JP3971522B2 - Throw-away cutting tool - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a throw-away type cutting tool, and more particularly, to an improvement in a fixing mechanism for a throw-away tip having high rigidity and capable of high-precision mounting even with a small-diameter tool.
[0002]
[Prior art]
In the throw-away type cutting tool, the fixing mechanism of the throw-away tip is one of the important elements for increasing the sufficient rigidity and accuracy. In particular, in relatively small-diameter ball end mills used for finishing molds, etc., the space for installing the throw-away tip fixing mechanism is limited, making it difficult to provide a firm fixing mechanism and insufficient rigidity. Therefore, various devices have been made conventionally.
Generally, the throwaway tip seat bottom of the tool body 1 and the end face of the throwaway tip 2 are engaged with each other to maintain the mounting accuracy when replacing the throwaway tip (hereinafter referred to as the conventional product). 1).
As an improvement of this, as disclosed in JP-A-8-252714 (hereinafter referred to as conventional product 2), the bottom surface of the tool seat has an arcuate recess and the bottom surface of the throw-away tip is the same or slightly larger. There is a tool whose mounting accuracy is improved by using an arc-shaped convex portion with a radius of curvature so that the tip center line and the tool body center line automatically coincide with each other when the throw-away tip is attached.
[0003]
[Problems to be solved by the invention]
In order to explain the fixing mechanism of these throw-away tips, a sectional view thereof is shown in FIG. 1 for the conventional product 1 and in FIG. 2 for the conventional product 2.
In both the conventional products 1 and 2, the position of the screw 8 is determined by the contact between the conical head portion 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 throw away tip mounting accuracy. 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 throwaway tip mounting accuracy.
In particular, in cases where 3D curved surface processing is performed with a ball end mill or the like, not only the axial and radial loads of the tool but also various combinations such as inclined cutting and spiral cutting are performed, and the axial load is the base end of the tool body. Since not only the direction but also the load in the tip direction occurs and the magnitude and direction of the load are constantly changing, it is not sufficient to restrain the tool tip at the screw thread portion of the fastening member.
[0004]
[Object of the present 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 does not change even with respect to a load acting during use of the tool.
[0005]
[Means for Solving the Problems]
Therefore, the present invention provides a throwaway cutting tool in which a throwaway tip is sandwiched between a hollow tip seat provided in a slit shape at the tip of a tool body and fixed with a tightening member. Is provided with a cone receiving surface that is eccentric in the direction of the rear end of the tool body with respect to the center line of the clamping member at a portion corresponding to the conical surface of the head of the clamping member. The cylindrical portion receiving hole and the side wall thereof and a female screw portion corresponding to the male screw portion of the fastening member are provided, and the throwaway tip is fixed by pressing by the side surface portion of the tip seat and by the cylindrical portion of the fastening member. performed by the pressure from the pin hole side of the away tip to the rear end of the tool body, and the mounting base is brought into contact with the cylindrical portion of the fastening member and the cylindrical portion receiving the side wall of the hole It is a throw-away type cutting tool characterized by having a surface, and more preferably, the depth of the cylindrical portion receiving hole 9 is 2 to 30% of the blade diameter, and the cylindrical portion receiving hole is a tool shaft. Long holes in the direction. The eccentricity of the conical receiving surface includes not only the case where the axis is shifted parallel to the axis of the female screw part but also the case where the angle is formed with the axis of the female screw part.
[0006]
[Action]
The throw-away tip is fixed as follows.
FIG. 3 is a front view of the tool body, FIG. 4 is a front view of a throwaway tip used therefor, FIG. 5 is a fastening member, and FIG.
From these figures, when the throw-away tip 2 is inserted into the slit-like tip seat of the tool body 1 and the fastening member 8 is fastened, the conical receiving surface 4 is on the tool proximal side (in the direction of the tip seat bottom surface 12). Since the head is eccentric by 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 cylindrical portion lower end 10b of the fastening member is pressed by the cylindrical portion receiving hole distal side wall 9a. The upper end 10a of the tightening member cylindrical portion presses and pushes the throwaway tip 2 against the tip seat bottom surface 12 and at the same time the tip seat side surfaces 7a and 7b sandwich the throwaway tip 2 so that the tip is firmly fixed.
At this time, the position of the tightening member 8 by the press between the cylindrical portion lower end 10b of the tightening member and the side wall 9a of the cylindrical portion receiving hole is the screw thread of the male screw portion 5 of the tightening member or the screw thread of the female screw portion 6 of the tool body. Regardless of the processing accuracy, the pressing force of the fastening member cylindrical portion upper end 10a against the slow-away tip 2 is stabilized.
Therefore, the balance with the pressing force of the tip seat side surfaces 7a and 7b to the throwaway tip 2 is as designed regardless of the processing accuracy of the thread. In addition, the tightening member cylindrical portion lower end 10b restrains not only the tool tip side but also the tool outer peripheral side when viewed from the axial direction of the tightening member, so that the throwaway tip can be firmly fixed against loads from all directions. It can be done.
[0007]
The depth of the cylindrical portion receiving hole 9 is 2 to 30% of the blade diameter, more preferably 10 to 20%. If this is too shallow, the amount that can be screwed in after the cylindrical portion lower end 10b and the cylindrical portion receiving hole tip side wall 9a come into contact with each other in the process of screwing the tightening member 8 is short, and the cylindrical portion receiving hole 9 is sufficient for the cylindrical portion lower end 10b. This is because the internal thread portion 6 is not sufficiently long and the attachment strength of the slow-away tip is insufficient if it cannot be pressed with a strong force and is too deep.
The side wall 9a on the distal end side of the cylindrical portion 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 with a small number of fastening members 8.
[0008]
Further, if the cylindrical portion receiving hole 9 is a long hole that is long in the tool axis direction, a clearance between the cylindrical portion lower end 10b and the cylindrical portion receiving hole rear end side wall 9b can be secured, and the cylindrical portion receiving hole front end side wall 9a can be formed. It can be surely pressed, and the fastening member 8 can be easily screwed. The clearance is sufficient within Δt for reliable pressing of the cylindrical portion receiving hole tip side wall 9a, but may be larger than Δt for easy screwing. However, if it is too large, it will affect the rigidity of the tool, so it should be kept within 5 times Δt. When the clearance between the pin hole 11 of the throwaway tip and the cylindrical portion 10 of the fastening member 8 is 3 μm to 13 μm, the value of the eccentric amount Δt of the conical surface is 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 tightening member and the tool body will be excessive and may be damaged during use. Further, when the clearance between the pin hole 11 and the cylindrical portion 10 is increased, the positions of the male screw portion 5 and the conical receiving surface 4 must be changed in the direction toward the rear end of the tool body (in the direction of the tip seat bottom surface 12). The shape of the cylindrical portion receiving hole 9 is not limited to the long hole shape shown in FIG. 7, but may be any shape as long as the fastening member cylindrical portion lower end 10 b is constrained on the tool front end side and the tool outer peripheral side. In order to accurately position the throw-away tip, the present invention is more effective when combined with a shape in which the slit groove 13 is provided on the bottom surface of the tip seat as shown in FIG. This is because the clearance generated by the tolerance of the throw-away tip thickness and the groove width of the tip seat can eliminate the gap between the tip near the tip seat bottom surface and the side surface of the tip seat that occurs when the tip is fixed. Stable throwaway tip fixation is realized. Hereinafter, the present invention will be described in detail based on examples.
[0009]
【Example】
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, and the throwaway tip 2 is inserted into the tip seat 7, and the throwaway tip 2 is detachably fixed by a fastening member 8. The fastening member 8 was manufactured by managing with high accuracy such that the circumferential runout tolerance between the conical head portion 3 and the cylindrical portion 10 is 10 μm or less, and the radial tolerance of the cylindrical portion is also 10 μm or less.
FIG. 6 is a sectional view of the throwaway tip mounting holder. When the tightening member 8 is tightened, the conical receiving surface 4 corresponds to the conical head 3, and the cylindrical portion receiving hole 9 corresponds to the lower end 10 b of the tightening member cylindrical portion, and the conical receiving surface 4 extends toward the rear end of the tool body. The eccentric amount Δt (set to 40 μm in the present embodiment) exerts a force for pressing the pin hole 11 of the throwaway tip 2 with the cylindrical portion 10 and also exerts a force for pushing the throwaway tip 2 on the tip seat side surfaces 7a and 7b. To fix.
At this time, the cylindrical part lower end 10b is received by the cylindrical part receiving hole tip side wall 9a of the cylindrical part receiving hole 9, and there is no gap between the cylindrical part lower end 10b and the cylindrical part receiving hole 9 over approximately 1/2 circle. Become. For this reason, since the fastening member is restrained on the tool front end side and the tool outer peripheral side, the throwaway tip is firmly pressed against the bottom surface of the tip seat against loads from all directions.
At this time, the clearance of the cylindrical portion receiving hole 9 at the rear end side wall 9b of the cylindrical portion receiving hole was set to 0.1 mm, so that there was no inconvenience such as being caught when the fastening member was screwed.
[0010]
Although the present invention has been described with respect to a ball end mill, the present invention 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 having a convex V on the bottom surface of the throwaway tip, and FIG. 10 shows a plan view of a throwaway tip used therefor. FIG. 11 shows a plan view when applied to a square end mill, and FIG. 12 shows a plan view of a throwaway tip used in this case.
[0011]
【The invention's effect】
According to the present invention, the position of the tightening member is difficult to move even with loads of various directions and sizes during use of the tool, and the throwaway tip is stably pressed, so the tip mounting accuracy is high. It is possible to keep.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a conventional product 1. FIG.
FIG. 2 is a cross-sectional view of a main part of a conventional product 2. FIG.
FIG. 3 shows a front view of an embodiment of the present invention.
4 is a front view of a throwaway tip used in the embodiment shown in FIG. 3. FIG.
FIG. 5 shows a front view of a fastening member.
6 is a cross-sectional view of the main part in the fixed state of the throwaway tip of the embodiment shown in FIG. 3. FIG.
7 is a cross-sectional view taken along the line AA in FIG.
FIG. 8 is a cross-sectional view of the 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 throwaway tip used in the embodiment shown in FIG.
FIG. 11 shows a front view of another embodiment of the present invention.
12 is a front view of a throwaway tip used in the embodiment shown in FIG. 11. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tool main body 2 Throw away tip 3 Cone-shaped head 4 Cone-shaped receiving surface 5 Male thread part 6 Female thread part 7 Tip seat 7a, 7b Tip seat side surface 8 Clamping member 9 Cylindrical part receiving hole 9a Cylindrical part receiving hole front end side wall 9b Cylinder Side wall 10 of receiving part rear end side Clamping member cylindrical part 10a Clamping member cylindrical part upper end 10b Clamping member cylindrical part lower end 11 Pin hole 12 Chip seat bottom face 13 Slot groove Δt Eccentricity toward the tool body rear end direction

Claims (3)

In a throw-away type cutting tool in which a throw-away tip is sandwiched between a hollow tip seat provided in a slit shape at the tip of a tool body and fixed with a fastening member, the side surface of the tip seat of the tool body has a fastening member A conical receiving surface that is eccentric in the direction of the rear end of the tool body with respect to the center line of the fastening member is provided at a portion corresponding to the conical surface of the head, and a cylindrical portion receiving hole of the fastening member is provided on the other side surface of the tip seat. And the side wall and a female thread portion corresponding to the male thread portion of the fastening member connected to the side wall, the throwaway tip being fixed by the side surface portion of the tip seat, and the pin hole of the throwaway tip by the cylindrical portion of the fastening member performed by the pressure from the side surface toward the rear end of the tool body, and especially that it has a mounting reference surface is brought into contact with the cylindrical portion of the fastening member and the side wall of the cylindrical portion receiving hole Throw-away cutting tool to be.   The throw-away cutting tool according to claim 1, wherein the depth of the cylindrical portion receiving hole is 2 to 30% of the blade diameter.   3. The throw-away cutting tool according to claim 1, wherein the cylindrical portion receiving hole is a long hole extending in the tool axis direction.

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