US3750447A

US3750447A - Tube bender

Info

Publication number: US3750447A
Application number: US00184567A
Authority: US
Inventors: L Kowal; W Saddler
Original assignee: IMP Eastman Corp
Current assignee: Imperial Eastman Corp; IMP Eastman Corp; Pullman Co
Priority date: 1971-09-28
Filing date: 1971-09-28
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07
Also published as: JPS4841967A; DE2247412C2; JPS551132B2; DE2247412A1

Abstract

A manually operable tube bender wherein a straight tube is inserted between a mandrel and a bending shoe with the bending shoe being swung about the axis of the mandrel groove to progressively bend the tube into the groove. A hook is provided for preventing longitudinal movement of the tube as a result of the friction forces generated by the sliding of the hook against the tube as it is bent. A number of different forms of such hooks are disclosed for providing improved tube retention.

Description

1451 Aug. 7. 1973 United States Patent [191 Kowal et al.

[ TUBE BENDER Lundis 72/460 2/1933 Lidseen.................. 72/159 .w v 8 D 7 6 9 H .1 38 9 09 31 1 .w e e Hk mm W. sm mG m d oa KS k mm n h h w n LWo r o t n e V n I M 7 1 [73] Assignee: Imperial-Eastman Corporation, Examinercharles Lanham Chica o, [11, Assistant ExaminerM. .I. Keenan AttorneyHofgren, Wegner, Allen, Stellman & McCord [22] Filed: Sept. 28, 1971 [21] Appl. No.: 184,567

[57] ABSTRACT A manually operable tube bender wherein a straight tube is inserted between a mandrel and a bending shoe with the bending shoe being swung about the axis of the mandrel groove to progressively bend the tube into the cove. A hook is provided for preventing longitudinal movement of the tube as a result of the friction forces generated by the sliding of the hook against the tube as r g 98 8 SW38 M34 1 7, WW ,1 M 7 5, 1 24.4 2 7 I 9129 91 l 3 d ,1 .e B "4 C mum mmms c u 4 n n. e 2 u ""1 "mh h mum R "8 flu L C smm I i UmF 12 l 2 8 6 555 5 [1.1. .l

UNTED STATES PATENTS it is bent. A number of different forms of such hooks are disclosed for providing improved tube retention.

72/459 18 Clnlma, 10 Drawlng Figures 2,927,490 3/1960 2,709,382 5/1955 Safranski 1,835,264 12/1931 PATENTED AUG 7 i975 lnvenib rs:- Z eonard JKO wal, SaddZev;

TUBE BENDER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to tube benders and in particular to hand operated tube benders wherein the tube is held by a hook member during the tube bending operation.

2. Description of the Prior Art In the conventional hand operated tube bender, a mandrel is provided with a peripheral groove. A bending shoe is swingably associated with the mandrel to move around the periphery of the mandrel and urge a tube progressively into the mandrel groove to effect a desired bend therein.

To prevent longitudinal movement of the tube during the bending operation, which may occur as the result of friction forces generated by the shoe as it moves along the tube surface in effecting the bend, hook or clamp means have been provided. In one improved form of such a tube bender, such as shown in Philippe U.S. Pat. No. 2,796,785, issued June 25, 1957 for a Tube Bender, a hook 14 is provided on the handle 13 to pivot about an axis perpendicular to the axis of the mandrel groove. Thus, in use of the tube bender thereof, the user inserts the tube to be bent between the shoe and the mandrel and pivotally swings the hook into tube-engaging disposition.

In the concurrently issued patent to Kowal et al., U.S. Pat. No. 2,796,784, issued June 25, 1957 for a Tube Bender, a modified form of such tube bender is shown to include a hook having a wedge element 16 associated therewith for locking the tube more firmly to the hook during the bending operation.

In Franck U.S. Pat. No. 2,979,976, issued Apr. 18, 1961 for a Plier-Type Tube Bending Tool, the hook is shown to be pivotally mounted to the mandrel for pivoting it about an axis perpendicular to the mandrel axis.

In the conventional hook construction, the portion of the hook engaging the tube is made to be arcuate in general conformity of the shape of the tube to be bent, as illustrated in the above-indicated prior art patents.

SUMMARY OF THE INVENTION The present invention comprehends an improved tube bender wherein the hook is provided with a straight edge for improved coaction with the tube to be bent. The invention comprehends that the mandrel may be provided with a plurality of axially spaced coaxial grooves for use in bending different size tubes. Alternatively, the invention comprehends providing a mandrel with a single bending groove adapted for bending different size tubes by means of the straight hook edge. The mandrel may be provided with suitable scale markings corresponding to the different size tubes for use in controlling the desired angular extent of the bend with the different size tubes.

The straight edged hook may be fixedly associated with the mandrel-handle structure, and in the illustrated embodiment, comprises an integral extension thereof.

In a modified form, the straight edged hook is adapted to swing about an axis parallel to the mandrel axis with the swinging movement limited in the direction of urging of the tube by the shoe during the bending operation, by means of a stop fixedly associated with the handle and mandrel.

In a further modified form of the invention, the hook is slidable in a suitable recess between a retracted position permitting the tube to be installed between the mandrel and shoe in the bend-start arrangement, and an operative position wherein the hook engages the tube to prevent longitudinal movement thereof during the bending operation. The hook may be resiliently p0- sitioned in the tube "bender, and in the illustrated embodiment, is biased to the tube-engaging position.

In each of the different forms, the hook is provided with a tube-holding rear edge portion adapted to en gage an outer portion of the tube to effect the desired retention thereof against longitudinal movement during the bending operation.

BRIEF DESCRIPTION OF THE DRAWING Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:

FIG. 1 is a side elevation of a tube bender provided with a hook structure embodying the invention;

FIG. 2 is a broken end view thereof;

FIG. 3 is a fragmentary end view looking in a direction opposite to that of FIG. 2 and with the shoe omitted to facilitate illustration of the remaining structure;

FIG. 4 is a fragmentary horizontal section taken substantially along the line 4-4 of FIG. 1;

FIG. 5 is a fragmentary end elevation of a modified form of tube bender embodying the invention;

FIG. 6 is a fragmentary side elevation of the mandrel element of the tube bender of FIG. 5;

FIG. 7 is a fragmentary end elevation of a further modified form of tube bender embodying the invention;

FIG. 8 is a fragmentary side elevation of the tube bender of FIG. 7;

FIG. 9 is a fragmentary side elevation of a further modified form of tube bender embodying the invention; and

FIG. 10 is a fragmentary end elevation thereof with a portion shown in section to facilitate the illustration of the hook structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the exemplary embodiment of the invention as disclosed in FIGS. l4 of the drawing, a tube bender generally designated 10 is shown to comprise a mandrel l 1 having a peripheral tube bending groove 12 in which a tube T is bent by means of a shoe 13 swingable about the axis 14 of the mandrel groove by means of a connecting link 15 pivotally connected to the mandrel by a pivot 16 and to the shoe by a pivot 17. A handle 18 is connected to shoe l3 and a handle 19 is connected to mandrel 11 for suitable manipulation of the tool to effect a hand operation thereof in bending the tube T to a desired angularity, as illustrated in FIG. 1.

Handle 18 is provided with a stop pin 20 adapted to abut against a shoulder portion 21 of the connecting link 15 when the shoe is in the tube-bending position of FIG. 1. Swinging of the handle in a counterclockwise direction from the position of FIG. 1 permits a displacement of the shoe 13 from the tube-engaging position for facilitated installation of the tube T between the mandrel and shoe in placing the tube in the tool at the initiation of the tube-bending operation.

The invention comprehends providing an improved hook means generally designated 22 in the tool for improved facility in bending of the tube T. As shown in FIG. 2, hook means 22 defines a hook having a straight tube-engaging portion 23 aligned with the mandrel groove 12 for holding the tube T against longitudinal movement as the shoe 13 is swung in a clockwise direction (see FIG. 1) from a bend-start point 24. The tubeholding portion includes a leading edge 25 adapted to be urged into the outer portion of the tube as a result of the friction forces of the shoe urging the tube forcibly against the hook edge 25, as illustrated in FIG. 1.

Mandrel ll may be provided with a plurality of tubebending grooves. Thus, as shown in FIG. 2, groove 26 and groove 27 may be provided in addition to groove 12 accommodating tubes of successively smaller diameter whereby the tool is adapted to bend different size tubes by suitable placement thereof in the corresponding mandrel groove and with the tube engaging the hook edge portion 25 similarly in each instance. The

mandrel grooves

12, 26 and 27 are coaxially disposed on the mandrel in spaced axial relationship so that the bending operation is similar in each instance.

It has been found that with the use of the straight edge hook 22, a mandrel having three grooves, such as

grooves

12, 26 and 27, may accommodate the entire range of conventional tube sizes from under onesixteenth inch up to one-fourth inch where the grooves have radii as follows: groove 12 approximately 0.125 inch to 0.127 inch; groove 26 approximately 0.093 inch to 0.095 inch; and groove 27 approximately 0.062 inch to 0.064 inch. The inner radius of groove 12 relative to the mandrel axis may be approximately 0.435 inch, the inner radius of the groove 26 to the mandrel may be approximately 0.498 inch, and the inner radius of groove 27 to the mandrel may be approximately 0.560 inch. The inner edge 25 of the hook may be spaced from a line perpendicular to the handle 19 through the mandrel axis 14 approximately 0.685 inch and the hook may have a width of approximately seven-sixteenths inch, i.e., parallel to the tube T, as shown in FIG. 1.

By virtue of the fact that the tube may swing somewhat about its contact point with the mandrel in the bending groove depending on the cross-sectional diameter of the tube, the tool 10 is adapted to accommodate in each of the grooves, tubing having smaller crosssections than that for which the groove is specifically designed. Thus, as illustrated in FIGS. 5 and 6, where a substantially smaller diameter tube is inserted in the mandrel groove 12, the tube assumes a position relative to the mandrel wherein the tube T becomes tangent to the groove 12 at a point 28 spaced angularly from the bend-start point 24 a small distance resulting from the elevation of the lefthand end of the tube T' into abutment with the hook edge 25 rearwardly of the bendstart point. Thus, the scale means 29 of the tool 10, as shown in FIG. 1, is augmented by a supplementary scale means 30 displaced angularly from scale means 29 throughout an amount equal to the spacing of bendstart point 28 from bend-start point 24. Where the tube has only a slightly smaller diameter than that of the groove, the scale markings 29 may be utilized by the user making only a slight compensatory adjustment in the position of the shoe at the end of the bend, i.e., positioning the shoe slightly beyond the angular marking desired. Thus, as discussed above, the multiple groove mandrel 11 may be utilized to accommodate a wide range of different diameter tubes with the three mandrel grooves thereof.

Turning now to FIGS. 7 and 8, a further modified form of tube bender embodying the invention is shown to comprise a tube bender generally designated I10 generally similar to tube bender 10 but having a straight edge hook 122 pivotally mounted to the handle ll9-mandrel lll structure by means of a pivot 13] having its axis 132 parallel to the axis 114 of the mandrel. A stop 133 is provided on the handle ll9-mandrel lll structure for limiting the pivotal swing of the hook in a forward direction, i.e., clockwise as seen in FIG. 8, thereby to cause leading edge 125 to retain the tube against longitudinal movement in the same manner as effected by edge 25 of hook 22 in tool 10 in the bending operation.

As will be understood by those skilled in the art, the hook 122 may be pivotally mounted in the tool to swing about an axis perpendicular to the mandrel axis in the conventional manner with the straight edge portion 125 cooperating with the tubing during the bending operation in the improved manner of hook 22 of tool 10.

As shown in FIGS. 9 and 10, a further modified form of tube bender generally designated 210 is shown to comprise a straight edge hook 222 comprising a block mounted in an extension 234 of the handle-mandrel structure forselective positioning for engagement with the tube, or in a retracted disposition in the support 234 permitting facilitated mounting of the tube in the too]. As shown, the block 222 is slidably received in a corresponding square bore 235 in extension 234 and is biased into overlying association relative to the tube by a coil spring 236 received between an inturned shoulder 237 on the extension 234 and the inner end of the block 222. A retainer rod 238 extends outwardly from the inner end of the block 222 through the outer end of the bore 235 and is provided at its outer end with a finger manipulating button 239 for selectively retracting the block against the biasing action of the spring 236. Block 222 defines a tube-retaining edge 225 which functions similarly to edge 25 of hook 22 in tool 10 to retain the tube against longitudinal movement during the bending operation. Edge 225 comprises a straight edge similar to straight edge 25 of the tools illustrated in FIGS. 1-6 and the edge 125 of the tool 110, in providing the improved tube-holding functioning discussed above. As will be obvious to those skilled in the art, the block 222 may be elongated and the mandrel 211 of the tool 210 may be provided with a plurality of different size grooves in conformity with the structural concepts embodied in

mandrels

11 and 111 within the scope of the invention. In each case, use of the straight groove permits a range of tube sizes to be bent in the tube bender to provide further improved tube-holding action. The stop 133 may be omitted in the tool permitting the hook 122 to swing sufficiently to abut any size tube being bent in the tool. Thus, the inventive concepts embodied in the different illustrative embodiments provides an improved tube-bending function by extremely simple and economical means.

The foregoing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.

We claim:

1. In a hand tube bender having a mandrel provided with a peripheral tube-bending groove extending about a mandrel axis and defining a bend-start point at one end, a handle connected to said mandrel, a bending shoe, and means for swinging the bending shoe coaxially circumjacent said mandrel groove from adjacent said bend-start point in a forward direction away therefrom with a tube to be bent received therebetween, improved means for retaining the tube to be bent therebetween against axial displacement during a tube-bending operation comprising: a hook disposed rearwardly adjacent said bend-start point having a straight, planar tube-holding surface extending parallel to the mandrel groove disposed to engage an outer portion of the tube spaced from the mandrel groove rearwardly of the bend-start point to preclude radial constrictive clamping of the tube in the mandrel groove while yet holding the tube against longitudinal movement while the shoe is swung against the outer portion of the tube from said bend-start point forwardly thereof to press the tube into the mandrel groove and thereby form a desired bend therein.

2. The tube bender means of claim 1 wherein said hook is fixedly connected to said handle.

3. The tube bender means of claim 1 wherein said mandrel is provided with a plurality of different coaxial size bending grooves in axial side-by-side relationship spaced from said mandrel axis different distances preselected so that the outer portion of each tube received therein having an outer diameter corresponding to the size of the groove is spaced from said mandrel axis at the bend-start point the same distance whereby each tube engages the straight tube-holding surface similarly.

4. The tube bender means of claim 1 wherein said mandrel is provided with a plurality of different coaxial size bending grooves in axial side-by-side relationship spaced from said mandrel axis different distances preselected so that the outer portion of each tube received therein having an outer diameter corresponding to the size of the groove is spaced from said mandrel axis at the bend-start point the same distance whereby each tube engages the straight tube-holding surface similarly, and said shoe is provided with a plurality of tubeengaging grooved surfaces aligned with the respective mandrel grooves, each shoe groove having a size corresponding to the confronting mandrel groove, the outer portion of each shoe groove being aligned with said straight tube-holding surface when the shoe is disposed at the bend-start position.

5. The tube bender means of claim 1 including means for pivotally mounting the hook to swing about an axis parallel to the mandrel axis and means for limiting the forward swinging movement to a preselected position when the hook holdingly engages the outer portion of the tube.

6 The tube bender means of claim 1 including means for pivotally mounting the hook to swing about an axis parallel to the mandrel axis and a stop shoulder on said connected mandrel and handle structure for limiting the forward swinging movement to a preselected position when the hook holdingly engages the outer portion of the tube.

7 The .tube bender means of claim 1 wherein said hook comprises an integral extension of said handle.

.8. In a hand tube bender having a mandrel provided with a peripheral tube-bending groove extending about a mandrelaxis and defining a first bend-start point at one .end, a handle connected to said mandrel, a bending shoe, and means for swinging the bending shoe coaxially circumjacent said mandrel groove from adjacent said bend-start point in a forward direction away therefrom with a tube to be bent received therebetween, improved means for retaining the tube to be bent therebetween against axial displacement during a tube-bending operation comprising: a hook disposed rearwardly adjacent said bend-start point having a straight, planar tube-holding surface extending parallel to the mandrel groove disposed to engage an outer portion of the tube spaced from the mandrel groove rearwardly of the bend-start point to preclude radial constrictive clamping of the tube in the mandrel groove while yet holding the tube against longitudinal movement while the shoe is swung against the outer portion of the tube from said bend-start point forwardly thereof to press the tube into the mandrel groove and thereby form a desired bend therein; and scale means on the mandrel indicating said bend-start point and a second, displaced bendstart point correlated with the position assumed by a tube having a smaller diameter than that of a full size tube to be bent by said tool as a result of an angular shift of the smaller diameter tube in extending rectilinearly between said hook and the mandrel groove.

9. The tube bender means of claim 8 wherein said scale means includes first bend-finish indicia corresponding to different angular degree bends from said bend-start point and second bend-finish indicia displaced similarly as said second bend-start point for indicating different angular bends of the smaller diameter tube.

10. In a hand tube bender having a mandrel provided with a peripheral tube-bending groove extending about a mandrel axis and defining a bend-start point at one end, a handle connected to said mandrel, a bending shoe, and means for swinging the bending shoe coaxially circumjacent said mandrel groove from adjacent said bend-start point in a forward direction away therefrom with a tube to be bent received therebetween, improved means for retaining the tube to be bent therebetween against axial displacement during a tube-bending operation comprising: a hook disposed rearwardly adjacent said bend-start point having a straight, planar tube-holding surface extending parallel to the mandrel groove disposed to engage an outer portion of the tube spaced from the mandrel groove rearwardly of the bend-start point to preclude radial constrictive clamping of the tube in the mandrel groove while yet holding the tube against longitudinal movement while the shoe is swung against the outer portion of the tube from said bend-start point forwardly thereof to press the tube into the mandrel groove and thereby fonn a desired bend therein; and means for guiding said hook in a rectilinear path parallel to said mandrel axis selectively to and from a position wherein the hook engages the tube at said portion rearwardly of the bend-start point.

11. The tube bender means of claim 10 wherein said hook comprises a slide block, said tube bender includes support means connected to said handle and having a recess slidably receiving said slide block, and means for selectively retracting said slide block to permit placement of said tube in position in the tube bender without interference by said hook slide block.

12. The tube bender means of claim 10 further including means for biasing said hook to the tubeengaging position.

13. The tube bender means of claim 10 wherein said hook comprises a slide block, said tube bender includes support means connected to said handle and having a recess slidably receiving said slide block, and means for selectively retracting said slide block to permit placement of said tube in position in the tube bender without interference by said hook slide block, and means for biasing said slide block to the tube-engaging position.

14. The tube bender means of claim 10 wherein said recess and slide block are polyhedral in cross-section.

15. The tube bender means of claim 10 including

Claims

4. The tube bender means of claim 1 wherein said mandrel is provided with a plurality of different coaxial size bending grooves in axial side-by-side relationship spaced from said mandrel axis different distances preselected so that the outer portion of each tube received therein having an outer diameter corresponding to the size of the groove is spaced from said mandrel axis at the bend-start point the same distance whereby each tube engages the straight tube-holding surface similarly, and said shoe is provided with a plurality of tube-engaging grooved surfaces aligned with the respective mandrel grooves, each shoe groove having a size corresponding to the confronting mandrel groove, the outer portion of each shoe groove being aligned with said straight tube-holding surface when the shoe is disposed at the bend-start position.

6. The tube bender means of claim 1 including means for pivotally mounting the hook to swing about an axis parallel to the mandrel axis and a stop shoulder on said connected mandrel and handle structure for limiting the forward swinging movement to a preselected position when the hook holdingly engages the outer portion of the tube.

7. The tube bender means of claim 1 wherein said hook comprises an integral extension of said handle.

8. In a hand tube bender having a mandrel provided with a peripheral tube-bending groove extending about a mandrel axis and defining a first bend-start point at one end, a handle connected to said mandrel, a bending shoe, and means for swinging the bending shoe coaxially circumjacent said mandrel groove from adjacent said bend-start point in a forward direction away therefrom with a tube to be bent received therebetween, improved means for retaining the tube to be bent therebetween against axial displacement during a tube-bending operation comprising: a hook disposed rearwardly adjacent said bend-start point having a straight, planar tube-holding surface extending parallel to the mandrel groove disposed to engage an outer portion of the tube spaced from the mandrel groove rearwardly of the bend-start point to preclude radial constrictive clamping of the tube in the mandrel groove while yet holding the tube against longitudinal movement while the shoe is swung against the outer portion of the tube from said bend-start point forwardly thereof to press the tube into the mandrel groove and thereby form a desired bend therein; and scale means on the mandrel indicating said bend-start point and a second, displaced bend-start point correlated with the position assumed by a tube having a smaller diameter than that of a full size tube to be bent by said tool as a result of an angular shift of the smaller diameter tube in extending rectilinearly between said hook and the mandrel groove.

10. In a hand tube bender having a mandrel provided with a peripheral tube-bending groove extending about a mandrel axis and defining a bend-start point at one end, a handle connected to said mandrel, a bending shoe, and means for swinging the bending shoe coaxially circumjacent said mandrel groove from adjacent said bend-start point in a forward direction away therefrom with a tube to be bEnt received therebetween, improved means for retaining the tube to be bent therebetween against axial displacement during a tube-bending operation comprising: a hook disposed rearwardly adjacent said bend-start point having a straight, planar tube-holding surface extending parallel to the mandrel groove disposed to engage an outer portion of the tube spaced from the mandrel groove rearwardly of the bend-start point to preclude radial constrictive clamping of the tube in the mandrel groove while yet holding the tube against longitudinal movement while the shoe is swung against the outer portion of the tube from said bend-start point forwardly thereof to press the tube into the mandrel groove and thereby form a desired bend therein; and means for guiding said hook in a rectilinear path parallel to said mandrel axis selectively to and from a position wherein the hook engages the tube at said portion rearwardly of the bend-start point.

12. The tube bender means of claim 10 further including means for biasing said hook to the tube-engaging position.

15. The tube bender means of claim 10 including means fo resiliently positioning said hook.

16. The tube bender means of claim 10 including means permitting limited pivotal movement of the hook about an axis parallel to said mandrel axis.

17. The tube bender of claim 1 wherein said hook defines a sharp rearward edge engaging the tube in the tube-holding disposition.

18. The tube bender means of claim 10 wherein said hook defines a sharp rearward edge engaging the tube in the tube-holding disposition.