A RETENTION DEVICE FOR ELONGATE OBJECTS

Abstract: The invention concerns a fixing device to fix an elongate object, against movements in its longitudinal direction, said device comprising: an elongate housing (2) having a first end portion (10) and a second end portion (20), an internal elongate channel (25) to receive the elongate object (30), which channel (25) is defined by a wall (5) of the housing (2), extends between the first end portion (10) and the second end portion (20) and has a mouth at the first end portion (10), and at least one clamping element (35). The device is characterized in that the at least one clamping element (35) is adapted to extend forwardly from an associated opening in the wall (5) and into the interior of the channel (25) in engagement with the elongate object (30), and that the at least one clamping element (35) can affect a portion of the surface of the elongate object (30) received in the channel (25) by a minimum clamping force and an increasing clamping force depending on a respective movement of the object (30) in the longitudinal direction of it, thereby clamping the elongate object by a variable clamping force between the wall (5) of the housing (2) and the at least one clamping element (35).

Description: A retention device for elongate objects The present invention concerns a fixing device to clamp an elongate object against movements in its longitudinal direction, said device comprising: an elongate housing having a first end portion and a second end portion, an internal elongate channel to receive the elongate object, which channel is defined by a wall of the housing, ex- tends between the first end portion and the second end portion and has a mouth at the first end portion, and at least one clamping element. Fixing devices of this type are known e.g. from US Patent No. 2 657 671, US Patent No. 3 871 780 and GB Patent No. 2 078 508. Particularly the two last-mentioned fixing de¬ vices use ring-shaped clamping elements which clamp a protruding elongate object carefully centered inside a channel, a cylindrical housing or a pipe, which may form part of either a table leg or a walking stick, against movements in the longitudinal direction of the object, said clamping element clamping around the entire periph¬ ery of the object and being capable of sliding or rolling by itself along an internal conical face in the cylindri- cal housing. It is common to these known devices that they fix the object with a minimum clamping force when it is attempted to move the object in an outward direction, and with a clamping force which increases the further the object is moved into the surrounding housing. The object can hereby readily be pulled out of the housing by over¬ coming said minimum clamping force, while an inwardly di¬ rected movement is prevented. When the elongate object is affected by a lateral force at the end protruding from the housing, it is a serious drawback of these known fixing device that the object will tend to tilt to and fro corresponding to the diame¬ ter difference between the object and the surrounding pipe. This problem increases with an increasing diameter difference and is thus of importance particularly when the object is manufactured with a diameter tolerance, or when objects of different diameters within small ranges are to be used. The object of the invention is to remedy the drawback de- scribed above. This is achieved according to the inven¬ tion by means of a fixing device of the type which is de¬ fined in the opening paragraph and is characterized in that the at least one clamping element is adapted to ex¬ tend forwardly from an associated opening in the wall and into the interior of the channel in engagement with the elongate object, and that the at least one clamping ele¬ ment can affect a portion of the surface of the elongate object received in the channel by a minimum clamping force and an increasing clamping force depending on a re- spective movement of the object in the longitudinal di¬ rection of it, thereby clamping the elongate object by a variable clamping force between the wall of the housing and the at least one clamping element. When the object is held clamped between the clamping ele¬ ment and the wall of the housing, the above-mentioned tendency of the object to tilt is avoided, as the object is supported by the channel at the first end portion as well as at the clamping element. The fixing device of the invention may be used to par¬ ticular advantage as a writing utensil to fix a piece of writing chalk e.g. at schools. Particularly writing chalk is produced in practice with certain tolerances, which makes the invention particularly expedient for this type of objects. The invention may also be used to advantage for other objects which are affected by lateral forces in a position in which they have been moved partly out of the surrounding housing. What is contemplated here is e.g. lamp rods where the housing may form part of a wall mount. Further, the device may be used for fixing e.g. parasols, floor lamps with variable height adjustment, music stands, microphone stands or easels, or more gener¬ ally in connection with all forms of telescopingrod- shaped elements and e.g. in connection with the feeding of rod-shaped r objects to be cut in automatic workshop ma¬ chines . Advantageous embodiments are defined in the subclaims. Thus, when the fixing device is constructed as stated in claim 2, the user of the fixing device can release the clamping element, which is ring-shaped, from the outside of the housing in a particularly simple and easy manner and can thereby move the elongate object freely in both directions. In all the known devices described above it is necessary to move the elongate object completely or partly out of the surrounding housing or pipe to subse¬ quently place the object in a position in which the ob¬ ject protrudes less from the said end portion. The actual clamping is intensified in this embodiment in that the ring-shaped clamping element moves or rolls to¬ ward the channel in the inclined slot, when the object is moved in a first direction in accordance with the orien- tation of the slot so that the object is clamped by wedge-effect. When the clamping element is to be released for free movement, the ring part extending along the ex¬ terior of the housing is merely gripped by the hands, and the ring may then readily be moved upwards along the in- clined slot away from the mouth in the channel, thereby releasing the clamping completely or partly. If it is at- tempted to move the object in a direction opposite to the said first direction without release of the clamping ele¬ ment, the clamping element will affect the object by a minimum clamping force, ensuring that the object cannot drop out by itself. Expediently, at least one annular de¬ pression may be provided along at least a portion of the exterior of the housing, as the at least one ring-shaped clamping element may extend in an associated annular de¬ pression along the exterior of the housing and serves to guide the ring. In this connection, the at least one ring-shaped clamping element may be adapted to protrude from the associated annular depression, which makes it easier to grip the ring by the hands. It is moreover contemplated that the said slot may advan¬ tageously extend obliquely from the exterior of the hous¬ ing a direction from the first end portion, and two of the said inclined slots with associated ring-shaped clamping elements may be provided in a special embodi- ment, where a first slot extends obliquely from the exte¬ rior of the housing in a direction from the first end portion, and a second slot extends obliquely from the ex¬ terior of the housing in a direction toward the first end portion. Unintentional movement of the object in both di- rections can hereby be prevented. According to a further preferred embodiment, at least one clamping element may be arranged in the vicinity of the first end portion, via which the object must be capable of being pulled out or inserted, thereby providing a par¬ ticularly safe fixing of the object in the vicinity of the end where the object may be subjected to lateral forces. Furthermore, the housing and/or the channel may have a circular or polygonal cross-section, according to the cross-sectional shape of the object. According to a further embodiment, the channel may also be formed with a mouth at the second end portion, and this mouth may be used for inserting the object into the housing, without the clamping element having to be re- moved or released completely. In this case, the object, when being inserted, will press the clamping element along the slot in a direction toward the exterior of the housing, whereby the elastic clamping element will yield to allow the object to pass. In addition, the channel wall opposite the at least one clamping element may be formed with at least two longitudinal support lines, which ensures an even more reliable support of the ob¬ ject, particularly if the object has an uneven surface. The invention will be explained more fully below with reference to the accompanying drawing, in which fig. 1 is a longitudinal central sectional view through an embodiment of the device of the invention, fig. 2 is a view similar to fig. 1, but with the elongate object removed, fig. 3 is an end view of the device in an alternative em- bodiment of the channel without an inserted object and with two longitudinal support lines, and fig. 4 is a perspective view of the device. As appears from fig. 1 in particular, a fixing device 1 of the invention comprises an elongate housing 2, which is shown to have a circular cross-section, but which may also have a polygonal cross-section. The housing 2 has a wall 5 defining an internal channel 25 which has a mouth at a first end portion 10 of the housing 2 and a mouth at a second end portion 20. The channel 25 has an essen- tially constant cross-section - at least between the clamping element and the first end portion 10, but pref¬ erably in the entire longitudinal direction. In addition, an inclined slot 40, which terminates at the exterior of the housing and in the channel 25, respectively, is formed in the wall 5 in the vicinity of the first end portion 10. As shown, the slot 40 extends obliquely from the exterior of the housing 2 in a direction from the first end portion 10 and toward the second end portion 20. The inclined slot 40 extends in the wall 5 along the circumference of the housing 2. The extent of the slot 40 is of such a size as to provide clamping of an elongate object 30, which is shown to have a circular cross-sec¬ tion, such as a lamp rod or a piece of writing chalk, in- serted into the channel with an end protruding from the housing 2 at the first end portion 10, as will be ex¬ plained more fully below. The fixing device 1 moreover comprises a clamping element in the form of an elastically resilient 0-ring 35 of e.g. rubber, which has been moved down over the housing 2 and is partly embedded in the slot 40 to engage the sides of the slot and the elongate object 30. As will appear, the ring 35 moreover extends along a portion of the exterior of the housing 2. Clearly, the fixing device 1 must be constructed such that the clamping element or the ring 35 enters the channel 25 at the slot 40 when the object has been removed from the housing 2. When the object 30 is inserted into the channel via the second end portion 20 past the ring 35, the ring expands to engage the object, thereby providing a minimum clamping force. As appears from the drawing, the clamping force urges the object 30 into engagement with the part of the channel 25 which is opposite the slot 40. Since, as mentioned, the channel has a constant cross-section in the longitudinal direction, the object 30 will thus engage the wall 5 in the channel 25. As the object 30 engages the channel 25 at the first end portion 10 as well as at the clamping element 35, the object 30 is effectively prevented from tilting to and fro in the channel 25 when the object is affected by lateral forces, i.e. forces having a compo¬ nent perpendicular to the longitudinal direction of the device 1, on the protruding part. It is characteristic of the device 1 of the invention that the object 30, which may particularly advantageously be a piece of writing chalk, is fixed against movements in the longitudinal direction by a minimum clamping force which, because of the shown orientation of the inclined slot 40 extending from the exterior of the housing 2 in a direction from the first end portion 10, prevent the ob¬ ject 30 from being readily moved out of the channel 25 at the first end portion 10. Because of the inclined slot 40, the ring-shaped clamping element 35, which engages the object 30 and a portion of the wall 5 of the housing 2 in the slot 40, will move along the inclined slot 40 toward the second end portion 20, when it is attempted to move the object 30 toward this end portion 20 by a corre¬ spondingly directed force on the protruding end face of the object 30, e.g. when the object is a piece of writing chalk which is used on a blackboard. This movement, which results from the movement of the clamping element 35 by the object 30, presses the clamping element 35 further down into the slot 40 and thus acts as wedge which af- fects the object 30 by an increasing clamping force, thereby effectively preventing further insertion of the object. In fig. 2, the device 1 is shown without an inserted ob- ject 1, and it appears clearly how the 0-ring along a portion of its extent extends inside the channel when the ring engages the bottom of the slot 40. As shown in fig. 3, the interior of the housing 1, oppo- site the at least one clamping element, may comprise at least two longitudinal support lines 50 formed by provid¬ ing a longitudinal recess in the wall 5. These support lines 50 particularly serve to ensure that the object - if it has an uneven surface - is still kept supported by the channel at the first end portion as well as at the clamping element. Fig. 4 shows the device 1 in perspective view and pro¬ vided with an additional, but oppositely directed slot 40' with an associated 0-ring 35'. This modified device is particularly useful in situations where the object 35 is to be fixed securely, but easily releasably, against movements in one and the other direction. Of course, it is within the scope of the invention to select the orien- tation of the inclined slot as desired, and the slot 40 shown in figs. 1-3 may thus also be oppositely oriented. It is contemplated according to the invention that the housing 1 may be made directly from a natural material, e.g. from a bamboo (see fig. 4), which is merely to be treated with simple means. This results in an environmen¬ tally unharmful structure. Finally, an annular depression (not shown in the drawing) may be provided along a por¬ tion of the exterior of the housing at the slot 40. This depression forms a groove to guide the 0-ring so that the 0-ring cannot move unintentionally along the exterior of the housing 1.

Claims: P a t e n t C l a i m s 1. A fixing device to clamp an elongate object against movements in its longitudinal direction, said device com¬ prising: - an elongate housing (2) having - a first end portion (10) and a second end portion (20), — an internal elongate channel (25) to receive the elon¬ gate object (30) , which channel (25) is defined by a wall (5) of the housing (2) , extends between the first end portion (10) and the second end portion (20), and has a mouth at the first end portion (10), and - at least one clamping element (35), c h a r a c t e r i z e d in - that the at least one clamping element (35) is adapted to extend forwardly from an associated opening in the wall (5) and into the interior of the channel (25) in en¬ gagement with the elongate object (30), and - that the least one clamping element (35) can affect a portion of the surface of the elongate object (30) re- ceived in the channel (25) by a minimum clamping force and an increasing clamping force depending on a. respec¬ tive movement of the object (30) in the longitudinal di¬ rection of it, - thereby clamping the elongate object (30) by a vari- able clamping force between the wall (5) of the housing (2) and the at least one clamping element (35). 2. A fixing device according to claim 1, c h a r a c t e r i z e d in - that the housing comprises at least one slot (40) which - terminates at the exterior of the housing (2) and at the said opening in the wall (5), and - extends obliquely from the exterior of the housing (2) in a direction from or toward the first end portion (10), - that the at least one clamping element (35) is ring- shaped and elastic, - extends partly in an associated slot (40) and partly along the exterior of the housing (2), and - that the at least one clamping element (35) can affect the elongate r object (30) by the minimum clamping force and the increasing clamping force by movement along the associated inclined slot (40). 3. A fixing device according to claim 2, c h a r a c t e r i z e d in - that at least one annular depression is provided along at least a portion of the exterior of the housing (2), and - that the at least one ring-shaped clamping element (35) extends in an associated annular depression along the ex¬ terior of the housing and optionally protrudes from the associated annular depression. 4. A fixing device according to claim 2 or 3, c h a r a c t e r i z e d in - that the slot (40) extends obliquely from the exterior of the housing (2) in a direction from the first end por¬ tion (10) . 5. A fixing device according to any one of the preceding claims 2-4, c h a r a c t e r i z e d in - that two of the said inclined slots (40, 40') with as¬ sociated ring-shaped clamping elements are provided, where a first slot (40) extends obliquely from the exte- rior of the housing (2) in a direction from the first end portion (10), and a second slot (40') extends obliquely from the exterior of the housing (2) in a direction to¬ ward the first end portion (10). 6. A fixing device according to any one of the preceding claims, c h a r a c t e r i z e d in - that the channel (25) has a circular cross-section or a polygonal cross-section. 7. A fixing device according to any one of the preceding claims, c h a r a c t e r i z e d in - that the elongate housing (2) is made from a natural material, such as from a bamboo. 8. A fixing device according to any one of the preceding claims, c h a r a c t e r i z e d in - that at least one clamping element (35) is arranged in the vicinity of the first end portion (10). 9. A fixing device according to any one of the preceding claims, c h a r a c t e r i z e d in - that the channel (25) also has a mouth at the second end portion (20). 10. A fixing device according to any one of the preced- ing clams, c h a r a c t e r i z e d in - that at least two longitudinal support lines (50) are provided in the channel wall (5) opposite the at least one clamping element (40).

Inventors: VALENTINUS NIELS-FINN, VALENTINUS, NIELS-FINN
Applicants: VALENTINUS NIELS FINN, VALENTINUS, NIELS-FINN
Application year: 1996
Main classification: F16B2
IPC codes: B43K23, F16B7