JP6792955B2 - Cutting tools - Google Patents

Description

The present invention relates to a cutting tool capable of prolonging the tool life.

For machine parts and the like that require precision, cut products obtained by cutting work materials such as castings and metal materials are used. In order to manufacture (process) high-quality cut products at low cost, it is important to improve machinability and prolong the tool life.

Especially when cutting difficult-to-cut materials (for example, Ti-based materials, Ni-based materials, etc.), the cutting heat generated causes the cutting tool (chip) to reach a considerably high temperature, resulting in thermal wear (one of the tool wear mechanisms). ), The tool life tends to be shortened. A description related to this is found in, for example, Non-Patent Document 1 below.

From this point of view, for example, Patent Document 1 below has proposed to improve the supply of the machining fluid (coolant) used during machining to the cutting edge (machining point) to extend the life of the cutting tool. There is.

Japanese Unexamined Patent Publication No. 2015-213972 JP-A-2015-213992

Introduction to cutting of difficult-to-cut materials, Norihiko Narutaki, Journal of Precision Engineering 58 (12), 1949-1952, 1992

However, Patent Document 1 proposes that coolant is supplied between the cutting tool and the chips from the passage (local space) of the (tip) breaker provided separately from the cutting tool to suppress the pressure drop of the coolant. It's just that. That is, Patent Document 1 does not relate to the cutting tool (cutting tool) itself.

Patent Document 2 describes a cutting tool (restraint tool) that can improve the quality of a cutting product by guiding chips to a taxiway from a restraint surface provided separately from the rake face and preventing the chips from returning to the machining point. is suggesting. However, Patent Document 2 does not make a concrete proposal regarding extending the life of a cutting tool (particularly a flat tool).

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a new cutting tool capable of extending the service life.

As a result of diligent research to solve this problem, the present inventor has achieved a new form in which the amount of heat transferred from high-temperature chips to a cutting tool can be suppressed or the heat dissipation thereof can be promoted, and the temperature rise during cutting can be significantly reduced. I came up with a cutting tool. By embodying and developing this idea, the present invention described below was completed.

"Cutting tools"
(1) The cutting tool of the present invention is a cutting tool including a cutting edge for cutting a work material and a rake face extending rearward from the cutting edge, and further, from at least a part of the rake face to the inside. It has a groove-shaped or hole-shaped penetrating inward path formed toward, and the inward path has an inclined surface extending from a front edge on the rake face side to an inner lower trailing edge penetrating the slope. on the surface, conditions surface consisting of ridges or concave extending from said front edge to said trailing edge is formed.

(2) According to the cutting tool of the present invention, the life of the cutting tool can be extended, and the manufacturing (machining) cost of the cut product can be reduced. The reason for this can be inferred as follows. Chips generated from the work material cut by the cutting edge (also referred to as "tool cutting edge" or simply "cutting edge") come into contact with the rake face (at least the cutting edge side area) extending from the cutting edge to the rear (the direction in which the cutting edge flows out). It flows while doing. Since the chips are extremely hot, the cutting tool that comes into contact with the chips also becomes considerably hot due to heat transfer.

The cutting tool of the present invention is provided with an inward path having an inclined surface extending from the rake face behind the cutting edge to the inside (particularly diagonally rearward), and the inclined surface is provided at least in a region near the front edge side (rake surface side). A strip having a ridge or a recess extending inward (diagonally downward) rearward is formed. Due to the presence of this strip (convex or concave), adhesion between chips and inclined surface is avoided, and coolant (cutting fluid, machining fluid, etc.) is prevented at least near the front edge of the inclined surface (near the trailing edge of the rake face). A flow path for (coolant, etc.) is secured. As a result, the coolant can be stably supplied to the vicinity of the cutting edge where the temperature is most likely to be high.

As a result, for example, even when the cutting thickness of the work material (that is, the thickness of chips) is relatively large and the conventional cutting tool does not sufficiently supply the coolant to the vicinity of the cutting edge, the present invention According to the cutting tool, the coolant can be sufficiently supplied to the vicinity of the cutting edge. Therefore, the cutting tool of the present invention can significantly reduce the temperature rise of the cutting tool when cutting is performed in a wet environment to which coolant is supplied.

In addition, the rake face from the cutting edge to the front edge of the sloping surface (referred to as the "tip rake face") corresponds to the shape of the sloping surface (convex or concave) near the front edge of the sloping surface. Also, convex portions and concave portions are formed. Therefore, the tip rake face according to the present invention has a smaller contact area with chips than the conventional rake face having no unevenness. As a result, in the cutting tool of the present invention, the amount of heat input from the chips and the amount of heat generated by friction with the chips are further suppressed.

Further, since the trailing edge side of the tip rake face has an uneven shape, not only the contact area with the chips can be reduced, but also the outflow direction of the chips can be controlled. When the cut thickness of the work material is small, the chips flow out along the rake face, but when the cut thickness is large, the chips tend to flow out below the rake surface. In particular, when the chips become thick as described in Patent Document 2, the chips tend to flow into the inward path. However, in the case of the present invention, even if the cutting thickness is large, the chips are supported by the convex portion of the tip rake face that is relatively long in the outflow direction (or the direction substantially orthogonal to the cutting edge ridge line). Therefore, even if the cutting thickness is longer than the length of the recess on the tip rake face, the chips tend to flow out in the direction along the rake face rather than the inward path. Therefore, in the cutting tool of the present invention, contact with high-temperature chips is further suppressed, and temperature rise and thermal wear can be reduced.

Even if the cutting thickness is large and the chips may flow from the rake face at the tip along the inclined surface of the inward path, the cutting tool of the present invention still suppresses contact with the high-temperature chips. Will be done. In such a case, the chips come into contact with only the ridges on the inclined surface and easily flow. Therefore, even on the inclined surface of the cutting tool, heat transfer, friction, wear, etc. generated between the cutting tool and the high-temperature chips are suppressed. Such an action effect of the present invention also applies to the case where the cutting process is performed in a dry environment where the coolant is not supplied or is small. Therefore, the cutting tool of the present invention may be used not only for cutting in a wet environment but also for cutting in a dry environment.

<< Processing method >>
The present invention can be grasped not only as a cutting tool described above, but also as a machining method characterized by cutting a work material using the cutting tool described above. Such a machining method is effective for various machining in which a cutting tool and chips come into contact with each other. For example, the machining method of the present invention may be continuous machining such that one cutting tool is in continuous contact with a work material or chips, such as turning. Further, the processing method of the present invention may be intermittent processing such as milling, in which one cutting tool and a work material or chips are in intermittent contact with each other. Further, as described above, the processing method of the present invention may be performed in a wet environment or a dry environment. The machining method can also be grasped as a manufacturing method of a cut product obtained by cutting a work material with a cutting tool.

《Others》
(1) In the present specification, for convenience of explanation, the upstream side is referred to as "front" (front side, front, etc.) along the outflow direction of chips near the cutting edge (or a direction substantially perpendicular to the cutting edge ridge line), and downstream. The side is called "rear" (rear side, rear, etc.). Also, for convenience, the direction from the rake face toward the inside of the cutting tool (or the direction in which the rake angle increases with the rake face as the boundary) is downward, and the opposite direction (or the direction in which the rake angle decreases with the rake face as the boundary) is upward. Also called.

(2) Unless otherwise specified, "x to y" in the present specification includes a lower limit value x and an upper limit value y. A range such as "ab" may be newly established with any numerical value included in the various numerical values or numerical ranges described in the present specification as a new lower limit value or upper limit value.

As an example of the cutting tool of the present invention, it is a schematic diagram which shows when the cutting edge is a straight line. It is a schematic diagram which shows the state of cutting a work material in a wet environment where coolant is supplied using the cutting tool of FIG. It is a schematic diagram which shows various forms concerning the strip surface portion of the tip rake face and the inclined surface. As another example of the cutting tool of the present invention, it is a schematic diagram which shows when the cutting edge includes a curve. It is a model figure of the cutting tool used for the simulation of the cutting edge temperature. It is the photograph which partially enlarged the tip rake face and the sloping surface part of the inclined surface of the cutting tool used in an Example. It is a photograph which shows the state of turning carbon steel using the cutting tool of this invention. It is a photograph which shows the state of turning titanium by using the cutting tool of this invention.

The contents described in the present specification may apply not only to the cutting tool of the present invention but also to a processing method (manufacturing method) using the cutting tool. One or more components arbitrarily selected from the present specification may be added to the above-described components of the present invention. In certain cases (when it is impossible or impractical to directly identify the "object" due to its structure or characteristics (impossible / impractical circumstances), etc.), the components related to the method are It can also be a component of "things" as a product-by-process. Whether or not which embodiment is the best depends on the target, required performance, and the like.

《Introvert》
The inward path according to the present invention is a groove-shaped or hole-shaped passage formed inward from the trailing edge of the rake face (tip rake face) near the cutting edge. The inward path may or may not penetrate the cutting tool. It is preferable that the inward passage is a coolant supply passage (oil passage) that penetrates.

《Inclined surface / convex / concave / striped surface》
The introvert has an inclined surface that extends from its front edge (the trailing edge of the tip rake face) to the inside rear (obliquely downward). The inclined surface may be flat or curved (curved). At least on the front edge side of this inclined surface, there is a striped surface portion composed of ridges (or mountain streaks) or concave streaks (or valley streaks) extending from the front edge to the inner rear (diagonally downward). Due to the presence of this striped surface, the contact area between the chip and the tip rake face or inclined surface can be reduced, friction can be reduced, etc., and even if the cut thickness is large, coolant can be reliably supplied to the cutting edge side, which is the machining point. obtain. There may be various shapes and combinations of ridges and ridges, but usually they are in pairs. However, when only one is formed, for example, only a groove (recess) may be formed along the inclined surface.

Various forms can be considered for such convex and concave stripes, or the striped surface portion in which they are aggregated. For example, the ridges or recesses may be round with a smoothly curved top or bottom, or square with a top or bottom at a predetermined angle. The number of ridges or dents may be singular, but it is usually preferable to have a plurality of ridges or dents. When the strip surface portion is formed by a plurality of ridges or dents, each ridge or dent may have the same shape or a different shape. Also, their arrangement may be regular or irregular. As a typical example, it is preferable that the striped surface portion is a wave surface portion in which a plurality of convex or concave stripes are regularly (particularly periodic) arranged. Further, it is more preferable that the convex and concave stripes have a symmetrical shape.

"Cutting tools"
(1) A cutting tool 1 which is one embodiment of the present invention is shown in FIG. The cutting tool 1 is a tip (flat tool) having a substantially triangular plate shape for turning. Like the conventional insert, the cutting tool 1 has a cutting edge 11, a rake face 12, and a flank surface 13, but also has an inward path 14 with an inclined surface 15 which is not found in the conventional insert.

Between the cutting edge 11 and the front end of the inward path 14, there is a tip rake face 121 that is a part of the rake face 12. The inward path 14 has an open groove shape extending rearward from the rear (end) edge of the tip rake face 121. The front wall of the inward road 14 is an inclined surface 15 extending diagonally downward from the trailing edge of the tip rake face 121. The surface of the inclined surface 15 is a wave surface portion 150 (strip surface portion) in which a plurality of ridges 151 and dents 152 extending diagonally downward from the front end edge (rear end edge of the tip rake face 121) are arranged at equal pitch intervals. It has become.

The ridge 151 is a mountain line having a semicircular cross section, and the concave line 152 is a valley line having a semicircular cross section. The cross-sectional shapes of each are symmetrical, and the transition regions of the adjacent ridges 151 and 152 are smoothly connected by a plane or a curved surface (a straight line or a curved line in the cross section).

(2) FIG. 2 shows how the work material w is cut by using the cutting tool 1 in a wet environment where coolant is supplied. The chips d generated when the work material w is cut by the cutting edge 11 flows out from the cutting edge 11 while adhering to the tip rake face 121. Further, the coolant c supplied from below the inclined surface 15 flows along the recess 152 of the wave surface portion 150 and is supplied to the tip rake face 121 without being shielded by the chips d.

The trailing edge of the tip rake face 121 also has a wave shape including a convex portion 1211 and a concave portion 1212, corresponding to the shape of the wave surface portion 150. Since the recess 1212 bites into the cutting edge 11 side that requires the most cooling during processing, the vicinity of the cutting edge 11 is surely cooled by the coolant c flowing from the recess 152 through the recess 1212.

The contact length of the chip d is different between the convex portion 1211 and the concave portion 1212. By adjusting these contact lengths, it is possible to ensure cooling by the coolant c. For example, if the convex portion 1211 is lengthened, the chips d can flow backward along the rake face 12 while ensuring cooling by the coolant c even when the cut thickness is increased.

(3) In addition to the above, the striped surface portion of the cutting tool may have a form as shown in FIG. 3, for example. FIG. 3 (1) shows a striped surface portion in which convex strips 21 and concave strips 22 having a substantially trapezoidal cross section and symmetrical are arranged at equal pitches. FIG. 3 (2) shows a striped surface portion in which convex strips 31 and concave strips 32 having a substantially triangular cross section and symmetrical are arranged at equal pitches. FIG. 3 (3) shows a strip 41 in which a convex strip 41 having a substantially trapezoidal (or substantially rectangular) cross section and a concave strip 42 having a substantially semicircular cross section are arranged at equal pitches. FIG. 3 (4) shows a strip portion in which a convex strip 51 having a substantially semicircular cross section and a concave strip 52 having a substantially trapezoidal (or substantially rectangular) cross section are arranged at equal pitches. For convenience, the parts other than the ridges and ridges are designated by the above-mentioned reference numerals, and their description is omitted.

(4) The cutting tool of the present invention is not limited to a cutting tool having a cutting edge extending in a straight line, and may have a cutting edge extending in a curved or bent shape. Further, it is preferable that the inward path, the inclined surface or the striped surface portion also has an appropriate form corresponding to the cutting edge. As an example of this, FIG. 4 shows a cutting tool 8 which is another embodiment of the present invention. The cutting tool 8 also has a tip having a substantially triangular plate shape, and the tip rake face 821 thereof has a substantially bent (V sentence) shape along the corner-shaped cutting edge 81. Corresponding to the tip rake face 821, the introvert road 84 has a culvert shape having a substantially triangular (V-shaped) cross section. Further, the inclined surface 85 forming the side surface of the inward path 84 extends diagonally downward (downward from the center of the tip) in a mortar shape from the trailing edge of the tip rake face 821. On the surface of the inclined surface 85, a wave surface portion 850 (strip surface portion) in which a plurality of ridges 851 and dents 852 extending diagonally downward from the front end edge (rear end edge of the tip rake face 821) are arranged at equal pitch intervals. It has become.

《Others》
(1) Various types of cutting tools can be considered depending on the processing form (turning, milling, etc.). For example, the cutting tool of the present invention may be a tip only, or may include a holder and a shank. The work material may be an iron-based material (stainless steel or the like) or an active metal material (aluminum-based, titanium-based, magnesium material, copper-based material, etc.). The form may be rod-shaped, block-shaped, tubular, or the like. The cutting tool of the present invention is preferably used in a wet environment to which coolant is supplied, but may be used in a dry environment to which no coolant is supplied. The coolant referred to in the present specification includes not only a mere coolant but also a cutting oil (processing oil). The supply method thereof may be any of flowing water, shower, mist and the like. Further, the cooling medium (coolant) is not limited to a liquid, and may be a gas such as air or a specific gas (inert gas or the like).

The following analysis and experiments were conducted on cutting tools with linear cutting edges. The present invention will be described more specifically based on this result.

"analysis"
(1) In order to evaluate the influence of an inward road having an inclined surface having a striped surface, a model of cutting tool 1 (example) and cutting tool C1 (comparative example) as shown in FIG. 5 is created and FEM analysis is performed. The temperature at the center of the cutting edge (simply referred to as "cutting edge temperature") was simulated.

The general shape of the cutting tool 1 is the same as that shown in FIG. 1 or 2, but the detailed shape thereof is as shown in FIG. Specifically, the convex strip 151 (convex portion 1211) and the concave strip 152 (recessed portion 1212) constituting the strip surface portion 150 each have a semicircular shape having a symmetrical cross section. The dimensions of each part are as follows. The inner width of the concave portion (concave) was defined (measured) at the central position between the deepest position of the concave portion (concave) and the maximum position of the convex portion (concave).
Inner width of inward path 14 (length parallel to the ridgeline of the cutting edge) L ₀ : 2.8 mm,
Tilt angle of inclined surface 15 (angle from rake surface) θ: 45 °,
Convex length (length from cutting edge to front edge of ridge) L _l : 0.35 mm,
Recess length (length from cutting edge to front edge of recess) L ₂ : 0.1 mm,
Inner width of recess (concave) L ₃ : 0.2 mm,
Pitch P: 0.4 mm

The simulation was performed using analysis software (Abaqus 6.12 / manufactured by Dassault Systemes). At this time, it was assumed that the heat input (Qin) during processing was introduced from the heat input range (rake surface near the processing point) shown in FIG. Specifically, in the cutting tool 1, the tip rake face 121 is set as the heat input range (length in the cutting edge ridge line direction: 2 mm), and in the cutting tool C1, the specific range on the cutting edge side on the flat rake face (2 mm × 0). .7 mm) was set as the heat input range.

The analysis parameters used in the simulation are as follows.
Heat input Q _in : 35 [MW]
Thermal conductivity K: 42 [W / K ・ m]
Specific heat C: 300 [J / kg ・ K]
Density D: 11.7 [kg / m ³ ]
Heat transfer coefficient between tool and holder ht: 5000 [W / K ・ m ² ]
Atmospheric temperature T ₀ : 26 [° C]
Holder temperature Tt: 26 [° C]

The simulation was performed both when cutting without supplying coolant (in a dry environment) and when cutting while supplying coolant (in a wet environment). At this time, the heat transfer coefficient between the surroundings and the cutting tool in a dry environment is h ₀ : 13 [W / K ・ m ² ], and the heat transfer coefficient between the surroundings and the cutting tool in a wet environment is h ₀ : 10000 [W / K ・ m ² ].

(2) By the above simulation, the cutting edge temperature was obtained as follows.
In a dry environment → Cutting tool 1: 606.1 ° C (Example)
Cutting tool C1: 905.9 ° C (Comparative example)
In a wet environment → Cutting tool 1: 394.1 ° C (Example)
Cutting tool C1: 661.3 ° C (Comparative example)

From these results, it is clear that the cutting tool of the present invention can significantly reduce the cutting edge temperature in both a dry environment and a wet environment, and thus prolong the life of the cutting tool. became.

《Experiment》
Using the cutting tool 1 (L _l : 0.35 mm, L ₂ : 0.1 mm, P: 0.4 mm) shown in FIG. 6, a work material made of carbon steel and a work material made of titanium are turned, respectively. The state of (two-dimensional cutting) is shown in FIGS. 7A and 7B (both are simply referred to as "FIG. 7"), respectively. In each case, the cutting thickness t: 0.17 mm.

As can be seen from FIG. 7, the recess length L ₂ is smaller than the cut thickness t, but the convex portion length L ₁ is larger than the cut thickness t. Therefore, the chips were supported by the convex portions, and while maintaining their shape due to the rigidity of the chips, they flowed out in a direction substantially parallel to the rake face without contacting the inclined surface.

<< Summary >>
Based on the above-mentioned contents, the pitch (P) of the ridges or dents according to the present invention is preferably 0.3 to 1 mm and further preferably 0.4 to 0.7 mm. The inner width (L ₃ ) of the recess is preferably 0.15 to 0.6 mm, more preferably 0.2 to 0.4 mm. The tip rake face, which is a part of the rake face and is located between the cutting edge and the front edge of the inclined surface, has a length from the cutting edge to the front edge of the ridge (convex length L ₁ ) of 0.25 to 0. It is preferably 0.5 mm and more preferably 0.3 to 0.4 mm. The tip rake face, which consists of a part of the rake face and is located between the cutting edge and the front edge of the inclined surface, has a length from the cutting edge to the front edge of the recess (recess length L ₂ ) of 0.05 to 0. It is preferably 0.3 mm and even 0.1 to 0.2 mm. The angle (tilt angle: θ) of the inclined surface with respect to the rake face is preferably 10 to 90 °, more preferably 30 to 60 °.

1 Cutting tool 11 Cutting edge (tool cutting edge)
12 Scoop surface 121 Tip scoop surface 14 Inward road 15 Inclined surface 150 Striped surface 151 Convex strip 152 Concave strip

Claims (8)

A cutting edge that cuts the work material and
The rake face that runs backward from the cutting edge,
It is a cutting tool equipped with
Further, a groove-shaped or hole-shaped penetrating inward path formed inward from at least a part of the rake face is provided.
Inner Mukoro has an inclined surface continuous to the trailing edge of the inner lower penetrating from the front edge in the rake face side,
The inclined surface, a cutting tool conditions surface consisting of ridges or concave extending from said front edge to said trailing edge is formed. The cutting tool according to claim 1, wherein the striped surface portion is a wavy surface portion in which a plurality of the convex strips or the concave strips are regularly arranged. The cutting tool according to claim 2, wherein the ridge or the dent has a pitch of 0.3 to 1 mm. The cutting tool according to claim 2 or 3, wherein the inner width of the recess is 0.15 to 0.6 mm. The tip rake face, which is composed of a part of the rake face and is located between the cutting edge and the front edge of the inclined surface, has a length from the cutting edge to the front edge of the ridge of 0.25 to 0.5 mm. The cutting tool according to any one of claims 1 to 4. The tip rake face, which is composed of a part of the rake face and is located between the cutting edge and the front edge of the inclined surface, has a length from the cutting edge to the front edge of the recess of 0.05 to 0.3 mm. The cutting tool according to any one of claims 1 to 5. The cutting tool according to any one of claims 1 to 6, which has an integral structure. The cutting tool according to any one of claims 1 to 7, which is for turning.