Numerical control device

Abstract

The numerical control device of the present invention receives input of the action modes of multiple tools and the action conditions of the action modes, calculates movement instruction data containing speed information and position information of the multiple tools based on the input action modes and action conditions, makes the cutting paths of the multiple tools intersect, generates interpolation data based on the movement instruction data, and controls the motor of the driving machine based on the interpolation data.

Description

Technical Field

[0001] The present invention relates to a numerical control device, and more particularly to a numerical control device capable of performing thread cutting processing by cooperating with a plurality of tools. Background Art

[0002] When threading a workpiece, the workpiece is rotated while the tool is moved relative to the workpiece axial direction, applying a predetermined depth to the tool. While some processes involve moving a single tool relative to the workpiece's rotation, most often a machine tool with multiple axes is used, allowing multiple tools to move in coordination relative to the workpiece to perform thread cutting.

[0003] In conventional thread cutting and turning, the tool continuously penetrates the workpiece in one direction. Consequently, chips generated during machining are not cut off but continue to be generated as the tool moves. Continuing machining without removing the chips can lead to problems such as chips wrapping around the tool or chips contacting and damaging the workpiece. These issues have been addressed through various methods.

[0004] As public documents of technologies that solve the problems in this way, International Publication No. 2016 / 056526 and Japanese Patent Application Laid-Open No. 2019-185780 can be cited. Summary of the Invention

[0005] Problems to be solved by the invention

[0006] During the machining process, the chips can be cut by applying a swinging motion to the movement of the tool. However, the mechanical load of the swinging motion is large, so there is a problem of adversely affecting the mechanical life (ball screw, bearings, etc.) and tool life. In addition, if a processing step for cutting chips is added, there is also the problem of longer machining time compared to conventional thread cutting. Moreover, if the machining time is to be the same as that of conventional thread cutting, the motor speed needs to be increased, and high-load machining is required compared to conventional thread cutting. Another problem is that the life of the tool blade tends to be shortened.

[0007] Therefore, a technology for cutting chips generated by cutting without increasing machining time or affecting the life of the machine and tool is desired.

[0008] Means for solving problems

[0009] The numerical controller of the present invention solves the above-mentioned problem by performing thread cutting while controlling the relative speed and position between the multiple tools in order to break chips in a machining method in which cutting is performed by a machine having a structure capable of simultaneously controlling multiple tools.

[0010] Furthermore, the numerical control device of the present invention controls the thread cutting processing of a workpiece performed by a machine equipped with multiple tools based on a program, and comprises: a chip breaking information input unit that receives input of the action mode of the multiple tools and the action conditions of the action mode; a multiple tool action calculation unit that calculates movement instruction data including speed information and position information of the multiple tools based on the action mode and action conditions input by the chip breaking information input unit so that the cutting paths of the multiple tools intersect; an interpolation unit that generates interpolation data based on the movement instruction data; and a servo control unit that controls the motor that drives the machine based on the interpolation data.

[0011] Effects of the Invention

[0012] According to the present invention, thread cutting can be performed while cutting chips generated by cutting without increasing the machining time or affecting the machine life and tool life. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic hardware configuration diagram of a numerical controller according to one embodiment of the present invention.

[0014] Figure 2 This is a schematic functional block diagram of a numerical controller according to one embodiment of the present invention.

[0015] Figure 3 This is a first diagram illustrating workpiece machining using a first tool mounted on a first tool post and a second tool mounted on a second tool post in a tool front insertion method that can be calculated using an embodiment of the present invention.

[0016] Figure 4 This is a second diagram illustrating workpiece machining using a first tool and a second tool in a tool front insertion method.

[0017] Figure 5 The third diagram explains workpiece processing using the first tool and the second tool in the tool front insertion method.

[0018] Figure 6 The fourth diagram explains workpiece processing using the first tool and the second tool in the tool front insertion method.

[0019] Figure 7 The fifth diagram illustrates workpiece processing using the first tool and the second tool in a tool front insertion method.

[0020] Figure 8The sixth diagram explains workpiece processing using the first tool and the second tool in the tool front insertion method.

[0021] Figure 9 This is a first diagram illustrating workpiece machining using a first tool mounted on a first tool post and a second tool mounted on a second tool post, in which a tool vibration pattern that can be calculated using an embodiment of the present invention is described.

[0022] Figure 10 This is a second diagram illustrating workpiece machining using a first tool and a second tool in a tool vibration method.

[0023] Figure 11 The third diagram explains workpiece machining using the first tool and the second tool in a tool vibration method.

[0024] Figure 12 This is a first diagram illustrating workpiece machining using a first tool mounted on a first tool post and a second tool mounted on a second tool post in a tool rear insertion method that can be calculated using an embodiment of the present invention.

[0025] Figure 13 This is a second diagram illustrating workpiece machining using the first tool and the second tool in a tool rear insertion method.

[0026] Figure 14 The third diagram explains workpiece machining using the first tool and the second tool in the tool rear insertion method.

[0027] Figure 15 The fourth diagram explains workpiece machining using the first tool and the second tool in the tool rear insertion method.

[0028] Figure 16 This is a first diagram illustrating workpiece machining using a first tool mounted on a first tool post and a second tool mounted on a second tool post using a combination method that can be calculated according to an embodiment of the present invention.

[0029] Figure 17 This is a second diagram illustrating workpiece processing using a first tool and a second tool in combination.

[0030] Figure 18 The third diagram explains workpiece processing using the first tool and the second tool in combination.

[0031] Figure 19 The fourth diagram explains workpiece processing using the first tool and the second tool in combination.

[0032] Figure 20The fifth diagram explains workpiece processing using a first tool and a second tool in combination. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0034] Figure 1 This is a schematic hardware configuration diagram showing the main parts of a numerical controller according to one embodiment of the present invention. For example, the numerical controller 1 of the present invention can be implemented as a numerical controller that controls a lathe based on a program.

[0035] The numerical controller 1 of this embodiment includes a CPU (Central Processing Unit) 11, which is a processor that controls the entire numerical controller 1. The numerical controller 1 of this embodiment also includes a ROM (Read Only Memory) 12 and a RAM (Random Access Memory) 13. In this configuration, the CPU 11 reads the system program stored in the ROM 12 via a bus 20 and controls the entire numerical controller 1 according to the system program. The RAM 13 temporarily stores various data. Examples of data that can be temporarily stored in the RAM 13 include temporary calculation data, display data, and various data input from the external device.

[0036] The numerical controller 1 of this embodiment further includes a nonvolatile memory 14. The nonvolatile memory 14 can be composed of a battery-backed memory (not shown), an SSD (Solid State Drive), or other devices. This configuration allows the stored data to be maintained even when the power to the numerical controller 1 is turned off. The nonvolatile memory 14 stores programs read from an external device 72 via the interface 15 and programs input via the display / MDI unit 70. The programs and various data stored in the nonvolatile memory 14 can be expanded into the RAM 13 when being executed or used. Furthermore, various system programs, such as well-known analysis programs, are pre-written in the ROM 12.

[0037] The numerical controller 1 of this embodiment further includes an interface 15 for connecting the CPU 11 of the numerical controller 1 to an external device 72, such as a USB device. Programs and various parameters used to control the lathe are read from the external device 72. Furthermore, programs and various parameters edited within the numerical controller 1 can be stored in an external storage unit via the external device 72. The numerical controller 1 of this embodiment further includes a PMC (Programmable Machine Controller) 16 and an input / output unit (I / O unit) 17. The PMC 16 controls the lathe and its peripheral devices by outputting signals via the I / O unit 17 based on a sequence program built into the numerical controller 1. Examples of lathe peripheral devices include tool changers, actuators such as robots, and sensors installed on the lathe. Furthermore, the PMC 16 receives signals from various switches on the operating panel of the lathe and peripheral devices, and transmits them to the CPU 11 after performing necessary signal processing.

[0038] The display / MDI unit 70 is a manual data input device equipped with a display, keyboard, etc. Interface 18 receives commands and data from the keyboard of the display / MDI unit 70 and transmits them to the CPU 11. The numerical controller 1 also includes an interface 19 for connecting to an operation panel 71 equipped with a manual pulse generator, etc., which is used when manually driving each axis.

[0039] The numerical control device 1 of this embodiment also has an axis control circuit 30 for controlling the axis of the lathe, and a servo amplifier 40 connected to the axis control circuit 30. In addition, the servo amplifier 40 is also connected to a servo motor 50 that moves the axis of the lathe. The axis control circuit 30 receives the axis movement instruction amount from the CPU 11, and outputs the axis instruction to the servo amplifier 40. The servo amplifier 40 receives the instruction and drives the servo motor 50. The servo motor 50 of the axis has a built-in position / speed detector. The position / speed feedback signal from the position / speed detector is fed back to the axis control circuit 30 to perform position / speed feedback control. Figure 1 In the hardware structure diagram of FIG, the axis control circuit 30, the servo amplifier 40, and the servo motor 50 are shown as one each, but in reality, they are prepared according to the number of axes of the lathe to be controlled. Figures 3 to 20 As in the embodiment of the present invention of the action example shown, when controlling a lathe having two tool holders, two sets of axis control circuits 30, servo amplifiers 40, and servo motors 50 are prepared for driving a first tool holder mounted with a first tool in the X-axis and Z-axis directions, respectively, and two sets of axis control circuits 30, servo amplifiers 40, and servo motors 50 are prepared for driving a second tool holder mounted with a second tool in the X-axis and Z-axis directions, respectively.

[0040] The numerical controller 1 of this embodiment further includes a spindle control circuit 60 and a spindle amplifier 61 connected to the spindle control circuit. The spindle amplifier 61 is also connected to a spindle motor 62 of a lathe. The spindle control circuit 60 receives a spindle rotation command and outputs a spindle speed signal to the spindle amplifier 61. The spindle amplifier 61 receives this spindle speed signal and rotates the spindle motor 62 of the lathe at the commanded speed, thereby driving the workpiece. A position encoder 63 is integrated into the spindle motor 62. The position encoder 63 outputs feedback pulses in synchronization with the rotation of the spindle, and the CPU 11 reads these feedback pulses via the spindle control circuit 60.

[0041] Figure 2 This is a schematic functional block diagram of a numerical controller 1 according to an embodiment of the present invention.

[0042] By Figure 1 The CPU 11 of the numerical control device 1 shown in the figure executes the system program to control the operation of each part of the numerical control device 1, thereby achieving Figure 2 The numerical controller 1 of the present embodiment controls a lathe that drives a first tool post mounted with a first tool and a second tool post mounted with a second tool to machine a workpiece mounted on a spindle.

[0043] The numerical controller 1 of this embodiment includes an analysis unit 100, an information input unit 102, more specifically, a chip breakage information input unit 102 that inputs information related to chip breakage, and a motion calculation unit 104, more specifically, a multiple tool motion calculation unit 104 that performs calculations related to the motions of multiple tools. Furthermore, the numerical controller 1 of this embodiment includes a first interpolation unit 122, a second interpolation unit 124, servo control units 130x1, 130z1, 130x2, and 130z2, and a spindle control unit 140. Furthermore, the nonvolatile memory 14 of the numerical controller 1 pre-stores a program 200 for executing control for driving tools mounted on two tool holders to machine a workpiece.

[0044] By Figure 1The numerical controller 1 shown in FIG. 1 is provided with a CPU 11 that executes a system program read from a ROM 12. The CPU 11 primarily performs computational processing using the RAM 13 and nonvolatile memory 14, thereby implementing the analysis unit 100. The analysis unit 100 reads and analyzes program blocks of a program 200 to generate movement command data for the servo motors driving the first and second tool rests, and spindle command data for commanding the spindle speed. Based on the feed command indicated by the program blocks of the program 200, the analysis unit 100 generates movement command data for the servo motors 50x1 and 50z1 driving the first tool rest, and movement command data for the servo motors 50x2 and 50z2 driving the second tool rest. Furthermore, the analysis unit 100 generates spindle command data based on the spindle rotation command indicated by the program blocks of the program 200.

[0045] By Figure 1 The CPU 11 of the numerical control device 1 shown executes the system program read from the ROM 12. The CPU 11 mainly uses the RAM 13 and the non-volatile memory 14 for calculation processing, and uses the interface 18 and the display / MDI unit 70 for input and output processing, thereby realizing the chip breaking information input unit 102. The chip breaking information input unit 102 displays a setting screen to the operator via the display / MDI unit 70, allowing the operator to input the operation mode of the first tool holder and the second tool holder and the conditions required for the operation. The chip breaking information input unit 102 allows the operator to select the operation mode described later, such as (1) tool front insertion mode, (2) tool vibration mode, (3) tool rear insertion mode, and (4) combination mode. In addition, the chip breaking information input unit 102 allows the operator to set the chip breaking length (so-called chip length). The chip length can be set by specifying the lead count or specifying the coordinate value. The information input through the chip breaking information input unit 102 is output to the plurality of tool operation calculation units 104.

[0046] By Figure 1The CPU 11 included in the numerical controller 1 shown executes a system program read from the ROM 12. The CPU 11 primarily performs computational processing using the RAM 13 and non-volatile memory 14, thereby implementing a plurality of tool motion calculation units 104. Based on the movement command data generated by the analysis unit 100, the plurality of tool motion calculation units 104 calculate the movement of each tool in accordance with the information input from the chip breaking information input unit 102. Examples of information input from the chip breaking information input unit 102 include the selected movement mode and chip length, but these are not limited to these examples; various types of information can be input. The plurality of tool motion calculation units 104 calculates the movement of each tool by calculating the speed and position of each tool so that its respective cutting paths intersect. The movement of each tool calculated by the plurality of tool motion calculation units 104 is the movement of breaking the chips generated during machining by each tool using the chip length input from the chip breaking information input unit 102. The movement of each tool calculated by the plurality of tool motion calculation units 104 is output as movement command data to the first interpolation unit 122 and the second interpolation unit 124. The motion of each tool calculated by the plurality of tool motion calculation units 104 will be described later.

[0047] By Figure 1 The CPU 11 included in the numerical controller 1 shown executes a system program read from the ROM 12 . The CPU 11 mainly performs calculations using the RAM 13 and the nonvolatile memory 14 , thereby realizing the first interpolation unit 122 and the second interpolation unit 124 .

[0048] Based on the movement command data generated by the analysis unit 100, the first interpolation unit 122 generates interpolated data by interpolating points on the command path of the first tool mounted on the first tool post, as specified by the movement command data, at an interpolation cycle (so-called control cycle). Furthermore, based on the movement command data generated by the analysis unit 100, the second interpolation unit 124 generates interpolated data by interpolating points on the command path of the second tool mounted on the second tool post, as specified by the movement command data, at an interpolation cycle. Interpolation processing by the first and second interpolation units 122 and 124 is performed at each interpolation cycle.

[0049] By Figure 1The numerical controller 1 shown in the figure has a CPU 11 that executes a system program read from a ROM 12. The CPU 11 primarily performs computations using the RAM 13 and nonvolatile memory 14. Furthermore, the axis control circuit 30 and the servo amplifier 40 control the servo motor 50, thereby implementing servo control units 130x1 and 130z1. Based on interpolation data generated by the first interpolation unit 122, the servo control units 130x1 and 130z1 control the servo motor 50x1 that drives the first tool post in the X-axis direction and the servo motor 50z1 that drives the first tool post in the Z-axis direction, respectively, thereby driving the first tool post of the controlled machine.

[0050] In addition, through Figure 1 The CPU 11 included in the numerical controller 1 shown executes a system program read from the ROM 12. The CPU 11 primarily performs computations using the RAM 13 and nonvolatile memory 14. Furthermore, the axis control circuit 30 and the servo amplifier 40 control the servo motor 50, thereby implementing servo control units 130x2 and 130z2. The servo control units 130x2 and 130z2 control the servo motors 50x2 and 50z2, respectively, for driving the second tool post in the X-axis direction and the Z-axis direction, based on interpolation data generated by the second interpolation unit 124, thereby driving the second tool post of the controlled machine.

[0051] By Figure 1 The numerical controller 1 shown has a CPU 11 that executes a system program read from a ROM 12. The CPU 11 primarily performs calculations using a RAM 13 and a nonvolatile memory 14. Furthermore, a spindle control circuit 60 and a spindle amplifier 61 control a spindle motor 62, thereby implementing a spindle control unit 140. The spindle control unit 140 controls the spindle motor 62 for rotating the spindle of the controlled machine based on spindle command data generated by the analysis unit 100.

[0052] Several examples of the motions of the respective tools calculated by the plurality of tool motion calculation units 104 provided in the embodiment of the present invention are shown below.

[0053] Figures 3 to 8 This is a series of diagrams showing the processing conditions of a workpiece 7 using a first tool 5 mounted on a first tool holder 3 and a second tool 6 mounted on a second tool holder 4 in (1) the tool front insertion method calculated by the plurality of tool motion calculation units 104.

[0054] In the tool front loading mode, the thread cutting process is initially started with any tool. Figure 3In the illustrated state, a first tool 5 mounted on a first tool rest 3 is cutting (i.e., threading) a workpiece 7 mounted on a main spindle 2 and rotating. Meanwhile, a second tool 6 mounted on a second tool rest is moving in the Z-axis direction at a speed exceeding that of the first tool 5, while not cutting, from an X-axis position where it does not contact the workpiece 7. In this state, chips 8 are generated from the threading position of the first tool 5.

[0055] Then, if Figure 4 As shown, during the process of first tool 5 cutting workpiece 7, when second tool 6 reaches the cutting start point, which is located half a spindle rotation as viewed from first tool 5, second tool rest 4 changes its Z-axis movement speed to the cutting speed and then moves in the X-axis direction, thereby starting cutting of workpiece 7 by second tool 6. The cutting start point of second tool 6 is a position where the cutting length from the position where first tool 5 started cutting is approximately the same as the chip length input by chip breaking information input unit 102. At this stage, workpiece 7 is being machined by both first tool 5 and second tool 6.

[0056] Afterwards, if Figure 5 As shown, when the first tool 5 reaches the cutting start point of the second tool 6, the chips generated by the cutting of the first tool 5 are broken by the cutting groove of the second tool 6. When the cutting point of the first tool 5 reaches the cutting start point of the second tool 6, the first tool holder 3 moves in the X-axis direction, and the first tool 5 enters a non-cutting state.

[0057] When the first tool 5 becomes a non-cutting state, as shown in FIG. Figure 6 As shown in FIG, the first tool holder 3 moves in the Z-axis direction at a speed exceeding the second tool 6 in a non-cutting state. And, when the first tool 5 reaches the cutting start point after the spindle rotates half a circle as viewed from the second tool 6, as shown in FIG. Figure 7 As shown, after the first tool rest 3 has set its Z-axis movement speed to the cutting speed, it moves in the X-axis direction, and begins cutting with the first tool 5. The cutting start point of the first tool 5 is a position where the cutting length from the position where the second tool 6 starts cutting is substantially the same as the chip length input by the chip breaking information input unit 102. At this stage, the workpiece 7 is again being machined by both the first tool 5 and the second tool 6.

[0058] Afterwards, if Figure 8 As shown, when the second tool 6 reaches the cutting start point of the first tool 5, the chips generated by the cutting of the second tool 6 are broken by the cutting groove of the first tool 5. When the cutting point of the second tool 6 reaches the cutting start point of the first tool 5, the second tool holder 4 moves in the X-axis direction, and the second tool 6 enters a non-cutting state.

[0059] In this way, the tool is placed in front of the Figures 3 to 8In the action shown, the first tool 5 and the second tool 6 alternately process the workpiece 7. In this action mode, the chips generated by the cutting of the first tool 5 are broken by the cutting groove of the second tool 6. In addition, the chips generated by the cutting of the second tool 6 are broken by the cutting groove of the first tool 5. By making the movement speed of the first tool holder 3 and the second tool holder 4 in the Z-axis direction when processing the workpiece 7 the cutting feed speed instructed by program 200, the processing time is roughly the same as that of normal thread cutting (strictly speaking, the processing time is slightly shorter due to the degree of forward insertion). In addition, since there is no need for swinging or similar actions, no large load is imposed on the lathe and each tool. Moreover, since the workpiece 7 is processed alternately by the first tool 5 and the second tool 6, the processing load can be distributed to each tool. For example, since the non-cutting time of the tool is longer than in the case of continuous processing, if this method is used, the heat generated during processing can be fully removed, and the tool life can also be extended.

[0060] Figures 9-11 This is a series of diagrams showing the conditions of machining a workpiece 7 using a first tool 5 mounted on a first tool holder 3 and a second tool 6 mounted on a second tool holder 4 in (2) tool vibration modes calculated by a plurality of tool motion calculation units 104 .

[0061] In the tool vibration method, one tool becomes the main body and performs thread cutting. Figure 9 In the illustrated state, a workpiece 7 mounted on a main spindle 2 and rotating is being cut (threaded) using a first tool 5 mounted on a first tool rest 3. At this time, a second tool 6 mounted on a second tool rest is moving in the Z-axis direction at a speed exceeding that of the first tool 5, while not cutting, from an X-axis position where it does not contact the workpiece 7. In this state, chips 8 are generated from the thread cutting position of the first tool 5.

[0062] Then, if Figure 10 As shown, during cutting by the first tool 5, when the second tool 6 reaches the cutting start point, which is located half a spindle rotation from the perspective of the first tool 5, the second tool rest 4 changes its Z-axis speed to the cutting speed and then moves in the X-axis direction to perform cutting by the second tool 6. The cutting start point of the second tool 6 is a position where the cutting length from the point where the first tool 5 started cutting is approximately the same as the chip length input by the chip breaking information input unit 102. At this stage, the workpiece 7 is being machined by both the first tool 5 and the second tool 6.

[0063] Afterwards, if Figure 11As shown, the second tool rest 4 moves in the X-axis direction, and the second tool 6 becomes non-cutting again. When the first tool 5 reaches the cutting starting point of the second tool 6, the chips generated by the cutting of the first tool 5 are broken by the cutting groove of the second tool 6.

[0064] Thus, in the tool vibration mode, by repeatedly Figures 9 to 11 The actions shown are as follows: the first tool 5 processes the workpiece 7 and the second tool 6 breaks the chips. By setting the movement speed of the first tool rest 3 in the Z-axis direction when processing the workpiece 7 to the cutting feed speed instructed by program 200, the processing time of the workpiece 7 is made the same as that of a normal thread cutting process. Since the chip cutting action of the second tool 6 is performed within the normal tool rest movement range, no large load is applied to the lathe and the various tools. In addition, by using a vibration-resistant tool as the second tool 6, the load on the entire machine can also be reduced. In the above example, the structure is such that cutting is continuously performed only by the first tool 5, and the second tool 6 temporarily enters the cutting point, but the functions of the first tool 5 and the second tool 6 can also be reversed. In addition, by switching the functions of the first tool 5 and the second tool 6 at the timing when the load on the tool has accumulated, the load can be distributed to each tool.

[0065] Figures 12 to 15 The figure shows the processing status of the workpiece 7 using the first tool 5 mounted on the first tool post 3 and the second tool 6 mounted on the second tool post 4 in the (3) tool rear insertion method calculated by the plurality of tool motion calculation units 104.

[0066] In the tool rear insertion mode, initially start the thread cutting process with any tool. Figure 12 In the illustrated state, a workpiece 7 mounted on a main spindle 2 and rotating is being cut (threaded) by a first tool 5 mounted on a first tool post 3. At this time, a second tool 6 mounted on a second tool post is moving in the Z-axis direction behind the first tool 5 at an X-axis position, not in contact with the workpiece 7, without cutting. In this state, chips 8 are generated from the thread cutting position of the first tool 5.

[0067] Then, if Figure 13 As shown, when the second tool 6 reaches the cutting start point, the first tool rest 3 moves in the X-axis direction, and the first tool 5 enters a non-cutting state. Then, before the workpiece 7 rotates half a turn, the second tool rest 4, after adjusting its Z-axis movement speed to the cutting speed, moves in the X-axis direction, inserting the second tool 6 into the cut groove cut by the first tool 5. Then, when the workpiece 7 has rotated half a turn, cutting by the second tool 6 resumes from the point where cutting by the first tool 5 was interrupted.

[0068] The chips generated by cutting with the first tool 5 are broken when the first tool 5 retreats. The cutting start point of the second tool 6 is a position where the cutting length from the position where the first tool 5 starts cutting is substantially the same as the chip length input by the chip breaking information input unit 102 .

[0069] When the first tool 5 becomes a non-cutting state, as shown in FIG. Figure 14 As shown in FIG. 1 , the first tool rest 3 moves in the Z-axis direction while adjusting the speed. Then, when the first tool 5 arrives at the next cutting starting point, as shown in FIG. Figure 15 As shown, the second tool rest 4 moves in the X-axis direction, and the second tool 6 enters a non-cutting state. Then, before the workpiece 7 rotates half a turn, the first tool rest 3, after changing the Z-axis movement speed to the cutting speed, moves in the X-axis direction, inserting the first tool 5 into the cut groove cut by the second tool 6. Then, when the workpiece 7 has rotated half a turn, cutting by the first tool 5 resumes from the point where cutting by the second tool 6 was interrupted. The chips generated by cutting by the second tool 6 are broken as the second tool 6 retreats. The cutting start point of the first tool 5 is a position where the cutting length from the point where cutting by the second tool 6 was started is approximately the same as the chip length input by the chip breaking information input unit 102.

[0070] In this way, the tool is placed in the back and repeated Figures 12 to 15 In the illustrated operation, the first tool 5 and the second tool 6 alternately machine the workpiece 7. In this operation, the chips generated by the cutting of the first tool 5 are cut off as the first tool 5 retreats. Furthermore, the chips generated by the cutting of the second tool 6 are cut off as the second tool 6 retreats. By setting the Z-axis movement speed of the first tool rest 3 and the second tool rest 4 during machining of the workpiece 7 to the cutting feed rate specified in program 200 and the like, the machining time of the workpiece 7 is substantially the same as that of a normal thread cutting operation.

[0071] Furthermore, since no swinging motion is required, significant loads are not placed on the lathe or the tools. Furthermore, since the workpiece 7 is processed alternately by the first and second tools, the processing load can be distributed across the tools. For example, compared to continuous processing, the tool's non-cutting time is extended, effectively dissipating heat during processing and potentially extending the tool's lifespan. Furthermore, since the tool is not used for processing in the cutting direction (radial direction of the workpiece), the load on the tool is particularly reduced.

[0072] Figures 16 to 20The figure shows the processing status of the workpiece 7 using the first tool 5 mounted on the first tool holder 3 and the second tool 6 mounted on the second tool holder 4 using the (4) combination method calculated by the plurality of tool motion calculation units 104. The combination method is a method in which the tool motions of the (1) front tool placement method and the (3) rear tool placement method are combined.

[0073] In combination, such as Figure 16 As shown, the thread cutting process is started by both the first tool 5 and the second tool 6. Figure 16 The first tool 5 is arranged so that the cutting position is located ahead of the second tool 6 in the Z-axis direction. The first tool 5 and the second tool 6 are respectively arranged so that their cutting lengths are substantially the same as the chip length input by the chip breaking information input unit 102.

[0074] At the moment when the cutting position of the second tool 6 reaches the cutting start position of the first tool 5, as shown in FIG. Figure 17 As shown, the first tool rest 3 and the second tool rest 4 are moved in the X-axis direction, and the first tool 5 and the second tool 6 are in a non-cutting state. At this moment, the chips 8 generated during cutting by the first tool 5 and the second tool 6 are broken.

[0075] Afterwards, if Figure 18 As shown, while maintaining the relative front-back relationship between the first tool 5 and the second tool 6, the second tool 6 is moved to the cutting end point of the first tool 5. Then, at their respective positions, the first tool holder 3 and the second tool holder 4 are moved in the X-axis direction to start cutting the first tool 5 and the second tool 6 (refer to Figure 19 ).

[0076] Then, at the moment when the cutting position of the second tool 6 reaches the cutting start position of the first tool 5, as shown in FIG. Figure 20 As shown, the first tool rest 3 and the second tool rest 4 are moved in the X-axis direction, and the first tool 5 and the second tool 6 are in a non-cutting state. At this moment, the chips 8 generated during cutting by the first tool 5 and the second tool 6 are broken.

[0077] Thus, in the combination mode, by repeatedly Figures 16 to 20In the illustrated operation, the first tool 5 and the second tool 6 each process the workpiece 7. In this operation mode, the chips generated by the cutting of the first tool 5 are broken as the first tool 5 retreats. Furthermore, the chips generated by the cutting of the second tool 6 are broken by the cutting grooves of the first tool 5. Even considering the movement time of the tool in the non-cutting state (i.e., the rapid forward time), the time associated with machining the workpiece 7 is significantly shorter than when machining using a single tool. In particular, if the cutting distance in a single cut is long, machining can be performed efficiently. By setting the cutting feed rate to that instructed by the thread cutting program 200, etc., the machining time is approximately halved compared to that of conventional thread cutting. In addition, since swinging motions are not required, a large load is not imposed on the lathe and the tools. Moreover, since machining of the workpiece 7 is divided between the first and second tools, the machining load can be distributed to each tool. Furthermore, according to this method, heat generated during machining can be sufficiently removed during the tool's non-cutting time, and the tool life can be extended.

[0078] An embodiment of the present invention has been described above together with several tool operation examples. However, the present invention is not limited to the above-described embodiment and operation examples, and can be implemented in various forms by adding appropriate modifications.

[0079] For example, in the exemplary configuration and operation examples of the above-described embodiment, the numerical controller 1 is described as controlling a machine structure in which the first tool rest 3 and the second tool rest 4 are positioned opposite each other. However, as long as the first tool 5 and the second tool 6 are positioned so that they can effectively perform thread cutting, the tool rests and tools can be arranged in any manner.

[0080] Furthermore, in the exemplary configuration and operation examples of the above embodiment, the numerical controller 1 is described as controlling a machine configured to perform thread cutting using two tool holders and two tools. However, a configuration in which three or more tool holders and three or more tools are used for thread cutting may also be employed. In this case, the multiple tool motion calculation unit 104 of the numerical controller 1 generates movement command data for each tool so that the cutting paths of the tools intersect.

[0081] Furthermore, in the exemplary configuration and operation examples of the above embodiment, a machine having a structure for thread cutting using two movable tool holders is described as the control target of the numerical controller 1. However, regardless of this description, a structure can also be configured to perform thread cutting using one movable tool holder, one fixed tool holder, and one movable spindle table. In this case, the multiple tool motion calculation unit 104 generates movement command data for each tool so that the cutting paths of the respective tools intersect. In this case, the number of tool holders used for thread cutting can naturally be three or more.

Claims

1. A numerical control device that controls a thread cutting process of a workpiece by a machine equipped with a plurality of tools based on a program, characterized in that: The numerical control device comprises: a chip breaking information input unit for receiving input of operation modes of the plurality of tools and operation conditions of the operation modes; a plurality of tool motion calculation units for calculating movement instruction data including speed information and position information of the plurality of tools based on the motion mode and motion conditions inputted through the chip breaking information input unit so as to cause the respective cutting paths of the plurality of tools to intersect; an interpolation unit that generates interpolation data based on the movement instruction data; as well as a servo control unit that controls a motor that drives the machine based on the interpolation data, The chip breaking information input unit receives input of the operation conditions including the chip breaking length. The position information of the multiple tools calculated by the multiple tool motion calculation units includes a cutting start point, and the cutting start point of one of the multiple tools is a position where the cutting length from the position where cutting of other tools is started is approximately the same as the chip breaking length.

2. The numerical control device according to claim 1, wherein The movement instruction data calculated by the plurality of tool motion calculation units are data related to movement instructions for repeatedly performing the following motions between the plurality of tools: Among them, this action is relative to the cutting tool among the multiple tools, and other tools different from the cutting tool enter the cutting starting point before the uncutting path of the cutting tool, and continue to cut after the chips are broken by the cutting tool.

3. The numerical control device according to claim 1, wherein The movement instruction data calculated by the multiple tool motion calculation units is data related to the following movement instruction, wherein, during the process of cutting by a first tool, a second tool different from the first tool enters the cutting start point before the uncutting path of the first tool, and the chips are broken by the first tool.

4. The numerical control device according to claim 1, wherein The movement instruction data calculated by the plurality of tool motion calculation units are data related to movement instructions for repeatedly performing the following motions between the plurality of tools: Among them, the action is to cut by the cutting tool among the multiple tools. After the cutting is interrupted, other tools different from the cutting tool are positioned in the cutting groove cut by the cutting tool to continue the interrupted cutting action.

5. The numerical control device according to claim 1, wherein The movement instruction data calculated by the plurality of tool motion calculation units is data related to movement instructions for repeatedly performing the following motions: In which, the action is to cut simultaneously from different positions by multiple cutting tools including a first tool and a second tool different from the first tool among the multiple tools. If the second tool reaches the cutting groove cut by the first tool, the multiple cutting tools are retreated from the workpiece. While maintaining the relative front-to-back relationship between the multiple cutting tools, other tools among the multiple cutting tools different from the first tool are moved to the end position of the cutting groove cut by the first tool, and the cutting action is continued by the multiple cutting tools.

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