Abstract:
A roll feeder for feeding a steel sheet to a processing machine for processing is disclosed to include a rack, which has a hub that supports a roll of steel sheet and is rotated to let off the steel sheet, a roll feeding unit, which has sheet-transfer roller sets for transferring the steel sheet from the rack to the processing machine and a roller leveler for leveling the steel sheet, and a traction unit, which is provided between the rack and the roll feeding unit and controlled to pull the steel sheet from the hub to the roll feeding unit.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to a roll feeder for feeding sheet material, and more particularly, to a roll feeder with a traction unit.  
         [0003]     2. Description of the Related Art  
         [0004]     A conventional roll feeder, as shown in  FIG. 1 , comprises a rack  1 , a roll feeding unit  2 , a roller conveyer  3  provided between the rack  1  and the roll feeding unit  2 , and lifting support  4  mounted in the bottom side of the rack  1  and adapted to support the steel sheet and the guide the steel sheet to the roll feeding unit  2 .  
         [0005]     This design of roll feeder has numerous drawbacks as outlined hereinafter:  
         [0006]     1. Material feeding requires an experienced worker. When the steel sheet  5  is let off from the rack  1 , it is difficult to guide and transfer the curved leading end of the steel sheet  5  to the roll feeding unit  2 . Only an experienced worker can properly control the rack  1 , the lifting support  4  and the guide frame  6  of the roller conveyer  3  to transfer the steel sheet  5  to the roll feeding unit  2  smoothly.  
         [0007]     2. It takes a long time to feed the material. During feeding operation, the worker must carefully control the speed to let off the steel sheet  5  and the lifting elevation of the lifting support  4  and the swinging angle of the guide frame  6  of the roller conveyer  3  so that the steel sheet  5  can smoothly be guided into the roller conveyer  3  and carried by the roller conveyer  3  to the roll feeding unit  2 .  
         [0008]     3. The lead end of the steel sheet  5  may curve upward during delivery, causing an accident. When lifting the lifting support  4  to guide the lead end of the steel sheet  5  into the roller conveyer  3 , the worker must control the air cylinder  7  to adjust the swinging of the guide frame  6 . In proper control of the guide frame  6  may let the lead end of the steel sheet  5  curve upward suddenly, resulting in an accident.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention has been accomplished under the circumstances to provide a roller feeder, which eliminates the aforesaid problem. It is therefore the main object of the present invention to provide a roll feeder, which automatically pulls the supplied steel sheet to the roll feeding unit for feeding to save operating time. It is another object of the present invention to provide a roll feeder, which automatically flatten the feeding steel sheet, preventing the lead end of the steel sheet from curving upwards.  
         [0010]     To achieve this and other objects of the present invention, the roll feeder comprises a rack, a roll feeding unit, and a traction unit. The rack comprises a hub adapted to support a roll of steel sheet and to let off the steel sheet. The roll feeding unit is adapted to transfer the steel sheet from the rack, comprising two sheet-transfer roller sets adapted to transfer the steel sheet, and a roller leveler set between the two sheet-transfer roller sets and adapted to level the steel sheet. The traction unit is provided between the rack and the roll feeding unit and adapted to pull the steel sheet from the hub to the roll feeding unit. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a side view of a roll feeder according to the prior art.  
         [0012]      FIG. 2  is a side view of a roll feeder according to the present invention.  
         [0013]      FIG. 3  is an enlarged view of a part of the present invention, showing the tractor seized the lead end of the steel sheet.  
         [0014]      FIG. 4  is a schematic drawing of the present invention showing the tractor pulled the steel sheet toward the roll feeding unit.  
         [0015]      FIG. 5  is similar to  FIG. 4  but showing the rammer operated.  
         [0016]      FIG. 6  is a schematic drawing of the present invention, showing the steel sheet delivered through the traction unit, the rammer, and the roll feeding unit.  
         [0017]      FIG. 7  is an enlarged view of a part of the present invention, showing an alternate form of the tractor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     Referring to  FIG. 2 , a roll feeder in accordance with the present invention is shown comprised of a rack  10 , a roll feeding unit  20 , a traction unit  30 , and a rammer  40 .  
         [0019]     The rack  10  comprises a hub  11 , an expander  12  provided at the center of the hub  11  and adapted to expand and support a roll of steel sheet on the hub  11 , a limiter  13  disposed at one side of the hub  11  and adapted to limit the position of the steel sheet on the hub  11  by means of an air pressure, a holding down device  14  disposed at one side of the hub  11  opposite to the limiter  13  and adapted to hold down the steel sheet on the hub  11 , and a lifting support  15  spaced below the hub  11  and adapted to support the steel sheet. A respective air cylinder drives the holding down device  14  and the lifting support  15 .  
         [0020]     The roll feeding unit  20  is provided behind the rack  10 , comprising a first sheet-transfer roller set  21  and a second sheet-transfer roller set  22  adapted to transfer the steel sheet from the hub  11 , and a roller leveler  23  provided between the first sheet-transfer roller set  21  and a second sheet-transfer roller set  22  and adapted to level the curving part of the steel sheet.  
         [0021]     The traction unit  30  is provided between the rack  10  and the roller feeding unit  20  and adapted to pull the steel sheet from the rack  10  toward the roller feeding unit  20 .  
         [0022]     The traction unit  30  comprises a material receiver  301 , which is a material entrance having a width gradually increasing toward the rack  10 , a track  31  extending from the material receiver  301  to the first sheet-transfer roller set  21  of the roller feeding unit  20 , a tractor  32  movable between two ends of the track  31  and adapted to pull the steel sheet from the material receiver  301  to the first sheet-transfer roller set  21  of the roller feeding unit  20 , a plurality of sprockets  33  arranged around the track  31 , a transmission chain  34  mounted on the sprockets  33 , a drive chain  36  coupled to one of the sprockets  33 , a motor  35  adapted to drive the drive chain  36 , and a plurality of guide rollers  37  mounted in the track  31  and adapted to guide the steel sheet forward.  
         [0023]     The rammer  40  is installed in the track  31  and adapted to flatten the steel sheet, comprising a movable upper ramming die  41 , a fixed bottom die  42 , a first hydraulic cylinder  43  controlled to reciprocate the movable upper ramming die  41  relative to the fixed bottom die  42 , a pressure roller  44  adapted to stop the transferring steel sheet from curving upwards, a second hydraulic cylinder  45  controlled to adjust the elevation of the pressure roller  44 , a motor  46 , and a chain  47  driven by the motor  46  to rotate the pressure roller  44 .  
         [0024]     Referring to  FIG. 3 , the tractor  32  comprises a body  321 , which has an opening  322  facing the material receiver  301 , a fixed jaw  323  fastened to the top side of the opening  322 , a movable jaw  324  pivoted to the bottom side of the opening  322 , and sprocket means  341  provided at the body  321  and meshed with the transmission chain  34  for enabling the tractor  32  to work with the sprockets  33  and the transmission chain  34 . The fixed jaw  323  and the movable jaw  324  have teeth for grasping the transferring steel sheet in the opening  322 .  
         [0025]     Referring to  FIGS. 2 and 3  again, after loading of a roll of steel sheet on the hub  11 , the expander  12 , the limiter  13 , the holding down device  14  and the lifting support  15  are respectively operated. During continuous rotation of the hub  11  to let off the steel sheet, the lead end A of the steel sheet falls to the lifting support  15 , which lifts the lead end A of the steel sheet to the material receiver  301  of the traction unit  30 . When the lead end A of the steel sheet entered the opening  322  of the tractor  32  at the first end of the track  31 , the traction unit  30  is started to catch the lead end A of the steel sheet with the fixed jaw  323  and the movable jaw  324  and to further pull the lead end A of the steel sheet forward. The material receiver  301  comprises two swinging frames  302 , 303  respectively pivoted to the traction unit  30 . The swinging frames  302 , 303  have a respective curved panel  304 , 305  arranged in a double-bevel manner.  
         [0026]     Referring to  FIG. 4 , during continuous rotation of the hub  11  of the rack  10 , the steel sheet is gradually loosened from the hub  11 , and the tractor  32  pulls the lead end A of the steel sheet to the first sheet-transfer roller set  21  of the roller feeding unit  20 . After the tractor  32  seized the lead end A of the steel sheet, the swinging frames  302 , 303  are turned outwards relative to each other to move the curved panels  304 , 305  apart, preventing friction between the curved panels  304 , 304  and the transferring steel sheet.  
         [0027]     Referring to  FIG. 5 , during continuous operation of the roller feeder, the lead end A of the steel sheet is moved through the rammer  40 . At this time, the first hydraulic cylinder  43  is controlled to reciprocate the movable upper ramming die  41  relative to the fixed bottom die  42  to ram the transferring steel sheet to a flatten status, and at the same time the tractor  32  continuously pulls the lead end A of the steel sheet to the first sheet-transfer roller set  21  of the roller feeding unit  20 . When the tractor  32  is approaching the first sheet-transfer roller set  21  of the roller feeding unit  20 , the second hydraulic cylinder  45  is controlled to press the pressure roller  44  on the transferring steel sheet against the guide rollers  37  to prevent backward displacement of the transferring steel sheet upon release of the tractor  32  from the lead end A of the steel sheet.  
         [0028]     Referring to  FIG. 6 , after having moved to the second end of the track  31 , the tractor  32  releases the transferring steel sheet. Because the second end of the track  31  slopes at an angle, the tractor  32  does not hinder forward delivery of the transferring steel sheet. Following rotation of the hub  11  of the rack  10  and the pressure roller  44 , the lead end A of the steel sheet is moved into the first sheet-transfer roller set  21  of the roller feeding unit  20 , and then leveled by the roller leveler  23  carried forwards by the second sheet-transfer roller set  22  for further processing by a processing machine.  
         [0029]      FIG. 7  shows an alternate form of the tractor according to the present invention. According to this embodiment, the lead end A of the steel sheet has at least one hole A 1 , and the tractor  32  has at least one peg  38  for engaging the at least one hole A 1  upon passing of the lead end A of the steel sheet into the traction unit  30 .  
         [0030]     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.