JP4398070B2 - Numerical control device and groove processing method for machine tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a numerical control device and a groove machining method for a machine tool.
[0002]
[Prior art]
The free-form surface of a mold is processed by high-speed milling using a cutting tool such as an end mill mounted on a CNC machine tool such as a machining center.
In the processing of such a free-form surface of a mold, for example, a groove for a rib having a predetermined cross-sectional shape along the free-form surface is often processed.
To cut a groove along the free-form surface of a mold, the cutting tool is moved back and forth between the ends of the groove with respect to the workpiece. A program that describes all the cutting tool paths for the workpiece must be created. There is.
[0003]
[Problems to be solved by the invention]
For this reason, the groove processing program as described above has a disadvantage that the program size becomes large. That is, since it is necessary to create NC data obtained by linearly interpolating all the paths of the cutting tool for machining the entire groove to be machined, the program size becomes enormous. In particular, when the surface of the workpiece for machining the groove is a free-form surface, the amount of NC data is enormous.
When the program size is large, a program error is likely to occur, and there is a problem that the machining surface accuracy of the groove is lowered due to a wrong path of the cutting tool or a wrong speed of the cutting tool.
[0004]
The present invention has been made in view of the above-described problems, and can provide a numerical control device for a machine tool capable of easily and quickly creating a groove machining program and reducing the program size. An object is to provide a groove processing method.
[0005]
[Means for Solving the Problems]
A numerical control device for a machine tool according to the present invention is a numerical control device for a machine tool that includes an analysis execution unit that analyzes and executes a machining program that defines a machining procedure of a workpiece by a tool and generates a control command for driving the machine tool. The analysis execution unit analyzes a groove machining command code for instructing machining of a groove having a predetermined cross-sectional shape along the surface of the workpiece, and processes the workpiece added to the groove machining command code. Reference path program for specifying the reference path of the groove, cross-sectional shape data for specifying the cross-sectional shape of the groove including the inclination of the right side surface and the left side surface of the groove, and processing conditions for processing the groove based on the data, said generating a control command for commanding the relative movement between the workpiece and the tools needed to complete machining of the grooves, the analyzing unit, the based on the processing condition data and the cross-sectional shape data, Interference between the side surface of the sushi and the groove is checked or not occur.
[0006]
The analysis execution unit creates a reverse path program for specifying a reverse path that reverses the reference path of the groove from the reference path program, and uses the reference path program and the reverse path program to process all of the grooves. Generate the control commands necessary for
[0007]
The numerical control device for a machine tool according to the present invention has storage means for storing and holding the reverse path program.
[0008]
Preferably, the analysis execution unit generates feed speed data of a tool that moves in the reverse path so that a feed speed of the tool that moves in the reverse path matches a feed speed of the tool that moves in the reference path. To do.
[0009]
The analysis execution unit uses the reference path program and the reverse path program alternately to offset the tool movement path with respect to the workpiece in the groove width direction with respect to the reference path or the reverse path, while keeping the same in the groove. A control command for machining the surface with a predetermined cut amount is generated.
[0011]
The analysis execution unit calculates an offset amount of the tool in the groove width direction so that the tool contacts the side surface of the groove based on the cross-sectional shape data and the machining condition data.
[0012]
The cross-sectional shape data includes the width of the opening of the groove, the width of the bottom of the groove, the inclination of each side surface of the groove, and the initial processing position of the groove.
[0013]
The machining condition data includes a cutting depth in the depth direction of the tool groove, offset information for specifying the offset amount in the width direction of the tool groove, cutting edge information for specifying the type of the cutting edge of the tool, tool diameter Contains information.
[0014]
The surface of the workpiece is a free-form surface.
[0015]
A grooving method by a machine tool according to the present invention is a grooving method by a machine tool provided with a numerical control device that drives a machine tool according to a machining program and executes machining of the workpiece, and is a predetermined along the surface of the workpiece. A reference path program for specifying a reference path of a groove to be processed into a workpiece, and a groove path including a slope of the right side surface and the left side surface of the groove. A program creation step for creating a groove machining program by adding cross-sectional shape data for specifying a cross-sectional shape and machining condition data for machining the groove, and the groove machining program to the numerical controller Download and analyze this grooving program, generate a control command to command the relative motion between the workpiece and the tool necessary for the entire machining of the groove, and perform the grooving It has a line step, wherein the execution step, on the basis of the sectional shape data and the machining condition data, it is checked whether the interference is not generated between the side surface of the tool and the groove.
[0016]
The execution step creates a reverse path program for specifying a reverse path that reverses the reference path of the groove from the reference path program, and uses the reference path program and the reverse path program to perform all processing of the groove. Generate the necessary control commands.
[0017]
In the grooving method using a machine tool according to the present invention, the generated reverse path program is stored and held in a storage means included in the numerical control device.
[0018]
Preferably, the execution step generates feed rate data of a tool moving on the reverse path so that a feed speed of a tool moving on the reverse path matches a feed speed of a tool moving on the reference path. .
[0019]
The execution step uses the reference path program and the reverse path program alternately, and offsets the movement path of the tool relative to the workpiece in the width direction of the groove with respect to the reference path or the reverse path. Is generated with a predetermined cutting amount.
[0021]
The execution step calculates an offset amount of the tool in the groove width direction for the tool to contact the side surface of the groove based on the cross-sectional shape data and the machining condition data.
[0022]
The cross-sectional shape data includes the width of the opening of the groove, the width of the bottom of the groove, the inclination of each side surface of the groove, and the initial processing position of the groove.
[0023]
The machining condition data includes a cutting depth in the depth direction of the tool groove, offset information for specifying the offset amount in the width direction of the tool groove, cutting edge information for specifying the type of the cutting edge of the tool, tool diameter Contains information.
[0024]
The groove processing method of the present invention processes a groove in a workpiece having a free curved surface.
[0025]
In the present invention, when a groove is machined along the surface of the workpiece, a reference path program for specifying a reference path of the groove, a cross-sectional shape data for specifying a cross-sectional shape, and processing conditions are specified in the groove processing command code. A program for grooving is created by adding data. When this grooving program is downloaded to a numerical control device, analyzed, and executed, a control command for instructing relative motion between the workpiece and the tool necessary for the entire machining of the groove is generated, and the groove is machined.
As described above, in the present invention, the groove reference path, the groove cross-sectional shape and the machining are not created in the groove machining command code, rather than creating a program that describes all the relative motions of the workpiece and the tool for the groove machining. All the grooves are processed simply by specifying the conditions.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an example of a machining center as a machine tool driven by a numerical control apparatus of the present invention.
The machining center shown in FIG. 1 is a so-called portal-type machining center, and includes a cross rail 37 that is supported by each axis of a portal column 38 so that both ends thereof are movable. A ram 45 is provided so as to be movable in the vertical direction (Z-axis direction) via the saddle 44 formed.
[0027]
The saddle 44 is provided with a nut portion (not shown) through the inside of the cross rail 37 in the horizontal direction, and a ball screw 41 is screwed to the nut portion. An X-axis servomotor 18 is provided at the end of the ball screw 41, and the ball screw 41 is rotationally driven by the X-axis servomotor 18.
The rotation of the ball screw 41 enables the saddle 44 to move in the X-axis direction, thereby moving the ram 45 in the X-axis direction.
[0028]
Further, the saddle 44 includes a nut portion (not shown) in the vertical direction, and a ball screw 42 is screwed to the nut portion. A Z-axis servo motor 20 is provided at the end of the ball screw 42. The ball screw 42 is rotationally driven by the Z-axis servomotor 20, whereby the ram 45 movably provided on the saddle 44 is moved in the Z-axis direction.
[0029]
A spindle motor 31 is built in the ram 45, and the spindle motor 31 rotationally drives a cutting tool T such as an end mill provided at the tip of the ram 45.
A Y-axis table 35 is provided below the ram 45 so as to be movable in the Y-axis direction. The Y-axis table 35 includes a nut portion (not shown), and a ball screw (not shown) provided along the Y-axis direction is screwed to the nut portion, and the Y-axis servo motor 19 is connected to the ball screw. Has been.
The Y-axis table 35 is moved in the Y-axis direction by the rotational drive of the Y-axis servomotor 19.
[0030]
The drive control of the X-axis servomotor 18, the Y-axis servomotor 19 and the Z-axis servomotor 20 is performed by the NC device 1.
The gate column 38 is formed with a female thread portion (not shown), and the cross rail 37 is moved up and down by rotationally driving a ball screw 32 a to be engaged with the gate column 38 by the cross rail lifting motor 32.
Further, the cutting tool T can be changed to various ones by an automatic tool changer (ATC) 39, and various attachments can be changed to various ones by an automatic changer (AAC) 40.
[0031]
FIG. 2 is an explanatory diagram showing a basic configuration of the NC apparatus 1 according to an embodiment of the numerical control apparatus of the present invention.
2, the NC device 1 includes a program storage unit 2, a program analysis execution unit 3, an X-axis servo control unit 12, a Y-axis servo control unit 13, a Z-axis servo control unit 14, an X-axis servo driver 15, A Y-axis servo driver 16 and a Z-axis servo driver 17 are provided.
An X-axis servo motor 18, a Y-axis servo motor 19 and a Z-axis servo motor 20 are connected to the X-axis servo driver 15, the Y-axis servo driver 16 and the Z-axis servo driver 17. The X-axis servo motor 18, the Y-axis servo motor 19 and the Z-axis servo motor 20 are respectively provided with rotational position detectors 18a, 19a and 20a such as an optical rotary encoder, for example.
[0032]
The program storage unit 2 stores and holds an NC program that defines a machining procedure for a workpiece with a tool.
For example, the program analysis execution unit 3 analyzes a machining program in which a machining procedure of a tool for machining a workpiece is programmed in a predetermined language, and obtains trajectory data having the obtained velocity information of the tool as a speed command (control) for each control axis. Command) and distribute it to each control axis. The specific configuration of the program analysis execution unit 3 will be described later.
[0033]
The X-axis servo control unit 12, the Y-axis servo control unit 13, and the Z-axis servo control unit 14 include a position loop, a speed loop, and a current loop.
The position loop is, for example, a rotational position detector that receives the position command (movement amount) of each control axis input from the program analysis execution unit 3 and detects these movement amounts and the rotational positions of the servo motors 18 to 20. A proportional operation is applied to the deviation from the position feedback signal from 18a to 20a (the position loop gain ω ₀ is applied), and this is output as a speed command for the speed loop.
For example, the speed loop performs a proportional operation and an integral operation on a deviation between the speed command and a difference value (speed feedback signal) for each sampling time of the position feedback signal from the rotational position detectors 18a to 18a to obtain a torque command. This is output to the current loop.
The current loop, for example, performs a proportional operation on the deviation between the output torque signal of each servo motor 18-20 converted from the drive current of each servo motor 18-20 and the torque command to obtain a current command. ~ 17 are converted into predetermined electrical signals and output.
The X, Y, and Z axis servo control units 12 to 14 are realized by software in this embodiment, but can also be realized by hardware.
[0034]
The X-axis servo driver 15, the Y-axis servo driver 16, and the Z-axis servo driver 17 convert drive currents obtained by amplifying current commands from the X, Y, and Z-axis servo control units 12 to 14 to X, Y, and Z servo motors 18 to 20 is output.
The X, Y, Z axis servo motors 18-20 are driven according to the drive current, and the rotational position detectors 18a-20a included in the X, Y, Z axis servo motors 18-20 are X, Y, Z axis servos. Detection pulses corresponding to the rotation amounts of the motors 18 to 20 are output to the X, Y, and Z axis servo control units 12 to 14.
As the rotational position detectors 18a to 20a, for example, an incremental rotary encoder or an absolute rotary encoder can be used. When an incremental rotary encoder is used, the rotary encoder outputs a position signal for each rotation as a rotation pulse signal, so the number of rotation pulse signals is set to X, Y, Z axis servo control units 12 to 14. The absolute position of the X-, Y-, and Z-axis servomotors 18 to 20 can be managed.
[0035]
Each of the above functions is a function inherently provided in a general NC device. Further, the machining program used for the NC apparatus is generally automatically created by a CAD system, an automatic programming system, a CAM system, etc., and the NC apparatus 1 via a predetermined storage medium or by communication means. To be downloaded.
[0036]
FIG. 3 is a diagram illustrating an example of a hardware configuration of the NC apparatus 1 illustrated in FIG.
Each function of the NC apparatus 1 shown in FIG. 2 is realized by hardware having a configuration as shown in FIG. 3, for example.
In FIG. 3, a microprocessor 21 includes a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, an interface circuit 24, a graphic control circuit 25, a display device 26, a keyboard 28, software keys 27 and the like via a bus. Connected.
The microprocessor 21 controls the entire NC device 1 according to the system program stored in the ROM 22.
[0037]
The ROM 22 stores a program for realizing the program analysis execution unit 3, the X, Y, and Z axis servo control units 12 to 14, and a system program for controlling the entire NC device 1.
In the RAM 23, a program stored in the ROM 22 is downloaded, various NC programs, data, and the like are stored. For example, correction amount data described later is stored.
[0038]
The graphic control circuit 25 converts the digital signal into a display signal and supplies it to the display device 26.
As the display device 26, for example, a CRT display device or a liquid crystal display device is used. The display device 26 displays a shape, machining conditions, a generated machining program, and the like when an operator creates a machining program by a manual operation in an interactive manner using the software key 27 or the keyboard 28.
The operator can create a machining program by inputting data in accordance with the contents (interactive data input screen) displayed on the display device 26.
On the screen of the display device 26, work or data received on the screen is displayed in a menu format. Which item to select in the menu is determined by pressing the software key 27 below the menu.
The keyboard 28 is used to input necessary data to the NC device 1.
[0039]
The interface circuit 24 converts a command such as a position command output from the microprocessor 21 into a predetermined signal and outputs it to the X to Z axis servo drivers 15 to 17.
The interface circuit 24 sequentially counts, for example, detection pulses from the position detectors 18 a to 20 a provided in the X to Z axis servomotors 18 to 20, converts them into predetermined digital signals, and outputs them to the microprocessor 21. .
[0040]
Next, a specific configuration of the above-described program analysis execution unit 3 will be described.
The program analysis execution unit 3 can decode a groove machining command code for instructing machining of a groove having a predetermined cross-sectional shape along the surface of the workpiece.
Here, an example of the format of the groove machining command code is shown below.
[0041]
G182 XYZRIJK ₁ K ₂ QPDEF $
[0042]
The groove machining command code G182 is a code for machining the groove TR using an end mill on a workpiece W having a free curved surface FS, for example, as shown in FIG.
[0043]
In the groove processing command code G182, $ is a reference path program for specifying the reference path BL from the point P1 at one end to the point P2 at the other end of the groove TR shown in FIG.
Specifically, the reference route program $ is, for example, a point sequence that specifies coordinates in the X, Y, and Z axis directions.
[0044]
X and Y are initial machining positions in the X-axis direction. Note that the initial machining position in the Z-axis direction is the current position.
[0045]
As shown in FIG. 4, Z is a coordinate in the Z-axis direction of a point P1 at one end of the reference path BL passing through the center of the opening of the groove TR along the free curved surface FS of the workpiece W.
As shown in FIG. 5, R is a coordinate of an R point (machining start point) in the Z-axis direction (depth direction) of the trench TR.
[0046]
As shown in FIG. 5, I is the width of the opening of the trench TR. It is assumed that the groove TR is a groove that is even on the left and right with respect to the reference path BL.
J is the depth from the opening of the trench TR to the bottom. That is, the distance from the point P1 to the bottom of the trench TR.
[0047]
K ₁ is the inclination of the left side surface TRa with respect to the traveling direction of the groove TR, and K ₂ is the inclination of the right side surface TRb with respect to the traveling direction of the groove TR.
When only _one of K ₁ and K ₂ is designated, K ₁ = K ₂ is assumed, and when neither K ₁ nor K ₂ is designated, K ₁ = K ₂ = 0. It is considered.
[0048]
Q is a cutting amount per one time of the tool T in the Z-axis direction. The cutting amount Q is set so as to satisfy the relationship of Q ≦ J with the depth J of the trench TR. Further, it is set to satisfy | R−Z | ≦ Q.
[0049]
P is an offset rate of the tool in the width direction of the groove TR. This offset rate P is set in the range of 0 <P ≦ 100%.
D is a tool diameter correction number. This tool diameter correction number is the diameter of the tool.
Therefore, D × P / 100 is the tool offset amount.
[0050]
E is a parameter that specifies the cutting edge of the tool. When E = 0, the tool is a ball end mill, and when E = 1, the tool is a flat end mill.
F is a feed speed when the tool is moved in the width direction of the groove TR and when moved in the Z-axis direction.
[0051]
Here, the above reference path program $ is an embodiment of the reference path program of the present invention, and the opening width I and depth J of the trench TR and the inclinations K ₁ and K ₂ of the side surfaces TRa and TRb are the cross-sectional shape data of the present invention. The initial position X, Y, the machining start position R, the coordinate Z in the Z-axis direction of the point P1, the cutting amount Q, the offset rate P, the tool correction number D, the tool edge specification parameter E, and the feed speed F are The processing condition data of the present invention is configured.
[0052]
The program analysis execution unit 3 includes the reference path program $ added to the groove machining command code G182, the opening width I and depth J of the groove TR, the inclinations K ₁ and K _{2 of the} side surfaces TRa and TRb, and the initial position. Based on X, Y, machining start position R, coordinate Z in the Z-axis direction of point P1, cutting amount Q, offset rate P, tool correction number D, tool edge specification parameter E, feed rate F, all the grooves TR A control command for commanding relative motion between the workpiece and the tool necessary for machining is generated.
[0053]
Reverse path program generation function Specifically, as shown in FIG. 4, the program analysis execution unit 3 specifies a reverse path INL that reverses the reference path BL of the groove TR from the reference path program $. A reverse path program IPR is created. That is, the reverse route program IPR is a program that specifies the route INL from the other end portion P2 to the one end portion P1 of the reference route BL.
[0054]
Further, when the program analysis execution unit 3 generates the reverse path program IPR, the reverse path INL is set so that the feed speed of the tool moving on the reverse path INL matches the feed speed of the tool moving on the reference path BL. The feed speed data of the tool that moves is generated.
The information on the feed speed of the tool moving on the reference path BL may be included in the reference path program $ or may be specified in the machining program by the F code.
When the program analysis execution unit 3 generates the reverse path program IPR, the reverse path program IPR is output to the program storage unit 2 as shown in FIG. 2, and the reverse path program IPR is temporarily stored and held. .
[0055]
Reciprocal motion command generation function The program analysis execution unit 3 generates a control command necessary for the entire machining of the groove TR using the reference path program $ and the reverse path program IPR.
Here, a method for generating a control command of the program analysis execution unit 3 will be described with reference to FIGS.
As shown in FIG. 6, the tool T is cut from the point R by the cut amount Q and moved to the start position Pa of (1).
From this position Pa, the program analysis execution unit 3 generates a control command for moving the tool T to the position Pb along the path T1 as shown in FIG. This route T1 is obtained by correcting the reference route BL specified by the reference route program $ with a predetermined offset amount in the cutting direction (Z-axis direction).
[0056]
After generating the control command to move to the position Pb, the program analysis execution unit 3 generates a command to move the tool T in the width direction of the groove TR, that is, a command to move from the position Pb to the position Pc.
The movement command from the position Pb to the position Pc is generated from the offset amount specified from the offset rate P and the tool correction number D and the feed speed F.
[0057]
After generating the control command for moving to the position Pc, the program analysis execution unit 3 generates a control command for moving the tool T to the position Pd along the path T2. This path T2 is obtained by correcting the reverse path INL specified by the reverse path program IPR with a predetermined offset amount in the cutting direction (Z-axis direction) and the width direction of the groove TR. Note that the route T2 and the route T1 are present in the same plane.
[0058]
After generating the control command to move to the position Pd, the program analysis execution unit 3 generates a command to move the tool T in the width direction of the groove TR, that is, a command to move from the position Pd to the position Pe.
The movement command from the position Pd to the position Pe is generated from the offset amount specified from the offset rate P and the tool correction number D and the feed speed F.
[0059]
After generating the control command for moving to the position Pe, the program analysis execution unit 3 generates a control command for moving the tool T to the position Pf along the path T3. This route T3 is obtained by correcting the reference route BL specified by the reference route program $ with a predetermined offset amount in the cutting direction (Z-axis direction) and the width direction of the trench TR. Note that the path T3 and the above-described paths T1 and T2 exist in the same plane.
[0060]
After generating the command to move the tool T to the position Pf, the program analysis execution unit 3 generates a command to move the tool T from the position Pf to the position Pb.
Further, the program analysis execution unit 3 moves the tool T to the position Pg in the Z-axis direction with the cutting amount Q, and moves the same surface in the groove TR with the predetermined cutting amount Q at the positions (1) to (3). A command similar to the command to be processed is generated. That is, as shown in FIG. 6, a command for machining the same surface in the groove TR with a predetermined cutting amount Q is generated while the tool T is offset to positions (4), (5) and (6).
[0061]
As shown in FIG. 6, the program analysis execution unit 3 moves the tool T to the positions of (7), (8), and (9), and moves the tool T to the initial position after machining to the bottom of the groove TR. Generate directives.
[0062]
Interference check function The program analysis execution unit 3 checks whether interference occurs between the tool T and the side surfaces TRa and TRb of the groove TR based on the cross-sectional shape data of the groove TR and the machining condition data. To do.
That is, the program analysis execution unit 3 moves the tool T in the Z-axis direction with the cutting amount Q and offsets it in the groove width direction, so that the tool T does not bite into both side surfaces TRa and TRb of the groove TR. The offset amount of the tool T in contact is calculated.
[0063]
Here, the positions of both side surfaces TRa and TRb of the trench TR can be expressed by the following equation (1). Note that m is the inclination of both side surfaces TRa and TRb, and is determined from the above K ₁ and K ₂ . B is a constant.
[0064]
[Expression 1]
y = mx + b (1)
[0065]
The position of the tool T can be expressed by the following equation (2). P ₀ is the position of the tool T in the groove direction, R ₀ is the diameter of a predetermined circle, and Q ₀ is the position of the tool T in the cutting direction (Z-axis direction).
[0066]
[Expression 2]
R ₀ ² = (x−P ₀ ) ² + (y−Q ₀ ) ² (2)
[0067]
Substituting equation (1) for y in equation (2) yields the following equation (3).
[0068]
[Equation 3]
R ₀ ² = (x−P ₀ ) ² + (mx + b−Q ₀ ) ²
= X ² -2xP ₀ + P ₀ ² + m ² x ² + 2m (b−Q ₀ ) + (b−Q ₀ ) ²
= (M ² +1) x ² + (2m (b−Q ₀ ) −2P ₀ ) x + P ₀ ² + (b−Q ₀ ) ² (m ² +1) x ² + (2m (b−Q ₀ ) −2P ₀ ) x
+ P ₀ ² + (b−Q ₀ ) ² −R ₀ ² = 0 (3)
[0069]
In order for the tool T and the side surfaces TRa and TRb of the groove TR to contact each other, the discriminant D _{0 in the} above equation (3) may be zero. From this, the following equation (4) is obtained.
[0070]
[Expression 4]
D ₀ = m ² P ₀ ² + 2m (b−Q ₀ ) P ₀ + b ² −2bQ ₀
+ Q ₀ ² −m ² R ₀ ² −R ₀ ² = 0 (4)
[0071]
In equation (4), when solving for P _{0 using} the even solution formula, the solution shown in equation (5) below is obtained.
[0072]
[Equation 5]
P ₀ = {− (b−Q ₀ ) ± R ₀ (m ² +1) ^1/2 } / 2 (5)
[0073]
Here, there are two solutions of P ₀ . Among these, {− (b−Q ₀ ) −R ₀ (m ² +1) ^1/2 } / 2 is an intersection position in the groove width direction when the tool T and one side surface of the groove TR are in contact with each other. {− (B−Q ₀ ) + R ₀ (m ² +1) ^1/2 } / 2 is the intersection position in the groove width direction when the tool T and the other side surface are in contact with each other.
[0074]
The program analysis execution unit 3 obtains the position where the tool T and the side surface of the groove TR are in contact with each other by the above-described procedure, and prevents the tool T from interfering with the side surface of the groove TR.
[0075]
Next, an example of a groove machining method using the machining center having the above-described configuration will be described with reference to a flowchart shown in FIG.
First, an NC program for grooving is created using the above-described grooving command code G182 (step S1). That is, in the main machining program MPR, a program in which the reference path program $, the cross-sectional shape data of the groove TR, and the machining condition data for machining the groove TR are added to the groove machining command code G182.
[0076]
Next, the created NC program is downloaded to the NC device 1, and this NC program is stored in the program storage unit 2 (step S2).
Next, the program analysis execution unit 3 of the NC apparatus 1 reads the NC program stored in the program storage unit 2, analyzes the groove machining command code G182 included in this NC program and information added thereto, and The reverse path program IPR is generated (step S3).
At this time, feed speed data of the tool T that moves on the reverse path INL is generated so that the feed speed of the tool T that moves on the reverse path INL matches the feed speed of the tool that moves on the reference path BL.
The generated reverse path program IPR is stored in the program storage unit 2.
[0077]
Next, the program analysis execution unit 3 generates a control command for moving the tool T to the R point described above (step S4). Thereby, the tool T moves to the R point.
[0078]
Next, the tool T is moved relative to the workpiece by the cutting amount Q in the Z-axis direction (step S5), and the position in the groove width direction where the tool T and the side surfaces TRa and TRb of the groove TR to be processed contact in the same plane. P ₀ is calculated based on the above formulas (1) to (5) (step S6).
[0079]
Next, the program analysis execution unit 3 calculates an offset amount in the groove width direction for correcting the reference route BL or the reverse route INL defined by the reference route program $ or the reverse route program IPR (step S7).
Next, the corrected reference route program $ or reverse route program IPR in which the reference route BL or the reverse route INL is offset by the calculated offset amount is executed (step S8).
By executing these programs, a control command for moving the tool T to the workpiece along a predetermined path is generated and output to the servo control unit of each axis. As a result, the tool T reciprocates with respect to the workpiece, and grooving is performed in the same plane.
[0080]
During this reciprocating operation, it is determined whether the tool T has reached the side surfaces TRa and TRb of the groove TR using the calculated position P ₀ (step S9).
When the tool T has reached the side surfaces TRa and TRb of the groove TR, since the processing in the surface is completed, the program analysis execution unit 3 moves the tool T to the groove center which is the reference position. A command is generated (step S10).
[0081]
Next, it is determined whether the depth processed by the tool T has reached the bottom of the groove TR (step S11).
If the bottom of the groove TR has not been processed, a command for further cutting the tool T in the Z-axis direction with a cutting amount Q is generated (step S12), and the point where the tool contacts both side surfaces of the groove is calculated. A sequence for processing the groove TR by reciprocating operation is performed repeatedly while offset in the groove width direction.
[0082]
If the bottom of the groove TR has been processed, the processing moves to the processing start point (step S13), and the groove processing ends.
[0083]
Through the above-described steps, the tool T sequentially moves to, for example, the positions {circle around (1)} to {circle around (9)} shown in FIG. 6, and the grooves TR are processed step by step from the surface of the workpiece to a deep position.
[0084]
As described above, according to the present embodiment, all the processing of the groove TR is performed only by adding the reference path program $, the processing condition data, and the groove cross-sectional shape data to the groove processing command code G182. For this reason, it becomes easy to create a program for grooving, and the program size can be greatly reduced as compared with the case where all the tool paths are described. In addition, programming errors can be prevented as much as possible, and mistakes in the tool path and speed are almost eliminated.
In the present embodiment, when the reverse path program IPR is automatically generated from the reference path program $, the feed speed information is generated so that the feed speed is the same between the reference path and the reverse path. The machined surface is not disturbed by
Furthermore, in this embodiment, since the interference between the side surface of the groove to be processed and the tool is checked, the size of the processed groove does not differ from the required groove size.
[0085]
In the above-described embodiment, the case where the groove is machined in the free curved surface FS of the workpiece has been described, but the present invention is naturally applicable to the case where the groove is machined in the plane of the workpiece.
Further, the machine tool is not limited to the machining center, and can be applied to other machine tools.
[0086]
【The invention's effect】
According to the present invention, it is possible to quickly and easily create a groove machining program.
According to the present invention, the program size of the groove machining program can be reduced, and the occurrence of programming errors can be reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of a machine tool to which the present invention is applied.
FIG. 2 is a diagram showing a basic configuration of the NC apparatus 1;
FIG. 3 is a diagram illustrating a hardware configuration of the NC apparatus 1;
FIG. 4 is a perspective view showing an appearance of an example of a workpiece to be grooved.
FIG. 5 is a diagram for explaining a sectional shape of a groove and processing conditions.
FIG. 6 is a cross-sectional view showing a moving path of a tool for grooving.
FIG. 7 is a perspective view showing a movement path of a tool for grooving.
FIG. 8 is a flowchart for explaining an example of the procedure of the groove machining method by the machine tool of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... NC apparatus 2 ... Program memory | storage part 3 ... Program analysis execution part

Claims (18)

A numerical control device for a machine tool including an analysis execution unit that analyzes and executes a machining program that defines a machining procedure of a workpiece by a tool and generates a control command for driving the machine tool,
The analysis execution unit analyzes a groove machining command code for instructing machining of a groove having a predetermined cross-sectional shape along the surface of the workpiece, and is added to the groove machining command code, and a reference for a groove to be machined into the workpiece A reference path program for specifying a path, cross-sectional shape data for specifying a cross-sectional shape of the groove including inclinations of a right side surface and a left side surface of the groove, and processing condition data for processing the groove Based on this, a control command for commanding the relative motion between the workpiece and the tool necessary for the entire machining of the groove is generated ,
The analysis execution unit is a numerical control device for a machine tool that checks whether interference occurs between a tool and a side surface of a groove based on the cross-sectional shape data and the machining condition data . The analysis execution unit creates a reverse path program for specifying a reverse path that reverses the reference path of the groove from the reference path program, and uses the reference path program and the reverse path program to process all of the grooves. The numerical control device for a machine tool according to claim 1, wherein a control command necessary for the machine tool is generated. The numerical control device for a machine tool according to claim 2, further comprising storage means for storing and holding the reverse path program. The analysis execution unit generates feed speed data of a tool that moves in the reverse path so that a feed speed of a tool that moves in the reverse path matches a feed speed of a tool that moves in the reference path. Or a numerical control device for a machine tool according to 3; The analysis execution unit uses the reference path program and the reverse path program alternately to offset the tool movement path with respect to the workpiece in the groove width direction with respect to the reference path or the reverse path, while keeping the same in the groove. The numerical control device for a machine tool according to any one of claims 2 to 4, wherein a control command for machining the surface with a predetermined cut amount is generated. The analysis execution unit calculates an offset amount of the tool in the groove width direction so that the tool contacts the side surface of the groove based on the cross-sectional shape data and the machining condition data.
A numerical control device for a machine tool according to any one of claims 1 to 5 . The cross-sectional shape data includes the width of the groove opening, the width of the bottom of the groove, the inclination of each side surface of the groove, and the initial processing position of the groove.
A numerical control device for a machine tool according to any one of claims 1 to 6 . The machining condition data includes a cutting depth in the depth direction of the tool groove, offset information for specifying the offset amount in the width direction of the tool groove, cutting edge information for specifying the type of the cutting edge of the tool, tool diameter Contains information and
The numerical control apparatus of the machine tool in any one of Claims 1-7 . The surface of the workpiece is a free-form surface
The numerical control apparatus of the machine tool in any one of Claims 1-8 . A groove machining method by a machine tool provided with a numerical control device that drives a machine tool according to a machining program and executes machining of a workpiece,
A reference path program for specifying a reference path of a groove to be machined in the workpiece, and a right side surface and a left side surface of the groove, to a groove machining command code for instructing machining of a groove having a predetermined cross-sectional shape along the surface of the workpiece A program creation step for creating a groove machining program by adding cross-sectional shape data for specifying the cross-sectional shape of the groove including the inclination of the groove and machining condition data for machining the groove;
The groove machining program is downloaded to the numerical control device, the groove machining program is analyzed, a control command for instructing relative movement between the workpiece and the tool necessary for the entire machining of the groove is generated, and the groove machining is performed. anda execution step of performing,
The execution step is a grooving method by a machine tool that checks whether interference occurs between the tool and the side surface of the groove based on the cross-sectional shape data and the machining condition data. The execution step creates a reverse path program for specifying a reverse path that reverses the reference path of the groove from the reference path program, and uses the reference path program and the reverse path program to perform all processing of the groove. Generate necessary control commands
The groove processing method by the machine tool of Claim 10 . The generated reverse path program is stored and held in the storage means included in the numerical controller.
The groove processing method by the machine tool of Claim 11 . The execution step generates feed rate data of a tool that moves on the reverse path so that a feed rate of the tool that moves on the reverse path matches a feed rate of a tool that moves on the reference path.
The groove processing method by the machine tool of Claim 11 or 12 . The execution step uses the reference path program and the reverse path program alternately, and offsets the movement path of the tool relative to the workpiece in the width direction of the groove with respect to the reference path or the reverse path. Generates a control command to process a workpiece with a predetermined cut amount
The groove processing method by the machine tool in any one of Claims 11-13 . The execution step calculates an offset amount of the tool in the groove width direction for the tool to contact the side surface of the groove based on the cross-sectional shape data and the machining condition data.
The groove processing method by the machine tool of Claims 10-14 . The cross-sectional shape data includes the width of the groove opening, the width of the bottom of the groove, the inclination of each side surface of the groove, and the initial processing position of the groove.
The groove processing method by the machine tool in any one of Claims 10-15 . The machining condition data includes a cutting depth in the depth direction of the tool groove, offset information for specifying the offset amount in the width direction of the tool groove, cutting edge information for specifying the type of the cutting edge of the tool, tool diameter Contains information and
The groove processing method by the machine tool in any one of Claims 10-16 . Machining grooves in workpieces with free-form surfaces
The groove processing method by the machine tool in any one of Claims 10-17 .

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