JPH0120087Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a cutter with a blade attached with a tip having a special cutting edge structure, especially a spiral cutter having a structure that allows the tip itself to perform the function of a back blade without using a back blade. Regarding useful cutters.

The applicant has proposed a cutter that has a back edge at the end, in which the tip edge of the curved upward portion of the back edge is located slightly inward in the radial direction from the cutting edge of the cutter tooth, and the rake surface of the cutter tooth gradually becomes closer to the back edge. We have invented a cutter with a back edge that transitions to the inner surface of the curved portion of the back edge through the tip edge of the back edge (Patent No. 1125200). This cutter with a back edge is easy and economical to manufacture or install when the cutting edge is approximately parallel to the axis of the cutter. It is very difficult to manufacture a back blade that achieves the above effect due to its structure, and in reality, it is impossible due to manufacturing technology, assembly technology, and economic reasons. It is even considered.

Also, when re-sharpening the cutting blade of a spiral cutter, first remove the twisted back blade from the cutter, then similarly pull out the twisted cutting blade from the main body and hold this twisted cutting blade with a special chuck. After re-sharpening, it was necessary to reattach these cutting blades and the back blade. However, in the case of a spiral cutter, the positional relationship between the cutting edge and the back edge is very important, and therefore requires extremely high precision assembly. Therefore, this assembly is very difficult.
In addition, there are also accidents where the back blade loosens during rotation of the cutter after reassembly due to deformation of the cutting blade or back blade, and in practice, re-sharpening and reassembling of spiral cutters has been extremely difficult or impractical. It was impossible.

The present invention is a cutting edge structure that is particularly useful for spiral cutters, and the cutting edge itself is machined into a geometric shape that dynamically forms a back edge, allowing it to be economically cut into materials such as wood. To provide a cutter having a cutting edge capable of preventing tip cracking and back-cutting of cutting material.

According to this invention, the part that functions as the back blade is integrally formed on the cutting edge of the cutter, so when attaching the back blade, which is separate from the cutter, to the cutter, there will be a gap between the two, and the cutting edge of the cutter will There are no manufacturing or assembly problems with the back cutter, such as the back cutter not fitting properly, and is therefore particularly useful for spiral cutters with curved cutting edges.

In addition, in the present invention, the re-sharpening work can be accomplished quickly and reliably by the same procedure as the blade setting work described later.

A specific example will be described below.

FIG. 1 is a side view of a spiral cutter in which the present invention is embodied. Number 10 is a spiral cutter main body, and the main body 10 has four spiral cutting blades 12. A cutting tip 14 is attached to the tip of each of the blades 12 by a known method to perform substantial cutting. The chip 1
4 is twisted with respect to the axis of the cutter and extends at the same twist angle over the entire width of the cutter from one side to the other side.

FIG. 2 is an enlarged cross-sectional view of a portion of the tip 14 perpendicular to the cutter axis. Cutting edge 16 of tip 14
has a predetermined rake angle α and predetermined rake angle β.

The rake angle here refers to the tangent line X-X of the rake face at a predetermined point of the chip 14 (for example, the cutting edge 16 in FIG. 2) and the reference line (the tip of the chip 14 indicated by the cutting edge 16 in FIG. 2). This refers to the angle α formed by the line Y-Y connecting the center of the cutlet. Therefore, as a given point, that is, a predetermined point changes, the rake angle also changes. The clearance angle is defined by the line L-L formed by the flank surface of the chip 14, the tangent line M-M of the cutter at the tip of the chip 14 (cutting edge 16 in FIG. 2),
The angle β formed by

Further, the cutting edge 16 passes through a biting portion having a predetermined length t, and then passes through a rake face 1 facing radially inward as is known in the art.
8, and the rake face 18 has an R component of progressively smaller diameter. For this reason, the rake angle has a positive value within the predetermined length t of the tip end, but the value decreases as it goes toward the radially inward point. This rake face 18 then continues to a chip guide face 20 with a negative rake angle. The length t of the biting portion forming the rake angle α varies depending on the workpiece, cutter speed, etc., but is on average about 0.2 to 0.3 mm. Similarly, the dimension T from the cutting edge 16 to the lower end of the guide surface 20 is approximately 2
mm. The tip 14 having such a cutting component is initially fixed to the cutter body in the form of a simple torsion rod having no cutting component. Thereafter, a cutting operation is performed to form a cutting component on the outer edge of the chip. This cutting operation is usually performed by using diamond or the like to form the rake face 18, chip guide face 20, and flank face along a predetermined helix angle over the entire length of the spiral cutting edge. For this reason, there is no need for the difficult process of forming the back blade so that there is no gap between the cutting edge and the cutting edge, as was done in the past. It is only necessary to machine the chip guide surface 20 having the chip guide surface 20 in succession to the machining of the rake face 18 of the cutting blade.

FIG. 3 shows the cutting state of the spiral cutter according to the present invention. The spiral cutter rotates at a constant speed in the direction of arrow A. The work material is fed in the direction of arrow B at a constant feed rate. When the feed per tooth is F, F is smaller than the distance T between the tip of the tip 14, and the cutting depth is within the length t of the biting part. Chips cut between the biting portions are scooped from the cutting surface of the material by the rake face 18 and immediately continuously supplied to the inner chip guide surface 20. The guide surface 20 has a small diameter R component with a negative rake angle, and since the dimension from the cutting edge 16 to the lower end of the guide surface is preferably about 2 mm, the chips guided there will be removed by the spiral cutter. Due to the rotation and progress of the work material, the direction is forcibly and rapidly changed, and the material is easily bent and broken. For this reason, the chips are cut into short pieces of about 2 mm length that are easy to post-process at the same time as cutting, and even if the spiral cutter cuts in more than the specified amount, the chips will be cut into pieces with a length of about 2 mm. The blade is quickly broken on the guide surface 20, so that no excessive load is placed on the spiral cutter, and machining defects such as cracking of the tip of the workpiece and undercutting can be reliably prevented.

[Brief explanation of drawings]

FIG. 1 is a side view of a spiral cutter embodying the present invention, FIG. 2 is an enlarged cross-sectional view of a tip perpendicular to the cutter axis, and FIG. 3 is a diagram showing the state of cutting according to the present invention. Explanation of symbols, 10...Spiral cutter, 12
... Cutting blade, 14 ... Chip, 16 ... Cutting edge,
18... rake face, 20... chip guide surface, t...
Biting length, T...Length from the cutting edge to the lower end of the guide surface.

Claims (1)

[Claims for Utility Model Registration] A spiral cutter comprising a plurality of tips each having a cutting edge twisted in the axial direction, each of the tips being twisted in the axial direction of the spiral cutter. and a chip guide surface having a negative rake angle that is continuous with the rake face of the cutting edge over the entire length of the cutting edge inwardly in the radial direction, A spiral cutter characterized in that the chip guide surface provides a back-edge function that divides the chips cut by the cutting edge into lengths of about several millimeters for easy post-processing.