Control devices for machine tools

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

Technical Field

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

Background Art

[0002] Conventionally, in a machine tool, in order to avoid chips continuously generated during machining from getting entangled with the workpiece or cutting tool and causing machining defects or mechanical failures, etc., rocking machining is performed to relatively rock the tool and the workpiece (see, for example, Patent Document 1).

[0003] In this type of rocking machining, by setting a tool path, which is the locus of the tool, to partially overlap the previous tool path, an idle run called air cut is generated where the tool moves away from the surface of the workpiece to break the chips into small pieces.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in thread cutting rocking machining, the same cutting depth (position on the X - axis) as in normal thread cutting without rocking is often specified by the operator. However, there are cases where this specified cutting depth is not a value suitable for actual thread cutting rocking machining.

[0006] For example, compared to thread cutting without oscillation, oscillating thread cutting, due to its oscillation principle, increases the number of cuts and thus lengthens the cycle time. Also, in oscillating thread cutting, it was possible to cool the cutting tool's heat during air cutting, which offered the potential to shorten the cycle time by increasing the amount of material removed per cut, but this could not be utilized. Alternatively, in oscillating thread cutting, it may be preferable to reduce the depth of cut and thus the amount of material removed compared to conventional thread cutting without oscillation, in order to reduce the load on the cutting tool.

[0007] This disclosure has been made in view of the above-mentioned problems, and aims to provide a technology for a control device of a machine tool that controls thread cutting, in which the depth of cut is automatically set to achieve thread cutting according to the operator's request. [Means for solving the problem]

[0008] This disclosure relates to a control device for a machine tool that performs thread cutting on a workpiece using a cutting tool, comprising: a processing condition acquisition unit that acquires processing conditions for thread cutting; a processing determination unit that determines the type of processing from the processing conditions; a depth of cut rule setting unit that determines a setting rule which is a method for setting the depth of cut for thread cutting based on the determination result of the processing determination unit; and a depth of cut determination unit that determines the depth of cut during processing based on the processing conditions and the setting rule. [Effects of the Invention]

[0009] According to this disclosure, a control device for a machine tool that controls thread cutting can be provided, which automatically sets the depth of cut to achieve thread cutting according to the operator's request. [Brief explanation of the drawing]

[0010] [Figure 1] This is a functional block diagram of a control device for a machine tool according to the first embodiment of the present invention. [Figure 2]This figure shows an example of a machining program when oscillating machining is not performed in the first embodiment. [Figure 3] This graph shows the positional relationship between the workpiece and the cutting tool when oscillating machining is not performed in the first embodiment. [Figure 4] This figure shows an example of a machining program when performing oscillating machining in the first embodiment. [Figure 5] This graph shows the positional relationship between the workpiece and the cutting tool when the depth of cut is changed by applying the first setting rule. [Figure 6] This graph shows the positional relationship between the workpiece and the cutting tool during oscillating machining to which the first setting rule is applied. [Figure 7] This graph shows the positional relationship between the workpiece and the cutting tool when the depth of cut is changed by applying the second setting rule. [Figure 8] This graph shows the positional relationship between the workpiece and the cutting tool during oscillating machining when the second setting rule is applied. [Figure 9] This flowchart shows an example of the process by which a machine tool's control system generates thread cutting commands. [Figure 10] This graph shows the positional relationship between the workpiece and the cutting tool when the depth of cut is set according to the setting rules of the second embodiment. [Figure 11] This is a functional block diagram of the control device for a machine tool according to the third embodiment. [Figure 12] This is a functional block diagram of the control device for a machine tool according to the fourth embodiment. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the description of the second and subsequent embodiments, components common to the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0012] [First Embodiment] FIG. 1 is a functional block diagram of a control device 1 for a machine tool according to a first embodiment of the present invention. The control device 1 for the machine tool shown in FIG. 1 is for performing thread cutting with a cutting tool that swings in the radial direction with respect to a workpiece. In FIG. 1, for the sake of convenience, only a motor 3 that drives one feed axis is shown. Also, in the cutting process according to the present embodiment, the shape of the workpiece is not limited. That is, even when a plurality of feed axes (Z-axis and X-axis) are required because the workpiece has a tapered portion or an arc-shaped portion on the machining surface, or even when the workpiece is cylindrical or tubular and only a specific one axis (Z-axis) of the feed axis is sufficient, it is applicable.

[0013] The control device 1 for the machine tool of the present embodiment is configured using, for example, a computer including a memory such as a ROM (read only memory) and a RAM (random access memory), a CPU (control processing unit), and a communication control unit, which are connected to each other via a bus. The functions and operations of each functional unit described later are achieved by the cooperation of the CPU, memory, and control program stored in the memory mounted on the above computer. Also, the control device 1 for the machine tool may be composed of a CNC (Computer Numerical Controller), a PLC (Programmable Logic Controller), etc., or may be connected to a higher-level computer that outputs machining conditions such as machining programs and rotational speeds.

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

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

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

[0017] Also, the swinging conditions include information on the number of swings in the radial direction of the workpiece and information on the swing amplitude in the radial direction of the workpiece. Information on the number of swings in the radial direction of the workpiece includes the swing frequency magnification I (times) indicating the swing frequency per spindle rotation. Also, information on the swing amplitude in the relative radial direction of the cutting tool and the workpiece includes the swing amplitude magnification K (times) indicating the magnitude of the swing amplitude with respect to the cutting amount in the radial direction of the workpiece during screw 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 in the first embodiment determines whether the machining to be performed based on the machining conditions is screw cutting with swinging or screw cutting without swinging.

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

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

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

[0022] The machining control unit 21 generates an operation command based on the depth of cut determined by the depth of cut determination unit 20, and performs operation control based on the operation command. The operation control drives the motor 3 and other components, causing the workpiece and cutting tool to move and the thread cutting process to be performed.

[0023] The memory unit 14 stores various information for the control and machining of the machine tool. In this embodiment, the memory unit 14 stores machining conditions and oscillation conditions. Machining conditions and oscillation conditions are, for example, those entered into the machining program by the operator or specified as parameters of the machine tool. Note that the memory unit 14 may be located outside the control device 1 rather than inside it.

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

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

[0026] The overall configuration of control device 1 has been described above. Next, we will describe the machining program that specifies thread cutting without oscillation.

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

[0028] In Figure 2, "G76" is a single command in the machining program that generates multiple movement blocks for thread cutting. "Q" is a code indicating the depth of cut for the first cut, "P" is a code indicating the thread height, and "R" is a code indicating the thread angle. "G76 X9.0 Z10.0 F2.0" and "Q10.0 R60.0" in the machining program will be acquired as the thread cutting conditions (thread lead, thread angle, set depth of cut). In this example, the set depth of cut is acquired as X=10.0mm for the first thread cutting and X=9.0mm for the second thread cutting.

[0029] Figure 3 is a graph showing the positional relationship between the workpiece and the cutting tool T when oscillating machining is not performed in the first embodiment. When the machining program in Figure 2 is executed, the operation commands shown in the graph in Figure 3 will be generated. In this example, since the oscillating mode is not turned on, two thread cutting operations without oscillating will be performed with a depth of cut of X = 10.0 mm and a depth of cut of X = 9.0 mm (set depth of cut).

[0030] Next, we will describe a machining program that specifies thread cutting with oscillating motion. Figure 4 is a diagram showing an example of a machining program when performing oscillating motion machining in the first embodiment. The machining program shown in Figure 4 is set, for example, by an operator.

[0031] The machining program in Figure 4 includes the same information as the machining program in Figure 2, plus the addition of "G8.5 P3 I5.0 K2.0". "G8.5 P3" in the machining program indicates that the threading oscillation mode is ON. "I5.0 K2.0" following "G8.5 P3" indicates the oscillation conditions, such as the oscillation frequency and 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, as shown in the machining program in Figure 4, when the machining conditions indicate that oscillation will occur, a process is executed to newly set the depth of cut based on a pre-set setting rule. The setting rule is pre-set in the control device 1 based on priority. The first and second setting rules, which have different priorities, will be described below.

[0033] The first setting rule will be explained 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 depth of cut 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 oscillating machining when the first setting rule is applied.

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

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

[0036] Next, the depth of cut determination unit 20 obtains the number of cutting positions to cancel and the method of cancellation from the setting rules set by the depth of cut rule setting unit 13. In this example, it is assumed that a rule has been set to cancel even-numbered cutting positions. The depth of cut determination unit 20 cancels even-numbered cutting positions, counting from the thread position, according to the setting rules. That is, in the case of no oscillation, the first cutting amount X = 10 mm of the set depth of cut for the thread cutting process, which is performed twice, is omitted. Then, as shown in Figure 6, the thread cutting process with oscillation and the thread cutting process without oscillation will be performed based only on the second cutting amount X = 9.0 mm.

[0037] The second setting rule will be explained 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 depth of cut is changed by applying the second setting rule. Figure 8 is a graph showing the positional relationship between the workpiece and the cutting tool T during oscillating 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 pass, and specifies the depth of cut so that, in the case of thread cutting with oscillation, the number of passes is greater than in normal thread cutting.

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

[0040] Next, the depth of cut determination unit 20 obtains the number of additional cutting positions and the method for adding the cutting positions from the setting rules set by the depth of cut rule setting unit 13. In this example, the setting rule is to add a cutting position at an intermediate position between each of the obtained cutting positions. A cutting amount of X=10.5mm is added between the thread position 11.0mm and the cutting amount X=10mm, and a cutting amount of X=9.5mm is added between the cutting amount X=10mm and the cutting amount 9.0mm. That is, a total of four cutting amounts are specified: the first added cutting amount X=10.5mm, the second added cutting amount X=10.0mm, the third added cutting amount X=9.5mm, and the fourth added cutting amount X=9.0mm. In this way, the set cutting amount for thread cutting, which is performed twice when there is no oscillation, will have two more cutting amounts added when thread cutting with oscillation is performed. Then, as shown in Figure 8, for depths of cut X = 10.5 mm, X = 10.0 mm, X = 9.5 mm, and X = 9.0 mm, both oscillating and non-oscillating thread cutting operations are performed.

[0041] In the second setting rule, the depth of cut was added based on the position of the set depth of cut, but this method is not the only one that is allowed; the depth of cut can be set according to a predetermined indicator. For example, instead of the position of the set depth of cut, the cutting positions may be added so that the maximum cutting amount in each cut is constant. The depth of cut can be calculated from the maximum cutting amount using a known calculation method. In this example, for each of the added depths of cut X=10.4mm (1st cut), X=10.0mm (2nd cut), X=9.4mm (3rd cut), and X=9.0mm (4th cut), both oscillating and non-oscillating thread cutting operations will be performed.

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

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

[0044] As shown in Figure 9, when the operator gives an instruction to start machining, the machining condition acquisition unit 11 acquires the threading conditions for performing the threading (step S10). The threading conditions include, for example, machining conditions including the depth of cut and oscillation conditions as described above. The threading conditions are also acquired from the machining program stored in the memory unit 14 and parameters set in the machine tool, as described above.

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

[0046] First, let's explain the case where it is determined that the thread cutting process involves oscillation. In step S12, the depth of cut rule setting unit 13 sets a setting rule based on the determination result of the processing determination unit 12, and the depth of cut determination unit 20 newly specifies the depth of cut for thread cutting with oscillation based on the set depth of cut and the setting rule (see Figures 5 and 7).

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

[0048] Next, we will explain the case where it is determined that the thread cutting is performed without oscillation. In step S20, the depth of cut rule setting unit 13 sets the setting rule based on the determination result of the machining determination unit 12, and the depth of cut determination unit 20 specifies the set depth of cut as the depth of cut for normal machining without oscillation.

[0049] Next, the machining control unit 21 generates a threading command for normal machining to perform threading without oscillation based on the depth of cut determined by the depth of cut determination unit 20 (step S21), and normal threading 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 control device 1 of the machine tool according to this embodiment includes a machining condition acquisition unit 11 that acquires machining conditions for thread cutting, a machining determination unit 12 that determines the type of machining from the machining conditions, a depth of cut rule setting unit 13 that determines a setting rule, which is a method for setting the depth of cut for thread cutting, based on the determination result of the machining determination unit 12, and a depth of cut determination unit 20 that determines the depth of cut during machining based on the machining conditions and the setting rule. As a result, the depth of cut that reflects the operator's priorities is automatically set, and thread cutting suitable for the actual situation is performed. For example, if it is desired to shorten the cycle time, the setting rule can be set so that the depth of cut is adjusted to reduce the number of machining passes, as the machining heat of the cutting tool T can be cooled when air cut is performed, thereby shortening the cycle time (examples in Figures 5 and 6). Also, if it is desired to reduce the load on the cutting tool T in a single machining pass, the setting rule can be set so that the depth of cut is adjusted to increase the number of machining passes in order to reduce the depth of cut in a single pass, thereby reducing the load on the cutting tool T (examples in Figures 7 and 8).

[0052] Furthermore, the machining determination unit 12 in this embodiment determines from the machining conditions whether or not to perform oscillating cutting, and the depth of cut rule setting unit 13 determines the setting rule according to whether or not to perform oscillating. This makes it possible to identify oscillating cutting, which is greatly influenced by cycle time and cutting tool T, and to perform thread cutting based on a depth of cut suitable for thread cutting with oscillating.

[0053] Furthermore, the machining condition acquisition unit 11 of this embodiment acquires a preset depth of cut, and the depth of cut determination unit 20 determines the depth of cut during machining based on the preset depth of cut and the setting rules. As a result, even if the depth of cut is preset, it is automatically adjusted to reflect the operator's priorities, making it easy to achieve highly productive and safe thread cutting.

[0054] Furthermore, in this embodiment, the depth-of-cut rule setting unit 13 sets a setting rule to add a cutting position between a plurality of cutting positions acquired from the machining conditions by the machining condition acquisition unit 11 when it is determined that oscillation is to occur. The depth-of-cut determination unit 20 then sets the depth-of-cut amount according to the set depth-of-cut amount or the maximum cutting amount, based on the setting rule, so that the interval between cuts or the maximum cutting amount in each cut remains constant. As a result, an operation command that prioritizes reducing the load on the workpiece and cutting tool T per machining cycle is automatically set, making it easy to achieve machining that meets the operator's requirements.

[0055] Furthermore, the depth-of-cut rule setting unit 13 of this embodiment determines a setting rule that cancels at least one of the multiple cutting positions indicated by the set depth-of-cut. As a result, an operation command that prioritizes reducing the number of machining operations in order to shorten the cycle time is automatically set, making it easy to achieve machining that meets the operator's requirements.

[0056] The control device 1 for a machine tool according to the first embodiment has been described above, but the configuration is not limited to the above embodiment. For example, the setting rules are not limited to those described in the above embodiment, and the method for setting the depth of cut can be appropriately changed according to various conditions. The following describes embodiments that differ from the above embodiment.

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

[0058] In the second embodiment, the depth of cut per pass is pre-set in the control device 1, rather than in the machining program. For example, the depth of cut is stored in the storage unit 14 as a parameter set in the control device 1 of the machine tool. In this embodiment, a predetermined depth of cut 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 thread position of 11.0 mm and the finishing position (target position) of 9.0 mm are acquired by the machining condition acquisition unit 11 as information indicating the cutting position.

[0060] In the second embodiment as well, if the processing conditions indicate that oscillation will occur, the control device 1 executes a process to newly set the depth of cut based on a preset setting rule.

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

[0062] In the example in Figure 10, the depth of cut for oscillating machining is specified by subtracting a predetermined depth of cut from the thread position of 11.0 mm to the finished position (target position) of 9.0 mm. In this example, 10.3 mm, obtained 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, obtained 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 finished position (target position) of 9.0 mm, so the finished position of 9.0 mm is specified as the depth of cut for the third thread cutting. Then, oscillating and non-oscillating thread cutting are 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 was specified based on a predetermined depth of cut, but this method is not limited to this method; the depth of cut can be determined according to a predetermined index. For example, the following method may also be used: Instead of a predetermined depth of cut, a predetermined maximum cutting area is pre-set in the control device 1. The maximum cutting area here is the cutting area when the cutting position during oscillation reaches the deepest position. The setting rule is to calculate 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 oscillating machining is the same as the process described above. In this example as well, thread cutting with and without oscillation will be performed for the 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 operations that the machining determination unit 12 determines to be specific machining operations, setting rules are determined for setting the depth of cut according to a predetermined depth of cut or a predetermined maximum cutting area. As a result, even if a predetermined depth of cut or a predetermined maximum cutting area is set, an operation command corresponding to the operator's request will be automatically set.

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

[0067] The control device 1a of the third embodiment is configured with setting rules similar to the first setting rules of the first embodiment. In this setting rule, when the cutting tool T is positioned at the starting point, the current machining state (temperature) is detected by the sensor 30. If the detection result of the sensor 30 indicates that there is sufficient machining capacity, such as a sufficiently low temperature, the depth of cut determination unit 20a of the third embodiment cancels the cutting positions to be machined in subsequent steps. For example, if the temperature is lower than a specified value, a process to cancel one cutting position is executed. Thus, the setting rules may be changed according to the machining state.

[0068] [Fourth Embodiment] Next, the control device 1b of the fourth embodiment will be described with reference to Figure 12. Figure 12 is a functional block diagram of the control device 1b of the machine tool according to the fourth embodiment. The fourth embodiment differs from the above embodiment 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 acquisition unit 31 acquires upper limits related to cutting. The upper limit may be, for example, an upper limit for the depth of cut, an upper limit for the amount of material removed, or an allowable load during cutting. The upper limit is set considering the instantaneous maximum value when oscillating is performed. The upper limit is stored in the storage unit 14 as a parameter of the machining program or the control device 1 of the machine tool. The upper limit may also be stored in an external storage device.

[0070] In the fourth embodiment, the depth of cut determination unit 20b determines the actual depth of cut for thread cutting by reflecting the upper limit value acquired by the upper limit value acquisition unit 31. That is, if, as a result of following the setting rules, any of the upper limits of the depth of cut, the amount of material removed, or the allowable load during cutting are exceeded, the unit performs a process to correct the depth of cut to the upper limit or below the upper limit. Alternatively, instead of setting rules to set a predetermined depth of cut or a depth of cut corresponding to a predetermined maximum cutting area, the setting rules may be set to set the depth of cut so that each cut is machined at any of the upper limits of the depth of cut, the amount of material removed, or the allowable load during 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 acquisition unit 31 that acquires an upper limit value related to cutting, and the depth of cut determination unit 20b determines the depth of cut by reflecting the upper limit value in addition to the processing conditions and setting rules. As a result, even when the depth of cut changes, such as in thread cutting with oscillation, the upper limit value is automatically reflected in the operation command, so that thread cutting can be achieved with high safety and reliability without the operator having to specify it separately. Alternatively, since processing can be done at the upper limit value for each cut, thread cutting can be achieved with high efficiency.

[0073] In the embodiments and modifications described above, examples were shown using code that generates multiple thread cutting movement blocks with a single command block in the machining program, such as "G76," as the format of the machining program. However, this technology is also applicable when, for example, the operation in Figure 3 is programmed using the code "G92," which generates one cycle of thread cutting (start point, X-axis positioning, thread cutting, return to the start point), twice, or when a program is created that executes one cycle of thread cutting twice by combining the code "G00" indicating positioning and the code "G32" indicating thread cutting. In this case, the amount of cutting during machining may be determined according to the set cutting amount obtained from the machining program, or the amount of cutting during machining may be determined by obtaining the thread position or the finishing position, as in the second embodiment.

[0074] Furthermore, while the above embodiments and modifications describe examples of thread cutting with oscillation and thread cutting without oscillation as specific processes determined by the processing determination unit 12, the configuration is not limited to these examples. For example, the system may be configured to identify ultrasonic cutting as a specific function. Alternatively, the system may be configured to identify processes using specific tools with excellent wear resistance, and in such cases, setting rules that take wear resistance into consideration may be applied.

[0075] Furthermore, in the above embodiment, commands are automatically generated to alternately repeat thread cutting with oscillation and thread cutting without oscillation, but the system is not limited to this. For example, the system may be configured to perform thread cutting without oscillation at least once after multiple cycles of thread cutting with oscillation. In this case, it is preferable to adjust the oscillation conditions so that the peaks and valleys of the continuous thread cutting with oscillation overlap in order to perform air cut-off processing. For example, the machining control unit 21 can overlap the peaks and valleys in the continuous thread cutting with oscillation by shifting the phase of the oscillation conditions by 180 degrees.

[0076] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. Furthermore, these embodiments can be implemented in combination. For example, the order of operations and processes in the embodiments described above are shown as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0077] The following additional information is disclosed regarding the above embodiments and modifications. (Note 1) A control device (1,1a,1b) for a machine tool that performs thread cutting on a workpiece using a cutting tool (T), A machining condition acquisition unit (11) acquires the machining conditions for thread cutting, A processing determination unit (12) that determines the type of processing from the processing conditions, Based on the determination result of the processing determination unit, a cutting depth rule setting unit (13) determines a setting rule which is a method for setting the cutting depth for thread cutting, A cutting depth determination unit (20, 20a, 20b) that determines the cutting depth during machining based on the machining conditions and the setting rules, It is equipped with.

[0078] (Note 2) In the control devices (1,1a,1b) of the above-mentioned machine tools, The machining determination unit (12) determines from the machining conditions whether or not to perform oscillating cutting, The cutting depth rule setting unit (13) determines the setting rule depending on whether or not oscillation is performed.

[0079] (Note 3) In the control devices (1,1a,1b) of the above-mentioned machine tools, The processing condition acquisition unit (11) acquires a preset depth of cut, The depth of cut determination unit (20, 20a, 20b) determines the depth of cut during machining based on the set depth of cut and the setting rule.

[0080] (Note 4) In the control devices (1,1a,1b) of the above-mentioned machine tools, When the cutting depth rule setting unit (13) determines that oscillation is to occur, it sets a setting rule to add a cutting position between the multiple cutting positions obtained from the machining conditions by the machining condition acquisition unit (11). The cutting depth determination unit (20, 20a, 20b) sets the cutting depth according to the predetermined index so that the predetermined index remains constant, based on the setting rule.

[0081] (Note 5) In the control devices (1,1a,1b) of the above-mentioned machine tools, The aforementioned cutting depth rule setting unit (13) A setting rule is determined to cancel at least one of the multiple cut positions indicated by the aforementioned set cut amount.

[0082] (Note 6) In the control devices (1,1a,1b) of the above-mentioned machine tools, For any machining that the machining determination unit (12) determines to be a specific machining operation, a setting rule is determined for setting the depth of cut according to a predetermined index.

[0083] (Note 7) In the control device (1b) of the above-mentioned machine tool, The system further includes an upper limit acquisition unit (31) for acquiring an upper limit related to cutting, The depth of cut determination unit (20b) determines the depth of cut by taking into account the processing conditions and setting rules, as well as the upper limit. [Explanation of symbols]

[0084] 1, 1a, 1b Control devices for machine tools 11 Machining condition acquisition section 12 Processing judgment section 13 Cutting depth rule setting unit 20, 20a, 20b Cutting depth determination section 31 Upper limit 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 the machining conditions for thread cutting, A processing determination unit that determines the type of processing from the processing conditions, Based on the determination result of the processing determination unit, a cutting depth rule setting unit determines a setting rule which is a method for setting the cutting depth for thread cutting, A control device for a machine tool, comprising: a depth of cut determination unit that determines the amount of cut during machining based on the machining conditions and the setting rules.

2. The machining determination unit determines from the machining conditions whether or not to perform oscillating cutting, The control device for a machine tool according to claim 1, wherein the cutting depth rule setting unit determines the setting rule depending on whether or not to perform oscillation.

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

4. When the cutting depth rule setting unit determines that oscillation is to occur, it sets a setting rule to add a cutting position between the multiple cutting positions obtained from the processing conditions by the processing condition acquisition unit. The control device for a machine tool according to claim 3, wherein the depth of cut determination unit sets the depth of cut according to the predetermined index so that the predetermined index remains constant, based on the setting rules.

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

6. The control device for a machine tool according to claim 1 or 2, wherein for any machining determined by the machining determination unit to be a specific machining operation, a setting rule is determined to set the depth of cut for each depth of cut corresponding to a predetermined indicator.

7. It further includes an upper limit acquisition unit that acquires an upper limit for cutting, The control device for a machine tool according to claim 1 or 2, wherein the depth of cut determination unit determines the depth of cut by reflecting the upper limit in addition to the processing conditions and the setting rules.

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