JP2000126920A - Face milling cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a face milling cutter allowing a high-speed feed, capable of improving machining efficiency (Vf value), and capable of obtaining good finished surface roughness. SOLUTION: Each circular throwaway tip 8 is fitted to the tip of a cylindrical holder 5 inclinatorily in the two-axis direction so that the side face becomes a cutting face, and a cutting blade 13 having convex curves on the front view and the rotating direction view of a cutter is generated. Each holder 5 is advanced to the outer peripheral side from the central side of the cutter by a fastening screw, it is fastened by a wedge pressed-in between it and a cutter main body 1, and the reduction of fastening force by centrifugal force is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a face milling cutter capable of performing high-efficiency machining with high accuracy.

[0002]

2. Description of the Related Art Machining efficiency in milling is evaluated by Vf value (product of cutting speed V and feed f). Its Vf
In order to increase the value while obtaining excellent machining accuracy, Japanese Patent Publication No. 6-20657 discloses a triangular flat indexable insert having a cutting edge of a convex circular arc in plan view. We have proposed a front milling cutter mounted on the cutter body with the rake face oriented.

[0003] In this cutter, the cutting edge has a convex curve in both the front view and the rotation direction view of the cutter, and the bite to the workpiece gradually increases. It exerts the effect of restraining and reducing the generated heat by dispersing the cutting force. Further, since a cutting force is applied to the chip in a direction perpendicular to the thickness, the strength of the chip is high, and the chip can withstand cutting of a hard material. Furthermore, since the arc radius R of the cutting edge is very large, good finished surface roughness can be obtained even at high feed.

[0004] The finished surface roughness of the cut surface is R _max maxf ² /
Since 8R (R is the radius of the arc of the cutting edge) is obtained, it is necessary to increase the feed f to increase the above-mentioned Vf value even when a good finished surface roughness is required by increasing the radius of the arc of the cutting edge. Thus, the features of the cutter disclosed in the above publication are exhibited.

[0005]

The above publication discloses a structure in which a holder capable of adjusting the position in the axial direction of the main body is provided to adjust the position of the cutting edge, and the indexable insert is held by the holder. ing. In this case, the holder is bolted to the cutter body, but strong fastening is difficult with bolts, and there is a concern that the bolts may be loosened during use, leaving concerns about the reliability of the fastening.

As for the fixing of the holder, as shown in FIG. 6, there is also a method in which the wedge 10 is propelled by the tightening screw 11 and pressed into the space between the holder 5 and the cutter body 1. According to this method, the wedge effect is reduced. Can generate a strong clamping force. However, according to the fixing structure of FIG. 6 in which the wedge 10 is press-fitted from the outer peripheral side to the center side of the cutter body, a strong centrifugal force acts on the wedge 10 when the cutter is used at a high speed, and the direction of the centrifugal force is changed. Since the direction matches the direction in which the tightening force by the wedge is weakened, the fixing of the holder becomes unstable.

[0007] The above-mentioned publication describes that the cylindrical locator is rotated to change the rake angle in the radial direction of the cutting edge. However, there is no means for restricting the locator rotation amount, and the locator is fixed by bolts. In the technique disclosed in the publication, it is difficult to accurately set the rake angle in the radial direction, and the position after setting is also unstable.

[0008] Under such circumstances, the conventional cutter is restricted from further increasing the cutting speed, and it has been difficult to meet the demand for further increasing the Vf value.

In high-speed cutting, the cutting edge is easily moved, so that it is difficult to further improve the roughness of the finished surface.

Accordingly, an object of the present invention is to solve the above-mentioned disadvantages while utilizing the features of the front milling cutter disclosed in the above-mentioned publication, and to further increase the Vf value and the processing accuracy.

[0011]

In order to solve the above-mentioned problems, in the present invention, a face milling cutter is constructed as follows. That is, a circular throw-away tip having a mounting hole in the center is fixed to a support seat at a tip end of a cylindrical holder with a countersunk screw in a direction in which an upper surface is a flank and a side is a rake surface, and the holder is a front surface of the cutter body. And fixed to the cutter body with a wedge that is inserted into a circular hole parallel to the body axis provided on the outer periphery of the body and press-fit between the flat pressurized surface provided on the holder outer circumference and the cutter body. The wedge has a structure in which the width of the wedge is narrowed toward the outer end, and the wedge is configured to be propelled from the center side of the cutter toward the outer peripheral side with a tightening screw when the holder is fixed. The cutting edge constituted by the crossing ridge of the upper surface and the side surface inclined to the side and the outer peripheral side respectively draws a convex curve in the front view and the rotation direction view of the cutter.

As the throw-away tip, either a positive type in which the side surface intersects the upper surface at an acute angle or a negative type in which the side surface intersects at a right angle may be employed.

[0013]

According to the cutter of the present invention, the cutting edge has a convex curve in both the front view and the rotation direction view of the cutter, so that the bite to the work is gradually increased. The effect of suppressing chatter and reducing the generated heat by dispersing the cutting force can be obtained.

Further, since the chip is mounted in a direction in which the side faces become a rake face, the strength of the cutting edge is improved, and cutting of a hard material can be performed. Further, since the cutting edge having a large arc radius (generating arc blade) is generated by inclining the circular tip in the two axial directions, good finished surface roughness can be obtained even in high feed cutting.

In addition to the above, it has the following features. That is, since the holder is fixed with a wedge,
The operating force of the wedge propulsion screw can be amplified to generate a strong tightening force. In addition, since the direction of the wedge is reversed from that in the related art, as the centrifugal force acting on the wedge during cutting increases, the tightening force due to the wedge increases, and the fixing of the holder is stabilized.

Further, when the wedge for fixing the holder is replaced with a wedge having a different wedge angle, the holder rotates at the same angle as the change amount of the wedge angle, and the biting point of the cutting edge to the workpiece is displaced. Accordingly, the rake angle in the radial direction is determined by the wedge, and the setting of the rake angle in the radial direction is easily and accurately performed, and the angle after the setting does not fluctuate. This also contributes to the stabilization of the processing, so that the cutting speed can be made higher than before, and the Vf value can be further increased.

[0017]

1 to 5 show an embodiment of a front milling cutter according to the present invention.

FIGS. 1 to 3 show a cutter main body 1. A plurality of circular holes 2 for inserting a holder parallel to the axis of the main body 1 are provided at a constant pitch in an outer peripheral portion of the main body 1. . The circular hole 2 is located at a position where a part of the circular hole 2 is cut through a wedge insertion groove 3 provided on the outer periphery near the back surface of the cutter body 1.

An annular groove 4 concentric with the axis of the main body is provided on the outer periphery near the back surface of the cutter body 1. The circular hole 2 is a hole cut out from the front of the cutter body 1 into the annular groove 4. Has become.

Reference numeral 5 denotes a cylindrical holder that fits into the circular hole 2 and fits. The holder 5 is provided with a flat pressurized surface 6 shown in FIG. 3 on the outer periphery of the longitudinal middle portion, and a tip support seat 7 shown in FIG.

Numeral 8 denotes a circular indexable insert (positive type in the figure) fixed on the support seat 7 with a countersunk screw 9, and 10 in FIGS. 2 and 3 is incorporated into the wedge insertion groove 3 and tightened with a tightening screw. (This is a so-called W screw) 11 is a wedge for fixing the holder, which is propelled by the cutter 11 and press-fitted between the cutter body 1 and the holder 5, and 12 is a cutting edge position adjusting screw screwed into the center of the back surface of the holder 5. This blade position adjusting screw 12
An operation section is located in the annular groove 4 and can be operated from outside. When the screw 12 is operated, the holder 5 can be displaced in the axial direction with reference to the groove surface of the annular groove 4 receiving the tip of the screw to adjust the cutting edge position of the tip.

As shown in FIG. 4A, the throw-away tip 8 is appropriately inclined toward the rear of the cutter in the rotational direction (the direction in which the center of the upper surface is displaced rearward in the rotational direction of the cutter to produce a clearance angle). is there. The inclination angle γ in the same direction with respect to the axis Y parallel to the axis of the holder 5 is preferably in the range of 3 ° to 15 °. If γ is 3 ° or less, the cutting edge 13 formed at the intersection between the upper surface and the side surface of the chip 8 approaches a straight line, and the effects of reducing the impact force during cutting and reducing the generated heat are reduced. On the other hand, when γ is 15 ° or more, when the arc radius of the cutting edge 13 is reduced and a good finished surface roughness is required, high feed becomes difficult, and there is a problem in the strength of the cutting edge portion. .

As shown in FIG. 4B, the throw-away tip 8 is also appropriately inclined on the outer peripheral side of the cutter (in the direction in which the center of the upper surface is displaced toward the outer peripheral side of the cutter). Also in this case, the inclination angle δ with respect to the axis Y is preferably in the range of 3 ° to 15 °. If δ is too small or too large, the finished surface roughness will be adversely affected, making it difficult to increase the feed.

Next, the width of the wedge 10 is reduced toward the outer end so that the wedge 10 is propelled from the center of the cutter body 1 toward the outer periphery when the holder is fixed. In this case, the wedge 10 tends to move in the tightening direction due to the centrifugal force at the time of cutting, so that the holder fixing force does not decrease, and the machining is stabilized, and the cutting speed can be further increased.

FIG. 5 is an explanatory diagram of the operation when the wedge angle of the wedge 10 is changed. Here, the wedge 10 of FIG. 5A having a wedge angle θ is shown, and the wedge angle is θ ₁ (θ>
considered that replaced in FIG. 5 the wedge 10 (b) of the theta _1).
In this case, the holder 5 rotates clockwise (θ−θ ₁ ) ° from the position in FIG. 5A, and the biting point P of the cutting edge 13 with respect to the workpiece is displaced to the outer peripheral side of the cutter, and the radius of the cutting edge is changed. The direction rake angle changes. Therefore, the adjustment of the rake angle in the radial direction can be easily and accurately performed by replacing the wedge 10. Further, since the holder 5 is reliably prevented from rotating by the wedge 10, the fluctuation of the adjusted radial rake angle does not occur.

[0026]

As described above, in the front milling cutter according to the present invention, the circular indexable insert is inclined in two axial directions to generate a cutting edge having a convex curve in both the front view and the rotation direction of the cutter. So that the impact force during cutting can be reduced,
It exerts effects such as reduction of generated heat and improvement of finished surface roughness.

Further, since the throw-away tip is used with the side face being the rake face, the strength of the cutting edge portion is increased, and the cutting edge can withstand cutting of a hard material.

Further, since the holder is fixed with a wedge,
Strong tightening force can be easily generated. In addition, the direction of wedge propulsion when the holder is fixed is reversed from that of the conventional cutter, so that the holder tightening force does not decrease due to centrifugal force.
Stable cutting can be performed even at high speed rotation.

In addition, it is possible to easily and accurately change the rake angle in the radial direction by changing the wedge angle by replacing the wedge, and to further increase the stability of cutting by securely stopping the holder from rotating with the wedge. And V
The f-value can be further increased, which can contribute to a reduction in the cost of a processed product.

[Brief description of the drawings]

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

FIG. 2 is a partially broken side view of the cutter according to the first embodiment.

FIG. 3 is an enlarged sectional view taken along line III-III in FIG. 2;

4A is a diagram showing a tilted state of the throw-away tip in a direction of FIG. 1A. FIG. 4B is a diagram showing a tilted state of the tip in a direction of FIG. 1B.

FIG. 5 (a) is a diagram showing a biting point when the holder is fixed with a wedge having a large wedge angle; and (b) is a diagram showing a biting point when the holder is fixed with a wedge having a small wedge angle.

FIG. 6 is a view showing a general tightening direction of a holder by a wedge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cutter body 2 Circular hole 3 Wedge insertion groove 4 Annular groove 5 Holder 6 Pressurized surface 7 Tip support seat 8 Throw-away tip 9 Countersunk screw 10 Wedge 11 Tightening screw 12 Blade position adjusting screw 13 Cutting edge P Biting point

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsutoshi Yamane 1-1-1 Kunyokita, Itami City F-term (reference) in Itami Works, Sumitomo Electric Industries, Ltd. 3C022 HH01 HH05 HH06 LL02 MM02 MM06

Claims (1)

[Claims] 1. A circular indexable insert having a mounting hole in the center is fixed to a support seat at the tip of a cylindrical holder with a countersunk screw in a direction in which an upper surface is a flank and a side is a rake surface,
The holder is opened to the front surface of the cutter body, inserted into a circular hole parallel to the body axis provided on the outer periphery of the body, and pressed into a pressurized surface between a flat surface to be pressed provided on the outer periphery of the holder and the cutter body. The wedge is fixed to the cutter body, the width of the wedge is narrowed toward the outer end side, and the wedge is configured to be propelled from the center side of the cutter toward the outer peripheral side with a tightening screw when the holder is fixed, and the throw away is performed in a fixed state of the holder. The tip is inclined to the rear side and the outer peripheral side in the rotation direction of the cutter, so that the cutting edge formed by the intersection ridge of the upper surface and the side surface draws a convex curve in both the front view and the rotation direction view of the cutter. Front milling cutter.