JPS6240728Y2 - - Google Patents

Description

[Detailed explanation of the idea] (b) Industrial application fields This invention relates to a solid carbide end mill.

(b) Conventional technology and its problems Conventional solid end mills are as shown in Figures 1 and 2.
As shown in the figure, the web thickness (core thickness) W of the main body 1 is uniform up to the end of the peripheral cutting edge 2, but from the viewpoint of wear resistance, the solid end mill uses cemented carbide as the material. If this structure is adopted especially for long blades, the rigidity of the cutting part will be insufficient because cemented carbide has inferior transverse rupture strength compared to high-speed steel, etc. Therefore, the end mill is very likely to break when subjected to force in the bending direction.

Therefore, as a countermeasure, conventionally, when using cemented carbide as the material, the web thickness W was adjusted to be equal to the outer diameter D.
It is thicker (approximately 0.6D) than a high-speed steel end mill, which is 0.4 to 0.5 times thicker, but it is natural that if the web thickness is increased in an end mill of a given diameter, the chip discharge groove 3 will become shallower. It is true,
As a result, chip evacuation becomes poor, and in extreme cases, the end mill breaks due to excessive load due to chip clogging.

(c) Means for solving the problem In order to reduce breakage accidents of solid carbide long blade end mills, this invention solves the contradictory problems mentioned above by adding a web taper.
This problem was solved by sloping the web portion so that the core thickness of the end mill is thinner at the tip and gradually thickens toward the rear.

Here, for the purpose of centripetal force when axially thrusting into the work material and countermeasures against chip clogging at a part of the tip,
Conventionally, only the tip of the web is tapered, but generally the total length of the outer cutting edge is 3.
If a configuration similar to that of a ~4D long-flute end mill is adopted, there will be a problem with breakage resistance when using the peripheral blade in transverse feed in the length range beyond the web taper part.

Therefore, in this invention, the position of the web taper and the thickness of the web are adjusted as described in the examples below to balance the rigidity to withstand the lateral load and the chip evacuation performance.

(d) Examples The details of this invention will be explained below based on the examples shown in the attached FIGS. 3 to 5.

The end mill 10 shown in the figure shows an example of application to a two-flute end mill, and the web thickness from the tip of the main body 11 made of cemented carbide to near the end of the peripheral cutting edge 12, strictly speaking, is as follows: The web thickness in the range from the tip to the rising point of the chip discharge groove 13 is
It gradually becomes thicker toward the rear with a slope of W ₁ −W ₀ /. The thickness of the web is determined by setting W ₀ at the tip shown in Figs. 3 and 4 to about 0.4 to 0.6D (D is the end mill diameter), and W ₁ at the rising point of the chip discharge groove 13 shown in Fig. 3 to 0.6. Set it at ~0.8D. By doing this, you can achieve the purpose of your idea.

That is, when the flow direction of the chips is in the longitudinal direction of the groove 13, the chips are smoothly discharged even if the groove 13 is somewhat shallow. However, chips immediately generated from the cutting edge flow diagonally backward toward the rotation center of the end mill, and if this flow is not smooth, chip clogging will occur. On the other hand, when an end mill is fed vertically like a drill, the parts that contribute to cutting are mainly the bottom cutting edge (tip permanent cutting edge) 14 and the tip of the outer cutting edge 12, and the rear part of the outer cutting edge mainly acts as a burnishing agent. to do. In other words, it can be said that the direction of flow of chips differs from the length direction of the groove almost only at the tip of the main body. Therefore, if the chip discharge groove near the bottom cutting edge is made deep enough and space is secured to change the direction of the chips flowing toward the center of rotation, even if the groove 13 becomes a little shallow at the rear end of the outer peripheral cutting edge, the chips will still flow. does not worsen the discharge performance. Regarding this point, a similar effect can be obtained with a conventional end mill in which only the tip of the web is tapered, but the situation changes when the groove depth during vertical feeding exceeds the web taper, and chips become easily clogged. In addition, there is less worry about chip clogging in cross-feed processing, but in this case, the stress applied to the bending is very large, so a thin web with a large taper slope may break. On the other hand, according to this invention, the slope of the web is uniform and small throughout, ensuring the overall bending stiffness and groove depth at the rear, so such problems do not occur. Furthermore, the end mill itself becomes more rigid as the web thickness gradually increases toward the rear. Therefore, breakage of the end mill can be prevented from both of the viewpoints of not clogging with chips and applying an excessive load to the main body, and increasing the strength of the web.

Note that long-blade end mills generally have a spiral outer cutting edge in order to prevent chatter during cutting, but for convenience, Figures 1 and 3 show the outer periphery in a spiral shape. The cutting edge and chip evacuation groove are shown expanded. However, this idea does not matter whether the blade is a straight blade or a spiral blade. Furthermore, the number of blades is not limited to two.

(e) Effects As explained above, the carbide end mill of this invention increases the strength of the main body without deteriorating the chip evacuation performance by gradually increasing the web thickness toward the rear. Breakage accidents can be greatly reduced.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of a conventional solid end mill, Fig. 2 is a front view thereof, Fig. 3 is a partially cutaway side view showing an example of the end mill of this invention, and Fig. 4 is a partially cutaway side view of a conventional solid end mill.
The figure is a front view thereof, and FIG. 5 is a sectional view taken along the - line in FIG. 3. 10...End mill, 11...Main body, 12...
Peripheral cutting edge, 13...Chip discharge groove, 14...Bottom blade.

Claims (1)

[Scope of utility model registration request] In a solid long blade end mill made of cemented carbide, the web is sloped in the range from its tip to the final rising point of the chip discharge groove,
A solid carbide end mill characterized in that the web thickness is gradually increased from the tip toward the rear so that when the end mill diameter is D, the web thickness is 0.4 to 0.6D at the tip and 0.6 to 0.8D at the above rising point.