GB2093144A

GB2093144A - Improvements in greenhouse frames

Info

Publication number: GB2093144A
Application number: GB8107642A
Authority: GB
Original assignee: MARLEY TRIDENT Ltd
Current assignee: MARLEY TRIDENT Ltd
Priority date: 1981-02-09
Filing date: 1981-03-11
Publication date: 1982-08-25
Also published as: GB2093144B

Abstract

In a framework built up from frame members extruded from aluminium alloy, the structurally important joints A, B, C are made up by bolting the meeting frame members e.g. 1, 2 to jointing brackets e.g. 10 rather than to each other. The brackets incorporate structural features which stiffen the joints and inhibit pivoting of the frame members about the joints. <IMAGE>

Description

SPECIFICATION Improvements in greenhouse frames This specification is concerned with improvements in the frame structure of greenhouses, in particular greenhouses having a frame made up from extruded metal glazing bars.

A typical current greenhouse frame structure is described in patent specification no. 1 025751. At the corners formed by the junction of various frame members e.g. at the ends of the ridge member or the corners of the eaves, the meeting glazing bars or frame members are bolted to each other and the joint is stiffened by attaching a gusset plate. A similar connection is used at the junction of door frame members with sloping roof members or rafters.

Despite the use of the gusset plates, the joints made in this way tend to be insufficiently rigid, and the provision of cross struts to support the main structural members is necessary.

The following description indicates how this problem can be alleviated by using a jointing bracket at each junction and bolting the frame members to the bracket rather than to each other.

Three frame joints are described each using different forms of jointing brackets. The inventive concepts underlying these brackets are defined in the appended claims.

In the accompanying drawings: Fig. 1 shows an end view of an assembled greenhouse frame indicating the 3 joints at A, B, and C, Figs. 2a and 2b show in detail the joint A, Figs. 3a and 3b show in detail the joint B, and Fig. 4 shows in detail the joint C, with Figs. 4a, 4b and 4c being section on lines a-a, b-b, c-c respectively of Fig. 4.

Referring to the drawings, Fig. 1 shows the general configuration of a greenhouse framework incorporating 3 new forms of jointing brackets.

The greenhouse is assembled from glazing bars which are metal e.g. aluminium or aluminium alloy, extrusions. The two joints A are each formed between one end of a ridge member 1 and the adjacent endmost sloping glazing bars or rafters 2.

The joints B (one not shown) are formed between the lower end of the rafter 2, the upper end of a corner post 3, and one end of an eaves glazing bar 4, which is usually shaped to include an integrally formed gutter. The joints C (two at the opposite end not shown) connect a wall post 5 and horizontal tie bar 6 to an intermediate point on the rafter 2. At one end of the greenhouse the members 5, 6 can be used as the basis of a door frame. The frame structure is reinforced generally by oblique struts 7 connected between the wall posts or the joints B and sill members 8, to which the lower ends of the wall posts are also connected.

Figs. 2a and b show the construction of the joint A between the ridge member 1 and end rafters 2 (only one rafter shown). The jointing bracket 10 used for this joint has two arms 11 which are set at the angle which will be formed by the greenhouse roof.

The ridge member 1 has on each side outspread flanges 12, also set at the roof angle, which sit on the bracket 10 against the arms 11 and are bolted to the bracket. The upper ends of respective rafters 2 are then also bolted to the arms 11. The ridge member 1 shown in Fig. 2a is of inverted U-shaped cross section, but other shaped ridge members with similar outspread flanges could be used, for example that shown in Fig. 5 of the above mentioned specification no.

1025751. The other flanges on the ridge member are used conventionally for engagement with glazing clips etc.

The bracket 10 preferably incorporates an abutment portion 1 3 placed at the junction of the arms 11 and protruding beyond the arms. The abutment portion 13 acts as a stop against which in particular the ridge member 1, and also the rafters 2, may be located. The joint may be stiffened, and the location of the bracket against the ridge member rendered more positive, by inserting a self-tapping screw 14 through a bore 22 in the abutment portion 13 to engage a screw groove 1 5 formed integrally with the ridge member 1 during extrusion. The screw engagement is shown as taking place at the apex of the ridge member and abutment portion, but this position is not critical and could be varied for different shaped ridge members, for example a hollow or U-shaped cross-section ridge member.

The latter need not necessarily be bolted to the bracket 10 through flanges similar to flanges 12 but could be bolted at the base of the hollow or U-shaped cross-section.

In the preferred form of the jointing bracket 10 as shown in Fig. 2a, the abutment portion 13 is shaped so as to close off the end of the ridge member 1. The screw connection between the abutment portion and the ridge member ensures a good seal against rain water. The portion 1 6 of the arms 11 on which the flanges 12 sit is preferably extended into the ridge member so that the bolt hole 17 through which the flange is attached is in a different vertical plane from the bolt hole 1 8 to which the rafter is attached. This again helps towards the rigidity of the joint. The arms 11 are preferably formed as angle bars so that the rafter can be attached through two bolts at right angles to each other (see Fig. 2b).Square headed holts are used so that the rafter 2 can be pushed on to the arms 11 of the bracket with the square heads engaging in T-slots 19 formed in the rafter during extrusion. By this means the need to drill holes in the rafter is avoided and the bolt heads are prevented from turning during tightening. The portions 1 6 of the arms 11 which receive the flanges 12 are slightly recessed. This provides a lip 20 which is engaged by the edge of the flange and thus resists spreading of the ridge member when a load i.e. the weight of the glass panes is applied to it.This recess also means that the flange 1 2 when bolted to the bracket has its outer surface flush with the outer surface of the arm 11 (see Fig. 2b) so that the rafter 12 may be slid onto the arm 11 with its T-slots in engagement with the square headed bolts and slid right over the flange 12 to locate against the abutment portion, again contributing to the rigidity of the joint by resisting any tendency for the flanges 12 to spread outwards when a load is applied to the ridge member.

Figs. 3a and b show a jointing bracket 30 which is formed in accordance with the same concepts as the bracket 10 but has a different configuration to suit the joint formed at the junction of a corner wall post, a rafter and an eaves gutter member. As with the joint at the end of the ridge member, the bracket is used to connect two members (rafter 2 and wall post 3) lying in the same plane at an angle to each other and a third member (eaves/gutter member 4) lying in a plane at right angles to the first plane. As with the bracket 10 and ridge member 1, the bracket has two arms 31 set at the angle of the eaves and these are engaged with outspread flanges 32 on the gutter member 4, the flanges 32 being also set at the eaves angle. As before these flanges locate in a recess on the arms 31 and are bolted to the arms on an extended portion 33 of the arms.The end of the gutter member is located against an abutment portion 34 on the bracket and is secured against it by a self-tapping screw 35 which passes through the abutment portion and engages a screw groove 36 formed in the gutter member extrusion. Again the arms 31 are of angle bar section so that they may be connected to the angle bar rafters 2 and corner posts 3 by bolts which are at right angles to each other. The corner post 3 has T-slots formed during extrusion in the same way as the end rafter 2. The other flanges on the rafters 2 and corner posts 3 are for supporting conventional glazing clips etc. The abutment portion 34 is shaped to close off the end of the gutter and the use of the screw connection ensures a good seal at the end of the gutter.An aperture is formed in the abutment portion to allow rain water to flow out and an integrally formed hollow spigot 37 surrounding the aperture allow the connection of either a drain hose, or a cover to block the hole.

Normally the drain hose would be used at one end of the gutter, the other end being stopped. A similar bracket of different hand is used at the other end of the gutter. In the bracket shown in Fig. 2a the vertical arm of the bracket is extended so as to include an extra bolt hole 38 and the bolt inserted through that hole may be used for connection of an oblique strut 7.

The joint shown in Fig. 4 is different from the two previously described in that it is a junction between three glazing bars which lie in the same plane. The jointing bracket 50 used at this junction has two arms 51, 52, which each engage the end of respectively a wall post or door frame member 5 and a horizontal tie 6. A third arm 53 is engaged at an intermediate position on a rafter 2. Each of the arms 51, 52, 53 is connected to its respective frame member using a square headed bolt which engages, in a T-slot formed in the frame member, but the post 5 and horizontal tie 6 do not have the 900 angle bar configuration of the rafters and corner door posts, and the connection of the third arm 53 to the rafter 2 is at only one side of the latter's angle bar configuration.Therefore the connection cannot be by use of two bolts at 900 as in the previous joints, and the special feature of the bracket 50 is the way in which the individual connections are stiffened despite the single bolt connection. On each of the arms 51,52,53 of the bracket 50 the square headed bolt is flanked by integrally formed lugs or abutment surfaces 54, 55, 56. As seen more clearly in Figs. 4a, b and c, when the connection is complete, the lugs and abutment surfaces embrace the outer walls of the T-slot (Fig. 4a!, additional flanges parallel to the Tslot (Fig. 4b) or a combination of the two (Fig. 4c).

In this way any tendency of the frame members to pivot about the bolted connection is resisted. It will be appreciated that this stiffening feature could also be applied to the arms of the brackets shown in Figs. 2 and 3 or to any junction where two or more frame members are connected to a jointing bracket by a T-slot/bolt combination.

It can be seen from the foregoing that each of the brackets described above serves to increase the rigidity of the greenhouse framework to the extent that it is possible for the framework to stand erect without the use of oblique support struts. As a matter of sound practice, the greenhouse shown in Fig. 1 does still include such oblique support struts to ensure adequate strength of the framework when under load from the weight of glass and wind loading etc. However the fact that the initial framework can stand along is of great assistance during assembly of the framework. Assembly is also assisted by the various features described above for ensuring accurate location of the various frame members on their respective brackets.

In the preferred forms of the brackets shown above they are die cast from a zinc alloy. However brackets that incorporate the general concepts set out above can readily be fabricated from machined or stamped metal parts or folded from sheet metal. Alternatively, suitable brackets can be moulded or machined from plastics such as nylon.

Also while the frame members are conveniently extruded from light-weight alloys so as to form the various axial slots and flanges, the joints described above are equally applicable to frame members fabricated in other ways, such as folding from sheet metal. Again plastics can be used if desired, for example by extrusion of PVC.

Claims

1. A greenhouse frame in which a first frame member having two outspread flanges with an included angle of less than 1 800 is bolted to a jointing bracket and two further frame members are bolted to respective arms formed on the bracket with the same included angle.

2. A greenhouse frame according to claim 1 in which the first frame member is a ridge member having two elongate outspread flanges set at the roof angle, and the two further frame members are a pair of rafters.

3. A greenhouse frame according to claim 1 in which the first frame member is an eaves member having two outspread flanges set at the eaves angle and the two further frame members are a wall post and a rafter.

4. A greenhouse frame according to claim 1, 2 or 3, in which the flanges of the first frame member are bolted to extensions of the bracket arms which project along the main axis of the first frame member and the bolts connecting the first frame member to the bracket and the bolts connecting the further frame members to the bracket are spaced from each other in the direction of the main axis of the first frame member.

5. A greenhouse frame according to any one of claims 1 to 4 in which the first frame member is located against an abutment portion formed on the bracket at the junction of the two arms at right angles to the main axis of the first frame member and the first frame member is secured to the abutment portion.

6. A greenhouse frame according to claim 5 in which the first frame member is a metal extrusion including an axially extending screw groove and the first frame member is secured to the abutment portion of the bracket by a self-tapping screw passed through the abutment portion and engaged with the screw groove.

7. A greenhouse frame according to any one of claims 1 to 6 in which the two further frame members are metal extrusions including an axially extending T-slot and the frame members are bolted to their respective bracket arms by a bolt whose head is located in the T-slot, the arms having lugs and/or abutment surfaces which embrace the T-slot and engage the outer walls of the T-slot or other protrusions or flanges on the frame member.

8. A greenhouse frame in which a first frame member is connected to a jointing bracket having two arms set at an included angle of less than 1 80C and an abutment portion extending at right angles across the main axis of the first frame member, the first frame member being located against and secured to the abutment portion and also bolted to the bracket at or near the junction of the arms, and two further frames are bolted to respective arms of the bracket.

9. A greenhouse frame according to claim 8 in which the first frame member is a ridge member having a substantially channel-shaped or hollow cross-section with an open end which closed by the abutment portion and the two further frame members are a pair of rafters.

10. A greenhouse frame according to claim 8 in which the first frame member is an eaves member having a gutter section with an open end which is closed by the abutment portion and the two further frame members are a wall post and a rafter.

11. A greenhouse frame according to any one of claims 8 to 10 in which the first frame member is a metal extrusion including an axially extending screw groove and the first frame member is secured to the abutment portion of the bracket by a self-tapping screw passed through the abutment portion and engaged with the screw groove.

12. A greenhouse frame according to any one of claims 8 to 11 in which the two further frame members are metal extrusions including an axially extending T-siot and the frame members are bolted to their respective bracket arms by a bolt whose head is located in the T-slot, the arms having lugs and/or abutment surfaces which embrace the T-slot and engage the outer walls of the T-slot or other protrusions or flanges on the frame member.

1 3. A greenhouse frame according to any one of claims 8 to 12 in which the first frame member is bolted to the bracket at or near the junction of the two arms.

14. A greenhouse frame in which two or more frame members are connected to a jointing bracket and at least one frame member is a metal extrusion including an axially extending T-slot which is bolted to the bracket by a bolt whose head is located in the T-slot, bracket having lugs and/or abutment surfaces which embrace the T-slot and engage the outer walls of the T-slot or other protrusions or flanges on the frame member.

1 5. A greenhouse frame according to claim 14 in which three frame members are connected to the bracket.

16. A greenhouse frame according to claim 1 5 in which two of the frame members lie in the same plane and the main axis of the third frame member is at right angles to that plane.

1 7. A greenhouse frame according to claim 1 5 in which the three frame members lie in the same plane, two being connected at an end, the other at a point along its length.