US3352330A - Web bender for forming a continuous v-contoured web - Google Patents

Description

R. A. G. CAPE Nov. 14, 1967 WEB BENDER FOR FORMING A CONTINUOUS V-CONTOURED WEB Original Filed Jan. 17, 1961 INVENTOR R. A. G. CAPE BY fmlyz ATT RNEYS United States Patent ee 3,352,336 Patented Nev. 14, 1967 3,352,330 WEB BENDER FOR FORMING A CON- TINUUS V-CONTURED WEB Richard Allan Gordon Cape, Lachine, Quebec, Canada,

assignor to Dominion Bridge Company, Limited, Montx'eal, Quebec, Canada @riginal application lian. 17, 1961, Ser. No. 83,228, now Patent No. 3,158,731, dated Nov. 24, 1964. Divided and this application Nov. 20, 1964, Ser. No. 412,693

17 Claims. (Cl. 140-105) This invention relates to web benders used in the fabrication of light weight truss construction. This application is a division of my previous application, Ser. No. 83,228, filed Jan. 17, 1961 and now Patent No. 3,158,731.

Wood has been used for centuries as a construction material in the form of beams, studs, frames, etc. In more recent years, other materials have found favour by providing advantages not obtainable with wooden members. Development of metal substitutes was found to be practical and economical with the result that the substitutes have become primary construction items. Those which provide the combination of practicability and economy to the greatest degree are naturally more desirable and find greater acceptance in their sphere of use.

The web bender of this invention is similar in effect to a pair of mating gears, both having infinitely large radii between which thin materal is bent to form shapes approximately Warren type web configurations. In such a comparison, each gear is replaced by a stationary track which in plan may be considered to be straight on adjacent sides, straight or curved on the opposite sides and rounded at both ends. Around each track a series of joined links may be rotat.d. Each link contains a centrally located tongue (representing a gear tooth) which may move normal to the link in its centerline plane, but whose axial movements are controlled by bearing at its inner end against a cam within each track. The outer ends of the tongues contact the web material which b:nds reversely around each consecutive tongue when the links are in motion.

Rotary motion of the links around the tracks produce a continuous uninterrupted Warren type webmember for continuously made trusses.

The invention is illustrated by. ways of example in the accompanying drawings, in which:

FIG. 1 is a plan of the web bender.

FIG. 2 is a diagram of the track outline of the webV bender.

FIG. 3 is a diagram of a modified track outline of the web bender.

FIG. 4 is a diagram of a further modified track outline of the web bender.

Referring to the drawings, the web bender consists essentially of two chains of links 120 in which each link contains a tongue 121 which bears axially against a cam plate 123 located between each of two double tracks 124 which support the links. In addition, a driver sprocket 126 produces the required motion of the links and tongues for web forming.

The number of links 120 in each chain is not a fixed quantity. No fewer than 6 links however, can be used and no more than 10 are necessary. It is essential that the length of adjacent sides of the tracks be vtwo links in length. The opposite side of each track may be equal or shorter in length and the two curved ends may be of equal or different diameters. The periphery of the tracks is developed to allow the links to rotate freely and snugly.

The length of each link in a chain is equal to the panel spacing of the Warren web configuration of the nished truss, less an appropriate amount to allow for springback of the web wire after forming.

Each link in a chain, is essentially the same excepting possibly the ends where links are joined one to another. Each link may have male and/or female end configurations in order to join the links together into an endless chain.

The links consist of two side plates 130, 131 separated by means of a pair of fillers 132. At the middle of each link and between the two fillers, there is a space for a component tongue 121. This space also contains bearings or rollers 135 which accurately guide the component tongues and allow only an axial movement of the tongues. An additional space 137 between side plates also exists at each end of each link. This space permits the bending end of a tongue from the opposite chain of links to enter freely, so that the centre of the bending pin 138 of the tongue corresponds or neariy so, to the centre of the axle 139 joining the links together. It is obvious that the axles joining any two links together are not continuous through the side plates, but instead at each link junction there are two axles which are securely retained in the side plates of one link and pass through the other side plates of an adjoining link to allow pivoting of the links about the centre of the axles. These axles project beyond the outer surface of the links with provision for attachment of an outboard roller 140 to each separate ame. These rollers bear against grooves in the edges of the track 124 to permit rotation of the chain of links around the tracks. The rollers are in pairs at each axle centreline to procure stability against tilting and ensure that all movable parts rotate around the trackway in a common plane.

Additionally, each link contains two bending anvils 142 near each end located inwardly from the axles. Their function is to produce bending of the web wire 10` in close proximity to the bending pin 138 of each tongue of the opposing trackway, which enters into the space 137 between adjacent anvils and link side plates.

If the bending anvils were not used, it is possible to produce a Warren type web but the diagonals between the apex curves would not be straight. A non-uniform bend would occur in which the diagonal on one side of an apex was reasonably straight for aproximately half of its length while the diagonal on the other side of the apex would be curved. Curved diagonals would reduce compression capacity of the diagonals and increase the deflection of'the truss having'diagonals subject to tension loading.

The tongues 121 are uniform in outer contour and preferably either square or rectangular in cross-section, to assist in avoiding any rotary tendency of the tongue about their own longitudinal axes. The length of all tongues is uniform for any fixed web contour, but the length varies with the depth of the Warren type web configuration for any other web size.

Each tongue has a tongue `bending pin 13S about which the web is formed during bending `and a tongue cam roller 146 which in bearing against the cam 123 fixes the extent of axial movement of the tongues. In addition, light springs 147 may be used to assure that the tongue cam rollers are in contact with the cam as each tongue in turn enters into the space between the corresponding two links of the other trackway to avoid jamming under power.

In any uniformly bent Warren type web, the length of the web material along its centreline from the apex Of one bend to the apex of the next nearest bend must be constant. Similarly, the distance along the web centreline from the point of first contact of the tongue bending pin with the web to the corresponding point on the next nearest bend, must be the `same constant. Also, as the angle of bend of the web increases during bending, the first initial contact point between web and the tongue bending pin must be maintained without slipping. The locus of movement of the tongue bending pin 138 to accomplish this is predicated by the location and contour of the cam 123.

More specifically, the cam causes the device tooperate in the following manner:

(a) As the outer end of the tongue approaches the wire being drawn into the machine, the cam causes the tongue to extend longitudinally. At the instant of contact of web and tongue, the length of wire from point of contact to a similar point on the preceding tongue is the length required from the apex of one finished bend tothe ,next apex. This carefully determined length does not change during progress through the machine.

(b) After initial contact, the tongue starts to retract longitudinally as it moves into the machine while maintaining the initial point of contact between wire and tongue without change. This retraction continues until the tongue enters the space between the parallel sides of the track.

(c) During movement of the tongues through the parallel space between the two sets of tracks, the cam is parallel with the tracks. The tongues therefore do not move longitudinally. They maintain the initial points of wire-tongue contact during final forming.

(d) On exit from the space between the tracks, the tongues again retract to clear the bend in order to avoid unbending of the finished shape of the web.

The cam contour is determined by accurate layout and close machining tolerances. The location of the cam relative to the track contour must also be accurately positioned and maintained.

For convenience, the cam is placedcentrally between each pair of tracks -and lis thus central with the links and tongues. The tongues make contact with the cani through the medium of the tongue cam roller 146 which permits reduction of wear by rolling action, compared to sliding contact between tongue and cam.

Two sets of tracks 124 are essential and each set is composed of one or two tracks. Each set of tracks carries a similar set of links which rotate at similar speeds around the tracks, but the sets of links are angularly disposed, one with respect to the other by half a link length. The spacing between tracks must be accurately maintained for any fixed Warren web configuration. In practice, kthe distance between tracks 124 is made adjustable to permit bending of various depths of web. A change in web depth also requires a change` in tongue length rand a change in the anvils 142.

The double` track in each set isf-a convenience in supporting the links and tongues to assure the rotary motion in a common plane. Also the double track permits central location of the cam 123 in the plane of the centreline of tongues and links. Again, for convenience, the outer edges 149 of the tracks arenot flat, but are grooved to restrain the link rollers 140 from side movement to assure link rotation also ina common plane.

The contour of the bottoms of the grooves around the tracks again must be accurately determined and `machined to permit rotation of the links around the tracks without binding or without excessive looseness. Although the tracks appear in FIG. l to consist in plan of two half circles joined to a middle rectangle, purely circular ends will not allow rotation of the links except with excessive looseness. Thus in FIG. 1, if the ends were circular, the links could be made to fit snugly around the track as shown in the upper portion of the machine, but the links could then not be rotated, because of binding, to the position shown in the lower portion of the machine.

The track profile must be modified from purely circular ends as shown in FIG. 2. Here the left hand side is shown with a modification of both quadrants 151, 152 of the curved end, while in the right hand side, one quadrant 153 is shown circular, and the other quadrant 155 is shown modified. Either modifications are feasible for smooth angular rotation of thelinks around the tracks without looseness or binding. The more acceptable method however, it is shown in the right hand end of this view where the four quadrants 153 nearest adjacent tracks are circular. This then permits a more feasible draughting method of determining the locus of movement of the tongue bending pin from the point of first Contact between pin and web material to completion of each angular bend of the web.

In the two adjacenty set of tracks, as shown in FIG. 2, the length of the rectangle between end quadrants is equal to two link lenths. It is also quite feasible, or even desirable, to change -the profile of the tracks to that shown in FIG. 3. In this case the length of the straight portion of the adjacent track sides is maintained to two link lengths. However the remaining profile may be further altered, as shown in FIG. 4, to provide a small radius of curvature at the entry end to reduce the length of tongue extension and a large radius at the exit end to avoid overlap on tongue retraction. The remaining profile joining the two end curves may be straight or curved, provided that the links can be rotated to any position without binding or excessive looseness. In this development the sides of the two sets of tracks adjacent to one another are the at sides.

The rotation of the links and tongues around the tracks is most satisfactorily produced by reason of a torque load applied through -a shaft 157 to a sprocket 126 which drives against a pin 159 ylocated on each link of one chain of links.

The sprocket 126 is located for convenience on the under side of the middle cam 123 and between the double tracks 124. Teeth on the sprocket overlap the links and act against pins 159 fastened to each link of one of the chain of links to produce peripheral movement of the chain of links around the tracks.

It is unnecessary with this machine to drive both chains of links with separate sprocket drives. One driven set only will also drive the non-sprocketed chain by reason of the entry of tongues into corresponding Irecesses of the opposite chain of links.

No deformation of bends will take place when one chain of links only is driven.

Materials such as wire 10 drawn from a reel into the web bender will not issuesufiiciently straight to assure that the dagonals of the Warren type web are straight. For this reason, it is preferable to utilize a wire straightener 10a ahead ofthe web bender.

When :a tongue in motion first contacts the wire 10, it will instigate a bend at the proper point only if the wire is reasonably in line with the centreline of the web bender. At high forming speeds, the entering wire 10, if tree, could swing from side to side as each successive tongue made contact and instigate a reversing swing. The f bends would then be initiated at points slightly in error.

The wire straightener 10a of the web bender may be adjusted to create a slight tension to lavoid the wire swing from side to side and compel initial contact points to take -place close to the centreline of the machine and thus at theoretically correct locations for instigating the start of a bend.

The tension or load required to pull the wire 10 through the straightener 10a is supplied by the web bender, thus assuring exact synchronization of feed into and through the bender.

What I claim is:

1. A web bender for forming a continuous V-contoured web comprising means to feed a wire web into the said bender, two co-planar sets of web-engaging tongues, means defining a path foreach set along which the tongues of that set are movable from opposite sides into a Common Central zone, and means for advancing the said tongues within the said central zone from opposite sides and through the said zone, with the tongues of one set -alternating with the tongues of the other set and moving the V-contoured web out of the said zone, means f-or mounting the tongues of each set for longitudinal sliding movement transversely across the respective path of movement of the set in the said plane of the set.

2. A web bender as set forth in claim 1 including means associated with the said tongues for advancing the tongues into and through the said central zone.

3. A web bender as set forth in claim 1 in which the said tongues are kept in a constant endwise position through the said central zone.

4. A web bender as set forth in claim 1 in which is included two co-planar closed tracks with facing sides, a set of endlessly connected links mounted on each track, a web-engaging tongue mounted on each link, means to turn said links around said tracks in unison, with the said facing sides of the tracks defining the central zone wherein said tongues are advanced.

5. A we-b bender as set forth in claim 4 in which each of the said tongues includes -a carn follower bearing against a cam, the said cam having one side adjacent the said central zone straight and parallel to the facing sides of the said tracks.

6. A web bender -as set forth in claim 4 in which the said `co-planar tracks have straight facing sides and rounded ends and the said tongues are mounted perpendicular to the said links and are longitudinally slidable with respect to the said links.

7. A web bender for forming -a continuous V-contoured web comprising means for feeding a straight wire into the web bender, two co-planar closed tracks in said web bender, the said tracks having straight facing sides and rounded ends, a set of endlessly connected links riding each track, a web-engaging tongue mounted on each link perpendicular thereto and longitudinally slidable with respect to the link, means for turning said links around said tracks in unison, said facing sides of said tracks defining a central zone wherein said tongues are translated with the tongues of one set alternating with the tongues of the other set, a cam attached to the tracks and a cam follower on each tongue, the said cams having their sides adjacent the said central zone straight and parallel with said facing sides of said tracks.

8. A machine according to claim 7, where the said means for turning the said links around the said tracks includes a driven sprocket engaging the links of one of said sets of links.

9. A machine according -to claim 7, wherein said links support rollers riding said tracks, the said rollers being coaxial with the pivotal connections between said links.

10. A machine according to claim 7, wherein springs urge the said tongues with their cam followers into engagement with said cams.

11. A machine according to claim 7, wherein the said tracks on opposite sides of the centerline have remote quadrant corners which are non-circular, but which are profiled to permit freedom of rotation of the chain of links without binding.

12. A machine according to claim 7, wherein the said tracks have the remote sides thereof curved.

13. A machine according to claim 7, wherein a space is provided in said links at the pivotal connections between links, the tongues of one set of links extending into said space, and anvils being provided in said links on either side of said space, said anvils engaging diagonal portions of a web 4being formed to ensure straight diagonal sections between Iapices of the formed web to increase the compression and tension resistance of the web.

14. A web bender as claimed in claim 1 in which each set of tongues includes a cam surface against which the tongues react to etfect the said longitudinal movement, said cam including a rst surface portion contoured to cause the tongues to extend outwardly at the position whereat the tongues rst contact the incoming wire, the distance between said position and the point of Contact between the previous tongue and the wire being substantially equal to the length of wire required from apex to apex of the web.

15. A wed bender as claimed in claim 14 wherein the said cam further includes a second cam surface portion contiguous with said first cam surface portion and permitting the tongues to retract, as they move from initial contact to the said central zones at a rate which will ensure maintenance of the initial point of contact between the wire and the tongues.

16. A web `bender as claimed in claim 1S wherein the cam includes a third cam surface portion contiguous with said second portion and permitting said tongues to maintain -a constant longitudinal position during movement through the central zone.

17. A web bender as claimed in claim 16 wherein the cam includes a fourth cam surface portion contiguous with said third portion and permitting said tongues to retract when passing out from the central zone to clear the finished web to avoid unbending thereof.

References Cited UNITED STATES PATENTS 337,509 3/1886 Laskey. 1,293,295 2/1919 Amidon. 1,297,304 3/1919 Ford. 2,350,996 6/1944 Attsinson et al. 18--19 X 2,623,266 12/1952 Hemmi. 2,764,193 9/1956 Knowles. 3,077,000 Q/1963 Huisman et al. 18--19 3,102,776 9/1963 Steinmann et al 18-18 X 3,119,175 8/1965 Wogerfbauer 140--105 X WILLIAM I. STEPHENSON, Primary Examiner.

Claims (1)

1. A WEB BENDER FOR FORMING A CONTINUOUS V-CONTOURED WEB COMPRISING MEANS TO FEED A WIRE WEB INTO THE SAID BENDER, TWO CO-PLANAR SETS OF WEB-ENGAGING TONGUES, MEANS DEFINING A PATH FOR EACH SET ALONG WHICH THE TONGUES OF THAT SET ARE MOVABLE FROM OPPOSITE SIDES INTO A COMMON CENTRAL ZONE, AND MEANS FOR ADVANCING THE SAID TONGUES WITHIN THE SAID CENTRAL ZONE FROM OPPOSITE SIDES AND THROUGH THE SAID ZONE, WITH THE TONGUES OF ONE SET ALTERNATING WITH THE TONGUES OF THE OTHER SET AND MOVING THE V-CONTOURED WEB OUT OF THE SAID ZONE, MEANS FOR MOUNTING THE TONGUES OF EACH SET FOR LONGITUDINAL SLIDING MOVEMENT TRANSVERSELY ACROSS THE RESPECTIVE PATH OF MOVEMENT OF THE SET IN THE SAID PLANE OF THE SET.

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