Drill, drilling unit, and drilling method

A drill comprising:

• a body without a back taper, the body having a flow path of a cutting oil inside, the flow path being branched to a first flow path and a second flow path inside the body;
• and
• a cutting edge part integrated with the body, the cutting edge part having a first supply port that supplies the cutting oil toward a workpiece, the first supply port being an outlet of the first flow path,
• wherein the body has a second supply port that supplies the cutting oil to a clearance formed between the body and a bush for positioning the body, the bush being used by inserting the body inside the bush, the second supply port being an outlet of the second flow path, the outlet of the second flow path being formed on an outer peripheral surface of the body, the second flow path having a pressure loss by which the cutting oil is not scattered from the second supply port in a radial direction of the body but exuded from the second supply port, and
• wherein the first flow path supplies a first quantity of the cutting oil to the first supply port while the second flow path supplies a second quantity of the cutting oil to the second supply port, the first quantity being not less than twice the second quantity.

A drill comprising:

• a body without a back taper, the body having a flow path of a cutting oil inside, the flow path being branched to a first flow path and a second flow path inside the body;
• and
• a cutting edge part integrated with the body, the cutting edge part having a first supply port that supplies the cutting oil toward a workpiece and in a direction that includes a vertical vector directed at an underlying surface of the workpiece, the first supply port being an outlet of the first flow path and positioned as to supply cutting oil to the underlying surface during drill rotation,
• wherein the body has a second supply port that supplies the cutting oil to a clearance formed between the body and a bush for positioning the body, the bush being used by inserting the body inside the bush, the second supply port being an outlet of the second flow path, the outlet of the second flow path being formed on an outer peripheral surface of the body, the second flow path having a pressure loss by which the cutting oil is not scattered from the second supply port in a radial direction of the body but exuded from the second supply port, wherein a cross section of at least a part of the second flow path has an area causing the pressure loss, and wherein a maximum width of the cross section of at least a part of the second flow path is not more than 0.5 mm, and
• wherein at least a part of the second flow path has been formed by a porous material or a clearance between a male screw and a female screw, the porous material or the clearance between the male screw and the female screw causing the pressure loss.

A drill comprising:

• a body without a back taper, the body having a flow path of a cutting oil inside, the flow path being branched to a first flow path and a second flow path inside the body;
• and
• a cutting edge part integrated with the body, the cutting edge part having a first supply port that supplies the cutting oil toward a workpiece and in a direction that includes a vertical vector directed at an underlying surface of the workpiece, the first supply port being an outlet of the first flow path and positioned as to supply cutting oil to the underlying surface during drill rotation,
• wherein the body has a second supply port that supplies the cutting oil to a clearance formed between the body and a bush for positioning the body, the bush being used by inserting the body inside the bush, the second supply port being an outlet of the second flow path, the outlet of the second flow path being formed on an outer peripheral surface of the body, the second flow path having a pressure loss by which the cutting oil is not scattered from the second supply port in a radial direction of the body but exuded from the second supply port, wherein a cross section of at least a part of the second flow path has an area causing the pressure loss, and wherein a maximum width of the cross section of at least a part of the second flow path is not more than 0.5 mm, and
• wherein the body and the cutting edge part form a holder that holds at least one cutting edge interchangeably.

A drill comprising:

• a body without a back taper, the body having a flow path of a cutting oil inside, the flow path being branched to a first flow path and a second flow path inside the body;
• and
• a cutting edge part integrated with the body, the cutting edge part having a first supply port that supplies the cutting oil toward a workpiece, the first supply port being an outlet of the first flow path,
• wherein the body has a second supply port that supplies the cutting oil to a clearance formed between the body and a bush for positioning the body, the bush being used by inserting the body inside the bush, the second supply port being an outlet of the second flow path, the outlet of the second flow path being formed on an outer peripheral surface of the body, the second flow path having a pressure loss by which the cutting oil is not scattered from the second supply port in a radial direction of the body but exuded from the second supply port, wherein at least a part of the second flow path has been formed by a porous material or a clearance between a male screw and a female screw, the porous material or the clearance between the male screw and the female screw causing the pressure loss, and
• wherein members forming second supply ports having different pressure losses respectively have been interchangeably attached to the body.