GB2302015A

GB2302015A - Cap insert for tubular furniture feet

Info

Publication number: GB2302015A
Application number: GB9612044A
Authority: GB
Inventors: Gian Pearson
Original assignee: PROMOULD Ltd
Current assignee: PROMOULD Ltd
Priority date: 1995-06-10
Filing date: 1996-06-10
Publication date: 1997-01-08
Anticipated expiration: 2016-06-10
Also published as: GB9612044D0; GB9511826D0; GB2302015B

Abstract

A foot 22 having a threaded rod 18 is mounted to a tubular furniture frame 11 using a nut 19 held against rotation in a plastic insert 10 frictionally engaged in the end of the tube. The insert abuts the tube via cap 13 and has a bore 26 receiving the rod and a second bore 31 transverse to the first which holds the nut. In a second embodiment (Figs 1,2) the main bore (16) is transverse to the tube axis and the rod 18 passes through the side of the tube.

Description

A Means for Mounting Nuts in Tubinq The invention relates to inserts which are utilised for capping tubing and which have a screw threaded nut therein allowing a screw strut to be adjustably mounted in the capping. In particular, this invention relates to a method of attachment of feet to furniture constructed from tubular frames.

A typical office desk or table is made from a tubular metal frame to which the draws, vanity panels and top are secured. The metal frame may have downwards legs, which are fitted with feet for standing on the floor or other surface. These feet in the simplest form may comprise plastic moulded inserts which are a push fit into the frame. In more expensive furniture the plastic moulded inserts may be threaded and separate feet on adjustable screw struts are screwed into the inserts allowing the desk to be levelled should a floor surface be uneven.

A problem with moulding plastic inserts having a screw thread is that either the screw thread must be moulded into the plastic insert, or alternatively a screw-threaded nut, or stud, may be moulded into the plastic insert. In either case the cost is high. Plastic tools having screw thread forming parts are complicated and expensive because of the problem of removing the moulding from the screw thread former. Alternatively the placing of nuts or studs into a mould for integral moulding is time consuming and may cause tool damage if not correctly located.

The present invention provides a plastic insert for tubing in which a nut can be inserted after moulding, but before insertion into a tube.

Accordingly there is provided a cap insert for mounting a nut in tubing and which comprises a plastic moulded body for insertion longitudinally into an end of said tubing and which is an interference fit in said tubing, the body being formed with a first bore therein which in use accommodates a screw thread strut, and a second bore which can accommodate and retain against rotation a screw-threaded nut so that the centre of the nut is substantially in alignment with the first bore, the nut in use being held in position in the body by the tubing after insertion of the cap insert.

Preferably the second bore is perpendicular to the first bore , and the first bore is normal to the longitudinal axis of the tubing into which the cap is inserted.

Conveniently the second bore intersects the first bore so that the nut is closer to the end of the first bore that receives the screw-threaded strut than to the other end of the first bore.

Alternatively the first bore is co-axial with the longitudinal axis of the tubing and the second bore is also coaxial with the tubingand is located at the outer end thereof.

The insert, together with a nut insitu in the second bore, form a means of mounting a screw threaded adjustable foot onto the tubular frame of furniture, particularly commercial office furniture.

Also according to the invention there is provided a method of attaching a screw-threaded strut to an open ended tube, in which method a moulded plastic insert is manufactured to be a push fit into an open end of said tube and has a first bore adapted to receive the strut and a second bore adapted to receive a nut into which the strut can be screwed, the nut being pushed into the second bore to align with the first bore, and the insert with nut insitu is then pushed longitudinally into the tubing so that the tubing causes second bore to trap the nut in place, the strut then being screwed into the nut through the first bore.

The invention will be described by way of example and with reference to the accompanying drawings in which: Fig 1 is a sectional view through a cap insert insitu in tubing according to the present invention, Fig 2 is a section on the line II-II of Fig 1, Fig 3 is a section through a second embodiment of the invention, and Fig 5 is a section through a third embodiment of the invention.

With reference to Figs 1 and 2 there is illustrated a cap insert 10 which is for insertion into rectangular section tubing 11 of the type used for the construction of office furniture. The tube need not necessarily be of rectangular section for the performance of the invention.

The cap insert 10 is moulded, preferably by injection moulding, from a thermoplastic material, preferably a resilient material e.g. polypropylene or nylon such as nylon 6, nylon 66 etc, and is an interference fit in the mouth of the tube 11.. Ribs or serrations may be moulded into the outer surface of the insert to ensure that there is interference between the parts.

The cap insert 10 comprises a body portion 12 which is inserted longitudinally into the open end of the tube 11 and a larger dimension cap 13 which covers the exposed ends of the tube 11 and provides a shoulder 14 to limit the insertion of the body portion 12 into the tube 11. The body portion 12 has cavities 15, one in each flank adjacent the cap 13 to reduce the sectional thickness of the moulding and hence shrinkage problems during cooling.

There is a first blind bore 16 in the body portion normal to the longitudinal axis of the tube 11 and which aligns with an aperture 17 in the wall of the tube when the cap insert 10 is fitted to the tube. The first bore accommodates a screw-threaded strut 18 insertable into the first bore 16 through the aperture 17.

The screw-threaded strut 17 is held in a nut 19 into which the strut 18 is screwed. The nut 19 is located in a second blind bore 21 which is normal to the longitudinal axis of the tube 11 and to the first bore 16. The second bore 16 is a rectangular section bore which is dimensioned to accommodate a square or hexagonal nut across opposed flats and is deeper than the first bore 16 thereby forming a groove in the wall of the first bore. The width of the groove is such that the nut 19 is a push fit into the second bore.

The strut 18 may have a foot 22, a presser, or other device attached at its outer end.

Thus it can be seen that the cap insert provides an improved method of mounting a screw adjustable device to the end of a tube.

The nut 19 is merely pushed home into the second bore 21 so that it aligns with the first bore 16. The cap inert 10 with the nut insitu is then pushed into the tube 11 until the cap 13 abuts the end of the tube bringing the first bore 16 into alignment with the aperture 17 the tube and trapping the nut in position. The strut 18 is then screwed into the nut 19.

Fig 3 shows an alternative construction in which the strut 18 is coaxial with the tube 11. In this case the first bore 26 is arranged to be coaxial with the tube 11, an the second bore 31 normal to the axis of the tube 11.

In order to increase the amount of adjustment available for the strut it is advantageous for the nut 19 to be located nearer to the cap end of the insert.

Although the method has been described with particuiar reference to placing a nut in the cap insert, it may be utilised for placing a headed bolt or set screw into the inset prior to placing the insert into the tubing.

Yet another alternative embodiment is shown in Fig. 4in which the screw threaded strut 18 is arranged coaxially with the tubing 11. The cap insert 110 has a first bore 126 can be a blind bore or a through bore . The first bore 126 is coaxial with the tube 11 and the second bore is also coaxial with the tube and is located at the outer end thereof forming ashoulder 120 therebetween. The nut 19 is held in place by being a slight interference fit in the bore 131 which may be square or hexagonal to suit and sits against the shoulder 120.

The nut 19 is pushed into the second bore 131 until it sits against the shoulder 120. The cap insert 110 is then pushed into the end of a piece of tubing 11 and the interference therebetween causes the second bore 131 to distort to grip the nut 19 which is then held in position. In use the nut sits against the shoulder 120 to tramsmit loads through the tubing 11 to a adjustable foot 22.

Claims

1. A cap insert for mounting a nut in tubing and which comprises a plastic moulded body for insertion longitudinally into the open end of tubing and which is an interference fit in said tubing, the body being formed with a first bore therein which in use accommodates a screwthreaded strut, and a second bore to accommodate and retain against rotation a screw-threaded nut so that the centre of the nut is in alignment with the first bore, the nut being held in the second bore by insertion of the cap insert into the tubing

2. A cap insert as claimed in Claim 1 wherein the second bore is dimensional to receive a hexagonal nut across its flats, the nut being a. push fit into the second bore.

3. A cap insert as claimed in Claim 1 or Claim 2 wherein the first bore is normal to the longitudinal axis of the tubing into which the cap is to be inserted, and said second bore is also normal to said longitudinal axis.

4. A cap insert as claimed in Claim 1 or Claim 2 wherein said first bore is coaxial with the longitudinal axis of the tubing into which the cap is to be inserted, and said second bore is normal to said axis.

5. A cap insert as claimed in any one of Claims 1 to 4 wherein said second bore intersects the first bore so that the nut is located closer to the end of the first bore that receives the screw-threaded strut, than to the other end of the bore.

6. A cap insert as claimed in Claim 1 or Claim 2 wherein the first bore is coaxial with the tubing and the seconf bore is also coaxial with the tubing and is located at the outer end of the first bore with a shoulder therebetween.

7. A cap insert as claimed in any one of Claims 1 to 6 wherein said first bore is a blind bore.

8. A means of mounting a screw adjustable strut into tubing wherein said means comprise a cap insert as claimed in any one of Claims 1 to 7, and a nut inserted into said second bore, the screw strut being insertable into the first bore for screw engagement with the nut after insertion of the cap into the tubing.

9. Office furniture having at least one screw adjustable foot mounted in a tubular frame by means as claimed in Claim 8.

10. A method of attaching a screw threaded strut to an open ended tubing, in which method a moulded plastic insert is manufactured to be a push fit into an open end of said tubing and has a first bore adapted to receive the strut and a second bore adapted to receive a nut into which the strut can be screwed, the nut being pushed into the second bore to align with the first bore, and the insert with nut insitu is then pushed into the tubing so that the insertion of the insert into the tubing causes the nut to be trapped in place.

11. A method of attaching screw adjustable feet to a tubular support frame and in which method the feet are mounted on the frame by a screw strut attached by a method as claimed in Claim 10.