| JP2001063560 | DRIVING DEVICE FOR CARRYING TRUCK |
| WO/2004/062959 | RAIL ARRANGEMENT, CAR, AND TRANSPORT SYSTEM FOR CONTACTLESS POWER TRANSMISSION |
| JP3842369 | SUSPENSION CONVEYER |
Henning, Persson
Anders
Henning, Persson
Anders
| 1. | A device in a curve section of an overhead con veyor, said curve section (1) forming a transition between a first rotatable shaft (2) and a second rotat¬ able shaft (3) and being, at each end portion, nonrotat ably connected to an adjoining end of respectively the first and the second shaft and, hence, rotatable with said shafts, and load carriers (L) being suspendible from the shafts and the curve section as well as propellable by the rotation of the shafts (2, 3) and the curve sec¬ tion (1), c h a r a c t e r i s e d in that the curve section (1) comprises at least two curve segments (6) which have essentially the same profile and the same outer diameter as the shafts ( 2, 3 ) and are rotatably supported along the curve section ( 1 ) and which have cooperating engagement means (13, 14) for transferring torque between the curve segments ( 6) and, hence, between the end portions of the curve section ( 1) . |
| 2. | A device as claimed in claim 1, wherein the curve segments (6) are supported along, and are rotatably mount¬ ed on, a stationary supporting rod (7) extending between the end portions of the curve section. |
| 3. | A device as claimed in claim 2, wherein the end portions of the curve section are rotatably mounted on the supporting rod (7) . |
| 4. | A device as claimed in claim 2 or 3, wherein each curve segment ( 6) is cylindrical and coaxially supported by the supporting rod ( 7) . |
| 5. | A device as claimed in any one of the preceding claims, wherein there is a certain play between the en¬ gagement means (13, 14) of adjoining curve segments (6). |
| 6. | A device as claimed in any one of the preceding claims, wherein the mutually engaging curve segments (6) have such an outer shape that the circumferential surface of the curve section (1) is essentially even and conti¬ nuous. |
| 7. | A device as claimed in any one of the preceding claims, wherein the curve segments (6) are of equal size and have the same shape. |
| 8. | A device as claimed in any one of the preceding claims, wherein the engagement means (13, 14) comprise clawcoupling elements for claw coupling between adjoin¬ ing curve segments ( 6) or between curve segments (6) and the end portions of the curve section (1), the curve seg¬ ments ( 6) being provided with clawcoupling elements at both ends. |
| 9. | A device as claimed in any one of the preceding claims, wherein the engagement means comprise spaced apart teeth (13) which project in parallel with the cen¬ tre axis (C) of the curve segment (6) and extend radially in relation to said centre axis, grooves (14) being defined between the teeth ( 13) and adapted to accommodate the teeth (13) of an adjoining curve segment (6). |
| 10. | A device as claimed in claim 9, wherein the teeth (13) are of decreasing thickness in the direction axially away from the curve segment (6), the grooves (14) between the teeth ( 13 ) having a shape corresponding to that of the teeth so as to form a play between adjoining curve segments (6). |
| 11. | A device as claimed in claim 9 or 10, wherein the teeth (13) are arranged at equal angular pitch. |
| 12. | A device as claimed in claim 11, wherein the teeth (13) at the one end of each curve segment (6) are circumferentially offset in relation to the teeth ( 13) at the other end of the curve segment (6) . |
| 13. | A device as claimed in claims 912, wherein the teeth ( 13) are of increasing thickness in the radial direction out and away from said centre axis (C). |
| 14. | A device as claimed in any one of claims 213, wherein the curve section ( 1 ) at each end portion has an end piece (9, 10), whose one end is nonrotatably and coaxially connected to the associated shaft (2, 3) and whose other end is rotatably and coaxially mounted on the supporting rod (7) and comprises engagement means for engaging the engagement means of the adjoining curve seg ment (6) . |
| 15. | A device as claimed in any one of the preceding claims, wherein the curve section (1) is supported by roller bearings (8) which are in rolling contact with the outer surface of the curve section ( 1 ) . |
| 16. | A device as claimed in any one of the preceding claims, wherein the shafts (2, 3) and the curve section (1) have a substantially circular crosssection, the load carriers (L) having inclined rollers (T) for frictional engagement and rolling contact with the outer surface of the shafts and the curve section, thereby to propel the load carriers (L) when the shafts and the curve section are rotated. |
| 17. | A device as claimed in any one of claims 115, wherein the shafts and the curve section have an outer spiral groove engaged by suspension means associated with the load carriers, thereby to propel the load carriers when the shafts and the curve section are rotated. |
| 18. | A device in a curve section in an overhead conveyor, said curve section (1) forming a transition between a first rotatable shaft ( 2 ) and a second rotat¬ able shaft (3) and being, at each end portion, nonrotat ably connected to an adjoining end of respectively the first and the second shaft and, hence, rotatable with said shafts (2, 3), load carriers (L) with inclined rollers (T) for frictional engagement and rolling contact with the outer surface of the shafts and the curve sec¬ tion being propellable by the rotation of the shafts and the curve section, said curve section (1) comprising: two end pieces (9, 10) which at one end are each nonrotat ably and coaxially connected to the respective shafts (2, 3 ) , a stationary supporting rod ( 7) which extends along the curve section (1) and on which the end pieces (9, 10) are rotatably mounted, and at least two cylindrical curve segments (6) which are rotatably and coaxially mounted on the supporting rod (7) and are disposed between the end pieces (9, 10), each curve segment (6) having at each end clawcoupling elements ( 13) with equivalents at said other end of the respective end pieces (9, 10), the claw coupling elements (13) being, with a certain play, in engagement with adjoining clawcoupling elements (13), thereby to transfer torque between the end portions of the curve section (1) , and the curve section ( 1) and the shafts (2, 3) having a circular crosssection of essen¬ tially the same outer diameter. |
| 19. | An overhead conveyor, c h a r a c t e r i s e d in that it is provided with one or more devices as claim ed in any one of the preceding claims. |
| 20. | The use of separate curve segments with cooper¬ ating engagement means for constructing a device in a curve section as claimed in any one of claims 118. |
Field of the Invention
This invention generally relates to overhead con¬ veyors and especially concerns the curves of such con¬ veyor systems. To be more specific, the invention bears upon a device of the type defined in the preamble to appended claim 1.
Background of the Invention
In overhead conveyors, it is known to propel load carriers that are suspended from or in frictional and rolling contact with rotatable shafts. This basic tech¬ nique is described in e.g. Patent Specification US-A- 3,850,280, which is hereby incorporated by reference.
In such conveyor systems, it is usually a desidera¬ tum that transport be possible in different directions, and various solutions have therefore been presented as regards the provision of curves for overhead conveyors. PCT Publication WO 88/04641 teaches such a known solu¬ tion, according to which a so-called driven curve forms a transition between two rotatable, straight shafts. In a preferred embodiment, the curve itself is made up of a flexible tube consisting of polyurethane rubber or some similar material. However, this tried solution has proved to possess certain drawbacks, in particular when used under special conditions, such as varying temperature conditions. The following inconveniences have, inter alia, been observed.
- The rubber tube forming the curve acts as a tor- sional spring during the propulsion by rotation, result¬ ing in energy losses. - Being made of a flexible material, the curve has to be supported at a fairly large number of mounting points, resulting in an increase in costs.
- At high ambient temperatures, for instance exceed¬ ing 50°C, the rubber tube may burst as a result of fati¬ gue due to internal friction.
- At low temperatures ( for instance about 5 c C) , on the other hand, the rubber tube becomes so rigid that there is a considerable increase in load on the motors rotating the shafts connected to the rubber tube.
- For a 90° curve with a rubber tube of the above type, it has proved extremely difficult or even impos- sible to obtain a curve radius below 300 mm. Objects of the Invention
In view of the above, one object of the invention is to obviate these inconveniences by providing a device in a curve section which has little temperature sensitivity and thus is able to operate in reliable fashion without any risk of functional disorders in the form of material fatigue and so forth.
A special object of the invention is that it should be possible to operate the device in its entirety with lower energy losses than has hitherto been possible according to the prior art.
Another object of the invention is to provide a device in a curve section enabling as small curve radii as 150-200 mm. A further object of the invention is that the device should comprise but a few component parts and be of sim¬ ple design, the reliability of the device being however in no way compromised.
Summary of the Invention According to the invention, these and other objects, which will appear from the following description, have now been achieved by the provision of a device which is of the type described by way of introduction and which further has the distinctive features recited in the char- acterising clause of appended claim 1. Preferred embodi¬ ments of the device according to the invention are stated in appended subclaims 2-17.
These objects are in particular attained by a device as claimed in appended claim 18, as well aε: an overhead conveyor as claimed in appended claim 19. More¬ over, these objects are achieved by the use claimed in appended claim 20.
The fact that the curve section of the inventive device comprises a number of curve segments results in high flexibility. The curve segments and their engagement means can easily be standardised and modularised in such a manner that the number of curve segments is propor¬ tional to the aimed-at curve angle. Furthermore, the cooperating engagement means of the curve segments may easily be so designed as to minimise the energy losses when torque is transferred through the curve. Brief Description of the Drawings
The invention and its many advantages will be de¬ scribed in more detail below with reference to the accom¬ panying, schematic drawings showing a currently preferred embodiment of the device according to the invention. In the drawings,
Fig. 1 is a perspective view obliquely from above of a device in a curve section according to the invention;
Fig. 2 is a sectional view of a coupling (to the right in Fig. 1) associated with the curve section; Fig. 3 is a partly sectional view of an end piece associated with the coupling shown in Fig. 2;
Fig. 4 is an end view on a larger scale of a curve segment belonging to the curve section shown in Fig. 1; Fig. 5 is a side view of the curve segment; and Fig. 6 is a perspective view on an even larger scale of the curve segment shown in Figs 4 and 5. Description of the Preferred Embodiment Fig. 1 shows a device in a curve section which is generally designated 1 and in the following also will be referred to as a curve and which is in agreement with the preferred embodiment of the invention. The curve 1 forms a transition between two straight shafts 2, 3, which in
known manner are rotatable. The shafts 2, 3, which pre¬ ferably have a perfectly circular cross-section, for instance a tubular shape, are in known manner arranged in sectional supporting elements 4, 5, When e.g. the shaft 2 is rotated (the arrow A), the curve 1 should transfer torque to the other shaft 3. The shaft 2 is driven by a motor M (schematically illustrat¬ ed). In the illustrated embodiment, the curve 1 forms a 90° transition between the shafts 2, 3. Thus, the shafts 2, 3 and the curve 1 rotate at the same speed.
A load carrier L (schematically illustrated) , for example an overhead carriage suspended from the driven shaft 2 and having inclined rollers T in rolling contact with the shaft 2, is thus propelled from the shaft 2, through the curve 1 and onto the shaft 3. Load carriers of this type are disclosed in US-A-3, 850,280 (Fig. 2) and WO 88/04641 (Fig. 2). In order that the transition between the shafts 2, 3 should be as smooth as possible, the shafts 2, 3 and the curve 1 have essentially the same profile and the same outer diameter.
The curve 1 itself is composed of a number of curve segments, which are generally designated 6 and which are in permanent engagement with each other. A couple of curve segments 6 have been omitted in Fig. 1 in order to show a stationary supporting rod 7 which has a circular cross-section and on which the curve segments 6 are so mounted as to be freely rotatable. External support is furthermore provided in the form of an external roller bearing 8 of a type known per se. At each end, the curve 1 has an end piece 9, 10, whose one end is non-rotatably and coaxially connected to the end of the adjoining shaft 2 or 3 and whose other end is rotatably and coaxially mounted on the supporting rod 7. A coupling element 11 and 12 is inserted and anchored in the respective end pieces 9, 10. To enable the trans¬ fer of torque, each curve segment 6 has, at each of its ends, means for cooperating engagement with adjoining
curve segments 6 or adjoining engagement means on the coupling elements 11, 12. In Fig. 1, these engagement means are in the form of mutually engaging claw-coupling elements having teeth 13 for engaging corresponding grooves 14 in adjoining curve segments 6.
To ensure reliable propulsion of the load carriers L through the curve 1, the mutually engaging curve segments 6 are given such an outer shape that the circumferential surface of the curve 1 is essentially even and conti- nuous. The engagement between the curve segments 6 must be such that there is no risk of the rollers T of the load carrier L getting stuck in the joint between two adjoining curve segments 6.
Fig. 2 shows how the shaft 3 is connected to the end piece 10, in which the coupling element 12 is inserted. As mentioned in the foregoing, the coupling element 12 has, at its free end, engagement means in the form of claw-coupling elements with teeth 13 for engaging corre¬ sponding engagement means in the form of grooves 14 (see Figs 1 and 6) on adjoining curve segments 6. The coupling element 12 is rotatably mounted on the supporting rod 7 extending between the ends of the curve 1.
Figs 4-6 illustrate an individual curve segment 6, whose design will be described in more detail below. As appears from Fig. 5, the curve segment 6 consists of a central circular-cylindrical portion 15 which on both sides may merge into a frustoconical portion 16 and 17, respectively, having a very slightly decreasing conicity in the direction away from the central cylinder portion 15. The slight conicity may be motivated by reasons of manufacturing technique, for instance when the curve segments 6 are made of plastic. If so, the forming tool must have a certain draft angle.
It further appears from Fig. 5 that the curve seg- ment 6 is not mirror-symmetrical with respect to its cen¬ tre plane perpendicular to the drawing, but the teeth 13a at one end are slightly offset in the circumferential
direction in relation to the teeth 13b at the other end. As a result, also the corresponding grooves 14a and 14b, respectively, are offset in this fashion. Tests have shown that the torque transfer is improved if the circum- ferentially-spaced teeth 13 are offset in this fashion, as compared with what would have been the case if the teeth had been arranged opposite to each other. Prefer¬ ably, the offset corresponds to approximately half the thickness of a tooth 13. Fig. 4 illustrates how the teeth 13 (eight in this embodiment) of the curve segment 6 are arranged at equal angular pitch with respect to the centre axis C of the curve segment 6. It furthermore appears from Fig. 4 that the teeth 13 are of increasing thickness in the radial direction away from the centre axis C. This design results in reliable engagement with the corresponding grooves 14 of adjoining curve segments 6. Furthermore, every tooth 13 is bevelled (at 18).
The curve segment 6 has a central opening 19 forming a supporting surface and having a diameter which slightly exceeds that of the supporting rod 7, thereby enabling appropriate mounting thereon. In a preferred embodiment, the supporting rod 7 is made of metal, while the curve segments 6 are made of rigid plastic. With such a choice of material, the friction between the internal mounting surface 19 of the curve segments 6 and the outside of the supporting rod 7 is very low.
Fig. 6 clearly illustrates the "piece-of-pie shape" of the teeth 13 of the curve segment 6. Furthermore, it appears that the teeth 13 project in parallel with the centre axis C of the curve segment 6 and extend radially in relation to this axis. The teeth 13 are of slightly decreasing thickness in the direction axially away from the centre plane of the curve segment 6 (cf. Fig. 5) . Each tooth 13 may thus be considered to be "frustoconi- cal", the "conicity" decreasing in the direction away from the centre plane.
In practice, it has been found that there should be a certain play between the engagement means of adjoining curve segments 6, i.e. between the teeth 13 of one curve segment 6 and the corresponding grooves 14 of an adjoin- ing curve segment 6. The shape of the grooves 14 is thus adapted to that of the teeth 13, such that there is a suitable play. However, the play should not be so great as to be undesirable and thus risk jeopardising the func¬ tion. It will be appreciated that a curve of the above type has a great many advantages. Since the curve seg¬ ments may advantageously be of equal size and the same shape, the curves can be easily standardised and modu¬ larised as desired. If so, the number of curve segments is directly proportional to the aimed-at curve angle and radius. The curvature of the supporting rod is adjusted according to need.
In tests, excellent results have been achieved with as small radii as 150-200 mm, suspended carriages having in reliable fashion been propelled through a curve of the type shown in Fig. 1. There are no major energy losses, and the construction is on the whole completely insensi¬ tive to such low and high temperatures as were discussed by way of introduction. Thanks to the permanent engage- ment between the curve segments, the propulsion by rota¬ tion through the curve is extremely reliable. Description of Further Embodiments
It is to be understood that the engagement means of the curve segments can be otherwise designed than has been described in the foregoing. Naturally, the design of the engagement means is not of decisive importance in the invention, but what matters is that the torque is reliably transferred from one curve segment to the next through the curve. As a result, the propulsion by rota- tion is transferred from the one shaft to the next.
In a variant not illustrated in the drawings, the end portions of the curve 1 shown in Fig. 1 are slightly
modified, in such a way that a few additional curve seg¬ ments 6 are arranged in the straight extension of the curve 1 in the direction of the respective shafts 2, 3. Thus, the engagement between the two one-sided coupling elements 11, 12 and the two adjoining double-sided curve segments 6 occurs in a straight part of the track, which in operation has been found to reduce the noise generated as a result of the engagement between the above coupling components. As an alternative to the internal mounting of the curve segments achieved with the aid of the supporting rod described above, one may resort to external mounting. If so, the curve segments are placed in some sort of U- shaped cradle following the curvature of the curve. The curve segments are kept in place by external roller bear¬ ings (not shown) .
In another embodiment (not shown), the curve seg¬ ments are interconnected by means of central ball-and- socket joints, which basically replace the supporting rod, in which case relatively few external support bear¬ ings are required.
Finally, it should be emphasised that the invention is in no way restricted to the propulsion of suspended load carriers having rollers that are in frictional and rolling contact with the shafts. The invention is equally applicable to propulsion shafts with a spiral groove (cf. US-A-3, 850,280, Fig. 1), in which are engaged hook means associated with load carriers. To ensure safe and reli¬ able propulsion of such a hook-suspended load carrier, the curve suggested according to the invention is pro¬ vided with a corresponding spiral groove, which is achieved by providing an inclined groove on the circum¬ ferential surface of each curve segment. The curve seg¬ ments are then arranged successively in such a manner that their inclined grooves form a helical extension of the spiral groove (not shown) of the adjoining propulsion shaft.
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