JP2020163549A - Cutter and cutting control method - Google Patents

Abstract

To provide a cutter which can secure cutting accuracy without applying a trial and error to a cutting condition at each cutting processing even if a secular change of cutting resistance occurs due to the repetition of the cutting processing, and its cutting control method.SOLUTION: A control part 41 sets target cutting power for setting a deflection amount of a tip part when cutting a cut product by pushing a blade tip part 25 to a tool 21 to a preset target deflection amount. Also, the control part 41 adjusts a set value of a machining allowance so that a peak value of succeeding cutting power reaches target cutting power on the basis of a peak value of the cutting power which is measured everytime the cutting processing is performed, and the target cutting power. The control part 41 controls a push operation at the cutting processing by the tool 21 on the basis of the adjusted set value.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cutting device and a cutting control method thereof.

In a cutting device (lathe) that cuts a work piece by cutting in a direction orthogonal to the direction of the rotation axis while feeding the cantilever-supported tool in the direction of the rotation axis of the work piece, the cantilever-supported tool bends. Is known to affect cutting accuracy. This also applies when a long workpiece is cantilevered and the outer circumference of the workpiece is cut. Therefore, in order to maintain the deflection of the work piece within the permissible range, a technique has been proposed in which the depth of cut (removal allowance) is sequentially adjusted during cutting using a theoretical formula related to the rigidity of the work piece. (See Patent Document 1). It is also conceivable to apply this technique when the side of the tool is cantilevered and adjust the deflection of the tool within an acceptable range.

Japanese Unexamined Patent Publication No. 2006-231420

By the way, by repeatedly performing the cutting process, the tip of the cutting edge of the tool is worn, and a change with time such as a change in cutting resistance occurs. However, the above technique does not take into account changes in cutting resistance over time due to repeated cutting processes. Therefore, after all, there is a problem that the cutting accuracy cannot be ensured unless the cutting conditions such as the depth of cut and the feed amount are set by trial and error for each cutting process.

Therefore, the present invention provides a cutting device and a cutting control method thereof that can ensure cutting accuracy without trial and error of cutting conditions for each cutting process even if the cutting resistance changes with time due to repeated cutting processes. The main purpose is to provide.

In order to solve the above problems, in the first invention,
A cutting edge portion is provided at the tip end portion of the tool protruding from the tool post, the cutting edge portion faces in a direction intersecting the protruding direction of the tool, and the cutting edge portion is pressed against the workpiece to be machined. A cutting device that cuts objects
A target cutting power setting means for setting a target cutting power for setting the bending amount of the tip portion to a preset target bending amount when the tool is pressed against the workpiece for cutting.
Based on the peak value of cutting power measured each time cutting is performed using the tool and the target cutting power, the allowance and the allowance so that the peak value of the next cutting power becomes the target cutting power. An adjustment means to adjust the setting of at least one of the feed amounts, and
A control means for controlling a pressing operation during cutting by the tool based on a set value adjusted by the adjusting means, and a control means.
It is characterized by having.

In the cutting apparatus of the second invention,
The target cutting power setting means has a relational expression (1) “μ = kF” (k is a coefficient) indicating the relationship between the back component force F (N) and the bending amount μ (mm) for the target bending amount. The target back component force obtained by substituting into) is the relational expression (2) “F = α × 60,000 × P / V” (α is) showing the relationship between the back component force F and the cutting power P (KW). It is characterized in that the target cutting power is calculated by substituting the back component force conversion coefficient, V (m / min) into the cutting speed).

In the cutting apparatus of the third invention,
The coefficient k of the relational expression (1) is obtained by applying a force assuming a back component force during cutting to the tip of the tool installed on the tool post and measuring the amount of deflection at that time. It is characterized by that.

In the fourth invention,
A cutting edge portion is provided at the tip portion of the tool protruding from the tool post, the cutting edge portion faces in a direction intersecting the protruding direction of the tool, and the cutting edge portion is pressed against the workpiece to be machined. It is a cutting control method for cutting equipment that cuts objects.
By applying a force assuming a back component force during cutting to the tip portion of the tool installed on the tool post and measuring the amount of deflection of the tip portion at that time, the back component force F (N) is obtained. The relational expression (1) "μ = kF" (k is a coefficient) which shows the relation with the bending amount μ (mm) about the said tool was obtained.
Substituting the preset target deflection amount into the relational expression (1) to obtain the target back component force,
The target back component force is the relational expression (2) “F = α × 60,000 × P / V” (α is the back component force conversion coefficient, which indicates the relationship between the back component force F and the cutting power P (KW). V (m / min) is substituted for cutting speed) to calculate the target cutting power.
Based on the peak value of the cutting power measured each time cutting is performed using the tool and the value of the target cutting power, the peak value of the next cutting power is set to the value of the target cutting power. , Adjust the settings of at least one of the allowance and feed amount,
It is characterized in that the pressing operation at the time of cutting by the tool is controlled based on the adjusted set value.

In the cutting control method of the fifth invention,
The target amount of deflection is set to "1 / N" (N is a natural number of 2 or more) from the allowable tolerance when the cutting process is continuous cutting, and is allowed when the cutting process is intermittent cutting. It is characterized in that it is set to "1 / N" (N is a natural number of 2 or more) from the roundness to be obtained.

According to the first invention, a cutting power having a preset target deflection amount is set as a target cutting power. The cutting power is measured each time cutting is performed using a tool, and based on the peak value and the target cutting power, the allowance and feed amount are set so that the peak value of the next cutting power becomes the target cutting power. It will be adjusted. As a result, even if the cutting resistance changes with time due to repeated cutting, the cutting accuracy can be ensured without trial and error of the cutting conditions of the cutting allowance and the feed amount for each cutting.

According to the second invention, the relational expression (1) showing the relationship between the back component force F and the bending amount μ for the tool and the relational expression (2) showing the relationship between the back component force F and the cutting power P (KW). The target cutting power can be preferably calculated based on the above.

According to the third invention, the coefficient k in the relational expression (1) assumes a back component force F at the time of cutting at the cutting edge of the tool in a state where the tool used for cutting is installed on the tool post. It is obtained by applying a force and measuring the amount of deflection μ at that time. Therefore, the coefficient k in the relational expression (1) is obtained as an eigenvalue of the tool-side part having the tool for which the cutting process is to be executed. Since the deflection of the tool during cutting is also affected by the rigidity of the side that holds the tool, the target cutting power is set in consideration of this. As a result, the cutting accuracy can be further improved.

According to the control method of the fourth invention, similar to the effect obtained by the cutting device in the first invention and the second invention, even if the cutting resistance changes with time due to the repetition of the cutting process, each cutting process is performed. Cutting accuracy can be ensured without trial and error in the cutting conditions of the allowance and feed amount.

In continuous cutting, the tool is constantly bent during cutting, and the bending becomes constant each time the cutting is repeated, which affects the tolerance in the cut portion of the workpiece. Further, in intermittent cutting, the tool swings during cutting, which affects the roundness of the workpiece when it is cut. If the intermittent cutting is repeated, the swing amount of the tool also changes, which affects the roundness. In this regard, according to the fifth invention, in the case of continuous cutting, the target deflection amount is set based on the tolerance, and in the case of intermittent cutting, the target deflection amount is set based on the roundness, so that the tolerance due to the deflection is set. The effect on the roundness and the effect on the roundness due to the swing can be reduced.

The block diagram which shows the control system of a cutting apparatus. Explanatory drawing explaining how the amount of bending about a tool is measured. A graph showing a force-deflection diagram obtained by measuring the amount of deflection. The flowchart which shows the cutting control processing of a cutting apparatus. It is a schematic diagram which shows the state of bending of a tool, (a) shows the case of performing continuous cutting, and (b) shows the case of performing intermittent cutting.

Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings.

As shown in FIG. 1, the cutting device 10 is a lathe device, and includes a tool side unit 11, a work piece side unit 12, and a control controller 13. The tool-side unit 11 holds the tool 21 (bite) and moves the tool 21 for cutting. The work piece side unit 12 holds the work piece W and rotates the work piece W during cutting. The control controller 13 controls the operation of the tool side unit 11 and the workpiece side unit 12. In the present embodiment, the work piece W is assumed to be a cylindrical part formed by casting, and the case where the inner peripheral surface thereof is cut is taken as an example.

The tool side unit 11 has a tool 21 (bite), a tool holder 22, and a tool post 23. The tool 21 includes a long shank 24, and a cutting edge portion 25 (tip) is provided at the tip of the shank 24. The cutting edge portion 25 faces in a direction intersecting the axial direction of the shank 24. The tool holder 22 holds the base end of the tool 21, whereby the tool 21 is cantilevered by the tool holder 22. A tool holder 22 is attached to the tool post 23. The tool post 23 is in contact with a tool post drive unit 26 such as a reciprocating table and a feeding device. The tool post drive unit 26 reciprocates the tool post 23 in the rotation axis direction (Z-axis direction) of the workpiece W, or moves in the cutting direction (X-axis direction) orthogonal to the rotation axis direction. ..

The workpiece side unit 12 includes a spindle 31 and a spindle motor 32. The main shaft 31 has a rotating shaft that is rotatably supported, and a chuck 33 is provided at the tip of the rotating shaft. The work piece W is held by the chuck 33 in a state where its central axis is aligned with the main shaft 31. Therefore, the spindle 31 rotatably holds the workpiece W about its central axis. The rotating shaft of the spindle motor 32 is connected to the rotating shaft of the spindle 31 by a belt 34, and the workpiece W held by the spindle 31 rotates about the central axis by the rotation of the spindle motor 32. .. The cutting edge portion 25 of the tool 21 is pressed against the inner peripheral surface of the rotating workpiece W, whereby the workpiece W is cut.

The control controller 13 has a control unit 41 that controls each operation of the spindle motor 32 and the tool post drive unit 26. The control unit 41 is mainly composed of a well-known microcomputer having a CPU or the like, and has a storage unit 42. The storage unit 42 stores the control program of the cutting device 10. The control unit 41 is connected to the spindle motor 32 and the tool post drive unit 26, respectively, and controls the operation of the spindle motor 32 and the tool post drive unit 26 based on the control program stored in the storage unit 42. That is, the control unit 41 controls the rotation speed by the spindle motor 32 so that the cutting speed V (m / min) of the workpiece W becomes a predetermined set value, or the removal allowance at the time of cutting by the tool 21. The tool post drive unit 26 is controlled so that the (cutting amount) ap (mm) and the feed amount f (mm / rev) in the rotation axis direction become predetermined set values. Numerical values and data used or generated in executing the control program are sequentially stored in the storage unit 42.

Further, the cutting power P (KW) at the time of cutting is sequentially input to the control unit 41. The cutting power data input to the control unit 41 is stored in the storage unit 42. Each time the cutting process for the workpiece W of one product is completed, the control unit 41 uses the cutting power data acquired for the completed cutting process based on the control program to obtain the allowance ap and the feed amount in the next cutting process. The set value of f is calculated and the set value is updated. The control unit 41 controls the operation of the tool post drive unit 26 so that the set value will be updated at the next cutting process.

The storage unit 42 stores a relational expression for the control unit 41 to calculate in order to update the set value. The relational expression is as shown in the following equation (1), and shows the relationship between the back component force F (N) and the bending amount μ (mm) of the tool 21 for the tool 21 installed on the tool post 23.

"Μ = kF" (k is a coefficient) ... (1)
As shown in FIG. 2, the coefficient k of the above equation (1) is the tool 21 installed on the tool post 23 before the first cutting process, that is, in a state where the cutting process has never been performed. It is obtained by measuring the amount of deflection μ. In the measurement work of the amount of deflection μ, a back component force F at the time of cutting is assumed, and a force is applied to the tip portion provided with the cutting edge portion 25 in the cutting direction (direction intersecting the protruding direction of the tool 21). Then, the amount of deflection μ of the tool 21 at that time is measured. The number of measurement points is arbitrary (for example, 5 points as shown in FIG. 3), and a different force F (N) is applied to each measurement point, and the amount of deflection μ (mm) is measured each time. The operator inputs the numerical value of the applied force F and the numerical value of the measured deflection amount μ by using the input unit 43 connected to the control unit 41. When these numerical values are input, the control unit 41 creates a force-deflection diagram shown in FIG. 3, and obtains a coefficient k of the equation (1) based on the force-deflection diagram.

When a tool 21 different from the conventional tool 21 is attached to the tool post 23 and replaced, such as when the tool 21 is replaced with a new one, the coefficient k also changes. Therefore, every time the tool 21 is replaced, the replaced tool 21 is subjected to a measurement work of a bending amount μ with respect to a predetermined force F and a numerical value input work before the first cutting process is performed. Each time a new numerical value of the force F and the amount of deflection μ is input, the control unit 41 obtains the coefficient k, stores it in the storage unit 42, and updates the value of the coefficient k. Therefore, the coefficient k in the equation (1) is obtained as an eigenvalue of the tool side unit 11 having the tool 21 when the tool 21 to execute the cutting process is used.

Next, the cutting control process in the control program of the cutting device 10 will be described with reference to FIG. The cutting control process is executed by the control unit 41.

Here, initial setting values are set in advance for the take-off allowance a and the feed amount f in the cutting process. The initial setting value of the take-off allowance ap is determined by the difference between the workpiece W as the raw material taken out from the mold after casting and the dimensions of the product drawing. Generally, the cutting process goes through two stages of roughing and finishing, or three stages of roughing, intermediate processing and finishing. Therefore, the difference between the workpiece W and the dimensions of the product drawing is divided for each machining stage, and the allowance ap for each machining step is set. Since the accuracy of cutting is not required so much at the stage of roughing and intermediate machining, the cutting control in this embodiment is mainly performed at the time of finishing.

As shown in FIG. 4, in the first step S11, the target back component force Fa (N) is calculated. The equation (1) stored in the storage unit 42 is used to calculate the target back component force Fa. In calculating the target back component force Fa, the target deflection amount (allowable deflection amount) μa (mm) is first set. The target amount of deflection μa is set as “1 / N (N is a natural number of 2 or more)” of the tolerance or roundness of the machined portion in the workpiece W. In this case, "N" is input in advance by the operator using the input unit 43.

In the cantilever-supported tool 21, the cutting edge portion 25 provided at the tip portion thereof bends by receiving a back component force F from the workpiece W during cutting. As shown in FIG. 5A, in the case of continuous cutting in which the inner peripheral surface of the workpiece W is continuously cut, the tool 21 is constantly bent during the cutting process. When such bending of the tool 21 occurs, the accuracy of the cutting allowance a cannot be ensured even if the cutting is made with the set cutting allowance ap, and in the case of continuous cutting, the accuracy of the inner peripheral surface dimension of the workpiece W It becomes a factor that worsens. In FIG. 5A, the bending is emphasized in order to make it easy to understand how the tool 21 bends.

The bending of the tool 21 occurs not only during cutting but also due to repeated cutting. Since the cutting edge portion 25 of the tool 21 receives a back component force F each time the cutting process is performed, the bending gradually becomes constant as the cutting process is repeated. Therefore, the tool 21 is held by the tool post 23 in a bent state even during non-machining. Further, when the cutting process is repeated, the cutting edge portion 25 is worn and the cutting resistance is increased. Therefore, the increase in the cutting resistance also affects the bending amount μ of the tool 21. Therefore, the bending of the tool 21 caused by repeated cutting is a major factor that deteriorates the accuracy of the inner peripheral surface dimension of the workpiece W.

As shown in FIG. 5B, even in the case of intermittent cutting in which the inner peripheral surface of the workpiece W on which the groove Wa is formed is intermittently cut, the tool 21 is bent during cutting of the inner peripheral surface. Further, when the cutting edge portion 25 reaches the groove portion Wa, the bending during the cutting process is eliminated and the tool 21 returns to the original state. In the workpiece W in which a plurality of groove portions Wa are formed, bending and returning to the original state are repeated, and the tool 21 swings. When the tool 21 swings, the accuracy of the cutting allowance a cannot be ensured even if the cutting is made with the set cutting allowance ap, and in the case of intermittent cutting, the roundness of the inner peripheral surface of the workpiece W is affected. To exert. And even in the case of intermittent cutting, as in the case of the above continuous cutting, when the cutting process is repeated, it affects the amount of deflection μ of the tool 21, and eventually the amount of swing of the tool 21, and the accuracy of roundness is improved. It is a major factor that makes it worse. Also in FIG. 5B, the bending is emphasized in order to make it easy to understand how the tool 21 bends.

Therefore, as described above, in the case of continuous cutting, the tolerance is "1 / N (N is a natural number of 2 or more)", and in the case of intermittent cutting, the roundness is "1 / N (N is a natural number of 2 or more)". Is set as the allowable deflection amount (swing amount) μ. The set deflection amount (swing amount) μ is set as the target deflection amount μa, and this is substituted into the equation (1) to calculate the target back component force Fa (N) as shown in FIG. The target back component force Fa is the maximum value of the back component force F in order to keep the deflection amount (swing amount) μ below the upper limit of the allowable deflection amount (swing amount) μ. Indicates whether is preferable. Using the above formula (1) measured in advance with the tool 21 to be used attached to the tool post 23, it is calculated as an eigenvalue of the tool side unit 11 when the tool 21 is used.

In the following step S12, the target cutting power Pa for achieving the target back component Fa is obtained based on the following equation (2) showing the relationship between the back component force F and the cutting power P. F (N) is the back component force, α is the back component force conversion coefficient, P (W) is the cutting power, and V (m / min) is the cutting speed. The cutting back component force conversion coefficient α varies depending on various cutting conditions such as the type of the tool 21, the material and shape of the tool post 23 and the tool holder 22, and a predetermined value is set in advance. Since the cutting speed V and the cutting back component conversion coefficient α are set to predetermined values, the target cutting force Pa can be calculated by substituting the target back component force Fa into the equation (2). Note that step S12 corresponds to the target cutting power setting means.

"F = α x 60,000 x P / V" ... (2)
In the next step S13, the tool post drive unit 26 is controlled based on the preset take-up allowance a and the initial setting value of the feed amount f, and the cutting work is performed on the first work piece W.

In the next step S14, the take-off allowance a and the feed amount f are reset before the next cutting process is performed. Here, it is known that the cutting power P is proportional to the take-off allowance a and the feed amount f from the following equation (3) indicating the required power in the cutting process. Ks (kgf / mm2) is the specific cutting resistance, and η is the mechanical efficiency.

"P = Ks x V x ap x f / 6.120 x η" ... (3)
A peak value is extracted from the data of the cutting power P measured at the time of cutting the first product, and the set values of the take-off allowance a and the feed amount f are adjusted so that the peak value becomes the target cutting power Pa. The measured peak value of the cutting power P is used as the value of the cutting power P to be compared with the target cutting power Pa. This is because the cutting power P and the back component force F are in a proportional relationship according to the above equation (2). Therefore, at the peak value of the cutting power P, the cutting edge portion 25 of the tool 21 receives the largest back component force F. This is because the amount of deflection (amount of swing) μ is the largest.

In general, the cutting power P is often larger than the target cutting power Pa from the time of cutting the first product. Therefore, when adjusting the take-off allowance a and the feed amount f based on the difference between the two differences, the values are adjusted to be small. Note that step S14 corresponds to the adjusting means.

In the case of continuous cutting, it is possible to adjust the set value of at least one of the take-off allowance a and the feed amount f. However, if the feed amount f is adjusted to be small, the time required for the cutting process will be increased accordingly, and the processing efficiency will be lowered. Therefore, in order to maintain the processing efficiency as much as possible, the allowance ap is adjusted in preference to the feed amount f.

In the case of intermittent cutting, the set value of the take-off allowance ap is adjusted. In intermittent cutting, since the swing of the tool 21 affects the roundness, adjusting the feed amount f has almost no effect on the swing of the tool 21. On the other hand, adjusting the take-off allowance a affects the swing of the tool 21, so only the take-off allowance ap is adjusted.

In the following step S15, the tool post drive unit 26 is controlled based on the take-off allowance a and the feed amount f reset in the previous step S14, and the second item is cut. As a result, the cutting power P during the next cutting process is reduced to reduce the deflection and swing of the tool 21, and the range of the deflection and swing of the tool 21 during the cutting process approaches the allowable target deflection amount μa. Be done. As a result, even if the cutting resistance of the cutting edge portion 25 changes with time due to the influence of the rigidity on the tool holding side or the repetition of cutting, the cutting conditions of the allowance a and the feed amount f are not tried and errored for each cutting. , Cutting accuracy can be ensured. Note that step S15 corresponds to the control means.

When the cutting of the second item is completed, it is determined in the next step S16 whether or not the tool 21 has been replaced, and if it has not been replaced yet, the determination is denied and the process returns to the previous step S14. Then, the peak value is extracted from the data of the cutting power P measured at the time of cutting of the second item, and the set values of the take-off allowance a and the feed amount f are adjusted again so that the peak value becomes the target cutting power Pa. And reset. While repeating such control until the tool 21 is replaced, the workpiece W is repeatedly cut.

When the tool 21 is replaced, the determination in step S16 is affirmed, and the control process is temporarily terminated. After the new tool 21 is attached to the tool post 23, the bending amount μ of the tool 21 is measured before the first cutting process, and the numerical value is input again. As shown in FIG. 3, the force- A new deflection diagram is created and stored in the storage unit 42. Then, the control process from step S11 is performed again.

It should be noted that the total amount of the cutting allowance ap for the workpiece W as the raw material taken out from the mold does not change even if the taking allowance ap at the finishing stage is adjusted. Therefore, when the set value of the allowance a in the finish machining stage is adjusted, the allowance a in the roughing step and the intermediate machining stage is also adjusted.

As described in detail above, according to the cutting device 10 and the cutting control process thereof in the present embodiment, the following effects can be obtained.

(1) The cutting power P having a preset target bending amount μa is set as the target cutting power Pa. The cutting power P is measured each time cutting is performed using the tool 21, and based on the peak value and the target cutting power Pa, the peak value of the next cutting power P is set to the target cutting power Pa. The allowance a and the feed amount f are adjusted. As a result, even if the cutting edge portion 25 changes with time due to repeated cutting, the cutting accuracy can be ensured without trial and error of the cutting conditions of the allowance a and the feed amount f for each cutting.

(2) The target back component force Fa is obtained by substituting the preset target deflection amount μa into the equation (1) showing the relationship between the back component force F and the deflection amount μ, and the target back component force Fa is used as the back component force Fa. The target cutting power Pa is calculated by substituting into the equation (2) showing the relationship between the component force F and the cutting power P. Thereby, the target cutting power Pa can be preferably calculated.

(3) The coefficient k in the above formula (1) is obtained by applying a force assuming a back component force F at the time of cutting to the tip of the tool 21 installed on the tool post 23 before performing the first cutting. , It is obtained by measuring the amount of deflection μ at that time. Therefore, the coefficient k in the equation (1) is obtained as an eigenvalue of the tool side unit 11 including the tool 21 for executing the cutting process. Since the deflection of the tool 21 during cutting is affected by the rigidity of the tool holder 22 and its peripheral parts on the tool holding side, the target back component force Fa is set in consideration of these. As a result, the cutting accuracy can be further improved.

(4) When resetting the set values of the allowance a and the feed amount f, the adjustment of the allowance ap is prioritized in the case of continuous cutting, and the setting of the allowance ap is adjusted in the case of intermittent cutting. In continuous cutting, when the feed amount f is adjusted to be small, the time required for cutting is extra and the processing efficiency is lowered. Therefore, the machining efficiency can be maintained by adjusting the setting of the allowance ap. Further, in the case of intermittent cutting, the swing of the tool 21 is reduced by adjusting the take-off allowance ap instead of the feed amount f which has almost no effect on the swing of the tool 21 which affects the roundness. The accuracy of roundness can be ensured.

(5) In the case of continuous cutting, the "1 / N" (N is a natural number of 2 or more) is set as the target deflection amount μa from the allowable tolerance, and in the case of intermittent cutting, the allowable perfect circle. From the degree, the "1 / N" (N is a natural number of 2 or more) is set as the target deflection amount μa. In continuous cutting, the tool 21 is constantly bent during the cutting process, and the deflection becomes constant each time the cutting process is repeated, which affects the tolerance of the workpiece W. Therefore, by setting the target deflection amount μa based on the tolerance, the influence of the deflection on the tolerance can be reduced. Further, in intermittent cutting, since the tool 21 swings during cutting, when cutting the inner peripheral surface of the work piece W having a circular shape, the roundness is affected and the cutting process is repeated. It also affects the amount of vibration of the cutting. Therefore, by setting the target deflection amount μa based on the roundness, the influence of the swing on the roundness can be reduced.

The present invention is not limited to the cutting device 10 of the above embodiment and its cutting control process, and may be implemented as follows, for example.

(A) In the above embodiment, the coefficient k of the formula (1) showing the relationship between the back component force F (N) and the bending amount μ (mm) is set to the tip of the tool 21 before the first cutting process is performed. It is obtained by applying a force assuming a back component force F during cutting to the portion (cutting edge portion 25) and measuring the amount of deflection μ at that time. Instead of this, a coefficient k predicted in consideration of the material and shape of the tool 21, the rigidity of the tool holding side such as the tool holder 22, and the like may be used.

(B) In the above embodiment, it is assumed that the workpiece W is a cylindrical member and the entire inner peripheral surface thereof is cut. However, only a part (boring) of the inner peripheral surface of the cylindrical member is formed. It may be applied when cutting or cutting the outer surface.

10 ... cutting device, 21 ... tool, 23 ... tool post, 41 ... control unit (target cutting power setting means, adjusting means, control means).

Claims (5)

A cutting edge portion is provided at the tip portion of the tool protruding from the tool post, the cutting edge portion faces in a direction intersecting the protruding direction of the tool, and the cutting edge portion is pressed against the workpiece to be machined. A cutting device that cuts objects
A target cutting power setting means for setting a target cutting power for setting the bending amount of the tip portion to a preset target bending amount when the tool is pressed against the workpiece for cutting.
Based on the peak value of cutting power measured each time cutting is performed using the tool and the target cutting power, the allowance and the allowance so that the peak value of the next cutting power becomes the target cutting power. An adjustment means to adjust the setting of at least one of the feed amounts, and
A control means for controlling a pressing operation during cutting by the tool based on a set value adjusted by the adjusting means, and a control means.
A cutting device characterized by being equipped with. The target cutting power setting means has a relational expression (1) "μ = kF" (k is a coefficient) indicating the relationship between the back component force F (N) and the bending amount μ (mm) for the target bending amount. ) Is the target back component force obtained by substituting it into), and the relational expression (2) “F = α × 60,000 × P / V” (α is The cutting apparatus according to claim 1, wherein the target cutting power is calculated by substituting the back component force conversion coefficient (V (m / min) is the cutting speed). The coefficient k of the relational expression (1) is obtained by applying a force assuming a back component force at the time of cutting to the tip portion of the tool installed on the tool post and measuring the amount of bending at that time. 2. The cutting apparatus according to claim 2. A cutting edge portion is provided at the tip portion of the tool protruding from the tool post, the cutting edge portion faces in a direction intersecting the protruding direction of the tool, and the cutting edge portion is pressed against the workpiece to be machined. It is a cutting control method for cutting equipment that cuts objects.
By applying a force assuming a back component force during cutting to the tip portion of the tool installed on the tool post and measuring the amount of deflection of the tip portion at that time, the back component force F (N) is obtained. The relational expression (1) "μ = kF" (k is a coefficient) which shows the relation with the bending amount μ (mm) about the said tool was obtained.
Substituting the preset target deflection amount into the relational expression (1) to obtain the target back component force,
The target back component force is the relational expression (2) “F = α × 60,000 × P / V” (α is the back component force conversion coefficient, which indicates the relationship between the back component force F and the cutting power P (KW). V (m / min) is substituted for cutting speed) to calculate the target cutting power.
Based on the peak value of the cutting power measured each time cutting is performed using the tool and the value of the target cutting power, the peak value of the next cutting power is set to the value of the target cutting power. , Adjust the settings of at least one of the allowance and feed amount,
A cutting control method characterized in that the pressing operation during cutting by the tool is controlled based on the adjusted set value. The target amount of deflection is set to "1 / N" (N is a natural number of 2 or more) from the allowable tolerance when the cutting process is continuous cutting, and is allowed when the cutting process is intermittent cutting. The cutting control method according to claim 4, wherein the degree of roundness is set to "1 / N" (N is a natural number of 2 or more).

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