GB2301135A - Plastics window frame joint connection - Google Patents

Abstract

The invention provides a joining piece for connecting hollow plastics window or door frame components and which can be used optionally to support a metal reinforcement member inside the component. The joining piece (4) has a body (8) with a cross-sectional shape which is intended to fit the internal hollow chamber of a plastics frame component. To the body (8) is attached a plug unit (6) which is shaped to fit within a channel region of a metal reinforcement member (3, 3a) and be fixed therein. A similar joining piece supports the opposite end of the member. The arrangement provides means for holding the reinforcement member rigidly and thus it gives greater stiffness to the assembled frame particularly when a steel reinforcement is used.

Description

PLASTICS WINDOW FRAME CONSTRUCTION This invention relates to a plastics window frame construction.

In the manufacture of replacement windows, the relevant frames are usually made of a thermoplastics composition with the corners of the frames being joined by a plastics welding process. The plastics composition is formed as an extruded profile which includes longitudinally-directed hollow chambers into which lengths of reinforcement material are inserted during a frame assembly operation. The physical strength of the plastics composition itself is therefore not a major factor in the finished frame since the strength and stiffness of the frame is determined largely by the characteristics of the reinforcement member.

For provision of the reinforcement member, it has been preferred to use aluminium in the form of an extruded section.

A particular advantage of aluminium is that the extrusion can be formed simultaneously with a longitudinally extended channel which can be used to secure a self-tapping screw to the end of the metal length. The need to firmly secure the end of the reinforcement member is particularly important in the formation of a tee-joint since a joint which relies solely on a weld of the plastics composition has only low strength.

An aluminium reinforcement member which carries an integral channel for a screw is thus a satisfactory constructional component and, of course, wherever the metal length is cut there will always be a channel end exposed which may be connected by a screw passing transversely through a straight length of a second reinforcement member to form a tee-joint.

The possibility of providing a channel for a screw has thus made aluminium a favoured material for the reinforcement member. There have been attempts to replace the metal of the member with steel instead of aluminium since steel is a much cheaper material. However, it is not possible to provide steel in the form of an extrusion having a screw channel and this has created difficulties in making a suitable fixing at the ends of a steel piece. Steel does give an increased strength and rigidity to the plastics frame construction but since the steel is formed by a rolling technique in a C-shape cross-section it is not possible to incorporate a screw channel in the cross-sectional shape.

There has been one attempt to provide a support for an end of a steel reinforcement member and this technique uses a tee-shaped metal joining piece which has one arm that is located in the reinforcement member and two arms lying in a straight line which can be secured to an inside wall of a window frame.

The presence of the two arms can thus cause an obstruction which leads to a difficulty in fitting the window glass properly and the arms make a very obvious change in the appearance of the window frame since they remain visible on the external plastics surface of the frame.

I have now discovered a construction of joining piece which is capable of being fitted to a frame without obstructing the internal opening of the frame.

According to the invention, there is provided a joining piece for connecting hollow structural components in making a tee-joint for a plastics window or door frame, the joining piece comprising a body arranged to fit closely within the hollow end of a first structural component, the body including a wall defining a longitudinally-directed screw hole for receiving and gripping a screw when required, the said screw being inserted transversely through a second structural component to enable the two components to be secured together in a tee-joint configuration.

Preferably, the joining piece comprises two or more screw holes for enabling the second component to be secured thereto.

The joining piece may support a plug unit which is capable of being secured to an internal metal reinforcement member for the structural component. The plug unit may be formed with a cross-sectional shape which will allow it to be inserted within a hollow channel of a metal reinforcement member. The plug unit may be joined to the body at a shoulder where there is a change in the cross-sectional shape of the joining piece.

The joining piece has a body which is arranged to fit the hollow end of a plastics frame. The reinforcement member is thus held within the hollow chamber of the plastics frame profile in a manner which will tend to prevent any possible twisting of one end of the plastics frame profile relative to the other end of the frame portion.

The invention further comprises a plastics frame profile including an internally-fitted reinforcement member with the joining pieces of the invention mounted at the ends thereof.

It further comprises a plastics frame profile fitted orthogonally to a second frame profile to form a tee-piece and which incorporates the joining pieces of the invention.

The invention additionally comprises a crucifix construction with a central limb of a plastics frame profile and two side arms of similar frame profiles extending therefrom on opposite sides.

The invention further comprises a plastics window or door construction embodying plastics frame profiles when including reinforcement members which are secured by means of the joining pieces of the invention.

By way of example, some particular embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a cross-sectional view of a plastics window frame profile with a steel reinforcement member located in a hollow chaber of the moulding, Figure 2 is a perspective view of a steel reinforcement member with the joining piece of the invention about to be inserted therein, Figure 3 is a side view of the joining piece of the invention, Figures 4 and 5 are end views taken respectively from the left and right hand ends of Figure 3, Figure 6 shows a window frame tee-piece construction, Figure 7 shows a crucifix construction, and, Figure 8 depicts a window frame including a crucifix frame construction.

As shown in Figure 1, a plastics window frame 1 in crosssectional view is seen to be formed by a technique which results in a number of longitudinally-directed hollow chambers being created in the moulding. One centrally positioned chamber 2 is intended to be occupied by a length of reinforcement material 3 which is inserted after the frame material has been cut to the required length for fabricating the window. In the present example, the reinforcement material 3 is a length of galvanised mild steel which has been formed by the manufacturer into a C-shape cross-section.

In order to provide a reliable fixing for the ends of the reinforcement material 3, the present invention provides a joining piece 4 (Figure 2) which at one end has a plug unit 6 suitably shaped so as to fit closely within the hollow interior of the reinforcement material 3. When the plug unit 6 has been pushed into the length of reinforcement material, the cut end of the material 3 is brought into contact with a shoulder 7 on the joining piece 4. At an end of the joining piece 4 remote from the plug unit 6, the joining piece is provided with a body 8 having a cross-sectional shape which corresponds to that of the chamber 2 in the plastics frame 1 profile.

This ensures that when the window frame is assembled, the reinforcement material 3 will be fully supported within the chamber 2 and any tendency for the plastics frame material to bend or for one end to be twisted with respect to the other end will be resisted by the presence of the firmly-supported reinforcement material 3.

In order to fix the joining piece 4 to the end of the reinforcement material 3, the worker doing the assembly operation is expected to drill a hole for a self-tapping screw at about the position of the line 5 in Figure 3. This hole (not shown) passes through the material 3 and enters the joining piece 4 so that the screw when fitted serves to permanently secure the two parts together.

The joining piece 4 is seen to be formed with two through holes 9 which are intended eventually to receive self-tapping screws and it is provided with ridged surfaces 11 which are arranged to be capable of being supported adjacent similar ridges on the internal surface of the chamber 2. This ensures that the joining piece 4 will be prevented from movement relative to the chamber 2 once the piece 4 has been inserted therein.

Figure 4 is an end view taken from the left hand side of the Figure 3 view. Figure 5 is a similar view taken from the opposite end, and in this view, the outline of the reinforcement material 3 has been included so it will be apparent that whilst the material 3 is not in close contact with the plastics walls along the full length-of the material 3, the joining piece 4 ensures that there is a close fit at the ends of the material 3.

Figure 6 shows a tee-piece construction, this is a type of joint which is frequently required in window frame fabrication. To construct this joint, the plastics material for the horizontal part of the frame 1A is cut to length and the end of the frame material is suitably shaped so it will make a good fit against the proposed vertical part of the frame. A length of reinforcement material 3A for the frame horizontal part is fitted at its end with a joining piece 4 and the joining piece and reinforcement material are secured together by a drilled hole and screw as already described.

The frame horizontal part 1A may then be brought into contact with the frame vertical part, the vertical part 1B being already provided with its own internal reinforcement member 3B. The assembly worker will then drill a hole in the vertical part 1B opposite the place where the horizontal part is to be fixed and the drilling will be arranged to pass through the plastics wall and through the reinforcement material 3B of the vertical part. The assembly worker will then be able to insert a screw 12 through this hole so it will become secured in the screw hole 9 of the joining piece 4. A second screw is secured in the piece 4 in a similar way. By tightening these screws, it is possible to pull the reinforcement material 3A length up tightly within the plastics frame part and a limited amount of adjustment may be made if this should be necessary.

Figure 7 shows the construction of a crucifix shape where a vertical frame part 1B is provided with two horizontal frame parts 1C and 1D located on opposite sides of the vertical part. To fabricate this joint, the vertical frame part 1B provided with its reinforcement member 3B is initially fitted with two joining pieces 4 by using two long screws. One of these screws 12 is passed through one joining piece, then through the plastics and reinforcement material 3B of the vertical frame part 1B and the screw is then secured in the second joining piece 4. A second long screw 12 is then passed in the opposite direction, through a joining piece, through the reinforcement material 3B of the vertical frame part then is secured in the opposite joining piece.With the two joining pieces now fixed on the vertical frame part 1B, the correct lengths of reinforcement material may be pushed into the plug units and be secured thereto by self-tapping screws. The plastics frame material for the side arms may then be slid over the lengths of reinforcement material to enable the construction of the frame crucifix to be completed.

Figure 8 shows a completed window frame including the crucifix construction as well as four tee-piece joints.

For the sake of clarity in the drawing, the positions of only four joining pieces have been shown. The joining pieces of course are located internally and they would not be visible from the outside of the plastics frame.

It will be clear that whilst the foregoing description relates mainly to the construction of a window, the possibility of using the joining piece for tee-pieces and crucifixes may also be applied to a door. This door could be fully or partially glazed or it could just be a panelled door with the tee-piece and crucifix construction used for adding decoration or strength.

It is not essential that the joining piece or two joining pieces should always be used with a length of reinforcement member. In the construction of a door which has a horizontal transom provided in the middle region of the door, the joining pieces may be used to support the transom relative to the left and right hand sides of the door. Since the joining pieces have a profile which exactly fits the hollow chamber of the plastics transom, the joining pieces even when they are not connected by a reinforcement member can still provide a secure support for the transom.The worker assembling the door has the options of fitting (1) a full length steel reinforcement within the plastics transom, (2) a short length of steel reinforcement at each end of the transom with a central gap which will allow a letter box opening to be provided in the middle of the transom and (3) no steel reinforcement which will still give a strong fixing of the transom to the vertical sides of the door and allow a letter box opening to be made at any position along the transom. These options allow doors of different appearance and internal strength to be provided by use of the joining piece of the invention.

The preferred material for producing the joining piece of the invention is a hard plastics material such as a polyvinyl chloride (PVC) composition. This material is to be favoured over an electrically conductive material like aluminium since that could be subject to electrolytic corrosion over an extended period of time when in contact with steel.

Use of the joining piece of the invention for enabling a steel reinforcement to be incorporated in a plastics frame section has been found to increase the stiffness and strength of that section as compared to an aluminium reinforcement.

With aluminium, the stiffness available does lead to some constructional difficulty when the side length of a window frame exceeds 1200 millimetres. This limitation does not occur when a steel reinforcement is used and consequently with steel and the present joining piece a considerably larger frame size can be made, if this is required.

One of the advantages of adding increased stiffness to a window frame is that the frame becomes less susceptible to movement due to wind pressure on the areas of glass.

Consequently, there is a reduced movement of the frame material which supports the glass and therefore less movement of the sealing mastic which prevents air and moisture leaking between the frame and the surrounding brickwork forming the window opening. The sealing mastic therefore becomes less stressed and it will be likely to remain an effective sealant for a longer time. An increased stiffness of the frame material thus helps to prolong the life of the sealant round the window edges.

The joining piece is capable of being made at a low cost and when used with the steel reinforcement it can show a saving in the total window manufacturing cost as compared with the conventional aluminium reinforcement construction.

The joining piece provides an adjustment means which aids pulling-in of the joint components and this can lead to greater accuracy in producing a window to fit a predetermined size of opening. Use of the joining piece does not make any outward change in the external appearance of the window and, if a short-bolt lock is required, there is no obstruction to the internal wall of the window frame which would be likely to create a difficulty in the fitting operation.

The foregoing description of embodiments of the invention has been given by way of example only and a number of modifications may be made without departing from the scope of the invention as defined in the appended claims. For example, in the joining piece 4 the end surface 10 (Figure 3) at the outer end of the piece does not have to be shaped as a plane surface. Since it is intended to be supported against a side-wall of a plastics frame, the surface 10 may be shaped perhaps with angled surfaces and planes at different levels so that it will make a satisfactory butt joint against the side wall.

Claims (11)

1 A joining piece for connecting hollow structural components in making a tee-joint for a plastics window or door frame, the joining piece comprising a body arranged to fit closely within the hollow end of a first structural component, the body including a wall defining a longitudinallydirected screw hole for receiving and gripping a screw when required, the said screw being inserted transversely through a second structural component to enable the two components to be secured together in a tee-joint configuration.

2 A joining piece as claimed in Claim 1, in which the body comprises two or more screw holes for enabling the second component to be secured thereto.

3 A joining piece as claimed in Claim 1 or 2, in which the body supports a plug unit which is capable of being secured to an internal metal reinforcement member for the structural component.

4 A joining piece as claimed in Claim 3, in which the said plug unit is formed with a cross-sectional shape which allows it to be inserted within a hollow channel of a metal reinforcement member.

5 A joining piece as claimed in Claim 3 or 4, in which the said plug unit is joined to the body at a shoulder where there is a change in the cross-sectional shape of the joining piece.

6 A joining piece as claimed in any one of Claims 3 to 5, in which the said plug unit includes means for enabling the reinforcement member to be attached thereto by a screw fastener.

7 A plastics frame assembly in the shape of a tee-piece, when including a joining piece as claimed in any one of Claims 1 to 6.

8 A plastics frame assembly in the shape of a crucifix, when including a joining piece as claimed in any one of Claims 1 to 6.

9 A plastics window or door frame, when including a joining piece as claimed in any one of Claims 1 to 6.

10 A joining piece for connecting hollow structural components, substantially as hereinbefore described with reference to any one of the accompanying drawings.

11 A method of constructing a plastics frame assembly, substantially as hereinbefore described.