JPH02180518A - Soldering type drilling tool - Google Patents

Abstract

PURPOSE:To heighten joining strength for preventing the breakage of a cutting edge by cutting out the shank-side joining part on the end surface of a shank in a V-shape, and forming the tip-side joining part in a projected V-shape, and by forming flat surfaces with a difference in level on both sides thereof for abutting and joining the end surfaces of the twisted tips. CONSTITUTION:On the tool rotating rear side of chip discharging twisted grooves 11a, 11b (not shown) of a steel shank 1, tip seats 12a, 12b having the same lead as the above grooves are formed, on which twisted tips 2a, 2b are soldered. On the end surface of the shank 1, a V-shaped cutout 13 making the apex of the center O (not shown) of the tool axis is provided, while on the end 3 of cemented carbide, a V-shaped projected part 31 for fitting thereto is provided, and on both sides of the top 32 thereof, flat surfaces 33a, 33b are formed. The flat surface 33a is formed to be lower than the top 32 by a prescribed value, and the flat surface 33b is formed to be deeper than the flat surface 33a in the difference in level, and the end surfaces 21a, 21b of the twisted tips 2a, 2b are abutted and solder-joined on the flat surfaces 33a, 33b.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a brazing type milling tool, that is, a chip is brazed to the chip seat of a steel shank, and a solid cemented carbide is attached to the end of the tool. This relates to cutting tools such as brazed drills and end mills.

[Prior art] Conventionally, when joining a solid carbide cutting blade to a steel shank, a ■-shaped groove was formed on the upper end of the cemented carbide cutting blade and a V-shaped protrusion was provided on the end face of the shank. Japanese Utility Model Publication No. 55-37284 discloses a carbide drill in which the two are fitted and brazed together.

In addition, Japanese Patent Publication No. 54-6420 also states that when joining a solid carbide cutting blade to a steel shank, a horizontal plane is formed between the apex angles of the V-shaped part, and the margin edge part of the drill is attached to this horizontal plane. A cemented carbide drill is disclosed in which the shank and the cemented carbide cutting blade are joined to each other so as to include the shank and the cemented carbide cutting blade.

[Problems to be solved by the invention However, the joint surface 5 of the cemented carbide drill disclosed in Lami-Jitsu Publication No. 55-37284 has a 7-shape with the center of the drill shaft as a reference. , this means that when the drill rotates, the tangent to the joint surface rotates at the same position.

Therefore, in a drill where only the tip cutting edge is involved in cutting and the margin part mainly serves as a guide, even if the tangent to the joint surface rotates at the same position, there is a risk of scratching the inner circumference of the hole in the rigid material. Although this is not a small problem, in cutting tools such as end mills where both the tip cutting edge and the outer cutting edge participate in cutting, inclusions such as the low-hardness wax layer and copper plate on the joint surface mentioned above may occur during cutting. There is a risk that a gap will be created at the joint surface due to wear or chipping, and uncut parts will appear on the workpiece surface, which will greatly deteriorate the accuracy of the workpiece surface and significantly shorten the tool life.

Further, even in a carbide drill according to Japanese Patent Publication No. 54-6420, in which a horizontal portion is provided on the apex surface of the V-shaped portion, the horizontal surface portion 5 is formed at the same position on both sides of the outer periphery of the drill. It has the same problems as the carbide drill described above, and is not suitable for end mill cutting in which both the tip cutting edge and the outer peripheral cutting edge perform cutting operations.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and is made by joining a solid cemented carbide, which has extremely high tool rigidity and is capable of high-efficiency cutting, to a steel shank. In a tool that is suitable for deep cutting of difficult-to-cut materials such as a mold in which a cutting edge is formed from the side to the shank, the joint surface between the steel shank and the cemented carbide is improved to allow the cutting edge to participate in cutting. To provide a milling tool which can obtain an extremely high-precision cut surface without leaving any uncut parts on the cut surface even when cutting, has a high bonding strength between a steel shank and a cemented carbide, and can greatly extend the tool life. The purpose is to

[Means for Solving the Problems] The present invention solves the above-mentioned problems by the following means.

That is, it is a milling tool in which a chip is brazed to the chip seat of a steel shank, and a cemented carbide is brazed to the end of the shank, and the cutting is performed from the cemented carbide at the end to the chip of the chip seat. A blade is formed, and the shape of the joint between the shank end face and the end face of the cemented carbide is made by cutting the shank end face side into a substantially V-shape, and cutting the end face side of the cemented carbide into a substantially V-shape corresponding to the notch. A flat surface having a convex portion and a step on both sides of the convex portion is formed, and before joining these by brazing, the end face of the chip located in the chip seat of the shank is formed on both sides of the convex portion of the cemented carbide. They are joined so that they are in contact with or close to a plane.

[Operation of the Invention] The present invention uses the above-described means to ensure that the plane formed on the cemented carbide side and the end face of the tip brazed to the tip seat of the steel shank are aligned with respect to the axis of the tool. They are joined with perpendicular surfaces, and the strength of the back metal at the joint is greatly increased so that it can easily withstand the cutting load, preventing chip breakage or chipping.

In addition, the solder layer extends to the end of the chip in the chip seat of the shank, and brazing greatly increases the strength and reduces peeling of the chip from the chip seat even if an external load is applied.

In addition, since the flat surfaces on both sides of the substantially ■-shaped convex portion provided on the cemented carbide that the chip contacts or approaches are stepped, each end face on the flat side of the chip is , are arranged at different positions with respect to the axial direction of the tool, and the end surface joint between the chip cutting edge and the cemented carbide cutting edge is
The joint position shifts in the tool axis direction by the step difference mentioned above. Therefore, during cutting, one joint part is cut by the other cutting blade, and the other joint part is cut by one cutting blade. This prevents any uncut parts from being left on the machined surface.

[Example code] Hereinafter, embodiments will be described based on the attached drawings.

The figures all show milling tools according to the present invention.
Figure 1 is a front view, Figure 2 is a bottom view of Figure 1, Figure 3 is a right side view of Figure 1, Figure 4 is a sectional view taken along line B-B in Figure 1, and Figure 5 is a steel shank. This is a cross-section showing the main part of
(a) is a front view, (b) is a bottom view of (a), (c)
is the right side view of (a), and Figure 6 shows the cemented carbide tip, of which (a) is a top view of (b), (b) is a front view, and (c) is For example, the right side view.

In the figure, twisted grooves 11a and 11a for discharging chips are provided with a predetermined lead on one end side of a steel shank body 1.
A chip seat 12a12b having substantially the same lead as the groove lead is formed in the axial direction on the rear side of this groove when the tool rotates, and twisted chips 2a, 2b are connected to the chip seat.
These are joined by brazing.

The end surface side of the shank body described above is shown in FIGS.
As shown in c), a substantially V-shaped notch 13 having an apex angle at the center 0 of the tool shaft is provided.

The cemented carbide tip 3 that is fitted into the notch 13 described above and joined by brazing is connected to the notch 13 on the upper surface side as shown in FIGS. 6(a), (b), and (c). A V-shaped protrusion 31 that can be fitted is provided, and flat surfaces 33a and 33b are formed on both sides of the top 32 of the V-shaped protrusion.

The positional relationship between the planes 33a and 33b is such that the plane 33a is lower by a predetermined value H (1.8 mm in the embodiment) than the top 32, and the plane 33b is lower by a predetermined value H (1.8 mm in the embodiment) than the plane 33a. It is formed to have a step that is deepened by the same amount.

The shank body 1 and the cemented carbide tip 3 formed as described above have a copper plate or the like between the notch 13 provided in the shank and the V-shaped protrusion 31 formed in the cemented carbide tip. It is also possible to braze and join without using an intervening material.

After joining in this way, the chip seat 12 of the shank is
a, 12b are the tip surfaces 21a of the twisted tips 2a, 2b.
, 21b are provided on the cemented carbide tip 3.
3b, so as to be brought into contact with or close to it, and to be joined by brazing.

In the above embodiment, the tips 2a and 2b were brazed to the tip seat 12a12b after the cemented carbide tip was brazed to the shank. It is also possible to braze the parts and then braze them to the cemented carbide tip and shank.

The milling tool A made as described above is chucked into a grinding machine, and the machine cuts the flanks 22a, 22b into the tool A.
The rake faces 23a, 23b and cutting edges 24a, 4b are formed by grinding.

This embodiment has been explained using a ball end mill as an example, but this can also be applied to a milling tool such as an end mill or a drill, or a milling tool whose cutting edge has a straight peripheral cutting edge without a lead, and which is integrated with a shank body. Needless to say, the cutting tool may be used in a milling tool having a cutting edge formed thereon.

[Effects of the Invention] The present invention has the configuration described above, so that the plane formed on the cemented carbide tip side and the end of the tip in the tip seat of the shank body are aligned with respect to the axis of the tool. Because they are joined with perpendicular surfaces, the strength of the back metal at the joint is greatly increased, allowing it to withstand intermittent severe cutting loads and preventing breakage or chipping of the cutting edge.

In addition, the solder layer spreads all the way to the end of the chip in the chip seat of the shank, greatly increasing the brazing strength and preventing the chip from peeling off from the chip seat even if an external load is applied due to an unexpected accident. It has become extremely low.

Since the planes on both sides of the approximately V-shaped convex portion provided on the cemented carbide tip that bring the tip end surfaces into contact with or close to each other are provided with steps, each end surface on the plane side of the tip are arranged at different positions with respect to the axial direction of the tool, and the end surface joints are located at different positions in the axial direction of the tool by the step difference, so during cutting, one joint part is connected to the other. One cutting blade cuts the other joint, and one cutting blade cuts the other joint, resulting in a highly accurate work surface without leaving any uncut parts on the work surface, and extremely reducing wear on the joint. This has the effect of significantly extending tool life.

[Brief explanation of the drawing]

The figures all show milling tools according to the present invention.
Figure 1 is a front view, Figure 2 is a bottom view of Figure 1, Figure 3 is a right side view of Figure 1, Figure 4 is a sectional view taken along line B-B in Figure 1, and Figure 5 is a steel shank. This is a cross-section showing the main part of
(a) is a front view, (b) is a bottom view of (a), (C)
is the right side view of (a), and Figure 6 shows the cemented carbide tip, of which (a) is a top view of (b), (b) is a front view, and (c) is For example, the right side view. 1-m-shank body 2a, 2b~-1 tip 3-
m-Cemented carbide tip 12a, 12b chip seat 13
-m-notches 21a, 21b---tip end surface 31
-～-■ Letter-shaped convex part 32---Top part of V-shaped convex part 3
3a, 33b--One plane Fig. 1

Claims (1)

[Claims] (1) A milling tool in which a tip is brazed to the tip seat of a steel shank, and a cemented carbide is brazed to the end of the shank, with the tip extending from the cemented carbide at the end to the tip of the tip seat. A cutting edge is formed, and the shape of the joint between the shank end face and the end face of the cemented carbide is a substantially V-shaped notch on the shank end face side, and a substantially V-shaped notch corresponding to the notch on the end face side of the cemented carbide. A convex portion of the cemented carbide is formed, and a plane with a step is formed on both sides of the convex portion, and when joining these by brazing, the end face of the chip in the chip seat of the shank is placed on both sides of the convex portion of the cemented carbide. A brazed milling tool characterized in that the tool is joined so as to be in contact with or in close proximity to a flat surface formed on the surface.