GB1582382A

GB1582382A - Castor mounting means

Info

Publication number: GB1582382A
Application number: GB3019577A
Authority: GB
Original assignee: Global Castors and Hardware Ltd
Current assignee: Global Castors and Hardware Ltd
Priority date: 1978-05-08
Filing date: 1978-05-08
Publication date: 1981-01-07

Description

(54) CASTOR MOUNTING MEANS (71) We, GLOBAL CASTORS AND HARD WARE LIMITED, a British Company, of MAP Works, King Alfred Way, Cheltenham, Gloucestershire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to mounting means for castors or so-called "glides" and to castor or glide mounting assemblies, particularly in or for tubular furniture such as for example trolleys, television stands and office chairs.It is of general application to the mounting of a castor or glide adjacent one end of a tube member with a mounting spindle of the castor or glide disposed transversely of the longitudinal axis of the tube member, and for convenience the term "castor" is used hereinafter generally to mean "castor or glide".

Although applicable to the mounting of castors in tube members of any cross-sectional shape, the most usual shapes are either rectangular or with two flat side walls parallel to a major axis of symmetry of the section and joined through semi-circular side walls. The invention will be more particularly described hereinafter, by way of example, with reference to these two shapes the latter of which will for simplicity be referred to as an elongated rounded section.

Conventionally a castor is mounted adjacent one end of a tube member by drilling and tapping a mounting hole through a side wall of the member, and closing off the end of that member by driving in a blanking plug.

This involves the expense of tapping the mounting hole and providing a costly castor spindle which is screw threaded and has a locating shoulder to abut the tube member.

Furthermore, the blanking plug has to be of sufficient size to be a tight fit over the fairly wide dimensional tolerance which applies with the tube used in tubular furniture, so that more of ten than not when the plug is driven in excess material is shaved off by the cutting edge presented by the tube end, the attached shavings - being difficult to remove and any residual shavings detracting from the finished appearance.

Other arrangements have come into use employing an end plug with a solid body provided with a mounting bore for the castor spindle. This obviates the tapping operation and enables a cheaper spindle to be used, but it is still necessary for the plug to be a tight fit with the aforesaid shaving-off problem. Such arrangements are disclosed in Patent Specification Nos. 1,421,781 and 1,433,057.

The object of the invention is to provide mounting means and assemblies with which the major problems and disadvantages of the foregoing arrangements are materially overcome, and which are cheaper to manufacture and assemble.

According to one aspect of the invention means for mounting a castor on a tube member having a side hole adjacent one end thereof for insertion of a castor mounting spindle comprises a moulding adapted to be inserted into the end of the tube member to blank off the end opening thereof and having a hollow spindle mounting portion, and a tubular spindle mounting ferrule with a bore to receive the castor spindle and adapted to be fitted through said hole and forced into said mounting portion of the moulding with resultant expansion of the latter whereby the moulding frictionally engages the tube member to fix the moulding firmly therein.

Thus the invention provides a mounting which in particular overcomes the disadvantage referred to of the previously proposed solid plugs. The moulding, which is preferably of plastics material, does not have to be a tight fit in the tube member and in fact on insertion need contact the inner surface over a relatively small area, so that the shaving-off problem is no longer present.

Preferably the frictional engagement with the tube member utilises the feature that the tube sections used have radiused portions so that they are of decreasing internal depth towards the side walls of the tube. Thus a rectangular section tube has in each corner a small radius through which the upper and lower walls join the side walls, considering said mounting hole as being drilled in the lower wall of the tube, and the elongated rounded section tubes referred to have semicircular top and bottom walls.It is a preferred feature of the invention that said mounting portion of the moulding should be a free fit on insertion in the end of the tube with a spacing with respect to the side walls thereof and a fairly close fit between the upper and lower walls, so that the resultant lateral expansion of the mounting portion as the mounting ferrule is forced therein causes the mounting portion to engage and ride up said internal radiused portions of the tube whereby frictional engagement with the tube includes a wedging component. It will be appreciated that the expansion of the mounting portion may be sufficient to provide also a frictional grip with the side walls of the tube, but this is not essential and the wedging friction between the mounting portion and the radiused portions of the tube may be relied on to fix the moulding firmly within the tube member.

The mounting portion of the moulding may be of plain hollow cylindrical form and it may be spaced from an outer flange portion, which closes off the end of the tube member, by a flexible interconnecting portion so that the moulding can flex as the ferrule is fitted therein and thus allow a considerable tolerance in the predrilling of the hole in the tube member. Thus, applying a positive tolerance to the positioning of that hole, referring to its spacing from the end of the tube member, ensures that the flexing holds the flange portion firmly against the end of the member and the latter portion can be in the form of a simple end plate.The flexible interconnecting portion may comprise an arrangement of thin webs which engage the tube member for location purposes, also providing the required flexibility with a moulding which uses a relatively small volume of moulding material as compared with the prior solid end plugs, thereby enabling better quality plastics material to be used while the production cost per moulding is even so much less.

The ferrule is preferably also a plastics moulding, conveniently with an end flange which locates against the bottom side wall of the tube member and which provides a bearing against which the castor body can turn. The spindle mounting bore in the ferrule is preferably moulded with an inward projection or projections, for example an annular rib, to engage a peripheral groove in the spindle for retention of the latter and to provide snap-in fixing of the castor spindle.

This provides an additional advantage with respect to the solid plugs previously used and which have required additional fixing means, such as a spring ring, or merely employed a friction grip to retain the spindle.

According to another aspect the invention provides a castor mounting assembly com prising a tube member having a side hole adjacent one end thereof for insertion of a castor mounting spindle, said tube member having a cross-sectional shape including radiused portions such that the depth of the tube decreases towards side walls of the tube section, a plastics moulding fitted into said end of the tube to blank off the end opening therein and having a mounting portion which extends between the upper and lower walls of the tube section, and a mounting ferrule with a bore adapted to receive the mounting spindle of the castor and fitted into the moulding portion through said tube hole, the ferrule being forced into tithe moulding portion whereby to expand the latter laterally so that an upper and/or lower surface thereof engages corresponding radiused portions of the tube section to provide a frictional wedg ing force which fixes the moulding firmly within the tube member. Preferably the mounting portion has both upper and lower frictional wedging engagement with the tube member and is initially a free sliding fit so that the moulding can readily be inserted into the tube member by hand.

Furthermore, the invention includes such an assembly with a castor fitted therein, and tubular furniture with a plurality of such assemblies for mounting supporting castors.

Broadly speaking, the invention according to a further aspect comprises a method of mounting a castor or glide in a side hole in a tube member adjacent one end thereof, including the steps of inserting a moulding into said one end of the tube member to blank off the end opening therein, and sub sequently inserting a ferrule adapted to re ceive a mounting spindle of the castor or glide through said tube side hole into the moulding, the insertion of the ferrule expand ing the moulding laterally of the tube to effect wedging frictional engagement of the mould ing with internal radiused or inclined portions of the tube section whereby to fix the mould ing firmly within the tube.

Preferred embodiments of the invention which are also described in our co-pending Application No. 30196/77 (Serial No.

1582383) are illustrated in the drawings accompanying the provisional specification and will now be described, by way of example, with reference thereto. In the drawings: Figure 1 is a side view of a mounting assembly in accordance with the invention including a tube member of flattened rounded section, this member being cut away and sectioned over an end region to show internal detail; Figure 2 is a top view of a main moulding of the assembly of Figure 1; Figure 3 is a sectional view on the line HI III in Figure 1; 'Figure 4 shows another mounting assembly induing a rectangular-section tube member and in end view looking along the tube member from the other end thereof; and Figures 5 and 6 are respectively side and end views of the main moulding of the assembly of Figure 4.

In each case the assembly comprises the main plastics moulding 1, the tube member 2 and a moulded plastics spindle-mounting ferrule 3. The moulding 1 has three primary portions; namely an outer end flange portion 4, a spindle mounting portion 5 and an interconnecting portion 6. The portion 4 is in the form of a flat end plate which abuts the end bf the tube member 2, the peripheral profile of this plate being identical with the outer shape of the tube member 2 to close off the latter in a smooth and aesthetically pleasing manner. The mounting portion 5 is of plain hollow cylindrical shape, providing an inner mounting bore 7 disposed laterally of the longitudinal axis of the tube member and defining a castor spindle mounting axis 8 lying in a central plane of symmetry of the tube section.The portion 6 comprises two thin webs 6a and 6b, the web 6a lying in said central plane which is vertical with a mounted castor in operative position and the web 6b lyirig at right angles thereto. Both webs extend inwardly beyond the mounting portion 5.

The ferrule 3 is of plain hollow cylindrical form, with a stem 9 which is a tight drive fit in the mounting portion 5 and which passes as a free fit through a predrilled hole 10 in the lower side wall 20 of the tube member 2, and a lower end flange 11 which locates against the member 2. As can be seen in Figure 3, the ferrule 3 has an inner cylindrical bore 12 which receives a castor spindle 13 as a free sliding fit, and the flange 11 has a lower thrust surface 14 which provides a bearing for the castor body 15. Only the adjacent portions of the castor spindle 13 and body 15 are shown in the drawing.The ferrule 3 has an upper end wall 16 which limits insertion of the spindle 13 when the latter is fitted, and internal moulded projections 17 engage a peripheral groove 18 in the spindle 13 to retain the spindle and provide snap-in fitting of the latter into the mounting assembly 1, 2 and 3.

In the first embodiment of Figures 1 to 3, the tubular mounting portion 5 is considerably narrower than the overall internal width of the tube member 2 but the upper and lower ends of that portion engage the semicircular upper and lower walls 19 and 20 of the member 2.

The semi-circular shape of the upper and lower walls 19 and 20 provides radiused portions of the tube section which results in a decreasing depth thereof towards the tube section side walls 23, 24. The initial dimensions of the moulding 1 are such that the tubular mounting portion 5 when inserted is a close but free sliding fit between the upper and lower walls 19, 20. As the ferrule 3 is forced into the mounting portion 5 it expands the latter laterally, with the result that the upper and lower ends of the portion 5 ride up said radiused portions of the tube section. Thus the mounting portion 5 engages the tube member 2 with a frictional wedging force which is considerable and which firmly fixes the moulding 1 in the end of the tube member 2.

The upper edge of the central web 6a also contacts the upper tube wall 19 for location purposes, and at its bottom edge the web 6a engages the lower tube wall 20 immediately adjoining the flange portion 4 where it has a short section 21 slightly inclined to the longitudinal axis to provide a lead. This bottom edge is then cut away to leave a free space s between a lower end section of the mounting portion 5 and the flange portion 4, and thereafter continues at an increased inclination over length 22 to the inner end of the moulding 1 at which it meets the inner end of the web 6b.

The web 6b is positioned at a height to engage the parallel side walls 23, 24 of the tube member 2 just below the upper wall 19, and to this end it has parallel side edges 25 which extend from the flange portion 4 to a point level with the inner side of the bore 7.

Thereafter these edges continue at 26 with an inward inclination to the inner end of the moulding 1.

The later embodiment of Figures 4 to 6 differs from that of the earlier figures in two major respects, to suit the different crosssection of the tube member 2. The first difference is that the mounting portion 5 substantially fills the internal cross-section of the tube member 2, as can be seen in the view of Figure 4, so that the upper and lower ends of the portion 5 engage the internal radiused corners of the rectangular tube section. As with the first embodiment the portion 5 is initially a close but free sliding fit between the upper and lower walls 27, 271 of the tube member 2, but in this case with only a small lateral clearance with respect to the side walls 28, 29.The resultant lateral expansion of the portion 5 as the ferrule 3 is inserted causes the upper and lower ends of the portion 5 frictionally to engage the internally radiused corners of the tube section with a wedging action. Thus in both embodiments the invention utilises lateral expansion of the moulding 1 resulting from insertion of the ferrule 3 to produce wedging frictional engagement with radiused portions of the tube section to fix the moulding firmly within the tube member 2.

The second difference is that the horizontal web 6b now lies flat against the upper wall 27 of the tube member 2, with its parallel side edges 30 again contacting the side walls 28 and 29. To accommodate the internal radius at the inner corners of the tube section, the edges 30 have an upper chamfer at 31. The edges 30 extend inwardly from some distance beyond the mounting portion 5, and then as before continue with an inward inclination at 32 to the central web 6a which they meet at the inner end of the moulding 1.

The ferrule 3 is unchanged, as is the bottom edge shape of the web 6a with inclined edge sections 21 and 22 offset to leave a clear space S between the mounting portion 5 and the flange portion 4.

In each embodiment the web formation 6a, 6b of the interconnecting portion 6 provides sufficient rigidity with adequate location in the tube member 2 while, particularly in view of the free space S, flexing to allow relative movement of the portions 4 and 5 as the ferrule 3 is driven through the hole 10 into the bore 7 of the portion 5. Thus a considerable tolerance is allowed for positioning of the hole 10, and the flexing produces a resilient force holding the outer end flange 4 firmly against the end of the tube member 2 without the necessity of the moulding 1 initially being a tight fit in the tube member 2.

In a typical example where the nominal dimension A (Figures 1 and 2) between the hole 10 and the tube end is 12-5 mm, the limits for this dimension in the assembly may be +0 and +0.5 mm, i.e. the final dimension being between 12-5 mm and 13-0 mm.

WHAT WE CLAIM IS 1. Means for mounting a castor or glide on a tube member having a side hole adjacent one end thereof for insertion of a mounting spindle of the castor or glide, comprising a moulding which is adapted to be inserted into the end of the tube member to blank off the end opening thereof and which has a hollow spindle mounting portion, and a tubular spindle mounting ferrule with a bore to receive the spindle and adapted to be fitted through said hole and forced into said mounting portion of the moulding with resultant expansion of the latter whereby the moulding frictionally engages the tube member to fix the moulding firmly therein.

2. Mounting means according to claim 1, wherein the moulding is designed so that the frictional engagement with the tube member when the ferrule is forced into said mounting portion utilises the feature that the tube section is of decreasing internal depth towards the side walls of the tube over radiused portions thereof.

3. Mounting means according to claim 1 or 2, wherein the moulding is dimensioned to be a free fit on insertion into the tube member with which it is designed to be used, with a spacing with respect to the side walls of the tube.

4. Mounting means according to claims 2 and 3, wherein the moulding is dimensioned to be a close fit between the upper and lower walls of the tube such that the resultant lateral expansion of the mounting portion as the mounting ferrule is forcd therein causes the mounting portion to engage and ride up said internal radiused portions of the tube whereby said frictional engagement with the tube includes a wedging component.

5. Mounting means according to claim 4, wherein said lateral expansion of the mounting portion is sufficient to provide also a frictional grip with the side walls of the tube.

6. Mounting means according to any one of the preceding claims, wherein said mounting portion of the moulding is of plain hollow cylindrical form.

7. Mounting means according to any one of the preceding claims, wherein said mounting portion of the moulding is spaced from an outer flange portion thereof, which flange portion is provided to close off the end of the tube member when the moulding is fitted therein, by a flexible interconnecting portion so that the moulding can flex as the ferrule is fitted therein whereby to allow a considerable tolerance in the predrilling of said hole in the tube member.

8. Mounting means according to claim 7, wherein said interconnecting portion is of webbed formation with webs which engage the tube member for location purposes.

9. Mounting means according to any one of the preceding claims, wherein the ferrule has an end flange for location against the tube member when the ferrule is forced into the mounting and to provide a bearing against which a body of the castor or glide can turn when the castor or glide is fitted.

10. Mounting means according to any one of the preceding claims, wherein the spindle mounting bore in the ferrule has an inwardfacing projection or projections to engage a peripheral groove in the spindle for retention of the latter and to provide snap-in fixing of the castor or glide.

11. Mounting means according to any one of the preceding claims, wherein said moulding is a plastics moulding.

12. Mounting means according to any one of the preceding claims, wherein said ferrule is a plastics moulding.

13. A castor or glide mounting assembly comprising a tube member having a side hole adjacent one end thereof for insertion of a mounting spindle of the castor or glide, said tube member having a cross-sectional shape including radiused portions such that the depth of the tube decreases towards side walls of the tube section, a plastics moulding fitted into said end of the tube to blank off the end opening therein and having a mounting portion which extends between the upper and lower walls of the tube section, and a mounting ferrule with a bore adapted to

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. and 29. To accommodate the internal radius at the inner corners of the tube section, the edges 30 have an upper chamfer at 31. The edges 30 extend inwardly from some distance beyond the mounting portion 5, and then as before continue with an inward inclination at 32 to the central web 6a which they meet at the inner end of the moulding 1. The ferrule 3 is unchanged, as is the bottom edge shape of the web 6a with inclined edge sections 21 and 22 offset to leave a clear space S between the mounting portion 5 and the flange portion 4. In each embodiment the web formation 6a, 6b of the interconnecting portion 6 provides sufficient rigidity with adequate location in the tube member 2 while, particularly in view of the free space S, flexing to allow relative movement of the portions 4 and 5 as the ferrule 3 is driven through the hole 10 into the bore 7 of the portion 5. Thus a considerable tolerance is allowed for positioning of the hole 10, and the flexing produces a resilient force holding the outer end flange 4 firmly against the end of the tube member 2 without the necessity of the moulding 1 initially being a tight fit in the tube member 2. In a typical example where the nominal dimension A (Figures 1 and 2) between the hole 10 and the tube end is 12-5 mm, the limits for this dimension in the assembly may be +0 and +0.5 mm, i.e. the final dimension being between 12-5 mm and 13-0 mm. WHAT WE CLAIM IS

1. Means for mounting a castor or glide on a tube member having a side hole adjacent one end thereof for insertion of a mounting spindle of the castor or glide, comprising a moulding which is adapted to be inserted into the end of the tube member to blank off the end opening thereof and which has a hollow spindle mounting portion, and a tubular spindle mounting ferrule with a bore to receive the spindle and adapted to be fitted through said hole and forced into said mounting portion of the moulding with resultant expansion of the latter whereby the moulding frictionally engages the tube member to fix the moulding firmly therein.

receive the mounting spindle and fitted into the moulding portion through said tube hole, the ferrule being forced into the moulding portion whereby to expand the latter laterally so that an upper and/or lower surface thereof engages corresponding radiused portions of the tube section to provide a frictional wedging force which fixes the moulding firmly within the tube member.

14. A castor mounting assembly according to claim 13, wherein said mounting portion has both upper and lower frictional wedging engagement with the tube member.

15. A castor mounting assembly according to claim 13 or 14, wherein said moulding is initially a free sliding fit for insertion into the tube member by hand.

16. A mounting assembly according to any one of claims 13 to 15 in combination with a castor or glide fitted therein.

17. Tubular furniture with a plurality of castor or glide mounting assemblies each in accordance with one of claims 13 to 15 for the mounting of supporting castors or glides.

18. A method of mounting a castor or glide in a side hole in a tube member adjacent one end thereof, including the steps of inserting a moulding into said one end of the tube member to blank off the end opening therein, and subsequently inserting a ferrule adapted to receive a mounting spindle of the castor or glide through said tube side hole into the moulding, the insertion of the ferrule expanding the moulding laterally of the tube to effect wedging frictional engagement of the moulding with internal radiused or inclined portions of the tube section whereby to fix the moulding firmly within the tube.

19. A castor or glide mounting assembly constructed by the method of claim 18.