EP2331272B1

EP2331272B1 - Production line for lift guides and similar products and productive process for making thereof

Info

Publication number: EP2331272B1
Application number: EP09760293.2A
Authority: EP
Inventors: Tiziano Granata
Original assignee: Monteferro SpA
Current assignee: Monteferro SpA
Priority date: 2008-08-25
Filing date: 2009-10-23
Publication date: 2022-01-12
Anticipated expiration: 2029-10-23
Also published as: EP2331272A2; WO2010023563A2; WO2010023563A3

Description

The present invention relates to a production line for making lift guides and similar products, as well as to a productive process carried out by this production line, and the lift guides obtained through this process.
It is known that lifts and the like during running move along suitable rectilinear guides defining the lift path; generally, these guides are defined by metal bars that are some meters long and are mounted in succession during installation of the lift so as to define the rectilinear path followed by the latter.
The above mentioned guides generally have a section in the shape of an inverted "T" wherein a protruding element centrally emerges from a base, which element will define the so-called "runway" along which the lift moves.
It is apparent that the geometry of the runway directly and significantly affects the lift performances in particular as to the running comfort; therefore, accomplishment of guides for lifts as much as possible complying with the quality standards is of fundamental importance (obviously in addition to a correct installation of the guides during the lift-mounting step) to enable the qualitative specifications to be maintained to a high level, above all in terms of vibrations transmitted to the persons occupying the lift car.
Known in the production field (and also through documents) are different production lines for lift guides, a possibility of implementation of which is known from Spanish patent Nos. ES405334 and ES405335 (now expired).
In particular, the process described in these documents starts from the hot-rolled profile of the guide and performs a series of steps in which the profile is straightened, the guide head is worked and finished and finally the longitudinal ends of the guides are worked so as to make couplings between the end of one guide and the end of the following guide.
In detail the above mentioned Spanish documents describe three different straightening processes, which can be carried out manually, by means or rolls or "by deformation"; in the last mentioned system a machine tool is used which is equipped with a fixed head and a movable head operating on the guide and suitably deforming it beyond its limit of elasticity; in addition, the pressure side of the deformation heads on the guide is inverted so as to correct deformations of the guide in both ways.
By the last-mentioned step an accurate straightening is ensured and defects of perpendicularity and bending are eliminated along the longitudinal axis, and subsequently the profile head is machined by use of a plane acting by subsequent passages with a suitable tool; this step allows a profile head to be obtained which has surfaces conditioned to optimal sliding.
The last operation concerns working of the ends so as to produce interlocking couplings of different types (for instance, plain couplings or couplings by means of a junction plate provided with holes for engagement of the plates, and so on).
The general steps and the machine tools described in the prior-art Spanish documents mentioned above appear to be susceptible of improvements under different points of view, and in particular as regards the requirements of working accuracy, and optimisation of work timing (leading to the need for continuous improvements in the different production steps).
Other production lines for lift guides are known from patent applications EP1214990A2 ,which forms the basis for the preamble of claims 1 and 5, and DE102005027640A1 .
Accordingly, the present invention aims at meeting the requirements highlighted above, and in particular it is an aim of the present patent to make available a production line for lift guides enabling straightening of the guide to be optimised, and twisting problems to be eliminated, while at the same time optimising the work timing and broaching operations.
Another aim of the invention is to make available a production line for lift guides utilising a planing machine (and the related planing step) capable of optimising the working speed without this being to the detriment of accuracy.
It is a further aim of the invention to make available a production line for lift guides and a production process (and the guide obtained from such a process) that are optimised in terms of costs, performances and accuracy, so as to enable a production of optimal manufacture and competitive costs to be obtained.
The foregoing and further aims that will become more apparent in the course of the following description are achieved by a production line for lift
guides and similar products according to the features of claim 5, a productive process for lift guides or similar products according to the features of claim 1.
Further features and advantages will become more apparent from the detailed description of preferred but not exclusive embodiments of production lines for lift guides and similar products in accordance with the invention.
The invention will be hereinafter described with reference to the accompanying drawings, given by way of non-limiting example, in which:

Fig. 1 shows a production line for lift guides and similar products, referred to as "drawing line";
Fig. 2 diagrammatically shows a production line for lift guides and similar products in relation to a second embodiment referred to as "planing line";
Figs. 3 and 3a are perspective views of a guide for lifts and coupling of two guides in succession respectively, which can be obtained by the production lines for lift guides in accordance with Fig. 1 or 2;
Fig. 4 diagrammatically shows a straightening apparatus used in the drawing line and planing line of Figs. 1 and 2;
Figs. 4a and 4b show a possible operation of the apparatus seen in Fig. 4 along two different lying planes of the guide;
Fig. 4c shows a detail concerning operation of the machine in Fig. 4; and
Fig. 5 shows a drawing apparatus to be used in the method of the present invention.

With reference to the drawings, a production line for lift guides and similar products in accordance with the present invention has been generally identified with reference numeral 1.
In particular, the production lines hereinafter described are adapted to make guides 2 of the standard type, for instance in accordance with UNI 7465:1997 (E) specifications and subsequent ones, each having a base 3 and a portion 4 emerging from such a base.
Looking at Fig. 3 it is possible to see that the section in a plane normal to the extension axis "L" of the guides substantially has the shape of an inverted "T" where the emerging portion 4 consists of the neck of guide 4a (a raw and generally unworked surface) directly supporting the runway 4b of the guide itself.
As it is still possible to see in the figures, normal male- female couplings 5, 6 are present, exactly at the emerging portions 4 at the opposite ends of each guide (Fig. 3a).
These male- female couplings 5, 6 aim at enabling alignment of the guide ends during the mounting and assembling steps of same.
Also provided for engagement between subsequent guides is a connecting plate 7 in engagement at the lower part thereof with the base 3 of said guides 2; in particular, the connecting plate 7 is longitudinally interposed between two guides in succession.
For the purpose of engaging the connecting plate 7 to the ends of guides in succession, formation of suitable holes 8 is provided in each final end of the guide and at each side of base 3 (see Fig. 3a again).
Now, through examination of the production line for guides seen in Fig. 1, it is possible to conveniently notice the following.
In a first embodiment of the method underlying the present invention, the raw guides 2 (made following quite known technologies and usually having a varying length included between 4 and 10 meters) are brought onto the loading bench of a first sandblasting machine 100, generally in homogeneous groups and with amounts depending on the type of profile to be worked.
The sandblasting machine 100 is equipped with suitable means for removal of the surface oxides and the calamine from the rolled profile; in particular, the sandblasting operation carried out by said removal means takes place using a suitable mixture of metal abrasive and sand.
When the sandblasting operation has been completed, by use of a suitable translator, of the automatic type for example, guides 2 are brought to a drawbench or drawing machine 200 where they are appropriately inserted in a modular box (to be also defined as "drawing box") consisting of a holding body 50 and a given number of modular elements 60 to be housed in the holding body 50 and adapted to define a corresponding plurality of drawing sections depending on the type of profile to be worked.
In more detail, it is possible to see that the modular elements 60 are mutually interchangeable and are preferably identical with each other in terms of sizes and general proportions; in this way production and management costs for the drawing box can be greatly reduced.
Definition of the drawing profile within the holding body 50 is then carried out by suitably positioning the modular elements 60 intended for lift profiles.
Said modular box, shown in Fig. 5, is further equipped with adjusting systems designed to enable adaptation of same to the tolerances of the rolled product and also designed to give the guide final sizes, in compliance with the dimensional and geometrical tolerances required.
By a further transfer system, for instance by motor-driven chains, the guides are transferred from the drawing machine 200 (or drawing station) to a first straightening unit (or station) 300, typically a roller straightening machine; the rollers of this machine can be adjusted both in height and in inclination so as to enable a substantially rectilinear guide with reduced twisting to be obtained.
In addition, the straightening unit 300 is adapted to control the perpendicularity between base 3 and runway 4b through suitable size detection or reading sensors.
Through utilisation of a series of motor-driven roller beds, guides 2 are then brought to an automatic cutting unit 400 which carries out cutting of the guides into suitable stretches (that generally vary in length from 0.5 m to 6.5 m), in a direction transverse to their longitudinal extension direction "L"; at this point, guides 2 cut to the desired size are transferred, by further motor-driven roller beds, to a twisting apparatus 500.
During working in this twisting apparatus 500, a suitable correction twisting torque is applied, as a function of the deformations and/or rotations developing around the longitudinal axis "L" of the guide 2 being worked (these deformations and/or rotations are submitted to due reading through suitable sensor means); should the current requirements call for it, after applying this correction twisting torque, guide 2 is again checked (by a new reading) and, if necessary, a new correction is applied by further twisting between the two heads.
At this point guides 2 (or also only a single guide 2 being worked) are/is brought close to an apparatus 600 for carrying out straightening (which operation can take place in an automatic manner); this apparatus 600 meets the requirement according to which each guide 2 must be perfectly rectilinear (or, in other words, the requirement according to which each guide 2 must remain within the tolerance limits established by the reference regulations or the specifications relating to the plant) with reference to its longitudinal extension axis and with reference to the lying plane 21 passing through the emerging portion 4, and also with reference to the lying plane 22 passing through the base 3 (see Figs. 3, 4a and 4b).
Apparatus 600 therefore aims at ensuring the straightness of the two lying planes and is diagrammatically shown in Figs. 4, 4a and 4b; in these figures it is possible first of all to see a supporting frame 9 adapted to support at least one guide 2 to be straightened.
As shown in Fig. 4, at least two lateral reading units 10, 11 are also present, as well as a central work unit 12, said units being longitudinally spaced apart from each other along the extension direction "L" of the guide.
In particular, these distances (denoted with letter "l" in the figure) can be varying distances adjustable a priori, as a function of the number of straightening operations that are intended to be performed and the final accuracy or precision that is wished to be obtained as regards the alignment condition of the guide itself; in any case, within the scope of the present invention, it is also possible that these distances (between unit 10 and unit 11 and between unit 11 and unit 12) be different from each other, in which case they generate a longitudinally non-symmetric configuration.
In greater detail, it is possible to see that the reading units 10, 11 act at respective areas 13a, 13c of the guide (which areas vary during the straightening steps due to the relative movement between them and the guide, as better clarified in the following); vice versa, the work unit 12 acts at an area 13b of the same guide interposed along the longitudinal extension direction L between said areas 13a, 13c.
The reading units 10, 12 first of all perform a function of acquiring a respective position P, P" of the respective area 13a and 13c; in other words, the reading units 10, 12 through suitable sensors, optical sensors for example, read the position by points P, P" of the real longitudinal extension axis 20 of the guide.
It is in fact to be pointed out that the aim of apparatus 600 is exactly that of making the real axis 20 of the guide coincide with a perfectly-rectilinear ideal longitudinal extension axis L; in this regard, looking at Fig. 4c (in which the deviations from the straight line have been greatly increased to highlight operation of the machine), it is possible to see that the real axis 20 of the guide has irregularities or bends deviating it from the required linearity, this at least with reference to the two lying planes mentioned above.
The straightening apparatus therefore aims at obtaining said straightness, in particular through working by points on areas 13b of the guide in succession along the work feeding axis (coincident with the longitudinal extension axis "L" of the guide 2 being worked).
Still with reference to Fig. 4c, it will be also recognised that apparatus 600 also aims at causing points P' subsequently analysed to become coincident (if they are not yet coincident) with the respective "ideal" points P_ID defined on the ideal extension axis "L" (which in turn can be considered as the "ideal" extension axis of guide 2, if the latter is already perfectly formed and uniformly rectilinear).
Therefore, after identifying positions P and P", a work unit 12 acts on the guide at the grip area 13b for applying by points on the guide itself, a force F on axis L so as to deform the guide beyond the point of elasticity, leading it as much as possible to take the required straightness in the intervention region.
In other words, the work unit 12 will take an inverted-"C" configuration, and will engage an upper region of the guide that can be, as a function of the guide position on the machine, the runway 4b (see Fig. 4a) or a side of base 3 (see Fig. 4b).
Force F can be applied by a pulling or pushing action, so as to enable correction of position deviations from the axis of points that are in either of the halfplanes defined by said axis L (Fig. 4); in order to implement these functions, the work unit can be configured between a moved-apart position at which it does not act on the guide and a relative movement is possible between units 10, 11, 12 and guide 2, and a plurality of work positions at which on the contrary the C-shaped engagement portion is rigidly secured to the guide.
The above mentioned plurality of work positions corresponds, case by case, to the different deformations that the work unit can impose to the guide in a direction transverse to the axis; it is in fact to be noted that for bringing an area 13b to a straightness condition it is generally required that a point P' be brought towards and then beyond point P'_ID in order to take into account springing-back of the guide (so that under a situation in the absence of forces, points P' and P'_ID will be coincident).
In other words, intervention of the machine 600 takes place in such a manner as to cause displacement of areas 13a, 13b, 13c relative to each other along a direction transverse to axis L so that, taking into account springing-back of the guide material, if the deformation force F is removed, points P, P' and P" corresponding to the mentioned areas will be as much as possible in alignment with each other along the ideal axis L, i.e. will be coincident with points P_ID, P'_ID, P"_ID, respectively.
In accordance with an operating mode of the present method, the apparatus starts working from one end of guide 2 (condition shown in Fig. 4) and intervenes by discrete steps in succession (adjustable a priori depending on requirements) in a plurality of longitudinally successive points of guide 2 until reaching the other end of the guide 2 itself.
It is also to be pointed out that the lateral reading units 10, 11 are movable between a position moved apart from guide 2 (to enable said relative motion with the guide, i.e. to enable them to come close to the following reading/intervention point) and a work position at which they are substantially integral with the respective lateral grip area 13a, 13c on the guide; in other words, the reading units are made integral and keep fastened to the guide and to frame 9 during the deformation intervention step of the work unit 12.
Apparatus 600 for guide straightening further comprises a control unit 14 adapted to receive, as an input, deformation reading signals of the reading units 10, 11 and/or the work unit 12, i.e. the position data (or to be able to obtain the position) of points P, P', P"; the control unit therefore determines a suitable command signal 18 to be sent to the work unit 12 to establish the work position thereof and in particular to determine the deformation condition imposed to the guide for displacement of the grip area 13b relative to the lateral grip areas 13a, 13c (so as to apply the appropriate deformation force F on the guide and obtain the desired deformation).
Once intervention has been completed, a new reading of positions P, P' and P" by the three units 10, 11, 12 is carried out in order to check whether the straightening operation in the concerned area has been successful and, if the operation has not been successful (or reading would still show linearity errors beyond the established tolerances), apparatus 600 will intervene once more following the same modalities.
In this connection, apparatus 600 for guide straightening further comprises a correction module 19 adapted to determine a correction factor of the theoretical work position corresponding to the theoretical deformation condition to be imposed to the guide for displacement of the central grip area 13b giving rise to the condition of substantial longitudinal alignment.
The correction unit acts both in the horizontal and in the transverse directions increasing the execution quickness based on the parameters relating to the material strength resulting from the data reproduced on the casting certificates entered by the operator in the machine software in an appropriate periodical manner.
It is however apparent that, in spite of how accurate and precise the computing systems are, there will always be variables coming into play which cannot be taken into account by the apparatus 600 and are connected to the real behaviour of the material that is not always perfectly homogeneous for example, as it can show small geometric or structural defects on the guide; in this manner it is apparent that sometimes the deformation (i.e. the force F) to be applied for obtaining the optimal result will be different from the calculated theoretical one.
The correction module 19 will generally be a software module that will intervene and correct the work position that unit 12 has to take for correcting the straightness defects as a function of the real deformation occurred and read during the working step on the areas 13b preceding the guide 2; therefore, by checking the real behaviour of the material in preceding situations, it is possible to foresee the material behaviour in following intervention regions in a more precise manner.
By operating in such a manner, the number of interventions on the guide can be reduced, while at the same time the production speed can be increased and the stressing action on the guide reduced.
In order to further increase the work accuracy, the central work unit 12 reads the respective position P' of the related area 13b with a greater precision tolerance than reading of the respective position P, P'' of the areas 13a, 13c carried out by the two reading units 10, 11; the guides 2 thus worked are then brought close to a corner-removing machine 1100 which, by a series of tools eliminates the upper corner of the runway 4b of the guide.
After being worked in the machine 600, the guide 2 can be conveniently submitted to additional working operations to be carried out sequentially, such as finish operations (a broaching operation for example, to be carried out in a suitable broaching machine 700, or a brushing operation to be carried out in a brushing machine 800) and/or completion operations (such as arrangement of holes 8 to be carried out by a punching machine 900 suitably dedicated to this purpose).
In more detail, the guide being worked is transferred to a finish line (or sub-station) comprising at least one broaching machine (simultaneously machining both ends of the guide), one or more brushing machines (the function of which is to remove burrs from guide 2 being worked), one or more presses or machines adapted to carry out holes and finally a so-called "surfacer".
Still for the purpose of obtaining a suitable finish degree, in the corner-removing machine it is possible by a series of tools, to remove the upper corner of the runway of the guide being worked.
Conveniently, before the corner-removing operation it may provided that according to the present invention the finish operation be carried out (or more particularly, the so-called broaching operation).
Subsequently, the guide 2 being worked is brought to a packaging unit 1300 where the same is substantially packed for subsequent steps of storage and transport.
According to a second embodiment of the process underlying the present invention, it is possible to provide that at the beginning of the operating cycle one or more raw guides 2 (that possibly have been previously sandblasted and/or coated with a suitable primer) are loaded on a twisting station 2000 where suitable sorting means (an automatic singling device, for example) enables the production/machining line to be fed.
This twisting station 2000 carries out "reading" of each guide 2, measuring the twist between the two heads by a sensor system; after this reading, one or more pairs of movable vices clamp the two guide heads and a twisting torque is applied to at least one of these heads in order to correct twisting and bring the guide within the parameters imposed by the reference regulations.
After the correction twisting torque has been applied, the guide is again submitted to "reading" of its size parameters and, if necessary, a new correction is applied.
Then the guides enter the automatic straightening station 3000 which, acting with a discrete pitch (varying as a function of the guide type) carries out straightening of the bar in both lying planes.
This machine is equipped with three reading heads adjustable in terms of pitch, two of which are fixed and one movable, and by applying a suitable force to the movable head, correction of the local deformation of the guide is carried out.
A suitable software corrects the theoretical force, based on measurements occurred during the working steps in order to reduce the straightening steps.
After the correction force has been applied, the guide becomes the subject of a new "reading" and, if necessary, a new correction is applied.
The guides are then transferred to an accumulation region, where a portal handling device picks them up and positions them on the work surface (that advantageously can be a magnetic one) of a planing machine 4000; this machine performs a two-way planing operation on the guide 2 being worked, using a series of tools that can simultaneously machine the whole band constituting the runway of guide 2 (inclusive of the upper part thereof).
According to a feature of the present method, the planing machine 400 is adapted to carry out all necessary machining operations on a guide 2 being worked in a single "full" run or stroke (i.e. by a single forward movement followed by a single backward movement along the extension axis of the guide and sequentially in time relative to the mentioned direct stroke) along the extension axis of guide 2.
From a structural point of view, the planing machine 4000 comprises a work head including a monoblock element on which a tool-holding support can be mounted (which tool-holder in turn supports and keeps a plurality of roughing and/or finishing tools to the appropriate operating position); in addition, the head comprises a roughing module and a finishing module alternately operating on guide 2, which can be conveniently configured in a work position (where they bring the respective tools into contact with guide 2 for carrying out the respective machining operations for at least one stroke) and in a rest position (where, on the contrary, the move the respective tools away from guide 2).
Referring in particular to the above illustrated possibility, it is possible to see (by way of non-limiting example) that the work head of the planing machine 4000 can comprise a substantially fixed roughing module, while the finishing module (placed adjacent to the roughing module) can be reversibly configured between the aforesaid "work" and "rest" positions.
Advantageous, all the operations hitherto described can be performed without the aid of cooling fluid; this operating possibility can be achieved by a suitable gauging of the cutting/intervention angles of the tools on the guide being worked and/or an appropriate selection of the material of which the tools are made (for instance, using tools made of a hard metal alloy or the like).
At the end of planing the guides are brought by roller beds (or transport devices of equivalent operation) to the twisting line 5000 that can be interlocked with an automating singling device.
In the twisting line 5000 a new "reading" of each guide 2 being worked is carried out, the torsional stress between the two heads being measured by a sensor system; depending on the values detected from such a reading, a pair of movable vices is operated, which vices clamp the two heads of the guide 2.
A twisting torque is applied to one of the two vices, in order to correct the twist and bring the guide 2 within the parameters imposed by the reference regulations.
After the correction twisting torque has been applied the guide is "read" again an, if necessary, a new correction is applied.
Then the guides enter the automatic straightening line 6000 which, by acting with a discrete pitch (varying as a function of the type of guide) carries out straightening of the bar in both lying planes; this machine is provided with three reading heads adjustable in the pitch, two of which are fixed and one movable, and acts by applying a suitable force to the movable head (so as to correct possible local deformations of the guide 2 being processed).
In the last-mentioned work station too a suitable software corrects the theoretical force based on the measurements occurred during the working step in order to reduce the straightening steps.
After application of the correction force, the guide is read again and, if necessary, a new correction is applied.
Through a transfer chain, guides 2 reach a grinding station 7000 where a belt grinder gives the desired roughness to the surface of the runway.
The smoothed bars are transferred to a finish station 8000 that is conveniently structured into several sequential sub-stations and comprises at least one broaching machine (simultaneously machining both ends of guide 2), one or more brushing machines (intended for removal of burrs from guide 2) and one or more presses (for punching operations) and finally one or more flattening machines for the guide base (also referred to as "sole" in this particular field) and at least one surfacer 9000.
As already seen for the other embodiment previously illustrated, in this case too the presses are equipped with suitable dies with inclined shoulders that are able to simultaneously form the four fastening holes 8 of guide 2; at the same time, the sole flattening machines are equipped with a system enabling the parallelism tolerances of the flattened region with the runway to be observed.
The following work station 10000 is adapted to carry out a control of the straightness of the guides; this control can be implemented by a system of laser pointers for example, determining the maximum camber of the guide relative to an absolute reference.
The guides are subsequently brought to an application station for applying a protective coating 11000 and a subsequent packaging station 12000.
Should the current requirements call for it, it is also possible to implement a "hybrid" form of the present production method, in which guides 2 having been submitted to machining operations in stations 8000 and/or 9000 (i.e. the guides that have been submitted to different finish and/or surfacing operations) can be transferred to special machining stations 1400 shown in the first embodiment of the invention; in this way suitable new machining operations can be obtained by cutting, drilling, flattening and accomplishment of interlocked couplings for obtaining stretches of varying length and/or with special holes.
The invention achieves important advantages.
First of all the guide production line for lifts in accordance with the invention allows the precision and tolerance of the outgoing guides to be improved ensuring an optimal qualitative control without substantially increasing the production costs.
The apparatus for straightening the guides appears to be very precise and functional and also acts in such a manner as to reduce to a minimum the number of automatic operations required for obtained the desired tolerance.
By adopting a broaching machine capable of simultaneously machining both ends of a guide, the working time is greatly reduced as well as the number of machines necessary for carrying out such operations as compared with standard lines.
Since the device for planing the guide acts in a single passage, the working time is greatly reduced and, as a result, also the overall costs of the guide are reduced.
In addition, the process is fully automatic and does not require additional cooling liquids to be provided, which liquids increase the running and servicing costs.
Due to the presence of control stations for checking the different machining operations, the possibility of errors is reduced and, as a result, costs for returned goods and storage of same are avoided.

Claims

A process for producing guides for lifts or similar products, comprising the following steps:
- providing a raw guide;

- preferably applying a torsional stress to the guide for removing a twist by a twisting apparatus (500);

- carrying out at least one straightening operation by a straightening apparatus (600);

- carrying out finish operations on the guide (2);
the straightening operation comprises the following sub-steps:

- supporting said guide (2) by a supporting frame (9);

- providing at least two reading units (10, 11) acting on respective lateral grip areas (13a, 13c) of the guide (2);

- providing at least one work unit (12) presenting an inverted-"C" configuration and acting on a central grip area (13b) of the guide (2), said work unit (12) being configured to engage an upper region of the guide (2) to apply a force (F) on the guide (2) by a pulling or pushing action, the reading units (10) (11) being disposed laterally of the work unit (12) placed in the middle along an ideal extension axis (L) of the guide (2) ;

- reading, through the reading units (10, 11) and through the working unit (12), respective positions (P, P', P") of the lateral grip areas (13a, 13c) and of the central grip area (13b) relative to the ideal longitudinal extension axis (L) of the guide (2);

- determining, by a control unit (14), an appropriate command signal (18) to be sent to the work unit (12) for establishing the work position and in particular the deformation condition imposed to the guide for displacement of the grip area (13b) relative to the lateral grip areas (13a, 13c)
, according to said reading of respective positions (P, P', P");

- applying a force (F) transverse to the ideal longitudinal extension axis (L) by said work unit (12) according to said command signal (18), the transverse force (F) being applied in the position (P') of the central grip area (13b), the transverse force (F) being a function at least of the operation of reading the positions (P, P', P") of the lateral grip areas (13a, 13c) and the position (P') of the central grip area (13b) to bring a real longitudinal extension (20) of the guide to a condition of substantial alignment with the ideal longitudinal extension axis (L); characterised in that it comprises also the step of determining, by a correction module (19), a correction factor of the theoretical work position corresponding to the theoretical deformation condition to be imposed to the guide (2) for displacement of the central grip area (13b) and the condition of substantial longitudinal alignment,
said determination of the correction factor of the theoretical work position and said determination of the condition of substantial longitudinal alignment being carried out preferably by a software module and correcting the work position as a function of the real deformation occurred and read during the working step on the preceding central grip areas (13b) of the guide (2) itself.
A process as claimed in claim 1, characterised in that it further comprises a step of reading, through the work unit (12), a position (P') of the central grip area (13b) relative to the ideal extension axis (L).
A process as claimed in claim 2, characterised in that it further comprises the step of determining, through a control unit (14), a transverse force (F) to be applied for bringing the position (P') read by the work unit (12) and/or calculated as a function of the positions (P) and (P") read by the reading units (10, (11), substantially close to the ideal position (P'_ID) placed on the ideal longitudinal extension axis (L).
A process as claimed in claim 3, characterised in that it further comprises the step of correcting the transverse force (F) calculated as a function of the response under deformation of the guide (2) obtained in a preceding step in response to application of a respective transverse force (F) to the guide itself.
A production line for lift guides and similar products, comprising an apparatus for straightening guides (600), having:
- a supporting frame (9) adapted to support at least one guide (2) to be straightened;

- at least two lateral reading units (10, 11) and a central work unit (12) longitudinally spaced apart from each other for acting close to at least three longitudinally spaced apart distinct areas (13a, 13b, 13c) of a guide (2),
- the lateral reading units (10, 11) reading a respective position of the respective lateral grip areas (13a, 13c) relative to an alignment condition,

- the central work unit (12) being movable between a position moved apart from the guide and a plurality of work positions at which it is integral with the central grip area (13b) on the guide, said plurality of work positions corresponding to conditions of deformation as imposed to the guide for displacement of the central grip area (13b) relative to the side areas (13a, 13c) preferably for recreating, in the absence of an imposed deformation, a condition of substantial longitudinal alignment of the areas (13a, 13b, 13c) of the guide (2),

- the lateral reading units (10), (11) are movable between a position spaced apart from the guide (2) and a work position at which they are substantially integral with the respective lateral grip area (13a, 13c) on the guide; and

- the lateral reading units (10), (11) and the central work unit (12) are movable relative to the guide (2) along its extension axis (20), preferably with a discrete pitch, to enable reading of positions (P, P'') in a plurality of distinct lateral grip areas (13a, 13b) of the guide, the central work unit (12) being movable between the spaced apart position and the plurality of work positions for re-establishing a substantial alignment condition of the guide in each of said different relative positions (P'), said central work unit (12) presenting an inverted-"C" configuration and being configured to engage an upper region of the guide (2) to apply a force (F) on the guide (2) by a pulling or pushing action;
said straightening apparatus (600) also comprising:

- a control unit (14) adapted to receive, as an input, deformation-reading signals (15, 16, 17) of the lateral reading units (10, 11) and/or the central work unit (12), the control unit determining an appropriate command signal (18) to be sent to the central work unit (12) for establishing the work position and in particular the deformation condition imposed to the guide for displacement of the central grip area (13b) relative to the lateral grip areas (13a, 13c) , so as to apply a suitable deformation force (F) on the guide (2) ;
said straightening apparatus (600) being characterised in that it comprises also a correction module (19) adapted to determine a correction factor of the theoretical work position corresponding to the theoretical deformation condition to be imposed to the guide (2) for displacement of the central grip area (13b) and determine the condition of substantial longitudinal alignment, said correction module (19) being preferably a software module and correcting the work position as a function of the real deformation occurred and read during the working step on the preceding central grip areas (13b) of the guide (2) itself.
A line as claimed in claim 5, characterised in that the lateral reading units (10), (11) and the central work unit (12) act on the guide (2) along a first lying plane (21) for establishing a condition of substantial alignment of the emerging portion (4) of the guide (2) along the longitudinal extension direction (L).
A line as claimed in claims 5 or 6, characterised in that the lateral reading units (10, 11) and the central work unit (12) act on the areas (13a, 13b, 13c) of the guide (2) along a second lying plane (22) for establishing a condition of substantial alignment of the base (3) along the longitudinal extension direction (L) .
A line as claimed in anyone of the preceding claims from 5 to 7, characterised in that the central work unit (12) reads a respective position (P') of the related area (13b) relative to a longitudinal alignment condition (L) of the guide (2).
A line as claimed in anyone of the preceding claims from 5 to 8, characterised in that the longitudinal distance (1) between a lateral reading unit (10) and the central work unit (12) is adjustable.
A line as claimed in anyone of the preceding claims from 5 to 9, characterised in that the central work unit (12) reads the respective position (P') of the related central grip area (13b) with a greater precision tolerance than reading of the respective position (P, P") of the lateral grip areas (13a, 13c) carried out by the two lateral reading units (10), (11) .
A line as claimed in anyone of the preceding claims from 5 to 10, characterised in that the lateral reading units (10, 11) and/or the central work unit (12) comprise a respective substantially C-shaped grip element suitable for engagement under operating conditions with the emerging portion (4) of the guide or with one of the lateral wings of the base (3).