JP5821616B2 - Grinding abnormality monitoring method and grinding abnormality monitoring apparatus - Google Patents

Description

  The present invention relates to a method for monitoring a grinding abnormality in grinding a workpiece and a device for monitoring a grinding abnormality.

  For example, in Japanese Patent Laid-Open No. 4-176541 (Patent Document 1), as a method of determining an abnormality in grinding a workpiece, an abnormality is described when the driving power of the grinding wheel driving motor of the grinding wheel exceeds a predetermined threshold. It is described that it is judged. That is, when the grinding load calculated from the driving power of the grinding wheel driving motor becomes larger than a predetermined threshold value, a work-affected layer is generated on the workpiece, so that it is determined to be abnormal.

JP-A-4-176541

  In general, the grinding cycle is performed in the order of the air laboratory, the rough grinding, the finishing, and the spark-out process. In addition, RAR has a process that is divided into the first RAR and the second RAR. In the first rough process, the black skin is mainly removed. Here, the black skin generally refers to an oxide film on the surface of a workpiece after a hot rolling or cold rolling process, but in the following description, not only hot rolling and cold rolling but also quenching is performed. It shall include a coating on the surface of the workpiece after a process such as heat treatment, cutting, casting, forging or the like. And a 1st rough process means the process of grinding the film on the surface of a workpiece with a grinding wheel. In the first roughing process, which is the initial machining process between the workpiece and the grinding wheel, the relative movement between the workpiece and the grinding wheel is maintained at a constant speed until the workpiece and the grinding wheel come into contact. In addition, the cutting amount of the workpiece by the grinding wheel is ground at a constant level. Therefore, in the first roughing process, as the grinding proceeds, the contact area per unit time between the workpiece and the grinding wheel increases, so that the grinding load increases and a work-affected layer may occur in the workpiece. Also, since the shape accuracy of the workpiece before grinding varies, the contact area between the workpiece and the grinding wheel greatly fluctuates in the first roughing process, and the grinding load also fluctuates greatly, resulting in a work-affected layer on the workpiece. May occur.

  Even if a work-affected layer is generated on the workpiece in the first roughing process, it may be determined to be normal if the work-affected layer can be removed by the subsequent second roughing process or finishing process. However, in the conventional grinding abnormality determination method, the threshold value is set so that a work-affected layer does not occur in the workpiece. Therefore, even if the final processed product is normal, it is determined to be abnormal once the threshold value is exceeded once in the first rough process.

  The present invention has been made in view of such circumstances, and when a work-affected layer is generated in a work piece in an initial machining process between the work piece and a grinding wheel, the accuracy of determining grinding abnormality is improved. An object of the present invention is to provide a grinding abnormality monitoring method and a grinding abnormality monitoring apparatus capable of performing the above.

(Claim 1) The grinding abnormality monitoring method of the present invention is the grinding abnormality monitoring method for monitoring a grinding abnormality by using a grinder for grinding the workpiece by relatively moving a workpiece and a grinding wheel. Grinding remaining machining allowance detecting step for detecting a remaining grinding allowance when grinding the workpiece in the initial machining process of the contact between the workpiece and the grinding wheel, and grinding the workpiece in the initial machining process Corresponding to the detected grinding load based on the relationship between the grinding load detection step for detecting the grinding load and the relationship in which the thickness of the work-affected layer of the workpiece changes when the grinding load changes when the workpiece is ground. The thickness of the work-affected layer is obtained, the obtained thickness of the work-affected layer is compared with the detected grinding remaining allowance, and the work-affected layer generated on the workpiece is removed by grinding after the occurrence. This And a grinding abnormality determination step of determining a grinding abnormality on whether is possible.

  (Claim 2) The remaining grinding allowance detection step detects the remaining grinding allowance at the end of the initial contact machining step, and the grinding load detection step detects the grinding at the end of the initial contact machining step. The load is detected, and the grinding abnormality determination step determines that the grinding abnormality is detected when the thickness of the work-affected layer corresponding to the detected grinding load exceeds the detected grinding remaining allowance. Good.

(Claim 3) The grinding abnormality monitoring method of the present invention is the grinding abnormality monitoring method for monitoring a grinding abnormality using a grinding machine for grinding the workpiece by relatively moving the workpiece and the grinding wheel. Grinding remaining machining allowance detecting step for detecting a remaining grinding allowance when grinding the workpiece in the initial machining process of the contact between the workpiece and the grinding wheel, and grinding the workpiece in the initial machining process Grinding load detection step for detecting a grinding load, a relationship in which the thickness of the work-affected layer of the workpiece changes when the grinding load changes when the workpiece is ground, and a remaining grinding allowance when grinding the workpiece based on the a threshold setting step of setting in accordance with the grinding remaining allowance, detecting the damaged layer generated in the workpiece as a threshold grinding load that can be removed by grinding after the occurrence And a determining grinding abnormality determination process that the grinding abnormality when the grinding load in the grinding remainder allowance exceeds the threshold value corresponding to the grinding remaining allowance was detected.

  (Claim 4) The grinding abnormality monitoring method includes a control step of changing a grinding condition of the grinding wheel, and the control step is such that the detected grinding load does not exceed the threshold and approaches the threshold. In addition, the grinding conditions of the grinding wheel may be changed.

  (Claim 5) The processing step in the initial stage of contact is a step in which relative movement between the workpiece and the grinding wheel is performed at a constant speed and a cutting amount of the workpiece by the grinding wheel is constant. May be.

(Grinding abnormality monitoring device)
(Claim 6) The grinding abnormality monitoring device of the present invention is the grinding abnormality monitoring device for monitoring a grinding abnormality by using a grinder for grinding the workpiece by relatively moving the workpiece and the grinding wheel. Grinding remaining machining allowance detecting means for detecting a remaining grinding allowance when grinding the workpiece in the machining process in the initial contact stage between the workpiece and the grinding wheel, and grinding the workpiece in the machining process in the initial contact stage. Corresponding to the detected grinding load based on the relationship between the grinding load detecting means for detecting the grinding load and the change in the thickness of the work-affected layer of the workpiece when the grinding load changes when the workpiece is ground. The thickness of the work-affected layer is obtained, the obtained thickness of the work-affected layer is compared with the detected grinding remaining allowance, and the work-affected layer generated on the workpiece is removed by grinding after the occurrence. This And a grinding abnormality determining means for determining a grinding abnormality on whether is possible.
(Claim 7) The grinding abnormality monitoring device of the present invention is the grinding abnormality monitoring device for monitoring a grinding abnormality by using a grinder for grinding the workpiece by relatively moving the workpiece and the grinding wheel. Grinding remaining machining allowance detecting means for detecting a remaining grinding allowance when grinding the workpiece in the machining process in the initial contact stage between the workpiece and the grinding wheel, and grinding the workpiece in the machining process in the initial contact stage. Grinding load detecting means for detecting a grinding load, a relationship in which the thickness of a work-affected layer of the workpiece changes when the grinding load changes when the workpiece is ground, and a remaining grinding allowance when grinding the workpiece And a threshold value setting means for setting the grinding load that can be removed by grinding after the occurrence of the work-affected layer generated on the workpiece as a threshold value according to the remaining grinding allowance. And a determining grinding abnormality determining means that the grinding abnormality when the grinding load in the grinding remainder allowance exceeds the threshold value corresponding to the grinding remaining allowance was detected.

  (Claim 1) When a work-affected layer is generated in a work piece in an initial machining step (hereinafter referred to as "first roughing process") between the work and the grinding wheel, the work-affected layer is removed by subsequent grinding. However, if it is impossible to remove the work-affected layer by subsequent grinding, it may be determined to be abnormal. Therefore, as in the grinding abnormality monitoring method of the present invention, the grinding detected in the first roughing process is based on the relationship in which the thickness of the work-affected layer of the workpiece changes when the grinding load changes when the workpiece is ground. The thickness of the work-affected layer corresponding to the load is obtained. Then, the obtained thickness of the work-affected layer is compared with the grinding remaining allowance detected in the first roughing process. Thereby, even when a work-affected layer occurs in the workpiece in the first roughing process, it is possible to improve the accuracy of determining grinding abnormality and reduce the grinding failure rate of the workpiece.

  (Claim 2) The remaining grinding allowance at the end of the first roughing process is detected, and the grinding load at the end of the first roughing process is detected. Thereby, since grinding | polishing abnormality can be determined before performing the rough process after a 1st rough process, production efficiency can be improved.

  (Claim 3) Based on the relationship in which the thickness of the work-affected layer of the workpiece changes when the grinding load changes when the workpiece is ground, the threshold for the grinding load relative to the remaining grinding allowance during the first roughing process is set. Set. Thereby, since grinding abnormality can be determined in the first roughing process, the production efficiency can be further improved.

  (Claim 4) When judging the grinding abnormality, if the grinding load does not exceed the threshold value, it is judged as normal. Therefore, even if the grinding condition is changed so that the grinding load does not exceed the threshold value and approaches the threshold value, it can be determined as normal. Therefore, by setting a condition change target value that does not exceed the threshold value and is close to the threshold value, and when the condition change target value is exceeded, the grinding condition is changed so as to fall below the condition change target value, so that the grinding time, that is, Grinding cycle time can be shortened.

  (Claim 5) In the process in which the relative movement between the workpiece and the grinding wheel is performed at a constant speed and the cutting depth of the workpiece by the grinding wheel is constant, the grinding load varies greatly. Therefore, by applying the grinding abnormality monitoring method of the present invention to the process, it is possible to improve the determination accuracy of grinding abnormality.

(Claim 6) (Claim 7) According to the grinding abnormality monitoring apparatus of the present invention, the same effects as those in the above-described grinding abnormality monitoring method can be obtained. Further, other characteristic portions in the grinding abnormality monitoring method can be similarly applied to the grinding abnormality monitoring apparatus of the present invention. And the same effect is produced.

It is a top view of a grinding machine. 1 is a functional block diagram of a grinding abnormality monitoring device. 1st embodiment: It is a flowchart of an abnormality monitoring program. It is a figure which shows the table data of the relationship between a grinding load and a process-affected layer thickness. It is a figure which shows the grinding load with respect to a general grinding remainder machining allowance. The history display state of the screen of the display device is shown. 2nd embodiment: It is a functional block diagram of the grinding abnormality monitoring apparatus. 2nd embodiment: It is a flowchart of an abnormality monitoring program. 2nd embodiment: It is a figure which shows the threshold value of grinding load with respect to grinding remaining allowance, and the target value for condition changes.

(1. Machine configuration of grinding machine)
As an example of the grinding machine 1, a headstock traverse type internal grinding machine will be described as an example and described with reference to FIG. 1. A case where the workpiece W to be ground by the grinding machine 1 is used as an outer ring of a bearing and the inner peripheral raceway surface of the outer ring of the bearing is ground using the grinding machine 1 will be described as an example. Here, a case where a plurality of workpieces W of the same type are ground, that is, a case where a workpiece W as a mass-produced product is manufactured will be described.

  As shown in FIG. 1, the grinding machine 1 includes a bed 10, a table 20, a headstock 30, a grindstone support device 40, a proximity switch 50, a contact detection sensor 80, and a grinding wheel molding device (not shown). ), A control device 60, and a sizing device 90.

  The bed 10 has a substantially rectangular shape and is disposed on the floor. However, the shape of the bed 10 is not limited to a rectangular shape. A pair of Z-axis guide rails 11a and 11b are formed on the upper surface of the bed 10 so as to extend in the left-right direction (Z-axis direction) in FIG. The pair of Z-axis guide rails 11a and 11b are rails on which the table 20 can slide. Further, the bed 10 is provided with a Z-axis ball screw 11c for driving the table 20 in the left-right direction in FIG. 1 between the pair of Z-axis guide rails 11a and 11b. A Z-axis motor 11d that rotates is disposed.

  Further, on the upper surface of the bed 10, a pair of X-axis guide rails 12a and 12b on which the grindstone table 41 can slide are formed so as to extend in the vertical direction (X-axis direction) in FIG. Has been. Further, the bed 10 is provided with an X-axis ball screw 12c between the pair of X-axis guide rails 12a and 12b for driving the grinding wheel base 41 in the vertical direction in FIG. 1, and this X-axis ball screw 12c. An X-axis motor 12d that rotates the motor is disposed.

  The table 20 is formed in a long rectangular flat plate shape, and is slidably disposed on the pair of Z-axis guide rails 11 a and 11 b in the upper surface of the bed 10. The table 20 is connected to a nut member of the Z-axis ball screw 11c, and moves along the pair of Z-axis guide rails 11a and 11b by driving the Z-axis motor 11d. The Z-axis motor 11d has an encoder, and the encoder can detect the rotation angle of the Z-axis motor 11d.

  The headstock 30 is provided on the upper surface of the table 20 and supports the workpiece W in a rotatable manner. Specifically, the head stock 30 includes a head stock main body 31, a magnet chuck 32, a shoe 33, and a main shaft motor 34. The headstock body 31 is fixed to the left side of FIG. The headstock body 31 is provided with a magnet chuck 32 that can rotate about the Z-axis. The magnet chuck 32 attracts and holds a bearing, which is a workpiece W, by a magnetic force. The shoe 33 and the magnet chuck 32 are provided on the headstock 30, and the workpiece W is positioned by supporting the side surface of the workpiece W by the shoe 33. The magnet chuck 32 is rotationally driven with respect to the head stock body 31 by the main shaft motor 34. The main shaft motor 34 has an encoder, and the rotation angle of the main shaft motor 34 can be detected by the encoder.

  The grinding wheel support device 40 includes a grinding wheel base 41, a grinding wheel driving motor 42, and a grinding wheel 43. The grinding wheel base 41 is slidably disposed on the pair of X-axis guide rails 12a and 12b on the upper surface of the bed 10. The grindstone base 41 is connected to the nut member of the X-axis ball screw 12c, and moves along the pair of X-axis guide rails 12a and 12b by driving the X-axis motor 12d.

  A grinding wheel driving motor 42 is fixed to an end surface of the grinding wheel head 41 in the X-axis direction on the head stock 30 side. At the tip of the grinding wheel drive motor 42, a grinding wheel 43 for grinding the inner peripheral raceway surface of the bearing outer ring, which is the workpiece W, is provided. That is, the grinding wheel 43 is attached to the grinding wheel base 41 so as to be rotatable around the Z axis.

  The proximity switch 50 is a switch that is provided on the upper surface of the bed 10 and detects the start and end of the grinding cycle of the bearing outer ring that is the workpiece W by the grinding wheel 43. That is, the proximity switch 50 determines that the grinding cycle starts when the grinding wheel base 41 approaches the proximity switch 50 and the Z-axis direction separation distance between the proximity switch 50 and the grinding wheel base 41 becomes equal to or less than the set value. On the other hand, the proximity switch 50 determines that the grinding cycle is completed when the grinding wheel base 41 is moved away from the proximity switch 50 and the Z-axis direction separation distance between the proximity switch 50 and the grinding wheel base 41 exceeds a set value.

The contact detection sensor 80 is a sensor that is provided on the side surface of the headstock body 31 and detects the start of grinding of the bearing outer ring that is the workpiece W by the grinding wheel 43. That is, when the grinding wheel 43 contacts the workpiece W, the contact detection sensor 80 detects the contact and determines that grinding is started. For example, an AE sensor is used as the contact detection sensor 80.
In the second embodiment to be described later, the contact detection sensor 80 is used to determine whether to start collecting grinding load data. Instead of the contact detection sensor 80, it is possible to determine whether to start collecting grinding load data based on the X-axis position of the grindstone table 41 and the Z-axis position of the table 20.

  The grinding wheel molding device (not shown) is a dresser that is provided on the headstock 30 or the bed 10 and molds the outer peripheral surface of the grinding wheel 43, for example. The grinding wheel 43 dressed by this grinding wheel molding device is in a state of good sharpness and is formed in a desired shape.

  The sizing device 90 is provided on the upper surface of the table 20, and measures the inner diameter of the workpiece W at the grinding feed position when the grinding wheel 43 is grinding the inner peripheral raceway surface of the bearing outer ring which is the workpiece W. It is. This sizing device 90 is configured such that an L-shaped arm 91 extending from the device main body can be moved in the left-right direction and the up-down direction in FIG. 1 by a drive device (not shown), and a probe 92 attached to the tip of the arm 91 is provided. It is configured to be able to always contact the inner peripheral raceway surface of the bearing outer ring.

  The control device 60 controls each motor to rotate the workpiece W around the Z axis and rotate the grinding wheel 43. In addition, the control device 60 includes a grinding abnormality monitoring device 70 that monitors a grinding abnormality in a processing process in an initial stage of contact between the workpiece W and the grinding wheel 43, that is, a first roughing process. However, the grinding abnormality monitoring device 70 is not limited to the one provided inside the control device 60, and can also be applied as an external device. In the second embodiment, the control device 60 performs grinding of the inner peripheral raceway surface of the bearing outer ring, which is the workpiece W, by relatively moving the workpiece W and the grinding wheel 43 in the Z-axis direction and the X-axis direction. Perform adaptive control. Details will be described later.

(2. Explanation of grinding abnormality)
Next, the grinding abnormality monitored by the grinding abnormality monitoring device 70 will be described. Grinding anomalies include grinding burn (worked layer) that occurs when the grinding load is greater than a predetermined value. The thickness a of the damaged layer is, for example, as shown in FIG. 4, from a _n as grinding load P increases as P ₁ from P _n to thickened relationship with a _1.

  Here, an outline of a general relationship between the remaining grinding allowance R of the workpiece W and the grinding load P will be described with reference to FIG. The first roughing process is started by detecting contact between the workpiece W and the grinding wheel 43. The remaining grinding allowance at this time is Ro, and the grinding load is Po. In the first roughing process, the relative movement of the workpiece W and the grinding wheel 43 is performed at a constant speed from the contact of the workpiece W and the grinding wheel 43 to the entire surface, and the grinding wheel 43 of the workpiece W is used. Grind with a constant depth of cut. Therefore, in the first roughing process, as the grinding proceeds, the contact area per unit time between the workpiece W and the grinding wheel 43 increases, so that the grinding load P increases and the remaining grinding allowance R reaches Rp. At the end of the process, the maximum grinding load Pp is obtained.

  When the roughing process is started, the grinding load P is lowered and maintained when the predetermined grinding load Pa is reached. When the remaining grinding allowance R reaches Re, the roughing process is completed and the finishing process is started, and the grinding load P gradually decreases. Then, when the remaining grinding allowance R reaches 0, the finishing process ends.

  In the grinding abnormality monitoring device 70 of the present embodiment, it is determined whether or not the work-affected layer generated on the workpiece W at the end of the first roughing process can be removed by subsequent grinding. That is, in the first rough process in which generation of the work-affected layer is allowed, the maximum detected at the end of the first rough process based on the relationship between the grinding load P and the thickness a of the work-affected layer shown in FIG. The thickness of the work-affected layer corresponding to the grinding load Pp is obtained. Then, the obtained thickness of the work-affected layer is compared with the grinding remaining allowance Rp detected at the end of the first roughing process. When the thickness of the work-affected layer obtained does not exceed the detected grinding remaining allowance Rp, it is possible to remove the work-affected layer by subsequent grinding. Is determined to be normal. Further, when the thickness of the work-affected layer obtained exceeds the detected grinding remaining allowance Rp, it is impossible to remove the work-affected layer by subsequent grinding, so that it is determined to be abnormal. become. Therefore, the determination accuracy of grinding abnormality can be improved, and the grinding defect rate of the workpiece W can be reduced.

(3. Configuration of grinding abnormality monitoring device)
Next, the grinding abnormality monitoring device 70 will be described with reference to the functional block diagram of FIG. Here, in describing the grinding abnormality monitoring device 70, FIG. 2 also describes a partial configuration of the grinding machine 1 described above. Here, in FIG. 2, the same code | symbol is attached | subjected about the structure same as the structure of the grinding machine 1 of FIG. The grinding wheel driving motor 42 is provided with a motor wattmeter 42a for measuring the driving power of the grinding wheel driving motor 42. Instead of the motor wattmeter 42a, the power value may be directly collected by a motor amplifier of the grinding wheel driving motor 42.

  The grinding abnormality monitoring device 70 includes a remaining grinding allowance measuring unit 71, a grinding load calculation unit 72, a data storage unit 73, a first rough process completion notification unit 74, an abnormality determination unit 75, and an output unit 76. Configured.

  The grinding remaining machining allowance measuring unit 71 is based on the inner diameter of the workpiece W at the grinding feed position when the workpiece W read from the sizing device 90 is ground by the grinding wheel 43 at the end of the first roughing process. The allowance R is calculated.

The grinding load calculation unit 72 generates grinding by grinding the workpiece W with the grinding wheel 43 based on the driving power of the grinding wheel driving motor 42 taken from the motor wattmeter 42a at the end of the first roughing process. A load (hereinafter referred to as an actually measured grinding load Prn) is calculated. The grinding load Prn has a relationship that increases as the driving power of the grinding wheel driving motor 42 increases. As a method for calculating the grinding load Prn , in this embodiment, the driving power of the grinding wheel driving motor 42 is used, but the grinding load Prn can also be calculated as follows. For example, the grinding load Prn drives the current value of the grinding wheel drive motor 42, the current value of the X-axis motor 12d that performs relative movement between the grinding wheel 43 and the workpiece W, the power value, and the workpiece W to rotate. It can be calculated from the current value, power value of the spindle motor 34, the amount of deflection deformation of the grinding wheel 43 or the support portion of the workpiece W, and the like.

Further, the grinding load Prn can be calculated based on the deformation amount of the grinding part in the workpiece W, that is, the deflection displacement amount of the workpiece W caused by being pressed against the grinding wheel 43. This is because the amount of deflection displacement depends on the grinding load Prn . The deflection displacement amount of the grinding part in the workpiece W is measured by, for example, a displacement sensor.

Further, the grinding load Prn can be calculated from the temperature of the grinding part of the workpiece W. This is because the temperature depends on the grinding load Prn . However, it is not easy to measure the temperature of the workpiece W in contact with the grinding wheel 43, that is, the temperature of the grinding point. Therefore, the temperature of the portion of the workpiece W having a phase shifted from the grinding point (contact point with the grinding wheel 43) in the grinding portion (inner peripheral surface or outer peripheral surface) is measured. The temperature of the grinding part of the workpiece W differs depending on the phase deviated from the grinding point and the phase deviated from the grinding point, but the phase temperature deviated from the grinding point is a value corresponding to the temperature of the grinding point. Therefore, even a phase shifted from the grinding point can be measured sufficiently. And the temperature of the phase shifted | deviated from the grinding point among the grinding | polishing parts of the workpiece W is measured with the contact-type temperature sensor made to contact the said site | part, or the non-contact-type temperature sensor made non-contact with the said site | part.

The data storage unit 73 stores table data (see FIG. 4) of a relationship between a grinding load (hereinafter referred to as a grinding load Pdn for setting table data) actually measured by an operator and a thickness a of the work-affected layer. To do.

  When the first roughing process end notifying unit 74 receives from the control device 60 a signal indicating that the grinding of a predetermined cutting amount in the first roughing process commanded by the grinding program has been completed, the first roughing process end notifying part grinds. The remaining machining allowance measurement unit 71 and the grinding load calculation unit 72 are notified.

  The abnormality determination unit 75 determines the thickness ap of the work-affected layer corresponding to the grinding load Pp at the end of the first roughing process calculated by the grinding load calculation unit 72 based on the table data read from the data storage unit 73. . Then, when the thickness ap of the work-affected layer at the end of the first roughing process exceeds the remaining grinding allowance Rp at the end of the first roughing process, it is determined that the grinding is abnormal.

  When it is determined that there is a grinding abnormality, the output unit 76 displays information regarding the grinding abnormality on the screen of the display device 81, a printing process by the printing device 82, a storage process in the storage device 83, or a communication device. A communication output to an external device is performed by 84. The output is selected by the operator. Thereby, the operator can surely grasp the grinding abnormality by the output form selected by the worker for the information regarding the grinding abnormality.

(4. Processing by grinding abnormality monitoring device)
Next, execution of the grinding abnormality monitoring program by the grinding abnormality monitoring device 70 will be described with reference to FIG. The grinding abnormality monitoring program determines whether or not a grinding abnormality has occurred based on the thickness ap of the work-affected layer at the end of the first roughing process and the remaining grinding allowance Rp at the end of the first roughing process. This will be described in detail below.

As shown in FIG. 3, it is determined whether or not table data (see FIG. 4) of the relationship between the grinding load Pdn and the thickness a of the work-affected layer is already stored as data related to the work-affected layer (step S1). . If not yet stored, data relating to the work-affected layer is read (step S2).

  If data related to the work-affected layer is stored, a grinding cycle is started (step S3). When the grinding cycle is started, as shown in FIG. 2, the control device 60 drives each motor and starts grinding the inner circumferential raceway surface of the bearing outer ring as the workpiece W by the grinding wheel 43. More specifically, after starting the grinding cycle, as shown in FIG. 1, the grinding wheel base 41 is moved to the reference position (see FIG. 1) toward the position where the grinding wheel 43 can enter the inside of the bearing outer ring, which is the workpiece W, in the radial direction. (Not shown) is moved in the X-axis direction. Then, the grinding wheel 43 enters the radial inner side of the bearing outer ring, which is the workpiece W, by moving the table 20 in the Z-axis direction. Then, the grinding wheel 43 moves in the X-axis direction toward the inner circumferential raceway surface of the bearing outer ring, which is the workpiece W, and starts grinding. For grinding the workpiece W, the black skin is ground in the first roughing process, then the second roughing process is performed, and the finishing process is performed. When the grinding is finished, the operation is performed in the reverse order from the start of grinding, the process returns to the reference position, and the grinding cycle is finished.

  When the proximity switch 50 is in the ON state, that is, when the grinding cycle is started, the contact detection sensor 80 detects the contact between the workpiece W and the grinding wheel 43 and determines whether or not the first roughing process is started (step S4). ). Then, after the start of the first rough process (step S5), it is determined whether or not there is a notification that the first rough process has ended (step S6). Specifically, when the first roughing process end notification unit 74 shown in FIG. 2 receives a signal indicating that the grinding of a predetermined cutting amount in the first roughing process has been completed from the control device 60, the first roughing process end notification is sent. Is sent to the remaining grinding allowance measuring unit 71 and the grinding load calculating unit 72.

Then, when there is a notification that the first roughing process has been completed, the grinding remaining allowance Rp at the end of the first roughing process is measured and the grinding load Pp is calculated (step S7). Then, the thickness ap of the work-affected layer generated by the calculated grinding load Pp is read from the work-affected layer data (step S8). Specifically, the work-affected layer with respect to the grinding load Pp calculated by the grinding load calculation section 72 based on the relationship between the grinding load Pdn and the thickness a of the work-affected layer stored in the data storage section 73 shown in FIG. Read the thickness ap.

Then, a grinding abnormality determination at the end of the first roughing process is performed. That is, it is determined whether or not the remaining grinding allowance Rp at the end of the first roughing process exceeds the thickness _ap of the work-affected layer (step S9). If the remaining grinding allowance Rp at the end of the first roughing process does not exceed the thickness _ap of the work-affected layer, it is determined as normal (step S10), and the grinding cycle of the workpiece W is completed. A grinding cycle is executed (step S11).

  On the other hand, when the remaining grinding allowance Rp at the end of the first roughing process exceeds the remaining grinding allowance Rp in step S9, it is determined that grinding is abnormal, and the output unit 76 in FIG. Is displayed, and the abnormality content is stored in the storage device 83 (step S12). Then, the grinding cycle is stopped (step S13).

  On the other hand, in step S11, when the grinding cycle of the workpiece W is completed, it is determined whether or not there is the next workpiece W (step S14). The installation is set up (step S15), and the process is repeated from step S3. On the other hand, if there is no next workpiece W, the grinding cycle is stopped (step S13).

(5. History display status of display device screen)
Next, the history display state of the screen of the display device 81 will be described with reference to FIG. When a grinding abnormality occurs by executing the grinding abnormality monitoring program of FIG. 3 (step S10 of FIG. 3), the abnormality content is stored in the storage device 83. The storage device 83 may store normal contents as well as abnormal contents. When a large number of workpieces W are ground, the storage device 83 stores past abnormality histories. It can also be seen that the workpiece W that is not stored as a grinding abnormality is normal. Further, when normal contents are stored in the storage device 83, the normal workpiece W can be grasped directly.

  Then, as shown in FIG. 6, the screen of the display device 81 displays whether all the workpieces W are normal or abnormal in grinding. Thus, by storing the past history of information related to grinding abnormality, the tendency of grinding abnormality can be grasped. Therefore, by using the tendency of grinding abnormality, it is possible to predict the occurrence of grinding abnormality when performing future grinding. As a result, appropriate measures can be determined for future grinding.

As described above, according to the grinding abnormality monitoring method of the present embodiment, the remaining grinding allowance Rp at the end of the first roughing process is detected, and the grinding load Pp at the end of the first roughing process is detected. . Thereby, since grinding | polishing abnormality can be determined before performing the rough process after a 1st rough process, production efficiency can be improved.

In the above-described embodiment, on the assumption that the grinding load Pp at the end of the first roughing process becomes the maximum value, the thickness ap of the work-affected layer at the end of the first roughing process, and the first roughing process The configuration is such that the remaining grinding allowance Rp at the end of is compared. Instead, the maximum grinding load during the first roughing process is detected, the thickness of the work-affected layer corresponding to the grinding load, the remaining grinding allowance when the grinding load is detected, or at the end of the first roughing process The remaining grinding allowance Rp may be compared.

Further, the dimension of the workpiece W before grinding is measured in advance, and the remaining grinding allowance Rp at the end of the first roughing process is obtained from the known depth of cut in the first roughing process and the dimension of the workpiece. And it is good also as a structure which compares the grinding | polishing remaining allowance Rp which calculated | required with the thickness ap of the work-affected layer at the time of completion | finish of a 1st rough process. Further, when the obtained grinding remaining allowance Rp is large, it is possible to set the grinding load of the first roughing process higher than when it is small, and the production efficiency can be improved.

<Second embodiment>
Next, the grinding abnormality monitoring device of the second embodiment will be described. The grinding abnormality monitoring device 70 described above monitors a grinding abnormality that occurs at the end of the first roughing process. However, since the shape accuracy of the workpiece W before grinding varies, the contact area between the workpiece W and the grinding wheel 43 greatly varies in the first roughing process, and the grinding load also varies greatly. In some cases, a work-affected layer may occur. Therefore, in this embodiment, the grinding load threshold for the remaining grinding allowance is set during the first roughing process, and the grinding abnormality occurring during the first roughing process is monitored. This will be described in detail below.

(1. Explanation of threshold)
The threshold value P (R) set in the grinding abnormality monitoring device 170 will be described. In the conventional grinding abnormality monitoring device, a grinding load at which a work-affected layer does not occur in the workpiece W is set as a threshold value. However, in the grinding abnormality monitoring device 170 of this embodiment, the grinding W is generated in the first roughing process. A grinding load Pdn that can remove the processed damaged layer by subsequent grinding is set as a threshold value P (R) . That is, during the first roughing step , the threshold value P (R) that is the grinding load Pdn for the remaining grinding allowance R is set based on the relationship between the grinding load Pdn and the thickness a of the work-affected layer shown in FIG. For example, as shown in FIG. 9, the threshold value P (R) has a relationship of decreasing from Pp to Po as the remaining grinding allowance R decreases from Ro to Rp.

By setting this threshold value P (R) , even if a work-affected layer is generated on the workpiece W in the first roughing process, the work-affected layer can be removed by subsequent grinding. What has been determined to be present is determined to be normal. Further, when the grinding load Prn becomes larger than the threshold value P (R) , it becomes impossible to remove the work-affected layer by subsequent grinding, so that it is determined to be abnormal. Therefore, the grinding defect rate of the workpiece W can be reduced, and the determination accuracy of grinding abnormality can be improved.

(2. Configuration of grinding abnormality monitoring device)
The grinding abnormality monitoring device 170 in this embodiment will be described with reference to FIG. The grinding abnormality monitoring device 170 according to the present embodiment includes a remaining grinding allowance measuring unit 171, a grinding load calculation unit 172, a data storage unit 73 (similar to the first embodiment), a threshold setting unit 174, and an abnormality determination unit 75. (Similar to the first embodiment) and an output unit 76 (similar to the first embodiment).

  The remaining grinding allowance measuring unit 171 determines the remaining grinding allowance based on the inner diameter of the workpiece W at the grinding feed position when the workpiece W read from the sizing device 90 is ground by the grinding wheel 43 during the first roughing process. R is calculated.

The grinding load calculation unit 172 is a grinding load generated by grinding the workpiece W by the grinding wheel 43 based on the driving power of the grinding wheel driving motor 42 taken from the motor wattmeter 42a during the first roughing process. Prn is calculated. The grinding load Prn at this time is the same as in the first embodiment.

The threshold setting unit 174 is based on the relationship between the grinding load Pdn stored in the data storage unit 73 and the thickness a of the work-affected layer, and the remaining grinding during the first roughing process calculated by the remaining grinding allowance measuring unit 171. A threshold value P (R) that is a grinding load Pdn for the machining allowance R is set.

(3. Processing by grinding abnormality monitoring device)
The processing by the grinding abnormality monitoring device 170 will be described with reference to FIG. It is determined whether or not table data (see FIG. 4) regarding the relationship between the grinding load Pdn and the thickness a of the work-affected layer is already stored as threshold setting data (step S21). If not stored yet, threshold setting data is read (step S22).

  If threshold setting data is stored, a grinding cycle is started (step S23). When the grinding cycle is started, as shown in FIG. 7, the control device 60 drives each motor and starts grinding the inner peripheral raceway surface of the bearing outer ring as the workpiece W by the grinding wheel 43.

  After the grinding cycle is started, the remaining grinding allowance Rs when the workpiece W is ground by the grinding wheel 43 is measured (step S24). Specifically, based on the inner diameter of the workpiece W at the grinding feed position when the grinding wheel 43 is used to grind the workpiece W read from the sizing device 90 by the remaining grinding allowance measuring unit 171 shown in FIG. The machining allowance Rs is measured.

Then, a threshold value P (R) for each remaining grinding allowance Rn is selected from the threshold setting data from FIG. 4, and a grinding load at each remaining grinding allowance Rn (hereinafter referred to as Psn for setting a target value for condition change). A value smaller than the threshold value P (R) by a predetermined amount is set (step S25). Specifically, each remaining grinding allowance Rn measured by the remaining grinding allowance measuring unit 171 based on the relationship between the grinding load Pdn and the thickness a of the work-affected layer stored in the data storage unit 73 shown in FIG. Is selected, and the grinding load Psn at each remaining grinding allowance Rn is set to a value smaller than the threshold P (R) by a predetermined amount .

Proximity switch 50 is ON, i.e. After grinding cycle is initiated, the contact detection sensor 80 starts to determine whether or not contact is detected between the workpiece W and the grinding wheel 43 (step S26).

  Then, when the contact detection sensor 80 detects contact between the workpiece W and the grinding wheel 43, that is, when the first roughing process is started (step S26: Yes), it is determined whether or not the remaining grinding allowance Rn has become Rp. (Step S27).

If the remaining grinding allowance Rn is not Rp, that is, if the first roughing process has not been completed, the threshold value P (R) at the remaining grinding allowance Rn is read from the threshold setting data (step S28). Specifically, with respect to the remaining grinding allowance Rn measured by the remaining grinding allowance measuring unit 171 based on the relationship between the grinding load Pdn and the thickness a of the work-affected layer stored in the data storage unit 73 shown in FIG. The threshold value P (R) is read.

Then, immediately after reading the threshold value P (R) , grinding abnormality determination is performed (step S29). That is, the grinding condition of the grinding wheel 43, for example, the grinding feed speed of the grinding wheel 43, so that the grinding load Prn for the remaining grinding allowance Rn does not exceed the threshold value P (R) and becomes smaller than the threshold value P (R). And adaptive control for changing the rotational speed, the rotational speed of the workpiece W, and the like . When the grinding load Prn at the current time of the roughing process exceeds the threshold value P (R), the grinding abnormality is determined.

Specifically, as shown in FIG. 9, not exceed the threshold value P (R), and sets a threshold P target value for the condition change is near ground load Psn the (R) Q (R), this condition change The grinding conditions are changed so that the target value Q (R) is obtained . If the grinding load Prn for the remaining grinding allowance Rn does not exceed the threshold value P (R), it is determined as normal (step S30), and the process returns to step S27 to perform the above-described processing.

On the other hand, if the grinding load Prn for the remaining grinding allowance Rn exceeds the threshold value P (R) in step S29, it is determined that the grinding is abnormal, and the output unit 76 in FIG. Then, the abnormal content is stored in the storage device 83 (step S33). Then, the grinding cycle is stopped (step S34).

  On the other hand, when the remaining grinding allowance Rn becomes Rp in step S27, that is, when the first roughing process is completed, the process proceeds to the second roughing process and further to the finishing process (step S31).

  When the proximity switch 50 is in the OFF state, that is, when the grinding cycle is completed (step S32), it is determined whether or not there is a next workpiece W (step S35). The installation of the object W is set up (step S36), and the processing is repeated from step S23. On the other hand, if there is no next workpiece W, the grinding cycle is stopped (step S34).

As described above, in the first roughing step, the threshold value P (R) that is the grinding load Pdn for the remaining grinding allowance Rn is set based on the relationship between the grinding load Pdn and the thickness a of the work-affected layer. Also, this grinding abnormality monitoring device 170 can provide the same effects as the grinding abnormality monitoring device 70 of the first embodiment.

  In addition, although the contact detection sensor 80 was used in the above embodiment to determine the collection start and collection end of grinding cycle load data, the grindstone base 41 and the table 20 are set in advance without using the contact detection sensor 80. It can also be performed by moving to the X-axis position and the Z-axis position.

1: grinding machine 10: bed, 11a, 11b: Z-axis guide rail, 11c: Z-axis ball screw 11d: Z-axis motor, 12a, 12b: X-axis guide rail, 12c: X-axis ball screw 12d: X-axis motor 20 : Table 30: Headstock, 31: Main body, 32: Magnet chuck 33: Shoe, 34: Spindle motor 40: Wheel support device, 41: Wheel head, 42: Motor for driving the grinding wheel 42a: Motor wattmeter, 43 : Grinding wheel 50: Proximity switch 60: Control device 80: Contact detection sensor 90: Sizing device 70: Grinding abnormality monitoring device 71: Remaining grinding allowance measuring unit 72: Grinding load calculation unit 73: Data storage unit 74: First rough process end notification unit 75: Abnormality determination unit 76: Output unit 170: Grinding abnormality monitoring device 171: Grinding remaining allowance measuring unit 172: Grinding load calculation Output unit 174: threshold setting unit

Claims (7)

In a grinding abnormality monitoring method for monitoring a grinding abnormality by using a grinding machine that grinds the workpiece by relatively moving a workpiece and a grinding wheel,
A remaining grinding allowance detecting step for detecting a remaining grinding allowance when grinding the workpiece in a processing step in an initial contact between the workpiece and the grinding wheel;
A grinding load detection step of detecting a grinding load when grinding the workpiece in the machining step in the initial stage of contact;
The thickness of the work-affected layer corresponding to the detected grinding load is determined based on a relationship in which the thickness of the work-affected layer of the work changes when the grinding load when grinding the work is changed , and obtained. The thickness of the work-affected layer is compared with the detected remaining grinding allowance to determine whether the work-affected layer generated on the workpiece can be removed by grinding after the occurrence of grinding. Grinding abnormality judging step for judging
Grinding abnormality monitoring method comprising: In claim 1,
The remaining grinding allowance detection step detects the remaining grinding allowance at the end of the processing step of the initial contact,
The grinding load detection step detects the grinding load at the end of the processing step at the initial contact stage,
A grinding abnormality monitoring method in which the grinding abnormality determination step determines that there is a grinding abnormality when the thickness of the work-affected layer corresponding to the detected grinding load exceeds the detected grinding remaining allowance. In a grinding abnormality monitoring method for monitoring a grinding abnormality by using a grinding machine that grinds the workpiece by relatively moving a workpiece and a grinding wheel,
A remaining grinding allowance detecting step for detecting a remaining grinding allowance when grinding the workpiece in a processing step in an initial contact between the workpiece and the grinding wheel;
A grinding load detection step of detecting a grinding load when grinding the workpiece in the machining step in the initial stage of contact;
Based on the relationship in which the thickness of the work-affected layer of the workpiece changes when the grinding load when grinding the workpiece changes, and the remaining grinding allowance when grinding the workpiece , the workpiece generated on the workpiece A threshold setting step for setting a grinding load that can be removed by grinding after generation of the work-affected layer as a threshold according to the grinding remaining allowance ;
A grinding abnormality determination step for determining that there is a grinding abnormality when the grinding load in the detected grinding remaining allowance exceeds the threshold value corresponding to the detected grinding remaining allowance;
Grinding abnormality monitoring method comprising. In claim 3,
The grinding abnormality monitoring method is:
A control step of changing grinding conditions of the grinding wheel,
With
The control step is a grinding abnormality monitoring method in which the grinding condition of the grinding wheel is changed so that the detected grinding load does not exceed the threshold value and approaches the threshold value. In any one of Claims 1-4,
The processing step in the initial stage of contact is a grinding abnormality monitoring method in which the relative movement between the workpiece and the grinding wheel is performed at a constant speed and the cutting amount of the workpiece by the grinding wheel is constant. In a grinding abnormality monitoring device that monitors a grinding abnormality by using a grinding machine that grinds the workpiece by relatively moving the workpiece and the grinding wheel,
Remaining grinding allowance detecting means for detecting a remaining grinding allowance when grinding the workpiece in the initial machining step of contact between the workpiece and the grinding wheel;
A grinding load detection means for detecting a grinding load when grinding the workpiece in the machining process in the initial stage of contact;
The thickness of the work-affected layer corresponding to the detected grinding load is determined based on a relationship in which the thickness of the work-affected layer of the work changes when the grinding load when grinding the work is changed , and obtained. The thickness of the work-affected layer is compared with the detected remaining grinding allowance to determine whether the work-affected layer generated on the workpiece can be removed by grinding after the occurrence of grinding. Grinding abnormality judging means for judging,
Grinding abnormality monitoring device comprising:   In a grinding abnormality monitoring device that monitors a grinding abnormality by using a grinding machine that grinds the workpiece by relatively moving the workpiece and the grinding wheel,
  Remaining grinding allowance detecting means for detecting a remaining grinding allowance when grinding the workpiece in the initial machining step of contact between the workpiece and the grinding wheel;
  A grinding load detection means for detecting a grinding load when grinding the workpiece in the machining process in the initial stage of contact;
  Based on the relationship in which the thickness of the work-affected layer of the workpiece changes when the grinding load when grinding the workpiece changes, and the remaining grinding allowance when grinding the workpiece, the workpiece generated on the workpiece A threshold setting means for setting a grinding load that can be removed by grinding after generation of the work-affected layer as a threshold according to the grinding remaining allowance;
  Grinding abnormality determining means for determining that there is a grinding abnormality when the grinding load in the detected remaining grinding allowance exceeds the threshold corresponding to the detected remaining grinding allowance;
  Grinding abnormality monitoring device comprising:

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