Numerical control device

Abstract

Numerical control device comprising: an estimation unit for estimating the quantity of accumulating chips produced when a tool mounted on a machine tool machined a workpiece, based on a machining condition for machining the workpiece with the tool and based on a value of a current to be supplied to a motor to move a shaft of the machine tool when the workpiece is machined with the tool; and A correction unit for correcting the amount of accumulating chips estimated by the estimating unit based on a machining mode that specifies a shape of chips produced during machining of the workpiece by the tool.

Description

Area

[0001] The present invention relates to a numerical control device that controls a machine tool. background

[0002] A machine tool performs machining operations on a workpiece to be machined according to a control provided by a numerical control device. Specifically, a tool is mounted on the machine tool, and a mechanism for moving the tool within the machine tool operates according to the control provided by the numerical control device so that the position of the tool is moved to perform machining of the workpiece. The machine tool is, for example, a lathe or a machining center. The workpiece is made of metal, for example.

[0003] Chips are generated during the machining of a workpiece. Since chips that become trapped in the tool and / or the workpiece can lead to reduced cutting accuracy, damage to the tool, or an error message caused by the increased stress, the chips that accumulate in a container on the machine tool must be removed regularly.

[0004] The prior art proposes a chip removal device having a chip conveying device in which the position of the chip ejection side is lower than the position of the chip receiving side (see, for example, Patent Document 1). Furthermore, the prior art proposes a machining system in which the amount of accumulating chips is estimated based on a machining program, and the chips are collected by a robot when the estimated amount of accumulating chips reaches a predetermined amount (see, for example, Patent Document 2). List of citationsPatent literature Patent Document 1: Japanese Patent Application Laid-Open No. 2016-221662 Patent Document 2: Japanese Patent Application Laid-Open No. 2016-168661 Short descriptionTechnical problem

[0005] However, the aforementioned chip removal device incorporates a chip conveyor, which makes it relatively large, which poses a problem. The aforementioned machining system requires an additional robot, which requires space for installation, so it is relatively large, which poses a problem. When the installation space for a machine tool is limited, the use of a chip conveyor or robot is difficult.

[0006] If a chip conveyor and robot cannot be used, the generated chip volume must be checked by an operator. If the amount of chips accumulated in a hopper of a machine tool is relatively small and the chips do not need to be removed from the hopper, the operator's labor to check the generated chip volume is wasted. However, if the operator fails to check the generated chip volume, the chips will fall out of the overfilled hopper and may lead to a reduction in cutting accuracy, damage to the tool, or an error message. The volume of long chips is generally larger than that of short chips because long chips often have gaps. This means that the generated chip volume depends on the shape of the chips.There is a need for a device that assists an operator in disposing of chips at the appropriate time without requiring an additional chip removal device on the machine tool.

[0007] The present invention has been made in view of the above, and an object thereof is to provide a numerical control device that assists an operator in disposing of chips at an appropriate time. Solution to the problem

[0008] To solve the above-mentioned problems and to achieve the object, the present invention comprises an estimation unit that estimates an amount of accumulated chips generated when a tool mounted on a machine tool cuts a workpiece, based on a machining condition when the tool cuts the workpiece and a value of current to be supplied to a motor for moving a shaft of the machine tool when the tool cuts the workpiece. The present invention further comprises a correction unit that corrects the amount of accumulated chips estimated by the estimation unit, based on a machining mode specifying a shape of a chip generated when the tool cuts the workpiece. Advantageous effects of the invention

[0009] The advantageous effect of a numerical control device according to the present invention is that it assists the operator in disposing of the chips at the appropriate time. Short description of the characters Fig. 1 is a diagram illustrating a configuration of a numerical control device according to an embodiment. Fig. 2 shows a diagram of a schematic side view of a machine tool according to the embodiment. Fig. 3 shows a table for explaining a processing mode according to the embodiment. Description of embodiments

[0010] A numerical control device according to an embodiment of the present invention will be described in detail below with reference to the drawings. It should be noted that the present invention is not limited to the embodiment. Embodiment

[0011] The representation of Fig. Figure 1 shows a configuration of a numerical control device 1 according to the embodiment. The numerical control device 1 is a device that controls a machine tool 2. Fig. 1 also shows the machine tool 2. In the embodiment, the numerical control device 1 controls the machine tool 2 when a machining tool mounted on the machine tool 2 is machining a workpiece to be machined, and estimates the amount of accumulated chips generated when the tool is machining the workpiece. The tool and the workpiece are in Fig. 1. The tool and the workpiece will be described later with reference to Fig. 2 described.

[0012] Before describing a configuration of the numerical control device 1, a configuration of the machine tool 2 will first be described. The machine tool 2 comprises a tool holder on which the tool is mounted, as well as an X-shaft 21, a Y-shaft 22, and a Z-shaft 23 for moving the tool holder. The X-shaft 21, the Y-shaft 22, and the Z-shaft 23 do not define directions, but represent components of the machine tool 2. The X-shaft 21, Y-shaft 22, and Z-shaft 23 are each perpendicular to the other two shafts. The tool holder is in Fig. 1 is not shown. The tool holder will be described later with reference to Fig. 2 described.

[0013] The machine tool 2 further has a main shaft 24 on which a workpiece is mounted. The main shaft 24 does not serve to define the direction, but is a component of the machine tool 2. The main shaft 24 is rotatable. The machine tool 2 further has an X-shaft motor 25 for driving the X-shaft 21, a Y-shaft motor 26 for driving the Y-shaft 22, a Z-shaft motor 27 for driving the Z-shaft 23, and a main shaft motor 28 for driving the main shaft 24.

[0014] The machine tool 2 further includes an X-shaft amplifier 29 for supplying power to the X-shaft motor 25, a Y-shaft amplifier 30 for supplying power to the Y-shaft motor 26, a Z-shaft amplifier 31 for supplying power to the Z-shaft motor 27, and a main shaft amplifier 32 for supplying power to the main shaft motor 28. The X-shaft motor 25 is operated based on the power supplied by the X-shaft amplifier 29, the Y-shaft motor 26 is operated based on the power supplied by the Y-shaft amplifier 30, the Z-shaft motor 27 is operated based on the power supplied by the Z-shaft amplifier 31, and the main shaft motor 28 is operated based on the power supplied by the main shaft amplifier 32.

[0015] The configuration of the numerical control device 1 is described below. The numerical control device 1 includes a receiving unit 11 for receiving, from outside the numerical control device 1, first information indicating a machining state when the tool mounted on the machine tool 2 is cutting a workpiece, and second information indicating a machining mode indicating the shape of the chips when the tool is cutting a workpiece.The machining condition specifies, for example, the shape of a workpiece and / or the material of the workpiece and / or the shape of a tool and / or the material of the tool and / or the cutting depth with which the tool is to machine the workpiece and / or the feed rate of the tool and / or the respective travel distance for the X-shaft 21, Y-shaft 22 and Z-shaft 23 of the machine tool 2 and / or the respective travel speed of the X-shaft 21, the Y-shaft 22 and the Z-shaft 23 and / or the number of revolutions per unit time of the main shaft 24 of the machine tool 2. The machining mode will be described later using . Fig. 3 described.

[0016] The numerical control device 1 further includes a storage unit 12 for storing the first information and second information received by the receiving unit 11. A flash memory can be exemplified as the storage unit 12. The numerical control device 1 further includes an instruction unit 13 for calculating an instruction value for controlling the respective operations of the X-shaft 21, the Y-shaft 22, the Z-shaft 23, and the main shaft 24 of the machine tool 2 based on the machining state indicated by the first information stored in the storage unit 12 and the machining mode indicated by the second information stored in the storage unit 12.

[0017] The numerical control device 1 further includes a communication unit 14 for transmitting information indicating the instruction value calculated by the instruction unit 13 to the X-wave amplifier 29, the Y-wave amplifier 30, the Z-wave amplifier 31, and the main wave amplifier 32. Specifically, the communication unit 14 transmits to the X-wave amplifier 29 information indicating an X-wave instruction value calculated by the instruction unit 13 for controlling the operation of the X-wave 21, and to the Y-wave amplifier 30 information indicating a Y-wave instruction value calculated by the instruction unit 13 for controlling the operation of the Y-wave 22.The communication unit 14 transmits to the Z-wave amplifier 31 information indicating a Z-wave instruction value calculated by the instruction unit 13 for controlling the operation of the Z-wave 23, and to the main wave amplifier 32 information indicating a main wave instruction value calculated by the instruction unit 13 for controlling the operation of the main wave 24.

[0018] The X-wave amplifier 29 receives information indicating the X-wave command value from the communication unit 14 and feeds a current corresponding to the X-wave command value to the X-wave motor 25. The Y-wave amplifier 30 receives information indicating the Y-wave command value from the communication unit 14 and feeds a current corresponding to the Y-wave command value to the Y-wave motor 26. The Z-wave amplifier 31 receives information indicating the Z-wave command value from the communication unit 14 and feeds a current corresponding to the Z-wave command value to the Z-wave motor 27. The main wave amplifier 32 receives information indicating the main wave command value from the communication unit 14 and feeds a current corresponding to the main wave command value to the main wave motor 28.

[0019] The X-shaft motor 25 transmits the power based on the current supplied from the X-shaft amplifier 29 to the X-shaft 21 via a transmission mechanism for driving the X-shaft 21. The transmission mechanism is in Fig. 1 not shown. A ball screw is an example of the transmission mechanism. Similarly, the Y-shaft motor 26 transmits the power based on the current input from the Y-shaft amplifier 30 to the Y-shaft 22 via a transmission mechanism for driving the Y-shaft 22. The Z-shaft motor 27 transmits the power based on the current input from the Z-shaft amplifier 31 to the Z-shaft 23 via a transmission mechanism for driving the Z-shaft 23. The main shaft motor 28 transmits the power based on the current input from the main shaft amplifier 32 to the main shaft 24 to drive the Z-shaft 24. Thus, the X-shaft motor 25 causes the X-shaft 21 to move, the Y-shaft motor 26 causes the Y-shaft 22 to move, the Z-shaft motor 27 causes the Z-shaft 23 to move, and the main shaft motor 28 causes the main shaft 24 to move.

[0020] Thus, the numerical control device 1 controls the machine tool 2 depending on the machining condition and machining mode. The machine tool 2 moves the tool and the workpiece according to the control provided by the numerical control device 1. The tool mounted on the machine tool 2 performs machining of the workpiece according to the machining condition and machining mode.

[0021] The X-wave amplifier 29 transmits X-wave current information indicating the value of the current fed to the X-wave motor 25 to the communication unit 14, and the Y-wave amplifier 30 transmits Y-wave current information indicating the value of the current fed to the Y-wave motor 26 to the communication unit 14. The Z-wave amplifier 31 transmits Z-wave current information indicating the value of the current fed to the Z-wave motor 27 to the communication unit 14, and the main-wave amplifier 32 transmits main-wave current information indicating the value of the current fed to the main-wave motor 28 to the communication unit 14.

[0022] The numerical control device 1 further includes an estimation unit 15 for estimating the amount of chip accumulation generated during machining of the workpiece based on the machining condition indicated by the first information stored in the storage unit 12 and the respective current values ​​indicated by the X-shaft current information, the Y-shaft current information, the Z-shaft current information, and the main shaft current information. In other words, the estimation unit 15 estimates the amount of chip accumulation generated during machining of the workpiece by the tool based on the machining conditions and the current values ​​to be supplied to the motors for driving the shafts of the machine tool 2 when the tool is machining the workpiece. At least one of the shafts is the main shaft 24.The shafts may include the main shaft 24 and / or the X-shaft 21 and / or the Y-shaft 22 and / or the Z-shaft 23. At least one of the motors is the main shaft motor 28. The motors may include the main shaft motor 28 and / or the X-shaft motor 25 and / or the Y-shaft motor 26 and / or the Z-shaft motor 27.

[0023] Specifically, the communication unit 14 receives the X-wave current information from the X-wave amplifier 29, the Y-wave current information from the Y-wave amplifier 30, the Z-wave current information from the Z-wave amplifier 31, and the main-wave current information from the main-wave amplifier 32, and transmits the X-wave current information, the Y-wave current information, the Z-wave current information, and the main-wave current information to the estimation unit 15. The estimation unit 15 receives the X-wave current information, the Y-wave current information, the Z-wave current information, and the main-wave current information from the communication unit 14. The estimation unit 15 estimates the amount of accumulating chips based on the machining conditions and the values ​​of the currents indicated by the X-wave current information, Y-wave current information, Z-wave current information, and main-wave current information received by the communication unit 14.

[0024] When machining a workpiece, a machining-dependent load is applied to the main shaft 24, and the main shaft motor 28 is therefore required to generate a relatively large power, causing the current value indicated by the main shaft current information to be relatively large. In other words, the current value indicated by the main shaft current information when machining a workpiece is larger than the current value indicated by the main shaft current information when machining a workpiece. Hereinafter, the machining-dependent load is referred to as the "cutting load."

[0025] It is assumed that the current value indicated by the main shaft current information when machining a workpiece is a first value, and the current value indicated by the main shaft current information when not machining a workpiece is a second value. As described above, the current value indicated by the main shaft current information when machining a workpiece is larger than the current value indicated by the main shaft current information when not machining a workpiece. Thus, the first value is larger than the second value.

[0026] Thus, whether machining of a workpiece is occurring can be determined by determining whether the current value indicated by the main shaft current information is the first value or the second value. Furthermore, whether chips are being generated can be determined by determining whether the current value indicated by the main shaft current information is the first value or the second value. Therefore, the amount of chips accumulating is correlated with the period of time during which the current value indicated by the main shaft current information corresponds to the first value. In other words, the current value indicated by the main shaft current information and the amount of chips accumulating are correlated with each other.As previously described, the values ​​of the currents that must be fed into the motors to move the shafts of the machine tool 2 when machining a workpiece with the tool and the amount of chips that accumulate are correlated with each other.

[0027] The machining condition, for example, specifies the material of the workpiece. The amount of chip accumulation depends on the material of the workpiece. The machining condition, for example, specifies the cutting depth at which the tool should cut the workpiece. The amount of chip accumulation is relatively large when the cutting depth is relatively large, and the amount of chip accumulation is relatively small when the cutting depth is relatively small. In this way, the machining condition and the amount of chip accumulation are correlated.

[0028] As described above, the current values ​​that must be fed to the motors to move the shafts of the machine tool 2 when machining a workpiece with the tool, the amount of chip accumulation, and the machining state and the amount of chip accumulation are correlated with each other. The estimation unit 15 estimates the amount of chip accumulation generated when the tool is machining the workpiece based on the machining condition and the current values ​​that must be fed to the motors to move the shafts of the machine tool 2 when machining the workpiece with the tool. As described above, at least one of the shafts forms the main shaft 24. The shafts may include the main shaft 24 and / or the X-shaft 21 and / or the Y-shaft 22 and / or the Z-shaft 23. At least one of the motors is the main shaft motor 28.The motors may include the main shaft motor 28 and / or the X-shaft motor 25 and / or the Y-shaft motor 26 and / or the Z-shaft motor 27.

[0029] The numerical control device 1 further includes a correction unit 16 for correcting the amount of accumulating chips estimated by the estimation unit 15 based on the machining mode indicated by the second information stored in the storage unit 12. As described above, the machining mode specifies the shape of the chips generated when the tool cuts the workpiece. Details of the functions of the correction unit 16 will be explained later using examples of the machining mode with reference to Fig. 3 described.

[0030] The numerical control device 1 further includes a determination unit 17 for determining whether the amount of accumulated chips resulting from the correction by the correction unit 16 is greater than or equal to a predetermined amount. The determination unit 17 has a storage unit. An example of the storage unit is a flash memory. Information about the predetermined amount is stored in advance in the storage unit. The determination unit 17 determines, based on the information stored in the storage unit, whether the amount of accumulated chips resulting from the correction by the correction unit 16 is greater than or equal to the predetermined amount.

[0031] The numerical control device 1 further includes an information unit 18 for providing information to the outside of the numerical control device 1 indicating that the amount of accumulated chips resulting from the correction by the correction unit 16 is equal to or greater than the predetermined amount. If the determination unit 17 determines that the amount of accumulated chips resulting from the correction by the correction unit 16 is equal to or greater than a predetermined amount, the information unit 18 provides information indicating that the amount of accumulated chips is equal to or greater than the predetermined amount.

[0032] The information unit 18 provides the information indicating that the amount of accumulated chips resulting from the correction by the correction unit 16 is equal to or greater than the predetermined amount, for example, using sound or light. Alternatively, the information unit 18 may include a loudspeaker or a lamp and provide the information indicating that the amount of accumulated chips resulting from the correction by the correction unit 16 is equal to or greater than the predetermined amount using the loudspeaker or the lamp.

[0033] Next, the machine tool 2, a tool T and a workpiece W are described. The schematic representation of Fig. Figure 2 illustrates a side view of the machine tool 2 according to the embodiment. As described above, the machine tool 2 includes the X-shaft 21, the Y-shaft 22, the Z-shaft 23, the main shaft 24, the X-shaft motor 25, the Y-shaft motor 26, the Z-shaft motor 27, the main shaft motor 28, the X-shaft amplifier 29, the Y-shaft amplifier 30, the Z-shaft amplifier 31, and the main shaft amplifier 32. Fig. 2, the direction parallel to the X-shaft 21 is designated “X” and the direction parallel to the Z-shaft 23 is designated “Z”.

[0034] The machine tool 2 further comprises a tool holder 33 on which the tool T is mounted, and a transmission mechanism 34 for moving the tool holder 33. Specifically, the transmission mechanism 34 transmits the power from the X-shaft motor 25 to the X-shaft 21 to move the tool holder 33 in a direction parallel to the X-shaft 21. Although this is Fig. 2 is not shown, the machine tool 2 further comprises a transmission mechanism for moving the tool holder 33 in a direction parallel to the Y-shaft 22 and a transmission mechanism for moving the tool holder 33 in a direction parallel to the Z-shaft 23. In Fig. 2 also shows the main shaft 24. The main shaft 24 rotates in the direction of an arrow A about a rotation axis C. The rotation axis C encompasses the central axis of the main shaft 24. Fig. 2 illustrates a state where the workpiece W is mounted on the main shaft 24. Fig. 2 further illustrates a state in which the tool T is mounted on the tool holder 33. The tool T is a cutting tool for machining the workpiece W.

[0035] The machine tool 2 is operated under the control of the numerical control device 1, wherein the main shaft 24 on which the workpiece W is mounted rotates in the direction of the arc arrow A about the rotation axis C, and the tool T comes into contact with the workpiece W rotating with the rotation of the main shaft 24, whereby the tool T cuts the workpiece W.

[0036] Next, the editing mode is described. Fig. 3 is a table for explaining the machining mode according to the embodiment. In the embodiment, a first machining mode and a second machining mode are defined. The first machining mode is a mode in which the workpiece W is formed of a circular bar, and the tool T machines the workpiece W mounted on the main shaft 24 with the center axis of the circular bar coinciding with the center axis of the main shaft 24. The second machining mode is a mode in which the workpiece W is a bar other than a circular bar, the bar having an elliptical cross-section perpendicular to its center axis, and the tool T machines the workpiece W mounted on the main shaft 24 with the center axis of the bar coinciding with the center axis of the main shaft 24.

[0037] In other words, the machining is carried out in the first machining mode when the workpiece W is a circular bar, or in the second machining mode when the workpiece W is a bar that is different from a circular bar and has an elliptical cross-section perpendicular to its central axis. Fig. 3 specifies the motor rotation directions, the current purposes, and the chip shapes for both machining in the first machining mode and machining in the second machining mode. Thus, for both the first machining mode and the second machining mode, the relationship between the motor rotation directions and the chip shapes, the relationship between the purposes of the currents flowing in the motors and the chip shapes, and the relationship between the motor rotation directions and the purposes of the currents flowing in the motors and the chip shapes are specified.

[0038] Since in Fig. 2 When the tool T rotates the workpiece W in the X direction and then in the Z direction, both the direction of rotation of the X-shaft motor 25 assigned to the X-shaft 21 and the direction of rotation of the Z-shaft motor 27 assigned to the Z-shaft 23 are unidirectional during machining in the first machining mode. The direction of rotation of the main shaft motor 28 assigned to the main shaft 24 is also unidirectional. Since the directions of rotation of the X-shaft motor 25, the Z-shaft motor 27, and the main shaft motor 28 are unidirectional, neither an acceleration torque nor a braking torque needs to be generated.

[0039] Thus, the currents flowing in the X-shaft motor 25, the Z-shaft motor 27, and the main shaft motor 28 are currents resulting from the cutting load. In other words, during machining in the first machining mode, the currents flowing in the X-shaft motor 25, the Z-shaft motor 27, and the main shaft motor 28 are used for the cutting load. During machining in the first machining mode, the shape of the chips generated when the tool T cuts the workpiece W is spiral because the tool T is constantly in contact with the workpiece W. This means that the chips are long.

[0040] During machining in the second machining mode, since the cross section of the workpiece W is elliptical, the tool T must reciprocate in the radial direction of the workpiece W synchronously with the rotation of the workpiece W while the workpiece W is rotated. Specifically, the tool T must reciprocate twice in the radial direction of the workpiece W during one revolution of the workpiece W. In other words, the tool holder 33 must move back and forth twice in the direction parallel to the X-shaft 21 during one revolution of the workpiece W. In addition, the X-shaft 21 must move back and forth twice. Therefore, during machining in the second machining mode, the rotation direction of the X-shaft motor 25 assigned to the X-shaft 21 is bidirectional. The rotation direction of the Z-shaft motor 27 assigned to the Z-shaft 23 and the rotation direction of the main shaft motor 28 assigned to the main shaft 24 are unidirectional.

[0041] Since the rotation direction of the X-shaft motor 25 associated with the X-shaft 21 is bidirectional during machining in the second machining mode, the inertia of the transmission mechanism 34 increases, requiring acceleration and deceleration torques to be generated. Therefore, a current generating acceleration and deceleration torque must be supplied to the X-shaft motor 25, and the magnitude of the current must be periodically changed. Therefore, during machining in the second machining mode, the current flowing into the X-shaft motor 25 is used for the cutting load and acceleration / deceleration, and the currents flowing into the Z-shaft motor 27 and the main shaft motor 28 are used for the cutting load. During machining in the second machining mode, the shape of the chips generated when the workpiece W is machined by the tool T is short chips because the tool T periodically moves away from the workpiece W.This causes the chips to be divided into a multitude of short chips.

[0042] Since the tool T moves back and forth during machining in the second machining mode as described above, Fig. 3 the term “vibration turning” is entered in a field explaining the second processing mode. In a field explaining the first processing mode of Fig. 3, the term “normal turning” was written in comparison to “vibration turning”.

[0043] In the embodiment, the correction unit 16 determines whether the machining mode indicated by the second information stored in the storage unit 12 is the first machining mode or the second machining mode. Based on the determined machining mode, the correction unit 16 determines whether the chips are long or split into short chips, and corrects the amount of accumulated chips estimated by the estimation unit 15 based on the determination result.

[0044] As stated above, the numerical control device 1 according to the embodiment estimates the amount of chips generated when the workpiece W is machined by the tool T based on the machining condition and the current values ​​to be supplied to the motors of the machine tool 2 when the workpiece W is machined by the tool T, and corrects the estimated amount of chips accumulated based on the machining mode. Specifically, the numerical control device 1 determines whether the chips are long or short based on the machining mode and corrects the amount of chips accumulated based on the determination result.

[0045] Even with the same chip mass, the volume of long chips tends to be larger than the volume of short chips because gaps often occur between long chips. As described above, the numerical control device 1 determines whether the chips are long or divided into short chips based on the machining mode and corrects the amount of accumulating chips based on the determination, thereby enabling a more accurate estimation of the amount of accumulating chips. This enables the numerical control device 1 to inform an operator of an appropriate timing for disposing of the chips. Therefore, the advantageous effect achieved by the numerical control device 1 is to assist an operator in disposing of the chips at an appropriate timing.

[0046] It should be noted that, in the above-described embodiment, the communication unit 14 transmits to the X-wave amplifier 29 information indicating the X-wave instruction value for controlling the operation of the X-wave 21, to the Y-wave amplifier 30 information indicating the Y-wave instruction value for controlling the operation of the Y-wave 22, to the Z-wave amplifier 31 information indicating the Z-wave instruction value for controlling the operation of the Z-wave 23, and to the main-wave amplifier 32 information indicating the main-wave instruction value for controlling the operation of the main-wave 24. However, the communication unit 14 may transmit the information indicating the X-wave instruction value, the information indicating the Y-wave instruction value, the information indicating the Z-wave instruction value, and the information indicating the main-wave instruction value to any of the amplifiers, i.e.the X-wave amplifier 29, the Y-wave amplifier 30, the Z-wave amplifier 31, or the main wave amplifier 32. In this case, the information indicating the X-wave instruction value, the information indicating the Y-wave instruction value, the information indicating the Z-wave instruction value, and the information indicating the main wave instruction value are transmitted and received between the X-wave amplifier 29, the Y-wave amplifier 30, the Z-wave amplifier 31, and the main wave amplifier 32.

[0047] Also, the X-wave current information, the Y-wave current information, the Z-wave current information, and the main wave current information can be transmitted and received in the same way between the X-wave amplifier 29, the Y-wave amplifier 30, the Z-wave amplifier 31, and the main wave amplifier 32, so that the X-wave current information, the Y-wave current information, the Z-wave current information, and the main wave current information are acquired in any of the amplifiers, i.e., the X-wave amplifier 29, the Y-wave amplifier 30, the Z-wave amplifier 31, or the main wave amplifier 32. In this case, the communication unit 14 receives the X-wave current information, the Y-wave current information, the Z-wave current information, and the main wave current information from the X-wave amplifier 29, the Y-wave amplifier 30, the Z-wave amplifier 31, or the main wave amplifier 32.

[0048] In Fig.3, the first machining mode and the second machining mode each specify a first relationship between the rotation directions of the motors and the shape of the chips, a second relationship between the purposes of the currents flowing in the motors and the shape of the chips, and a third relationship between the rotation directions of the motors and the purposes of the currents flowing in the motors and the shape of the chips. However, the machining modes may specify any of the above-described first relationship, second relationship, or third relationship.

[0049] In the above-described embodiment, the information about the predetermined amount is stored in advance in the storage unit of the determination unit 17, and the determination unit 17 determines whether the amount of accumulated chips resulting from the correction by the correction unit 16 is greater than or equal to the predetermined amount. Alternatively, the receiving unit 11 may receive information indicating the amount specified from outside the numerical control device 1, and the information indicating the predetermined amount received by the receiving unit 11 may be stored in the storage unit of the determination unit 17. In this case, the operator can freely specify the predetermined amount and thus change the timing for disposing of the chips.

[0050] The receiving unit 11 can receive chip accumulation correction information from outside the numerical control device 1. Once the receiving unit 11 has received the chip accumulation correction information, the correction unit 16 corrects the chip accumulation amount based on the machining mode and the information received from the receiving unit 11. In this case, the operator can cause the numerical control device 1 to make a more accurate chip accumulation estimate by checking the actual machining and inputting chip accumulation correction information to the numerical control device 1. In other words, the numerical control device 1 is able to more accurately estimate the chip accumulation amount based on the chip accumulation correction information.

[0051] The numerical control device 1 may have a function that stops the operation of the machine tool 2 when the determination unit 17 determines that the amount of accumulating chips resulting from the correction by the correction unit 16 is greater than or equal to the predetermined amount.

[0052] The configurations presented in the above-described embodiment are examples of the present invention, and may be combined with other known technologies, or may be partially omitted or changed without departing from the scope of the present invention. List of reference symbols 1 numerical control device; 2 machine tools; 11 receiving unit; 12 storage unit; 13 instruction unit; 14 communication unit; 15 estimation unit; 16 correction unit; 17 Unit of determination; 18 information unit; 21 X-wave; 22 Y-wave; 23 Z-wave; 24 main shaft; 25 X-shaft motor; 26 Y-shaft motor; 27 Z-shaft motor; 28 main shaft motor; 29 X-wave amplifiers; 30 Y-wave amplifiers; 31 Z-wave amplifiers; 32 main wave amplifiers; 33 tool holders; 34 transmission mechanism; A bow arrow; C rotation axis; T tool; W workpiece.

Claims

[1] Numerical control device comprising: an estimation unit for estimating an amount of accumulated chips generated when a tool mounted on a machine tool machines a workpiece, based on a machining condition for machining the workpiece with the tool and a value of a current to be supplied to a motor for moving a shaft of the machine tool when the workpiece is machined with the tool; and a correction unit for correcting the amount of accumulating chips estimated by the estimation unit based on a machining mode that specifies a shape of the chips generated when the tool cuts the workpiece. [2] A numerical control device according to claim 1, wherein the machining condition indicates a material of the workpiece and / or a cutting depth and / or a feed rate of the tool. [3] The numerical control device according to claim 1 or 2, wherein the machining mode sets a relationship between a rotation direction of the motor and the shape of the chips, a relationship between a purpose of the current flowing into the motor and the shape of the chips, or a relationship between the rotation direction of the motor and the purpose of the current flowing into the motor and the shape of the chips, and the correction unit determines whether the chips are long or divided into a plurality of short chips based on the machining mode, and corrects the amount of accumulating chips based on a determination result. [4] A numerical control device according to any one of claims 1 to 3, further comprising: a receiving unit for receiving information for correcting the amount of accumulating chips, wherein the correction unit corrects the amount of accumulating chips based on the machining mode and the information received from the receiving unit.

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