WO1996000183A1

WO1996000183A1 - Procedure for the manufacture of elevator guide rails

Info

Publication number: WO1996000183A1
Application number: PCT/FI1995/000365
Authority: WO
Inventors: Simo Mäkimattila
Original assignee: Kone Oy
Priority date: 1994-06-23
Filing date: 1995-06-22
Publication date: 1996-01-04
Also published as: AU2793695A; FI97969C; FI943044A; FI97969B; FI943044A0

Abstract

The invention relates to a procedure for the manufacture of an elevator guide rail consisting of a stock (1) and a guiding part (2). The cross section of the profiled guide rail is dimensioned in accordance with the bending moment of the guide rail and the dimensions of the elevator shaft and interfloor distance of the building and the thicknesses of the stock (1) and guiding part (2) are selected independently of each other and the stock (1) is stiffened.

Description

PROCEDURE FOR THE MANUFACTURE OF ELEVATOR GUIDE RAILS

The present invention relates to a procedure for the manu¬ facture of elevator guide rails as defined in the preamble of claim 1.

The requirements relating to the guide rails in an elevator system are mainly due to the demands of travelling comfort and the limitations caused by installation work. The most important functional requirement relates to the straightnεss tolerances of the guide rail. Straightness deviations in the guide rails give rise to lateral oscillation of the car. The higher the nominal speed of the car, the smaller the deviations from a geometric straight line that can be allowed.

The installation methods commonly used practically limit the rail length to about 5-6 m. The layout of rail fixing points influences the rigidity of the system, but the rigidity of the guide rail itself has a significance for the system as it determines the maximum distance between rail fixing points for the allowed rail deflection value. The rigidity of the rail depends on the form of its cross-section. The guide rails currently used are almost exclusively T-section rails.

The guide rails to be installed in the elevator shaft are selected by determining the allowed lateral deflection values of the rails on the basis of the mass and velocity of the elevator car or counterweight. A straight profiled guide rail has a constant flexural rigidity. If necessary, it is possible to increase the number of rail fixtures, which increase the rigidity of the rail by producing reactions of abutment with the building. The rigidity of the guide rails is adjusted to a value required by safety gear action. In the gripping situation, the elevator car is stopped from an overspeed by means of a safety gear interlocking with the rails. In buildings constructed of reinforced concrete, the guide rails are fixed by bolting or by means of fixing elements embedded in the concrete. If the building has a steel beam skeleton, then it is necessary to mount intermediate beams between the floors to ensure that the rails are sufficiently braced.

An example of previously known technology is the method currently used for the manufacture of profiled guide rails, which is based on hot or cold forming of steel, i.e. on a drawing and/or rolling process. These processes leave a relatively high residual stress in the material and require a separate correction process. In addition, the conventional manufacturing process involves the problem that the dimensional tolerances and straightness also depend on quality variations in the steel used, i.e. on the distribution of alloy components in the rail profile and on the divergence of alloy components between different manufacturing lots. "Rail profile" refers mainly to the cross-sectional form. In the conventional manufacturing process, the flow of metal during forming limits the cross-sectional form. The cross- sectional form has to be chosen to suit the forming process.

The object of the present invention is to eliminate the drawbacks referred to above. The procedure of the invention is characterized by what is presented in the characterization part of claim 1. Other embodiments of the invention are characterized by the features presented in the other claims.

The advantages achieved by the invention include the following:

- lower investment costs than in the current method - guide rails of different cross-sectional sizes and forms can be manufactured on the same production line

- normal commercially available plate steel or hot- rolled bands can be used as raw material

- flexible production of profiled guide rails of differ- ent cross-sectional forms is possible - directly applicable for use with current installation and rail mounting methods as the rail joint is made in the conventional manner

- in a welded guide rail, variations in the alloy compo- nents of the steel or local variations in strength have no effect on the straightness of the rail or on form defects deforming the structure

- the stock and the guiding part of the rail may differ from each other in thickness because the welding method does not involve geometric requirements as the rolling method does

- any metallic materials permitting fusion welding can be welded

- point formed application of heat - as compared with normal welding, the groove is narrow but deep

- guide rail cross-sections differing in thickness can be welded

- dissimilar metals can be welded together, e.g. steel/stainless steel

- welding can be performed using normal protective gas, depending on the materials

- the welded joint requires no finishing machining as the seam is narrow and only insignificant splashing of melt takes place

- installation requires less work because rail extensions are already made at the welding stage.

In the following, the invention is described by the aid of an example by referring to the attached drawings, in which

Fig. 1 presents a welded guide rail profile,

Fig. 2a, 2b and 2c present alternative forms of rail profile

Fig. 3 presents a welded profile with a machined facet or relief Fig. 4 illustrates the effect of flexural rigidity in the directions of the guiding part and the stock Fig. 5 illustrates the rail welding procedure Fig. 6 presents a laser welding apparatus

Fig. 7 illustrates the stages of guide rail manufacture.

Fig. 1 shows the cross-sectional form of a guide rail having a stock 1 stiffened by bending and a guiding part 2 which acts as a slide surface or in contact with roller guides and a safety gear. The welded joint is indicated by number 3. In a rail welded by means of a laser beam, it is possible to achieve a better straightness tolerance value than in a conventional guide rail. The improvement in the straighness and dimensional tolerances is based on the fact that the guide rail is essentially manufactured using engineering workshop methods. In laser welding, the essential working operations affecting the straightness of the guide rail are performed at room temperature and the thermal effect of the welding process itself is very small. During the assembly of the profiled guide rail, i.e. during the welding, the parts are mechanically held in place, so that the factors (=welding clamps) determining the accuracy of form can be more readily controlled. In a welded guide rail, variations in the alloy components of the steel or local variations in strength have no effect on the straightness of the rail or on form defects deforming the structure. The stock 1 and the guiding part 2 of the rail may differ from each other in thickness because the welding method does not involve geometric requirements as the rolling method does. Therefore, the guide rail can be designed considering both the required unit rigidity and the shaft space efficiency of the elevator. If the guide rail is assembled by welding, its stock 1 can be designed in a different manner than at present. The cross-section can be dimensioned according to the bending moment. In this way, the ratio of unit rigidity to mass can be further increased and possibly the distance between successive fail fixing points can be increased as well. Variable dimensions in the guide rail cross-section may be the width and thickness of the stock 1. Guide rails with a varying cross-section could allow increased intervals between rail fixing points e.g. in buildings with a steel framework, in which the placement of the rail fixtures is subject to stricter limitations and intermediate beams often have to be used. The number of rail fixtures also has an importance in situations where the elevator manufacturer supplies the steelwork for the shaft (installing an elevator in buildings without one, modernization and so-called home elevators) . In these cases, the rail fixing points in the shaft steelwork can be selected in ac- cordance with the interfloor distance. At present, the distance between rail fixtures depends on the flexural rigidity of the rail, which is constant because the rail has a constant cross-sectional form throughout the length of the rail both in the stock and in the guiding part. The distances between rail fixtures can be planned in accordance with the skeletal structures of the building.

Using laser welding with filler metal, rails of several profile sizes can be flexibly manufactured on the same production line. The cross-sectional form can be varied more freely than before. The component profiled parts of the guide rail are produced by roll forming or by using a conventional bending press. Bodies of a large thickness can be welded using the laser welding technique. The profiled parts are welded together in the lengthwise direction. During welding, extension plates joining the separate guide rail sections together are fixed to the guide rail. The dimensional tolerances are adjusted and the straightness is controlled by appropriate supply of filler metal and proper mounting of the parts. The narrow groove and low heat transfer that are possible in laser welding minimize the residual stresses of the welded guide rail, thus allowing straight rails to be produced.

A guide rail as illustrated by Fig. 1 is produced e.g. by the following process. Blanks of a length of max. 6 m are cut from a steel band e.g. by a mechanical method, by the flame cutting method or other thermic methods. The stock 1 is stiffened by means of a bending press. The welding is performed using a laser welding apparatus with a power of about 10 - 15 kW (C0₂ laser) and applying a filler metal wire to the melt. The parts under welding are so fastened that the rail dimensions are calibrated via application of filler metal and adjustment of the air gap, i.e. the welding clearance, which may be 0 when no filler metal is used or as large as desired when a filler metal is used. The filler metal used is generally steel. In single-run welding, the working speed may be of the order of 1.5 m/min in the case of 10-mm material thickness and 10-kW welding power. Laser welding requires only one run, which means the filler metal added during a welding operation. The filler metal is supplied into the melt in the form of a thin wire. In addition, the guiding surfaces and the guide rail joints are machined, the guide rails are straightened and the straightness is measured. The machining of the guiding surfaces can also be performed before the welding or the guiding surfaces can be made using a piece already machined.

Optimization of the welding parameters:

The dimensions have an effect above all on the capacity of the welding line and the welding parameters can be to some extent influenced via preparation of the groove. During safety gear action of the elevator, the strength of the weld is not a critical factor because the weld lies close to the neutral axis of the guide rail (bending about the x-axis) . Adjustment of the welding parameters must be possible regardless of material thickness in the guiding part of the guide rail, the choice of which is partly based on elevator regulations, availability and the clearances of car and counterweight guides available.

Control of welding:

During welding, the profiled parts of the guide rail are positioned by means of rollers or stop faces, with a posi- tioning accuracy of about 0.1 - 0.2 mm. The welding of the guide rails is performed by using rollers and stop faces to mechanically hold the guide rail parts in position during assembly and/or welding. A movable laser beam welds the lengthwise joint. If the groove has been preparared with sufficient accuracy, a filler metal need not necessarily be used.

Fig. 2a, 2b and 2c show alternative forms of the profiled guide rail. Fig. 2a presents a profiled guide rail made by bending from a single metal plate and welding the edges with an edge weld 4, in which part 2 is the guiding part and part 1 is the stock. In Fig. 2 there are two plate parts welded together using a fillet weld 5. In Fig. 2c, a weld is made in a pre-machined groove to improve accuracy, and these are welded with (two) fillet welds 6. The flexural rigidity of these profiled guide rails corresponds to the unit rigidity of the T-section rails currently used.

Fig. 3 presents a profiled guide rail with a machined facet or relief which allows a narrower weld to be made. This welded joint 7 is sufficiently strong as compared with a non-faceted joint and it can be welded faster due to its narrow width. The stock 1 of the guide rail has been stiffened by bending and the guiding part 2 is the machined part of the guide rail, acting as a slide surface or in contact with the roller guides and safety gear. The welding speed is independent of the thickness of the guiding part.

From Fig. 4 it can be seen that if the width of the stock 1 of the guide rail is increased, the flexural (horizontal) strength of the guide rail is not notably improved in the direction perpendicular to the guide rail but that it is greatly improved in the direction of the stock 1. Parts 8 of the guide rail stock are shaped in accordance with the local rigidity requirements while its middle area 9 is dimensioned to meet the maximum rigidity requirements. In a load-carrying guide rail, maximum stress occurs in areas remote from the fixing points. The fixing points are given by the constructor and the guide rail is designed accordingly to obtain an appropriate rigidity. Fig. a) shows a guide rail in side view and Fig. b) a guide rail as seen from the front side of the guiding part.

Fig. 5 illustrates the welding of the guide rail and the manner of holding the guide rail parts in position during welding. The stock 1 is held on the bench 13 by means of welding clamps 12 while the guiding part 2 is held in place by means of a transfer gear 10. The laser beam itself is moved by means of a transporter 19. Laser welding of the stock 1 and the guiding part 2 is carried out by directing the laser beam and supplying the filler metal through the laser beam transporter 19 and its tip 14 to the point 11 under welding.

Fig. 6 presents a laser welding apparatus in which the beam transport is implemented using a portal robot 18. In Fig. 6, one guide rail is being welded while another guide rail is being prepared for welding. From a laser beam generator 17, the beam is passed via part 15 and an optical lens and mirror system to the object under welding by means of a laser beam transporter 19. The welding robot is mounted on a base 18 on which the robot and the laser beam transporter 19 driven by it are moved. The pillar-like parts 29 form the portal of the robot in which the laser beam transporter 19 moves, and the pillar-like parts 29 move on the fixed base 18 of the welding robot.

The movable part 30 of the portal is moved on the fixed pillar-like parts 29 and the base 18 of the welding robot, onto which the welding bench 13 with the clamps is brought. The welded guide rail is removed from the welding robot by means of a rail conveyor 16. Parts 15, 17, 29 30 and 19 constitute the welding robot and parts 16, 12 and 10 are devices needed for holding the object in position.

Fig. 7 illustrates the stages of manufacture of guide rails. On production line I, number 20 indicates a storage for steel plates. Number 21 indicates a plate taken out of the storage, and the plate is cut by a plate shearing machine 22 and bent by a bending press 22. Next, the prepared parts 24 are taken into the welding machine 18 by a conveyor 25. Corresponding operations are carried out on a second component line II producing guiding parts 2. The welded guide rail is moved by a second conveyor 26 to an interim storage 27, whereupon the ends and guiding surfaces of the guide rails are machined on a grinding machine 28. Via laser-welding implemented in the manner illustrated by Fig. 5, 6 and 7, the straightness required by elevator guide rails can be achieved.

It is obvious to a person skilled in the art that the invention is not restricted to the examples described above, but that it may instead be varied within the scope defined by the claims.

Claims

1. Procedure for the manufacture of an elevator guide rail, said guide rail consisting of a stock (1) and a guiding part (2) , characterized in that the procedure comprises at least the follwing operations:

- the cross-section of the profiled guide rail is dimen¬ sioned in accordance with the bending moment of the guide rail and the dimensions of the elevator shaft and interfloor distance of the building and the thicknesses of the stock (1) and guiding part (2) are selected independently of each other

- the stock (1) is stiffened.

2. Procedure as defined in claim 1 for the manufacture of guide rails, characterized in that the stock (1) and the guiding part (2) are welded together by means of a laser beam.

3. Procedure as defined in claim 2 for the manufacture of guide rails, characterized in that the dimensional toler¬ ances and straightness of the guide rail are adjusted via supply of filler metal and mounting of the parts of the guide rail.

4. Procedure as defined in claim 3 for the manufacture of guide rails, characterized in that during the assembly and/or welding of the profiled guide rails the parts are held mechanically in position using rollers and stop faces.

5. Procedure as defined in claim 4 for the manufacture of guide rails, characterized in that the dimensions of the guide rail are calibrated via supply of filler metal and adjustment of the air gap.

6. Procedure as defined in claim 2 for the manufacture of guide rails, characterized in that, if necessary, the guide rail is stiffened by welding the stock (1) of the guide rail from a thicker plate or by stiffening the stock by using a bent plate.

7. Procedure as defined in any one of the preceding claims for the manufacture of guide rails, characterized in that the profiled guide rail is provided with a machined facet, relief or a narrower welding joint.