Grinding system

Abstract

To provide a grinding system which can exactly detect a grinding burn depth which remains on a surface of a ground workpiece.SOLUTION: A grinding system calculates a current grinding burn depth A (A1, A2), and calculates a position moved to a reference position C side as a temporary grinding burn deepest position Pa (Pa1, Pa2) by a magnitude of the current grinding burn depth A (A1, A2) at an objective grinding time from a surface position D of a workpiece W at the objective grinding time. Then, by comparing the temporary grinding burn deepest position Pa (Pa1, Pa2) at the calculated objective grinding time with a remaining grinding burn deepest position P at a previous objective grinding time of a same processed part of the workpiece W, the grinding system updates the position approximate to the reference position C as the remaining grinding burn deepest position P at a current objective grinding time.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a grinding system.

Background Art

[0002] Conventionally, when machining a workpiece by grinding, the temperature of the machining part on the workpiece tends to become high. Therefore, depending on the machining conditions, grinding burn may occur on the surface of the workpiece. Grinding burn is not preferable because it may cause a decrease in the mechanical strength of the workpiece. As a method for detecting such grinding burn, for example, in Patent Document 1, it is utilized that the change in the magnetic field due to the eddy current generated in the workpiece by the exciting current differs depending on the presence or absence of grinding burn. Eddy currents are generated in the workpiece by a plurality of exciting currents having different frequencies, and by detecting the difference in the change in the magnetic field due to the eddy currents in the deep part and the surface layer part of the workpiece, a configuration for detecting the grinding burn in the surface layer part of the workpiece is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration disclosed in Patent Document 1, it is difficult to accurately detect to what depth the grinding burn has reached on the surface layer of the workpiece, that is, the grinding burn depth. If the grinding burn depth cannot be accurately detected, it is difficult to adjust the grinding conditions to prevent grinding burn, leading to a decrease in productivity. Therefore, accurately detecting the grinding burn depth is required.

[0005] The present invention aims to provide a grinding system capable of accurately detecting the grinding burn depth remaining on the surface of a machined workpiece. [Means for solving the problem]

[0006] One aspect of the present invention is a grinding system for processing a workpiece surface to a final target shape by grinding it multiple times, Actual depth of cut when grinding the above workpiece The change in the dimensions of the outer surface of the workpiece when the workpiece is ground once. A unit for acquiring the actual cutting depth, Grinding state quantities related to grinding the above workpiece The power of the tool for grinding the surface of the workpiece, the tangential and normal resistance of the tool to the workpiece, the temperature of the machining point on the workpiece, the temperature of the coolant supplied to the machining point, and the flow rate of the coolant are at least one of these. A grinding state quantity acquisition unit that acquires the grinding state quantity, A correspondence relationship storage unit pre-stores the correspondence between the actual depth of cut when the above workpiece is ground, the grinding characteristic quantity extracted from the grinding state quantity when the above workpiece is ground, and the grinding burn depth that occurs on the workpiece due to grinding at the grinding time from which the grinding characteristic quantity was extracted. A current grinding burn depth estimation unit estimates the grinding burn depth that occurs on the workpiece at each grinding time due to grinding under the grinding conditions at each grinding time, based on the actual depth of cut acquired by the actual depth of cut acquisition unit, the grinding state amount acquired by the grinding state amount acquisition unit, and the correspondence stored in the correspondence relationship storage unit, as the current grinding burn depth A. A provisional grinding burn depth calculation unit calculates a provisional grinding burn depth Pa, which is a provisional value of the deepest grinding burn position occurring on the workpiece at the target grinding time, by moving from the surface position D of the workpiece at the target grinding time by the amount of the current grinding burn depth A estimated by the current grinding burn depth estimation unit towards the reference position C set inside the workpiece at the target grinding time. A storage unit for the deepest residual grinding burn position P, which is the deepest position of grinding burn remaining on the workpiece, A residual grinding burn deepest position update unit compares the provisional grinding burn deepest position Pa of the grinding burn in the workpiece, calculated by the provisional grinding burn deepest position calculation unit at the target grinding time, with the residual grinding burn deepest position P of the same workpiece at the previous target grinding time, which is stored in the residual grinding burn deepest position storage unit, and updates the residual grinding burn deepest position P of the workpiece at the current target grinding time, which is closer to the reference position C, and stores it in the residual grinding burn deepest position storage unit. It is included in the grinding system. [Effects of the Invention]

[0007] According to the above embodiment, the provisional deepest position Pa of the current grinding burn depth on the workpiece, calculated based on the correspondence between the actual depth of cut when the workpiece was ground at the target grinding time, the grinding characteristic quantity extracted from the grinding state quantity, and the grinding burn depth caused on the workpiece by grinding, is compared with the previously updated deepest position P of residual grinding burn. The position closer to the reference position C inside the workpiece is updated as the deepest position P of residual grinding burn for the current target grinding time. Therefore, the deepest position of residual grinding burn on the workpiece can always be grasped in its most up-to-date state. This makes it possible to accurately detect the grinding burn depth remaining on the workpiece.

[0008] As described above, according to the above embodiment, a grinding system can be provided that can accurately detect the depth of grinding burn remaining on the surface of a ground workpiece. [Brief explanation of the drawing]

[0009] [Figure 1] A conceptual diagram showing the configuration of the grinding system in Embodiment 1. [Figure 2] A functional block diagram showing the general configuration of the processing apparatus in Embodiment 1. [Figure 3] A diagram showing the configuration of the measuring device in Embodiment 1. [Figure 4] A diagram showing an example of a correspondence stored in the correspondence storage unit in Embodiment 1. [Figure 5] Flow chart showing the processing by the grinding system in Embodiment 1. [Figure 6] Flow chart showing the grinding process in Embodiment 1. [Figure 7] Graph showing the relationship between the grinding burn depth and the actual depth of cut in Embodiment 1. [Figure 8] Flow chart of the residual grinding burn determination process in Embodiment 1. [Figure 9] In Embodiment 1, (a) Graph explaining the relationship between the current deepest grinding burn position and the residual deepest grinding burn position, (b) Another graph explaining the relationship between the current deepest grinding burn position and the residual deepest grinding burn position. [Figure 10] In Embodiment 1, (a) Graph explaining the relationship between the current deepest grinding burn position and the residual deepest grinding burn position, (b) Another graph explaining the relationship between the current deepest grinding burn position and the residual deepest grinding burn position. [Figure 11] Flow chart of the final residual grinding burn determination process in Embodiment 1. [Figure 12] In Embodiment 1, (a) Graph showing an example of the result of the residual grinding burn determination process, (b) Another graph showing another example of the result of the residual grinding burn determination process. [Figure 13] Functional block diagram showing the general configuration of the processing device in Embodiment 2. [Figure 14] Flow chart of the residual grinding burn determination process in Embodiment 1. [Figure 15] In Embodiment 1, (a) Graph explaining the state before update by the grinding condition update unit, (b) Graph explaining the state after update by the grinding condition update unit.

MODE FOR CARRYING OUT THE INVENTION

[0010] (Embodiment 1) 1. Configuration of the grinding system 1 The grinding system 1 in the present Embodiment 1 will be described with reference to FIG. 1. The grinding system 1 targets a processing device that performs grinding on a workpiece. The grinding system 1 includes a grinding machine 2 as a processing device and a processing unit 3.

[0011] The grinding machine 2 rotates the workpiece W about the center line C, rotates the grinding wheel 16 as a rotating tool, and relatively approaches the grinding wheel 16 in a direction intersecting the axis of the workpiece W with respect to the workpiece W, thereby grinding the outer peripheral surface or the inner peripheral surface of the workpiece W. The grinding machine 2 can be applied to a table traverse type grinding machine, a grinding wheel table traverse type grinding machine, etc. Further, the grinding machine 2 can be applied to a cylindrical grinding machine, a cam grinding machine, etc.

[0012] In the present embodiment, as shown in FIG. 1, the workpiece W is, for example, a member formed in a shaft shape, and the case where the outer peripheral surface of the workpiece W is the machined part is taken as an example. However, the shape of the workpiece W is not limited to a shaft shape, and can be any shape such as a cylindrical shape having an inner peripheral surface. When the workpiece W is cylindrical, the inner peripheral surface of the workpiece W can be taken as the machined part.

[0013] In the present embodiment, the workpiece W is substantially rod-shaped and is supported by workpiece support members at both ends. However, the workpiece W shown in FIG. 1 is an example, and the grinding machine 2 can grind workpieces having various shapes.

[0014] The processing unit 3 includes a processing device 31 that performs processing described later and a control device 32 that controls the grinding machine 2. The processing device 31 has a learning processing device 33 and a determination device 34. As will be described later, the determination device 34 determines whether or not grinding burn remains in the grinding of the workpiece W, and adjusts the grinding conditions for the workpiece W based on the determination result. The control device 32 controls the grinding process by controlling the grinding machine 2.

[0015] The processing unit 31 can function as a simulation device independent of the grinding machine 2 and the control device 32, or as a simulation device that operates in conjunction with the grinding machine 2 and the control device 32. In the former case, the processing unit 31 can determine the optimal grinding conditions without actually grinding the workpiece W. In the latter case, the processing unit 31 can adjust the grinding conditions or operate in a way that affects various controls by processing in parallel with the grinding of the workpiece W by the grinding machine 2. Furthermore, the processing unit 31 can be integrated into the grinding machine 2 and the control device 32.

[0016] 2. Configuration of the grinding machine 2 and control device 32 The configuration of the grinding machine 2 will be described with reference to Figure 1. In this embodiment 1, the grinding machine 2 is an example of a cylindrical grinding machine with a grinding wheel base traverse. However, a table traverse type may also be used for the grinding machine 2. The grinding machine 2 mainly comprises a bed 11, a headstock 12, a tailstock 13, a traverse base 14, a grinding wheel base 15, a grinding wheel 16, a sizing device 17, a grinding wheel adjustment device 18, and a coolant device 19.

[0017] The bed 11 is fixed to the mounting surface. The headstock 12 is located on the upper surface of the bed 11, on the front side in the X-axis direction (lower side in Figure 1) and on one end side in the Z-axis direction (left side in Figure 1). The headstock 12 supports the workpiece W so that it can rotate around the Z-axis with respect to the center line C. The workpiece W is rotated by the drive of a motor 12a provided on the headstock 12. The tailstock 13 is located on the upper surface of the bed 11, opposite the headstock 12 in the Z-axis direction, that is, on the front side in the X-axis direction (lower side in Figure 1) and on the other end side in the Z-axis direction (right side in Figure 1). In other words, the headstock 12 and tailstock 13 rotatably support the workpiece W at both ends.

[0018] The traverse base 14 is mounted on the upper surface of the bed 11 so as to be movable in the Z-axis direction. The traverse base 14 is moved by the drive of a motor 14a mounted on the bed 11. The grinding wheel base 15 is mounted on the upper surface of the traverse base 14 so as to be movable in the X-axis direction. The grinding wheel base 15 is moved by the drive of a motor 15a mounted on the traverse base 14. The grinding wheel 16 is rotatably supported on the grinding wheel base 15. The grinding wheel 16 rotates by the drive of a motor 16a mounted on the grinding wheel base 15. The grinding wheel 16 is constructed by fixing multiple abrasive grains with a bonding agent.

[0019] The sizing device 17 measures the dimensions (diameter) of the workpiece W. The sizing device 17 functions as a detector 20 for obtaining the actual depth of cut in the workpiece W. As shown in Figure 3, the sizing device 17 mainly comprises a device body 171, a pair of contacts 172a and 172b, a pair of fingers 173a and 173b, and a differential transformer 174. The contacts 172a and 172b are provided so as to be able to contact the outer circumferential surface of the workpiece W. Specifically, of the pair of contacts 172a and 172b, one contact 172a contacts the outer circumferential surface of the workpiece W from above, and the other contact 172b contacts the outer circumferential surface of the workpiece W from below. The fingers 173a and 173b hold the contacts 172a and 172b and support the contacts 172a and 172b relative to the device body 171 so as to be able to move relative to them. Specifically, of the pair of fingers 173a and 173b, one finger 173a supports one contact 172a, and the other finger 173b supports the other contact 172b.

[0020] The differential transformer 174 is housed in the main body 171 of the device. The differential transformer 174 detects the displacement of a pair of fingers 173a and 173b that displace in conjunction with the displacement of a pair of contactors 172a and 172b, and outputs an electrical signal corresponding to the displacement of the fingers 173a and 173b to the control device 32. Based on the electrical signal output from the differential transformer 174, the control device 32 detects the position of the fingers 173a and 173b when the pair of contactors 172a and 172b contact the outer surface of the workpiece W, and can obtain the measurement result of the outer diameter of the workpiece W by the sizing device 17 based on the position of the fingers 173a and 173b. The sizing device 17 may also be equipped with other detectors 20, such as an acceleration sensor, a microphone, or a temperature sensor.

[0021] The grinding wheel correction device 18 corrects the shape of the grinding wheel 16. The grinding wheel correction device 18 is a device that performs truing of the grinding wheel 16. In addition to truing, or as an alternative to truing, the grinding wheel correction device 18 may also be a device that performs dressing of the grinding wheel 16. Furthermore, the grinding wheel correction device 18 also has a function to measure the dimensions (diameter) of the grinding wheel 16.

[0022] Here, truing is a reshaping process, which involves shaping the grinding wheel 16 to match the shape of the workpiece W when the grinding wheel 16 is worn down by grinding, and removing runout of the grinding wheel 16 caused by uneven wear. Dressing is a sharpening process, which involves adjusting the amount of abrasive grain protrusion and creating cutting edges for the abrasive grains. Dressing is a process to correct clogged, damaged, or chipped abrasive grains, and is usually performed after truing.

[0023] The coolant system 19 supplies coolant from the coolant nozzle to the grinding point of the workpiece W by the grinding wheel 16. The coolant system 19 cools the recovered coolant to a predetermined temperature and supplies it again to the grinding point. The coolant system 19 allows for adjustment of the coolant flow rate and supply timing. In Figure 1, reference numeral 19 indicates the position of the coolant nozzle. Although not shown, a temperature sensor, such as a detector 20, may also be provided to acquire the temperature of the recovered coolant.

[0024] The control device 32 grinds the workpiece W by controlling the drive of the grinding wheel 16 and coolant device 19 in the grinding machine 2 based on an NC program generated based on operation command data such as the shape of the workpiece W, grinding conditions, the shape of the grinding wheel 16, and coolant flow rate or supply timing information. In particular, the control device 32 grinds the workpiece W until it reaches the finished shape (target shape) based on the grinding conditions created by the grinding condition adjustment unit 350 (described later) and the diameter of the workpiece W measured by the sizing device 17. The control device 32 also corrects the grinding wheel 16 (truing and dressing) by controlling the grinding wheel correction device 18, etc., at the timing when the grinding wheel 16 needs to be corrected.

[0025] 3. Configuration of the learning processing device 33 The learning processing device 33 shown in Figure 2 creates a trained model as a correspondence between feature quantities and grinding burn depth. As shown in Figure 2, the learning processing device 33 comprises a training data acquisition unit 331, a grinding burn depth acquisition unit 332, a feature quantity calculation unit 333, and a model creation unit 334. The training data acquisition unit 331 acquires training data for creating a trained model using grinding state quantities obtained by the detector 20 when the workpiece W is ground. The grinding state quantities include the actual depth of cut in the workpiece W, as well as at least one of the following: the power of the grinding wheel 16, the tangential resistance and normal resistance of the grinding wheel 16 to the workpiece W, the temperature at the processing point, the coolant temperature, and the coolant flow rate, and include various data about grinding in the workpiece W. It is preferable that the grinding state quantities include multiple data from the data listed together with the actual depth of cut.

[0026] In this embodiment 1, the training data acquisition unit 331 acquires training data for workpieces W that have been ground and whose presence or absence of grinding burn residue has been determined. Then, the grinding burn depth acquisition unit 332 acquires the grinding burn depth associated with the training data. In this learning processing device 33, the grinding burn depth can be a value obtained by corroding a workpiece for model creation and performing a destructive test, and measuring it. The feature calculation unit 333 calculates several features related to the grinding burn depth from the training data. These are composed of a predetermined calculation device (not shown).

[0027] Then, the model creation unit 334 creates a trained model based on the feature quantities and the grinding burn depth. The model creation unit 334 is also composed of a predetermined computing device (not shown). The correspondence between the actual cutting depth, the grinding burn depth, and the feature quantities is defined for each feature quantity. For example, the correspondence between the actual cutting depth and the grinding burn depth for a given feature quantity can be expressed as a nonlinear regression equation, as shown in Figure 4. This correspondence is not limited to a two-dimensional graph; it may also be multi-dimensional, or it may be expressed as a relationship equation between the actual cutting depth, the feature quantity, and the grinding burn depth. The trained model created by the model creation unit 334 is stored in the correspondence storage unit 343, which will be described later.

[0028] The form of the trained model created by the model creation unit 334 is not limited and may be created by machine learning based on training data. In this embodiment, the trained model may be a neural network.

[0029] 4. Configuration of the determination device 34 As shown in Figure 2, the determination device 34 includes an actual cutting depth acquisition unit 341, a grinding state amount acquisition unit 342, a correspondence relationship storage unit 343, a current grinding burn estimation unit 344, a provisional grinding burn deepest position calculation unit 345, a residual grinding burn deepest position storage unit 346, a residual grinding burn deepest position update unit 347, a final residual burn determination unit 348, a determination result display unit 349, and a grinding condition adjustment unit 350.

[0030] The actual cutting depth acquisition unit 341 acquires the actual cutting depth based on the value acquired by the detector 20. In this embodiment 1, the dimension of the outer surface of the workpiece W is detected by the measuring device 17, which acts as the detector 20, and the amount of change before and after one rotation is acquired as the actual cutting depth.

[0031] The grinding state quantity acquisition unit 342 acquires the above-mentioned grinding state quantity based on various data detected by the detector 20 when grinding the workpiece W that is the target of grinding. The correspondence relationship storage unit 343 stores the above-mentioned trained model as the correspondence between the actual cutting depth, the grinding state quantity (feature quantity), and the grinding burn depth.

[0032] The current grinding burn estimation unit 344 estimates the grinding burn depth A that occurs on the workpiece W at each grinding time due to grinding under the grinding conditions at each grinding time, based on the actual depth of cut acquired by the actual depth of cut acquisition unit 341, the grinding state amount acquired by the grinding state amount acquisition unit 342, and the correspondence stored in the correspondence relationship storage unit 343.

[0033] The provisional grinding burn deepest position calculation unit 345 calculates the provisional deepest position Pa, which is the provisional value of the deepest grinding burn occurring on the workpiece W at the target grinding time. This position is moved from the surface position D of the workpiece W at the target grinding time to a position towards the reference position C set inside the workpiece W by the amount of the current grinding burn depth A estimated by the current grinding burn depth estimation unit 344 at the target grinding time. The inside of the workpiece W is the area near the center line C of the workpiece W when the outer surface of the workpiece W is the workpiece, and the area away from the center line C of the workpiece W when the inner surface of the workpiece W is the grinding area. In this embodiment 1, the reference position C coincides with the position of the center line C of the workpiece W.

[0034] The deepest residual grinding burn position storage unit 346 stores the deepest residual grinding burn position P, which is the deepest residual grinding burn position remaining on the workpiece W. As will be described later, the deepest residual grinding burn position P is stored in the deepest residual grinding burn position storage unit 346 as the latest deepest residual grinding burn position P each time it is updated.

[0035] The residual grinding burn deepest position update unit 347 compares the provisional deepest position Pa of grinding burn on the workpiece W, calculated by the provisional deepest position calculation unit 345 at the target grinding time, with the residual grinding burn deepest position P of the same workpiece W at the previous target grinding time, which is stored in the residual grinding burn deepest position storage unit 346. In this embodiment 1, since the workpiece W is cylindrical and its outer surface is the workpiece, the provisional deepest position Pa and the residual grinding burn deepest position P at the previous target grinding time are located at the same position in the circumferential direction of the workpiece W. In the case of the first time (i.e., the first rotation of the workpiece W), the residual grinding burn deepest position P at the previous target grinding time can be treated as the surface position D of the workpiece W.

[0036] Furthermore, the residual grinding burn deepest position updating unit 347 updates the position closest to the reference position C as the residual grinding burn deepest position P for the workpiece W at the current grinding time, and stores it in the residual grinding burn deepest position storage unit 346 as described above. The residual grinding burn deepest position updating unit 347 continuously performs the comparison between the provisional deepest position Pa and the residual grinding burn deepest position P, the updating of the residual grinding burn deepest position P, and storage while grinding the workpiece W.

[0037] In this embodiment 1, the workpiece W is configured to rotate relative to the grinding wheel 16, which is a grinding tool that grinds the workpiece, thereby grinding the same workpiece multiple times. In the residual grinding burn deepest position updating section 347, the previous target grinding time is the time one rotation prior to the current target grinding time.

[0038] The final residual grinding burn determination unit 348 determines that grinding burn remains on the workpiece if the deepest residual grinding burn position P, updated by the deepest residual grinding burn position update unit 347 at the end of grinding, is located on the side of the reference position C that is closer to the workpiece surface position D. On the other hand, if the deepest residual grinding burn position P, updated by the deepest residual grinding burn position update unit at the end of grinding, coincides with the surface position D of the workpiece W, it determines that no grinding burn remains on the workpiece W.

[0039] The judgment result display unit 349 displays the judgment result from the final residual grinding burn judgment unit 348. The format in which the judgment result is displayed on the judgment result display unit 349 is not limited. The grinding condition adjustment unit 350 creates the above-mentioned grinding conditions based on the judgment result from the final residual grinding burn judgment unit 348 and transmits them to the control device 32.

[0040] For example, if the final residual grinding burn determination unit 348 determines that grinding burns remain on the workpiece W after grinding, the grinding condition adjustment unit 350 can adjust the grinding conditions in the next grinding cycle to reduce the grinding efficiency in the rough grinding step. The grinding efficiency can be changed by changing the depth of cut and cutting speed of the grinding wheel 16, or by changing the dress lead of the grinding wheel 16.

[0041] On the other hand, if the determination result by the final residual grinding burn determination unit 348 indicates that no grinding burn remains on the workpiece W after grinding, the grinding condition adjustment unit 350 can increase the grinding efficiency in the next rough grinding step or adjust the grinding conditions to maintain the grinding efficiency, within the margin range derived from the relationship between the grinding burn depth and the workpiece radius after grinding.

[0042] 5. Processing using grinding system 1 As shown in Figure 5, the grinding system 1 performs the grinding process S1 and the residual grinding burn calculation process S2 in parallel, followed by the final residual grinding burn determination process S3. 5-1. Explanation of Grinding Process First, let's explain the grinding process S1. As shown in Figure 6, the grinding process S1 includes a rough grinding step S11, a fine grinding step S12, a micro grinding step S13, and a spark-out step S14.

[0043] In the rough grinding process S11, the control device 32 rotates the grinding wheel 16 at a predetermined speed based on operation command data such as the shape of the workpiece W, grinding conditions, the shape of the grinding wheel 16, and the flow rate or supply timing information of the coolant, and grinds the workpiece W with a first depth of cut. In the fine grinding process S12, the control device 32 grinds the workpiece W with a second depth of cut lower than the first depth of cut. In the fine grinding process S13, the control device 32 grinds the workpiece W with a third depth of cut lower than the second depth of cut. In the spark-out process S14, the workpiece W is rotated at a preset rotational speed to grind away the remaining material from the fine grinding process S13, making the cross-sectional shape a perfect circle. The depth of cut can be adjusted by controlling the cutting position of the grinding wheel 16 with the control device 32.

[0044] In this embodiment 1, the first to third depths of cut in each process S11 to S13 are set as displacement amounts shown by black circles in Figure 7. In the spark-out process S14, the actual depth of cut is substantially zero. The relationship between the depth of cut in each process S11 to S14 and the grinding burn depth that occurs when grinding the workpiece W with each depth of cut is defined as shown in Figure 7.

[0045] As shown in Figure 7, grinding burn caused by grinding the workpiece W mainly occurs in the rough grinding process S11. In the fine grinding process S12, there is a slight possibility of new grinding burn occurring immediately after switching from the rough grinding process S11, but there is almost no new grinding burn occurring in the fine grinding process S12, the micro grinding process S13, and the spark-out process S14 thereafter. When the spark-out process S14 is completed, the grinding process S1 is terminated. The end time of the grinding process S1 is defined as the grinding end time T5.

[0046] 5-2. Explanation of the process for calculating residual grinding burn depth The residual grinding burn calculation process S2 shown in Figure 8 will be explained below. As shown in Figure 8, the grinding burn determination process first involves, in step S21, obtaining the actual cutting depth in the workpiece W from the workpiece W and the grinding machine 2 based on the detection values ​​of the detector 20 using the actual cutting depth acquisition unit 341, and obtaining grinding state quantities related to the grinding of the workpiece W using the grinding state quantity acquisition unit 342.

[0047] Next, in step S22, the current grinding burn depth estimation unit 344 estimates the current grinding burn depth A. The current grinding burn depth A is estimated as the grinding burn depth that occurs on the workpiece W at each grinding time due to grinding under the grinding conditions at each grinding time, based on the actual depth of cut and grinding state acquired in step S21 and the correspondence stored in the correspondence storage unit 343. For example, as shown in Figure 7, the current grinding burn depth A that occurs at the target grinding time T1 in the rough grinding process S11 can be shown as A1.

[0048] Then, in step S23, the provisional grinding burn deepest position calculation unit 345 calculates the provisional grinding burn deepest position Pa. In the example shown in Figure 9(a), at the target grinding time T1 in the rough grinding process S11, the provisional grinding burn deepest position Pa is calculated as Pa1, which is the position moved from the surface position D of the workpiece W at the target grinding time toward the reference position C by the amount of the current grinding burn depth A1. In Figure 9(a), the trajectory of Pa at each target grinding time is shown as a dashed line as the Pa transition. Similarly, the trajectory of P at each target grinding time is shown as the P transition, and the trajectory of D is shown as the D transition, both as solid lines.

[0049] Subsequently, in step S24, the residual grinding burn deepest position update unit 347 compares the provisional grinding burn deepest position Pa with the previous (time T0) residual grinding burn deepest position P stored in the residual grinding burn deepest position storage unit 346 to determine whether the provisional grinding burn deepest position Pa is closer to the reference position C than the previous residual grinding burn deepest position P.

[0050] In step S24, in the example shown in Figure 9(a), the provisional deepest grinding burn position Pa at the target grinding time T1 is closer to the reference position C than the deepest residual grinding burn position P at the previous time (one rotation earlier) T0, so the process proceeds to Yes in step S24. Then, in step S25, the deepest residual grinding burn position update unit 347 updates the provisional deepest grinding burn position Pa at the target grinding time T1 as the deepest residual grinding burn position P for the current grinding time T1, and the updated deepest residual grinding burn position P is stored in the deepest residual grinding burn position storage unit 346.

[0051] Subsequently, in step S26, the control device 32 determines whether or not the grinding completion time has arrived. If it is determined that the grinding completion time has not arrived, the process proceeds to step S26 No. and returns to step S21 again.

[0052] Then, for example, steps S21 and S22 are performed similarly for the target grinding time T2, which is one rotation after time T1. Note that at the target grinding time T2, the grinding process is the fine grinding process S12. The current grinding burn depth A that occurs at the target grinding time T2 can be shown as A2, as shown in Figure 7.

[0053] Then, proceeding to step S23, as in the case described above, the provisional deepest grinding burn position Pa at the target grinding time T2 is calculated as Pa2, which is the position moved from the surface position D of the workpiece W at the target grinding time toward the reference position C by the amount of the current grinding burn depth A2, as shown in Figure 9(b).

[0054] Furthermore, in step S24, similar to the case described above, the provisional deepest grinding burn position Pa at the target grinding time T2 is compared with the deepest residual grinding burn position P updated at the previous time (one rotation prior) T1. At the target grinding time T2, as shown in Figure 9(b), the provisional deepest grinding burn position Pa is not closer to the reference position C than the deepest residual grinding burn position P at the previous time (one rotation prior) T1, so the process proceeds to step No. in step S24. Then, in step S27, the deepest residual grinding burn position update unit 347 does not update the deepest residual grinding burn position P at the target grinding time T2, but instead stores the deepest residual grinding burn position P from the previous time T1 as the deepest residual grinding burn position P for the current time (target grinding time T2) in the deepest residual grinding burn position storage unit 346. After that, the process proceeds to step S26 as described above.

[0055] As shown in Figure 7, at time T3, which is in the middle of the fine grinding process S12, the current grinding burn depth A, A3, is 0, and thereafter the current grinding burn depth A is maintained at 0. Therefore, as shown in Figure 10(a), after the current grinding burn depth A becomes 0 in the middle of the fine grinding process S12, the deepest residual grinding burn position P is not updated, and the deepest residual grinding burn position P from the previous time (one rotation ago) is maintained.

[0056] Furthermore, as shown in Figure 10(b), if, at grinding time T4, the surface position D of the workpiece W is located closer to the reference position C than the deepest residual grinding burn position P, the provisional deepest grinding burn position Pa is calculated as the position corresponding to the surface position D of the workpiece W, and this provisional deepest grinding burn position Pa is updated as the deepest residual grinding burn position P.

[0057] On the other hand, if it is determined in step S26 that the grinding completion time T5 has arrived, the residual grinding burn calculation process S2 is terminated.

[0058] 5-3. Explanation of the final residual grinding burn determination process S20 Next, the final residual grinding burn determination process S3 will be described. As shown in Figure 11, in the final residual grinding burn determination process S3, in step S31, the final residual grinding burn determination unit 348 determines whether the deepest residual grinding burn position P is located on the side of the reference position C relative to the workpiece surface position D.

[0059] For example, in the example shown in Figure 12(b), the deepest residual grinding burn position P is located on the reference position C side of the workpiece surface position D, so the process proceeds to Yes in step S31, and in step S32, the final residual grinding burn determination unit 348 determines that there is residual grinding burn on the workpiece W. The depth Px of the residual grinding burn on the workpiece W is then expressed as the distance Px from the surface position D of the workpiece W to the deepest residual grinding burn position P at grinding completion time T5.

[0060] Subsequently, the process proceeds to step S33, where the determination result display unit 349 displays a determination result indicating the presence of residual grinding burn. Then, in step S34, the grinding condition adjustment unit 350 adjusts the grinding conditions according to the determination result. In step S34, the grinding condition adjustment unit 350 adjusts the grinding conditions to reduce the grinding efficiency in the rough grinding process S11. In this embodiment 1, the grinding efficiency is reduced by decreasing the cutting speed of the grinding wheel 16 in the rough grinding process S11. Then, the final residual grinding burn determination process S3 is completed.

[0061] On the other hand, in the example shown in Figure 12(a), the deepest position P of residual grinding burn is not located on the reference position C side of the workpiece surface position D, so the process proceeds to step S31 No., and in step S35, the final residual grinding burn determination unit 348 determines that there is no residual grinding burn on the workpiece W. Then, the process proceeds to step S36, and the determination result display unit 349 displays the determination result that there is no residual grinding burn.

[0062] Subsequently, in step S37, the grinding condition adjustment unit 350 calculates the margin M. As shown in Figure 12(a), the margin M is expressed as the distance from the surface position D5 of the workpiece W to the maximum residual grinding burn depth position Py, which is the deepest residual grinding burn depth position P in the grinding processes S11 to S14 that is closest to the reference position C, at the grinding end time T5 of the spark-out process S14. Then, in step S38, the grinding condition adjustment unit 350 increases the grinding efficiency in the rough grinding process S11 so that the margin M is greater than or equal to zero and small, and terminates the final residual grinding burn determination process S20. This makes it possible to increase the grinding efficiency within a range where no grinding burn remains, thus shortening the grinding cycle.

[0063] 6. Effects The effects and advantages of the grinding system 1 in this embodiment 1 are described below. According to the grinding system 1 in this embodiment 1, the provisional deepest position Pa of the current grinding burn depth in the workpiece W, calculated based on the correspondence between the actual depth of cut when the workpiece W is ground at the target grinding time, the grinding characteristic quantity extracted from the grinding state quantity, and the grinding burn depth generated in the workpiece W by grinding, is compared with the previously updated deepest position P of residual grinding burn. The position closer to the reference position C inside the workpiece is updated as the deepest position P of residual grinding burn for the current target grinding time. Therefore, the deepest position P of residual grinding burn remaining in the workpiece W can always be grasped in its most up-to-date state. This makes it possible to accurately detect the grinding burn depth remaining in the workpiece W.

[0064] Furthermore, in this embodiment 1, the workpiece W is configured to rotate relative to the grinding wheel 16, which acts as a grinding tool for grinding the workpiece, thereby grinding the same workpiece multiple times. In the residual grinding burn deepest position update unit 347, the previous target grinding time (e.g., T0) is the time one rotation prior to the current target grinding time (e.g., T1) of the workpiece W. This allows for a reliable comparison of the current provisional deepest grinding burn depth Pa with the previously updated deepest residual grinding burn depth P at the same location on the workpiece, thereby enabling more accurate detection of the grinding burn depth.

[0065] Furthermore, in this embodiment 1, if the deepest residual grinding burn position P, updated by the deepest residual grinding burn position update unit 347 at the end of grinding T5, is located on the side of the reference position C relative to the surface position D of the workpiece, it is determined that grinding burn remains on the workpiece W. Otherwise, it is determined that grinding burn does not remain on the workpiece W. This makes it easy to determine whether or not grinding burn remains on the workpiece W.

[0066] Furthermore, this embodiment 1 includes a determination result display unit 349 that displays the determination result of the final residual grinding burn determination unit 348. This makes it easy to determine whether or not grinding burns remain on the workpiece W.

[0067] Furthermore, this embodiment 1 includes a grinding condition adjustment unit that adjusts the grinding conditions of the workpiece W based on the determination result of the final residual grinding burn determination unit 348. This makes it possible to optimize the grinding conditions of the workpiece W.

[0068] Furthermore, in this embodiment 1, the grinding condition adjustment unit 350 adjusts the grinding conditions to reduce the grinding efficiency for the workpiece W if the determination result of the final residual grinding burn determination unit 348 indicates that grinding burn remains on the workpiece W. This reduces the depth of grinding burn formed on the workpiece W during grinding, thus preventing grinding burn from remaining on the workpiece W after grinding is completed.

[0069] In this embodiment 1, even after the surface position D of the workpiece W was located closer to the reference position C than the deepest residual grinding burn position P, the deepest grinding burn position Pa was continued to be updated as the deepest residual grinding burn position P. However, instead, the updating of the deepest residual grinding burn position P may be stopped when the surface position D of the workpiece W coincides with the maximum deepest residual grinding burn position Pmax, which is the closest to the reference position C among the deepest residual grinding burn positions P.

[0070] As described above, according to the above embodiment, a grinding system can be provided that can accurately detect the depth of grinding burn remaining on the surface of a ground workpiece.

[0071] (Embodiment 2) In this second embodiment, instead of the final residual grinding burn determination unit 348 and grinding condition adjustment unit 350 of the first embodiment, there is an intermediate determination unit 360 and a grinding condition update unit 361, as shown in Figure 13.

[0072] The intermediate determination unit 360 determines whether the deepest residual burn position P, updated by the deepest residual burn position update unit 347 at each grinding time during grinding, is located on the side of the reference position C that is closer to the predetermined determination position X. Then, the grinding condition update unit 361 updates the grinding conditions for grinding after the determination made by the intermediate determination unit 360, based on the determination result of the intermediate determination unit 360.

[0073] In Embodiment 2, after step S25 and step S27 shown in Figure 8, the process proceeds to step S40 shown in Figure 14. In step S40, the intermediate determination unit 360 determines whether the deepest residual burn position P is closer to the reference position C than to the reference position X before the end of the rough grinding process S11. If it is determined that the deepest residual burn position P is closer to the reference position C than to the determination position X before the end of the rough grinding process S11, the process proceeds to Yes in step S40, and in step S41, the grinding condition update unit 361 updates the grinding conditions in the rough grinding process S11 to reduce the grinding efficiency.

[0074] On the other hand, in step S40, if the intermediate determination unit 360 determines that the deepest residual burn position P is not closer to the reference position C than the determination position X before the end of the rough grinding process S11, the process proceeds to step S40 No., and in step S42, the grinding efficiency in the rough grinding process S11 is maintained and the grinding condition update unit 361 does not perform an update. After steps S41 and S42, the process returns to step S21 in Figure 8 in Embodiment 1, and after steps S25 and S27, the process proceeds to step S40 shown in Figure 14 as described above.

[0075] In Embodiment 2, as shown in Figure 15(a), if the deepest residual burn position P at the target grinding time T6 in the rough grinding process S11 is closer to the reference position C than to the determination position X, then excessive grinding burn occurs on the workpiece W, and residual grinding burn is expected to occur at the end of the spark-out process S14, as shown by the dotted line. Therefore, the grinding conditions can be updated in the rough grinding process S11 after the target grinding time T6 to reduce the grinding efficiency and suppress subsequent grinding burn, so that, as shown in Figure 15(b), no grinding burn is expected to remain at the end of the spark-out process S14. As a result, it is possible to further prevent grinding burn from remaining on the workpiece W after grinding.

[0076] In Embodiment 2, the grinding conditions were updated to reduce the grinding efficiency in the rough grinding step S11. However, instead, the grinding conditions may be updated to reduce the material removal in the rough grinding step S11 and increase the material removal in the fine grinding step S12.

[0077] Furthermore, in this second embodiment, instead of the final residual grinding burn determination unit 348 and grinding condition adjustment unit 350 of the first embodiment, an intermediate determination unit 360 and a grinding condition update unit 361 are provided as shown in Figure 13. However, it is also possible to have a configuration in which the intermediate determination unit 360 and grinding condition update unit 361 of the second embodiment are provided along with the final residual grinding burn determination unit 348 and grinding condition adjustment unit 350 of the first embodiment.

[0078] The present invention is not limited to the embodiments described above, and can be applied to various embodiments without departing from its spirit. [Explanation of Symbols]

[0079] 1. Grinding System 2. Grinding machine 31 Processing Unit 32 Control device 33 Learning Processing Device 34 Judgment device 341 Actual cutting depth acquisition unit 342 Grinding state quantity acquisition unit 343 Correspondence Relationship Memory Unit 344 Current grinding burn depth estimation section 345 Provisional calculation unit for the deepest point of grinding burn 346 Storage section for the deepest position of residual grinding burn 347 Deepest point of residual grinding burn - updated section 348 Final residual grinding burn determination section 349 Judgment result display section 350 Grinding condition adjustment unit 360 Midway judgment section 361 Grinding Condition Update Unit

Claims

1. A grinding system that processes the surface of a workpiece to its final target shape by grinding it multiple times, The actual depth of cut when grinding the above workpiece is obtained by acquiring the amount of change in the dimensions of the outer surface of the workpiece when the workpiece is ground once, A grinding state quantity acquisition unit acquires at least one of the following grinding state quantities related to the grinding of the workpiece: the power of the tool for grinding the surface of the workpiece, the tangential and normal resistance of the tool to the workpiece, the temperature of the machining point on the workpiece, the temperature of the coolant supplied to the machining point, and the flow rate of the coolant. A correspondence relationship storage unit pre-stores the correspondence between the actual depth of cut when the above workpiece is ground, the grinding characteristic quantity extracted from the grinding state quantity when the above workpiece is ground, and the grinding burn depth that occurs on the workpiece due to grinding at the grinding time from which the grinding characteristic quantity was extracted. A current grinding burn depth estimation unit estimates the grinding burn depth that occurs on the workpiece at each grinding time due to grinding under the grinding conditions at each grinding time, based on the actual depth of cut acquired by the actual depth of cut acquisition unit, the grinding state amount acquired by the grinding state amount acquisition unit, and the correspondence stored in the correspondence relationship storage unit, as the current grinding burn depth A. A provisional grinding burn depth calculation unit calculates a provisional grinding burn depth Pa, which is a provisional value of the deepest grinding burn position occurring on the workpiece at the target grinding time, by moving from the surface position D of the workpiece at the target grinding time by the amount of the current grinding burn depth A estimated by the current grinding burn depth estimation unit towards the reference position C set inside the workpiece at the target grinding time. A storage unit for the deepest residual grinding burn position P, which is the deepest position of grinding burn remaining on the workpiece, A residual grinding burn deepest position update unit compares the provisional grinding burn deepest position Pa of the grinding burn in the workpiece, calculated by the provisional grinding burn deepest position calculation unit at the target grinding time, with the residual grinding burn deepest position P of the same workpiece at the previous target grinding time, which is stored in the residual grinding burn deepest position storage unit, and updates the residual grinding burn deepest position P of the workpiece at the current target grinding time, whichever is closer to the reference position C, and stores it in the residual grinding burn deepest position storage unit. A grinding system including the following:

2. The above workpiece is configured to rotate relative to the grinding tool that grinds the workpiece, thereby grinding the same workpiece multiple times. The grinding system according to claim 1, wherein in the section where the deepest position of residual grinding burn is updated, the previous target grinding time is the time one rotation prior to the current target grinding time of the workpiece.

3. A grinding system according to claim 1 or 2, comprising a final residual grinding burn determination unit, which determines that grinding burns remain on the workpiece if the deepest residual grinding burn position P, updated by the deepest residual grinding burn position updating unit at the end of grinding, is located on the side of the reference position C that is greater than the surface position D of the workpiece, and determines that grinding burns do not remain on the workpiece if the deepest residual grinding burn position P, updated by the deepest residual grinding burn position updating unit at the end of grinding, coincides with the surface position D of the workpiece.

4. The grinding system according to claim 3, further comprising a determination result display unit that displays the determination result of the final residual grinding burn determination unit described above.

5. The grinding system according to claim 3 or 4, further comprising a grinding condition adjustment unit that adjusts the grinding conditions of the workpiece based on the determination result of the final residual grinding burn determination unit described above.

6. The grinding system according to claim 5, wherein the grinding condition adjustment unit adjusts the grinding conditions to reduce the grinding efficiency for the workpiece when the determination result of the final residual grinding burn determination unit indicates that grinding burn remains on the workpiece.

7. The system includes an intermediate determination unit that determines whether the deepest residual grinding burn position P, updated by the deepest residual grinding burn position update unit at each grinding time during grinding, is located on the side of the reference position C that is closer to a predetermined determination position X. A grinding system according to any one of claims 1 to 6, further comprising a grinding condition update unit that updates the grinding conditions for the grinding process after the determination by the intermediate determination unit based on the determination result of the intermediate determination unit.

8. The grinding of the above workpiece is configured to include a first grinding step in which the workpiece is ground under first grinding conditions, followed by a second grinding step in which the workpiece is ground under second grinding conditions that have a lower grinding efficiency than the first grinding conditions. The grinding system according to claim 7, wherein the grinding condition updating unit updates the grinding conditions to reduce the grinding efficiency in at least the first grinding step if the intermediate determination unit determines, before the first grinding step is completed, that the deepest residual grinding burn position P is located on the side of the reference position C that is further than a predetermined determination position.

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