GB2033448A - Wall tie supporting insulation in cavity wall - Google Patents

Abstract

A wall tie for interconnecting the two leaves (7, 8) of a cavity wall and holding sheets (14, 15) of insulation material against one leaf of the wall consists of a strip (1) having a rod (5) extending through a hole in a centre region thereof and projecting equally from the opposed surfaces of the strip. The strip and rod are galvanised together. The wall tie is manufactured by feeding a sheet (Fig. 9) of steel having a width equal to the desired length of the wall ties intermittently past a series of tools (33, 34, 35, 56, 41, 43a, 43b, 48, 49, 52, 53) operated by a press (Fig. 6) in steps equal to the desired width of the wall ties, and closing the press after each forward movement to cause the tools to make a hole (108) and cuts (109, 110, 111, 114) and kinks (117, 118) in the sheet, and to sever successive strip portions in the shape of wall ties from the leading edge of the sheet. A rod (5) is then inserted through hole (108) and the strip and rod are then galvanized. <IMAGE>

Description

SPECIFICATION Improvements relating to wall ties The present invention relates to wall ties for interconnecting the leaves of a cavity wall.

More particularly, the invention relates to a wall tie which may also be adapted to support a sheet of foam plastics heat insulating material against the cavity face of the inner leaf of the cavity wall. In addition, the invention relates to a method and apparatus for forming wall ties.

British Patent Specification No. 1,486,170 describes a wall tie of plastics material comprising a central stem member having bifurcated ends and a plate or disc extending laterally from the central stem member and completely around it in a plane transverse to the axis of the central stem member. In use in a cavity wall construction, the plate or disc is intended to hold a sheet of insulation material in position against a leaf of the cavity wall internally of the cavity wall.

In practice, the manner of using such wall ties has been as follows: at or above the level of the damp-proof course, a row of wall ties is laid across the cavity in the conventional manner, with the locking plate spaced at a distance from the cavity face of the inner leaf of the wall equal to the thickness of the insulation material. The two leaves of the wall are then built up to a height equal to the height of the sheets of insulation material.

Sheets of insulation material are inserted into the cavity so as to rest on the wall ties between the locking plate and the inner leaf.

A second row of wall ties is then laid down in mortar on top of the two leaves of the wall, with the locking plate engaged against the top edge of the insulation material. Building of the walls is then continued and further sheets of insulation material are inserted into the cavity to rest on the second row of wall ties.

However there have been disadvantages in the use of such wall ties. Firstly, the locking plates do not extend sufficiently far in from the edge of the sheet of insulation material to hold the sheet reliably in position against the inner leaf. A gust of wind, for example, can dislodge a sheet from behind the locking plate. If only the tip of the locking plate engages the sheet, then the remainder of the locking plate is wasted. Secondly, the use of plastics wall ties does not meet approval by some of the authorities responsible for building work and the use of galvanised steel wall ties is preferred. However the manufacture of a steel wall tie with a locking plate completely around its stem would be very troublesome.

According to the present invention, a wall tie comprises a strip of rigid material adapted to interconnect two leaves of a wall having a cavity therebetween, and a rod extending transversely from at least one surface of the strip and intermediately of its ends, said rod being adapted to hold a sheet of insulating material in position in the cavity. Preferably the wall tie is of galvanised metal, particularly steel. Advantageously the rod may extend through a hole in the strip so as to extend an equal distance from opposed surfaces normally thereto. The rod may suitably be rigidly secured in the hole. The rod preferably extends perpendicular to the plane of the strip, so that when the wall tie is laid horizontally across a cavity, the rod extends vertically. The rod suitably has a length in the range 6-9 cm but is preferably about 7.5 cm.

Advantageously the ends of the strip may be bifurcated, and the strip may have one or more twists or kinks therein in the portion of the strip which is to be located in the cavity of the walls to permit water to drip off the tie.

The wall tie in accordance with the present invention is particularly suited for manufacture by stamping. In one aspect therefore the present invention provides a process for the manufacture of wall ties which comprises feeding to a press a sheet of steel having a width (transverse to the direction of feeding) equal to the desired length of the wall ties, forwarding the sheet intermittently past a series of tools operated by the press, the distance moved by the sheet in each forward step being equal to the desired width of the wall ties, and ciosing the press after each forward movement to the tools to make cuts and kinks in the sheet, and to sever succes- sive strip portions from the leading edge of the sheet.In order to make wall ties in accordance with the present invention, one of the tools cuts a hole to receive a perpendicu- lar rod in a centre region of each wall tie.

More particularly, said tools perform the following operations on successive strip portions of the sheet at each forward step: (a) making three cuts transverse to the forwarding direction in aligned positions, two of said cuts being at opposite edges of the sheet and the third cut being in a centre region of the sheet, but leaving web portions of the sheet uncut between said third cut and the other two cuts, (b) applying pressure from opposite directions perpendicular to the sheet at two points displaced in the forwarding direction and aligned with the centre of said third cuts to twist the material of each strip portion between said third cuts, (c) making two short cuts transverse to the forwarding direction at opposite edges of the sheet and in aligned positions corresponding to the axial mid-line of a strip portion, and splaying the bifurcated ends of the strip portion thus formed, and (d) severing each strip portion from the sheet by cutting the web portions of the sheet material.

In addition, the process normally comprises, either before or after the severing of the strip portion, the step of inserting a rod through the hole to a distance such that equal lengths of the rod project on both sides of the strip portion.

The invention will now be more particularly described with reference to the accompanying drawings wherein: Figure 1 is a perspective view of a wall tie according to the invention; Figure 2 is a cross-section of a cavity wall showing the wall tie located therein; Figure 3 is a plan view of the lower die assembly in the apparatus for making wall ties according to the invention; Figure 4 is an underneath plan view of the intermediate die plate; Figure 5 is a horizontal cross-section on the line B-B in Fig. 6; Figure 6 is a vertical cross-section on the line C-C in Figs. 3, 4 and 5, but omitting secondary guide columns and spring devices; Figure 7 is a side elevation of a bifurcating tool; Figure 8 is an end elevation of the bifurcating tool of Fig. 7; Figure 9 shows a plan view of a portion of the sheet which has been acted upon by the press;; Figure 10 shows a side elevation of a wall tie produced according to the invention.

Referring to Fig. 1 of the drawings, a wall tie comprises a strip 1 of metal such as galvanised steel (mild steel coated with zinc) having bifurcated ends 2, 3. A kink 4, or alternatively a single twist (not shown), may be formed in the strip in order to allow water to drip off it. A rod 5 extends transversely relative to the axis of the strip and perpendicular to the plane of the strip through a hole in the strip intermediate the ends thereof. The rod is a push fit in the hole and is secured therein by the galvanising of the strip and rod together. The rod (or pin) is of rigid steel wire.

Referring now to Fig. 2 of the drawings, a cavity wall 6 comprises inner and outer leaves 7, 8, comprised of bricks 9, 10, 11, 1 2 secured together by a layer of mortar 1 3. The wall tie 1 has its bifurcated ends 2, 3 embedded in the mortar, and the kink 4 abuts the inner face of the outer leaf 8 of the wall.

Sheets 14, 1 5 of plastics heat-insulating material (e.g. expanded polystyrene) are placed against the face of the inner leaf 7 of the wall and are securely held against the face of the leaf by means of the rod 5. The edges of such sheets of insulating material normally have tongue and groove engagement and a recess is cut in the grooved edge to accommodate the wall tie. The position of the rod 5 on the strip 1 may be chosen to suit the thickness of the foam plastics sheet material used.

In a particular example of a wall tie according to the invention the wall tie may be about 10 inches (26 cm) long, i inch (2 cm) wide and 1/8 inch (3 mm) thick. The transverse rod may be about 3 inches (7.5 cm) long and be about 1/8 inch (3.5 mm) in diameter. The rod may be located 4+ inches (12 cm) from one end of the strip, and the kink located on the other side of the rod may extend 1 + inches (4 cm) therealong from the rod.

The wall tie of the above dimensions may be used for tying together the leaves of a wall having a cavity of about 3 or 4 inches (7 to 10 cm) wide and constructed of standard blocks or bricks 4+ inches (12 cm) wide. The plastics sheet material may be 1 + to 2 inches (4 to 5.5 cm) in thickness. The usual cavity is 9 cm nominal width and the usual polystyrene board is 4 cm thick.

Obviously, the dimensions of the wall tie may be increased in order that it may be used for tying the leaves of a wall constructed of blocks or bricks of greater width than 4+ inches (11 cm), or if it is desired to have a wider cavity in order that the thickness of the plastics sheet material may be increased.

Equally the dimensions of the wall tie may be reduced. For example, the wall tie may have a length in the range of 8 inches (20 cm) to 20 inches (51 cm).

A wall tie in accordance with the invention has the strength of a conventional wall tie combined with a locking rod for holding the insulating material in position. The wall tie is simple and economic to make since it is only necessary to make a hole of suitable diameter through the wall tie in an appropriate position and insert the rod through the hole. No welding is required. The rod may be rigid steel wire which is readily available from manufacturers of nails. By using a rod it is possible to have a locking member which engages the insulation material for a substantial distance inwardly from the edge of the insulation material.

One embodiment of a method and apparatus for making a wall tie will now be described by way of Example, with reference to Figs. 3-9 of the drawings.

In order to make ties having a length of 10 inches (25.4 cm), a sheet of steel (3 mm thick) is used having a width of 10 inches transverse to the direction of forwarding of the sheet. The sheet is fed to a press intermittently, the sheet moving forward by 22 mm at each forwarding step. The feeding may be carried out automatically or manually after each operation of the press. In the press, the sheet is subjected to a series of stamping operations as it moves forward. The press may suitably be a 50 ton brake press.

Mounted between the jaws of the press is the stamping apparatus which comprises upper and lower pressure plates, a top die from which various punches depend, and intermeidate plate through which the punches pass, and a lower die against which the sheet is stamped.

As shown in Figs. 3-6, the upper pressure plate21 and the lower pressure plate 22 are movable towards and away from each other, guided by principal columns 23 extending up from the lower pressure plate and slidable in sleeves 24 depending from the upper pressure plate. When the pressure plates are pressed towards each other (under the action of the press) the columns 23 slide up through apertures 25 in the upper pressure plate.

The top die 26, secured underneath the upper pressure plate 21, is movable towards and away from the intermediate plate 27, guided by secondary columns 28 which are indicated in Fig. 5 but omitted in the other Figures. The top die 26 and intermediate plate 27 are urged apart by springs (not shown) mounted around rods 29 (indicated in Fig. 5 only), the top of the springs being received in recesses 30 in the bottom surface ofthe top die.

Depending vertically from the top die are the following tools which are slidable through apertures in the intermediate plate as indicated: - a cylindrical punch 31 having an external diameter equal to the diameter of the pin 5, and located in a centre region of the die. This punch is slidable in aperture 32 in the intermidiate plate.

- three rectangular starting punches 33, 34, 35 aligned transversely across the die.

Two of the punches 33, 35 are located in opposite side regions of the die while the central punch 34 is located in the centre region of the die, having one of its ends aligned in the longitudinal direction with the cylindrical punch 31. There is a gap 36 of the order of 2.5 cm in distance between punches 33 and 34, and a gap 37 of the order of 5.4 cm in distance between punches 34 and 35; these punches 33, 34 and 35 are slidable in slots 38, 39 and 40 respectively in the intermediate plate.

- a cylindrical deforming tool 41, displaced in the longitudinal direction from the centre of central punch 34. The tool 41 has a rounded head (see Fig. 6) and is slidable in aperture 42 in the intermediate plate.

- two bifurcating punches 43aand 43b, located in opposite side regions of the die.

Bifurcation punch 43 is shown in Figs. 7 and 8: Each bifurcating punch has an inclined cutting edge 50' and the face of the cutting edge has a chamfer 33. The longer side of the punch is closer to the side of the die and the chamfer is on the downstream face of the punch. These punches are slidable in slots 44, 45 in the intermediate plate. Adjacent to these slots, on the upstream side thereof, the bottom surface of the intermediate plate has recesses 46, 47.

- two severing punches 48, 49 which are aligned in the longitudinal direction with thegaps 36, 37 between the punches 33, 34, 35. The severing punches are slidable in slots 51 in the intermediate plate.

- two splaying punches 52, 53 each having a chisel-shaped tip with the blade lying transversely. These punches are slidable in apertures 54 in the intermediate plate.

All of the punches are secured in the top die by Allen-type screws (not shown) accessible from the top of the upper pressure plate.

The lower die assembly comprises five die blocks 61, 62, 63, 64, 65 in a nest 55 and an ejector pad 66 which projects above the other die blocks. The sheet of steel is fed in direction A (the downstream direction) and the edges of the sheet are indicated by dotted lines 67, 68 in Fig. 3.

Between die blocks 61 and 62 there are three slots 69, 70, 71. These slots correspond to the position of the starting punches 33, 34, 35 in the top die 26.

In the centre region of the die block 61 is a round hole 72 which corresponds to cylindrical punch 31 in the top die. This punch cuts the hole to receive the pin in each wall tie.

The third die block 63 houses ejector pad 66 which moves up and down against spring loading. Near to the centre of ejector pad 66 there are two holes 73, 74 which are aligned in the fdrwarding direction. Hole 73 houses a cylindrical deforming tool 56 which projects upwardly through the ejector pad as the pad is pushed down. The deforming tool 56 has a rounded head and is received in aperture 56a in the intermediate plate. Hole 74 receives the corresponding cylindrical deforming tool 41 mounted on the top die. Holes 73, 74 are sijdEd'd apart in the forwarding direction with theirentres about 1 9 mm apart.

Ejector pad 66- is scooped out to form a recess 75'in its upper and forward faces.

The fourfh-dib block 64 has a central channel 76 cut down from its top face which continues the valley started by recess 75. The forward face of die block 64 has two recesses 77, 78 at its edges. Recesses 77, 78 correspond to the positions in the top die of the two bifurcating punches 43b, 43a.

Separated from the projecting centre por tion of die block 64 by a space 79 about - 4 inch (6.3 mm) across is a fifth die block 65.

The space 79 receives the two severing punches 48, 49 held in the top die, these punches being in line with the gaps between slots 9, 10 and 11.

The fifth die block 65 has a narrow flat top surface 80 and a downwardly sloping delivery surface 81, part of which is scooped out to form a recess 82 in line with channel 76.

Flanking the fifth die block 65 are two splaying blocks 83, 84 which are secured to the downstream face of the nest 55 by bolts (not shown). Each splaying block has a flat top surface 85 and a downwardly sloping front surface 86, at the junction of which t- tVU zist. kSc there is a hole 87 to receive one of the splaying punches 52; 53.

Each of the apertures 69, 70, 71, 72, 79 leads to an opening through the lower pressure plate 22, via which sheet material cut out by the punches is discharged.

Downstream of the fifth die block 65 and splaying block 83, 84, there is an opening 88 in the lower pressure plate, through which the wall ties drop after they have been formed.

Along each of the longitudinal edges of the lower die block assembly there are three cylindrical support bosses 88, 89, 90. The first of these bosses 88 on each side is surmounted by a narrow neck 98 and a cap 99 on top of the neck of about the same diameter as the cylinder. The other bosses just have a narrow neck 100 on top. The bosses are retractable into the die assembly against spring pressure.

When the steel sheet is fed into the press, it is located between the neck portions of the two leading bosses 88, resting on the shoulders of the respective bosses, and held below the cap on top of each neck. The sheet, as it progresses through the die, is guided between the neck portions of the bosses 89, 90, resting on the shoulders thereof.

Mounted on the lower pressure plate, downstream of the opening 88, there is a support 101 for an adjustable stop 102 which extends back over the opening 88. The stop 102 is screw threaded so that the amount by which it projects from support 101 can be adjusted.

The intermediate plate 27 moves downwardly away from the top die when the press is opened but is pressed against both the top die and the lower die assembly when the press is closed. On the lower face of the intermediate housing plate there are four.lo- cating pins 42 a and'42 b which are received in locating holes 103pin the ejector pad 66.

The locating pins are aligned in pairs, one pair being aligned longitudinally with the inner end part of slot 38 afld the other pair being aligned longitudinally with the inner end part of slot 40. Transversely, the pins are aligned in pairs just upstream and downstream of the apertures 42 and 56a. The bottom surface of the intermediate plate has six recesses 104 to receive the tops of the support bosses 88, 89, 90.

The intermediate plate also has a central channel 105 scooped out of its lower face in line with slot 39 and extending from aperture 42 to the downstream face of the plate.

The sheet of mild steel is fed to the press from a delivery device which can move up and down against spring loading so that the sheet can drop from its feeding level (indi cated by dotted lines 106 in Fig. 6) to be pressed against the lower die assembly. The sheet can conveniently be fed by hand, the extent of each feeding movement being deter mined by stop 102, which is at the feeding level of the sheet.

The process of forming a wall tie will now be described with reference to Fig. 9, as well as Figs. 3-8.

When the sheet 11 9 is fed as far as and just past slots 69, 70, 71, the press is closed by operation of a switch. The upper pressure plate 21 descends rapidly, pushing the intermediate plate 27 down on to the support bosses 88, 89, 90 and ejector pad 66, which retract into the lower die assembly. The sheet is pressed against the lower die face by the intermediate plate. As the upper pressure plate continues to travel downwards, the top die closes on the intermediate plate and the punches are pushed downwardly to act on the sheet.

A pin receiving hole 108 is cut by the cylindrical punch 31, and a row of slots 109, 110, 111 is cut by the starting punches 33, 34, 35. Slots 109 and 111 both extend to the side edges of the sheet while slot 110 is in the centre region of the sheet.

The press opens again, withdrawing the top die and intermediate plate upwards, and allowing the ejector pad and support bosses to resite, thus bringing the sheet material up from the lower die to the feeding level.

The sheet is then moved forward until the slots 109 and 111 are in position to engage locating pins 42a (this amounts to 22 mm forward movement). The press is closed again and another row of slots is cut in the sheet by punches 33, 34, 35. This cutting of slots by punches 33, 34, 35 is continued in sequence as the sheet moves forward.

Between each succeeding row of slots 109, 110, 111 is a strip portion having the dimensions of a wall tie, but the sheet is held together by web portions 112, 113 between the slots. The sheet is moved forward until the front row of slots is in position to be engaged by locating pins 42b by when the second row of slots is in position to be engaged by locating pins 42a. With each forward move, ment of the sheet the successive rows of slots are presented to these locating pins.

While held by the locating pins, the strip portions are acted upon by the deforming tools 41 and the deforming tools are located to act upon the edges of the strip portion at a point in line with slots 110. Because the slots 110 have been cut in the sheet, the edges of the strip portions are free to twist, up on one side and down on the other side, under the pressure of the counteracting deforming tools.

The downwardly kinked portion 117 is pushed down into recess 75 and in its subse quent forward movement it is received in channel 76 when the press is closed. Likewise the upwardly kinked portion 118 is received in channel 105 on the underside of the inter mediate plate.

When the sheet has been moved forward again, each strip portion is presented to the bifurcating punches 42, 43. As the bifurcating punches descend on the sheet, they cut a slot 114 at each end of the strip portion, on the axial mid-line of the strip portion. As the bifurcating punch moves downwards, it starts to splay the bifurcated ends 11 5, 11 6 of the strip portion into a fish-tail configuration and pushes the downstream end portions 11 6 downwards while the upstream end portions 115 tend to rise up into recesses 46, 47 in the intermediate plate.

Finally after another forward movement, the sheet reaches die block 65. The leading edge of the sheet buts against the stop 102. When the top die descends, the severing punches 48, 49 cut through the web portions 112, 11 3 holding the strip portion on to the remainder of the sheet. During the severing operation, the downwardly kinked portion is received in recess 82. At the same time, the chisel-ended splaying punches 51, 52 are pushed down into slits 114 to increase the splaying apart of the bifurcated ends. Because the splaying blocks 83, 84 have downwardly sloping front surfaces, the end portions 11 6 (which were pushed down by the bifurcating punches) are not pushed up again. The severed strip portion (see Fig. 9a) falls away down sloping delivery surface 26.

A pin 5 (e.g. a wire nail) is then pushed through the pin receiving hole 108 until it projects equally from each face of the wall tie.

The insertion of the pin may be integrated into the press closure operation, or it may be performed separately by holding the wall tie in a jig and hammering the pin through the hole until it comes against a plate below the jig.

It is an advantage of the present invention that the pin can be simply inserted into a hole which has been stamped out during the manufacture of the tie and no welding of the pin is necessary. The complete tie is then galvanised in accordance with British Standards 1243 and 729.

However, the apparatus of the present invention may be modified to make wall ties without the pin-receiving hole, if required.

It will be apparent from the accompanying drawings that the term "centre region" is not used in this specification to define the exact centre of a strip portion or die but rather to distinguish an area which is generally central in contrast to being at one edge of the strip portion or die.

Claims (23)

1. A wall tie comprising a strip of rigid material adapted to interconnect two leaves of a cavity wall and a rod extending transversely from at least one surface of the strip and intermediately of its end, the rod being adapted to hold a sheet of insulating material in position in the cavity.

2. A wall tie according to claim 1, wherein the rod extends from both opposed surfaces of the strip normally to said surfaces.

3. A wall tie according to either of the preceding claims wherein the rod extends through a hole in the strip.

4. A wall tie according to any of the preceding claims, wherein the rod extends an equal distance from opposed surfaces of the strip.

5. A wall tie according to claim 3, wherein the rod is rigidly secured in the hole.

6. A wall tie according to any of the preceding claims, wherein the strip and rod are of galvanised metal.

7. A wall tie according to claim 6, wherein the rod is secured in the strip by galvanising of the strip and rod together.

8. A wall tie according to claim 4, wherein the rod has a length in the range 6-9 cm.

9. A wall tie according to claim 8, wherein the rod is approximately 3 inches (7.5 cm) long.

10. A wall tie substantially as described herein with reference to Figs 1, 2 and 10 of the drawings.

11. A process for the manufacture of wall ties which comprises feeding to a press a sheet of steel having a width (transverse to the direction of feeding) equal to the desired length of the wall ties, forwarding the sheet intermittently past a series of tools operated by the press, the distance moved by the sheet in each forward step being equal to the desired width of the wall ties, and closing the press after each forward movement to cause the tools to make cuts and kinks in the sheet, and to sever successive strip portions from the leading edge of the sheet.

1 2. A process according to claim 11 wherein one of the tools cuts a hole perpendicularly through the sheet material to receive a rod in a centre region of each strip portion.

1 3. A process according to either of claims 11 and 12, wherein one of the tools repeatedly cuts a slot in a centre region of the sheet and two other tools apply pressure from opposite directions perpendicular to the sheet to twist the sheet material between said slots.

14. A process according to either of claims 11 and 12, wherein the following operations are performed on successive strip portions of the sheet at each forward step: (a) making three cuts transverse to the forwarding direction in aligned positions, two of said cuts being at opposite edges of the sheet and the third cut being in a centre region of the sheet, but leaving web portions of the sheet uncut between said third cut and the other two cuts, (b) applying pressure from opposite directions perpendicular to the sheet at two points displaced in the forwarding direction and aligned with the centre of said third cuts to twist the material of each strip portion be tween said third cuts, (c)- making two -short cuts transverse to the forwarding direction at opposite edges of the sheet and in aligned positions corresponding to the axial mid-line of a strip portion, and splaying the bifurcated ends of the strip portion thus formed, and (d) severing each strip portion from the sheet by cutting the web portions of the sheet material.

1 5. A process according to claim 1 2 which comprises additionally inserting a rod through the hole to a distance such that equal lengths of the rod project from both faces of the strip portion.

16. A process for the manufacture of wall ties according to claim 11, substantially as described hereiri with reference to the drawings.

17. A wall tie manufactured by a process according to any of claims 11-16.

1 8. Apparatus for the manufacture of wall ties comprising tipper and lower dies adapted to be moved repeatedly towards and away from each other by a press and means to guide a metal sheet during forwarding movement of the sheet between the dies, said guide means being spaced apart on opposite sides of the lower die by a distance equal to the desired length of the wall ties, said upper die having tools depending therefrom and receivable in corresponding apertures in the lower die, said tools including a rectangular centre punch which is in a central region between said guide means with the long side of the rectangle transverse to the forwarding direction of the sheet, rectangular edge punches parallel to said centre punch and located to intersect the edge lines of the sheet defined by the guide means so as to cut edge slots in from both side edges of the sheet, said edge punches being spaced from said centre punch in a transverse direction, a cylindrical deforming tool aligned in the forwarding direction with the centre of said rectangular punch, chamfered blades to cut slits between said edge slots and to splay portions of the sheet material between said slits and adjacent edge slots, and severing punches located to be aligned in the forwarding direction with spaces between the centre punch and edge punches, said cylindrical deforming tool depending from the upper die being matched by a deforming tool projecting from the lower die and offset thereto in the forwarding direction by a distance corresponding generally to the width of a wall tie to be produced, so that said deforming tools act on the sheet from opposite directions.

1 9. Apparatus according to claim 18, wherein one of the tools is a cylindrical punch located in a centre region between the guide means and having a small diameter to cut a hole to receive a rod therethrough.

20. Apparatus according to claim 1 8 or 19, wherein an intermediate plate is provided between the upper die and lower die and the tools pass through apertures in said intermediate plate.

21. Apparatus according to claim 20, wherein the intermediate plate carries locating means adapted to engage slots cut in the sheet material so that the sheet material is located and held in the desired position relative to the deforming tools.

22. Apparatus according to either of claims 20 and 21, wherein the lower die and intermediate plate have channels to accommodate kinks in the sheet material produced by the deforming tools.

23. Apparatus for the manufacture of wall ties substantially as described herein with reference to Figs. 3-9 of the drawings.