Abstract:
There is provided a method for producing a friction plate, capable of improving the throughput of friction material and reducing the time and work required for adhering friction material segments to a core plate. The method produces a friction plate having oil grooves communicating between the internal periphery and the external periphery, by fixing friction material segments formed from a friction material to a core plate, and is featured by forming the oil grooves by plastic working of the friction material and fixation of the friction material segments with predetermined gaps therebetween to the core plate.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a method for producing a friction plate adapted for use in an automatic transmission or a lock-up clutch of vehicles such as automobiles and an apparatus therefor.  
         [0003]     2. Related Background Art  
         [0004]     In the prior art, plural segments of friction material are adhered to a core plate with a predetermined gap between the segments, thereby forming oil grooves for lubricating oil on the friction plate.  
         [0005]      FIG. 8  shows an example of such conventional method for producing a friction plate. Segments of the friction material are prepared for example by punching from a tape  5  of the friction material. The segments  3  of the friction material are fixed on a core plate  1  with gaps  4  in the circumferential direction to form a friction plate  10 , and such gaps  4  constitute oil grooves.  
         [0006]     The above-described conventional method for forming the friction plate has been associated with the following drawbacks: 
        1) As the plural segments of the friction material are extracted from the friction material tape and are adhered with predetermined gaps to the core plate, there are required time and work for forming the oil grooves of the required number; and     2) Also as it is necessary to obtain the friction material segments of a relatively large number from the tape, the throughput of the material such as the tape of the friction material is undesirably low, resulting in a significant waste of the material.        
 
       SUMMARY OF THE INVENTION  
       [0009]     In consideration of the foregoing, an object of the present invention is to provide a method for producing the friction plate capable of improving the throughput of the friction material and reducing the time required for adhering the segments of the friction material to the core plate.  
         [0010]     For attaining the above-mentioned object, the present invention is firstly featured by a method for producing a friction plate formed by fixing friction material segments, formed from a friction material, to a core plate and having oil grooves communicating between the internal periphery and the external periphery of the segments: 
        wherein the oil grooves are formed by plastic working of the friction material and fixation of the friction material segments with a predetermined gap therebetween to the core plate.        
 
         [0012]     Also the present invention is secondly featured by a method for producing a friction plate formed by fixing friction material segments, formed from a friction material, to a core plate and having oil grooves communicating between the internal periphery and the external periphery of the segments: 
        wherein the oil grooves are formed by cutting of the friction material and fixation of the friction material segments with a predetermined gap therebetween to the core plate.        
 
         [0014]     Also the present invention is thirdly featured by an apparatus for producing a friction plate formed by fixing friction material segments, formed from a friction material, to a core plate and having oil grooves communicating between the internal periphery and the external periphery of the segments, comprising: 
        means for punching a band-shaped friction material to obtain plural friction material segments;     means for holding the friction material segments by stacking on a metal mold or a jig and pushing out the friction material segments in succession to a side opposite to the metal mold; and     means for pressing and adhering the friction material segments to the core plate;     wherein the oil grooves are formed by plastic working of the friction material and fixation of the friction material segments with a predetermined gap therebetween to the core plate.        
 
         [0019]     Also the present invention is fourthly featured by an apparatus for producing a friction plate formed by fixing friction material segments, formed from a friction material, to a core plate and having oil grooves communicating between the internal periphery and the external periphery of the segments, comprising: 
        means for punching a band-shaped friction material to obtain plural friction material segments;     means for holding the friction material segments by stacking on a metal mold or a jig and pushing out the friction material segments in succession to a side opposite to the metal mold; and     means for pressing and adhering the friction material segment to the core plate;     wherein the oil grooves are formed by cutting of the friction material and fixation of the friction material segments with a predetermined gap therebetween to the core plate.        
 
         [0024]     Also the present invention is fifthly featured by a friction plate formed by fixing friction material segments, formed from a friction material, to a core plate and having oil grooves communicating between the internal periphery and the external periphery of the segments: 
        wherein the oil grooves are formed by plastic working of the friction material and fixation of the friction material segments with a predetermined gap therebetween to the core plate.        
 
         [0026]     Also the present invention is sixthly featured by a friction plate formed by fixing friction material segments, formed from a friction material, to a core plate and having oil grooves communicating between the internal periphery and the external periphery of the segments: 
        wherein the oil grooves are formed by cutting of the friction material and fixation of the friction material segments with a predetermined gap therebetween to the core plate.        
 
         [0028]     Also the present invention is seventhly featured by a friction plate formed by fixing friction material segments, formed from a friction material, to a core plate and having oil grooves communicating between the internal periphery and the external periphery of the segments: 
        wherein the friction material segments are fixed with a predetermined gap therebetween to the core plate and then subjected to cutting for forming the oil grooves.        
 
         [0030]     The time required for adhering work can be reduced since the friction material segments of a number fewer than in the prior art are adhered to the core plate. Also the throughput of the material can be improved.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0031]      FIG. 1  shows a first embodiment of the present invention and is a plan view of the friction plate, showing the mode of adhesion of the friction material segments to the core plate;  
         [0032]      FIG. 2  shows a second embodiment of the present invention and is a plan view of the friction plate, showing the mode of adhesion of the friction material segments to the core plate;  
         [0033]      FIG. 3  shows a third embodiment of the present invention and is a plan view of the friction plate, showing the mode of adhesion of the friction material segments to the core plate;  
         [0034]      FIG. 4  is a plan view of the friction plate produced by the third embodiment;  
         [0035]      FIG. 5  is an elevation view of the friction material segments showing an example of the groove formed therein;  
         [0036]      FIG. 6  is an elevation view of the friction material segments showing another example of the groove formed therein;  
         [0037]      FIG. 7  is a view showing an apparatus for producing the friction plate of the respective embodiments; and  
         [0038]      FIG. 8  is a plan view of the friction plate, showing a conventional method for producing the same.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]     Now the present invention will be explained in detail by preferred embodiments thereof, with reference to the attached drawings, wherein corresponding components are represented by corresponding numbers.  
         [0040]      FIG. 1  shows a first embodiment of the present invention and is a plan view showing the mode of punching plural friction material segments from a tape of the friction material and adhering the segments to an annular core plate. The band-shaped friction material, or the friction material tape  16 , has predetermined thickness and width. Plural friction material segments  11  of a same shape are obtained for example by press punching of the friction material tape  16 .  
         [0041]     The friction material segment  11  has an arc shape, having a predetermined radial width and a predetermined circumferential width. The friction material segment  11  is composed of an external periphery portion  11   a  of a curvature same as that of the annular core plate  12 , an internal periphery portion  11   b , and circumferential edge portions  11   c  for connecting the external periphery portion  11   a  and the internal periphery portion  11   b  at both ends thereof in the circumferential direction.  
         [0042]     The friction material segments  11  are adhered and fixed, for example with an adhesive material, to both top and rear faces of the core plate  12  or a face thereof. In the first embodiment shown in  FIG. 1 , four friction material segments  11  are fixed circumferentially to the core plate  12 . At the adhesion, a predetermined gap is formed between the edges  11   c  of the friction material segments  11  to form oil grooves  14  for the lubricating oil in the automatic transmission.  
         [0043]     As the width of the friction material segments  11  in the radial direction thereof is smaller than that of the core plate  11  in the radial direction thereof, a substantially annular groove  15  is formed on the core plate  12  after the adhesion of the friction material segments  11 . This annular groove  15  communicates with the oil grooves  14 . In case the friction material segments  11  are adhered on both faces of the core plate  12 , respective grooves  15  are naturally formed on both faces thereof. As shown in  FIG. 1 , the friction material tape  16  is provided in advance with a groove  13  by plastic working such as pressing or roller pressing or by cutting. Consequently, the groove  13  is formed in the friction material segment  11  at the preparation thereof for example by punching from the friction material tape  16 . The groove  13  is provided at the approximate center of the friction material segment  11 , penetrating through the segment in the radial direction. Consequently, after the adhesion of the friction material segments  11  on the core plate  12 , the oil grooves  14  and the second oil grooves  13  are positioned radially, with a substantially constant pitch. The grooves  13  also communicate with the annular groove  15 , thus communicating also with the oil grooves  14 .  
         [0044]     In the present embodiment, four friction material segments  11  are adhered to the core plate  12 , but such number is not limited to four and may be selected otherwise. Also the groove  13  provided in the friction material tape  16  need not be limited to one but can also be provided in plural units.  
         [0045]     The friction plate  20  formed by fixing the friction material segments  11  to the core plate  12  is lubricated with lubricating oil in the actual use, and the presence of the groove  15  communicating with the oil grooves  14  and the grooves  13  achieves smooth flow of the lubricating oil, thereby improving the lubricating ability. In particular, there is ensured smooth flow of the lubricating oil in the radial direction from the external periphery side to the internal periphery side of the friction plate  20  and in the opposite direction from the internal periphery side to the external periphery side.  
         [0046]      FIG. 2  shows a second embodiment of the present invention and is a plan view showing the mode of punching plural friction material segments from the friction material tape and adhering the segments to the core plate. As the basic configuration is similar to that in the first embodiment, there will be explained the different points only.  
         [0047]     The friction material segments  11  are adhered and fixed, for example with an adhesive material, to both top and rear faces of the core plate  12  or a face thereof. In the second embodiment, a groove  17  in the friction material segment  11  is not provided in advance on the friction material tape  16  but is formed by plastic working such as pressing at the punching of the friction material segment  11  from the friction material tape  16 .  
         [0048]     Consequently, after the adhesion of the friction material segments  11  on the core plate  12 , the oil grooves  14  and the second oil grooves  17  are positioned radially, at a substantially constant pitch. The grooves  17  also communicate with the annular groove  15 , thus communicating also with the oil grooves  14 .  
         [0049]     In the present embodiment, four friction material segments  11  are adhered to the core plate  12 , but such number is not limited to four and may be selected otherwise. Also the groove  17  formed simultaneously with the punching need not be limited to one but can also be formed in plural units.  
         [0050]     The friction plate  60  formed by fixing the friction material segments  11  to the core plate  12  is lubricated with lubricating oil in the actual use, and the presence of the groove  15  communicating with the oil grooves  14  and the grooves  17  achieves smooth flow of the lubricating oil, thereby improving the lubricating ability. In particular, there is ensured smooth flow of the lubricating oil in the radial direction from the external periphery side to the internal periphery side of the friction plate  60  and in the opposite direction from the internal periphery side to the external periphery side.  
         [0051]      FIGS. 3 and 4  show a third embodiment of the present invention.  FIG. 3  is a plan view showing the mode of punching plural friction material segments from the friction material tape and adhering the segments to the core plate.  FIG. 4  is a plan view of the completed friction plate  70 . As the basic configuration is similar to that in the first embodiment, there will be explained the different points only.  
         [0052]     The friction material segments  11  are adhered and fixed, for example with an adhesive material, to both top and rear faces of the core plate  12  or a face thereof. In the third embodiment, a groove  18  in the friction material segment  11  is not provided in advance on the friction material tape  16  nor formed at the punching of the friction material segment  11  for example by pressing from the friction material tape  16 , but is formed by pressing, roller pressing or cutting after the friction material segment  11  is adhered to the core plate  12 , namely at the final adhesion.  
         [0053]     Consequently, after the adhesion of the friction material segments  11  on the core plate  12 , the oil grooves  14  and the second oil grooves  18  are positioned radially, at a substantially constant pitch. The grooves  18  also communicate with the annular groove  15 , thus communicating also with the oil grooves  14 .  
         [0054]     In the present embodiment, four friction material segments  11  are adhered to the core plate  12 , but such number is not limited to four and may be selected otherwise. Also the groove  18  formed at the final adhesion need not be limited to one but can also be formed in plural units.  
         [0055]     The friction plate  70  formed by fixing the friction material segments  11  to the core plate  12  is lubricated with lubricating oil in the actual use, and the presence of the groove  15  communicating with the oil grooves  14  and the grooves  18  achieves smooth flow of the lubricating oil, thereby improving the lubricating ability. In particular, there is ensured smooth flow of the lubricating oil in the radial direction from the external periphery side to the internal periphery side of the friction plate  70  and in the opposite direction from the internal periphery side to the external periphery side.  
         [0056]      FIGS. 5 and 6  are elevation views of the friction material segment, showing examples of the arrangement of grooves in case of forming plural grooves on the friction material segment  11  for example by pressing. In  FIG. 5 , grooves  19  are formed on the friction material segment  11  in radial manner with a constant pitch in the circumferential direction. On the other hand, in  FIG. 6 , grooves  29  are formed in parallel manner. This configuration, allowing formation of plural grooves in a step, is suitable for example for roller pressing or cutting.  
         [0057]     In  FIGS. 5 and 6 , three grooves are formed in a friction material segment  11 , but another number may naturally be selected.  
         [0058]      FIG. 7  is a schematic view showing the entire configuration of an apparatus  30  for executing the methods for producing the friction plate of the foregoing embodiments. The core plate  12  is supplied from a core plate entry unit  31  of a transporting (transfer) line  53 , and the supplied core plate  12  is transported in a direction X.  
         [0059]     The core plate  12  is then subjected to the coating of the adhesive material on the lower face, by a first adhesive coating device  34  in a first coating unit  33  for coating the adhesive. The core plate, with the adhesive material coated on the lower face, is subjected, in a friction material adhesion unit  35 , to the adhesion, on the lower face, of the friction material segments supplied from a first friction material supply device  44  through a lower face adhesion station  36 .  
         [0060]     Subsequently, the core plate  12  is subjected to the coating of the adhesive material on the upper face, by a second adhesive coating device  38  in a second coating unit  37  for coating the adhesive. The core plate  12 , with the adhesive material coated on the upper face, is subjected, in a friction material adhesion unit  39 , to the adhesion, on the upper face, of the friction material segments supplied from a second friction material supply device  45  through an upper face adhesion station  40 . There are also shown friction material tapes  50  supplied from the friction material supply-devices  44 ,  45 .  
         [0061]     The core plate  12 , bearing the adhered friction material segments on the upper and lower faces, is transported to a discharge unit  41 , then transported to an entry unit  42  for a post process, and is subjected to the simultaneous application of heat and pressure for 15 to 30 seconds for achieving final adhesion in a post process (final adhesion) unit  43  to provide the completed friction plate  55 .  
         [0062]     In  FIG. 7 , the groove  13  of the first embodiment is formed in a step A, while the groove  17  of the second embodiment is formed in a step B, and the groove  18  of the third embodiment is formed in a step D. In a step C, the groove is formed on the friction material segment after the adhesion thereof but prior to the final adhesion, or after the final adhesion.  
         [0063]     As explained in the foregoing, the present invention provides the advantages of: 
        improving the throughput of the friction material; and     reducing the time and process for fixing the friction material segments to the core plate.