Machining condition correction assistance device for NC machine tool

Abstract

This device (10) for assisting correction of a machining condition in an NC machine tool (30) comprises: a data processing unit (22) that calculates at least one piece of data of load information during machining of a workpiece (W); a storage unit (20) that stores the data calculated by the data processing unit for each process; a process list creation unit (12) that creates, on the basis of the data stored in the storage unit, a process list including the at least one piece of data of load information for each process; a tool trajectory image generation unit (14) that generates an image of a tool trajectory in which the data of the storage unit is superimposed on tool trajectory data of every moment; and an engagement unit (16) that causes the process list and the tool trajectory image to be displayed on a display unit in an engaged manner.

Description

NC machine tool processing condition correction support device

[0001] The present invention relates to a machining condition correction support device that inputs a machining program and machining conditions into an NC device and supports the correction of machining conditions in an NC machine tool that machines a workpiece by sequentially changing tools.

[0002] When machining workpieces with machine tools, if the machining conditions are not appropriate, chatter vibrations and overloads can have a negative impact on workpiece quality and tool life. In a typical production process, trial and error is performed on machining conditions when machining the first product to find the appropriate conditions, and these machining conditions are then applied to mass production. This process of setting machining conditions requires a lot of man-hours, and searching for better conditions requires the experience and skill of the operator. For this reason, in today's world where labor turnover is an issue, there is a demand for unskilled operators to be able to set machining conditions quickly and easily.

[0003] Conventionally, machining condition correction support functions have suggested appropriate spindle rotation speeds based on vibration data from actual machining to suppress chatter vibration. However, when setting machining conditions for NC machine tools with automatic tool changers, such as machining centers, it is necessary to correct the conditions for multiple tools, which takes time. Furthermore, chatter vibration can reduce the quality of the machined surface of a workpiece and result in quality defects. However, when chatter vibration occurs only on a portion of the machined surface of a workpiece, operators may overlook the presence of chatter on large workpieces. Furthermore, even when chatter vibration is discovered, it takes time to identify which tool and which machining conditions are causing the problem.

[0004] To solve this problem, for example, Patent Document 1 describes a vibration information display device that instantly displays chatter vibration information on a monitor, thereby quickly notifying an operator who has left the machine of a machining abnormality.

[0005] Japanese Patent Application Laid-Open No. 2016-224695

[0006] The vibration information display device described in Patent Document 1 can notify the operator that a machining abnormality has occurred, but it cannot tell the operator which process is causing the abnormality or which machining part is causing the abnormality, so it is not possible to easily correct the machining conditions to eliminate the abnormality.

[0007] The present invention has as its technical object to solve the problems of the prior art, and aims to provide a machining condition correction support device for NC machine tools that enables even an unskilled person to easily search for appropriate machining conditions for each process in a short amount of time.

[0008] In order to achieve the above-mentioned object, according to the present invention, there is provided an apparatus for supporting the correction of machining conditions in an NC machine tool which inputs a machining program and machining conditions into an NC device and machines a workpiece by sequentially changing tools, the apparatus comprising: a data processing unit which calculates at least one piece of data of load information during workpiece machining; a memory unit which stores data calculated by the data processing unit for each process during workpiece machining; a process list creation unit which creates a process list including at least one piece of data of load information for each process based on the data stored in the memory unit during or after workpiece machining; a tool path image generation unit which generates, during or after workpiece machining, an image of a tool path in which data from the memory unit is superimposed on tool path data at each moment; and a linking unit which links the process list and the tool path image and displays them on a display unit.

[0009] The process list and the tool path image are displayed in conjunction with each other on the display unit, so the operator can compare the process list and the tool path image, making it possible for even an unskilled operator to easily correct the machining conditions.

[0010] FIG. 1 is a schematic block diagram showing a preferred embodiment of a machining condition modification support device shown together with an NC machine tool. FIG. 2 is a schematic diagram of a machining condition modification window displaying a process list and a tool path image. FIG. 3 is a schematic diagram showing an example of a process list. FIG. 4 is a schematic diagram of an example of a tool path image. FIG. 5 is a flowchart showing processing in a data processing unit and a storage unit for acquiring load information and machining conditions. FIG. 6 is a flowchart showing an example of a method for modifying machining conditions based on load information obtained in actual machining of a workpiece. FIG. 7 is a flowchart showing an example of a method for modifying machining conditions based on load information obtained in simulated machining of a workpiece using a simulator. FIG. 8 is a flowchart showing an example of a method for identifying a machining portion causing a problem from a tool path image, and checking the tool, load information, and machining conditions (feed rate and spindle rotation speed) that will machine the machining portion from the process list. FIG. 9 is a flowchart showing an example of a method for identifying a machining portion causing a problem from the process list, and checking the tool, load information, and machining conditions (feed rate and spindle rotation speed) that will machine the machining portion.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will now be described with reference to the accompanying drawings. Referring to FIG. 1, an example of a machining condition modification support device 10 and an NC machine tool 30 are shown.

[0012] The NC machine tool 30 shown as an example comprises a bed 32 as a base fixed to the floor of a factory, a column 34 mounted on the rear end (right side in Figure 1) of bed 32 so as to be able to reciprocate on the upper surface of bed 32 in the left-right direction or in the X-axis direction (a direction perpendicular to the plane of the paper in Figure 1), a Y-slider 36 mounted on the front of column 34 so as to be able to move up and down or in the Y-axis direction, a spindle head 38 mounted on Y-slider 36, and a table 42 mounted on the upper surface of the front part (left side in Figure 1) of bed 32 so as to be able to move back and forth in the front-to-back direction or in the Z-axis direction (left and right direction in Figure 1).

[0013] A workpiece W is fixed to the upper surface of the table 42. In the example shown in FIG. 1, the workpiece W is fixed to the table 42 via a workpiece fixture 42a such as a tombstone. The NC machine tool 30 also includes an operation panel (not shown) that allows an operator to operate the NC machine tool 30. The spindle 40 is supported by the spindle head 38 so as to be rotatable about a horizontal rotation axis O extending in the Z-axis direction. The spindle head 38 includes a spindle motor 50 that rotationally drives the spindle 40. The spindle motor 50 is preferably formed by a built-in motor disposed within a housing (not shown) of the spindle head 38.

[0014] A rotary encoder 62 that measures the rotational speed of the spindle 40 is attached to the rear end of the spindle 40. A tool T that machines a workpiece W fixed to a table 42 is attached to the tip of the spindle 40. The spindle 40 is equipped with a displacement sensor (not shown) for measuring cutting force. An acceleration sensor 54 that measures vibrations generated in the spindle 40 is attached to the spindle head 38.

[0015] The operation panel includes a display panel that displays various operating conditions and machining conditions of the NC machine tool 30. The display panel can be formed as a touch panel that allows an operator to select an area touched or input corresponding to the area touched by touching the screen with a finger or a touch pen. The operation panel can also include a key input unit. By operating the key input unit, predetermined numbers and characters can be input into the NC device 52.

[0016] NC machine tool 30 may further include peripheral devices such as a tool magazine (not shown) that stores multiple tools used in machining, an automatic tool changer (not shown) that changes tools between the tool magazine and spindle 40, and a coolant supply device (not shown) that supplies coolant to the machining area of ​​NC machine tool 30, as well as a machine control device (not shown) that controls the peripheral devices. In this embodiment, NC machine tool 30 constitutes a horizontal machining center, but NC machine tool 30 may also be a vertical machining center that rotates the spindle about a vertical rotation axis. It may also be another NC machine tool that performs turning, grinding, etc.

[0017] The column 34 is provided so as to be able to reciprocate along a pair of X-axis guide rails (not shown) extending in the X-axis direction on the upper front surface of the table 42. The bed 32 is provided with an X-axis feed device that drives the column 34 reciprocally along the X-axis guide rails. The X-axis feed device includes a ball screw (not shown) extending in the X-axis direction and an X-axis motor 44 connected to one end of the ball screw, and a nut (not shown) that engages with the ball screw is attached to the column 34. An X-scale 56 that measures the coordinate position of the column 34 in the X-axis direction is also attached to the bed 32.

[0018] Y slider 36 is provided so as to be able to reciprocate along a pair of Y-axis guide rails extending in the Y-axis direction on the front surface of column 34. Column 34 is provided with a ball screw (not shown) extending in the Y-axis direction and a Y-axis motor 46 connected to one end of the ball screw as a Y-axis feed device that drives Y slider 36 reciprocally along the Y-axis guide rails, and a nut (not shown) that engages with the ball screw is attached to Y slider 36. Column 34 is also provided with a Y scale 58 that measures the coordinate position of Y slider 36 in the Y-axis direction.

[0019] The table 42 is provided so as to be able to reciprocate along a pair of Z-axis guide rails (not shown) that extend in the horizontal Z-axis direction (left and right direction in FIG. 1) on the upper surface of the bed 32, and the bed 32 is provided with a Z-axis feed device that drives the table 42 reciprocally along the Z-axis guide rails, which includes a ball screw (not shown) that extends in the Z-axis direction and a Z-axis motor 48 connected to one end of the ball screw, and a nut (not shown) that engages with the ball screw is attached to the table 42. A Z scale 60 that measures the coordinate position of the table 42 in the Z-axis direction is also attached to the bed 32.

[0020] X-axis motor 44, Y-axis motor 46, Z-axis motor 48, X-scale 56, Y-scale 58, Z-scale 60, spindle motor 50, and rotary encoder 62 are connected to NC device 52, and X-axis motor 44, Y-axis motor 46, Z-axis motor 48, and spindle motor 50 are controlled in accordance with a machining program input to NC device 52, based on measurements of X-scale 56, Y-scale 58, Z-scale 60, and rotary encoder 62. In this way, NC machine tool 30 rotates spindle 40 in accordance with the machining program supplied to NC device 52, while moving tool T at the tip of spindle 40 relative to workpiece W on table 42, thereby machining workpiece W.

[0021] The machining condition modification support device 10 comprises, as main components, a process list creation unit 12, a tool path image generation unit 14, a linking unit 16, a machining condition modification unit 18, a memory unit 20, a data processing unit 22, a display unit 24, and a machining condition input unit 26. The process list creation unit 12, the tool path image generation unit 14, the linking unit 16, the machining condition modification unit 18, and the memory unit 20 can be configured from a computer and related software including a CPU (central processing unit), a memory device such as a RAM (random access memory) or a ROM (read only memory), a storage device such as a HDD (hard disk drive) or an SSD (solid state drive), an RTC (real-time clock) made up of an integrated circuit equipped with a clock function, input / output ports, and a bidirectional bus interconnecting these. The process list creation unit 12, the tool path image generation unit 14, the linking unit 16, the machining condition correction unit 18 and the memory unit 20 may be configured as software as part of the NC device 52 of the NC machine tool 30 shown in FIG. 1 or a machine control device.

[0022] The display unit 24 can be formed, for example, by a display panel of the operation panel of the NC machine tool 30. The machining condition input unit 26 can be formed, for example, by a touch panel, key input unit, etc. constituting the display panel of the operation panel of the NC machine tool 30. When the machining condition modification support device 10 is configured by a personal computer (not shown) independent of the NC machine tool 30 or a mobile terminal such as a tablet (not shown), the display unit 24 and the machining condition input unit 26 can be formed by the display device and keyboard of the personal computer, or the touch panel of the mobile terminal.

[0023] The data processing unit 22 is connected to the X-axis motor 44, the Y-axis motor 46, the Z-axis motor 48, the spindle motor 50, the acceleration sensor 54, the X-scale 56, the Y-scale 58, the Z-scale 60, the spindle motor 50, and the rotary encoder 62, and processes outputs from the X-axis motor 44, the Y-axis motor 46, the Z-axis motor 48, the spindle motor 50, the acceleration sensor 54, the cutting force measuring displacement sensor (not shown), the X-scale 56, the Y-scale 58, the Z-scale 60, the spindle motor 50, and the rotary encoder 62, and outputs the results as load information to the storage unit 20. The load information can include at least one of the cutting force acting on the tool T, the load (torque) applied to the spindle 40, the vibration value due to machining (the amplitude of vibration including the rotation speed component of the spindle 40), the regenerated chatter vibration value, the workpiece removal rate, and the presence or absence of a machining abnormality.

[0024] The cutting force acting on the tool T can be calculated from the current values ​​supplied to the X-axis motor 44, Y-axis motor 46, and Z-axis motor 48, or from the detection value of a displacement sensor built into the spindle 40. Alternatively, it can be calculated from a displacement sensor built into the spindle 40. The load applied to the spindle 40 can be calculated from the current value supplied to the spindle motor 50. The machining vibration value and regenerative chatter vibration value can be calculated based on the measurements of the acceleration sensor 54. The workpiece removal rate is the machined volume of the workpiece W per unit time and can be calculated as the product of the cutting width, cutting depth, and feed rate of the tool. Furthermore, the data processing unit 22 can determine that abnormal machining has occurred when the spindle load, cutting force, vibration value, and regenerative chatter vibration value exceed predetermined thresholds and output a signal indicating a machining abnormality to the memory unit 20. The thresholds can be set, for example, based on normal machining, depending on the machining program, workpiece, or tool type.

[0025] Furthermore, the data processing unit 22 calculates the feed rate and spindle rotation speed as machining conditions. Based on the measurement values ​​of the X scale 56, Y scale 58, and Z scale 60, the data processing unit 22 calculates the feed rate of the tool T relative to the workpiece W and outputs it to the storage unit 20. Based on the measurement value of the rotary encoder 62, the data processing unit 22 calculates the rotation speed of the spindle 40 and outputs it to the storage unit 20.

[0026] 5, there is shown a flowchart illustrating the processing in the data processing unit 22 and the storage unit 20. The data processing unit 22 first records the start and end points of each process (step S10). As an example, one process can be performed for each tool change. The indicators representing the start and end points of a process can be data representing the progress of machining, such as the time when the tool change was performed, the scan count, the cutting distance, or the line number of the machining program.

[0027] The data processing unit 22 accesses the X-axis motor 44, Y-axis motor 46, Z-axis motor 48, spindle motor 50, acceleration sensor 54, cutting force measurement displacement sensor, X-scale 56, Y-scale 58, Z-scale 60, spindle motor 50, and rotary encoder 62 at predetermined time intervals from the start point to the end point of each process and extracts their outputs as data (step S12). At or after the end of each process, the data processing unit 22 calculates load information and machining conditions (feed rate and spindle rotation speed) and outputs them to the memory unit 20 (step S14). The load information includes maximum values ​​for each process of the cutting force acting on the tool T, the load applied to the spindle 40, machining vibration value, regenerative chatter vibration value, and workpiece removal rate. In addition to maximum values, the load information may also include average values ​​and cumulative values.

[0028] The storage unit 20 stores the load information, feed rate, and spindle rotation speed received from the data processing unit 22 in association with indices indicating the start and end points of a process (for example, the time when a tool change was performed). The load information, feed rate, and spindle rotation speed are stored in the storage unit 20 as time-series data arranged in the order of the processes.

[0029] The operation of the machining condition modification support device 10 for the NC machine tool 30 according to this embodiment will be described below. Referring to Figure 2, there is shown a machining condition modification window 100 displayed on the display unit 24. The machining condition modification window 100 includes a plurality of function buttons 102 to 110, including a machining condition modification button 106. When the operator taps the machining condition modification button 106, the machining condition modification window 100 is displayed. The machining condition modification window 100 includes a process list window 200 and a tool path window 300.

[0030] When the operator taps the machining condition correction button 106 displayed on the display unit 24 and selects the machining performance data or simulation data of the machining program for which the operator wants to correct the machining conditions, the collaboration unit 16 outputs a command to create a process list to the process list creation unit 12 and outputs a command to create a tool path image to the tool path image generation unit 14.

[0031] In response to a process list creation command from the linking unit 16, the process list creation unit 12 accesses the storage unit 20 and acquires the machining program number, tool information, machining conditions, load information, spindle rotation speed, and feed rate in association with indexes indicating the start and end points of the process (for example, the time when a tool change was performed), thereby creating the process list shown as an example in Figures 2 and 3. The process list can be created in real time during machining and stored in the storage unit 20, or can be created from time-series data stored in the storage unit 20.

[0032] 3 , a process list window 200 displays a process list consisting of a table including multiple columns and rows. The process list shown as an example includes a process column 202, a tool column 204, a cutting time column 206, a stable spindle rotation speed column 208, a spindle load column 210, a vibration value column 212, a chatter vibration column 214, a spindle rotation speed column 216, and a feed rate column 218. The process list may include a check box 201 for each row to the left of the process column 202.

[0033] The process list may include columns other than those shown in Figure 2. Furthermore, the process list does not need to include all of the columns 202 to 218 shown in Figures 2 and 3. For example, the process list may not include one or more of the following columns other than the process column 202, spindle load column 210, vibration value column 212, and chatter vibration column 214: the tool column 204, cutting time column 206, stable spindle rotation speed column 208, spindle rotation speed column 216, and feed rate column 218. The tool column 204, cutting time column 206, spindle rotation speed column 216, and feed rate column 218 may include buttons (not shown) for selectively displaying them to the operator, as necessary.

[0034] The field of the process column 202 displays the number of a machining program or the tool number. In the example of Fig. 2, the field 202a of the process column 202 displays the main program number O1001, the field 202b displays the subprogram number O2001 indicating one subprogram, subordinate program or subroutine of the main program number O1001, the field 202c displays the tool number T2001 / 1 assigned to one tool used in the machining program of the subprogram number O2001, the field 202d displays the tool number T2002 / 2 assigned to another tool used in the machining program of the subprogram number O2001, and the field 202e displays the tool number T2003 / 3 assigned to yet another tool used in the machining program of the subprogram number O2001. In field 202f, tool number T2003 / 3 assigned to a tool used in the machining program of subprogram number O2001 is displayed, tool number T2004 / 4 assigned to a further tool used in the machining program of subprogram number O2001 is displayed, field 202g, tool number T2005 / 5 assigned to a further tool used in the machining program of subprogram number O2001 is displayed, field 202h, subprogram number O3001 indicating another subprogram, lower-level program or subroutine included in main program number O1001 is displayed, and field 202i, tool number T3001 / 6 assigned to one tool used in the machining program of subprogram number O3001 is displayed.

[0035] 2 and 3, the process column 202 indicates that the upper process indicated by program number O1001 includes two lower processes corresponding to program numbers O2001 and O3001, the lower process corresponding to program number O2001 includes five further lower processes executed by tools corresponding to tool numbers T2002 / 1, T2002 / 2, T2002 / 3, T2002 / 4, and T2002 / 5, and the process corresponding to program number O3001 includes one further lower process executed by a tool corresponding to tool number T3001 / 6. In other words, in the present invention, the process list is a table that defines a process for each tool or tool change and summarizes machining data for each process.

[0036] The tool column 204 displays the type of tool corresponding to the tool number displayed in the process column 202. In the example of Figures 2 and 3, the main program number or subprogram number is displayed in the process column fields 202a, 202b, and 202h corresponding to the fields 204a, 204b, and 204h in the tool column 204, and therefore the fields 204a, 204b, and 204h in the tool column 204 are blank. Fields 204c, 204e, and 204g of tool column 204 display BEM (ball end mill) as the tool type corresponding to tool numbers T2001 / 1, T2003 / 3, and T2005 / 5 in corresponding fields 202c, 202e, and 202g of process column 202, and fields 204d, 204f, and 204i of tool column 204 display FEM (flat end mill) as the tool type corresponding to tool numbers T2002 / 2, T2004 / 4, and T3001 / 6. Tool column 204 may also display types of tools other than ball end mills and flat end mills, such as drills, face milling cutters, and grinding wheels.

[0037] The cutting time is displayed in the field of the cutting time column 206. In the example of Figures 2 and 3, the total time during which cutting feed commands were issued for the tools corresponding to tool numbers T2001 / 1, T2002 / 2, T2003 / 3, T2004 / 4, T2005 / 5, and T3001 / 6 is displayed as the cutting time, the cutting time of the subprogram O2001 is displayed as the sum of the cutting times of the tools corresponding to tool numbers T2001 / 1, T2002 / 2, T2003 / 3, T2004 / 4, and T2005 / 5 used in the subprogram, the cutting time of the subprogram O3001 is displayed as the cutting time of the tool corresponding to tool number T3001 / 6 used in the subprogram, and the cutting time of the main program O1001 is displayed as the sum of the cutting times of the subprogram O2001 and the subprogram O3001.

[0038] The cutting time may be the time required to execute a main program or a subprogram, or the time that a tool corresponding to a tool number is used for cutting, that is, the time that the tool is actually engaged with the workpiece W, calculated and displayed using the following formula: Tc = Lm / Vf where, Tc: cutting time (min), Lm: machining length (mm), and Vf: feed rate (mm / min).

[0039] In the examples of Figures 2 and 3, the cutting times for the processes using tools corresponding to tool numbers T2001 / 1, T2002 / 2, T2003 / 3, T2004 / 4 and T2005 / 5 are 7 minutes 15 seconds, 7 minutes 45 seconds, 6 minutes 50 seconds, 2 minutes 0 seconds and 2 minutes 10 seconds, respectively, and therefore the cutting time for the machining process corresponding to subprogram O2001 is 26 minutes 00 seconds, and the cutting time for the process using tool corresponding to tool number T3001 / 6 is 2 minutes 30 seconds, and therefore the cutting time for the machining process corresponding to subprogram O3001 is 2 minutes 30 seconds, resulting in a cutting time of 28 minutes 30 seconds for the entire main program O1001.

[0040] The spindle load column 210 displays the maximum value of the load acting on the spindle 40 for each process. The load acting on the spindle 40 is defined by the current value (A) supplied to the spindle motor 50 or the torque (Nm) generated by the spindle motor 50. In the example shown in FIGS. 2 and 3, a warning mark ▲ is displayed indicating that the spindle load has reached 105% (a ratio of the motor rated torque to 100%) in the process using the tool corresponding to tool number T3003 / 3, exceeding a predetermined allowable value. The warning mark ▲ is displayed based on an indicator indicating a machining abnormality in the load information stored in the memory unit 20.

[0041] The vibration value column 212 displays the maximum value of the output from the acceleration sensor 54 attached to the spindle 40 for each process. In the example shown in Figures 2 and 3, in the processes using the tools corresponding to tool numbers T2002 / 2 and T2003 / 3, the vibration values ​​of the spindle 40 are 5.0 G (gravitational acceleration) and 9.0 G, respectively, and a warning mark ▲ is displayed indicating that these values ​​exceed the predetermined allowable values. The warning mark ▲ is displayed based on an indicator indicating a machining abnormality in the load information stored in the memory unit 20.

[0042] The chatter vibration column 214 displays the maximum value of regenerated chatter vibration for each process, calculated based on the output of the acceleration sensor 54 attached to the spindle 40. Note that regenerated chatter vibration (self-excited chatter vibration) refers to vibration components resulting from the bending of the tool T due to the load acting on the tool T during cutting. This does not include forced chatter vibration, which is mechanical vibration caused by the vibration of the NC machine tool 30 itself being amplified by the vibration characteristics of the NC machine tool 30 and resulting in intermittent vibration. In the example shown in Figures 2 and 3, a warning mark (▲) is displayed indicating that the maximum value of regenerated chatter vibration reached 70 in the process using the tool corresponding to tool number T3003 / 3, exceeding the predetermined allowable value. The warning mark (▲) is displayed based on an index indicating a machining abnormality in the load information stored in the memory unit 20. The magnitude of the tool chatter vibration value is a dimensionless value obtained using a unique method, with a larger value indicating greater vibration.

[0043] The spindle rotation speed column 216 displays the rotation speed (rpm) of the spindle 40 for each process. The feed rate column 218 displays the relative speed (mm / min) of the tool T with respect to the workpiece W. The stable spindle rotation speed column 208 displays the stable rotation speed calculated by equation (1) described below.

[0044] In response to a tool path generation command from the linking unit 16, the tool path image generating unit 14 accesses the memory unit 20 and acquires the tool number, load information, spindle rotation speed, feed rate, and machine coordinate information, thereby generating a tool path image shown as an example in FIGS. 2 and 4 in the tool path window 300.

[0045] The tool path window 300 depicts the tool paths corresponding to each tool in the process list displayed in the process list window 200, along with the shape of the machined workpiece W. In Fig. 4, tool path 302 represents the tool path (convex truncated cone shape) corresponding to tool number T2001 / 1, tool path 304 represents the tool path (convex rectangular parallelepiped shape) corresponding to tool number T2002 / 2, tool path 306 represents the tool path (convex quadrangular pyramid shape) corresponding to tool number T2003 / 3, tool path 308 represents the tool path (convex cylindrical shape) corresponding to tool number T2004 / 4, tool path 310 represents the tool path (convex hemispherical shape) corresponding to tool number T2005 / 5, and tool path 312 represents the tool path (concave cylindrical shape) corresponding to tool number T3001 / 6.

[0046] The tool path window 300 further includes a load information selection field 314. The load information selection field 314 of the tool path window 300 shown as an example in Figures 2 and 4 is in the form of a drop-down list. By expanding the drop-down list of the load information selection field 314, it is possible to select one of the load information corresponding to the load information displayed in the first row of the process list, in the example of Figure 3, the spindle load, the spindle vibration value, and the tool chatter vibration value. In this example, the load information selection field 314 is in the form of a drop-down list, but it may also be in another form, for example, a table that displays a list of load information.

[0047] The tool paths 302 to 312 can be displayed in different colors according to the selected load information value. A color bar 316 corresponding to the load information value can also be displayed in the tool path window 300. For example, in the example of FIG. 4 , a spindle vibration value is selected as the load information, and spindle vibration values ​​of 0 to 2.0, 2.0 to 4.0, 4.0 to 6.0, 6.0 to 8.0, and 8.0 to 10.0 can be color-coded as green, yellow, orange, red, and purple, respectively. The corners of the contour path marked with an "x" on the tool path 304 are shown in orange in FIG. 4 , corresponding to a spindle vibration value of 5.0 (maximum output value of the acceleration sensor 54) when machining with a tool corresponding to tool number T2002 / 2. The corners of the contour path marked with an x ​​on tool path 306 correspond to a spindle vibration value of 9.0 (maximum output value of acceleration sensor 54) when machining is performed with a tool corresponding to tool number T2003 / 3, and are shown in purple in Figure 4. The parts of tool paths 302 to 312 other than the x marks have small spindle vibration and are shown in green and yellow. Generally, spindle vibration increases at corners where the tool feed direction changes discontinuously, and these often turn orange, red, or purple.

[0048] Since the process list and tool paths are related by indicators indicating the start and end points of the process (for example, the time when a tool change was performed), as shown in FIG. 2 , by displaying them in a single window (machining condition modification window 100), when the operator taps a check box 201 or row displaying a certain tool number in the process list window 200, the linking unit 16 outputs a highlighting command to the tool path image generating unit 14, which then highlights the corresponding tool path in the tool path window 300. In particular, when the operator taps the check box 201 or row displaying a tool number displaying a warning mark ▲, the linking unit 16 highlights the problematic tool path that exceeds the tolerance in the tool path window 300. The highlighting can be performed by blinking or highlighting the display color, etc. Furthermore, the check box 201 can be used to highlight or hide the tool path.

[0049] Conversely, when the operator taps on a tool path in the tool path window 300 that is colored to correspond to high-value load information, such as tool path 304 or tool path 306 in FIG. 4 , near the X mark, the collaboration unit 16 outputs a highlighting command to the process list creation unit 12 to highlight the row (line) of the corresponding tool number T2001 / 2 or T2001 / 3. Highlighting is achieved by flashing the corresponding row (line), changing the display color, highlighting, displaying a check mark in the check box 201, or hiding rows (line) other than the corresponding row (line). In this way, in this embodiment, the process list creation unit 12 and the tool path image generation unit 14 collaborate with each other via the collaboration unit 16 to display the process list and tool path image in one machining condition modification window 100.

[0050] Next, a method for modifying the machining conditions will be described. Referring to FIG. 6 , first, the NC machine tool 30 actually performs machining of the workpiece W (step S20). During the actual machining, the data processing unit 22 reads output values ​​from the X-axis motor 44, Y-axis motor 46, Z-axis motor 48, spindle motor 50, acceleration sensor 54, X-scale 56, Y-scale 58, Z-scale 60, spindle motor 50, and rotary encoder 62 at predetermined time intervals as machining performance data (step S22). Next, when the operator taps the machining condition modification button 106, a machining condition modification window 100 is displayed on the display unit 24, and a process list and a tool path image are displayed in the machining condition modification window 100 (step S24). The tool path image can be generated by reading the coordinate positions of the tip point of the tool T at each moment using the X-scale 56, Y-scale 58, and Z-scale 60 and sequentially connecting them with broken lines.

[0051] The operator identifies problematic processes by referring to the process list and tool path image in the machining condition correction window 100, particularly the warning mark in the process list and the tool path displayed in the color assigned to high-value measurement information in the tool path image (step S26). At that time, even if the operator has little experience or knowledge, the operator can find problematic processes much more easily than by the conventional method of visually inspecting the machined surface of the workpiece by performing the linked operations of tapping on a tool number displayed with a ▲ warning mark in the process list to highlight the corresponding tool path, or tapping on a tool path displayed in the color assigned to high-value measurement information in the tool path image to highlight the corresponding process in the process list.

[0052] The operator, having identified the problematic process, determines whether or not the machining conditions need to be modified (step S28). If the operator determines that the machining conditions do not need to be modified because no warning mark (▲) is displayed in the process list, or the colors of the tool paths in the tool path image are all colors assigned to measurement information with low values ​​(No in step S28), the flowchart ends.

[0053] If a warning mark (▲) is displayed in the process list, or a tool path in a color assigned to high-value measurement information is displayed in the tool path image, and the operator determines that the machining conditions need to be modified (Yes in step S28), the operator inputs the modified machining conditions from the machining condition input unit 26 in Figure 1 to the NC device 52.

[0054] For example, if the chatter vibration value of the tool is higher than a predetermined threshold value, which is an allowable value, the rotation speed of the spindle 40 can be changed to a stable rotation speed. Also, if the spindle load is higher than a predetermined threshold value, which is an allowable value, the feed rate can be reduced, or the amount of cutting of the cutting blade of the tool T into the workpiece can be reduced.

[0055] The stable spindle rotation speed can be automatically calculated by the machining condition correction unit 18. The machining condition correction unit 18 acquires the regenerative chatter vibration frequency from the memory unit 20, accesses the process list creation unit 12 to acquire the number of teeth (number of cutting edges) of the tool causing the regenerative chatter vibration, and calculates the stable spindle rotation speed using the following formula based on the regenerative chatter vibration frequency and the number of teeth.

[0056] Stable rotation speed = (60 × regenerative chatter frequency / number of tool teeth × (k value + 1)) (1) where k is an integer value equal to or greater than 0. The stable rotation speed can be calculated by substituting k = 0, 1, 2, 3, 4, ... into equation (1) in that order.

[0057] The calculated stable spindle rotation speeds can be displayed on the display unit 24. The operator looks at the stable spindle rotation speeds displayed on the display unit 24, selects a stable spindle rotation speed that is closest to the current spindle rotation speed, and inputs it from the machining condition input unit 26 to the NC device 52 to correct the spindle rotation speed as a machining condition. Alternatively, when the stable spindle rotation speeds are displayed on the display unit 24, a dialog box (not shown) may be opened at the same time to prompt the operator to correct the spindle rotation speed, and the stable spindle rotation speed may be directly input from the machining condition correction unit 18 to the NC device 52 by the operator tapping a button in the dialog box.

[0058] After the correction, the flow chart returns to step S20, where the workpiece W is machined again, and steps S22 to S28 are executed again to determine whether the machining conditions need to be corrected. Steps S10 to S30 can be repeatedly executed until it is determined in step S28 that the machining conditions do not need to be corrected (No in step S28).

[0059] In the embodiment described above, the load information, feed rate, and spindle rotation speed are described as being obtained while the NC machine tool 30 is actually machining the workpiece W, but the present invention is not limited to this, and the load information, feed rate, and spindle rotation speed may be obtained based on the results of a simulation using a simulator (not shown). In other words, in Figure 1, the NC machine tool 30, NC device 52, and data processing unit 22 can be replaced by a simulator such as a personal computer.

[0060] In the flowchart of Fig. 6, the load information and machining conditions (feed rate and spindle rotation speed) are acquired based on the measurement results obtained by actually machining the workpiece W, but as described above, they may also be acquired by performing simulated machining using a simulator. Fig. 7 shows a flowchart of a machining condition correction method when the load information and machining conditions (feed rate and spindle rotation speed) are acquired using a simulator.

[0061] The machining program and three-dimensional shape data of the workpiece W before machining are loaded into the simulator (step S40), and the simulator executes simulated machining according to the loaded machining program to generate load information and machining conditions (feed rate and spindle rotation speed) as machining simulation data (step S42). Next, when the operator taps the machining condition correction button 106, a machining condition correction window 100 is displayed on the display unit 24 based on the load information and machining conditions (feed rate and spindle rotation speed) generated as machining simulation data, and a process list and a tool path image are displayed in the machining condition correction window 100 (step S44). Steps S46 to S50 are the same as steps S26 to S30 in FIG. 6, and therefore will not be described here.

[0062] As described above, in the present invention, it is possible to easily find a process in which a problem is occurring, since the process list and the tool path image are displayed in conjunction with each other in the machining condition correction window 100. A method for identifying a machining portion in which a problem is occurring from the tool path image and checking the tool, load information, and machining conditions (feed rate and spindle rotation speed) for machining that machining portion in the process list will be described with reference to the flowchart shown in Fig. 8.

[0063] When an operator discovers an abnormality, such as a defective machined surface or poor accuracy, in a specific portion of a workpiece that has been actually machined or generated by simulated machining using a simulator (step S60), the operator opens the machining condition correction window 100, checks whether there is an abnormality in the load information for the corresponding portion of the tool path image where the abnormality occurred, and taps on that portion (step S62). This causes the collaboration unit 16 to instruct the process list creation unit 12 to highlight the process corresponding to the portion selected by the operator (step S64). The operator can then identify the cause of the problem by checking the tool number, machining conditions, and load information for the highlighted process (step S66).

[0064] Conversely, it is also possible to identify a problematic process from the process list and check the corresponding portion on the tool path image. Referring to the flowchart shown in FIG. 9 , when the operator discovers an abnormality, such as a poorly machined surface or poor accuracy, in a specific portion of a workpiece actually machined or generated by simulated machining using a simulator, or when the operator wants to further improve the machining conditions (step S70), the operator opens the machining condition correction window 100 and taps the problematic process or a process that can be improved from the process list (step S72). This causes the linking unit 16 to instruct the tool path image generator 14 to highlight the tool path corresponding to the process selected by the operator (step S74). By referring to the highlighted tool path, the operator can identify the machining conditions that are causing the problem.

[0065] REFERENCE SIGNS LIST 10 Machining condition correction support device 12 Process list creation unit 14 Tool path image generation unit 16 Linkage unit 18 Machining condition correction unit 20 Storage unit 22 Data processing unit 24 Display unit 26 Machining condition input unit 30 NC machine tool 52 NC device 100 Machining condition correction window 200 Process list window 300 Tool path window

Claims

1. A device for supporting the correction of machining conditions in an NC machine tool that inputs a machining program and machining conditions into an NC device and machines a workpiece by sequentially changing tools, comprising: a data processing unit that calculates at least one piece of data for load information during workpiece machining; a memory unit that stores data calculated by the data processing unit for each process during workpiece machining; a process list creation unit that creates a process list including at least one piece of data for load information for each process based on the data stored in the memory unit during or after workpiece machining; a tool path image creation unit that creates a tool path image by superimposing data from the memory unit on moment-by-moment tool path data during or after workpiece machining; and a linking unit that links the process list and the tool path image and displays them on a display unit.

2. The machining condition correction support device for an NC machine tool according to claim 1, wherein said data processing unit calculates at least one piece of load information by actually measuring the workpiece while it is being machined by said NC machine tool.

3. The machining condition correction support device for an NC machine tool according to claim 1, wherein said data processing section performs a machining simulation of a workpiece by said NC machine tool and calculates at least one piece of load information data at that time.

4. A machining condition correction support device for an NC machine tool as described in any one of claims 1 to 3, wherein the data processing unit calculates a spindle load or vibration value as load information, and the process list creation unit creates a process list including at least one of data on the maximum value of the spindle load for each process and the presence or absence of regenerative chatter vibration.

5. A machining condition correction support device for an NC machine tool as described in claim 1, wherein when a tool number in the process list is selected, the linking unit causes the tool path image generating unit to highlight the corresponding location in the tool path image machined with that tool.

6. A machining condition correction support device for an NC machine tool as described in claim 1, further comprising a machining condition correction unit that calculates a stable spindle rotation speed that suppresses regenerative chatter vibration based on the vibration frequency and the number of tool teeth, and displays the stable spindle rotation speed on the display unit.

7. A machining condition correction support device for an NC machine tool as described in claim 1, further comprising a machining condition correction unit that calculates a stable spindle rotation speed that suppresses regenerative chatter vibration based on the vibration frequency and the number of tool teeth, and outputs the stable spindle rotation speed to the NC device.

Images