DE7518516U - CUTTING INSERT WITH CHIP BREAKER - Google Patents

Description

Cutting insert with chip breaker

The invention relates to an attachable to a Werkζ eagschaft Cutting insert with at least one straight cutting edge which has a groove for diverting and influencing the chip, as well as with a rounded cutting tip.

Cutting inserts with chip breakers are usually triangular or square shaped, for example square, rectangular or rhombic, have at least one cutting tip, can be attached to a tool shank and are used for Machining of workpieces by diverting and preferentially removing chips.

The invention is particularly concerned with removable cutting inserts positive or negative shape with at least a cutting edge.

The term "chip breaker" refers to the change in orientation understood the cutting or rake face of the removable cutting insert, which causes the curling and breaking of the Spans is favored.

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Cutting tools have been manufactured for a long time, their Geometry was designed more and more so that the chip removed from the machined workpiece curl and then could break into small pieces that can be easily removed from the work surface. Wrap in the opposite case The chips formed during the cut move around the machined workpiece by a rotary movement and then jam in the machine, which permanently disrupts the functioning of the machine and creates a risk of injury to the operating personnel cause.

For this reason, one-piece cutting tools or cutting tools with a sonic plate soldered on are proposed first and have been used where the chip breaker was ground. With this method, however, it was difficult to obtain the To give chip breakers the most favorable shape for achieving a well-curling and easily breaking chip and to exactly restore the chip breaker mentioned by regrinding.

Because of the occurring in these first forms of training Difficulties, the use of removable cutting inserts has been proposed, generally by Sintering are produced and can be mechanically attached to a cutting tool shaft. It became possible that to define a new shape of a chip breaker for a cutting insert in advance and to ensure that it can be easily restored.

Numerous types have been proposed for chip breaker inserts. Among them is the first type of training a cutting insert, the chip breaker of which is designed in the form of a groove that runs along a cutting edge. However, such an insert was found to be difficult to perform a finishing operation as the chip breaker was designed for roughing work. Such a chip breaker thus produces during finishing

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long strip chips that disrupt the functioning of the machine tool.

With the aim of eliminating these identified major disadvantages, a cutting insert of a second design type was recommended, the one called with a secondary chip breaker second chip breaker was provided which completed the effect of the aforementioned chip breaker called the main chip breaker. The secondary chip breaker is arranged in this case in the cutting wedge of the cutting insert and can, for example be formed by vain further depression. It was For example, a triangular cutting insert is described which has three identical cutting wedges with cutting edges and lengthways this cutting edge was provided with main chip breakers. In each cutting die there is a secondary chip breaker, the forms a recess in the top of the insert and is deeper and narrower than the main chip breaker.

Even if this last-mentioned type of insert is basically brought an improvement with regard to the breaking of chips with a small cross-section, as they did with relatively small chips Shear depths arise, have major disadvantages in use exposed.

Most notably, the main and secondary chip breakers reveal a discontinuity of the contour lines in the active cutting surface, from which a functional one develops during chip formation Discontinuity results. Thus "exists depending on the angle of incidence of the cutting tip and depending on the type of machined Materials an ineffectiveness zone in which the removed chip is no longer in its entirety from the one or the other chip breaker is detected. This intermediate zone between the two chip breakers therefore does not play a role the fundamental role that could be assigned to it and creates poorly trained chips that are a source of interference for the good functioning of the machine tool. If the insert is used for roughing,

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a large chip is created, which is under the action of the main chip breaker breaks. If the insert is used for finishing at a shallow depth of cut, the through The rounded part of the cutting wedge creates narrow chips on the secondary chip breaker and breaks there. Dial +: man for However, if the cutting depth is an intermediate value, the removed chip runs partly on the main chip breaker, whereby the Secondary chip breaker does not play a role in the formation and management of the said chip. There is a tendency that more or less long ribbon chips are formed which disrupt the normal functioning of the machine tool.

Finally, if the main chip breaker on the removable insert results in a positive rake angle, becomes the cutting tip, which is subject to the highest mechanical and thermal stresses, due to its presence the second recess in the cutting wedge that forms the secondary chip breaker is particularly sensitive.

The object of the invention is to create a cutting insert which eliminates the aforementioned difficulties.

The solution to the problem of the invention has led to a cutting insert of the type described at the outset, which according to the invention from an essentially pyramid-shaped cutting surface, the generatrix of which forms a constant angle c * with the base plane containing the cutting edge, and from a plurality of levels is composed, the one Form another surface, called the chip breaker surface, on which the chip to be broken runs and which are arranged in such a way that that a hollow zone results in the rounded cutting tip, the lowest point of which is in the bisecting plane the cutting tip lies. This creates a preferred derivation of the chip.

The invention is illustrated below with reference to schematic drawings of an embodiment with further details

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explained. In the drawing shows:

Pig. 1 is a perspective view of the severed cutting tip and corresponding pyramid in side-by-side arrangement,

Fig. 2 is a perspective homogeneous view of the severed Aggregate of rounded cutting point and pyramid,

3 shows a vertical section through the cutting insert in engagement,

4 shows a view of the cutting insert in the horizontal plane according to the rules of the illustrative geometry,

5 shows a section in a ^{vertical plane passing through the line HH 1} in FIG.

6 shows a section in a ^{vertical plane passing through line BB 1} in FIG.

7 shows a representation of the contour lines drawn in one of the rounded tips of the cutting insert, and FIG

8 and 9 are top views of the cutting insert in engagement during a finishing or roughing operation.

In order to facilitate the description, the removable cutting insert is essentially the area of the grooved Looked at top. It goes without saying that the features indicated in their context also apply to the triangular removable ones Inserts like the square inserts with, for example, square, rectangular or rhombic ones Form.

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The one in Pig. 1, 2 and 3 shown removable cutting insert according to the invention has a cutting or rake face 1 on which the chip runs off and which can be divided into a pyramid-shaped part 2 and a rounded cutting tip 3 »further straight cutting edges 4, which in planes parallel to the support plane of the cutting insert, such as those contained in plane Qo (FIGS. 5 and 6), as well as three-dimensional cutting wedges. A triangular insert has three such wedges. A spatially designed cutting wedge is formed on both sides of the cutting edges 4 by a circumferential surface 6 referred to as a "free surface", possibly by a ^{surface 7 called "chamfer 1} , which does not play an active role in chip formation, but essentially reinforces the cutting edge 4 serves, limited by the cutting surface 1, on which the chip runs, and by a "chip breaker" axed and an obstacle for the chip-forming surface 8. The width of the bevel 7 is generally between 0 and 0.6 mm, but preferably ' between 0.1 and 0.3 mm.

In the event the insert lasts in terms of both is designed symmetrically by the cutting edges 4 and 5, can be used to reinforce the cutting edge 5, a chamfer 7 similar to chamfer 3 may also be present on the second surface.

The generatrix of the aforementioned cutting surface 1 forms with the plane Qo, the base plane containing the cutting edge 4 and the bevel 7, an angle ° C (FIGS. 5 and 6) which is constant over the entire length of the initial length of the cutting insert. The angle <* is referred to as positive if it is on the side of the free surface 6. The size of the angle <> C is generally between 2 and 30 °, but most advantageously between 5 and 20.

The removable cutting tip according to the invention also has a plurality of planes that form a chip breaker form. To facilitate the description of this chip breaker,

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becomes one of the cutting tips of the cutting insert according to the invention considered separately (Pig. 4, 5 and 6).

The surface of the chip breaker is defined by a plane P1 which, in the rounded tip of the cutting wedge (Fig. 5), forms an angle / 3 with the plane Qo and whose line of intersection with the reference plane Qo is shown in Fig. 4 by the straight line MN, which is perpendicular to the bisector of the cutting tip and has a distance from the cutting edge 4 corresponding to the distance HH '= dl. The straight line H1H 'projected onto the reference plane Qo is measured as section H1H ¹ = d2 and should at most be equal to the radius R of the cutting tip, iier point H1 is the intersection between the cutting surface, the plane P1 and the bisecting plane of the cutting tip.

The size of the angle / 3 can fluctuate within wide limits, for example between 15 and 90, but is preferably selected with a value between 30 and 60 °. The distance d1 should be between 0.625 R and 2R and can often be equal to R. The distance d2 is between 0.5 R and R ₄ ,

In particular, it has been found that the size of d2 is from the width d3 of the chamfer 7 and the radius R was dependent and through d3 essentially according to the relationship

d2 - IR + d3
ο

was conditional.

Likewise, the mentioned area of the chip breaker in the pyramid-shaped part 2 is delimited by the plane Q1, which is located from the plane Qo at a distance h which is selected to be between 0 and 0.20 mm, and by the planes P ¹ 2 and P "2, which form the same angle / ^ with the plane Qo (FIG. 6) and whose lines of intersection with the plane Qo in FIG. 4 are indicated by the straight lines FI and FK. These

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Cutting lines are generally symmetrical to the bisector of the cutting wedge and can be aligned with the cutting edge 4 form an angle <f, which is between 0 and 20 °, preferably but is between 5 and 15.

After the cut along the line BB ¹ (FIG. 6), in which the point B contained in the plane Qo is the intersection of the plane P "2 with MN and the plane P1 with the plane P" 2, the values of the section appear BB ¹ and the distance B1B * projected onto the plane Qo in the pyramid-shaped part 2. The size of the section BB 'is ^{measured with d 1} 1, where d'1 is between 0.5 R and R. Since the point B1 is the intersection of the cutting surface with the plane P "2 and the ^{section containing BB 1 , the distance B1B 1} projected onto the plane Qo is measured with the absoaneit d ^f 2, which is between 0.3 R and d2 .

This clearly shows that due to the symmetry with respect to the bisecting plane of the cutting tip, the values of d "1 and d" 2 can be measured ^{through sections AA 1} and A1A ^1.

The surface of the chip breaker can be limited in another way by a plane Q ¹ 1 (Fig. 5) which forms an angle ψ with the aforementioned plane Q1 and is perpendicular to the bisecting plane of the rounded cutting tip. The angle ψ , which is always smaller than the angle / 3, is between 0 and 60 °, but preferably between ο and 30 °.

It is clear that connect from basic manufacturing reasons, the surfaces described, both in the rounded tip 3 and the pyramid-shaped portion 2, generally with the radii R1, R ", R'2, R3, R ¹ 3 and R 4 to each other. The radii R1, R3, R ¹ 3 and R 4 may assume, in the case of sharp edges a value of zero and are not capped. the radius R2 which is generally equal to R'2 which ensures continuity of the cutting surfaces. It is

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in the section plane AA 'generally between 0.1 and 1 mm, however, it is preferably selected between 0.1 and 0.6 mm.

The planes P1, P ¹ 2 and P "2 were arranged so that the distances AA ¹ and BB ^{1 are} smaller than HH ^1. It follows that the theoretical depth P of the chip breaker at point H1 is greater than the theoretical depth P. ^{1 of the} same chipbreaker at points Ai and B1. It was also found that the depth P must be between 0.1 R and 0.4 R and the depth P ¹ between 0.05 R and 0.3 R.!, While j the difference between P and P ¹ must always be positive and at least equal to 0.05 R ^.;

The rounded tip therefore has a trough whose lowest point is on a vertical axis passing through point H1 and the effect of which is to remove the chips from small; measurements according to a limited by the plane P1 To direct generators of the cutting tip, whereby the chips accumulate at the said plane and are effectively broken.

However, when the chip cross-section becomes larger, that is the case removed metal approximately at right angles to the cutting edge and the chip breaker then operates in a conventional manner.

In the latter case, and if the apex of the angle f is directed towards the cutting tip, the drainage of the chip is facilitated, since P with increasing distance from the:

Cutting tip grows. In Fig. 7 of this phenomenon is the decision <development of the depth P by the totality of an interval of \ respectively 20 μια drawn contour lines clearly shown. ]

These contour lines allow the continuity of the only j

Recognize surfaces forming chip breakers. This chip breaker has no ineffectiveness zone and is both at

Roughing and finishing are effective. \

It is clear that the "open area" called circumferential surface 6 } of the cutting plate can extend at right angles to the top and bottom, which are parallel to one another. With such a

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Design of the cutting plate is provided with chip breaker surfaces on both sides, can be turned and offers thus twice the number of cutting edges than a non-reversible cutting insert. Forms the open space with the top If the insert has an angle smaller than 90 °, then this insert is for use in conjunction with a positive tool holder and cannot be turned. The cutting insert according to the invention is made of one hard and wear-resistant material, for example made of sintered hard metals or sintered ceramics.

EXAMPLE

For roughing and finishing, one designed according to the invention was used Insert of an equilateral triangle of similar shape and with a positive rake angle, accordingly the ISO, TPMR I6O38 standard is used. The technical data were as follows:

Angle * angle fi> angle J angle f segment HH ¹ = d1 ^{segment AA 1} = BB ¹ = d ^f 1 segment H1H ¹ = d2 segment B1B ¹ = d2 width of bevel 7 = d3 distance between planes Q1 and Qo = h radius the cutting point, R

R1 transition radii between the cutting surface and the surface of the chip breaker, R2 = R ¹ 2

R'3 R4 depth of the recess, in the cutting plane HH ¹ - P = 0.17 R

in the section plane 3B ¹ - P ¹ difference PP ¹

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0 10 0 mm 0 45 0 τη τη 0 10 O mi_ 0 0 O mm 0 ,8th mm t , 5 mm 0 , 6 mm 0 , 4 mm 0 ,1 mm 0 f 05 mm ,8th τητη 1 ,1 mm 0 , 3 mm 0 15th mm 0 0, 36 ,1 0, 036

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The material of the workpiece was steel XC45 f. The cutting insert was grade P20, according to ISO designation. The cutting speed was 120 ii./rain. External longitudinal turning was carried out on a lead screw lathe.

According to the ISO-TC.29-913F "Small tools" standard, the shape of the chips was dependent on the depth of cut and
investigated the feed. The examined chips showed the best conceivable characteristics, since they, according to shape, in flat
Spirals, conical spirals, short tubes and short ones
conical coils were incurred.

The results are summarized in the table below. The unchecked boxes represent the areas with excellent features of the chips obtained, which
crossed boxes for the rare cases in which the
Chips showed less good characteristics,

/Expectations

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Claims (11)

16-46 313 CLAIMS 1. Cutting plate attachable to a tool shank with at least one straight cutting edge, which has a groove for diverting and influencing the chip, and with one rounded cutting tip, characterized in that it consists of a substantially pyramidal cutting surface (1), the generatrices of which form a constant angle oi with the base plane (Qo) containing the cutting edge (4), and is composed of a plurality of planes which form a further surface (8) called the chip breaker surface, on which the chip to be broken runs up and arranged in this way are that there is a hollow zone in the rounded cutting tip (3), the lowest point of which in the bisector Level of the cutting tip (3). 2. Cutting insert according to claim 1, characterized in that the chip breaker surface (8) is defined by planes P1, P ¹ 2 and P "2 which form an angle / 3 with the base plane Qo and the planes Qo and Q1, the plane Q1 is at a distance of h from the ground plane Qo. 3. Cutting insert according to claim 1, characterized GEK e η η - characterized in that the angle oC generally between 2 and 30 °, but preferably between 5 and 20 °. 4th Cutting insert according to Claims 1 to 3f thereby characterized in that the angle / 3 between 15 and 90 °, but preferably between 30 and 60. / 2 7518516 12/18/75 - 2 - 4b 313 5. Cutting insert according to claims 1 to 4, dadv .-- 'fc. characterized in that the line of intersection between the plane P1 and the base plane Qo, measured in the bisector Plane of the cutting tip (3) with the radius R> at a distance d1 from the cutting edge (4) where d1 is between 0.625 R and 2 R, and that the intersection point H1 projected onto the ground plane Qo Cutting surface (1), the plane P1 and the bisecting plane of the cutting tip (3) at a distance d2 from the Cutting edge (4) lies, where d2 is between 0.5 R and R. 6. Cutting insert according to claims 1 to 4, characterized in that the point B as a cutting point of the planes Qo, P1 and P "2 \ n is a distance d'1 from the cutting edge (4), where d ¹ 1 between 0.5 R and R, and that the intersection point B1 projected onto the base plane Qo of the cutting surface (1), the plane P "2 and the cutting plane perpendicular to the cutting edge (4) and passing through the point B at a distance d ' 2 lies from said cutting edge (4), where d'2 is between 0.3 R and d2. 7. Cutting insert according to claims 1 to 6, characterized in that the distance h between the planes Qo and Ql parallel to one another are smaller or at most is equal to 0.2 mm. 8. Cutting insert according to claim 1, characterized in that the chip breaker surface (5) is defined by the plane Q'1 which forms an angle ψ with the base plane Qo which is between 0 and 60, but preferably between 0 and 3C. 9. Cutting insert according to claim 5, characterized in that the depth P of the point K1 with respect to the plane Qo is between 0.1 R and 0.4 R, that / 3 7518516 12/18/75 46 313 ζ the depth P ^{f of} the point B1 is between 0.05 R and 0.3 R, and that the difference PP 'is at least 0.05 R. 10. Cutting insert according to claims 1 to 9, characterized in that the intersection lines of the planes P ¹ 2 and P "2 with the base plane Qo with the cutting edge (4) form an angle ff which is between 0 and 20 °, but preferably between 5 and 15 °. 11. Cutting insert according to claims 1 to 10, characterized in that the width of the bevel (7) between 0 and 0.6 mm, but preferably between 0.1 and 0.3 now. 7518516 12/18/75