JPH11239911A - Throwaway cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a throwaway cutting tool which has firm fixing mechanism causing no position displacement of a tip against load affected in using. SOLUTION: A conical abutment 4 eccentric toward a rear end of a tool body is provided at a part corresponding to a head conical face 3 of a clamping member 8 in a tip seat side part of the tool body, while a cylinder part accepting hole of the clamping member 8, side wall and a female screw part 6 which ranges the side wall and corresponds with a male screw part 5 of a clamping member is provided in other tip seat side part, and a holder body tip side on a side wall of a cylinder part accepting hole 9 is a tool reference plane, so that a throwaway tip 2 is fixed by pressure of the tip seat side part and pressure of the rear end of the tool body from a pin hole side of the throwaway tip 2 by a cylinder part of the clamping member 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type cutting tool, and more particularly, to an improvement in a rigid rigid insert-fixing mechanism which can be mounted with high precision even with a small-diameter tool.

[0002]

2. Description of the Related Art In a throw-away type cutting tool, a fixing mechanism of a throw-away tip is one of important factors for improving sufficient rigidity and accuracy. In particular, in the case of relatively small-diameter ball end mills used for finishing of dies, etc., the space for the fixing mechanism for the indexable insert is limited, so it is difficult to provide a firm fixing mechanism and the rigidity is insufficient. For this purpose, various devices have been devised. In general, the bottom surface of the throw-away tip of the tool body 1 and the end surface of the throw-away tip 2 are engaged with each other so as to maintain the mounting accuracy at the time of replacing the throw-away tip. 1). As an improvement, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent No. 252714 (hereinafter referred to as Conventional Product 2), the bottom surface of the tip seat of the tool body is formed as an arc-shaped concave portion, and the bottom surface of the indexable insert is formed as an arc-shaped convex portion having the same or a slightly larger radius of curvature. There is a tool in which the center line of the insert is automatically matched with the center line of the tool body when the indexable insert is attached, so that the attachment accuracy is improved.

[0003]

A sectional view of a mechanism for fixing these throw-away tips is shown in FIG. 1 for a conventional product 1 and in FIG. 2 for a conventional product 2. As shown in FIG. In both the conventional products 1 and 2, the position of the screw 8 is determined by the contact between the conical head 3 of the screw and the receiving surface 4 provided on the tool body and the contact between the male screw portion 5 of the fastening member and the corresponding female screw portion 6. Therefore, it is difficult to maintain the mounting accuracy of the indexable insert. That is, due to the clearance between the male screw portion and the female screw portion, the tightening member slightly moves due to the load applied during use of the tool, which adversely affects the mounting accuracy of the indexable insert. Particularly, in the case of performing three-dimensional curved surface processing with a ball end mill, etc., not only the axial and radial loads of the tool, but also various combinations such as inclined cutting and spiral cutting, and the axial load is the base end of the tool body. Not only the direction but also the load in the tip direction occurs, and the magnitude and direction of the load are constantly changing. Therefore, it is not sufficient to restrict only the tool tip side at the thread portion of the fastening member.

[0004]

SUMMARY OF THE INVENTION In view of the above, the present invention has been made. An object of the present invention is to provide a throw-away type cutting tool having a strong fixing mechanism in which the position of the throw-away tip is not disturbed even when a load is applied during use of the tool.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a hollow chip seat 7 provided in a slit shape at the tip of a tool body.
In a throw-away type cutting tool in which a throw-away insert 2 is sandwiched and fixed with a fastening member, a tool body 1
The tip seat side surface portion 7a is provided with a cone receiving surface eccentric in the direction of the rear end of the tool body at a portion corresponding to the head cone surface 3 of the fastening member 8, and the other chip seat side surface portion 7b has a cylindrical receiving hole. 7 and the side wall 9a thereof, and fixing of the throw-away tip 2 is performed by pressing the tip seat side portions 7a and 7b,
This is performed by pressing the inner wall surface of the pin hole 11 of the throw-away tip against the rear end side of the holder body by the cylindrical portion 10 of the fastening member, and the side wall 9a of the cylindrical portion receiving hole.
This is a throw-away type cutting tool with
More preferably, the depth of the cylindrical portion receiving hole 9 is set at 2 to the blade diameter.
30%, and the cylindrical portion receiving hole 9 is an elongated hole elongated in the axial direction. The eccentricity of the cone receiving surface includes not only a case where the axis is shifted in parallel to the axis of the female screw portion but also a case where it forms an angle with the axis of the female screw portion.

[0006]

The fixing of the throw-away tip is performed as follows. FIG. 3 is a front view of a tool body, FIG. 4 is a front view of a throw-away tip used therein, FIG.
FIG. 3 is a sectional view showing a main part of the throw-away tip of the present invention fixed. From these figures, when the throw-away tip 2 is inserted into the slit-shaped tip seat of the tool body 1 and the fastening member 8 is tightened, the conical receiving surface 4 becomes closer to the tool base end (toward the tip seat bottom surface 12). Since the eccentricity is Δt, the head 3 of the fastening member is pressed against the conical receiving surface 4. At this time, since the fastening member 8 is slightly bent, the lower end 10b of the cylindrical portion of the fastening member is pressed by the side wall 9a on the tip end side of the cylindrical receiving hole. Tightening member cylindrical part upper end 1
0a pushes the throw-away tip 2 and the tip seat bottom 1
At the same time, the tip is firmly fixed since the tip seat side faces 7a and 7b sandwich the throw-away tip 2. At this time, the position of the tightening member 8 is adjusted by the pressure between the lower end 10b of the cylindrical portion of the tightening member and the side wall 9a on the tip end side of the cylindrical portion receiving hole. Independent of machining accuracy,
The pressing force of the upper end 10a of the fastening member cylindrical portion against the throw-away tip 2 is stabilized. Therefore, the tip seat side surface 7
The balance between a and 7b and the pressing force on the throw-away tip 2 is as designed irrespective of the thread processing accuracy. In addition, the lower end 10b of the tightening member cylindrical portion restrains not only the tool tip side but also the outer peripheral side of the tool when viewed from the axial direction of the tightening member, so that the throw-away tip is firmly fixed against loads from all directions. You can.

The depth of the cylindrical receiving hole 9 is 2 to 2 of the blade diameter.
It is preferably 30%, more preferably 10 to 20%. If this is too shallow, the screw-in possible amount after the lower end 10b of the cylindrical portion comes into contact with the side wall 9a on the tip end of the cylindrical portion receiving hole in the process of screwing the fastening member 8 is short, and the cylindrical portion receiving hole 9 is sufficient for the lower end 10b of the cylindrical portion. If you can not press with a strong force and too deep,
This is because the length of the female screw portion 6 cannot be sufficiently obtained, and the mounting strength of the throw-away tip is insufficient. The side wall 9a on the distal end side of the cylindrical receiving hole does not need to be perpendicular to the tip seat side surface 7b of the tool. For example, it can be inclined so that a strong pressing force can be obtained by screwing in the fastening member 8 with a small amount.

If the cylindrical portion receiving hole 9 is an elongated hole in the axial direction, the clearance between the cylindrical portion lower end 10b and the cylindrical portion receiving hole rear end side wall 9b can be ensured, and the cylindrical portion receiving hole tip side wall 9a. Can be reliably pressed, and the fastening member 8 can be easily screwed. The clearance is sufficiently smaller than Δt for securely pressing the side wall 9a on the distal end side of the cylindrical receiving hole, but may be larger than Δt for facilitating the screwing.
However, if it is too large, it affects the rigidity of the tool.
Should stay within double. When the clearance between the pin hole 11 of the throw-away tip and the cylindrical portion 10 of the fastening member 8 is 3 μm to 13 μm, the value of the eccentricity Δt of the conical surface is preferably 20 to 100 μm, more preferably 30 to 50 μm. If this value is too small, the pressure on the throw-away tip will be insufficient, and if it is too large, the load on the fastening member and the tool body will be excessive, which may cause breakage during use. When the clearance between the pin hole 11 and the cylindrical portion 10 is increased, the position of the male screw portion 5 and the conical receiving surface 4 must be changed toward the rear end of the tool body (toward the tip seat bottom surface 12). The shape of the cylindrical portion receiving hole 9 is not limited to the elongated hole shape shown in FIG. 7 and may be any shape as long as the fastening member cylindrical portion lower end 10b is constrained on the tool tip side and the tool outer peripheral side. According to the present invention, in order to accurately position the indexable insert, as shown in FIG.
It is more effective if combined with the shape provided with 3. This is because, due to the clearance generated by the tolerance of the thickness of the throwaway tip and the groove width of the tip seat, it is possible to eliminate the gap between the tip and the tip seat side surface near the tip seat bottom surface generated when the tip is fixed, Stable fixing of the throw-away tip is realized. Hereinafter, the present invention will be described in detail based on examples.

[0009]

FIG. 3 shows an example applied to a ball end mill having a blade diameter D = 10 mm. A tip seat 7 formed in a slit shape is provided at the tip of the tool body 1. The throw-away tip 2 is inserted into the tip seat 7, and the throw-away tip 2 is detachably fixed by a fastening member 8. The tightening member 8 is manufactured with a high precision in which the circumferential deviation between the conical head 3 and the cylindrical portion 10 is 10 μm or less, and the diameter tolerance of the cylindrical portion is 10 μm or less. FIG. 6 shows a cross-sectional view of the attachment of the throw-away tip. When the tightening member 8 is tightened, the conical receiving surface 4 corresponds to the conical head 3 and the cylindrical receiving hole 9 corresponds to the lower end 10b of the tightening member, and the conical receiving surface 4 extends toward the rear end of the tool body. The force for pressing the pin hole 11 of the throw-away tip 2 with the cylindrical portion 10 is exerted by the eccentric amount Δt (set to 40 μm in the present embodiment), and the throw-away tip 2 is applied to the tip seat side surfaces 7a, 7b.
Pressing force works to fix the chip. At this time, the lower end 10b of the cylindrical portion is received by the side wall 9a on the tip end side of the cylindrical receiving hole of the cylindrical receiving hole 9, and the gap between the lower end 10b of the cylindrical portion and the cylindrical receiving hole 9 is substantially 1/2 circle without any gap. Become. For this reason, since the fastening member is restrained at the tool tip side and the tool outer peripheral side, the throw-away tip continues to be firmly pressed against the tip seat bottom surface even with loads from all directions. At this time, since the clearance between the cylindrical portion receiving hole 9 and the side wall 9b on the rear end side of the cylindrical portion receiving hole was set to 0.1 mm, there was no inconvenience such as being caught by the screwing of the fastening member.

Although the present invention has been described with respect to a ball end mill, it can be applied to various shapes such as a square or radius type end mill and a drill. For example, as another embodiment, FIG. 9 shows a plan view of a ball end mill in which the bottom surface of the throw-away tip is a convex V, and FIG. 10 shows a plan view of a throw-away tip used for this. FIG. 11 is a plan view when applied to a square end mill, and FIG. 12 is a plan view of a throw-away tip used in this case.

[0011]

According to the present invention, the position of the tightening member is hard to move even in various directions and loads during use of the tool, and the throw-away tip is stably pressed. It is possible to maintain high accuracy.

[Brief description of the drawings]

FIG. 1 shows a sectional view of a main part of a conventional product 1. FIG.

FIG. 2 is a sectional view of a main part of a conventional product 2;

FIG. 3 shows a front view of an embodiment of the present invention.

FIG. 4 shows a front view of a throw-away tip used in the embodiment shown in FIG.

FIG. 5 shows a front view of the fastening member.

FIG. 6 is a sectional view of a main part of the embodiment shown in FIG. 3 in a fixed state of the throw-away tip.

FIG. 7 is a sectional view taken along the line AA of FIG. 6;

FIG. 8 is a sectional view showing a main part of another embodiment of the present invention.

FIG. 9 shows a front view of another embodiment of the present invention.

FIG. 10 is a front view of a throw-away tip used in the embodiment shown in FIG. 9;

FIG. 11 shows a front view of another embodiment of the present invention.

FIG. 12 shows a front view of a throw-away tip used in the embodiment shown in FIG.

[Description of Signs] 1 Tool body 2 Throw-away tip 3 Conical head 4 Conical receiving surface 5 Male thread 6 Female thread 7 Tip seat 7a, 7b Tip seat side face 8 Tightening member 9 Cylindrical receiving hole 9a Cylindrical receiving hole Front end side wall 9b Rear end side wall of cylindrical part receiving hole 10 Tightening member cylindrical part 10a Tightening member cylindrical part upper end 10b Tightening member cylindrical part lower end 11 Pin hole 12 Chip seat bottom surface 13 Slot slot Δt Eccentric amount toward the rear end of tool body

Claims (3)

[Claims] 1. A throw-away type cutting tool in which a throw-away tip is sandwiched by a hollow tip seat provided in a slit shape at a tip end portion of a tool body and fixed by a fastening member. Is provided with a conical receiving surface eccentric in the direction of the rear end of the tool body at a portion corresponding to the conical surface of the head of the fastening member, and the other side of the tip seat has a cylindrical receiving hole of the fastening member and a side wall thereof. A female screw portion corresponding to the male screw portion of the tightening member is provided on the side wall, the fixing of the throw-away tip is performed by pressing the tip seat side surface portion, and the tool body is inserted from the pin hole side surface of the throw-away tip by the cylindrical portion of the tightening member. A throw-away type cutting tool, wherein the cutting is performed by pressing to a rear end side, and a side wall of the cylindrical portion receiving hole is used as a reference mounting surface. 2. The indexable cutting tool according to claim 1, wherein the depth of the cylindrical receiving hole is 2 to 30% of the blade diameter.
A throw-away cutting tool characterized by the following. 3. The indexable cutting tool according to claim 1, wherein the cylindrical receiving hole is an elongated hole in the axial direction.