Machine tool control device

Abstract

Provided is a machine tool control device for controlling threading, the device being capable of automatically setting the threading amount for achieving threading as desired by an operator. A machine tool control device 1 is provided with: a machining condition acquisition unit 11 that acquires machining conditions for threading; a machining determination unit 12 that determines the type of machining from the machining conditions; a threading amount rule setting unit 13 that, on the basis of a determination result from the machining determination unit 12, determines setting rules, which is a method for setting the threading amount of threading; and a threading amount determination unit 20 that determines the threading amount for machining on the basis of the machining conditions and the setting rules.

Description

Machine tool control device

[0001] The present disclosure relates to a control device for a machine tool.

[0002] Conventionally, machine tools have performed swing machining, in which the tool and workpiece are swung relative to each other, to prevent chips that are continuously generated during machining from becoming entangled in the workpiece or cutting tool, which could result in machining defects or machine failure (see, for example, Patent Document 1).

[0003] In this type of swing machining, the tool path, which is the trajectory of the tool, is set to partially overlap the previous tool path, causing the tool to move away from the surface of the workpiece, creating a missed swing called an air cut, which shreds the chips.

[0004] Japanese Patent Application Laid-Open No. 2020-66169

[0005] In the case of orbital thread cutting, the operator often specifies the same depth of cut (position on the X axis) as in normal thread cutting without orbital motion. However, there are cases where this specified depth of cut is not suitable for actual orbital thread cutting.

[0006] For example, compared to threading without oscillation, swing threading requires more machining operations and therefore a longer cycle time due to the principle of swinging. Also, swing threading allows the cutting tool to cool down during air cutting, which could potentially shorten the cycle time by increasing the amount of cutting per operation, but this was not possible. Alternatively, in swing threading, in order to reduce the load on the cutting tool, it may be preferable to reduce the amount of cutting by reducing the depth of cut compared to normal threading without oscillation.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology in a control device of a machine tool that controls thread cutting, which automatically sets the cutting depth to achieve thread cutting according to the operator's requests.

[0008] The present disclosure relates to a control device for a machine tool that performs thread cutting on a workpiece using a cutting tool, the control device for a machine tool including: a machining condition acquisition unit that acquires machining conditions for the thread cutting; a machining judgment unit that determines the type of machining from the machining conditions; a cutting amount rule setting unit that determines a setting rule that is a method for setting the cutting amount for the thread cutting based on the judgment result of the machining judgment unit; and a cutting amount determination unit that determines the cutting amount during machining based on the machining conditions and the setting rule.

[0009] According to the present disclosure, it is possible to provide a technology in a control device of a machine tool that controls thread cutting, which automatically sets the cutting depth to achieve thread cutting according to the operator's request.

[0010] FIG. 1 is a functional block diagram of a control device for a machine tool according to a first embodiment of the present invention. FIG. 2 is a diagram showing an example of a machining program when oscillation machining is not performed in the first embodiment. FIG. 3 is a graph showing the positional relationship between a workpiece and a cutting tool when oscillation machining is not performed in the first embodiment. FIG. 4 is a diagram showing an example of a machining program when oscillation machining is performed in the first embodiment. FIG. 5 is a graph showing the positional relationship between a workpiece and a cutting tool when the cutting depth is changed by applying a first setting rule. FIG. 6 is a graph showing the positional relationship between a workpiece and a cutting tool during oscillation machining when the first setting rule is applied. FIG. 7 is a graph showing the positional relationship between a workpiece and a cutting tool during oscillation machining when the cutting depth is changed by applying a second setting rule. FIG. 8 is a graph showing the positional relationship between a workpiece and a cutting tool during oscillation machining when the second setting rule is applied. A flowchart showing an example of a threading command generation process by a control device for a machine tool. FIG. 9 is a graph showing the positional relationship between a workpiece and a cutting tool when the cutting depth is set by applying the setting rule of the second embodiment. A functional block diagram of a control device for a machine tool according to a third embodiment. A functional block diagram of a control device for a machine tool according to a fourth embodiment.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description of the second and subsequent embodiments, the same reference numerals will be used to designate components common to the first and second embodiments, and the description thereof will be omitted as appropriate.

[0012] First Embodiment FIG. 1 is a functional block diagram of a machine tool control device 1 according to a first embodiment of the present invention. The machine tool control device 1 shown in FIG. 1 is used to perform thread cutting using a cutting tool that oscillates radially relative to a workpiece. For convenience, FIG. 1 shows only a motor 3 that drives one feed axis. Furthermore, the cutting process according to this embodiment is not limited to a specific workpiece shape. That is, the present invention is applicable to cases where the workpiece has a tapered or arc-shaped portion on the cutting surface, requiring multiple feed axes (Z-axis and X-axis), and cases where the workpiece is cylindrical or columnar and only one specific feed axis (Z-axis) is sufficient.

[0013] The machine tool control device 1 of this embodiment is configured using a computer including memories such as ROM (read only memory) and RAM (random access memory), a CPU (control processing unit), and a communication control unit, all connected via a bus. The functions and operations of each functional unit, which will be described later, are achieved by cooperation between the CPU and memory installed in the computer and the control program stored in the memory. The machine tool control device 1 may also be configured with a CNC (computer numerical controller) or PLC (programmable logic controller), or may be connected to a higher-level computer that outputs machining conditions such as rotational speed in addition to the machining program.

[0014] As shown in FIG. 1, the machine tool control device 1 includes a machining condition acquisition unit 11, a machining judgment unit 12, a cutting amount rule setting unit 13, a cutting amount determination unit 20, a machining control unit 21, a memory unit 14, an input unit 15, and a display unit 16.

[0015] The machining condition acquisition unit 11 acquires machining conditions and swing conditions for swing machining of the workpiece. The machining conditions and swing conditions acquired by the machining condition acquisition unit 11 may be, for example, those stored in the storage unit 14, or may be those output from an external computer.

[0016] The machining conditions include information about the shape of the thread and cutting conditions for the workpiece. For example, information about the shape of the thread includes the thread lead (mm), thread diameter (mm), and thread angle (°). Cutting conditions for the workpiece include the spindle rotation speed S (1 / min), finishing allowance (mm), the number of finishing passes (times), and cutting position (mm). The cutting position is a reference position such as one end position (e.g., the lower end position) or the other end position (the upper end position) in the swing direction, and is not particularly limited to a specific position. Furthermore, the cutting position may be any information that can identify the cutting position, such as the cutting area. In this way, the cutting amount may be a length or an area, or may be information that identifies a position.

[0017] The oscillation conditions include information about the number of oscillations in the radial direction of the workpiece and information about the oscillation amplitude in the radial direction of the workpiece. Information about the number of oscillations in the radial direction of the workpiece includes an oscillation frequency magnification I (times), which indicates the oscillation frequency per rotation of the spindle. Information about the oscillation amplitude in the radial direction of the workpiece relative to the cutting tool and the workpiece includes an oscillation amplitude magnification K (times), which indicates the magnitude of the oscillation amplitude relative to the cutting depth in the radial direction of the workpiece during thread cutting.

[0018] The machining determination unit 12 determines the type of machining to be performed based on the machining conditions acquired by the machining condition acquisition unit 11. The machining determination unit 12 of the first embodiment determines whether the machining to be performed based on the machining conditions is thread cutting with oscillation or thread cutting without oscillation.

[0019] The cutting-in amount rule setting unit 13 sets setting rules for determining the cutting-in amount based on the determination result of the machining determination unit 12. The setting rules are set in advance so as to correspond to the type of machining determined by the machining determination unit 12. The setting rules may be stored in the storage unit 14 or may be output from an external computer.

[0020] In the setting rule of the first embodiment, the specified set cutting depth is not changed in the case of normal thread cutting without swinging, but is changed in the case of thread cutting with swinging. The setting rule will be described later.

[0021] The cutting depth determination unit 20 determines the cutting depth during actual machining based on the set cutting depth included in the machining conditions and the setting rules set in the cutting depth rule setting unit 13 .

[0022] The machining control unit 21 generates an operation command based on the cutting depth determined by the cutting depth determination unit 20, and performs operation control based on the operation command. The operation control drives the motor 3 and the like, moves the workpiece and the cutting tool, and performs thread cutting.

[0023] The storage unit 14 stores various information for controlling and machining the machine tool. In this embodiment, the storage unit 14 stores machining conditions and oscillation conditions. The machining conditions and oscillation conditions are, for example, those input by an operator into a machining program or those specified as machine tool parameters. The storage unit 14 may be configured to be located outside the control device 1 rather than inside it.

[0024] The input unit 15 inputs information related to processing in response to an operator's input operation on an input means (not shown), such as a keyboard or a touch panel. The information related to processing input by the input unit 15 is stored in the storage unit 14 or the like, or input to each unit of the control device 1.

[0025] The display unit 16 displays various information related to the machine tool, the control device 1, and machining. The display unit 16 is configured by, for example, a display.

[0026] The above has described the overall configuration of the control device 1. Next, a machining program that specifies thread cutting without swinging will be described.

[0027] 2 is a diagram showing an example of a machining program when oscillating machining is not performed in the first embodiment. The machining program shown in FIG. 2 is set by, for example, an operator.

[0028] "G76" in FIG. 2 is a command for one block in the machining program, and is a code that generates a movement block for multiple thread cutting operations. "Q" is a code that indicates the first cutting depth, "P" is a code that indicates the thread height, and "R" is a code that indicates the thread angle. "G76 X9.0 Z10.0 F2.0" and "Q10.0 R60.0" in the machining program are acquired as the thread cutting conditions (thread lead, thread angle, set cutting depth). In this example, the cutting depth X = 10.0 mm for the first thread cutting and the cutting depth X = 9.0 mm for the second thread cutting are acquired as the set cutting depths.

[0029] Figure 3 is a graph showing the positional relationship between the workpiece and the cutting tool T when no swing machining is performed in the first embodiment. When the machining program of Figure 2 is executed, the operation command shown in the graph of Figure 3 is generated. In this example, since the swing mode is not turned on, two thread cutting operations without swing are performed, one with a depth of cut X = 10.0 mm and the other with a depth of cut X = 9.0 mm (set depth of cut).

[0030] Next, a machining program specifying thread cutting with oscillation will be described. Fig. 4 is a diagram showing an example of a machining program for performing oscillation machining in the first embodiment. The machining program shown in Fig. 4 is set by, for example, an operator.

[0031] In addition to the description of the machining program in Figure 2, the machining program in Figure 4 has "G8.5 P3 I5.0 K2.0" added. "G8.5 P3" in the machining program indicates that the thread cutting oscillation mode is ON. Furthermore, "I5.0 K2.0" following "G8.5 P3" indicates oscillation conditions such as oscillation frequency and oscillation amplitude. In this example, the oscillation conditions are an oscillation frequency of 5.0 [Hz] and an oscillation amplitude of 2.0 [mm].

[0032] In the first embodiment, when the machining conditions indicate that oscillation is to be performed, as in the machining program shown in Fig. 4, a process is executed to newly set the cutting depth based on preset setting rules. The setting rules are set in advance in the control device 1 based on priorities. Below, a first setting rule and a second setting rule, which have different priorities, will be described.

[0033] The first setting rule will be described with reference to Figures 5 and 6. Figure 5 is a graph showing the positional relationship between the workpiece and the cutting tool T when the cutting depth is changed by applying the first setting rule. Figure 6 is a graph showing the positional relationship between the workpiece and the cutting tool T during swing machining when the first setting rule is applied.

[0034] The first setting rule prioritizes reducing the number of machining operations in order to shorten the cycle time, and specifies the depth of cut in the case of thread cutting with oscillation so that the number of operations is less than that of normal thread cutting.

[0035] In the example shown in FIG. 5, the set cutting position indicating that the thread position is 11.0 mm, the set cutting position is 10.0 mm, and the cutting position as the finishing position is 9.0 mm is acquired from the machining program.

[0036] Next, the cutting-in amount determination unit 20 acquires the number of cutting-in positions to be cancelled and the cancellation method from the setting rules set by the cutting-in amount rule setting unit 13. In this example, it is assumed that a rule for canceling even-numbered cutting increments has been set. The cutting-in amount determination unit 20 cancels even-numbered cutting increments counting from the thread position in accordance with the setting rules. In other words, when there is no oscillation, of the set cutting increments for thread cutting performed twice, the first cutting increment X = 10 mm is omitted. Then, as shown in FIG. 6, thread cutting with oscillation and thread cutting without oscillation are performed based only on the second cutting increment X = 9.0 mm.

[0037] The second setting rule will be described with reference to Figures 7 and 8. Figure 7 is a graph showing the positional relationship between the workpiece and the cutting tool T when the second setting rule is applied and the cutting depth is changed. Figure 8 is a graph showing the positional relationship between the workpiece and the cutting tool T during swing machining when the second setting rule is applied.

[0038] The second setting rule prioritizes reducing the load on the workpiece and cutting tool T per machining cycle, and in the case of thread cutting with oscillation, specifies the amount of cutting so that the number of executions is greater than for normal thread cutting.

[0039] In the example shown in FIG. 7, the set cutting position indicating that the thread position is 11.0 mm, the set cutting position is 10.0 mm, and the cutting position as the finishing position is 9.0 mm is also acquired from the machining program.

[0040] Next, the cutting-in amount determination unit 20 acquires the number of cutting-in positions to be added and the method for adding the cutting-in positions from the setting rules set by the cutting-in amount rule setting unit 13. In this example, the setting rules are for adding cutting positions to intermediate positions between the acquired cutting-in positions. A cutting-in amount of X=10.5 mm is added between the thread position 11.0 mm and the cutting-in amount X=10 mm, and a cutting-in amount of X=9.5 mm is added between the cutting-in amount X=10 mm and the cutting-in amount X=9.0 mm. That is, a total of four cutting-in amounts are specified: the first cutting-in amount X=10.5 mm, the second cutting-in amount X=10.0 mm, the third cutting-in amount X=9.5 mm, and the fourth cutting-in amount X=9.0 mm. In this way, when thread cutting is performed with oscillation, two additional cutting-in amounts are added to the set cutting-in amounts for thread cutting performed twice without oscillation. As shown in FIG. 8, thread cutting with and without swinging is performed for each of the depth of cut X=10.5 mm, the depth of cut X=10.0 mm, the depth of cut X=9.5 mm, and the depth of cut X=9.0 mm.

[0041] In the second setting rule, the depth of cut is added based on the position of the set depth of cut, but this method is not limited to this, and the depth of cut may be set according to a predetermined index. For example, the depth of cut may be changed to the position of the set depth of cut so that the maximum cutting amount at each depth of cut is constant. The depth of cut can be calculated from the maximum cutting amount using a known calculation method. In this example, thread cutting with and without oscillation is performed for the added first depth of cut X = 10.4 mm, second depth of cut X = 10.0 mm, third depth of cut X = 9.4 mm, and fourth depth of cut X = 9.0 mm, respectively.

[0042] Furthermore, the second setting rule may add an infeed position for each infeed amount according to a predetermined maximum cutting amount set for each infeed. In this example, a predetermined maximum cutting area is set in advance in the control device 1 instead of the predetermined infeed amount. The maximum cutting area here is the cutting area when the infeed position reaches its deepest position during oscillation. The setting rule calculates the predetermined infeed amount that results in the maximum cutting area using a known calculation method, and adds an infeed position between each infeed position.

[0043] Next, the flow of the thread cutting command generation process will be described with reference to Fig. 9. Fig. 9 is a flowchart showing an example of the thread cutting command generation process by the control device of the machine tool.

[0044] 9, when an operator issues an instruction to start machining, the machining condition acquisition unit 11 acquires threading conditions for performing threading (step S10). The threading conditions include, for example, the machining conditions including the cutting depth described above, and swing conditions. As described above, the threading conditions are acquired from the machining program stored in the storage unit 14, parameters set in the machine tool, and the like.

[0045] In the next step S10, the machining determination unit 12 determines whether or not the machining mode is a specific machining mode (thread cutting with swing) based on the machining conditions (step S11). In the first embodiment, the machining determination unit 12 advances the process to step S12 if the machining mode is thread cutting with swing (step S11; Yes), and advances the process to step S20 if the machining mode is thread cutting without swing (step S11; No).

[0046] First, a case where it is determined that the thread cutting process is to be performed with swing will be described. In step S12, the cutting-in amount rule setting unit 13 sets a setting rule based on the determination result of the process determination unit 12, and the cutting-in amount determination unit 20 newly specifies the cutting-in amount for the thread cutting process with swing based on the set cutting-in amount and the setting rule (see FIGS. 5 and 7).

[0047] After step S12, the machining control unit 21 generates a thread cutting command for swing machining based on the cutting depth determined by the cutting depth determination unit 20 (step S13), and swing thread cutting is performed (step S14).

[0048] Next, a case where it is determined that thread cutting is to be performed without swinging will be described. In step S20, the cutting-in amount rule setting unit 13 sets a setting rule based on the determination result of the machining determination unit 12, and the cutting-in amount determination unit 20 specifies the set cutting-in amount as the cutting-in amount for normal cutting without swinging.

[0049] Next, the machining control unit 21 generates a thread cutting command for normal machining to perform thread cutting without oscillation based on the cutting depth determined by the cutting depth determination unit 20 (step S21), and normal thread cutting without oscillation is performed (step S22).

[0050] According to the control device 1 of the first embodiment of the machine tool that performs thread cutting on a workpiece using the cutting tool T described above, the following effects are achieved.

[0051] The machine tool control device 1 according to this embodiment includes a machining condition acquisition unit 11 that acquires thread cutting conditions; a machining determination unit 12 that determines the type of machining based on the machining conditions; a cutting depth rule setting unit 13 that determines a setting rule for setting the depth of cut for the thread cutting based on the determination result of the machining determination unit 12; and a cutting depth determination unit 20 that determines the cutting depth during machining based on the machining conditions and the setting rule. This automatically sets the cutting depth reflecting the operator's priorities, allowing thread cutting to be performed appropriately for the actual situation. For example, if the cycle time needs to be shortened, the setting rule can be set to adjust the cutting depth to reduce the number of cuts, since the cutting heat of the cutting tool T can be cooled during air cutting (examples in FIGS. 5 and 6 ). Furthermore, if the load on the cutting tool T per cut is desired to be reduced, the setting rule can be set to adjust the cutting depth to increase the number of cuts, thereby reducing the cutting depth per cut (examples in FIGS. 7 and 8 ).

[0052] Furthermore, the machining determination unit 12 of this embodiment determines whether the machining is with or without swing cutting based on the machining conditions, and the cutting-in amount rule setting unit 13 determines the setting rule depending on whether swing cutting is performed or not. This makes it possible to determine swing cutting, which is greatly affected by the cycle time and the cutting tool T, and to perform thread cutting based on the cutting-in amount suitable for swing-type thread cutting.

[0053] Furthermore, the machining condition acquisition unit 11 of this embodiment acquires a preset set cutting depth, and the cutting depth determination unit 20 determines the cutting depth during machining based on the set cutting depth and the setting rules. As a result, even if the cutting depth is set in advance, it is automatically adjusted to reflect the operator's priorities, making it possible to easily achieve thread cutting with high productivity and safety.

[0054] Furthermore, in this embodiment, the cutting-in amount rule setting unit 13 sets a setting rule for adding a cutting position between multiple cutting-in positions acquired from the machining conditions by the machining condition acquisition unit 11 when it is determined that oscillation should be performed, and the cutting-in amount determination unit 20 sets a cutting amount according to the set cutting-in amount or the maximum cutting amount based on the setting rule so that the cutting-in interval or the maximum cutting amount in a cutting is constant. This automatically sets an operation command that prioritizes reducing the load on the workpiece and cutting tool T per machining cycle, making it possible to easily achieve machining that meets the operator's requirements.

[0055] Furthermore, the cutting-in amount rule setting unit 13 of this embodiment determines a setting rule for canceling at least one of the multiple cutting-in positions indicated by the set cutting-in amount. This automatically sets an operation command that prioritizes reducing the number of machining operations in order to shorten the cycle time, making it possible to easily achieve machining that meets the operator's requirements.

[0056] The machine tool control device 1 of the first embodiment has been described above, but it is not limited to the configuration of the above embodiment. For example, the setting rules are not limited to the contents described in the above embodiment, and the method for setting the cutting depth can be changed as appropriate depending on various conditions. Below, an embodiment different from the above embodiment will be described.

[0057] Second Embodiment Next, a control device 1 according to a second embodiment will be described. The basic configuration of the control device 1 according to the second embodiment is the same as the configuration shown in FIG.

[0058] In the second embodiment, the cutting depth per cut is set in advance not in the machining program but in the control device 1. For example, the cutting depth is stored in the storage unit 14 as a parameter set in the control device 1 of the machine tool. In this embodiment, the predetermined cutting depth is set to 0.7 mm.

[0059] The machining condition acquisition unit 11 acquires information indicating the cutting position from the machining conditions. For example, the machining condition acquisition unit 11 acquires a thread position of 11.0 mm and a finishing position (target position) of 9.0 mm as information indicating the cutting position.

[0060] In the second embodiment, too, when the machining conditions indicate that oscillation is to be performed, the control device 1 executes processing to newly set the cutting depth based on a preset setting rule.

[0061] The setting rules of the second embodiment will be described with reference to Fig. 10. Fig. 10 is a graph showing the positional relationship between the workpiece and the cutting tool T when the cutting depth is set by applying the setting rules of the second embodiment. The setting rules specify the cutting depth based on the thread position, which is the cutting depth position acquired from the machining conditions, the finishing position, and the predetermined cutting depth.

[0062] In the example of FIG. 10 , the depth of cut for the swing machining is specified by subtracting a predetermined depth of cut from the thread position of 11.0 mm to the finish position (target position) of 9.0 mm. In this example, 10.3 mm, calculated by subtracting the predetermined depth of cut of 0.7 from the thread position of 11.0 mm, is specified as the depth of cut for the first thread cutting. Next, 9.6 mm, calculated by subtracting the predetermined depth of cut of 0.7 from 10.3 mm, is specified as the depth of cut for the second thread cutting. Subtracting the predetermined depth of cut of 0.7 from 9.6 mm results in 8.9, which exceeds the finish position (target position) of 9.0 mm, so the finish position of 9.0 mm is specified as the depth of cut for the third thread cutting. Then, thread cutting with and without swing is performed for the specified depths of cut of 10.3 mm, 9.6 mm, and 9.0 mm.

[0063] In the second embodiment, the depth of cut is specified based on a predetermined depth of cut, but this is not limiting and the depth of cut may be determined according to a predetermined index. For example, the following method may be used. Instead of a predetermined depth of cut, a predetermined maximum cutting area is preset in the control device 1. The maximum cutting area here refers to the cutting area when the cutting position during oscillation reaches the deepest position. The setting rule calculates the predetermined depth of cut that results in the maximum cutting area using a known calculation method. The method for specifying the depth of cut for oscillation machining is the same as the process described above. In this example, thread cutting with oscillation and thread cutting without oscillation are performed for specified depths of cut of 10.3 mm, 9.6 mm, and 9.0 mm.

[0064] According to the control device 1 of the second embodiment of the machine tool that performs thread cutting on a workpiece using the cutting tool T described above, the following effects are achieved.

[0065] In this embodiment, for machining determined as specific machining by the machining determination unit 12, a setting rule for setting the cutting depth is determined for each cutting depth corresponding to a predetermined cutting depth or a predetermined maximum cutting area. As a result, even if a predetermined cutting depth or a predetermined maximum cutting area is set, an operation command corresponding to the operator's request is automatically set.

[0066] [Third Embodiment] Next, a control device 1a according to a third embodiment will be described with reference to Fig. 11. Fig. 11 is a functional block diagram of a control device 1a for a machine tool according to the third embodiment. The third embodiment differs from the above-described embodiments in that the control device 1a includes a sensor 30 that measures the temperatures of the threading cutting tool T, the drive motor, etc., but the other configurations are the same.

[0067] The control device 1a of the third embodiment is set with a setting rule similar to the first setting rule of the first embodiment. According to this setting rule, the current machining state (temperature) is detected by the sensor 30 when the cutting tool T is positioned at the start point. If the detection result of the sensor 30 indicates that there is room for improvement in the machining state, such as if the temperature is sufficiently low, the cutting amount determination unit 20a of the third embodiment performs processing to cancel cutting positions to be machined next and thereafter. For example, if the temperature is lower than a specified value, processing to cancel one cutting position is performed. In this way, a configuration may be adopted in which the setting rule is changed depending on the machining state.

[0068] [Fourth embodiment] Next, a control device 1b according to a fourth embodiment will be described with reference to Fig. 12. Fig. 12 is a functional block diagram of a control device 1b for a machine tool according to the fourth embodiment. The fourth embodiment differs from the above-described embodiments in that the control device 1b includes an upper limit value acquisition unit 31, but the other configurations are the same.

[0069] In the fourth embodiment, the upper limit value acquisition unit 31 acquires an upper limit value related to cutting. The upper limit value may be, for example, an upper limit value for the cutting depth, an upper limit value for the cutting amount, or an allowable load during cutting. The upper limit value is set taking into consideration the instantaneous maximum value when performing oscillation. The upper limit value is stored in the memory unit 14 as a machining program or a parameter of the control device 1 of the machine tool. The upper limit value may also be stored in an external storage device.

[0070] The cutting-in amount determination unit 20b of the fourth embodiment determines the actual cutting-in amount for thread cutting, reflecting the upper limit value acquired by the upper limit value acquisition unit 31. That is, if the result of following the setting rule exceeds the upper limit of any of the cutting-in amount, cutting amount, or allowable load during cutting, a process is executed to correct the cutting-in amount to the upper limit value or below the upper limit value. Alternatively, instead of providing a setting rule that sets the cutting-in amount according to a predetermined cutting-in amount or a predetermined maximum cutting area, a setting rule may be used that sets the cutting-in amount so that cutting is performed at the upper limit of any of the cutting-in amount, cutting amount, or allowable load during cutting for each cutting.

[0071] According to the control device 1b of the machine tool of the fourth embodiment, which performs thread cutting on a workpiece using the cutting tool T described above, the following effects are achieved.

[0072] The control device 1b of this embodiment further includes an upper limit value acquisition unit 31 that acquires an upper limit value related to cutting, and the cutting depth determination unit 20b determines the cutting depth by reflecting the upper limit value in addition to the machining conditions and setting rules. As a result, even when the cutting depth changes, such as in thread cutting with oscillation, the upper limit value is automatically reflected in the operation command, allowing for safe and reliable thread cutting without the operator having to specify it separately. Alternatively, thread cutting can be performed at the upper limit value for each cutting depth, allowing for highly efficient thread cutting.

[0073] In the above-described embodiment and modified examples, an example was introduced in which a machining program format uses code such as "G76" to generate multiple thread cutting movement blocks with a single command in the machining program. However, the present technology can also be applied to a case in which the operation shown in Figure 3 is programmed using code "G92" twice to generate one cycle of thread cutting (start point, X-axis positioning, thread cutting, return to start point), or a case in which a program is programmed to execute one cycle of thread cutting twice by combining code "G00" indicating positioning and code "G32" indicating thread cutting. In this case, the cutting depth during machining may be determined according to the set cutting depth obtained from the machining program, or the cutting depth during machining may be determined by obtaining the thread position or finishing position as in the second embodiment.

[0074] Furthermore, in the above embodiment and modified examples, the specific machining determined by the machining determination unit 12 is described as thread cutting with oscillation and thread cutting without oscillation, but this is not limited to this configuration. For example, a configuration may be adopted in which ultrasonic cutting is determined as a specific function. Also, a configuration may be adopted in which machining using a specific tool with excellent wear resistance is determined, and in that case, setting rules that take wear resistance into consideration are applied.

[0075] Furthermore, in the above embodiment, a command for alternately repeating thread cutting with and without swing motion is automatically generated, but this is not limited to this. For example, a configuration may be adopted in which thread cutting with swing motion is performed multiple times followed by thread cutting without swing motion at least once. In this case, in order to perform air cutting, it is preferable to perform machining control by adjusting the swing conditions so that the peaks and valleys of consecutive swing motion thread cuttings overlap. For example, the machining control unit 21 can overlap the peaks and valleys of consecutive swing motion thread cuttings by performing a process to shift the phase of the swing conditions by 180 degrees.

[0076] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0077] The following supplementary note is further disclosed regarding the above embodiment and modified examples: (Supplementary note 1) A control device (1, 1a, 1b) for a machine tool that performs thread cutting on a workpiece with a cutting tool (T), comprising: a machining condition acquisition unit (11) that acquires machining conditions for the thread cutting, a machining determination unit (12) that determines the type of machining from the machining conditions, a cutting-in amount rule setting unit (13) that determines a setting rule that is a method for setting the cutting-in amount for the thread cutting based on a determination result from the machining determination unit, and a cutting-in amount determination unit (20, 20a, 20b) that determines the cutting-in amount during machining based on the machining conditions and the setting rule.

[0078] (Supplementary Note 2) In the above-mentioned machine tool control device (1, 1a, 1b), the machining determination unit (12) determines whether the machining is to be performed with or without swing cutting based on the machining conditions, and the cutting depth rule setting unit (13) determines the setting rule depending on whether swing cutting is to be performed or not.

[0079] (Supplementary Note 3) In the above-mentioned machine tool control device (1, 1a, 1b), the machining condition acquisition unit (11) acquires a preset set cutting depth, and the cutting depth determination unit (20, 20a, 20b) determines the cutting depth during machining based on the set cutting depth and the setting rule.

[0080] (Note 4) In the above-mentioned machine tool control device (1, 1a, 1b), the cutting-in amount rule setting unit (13) sets a setting rule for adding a cutting-in position between a plurality of cutting-in positions acquired from the machining conditions by the machining condition acquisition unit (11) when it is determined that oscillation is to be performed, and the cutting-in amount determination unit (20, 20a, 20b) sets a cutting-in amount according to the predetermined index based on the setting rule so that the predetermined index becomes constant.

[0081] (Supplementary Note 5) In the above-described machine tool control device (1, 1a, 1b), the cutting-in amount rule setting unit (13) determines a setting rule for canceling at least one of the plurality of cutting-in positions indicated by the set cutting-in amount.

[0082] (Note 6) In the control device (1, 1a, 1b) of the above machine tool, for machining that the machining determination unit (12) determines as specific machining, a setting rule for setting the cutting depth is determined for each cutting depth according to a predetermined index.

[0083] (Supplementary Note 7) The control device (1b) for the machine tool further includes an upper limit value acquisition unit (31) that acquires an upper limit value related to cutting, and the cutting depth determination unit (20b) determines the cutting depth by reflecting the upper limit value in addition to the machining conditions and the setting rules.

[0084] REFERENCE SIGNS LIST 1, 1a, 1b Machine tool control device 11 Machining condition acquisition unit 12 Machining judgment unit 13 Cutting amount rule setting unit 20, 20a, 20b Cutting amount determination unit 31 Upper limit value acquisition unit T Cutting tool

Claims

1. A control device for a machine tool that performs thread cutting on a workpiece using a cutting tool, a machining condition acquisition unit that acquires machining conditions for thread cutting; a processing determination unit that determines a type of processing based on the processing conditions; a cutting depth rule setting unit that determines a setting rule, which is a method for setting the cutting depth of the thread cutting, based on the judgment result of the machining judgment unit; a cutting-in amount determination unit that determines a cutting-in amount during machining based on the machining conditions and the setting rules.

2. The machining determination unit determines whether the machining is to be performed with or without swing cutting based on the machining conditions, The control device for a machine tool according to claim 1 , wherein the cutting-in amount rule setting unit determines the setting rule depending on whether or not swinging is performed.

3. the machining condition acquisition unit acquires a preset set cutting depth, The control device for a machine tool according to claim 1 or 2, wherein the cutting-in amount determination unit determines the cutting-in amount during machining based on the set cutting-in amount and the setting rule.

4. the cutting-in amount rule setting unit sets a setting rule for adding a cutting position between the plurality of cutting-in positions acquired from the machining conditions by the machining condition acquisition unit when it is determined that oscillation is to be performed, The control device for a machine tool according to claim 3 , wherein the cutting-in amount determination unit sets the cutting-in amount according to the predetermined index based on the setting rule so that the predetermined index becomes constant.

5. The control device for a machine tool according to claim 3 , wherein the cutting-in amount rule setting unit determines a setting rule for canceling at least one of a plurality of cutting-in positions indicated by the set cutting-in amount.

6. 3. The control device for a machine tool according to claim 1, wherein for machining determined by the machining determination unit to be specific machining, a setting rule for setting the cutting-in amount is determined for each cutting-in amount corresponding to a predetermined index.

7. further comprising an upper limit value acquisition unit that acquires an upper limit value related to cutting; The control device for a machine tool according to claim 1 or 2, wherein the cutting-in amount determination unit determines the cutting-in amount by reflecting the upper limit value in addition to the machining conditions and the setting rules.