JPH0426162Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a throw-away cutting tool mainly used for deep groove machining, parting machining, etc.

[Conventional technology]

An example of a technique in which the cutting edge of a cutting tool used for the above-mentioned machining is formed with a throw-away tip to enable repeated use of the holder is disclosed in Japanese Patent Application Laid-open No. 1986-
There is one shown in No. 156124.

Since it is impossible to secure a very small throw-away chip to a thin holder using a well-known clamping mechanism, this tool uses a wedge that expands outward to create an upper and lower jaw in the holder. The throw-away tip is provided with a groove and a wedge portion on the opposite side of the cutting edge, and the wedge portion of the tip is held in place by utilizing the elasticity of the material of the holder.

In addition, since conventional cutting tools of this type use special steel for the holder material, the opening phenomenon of the wedge groove may occur during machining, causing the chip to shift, or
So-called chatter may occur. Therefore, as a solution to these problems, the present applicant previously proposed that at least the chip holding portion of the holder be made of cemented carbide.

In addition, since cemented carbide has a high Young's modulus and is difficult to deform, using it for the chip holding part caused new problems such as a decrease in the clamping force of the chip and the occurrence of cracks on the back end surface of the wedge groove. A number of other solutions were also proposed. The application number is listed below. Jitsugan No. 62-77599, No. 62-77600, No. 62
-77601, 62-186912, 62-186913.

[The problem that the idea aims to solve]

In order to eliminate the shift of the chip in the blade width direction and to provide centripetal properties, the wedge grooves and wedge surfaces of the wedge portion are designed such that one side has a V protrusion and the other side has a V protrusion.
A method of forming a groove and V-fitting is generally adopted.

Figure 3 shows a cross section of the fitting part of the tool before improvement.
In the figure, 3 is a wedge surface on the lower jaw side of the holder, 4 is a wedge surface on the upper jaw side, 13 and 14 are wedge surfaces of the wedge portion of the tip, and 5 is a contact surface where 3 and 13 touch each other.

Now, it is naturally desirable that the width a between the contact surfaces 5 and 5 in FIG. 3 be made wide from the standpoint of stably holding the chip without wobbling. Therefore, normally, the angle of the V-shaped protrusion 3 is made somewhat larger than the angle of the V-groove 13 to form the contact surface 5 at the outermost end of the V-groove. However, it was found that the tool in which a was increased caused the chip to crack C and break as shown in the figure.

Therefore, the purpose of this invention is to solve this problem of chip damage.

[Means to solve the problem]

This invention is based on the above-mentioned tool in which the wedge groove and the wedge surface of the wedge part are V-fitted with one side as a V projection and the other side as a V groove, as shown in Fig. 1. The angle θ ₂ of V and the angle θ ₁ of V of the V protrusion are set to the relationship of 3°≦θ ₂ /2−θ ₁ /2=θ,
Furthermore, the purpose of the V protrusion on the lower jaw side is achieved by removing the apex part so that the width a between the contact surfaces with the V groove is a≦0.4W with respect to the blade width W of the tip. It is.

In addition, more preferable numerical values of θ ₁ , θ ₂ and a are as follows: 3°<θ ₂ /2−θ ₁ /2<10° 0.1W<a<0.4W.

Also, the angle θ ₂ ′ of the V groove on the upper jaw side of the holder
The angle θ ₁ ' of the V of the V protrusion is not subject to as large a force as it is on the lower jaw side, so even if the width between the contact surfaces is wide, it will not lead to chip damage, and therefore there is no particular restriction on the angle. However, considering that the wider the width between the contact surfaces, the more stable the chip is held, it is desirable to set the relationship θ ₁ ′>θ ₂ ′, which maximizes the width.

[Effect]

The state of stress acting on the chip depends on the value of a. For example, b to e in FIG. 4 indicate that the cutting speed V=
Under the conditions of 150m/min, feed f = 0.4mm/rev,
When cutting S45C workpiece material with a 3mm width chip (the principal force at this time is 300Kg), the a of chip 10 is
Figure A-A' shows the results of stress generated at the cross-section section obtained by FEM analysis (finite element method analysis). A tensile stress indicated by a solid line arrow strongly acts on the chip 10 at the center, and as the value a becomes smaller, the stress changes to a compressive stress indicated by a dotted line arrow. The carbide material used for the throw-away chip is weaker against tensile force than compressive force, and therefore, from the above analysis results, it can be seen that keeping the value of a below a certain range is effective in preventing chip damage.

In addition, regarding the angle difference θ (=θ ₂ −θ ₁ /2) considered for the left and right halves of the V between the V groove and the V protrusion on the lower jaw side, Fig. 5 shows the FEM analysis of the displacement. It can be seen that if it is not made larger than this, the width of a will change due to the influence of displacement near the contact surface. Changes in a during cutting destabilize the state of stress acting on the chip, contributing to chip breakage. This is clearly shown in the experimental results below.

That is, in order to find appropriate values for a and θ, the inventor conducted cutting experiments by changing these values.
Figure 6 shows the results. This result clearly shows that in order to achieve the purpose of this invention, it is essential to satisfy the conditions of a≦0.4W and θ≧3°.

〔Example〕

FIG. 2 shows an embodiment of this invention.

In the figure, 1 is a holder made of cemented carbide or the like, 2 is a wedge groove provided in the head portion of 1, and 3 and 4 are wedge surfaces of the wedge groove. Reference numeral 6 denotes a surface from which the apex corner of the surface 3 formed on the V projection is removed, and both ends of this surface 6 become the contact surfaces 5 with the corresponding wedge grooves.

Reference numeral 10 denotes a throw-away tip having a cutting edge 11, and a wedge portion 12 corresponding to the wedge groove 2 is provided at the rear portion thereof. 13 and 14 are respective wedge surfaces of the wedge portion 12, both of which are formed in a V-groove. The exemplary tool has these surfaces 13,
14 is held between 3 and 4, and the chip 10 is placed in place.
Surface 3 receives the main component during cutting, and surface 4 receives the backing force.

The cross section of the fitting portion between the holder 1 and the chip 10 is the same as that shown in FIG. 1 because θ ₁ , θ ₂ , θ ₁ ', θ ₂ ' and a satisfy the conditions described above.

20 is a tool block that supports the holder 1. Since the tool block 20 is tapered fitted to the holder, the holder can be held accurately and stably, but any support member for the holder may be used.

Next, the V-fitting between 3 and 13 may be performed by using 3 as a V groove and 13 as a V protrusion with the apex angle removed. In this case, if the holder is made of a superhard material, damage to the holder can be prevented by the invention.

In addition, this idea does not particularly care about which of the wedge surfaces on the holder side and the tip side should be made into V-protrusions or V-grooves; therefore, it is possible to reverse the relationship between the concave and convex portions of 4 and 14 as shown in the diagram. It will be done.

[Effects] As described above, the cutting tool of this invention is able to properly set the V angle between the V protrusion and the V groove on the lower jaw side of the holder and the width between the abutment surfaces, and to cut the wedge surface of the V protrusion on the side where the wedge surface is formed. Since the tensile stress that acts on the part during cutting is reduced, damage caused by the cutting force of the throw-away tip or the holder made of carbide material is eliminated, allowing for economical use of the tool.
The effect is that stable cutting without interruption becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the fitting part of the tip and holder in the tool of this invention, Fig. 2 is a perspective view of the tool of the embodiment, Fig. 3 is a sectional view of the fitting part of the conventional tool, and Fig. 4. Figure a is a side view showing the analysis points of the FEM analysis, b to e in the same figure are diagrams showing the analysis results, Figure 5 is an FEM analysis diagram of the displacement of the contact surface, and Figure 6 is the width between the contact surfaces and V It is a figure which shows the result of the cutting experiment which changed the angle difference of a protrusion and a V groove|channel. 1... Holder, 2... Wedge groove, 3, 4... Wedge surface, 5... Contact surface, 6... Vertical angle removal surface, 1
0... Throwaway tip, 11... Cutting blade, 1
2... Wedge part, 13, 14... Wedge surface, θ ₁ ,
θ ₁ ′...V angle of V groove, θ ₂ , θ ₂ ′...V of V protrusion
angle, a...width between contact surfaces, W...cutting edge width.

Claims (1)

[Claims for Utility Model Registration] (1) The holder is provided with an outwardly expanding wedge groove, and the throw-away tip is provided with a wedge portion corresponding to the wedge groove on the side opposite to the cutting edge, and this wedge portion is connected to the wedge. In a cutting tool that utilizes the elasticity of the material of the holder to hold the holder in the groove, and that the wedge groove and the wedge surface of the wedge part have a V projection on one side and a V groove on the other side when viewed from the end, and are V-fitted, the bottom of the holder is When the angle θ ₂ of the V of the V groove on the jaw side and the angle θ ₁ of the V of the V protrusion are θ ₂ −θ ₁ /2=θ, set the relationship so that θ is maintained within the range of 3 to 10 degrees. Furthermore, the V protrusion on the lower jaw side is characterized by removing the apex part so that the width a between the contact surfaces with the V groove is 0.1W<a<0.4W with respect to the blade width W of the tip. Throw-away cutting tool. (2) V angle θ ₂ ′ of the V groove on the upper jaw side of the above holder
The indexable cutting tool according to claim 1, wherein the angle θ ₁ ′ of the V of the V protrusion and the V of the V protrusion are determined to satisfy θ ₂ ′<θ ₁ ′.