JPS6149042B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a milling cutter, and particularly to a face milling cutter that achieves a balance between machinability and cutting resistance, and is capable of achieving high cutting speed with relatively low cutting resistance. Among face milling cutters used to cut a plane perpendicular to a milling cutter axis, particularly those with a large diameter are used with a cutting edge attached to the milling cutter body. This type of face milling cutter (hereinafter simply referred to as a "milling cutter") includes one with a brazed cutting edge (cutting tip), and a throw-away type with a removable attachment to the main body using screws or other attachment means. These formats are provided. In all of these milling cutters, the tip is attached to the main body at a predetermined angle (rake angle), and the setting of this angle greatly affects the performance of the milling cutter. The rake angle here is divided into the rake angle in the axial direction of the milling cutter (axial rake) and the rake angle in the radial direction of the milling cutter (radial rake). (positive) and negative (negative), and after specifically determining the positive and negative angles, this installation is carried out. Another important aspect of the cutting edge angle of a milling cutter is the corner angle, which is usually determined by the shape of the milling cutter body. Depending on the setting method of the axial rake and radial rake, face milling cutters are available in (1) negative type (radial negative, axial negative), (2) positive type (radial positive, axial positive), (3) negative type (combination of negative and positive). , radial positive, and axial negative). Among these, the negative type (1) has a large cutting resistance, but has the advantage of strong cutting edge strength.
Although the positive type (2) has low cutting resistance and good chip evacuation, it has the problem of weak cutting edge strength, and the negative type (3) has an intermediate performance between the two, such as radial, positive, In the case of axial/negative, the cutting resistance and edge strength are negative types,
The chip evacuation property is positive, but the performance tends to be unsatisfactory. In any case, the above-mentioned types of milling cutters all have the same axial rake and radial rake on the tips attached to the milling cutter body, so their advantages are fixed and their purpose of use tends to be limited. Ta. The object of the present invention is to eliminate the above-mentioned problems and provide a highly versatile face milling cutter. In short, this invention does not make the mounting angle of the axial rake and radial rake of the cutting tip fixed to the milling cutter body, but instead arranges negative and positive axial rake and radial rake, respectively, for one main body, thereby increasing the versatility of the milling cutter. It is an enhanced version of Embodiments of the present invention will be described below with reference to the drawings. In Figures 1 to 3, reference numeral 1 denotes a milling cutter body, which has a sloped surface with an angle δ so as to give a predetermined corner angle to the attached cutting tip, and the entire body has an approximately truncated conical shape. It's summery. A cutting tip 2 is attached to the milling cutter body with a bolt 3, and a recess into which the cutting tip is fitted is formed in the milling cutter body. This cutting tip has a triangular shape for reasons explained later. As shown in FIG. 2, the triangular cutting tip 2 has an independent recess into which one tip 2a is fitted and fixed, on a radius 5 shown in FIG. In another radius 5 adjacent to this at a constant angle γ, recesses into which the chips 2b and 2c are fitted are provided adjacently to form a recess set, and the individual recesses and the recess set are arranged alternately at equal angles. Form at intervals. In the case shown, the single chip 2a and the set of two chips are 8
Therefore, the angle γ formed by each radius 5 is
is approximately 45°. Note that the reference numeral 8 in the figure is a groove for discharging chips. Fig. 4 is an expanded view of the slope of the milling cutter body, and to explain the mounting angle of each chip using this figure, the radial rake α of the single chip 2a is
₁ is attached to be negative. Next, among the set of two chips, the radial rake _α2 of the chip 2b is positive, and the radial rake _α3 of the chip 2c is negative. A total of eight individual chips 2a and a set of chips 2b and 2c, each having a radial rake defined in this way, are arranged alternately on the slope of the milling cutter body. Note that arrow X indicates the rotation direction of the milling cutter. Of these, the radial rakes of each pair of chips 2b and 2c are positive and negative, respectively, so in the case of square chips, the arrangement interval W between both chips must be large, making it virtually impossible to mount them. Also, even if a square tip (number 6 in Figure 2) is installed, the radial rake is not set to 0, so
Compared to the triangular tip as shown in Fig. 5, the tail end 6
a largely protrudes from the outer surface of the milling cutter with a height h, increasing the cutting resistance. The reason for using a triangular chip in this invention is that, as mentioned above, a square chip cannot be used due to the large cutting resistance, but when each side of a triangular chip is used as a cutting edge, when one of the cutting edges becomes dull, it is difficult to use a fixing device. All you have to do is loosen it and turn the tip so that you can use the new edge (cutting edge) and fix it.Practically speaking, the shape with the largest number of edges is a triangle, and there are no other factors that increase the cutting resistance. It depends on that. Next, as mentioned earlier, there are three types of cutting chips: negative type, positive type, and negative-positive type, but it is possible to use only one type depending on the material properties of the object to be cut. However, in determining the combination arrangement, there is a condition that the milling cutter must be provided with a groove 8 for discharging chips for each chip. 6th for a constant machining width S
In the arrangement shown in the figure, the depth and number of grooves affect the strength of the milling cutter body, and the number of chips is naturally limited because the number of grooves and the groove 18 correspond to the overall width S. When comparing milling cutter bodies of the same diameter, it is not possible to install a large number of milling cutters as in the present invention. It goes without saying that the total number of chips in one milling cutter body directly affects the milling cutter's capacity and the time interval for replacing the chips. It is also possible to arrange two identical negative type chips as shown in Fig. 7, but the cutting waste discharge groove corresponds to the two chips, and the groove width P of the groove is larger and deeper than the amount of discharge chips. It must also be deep, which is less desirable than the strength of the milling cutter itself. However, in the present invention, when two different types of "positive negative" chips (2b, 2c) are arranged so that one side of the triangle is close to each other and parallel to each other, this allows the chips to be distributed in two directions, up and down in FIG. It can be made into a groove for discharging water, and the width of the groove can be made narrow. The tip 2a is of a normal "negative-positive" shape, and the uncut portion between the tips 2b and 2c is finished cut. Next, to explain the axial rake of each chip with reference to FIG. 3, the axial rake β ₁ of the single chip 2a is positive, the axial rake β ₂ of chip 2b of the two chip groups is negative, and the axial rake β ₃ of chip 2c is positive. . From the above, the radial rake and axial rake of each chip are as shown in the table below.

[Table] In the milling cutter having the above configuration, the two chips 2b and 2c, each having a different radial rake and axial rake, perform cutting, and the subsequent single chip 2a cuts the remaining portion of the cut by the aforementioned chip. Located on the virtual circumference 9 including the middle between the parallel bases of the chips 2b and 2c,
By alternately cutting with these individual chips and the two chip sets, good cutting can be achieved with less cutting resistance. By implementing this invention, the cutting blades on each side of the triangle can be effectively used by loosening the bolt 3 and turning the tip to switch the cutting blade, and by adopting the triangular tip, the h dimension in Fig. 5 can be reduced. In order to avoid unnecessary cutting resistance, the triangular chips are made of two types of ``negative-positive'' type chips, the cutting edge has appropriate strength, and chip evacuation is made in two directions for good results. , the combination of negative and positive types with intermediate performance between negative types and positive types can be highly versatile, and the combination of two chip sets and one single chip allows the number of chips to be attached to one milling cutter body to be increased, and The strength of the milling cutter body is also sufficient, and cutting performance can be improved by increasing the number of chips.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a milling cutter according to the present invention, with the cutting surface facing upward; Fig. 2 is a plan view of the milling cutter shown in Fig. 1; and Fig. 3 is a view taken along line A-A in Fig. 2. Figure 4 is a developed view of the slope of the milling cutter, Figure 5 is a sectional view taken along the line B-B in Figure 2, Figure 6 is a partial view of the arrangement when chips of the same type are arranged in three stages, FIG. 7 is a diagram showing that the groove width increases when the same type of chips are arranged so that the cutting edges are in line. 1... Milling cutter body, 2... Cutting tip, 2a
...Single chip, 2b, 2c...Chip group configuration chip, α ₁ , α ₂ , α ₃ ... Radial rake, β
₁ , β ₂ , β ₃ ...Axial rake.

Claims (1)

[Claims] 1. In a milling cutter body with a plurality of cutting tips attached to the slope of a trapezoidal cone, two triangular recesses are made with their bases close to each other and parallel to each other, and one of the vertices opposite the bases is on the top side of the trapezoidal cone. , the other forming a set of recesses with the bottom facing side, and having an angular distance from the set of recesses with respect to the radius in a plan view of the milling cutter body, and the substantially center of the triangle includes the midpoint between the parallel bases. Single triangular recesses located on the virtual circumference are provided, and the set of recesses and the single recesses are positioned alternately and at approximately equal angular intervals, and triangular chips are fixedly attached to these recesses. For the concave assembly, the triangular cutting tip 2c fixedly attached to the concave on the bottom side on the slope of the trapezoidal cone has a negative radial rake and a positive axial rake, and the triangular cutting tip 2b on the top side has a radial rake. A face milling cutter characterized in that the triangular cutting tip 2a, which has a positive rake and a negative axial rake, and is fixedly attached to a single recess, has respective recesses so that the radial rake is negative and the axial rake is positive. .