Abstract:
A bar feeder for feeding a machine tool, particularly for feeding with bars a single-spindle automatic lathe, comprising a horizontal supporting beam for a plurality of free rollers, which lie on a horizontal plane and form a substantially V-shaped channel for the longitudinal support of a bar, said beam being movable vertically parallel to itself, adjustment means being provided for vertically adjusting said beam in order to align said bar with the axis of said lathe.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a bar feeder for feeding machine tools. It is known that bar feeders used to feed machine tools, such as single-and multiple-spindle automatic lathes, comprise a guiding channel in which the bars are individually inserted and made to advance toward the lathe.  
           [0002]    Since the bars must be arranged in the channel so as to be coaxial to the machining axis of the lathe (hereinafter referenced as the lathe axis), it is necessary to often replace the channel according to the diameter and shape of the bars.  
           [0003]    This fact entails the availability of a range of channels and complex operations for replacement and setup of the feeder in order to achieve correct support of the bars of different diameters and perfect alignment with the lathe axis.  
         SUMMARY OF THE INVENTION  
         [0004]    The aim of the present invention is to provide a feeder that allows to feed bars of any diameter without requiring replacement of the guiding channel every time the diameter of the bar to be machined in the lathe changes.  
           [0005]    Within this aim, an object of the present invention is to provide a feeder that is capable of feeding not only cylindrical bars but also bars having a polygonal cross-section.  
           [0006]    This aim and this and other objects that will become better apparent hereinafter are achieved with a bar feeder for feeding a machine tool, particularly for feeding with bars a single-spindle automatic lathe, characterized in that it comprises a horizontal supporting beam for a plurality of free rollers, which lie on a horizontal plane and form a substantially V-shaped channel for the longitudinal support of a bar, said beam being movable vertically parallel to itself, means being provided for vertically adjusting said beam in order to align said bar with the axis of said lathe. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    Further characteristics and advantages of the present invention will become apparent from the description that follows of a preferred embodiment thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein:  
         [0008]    [0008]FIG. 1 is a plan view of the feeder;  
         [0009]    [0009]FIG. 2 is a lateral elevation view;  
         [0010]    [0010]FIGS. 3 and 4 are two enlarged-scale views showing the adjustment means for vertically adjusting the roller supporting beam in two active positions in a configuration for small-diameter bars;  
         [0011]    [0011]FIGS. 5 and 6 are two sectional views, taken along the lines V-V and VI-VI of FIGS. 3 and 4, respectively;  
         [0012]    [0012]FIG. 7 is a perspective view showing the adjustment means for vertical adjustment of the roller supporting beam;  
         [0013]    [0013]FIGS. 8 and 9 are views showing two different types of roller that form the guiding channel; and  
         [0014]    [0014]FIGS. 10 and 11 are views, similar to FIGS. 3 and 4, but in the configuration suitable for large-diameter bars. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    With reference to the figures, the feeder comprises a longitudinal member  1 , which connects two mutually opposite shoulders  2  and  3  and is supported by a footing  4 . The longitudinal member  1  has an L-shaped cross-section (see FIGS. 5 and 6), with a vertical wall  5  and a wall  6  that protrudes horizontally from the wall  5 .  
         [0016]    To the side of the vertical wall  5  there are two vertical guides  7 , in which two respective flat strips  8  are guided; a beam  9  is fixed to the top of said strips and has a box-like U-shaped cross-section. The beam  9  is parallel to the longitudinal member  1  and lies above it, and comprises a compartment  10 , which is open upward and rotatably supports multiple free parallel rollers  11 . The rollers  11  are shaped like an hourglass (see FIG. 8 in particular), composed of two mutually opposite frustums  12 ,  13 , which are tangent to two planes which form a V-shaped guiding channel  14 . The numeral  15  designates a chute, which protrudes obliquely from one edge of the beam  9 , and has the function to convey the bar to be machined into the channel  14 .  
         [0017]    A linkage  16  is arranged in front of the two strips  8  so that it can slide and be guided horizontally; said linkage is parallel to the longitudinal member  1  and is connected, by means of brackets  17 , to a rack  18 , which can slide in a guide provided on the horizontal wall  6  of the longitudinal member  1 .  
         [0018]    The rack  18  meshes with the pinion of a reversible motor assembly M which is capable of imparting to said rack, and therefore to the linkage  16 , a stroke having a preset length.  
         [0019]    The linkage  16  has, at its opposite ends, supports  19  for a threaded rod  20 , which can be actuated by means of a crank  21  (see FIGS. 1, 2) rotatably supported in the side  2 . The rod  20  is rotationally coupled to the crank  21  by means of a telescopic coupling, which allows the rod to follow ¢ the movements of the linkage  16  caused by the actuation imparted thereto by the rack  18 .  
         [0020]    The linkage  16 , with respective plates  16 a associated therewith by means of spacer pins  16   b , forms two guides, in which two respective sliding blocks  22  can slide; said sliding blocks have respective threaded seats, through which the rod  20  is guided with a threaded coupling. Accordingly, the actuation of the crank  21  produces the movement of the sliding blocks  22  with respect to the linkage  16  and therefore with respect to the strips  7 .  
         [0021]    A respective L-shaped element  23  is fixed to each sliding block  22 , and a respective channel-shaped cam  24  is rigidly coupled to the top of said L-shaped element. The cams  24  are constituted by a C-shaped profiled element, which is open toward the strips  8 , and the lower end of said cams is open in order to receive a follower roller  25 , which protrudes from the respective strip.  
         [0022]    As clearly shown by FIGS. 5 and 6, the bar B to be inserted in the lathe, fed from a magazine by means of the chute  15 , is deposited in the guiding channel  14 , where the V-shaped cross-section of the channel keeps it perfectly positioned in the vertical plane P (see FIG. 8) that passes through the lathe axis A.  
         [0023]    Adjustment means are thus provided for vertically adjusting the beam  9 , to align bars B with the axis of the lathe.  
         [0024]    Vertical alignment of the axis of the bar B with the axis A of the lathe is performed by actuating the rack  18 , which moves the linkage  16  with such a stroke as to cause the engagement of the two follower rollers  25  in the cams  24  and therefore, as a consequence of the oblique orientation of said cams, the lifting of the strips  8  to the intended level of alignment with the lathe axis A.  
         [0025]    The described feeder therefore achieves the intended aim and object. In particular, as shown in FIG. 8, the V-shaped cross-section of the groove of the rollers ensures the arrangement of the bars on the plane P regardless of their diameter.  
         [0026]    In the case of bars B 2  having a large diameter (see FIGS. 10 and 11), the adjustment performed with the rod  20  allows to move the sliding blocks  22  away from the follower rollers  25 . This allows to cancel out part of the stroke performed by the rollers as a consequence of the actuation of the linkage  16  and therefore ultimately allows to reduce the upward stroke of the bar B 2 , whose axis, owing to the larger diameter, is already displaced further upward toward the lathe axis.  
         [0027]    The described feeder is susceptible of numerous modifications and variations which are to be considered technically equivalent to the ones defined by the appended claims.  
         [0028]    For example (see FIG. 9), the rollers  11  can have a central groove formed by control frustums  26 ,  27  that converge toward their rotation axis A with an angle that is larger than the angle of the lateral frustums  12 ,  13 . In this manner, it is possible to delimit guiding grooves  28  for polygonal bars B 1 . FIG. 8 illustrates an example of rollers for guiding bars having a square cross-section, regardless of their size.  
         [0029]    In the practical embodiment of the invention, the actuation of the threaded rod  20  can occur with the aid of a motor assembly instead of manually.  
         [0030]    Advantageously, the bar guiding channel  14  is composed of a plurality of modules  29  (see FIGS. 1, 2 and  7 ), each of which comprises a beam portion  9  which supports a preset number of rollers  11 . The portions are provided with pins  30 , which are suitable to be inserted in seats  31  of a longitudinal member  32  that joins the strips  8  at the top.  
         [0031]    The disclosures in Italian Patent Application No. BO2001A000029 from which this application claims priority are incorporated herein by reference.