JP5380746B2 - Cutting tools - Google Patents

Description

  The present invention relates to a turning cutting tool in which a cutting edge is formed of a hard sintered body such as a cBN sintered body or a diamond sintered body, and particularly to a cutting tool provided with a chip breaker on a rake face of a corner portion.

  A cutting tool in which a hard sintered body such as a cBN sintered body is bonded to a corner portion at the tip of a cemented carbide tool body, and a cutting edge and a chip breaker are formed on the hard sintered body is disclosed in Patent Documents 1 and 2 Is disclosed.

  This type of cutting tool is subjected to edge treatment for improving the strength of the edge portion on the upper surface of the tool body and the ridge line portion on the upper surface of the hard sintered body constituting the cutting edge. The cutting edge reinforcing chamfered part and the edge reinforcing chamfered part (for example, the cutting edge reinforcing chamfered part 6 and the chamfered part 8 having a height H in Patent Document 1) formed by the processing have a common angle. Many of them are formed on a common surface.

  The cutting tool of Patent Document 1 is configured by a breaker bottom surface provided by dropping a chip breaker from the upper surface of a hard sintered body and a breaker wall rising from the breaker bottom surface, and the breaker wall extends in a uniaxial direction. It is formed by a single surface of a cross-section arc.

  Moreover, the cutting tool (throw away tip) of patent document 2 comprises a breaker wall with a pair of 1st breaker wall and a pair of 2nd breaker wall connected to the outer end of the 1st breaker wall, The first breaker wall is formed into a wall having an inclination of the first obtuse angle θ1 with respect to the bisector of the apex angle of the tip corner portion, and extends from the position of the bisector to the left and right. This breaker wall is a wall having an inclination of a second obtuse angle θ2 larger than the first obtuse angle θ1 with respect to the bisector of the apex angle.

Japanese Patent Laid-Open No. 08-155702 JP 2006-95620 A

  The cutting tool disclosed in Patent Document 2 can reduce the breaker width as compared with the tool disclosed in Patent Document 1. If the width of the breaker is reduced, chips having a small width or thickness generated when the cut or feed during processing is small will also collide with the breaker wall. Therefore, the cutting tool of Patent Document 2 is trying to improve chip disposal in finishing or the like that is difficult to handle with the cutting tool of Patent Document 1.

  However, the cutting tool of Patent Document 2 does not give consideration to control of the flow direction of chips, and does not necessarily guarantee stable cutting.

  In the cutting tool of Patent Document 2, it is considered that the first breaker wall faces substantially perpendicular to the direction of chip discharge. In that case, if the chips reliably collide with the first breaker wall, a strong curling force is applied, and the chip breaking property is improved.

  However, in the structure of Patent Document 2, since the chip breaker is formed in the chamfered portion for edge reinforcement (7 in FIGS. 1 and 2 of the same document), the height of the breaker wall is sufficiently secured. Is difficult. Therefore, there is a concern that the chips do not collide well with the breaker wall and run on the chamfered portion and extend long in the rearward direction of the tool.

  Moreover, even if the height of the breaker wall can be secured to some extent, the breaker wall facing substantially perpendicular to the chip discharge direction does not have a function of controlling the chip discharge direction. For this reason, when the breaking distortion due to the breaker wall is insufficient, there is a possibility that the chips do not break and extend long along the breaker wall toward the rear of the tool feeding direction.

  The present invention relates to a cutting tool having a chip breaker, and an object of the present invention is to reliably and satisfactorily treat chips generated by small cutting and small feed processing for further stabilization of cutting processing.

In order to solve the above problems, in the present invention, a hard sintered body is joined to a seat groove formed in a corner portion at the tip of the tool body, and an arc corner cutting edge is joined to the hard sintered body. In a cutting tool in which a chip breaker comprising two straight cutting edges for a front cutting edge and a side cutting edge extending from both ends of a corner cutting edge, and a breaker wall and a breaker bottom surface,
The breaker wall is composed of a breaker main wall disposed closer to the center of the corner portion and one or more breaker subwalls connected to the outer end of the breaker main wall at an angle,
The main wall of the breaker is oriented in a direction perpendicular to the bisector of the apex angle of the corner portion in plan view of the tool (tilt angle 90 °), or the second angle of the apex angle of the corner portion Tilt in a direction that makes an obtuse angle to the segment,
When the cutting tool is tilted so that one of the straight cutting edges has a front cutting edge angle set in actual machining with respect to a straight reference line, a position where the corner cutting edge comes into contact with the reference line is determined. A point,
A point where a virtual line arranged parallel to the reference line and separated from the reference line by 0.3 mm or less intersects the corner cutting edge as a point B,
The breaker main wall faces the area connecting the points A and B,
The distance L1 from the point A to the breaker main wall and the distance L2 from the point B to the breaker main wall satisfy the condition of L2> L1 and the distance L1 is set to 0.2 mm or less. .

  The straight reference line mentioned here assumes a surface after machining of the workpiece. The distances L1 and L2 are represented by the distance in the C direction perpendicular to the straight line connecting the points A and B. The C direction distance from the point A to the breaker main wall is L1, and the C direction distance from the point B to the breaker main wall is L2.

  The breaker wall preferably has a height H of 0.2 mm or more.

  The breaker wall may be provided symmetrically with respect to the bisector of the apex angle of the corner portion.

  Moreover, the cutting tool of this invention can be comprised as a rhombus insert (throw away tip) which has the said corner part in a diagonal position, or an equilateral triangle insert provided with the said corner part three places.

  According to the cutting tool of the present invention, the flow direction of chips is controlled in a desired direction by the breaker main wall. The desirable direction refers to, for example, the outer side in the radial direction of the workpiece (side with the side cutting edge) in the outer diameter cutting.

  Since the distances L1 and L2 are set such that L2> L1, the generated chips reach the breaker main wall before the portion flowing out from the point A flows out from the point B. Thereby, a difference arises in the outflow resistance of the part which flows out from the A point of a chip, and the part which flows out out of the B point side, and a chip is induced | guided | derived to the B point side with small outflow resistance.

  For this reason, the chips do not flow away from the workpiece in the above-mentioned desirable direction, extend backward in the feed direction of the tool, become entangled with the tool, or damage the processed surface of the workpiece. Moreover, the distortion direction which curls with respect to a chip | tip is given because the outflow direction of a chip | tip becomes a desirable direction, and the cutting | disconnection process of a chip | tip will also be made favorable.

  The reason why the distance from the reference line to the virtual line for determining the point B is 0.3 mm or less is that the maximum cutting depth assumed in the finishing process is approximately 0.3 mm, and in the cutting under the cutting conditions. This is because the condition of L2> L1 is maintained.

  The distance L1 at the point A is set to 0.2 mm or less for the following reason. The finishing process is generally performed under the condition that the feed amount is 0.2 mm / rev or less. The breaker width should be about the same as the feed amount, and if the maximum value of the distance L1 at point A is set to 0.2 mm, the finishing process at the maximum feed amount (0.2 mm / rev) This is because the outflow part from the point A of the chips can be surely collided with the breaker main wall.

  With the above settings, there is an effect that guides chips to the B point side even in finishing with small cuts and small feeds, so that the chip can be treated reliably and satisfactorily, and the purpose of further stabilizing the cutting process is Achieved.

The perspective view which shows one form (reference product) of the cutting tool of this invention Enlarged perspective view of a corner portion involved in cutting of the cutting tool of FIG. Expanded cross section of breaker main wall FIG. 1 is an enlarged plan view of a corner portion involved in cutting of the cutting tool of FIG. Explanatory drawing of chip inducing action by breaker main wall The perspective view which shows the other form (this is also a reference product) of the cutting tool of this invention The perspective view which shows the other form (same reference product) of the cutting tool of this invention The perspective view which shows one form of the cutting tool of this invention FIG. 8 is an enlarged plan view of a corner portion involved in cutting of the cutting tool of FIG. Enlarged plan view of the known chip breaker shape used in the chip treatment comparison test The figure which shows the shape of the chip obtained by the comparative test of chip disposal

  Embodiments of a cutting tool according to the present invention will be described below with reference to FIGS.

1 to 4 show an example in which the present invention is applied to a diamond-shaped insert (throw away tip) (these are reference products, not invention products) . This insert 1 joins the hard sintered body 3 to the corner part of the front-end | tip of the tool main body 2, and makes the hard sintered body 3 participate in cutting.

  The illustrated tool uses a diamond-shaped base metal made of cemented carbide as the tool body 2. A seat groove 4 is provided at an acute corner portion at a diagonal position of the tool body 2, and a hard sintered body 3 such as a cBN sintered body or a diamond sintered body is bonded to the seat groove 4 to perform the hard sintering. A cutting edge 5 and a chip breaker 6 are formed on the body 3.

  The cutting edge 5 includes an arc corner cutting edge 5a and two straight cutting edges 5b and 5b extending from both ends of the corner cutting edge 5a. The straight cutting edge 5b is a cutting edge having a straight line at least in plan view, and the end may be cut toward the upper surface of the hard sintered body 3 as shown in FIG. One of the straight cutting edges 5b is used as a front cutting edge, and the other is used as a side cutting edge.

  The chip breaker 6 includes a breaker wall 6a and a breaker bottom surface 6b. The breaker bottom surface 6b is provided along the cutting edge. The illustrated breaker wall 6a is formed by a surface that rises obliquely from the bottom surface 6b of the breaker.

  In the illustrated cutting tool, in order to eliminate the right and left discrepancies, the bisector CL of the apex angle of the acute corner portion that causes the breaker wall 6a and the breaker bottom surface 6b to participate in cutting (see FIGS. 4 and 5) It is provided symmetrically on the border.

  The breaker wall 6a is composed of a breaker main wall 6am disposed near the center of the acute corner portion and a breaker subwall 6as connected to the outer end of the breaker main wall at an angle. The breaker subwall 6as may be formed by connecting a plurality of walls with an angle.

Breaker main wall 6am are both breaker angle α shown in FIG. 4 (angle which relative to the bisector CL of the apex angle of the corner portion) walls forming an obtuse angle, the breaker angle α of 90 ° of the wall I will do it. The breaker main wall 6am intersects at an acute angle with respect to the bisector of the apex angle is a reference product. This reference product and the tool of the present invention differ only in the breaker angle α.

    It is important that the breaker main wall 6am satisfies the following conditions, and the object of the invention is achieved by providing a breaker main wall that satisfies the conditions.

The conditions referred to here are the following I) to III).
I) When the cutting tool is inclined so that one of the straight cutting edges 5b has a predetermined angle (the front cutting edge angle λ when using the tool) with respect to the straight reference line S1, as shown in FIG. The imaginary line S2 arranged at a position where the corner cutting edge 5a contacts the reference line S1 at point A, parallel to the reference line S1 and at a distance of 0.3 mm or less from the reference line S1 is the corner cutting edge 5a. The breaker main wall 6am is made to face the region connecting the points A and B, with the point intersecting with the point B.
II) A distance L1 in the C direction perpendicular to a straight line connecting the points A and B from the point A to the breaker main wall 6am, and a distance L2 in the C direction from the point B to the breaker main wall 6am, L2> Satisfy the condition of L1.
III) The distance L1 at point A is set to 0.2 mm or less.

  The point A is set on the corner cutting edge 5a near the intersection of the corner cutting edge 5a and the straight cutting edge 5b used as the front cutting edge. In the case of a cutting tool of general-purpose size, although depending on the clearance angle of the front cutting edge, it is considered that the point A is set in a range of about 0.1 mm even if the separation distance from the intersection is large.

  The height H of the breaker wall 6a shown in FIG. 3 is preferably secured to 0.2 mm or more. By doing so, the chips can be reliably collided with the breaker wall 6a.

  In addition, although the inclination angle (beta) (refer FIG. 3) of the breaker wall 6a was 45 degrees in the illustrated tool, it is not limited to this.

In addition, the illustrated cutting tool has no chamfered portion for edge strengthening and a chamfered portion for edge reinforcement formed at the intersection of the upper surface and the side surface of the hard sintered body and the tool body. The installation of the part can be performed arbitrarily. In particular, it is preferable to perform cutting edge processing with chamfering or R honing amount of 0.1 mm or less.

  In addition, the present invention is a diagram in which an equilateral triangular insert 1A as shown in FIG. 6 provided with three acute corner portions involved in cutting, and the apex angle of the acute corner at a diagonal position smaller than that of the insert of FIG. The present invention can also be applied to a diamond-shaped insert 1B as shown in FIG. The application target may be a cutting tool other than the insert.

  FIG. 5 is an explanatory diagram related to the chip inducing action by the breaker main wall 6am. In this figure, assuming that the virtual line S2 is the outer diameter surface before machining of the workpiece and the reference line S1 is the outer diameter surface after machining, the point A set on the corner cutting edge 5a is the outer diameter surface after machining of the workpiece. , B points to the outer diameter surface before processing.

  In this state, the front cutting edge angle λ is set to proceed with the outer diameter machining of the workpiece. The machining is performed by feeding the tool in the Y direction in the figure, and the hatched portion in the figure is scraped off while the work rotates once. f is the tool feed amount per rotation of the workpiece.

  Chips generated at that time are a position (point A in the figure) where the cutting edge comes into contact with the work surface of the workpiece (the outer diameter surface after machining in outer diameter cutting) and a position where the chip contacts the outer diameter surface before machining of the workpiece (point A). For example, it flows out in the C direction substantially perpendicular to the straight line (S3) connecting the points B).

  And the chip mainly collides with the breaker main wall 6am arrange | positioned ahead in the outflow direction. At this time, the side of the chips flowing out from the point A collides with the breaker main wall 6am before the side flowing out from the point B because the distance to the breaker main wall 6am is shorter than the side flowing out from the point B. For this reason, there is a difference in the outflow resistance between the side flowing out from the point A and the side flowing out from the B point. As a result, the chips are guided to the point B side where the outflow resistance is small, that is, the side cutting edge side.

  The breaker width W shown in FIG. 4 is usually defined by the distance in the direction perpendicular to the breaker wall from the cutting edge to the breaker wall. The substantial breaker width is represented by L1. In the present invention, since L1 is set to 0.2 mm or less, if the feed rate is 0.2 mm / rev or less, the outflow part from the point A of the chip flows out from the B point. It surely collides with the breaker main wall 6am before the portion.

  Further, in the cutting tool of the present invention, the breaker main wall 6am is provided as a wall that satisfies the condition of L2> L1, and the line S4 perpendicular to the breaker main wall 6am is perpendicular to the reference line S1 (see FIG. 5). The chip discharge angle θ1 (the angle formed between the chip discharge direction and the reference line S1) is larger than the inclination angle θ2. For this reason, there is a difference in the arrival time to the breaker main wall 6am on the side that flows out from the point A and the side that flows out from the point B, whereby the above-described induction action occurs reliably. Accordingly, good chip disposal performance is exhibited when used under conditions where the cutting depth is 0.2 mm or less. In addition, since the effect of this invention can be acquired if most of the chips collide with the breaker main wall 6am, a small part of the chips may hit the breaker subwall 6as.

In order to evaluate the chip disposal performance, a comparative test was performed. The cutting tools used in the comparative test are the following tool I (substitute product of the invention) and a comparative product.

Tool I : manufactured by Sumitomo Electric Hardmetal Co., Ltd. Model No .: CCGW09T308 throw-away tip (rhombic negative tip with apex angle of 80 ° formed by cBN sintered body), with the shape of FIG. A cutting tool with a chip breaker installed in a holder.
Comparative product: A cutting tool in which a conventional chip breaker shown in FIG. 10 is formed on the cutting edge portion based on a throw-away tip having the same model number as the tool I and mounted on a holder.

The tool I has a nose R of 0.8 mm, a front cutting edge angle λ of 5 °, a distance L from the point A to the breaker main wall L1: 0.06 mm, and a point B to the breaker main wall L2: 0. .21 mm, feed amount f: 0.1 mm / rev, cutting amount ap: 0.1 mm, chip outflow angle θ1: 77 °, breaker main wall inclination angle β: 45 °.

Further, the comparative product is the same as the tool I with respect to the inclination angle of the breaker wall 7 provided symmetrically with respect to the bisector of the apex angle of the nose R and the corner, and the breaker angle α is 50 °. This was used at the setting of the front cutting edge angle λ: 5 °.

Assuming that the distance from the reference line S1 to the virtual line S2 is set to 0.3 mm (this is the recommended maximum cutting amount ap) in FIG. 4 where the front cutting edge angle λ is 5 °, When the angle α is less than 70 °, the distances L1 and L2 in FIG. Therefore, the tool I used here satisfies the condition of L2> L1, and the comparative product does not satisfy the condition.

Cutting conditions in the evaluation test are as follows.
Work material: SCM415 round bar, hardness HRC60
Cutting speed V: 150 m / min
1) Combination of feed amount f: 0.1 mm / rev, cut amount ap: 0.1 mm 2) Combination of feed amount f: 0.15 mm / rev, cut amount ap: 0.1 mm 3) Feed amount f: 0. Combination of 15 mm / rev and cutting depth ap: 0.2 mm Cutting form: dry cutting, outer diameter processing

Regarding the feed amount f and the cutting amount ap, the processing under the condition 1) was performed only for the tool I , and the processing under the condition 2) was performed only for the comparative product.

As a result of this test, while the cutting with the tool I processed the chips well, the cutting with the comparative product extended the chips long toward the front cutting edge. The shape of the chips produced by the tool I and the comparative product is shown in FIG. As can be seen from this figure, the chips produced by the tool I are well processed by the breaker main wall even under machining conditions of a feed amount f: 0.1 mm / rev and a cut amount ap: 0.1 mm, and are finely divided.
On the other hand, the chips by the comparative product are not treated properly by the breaker wall even under the processing conditions of the feed amount f: 0.15 mm / rev and the cut amount ap: 0.2 mm, and extend without breaking. .

In the cutting tool disclosed in the above-mentioned Patent Document 2, the first breaker wall corresponding to the breaker main wall of the present application approximates the breaker wall of the comparative product used in the above evaluation test. It can be seen that the tool I is superior to the chip disposal performance as compared with the cutting tool.

  In addition, the cutting tool of this invention can be utilized not only for the outer diameter processing of a workpiece but also for the inner diameter processing and end surface processing.

DESCRIPTION OF SYMBOLS 1 Insert 2 Tool body 3 Hard sintered body 4 Seat groove 5 Cutting edge 5a Corner cutting edge 5b Straight cutting edge 6 Chip breaker 6a Breaker wall 6am Breaker main wall 6as Breaker bottom wall 6b Breaker bottom face CL Line S1 Reference line S2 Virtual line S3 Straight line S4 connecting point A and point B set on the corner cutting edge Line W perpendicular to breaker main wall W Breaker width α Breaker angle λ Front cutting edge angle β Inclination of breaker wall Angle θ1 Chip discharge angle θ2 Inclination angle of the line perpendicular to the breaker main wall with respect to the reference line

Claims (4)

A hard sintered body (3) is joined to a seat groove (4) formed in a corner portion at the tip of the tool body (2), and an arcuate corner cutting edge (5a) is connected to the hard sintered body (3). A chip breaker (6) comprising two straight cutting edges (5b, 5b) for the front cutting edge and the side cutting edge respectively extending from both ends of the corner cutting edge, and a breaker wall (6a) and a breaker bottom face (6b). In the cutting tool formed)
The breaker wall (6a) is connected to a breaker main wall (6am) disposed closer to the center of the corner portion and one or more breaker sub-walls (6as) connected to an outer end of the breaker main wall (6am) at an angle. Consisting of
The breaker main wall (6am) is oriented in a direction perpendicular to the bisector (CL) of the apex angle of the corner portion in plan view of the tool, or the second angle of the apex angle of the corner portion Tilt in a direction that makes an obtuse angle to the segment (CL),
When the cutting tool is tilted so that one of the straight cutting edges (5b) has a front cutting edge angle (λ) set in actual machining with respect to the straight reference line (S1), the corner cutting edge A position where (5a) contacts the reference line (S1) is point A,
A point where a virtual line (S2) arranged parallel to the reference line (S1) and at a distance of 0.3 mm or less from the reference line intersects the corner cutting edge (5a) as a point B,
The breaker main wall (6am) is faced to a region connecting the points A and B,
A distance L1 in the C direction perpendicular to a straight line (S3) connecting the point A and the point B from the point A to the breaker main wall (6am), and from the point B to the breaker main wall (6am) wherein the C direction of the distance L2, satisfy the conditions of L2> L1, and switch cutting tool sets the distance L1 to 0.2mm or less.   The cutting tool according to claim 1, wherein a height (H) of the breaker wall (6a) is 0.2 mm or more. The cutting tool according to claim 1 or 2 , wherein the breaker wall (6a) is provided symmetrically with respect to a bisector (CL) of an apex angle of the corner portion. The cutting tool according to any one of claims 1 to 3, wherein the cutting tool is configured as a rhombus insert having the corner portion at a diagonal position or an equilateral triangular insert having three corner portions.