JPH0321858Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a throw-away tip used for groove milling cutters, side milling cutters, flat milling cutters, metal saws, and the like.

(Prior Art) Conventionally, as a milling cutter equipped with a curved cutting edge, for example, the one shown in Japanese Patent Publication No. 51-23750 is known. This milling cutter has a chip brazed to the outer periphery of the cutter body, the chip is provided with an arcuate rake face and a flank face, and a curved peripheral cutting edge is provided at the intersecting edge of the chip.
Since this structure is a brazed type, if the cutting edge becomes worn or damaged, the entire cutter must be replaced, which is very uneconomical.
When a worn or damaged cutting edge is ground and reused, not only that cutting edge but also other cutting edges must be ground for leveling, which makes the grinding work very troublesome and increases maintenance costs. There were problems such as high costs.

(Purpose of the invention) The present invention was made to solve these conventional problems, and it has less wear and damage on the cutting edge, has excellent cutting performance, and can be easily attached to and removed from the cutter body. The present invention also provides a throw-away tip that is replaceable, easy to maintain, and economical to use.

(Structure of the device) The device has a reference surface for attachment to the cutter body on the back side of the tip, a relief surface with a predetermined relief angle on the left and right circumferential surfaces, and a pair of left and right rake surfaces on the front surface. This is a throw-away chip with a mounting hole in the center that penetrates from the front to the back, and both of the rake faces are symmetrical to each other and are convex curved surfaces that are part of a cylinder or cone. The radial rake angle of one rake face gradually increases from the bottom to the top. On the other hand, the other rake face is curved so that the axial rake angle gradually increases from the top to the bottom, and a curved edge is formed at the intersection edge between both rake faces and the left and right flanks. The outer cutting edge ridge is formed, the width of the projected plane of both rake faces is formed to be 1/2 of the chip width, and a rising surface in the chip tightening direction is formed at the boundary between both rake faces. This is a characteristic feature. Note that the above-mentioned curved shape of the outer cutting edge includes a combination of a narrowly defined curve and a straight line.

By using the throw-away tip with the above configuration, good cutting with less vibration and chatter can be performed at the curved outer circumferential cutting edge edge, and the tip can be used in reverse, improving economical efficiency.

(Example) Figure 1 shows an example of the proposed throw-away tip (hereinafter simply referred to as the tip).In order to make the shape of the tip easier to understand, the mounting hole in the cutter body is omitted in this figure. A rectangular block with six orthogonal faces is indicated by a two-dot chain line as the original chip shape A, and an example of the chip as a product is shown in FIGS. 2a to 2c.

In FIGS. 1 and 2, a chip 1 is made of a hard material such as cemented carbide or ceramic, and has a pair of left and right rake faces 11 and 12 formed on its front surface, and flank faces 13 and 14 on both left and right sides. It is formed. The left and right flanks 13 and 14 are inclined with a predetermined clearance angle γ ₀ with respect to the side surface of the chip original form A, and the upper and lower surfaces 15 and 16 are inclined with zero clearance angle with respect to the upper and lower sides of the chip original form A. It is perpendicular to the back surface 17, and this tip back surface 17 serves as a reference surface for attachment to the cutter body 3 (see FIG. 3).

Both of the rake faces 11 and 12 have a mutually symmetrical shape and are curved with a radius R using a point O (see FIG. 2 c) as a fulcrum, which is a predetermined distance L away from the upper and lower surfaces 15 and 16, respectively, and They are formed of cylindrical surfaces (or conical surfaces) that are inclined inwards toward each other with a predetermined rake angle α ₀ in the left-right direction.
Furthermore, the pair of rake faces 11 are formed so that the thickness of the chip gradually becomes thinner and the rake angle α ₀ gradually increases from the upper end to the lower end, and the other rake face 12 conversely extends from the lower end to the upper end. As the thickness of the chip gradually decreases, the rake angle α ₀ gradually increases. Three-dimensionally curved outer circumferential cutting edge edges 18 and 19 are formed at the intersection edges of these rake faces 11 and 12 and the left and right flank surfaces 13 and 14, respectively. In addition, the width of the projection plane of both rake faces 11 and 12 is formed to be 1/2 of the chip width,
A rising surface in the tip tightening direction is formed at the boundary between both rake surfaces 11 and 12.

In addition, a hole 20 for attachment to the cutter body 3 is formed in the center of the tip 1, penetrating from the front side to the back side thereof, and a dish-shaped counterbore surface 21 is provided at the opening on the front side of the hole 20. It is being

In addition, in the above chip, the upper and lower surfaces 15, 1
6 are inclined at a predetermined relief angle with respect to the upper and lower side surfaces of the chip original shape A, and linear side cutting edges are formed at the intersection edges 22 and 23 between the relief surfaces 15 and 16 and the rake surfaces 11 and 12. You can.

Examples in which the tip 1 having the above structure is used in a groove milling cutter are shown in FIGS. 3 to 5. Figures 3 to 5
In the figure, the cutter body 3 has a handle portion 31 for attachment to a machine tool at one end, and a plurality of tip attachment portions 32 are provided on the outer periphery of the tip. Each chip mounting portion 32 has a chip mounting surface 33 that supports the chip back surface 17, a chip seating surface 34 that supports one flank surface 13 or 14 formed on the side surface of the chip, and a chip top surface 15 or bottom surface 16 that supports the chip mounting surface 33. With the chip seat surface 35, the front of the tool rotation direction,
Chip pockets each opening radially outward, axially downward or upward are provided in a staggered arrangement and at irregular intervals (equal intervals may be used) in the circumferential direction,
A chip mounting screw hole 36 is provided in the center of the chip mounting surface 33.

Then, insert the chips 1 into each of the chip pockets, and place the back surface 17 of each chip 1 on the chip mounting surface 3.
3, one of the flank surfaces 13 or 14 is supported on the chip seating surface 34, and the upper surface 15 or the lower surface 16 is supported on the chip seating surface 35, respectively, and for example, the outer cutting edge ridge 19 (or 18) is made to protrude to the outer periphery of the cutter. In this state, each chip 1 is fixed to the cutter main body 3 using a fixing device 37 such as a hexagon socket head flat head bolt.
In this case, the above-mentioned surfaces 33, 34, and 35 are aligned in the cutter radial direction and axial direction so that a predetermined rake angle α, peripheral clearance angle γ, and side clearance angle β are formed when the chip 1 is installed. Leave it tilted.
The rake angle α, peripheral relief angle γ, and side relief angle β are arbitrarily determined depending on the material of the workpiece, cutting conditions, etc., respectively.

When cutting with the cutter described above, since the chips 1 are attached to the outer periphery of the cutter body 3 in a staggered arrangement, a wide groove can be cut with the small chips 1.
Further, since the outer cutting edge ridge 19 (or 18) is curved and its rake face 12 (or 11) is formed as a convex curved surface, in the early stage of cutting, the outer cutting edge 19 and the rake face 12 The cutting edge 19 bites into the workpiece with point or minute surface contact, and the entire outer cutting edge ridge 19 does not hit the workpiece surface at the same time.
The impact and cutting resistance at the initial stage of cutting are alleviated, and cutting starts smoothly. After that, the chips are cut while being curved into an arc shape that is convex with respect to the rotation direction by the outer circumferential cutting edge ridge 19 and rake face 12 that are convex with respect to the rotation direction, and the chips are not bitten in the cutting part. Also, rake face 12
Since the width is large, chip evacuation efficiency is increased,
Cutting force is significantly reduced. Particularly in interrupted milling, if the cutting resistance at the initial stage of cutting can be reduced as described above, vibration and chatter will be reduced, cutting will be performed extremely smoothly, and wear and damage to the outer cutting edge ridge 19 will also be reduced.
This means that the chip life can be extended.

Furthermore, two outer cutting edges 1 are provided on the tip 1.
8 and 19, and since the tip 1 is detachably attached to the cutter body 3, one of the outer cutting edge ridges 19 or 18 of the tip 1 may wear out or If damaged, the chip 1 can be used repeatedly by reversing the chip 1 and using the other peripheral cutting edge 18 or 19, and also if the peripheral cutting edge 18 or 19 is worn or damaged. In such a case, only that particular chip 1 needs to be replaced, making it very economical to use.

(Effects of the invention) As described above, the present invention has a curved peripheral cutting edge with a rake face consisting of a curved surface that is convex in the direction of rotation, resulting in extremely smooth cutting with less cutting resistance and less vibration and chatter. In addition to reducing wear and damage on the cutting edge, it can extend the life of the chip.Furthermore, each chip has two curved cutting edges on the outer periphery, so one of the outer periphery If one cutting edge becomes worn or damaged, the chip can be reversed to use the other peripheral cutting edge;
It is easy to attach and detach the tip from the cutter body and to replace it. Furthermore, the structure is simplified by increasing the width of the rake face, making it easy to manufacture, improving chip evacuation efficiency, and re-grinding the cutting edge, making it extremely economical. It can be used.

[Brief explanation of drawings]

Fig. 1 is an enlarged perspective view showing an example of the chip of the present invention with the mounting holes omitted for the cutter body, and Figs. Figure 3 is a front view showing an example of the use of the chip, Figure 4 is a partially cutaway bottom view,
FIG. 5 is a developed side view in the circumferential direction for explaining the positional relationship of the chips. 1... Throwaway tip, 3... Cutter body, 11, 12... Rake face, 13, 14...
Flank surface, 15, 16... Upper and lower surfaces (flank surface), 1
7...Back.

Claims (1)

[Scope of utility model registration request] The back of the tip has a reference surface for mounting to the cutter body, the left and right circumferential sides and the top and bottom circumferential sides each have a relief surface with a predetermined clearance angle, and the front side has a pair of left and right rake surfaces, and the center part has a This is a throw-away chip with a mounting hole penetrating through the back surface, and both of the rake faces are symmetrical to each other and are formed as convex curved surfaces made of a part of a cylinder or cone, and are curved in the width direction of the chip. The rake faces are formed so that they are inclined inwards from each other with a predetermined radial rake angle, and one rake face is formed such that the axial rake angle gradually increases from the bottom to the top, and the other rake face is formed such that the axial rake angle gradually increases from the bottom to the top. Conversely, the face is formed so that the rake angle in the axial direction gradually increases from the upper part to the lower part, and a curved peripheral cutting edge ridge is formed at the intersection ridge of both rake faces and the above-mentioned left and right flanks. A throw-away chip characterized in that the width of the projected surface of the rake face is formed to be 1/2 of the width of the chip, and a rising surface in the chip tightening direction is formed at the boundary between the two rake faces.