Patent Description:
The transporting system allows carriages to run on tracks to transport loads between various processing stations, for example along an assembly line.

In transporting systems, the track generally consists of straight and curved portions that form both closed and open paths, and are often mounted on a base plate to provide a support.

The carriages that run on these tracks have rollers that rest on the sides of the track, and must be mounted so as to maintain a tight tolerance between the rollers and the profiles of the track along the entire guide system, thus providing a correct adhesion between them to allow transport.

In fact, the carriages, mounted on a straight portion and having the rollers positioned with a suitable fixing (clearance) for a straight portion, due to the variation in the clearance, when travelling along the curved portions of the track can have problems of the rollers rubbing or sticking during movement of the carriage along the track.

Examples of guide systems of the type described above can be found in the documents <CIT> and <CIT>.

The document <CIT> discloses a carriage in which three shaped rollers are mounted in fixed position with respect to the carriage and the width of the track between the two profiles varies so as to maintain a tight tolerance between the rollers and the profiles of the track along the whole of the guide system, in particular along the portions of the track that join curved and straight portions or between curves with variable radii. In this case, positioning of the rollers of the carriages requires extremely accurate adjustment during assembly. A regulation of this type is typically produced, through the use of specific instruments, by skilled technicians and cannot be entrusted to the normal operators of the automatic machines to which the guide systems are typically applied. Moreover, the intervention of skilled technicians is also required to remove the carriages from the closed paths for ordinary cleaning and/or maintenance operations.

To produce tracks with variable width to maintain the clearance between the carriage and the track constant both in the connecting portions between straight and curved portions and in the connecting portions between curves with different radii, an extremely precise and difficult calculation is required.

The document <CIT> describes a carriage with three rollers, which moves on a track that lies on a vertical plane, at least one of which is provided with a pressure device, which moves along a track of variable width to be able to freely manage the coupling pressure of the rollers on the profiles of the track.

Moreover, in the patent <CIT> the rollers are cylindrical and the coupling profiles on the sides of the track are straight along a line orthogonal to the plane on which the track lies. Maintaining the carriages in a direction orthogonal to that of the plane on which the track lies is delegated to other idle rollers mounted rigidly on the carriage.

Due to the pressure devices and the use of cylindrical rollers, solutions such as the one disclosed by the patent <CIT> allow the use of tracks with shape and tolerances such as to simplify their design and production. However, given the shape of the rollers and of the profiles, other elements are required to maintain the carriages on the tracks.

Moreover, it can be noted in general that in guide systems with carriages provided with pressure devices, if the resultant of the external forces acting on the carriage were to exceed the force generated by the pressure device, one or more rollers would detach from the track.

Therefore, in these systems the force exerted by the pressure system must be calculated as a function of the loads acting on the carriage in operation. If this pressure is not managed, for example, with variation of the width of the guide, it is constantly present on the rollers even when the carriages are not subjected to the maximum external loads.

The above causes the rollers to be loaded at all times, even in situations in which this is not necessary, limiting the useful life of the components and/or making it necessary to oversize the mechanical members.

Although the solution disclosed in the patent application <CIT> simplifies production of the carriage with respect to the state of the art, the design and production of the profiles of the tracks is more complicated. Imprecisions in calculation or errors in production for the profiles of the tracks in the order of hundredths of millimetre can cause clearance, rubbing or sticking of the rollers during movement of the carriage along the track. The phenomena described limit the useful life of the rollers and of the tracks.

Besides the extreme precision of calculation and production of the profiles of the tracks, the rollers of the carriages, as described in the patent application <CIT>, require extremely accurate adjustment of the position during assembly. An adjustment of this type is typically implemented through the use of specific instruments, by skilled technicians and cannot be entrusted to the normal operators of the automatic machines to which the guide systems are typically applied. This means that any removal of the carriages from the closed paths for ordinary cleaning and/or maintenance operations also requires the intervention of skilled technicians.

Moreover, the carriages and the tracks, as described in the <CIT>, do not allow any adjustment of the coupling load between rollers and profiles through a specific variation of the thickness of the rails as described in the patent <CIT>.

Also the document <CIT> discloses a system for transporting materials according to the preamble of claim <NUM>. In particular, the document discloses a mobile unit wherein a platform is supported upon track by a plurality of rollers mounted in pairs on a plurality of trucks.

The object of the present invention is to provide a system for transporting materials by means of track and carriages capable of optimal movement of carriages along a straight and curved track.

Another object is that of providing a system capable of offsetting imprecisions in design or machining errors in the parts of which the guide systems are composed.

A further object is that of providing a system capable of limiting the coupling pressure between rollers and profiles of the track.

Yet another object is that of providing a system capable of disassembling and reassembling the carriages from/on the track, for cleaning and/or maintenance operations, without the use of specific instruments.

In accordance with the present invention, these objects and others still are achieved by a system for transporting materials by means of track and carriages according to claim <NUM>.

Further features of the invention are described in the dependent claims.

The advantages of this solution with respect to the known art solutions are various.

The possibility of movement of one roller, with respect to the other two, greatly simplifies the design and production of the tracks and due to the pressure means, as produced in the present invention, it is possible to limit the coupling pressure between rollers and profiles of the track.

A possible positioning of the pressure means centrally and symmetrically to the carriage provides an equal pressure at the two opposite rollers.

This makes it possible to obtain a carriage with at least one roller that can carry out a translation movement with respect to the carriage. The translation motion takes place along an axis preferably parallel to the plane of the guide system and orthogonal to the direction of forward movement of the carriages along the track.

A pressure element acts along the translation axis.

A stop is also arranged along the translation axis to unilaterally limit the translation movement of the roller.

Through a threaded ring nut, micrometric adjustment of the position of the stop is possible.

A spring has the sole purpose of ensuring coupling between rollers and tracks with a minimum preload that allows the rollers to run without rubbing, offsetting any imprecisions in calculation or errors in production for the profiles of the tracks.

The unilateral constraint offsets any external forces regardless of the force of the spring; in fact, the distance between centres of the rollers can only become narrower due to the spring, but cannot become wider due to the stop.

Acting on the width of the guide it is possible to narrow it until creating a zone in which, overcoming the preload spring and moving the stop towards its end of travel, it is possible to easily remove the carriage without the aid of mechanical tools.

The features and advantages of the present invention will be evident from the following detailed description of a practical embodiment thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein:.

With reference to the accompanying figures, a system for transporting materials by means of track and carriages, in accordance with the present invention, comprises a track <NUM>, and one or more carriages <NUM> having rollers engaged with the track <NUM> and which can run thereon.

The track <NUM> can have any form with straight portions, internal and external curves, and can have both closed and open paths.

In accordance with the present invention, the track <NUM> is profiled on the lateral sides, in particular the section of the track <NUM> is T-shaped so that it has two profiles <NUM> or lateral sides at the top of the track <NUM>.

The track <NUM> has a width that is preferably constant both in the straight and in the curved portions.

The carriage <NUM> is formed of a trapezoidal or rectangular shaped frame <NUM> having an oblong shaped central opening <NUM>, with a terminal widening <NUM>, to facilitate adjustments and/or assembly.

The frame <NUM> has two through holes <NUM> and <NUM> positioned longitudinally to the frame <NUM> and will therefore be orthogonal to the direction of the track <NUM>. Positioning of the holes <NUM> and <NUM> is central with respect to the carriage <NUM>.

Two rollers <NUM>, having an internally shaped (recessed) profile designed to coact with the external profiles <NUM> of the track <NUM>, are fixed stably at the two sides of the hole <NUM>, on one side of the frame <NUM>.

The carriage <NUM> comprises a cylindrical bar <NUM> terminating on one side with an enlargement <NUM> that has a vertical through hole <NUM>. The bar <NUM> has a size such that it can run inside the two holes <NUM> and <NUM> and a length such that the enlargement <NUM> is external to the frame <NUM>. The enlargement <NUM> can be omitted if the bar <NUM> has a size sufficient to accept the hole <NUM>.

A roller <NUM> is fixed to the through hole <NUM> of the bar <NUM>, by means of a vertically positioned bolt <NUM>. The roller <NUM> also has an internally shaped profile, designed to coact with the profiles <NUM> of the track <NUM>.

It should be noted that in this case the rollers <NUM> and <NUM>, just as the profiles <NUM> of the track, are shaped so as to constrain the carriages <NUM> to the track <NUM>, leaving them free to move in the sole direction of the track <NUM>, and therefore are supported vertically without other means besides the rollers <NUM> and <NUM>.

The rollers <NUM> and <NUM> are positioned on the carriage to form an isosceles triangle at the vertex of which the roller <NUM> is positioned.

The bar <NUM> is smooth externally but has a threaded portion.

The threaded portion <NUM> is located on the bar <NUM> at the opposite end to that of the enlargement <NUM>, and positioned inside the frame <NUM>.

The carriage <NUM> comprises a ring nut <NUM> which is screwed onto the threaded portion <NUM>.

The ring nut <NUM> is preferably of the self-locking type with nylon insert, so as to be able to tighten it and block it in the desired position.

The carriage <NUM> further comprises a spring <NUM> which is placed on the bar <NUM> and has a block <NUM> that retains the spring <NUM> towards the hole <NUM> where it abuts against the inside the frame <NUM>. The block <NUM> is positioned between the opening <NUM> and the widening <NUM>. In the point in which the opening <NUM> opens into the widening <NUM>, in the direction of the rollers <NUM>, it has an undercut <NUM> where the block <NUM> is positioned. The block <NUM> comprises a lower portion that abuts against a lower portion of the frame <NUM> and an upper portion that is inserted into the opening <NUM> which does not allow the rotation thereof.

The ring nut <NUM> pushes the block <NUM> against the undercut <NUM> and blocks the spring <NUM> between it and the end of the frame <NUM> towards the hole <NUM>. The block <NUM> with the ring nut <NUM> also blocks the extension of the bar <NUM>, beyond the position established by the ring nut <NUM>, in the direction of the roller <NUM>. While a movement of the bar <NUM> in the opposite direction, retained by the spring <NUM>, is possible as the ring nut <NUM> has space to move back, towards the rollers <NUM>, into the widening <NUM>.

Mounting of the carriage <NUM> is implemented by inserting the bar <NUM> inside the hole <NUM> and before inserting it into the hole <NUM> the spring <NUM> is inserted on the bar <NUM>, the block <NUM> and the ring nut <NUM>, the last part of the bar <NUM> is inserted into the hole <NUM> and the ring nut <NUM> is then screwed onto the thread <NUM>, which blocks the assembly.

The spring <NUM> acts along the axis defined by the bar <NUM>, providing a pressure element given by the type and by the length of the spring <NUM>.

The pressure of the spring <NUM> determines the load of the rollers <NUM> and <NUM> on the track <NUM>.

To facilitate the thrust and disengagement operation of the roller <NUM>, it is possible to provide a seat <NUM> at the end of the bar <NUM>, for insertion of a common hexagonal key. Due to the preload and to the profiles of the rollers <NUM> and <NUM>, a self-alignment of the carriage <NUM> on the track <NUM> also occurs.

Moreover, positioning of the bar <NUM> at the centre of the carriage and positioning of the rollers <NUM> at the sides of the bar <NUM> and at the same distance from the bar <NUM> make the preload exactly the same on the two rollers <NUM> allowing the carriage <NUM> to run more smoothly on the track <NUM>.

Once the carriage <NUM> has been positioned on the track <NUM>, the spring <NUM> provides the rollers <NUM> and <NUM> with a preload so as to prevent slipping of these rollers <NUM> and <NUM>.

The carriage <NUM> cannot detach from the track <NUM> even if a very high load is applied thereto, due to the block <NUM> that does not allow the rollers <NUM> and <NUM> to move away from each other.

Claim 1:
A system for transporting materials by means of track and carriages comprising: a track (<NUM>); at least one carriage (<NUM>) engaged with said track (<NUM>); said at least one carriage (<NUM>) having a roller (<NUM>) engaged with one side of said track (<NUM>) and a pair of rollers (<NUM>) engaged on the opposite side of said track (<NUM>); said pair of rollers (<NUM>) is constrained to said carriage (<NUM>); said roller (<NUM>) is fixed to a bar (<NUM>); said bar (<NUM>) can translate with respect to said carriage (<NUM>) and comprises pressure means (<NUM>) to press said roller (<NUM>) against said track (<NUM>); said bar (<NUM>) comprises a unilateral block that does not allow the extension of said bar (<NUM>) with respect to said carriage (<NUM>) beyond a pre-set distance; said unilateral block comprises: a threaded portion (<NUM>), positioned on said bar (<NUM>), on which a ring nut (<NUM>) can be screwed; a block (<NUM>) sliding along said bar (<NUM>) constrained to said carriage (<NUM>) by means of said ring nut (<NUM>); where said pressure means (<NUM>) are positioned between said block (<NUM>) and said roller (<NUM>); said carriage (<NUM>) consists of a trapezoidal or rectangular shaped frame (<NUM>) having a central opening (<NUM>, <NUM>); said central opening (<NUM>, <NUM>) comprises an oblong shaped central opening (<NUM>), with a terminal widening (<NUM>); characterised in that said block (<NUM>) is positioned between said opening (<NUM>) and said widening (<NUM>); said block (<NUM>) comprises a lower portion that abuts against a lower portion of said frame (<NUM>) and an upper portion that is inserted into said opening (<NUM>).