Patent Application
20200340549
The invention relates to a rigid chain link and to a rigid chain that is formed of such links and is capable of working rigidly in compression.
The majority of known chains are designed with a free shape so as to work in traction between two coupling points. They are made up of links, typically made of steel, that are each interlinked with two adjacent links that are closed on themselves. Traction exerted on end links tensions the chain and allows it to be used in traction. In the traction position, the different links are aligned and form approximately a straight line. When the traction is released, the chain deforms under the effect of gravity and can then be stowed in a roll or as a stack of any shape.
A known chain variant is the articulated chain of the bicycle chain type. It differs from the chain of free shape in that the links have a particular shape formed by two pins connected by two lateral plates. This allows the chain to deform approximately in a plane, namely the plane of the crankset, but to resist deformation in a direction out of the plane of the crankset.
The two abovementioned types of chain can only work in traction and are not designed to exert thrust on an object, for example in order to raise or move a load.
For this purpose, chains known as rigid chains have been provided, which are provided with links that are articulated with respect to one another but are configured to be able to absorb a compression force without deforming.
The document EP 1006074 B1 (Serapid) describes such a rigid chain. It is made up of a set of links connected together. Each link has metal lateral plates having two orifices situated on one side of the plates, and a third orifice situated on the opposite side. The three orifices in each link form an isosceles triangle. The two orifices of the first side receive articulation pins that allow the articulation of the links with respect to one another. The third orifice receives a drive pin provided with a drive roller that cooperates with the teeth of a drive gear mechanism. In the straight position of the chain, two adjacent links are locked with respect to one another with the aid of notches that are formed in the plates and are positioned on the drive pins.
It has been found that this structure is relatively complex and requires the manufacture and assembly of a large number of different parts. Moreover, given that the parts are mainly metallic, this chain has a high weight. Moreover, it is not suitable for use in corrosive environments because the metal parts would degrade, threatening the stability of the chain.
The general aim of the invention is to provide a chain link for a rigid chain that is particularly simple and makes it possible to obtain a rigid chain that is inexpensive to manufacture and assemble, while being suitable for raising or moving heavy loads over a long distance.
The specific aim of the invention is to provide a chain link and a rigid chain that can be used in a wide variety of environments, including corrosive environments such as chlorinated water or salt water, for example in a swimming pool environment.
In principle, the invention provides a link and a series of links that are juxtaposed to form a chain, each link, apart from the end links, being connected to two adjacent links and being articulated with respect to the latter by a rotary pin.
The links are designed such that the rotation of one link with respect to its neighbor(s) is guided between end positions, and in one of these end positions, corresponding to the working position of the chain, the adjacent links are aligned in a straight line, whereas in the other positions, the assembled links form a curved line. In the working position, when the links are aligned, two adjacent links have contacting faces designed to be able to absorb a compression force, such that the chain as a whole can behave like a beam absorbing a compression force parallel to the direction of alignment of the links. Moreover, the links are designed in a rot-proof and corrosion-resistant material so as to be able to be used in a variety of environments, including corrosive liquids.
Therefore, a first subject of the invention is a link for a rigid chain, said link having a body that is approximately in the shape of a fork and is provided with a heel connected by a base to two parallel flanges separated by a space intended to receive the heel of an adjacent link, the heel and each flange having an orifice configured to receive a joint rotary pin for articulating a link with respect to an adjacent link.
According to the invention, the base has, on either side of the heel, two parallel shoulders configured to form a stop with respect to the ends of the flanges of an adjacent link. Preferably, the amplitude of articulation of two adjacent links is possible in an angular range limited to 90°, the angle of 0° corresponding to the alignment of the adjacent links along a straight line.
The end faces of the flanges are parallel to the faces of the shoulders and perpendicular to the compression force that is exerted on the links in the working position. In this way, when the adjacent links are aligned in a straight line, the shoulders of one link bear against the end faces of the flanges of an adjacent link, thereby making it possible to absorb a large compression force.
According to an advantageous embodiment, each flange and the heel of a link have an approximately rectangular shape with a rounded corner situated in the vicinity of the rotary pin.
Preferably, the distances between the rotary pin and the two perpendicular sides of the flanges and the two perpendicular sides of the heel that are adjacent to the rotary pin are the same, thereby allowing a maximum angular travel of 90° between two adjacent links.
Advantageously, the rotary pin is perpendicular to the main plane of symmetry of the link and offset toward the rear side of the link that is provided with the rounded portions.
Preferably, the radius of curvature of the rounded corners of the flanges and of the heel is greater than the distance between the rotary pin and the two perpendicular sides of the flanges and the two perpendicular sides of the heel that are adjacent to the rotary pin.
According to an advantageous embodiment, the heel has an orifice that receives a threaded fastening screw, the end of which is fitted into a tapped orifice in the rotary pin so as to secure the body of the link and the rotary pin thereof in terms of rotation. The rotary pin and the fastening screw thereof are made for example of stainless steel.
According to an advantageous embodiment, the body of the link is made of plastics material mixed with reinforcing fibers, notably glass fibers.
The body of the link is obtained by molding/injection molding or by rotational molding, or by 3D printing.
Alternatively, it could be obtained by assembly of a heel, a base and added flanges, but this embodiment would undoubtedly be more expensive.
A further subject of the invention is a rigid chain, which has a linear assembly of links according to the invention, such that the heel of one link is fitted into the space situated between the flanges of an adjacent link, a joint rotary pin being inserted into the orifices in the flanges of a link and the orifice in the heel of an adjacent link.
According to a particularly stable embodiment, the rigid chain has a linear assembly of chain elements, each chain element being made up of several unitary links as described above that are connected by a single rotary pin, a part of the rotary pin remaining free in order to allow engagement with a sprocket for driving the chain.
The invention will be understood better with the aid of the detailed description and the drawings, in which:
Reference is made to
The heel 3 and each flange 5 have an orifice configured to receive a joint rotary pin 7 (not shown in this figure) for articulating a link with respect to an adjacent link.
The heel 3 and the flanges 5 have a generally parallelepipedal shape. The link 1 is symmetric with respect to a main plane of symmetry 8 passing through the median plane of the heel 3 and to the middle between the two flanges 5.
The base 4 has, on either side of the heel 3, two parallel shoulders 9 that are configured to form a stop with respect to the end faces 10 of the flanges of an adjacent link, when these two links are aligned. It is this stop that makes it possible to lock the links together and to absorb the compression forces to which they will be subjected.
To this end, the end faces 10 of the forks are parallel to the faces of the shoulders 9 and perpendicular to the compression force that is exerted on the links in the working position, in a direction parallel to the main plane of symmetry 8.
As can be seen in the central part of
The orifice 19 is formed in the heel 3 of the link, and the orifices 20, 21 are formed in the flanges 5, as can be seen in the right-hand part of
Preferably, the distances d1, d2 between the center of the orifices 19, 20 and the sides 14, 15, 16 of the flanges which are next to said orifices are all the same. Moreover, the centers of the rounded portions 17, 18 correspond respectively to the centers of the orifices 19, and (20, 21). Furthermore, the radii of curvature of the rounded portions 17, 18 are greater than the radius of the various orifices 19, 20, 21. This ensures that the rotation of two adjacent links is limited to an angular range of between 0° and 90°, the angle of 0° corresponding to the aligned position of the links, and thus to the stable working position of the chain.
According to a preferred embodiment of the link 1, the heel 3 also has a tapped orifice 22 that receives a threaded fastening screw (not shown), the end of which is fitted into a tapped orifice (not shown) formed in the rotary pin 7 so as to secure the body 2 and the rotary pin 7 thereof in terms of rotation.
According to an advantageous embodiment, the body 2 of the link 1 is made of plastics material mixed with reinforcing fibers, notably glass fibers, in a quantity to be determined depending on the desired mechanical strength.
In order for the link 1 to be able to be used without being damaged in a corrosive environment, it is useful for the rotary pin 7 and the fastening screw fitted therein to be made of stainless steel or some other corrosion-resistant material.
Several manufacturing methods are conceivable for manufacturing the body 2 of the link according to the invention. For economic, high-volume production, a method of injecting the plastics material charged with fibers into a mold and then demolding the parts after curing could be used. Alternatively, it may be possible to use techniques, known per se, of rotational molding, 3D printing, machining, or assembly of a heel 3, a base 4 and added flanges 5.
As shown in
In operation in a working position, the faces 10 of the flanges of a given link butt against the shoulders 9 of an adjacent link, thereby ensuring a sufficient contact area for absorbing the compression force.
The fact that the rotary pins 7 are offset toward the rear side 14 of the chain, toward which the chain can be curved, ensures stable locking of the chain when it is in a straight position.
In order to form a chain 33 as shown in
This provision makes it possible to reinforce and stabilize the chain thus formed even further, but without changing the configuration of each unitary link 1.
Of course, if necessary, it is possible to mount more than two links 1 on one and the same pin 7, thereby further increasing the stability of the chain 33 with respect to any lateral forces.
In order to increase the stability of the chain 23, 33 in the working position, it may be useful to provide one or both of its ends with a foot 27. In the example shown in
As shown in
The invention meets the aims set. The unitary chain link 1 has a particularly simple design allowing very economical mass production, in particular by injecting a plastics material reinforced with fibers into a mold. The materials used can be chosen easily to optimize the resistance of the links depending on the use environment.
Each unitary link 1 comprises only three parts, namely a body 2, a rotary pin 7, and a screw for fastening the rotary pin with respect to the body.
If necessary, and depending on the intended stability and compression forces, the chain formed by a linear assembly of links 1 can be doubled by using several, for example two, bodies 2 mounted in parallel on one and the same rotary pin 7.
With such a design, the rigid chain 23, 33 according to the invention is suitable for raising or moving heavy loads over a long distance. The actuating distance is limited only by the length of the chain.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19 04330 | Apr 2019 | FR | national |
