US3068782A

US3068782A - Apparatus for bending a flexible metal wire or strip

Info

Publication number: US3068782A
Application number: US25632A
Authority: US
Inventors: Hasenfratz Willi
Original assignee: FORSCHUNGS ANSTALT fur MECHANIK
Current assignee: FORSCHUNGS ANSTALT fur MECHANIK
Priority date: 1959-12-21
Filing date: 1960-04-29
Publication date: 1962-12-18
Anticipated expiration: 1979-12-18

Description

Dec. 18, 1962 w. HASENFRATZ APPARATUS FOR BENDING A FLEXIBLE METAL WIRE OR STRIP Filed April 29, 1960 nu 4 LQI /NVENTOR-' MLLI HGSE v ByZl/tam,

A it orneys -linearly extending guide channels.

United States atent 3,008,782 Patented Dec. '18, 1962 [ice 3,068,7 82 APPARATUS FOR BENDING A FLEXIBLE METAL WIRE R STRIP Willi Hasenfratz, Benken, Switzerland, assignor to Forschungs Anstalt fur Mechanik, Vaduz, Liechtenstein, an establishment of Liechtenstein Filed Apr. 29, 1960, Ser. No. 25,632 Claims priority, application Germany Dec. 21, 1959 6 Claims. (Cl. 100-26) This invention relates to an apparatus for bending flexible metal rods in the form of wire or strip.

It is known to bend a flexible metal rod in the form of wire or strip by inserting the rod axially into a guide channel with a contour corresponding to the desired form of bending. For removing the bent wire, there is provided a lateral gap which opens into the guide channel throughout the length thereof. In some constructions, this gap or slot is also open during the bending operation; consequently, the guide means for the rod are not closed on all sides, so that in some circumstances the rod can extend through the gap while it is being guided through the guide channel so that the desired bending is not effected. However, even when the bending operation takes place satisfactorily, it is possible for the bent rod subsequently to issue prematurely through the gap or slot.

It is true that there are also known constructions in which the guide channel is closed laterally during the bending operation and is only opened for extracting the bent or curved rod. However, this is efiected by hinging the guide housing or by removing one side of the guide channel which is formed by parts of the housing wall. Both these arrangements can be used only with recti- Consequently, the guide channel is subdivided into a series of adjoining rectilinear partial channels which are disposed at a predetermined angle to one another and each partial guide channel must be separately opened and closed laterally. Apart from the complicated nature of this construction and the inconvenient manipulation required, the friction when pushing the rod through axially is impermissibly high.

An object of the present invention is to obviate these disadvantages of the known constructions. Accordingly, the invention provides a method of and apparatus for bending a flexible metal rod in wire or strip form by axial insertion into a guide channel having a path corresponding to the desired form of bending, from which channel it is removed in the bent or curved state through a lateral gap or slot opening into the guide channel throughout its length. The method of invention is characterised by the fact that at least three juxtaposed flexible tubes are so arranged to conform to the desired bending path that they enclose between them a longitudinally extending cavity and also have, at the most, a mutual spacing from one another which is less than the thickness of the rod to be bent, the rod being pushed axially through the cavity between the tubes and forming the guide channel and at least one tube being thereafter displaced laterally relatively to the other tubes to such an extent that a gap exceeding the thickness of the rod is formed between two tubes, the bent rod being removed laterally through this gap. The apparatus of the invention comprises at least three juxtaposed flexible tubes which between them define the cavity and guide components for holding these tubes in an arrangement corresponding to the predetermined bending path, at least one guiding component being so adjustable that, in one position, all tubes are positively held at a mutual spacing less than the thickness of the rod to be bent and the central cavity enclosed by the tubes forms a guide channel for the rod, whereas in another position of the said guiding component, a gap of an internal width exceeding the thickness of the rod and extending throughout the length of the channel is formed between at least two tubes. The flexible tubes have the advantage that they are adapted in the continous path to any desired form of bending, and in addition offer a minimum resistance to the flexible rod being pushed through the cavity between the tubes, because the rod does not bear on guiding surfaces over its entire length, but only at individual punctiform positions or short lines. The invention is especially suitable for forming loops or the like for banding pack ages, the flexible rod consisting of metal bands or of metal wires of circular, elliptical, oval or other cross-section, such as are usual in this field. Flexible rods of this type are more especially used on wire-banding or strip-banding machines, in which the loop or the like is generally formed by direct mechanical looping around the package. However, the nature of the packages is not always suitable in order to serve at the same time as a bend former for the looping of the wire. Moreover, it is necessary for the package, on forming the loop, to be already in the position inside the machine which is necessary for the banding operation, whereas with the arrangement according to the present invention, the loop or the like can be produced independently of the package and the extraction of the loop from the guide channel, which takes only a short time, can be effected immediately as soon as the package has assumed the desired position so that it is possible to produce a more rapid completion of the entire banding operation and thus a more rapid flow of the successive packages.

In the accompanying drawings:

FIG. 1 is a perspective view of an apparatus according to the invention, in an open position, I

FIG. 2 is an end view of the left-hand end of a housing of the apparatus in the closed position,

FIG. 3 is a view similar to FIG. 1, but showing a second embodiment,

FIG. 4 is a cross-section to a larger scale,

FIG. 5 shows diagrammatically an example of use, and

F G. 6 is a plan view of a modification.

The construction illustrated in FIGS. 1 and .2, cornprises a housing 1 which is of arcuate form and has a continuous recess 2 the cross-section is shaped'as a T lying on its side. Arranged one above the. other in the portion 3 of the recess 2 are two flexible tubes'4 and 5, while a third flexible tube 7 is arranged in the stem 6 of the recess. The housing is subdivided symmetrically of the'stem 6 into two halves 8 and 9. The lower half 9 is split longitudinally into separate segments. 10, 11 and 12,which are independently adjustable with respect to the half 8 transversely of the stem 6. In the closed position (shown in FIG. 2) the half 9 is moved up to the half 8 by exerting vertical forces P on the

segments

10, 11 and 12 so that the three tubes 4, 5, 7 are positively held mutually abutting one against the other. In this position, a flexible rod 13 which is to be bent and has the form of a round wire can be pushed axially througha cavity 14 disposed between the tubes and serving as a guide channel. The tubes 4, 5, 7 preferably consist of helical springs of identical dimensions and having turns which bear positively one against the other, these turns being adapted continuously to the form or shape given by the recess in the housing 1. Nevertheless, the turns of the springs do not otter 'any considerable resistance to the movement of metal rod 13 between them since therod 13 has only punctiform bearing on the individual turns of the springs which are circular in cross-section; in addition, the turns of the springs automatically centre the rod 13 because of their cross-section so that the rod cannot deflect from the central direction and Cannot strike against surfaces extending transversely of the direction of displacement.

After the wire has been pushed completely through the cavity or guide channel 14, it is freed therefrom by openingthe housing, the half 9 being lowered into the open position shown in FIG. 1 by devices (not shown) and by converting the. compressive forces P into oppositely directed tensile forces. "The result of this movement is that a clearance exceeding'the thickness of the rod 13 is formed between the two tubes 4, located in the portion 3 of the recess 2. Consequently, the rod 13 can be removed 'betweenthe tube's4, 5 and the slot 16v which exists on the inside between the'halves 8, 9 by pulling the rod at its -two'ends. The slot on the outside has no influence on the extraction of the wire, since it is closed in the inward .direction by the tube 7. As can be seen from FIG. 2, the slot 15 exists. even when the housing isclosed. The internal width. of theslot 16 is somewhat greater than -that;of the slot 15. However, there is no objection to the slots '15 and 16 or only one of the slots being closed when the housing is closed. Nevertheless, it is advisible -if'ithereis some clearance between the housing halves 1, -9 when the; housing is closed, as this ensures that the tubes 4,5, 7 rest reliably one against the other and therefore that the guide channel 14 is closed around its length so that unintended-egress of the rod 13 is prevented.

a The construction illustrated inFIGS. 3 and 4 merely .difiers from the preceding construction by'the fact that .the recess 2 is shaped as an inverted T so that its stem 6 -and-the

slots

15, 16 are at right-angles to the plane formed 1 ,theaxis; ot-the guide channel 14, instead of being in this .actual plane as in FIGS. '1 and 2. An inner half 17 .oiitheghousing l is-a fixed element andan outer half 18 is, open and are .notable to-preventthe rod from falling out, perhaps dueto hearing one against the other, the tubes 5 .and 4 are. secured against lateral movement; as showni i-respect,oftheinner-half 17 according to FIG. 4, rhy, ,ai.deyice, th'eiorrn of .a countersunk, head rivet .23 nor the .like. I Thegshank of-v the ,rivet 23 canibe. pressed s lirc1y-iatoamrre pcn i s bo e 24 of the half- 17,

1 jF'lgrishowsb way ofexample;;the:useofthemethod iafth in cn i n or and ns-P ckas s y m ansarmetal iwigeqrstrip'. r-Fo'r thispurpo'se, :there is provided .a device J:|.'avin'g theionstrhction shdwnfin FIG. lfbllt with-a housgin 25.haying theshapeofaslotted, rectangular or square irm-g .udth rounded corners, .but, inv othehrespects coniqrniing withthehousing ofthe arrangement according to FIG... 1. Thus, the-housing '25; -is.subdivided intotwo halves and hasslots lying in .the plane ofthe axis of the jgufide. channel which isrepresentedby a chain-dotted line i ll ust ratingthefhent.or curved rod or wire. Apackage26 b; hande ispushed. c n ral y th u h t Slotted r n 'iQIEI' dbYthQ h m ina ihe naqk gc'li ured in the position desired for the banding operation. The hous- "jng 'ZS- is'thenyopened, as described in connection with FIG. 1, and-the

endportions

29 and 30 of the banding wire projectingfrom e'ndportions'2f7, 28 of the housing are :gripped n11echanically and tensioned in the direction not the arrows." Theiwire then emerges through the inner islotof the housing 25' and already has the form of a loop ;or the like, @By' further tensioning, this loop is'applied nightly argundtthe ackage 26; inrth'ev manner' usual with -wireebanding machines, whereupon the; ends of the wire ,.are twisted :and theexcess. portions are cut 911.. Another vLwireis. insertedaxially 1 0 the guide channel and can be bentor curved iorranothcr workingoperation with the housing closed and be brought into position ready for another banding operation.

Instead of a sharp bend, it is also possible to provide a rounded transition, as provided in the four corners in the housing 25 according to FIG. 5.

In the modification illustrated in FIG. 6, the two

end portions

27, 28 of the housing 25 are bent in opposite directions from the annular plane so as to avoid bending down the

end portions

29, 30 of the wire.

Where reference is made herein to the. thickness of the flexible rod 13, this is always to be understood to mean the largest transverse dimension of the actual rod profile in that direction which lies parallel to the internal width of the guide channel gap or slot when the rod is introduced into the channel and through which the bent or curved rod is moved out laterally from the guide.

Apparatus and mechanism capable of movingthe guide components are conventional, and have been known for some time, as for instance, shown in US. Patent No.

2,136,225, to W. E. Williams, which issued November 8,

1938, in which FIG. 13A and FIG. 13B disclose a two part. guide frame in which-the frame parts may be opened and closed by means of toothed racks 150, which cooperate with two gears 151. In this way, the two frame parts may be moved away from each other ortoward each other, in order to adjust the size of the opening for the strapping material. Also, U. S. Patent No. 2,908,215, in the nameof Paul W. Fawcett,-issued October 13,1959, which shows a guide channel in accordance with FIG. 6 of this patent, formed by a rigid part 23 and a movable ,part 30. FIGS. l7and 18 show the housing part 57, and the movable part 56, operable by means. of springs 59. FIGS.'-20, and 25 to. 28 also show twospart. guide means for use in Wire-tying machines.

The number of flexible .tubes is not restricted tothree.

I claim:

1. Apparatus for bending a flexible metal wire or strip comprising at least threejuxtaposed flexible tubes defining a cavity between them, a housing formed by guide components holding said tubes in the shape of a desired bending path whereby said cavity formsi-aguide channel forsaid wire, at least one of said components being movable'b'etween aposition in which all of said tubes are heldpositively at a mutual spacingless than 'theithicknes's of thewire-to be bent and a position in. which a gap of I an internal widthexceeding the thicknessof thesaidwire and 1 extending throughout the length-f of=;said channel is formed between at least two of said: tubes, saidaguide components forming the housing: having a: slotbetween twov components throughswhich the wire isiinsertetd and "withdrawn into and; out of the-apparatus.

2. Apparatus according to'claim 1, in which said flexible tubes are helical springs with juxtaposedturns.

3. Apparatus accordingto claim 1; in-Which there are .three tubes arranged in triangular position in crosssection.

4. Apparatus according to claim l,in which the housing has a recess therein which isv T-shaped' in crosssection, two of said tubes being arranged in one portion ofsaid recess and the third. tube being arranged in the stem thereof, said housing being provided in two halves which are movable relatively to one another transversely of the. stem so that they can be moved; apart from :a closed position in which they hold the three tubes mutually bearing one against the other to an open position in which said twotubes disposed in the one portion; of .sail recess have a spacing exceeding the thickness of the ro v --5. .Apparatus according toclaim Lin-which thehous- .inghasa recess therein which' i's T-shaped; in crosssection, two: of said tubes being arrangedin one portion .of said recess and the ,third tube being arranged in the stern .thereoflsaid housing being divided symmetrically -into twohalves which are adjustablerelatively to :one anotherv transversely of .the stemsqtha-t they can be if. v

moved apart from a closed position in which they hold the three tubes mutually bearing one against the other to an open position in which said two tubes disposed in the one portion of said recess have a spacing exceeding the thickness of the rod, and said two tubes arranged in said one portion being secured against transverse sliding movement relatively to the half of said housing accommodating them.

6. Apparatus according to claim 1, in which at least one half of said housing is divided into segments disposed longitudinally one behind the other, and transversely adjustable as such relatively to the other half of said housing.

References Cited in the file of this patent UNITED STATES PATENTS 2,356,904 Workman Aug. 29, 1944 2,853,938 Hall et a1 Sept. 30, 1958 FOREIGN PATENTS 804,226 Great Britain Nov. 12, 1958