JPH11300517A - Cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the service life of an end mill having an end face edge and a side surface edge to be used in the cutting such as drilling and boring, to improve the machining efficiency, and to reduce the control cost of tools. SOLUTION: The function (f) with the wear S of a flank of an end face edge as the dependent variable and the end face edge cutting volume U of a work to be cut by the end face edge as the independent variable, and the function (g) having the wear T of the flank of a side surface edge as the dependent variable and the side surface edge cutting volume V as the independent variable are obtained through measurement, the volume ratio R of the end face edge cutting volume U to the side surface edge cutting volume V of the target work to be cut under an approximately same condition as the work is determined using the end surface edge wear limit SLIM which is the limit value on the cutting performance of the wear S of the flank of the end face edge, the side surface edge wear limit TLIM, the inverse function f<1> of the function (f), and the inverse function g<-1> of the function (g), and the machining route of an end mill to satisfy the volume ratio R is selected as the machining route of the target work. The function f, g may have arbitrary machining conditions as other independent variables.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting method for drilling, boring, grooving or shaping a workpiece by using an end mill having an end face and a side face.

[0002]

2. Description of the Related Art For example, when a hole having a diameter larger than a tool diameter is drilled in a workpiece, a method has previously been adopted in which a hole is drilled and then the hole is expanded using an end mill. However, recently, from the viewpoint of improving the processing efficiency (reducing the tool change time) and reducing the tool management cost, the method of performing the cutting using one end mill is becoming mainstream. The end mill has two types of cutting blades, an end surface blade and a side surface blade, and cutting can be performed using both of them. FIG. 7 is a cross-sectional view of a workpiece 101 showing a cutting method according to the related art. FIG. 7A shows a positional relationship between the end mill and the workpiece 101 at the time of cutting by the end face blade, and FIG. 7B shows a position of the end mill and the workpiece 101 at the time of cutting by the side face blade. Shows the relationship. As described above, when cutting is performed using one end mill, a method is used in which after the end mill is used to make a hole, the hole is expanded using the side mill of the end mill. Since normal processing cannot be performed when the wear of the end face blades or the side face blades proceeds, if at least one of the end face blades or the side face blades is worn by a certain amount, re-polishing is performed to regenerate a new cutting edge. There is also a limit to the number of times of re-polishing or the amount of polishing, and when it reaches a certain limit, the life of the tool itself is reached at that point.

[0003]

[0005] In actual cutting, machining conditions are various, and an end face blade having a large wear limit value (end face wear limit value S _LIM > side face wear limit value T _LIM ) has a longer life. Not always long. Depending on the processing conditions, the wear of the end face blade proceeds faster than that of the side face blade, and even though the end face blade has a larger wear limit value, the end face blade may reach the wear limit first. As described above, when the wear of one of the cutting blades progresses faster than the other, the processing of the tool can be performed in a state where the processing of one of the cutting blades can still be performed but the processing of the other cutting blade can no longer be performed. It will end its life. In other words, the cutting volume that can be cut with one end mill (end face cutting volume U + side cutting volume V) is reduced, or if the other cutting blade that can still process is used up, the cutting volume is reduced. In this case, the number of times of tool change increases, and in any case, the machining efficiency decreases and the tool management cost increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to use an end mill having end blades and side blades to drill, bore, and bore a workpiece.
An object of the present invention is to increase the cutting volume per one end mill in a cutting process for performing grooving or shaping, thereby prolonging the life of the end mill and reducing tool management costs.

[0005]

In order to solve the above-mentioned problems, the following means are effective. That is, the first means uses an end mill having an end blade and a side blade,
In a cutting method for drilling, boring, grooving or shaping a workpiece, a wear amount S of a flank of an end face blade and a value U related to an end face blade cutting volume of a workpiece cut by the end face blade.
Is obtained by measurement, and a correspondence g between the amount of wear T of the flank of the flank of the side blade and the side blade cutting volume related value V of the workpiece cut by the side blade is obtained by measurement. , The edge blade wear limit value S _LIM which is a limit value on the cutting performance of the flank wear amount S of the edge blade, and the side blade wear limit which is the limit value of the flank wear amount T of the side blade on the cutting performance. Value T
_{Using the LIM} , the correspondence f, and the correspondence g, the end-face cutting volume-related value U with respect to the side-face cutting volume-related value V of the target workpiece cut under substantially the same conditions as the workpiece. The purpose is to determine the volume-related value ratio R and select the machining path of the end mill that satisfies the volume-related value ratio R as the machining path for cutting the target workpiece.

The second means is the same as the first means, wherein the value related to the cutting volume of the end face is defined as the cutting volume of the end face of the workpiece cut by the end face, and the value V related to the cutting volume of the side face. The relationship f is a function having the wear amount S as a dependent variable, the edge face cutting volume U is a function having an independent variable, and the correspondence g is a wear amount T. A function having the side surface cutting volume V as an independent variable, an end surface blade wear limit value S _LIM , a side blade wear limit value T _LIM , an inverse function f ^{−1 of the} function f, and an inverse function of the function g. Using g ⁻¹ , the volume ratio of the edge blade cutting volume U to the side edge cutting volume V of the target workpiece cut under substantially the same conditions as the workpiece is determined. It is used as the volume-related value ratio R.

Further, the third means is the same as the second means, except that the function f and the function g are changed in addition to the end face cutting volume U or the side cutting volume V, the tool type variable K of the end mill, the end mill cutting volume. Cutting speed variable v at the time of machining, feed amount variable F per end mill edge, end mill axial depth variable Ad, end mill radial depth variable Rd, end mill pick feed variable Pf, end mill regrind N Or a function having the workpiece material variable W as another independent variable. The above-mentioned means can solve the above-mentioned problems.

[0008]

FIG. 1 is a graph showing the relationship between the cutting volume of a workpiece and the amount of wear on the flank of an end mill. The vertical axis of this graph is the flank wear S of the end face blade and the flank wear T of the side face flank, and the horizontal axis is the end face cutting volume U of the workpiece cut by the end face blade and the side edge. Is the side blade cutting volume V of the workpiece to be cut. Further, S _LIM is a limit value on the cutting performance of the amount of wear S of the flank of the end face blade (end face blade wear limit value), and T _LIM is a value on the cutting performance of the amount of wear T of the flank face of the side face blade. It is a limit value (side blade wear limit value). As can be seen from the graph of FIG.
In general, the amount of wear S is a monotonically increasing function of the cutting volume U of the end face, and if the function S = f (U) can be obtained by measurement, the end face can be cut before the next end mill regrind. The maximum value U _MAX of the end face cutting volume that can be obtained can also be obtained by the following equation.

U _MAX = f ^-1 (S _LIM ) (1) Similarly, the maximum value V _MAX of the side blade cutting volume that the side blade can cut before the next end mill regrind is given by the following equation. You can ask.

V _MAX = g ^-1 (T _LIM ) (2) Accordingly, the life of the end mill is prolonged by increasing the cutting volume per one end mill (the cutting volume U of the end face + the cutting volume V of the side edge). The most effective method is to reduce the work volume of the workpiece per end mill by (U _MAX + V
_MAX ). That is, it suffices that the life of the edge blade and the life of the side blade can be almost simultaneously reached. Therefore, if the volume ratio of the edge cutting volume U to the side cutting volume V of the target workpiece can be maintained at the value of R shown in the following equation, the life of the end mill can be maximized.

R = U _MAX / V _MAX = f ⁻¹ (S _LIM ) / g ⁻¹ (T _LIM ) (3)

The function f and the function g are, in addition to the end face cutting volume U or the side cutting volume V, a tool type variable K of the end mill, a cutting speed variable v, a feed amount variable F per tooth, an axial direction. The cut amount variable Ad, the radial cut amount variable Rd, the pick feed variable Pf, the number of re-polishing N, or the workpiece material variable W may be another independent variable. By assigning these variables relating to the processing conditions to the independent variables of the function f and the function g, it is not necessary to perform the measurement for obtaining the functions f and g each time the processing conditions change, thereby improving the working efficiency. .

In addition, instead of the end face cutting volume U, the cutting time t _S of the workpiece by the end face blade is used as the end face cutting volume related value, and instead of the side face cutting volume V, the side blade cutting volume related value is used. Alternatively, the machining path of the target workpiece may be selected so as to satisfy the ratio t _S / t _T using the cutting time t _T of the workpiece by the side blade. Thereby, the cutting time of the target workpiece by the end blade and the cutting time of the target workpiece by the side blade can be determined such that the life of the end blade and the life of the side blade are almost simultaneously reached. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. (First Embodiment) FIG. 2 shows a plan view (a) and a sectional view (b) of a workpiece 100 to be cut in this embodiment. Workpiece 100, longitudinal L, transverse L, a metal plate having a thickness D, is penetrated by one of the end mill a hole radius r ₂ in the center. In this case, first, the radius r ₁ and the cutting volume U (= π) are set at the center of the workpiece 100 by the method shown in FIG.
The dr ₁ ²⁾ holes in the passed through with the end face edge of the end mill,
Subsequent methods to indicated Figure 7 (b), finished in a hole of radius r _2. By this method, when drilling holes with a radius r ₂ to the number of workpiece 100 isomorphic, depending on the value of the ratio of the radius r ₁ to the radius _{r 2 γ (≡r 1 / r} 2), the end face of the end mill It is determined which of the blade or the side blade will end its life first. The volume of the portion to be cut by the side edges of the workpiece 100, i.e. a side edge cutting volume V is, πDr _{² 2} (1-
γ ² ), the value of γ that can maximize the life of the end mill is given by the following equation.

U / V = γ ² / (1−γ ² ) = R (4)

Γ = (R / (1 + R)) ^1/2 (5) where R is the volume ratio R determined by (3).
That is. If the machining path at the time of cutting is determined by such a method, the life of the end mill can be maximized.

FIG. 3 is a flowchart for realizing the first embodiment of the present invention. First, in step 300, a wear test is performed. That is, under substantially the same conditions as the target cutting, the amount of wear S of the flank of the end face with respect to the cutting volume U of the end face of the workpiece cut by the end face of the end mill, and the work cut by the side edge. The wear amount T of the flank of the side blade of the end mill with respect to the side blade cutting volume V of the object is measured. Next, in step 320, the above cutting volume U
And the wear amount S, and the relationship between the cutting volume V and the wear amount T are examined. That is, the function S = f (U) and the function T = g
(V) is obtained. In step 340, the volume ratio R of the end face edge cutting volume U to the side edge edge cutting volume V of the target workpiece is determined by equation (3). In step 360, a machining path of the end mill that satisfies the volume ratio R is determined as determined from FIG. 2 and equation (5). Finally, step 380
Then, according to the machining path of the end mill determined in step 360, the target workpiece 100 is cut.
When the above method is used, the effect of the present invention can be obtained by the operation of the present invention.

(Second Embodiment) In the first embodiment, a method of measuring the functions f and g each time the machining conditions change is adopted. However, all the expected cutting conditions are determined in advance. Collectively, the function S = f ₁ (U, K, v, F,
Ad, Rd, Pf, N, W) and the function T = g ₁ (V,
If K, v, F, Ad, Rd, Pf, N, W) are determined, the productivity during the subsequent cutting can be improved. In this embodiment, such a method will be described. Here, K is a tool type variable of the end mill,
v is a cutting speed variable, F is a feed amount variable per tooth, Ad
Is an axial depth variable, Rd is a radial depth variable, Pf is a pick feed variable, N is the number of regrinds, and W is a workpiece material variable. FIG. 4 is a flowchart for obtaining the function f ₁ and the function g ₁ in the second embodiment of the present invention. First, in step 410, all the expected cutting conditions are investigated to determine all the cutting conditions for the full wear test. Next, step 420
Now, the processing conditions for the first measurement in the measurement system are specifically set. In step 430, the amount of wear on the flank is measured. That is, the amount of wear S of the flank of the end face blade with respect to the cutting volume U of the end face of the workpiece cut by the end face of the end mill, and the side edge of the end mill with respect to the cutting volume V of the side edge of the workpiece cut by the side edge Is measured for the amount of wear T on the flank.

In step 440, the relationship between the cutting volume U and the amount of wear S and the relationship between the cutting volume V and the amount of wear T are examined. That is, the function S = f (U) and the function T = g (V)
Ask for. In step 450, it is checked whether or not the measurement has been performed under all the measurement conditions determined in step 410. If all the measurement has been completed, the process proceeds to step 470; otherwise, the process proceeds to step 460. In step 460, the tool type variable K of the end mill, the cutting speed variable v, the feed amount variable F per tooth, the axial depth of cut variable Ad, the radial depth of cut variable Rd, the pick feed variable Pf, the number of regrinds N, or Then, the value of at least one of the material variables W of the workpiece is changed, and the process proceeds to step 430. Finally, in step 470, the function S = f (U) and the function T = g (V) obtained in step 440 are newly calculated as follows:
Function S = f ₁ (U, K, v, F, Ad, Rd, Pf,
N, W) and the function T = g ₁ (V, K, v, F, Ad,
Rd, Pf, N, W).

Next, a method for cutting the workpiece 100 using these functions f ₁ and g ₁ will be described. 5, in the second embodiment of the present invention, shows a flow chart of performing cutting by using a function f ₁ and the function g _1. First, in step 500, processing condition variables (K, v, F, Ad, Rd,
Pf, N, W) are specifically determined. Step 52
0, the function S = f ₁ (U, K, v, F, Ad, Rd,
Pf, N, W) and the function T = g ₁ (V, K, v, F,
Ad, Rd, Pf, N, W) are added to the processing condition variables (K, v, F, Ad, Rd, Pf,
N, W), the function S = f (U)
And the function T = g (V) is specifically determined. In the processing after step 340, the same processing as in the first embodiment is performed. That is, in step 340, the volume ratio R of the end face edge cutting volume U to the side edge edge cutting volume V of the target workpiece is determined by equation (3). In step 360, a machining path of the end mill that satisfies the volume ratio R is determined as determined from FIG. 2 and equation (5). Finally, in step 380,
According to the processing path of the end mill determined in step 360, the target workpiece 100 is cut. When the above method is used, the effect of the present invention can be obtained by the operation of the present invention.

In the second embodiment, step 470 is executed at the end of the flowchart of FIG.
0 may be performed at any time after step 440 and before step 520 in the flowchart of FIG. Until step 520 is completed, there are several methods for obtaining the function S = f (U) and the function T = g (V) under the processing conditions of the target cutting processing, as known prior arts in the field of current numerical analysis. Methods are known, and the invention can be practiced using any of those methods.

(Third Embodiment) FIG. 6 shows another flowchart for performing cutting using the functions f ₁ and g ₁ obtained in the second embodiment. According to this flowchart, even when cutting a plurality of workpieces having different cutting conditions between the end mill polishing and the next polishing, the life of the end face blade and the side face blade of the end mill can be reached at the same time. First, in step 600, variables S, T, and N are initialized. That is, the values of the variables S, T and N are set to 0, respectively.
Next, in step 605, the magnitude relationship between the value of the variable S and the value of the end face edge wear limit value S _LIM and the magnitude relationship between the value of the variable T and the value of the end face edge wear limit value T _LIM are examined. Are smaller, the process proceeds to step 500; otherwise, the process proceeds to step 670. In step 500,
Processing condition variables (K, v, F, A
d, Rd, Pf, N, W) are specifically determined. In step 520, the function S = f ₁ (U, K, v, F, A
d, Rd, Pf, N, W) and the function T = g ₁ (V,
K, v, F, Ad, Rd, Pf, N, W) are added to the processing condition variables (K, v, F, Ad, R) determined in step 500.
d, Pf, N, W), the function S
= F (U) and the function T = g (V). In step 610, the value of the volume ratio R is determined by (6).

R = (f ⁻¹ (S _LIM ) −f ⁻¹ (S)) / (g ⁻¹ (T _LIM ) −g ⁻¹ (T)) (6)

In step 620, the cutting volume U of the end face and the cutting volume V of the side edge of the target workpiece are calculated as (7) and (8).
Ask by Here, u is the total cutting volume (u = U + V) of the target workpiece.

U = R · u / (1 + R) (7)

V = u / (1 + R) (8) In step 630, whether or not the amount of wear of the cutting edge of the end mill reaches the wear limit value during cutting is determined using (9) and (10). If both (9) and (10) hold, the process proceeds to step 640; otherwise, the process proceeds to step 670.

U ≦ f ⁻¹ (S _LIM ) −f ⁻¹ (S) (9)

V ≦ g ⁻¹ (T _LIM ) −g ⁻¹ (T) (10) In step 640, a machining path according to the values of U and V obtained in (7) and (8) is determined. In step 650, cutting is performed along the processing path determined in step 640. In step 660, a process of updating the wear amount of the flank of the cutting edge is performed according to (11) and (12).

[Expression 11] New wear amount S = f (U + f ^-1 (pre-wear amount S)) (11)

(12) New wear amount T = g (V + g ^-1 (pre-wear amount T)) (12)

In step 665, it is checked whether or not the next workpiece exists, and if so, the process proceeds to step 605,
Otherwise, the process is completed. In step 670,
The value of the re-polishing number N is increased by one. Step 675
Then, it is checked whether or not the value of N exceeds the limit value N _{LIM of the} number of times of re-polishing. If it exceeds, the process proceeds to step 690, otherwise to step 680. In step 680, the end mill is polished again. In step 685, the wear amount of the flank of the cutting blade is reset. That is, the variable values of the wear amount S and the wear amount T are reset to 0, respectively, and the process proceeds to step 605. In step 690, the end mill whose life has expired is replaced with a new end mill, and the process proceeds to step 600. By the above method,
Even when cutting a plurality of workpieces having different cutting conditions between the end mill polishing and the next polishing, the life of the end face blade and the side face blade of the end mill can be reached at the same time. Although not mentioned here, the wear limit values S _LIM and T _LIM are generally a function of the tool type variable K of the end mill and the number N of regrinds.

In the above embodiment, a method of forming a cylindrical hole in a metal plate having a thickness D has been described as an example. However, the cut shape of a workpiece can be machined using the end face blade and side face blade of an end mill. Any shape may be used as long as the shape is appropriate. In the above embodiment, the value γ of the ratio of the radius r _{1 to} the radius r ₂
(≡r ₁ / r ₂ ) determines which of the end face edge or side edge of the end mill will end its life first, and has a parameter γ that determines which such edge will end its life first. When the shape to be obtained is cut, the present invention can be applied to any shape. In this case, the equations (4) and (5) for the parameter γ may be changed to an equation that matches the shape.

The function f, the function g, the function f _1, and the function g ₁ do not necessarily need to be represented by mathematical expressions such as polynomials. If these are one-to-one mappings specifically defined by a certain algorithm, operation, or mathematical formula, the present invention can be implemented using the one-to-one mappings.

In the above embodiment, R is the volume ratio of the edge cutting volume U to the side cutting volume V.
This ratio is defined as the cutting time t of the end face to the cutting time t _T of the side face.
The time ratio of _S may be used. In this case, (1),
Instead of (2) and (3), the following (13) and (1)
4) determines the time ratio R _t using (15), it may be performed machining object of workpieces in accordance with the time ratio R _t.

S = p (t _S ) (13)

T = q (t _T ) (14)

R _t = p ^-1 (S _LIM ) / q ^-1 (T _LIM ) (15) where p is the wear amount S of the flank of the end face as a dependent variable, and Is a function having as an independent variable the end face cutting time t _S , which is the time at which the workpiece is cut by
q is a function having the amount of wear T of the flank of the flank of the end face as a dependent variable and the cutting time t _T of the end face as an independent variable, which is the time at which the workpiece is cut by the end face.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a cut volume of a workpiece and a wear amount of a flank of an end mill.

FIG. 2 is a plan view (a) and a cross-sectional view (b) of a workpiece 100 showing a method of obtaining a machining path satisfying a volume ratio R in the first embodiment of the present invention.

FIG. 3 is a flowchart for realizing a first embodiment of the present invention.

FIG. 4 is a flowchart for obtaining a function f and a function g in the second embodiment of the present invention.

FIG. 5 is a flowchart for performing cutting using a function f ₁ and a function g ₁ in a second embodiment of the present invention.

FIG. 6 is a flowchart for performing cutting using a function f ₁ and a function g ₁ in a third embodiment of the present invention.

FIG. 7 shows a workpiece 1 showing a cutting method in the prior art.
FIG.

[Explanation of symbols]

 f: A function having S as a dependent variable and U as an independent variable g ... A function having T as a dependent variable and V as an independent variable R ... Volume ratio of U to V S: Amount of wear of the flank of the end face T ... Amount of wear of flank of flank of side blade U… Cutting volume of end blade V… Cutting volume of side blade W… Workpiece material variable K… Tool type variable

Claims (3)

[Claims] 1. A cutting method for drilling, boring, grooving or shaping a workpiece by using an end mill having an end face blade and a side face edge, wherein the amount of wear of the flank of the flank face of the end face blade is S And a corresponding relationship f between the end face cutting volume related value U of the workpiece cut by the end face blade is obtained by measurement, and the amount of wear T of the flank of the flank of the side face blade and the cutting by the side face blade are performed. The corresponding relationship g between the side surface cutting volume related value V of the workpiece and the cutting edge is determined by measurement, and the end surface blade wear limit value S _LIM which is the limit value in the cutting performance of the flank wear amount S of the end surface blade. The side work wear limit value T _LIM , which is a limit value on the cutting performance of the flank wear amount T of the flank flank, the correspondence f and the correspondence g, and Side blade cutting volume related value V of the target workpiece cut under the same conditions Determining a volume-related value ratio R of the end-face cutting volume-related value U, and selecting a machining path of the end mill that satisfies the volume-related value ratio R as a machining path for cutting the target workpiece. Cutting method. 2. The end face cutting volume related value U is an end face cutting volume of the workpiece cut by the end face blade, and the side blade cutting volume related value V is cut by the side blade. The correspondence f is a function having the wear amount S as a dependent variable and the end face cutting volume U as an independent variable, and the correspondence g is the wear. A function having the quantity T as a dependent variable and the side edge cutting volume V as an independent variable, the end face edge wear limit value S _LIM , the side edge edge wear limit value T _LIM, and an inverse function f of the function f. ^-1 and the inverse function g ^{-1 of the} function g, the volume of the end face cutting volume U with respect to the side cutting volume V of the target workpiece cut under substantially the same conditions as the workpiece. Determining the ratio and using this volume ratio as the volume-related value ratio R Cutting method according to claim 1, wherein. 3. The function f and the function g are, in addition to the end face cutting volume U or the side cutting volume V, a tool type variable K of the end mill, and a cutting speed variable v at the time of cutting of the end mill. The feed amount variable F per tooth of the end mill, the axial cut amount variable Ad of the end mill, the radial cut amount variable Rd of the end mill, the pick feed variable Pf of the end mill, the re-grinding frequency N of the end mill, or 3. The cutting method according to claim 2, wherein the material variable W of the workpiece is another independent variable.