Abstract:
A bar feeder for feeding an automatic lathe, comprising a bar magazine and a guide supplied by the magazine, a facing device being associated with the end of the magazine that lies opposite to the end that is adjacent to the lathe and being suitable to machine the rear end of the bar on which the bar pusher engages.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a bar feeder provided with a bar facing device.  
           [0002]    As it is known, in feeders used for feeding automatic lathes, the bar to be machined is taken from a magazine and placed in a guiding channel along which a pusher element, known as bar pusher, moves. Said bar pusher acts on the rear end of the bar and causes it to advance in successive steps which are equal in length to the machined parts to be obtained.  
           [0003]    With these feeders it is not possible to machine the last portion (end segment) of the bar; since said portion cannot be gripped by the collet of the lathe because the bar has been used up, it is allowed to drop, causing problems for removing it from the lathe.  
           [0004]    Bar feeders are also known in which the end portion of the bar can be recovered by fitting the bar pusher with a specifically provided collet suitable to grip the rear end of the bar inserted in the guiding channel. Thereby, when the bar is used up, the end portion remains attached to the collet and can be recovered when the bar pusher is retracted. However, in said bar feeders the outside dimensions of the collet must be greater than the diameter of the bar and therefore there are considerable problems in providing the guide in order to prevent vibrations and noise due to knocking inside said guide.  
           [0005]    It should also be noted that the bars are available with opposite ends that have uneven regions due to cropping. These uneven regions, in order to avoid off-centering upon engagement of the bar pusher, are often removed by subjecting the bar to preliminary facing in a machine tool, hence with considerable additional costs.  
         SUMMARY OF THE INVENTION  
         [0006]    The aim of the present invention is to provide a feeder equipped with a device which is suitable to perform the facing of the rear end of the bars within the machining cycle of said bars and therefore with a significant reduction in machining costs.  
           [0007]    Within this aim, an object of the present invention is to provide a feeder equipped with a device which is suitable to prepare the rear end of the bars so as to allow to use a bar pusher provided with a collet having diametrical dimensions that do not exceed the dimensions of the bar to be machined thereby allowing to recover the end portion of the bar and also eliminate vibration and noise.  
           [0008]    This aim and this object are achieved with a bar feeder for feeding an automatic lathe, comprising a bar magazine and a guide supplied by said magazine, characterized in that a facing device is associated with the end of said magazine that lies opposite the end that is adjacent to said lathe and is suitable to machine the rear end of the bar on which the bar pusher engages.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    Further characteristics and advantages of the present invention will become better apparent from the following description illustrated in the accompanying drawings, wherein:  
         [0010]    [0010]FIG. 1 is a schematic elevation view of a bar feeder according to the invention;  
         [0011]    [0011]FIG. 2 is a sectional view, taken along the line II-II of FIG. 1;  
         [0012]    [0012]FIG. 3 is a sectional view, taken along the line III-III of FIG. 2;  
         [0013]    [0013]FIG. 4 is a perspective view of the facing device according to a first embodiment;  
         [0014]    [0014]FIG. 5 is a partial perspective view of the device;  
         [0015]    [0015]FIG. 6 is a longitudinal sectional view of the device;  
         [0016]    [0016]FIG. 7 is a perspective view of the footing of the device;  
         [0017]    [0017]FIGS. 8 and 9 are two perspective views, taken from opposite sides, of a unit of the device;  
         [0018]    [0018]FIGS. 10, 11 and  12  are axial sectional views, taken along the lines X-X, XI-XI, XII-XII of FIG. 6;  
         [0019]    [0019]FIG. 13 is a perspective view of a second embodiment of the device according to the invention;  
         [0020]    [0020]FIG. 14 is a longitudinal sectional view of the device of FIG. 13;  
         [0021]    [0021]FIG. 15 is a plan view of a device according to a further variation;  
         [0022]    [0022]FIG. 16 is a transverse sectional view of a modified bar feeder.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    With reference to FIGS.  1  to  3 ,  1  generally designates a conventional bar feeder; its magazine  2  for the bars B to be machined and the guide  3  along which the bars are guided to the lathe in which they are subjected to the intended machining are pointed out in order to clarify the present invention.  
         [0024]    The expression “bars B” is understood to designate solid rods having a circular or polygonal cross-section and pipes.  
         [0025]    The magazine  2  comprises an inclined surface  4  for supporting the bars B which is supported by the frame  5  of the bar feeder, which rests on the ground by means of posts  6 . By way of known singling-out means, not shown, the lowermost bar B is released from the magazine in order to be inserted in the guide  3 . In order to receive the bar, the guide  3  is composed of two half-shells  7  and  8  which are mutually pivoted and actuated by appropriate actuators, which are known and therefore are not illustrated, between an open position (shown in dashed lines in FIG. 2), which allows the released bar to enter the guide, and a closed position, in which the two half-shells  7  and  8  define a closed channel  9  which allows a bar pusher to make the bar advance in steps towards the lathe  10 .  
         [0026]    A side wall  11  is rigidly coupled to the surface  4 , at the opposite end with respect to the lathe  10 , and a device  12  is mounted thereon: said device performs the facing of the bars arranged on the surface  4 . It should be noted that the term “facing” is used to designate any machining performed on the end of the bar which entails chip-forming, such as turning, boring, or drilling.  
         [0027]    The device  12  (FIGS. 4 and 6) comprises a footing being shaped like a half-box  13  (FIG. 7) rigidly coupled to a plate  14  by means of which it is fixed with screws  15  to the side wall  11  so as to cantilever out. The half-box  13  has two parallel walls, on the upper edges whereof two parallel rails  16  are fixed; the sliders  17  (FIGS. 4 and 5) of a movable unit  18  slide on said rails.  
         [0028]    Said unit  18  comprises a cylindrical shell  19  inside which a sleeve  22  (FIG. 10) is rotatably supported according to the axis A by means of bearings  20  and  21 . An interspace  23  remains between the sleeve  22  and the cylindrical shell  19  and accommodates, in an intermediate position, a ring gear  24  with internal teeth which is fixed to an internal collar of the shell  19 .  
         [0029]    The sleeve  22  encloses a cylindrical cavity  25  whose axis C is eccentric with respect to the axis A. A hollow shaft  28  is rotatably supported in said cavity  25  by means of bearings  26  and  27 , and a gear  29  is keyed on said shaft.  
         [0030]    The keying of the gear  29  on the shaft  28  is rotationally provided by means of a key  30  and is axially provided by means of spacer bushes  31  and  32  which lie between the gear  29  and the bearings  26  and  27 .  
         [0031]    The gear  29  meshes with the gear  24  by means of an opening  33  which covers an arc of the sleeve  22 .  
         [0032]    The hollow shaft  28  has an end, the right one in FIG. 6, which protrudes out of the sleeve, and a pulley  34  is rotationally rigidly coupled thereon. A belt  35  is wound around the pulley  34  and is closed in a loop around a second pulley  36  keyed on the output shaft of a motor  37  mounted on a flange  38  which rises from the cylindrical shell  19 .  
         [0033]    The transmission composed of the belt  35  and the pulleys  34 ,  36  is covered by a housing  39  which is fixed to the flange  38  by means of screws  39   a.    
         [0034]    The hollow shaft  28 , at the end that lies opposite the pulley  34 , is preset for the coupling of a tool  40  which, in the illustrated example, is of the type suitable to perform the external machining of a bar B which is aligned with the axis A, transferred from the magazine  2  and is arranged in front of it.  
         [0035]    The bar B is machined by combining the axial movement of the unit  18  with the rotation of the tool  40 .  
         [0036]    Axial movement is actuated by a fluid-actuated jack  41  accommodated in the half-box  13  below the unit  18  and in which the cylinder is rigidly coupled to the head wall  42  of the half-box and the stem acts on a lug  43  which protrudes downwards from the shell  19 . By activating the jack  41 , the unit  18  is moved axially along the rails  16 . At the same time, the rotation imparted to the hollow shaft  28  by the motor  37  determines, due to the eccentricity of the axis C of the shaft  28  with respect to the axis A of the sleeve  19  and due to the meshing of the gears  24 ,  29 , an orbital movement of the hollow shaft  28  and therefore of the tool  40  and the gradual removal of an outer layer S of the end of the bar B. The chips formed during this machining are collected by a housing  44  which surrounds the tool  40 , leaving a front opening for the bar B, and are collected in a container  45  fixed below the half-box  13 .  
         [0037]    In order to position the bar B in front of the tool  40 , the described device  12  provides for a translatory assembly  46 , which picks up the bar B from the magazine  2  and moves it toward the tool by a preset extent, and a locking assembly  47  which keeps the bar locked during machining.  
         [0038]    The translatory assembly  46  comprises (FIGS. 8 and 9) two rods  48  which are parallel to the axis A and are fixed to the plate  14  so as to cantilever out. The rods  48  are connected one another by a cross-member  49  on which an actuator  50  is fitted; said actuator is constituted by a fluid-actuated jack whose stem  51  is connected to a carriage  52  which can slide on the rods  48 .  
         [0039]    Two pivots  53  and  54  are pivoted in the carriage  52  and are perpendicular to the rods; on the opposite sides of the carriage, said pivots support respective arms  55 ,  56  and  57 ,  58 .  
         [0040]    The arms  57 ,  58  are articulately connected to a block  59  which is fixed to the stem  60  of a jack  61  whose axis is parallel to the rods  48 .  
         [0041]    The jack  61  is coupled, by means of a flange, to an L-shaped element  62  being fixed laterally to the carriage  52 .  
         [0042]    The arms  55 ,  56  have, at their ends, jaws  63 ,  64  which are constituted by cylinders which are parallel to the pivots  53 ,  54 .  
         [0043]    As will become better apparent hereinafter, by activating the jack  61  the jaws  63 ,  64  are actuated so as to grip the end of a bar B which is arranged between them, whereas by activating the jack  50  the bar B performs an advancement stroke towards the tool  40  through an opening of the side wall (not shown in the drawings) and an opening  65  (FIG. 7) of the plate  14 .  
         [0044]    After passing through the plate  14 , the bar B is gripped by the assembly  47 , which as shown more clearly in FIG. 12 comprises two sliders  66  and  67  which can slide in respective guides  68  and  69  rigidly coupled to the plate  14  and have mutually opposite jaws  70  and  71 .  
         [0045]    The sliders  66  and  67  are moved in opposite directions one another by means of two levers  72  and  73  which are pivoted in a rocker-like manner on pivots  74  and  75  rigidly coupled to the plate  14 . The levers  72  and  73  have an arm which is pivoted in the sliders  66  and  67  and another arm which is pivoted in an element  76  rigidly coupled to the end of the stem  77  of a double-acting fluid-actuated jack  78  which is fitted inside the half-box  13 , between the plate  14  and the housing  44 .  
         [0046]    The operation of the described bar feeder is evident from the above description and can be summarized as follows. By virtue of an appropriate singling-out unit of a type widely used in the manufacture of bar feeders, the last bar, i.e. the bar B 1 , i.e. the lowest among the ones arranged on the inclined surface  4  of the magazine  2 , is spaced from the others and aligned with the jaws  63  and  64  of the translatory assembly  46 .  
         [0047]    In a first step, the carriage  52  is actuated into a position in which the jaws  63  and  64 , when the jack  61  is activated, grip the end of the bar B 1  and then, when the jack  50  is activated, transfer it in front of the tool  40 .  
         [0048]    In this position, the jack  78  is activated and locks the bar by actuating the jaws  70  and  71 .  
         [0049]    The subsequent step provides for the advancement of the unit  18  by means of the jack  14  and the facing of the bar by means of the tool  40 . Once said machining has ended, the return of the unit  18  is actuated and the jaws  70  and  71  are released, so as to allow to reposition the bar in the magazine.  
         [0050]    It is evident that the invention fully achieves the intended aim and object. In particular, it should be noted that the facing of the bar occurs while another bar is being machined in the lathe, i.e., with a considerable cost saving.  
         [0051]    Another considerable advantage is the use of a facing device which, by virtue of the orbital motion of the tool, forms small chips which as such are easy and practical to remove.  
         [0052]    The invention is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.  
         [0053]    [0053]FIGS. 13 and 14 illustrate a facing device in which the components that are identical or equivalent to those of the device of FIGS.  4 - 12  are designated by the same reference numerals increased by 100. The assemblies  146  and  147  are fully identical.  
         [0054]    The differences consist in that the advancement of the tool  140  is achieved not by moving the unit  118 , as in the preceding example, but by rotatably supporting the shaft  128  coaxially in the sleeve  122  and guiding said sleeve axially into the shell  119  without turning about its own axis.  
         [0055]    For this purpose, the sleeve  122  is externally provided with an axial groove  79  which is engaged by a pin  80  protruding inside the shell  119 . In order to allow the movement of the sleeve  122 , on the outside of said sleeve there is a collar  81  which slides sealingly in a seat  82  provided in the internal wall of the shell  119 . The collar  81  constitutes, in practice, a piston which divides the seat  82  into two chambers which are connected to the delivery and the return of a pressurized liquid, so as to determine the advancement of the sleeve  122  and of the tool  140  toward the bar B in order to perform facing and then retract the tool once facing has been completed.  
         [0056]    Another variation of the device of FIGS. 13 and 14, shown in FIG. 15, entails machining the bar directly on the surface  4  of the magazine  2 , so that the translatory assembly  146  is no longer necessary.  
         [0057]    In this variation, the locking assembly  147  is arranged on the opposite side of the plate  114  so that its jaws can move at right angles to the surface  4  in order to allow, in the open condition, the ends of the bars to pass between them and allow, in the closed condition, the bar to be machined to stop in alignment with the axis A. Once the bar has been locked, the unit  118  can be made to advance in order to perform facing.  
         [0058]    The device of FIG. 15 is particularly suitable for performing facings consisting of a simple axial hole of the bar, which can be provided by means of a drilling tool  83 .  
         [0059]    Still another variation of the invention, shown in FIG. 16, uses on the surface  4  of the magazine  2  a toothed spacer  84  which is suitable to maintain mutual separation of the bars B arranged on the surface  4 , in order to allow the arrangement of the translatory assembly  46  and the machining of the bar that lies upstream of the lowermost bar.  
         [0060]    The disclosures in Italian Patent Application No. BO99A000687 from which this application claims priority are incorporated herein by reference.