GB2197890A

GB2197890A - Manufacture of arches

Info

Publication number: GB2197890A
Application number: GB8628394A
Authority: GB
Inventors: Stephen Mortimer
Original assignee: Ibstock Building Products Ltd
Current assignee: Ibstock Building Products Ltd
Priority date: 1986-11-27
Filing date: 1986-11-27
Publication date: 1988-06-02
Anticipated expiration: 2006-11-27
Also published as: GB2197890B; GB8628394D0

Abstract

The invention discloses a feature arch constructed from a row of blocks, a middle one 2 of which is in the shape of a trapezium and is flanked by two groups of voussoirs 4, 6 each having an exposed surface in the form of a parallelogram. Each group of voussoirs 4 is composed of blocks which are mirror-images of the voussoir blocks 6. A reinforcing rod or rods may be provided through bores (8 Fig. 3) in each block. A method of making these blocks 2, 4, 6 is described which uses angularly adjustable cutting wires (20 Fig. 4) to cut the blocks from a column of brick clay. The column is provided with a keyway (14 3) engaging with a key of the cutting table to prevent "wander". <IMAGE>

Description

Manufacture of arches.

The invention is concerned with improvements in or relating to the manufacture of arches, particularly but not exclusively, horizontal arches.

It is usual in the constructions of buildings to incorporate in their wall constructure immediately above a door or window aperture, a decorative feature replacing or concealing a lintel member. Such a feature may be constructed from contoured stone or other blocks for example bricks. It is usual in the latter case to manufacture specially shaped bricks for this purpose, which involves additional expense.

One form of arch which is often used is the flat or jack arch the bricks of which, while lying in a horizontal course parallel to the ordinary standard brick course, are each in the form of a trapezium. The angles of the trapezium-form bricks nearest the centre of the arch are o close to 90 , but differ more markedly from a right angle towards the ends of the arch. In terms of geometry, side surfaces of the bricks are formed on lines radiating from an imaginary point many feet below the arch. Such bricks are known as voussoirs. Since bricks are commonly made from an extruded column of brick clay, it has been the practice to make a special cutting box for each brick shape required. This is time-consuming and costly, since there is such variation in size and span of arches required that it is rare that a set of boxes can be used for more than one building job.

It is an object of the present invention to provide special bricks for incorporation into feature arches, which bricks are able to De manufactured at lesser additional cost.

The invention therefore provides a feature arch comprising a first clock of traezium-snape arranged between two groups of voussoirs to form an elongate series above a door or window aperture, a first of said groups of voussoirs comprising a row of Identical blocks having at least one exposed surface thereof in the form of a parallelogram other than a rectangle and a second of said groups of voussoirs comprising a row of identical blocks each block thereof being a nlirror-inlage of the corresponding block in said first group.

O o Preferably, the two angles, x and 180 - x , included in said parallelogram correspond to the angles included in the trapezium of said first block. This forms a horizontal or flat arch. Where the angles do not so correspond, the arch formed may be in the form of an inverted "V".

Conveniently in the case of a flat arch, bores may be formed in the voussoir blocks so as to communicate with a bore or bores in the trapezium-shaped block and with each other to form an elongate passage to receive reinforcing rods.

The invention further provides a method of producing voussoir blocks as described above including the steps of extruding a column of brick clay and subjecting it to a cutting operation wherein cutting strips are arranged at an oblique angle with respect to a centre line of the column.

Conveniently,said cutting strips may be adjustable between o o a cutting angle of x and an angle of 180 - x to produce voussoirs of said first group and said second group.

Advantageous said cutting strips comprise conventional cutting wires.

There will now be described with reference to the drawings and arch according to the invention. It will be understood that the description of the arch and of the method by which it is formed is given by way of example only and not by way of limitation.

In the drawings: Figure 1 shows a fragmentary view of a wall including blocks forming a flat arch; Figure 2 is a diagrammatic view of apparatus for cutting a column of brick clay in the method according to the invention; Figure 3 shows a cross section of the column taken on line III-III of Figure 2, to an enlarged scale; Figure 4 is a plan view of apparatus set to cut a first group of blocks; Figure 6 is a plan view of apparatus set up to cut a series of trapezium-shaped blocks.

Figure 7 is a section on line VII-VII of Figure 1.

A flat or jack arch is formed at a window aperture by a first block 2 having a trapezium shape flanked by two groups of blocks 4, 6 having an exposed surface in the shape of a parallelogram with an included acute angle of o 70 . Blocks 6 are mirror-images of blocks 4 and since the o o block 2 includes angles of 70 and 110 , the arrangement as shown forms a flat arch. Bores 8 (see Figures 3 and 7) are formed through the blocks to receive transverse rods (not shown) for reinforcement.

Figure 2 shows a conventional brick clay extruding auger barrel 10 from which is produced a column of clay 12 having a cross-section as shown in Figure 3. In addition to the bores 8, a keyway 14 is formed for reasons to be explained below.

Apparatus is also depicted in Figure 2 in side elevation which comprises a movable carriage 16 provided with a plurality of adjustable mounting devices 18 for a desired number of cutting wires 20, see Figures 4, 5 and 6. The column of clay 12 is forwarded on to a machine table of the apparatus by means of a conveyor 22 and is thence cut by the wires 20 in a conventional cutting operation.

However, in order to produce the voussoirs 4 and 6 and the trapezium shaped blocks 2, differing arrangements of the wires are required, which are illustrated in Figure 4, 5 and 6 respectively.

Referring to Figure 4, whereas it is conventional to arrange a wire perpendicular to the line of clay movement shown at arrow A, in order to produce voussoirs 4, the o wires are arranged at an angle of 70 at a spacing suitable to produce an end surface to each block 4 of y mm, equivalent to the end surface dimension of a conventional block (brick) 24 used in the surrounding structure of the arch.

When it is desired to produce voussoirs 6 of the opposite hand, then the position of the wires is reversed as in Figure 5. Figure 6 shows the wires arranged so as to produce the blocks 2, the smaller end surfaces of which also have the dimension y mm.

Because of the oblique alignment of the wires there is the possibility of a twisting movement being imparted to the progress of the clay column through the cutting operation.

To reduce the risk of distortion, a key 26 (Figure 1) is formed on the machine table which engages the keyway 14 of the column and effectively prevents any tendency for the column to "wander".

Tne completed arch formed by the blocks 2, 4 and 6 is shown in Figure 7 in section through the block 2. A cavity wall is formed ;i the bricks 24 and interior blocks 28 with a damp proof member 30 and insulation 32. A galvanised mild steel lintel 34 is inserted below the blocks, infilled and pointed in a conventional manner prior to plastering at 36.

Various mobications nay be made with the scope of the invention.

Claims

1. A feature arch comprising a plurality of blocks, of which a first block is of trapezium shape and is arranged between two groups of voussoirs to form an elongate series above a door or window aperture, a first of said groups of voussoirs comprising a row of second blocks identical to each other within the first group and having at least one exposed surface thereof in the form of a parallelogram other than a rectangle and a second of said groups of voussoirs comprising a row of third blocks, identical to each other within the second group, each block of said second group being a mirror-image of the corresponding block in said first group.

2. An arch as claimed in claim 1 wherein the two angles included in said parallelogram correspond to the angles included in the trapezium of said first block.

3. An arch as claimed in either one of claims 1 and 2 wherein the first block and the two groups of voussoir blocks are provided with bores forming a passage through each block connecting side surfaces thereof, all said bores communicating with each other to provide an elongate passageway adapted to receive reinforcing rods.

4. An arch as claimed in any one of the preceding claims wherein each block is provided with a transverse groove on a rear surface thereof, said groove connnecting side surfaces to the block.

5. A method of producing trapezium and voussoir blocks as for an arch as claimed in claim 1, including the step of extruding a column of brick clay and subjecting it to a cutting operation wherein cutting strips are arranged at an oblique angle with respect to a centre line of the column.

6. A method as claimed in claim 5, wherein the angle of operation of said cutting strips is adjustable between a first angle of the two angles of the parallelogram and its supplementary angle.

7. A method as claimed in either one of claims 5 and 6, wherein the cutting strips are in the form of cutting wires.

b. A method as claimed in any one of claims 5 to 7, wherein at least one bore is formed lengthwise within said column of brick clay.

9. A method as claimed in any one of claims 5 to 8, wherein a keyway is formed in an underside of the column of brick clay, said keyway being engaged by a key formed on a cutting surface against which said cutting strips operate.

10. A feature arch constructed and arranged substantially as hereinbefore described with reference to and as shown in the drawings.

11. A method of producing trapezium and voussoir blocks for an arch as claimed in claim 10, substantially as hereinbefore described with reference to the drawings.