US3910092A

US3910092A - Metal expanding machine

Info

Publication number: US3910092A
Application number: US387703A
Authority: US
Inventors: Harold Rex Jury; Ronald Mckenzie Howells
Original assignee: Comalco J&S Pty Ltd
Current assignee: Comalco J&S Pty Ltd
Priority date: 1972-08-24
Filing date: 1973-08-13
Publication date: 1975-10-07
Anticipated expiration: 1992-10-07
Also published as: AU5891473A; OA04476A; DE2341886A1; IT992980B; ES418021A1; HK29878A; BE803964A; FR2196863A1; AU475675B2; GB1400137A; IN142123B; NL7311440A; NL170816B; CA975618A; AR197254A1; NL170816C; ZA735445B; FR2196863B1; BR7306425D0; PH9517A

Abstract

A metal expanding machine for expanding of a workpiece of metal having rows of overlapping slots, the machine having workpiece tool supports thereon each carrying tools for securing a workpiece, and at least one of the tool supports being controlled by fluid actuated cylinders and so arranged that it is driven away from the other by means of the cylinders but at the end of its outward movement the cylinders are reversed to move a tool support back by an amount sufficient to relax the workpiece so that it can be readily removed from the tools.

Description

[4 Oct. 7, 1975 1 METAL EXPANDING MACHINE [75] Inventors: Harold Rex Jury, Norwood; Ronald McKenzie Howells, Yennora, both of Australia [73] Assignee: Comalco (J. & S.) Pty. Limited,

Australia [22] Filed: Aug. 13, 1973 [21] Appl. No.: 387,703

[30] Foreign Application Priority Data Seifried 72/30 Kurtak 72/302 3,070,147 12/1962 Schalich 72/26 3,109,350 11/1963 Wilson 29/6.l 3,339,594 9/1967 Elliott 72/302 3,403,542 10/1968 BOVa 77/302 3,550,420 12/1970 Swanson 72/296 3,774,274 11/1973 Jury 29/6.l

Primary Examiner-C. W. Lanham Assistant Examiner-M. J. Keenan Attorney, Agent, or Firm-Jay L. Chaskin, Esq.

[57] ABSTRACT A metal expanding machine for expanding of a workpiece of metal having rows of overlapping slots, the machine having workpiece tool supports thereon each carrying tools for securing a workpiece, and at least one of the tool supports being controlled by fluid actuated cylinders and so arranged that it is driven away from the other by means of the cylinders but at the end of its outward movement the cylinders are reversed to move a tool support back by an amount sufficient to relax the workpiece so that it can be readily removed from the tools.

15 Claims, 14 Drawing Figures U.S. Patent Oct. 7,1975 Sheet 1 of 7 3,910,092

US. Patent 0a. 7,1975 Sheet 2 of7 3,910,092

U.S. Patent Oct. 7,1975 Sheet 3 of7 3,910,092

I U.S. Patent Oct. 7,1975 Sheet4 0f7 3,910,092

US. Patent Oct. 7,1975 Sheet 5 of 7 3,910,092

U.S. Patent Oct. 7,1975 Sheet 6 of? 3,910,092

US. Patent Oct. 7,1975 Sheet 7 of7 3,910,092

METAL EXPANDING MACHINE This invention relates to a metal expanding machine which is useful for the expansion of metal which contains slots between adjacent beads so as to form a truss like member, or an expanded mesh.

BACKGROUND OF THE INVENTION Proposals have been put forward heretofore for the formation of expanded metal wherein a strip of metal of constant thickness is sheared to have a series of rows of slits, the slits of any one row being staggered with respect to those of the next adjacent row, and the metal edges are then drawn apart so as to bend the metal between adjacent slits, tilt them with respect to the plane of the metal before bending, and form a mesh like panel. Such a panel has certain limited applications, but is not suitable for use as a load bearing member primarily because of the high stress concentrations at the ends of the slits and secondly because of the bending and displacement of the metal between adjacent slits.

This problem has been recognised and a number of proposals have been made to provide a member which is suitable, for example, for use as a load bearing member. Thus for example in the U.S. Pat. No. 1,510,702 issued to Rendleman, a truss like metal beam was formed by firstly forming slits between beads and then stretching those beads by passing the section longitudinally over gradually diverging guides. Rendleman also teaches that a subsequent rolling operation may be employed if this is desired. In the US. Pat. Nos. 1,510,697; 1,472,770; 1,472,771; and 1,472,772, H. M. Naugle et al teach various methods of expanding a slit metal member, all of which incorporate either the use of rollers or of heat, and in some instances reference is made to the distortion of the beads in a plane at right angles to the vertical plane of the product so as to obtain a preliminary stretching of the beads.

The US. Pat. No. 2,010,670 issued to Keller also refers to the production of an openwork structure from a member wherein a web has a series of rows of staggered slits, but this also employs the conventional expanding guide. Again, the US. Pat. No. 1,927,442 issued to Charles W. Laufle teaches the use of a wedge die which closely embraces both the web and flanges causing the flanges to be separated.

While prior art means and methods have been suitable for very large production of one size of open web structure, they have been quite unsuitable for general purpose work, and the tooling cost is prohibitive when small production runs of different configurations are required from a single machine.

MAIN OBJECTS OF THE INVENTION A main object of this invention is to provide a machine which is universal in its application for the expansion of slotted metal members, so that it can be quickly and easily adjusted from one configuration of expansion to another. A second object is to avoid the need for expanding rollers to providea satisfactory product, and a still further object is to provide a machine which can be quickly and easily loaded with a workpiece, which will then expand the workpiece, and allow ready removal of the expanded workpiece.

BRIEF SUMMARY OF THE INVENTION Briefly the invention consists of an expanding machine having a frame with longitudinal members and bearers which extend transversely, and which carry a tool support coupled to the frame by power actuated means, there being provided control members which are actuated by abutment members carried on the movable tool support and arranged so that the power actuated means when actuated will firstly move one tool support away from the other in transverse direction, thereby stretching a workpiece when secured to tools on the tool supports, but after the stretching has been completed, the power actuated means reverse so that one tool support is then moved inwardly towards the other, until a further abutment member carried by the tool support controls the power actuated means (after initial inward movement of the tool support) and tenninates actuation of the power actuated means so that the workpiece is relaxed in its tools and can be readily removed therefrom. This then enables a workpiece to be quickly and easily loaded into the machine and quickly and easily removed therefrom. Conveniently the degree of expansion can be adjusted by threaded members, although of course the first adjustable abutment member which effects reversal of actuation of the cylinders also functions as a means which limits the expansion of a workpiece.

A machine constructed according to the invention can be utilised for different configurations and diiferent degrees of expansion with relatively simple tooling changeover and adjustment.

The invention also includes a method wherein a workpiece is firstly expanded, and is then relaxed before it is removed from the tools which secure its edges.

More specifically a machine according to the inven tion may be defined as a metal expanding machine which comprises a frame having a longitudinal member and bearers extending tranversely thereof, a pair of spaced parallel workpiece tool supports supported by the bearers and extending in a longitudinal direction, workpiece engaging tools carried by respective said tool supports and arranged to engage the longitudinal edge portions of a workpiece having a web between the edge portions and a series of rows of slots in the web, the slots of each row being staggered with respect to and overlapping the slots of at least one adjacent row, power actuated means operatively coupling the tool supports and arranged upon actuation to increase the transverse distance between the tool supports thereby expanding a workpiece when its longitudinal edge portions are engaged by the tools, comprising a first abutment member and a first control member operatively coupled to said power actuated means, one of the members being secured to the frame and the other secured to the tool support and respectively positioned so that at the end of said movement which increases the transverse distance between the tool supports said power actuating means is reversed to reduce said transverse distance, and a second abutment member cooperable with a second control member respectively positioned so that after sufficient reverse movement to relax tension in said expanded workpiece said expanded workpiece said reverse movement is terminated.

The method of expanding a workpiece comprises having a pair of spaced parallel edge portions, a web between the edge portions, a series of rows of slots in the web, the slots of each row being staggered with respect to and overlapping the slots of at least one adjacent row, comprising securing the parallel edge portions to tools carried on respective workpiece tool supports driving the tool supports away from one another to separate the edge portions and stretch those portions of the web between said staggered adjacent slots, driving the tool supports towards one another by an amount sufficient to relax the stretched web portions,

and removing the expanded workpiece from the tools.

When a workpiece incorporates a series of rows of staggered slots, and is expanded by deforming so that the web portions between the edge portions of the workpiece are stretched, the ends of the intermediate portions of the web which are not directly connected to the edge portions are not subjected to strain as the edge portions are separated, and therefore the ends of the workpiece after stretching include short lengths which are not of the same configuration as the intermediate portion of the stretched member. To avoid discarding these irregular end pieces, it is necessary to impart a stretching to the intermediate web portions, but it is found that constraining them against longitudinal inward movement (as the edge portions are moved apart transversely) is completely unsatisfactory in most instances, and greatly limits the expansion of the workpiece.

Further, according to this invention, a metal expanding machine is provided with respective workpiece clamps at each end of the frame, further pressure fluid actuated cylinders on the frame having their piston rods respectively coupled to said further workpiece clamps for effecting movement of those further clamps in a longitudinal direction, and further control valves having conduit means coupling them to said further pressure fluid actuated cylinders. This then enables the further workpiece clamps to be clamped to the intermediate portions of a workpiece, and for those intermediate portions to be stretched in a longitudinal direction after the main stretch jaws have been relaxed in a transverse direction to release the stress in the web.

This procedure is effective in achieving a consistent pattern over the entire workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS of FIG. 1,

FIG. 3 is an end-elevational section taken on line 33 of FIG. 1,

FIG. 4 is also an end elevational section but taken on line 44 of FIG. 1,

FIG. 5 is a plan view of a workpiece before stretching, showing the edge portions, the web portions, and a series of rows of staggered overlapping slots which divide the web portion into a series of stretchable portions,

FIG. 6 is a section taken on line 66 of FIG. 5,

FIG. 7 is a plan view which corresponds to FIG. 5 but showing the workpiece after it has been stretched,

FIG. 8 is a section taken on line 88 of FIG. 7 but showing in addition to the workpiece, also the tools and tool supports utilised in the stretching thereof,

FIG. 9 is a section taken online 99 of FIG. I which illustrates the end clamps utilised for the secondary or longitudinal stretching of the workpiece,

FIG. 10 is a fragmentary plan showing a mesh type workpiece wherein the web portions are more bent than stretched during the expansion of the workpiece, FIG. 11 is a section on line l11l of FIG. 10 but drawn to an enlarged scale,

FIG. 12 is an enlarged plan view illustrating the tool location after expanding of the workpiece illustrated in FIG. 10,

FIG. 13 is a fragmentary perspective illustrating locating means for the locating of the tools shown in FIGS. 10, 11, and 12 before expansion of the workpiece, and

FIG. 14 is a diagrammatic representation of the hydraulic and electrical control means for the machine.

In general, a metal expanding machine 20 comprises a frame 21 (shown in FIGS. 1, 2, 3 and 4) which has a single longitudinal member 22 of I section, and bearers 23 which extend transversely of the longitudinal member 22.

Workpiece tool supports 26 are carried by the bearers 23, resting upon them, and these are coupled to the frame 21 by a plurality of pressure fluid actuated cylinders 27. It will be noted that in the embodiment described both workpiece tool supports 26 are arranged to be moved over the bearers, but it will be clear to those in the art that in many instances only one need be movable, and one of the workpiece tool supports can be fixed to the frame 20. The means which couple the cylinders 27 to the frame 20 comprise trunnion blocks 28 described hereunder in further detail, and which enable limited relative pivotal movement of the cylinders 27 to take place.

The valve means are not illustrated in the physical drawings of FIGS. 1, 2, 3 or 4, but are shown diagrammatically in FIG. 14 as a single valve 30 (in practice use may be made of more than one valve) the single valve 30 being a solenoid operated valve and being connected by pressure fluid conduits 31 to the cylinders 27 so that operation of the valve 30 will effect actuation of the cylinders 27.

The frame 21 has secured to it valve control means, a first valve control means being a limit switch 33, attached to a transverse bearer 23, (shown in FIGS. 1 and 14) which is operated by an adjustable abutment member 34 carried on an arm 35 on the workpiece tool support 26, and a second valve control means comprises a second limit switch 37, also attached to transverse bearer 23, which is functional to reverse operation of the valve 30. This is actuated by a second adjustable abutment member 38 also carried on the arm 35, the abutment member 38 having on it a swinging arm 39 arranged so that the second limit switch 37 is actuated only upon reversal of movement (that is in an inward direction) of the workpiece tool support 26. The valve 30 is further controlled by hand operated valve control means in the form of the two push button switches designated 41 and 42 in FIG. 14 (but not shown elsewhere), and it will be seen from FIG. 14 that one of these switches is effective in causing continued inward actuation of the cylinders 27, actuation of which had previously been arrested by the limit switch 37. Operation of the second button 42 will be seen to initiate the outward stroke of the respective cylinders 27.

After a workpiece has been expanded, it will be noted that the ends of some of the web portions not directly connected with the edge portions have not been themselves stretched (see FIG. 7) and to avoid wastage of material it is desirable to separately stretch those intermediate portions. To this end, the machine is pro vided with workpiece end clamps designated 45, these being under the control of further pressure fluid actuated cylinders designated 46 and referred to as end stretch cylinders, the cylinders 46 being trunnion mounted on brackets 47 which extend outwardly from the frame 21 at respective ends. These are controlled by further control valves (not herein illustrated) which may be hand operated or electrically operated but are continuously under operator control. No automatic termination of actuation of the cylinders 46 is incorporated in this embodiment, although if desired the automatic control of the cylinders 27 may be duplicated for this purpose. I

The above description is a description of the main elements of the invention, but the embodiment is de' scribed hereunder in further detail as follows:

Each of the cylinders 27 is trunnion mounted in a trunnion mount block designated 28 in FIGS. 1 and 3, the trunnion block 28 also having trunnion mounted therein a threaded rod 49 which carries on it two pairs of nuts 50, the arrangement being such that the nuts 50 abut the respective trunnion blocks 28 at the inner or outer end of stroke of the respective cylinders 27. This provides a positive termination of stroke, and the adjustable abutment member 34 is so adjusted that reversal of the valve 30 does not take place until the termination of stroke as fixed by the nuts 50. There are occasions when it is desirable for the workpiece to be stretched so that the final product has tapered sides instead of parallel sides, and this can be readily achieved with the arrangement described herein by mere adjustment of the nuts 50 since both the cylinders 27 and the threaded rods 29 are trunnion mounted and are pivotally mounted onto respective brackets 51 on the workpiece support 26. 1

FIGS. 5, 6, 7 and 8 illustrate workpieces before and after expansion effected by stretching. In FIGS. 5 and 6 an extrusion of an aluminium alloy (or other ductile extrusile material) designated 54 is provided with edge flanges 55, and a web 56 extending between them. The web is itself formed to have three beads 57, and the web is separately pierced to have a series of rows of slots 58 (four rows being shown) the slots of each row being staggered with respect to and overlapping the slots of each adjacent row. (In some cases, the rows are divided into pairs of rows of adjacent slots wherein the slots are staggered, but the adjacent rows of adjacent pairs have the slots in transverse alignment).

FIG. 8 illustrates how the workpiece is clamped between tools designated 61 which are carried on respective workpiece tool supports 26. The lower of the tool supports 26 is coupled directly to the piston rods of the cylinders 27 through the brackets 51 as described above, but the upper tool supports 26 are pivoted on pivot pins 62 (see particularly FIGS. 3 and 4), and are arranged to be lifted upwardly and outwardly from the lower tool supports 26 by means of tool clamp cylinders 63, pivotally attached to the lower tool support 26 and coupled to the upper tool supports 26 by means of lever arm 64 and coupling links 65.

In order to limit distortion of the flanges 55 of the workpiece 54, it is desirable that these flanges be clamped in place, so that use is made (in addition to the tool clamp cylinder 63) of back clamp cylinders 68. One back clamp cylinder is trunnion mounted to each of the tool supports 26, and the clamping of the flanges is effected by longitudinally movable clamp bars 69 which are coupled to the lower of the tool supports 26 by a plurality of short swinging links designated 70, each link 70 being pivoted at one end to a tool support and at the other to a clamp bar. This arrangement then provides means for quickly loading and unloading the workpiece, and clamping the workpiece flanges. The control means for the cylinders are their respective valves 73 (for cylinder 63) and 74 (for cylinder 68), these valves being solenoid operated valves. The valve 74 is controlled inter alia by :a limit switch designated 75 (shown only in FIG. 14), the limit switch 75 being co-operable to reverse the valve 74 when the workpiece is to be loaded or unloaded. This then is a standard cam operated limit switch butfor simplicity of illustration this has not been shown in FIG. 1. The cylinders 63 are either hand operated by a means of the switch designated 76, or alternatively timer operated by means of the timer designated 77. The function of the timer is described hereunder with respect to the stretching of mesh material.

Referring further to FIG. 14., an electric motor designated is mechanically coupled to two pumps, the pump designated 81 feeding the main stretching cylinders 27, the pump designated 82 feeding only the clamping

cylinders

63 and 68. In both cases there is an overload valve (both being designated 84) to protect the equipment against over pressure. (In practice there are two other tandem pumps, effecting independent control of the stretch cylinders, clamp cylinder 68, and end stretch cylinders. For the sake of simplicity these are not illustrated.)

A reference to FIG. 7 will illustrate how the intermediate beads which are designated 87 and which are not directly connected to the edge flanges 55 are not stretched as the other beads are stretched upon separation of the edge flanges 55, and to effect the required stretch the workpiece end clamps 45 are utilised. In FIG. 7 there are two only intermediate beads 87, and these are joined with a web portion 56 as shown. In FIG. 1 a more complicated arrangement is shown whereby it is necessary to elongate four pairs of intermediate beads 87 (not shown), and this is achieved by means of the end clamps 45 operated by the end stretch cylinders 46. The end stretch cylinders 46 are trunnion mounted so that normally they do not constitute an obstruction to the loading of workpieces in the machine. However they may be swivelled upwardly so that the wedge clamp members 89 (FIG. 9) lie in the same plane as the intermediate beads to be stretched, whereupon the cylinder 46 may be actuated to move the wedge clamps inwardly and over the beads to be stretched. Each pair of wedge clamps 89 is carried in a clamping block 90, and the clamping blocks are interconnected by means of toggle links 91, the toggle links being themselves connected to adjustable mounting blocks 92 by means of tension bars 93, and the arrangement is such that as the tension bars 93 are drawn rearwardly, the toggle links 91 become co-linear, and are retained in their co-linear positions by means of abutment extensions designated 94 which interengage one another. This then correctly positions the pairs of beads 87 (which otherwise tend to be too close to one another). The gaps between the respective beads are engaged by the pins 96 (FIG. 9) to further effect the accurate location of the pairs of beads. The mounting blocks 92 are adjustably positioned in a cross-bar 97, by means of bolts 98 the heads of which lie in a T slot 99.

The wedge clamp members 89 are urged against ramp faces in a clamping block 90 by springs 102, but these springs may be compressed and the blocks 89 urged into engagement with the end of a workpiece by operation of a release handle 103, each handle rocking about a pin 104, and having a finger 105 thereon which abuts the ends of blocks 89. Release of handle 103 allows the springs to expand and cause the space between the blocks 89 to increase. During the application of longitudinal stretch by cylinders 46, blocks 89 tend to move along the ramp face towards one another and thereby more firmly grip the workpiece. This is best illustrated in FIG. 9.

The FIGS. 10, 11, 12 and 13 illustrate the means and method by which the machine is used for expanding material to a mesh shape, wherein the beads or web portions 57 are bent rather than stretched. Bending (without appreciable stretching) can take place only if the length of the mesh panel is allowed to contract as the width increases, and this is effected by securing to the lower workpiece tool support 26 a track designated 110 containing a slot 111 which guides and supports rollers 112 on carriage blocks 113, each carriage block 113 having clamped to it a support hook 114 which engages the edge of a mesh panel (that is portion of the bead 57) as shown in FIG. 11. There are a series of carriage blocks 113 arranged in line in each of the tracks, and the centre carriage block is fixed. the others being movable with respect to that carriage block. They are interconnected by a flexible line designated 116, which when stretched taut maintains them in an equally spaced position. To accurately fix those positions, the upper of the two workpiece tool supports 26 is provided with an outstanding cam plate 117 as illustrated in FIG. 13, and recesses 118 in the cam plate 117 engage over respective carriage blocks 113 so that the surfaces of recesses 118 form abutment surfaces which accurately position them, this enabling the workpiece to be engaged on the hooks 114. To ensure that the final product has a consistent pattern throughout its entire area, the blocks 113 are formed of such length that they abut one another at the termination of formation of the panel from the workpiece. As the books 114 move towards one another, the flexible line 116 flexes illustrated in FIG. 12.

The following is a summary of the sequence of operations when a workpiece is to be expanded by stretching (FIGS. 1 through to 9):

A. All pumps idling, sliding clampjaws at their innermost position with clamp jaws open and back-up clamp released.

B. Slotted section loaded either from the end or above.

C. Clamp jaws and back-up clamp close by manual switching.

D. Stretch cycle initiated. Stretch cycle completed. Jaws relaxed so that no stress is left on the section being processed. All valves are centred so that the main stretch cylinders are locked at this point.

E. End stretch mechanism operated and detached.

F. Strain released from main stretch cylinders (by manual switching).

G. Back-up clamp and clamp jaws released (by manual switching).

H. Stretched product unloaded.

1. Machine reset.

The following summary is a sequence of operations when the workpiece is to be expanded by bending (FIGS. 10 through to 13):

Machine changed from a stretching to a bending cycle by a resetting selector switch (not shown herein).

A. All pumps idling. Section engaging hooks positioned and retained by location plate 118.

B. Preslotted extrusion placed on hooks.

C. Bending cycle initiated. Timer delays main stretch cylinders until location plate 118 has retracted, then bending cycle carried out to the released position.

D. Mesh unloaded.

E. Hooks reset by manual switching of top jaw and location plate 118.

F. Machine reset.

What we claim is:

1. A metal expanding machine for the expanding of a workpiece having spaced parallel edge portions, comprising:

a frame having a longitudinal member and bearers extending transversely thereof,

a pair of spaced parallel workpiece tool supports supported by the bearers and extending in a longitudinal direction,

workpiece engaging tools carried by respective said tool supports and arranged to engage the longitudinal edge portions of a workpiece having a web between the edge portions and a series of rows of slots in the web, the slots of each row being staggered with respect to and overlapping the slots of at least one adjacent row,

power actuated means operatively coupling the tool supports and arranged upon actuation to increase the transverse distance between the tool supports thereby expanding a workpiece when its longitudinaledge portions are engaged by the tools, comprising a first abutment member and a first control member operatively coupled to said power actuated means, one of the members being secured to the frame and the other secured to the tool support and respectively positioned so that at the end of said movement which increases the transverse distance between the tool supports said power actuating means is reversed to reduce said transverse distance, and

a second abutment member co-operable with a second control member respectively positioned so that after sufficient said reverse movement to relax tension in said expanded workpiece said reverse movement is terminated.

2. A metal expanding means according to claim 1 wherein said power actuated means operatively coupling the tool supports comprise a plurality of pressure fluid actuated cylinders, a solenoid operated valve having three positions, and arranged so that upon energizing one of two solenoids the cylinders are actuated to move the tool support outwardly; upon energizing the other solenoid the cylinders are actuated to move the tool support inwardly; and upon deenergising both solenoids the cylinders become inactive,

said first and second valve control members comprising respective limit switches secured to the frame, and operatively coupled to respective said solenoids, said adjustable abutment members being limit switch operating pawls.

3. A metal expanding means according to claim 1 wherein each said workpiece tool support is a movable tool support, and wherein there are two rows of said cylinders, each tool support comprising a horizontally movable portion fixed to the piston rods of a respective said row of cylinders and a pivoted portion, pivot means coupling the pivoted portion to the horizontally movable portion, and further comprising clamping tools secured to respective tool support portions of each tool support, further pressure fluid actuated cylinders constituting tool clamp cylinders and operatively coupling the horizontally movable and pivoted portions of each tool support for the effecting of clamping of the workpiece edge portions between respective pairs of said tools.

4. A metal expanding means according to claim 1 further comprising a pair of clamp bars, a series of swinging links coupling each clamp bar to a respective said workpiece tool support for effecting movement of the clamp bars in a horizontal plane. and respective further pressure fluid actuated cylinders operatively coupling the clamp bars to the respective workpiece for effecting movement of the clamp bars from outer positions inwardly towards the tools on the respective workpiece.

5. A metal expanding means according to claim 1 comprising a further pair of workpiece end clamps positioned one at each end of the frame, and further pressure fluid actuated cylinders constituting end stretch cylinders operatively cotp ling the workpiece end clamps to respective ends of the frame.

6. A metal expanding means according to claim wherein each said end stretch cylinder has a trunnion mounting joining it to the respective said end of the frame.

7. A metal expanding means according to claim 5 wherein each said workpiece end clamp comprises a pair of wedge clamp members slidable in a clamping block, and arranged to engage converging surfaces in the clamping block to thereby cause the wedge clamp members to firmly grip a workpiece with which they are engaged upon movement of the mounting block.

8. A metal expanding means according to claim 3 further comprising a pair of tracks, means securing the tracks to respective said horizontally movable portions of the tool support, a series of carriage blocks, rollers on each said carriage block engaging surfaces in a said track, a flexible line interconnecting the carriage blocks carried by each respective said track, and an inwardly directed workpiece engaging hook on each said carriage block.

9. A metal expanding means according to claim 5 further comprising a cam plate on the pivoted portion of each said respective tool support, each cam plate having a series of abutment surfaces each being arranged to position a respective hook and being so positioned that pivotal movement of the cam plate when effected by operation of said tool clamp cylinders positions said carriage blocks in an equally spaced relationship from one another.

10. A metal expanding means according to claim 5 wherein each said workpiece end clamp comprises a pair of wedge clamp members slidable in a mounting block, and arranged to engage outwardly converging surfaces in .the mounting block to thereby cause the wedge clamp members to firmly grip a workpiece with which they are engaged upon outward movement of the mounting block, and further comprising a series of toggle links interconnecting the workpiece end clamps at each end of the frame, a cross bar secured to the piston rod of each respective each said end stretch cylinder and tension bars joining respective said mounting blocks at each end of the frame to a said cross bar.

11. A metal expanding means according to claim 3 further comprising a pair of tracks, means securing the tracks to respective said horizontally movable portions of the tool support, a series of carriage blocks, rollers on each said carriage block engaging surfaces in a said track, a flexible line interconnecting the carriage blocks carried by each respective said track, and an inwardly directed workpiece engaging hook on each said carriage block, and wherein the lengths of the carriage blocks are equal, and also equal the pitch of a workpiece after it is expanded, the carriage blocks being positionable in end to end abutment.

12. A metal expanding means according to claim 5 further comprising a cam plate on the pivoted portion of each said respective tool support, each cam plate having a series of tapered mouth recesses each being of size to accommodate a respective hook between its side edges and being so positioned that downward pivotal movement of the cam plate when effected by operation of said tool clamp cylinders positions said carriage blocks in an equally spaced relationship from one another, a further solenoid operated valve, further pressure fluid conduits coupling said further valve to said tool clamp cylinders, a hand control switch and a timer control switch both interconnected with said further solenoid operated valve and arranged to independently complete an energising circuit therefor.

13. A method of expanding a workpiece having a pair of spaced parallel edge portions, a web between the edge portions, a series of rows of slots in the web, the slots of each row being staggered with respect to and overlapping the slots of at least one adjacent row, comprising,

securing the parallel edge portions to tools carried on respective workpiece tool supports;

driving the tool supports away from one another to separate the edge portions and stretch those portions of the web between said staggered adjacent slots;

driving the tool supports towards one another by an amount sufficient to relax the stretched web portions;

engaging the ends of said web portions with wedge clamp members;

applying fluid at pressure to cylinders coupled to said wedge clamp members to thereby actuate those cylinders and in turn elongate said web portions. releasing the wedge clamp members from the workpiece;

and then removing said workpiece from the tools.

14. A method according to claim 13 wherein said securing of the elongate portions of the workpiece to respective said tools comprises clamping said edge portions between the tools, and said deforming of the web portions comprises stretching and bending of the web portions.

15. A method according to claim 13 wherein said se curing of the edge portions of the workpiece to respecare movable along a track, moving said tool supports away from one another to thereby bend said portions and simultaneously move the carriageblocks towards one another, and then effecting said relaxing and retive said tools comprises positioning edges of the workmoving of the workpiece from the tools.

piece over hooks on respective carriage blocks which

Claims

1. A metal expanding machine for the expanding of a workpiece having spaced parallel edge portions, comprising: a frame having a longitudinal member and bearers extending transversely thereof, a pair of spaced parallel workpiece tool supports supported by the bearers and extending in a longitudinal direction, workpiece engaging tools carried by respective said tool supports and arranged to engage the longitudinal edge portions of a workpiece having a web between the edge portions and a series of rows of slots in the web, the slots of each row being staggered with respect to and overlapping the slots of at least one adjacent row, power actuated means operatively coupling the tool supports and arranged upon actuation to increase the transverse distance between the tool supports thereby expanding a workpiece when its longitudinal edge portions are engaged by the tools, comprising a first abutment member and a first control member operatively coupled to said power actuated means, one of the members being secured to the frame and the other secured to the tool support and respectively positioned so that at the end of said movement which increases the transverse distance between the tool supports said power actuating means is reversed to reduce said transverse distance, and a second abutment member co-operable with a second control member respectively positioned so that after sufficient said reverse movement to relax tension in said expanded workpiece said reverse movement is terminated.

2. A metal expanding means according to claim 1 wherein said power actuated means operatively coupling the tool supports comprise a plurality of pressure fluid actuated cylinders, a solenoid operated valve having three positions, and arranged so that upon energizing one of two solenoids the cylinders are actuated to move the tool support outwardly; upon energizing the other solenoid the cylinders are actuated to move the tool support inwardly; and upon deenergising both solenoids the cylinders become inactive, said first and second valve control members comprising respective limit switches secured to the frame, and operatively coupled to respective said solenoids, said adjustable abutment members being liMit switch operating pawls.

4. A metal expanding means according to claim 1 further comprising a pair of clamp bars, a series of swinging links coupling each clamp bar to a respective said workpiece tool support for effecting movement of the clamp bars in a horizontal plane, and respective further pressure fluid actuated cylinders operatively coupling the clamp bars to the respective workpiece for effecting movement of the clamp bars from outer positions inwardly towards the tools on the respective workpiece.

5. A metal expanding means according to claim 1 comprising a further pair of workpiece end clamps positioned one at each end of the frame, and further pressure fluid actuated cylinders constituting end stretch cylinders operatively coupling the workpiece end clamps to respective ends of the frame.

6. A metal expanding means according to claim 5 wherein each said end stretch cylinder has a trunnion mounting joining it to the respective said end of the frame.

10. A metal expanding means according to claim 5 wherein each said workpiece end clamp comprises a pair of wedge clamp members slidable in a mounting block, and arranged to engage outwardly converging surfaces in the mounting block to thereby cause the wedge clamp members to firmly grip a workpiece with which they are engaged upon outward movement of the mounting block, and further comprising a series of toggle links interconnecting the workpiece end clamps at each end of the frame, a cross bar secured to the piston rod of each respective each said end stretch cylinder and tension bars joining respective said mounting blocks at each end of the frame to a said cross bar.

13. A method of expanding a workpiece having a pair of spaced parallel edge portions, a web between the edge portions, a series of rows of slots in the web, the slots of each row being staggered with respect to and overlapping the slots of at least one adjacent row, comprising, securing the parallel edge portions to tools carried on respective workpiece tool supports; driving the tool supports away from one another to separate the edge portions and stretch those portions of the web between said staggered adjacent slots; driving the tool supports towards one another by an amount sufficient to relax the stretched web portions; engaging the ends of said web portions with wedge clamp members; applying fluid at pressure to cylinders coupled to said wedge clamp members to thereby actuate those cylinders and in turn elongate said web portions, releasing the wedge clamp members from the workpiece; and then removing said workpiece from the tools.

15. A method according to claim 13 wherein said securing of the edge portions of the workpiece to respective said tools comprises positioning edges of the workpiece over hooks on respective carriage blocks which are movable along a track, moving said tool supports away from one another to thereby bend said portions and simultaneously move the carriage blocks towards one another, and then effecting said relaxing and removing of the workpiece from the tools.