Processed bore diameter prediction system and processed bore diameter prediction method

Abstract

To provide a processed bore diameter prediction system that predicts a processed bore diameter with high precision and displays the predicted value at a display part in finished hole processing using a boring tool.SOLUTION: A processed bore diameter prediction system comprises: a measurement part which measures a current value of a drive part rotating the main shaft of a processing device and outputs a measurement signal during processing on a ground material; a measurement signal storage part which stores the measurement signal; a tool diameter information storage part which stores a tool diameter measured value of a tool used to processing the ground material; a signal processing part which determines a signal in an object processing stage with respect to the measurement signal; a variation quantity calculation part which calculates a reflection value of a processing load with the signal determined as the signal in the object processing stage, and calculates a predicted value of a variation quantity from the tool diameter of a processed bore with the calculated reflection value of the processing load; a processed bore diameter calculation part which adds together the predicted value of the variation quantity from the tool diameter of the processed bore calculated by the variation quantity calculation part and the tool diameter measured value stored in the tool diameter information storage part to calculate a processed bore diameter predicted value; and a display part which displays the processed bore diameter predicted value calculated by the processed bore diameter calculation part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a system and method for predicting the diameter of a hole after machining a workpiece by a machining device, and in particular to a technique that is effective when applied to a machining device having a boring tool. [Background technology]

[0002] In machining centers and other processing equipment, boring tools are used for finishing high-precision holes. The cutting edge of the boring tool is moved radially relative to the center of the tool to adjust the tool diameter. The tool diameter of the boring tool is adjusted outside the processing equipment using a tool presetter or the like.

[0003] In the rough machining before the finish machining, the machining dimensional tolerance range is large, and the hole diameter after the rough machining has a large variation. This causes variation in the adjusted tool diameter in the finish hole machining. Therefore, after the finish machining, it is necessary to measure the hole diameter using a contact type inner diameter micrometer or the like to check whether it is within the dimensional tolerance range. In addition, the contact of the measuring device at that time may scratch the machined surface, resulting in a machining defect.

[0004] As a machined surface shape prediction device after cutting using a processing device, for example, a technology such as that described in Patent Document 1 is known. Patent Document 1 describes "a machined surface shape prediction device having a coordinate value acquisition unit that acquires the position coordinate value of a tool in a processing machine during processing, a processing load acquisition unit that acquires the processing load on a drive shaft of the processing machine during processing, and a prediction processing unit that calculates the amount of deformation of the tool due to the processing load and predicts the machined surface shape from the amount of deformation and the position coordinate value." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-99590 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned Patent Document 1, the rigidity of the tool is obtained, the deformation amount of the tool due to the machining load is calculated, and the machined surface shape is predicted.

[0007] However, the boring tool has a cutting edge movement function for adjusting the tool diameter and is composed of multiple parts, so it is difficult to obtain the rigidity of the boring tool itself with high accuracy, and the deformation amount of the tool cannot be calculated with high accuracy using the rigidity of the tool from the acquired machining load, so there is a high possibility that the predicted value of the machined surface shape will have a large error from the actual measured value.

[0008] When the difference between the calculated predicted value and the actual measured value is large, it is necessary to measure the hole diameter using a contact type inner diameter micrometer or the like to confirm the dimensions. Therefore, in finish hole machining using a boring tool, the challenge is to predict the hole diameter after machining with high accuracy.

[0009] Therefore, an object of the present invention is to provide a machined hole diameter prediction system and a machined hole diameter prediction method that predict the machined hole diameter with high accuracy and display the predicted value on a display unit in finish hole machining using a boring tool by a machining device. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention is characterized in that it comprises a measurement unit that measures the current value of a drive unit that rotates a spindle of a machining device while the machining device is machining a workpiece and outputs a measurement signal, a measurement signal memory unit that stores the measurement signal, a tool diameter information memory unit that stores tool diameter measurement values ​​of a tool used to machine the workpiece, a signal processing unit that determines a signal of a target machining process in the measurement signal, a change amount calculation unit that calculates a reflected value of a machining load from a signal determined to be a signal of the target machining process and calculates a predicted value of change from the tool diameter of a machined hole from the calculated reflected value of the machining load, a machined hole diameter calculation unit that calculates a predicted value of change from the tool diameter of the machined hole calculated by the change amount calculation unit and the tool diameter measurement value stored in the tool diameter information memory unit, and a display unit that displays the predicted value of machined hole diameter calculated by the machined hole diameter calculation unit.

[0011] The present invention also provides a machined hole diameter prediction method for predicting a machined hole diameter after machining of a workpiece by a machining device, comprising the steps of: (a) measuring a current value of a drive unit that rotates a spindle of the machining device while the workpiece is being machined by the machining device to obtain a measurement signal; (b) determining a signal of a target machining process from the measurement signal obtained in step (a); (c) calculating a reflected value of a machining load from the signal determined to be a signal of a target machining process in step (b), and calculating a predicted value of a change from the tool diameter of the machined hole from the calculated reflected value of the machining load; (d) calculating a predicted value of a machined hole diameter by adding the predicted value of a change from the tool diameter of the machined hole calculated in step (c) to a measured value of the tool diameter of a tool used to machine the workpiece; and (e) displaying the predicted value of a machined hole diameter calculated in step (d). Effect of the Invention

[0012] According to the present invention, it is possible to realize a machined hole diameter prediction system and a machined hole diameter prediction method that predict the machined hole diameter with high accuracy and display the predicted value on a display unit in finish hole machining using a boring tool by a machining device.

[0013] This eliminates the need for manual measurement using a contact-type measuring device after finishing hole processing, improving productivity. In addition, it also reduces the defect rate because scratches on the processed surface caused by contact-type measuring devices are no longer generated.

[0014] Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing a schematic configuration of a machined hole diameter prediction system according to a first embodiment of the present invention. [Diagram 2] 4 is a flowchart showing a machined hole diameter prediction method according to the first embodiment of the present invention. [Diagram 3] FIG. 11 is a diagram showing the time change of a spindle motor current during finish hole machining. [Figure 4] FIG. 13 is a diagram showing the change over time in the effective value of the spindle motor current during finish hole machining. [Diagram 5] FIG. 5 is an enlarged view of a portion of FIG. 4. [Figure 6] FIG. 13 is a diagram showing the relationship between the spindle motor current ΔI and the amount of change in the machined hole from the tool diameter in finish hole machining. [Figure 7] 2 is a diagram showing an example of a display (GUI screen) on the display unit in FIG. 1; FIG. [Figure 8] 2 is a diagram showing an example of a display (GUI screen) on the display unit in FIG. 1; FIG. [Figure 9] 2 is a diagram showing an example of a display (GUI screen) on the display unit in FIG. 1; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are designated by the same reference numerals, and detailed description of overlapping parts will be omitted. EXAMPLES

[0017] A machined hole diameter prediction system and a machined hole diameter prediction method according to a first embodiment of the present invention will be described with reference to Figs.

[0018] In this embodiment, an example of a machined hole diameter prediction system is described in which a machining device performs finish hole machining on a workpiece using a boring tool measures the spindle motor current during machining, calculates a predicted amount of change from the tool diameter of the machined hole using the obtained spindle motor current, adds this to the tool diameter measurement value to obtain a machined hole diameter predicted value, and displays the result on a display unit.

[0019] Fig. 1 is a diagram showing a schematic and exemplary configuration of a machined hole diameter prediction system according to the present embodiment. Fig. 1 shows an example in which a machined hole diameter prediction system 1 is attached to a machining device 4. The machining process shown in Fig. 1 is an example in which a boring tool 5 is used to machine a finish hole in a workpiece 7. The machining device 4 is an NC milling machine or a machining center that can be controlled by an NC program (Numerical Control), etc.

[0020] In the processing device 4, a boring tool 5 is fixed to a spindle 6, the spindle 6 is rotated by a spindle motor 8, and the boring tool 5 and the workpiece 7 are moved and brought into contact with each other by a means (not shown) for relatively moving the boring tool 5 and the workpiece 7, thereby machining a hole of the desired dimensions in the workpiece 7. At this time, a servo amplifier 9 controls the current value input to the spindle motor 8 according to a command from an NC device 10 in which an NC program is stored. This causes the spindle motor 8 to rotate at the rotation speed as commanded. The boring tool 5 is, for example, a cutting edge-replaceable boring tool that has a function of adjusting the tool diameter by moving the cutting edge in the radial direction relative to the tool center.

[0021] The machined hole diameter prediction system 1 includes a measurement unit 14 and a machined hole diameter prediction system main body 15 as main components.

[0022] The machined hole diameter prediction system main body 15 can be configured on a general-purpose computer. Its hardware configuration includes a calculation unit 2 configured with a CPU (Central Processing Unit), RAM (Random Access Memory), etc., a storage unit 3 configured with a ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive) using flash memory, etc., an input unit 11 configured with input devices such as a keyboard and a mouse, a display unit 12 configured with a display device such as an LCD (Liquid Crystal Display) or an organic EL display, various output devices, etc., a communication unit 13 configured with a NIC (Network Interface Card), input / output interface devices, etc.

[0023] The communication unit 13 is connected to a measurement unit 14 that measures a current value between the servo amplifier 9 and the spindle motor 8 of the processing device 4 via a wired or wireless network, or via an individual dedicated cable, a USB (Universal Serial Bus) cable, etc. The measurement unit 14 is composed of a current sensor, an AD converter, etc.

[0024] The calculation unit 2 realizes each functional unit by loading the measurement program 31, signal processing program 32, change amount calculation program 33, and machined hole diameter calculation program 34 stored in the storage unit 3 into the RAM and executing them with the CPU. The calculation unit 2 has a measurement control unit 21, a measurement signal processing unit 22, a change amount prediction value calculation unit 23, and a machined hole diameter prediction value calculation unit 24.

[0025] The memory unit 3 has a memory area for storing each of the following information: a measurement program 31, a signal processing program 32, a change amount calculation program 33, a machined hole diameter calculation program 34, tool diameter information 35, a measurement signal 36, a hole machining measurement signal 37, a change amount predicted value 38, and a machined hole diameter predicted value 39.

[0026] The process flow performed by the machined hole diameter prediction system 1 of FIG. 1 will be described with reference to the example of the flowchart of FIG.

[0027] First, in step S01, the operation of the machined hole diameter prediction system 1 is started. By pressing an operation start button (described later with reference to FIG. 7) on the GUI screen of the machined hole diameter prediction system 1 displayed on the display unit 12, the operation of the machined hole diameter prediction system 1 is started.

[0028] Next, in step S02, the spindle servo motor current (hereinafter referred to as the spindle motor current) is acquired. The measurement program 31 in the memory unit 3 is executed, and the measurement control unit 21 in the calculation unit 2 continuously acquires the spindle motor current from between the servo amplifier 9 and the spindle motor 8, and stores it in the measurement signal 36 in the memory unit 3 via the communication unit 13.

[0029] Next, in step S03, the signal processing program 32 in the memory unit 3 is executed, and it is determined whether the spindle motor current signal stored in the measurement signal 36 in the measurement signal processing unit 22 of the calculation unit 2 is a finish hole machining signal. If it is determined to be finish hole machining data (Yes), it is stored in the hole machining measurement signal 37 in the memory unit 3. If the machining time of finish hole machining is different from the machining time of other machining processes, the finish hole machining data is determined based on the elapsed time from the start to the end of machining (machining time). Also, if the finish hole machining has a different rotation speed or number of tool teeth from other tools and frequency components specific to finish hole machining appear in the spindle motor current, it may be determined by frequency analysis. On the other hand, if it is determined to not be finish hole machining data (No), the process returns to step S02 and repeats the processes from step S02 onwards.

[0030] Next, in step S04, a predicted change value from the tool diameter of the hole machined by the spindle motor current (hereinafter referred to as the machined hole) is calculated. The change value calculation program 33 in the storage unit 3 is executed, and a reflected value of the machining load, described below, is calculated in the spindle motor current for finish hole machining stored in the hole machining measurement signal 37 in the change value prediction value calculation unit 23 of the calculation unit 2, and further a predicted change value from the tool diameter of the machined hole is calculated using a change value prediction formula based on the spindle motor current derived in advance, described below. The calculated predicted change value is stored in the predicted change value 38 in the storage unit 3.

[0031] Next, in step S05, the machined hole diameter calculation program 34 in the memory unit 3 is executed, and the machined hole diameter predicted value calculation unit 24 of the calculation unit 2 calculates a machined hole diameter predicted value by adding the tool diameter measurement value stored in the tool diameter information 35 in the memory unit 3 to the predicted amount of change from the tool diameter of the machined hole stored in the predicted amount of change 38. The calculated machined hole diameter predicted value is stored in the machined hole diameter predicted value 39 in the memory unit 3.

[0032] Finally, in step S06, the predicted machined hole diameter value stored in predicted machined hole diameter value 39 is outputted and displayed on display unit 12. Thereafter, the process returns to step S02, and the processes from step S02 onwards are repeated.

[0033] In addition, the tool diameter information 35 is input with the tool diameter measurement value measured when the tool diameter of the boring tool 5 is set by the input unit 11 before the machined hole diameter prediction system 1 is operated.

[0034] FIG. 3 is a diagram showing the change over time in the spindle motor current during finish hole machining.

[0035] This is signal data that is determined to be a finish hole machining signal by the measurement signal processing unit 22 of the calculation unit 2 in step S03 of Fig. 2 and stored in the hole machining measurement signal 37 of the memory unit 3. This is an example in which a single-blade Φ200 mm boring tool 5 is used to finish a 40 mm deep hole in a stainless steel workpiece 7. The machining conditions are a spindle rotation speed of 110 min -1 The feed rate was 130 mm / min, the diameter cutting depth was 0.11 mm, and the tool diameter measurement value of the boring tool 5 was Φ200.021 mm. The measurement conditions were a sampling time of 0.001 seconds.

[0036] In the waveform of the spindle motor current shown in Fig. 3, large amplitudes can be seen at machining times of approximately 5 seconds and approximately 218 seconds. Amplitude 40 is the current for starting the motor when the spindle 6 starts to rotate, and amplitude 41 is the current for stopping the motor when the spindle 6 stops to rotate. Therefore, the range between amplitude 40 and amplitude 41 is the signal data of the spindle motor current for finish hole machining.

[0037] FIG. 4 is a diagram showing the change over time in the effective value of the spindle motor current during finish hole machining.

[0038] This is the effective value of the spindle motor current shown in Fig. 3. This is the data used to determine that the signal is for finish hole machining by the measurement signal processing unit 22 of the calculation unit 2 in step S03 in Fig. 2. The effective value is calculated at 0.2 second intervals.

[0039] In the waveform of the effective value of the spindle motor current shown in Fig. 4, the current rises sharply when the spindle 6 starts rotating at about 5 seconds into the machining time, and then remains constant at about 20 A. Then, after increasing at about 30 seconds into the machining time, it remains almost constant, and then rises sharply once at about 218 seconds into the machining time when the rotation stops, before decreasing to about 2 A.

[0040] In the range 46 from amplitude 43 at the start of spindle rotation to increase point 45 at a machining time of approximately 30 seconds, the spindle 6 is in an idling state. When the boring tool 5 comes into contact with the workpiece 7 at increase point 45 and machining begins, a load is generated on the spindle 6, and control is applied from the servo amplifier 9 to rotate the spindle motor 8 at a constant rotation speed, increasing the current value detected by the measurement unit 14. The range 47 from the increase point 45 to just before amplitude 44 when the spindle rotation stops is the effective value data of the spindle motor current for finish hole machining.

[0041] The signal determination process of the finish hole machining in the measurement signal processing unit 22 of the calculation unit 2 in step S03 shown in FIG. 2 will be described with reference to FIGS.

[0042] The measurement signal processing unit 22 first calculates the effective value of the spindle motor current signal stored in the measurement signal 36 at any interval. Here, the calculation is performed at 0.2 second intervals as described above. Then, when the calculated effective value exceeds the threshold value 42, it is determined that the spindle 6 has rotated, and when the effective value of the spindle motor current thereafter becomes smaller than the threshold value 42, it is determined that the rotation of the spindle 6 has stopped and machining has ended.

[0043] The time elapsed from the start to the stop of rotation of the spindle 6 is set as the machining time, and if the machining time is within the finish hole machining judgment time range, it is judged to be a finish hole machining signal. Here, a machining time between 215 seconds and 225 seconds is judged to be a finish hole machining signal. Thereafter, if it is judged to be a finish hole machining signal, it is stored in the hole machining measurement signal 37 of the memory unit 3. Here, if it is judged to be a finish hole machining signal, data for 5 seconds before and after the machining time is added, and the measurement signal (raw data) of the spindle motor current and the effective value data of the spindle motor current are stored in the hole machining measurement signal 37.

[0044] Fig. 5 is a diagram showing the time change of the effective value of the spindle motor current in finish hole machining with the vertical axis enlarged. This is Fig. 4 with the vertical axis enlarged to 20-23 A. The data is also used to predict the amount of change from the tool diameter of the machined hole by the change amount prediction value calculation unit 23 of the calculation unit 2 in step S04 shown in Fig. 2.

[0045] To predict the amount of change from the tool diameter of the machined hole, a difference 50 between the average value of the spindle idling range 46 and the average value of the finish hole machining range 47 was used. Hereinafter, this difference 50 will be referred to as the spindle motor current ΔI. The spindle motor current ΔI is a value that reflects the machining load. The spindle motor current during idling of the machining device 4 may fluctuate due to the influence of temperature changes in the environment in which it is installed. In this way, by determining the difference between the spindle motor current during idling and the spindle motor current during machining, it is possible to suppress the influence of disturbances and use data that reflects the machining load during finish hole machining with high accuracy.

[0046] Fig. 6 is a diagram showing the relationship between the spindle motor current ΔI and the amount of change in the hole diameter from the tool diameter during finish hole machining. This is a measurement result showing the relationship between the spindle motor current ΔI and the amount of change in the machined hole from the tool diameter when finish machining is performed with the hole diameter range from the maximum to the minimum in three stages during rough machining. Hereinafter, the amount of change in the machined hole from the tool diameter will be referred to as ΔD.

[0047] Here, the rough hole diameter dimension range is Φ199.85±0.1mm, so the rough hole diameters were machined to Φ199.75, Φ199.85mm, and Φ199.95mm. The change in the tool diameter of the machined hole ΔD indicates the difference between the hole diameter measured with an inner diameter micrometer after finish machining and the tool diameter measurement of the boring tool. The hole diameter after machining is the average value of a total of six points measured in orthogonal directions (two directions) at three hole depths (10mm, 20mm, 30mm). The tool diameter measurement of boring tool 5 was Φ200.024mm.

[0048] In FIG. 6, an approximation curve 51 is a regression line obtained by the least squares method using the spindle motor current ΔI and the amount of change ΔD from the tool diameter of the machined hole, and is expressed by the following approximation formula (1).

[0049] ΔD=0.0455×ΔI-0.0068 (1) The coefficient of determination for this approximation formula (1) is 0.94, which means that it can be said to be able to well explain the change amount ΔD from the tool diameter of the machined hole, which is the objective variable, with the spindle motor current ΔI as the explanatory variable. Therefore, this approximation formula (1) was used as the prediction formula for the change amount ΔD from the tool diameter of the machined hole due to the spindle motor current ΔI.

[0050] It should be noted that the prediction formula (1) needs to be derived each time when the tool shape, the material of the workpiece 7, the machining conditions, etc. are different. Here, the hole diameter of the rough machining was adjusted to change the amount of cutting in the diameter, and the prediction formula for the change amount ΔD of the machined hole from the tool diameter due to the spindle motor current ΔI was experimentally derived, but it can also be obtained by accumulating data on the dimensional inspection results and the corresponding tool diameter and spindle motor current during product machining. In addition, the derived prediction formula may be corrected by accumulating data after derivation. In addition, the prediction formula was derived by regression analysis using the least squares method, but it may be derived from another analysis method as long as the change amount ΔD of the machined hole from the tool diameter due to the spindle motor current ΔI can be predicted with high accuracy.

[0051] Also, in Figure 6, the larger the spindle motor current ΔI, the larger the change ΔD in the machined hole from the tool diameter tends to be. This result shows that the hole diameter after finish machining is larger when the rough machining hole diameter is small and the finishing hole machining depth is large. This is because the cutting angle of the boring tool 5 used is 90 degrees or more, and the thrust force of the cutting force generated on the cutting edge of the tool during machining is directed toward the workpiece. The larger the machining load, the greater the force pulling the tool toward the workpiece 7, and the larger the machined hole diameter tends to be.

[0052] On the other hand, when the cutting angle is less than 90 degrees, the thrust force of the cutting force generated on the cutting edge of the tool during machining is directed toward the tool, so that as the machining load increases, a force acts on the tool in a direction away from the workpiece 7, and the hole diameter tends to become smaller. Therefore, as mentioned above, when the tool shape changes, a new prediction formula must be derived.

[0053] Next, an operation screen displayed on the display unit 12 of the machined hole diameter prediction system 1 will be described using an example of a configuration diagram.

[0054] FIG. 7 is an example of a configuration diagram of a GUI (Graphical User Interface) screen of the display unit 12 in the machined hole diameter prediction system 1 shown in FIG.

[0055] The GUI screen 101 includes an operation start button 102 for starting operation of the machined hole diameter prediction system 1, an operation interrupt button 103 for ending operation, a tool diameter input section 104 for inputting the tool diameter measurement value of the boring tool 5, a machined hole diameter predicted value display section 105, and a predicted change amount from tool diameter display section 106. The predicted change amount from the tool diameter predicted using the spindle motor current acquired during hole machining is displayed in the predicted change amount display section 106, and the predicted machined hole diameter is displayed in the predicted machined hole diameter display section 105.

[0056] FIG. 7 shows an example of the results of finish machining using a Φ200 mm boring tool 5. This is the machined hole diameter prediction result of the spindle motor current shown in FIG. 3 to FIG. 5. The machined hole diameter prediction value is Φ200.051 mm, while the actual machined hole diameter is Φ200.056 mm, with an error of -0.005 mm. In this finish hole machining, the machining dimensional tolerance range is Φ200.00 to Φ200.10 mm (Φ200.05 ±0.05 mm). The predicted accuracy (error) of the hole diameter is ±10% or less (±0.01 mm or less) with respect to the hole diameter tolerance range of 0.10 mm, and it can be used for dimensional inspection of the machined hole diameter.

[0057] Therefore, since the machined hole diameter can be confirmed after machining by the machined hole diameter prediction system 1, it can replace the manual inspection process after finish machining, and the inspection process can be omitted. In addition, since there is no scratch on the machined surface that may be caused by a contact type measuring device, the occurrence rate of machining defects can be reduced.

[0058] Fig. 8 is another example of a GUI screen displayed on the display unit 12 of the machined hole diameter prediction system 1. In addition to the configuration of Fig. 7, the GUI screen 110 further includes a hole diameter prediction value warning light 111. When the machined hole diameter prediction value predicted using the spindle motor current exceeds ±70% of the machining dimensional tolerance, the hole diameter prediction value warning light 111 turns on.

[0059] Figure 8 shows an example of the result of finish machining using a Φ200mm boring tool 5. The dimensional tolerance of the finish machining of the machined hole is 200.00 to Φ200.10m (Φ200.05±0.05mm), as in Figure 7. Here, the predicted hole diameter warning light 111 is set to light up when the predicted machined hole diameter is Φ200.085mm (tolerance +70%) or more, or Φ200.015mm (tolerance -70%) or less.

[0060] In Figure 8, the hole diameter was predicted to be Φ200.087mm, so the hole diameter prediction warning light 111 is on. The actual measurement value of this finish hole machining was Φ200.083mm, and the prediction error was +0.004mm. The reason why the hole diameter of the finish machining is larger is because the hole diameter of the rough machining was reduced to Φ199.69mm, which increased the processing load of the finish machining.

[0061] Similarly, in product machining, if the predicted hole diameter value for finish machining approaches the limit of the tolerance range, the rough machining dimensions may be outside the tolerance range, so it is possible to prompt a review of the rough machining tools and machining conditions, or to check the tool diameter setting of the boring tool 5 for finish machining. This makes it possible to stabilize the dimensions of the finish hole machining. Note that the dimensional tolerance range for issuing a warning is set here as being when it exceeds ±70%, but it can be set arbitrarily.

[0062] 9 is yet another example of a GUI screen displayed on the display unit 12 of the machined hole diameter prediction system 1. The GUI screen 121 includes display units 122a-122c for predicted machined hole diameter values ​​for a plurality of hole depths and a display unit 122d for their average value, and display units 123a-123c for predicted values ​​of changes from the tool diameter and a display unit 123d for their average value.

[0063] For the spindle motor current ΔI, data corresponding to 5 to 15 mm for a hole depth of 10 mm, 15 to 25 mm for a hole depth of 20 mm, and 25 to 35 mm for a hole depth of 30 mm were extracted and the average value was calculated. A predicted amount of change from the tool diameter of the machined hole for each hole depth was calculated and added to the tool diameter to obtain the predicted machined hole diameter for each hole depth.

[0064] FIG. 9 shows an example of the results of finish machining using a Φ200 mm boring tool 5. This shows the predicted machined hole diameter values ​​and their average values ​​for each hole depth at the spindle motor currents shown in FIGS. 3 to 5. The difference between the predicted and actual values ​​for each hole depth was -0.005 to -0.006 mm. This predicted machined hole diameter value was calculated using prediction formula (1) for the amount of change ΔD from the tool diameter of the machined hole, and by finding the average value using data corresponding to the hole depth at the spindle motor current ΔI, it is possible to predict the machined hole diameter with high accuracy for each hole depth.

[0065] According to this embodiment, in finish hole machining using a boring tool 5 in a machining device 4, the amount of change from the tool diameter of the automatically machined hole is predicted based on the acquired spindle motor current, and this is added to the tool diameter measurement value to obtain a highly accurate predicted value of the machined hole diameter, and furthermore, the result is displayed on the display unit, so that the machining dimensions can be checked after machining.

[0066] This can replace the manual inspection process after finishing, making it possible to omit the inspection process. In addition, it also eliminates scratches on the processed surface that may be caused by contact-type measuring devices, which has the effect of reducing the occurrence of processing defects.

[0067] In this embodiment, an example is shown in which the spindle motor current is measured by the measuring unit 14, but depending on the processing machine, the spindle motor current can be acquired by connecting a PC (personal computer) via an Ethernet (registered trademark) line and using a measurement application. That is, there is no problem with a configuration in which the function of the measuring unit 14 is included in the calculation unit 2 of the machined hole diameter prediction system main body 15 in FIG. 1.

[0068] Furthermore, the present invention is not limited to the above-mentioned embodiment, and various modifications are included. For example, the above-mentioned embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to those having all of the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0069] 1...machined hole diameter prediction system, 2...calculation unit, 3...memory unit, 4...machining device, 5...boring tool, 6...spindle, 7...workpiece, 8...spindle motor, 9...servo amplifier, 10...NC device, 11...input unit, 12...display unit, 13...communication unit, 14...measurement unit, 15...machined hole diameter prediction system main body, 21...measurement control unit, 22...measurement signal processing unit, 23...change amount predicted value calculation unit, 24...machined hole diameter predicted value calculation unit, 31...measurement program, 32...signal processing program, 33...change amount calculation program, 34...machined hole diameter calculation program, 35...tool diameter information, 36...measurement signal, 37...hole machining measurement signal, 38...deformation amount predicted value, 39...machined hole diameter predicted value, 4 0...Amplitude at the start of spindle rotation, 41...Amplitude at the stop of spindle rotation, 42...Threshold value, 43...Amplitude at the start of spindle rotation, 44...Amplitude at the stop of spindle rotation, 45...Increase point, 46...Spindle idling range, 47...Finish hole machining range, 50...Spindle motor current ΔI, 51...Approximate curve, 101, 110, 121...GUI screen, 102...Start operation button, 103...Operation interruption button, 104...Tool diameter input section, 105...Predicted hole diameter display section, 106...Predicted change from tool diameter display section, 111...Predicted hole diameter warning light, 122, 122a to 122d...Predicted hole diameter display section, 123, 123a to 123d...Predicted change from tool diameter display section.

Claims

1. a measuring unit that measures a current value of a drive unit that rotates a spindle of a processing device while the processing device is processing a workpiece, and outputs a measurement signal; a measurement signal storage unit that stores the measurement signal; a tool diameter information storage unit that stores tool diameter measurement values ​​of a tool used to machine the workpiece; A signal processing unit that determines a signal of a target processing step in the measurement signal; a change amount calculation unit that calculates a reflected value of a machining load based on the signal determined to be a signal of the target machining process, and calculates a predicted change amount from a tool diameter of a machined hole based on the calculated reflected value of the machining load; a machined hole diameter calculation unit that calculates a machined hole diameter predicted value by adding a change amount predicted value from the tool diameter of the machined hole calculated by the change amount calculation unit and a tool diameter measurement value stored in the tool diameter information storage unit; a display unit that displays the predicted machining hole diameter calculated by the machining hole diameter calculation unit; A machined hole diameter prediction system comprising:

2. The machined hole diameter prediction system according to claim 1, The tool is a boring tool with an adjustable tool diameter, A machined hole diameter prediction system, comprising: a tool diameter adjustment unit that adjusts the tool diameter before machining a workpiece by a machining device; and inputs the adjusted tool diameter measurement value into the tool diameter information storage unit.

3. The machined hole diameter prediction system according to claim 1, the measurement signal is a spindle motor current; A machined hole diameter prediction system, characterized in that the reflected value of the machining load in the measurement signal is the difference between the average value when the spindle is idling and the average value during hole machining.

4. The machined hole diameter prediction system according to claim 1, A machined hole diameter prediction system characterized in that the predicted value of the change in the tool diameter of the machined hole is calculated using a prediction formula derived in advance from the reflected value of the machining load in the measurement signal and the measured value of the change in the tool diameter.

5. The machined hole diameter prediction system according to claim 1, A machined hole diameter prediction system, characterized in that if the machined hole diameter prediction value falls outside a preset dimensional range, a warning light is turned on in the display unit.

6. The machined hole diameter prediction system according to claim 1, A machined hole diameter prediction system, characterized in that the display unit displays machined dimension predicted values ​​corresponding to a plurality of hole depths.

7. A method for predicting a machined hole diameter after machining a workpiece by a machining device, comprising: (a) measuring a current value of a drive unit that rotates a spindle of a processing device while the processing device is processing a workpiece to obtain a measurement signal; (b) determining a signal of a target processing step in the measurement signal obtained in the step (a); (c) calculating a reflected value of a machining load based on the signal determined to be a signal of a target machining process in the (b) step, and calculating a predicted value of a change in a tool diameter of a machined hole based on the calculated reflected value of the machining load; (d) calculating a predicted machining hole diameter by adding a predicted change amount from the tool diameter of the machined hole calculated in the (c) step and a measured tool diameter value of a tool used to machine the workpiece; (e) displaying the predicted hole diameter calculated in the step (d); A method for predicting a machined hole diameter comprising:

8. The method for predicting a machined hole diameter according to claim 7, The tool is a boring tool with an adjustable tool diameter, (f) A method for predicting a machined hole diameter, further comprising a step of adjusting the tool diameter before machining a workpiece by a machining device and inputting the adjusted tool diameter measurement value.

9. The method for predicting a machined hole diameter according to claim 7, the measurement signal is a spindle motor current; The method for predicting a machined hole diameter, wherein the reflected value of the machining load in the step (c) is a difference between an average value when the spindle is idling and an average value during hole machining.

10. The method for predicting a machined hole diameter according to claim 7, a predicted value of the change in the machined hole from the tool diameter in the step (c) is calculated using a prediction formula derived in advance from a reflected value of the machining load in the measurement signal and a measured value of the change in the tool diameter.

11. The method for predicting a machined hole diameter according to claim 7, A method for predicting a machined hole diameter, comprising the steps of: lighting a warning light on a display unit when the predicted machined hole diameter value falls outside a preset dimensional range.

12. The method for predicting a machined hole diameter according to claim 7, The method for predicting a machined hole diameter, wherein in the step (e), predicted machining dimension values ​​corresponding to a plurality of hole depths are displayed.

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