseries of stampings to provide a Vlaminated Struct- Y' ure,rsee-FIG. l0. Y Y Y Y The handle is offset to the left at 22 and then continues of the tube assists in locking the tube in place-andthe holding power is holding the tube against longitudinal as well as swinging movement even though the end that projects Vinto-the seat'2'3 may not necessarily projectalong the seat veryfar; because'of the frictional engagement of the tube inthe bottom of the groove. i

Itisjmore common for the tube to extendsome con- Y siderable distance along the handlev in the tube seat 23,

and, when'it does the operator automatically grasps not only the handle, but along with it, .the tube T when he performs a bending. operation. vIt will be noted that during-the actual bending operation the pressure on the handle and tube .during the bendingis increased in a counter-'clockwise direction, asfviewed in `FIG. l, and therefore the harder the tube is to bend. the greater the pressure and the 'harder' the tube is pressed into the groove. Thus the frictional` engagement of the Ytube in the yseat is increased and the, possibility of longitudinal Y slipping is greatly reduced.` The hook alone, is not enduced portion'lS and the main body of the handle; YThe tirely'relied on at this time for alignment of the tube with the Vmandrel and its'rnain function is to hold the tube in the mandrel groove and seated in the handle and since the tube is seated Vin the' handle it cannot fmove longitudinally and is in fixed relation to the mandrel groove danger of causing a distortion of the tube as is liable to Yoccur in the prior artdevices where the tube is spaced from the handle and Where'such engagement of the tube and the handle at the same time would be liable to cause bending of the tube ina place Where it should not be in a straight linewhich is parallel to a line drawnk through the axis of the mandrel and at from the startingpoint "0 for making bends.AV It is provided witha tube seat23 which extends lengthwise of the handle'substantially coextensive withV the length thereof andrwhich has acrosssectional formation vto conform to the periphery of one It` should also be pointed Vout that the frictional engagement of the tube in the seat 23 may bey enhanced by providing transverse grooving of the seat, by knurling the seat, orby etching or sandblastingthe lseat surface.

l The handle also has a scale onV it whereby the length of the tube'from the center of the tube beyond a bend of 90 tothe. end of or a mark on the tube'in the handle seat may be predetermined. This may include inc or centimeter? markings-24 which areprovided'on the handle Preferably this groove has a cross-sectional' formation` may be'V placed inthe mandrel groove and with one end,

adjacent the seat. The marks extend transversely of the handleand up to the edge of theseat and Vwhenthe tube is in theseat, the marks actually run directly to the tube, thus enabling the tube to be* very accurately positioned 'in the seat or to be measured by the marking on the handle. Por instance, if it is desired to bend a piece' of tubing so that the laterally extending portion after the bend Vris. 1n a'plane normal to the axis of the base leg and 6 from which isl an arcV of less thany 1805?, although'it could havev 7^ the @Ud .'fhefevf', the Vt11b@ S merely Placed UO the Seat with the end of the tube alignedwith the 6 mark on the handley and then the tube is bent.v The marking on the handle may then be considered as starting from the 'extreme end of the mandrel at a place parallel to the handle and beyond the center of the mandrel, either at the outer or inner side of the tube after it is bent. In most modern engineering drawings the dimension lines for tubing are usually drawn with the axis of the tube being the place from which dimensions are computed and therefore the scale is preferably placed on the handle with this in mind. In other words, a point on the handle such as the 6" mark, would be 6 inches fromvthe axis of a laterally extending part of a piece of tubing after being bent.

Another feature of the structure resides in the fact that the seat is preferably designed to receive slightly less than 180 of .the transverse periphery of the tube. In other words, when a tube is seated in the seat 23 slightly more than one-half of the periphery of the tube as considered in transverse cross section, is disposed outwardly of the seat. When the tube is in thi-s position, the edge of the seat may be used as a straight edge, allowing a longitudinal mark to be scribed on the tube. Then, after a tirst bend is made and a second bend is to be made with the bends in the same plane, the mark enables the tube to be shifted in the handle and properly lined circumferentially by the previously applied marking to enable the second bend to be made. This enables all the bends to be made in the same plane with each other.

The bending shoe is arranged to be moved around the mandrel in a conventional manner. A link 30, FIG. 9, is provided for connecting the bending shoe to the mandrel. It is provided with an eye 31 in one end, by which it is connected to the mandrel and another eye 32 in the other end by which it is connected to the shoe. It will be noted that the eye 32 is displaced vertically downward from the eye 31, as viewed in FIG. 9. It also has a lateral extension 33 which bears a marking the purpose of which is to enable a mark or marks on the tube to be aligned therewith, whereby certain types of accurate bends may be made, which will later be described. Adjacent the eye 31 there is provided a stop shoulder 34 whereby the link, the shoe and the mandrel may all be placed in certain predetermined positions.

As best shown in FIG. 4, the eye 31 of the link 30 is pivotally secured to the mandrel by a pin which extends through an aperture in the center or" the mandrel and the eye. The pin has a cylindrical shank 36 which is rotatably journalled in the mandrel. An enlarged head 37 is disposed outwardly of the Ashank on one side of the mandrel and between the head and mandrel there is disposed a spring washer 38 which holds the mandrel and link under frictional tension. The shank 36 of the mandrel pin is provided with a reduced diameter portion 39 which extends through the eye 31 and is `staked or spun over at 40. The pin, washer, mandrel and link are all assembled and then the pin is either spun or staked at the end preferably to lock the pin to the link. The link is held against the shoulder at the junction of the main body 36 and reduced diameter part 39 by the staking or spinning operation. By this construction, and due to the close lit of the .shank 36 in the mandrel, the link is capable of a smooth swingable movement with the pin in the mandrel. The spring holds the pin against endwise movement and thus holds the link pressed against the side of the mandrel with suicient friction that it may be placed in any desired position and will stay in that position. As can best be seen from FIG. 1, the turning movement of the link 30 is limited by the pin 13 which extends beyond the face of the mandrel and is engaged by the stop shoulder 34 when the link is rotated in a counter-clockwise direction, as viewed in FIG. 1, and where it is shown in the stop position.

The forming shoe 43 is rotatably connected to the link and has a handle 44 whereby it .may be rotated on the link, and, with the link, rotated .around the mandrel, to provide the desired bends. As best shown in FIG. 1, it comprises va shoe body 43 having a longitudinal-ly extending groove 45 of arcuate or semi-circular cross-sect-on. :'Io the right of the shoe groove there is provided an eye 46 by which it is pivotally attached to the link 3h. The attachment to the link is made in the same manner as the yattachment of the link to the mandrel and includes a headed pin 47 which is rotatably journalled in the shoe with :a spring washer 4S, FIG. 12, between the head and the :shoe `and with the pin secured in the link as described. There -is thus a frictional connection between the shoe and link.

The end of the shoe 43 is cut away obliquely, FIG. 8, so that it intersects the outer edges of the groove 45 .at the starting point for a bend when the shoe is in the bend starting position. By this expedient, when the shoe is rotated from the position shown in FIG. 1 into a position for the start of a bending operati-on, at the time when the shoe comes into engagement with the tube, the movement of the shoe .is substantially normal to the axis of the tube. This formation has several advantages in that a greater clearance between the shoe and the mandrel is provided for insert-ion of a tube between the shoe and mandrel and the mandrel handle ldoes not have to be rotated as far toward the open position of FIG. 1, to enable the tube to be placed in position. Furthermore the process of bringing the shoe into operative engagement with the tube is not accompanied 4by any distortion or nicking of the tube as the mandrel comes into position or of frictional engagement with `the tube at that time which might cause the tube to be moved from the desired position longitudinally relative to the handle and mandrel.

At the start Iof a bending operation, the link 30 should be in the position shown in FIG. 1, with the sto-p shoulder 34 :against the pin 13. This position is relatively easy .to obtain and hold because of the frictional engagement of the link with the mandrel. When the shoe is rotated by the handle to the tube engaging position, a starting mark 51 on the shoe is automatically aligned with the 0 starting mark on the mandrel. The forming groove 45 0n the sho-e is preferably less .than 180 in transverse section and extends for substantially the full length of the shoe as indi-cated. The shoe is provided with a rais-ed side face or boss 52 which is 4coextensive with the groove and which extends to and surrounds the pin 47. A pin 53 `set into the shoe and extending from the side thereof, FIG. 12, is positioned to engage with the tongue or scale extension part 33 on the link when moved from the position shown in FIG. 1 to that of FIG. 8. This being the time when the bend is to be started. -Thus the movement `of the shoe toward the mandrel is -at all times limited 'and at no time .can the tube be squashed between the `shoe and the mandrel land the shoe slides easier over the surface of the tube `during the for-ming operation.

The shoe handle may `also be provided with a scale marking 24a and may also be used for measuring the length of the tube T disposed in the seat in the handle since it corresponds to the same marking as :at 24. In FIG. 7, the handle 44a is yshown `as being offset toward the handle 22. This enables the scale 24a on the handle to be brought into close proximity to the tube, when in the position shown in FIG. 7. This also has the advantage, that when the lhandle is moved to the position shown in FIG. 8 .the marking on the shoe handle may be so arranged that they may be used to measure the extension of the tube T beyond the end of the mandrel .and also when in the position as shown in FIG. 2 theV extension of the tube beyond the bend. Otherwise the disclosure of FIGS. 7 and 8 is identical to that of FIGS. 1 vand 2.

As previously mentioned, it is possible with the tool of our invention to provide more accurate formation of a piece of tubing into bends of different degrees and with the desired length of the straight runs of the tube between the bends, and the Vdesired length of tube beyond the bends. .This s brought about by the fact that there is a predetermined `fixed relation lbetween the link .and

7 t Y. t-he mandrelV due to the engagementfof the link'withvthe stop pin -13 on the mandrel and the link and the .shoe due to the engagement ofthe pin 53on'the shoe with the extension 33 on the link. i .v

vSlt should also be noted that the marking "0, "45, R and "90 on the extension 33 of the link, as shown in .the full linesv of FIG. 1, aregclearly visab-le for use in conjunctionwith marks that may be placed gon the tube because the markings are outwardly of the vtube :andthe .shoe is in an open position and therefore the tube can -be easily moved Vprior to engagement 'by the latch ,16 or the shoe. The markings being on, the llink' are not apt rto become obliterated due to ordinary wear. Theyare also in a fixed position where .they mayr be correlated with the tube when the shoe is in the 4open position :and at which time the tube .may be easly moved Yand thereby providing a more precise Vplacement of the'tube in its proper longitudinal position.`

For instance, the markl 0" on the link is on 1a radius Y extending through the axis ofthe mandrel and which radius is lnormal to the handle and -a ltu'be T seated in lthe seat 23 .and the groove in'themandrel. -It is al-so coincident withV the tangent point of the tube with the mandrel. AIf it was rdesired to make abend using 'a given or calculated dimension from a particular fixed' point on the tube, which could be but is not necessarily the end, to the `start of a bend ofany` kind', it is Amerely necessary =to measure the distance fromthe fxedpoint to the desired start of .the bend, mark rthe tube at this place .and then place the tube `in the handle seat and mandrel (with the link in the FIG. 1Y position) with the mark on thetube flo opposite to the 0 mark on the link'orthe mandreland Y proceed with'the bend. Y

V'I oward the end of the extension 33 on the link, is the mark 90. This mark is displaced fromthe 0 mark by a distance equal to the length of a radius extending nor.- Y,

point tothe mandrel. It is used for makingy a 90 Vbend' wherein the lengh from the end or a fixed point on the tube to the center line of the tube after the bend maybe.

determined. In this instance, the length from the 'fixed g -jl'lhen the second dimension on 'the drawing, which is the distanceifrom thecenter linegof the base leg to the center vline of theV return bend, is marked on the bent leg of Vthe ld istance'apart. Itis pointed out that the first bend could have been a bend, in which instance the'second mark vs /OuldY lfravcbelenmeasured from the intersection of center'lincs of the tube at. the iirstwbend. VAfter the rst bend, succeeding ybends of any desired number may be made by following the above procedure. f

fAs showninFlG. l3,the side of the'handle 72 opposite to that of FIG. l, is marked with a series of marks 0 to 4? entitled gaini These markings are used when it is desired to pre'cut the tube to-length prior to bending and thus avoiding waste. These'markings areused inV conjunction with the scale 24, ya-nd represent the difference in dimensional length of tube needed to make a bend shown on a drawing where the drawing does not 'show the 'actuall length of tube needed.A This is the difference between the length of tube actually needed and lthe sum of the dimensions shown in the drawingl When a bend is shownina drawing it may be shown as a right angle. When the tube is bent, how- V everithe bend isactuallyan arc and there is less tube in Vthe bend lthan'is shown on the drawing and this 'diliierence is equal to 'AZR for each 90 bend.l Therefore, the'distance'between each of theV marks 0-192-'73- i of FIG. 13 is $43k.V If a piece of tube is ,to be bent having` two 90 bends, the dimensions from the drawings are first totalled and the tube is markedwitha length'equal to this total. Thenfthe tube is placed in the .handle seat with the marking opposite 2 with the base end of the tube extending in thedirection ofand beyond the zero mark. The tube andthere is no waste. Y Y yAnother feature. ofV this is the fact that the tube may be precutV to theA exact length needed toy enable it to berbent point or endof the tube to the axis of the'lateral leg of Y the tube is marked on the tube. The tube is then placed in the mandrel and handle with the mark lined up with V90 mark on the link, the tube is then secured by the hook and the Vtube bent. This has the advantage that a piece of tubingof any length can be bent to exact dimensions which are usually 'given on drawings to the center. line of the laterally extending portions. Y Y

The mark"45 on the link 3) is used in conjunction with making a 45 bend. Such bends are measured from a fixed point on the tube, to the intersection of the center lines of the'legs. In making such va bend, a` distance` isA first measured on the base leg of the tube, which will seat in the seat 23, to the point of intersection *of the center lines and Vthis point is marked on the tube. The tubeisk `then placed inthe bender` with theV mark at 45`and 'thenV the tube is bent. The mark45 is located on the'link at a point` beyond "0 on the link which is equal to Vtan L/Z R where Lis the angle ofthe bend and R is the .4.5 Y handleand bent.

/ without any further marking. Forexample, in making a ffU b end, Vthe cuttube is placed in the bender and the first leg end placed vopposite 'the `desired scale mark on the Then the'tubc is reversed and the second legot, the` tube placed opposite the proper scale mark,

.i f0 to 180.V The handlet72 is integral with the mandrel and'- extends from thernandrel at one side of the axis of radius from the center of theman'drel to the center line 'p of thetube in the bend, at the place where itis tangent to thelmandrel at'thestart ofthe bend.V Thisformula may also be4 applied to the position of the "90 mark;

The mark R on the link is formaking afreverse or U shaped Vbend where the second bend is made from They after'the first bend. This distance is marked onfthe tube.v Y

The tube is then bent using'the 90 mark as described;

the mandrel.V

Spaced' fromthe'mandrel and extending opposite to the basefof the V'mandrel is a boss 73. The boss 73 and the mandrel arerboth `drilled to provide a bore'for receiving a latch or hook securing pin '74 on which is'swingably mounted alatchle having' a 'ngerengaging'portion i9 and the tube `engaging 11001520 with tube engaging face 20a. A spring washer, not shown but which may beV simiz lar to'that shown in `FlG.` l, may 4be Vplaced around the of the Vsame .conformation as the groove 23 in the device .of'PlGn l. Thergroove is provided with a reliefV at 75a whiche'xtends from a'point close tothe starting point ,0

and for a short distance toward the end of the handle. ri`his relief is such that in this Zone, which is opposite the hook E@ and substantially coextensive in length with the width of the hook, or slightly larger, the tube is unsupported at this point and therefore the resiliency of the tube T assists in the holding engagement thereof by the hoo): in the mandrel and handle grooves in the same manner as that of FIG. 1.

Adjacent the boss 73 and extending toward the end of the handle there is provided a surface 72a which is preferably dat and is parallel to the bottom of the groove This enables the device, along with a tube seated in the handle, to be gripped in a vise.

The only other material difference between this embodiment and the previously described embodiments, is that the stop pin 76, which corresponds to the stop pin 13 of FIG. l, is disposed to the left of the axis of the mandrel and the link '77 is provided with a straight edge 78 which engages with the stop pin and limits rotation of the link in a counterclockwise direction.

The handle 44- and its shoe l5 are the same as previously described. The link is attached to the handle and the mandrel in the same manner as described for 1G. l. The operation of the device is in all respects similar to that of FlGS. 1 and 7.

The latches 16 and 7d may both be of laminated construction as illustrated in FlG. 11. The links 3@ and 77 may also be laminated.

Having thus described the invention in some embodiments thereof, we are aware that numerous and extensive departures may be made therefrom without departing from the spirit or scope of the invention as defined in the appended claims.

We claim:

1. A tube bender comprising a mandrel of generally circular configuration having a peripheral tube receiving groove exending from a bend starting point around said mandrel at least 90 and a handle connected to the base thereof, means for holding a tube in said mandrel, a bending shoe for association with said mandrel to bend a tube therein, and a link for connecting said bending shoe to the mandrel, ysaid link being pivotally connected at one end to the mandrel coincident with the axis of said tube receiving groove, stop means on said mandrel for limiting the rotation of said link around said pivot and arranged to stop said link in a predetermined position at said bend starting point for the start of a tube bending operation, said shoe being pivotally connected to the other end or said link, said shoe having a tube engaging seat therein and link engaging means on said shoe for engagement with said link upon a predetermined pivoting of the lil shoe on the link and to hold said link and shoe in fixed relation to each other when the shoe and link are rotated around the mandrel, said link being provided with a portion arranged to extend along a tube to be bet when in position in the mandrel and handle and having tube locatig markings arranged for juxtaposition to a point on the tube for determining the position of the -tube in the mandrel for a bend of a predetermined character.

2. A device as described in claim li, wherein said link is provided with a projection for engagement With said link engaging means on the shoe which extends parallel to a line extending from the axis of generation of the mandrel groove circumferentially and through `the groove at from the starting point and tube locating markings are provided on the link and disposed along the projection arranged for juxtaposition to a selected point on the tube for determining the position of the tube in the mandrel for a bend of a predetermined character.

3. A device as described in claim 2, wherein markings are displaced from the bend starting point by a distance equal to tan L/ 2 R Where R is is the radius from the center or the mandrel to the center of a tube seated in the mandrel and L is the degree of the angle to be bent.

A device as described in claim 1, wherein a lirst mark'ng of said markings is provided extending in alignment with a radius from the axis of the mandrel to the starting point of the bend and a second marking is provided normal to said radius and one radius length from the iirst marking wherein said radius is from axis of the mandrel to the center line of the tube in the seat at the bend starting point.

References Cited by the Examiner UNlTED STATES PATENTS 361,398 4/87 Daniels. 1,712,414 5/ 29 Allen. 1,832,698 1l/31 Gale. 2,127,185 8 3 8 Parker. 2,422,1 14 6/47 Matter. 2,796,785 6/57 Philippe. 2,831,382 4/58 Klamm. 2,887,917 5/59 Kowal. 2,955,495 10/ 60 Stirling.

FOREIGN PATENTS 53,402 l l/ 42 Netherlands.

WILLIAM FELDMAN, Primary Examiner.

WALTER A. SCHEEL, Examiner.

Claims (1)

1. A TUBE BENDER COMPRISING A MANDREL OF GENERALLY CIRCULAR CONFIGURATION HAVING A PERIPHERAL TUBE RECEIVING GROOVE EXTENDING FROM A BEND STARTING POINT AROUND SAID MANDREL AT LEAST 90* AND A HANDLE CONNECTED TO THE BASE THEREOF, MEANS FOR HOLDING A TUBE IN SAID MANDREL, A BENDING SHOE FOR ASSOCIATION WITH SAID MANDREL TO BEND A TUBE THEREIN, AND A LINK FOR CONNECTING SAID BENDING SHOE TO THE MANDREL, SAID LINK BEING PIVOTALLY CONNECTED AT ONE END TO THE MANDREL COINCIDENT WITH THE AXIS OF SAID TUBE RECEIVING GROOVE, STOP MEANS ON SAID MANDREL FOR LIMITING THE ROTATION OF SAID LINK AROUND SAID PIVOT AND ARRANGED TO STOP SAID LINK IN A PREDETERMINED POSITION AT SAID BEND STARTING POINT FOR THE START OF A TUBE BENDING OPERATION, SAID SHOE BEING PIVOTALLY CONNECTED TO THE OTHER END OF SAID LINK, SAID SHOE HAVING A TUBE ENGAGING SEAT THEREIN AND LINK ENGAGING MEANS ON SAID SHOE FOR ENGAGEMENT WITH SAID LINK UPON A PREDETERMINED PIVOTING OF THE SHOE ON THE LINK AND TO HOLD SAID LINK AND SHOE IN FIXED RELATION TO EACH OTHER WHEN THE SHOE AND LINK ARE ROTATED AROUND THE MANDREL, SAID LINK BEING PROVIDED WITH A PORTION ARRANGED TO EXTEND ALONG A TUBE TO BE BENT WHEN IN POSITION IN THE MANDREL AND HANDLE AND HAVING TUBE LOCATING MARKINGS ARRANGED FOR JUXTAPOSITION TO A POINT ON THE TUBE FOR DETERMINING THE POSITION OF THE TUBE IN THE MANDREL FOR A BEND OF A PREDETERMINED CHARACTER.

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