GB2363808A - Dowel for joining blocks - Google Patents

Abstract

A dowel 2a having a first plug 3 at one end and a second plug 4 at the other end, and a middle portion 6 between the plugs, each plug having external retaining features arranged to resist its movement in a direction from the respective plug towards the middle portion, the second plug being expandable to cause its retaining features to move radially outwards by means of a force applied to the second plug, the middle portion being configured so as to limit insertion of the first plug into a hole 212 in which the first plug is capable of being snugly received. Wedge 27 and 28, provides expanding force on said second plug when driven into hole 16, this can be achieved with the use of another dowel 2b and protective sleeve 42. Blocks 1a and 1b are joined either permanently or temporarily by including the wedge or not including the wedge respectively.

Description

2363808 DOWEL

Description

The present invention relates to a dowel, for example a dowel for a construction kit suitable for constructing a structure such as a wall.

It is known to construct a solid wall using bricks and mortar The bricks are typically substantially cuboid in shape, with a prism-shaped recess in the two largest faces, which lie opposite one another and which are also the top and bottom faces, for receiving mortar The bricks can be considered also to have front and rear faces which form the main external surfaces of the wall, and two side faces, which are the smallest faces Such a wall is constructed in a layered manner, the first layer being created by connecting bricks at their side faces with a layer of mortar The second layer is added by spreading mortar on the top faces of the first layer and the bottom faces of the bricks to be used for forming the second layer, and, typically, placing the second layer bricks on the top surface of the first layer bricks such that their side faces align with the vertical centrelines of the front and rear faces of the first layer bricks The third layer can be added in a similar manner, such that the third layer bricks are in alignment with the first layer bricks The fourth layer is added in a similar manner, such that the fourth layer bricks are in alignment with the second layer bricks Subsequent layers can be added so as to continue this alignment pattern Variations on this alignment pattern may be used.

This type of wall is most suitable for permanent buildings, such as houses and offices, or other places where a very strong and permanent wall is required One reason for this is that it is relatively time-consuming and expensive to construct such a wall This is firstly because the bricks must be manufactured from clay by a process which includes baking It is of course possible to buy them ready-made but the cost is dictated by the manufacturing process Secondly, mortar must be mixed This mixture rapidly deteriorates in air, therefore it must either be used quickly or kept in motion, by, for example, a cement mixer This requirement, together with the difficulty of accurately aligning the bricks, makes it awkward for unskilled people to construct a wall themselves.

Another reason for using a brick and mortar wall as a permanent structure is that once the mortar has set it is very difficult to de-construct the wall, especially if the bricks are to be kept intact for re-use A further reason is that a brick wall is fairly heavy and therefore requires foundations in order to be safely stable.

If a less permanent structure is required, or a permanent structure is to be constructed in a situation where it would be difficult to provide foundations, one known solution is to use a wooden fence Wooden fences can be constructed in a variety of styles, but in general they are constructed from long, thin sections of wood which are held together by nails or the like This tends to make them cheaper than brick walls, and therefore suitable for applications such as garden sheds or fencing between gardens However, they are much less sturdy than brick walls Secondly, they are not easy to construct, since the sections of wood must be correctly aligned and the nails or other fixings applied whilst retaining the correct alignment Thirdly, de-construction is not particularly easy, since it would involve removal of the nails or other fixings, which may well have begun to rust by that time.

There is therefore a need for a wall which can be easily and cheaply constructed in a variety of locations Ideally such a wall would be stronger than a wooden fence, and capable of being de-constructed if required This would be useful for non-professional builders who wish to construct walls, or structures comprising walls, themselves, for example in their gardens Preferably, it would be possible to buy ready-made components for constructing such a wall.

It has been proposed to use a wooden dowel system to fix together wooden blocks Known systems use simple cylindrical dowels and many gadgets exist in the marketplace for positioning and determining the depth of holes to receive the dowels Joints created by using such wooden dowels have to be clamped and glued to form a permanent joint It would therefore be desirable to provide a hidden dowelling system that does not need other types of fixing such as glue.

Ideally, such a system would be capable of being manufactured in volume at a reasonable price It should also be capable of being constructed using few tools and not require professional skill to construct There is also a need for a system to allow both temporary i e capable of being dismantled, and permanent construction without the use of glue or clamps or other such awkward and messy fittings Furthermore, it should not require a complicated system to determine the depth of the receiving holes and correctly align the dowels.

According the present invention, there is provided a dowel having a first plug at one end and a second plug at the other end, and a middle portion between the plugs, each plug having external retaining features arranged to resist its movement in a direction from the respective plug towards the middle portion, the second plug being expandable to cause its retaining features to move radially outwards by means of force applied to the second plug, the middle portion being configured so as to limit insertion of the first plug into a hole in which the first plug is capable of being snugly received.

The invention will now be described by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a third angle projection of a block used in construction of a wall according to the invention.

Figures 2 a-d show a dowel suitable for use in constructing a wall according to the invention.

Figure 3 shows a wedge for use with the dowel of figure 2.

Figures 4 a-d show a dowel being used to join two blocks together.

In the figures, like reference numerals indicate like parts and lowercase letters are used to distinguish between several like parts.

The description below relates specifically to the joining of wooden blocks to build a wall or similar structure but it will be seen that the technique and parts could be used for other constructions and for joining objects of other materials.

Figure 1 shows three views of a standard block, indicated generally by reference numeral 1 Figure 1 a is a front view, figure 1 b is a top view and figure 1 c is a side view of the block The block's length could conveniently be, for example, 6, 8 or times its width W This block is suitable for use with the dowel of the present embodiment of the present invention but differently-designed blocks could also be used.

The block 1 is made of wood A number of different types of wood would be suitable for making the block; the appropriate one would be chosen for the intended application of the wall to be constructed The wood of the blocks could be treated to improve its durability or to have a decorative finish It would of course be possible to use different materials, but wood is probably the most convenient for many applications.

Block 1 is substantially cuboid in shape It has a width W, a vertical depth D and a length L The dimensions may vary but in this embodiment the length L is selected to be 8 x W It has a top face 114, a front face 116, a right hand side face 118, a left hand side face 1 1 0,and a bottom face 112 It will be appreciated that the block has respective equivalent rear and opposite side faces.

Perpendicular to the top face 114 and centred across the width of the block are drilled four holes, through the entire depth of the block 1 Each hole has a straight-sided through-bore that passes through the block, and a wider section where it meets the upper surface of the block, which defines seat 120 as a cut-out at the upper surface of the block 1, suitable for accepting and restraining the collar of a dowel, as will be described below Referring specifically to block 1, the first hole 212 is centred '/2 W from the left hand side face 110 The second hole 214 is centred Y W from the right hand side face 118 The third hole 216 is centred Y/2 W to the left of the centreline C/L of the block as measured along the length L, and the fourth hole 218 is centred Y/2 W to the right of the centreline C/L.

The distance between the centres of holes 216 and 218 is therefore 1 W The holes all lie on the longitudinal centre line of the top face 114, with their centres therefore 1/2 W from front face 116.

Thus it can be appreciated that (ignoring the seats 120) the block is symmetrical about all of its three central axes.

Construction of a wall by the use of dowels in blocks such as those of figure 1 is described in the applicant's co-pending UK Patent Application No 0018118 0, the contents of which are herein incorporated by reference This application describes the use of blocks of different lengths, corner blocks, capping layer blocks and ground blocks suitable for constructing a convenient wall structure.

Some types of dowel are described in that application The following description will discuss a different dowel which has now been developed.

Fig 2 a shows a side elevation and figure 2 b shows a top elevation of a dowel, labelled generally with reference numeral 2 Figure 2 c shows a cross section through the dowel 2 at line X-X' of figure 2 b and figure 2 d shows a cross section of the dowel 2 at line Y-Y' of figure 2 a.

Dowel 2 is made from plastics material such as Nylon or polyethylene and has a total length which is less than the depth of the block 1 It is very generally cylindrical in cross section and has a bottom portion 3 and a top portion 4, which are rotationally fast with respect to one another It would be possible to use other materials such as wood to make such a dowel, but plastics materials have the advantage that they can conveniently be moulded to shape.

The bottom portion 3 has a collar 6 around its top circumference where it meets top portion 4 The collar projects radially from the bottom portion 3 The collar is of a size that fits neatly into the seat 120 recessed into the holes 212, 214, 216, 218 in the block 1, but will not pass through the through-bore sections of the holes Around most of the remainder of the circumference of the bottom portion 3 run spaced-apart circumferential grooves 81 of triangular cross-section, which define corresponding spaced-apart circumferential teeth 82 around the bottom portion 3 The maximum diameter of the bottom portion at the tips of the teeth is slightly larger than the diameter of the through-bore sections of the holes in the block 1 This means that a certain amount of force is required to insert bottom portion 3 in a block 1 and a tight fit will be achieved By virtue of the teeth being oriented in an upwards configuration, they allow the dowel 2 to be relatively easily driven into the holes of block 1 but make it difficult to remove accidentally The arrow-shaped groove 11 shown in figure 2, which intersects the teeth, is a decorative feature on which can be engraved writing or a trademark or symbol etc It also indicates to a user that the bottom portion of the dowel, on which it is formed, should be inserted into a block before the upper portion, and in the direction shown by the arrow.

The top portion 4 has a maximum diameter that is slightly less than that of the holes 211, 214, 216, 218 in the block 1 Around its circumference run recessed grooves 9 defining between themselves several horizontal ribs 10 for resisting removal of the dowel once locked in a hole It should be noted that the peripheral surfaces of these ribs 10 are set at an angle greater than vertical as measured outwards from the centre of the dowel 2 so that they effectively point outwards and downwards Thus, when the top portion is inserted into the hole in the bottom of a block and its diameter expanded as will be explained below, the ribs 10 can act to restrict relative movement to remove a block upwards from the dowel 2 in an analogous way to the teeth 82 but in the opposite direction More or less ribs 10 than are shown in figure 2 could be provided.

Running vertically from the top 18 of dowel 2 almost the full length of the top portion 4 and cutting through the ribs 10 are two grooves 12 positioned opposite one another around the circumference of the top portion 4 of the dowel 2 The dashed lines in figure 2 c show that the thickness of the material at these two grooves is very small in comparison to the general material thickness elsewhere on the dowel, so that only a thin layer of material 14 separates the base of the grooves 12 from the sidewall of a central hole 16 of dowel 2 The reason for this will be explained below when use of the dowel 2 is discussed.

It would be possible to use grooves, teeth and ribs of different shapes from those shown in figure 2.

Centrally positioned and running the full length of the dowel 2 is central hole 16, which has a circular cross-section This hole is widest at the top 18 of the dowel 2 and evenly tapers down to a smaller diameter at the base 20 of the dowel.

Hole 16 is sized so that in the region of base 20 it fits snugly over the top of a wedge (to be described with reference to figure 3) and in the region of top 18 it can comfortably receive the tip of the wedge As a consequence of this taper the walls 22 of the upper portion 4 of dowel 22 are thinner than the walls 24 of the lower portion 3 The outer base 26 of the dowel 2 where the side walls are thickest is finished square.

In general terms, the dowel 2 is designed so that when the bottom portion 4 is driven into holes 212, 214, 216, and 218 of a first lower block 1 a, it becomes fixed such that the collar 6 sits in seat 120 and the top of the collar 6 is flush with the upper surface 114 of the block Ia Thus the top portion 4 of the dowel 2 is in a position to receive holes 212, 214, 216, and 218 of a second, identical upper block 1 b to be placed on top of the first block 1 a At that point, the teeth 82 hold the dowel fast in the holes of the lower block However, since the diameter of the top portion of the dowels is less than that of the holes in the upper block, the upper block can be slid easily down to envelop the projecting upper portions of the dowels.

Fig 3 a shows a side view and figure 3 b shows a top view of a generally conical wedge, indicated generally with reference numeral 27 Figure 3 c is a cross- sectional view taken along the line A A' through conical wedge 27 It is conveniently made from the same or a slightly harder material than the dowel It is generally circular in cross section and its total length is about half the total length of the dowel 2 shown in Fig 2.

The upper portion 28 of conical wedge 27 is a peg with a rounded top 30 It is generally cylindrical with four sections 29 removed leaving a section in the form of a right-angled cross which extends down the length of the upper portion 28 in the form of ribs 31 The diameter of this upper portion 28 is slightly larger than the diameter of the hole 16 of the dowel 2 at its bottom face 20, so that when the upper portion 28 is pushed by hand from the bottom of the dowel into the hole 16 of the dowel 2 it is held in position in a snug fit, as mentioned previously.

The lower portion 32 of conical wedge 27 has a length that is less than the upper portion 4 of the dowel 2 It is generally shaped as a truncated cone with a rounded end 34 The widest part 36 of the cone, adjacent to upper portion 28, has a diameter that is at least 20 % larger than hole 16 at the top 18 of the dowel 2 The wedge 27 has no grooves at this point, thus material extends around its whole circumference so it is cylindrical here As its diameter is greater than the adjacent upper portion 28, it forms a square shoulder 38 Consequently, when the upper portion 28 of the wedge 27 is pushed into dowel 2, as will be explained below, the shoulder 38 sits on the square cut base 26 of the dowel around its whole circumference.

The rounded end 34 of the wedge 27 has a diameter which is slightly less than hole 16 at the top 18 of the dowel 2 so that when the wedge 27 is pushed by hand into the top of the dowel 2 it can be held in position.

From the shoulder 38 to the rounded end 34 of the wedge 27 four hollows 39 are removed leaving four prominent ridges 40 arranged in cross-section as a right angled cross which extends up the wedge 27 to shoulder 38, apart from in the close vicinity of shoulder 38, at which point the wedge 27 is cylindrical, as mentioned previously.

The dowel 2 is designed so that it may be used for temporary constructions, which can be levered apart, or when used in conjunction with the wedge 27, for a more permanent wall structure that would be more rigidly fixed together and more difficult to dismantle In both cases the bottom portion 3 of the dowel 2 is driven into pre-drilled holes 212, 214, 216, 218 of a first, lower block 1 a, until the collar 6 sits in recess 120 (Fig 4 A) The teeth 82 facilitate this and prevent the easy removal of the dowel 2 by virtue of their upwards configuration The upper part 4 of the dowel 2 protrudes from the top face 114 of the first, lower block 1 a and the pre-drilled holes of a second, upper block 1 b are placed over these and pushed firmly into position (Fig 4 B).

If the wall construction is to be temporary, the wedge 27 is not used but dowels 2 are simply inserted into the pre-drilled holes of the next and subsequent layers of blocks Since the collar 6 of dowel 2 is designed to sit in seat 120, when a dowel 2 is placed in a lower block 1 a, its movement will stop when the collar is seated in seat 120, so that the blocks la, 1 b will sit flush together Furthermore, since the blocks are merely butted together and the dowels 2 are suitably sized, whilst the wall is secure for as long as it is needed, it is possible to deconstruct it easily, by simply levering the blocks apart There are no bonding agents such as glue or cement involved, and no metal fixtures such as nails to go rusty.

However, if a more permanent structure is required use is made of conical wedges 27 The construction process will now be described in more detail with reference to figures 4 a to 4 d.

Figure 4 a shows the first stage of joining together a first, lower block 1 a and a second, upper block I b The bottom portion 3 of a first dowel 2 a is hammered into a hole 212 in block la The dowel 2 a is stopped in the correct vertical position by virtue of collar 6 fitting into seat 120 of block 1 a The upper portion 4 of dowel 2 a rests above the top face 114 of block 1 a.

Next, upper portion 28 of a conical wedge 27 is pushed into hole 16 from the base 20 of a second dowel 2 b.

Referring now to figure 4 b, a second block l b is placed on top of first block 1 a so that drilled receiving hole 218 of block 1 b fits over upper portion 4 of first dowel 2 a and blocks 1 a, lb are held flush together The reason that it is hole 218 of block l b rather than hole 212 is because of the preference for constructing a wall with alternate layers of bricks being in a staggered arrangement, as is known in the art and described in the applicant's co-pending UK patent application no 0018118 0.

Then, the dowel 2 b, complete with wedge 27, is hammered vertically downwards into hole 218 of second, upper block 1 b, so that the rounded end 34 of the wedge 27 centres over hole 16 of dowel 2 a and has moved some way into it.

Having reached this stage, some force is required to drive wedge 27 further into hole 16 of dowel 2 a in order to make the construction permanent in nature and to allow the lower portion 3 of dowel 2 b to be pushed into block 1 b until collar 6 sits flush in recess 120 This stage is shown in figure 4 c.

In order to drive the dowel 2 b further into hole 16 of block 1 b, use is made of the fact that the square base 26 of the walls 24 of dowel 2 b acts on the shoulder 38 of the wedge 27 and as the lower part of the dowel 2 is hammered into hole 218 the wedge 27 is forced into hole 16 of the first dowel 2 a, the collar 6 preventing the lower dowel 2 a from being forced downwards As the wedge 27 is forced into hole 16 the four ridges 40 of the wedge 27 stretch the thin material 14 at the base of the grooves 12 in the upper portion 4 of the dowel 2 a, forcing the ribs 10 against the wall of hole 218 of block 1 b and locking the dowel 2 firmly in position.

The final position is shown in figure 4 d, in which seats 6 of blocks 1 a, 1 b are both flush with the top faces 114 of their respective blocks It is convenient for thin material 14 to be frangible so that one or both of grooves 12 splits, thus separating upper portion 4 of dowel 2 a vertically, which allows it to be forced against the walls of hole 218.

To protect the dowel 2 b from damage whilst being hammered into position, a steel sleeve 42, whose length is slightly longer than the upper portion 4 of the dowel 2 b is fitted over the top portion 4 of the dowel 2 b so that its bottom edge rests on the upper surface of the shoulder 6 The steel sleeve 42 is generally cylindrical in shape and is open at its bottom end so that it can be fitted over the dowel 2 b Its top end is a suitable shape to minimise deformation during repeated hammering and to efficiently transfer the impact force to the dowel 2.

Thus the force of hammering is transferred directly and evenly onto the stronger lower portion 3 of the dowel 2 A suitably tough material other than steel could be used.

It can be understood from figure 4 d and the description above that the lengths of the two portions 3, 4 of dowel 2 are sized at slightly less than 1/2 D so that when in position fixing two blocks 1 a, 1 b, the two dowels 2 a, 2 b do not touch Instead they are separated by roughly the depth of cylindrical portion 36 of wedge 27.

As is understood from figure 1, in order to connect any given two blocks, there will be more than one dowel connection required Thus in practice, the above- described process would be the same for the equivalent holes in blocks I a and 1 b and the process could furthermore be used to construct a wall as described in the applicant's co-pending UK patent application number 0018118 0 One advantage that this process brings is that there is no need to hammer the blocks themselves, but rather it is always the dowels 2 via sleeve 42 which are hammered This is useful if it is undesirable to hammer the blocks directly, for example if they are pre-painted and damage to the paint needs to be avoided.

If it is required to make a temporary construction more permanent, the blocks can be levered apart since the upper part of dowel 4 is slightly smaller than the pre drilled holes The lower portion of the dowels 2 will however remain fixed in their holes It would be possible to completely remove the dowels 2 should this be necessary, but some force would be required to act against triangular teeth 82.

Otherwise, to re-erect the structure or reuse the blocks 1 in a more permanent manner the bottom of the wedge 34 is pushed into hole 16 of the protruding half 4 of a dowel which remains fixed in a hole 212, 214, 216, 218 As the upper block, complete with its dowels, is placed in position, the rounded ends 30 of wedges 27 centre on holes 16 of dowels 2 contained in the upper blocks As the block is hammered into position the wedge is driven in and the two blocks are permanently fixed.

Any structure constructed as described above can be fitted to the ground using ground plates and can be finished off using capping sections as described in UK Patent Application No 0018118 0.

It will be appreciated that other sizes of blocks can be used, with different arrangements of holes It would also be possible to use holes and dowels of a different shape, for example square Furthermore, if desired, the blocks could be constructed with dowels incorporated, for example, just in the upper faces, although this would be likely to make a kit more expensive The holes could of course be formed by a method other than drilling In certain forms, the construction kit would be suitable for use as a toy.

It would also be possible to provide the dowels with a built-in wedge attached to the bottom, so that the whole would then be inserted into a hole in a block as per figure 4 c Such a wedge could optionally be formed so as to be easily detached from the dowels as desired.

The actual dimensions of the blocks, dowels and wedges could be widely varied, depending on the intended application Furthermore, it is not necessary for all the holes in a particular block to be the same size, although since suitably sized dowels are needed for proper construction of a wall, economy of manufacture and packing is maximised by using identically sized holes Although wood is the most suitable material for the blocks, other materials such as plastics or metals could be used The blocks and dowels could be sold as a kit for building a particular- sized wall, or could be sold loose, so that customers could buy exactly the number required and could vary the dimensions of the wall and the choice of capping section The shape of the dowels and wedges could be varied within the scope of the invention.

It would also be possible to use a wall constructed in this way for many other applications In particular, such a wall could be used horizontally for decking and tabletops It could also be used (in various sizes and dimensions) for fixing panels, block paving, finials, timber edging etc It would also be useful for holding awkward shaped pieces of wood together whilst gluing two surfaces together.

Claims (1)

1 A dowel having a first plug at one end and a second plug at the other end, and a middle portion between the plugs, each plug having external retaining features arranged to resist its movement in a direction from the respective plug towards the middle portion, the second plug being expandable to cause its retaining features to move radially outwards by means of force applied to the second plug, the middle portion being configured so as to limit insertion of the first plug into a hole in which the first plug is capable of being snugly received.

2 A dowel according to claim 1, wherein the second plug has an external wall defining a hollow interior whereby the external wall may be subjected to a radially outward force upon insertion of a wedge into the interior.

3 A dowel according to claim 1 or claim 2, wherein the first plug, the second plug and the middle portion are integral with each other.

4 A dowel according to claim 3, wherein the dowel has a central hole extending through the first plug, the second plug and the middle portion and which hole tapers from the first plug to the second plug.

A dowel according to any preceding claim, wherein the second plug comprises one or more mutually radially outwardly movable segments.

6 A dowel according to claim 5, wherein the external retaining features of the second plug are on the external surfaces of the one or more segments.

7 A dowel according to claim 5 or claim 6, wherein the one or more segments are joined by one or more zones of weakness for allowing expansion.

8 A dowel according to claim 7, wherein the zones of weakness are formed of a frangible material.

9 A dowel according to any preceding claim, wherein the middle portion is a radial projection.

A dowel according to any preceding claim, wherein the external retaining features of the first plug are triangular in cross-section, thus forming teeth for resisting movement of the dowel.

11 A dowel according to any preceding claim, wherein the external retaining features of the second plug are recessed grooves defining between themselves a plurality of horizontal ribs whose peripheral surfaces have an external angle for resisting movement.

12 A dowel according to any preceding claim which is made of plastics material.

13 A wedge for use with the dowel of any of claims 2 to 12.

14 In combination, a dowel according to any of claims 1 to 12 and a wedge for subjecting the second plug to the force.

A combination as claimed in claim 14 as dependent on any of claims 4 to 12, wherein the wedge comprises:

a first portion sized for snug reception in the hole within the first plug of the dowel; and a second portion having an increasing diameter along its length towards the first portion, sized in the region of its length distal from the first portion for loose reception in the hole in the second plug of the dowel and sized in the region of its length proximate to the second portion for expanding the second plug of the dowel.

16 A combination as claimed in claim 15, wherein the second portion of the wedge has ridges running along its length which are configured to bear on the hole within the second plug of the dowel for causing the expansion.

17 A combination as claimed in claim 15 or claim 16, wherein the second portion of the wedge is able to be acted on to expand the second plug of the dowel when its first portion is inserted into the first plug of a second similar dowel and the second dowel is subjected to a force on its middle portion.

18 A combination according to claim 17, wherein the second dowel is configured to be subjectable to a force by transmission of a force from impact on a sleeve contacting the middle portion of the second dowel.

19 A combination according to any of claims 14 to 18, wherein the wedge is made of the same or a harder material than the dowel.

A dowel substantially as herein described with reference to the accompanying drawings.

21 A combination of a dowel and a wedge substantially as herein described with reference to the accompanying drawings.