GB2169023A

GB2169023A - Bolts

Info

Publication number: GB2169023A
Application number: GB08529914A
Authority: GB
Inventors: Richard H Harvey; Peter Fellows
Original assignee: Paddock Fabrications Ltd
Current assignee: Paddock Fabrications Ltd
Priority date: 1984-12-04
Filing date: 1985-12-04
Publication date: 1986-07-02
Also published as: GB8430582D0; GB2169023B; GB8529914D0

Abstract

A bolt wherein a shoot 12 is slidable in a case 11 which is moulded in a synthetic resin material. The knob 13 of the bolt is rotatably mounted on the shoot 12 by snap fitting over a reduced radius portion 23 of the shoot. The case 11 has longitudinally extending ribs to frictionally engage the shoot. <IMAGE>

Description

SPECIFICATION Bolts This invention relates to slidable fastening devices of the kind known as bolts. The invention is principally concerned with barrel bolts but can find application in slide bolts and "necked" bolts also.

A widely used form of small barrel bolt has a cylindrical steel shoot slidable axially in an extruded aluminium case, one end of the bolt being co-operable in use with an extruded aluminium keep. Adjacent one axial end the shoot carries an operating knob, the knob extending radially outwardly from the shoot through a generally H-shaped slot in the wall of the case. The shoot is drilled radially to receive a fixing spigot of the operating knob, the fixing spigot being screw threaded or riveted into the shoot.In order to provide a satisfactory operating "feel" and to resist inadvertant axial movement of the shoot, for example as a result of vibration in use, the shoot is provided, at a point along its length which remains within the case during the operating movement of the shoot, with a radially extending blind bore within which is received a compression spring and a ball. The ball is urged radially outwardly by the compression spring to bear against the inner surface of the case, and thus provide a frictional drag giving the operating "feel" and a resistance to axial and angular movement of the shoot within the case.

The manufacture of this known form of bolt is subject to a number of disadvantages. The case, being formed as an aluminium extrusion, must be subject to further machining operations to cut it to length and to provide the X-shaped slot through which the operating knob extends and to provide holes for fixing screws. Further operations are necessary in order to provide the aluminium case with a decorative appearance and, for example, expensive anodising techniques may be needed.

The shoot itself as well as being cut to length must be cross-drilled to receive the knob and the spring and ball mechanism, and manual assembly is usually necessary to introduce the shoot equipped with the ball and spring into the case, and then to secure the knob to the shoot. A slide bolt differs from the barrel bolt described above in that the shoot, and the passage of the case and keep, are of corresponding non-circular cross-section, usually rectangular or D-section. However, the disadvantages mentioned above in relation to the known form of barrel bolt apply to known forms of slide bolts, and it is an object of the present invention to provide a bolt construction wherein these disadvantages are minimised.

A bolt in accordance with the present invention comprises a case having therein an axial passage slidably receiving a shoot, said case being moulded in a synthetic resin material.

Desirably the case is of a decorative colour.

Preferably the cross-sectional shapes of the passage of the case and said shoot are such that there are circumferentially spaced regions of contact between the wall of the passage and the shoot.

Preferably the wall of the passage of the case which slidably receives the shoot is formed with one or more integral ribs or protrusions engaging the shoot to provide an operating "feel".

Conveniently the wall of the passage receiving the shoot is formed with from 3 to 7 equi-angularly spaced axially extending integral ribs which engage the surface of the shoot.

Preferably the ribs are of part-circular crosssection.

Desirably the colour of the synthetic resin material used to form the case, and the colour of the shoot are different so as to provide a tonal contrast between the shoot and the case.

Conveniently the case carries a transversely movable locking device movable to engage and so resist axial movement of the shoot.

Desirably said device is a grub screw.

It will be recognised that the provision of the case as a synthetic resin moulding permits the use of coloured materials in the manufacture of the case so that without additional expense the case can be produced with a decorative appearance. Furthermore, because the case is moulded in a single operation no additional machining steps are necessary for example to cut the case to length or to provide the H-shaped slot in the case. This together with the relatively low cost of synthetic resin materials can result in a considerable cost saving over the conventional aluminium case.

A further disadvantage of the known barrel bolt construction described above is that when the shoot is in its operative position, that is to say protruding from the case and engaging in the keep, the case and the keep being on respective movable and fixed parts of the components to be locked, then the shoot has a very limited degree of rotational freedom within the case since the radially projecting knob of the shoot will engage opposite ends respectively of a limb of the H-shaped slot within which the knob moves. Thus in the event that an unauthorised intruder can insert a saw blade or the like between the fixed and movable components to try to saw through the shoot, then the sawing action will be facilitated by the shoot being positively held against rotation by the co-operation of the operating knob with the case.Slide bolts and "necked" bolts, where the shoot cannot rotate in the case suffer from the disadvantage that the knob cannot be used to lock the shoot in an operative position since the lack of rotation of the shoot relative to the case prevents such cooperation of the knob with the case.

It is an object of a second aspect of the present invention to provide bolts wherein these disadvantages are minimised. Boits in accordance with a second aspect of the invention may incorporate the features mentioned above in relation to the first aspect.

A bolt in accordance with a second aspect of the present invention includes an elongate shoot received in a case for axial movement relative thereto, and an operating knob which extends radially outwardly from the shoot, and which is engaged with the shoot in a manner resisting relative axial movement between the knob and the shoot, while permitting relative rotational movement of the knob and the shoot.

Preferably the shoot is formed with a circumferentially extending groove defining therein a neck of reduced diameter, and the knob includes a collar-like portion received in said groove and rotatably engaging said neck.

Desirably the outer surface of said collar-like portion is flush with the surface of the shoot.

Preferably said knob is moulded in a resilient synthetic resin material and is engaged as a snap-fit on said shoot.

Preferably said collar-like portion is split to facilitate its snap engagement in the groove of the shoot.

Preferably said knob extends from said shoot through a generally H-shaped slot in the wall of said case, the circumferentially extending parallel limbs of which are such that said knob is engageable with and removable from said shoot through one of the circumferentially extending limbs of said H-shaped slot but not through the other, said other limb being the limb occupied by the knob when the shoot is in a locking position.

Conveniently the bolt is a barrel bolt wherein the shoot is rotatable in the case.

One example of the present invention is illustrated in the accompanying drawings, wherein: Figure 1 is a side elevational view of a barrel bolt; and Figures 2 and 3 are sectional views on the lines 2-2 and 5-3 respectively of Figure 1.

Referring to the drawings it can be seen that the bolt consists of four components, a case 11, a shoot 12, an operating knob 13 and a keep 14. The knob 13, the elongate case 11 and the keep 14 are moulded in synthetic resin material, conveniently Nylon 6, although it is believed that other synthetic resin materials with or without reinforcing fillers, such as glass fibres, may be suitable. The keep 14 conveniently has the same cross-section as the case 11 although naturally it is of considerably shorter axial length. The knob, the case and the keep may be moulded in the same operation in the same mould tools and this may prove to be the most convenient and economic procedure. It would however be possible to produce a single moulding in which the keep and the case are integral with one another, and then to separate the case from the keep by a simple cutting operation.

The case 11 has an axially extending through passage of substantially circular crosssection within which is slidably and rotatably received the cylindrical steel shoot 12. The inner diameter of the passage 15 slightly exceeds the outer diameter of the shoot 12, and the wall of the passage 15 includes protrusions, conveniently six axially extending equiangularly spaced integral ribs 16 of semi-circular cross-section. The ribs 16 protrude radially inwardly into the passage 15 and engage the shoot 12. The engagement of the shoot 12 with the ribs 16 provides the bolt with a smooth and positive operating "feel" by providing a frictional drag on the bolt.In addition of course the provision of the ribs 16 overcomes any tolerance problems there may be in matching the diameter of the shoot 12 to the passage 15, and thus a relatively wide range of tolerance can be accepted without the shoot 12 either binding within the case, or being free to rattle within the case. It will be understood that the provision of the ribs 1 6 obviates the need for a cross-drilling in the shoot receiving a spring and ball arrangement.

The passage of the keep 14 may have similar ribs if desired, and more or less than six ribs may be chosen. Conveniently from three to seven ribs are used. It will be recognised that the same benefits can be achieved in other ways. For example the passage 15 could be of polygonal rather than circular cross-section or could be basically of circular cross-section with one or more axially extending flat surfaces. Alternatively the passage could be of generally circular cross-section with one or more helically extending ribs thereon. As a further alternative the passage could be of circular cross-section with a shoot of polygonal or other non-circular cross-section.

Adjacent one end, the wall of the case 11 is formed, during the moulding operation, with a generally H-shaped slot 17 comprising first and second axially spaced laterally extending limbs 18, 19 joined by an axially extending region 21. The slot 17 is in the upper region of the case 11, the lower face of the case 11 being flat, so as to seat on the component to which the case is to be secured. The operating knob 15 extends through the slot 17 and into engagement with the shoot 12. The shoot 12 is formed adjacent one axial end thereof with a circumferentially extending groove 22 which defines in the shoot 12 a cylindrical neck 23 of reduced diameter. The neck 25 is concentric with the remainder of the shoot 12 and the knob 13 includes a bifurcated collar-like region 24 received within the groove 22 and otatably engaging the neck 23.As can be seen in Figure 3, the arcuate limbs of the region 24 define between them a part-cylindrical passage within which the neck 25 is received, the portion 24 being engageable around the neck 23 as a snap-fit.

When fitted to the neck 23 the outer surface of the portion 24 is flush with the remainder of the outer surface of the shoot.

It will be recognised that while the shoot 21 can rotate relative to the knob 13, the shoot 12 cannot be moved axially relative to the knob 13 since the portion 24 of the knob 13 is received within the groove 22. Thus the knob 13 can be moved to a position aligned with the portion 21 of the slot 17 and by passing the knob 13 along the portion 21 the shoot 12 can be slid axially relative to the case 11 between a withdrawn position wherein the knob 13 occupies the portion 19 of the slot 17 and an operative position wherein the knob 13 occupies the portion 18 of the slot 17 and the end of the shoot 12 remote from the knob 13 projects beyond the end of the case 11.

As can be seen in Figures 1 and 2 both the case 11 and the keep 14 are provided with fixing holes 25 for the reception of mounting screws.

The bolt is assembled in the following manner. The shoot 12 already formed with the groove 22 is inserted into the case so that while the majority of the shoot 12 is housed within the case, the neck 23 of the shoot is exposed in the portion 19 of the slot 17. The knob 13 is then offered to the shoot in a direction radially of the shoot so that the collar-like portion 24 enters the groove 22 and is snapped into engagement with the neck 23.

As the snap action between the portion 24 of the knob 15 and the neck 23 occurs, the two limbs of the portion 24 are flexed outwardly to pass over the maximum diameter of the neck 23. It can be seen from Figure 1 that the portion 19 of the slot 1 7 is extended at its opposite ends by comparison with the portion 18, and this extension by comparison with the portion 18 permits the necessary outward flexure of the limbs of the portion 24 during assembly. It will be recognised therefore that when the knob 13 lies within the portion 18 it is not possible to disengage the knob 13 from the shoot since the ends of the portion 1 8 will obstruct the necessary outward flexure of the limbs of the portion 24.In a modification the portion 24 is a complete annulus and the shoot is snap engaged therewith by driving the shoot through the aperture of the portion 24 until the portion 24 aligns with and snaps into the groove of the shoot.

It will be understood that in the operative position of the shoot, the knob 13 will be moved so that it occupies one or other of the end regions of the portion 18 of the slot 1 7 and is not aligned with the portion 21 of the slot. As with the conventional bolt the knob 13 will thus prevent the shoot 12 being slid axially back to its withdrawn position. However, with a conventional bolt, it is possible for an intruder to manipulate the region of the shoot which extends between the case and the keep to rotate the shoot and thus the knob of the conventional shoot to a position in which the knob is aligned with the axial portion of the slot and then to work the bolt axially back to its withdrawn position so opening or releasing the bolt.Such an operation is far more difficult to perform with the bolt construction described above, since the bolt can rotate relative to the knob 13. If desired the knob and/or the region 18 of the slot 1 7 can be shaped to provide a resistance to movement of the knob 13 in the circumferential direction. Such resistance will be easily overcome when manipulating the knob 13 directly, but will be difficult if not impossible to overcome when attempting, in an unauthorised manner, to move the knob by manipulation of the shoot. Moreover, if an attempt is made to saw through the shoot between the case and the keep 14 then the shoot will be free to rotate in the case 11 without affecting the position of the knob 13, and such rotation will of course greatly hinder any sawing action.

The comments made above in relation to rotation of the shoot relative to the knob 13 apply to barrel bolt constructions, but generally will not apply to slide bolt constructions.

However, the use of a moulded synthetic resin case is of course applicable to slide bolt constructions as is the snap engagement of the knob on the shoot. It will be understood that a desired barrel bolt construction will embody both a moulded synthetic resin case and the facility for relative rotation between the shoot and the knob. However, these two features can be used independently of one another if desired.

The use of a moulded synthetic resin case facilitates the incorporation in the bolt construction of a locking device to prevent axial movement of the shoot or slide, since the case wall thickness is such as to be able to accommodate a transverse screw threaded bore, communicating with the axial pasage of the case, within which a grub screw or the like can be mounted. The grub screw can be rotated using an Allen key or the like to screw it inwardly to engage the shoot. If desired the shoot can have a recess into which the grub screw can protrude so that movement of the shoot is resisted by abutment with the grub screw rather than simply by friction. Normally of course it will be desirable to lock the shoot in its operative position.The conventional extruded aluminium case has a wall thickness which is too small satisfactorily to accommodate such a locking device, and whereas the moulded case could if necessary, be moulded with a thickened boss at a chosen point to accommodate the device, such a facility is not available when manufacturing the conventional case by extrusion.

The facility for movement of the knob about the axis of the shoot is useful where the bolt is a slide bolt or a "necked" bolt, that is to say it has a shoot cranked at its operative end. Slide bolts have a non-circular section shoot engaged in a correspondingly shaped passage of their respective case. Such bolts are often used with the shoot vertical and the cranking or cross-section of the shoot prevents rotation of the shoot relative to the case of bolt notably in in the operative position of the shoot in the case of the "necked" bolt. Thus in the conventional "necked" bolt or slide bolt the lever will be in, or aligned with, the axial region of the slot in the case, and the shoot may inadvertently move, under the combined action of vibration and gravity, to its retracted position. Where the knob can be rotated on the shoot then the knob can be moved into the upper of the two limbs of the H-shaped slot in the case and so will prevent such inadvertent movement of the shoot to the retracted position.

Claims

1. A bolt comprising a case having therein an axial passage slidably receiving a shoot, said case being moulded in a synthetic resin material.

2. A bolt as claimed in claim 1 wherein the cross-sectional shapes of the shoot and said passage are such that there are circumferentially spaced regions of contact between the shoot and the wall of the passage.

3. A bolt as claimed in claim 1 or claim 2 wherein the wall of the passage of the case which slidably receives the shoot is formed with one or more integral ribs or protrusions engaging the shoot.

4. A bolt as claimed in claim 3 wherein the wall of said passage is formed with from 3 to 7 equi-angularly spaced axially extending integral ribs which engage the surface of the shoot.

5. A bolt as claimed in claim 3 or claim 4 wherein the ribs are of part-circular cross-section.

6. A bolt as claimed in any one of claims 1 to 5 wherein the case is of a decorative colour.

7. A bolt as claimed in any one of claims 1 to 6 wherein the colour of the synthetic resin material used to form the case, and the colour of the shoot are different so as to provide a tonal contrast between the shoot and the case.

8. A bolt as claimed in any one of claims 1 to 7 further including an operating knob which extends radially outwardly from the shoot, and which is engaged with the shoot in a manner resisting relative axial movement between the knob and the shoot, while permitting relative rotational movement of the knob and the shoot.

9. A bolt as claimed in claim 8 wherein the shoot is formed with a circumferentially extending groove defining a neck of reduced diameter and the knob includes a collar-like portion received in said groove and rotatably engaging said neck.

10. A bolt as claimed in claim 9 wherein the outer surface of said collar-like portion is flush with the surface of the shoot.

11. A bolt as claimed in claim 8, claim 9 or claim 10 wherein said knob is moulded in a resilient synthetic resin material and is engaged as a snap-fit on said shoot.

12. A bolt as claimed in claim 11 where dependent upon claim 8 or claim 9 and wherein said collar-like portion is split to facilitate snap engagement in said groove.

13. A bolt as claimed in claim 12 wherein said knob extends from said shoot through a generally H-shaped slot in the wall of said case, the circumferentially extending parallel limbs of which are such that said knob is engageable with and removable from said shoot through one of the circumferentially extending limbs of said H-shaped slot but not through the other, said other limb being the limb occupied by the knob when the shoot is in a locking position.

14. A bolt as claimed in anyone of claims 1 to 13 wherein the case carries a transversely movable locking device movable to engage, and resist axial movement ofthe shoot.

15. A bolt as claimed in claim 14 wherein said device is a grub screw.

16. A bolt substantially as hereinbefore described with reference to the accompanying drawings.

17. A bolt including an elongate shoot received in a case for axial movement relative thereto, and, an operating knob which extends radially outwardly from the shoot, and which is engaged with the shoot in a manner resisting relative axial movement between the knob and the shoot, while permitting relative rotational movement of the knob and the shoot.

1 8. A bolt as claimed in claim 1 7 wherein the shoot is formed with a circumferentially extending groove defining therein a neck of reduced diameter, and the knob includes a collar-like portion received in said groove and rotatably engaging said neck.

19. A bolt as claimed in claim 18 wherein the outer surface of said collar-like portion is flush with the surface of the shoot.

20. A bolt as claimed in claim 18 or claim 1 9 wherein said knob is moulded in a resilient synthetic resin material and said collar-like portion is engaged as a snap-fit on said shoot.

21. A bolt as claimed in claim 20 where dependent upon claim 18 or claim 19 wherein said collar-like portion is split to facilitate snap engagement of said portion of said groove of said shoot.

22. A bolt as claimed in claim 21 wherein said knob extends from said shoot through a generally H-shaped slot in the wall of said case, the circumferentially extending parallel limbs of which are such that said knob is engageable with and removable from said shoot through one of the circumferentially extending limbs of said H-shaped slot but not through the other, said other limb being the limb occupied by the knob when the shoot is in a locking position.

23. A bolt as claimed in anyone of claims 17 to 22 wherein said shoot is rotatable in said case.