Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B51/00—Tools for drilling machines
  • B23B51/02—Twist drills
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B51/00—Tools for drilling machines
  • B23B51/06—Drills with lubricating or cooling equipment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
  • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
  • B23P15/28—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass cutting tools
  • B23P15/32—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass cutting tools twist-drills
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2251/00—Details of tools for drilling machines
  • B23B2251/04—Angles, e.g. cutting angles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2251/00—Details of tools for drilling machines
  • B23B2251/04—Angles, e.g. cutting angles
  • B23B2251/043—Helix angles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2251/00—Details of tools for drilling machines
  • B23B2251/40—Flutes, i.e. chip conveying grooves
  • B23B2251/408—Spiral grooves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2251/00—Details of tools for drilling machines
  • B23B2251/44—Margins, i.e. the narrow portion of the land which is not cut away to provide clearance on the circumferential surface

Definitions

• the present invention relates to a drill, and more particularly, to a twist drill for drilling a hole, which includes one or more spiral flutes, and one or more lands formed between the flutes, respectively, thereby bordering the flutes.
• a drill is a tool generally used so as to drill a hole or to cut a groove in a workpiece of metal or wood.
• twist drills are most frequently used.
• the twist drills include one or more spiral flutes (grooves for taking out chips), and one or more lands formed between the flutes, respectively, as mentioned above.
• the above-mentioned method of supplying cutting oil or the like to the point of the drill from the outside has several disadvantages. For example, if it is desired to form a hole in the workpiece by using a drill and the hole has a depth which is four or more times larger than the diameter of the drill, the cutting oil cannot be sufficiently supplied to the point of the drill. Consequently, the point of the drill will be overheated.
• such an oil hole drill is formed with one or more spiral oil holes through the drill body so as to allow cutting oil to be supplied to the point of the drill from the outside.
• the oil hole extends from the trailing end area to the point of such a drill through the drill body, wherein the trailing end area means a part to be grasped by a holder or a drill chuck of a drilling machine.
• the cutting oil is supplied from the trailing end area and exits from the point of the drill, thereby preventing the point of drill from being overheated.
• the cutting oil exiting from the point of the drill is discharged to the outside along the flutes of the drill, thereby enabling chips to be more smoothly discharged from a hole formed in a workpiece while the hole is being drilled.
• a cylindrical steel rod is prepared through sintering, wherein one or more oil holes are formed through the cylindrical steel rod while the cylindrical steel rod is sintered.
• each of the oil holes is formed in a spiral shape with a predetermined lead angle corresponding to the twist angle of the drill and extends through the entire length of the cylindrical steel rod.
• one or more spiral flutes are formed through grinding, wherein each of the spiral flutes has a predetermined lead angle or flute angle.
• the cylindrical steel rod has already formed with the spiral oil holes extending through the steel rod and having a predetermined lead angle
• the oil holes may burst while the flutes are formed unless the spiral flutes are formed with the same lead angle as the spiral oil holes and substantially in parallel to the oil holes. As such, expensive steel rods may be thrown away.
• the lead angle or flute angle of the flutes of the oil hole drill is determined depending on the lead angle of the oil holes, wherein the lead angle of the oil holes is determined when the oil holes are formed through the cylindrical steel rod while sintering the cylindrical steel rod.
• the oil hole drill has a disadvantage in that the lead angle of flutes should be fixed.
• existing oil hole drills typically have a fixed flute angle (lead angle) of 28°or 30°.
• the oil holes are formed in a cylindrical rod material used for fabricating such an oil hole drill while sintering the rod material, the rod material used for fabricating such an oil hole drill is considerably expensive as compared to a material used for fabricating a conventional drill free of oil holes four to ten times. In other words, the price of such a drill is considerably increased.
• the oil holes are formed through the drill body, it is difficult to form such oil holes if a drill has a small diameter (for example, D3 or less). Further, even if oil holes are formed, the rigidity of the drill itself is very poor due to the oil holes. As a result, smooth cutting action cannot be achieved and the drill is easy to fracture. Accordingly, a small diameter drill is not formed with oil holes, whereby cutting oil is directly supplied to the point thereof from the outside so as to prevent the drill from being overheated. However, the above-mentioned problems still occur in such a small diameter drill.
• burrs may be generated on the wall or in the vicinity of a drilled hole in the workpiece.
• a drill is subject to high cutting load at the point and lands thereof. If the drill is repeatedly subject to such high cutting load as the drill is continuously used for forming holes in a workpiece, the performance of the drill is deteriorated, and burrs are consequently generated on the wall or in the vicinity of any hole drilled by the drill.
• burrs are generated as the vicinity of a drilled hole is plastically deformed and pushed due to the feeding of the drill, and that the rotating speed, the feed, and the tip angle of the drill affect the generation of burrs. Furthermore, the performance of the drill deteriorated due to the overheating also affects the generation of burrs as described above. Due to the burrs, it is typically performed a separate process, i.e., a finishing process for removing the burrs. In particular, if such an intentional burr removal process is not perfectly performed, a critical defect may occur in the workpiece due to the remaining burrs.
• An object of the present invention is to provide a drill capable of achieving smooth cooling, chip discharging, and lubrication effects, even if no oil hole is provided.
• Another object of the present invention is to provide a drill, which can provide the same effects as an oil hole drill, and the flute angle of which can be variously determined as desired because no oil hole may be provided.
• Still another object of the present invention is to provide a drill capable of providing a desired effect even if it has a diameter which is too small for oil holes to be formed through the body of the drill.
• Another object of the present invention is to provide a drill, which has a structure allowing fluid such as cutting oil to be stably supplied to the point of the drill.
• Another object of the present invention is to provide a drill, which has a simple structure allowing cutting oil to be stably supplied to the point of the drill, thereby decreasing heat to be applied to the point, so that it is possible to prevent the occurrence of burrs on the wall or in the vicinity of a drilled hole of a workpiece, even if no oil hole is provided.
• Still yet another object of the present invention is to provide a drill capable of reducing cutting load to be applied to the drill, in particular to the lands of the drill during a drilling operation, thereby preventing the deterioration of drill performance.
• a drill including: a point formed with cutting edges; one or more spiral flutes; and one or more lands formed between the spiral flutes, respectively, thereby bordering the flutes, wherein a groove with a predetermined depth is formed on the top surface of each of the lands, so that fluid can be supplied to the point of the drill along the groove.
• a method of manufacturing a drill including steps of: providing a cylindrical rod having flute lines for forming one or more flutes with a lead angle suitable for a desired use; forming one or more flutes along the flute lines; forming a groove with a predetermined depth on the top surface of each land, one or more lands being produced as the flutes are formed; and performing a thinning operation for reducing the diameter of one end of the cylindrical rod so as to form cutting edges.
• an oil groove is formed on each of one or more lands of a drill, so that the cutting oil is smoothly supplied to the point of the drill. Accordingly, even if no oil hole is formed through the drill body through a very complicated and difficult operation such as sintering, the drill can provide the same effects as an oil hole drill. In addition, if no oil hole is formed through the drill body, it is possible to freely design a flute angle suitable for a desired use. As a result, the present invention can be applied regardless of a drill diameter.
• FIG. 1 is a perspective view schematically showing an entire structure of a drill according to an embodiment of the present invention
• FIG. 2 shows a point of a conventional drill and a point of a drill according to an embodiment of the present invention
• FIG. 3 is a partially enlarged perspective view showing a detailed structure of an oil groove. Best Mode for Carrying Out the Invention
• FIGs. 1 to 3 show a drill 100 according to an embodiment of the present invention.
• the drill 100 comprises a point 120, a main body 140, and a mounting part 160.
• the point 120 is formed with one or more cutting edges 122.
• One or more spiral flutes 142 are formed over the entire main body 140 from the point 120.
• One or more lands 144 are formed between the flutes 142, respectively, so that the lands 144 border the flutes 140, respectively.
• the mounting part 160 is formed at the end of the drill 100 opposite to the point, wherein the mounting part 160 has a shank S and a tang T for fitting the drill to a holder (drill chuck) of a drilling machine.
• each of the lands 144 of the inventive drill 100 has a top surface which is not flat unlike a conventional drill.
• each of the lands is formed with an oil groove 146 with a predetermined depth on the top surface thereof, so that the grooves guide fluid such as cutting oil to the point 120 along the main body 140 of the drill 100.
• the oil grooves 146 are formed along the outer surfaces of the lands 144, respectively, so that fluid such as cutting oil can be supplied to the point along the oil grooves 146 during the drilling process, thereby lubricating and cooling the drill.
• the fluid supplied to the point of the drill is smoothly discharged to the outside along the oil grooves again.
• the cutting oil is smoothly supplied to the point along the oil grooves formed on the top surface of each land of the drill. As a result, even if a depth of a drilled hole is deepened as the drilling operation is continuously performed, the cutting oil can be stably supplied to the point of the drill along the oil grooves 146.
• each of the lands 144 consists of an oil groove 146 and an edge area e, wherein the edge area e gets in touch with the wall of a hole while the hole is being drilled in the workpiece.
• the lands entirely get in touch with the wall of a hole formed through a workpiece.
• the top surfaces of the lands 146 get in touch with the wall of the hole while the hole is being formed, whereby high cutting load is applied to the lands.
• the drill performance is deteriorated as the drill is repeatedly used in drilling.
• not the entire lands 146 but the edge areas e get in touch with the wall of a hole while the hole is being formed through the workpiece, whereby the contact area can be substantially reduced.
• the cutting load applied to the whole drill edges can be lowered, thereby suppressing the deterioration of the drill performance and remarkably increasing the durability of the drill.
• the flute angle directly affects on the cutting performance and chip discharge ability of a drill.
• the flute angle increases, the cutting performance of a drill is enhanced while the chip discharge ability is deteriorated. Therefore, if a workpiece is formed from a hard material and thus high cutting performance is required so as to process the workpiece, a drill with a large flute angle is used. However, if a workpiece is formed from a soft material and thus high cutting performance is not required, a drill with a small flute angle is used.
• a point angle of a drill also has an influence on the amount of the cutting oil supplied to the point of the drill.
• the inventor also conducted a test so as to confirm the effect of a point angle of a drill on the amount of cutting oil supplied to the point. Through the test, the inventor found that if the point angle of a drill is in the range of 136°to 145°, preferably about 138°, the amount of cutting oil to the point is increased, thereby prolonging the lifespan of the drill.
• the invention can be applied irrespective of the diameter of a drill.
• a drill since oil holes are formed through the drill body, it is difficult to form such oil holes if a drill has a small diameter (for example, D3 or less). Furthermore, if oil holes are formed through such a drill, the rigidity of the drill itself is poor.
• the present invention can be applied to such a small diameter drill since it is not necessary to form oil holes through the drill body.
• burrs were generated on the walls or in the vicinity of drilled holes when about 8,000 holes were drilled through the workpiece of cast iron.
• burrs were generated on the walls or in the vicinity of the drilled holes when about 20,000 holes were drilled.
• the lifespan of the inventive drills was increased by about 3 times to 40 times as compared to the conventional drill.
• the inventive drill is not overloaded in general during drilling, whereby the performance of the drill can be stably maintained for a long time without being deteriorated by overheating or excessive cutting load. Consequently, it is possible to prevent or at least reduce burrs, which are produced on the wall or at the vicinity of a drilled hole due to the deterioration of the drill performance.
• the inventive drill can be manufactured by a method comprising steps of: forming flute lines with a lead angle on the circumferential surface of a preform (cylindrical rod), the lead angle being determined depending on a desired use; forming flutes with the lead angle along the flute lines; forming oil grooves 146 with a predetermined depth on the top surfaces of lands 144, which are produced as the flutes are formed; and performing a thinning operation. Since it is possible to omit a relatively highly difficult operation for forming oil holes with a predetermined lead angle through a drill body, the inventive drill can be fabricated through a simplified manufacturing process.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Drilling Tools (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=37713435

Family Applications (1)

Country Status (2)

Cited By (3)

Citations (4)

• 2006
  • 2006-01-23 KR KR1020060006745A patent/KR100649431B1/ko not_active IP Right Cessation
• 2007
  • 2007-01-22 WO PCT/KR2007/000365 patent/WO2007083967A1/en active Application Filing

Patent Citations (4)

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