JP5055715B2 - NC controller for wire electrical discharge machining - Google Patents

Description

  The present invention relates to control when a predetermined shape is continuously cut using a wire electric discharge machine, and more particularly, to a control method and a control device for an NC control device that switches machining conditions at a cut-off portion.

PCD (diamond sintered body) and cBN (cubic boron nitride) have high hardness characteristics and excellent wear resistance, and are used for the cutting edge portion of cutting tools. Since it is molded into a bonded disk, it needs to be cut out from a disk shape to a cutting edge shape of the cutting tool in order to use it as a cutting tool.
Since PCD and cBN materials have high hardness, a wire electric discharge machine suitable for processing high-hardness workpieces is used for cutting out from materials. However, PCD and cBN materials are expensive. In order to cut out a workpiece with as many cutting edges as possible from a limited size workpiece, a complicated machining path is formed like a one-stroke drawing, leaving as little uncut parts and edges as possible. A processing method that cuts the processed products sequentially is performed.
As a processing method of the same type, Japanese Patent Laid-Open No. 2002-263958 has been proposed.

JP 2002-263958 A

When cutting a larger number of chips than a PCB sintered body disk or a cBN sintered body disk, it is generally possible to use P1 → P2 → P3 → P1 by using a one-stroke processing program as shown in FIG. Chip A is cut off, and then P1 → P4 → P3 and chip B are processed, and the chip is cut off at P3.
Here, when a chip cut-off portion is defined as a cut-off point, when many chips are adjacent to each other, a place where P3 is not a cut-off point in chip A can be a cut-off point of another chip (for example, chip B). There are many.
With such a cut-off point, chipping or cracking is likely to occur at the moment of cutting when processing is performed under strong conditions, so it is necessary to perform processing under conditions that do not cause chipping at the cut-off point.
Therefore, since the cutting process program from the disk to the cutting edge shape is continuous and complicated with a single stroke, the modification to change to a weak machining condition for each cutting point requires a huge amount of work and is a realistic method. As a result, the entire circumference was processed under the condition that no chipping occurred at the cut-off point.

In addition, there is a function in which the condition is automatically lowered at the corner, but this function is controlled by the angle between the current block and the next block.
That is, in the case of processing with a one-stroke program such as P1->P2->P3->P1-> P4, the movement is changed to a condition suitable for the angle inside P3-P1-P4 in the movement of P3->P1-> P4.
However, the P1 portion is also a corner portion made of P2-P1-P3 of the chip A. If the angles of P3-P1-P4 and P2-P1-P3 are different, machining is performed under conditions that match the angles of P3-P1-P4. As a result, cracks and chipping may occur on the chip A side, and this function cannot be used, and the entire circumference has been processed under weak conditions as described above.

  In addition, there is an optimum feed function that changes the feed speed depending on the discharge condition, and the machining time can be shortened by strengthening the conditions. However, chipping and cracking are likely to occur at the cutting point, so The cutting point has to be processed under weak conditions so that the chip is not lost, and there is a problem that the processing time becomes long, and productivity cannot be improved.

  The present invention solves these problems, and reduces the user's machining program creation work, changes the machining conditions suitable for a predetermined point, and uses other conditions at other points. This makes it possible to improve chip productivity.

  The NC control device according to the present invention analyzes a machining NC program memory for storing machining NC programs composed of a plurality of blocks created by a user and the machining NC program for each block, and connects them via an input / output circuit. An NC program analyzing unit for giving a command to the control means to be operated, and in an NC controller for wire electric discharge machining that performs wire electric discharge machining using the machining NC program, as a result of analysis by the NC program analyzing unit, A machining condition switching control unit that calculates the movement amount in the block when the movement command at the time of machining is performed and this movement amount reaches a predetermined distance is switched to a separately defined machining condition. It is provided.

According to the present invention, since the mode for automatically changing the machining conditions is provided in the front and rear portions in the line segment, the user can easily change the machining conditions of the cut-off portion without creating a complicated NC program. This improves the workability of NC program creation.
Further, in the processing, the processing conditions at the cut-off portion are optimized, and at the portion capable of high-speed processing, the processing time per chip can be shortened and the chip productivity can be improved.

Embodiment 1 FIG.
Embodiments of a wire electric discharge machine and a wire electric discharge machine according to the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the wire electric discharge machine according to the first embodiment. Normally, the user creates a machining NC program on the operation board 4, assigns a name to the machining NC program memory 9, registers the saved program name as a program to be executed, and presses the start key.
With the start key, the NC controller 1 reads the program registered for start execution from the machining NC program memory 9 and analyzes it.
As a result of the analysis, the NC control device 1 adjusts the shaft control device 2, the machining power source 3, the flow rate control device 11, the wire recovery in accordance with commands such as a machining condition change command, a machining fluid command, a wire feed command, a machining start command, and a movement command. By controlling the control device 10 and the like, the machining power supply 3 is supplied while supplying the machining liquid 13 from the machining liquid tank 12 to the machining gap formed by the workpiece 6 (workpiece) placed on the wire electrode 5 and the table 7. The discharge current pulse is further supplied, and the workpiece is processed into an arbitrary shape by the electric discharge generated in the gap.

Next, a schematic operation of the NC control device 1 in the present embodiment will be described.
FIG. 2 is a block diagram showing the configuration of the NC control device 1.
The NC control device 1 includes a central processing unit 14 (hereinafter referred to as a CPU 14) composed of a microprocessor, and stores NC control program memory 17, data such as various parameter values of machining conditions and axis movement values. The data memory 15 is connected to an input / output circuit 16 that is an interface unit with devices (such as the axis control device 2 and the machining power source 3) connected to the NC control device.
The NC control program memory 17 stores an input / output circuit program 20 for controlling the processing machine, such as a machining NC program analysis program 19, a movement amount calculation program 18, and an input / output command 16.

Next, functional blocks inside the NC control device 1 for realizing the machining condition switching control mode will be described with reference to the drawings.
When the start key is pressed on the operation board 4, the machining NC program analysis program 19 is executed by the CPU 14, and as is well known, a predetermined NC program created by the user is analyzed and executed for each block.
As a result of the analysis, in the case of a machining condition change command, the parameter value to be changed is read from the data memory 15 and the machining condition parameter and the flow rate parameter are output from the input / output circuit 16 to the machining power source 3 and the flow rate control device 11.
In the case of the machining fluid start command, the operation start command is sent from the input / output circuit 16 to the flow control device 11.
In the case of a wire feed command, the input / output circuit 16 commands the wire recovery control device 10 to start operation.
In the case of a machining start command, the input / output circuit 16 commands the machining power supply 3 to start the operation.
In the case of the axis movement command, the movement amount calculation program 18 calculates the movement amount for each predetermined period, and the input / output circuit program 20 instructs the movement amount to the shaft drive control device 2 from the input / output circuit, and the shaft drive motor. 8a and 8b are controlled to drive the table on which the workpiece 6 is placed in the XY directions. At this time, the machining condition switching control program 21 is also executed, the value obtained by the movement amount calculation program 18 is checked, and if it is between the distance from the head point (Lα) or the distance from the last point (Lβ). When the determination is made, the parameters of the machining conditions (Eα, Eβ) of the distance portion are read from the data memory 15, and the parameter values are transferred from the input / output circuit 16 to the machining power supply 3 and the flow rate control device 11.
In addition, when it is outside the interval of Lα and Lβ, the parameter of the condition used originally is read from the data memory 15 and the parameter value is transferred from the input / output circuit 16 to the machining power source 3 and the flow rate control device 11.

For example, when performing the processing of FIG. 12, the chip A moves in the order of P1, P2, P3, P1, P4, P3,..., But the chip A has a cutoff point K1 at the end of the block that moves from P3 to P1. K1 is also the leading portion of the P1 → P2 block of chip A.
Chip B has a cut-off point K2 at the end of the P4 → P3 block, which is also the head of the P3 → P1 block of chip A.
As described above, the cut-off point is located at a position constituted by the head portion of a certain block and the last portion of the cut-off block, and there is a possibility that the head and the end of any block play a corner of the cut-off portion.

Therefore, in this embodiment, the machining condition switching control program 21 is provided in the NC control program memory 17, and when the machining NC program is analyzed and the movement command is executed, it is designated from the head point of the block as shown in FIG. A mode for switching the distance (Lα) and the near distance from the final point (Lβ) to the processing conditions (Eα, Eβ) of the distance portion.
By turning on this mode and processing all the blocks, processing can be performed under the condition that no chipping or cracking occurs at scattered cut points.

Next, the NC program when performing the machining shown in FIG. 12 in the prior art will be described with reference to FIG.
FIG. 3 is an NC program for processing chip A, and it is assumed that the wire is already at the P1 point.
This program shows an NC program representing a process of cutting a triangular chip A shape and a chip B shape from the position P1 as the origin (0, 0).

First, the machining NC program of FIG. 3 will be described in order.
B1 designates a condition number to be used when chip A and chip B are processed.
When the program is executed, the parameter corresponding to this number is read from the data memory 15 and the discharge pulse and the flow rate of the machining fluid are controlled via the machining power source 3 and the flow rate control device 11.
B2 indicates a machining fluid start, a wire feed start, and a machining start command.
B3 defines the movement command method as a relative value method. Here, the relative value method is a method of designating by a value obtained by subtracting the current position from the movement completion position.
B4 is a movement command for moving from the P1 coordinate (0.000, 0.000) to -1.5 mm in the X-axis direction and -2.598 mm in the Y-axis direction, and moves to the P2 coordinate (-1.500, -2.598).
B5 is a movement command for moving +3.0 mm in the X-axis direction from the P2 coordinate (-1.500, -2.598), and moves to the P3 coordinate (1.500, -2.598).
B6 is a movement command for moving from the P3 coordinate (1.500, -2.598) to -1.5 mm in the X-axis direction and +2.598 mm in the Y-axis direction, and finally moved to the P1 coordinate (0.000,0.000). Chip A is cut off.
B7 is a movement command for moving +3.0 mm in the X-axis direction from the P1 coordinate (0.000, 0.000), and moves to the P4 coordinate (3.000, 0.000).
B8 is a movement command to move from the P4 coordinate (3.000, 0.000) to -1.5mm in the X-axis direction and -2.598mm in the Y-axis direction, and finally moves to the P3 coordinate (1.500, -2.598). Chip B is cut off.
In the conventional method, all blocks are processed under the processing condition Eγ specified first in this way.

Next, a user operation during machining condition switching control mode machining in the present embodiment will be described with reference to FIG.
All user operations are performed on the operation board 4.
(S1) Open NC program creation screen and create machining NC program. (FIG. 3 is an example of the program)
(S2) Name and save the program created in S1.
(S3) Open the switch screen and turn on the “Machining condition switching control” switch.
(S4) Open the machining condition switching control parameter setting screen (FIG. 5). The distance (Lα) of the previous section, the condition number (Eα) used in the section, the distance (Lβ) of the rear section, and the conditions used in the section A number (Eβ) is set.
As shown in FIG. 8, this value is commonly used in all blocks. The value is stored in the data memory 15.
(S5) Open the program registration screen and register the program to be executed (the program saved in S2).
(S6) Press the start key on the operation board 4 to start the program and start machining.

Next, NC control in the machining condition switching control mode in the present embodiment will be described with reference to FIGS.
FIG. 6 is a flow showing the operation of the NC control apparatus 1 executing one NC program. When the start key is pressed on the operation board 4, the flow of FIG. 6 is started.
(S11) When the start key is pressed, the machining NC program analysis 19 program of the NC controller 1 is executed, the program is read from the machining NC program memory 9, and the program command for one block is analyzed.
(S12) If the analyzed block is a machining condition change command, the process proceeds to S13. If the analyzed block is not a machining condition change command, the process proceeds to S14.
(S13) If the machining condition change command is determined, the NC control device 1 takes note of the commanded machining condition number, reads the parameter of the condition from the data memory 15, and sends the value to the machining power source 3 and the flow rate control device 11. Command and move to S20.
(S14) If the analyzed block is a program movement command, go to S15. If not, move to S20.
(S15) When the movement command is determined, the movement amount calculation program 18 of the NC controller 1 calculates the movement amount of the current block.
Further, the current block movement distance is set in the current block remaining distance data, and the current block integrated distance is set to 0, and the process proceeds to S16.
(S16) The NC control device 1 further divides the moving amount of the current block according to the speed, and passes the moving amount to the axis control device at a predetermined cycle.
Therefore, the amount by which the axis is moved by the next cycle is calculated, and the process proceeds to S17.
(S17) As a result of the movement of the value obtained in S16 (assumed to be Lz) in the machining condition switching control program 21, it is determined whether the current block enters the Lα section, exits from the Lα section, or enters the Lβ section. If any one of the conditions is satisfied, it is not a machining condition change command, but a parameter value to be changed is commanded to the machining power source 3 and the flow rate control device 11 in order to switch the machining conditions.
Details will be described later with reference to FIG.
(S18) The movement amount obtained in S16 is sent to the axis controller 2 and the process proceeds to S19.
(S19) After a predetermined time has passed, it is checked whether or not the movement for one block has been completed. If completed, the process returns to S20, and if not, the process returns to S16.
(S20) If there is a next block in the machining NC program, return to S11. If not, end.

The sequence S17 described above is a characteristic part in the present embodiment, and will be described in detail with reference to FIG.
(S21) When the G number of the block analyzed in S11 is 1 or more and 3 or less, it is determined as a machining straight line or arc block, and the process proceeds to S22.
If other number, go to J1 end.
(S22) The movement amount (Lz) up to the next cycle obtained in S16 is added to the current block integrated distance, and Lz is subtracted from the current block remaining distance, and the process proceeds to S23.
(S23) It is checked whether or not the current block accumulated distance enters the section before the current block for the first time from 0 to Lα.

(S24) Since the current section of the current block (Lα) is entered, the electrical condition and flow rate of the machining power source are changed to the value of the machining parameter Eα set in S4 by the machining condition switching control mode. The parameter value is read from the data memory 15, and the parameter is commanded to the machining power source 3 and the flow rate control device 11 by the input / output circuit program 20.
Thereby, the electrical conditions and flow volume in the previous section (Lα) can be weakened.
For example, the side on the P1, P2 side of the cut-off point K1 of the chip A in FIG. 8 can be processed under weak conditions.
If commanded, move to J1 end.

(S25) It is checked whether the current block accumulated distance exceeds Lα for the first time, and if it exceeds for the first time, the process proceeds to S26, and if not, the process proceeds to S27.
(S26) Since the current block exits the previous block (Lα), the electrical conditions and flow rate are changed to the first specified machining condition parameters (condition parameters noted in S3).
The parameter value of the noted condition is read from the data memory 15, and the parameter is commanded to the machining power source 3 and the flow rate control device 11 by the input / output circuit program 20.
After the previous section (Lα), the electrical conditions and flow rate can be increased without worrying about the cut-off point. If commanded, move to J1 end.

(S27) It is checked whether the current block remaining distance has become smaller than Lβ for the first time.
(S28) Since the current post block block (Lβ) is entered, the electrical parameter and flow rate are changed to the Eβ machining parameter value set in S4 by the user in the machining condition switching control mode. The parameters are read from the memory 15 and commanded to the machining power source 3 and the flow rate control device 11 by the input / output circuit program 20.
Thereby, the electrical conditions and the flow rate in the rear section (Lα) can be weakened.
For example, the side on the P3-P1 side of the cut-off point K1 of the chip A in FIG. 8 can be processed under weak conditions.
If commanded, move to J1 end.

A machining locus in FIG. 8 shows the machining state of the above flow.
When the machining condition switching control switch is turned on and started, the block B1 is analyzed and changed to the machining parameters registered in the normal machining conditions (Eγ). 15, and the parameter value is output from the input / output circuit 16 to the machining power source 3 and the flow rate control device 11.
Since Eγ is used at a point other than the cut-off point, it specifies a parameter machining condition that can improve productivity.
Next, when the block B2 is executed, the NC control device 1 commands the machining liquid start, the wire feed, and the machining start finger to the machining power source 3 and the like.
When the B3 block is executed, the command system of the movement command that appears after this is set to the relative value system.
When the block B4 is executed, the NC controller 1 enters the section of the distance (Lα) set on the screen immediately after the movement from P1. The value is read from the data memory 15 and the parameter is output from the input / output circuit 16 to the machining power source 3 and the flow rate control device 11. (S24)

When moving to P2, the NC control device 1 calculates the current block integrated distance and the current block remaining distance each time a movement command is sent to the axis control device by the machining condition switching control program 21.
In order to switch to the parameter of the machining condition Eγ at the point P1 ′ where the block accumulated distance exceeds Lα, the NC controller 1 reads the parameter of Eγ from the data memory 15 and controls the machining power source 3 and the flow rate control from the input / output circuit 16. The parameter is output to the device 11. (S26)
Further, in order to switch the machining condition to the Eβ parameter at the P1 ″ point where the block remaining distance is less than Lβ, the NC controller 1 reads the Eβ parameter from the data memory 15 and the machining power source 3 from the input / output circuit 16. The parameter is output to the flow rate control device 11. (S28)
Similarly to the B4 block, the NC control device 1 passes the command to the machining power source 3 and the flow rate control device 11 so that the next block B5 becomes the parameters of Eα, Eγ, and Eβ depending on the current block position.
By repeating the same process for all blocks, the cut-off part can be processed under weak conditions without editing the program even if cut-off points are scattered.

According to the present embodiment, the user activates the machining condition switching control mode without creating a complicated machining program, and specifies the head portion and the end portion of the block for switching the machining conditions, and the machining conditions at that location. By designating, it is possible to easily create a program capable of processing a portion that becomes a cut-off portion under a weak condition and processing a portion that does not become a cut-off portion under a strong condition.
For example, when a large number of chips are cut out from a single sintered disk by a one-stroke NC program, if the total length of one piece is 3 mm, the front and rear sections are combined to be about 0.6 mm, and this section is weak. It is possible to process under the conditions, and the remaining 80% of the section can be processed under strong conditions, so that the processing time per chip can be shortened without chipping, and the productivity of the chip is improved.
Further, even in a portion where the conventional corner control function cannot be used, the corner portion can be processed under weak conditions.

In order to realize the same thing without using the mode shown in this embodiment, it is necessary to create a program in which one block is divided into three blocks. This program is shown in FIG. is there.
In FIG. 9, the moving blocks of B4 and B5 in FIG. 3 are divided into blocks having a front section of 0.3 mm and a rear section of 0.3 mm.
Specifically, the moving block of B4 is divided into three parts B10, B12, and B14, and processing condition change commands Eα (B9), Eγ (B11), which are privately used before each movement code, It is necessary to insert Eβ (B13).
Therefore, 2 blocks (B4, B5) become 12 blocks, and it takes a lot of time to create a one-stroke writing program. However, in this embodiment, it is not necessary to create such a complicated program.

Embodiment 2. FIG.
In the first embodiment, the distances (Lα, Lβ) of the previous and subsequent sections used in the control on the machining condition switching control parameter setting screen of the operation board unit 4 and the machining condition numbers (Eα, Eβ) is set, but this parameter can be changed by a program.
Specifically, the machining condition switching control parameter change G code is separately provided, and when this machining condition switching control parameter change G code is detected in the NC program, this can be realized by changing the parameters.
The machining condition switching control parameters Lα, Lβ, Eα, Eβ are commanded by arguments.

If the machining condition switching control parameter change code is “M150”, the following designation is made.
M150 X0.3 Y0.3 I1 J2;
Here, argument X: previous section distance, argument Y: rear section distance, argument I: previous section machining condition number, argument J: rear section machining condition number may be used.
In the above case, the front section 0.3 mm, the rear section 0.3 mm, the front section machining condition number is set to 1, and the rear section machining condition number is set to 2.

The machining condition switching control parameter change by the program is set to the data stored when the NC control device 1 determines that the machining condition switching control parameter is a machining condition switching control parameter by program analysis, when the parameter value is input from the machining condition switching control screen.
Therefore, after changing the machining condition switching control parameter, the operation is performed with the changed value.
As shown in FIG. 10, when plates of different materials are prepared on the surface plate and processed continuously, assuming that the optimum values of the processing condition switching control parameters are different because of different materials, the processing of the sintered material A is performed. Before moving to the processing of the final sintered material B, it is necessary for a person to change the value on the parameter setting screen.
However, if the parameter value can be changed by a program as shown in FIG. 11, it is not necessary to perform the troublesome work of waiting for the waiting person to change the parameter value from the screen until the processing of the sintered material A is completed.

It is a block diagram which shows the structure of a wire electric discharge machine. 2 is a block diagram showing a configuration of an NC control device 1. FIG. It is a figure which shows NC program for a process. It is a flow chart which shows user operation at the time of processing condition change control mode processing. It is a figure which shows the process condition switching control parameter setting screen. It is a flowchart showing operation | movement of the NC control apparatus which performs NC program. It is a flowchart which shows the detail of a process condition switching process. It is a figure which shows the processing content of a chip | tip. It is a figure which shows the conventional NC program for a process for implement | achieving block division. It is a figure which shows the example which processes continuously the plate of a different material. It is a figure which shows the example which changes a parameter value with a program. It is a figure which shows the example of a process.

Claims (4)

A machining NC program memory for storing machining NC programs composed of a plurality of blocks created by a user;
An NC program analyzing unit for analyzing the machining NC program for each block and giving a command to a control means connected via an input / output circuit;
NC controller for wire electrical discharge machining that performs wire electrical discharge machining using the machining NC program,
As a result of the analysis by the NC program analysis unit, when the block program is a movement command at the time of machining, the movement amount in the block is calculated, and the machining conditions of the specified distance portion from the first point and the last point in the block are calculated. Is equipped with a machining condition switching control unit that performs control for switching to machining conditions for cutting points defined separately in all blocks of the NC program, and performs cutting of multiple chips using the first point and the last point as the cutting points. NC numerical control device for wire electrical discharge machining. After the machining NC program is stored, a machining condition switching control switch is provided which designates the machining NC program and allows the user to input a predetermined distance and a separately defined machining condition, and activates the switch. The NC control apparatus for wire electric discharge machining according to claim 1, wherein the distance and machining conditions are set at times. The wire electric discharge machining NC control device according to claim 2 , wherein the distance and machining conditions are set as a set of parameters, and a plurality of sets of parameters are set in a block of the machining NC program. When analyzing the machining condition switching control parameter change code in the machining NC program, the NC program analysis unit analyzes the machining NC program after analysis at the distance and machining conditions specified by the machining condition switching control parameter change code. The NC control apparatus for wire electric discharge machining according to any one of claims 1 to 3 , wherein the machining condition switching control is performed.

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