JP2001071210A - Christmas tree formed milling cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the good cutting quality of each cutting edge part and to improve the chip discharging performance and the rigidity of a tool by forming a cutting edge of each conical stage by a right twisted blade and a left twisted blade, and alternately arranging right twisted blades and left twisted blades in zigzag while longitudinally deviated from each other in the circumferential direction. SOLUTION: Right twisted blades 17 are located at a front side of each conical part 16, left twisted blades 18 are located at a rear side of each conical part, and the right twisted blades 17 and the left twisted blades alternately arranged in the circumferential direction in zigzag. The chip produced by the right twisted blades 17 is taken in a right twisted groove part 19a and flows in the blade root direction of the cutter, on the other hand, the chip produced by the left twisted blades 18 is taken in a left twisted groove part 19b and flows in the point direction of the cutter. Whereby the chips flowing at the directions opposite to each other are interfered with each other at a joining part of the groove parts 19a, 19b. The axial flowing-out force of the chip is canceled by the mutual interference, and the chip is discharged to the rear part in the feeding direction of the cutter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Christmas cutter used for forming a groove in a turbine blade or a turbine disk, and a blade groove cutter for processing a single-stage blade groove.

[0002]

2. Description of the Related Art FIG. 14 shows an example of a groove to be processed. To process the groove S in one pass, a Christmas cutter as shown in FIG. 13 is used. This Christmas cutter 1
The main body 2 has a shape in which a conical portion 3 and a constricted portion 4 are alternately connected, and a cutting blade 5 is attached to a region of a length L of the main body 2. The cutting blades 5 include a straight blade shown in the figure and a right-handed or left-handed cutting blade having excellent cutting performance, and usually about three or four cutting blades 5 are provided. The processing by the Christmas cutter is performed by a method in which the cutter is traversed and cut into the work. By the traverse, the contour of the main body 2 is transferred, and the groove S as shown in FIG. It is formed.

[0003]

With a right-handed right-handed tool or a right-handed left-handed tool, chips are discharged in the direction of the root or tip of the tool. However, in the processing by the Christmas cutter, there is no place for the chips to escape in the tip direction. In addition, in order to improve the processing efficiency, a ring cutter has recently been installed at the base of the Christmas cutter, and it has been attempted to machine the work end face at the entrance of the machining groove with the ring cutter simultaneously with the groove processing. In addition, the flow of chips in the root direction is easily blocked by the ring cutter, and therefore, it is difficult to achieve smooth and high-speed processing with the conventional Christmas cutter, especially when the ring cutter is used in combination.

As shown in FIG. 15, a right-edge right-handed cutter has a negative blade angle β on the rear side of the conical portion 3 (the front side in the case of right-edge left-handed twisting). The phenomenon deteriorates the surface roughness of the machined surface, increases the cutting resistance, easily causes chatter (vibration), and deteriorates machining stability.

[0005] Therefore, an object of the present invention is to realize and provide a high-performance Christmas cutter that eliminates the above-mentioned problems.

[0006]

In order to solve the above-mentioned problems, in the present invention, the cutting blade of the conical part of each stage of the Christmas cutter is constituted by a right twist blade and a left twist blade. For the right blade cutter, the right twist blade is on the front side of the conical part, the left twist blade is on the rear side, and for the left blade cutter, the left twist blade is on the front side of the conical part and the right twist blade is on the rear side. Thus, they were alternately arranged in a zigzag pattern in the circumferential direction.

This cutter extends a cutting edge on the rear side of the conical portion to form a conical cutting edge connecting the conical portions with the extending portion. It is preferable to connect the cutting blades on the front side of the section.

It is also preferable that the end of the cutting edge on the front side of each conical portion is located behind the starting end of the cutting edge on the rear side.

In addition, in terms of cutting performance, the greater the number of blades, the better. However, as the number of blades increases, the amount of back metal of each blade decreases, and tool rigidity decreases. Therefore, the root part diameter D shown in FIG. 2 is about 50 mm, the effective part length L _{1 is} about 60 mm,
When a cutter with a taper angle θ = 32 ° was examined,
The cutting edge on the front side of the conical part, the cutting edge on the rear side and the cutting edge on the constricted part are each three, the rake angle of each cutting edge is about 6 °, and the torsion angle of the front cutting edge of the conical part of each step is A blade with a helix angle of about 25 ° and a helix angle of the rear cutting edge of 20 ° to 35 ° was excellent in sharpness, chip dischargeability and tool rigidity were satisfactory and particularly preferred.

[0010] In addition to the Christmas cutter for processing a multi-stage blade groove, there is also a blade groove cutter for processing a single-stage blade groove, and the present invention is applied to the cutter for the single-stage blade groove. Is also effective.

With respect to the cutter for the single-stage blade groove, the cutting blade provided in the conical portion bulging outward in the radial direction at the tip of the main body is constituted by a right twist blade and a left twist blade. For the right blade cutter, the right twist blade is on the front side of the conical part, the left twist blade is on the rear side, and for the left blade cutter, the left twist blade is on the front side of the conical part, and the right twist blade is on the rear side. The configuration is such that the cutting edges on the rear side of the conical portion are connected to the cutting edges of the straight portion continuously provided behind the conical portion in a staggered arrangement in the circumferential direction.

[0012]

[Effect] One of the chips generated by the right twisting blade and the chips generated by the left twisting blade is directed toward the root of the cutter.
The other tries to flow in the tip direction. And they both interfere with each other. Therefore, the flow output in the axial direction is weakened, the chips are discharged without delay behind the cutter in the feed direction, and the processing proceeds smoothly.

[0013] Further, by combining the right twist blade and the left twist blade, the blade angle of each of the cutting blades becomes positive on both the front side and the rear side of the conical portion, so that the sharpness is improved and the machined surface becomes clean.

Further, the cutting force is reduced by improving the sharpness, and the thrust loads acting on the right-handed and left-handed blades cancel each other, so that the vibration of the cutter is suppressed.

[0015]

1 to 9 show an embodiment of a Christmas cutter according to the present invention. The Christmas cutter 10 is a right-edge cutter having a web taper, and is formed by connecting a screw portion 12 and a main body portion 13 to a tip end of a tool shank 11. A ring cutter (not shown) for processing the end face of the workpiece at the entrance of the processing groove is attached to the screw portion 12 as necessary.

The main body 13 is formed by alternately connecting a constricted portion 15 in front of a tapered base portion 14 and three conical portions 16 whose size is increased toward the base.

As shown in FIGS. 4 to 6, each of the conical portions 16 is provided with three right-hand twisting blades 17 and three left-hand twisting blades 18 at a constant pitch in the circumferential direction. The right twist blade 17 is located on the front side of each conical portion 16 and the left twist blade 18 is located behind the conical portion. The right twist blades 17 and the left twist blades 18 are alternately arranged in the circumferential direction in a staggered manner.

The left twist blade 18 extends to the constricted portion 15, and the extended portion forms a constricted cutting edge.

The right twist blade 17 and the left twist blade 1 of each conical portion 16
8, as shown in FIG. 9, the right twisting blade 17 is arranged such that the terminal end thereof is Δn (approximately 1.5 to 2.5 mm) behind the starting end of the left twisting blade 18. Although the overlapping arrangement of the cutting blades is a well-known technique, it is adopted because it is effective for improving the connection state of the work surface by each blade.

In order to achieve both high rigidity and good chip discharge performance, the cutter shown in FIG.
At the end of the left twist blade 18, a right twist blade 17 of the next conical portion is connected (the right twist blade 17 provided at the root tapered portion 14 is also connected to the upper left twist blade 18). , The twist angle λ of the right twist blade 17 is all unified to 25 °, and the left twist blade 18
The torsion angle of the cutting edge of the cutting edge cone is λ ₁
20 °, the torsion angle λ ₂ of the blade of the second conical part is 35 °,
The twist angle λ ₃ of the blade at the third conical portion was set to 30 °. In addition, the cutting blade of each part was provided with a rake angle γ of 6 ° (see FIGS. 7 and 8) to improve the sharpness.

Thus, a chip discharge groove 19 is formed in which the right twist groove 19a along the right twist blade 17 and the left twist groove 19b along the left twist blade 18 are joined.
A sufficient amount of back metal can be secured in the vicinity of the junction of 9b (the portion that becomes a delta).

The chips generated by the right twist blade 17 are taken into the right twist groove 19a and directed toward the root of the cutter, while the chips generated by the left twist blade 18 are collected into the left twist groove 19b. The cutter tries to flow toward the tip of the cutter. For this reason, mutual interference of the chips which are going to flow in the opposite direction at the junction of the grooves 19a and 19b occurs. Further, a part of the chips flowing into the groove 19b flows from the start end of the groove 19b into the groove 19a on the rear side in the cutter rotation direction through the flank on the outer periphery of the conical portion, and here, the cutting direction is reversed. Powder interference occurs. Due to the mutual interference, the chips lose the flow output in the axial direction and are discharged backward in the feed direction of the cutter.

The torsion angles of the torsion blades 17 and 18 are not limited to the above-mentioned values. However, for a cutter having three right and left torsion blades, values far apart from each other are selected. Since the balance between the assignment of the cutting blade and the twist groove may be deteriorated and either the tool rigidity or the chip discharge performance may be sacrificed, the above value or a value close to it is preferable.

FIGS. 10 and 11 show an embodiment of a blade groove cutter for processing a single-stage blade groove.

The blade groove cutter 20 has a body 22 connected to the tip of a shank 21.

The main body 22 has a structure in which a conical portion 24 bulging radially outward is provided in front of the straight portion 23, and a right twist blade 25 and a left twist blade 26 are provided on the outer periphery of the conical portion 24 in the circumferential direction. Three pieces are provided at a constant pitch, and further, chip discharge grooves 27 and 28 are provided along each twisted blade.

The right twist blade 25 is located on the front side of the conical portion 24 and the left twist blade 26 is located on the rear side.
6 are alternately arranged in a zigzag pattern in the circumferential direction.

The left twist blade 26 extends to the rear end of the straight portion 23, and the extension portion extends the straight portion 23.
Is formed.

The starting end of the right twist blade 25 forms a bottom blade with a water mark. Further, the chip discharge groove 27 along the right twist blade 25 is connected to a left twist chip discharge groove 28 which has dropped further deeper through a stepped left twist groove 29.

In the illustrated cutter, the right torsion blade 25 and the left torsion blade 26 both have a torsion angle of 20 °, the outer rake angle is 6 °, the bottom blade has a rake angle of 2 °, and the bottom blade has a top angle of 2 °. 6 clearance angle
°, second relief angle 25 °, right twist blade 25, left twist blade 26
The first outer clearance angle is set to 8 °, the second outer clearance angle is set to 30 °, and the right angle groove angle (δ in FIG. 11) is set to 55 °, but this is only a preferable specification.

Also in the blade groove cutters of FIGS. 10 and 11 configured as described above, mutual interference of the chips discharged from the right and left-handed chip discharge grooves occurs, and therefore, the axial flow output of the chips is reduced. The chips are lost and the chips are smoothly discharged backward in the feed direction of the cutter.

Further, the blade angle does not become negative on the rear side of the conical portion 24, and the wrinkle phenomenon by the blade is prevented, and the chatter due to a decrease in the surface roughness of the processed surface and an increase in the cutting resistance is also eliminated.

FIG. 12 shows a right twist blade 25 provided by the same number.
And a notch 30 at a predetermined pitch on the left-handed twist blade 26 to roughen the cutter. Notch 3 for each blade
If the phase is shifted by 0 so that the complementary cutting is performed at the portion having the notch and at the portion not having the notch, the cutting force can be reduced, and the rough cutting can be performed with a large allowance. In addition, the notch 30 can be sharpened to improve the sharpness by sharpening the blade at the portion where the notch 30 is cut out, but may be a general nick or the like.

[0034]

As described above, in the Christmas cutter of the present invention, the cutting edge of the conical portion of each stage is constituted by the right twisting blade and the left twisting blade, and the right twisting blade and the left twisting blade are arranged back and forth. By shifting the position and alternately arranging in the circumferential direction in a staggered manner, good sharpness of each part of the cutting blade is maintained, and at the same time, chip discharge performance and tool rigidity are improved, and a good vibration suppression effect is obtained. In addition, a groove having good surface roughness can be stably processed, and a high-speed processing can be realized.

It should be noted that the cutter according to the embodiment has particularly large effects of improving rigidity and chip dischargeability, and provides better results.

In the blade groove cutter for processing a single-stage blade groove, the cutting edge of the conical portion at the tip is composed of a staggered right twisted blade and left twisted blade. The chip discharge performance can be improved, and cutting performance and processing accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a Christmas cutter according to the present invention.

FIG. 2 is a longitudinal sectional view showing the cutter in an expanded state.

FIG. 3 is a front view of the cutter.

FIG. 4 is a front view of a conical portion at the tip.

FIG. 5 is a front view of a second-stage conical portion.

FIG. 6 is a front view of a third-stage conical portion;

FIG. 7 is an enlarged sectional view of an XX line portion (or a YY line portion) of FIG. 1;

FIG. 8 is a sectional view taken along the line ZZ in FIG. 1;

FIG. 9 is an exploded view showing the arrangement of the cutting blade in each part.

FIG. 10 is a partially broken side view showing another embodiment of the blade groove cutter.

FIG. 11 is a front view of the same cutter.

FIG. 12 is a diagram showing a state in which a notch is provided in a cutting blade.

FIG. 13 is a side view of a conventional Christmas cutter.

FIG. 14 is a diagram showing an example of a groove shape processed by a Christmas cutter.

FIG. 15 is a diagram showing the tool angles of the front and rear blades of a conical part of a conventional Christmas cutter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Christmas cutter 11 Tool shank 12 Screw part 13 Body part 14 Root taper part 15 Constriction part 16 Conical part 17 Right twist blade 18 Left twist blade 19 Chip discharge groove 19a Right twist groove 19b Left twist groove W Work S Processing groove

Claims (5)

[Claims] 1. A cutting blade of a conical portion of each stage is constituted by a right twist blade and a left twist blade, and two types of cutting blades are provided. A Christmas cutter characterized in that the blades are on the rear side, and the left blade cutters are arranged alternately in a circumferential direction in a zigzag manner so that the left twist blade is on the front side of the conical portion and the right twist blade is on the rear side. 2. A cutting edge at the rear side of the conical portion is extended to form a constricted portion cutting edge connecting the conical portions with the extended portion. 2. The Christmas cutter according to claim 1, wherein a front cutting edge is connected. 3. The cutting edge on the front side and the cutting edge on the rear side of the conical portion and the cutting edge on the constricted portion are each three pieces, and the rake angle of each cutting edge is 6 °.
Before and after the torsion angle of the cutting edge on the front side of the conical part of each stage is approximately 25.
3. The Christmas cutter according to claim 2, wherein the twist angle of the cutting edge on the rear side is set to 20 ° to 35 °. 4. The Christmas cutter according to claim 1, wherein the end of the front cutting edge of each conical portion is disposed behind the starting end of the rear cutting edge. 5. A cutting blade provided on a conical portion bulging radially outward at a tip end of a main body is constituted by a right twist blade and a left twist blade.
For the right blade cutter, the right twist blade is on the front side of the conical section, the left twist blade is on the rear side, and for the left blade cutter, the left twist blade is on the front side of the conical section, and the right twist blade is on the rear side. A blade groove characterized by being arranged in a staggered manner in the circumferential direction alternately in a circumferential direction, and the cutting edge on the rear side of the conical portion is connected to the cutting edge of the straight portion provided continuously behind the conical portion. Cutter.