JPH0448882Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Field of Industrial Application) The present invention relates to an improvement of a cutting tool having a nose near the top as a cutting edge. (Prior Art) Conventionally, as this type of cutting tool, for example, as disclosed in Japanese Utility Model Application No. 60-91302,
It is known that the nose near the top of the throw-away tip is composed of a cutting edge nose part forming the tip side and a cutting edge nose part continuous to the cutting edge nose part forming the base end side. . In this case, the nose radius of the blade base nose portion is 5.
~20mm, the arc depth is set to 0.03~0.05mm, and in particular, the nose radius of the blade tip is set to 5~20mm.
By setting the nose radius to 20 mm, which is much larger than the general nose radius of 0.2 to 1.6 mm, it is possible to improve machining accuracy and machining efficiency. (Problems to be solved by the invention) By the way, in the above-mentioned conventional tool, no specific numerical values are listed for the nose radius of the cutting edge nose portion, and judging from the drawings published in the above-mentioned gazette, It can be estimated that it is set at approximately 0.2 to 0.8 mm. However, if the nose radius of the cutting edge nose section is large as described above, there is a risk that the tool will not bite into the workpiece during cutting, resulting in a situation where the machined surface cannot be cut perfectly circularly or straight. . The present invention was developed in view of the above, and its purpose is to improve the bite of the workpiece during cutting by improving the shape of the nose that constitutes the cutting edge. The object of the present invention is to reliably obtain the roundness and straightness of the machined surface, and to further improve the machining accuracy while improving the machining efficiency. (Means for Solving the Problems) In order to achieve the above object, the solution of the present invention is to replace the nose of a cutting tool whose cutting edge is the nose near the top with a cutting edge nose portion constituting the tip side. and a blade base nose portion that is continuous with the blade nose portion and constitutes the proximal end side. In this case, the nose radius of the above-mentioned cutting edge nose part is set to 0.1 to 0.15 mm, and the nose radius of the above-mentioned cutting edge nose part is set to 4 to 0.15 mm.
6mm, the arc length to 1.8 to 2.5mm, and the arc depth to
Set each to 0.065 to 0.2 mm. (Function) With the above configuration, in the present invention, the nose radius of the cutting edge nose part, among the noses near the top, is 0.1
Since it is set to ~0.15mm, the bite when cutting the workpiece is good, ensuring the roundness and straightness of the machined surface, and further improving the machining accuracy. Become. Furthermore, the nose radius of the blade nose part is 4 to 6.
Since the diameter is set larger than the general ones (0.2 to 1.6 mm), it is possible to improve machining efficiency. (Example) Hereinafter, an example of the present invention will be described based on the drawings. 1 to 4 show a nose 1 portion near the top of the cutting blades 4, 4 of a cutting tool (such as a cutting tool) according to an embodiment of the present invention.
The blade is composed of a cutting edge nose portion 2 constituting the distal end side and a cutting edge nose portion 3 continuing from the cutting edge nose portion 2 and forming the proximal end side. As a feature of the present invention, the cutting edge nose portion 2 of the nose 1 has a nose radius R ₁ of 0.1 to 0.15 mm.
is set to . In this way, the cutting edge nose part 2
The reason why the nose radius _R1 of is set to 0.1~0.15mm is as follows.
If it is less than 0.1 mm, stress concentration on the cutting edge will deteriorate fracture resistance and chipping will occur early.
If it exceeds 0.15 mm, the above-mentioned chipping problem will be solved, but the increase in thrust force due to the increase in cutting resistance will result in poor biting of the workpiece during cutting, making it difficult to cut the machined surface into a perfect circle. Otherwise, there is a possibility that straight cutting cannot be performed. In addition, the blade base nose portion 3 of the nose 1 has a nose radius R ₂ of 4 to 6 mm and an arc length l of 1.8 to 2.5 mm.
The arc depth h is set to 0.065 to 0.2 mm, respectively. The reason why the nose radius R ₂ of the blade nose portion 3 is set to 4 to 6 mm is that if it is less than 4 mm, the cutting finish of the machined surface of the workpiece will deteriorate and at the same time the feed rate cannot be increased, so the machining efficiency will be reduced. On the other hand, if it exceeds 6 mm, the arc depth h becomes smaller and the flexibility when installing tools becomes worse. In other words, if the arc depth h becomes smaller, the depth of cut will change significantly, for example in the case of a cutting tool that uses a throw-away tip, etc., if the tip is not properly attached to the shank (body). This is because it is undesirable because it causes problems and requires a long time for adjustment. Furthermore, the arc length l of the blade nose part 3 is 1.8~
The reason for setting it to 2.5 mm is that if it is less than 1.8 mm, the amount of cutting will decrease, so the feed pitch must be made smaller, which will reduce the cutting efficiency, while if it exceeds 2.5 mm, the cutting force will increase. If the nose radius R increases, as in the case of the above-mentioned nose radius R ₁ , the biting of the workpiece during cutting may become worse, and the machined surface may not be able to be cut into a perfect circle or cut straight. It is. In addition, the arc depth h of the blade nose part 3 should be set to 0.065~
The reason for setting it to 0.2 mm is as follows. That is, if the arc length l of the blade nose 3 and the chord length are considered to be approximately equal in this case, the arc depth h is automatically determined by the following formula, and the set value of the nose radius R ₂ is added to this formula. By applying the set value of the arc length l to the set value of the arc length l, the above range is obtained. h=R ₂ −√ ₂ ² −(2) ^2The angles θ ₁ , θ ₂ , θ 3 formed by the cutting edges 4, 4 and the flank surfaces 5, ₅ are determined by the presence or absence of hardening of the machined surface of the workpiece, etc. It can be set as appropriate depending on the processing conditions. Next, we will demonstrate that it is desirable that the nose radius _R1 of the blade nose portion 2, which has the greatest influence on the machining accuracy and machining efficiency of the workpiece, is set to 0.1 to 0.15 mm as described above. I did a lot of testing. The test data at that time is shown in Table 1 below. The test procedure is to set the cutting speed V to 80m/
lifter valve (SCrL15:
The inner peripheral surface of HRC61-63) is machined. Further, the nose radius R ₂ at this time was set to 4 mm.

[Table] As is clear from this test data, when the nose radius R ₁ was 0.1 mm and 0.15 mm, good results were obtained with almost no difference in roundness and straightness. When ₁ is 0.2 mm, both roundness and straightness deteriorate rapidly, and the nose radius
It can be seen that when R ₁ is 0.05 mm, the number of machining is 19, which is extremely small compared to other cases. Further, the relationship between the nose radius _R1 and the cutting resistance at this time is shown in FIG. In the same figure, those marked with a ● mark represent back force, and those marked with an ○ mark represent principal force. Further, the broken line indicates the limit of occurrence of chatter surface. As is clear from this data, the cutting force increases rapidly when the nose radius R ₁ exceeds 0.4 mm. Furthermore, the relationship between the nose radius R ₁ and the number of processes at this time is shown in FIG. In the figure, the shaded areas represent the number of chattering surfaces. As is clear from this data, the number of machining increases as the nose radius _R1
It can be seen that when it exceeds 0.1 mm, it increases rapidly. In addition, the number of chattering surfaces generated is 5Kgf when the cutting force is
It can be seen that the number increases rapidly when the number exceeds this value. Therefore, it can be seen from the above test data that it is desirable to set the values of both nose radii R ₁ , R ₂ , arc depth h, and arc length l within the above-mentioned ranges. (Effects of the invention) As explained above, according to the invention, the nose radius of the nose portion of the cutting edge is set to 0.1 to 0.15 mm, which improves chipping resistance and extends the life of the tool. Moreover, the biting of the workpiece during cutting is improved, and the roundness and straightness of the machined surface can be reliably obtained, thereby further improving the machining accuracy. Furthermore, the nose radius of the blade nose part is 4 to 6.
mm, it is also possible to improve processing efficiency.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the nose portion of a cutting tool according to an embodiment of the present invention, and FIGS. 2 and 3 are arrows when the cutting tool is viewed from the arrow A direction and arrow B direction in FIG. Fig. 4 is a sectional view taken along line C-C in Fig. 1, Fig. 5 is test data showing the relationship between the nose radius of the cutting edge nose and cutting resistance, and Fig. 6 is the nose radius of the cutting edge nose. This is test data showing the relationship between and the number of machining operations. 1...Nose, 2...Blade tip nose part, 3...Blade base nose part, 4...Cutting edge, _R1 , _R2 ...Nose radius, l...Circular arc length, h...Circular arc depth.

Claims (1)

[Scope of utility model registration request] A cutting tool having a nose near the top as a cutting edge, wherein the nose consists of a cutting edge nose portion forming a tip side and a cutting edge nose portion forming a base end side continuous to the cutting edge nose portion. The nose radius of the cutting edge nose part is set to 0.1 to 0.15 mm, and the nose radius of the cutting edge nose part is set to 4 to 6 mm, the arc length is set to 1.8 to 2.5 mm, and the arc depth is set to 0.065 to 0.065 mm. 0.2mm
A cutting tool characterized by each of the following settings.