Machine tool

Abstract

To provide a machine tool capable of performing a novel vibration work which is not disclosed hitherto.SOLUTION: A control part of a machine tool causes a work holding part and a tool holding part to perform a feed operation which causes a work holding part and a tool holding part to relatively move along an axial direction and, at the same time, causes the work holding part and the tool holding part to perform a vibration operation which relatively vibrates in a radial direction. The control part performs vibration turning cycle which performs turning operation accompanying vibration operation after performing cutting-in operation a plurality of times, makes the phase of the vibration operation with respect to a rotation phase of the work-piece the reverse phase between vibration turning cycles before and after the operations, and a moving locus of a tool in the turning operation is operated so as to be partially crossed between vibration turning cycles before and after the operations. The control part performs finishing turning operations as the turning operations which do not accompany vibration operation a plurality of times after the plural times of the vibration turning cycles.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This invention relates to a machine tool for turning a workpiece.

Background Art

[0002] Hitherto, as a machine tool for turning a workpiece, there has been known a machine tool including a tool holding part for holding a tool, a workpiece holding part for holding a workpiece, a rotational drive part for rotating the workpiece holding part about the axis center of the workpiece, a feed mechanism part for relatively moving the workpiece holding part and the tool holding part in a direction along the axis, and a control part for controlling the movement of the feed mechanism part based on an NC program. Such machine tools include NC lathes and multi-tasking machines.

[0003] Among the chips generated in such turning, there may be long chips that curl around the tool. When such chips are generated, there is a risk of scratching the machined surface of the workpiece or applying a high load to the tool, causing damage to the tool. In particular, in the case of thread cutting, the feed rate of the tool in the Z-axis direction (axis) depends on the thread pitch to be machined, and since this speed is faster than that in general turning, the influence received from the chips is large. Therefore, a new machining method such as that in Patent Document 1 has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the field of turning, various machining modes are required according to the machining performance of the machine tool, the shape and material of the tool, the shape and material of the workpiece, etc., and machining corresponding thereto is required.

Means for Solving the Problem

[0006] Therefore, it provides a machine tool, an information processing apparatus, a method, a program, etc. that can perform new processing.

Effect of the Invention

[0007] According to the present invention, new processing can be performed.

Brief Explanation of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0009] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing the main configuration of the motion mechanism system of the machine tool according to this embodiment, and FIG. 2 is a block diagram showing the main configuration of the control system.

[0010] As shown in FIGS. 1 and 2, the machine tool 1 in this example is a so-called NC lathe that turns a workpiece W with a tool 8. Such an NC lathe is generally capable of performing operations such as outer diameter machining, inner diameter machining, end face machining, drilling, grooving, and threading on the workpiece W. In this example, in particular, it is devised so that threading can be preferably performed.

[0011] As shown in FIG. 1, the machine tool 1 includes a main shaft 3 with a chuck 5 attached to its tip, a headstock 2 that rotatably holds the main shaft 3 about its axis, a main shaft motor 4 that rotates the main shaft 3, a tool post 6 as a tool holding part that holds the tool 8, a feed mechanism part 7 that moves the tool post 6, and a control device 10 as a control part that controls the operations of the main shaft motor 4 and the feed mechanism part 7.

[0012] The chuck 5 includes a plurality (generally three) of gripping jaws 5a provided to approach and separate from each other, and the workpiece W is gripped (held) by the gripping jaws 5a. The chuck 5 functions as a workpiece holding part that holds the workpiece W, and the main shaft motor 4 functions as a rotational drive part that rotates the chuck 5 together with the main shaft 3.

[0013] The feed mechanism part 7 includes a Z-axis feed mechanism (not shown) that moves the tool post 6 in the Z-axis direction, which is the direction along the axis of the main shaft 3, and an X-axis feed mechanism (not shown) that moves the tool post 6 in the X-axis direction, which is perpendicular to the Z-axis. Under the control of the control device 10, the tool post 6 is moved in the X-axis direction and the Z-axis direction.

[0014] As shown in Fig. 2, the control device 10 mainly includes a program storage unit 11, a program analysis unit 12, a spindle control unit 13, a feed control unit 14, and a parameter storage unit 15. The control device 10 is composed of a computer including a CPU, a RAM, a ROM, etc. The functions of the program analysis unit 12, the spindle control unit 13, and the feed control unit 14 are realized by a computer program, and the processes described later are executed. Also, the program storage unit 11 and the parameter storage unit 15 are composed of an appropriate storage medium such as a RAM.

[0015] The program storage unit 11 is a functional unit that stores an NC program for machining the workpiece W. An NC program is appropriately input from the outside in advance and stored in the program storage unit 11. Generally, an NC program has a configuration in which NC codes are sequentially described in block units. And each block includes, for example, NC codes related to the rotation of the spindle 3, the movement of the cutting edge (turning action part) of the tool 8, the ON and OFF of the coolant, etc. Taking an example, "M03" is an NC code (M code) that defines the forward rotation of the spindle 3, "M04" is an NC code (M code) that defines the reverse rotation of the spindle 3, and "S****" is an NC code (S code) that defines the rotation speed of the spindle 3.

[0016] Also, "G00" is an NC code (G code) that moves the tool 8 at a rapid feed speed, "G01" is an NC code (G code) that moves the tool 8 at a set cutting feed speed, "F****" is an NC code (F code) that defines the feed speed of the tool 8, and "X****" and "Z****" are NC codes that define the movement positions of the cutting edge of the tool 8 in the workpiece coordinate system (X-Z coordinate system). Also, in this example, in particular, "G985" is used as a G code that defines thread cutting with vibration (vibratory thread cutting). And by these NC codes, the operations of the spindle 3 and the tool 8 are set (defined) and created as one NC program.

[0017] The program analysis unit 12 is a functional unit that reads and executes the NC program stored in the program storage unit 11. While sequentially reading the NC program, it recognizes (analyzes) the described NC code, and according to the recognized NC code, when the NC code is related to the rotation control of the main shaft 3, it transmits a corresponding control signal to the main shaft control unit 13. When the NC code is related to the feed control of the feed mechanism unit 7, it transmits a corresponding control signal to the feed control unit 14.

[0018] The main shaft control unit 13 controls the rotation of the main shaft motor 4, for example, the rotation speed and the forward and reverse rotation directions, according to the control signal transmitted from the program analysis unit 12.

[0019] Similarly, the feed control unit 14 controls the operation of the feed mechanism unit 7 according to the control signal transmitted from the program analysis unit 12, for example, controls the speed (feed speed) at which the tool 8 is moved (speed control), and controls the movement position of the cutting edge of the tool 8 (position control).

[0020] Also, the parameter storage unit 15 is a functional unit that stores the values of the parameters used when the feed control unit 14 executes "G985" that defines vibration thread cutting. These data are input from the outside in advance and stored in the parameter storage unit 15. Note that the details of the parameters will be described later.

[0021] According to the machine tool 1 of this example having the above configuration, with the workpiece W held by the chuck 5, under the control of the control device 10, the main shaft motor 4 and the feed mechanism unit 7 are operated according to an appropriate NC program stored in the program storage unit 11, so that the workpiece W held by the chuck 5 is turned by the tool 8. And in this example, by the control device 10 executing "G985" that defines the above-described vibration thread cutting, thread cutting with vibration of the tool 8 in the X-axis direction is executed. Hereinafter, the specific mode of the thread cutting of this example will be described.

[0022] FIG. 1 is also an explanatory diagram for explaining the threading process of this example. In FIG. 1, the movement path (tool path) of the cutting edge of the tool 8 is shown by a broken line. As shown in FIG. 1, in the threading process of this example, after the cutting edge of the tool 8 is positioned at the starting position (Xa, Za), it moves at a predetermined feed rate to the first cutting position (X1, Za) in the X-axis direction at a predetermined cutting feed rate, and then moves to the position (X1, Z1) at the feed rate per revolution (mm / rev) corresponding to the thread pitch to perform threading on the workpiece W. Next, after moving to the relief position (Xa, Zb), it returns to the starting position (Xa, Za) to complete the first threading process. Next, while cutting the tool 8 into the workpiece W with a predetermined cutting amount, the tool 8 is moved along the same path to perform threading on the workpiece W a plurality of times (n times). In this example, as an example, six times (n = 6) of threading processes are performed. However, the number of threading processes is not limited to six times, and it may be five times or less, or conversely, seven times or more.

[0023] The tool paths for six threading processes as an example are as follows. a) First threading process (First threading) (Xa, Za) → (X1, Za) → (X1, Z1) → (Xa, Zb) → (Xa, Za) b) Second threading process (Second threading) (Xa, Za) → (X2, Za) → (X2, Z2) → (Xa, Zb) → (Xa, Za) c) Third threading process (Third threading) (Xa, Za) → (X3, Za) → (X3, Z3) → (Xa, Zb) → (Xa, Za) d) Fourth threading process (Fourth threading) (Xa, Za) → (X4, Za) → (X4, Z4) → (Xa, Zb) → (Xa, Za) e) Fifth threading process (Fifth threading) (Xa, Za) → (X5, Za) → (X5, Z5) → (Xa, Zb) → (Xa, Za) f) Sixth threading process (Sixth threading) (Xa, Za) → (X6, Za) → (X6, Z6) → (Xa, Zb) → (Xa, Za)

[0024] And at that time, in the cutting operation of moving at least the tool 8 along the Z-axis, the feed control unit 14 vibrates the tool 8 in the X-axis direction with a predetermined vibration amplitude and frequency, and a phase set with respect to the rotational phase (rotation angle) of the workpiece W.

[0025] <Mode of vibration thread cutting> Next, a thread cutting process involving vibration, which is a novel and useful process mode not disclosed in the prior art, will be described.

[0026] (First aspect) The movement path (tool path) in the radial direction (X-axis direction) of the cutting edge of the tool 8 and the axial direction (Z-axis direction) of the workpiece W in the thread cutting process according to the first aspect is shown in FIG. 3. As shown in FIG. 3, from the first thread cutting process to the fourth thread cutting process, it is a thread cutting process with vibration (vibration thread cutting process, vibration cutting cycle), and the fifth thread cutting process and the sixth thread cutting process are thread cutting processes without vibration (non-vibration thread cutting process, non-vibration cutting cycle), and a total of six thread cutting processes are performed. In FIG. 3, the vertical axis represents the position of the cutting edge of the tool 8 in the X-axis direction (radial direction), and the horizontal axis represents the position of the cutting edge of the tool 8 in the Z-axis direction (axial direction) corresponding to the rotation angle of the workpiece W.

[0027] Also, in the vibration thread cutting process from the first thread cutting process to the fourth thread cutting process, the vibration frequency, in other words, the number of vibrations per revolution of the workpiece W, is the same in each thread cutting process and is set to one in each case. Also, the phase of the vibration in each vibration thread cutting process is in the reverse phase between the preceding and succeeding vibration thread cutting processes, and the amplitude is set to a cutting amount and amplitude such that the tool paths in the preceding and succeeding vibration thread cutting processes partially intersect, that is, one peak and the other valley intersect, and one valley and the other peak intersect. Note that the phase of the vibration means the rotation angle of the workpiece W at which the vibration processing starts.

[0028] Also, as shown in FIG. 3, in this example, the depth of cut in the vibration thread cutting is defined based on the center position of the vibration amplitude of the cutting edge of the tool 8 (vibration center position). The depth of cut in the first thread cutting is defined by the distance in the radial direction between the outer peripheral surface of the workpiece W and the vibration center position of the cutting edge of the tool 8. Also, the depth of cut in each of the second to fourth thread cuttings is defined by the distance in the radial direction between the vibration center positions of the cutting edges of the tool 8 in the preceding and succeeding processes. And the depth of cut in the fifth thread cutting is the distance in the radial direction between the vibration center position of the cutting edge of the tool 8 during the fourth thread cutting and the position of the cutting edge of the tool 8 during the fifth thread cutting, and the depth of cut in the sixth thread cutting is the distance in the radial direction between the position of the cutting edge of the tool 8 during the fifth thread cutting and the position of the cutting edge of the tool 8 during the sixth thread cutting. Note that the definition of the depth of cut in the vibration thread cutting is not limited to this example, and for example, it may be defined based on the position of the cutting edge of the tool 8 at the vibration valley.

[0029] In this first aspect, as described above, in each of the first (first pass) to fourth (fourth pass) thread cuttings, the tool paths partially intersect with each other in the front and back, that is, one crest and the other trough overlap, and one trough and the other crest overlap. By overlapping the tool paths in this way, the chips are surely separated.

[0030] Furthermore, the degree of overlap between the front and rear tool paths does not necessarily have to be constant and can be set to different overlaps for each threading operation. Also, the amplitude in each vibrating threading operation may be constant, but can be different, and preferably can be an amplitude corresponding to the depth of cut. For example, as in this example, by gradually decreasing the amplitude from the first threading operation to the fourth threading operation, while achieving chip breaking, the cutting load can be gradually reduced. Similarly, the depth of cut in each vibrating threading operation may be constant, but the depth of cut may be gradually reduced as the threading operation progresses. By gradually reducing the depth of cut, the cutting load is gradually reduced, and the dimensional accuracy and surface accuracy of the machining can be improved. And by reducing the cutting load, the load applied to the spindle motor 4 and the feed mechanism 7 of the machine tool 1 can be reduced.

[0031] On the other hand, in the fifth threading operation and the sixth threading operation, since the tool 8 is not vibrated, the machined surface (thread groove surface) of the workpiece W by the tool 8 can be finished to have good dimensional accuracy and surface accuracy. Incidentally, the fifth threading operation and the sixth threading operation, which are turning operations without this vibration, are finishing threading operations (finishing turning cycles as non-vibrating turning cycles), and it is preferable to execute this finishing threading operation two or more times for the purpose of improving dimensional accuracy and surface accuracy. Also, in the fifth threading operation, which is a non-vibrating threading operation after the fourth threading operation, which is the last vibrating threading operation, it is preferable that the tool path overlaps with the trough of the tool path during the fourth threading operation, that is, is set to contact or intersect with the trough. Also, in the last finishing threading operation, the depth of cut can be set to zero. Also, in this first aspect, it is also possible to adopt a mode in which one non-vibrating cutting cycle is executed after one vibrating cutting cycle is executed. Also in this case, the tool path during the vibrating cutting cycle and the tool path during the non-vibrating cutting cycle are set to overlap at least partially.

[0032] An example of an NC program for performing threading according to this first aspect is shown in FIG. 4. This NC program is an excerpt of some blocks related to threading and constitutes a part of an NC program including other machining. In FIG. 4, the first block describes that it is chip breaking machining (vibration machining) (CHIP BREAKING), and the next block describes that it is external diameter machining (EXTERNAL TOOL) and threading (THREAD AREA).

[0033] This NC program corresponds to the tool path described above, and six threading operations from the first threading to the sixth threading are performed. "G985" is a code for defining vibration machining, "A10" is a code for defining enabling vibration machining, and "A30" is a code for defining disabling vibration machining. When "G985" and "A10" are executed, the vibration machining command becomes effective, and when "G985" and "A30" are executed, the vibration machining command becomes ineffective (cancelled).

[0034] Also, "S_" is an NC code for defining the rotational speed of the spindle, "F_" is an NC code for defining the feed rate of tool 8, and "V_" is an NC code for defining the execution, non-execution, and vibration direction of vibration. Also, "I_" is an NC code for defining the frequency magnification of the vibration operation, and "K_" is an NC code for defining the amplitude magnification of vibration. Also, the feed rate commanded by the F code corresponds to one pitch of the thread.

[0035] Here, the frequency multiplication factor I is a parameter that defines the number of vibrations of the tool 8 during one rotation of the workpiece W. The frequency multiplication factor I corresponds to the set chip length. In the example described above, I = 1.0. Also, the amplitude multiplication factor K is the ratio of the total amplitude of the vibration operation to the depth of cut (= total amplitude / depth of cut). The feed control unit 14 controls the feed mechanism unit 7 according to the values of these parameters. Incidentally, regarding the phases of the first threading process to the fourth threading process (vibratory threading process), they are stored as parameters in the parameter storage unit 15. In this example, parameter values are stored such that the phases are in opposite phases in the front and rear vibratory threading processes.

[0036] (Second aspect) Next, the threading process according to the second aspect will be described. The movement paths (tool paths) in the radial direction (X-axis direction) of the cutting edge of the tool 8 and the axial direction (Z-axis direction) of the workpiece W in the threading process of this aspect are shown in FIG. 5. As shown in FIG. 5, in the threading process of this aspect, it is an aspect of alternately repeating a threading process with vibration in the X-axis direction (vibratory threading process, vibratory turning cycle) and a threading process without vibration (non-vibratory threading process, non-vibratory turning cycle), and a total of nine threading processes are executed.

[0037] Specifically, the first threading process, the third threading process, the fifth threading process, and the seventh threading process are vibratory threading processes (vibratory turning cycles), and the second threading process, the fourth threading process, the sixth threading process, and the eighth threading process are non-vibratory threading processes (non-vibratory turning cycles). Also, after the eighth threading process, the ninth threading process, which is a non-vibratory threading process (non-vibratory turning cycle), is repeatedly executed. Incidentally, also in FIG. 5, similar to FIG. 3, the vertical axis represents the position of the cutting edge of the tool 8 in the X-axis direction (radial direction), and the horizontal axis represents the position of the cutting edge of the tool 8 in the Z-axis direction (axial direction) corresponding to the rotation angle of the workpiece W.

[0038] In each of the first threading process, the third threading process, the fifth threading process, and the seventh threading process, the vibration frequency, that is, the number of vibrations per one rotation of the workpiece W, is the same and is set to one time for each. Also, the phases of the vibrations in each of the vibration threading processes are the same phase.

[0039] Further, the amplitudes in each of the vibration threading processes are set to gradually decrease, and the tool paths in the front and rear threading processes partially overlap, that is, the valley portion of the previous vibration threading process and the subsequent non-vibration threading process overlap, and the peak portion of the previous non-vibration threading process and the subsequent vibration threading process overlap. However, this is just an example, the vibration amplitude is arbitrary, the overlap of the tool paths in the front and rear threading processes is also arbitrary, and the overlapping modes include the contacting mode.

[0040] Also in this example, the cutting amount in the vibration threading process is defined based on the center position of the vibration amplitude of the cutting edge of the tool 8 (vibration center position). Therefore, the cutting amount of the first threading process is defined by the radial distance between the outer peripheral surface of the workpiece W and the vibration center position of the cutting edge of the tool 8. Further, the cutting amount between the vibration threading process and the non-vibration threading process is defined by the radial distance between the vibration center position of the cutting edge of the tool 8 in the vibration threading process and the position of the cutting edge of the tool 8 in the non-vibration threading process. Note that the definition of the cutting amount in the vibration threading process is not limited to this example, and it may be defined based on the cutting edge position of the tool 8 at the vibration valley.

[0041] In this second aspect, as described above, the tool paths in the front and rear threading processes partially overlap, that is, the valley portion of the previous vibration threading process and the subsequent non-vibration threading process overlap, and the peak portion of the previous non-vibration threading process and the subsequent vibration threading process overlap. Therefore, during each threading process, the chips are surely separated at the overlapping portion of the tool paths.

[0042] The degree of overlap between the tool paths before and after does not necessarily have to be constant, and can be set to different overlaps for each threading process. Alternatively, the tool paths can be made not to overlap between the vibrating threading process and the non-vibrating threading process. Even in this case, since the thickness of the chips at the part where the mutual tool paths approach is thinner (minimum) than the thickness of the chips at other parts, depending on the material of the workpiece W and the shape of the tool, it is possible to break the chips at that part.

[0043] Also, as described above, the amplitude in each vibrating threading process may be constant, but can be made different amplitudes, and preferably, can be an amplitude corresponding to the depth of cut. For example, as in this example, by gradually reducing the amplitude in the order of the first threading process, the third threading process, the fifth threading process, and the seventh threading process, while realizing chip breaking, the cutting load can be gradually reduced. Also, the depth of cut in each vibrating threading process may be constant, but it is preferable to gradually reduce the depth of cut as the machining progresses. Similarly, the depth of cut in the non-vibrating threading process may be constant, but it is preferable to gradually reduce the depth of cut as the machining progresses. By gradually reducing the depth of cut, the cutting load is gradually reduced, and the dimensional accuracy and surface accuracy of the machining can be improved. And by reducing the cutting load, the load applied to the spindle motor 4 and the feed mechanism 7 of the machine tool 1 can be reduced.

[0044] On the other hand, since the second-to-last eighth threading process and the final ninth threading process are non-vibrating threading processes as finishing threading processes, the machined surface (thread groove surface) of the workpiece W by the tool 8 can be finished to have good dimensional accuracy and surface accuracy. Incidentally, it is preferable to perform this finishing threading process two or more times for the purpose of improving the dimensional accuracy and surface accuracy. In the last finishing threading process, the depth of cut may be set to zero.

[0045] An example of an NC program for performing the threading process according to this second aspect is shown in FIG. 6. This NC program is also an excerpt of some blocks related to the threading process and constitutes a part of the NC program including other processes. In FIG. 6, it is described in the first block that it is a chip breaking process (vibration process) (CHIP BREAKING), and in the next block, it is described that it is an external diameter process (EXTERNAL TOOL) and a threading process (THREAD AREA).

[0046] This NC program corresponds to the tool path described above, and nine threading processes from the first threading process to the ninth threading process are executed. Incidentally, each NC code and each parameter in the vibration threading process are as described above. Incidentally, regarding the phase in each vibration threading process, it is stored as a parameter in the parameter storage unit 15, and in this example, the value of the parameter is stored such that the phases in each vibration threading process are in the same phase.

[0047] <Creation of NC Program> The NC program for performing the vibration threading process can be created, for example, by the second control device 40 provided in the machine tool 1 as shown in FIG. 7. Hereinafter, this aspect will be described.

[0048] The machine tool 1 shown in FIG. 7 includes an operation panel 30 and a second control device 40 in addition to the above configuration. As described above, the control device 10 stores a storage unit (program storage unit 11 and parameter storage unit 15) for storing programs for executing (interpreting) the NC program and controlling the main spindle drive unit (main spindle motor) 4 and the feed mechanism unit 7, and a drive control unit (program analysis unit 12, main spindle control unit 13, feed control unit 14) for executing the NC program and controlling the main spindle drive unit (main spindle motor) 4 and the feed mechanism unit 7.

[0049] The operation panel 30 is provided with a program execution button 31 and a display unit 32 (for example, a touch panel) that displays programs and information about the machine tool (such as coordinates). The operator can perform various operations related to machining and create NC programs while checking the display on the display unit 32 on the operation panel 30.

[0050] When the program execution button 31 on the operation panel 30 of the machine tool 1 is pressed, the program analysis unit 12 executes the NC program. That is, the program analysis unit 12 reads the NC program stored in the program storage unit 11, and based on the read NC program, transmits control signals to the spindle control unit 13 and the feed control unit 14 respectively. According to these control signals, the spindle control unit 13 controls the spindle motor 4, and the feed control unit 14 controls the feed mechanism unit 7. And thus, machining is executed.

[0051] The second control device 40 includes a storage unit 42 that stores programs for controlling the display on the screen of the operation panel 30, a display control unit 41 that has an OS for operating the program, and a programming unit 43.

[0052] The storage unit 42 stores programs for screen display on the display unit 32, programs for data input via the display screen, and data such as the format of the display screen. The display control unit 41 performs screen display on the display unit 32 while operating these programs and controls the input of data via the display screen. The second control device 40 processes and executes these storage functions and display control functions by arithmetic means such as a CPU or LSI different from the arithmetic means of the control device 10. In particular, the storage unit 42 stores format data for displaying the input screen 35 for creating the NC program shown in FIG. 8. When a request signal for creating an NC program is input from the input screen displayed on the display unit 32 of the operation panel 30 and received from the operation panel 30 via the display unit 32, the display control unit 41 displays the input screen 35 on the display unit 32 based on the format data stored in the storage unit 42.

[0053] When appropriate data is input via the input screen 35 displayed on the display unit 32, the programming unit 43 creates an NC program based on the input data. Then, the programming unit 43 transmits the created NC program to the control device 10 and stores it in the program storage unit 11.

[0054] The input screen 35 shown in FIG. 8 is an input screen capable of creating an NC program for performing a process of vibrating the tool 8 in the radial direction in the external diameter threading process. For example, select "General External Diameter" in the column of the tool name 35a, select "Thread" in the column of the process 35b, select "Automatic Calculation" in the column of the depth of cut 35g, select "Thread Area" in the column of the area designation 35m, and select "Effective" in the column of the chip breaking 35o. Also, for example, select "7" in the column of the number of cutting passes 35r, select "NORMAL" in the column of the chip length 35s, select "Automatic Calculation" in the column of the thread outer diameter and root diameter 35t, and select "Automatic Calculation" in the column of the thread pitch 35u. Then, appropriately set the column 35v of the moving position of the tool. By making these settings, in the external diameter threading process, an NC program for vibrating the tool 8 in the radial direction can be created. Note that the chip length can be set in three levels: "NORMAL", "SHORT", and "VERY SHORT". The above-described frequency multiplier I corresponds to the set chip length. For example, when the chip length is "NORMAL", I = 0.5; when the chip length is "SHORT", I = 1.5; and when the chip length is "VERY SHORT", I = 2.5.

[0055] When the necessary information is input on the input screen 35 and the NC program button 35z is pressed, the programming unit 43 creates an NC program as shown in FIGS. 4 and 6 based on the above-described information and other information input from the input screen 35. Although detailed description is omitted, in FIG. 8, the above-mentioned other input fields are respectively labeled with reference numerals 35c, 35d, 35e, 35f, 35h, 35i, 35j, 35k, 35l, 35n, 35p, 35q. Also, an image diagram of the vibrating threading process is displayed in the display area 35w, and information about the chip length is displayed in the display area 35x.

[0056] In this way, the programming unit 43 creates an NC program based on the data input via the input screen 35 displayed on the display unit 32, transmits the created NC program to the control device 10, and stores it in the program storage unit 11 thereof. Then, when the operator selects the program created on the operation panel 30 and presses the program execution button 31 provided on the operation panel 30, the control device 10 that has received the input from the operation panel 30 executes the NC program.

[0057] Note that, in the example shown in FIG. 7, the second control device 40 as the program creation device is provided inside the machine tool 1, but a configuration similar to that of the second control device 40 may be provided outside the machine tool 1.

[0058] As described above, specific embodiments of the present invention have been described. However, the above-described embodiments are illustrative in all respects and not restrictive. Modifications and changes are appropriately possible for those skilled in the art. The scope of the present invention is indicated not by the above-described embodiments but by the scope of the claims. Further, the scope of the present invention includes modifications from the embodiments within the scope equivalent to the scope of the claims.

Explanation of Reference Numerals

[0059] 1 Machine tool 2 Spindle headstock 3 Spindle 4 Spindle motor 5 Chuck 6 Tool turret 7 Feed mechanism unit 8 Tool 10 Control device 11 Program storage unit 12 Program analysis unit 13 Spindle control unit 14 Feed control unit 15 Parameter storage unit

Claims

1. A machine tool comprising a tool holding part for holding a tool for machining a workpiece, a workpiece holding part for holding the workpiece, a rotational drive part for rotating the workpiece holding part about an axis center, a feed mechanism part for relatively moving the workpiece holding part and the tool holding part in a direction along the axis and a direction orthogonal to the axis, and a control part for controlling the rotational drive part and the feed mechanism part according to an NC program, wherein the control part, under control based on the NC program, moves the workpiece holding part holding the workpiece and the tool holding part holding the tool in the X-axis direction orthogonal to the axis to cause the tool to cut into the workpiece, and then moves in the Z-axis direction parallel to the axis to perform a turning operation for turning the workpiece. In the turning operation, the machine tool is configured to perform a vibration operation of advancing and retreating at a predetermined frequency in the X-axis direction while performing a feed operation of moving along the Z-axis direction. The control unit is configured to: execute a vibration turning cycle in which a turning operation with the vibration operation is performed after the cutting operation, and after executing the vibration turning cycle, execute a non-vibration turning cycle which is a turning operation without the vibration operation. In the non-vibration turning cycle after the vibration turning cycle, the movement locus of the tool in the non-vibration turning cycle is configured to overlap at least partially with the movement locus of the tool in the previous vibration turning cycle.

2. The control unit is configured to: execute the vibration turning cycle a plurality of times repeatedly, and between the vibration turning cycle and the vibration cutting cycle, execute at least one non-vibration turning cycle without the vibration operation. The machine tool according to Claim 1 is configured in this way.

3. A tool holding part for holding a tool for machining a workpiece, a workpiece holding part for holding the workpiece, a rotation driving part for rotating the workpiece holding part about the axis center, a feed mechanism part for relatively moving the workpiece holding part and the tool holding part in a direction along the axis and a direction orthogonal to the axis, and a control part for controlling the rotation driving part and the feed mechanism part according to an NC program, wherein the control part, under the control based on the NC program, moves the workpiece holding part holding the workpiece and the tool holding part holding the tool in the X-axis direction orthogonal to the axis to perform a cutting operation of cutting the tool into the workpiece, and then moves in the Z-axis direction parallel to the axis to perform a turning operation of turning the workpiece. In the turning operation, a feed operation of moving along the Z-axis direction is performed while a vibration operation of advancing and retreating at a predetermined frequency in the X-axis direction is performed. A machine tool configured as follows: The control unit is A machine tool configured to alternately repeat, one or more times each, a vibration turning cycle in which a turning operation accompanied by the vibration operation is performed after the cutting operation, and a non-vibration turning cycle in which a turning operation not accompanied by the vibration operation is performed after the cutting operation.

4. The control unit is The machine tool according to claim 3, wherein in the non-vibration turning cycle executed after the vibration turning cycle, the movement locus of the tool in the turning operation is operated so as to overlap at least partially with the movement locus of the tool in the vibration operation of the immediately preceding vibration turning cycle.

5. The control unit is The machine tool according to claim 3, wherein the vibration turning cycle and the non-vibration turning cycle are alternately repeated a plurality of times each, and in the vibration turning cycles before and after, the phase of the vibration operation with respect to the rotation phase of the workpiece is operated to be in the same phase between the vibration turning cycles before and after.

6. The control unit is The machine tool according to claim 3, wherein after the last vibration turning cycle is executed, a finish turning cycle as the non-vibration turning cycle is executed one or more times.

7. The control unit is The machine tool according to claim 6, wherein in the finish cutting cycle, in the last finish cutting cycle, the cutting operation is not performed, and in the finish cutting cycle before that, the cutting operation is performed.

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