GB2080529A

GB2080529A - Hand-grip Bushing Assembly or Enclosed Hollow Sections

Info

Publication number: GB2080529A
Application number: GB8121895A
Authority: GB
Original assignee: ULLRICH STABILA MESSGERAETE
Current assignee: ULLRICH STABILA MESSGERAETE
Priority date: 1980-07-17
Filing date: 1981-07-16
Publication date: 1982-02-03
Also published as: DE3027123A1; AT375464B; FR2486854A1; DE3027123C2; CH652962A5; FR2486854B1; GB2080529B; ATA240781A

Abstract

A hand-grip bushing assembly for devices having enclosed hollow sections e.g. spirit levels comprises two hand-grip bushing halves (5, 5'), which are inserted in a respective one of two mutually aligned openings (3) on opposite sides of the hollow section, and are attached to each other by means of a tongue and groove system (9, 10, 12, 13, 14) inside the hollow section (1). The hand-grip bushing halves may be in the form of bottomless troughs, whose peripheral rim (6) abuts the outside of the wall of the hollow section, and whose side walls (8), which extend inside the hollow section, interlock to form a seal by means of a groove (9) on one half (5') of the bushing and a tongue (10) on the other half (5') of the bushing. <IMAGE>

Description

SPECIFICATION Hand-Grip Bushing Assembly for Enclosed Hollow Sections The present invention relates to a hand-grip bushing assembly for enclosed hollow sections, in particular the hollow section of a spirit level, whuch assembly is inserted in openings in the walls of the enclosed hollow section.

Spirit levels in particular, comprise an elongate chassis of rectangular, I- or similar shaped section. The actual spirit levels, i.e. bubble units, are appropriately mounted in this chassis. The chassis may be made of wood, cast metal (preferably a light metal) or drawn sections.

Extruded, rectangular-section tubes, in the form of enclosed light-metal hollow sections, have proved particularly advantageous for this purpose. Such rectangular-section tubes have the advantage of very light weight combined with substantial stiffness. In addition, they provide favourable conditions for the rigid, secure mounting of the bubble units, and can be manufactured to the necessary standard of accuracy at favourable cost.

The only disadvantage which these spirit-level chassis comprising extruded rectangular-section tubes have compared with known cast spirit-level chassis generally in the form of a frame of Ishaped section, whose web has a central opening, is that they cannot be held by placing the hand through them, as in the case of these latter. This, however, is a particularly effective method of handling in practice, since it enables the spirit level to be held firmly in the hand without hindrance to its application to the component to be levelled.

It is also known to provide such through hand grips in spirit levels made of wood, and from rectangular-section metallic tubes, by milling out elongate slots at suitable points in the centre of the chassis. Since these slots are disposed in the vicinity of the neutral zone of the section, the spirit-level chassis are not thereby substantially weakened.

When this method is used for rectangularsection tubes, however, correspondingly sharp edges are formed on the inner sides. Moreover, access to the interior of the section is thereby opened up, so that dust is able to accumulate, and can only be removed with difficulty. For this reason, according to known practice, these through hand grips are sealed by means of handgrip bushings which are inserted in the milled-out slots. Single-piece embodiments of such handgrip bushings are known, which are manufactured from relatively resilient plastics material and can be snapped into the slots. This method of attachment is, of course, simple, but is by nature insufficiently secure. Moreover, for such an application it is necessary to have recourse to a relatively soft, resilient material for manufacture of the hand-grip bushings, in order to enable the bushings to be correctly inserted.However, such material has the disadvantage of undesirable deformation of the bushings, and consequently the risk of the bushings falling out of the openings.

The aim of the present invention is therefore to create a hand-grip bushing suitable for such enclosed hollow sections, which can not only be easily inserted, but also securely retained, in the corresponding openings.

According to the present invention, there is provided a hand-grip bushing assembly for enclosed hollow sections, which assembly is inserted in opposed openings in the walls of the hollow section, said assembly comprising two hand-gripbushing halves which, in use, are inserted from opposite sides in a respective one of two mutually aligned openings in said hollow section, the hand-grip bushing halves incorporating a tongue and recess system for use in joining the hand-grip bushing halves together inside the said hollow section.

The halves of the divided hand-grip bushing can be particularly easily inserted in the openings in the hollow section from the outside, without the necessity to use a particularly soft material for this purpose. The two halves are rigidly attached to each other inside the hollow section, effectively sealing the latter, in such a manner that the bushings are reliably prevented from working loose and falling out of the openings. At the same time, the material may be relatively rigid. The fastening elements are completely enclosed by the enclosed hollow section, so as to render them invisible from the outside. They fully seal the section, and, after assembly, the hand-grip bushings can be removed only by destroying them.Preferably, the hand-grip bushing halves overlap each other in the manner of a tongue and groove joint inside the hollow section, so that tight sealing of the hollow section is thereby ensured. In addition, pins engage in corresponding recesses, so that, by this additional means, the hand-grip bushings inserted in the hollow section can be securely and inseparably joined together.

These fastening elements are so arranged symmetrically on each half of the hand-grip bushing that both the male and the female parts of the fastening elements are symmetrically distributed about one and the same half of the bushing. This ensures that both halves of the hand-grip bushing are completely identical in shape.

In one embodiment of the present invention the pins and sockets are of matching conical configuration and the pins are an interference fit in the sockets. This provides a firm abutment with any section, even when the latter exhibits substantial tolerances in width. Clamping of the hand-grip bushing halves in the section is effected in such a manner that deformation is substantially prevented.

In order to prevent the relatively long and thin side walls from bending inwardly under stress and then spring out of the opening, projections are preferably formed on the side of the side wall of the hand-gripbushing halves which face inside the hollow section, in the region of the transition to the peripheral rim, which projections engage in correspondingly formed notches in the openings.

Preferably the projections are integrally formed with the sockets and pins and are trapezoidal in shape, the notches being of complementary dovetail shape. These features improve the interlocking of the projections and the notches.

Preferably the hollow section is provided externally with reinforcing ribs flush with the peripheral rims of the inserted hand-grip bushing halves. In order to avoid gaps between these reinforcing ribs and the peripheral rim of the hand-grip bushing halves, the latter may be formed so as directly to abut each other, so that the overall homogeneity of the device is not prejudiced.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a crosssectional view along the line I-I of a spirit-level chassis provided with a handgrip bushing assembly according to the present invention; Fig. 2 is a side-elevational view of a spirit-level, in which, in the left-hand half, the upper hand-grip bushing is removed, and a longitudinal sectional view of the spirit-level chassis, and Fig. 3 shows a variant of the method of fastening the hand-grip bushings.

Figs. 1 and 2 of the accompanying drawings show the present invention as applied to a spiritlevel chassis 1, in the form of an enclosed hollow section, which, in the case now under consideration, is a rectangular-section tube with a longitudinal ribs 2 extending externally along the narrow sides, one or more oval openings 3 being provided in the sides 7 of said tube. A plurality of dovetail notches 4 are arranged at certain intervals in the rims of these openings 3, 3'.

One half 5, 5' of a hand-grip bushing according to the present invention is inserted from the outside in a respective opening 3, 3', the handgrip bushings being each in the form of bottomless troughs-as viewed in Fig. 2. As the openings 3,3' are effectively aligned with each other, the halves 5, 5' of the hand-grip bushing are also aligned with each other when inserted in openings 3, 3', a toroidal peripheral rim 6 of said halves 5, 5' abutting the sides 7 of the rectangular-section tube, while the side walls 8 of the hand-grip bushing halves seal access via the opening 3, 3' to the interior of the tube section.

One half of the bottom edge of the side walls 8 is provided with a groove 9, and the other half is provided with a tongue 10. On assembly, the tongue 10 of one bushing half engages in the groove 9 of the other bushing half, and thereby seals the gap 11 which is formed between the hand-grip bushing halves 5, 5' when the width of the tube section exceeds the depth of the two side walls 8 together. The depth of the side walls 8 is so selected that the latter just touch each other when the width of the section is at its minimum limit of tolerance. The width of the gap 11 then corresponds to the actual width of the section used.

One or more pins 12 are mounted on each half 5, 5' of the hand-grip bushing and extend from one half bushing beyond the side wall 8 of that half bushing, to engage in a bore 14 in an enlarged region 13 of the other half bushing.

Preferably, each half of the hand-grip bushing is provided on one symmetrical half of the periphery of the side wall, with pins, and on the other symmetrical half of the periphery of the same side wall, with matching sockets. This simplifies manufacture, the bushing halves being then identical. The pins 12 are preferably conical in shape, and are in interference fit in the bores 14.

On assembly, the pins 12 are press-fitted in the bores 14, the depth of their insertion being variable in order to match variations in the width of the tube section. They are secured in this position owing to their being in the form of known grooved pins, or to their being subjected to ultrasonic radiation on their insertion in the bore 14, whereby they are welded in the bore, or to the bores 1 4 being treated with a suitable adhesive substance prior to the insertion of the pins 12.

Alternatively, it is possible to manufacture pins and bores in the form of a snap fastening. An enlarged-scale view of the fastening elements of one form of suitable snap fastening, in the disassembled state, is shown in Fig. 3.

Correspondingly, the sockets 13, 14 of the abovedescribed embodiment (Figs. 1 and 2) are in the form of at least two strip-like jaws 1 3', between which there is formed an elongate gap 14'. Over a limited end portion, the mutually opposed inner sides of the jaws 13' are provided with saw-tooth profiling 1 6. The pin 12', which forms the companion part of the fastening, is of a size corresponding to the gap 14', and is provided with corresponding saw-tooth profiling 1 7 over a portion of similar length.

The saw-tooth profiling is transversely oriented, so that the pin 12' is insertable in the gap 14' in such a manner that the saw-tooth profiling 17 of the pin 12' slides in the manner of a ratchet over the saw-tooth profiling 1 6 of the strips 1 3' and, corresponding to the pitch of the saw teeth, so engages with the latter, in the manner of a detent mechanism, that it is impossible to withdraw the pin 12'. Subsequent loosening of the interconnected hand-grip bushings 5, 5' is thereby rendered impossible without destroying the hand-grip bushings themselves. The distance the pin 12' can be inserted, and locked, in the gap 14' between the strips 13' can be varied in order to match variations in the spirit-level chassis section. In order to permit the saw-tooth configurations to slide one into the other in the manner of a ratchet, the strips 1 3' are of flexible construction, so that they are able to move relative to each other when subjected to elastic deformation. Should the outer rim 6 of the hand-grip bushings 5, 5' abut the sides 7 of the spirit-level chassis (1) without interlocking of the transverse faces of the saw teeth taking place, the hand-grip bushing halves can move at most one tooth pitch apart. If the pitch is correspondingly small, the distance between the rim 6 of the hand-grip bushing halves 5, 5' and the side 7 of the spirit-level chassis 1 is, practically speaking, insignificant, and equivalent to a close fit.

The saw teeth of the saw-tooth configurations 1 6 and 1 7 substantially match each other dimensionally, so that the teeth of the configuration 1 7 of the pin 12' are able to engage in the transverse grooves formed between the teeth of the configuration 1 6 of the strips 13'. The tips of the saw-teeth of the configuration 1 7 of the pin 12' are blunted. The degree of bluntness increases in a direction towards the free end of the pin 12'. This permits the pin 12' to be inserted in the gap 14 with less frictional resistance, the oblique faces of the leading teeth 1 8 of the pin 12' forcing apart the corresponding oblique faces of the leading teeth 1 9 of the strips 13'.Furthermore, blunting of the teeth permits closer engagement of the saw teeth in the cavities between the saw teeth of the strips 13'.

In other respects, the fastening elements of this type are arranged on the hand-grip bushing halves in an identical manner to the fastening elements described with reference to Figures 1.

and 2.

In order to prevent the relatively long and thin side walls 8 from bending inwardly under stress, and then possibly springing out of the openings 3, ribs 1 5 are arranged in the configuration of a V in the region of the pins 12 and the enlarged region 13. When the hand-grip bushing halves are inserted from the side, these ribs 1 5 engage from the inside with the sides of the dove-tail notches 4 in the spirit-level chassis, and thereby rigidly attach the side walls 8 of the hand grip bushing halves to the sides 7 of the spirit-level chassis.

Such hand-grip bushing fastenings can be fitted not only to a spirit-level chassis, but also to any articles manufactured from hollow sections which have parallel side walls, such as straightedges, smoothing boards, measuring staffs, and such like.

Claims

1. A hand-grip bushing assembly for enclosed hollow sections, which assembly is inserted in opposed openings in the walls of the hollow section, said assembly comprising two hand-grip bushing halves which, in use, are inserted from opposite sides in a respective one of two mutually aligned openings in said hollow section, the handgrip bushing halves incorporating a tongue and recess system for use in joining the hand-grip bushing halves together inside the said hollow section.

2. A hand-grip bushing assembly as claimed in claim 1, in which the hand-grip bushing halves are each in the form of bottomless troughs, whose peripheral rim, in use, abuts the outside of the hollow section provided with the respective opening, and whose side walls, which, in use, extend inside the hollow section, interlock to form a seal, owing to the formation of a groove on one half of the hand-grip bushing, and the formation of a tongue on the other half of the hand-grip bushing.

3. A hand-grip bushing assembly as claimed in claim 2, in which each half of the hand-grip bushing is provided on one symmetrical half of the periphery with a recess, and, adjoining it, on the other symmetrical half of the periphery, with a matching tongue.

4. A hand-grip bushing assembly as claimed in at least one of claims 1 to 3, in which on the side of the side wall of one half of the hand-grip bushing facing inside the hollow section, there are formed one or more pins, which extend in a direction towards the other half of the hand-grip bushing, and, in this direction, along the corresponding side wall, engage in sockets which are shaped to match the shape of the pins and are formed on the side of the side wall of the other half of the hand-grip bushing which faces inwardly inside the hollow section.

5. A hand-grip bushing assembly as claimed in claim 4, in which each half of the hand-grip bushing is provided on one symmetrical half of the periphery of the side wall with the pins, and on the other symmetrical half of the periphery of the same side wall with the matching sockets.

6. A hand-grip bushing assembly as claimed in claim 4 and/or 5, in which the pins and the sockets are of matching conical configuration, and the pins are an interference fit in the sockets.

7. A hand-grip bushing assembly as claimed in at least one of claims 4 to 6, in which the pins are a press fit in the sockets.

8. A hand-grip bushing assembly as claimed in at least one of claims 4 to 6, in which the pins are in the form of grooved pins.

9. A hand-grip bushing assembly as claimed in at least one of claims 4 to 6, in which the pins are ultrasonically welded in the sockets.

1 0. A hand-grip bushing assembly as claimed in at least one of claims 4 to 6, in which the pins are adhesively secured in the sockets.

11. A hand-grip bushing assembly as claimed in claim 4, in which the sockets comprise strips which are resiliently movable in a direction towards or away from each other, and which form between them a gap, the inner end portions of these strips being provided with a saw-tooth profile, such that the surfaces of the teeth which extend at an angle with respect to one another are so oriented transversely to the longitudinal direction of the strips that oblique surfaces, and surfaces disposed at right angles to the longitudinal direction of the strip, alternate with each other from the free end of the strips inwardly in the longitudinal direction of the strips, and the pin is provided with a corresponding sawtooth profile, whose oblique surfaces and surfaces at right angles to the longitudinal direction of the pin alternate with each other from the free end inwardly in the longitudinally direction of the pin.

12. A hand-grip bushing assembly as claimed in claim 11, in which the tips of the saw teeth of the saw-tooth profiling of the pin ere blunt.

13. A hand-grip bushing assembly as claimed in claim 12, in which the saw teeth are increasingly biunt in a direction towards the free end of the pin.

14. A hand-grip bushing assembly as claimed in at least one of claims 1 to 13, in which, on the side of the side wall of the halves of the hand-grip bushing facing inwardly inside the hollow section, in the transition region leading to the peripheral rim, projections are formed, which engage in matching notches in the said openings.

1 5. A hand-grip bushing assembly as claimed in claim 14, in which the projections are integrally formed with the sockets or the pins.

16. A hand-grip bushing assembly as claimed in claim 14 and/or claim 15, in which the projections are trapezoidal in shape and diverge in a direction away from the side wall, and the notches are of matching dovetail, shape.

1 7. A hand-grip bushing assembly as claimed in claim 14 and/or 15, in which two projections are provided which extend outwardly from the said side wall and are disposed in the form of a V relative to each other in order to form the shape of a trapezium.

18. A hand-grip bushing assembiy as claimed in claim 17, in which the notches in the wider rim thereof are provided with an extension which extends between the V-formation projections.

19. A hand-grip bushing assembly as claimed: in at least one of claims 1 to 18, in which the hollow section is provided externally with reinforcing ribs arranged flush with the periphery rim of the inserted hand-grip bushing halves.

20. A hand-grip bushing assembly for enclosed hollow sections, which assembly is inserted in opposed openings in the walls of the hollow section, said assembly being constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.