JPH0544006Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a throw-away ball end mill suitable for machining molds, and has been improved so that the effective cutting edge length in the axial direction can be set relatively large. This relates to a throw-away ball end mill.

(Conventional technology) In recent years, throw-away ball end mills have
Due to the demand for sharing cutting duties with the cutting blade tip, split blade types are becoming more common, and such types are disclosed, for example, in Japanese Utility Model Application Publication No. 181310/1983. The device disclosed in this publication has one center edge tip and two peripheral edge tips, the center edge tip is made of cemented carbide, and the cutting edge portion of the outer edge tip is made of ultra-high pressure sintered material. has been done.

(Problems to be Solved by the Invention) In the ball end mill disclosed in the above-mentioned publication, the effective length of the cutting edge in the direction of the central axis of the main body is approximately equal to the diameter of the cutting edge. However, depending on the shape of the workpiece, it is necessary to increase the effective length of the cutting edge in the axial direction, and when the effective length of the cutting edge is increased in the conventional technology published in the above publication, the size of the chip pocket makes it difficult to eject chips. There is a problem that efficient processing cannot be carried out due to the decrease in properties.

The present invention was developed to solve these problems, and it is possible to set the effective cutting edge length in the direction of the central axis of the main body to be large, and also to improve chip evacuation and achieve efficient machining. The object of the present invention is to provide a throw-away ball end mill that can perform

(Means for Solving the Problems) The throw-away ball end mill of the present invention has a rod-shaped tool body with approximately
First and second flute grooves are formed 180° apart, a first peripheral blade tip is attached to the first flute groove, a second peripheral blade tip is attached to the second flute groove, and A plate-shaped central blade chip consisting of three arcuate sides and a roughly triangular upper and lower surface with a central mounting hole is attached to the tip of the tool body so as to be eccentric from the rotation center of the tool body, and the chip to which this central blade chip is attached is The feature is that a chip pocket is provided adjacent to the seat.

That is, the tool body is provided with first and second flute grooves, each consisting of a horizontal surface and an upright surface, extending in the direction of the central axis of the tool body and spaced apart from each other by about 180 degrees in the circumferential direction of the tool body. 1st
A chip seat is formed on the horizontal surface of the flute groove to receive the first peripheral cutting chip, and a chip seat is formed on the horizontal surface of the second flute groove to receive the second peripheral cutting chip, respectively. , a chip seat for receiving the center blade chip and a chip pocket adjacent to the chip seat are formed in a portion extending from the center of rotation of the most extreme surface to the chip seat formed in the first flute groove, and a chip pocket adjacent to the chip seat is formed to receive the center blade chip. The tool body is formed into a plate shape consisting of three arcuate side surfaces and a substantially triangular upper and lower surface having a central mounting hole, and is screwed into a chip seat formed on the most extreme surface of the tool body using the central mounting hole. The tip is stopped so that the starting point of the cutting edge of the central cutting tip is located near the center of rotation of the tool body, and the arcuate side surface forms a rake face for cutting, and the substantially triangular upper and lower surfaces form a flank surface. The first peripheral cutting edge tip has a peripheral cutting edge consisting of an arcuate edge and a straight edge, and the cutting edge starting point of the arcuate edge is on the rotation locus and the circular cutting edge edge of the center cutting edge is The second peripheral cutting edge tip has an outer peripheral cutting edge ridge consisting of an arcuate edge and a straight edge, and the cutting edge starting point of the arcuate edge is on the rotation trajectory,
It is characterized in that it is set so as to overlap halfway with the arcuate cutting edge ridge of the center blade tip.

In addition, a supply passage for a cutting blade tip cooling medium extending in the direction of the center axis of the main body is provided in the tool body and a shank portion following this body, and an injection port at the end of this supply passage is provided in the center blade tip. for the chip pocket, for the first peripheral blade chip, for the raised surface of the first flute groove, for the second peripheral blade chip, for the second peripheral blade chip.
It is preferable to provide the flute grooves so that they are branched and opened on the upright surfaces of the flute grooves.

Furthermore, it is effective to form the center edge tip from a cemented carbide, and to form the cutting edge portions of the first and second peripheral edge tips from an ultra-high pressure sintered body.

(Function) According to the above configuration, approximately 180° from each other in the circumferential direction of the main body.
Two flute grooves extending in the direction of the center axis of the main body are provided in a spaced relationship, and a peripheral cutting tip is provided in each flute groove, and a plate-shaped plate consisting of three arcuate side surfaces and a substantially triangular upper and lower surface is provided at the tip of the main body. The center blade tip is arranged eccentrically from the center of rotation of the main body so that this arcuate side surface becomes the rake surface, and a chip pocket is formed adjacent to the chip seat for attaching this center blade tip. In addition to making it possible to stably attach a long peripheral edge tip in the direction of the center axis, the shape and arrangement of the center edge tip, peripheral edge tip, flute groove, and chip pocket have been devised so that chips can be efficiently discharged. Therefore, the effective length of the cutting edge in the direction of the central axis of the main body can be set to be large, and efficient machining can be performed by obtaining good chip evacuation properties.

Furthermore, by providing the supply passage for the cutting edge cooling medium as described above, each cutting edge tip can be cooled individually, and it is possible to improve the cutting speed and machining efficiency.

Furthermore, as mentioned above, by forming the center edge tip with cemented carbide and the cutting edge part of the outer edge tip with ultra-high pressure sintered material, it becomes possible to perform high-speed cutting. Even if a large thrust load is applied to the edge or the edge is strongly rubbed by the material to be cut, it is possible to prevent the side edge from being damaged.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1 and 2 are a side view and a front view showing a throw-away ball end mill according to a first embodiment of the present invention. This ball end mill is
A first flute groove 9 and a second flute groove 10 are formed in a circumferential direction of the side wall of a tool body 1, which has a hemispherical tip and is formed into a cylindrical shape with a diameter of about 50 mm, for example, and is spaced approximately 180 degrees from each other. , this first flute groove 9 has a first peripheral cutting tip 3, and a second flute groove 9.
A second peripheral cutting tip 4 is attached to the flute groove 10, and a substantially triangular plate-shaped center cutting tip 2 is attached to the tip of the tool body 1 eccentrically from the rotation center of the tool body 1. be.
Further, the first and second flute grooves 9, 10
extends in the direction of the central axis of the main body 1 and consists of horizontal surfaces 5, 7 and upright surfaces 6, 8, which are perpendicular to each other, and each horizontal surface 5, 7 has a peripheral blade tip 3, 4.
Chip seats 11 and 12 are formed to receive the chips. Further, the center cutting tip 2 is attached to a tip seat 13 formed in a portion extending from the center of rotation of the most extreme surface of the tool body to a tip seat 11 formed in the first flute groove 9.
A chip pocket 14 is formed in a portion adjacent to. The center blade tip 2 described above is formed into a plate shape consisting of three arcuate side surfaces 2a and approximately triangular upper and lower surfaces 2c, and a center mounting hole 2b is formed in the center of the upper and lower surfaces 2c. The chip 2 is screwed to the chip seat 13 by a screw 2e passing through the central mounting hole 2b. At this time, the starting point of the cutting edge of the central cutting tip 2 is located near the center of rotation of the tool body 1, the arcuate side surface 2a constitutes a rake surface for cutting, and the substantially triangular upper and lower surfaces 2c constitute a flank surface. In addition, the first and second peripheral blade tips 3,
4 are circular edges 3a, 4a and straight edges 3b, 4, respectively.
The straight edge 3b, 4b makes it possible to increase the effective length of the cutting edge in the direction of the central axis of the main body. Further, as mentioned above, since the center blade tip 2 is offset from the rotation center of the main body 1 in the direction of the first flute groove 9, the first peripheral blade tip 3
The starting point of the cutting edge of the circular arc ridge 3a substantially overlaps with the cutting edge end point of the circular cutting edge 2d of the center blade tip 2, whereas the cutting edge starting point of the circular arc ridge 3a of
The cutting edge starting point of the arcuate edge 4a of the outer peripheral edge tip 4 overlaps the arcuate cutting edge 2d of the center edge tip in the middle.

Further, in the center of the tool body 1 and the shank portion 1a following the body 1, a supply passage 21 for supplying a cutting tip cooling medium, generally called an oil hole, is provided in the direction of the central axis of the body 1. This supply passage 21 is formed to have a diameter of about 6 mm. The end of the supply passage 21 toward the tip of the main body is branched into three parts, and the cooling medium is supplied to the chip pocket 14, the upright surface 6 of the first flute groove 9, and the upright surface 8 of the second flute groove 10. an injection port 22a for ejecting
22b, 22c are formed so that each cutting edge tip 2, 3, 4 can be individually cooled.

When performing cutting using the above-mentioned throw-away ball end mill, attach the shank 1a to the milling machine, and while rotating this ball end mill in the direction of arrow B at, for example, 3200 rpm,
For example, 2000mm/with the tip in contact with the workpiece.
Performs lateral feed at a speed of min. At this time, the center blade tip 2 rotates around the center axis of the main body, and 1
The workpiece is cut using the two arcuate side surfaces 2a as cutting surfaces (rake surfaces). If one arcuate side surface 2a is worn, the center blade tip 2 is rotated 120 degrees and reset so that another arcuate side surface 2a becomes the starting point of the cutting edge. Chips of the workpiece cut by the central blade tip 2 are discharged from a chip pocket 14 formed into a predetermined curved shape as shown in the figure. The chip pocket 14 is compactly located at a portion sandwiched between two flute grooves 9 and 10 at the tip of the main body.
It is also formed in a concave curved shape to improve chip evacuation. As mentioned above, this central cutting chip 2 has the arcuate side surface 2a as the rake surface, the arcuate triangular upper surface 2c as the relief surface, and the thickness of the chip is increased in the direction in which it receives the force from the workpiece during cutting. Because of this, it can withstand even large cutting forces.

On the other hand, the two peripheral blade tips 3 and 4 are attached to the tip seats 1 provided on the horizontal surfaces 5 and 7 of the flute grooves 9 and 10 by bolts 3e and 4e, respectively, as shown in the figure.
1 and 12, and is further held by clamps 3f and 4f so as not to shift from this position. The first peripheral cutting tip 3 is formed to have a blade length of 35 mm, a blade width of 15 mm, and a blade thickness of 4.76 mm, for example.
Further, the second peripheral blade tip 4 has a blade length of 40 mm, for example.
The blade width is 15mm and the blade thickness is 4.76mm. Further, the flute grooves 9 and 10 for receiving these peripheral cutting chips 3 and 4 are longer than the blade length of the peripheral cutting chips 3 and 4, and are provided to a position located about 57 mm toward the rear end from the tip of the tool body 1, for example. Moreover, since the two flute grooves 9 and 10 are formed at positions 180° apart from each other in the circumferential direction of the main body 1, the outer circumferential cutting tip 3,
The evacuation of chips cut by No. 4 is extremely good. Although there is a concern that the rigidity of the tool body 1 will decrease as a result of making the flute grooves 9 and 10 larger in this way, the shape and placement position of the center cutting edge tip 2 have been devised to make the chip pocket 14 more compact. This prevents the above-mentioned significant decrease in rigidity.

3 and 4 are a side view and a front view showing a throw-away ball end mill of a second embodiment different from the embodiment shown in FIGS. 1 and 2. FIG. In addition, in FIGS. 3 and 4, parts with the same symbols as in FIGS. 1 and 2 are as follows.
Since it has the same function as the portion shown in FIG. 1 and FIG. 2, the description thereof will be omitted. Second
The ball end mill of the embodiment is different from the ball end mill of the first embodiment described above in that the peripheral blade tip 3,
The configuration of 4 is different.

That is, both the peripheral blade tips 3 and 4 have cutting edge portions 3d and 4d made of a CBN (cubic boron nitride) sintered body on the substrates 3c and 4c made of cemented carbide, thereby enhancing wear resistance. ing. On the other hand, the center blade tip 2 is made of cemented carbide. As a result, the peripheral cutting edge chips 3 and 4 located on the outer periphery of the tool body 1, which have a high cutting speed, are made to have excellent wear resistance, and the central cutting edge tip 2, which is located closest to the center axis of the tool body, is made to have relatively toughness. Since it can be made high, it can handle high-speed cutting, and even if a large thrust load is applied to the edge of the cutting edge of the center cutting edge 2 or this edge is strongly rubbed against the workpiece material, this part can be easily cut. It is possible to prevent loss of.

The material of the cutting edge portions 3d and 4d of the peripheral edge chips 3 and 4 described above is not limited to CBN sintered body, but may be other materials such as WBN sintered body (Wurtz type boron nitride) or diamond sintered body. It is also possible to use an ultra-high hardness sintered body.

Note that the shapes and sizes of the tool body 1, the center edge tip 2, the two peripheral edge tips 3, 4, the chip pocket 14, the flute grooves 9, 10, etc. are not limited to those of the above-mentioned embodiments, and may be modified in various ways. It is possible to change the shape and size.

(Effects of the invention) As explained above, according to the throw-away ball end mill of the invention, two flute grooves are provided, and a peripheral cutting tip that is long in the direction of the center axis of the main body can be stably mounted in the grooves. At the same time, the shape and arrangement of the center cutting edge tip and chip pocket are designed to be compact and to improve chip evacuation, so the effective cutting edge in the direction of the center axis is reduced compared to conventional ones. It is possible to set a large length and to obtain good chip evacuation properties, making it possible to perform efficient cutting.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a throw-away ball end mill according to the first embodiment of the present invention, Fig. 2 is a front view of the throw-away ball end mill shown in Fig. 1 as viewed from the direction of arrow A, and Fig. 3 is a side view showing the throw-away ball end mill of the first embodiment of the present invention. FIG. 4 is a side view showing a throw-away ball end mill according to a second embodiment of the present invention, and FIG. 4 is a front view of the throw-away ball end mill shown in FIG. 3 when viewed from the direction of arrow C. 1... Tool body, 2... Center blade tip, 3...
First peripheral blade tip, 4... Second peripheral blade chip, 5, 7... Horizontal surface, 6, 8... Upright surface, 9...
...First flute groove, 10...Second flute groove, 1
1, 12, 13... Chip seat, 14... Chip pocket, 21... Cutting blade chip cooling medium supply passage,
22a, 22b, 22c... injection ports.

Claims (1)

[Scope of claims for utility model registration] (1) A rod-shaped tool body 1, a center cutting tip 2,
In the indexable ball end mill in which a first peripheral cutting edge tip 3 and a second peripheral cutting edge tip 4 are respectively attached, the tool main body 1 has a central axis extending from the tip to the rear end of the main body 1. , a first flute groove 9 consisting of a horizontal surface 5 and an upright surface 6, and a horizontal surface 7.
and a second flute groove 10 consisting of an upright surface 8 are provided in the circumferential direction of the main body 1 in a positional relationship that is approximately 180° apart from each other, and the first peripheral cutting tip is provided on the horizontal surface 5 of the first flute groove 9. , said second
The horizontal surface 7 of the flute groove 10 is formed with chip seats 11 and 12 for receiving the second peripheral cutting chip, respectively. A chip seat 13 in which the center blade tip 2 is received and a chip pocket 14 adjacent to the chip seat 13 are formed in the portion leading to the chip seat 11 formed in the 1-flute groove 9. Arc side 2
a, and a generally triangular upper and lower surface 2c having a central mounting hole 2b.
3 using the center mounting hole 2b, and the cutting edge starting point of the center blade tip 2 is located near the rotation center of the tool body 1, and the arcuate side surface 2a is the rake surface for cutting. The substantially triangular upper and lower surfaces 2c constitute flank surfaces, and the first peripheral cutting edge 3 has a peripheral cutting edge consisting of a circular arc edge 3a and a straight edge 3b, and the circular arc The starting point of the cutting edge of the ridge 3a is set to substantially overlap the cutting edge end point of the arcuate cutting edge 2d of the central blade tip 2 on the rotation locus, and the second peripheral edge tip 4 has the arcuate edge 4a and the straight edge. 4b, and the cutting edge starting point of the arcuate edge 4a is set to overlap halfway with the arcuate cutting edge ridge 2d of the central blade tip 2 on the rotation locus. Throwaway ball end mill. (2) The tool body 1 and the shank portion 1a following this body are provided with a supply passage 21 for a cutting chip cooling medium in the direction of the central axis of the body 1, and an injection passage 21 at the end of this supply passage 21 is provided. Openings 22a, 22b, 22c are provided in the chip pocket 14 for the center blade tip 2, in the upright surface 6 of the first flute groove 9 for the first peripheral blade tip 3, and in the second 2. The throw-away ball end mill according to claim 1, wherein the peripheral blade tips 4 are provided on the upright surface 8 of the second flute groove 10 so as to branch and open, respectively. (3) a cutting edge portion 3d in which the center blade tip 2 is made of a cemented carbide, and the first peripheral blade tip 3 and the second peripheral blade tip 4 are made of an ultra-high pressure sintered body;
3. The throw-away ball end mill according to claim 1, further comprising: 4d.