JPH0825087B2 - Throwaway type rolling tool - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [Industrial application] The present invention relates to a throwaway type rolling device in which a plurality of throwaway chips are fixed along a plurality of grooves having twists formed on the outer periphery of a tool body. It concerns a cutting tool.

[Prior Art] FIGS. 4 to 6 show a throwaway type end mill (hereinafter abbreviated as an end mill) which is an example of a conventional throwaway rolling tool (hereinafter abbreviated as a cutting tool) of this type. .), And reference numeral 1 in the drawing denotes an end mill body (tool body).

The end mill body 1 has a substantially columnar shape, and four grooves 2 having a twist along the axial direction are formed on the outer periphery of the tip end portion thereof at equal intervals in the circumferential direction. Here, the twist angles of these groove portions 2 ...
It has been. Further, a plurality of (2 to 3 in the figure) chip mounting seats 4 ... Are spaced from the tip end of the end mill main body 1 toward the base end on the wall surface 3 of each groove 2 facing the rotation direction at predetermined intervals. Is formed. Then, the throw-away chips 5 ... Are removably attached to the chip mounting seats 4 ... With the clamp screws 6.

These throw-away chips 5 ... are rectangular plate-like plates made of cemented carbide or the like whose upper and lower surfaces are parallel to each other, and the cutting blades 7 ... The cutting blades 7 ... Are attached so as to be continuous in the direction of the axis O of the end mill body 1 in the rotation locus.

In the above-described conventional end mill having the above-described structure, since the groove portions 2 are formed with a twist, the cutting blades 7 of the throwaway chips 5 ...
… Each bite on the work piece in sequence, and gradually move away from the work piece. Therefore, since the cutting load does not fluctuate rapidly, there is an advantage that the end mill main body 1 can be prevented from vibrating greatly.

[Problems to be Solved by the Invention] However, in the above-described conventional end mill, although a relatively large vibration due to a sudden change in the cutting load can be prevented, a relatively small vibration occurs. . Then, due to this small vibration, the cutting edge 7 of the throwaway chip 5 is damaged, and the finish surface is deteriorated particularly at the bottom surface of the workpiece to be cut by the bottom blade located at the tip of the end mill body 1. Therefore, it is difficult to say that it is sufficiently satisfactory when high surface roughness is required, heavy cutting (deep cutting), or high feed cutting.

[Investigation of Cause of Problem] Then, as a result of investigating the cause of the comparatively small vibration in the rolling tool of this type, the inventor of this application obtains the cause as follows. Came to.

That is, in the above-mentioned conventional end mill, since the twist angles θ of the groove portions 2 are equal to each other and the groove portions 2 are formed at equal intervals in the circumferential direction, they are mounted in the groove portions 2 as shown in FIG. The circumferential distance from the cutting edge 7 of the throwaway chip 5 to the cutting edge 7 of the throwaway chip 5 mounted in the adjacent groove portion 2 is constant. When a cutting load is applied to the throwaway chips 5 of each groove 2 having a constant interval, the vibration of the end mill body 1 caused by the cutting load also has a substantially constant frequency, and this vibration It has been estimated that they resonate with each other and generate small vibrations in the end mill body 1, but to a degree that adversely affects the surface roughness.

[Object of the Invention] The present invention has been made based on the above estimation, and it is possible to prevent relatively small vibrations from occurring in the tool body, thereby improving the finished surface and performing heavy cutting (deep cutting). It is an object of the present invention to provide a rolling tool that enables high-feed cutting.

[Means for Solving Problems] According to the present invention, a plurality of groove portions having twists are formed on the outer periphery of a tool body, and a plurality of throw-away tips having cutting edges are fixed along the respective groove portions. In the throw-away type rolling tool, the plurality of groove portions are arranged at equal intervals in the circumferential direction at the tip of the tool body, and the twist angle of at least one of these groove portions is the twist angle of the other groove portion. On the other hand, the throw-away tips are mounted with the same rake angle.

[Operation] The circumferential distance between the cutting edge of the throwaway chip mounted in the groove set to have a different twist angle and the cutting edge of the throwaway chip mounted in the groove adjacent to this changes. As a result, the frequency of vibration generated in the tool body changes irregularly as the end mill rotates,
The tool body does not resonate with these vibrations. Therefore, it is possible to prevent vibration that would deteriorate the finished surface of the tool body.

Further, since these groove portions are arranged at equal intervals in the circumferential direction at the tip of the tool body, while the twist angles of the groove portions are set to different angles as described above, the groove width is extremely wide and narrow. It is possible to prevent the occurrence of damage, which can prevent a situation in which the chip discharging property is hindered.

Furthermore, even though the twist angles of the grooves are different in this way, the throw-away tips mounted along this groove have the same rake angle, so the rake angle can be cut regardless of the twist angle of the groove. The most suitable angle can be set, and the tip mounting seat for mounting the throw-away tip can be easily formed.

[Embodiment] FIGS. 1 to 3 show an end mill which is an embodiment of the rolling tool of the present invention, and the same reference numerals are given to the same parts as those shown in FIGS. 7 to 9. Is attached.

1 to 3, in this end mill, four groove portions 12, 13, 14, 15 having a twist are formed on the outer periphery of the tip end portion of an end mill body (tool body) 11. Then, of these four groove portions 12 to 15, the rotation axis O
The twist angle of the two groove parts 12 and 14 which are sandwiched between
Is a _1, the helix angle of the other two grooves 13 and 15 are somewhat larger angle theta ₂ than the helix angle theta _1. As shown in FIG. 2, these four groove portions 12 to 15 are arranged at equal intervals in the circumferential direction at the tip of the end mill body 11, but the twist angles θ ₁ and θ ₂ are set to different angles. Therefore, they are formed at unequal intervals in the circumferential direction at positions other than the tip of the end mill body 11.

Then, the throw-away chips 5 ... Are removably attached to the chip mounting seats 4 ... Formed in the grooves 12 to 15 with the same rake angle α.

In the end mill having the above structure, however, the twist angle θ ₁ of the two groove portions 12 and 14 is made smaller than the twist angle θ ₂ of the other two groove portions 13 and 15, as shown in FIG. The circumferential distances between the groove portions 12 and 13 and between the groove portions 14 and 15 gradually increase from the tip of the end mill body 11 toward the base end side, and between the groove portions 13 and 14 and the groove portions.
The distance between 15 and 12 becomes progressively narrower. Therefore, the circumferential distances of the throw-away tips 5 mounted along the respective groove portions 12 to 15 are also from the distal end of the end mill main body 11 to the base end side between the throw-away tips 5 mounted on the adjacent groove portions. It changes as it goes, and as a result, the frequency of the minute vibration generated by each throw-away tip 5 ... Cutting the work changes along the axial direction. As a result, the vibration caused in the end mill body 11 by the cutting of the throwaway tip 5 ... becomes irregular in the axial direction, resulting in the cutting of the cutting edge 7 in the end mill body 11 or the machining of the workpiece. It is possible to prevent the occurrence of co-vibration that deteriorates the finished surface roughness of the bottom surface of the object.

By the way, the reason why the twist angles θ ₁ and θ ₂ of the groove portions 12 and 14 and the groove portions 13 and 15 are different from each other as described above is that the interval between the groove portions 12 to 15 is changed, whereby the end mill body 11 is changed. This is to prevent co-vibration from occurring.
Therefore, the vibration prevention effect can be exerted as the rate of change in the interval between the groove portions 12 to 15 increases. To increase the rate of change, the difference between the twist angles θ ₁ and θ ₂ may be increased.

On the other hand, however, if the twist angles θ ₁ and θ ₂ are set to have different magnitudes, the gap between the groove portions 12 to 15 varies widely. If the width of the end mill body 11 on the base end side becomes excessively narrow, it becomes difficult to discharge chips.

However, on the other hand, in the end mill with the above configuration,
Grooves 12 and 14 and groove 1 having different twist angles θ ₁ and θ ₂
Since 3 and 15 are arranged at equal intervals in the circumferential direction at the tip of the end mill body 11, for example, these groove portions 12
It is possible to prevent the extreme wideness between the groove portions 12 to 15 as compared with the case where the grooves 15 to 15 are randomly arranged so as to be unequally spaced in any portion. And
As a result, a sufficient groove width is secured even on the base end side of the end mill main body 11, a situation in which the dischargeability of chips is impaired is prevented, and smooth and favorable chip disposal can be performed. It will be.

From the above viewpoint, it is preferable that the difference between the twist angles θ ₁ and θ ₂ be as large as possible within a range in which any of the groove portions 12 to 15 is not excessively narrowed. Specifically, in an end mill having four grooves, if the diameter D is about 32 mm and the length of the blade 12 is within 2D,
It is desirable that | θ ₁ −θ ₂ | = 1 ° to 10 °.

On the other hand, in the present embodiment, the groove portions 12 and 14 are set to different twist angles θ ₁ and θ ₂ as described above, while the throw-away tip mounted along the groove portions 12 and 14 is set. The rake angles .alpha. Are equal to each other. Therefore, according to this embodiment,
While the groove portions 12 and 14 having different twist angles θ ₁ and θ ₂ exert the above-described vibration preventing effect, the throw-away tip 5 is provided regardless of the difference in the twist angles θ ₁ and θ _2.
... It can be installed so that it has a rake angle α most suitable for cutting, and the rake angle is constrained by the helix angle of the groove, which causes an increase in cutting resistance with some throwaway tips. Can be prevented. Further, when forming the tip mounting seats 4 on which the throw-away tips 5 are mounted on the end mill main body 11, in the present embodiment, the axis O, the tip surface, etc., which are the basis of the design and processing of the end mill main body 11, are formed. It suffices if the tip mounting seats 4 are formed with the same inclination with respect to each other, and as a result, the advantage that the end mill main body 11 is easily manufactured can be obtained.

In each of the end mills of the above-described embodiments, four grooves 12 to 15 are formed in the end mill body 11, but the number of grooves is not limited to four as long as it is plural. Further, two of the four groove portions have the same twist angle, and the twist angles are alternately large and small, but the twist angles of all the groove portions 12 to 15 may be different from each other, or different from each other. The groove portion having the twist angle may be sequentially formed in the circumferential direction from the one having the smaller twist angle. In any case, in the present invention, the plurality of groove portions are arranged at equal intervals in the circumferential direction at the tip of the tool body, and the twist angle of at least one groove portion of the plurality of groove portions is set to the twist angle of the other. However, the rake angles of the throw-away tips may be set to be equal to each other.

Further, the present invention is not limited to the end mill, but can be applied to other milling tools such as a flat milling cutter and a side milling cutter.

As described above, according to the rolling tool of the present invention,
Since the twist angle of at least one groove portion of the plurality of groove portions to which the throw-away chip is mounted is set to an angle different from the twist angle of the other groove portions, the gap between the one groove portion and the groove portion adjacent thereto is set. The circumferential distance of the tool changes from the tip of the tool body toward the base side, and as a result, the frequency of vibration generated in the tool body becomes irregular, so the cutting edge of the throwaway tip It is possible to prevent co-vibration that may cause chipping or worsen the finished surface at the bottom of the work piece, and especially in heavy cutting (deep cutting), a remarkable effect from low feed to high feed can be obtained. Also, it is possible to obtain the effect that the required power can be reduced.

Moreover, since the plurality of groove portions are arranged at equal intervals in the circumferential direction at the tip of the tool body, while exhibiting such an excellent effect, it is possible to prevent an extremely wide width between these groove portions. As a result, it is possible to prevent problems such as chip discharge and maintain good chip disposability.

Furthermore, even though the twist angles of the grooves are different in this way, the indexable inserts mounted along the grooves have the same rake angle, so the optimum rake angle for cutting is set for all indexable inserts. Therefore, it is possible to prevent the situation where the cutting resistance is partially increased, and the tool body can be easily designed and manufactured.

[Brief description of drawings]

1 to 3 show one embodiment of the rolling tool of the present invention. FIG. 1 is a side view, FIG. 2 is a front view, FIG. 3 is a side development view, and FIGS. FIG. 6 shows a conventional rolling tool, FIG. 4 is a side view, FIG. 5 is a front view, and FIG. 6 is a side development view. 11 …… End mill body, 12,13,14,15 …… Grooves θ ₁ , θ ₂ …… Twist angle.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Arai 1-27-20 Nishishinagawa, Shinagawa-ku, Tokyo Mitsubishi Metals Co., Ltd. Tokyo Works (72) Innovator Nobuo Hiyama Izumi, 4-1,846 Imamiya, Utsunomiya City, Tochigi Prefecture Sangyo Co., Ltd. (56) References Japanese Patent Publication Sho 30-5244 (JP, B1)

Claims (1)

[Claims] 1. A throw-away type milling tool, wherein a plurality of grooves having twists are formed on the outer periphery of a tool body, and a plurality of throw-away tips having cutting edges are fixed along the grooves, respectively. While arranging a plurality of groove portions at equal intervals in the circumferential direction at the tip of the tool body, while setting the twist angle of at least one groove portion of these groove portions to an angle different from the twist angle of the other groove portions,
The throw-away tip is a throw-away type milling tool, wherein the inserts are attached with the same rake angle.