Machine tool and workpiece machining method

Abstract

To provide a machine tool capable of inhibiting occurrence of an event that a workpiece whose top cutting has not been properly performed is processed.SOLUTION: A PU 52 uses a cut-off tool breakage detector to determine prior to top cutting whether a workpiece W exists within a predetermined area A. When the workpiece W exists within the predetermined area A, the PU 52 executes top cutting. When no workpiece W exists within the predetermined area A, the PU 52 determines a distribution abnormality of the workpiece W.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a machine tool and a method for machining a workpiece.

Background Art

[0002] For example, Patent Document 1 below describes an apparatus for supplying a bar-shaped workpiece to the spindle of a NC lathe. Here, in order to machinethe tip surface of the workpiece supplied to the spindle with high precision, it is necessary to position the tip with high precision.

[0003] Therefore, conventionally, each time a new workpiece is supplied to the spindle, a top cut process is executed. The top cut process is a process of removing the tip of the workpiece with a parting tool. Thereby, the position of the tip of the removed workpiece can be grasped with high precision.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, if a large error occurs when supplying the workpiece, there is a risk that the tip of the workpiece will not be removed by the parting tool in the top cut process. And in that case, the positioning accuracy of the tip surface of the workpiece decreases.

Means for Solving the Problems

[0006] Hereinafter, means for solving the above problems and their effects will be described. 1. The machine tool comprises a spindle, a cutting unit, a sensor, and a control device, wherein the spindle is a device that rotates a rod-shaped workpiece around the axis of rotation of the workpiece, the cutting unit cuts the workpiece with a plane perpendicular to the axis as the cutting surface, the sensor is a sensor that detects objects present in the area located at the cutting point when the cutting unit cuts the workpiece, and the control device is configured to perform abnormality detection processing before the top cut process of the workpiece, and the abnormality detection processing includes a process that determines, based on the detected value of the sensor, that if it is determined that no object is present in the area located there, it is an abnormality that the setup for performing the top cut process is not ready.

[0007] The top-cut process is performed with the workpiece positioned so that it is located in the area described above. Therefore, by detecting whether or not an object is present in the area described above using sensors through an anomaly detection process before the top-cut process, it is possible to determine whether or not there is an anomaly where the setup for the top-cut process is not complete. This prevents situations where workpieces that have not undergone the top-cut process properly are processed.

[0008] Note that "before the top-cutting process" also includes "during the top-cutting process." 2. The control device is configured to perform a retry process, the retry process being a process of displacing the workpiece by a predetermined amount in a predetermined direction when the abnormality detection process determines that there is an abnormality, the predetermined direction being a direction in which the workpiece is displaced to approach the region in which it is located prior to being cut by the cutting unit, and the abnormality detection process being the machine tool described in 1 above, which includes a process of determining again whether or not the object exists based on the detected value of the sensor after the retry process.

[0009] In the above configuration, by performing a retry process, the workpiece position can be corrected if the workpiece position is unsuitable for the top-cutting process. Furthermore, compared to a control system that stops the machine equipped with the cutting unit and spindle when an abnormality occurs, performing a retry process has the following effect: In other words, when continuous workpiece processing is being performed unattended, even at night, it can prevent the entire production process from being shut down.

[0010] 3. The control device is configured to perform a retry count acceptance process, the retry count acceptance process is a process that accepts the number of retries from the user via an interface, the number of retries is the upper limit number of repetitions of the abnormality detection process and the retry process, and the control device is configured to repeat the retry process up to the upper limit of the number of retries until the abnormality detection process determines that there is no abnormality, as described in item 2 above.

[0011] In the above configuration, the retry count acceptance process allows the number of retries to be set to a value that aligns with the user's preference. 4. The control device is configured to perform a displacement amount receiving process, the displacement amount receiving process is a process that receives a predetermined amount from the user via an interface to displace the workpiece by the retry process, and the retry process is a machine tool according to 2 or 3 above, which includes a process that displaces the workpiece by the predetermined amount received by the displacement amount receiving process.

[0012] In the above configuration, the displacement amount acceptance process allows the predetermined amount by which the workpiece is displaced during the retry process to be set to a value that meets the user's requirements. 5. The control device is configured to perform abnormality processing, and the abnormality processing includes, if the abnormality detection processing determines that there is an abnormality after the completion of the retry processing, issuing a warning and stopping the machine equipped with the cutting unit and the spindle, as described in any one of 2 to 4 above.

[0013] In the above configuration, if an abnormality is detected even after the retry process, a warning is issued to allow the user to understand the situation. In addition, stopping the processing machine can prevent the execution of inappropriate processing.

[0014] 6. The cutting unit is equipped with a parting tool, the sensor is a sensor that senses an object present in the area where the parting tool is located when cutting the workpiece, the control device is configured to perform a parting tool breakage detection process, and the parting tool breakage detection process includes a process that determines that the parting tool is broken if the sensor detects the presence of the object in the area where it is located after the completion of the parting process of the workpiece. This is the machine tool according to any one of 1 to 5 above.

[0015] In the above configuration, since the sensor used for detecting damage to a parting tool can be reused to perform the anomaly detection process, it is possible to avoid installing a new sensor specifically for the anomaly detection process. 7. The control device is configured to allow a user to input a machining program via an interface and comprises an execution device and a storage device, the storage device storing a plurality of code data, the machining program is a command to be executed by the execution device to control a machining machine comprising the cutting unit and the spindle for machining the workpiece, and is configured by selectively combining some of the plurality of code data, the plurality of code data includes a code to cause the execution device to perform the abnormality detection process, the machine tool is as described in any one of 1 to 6 above.

[0016] In the above configuration, by including code for executing anomaly detection processing in the code data, the processing program can be made into a program that includes a command to execute anomaly detection processing.

[0017] Furthermore, multiple code data sets may include code to cause the execution device to perform a retry process. Additionally, multiple code data sets may include code to cause the execution device to perform a parting byte corruption detection process.

[0018] 8. The sensor is a machine tool according to any one of 1 to 7 above, comprising a detection body and outputting a signal according to the presence or absence of the object in the predetermined region as the detection body is displaced to the predetermined region, wherein the predetermined region is a region including the region in which the object is located.

[0019] According to the above sensor, it is possible to determine whether or not an object exists in a predetermined area. If it is determined that an object exists in the predetermined area, it is possible to determine that an object exists in the area where the cutting unit will be positioned when cutting the workpiece.

[0020] Furthermore, in the above configuration, by using a sensor that senses the presence or absence of an object within a predetermined area by displacing the detection object toward that predetermined area, the presence or absence of an object can be easily determined according to the output signal of the sensor.

[0021] Furthermore, when using this sensor, the abnormality detection process is performed prior to the top-cutting process. Incidentally, if the cutting unit is equipped with a parting tool, the sensor is equipped with a detection body and outputs a signal according to the presence or absence of the object in the predetermined region as the detection body is displaced to the predetermined region, the predetermined region is a region in which the value of the component of the first coordinate axis is greater than or equal to the value of the region in which the parting tool is located when cutting the workpiece, and the value of the component of the second coordinate axis includes the value of the component of the second coordinate axis of the workpiece, and the value of the component of the third coordinate axis includes the value of the component of the third coordinate axis of the workpiece, the first coordinate axis is an axis that encompasses the axis of the workpiece, the component of the first coordinate axis is a component in which the direction in which the workpiece is displaced to approach the parting tool prior to being processed by the parting tool is positive, and the second and third coordinate axes may be coordinate axes that are orthogonal to each other and orthogonal to the first coordinate axis.

[0022] 9. The sensor is a sensor that non-contact senses an object existing in a predetermined area, and the predetermined area is an area including the located area, and the machine tool is the machine tool according to any one of 1 to 7 above.

[0023] 10. A workpiece processing method having a step of executing each of the above processes in the machine tool according to any one of 1 to 9 above. In addition, when not including the matters described in 2 or 6 above, "each of the above processes" shall be read as "the abnormality detection process".

Brief Description of Drawings

[0024] [Figure 1] It is a diagram showing the configuration of a processing system according to an embodiment. [Figure 2] It is a diagram showing the configuration of a tool rest according to the same embodiment. [Figure 3] (a) and (b) are diagrams showing the operation of a breakage detection device for a parting tool. [Figure 4] It is a flowchart showing the processing procedure of a parting tool breakage detection code according to the same embodiment. [Figure 5] (a) to (c) are side views exemplifying the processing prior to the top cut processing. [Figure 6] (a) and (b) are side views exemplifying the top cut processing. [Figure 7] It is a flowchart showing the processing procedure of a workpiece position abnormality detection code according to the same embodiment. [Figure 8] It is a flowchart showing the procedure of parameter setting processing of a workpiece position abnormality detection code according to the same embodiment. [Figure 9] It is a flowchart showing an example of a processing procedure using a machining program according to the same embodiment. [Figure 10] It is a flowchart showing an example of a processing procedure using a machining program in a comparative example. [Figure 11](a) and (b) are diagrams showing a sensor according to a modified example of the above embodiment. [Figure 12] This figure shows a sensor according to a modified example of the above embodiment. [Figure 13] This figure shows a processing machine according to a modified example of the above embodiment. [Figure 14] This figure shows a processing machine according to a modified example of the above embodiment. [Modes for carrying out the invention]

[0025] The following describes one embodiment with reference to the drawings. "Configuration of the processing system" Figure 1 shows the configuration of the processing system according to this embodiment.

[0026] The lathe 1 shown in Figure 1 comprises a machining center 10 and a machining control device 50. The machining center 10 is a device for cutting a rod-shaped workpiece W. The machining center 10 has a spindle 14 on a bed 12. The spindle 14 is a device that rotates the workpiece W around its axis. The spindle 14 is equipped with a chuck 16 for gripping the workpiece W. The spindle 14 is displaceable in the positive and negative directions of the Z-axis as shown in Figure 1. The Z-axis is the axis that encompasses the axis of the workpiece W inserted into the spindle 14. The Z-axis extends horizontally.

[0027] The machining center 10 is equipped with a guide bush 18 that supports the workpiece W, located on the positive Z-axis side of the spindle 14. The machining center 10 is also equipped with a tool post 20. The tool post 20 is equipped with a cutting tool for machining the workpiece W that protrudes from the guide bush 18. In the figure, the tool post 20 is displaceable in the direction of the Y axis and the X axis. Here, the direction of the Y axis is horizontal and perpendicular to the direction of the Z axis. The direction of the X axis is perpendicular to the direction of the Z axis and the Y axis.

[0028] The material feeder 40 is a device that supplies the workpiece W to the processing machine 10. More specifically, the material feeder 40 is a device that inserts the workpiece W into the spindle 14 by displacing the workpiece W in the positive direction of the Z axis. The material feeder 40 is equipped with an actuator 40a that pushes the workpiece W in the positive direction of the Z axis and a tip detection sensor 40b for detecting the amount of displacement of the workpiece W.

[0029] The feeder control device 42 is a control device that operates the material feeder 40 to control the supply of workpiece W to the processing machine 10. In this process, the feeder control device 42 refers to the displacement detection result from the tip detection sensor 40b.

[0030] The machining control device 50 controls the machining machine 10. The machining control device 50 controls the values ​​of the Z-axis coordinate components of the spindle 14 and the X-axis coordinate components and Y-axis coordinate components of the tool post 20. The machining control device 50 includes a PU 52, a ROM 54, and a RAM 56. The PU 52 is a software processing unit such as a CPU, GPU, and TPU. The ROM 54 may be an electrically immutable memory. Alternatively, the ROM 54 may be an electrically rewritable non-volatile memory and a storage medium such as a disk medium.

[0031] The ROM 54 stores the control program 54a and the code data group 54b. The RAM 56 stores the machining program 56a. The code data group 54b includes multiple code data. The code data contains commands that cause the PU 52 to execute each of the various machining processes of the workpiece W using the machining machine 10, which are subdivided into different processes. The machining program 56a is a program expressed by a combination of the multiple code data included in the code data group 54b. The machining program 56a defines the processes that should be executed by the PU 52 in order for the user to machine the workpiece W as desired. The machining program 56a is input by the user through the operation of the input device 60. At this time, the PU 52 displays the machining program 56a on the display device 62. The control program 54a includes commands for the PU 52 to execute the machining program 56a, and commands to control the display device 62, etc.

[0032] "Detailed functions of a lathe" Figure 2 shows the configuration of the tool post 20. Multiple cutting tools 22(1) to 22(6) are attached to the tool post 20. In the following, when referring to cutting tools 22(1) to 22(6) collectively, they will be referred to as cutting tool 22. Cutting tool 22(1) is a parting tool. That is, cutting tool 22(1) is a cutting tool for cutting the workpiece W into two pieces. Cutting tool 22(1) is a cutting tool for cutting the workpiece W so that the cutting surface is perpendicular to the Z axis.

[0033] The tool post 20 is provided with a breakage detection device 30 for the cutting tool 22(1). The breakage detection device 30 comprises a detection rod 32, a detected object 34, a contact sensor 36, and an elastic body 38. The detection rod 32 and the detected object 34 are connected. The elastic body 38 is a member that presses the detected object 34 against the contact sensor 36. The contact sensor 36 is a sensor that outputs a signal depending on whether or not the detected object 34 is in contact. The contact sensor 36 may be, for example, an actuating transformer type sensor, an optical scale type sensor, a magnetic scale type sensor, etc.

[0034] "Detection of damage to parting tool" Figures 3(a) and 3(b) illustrate the principle of detecting corruption in byte 22(1). Figure 3(a) shows the state after the parting-off process is completed. As shown in Figure 3(a), when the parting-off process is performed normally, the tip of the workpiece W has a smaller Z-axis coordinate component than the cutting tool 22(1). In this state, when the tool post 20 is displaced in the positive Y-axis direction, the detection rod 32 does not come into contact with the workpiece W.

[0035] In contrast, Figure 3(b) shows a case where the tool post 20 is displaced in the positive direction of the Y-axis when the parting-off process is abnormal due to damage to the cutting tool 22(1). In this case, since the workpiece W comes into contact with the detection rod 32, as the tool post 20 is displaced in the positive direction of the Y-axis, the detection rod 32 is subjected to a force in the negative direction of the Y-axis. As a result, the object to be detected 34 overcomes the elastic force of the elastic body 38 and separates from the contact sensor 36.

[0036] Based on the above, the contact sensor 36 detects whether or not byte 22(1) is damaged, and whether or not it is in contact with the object to be detected 34. Figure 4 shows the procedure for the processing defined by the "parting tool breakage detection code" in the code data. The "parting tool breakage detection code" indicates a code that indicates the processing to be performed after parting is performed. The processing shown in Figure 4 is realized when PU52 executes the "parting tool breakage detection code" described in the machining program 56a according to the control program 54a. In the following, the step number of each processing is represented by a number preceded by "S".

[0037] In the series of processes shown in Figure 4, the PU 52 first displaces the tool post 20 by a specified amount ΔY in the positive direction of the Y axis (S10). This process is to cause the detection rod 32 of the damage detection device 30 to enter the predetermined region A shown in Figure 1. The components of the Z axis coordinate of the predetermined region A have values ​​greater than or equal to a predetermined value. Here, the predetermined value is the minimum value of the components of the Z axis coordinate of the byte 22(1). The width of the components of the Z axis coordinate of the predetermined region A may be, for example, 2 to 5 times or less the difference between the minimum and maximum values ​​of the components of the Z axis coordinate of the byte 22(1). Alternatively, for example, it may be 20 times or less the difference between the minimum and maximum values ​​of the components of the Z axis coordinate of the byte 22(1). The components of the Y axis coordinate of the predetermined region A include the values ​​of the components of the Y axis coordinate of the axis of the workpiece W. In particular, Figure 1 shows an example in which the components of the Y axis coordinate of the predetermined region A include all the values ​​of the components of the Y axis coordinate of the workpiece W. Furthermore, the components of the X-axis coordinate of the predetermined region A include the values ​​of the components of the X-axis coordinate of the axis of the workpiece W. In particular, Figure 1 shows an example in which the components of the X-axis coordinate of the predetermined region A encompass all the values ​​of the components of the X-axis coordinate of the workpiece W.

[0038] Next, PU52 takes the detection value from the contact sensor 36 as input and determines whether or not there is an object in the predetermined region A (S12). The state shown in Figure 3(a) is when no object is present. The state shown in Figure 3(b) is when an object is present. More precisely, the process in S12 determines whether or not there is an object in the region of the predetermined region A that the detection rod 32 can enter. The Z-axis coordinate components of the part of the detection rod 32 that enters the predetermined region A may take only a portion of the Z-axis coordinate components of the predetermined region A. If PU52 determines that an object is present in the predetermined region A (S12: YES), it determines that byte 22(1) is damaged (S14). Then, PU52 notifies the user that byte 22(1) is damaged by emitting a warning sound by operating the speaker 64 shown in Figure 1 (S16). Next, PU52 stops the processing machine 10 (S18). This cuts off the power supply to the motor that rotates the spindle 14, as well as the power supply to the actuators that displace the spindle 14 and the tool post 20.

[0039] Furthermore, when PU52 completes the process in S18, or when it makes a negative determination in the process in S12, it temporarily terminates the series of processes shown in Figure 4. "Top cut processing" The cutting tool 22(1) is also used for top-cutting. Top-cutting is a process in which the tip of a workpiece W is cut off when a new workpiece W is supplied to the processing machine 10 from the material feeder 40. This is a process for positioning the workpiece W. That is, by gripping the workpiece W with the chuck 16 and displacing the spindle 14, the amount of displacement of the workpiece W becomes the amount of displacement of the spindle 14. Therefore, the amount of displacement of the workpiece W can be determined with high precision by the amount of displacement of the spindle 14. However, due to the low accuracy of the detection of the tip of the workpiece W by the material feeder 40, it is difficult to initially determine the position of the tip of the workpiece W with high precision. Therefore, by performing top-cutting, the position of the tip of the workpiece W is determined with high precision. That is, the value of the Z-axis coordinate component of the tip of the workpiece W at the completion of top-cutting becomes the value of the Z-axis coordinate component of the cut surface by the cutting tool 22(1).

[0040] Figure 5 shows the distribution control of the workpiece W by the material feeder 40 for top cutting. Figure 5(a) shows the positional relationship of the spindle 14, etc., prior to the distribution control of the workpiece W by the material feeder 40. As shown in Figure 5(a), in this state, the components of the Z-axis coordinate of the spindle 14 are small. The distance L2 from the chuck 16 to the guide bush 18 and the distance L1 from the tip detection sensor 40b to the guide bush 18 in this state are predetermined. Therefore, the value obtained by subtracting distance L2 from distance L1 is known by the feeder control device 42.

[0041] As shown in Figure 5(b), the material feeder 40 displaces the workpiece W by a specified amount LL in the positive Z-axis direction relative to the tip detection sensor 40b. In this state, the tip of the workpiece W protrudes beyond the chuck 16 in the positive Z-axis direction. In this state, the workpiece W is gripped by the chuck 16.

[0042] Figure 5(c) shows the state after the workpiece W has been gripped by the chuck 16 and the spindle 14 has been displaced in the positive Z-axis direction. In this state, the tip of the workpiece W protrudes in the positive Z-axis direction relative to the guide bush 18. Figure 5(c) specifically illustrates the state in which the tip of the workpiece W is within a predetermined region A. Top cutting is performed in this state.

[0043] Figure 6 illustrates the top-cutting process. Figure 6(a) shows the state in which the tip of the workpiece W protrudes relative to the guide bush 18 due to the displacement of the spindle 14. Figure 6(a) is an enlarged view of a part of Figure 5(c).

[0044] Figure 6(b) shows the completion of the parting-off process. In the parting-off process, the tool post 20 is displaced in the negative direction of the X-axis, causing the cutting tool 22(1) to cut the workpiece W. Figure 6(b) shows the cut fragments Wa. At this point, the value of the Z-axis coordinate component of the position of the tip of the workpiece W is the minimum value of the Z-axis coordinate component of the cutting tool 22(1).

[0045] The top-cutting process described above cannot be performed successfully if, in the state shown in Figure 6(a), the value of the component of the Z-axis coordinate of the tip of the workpiece W is less than or equal to the minimum value of the component of the Z-axis coordinate of bit 22(1). In this embodiment, there is a code that determines whether or not the top-cutting process can be performed successfully prior to the parting-off process for the top-cutting process.

[0046] "Anomaly detection code for top-cut processing" Figure 7 shows the procedure for processing defined by the "workpiece position anomaly detection code" included in the code data group 54b. The workpiece position anomaly detection code is a code that detects whether or not the top-cut process can be performed normally prior to the top-cut process. The process shown in Figure 7 is realized when the PU 52 executes the "workpiece position anomaly detection code" described in the machining program 56a according to the control program 54a.

[0047] In the series of processes shown in Figure 7, the PU52 first displaces the tool post 20 by a specified amount ΔY in the positive direction of the Y axis (S20). This process determines whether the workpiece W is positioned in a way that allows the top-cut process to be performed normally. Next, the PU52 takes the output signal of the contact sensor 36 of the damage detection device 30 as input and determines whether an object exists in a predetermined area A (S22). If the PU52 determines that no object exists in the predetermined area A (S22: YES), it determines that there is an abnormality in the position of the workpiece W (S24). In other words, the PU52 determines that the top-cut process cannot be performed normally.

[0048] Next, PU52 increments the retry counter C by "1" (S26). The initial value of the retry counter C is zero. Then PU52 determines whether the retry counter C is equal to or greater than the number of retries Cth (S28). If PU52 determines that the number of retries is less than Cth (S28: NO), it displaces the tool post 20 by a specified amount ΔY in the negative direction of the Y axis (S30). This process moves the detection rod 32 outside the predetermined area A.

[0049] Then, PU52 displaces the workpiece W by a predetermined amount ΔZ in the positive Z-axis direction (S32). Then, PU52 returns to the process of S20. On the other hand, if PU52 determines that the retry counter C is equal to or greater than the number of retries Cth (S28: YES), it operates the speaker 64 to emit a warning sound (S34). This process notifies the user that an abnormal situation has occurred where the top-cut machining cannot be performed normally. Then PU52 stops the machining center 10 (S36). As a result, the power supply to the motor that rotates the spindle 14, as well as the power supply to the actuators that displace the spindle 14 and the tool post 20, is cut off.

[0050] Furthermore, when PU52 completes the process in S36, or when it makes a negative determination in the process in S22, it temporarily terminates the series of processes shown in Figure 7. The number of retries Cth and the predetermined amount ΔZ can be specified by the user.

[0051] Figure 8 shows the procedure for enabling the user to specify the number of retries Cth and a predetermined amount ΔZ. The process shown in Figure 8 is realized by the PU 52 executing the control program 54a whenever, for example, a predetermined condition is met.

[0052] In the series of processes shown in Figure 8, PU52 first determines whether the user has given an input specifying the value of the number of retries by operating the input device 60 (S40). If PU52 determines that an input has been given (S40: YES), it inputs the specified number of retries into the number of retries Cth (S42). On the other hand, if PU52 determines that there is no input specifying the number of retries (S40: NO), it assigns the default value Cth0 to the number of retries Cth (S44).

[0053] If PU52 completes the processes in S42 and S44, it determines whether or not there is an instruction input regarding the amount to displace the workpiece W in the retry process (S46). If PU52 determines that there is an instruction input (S46: YES), it inputs the instructed displacement amount into a predetermined amount ΔZ (S48). On the other hand, if PU52 determines that there is no instruction input (S46: NO), it substitutes the default value ΔZ0 into a predetermined amount ΔZ (S50).

[0054] Furthermore, when PU52 completes the processes in S48 and S50, it temporarily terminates the series of processes shown in Figure 8. "An example of machining process according to the machining program of this embodiment" Figure 9 shows an example of the machining process of workpiece W using the machining program 56a written using the above code. The series of processes shown in Figure 9 are realized by the PU 52 executing the commands specified by the machining program 56a in accordance with the control program 54a.

[0055] In the series of processes shown in Figure 9, the PU 52 first commands the feeder control device 42 to execute a control to supply the workpiece W to the processing machine 10 by operating the material feeder 40 (S60). Next, the PU 52 grasps the workpiece W with the chuck 16 (S62). This is expected to result in the state shown in Figure 5(b). Next, the PU 52 displaces the spindle 14 by a predetermined amount in the positive direction of the Z axis (S64). This is expected to result in the state shown in Figure 5(c).

[0056] Then, PU52 executes the process shown in Figure 7. If PU52 determines that the process in S22 is negative, it executes a top-cut process (S66). Then, PU52 operates the processing machine 10 continuously according to the processing program 56a to generate multiple processed parts from one workpiece W after the top-cut process is completed (S68). Here, for example, once the processing of the tip of the workpiece W is completed, a parting-off process is executed to cut the workpiece W at a predetermined length from the tip. Then, after the parting-off process, the parting-off process is performed on the tip of the workpiece W, and this series of steps is repeated. It is desirable that after the parting-off process is performed, a parting-off tool breakage detection process is executed according to the code specified in Figure 4.

[0057] When PU52 completes the process in S68 or the process in S36, it temporarily terminates the series of processes shown in Figure 9. "An example of machining process according to the machining program of this embodiment" Figure 10 shows an example of the machining process of workpiece W using a machining program that does not have the code shown in Figure 7. The series of processes shown in Figure 10 are realized by the PU 52 executing the commands specified by the machining program 56a in accordance with the control program 54a. For convenience, the same step numbers are assigned to the processes shown in Figure 9 in Figure 10.

[0058] In the series of processes shown in Figure 10, after completing processes S60 to S64, PU52 executes processes S66 and S68 and then terminates the series of processes shown in Figure 10. In this case, if, upon completion of the S64 process, the value of the Z-axis coordinate component of the tip of the workpiece W is smaller than the value of the Z-axis coordinate component of byte 22(1), then the workpiece W is not actually cut by byte 22(1). Therefore, the first workpiece produced by the S68 process will have a shorter axial length than intended.

[0059] Now, the operation and effects of this embodiment will be described. The code data group 54b stored in the ROM 54 of the machining control device 50 includes a code that defines the procedure shown in Figure 7. This allows the user of the machining machine 10 and the machining control device 50 to write the machining program 56a as illustrated in Figure 9. Specifically, the machining program 56a can be written which includes a command to execute a process to detect whether or not the leading edge of the workpiece W is in a predetermined area A prior to top-cut machining. Therefore, when producing multiple machined parts from a single workpiece W, even if the material feeding accuracy of the workpiece W by the material feeder 40 is low, it is possible to suppress the shortening of the dimensions of the first machined part.

[0060] <Correspondence> The correspondence between the matters in the above embodiments, etc. and the matters described in the "Means for Solving the Problems" section above is as follows. Below, the correspondence is shown for each number of the solution means described in the "Means for Solving the Problems" section. [1,9] The machine tool corresponds to the lathe 1. The cutting unit corresponds to the cutting tool 22. The sensor corresponds to the damage detection device 30. The abnormality detection process corresponds to the processing in S20 to S24. [2] The retry process corresponds to the processing in S30 and S32. The predetermined direction corresponds to the positive direction of the Z axis. [3] The retry count acceptance process corresponds to the processing in S40 and S42. [4] The displacement amount acceptance process corresponds to the processing in S46 and S48. [5] The abnormality processing corresponds to the processing in S34 and S36. [6] The parting tool damage detection process corresponds to the processing in S10 to S14. [7] The execution device corresponds to the PU 52. The storage device corresponds to the ROM 54. [8] The detection body corresponds to the detection rod 32. [9] Compatible with non-contact sensor 80.

[0061] <Other Embodiments> Furthermore, this embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0062] "Regarding the retry process" In the above embodiment, the user can set the maximum number of times the retry process is executed, known as the retry count Cth, but this is not the only option. In other words, it is not necessary to include a process for accepting the retry count.

[0063] In the above embodiment, the user can set the displacement amount "+ΔZ" of the workpiece W during the retry process, but this is not the only option. In other words, including a displacement amount acceptance process is not mandatory.

[0064] • Performing a retry is not necessarily required. "Regarding the processing of retry count requests" Figure 8 shows an example where PU52 assigns the default value Cth0 to the retry count Cth if the user does not specify the number of retries, but this is not the only example. For example, the system may be configured so that the retry process cannot be executed unless the user specifies the number of retries.

[0065] "Regarding the processing of displacement data requests" Figure 8 shows an example where, if the user does not specify the amount of displacement of the workpiece W due to the retry process, PU52 substitutes the default value ΔZ0 for a predetermined amount ΔZ, but this is not limited to this example. For example, the system may be configured so that the retry process cannot be executed unless the user specifies the amount of displacement.

[0066] "Regarding the processing when an anomaly is detected" • When a workpiece position anomaly is detected, it is not mandatory for both the S34 process and the S36 process to be executed. For example, the S34 process may be executed, but the S36 process may not be executed. Also, for example, the S36 process may be executed, but the S34 process may not be executed.

[0067] "Regarding the workpiece position anomaly detection code" The workpiece position anomaly detection code is not limited to a code that indicates a command to execute the processes S20-S24, S26-S32, and S34 and S36 as a set. For example, the code indicating the command to execute the processes S20-S24, the code indicating the command to execute the processes S26-S32, and the code indicating the command to execute the processes S34 and S36 may be separate codes. In other words, the code indicating the command to execute the workpiece position anomaly detection process, the code indicating the command to execute the retry process, and the code indicating the command to execute the error processing may be codes that the user can select separately. In this case, the code indicating the command to execute the error processing does not have to be a code specifically set up for when an anomaly in workpiece position is detected. That is, for example, if there is a code indicating a command to execute the process when damage to a parting tool is detected, as described in the section on "Parting Tool Breakage Detection Code," that code may be shared with it.

[0068] For example, the code indicating a command to perform abnormal workpiece position detection may be included in the code indicating a command to perform top-cut processing. "Regarding the parting tool breakage detection code" The parting tool breakage detection code is not limited to a code that indicates a command to execute the processes S10-S14 and S16-S18 together. For example, the code indicating the command to execute the processes S10-S14 and the code indicating the command to execute the processes S16-S18 may be separate codes. In other words, the code that executes the parting tool breakage detection process and the code indicating the command to execute the process when parting tool breakage is detected may be separate codes that the user can select individually.

[0069] For example, code that performs damage detection processing for parting bits may be included in the code that performs processing using parting bits. "About Code Data" It is not mandatory for the code data to include both a parting tool breakage detection code or multiple codes that constitute such a code, and a workpiece position anomaly detection code or multiple codes that constitute such a code. For example, as described in the "About Sensors" section below, if a dedicated sensor is used for workpiece position anomalies, it is not necessary to include a parting tool breakage detection code.

[0070] It is not essential that the control device executes a machining program generated by a combination of code data. For example, it may be a dedicated control device that executes a series of processes to machine the workpiece W according to a predetermined process. Even in that case, it is effective to perform workpiece position abnormality detection processing prior to the top cut process.

[0071] "About the detected substance" The detection object is not limited to the detection rod 32 shown in Figure 2, etc. For example, the cylinder 70 shown in Figure 11 may also be used. Figure 11(a) shows the case where the workpiece W is in a predetermined area A. Figure 11(b) shows the case where the workpiece W is not in the predetermined area A. The sensor using the cylinder 70 may be, for example, a reed switch. In other words, it may be a magnetic cylinder position detection sensor.

[0072] "About the sensor" The sensor that detects objects in the predetermined area A is not limited to the damage detection device 30. For example, a device with the same structure as the damage detection device 30 shown in Figure 2 may be provided as a device used only for detecting abnormal position of the workpiece W prior to the top-cut process.

[0073] The sensor that detects an object in the area located at the cutting point when the cutting unit cuts the workpiece W is not limited to a sensor that detects whether or not the detection body comes into contact with an object by displacing the detection body toward a predetermined area A. For example, as shown in Figure 12, it may be a non-contact sensor 80 that detects whether or not an object is present in the predetermined area A without contact. The non-contact sensor 80 can be placed outside the predetermined area A. As shown in Figure 12, the non-contact sensor 80 detects the presence of the workpiece W when there is a gap δ between the non-contact sensor 80 and the workpiece W.

[0074] If the workpiece W is metal, the non-contact sensor 80 may include, for example, a sensor coil. In this case, eddy currents are generated in the workpiece W by generating a high-frequency magnetic flux in the sensor coil. The magnitude of the eddy currents depends on the distance between the sensor coil and the workpiece W. Since the impedance of the sensor coil changes according to the magnitude of the eddy currents, the position relative to the workpiece W can be detected by detecting this impedance. Therefore, it is possible to determine whether or not the workpiece is in a predetermined area A. Note that the non-contact sensor 80 is not limited to this. For example, the non-contact sensor 80 may be a laser displacement meter. Also, for example, the non-contact sensor 80 may be a proximity sensor.

[0075] In the above embodiments and their modifications, examples were shown in which the sensor is attached to the tool post 20, but this is not the only example. The sensor that detects objects in the area located at the cutting point when the cutting unit cuts the workpiece W is not limited to the sensors exemplified in the above embodiment and the above modification example. For example, it may be a sensor that detects the load applied to the cutting tool 22(1) in conjunction with the top cut process. This sensor can be configured, for example, by detecting the load applied to the tool post 20 when the tool post 20 is displaced. Here, if the displacement speed of the tool post 20 is controlled to a predetermined speed by a motor, the motor current indicates the load. Also, if the tool post 20 is displaced by applying a predetermined voltage to the motor, the displacement speed or current indicates the load. Another example is a sensor equipped with a rear spindle that contacts the tip of the workpiece W, which detects whether or not torque is transmitted between the spindle 14 and the rear spindle. In this case, the position of the workpiece W is considered normal if torque is transmitted.

[0076] "About the cutting unit" The cutting unit does not necessarily have to be a cutting tool 22. For example, it may be a laser processing machine 90, as shown in Figure 13. In Figure 13, the laser processing machine 90 comprises a laser nozzle 92, a focusing system 94, and an oscillator 96. Electromagnetic waves of a predetermined frequency output from the oscillator 96 are output as laser light Le from the laser nozzle 92 via the focusing system 94. Alternatively, for example, it may be a water jet processing machine 100, as shown in Figure 14. The water jet processing machine 100 comprises a water jet nozzle 102, a water jet head 104, and a high-pressure pump 106. High-pressure liquid output from the high-pressure pump 106 is output from the water jet nozzle 102 to the workpiece W via the water jet head 104.

[0077] "Regarding the execution device" The execution device is not limited to one that executes software processing. For example, it may include a dedicated hardware circuit, such as an ASIC, that executes at least a part of the processing performed in the above embodiment. That is, the execution device may include a processing circuit having any of the following configurations (a) to (c): (a) A processing circuit comprising a processing unit that executes all of the above processing according to a program, and a program storage device such as a memory device that stores the program. (b) A processing circuit comprising a processing unit and a program storage device that execute a part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) A processing circuit comprising a dedicated hardware circuit that executes all of the above processing. Here, there may be multiple software execution devices comprising a processing unit and a program storage device. Also, there may be multiple dedicated hardware circuits.

[0078] "Regarding control devices" It is not necessary for the feeder control device 42 and the processing control device 50 to be separate units. They may be integrated into one unit.

[0079] "Other" For example, it is not essential that the device storing the control program 54a and the device storing the code data group 54b be the same. Also, for example, it is not essential that the device storing the control program 54a and the code data group 54b and the device storing the machining program 56a are different devices. [Explanation of Symbols]

[0080] 1 ... Lathe 10…Processing machine 12... Bed 14...Spindle 16... Chuck 18… Guide bush 20…Tool rest 22...bytes 30... Damage detection device 32...Detection rod 34...Detected object 36... Contact sensor 38...Elastic body 40…Material feeding machine 40a… Actuator 40b…Front detection sensor 42...Feeder control device 50… Machining control device

Claims

1. It comprises a spindle, a cutting unit, a sensor, and a control device. The aforementioned spindle is a device that rotates a rod-shaped workpiece around the axis of rotation of the workpiece. The cutting unit cuts the workpiece using a plane perpendicular to the axis as the cutting plane, The aforementioned sensor is a sensor that detects the workpiece in the region located at the cutting point when the cutting unit cuts the workpiece, The control device is configured to perform abnormality detection processing before the top cutting process of the workpiece. The abnormality detection process includes a process that determines, based on the detected value of the sensor, that if the workpiece is not present in the area where it is located, it indicates a workpiece supply abnormality in which the setup for the top-cut process is not complete.

2. The control device is configured to perform a retry process, The retry process is a process that displaces the workpiece by a predetermined amount in a predetermined direction when the anomaly detection process determines that there is an anomaly in the supply. The predetermined direction is the direction in which the workpiece is displaced to approach the region in which it is located prior to being cut by the cutting unit. The machine tool according to claim 1, wherein the abnormality detection process includes, after the retry process, a process of determining again whether or not the workpiece exists based on the value detected by the sensor.

3. The control device is configured to perform a retry count acceptance process, The aforementioned retry count acceptance process is a process that accepts the number of retries from the user via an interface. The number of retries is the upper limit on the number of repetitions of the anomaly detection process and the retry process. The machine tool according to claim 2, wherein the control device is configured to repeat the retry process up to the number of retries until the abnormality detection process determines that there is no supply abnormality.

4. The control device is configured to perform displacement amount reception processing, The displacement amount receiving process is a process that receives a predetermined amount from the user via an interface to displace the workpiece by the retry process, The machine tool according to claim 2, wherein the retry process includes a process of displacing the workpiece by the predetermined amount received by the displacement amount receiving process.

5. The control device is configured to perform abnormality processing, The machine tool according to claim 2, wherein the abnormality handling includes, if the abnormality detection handling determines after the completion of the retry handling that there is a supply abnormality, issuing a warning and stopping the machine tool equipped with the cutting unit and the spindle.

6. The cutting unit is equipped with a parting bit, The aforementioned sensor is a sensor that senses the workpiece located in the region where the parting tool is positioned when cutting the workpiece. The control device is configured to perform parting tool breakage detection processing, The machine tool according to claim 1, wherein the parting tool breakage detection process includes a process of determining that the parting tool has broken if the sensor detects that the workpiece is present in the area where it is located after the completion of the parting process of the workpiece.

7. The control device is configured to allow the user to input a machining program via an interface and includes an execution device and a storage device. Multiple code data are stored in the aforementioned storage device. The machining program is a command to be executed by the execution device in order to control a machining machine equipped with the cutting unit and the spindle for machining the workpiece, and is composed of selectively combining some of the plurality of code data. The machine tool according to claim 1, wherein the plurality of code data includes code for causing the execution device to perform the abnormality detection process.

8. The sensor is equipped with a detection body and outputs a signal corresponding to the presence or absence of the workpiece in the predetermined region due to the displacement of the detection body to the predetermined region. The machine tool according to claim 1, wherein the predetermined region is a region that includes the region in which the region is located.

9. The aforementioned sensor is a non-contact sensor that detects a workpiece located in a predetermined area. The machine tool according to claim 1, wherein the predetermined region is a region that includes the region in which the region is located.

10. A method for machining a workpiece, comprising the step of performing each of the above processes in a machine tool according to claim 2.

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