Proposed is a drilling tool for drilling workpieces, having a tool tip and a basic body and a core, wherein the basic body has at least one main groove as at least one helical depression, for the purpose of realizing a conveying helix in each case. For the purpose of prolonging the service life, the core, in a first portion that starts at the tool tip and/or extends to the tool tip, has a constant cross-sectional area perpendicular to the axis of rotation and, in an adjoining second portion, counter to the direction of advance, has a cross-sectional area that increases, at least in portions.

A drill according to an embodiment includes a bar-shaped drill body extending along a rotation axis, a cutting edge located at a front end of the drill body, and a first flute extending spirally from the cutting edge toward a rear end of the drill body. The first flute includes a first region which is located close to the front end and has a helix angle 1, and a second region which is located closer to the rear end than the first region and has a helix angle 2 smaller than the helix angle 1. The second region includes an elongated protruding part along the first flute.

A drill bit for drilling into masonry or rock includes a drilling head at its forward end, a clamping shank at its rearward end, and a helical conveying portion extending between the drilling head and the shank. The helical conveying portion includes at least two helically extending flutes separated by at least two helically extending webs. The helical conveying portion has a changeover portion, a pre-changeover portion between the drilling head and the changeover portion, and a post-changeover portion between the changeover portion and the shank. In the pre-changeover portion, the flutes have a pre-changeover pitch, the first web has a first pre-changeover web width , and the second web has a second pre-changeover web width . In the post-changeover portion, the flutes have a post-changeover pitch, the first web has a first post-changeover web width , and the second web has a second post-changeover web width . The post-changeover pitch is greater than the pre-changeover pitch, the first post-changeover web width is less than the first pre-changeover web width , and the second post-changeover web width is greater than the second pre-changeover web width .

A cutting tool body includes a first member and a second member, both having a substantially cylindrical shape, and arranged such that a tool body central axis coincides with a central axis of each of the first and the second members. The first member has a tool characteristic of a first magnitude and the second member has the tool characteristic of a second magnitude, different from the first magnitude. The cutting tool body includes a transition member arranged between the first and second members and connected at a first end to the first member and at a second end to the second member. The tool characteristic in the transition member is of the first magnitude at the first end and of the second magnitude at the second end. The transition member has a transition region between the first and the second ends in which the tool characteristic transforms from the first magnitude to the second magnitude.

A twist drill with a multi-step drill point includes a shank and a cutting portion. The cutting portion is provided with a spiral flute and a body clearance. A tip of the cutting portion is provided with a chisel edge and a cutting edge. A flank face connected with the cutting edge is provided with a stepped groove which divides the cutting edge into several sections. A pitch of the stepped groove gradually decreases along a direction from the tip of the cutting portion to the shank.

The rotatable cutting tool includes a cutting portion extending from the front end and a mounting portion extending from the rear end. The cutting portion includes a front end face surface and a peripheral surface extending from the front end face surface towards the mounting portion. The peripheral surface includes first helical flutes extending from the front end to a first helical flute rear end and second helical flutes extending from a second helical flute front end to a second helical flute rear end. The first helical flutes are helically aligned about the longitudinal axis and form a first helix angle. The second helical flutes are helically aligned about the longitudinal axis and form a second helix angle. The first helix angle decreases in absolute value away from the front end and/or that the second helix angle increases in absolute value away from the front end.

The present invention is concerned with twist drills for drilling of composite materials such as carbon fibre reinforced plastic (CFRP) and glass fibre reinforced plastic (GFRP). The present invention proposes that a twist drill (2) is provided with a variable helix having a defined start and finish helix angle, in combination with primary and secondary relief angles such that the drill (2) is adapted to minimise thrust force, particularly when used for drilling fibre-containing composite materials and especially for hand drilling. Start and finish helix angles of 50 and 10; 50 and 30; and 30 and 10 have been shown to provide excellent cutting performance and exit hole quality. A large secondary chisel edge angle (24) has also been found to contribute to excellent performance with composite materials, including stack machining.

A drill bit includes a shank extending along a bit axis and a body with a proximal end adjacent the shank and a distal end opposite the proximal end. The body defines a plurality of axially stacked, progressively sized steps including a first step at the distal end and a terminal step at the proximal end. The drill bit also includes a flute in the body. The flute defines an elongated groove that extends from the distal end to the proximal end. The drill bit further includes a plurality of cutting edges formed in the body. Each cutting edge is disposed along one of the plurality of steps and defines a helix angle and a rake angle. The helix angle of the cutting edge at the terminal step is greater than the helix angle of the cutting edge at the first step. A ratio of the helix angle to the rake angle of the cutting edge at the first step is in a range from 0.5 to 2.4, and a ratio of the helix angle to the rake angle of the cutting edge at the terminal step is in a range of 0.9 to 1.7.

The present invention relates to a tool bit replaceable rotary cutting tool and a rotary cutting method and a tool bit mounting method thereof and belongs to the field of hole machining in the machining industry. At present, a twist drill for drilling is of an integrated structure, and when service life of a tool bit is exhausted, the whole drill is required to be replaced, so that cost is relatively high. For a tool bit replaceable drilling tool, in a drilling process, radial and axial acting forces on a tool bit are relatively strong and thus may cause the conditions of imprecise drilling caused by radial displacement of the tool bit at a joint and the like, a replaceable structure of the tool bit makes the joint of the tool bit of the drilling tool relatively weak and a design of a chip groove makes a substrate of the drilling tool weaker. According to the tool bit replaceable rotary cutting tool of the present invention, a tool bit is detachably connected with a tool bar, and V-shaped positioning surfaces are adopted for a joint of the tool bit and the tool bar, so that a good tool bit positioning and fixation effect is achieved, and the tool bit is unlikely to deviate; a design with different helical angles is adopted for a chip groove, so that strength of the tool bar is strengthened; due to design of cooling guide grooves, a cooling effect is improved; and the tool bit is easy to mount and dismount.

A rotary tool may include a body, the body may include a cutting edge and a first groove. The first groove may include a first region having a first helix angle, a second region having a second helix angle, a third region having a third helix angle, a fourth region having a fourth helix angle, and a fifth region having a fifth helix angle. The fourth helix angle and the fifth helix angle may each decrease from a side of a first end toward a second end. A decreasing range of a value of the fourth helix angle of the fourth region may be less than a decreasing range of a value of the fifth helix angle of the fifth region. A length of the fourth region may be greater than a length of the fifth region.