JP4836161B2 - Rotary cutting tool - Google Patents

Description

  The present invention relates to a rotary cutting tool, and more particularly to a rotary cutting tool in which cutting teeth are provided at unequal pitch angles.

As a rotary cutting tool used when cutting and processing a workpiece such as metal, for example, a circular saw in which a plurality of cutting teeth are radially projected on the outer peripheral portion of a circular main body is known. It has been. FIG. 5 is an enlarged view showing a part of a circular saw 10 conventionally used, and each cutting tooth 12 is provided on the outer peripheral edge of the main body at an equal pitch angle θ spaced apart from each other by a fixed interval. Further, a separation distance (cutting radius) R ₀ from the cutting tooth 12 to the rotation center O of the circular saw 10 is constant in any cutting tooth 12.

When cutting using the circular saw 10, as described above, the cutting teeth 12 are arranged at an equal pitch angle θ, so that the relative feed speed (feed) for cutting the work 14 of the circular saw 10 is set. When the speed is constant and the workpiece 14 is cut linearly, each cutting tooth 12 cuts the workpiece 14 at regular intervals. That is, as shown in FIG. 6, the circular saw 10 having the number of teeth Z, the rotational speed N, and the pitch angle θ (average pitch angle 360 ° / Z) moves linearly in the horizontal direction at a constant feed speed F to move the workpiece 14. If the cutting, any cutting teeth T _n is a line drawn from the rotational center O in the horizontal direction from the time was over (hereinafter, referred to as the cutting line L), adjacent to the reverse rotation direction from該切Kezuha T _n by the time the cutting teeth T _{n + 1} to reach on the cutting line L, the amount circular saw 10 is sent to the work 14 (the cutting teeth T _{n + 1} of the depth of cut S _{n + 1)} is either The cutting teeth 12 are also constant. In other words, since the cutting radii of the cutting teeth 12 are equal, the cutting depth is equal to the distance (feed amount) l ₀ that the circular saw 10 moves per tooth. If the speed F is constant, the cutting amount S ₀ per tooth of the cutting tooth 12 in the circular saw 10 is constant and [Equation 1] S ₀ = l ₀ = F / (N · Z)
It is expressed. For reference, when cutting a workpiece using a circular saw (carbide circular saw) in which a cemented carbide chip is bonded to the cutting teeth, generally, the rotational speed N = 50 to 500 rpm, and the feed speed F = 300 to 1500 mm / min, cutting amount per tooth S ₀ = 0.03 to 0.12 mm. Further, in the following description, the circular saw 10 provided with the cutting teeth 12 at an equal pitch angle θ is referred to as a reference circular saw, and the cutting amount S ₀ and the feed amount l ₀ by the circular saw 10 are defined as a reference cutting amount and These will be referred to as reference feed amounts.

  When the workpiece 14 is cut using the circular saw 10 as described above, the interval at which the workpiece 14 is cut becomes periodic. Due to this periodic cutting, the circular saw 10 and the workpiece 14 resonate. Vibration is likely to occur. Then, this vibration causes a reduction in machining quality on the workpiece machining surface, and in an extreme case, the cutting teeth 12 are lost to reduce the circular saw life.

Therefore, a circular saw shown in Patent Document 1 is known as one developed to deal with such a problem. The circular saw 16, as shown in FIG. 7, the varied values of the pitch angle theta _n, the pitch angle theta _{n + 1} of the cutting teeth T _{n + 1} of any cutting teeth T _n, all cutting The cutting radius of the teeth 12 is the same as that of the reference circular saw 10. That is, the depth of cut S _n of any cutting teeth T _n, the [Equation 2] as a function of the pitch angle _{θ n S n = (F /} N) · (θ n / 360 °)
As shown in FIG. 8, the circular saw 16 cuts the workpiece 14 aperiodically. Therefore, the circular saw 16 of Patent Document 1 is capable of suppressing the resonance vibration generated in the conventional circular saw 10 and improving the cutting surface. Incidentally, circular saw 16 of the Patent Document 1, since the cutting radius R ₀ of each cutting tooth 12 are both equal, feed amount l _n of an arbitrary cutting teeth T _n is the depth of cut S _n of該切Kezuha T _n The same. In the following description, the circular saw 16 is referred to as an unequal pitch circular saw.
Japanese Patent Publication No. 60-8163

  However, when the workpiece 14 is cut using the unequal pitch circular saw 16 shown in Patent Document 1, another new problem occurs. As described above, since the cutting amount of each cutting tooth 12 of the unequal pitch circular saw 16 is different, the cutting resistance applied to the cutting tooth 12 having a large cutting amount, that is, the cutting tooth 12 having a large pitch angle, increases. . Therefore, when an excessively strong cutting resistance is applied to the cutting teeth 12 having a large pitch angle, the tip of the cutting teeth 12 may be chipped or broken. In addition, a so-called tip saw in which a tip is fixed as each cutting tooth 12 has a disadvantage that the tip is dropped due to a large cutting resistance. Moreover, the burr | flash of the cutting | disconnection location of the workpiece | work 14 will become large by cutting force increase, or a cut surface will become rough, and the problem that cutting quality will fall also arises.

  Therefore, it is possible to reduce the load applied to the cutting teeth 12 by reducing the feed speed of the unequal pitch circular saw 16, but this reduces the cutting efficiency and increases the machining cost of the workpiece 14. I'm going to stop.

  That is, the present invention was developed in view of the above-mentioned drawbacks inherent in the rotary cutting tool according to the prior art, and suppresses resonance vibration during cutting and avoids chipping and breakage of cutting teeth. An object of the present invention is to provide a rotary cutting tool that can be used and that does not reduce the processing efficiency.

In order to overcome the above-mentioned problems and achieve the intended purpose, the rotary cutting tool according to the present invention includes:
In a rotary cutting tool in which cutting teeth protrude radially at an irregular pitch angle on the outer peripheral portion of the circular main body and the number of teeth is Z,
An average pitch angle of 360 ° / Z is θ,
An arbitrary cutting tooth is defined as a reference cutting tooth T ₀ ,
The cutting radius of the reference cutting tooth T ₀ is a reference cutting radius R ₀ ,
The cutting teeth positioned on the n-th counter-rotation direction from the reference cutting teeth T ₀ and T _n,
The center angle formed by the reference cutting tooth T ₀ and the cutting tooth T _n with respect to the rotation center O is Θ _n ,
When the relative angle difference α _n is defined as α _n = Θ _n −nθ,
The cutting radius R _n of the cutting teeth T _n, the relative if positive value of the angular difference alpha _n decreases with respect to the reference cutting radius R _0, the reference if the value of the relative angular difference alpha _n is negative by increasing against the cutting radius R _0,
When the workpiece is cut linearly at a constant feed rate, the cutting amount for the workpiece in all the cutting teeth is made substantially equal.

  According to the rotary cutting tool according to the present invention, by providing each cutting tooth with an unequal pitch angle, resonance vibration during cutting is prevented, and the cutting amount in all cutting teeth is substantially equal, It is possible to avoid chipping, breaking or dropping of the fixed tip of the cutting tooth without lowering the processing efficiency.

  Next, a preferred embodiment of the rotary cutting tool according to the present invention will be described below with reference to the accompanying drawings. In addition, although the Example shows the case where a circular saw is used as a rotary cutting tool, it is not necessarily limited to this and rotary cutting tools, such as various milling machines, may be sufficient. In the following description, it is assumed that a circular saw cuts a workpiece linearly at a feed rate F and a rotation speed N.

In the circular saw 18 according to the embodiment, as shown in FIG. 1, cutting teeth 12 having a number of teeth of Z are radially arranged at unequal pitch angles on a circular outer peripheral portion of the main body. Further, the separation distance from the tip of each cutting tooth 12 to the rotation center O, that is, the cutting radius, is set so as to be different from each other by increasing or decreasing the reference cutting radius R ₀ of the reference cutting tooth T _{0 as} a reference. . Hereinafter, a method for setting the cutting radius will be described.

First, as shown in FIG. 2A, description will be made assuming a reference circular saw 10 having a reference cutting radius R ₀ , the number of teeth Z (= 6), and a cutting tooth T ₀ as a reference cutting tooth. As described above, the cutting amount and the feeding amount of each cutting tooth 12 of the reference circular saw 10 are constant and S ₀ = l ₀ (see Equation 1).

Further, as shown in FIG. 2B, an unequal pitch circular saw 16 having a reference cutting radius R ₀ and the number of teeth Z (= 6) and a cutting tooth T ₀ as a reference cutting tooth is assumed. The unequal pitch circular saw 16, as described above, the depth of cut S _n at an arbitrary cutting teeth T _n equal to the feed amount l _n, is expressed by a function of the pitch angle theta _n. Here, Z · θ = 360 °, S ₀ = F / (N · Z) is substituted into Equation 2, and
[Formula 3] S _n = l _n = S ₀ · (θ _n / θ)
It becomes. Here, the cutting radius of each cutting tooth 12 of the unequal pitch circular saw 16 is changed to make the cutting amount in each cutting tooth 12 constant (that is, the cutting amount in each cutting tooth 12 is the reference cutting amount S _0). It is considered that the cutting radius of each cutting tooth 12 is increased or decreased from the reference cutting radius R ₀ ).

The feed amount l ₁ of the cutting tooth T ₁ adjacent in the counter-rotating direction from the reference cutting tooth T ₀ is expressed by the following equation (3):
[Formula 4] l ₁ = l ₀ · (θ ₁ / θ)
It becomes. As shown in FIG. 2 (b), the feed amount l ₁ of the cutting tooth T ₁ of the unequal pitch circular saw 16, so than the reference feeding amount l ₀ l ₀ -l ₁ only small, of該切Kezuha T ₁ By making the cutting radius larger by l ₀ −l ₁ than the reference cutting radius R ₀ , the cutting amount S ₁ of the cutting tooth T ₁ becomes equal to the reference cutting amount S ₀ . Therefore,
[Formula 5] R ₁ = R ₀ + l ₀ −l ₁ = R ₀ + l ₀ · {1− (θ ₁ / θ)}
It becomes. Here, since the reference feed amount l ₀ is equal to the reference cut amount S ₀ ,
[Formula 6] R ₁ = R ₀ + S _0. {1- (θ ₁ / θ)}
It is expressed.

In order for the cutting depth S ₂ of the cutting teeth T ₂ in the unequal pitch circular saw 16 to be equal to the reference cutting depth S ₀ , the position of the initial reference cutting teeth T ₀ on the cutting line L (hereinafter referred to as the origin). O to) from a distance 2S ₀ position apart (i.e.,該切Kezuha T ₂ cutting teeth T ₂ is the position) of cutting of the reference circular saw 10 may be increased or decreased cutting radius R ₂ to the cutting. That is, when the cutting teeth T ₂ arrives onto the cutting line L, since the irregular pitch circular saw 16 is moved by l ₁ + l _2, the cutting radius R ₂ of該切Kezuha T _2, reference If the cutting radius R _{0 is} increased by 2S ₀ − (l ₁ + l ₂ ), the cutting tooth T ₂ cuts at a distance 2S ₀ from the origin O. Therefore,
[Expression 7] R ₂ = R ₀ + 2S ₀ − (l ₁ + l ₂ ) = R ₀ + S _0. {2-((θ ₁ + θ ₂ ) / θ)}
It becomes.

Similarly, when the cutting radii R ₃ , R ₄ ,... Are obtained, the cutting radius R _{n at} any cutting tooth T _n of the unequal pitch circular saw 16 is
[Equation 8] R _n = R ₀ + S _0. {N − ((θ ₁ + θ ₂ +... + Θ _n ) / θ)}
It is expressed. Here, as shown in FIG. 3, θ ₁ + θ ₂ +... + Θ _n is a central angle formed by the reference cutting tooth T ₀ and the cutting tooth T _n with respect to the rotation center O. _{If n} ,
[Formula 9] R _n = R ₀ + S _0. {N− (Θ _n / θ)}
It can be expressed as. Furthermore, as shown in FIG. 3, to define the Θ _n = nθ + _{α n} becomes a relative angular difference alpha _n, it is substituted into Equation 9,
[Formula 10] R _n = R ₀ + S _0. {N− (nθ + α _n ) / θ} = R ₀ − (S ₀ / θ) α _n
It can be expressed as.

Thus, by determining the respective cutting radii in the unequal pitch circular saw 16 by increasing / decreasing with respect to the reference cutting radius R ₀ , the feed amount of each cutting tooth is different as shown in FIG. The respective cutting amounts can be made equal to the reference cutting amount S ₀ . In other words, in the circular saw 18 according to the embodiment, as expressed in Expression 10, the cutting radius of each cutting tooth 12 has the reference cutting radius R ₀ as an intercept and −S ₀ / θ as an inclination. It is defined as a linear function of the relative angle difference α _n . By setting the cutting radius in this way, when the workpiece 14 is cut linearly at a constant feed rate, the depth of cut with respect to the workpiece 14 can be made constant for any cutting tooth. That is, even if the cutting teeth are provided at unequal pitch angles, the respective cutting amounts can be set as the reference cutting amount S ₀ . Therefore, if the work 14 is cut using the circular saw 18 according to the embodiment, the resonance vibration at the time of cutting, which has been a problem in the past, is suppressed, and the tip of the cutting tooth 12 is chipped, broken, or fixed chip. No dropout occurs.

In the embodiment, each cutting radius of the circular saw 18 is determined by increasing or decreasing the cutting radius with respect to the reference cutting radius R ₀ , but the cutting of any cutting tooth T _n-1 is performed. It is also possible to determine the cutting radius R _n of the cutting teeth T _n adjacent in the counter-rotating direction from the radius R _n−1 . That is, when the cutting radius R _n-1 of the cutting tooth T _n-1 is obtained from Equation 8,
[Formula 11] R _n-1 = R ₀ + S _0. {(N-1)-((θ ₁ + θ ₂ +... + Θ _n-1 ) / θ)}
It is expressed. Taking the difference between Equation 8 and Equation 10,
[Formula 12] R _n −R _n−1 = S ₀ · (θ−θ _n ) / θ
It becomes. Thus, the cutting radius R _n at an arbitrary cutting teeth T _n,
[Formula 13] R _n = R _n−1 + S ₀ · (θ−θ _n ) / θ
It can be expressed as. From this equation 13, the cutting radius of each cutting tooth 12 of the circular saw 18 can be determined with reference to the cutting radius of the cutting tooth 12 adjacent in the rotational direction. Of course, even when the circular saw 18 with each cutting radius set according to Equation 13 is used, the cutting amount for the workpiece at each cutting tooth is constant (that is, the reference cutting amount S ₀ ), and the same effect as above. Is obtained.

It is a partial enlarged view of the circular saw which concerns on an Example. It is explanatory drawing showing the mode of cutting of a reference | standard circular saw and an unequal pitch circular saw, (a) shows the reference | standard circular saw and (b) has shown the unequal pitch circular saw. It is explanatory drawing which shows the circular saw which concerns on an Example. It is explanatory drawing which shows the mode of the cutting of the circular saw which concerns on an Example. It is a partially enlarged view showing a reference circular saw. It is explanatory drawing which shows a mode that a reference | standard circular saw cuts. It is a partially expanded view which shows an unequal pitch circular saw. It is explanatory drawing which shows a mode that an unequal pitch circular saw cuts.

Explanation of symbols

12 Cutting teeth 14 Workpiece 18 Circular saw (Rotary cutting tool)

Claims (2)

In the rotary cutting tool (18) in which the cutting teeth (12) protrude radially at unequal pitch angles on the outer peripheral part of the circular main body and the number of teeth is Z,
An average pitch angle of 360 ° / Z is θ,
An arbitrary cutting tooth (12) is defined as a reference cutting tooth T ₀ ,
The cutting radius of the reference cutting tooth T ₀ is a reference cutting radius R ₀ ,
The cutting teeth positioned on the n-th counter-rotation direction from the reference cutting teeth T ₀ and T _n,
The center angle formed by the reference cutting tooth T ₀ and the cutting tooth T _n with respect to the rotation center O is Θ _n ,
When the relative angle difference α _n is defined as α _n = Θ _n −nθ,
The cutting radius R _n of the cutting teeth T _n, the relative if positive value of the angular difference alpha _n decreases with respect to the reference cutting radius R _0, the reference if the value of the relative angular difference alpha _n is negative by increasing against the cutting radius R _0,
A rotary cutting tool characterized in that, when a workpiece (14) is cut linearly at a constant feed rate, the cutting depths of all the cutting teeth (12) with respect to the workpiece (14) are substantially equal. When the rotational speed of the rotary cutting tool (18) is N and the feed rate is F, the average cutting depth S ₀ per tooth is expressed as S ₀ = F / (N · Z) cutting radius R _n of the cutting teeth T _n of the reference cutting a radius R ₀ sectioned, a linear function of the relative angular difference alpha _n to tilt the _{-S 0 / θ R n = R} 0 - (S 0 / The rotary cutting tool according to claim 1, defined as θ) · α _n .

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