Patent Publication Number: US-2023150005-A1

Title: Machine and method for the working of tubes

Description:
FIELD OF THE INVENTION 
     The present invention concerns a machine for working tubes, in particular a hairpin bender machine for bending tubes intended, in particular, for making heat exchangers. 
     BACKGROUND OF THE INVENTION 
     Finned heat exchangers are known, used in a wide variety of uses, such as small heat exchangers used in the automotive sector, or large heat exchangers used in machines for air conditioning or industrial refrigeration. 
     Heat exchangers generally consist of a finned pack passed through by one or more banks of overlapping tubes in which the heat exchange fluid circulates. 
     The tubes are connected in series, or in parallel, in their terminal parts, to create a circuit which typically provides to invert the flow by 180°. 
     For reasons of manufacturing convenience, that is, to eliminate brazing at least at one end of the tube, instead of mounting them in pairs in parallel with each other, the tubes are bent in a U shape with the arms parallel, to produce the so-called hairpins. 
     The hairpins are commonly produced with hairpin bender machines, which comprise at least means to feed the tubes to be worked and a bending unit suitable to bend the tubes by a desired angle. 
     One disadvantage of known hairpin bender machines is that they are not able to make hairpins longer than 4-5 meters. 
     Therefore, for larger finned packs, in which the length of the hairpins is not sufficient, straight tubes or segments of a greater length must be used, which are then connected to each other at 180° by unions or bends. 
     To allow the connection of the bends to the ends of the straight pipes, at least one of these ends must be subjected to a belling operation or process. The belling process creates a cup shape, that is, a flare, which allows to insert the small bend or unions inside it. 
     To make said segments, it is known to use specific tube cutting machines, which work one tube or more at a time, to straighten and cut the tube to the desired length and to make said flared end. 
     Therefore, in order to create straight tubes with a flared end and hairpins, it is necessary to use respective and different machines, each suitable to perform one process or the other. 
     Therefore, a production plant for tubes for heat exchangers of any size must be equipped with both tube cutting machines and also hairpin bender machines, which implies an investment both in terms of money and also in terms of considerable space. 
     There is therefore a need to perfect a machine for working tubes which can overcome at least one of the disadvantages of the state of the art. 
     In particular, one purpose of the present invention is to provide a machine for working tubes which allows to increase productivity while reducing the overall sizes compared with known machines of this type. 
     Another purpose of the present invention is to provide a flexible machine, that is, one which can be easily adaptable to the different work and production requirements. 
     The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages. 
     SUMMARY OF THE INVENTION 
     The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea. 
     In accordance with the above purposes, there is provided a machine for working tubes, in particular a hairpin bender machine, configured to simultaneously work a plurality of tubes intended to make heat exchangers. 
     The machine comprises:
         a feed and movement device configured to simultaneously feed and move a plurality of tubes to be worked,   a bending unit suitable to carry out bending operations on the plurality of tubes,   a cutting member configured to cut the plurality of tubes.       

     According to one aspect of the invention, the machine also comprises a belling device to perform, alternatively to a bending operation, a belling operation on at least part of the plurality of tubes. 
     In this way, a double-use hairpin bender machine is obtained which allows to alternate, according to requirements, either a work of bending the plurality of tubes in order to obtain a corresponding plurality of hairpins, or a belling operation in order to obtain, simultaneously, a plurality of straight belled tubes, that is, with at least one of their ends being flared. 
     Therefore, contrary to what is known, with the overall sizes and management costs of a single machine it is possible to produce two different types of tubes for heat exchangers, also on the basis of the length required. 
     Another advantage is that the possibility of working several tubes at the same time offers evident productivity advantages, especially as regards the belling workings which, with the state of the art, can be carried out only on individual tubes. 
     The invention also describes a method to bell a plurality of tubes with a hairpin bender machine, the method comprising:
         feeding a plurality of tubes to be worked on a plurality of feeding tracks defined by guides, and   moving the plurality of tubes toward a bending unit and a cutting member of the hairpin bender machine,   performing at least cutting operations on the plurality of tubes.       

     According to one aspect of the invention, the method also comprises:
         aligning with the tracks defined by guides for the tubes belling elements of a belling device, and   associating the plurality of tubes with the belling elements to perform a belling operation.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein: 
         FIG.  1    is a lateral view of a machine for working tubes in accordance with some embodiments described here; 
         FIG.  2    is a front view of a machine for working tubes in accordance with some embodiments described here; 
         FIGS.  3   a ,  3   b  and  3   c    are lateral section views along line III of  FIG.  2   ; 
         FIGS.  4   a  and  4   b    show two different steps of the belling operation; 
         FIG.  5    shows one end of a tube after the belling operation has been performed. 
     
    
    
     To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications. 
     DETAILED DESCRIPTION OF SOME EMBODIMENTS 
     We will now refer in detail to the possible embodiments of the invention, of which one or more examples are shown in the attached drawings. Each example is supplied as a non-limiting example of the invention. For example, one or more characteristics shown or described insomuch as they are part of one embodiment can be varied or adopted on, or in association with, other embodiments to produce another embodiment. It is understood that the present invention shall include all such possible modifications and variants. 
     With reference to  FIG.  1   , a machine  10  for working tubes is described, in particular, a hairpin bender machine for simultaneously working and bending a plurality of tubes intended, in particular, to make heat exchangers. 
     The machine  10  comprises a base  12 , such as for example a metal bearing structure, on which its main components at least partly rest and/or are installed, including:
         a device  14  for feeding and moving tubes to be worked,   a bending unit  16  suitable to carry out bending operations on the plurality of tubes,   a cutting member  18  configured to cut the plurality of tubes.       

     The tubes to be worked can be positioned in a feed magazine or slider, not shown, where they can be disposed, for example, in a plurality of coils able to be unwound. 
     The feed and movement device  14  can be configured to provide to unwind the coils and consequently to straighten the tubes for introduction into the machine  10 . 
     The feed and movement device  14  can comprise a plurality of guides  20  which define feed tracks which develop substantially parallel to each other and form a rectilinear path to guide the plurality of tubes up to the bending unit  16  ( FIGS.  3   a ,  3   b  and  3   c   ). 
     The feed and movement device  14  also comprises one or more engagement elements  17  configured to engage the plurality of tubes and to move them along the plurality of guides  20 . 
     The engagement elements  17  can also provide to remove the plurality of tubes from the machine  10 , for example after working, prior to cutting by means of the cutting member  18 . 
     In other variants of the machine  10  there can be extraction members, not shown, separated from the feed and movement device  14 , configured to remove the worked and cut tubes. 
     The removed tubes can be conveyed, substantially by gravity, onto movement members  19 , for example mechanical arms and/or conveyor belts, in order to be taken to a collection zone  23  where they are deposited in a container or suchlike. 
     The feed and movement device  14  comprises at least one drive motor. 
     The bending unit  16  comprises a bending arm  21  mounted on a support structure  22 , integral with the base  12 . 
     The bending arm  21  can be replaced based on the length of the tubes to be bent and/or the number of tubes to be bent simultaneously. 
     The bending arm  21  can be installed on a central support  26  mounted rotatable on the support structure  22 . 
     The bending arm  21  also comprises an operating surface  15  suitable to receive the plurality of tubes. The operating surface  15  can be provided with housings  27  for housing and retaining the tubes—also with suitable retention means—during the working operations. 
     The machine  10  also comprises a clamping unit, for example a group of clamps  24 , the seatings of which are configured to cooperate with the tracks defined by the guides  20  in order to jointly engage the tubes, keeping them in the correct position during the working operations, for example during bending. 
     The seatings that are formed by the association between the group of clamps  24  and the tracks defined by the guides  20  can have different diameters, allowing to work tubes of different diameters. 
     In correspondence with the clamps  24  there are bending shapes which contribute to form the bend of the plurality of tubes during the bending step. 
     According to some embodiments, the group of clamps  24  is positioned in correspondence with the central support  26 . 
     In order for it to move, that is, to rotate, the bending unit  16  is provided with at least one motor, for example a hydraulic motor, or an electric motor  28  advantageously of the brushless type. 
     The bending arm  21  can have at least two positions, a first starting position A and a second arrival position B. 
     In the first starting position A, the bending arm  21  is disposed with the operating surface  15  in substantial coplanarity with the guides  20 , in such a way as to take respective housings  27  into alignment with the tracks defined by the guides  20  in order to house and retain the tubes. 
     The bending can take place with a movement of the bending arm  21  complementary to the bending angle that is to be obtained on the plurality of tubes, or a portion thereof. 
     The bending on the plurality of tubes, or a portion thereof, takes place in correspondence with a working zone  25  which is substantially downstream of the group of clamps  24 . 
     A typical bend for tubes for heat exchangers consists of a bend of about 180°, corresponding to a movement of the bending arm  21  up to the second arrival position B in which the operating surface  15  is located above the tracks defined by the guides  20 , substantially parallel to them. 
     According to one aspect of the invention, the machine  10  also comprises a belling device  30  to perform, alternatively to a bending operation, a belling operation on at least part of the plurality of tubes. 
     According to the invention, in fact, the machine  10  can be configured to alternate one or the other working, even during the same operating step, that is, alternate the use of the bending arm  21  or the belling device  30 , for example according to the length of the tubes to be produced. 
     For shorter lengths, the machine  10  can be equipped to produce hairpins, as indicated above, while for longer lengths the machine  10  will be set to exclude the bending unit and to activate the belling device  30  in order to produce straight belled tubes, that is, flared at one of their ends ( FIG.  5   ). 
     With the same machine  10  it is therefore possible to carry out two different types of working, which can currently be achieved only by using different and separate machines. 
     The belling device  30  comprises belling elements  31 , each suitable to be aligned with each of the tubes in order to cooperate with one of its ends. 
     In particular, each belling element  31  is suitable to be aligned with each of the tracks defined by guides  20  of the feed and movement device  14 , in order to cooperate with one end of each tube of the plurality of tubes. 
     In accordance with some embodiments, the belling elements  31  can be disposed with a pattern which is complementary to the disposition of the tracks defined by guides  20 . 
     By means of this solution, the machine  10  is able to simultaneously carry out a belling operation of up to eight tubes having lengths for which the execution of hairpins is not possible or in any case not recommended. 
     In other variants, the machine  10  can be configured to bell a number even greater than eight tubes simultaneously. 
     With reference to  FIGS.  1  and  2   , the belling device  30  is positioned downstream of the tracks defined by the guides  20 , that is, in correspondence with the central support  26  onto which the bending arm  21  is mounted. 
     From  FIG.  2    it is also possible to appreciate the small sizes of the belling device  30 , which can be comprised inside the overall size of a conventional hairpin bender machine. 
     In this position, the belling device  30  can receive the end of the tubes at exit from the group of clamps  24  in order to work them while the group of clamps  24  keeps the plurality of tubes in position. 
     In other variants, the belling device  30  comprises its own group of clamps to retain the plurality of tubes during the belling work. 
     The belling device  30  can be attached on the base  12  or on the support structure  22 . 
     According to one variant, not shown, the belling device  30  can possibly be attached onto a support structure independent from the base  12  and/or from the support structure  22 . 
     However, in other variants of the machine  10 , the belling device  30  can also be mounted in other parts of the machine, either in a mobile or fixed manner. 
     In accordance with some embodiments, the belling device  30  can cooperate with translation members  34 , for example one or more sliders, which define a predetermined path on which the belling device  30  can move. Possibly, the one or more sliders  34  can be associated with a frame  32 . 
     In some embodiments, the belling device  30  can be associated with drive devices  36 , for example, an electric motor, which allow its movement. 
     The belling device  30  can also be associated with movement devices, for example one or more hydraulic or pneumatic cylinders  37 , or belts or toothed wheels, etc. which, driven by the electric motor  36 , allow it to be displaced. 
     With reference to  FIGS.  3   a  and  3   b   , the belling device  30  can be configured to move at least from an inactive position C in which the belling device  30  is positioned at a lower level than the tracks defined by guides  20  ( FIG.  3   a   ), to a working position D in which the belling elements  31  of the belling device  30  are aligned with the tracks defined by guides  20  ( FIG.  3   c   ), and vice versa. 
     In particular, in the working position D, each belling element  31  is coaxial to the tracks defined by the guides  20 . 
     According to one variant, the belling device  30  can comprise a movement member  29  for moving the belling elements  31  from an inactive position to a working position cooperating with one end of the tubes to be worked. 
     In order to perform the belling operation, the belling elements  31  are thrust by a movement member  29  and inserted into the end of the plurality of tubes in which the desired flaring is to be obtained. 
     During the belling operation, the plurality of tubes is advantageously engaged by the group of clamps  24 . 
     In  FIG.  4   a   , the belling device  30  is in the working position D with corresponding belling elements  31  coaxial to a plurality of tubes P located cantilevered with respect to the group of clamps  24 . In this case, the movement member  29  is retracted in a seating  35  thereof. The belling operation occurs by activating the movement member  29  which is made to move in the respective seating  35  causing each belling element  31  to be inserted into the end to be worked of each tube P of the plurality of tubes ( FIG.  4   b   ). 
       FIG.  5    shows what the end of a tube P worked by the belling device  30  described here looks like. 
     Advantageously, in the inactive position C, the belling device  30  can, for example, not interfere with other operations or workings, such as the bending ones. 
     In other embodiments, the working position D of the belling device  30  can also be provided with the bending arm  21  in the starting position A. 
     On the contrary, in the working position D the belling device  30  can be taken in correspondence with the working zone  25  in order to receive the plurality of tubes to be worked. 
     In fact, depending on the type of working chosen for the plurality of tubes, bending or belling, the machine  10  can be configured to alternate, respectively, the use of the bending arm  21  or of the belling device  30 . 
     According to some embodiments, a respective arrival position B of the bending arm  21  can correspond to a working position D of the belling device  30 . 
     Similarly, a respective starting position A of the bending arm  21  can correspond to an inactive position C of the belling device  30 . 
     In the arrival position B, the bending arm  21  is positioned in such a way as to free the access to the working zone  25  in order to allow the belling device  30  to be disposed in the working position D with respective belling elements  31  aligned with the tracks defined by the guides  20  on which the tubes are disposed in order to receive them. 
     In  FIGS.  1 ,  3     a  and  3   b , access to the working zone  25  is obtained by positioning the bending arm  21  at 90° with respect to the starting position A. 
     In other variants, access to the working zone  25  can also be obtained in other positions between the starting position A and the arrival position B of the bending arm  21 . 
     For example, the access can be obtained by moving the bending arm  21  with respect to the starting position A by 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105° and so on up to the arrival position B. 
     With reference to  FIG.  3   c   , the belling device  30  can also be positioned in a by-pass or discharge position E, which is between the inactive position C and the working position D. 
     The by-pass position E allows the belling device  30  to position, in axis with the tracks defined by the guides  20 , a sliding plane  33  in order to supply a guide and a support to the plurality of tubes during their movement toward the collection zone  23 . 
     The bending unit  16  and belling device  30  can be connected to a command and control unit, not shown, which manages the automatic or semi-automatic control of the various operating phases of the machine, for example, by commanding and controlling the motors  28  and  36  as well as the movement member  29 . 
     The command and control unit can be programmed to control and manage the alternate positioning of the positions A-C and B-D of the bending arm  21  and of the belling device  30 , as well as the by-pass position E. 
     The machine  10  thus configured can therefore be converted from the production of hairpins to the production of segments to be belled, and vice versa, without the need for complicated and long steps of disassembly and/or assembly of accessories or devices. 
     Therefore, the alternation from one type of working to another does not require the intervention of dedicated and specialized personnel and can be performed, for example, via the programming of the command and control unit in a few seconds. 
     The belling device  30  can be configured to move with respect to the tracks defined by the guides  20 , preferably but not limited to, in a manner orthogonal thereto. 
     In other variants, in fact, the belling device  30  can be configured to move in a manner substantially parallel to the tracks defined by the guides  20 . 
     In other embodiments, the machine  10  can be provided with the belling device  30  substantially fixed in one position. In this case, a system for raising and lowering the tracks defined by the guides  20  can be provided, in order to provide for the alignment of the latter with the belling elements  31 . 
     The invention also describes a method to work a plurality of tubes with a multiple-use hairpin bender machine which comprises:
         feeding the plurality of tubes to be worked on the tracks defined by the guides  20 , and   moving the plurality of tubes toward a bending unit  16  and a cutting member  18 ,   performing at least cutting operations on the plurality of tubes.       

     According to one aspect of the invention, the method also comprises:
         aligning with the tracks defined by the guides  20  belling elements  31  of the belling device  30 , and   associating the plurality of tubes with the belling elements  31  in order to perform a belling operation.       

     It is clear that modifications and/or additions of parts may be made to the machine for working tubes as described heretofore, without departing from the field and scope of the present invention as defined by the claims. 
     It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of machine for working tubes, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby. 
     In the following claims, the sole purpose of the references in brackets is to facilitate reading: they must not be considered as restrictive factors with regard to the field of protection claimed in the specific claims.