Processing device

Abstract

The invention provides a machining device capable of improving the finishing precision of forming a tool for machining a workpiece. A gear grinding device (10) is provided with: a grindstone (20) for machining a workpiece (W); a dressing tool that can be brought into contact with and separated from the grindstone (20), and that cuts the grindstone (20) from a dressing reference position by a predetermined amount of feed, thereby performing dressing for molding the grindstone (20); an AE sensor, the output level of which changes according to the contact between the grindstone (20) and the dressing tool; and a control unit that monitors the contact between the grindstone (20) and the dressing tool on the basis of the output of the AE sensor. The control unit causes the grindstone (20) and the dressing tool to relatively approach each other in the earlier stage of dressing, monitors the contact between the grindstone (20) and the dressing tool on the basis of the output of the AE sensor, and determines a dressing reference position on the basis of information on the monitored contact position.

Description

TECHNICAL FIELD

[0001] The present application relates to a processing device. Particularly, the present application relates to a countermeasure for achieving improvement of dressing accuracy of a tool for processing a workpiece by dressing a tool with a dressing tool. BACKGROUND

[0002] For example, as disclosed in Patent Literature 1, in a processing device such as a gear grinding device, there is provided a tool (for example, a grinding stone) for processing (grinding processing) a workpiece (for example, a gear), and at a timing at which the number of times of processing of the workpiece by the tool reaches a prescribed number of times, dressing is performed in which a tool is dressed by a dressing tool. The processing accuracy of the workpiece by the tool is maintained by performing the dressing.

[0003] Specifically, in the dressing of the gear grinding device, a cylindrical grinding stone and a dressing tool having a rotation axis parallel to the rotation axis of the grinding stone are opposed in a manner that they can be brought into contact and separated from each other, and the two are brought into contact from a reference position at which the dressing is started (for example, the grinding stone is brought close to the dressing tool by a prescribed dimension that is prescribed in advance), and thereby the grinding stone is dressed by the dressing tool by cutting the grinding stone by a feed amount that is prescribed in advance, and the grinding stone is dressed.

[0004] Furthermore, after the dressing is completed, when the grinding processing of the gear by the grinding stone is performed, it is conceivable that the outer diameter dimension of the grinding stone is reduced by the feed amount due to the dressing, and thereby the position of the grinding stone is advanced (the grinding stone is brought close to the workpiece) by the feed amount (the calculated feed amount) with respect to the position before the dressing, and the grinding processing of the workpiece is started.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2001-269815

[0008] Patent Literature 2: Japanese Patent Application Publication No. 2020-199620 SUMMARY

[0009] As described above, the dressing is performed every time the grinding of the gear by the stone reaches a predetermined number of times, but the axial distance between the stone and the dressing tool can change during the grinding of the gear (from the last dressing to the present dressing). As a cause thereof, there can be mentioned thermal expansion of each part of the processing device due to changes in the temperature of the machine body and the temperature of the cutting oil due to changes in the room temperature, or changes in the temperature of the cutting oil due to the heat generated from the high-pressure cutting fluid pump and the grinding heat, and the like. In addition, there can be mentioned a cause in which the upper surface of the base of the unit supporting the stone changes in level due to the influence of heat, resulting in inclination of the pillars (generally called columns) of the unit. As an example, there can be mentioned a cause in which the axial distance increases if the temperature of the equipment increases, and, conversely, the axial distance decreases if the temperature of the equipment decreases.

[0010] If the axial distance between the stone and the dressing tool changes in this way, the actual reference position at which the dressing starts changes with respect to the calculated reference position, and, in correspondence with this change, the amount of feed of the dressing tool to the stone can deviate from the amount of feed targeted. That is, the shape of the stone after the forming (the finished diameter of the stone) can deviate from the calculated value. This deviation in the shape of the stone has an influence on the amount of processing of the gear by the stone thereafter, resulting in a problem in which the OBD (Over Ball Diameter) of the gear deviates from the designed value.

[0011] As one of the countermeasures for solving the problem, there can be mentioned a countermeasure in which the axial distance is measured by a contact probe or a contact sensor, and the difference with respect to the last value of the axial distance is reflected as a correction amount of the cutting at the time of the dressing. However, in this case, a measurer such as a contact probe or a contact sensor, a member for mounting thereof, a sliding housing mechanism, and the like are required, and various problems can occur in which the cost of the entire device increases, or the movement of each part of the processing device is restricted in order to avoid contact with the newly added member, and the like. In addition, since the actual processing point (the reference position at which the dressing starts) is not directly measured, there is a limit in improving the dressing accuracy.

[0012] This problem is not limited to the gear grinding device, and the same problem occurs in various processing devices such as a honing device, and the like, which perform dressing in which a tool is formed using a dressing tool.

[0013] Until now, no countermeasure has been proposed for achieving improvement in the dressing accuracy with respect to changes in the axial distance between the tool and the dressing tool due to the influence of heat.

[0014] The present application has been achieved in view of the above problems, and an object thereof is to provide a processing device capable of achieving improvement in the dressing accuracy of a tool formed by processing a workpiece.

[0015] The solution of the present application for achieving the object is characterized by: a tool for machining a workpiece; a dressing tool capable of relatively contacting and separating with respect to the tool, performing dressing of the tool by cutting the tool by a prescribed amount of feed from a dressing reference position to perform shaping of the tool; a sensor whose output level changes according to contact of the tool and the dressing tool; and a control section that performs contact monitoring of the tool and the dressing tool based on the output of the sensor, the control section performing reference position decision processing that, in an early stage of performing the dressing, relatively approaches the tool and the dressing tool, monitors contact of the tool and the dressing tool based on the output of the sensor, and decides the dressing reference position based on information of the monitored contact position.

[0016] According to this particular matter, in an early stage of performing dressing of the tool, the dressing reference position is decided based on information of the position of contact of the tool and the dressing tool, and the tool is cut by a prescribed amount of feed using the dressing tool from the dressing reference position to perform shaping of the tool. That is, even in a situation where the distance between the tool and the dressing tool (axial distance or the like) changes due to the influence of heat, the position decided based on the information of the position of contact of the tool and the dressing tool is used as the dressing reference position to cut and shape the tool by a prescribed amount of feed, and thus the tool can be cut by the prescribed amount of feed targeted without being affected by the change in the distance. As a result, the shape of the tool after dressing (for example, the finish diameter) can be appropriately obtained, and the machining accuracy of the tool with respect to the workpiece can be maintained high.

[0017] Effects of the Invention

[0018] In the present application, in an early stage of performing dressing of the tool using the dressing tool, contact of the tool and the dressing tool is monitored based on the output of the sensor, and the dressing reference position is decided based on information of the monitored contact position. Thus, the shape of the tool after dressing (for example, the finish diameter) can be appropriately obtained, and the machining accuracy of the tool with respect to the workpiece can be maintained high. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a perspective view of a gear grinding device according to an embodiment.

[0020] Figure 2 is a view showing the engagement state of the grinding stone and the workpiece at the time of grinding machining of the workpiece.

[0021] Figure 3 is a view showing the engagement state of the grinding stone and the dressing tool at the time of dressing the grinding stone.

[0022] Figure 4 is a cross-sectional view of a rotating shaft including a grinding stone of a grinding stone support unit.

[0023] Figure 5 is a block diagram showing a control system for performing dressing.

[0024] Figure 6 is a graph showing an AE waveform signal when a grinding stone and a dressing tool come into contact.

[0025] Figure 7 is a graph showing an ideal AE waveform signal and an example of an actual AE waveform signal at the time of dressing.

[0026] Figure 8 is a flowchart showing a control sequence at the time of dressing of the embodiment.

[0027] Figure 9 is a flowchart showing a control sequence at the time of dressing of the modification example.

[0028] Figure 10 is a graph corresponding to Figure 5 of Modification Example 3.

[0029] Figure 11 is a graph corresponding to Figure 8 of Modification Example 3.

[0030] Explanation of Reference Numerals

[0031] 10 Gear grinding device (processing device)

[0032] 20 Grinding stone (tool)

[0033] 210 AE sensor (sensor)

[0034] 331 Dressing tool

[0035] 4 Control unit

[0036] 41 Normal dressing waveform storage unit (storage unit)

[0037] W Workpiece DETAILED DESCRIPTION

[0038] Hereinafter, an embodiment of the present application will be described based on the drawings. Furthermore, in the present embodiment, a case where the present application is applied to a gear grinding device that performs grinding processing of a gear as a workpiece will be described.

[0039] -Outline Structure of Gear Grinding Device-

[0040] Figure 1 is a perspective view showing main parts of a gear grinding device 10 to which the present embodiment is applied. In the present embodiment, in order to facilitate the description, as shown in Figure 1The front-rear direction, the left-right direction, and the up-down direction are defined as shown. Further, the detailed structure of the mechanism of the gear grinding device 10 is disclosed in, for example, Patent Literature 2, and the mechanism of the gear grinding device 10 will be simply described below.

[0041] The gear grinding device 10 performs grinding processing while synchronously rotating a workpiece W as a processing target and the grinding stone 20 as a tool, and includes a base 1, and a grinding stone support unit 2 and a workpiece processing unit 3 disposed on the base 1. The grinding stone support unit 2 supports the grinding stone 20 so as to be rotatable. The workpiece processing unit 3 includes a main shaft 30 and a support column 31, a center bit 32, and a dressing device 33 integrally and rotatably supported on the support column 31. Figure 1 In the present embodiment, the rotational axis direction of the grinding stone 20 is defined as the front-rear direction. A thread-like groove is formed in the outer circumferential surface of the grinding stone 20.

[0042] The workpiece processing unit 3 includes a main shaft 30 and a support column 31, a center bit 32, and a dressing device 33 integrally and rotatably supported on the support column 31. In the case of performing grinding processing on the workpiece W, the center bit 32 is positioned above the main shaft 30 by the rotation of the support column 31, and the workpiece W is supported by the main shaft 30 and the center bit 32 in a manner of sandwiching the workpiece W. The supported workpiece W is rotatable in the up-down direction as the rotational axis direction by the rotational drive of the main shaft 30. As shown in Figure 2 The gear grinding device 10 can synchronously drive the grinding stone 20 and the workpiece W while engaging them to grind the tooth surface of the workpiece W.

[0043] The dressing device 33 is used in the case of performing dressing of the grinding stone 20. In order to regenerate the sharpness of the thread-like groove of the grinding stone 20 after continuously processing a predetermined number of workpieces W, the dressing is performed as shown in Figure 3 The dressing device 33 is used in the case of performing dressing of the grinding stone 20. In order to regenerate the sharpness of the thread-like groove of the grinding stone 20 after continuously processing a predetermined number of workpieces W, the dressing is performed as shown in

[0044] The grinding stone support unit 2 is movable in the left-right direction, and performs grinding processing of the workpiece (gear) W by bringing the rotating grinding stone 20 into contact with the workpiece W at the time of grinding processing. In addition, the grinding stone 20 is brought into contact with the dressing tool 331 at the time of dressing to perform the molding (dressing) of the grinding stone 20.

[0045] Here, the dressing and the grinding processing of the workpiece W after the dressing are simply explained. With respect to the dressing, the grinding stone 20 and the dressing tool 331 are opposed in a manner that they can be relatively contacted and separated, and the two are contacted from a reference position at which the dressing is started (the rotating grinding stone 20 is brought close to the dressing tool 331 by a predetermined prescribed dimension), whereby the grinding stone 20 is shaped by cutting the grinding stone 20 with the dressing tool 331 by a predetermined feed amount. At this time, since the grinding stone 20 has the thread-like grooves, with respect to the grinding stone support unit 2, the grinding stone 20 is slid in the front-rear direction while the engagement state of the grinding stone 20 and the dressing tool 331 is maintained. That is, the grinding stone 20 is slid in the front-rear direction, whereby the relative position of the dressing tool 331 with respect to the grinding stone 20 is moved from one end side to the other end side in the direction along the rotational axis of the grinding stone 20, and the entire grinding stone 20 is cut. Further, with respect to the actual dressing, the cutting of the grinding stone 20 is repeatedly performed by the dressing tool 331 by a plurality of times, and the finished diameter of the grinding stone 20 is shaped to the target diameter. For example, the feed amount of one cutting operation is set to 5 μm, and in the case where the cutting operation is repeated 10 times, the finished diameter of the grinding stone 20 is reduced by 0.1 mm. Moreover, after the dressing is finished, when the grinding processing of the workpiece W (the processing of the gear) is performed with the grinding stone 20, it is assumed that the position of the grinding stone 20 is advanced toward the workpiece W (the grinding stone support unit 2 is moved to the right side) by the dimension of the feed amount twice as large as the dimension by which the outer diameter dimension of the grinding stone 20 is reduced due to the dressing, and the grinding processing of the workpiece W is started.

[0046] Figure 4 is a cross-sectional view of the grinding stone support unit 2 including the rotational axis of the grinding stone 20. As shown in Figure 4 , the grinding stone support unit 2 is provided with an automatic balancer 21 that automatically corrects the balance of the grinding stone 20 in rotation. In the present embodiment, with respect to the automatic balancer 21, an AE sensor 210 for performing contact monitoring of the grinding stone 20 is included (refer to Figure 5 ). The AE sensor 210 detects the acoustic resonance (elastic wave) generated when the grinding stone 20 contacts the workpiece W or the dressing tool 331 and converts it into an electric signal to output.

[0047] As described above, during repeated grinding processing of the workpiece W, the temperature of the machine body changes due to changes in the room temperature and the like, and thus the axial distance between the grinding stone 20 and the dressing tool 331 can change. In the related art, if the axial distance between the grinding stone 20 and the dressing tool 331 changes in this way, the actual reference position at which dressing starts (dressing reference position) at the start of dressing changes with respect to the calculated reference position, and in correspondence with the amount of change thereof, the amount of feed of the dressing tool 331 to the grinding stone 20 deviates from the amount of feed set as a target, and the shape of the grinding stone 20 after forming (the finish diameter of the grinding stone) can deviate from the calculated value. As a result, it can not be possible to appropriately obtain the OBD of the gear.

[0048] The present embodiment achieves an improvement in dressing accuracy in view of this point.

[0049] Figure 5 is a block diagram illustrating a control system for performing dressing. As this Figure 5 is shown, the gear grinding device 10 has a control section 4 that includes a normal dressing waveform storage section 41, a contact determination section 42, a dressing control section 43, a reference position coordinate adjustment section 44, a dressing waveform determination section 45, a reference position determination processing retry section 46, and an alarm output section 47.

[0050] The normal dressing waveform storage section 41 stores, in advance, an AE waveform signal that should be output from the AE sensor 210 in a state in which the grinding stone 20 is cut by the dressing tool 331 with an appropriate amount of feed (a waveform shown by a solid line in Figure 7 , hereinafter referred to as an ideal AE waveform signal. Further, Figure 7 The ideal AE waveform signal shown in

[0051] The contact determination section 42 is a functional section that, at an early stage of performing dressing, when the grinding stone 20 and the rotating dressing tool 331 are relatively brought close in a state in which the phases thereof are aligned, monitors contact of the above-described grinding stone 20 and dressing tool 331 based on the AE waveform signal output from the AE sensor 210.

[0052] Figure 6 is a graph illustrating an AE waveform signal at the time of contact of the grinding stone 20 and the dressing tool 331. In this Figure 6In this context, S1 is the AE waveform signal output by the AE sensor 210, and THc is the contact threshold used for contact monitoring by comparing it with the AE waveform signal S1. Essentially, when no contact occurs between the grinding stone 20 and the dressing tool 331, the waveform level (output level) of the AE waveform signal S1 is lower than the contact threshold THc. If contact occurs between the grinding stone 20 and the dressing tool 331, the waveform level of the AE waveform signal S1 rises sharply and exceeds the contact threshold THc. When the waveform level of the AE waveform signal S1 exceeds the contact threshold THc, the contact determination unit 42 determines that the grinding stone 20 and the dressing tool 331 are in contact at that time point and stores the coordinate position of the grinding stone 20 at that time point (e.g., the coordinate position of the grinding stone support unit 2 moving to the right).

[0053] Furthermore, the contact determination action here is performed appropriately (e.g., by adjusting the dressing tool 331) Figure 3 The process is performed with the grinding stone 20 engaged in a threaded groove to ensure phase alignment. Furthermore, the phase between the grinding stone 20 and the dressing tool 331 is defined as the phase at which the dressing tool 331 engages with the threaded groove of the grinding stone 20 at the central position along the rotation axis of the grinding stone 20. That is, regarding the contact determination operation, the presence or absence of contact between the grinding stone 20 and the dressing tool 331 is determined each time at approximately the same phase position.

[0054] The dressing control unit 43 is a functional unit that controls the aforementioned dressing action. As is well known, the control of this dressing action includes control of the phase alignment of the grinding stone 20 and the dressing tool 331, control of the rotation of the grinding stone 20, control of the forward movement of the grinding stone 20, and control of the sliding of the grinding stone 20 in the back-and-forth direction.

[0055] The reference position coordinate adjustment unit 44 compares the coordinate position of the grinding stone 20 at the contact time point (the contact time point between the grinding stone 20 and the dressing tool 331) determined by the contact determination unit 42 (hereinafter referred to as the current contact coordinate position) with the dressing reference position used in the previous dressing (hereinafter referred to as the previous dressing reference position), and determines the dressing reference position for this dressing based on the comparison result.

[0056] Specifically, in a case where the deviation between the last dressing reference position and the present contact coordinate position is smaller than a prescribed threshold value (for example, 5 μm) (a case where the deviation between the last dressing reference position and the contact position acquired through the present reference position decision process is smaller than a prescribed threshold value in the present invention), the last dressing reference position is decided as the dressing reference position for the next dressing (the next dressing reference position). For example, in a case where the change in the axial distance due to the influence of heat is small, the last dressing reference position is decided as the next dressing reference position. On the other hand, in a case where the deviation between the last dressing reference position and the present contact coordinate position is equal to or greater than a prescribed threshold value (for example, 5 μm) (a case where the deviation between the last dressing reference position and the contact position acquired through the present reference position decision process is equal to or greater than a prescribed threshold value in the present invention), the present contact coordinate position is decided as the dressing reference position for the next dressing (the next dressing reference position). For example, in a case where the change in the axial distance due to the influence of heat is large, the present contact coordinate position is decided as the next dressing reference position. Hereinafter, the process of deciding the dressing reference position in this way is referred to as a reference position decision process (a reference position decision process of monitoring the contact of the tool and the dressing tool based on the output of the sensor and deciding the dressing reference position based on the information of the monitored contact position in the present invention).

[0057] The dressing waveform decision section 45 is a functional section that, in a case where dressing of the grindstone 20 is started with a prescribed infeed amount with respect to the next dressing reference position decided through the reference position decision process, compares the AE waveform signal output from the AE sensor 210 (hereinafter referred to as the actual AE waveform signal) and the ideal AE waveform signal (the AE waveform signal that should be output from the AE sensor 210 in the case where the grindstone 20 is cut with an appropriate infeed amount by the dressing tool 331) stored in the normal dressing waveform storage section 41, and decides whether or not the signals are similar. Also, in a case where the actual AE waveform signal and the ideal AE waveform signal are similar, it is decided that the dressing has been performed normally. As a condition for deciding that the actual AE waveform signal and the ideal AE waveform signal are not similar, for example, a state in which the waveform level of the actual AE waveform signal is equal to or less than a prescribed value (including a case where the waveform level is zero) is continued, or the waveform level of the actual AE waveform signal exceeds a prescribed upper threshold value can be cited. Figure 7 The actual AE waveform signal indicated by the single-dot chain line shows a case where the waveform level exceeds a prescribed upper threshold value.

[0058] The reference position determination processing retry unit 46 is a functional unit that, during the first cutting action in the trimming process, if the trimming waveform determination unit 45 determines that the actual AE waveform signal and the ideal AE waveform signal are not similar, the reference position determination processing is performed again. That is, the aforementioned processing using the contact determination unit 42 and the reference position coordinate adjustment unit 44 is performed again, and then trimming is performed.

[0059] The alarm output unit 47 has the following function: when the reference position determination processing is performed again by the reference position determination processing retry unit 46, it repeatedly performs the processing that determines that the actual AE waveform signal and the ideal AE waveform signal are dissimilar. If the number of times reaches a predetermined value, it outputs an alarm instead of performing the reference position determination processing again. Examples of such alarms include alarm displays on the monitor screen of the gear grinding device 10 and voice-based warnings.

[0060] If the actual AE waveform signal and the ideal AE waveform signal are determined to be dissimilar, the reference position determination process is performed again and the alarm is output. This is equivalent to the abnormal situation handling described in this invention (the process of stopping the adjustment and re-performing the reference position determination process and the process of stopping the adjustment and issuing an alarm).

[0061] -Touching and finishing-

[0062] Next, according to Figure 8 The flowchart illustrates the sequence of dressing processes for the gear grinding apparatus 10 configured as described above.

[0063] If the grinding stone 20 has performed a specified number of grinding operations on the workpiece W and the dressing process begins, the phase alignment of the grinding stone 20 and the dressing tool 331 is first performed in step ST1. That is, by sliding the grinding stone 20 in the back-and-forth direction, the phase alignment is performed at the central part along the rotation axis of the grinding stone 20 in such a way that the dressing tool 331 engages with the threaded groove of the grinding stone 20.

[0064] Then, in step ST2, while the dressing tool 331 is rotating, the grinding stone 20 is moved forward toward the dressing tool 331 (the grinding stone support unit 2 is moved to the right).

[0065] In step ST3, it is determined whether the waveform level of the AE waveform signal S1 output from the AE sensor 210 exceeds the contact threshold value THc. As described previously, the waveform level of the AE waveform signal S1 exceeds the contact threshold value THc when the grinding stone 20 and the dressing tool 331 are in contact, and thus it is possible to determine that the grinding stone 20 and the dressing tool 331 are in contact at this point in time. In the case where YES is determined in step ST3 because the waveform level of the AE waveform signal S1 exceeds the contact threshold value THc, the processing proceeds to step ST4, and the coordinate position of the grinding stone 20 at this point in time (the coordinate position of the grinding stone support unit 2 in the left-right direction: the contact coordinate position this time) is stored.

[0066] In step ST5, the contact coordinate position this time stored in step ST4 and the last dressing reference position are compared, and it is determined whether the deviation therebetween is equal to or greater than a prescribed threshold value A (for example, 5 μm).

[0067] In the case where YES is determined in step ST5, the processing proceeds to step ST6, and the contact coordinate position this time is decided as the next dressing reference position. That is, the dressing reference position is updated (the next dressing reference position is updated), and the processing proceeds to step ST7. On the other hand, in the case where NO is determined in step ST5, the dressing reference position is not updated (the last dressing reference position is decided as the next dressing reference position: the next dressing reference position is not updated), and the processing proceeds to step ST7.

[0068] In step ST7, the dressing is started. That is, the rotating grinding stone 20 is brought close to the dressing tool 331 from the dressing reference position (the next dressing reference position) by a prescribed dimension prescribed in advance, and the grinding stone 20 is shaped by the dressing tool 331 by cutting the grinding stone 20 by a feed amount prescribed in advance (for example, 5 μm).

[0069] In step ST8, in the first cutting operation in the dressing, it is determined whether the actual AE waveform signal obtained from the output of the AE sensor 210 is similar to the ideal AE waveform signal stored in the normal dressing waveform storage section 41.

[0070] In the case where YES is determined in step ST8 because the actual AE waveform signal and the ideal AE waveform signal are similar (for example, a state in which the waveform level of the actual AE waveform signal is equal to or less than a prescribed value continues, or the waveform level of the actual AE waveform signal does not exceed a prescribed upper threshold value), the processing proceeds to step ST9, and the dressing is continued, and after the cutting operation of the grinding stone 20 by the dressing tool 331 is repeated a prescribed number of times, the dressing is ended, and the grinding of the workpiece W next time is started. That is, the position of the grinding stone 20 is advanced with respect to the position before the dressing toward the workpiece W (the grinding stone support unit 2 is moved to the right side) by the dimension cut away by the dressing, and thus the grinding of the workpiece W is started.

[0071] On the other hand, in a case where the actual AE waveform signal and the ideal AE waveform signal are not similar (for example, a state where the waveform level of the actual AE waveform signal is below a prescribed value continues, or the waveform level of the actual AE waveform signal exceeds a prescribed upper threshold value) and the determination in step ST8 is NO, the process proceeds to step ST10 and the retry counter is incremented by 1.

[0072] In step ST11, it is determined whether the count value of the retry counter reaches a prescribed value B (for example, 2). In a case where the count value of the retry counter does not reach the prescribed value and the determination is NO, the process returns to step ST1 and the reference position determination process is performed again.

[0073] On the other hand, in a case where the count value of the retry counter reaches the prescribed value B and the determination in step ST11 is YES, the process proceeds to step ST12, the gear grinding device 10 is stopped, and an alarm is output using the alarm output section 47. That is, an alarm display on a monitor screen provided by the gear grinding device 10, a voice-based warning, or the like is performed to urge the operator to perform maintenance for properly performing the reference position determination process.

[0074] Effects of Embodiments

[0075] As explained above, in the present embodiment, even in a case where the influence of heat causes the shaft spacing of the grinding stone 20 and the dressing tool 331 to change, the position determined based on the information of the position at which the grinding stone 20 and the dressing tool 331 contact is used as the dressing reference position, and the grinding stone 20 is cut and formed with a prescribed feed amount, so the change in the shaft spacing does not have an influence, and the grinding stone 20 can be cut with the dressing tool 331 at the target feed amount. As a result, the finished diameter of the dressing stone 20 after dressing can be properly obtained, and the machining accuracy of the workpiece W by the dressing stone 20 can be maintained high. That is, even in an environment that is not a constant temperature greenhouse, the finished diameter of the dressing stone 20 after dressing can be properly obtained, and the machining accuracy of the workpiece W by the dressing stone 20 can be maintained high. In addition, the shaft spacing does not need to be measured using the contact detector or the contact sensor, so it is possible to avoid the problems (increase in cost, increase in movement restrictions of the parts of the machining device, and the like) that occur when the contact detector or the contact sensor is provided. Furthermore, the feed amount of the grinding stone 20 can be properly set, so it is possible to prevent damage to the grinding stone 20 due to excessive contact of the dressing tool 331.

[0076] In addition, in the present embodiment, in the reference position determination processing, the phases of the dressing tool 331 and the thread-like groove of the grinding stone 20 are aligned in a manner such that the dressing tool 331 engages with the thread-like groove of the grinding stone 20 at a central portion in a direction along the rotational axis of the grinding stone 20, so that the grinding stone 20 and the dressing tool 331 are brought into contact. That is, the presence or absence of contact between the grinding stone 20 and the dressing tool 331 is determined at substantially the same phase position each time. Thus, the coordinate position of the grinding stone 20 at the time of contact between the grinding stone 20 and the dressing tool 331 can be obtained with high accuracy.

[0077] - Modification 1 -

[0078] Next, Modification 1 will be described. In the foregoing embodiment, the reference position determination processing is performed at an early stage of each time the dressing is performed. The present modification performs the reference position determination processing as needed instead of the above-described manner.

[0079] Specifically, the reference position determination processing is performed on the condition that the change in the environmental temperature during the period between the previous dressing and the next dressing is equal to or greater than a prescribed value. More specifically, the change in the temperature in the room in which the gear grinding device 10 is installed, the change in the cutting oil temperature, and the like are measured in advance, and the reference position determination processing is performed on the condition that the temperature change is equal to or greater than a prescribed value.

[0080] In addition, the reference position determination processing can also be performed on the basis of an index related to the change in the environmental temperature. For example, in the case where the time during which the gear grinding device 10 is stopped is equal to or greater than a prescribed time, the reference position determination processing is performed at an early stage of each time the dressing is performed a prescribed number of times after the gear grinding device 10 is started. This takes into account the fact that, in the case where the time during which the gear grinding device 10 is stopped is equal to or greater than a prescribed time, the change in the temperature of the gear grinding device 10 is likely to increase after the gear grinding device 10 is started, and the change in the axial distance between the grinding stone 20 and the dressing tool 331 is likely to increase. Furthermore, the index related to the change in the environmental temperature can also be the time of day. For example, the rate of increase in the air temperature per unit time in the morning is greater than at noon, and the rate of decrease in the air temperature per unit time in the evening is greater than at noon, so the reference position determination processing is performed only during this time period.

[0081] - Modification 2 -

[0082] Next, Modification 2 will be described. In the foregoing embodiment, when the actual AE waveform signal and the ideal AE waveform signal are not similar, the reference position determination processing is implemented again until the count value of the retry counter reaches a prescribed value B. The present application is not limited to this, and the gear grinding device 10 can be stopped immediately (without implementing the reference position determination processing again) and an alarm can be output using the alarm output portion 47 when the actual AE waveform signal and the ideal AE waveform signal are not similar. Figure 9is a flowchart showing the sequence of the dressing processing in this case. In this flowchart, the same step numbers are attached to the same steps as in the flowchart of the above-described embodiment of the reference position determination processing. Figure 8 Figure 9 As shown in the flowchart of the reference position determination processing, when the actual AE waveform signal and the ideal AE waveform signal are not similar and the determination in step ST8 is NO, the processing proceeds to step ST12, the gear grinding device 10 is stopped, and an alarm is output using the alarm output section 47. That is, an alarm display on a monitor screen provided in the gear grinding device 10, a voice-based warning, or the like is performed to urge the operator to perform maintenance for properly performing the reference position determination processing.

[0083] - Modification 3 -

[0084] Next, Modification 3 will be described. In the above-described embodiment, when the deviation of the coordinate position of the grinding stone 20 at the contact time point (the contact time point of the grinding stone 20 and the dressing tool 331) determined by the contact determination section 42 (this time contact coordinate position) from the dressing reference position used in the last dressing (last dressing reference position) is equal to or more than a prescribed threshold value A (for example, 5 μm), the this time contact coordinate position is determined as the next dressing reference position. That is, the update of the dressing reference position is performed, and the dressing is started. This modification is substituted for this, even if the deviation of the this time contact coordinate position from the last dressing reference position is equal to or more than the prescribed threshold value A, in the case where the deviation is extremely large, it is possible that some kind of trouble (trouble of the AE sensor 210 causes false monitoring, trouble of the operation sequence, or the like) occurs, and thus the stop of the gear grinding device 10, the output of the alarm are performed. In this modification, the determination of whether the dressing is properly performed is not performed using the determination of whether the actual AE waveform signal and the ideal AE waveform signal are similar. Also, it is not limited to this, in the case where the deviation of the this time contact coordinate position from the last dressing reference position is extremely large, the stop of the gear grinding device 10 or the output of the alarm can be performed, and the determination of whether the dressing is properly performed using the determination of whether the actual AE waveform signal and the ideal AE waveform signal are similar can be performed at the time of performing the dressing.

[0085] Figure 10 is a block diagram showing the control system in this modification. In this Figure 10 , the same reference numerals are attached to the same functional sections as in the block diagram of the above-described embodiment of the Figure 5 . As this Figure 10 ​As shown, in the control system of this modified example, the contact determination unit 42, as a function of the contact determination unit, detects that the grinding stone 20 is in contact with the dressing tool 331 based on the AE waveform signal output from the AE sensor 210. If the deviation between the previous dressing reference position and the current contact coordinate position exceeds a predetermined threshold (e.g., 100 μm), an alarm message is output to the alarm output unit 47. Furthermore, the alarm output unit 47, upon receiving this alarm message, outputs an alarm as in the above embodiment, and performs alarm display on the monitor screen of the gear grinding apparatus 10, voice-based warnings, etc.

[0086] Figure 11 This is a flowchart illustrating the sequence of trimming processes in this modified example. In this flowchart, the process is compared to that in the above-described embodiment. Figure 8 The same steps in the flowchart are labeled with the same step number. For example... Figure 11 As shown, if the result is YES in step ST5, proceed to step ST13, compare the current contact coordinate position with the previous adjustment reference position, and determine whether these deviations are below the specified threshold C (e.g., 100 μm).

[0087] Then, if the result in step ST13 is YES, the process proceeds to step ST6, where the current contact coordinate position is determined as the reference position for the next adjustment. On the other hand, if the result in step ST13 is NO (when the deviation between the current contact coordinate position and the previous adjustment reference position is extremely large), the process proceeds to step ST12, the gear grinding device 10 is stopped, and an alarm is output through the alarm output unit 47. Afterward, the process returns to step ST1, and the reference position determination process is performed again.

[0088] In addition, if the deviation between the current contact coordinate position and the previous dressing reference position is less than the specified threshold A and is determined as NO in step ST5, and dressing begins in step ST7, or if the deviation between the current contact coordinate position and the previous dressing reference position is less than the specified threshold C and is determined as YES in step ST13, and the current contact coordinate position is determined as the next dressing reference position in step ST6, and dressing begins in step ST7, the above-mentioned step ST8 processing (the determination process of whether the actual AE waveform signal and the ideal AE waveform signal are similar) is not implemented, and dressing continues. After the dressing tool 331 performs the cutting action (the cutting action based on the specified feed rate) on the grinding stone 20 repeatedly a specified number of times, dressing ends in step ST9, and the process moves to the next grinding operation of the workpiece W.

[0089] In the above-described modification example, as in the case of the foregoing embodiment, the grinding stone 20 can be cut with the dressing tool 331 at the intended amount of feed without being affected by the change in the distance between the shafts. As a result, the finished diameter of the dressing stone 20 can be appropriately obtained, and the machining accuracy of the stone 20 to the workpiece W can be maintained high. In particular, in Modification Example 3, in the case where some kind of trouble such as non-monitoring due to trouble of the AE sensor, trouble of the operation sequence, or the like occurs, the processing action corresponding thereto can be implemented.

[0090] -Other Embodiments-

[0091] Further, the present application is not limited to the above-described embodiments and each of the above-described modification examples, but can be all modifications included in the scope of the claims and the scope equivalent thereto.

[0092] For example, in the above-described embodiments and each of the above-described modification examples, the case where the present application is applied to the gear grinding device 10 is described. The present application is not limited to this, but can be applied to various machining devices that perform dressing of a tool using a dressing tool such as a honing device or the like.

[0093] Industrial Applicability

[0094] The present application can be applied to a machining device that performs dressing of a grinding stone for gear grinding machining using a dressing tool.

Claims

1. A processing apparatus, characterized in that, The processing apparatus includes: Tools are used to process workpieces; A dressing tool that can contact and separate relative to the tool, and cuts the tool from a dressing reference position with a specified feed rate to shape the tool; The sensor, whose output level changes according to the contact between the tool and the dressing cutter; and The control unit monitors the contact between the tool and the dressing cutter based on the output of the sensor. The control unit performs the following reference position determination process: in the early stage of the dressing process, the tool and the dressing cutter are brought relatively close together, the contact between the tool and the dressing cutter is monitored based on the output of the sensor, and the dressing reference position is determined based on the information of the monitored contact position.

2. The processing apparatus according to claim 1, characterized in that, If the deviation between the adjustment reference position during the previous adjustment and the contact position obtained through the current reference position determination process is less than a predetermined threshold, the control unit determines the adjustment reference position during the previous adjustment as the adjustment reference position for the next adjustment. On the other hand, if the deviation between the adjustment reference position during the previous adjustment and the contact position obtained through the current reference position determination process is above a predetermined threshold, the control unit will determine the contact position obtained through the reference position determination process as the adjustment reference position for the next adjustment.

3. The processing apparatus according to claim 1 or 2, characterized in that, The dressing is performed each time the tool has processed the workpiece a predetermined number of times. Whenever the aforementioned adjustment is performed, the control unit performs the reference position determination process in its early stage.

4. The processing apparatus according to claim 1 or 2, characterized in that, The dressing is performed each time the tool has processed the workpiece a predetermined number of times. The control unit switches between implementing and not implementing the reference position determination process based on the change in ambient temperature or an index related to the change in ambient temperature during the period between the previous adjustment and the next adjustment.

5. The processing apparatus according to claim 1 or 2, characterized in that, The processing apparatus includes a storage unit that stores the output information of the sensor during the dressing process, assuming that the tool is being shaped with a predetermined feed rate. The output information of the sensor acquired during the adjustment is compared with the stored output information of the sensor. If the deviation between these output information is greater than a specified amount, an anomaly handling is performed.

6. The processing apparatus according to claim 5, characterized in that, The abnormal situation is handled as follows: the adjustment is stopped and the reference position determination process is re-implemented.

7. The processing apparatus according to claim 5, characterized in that, The abnormal situation is handled as follows: the repair is stopped and an alarm is issued.

8. The processing apparatus according to claim 1 or 2, characterized in that, The workpiece is a gear. The tool is a grinding stone that rotates when grinding the tooth surface of the gear.

9. The processing apparatus according to claim 8, characterized in that, In the reference position determination process, information about the contact position is obtained by bringing the dressing tool into contact with the central portion along the rotation axis of the grinding stone.

10. The processing apparatus according to claim 1 or 2, characterized in that, The sensor is an AE sensor.

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