Control device for machine tool

Abstract

The present invention provides a technique that, in a control device for a machine tool for thread cutting machining that controls both swing and non-swing, enables a machining program to be easily set and enables gas cutting to be reliably performed. A control device (1) for a machine tool is provided with: a cut-in position acquisition unit (11) that acquires a cut-in position for thread cutting; a margin acquisition unit (12) that acquires a margin set so that the cutting tool swings beyond the cut-in position during swinging thread cutting; a swing amplitude information acquisition unit (13) that acquires swing amplitude information indicating the swing amplitude of the swing thread cutting; and a threading command generation unit (20) that generates, on the basis of the cut-in position, the allowance, and the oscillation amplitude information, a threading command that oscillates such that at least one end position in the oscillation direction crosses the cut-in position.

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 prevent chips continuously generated during machining from winding around a workpiece or a cutting tool and causing machining defects or mechanical failures, etc., oscillatory machining in which a tool is relatively oscillated with respect to a workpiece is performed (for example, refer to Patent Document 1 and Patent Document 2).

[0003] In such oscillatory machining, the tool path, that is, the tool trajectory, is set to partially overlap the previous tool path. As a result, an idle swing called air-cut in which the tool moves away from the workpiece surface is generated to break the chips.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-124793

[0007] Patent Document 2: International Publication No. 2016 / 067372 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, in thread cutting, oscillatory machining and non-oscillatory machining are carried out in combination. In the case of performing both oscillatory machining and non-oscillatory machining, from the viewpoint of simplifying the machining program, the cutting-in position (for example, the position on the X-axis) is mostly specified as the same position.

[0010] However, in the case of performing oscillatory thread cutting with the cutting-in position specified by an operator being one end position of the oscillation (for example, the lower end position), although programming can be easily performed, since one end position of the oscillation is specified, a margin for air-cut cannot be obtained. In actual machining, the oscillation amplitude often decays with respect to the oscillation command. Therefore, if a margin considering the decay cannot be ensured, air-cut may not be properly performed.

[0011] The present disclosure has been made in view of the above problems, and an object thereof is to provide a technique that can easily set a machining program and can reliably perform air-cut in a control device for a machine tool that controls both oscillatory and non-oscillatory thread cutting.

[0012] Means for Solving the Problems

[0013] The present disclosure relates to a control device for a machine tool that performs thread cutting on a workpiece using a cutting tool. Among them, the control device has: an approach position acquisition unit that acquires the approach position of the thread cutting; a margin acquisition unit that acquires a margin, which is set such that in oscillatory thread cutting, the cutting tool swings beyond the approach position; an oscillation amplitude information acquisition unit that acquires oscillation amplitude information indicating the oscillation amplitude of the oscillatory thread cutting; and a thread cutting command generation unit that generates a thread cutting command for swinging in a manner that at least one end position in the swing direction exceeds the approach position based on the approach position, the margin, and the oscillation amplitude information.

[0014] Advantages of the Invention

[0015] According to the present disclosure, a technique can be provided in which in a control device for a machine tool that controls both oscillatory and non-oscillatory thread cutting, a machining program can be easily set, and gas cutting can be reliably performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a functional block diagram of a control device for a machine tool according to a first embodiment of the present invention.

[0017] Figure 2 is a diagram showing an example of a machining program according to the first embodiment.

[0018] Figure 3 is a graph showing the positional relationship between the workpiece and the cutting tool in the first embodiment.

[0019] Figure 4 is a graph showing the upper end position and the lower end position of the swing in the first embodiment Figure 3 magnified view of the graph.

[0020] Figure 5 is a graph showing the positional relationship between the workpiece and the cutting tool for multiple cycles in the first embodiment.

[0021] Figure 6 is a graph showing the paths of the cutting tool in oscillatory thread cutting and non-oscillatory thread cutting of the prior art.

[0022] Figure 7 is a graph showing the paths of the cutting tool in oscillatory thread cutting and non-oscillatory thread cutting of the present embodiment.

[0023] Figure 8 is a graph showing the positional relationship between the workpiece and the cutting tool in the second embodiment.

[0024] Figure 9It is an enlarged view of a diagram showing the upper and lower end positions of the swing in the second embodiment. Figure 8 of the diagram.

[0025] Figure 10 It is a diagram showing the positional relationship between the workpiece and the cutting tool in multiple cycles in the second embodiment.

[0026] Figure 11 It is a functional block diagram showing the structure of the thread cutting command generation unit in the third embodiment.

[0027] Figure 12 It is a diagram showing the positional relationship between the workpiece and the cutting tool in the method for generating a thread cutting command in the third embodiment.

[0028] Figure 13 It is a diagram showing the positional relationship between the workpiece and the cutting tool in the method for generating a thread cutting command in the fourth embodiment.

[0029] Figure 14 It is a diagram showing the positional relationship between the workpiece and the cutting tool in the method for generating a thread cutting command in the fifth embodiment.

[0030] Figure 15 It is a functional block diagram showing the structure of the thread cutting command generation unit in the sixth embodiment.

[0031] Figure 16 It is a diagram showing the positional relationship between the workpiece and the cutting tool in the method for generating a thread cutting command in the sixth embodiment.

[0032] Figure 17 It is a functional block diagram showing the structure of the thread cutting command generation unit in the seventh embodiment.

[0033] Figure 18 It is a diagram showing the positional relationship between the workpiece and the cutting tool in the method for generating a thread cutting command in the seventh embodiment.

[0034] Figure 19 It is a functional block diagram of the control device of the machine tool in the eighth embodiment. Detailed Embodiments

[0035] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, in the descriptions after the second embodiment, the same reference numerals are given to the structures common to the first embodiment, and the description thereof is appropriately omitted.

[0036] [First Embodiment]

[0037] Figure 1 It is a functional block diagram of the control device 1 of the machine tool according to the first embodiment of the present invention. Figure 1The control device 1 of the machine tool shown performs thread cutting by a cutting tool that swings radially with respect to the workpiece. In addition, in Figure 1 , for convenience, only the motor 3 that drives one feed axis is shown. In addition, in the cutting process of this embodiment, the shape of the workpiece is not limited. That is, even when the workpiece has a taper or an arc-shaped portion on the machining surface and multiple feed axes (Z-axis and X-axis) are required, or even when the workpiece is cylindrical or tubular and only a specific one axis (Z-axis) of the feed axis is sufficient, it can be applied.

[0038] The control device 1 of the machine tool in this embodiment is constituted by, for example, a computer having the following parts: memories such as a ROM (read only memory) and a RAM (random access memory) interconnected via a bus, a CPU (control processing unit), and a communication control unit. The functions and operations of each functional unit described later are achieved through the cooperation of the CPU, the memories, and the control programs stored in the memories mounted on the above computer. In addition, the control device 1 of the machine tool can be constituted by a CNC (Computer Numerical Controller), a PLC (Programmable Logic Controller), etc., and can be connected to an upper computer that outputs machining conditions such as rotational speed in addition to the machining program.

[0039] As Figure 1 shown, the control device 1 of the machine tool has: an approach position acquisition unit 11, a margin acquisition unit 12, a swing amplitude information acquisition unit 13, a thread cutting instruction generation unit 20, a machining control unit 21, a storage unit 14, an input unit 15, and a display unit 16.

[0040] The approach position acquisition unit 11 acquires the approach position of the cutting tool with respect to the workpiece during thread cutting. The approach position can be stored in the storage unit 14, for example, or can be output from an external computer.

[0041] The margin acquisition unit 12 acquires a margin as information for setting a swing waveform to swing beyond the approach position acquired by the approach position acquisition unit 11. The margin is information that determines the amplitude of the swing beyond the approach position, for example. The margin can be stored in the storage unit 14, for example, or can be output from an external computer.

[0042] The swing amplitude information acquisition unit 13 acquires swing amplitude information indicating the swing amplitude from machining conditions and the like described later. The swing amplitude can be stored in the storage unit 14, for example, or can be output from an external computer.

[0043] The thread cutting instruction generation unit 20 generates a thread cutting instruction for performing thread cutting machining. The thread cutting instruction generation unit 20 generates a thread cutting instruction based on the cutting-in position obtained by the cutting-in position acquisition unit 11, the allowance obtained by the allowance acquisition unit 12, and the swing amplitude obtained by the swing amplitude information acquisition unit 13. In addition, the details of the generation process of the thread cutting instruction will be described later.

[0044] The machining control unit 21 performs motion control according to the thread cutting instruction generated by the thread cutting instruction generation unit 20. Through the motion control, the motor 3 etc. are driven, the workpiece and the cutting tool move, and the thread cutting machining is executed.

[0045] The storage unit 14 stores various information for the control or machining of the machine tool. In the present embodiment, the storage unit 14 stores machining conditions and swing conditions. The machining conditions and swing conditions are, for example, conditions input by the operator into the machining program or conditions specified as machine tool parameters. In addition, the storage unit 14 may not be configured inside the control device 1, but may be configured externally.

[0046] The swing conditions stored in the storage unit 14 include: information related to the number of swings in the radial direction of the workpiece, and information related to the swing amplitude in the radial direction of the workpiece. As the information related to the number of swings in the radial direction of the workpiece, the swing frequency magnification I (times) can be cited, which represents the swing frequency per revolution of the main shaft. In addition, as the information related to the swing amplitude in the radial direction of the workpiece relative to the cutting tool and the workpiece, the swing amplitude magnification K (times) can be cited, which represents the magnitude of the swing amplitude relative to the cutting-in amount in the radial direction of the workpiece for the thread cutting machining.

[0047] The machining conditions stored in the storage unit 14 include: information related to the screw shape, cutting conditions for the workpiece, etc. For example, as the information related to the screw shape, the lead (mm) of the screw, the diameter (mm) of the screw, the angle (°) of the thread tooth, etc. can be cited. As the cutting conditions for the workpiece, the rotational speed S (1 / min) of the main shaft, the finishing amount (mm), the number of finishing machining times (times), the cutting-in position (mm), etc. can be cited. The cutting-in position is a reference position such as one end position (for example, the lower end position) or the other end position (the upper end position) in the swing direction, and the position is not particularly limited. And as long as the information such as the cutting area can determine the cutting-in position, the cutting-in position is sufficient. In this way, the cutting-in amount can be a length, an area, or information for determining a position.

[0048] The input unit 15 inputs information related to machining according to the input operation of the operator on an input unit (not shown) such as a keyboard or a touch panel. The information related to machining input through the input unit 15 is stored in the storage unit 14 etc., or input into each part of the control device 1.

[0049] The display unit 16 displays various information related to the machine tool, the control device 1, and the machining. The display unit 16 is constituted by a display, for example.

[0050] As described above, the overall structure of the control device 1 has been described. Next, the flow of the generation process of the swing command of the control device 1 of the present embodiment will be described.

[0051] Figure 2 It is a diagram showing an example of a machining program of the first embodiment. In the machining program, “I5.0 K1.2” of the code “G8.5” represents swing conditions such as a swing frequency or a swing amplitude. “G92” is a code that generates one cycle of the thread cutting process by a single block command. Next, “X10.00 Z10.00 F2.0” following “G92” represents the machining conditions of the thread cutting showing the position or the feed rate.

[0052] The generation process of the swing command will be described. In the generation process of the swing command, first, the swing amplitude information acquisition unit 13 acquires swing amplitude information indicating an amplitude of 1.2 [mm] from “K1.2” in the machining program.

[0053] Next, the cutting-in position acquisition unit 11 acquires the machining conditions (pitch, lead, etc.) of the tapping from “G92 X10.00 Z10.00 F2.0” in the machining program. Then, the cutting-in position acquisition unit 11 analyzes from the description of “X10.00” that the cutting-in position in the thread cutting process is X = 10.0 [mm].

[0054] Then, the margin acquisition unit 12 acquires the margin from “G8.5 P3 I5.0 K1.2 L0.1” in the machining program. In addition, although it is acquired from the machining program in this example, it is not limited thereto. For example, the margin can also be acquired from the parameters set for the machine tool. And the margin may not be directly specified. Information indicating a magnification factor relative to the cutting-in amount per thread cutting can be acquired as the information representing the margin.

[0055] Next, with reference to Figure 3 and Figure 4 the thread cutting command generation unit 20 will be described. Figure 3 It is a diagram showing the positional relationship between the workpiece and the cutting tool T in the first embodiment. Figure 4 It is a Figure 3 magnified view of the diagram showing the upper end position and the lower end position of the swing in the first embodiment.

[0056] The thread cutting command generation unit 20 determines one end position, i.e., the upper end position, of the swing operation and the other end position, i.e., the lower end position, of the swing operation.

[0057] The thread cutting command generation unit 20 first sets the lower end position of the swinging motion according to the cutting-in position obtained by the cutting-in position acquisition unit 11 and the allowance obtained by the allowance acquisition unit 12. As Figure 3 and Figure 4 shown, in this example, 9.9 obtained by subtracting the allowance of 0.1 [mm] from the cutting-in position X = 10.0 [mm] is determined as the lower end position.

[0058] The thread cutting command generation unit 20 determines the upper end position according to the swing amplitude obtained by the swing amplitude information acquisition unit 13. In this example, 11.2 [mm] obtained by adding the swing amplitude of 1.2 [mm] to the cutting-in position of 10.0 [mm] is determined as the upper end position.

[0059] The thread cutting command generation unit 20 generates a swing command according to the swing condition obtained from the machining program and the upper end position and the lower end position of the generated swing. For example, it can swing in a sine wave, and as long as it is a periodic signal, it can also be a triangular wave or the like.

[0060] Next, with reference to Figure 5 an example of generating swing commands for multiple cycles will be described. Figure 5 is a diagram showing the positional relationship between the workpiece and the cutting tool T for multiple cycles in the first embodiment. One cycle is, for example, a series of actions from the start point of the cutting tool T shown in Figure 5 until it contacts the workpiece and is machined and then returns to the start point again. As Figure 5 shown, the thread cutting command generation unit 20 generates a thread cutting command for performing thread cutting machining for multiple cycles.

[0061] In Figure 5 the example, the cutting process is divided into a step of forming a cut-in by swinging in the X-axis direction and a step of forming a non-swing cut-in after the cut-in. Swing thread cutting machining is performed in the first, third, fifth, and seventh cycles. As it enters the first, third, fifth, and seventh cycles, the cutting depth becomes deeper. The swing conditions such as the amplitude are set so that the cutting trajectory of each cut-in with swing is located at a position radially outside the workpiece surface. Then, non-swing thread cutting machining is performed in the second, fourth, sixth, and eighth cycles.

[0062] The path of the swing thread cutting machining and the path of the non-swing thread cutting machining cross each other, thereby realizing the gas cutting of the cut chips. For example, the swing command is generated so that the depth on the lower end side of the first swing thread cutting machining crosses the depth of the second thread cutting machining. Thus, in each cut-in accompanied by swing, the cut chips can also be shredded. Even in the final thread groove cutting machining that does not include swing, the cut chips can be shredded, and a highly accurate machining surface can be realized.

[0063] Here, the prior art will be described with reference to Figure 6 the following. Figure 6 FIG. is a diagram showing the paths of the cutting tool T in oscillatory thread cutting and non-oscillatory thread cutting of the prior art. As Figure 6 shown, in the oscillatory thread cutting of the prior art, the amplitude of the waveform representing the actual path of the cutting tool T decays, and the amplitude of the waveform representing the path of the cutting tool T in the command becomes smaller. In the Figure 6 example of, the path of the sixth non-oscillatory thread cutting intersects the path of the seventh oscillatory thread cutting to become a state where gas cutting is possible. However, the path of the seventh oscillatory thread cutting and the path of the eighth non-oscillatory thread cutting intersect in the command due to amplitude decay, but do not actually intersect, resulting in a state where gas cutting cannot be performed.

[0064] In order to reliably perform gas cutting, it is considered to generate a command with a larger swing amplitude to ensure the gas cutting margin. However, on the lower swing side, its position is directly specified in the program, so the gas cutting margin on the lower swing side cannot be obtained.

[0065] Figure 7 FIG. is a diagram showing the paths of the cutting tool T in oscillatory thread cutting and non-oscillatory thread cutting of the present embodiment. Regarding this point, as Figure 7 shown, according to the structure of the present embodiment, even when the actual swing amplitude decays compared to the swing amplitude in the command, a swing command is generated in advance considering the decay, so the paths of the oscillatory thread cutting and the non-oscillatory thread cutting intersect. In this example, the path of the seventh oscillatory thread cutting, which did not intersect in the prior art, intersects the path of the eighth non-oscillatory thread cutting, and gas cutting is performed.

[0066] According to the control device 1 of the machine tool of the first embodiment for thread cutting the workpiece by the cutting tool T described above, the following effects are achieved.

[0067] The control device 1 of the machine tool according to this embodiment has: a cutting-in position acquisition unit 11 that acquires the cutting-in position of thread cutting; a remaining amount acquisition unit 12 that acquires the remaining amount, which is set such that in oscillatory thread cutting, the cutting tool T swings beyond the cutting-in position; an oscillation amplitude information acquisition unit 13 that acquires oscillation amplitude information indicating the oscillation amplitude of oscillatory thread cutting; and a thread cutting command generation unit 20 that generates a thread cutting command for swinging in such a manner that at least one end position in the swinging direction crosses the cutting-in position based on the cutting-in position, the remaining amount, and the oscillation amplitude information. Thus, the ease of programming of the machining program can be maintained, and the oscillation waveform can be set to a waveform considering the remaining amount. Therefore, the control device 1 of the machine tool that can reliably perform gas cutting can be realized.

[0068] The thread cutting command generation unit 20 determines one end position (lower end position) in the swinging direction based on the cutting-in position and the remaining amount, and determines the other end position (upper end position) in the swinging direction based on the oscillation amplitude information, and generates a thread cutting command based on the one end position and the other end position. Thus, the one end position and the other end position of the amplitude swing can be calculated and determined without performing complex processing. Therefore, the arithmetic cost for setting the oscillation waveform at a position where reliable gas cutting can be performed can be effectively reduced.

[0069] The control device 1 of the machine tool according to the first embodiment has been described above, but is not limited to the structure of the above embodiment. Hereinafter, an embodiment different from the above embodiment will be described.

[0070] [Second Embodiment]

[0071] Next, the control device 1 according to the second embodiment will be described. The generation process of the swing command performed by the thread cutting command generation unit 20 in the control device 1 according to the second embodiment is different, and the structure other than this is the same as that of the first embodiment. In the first embodiment, the lower end position is determined first, and the upper end position is determined based on the lower end position and the oscillation amplitude, but in the second embodiment, the upper end position is determined first.

[0072] Refer to Figure 8 and Figure 9 , and the generation process of the swing command performed by the thread cutting command generation unit 20 according to the second embodiment will be described. Figure 8 is a diagram showing the positional relationship between the workpiece and the cutting tool T in the second embodiment. Figure 9 is a diagram showing the upper end position and the lower end position of the swing in the second embodiment Figure 8 magnified view of the diagram.

[0073] The thread cutting instruction generation unit 20 first sets the upper end position of the swinging motion based on the cutting-in position obtained by the cutting-in position acquisition unit 11 and the allowance obtained by the allowance acquisition unit 12. As Figure 8 and Figure 9 shown, in this example, 10.1 obtained by adding the allowance of 0.1 [mm] to the cutting-in position X = 10.0 [mm] is determined as the upper end position.

[0074] The thread cutting instruction generation unit 20 determines the lower end position based on the swing amplitude obtained by the swing amplitude information acquisition unit 13. In this example, 8.8 [mm] obtained by subtracting the swing amplitude of 1.2 [mm] from the cutting-in position of 10.0 [mm] is determined as the lower end position.

[0075] In this way, the thread cutting instruction generation unit 20 generates an instruction for performing oscillatory thread cutting machining in such a manner that the upper end position is X = 10.1 [mm] and the lower end position is X = 8.8 [mm].

[0076] Next, with reference to Figure 10 an example of generating swing instructions for multiple cycles will be described. Figure 10 is a diagram showing the positional relationship between the workpiece and the cutting tool T for multiple cycles in the first embodiment. The thread cutting instruction generation unit 20 generates swing instructions for performing cutting machining by dividing it into a step of forming a cutting-in by swinging in the X-axis direction and a step of forming a non-swing cutting-in after the cutting-in. In Figure 10 the example of, non-swing thread cutting machining is performed in the first, third, fifth, and seventh cycles. Then, oscillatory thread cutting machining is performed in the second, fourth, and sixth cycles. The path of the oscillatory thread cutting machining intersects with the path of the non-swing thread cutting machining, thereby achieving the gas cutting of the cut chips.

[0077] [Third Embodiment]

[0078] Next, a method for generating thread cutting instructions different from the first embodiment will be described. Figure 11 is a functional block diagram showing the structure of the thread cutting instruction generation unit 20a of the third embodiment. Figure 12 is a diagram showing the positional relationship between the workpiece and the cutting tool T in the method for generating thread cutting instructions of the third embodiment. In addition, in the third embodiment, the structure other than the thread cutting instruction generation unit 20a is the same as that of the above embodiment.

[0079] As Figure 11 shown, the thread cutting instruction generation unit 20a includes: a movement instruction generation unit 25 that generates movement instructions, and a swing instruction generation unit 26 that generates swing instructions.

[0080] The movement instruction generation unit 25 generates a movement instruction for controlling the position of the cutting tool T. The movement instruction is generated in such a way that the cutting tool T moves to the cutting-in position in thread cutting. The swing instruction generation unit 26 generates a swing instruction for swinging the cutting tool T relative to the workpiece. The swing instruction is generated taking into account the allowance.

[0081] In Figure 12 the example, the movement instruction generation unit 25 generates a movement instruction F1 based on the cutting-in position of 10 mm. The swing instruction generation unit 26 calculates the swing instruction F2 by the formula of Mathematical Formula 1 shown below. In the formula of Mathematical Formula 1, A represents the amplitude [mm], L represents the allowance [mm], and θ represents the swing phase [deg]. In Figure 12 the example, the swing amplitude A is set to 1.0 mm and the allowance L is set to 0.1 mm.

[0082] [Mathematical Formula 1]

[0083] F2 = (A + L) × (1 - cosθ) - L

[0084] The thread cutting instruction generation unit 20a generates a thread cutting instruction for performing thread cutting with swing by superimposing the swing instruction F2 and the movement instruction F1, where the swing instruction F2 is calculated by the formula of Mathematical Formula 1 by the swing instruction generation unit 26, and the movement instruction F1 is generated by the movement instruction generation unit 25. As shown in the formula of Mathematical Formula 1 and Figure 12 shown, "A + L" becomes the swing amplitude represented by the swing instruction, and "L" becomes the compensation amount (offset). In this way, the machining operation is performed according to the thread cutting instruction in which the movement instruction and the swing instruction are superimposed.

[0085] [Fourth Embodiment]

[0086] The fourth embodiment is described, in which the movement instruction and the swing instruction are increased by a method different from that of the third embodiment to generate a thread cutting instruction. Figure 13 is a diagram showing the positional relationship between the workpiece and the cutting tool T in the method for generating a thread cutting instruction according to the fourth embodiment.

[0087] In Figure 13 the example shown, F2 can be expressed by the formula of Mathematical Formula 2 below. In the formula of Mathematical Formula 2, A represents the amplitude [mm], L represents the allowance [mm], and θ represents the swing phase [deg]. In Figure 13 the example, the swing amplitude A is also set to 1.1 mm and the allowance L is set to 0.1 mm.

[0088] [Mathematical Formula 2]

[0089] F2 = (A) × (1 - cosθ) - L

[0090] The thread cutting instruction generation unit 20a generates a thread cutting instruction for performing oscillatory thread cutting by superimposing the oscillation instruction F2 and the movement instruction F1. Here, the oscillation instruction F2 is calculated by the oscillation instruction generation unit 26 according to the formula of the above mathematical formula 2, and the movement instruction F1 is generated by the movement instruction generation unit 25. As shown in the formula of the mathematical formula 2 and Figure 13 shown, "A" directly becomes the oscillation amplitude. In this way, the machining operation is performed according to the thread cutting instruction in which the movement instruction and the oscillation instruction are superimposed.

[0091] The control device 1 of the machine tool according to the third and fourth embodiments of the thread cutting of the workpiece by the cutting tool T described above has the following effects.

[0092] In the third and fourth embodiments, the thread cutting instruction generation unit 20a includes: a movement instruction generation unit 25 that generates a movement instruction for moving the cutting tool T in thread cutting; an oscillation instruction generation unit 26 that generates an oscillation instruction according to oscillation amplitude information, and the oscillation instruction determines the oscillation amplitude action in thread cutting. The thread cutting instruction generation unit 20a superimposes the oscillation instruction compensated according to the margin L and the movement instruction to generate a thread cutting instruction. Thus, at a position where oxy-fuel cutting can be reliably performed by using the superimposed processing of the movement instruction and the oscillation instruction, the oscillation waveform can be easily set.

[0093] [Fifth Embodiment]

[0094] Furthermore, a fifth embodiment in which a thread cutting instruction is directly generated without superimposing a movement instruction and an oscillation instruction will be described. Figure 14 is a diagram showing the positional relationship between the workpiece and the cutting tool T in the method for generating the thread cutting instruction of the fifth embodiment. As Figure 14 shown, the thread cutting machining instruction is directly generated without superimposing a movement instruction and an oscillation instruction. In this example, the oscillation amplitude A is set to 1.0 mm, the margin L is set to 0.1 mm, and "A + L" is the oscillation amplitude.

[0095] [Sixth Embodiment]

[0096] Next, a sixth embodiment in which a thread cutting instruction is generated by a method different from the above-described embodiments will be described. In the sixth embodiment, the thread cutting instruction generation unit 20b generates a thread cutting instruction in such a manner that the cutting start position of the oscillatory thread cutting is different from the cutting start position of the non-oscillatory thread cutting.

[0097] Figure 15 is a functional block diagram showing the structure of the thread cutting instruction generation unit 20b of the sixth embodiment. Figure 16It is a diagram showing the positional relationship between the workpiece and the cutting tool T in the method for generating a thread cutting command according to the sixth embodiment.

[0098] As Figure 15 shown, the thread cutting command generation unit 20b has a non-sway cutting-in position determination unit 30. The non-sway cutting-in position determination unit 30 determines the non-sway cutting-in position based on the cutting-in position acquired by the cutting-in position acquisition unit 11 and the allowance acquired by the allowance acquisition unit 12.

[0099] In the present embodiment, the allowance acquisition unit 12 functions as a displacement amount acquisition unit that acquires the displacement amount for changing the cutting-in position as the allowance for changing the sway waveform position. In Figure 16 the example shown, the allowance of 0.1 [mm] is added to the cutting-in position X = 10.00 [mm], and 10.10 [mm] is determined as the cutting-in position for non-sway thread cutting.

[0100] According to the control device 1 of the machine tool according to the sixth embodiment for thread cutting the workpiece with the cutting tool T described above, the following effects are achieved.

[0101] The thread cutting command generation unit 20b of the sixth embodiment has: a non-sway cutting-in position determination unit 30 that sets the non-sway cutting-in position for non-sway thread cutting based on the cutting-in position and the allowance, and the thread cutting command generation unit 20b generates the following thread cutting command: in the sway thread cutting, thread cutting is performed according to the cutting-in position acquired by the cutting-in position acquisition unit 11, and in the non-sway thread cutting, thread cutting is performed according to the non-sway cutting-in position set by the non-sway cutting-in position determination unit 30. Thus, by a simple process of adjusting the cutting-in position in non-sway thread cutting, a structure capable of ensuring the allowance for gas cutting can be realized.

[0102] [Seventh Embodiment]

[0103] Next, a seventh embodiment for generating a thread cutting command by a method different from the above-described embodiments will be described. Figure 17 It is a functional block diagram showing the structure of the thread cutting command generation unit 20c according to the seventh embodiment. Figure 18 It is a diagram showing the positional relationship between the workpiece and the cutting tool T in the method for generating a thread cutting command according to the seventh embodiment.

[0104] As Figure 17 shown, the thread cutting command generation unit 20c has a pre-processing cutting-in position determination unit 31. The pre-processing cutting-in position determination unit 31 determines the non-sway cutting-in position based on the cutting-in position acquired by the cutting-in position acquisition unit 11 and the allowance acquired by the allowance acquisition unit 12.

[0105] In the present embodiment, the margin acquisition unit 12 also functions as a displacement amount acquisition unit that acquires the displacement amount for changing the plunge position as the margin for changing the position of the swing waveform. In Figure 18 the example shown, 9.9 [mm] obtained by subtracting the margin of 0.1 [mm] from X = 10.00 [mm] is determined as the plunge position before machining.

[0106] The pre-machining plunge position determination unit 31 determines the above-mentioned plunge position at a timing before performing the swing thread cutting machining. The thread cutting command generation unit 20 generates a thread cutting command based on the plunge position and outputs it to the machining control unit 21. The machining control unit 21 performs a positioning process based on the plunge position determined by the pre-machining plunge position determination unit 31, and then performs the swing cutting machining.

[0107] According to the control device 1 of the machine tool according to the seventh embodiment for thread cutting machining of a workpiece by the cutting tool T described above, the following effects are achieved.

[0108] The thread cutting command generation unit 20c of the seventh embodiment includes: a pre-machining plunge position determination unit 31 that sets a plunge position for swing during swing thread cutting machining according to the plunge position and the margin, and the thread cutting command generation unit 20c generates the following thread cutting command: After positioning at the plunge position determined by the pre-machining plunge position determination unit 31 before machining starts, perform swing thread cutting machining.

[0109] [Eighth Embodiment]

[0110] Next, refer to Figure 19 the control device 1a of the eighth embodiment will be described. Figure 19 is a functional block diagram of the control device of the machine tool according to the eighth embodiment. The difference in the structure of the control device 1a of the eighth embodiment from that of the control device 1 of the above embodiment is that it further has a machining accuracy determination unit 35 and the processing of the thread cutting command generation unit 20d.

[0111] The machining accuracy determination unit 35 determines the degree of machining accuracy according to the description in the machining program. The degree of machining accuracy determined by the machining accuracy determination unit 35 is determined, for example, according to the code type recorded in the machining program or the dedicated determination code attached near the code.

[0112] In the determination of the machining accuracy level, the case of determination based on the code type is described. For example, the "G76" code is a code that generates a movement block for multiple thread cutting processes through the instruction of a single block in the machining program. When the "G76" code is recorded in the machining program, it can be configured to determine the importance of the machining accuracy of each cycle of thread cutting based on the target value recorded in the block following "G76". For example, the final finishing process can be set as the process with the highest importance, and in multiple cycles, the importance of the machining accuracy is set to increase as it approaches the final finishing process.

[0113] In the determination of the machining accuracy level, the case of determination through a dedicated determination code is described. For example, when dedicated discrimination codes (such as characters like "L0") are added to the blocks of "G32" and "G92" in the machining program, the machining accuracy level is determined based on this discrimination code. In this case, the discrimination code itself contains information indicating the importance of the machining accuracy.

[0114] The thread cutting instruction generation unit 20d performs the following processing: processing to correct the allowance according to the level of machining accuracy determined by the machining accuracy determination unit 35. For example, in the case of the final finishing process, the importance of the machining accuracy is the highest. Therefore, the thread cutting instruction generation unit 20d sets the allowance to 0 and reduces the allowance in the stage near the final finishing process. The reduction amount of the allowance can decrease as it approaches the stage near the final finishing process. In this case, the closer it is to the stage near the final finishing process, the relatively larger the allowance is.

[0115] According to the control device 1a of the machine tool of the eighth embodiment that performs thread cutting on the workpiece with the cutting tool T as described above, the following effects are achieved.

[0116] The control device 1a of the machine tool of the present embodiment further has: a machining accuracy determination unit 35 that determines the machining accuracy level, and the thread cutting instruction generation unit 20d sets: the value of the allowance corresponding to the machining accuracy level determined by the machining accuracy determination unit 35. Thus, the machining accuracy is reflected in the allowance, and it is possible to achieve a high level of balance between high machining accuracy and reliable oxy-fuel cutting.

[0117] In addition, in the above embodiment, instructions for alternately repeating oscillatory thread cutting and non-oscillatory thread cutting are automatically generated, but it is not limited to this.

[0118] For example, it can also be configured to perform at least one non-oscillating thread cutting operation after performing multiple oscillating thread cutting operations. In this case, for gas cutting processing, it is preferable to adjust the oscillation conditions in such a way that the peaks and valleys of consecutive oscillating thread cutting operations overlap to perform processing control. For example, the thread cutting instruction generation units 20, 20a to 20d can overlap the peaks and valleys in consecutive oscillating thread cutting operations by performing a process of shifting the phase of the oscillation conditions by 180 degrees.

[0119] The present disclosure has been described in detail, but the present disclosure is not limited to the above-described respective embodiments. These embodiments can be subjected to various additions, replacements, changes, partial deletions, etc. within the scope of not departing from the spirit of the present disclosure, or within the scope of not departing from the spirit of the present disclosure derived from the content recited in the claims and its equivalents. In addition, these embodiments can also be implemented in combination. For example, in the above embodiments, the order of each operation and the order of each process are shown as an example and are not limited thereto. In addition, the same applies to the cases where numerical values or mathematical formulas are used in the description of the above embodiments.

[0120] Regarding the above embodiments and modification examples, the following remarks are also disclosed.

[0121] (Remark 1)

[0122] A control device (1, 1a) for a machine tool, which performs thread cutting on a workpiece by a cutting tool (T), wherein,

[0123] The control device (1, 1a) has:

[0124] An approach position acquisition unit (11) that acquires the approach position of the thread cutting operation;

[0125] A remaining amount acquisition unit (12) that acquires a remaining amount, which is set such that the cutting tool (T) swings beyond the approach position in the oscillating thread cutting operation;

[0126] An oscillation amplitude information acquisition unit (13) that acquires oscillation amplitude information indicating the oscillation amplitude of the oscillating thread cutting operation; and

[0127] A thread cutting instruction generation unit (20, 20a to 20d) that generates a thread cutting instruction that swings in such a way that at least one end position in the swing direction goes beyond the approach position based on the approach position, the remaining amount, and the oscillation amplitude information.

[0128] (Remark 2)

[0129] In the control device (1) of the machine tool,

[0130] The thread cutting instruction generation unit (20) determines one end position in the swinging direction based on the cutting-in position and the allowance, and determines the other end position in the swinging direction based on the swinging amplitude information, and generates a thread cutting instruction based on the one end position and the other end position.

[0131] (Supplementary Note 3)

[0132] In the control device (1) of the machine tool,

[0133] The thread cutting instruction generation unit (20a) includes:

[0134] A movement instruction generation unit (25) that generates a movement instruction for moving the cutting tool (T) during thread cutting; and

[0135] A swing instruction generation unit (26) that generates a swing instruction according to the swing amplitude information, and this swing instruction determines the action of the swing amplitude during thread cutting.

[0136] The thread cutting instruction generation unit (20a) superimposes the swing instruction compensated according to the allowance on the movement instruction to generate a thread cutting instruction.

[0137] (Supplementary Note 4)

[0138] In the control device (1) of the machine tool,

[0139] The thread cutting instruction generation unit (20c) includes: a cutting-in position determination unit before machining (31) that sets a cutting-in position for swinging during swing thread cutting according to the cutting-in position and the allowance.

[0140] The thread cutting instruction generation unit (20c) generates the following thread cutting instruction: After positioning at the cutting-in position determined by the cutting-in position determination unit before machining (31) before machining starts, swing thread cutting is performed.

[0141] (Supplementary Note 5)

[0142] A control device (1, 1a) of a machine tool, which performs thread cutting on a workpiece by a cutting tool (T), wherein

[0143] The control device (1, 1a) includes:

[0144] A cutting-in position acquisition unit (11) that acquires the cutting-in position of thread cutting;

[0145] An allowance acquisition unit (12) that acquires an allowance, and this allowance is set such that the cutting tool (T) crosses the cutting-in position during non-swing thread cutting;

[0146] A swing amplitude information acquisition unit (13) that acquires swing amplitude information indicating the swing amplitude of swing thread cutting; and

[0147] A thread cutting command generation unit (20, 20a to 20d) that generates a thread cutting command based on the cutting position, the allowance, and the swing amplitude information,

[0148] The thread cutting command generation unit (20b) includes: a non-swing cutting position determination unit (30) that sets a non-swing cutting position for non-swing thread cutting based on the cutting position and the allowance,

[0149] The thread cutting command generation unit (20b) generates the following thread cutting command: In swing thread cutting, thread cutting is performed based on the cutting position acquired by the cutting position acquisition unit (11), and in non-swing thread cutting, thread cutting is performed based on the non-swing cutting position set by the non-swing cutting position determination unit (30).

[0150] (Supplementary Note 6)

[0151] In the control device (1, 1a) of the machine tool,

[0152] The control device (1, 1a) further includes: a machining accuracy determination unit (35) that determines the degree of machining accuracy,

[0153] The thread cutting command generation unit (20d) sets: the value of the allowance corresponding to the degree of machining accuracy determined by the machining accuracy determination unit (35).

[0154] Symbol Explanation

[0155] 1, 1a Control device of the machine tool

[0156] 11 Cutting position acquisition unit

[0157] 12 Allowance acquisition unit

[0158] 13 Vibration amplitude information acquisition unit

[0159] 20, 20a to 20d Thread cutting command generation unit

[0160] 25 Movement command generation unit

[0161] 26 Swing command generation unit

[0162] 30 Non-swing cutting position determination unit

[0163] 31 Pre-machining cutting position determination unit

[0164] 35 Machining accuracy determination unit

[0165] T cutting tool.

Claims

1. A control device for a machine tool, the machine tool performing thread cutting on a workpiece with a cutting tool, characterized in that, the control device has: a cutting-in position acquisition unit that acquires the cutting-in position of the thread cutting; a margin acquisition unit that acquires a margin, the margin being set such that in oscillatory thread cutting, the cutting tool swings beyond the cutting-in position; an oscillation amplitude information acquisition unit that acquires oscillation amplitude information, the oscillation amplitude information indicating the oscillation amplitude of the oscillatory thread cutting; and a thread cutting command generation unit that generates a thread cutting command for swinging in a manner that at least one end position in the swing direction goes beyond the cutting-in position, based on the cutting-in position, the margin, and the oscillation amplitude information.

2. The control device for a machine tool according to claim 1, characterized in that, the thread cutting command generation unit determines one end position in the swing direction based on the cutting-in position and the margin, and determines the other end position in the swing direction based on the oscillation amplitude information, and generates a thread cutting command based on the one end position and the other end position.

3. The control device for a machine tool according to claim 1, characterized in that, the thread cutting command generation unit has: a movement command generation unit that generates a movement command for moving the cutting tool during thread cutting; and an oscillation command generation unit that generates an oscillation command according to the oscillation amplitude information, the oscillation command determining the oscillation amplitude action during thread cutting, the thread cutting command generation unit superimposes the oscillation command compensated according to the margin on the movement command to generate a thread cutting command.

4. The control device for a machine tool according to claim 1, characterized in that, the thread cutting command generation unit has: a pre-processing cutting-in position determination unit that sets a cutting-in position for oscillation during oscillatory thread cutting according to the cutting-in position and the margin, the thread cutting command generation unit generates the following thread cutting command: after positioning at the cutting-in position determined by the pre-processing cutting-in position determination unit before the start of processing, perform oscillatory thread cutting.

5. A control device for a machine tool, the machine tool performing thread cutting on a workpiece with a cutting tool, characterized in that, the control device has: a cutting-in position acquisition unit that acquires the cutting-in position of the thread cutting; a margin acquisition unit that acquires a margin, the margin being set such that in non-oscillatory thread cutting, the cutting tool goes beyond the cutting-in position; an oscillation amplitude information acquisition unit that acquires oscillation amplitude information, the oscillation amplitude information indicating the oscillation amplitude of the oscillatory thread cutting; and a thread cutting command generation unit that generates a thread cutting command based on the cutting-in position, the margin, and the oscillation amplitude information, the thread cutting command generation unit has: a non-oscillation cutting-in position determination unit that sets a non-oscillation cutting-in position during non-oscillatory thread cutting according to the cutting-in position and the margin. The thread cutting instruction generation unit generates the following thread cutting instructions: in the case of oscillatory thread cutting machining, thread cutting machining is performed according to the cutting position obtained by the cutting position acquisition unit, and in the case of non-oscillatory thread cutting machining, thread cutting machining is performed according to the non-oscillatory cutting position set by the non-oscillatory cutting position determination unit.

6. The control device for a machine tool according to any one of claims 1 to 5, characterized in that the control device further includes: a machining accuracy determination unit that determines the degree of machining accuracy, the thread cutting instruction generation unit sets: the value of the allowance corresponding to the degree of machining accuracy determined by the machining accuracy determination unit.

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