The invention relates to a method of producing a rail for a stairlift.
The rail for the stairlift will be mounted in a stair case which makes it necessary to make the rail in a curved form following the stair case. A carriage for moving a load up and down the rail will be provided with a gearwheel driven by a motor for engagement with the strip with the rack of the rail. The strip with the rack and the gearwheel have teeth which should substantially have the same intermediate distance or pitch P to allow for a smooth running operation. Having a curved rail the rack may be curved which may influence the pitch P of the teeth of the rack. This is especially the case if the rack is provided on an inside or an outside of a bend of the rail whereby the running operation of the rail may be deteriorated.
The carriage may be provided with a wheel constructed and arranged to run on a side of the strip to provide the required rotational stability for the carriage around the rail. The side of the strip should therefore be carefully formed to the required shape to allow a smooth running operation.
It is an objective of the invention to provide a rail which is easy to manufacture and allows a smooth running operation.
Accordingly, there is provided a method according to claim 1.
By individually positioning and mounting the pins on the support the pins can be individually positioned to assure a good matching with a gearwheel of a carriage for a smooth operation even if the rail is curved. By mounting a guiding strip against the pins a smooth guiding surface may be created for a guiding wheel of the carriage running over the rail assuring a smooth operation of the stairlift.
According to an embodiment mounting the first pin on the support comprises welding the first pin on the support with a welding device.
By welding a strong connection between the pin and the support is made.
According to a further embodiment welding comprises stud-welding the first pin by allowing an electric current to flow through the first pin and the support.
Stud-welding allows a fast and strong way to individually position and fasten the pin of a rack on a support whereby the position can be chosen such as to allow for a smooth running rack. The current provides the thermal energy for melting a portion of the pin and the support to form the weld pool in the welding process.
According to a further embodiment the pin is provided near its first end with a ceramic protector and the method comprises stud-welding the first end of the pin on the support.
The ceramic protector surrounds the pin at its first end to protect and support the weld pool, stabilize the arc and mold the displaced weld pool to form a weld collar. The method comprises removing the ceramic protector from the pin after the pin has been stud-welded to the support.
According to an embodiment welding comprises providing a shielding gas to the area surrounding the pin and the support.
The shielding gas protects the welding material from the surrounding air which may cause the welding pool to oxidize. The shielding gas may comprise argon.
According to an embodiment welding comprises one welding method out of the group of laser welding, spot welding, friction welding, induction welding, MIG welding, TIG welding, oxyacetylene welding and ultrasonic welding to weld the first pin on the support. Laser welding is a viable alternative for stud welding. Alternatively, spot welding, friction welding, induction welding, MIG welding, TIG welding, oxyacetylene welding or ultrasonic welding may be used.
According to an embodiment mounting the first pin on the support comprises drilling a hole in the support, followed by one of:
By screwing or riveting a strong connection can be made between the support and the pin. By screwing the pin may be releasable from the support.
According to an embodiment mounting the first pin on the support may comprise shooting the pin on the support.
By shooting with powder or air a very quick way of mounting the pins on the support is created.
According to an embodiment the pin has a circular cross-section.
The circular cross-section makes it possible for a gearwheel to run on the side of the pins. Running on the side of the pins makes a very compact design of the stairlift possible.
According to an embodiment the method comprises providing a bush over the pin.
The bush may be provided with harder metal than the pin so that wear of the pin is decreased.
According to an embodiment the method comprises creating the pins at a regular pitch P.
The regular pitch makes it possible for a gearwheel with teeth to engage with the pins.
According to an embodiment repeating b to c for subsequent pins comprises:
In this way a rail with pins at a regular distance are created making it possible for a gearwheel with teeth at a pitch P to engage with the pins of the rack.
According to an embodiment positioning the second pin on the curved support comprises taking into account the curvature of the support and the distance the gear wheel is running from the surface of the support to determine the position of the second pin with respect to the first pin on the support.
During positioning of the pins on the support the curve of the support and the distance of the gear wheel with respect to the support is taken into consideration to assure a smooth running gearwheel.
According to an embodiment the method comprises:
In this way pins at regular distances are created making it possible for a gearwheel with teeth at a pitch P to engage with the pins of the rack.
According to an embodiment of the method the support has one of a circular, elliptical, and polygonal cross section.
The support thereby provides a good surface for the carriage to run over it.
According to an object there is provided a rail according to claim 12.
According to an object of the invention the pins have a circular cross-section and the pins are stud-welded at a first end with their circular cross-section on the support.
The circular cross-section makes it possible for a gearwheel to run on the side of the pins.
According to the invention, mounting a guiding strip against the pins comprises welding the guiding strip near a second end of the pin.
The guiding strip provides for guiding of a guiding wheel provided to the carriage at a distance from the rail to prevent rotation of the carriage around the rail. Since the guiding strip is welded near the second end of the pin the forces on the guiding strip are smaller than would be the case if the guiding strip is mounted close to the support. Optionally, the guiding strip may be welded at the top of the pins.
As an alternative option according to the invention, mounting a guiding strip against the pins comprises welding the guiding strip on a side of the pin.
Welding the guiding strip on a side of the pin allows for a strong connection between the pins and the guiding strip.
According to a further embodiment there is provided a stairlift to move a load, such as a person or goods along a staircase, the stairlift comprising:
The carriage may be provided with a gearwheel for engagement with the pins on the rail and driven by a motor, the gearwheel having substantially the same pitch P as the pins. In this way pins with regular pitch P are created making it possible for a gearwheel with teeth at a pitch P to engage with the pins of the rack.
According to an embodiment the carriage is provided with a guide wheel for guiding the carriage along the guiding strip mounted to the pins.
The guiding strip provides for guiding of the guiding wheel at a distance from the rail to prevent rotation of the carriage around the rail. Since the guiding strip is a pin length away from the rail the forces on the guiding strip are smaller than would be the case if the guiding strip is close to the support.
Embodiments of the stairlift will be described by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:
The rail is provided with a guiding strip 15 welded near a second end of the pins 9. The guiding strip may be welded on top of the second end of the pins. The guiding strip 15 provides for guiding of a guiding wheel 17 provided to the carriage at a distance from the support 7 to prevent rotation of the carriage around the rail. Since the guiding strip may be welded near the second end of the pin the forces on the guiding strip 15 may be limited. Optionally, the guiding strip may be welded at the side of the pins which makes an easy and strong connection possible.
The rail 3 for the stairlift 1 may be manufactured by:
Stud-welding allows a fast and strong way to individually position and mount the pins 9 of the rack 11 on the support 7 whereby the position can be individually chosen along a line on the support 7 such as to allow for a smooth running rack 11. The stud-welded pins may be welded at a regular distance from each other for accommodating a gear wheel to run on its side. The regular distance makes it possible for the gearwheel 13 to successfully engage with the pins 9. During stud-welding a current may be allowed to flow through the pin and the support. The current provides the thermal energy for melting a portion of the pin and the support to form the weld pool in the welding process such that a rigid weld is formed. After the weld pool has been created the pin may be pressed in the pool.
A shielding gas may be provided to the area surrounding the pin and the support during stud-welding. The shielding gas protects the welding material from the surrounding air circumventing that the welding pool oxidizes. The shielding gas may comprise argon.
Welding may comprise laser welding the pin on the support. Alternatively, spot welding, friction welding, induction welding, MIG welding, TIG welding, oxyacetylene welding or ultrasonic welding may be used.
Repeating b to d for subsequent pins comprises:
In this way pins positioned at regular distances along a line are created making it possible for a gearwheel with teeth at a pitch P to engage with the pins of the rack. The distance between the pins should be N (natural number) times a pitch P at a place on the pin where the gearwheel 13 is engaging the pins 9 of the rack 11.
The latter is important if, for example the support is making a curve in plane parallel to the pins. This causes the pins to be oriented not parallel to each other but a little angled with respect to each other. It is important that the distance between the portion of the pin where the gearwheel is running is at a fixed distance (pitch) with respect to the other pins. During positioning and mounting the second pin on the support substantially at a distance of N (natural number) times a pitch P from the first pin the curve of the support and the distance of the gear wheel with respect to the support is taken into consideration to assure a smooth running gearwheel.
The method further comprises:
The support 7 may have one of a circular, elliptical, and polygonal cross section. The support thereby provides a good surface for the carriage to run over it.
Again, it is important that the distance between the portion of the pin where the gearwheel is running is at a fixed distance (pitch) with respect to the other pins. During positioning of the pins on the support the curve of the support and the distance of the gear wheel with respect to the support will be taken into consideration to assure a smooth running gear wheel.
A stairlift to move a load, such as a person or goods along a staircase making use of the rail 3. The stairlift comprising:
According to a further embodiment the pin is provided near its first end with a ceramic protector and the method comprises stud-welding the first end of the pin on the support.
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Alternatively, the pins may be mounted on the support by drilling a hole in the support, cutting a screw thread in the sides of the hole and screwing a pin with a screw thread in the hole.
Alternatively, the pins may be mounted on the support by shooting the pins on the support. Powder actuated tools such as available from Hilti™ from Lichtenstein or compressed air actuated tools can be used to shoot the pin in the support.
Alternatively, the pins may be mounted on the support by drilling a hole in the support, providing a blind rivet (i.e. pop rivet) in the hole. Subsequently a specially designed tool may be used to draw a mandrel in a blind end of the rivet. This expands the blind end of the rivet which secures it in the hole of the support. Thereafter the mandrel may snaps off but the rivet will be kept in its place by the expanded blind end.
Other mounting techniques such as friction welding , ultra-sonic welding, rotation welding, spot welding or laser welding may be used to mount the pins on the support.
Multiple pins 9 may be individually positioned and mounted on the part of the support 8 by any suitable mounting method. For example, the pins 9 may be mounted by welding e.g. stud-welding, laser welding, spot welding, friction welding, induction welding, MIG welding, TIG welding, oxyacetylene welding or ultrasonic welding them on the support at a fixed distance pitch P from each other. The pins 9 may also be mounted by drilling a hole in the support 8 and screwing a threaded pin in the hole or by providing a blind rivet in the hole. The pins 9 may have a circular cross-section.
A hollow bush 10 may be provided over the pin 9. The pins 9 may be welded at a first end with their (circular) cross-section on the support part 8 forming a rack 11. By positioning the pins 9 along a line on the support part 8 and by providing the circular bush 10 around the pins 9 it becomes possible for a gearwheel to run on the side of the bush 10. Running on the side of the bush 10 makes a very compact design of the stairlift possible because the gear wheel can be positioned very close to the support. The bush 10 may at least be partially surrounding the pin 9 and in use be in contact with the gearwheel. The bush 10 may be hardened (with respect to the hardness of the pin) so that it doesn't significantly wear when the gearwheel is running over it. The pin 9 may be softer relative to the bush 10 giving it a higher tensile strength increasing strength of the overall construction. Optionally, the bush may be rotatable mounted around the pin.
The rail 3 is provided with a guiding strip 15 welded near a second end of the pins 9. The guiding strip may be welded on top of the second end of the pins 9. The guiding strip 15 provides for guiding of a guiding wheel provided to the carriage at a distance from the support to prevent rotation of the carriage around the rail 3. Since the guiding strip may be welded near the second end of the pin 9 the forces on the guiding strip 15 may be limited. The guiding strip 15 may also assure that the bushes 10 are kept around the pins 9. The guiding strip 15 may allow the bushes 10 to rotate around the pins 9.
Alternatively, the guiding strip 15 may be welded to the bushes 10 in which case the bushes cannot rotate around the pin 9.
The method of producing a rail 3 for a stair lift with a bush 10 may comprise:
Subsequently a guiding strip 15 may be mounted against the pins. The guiding strip mounted on the pins may keep the bushes 10 at their place on the pins. If it is not necessary that the bushes 10 are able to rotate around the pins the guiding strip may also be welded on the bushes. However it may be preferred that the guiding strip is welded on the pins so that the hardened bush is not softened by the welding step.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting, but rather, to provide an understandable description of the invention.
The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language, not excluding other elements or steps). Any reference signs in the claims should not be construed as limiting the scope of the claims or the invention.
It will be apparent to those skilled in the art that various modifications can be made to the device and method without departing from the scope as defined in the claims.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.