KR20060135211A - Cutting insert - Google Patents

Abstract

A cutting insert is provided to improve processing accuracy by forming a stepped part between a rake surface and a mounting surface, to increase strength by forming the inclined or rounded stepped part, and to extend the life span by forming a recessed surface in an auxiliary cutting side. A polygonal cutting insert(100) includes a cutting blade(105) formed in an upper surface(120) or a side, a rake surface(130) inclined downward from the cutting blade to a center of the upper surface to discharge cut chips, and a stepped part(140) formed between the rake surface and the center of the upper surface. The inclination angle of the stepped part is larger than the downward inclination angle of the rake surface and smaller than the right angle. The stepped part is rounded, and a projection is formed in the rake surface near the stepped part to reduce the discharge diameter of the cut chips.

Description

Cutting insert

1 is a perspective view of a conventional double-sided cutting insert.

FIG. 2 is a front view of the cutting insert shown in FIG. 1. FIG.

3 is a perspective view of a milling cutter equipped with a cutting insert shown in FIG.

4 is a perspective view showing a cutting insert according to an embodiment of the present invention.

5 is a plan view of the cutting insert shown in FIG.

FIG. 6 is a side view of the cutting insert shown in FIG. 4. FIG.

FIG. 7 is a front view of the cutting insert shown in FIG. 4. FIG.

FIG. 8 is a schematic cross-sectional view taken along the line AA ′ of FIG. 4; FIG.

9 is a sectional view showing another embodiment of the cutting insert shown in FIG.

10 is a perspective view showing a cutting insert according to another embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100: cutting insert 105: cutting edge

106: auxiliary cutting edge 107: cutting part

110: seating surface 120: upper surface

125: lower surface 130: rake surface

131: protrusion 135: fastening hole

140: step portion 170: main cutting side

180: auxiliary cutting side 185: recessed surface

The present invention relates to a cutting insert for use in a cutting tool, and more particularly, to a cutting insert for easy milling.

In general, milling refers to processing steel or cast iron by a cutting insert coupled to a cutting tool including a rotating cutter, and the cutting insert (hereinafter referred to as 'insert'). Is usually made of cemented carbide.

Such inserts generally have a polygonal shape and are provided with cutting edges that cut only between the side surfaces and the top surface, so that only one side is used. In recent years, inserts capable of using both sides have been proposed.

Hereinafter, a conventional double-sided insert will be described with reference to FIGS. 1 to 3.

As shown in Figs. 1 and 2, a conventional double-sided insert 1 comprises an upper surface 2 and a lower surface 3 serving as a reference surface, and includes four surrounding upper and lower surfaces. It consists of sides (4).

Here, the lower surface 3 and the upper surface 2 are cross-symmetrical with respect to the virtual horizontal surface 14 of the center of the lower surface and the upper surface, so that after machining through the upper surface After turning the insert over, it becomes a double-sided insert that can be machined through the bottom surface.

On the other hand, the cutting edge (5) is formed at the intersection of the upper surface (2) and the one side of the insert (1), the auxiliary cutting edge (6) is formed on the side adjacent to the upper surface and the one side Thus, one cutting unit 7 is formed.

Therefore, the insert shown in FIGS. 1 and 2 has a pair of cutting portions 7 formed by the upper surface and two adjacent sides and a pair of other cutting portions formed by rotating 180 degrees around the fastening hole in the cutting portions. (7) is provided. In addition, the insert lower surface and two side surfaces adjacent to each other are provided with two cutting parts, respectively, and four cutting parts are provided as a whole.

Further, a rake surface 8 is further provided between the cutting portion and the center of the insert to discharge chips processed as a predetermined angled surface.

In the insert 1, a fastening hole 9 penetrating vertically through the upper and lower surfaces is formed in parallel with the shaft 11, and the shaft 11 is perpendicular to the virtual plane 14. In addition, a constant horizontal surface is formed around the upper surface and the lower surface on which the fastening hole is formed, and the horizontal surface becomes a seating surface 10 seated on the milling cutter.

3 is a perspective view illustrating that the cutting insert is coupled to a milling cutter of a cutting tool, and as shown in FIG. 3, the insert 1 has a predetermined angular interval at an outer periphery of the milling cutter 20. It is seated on the insert seating portion 22 provided in the pocket 25 formed.

Thereafter, the insert 1 is fixedly coupled to the milling cutter 20 by tightening a screw in the fastening hole 9 formed in the insert and the female screw part 26 formed in the insert seating portion.

On the other hand, since the insert is subjected to a force to rotate around the fastening hole during processing, two auxiliary seating portions 23 are formed inside the pocket to suppress rotation of the insert, and the auxiliary seating portion is Adjacent two side portions of the insert that are not cut are seated.

Here, the seating surface 10 on which the insert is seated is inclined by an angle in the rotational direction with respect to the rotation axis 21 of the milling cutter 20, and the value of a is about 4 degrees to a negative angle. Has That is, the seating surface of the insert 1 is mounted to the milling cutter in a state inclined at a predetermined angle with respect to the axis of rotation of the cutting tool. Due to this, the side provided with the auxiliary cutting edge of the insert has a positive clearance angle with respect to the workpiece, in order to allow a machining allowance.

After the insert 1 is fixedly coupled, the milling cutter 20 rotates in the R direction with respect to the rotation axis 21, and includes a cutting part 5 formed of the cutting edge 5 and the auxiliary cutting edge 6 of the insert ( 7) the workpiece is cut.

The conventional double-sided insert has a problem that the chip discharged on the cutting edge and the rake surface is in contact with the mounting surface on which the insert is seated, thereby lowering the level of the mounting surface. In addition, a phenomenon in which the chip accumulates on the seating surface occurs and, in the end, the machining accuracy is lowered when the insert is turned over and processed through another surface. It was more severe when abrasion resistant coatings were applied.

Of course, the conventional insert shown in Figs. 1 and 2 is provided with a rake surface in which the cutting edge is diagonally formed with respect to the horizontal surface on which the insert is seated. Therefore, the rake surface is provided so that the distance between the cutting part and the seating surface is reduced to reduce the influence of the cut chip on the seating surface. However, in this case, there was a problem in that it was not sufficient to meet the precision required for milling. .

On the other hand, the conventional insert is inclined at a predetermined negative angle (a) in order to allow the machining tolerance as shown in FIG. 3 so that not only the reaction force in the tangential direction to the insert during machining, but also the rotation axis direction of the cutting tool ( 21), the reaction force is generated, the stability of the insert during the machining and the machining accuracy is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a cutting insert which can be used on both sides to increase the service life and to increase the machining precision.

In order to achieve the above object, the present invention provides a cutting insert having a polygonal shape consisting of an upper surface, a lower surface comprising a seating surface seated on a cutting tool and sides surrounding the upper surface and the lower surface, A cutting edge provided between at least one of the upper surface and the side surfaces, a rake surface provided to be inclined downward from the cutting edge toward a central portion of the upper surface, and a cut chip is discharged; and the rake surface and the upper surface It comprises a stepped portion provided between the center of the, the inclination angle of the stepped portion provides a cutting insert, characterized in that it is formed larger than the downward inclination angle of the rake surface at the same time or less.

Here, the step portion is preferably formed in a round shape in order to increase the strength of the cutting portion. In addition, the predetermined portion of the rake surface close to the step portion is preferably provided with a projection to reduce the discharge radius of the cut chip.

In order to enable the cutting insert to use both the upper surface and the lower surface, the upper surface and the lower surface is preferably made of cross symmetry with each other on the basis of the virtual horizontal plane of the center of the upper surface and the lower surface, the cutting insert The central portion of the fastening hole for coupling with the cutting tool is preferably provided.

On the other hand, the cutting insert may be formed in a square shape consisting of a pair of major cutting side forming the cutting edge and facing each other, and a pair of auxiliary cutting side forming the auxiliary cutting edge and connected to the cutting side facing each other. In this case, it is preferable that the length of the main cutting side is a rectangular shape longer than the length of the sub cutting side.

In addition, the center portion of the side of the secondary cutting is preferably provided with a recessed surface recessed a predetermined depth in order to reduce the positive tolerance angle.

The cutting edge is formed in an oblique shape with respect to the upper surface or the lower surface, it is preferable that the height of the stepped portion at the corner portion where the main cutting edge and the auxiliary cutting edge is connected.

On the other hand, the present invention provides a cutting insert is characterized in that the cutting edge is formed in an arc shape, the height of the stepped portion in the center portion of the cutting edge is the smallest rectangular shape to achieve the above object. Unlike the cutting insert described above, the cutting insert may be provided with a cutting portion at each of four corners of the upper surface and four corners of the lower surface.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of a cutting insert according to the present invention will be described in detail.

4 to 7 show a cutting insert according to an embodiment of the present invention, Figure 8 schematically shows a cross-sectional view taken along line AA 'of FIG.

First, the configuration of a cutting insert according to an embodiment of the present invention will be described in detail with reference to FIGS. 4 to 7.

The insert according to an embodiment of the present invention comprises an upper surface, a lower surface, a side, a cutting edge, a rake surface and a stepped portion.

Here, the side surface surrounds the upper surface and the lower surface, the shape of the insert of the present invention is determined according to the number of the side surfaces. 4 to 7 illustrate, for example, rectangular inserts having four sides, and which polygonal inserts are determined according to the number of the side surfaces.

The lower surface 125 includes a seating surface 115 on which the insert 100 is seated on the cutting tool. That is, when the insert is coupled to the cutting tool and mounted, a surface on which the insert is coupled and supported is formed, and the seating surface 115 preferably has a single plane. This is because a single plane is easy in the machining surface for insert manufacturing and cutter manufacturing, and it is easy to disperse reaction forces generated during cutting.

In addition, a cutting edge 105 is provided between the upper surface 120 and any one of the side surfaces 170, and the workpiece is cut through the cutting edge.

4 to 7 show, as an example, that two cutting edges 105 and two auxiliary cutting edges 106 are provided between the upper surface and the side surfaces. Here, the major cutting surfaces 170 forming the cutting edge 105 together with the upper surface 120 are formed to face each other, and the auxiliary cutting surfaces 180 are formed to face each other adjacent to the main cutting surfaces. The auxiliary cutting surface forms an auxiliary cutting edge 106 together with the upper surface.

The rake surface 130 is a surface from which the chips cut through the cutting edge 105 is discharged, and is inclined downward from the cutting edge 105 toward the center of the upper surface. That is, the rake surface 9130 is provided to be inclined downward at a predetermined angle with respect to the horizontal plane, such an angle has an angle of about 5 ° to 15 ° in order to have a positive axial angle (positive axial angle) during normal processing do.

Here, it is preferable that the recessed surface 185 recessed a predetermined depth is further provided at the central portion of the auxiliary cutting side surface 180. That is, the auxiliary cutting side 180 has a positive tolerance angle with the workpiece, and the insert is coupled to the cutting tool at a predetermined angle a (see FIG. 3) to have a positive tolerance angle.

However, as described above, the reaction force is generated in the axial direction 21 of the cutting tool as well as the reaction force in the tangential direction to the insert 100 during machining, thereby decreasing the stability of the insert during machining and the accuracy of machining. Therefore, it is desirable to minimize this angle.

Accordingly, the auxiliary cutting side 180 having a predetermined angle with the workpiece is not formed in a single plane, but a constant recessed surface 185 is formed, resulting in a possible area where the workpiece and the auxiliary cutting side 180 may interfere. It is possible to minimize. That is, by providing such a recessed surface 185, it is possible to further reduce the positive tolerance angle, through which the negative angle a coupled with the cutting tool is brought close to 0 ° to engage the insert and the cutting tool at a substantially right angle. It becomes possible.

In other words, it will be possible to form an axial inclination angle at which the insert and the cutting tool are coupled at approximately right angles.

The stepped portion 140 is provided between the central portion of the rake surface 130 and the upper surface 120. Here, the stepped portion may mean a portion where the height is changed based on a horizontal plane between a predetermined portion of the central portion of the rake surface and the upper surface, and may be referred to as a step portion forming a constant step.

The stepped portion 140 serves to minimize the chip discharged through the rake surface 130 to affect a predetermined portion of the central portion of the upper surface.

On the other hand, the insert according to the present invention provides an insert 100 that can be used on both sides. That is, the upper surface 120 and the lower surface 125 are preferably cross-symmetrical with each other based on the virtual horizontal plane 175 in the center, so that both surfaces can be used. Accordingly, the same mounting surface 110 as the mounting surface 115 provided on the lower surface is provided on the upper surface, and similarly, the cutting edge is also provided between the lower surface and the predetermined side surface.

Here, whether or not the stepped portion 140 is provided plays a particularly important role in improving the machining precision in such a double-sided insert. This is because the flatness or the horizontality of the seating surface seated on the cutting tool affects the geometric precision seated on the cutting tool, which directly affects the machining precision.

Therefore, in order to minimize the effect that the chip is cut and discharged to the seating surface (110, 115) located in the center of the upper surface or the lower surface it is preferable to further provide a stepped portion giving a constant step.

On the other hand, the insert according to the invention is preferably provided with a fastening hole 135 in the center to be coupled to the cutting tool. The fastening hole is formed perpendicular to the seating surfaces 110 and 115, through which the insert can be screwed to the cutting tool. Of course, it would also be possible to be secured by a wedge to the cutting tool.

When cutting, there is a very large reaction force on the insert. Therefore, the geometry of the insert as well as the material capable of withstanding the reaction force is important. To this end, the insert according to the present invention may have a rectangular shape having a rectangular shape in which the length of the main cutting side 170 is longer than the length of the auxiliary cutting side 180. That is, the longer the longitudinal direction of the main cutting edge that receives a greater reaction force when cutting to increase the area receiving the reaction force during the cutting will be more effective.

Then, the greatest reaction force is received at the portion where the main cutting edge 105 and the auxiliary cutting edge 106 of the cutting portion 107 are cut. Therefore, the cutting edge is formed in an oblique shape on the basis of the mounting surface formed in a horizontal plane on the upper surface or the lower surface, the stepped portion 140 is formed the largest in the corner portion where the main cutting edge and the auxiliary cutting blade is connected. This is preferable.

That is, through the configuration as described above, there is an effect that the strength of the cutting portion to be cut is reinforced, in the case of the square-sided double-sided insert is provided with a total of four cutting portions. In addition, the neighboring main cutting surface and the auxiliary cutting surface forming a cutting portion other than the cutting portion currently used for cutting are preferably mounted on the auxiliary seating portion of the cutting tool to support the insert.

Hereinafter, the shape of the stepped portion of the insert according to the exemplary embodiment of the present invention will be described in detail with reference to FIG. 8. 8 is a cross-sectional view taken along the line AA ′ of FIG. 5.

A cutting edge 105 is provided between the side surface 170 and the rake surface 130, and the rake surface is inclined downward by a predetermined angle c to have a positive axial angle with respect to the seating surface 110.

Here, the rake surface 130 is not continuously extended to the predetermined angle to the seating surface, it is preferable that the stepped portion is formed to form a difference in height between the rake surface and the seating surface.

On the other hand, the insert is subjected to a reaction force F1 during the cutting, so as shown in Figure 8, the thinnest step portion 140 is inevitably vulnerable to the reaction force.

Therefore, it is preferable not to form the step portion simply perpendicularly to the seating portion, but to form the step portion into a vertical shape in which a round having a predetermined radius R1 is formed in order to add flesh to the step portion.

It is also possible to form the stepped portion at a predetermined angle b without forming it vertically. Here, the inclination angle of the stepped portion is an angle obtained by subtracting the predetermined angle b from a right angle. In this case, as described above, the thickness of the stepped portion may be further increased than the case of simply forming the seating portion vertically. Of course, even when the stepped portion is formed at an angle minus the predetermined angle b, the stepped portion may be formed in a round shape having a predetermined radius.

Here, the predetermined angle b will be 0 ° when the inclination angle of the stepped portion is vertical, and when the stepped portion is not formed, it will be equal to the angle c of the rake surface. Therefore, it is preferable that the predetermined angle b is greater than 0 ° and smaller than the angle minus the angle c of the rake surface from the vertical.

By doing so, the inclination angle of the stepped portion may be made larger than the inclination angle of the rake surface and smaller than the vertical, thereby increasing the thickness of the insert in the stepped portion than the case of simply forming the inclined angle of the stepped portion only vertically. .

On the other hand, even when the inclination angle of the stepped portion is made vertical, if the stepped portion is rounded, the insert thickness at the stepped portion may be similarly increased.

9 shows another embodiment of the insert shown in FIG. 8. Here, the protrusion 131 is further formed on the rake surface 130. That is, when the chip 190 cut along the rake surface 130 is formed and discharged to have a constant radius R2, reducing the size of the radius may reduce the effect that the chip may have on the seating surface 110. It is a way.

Therefore, it is preferable that the protrusion part 131 is further provided at a portion proximate to the stepped portion without forming the rake surface only at a predetermined angle. The protrusion may be a horizontal portion horizontal to the seating surface, it may be formed to further protrude from the horizontal portion to the top. The protrusion may be configured as a curved portion having a predetermined radius.

Hereinafter, the use of the insert according to an embodiment of the present invention will be described in detail.

The insert according to the present invention is coupled to the milling cutter so that the cutting unit cuts the workpiece by the rotation of the milling cutter. That is, the workpiece is cut through the main cutting edge and the auxiliary cutting edge provided in the cutting portion, and the insert is separated from the milling cutter when the cutting edge is damaged due to prolonged use.

Thereafter, the cut for the engineer is seated in the auxiliary seating portion, and cut again through the unused cutting portion. On the other hand, in the case of processing through the cutting portion of any one of the upper surface or the lower surface it is possible to turn over the insert and cut again through the other cutting portion.

FIG. 10 illustrates another embodiment of the present invention, and a duplicate description of the same configuration as the above-described embodiment of the insert illustrated in FIG. 10 will be omitted and only the differences will be described in detail.

Another embodiment of the present invention shown in Figure 10 is a square square insert, it will be possible to insert a square polygon.

The cutting edges 205 and 206 of the insert 200 are formed in an arc shape as shown, and have the smallest height of the stepped portion in the center portion of the cutting edge. This is because the cutting portion 207 of the insert is formed in the corner portion relatively little cutting in the center portion of the cutting edge.

On the other hand, according to another embodiment of the present invention, since the cutting portion is formed at each corner, the rectangular double-sided insert shown in FIG. 9 includes eight cutting portions 207 as a whole.

Another embodiment of the present invention has the advantage that the cutting portion is more provided in the same shape as the above-described embodiment, but the ability to withstand the cutting force will be reduced.

The present invention is not limited to the above-described embodiments, and those skilled in the art can make modifications without departing from the spirit of the present invention, and such modifications are within the scope of the present invention.

In the above-described embodiment, only the case in which the insert is directly coupled to the milling cutter has been described. However, the present invention also includes an indexable type in which the cartridge is coupled to the milling cutter after the insert is coupled to the locator. Inserts may be used.

According to the present invention described above,

First, a stepped portion is provided between the rake surface and the seating surface on which the insert is seated on the cutting tool, thereby minimizing the effect of the cut chip on the seating surface, thereby providing a double-sided insert having improved processing accuracy.

Secondly, the stepped portion may be formed at a predetermined angle or in a round shape to provide an insert that reinforces the strength to the cutting force more than in the case of a simple vertical shape.

Third, a predetermined recessed surface is provided on the side of the secondary cutting, thereby reducing the angle at which the insert is coupled to the cutting tool, thereby providing an insert having improved machining precision and durability.

Claims (11)

In the cutting insert of the polygon shape consisting of an upper surface, a lower surface comprising a seating surface seated on the cutting tool and the sides surrounding the upper surface and the lower surface, A cutting edge provided at at least one position between the upper surface and the side surfaces; A rake surface provided to be inclined downward from the cutting edge toward the center of the upper surface to discharge the cut chips; And It comprises a stepped portion provided between the central portion of the rake surface and the upper surface, Cutting step characterized in that the inclination angle of the stepped portion is formed larger than the downward inclination angle of the rake surface and smaller than the right angle. The method of claim 1, Cutting step characterized in that the step is made in a round shape. The method of claim 1, The cutting insert, characterized in that the projection is provided in a predetermined portion of the rake surface close to the step portion to reduce the discharge radius of the cut chip. The method according to any one of claims 1 to 3, The upper surface and the lower surface is a cutting insert, characterized in that both sides of the cross symmetry with respect to the virtual horizontal plane of the center of the upper surface and the lower surface can be used. The method of claim 4, wherein Cutting insert, characterized in that the central portion of the insert is provided with a fastening hole for coupling with the cutting tool. The method of claim 5, The insert is A pair of major cutting sides forming cutting edges and facing each other; And Cutting inserts, characterized in that forming a secondary cutting edge, a square shape consisting of a pair of secondary cutting side surfaces connected to the main cutting side and facing each other. The method of claim 6, The insert is a cutting insert, characterized in that the length of the main cutting side is a rectangular shape longer than the length of the auxiliary cutting side. The method of claim 6, If the center portion of the side of the secondary cutting side is provided with a recessed surface recessed predetermined depth, cutting insert. The method of claim 8, The cutting edge is formed in an oblique shape with respect to the upper surface or the lower surface, the cutting insert, characterized in that the height of the stepped portion in the corner portion is connected to the cutting edge and the auxiliary cutting edge is the highest. The method of claim 5, The cutting edge is formed in an arc shape, the cutting insert, characterized in that the height of the stepped portion in the center portion of the cutting edge is the lowest square shape. In the cutting insert of the polygon shape consisting of an upper surface, a lower surface comprising a seating surface seated on the cutting tool and the sides surrounding the upper surface and the lower surface, A cutting edge provided at at least one position between the upper surface and the side surfaces; A rake surface provided to be inclined downward from the cutting edge toward the center of the upper surface to discharge the cut chips; And It comprises a stepped portion provided between the central portion of the rake surface and the upper surface, The stepped portion is a cutting insert having a round shape perpendicular to the seating surface.

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