Abstract:
A polycrystalline diamond drill bit for percussion drilling, in small hole high silica ground. The bit is made having a bit body, and a series of inserts locating in the bit body, and the bits are made using a double chisel design, or a modified double chisel design. The inserts are either chiseled shaped inserts, or the inserts are a combination of chisel shaped inserts and conical inserts, and are set into the bit body at very specific angles, in order to attain slicing of the earth when percussion drilling is performed. The inserts have specific lengths to cut clearance for the bit body. The cutting angle and the radius of the tip of each insert in addition to the diameter of the inserts, provide for use of a machine thrust pressure and machine torque pressure at low ranges when the PCD bits are used in percussion drilling.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This non-provisional patent application claims priority as a continuation-in-part of the non-provisional patent application having Ser. No. 13/987,893, filed on Sep. 16, 2013, and which is the non-provisional patent application for the provisional patent application having Ser. No. 61/744,090, filed on Sep. 18, 2012, and the former application having Ser. No. 13/987,893 claims priority as a continuation-in-part to the patent application having Ser. No. 12/550,093, filed on Aug. 28, 2009, which claims priority as a CIP to the non-provisional patent application having Ser. No. 12/273,700, filed on Nov. 19, 2008, which claims priority to the provisional patent application having Ser. No. 61/022,614, filed on Jan. 22, 2008. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to drill means, and more specifically to polycrystalline diamond drill bit means, incorporating inserts of the chisel design type, or a combination of chisel design and conical inserts, having PCD applied to their upper surfaces, and for use for accelerating drilling, particularly within very hard rock, and high silica ground in very low thrust and torque ranges. The invention comprises very specific parameters for the drill bits and drill machine settings that comprise an enhanced system for drilling. 
       BACKGROUND OF THE INVENTION 
       [0003]    Tungsten carbide drill bits have been used for drilling into soil and also hard rock, and have been available for many years, have been effective for their routine usage, but they do have a tendency to become dull, or fracture, particularly when drilling into hard rock. 
         [0004]    Current tungsten carbide bits tend to dull down very fast in very hard, high silica ground, with a compressive strength of 30,000-60,000 psi. 
         [0005]    The drill settings, when using tungsten carbide bits are generally set at 30 Bar or more for the thrust and torque for the first hole or two, then the thrust is increased to the maximum on the drill of approximately 50 Bar, to drive the dull bit into the rock. 
         [0006]    Tungsten carbide bits cannot drill efficiently at very low thrust and torque settings in hard rock drilling applications, as the carbide inserts dull down severely, and stop the drill bit from penetrating the ground. Very high thrust and torque settings, sometimes up to 50 Bar, as aforesaid, are required when drilling with these types of carbide bits. 
         [0007]    The prior art and use of tungsten carbide insert bit designs has proven to be marginally satisfactory and the design and use of polycrystalline diamond (PCD) type inserts has substantially improved the performance of percussion drill bits. It has taken many years to perfect the design of the PCD bits, as a replacement for carbide tips, particularly since in the PCD bit structure, the range for the dimensions of the inserts, the bit bodies, and the drill settings, are very limited and narrow. Inserts used in prior art could have a very wide range of dimensions, and still be considered acceptable. 
         [0008]    Prior art patents or publications include U.S. Pat. No. D574,403 and U.S. Publication No 2009/0184564. Other prior art patents relating to this technology include U.S. Pat. No. 5,944,129, in addition to U.S. Pat. No. 3,788,409. 
         [0009]    As further commented, carbide bits operate at very high thrust and torque, usually in the range of 30 to 50 Bar or above for thrust, and 30 Bar or above for torque, and their insert tip length is shorter, and there are many more inserts included in the bit body, than are required or needed in the PCD type of percussion drill bit. 
         [0010]    Carbide bits dull down fairly fast, particularly in abrasive rock, thus slowing down the penetration rate, and require a significant elevation of thrust and torque, in order to achieve any continuous drilling. Furthermore, it has been experienced that carbide bits wear down 10 to15 times faster than a PCD drill bit, and are 30% to 50% slower in drilling penetration rates. This make for quite a difference. 
         [0011]    Through testing, it has been determined that the normal time to drill a 50 hole round within hard rock, using the carbide drill bit, was in excess of three hours, but utilizing a PCD insert drill bit, could achieve the same drilling of a 50 hole round in a time between about one hour and one and a half hours. PCD bits complete a drilling operation using 70% less thrust and 60% less torque. 
         [0012]    The usage of PCD bits, in comparison to carbide bits, found that the PCD percussion drill bits were more productive; at far less thrust and torque parameters, than the carbide bits. 
         [0013]    Furthermore, because there are fewer PCD bits to change out due to little or no dulling, during prolonged usage, there is a lesser chance of injuries to the miner, and workers handling such equipment. 
         [0014]    Because of the reduction in thrust and torque forces required, up to approximately the 70% range, when drilling with PCD insert drill bits in comparison to the use of carbide bits, there is less heat buildup in the drill steel sections and there is a less torsional forces exerted on the steel sections that can cause fatigue and failure, and therefore, the drill steel section life of the entire equipment is vastly improved using the PCD insert bits. 
         [0015]    Furthermore, because of the very low thrust and low torque that is used when drilling with PCD double chisel insert bits or modified double chisel bits, as has been found through experimentation, there is less stress on the hydraulic components of the machinery, that there is less wear on the drilling machine and there is less heat buildup in the drill steel sections, as explained, when utilizing the PCD bits in comparison with carbide bits. 
         [0016]    Other patents relating to the subject matter of this invention, as previously briefly reviewed, can be seen in the earlier patents to the inventor herein, U.S. Pat. No. D574,403, to Brady, upon the development relating to Hard Rock Percussion Drill Bit With Parabolic PCD Inserts; a further published application to Mr. Brady, U.S. 2009/0184564, upon PCD Percussion Drill Bit; the prior published application to the inventor herein entitled PCD Percussion Drill Bit, No. U.S. 2010/0025114, disclosing related technology. 
         [0017]    In addition, other prior patents to Larsson such as, U.S. Pat. No. 5,984,030, entitled Rock Drilling Tool, Drill Bit and A Method of Transferring Percussive Energy; in addition to the patent to Curington, No. U.S. Pat. No. 3,788,409, also upon Percussion Bits; and the patent to Lundell, U.S. Pat. No. 5,947,215, pertaining to Diamond Enhanced Rock Drill Bit for Percussive Drilling, all disclose relating technology. 
         [0018]    Other related patents or published applications include U.S. Pat. No. 8,051,927, published application No. 2011/0042146, U.S. Pat. No. 5,794,728, U.S. Pat. No. 7,207,402, and published application No. 2009/0260892. These all show similar technology. 
         [0019]    Finally, it was observed during experimentation, that the powder crews, when depositing their explosives within the drilled holes, that there was a very significant reduction of cuttings left in the hole that were drilled with the PCD bits as compared with the carbide bit drilled holes, and this resulted in significantly less time cleaning the holes with a spoon, during the performance of the crews&#39; duties. 
         [0020]    It can be seen that when compared to the prior art style of carbide bits, that the PCD bits have far more advantages, which have been identified during experimentation and testing, at very significant cost reduction advantages for the mine. Production is nearly doubled with the use of the PCD drill bit. The bit cost per foot of hole is reduced, drilling time of the holes is significantly reduced and maintenance costs are minimized. 
       SUMMARY OF THE INVENTION 
       [0021]    This invention contemplates the formation of polycrystalline diamond percussion drill bits, either incorporating PCD chisel contoured inserts, or in combination with PCD conical inserts, and generally used in drill bits for percussion drilling, and can even be used in rotary Tri Cone drill bits, as known. 
         [0022]    These drill bits may be of a double chisel or modified double chisel design, having cutting faces designed to reduce the cost of drilling and to improve drilling penetration rates over the older style tungsten carbide bits. With the PCD type of chisel bit designs, the machine thrust pressure is lowered to the practical range of 10 Bar-20 Bar max, and the machine torque pressure is reduced to 5 Bar-15 Bar max. At these drill settings, the thrust is reduced significantly, even by as much as 70%, and the torque pressure is reduced to around 60%, and the PCD drill bits continue to drill every hole at about the same speed. The PCD bits, whether of the chisel or conical design, stay sharp and show very little or no dulling, even after drilling hundreds of feet of hole into hard rock or high silica ground. The low thrust and torque settings are exclusive for PCD diamond insert percussion drill bits only, to attain maximum penetration rates and maximum bit life. The invention described herein generally relates to small diameter PCD percussion drill bits, that incorporate PCD tipped chisel type designed inserts, and the bits are generally within the range of between about 1⅜″ to 8″ diameters particularly when employed in the circular bits, or even when used in the Tri Cone type of drill bits. 
         [0023]    Three-winging and four-winging bits were tested using the PCD inserts, and were made similar to bits made with tungsten carbide inserts. These PCD bits designs either failed or drilled slower. The two wing double chisel bit design was then tried and the results were outstanding and completely unexpected. The penetration rates achieved were two to four times faster, and the life was 10 to 15 times longer than the carbide bits, and the inserts, during experimentation showed little or no dulling or wear even after drilling over 450 feet of hole in the extremely hard, high silica ground. 
         [0024]    PCD bits with bigger inserts and the larger specific range of radius on the tip of the conical insert was tested several times. The PCD bits made with the larger inserts and larger radius on the tip of the inserts drilled 40% slower than the PCD bits made with a sharper tip. If the tip is too sharp, there is insert failure due to shearing of the insert tip. If the tip is to blunt, it acts like a dull carbide tip. The dimension range is narrow for these PCD inserts of this invention. 
         [0025]    After testing of various dimensions for the PCD inserts, the parameters where established for the inserts and the bit bodies. There is a narrow range for the inserts, and bit body dimensions, and they need to all be balanced with the parameters set for the low thrust and low torque settings on the drill, to attain maximum performance. 
         [0026]    A PCD diamond percussion drill bit means can be used for blast hole drilling and roof bolt drilling. The PCD drill bit is the only drill bit to use extremely low thrust and low torque when drilling very hard, high silica rock. The PCD drill bits have the following advantages:
       1. PCD bits are more productive than carbide bits and show little or no dulling wear on the inserts.   2. PCD bits drill 2-4 times faster than carbide bits.   3. PCD bits last 10-15 times longer than carbide bits.   4. Regarding safety, PCD bits reduce hand injuries, because fewer bit changes are required.   5. The drill steel, striking Bar and coupling life is increased because of the low thrust and torque used when drilling with PCD drill bits.   6. There is reduced maintenance of the drill because of the low thrust and low torque requirements.   7. Bit costs and drilling costs are reduced because of the high footage attained on the PCD percussion drill bits and the fast penetration rate achieved.   8. The application of PCD chisel inserts within the drill bit provides greater penetration and slicing of the earth when such percussion drill bits are used in the drilling of very hard, high silica rock.       
 
         [0035]    The present invention shows how critical dimensions are when drilling with PCD inserts. With the proper dimensions, thrust and torque set to the proper settings, the PCD double chisel and modified double chisel designed bits have proven to exceed the performance of all prior art designs. 
         [0036]    And in the design of PCD inserts, when the inserts are made with a 0.020 to 0.030 inch thick PCD coating of diamond on the tip of the insert, whether it be of the chisel or conical design, the following ranges have been found for the design and manufacture of the percussion drill bit for their most effective applications: 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Range Claimed for 
                 Range  
                 Optimal  
               
               
                   
                 PCD Conical Inserts 
                 Dimensions 
                 Dimensions 
               
               
                   
                   
               
             
             
               
                   
                 OAL of Insert 
                 .490″-.650″ 
                 .543″-.600″ 
               
               
                   
                 Diameter of Insert 
                 .3000″-.4200″ 
                 .3100″ or .3777″ 
               
               
                   
                 Tip Length 
                 .200″-.260″ 
                 .215″-.245″ 
               
               
                   
                 Tip Angle 
                 15.00°-35.00° 
                   15°-30.00° 
               
               
                   
                 Tip Radius 
                 .100″ R-.145″ R 
                 .115″ R-136″ R 
               
               
                   
                 Grip Length 
                 .290″-.420″ 
                 .313″-.400″ 
               
               
                   
                   
               
               
                   
                 Some bits require more than one length of insert for assembly. 
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Range Claimed for 
                 Range  
                 Optimal  
               
               
                   
                 PCD Conical Inserts 
                 Dimensions 
                 Dimensions 
               
               
                   
                   
               
             
             
               
                   
                 OAL of Insert 
                 .600″-.750″ 
                 .685″  
               
               
                   
                 Diameter of Insert 
                 .3900″-.4900″ 
                 .4442″ 
               
               
                   
                 Tip Length 
                 .250″-.350″ 
                 .315″  
               
               
                   
                 Tip Angle 
                 15.00°-35.00° 
                 20.00°-30.00° 
               
               
                   
                 Tip Radius 
                 .120″ R-.155″ R 
                 .136″ R 
               
               
                   
                 Grip Length 
                 .300″-.450″ 
                 .357″-.450″ 
               
               
                   
                   
               
               
                   
                 Some bits require more than one length of insert for assembly. 
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Range Claimed for 
                 Range  
                 Optimal  
               
               
                   
                 PCD Conical Inserts 
                 Dimensions 
                 Dimensions 
               
               
                   
                   
               
             
             
               
                   
                 OAL of Insert 
                 .625″-.785″ 
                 .685″  
               
               
                   
                 Diameter of Insert 
                 .4800″-.5200″ 
                 .5002″ 
               
               
                   
                 Tip Length 
                 .260″-.335″ 
                 .300″-.310″ 
               
               
                   
                 Tip Angle 
                 28.00°-40.00° 
                  .28°-32.00° 
               
               
                   
                 Tip Radius 
                 .135″ R-.170″ R 
                 .150″ R 
               
               
                   
                 Grip Length 
                 .330″-.550″ 
                 .435″-.600″ 
               
               
                   
                   
               
               
                   
                 Some bits require more than one length of insert for assembly. 
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Preferred Ranges Claimed for PCD Chisel Inserts 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 PCD Insert diameter range  
                 .300″ to .750″ 
               
               
                   
                 PCD Insert grip length 
                 .300″ to .600″ 
               
               
                   
                 PCD Insert tip length 
                 .250″ to .360″ 
               
               
                   
                 PCD Tip radius on Chisel Inserts 
                  .04″ to .135″ 
               
               
                   
                 PCD Tip length in a range of 
                 .225″ to .375″ 
               
               
                   
                 PCD Coating thickness on Tip of inserts 
                 .010″ to .035″ 
               
               
                   
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Preferred Further Ranges Claimed for PCD Conical Inserts 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 PCD Insert diameter range  
                 .300″ to .750″ 
               
               
                   
                 PCD Insert grip length 
                 .300″ to .600″ 
               
               
                   
                 PCD Insert tip length 
                 .250″ to .360″ 
               
               
                   
                 PCD Tip radius on Conical Inserts 
                 .115″ to .170″ 
               
               
                   
                 PCD Tip length in a range of 
                 .225″ to .400″ 
               
               
                   
                 PCD Coating thickness on Tip of inserts 
                 .010″ to .035″ 
               
               
                   
                   
               
             
          
         
       
     
         [0037]    A system of drilling, whereby, low machine thrust pressures of 10 Bar up to 25 Bar and low machine torque pressures, of 8 Bar to 20 Bar are used in combination with PCD conical inserts and/or PCD chisel insert drill bits to maximize their performance. 
         [0038]    After considerable research and development, the critical insert and PCD bit dimensions where established for the drill bits as described herein, and then the drill setting parameters where established, as shown, through such experimentation. The drill settings are set far below what a carbide bit can operate effectively at, and this was not obvious to this inventor, in determining what the parameters should be. As previously reviewed, carbide bits in hard, high silica rock need at least 30 Bar of machine thrust pressure, and 30 Bar of machine torque pressure, to drill the first couple of holes. As they dull down, the machine thrust pressure needs to be increased to 50 Bar. The PCD double chisel bit design, to be described herein, required only 8 to 15 Bar of machine torque pressure, and 12 to 15 Bar of machine thrust pressure, to drill with maximum penetration rates and efficiency. Thus, drilling with the PCD insert drill bits takes about 70% less thrust, and 60% less torque than a carbide bit. PCD bits were found to drill two to four times faster than the carbide bits, and are capable of drilling, and they do it with far less thrust and torque. This unique feature of very low thrust and very low torque when drilling with PCD insert percussion drill bits is a significant improvement in this art. Carbide bits cannot perform well at these low settings, and when they get slightly dull, the carbide bits will just slow or stop penetrating the rock at these low settings and will just spin in the drilled hole. These very low drill settings are unique for drilling with the PCD insert bits only. 
         [0039]    As explained in the ranges listed above, the combination of features that are unique to bits made with PCD inserts, and the drill settings are as follows. The PCD insert tip length is significant. The PCD insert tip radius is significant. The PCD insert tip angle is critical. The PCD insert grip length is necessary. The 25 bit body gauge angle in combination with the tip length requires careful analysis when making the PCD insert. For the invention herein, the double chisel design has been found most effective when used on bits from the 1¼″ inch to 2¼″ inch in gauge sizes. The modified double chisel design when used on bits from 2½ inches to 3½ inches gauge sizes is essential for maximum and outstanding performance. The drill settings, as previously explained, for machine torque pressure, should be set and 8 to 15 Bar maximum. The machine thrust pressure setting is set at 12 to 15 Bar maximum, during a drilling performance. 
         [0040]    When the parameters are established for the PCD inserts, in the formation of the bits, during their usage, it has been found that the inserts stay very sharp even after drilling hundreds of feet of hole in high silica, high compressive strength rock, achieving such even at these types of low torque and thrust settings. 
         [0041]    In the inventor&#39;s fifty-four years of designing carbide rotary and percussion drill bits, he has never seen a percussion drill bit made that compares to the percussion PCD double chisel bit design for performance as described herein. The specific body angles, the PCD inserts with very specific lengths, tops, angles and radii, have performed extremely well, and far outperform the carbide inserts which were/are standard in the art. The double chisel bit design requires that a very low torque and very low thrust be used to drill efficiently, and at these low levels of operation, the bits just do not wear out, and have a far more extended life than what can be obtained from a carbide type of bit. Percussion bits made with PCD inserts using the specific insert dimensions, bit bodies, and all the other dimensions identified herein, are believed to be quite unique in the art, and have proven to out perform carbide bits, particularly when used for drilling continuously in hard rock. 
         [0042]    It is, therefore, the principle object of this invention to provide a polycrystalline diamond percussion drill bit, where its inserts are formed within specific ranges of dimensions that have been found, through research and testing, to provide the most effective and efficient percussion bit particularly when used for drilling within high silica or hard rock ground. 
         [0043]    Another object of this invention is to provide a designed bit body for a drill bit in which precisely manufactured and mounted polycrystalline diamond inserts are located to provide a bit for high efficiency usage. 
         [0044]    Another object of this invention is to form and provide drill bits that produce double chisel or modified double chisel cutting effects in usage. 
         [0045]    These and other objects may become more apparent to those skilled in the art upon review of the summary of the invention as provided herein, and upon undertaking a study of the description of its preferred embodiments, in view of the drawings. 
         [0046]    A further object of this invention is to provide the usage and application of PCD inserts, either of the chisel design, or a combination of chisel and conical designed inserts, coated with the polycrystalline diamond at the thickness as previously specified, to enhance and accelerate the drilling operation into hard earth, but at much lower thrust and torque settings than as previously applied. 
         [0047]    To add more specifically to the summarization of the concept of this invention, as an improvement over prior designs, the following parameters for the chisel and conical PCD inserts for percussion drilling can be explained as follows. This application covers the PCD inserts for percussion drill bits in sizes from 1¼″ to 8″ diameter, and which requires low machine thrust pressure and low machine torque pressures in Bar readings. 
         [0048]    The more specific parameters which must be emphasized more fully for the inserts for the PCD conical and chisel type percussion drill bits applications are as follows: 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 PCD Insert diameter range  
                 .300″ to .750″ 
               
               
                   
                 PCD Insert grip length 
                 .300″ to .600″ 
               
               
                   
                 PCD Insert tip length 
                 .250″ to .360″ 
               
               
                   
                 PCD Tip radius on Conical Inserts 
                 .115″ to .170″ 
               
               
                   
                 PCD Tip radius Chisel inserts 
                   .04 to .135″ 
               
               
                   
                 PCD Tip length in a range of 
                 .225″ to .400″ 
               
               
                   
                 PCD Coating thickness on Tip of inserts 
                 .010″ to .035″ 
               
               
                   
                   
               
             
          
         
       
     
         [0049]    PCD inserts may very in size, depending upon the gauged diameter of the PCD drill bit being made. Any combination of lengths may be used in a single bit as may be required. 
         [0050]    Any carbide bit designed today, can be used and the carbide inserts replaced with a PCD conical insert, but the usage of the PCD chisel type inserts require a design unique to the industry. They require specific angular settings for each insert, especially in large diameter drill bits, of the 3½″ to 8″ size in diameter. 
         [0051]    All bits incorporating PCD chisel and conical inserts require a low machine thrust pressure and a low torque machine pressure to function properly and effectively. 
         [0052]    PCD flat chisel type inserts and PCD conical inserts have been used in rotary drill bits for several years, where there is no percussion impacting the inserts of the drill bit. Only heavy downward pressure and rotation are applied to the PCD inserts in a Tri Cone, gear type, type drill bits or the winged PCD flat insert drag bits, for cutting the rock. 
         [0053]    This invention utilizes conical shaped inserts with a PCD coating on the top, on a cylindrical body, or a PCD chisel shaped top on a cylindrical insert for percussion drilling. 
         [0054]    The design of percussion drill bits using chisel type inserts by the invention, is unique to the percussion drill bit industry. Only since it was discovered, that PCD percussion drill bits require a low machine thrust pressure and a low machine torque pressure, has it been possible, to use PCD conical and chisel type inserts for percussion drilling. 
         [0055]    The design of the chisel PCD inserts may be used in most bit designs to replace the carbide inserts currently used, to increase bit life, to increase penetration rates and reduce down time changing bits. However, the PCD chisel inserts should be placed, so that they are rotary plowing or slicing and cutting the rock as well as cutting the rock with the hammer impacts. 
         [0056]    From early testing of the chisel bit design, it was obvious that the penetration rate is nearly twice as fast as a carbide bit of similar size. The outer gauge inserts of carbide, develop a negative clearance angle on the insert, and require the thrust and torque to be increased to the maximum settings on the drill as they dull down. 
         [0057]    The PCD bits start with low thrust and low torque settings and rarely need to be changed during the life of the PCD drill bit as the diamond table does not dull down and pinch in the hole like a carbide bit. The penetration rate over the life of the PCD insert bits is nearly constant, whereas, the penetration rate of the carbide insert bits start to slow immediately upon drilling hard rock, and requires the thrust and torque to be increased as the carbide bit dulls down. Testing of penetration rates for a carbide bit started at 2.15 min/hole at 30 Bar thrust and torque and fell to 6.45 min/hole, at 50 Bar thrust and 40 Bar torque, by the time seven holes were drilled in hard, high silica ground. 
         [0058]    In contrast, the PCD bits drilled at a rate of 1 minute 27 seconds to 1 minute 58 seconds at 15 Bar thrust and 10 Bar torque over 95 holes. The machine thrust and torque pressures never needed to be increased for maximum drilling performance with PCD insert drill bits. 
         [0059]    Holes drilled with PCD insert bits, are cleaner of cuttings remaining in the hole after drilling and reduces the time spooning the debris out of the drilled holes before loading with prills. 
         [0060]    Mine production can be nearly doubled by just changing from carbide drill bits to PCD drill bits, and using the low parameters for machine torque pressure, 8 Bar to 20 Bar and machine thrust pressure, 10 Bar to 25 Bar as defined by testing. If high thrust machine pressure, 30 Bar-50 Bar, and high machine torque pressure, 30-50 Bar are used with PCD insert drill bits. Insert shearing is likely to occur, resulting in loss of an expensive drill bit. Holes drilled with high thrust and torque pressures, will retain more cuttings in the hole and require more time spooning cuttings from the hole before loading can be done. 
         [0061]    The combination drill bit using the PCD chisel type insets and PCD conical inserts increases the penetration rates substantially and requires 50% to 70% less machine thrust pressure and machine torque pressure than carbide drill bits. 
         [0062]    The action of the two PCD insert types, provide yet, another and faster way to drill. The conical inserts fracture the rock with each blow of the drill hammer. The wide PCD chisel insert also fractures the rock but the plowing action of the PCD chisel inserts, remove more of the rock kerf from the hole, with each impact of the drill hammer. When these PCD chisel inserts, are set an angle to attain a slicing action, the chisel inserts are not perpendicular to the direction of rotation but set an angle, in a range of 0° to 40° along the angular arc of rotation. They are set at an angle to the arc of rotation. 
         [0063]    The PCD inserts can be set as above, then the chisel cutting edge is skewed or pivoted to 0° to 12°, to the right to provide a slicing action. This skew reduces the torque pressure on the chisel type insert and helps to prevent insert breakage. 
         [0064]    All conical or chisel PCD drill bits must have large flutes and large air holes, 2-5 holes, to allow the cutting to be rapidly flushed from the face of the drill bit so that they are not pulverized before being flushed from the hole and the face of the bit. 
         [0065]    An air mist system or 100% water may be used for cooling the PCD inserts and flushing of the cuttings from the drilled hole. Holes in each bit body, can vary in size from 3/16 to 3/ 4″. The number of holes will vary from two (2) to five (5) flushing holes per PCD bit. Always use the largest holes possible to assure maximum flushing of the cuttings from the drilled hole. 
         [0066]    Bits with a full round face are not as effective in drilling as the bits designed with an X face because they tend to have less clearance for the cut rock to flush from the face of the drill bit and re-drill or pulverize the cuttings before they are flushed from the hole. All PCD bit designs will drill, but to attain maximum penetration rate possible, the X design was the fastest in the testing program. All PCD bits, utilizing PCD conical and chisel type inserts, only use low thrust and low torque pressures, so as to prevent the PCD inserts from breakage. 
         [0067]    To provide a further explanation relating to the improvements made in the concept of this invention, which adds the addition of the PCD chisel type design, reference must be made to the prior application of the applicant, Ser. No. 13/987,893, which is now U.S. Pat. No. ______. That application, for which this current application claims priority as a continuation-in-part, is intended to be fully incorporated herein by reference into this application, and to add to its disclosure of the technology involved. 
         [0068]    For example, in referring to the drawings, and in particular  FIG. 9 , therein is shown a part of a bit body that is applied to the drill shaft for the drilling system, and its discloses the general parameters for the shape of the cutting face for the bit, when it is manufactured and assembled. As can be seen, the body  1  includes its cutting face  2 , and has a beveled angle for the cutting face, as noted at  3 , which surrounds the circumference of the said cutting face. The various parameters for the body angle, the gauged diameter, and the center face for the cutting face, are shown and described herein, and have previously been summarized. 
         [0069]      FIG. 10  shows an example of a PCD insert  4 , of the conical type, and the inserts, for this embodiment, include a gripping portion  5 , which is generally formed of tunston carbide, and the parameters for its dimension can be seen and summarized and as noted herein. The formed tip  6  for the insert, and the concept of the usage of conical inserts in this invention, in combination with the chisel design, is the high pressure formation and application of the polycrystalline diamond structure to the insert tip, as will be noted. The insert tip is applied by high pressure and heat to the tunston carbide tip portion of the insert, and is formed to very specific radius, at the tip, and has specific tip angles, in addition to length, all as previously summarized when identifying the ranges for the formation of the conical inserts, and their tip length, tip angles, tip radius, and grip length. The overall diameters for the conical inserts where also reviewed, as previously summarized. 
         [0070]      FIG. 11  shows an entire bit body  7 , and also discloses the cutting face  8 , in addition to the concave clearance portions  9 , for the shown bit. Internally of the body is a cavity  10 , that communicates with a reduced diameter aperture  11 , which conveys the cleaning fluids, such as water, to the forward portion of the bit, and exists under pressure from select apertures, such as the side openings  12 , as noted within the side of the shown bit. There are actually a pair of such openings formed in the bit body, for use for injection of fluids, to flush away the drilled earth. This allows for the discharge of fluid, such as water, under pressure, to help clean out the cutting debris, formed during a drilling operation, and forces it to flow upwardly along the concaved cavities  9 , and up the sides of the drill shaft, for discharge from the hole being drilled, during the drilling operation. While the beveled face for the bit is shown at 28°, it generally will be between 25° to 32° of incline. 
         [0071]    The actual configuration of the conical style of insert, as previously summarized in  FIG. 10 , can also be seen in  FIGS. 12 a  and 12 b   , in addition to  FIG. 13 , that shows the insert body, with the polycrystalline applied to its tip, for use in combination with the chisel type PCD bits, as to be described hereinafter within this application. 
         [0072]    This provides a summarization of the concept of this invention, and the improvements made to percussion drilling, through the usage and application of a combination of chisel type PCD inserts for a drill bit body, with PCD conical drill bits, or the application of the chisel type drill bits alone. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0073]    In referring to the drawings, 
           [0074]      FIG. 1 a    through  FIG. 1 d    shows, respectively, a side view, front view, and top view for the multi angle chisel design for a PCD insert; 
           [0075]      FIG. 1 e    shows a side view of the insert, disclosing specific dimensions to its various angles upon its cutting tip; 
           [0076]      FIG. 1 f    provides a transverse sectional view taken through the chisel bit along lines f-f of  FIG. 1   e;    
           [0077]      FIG. 2 a    shows a top view of the application of a pair of PCD chisel inserts applied in a negative slicing angle within a percussion drill bit; 
           [0078]      FIG. 2 b    provides a top view of the application of a pair of PCD chisel inserts into a percussion drill bit and arranged at a 0° angle to provide a plowing type of cutting of earth during usage. 
           [0079]      FIG. 2 c    provides a top view of a pair of PCD inserts applied to a percussion drill bit and arranged at a positive slicing angle of approximately 10° when used in percussion drilling; 
           [0080]      FIG. 2 d    provides a front view of a percussion drill bit having a pair of the PCD chisel inserts arranged along the double taper of the top of the shown drill bit; 
           [0081]      FIG. 3  provides a top view of a drill bit incorporating a plurality of PCD chisel inserts primarily arranged in the plowing mode, with a single skewed insert provided for functioning in a slicing mode during percussion drilling; 
           [0082]      FIG. 4 a    shows a percussion drill bit incorporating a series of PCD conical inserts; 
           [0083]      FIG. 4 b    shows a top view of a percussion drill bit incorporating a series of PCD chisel type inserts; 
           [0084]      FIG. 4 c    provides a side view of the percussion drill bit disclosed in  FIG. 4   b;    
           [0085]      FIG. 5  provided a top view of a percussion drill bit having a frontal flat face and an integral beveled face incorporating a series of the PCD conical type inserts; 
           [0086]      FIG. 6  is a top view of a percussion drill bit incorporating a series of the PCD chisel type inserts, select of most of said inserts being incorporated within the bit and arranged in a slicing mode; 
           [0087]      FIG. 7  is a top plan view of a percussion drill bit having a frontal flat face and an integral beveled face extending outwardly therefrom, and incorporating a series of PCD chisel inserts primarily arranged for providing the slicing mode for percussion drilling; 
           [0088]      FIG. 8  provides a top view of a percussion drill bit having a frontal flat face and an integral beveled face extending outwardly therefrom, and incorporating a series of combinations of PCD chisel inserts and PCD conical type inserts in its design; 
           [0089]      FIG. 9 , as previously reviewed, is a partial side view of a bit body showing its various parameters; 
           [0090]      FIG. 10  provides a side view of an insert, of the polycrystalline diamond and conical design, for application to the front surface or cutting face of the bit body, as of  FIGS. 5 and 8 ; 
           [0091]      FIG. 11  shows a complete side view of a bit body disclosing its cutting face at one end, having both a frontal flat face and beveled face extending outwardly therefrom, and showing at least one of the discharged ports for the application of cleaning fluid, or water, used to flush out the drilled hole during percussion drilling; 
           [0092]      FIG. 12 a    provides a top view of a conical insert for a percussion drill bit; 
           [0093]      FIG. 12 b    shows a side view, partially cut away, of a conical insert having a polycrystalline diamond coating provided upon its upper surface; and 
           [0094]      FIG. 13  shows a further side view, and the various dimensions, for the complete polycrystalline conical insert for a percussion drill bit, as used in this invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0095]    This invention provides an advancement to the art of percussion drilling, and adds to the concept of utilizing polycrystalline diamond percussion drill bits, where the various inserts are coated with a layer of PCD, in order to provide a far more durable cutting face for the bit, when it is used in percussion drilling within very hard soil, such as hard rock, or high silica ground. More specifically, this invention includes the application of inserts, into percussion drill bits, of a chisel type of design, which are polycrystalline diamond coated, and can be used in combination with PCD carbide conical tips, or a plurality of the chisel type of inserts, when applied to the drill bit, that can be used independently. In any event, in the use of the chisel type PCD inserts, whether alone, or in combination with the conical PCD drill bits, the percussion drilling operation is far more efficient, much more durable for long lasting life of the bits, and in addition, can be operated at much lower torque and thrust pressures, than when the standard type of carbide inserts are used in drill bits, for related drilling operations. 
         [0096]    More specifically, in referring to  FIGS. 1 a    through  1   d,  a chisel type of PCD insert  20 , can be seen. The insert includes the gripping portion  21 , in its lower segment, and has an upper contoured tip  22  which, as can be seen in  FIG. 1 b   , has a pair of inclined surfaces, one as shown at  23 , as noted in  FIG. 1   c.  There are a pair of such inclined surfaces, as at  23  and  24 , which incline upwardly, towards an upper widened vertex, as can be noted at  25 , and which generally extends from side to side across the top of the insert, as seen in  FIG. 1   c.  At the bottom  26  of the gripping portion  21 , there is a slight bevel or radius, as noted, and this is to facilitate the insertion of the inserts into the drill bit, when the bit is being assembled, for use for a drilling operation. The various parameters for the PCD chisel and conical insert, when used in the form of a chisel insert, as at  20 , in the preferred embodiments, can have the following range of dimensions: 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 Insert Parameters for PCD Conical and Chisel Type Percussion  
               
               
                 Drill Bit Applications 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 PCD Insert diameter range  
                 .300″ to .750″ 
               
               
                 PCD Insert grip length 
                 .300″ to .600″ 
               
               
                 PCD Insert tip length 
                 .250″ to .360″ 
               
               
                 PCD Tip radius range Conical Inserts 
                 .125″ to .170″ 
               
               
                 PCD Tip radius range Chisel Inserts 
                  .04″ to .135″ 
               
               
                 PCD tip length in a range of 
                 .225″ to .375″ 
               
               
                 PCD Coating thickness on Tip of Inserts. 
                 .010″ to .035″ 
               
               
                   
               
             
          
         
       
     
         [0097]    A typical example of the dimensions for the specifically applied chisel form of insert, can be seen in  FIGS. 1 e    and  1   f.  As can be noted, it includes its base portion  21 , its top portion  22 , and it is this top portion that is coated with the polycrystalline diamond material, and generally the coating thickness is to that range as previously explained, approximately 0.010″ to 0.035″, in its application. And, in this embodiment, the top edge  25  extends transversely across the width of the insert, and it may have slightly inclined side edges, as at  27  and  28 , in order to eliminate any sharpened edges that may possibly wear quicker during usage of the drill bit in which these chisel inserts locate, for percussion drilling usage. 
         [0098]    In the application of these PCD chisel inserts, within drill bits, their primary usage can be noted in  FIGS. 2 a  through 2 d   . As noted, as in  FIG. 2 a   , the drill bit  29  contains a pair of PCD chisel inserts, as noted at  30  and  31 . In this particular instance, the upper ridge or vertex of the inserts, as at  25 , are arranged on an angle with respect to the radial dimension of the insert, and in this instance, the radial dimension would be the perpendicular radius to the outer arc of rotation of the drill bit, and as noted, the chisel inserts are arranged at a negative slicing angle of approximately 10°, off the radius, as shown. This means when the drill bit is rotated in the clockwise direction, the slicing of the earth due to the percussion impacting of the drill bit into the earth will generally force the debris towards the outer edge of the bit, as can be understood. 
         [0099]    On the other hand, as can be seen in  FIG. 2 c   , the chisel inserts are arranged, in this embodiment, in a positive 10° angle, off of the radius of the bit, and therefore furnishes a positive slicing action into the earth, when the drill bit is impacted and rotated in the clockwise direction, during a percussion drilling operation, and therefor, the chisel upper surface  25  has a tendency to not only ground into the hard rock, but as it does so, urges any debris inwardly, when the drill bit is continued in its rotation in that clockwise direction, during percussion drilling operations. 
         [0100]    This is all distinguish from the use of the chisel inserts, as noted in  FIG. 2 b   , the upper edges of the chisel inserts are arranged along the radius of the drill bit  29  as can be seen. Thus, there is 0° angle between the installed chisel inserts, within the bit body, and thus, the chisel inserts simply plow the surface of the ground being drilled, does not have a tendency to achieve any slicing of the earth, or its movement, other than simply through a plowing action when the bit body is still rotated in its clockwise direction. 
         [0101]      FIG. 2 d    shows an example of the bit body  32  of one design, where the upper surface of the bit body is formed of approximately three surfaces, a center flat surface  33  and a pair of integral inclined surfaces  34  and  35  and into which the chisel type of inserts  30  and  31  are inserted and installed within the drill bit  32 . 
         [0102]    Once again, all of these various chisel inserts, regardless to what angle they are applied within their drill bit body, are coated, upon their tip length, as previously summarized at 6, with the polycrystalline diamond composition, to add to the hardness of the drill bit, through its usage of PCD inserts, of the types as previously described, whether they be of the chisel type, or the conical form of insert. 
         [0103]    An example of the application of the chisel form of PCD inserts to the drill bits, can be noted in  FIG. 3 . This is an example of an array of chisel type inserts applied to the frontal surface  36  of the shown drill bit. As noted, a series of the inserts that locate along the outer perimeter of the drill bit can be seen at  37  through  40 . As noted, these particular inserts are arranged at approximately a perpendicular angle to the arc of rotation of the bit, and pairs of them, as  37  and  39 , and  38  and  40 , are arranged linearly, as noted at  41  and  42 , and the inserts are arranged in a plowing mode, rather than slicing mode, when used in a drilling operation. The plowing mode means that the upper transverse edge, one as shown at  43 , is arranged 90° from the direction of rotation of the drill bit, during its application and usage. Thus, the edge of the insert does not slice the hardened ground, but rather, impacts it due to the percussion drilling, and then simply plows the debris forwardly, in order to achieve further cutting of the rock, in its pushing forwardly, during the rotation of the drill bit. It has been found that the PCD chisel insert, when they angled at about a 30° angle, apart from the vertical, as noted, or approximately at that perpendicular angle with respect to the arc of rotation, and thus are further arranged approximately 60° apart from each other, as noted, from the direction of rotation. 
         [0104]    As can further be noted, an additional PCD chisel insert  44  is provided, and it is arranged at an angle of approximately 15°, from the perpendicular, in order to reduce the torque pressure on the insert and have the insert cutting action in a slicing type of mode, for drilling. 
         [0105]      FIG. 4 a    shows another embodiment for a PCD drill bit  45 , in this particular instance, being 5 inserts located strategically around the surface of the bit, both on its frontal flat face  46 , and its beveled peripheral edges, as at  47 , and includes the PCD conical type of insert design, as noted at  48 . There is an additional conical insert  49  provided upon the frontal flat face of the drill bit, while the remaining conical inserts locate upon its beveled edges. There is also at least one fluid flush hole  50  through which the cleansing fluid, such as water under pressure, discharges into the vicinity of the face of the drill bit, during a percussion drilling operation, in order to remove the fractured debris, in the manner as previously explained. 
         [0106]    It might be summarized, once again, at this time, that the various types of PCD conical inserts provided within the frontal face of the drill bit, in practical application, may have the following range of dimensions, in their structure. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 Insert Parameters for PCD Conical and Chisel Type Percussion  
               
               
                 Drill Bit Applications 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 PCD Insert Diameter range  
                 .300″ to .750″ 
               
               
                 PCD Insert grip length 
                 .300″ to .600″ 
               
               
                 PCD Insert tip length 
                 .250″ to .360″ 
               
               
                 PCD Tip radius Range Conical Inserts 
                 .125″ to .170″ 
               
               
                 PCD Tip radius Range Chisel Inserts 
                  .04″ to .135″ 
               
               
                 PCD tip length in a range of 
                 .225″ to .375″ 
               
               
                 PCD Coating thickness on Tip of Inserts 
                 .010″ to .035″ 
               
               
                   
               
             
          
         
       
     
         [0107]      FIG. 4 b    shows a related type of percussion drill bit  51 , but in this particular instance, it contains a plurality of the chisel type PCD inserts, as noted at  52 . These inserts are generally arranged and provided along the outer beveled surface  53 , and generally are set in the plowing mode, since the angle of their upper cutting edges, as at  54 , are generally arranged at the perpendicular to the arc of rotation of the drill bit, during usage, and are a further arranged in alignment with the radius from the center of the drill bit, as can be noted. There is a further chisel PCD insert  55  that is provided within the upper flattened face  56  of the drill bit, and this particular insert, and its upper transverse cutting edge  57  will be arranged at various angles with respect to the perpendicular to the arc of rotation of the bit, in order to place this particular insert into a plowing mode. Hence, it has been found desirable to arrange this particular insert, at an angular disposition with respect to said perpendicular, between about 0°, which would be in a plowing mode, and up to approximately 45°, which would furnish the ultimate slicing mode for this particular insert, when applied within the percussion drill bit, during a drilling operation. The aperture  58 , once again, is provided for delivering cleansing fluid such as water under pressure, to the face of the drill bit, during a percussion drilling operation. 
         [0108]      FIG. 4 c    shows a side view of the chisel PCD inserts, such as  52 , provided within the beveled outer surface of the drill bit, and the insert  55  that is provided extending from the frontal flat face  56 , of the shown bit body  59 . 
         [0109]    It might be stated at this time that the usage of the various inserts in the drill bits, such as shown in  FIGS. 4 a   , and subsequently in  FIGS. 5 and 6 , all have select either conical or chisel type of inserts provided upon the frontal flat face of the shown drill bits. And, there are also either conical or chisel inserts that are provided upon the outer beveled surfaces of the front face of the drill bits, as can be noted. In effect, when these types of bits, with their shown inserts, are applied, at these angular installations, those inserts provided upon the upper flat face of the bit function in a drilling action to initiate the cutting of the pilot hole at the center of the drilled hole, and then the outer inserts applied to the beveled surfaces of the bits function to ream the rock, into a refined drilled hole, during usage of these PCD percussion drill bits. It is believed this occurs because the inserts in the frontal flat face of the drill bits are actually higher or extend further upwardly from the inserts provided upon the beveled faces, and therefore, one does function a means for drilling the pilot hole, while the outer gauge inserts function for reaming the rock to the piloted center cut. 
         [0110]      FIG. 5  show the application of a series of PCD conical inserts  60  and  61  applied to the beveled portion  62  of the drill bit, and also to the frontal flat face  63 , respectively. It is to be noted that the conical inserts generally have slightly different dimensions from the center point  64  of the shown bit, in order to lesson tracking of the cutting achieved by the various inserts, during a percussion drilling operation. 
         [0111]      FIG. 6  provides a top view of the percussion drill bit  64  having a series of PCD chisel inserts  65  and  66  provided, respectively, upon the outer beveled surface  67  and the frontal flat face  68  of the shown drill bit, as previously reviewed. As can be noted, the transverse upper cutting edges, as at  69 , are slightly angulated, at a small degree, off of the perpendicular from the arc of rotation of the drill bit, in order to initiate the functioning of the insert into a slight slicing mode, particular with respect to those inserts  65  provided upon the outer beveled surface. But, the transverse upper cutting edges  70  of those inserts applied to the frontal flat face  68  of the bit are arranged at much greater angles, approximately 30°, as shown, in order to provide full slicing through the application of the bit when impacting upon the hardened earth, during performance of a percussion drilling operation. 
         [0112]      FIG. 7  shows the usage of a plurality of the PCD chisel type inserts, as at  71 , applied to the outer beveled surface  72  of the drill bit  73 . And, most of these inserts, and more specifically their upper transverse cutting edges  74 , are arranged in a slicing mode, being offset a few degrees from the perpendicular to the arc of rotation of the drill bit, during its usage. As can be seen, most of these upper edges, as noted at  75 , are arranged a few degrees, approximately 10°, off of the perpendicular to the arc of rotation of the bit, during usage. In this manner, these inserts function in a slight slicing mode when impacting the hardened earth during a percussion drilling operation. They push the debris outwardly of the shown bit. As can also be seen, for the flat frontal face  76  for the drill bit, the PCD chisel type inserts  77 , are located within the bit body, at various locations, and at more significant angles from the perpendicular to the arc of rotation, of the drill bit, when used. For example, it can be seen that the transverse upper cutting edge  78  for one of the inserts  77  is at an approximate 30° angle from the perpendicular to the arc of rotation, as are the transverse cutting edges  79  and  80  for the shown inserts, which are clearly deployed in the surface of the drill bit in the slicing mode of usage. And, as can be noted, there are just no vertical planes of symmetry that pass through the central axis of the bit body, with respect to each of these applied PCD chisel type inserts, particularly those that are arranged within the frontal flat face  76 , of the shown drill bit. Furthermore, as can be noted, many of the inserts  77  installed within the flat face  76  of the drill bit are at a different radii from the center  81  of the bit body, and therefore, avoids tracking of any of these inserts relative to the other during performance of a percussion drilling operation. In other words, each insert does its own slicing of the ground, independently of the other inserts, in order to greatly enhance the efficiency of the drilling operation, when performed. In addition, in order to maximize flushing of any cuttings from the drilled earth, there are a series of apertures  82  for delivering water under pressure to the front surface of the drill bit, during a percussion drilling operation. 
         [0113]      FIG. 8  discloses a percussion drill bit  83  where a combination of PCD chisel type inserts, as at  84 , are used in combination with a series of PCD conical inserts  85 , as can be noted. This type of drill bit, containing this many inserts, is generally structured in the four inch through 8 inch percussion type, and down the hole hammer drill bit, such as  83 , as noted. Any combination of the conical and chisel designed PCD inserts are employed, and it is believed that this is the first time that such a combination has been structured. A similar type of relationship of a combination of chisel type inserts  86 , and a series of PCD conical type inserts  87  are also applied to the frontal flat face  88  of the shown drill bit. You should note that most if not all of the transverse cutting edges  89  are arranged in a slicing mode, generally between slightly more than 0°, and up to 45°, with respect to the perpendicular from the arc of rotation of the drill bit, when employed. This provides that slicing type of cutting of the harden earth, during usage of the percussion drill bit, when performing a drilling operation. You should also note that many of the various inserts, whether of the PCD chisel type, or the PCD conical type, are arranged at differing distances along the radii from the center of the drill bit, in order to, once again, avoid tracking of one bit in its cutting function from overlapping the operations of another insert, during percussion drilling. And, the water apertures  90  are provided for flushing of the debris during a drilling function. The asymmetrical design of the location of the various applied inserts, with respect to the center axis of the bit, is provided, in order to enhance the efficiency of the drilling operation. A drill bit, of this design, is designed to drill fast, and clear the hole of cuttings, than has heretofore been designed. 
         [0114]    Variations or modifications to the subject matter of this invention may occur to those skilled in the art upon review of the disclosure as provided herein. Such changes or variations, if within the spirit of this invention, are intended to be encompassed within the scope of any claims issuing in this patent. The description of the invention as set forth herein, and its depicted in the drawings, are primarily set forth for illustrative purposes only.