JPH0115457Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a throw-away type end mill, and is particularly suitable for small-diameter end mills, such as those with a cutting edge diameter of 50 mm or less.

(Prior Art) Conventionally, this type of indexable end mill has been disclosed, for example, in Japanese Utility Model Publication No. 58-48014. In the device disclosed in this publication, two throw-away tips made of triangular plates are fixed by a lid member, a tightening screw, or the like.

(Problem to be solved by the invention) However, the throw-away type end mill seen in the above-mentioned publication lacks strength if the rake angle in the axial direction is set to a large square angle due to the structure of the lid member. It was not suitable for cutting materials, and there were problems in that the cutting performance was insufficient.

Therefore, the present invention attempts to solve the above-mentioned problems by improving the angular configuration, mounting rigidity, and chip evacuation of the throw-away tip so as to improve cutting performance.

(Means for Solving the Problems) The present invention was devised in view of the above-mentioned points.At least one flute groove is notched in the axial direction at one end of the cylindrical tool body, and the flute groove is cut out in the axial direction. To provide an improved indexable end mill in which a triangular plate-shaped indexable tip is fixed in a tip seat provided on a flute surface of a groove by a presser foot and a tightening screw. .

That is, regarding the angular configuration of the throw-away tip, the rake angle α in the axial direction is set within the range of 7° to 18°, and the rake angle β in the radial direction is set within the range of −10° to 0°.

Further, the presser foot has a mounting hole formed approximately in the center thereof, the bottom surface of which has a concave shape so as to form a pressing convex surface, and the upper surface thereof has two holes with a step. Two chip pocket surfaces are arranged diagonally.

Furthermore, the tightening screw is positioned within the mounting hole of the presser foot so that its head does not protrude significantly from the presser foot.

(Function) The throw-away type end mill of the present invention achieves good cutting by setting the axial rake angle α within the range of 7° to 18° and the radial rake angle β within the range of -10° to 0°. It is something that works.

In addition, the throw-away end mill of the present invention has a mounting mechanism using a presser foot and tightening screws, which increases the mounting rigidity of the throw-away tip, and the structure of the presser foot with two stepped chip pocket surfaces improves chip disposal. It also works well.

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

In FIGS. 1 to 3, reference numeral 1 denotes a cylindrical tool body, with a flute groove 2 cut out in the outer circumferential portion of its tip, and a shank 3 in the rear end.
are installed in succession.

The flute groove 2 has a chip seat 5 formed on the flute surface 13 for receiving a triangular plate-shaped throwaway chip 4.
is fixed by a presser foot 6 and a tightening screw 7.

The throw-away tip 4 has a side edge that forms an outer peripheral cutting edge ridge 8 that is substantially parallel to the shaft center line, and also forms a rake angle α in the axial direction and a rake angle β in the radial direction. In this case, the axial rake angle α is between 7° and 18°, and the radial rake angle β
is set within the range of −10° to 0°. This is based on the cutting results shown in FIGS. 7 to 9, which will be described later.

Note that although the outer diameter D of the cutting edge is 20 mm in the illustration, it is set to α=7° and β=−9°.

The presser foot 6 has a mounting hole 9 for a tightening screw 7 formed approximately in the center thereof, and chip pocket surfaces 10 and 11 with two steps are obliquely provided on one side edge of the upper surface thereof. ing.

The recessed chip pocket surface 10 on the side of the throw-away tip 4 serves to curl chips that have rubbed against the rake surface of the throw-away tip 4, and the chip pocket 11 on the side of the flute surface 13 serves to curl the chips that have rubbed against the rake surface of the throw-away tip 4. If there are chips that curl and extend, they collide and break. Especially when the axial rake angle α is 7°~
Since the angle is set at 18 degrees, the chips extend in the axial direction, so it is important to break the chips to an appropriate length.
Furthermore, the bottom surface of the presser foot 6 is concave,
Along with this, pressing convex surfaces 12a formed at both ends,
12b are brought into contact with the throwaway tip 4 and the flute surface 13, respectively.

Further, the tightening screw 7 is inserted through the mounting hole 9 of the presser foot 6 and screwed into the threaded hole 14 of the flute surface 13 located rearward of the tip seat 5 in the axial direction. The head of the tightening screw 7 is designed not to protrude significantly from the presser foot 6 so as not to obstruct the discharge of chips. Further, as a result, the tightening center of gravity is lowered and the rotation stopper 6a of the presser foot 6 is present, so that the pressing force of the throw-away tip 4 is increased and the mounting rigidity is increased.

Furthermore, in FIGS. 4 to 6, as modified examples,
A two-blade version is shown. In the illustrated case, the outer diameter D of the cutting edge is 50 mm, the axial rake angle α of the throw-away tip 4 is set to 15°, and the radial rake angle β is set to −3°.

Note that the throwaway chip 4 is made of TiN, TiC.
By forming a hard coating layer such as, the cutting performance is enhanced.

Note that the rake angle α in the axial direction mentioned above is 7° to 18°,
The rake angle β in the radial direction was set to −10° to 0° based on the cutting test results shown in FIGS. 7 to 9.

In FIG. 7, the horizontal axis represents the axial rake angle α, and the vertical axis represents the cutting distance in the feeding direction until the end of the tool life. In this case, the work material is SUS304, and the tool specifications are that the cutting edge diameter D is φ30 mm and the radial rake angle β is 0°. In addition, the cutting conditions are: cutting speed V = 100 m/min, feed S _Z = 0.1
mm/tooth, depth of cut a = 5.0 mm, cutting width = 15 mm.

On the other hand, in FIGS. 8a and 8b, the maximum values in the X and Y directions were measured using the rake angle α in the axial direction as a parameter. In this case, the horizontal axis is
The feed was adjusted and S55C (H _B 215) was selected as the work material. The cutting conditions are cutting speed V=100m/
min, depth of cut a = 2 mm, cutting width = 20 mm, and right angle shoulder milling was performed with a single-flute down cut. And for the axial rake angle α=20°,
As seen in Figure 8 a and b, the maximum value in the X direction, the Y
Although the maximum value in the direction was small, the tool rigidity was weakened, so the cutting distance was short as seen in FIG. As a result, the optimum range for the rake angle α in the axial direction was 7° to 18°.

FIG. 9 shows an investigation of the influence of tool chatter due to changes in the radial rake angle β, with cutting width plotted on the horizontal axis and depth of cut on the vertical axis. In this case, the work material is S55C (H _B 230) and the tool specifications are:
The cutting edge diameter D = φ20 mm, the axial rake angle α = 7°, the corner angle CA = 0°, and the number of teeth was 1. The cutting conditions were as follows: cutting speed V = 120 m/min, feed rate S _Z = 0.1 mm/tooth, and right-angled shoulder milling was performed by down-cutting. As a result, the range of −10° to 0° was suitable for the rake angle β in the radial direction. In this case, rake angles in the radial direction exceeding -10° were excluded because the negative angles were too strong and caused problems such as chipping of the cut surface.

Furthermore, FIG. 10 compares the load fluctuations applied to the milling machine table from when the cutting blade bites into the workpiece to when it separates from the product of the present invention and the comparative product. In this case, the comparative product has an axial rake angle as shown in Figure 10.
5°, and the radial rake angle is set to 0°.

As a result, the product of the present invention has X,
It was confirmed that there was little variation in both the Y and Z directions.

(Effects of the invention) The indexable end mill of the invention constructed in this way has the following effects.

First, the sharpness is good and the cutting performance is improved. This is because, as is clear from FIG. 10, there is little variation in the load applied to the milling table and stable cutting can be achieved.

Second, it has high mounting rigidity. this is,
This is because the above-mentioned cutting test shown in FIG. 10 corresponds to a so-called durability test, and no slip-out of the throw-away tip 4 or loosening of the presser foot 6 was observed in this test.

Thirdly, it can be applied to small-diameter objects. This is the cutting depth d=6 in steel cutting.
This is because it was possible to cut grooves of mm or more and right angle shoulders with a depth of cut of 8 mm or more. Therefore, various types of medium to rough machining such as grooving and right angle shoulder milling are applied as work applications.

[Brief explanation of the drawing]

Figure 1 is a front view of the indexable end mill of the present invention, Figure 2 is its bottom view, and Figure 3 is a front view of the indexable end mill of the present invention.
The figure is a partial side view, Figure 4 is a front view showing a modified example, Figure 5 is a bottom view thereof, Figure 6 is a partial side view thereof, and Figure 7 is an axial direction on the horizontal axis. Explanatory diagrams showing the effective range of rake angle, Figure 8 a and b are for X direction, Y direction
Figure 9 is an explanatory diagram showing the maximum values in each direction.
FIG. 10 is an explanatory diagram showing the range of chatter in the radial rake angle, and FIG. 10 is an explanatory diagram showing a comparison of load fluctuations in the product of the present invention and the comparative product. 1... Tool body, 2... Flute groove, 4... Throwaway tip, 5... Chip seat, 6... Presser foot, 7... Tightening screw, 8... Peripheral cutting edge ridge, 1
0, 11...Chip pocket surface, 12...Press convex surface, 13...Flute surface.

Claims (1)

[Claims for Utility Model Registration] At least one flute groove 2 is notched in the axial direction at one end of the cylindrical tool body 1, and the tip seat 5 provided on the flute surface 13 of the flute groove 2 is cut out. In this case, a triangular plate-shaped throw-away tip 4 is fixed by a presser foot 6 and a tightening screw 7, and an outer cutting edge 8 formed on the throw-away tip 4 is approximately parallel to the axial direction of the tool body 1. In the indexable end mill, which is located so that The presser foot 6 has a mounting hole 9 approximately in the center.
is bored, and a pressing convex surface 12 is provided on the bottom surface of the hole.
a, 12b are formed, and one pressing convex surface 12a is in contact with the throwaway tip 4, and the other pressing convex surface 12b is in contact with the throwaway tip 4.
is in contact with the flute surface 13 located rearward in the axial direction,
Furthermore, on the top surface, two steps are formed at one end of the top surface.
Two chip pocket surfaces 10 and 11 are arranged diagonally, one chip pocket surface 10 is recessed, and the other chip pocket surface 11 is located on the throwaway tip 4 side, and the other chip pocket surface 11 is located on the axially rearward side of the flute. The tightening screw 7 is fitted into the mounting hole 9 of the presser foot 6, and its threaded portion is screwed into the screw hole 14 provided in the flute surface 13 of the tool body 1. , a throw-away type end mill characterized in that its head does not protrude significantly from the mounting hole 9 of the presser foot 6.