GB2073279A

GB2073279A - Wall ties and methods of manufacturing wall ties

Info

Publication number: GB2073279A
Application number: GB8108592A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-03-19
Filing date: 1981-03-19
Publication date: 1981-10-14
Also published as: IE49200B1; IE792053L

Abstract

Each end of a wall tie (3) comprises a flat finger of material provided with one or more holes (4). In use, mortar flows into the holes (4) thereby anchoring the tie (3) in position. The tie (3) may also comprise a vertical twist (5) to prevent moisture flow along the tie (3) and a pin or stud to retain insulating material against a leaf of a cavity wall. In the method, a coil of mild steel is mounted on a decoiler, its free end is fed by a pneumatic feed, whose stroke is equal to the length of a wall tie, to a straightener and then to a press containing a die set which operates to pierce the holes in the metal and to subsequently guillotine the metal into lengths. <IMAGE>

Description

SPECIFICATION Wall ties and methods of manufacturing wall ties The present invention relates to wall ties and to methods of manufacturing wall ties.

Wall ties are devices which are used to hold in spaced apart relationship the two leaves of a cavity wall. Each end of the wall tie is embedded in a bed joint in a leaf of the cavity wall and the wall tie serves to hold the two leaves in that relationship.

A large number of different types of wall tie is known. One conventional wall tie comprises a strip of metal having bifurcated ends. Wall ties having bifurcated ends have been found to be particularly successful in that the ends of the tie are anchored firmly in the bed joints. However, the manufacture of metal wall ties having bifurcated ends requires manual methods or involves considerable wastage of metal.

The invention provides a method of manufacturing metal wall ties comprising the following steps: (a) performing a pressing operation at periodic intervals along a length of metal; and (b) cutting the metal into strips of predetermined size, each end of each strip being adapted, as a result of the pressing operation at step (a), to be anchored in mortar.

Advantageously, the pressing operation at step (a) comprises a punching operation.

The invention also provides a wall tie each end of which comprises a flat finger of material provided with one or more holes.

The invention will now be described more particularly with reference to the accompanying drawings. In the drawings: Figure 1 is a plan view of a wall tie in the position which it would occupy when located between the two leaves of a cavity wall; and Figure 2 is a side view of the wall tie shown in Figure 1.

The method of manufacture will now be described. A coil of mild steel is mounted upon a decoiler and the free end of the coil is passed through a straightener to a pneumatic feed unit which is capable of drawing the steel from the coil through the straightener. The stroke of the pneumatic feed unit is equal to the length of wall tie 3. From the feed unit the continuous strip passes into a crank operated press containing a die set. The pneumatic feed is activated during every up-stroke of the ram of the press.

The die set used to form wall tie 3 is provided with three distinct forming stations, each of which performs a forming operation on every downstroke of the ram. The first station is provided with six punches which pierce a row of six holes simultaneously.

The second station consists of a punch and die each of which is provided with a roller, the rollers being mutually offset by a distance equal to the radius of a roller plus the thickness of the strip metal. When the die set is fully closed the punch roller lies below the die roller. The arrangement of the second station provides for a twisting operation to be executed. The face of each roller is radiused so as to reduce drag during the forming operation.

The third station is provided with a cutting tool which cuts the strip metal into equal lengths, each length forming a wall tie. The cutting tool cuts the strip metal between the third and fourth holes of the row of six holes.

It will be appreciated that the method outlined above is carried out in an automated manner. In addition, the periodic times of the press and cutting tool and the speed of uncoiling are so arranged that substantially all of the metal from the coil of metal is utilized, the only wastage being the metal discs pierced from the strip to produce the circular holes.

The wall ties 3 are then zinc galvanized to inhibit the formation of rust. Galvanising takes place immediately after the metal has been cut into wall ties 3, and every surface of the wall ties 3 (including the freshly cut surfaces) is galvanized.

In a modification (not shown) of the wall tie of Figures 1 and 2, which enables the tie to be used to assist in holding insulating material in place against a leaf of a cavity wall, a relatively shorter half twist may be provided, located nearer one end of the tie and the tie may be provided with a hole about halfway along its length for receiving a pin by means of which the insulating material may be held against the leaf. Alternatively, during the method outlined above, studs may be studwelded onto the strip metal before it is cut into lengths.

Referring to the drawings, the wall tie 3 comprises a flat strip of galvanized mild steel, about 200 mm in length, 20 mm in width and 3.2 mm in thickness. The wall tie 3 conforms to the dimensions shown in British Standard Specification No. 1243: 1978 "Metal Ties for Cavity Wall Construction" (see Figure 3 thereof, which shows vertical twist wall ties fabricated from strip). Three circular holes 4 approximately 12 mm in diameter are provided at each end of the wall tie 3. The centres of the holes 4 are 18 mm apart.

A vertical twist 5 is provided midway along the length of the wall tie 3 to prevent moisture travelling along the surface of the wall tie 3 from the outer leaf to the inner leaf of the cavity wall (not shown).

When the wall tie is in position in a wall it is embedded in mortar. The latter passes through the holes 4 and thereby secures the wall tie 3 in position. The anchorage strength has been found to be comparable to that provided by traditional wall ties having bifurcated ends and has also been found to meet the requirements of British Standard No. 5080: Part 1:1974, "Methods of Test for Structural Fixings in Concrete and Masonry: Tensile Loading".

1. A method of manufacturing metal wall ties comprising the following steps:

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Wall ties and methods of manufacturing wall ties The present invention relates to wall ties and to methods of manufacturing wall ties. Wall ties are devices which are used to hold in spaced apart relationship the two leaves of a cavity wall. Each end of the wall tie is embedded in a bed joint in a leaf of the cavity wall and the wall tie serves to hold the two leaves in that relationship. A large number of different types of wall tie is known. One conventional wall tie comprises a strip of metal having bifurcated ends. Wall ties having bifurcated ends have been found to be particularly successful in that the ends of the tie are anchored firmly in the bed joints. However, the manufacture of metal wall ties having bifurcated ends requires manual methods or involves considerable wastage of metal. The invention provides a method of manufacturing metal wall ties comprising the following steps: (a) performing a pressing operation at periodic intervals along a length of metal; and (b) cutting the metal into strips of predetermined size, each end of each strip being adapted, as a result of the pressing operation at step (a), to be anchored in mortar. Advantageously, the pressing operation at step (a) comprises a punching operation. The invention also provides a wall tie each end of which comprises a flat finger of material provided with one or more holes. The invention will now be described more particularly with reference to the accompanying drawings. In the drawings: Figure 1 is a plan view of a wall tie in the position which it would occupy when located between the two leaves of a cavity wall; and Figure 2 is a side view of the wall tie shown in Figure 1. The method of manufacture will now be described. A coil of mild steel is mounted upon a decoiler and the free end of the coil is passed through a straightener to a pneumatic feed unit which is capable of drawing the steel from the coil through the straightener. The stroke of the pneumatic feed unit is equal to the length of wall tie 3. From the feed unit the continuous strip passes into a crank operated press containing a die set. The pneumatic feed is activated during every up-stroke of the ram of the press. The die set used to form wall tie 3 is provided with three distinct forming stations, each of which performs a forming operation on every downstroke of the ram. The first station is provided with six punches which pierce a row of six holes simultaneously. The second station consists of a punch and die each of which is provided with a roller, the rollers being mutually offset by a distance equal to the radius of a roller plus the thickness of the strip metal. When the die set is fully closed the punch roller lies below the die roller. The arrangement of the second station provides for a twisting operation to be executed. The face of each roller is radiused so as to reduce drag during the forming operation. The third station is provided with a cutting tool which cuts the strip metal into equal lengths, each length forming a wall tie. The cutting tool cuts the strip metal between the third and fourth holes of the row of six holes. It will be appreciated that the method outlined above is carried out in an automated manner. In addition, the periodic times of the press and cutting tool and the speed of uncoiling are so arranged that substantially all of the metal from the coil of metal is utilized, the only wastage being the metal discs pierced from the strip to produce the circular holes. The wall ties 3 are then zinc galvanized to inhibit the formation of rust. Galvanising takes place immediately after the metal has been cut into wall ties 3, and every surface of the wall ties 3 (including the freshly cut surfaces) is galvanized. In a modification (not shown) of the wall tie of Figures 1 and 2, which enables the tie to be used to assist in holding insulating material in place against a leaf of a cavity wall, a relatively shorter half twist may be provided, located nearer one end of the tie and the tie may be provided with a hole about halfway along its length for receiving a pin by means of which the insulating material may be held against the leaf. Alternatively, during the method outlined above, studs may be studwelded onto the strip metal before it is cut into lengths. Referring to the drawings, the wall tie 3 comprises a flat strip of galvanized mild steel, about 200 mm in length, 20 mm in width and 3.2 mm in thickness. The wall tie 3 conforms to the dimensions shown in British Standard Specification No. 1243: 1978 "Metal Ties for Cavity Wall Construction" (see Figure 3 thereof, which shows vertical twist wall ties fabricated from strip). Three circular holes 4 approximately 12 mm in diameter are provided at each end of the wall tie 3. The centres of the holes 4 are 18 mm apart. A vertical twist 5 is provided midway along the length of the wall tie 3 to prevent moisture travelling along the surface of the wall tie 3 from the outer leaf to the inner leaf of the cavity wall (not shown). When the wall tie is in position in a wall it is embedded in mortar. The latter passes through the holes 4 and thereby secures the wall tie 3 in position. The anchorage strength has been found to be comparable to that provided by traditional wall ties having bifurcated ends and has also been found to meet the requirements of British Standard No. 5080: Part 1:1974, "Methods of Test for Structural Fixings in Concrete and Masonry: Tensile Loading". CLAIMS

1. A method of manufacturing metal wall ties comprising the following steps: (a) performing a pressing operation at periodic intervals along a length of metal; and (b) cutting the metal into strips of predetermined size, each end of each strip being adapted, as a result of the pressing operation at step (a), to be anchored in mortar.

2. A method according to claim 1 in which the pressing operation at step (a) comprises a punching operation.

3. A method according to claim 2 in which each end of each wall tie is provided, as a result of the punching operation at step (a), with a series of holes disposed lengthwise along the wall tie.

4. A method according to claim 3 in which the series of holes so provided comprises three substantially circular holes.

5. A method according to any preceding claim, in which the metal is uncoiled from a coil of strip metal and then flattened before steps (a) and (b) are carried out.

6. A method according to claim 5, in which a further pressing operation is carried out which provides a twist at periodic intervals along the metal such that each wall tie cut at subsequent step (b) has a twist intermediate its ends.

7. A method according to claim 6 in which the twist so provided is relatively short lengthwise and is nearer one end of the wall tie.

8. A method according to any preceding claim, in which a punching operation is carried out so that each wall tie when formed has a pin receiving hole located approximately centrally thereon.

9. A method according to any of claims 1 to 7 in which a studwelding operation is carried out so that each wall tie when formed has a stud approximately centrally thereon.

1 0. A wall tie each end of which comprises a flat finger of material provided with one or more holes by means of which the wall tie can be anchored in mortar.

11. A wall tie according to claim 10, wherein each finger is provided with a series of three substantially circular holes, the series extending lengthwise along the tie.

12. A wall tie produced by a method according to any of claims 1 to 9.

13. A wall tie substantially as herein described with reference to and as shown in the accompanying drawings.

14. A method according to claim 1, substantially as herein described.